AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 321 PM MDT THU JUN 26 2008 .SHORT TERM... (TONIGHT AND FRIDAY) ...MAIN CONCERN IS "DRY" THUNDERSTORMS I-25 CORRIDOR/MOUNTAINS/HIGH VALLEYS AND "WET" STRONG/SEVERE THUNDERSTORMS SOUTHEAST CO THROUGH THIS EVENING AND AGAIN FRIDAY AFTERNOON... CURRENTLY...WATER VAPOR IMAGERY AND RUC MODEL UPPER AIR ANALYSES DID SHOW A FRAGMENTED 500-300MB SHORTWAVE TROUGH MOVING NORTHEASTWARD OUT OF THE DESERT SOUTHWEST AND FOUR CORNERS AREA THIS MORNING AND EARLY AFTERNOON. I WAS THINKING...AND STILL...THIS MIGHT BE THE TRIGGER FOR AT LEAST ISOLATED SHOWERS/THUNDERSTORMS TO DEVELOP. REGIONAL RADAR DID SHOW THE FIRST SHOWERS/THUNDERSTORMS DEVELOPING ALONG THE PALMER DIVIDE AND NORTH CENTRAL CO MOUNTAINS EARLY THIS AFTERNOON. THE LOW LEVEL FUEL HAS BEEN "MIXING OUT" WITH SURFACE DEW POINTS DROPPING INTO THE 20S AND TEEN ALONG I-25 CORRIDOR PUEBLO TO RATON MESA AND ACROSS THE MOUNTAINS/HIGH VALLEYS. DEW POINTS IN THE 40S TO LOWER 50S WERE HANGING ON ACROSS THE PALMER DIVIDE INTO THE FAR SOUTHEASTERN CO PLAINS...BUT WITH RELATIVELY DRIER AIR ALOFT...THESE DEW POINTS MAY TANK...TOO. SURFACE TEMPERATURES PRETTY WARM...WELL IN THE 90S...APPROACHING 100F...BELOW 6K FT MSL. REST OF THIS AFTERNOON AND TONIGHT...I HAVE DEFINITELY TRIMMED BACK POPS/WX ALONG THE I-25 CORRIDOR AND ACROSS THE MOUNTAINS/HIGH VALLEYS. GIVEN THE POTENTIAL TRIGGER SHORTWAVE MOVING THROUGH THE CENTRAL ROCKIES ALONG WITH ENOUGH HEATING AND INSTABILITY...THERE IS STILL A CHANCE FOR ISOLATED THUNDERSTORMS TO DEVELOP ACROSS MUCH OF THE COUNTY WARNING AREA THROUGH THIS EVENING. PRIMARY STORM TYPE SHOULD BE PULSE DOWNBURST WINDS ALONG I-25 CORRIDOR PUB-RATON MESA AND ACROSS THE MOUNTAINS/HIGH VALLEYS. A FEW STRONG TO MAYBE MARGINAL SEVERE MIGHT BE POSSIBLE FROM THE PALMER DIVIDE TO THE FAR SOUTHEASTERN CO PLAINS GIVEN A LITTLE MORE CONVECTIVE AVAILABLE ENERGY IN THESE AREAS THIS EVENING. GENERALLY ALONG THE I-25 CORRIDOR AND MOUNTAINS/HIGH VALLEYS...ISOLATED "DRY" THUNDERSTORMS WILL BE THE RULE GIVEN VERY LOW HUMIDITY VALUES IN THE SUB-CLOUD LAYER PER THE CLASSIC INVERTED-V SOUNDING DATA...ESPECIALLY WITH LCL HEIGHTS ABOUT 2K-4K FT HIGHER THAN THE FREEZING LEVEL AND A VERY UNSTABLE AND "DRY" SUB-CLOUD LAYER. PRIMARILY LOOKING AT CLOUD TO GROUND LIGHTNING STRIKES...WIND GUSTS UP TO 55 MPH...AND VERY LITTLE OR NO RAINFALL. COVERAGE SHOULD BE RATHER LOW...SO NO RED FLAG WILL BE ISSUED FOR DRY LIGHTNING...BUT "DRY THUNDERSTORMS" WILL BE MENTIONED IN THE FWF TEXT PRODUCT. FRIDAY...A CHALLENGING DAY. MODELS STILL SUGGEST A COLD FRONT TO MOVE THROUGH EAST CENTRAL AND SOUTHEAST CO PRIMARILY DURING THE AFTERNOON. TRYING TO TIME THESE BOUNDARIES ARE QUITE THE CHALLENGE...AS SOMETIMES THEY ARE FASTER. I REALLY DON`T SEE ANY SIGNALS OF A FASTER FRONTAL PUSH OVERNIGHT AND FRIDAY MORNING. SO WILL PLAN ON THE FRONT "OOZING" INTO EAST CENTRAL AND SOUTHEAST CO DURING THE AFTERNOON. THE AIR MASS AHEAD AND BEHIND THIS BOUNDARY WILL BE DRASTICALLY DIFFERENT. SOUTH AND WEST OF THE BOUNDARY...VERY LOW DEW POINTS WILL CONTINUE...WHILE SURFACE DEW POINTS IN THE 40S/50S WILL BE COMMON BEHIND THE FRONT. GENERALLY...ALONG THE FRONTAL BOUNDARY AND SOUTH AND WESTWARD...THERE IS VERY LITTLE CHANCE FOR PRECIPITATION AND MAINLY A "DRY" THUNDERSTORM OR "VIRGA SHOWER BOMBS" THREAT...ESPECIALLY OVER THE MOUNTAINS/HIGH VALLEYS AGAIN. AGAIN...THINK THE POTENTIAL COVERAGE IS LOW ISOLATED AT BEST...SO NO FIRE WEATHER WATCH FOR DRY LIGHTNING...BUT WILL MENTION "DRY" THUNDERSTORMS IN THE FWF AND DISCUSSION FOR THESE AREAS. AHEAD OF THE FRONTAL BOUNDARY...TEMPERATURES WILL BE VERY WARM/HOT...PROBABLY 90S TO AROUND 100F AGAIN. ALONG AND BEHIND THE FRONT WILL BE MORE OF A "WET" THUNDERSTORM POTENTIAL WITH SOME STORMS POSSIBLY STRONG-SEVERE. SURFACE-BASED CAPES WILL BE 1K-2.5K J/KG WITH SURFACE-BASED LIFTED INDICES OF -4C TO -6C...WHICH CONVECTIVE ARE VERY RESPECTABLE IN TERMS OF INSTABILITY AND AVAILABLE ENERGY. ASSUMING THE NAM-WRF IS CORRECT WITH ITS SURFACE DEW POINT FORECAST OF 50S DEW POINTS BEING SHOVED UP AGAINST THE EASTERN MOUNTAINS. THERE WILL BE WEAK CONVECTIVE INHIBITION ALONG AND BEHIND THE FRONT...BUT THERE MIGHT BE ENOUGH LOW LEVEL CONVERGENCE TO FORCE A BREAK-THROUGH TO FREE CONVECTION. 0-6KM BULK SHEAR VALUES WILL BE 30-50KTS...WHICH COULD SUPPORT SUPERCELLS. IT MAY BE A MIX OF ORDINARY...MULTICELLULAR...AND SUPERCELLS ALONG AND JUST BEHIND THE FRONTAL BOUNDARY. IF THE LOW LEVEL BOUNDARY IS SLOW OR STATIONARY...THEN A BRIEF TORNADO COULD NOT BE RULED OUT...BUT THE PROBABILITY IS PRETTY LOW. METZE .LONG TERM... FRIDAY NIGHT THROUGH THURSDAY) ...MAIN CHALLENGE IS STRENGTH AND AMOUNT OF CONVECTION SATURDAY... .FRIDAY NIGHT AND SATURDAY...SURFACE COLD FRONT SHOULD PASS THROUGH THE REGION BY MID EVENING FRIDAY WITH UPSLOPE FLOW CONTINUING ON THE PLAINS AND EASTERN MOUNTAINS INTO SATURDAY. NAM AND GFS HAS DEWPOINTS IN THE LOWER 50S ON THE PLAINS SATURDAY. WITH MODEST NORTHWEST FLOW ALOFT...BULK SHEARS ARE FORECAST TO BE AROUND 30 KNOTS WHICH IS IN THE LOWER END OF THE RANGE FOR SEVERE CONVECTION. HAVE SOME CONCERNS FOR THE AMOUNT OF CONVECTION ON SATURDAY. MODEL SOUNDINGS SHOW A CAP AROUND 650 MB THOUGH THE MORNING. IN THE AFTERNOON THE CAP WEAKENS IN THE MODELS...BUT THIS MAY BE THE RESULT OF THE CONVECTIVE SCHEMES GETTING INITIATED. GFS AND NAM HAVE A SHORTWAVE PASSING TO THE NORTHEAST DURING THE MORNING...AND THE SUBSIDENCE BEHIND THIS SHORTWAVE MAY BE STRENGTHENING THE INVERSION. DECIDED NOT TO MAKE MAJOR CHANGES TO THE POP GRIDS AT THIS TIME...WITH THE BEST CHANCES FOR CONVECTION OVER THE EASTERN MOUNTAINS AND INTERSTATE 25 CORRIDOR. CAP WOULD BE WEAKER IN THESE LOCATIONS...AND POOLING OF MOISTURE ALONG THE MOUNTAINS WILL TEND TO INCREASE INSTABILITY. MODEL CAPE FIELDS SUGGEST A SIMILAR PATTERN FOR CONVECTION. OVER THE REMAINDER OF THE AREA...NORTHWEST FLOW AND SUBSIDENCE BEHIND THE TROUGH WILL TEND TO DRY OUT THE ATMOSPHERE. KEPT 10 POPS FOR THE AFTERNOON WITH THE POTENTIAL FOR A FEW MOSTLY DRY THUNDERSTORMS. .SUNDAY AND MONDAY...AS RIDGE TO THE WEST STRENGTHENS...FLOW ALOFT WILL BECOME NORTH NORTHERLY. LOWER LEVELS WILL GRADUALLY DRY WITH DECREASED CHANCES FOR THUNDERSTORMS ON THE PLAINS. WITH WEAK HIGH PRESSURE STAYING TO THE EAST...DID NOT WANT TO REMOVE POPS ENTIRELY. SUSPECT THERE WILL BE ENOUGH LOW LEVEL MOISTURE IN WEAK UPSLOPE FLOW TO GENERATE SOME THUNDERSTORMS...WITH THE GREATEST CHANCES FOR CONVECTION OVER THE EASTERN MOUNTAINS. IN THE REMAINING AREAS...GFS AND EC CONTINUES TO HAVE A WEAK MONSOON LIKE PLUME OF MID LEVEL MOISTURE INTO WESTERN COLORADO. WILL KEEP SOME ISOLATED POPS FOR AFTERNOON AND EVENING CONVECTION. .TUESDAY THROUGH THURSDAY...RIDGE BUILDS OVER THE REGION...WITH ENSEMBLE MEANS FOR GFS SUGGESTING WEAK LEE TROUGH NEAR THE KANSAS BORDER. EC AND GFS HAVE A RIBBON OF MID LEVEL MOISTURE MOVING NORTH FROM MEXICO. IT LOOKS LIKE SUMMER...AND HAVE A BROAD BRUSH SUMMER FORECAST OF AFTERNOON AND EVENING THUNDERSTORMS WITH BEST CHANCES OVER THE MOUNTAINS. MOISTURE IN MONSOON PLUMES TYPICALLY ARE MODEST THIS TIME OF YEAR AND DO NOT ANTICIPATE SIGNIFICANT PRECIPITATION FROM CONVECTION. --PGW-- && .AVIATION... PER SHORT TERM DISCUSSION...FOR ALL FORECAST TAF...ISOLATED SHOWERS AND THUNDERSTORMS THROUGH THIS EVENING AND FRIDAY AFTERNOON WILL LEAD TO VARIABLE WIND DIRECTION AND SPEEDS OF 20-30KTS WITH GUSTS UP TO 45KTS AT TIMES. METZE && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 17/06 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 941 AM MDT THU JUN 26 2008 .UPDATE... SATELLITE IMAGERY AND MORNING SOUNDING DATA INDICATE MID LEVEL MOISTURE CREEPING TOWARD THE AREA FROM THE SOUTH. RUC ANALYSIS ALSO DEPICTS A WEAK SHORTWAVE TROUGH OVER THE FOUR CORNERS AREA AND CENTRAL UTAH THIS MORNING WHICH LOOKS REASONABLE GIVEN THAT THUNDERSTORMS HAVE ALREADY FORMED OVER THE MOUNTAINS OF SOUTHEAST UTAH. THIS WAVE SHOULD MIX OUT THE WEAK SUBSIDENCE INVERSION NEAR 500MB ON THE GJT SOUNDING AND WITH DAYTIME HEATING EXPECT ISOLATED THUNDERSTORMS TO DEVELOP ACROSS THE NORTHERN HIGH TERRAIN AS WELL AS THE SOUTH. WILL MAKE ADJUSTMENTS TO POP AND SKY GRIDS IN MORNING UPDATE...OTHERWISE THE GOING FORECAST LOOKS FINE. && .PREVIOUS DISCUSSION...SHORT TERM...TODAY THROUGH FRIDAY NIGHT... TWO MINOR FEATURES TO WATCH TODAY...ONE FROM THE GREAT BASIN AND THE OTHER OVER ARIZONA. SHORT WAVE MOVING ACROSS THE NRN INTERMOUNTAIN REGION DRAGS A WEAK COOL FRONT ACROSS THE NRN GREAT BASIN. THIS IS THE TIME OF YEAR COOL FRONTS STRUGGLE TO PENETRATE INTO OUR FORECAST AREA. THIS IS NO EXCEPTION AS THE SHORT WAVE DOES NOT HAVE A DIGGING JET ON THE BACK SIDE UNTIL IT REACHES THE NRN PLAINS. HOWEVER...THE MODELS DO INDICATE THAT THE SHALLOW COOL FRONT DOES MOVE SOUTH OF THE COLORADO AND WYOMING BORDER THIS EVENING. THIS MAY NOT HAVE MUCH OF AN IMPACT ON SENSIBLE WEATHER EXCEPT TO ENHANCE AFTERNOON BREEZES AROUND 15 TO 20 MPH OVER THE NRN VALLEYS. WEAK CLOSED LOW CIRCULATION OFF THE SRN CALIFORNIA COAST IS SENDING A STREAM OF MOISTURE NORTHWARD OVER SRN AND ERN ARIZONA. LOW LEVELS REMAIN DRY BUT SUFFICIENT MID TO HIGH LEVEL MOISTURE FOR ISOLATED THUNDERSTORMS OVER THE SAN JUAN AND WEST ELK MOUNTAINS. THE GFS AND SREF MODEL SUGGEST THAT ISOLATED NOCTURNAL THUNDERSTORMS MAY OCCUR OVER SW COLORADO. THIS CANNOT BE DISCOUNTED AS ISOLATED NOCTURNAL THUNDER OVER MONTEZUMA COUNTY FROM ARIZONAS CONVECTIVE DEBRIS IS NOT UNUSUAL. ON FRIDAY...DEFORMATION AXIS WILL BE ORIENTED WEST-EAST OVER SRN UTAH AND SRN COLORADO. NORTH OF THIS AXIS...THE PACIFIC HIGH CENTERED OVER THE NRN GREAT BASIN HAS A TENDENCY TO CAP CONVECTIVE POTENTIAL. INSTABILITY LOOKS VERY MARGINAL...BUT A FEW STORMS WILL STILL OCCUR OVER THE HIGH MOUNTAINS OF THE WEST SLOPE. .LONG TERM...SATURDAY THROUGH THURSDAY... HOT AND MOSTLY DRY CONDITIONS CONTINUE FOR THESE PERIODS WITH SOME UNCERTAIN PROMISE OF INCREASED MOISTURE BY MID NEXT WEEK. SATURDAY: WITH THE RIDGE AXIS TO OUR WEST...FROM EL PASO TO THE 4- CORNERS TO BOISE...A WARM NW FLOW CONTINUES. MOISTURE VERY LIMITED FOR NO MENTION OF THUNDERSTORMS FOR NOW. SUNDAY-MONDAY: RIDGE AXIS TRANSLATES OVERHEAD AS THE WEST-COAST TROUGH GETS ACTIVE. THIS ADD A FEW DEGREES TO ALREADY HOT AFTERNOONS. A STRENGTHENED MID-LEVEL SUBSIDENCE INVERSION WILL LIMIT THUNDERSTORM ACTIVITY. WINDS ALOFT VERY LIGHT WITH SFC WINDS TERRAIN DOMINATED. TUESDAY-THURSDAY: RIDGE GETS SQUASHED JUST A BIT AS THE WEST-COAST TROUGH EJECTS ENERGY ACROSS THE GREAT BASIN. RESULTING SW FLOW PROMISES SOME SLIGHT MOISTURE INCREASE FAVORING THE SOUTHERN MOUNTAINS WITH THUNDERSTORM POTENTIAL. SLIGHTLY COOLER TEMPERATURES POSSIBLE WITH THIS MOISTURE BUT DID NOT FULLY FOLLOW MEX TREND TOWARDS CLIMATOLOGY. && .AVIATION... VFR PREVAILS WITH ISOLATED THUNDERSTORMS FORMING OVER THE HIGH TERRAIN. MOST STORMS WILL DISSIPATE WITH SUNSET...BUT A FEW STORMS WILL BE POSSIBLE THROUGH THE NIGHT OVER EXTREME SOUTHWEST COLORADO. GUSTY ERRATIC WINDS WILL BE POSSIBLE WITH THE STORMS. && .HYDROLOGY... THE VERY WARM TEMPERATURES ACROSS THE AREA FOR THE NEXT SEVERAL DAYS WILL CONTINUE TO EAT AWAY AT THE HIGH MOUNTAINS SNOWPACK WITH RUNOFF AND RIVER AND STREAM FLOWS EXPECTED TO REMAIN ON A GRADUAL DOWNWARD TREND. AFTER COORDINATION WITH THE EMERGENCY MANAGER WENT AHEAD AND CANCELLED THE REMAINING FLOOD ADVISORY FOR THE EAGLE RIVER BELOW GYPSUM. ALTHOUGH WATER LEVELS ARE DECREASING FLOWS REMAIN COLD... SWIFT...AND TURBULENT AND CAUTION IS URGED WHEN AROUND RIVERS AND STREAMS. STAY TUNED TO THE LATEST FORECASTS AND FLOOD INFORMATION AT WEATHER.GOV/GJT && .GJT WATCHES/WARNINGS/ADVISORIES... .CO...NONE. .UT...NONE. $$ UPDATE.........TAL SHORT TERM.....PF LONG TERM......JOE AVIATION.......PF HYDROLOGY......TAL co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 156 AM EDT THU JUN 26 2008 .SYNOPSIS... HIGH PRESSURE WILL MOVE EAST OF THE REGION TONIGHT AS A WARM FRONT AND UPPER LEVEL DISTURBANCE APPROACH FROM THE OHIO VALLEY. THESE FEATURES WILL BRING SHOWERS AND THUNDERSTORMS THURSDAY MORNING. A TROUGH OF LOW PRESSURE MAY TRIGGER ADDITIONAL THUNDERSTORMS DURING THE AFTERNOON AND EARLY EVENING...SOME OF WHICH MAY BE SEVERE. HIGH PRESSURE WILL BRIEFLY BUILD BACK IN FOR FRIDAY...HOWEVER MORE INCLEMENT WEATHER IS IN STORE FOR THE WEEKEND. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... QUICK UPDATE TO ACCOUNT FOR CURRENT TRENDS IN TEMPS AND DEWPOINTS...WHICH HAVE BEEN FOLLOWING METMOS VALUES QUITE NICELY THUS FAR THIS EVENING. HIGH LEVEL CLOUDS WILL CONTINUE TO INCREASE AHEAD OF DEVELOPING MCS ACROSS OHIO...WHICH HAS CLOUD TOPS COOL CLOSE TO -70 C OVER THE PAST FEW HOURS OVER WESTERN OHIO. MUCH OF THIS ACTIVITY SHOULD CURVE WELL SOUTH OF THE AREA...AS THE ACTIVITY WILL LIKELY FOLLOW THE THICKNESS PATTERN. HOWEVER...BOTH THE LATEST NAM12 AND RUC13 DATA SHOW ADDITIONAL SHOWERS/ELEVATED T-STORM ACTIVITY TO DEVELOP TO NORTH OF THIS MCS ACROSS SOUTHERN ONTARIO...AND THIS IDEA IS SUPPORTED BY THE INCREASING LOW LEVEL JET EVIDENT ON THE KDTX AND KBUF 00Z SOUNDINGS. THIS LOOSELY ORGANIZED ACTIVITY WILL EVENTUALLY TRAVERSE NEW YORK STATE FOR THE SECOND HALF OF THE OVERNIGHT AND COULD BEGIN IMPACTING THE WESTERN ZONES PRIOR TO SUNRISE...SO HAVE INCLUDED CHC POPS IN THESE AREAS TO ACCOUNT FOR THIS. HAVE KEPT MINS ALONE...AS OUR CURRENT FORECAST LOWS SEEM TO BE IN LINE WITH LATEST STATISTICAL PROG NUMBERS. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/... SEVERAL UNCERTAINTIES EXIST REGARDING THE FORECAST FOR THUR. THE MAIN QUESTION FOR THE MORNING HOURS WILL INEVITABLY BE HOW THE MCV EVOLVES. IF A WIDESPREAD RAIN SHIELD FORMS...THIS COULD STABILIZE THE ENVIRONMENT FOR MUCH OF THE REST OF THE DAY. FOR NOW WILL MENTION LIKELY POPS SOUTH OF ALBANY...WITH HIGH CHANCE NORTHWARD. BOTH NAM/GFS SUGGESTING THE HIGHEST PROBABILITY FOR A CONVECTIVE COMPLEX ASSOC WITH THE MCV TO MOVE THROUGH WILL BE ACROSS SOUTHERN AREAS. THERE IS A POTENTIAL FOR SEVERE THUNDERSTORMS THUR AFTERNOON INTO THE EARLY EVENING...HOWEVER THIS THREAT IS CONDITIONAL. DEVELOPMENT WILL BE HIGHLY DEPENDENT ON HOW MUCH DE-STABILIZATION CAN OCCUR AFTER THE INITIAL MCV OR WHATEVER IS LEFT OF THIS FEATURE MOVES THROUGH. THERE MAY BE JUST ENOUGH SUBSIDENCE IN ITS WAKE TO ALLOW FOR SOME BREAKS OF SUNSHINE LATE MORNING/EARLY AFTERNOON TIME FRAME TO ALLOW FOR SBCAPE VALUES TO EXCEED 1000 J/KG. SHOULD THIS OCCUR...OTHER PARAMETERS WILL BE IN PLACE FOR STORMS TO BECOME SEVERE. LOW LEVEL MOISTURE WILL BE INCREASING THROUGH THE DAY...AND 0-6 KM BULK SHEAR WILL BE IN THE 30-40 KT RANGE WHICH WOULD SUPPORT BOWING SEGMENTS AND ORGANIZED MULTICELL CLUSTERS. ALSO...THE SHORT WAVE CURRENTLY OVER ILLINOIS EVEN IN A WEAKENED STATE MAY BE A FACTOR AND PROMOTE FORCING...AS WELL AS A HINT OF A SURFACE TROF MOVING THROUGH. THIS IS HIGHLY DEPENDENT ON HOW MUCH INSTABILITY CAN BUILD THOUGH. SPC HAS AREA IN SLIGHT RISK...AND WILL MENTION THREAT IN HWO. CONVECTIVE ACTIVITY SHOULD DIMINISH AFTER SUNSET...DUE TO LOSS OF DAYTIME HEATING AND WEAK HIGH PRESSURE BUILDING IN. WILL KEEP FORECAST DRY OVERNIGHT THUR THROUGH FRI FOR MUCH OF THE AREA. NAM HINTING AT A WEAK BOUNDARY POSSIBLE GENERATING ENOUGH LOW LEVEL CONVERGENCE FOR ISOLD STORMS ACROSS SOUTHERN AREAS. OTHERWISE IT WILL BE A WARM DAY WITH AIR MASS IN WAKE OF THURSDAY/S SYSTEM EVEN WARMER...AND WITH WESTERLY FLOW ENHANCING DOWNSLOPE POTENTIAL IN NORTH-SOUTH ORIENTED VALLEYS. YET MORE UNSETTLED WEATHER IN STORE FOR LATE FRI NIGHT INTO SAT...AS A MORE SIGNIFICANT AND SLOWER MOVING WARM FRONT APPROACHES FROM THE GREAT LAKES/OHIO VALLEY. WILL MENTION HIGH CHANCE POPS STARTING EARLY SAT MORNING...LASTING THROUGH THE DAY. UNCERTAINTY EXISTS AS TO HOW FAR NORTH THE FRONT WILL PROGRESS DURING THE AFTERNOON...WITH THE POTENTIAL FOR ROBUST CONVECTION IN THE WARM SECTOR...MAINLY FROM ALBANY SOUTHWARD AS IT SEEMS NOW. TEMPS WILL BE AFFECTED AS WELL...WITH READINGS POSSIBLY ENDING UP EITHER COOLER OR WARMER THAN FORECAST. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... QUITE AN UNSETTLED EXTENDED PERIOD LOOKS TO BE SHAPING UP FOR EASTERN NEW YORK AND WESTERN NEW ENGLAND. THE PERIOD BEGINS WITH AN OCCLUDED FRONTAL BOUNDARY ATTEMPTING TO MAKE A RUN AT THE REGION WHILE A DEEP CUTOFF LOW SLOWLY PUSHES EASTWARD ACROSS THE GREAT LAKES. HAVE KEPT POPS AT LIKELY FOR SAT NIGHT INTO SUNDAY FOR EXPECTED SHOWERS AND THUNDERSTORMS. ALTHOUGH THERE IS A DECENT AMOUNT OF UNI-DIRECTIONAL DEEP LAYER SHEAR /AROUND 30 KTS/...BIGGEST THREAT WITH CONVECTION WILL PROBABLY BE HEAVY RAINFALL. GEFS PWATS LOOKS TO BE 1-2 STDS ABOVE NORMAL...AND ALONG WITH A DEEP WARM LAYER (FRZ LEVEL AROUND 14000 FT)...COULD EXPECT SOME VERY HEAVY RAINFALL RATES. OCCLUDED FRONT SHOULD PASS THROUGH THE REGION ON SUNDAY NIGHT...SO HAVE TAPERED POPS DOWN FROM LIKELY DOWN TO CHC AFTER 00Z MONDAY. SOME DIFFERENCES BETWEEN THE 12Z ECMWF AND 12Z GFS REGARDING THE PATTERN FOR MONDAY THROUGH WEDNESDAY. THE ECMWF IS MUCH FASTER WITH LIFTING OUT AND WEAKENING THE UPPER LOW OVER THE GREAT LAKES AREA...WHILE THE GFS KEEPS THE UPPER LOW OVER THE EASTERN LAKES RIGHT INTO EARLY NEXT WEEK. EVEN WHILE THE ECMWF WEAKENS THE CUTOFF...IT STILL KEEP A RATHER LARGE TROUGH SITTING OVER THE EASTERN SEABOARD THROUGH THE FIRST COUPLE DAYS OF NEXT WEEK. HAVE GENERALLY GONE WITH HPC GUIDANCE WHICH FAVORS THE ECMWF IDEA. CAN EXPECT SCT DIURNAL CONVECTION DUE TO THE COLD POOL ALOFT AND DAYTIME HEATING THROUGH AT LEAST MONDAY AND TUESDAY. 850 TEMPS WILL BOTTOM OUT TO AROUND 10 DEGREES C ON MONDAY...AND SLOWLY IMPROVE THROUGHOUT THE WEEK. THIS WILL KEEP HIGHS RATHER COOL ON MONDAY WITH UPPER 60S IN THE HIGHER TERRAIN AND LOWER 70S IN THE VALLEYS...ALTHOUGH MAX TEMPS SHOULD IMPROVE SEVERAL DEGREES EACH DAY DURING THE WEEK AS HEIGHTS SLOWLY IMPROVE. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... ID AND HIGH CLOUDS CONTINUE TO INCREASE AHEAD OF A THERMAL TROUGH AND A MESOSCALE CONVECTIVE SYSTEM OVER ERN OH AND WRN PA EARLY THIS MORNING. OTHER SHOWERS EAST OF A WARM FRONT OVER ERN MI CONTINUE TO DEVELOP OVER WRN-CNTRL NY. SOME PATCHY MVFR/IFR RADIATIONAL MIST IS LIKELY AT KGFL DUE TO RADIATIONAL COOLING THIS MORNING. WE INCLUDED A BRIEF PERIOD OF IFR MIST THERE. ELSEWHERE...VFR CONDITIONS SHOULD PREVAIL UNTIL 1400-1600 UTC...WHEN THE SHOWERS ARRIVE DUE TO THE WARM AIR ADVECTION. WE INCLUDED GENERALLY MVFR CONDITIONS WITH PERHAPS SOME ISOLD-SCT IFR CIGS/VSBYS. FOR NOW...WE KEPT IT MVFR WITH CB/S WITH ANY ELEVATED CONVECTION. SOME SCT CONVECTION MAY FIRE IN THE AFTERNOON...AND WE INCLUDED VCSH/S AND CBS FOR NOW. A MIXTURE OF VFR/MVFR CONDITIONS ARE LIKELY AFTER 0000 UTC FRI...WHEN THE ERN NY TERMINALS GET INTO A WARM SECTOR. THE WINDS WILL BE SOUTHERLY IN THE LATE MORNING THROUGH THE AFTERNOON AT 5-10 KTS...WITH SOME GUSTS AT KALB POSSIBLY CLOSE TO 20 KTS. THE WINDS WILL BECOME VRB AT 4-7 KTS AFTER 0000 UTC. OUTLOOK... FRI...VFR...ISOLD PM -SHRA/TSRA KALB SOUTH. SAT...VFR/MVFR...CHC PM SHRA/TSRA. SUN-MON...MVFR/IFR...CHC SHRAS/TSRAS. && .HYDROLOGY... A WARM FRONT AND PREFRONTAL TROUGH WILL BRING SOME SHOWERS AND THUNDERSTORMS ON THURSDAY. SOME OF THE THUNDERSTORMS MAY PRODUCE SOME BRIEF DOWNPOURS IMPACTING POORLY DRAINED AREAS...AND SMALL STREAMS. LOCALIZED RAINFALL WILL RANGE FROM A TENTH TO A HALF INCH. A VERY UNSETTLED PATTERN THIS UPCOMING WEEKEND INTO EARLY NEXT WEEK AS A SLOW MOVING COLD FRONT DRIFTS THROUGH THE REGION...PROVIDING A CONSTANT FOCUS FOR SHOWERS AND THUNDERSTORMS. THE FRONT WILL EXIT OFFSHORE NEW ENGLAND THE BEGINNING OF NEXT WEEK. MAIN STEM RIVERS SHOULD BE FINE...BUT ANY SHOWERS OR THUNDERSTORMS SATURDAY THROUGH TUESDAY COULD PRODUCE A QUICK COUPLE INCHES OF RAINFALL...WITH SOME LOCALIZED AMOUNTS POTENTIALLY OVER 2 INCHES THROUGH THE MULTI DAY EPISODE. RURAL/URBAN AND SMALL STREAM FLOODING WILL HAVE TO BE MONITORED WITH REPEATED CONVECTION IN SIMILAR AREAS. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...JPV NEAR TERM...FRUGIS SHORT TERM...JPV LONG TERM...FRUGIS AVIATION...WASULA HYDROLOGY...NAS ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIAMI FL 1116 AM EDT THU JUN 26 2008 .UPDATE... HAVE ALREADY UPDATED GRIDS TO REFLECT HIGHER POPS EXPECTED ACROSS THE NORTH-CENTRAL PORTION OF THE FORECAST AREA THIS AFTERNOON... IN THE GENERAL VICINITY OF LAKE OKEECHOBEE. THIS IS THE REGION WHERE STRONGEST LOW-LEVEL CONVERGENCE WILL LIKELY BE FOCUSED... NEAR A WEAK BOUNDARY. ALSO INCLUDED MENTION OF GUSTY WINDS/SMALL HAIL/LOCALLY HEAVY RAINFALL...BASED ON EVENTS FROM PREVIOUS DAYS. OTHERWISE...ADJUSTED WINDS UPWARD OVER THE SOUTHERN ATLANTIC WATERS...BASED ON CURRENT OBSERVATIONS...AND ADDED SCEC HEADLINE TO THESE MARINE ZONES AS WELL AS BISCAYNE BAY. ALL UPDATED PRODUCTS WILL BE ISSUED SHORTLY. 70/DD && .AVIATION DISCUSSION... /ISSUED 731 AM EDT THU JUN 26 2008/ MORNING AVIATION... THE EASTERLY WIND FLOW OF 10 TO 15 KNOTS WILL CONTINUE TODAY ACROSS SOUTH FLORIDA...EXCEPT FOR A WEST COAST SEA BREEZE THAT WILL DEVELOP EARLY THIS AFTERNOON AT AFP TAF SITE. THE EASTERLY WIND FLOW WILL ALLOW FOR ONLY SHOWERS TO AFFECT THE EAST COAST TAF SITES TODAY...AND THUNDERSTORMS AT APF TAF SITE THIS AFTERNOON. SO WILL SHOW VCSH FOR THE EAST COAST TAF SITES...AND VCTS FOR APF TAF SITE BETWEEN 18Z AND 23Z. THE SKIES AND VIS WILL REMAIN IN THE VFR CONDITIONS TODAY FOR THE EAST COAST TAF SITES AND APF TAF SITE. WILL AMEND THE APF TAF SITE AS NEEDED THIS AFTERNOON ONCE THE THUNDERSTORMS HAVE STARTED TO DEVELOP OVER THIS AREA. AVIATION...54/BNB PREV DISCUSSION... /ISSUED 455 AM EDT THU JUN 26 2008/ DISCUSSION... THE LATEST WATER VAPOR IMAGERY...RUC ANALYSIS AND THE RECENT GUIDANCE INDICATE AN UPPER LEVEL RIDGE OVER THE SOUTH FLORIDA PENINSULA. A PLUME OF UPPER LEVEL MOISTURE AND CLOUDINESS CONTINUES TO COME ACROSS THE YUCATAN PENINSULA AND ACROSS THE GULF AND OVER THE SOUTH FLORIDA PENINSULA...WITH A PERSISTENT UPPER LEVEL TROUGH WELL ESTABLISHED OVER THE WESTERN GULF. A TROPICAL WAVE SOUTH OF CUBA IS ALSO INTERACTING WITH THE SOUTHERN EXTENSION OF THE UPPER LEVEL TROUGH AND ALSO CONTRIBUTING TO CONSIDERABLE CLOUDINESS IN THE SOUTHEASTERN GULF. RECENT GUIDANCE INDICATES THAT THE MID LEVELS WILL BE DRY IN THE SHORT TERM...WITH THE AFOREMENTIONED UPPER LEVEL MOISTURE AND ASSOCIATED CIRRUS PERSISTING ACROSS THE REGION FOR AT LEAST THE NEXT SEVERAL DAYS. WITH HIGH PRESSURE DOMINATING THE SOUTH FLORIDA PENINSULA AND LACK OF DEEP LAYERED MOISTURE...ONLY EXPECTING SCATTERED SHOWERS AND THUNDERSTORMS TODAY...WITH THE EAST TO EAST SOUTHEAST LOW TO MID LEVEL WINDS FAVORING THE WESTERN INTERIOR SECTIONS AND THE NAPLES AREA THIS AFTERNOON. THIS TREND SHOULD CONTINUE THROUGH THE WEEKEND. LATEST GUIDANCE SUGGESTS THAT PWATS SHOULD BE AROUND 1.7 INCHES THROUGH THIS PERIOD...SO ISOLATED AREAS OF LOCALLY HEAVY RAINFALL ARE POSSIBLE EACH AFTERNOON THROUGH THE WEEKEND...BUT AGAIN FAVORING THE WESTERN INTERIOR AND MAINLY DURING THE AFTERNOON. MARINE... LATEST GUIDANCE INDICATES THAT EAST TO EAST SOUTHEAST FLOW WILL PERSIST OVER THE LOCAL WATERS THROUGH THE WEEKEND. IN GENERAL THE WINDS OVER THE LOCAL ATLANTIC WATERS EAST OF PALM BEACH COUNTY ARE EXPECTED TO BE IN THE 5 TO 10 KNOT RANGE...WITH 10 TO 15 KNOTS ELSEWHERE OVER THE ATLANTIC WATERS. THE OFF SHORE GULF WATERS WILL BE NEAR 10 KNOTS WITH PERIODS OF 10 TO 15 KNOTS POSSIBLE. FIRE WEATHER... NO FIRE WEATHER CONCERNS. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 91 77 90 77 / 50 30 20 10 FORT LAUDERDALE 90 79 90 80 / 40 20 20 10 MIAMI 91 79 91 78 / 40 20 20 10 NAPLES 91 74 93 75 / 50 20 30 10 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ LONG TERM...70/DD SHORT TERM/AVIATION...54/BNB fl AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MIAMI FL 731 AM EDT THU JUN 26 2008 .MORNING AVIATION... THE EASTERLY WIND FLOW OF 10 TO 15 KNOTS WILL CONTINUE TODAY ACROSS SOUTH FLORIDA...EXCEPT FOR A WEST COAST SEA BREEZE THAT WILL DEVELOP EARLY THIS AFTERNOON AT AFP TAF SITE. THE EASTERLY WIND FLOW WILL ALLOW FOR ONLY SHOWERS TO AFFECT THE EAST COAST TAF SITES TODAY...AND THUNDERSTORMS AT APF TAF SITE THIS AFTERNOON. SO WILL SHOW VCSH FOR THE EAST COAST TAF SITES...AND VCTS FOR APF TAF SITE BETWEEN 18Z AND 23Z. THE SKIES AND VIS WILL REMAIN IN THE VFR CONDITIONS TODAY FOR THE EAST COAST TAF SITES AND APF TAF SITE. WILL ADMEND THE APF TAF SITE AS NEEDED THIS AFTERNOON ONCE THE THUNDESTORMS HAVE STARTED TO DEVELOP OVER THIS AREA. && .AVIATION...54/BNB .PREV DISCUSSION... /ISSUED 455 AM EDT THU JUN 26 2008/ DISCUSSION... THE LATEST WATER VAPOR IMAGERY...RUC ANALYSIS AND THE RECENT GUIDANCE INDICATE AN UPPER LEVEL RIDGE OVER THE SOUTH FLORIDA PENINSULA. A PLUME OF UPPER LEVEL MOISTURE AND CLOUDINESS CONTINUES TO COME ACROSS THE YUCATAN PENINSULA AND ACROSS THE GULF AND OVER THE SOUTH FLORIDA PENINSULA...WITH A PERSISTENT UPPER LEVEL TROUGH WELL ESTABLISHED OVER THE WESTERN GULF. A TROPICAL WAVE SOUTH OF CUBA IS ALSO INTERACTING WITH THE SOUTHERN EXTENSION OF THE UPPER LEVEL TROUGH AND ALSO CONTRIBUTING TO CONSIDERABLE CLOUDINESS IN THE SOUTHEASTERN GULF. RECENT GUIDANCE INDICATES THAT THE MID LEVELS WILL BE DRY IN THE SHORT TERM...WITH THE AFOREMENTIONED UPPER LEVEL MOISTURE AND ASSOCIATED CIRRUS PERSISTING ACROSS THE REGION FOR AT LEAST THE NEXT SEVERAL DAYS. WITH HIGH PRESSURE DOMINATING THE SOUTH FLORIDA PENINSULA AND LACK OF DEEP LAYERED MOISTURE...ONLY EXPECTING SCATTERED SHOWERS AND THUNDERSTORMS TODAY...WITH THE EAST TO EAST SOUTHEAST LOW TO MID LEVEL WINDS FAVORING THE WESTERN INTERIOR SECTIONS AND THE NAPLES AREA THIS AFTERNOON. THIS TREND SHOULD CONTINUE THROUGH THE WEEKEND. LATEST GUIDANCE SUGGESTS THAT PWATS SHOULD BE AROUND 1.7 INCHES THROUGH THIS PERIOD...SO ISOLATED AREAS OF LOCALLY HEAVY RAINFALL ARE POSSIBLE EACH AFTERNOON THROUGH THE WEEKEND...BUT AGAIN FAVORING THE WESTERN INTERIOR AND MAINLY DURING THE AFTERNOON. MARINE... LATEST GUIDANCE INDICATES THAT EAST TO EAST SOUTHEAST FLOW WILL PERSIST OVER THE LOCAL WATERS THROUGH THE WEEKEND. IN GENERAL THE WINDS OVER THE LOCAL ATLANTIC WATERS EAST OF PALM BEACH COUNTY ARE EXPECTED TO BE IN THE 5 TO 10 KNOT RANGE...WITH 10 TO 15 KNOTS ELSEWHERE OVER THE ATLANTIC WATERS. THE OFF SHORE GULF WATERS WILL BE NEAR 10 KNOTS WITH PERIODS OF 10 TO 15 KNOTS POSSIBLE. FIRE WEATHER... NO FIRE WEATHER CONCERNS. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 90 77 90 77 / 30 20 20 10 FORT LAUDERDALE 89 79 90 80 / 30 20 20 10 MIAMI 90 79 91 78 / 20 20 20 10 NAPLES 91 74 93 75 / 40 20 30 10 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ LONG TERM...60/BD SHORT TERM/AVIATION...47/RHG fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIAMI FL 455 AM EDT THU JUN 26 2008 .DISCUSSION... THE LATEST WATER VAPOR IMAGERY...RUC ANALYSIS AND THE RECENT GUIDANCE INDICATE AN UPPER LEVEL RIDGE OVER THE SOUTH FLORIDA PENINSULA. A PLUME OF UPPER LEVEL MOISTURE AND CLOUDINESS CONTINUES TO COME ACROSS THE YUCATAN PENINSULA AND ACROSS THE GULF AND OVER THE SOUTH FLORIDA PENINSULA...WITH A PERSISTENT UPPER LEVEL TROUGH WELL ESTABLISHED OVER THE WESTERN GULF. A TROPICAL WAVE SOUTH OF CUBA IS ALSO INTERACTING WITH THE SOUTHERN EXTENSION OF THE UPPER LEVEL TROUGH AND ALSO CONTRIBUTING TO CONSIDERABLE CLOUDINESS IN THE SOUTHEASTERN GULF. RECENT GUIDANCE INDICATES THAT THE MID LEVELS WILL BE DRY IN THE SHORT TERM...WITH THE AFOREMENTIONED UPPER LEVEL MOISTURE AND ASSOCIATED CIRRUS PERSISTING ACROSS THE REGION FOR AT LEAST THE NEXT SEVERAL DAYS. WITH HIGH PRESSURE DOMINATING THE SOUTH FLORIDA PENINSULA AND LACK OF DEEP LAYERED MOISTURE...ONLY EXPECTING SCATTERED SHOWERS AND THUNDERSTORMS TODAY...WITH THE EAST TO EAST SOUTHEAST LOW TO MID LEVEL WINDS FAVORING THE WESTERN INTERIOR SECTIONS AND THE NAPLES AREA THIS AFTERNOON. THIS TREND SHOULD CONTINUE THROUGH THE WEEKEND. LATEST GUIDANCE SUGGESTS THAT PWATS SHOULD BE AROUND 1.7 INCHES THROUGH THIS PERIOD...SO ISOLATED AREAS OF LOCALLY HEAVY RAINFALL ARE POSSIBLE EACH AFTERNOON THROUGH THE WEEKEND...BUT AGAIN FAVORING THE WESTERN INTERIOR AND MAINLY DURING THE AFTERNOON. && .MARINE... LATEST GUIDANCE INDICATES THAT EAST TO EAST SOUTHEAST FLOW WILL PERSIST OVER THE LOCAL WATERS THROUGH THE WEEKEND. IN GENERAL THE WINDS OVER THE LOCAL ATLANTIC WATERS EAST OF PALM BEACH COUNTY ARE EXPECTED TO BE IN THE 5 TO 10 KNOT RANGE...WITH 10 TO 15 KNOTS ELSEWHERE OVER THE ATLANTIC WATERS. THE OFF SHORE GULF WATERS WILL BE NEAR 10 KNOTS WITH PERIODS OF 10 TO 15 KNOTS POSSIBLE. && .FIRE WEATHER... NO FIRE WEATHER CONCERNS. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 90 77 90 77 / 30 20 20 10 FORT LAUDERDALE 89 79 90 80 / 30 20 20 10 MIAMI 90 79 91 78 / 20 20 20 10 NAPLES 91 74 93 75 / 40 20 30 10 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ LONG TERM...60/BD SHORT TERM/AVIATION...47/RHG fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MELBOURNE FL 251 AM EDT WED JUN 25 2008 .DISCUSSION... CURRENTLY-TODAY...TROPICAL WAVE CURRENTLY ANALYZED BY TAFB VICINITY EASTERN CUBA AND SOUTHWARD WILL CONTINUE TO PUSH WESTWARD IN TRADE WIND BELT OVER THE CARIBBEAN. SUBTROPICAL RIDGE WITH AXIS JUST NORTH OF CANAVERAL WILL CONTINUE TO NUDGE NORTHWARD AS TROUGH WEAKENS OFF THE EASTERN SEABOARD. THIS WILL LEAD TO A DEVELOPING LIGHT ONSHORE GRADIENT FLOW AND KEEP THE LOW LEVELS MOIST. WATER VAPOR LOOP/RUC ANALYSIS SHOWS UPPER LEVEL TROUGH OVER THE GULF PRODUCING A MOISTURE PLUME FROM THE YUCATAN ACROSS THE FLORIDA PENINSULA. THIS MOIST ONSHORE FLOW REGIME FAVORS NIGHT/MORNING CONVECTION ALONG THE COAST WITH AFTERNOON STORMS SHIFTING TO THE INTERIOR AND WEST COAST. THERE HAS BEEN JUST A LITTLE CONVECTION AROUND GRAND BAHAMA EARLY THIS MORNING SO HAVE LOWERED COASTAL POPS CONSIDERABLY FROM OUR CURRENT 60-70 PERCENT VALUES. THE LATEST MOS POPS ARE ONLY AROUND 40 PERCENT AREAWIDE. THIS SEEMS TOO LOW FOR THE INTERIOR SINCE MID LEVEL TEMPS ARE FORECAST TO REMAIN QUITE COOL (MINUS 9-10 DEGREES AT 500 MB). NEVERTHELESS...WILL ONLY GO A LITTLE ABOVE MOS POPS FOR THE INTERIOR. THINK THAT THE STRONGEST BOUNDARY INTERACTIONS WILL SHIFT FURTHER WEST TODAY AS EAST COAST SEA BREEZE PUSHES ACROSS THE PENINSULA A LITTLE QUICKER THAN YESTERDAY. GREATEST CHANCE FOR STRONG-SEVERE STORMS SHOULD BE IN THE FAR INTERIOR NORTHWEST. TONIGHT...ONSHORE FLOW WILL BE WEAK SO THE PROSPECTS FOR CONVECTION ALONG THE COAST WILL BE LOW AND MAINLY IN THE SOUTH. EXPECT EVENING CONVECTION WILL MAINLY SHIFT INTO WEST CENTRAL FLORIDA. THEREFORE WILL ONLY CARRY AN AREAWIDE 20 PERCENT POP. THU-TUE...RIDGE OF HIGH PRESSURE EXTENDING FROM THE WESTERN ATLANTIC (SARGASSO SEA) ACROSS CENTRAL FLORIDA AND INTO THE EASTERN GULF ON THURSDAY DROPS DOWN TO SOUTHERN FLORIDA SUNDAY AND REMAINS SOUTH OF THE AREA MONDAY AND TUESDAY AS A COOL FRONT SLOWLY MOVES ACROSS THE DEEP SOUTH. POSITION OF THE RIDGE AXIS WILL KEEP WINDS OUT OF THE SOUTHWEST FROM CAPE CANAVERAL NORTHWARD AND ONSHORE SOUTH OF THE CAPE THROUGH THE WEEKEND THEN UNIFORMLY SOUTHWEST/OFFSHORE MONDAY AND TUESDAY. WITH AN OFFSHORE FLOW PINNING STORMS TO THE EAST COAST FEEL THAT A 30 POP EVENING POP MORE APPROPRIATE FOR THE COASTAL AND NEARSHORE WATERS MONDAY/TUESDAY RATHER THAN THE STOCK/STANDARD 20 PERCENT/ISOLATED EARLY EVENING STORMS. DAYTIME HIGH TEMPERATURES SHOULD REACH THEIR CLIMO VALUES UPPER 80S/LOWER 90S BEFORE SKIES CLOUD OVER WITH MID/UPPER CLOUDINESS FROM THE STORMS. && .AVIATION...SIMILAR PATTERN TO YESTERDAY EXCEPT THAT SEA BREEZE WILL PUSH INLAND A LITTLE FASTER. HAVE SHORT TEMPO GROUPS FOR INLAND TERMINALS BUT STRONGEST STORMS THAT OCCUR DUE TO INTERACTION OF EAST/WEST COAST BOUNDARIES SHOULD BE WEST OF THE TERMINALS... EXCEPT MAYBE FOR KLEE. HAVE SHORT PROB30 GROUPS DURING THE EARLY AFTERNOON ALONG THE COAST...BUT AGAIN LIKE YESTERDAY...THINK THAT MID/HIGH CLOUDS WILL DELAY HEATING SLIGHTLY AND CONVECTIVE INITIATION SHOULD BE JUST INLAND OF THE COASTAL TERMINALS. && .MARINE...THROUGH TONIGHT THERE WILL BE A SLIGHT INCREASE IN ONSHORE FLOW EXCEPT NEAR THE LOW LEVEL RIDGE AXIS IN THE NORTH WHERE WINDS SHOULD CONTINUE AROUND 5 KNOTS. STILL SEA HEIGHTS SHOULD BE 3 FEET OR LESS. EXPECT SOME CONVECTION TO FORM ESPECIALLY ACROSS THE SOUTH BUT COVERAGE NOT MORE THAN SCATTERED. THU-SUN...WITH SURFACE-700MB RIDGE AXIS LYING OVER THE AREA EXPECT LIGHT WINDS WITH A SEA BREEZE COMPONENT EACH AFTERNOON. SEAS SHOULD BE NO MORE THAN 4 FEET OFFSHORE. && .PRELIMINARY POINT TEMPS/POPS... DAB 91 71 88 72 / 30 20 50 20 MCO 91 74 91 73 / 50 20 50 20 MLB 89 75 89 73 / 30 20 40 20 VRB 89 73 90 74 / 30 20 40 20 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. && $$ SHORT TERM/AVIATION...LASCODY LONG TERM....WIMMER fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1250 PM CDT THU JUN 26 2008 .DISCUSSION... ISSUED 1041 AM CDT THU JUN 26 2008 RATHER COMPLICATED SFC PATTERN THIS MORNING WITH SEVERAL MESOSCALE FEATURES ON THE MAP. DECAYING MCS IS MOVING SOUTHWARD ACROSS CENTRAL MISSOURI...WHILE ANOTHER MATURE MCS ROLLS ACROSS CENTRAL IOWA. MEANWHILE...LEFTOVER MCV WAS CENTERED JUST EAST OF KBMI... WITH A BOUNDARY ARCING JUST WEST OF KCMI DOWN TO NEAR KTAZ. WITH WARM/MOIST BOUNDARY LAYER AND MOSTLY SUNNY SKIES AHEAD OF THE MCV AND ATTENDANT BOUNDARY...CANNOT OUTRULE SCATTERED CONVECTION DEVELOPING ACROSS THE FAR EAST AND SOUTHEAST THIS AFTERNOON. MCS OVER IOWA SEEMS LIKELY TO TAKE A DIVE TO THE SOUTH LIKE THE PREVIOUS MCS DID...PERHAPS JUST GRAZING OUR FAR WESTERN COUNTIES THIS AFTERNOON. RUC ANALYSIS INDICATES DISTINCT BUBBLE OF STABLE AIR OVER ILLINOIS...WHILE INSTABILITY AXIS ARCS FROM NORTHWESTERN IOWA INTO SOUTHERN MISSOURI...REMAINING JUST WEST OF THE MISSISSIPPI RIVER. IOWA MCS WILL MOSTLY LIKELY TEND TO DRIFT ESE WITH THE MID-LEVEL FLOW...THEN PROPAGATE SOUTHWARD ALONG THE INSTABILITY AXIS... WHILE DECAYING SHOWERS MAY DRIFT INTO THE WESTERN EDGE OF THE STABLE BUBBLE REGION. RESHAPED THE POP FORECAST CONSIDERING THESE FEATURES. ALSO COOLED TEMPS A FEW DEGREES IN THE WEST CONSIDERING MID/HIGH LEVEL CLOUD COVER FROM CONVECTION TO THE WEST. WILL HAVE NEW ZONES AND FRESH GRIDS OUT AROUND 11 AM. HARDIMAN && .AVIATION... ISSUED 1249 PM CDT THU JUN 26 2008 MOST TERMINALS WILL BE IN SOMETHING OF A DEAD ZONE BETWEEN SOUTHWARD SURGING MCS ACTIVITY WEST OF THE MISSISSIPPI RIVER... AND SCATTERED CONVECTION RE-DEVELOPING INVOF MCV AND TRAILING BOUNDARY ACROSS EAST CENTRAL ILLINOIS. ONE EXCEPTION MAY BE KCMI WHICH COULD SEE VCTS OVER THE NEXT 2-4 HOURS. HARDIMAN && .PREV DISCUSSION... ISSUED 330 AM CDT THU JUN 26 2008 MODELS HAVE NOT BEEN HANDLING MCS/MCV ACTIVITY VERY WELL DURING THE PAST FEW NIGHTS...SO CONFIDENCE IN FORECAST WHICH MAKES THIS FORECAST TRICKIER THAN NORMAL. CURRENT MCS/MCV OVER NE MO/SE IA AND INTO CENTRAL IL WAS NOT DEPICTED BY MODELS. FORECAST CONCERN IS CONVECTION CHANCES AND SLIGHT RISK OF SEVERE STORMS THROUGH SAT. RADAR MOSAIC AND SATELLITE SHOWS A MCS/MCV OVER NE MO/SE IA AND INTO CENTRAL IL WITH LEADING EDGE OF CONVECTION ALONG I-55 WITH A THUNDERSTORM AS FAR EAST AS NORTHERN FORD COUNTY AND MOVING ESE. SEVERE WX THREAT APPEARS TO HAVE DIMINISHED OVER CENTRAL IL WHILE STRONGER LINE OF STORMS WAS PLOWING SOUTH TOWARD I-70 IN CENTRAL MO. STILL GETTING SOME THUNDERSTORMS WITH HEAVY RAINS ALONG THE IL RIVER AND JUST NORTH OF SPRINGFIELD. 08Z/3 AM SURFACE MAP SHOWS 1007 MB LOW PRESSURE OVER EASTERN LAKE SUPERIOR WITH A FRONTAL BOUNDARY EXTENDING THROUGH CENTRAL WI...NORTHERN IA AND CENTRAL NEBRASKA. MUGGY DEWPOINTS IN THE MID TO UPPER 60S WHILE TEMPS WERE IN THE LOW TO MID 70S. ALOFT A LARGE UPPER LEVEL HIGH PRESSURE RIDGE WAS SPRAWLED ACROSS THE SOUTHERN STATES WHILE UPPER LEVEL LOW/TROF OVER CANADA. SHORT WAVE TROF WAS OVER NW IL INTO MO WHERE MCS/MCV WAS. ANOTHER ONE WAS OVER OHIO AND YET ANOTHER OVER THE DAKOTAS. SHORT TERM...TODAY THROUGH SATURDAY. CONVECTION FROM MCS TO WEAKEN DURING THIS MORNING OVER CENTRAL IL LIKE IT DID YESTERDAY MORNING. BUT MCV FROM THIS MCS WILL DRIFT INTO EASTERN/NE IL AND INDIANA AND WILL DEVELOP SCATTERED CONVECTION THIS AFTERNOON IN UNSTABLE AIR MASS SO KEPT 30 TO 40% CHANCE OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON. HIGHS TODAY IN THE UPPER 80S TO AROUND 90F WITH LOWER 90S IN SE IL WHERE MORE SUNSHINE EXPECTED LIKE YESTERDAY. HUMID WITH DEWPOINTS IN THE UPPER 60S AND LOWER 70S. ANOTHER MCS TO DEVELOP TONIGHT OVER IA/NORTHERN IL AND MOVE ESE AND GOOD CHANCE IT WILL AFFECT AREAS ALONG AND NORTH OF I-74. SPC HAS SLIGHT RISK OF SEVERE STORMS NORTH OF A SPRINGFIELD TO PARIS LINE TONIGHT. HEAVY RAINS AND FREQUENT LIGHTNING FROM THUNDERSTORMS AS WELL. CONVECTION CHANCES INCREASE AGAIN FRI AFTERNOON ESPECIALLY NW OF I-55 AS UPPER LEVEL TROF AMPLIFIES/DIGS INTO THE MIDWEST AND DRIVES A COLD FRONT SE INTO NW IL BY MIDNIGHT FRI NIGHT. HIGHS AGAIN IN THE UPPER 80S WITH LOWER 90S SE IL AND HUMID WITH DEWPOINTS IN THE UPPER 60S/LOWER 70S. LIKELY CHANCE OF CONVECTION FRI NIGHT NW OF I-70. SPC HAS IL IN SLIGHT RISK FRI NIGHT WHILE GREAT RISK OF SEVERE STORMS OVER CENTRAL/NW IL ALONG AND NW OF A DANVILLE TO TAYLORVILLE LINE. HAVE FRONT COLLIDING WITH A VERY UNSTABLE AIR MASS WITH CAPES PEAKING FROM 2000 TO 4000 J/KG. COULD BE WIDESPREAD SEVERE HAIL/WINDS FRI NIGHT ESPECIALLY FRI EVENING WITH TORNADO THREAT MORE OVER NORTHERN IL WHERE MORE FAVORABLE STRONGER WIND FIELDS. COLD FRONT SLIDES SE THROUGH CENTRAL IL AFTER MIDNIGHT FRI NIGHT AND THRU SE IL SAT. BEST CHANCES OF CONVECTION SHIFT INTO EASTERN/SE IL SAT WHERE SPC HAS SLIGHT RISK OF SEVERE. SHOWERS TO END OVER THE IL RIVER VALLEY SAT AFTERNOON. A BIT COOLER HIGHS IN THE LOW TO MID 80S BUT RATHER HUMID YET WITH DEWPOINTS IN THE 60S. LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY. EXTENDED MODELS SHOW UPPER LEVEL LOW SETTLING INTO THE GREAT LAKES THIS WEEKEND AND OVER NORTHERN LOWER MI SUNDAY. IT NOW APPEARS CLOSE ENOUGH TO CENTRAL IL TO PRODUCE ISOLATED SHOWERS AND THUNDERSTORMS SUNDAY AFTERNOON. UPPER LEVEL LOW TRACKS SLOWLY EAST MON/TUE WITH DRY WX EXPECTED OVER CENTRAL/SE IL AND LESS HUMID AIR MASS. COOLED HIGHS A BIT THOUGH NOT QUITE AS COOL AS MEX/ECMWF HIGHS IN THE 70S SUN/MON. TEMPS WILL GRADUALLY MODIFY TUE/WED AS UPPER LEVEL LOW PULLS FURTHER AWAY FROM THE GREAT LAKES. HUETTL && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 855 PM CDT WED JUN 25 2008 .EVENING UPDATE OF PUBLIC FORECAST DISCUSSION... WILL BE ISSUING AN EVENING UPDATE OF ZFP PACKAGE. ONE CHG WILL BE TO UP DEW POINTS AS PER OBS AND FOLLOW WITH SLIGHT INCR IN FCST OVERNIGHT LOWS. LGT WSWLY SFC FLOW HAS ALLOWED DEW POINTS AT OR JUST ABOVE 70 DEG TO FILTER INTO WRN AND SRN PORTIONS OF FA. OF GREATER CONCERN THOUGH...ARE POPS/WX. WILL BE ADJUSTING OVERNIGHT POPS TO CURRENT RADAR/SATLT TRENDS. WITH LOSS OF DAYTIME HEATING...THREAT OF ISOLD TSTMS OVR FA HAS DIMINISHED. HOWEVER...TSTM COMPLEX CONTINUES TO EVOLVE OVR IA. LLVL WIND FIELD OVR NRN IL/NWRN IND IS FCST TO RMN UNFAVORABLE FOR CONTINUED DVLPMT INTO FA AS WINDS AOB H85 ARE FCST TO RMN LGT WNWLY OVERNIGHT...THEN BEGIN TO BACK INTO SW ON THUR. ALTHOUGH WIND PROFILES ARE NOT CONDUCIVE TO MCS PROPAGATING FWD ACROSS NRN IL/NWRN IND OVERNIGHT...AMS REMAINS QUITE UNSTABLE AND EXPECT SOME DISCRETE STMS TO FIRE ESEWD OF STNRY/BACKBUILDING COMPLEX OVR IA. THEREFORE HAVE BUMPED UP POPS OVR SWRN PORTION OF FA FOR OVERNIGHT. WILL KEEP CHC POPS RMNDR ARE FOR PRE DAWN HRS. MERZLOCK && .DISCUSSION... 247 PM CDT MAIN FORECAST CONCERNS WILL BE THREAT OF THUNDERSTORMS NEXT FEW DAYS. FAIRLY STRONG MESOSCALE CONVECTIVE VORT MOVING THROUGH CHICAGO AREA ATTM. EARLIER CONVECTION WITH THIS SYSTEM HAS LEFT A LOT OF LOW STRATUS WHICH HAS SEVERELY LIMITED INSOLATION AND DESTABILIZATION OVER NORTHERN IL. BEST LOW LEVEL INFLOW AND INSTABILITY IS WELL SOUTHEAST ACROSS PARTS OF N AND CENTRAL IN BACK INTO CENTRAL IL. COULD BE A FEW LINGERING SHOWERS OVER FAR SE SECTIONS OF FORECAST AREA EARLY THIS EVENING...OTHERWISE DRY MUCH OF THE AREA TONIGHT. NAM INDICATES ANOTHER MCS DEVELOPING OVER IA AND MOVING INTO N AND CENTRAL IL LATE TONIGHT OR THU MORNING. SATELLITE SHOWS ANOTHER CONVECTIVELY INDUCED VORT MOVING INTO NW IA ATTM...SO NAM SEEMS REASONABLE. LOW LEVEL JET SHOULD REFOCUS FROM NORTHERN KS INTO NORTHERN MO LATE TONIGHT TO SUPPORT THIS CONVECTION. MCS MAY BE DIMINISHING DIURNALLY AS IT GET INTO IL THU MORNING. WILL KEEP CHANCE POPS GOING FOR OVERNIGHT BUT CUT BACK TO 30-40 PERCENT...WITH HIGHEST POPS IN S AND W PART OF FORECAST AREA. BEYOND THU MORNING THINGS BECOME MURKY. PATTERN CONTINUES THU...THU NIGHT...AND FRI WITH VERY WARM TROPICAL AIR MASS IN PLACE. DEWPOINTS WILL BE AROUND 70 SO THIS IS SOME OF THE JUCIEST AIR OF THE SEASON. UPPER JET CONTINUES ACROSS THE NORTHERN TIER OF STATES INTO THE GREAT LAKES...SO SHEAR IS NOT VERY STRONG OVER THIS AREA...BUT INSTABILITY SUFFICIENT FOR STRONG TO SEVERE STORMS AND THE POTENTIAL FOR HAIL AND DAMAGING WINDS. PRECIPITABLE WATER VALUES OF 1.5 TO 2 INCHES. POTENTIAL EXISTS FOR SLOW MOVING AND/OR TRAINING STORMS. THUS THE POTENTIAL FOR HEAVY RAIN AND FLOODING EXISTS. THE QUESTION IS WHERE MCS BOUNDARIES AND SMALL SCALE SHORT WAVES WILL BE WHICH WILL AFFECT PLACEMENT AND TIMING OF THUNDERSTORM CLUSTERS THU THROUGH FRI..BUT WILL CONTINUE FAIRLY HIGH CHANCE OR LIKELY CATEGORY POPS THROUGH THIS PERIOD. VIGOROUS SHORT WAVE WILL MOVE ACROSS US/CAN BORDER AND WILL EVENTUALLY FORM CUT OFF LOW OVER GREAT LAKES BY THE END OF THE WEEK. THIS WILL PUSH A COLD FRONT THROUGH THE AREA FRIDAY NIGHT...BRINGING AN END TO THE SEVERE AND HEAVY RAIN THREAT. AS UPPER LOW WOBBLES SEWD ACROSS THE GREAT LAKES PERIODS OF SHOWERY WEATHER ARE POSSIBLE THROUGH THE WEEKEND. THIS WILL BE FOLLOWED BY A DRY AND MILD PERIOD THROUGH MID WEEK. ALLSOPP && .AVIATION... 658 PM CDT FOR 00Z TAFS...FEW CHANGES FROM 18Z FORECAST THINKING WITH CONVECTIVE TRENDS/PROBABILITIES MAIN QUESTION NEXT 24 HOURS. SHORT WAVE/MCV CLEARLY EVIDENT IN VAPOR IMAGERY MOVING OFF TO THE EAST OF THE FORECAST AREA EARLY THIS EVENING...WITH SUBSIDENCE ACROSS FORECAST AREA IN WAKE OF THIS FEATURE. LOOKING AT A FEW ACARS ASCENT/DECENT SOUNDINGS FROM KORD APPEARS TO BE A WARM BULGE AROUND 800 HPA CAPPING OTHERWISE WARM/MOIST BOUNDARY LAYER...DESPITE VIS SATELLITE EVIDENCE OF LINGERING BOUNDARIES FROM MORNING/EARLY AFTERNOON MCS REMNANTS. FARTHER TO THE WEST...CONVECTION DEVELOPING ACROSS PORTIONS OF CENTRAL IOWA AHEAD OF ANOTHER WEAK MID LEVEL SHORT WAVE AND ALONG/AHEAD OF SURFACE FRONTAL BOUNDARY ACROSS WESTERN PART OF THE HAWKEYE STATE. SPC RUC MESOANALYSIS DATA INDICATES IMPRESSIVE INSTABILITY ACROSS CENTRAL/SOUTHERN IA AT THIS HOUR...WITH 4000-5000 J/KG OF MLCAPE SOUTH OF I/80 CORRIDOR. PROFILER WINDS SHOW STRONGER LOW LEVEL SOUTHERLY FLOW FARTHER WEST INTO SOUTHWEST IOWA/NEBRASKA...WITH MUCH WEAKER LOW LEVEL SUPPORT FARTHER NORTH/EAST. THUS EXPECT CONTINUED DEVELOPMENT FROM AROUND KDSM SOUTHWEST/WEST TOWARD KOMA VCNTY...WHILE AREA OF LIKELY MORE ELEVATED CONVECTION OVER NORTHERN IA EXPECTED TO WEAKEN. BEST LOW LEVEL JET/FORCING EXPECTED TO REMAIN ACROSS NEB/SDAK/WESTERN IA WITH MCS PROPAGATION OFF TO THE SOUTHEAST WHICH SHOULD KEEP THIS MAIN AREA OF CONVECTION SOUTHWEST OF TERMINALS OVERNIGHT. HOWEVER...DESPITE WEAK SUPPORT FARTHER NORTH...NAM/GFS BOTH INDICATE ELEVATED INSTABILITY OVERNIGHT WHICH MAY STILL ALLOW SOME WEAK CONVECTION/REMAINS OF NORTHERN IA ACTIVITY TO ENCROACH ON FORECAST AREA LATE TONIGHT. WILL CONTINUE TO MONITOR CONVECTIVE TRENDS TO OUR WEST THIS EVENING...THOUGH WITH LOW CONFIDENCE WILL MAINTAIN CURRENT VCSH MENTION AFTER ABOUT 09Z. MODELS MAINTAIN IDEA OF ANOTHER WEAK SHORT WAVE APPROACHING THE FORECAST AREA FROM THE WEST THURSDAY AFTERNOON...WITH COLD FRONT SAGGING ACROSS IL/WI BORDER REGION DURING AFTERNOON. WHILE UPPER FORCING APPEARS TO REMAIN FAIRLY WEAK...FORECAST SOUNDINGS DEPICT FAIRLY IMPRESSIVE INSTABILITY...WITH MLCAPE VALUES 2000-3500 J/KG ACROSS FORECAST AREA BY AFTERNOON. GFS/NGM INDICATE COMBINATION FRONT/LAKE BREEZE MAY SAG ACROSS CHI AREA LATE AFTERNOON WHICH MAY BECOME FOCUS FOR CONVECTIVE DEVELOPMENT...THOUGH NAM KEEPS FRONT OFF TO THE NORTH THROUGH 00Z FRI. CONFIDENCE REMAINS FAIRLY LOW AT THIS TIME...THOUGH HAVE GONE AHEAD AND ADDED PROB30 FOR TSRA THURSDAY AFTERNOON BASED ON MAGNITUDE OF INSTABILITY/VERY WEAK CAP. AS FOR WINDS...WEST/SOUTHWEST WINDS EARLY THIS EVENING SHOULD LOSE GUSTINESS AND BACK SLIGHTLY MORE SOUTHWEST OVERNIGHT AS BOUNDARY LAYER DECOUPLES. WEST/SOUTHWEST LOW LEVEL FLOW CONTINUES THURSDAY...PERHAPS BACKING MORE SOUTHWEST IN THE AFTERNOON IN RESPONSE TO LOW PRESSURE DEVELOPING TO OUR WEST OVER PLAINS. SOME QUESTION REMAINS ABOUT LOCATION OF WEAK COLD/STATIONARY FRONT WHICH SETTLES NEARBY BY LATE AFTERNOON...AND POTENTIAL FOR IT TO COMBINE WITH LAKE BREEZE BOUNDARY LATE IN THE DAY. THIS COULD RESULT IN EASTERLY COMPONENT TO SURFACE WIND DEVELOPING FOR KORD/KMDW...THOUGH CONFIDENCE FAIRLY LOW AT THIS TIME. RATZER && .MARINE... 200 PM...OVERALL FEW CHANGES FROM PREVIOUS FORECAST. LARGE HIGH PRESSURE WILL MOVE OFF THE SOUTHEAST U.S. COAST TONIGHT AND THURSDAY MORNING. LOW PRESSURE OVER NORTHERN MN WILL MOVE NORTHEAST ACROSS THE UPPER LAKES TONIGHT THEN ACROSS SOUTHERN QUEBEC THURSDAY. A WEAK RIDGE OF HIGH PRESSURE WILL MOVE ACROSS THE LAKES THURSDAY AFTERNOON/EVENING. WINDS WILL BECOME LIGHT AND VRB ACROSS THE LAKE DURING THIS TIME BUT A LARGE TROUGH OF LOW PRESSURE WILL DEVELOP ACROSS THE PLAINS THURSDAY AND THURSDAY NIGHT. THIS TROUGH WILL EVOLVE INTO A LARGE AREA OF LOW PRESSURE WHICH WILL SLOWLY MOVE EAST ACROSS THE NORTHERN LAKES FRIDAY AND SATURDAY. THIS LOW THEN BROADENS AND WEAKENS AS IT REMAINS OVER THE EASTERN LAKES SUNDAY AND MONDAY. THIS WILL LIKELY CAUSE A PROLONGED PERIOD OF WEST/NORTHWEST FLOW OVER THE WESTERN LAKES THROUGH MONDAY...THOUGH SPEEDS DON/T APPEAR TO BE TOO STRONG AT THIS POINT. CMS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 658 PM CDT WED JUN 25 2008 .DISCUSSION... 247 PM CDT MAIN FORECAST CONCERNS WILL BE THREAT OF THUNDERSTORMS NEXT FEW DAYS. FAIRLY STRONG MESOSCALE CONVECTIVE VORT MOVING THROUGH CHICAGO AREA ATTM. EARLIER CONVECTION WITH THIS SYSTEM HAS LEFT A LOT OF LOW STRATUS WHICH HAS SEVERELY LIMITED INSOLATION AND DESTABILIZATION OVER NORTHERN IL. BEST LOW LEVEL INFLOW AND INSTABILITY IS WELL SOUTHEAST ACROSS PARTS OF N AND CENTRAL IN BACK INTO CENTRAL IL. COULD BE A FEW LINGERING SHOWERS OVER FAR SE SECTIONS OF FORECAST AREA EARLY THIS EVENING...OTHERWISE DRY MUCH OF THE AREA TONIGHT. NAM INDICATES ANOTHER MCS DEVELOPING OVER IA AND MOVING INTO N AND CENTRAL IL LATE TONIGHT OR THU MORNING. SATELLITE SHOWS ANOTHER CONVECTIVELY INDUCED VORT MOVING INTO NW IA ATTM...SO NAM SEEMS REASONABLE. LOW LEVEL JET SHOULD REFOCUS FROM NORTHERN KS INTO NORTHERN MO LATE TONIGHT TO SUPPORT THIS CONVECTION. MCS MAY BE DIMINISHING DIURNALLY AS IT GET INTO IL THU MORNING. WILL KEEP CHANCE POPS GOING FOR OVERNIGHT BUT CUT BACK TO 30-40 PERCENT...WITH HIGHEST POPS IN S AND W PART OF FORECAST AREA. BEYOND THU MORNING THINGS BECOME MURKY. PATTERN CONTINUES THU...THU NIGHT...AND FRI WITH VERY WARM TROPICAL AIR MASS IN PLACE. DEWPOINTS WILL BE AROUND 70 SO THIS IS SOME OF THE JUCIEST AIR OF THE SEASON. UPPER JET CONTINUES ACROSS THE NORTHERN TIER OF STATES INTO THE GREAT LAKES...SO SHEAR IS NOT VERY STRONG OVER THIS AREA...BUT INSTABILITY SUFFICIENT FOR STRONG TO SEVERE STORMS AND THE POTENTIAL FOR HAIL AND DAMAGING WINDS. PRECIPITABLE WATER VALUES OF 1.5 TO 2 INCHES. POTENTIAL EXISTS FOR SLOW MOVING AND/OR TRAINING STORMS. THUS THE POTENTIAL FOR HEAVY RAIN AND FLOODING EXISTS. THE QUESTION IS WHERE MCS BOUNDARIES AND SMALL SCALE SHORT WAVES WILL BE WHICH WILL AFFECT PLACEMENT AND TIMING OF THUNDERSTORM CLUSTERS THU THROUGH FRI..BUT WILL CONTINUE FAIRLY HIGH CHANCE OR LIKELY CATEGORY POPS THROUGH THIS PERIOD. VIGOROUS SHORT WAVE WILL MOVE ACROSS US/CAN BORDER AND WILL EVENTUALLY FORM CUT OFF LOW OVER GREAT LAKES BY THE END OF THE WEEK. THIS WILL PUSH A COLD FRONT THROUGH THE AREA FRIDAY NIGHT...BRINGING AN END TO THE SEVERE AND HEAVY RAIN THREAT. AS UPPER LOW WOBBLES SEWD ACROSS THE GREAT LAKES PERIODS OF SHOWERY WEATHER ARE POSSIBLE THROUGH THE WEEKEND. THIS WILL BE FOLLOWED BY A DRY AND MILD PERIOD THROUGH MID WEEK. ALLSOPP && .AVIATION... 658 PM CDT FOR 00Z TAFS...FEW CHANGES FROM 18Z FORECAST THINKING WITH CONVECTIVE TRENDS/PROBABILITIES MAIN QUESTION NEXT 24 HOURS. SHORT WAVE/MCV CLEARLY EVIDENT IN VAPOR IMAGERY MOVING OFF TO THE EAST OF THE FORECAST AREA EARLY THIS EVENING...WITH SUBSIDENCE ACROSS FORECAST AREA IN WAKE OF THIS FEATURE. LOOKING AT A FEW ACARS ASCENT/DECENT SOUNDINGS FROM KORD APPEARS TO BE A WARM BULGE AROUND 800 HPA CAPPING OTHERWISE WARM/MOIST BOUNDARY LAYER...DESPITE VIS SATELLITE EVIDENCE OF LINGERING BOUNDARIES FROM MORNING/EARLY AFTERNOON MCS REMNANTS. FARTHER TO THE WEST...CONVECTION DEVELOPING ACROSS PORTIONS OF CENTRAL IOWA AHEAD OF ANOTHER WEAK MID LEVEL SHORT WAVE AND ALONG/AHEAD OF SURFACE FRONTAL BOUNDARY ACROSS WESTERN PART OF THE HAWKEYE STATE. SPC RUC MESOANALYSIS DATA INDICATES IMPRESSIVE INSTABILITY ACROSS CENTRAL/SOUTHERN IA AT THIS HOUR...WITH 4000-5000 J/KG OF MLCAPE SOUTH OF I/80 CORRIDOR. PROFILER WINDS SHOW STRONGER LOW LEVEL SOUTHERLY FLOW FARTHER WEST INTO SOUTHWEST IOWA/NEBRASKA...WITH MUCH WEAKER LOW LEVEL SUPPORT FARTHER NORTH/EAST. THUS EXPECT CONTINUED DEVELOPMENT FROM AROUND KDSM SOUTHWEST/WEST TOWARD KOMA VCNTY...WHILE AREA OF LIKELY MORE ELEVATED CONVECTION OVER NORTHERN IA EXPECTED TO WEAKEN. BEST LOW LEVEL JET/FORCING EXPECTED TO REMAIN ACROSS NEB/SDAK/WESTERN IA WITH MCS PROPAGATION OFF TO THE SOUTHEAST WHICH SHOULD KEEP THIS MAIN AREA OF CONVECTION SOUTHWEST OF TERMINALS OVERNIGHT. HOWEVER...DESPITE WEAK SUPPORT FARTHER NORTH...NAM/GFS BOTH INDICATE ELEVATED INSTABILITY OVERNIGHT WHICH MAY STILL ALLOW SOME WEAK CONVECTION/REMAINS OF NORTHERN IA ACTIVITY TO ENCROACH ON FORECAST AREA LATE TONIGHT. WILL CONTINUE TO MONITOR CONVECTIVE TRENDS TO OUR WEST THIS EVENING...THOUGH WITH LOW CONFIDENCE WILL MAINTAIN CURRENT VCSH MENTION AFTER ABOUT 09Z. MODELS MAINTAIN IDEA OF ANOTHER WEAK SHORT WAVE APPROACHING THE FORECAST AREA FROM THE WEST THURSDAY AFTERNOON...WITH COLD FRONT SAGGING ACROSS IL/WI BORDER REGION DURING AFTERNOON. WHILE UPPER FORCING APPEARS TO REMAIN FAIRLY WEAK...FORECAST SOUNDINGS DEPICT FAIRLY IMPRESSIVE INSTABILITY...WITH MLCAPE VALUES 2000-3500 J/KG ACROSS FORECAST AREA BY AFTERNOON. GFS/NGM INDICATE COMBINATION FRONT/LAKE BREEZE MAY SAG ACROSS CHI AREA LATE AFTERNOON WHICH MAY BECOME FOCUS FOR CONVECTIVE DEVELOPMENT...THOUGH NAM KEEPS FRONT OFF TO THE NORTH THROUGH 00Z FRI. CONFIDENCE REMAINS FAIRLY LOW AT THIS TIME...THOUGH HAVE GONE AHEAD AND ADDED PROB30 FOR TSRA THURSDAY AFTERNOON BASED ON MAGNITUDE OF INSTABILITY/VERY WEAK CAP. AS FOR WINDS...WEST/SOUTHWEST WINDS EARLY THIS EVENING SHOULD LOSE GUSTINESS AND BACK SLIGHTLY MORE SOUTHWEST OVERNIGHT AS BOUNDARY LAYER DECOUPLES. WEST/SOUTHWEST LOW LEVEL FLOW CONTINUES THURSDAY...PERHAPS BACKING MORE SOUTHWEST IN THE AFTERNOON IN RESPONSE TO LOW PRESSURE DEVELOPING TO OUR WEST OVER PLAINS. SOME QUESTION REMAINS ABOUT LOCATION OF WEAK COLD/STATIONARY FRONT WHICH SETTLES NEARBY BY LATE AFTERNOON...AND POTENTIAL FOR IT TO COMBINE WITH LAKE BREEZE BOUNDARY LATE IN THE DAY. THIS COULD RESULT IN EASTERLY COMPONENT TO SURFACE WIND DEVELOPING FOR KORD/KMDW...THOUGH CONFIDENCE FAIRLY LOW AT THIS TIME. RATZER && .MARINE... 200 PM...OVERALL FEW CHANGES FROM PREVIOUS FORECAST. LARGE HIGH PRESSURE WILL MOVE OFF THE SOUTHEAST U.S. COAST TONIGHT AND THURSDAY MORNING. LOW PRESSURE OVER NORTHERN MN WILL MOVE NORTHEAST ACROSS THE UPPER LAKES TONIGHT THEN ACROSS SOUTHERN QUEBEC THURSDAY. A WEAK RIDGE OF HIGH PRESSURE WILL MOVE ACROSS THE LAKES THURSDAY AFTERNOON/EVENING. WINDS WILL BECOME LIGHT AND VRB ACROSS THE LAKE DURING THIS TIME BUT A LARGE TROUGH OF LOW PRESSURE WILL DEVELOP ACROSS THE PLAINS THURSDAY AND THURSDAY NIGHT. THIS TROUGH WILL EVOLVE INTO A LARGE AREA OF LOW PRESSURE WHICH WILL SLOWLY MOVE EAST ACROSS THE NORTHERN LAKES FRIDAY AND SATURDAY. THIS LOW THEN BROADENS AND WEAKENS AS IT REMAINS OVER THE EASTERN LAKES SUNDAY AND MONDAY. THIS WILL LIKELY CAUSE A PROLONGED PERIOD OF WEST/NORTHWEST FLOW OVER THE WESTERN LAKES THROUGH MONDAY...THOUGH SPEEDS DON/T APPEAR TO BE TOO STRONG AT THIS POINT. CMS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 733 PM EDT THU JUN 26 2008 .AVIATION/UPDATE... TSRA ACTIVITY WHICH FORMED AHEAD OF MCV MOVG ESE ACROSS NRN INDIANA HAS MAINLY MOVED EAST OF THE AREA THIS EVE. STRATIFORM RAIN IN COMMA HEAD OF THIS VORTEX AFFECTING FWA ATTM SHOULD MOVE EAST OF THE TERMINAL BY ISSUANCE TIME. ISOLATED TSRA CONTG ALONG OUTFLOW BOUNDARIES AND POCKETS OF REMAINING INSTABILITY. VISIBLE LOOP SHOWING SKIES CLEARING NW OF MCV WITH WATER VAPOR LOOP ALSO INDICATING SUBSIDENCE ACROSS NW INDIANA/NE IL...THOUGH A FEW SHRA/TSRA ALSO HAVE DEVELOPED WITHIN THE CLEARING ZONE. THIS CONVECTIVE ACTIVITY TOO ISOLATED TO MENTION IN TAFS...BUT WILL KEEP AN ISOLATED STORM MENTIONED IN ZONES OVERNIGHT AS WK SHRTWV MOVG EAST FROM IA MAY HELP TRIGGER SOME CONVECTION BY LATE TONIGHT. WITH LIGHT WINDS AND SKIES GENERALLY BECOMING MAINLY CLEAR TONIGHT FOG SHOULD DEVELOP...ESPECIALLY IN AREAS WHICH HAD RAIN THIS AFTN WHICH WAS MOST OF THE CWA EXCEPT FAR NW. WILL ADD PATCHY FOG MENTION TO GRIDS/ZONES AND GO WITH MVFR VSBYS AT FWA FOR LATE TONIGHT AND EARLY FRIDAY. LOW PRESSURE EXPECTED TO MOVE EAST INTO THE UPPER MS VALLEY ON FRI WITH ASSOCIATED WARM FRONT LIFTING NE INTO NRN INDIANA. THIS SHOULD HELP TRIGGER TSRA IN THE AFTN AS DAYTIME HEATING SHOULD ONCE AGAIN RESULT IN VERY UNSTABLE CONDITIONS BY THAT TIME. && .PREV DISCUSSION... NEAR TERM... MAIN CONCERN IN NEAR TERM IS WITH TSTMS. MCV MOVG ACROSS NW INDIANA THIS AFTN. LAPS SFC BASED CAPES UP TO 4KJ/KG AHEAD OF THIS FEATURE. SFC TROF ALSO EVIDENT FM ERN MI SW TO WEST CENTRAL INDIANA. SCT TSTMS HAVE BEEN FORMING ALONG THIS BOUNDARY THIS AFTN. WITH WK SHEAR AND VERY MOIST/UNSTABLE ENVIRONMENT...STORMS WILL BE MARGINALLY SEVERE WITH GUSTY WINDS... VERY HEAVY RAIN.... AND SOME HAIL. EXPECT THIS ACTIVITY TO PERSIST INTO THE EVE ALONG SFC TROF AND SUBSEQUENT TSTM OUTFLOW BOUNDARIES SO HAVE CONTD WITH SCT POPS THROUGH 00Z SE WITH A CHC NW. FOR THE EVE HOURS INHERITED LIKELY POPS ACROSS THE NORTHERN COUNTIES. GFS WITH SUPPORT FROM RUC13 INDICATING AN AT LEAST PARTIALLY CONVECTIVELY ENHANCED SHRTWV WILL MOVE EAST FROM NW IA THIS AFTN TO ERN WI/NE IL BY 06Z. CURRENTLY MESO-BETA ELEMENTS ASSOCIATED WITH THIS FEATURE WERE MOVG SSE HWVR SOME CONVECTION ALSO PUSHING EAST ACROSS NRN IA. CAN`T RULE OUT MORE WIDESPREAD CONVECTION DVLPG AHEAD OF THIS SHRTWV AND MOVG INTO OUR AREA BY LATE EVE BUT GIVEN CURRENT TRENDS WITH CONVECTION UPSTREAM HAVE LOWERED POPS TO CHC ACROSS NRN PORTIONS OF CWA IN THE 00Z-06Z TIMEFRAME. SHORT TERM... LATE TONIGHT INTO FRIDAY AND FRIDAY NIGHT... MAIN CONCERN IS THE SVR WEATHER POTENTIAL FRI INTO FRI NIGHT IN ACTIVE PATTERN AS POTENT UPPER TROUGH DIGS INTO THE NRN PLAINS AND UPPER MIDWEST FRI INTO FRI NIGHT. LATE TONIGHT/FRI MORNING...LEFT IN CHC POPS FOR SHOWERS/STORMS AS FA MAY BE IMPACTED BY CONVECTION/MCS CURRENTLY BACK IN IA WITH FURTHER DEVELOPMENT EXPECTED IN THE IA/SRN WI/NW IL VICINITY TONIGHT. 12Z MODELS CONTINUE TO STRUGGLE WITH MESOSCALE DETAILS WITH THE GFS HAVING CONVECTIVE FEEDBACK ISSUES AND THE 12Z NAM INITIALIZING POORLY WITH QPF. HOWEVER...AM CONFIDENT THAT AN ADDITIONAL MCS WILL DEVELOP OUT TO THE W WITH INCREASING LL CONV AHEAD OF POTENT UPPER TROUGH ALONG THETA-E/MOISTURE GRADIENT. WOULD THINK THAT THIS WOULD TRACK EASTWARD FOLLOWING PROGGED CORFIDI VECTORS/7H FLOW. ALSO WOULD EXPECT THE MCS TO TRACK NEAR/JUST SOUTH OF STRONG INSTABILITY/THETA-E BOUNDARY FROM LOWER MICHIGAN WNW TOWARD THE IL/WI BORDER. WITH THIS SAID...THINK THIS FEATURE WILL WEAKEN AS IT OUTRUNS BETTER FORCING WITH TRACK/SPEED IN QUESTION DUE TO LACK OF ANY GOOD MODEL GUIDANCE. AS A RESULT...WILL KEEP WITH CHC POPS DURING THIS TIMEFRAME DUE TO CONTINUED UNCERTAINTY. FRIDAY AFTERNOON...DEPENDING ON EVOLUTION OF MCS RENMANTS IT ONCE AGAIN LOOKS LIKE THE ATMOSPHERE WILL BECOME VERY UNSTABLE AS STEEPENING MID LEVEL LAPSE RATES COMBINED WITH VERY MOIST LOW LEVELS WILL YIELD MLCAPES AOA 2500 J/KG. NO OBVIOUS TRIGGER FOR SHOWER/STORM DEVELOPMENT WITH TIGHT THETA-E GRADIENT/DIFFUSE SFC TROUGH RETREATING OFF TO THE NORTH IN REPONSE TO HEIGHT FALLS ACROSS THE NORTH CENTRAL US. IF INSTABILITY IS REALIZED THINK IT WILL BE ENOUGH TO BREAK WEAK CAP NEAR 12KFT FOR SCT SHOWERS/STORMS...ESPECIALLY WITH OUTFLOW BOUNDARIES AROUND. DEEP LAYER SHEAR NEEDED FOR ROTATING UPDRAFTS/SUPERCELLS WILL LIKELY STAY OFF TO THE WEST...HOWEVER...HAIL/MICROBURST MULTICELLS A DISTINT POSSIBLITY WITH IMPRESSIVE CAPE...STEEP LL LAPSE RATES...AND SOMEWHAT DRY MID-LEVELS. FRIDAY NIGHT...MORE ORGANIZED SHOWER/STORM ACTIVITY SHOULD INITIATE FRI AFTN ALONG AND JUST AHEAD OF A PRE-FRONTAL TROUGH FROM NEAR MCI NE THRU DSM AND GRB. THIS ACTIVITY WILL LIKELY START OUT AS DISCRETE SUPERCELLS AND THEN ORGANIZE INTO A COLD POOL DRIVEN SQUALL LINE/LEWP...POSSIBLY AFFECTING THE REGION FROM WEST TO EAST FRI NIGHT. SVR WX A CONCERN WITH THIS AS IT MOVES THROUGH. DO NOT EXPECT THIS TO FALL APART AS WE LOSE DAYTIME HEATING DUE TO LARGE SCALE FORCING WITH DIFF PVA/HEIGHT FALLS...DIFFLUENT FLOW ALOFT IN RIGHT ENTRANCE REGION OF 100KT JET ROUNDING BASE OF TROUGH...AND LL CONV ALONG SFC TROUGH/OUTFLOW. CONTINUED WITH LIKELY POPS FOR FRIDAY NIGHT AND INCLUDED A SEVERE MENTION IN THE GRIDS. HEAVY RAIN DEFINITELY POSSIBLE FRIDAY INTO FRIDAY NIGHT WITH PWATS INCREASING TO NEAR 2 INCHES AND A DEEP WARM CLOUD LAYER NEAR 10KFT. LONG TERM... LITTLE CHANGE TO LONG TERM WITH OVERALL PACKAGE IN GOOD SHAPE. UNSETTLED WEATHER ON TAP FOR SATURDAY AFTERNOON WITH FRONTAL PASSAGE AND AGAIN ON SUNDAY WITH COLD AIR ALOFT AND MID LEVEL SHORTWAVE. MODELS ARE FAIRLY USELESS ON DETAILS FOR SATURDAY WITH THE NEAR TERM SO MUDDLED THAT INITIALIZATION ISSUES ABOUND. BUT THE LARGER DETAILS ARE STILL CONSISTENT SHOWING UPPER LOW SETTLING OVER GREAT LAKES AND ASSOC SFC FRONT ROLLING THROUGH ON SATURDAY AFTERNOON. MOISTURE/INSTABILITY SHOWN BY BUFR SOUNDINGS TO BE WELL ESTABLISHED AHEAD OF THE BNDRY. WHILE ACTIVITY COULD FIRE EARLY ALONG PRE FRONTAL TROF INDICATED BY NAM IT WILL LIKELY TURN OUT...AS HAS BEEN THE CASE IN RECENT DAYS...THAT DETAILS OF THE AFTERNOON EVOLUTION WILL BE LARGELY DEPENDENT ON FEATURES REMAINING FROM FRIDAY NIGHTS ACTIVITY TO THE WEST. COLD POOL THEN SETTLES IN WITH MODELS POORLY HANDLING STRENGTH AND LOCATION FROM RUN TO RUN WITH LARGE TIMING DIFFERENCES ON H5 SHORTWAVE ROTATING AROUND LOW. KEPT AFTERNOON POPS INTACT AND DID NOT ADD ANYTHING IN MORNING HOURS DUE TO LOW CONFIDENCE. DEEP LOW OVER EASTERN NA LIFTS WITH BROADER TROFING IN ITS WAKE KEEPING AREA UNDER UPPER NW FLOW THROUGH THE WEEK. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...STEINWEDEL LONG TERM...LUDINGTON AVIATION...TAYLOR NEAR TERM...TAYLOR in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 323 PM EDT THU JUN 26 2008 .NEAR TERM... MAIN CONCERN IN NEAR TERM IS WITH TSTMS. MCV MOVG ACROSS NW INDIANA THIS AFTN. LAPS SFC BASED CAPES UP TO 4KJ/KG AHEAD OF THIS FEATURE. SFC TROF ALSO EVIDENT FM ERN MI SW TO WEST CENTRAL INDIANA. SCT TSTMS HAVE BEEN FORMING ALONG THIS BOUNDARY THIS AFTN. WITH WK SHEAR AND VERY MOIST/UNSTABLE ENVIRONMENT...STORMS WILL BE MARGINALLY SEVERE WITH GUSTY WINDS... VERY HEAVY RAIN.... AND SOME HAIL. EXPECT THIS ACTIVITY TO PERSIST INTO THE EVE ALONG SFC TROF AND SUBSEQUENT TSTM OUTFLOW BOUNDARIES SO HAVE CONTD WITH SCT POPS THROUGH 00Z SE WITH A CHC NW. FOR THE EVE HOURS INHERITED LIKELY POPS ACROSS THE NORTHERN COUNTIES. GFS WITH SUPPORT FROM RUC13 INDICATING AN AT LEAST PARTIALLY CONVECTIVELY ENHANCED SHRTWV WILL MOVE EAST FROM NW IA THIS AFTN TO ERN WI/NE IL BY 06Z. CURRENTLY MESO-BETA ELEMENTS ASSOCIATED WITH THIS FEATURE WERE MOVG SSE HWVR SOME CONVECTION ALSO PUSHING EAST ACROSS NRN IA. CAN`T RULE OUT MORE WIDESPREAD CONVECTION DVLPG AHEAD OF THIS SHRTWV AND MOVG INTO OUR AREA BY LATE EVE BUT GIVEN CURRENT TRENDS WITH CONVECTION UPSTREAM HAVE LOWERED POPS TO CHC ACROSS NRN PORTIONS OF CWA IN THE 00Z-06Z TIMEFRAME. && .SHORT TERM... LATE TONIGHT INTO FRIDAY AND FRIDAY NIGHT... MAIN CONCERN IS THE SVR WEATHER POTENTIAL FRI INTO FRI NIGHT IN ACTIVE PATTERN AS POTENT UPPER TROUGH DIGS INTO THE NRN PLAINS AND UPPER MIDWEST FRI INTO FRI NIGHT. LATE TONIGHT/FRI MORNING...LEFT IN CHC POPS FOR SHOWERS/STORMS AS FA MAY BE IMPACTED BY CONVECTION/MCS CURRENTLY BACK IN IA WITH FURTHER DEVELOPMENT EXPECTED IN THE IA/SRN WI/NW IL VICINITY TONIGHT. 12Z MODELS CONTINUE TO STRUGGLE WITH MESOSCALE DETAILS WITH THE GFS HAVING CONVECTIVE FEEDBACK ISSUES AND THE 12Z NAM INITIALIZING POORLY WITH QPF. HOWEVER...AM CONFIDENT THAT AN ADDITIONAL MCS WILL DEVELOP OUT TO THE W WITH INCREASING LL CONV AHEAD OF POTENT UPPER TROUGH ALONG THETA-E/MOISTURE GRADIENT. WOULD THINK THAT THIS WOULD TRACK EASTWARD FOLLOWING PROGGED CORFIDI VECTORS/7H FLOW. ALSO WOULD EXPECT THE MCS TO TRACK NEAR/JUST SOUTH OF STRONG INSTABILITY/THETA-E BOUNDARY FROM LOWER MICHIGAN WNW TOWARD THE IL/WI BORDER. WITH THIS SAID...THINK THIS FEATURE WILL WEAKEN AS IT OUTRUNS BETTER FORCING WITH TRACK/SPEED IN QUESTION DUE TO LACK OF ANY GOOD MODEL GUIDANCE. AS A RESULT...WILL KEEP WITH CHC POPS DURING THIS TIMEFRAME DUE TO CONTINUED UNCERTAINTY. FRIDAY AFTERNOON...DEPENDING ON EVOLUTION OF MCS RENMANTS IT ONCE AGAIN LOOKS LIKE THE ATMOSPHERE WILL BECOME VERY UNSTABLE AS STEEPENING MID LEVEL LAPSE RATES COMBINED WITH VERY MOIST LOW LEVELS WILL YIELD MLCAPES AOA 2500 J/KG. NO OBVIOUS TRIGGER FOR SHOWER/STORM DEVELOPMENT WITH TIGHT THETA-E GRADIENT/DIFFUSE SFC TROUGH RETREATING OFF TO THE NORTH IN REPONSE TO HEIGHT FALLS ACROSS THE NORTH CENTRAL US. IF INSTABILITY IS REALIZED THINK IT WILL BE ENOUGH TO BREAK WEAK CAP NEAR 12KFT FOR SCT SHOWERS/STORMS...ESPECIALLY WITH OUTFLOW BOUNDARIES AROUND. DEEP LAYER SHEAR NEEDED FOR ROTATING UPDRAFTS/SUPERCELLS WILL LIKELY STAY OFF TO THE WEST...HOWEVER...HAIL/MICROBURST MULTICELLS A DISTINT POSSIBLITY WITH IMPRESSIVE CAPE...STEEP LL LAPSE RATES...AND SOMEWHAT DRY MID-LEVELS. FRIDAY NIGHT...MORE ORGANIZED SHOWER/STORM ACTIVITY SHOULD INITIATE FRI AFTN ALONG AND JUST AHEAD OF A PRE-FRONTAL TROUGH FROM NEAR MCI NE THRU DSM AND GRB. THIS ACTIVITY WILL LIKELY START OUT AS DISCRETE SUPERCELLS AND THEN ORGANIZE INTO A COLD POOL DRIVEN SQUALL LINE/LEWP...POSSIBLY AFFECTING THE REGION FROM WEST TO EAST FRI NIGHT. SVR WX A CONCERN WITH THIS AS IT MOVES THROUGH. DO NOT EXPECT THIS TO FALL APART AS WE LOSE DAYTIME HEATING DUE TO LARGE SCALE FORCING WITH DIFF PVA/HEIGHT FALLS...DIFFLUENT FLOW ALOFT IN RIGHT ENTRANCE REGION OF 100KT JET ROUNDING BASE OF TROUGH...AND LL CONV ALONG SFC TROUGH/OUTFLOW. CONTINUED WITH LIKELY POPS FOR FRIDAY NIGHT AND INCLUDED A SEVERE MENTION IN THE GRIDS. HEAVY RAIN DEFINITELY POSSIBLE FRIDAY INTO FRIDAY NIGHT WITH PWATS INCREASING TO NEAR 2 INCHES AND A DEEP WARM CLOUD LAYER NEAR 10KFT. && .LONG TERM... LITTLE CHANGE TO LONG TERM WITH OVERALL PACKAGE IN GOOD SHAPE. UNSETTLED WEATHER ON TAP FOR SATURDAY AFTERNOON WITH FRONTAL PASSAGE AND AGAIN ON SUNDAY WITH COLD AIR ALOFT AND MID LEVEL SHORTWAVE. MODELS ARE FAIRLY USELESS ON DETAILS FOR SATURDAY WITH THE NEAR TERM SO MUDDLED THAT INITIALIZATION ISSUES ABOUND. BUT THE LARGER DETAILS ARE STILL CONSISTENT SHOWING UPPER LOW SETTLING OVER GREAT LAKES AND ASSOC SFC FRONT ROLLING THROUGH ON SATURDAY AFTERNOON. MOISTURE/INSTABILITY SHOWN BY BUFR SOUNDINGS TO BE WELL ESTABLISHED AHEAD OF THE BNDRY. WHILE ACTIVITY COULD FIRE EARLY ALONG PRE FRONTAL TROF INDICATED BY NAM IT WILL LIKELY TURN OUT...AS HAS BEEN THE CASE IN RECENT DAYS...THAT DETAILS OF THE AFTERNOON EVOLUTION WILL BE LARGELY DEPENDENT ON FEATURES REMAINING FROM FRIDAY NIGHTS ACTIVITY TO THE WEST. COLD POOL THEN SETTLES IN WITH MODELS POORLY HANDLING STRENGTH AND LOCATION FROM RUN TO RUN WITH LARGE TIMING DIFFERENCES ON H5 SHORTWAVE ROTATING AROUND LOW. KEPT AFTERNOON POPS INTACT AND DID NOT ADD ANYTHING IN MORNING HOURS DUE TO LOW CONFIDENCE. DEEP LOW OVER EASTERN NA LIFTS WITH BROADER TROFING IN ITS WAKE KEEPING AREA UNDER UPPER NW FLOW THROUGH THE WEEK. && .PREV DISCUSSION... /ISSUED 131 PM EDT THU JUN 26 2008/ AVIATION... THUNDERSTORMS HAVE DEVELOPED OVER THE WESTERN AND SOUTHERN PORTIONS OF THE FORECAST AREA. THESE SHOULD NOT IMPACT KSBN UNTIL MID AFTERNOON BUT WILL TRACK NORTHEAST TOWARDS KFWA. MORE DEVELOPMENT UPSTREAM OVER IOWA WILL PROPAGATE TOWARDS THE REGION WITH POTENTIAL AFFECTS ON TERMINALS OVERNIGHT INTO FRIDAY MORNING. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...STEINWEDEL LONG TERM...LUDINGTON AVIATION...LUDINGTON NEAR TERM...TAYLOR in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 154 PM EDT WED JUN 25 2008 .UPDATE/AVIATION... GRIDS/ZONES...WILL LET SCT POPS RIDE FOR THE TIME BEING FOR THE AFTERNOON. AREA OF SHOWERS IS WORKING EAST WHICH WILL AFFECT MAINLY SOUTHERN PORTIONS OF THE FORECAST AREA. BIG QUESTIONS REMAINS IF THE ATMOSPHERE CAN RECOVER SUFFICIENTLY AND FAST ENOUGH TO ALLOW FOR ADDITIONAL STORMS TO DEVELOP IN ASSOCIATION WITH THE APPROACHING MCV. IR SAT SHOWING GENERALLY WARMING CLOUD TOPS AND NO REAL SIGNS OF ANYTHING TO KEY IN ON. POCKETS OF CLEARING JUST HEAD OF THE MCV HAVE ALLOWED A FEW AREAS TO CLIMB BACK TOWARDS 80. WILL CONTINUE TO MONITOR TRENDS BUT NO FURTHER UPDATES ANTICIPATED ATTM PRIOR TO AFTERNOON PACKAGE ISSUANCE. AVIATION WISE...FIRST BATCH OF PRECIP HAS CLEARED BOTH SITES LEAVING BEHIND VFR CONDITIONS AGAIN. HAVE WENT RATHER CONSERVATIVE AT BOTH SITES THROUGH 00Z WITH MORE OF A VCSH MENTION. PROXIMITY OF INITIAL PRECIP TO KSBN DID APPEAR TO WARRANT A BRIEF TEMPO GROUP. TONIGHT MORE THAN LIKELY WILL BE DRY FOR MUCH OF THE AREA UNTIL TOWARDS MORNING WITH NEXT MCS MOVING IN. WILL KEEP HIGH AND DRY FOR NOW. && PREV DISCUSSION... /ISSUED 416 AM EDT WED JUN 25 2008/ SHORT TERM... TODAY THROUGH THURSDAY NIGHT VERY COMPLICATED FORECAST IN STORE FOR THE PERIOD. CONCERNS ON CLOUD COVER/CONVECTIVE INFLUENCES/AND STRENGTH OF MID LEVEL COOLING ARE ABOUND. CONVECTIVE COMPLEX OVER MO/IL IS BEING SUPPORTED BY A MID LEVEL IMPULSE AND ASSOCIATED LLJ. THIS IMPULSE IS SLOWLY PUSHING EAST TOWARD THE FA. LARGE SCALE ASCENT AND INCREASED LL FLOW PER PROFILER DATA...UNDER STEEPENING MID LEVEL LAPSE RATES IS SUPPORTING SCT SHRA/TS DEVELOPMENT OVER NE IL. EXPECTING THIS AREA OF SHOWERS AND THUNDERSTORMS TO CONTINUE INTO THE FA THROUGH MORNING. TODAY...HAVE UTILIZED THE NGM FOR SYNOPTIC STRUCTURE AS THE GFS/NAM/RUC ALL SUFFER GREATLY FROM CONVECTIVE FEEDBACK AND OTHER BIAS ISSUES. EXPECTING THE MID LEVEL IMPULSE DEPICTED ON WATER VAPOR OVER SOUTHERN IA TO SLOWLY PUSH EAST INTO THE FA. ROBUST CONVECTION/LATENT HEAT RELEASE UPSTREAM WILL FURTHER ENHANCE LL PV FIELDS AND HELP IN THE MAINTENANCE AND PROPAGATION OF THIS IMPULSE OVER THE REGION TODAY. GROWING INSTABILITY PER MID LEVEL COOLING AND ADDED LL MOISTURE WILL SUPPORT CONVECTION THROUGH MOST OF THE DAY...TRANSITIONING EAST THROUGH THE DAY. CLOUD COVER IS EXPECTED TO HIGHLY LIMIT SOLAR INSOLATION OVER NW THIRD OF THE FA...THUS LIMITING INSTABILITY. BEST CHANCE FOR STRONG/SEVERE STORMS WILL BE EAST IF ENOUGH SUN IS REALIZED...WHICH WOULD SUPPORT NEARLY 2000 J/KG CAPE AND PULSE WIND/HAIL THREAT. HOWEVER...CONVECTIVE OUTFLOW AND CLOUD COVER MAY HIGHLY LIMIT TEMPS AND FEEL SEVERE WORDING IS NOT PRUDENT ATTM. TEMPS IN THE GRIDS ARE LIKELY STILL TOO WARM. HAVE LOWERED SOME ALREADY...AND THINGS MAY NEED TO BE LOWERED MORE. IT IS ENTIRELY POSSIBLE THAT A MAJORITY OF THE FA MAY NOT SURPASS THE LOW TO MID 70S. LEAD SW WILL EXIT THE REGION TONIGHT. CONVECTIVE OUTFLOW MODIFIED FRONTAL BOUNDARY OVER IA/MN IS EXPECTED TO BE THE INITIATION POINT OF NEW VIGOROUS CONVECTION THIS AFTERNOON/EVENING. HAVE RETAINED POP MENTION FOR A POSSIBLE MCS PROPAGATING INTO THE FA TONIGHT. THETA-E RIDGING PER 305 K MIXING RATIO PROGS WOULD SUPPORT PROPAGATION OF THIS SYSTEM INTO THE REGION...WITH THE BEST CHANCE FOR TS RESIDING IN NW. THUR...FLATTENING ACTIVE NW FLOW WILL SEND ANOTHER MID LEVEL DISTURBANCE INTO THE REGION ALONG A STALLED FRONTAL BOUNDARY TO THE NORTH. THIS FITS THE MCS/DERECHO PATTERN WELL FOR THE AREA...ESPECIALLY WITH LL MOISTURE AND HEAT IN PLACE. HAVE RETAINED 50 POP MENTION IN THE NORTH...TRENDING TO 30 SOUTH WHERE MID LEVEL WARMING/CAPPING MAY LIMIT CONVECTIVE POTENTIAL. OTHERWISE...HAVE RAISED HIGHS A FEW DEGREES GIVEN SOUTHERLY/DEEP MIXED FLOW. H85 TEMPS AROUND 17C WOULD SPELL MID 80S EASILY FOR MOST OF THE FA. LONG TERM... BRIEF RESPITE TO PNA PATTN ACRS NOAM WILL BREAK TWD SIG AMPLIFICATION ONCE AGAIN BY NXT WEEKEND IN RESPONSE TO SERIES OF FAST MOVING EMBEDDED SW/S WITHIN SEASONABLY STRONG WESTERLY FLW AND DEEP GULF OF AK STORM MOVING INTO WRN CANADA. DIFFICULT TO TIME SW TROUGHS AS SEEN W/INCONSISTENT MODEL SOLUTIONS...ESP OP GFS AND LARGELY IGNORED IN FVR OF ECMWF WHICH RETAINED THE GREATEST PREV RUN CONTINUITY. MAIN STORY WILL BE THE DVLPMNT OF YET ANOTHER DEEP COLD CORE CUTOFF LOW ACRS THE GREAT LAKES BY WEEKS END W/LIKELY DAILY DIURNALLY DRIVEN CONVN FRI-MON BFR SYS OPENS AND FILLS. WILL STAY CLOSE TO PRIOR THINKING W/FEW TWEAKS TO POPS ACCOUNTING FOR PREFERRED DIURNAL CYCLE. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...CHAMBERLAIN LONG TERM...HOLSTEN AVIATION...FISHER UPDATE...STEINWEDEL/FISHER in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 728 AM EDT WED JUN 25 2008 .UPDATE/AVIATION... ZONE/GRID UPDATE FORTHCOMING TO INCREASE POPS NORTHWEST HALF TO 2/3RD TO CATEGORICAL FOR THIS MORNING FOR APPROACHING MCS. IR CLOUD TOPS AND WATER VAPOR LOOP INDICATE THE COMPLEX IS LIKELY UNDERGOING A SLOW DECAYING PROCESS. HOWEVER...COMBINATION OF 30 TO 40 KT LLJ STILL FEEDING IN...OBVIOUS MCV SHOWING UP ON RADAR AND SATELLITE DATA...ALL SUGGEST THAT COMPLEX SHOULD BRING SOME RAINFALL TO AT LEAST THE NOTED AREAS FOR PART OF THIS MORNING. WILL KEEP SE AREAS IN THE SCT WORDING FOR NOW WITH BULK OF ACTIVITY REMAINING NORTH AT THIS TIME. WILL CONTINUE TO MONITOR TRENDS ON COMPLEX AND UPDATE MORE IF NEEDED. THERE ARE SOME CLUSTERS OF STORMS EMBEDDED YET WHICH WILL PRODUCE LOCALLY HEAVY RAINFALL ON THE ORDER OF AN INCH OR MORE PER HOUR. AVIATION WISE...UPSTREAM OBS SHOW GENERALLY VFR CONDITIONS IN TERMS OF CIGS/VSBYS IN MOST OF THE AREA OF PRECIP. AREAS THAT EXPERIENCE STORMS ARE SEEING BRIEF DROPS TO MVFR CIGS. FOR NOW AT KSBN HAVE WENT PREDOMINANT VFR WITH A TEMPO BETWEEN 13 AND 15Z BKN025 TO COVER ANY CONVECTION. AT KFWA HAVE KEPT VCSH FOR NOW AND SEE HOW THE AREA PROGRESSES OVER THE NEXT HOUR OR 2. BEYOND 16Z NO CHANGES AS REMAINDER OF MESOSCALE SETUP REMAINS TOO QUESTIONABLE AT THIS POINT. && .PREV DISCUSSION... /ISSUED 416 AM EDT WED JUN 25 2008/ SHORT TERM... TODAY THROUGH THURSDAY NIGHT VERY COMPLICATED FORECAST IN STORE FOR THE PERIOD. CONCERNS ON CLOUD COVER/CONVECTIVE INFLUENCES/AND STRENGTH OF MID LEVEL COOLING ARE ABOUND. CONVECTIVE COMPLEX OVER MO/IL IS BEING SUPPORTED BY A MID LEVEL IMPULSE AND ASSOCIATED LLJ. THIS IMPULSE IS SLOWLY PUSHING EAST TOWARD THE FA. LARGE SCALE ASCENT AND INCREASED LL FLOW PER PROFILER DATA...UNDER STEEPENING MID LEVEL LAPSE RATES IS SUPPORTING SCT SHRA/TS DEVELOPMENT OVER NE IL. EXPECTING THIS AREA OF SHOWERS AND THUNDERSTORMS TO CONTINUE INTO THE FA THROUGH MORNING. TODAY...HAVE UTILIZED THE NGM FOR SYNOPTIC STRUCTURE AS THE GFS/NAM/RUC ALL SUFFER GREATLY FROM CONVECTIVE FEEDBACK AND OTHER BIAS ISSUES. EXPECTING THE MID LEVEL IMPULSE DEPICTED ON WATER VAPOR OVER SOUTHERN IA TO SLOWLY PUSH EAST INTO THE FA. ROBUST CONVECTION/LATENT HEAT RELEASE UPSTREAM WILL FURTHER ENHANCE LL PV FIELDS AND HELP IN THE MAINTENANCE AND PROPAGATION OF THIS IMPULSE OVER THE REGION TODAY. GROWING INSTABILITY PER MID LEVEL COOLING AND ADDED LL MOISTURE WILL SUPPORT CONVECTION THROUGH MOST OF THE DAY...TRANSITIONING EAST THROUGH THE DAY. CLOUD COVER IS EXPECTED TO HIGHLY LIMIT SOLAR INSOLATION OVER NW THIRD OF THE FA...THUS LIMITING INSTABILITY. BEST CHANCE FOR STRONG/SEVERE STORMS WILL BE EAST IF ENOUGH SUN IS REALIZED...WHICH WOULD SUPPORT NEARLY 2000 J/KG CAPE AND PULSE WIND/HAIL THREAT. HOWEVER...CONVECTIVE OUTFLOW AND CLOUD COVER MAY HIGHLY LIMIT TEMPS AND FEEL SEVERE WORDING IS NOT PRUDENT ATTM. TEMPS IN THE GRIDS ARE LIKELY STILL TOO WARM. HAVE LOWERED SOME ALREADY...AND THINGS MAY NEED TO BE LOWERED MORE. IT IS ENTIRELY POSSIBLE THAT A MAJORITY OF THE FA MAY NOT SURPASS THE LOW TO MID 70S. LEAD SW WILL EXIT THE REGION TONIGHT. CONVECTIVE OUTFLOW MODIFIED FRONTAL BOUNDARY OVER IA/MN IS EXPECTED TO BE THE INITIATION POINT OF NEW VIGOROUS CONVECTION THIS AFTERNOON/EVENING. HAVE RETAINED POP MENTION FOR A POSSIBLE MCS PROPAGATING INTO THE FA TONIGHT. THETA-E RIDGING PER 305 K MIXING RATIO PROGS WOULD SUPPORT PROPAGATION OF THIS SYSTEM INTO THE REGION...WITH THE BEST CHANCE FOR TS RESIDING IN NW. THUR...FLATTENING ACTIVE NW FLOW WILL SEND ANOTHER MID LEVEL DISTURBANCE INTO THE REGION ALONG A STALLED FRONTAL BOUNDARY TO THE NORTH. THIS FITS THE MCS/DERECHO PATTERN WELL FOR THE AREA...ESPECIALLY WITH LL MOISTURE AND HEAT IN PLACE. HAVE RETAINED 50 POP MENTION IN THE NORTH...TRENDING TO 30 SOUTH WHERE MID LEVEL WARMING/CAPPING MAY LIMIT CONVECTIVE POTENTIAL. OTHERWISE...HAVE RAISED HIGHS A FEW DEGREES GIVEN SOUTHERLY/DEEP MIXED FLOW. H85 TEMPS AROUND 17C WOULD SPELL MID 80S EASILY FOR MOST OF THE FA. LONG TERM... BRIEF RESPITE TO PNA PATTN ACRS NOAM WILL BREAK TWD SIG AMPLIFICATION ONCE AGAIN BY NXT WEEKEND IN RESPONSE TO SERIES OF FAST MOVING EMBEDDED SW/S WITHIN SEASONABLY STRONG WESTERLY FLW AND DEEP GULF OF AK STORM MOVING INTO WRN CANADA. DIFFICULT TO TIME SW TROUGHS AS SEEN W/INCONSISTENT MODEL SOLUTIONS...ESP OP GFS AND LARGELY IGNORED IN FVR OF ECMWF WHICH RETAINED THE GREATEST PREV RUN CONTINUITY. MAIN STORY WILL BE THE DVLPMNT OF YET ANOTHER DEEP COLD CORE CUTOFF LOW ACRS THE GREAT LAKES BY WEEKS END W/LIKELY DAILY DIURNALLY DRIVEN CONVN FRI-MON BFR SYS OPENS AND FILLS. WILL STAY CLOSE TO PRIOR THINKING W/FEW TWEAKS TO POPS ACCOUNTING FOR PREFERRED DIURNAL CYCLE. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ AVIATION...FISHER UPDATE...STEINWEDEL SHORT TERM...CHAMBERLAIN LONG TERM...HOLSTEN in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 416 AM EDT WED JUN 25 2008 .SHORT TERM... TODAY THROUGH THURSDAY NIGHT VERY COMPLICATED FORECAST IN STORE FOR THE PERIOD. CONCERNS ON CLOUD COVER/CONVECTIVE INFLUENCES/AND STRENGTH OF MID LEVEL COOLING ARE ABOUND. CONVECTIVE COMPLEX OVER MO/IL IS BEING SUPPORTED BY A MID LEVEL IMPULSE AND ASSOCIATED LLJ. THIS IMPULSE IS SLOWLY PUSHING EAST TOWARD THE FA. LARGE SCALE ASCENT AND INCREASED LL FLOW PER PROFILER DATA...UNDER STEEPENING MID LEVEL LAPSE RATES IS SUPPORTING SCT SHRA/TS DEVELOPMENT OVER NE IL. EXPECTING THIS AREA OF SHOWERS AND THUNDERSTORMS TO CONTINUE INTO THE FA THROUGH MORNING. TODAY...HAVE UTILIZED THE NGM FOR SYNOPTIC STRUCTURE AS THE GFS/NAM/RUC ALL SUFFER GREATLY FROM CONVECTIVE FEEDBACK AND OTHER BIAS ISSUES. EXPECTING THE MID LEVEL IMPULSE DEPICTED ON WATER VAPOR OVER SOUTHERN IA TO SLOWLY PUSH EAST INTO THE FA. ROBUST CONVECTION/LATENT HEAT RELEASE UPSTREAM WILL FURTHER ENHANCE LL PV FIELDS AND HELP IN THE MAINTENANCE AND PROPAGATION OF THIS IMPULSE OVER THE REGION TODAY. GROWING INSTABILITY PER MID LEVEL COOLING AND ADDED LL MOISTURE WILL SUPPORT CONVECTION THROUGH MOST OF THE DAY...TRANSITIONING EAST THROUGH THE DAY. CLOUD COVER IS EXPECTED TO HIGHLY LIMIT SOLAR INSOLATION OVER NW THIRD OF THE FA...THUS LIMITING INSTABILITY. BEST CHANCE FOR STRONG/SEVERE STORMS WILL BE EAST IF ENOUGH SUN IS REALIZED...WHICH WOULD SUPPORT NEARLY 2000 J/KG CAPE AND PULSE WIND/HAIL THREAT. HOWEVER...CONVECTIVE OUTFLOW AND CLOUD COVER MAY HIGHLY LIMIT TEMPS AND FEEL SEVERE WORDING IS NOT PRUDENT ATTM. TEMPS IN THE GRIDS ARE LIKELY STILL TOO WARM. HAVE LOWERED SOME ALREADY...AND THINGS MAY NEED TO BE LOWERED MORE. IT IS ENTIRELY POSSIBLE THAT A MAJORITY OF THE FA MAY NOT SURPASS THE LOW TO MID 70S. LEAD SW WILL EXIT THE REGION TONIGHT. CONVECTIVE OUTFLOW MODIFIED FRONTAL BOUNDARY OVER IA/MN IS EXPECTED TO BE THE INITIATION POINT OF NEW VIGOROUS CONVECTION THIS AFTERNOON/EVENING. HAVE RETAINED POP MENTION FOR A POSSIBLE MCS PROPAGATING INTO THE FA TONIGHT. THETA-E RIDGING PER 305 K MIXING RATIO PROGS WOULD SUPPORT PROPAGATION OF THIS SYSTEM INTO THE REGION...WITH THE BEST CHANCE FOR TS RESIDING IN NW. THUR...FLATTENING ACTIVE NW FLOW WILL SEND ANOTHER MID LEVEL DISTURBANCE INTO THE REGION ALONG A STALLED FRONTAL BOUNDARY TO THE NORTH. THIS FITS THE MCS/DERECHO PATTERN WELL FOR THE AREA...ESPECIALLY WITH LL MOISTURE AND HEAT IN PLACE. HAVE RETAINED 50 POP MENTION IN THE NORTH...TRENDING TO 30 SOUTH WHERE MID LEVEL WARMING/CAPPING MAY LIMIT CONVECTIVE POTENTIAL. OTHERWISE...HAVE RAISED HIGHS A FEW DEGREES GIVEN SOUTHERLY/DEEP MIXED FLOW. H85 TEMPS AROUND 17C WOULD SPELL MID 80S EASILY FOR MOST OF THE FA. && .LONG TERM... BRIEF RESPITE TO PNA PATTN ACRS NOAM WILL BREAK TWD SIG AMPLIFICATION ONCE AGAIN BY NXT WEEKEND IN RESPONSE TO SERIES OF FAST MOVING EMBEDDED SW/S WITHIN SEASONABLY STRONG WESTERLY FLW AND DEEP GULF OF AK STORM MOVING INTO WRN CANADA. DIFFICULT TO TIME SW TROUGHS AS SEEN W/INCONSISTENT MODEL SOLUTIONS...ESP OP GFS AND LARGELY IGNORED IN FVR OF ECMWF WHICH RETAINED THE GREATEST PREV RUN CONTINUITY. MAIN STORY WILL BE THE DVLPMNT OF YET ANOTHER DEEP COLD CORE CUTOFF LOW ACRS THE GREAT LAKES BY WEEKS END W/LIKELY DAILY DIURNALLY DRIVEN CONVN FRI-MON BFR SYS OPENS AND FILLS. WILL STAY CLOSE TO PRIOR THINKING W/FEW TWEAKS TO POPS ACCOUNTING FOR PREFERRED DIURNAL CYCLE. && .AVIATION.../06Z TAFS/ AVIATION FORECAST CONCERNS INCLUDE SHRA/TS CHANCES AT SBN AND FWA. CURRENT TS COMPLEX IN MO/IL IS PUSHING NE AND IS EXPECTED TO ENTER THE FA BY 09-10Z SUPPORTED BY WAA. HAVE INCLUDED TEMPO AT SBN WHERE BEST LIFT AND INSTABILITY WILL BE FOUND. ONLY INCLUDED CB/VCSH MENTION AT FWA...DUE TO CONCERNS ON CONVECTIVE COVERAGE. AFTERNOON PERIOD WILL BE A DIFFICULT FORECAST DUE TO CONCERNS ON CONVECTIVE INITIATION. QUESTIONS ON CONVECTIVE DEBRIS/STRENGTH OF MID LEVEL WAVE/AND BEST INSTABILITY WILL MAKE PIN POINTING TSRA DIFFICULT. FELT BEST AVENUE AT THIS TIME IS TO RETAIN CB AND VCTS MENTION UNTIL BETTER TRENDS ARE ESTABLISHED. A SECOND ROUND OF CONVECTION IS POSSIBLE WED EVENING INTO THE NIGHT PERIOD AS A TS COMPLEX WILL DEVELOP OVER IA/MN AND PUSH SE. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...CHAMBERLAIN LONG TERM...HOLSTEN AVIATION...CHAMBERLAIN in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 956 PM CDT THU JUN 26 2008 .UDPATE... EXPANDING FLASH FLOOD WATCH FROM EARLIER UPDATE. SEE DISCUSSION BELOW. && .DISCUSSION... MAIN CONCERN TONIGHT IS OBVIOUSLY APPROACHING NE MCS. EXTRAPOLATION BRINGS THE LEADING EDGE TO MY SWRN ZONES AROUND 200 AM SO HAVE BOOSTED POPS SRN SECTIONS TO CATEGORICAL WORDING...NOW AREA WIDE. MEAN WIND AND CORFIDI VECTORS SUGGEST COMPLEX SHOULD NOT MOVE NORTH OF DUE EAST AND WILL LIKELY PUSH SOUTHEASTWARD WITH TIME. RUC 310K ISENT SFC FOCUSES MOISTURE CONVERGENCE INTO SWRN IA AS WELL ON NOSE OF 35-50KT LLJ WHICH WOULD ALSO KEEP COMPLEX MORE SOUTH THAN NORTH. WITH SRN IA NOW SEEMING TO BE UNDER THE GUN...WILL EXPAND FFA TO ALL AREAS ALONG AND SOUTH OF HIGHWAY 3...INCLUDING SWRN IA. NOT SURE ON HOW STRONG THE MCS WILL BE BY THE TIME IT GETS HERE. THERE IS SOME CONCERN THAT NRN KS MCS MAY STEAL SOME OF THE INFLOW POTENTIAL...AND RUC CINS COMPUTED FROM VARIOUS ELEVATED LEVELS SUGGEST VALUES ARE HIGH ENOUGH TO SUPRESS STRENGTH SOMEWHAT. HOWEVER HIGHER MCS MAINTENANCE PROBS ADVANCE INTO IA OVERNIGHT WITH SHEAR AND MUCAPES...AND KINEMATIC FORCING FROM SHORT WAVE MAY BE ABLE TO OVERCOME ANY APPARENT INHIBITION. THUS SEE NO REASON WHY SVR AND HEAVY RAIN THREATS WILL NOT CONTINUE OVERNIGHT INTO IA. STRONG MOISTURE TRANSPORT...HIGH WCDS AND INCREASING PWS STILL SUPPORT HEAVY RAINS AND FLASH FLOOD WATCH. MEAN WIND IS ONLY 20-25 OVER IA BY 09Z AND CORFIDI VECTORS/MBE MOVEMENT EVEN LESS TO THE SOUTH. && .PREV DISCUSSION... (TONIGHT) ONCE AGAIN THE FORECAST FOR TONIGHT IS QUITE COMPLEX...MADE MORE DIFFICULT BY THE COUPLE ROUNDS OF CONVECTION AND THE RATHER STRONG COLD POOL ALOFT. TEMPERATURES THIS AFTERNOON...EVEN OUTSIDE OF THE CONVECTION...HAS HOVERED IN THE MID TO UPPER 60S WEST WITH LOWER TO MID 70S WEST. CAPE VALUES ARE STILL RESPECTABLE OVER SOUTHERN IOWA BUT NOT NEAR AS LARGE AS THEY WERE AND SHEAR REMAINS WEAK. GIVEN THAT CAPES ARE STILL AROUND 2000 J/KG AND LOW LEVEL MOISTURE IS STILL DECENT WITH A COLD POOL ALOFT...THERE WILL LIKELY BE SPOTTY SHOWERS AND ISOLATED THUNDERSTORMS THROUGH THE REST OF THE AFTERNOON AND EARLY EVENING. THE KICKER WILL BE A SHORTWAVE PUSHING ACROSS THE NORTHERN PLAINS WHICH SHOULD INITIATE THUNDERSTORMS OVER THE DAKOTAS AND NEBRASKA WHICH SHOULD THEN DEVELOP DOWN THE INSTABILITY AXIS OVER THE EASTERN DAKOTAS INTO WESTERN IOWA. THUNDERSTORMS WITH HEAVY RAINFALL WILL AGAIN BE LIKELY OVERNIGHT THROUGH FRIDAY MORNING. THE MODELS HAVE BEEN NO HELP AS THEY DO NOT REALLY PICK UP ON THE STRENGTH OF THE COLD POOL ALOFT AND THEY ARE ALL OVER THE PLACE WITH THE PRECIP AND QPF. FOR NOW THE BEST INTERPRETATION OF THE DATA SUGGESTS AN MCS OVER THE DAKOTAS...OR SEVERAL CLUSTERS OF STORMS TO THE WEST...WILL EVENTUALLY COME TOGETHER AND ROLL ACROSS CENTRAL IOWA LATE EVENING OR OVERNIGHT ONCE MORE AND PERSIST THROUGH THE BETTER PART OF FRIDAY. (FRI-THU) ACTIVE PERIOD WILL CONTINUE THROUGH FRIDAY BEFORE LARGE UPPER LEVEL SYSTEM CURRENTLY OVER ALBERTA DIVES SOUTHEAST INTO THE WESTERN GREAT LAKES ON SATURDAY...BUCKLING THE ZONAL FLOW TO A MORE NORTHWEST FLOW THROUGH THE REMAINDER OF THE FORECAST PERIOD. CERTAINLY UNCERTAINTIES PERSIST FOR FRIDAY AND WILL BE HIGHLY SUBJECTIVE TO WHAT OCCURS TONIGHT AND INTO FRIDAY MORNING. COLD FRONTAL BOUNDARY SHOULD REACH NORTHWEST IOWA BY 12Z AND PROGRESS SLOWLY THROUGH THE AREA AND BE OVER THE SOUTHEAST FORECAST AREA BY 21Z. REMNANTS OF AN MCS MOVING OUT OF SOUTH DAKOTA AND NORTHWEST IOWA TONIGHT SHOULD BE OVER PORTIONS OF THE AREA FRIDAY MORNING. MUCH LIKE TODAY...RECOVERY DURING THE DAY WILL BE DEPENDANT IF THE CLOUD COVER CAN BREAK BY LATE MORNING TO THE EARLY AFTERNOON. TEMPERATURES IN THE LOWER TO MID 80S BY THE AFTERNOON OVER THE SOUTHEAST WILL PUSH MIXED LAYER CAPES TO OVER 3000 J/KG. THE COLD FRONT MOVING INTO THIS INSTABILITY WOULD BE ENOUGH TO FIRE A MULTICELLULAR SQUALL LINE ALONG THE BOUNDARY THAT SHOULD THEN BE FAIRLY PROGRESSIVE MOVING EAST INTO THE EARLY EVENING HOURS. THE UPPER LEVEL CLOSED LOW PRESSURE SYSTEM WILL MOVE SOUTHEAST THROUGH MINNESOTA ON SATURDAY. WITH THE UPPER LEVEL ENERGY AND THE MID LEVEL COLD CORE PASSING NEARBY...SHOULD NOT HAVE MUCH PROBLEM INITIATING THUNDERSTORMS BY SATURDAY AFTERNOON OVER THE NORTHEAST HALF. GIVEN THE STEEP MID LEVEL LAPSE RATES...LOW MELTING LEVELS AND NEAR UNIDIRECTIONAL FLOW...LARGE HAIL MAINLY NICKEL SIZED OR LESS AND WIND GUSTS TO 60 MPH. WITH THE COOLER LOW TO MID LEVEL TEMPERATURES AROUND...HIGH TEMPERATURES WILL HAVE A DIFFICULT TIME RISING OUT OF THE 70S. COOL TEMPERATURES WILL PERSIST ON SUNDAY WITH A FEW SHOWERS AND THUNDERSTORMS POSSIBLE OVER THE NORTHEAST DURING THE AFTERNOON. GRADUAL WARMING NEXT WEEK. NEXT BEST CHANCE FOR THUNDERSTORMS WILL ARRIVE WEDNESDAY INTO THURSDAY. && .AVIATION...27/00Z PRECIPITATION HAS EXITED IA FOR THE MOST PART WITH ACTIVE CONVECTION REMAINING OVER KS AND MO THIS EVENING. HOWEVER ATTENTION TURNS UPSTREAM TO LARGE THUNDERSTORM COMPLEX DEVELOPING OVER WESTERN NE. EXACT TIMING UNCERTAIN THIS FAR OUT...BUT FULLY EXPECT THIS COMPLEX TO AFFECT AT LEAST PARTS OF IA...LIKELY DSM/OTM DURING THE EARLY MORNING HOURS. HAVE VICINITY WORDING NOW AND WILL HIT HARDER WITH 06Z PACKAGE AS DETAILS BECOME CLEARER. FRONTAL PASSAGE FRI AFTERNOON MAY DEVELOP ADDITIONAL STORMS OVER ALL BUT OTM AREA BUT CONFIDENCE IN TIMING AND DETAILS NOT GREAT ENOUGH TO INCLUDE MENTION AT THE MOMENT...ESPECIALLY WITH OVERNIGHT STORMS POSSIBLY AFFECTING THINGS. && .DMX WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH HIGHWAY 3 SOUTH TO MISSOURI BORDER TIL 12Z. && $$ FAB/RAD/BSS ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 1249 AM CDT THU JUN 26 2008 .UPDATE... INCLUSION OF 06Z TAFS AND CANCELLATION OF SVR TSTM WATCH 606. && .PREV DISCUSSION... THE FORECAST TONIGHT IS QUITE COMPLEX AS THERE ARE SEVERAL FEATURES OVER/NEAR THE CWA. CURRENTLY WE ARE QUITE UNSTABLE WITH 4000 J/KG OF CAPE OVER THE SW THIRD OF IA BUT SHEAR IS QUITE WEAK...GENERALLY 20-25KTS OR LESS. OVER THE NORTHWEST...A FRONTAL BOUNDARY EXISTS FROM A LOW IN NE MN. THE FRONT EXTENDS INTO FAR NW IA THEN ALONG THE NEB/SDKTA BORDER. THERE IS WEAK CONVERGENCE ALONG THE SURFACE FRONT BUT SO FAR IT HAS NOT BEEN ABLE TO PRODUCE/SUSTAIN THUNDERSTORMS. ALOFT...THE FLOW IS WEAK AND THERE IS NOT A LOT OF SUPPORT. HOWEVER...RUC ANALYSIS DOES INDICATE A COUPLE OF WEAK VORT CENTERS...ONE OVER NW IA...PROBABLY AIDING IN THE SHOWERS UP THERE...AND ONE IN NORTHEAST KS MOVING INTO SW IA. CAPE VALUES IN THIS AREA ARE EVEN HIGHER THAN IN SW IA AND THERE ARE NO THUNDERSTORMS DEVELOPING YET. HAVING SAID ALL THIS...ANY ONE OF THESE FEATURES CAN TRIGGER STORMS TONIGHT AT ANY TIME. THE LACK OF DEVELOPMENT THUS FAR IS THE PERPLEXING PART. MID/UPPER LEVEL WIND FIELDS ARE BETTER OVER MN CLOSER TO THE LOW. I WOULD EXPECT DEVELOPMENT TO INITIATE THERE THEN TRAVEL DOWN THE FRONTAL BOUNDARY THIS EVENING. I BELIEVE THE NAM HAS A GOOD HANDLE ON THE SCENARIO DEVELOPING THE PRECIP FURTHER SOUTH...WHERE THE THE FRONT WILL EVENTUALLY SAG INTO THE HIGH CAPE AREA. LATER TONIGHT A LLJ DEVELOPS AND THIS WILL PROBABLY AID IN THE DEVELOPMENT OF AN MCS MOVING SLOWLY ACROSS THE STATE OVERNIGHT INTO THURSDAY. WITH THE HIGH LEVEL OF UNCERTAINTY OVER JUST WHERE INITIATION WILL BEGIN I HAVE PLACED CHANCE POPS OVER THE CWA FOR TONIGHT. THE HIGHEST POPS STILL REMAIN NORTH BUT WITH FAIRLY DEEP MOISTURE OVER THE SOUTH...ANY STORMS THAT DEVELOP DOWN THERE WILL ALSO PRODUCE VERY HEAVY RAINFALL. MOST ACTIVE PERIOD REMAINS WITHIN THE FIRST 60 HOURS OF THE FORECAST PERIOD. A FEW THUNDERSTORMS POSSIBLY ONGOING AT THE START OF THE PERIOD AT 12Z THURSDAY. THE BIGGER SHOW IS STILL EXPECTED TO BE A DEVELOPING MCS OVER WYOMING LATE THIS EVENING THEN ROLL THROUGH SOUTH DAKOTA OVERNIGHT BEFORE REACHING NORTHERN IOWA DURING THE DAY ON THURSDAY. SOME SFC HEATING IS LIKELY AHEAD OF THE SYSTEM AND THIS SHOULD ALLOW FOR AN INCREASINGLY UNSTABLE AIR MASS TO DEVELOP FOR THE STORMS TO FEED ON. SEVERE STORMS ALONG WITH AREAS OF HEAVY RAINFALL WILL BE POSSIBLE. ADDITIONAL STORMS EXPECTED THURSDAY NIGHT BEFORE THE PRIMARY FRONTAL BOUNDARY ARRIVES ON FRIDAY. GOOD INSTABILITY LIKELY AGAIN ON FRIDAY WITH MIX LAYER CAPES OF 2000 TO 2500 J/KG HOWEVER THE MAIN UPPER LEVEL FORCING WILL PASS TO THE NORTH. STILL ENOUGH SHEAR WILL REMAIN FOR SOME SEVERE MULTICELL STORMS AND ISOLATED SUPER CELLS. THE WEEKEND WILL BE DOMINATED BY A LARGE UPPER LEVEL LOW MOVING SLOWING THROUGH THE WESTERN GREAT LAKES REGION BRINGING CYCLONIC FLOW TO IOWA. HAVE COOLED HIGH TEMPERATURES AND ADDED LOW POPS TO THE NORTHEAST FOR EACH AFTERNOON AS IMPULSES ROTATE AROUND THE UPPER LOW. COOL TEMPERATURES THROUGH THE COLUMN WILL LEAD TO SOME INSTABILITY DURING THE AFTERNOONS. GRADUALLY WARMER NEXT WEEK WITH THE NEXT BEST CHANCE OF PRECIPITATION ARRIVING TUESDAY NIGHT AND INTO WEDNESDAY. && .AVIATION...26/06Z THUNDERSTORMS JUST ABOVE TO EXIT SRN IA INCLUDING AROUND KOTM. WITH LIGHT WINDS AND LINGERING LOW LEVEL MOISTURE FROM HUMID WED AND RECENT RAINS...EXPECT PATCHY FOG TO DEVELOP. HOWEVER EXTENSIVE MIDDLE CLOUD COVER FROM DEPARTING STORMS AND THUNDERSTORM COMPLEX OVER DAKOTAS SHOULD DEEP RADIATIVE COOLING FROM BEING TOO EXTREME SO ONLY MVFR FOG MENTION FOR NOW. CONFIDENCE IN DAKOTAS COMPLEX MAKING IT HERE RATHER LOW FOR THE TIME BEING...SO HAVE IGNORED AT 06Z. HOWEVER FULLY EXPECT ANOTHER ROUND OF THUNDERSTORMS SOMETIME TODAY OR THU EVENING. REALLY DO NOT HAVE A FEEL FOR LOCATION OR TIMING YET SO JUST MENTIONED CB RATHER THAN 6+ HOURS OF THUNDERSTORMS IN TERMINALS. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ RAD/FAB/BSS ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 336 PM CDT WED JUN 25 2008 .SHORT TERM /TONIGHT/... THE FORECAST TONIGHT IS QUITE COMPLEX AS THERE ARE SEVERAL FEATURES OVER/NEAR THE CWA. CURRENTLY WE ARE QUITE UNSTABLE WITH 4000 J/KG OF CAPE OVER THE SW THIRD OF IA BUT SHEAR IS QUITE WEAK...GENERALLY 20-25KTS OR LESS. OVER THE NORTHWEST...A FRONTAL BOUNDARY EXISTS FROM A LOW IN NE MN. THE FRONT EXTENDS INTO FAR NW IA THEN ALONG THE NEB/SDKTA BORDER. THERE IS WEAK CONVERGENCE ALONG THE SURFACE FRONT BUT SO FAR IT HAS NOT BEEN ABLE TO PRODUCE/SUSTAIN THUNDERSTORMS. ALOFT...THE FLOW IS WEAK AND THERE IS NOT A LOT OF SUPPORT. HOWEVER...RUC ANALYSIS DOES INDICATE A COUPLE OF WEAK VORT CENTERS...ONE OVER NW IA...PROBABLY AIDING IN THE SHOWERS UP THERE...AND ONE IN NORTHEAST KS MOVING INTO SW IA. CAPE VALUES IN THIS AREA ARE EVEN HIGHER THAN IN SW IA AND THERE ARE NO THUNDERSTORMS DEVELOPING YET. HAVING SAID ALL THIS...ANY ONE OF THESE FEATURES CAN TRIGGER STORMS TONIGHT AT ANY TIME. THE LACK OF DEVELOPMENT THUS FAR IS THE PERPLEXING PART. MID/UPPER LEVEL WIND FIELDS ARE BETTER OVER MN CLOSER TO THE LOW. I WOULD EXPECT DEVELOPMENT TO INITIATE THERE THEN TRAVEL DOWN THE FRONTAL BOUNDARY THIS EVENING. I BELIEVE THE NAM HAS A GOOD HANDLE ON THE SCENARIO DEVELOPING THE PRECIP FURTHER SOUTH...WHERE THE THE FRONT WILL EVENTUALLY SAG INTO THE HIGH CAPE AREA. LATER TONIGHT A LLJ DEVELOPS AND THIS WILL PROBABLY AID IN THE DEVELOPMENT OF AN MCS MOVING SLOWLY ACROSS THE STATE OVERNIGHT INTO THURSDAY. WITH THE HIGH LEVEL OF UNCERTAINTY OVER JUST WHERE INITIATION WILL BEGIN I HAVE PLACED CHANCE POPS OVER THE CWA FOR TONIGHT. THE HIGHEST POPS STILL REMAIN NORTH BUT WITH FAIRLY DEEP MOISTURE OVER THE SOUTH...ANY STORMS THAT DEVELOP DOWN THERE WILL ALSO PRODUCE VERY HEAVY RAINFALL. .LONG TERM /THU-WED/... MOST ACTIVE PERIOD REMAINS WITHIN THE FIRST 60 HOURS OF THE FORECAST PERIOD. A FEW THUNDERSTORMS POSSIBLY ONGOING AT THE START OF THE PERIOD AT 12Z THURSDAY. THE BIGGER SHOW IS STILL EXPECTED TO BE A DEVELOPING MCS OVER WYOMING LATE THIS EVENING THEN ROLL THROUGH SOUTH DAKOTA OVERNIGHT BEFORE REACHING NORTHERN IOWA DURING THE DAY ON THURSDAY. SOME SFC HEATING IS LIKELY AHEAD OF THE SYSTEM AND THIS SHOULD ALLOW FOR AN INCREASINGLY UNSTABLE AIR MASS TO DEVELOP FOR THE STORMS TO FEED ON. SEVERE STORMS ALONG WITH AREAS OF HEAVY RAINFALL WILL BE POSSIBLE. ADDITIONAL STORMS EXPECTED THURSDAY NIGHT BEFORE THE PRIMARY FRONTAL BOUNDARY ARRIVES ON FRIDAY. GOOD INSTABILITY LIKELY AGAIN ON FRIDAY WITH MIX LAYER CAPES OF 2000 TO 2500 J/KG HOWEVER THE MAIN UPPER LEVEL FORCING WILL PASS TO THE NORTH. STILL ENOUGH SHEAR WILL REMAIN FOR SOME SEVERE MULTICELL STORMS AND ISOLATED SUPER CELLS. THE WEEKEND WILL BE DOMINATED BY A LARGE UPPER LEVEL LOW MOVING SLOWING THROUGH THE WESTERN GREAT LAKES REGION BRINGING CYCLONIC FLOW TO IOWA. HAVE COOLED HIGH TEMPERATURES AND ADDED LOW POPS TO THE NORTHEAST FOR EACH AFTERNOON AS IMPULSES ROTATE AROUND THE UPPER LOW. COOL TEMPERATURES THROUGH THE COLUMN WILL LEAD TO SOME INSTABILITY DURING THE AFTERNOONS. GRADUALLY WARMER NEXT WEEK WITH THE NEXT BEST CHANCE OF PRECIPITATION ARRIVING TUESDAY NIGHT AND INTO WEDNESDAY. && .AVIATION...25/18Z DIFFICULT FORECAST TODAY AS THE MODELS ARE NOT HANDLING THE MOISTURE VERY WELL. LOW PRESSURE OVER MN HAS A COLD FRONT EXTENDING SW TO NR NW IA THEN INTO SERN SDKTA AND NRN NEB. THE MODELS ARE FAIRLY CONSISTENT IN BREAKING OUT PRECIP THIS EVENING AND OVERNIGHT BUT WITH WEAK TO NO UPPER LEVEL SUPPORT...CONVECTION WILL HAVE TO BE BASED LARGELY ON CONVERGENCE ALONG THE FRONT. ONCE THE STORMS START TO DEVELOP THEY SHOULD GO QUICKLY IN THE UNSTABLE ENVIRONMENT WE ARE IN. WE MAY NEED THE HELP OF THE LLJ TO GET THINGS GOING. IN THAT CASE IT WOULD BE LATER THIS EVENING. THERE IS A POSSIBILITY THAT THE STORMS MAY FIRE FURTHER SOUTH ALONG THE FRONT IN WHICH CASE THE SOUTHERN TAF SITES WOULD ALSO BE AT RISK OF STORMS. I HAVE LEANED TOWARDS THIS SOLUTION AS SAT PIX SHOWING CONVECTIVE ELEMENTS OVER SRN/CENT NEB. MVFR COND W/ LCL IFR COND WL PREVAIL IN TSRA. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ LONG TERM...DONAVON SHORT TERM/AVIATION...FAB ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 113 PM CDT THU JUN 26 2008 .UPDATE... && .AVIATION...18Z TAFS [RSL/SLN/HUT/ICT/CNU] VFR CONDITIONS EXPECTED DURING THE VALID PERIOD. LEE TROF WILL LEAD TO SRLY WIND GUSTS (25-30KT) THIS PM IN CNTRL/S-CNTRL KS. WINDS WILL BECOME W-SWRLY TOWARD END OF VALID PERIOD JUST AHEAD OF APPROACHING COLD FRONT. JMC && PREV DISCUSSION... /ISSUED 316 AM CDT THU JUN 26 2008/ DISCUSSION... FORECAST CONCERNS...CONVECTIVE CHANCES/TRENDS AND SEVERE POTENTIAL FRIDAY AFTERNOON THROUGH FRIDAY NIGHT. ONLY SUBTLE CHANGES IN SENSIBLE WEATHER EXPECTED FOR TODAY...SO WILL FOLLOW A MODIFIED PERSISTENCE APPROACH TO THE FORECAST AND MOST GRID ELEMENTS TODAY. A BIT MORE OF A CAP EARLY THIS MORNING BASED ON RUC MODEL...SO HOPEFULLY WILL NOT SEE ANOTHER SUNRISE SURPRISE TOWARD DAWN...ISOLATED AS IT WAS YESTERDAY. OTHERWISE EXPECT A COUPLE LOCALES TO APPROACH/TOUCH THE CENTURY MARK ACROSS CENTRAL KANSAS THIS AFTERNOON. DESPITE MAXS IN THE LOW/MID 90S FOR THE REST OF THE AREA...IT WILL FEEL CLOSE TO 100 WITH COMBO OF HEAT AND HUMIDITY. CONVECTION THAT DEVELOPS NORTHWEST OF THE AREA THIS EVENING MAY CLIP NORTHERN PORTIONS OF THE FORECAST AREA TONIGHT...SO WILL KEEP A SLIGHT CHANCE IN FOR THOSE AREAS. HOWEVER...MAIN FOCUS FOR MORE ORGANIZED CONVECTION WILL COME LATER FRIDAY INTO EARLY SATURDAY MORNING...AS A STRONG SUMMER-TIME UPPER TROF AND THE ASSOCIATED COLD FRONT DROPS SOUTHEAST ACROSS THE MIDWEST. THIS TROF WILL DEEPEN ACROSS THE GREAT LAKES WITH A REINFORCING SHOT OF COOLISH/DRIER AIR SATURDAY NIGHT INTO SUNDAY. THE FRONT ON FRIDAY EVENING LOOKS TO ENCOUNTER A VERY UNSTABLE AIRMASS ACROSS EASTERN KANSAS...AND CONFIDENCE CONTINUES BUILD ON A SEVERE CONVECTIVE EPISODE...SO HAVE UPPED POPS INTO THE LIKELY CATEGORY FOR AREAS EAST OF THE KANSAS TURNPIKE FRIDAY NIGHT. STILL SOME QUESTION AS TO THE TIMING/SOUTHWARD MOVE OF THE FRONT...WITH THE NAM MORE PROGRESSIVE THAN OTHER MODELS. THIS MAY HAVE MORE OF AN IMPACT ON MAXS FOR CENTRAL KANSAS ON FRIDAY...AND FOR NOW WILL STILL KEEP THINGS QUITE TOASTY...HOWEVER AREAS OF SOUTH CENTRAL LOOK TO BE THE HOTTEST...ESPECIALLY FOR AREAS WEST AND SOUTHWEST OF GREATER WICHITA WHERE PERHAPS A DRIER SOUTHWEST FLOW AND SOME COMPRESSIONAL WARMING EFFECTS WILL ENHANCE MAX POTENTIAL LATE IN THE AFTERNOON. OTHERWISE...HAVE TEMPERED MAXS FOR THE WEEKEND...ESPECIALLY FOR SUNDAY...WITH MODEL CONSENSUS SUGGESTING RELATIVELY COOLER AIR WILL HOLD SWAY THRU THE WEEKEND NOW. DARMOFAL AVIATION... 06Z TAFS...ICT/SLN/HUT/CNU/RSL...VFR CONDITIONS ANTICIPATED OVER THE NEXT 24 HOURS. STRENGTHENING AND VEERING LOW-LEVEL JET TONIGHT MAY INITIATE A STRAY THUNDERSTORM SOMEWHERE ACROSS CENTRAL AND SOUTHEAST KANSAS TONIGHT...BUT PREDICTABILITY IS TOO LOW AND COVERAGE TOO SPARSE TO MENTION VCTS IN THE TAFS. OTHERWISE...STOUT SOUTHERLY WINDS WILL COMMENCE BY MID-MORNING THURSDAY...AS LOW PRESSURE STRENGTHENS ACROSS THE WESTERN HIGH PLAINS...AND A COLD FRONT GETS ITS ACT TOGETHER NORTHWEST OF THE AREA. KLEINSASSER && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 95 73 97 71 / 10 10 20 50 HUTCHINSON 96 72 98 69 / 10 10 30 50 NEWTON 95 73 97 70 / 10 10 30 50 ELDORADO 94 73 95 71 / 10 10 20 60 WINFIELD-KWLD 94 73 96 72 / 10 10 20 60 RUSSELL 100 71 95 66 / 10 20 40 20 GREAT BEND 99 71 97 67 / 10 10 40 30 SALINA 99 73 97 68 / 10 20 40 40 MCPHERSON 97 73 97 69 / 10 10 40 40 COFFEYVILLE 92 72 93 72 / 10 10 20 60 CHANUTE 92 72 93 72 / 10 20 20 60 IOLA 92 72 93 72 / 10 20 20 60 PARSONS-KPPF 92 72 93 72 / 10 10 20 60 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 632 AM CDT THU JUN 26 2008 .AVIATION... FOR 12Z TAFS...VERY LITTLE IN THE WAY OF AVIATION CONCERNS TODAY WITH VFR CONDITIONS EXPECTED ALL DAY. SURFACE LOW PRESSURE WILL STRENGTHEN OVER THE HIGH PLAINS TODAY ALLOWING SOUTH WINDS TO BE A BIT STRONGER THAN THE LAST FEW DAYS. MOST SITES(WITH THE EXCEPTION OF KCNU) CAN EXPECT SOUTH WINDS AT 20 MPH WITH GUSTS TO 30 MPH. THE BULK OF THE STORMS TODAY AND TONIGHT WILL REMAIN NORTH OF KANSAS ALONG A COLD FRONT. LAWSON && .PREV DISCUSSION... /ISSUED 316 AM CDT THU JUN 26 2008/ DISCUSSION... FORECAST CONCERNS...CONVECTIVE CHANCES/TRENDS AND SEVERE POTENTIAL FRIDAY AFTERNOON THROUGH FRIDAY NIGHT. ONLY SUBTLE CHANGES IN SENSIBLE WEATHER EXPECTED FOR TODAY...SO WILL FOLLOW A MODIFIED PERSISTENCE APPROACH TO THE FORECAST AND MOST GRID ELEMENTS TODAY. A BIT MORE OF A CAP EARLY THIS MORNING BASED ON RUC MODEL...SO HOPEFULLY WILL NOT SEE ANOTHER SUNRISE SURPRISE TOWARD DAWN...ISOLATED AS IT WAS YESTERDAY. OTHERWISE EXPECT A COUPLE LOCALES TO APPROACH/TOUCH THE CENTURY MARK ACROSS CENTRAL KANSAS THIS AFTERNOON. DESPITE MAXS IN THE LOW/MID 90S FOR THE REST OF THE AREA...IT WILL FEEL CLOSE TO 100 WITH COMBO OF HEAT AND HUMIDITY. CONVECTION THAT DEVELOPS NORTHWEST OF THE AREA THIS EVENING MAY CLIP NORTHERN PORTIONS OF THE FORECAST AREA TONIGHT...SO WILL KEEP A SLIGHT CHANCE IN FOR THOSE AREAS. HOWEVER...MAIN FOCUS FOR MORE ORGANIZED CONVECTION WILL COME LATER FRIDAY INTO EARLY SATURDAY MORNING...AS A STRONG SUMMER-TIME UPPER TROF AND THE ASSOCIATED COLD FRONT DROPS SOUTHEAST ACROSS THE MIDWEST. THIS TROF WILL DEEPEN ACROSS THE GREAT LAKES WITH A REINFORCING SHOT OF COOLISH/DRIER AIR SATURDAY NIGHT INTO SUNDAY. THE FRONT ON FRIDAY EVENING LOOKS TO ENCOUNTER A VERY UNSTABLE AIRMASS ACROSS EASTERN KANSAS...AND CONFIDENCE CONTINUES BUILD ON A SEVERE CONVECTIVE EPISODE...SO HAVE UPPED POPS INTO THE LIKELY CATEGORY FOR AREAS EAST OF THE KANSAS TURNPIKE FRIDAY NIGHT. STILL SOME QUESTION AS TO THE TIMING/SOUTHWARD MOVE OF THE FRONT...WITH THE NAM MORE PROGRESSIVE THAN OTHER MODELS. THIS MAY HAVE MORE OF AN IMPACT ON MAXS FOR CENTRAL KANSAS ON FRIDAY...AND FOR NOW WILL STILL KEEP THINGS QUITE TOASTY...HOWEVER AREAS OF SOUTH CENTRAL LOOK TO BE THE HOTTEST...ESPECIALLY FOR AREAS WEST AND SOUTHWEST OF GREATER WICHITA WHERE PERHAPS A DRIER SOUTHWEST FLOW AND SOME COMPRESSIONAL WARMING EFFECTS WILL ENHANCE MAX POTENTIAL LATE IN THE AFTERNOON. OTHERWISE...HAVE TEMPERED MAXS FOR THE WEEKEND...ESPECIALLY FOR SUNDAY...WITH MODEL CONSENSUS SUGGESTING RELATIVELY COOLER AIR WILL HOLD SWAY THRU THE WEEKEND NOW. DARMOFAL AVIATION... 06Z TAFS...ICT/SLN/HUT/CNU/RSL...VFR CONDITIONS ANTICIPATED OVER THE NEXT 24 HOURS. STRENGTHENING AND VEERING LOW-LEVEL JET TONIGHT MAY INITIATE A STRAY THUNDERSTORM SOMEWHERE ACROSS CENTRAL AND SOUTHEAST KANSAS TONIGHT...BUT PREDICTABILITY IS TOO LOW AND COVERAGE TOO SPARSE TO MENTION VCTS IN THE TAFS. OTHERWISE...STOUT SOUTHERLY WINDS WILL COMMENCE BY MID-MORNING THURSDAY...AS LOW PRESSURE STRENGTHENS ACROSS THE WESTERN HIGH PLAINS...AND A COLD FRONT GETS ITS ACT TOGETHER NORTHWEST OF THE AREA. KLEINSASSER && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 95 73 97 71 / 10 10 20 50 HUTCHINSON 96 72 98 69 / 10 10 30 50 NEWTON 95 73 97 70 / 10 10 30 50 ELDORADO 94 73 95 71 / 10 10 20 60 WINFIELD-KWLD 94 73 96 72 / 10 10 20 60 RUSSELL 100 71 95 66 / 10 20 40 20 GREAT BEND 99 71 97 67 / 10 10 40 30 SALINA 99 73 97 68 / 10 20 40 40 MCPHERSON 97 73 97 69 / 10 10 40 40 COFFEYVILLE 92 72 93 72 / 10 10 20 60 CHANUTE 92 72 93 72 / 10 20 20 60 IOLA 92 72 93 72 / 10 20 20 60 PARSONS-KPPF 92 72 93 72 / 10 10 20 60 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 316 AM CDT THU JUN 26 2008 .DISCUSSION... FORECAST CONCERNS...CONVECTIVE CHANCES/TRENDS AND SEVERE POTENTIAL FRIDAY AFTERNOON THROUGH FRIDAY NIGHT. ONLY SUBTLE CHANGES IN SENSIBLE WEATHER EXPECTED FOR TODAY...SO WILL FOLLOW A MODIFIED PERSISTENCE APPROACH TO THE FORECAST AND MOST GRID ELEMENTS TODAY. A BIT MORE OF A CAP EARLY THIS MORNING BASED ON RUC MODEL...SO HOPEFULLY WILL NOT SEE ANOTHER SUNRISE SURPRISE TOWARD DAWN...ISOLATED AS IT WAS YESTERDAY. OTHERWISE EXPECT A COUPLE LOCALES TO APPROACH/TOUCH THE CENTURY MARK ACROSS CENTRAL KANSAS THIS AFTERNOON. DESPITE MAXS IN THE LOW/MID 90S FOR THE REST OF THE AREA...IT WILL FEEL CLOSE TO 100 WITH COMBO OF HEAT AND HUMIDITY. CONVECTION THAT DEVELOPS NORTHWEST OF THE AREA THIS EVENING MAY CLIP NORTHERN PORTIONS OF THE FORECAST AREA TONIGHT...SO WILL KEEP A SLIGHT CHANCE IN FOR THOSE AREAS. HOWEVER...MAIN FOCUS FOR MORE ORGANIZED CONVECTION WILL COME LATER FRIDAY INTO EARLY SATURDAY MORNING...AS A STRONG SUMMER-TIME UPPER TROF AND THE ASSOCIATED COLD FRONT DROPS SOUTHEAST ACROSS THE MIDWEST. THIS TROF WILL DEEPEN ACROSS THE GREAT LAKES WITH A REINFORCING SHOT OF COOLISH/DRIER AIR SATURDAY NIGHT INTO SUNDAY. THE FRONT ON FRIDAY EVENING LOOKS TO ENCOUNTER A VERY UNSTABLE AIRMASS ACROSS EASTERN KANSAS...AND CONFIDENCE CONTINUES BUILD ON A SEVERE CONVECTIVE EPISODE...SO HAVE UPPED POPS INTO THE LIKELY CATEGORY FOR AREAS EAST OF THE KANSAS TURNPIKE FRIDAY NIGHT. STILL SOME QUESTION AS TO THE TIMING/SOUTHWARD MOVE OF THE FRONT...WITH THE NAM MORE PROGRESSIVE THAN OTHER MODELS. THIS MAY HAVE MORE OF AN IMPACT ON MAXS FOR CENTRAL KANSAS ON FRIDAY...AND FOR NOW WILL STILL KEEP THINGS QUITE TOASTY...HOWEVER AREAS OF SOUTH CENTRAL LOOK TO BE THE HOTTEST...ESPECIALLY FOR AREAS WEST AND SOUTHWEST OF GREATER WICHITA WHERE PERHAPS A DRIER SOUTHWEST FLOW AND SOME COMPRESSIONAL WARMING EFFECTS WILL ENHANCE MAX POTENTIAL LATE IN THE AFTERNOON. OTHERWISE...HAVE TEMPERED MAXS FOR THE WEEKEND...ESPECIALLY FOR SUNDAY...WITH MODEL CONSENSUS SUGGESTING RELATIVELY COOLER AIR WILL HOLD SWAY THRU THE WEEKEND NOW. DARMOFAL && .AVIATION... 06Z TAFS...ICT/SLN/HUT/CNU/RSL...VFR CONDITIONS ANTICIPATED OVER THE NEXT 24 HOURS. STRENGTHENING AND VEERING LOW-LEVEL JET TONIGHT MAY INITIATE A STRAY THUNDERSTORM SOMEWHERE ACROSS CENTRAL AND SOUTHEAST KANSAS TONIGHT...BUT PREDICTABILITY IS TOO LOW AND COVERAGE TOO SPARSE TO MENTION VCTS IN THE TAFS. OTHERWISE...STOUT SOUTHERLY WINDS WILL COMMENCE BY MID-MORNING THURSDAY...AS LOW PRESSURE STRENGTHENS ACROSS THE WESTERN HIGH PLAINS...AND A COLD FRONT GETS ITS ACT TOGETHER NORTHWEST OF THE AREA. KLEINSASSER && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 95 73 97 71 / 10 10 20 50 HUTCHINSON 96 72 98 69 / 10 10 30 50 NEWTON 95 73 97 70 / 10 10 30 50 ELDORADO 94 73 95 71 / 10 10 20 60 WINFIELD-KWLD 94 73 96 72 / 10 10 20 60 RUSSELL 100 71 95 66 / 10 20 40 20 GREAT BEND 99 71 97 67 / 10 10 40 30 SALINA 99 73 97 68 / 10 20 40 40 MCPHERSON 97 73 97 69 / 10 10 40 40 COFFEYVILLE 92 72 93 72 / 10 10 20 60 CHANUTE 92 72 93 72 / 10 20 20 60 IOLA 92 72 93 72 / 10 20 20 60 PARSONS-KPPF 92 72 93 72 / 10 10 20 60 && .ICT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 227 PM EDT THU JUN 26 2008 .SHORT TERM.../THE REST OF TODAY/ THE MAIN FOCUS FOR THE UPDATE THIS MORNING WILL DEAL WITH THE THREAT FOR AFTERNOON THUNDERSTORMS. THE MAIN CHANGE TO POPS WAS TO ADD A FEW MORE COUNTIES A LITTLE FURTHER SOUTH IN THE CHANCE POP RANGE. CURRENT WATER VAPOR IMAGERY/RUC 13 SHOW THE POTENTIAL FOR AN APPROACHING WEAK SHORT WAVE TO INFLUENCE COUNTIES MAINLY NORTH OF INTERSTATE 64. THE FEELING IS THAT SCATTERED COVERAGE WOULD REPRESENT THE AREA INFLUENCED BY THE WAVE AND ISOLATED COVERAGE WOULD REPRESENT THE AREAS FURTHER SOUTH WHO NEED TO REACH THEIR CONVECTIVE TEMPS. LAPS AND FORECAST SOUNDINGS SHOW A WEAK WIND PROFILE THROUGH THE ENTIRE COLUMN...SO ANY ORGANIZED THUNDERSTORMS WOULD BE VERY HARD TO COME BY. THE BEST CHANCE FOR ANY ORGANIZATION WOULD BE IN THE NORTH WHERE BETTER FORCING FOR ASCENT WILL BE ASSOCIATED WITH THE WEAK SHORTWAVE. CURRENT SURFACE OBS SHOW 14Z TEMPERATURES WELL ON THEIR WAY TO THE UPPER 80S TO AROUND 90 DEGREES. DID NOT CHANGE MUCH IN THE WAY OF TEMPERATURES...ONLY MADE A FEW MINOR TWEAKS BASED ON CURRENT TRENDS. EXPECT MOISTURE TO CONTINUE TO INCREASE TODAY...SETTING UP THE APPROACHING WEEKEND SYSTEM. UPDATED ZFP OUT SHORTLY. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /TODAY THROUGH FRIDAY NIGHT/ MOISTURE RETURN WILL GRADUALLY INCREASE ACROSS EASTERN KENTUCKY TODAY AS UPPER RIDGE WEAKENS AND MOVES OFF TO THE EAST AND SOUTHEAST. FLOW PATTERN WILL TRANSITION TO MORE ZONAL...LEAVING US OPEN TO MORE EMBEDDED WEAK SHORT WAVES. HAVE MAINTAINED ISOLATED POPS FOR ALL TODAY WITH CONVECTIVE TEMPERATURES LIKELY BEING REACHED FOR SOME. BETTER CHANCE WILL EXIST IN THE BLUEGRASS COUNTIES CLOSER TO THE TRAIN OF TRAVERSING WEAK DISTURBANCES ALONG WITH AMPLE MOISTURE RETURN...SO HAVE GONE WITH SCATTERED CONVECTION IN THE AFTERNOON. STUCK CLOSER TO THE NAM MOS FOR HIGHS AT JKL...WHILE USING THE GFS MOS FOR LOZ AND SME. SCATTERED CONVECTION WILL RE-FIRE FRIDAY AFTERNOON INTO FRIDAY EVENING AS WE BECOME MORE UNDER THE INFLUENCE OF TROUGHING TAKING PLACE ACROSS THE NORTHERN PLAINS WITH ADDITIONAL WEAK DISTURBANCES MOVING TOWARDS THE AREA. INCREASED CLOUD COVER WILL KEEP HIGHS A BIT COOLER ON FRIDAY...HOWEVER CONTINUED MOISTURE ADVECTION WILL KEEP THE AIR MASS VERY MUGGY. USED A BLEND OF PERSISTENCE AND THE LATEST GUIDANCE FOR TEMPERATURES FROM TONIGHT THROUGH FRIDAY NIGHT. .LONG TERM.../SATURDAY THROUGH WEDNESDAY/ THE MAIN FOCUS FOR THE LONG TERM FORECAST PERIOD WILL DEAL THE APPROACH AND ARRIVAL OF A COLD FRONT ASSOCIATED WITH AN UNSEASONABLY STRONG UPPER LEVEL LOW TO THE NORTHWEST. HAVE DECIDED TO BLEND BETWEEN THE GFS/ECMWF SOLUTIONS AS SLOWER AND MORE SOUTHERLY TRACK SEEMS TO BE THE WAY TO GO. THE LATEST HPC DISCUSSIONS SEEMS TO AGREE WITH THIS DECISION AS WELL. AS A RESULT...HAVE SLOWED THE SYSTEM DOWN WHICH WILL GIVE US PRETTY GOOD CHANCES FOR RAIN...POSSIBLY HEAVY AT TIMES...STARTING SATURDAY AND ENDING SUNDAY AFTERNOON. AN INTERESTING SETUP WITH SURFACE HIGH PRESSURE OFF THE SOUTHEAST COAST SHOULD PROVIDE PLENTY OF MOISTURE RETURN AHEAD OF THE SYSTEM ON SATURDAY. UPLIFT FROM MULTIPLE WAVES EMBEDDED IN THE HIGHLY AMPLIFIED H5 TROUGH WILL ALLOW FOR CONTINUING CHANCES OF PRECIPITATION. HAVE SLIGHTLY INCREASED POPS TO GOOD CHANCE AND LIKELY FOR MOST OF THE EVENT. LATEST GUIDANCE VALUES ALSO CAME IN WITH HIGHER POPS ADDING CONFIDENCE TO THE FORECAST. BASED ON NAM/GFS FORECAST SOUNDINGS...SOME CONCERN IS STARTING TO GROW WITH REGARD TO HEAVY RAINFALL POSSIBLE LATE SATURDAY AFTERNOON AND NIGHT. VERY MOIST/TROPICAL LIKE SOUNDINGS SHOW TALL SKINNY CAPE PROFILES AND PWAT VALUES AROUND 2 INCHES ON SATURDAY. SOUTHWEST TO NORTHEAST LINEAR FORCING ASSOCIATED WITH THE FRONT AND FAIRLY SLOW STORM MOTIONS PARALLEL TO THIS COULD RESULT IN TRAINING OF VERY EFFICIENT THUNDERSTORMS. WILL HAVE TO MONITOR THIS SITUATION CLOSELY AND KEEP THE NAM MOISTURE BIAS IN MIND. HAVE DECIDED TO MENTION THE POSSIBILITY OF THE THREAT FOR LOCALLY HEAVY RAINFALL IN THE HWO. THE COLD FRONT FINALLY MOVES THROUGH SOMETIME ON SUNDAY WITH POPS ENDING LATE SUNDAY AFTERNOON. HAVE KEPT THE REST OF THE EXTENDED DRY FOR NOW...HOWEVER LINGERING MOISTURE AND ANY WAVES EMBEDDED IN THE RETREATING H5 TROUGH COULD ALLOW FOR SOME VERY ISOLATED COVERAGE. TOO MUCH UNCERTAINTY EXISTS AT THIS POINT TO INCLUDE SLIGHT CHANCE POPS. AS FAR AS TEMPERATURES GO...DID NOT MAKE MANY CHANGES. ONLY MADE A FEW MINOR ADJUSTMENTS BASED ON LATEST GUIDANCE VALUES. && .AVIATION.../18Z TO 18Z/...UPDATED ISOLATED THUNDERSTORMS HAVE DEVELOPED OVER THE AREA AND EXPECT THESE TO CONTINUE INTO EARLY EVENING BUT SHOULD NOT INCREASE COVERAGE MUCH. WILL UPDATE TAFS THIS AFTERNOON ONLY IF A CLUSTER OF STORMS APPROACHES. BELIEVE VCTS WILL SUFFICE. OTHERWISE THINK THERE IS ENOUGH RIDGE REMAINING ONCE THE HEATING IS LOST TO KEEP THUNDER FROM APPROACHING WITH THE SHORTWAVE FROM IL LATE TONIGHT. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...GEOGERIAN/SCHOETTMER LONG TERM....SCHOETTMER AVIATION...GV ky AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON KY 1043 AM EDT THU JUN 26 2008 .SHORT TERM.../THE REST OF TODAY/...UPDATED THE MAIN FOCUS FOR THE UPDATE THIS MORNING WILL DEAL WITH THE THREAT FOR AFTERNOON THUNDERSTORMS. THE MAIN CHANGE TO POPS WAS TO ADD A FEW MORE COUNTIES A LITTLE FURTHER SOUTH IN THE CHANCE POP RANGE. CURRENT WATER VAPOR IMAGERY/RUC 13 SHOW THE POTENTIAL FOR AN APPROACHING WEAK SHORT WAVE TO INFLUENCE COUNTIES MAINLY NORTH OF INTERSTATE 64. THE FEELING IS THAT SCATTERED COVERAGE WOULD REPRESENT THE AREA INFLUENCED BY THE WAVE AND ISOLATED COVERAGE WOULD REPRESENT THE AREAS FURTHER SOUTH WHO NEED TO REACH THEIR CONVECTIVE TEMPS. LAPS AND FORECAST SOUNDINGS SHOW A WEAK WIND PROFILE THROUGH THE ENTIRE COLUMN...SO ANY ORGANIZED THUNDERSTORMS WOULD BE VERY HARD TO COME BY. THE BEST CHANCE FOR ANY ORGANIZATION WOULD BE IN THE NORTH WHERE BETTER FORCING FOR ASCENT WILL BE ASSOCIATED WITH THE WEAK SHORTWAVE. CURRENT SURFACE OBS SHOW 14Z TEMPERATURES WELL ON THEIR WAY TO THE UPPER 80S TO AROUND 90 DEGREES. DID NOT CHANGE MUCH IN THE WAY OF TEMPERATURES...ONLY MADE A FEW MINOR TWEAKS BASED ON CURRENT TRENDS. EXPECT MOISTURE TO CONTINUE TO INCREASE TODAY...SETTING UP THE APPROACHING WEEKEND SYSTEM. UPDATED ZFP OUT SHORTLY. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /TODAY THROUGH FRIDAY NIGHT/ MOISTURE RETURN WILL GRADUALLY INCREASE ACROSS EASTERN KENTUCKY TODAY AS UPPER RIDGE WEAKENS AND MOVES OFF TO THE EAST AND SOUTHEAST. FLOW PATTERN WILL TRANSITION TO MORE ZONAL...LEAVING US OPEN TO MORE EMBEDDED WEAK SHORT WAVES. HAVE MAINTAINED ISOLATED POPS FOR ALL TODAY WITH CONVECTIVE TEMPERATURES LIKELY BEING REACHED FOR SOME. BETTER CHANCE WILL EXIST IN THE BLUEGRASS COUNTIES CLOSER TO THE TRAIN OF TRAVERSING WEAK DISTURBANCES ALONG WITH AMPLE MOISTURE RETURN...SO HAVE GONE WITH SCATTERED CONVECTION IN THE AFTERNOON. STUCK CLOSER TO THE NAM MOS FOR HIGHS AT JKL...WHILE USING THE GFS MOS FOR LOZ AND SME. SCATTERED CONVECTION WILL RE-FIRE FRIDAY AFTERNOON INTO FRIDAY EVENING AS WE BECOME MORE UNDER THE INFLUENCE OF TROUGHING TAKING PLACE ACROSS THE NORTHERN PLAINS WITH ADDITIONAL WEAK DISTURBANCES MOVING TOWARDS THE AREA. INCREASED CLOUD COVER WILL KEEP HIGHS A BIT COOLER ON FRIDAY...HOWEVER CONTINUED MOISTURE ADVECTION WILL KEEP THE AIR MASS VERY MUGGY. USED A BLEND OF PERSISTENCE AND THE LATEST GUIDANCE FOR TEMPERATURES FROM TONIGHT THROUGH FRIDAY NIGHT. .LONG TERM.../SATURDAY THROUGH WEDNESDAY/ THE MAIN FOCUS FOR THE LONG TERM FORECAST PERIOD WILL DEAL THE APPROACH AND ARRIVAL OF A COLD FRONT ASSOCIATED WITH AN UNSEASONABLY STRONG UPPER LEVEL LOW TO THE NORTHWEST. HAVE DECIDED TO BLEND BETWEEN THE GFS/ECMWF SOLUTIONS AS SLOWER AND MORE SOUTHERLY TRACK SEEMS TO BE THE WAY TO GO. THE LATEST HPC DISCUSSIONS SEEMS TO AGREE WITH THIS DECISION AS WELL. AS A RESULT...HAVE SLOWED THE SYSTEM DOWN WHICH WILL GIVE US PRETTY GOOD CHANCES FOR RAIN...POSSIBLY HEAVY AT TIMES...STARTING SATURDAY AND ENDING SUNDAY AFTERNOON. AN INTERESTING SETUP WITH SURFACE HIGH PRESSURE OFF THE SOUTHEAST COAST SHOULD PROVIDE PLENTY OF MOISTURE RETURN AHEAD OF THE SYSTEM ON SATURDAY. UPLIFT FROM MULTIPLE WAVES EMBEDDED IN THE HIGHLY AMPLIFIED H5 TROUGH WILL ALLOW FOR CONTINUING CHANCES OF PRECIPITATION. HAVE SLIGHTLY INCREASED POPS TO GOOD CHANCE AND LIKELY FOR MOST OF THE EVENT. LATEST GUIDANCE VALUES ALSO CAME IN WITH HIGHER POPS ADDING CONFIDENCE TO THE FORECAST. BASED ON NAM/GFS FORECAST SOUNDINGS...SOME CONCERN IS STARTING TO GROW WITH REGARD TO HEAVY RAINFALL POSSIBLE LATE SATURDAY AFTERNOON AND NIGHT. VERY MOIST/TROPICAL LIKE SOUNDINGS SHOW TALL SKINNY CAPE PROFILES AND PWAT VALUES AROUND 2 INCHES ON SATURDAY. SOUTHWEST TO NORTHEAST LINEAR FORCING ASSOCIATED WITH THE FRONT AND FAIRLY SLOW STORM MOTIONS PARALLEL TO THIS COULD RESULT IN TRAINING OF VERY EFFICIENT THUNDERSTORMS. WILL HAVE TO MONITOR THIS SITUATION CLOSELY AND KEEP THE NAM MOISTURE BIAS IN MIND. HAVE DECIDED TO MENTION THE POSSIBILITY OF THE THREAT FOR LOCALLY HEAVY RAINFALL IN THE HWO. THE COLD FRONT FINALLY MOVES THROUGH SOMETIME ON SUNDAY WITH POPS ENDING LATE SUNDAY AFTERNOON. HAVE KEPT THE REST OF THE EXTENDED DRY FOR NOW...HOWEVER LINGERING MOISTURE AND ANY WAVES EMBEDDED IN THE RETREATING H5 TROUGH COULD ALLOW FOR SOME VERY ISOLATED COVERAGE. TOO MUCH UNCERTAINTY EXISTS AT THIS POINT TO INCLUDE SLIGHT CHANCE POPS. AS FAR AS TEMPERATURES GO...DID NOT MAKE MANY CHANGES. ONLY MADE A FEW MINOR ADJUSTMENTS BASED ON LATEST GUIDANCE VALUES. && .AVIATION.../12Z TO 12Z/ WEAK UPPER RIDGE WILL WORK TO KEEP CONVECTION TO A MINIMUM OVER EAST KENTUCKY AGAIN TODAY. HOWEVER...CANNOT RULE OUT A STRAY SHOWER OR THUNDERSTORM...ACCORDINGLY KEPT THE MODERATELY HIGH BASED CB SCT GROUP IN THE TAFS FROM EARLY AFTERNOON INTO THE EVENING. OTHERWISE... HIGH CIRRUS CLOUDS WILL DRIFT THROUGH THE AREA. SIMILAR TO WEDNESDAY WINDS WILL BE LIGHT THROUGH THE PERIOD GENERALLY FROM THE SOUTHWEST. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...GEOGERIAN/SCHOETTMER LONG TERM....SCHOETTMER AVIATION...GREIF ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CARIBOU ME 412 AM EDT THU JUN 26 2008 .SYNOPSIS... A WEAK COLD FRONT WILL WILL STALL ACROSS THE REGION THURSDAY. A WAVE OF LOW PRESSURE WILL TRACK ALONG THE FRONT THIS AFTERNOON AND MOVE EAST OF THE REGION ON FRIDAY. HIGH PRESSURE WILL THEN BUILD TOWARD THE AREA OVER THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... MAIN CHALLENGES ARE POSITIONING OF THE FRONT AND THE POTENTIAL FOR SVR WX. DECIDED ON A BLEND OF THE GFS AND SREF FROM THIS AFTERNOON INTO TONIGHT. THE RUC13 AND GFS40 WAS USED TO START THINGS OFF THIS MORNING W/1ST BATCH OF LIGHT RAIN SHOWERS MOVING E AND EXITING INTO NEW BRUNSWICK. THE FRONTAL BOUNDARY IS FCST TO SLOWLY SAG S TODAY AS A WAVE OF LOW PRES MOVES IN ALONG THE BOUNDARY FROM CNTL CANADA. LOOKS LIKE THERE COULD BE THE POTENTIAL FOR 2 AREAS OF CONVECTION W/THE 1ST AREA GETTING STARTED LATER THIS MORNING INTO EARLY AFTERNOON ACROSS THE N AND W AND THEN A 2ND AREA FIRING UP ACROSS CNTL AND DOWNEAST AREAS. SATL IR IMAGERY SHOWING TO POTENTIAL FOR SOME INSOLATION THIS MRNG ACROSS THE N AND W IN BTWN S/WVS ALLOWING FOR DESTABILIZATION. CNTL AND DOWNEAST AREAS SHOULD BE ALLOWED TO HEAT UP THIS AFTERNOON. DWPTS ARE PROGGED TO INCREASE INTO THE LOWER AND MID 60S BY THIS AFTERNOON. GFS SOUNDINGS SHOWING MU CAPES HITTING 1000+ J/KG LATER THIS MORNING INTO EARLY AFTERNOON FOR THE N AND W AND THEN THINGS TRANSLATE INTO CNTL AND DOWNEAST BY MID-AFTERNOON. TTS HIT AROUND 50 W/KIS CLOSING IN 35 W/LIS DROPPING TO -4 TO -6. PWS AROUND 1.5". 0-6KM SHEAR IS ABOUT 25 KTS COUPLED W/INVERTED V IN LLVLS INDICATING DOWNDRAFT POTENTIAL. UA SHOWED 30-40 KT JETLET FROM 700-500 MBS TO CROSS THE REGION THIS MORNING AS WELL. ONE LACKING INGREDIENT IS STEEP LAPSE RATES. LAPSE ARE EXPECTED TO BE MEAGER W/VALUES AROUND 6.0 C/KM. SPC HAS BACKED OFF ON THE SLIGHT RISK POTENTIAL FOR OUR CWA AND NOW OUR CWA IS IN A GENERAL RISK. AFTER PHONE CHAT W/GYX...DECIDED TO ADD ENHANCED WORDING FOR HAIL AND GUSTY WINDS. INCREASING CONCERNS ARE THERE FOR THE POTENTIAL FOR HEAVY RAFL W/HIGH PWS AND LOW/MID FLOW PARALLELING THE FRONT. REGENERATION OF CELLS COULD LEAD TO THE POTENTIAL FOR SOME FLOODING ISSUES. THIS WILL NEED TO BE MONITORED. CONVECTION WILL WIND DOWN THIS EVENING AND HEAVY RAFL AXIS IS EXPECTED TO SHIFT INTO NEW BRUNSWICK AFT 06Z AS SFC LOW PASSES TO THE E. USED THE DAYCREW/S TEMPS AS THEY WERE MATCHING WELL W/THE LATEST OBS. ADJUSTMENTS WERE MADE TO THE WIND FIELDS TAKING A BLEND OF THE NAM12 AND GFS40. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... A COLD FRONT IS EXPECTED TO MOVE INTO NORTHERN PORTION OF THE STATE FRIDAY MORNING ALTHOUGH IT IS QUESTIONABLE HOW FAR TO THE SOUTH THE FRONT WILL MOVE FROM THAT POINT ON. FOR SATURDAY LOW PRESSURE ALOFT AND AT THE SURFACE APPROACH FROM THE GREAT LAKES. WILL GENERATE POP GRIDS WITH A BLEND OF THE SERF...GS40 AND NAM12. SKY GRIDS CREATED WITH A BLEND OF THE NAM12 AND GS40. FOR TEMPERATURE AND DEW POINT WILL INITIALIZE WITH GM OS. HAVE RAISED MAX TEMPERATURES A FEW DEGREES ABOVE GM OS. WILL MENTION SCATTERED THUNDERSTORMS FOR BOTH SATURDAY AND SUNDAY AFTERNOONS INTO THE EVENING. FOR PF HAVE USED A NAM12/GS40 BLEND. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... LOW PRESSURE IS EXPECTED TO APPROACH FROM THE WEST AT THE BEGINNING OF THIS PERIOD. THIS SYSTEM WILL SLOWLY MOVE TO THE NORTHEAST THRU TUESDAY AND WEDNESDAY. HAVE GENERATED GRIDS FOR THIS PERIOD USING GMOS. FOR SKY GRIDS HAVE MANUALLY ADJUSTED SOME PERIODS TO BETTER FIT POPS. WILL PUT MENTION OF THUNDER INTO SUNDAY AFTERNOON/EVENING PERIODS. && .AVIATION /07Z THURSDAY THROUGH MONDAY/... NEAR TERM: VFR TO START THINGS OUT TODAY AND THEN WE ARE EXPECTING CONDITIONS TO DROP INTO MVFR CATEGORY LATER THIS AFTERNOON W/RAFL AND POSSIBLE TSTMS. MVFR CONDITIONS LOOK TO HOLD INTO TONIGHT. LOOKING FURTHER OUT: EXPECT PERIODS OF MVFR/IFR CONDITIONS FROM FRIDAY INTO MONDAY. && .MARINE... NEAR TERM: NO HEADLINES. AS MENTIONED ABV...USED A GFS40/NAM12 BLEND FOR THE WINDS WILL INDICATES SPEEDS OF 10 KT INTO TONIGHT. WNAWAVE WAS LOADED FOR THE WAVE HEIGHTS AND THEN ADJUSTED DOWNWARD BY A FOOT AS IT IS ALREADY 1 FOOT OVER THE LATEST OBS. SHORT TERM: HAVE INITIALIZED WIND GRIDS WITH A 50/50 BLEND OF THE NAM12 AND THE GFS40. WIND SPEEDS LOOK REASONABLE AND WILL NOT MAKE ANY CHANGES. FOR WINDS AFTER 00Z SUNDAY WILL USE GMOS WINDS. FOR WAVES: HAVE INITIALIZED INTO SATURDAY WITH NAM VERSION OF SWAN. FOR REMAINDER OF PERIOD WILL INITIALIZE WITH WNA. IN GENERAL SEEMS TO BE HIGH BIAS FOR BEGINNING OF PERIOD SO WILL LOWER BY 1 FOOT. FOR SUNDAY INTO TUESDAY WNA RUNNING MUCH TOO HIGH AND HAVE LOWERED WAVE HEIGHTS SEVERAL FEET. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...NONE. && $$ NEAR TERM...HEWITT SHORT TERM...MIGNONE LONG TERM...MIGNONE AVIATION...HEWITT MARINE...HEWITT/MIGNONE me AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CARIBOU ME 1028 AM EDT WED JUN 25 2008 .SYNOPSIS... HIGH PRESSURE WILL SLIDE SOUTH OF THE AREA TODAY AS A WEAK FRONTAL BOUNDARY MOVES DOWN FROM THE NORTHWEST. THE FRONT WILL STALL ACROSS THE REGION TONIGHT. A WAVE OF LOW PRESSURE TRACKING ALONG THE FRONT WILL APPROACH ON THURSDAY AND TRACK ACROSS THE AREA THURSDAY NIGHT. THE LOW WILL MOVE EAST ON FRIDAY FOLLOWED BY COOLER HIGH PRESSURE OVER THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... BASED ON LATEST RADAR AND SATELLITE TRENDS HAVE REMOVED ANY REFERENCE TO SHOWERS ACROSS THE NORTH THIS AFTERNOON. CANADIAN RADAR MOSAIC AND OBSERVATIONS ARE CURRENTLY SHOWING ANY SHOWER ACTIVITY WELL BACK ACROSS NORTHWEST QUEBEC PROVINCE. LATEST RUC SEEMS TO HAVE A GOOD HANDLE ON THE SITUATION AND KEEPS THE US DRY THROUGH THIS AFTERNOON. MOISTURE ASSOCIATED WITH ANOTHER SHORTWAVE AND ASSOCIATED LOW WILL THEN BEGIN SPREADING INTO THE REGION LATE TONIGHT WITH SOME SHOWERS MOVING INTO THE AREA TOWARD MORNING. && .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... ANOTHER ROUND OF WET WX IS IN STORE THIS PERIOD. THE MAIN CHALLENGES WILL BE THE FRONTAL BOUNDARY DROPPING S ACROSS THE CWA AND WAVE OF LOW PRES MOVING ALONG THE BOUNDARY. CONCERNS ARE...WHERE TO PLACE CONVECTION AND TRACK OF SFC LOW. DECIDED ON A 33% BLEND OF THE SREF/GFS40 AND NAM INTO THURSDAY EVENING AND THEN WENT W/THE SREF/GFS40 MATCHING THIS BLEND W/THE ECMWF AS SFC LOW TRACKS THROUGH CNTL MAINE AND NOT AS FAR N AS THE NAM HAS IT ACROSS NERN MAINE. THEREFORE...PUSHED POPS UP TO LIKELY AND CATEGORICAL ACROSS MOST OF THE CWA INTO THURSDAY EVENING W/THE EXCEPTION OF THE COAST AS HIGH CHC POPS WERE USED. AIRMASS LOOKS STABLE ENOUGH ACROSS THE NRN 1/2 OF THE CWA TO GO W/STRATIFORM RAIN W/AN ESE FLOW. FURTHER S ACROSS CNTL AND DOWNEAST AREAS...ADDED THE MENTION OF TSTMS THURSDAY AFTERNOON INTO THURSDAY EVENING AS MDL SOUNDINGS INDICATE HIGHEST INSTABILITY IN THESE AREAS. NEED TO BE AWARE OF HEAVY RAFL ESP WHERE CONVECTION OCCURS AS KIS ARE FCST TO PUSH MID 30S...PWS TO BE AT 1.5 INCHES AND DECENT ESE INFLOW OVERRIDING THE FRONTAL BOUNDARY. AREAL QPF AMOUNTS ARE A BLEND OF THE SREF/HPC AND GFS WHICH YIELD ANYWHERE FROM .50-.75 INCHES ACROSS NRN AND CNTL AREAS TO AROUND .25 OF AN INCH. HIGHER AMOUNTS OF COURSE CAN BE EXPECTED IN HEAVIER RAFL ESP IN CONVECTION. ADDED TSTMS AGAIN FOR CNTL AND DOWNEAST AREAS DUE TO PROXIMITY OF THE FRONT AND 30-35 KT MID-LVL JET PROGGED TO MOVE ACROSS THESE AREAS. KEPT DAYCREWS THURSDAY MAXES AS THEY MATCH CLOSE TO LATEST GUIDANCE NUMBERS. FRIDAY/S MAXES WERE ADJUSTED DOWNWARD TO THE MID 60S ACROSS NRN MAINE WHERE ELY FLOW WILL KEEP CLOUDS AND RAFL LIMITING MUCH WARMING. && .LONG TERM /FRIDAY THROUGH TUESDAY/... GMOS WAS LOADED AND THEN ADJUSTED COMPARING IT TO THE LATEST ECMWF AND GFS ENS. BIGGEST CONCERN IS FOR THE WEEKEND AS THE LATEST ECMWF HAS NOW BECOME MORE AGGRESSIVE W/BRINGING RAFL INTO THE CWA BY SATURDAY NIGHT WHILE THE OPERATIONAL GFS40 HAS HIGH PRES DROPPING DOWN ACROSS THE CWA. CONFIDENCE NOT THAT HIGH GIVEN SUCH A DISPARITY. HOWEVER...THE LATEST GFS ENS DOES SHOW SOME SUPPORT OF THE OPERATIONAL GFS40. THEREFORE...DECISION WAS TO LEAN W/A DRIER SCENARIO FOR SATURDAY INTO EARLY SUNDAY KEEPING CHC POPS ACROSS THE SRN TIER OF THE CWA BY SUNDAY AFTERNOON. HIGH PRES RIDGE SHOWS SIGNS OF BREAKING DOWN AND SHIFTING E BY SUNDAY NIGHT. LOW PRES IS FCST TO TRACK THROUGH WRN QUEBEC ON MONDAY BRINGING A FRONTAL BOUNDARY ACROSS THE REGION W/INCREASING CHCS FOR SHOWERS AND POSSIBLE TSTMS. GMOS POPS SHOWED 40% FOR THE CWA MONDAY INTO TUESDAY AND ATTM SAW NO REASON TO DEVIATE FROM THEM. A MODEST ADJUSTMENT WAS MADE TO THE TEMPERATURES ESP MINIMUMS AS CLOUDS AND SSW FLOW WILL ALLOW FOR A MORE HUMID AIRMASS TO RETURN. && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/... NEAR TERM: VFR CONDITIONS ARE EXPECTED ACROSS THE AREA TODAY. CONDITIONS MAY LOWER TO IFR ACROSS THE NORTH LATE TONIGHT BUT REMAIN VFR OVER DOWNEAST AREAS. SHORT TERM: LOOKS LIKE IFR/MVFR CONDITIONS RIGHT INTO THURSDAY NIGHT AS THE FRONTAL BOUNDARY DROPS S. SOME IMPROVEMENT POSSIBLE LATER ON FRIDAY TO VFR AS THE FRONT SAGS FURTHER S AND SOME DRIER AIR RETURNS. LATEST INDICATIONS ARE THE VFR LOOKS GOOD INTO THE WEEKEND. && .MARINE... NEAR TERM: WINDS AND SEAS WILL REMAIN BELOW SCA TODAY AND TONIGHT. DRIER AIR WILL BRING GOOD VISIBILITIES TODAY. SHORTER TERM: NO HEADLINE ES FORESEEN ATTM. ADJUSTMENTS WERE MADE TO THE WNAWAVE ESP LAST FEW PERIODS TO LOWER WAVE HEIGHTS BACK 1-2 FT. LOOKS LIKE SWELL GENERATION AS ESE FLOW SETS UP. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...NONE. && $$ NEAR TERM...DUDA/BLOOMER SHORT TERM...HEWITT LONG TERM...HEWITT AVIATION...BLOOMER MARINE...BLOOMER/HEWITT me AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 229 PM EDT WED JUN 25 2008 .SYNOPSIS... HIGH PRESSURE CONTINUES TO BUILD OVER THE REGION THROUGH THIS EVENING...SHIFTING OFFSHORE THURSDAY INTO FRIDAY. A COLD FRONT APPROACHES THE REGION ON SATURDAY. && .NEAR TERM /THROUGH TONIGHT/... HIGH PRES OVER THE RGN WL CONTINUE TO DOMINATE WX TDA. DRY AIRMASS...PLENTY OF SUNSHINE AND RISING HGTS ALLOW TEMPS TO BE A FEW DEGREES WARMER THAN YDA. WENT WITH NAM/FWC BLEND (BLO WARM MAV GUIDANCE)...YIELDING HIGHS TDA INTO LWR 90S FOR MUCH OF INTERIOR VA/NC (SEE CLIMATE SECTION BELOW). COOLER U80S/ARND 90 AT IMMEDIATE COASTLINE (L/M80S IVOF OXB-WAL). WITH DRY DOWNSLOPE WINDS AND LOOKING AT MIXED LAYER RUC13 LOWERED DEWPOINTS IN THE WEST TO LOWER 50S OTHERWISE MID TO UPPER 50S DEWPOINTS. ALONG THE COAST DEWPOINTS IN THE 60S. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... HIGH PRES SHIFTS OFFSHORE ERY THU...ALLOWING RETURN FLOW TO STRENGTHEN. HIGHS EXPECTED AT LEAST IN THE MID 90S BOTH DAYS...WITH GUIDANCE AND LOCAL THICKNESS SCHEMES POINTING TWDS THU AS THE WARMEST DAY OF THE PERIOD. ONCE AGAIN APPLIED A MAV/FWC BLEND FOR MAX T...RESULTING IN MID 90S (WITH A FEW UPR 90S) INLAND THU...L/M 90S INTO TIDEWATER AND COASTAL LOCALES (XCEPT IMMEDIATE COASTLINE). THESE VALUES ARE AGAIN JUST BLO MAV GUID...BUT ARE A FEW DEGREES HIGHER THAN LOCAL TKNS SCHEMES WUD DICTATE. KEPT ISO WORDING FOR TSRA FOR BOTH AFTNS FOR SOME TYPICAL DIURNALLY DRIVEN CONVECTION. WHILE MIDLVL CAP APPEARS STRONG...BUT CAN`T RULE OUT A FEW RENEGADE STORMS POPPING UP (PWATS INCREASE MODESTLY BY THU AFTN). SPC HAS SRN HALF OF CWA IN GENERAL TSTM AREA FOR THU. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... VRY WRM AND RATHER HUMID THRU THE PERIOD WITH GENERALLY SLGT OR SML CHCS FOR SHRAS/TSRAS FOR MUCH OF THE AREA THRU MON...DUE TO THE APPROACH AND SLOW PASSAGE OF A COLD FRNT. THE BNDRY WILL LIKELY MOVE OFF THE CST DURING TUE...SO HAVE SLGT OR SML CHCS IN ERN CNTIES. ALTHO TEMPS MAY END UP WRMER...GOING WITH HI`S RANGING FM THE MID 80S TO LWR 90S AT THIS TIME. MIN TEMPS WILL GENERALLY RANGE FM THE MID 60S TO LWR 70S. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... SOUTH/SOUTHEASTERLY SURGE UP BAY TO AFFECT COASTAL SITES TONIGHT (ECG/ORF/PHF) WITH GUSTS UP TO 20 KTS AT ORF. OTW...SMOKE FROM THE TWO ONGOING FIRES THE MAIN CONCERN INTO THE WEEKEND. LIGHT AND VARIABLE WINDS THIS AFTN ARE KEEPING THE SMOKE PLUMES NEAR THE FIRES. SURGE THIS EVENING SHOULD BRING PLUME TO PHF...THEN A SWITCH TO SOUTHWESTERLY WINDS AFTER 04Z SHOULD BRING SMOKE TO ORF/ECG. CHANCE OF SUPER FOG AGAIN THUR MORN AT ECG/ORF...ESP IF WINDS/MIXING DIMINISH AND SKIES CLEAR TOWARDS 08Z. HIGH PRESSURE TO DOMINATE THE REGION...LIMITING CHANCES OF PRECIP/KEEPING VFR CONDS...INTO SATURDAY. NEXT CHANCE OF WIDESPREAD REDUCES AVN CONDS SATURDAY NIGHT THROUGH SUNDAY AHEAD OF CD FROPA. && .MARINE... SFC HI PRES RMNS OFFSHR AND IN CONTROL INTO THE WKND...RESULTING IN PREVAILING SSW FLO (AOB 15 KT). HAVE HOISTED SCA FLAGS FOR SRLY SURGE TONIGHT AS HIGH SLIPS OFFSHORE...WINDS ACROSS SRN CHES BAY TO GUST TO AROUND 20 KTS FROM 21Z TO 05Z. WK CDFNT APPROACHES FM THE NW SAT NGT/SUN. && .FIRE WEATHER... CURRENT SMOKE PLUMES MOVING NORTH FROM THE FIRES OVER PARTS OF HAMPTON ROADS AND INTO NORTHEAST NORTH CAROLINA. LOOKING AT TRAJECTORY FORECAST AND STREAMLINES SHOWS THE SEA BREEZES HOLDING THE SMOKE TO THE WEST UNTIL EVENING. BY TONIGHT WILL HAVE TO WATCH FOR MORE DENSE FOG FORMING WITH THE SMOKE TO REDUCE VISIBILITIES OVER LARGER AREAS. ISSUED NPW FOR DENSE SMOKE AS VISIBILITIES HAVE BEEN AROUND A MILE OR LESS IN SOME LOCATIONS. && .CLIMATE... LOOKS LIKE A HOT FINISH FOR JUNE (WHICH HAS ALREADY BEEN HOT). THROUGH THE 24TH...RIC AVG TEMP IS 78.2 F...AND ORF IS 78.3 F. BASED ON CURRENT FCST FOR NEXT 6 DAYS...APPEARS AS IF 2008 WILL RANK AS EITHER 2ND OR 3RD WARMEST ALL TIME FOR RICHMOND AND 3RD OR 4TH WARMEST ALL TIME AT NORFOLK. _______________5 HOTTEST JUNES (AVG TEMPERATURE)_______________ RANK........RICHMOND...........NORFOLK......... 1........79.2 F (1943)......80.1 F (1943) 2........78.8 F (1895)......79.5 F (1994) 3........78.4 F (1892)......78.8 F (1934) 4......**78.2 F (2008)**....78.5 F (1952) 5........78.1 F (1890)......78.48F (1989) OTHER NOTABLE POSSIBILITIES... .RICHMOND... ***AVG HIGH TEMPERATURE FOR THE MONTH WILL LIKELY BE HIGHEST ALL TIME (90.0 F IN 1984 IS CURRENTLY THE HIGHEST). ***IF THE NEXT 6 DAYS (25TH-30TH) ALL HIT 90F (OR HIGHER)...WILL THEN HAVE 20 DAYS OF 90+ THIS JUNE (WHICH WOULD TIE 1943 FOR THE MOST). .NORFOLK... ***AVG HIGH TEMPERATURE FOR MONTH HAS A CHANCE TO BE HIGHEST ALL TIME (88.8 F IN 1943 IS CURRENTLY THE HIGHEST). && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 1 AM EDT THURSDAY FOR ANZ630>632. && $$ SYNOPSIS...MAM NEAR TERM...JAB/MAM SHORT TERM...MAM LONG TERM...ALS/TMG AVIATION...BAJ MARINE...ALB/BAJ FIRE WEATHER...ALB CLIMATE...LKB md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1001 PM EDT THU JUN 26 2008 .UPDATE...LATEST RUC ANALYSIS AND IR/WV/RADAR IMAGERY SHOW A WEAK SURFACE LOW OVER THE THUMB OF MICHIGAN WITH SHALLOW COOL FRONT EXTENDING SW THROUGH SOUTHERN LAKE MICHIGAN AND NORTHERN ILLINOIS. WEAK SURFACE HIGH HAS NUDGED IN BEHIND THE FRONT ACROSS NORTHERN MICHIGAN...WHILE SHORTWAVE RIDGING AND CORRESPONDING SUBSIDENCE HAS DRIED THE REGION SUBSTANTIALLY ALOFT EXCEPT FOR CONVECTIVE DEBRIS CIRRUS. HOWEVER...COLUMN LOOKS TO MOISTEN IN EARNEST JUDGING BY 00Z UPSTREAM SOUNDINGS FROM GRB/MPX AHEAD OF A MCV OVER WESTERN WISCONSIN. DO NOT SEE MUCH OF A CHANCE OF PRECIP AS THIS MCV MOVES ACROSS CENTRAL AND SOUTHERN LOWER MICHIGAN OVERNIGHT...DUE TO A GENERAL LACK OF MOISTURE AND INSTABILITY...BUT IT WILL SERVE TO KEEP THE MORE CLOUDIER SKIES SOUTH OF M-72. A COUPLE OTHER NUISANT WX ITEMS TO DEAL WITH OVERNIGHT. FIRST...HIGHER DEWPOINT AIR MOVING OVER LAKE SUPERIOR HAS MAINTAINED MARINE FOG/STRATUS TOWARDS THE EASTERN PART OF THE LAKE...AND NW WINDS HAVE BEEN FUNNELING THE FOG/STRATUS ACROSS WHITEFISH BAY AND INTO THE SOO AT TIMES. WINDS SHOULD STAY PERSISTENT OUT OF THE NW FOR MOST OF THE NIGHT AND AM HARD PRESSED TO FIND A REASON FOR THE FOG/STRATUS TO DISSIPATE. SECOND...PORTIONS OF EASTERN UPPER/TIP OF THE MITT/NE LOWER DID NOT MIX OUT AS WELL AS LOCATIONS TO THEIR SW...AND MAY SEE PATCHY FOG DEVELOP LATE TONIGHT BARRING THE CLOUD COVER DOES NOT HINDER TEMPS TOO MUCH. OTHER THAN THESE MINOR CHANGES...JUST A FEW OTHER TWEAKS BUT JUST OF THE FORECAST IN GOOD SHAPE. MPC && .PREV DISCUSSION... /ISSUED 718 PM EDT THU JUN 26 2008/ AVIATION...QUIET NIGHT ON TAP FOR LOCAL TAF SITES AS JUST HIGH CLOUDS FROM THUNDERSTORMS OVER THE PLAINS MOVE OVER THE AREA. HOWEVER...MAY HAVE TO ADD LOWER VSBYS FOR THE TAFS SITES EARLY TOMORROW MORNING DUE TO GROUND FOG. STILL SOME UNCERTAINTY EXISTS IN REGARDS TO CLOUD COVER AND WILL SEE HOW TEMPS RESPOND THIS EVENING BEFORE ADDING FOG TO TAFS. OTHERWISE...WX GOES DOWNHILL TOMORROW AFTERNOON WHEN A WARM FRONT LIFTS NORTH OVER THE GREAT LAKES. SHOWERS AND THUNDERSTORMS WILL IMPACT TVC FIRST BY MID- AFTERNOON AND POSSIBLY PLN/APN BY LATE AFTERNOON WITH MVFR/IFR VSBYS AND POSSIBLY CIGS. MPC PREV DISCUSSION... /ISSUED 344 PM EDT THU JUN 26 2008/ DISCUSSION...COOL FRONT HAS PUSHED SE OF OUR CWA LATE THIS AFTERNOON...WITH HIGH PRESSURE...SUBSIDENCE AND DRIER AIR FILTERING INTO NRN MICHIGAN. LINGERING CU FIELD ACROSS THE SE HALF OF OUR CWA IS GRADUALLY DIMINISHING IN RESPONSE TO BUILDING HIGH PRESSURE. ISOLD WEAK CONVECTION IS STILL TRYING TO FIRE AROUND NRN SAGINAW BAY ALONG OUR SE BORDER...BUT IS HAVING A HARD TIME STAYING TOGETHER AS IT SUCCUMBS TO INCREASING SUBSIDENCE AND STABILITY. ONE MORE QUIET NIGHT IS EXPECTED FOR NRN MICHIGAN BEFORE CONVECTION AGAIN GEARS UP ON FRIDAY AHEAD OF STRONG LOW PRESSURE...WITH WAVES OF CONVECTION EXPECTED TO IMPACT OUR AREA THRU MUCH OF THE WEEKEND AS THE LOW STALLS OVER THE WRN GREAT LAKES. TONIGHT...ANY REMAINING WEAK CONVECTION AROUND SAGINAW BAY SHOULD COME TO A CLOSE BEFORE 00Z. THEREAFTER...MAINLY CLEAR SKIES AND DRY WX CAN BE EXPECTED THRU TONIGHT. MID AND HIGH CLOUDS WILL BEGIN TO INCREASE ACROSS THE SW CWA OVERNIGHT IN ADVANCE OF A WARM FRONT LIFTING INTO THE WRN GREAT LAKES. LOW TEMPS OVERNIGHT WILL DROP INTO THE MID 50S TO LOWER 60S. FRIDAY...WARM FRONT WILL SLOWLY LIFT NE INTO OUR AREA...REACHING A LINE FROM THE ARROWHEAD OF MINNESOTA TO GREEN BAY TO SE LOWER MICHIGAN BY 00Z SATURDAY. AMPLE MOISTURE (1000-500 MB RH OF 90 PCT) WILL POOL ALONG AND NORTH OF THE FRONT...MAINLY DURING THE AFTERNOON. PLENTY OF LIFT TO GO AROUND...WITH AN ELONGATED AREA OF DPVA AND ISENTROPIC ASCENT (I305) DEVELOPING NORTH OF THE FRONT AS IT LIFTS INTO OUR CWA. ENHANCED 850 MB THETA E VALUES WILL ADVECT INTO THE REGION AS WELL. WIND FIELDS WILL INITIALLY BE WEAK FRIDAY MORNING...BUT WILL GRADUALLY STRENGTHEN DURING THE AFTERNOON. LL JET MAX WILL NOSE INTO LOWER MICHIGAN LATER IN THE DAY...AS 850 MB WINDS INCREASE TO 30-40 KTS. SEE NO REASON TO STRAY FROM CHANCE POPS CREEPING INTO LOCATIONS ALONG AND SOUTH OF M-72 DURING THE MORNING...SHRA/TSRA BECOMING LIKELY IN THE SW HALF OF OUR CWA IN THE AFTERNOON. NE HALF WILL SE CHANCE POPS IN THE AFTERNOON SLIGHTLY FARTHER AWAY FROM BETTER MOISTURE AND LIFT IMMEDIATELY NORTH OF THE WARM FRONT. REGARDING SVR WX POTENTIAL...BEST CHANCE WILL LIKELY BE LATER IN THE AFTERNOON AS WIND FIELDS STRENGTHEN...BEST DESTABILIZATION IS OCCURRING WITH PEAK HEATING AND FRONT IS NEARING SRN SECTIONS OF OUR CWA. HIGH TEMPS WILL BE MAINLY IN THE UPPER 70S AND LOWER 80S. LONG TERM...LOOKS TO BE A STORMY WEEKEND WITH A BREAK IN THE EARLY TO MID PART OF NEXT WEEK AND THEN A CHANCE FOR ANOTHER ROUND OF RAIN SHOWERS OR THUNDERSTORMS. TRIED TO MAKE SOME DISTINCTION BETWEEN RAIN AND NO RAIN OVER THE WEEKEND, BUT WITH THE GFS SUFFERING FROM CONVECTIVE FEEDBACK, ESPECIALLY SATURDAY OVER THE LOWER PENINSULA, TRIED TO BLEND LEANING TOWARD THE LESS CONTAMINATED MODEL, THE NAM FOR GUIDANCE. FRIDAY NIGHT/SATURDAY...INITIALLY, THE MODELS LOOK SIMILAR THROUGH ABOUT 06Z, WITH THE WARM FRONT MOVING UP THROUGH N LOWER. IT LOOKS LIKE THE RAIN SHOULD MOVE FROM SW TO NE THROUGH MOST OF N LOWER, THEN AFTER MIDNIGHT, THE RAIN MOVES INTO NE LOWER AND E UPPER. HOWEVER, THERE IS ENOUGH INSTABILITY AND DYNAMICS IN THE 500 MB JET (THE DIFLUENT AXIS OF THE JET RUNS THROUGH MICHIGAN). THERE WILL BE AT THE LEAST HIGH CHANCE POPS IN MOST OF THE STATE. THE CHANCES FOR SEVERE WEATHER WILL BE MOSTLY OVERNIGHT AS THE BEST BOUNDARY LAYER CAPE (AN APPROXIMATION FOR MIXED LAYER CAPE), LI, SI, AND 700-500 MB LAPSE RATES ARE OVERNIGHT INTO SATURDAY MORNING. THE ONLY THING TO WORRY ABOUT IS THE DEVELOPING DRY SLOT AS THE LOW STACKS UP IN WISCONSIN/W UPPER AROUND 18Z. WHICH WITH THE BULK SHEAR BEGIN GET INTO THE LOWER 40 KT RANGE AGAIN. SATURDAY NIGHT...WITH THE 500 MB LOW BEGINNING TO MEANDER OVER THE REGION, WOULD EXPECT THAT THE SFC BASED COMPONENT WITH THE CLOUDS AND THE LOSS OF SOLAR RADIATION. SO HAVE A CHANCE FOR RAIN AS THE SHOWERS UNDER THE LOW WILL TEND TO BE HIT AND MISS TO AN EXTENT. ALSO BY 12Z BOTH MODELS ARE BRINGING IN THE COLDER AIR AS THE 850 TEMPERATURES FALL BELOW 10C. SUNDAY...WITH THE MID LEVEL LAPSE RATES STEEPENING TO AROUND 7C/KM, WITH THE 500 MB LOW OVER US, WILL ALLOW FOR SHOWERS AND THUNDERSTORMS TO BECOME LIKELY. SUNDAY NIGHT...THE 500 MB LOW, WHICH IS FILLING, MOVES THROUGH SO WILL CONTINUE RAIN SHOWERS AND THUNDERSTORMS. EXTENDED (MONDAY THRU THURSDAY)...MONDAY, WITH THE LOW TO THE EAST OF THE REGION, THERE WILL BE RAIN SHOWERS, PROBABLY IN THE MORNING, AND THEN CLEAR OUT BY THE AFTERNOON, BUT IT BEING 4 DAYS OUT, WON`T GET CUTE. TUESDAY, THE 500 MB RIDGE AXIS IS EAST OF THE REGION AND SF HIGH PRESSURE IS BUILDING INTO THE REGION. SO DRY THROUGH THE DAY AND INTO THE EVENING. OVERNIGHT THE SHOWERS AND THUNDERSTORMS WILL PROBABLY MOVE INTO E UPPER AS THE COLD FRONT APPROACHES. WEDNESDAY, AS A LOW TRACKS INTO JAMES BAY, THE COLD FRONT DESCENDS AND BRINGS A CHANCE OF THUNDERSTORMS. THURSDAY, THE FRONT MOVES THROUGH THE REGION SO MORE FOR THE CHANCE OF THUNDERSTORMS. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 215 PM EDT THU JUN 26 2008 UPDATED AVIATION SECTION FOR 18Z TAFS .UPDATE... DUE TO LAST NIGHTS RAIN/LIGHT WINDS/50S DEWPOINTS...WIDESPREAD FOG DEVELOPED OVER LAKE SUPERIOR AND ADJACENT AREAS OF NORTHERN UPR MI LATE LAST NIGHT. NW/N WINDS OVR LK SUPERIOR AND IN AREAS EAST OF KEWEENAW PENINSULA TO WHITEFISH POINT WILL KEEP SOME FOG AND LOW CLOUDS INTO EARLY AFTN...AT LEAST ALONG THE IMMEDIATE SHORE. FOG OVR KEWEENAW IS ALREADY LIFTING...DUE TO WEAK ADVECTION OF DRY AIR HANGING OUT OVR WESTERN LAKE SUPERIOR. ONSHORE FLOW/CLOUDS/FOG SHOULD KEEP TEMPS IN THE UPR 50S TO UPR 60S ALONG LAKE SUPERIOR SHORE EAST OF THE KEWEENAW PENINSULA. MAINLY SUNNY SKIES INLAND AND STILL WARM H85/H8 TEMPS LEAD TO MAX TEMPS REACHING WELL INTO THE 80S OVR SCNTRL SECTIONS AWAY FM BAY OF GREEN BAY. MODIFIED GRB SOUNDING FOR T/TD OF 85/63 AND THAT DID GIVE SBCAPE AOA 1000 J/KG. HOWEVER ...DRY MID LEVEL AIR IS EVIDENT AS IS SOME CAPPING AROUND 750MB AND LARGE SCALE FORCING FOR ANY SHOWERS IS NIL. ABOUT THE ONLY TRIGGER WOULD BE LAKE BREEZE FRONT OFF LAKE MICHIGAN...BUT THAT WOULD APPEAR TO BE PRETTY SHALLOW AND NOT SUFFICIENT TO KICK OFF ANY CONVECTION. && .DISCUSSION (530 AM EDT)... MAIN CONCERNS FOCUS ON TIMING OF CONVECTION ON FRIDAY AND POSSIBLE SVR STORMS...THEN LINGERING SHRA/TSRA INTO THE WEEKEND. WATER VAPOR LOOP AND RUC ANALYSIS CONTINUE TO SHOW ZONAL FLOW ACROSS THE NRN CONUS. SHORTWAVE RESPONSIBLE FOR LAST NIGHT`S CONVECTION HAS MOVED EAST OF THE AREA. IR SATELLITE NOW SHOWS CLEARING SKIES FROM THE WEST AS MID LVL RDGG AND SUBSIDENCE NOSE INTO THE AREA. HOWEVER...DEWPOINTS REMAIN FAIRLY HIGH (UPR 50S TO LOW 60S) AND FOG LINGERS OVER MUCH OF LAKE SUPERIOR EARLY THIS MORNING AND OVER THE SHORELINE AREAS. TODAY...EXPECT AREAS OF FOG NEAR THE LAKE SUPERIOR SHORELINE TO LIFT AFTER SUNRISE WITH SUNNY SKIES PREVAILING UNDER MID-LVL RIDGING AND SUBSIDENCE. 800 MB TEMPS NEAR 12C MIXING TO THE SFC SHOULD YIELD HIGHS IN THE LOWER 80S OVER THE WRN INTERIOR. LAKE BREEZES DEVELOPING WILL KEEP TEMPS COOLER (LOWER 70S) NEAR THE GREAT LAKES AND OVER THE ERN FCST AREA. TONIGHT...EXPECT DRY CONDITIONS TO CONTINUE UNDER THE INFLUENCE OF THE SFC HIGH ALTHOUGH THERE WILL BE SOME INCREASE IN WAA MID-HIGH LVL CLOUDS FROM THE SW LATE AHEAD OF NEXT INCOMING SHORTWAVE. EXPECT LOWS TO GENERALLY BE IN THE MID 50S WITH SLIGHTLY COOLER READINGS EAST WHERE SKIES SHOULD BE CLEAR MOST OF THE NIGHT. FRIDAY...GENERALLY FOLLOWED A BLEND OF THE NAM/UKMET/ECMWF AND SREF MODELS AS THE GFS AND EVEN THE GLOBAL GEM LOOK TO BE AFFECTED BY CONVECTIVE FEEDBACK. ALL THESE MODELS BRING THE LEAD SHORTWAVE INTO THE AREA ON FRI AHEAD OF AN UPR TROF/CLOSED LOW DEVELOPING OVER THE NRN PLAINS. 305K ISENTROPIC ASCENT ASSOC WITH THIS SHORTWAVE WILL SUPPORT THE INITIAL BATCH OF CONVECTION SPREADING SW TO NE ACROSS THE FCST AREA...MAINLY LATE FRI. BUMPED UP POPS TO LIKELY ACROSS WEST AND CENTRAL PORTIONS SINCE MODELS HAVE COME INTO BETTER AGREEMENT ON TIMING/COVERAGE OF SHRA/TSRA. STRONG MOISTURE INFLOW WITH PWAT INCREASING TO AOA 1.5 INCHES COULD SUPPORT HEAVY DOWNPOURS WITH THE SHOWERS. MUCAPE VALUES INTO THE 1000-1500 J/KG RANGE AND 0-6KM BULK SHEAR INTO THE 30-40 KT RANGE WILL BE ENOUGH TO SUPPORT SOME STRONGER STORMS. HOWEVER...HIGH FREEZING LEVELS (13-14 KFT) SHOULD LIMIT LARGE HAIL THREAT. SPC STILL HAS THE ENTIRE U.P IN A SLIGHT RISK OF SVR FOR THE DAY2 CONVECTIVE OUTLOOK. FRI NIGHT...AS THE MID/UPPER LEVEL LOW SINKS SLOWLY ESE TOWARD THE UPPER GREAT LAKES...A DRY SLOT WILL SPREAD THROUGH THE AREA REDUCING PCPN CHANCES. FOLLOWED THE PREFERRED SLOWER TIMING OF THE ECMWF AND SREF WITH THIS FEATURE SO KEPT IN SHRA/TSRA CHANCES WITH THE HIGHEST POPS OVER THE EASTERN FCST AREA. SAT INTO SUN...FOLLOWED THE NCEP PREFERRED GFS ENSEMBLE MEAN SOLN WITH MVMT OF THE UPR LOW WHICH IS SIMILAR TO THE OPERATIONAL 00Z ECMWF RUN. FCST 500 MB TEMPS OF -17C/-18C WITH STEEP LOW-MID LEVEL LAPSE RATES AND FORCING FROM SHORTWAVES ROTATING AROUND THE LOW WILL SUPPORT SCT SHRA/TSRA THROUGH THE PERIOD. BY SUN...WITH NRLY LOW LEVEL FLOW DEVELOPING...MUCH COOLER WEATHER IS EXPECTED ESPECIALLY ALONG LAKE SUPERIOR. THERE WILL BE CONTINUED CHCS FOR LIGHT RAIN OR SHOWERS BUT TSTM SHOULD CHANCES SHOULD BE DWINDLING. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... W WINDS BRINGING IN STABLE AIR/CLEAR SKIES AT CMX SHOULD LAST INTO THIS EVENING. LOW PROBABILITY OF FOG THROUGH THE NIGHT AS THERE IS SOME WIND AND BKN MID-HIGH CLOUDS. ON FRI MORNING AT CMX...SE/E WINDS DEVELOP AS LOW PRESSURE MOVES INTO CNTRL MN. WIND DIRECTION AND FOG OUT OVR LAKE SUPERIOR MAY RESULT IN FOG OR LOW STRATUS RETURNING TO THE AIRPORT. VFR CONDITIONS EXPECTED AT SAW THROUGH THIS EVENING...THEN SINCE THERE IS STILL LINGERING LOW LEVEL MOISTURE FROM RECENT RAINS...MAY SEE RADIATION FOG LATE TONIGHT AT SAW. ENOUGH WIND JUST OFF SFC SHOULD KEEP VSBY FM FALLING TOO MUCH. SCT-BKN CU/SC EXPECTED ON FRI AT SAW AS WARMER AIR ALOFT LIFTS TOWARD UPPER MICHIGAN. ANY SHOWERS AND THUNDERSTORMS WILL HOLD OFF TIL LATE FRI AFTN. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... AS HIGH PRESSURE CROSSES LAKE SUPERIOR TODAY THROUGH FRIDAY MORNING WINDS WILL LESS THAN 20 KNOTS. ANOTHER LOW PRESSURE TROUGH WILL MOVE FROM THE NORTHERN PLAINS TONIGHT AND INTO LAKE SUPERIOR ON FRIDAY NIGHT AND REMAIN THROUGH SATURDAY. PRESSURE GRADIENTS WILL TIGHTEN FOLLOWING THE LOW CAUSING WIND TO INCREASE TO 20 TO 25 KNOTS FOR A PERIOD OVER CENTRAL AND EAST EASTERN LAKE SUPERIOR. BY SUNDAY...THE LOW FILLING SLIGHTLY AND SLIDE SOUTHEASTWARD OVER LOWER MICHIGAN BY SUNDAY MORNING WILL CAUSE THE WINDS TO LESS AN 20 KNOTS FOR THE REMAINDER OF THE PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...JLA DISCUSSION...VOSS AVIATION...JLA MARINE...KF mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1115 AM EDT THU JUN 26 2008 .UPDATE... DUE TO LAST NIGHTS RAIN/LIGHT WINDS/50S DEWPOINTS...WIDESPREAD FOG DEVELOPED OVER LAKE SUPERIOR AND ADJACENT AREAS OF NORTHERN UPR MI LATE LAST NIGHT. NW/N WINDS OVR LK SUPERIOR AND IN AREAS EAST OF KEWEENAW PENINSULA TO WHITEFISH POINT WILL KEEP SOME FOG AND LOW CLOUDS INTO EARLY AFTN...AT LEAST ALONG THE IMMEDIATE SHORE. FOG OVR KEWEENAW IS ALREADY LIFTING...DUE TO WEAK ADVECTION OF DRY AIR HANGING OUT OVR WESTERN LAKE SUPERIOR. ONSHORE FLOW/CLOUDS/FOG SHOULD KEEP TEMPS IN THE UPR 50S TO UPR 60S ALONG LAKE SUPERIOR SHORE EAST OF THE KEWEENAW PENINSULA. MAINLY SUNNY SKIES INLAND AND STILL WARM H85/H8 TEMPS LEAD TO MAX TEMPS REACHING WELL INTO THE 80S OVR SCNTRL SECTIONS AWAY FM BAY OF GREEN BAY. MODIFIED GRB SOUNDING FOR T/TD OF 85/63 AND THAT DID GIVE SBCAPE AOA 1000 J/KG. HOWEVER ...DRY MID LEVEL AIR IS EVIDENT AS IS SOME CAPPING AROUND 750MB AND LARGE SCALE FORCING FOR ANY SHOWERS IS NIL. ABOUT THE ONLY TRIGGER WOULD BE LAKE BREEZE FRONT OFF LAKE MICHIGAN...BUT THAT WOULD APPEAR TO BE PRETTY SHALLOW AND NOT SUFFICIENT TO KICK OFF ANY CONVECTION. && .DISCUSSION (530 AM EDT)... MAIN CONCERNS FOCUS ON TIMING OF CONVECTION ON FRIDAY AND POSSIBLE SVR STORMS...THEN LINGERING SHRA/TSRA INTO THE WEEKEND. WATER VAPOR LOOP AND RUC ANALYSIS CONTINUE TO SHOW ZONAL FLOW ACROSS THE NRN CONUS. SHORTWAVE RESPONSIBLE FOR LAST NIGHT`S CONVECTION HAS MOVED EAST OF THE AREA. IR SATELLITE NOW SHOWS CLEARING SKIES FROM THE WEST AS MID LVL RDGG AND SUBSIDENCE NOSE INTO THE AREA. HOWEVER...DEWPOINTS REMAIN FAIRLY HIGH (UPR 50S TO LOW 60S) AND FOG LINGERS OVER MUCH OF LAKE SUPERIOR EARLY THIS MORNING AND OVER THE SHORELINE AREAS. TODAY...EXPECT AREAS OF FOG NEAR THE LAKE SUPERIOR SHORELINE TO LIFT AFTER SUNRISE WITH SUNNY SKIES PREVAILING UNDER MID-LVL RIDGING AND SUBSIDENCE. 800 MB TEMPS NEAR 12C MIXING TO THE SFC SHOULD YIELD HIGHS IN THE LOWER 80S OVER THE WRN INTERIOR. LAKE BREEZES DEVELOPING WILL KEEP TEMPS COOLER (LOWER 70S) NEAR THE GREAT LAKES AND OVER THE ERN FCST AREA. TONIGHT...EXPECT DRY CONDITIONS TO CONTINUE UNDER THE INFLUENCE OF THE SFC HIGH ALTHOUGH THERE WILL BE SOME INCREASE IN WAA MID-HIGH LVL CLOUDS FROM THE SW LATE AHEAD OF NEXT INCOMING SHORTWAVE. EXPECT LOWS TO GENERALLY BE IN THE MID 50S WITH SLIGHTLY COOLER READINGS EAST WHERE SKIES SHOULD BE CLEAR MOST OF THE NIGHT. FRIDAY...GENERALLY FOLLOWED A BLEND OF THE NAM/UKMET/ECMWF AND SREF MODELS AS THE GFS AND EVEN THE GLOBAL GEM LOOK TO BE AFFECTED BY CONVECTIVE FEEDBACK. ALL THESE MODELS BRING THE LEAD SHORTWAVE INTO THE AREA ON FRI AHEAD OF AN UPR TROF/CLOSED LOW DEVELOPING OVER THE NRN PLAINS. 305K ISENTROPIC ASCENT ASSOC WITH THIS SHORTWAVE WILL SUPPORT THE INITIAL BATCH OF CONVECTION SPREADING SW TO NE ACROSS THE FCST AREA...MAINLY LATE FRI. BUMPED UP POPS TO LIKELY ACROSS WEST AND CENTRAL PORTIONS SINCE MODELS HAVE COME INTO BETTER AGREEMENT ON TIMING/COVERAGE OF SHRA/TSRA. STRONG MOISTURE INFLOW WITH PWAT INCREASING TO AOA 1.5 INCHES COULD SUPPORT HEAVY DOWNPOURS WITH THE SHOWERS. MUCAPE VALUES INTO THE 1000-1500 J/KG RANGE AND 0-6KM BULK SHEAR INTO THE 30-40 KT RANGE WILL BE ENOUGH TO SUPPORT SOME STRONGER STORMS. HOWEVER...HIGH FREEZING LEVELS (13-14 KFT) SHOULD LIMIT LARGE HAIL THREAT. SPC STILL HAS THE ENTIRE U.P IN A SLIGHT RISK OF SVR FOR THE DAY2 CONVECTIVE OUTLOOK. FRI NIGHT...AS THE MID/UPPER LEVEL LOW SINKS SLOWLY ESE TOWARD THE UPPER GREAT LAKES...A DRY SLOT WILL SPREAD THROUGH THE AREA REDUCING PCPN CHANCES. FOLLOWED THE PREFERRED SLOWER TIMING OF THE ECMWF AND SREF WITH THIS FEATURE SO KEPT IN SHRA/TSRA CHANCES WITH THE HIGHEST POPS OVER THE EASTERN FCST AREA. SAT INTO SUN...FOLLOWED THE NCEP PREFERRED GFS ENSEMBLE MEAN SOLN WITH MVMT OF THE UPR LOW WHICH IS SIMILAR TO THE OPERATIONAL 00Z ECMWF RUN. FCST 500 MB TEMPS OF -17C/-18C WITH STEEP LOW-MID LEVEL LAPSE RATES AND FORCING FROM SHORTWAVES ROTATING AROUND THE LOW WILL SUPPORT SCT SHRA/TSRA THROUGH THE PERIOD. BY SUN...WITH NRLY LOW LEVEL FLOW DEVELOPING...MUCH COOLER WEATHER IS EXPECTED ESPECIALLY ALONG LAKE SUPERIOR. THERE WILL BE CONTINUED CHCS FOR LIGHT RAIN OR SHOWERS BUT TSTM SHOULD CHANCES SHOULD BE DWINDLING. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... IR SATELLITE IMAGERY AND WEB CAMS INDICATED FAIRLY EXTENSIVE FOG OVER WRN LAKE SUPERIOR EXTENDING INTO THE KEWEENAW PENINSULA. UPSLOPING WEST NORTHWEST WINDS WILL KEEP LIFR CONDITIONS IN FOG/STRATUS APPEAR LIKELY THERE UNTIL AROUND 15Z...WHEN CONDITIONS SHOULD IMPROVE TO VFR. VFR CONDITIONS WILL THEN PREVAIL FOR THE REST OF THE FCST PERIOD. AT KSAW...VFR CONDITIONS WILL PREVAIL THROUGH THE FORECAST PERIOD. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... AS HIGH PRESSURE CROSSES LAKE SUPERIOR TODAY THROUGH FRIDAY MORNING WINDS WILL LESS THAN 20 KNOTS. ANOTHER LOW PRESSURE TROUGH WILL MOVE FROM THE NORTHERN PLAINS TONIGHT AND INTO LAKE SUPERIOR ON FRIDAY NIGHT AND REMAIN THROUGH SATURDAY. PRESSURE GRADIENTS WILL TIGHTEN FOLLOWING THE LOW CAUSING WIND TO INCREASE TO 20 TO 25 KNOTS FOR A PERIOD OVER CENTRAL AND EAST EASTERN LAKE SUPERIOR. BY SUNDAY...THE LOW FILLING SLIGHTLY AND SLIDE SOUTHEASTWARD OVER LOWER MICHIGAN BY SUNDAY MORNING WILL CAUSE THE WINDS TO LESS AN 20 KNOTS FOR THE REMAINDER OF THE PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...JLA DISCUSSION...VOSS AVIATION...ROLFSON/DLG MARINE...KF mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 731 AM EDT THU JUN 26 2008 .DISCUSSION... MAIN CONCERNS FOCUS ON TIMING OF CONVECTION ON FRIDAY AND POSSIBLE SVR STORMS...THEN LINGERING SHRA/TSRA INTO THE WEEKEND. WATER VAPOR LOOP AND RUC ANALYSIS CONTINUE TO SHOW ZONAL FLOW ACROSS THE NRN CONUS. SHORTWAVE RESPONSIBLE FOR LAST NIGHT`S CONVECTION HAS MOVED EAST OF THE AREA. IR SATELLITE NOW SHOWS CLEARING SKIES FROM THE WEST AS MID LVL RDGG AND SUBSIDENCE NOSE INTO THE AREA. HOWEVER...DEWPOINTS REMAIN FAIRLY HIGH (UPR 50S TO LOW 60S) AND FOG LINGERS OVER MUCH OF LAKE SUPERIOR EARLY THIS MORNING AND OVER THE SHORELINE AREAS. TODAY...EXPECT AREAS OF FOG NEAR THE LAKE SUPERIOR SHORELINE TO LIFT AFTER SUNRISE WITH SUNNY SKIES PREVAILING UNDER MID-LVL RIDGING AND SUBSIDENCE. 800 MB TEMPS NEAR 12C MIXING TO THE SFC SHOULD YIELD HIGHS IN THE LOWER 80S OVER THE WRN INTERIOR. LAKE BREEZES DEVELOPING WILL KEEP TEMPS COOLER (LOWER 70S) NEAR THE GREAT LAKES AND OVER THE ERN FCST AREA. TONIGHT...EXPECT DRY CONDITIONS TO CONTINUE UNDER THE INFLUENCE OF THE SFC HIGH ALTHOUGH THERE WILL BE SOME INCREASE IN WAA MID-HIGH LVL CLOUDS FROM THE SW LATE AHEAD OF NEXT INCOMING SHORTWAVE. EXPECT LOWS TO GENERALLY BE IN THE MID 50S WITH SLIGHTLY COOLER READINGS EAST WHERE SKIES SHOULD BE CLEAR MOST OF THE NIGHT. FRIDAY...GENERALLY FOLLOWED A BLEND OF THE NAM/UKMET/ECMWF AND SREF MODELS AS THE GFS AND EVEN THE GLOBAL GEM LOOK TO BE AFFECTED BY CONVECTIVE FEEDBACK. ALL THESE MODELS BRING THE LEAD SHORTWAVE INTO THE AREA ON FRI AHEAD OF AN UPR TROF/CLOSED LOW DEVELOPING OVER THE NRN PLAINS. 305K ISENTROPIC ASCENT ASSOC WITH THIS SHORTWAVE WILL SUPPORT THE INITIAL BATCH OF CONVECTION SPREADING SW TO NE ACROSS THE FCST AREA...MAINLY LATE FRI. BUMPED UP POPS TO LIKELY ACROSS WEST AND CENTRAL PORTIONS SINCE MODELS HAVE COME INTO BETTER AGREEMENT ON TIMING/COVERAGE OF SHRA/TSRA. STRONG MOISTURE INFLOW WITH PWAT INCREASING TO AOA 1.5 INCHES COULD SUPPORT HEAVY DOWNPOURS WITH THE SHOWERS. MUCAPE VALUES INTO THE 1000-1500 J/KG RANGE AND 0-6KM BULK SHEAR INTO THE 30-40 KT RANGE WILL BE ENOUGH TO SUPPORT SOME STRONGER STORMS. HOWEVER...HIGH FREEZING LEVELS (13-14 KFT) SHOULD LIMIT LARGE HAIL THREAT. SPC STILL HAS THE ENTIRE U.P IN A SLIGHT RISK OF SVR FOR THE DAY2 CONVECTIVE OUTLOOK. FRI NIGHT...AS THE MID/UPPER LEVEL LOW SINKS SLOWLY ESE TOWARD THE UPPER GREAT LAKES...A DRY SLOT WILL SPREAD THROUGH THE AREA REDUCING PCPN CHANCES. FOLLOWED THE PREFERRED SLOWER TIMING OF THE ECMWF AND SREF WITH THIS FEATURE SO KEPT IN SHRA/TSRA CHANCES WITH THE HIGHEST POPS OVER THE EASTERN FCST AREA. SAT INTO SUN...FOLLOWED THE NCEP PREFERRED GFS ENSEMBLE MEAN SOLN WITH MVMT OF THE UPR LOW WHICH IS SIMILAR TO THE OPERATIONAL 00Z ECMWF RUN. FCST 500 MB TEMPS OF -17C/-18C WITH STEEP LOW-MID LEVEL LAPSE RATES AND FORCING FROM SHORTWAVES ROTATING AROUND THE LOW WILL SUPPORT SCT SHRA/TSRA THROUGH THE PERIOD. BY SUN...WITH NRLY LOW LEVEL FLOW DEVELOPING...MUCH COOLER WEATHER IS EXPECTED ESPECIALLY ALONG LAKE SUPERIOR. THERE WILL BE CONTINUED CHCS FOR LIGHT RAIN OR SHOWERS BUT TSTM SHOULD CHANCES SHOULD BE DWINDLING. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... IR SATELLITE IMAGERY AND WEB CAMS INDICATED FAIRLY EXTENSIVE FOG OVER WRN LAKE SUPERIOR EXTENDING INTO THE KEWEENAW PENINSULA. UPSLOPING WEST NORTHWEST WINDS WILL KEEP LIFR CONDITIONS IN FOG/STRATUS APPEAR LIKELY THERE UNTIL AROUND 15Z...WHEN CONDITIONS SHOULD IMPROVE TO VFR. VFR CONDITIONS WILL THEN PREVAIL FOR THE REST OF THE FCST PERIOD. AT KSAW...VFR CONDITIONS WILL PREVAIL THROUGH THE FORECAST PERIOD. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... AS HIGH PRESSURE CROSSES LAKE SUPERIOR TODAY THROUGH FRIDAY MORNING WINDS WILL LESS THAN 20 KNOTS. ANOTHER LOW PRESSURE TROUGH WILL MOVE FROM THE NORTHERN PLAINS TONIGHT AND INTO LAKE SUPERIOR ON FRIDAY NIGHT AND REMAIN THROUGH SATURDAY. PRESSURE GRADIENTS WILL TIGHTEN FOLLOWING THE LOW CAUSING WIND TO INCREASE TO 20 TO 25 KNOTS FOR A PERIOD OVER CENTRAL AND EAST EASTERN LAKE SUPERIOR. BY SUNDAY...THE LOW FILLING SLIGHTLY AND SLIDE SOUTHEASTWARD OVER LOWER MICHIGAN BY SUNDAY MORNING WILL CAUSE THE WINDS TO LESS AN 20 KNOTS FOR THE REMAINDER OF THE PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...VOSS AVIATION...ROLFSON/DLG MARINE...KF mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 140 AM EDT THU JUN 26 2008 .AVIATION...THUNDERSTORMS ACROSS THE U.P. ARE SLIDING ESE EARLY THIS MORNING BUT SHOULD CLEAR KAPN/KPLN GIVEN STRONG CAPPING IN PLACE SOUTH OF THE STRAITS. BIGGEST FOCUS IS ON VISBYS/CIGS WITH PSEUDO-WARM FRONT SLIPPING NORTH THRU 12Z IN ADVANCE OF APPROACHING SFC COOL FRONT. ALREADY SEEING EXPANDING STRATUS DECK ALONG THIS BOUNDARY...WITH KTVC/KAPN STANDING THE BEST SHOT AT SEEING AT LEAST A TEMPORARY IFR CEILING/VISBY CREEP IN THRU SUNRISE. WILL ALSO BE WATCHING EXPANSIVE LAKE STRATUS DECK RUNNING THE LONG AXIS OF LAKE MICHIGAN...WHICH MAY BRIEFLY BE PUSHED INLAND TOWARD KTVC/KPLN AS INCOMING COOL FRONT SHIFTS WINDS NORTHWESTERLY TOWARD SUNRISE. OTHERWISE...JUST SOME SCATTERED (PERHAPS BROKEN FOR A TIME) CU TO FIRE THRU THE AFTN AS THERMAL TROUGH SLIPS OVERHEAD (SIMILAR TO UPSTREAM CONDITIONS YESTERDAY) BEFORE LOW LEVEL DRYING WINS OUT BY LATE AFTERNOON. COULD ALSO SEE BRIEFLY GUSTY WINDS FOR A TIME 15-21Z GIVEN MODESTLY MIXED BOUNDARY LAYER...THOUGH OVERALL LACK OF LOW LEVEL FLOW MAY ALSO ALLOW LAKE BREEZES TO PENETRATE TOWARD KAPN/KTVC BY MID AFTN. MPC/LAWRENCE && .DISCUSSION... /ISSUED 1010 PM EDT WED JUN 25 2008/ UPDATE...LATEST RUC ANALYSIS AND IR/WV/RADAR IMAGERY SHOW A WEAK SURFACE LOW TRANSVERSING OVER WESTERN LAKE SUPERIOR WITH WARM FRONT EXTENDING JUST NORTH OF THE LAKE SUPERIOR SHORELINE. SHOWERS AND THUNDERSTORMS...ALL SUB-SEVERE...CONTINUE TO DEVELOP JUST SOUTH OF THE SURFACE LOW WITHIN THE WARM SECTOR WITH SOME HELP FROM ADDED CONVERGENCE AS A RESULT OF LAKE BREEZES. THESE SHOWERS AND STORMS HAVE BEEN DISSIPATING AS THEY HEAD TOWARDS EASTERN ALGER COUNTY WHERE LOWER THETAE AIR RESIDES. ADDITIONAL THUNDERSTORMS ALSO HAVE BEEN REDEVELOPING AHEAD OF THE PARENT SHORTWAVE OVER THE ARROWHEAD OF MINNESOTA. FARTHER SOUTH...WEAK COOL FRONT/SURFACE TROUGH...WHICH EXTENDS ACROSS WESTERN WISCONSIN...HAS BEEN DORMANT IN REGARDS TO IGNITING CONVECTION DUE TO CAPPING ISSUES JUDGING BY 00Z GRB SOUNDING AS WARMING AIR SURGES NE AHEAD OF THE TROUGH. CLOSER TO HOME...A ROGUE SHOWER DEVELOPED OVER NE LOWER THIS EVENING BUT QUICKLY DISSIPATED LEAVING MOSTLY CLEAR TO PARTLY CLOUDY SKIES OVER MOST LOCALES. FOR THE REST OF THE NIGHT...THE WEAK SURFACE LOW WILL CONTINUE ITS TREK EAST AS HIGHER LOW LEVEL THETAE AIR WILL SURGE INTO THE REGION AHEAD OF ITS SURFACE TROUGH. STRONGEST (ALBEIT PRETTY MODEST) 700-500MB QG FORCING WILL RESIDE ACROSS EASTERN UPPER CLOSEST TO THE SHORTWAVE WITH A LITTLE 850-700MB -DIVQ CLIPPING NORTHERN LOWER TOWARDS THE TIP OF THE MITT. WITHIN THE THETAE AXIS...18Z NAM SHOWS 300-600 J/KG OF ELEVATED CAPE DEVELOPING BETWEEN 03-06Z...BUT CURRENT CONVECTION ACROSS THE U.P. APPEARS SURFACE BASED AND SHOULD DIMINISH SOMEWHAT AS DIURNAL INSTABILITY WANES. THE NAM ALSO TRIES TO DEVELOP A MODEST 25-30KT LLJ THAT POKES INTO EASTERN UPPER AFTER 03Z THAT CAN BOOST CONVERGENCE IN ADDITION TO THE CYCLONIC FLOW AROUND THE SURFACE LOW. THIS SEEMS TO POINT TOWARDS THE CONVECTION SURVIVING THE MARCH AS IT REACHES WHITEFISH POINT TO THE SOO LATER TONIGHT AND WILL BUMP UP POPS TO LIKELY. OVER NORTHERN LOWER...ABSENCE OF CONVECTION ALONG THE TROUGH THIS AFTERNOON MAKES ME THINK CAPPING WILL CONTINUE TO BE A PROBLEM FOR STORMS TO DEVELOP DESPITE AMPLE INSTABILITY ABOVE THE CAP. LACK OF UPPER LEVEL SUPPORT...AND WEAKENING SURFACE CONVERGENCE ALONG THE TROUGH DOES NOT HELP EITHER. HOWEVER...STILL A LITTLE WARY OF REMOVING PRECIP ALTOGETHER GIVEN ELEVATED INCOMING THETAE BOOST. SO WILL HEDGE AND GO ISOLATED THUNDER FOR NORTHERN LOWER OVERNIGHT. MPC && .PREV DISCUSSION... /ISSUED 329 PM EDT WED JUN 25 2008/ MID AFTERNOON OBSERVATIONAL AND NUMERICAL GUIDANCE ANALYSIS SHOWS PAIR OF EARLIER CONVECTIVELY INDUCED VORT LOBES...ONE OVER SOUTHERN LAKE MICHIGAN WITH THE OTHER OVER NORTH CENTRAL WISCONSIN...MAKING THEIR WAY EAST IN BROAD ZONAL WEST FLOW THAT LIES ACROSS THE NORTHERN CONUS AND SOUTHERN CANADA. AS FEARED...DESPITE SOMEWHAT INCREASING SUPPORT...AFTERNOON MIXING AND PRESENCE OF MID LEVEL CAP PREVENTING ANY SHOWER ACTIVITY OVER NORTHERN MICHIGAN (BESIDES SOME REMNANT SPRINKLES MAKING THEIR WAY ACROSS GLADWIN AND ARENAC COUNTIES FROM EARLIER DOWNSTATE CONVECTION). OTHERWISE... PLENTY OF SUNSHINE AND LIGHT SOUTHWEST FLOW ON BACKSIDE OF DEPARTING SURFACE RIDGE AXIS HAS LEAD TO A RATHER WARM SUMMER DAY...WITH AFTERNOON READINGS WELL INTO THE 70S AND LOWER 80S. FARTHER UPSTREAM...POTENTIAL NEXT WEATHER MAKER OF INTEREST IS NORTHERN MINNESOTA LOW AMPLITUDE SHORTWAVE AND ATTENDANT LOW PRESSURE/COLD FRONT MAKING STEADY EAST PROGRESS. FORECAST CONCERNS TONIGHT AND THURSDAY CENTER ON CONVECTIVE POTENTIAL AS THIS COLD FRONT PIVOTS SOUTHEAST ACROSS THE AREA. TONIGHT...THINKING THAT ANY LATE AFTERNOON ISOLATED SHOWERS AND STORMS THAT MANAGE TO DEVELOP WILL QUICKLY BE ON THE WANE...WITH ALL ATTENTION THEN TURNING TO UPSTREAM APPROACHING COLD FRONT. EXPECT CONVECTION TO QUICKLY FIRE THIS AFTERNOON ACROSS WESTERN UPPER MICHIGAN AND NORTH CENTRAL WISCONSIN AS CONVERGENCE AXIS WORKS ON 1500+ J/KG OF SURFACE BASED CAPE. SHOWERS AND STORMS WILL WORK EAST THIS EVENING FOLLOWING MOISTURE AXIS...PUSHING INTO EASTERN UPPER MICHIGAN LATER THIS EVENING. AFTER THAT...SEVERAL QUESTIONS ARISE AS OVERALL CONVERGENCE AND INSTABILITY WEAKENS AHEAD OF FRONTAL SYSTEM. THUS...FEEL COVERAGE AND INTENSITY OF SHOWERS AND STORMS WILL FOLLOW SUITE AS THEY DROP SOUTHEAST. THEREFORE...WILL TAPER POPS FROM NORTH TO SOUTH OVERNIGHT...NOT BRINGING IN CHANCE WORDING TO OUR SOUTHEAST ZONES UNTIL AFTER 09Z. AS FOR SEVERE WEATHER...REGION REMAINS OUT OF LATEST SPC SLIGHT RISK WORDING...WHICH SEEMS SUPPORTED BY BETTER BULK SHEAR REMAINING NORTH OF THE AREA AND RELATIVELY HIGH FREEZING LEVELS (>13.0 KFT). STILL...THINKING THE STRONGEST STORMS WILL BE CAPABLE OF SOME SMALL HAILS AND BRIEF GUSTY WINDS...ESPECIALLY LATER THIS EVENING ACROSS EASTERN UPPER MICHIGAN. THURSDAY...COLD FRONT CONTINUES TO DROP SOUTHEAST DURING THE MORNING AS PARENT LOW PUSHES INTO QUEBEC. WHILE MODELS REMAIN DRY DURING THE MORNING...HATE TO RULE OUT AT LEAST AN ISOLATED SHOWER OR STORM BEFORE FRONTAL PASSAGE. EARLY AFTERNOON HOURS COULD GET QUITE INTERESTING OVER FAR SOUTHEAST SECTIONS OF THE AREA IF COLD FRONT STALLS FROM INTENSE MORNING WARMING. MODIFYING A NAM-WRF SOUNDING (IGNORING OVERZEALOUS LOW 70 DEWPOINTS) YIELDS 1500+ J/KG MEAN LAYER CAPE. WILL KEEP LOW POP MENTION FOR THIS POSSIBILITY THROUGH 21Z BEFORE FRONT SAGS FAR ENOUGH SOUTH TO SUPPRESS CONVECTION. OTHER STORY WILL BE RATHER WARM TEMPERATURES...WITH READINGS PUSHING THE UPPER 80S SOUTHEAST OF WEST BRANCH. FARTHER NORTH...MID 70S TO LOWER 80S ARE EXPECTED...WITH TEMPERATURES SEVERAL DEGREES COOLER ALONG THE LAKE MICHIGAN SHORELINE. MSB THURSDAY NIGHT THRU FRIDAY NIGHT...STILL EXPECT A DRY THURSDAY NIGHT WITH WEAK RIDGING...SUBSIDENCE AND DRY AIR OVERHEAD. CONVECTIVE ACTIVITY PICKS UP AGAIN ON FRIDAY AS MOISTURE AND INSTABILITY INCREASE ACROSS THE WRN GREAT LAKES ALONG AND AHEAD OF A WARM FRONT. THIS FRONT IS ASSOCIATED WITH AN UNSEASONABLY STRONG LOW PRESSURE SYSTEM APPROACHING THE WRN GREAT LAKES REGION (MORE ON THIS SYSTEM BELOW). BEST INSTABILITY AND 850 THETA-E ADVECTION WILL OCCUR WELL SW OF OUR CWA OVER KANSAS...MISSOURI AND ILLINOIS (AN AREA THAT CERTAINLY DOES NOT NEED MORE RAIN). EXPECT BEST CHANCE OF SVR TSRA WILL BE IN THIS AREA WHERE STRONGER WIND FIELDS AND BETTER WIND SHEAR EXIST. STILL...CANNOT RULE OUT AN ISOLD SVR STORM FRIDAY AFTERNOON AND NIGHT WITH MODEST WIND SHEAR...CAPES APPROACHING 1000 J/KG AND THE 850 MB THETA E RIDGE AXIS JUST UPSTREAM. WILL MAINTAIN CHANCE OF SHRA/TSRA FOR FRIDAY AND LIKELY POPS FOR FRIDAY NIGHT. LOW TEMPS WILL FALL INTO THE UPPER 50S/LOWER 60S BOTH THURSDAY NIGHT AND FRIDAY NIGHT. HIGH TEMPS WILL WARM INTO THE UPPER 70S/LOWER 80S FRIDAY AFTERNOON. SATURDAY THRU WEDNESDAY...IMPRESSIVE UPPER LOW WILL DIVE SE OUT OF S CENTRAL CANADA INTO NRN MICHIGAN ON SATURDAY. SURFACE REFLECTION BECOMES VERTICALLY STACKED WITH THE DEEP CLOSED 500 MB LOW... RESULTING IN A VERY SLOW EASTWARD PROGRESSION AWAY FROM THE STATE FOR SUNDAY INTO MONDAY. AS MENTIONED ABOVE...SYSTEM IS UNSEASONABLY STRONG AND VERY DYNAMIC. IN ADDITION...LATEST MODELS STILL SUGGEST MAIN AREA OF CONVECTION ALONG AND AHEAD OF THE LOW AND COLD FRONT WILL IMPACT OUR AREA DURING PEAK HEATING SATURDAY AFTERNOON/EVENING. HAVE BOOSTED POPS TO LIKELY FOR SATURDAY AS MICHIGAN FINDS ITSELF WITHIN THE INSTABILITY AND MOISTURE AXES AHEAD OF THE SYSTEM. HAVE ALSO INCREASED POPS TO LIKELY FOR SATURDAY NIGHT AND SUNDAY AS THE STACKED LOW MOVES THRU NRN MICHIGAN AND THEN STALLS OVER LAKE HURON. CHANCE POPS SHOULD REMAIN IN THE FORECAST THRU MONDAY AS AMPLE LOW LEVEL MOISTURE...GOOD CYCLONIC FLOW AND SUFFICIENT INSTABILITY REMAIN OVER THE AREA AS THE 500 MB COLD POOL ARRIVES. MONDAY NIGHT THRU WEDNESDAY STILL LOOKS DRY AS HIGH PRESSURE/RIDGING/DRIER AIR SETTLE INTO THE REGION. EXPECT HIGH TEMPS MAINLY IN THE 70S AND LOWS IN THE 50S THRU THE PERIOD. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1010 PM EDT WED JUN 25 2008 .UPDATE...LATEST RUC ANALYSIS AND IR/WV/RADAR IMAGERY SHOW A WEAK SURFACE LOW TRANSVERSING OVER WESTERN LAKE SUPERIOR WITH WARM FRONT EXTENDING JUST NORTH OF THE LAKE SUPERIOR SHORELINE. SHOWERS AND THUNDERSTORMS...ALL SUB-SEVERE...CONTINUE TO DEVELOP JUST SOUTH OF THE SURFACE LOW WITHIN THE WARM SECTOR WITH SOME HELP FROM ADDED CONVERGENCE AS A RESULT OF LAKE BREEZES. THESE SHOWERS AND STORMS HAVE BEEN DISSIPATING AS THEY HEAD TOWARDS EASTERN ALGER COUNTY WHERE LOWER THETAE AIR RESIDES. ADDITIONAL THUNDERSTORMS ALSO HAVE BEEN REDEVELOPING AHEAD OF THE PARENT SHORTWAVE OVER THE ARROWHEAD OF MINNESOTA. FARTHER SOUTH...WEAK COOL FRONT/SURFACE TROUGH...WHICH EXTENDS ACROSS WESTERN WISCONSIN...HAS BEEN DORMANT IN REGARDS TO IGNITING CONVECTION DUE TO CAPPING ISSUES JUDGING BY 00Z GRB SOUNDING AS WARMING AIR SURGES NE AHEAD OF THE TROUGH. CLOSER TO HOME...A ROGUE SHOWER DEVELOPED OVER NE LOWER THIS EVENING BUT QUICKLY DISSIPATED LEAVING MOSTLY CLEAR TO PARTLY CLOUDY SKIES OVER MOST LOCALES. FOR THE REST OF THE NIGHT...THE WEAK SURFACE LOW WILL CONTINUE ITS TREK EAST AS HIGHER LOW LEVEL THETAE AIR WILL SURGE INTO THE REGION AHEAD OF ITS SURFACE TROUGH. STRONGEST (ALBEIT PRETTY MODEST) 700-500MB QG FORCING WILL RESIDE ACROSS EASTERN UPPER CLOSEST TO THE SHORTWAVE WITH A LITTLE 850-700MB -DIVQ CLIPPING NORTHERN LOWER TOWARDS THE TIP OF THE MITT. WITHIN THE THETAE AXIS...18Z NAM SHOWS 300-600 J/KG OF ELEVATED CAPE DEVELOPING BETWEEN 03-06Z...BUT CURRENT CONVECTION ACROSS THE U.P. APPEARS SURFACE BASED AND SHOULD DIMINISH SOMEWHAT AS DIURNAL INSTABILITY WANES. THE NAM ALSO TRIES TO DEVELOP A MODEST 25-30KT LLJ THAT POKES INTO EASTERN UPPER AFTER 03Z THAT CAN BOOST CONVERGENCE IN ADDITION TO THE CYCLONIC FLOW AROUND THE SURFACE LOW. THIS SEEMS TO POINT TOWARDS THE CONVECTION SURVIVING THE MARCH AS IT REACHES WHITEFISH POINT TO THE SOO LATER TONIGHT AND WILL BUMP UP POPS TO LIKELY. OVER NORTHERN LOWER...ABSENCE OF CONVECTION ALONG THE TROUGH THIS AFTERNOON MAKES ME THINK CAPPING WILL CONTINUE TO BE A PROBLEM FOR STORMS TO DEVELOP DESPITE AMPLE INSTABILITY ABOVE THE CAP. LACK OF UPPER LEVEL SUPPORT...AND WEAKENING SURFACE CONVERGENCE ALONG THE TROUGH DOES NOT HELP EITHER. HOWEVER...STILL A LITTLE WARY OF REMOVING PRECIP ALTOGETHER GIVEN ELEVATED INCOMING THETAE BOOST. SO WILL HEDGE AND GO ISOLATED THUNDER FOR NORTHERN LOWER OVERNIGHT. MPC && .PREV DISCUSSION... /ISSUED 707 PM EDT WED JUN 25 2008/ AVIATION...ANOTHER CHALLENGING FORECAST IN THE AVIATION DEPARTMENT TONIGHT. WEAK AREA OF LOW PRESSURE WILL TRACK ALONG A LOW LEVEL BOUNDARY OVER LAKE SUPERIOR WHILE DRAGGING A SURFACE TROUGH ACROSS THE REGION LATE TONIGHT INTO TOMORROW MORNING. NARROW CORRIDOR OF A JUICIER AIRMASS WILL MOVE IN AHEAD OF THE TROUGH...WHICH WILL PROVIDE SOME INSTABILITY FOR SHOWER AND THUNDERSTORM DEVELOPMENT. HOW MUCH LIFT IS THE KEY QUESTION WHETHER THE TAF SITES WILL REMAIN DRY. FEEL BETTER CHANCES WILL REMAIN ACROSS EASTERN UPPER...AND A SHOWER COULD SNEAK INTO PLN AFTER MIDNIGHT. HOWEVER...BELIEVE LIFT WILL BE TOO WEAK FOR PRECIP AT TVC/APN. SO WILL MAINTAIN SCT LOW LEVEL CLOUDS AHEAD OF THE TROUGH. ONCE THE TROUGH EXITS BY AFTERNOON...DRIER AIR WILL LIKELY ERODE ANY CUMULUS CLOUDS THAT POP UP AT ALL TAF SITES EXCEPT APN WHERE A POTENTIAL LAKE BREEZE MAY KEEP A FEW CLOUDS AROUND. MPC PREV DISCUSSION... /ISSUED 329 PM EDT WED JUN 25 2008/ DISCUSSION...MID AFTERNOON OBSERVATIONAL AND NUMERICAL GUIDANCE ANALYSIS SHOWS PAIR OF EARLIER CONVECTIVELY INDUCED VORT LOBES...ONE OVER SOUTHERN LAKE MICHIGAN WITH THE OTHER OVER NORTH CENTRAL WISCONSIN...MAKING THEIR WAY EAST IN BROAD ZONAL WEST FLOW THAT LIES ACROSS THE NORTHERN CONUS AND SOUTHERN CANADA. AS FEARED...DESPITE SOMEWHAT INCREASING SUPPORT...AFTERNOON MIXING AND PRESENCE OF MID LEVEL CAP PREVENTING ANY SHOWER ACTIVITY OVER NORTHERN MICHIGAN (BESIDES SOME REMNANT SPRINKLES MAKING THEIR WAY ACROSS GLADWIN AND ARENAC COUNTIES FROM EARLIER DOWNSTATE CONVECTION). OTHERWISE... PLENTY OF SUNSHINE AND LIGHT SOUTHWEST FLOW ON BACKSIDE OF DEPARTING SURFACE RIDGE AXIS HAS LEAD TO A RATHER WARM SUMMER DAY...WITH AFTERNOON READINGS WELL INTO THE 70S AND LOWER 80S. FARTHER UPSTREAM...POTENTIAL NEXT WEATHER MAKER OF INTEREST IS NORTHERN MINNESOTA LOW AMPLITUDE SHORTWAVE AND ATTENDANT LOW PRESSURE/COLD FRONT MAKING STEADY EAST PROGRESS. FORECAST CONCERNS TONIGHT AND THURSDAY CENTER ON CONVECTIVE POTENTIAL AS THIS COLD FRONT PIVOTS SOUTHEAST ACROSS THE AREA. TONIGHT...THINKING THAT ANY LATE AFTERNOON ISOLATED SHOWERS AND STORMS THAT MANAGE TO DEVELOP WILL QUICKLY BE ON THE WANE...WITH ALL ATTENTION THEN TURNING TO UPSTREAM APPROACHING COLD FRONT. EXPECT CONVECTION TO QUICKLY FIRE THIS AFTERNOON ACROSS WESTERN UPPER MICHIGAN AND NORTH CENTRAL WISCONSIN AS CONVERGENCE AXIS WORKS ON 1500+ J/KG OF SURFACE BASED CAPE. SHOWERS AND STORMS WILL WORK EAST THIS EVENING FOLLOWING MOISTURE AXIS...PUSHING INTO EASTERN UPPER MICHIGAN LATER THIS EVENING. AFTER THAT...SEVERAL QUESTIONS ARISE AS OVERALL CONVERGENCE AND INSTABILITY WEAKENS AHEAD OF FRONTAL SYSTEM. THUS...FEEL COVERAGE AND INTENSITY OF SHOWERS AND STORMS WILL FOLLOW SUITE AS THEY DROP SOUTHEAST. THEREFORE...WILL TAPER POPS FROM NORTH TO SOUTH OVERNIGHT...NOT BRINGING IN CHANCE WORDING TO OUR SOUTHEAST ZONES UNTIL AFTER 09Z. AS FOR SEVERE WEATHER...REGION REMAINS OUT OF LATEST SPC SLIGHT RISK WORDING...WHICH SEEMS SUPPORTED BY BETTER BULK SHEAR REMAINING NORTH OF THE AREA AND RELATIVELY HIGH FREEZING LEVELS (>13.0 KFT). STILL...THINKING THE STRONGEST STORMS WILL BE CAPABLE OF SOME SMALL HAILS AND BRIEF GUSTY WINDS...ESPECIALLY LATER THIS EVENING ACROSS EASTERN UPPER MICHIGAN. THURSDAY...COLD FRONT CONTINUES TO DROP SOUTHEAST DURING THE MORNING AS PARENT LOW PUSHES INTO QUEBEC. WHILE MODELS REMAIN DRY DURING THE MORNING...HATE TO RULE OUT AT LEAST AN ISOLATED SHOWER OR STORM BEFORE FRONTAL PASSAGE. EARLY AFTERNOON HOURS COULD GET QUITE INTERESTING OVER FAR SOUTHEAST SECTIONS OF THE AREA IF COLD FRONT STALLS FROM INTENSE MORNING WARMING. MODIFYING A NAM-WRF SOUNDING (IGNORING OVERZEALOUS LOW 70 DEWPOINTS) YIELDS 1500+ J/KG MEAN LAYER CAPE. WILL KEEP LOW POP MENTION FOR THIS POSSIBILITY THROUGH 21Z BEFORE FRONT SAGS FAR ENOUGH SOUTH TO SUPPRESS CONVECTION. OTHER STORY WILL BE RATHER WARM TEMPERATURES...WITH READINGS PUSHING THE UPPER 80S SOUTHEAST OF WEST BRANCH. FARTHER NORTH...MID 70S TO LOWER 80S ARE EXPECTED...WITH TEMPERATURES SEVERAL DEGREES COOLER ALONG THE LAKE MICHIGAN SHORELINE. MSB THURSDAY NIGHT THRU FRIDAY NIGHT...STILL EXPECT A DRY THURSDAY NIGHT WITH WEAK RIDGING...SUBSIDENCE AND DRY AIR OVERHEAD. CONVECTIVE ACTIVITY PICKS UP AGAIN ON FRIDAY AS MOISTURE AND INSTABILITY INCREASE ACROSS THE WRN GREAT LAKES ALONG AND AHEAD OF A WARM FRONT. THIS FRONT IS ASSOCIATED WITH AN UNSEASONABLY STRONG LOW PRESSURE SYSTEM APPROACHING THE WRN GREAT LAKES REGION (MORE ON THIS SYSTEM BELOW). BEST INSTABILITY AND 850 THETA-E ADVECTION WILL OCCUR WELL SW OF OUR CWA OVER KANSAS...MISSOURI AND ILLINOIS (AN AREA THAT CERTAINLY DOES NOT NEED MORE RAIN). EXPECT BEST CHANCE OF SVR TSRA WILL BE IN THIS AREA WHERE STRONGER WIND FIELDS AND BETTER WIND SHEAR EXIST. STILL...CANNOT RULE OUT AN ISOLD SVR STORM FRIDAY AFTERNOON AND NIGHT WITH MODEST WIND SHEAR...CAPES APPROACHING 1000 J/KG AND THE 850 MB THETA E RIDGE AXIS JUST UPSTREAM. WILL MAINTAIN CHANCE OF SHRA/TSRA FOR FRIDAY AND LIKELY POPS FOR FRIDAY NIGHT. LOW TEMPS WILL FALL INTO THE UPPER 50S/LOWER 60S BOTH THURSDAY NIGHT AND FRIDAY NIGHT. HIGH TEMPS WILL WARM INTO THE UPPER 70S/LOWER 80S FRIDAY AFTERNOON. SATURDAY THRU WEDNESDAY...IMPRESSIVE UPPER LOW WILL DIVE SE OUT OF S CENTRAL CANADA INTO NRN MICHIGAN ON SATURDAY. SURFACE REFLECTION BECOMES VERTICALLY STACKED WITH THE DEEP CLOSED 500 MB LOW... RESULTING IN A VERY SLOW EASTWARD PROGRESSION AWAY FROM THE STATE FOR SUNDAY INTO MONDAY. AS MENTIONED ABOVE...SYSTEM IS UNSEASONABLY STRONG AND VERY DYNAMIC. IN ADDITION...LATEST MODELS STILL SUGGEST MAIN AREA OF CONVECTION ALONG AND AHEAD OF THE LOW AND COLD FRONT WILL IMPACT OUR AREA DURING PEAK HEATING SATURDAY AFTERNOON/EVENING. HAVE BOOSTED POPS TO LIKELY FOR SATURDAY AS MICHIGAN FINDS ITSELF WITHIN THE INSTABILITY AND MOISTURE AXES AHEAD OF THE SYSTEM. HAVE ALSO INCREASED POPS TO LIKELY FOR SATURDAY NIGHT AND SUNDAY AS THE STACKED LOW MOVES THRU NRN MICHIGAN AND THEN STALLS OVER LAKE HURON. CHANCE POPS SHOULD REMAIN IN THE FORECAST THRU MONDAY AS AMPLE LOW LEVEL MOISTURE...GOOD CYCLONIC FLOW AND SUFFICIENT INSTABILITY REMAIN OVER THE AREA AS THE 500 MB COLD POOL ARRIVES. MONDAY NIGHT THRU WEDNESDAY STILL LOOKS DRY AS HIGH PRESSURE/RIDGING/DRIER AIR SETTLE INTO THE REGION. EXPECT HIGH TEMPS MAINLY IN THE 70S AND LOWS IN THE 50S THRU THE PERIOD. AVIATION... /ISSUED 140 PM EDT WED JUN 25 2008/ BESIDES SOME SCATTERED CU AND CIRRUS...ANOTHER UNEVENTFUL DAY ACROSS ALL TAF SITES AS HIGH PRESSURE RIDGING REMAINS IN CONTROL. MORE OF THE SAME EXPECTED THROUGH THE EARLY EVENING BEFORE APPROACHING FRONTAL SYSTEM BRINGS THE THREAT OF SOME WIDELY SCATTERED SHOWERS AND STORMS. AT THIS TIME...MUCH UNCERTAINTY EXISTS REGARDING BOTH TIMING AND COVERAGE OF SHOWERS AND STORMS...SO HAVE SIMPLY LEFT ANY MENTION OUT OF TAFS. WIND SHIFT TO MORE WNW EXPECTED THURSDAY. MSB && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 142 AM EDT WED JUN 25 2008 UPDATED FOR 18Z TAF ISSUANCE .SYNOPSIS (ISSUED AT 557 AM EDT WED)... WV IMAGERY AND RUC ANALYSIS INDICATED A MAINLY ZONAL PATTERN ACROSS THE NRN CONUS WITH SEVERAL SHORTWAVE TROUGHS OF NOTE. ONE SHRTWV MOVING ACROSS LAKE SUPERIOR SUPPORTED A LINE OF ISOLD SHRA EARLY THIS MORNING STRETCHING WEST TO EAST ACROSS LAKE SUPERIOR ALONG A SFC TROF INTERSECTING THE KEWEENAW PENINSULA. ANOTHER SHORTWAVE OVER SRN MANITOBA WILL BE POISED TO MOVE ACROSS THE UPR GREAT LAKES THIS AFTERNOON AND EVENING BRINGING THE POTENTIAL FOR ISOLD TO SCT SHRA/TSRA. && .DISCUSSION... TODAY...THE SRN SASK SHRTWV WILL MOVE ACROSS THE AREA. MODELS SUGGEST GREATER INSTABILITY WILL DEVELOP AS LOW LEVEL MOISTURE ADVECTS TOWARD THE WRN LAKES FROM IA AND SRN MN. FCST TEMP/DEWPOINTS NEAR 80/60 WOULD INDICATE CAPE VALUES BETWEEN 500-1000 J/KG. IF THIS INSTABILITY IS REALIZED...THERE IS SUFFICIENT DEEP LAYER SHEAR OF 40-50KT TO LEAD TO A FEW ISOLD SVR STORMS. THE BIG QUESTION IS WILL DRIER (MID-UPR 50S) DEWPOINTS MIX TO THE SFC SIMILAR TO WHAT HAPPENED YESTERDAY AND LIMIT AND/OR INHIBIT CONVECTION. LOOKING AT HOW DRY UPSTREAM 00Z SNDGS AT KINL AND KMPX ARE...I CERTAINLY THINK THAT THE NAM AND GFS MODEL DEWPOINTS ARE OVERDONE. IF DRY AIR ALOFT DOES LOWER SFC DEWPOINTS INTO THE MID-UPR 50S...IT WILL HARD TO BREAK THROUGH MID LVL CAP AT 750 MB. SPC MUST ALSO BE THINKING ALONG LINES OF A REDUCED THREAT OR DRIER SOLN AS THEY HAVE DROPPED OUR CWA OUT OF SLIGHT RISK FOR DAY1. WILL FOLLOW SUIT ON THE HWO AND DROP RISK OF SVR TODAY...BUT WILL LEAVE IN MENTION OF STRONGER STORMS CONTAINING SMALL HAIL AND GUSTY WINDS TO 50 MPH. KEPT LOW CHC POPS GOING FOR THE AFTERNOON ACROSS MUCH OF THE CWA. WED NIGHT AND THU...WILL MAINTAIN LOW CHANCE POPS FOR ANY AFTERNOON CONVECTION THAT MAY LINGER INTO THE EVENING ON TAIL END OF DEPARTING SHORTWAVE...MAINLY FOR CENTRAL AND ERN SECTIONS OF THE CWA. OTHERWISE...EXPECT DRY CONDITIONS INTO THU AS DNVA/RIDGING MOVE IN BEHIND THE SHRTWV. 850MB TEMPS AROUND 14C WILL ALLOW LOCATIONS AWAY FROM THE GREAT LAKES TO CLIMB INTO THE LOW TO MID 80S. COOLER READINGS WILL OCCUR ALONG THE GREAT LAKES SHORELINES AS LAKE BREEZES DEVELOP UNDER WEAK GRADIENT FROM HIGH PRESSURE OVERHEAD. FRI...ANOTHER SHORTWAVE EMERGES FROM THE BRITISH COLUMBIA COAST AND CARVES OUT CLOSED LOW OVER THE HIGH PLAINS BY LATE FRI INTO FRIDAY NIGHT. KEPT HIGHEST POPS FRI AFTERNOON OVER THE WEST HALF AND SPREAD LIKELY POPS ACROSS THE AREA FRI NIGHT AS MODELS SHOW IMPRESSIVE HEIGHT FALLS AHEAD OF THE APPROACHING UPR LOW. SPC STILL INDICATES A SLIGHT RISK FOR SVR STORMS ACROSS MUCH OF OUR AREA FRI AFTERNOON INTO FRI NIGHT WHICH SEEMS REASONABLE GIVEN GFS FCST OF MLCAPES OF 500-1000 J/KG AND 30-40 KT 0-6KM BULK SHEAR. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... VFR CIGS AND VIS REMAIN DESPITE A DISTURBANCE/FRONTAL BOUNDARIES SWEEPING THROUGH THE AREA. MOST OF THE ACTIVITY REMAINS OVER LAKE SUPERIOR...WITH ONLY SHORT TOP CUMULUS POPPING UP OVER LAND THUS FAR. WENT WITH TEMPO SHOWERS AT CMX...WITH A BETTER CHANCE LATE THIS AFTERNOON AT SAW. THE CHANCE OF SHOWERS AND THUNDERSTORMS WILL GREATLY DECREASE ONCE AGAIN WITH THE LOSS OF DAYTIME HEATING AND THE EXITING DISTURBANCE AND THE WEAK COLD FRONT SLIDING EAST OF SAW BY 06Z. THE MAIN DIFFERENCE WITH BE A WESTERLY SHIFT TO THE WINDS AND FEWER CLOUDS FOR THURSDAY. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... WINDS/WAVES SHOULD REMAIN FAIRLY LIGHT ACROSS THE LAKE TODAY. THE GENERAL WEATHER PATTERN SUGGESTS WINDS WILL REMAIN SOUTHERLY THROUGH SATURDAY AS HIGH PRESSURE SHIFTS EAST OF LAKE SUPERIOR. SOME BRIEF SHIFTS OF WIND WILL OCCUR ON TODAY WITH ANY SHOWERS DEVELOPMENT...BUT WINDS SHOULD GENERALLY REMAIN 20 KNOTS OR LESS THROUGH REST OF THE PERIOD. AS THE NEXT LOW PASSES THROUGH THE AREA ON SUNDAY WINDS WILL VEER NORTH. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/DISCUSSION...VOSS AVIATION...KF MARINE...DLG mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 729 AM EDT WED JUN 25 2008 .SYNOPSIS... WV IMAGERY AND RUC ANALYSIS INDICATED A MAINLY ZONAL PATTERN ACROSS THE NRN CONUS WITH SEVERAL SHORTWAVE TROUGHS OF NOTE. ONE SHRTWV MOVING ACROSS LAKE SUPERIOR SUPPORTED A LINE OF ISOLD SHRA EARLY THIS MORNING STRETCHING WEST TO EAST ACROSS LAKE SUPERIOR ALONG A SFC TROF INTERSECTING THE KEWEENAW PENINSULA. ANOTHER SHORTWAVE OVER SRN MANITOBA WILL BE POISED TO MOVE ACROSS THE UPR GREAT LAKES THIS AFTERNOON AND EVENING BRINGING THE POTENTIAL FOR ISOLD TO SCT SHRA/TSRA. && .DISCUSSION... TODAY...THE SRN SASK SHRTWV WILL MOVE ACROSS THE AREA. MODELS SUGGEST GREATER INSTABILITY WILL DEVELOP AS LOW LEVEL MOISTURE ADVECTS TOWARD THE WRN LAKES FROM IA AND SRN MN. FCST TEMP/DEWPOINTS NEAR 80/60 WOULD INDICATE CAPE VALUES BETWEEN 500-1000 J/KG. IF THIS INSTABILITY IS REALIZED...THERE IS SUFFICIENT DEEP LAYER SHEAR OF 40-50KT TO LEAD TO A FEW ISOLD SVR STORMS. THE BIG QUESTION IS WILL DRIER (MID-UPR 50S) DEWPOINTS MIX TO THE SFC SIMILAR TO WHAT HAPPENED YESTERDAY AND LIMIT AND/OR INHIBIT CONVECTION. LOOKING AT HOW DRY UPSTREAM 00Z SNDGS AT KINL AND KMPX ARE...I CERTAINLY THINK THAT THE NAM AND GFS MODEL DEWPOINTS ARE OVERDONE. IF DRY AIR ALOFT DOES LOWER SFC DEWPOINTS INTO THE MID-UPR 50S...IT WILL HARD TO BREAK THROUGH MID LVL CAP AT 750 MB. SPC MUST ALSO BE THINKING ALONG LINES OF A REDUCED THREAT OR DRIER SOLN AS THEY HAVE DROPPED OUR CWA OUT OF SLIGHT RISK FOR DAY1. WILL FOLLOW SUIT ON THE HWO AND DROP RISK OF SVR TODAY...BUT WILL LEAVE IN MENTION OF STRONGER STORMS CONTAINING SMALL HAIL AND GUSTY WINDS TO 50 MPH. KEPT LOW CHC POPS GOING FOR THE AFTERNOON ACROSS MUCH OF THE CWA. WED NIGHT AND THU...WILL MAINTAIN LOW CHANCE POPS FOR ANY AFTERNOON CONVECTION THAT MAY LINGER INTO THE EVENING ON TAIL END OF DEPARTING SHORTWAVE...MAINLY FOR CENTRAL AND ERN SECTIONS OF THE CWA. OTHERWISE...EXPECT DRY CONDITIONS INTO THU AS DNVA/RIDGING MOVE IN BEHIND THE SHRTWV. 850MB TEMPS AROUND 14C WILL ALLOW LOCATIONS AWAY FROM THE GREAT LAKES TO CLIMB INTO THE LOW TO MID 80S. COOLER READINGS WILL OCCUR ALONG THE GREAT LAKES SHORELINES AS LAKE BREEZES DEVELOP UNDER WEAK GRADIENT FROM HIGH PRESSURE OVERHEAD. FRI...ANOTHER SHORTWAVE EMERGES FROM THE BRITISH COLUMBIA COAST AND CARVES OUT CLOSED LOW OVER THE HIGH PLAINS BY LATE FRI INTO FRIDAY NIGHT. KEPT HIGHEST POPS FRI AFTERNOON OVER THE WEST HALF AND SPREAD LIKELY POPS ACROSS THE AREA FRI NIGHT AS MODELS SHOW IMPRESSIVE HEIGHT FALLS AHEAD OF THE APPROACHING UPR LOW. SPC STILL INDICATES A SLIGHT RISK FOR SVR STORMS ACROSS MUCH OF OUR AREA FRI AFTERNOON INTO FRI NIGHT WHICH SEEMS REASONABLE GIVEN GFS FCST OF MLCAPES OF 500-1000 J/KG AND 30-40 KT 0-6KM BULK SHEAR. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... VFR CIGS AND VIS TO DOMINATE THIS MORNING. A SHORTWAVE TROUGH/DISTURBANCE WILL SWEEP THROUGH THE AREA THIS AFTERNOON RESULTING IN AFTERNOON SHOWERS AND THUNDERSTORMS. HINTED AT THIS AFTER 18Z WITH -SHRA AND CB AS CIGS FALL TO LOWER VFR RANGE. MAY NEED TO CLEARLY MENTION TS IN THE TAFS AS TIME NEARS AND THE POTENTIAL OF AN ACCURATE OCCURRENCE BECOME MORE LIKELY. THE CHANCE OF SHOWERS AND THUNDERSTORMS WILL GREATLY DECREASE ONCE AGAIN WITH THE LOSS OF DAYTIME HEATING AND THE EXITING DISTURBANCE. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... WINDS/WAVES SHOULD REMAIN FAIRLY LIGHT ACROSS THE LAKE TODAY. THE GENERAL WEATHER PATTERN SUGGESTS WINDS WILL REMAIN SOUTHERLY THROUGH SATURDAY AS HIGH PRESSURE SHIFTS EAST OF LAKE SUPERIOR. SOME BRIEF SHIFTS OF WIND WILL OCCUR ON TODAY WITH ANY SHOWERS DEVELOPMENT...BUT WINDS SHOULD GENERALLY REMAIN 20 KNOTS OR LESS THROUGH REST OF THE PERIOD. AS THE NEXT LOW PASSES THROUGH THE AREA ON SUNDAY WINDS WILL VEER NORTH. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/DISCUSSION...VOSS AVIATION...DLG MARINE...DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 530 AM EDT WED JUN 25 2008 .SYNOPSIS (ISSUED AT 420 PM EDT TUE)... WV IMAGERY AND RUC ANALYSIS INDICATED A MAINLY ZONAL PATTERN ACROSS THE NRN CONUS WITH SEVERAL SHORTWAVE TROUGHS OF NOTE. ONE SHRTWV MOVING ACROSS LAKE SUPERIOR SUPPORTED A LINE OF ISOLD SHRA EARLY THIS MORNING STRETCHING WEST TO EAST ACROSS LAKE SUPERIOR ALONG A SFC TROF INTERSECTING THE KEWEENAW PENINSULA. ANOTHER SHORTWAVE OVER SRN MANITOBA WILL BE POISED TO MOVE ACROSS THE UPR GREAT LAKES THIS AFTERNOON AND EVENING BRINGING THE POTENTIAL FOR ISOLD TO SCT SHRA/TSRA. && .DISCUSSION... TODAY...THE SRN SASK SHRTWV WILL MOVE ACROSS THE AREA. MODELS SUGGEST GREATER INSTABILITY WILL DEVELOP AS LOW LEVEL MOISTURE ADVECTS TOWARD THE WRN LAKES FROM IA AND SRN MN. FCST TEMP/DEWPOINTS NEAR 80/60 WOULD INDICATE CAPE VALUES BETWEEN 500-1000 J/KG. IF THIS INSTABILITY IS REALIZED...THERE IS SUFFICIENT DEEP LAYER SHEAR OF 40-50KT TO LEAD TO A FEW ISOLD SVR STORMS. THE BIG QUESTION IS WILL DRIER (MID-UPR 50S) DEWPOINTS MIX TO THE SFC SIMILAR TO WHAT HAPPENED YESTERDAY AND LIMIT AND/OR INHIBIT CONVECTION. LOOKING AT HOW DRY UPSTREAM 00Z SNDGS AT KINL AND KMPX ARE...I CERTAINLY THINK THAT THE NAM AND GFS MODEL DEWPOINTS ARE OVERDONE. IF DRY AIR ALOFT DOES LOWER SFC DEWPOINTS INTO THE MID-UPR 50S...IT WILL HARD TO BREAK THROUGH MID LVL CAP AT 750 MB. SPC MUST ALSO BE THINKING ALONG LINES OF A REDUCED THREAT OR DRIER SOLN AS THEY HAVE DROPPED OUR CWA OUT OF SLIGHT RISK FOR DAY1. WILL FOLLOW SUIT ON THE HWO AND DROP RISK OF SVR TODAY...BUT WILL LEAVE IN MENTION OF STRONGER STORMS CONTAINING SMALL HAIL AND GUSTY WINDS TO 50 MPH. KEPT LOW CHC POPS GOING FOR THE AFTERNOON ACROSS MUCH OF THE CWA. WED NIGHT AND THU...WILL MAINTAIN LOW CHANCE POPS FOR ANY AFTERNOON CONVECTION THAT MAY LINGER INTO THE EVENING ON TAIL END OF DEPARTING SHORTWAVE...MAINLY FOR CENTRAL AND ERN SECTIONS OF THE CWA. OTHERWISE...EXPECT DRY CONDITIONS INTO THU AS DNVA/RIDGING MOVE IN BEHIND THE SHRTWV. 850MB TEMPS AROUND 14C WILL ALLOW LOCATIONS AWAY FROM THE GREAT LAKES TO CLIMB INTO THE LOW TO MID 80S. COOLER READINGS WILL OCCUR ALONG THE GREAT LAKES SHORELINES AS LAKE BREEZES DEVELOP UNDER WEAK GRADIENT FROM HIGH PRESSURE OVERHEAD. FRI...ANOTHER SHORTWAVE EMERGES FROM THE BRITISH COLUMBIA COAST AND CARVES OUT CLOSED LOW OVER THE HIGH PLAINS BY LATE FRI INTO FRIDAY NIGHT. KEPT HIGHEST POPS FRI AFTERNOON OVER THE WEST HALF AND SPREAD LIKELY POPS ACROSS THE AREA FRI NIGHT AS MODELS SHOW IMPRESSIVE HEIGHT FALLS AHEAD OF THE APPROACHING UPR LOW. SPC STILL INDICATES A SLIGHT RISK FOR SVR STORMS ACROSS MUCH OF OUR AREA FRI AFTERNOON INTO FRI NIGHT WHICH SEEMS REASONABLE GIVEN GFS FCST OF MLCAPES OF 500-1000 J/KG AND 30-40 KT 0-6KM BULK SHEAR. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... EXPECT VFR CIGS AND VIS TO DOMINATE. THE ONLY FLY IN THE OINTMENT WILL BE A SHORTWAVE TROUGH/DISTURBANCE TUESDAY AFTERNOON. THIS SHOULD RESULT IN AFTERNOON SHOWERS AND THUNDERSTORMS. HINTED AT THIS AFTER 17Z WITH -SHRA AND CB AS CIGS FALL TO LOWER VFR RANGE. MAY NEED TO CLEARLY MENTION TS IN THE TAFS AS TIME NEARS AND THE POTENTIAL OF AN ACCURATE OCCURRENCE BECOME MORE LIKELY. THE CHANCE OF SHOWERS AND THUNDERSTORMS WILL GREATLY DECREASE ONCE AGAIN WITH THE LOSS OF DAYTIME HEATING AND THE EXITING DISTURBANCE. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... WINDS/WAVES SHOULD REMAIN FAIRLY LIGHT ACROSS THE LAKE TODAY. THE GENERAL WEATHER PATTERN SUGGESTS WINDS WILL REMAIN SOUTHERLY THROUGH SATURDAY AS HIGH PRESSURE SHIFTS EAST OF LAKE SUPERIOR. SOME BRIEF SHIFTS OF WIND WILL OCCUR ON TODAY WITH ANY SHOWERS DEVELOPMENT...BUT WINDS SHOULD GENERALLY REMAIN 20 KNOTS OR LESS THROUGH REST OF THE PERIOD. AS THE NEXT LOW PASSES THROUGH THE AREA ON SUNDAY WINDS WILL VEER NORTH. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/DISCUSSION...VOSS AVIATION...KF MARINE...DLG mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 138 AM EDT TUE JUN 24 2008 UPDATED FOR 06Z TAF ISSUANCE .SYNOPSIS (ISSUED AT 412 PM EDT MON)... WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM HUDSON BAY INTO THE ERN LAKES...A RIDGE FROM THE SW CONUS INTO THE UPPER MS VALLEY...AND WSW THROUGH THE NW CONUS. A SHORTWAVE TROUGH OVER FROM SRN ALBERTA INTO SW SASK IS EXPECTED TO IMPACT WEATHER OVER THE WRN LAKES TUE. AT THE SFC... HIGH PRES DOMINATED THE WRN GREAT LAKES AS ACYC NRLY FLOW HAS BROUGHT CLEARING OVER MOST OF UPPER MI. CU FIELDS HAVE DEVELOPED INLAND FROM LAKE SUPERIOR WHILE AN AREA OF FOG PERSISTED OVER CNTRL INTO SRN LAKE SUPERIOR. && .SHORT TERM...(TONIGHT AND TUESDAY) TONIGHT...DECENT RADIATIONAL COOLING CONDITIONS SHOULD ALLOW TEMPS TO FALL INTO THE MID AND UPPER 40S...EXCEPT OVER THE WEST WHERE INCREASE IN SRLY WINDS LATE AND POTENTIAL FOR SOME HIGH CLOUDS WILL KEEP READINGS IN THE LOWER 50S. TUESDAY...ALTHOUGH THE STRONGEST FORCING REMAINS MAINLY NORTH OF THE CWA...QG FORCING...UPPER LEVEL DIV WITH JET LEFT EXIT REGION AND 300K-305 ISENTROPIC LIFT AHEAD OF THE SASK SHRTWV MAY BE ENOUGH TO BRING SOME PCPN INTO WRN LAKE SUPERIOR LATE TONIGHT AND INTO W UPPER MI TUE MORNING. DAYTIME HEATING AND LOW LEVEL CONV VCNTY LAKE BREEZE BOUNDARIES AND A WEAK SFC TROUGH SHOULD BE ENOUGH TO TRIGGER SCT AFTERNOON SHRA/TSRA. PROFILE USING HIGHER END SFC TEMP/DEWPOINT VALUES AROUND 77/54 WOULD GIVE MLCAPE VALUES INTO THE 500-1000 J/KG RANGE. 0-6KM BULK SHEAR VALUES TO NEAR 35 KT MAY BE SUFFICIENT FOR SOME STORM ORGANIZATION AND LOW END RISK FOR HAIL TO AROUND A HALF INCH. && .LONG TERM (TUESDAY NIGHT THROUGH DAY 7)... THROUGHOUT THIS TIME PERIOD WE CAN EXPECT ON AND OFF CHANCES FOR PRECIPITATION IN THE FORM OF SHOWERS AND THUNDERSTORMS WITH THE MOST SIGNIFICANT POPS COINCIDING WITH BROAD LOW PRESSURE ENTERING THE CWA THIS WEEKEND. FOR TUESDAY NIGHT DECIDED TO CONFINE POPS MAINLY TO EASTERN AREAS OF THE CWA AS BETTER MOISTURE AND BETTER CONVERGENCE REMAINS GENERALLY OVER THE EAST. AS SHORTWAVE FEATURE EXITS TO THE EAST...OPTED TO REMOVE POPS PAST 06Z WED. BETTER OPPORTUNITY FOR SHOWERS AND THUNDERSTORMS DURING THE DAY ON WEDNESDAY AS MID LEVEL SHORTWAVE COMBINED WITH DAY TIME HEATING WILL ALLOW FOR SHOWER/THUNDERSTORM DEVELOPMENT. A QUICK LOOK AT AREA SOUNDINGS SHOW MODEST CAPE VALUES MAINLY ACROSS THE WEST HALF...ANY SEVERE POTENTIAL WOULD BE CONFINED TO HAIL...THOUGH BE IT SMALL..AS DEEP LAYER SHEAR IN OUR AREA IS WEAK. IN FACT THE WESTERN U.P. IS IN THE SLIGHT RISK OUTLOOK DURING THIS TIME. DRIER AIR WORKS INTO THE FA ON THURSDAY AHEAD OF A BROAD UPPER LEVEL LOW PRESSURE WHICH LOOKS TO DOMINATE U.P. WEATHER THROUGH THE WEEKEND. DID INCREASE POPS A BIT ON FRIDAY AS MODEL GUIDANCE/OUTLOOK FROM SPC INDICATES SVR POTENTIAL IS QUITE GOOD. OPTED TO KEEP CHANCE WORDING FOR NOW...THINK UPCOMING SHIFTS WILL NEED TO INCREASE POPS THROUGH THE WEEKEND. LOOKING TO THE EXTENDED PERIOD...DECIDED TO ADD POPS INTO EARLY SUNDAY MORNING WITH BROAD ASCENT AND MOISTURE REMAINING OVER THE U.P. ALSO TRENDED TEMPERATURES COOLER FOR SATURDAY AND SUNDAY. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... EXPECT VFR CIGS AND VIS TO DOMINATE. THE ONLY FLY IN THE OINTMENT WILL BE A SHORTWAVE TROUGH/DISTURBANCE TUESDAY AFTERNOON. THIS SHOULD RESULT IN AFTERNOON SHOWERS AND THUNDERSTORMS. HINTED AT THIS AFTER 17Z WITH -SHRA AND CB AS CIGS FALL TO LOWER VFR RANGE. MAY NEED TO CLEARLY MENTION TS IN THE TAFS AS TIME NEARS AND THE POTENTIAL OF AN ACCURATE OCCURRENCE BECOME MORE LIKELY. THE CHANCE OF SHOWERS AND THUNDERSTORMS WILL GREATLY DECREASE ONCE AGAIN WITH THE LOSS OF DAYTIME HEATING AND THE EXITING DISTURBANCE. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... WINDS/WAVES SHOULD REMAIN FAIRLY LIGHT ACROSS THE LAKE FOR THE NEXT SEVERAL DAYS. THERE ARE SOME MINOR MODEL DIFFERENCES WITH REGARD TO WINDS AFTER TONIGHT...BUT THE GENERAL PATTERN SUGGESTS WINDS WILL TURN SOUTHERLY TONIGHT AND REMAIN THAT WAY THROUGH WED AS HIGH PRES SHIFTS EAST OF LAKE SUPERIOR. MAY SEE SOME BRIEF SHIFTS OF WIND ON TUESDAY AND AGAIN ON WED WITH ANY CONVECTION...BUT WINDS SHOULD GENERALLY REMAIN 15 KT OR LESS THROUGH WED AT LEAST. WIDESPREAD STRATUS AND FOG ARE EXPECTED TO THIS OUT LATE THIS AFTERNOON AND EVENING BUT SOME AREAS MAY PERSIST TONIGHT BEFORE DIMINISHING TUE AS SRLY WINDS INCREASE. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM...JLB LONG TERM...PEARSON AVIATION...KF MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 1042 AM CDT THU JUN 26 2008 .UPDATE... LATEST SURFACE ANALYSIS SHOWS A WEAK RIDGE OF HIGH PRESSURE CENTERED NEAR THE BRAINERD LAKES AREA. HIGH CLOUDS CONTINUE TO INCREASE ACROSS THE REGION...ESPECIALLY IN THE SOUTH AND WEST...MAINLY CIRRUS DEBRIS FROM CONVECTIVE COMPLEXES THAT WILL REMAIN WELL SOUTH OF OUR AREA THROUGH THE AFTERNOON. STILL...EXPECTING HIGH CLOUDS TO CONTINUE STREAMING ACROSS THE AREA...FROM SOUTH TO NORTH...THROUGH THE DAY...AND HAVE BUMPED UP SKY COVER ACCORDINGLY. ALSO RAISED AFTERNOON MAX TEMPS SLIGHTLY BASED ON CURRENT TRENDS...MAINLY JUST 1-2 DEGREES...PERHAPS A TAD MORE ALONG THE NORTH SHORE. SILVER BAY HAD ALREADY REACHED 79 AT 15Z...BUT A LAKE BREEZE SHOULD DEVELOP WITHIN THE NEXT FEW HOURS. LATEST RUC AND NAM GUIDANCE PROPAGATES A MID LEVEL SHORTWAVE CURRENTLY OVER EASTERN NORTH DAKOTA/WESTERN MINNESOTA INTO THE BORDERLAND THIS AFTERNOON. WHILE MID-HIGH CLOUDS WILL LIKELY INCREASE WITH THIS FEATURE...NOT EXPECTING MORE THAN ISOLATED SHOWERS OR THUNDERSTORMS...AS THIS FEATURE WILL BE RUNNING INTO INCREASINGLY DRY AIR AND RATHER MARGINAL INSTABILITY. DID BRING SILENT POPS A BIT FURTHER EAST. && .PREV DISCUSSION... /ISSUED 345 AM CDT THU JUN 26 2008/ DISCUSSION... RUC13 ANALYSIS EARLY THIS MORNING INDICATES TEMPORARY RIDGING IN MID LVLS WITH ASSOCIATED DEEPENING OF NWRLY FLOW. ALTHOUGH SFC FLOW HAS DECOUPLED...WSRVWPDLH SHOWS AVERAGE 320/20KT FLOW FROM 2K TO 5K FT. TOUGH CALL ON EARLY MORNING FOG AS POTENTIAL TURBULENT KINETIC ENERGY FROM STRONGER WINDS JUST ABOVE GROUND LVL MAY GENERATE JUST ENOUGH MIXING TO KEEP WIDESPREAD FOG FORMATION. WITH SFC T/TD SPREADS ALREADY LESS THAN 2 DEGREES IN MOST OF NORTHEAST MN...WILL MENTION AREAS OF FOG. HOWEVER...CONFIDENCE NOT VERY HIGH. TODAY...LARGE MASS OF DEBRIS CLOUDS HEADING TOWARDS WRN CWA THIS MORNING FROM NEBRASKA CONVECTION. 85/30H THICKNESS PATTERN SUGGESTS THIS CONVECTION WILL TRANSLATE EASTWARD THIS MORNING...OUTRUNNING THE LLJ AND MSTR TRANSPORT MAXIMUM FARTHER WEST. OTHERWISE...FAIRLY QUIET DAY AS LL WINDS EVENTUALLY SHIFT INTO SOUTHEAST ACROSS MN ZONES AND HUMIDITY INCREASES ONCE AGAIN. CONSENSUS OF MDLS IS THAT AREA WILL REMAIN QPF FREE TODAY. SIM WRF REFLECTIVITY PRODUCT DOES GENERATE CONVECTION LATE TODAY NEAR KOOCH COUNTY HOWEVER IT DOES NOT SEEM TO HAVE INITIAL SITUATION HANDLED VERY WELL. EXPECT WARM TEMPS TODAY ALTHOUGH NOT QUITE AS WARM AS YESTERDAY AS LL THICKNESS/85H TEMPS HAVE DROPPED SEVERAL DEGREES. TONIGHT/FRIDAY...MODELS GENERALLY AGREE ON MAIN SYNOPTIC FEATURES/MASS FIELDS. SIGNIFICANT PROBLEMS ARISE WITH MULTIPLE CONVECTIVE FEEDBACK ISSUES ON GFS..AND PERHAPS EC AS WELL. WILL USE A MORE AVERAGE APPROACH AS DEPICTED BY LATEST SREF/UKM. THIS BRINGS A DEEPENING ELONGATED SFC LOW PRESSURE INTO THE WRN CWA BY EARLY FRIDAY MORNING. SFC PATTERN IS COMPLICATED BY POTENTIAL PHASING OF TWO SEPARATE SHORTWAVES...ONE DROPPING SOUTHEAST FROM MANITOBA AND ONE EJECTING FROM PLAINS. LOOKS LIKE AN OCCLUDED FRONT WILL SWEEP ACROSS THE REGION FRIDAY WITH TRIPLE POINT NEAR TWIN PORTS BY MIDDAY...REDEVELOPING TOWARDS NWRN WISC BY FRIDAY AFTERNOON.SPC HAS SLIGHT RISK OF SVR OVER SWRN CRNR OF CWA...EXTENDING TO SRN BURNETT CO. BY 12Z FRI. DURING THE DAY FRIDAY...ENTIRE CWA IS UNDER SLIGHT RISK. IT APPEARS MOST LIKELY AREA FOR THREAT WILL BE SOUTH OF TWIN PORTS AND INTO WISCONSIN FRIDAY AFTERNOON. THIS IS WHERE SREF IS INDICATING HIGHER PROBABILITY OF SBCAPE. EXTENDED...AS ADVERTISED WITH GOOD CONSISTENCY AMONG MDL SUITE...ANOMALOUS MID LVL LOW WILL SWEEP INTO REGION FOR THE WEEKEND. EXPECT SIGNIFICANT DROP IN TEMPS AND LIKELIHOOD OF SHOWERS/TRW WITH STEEPENING LAPSE RATES SATURDAY. SUNDAY SHOULD BRING SOME DECREASE IN DEEP LAYER MOISTURE WITH DECREASING CHANCE OF POPS. MONDAY/TUESDAY SHOULD BE PLEASANT WITH SUNSHINE RETURNING AND TEMPS REBOUNDING INTO 80S BY TUESDAY. AVIATION... AFTER SOME PATCHY EARLY MORNING FOG...HIGH PRESSURE WILL PROVIDE VFR CONDITIONS TODAY INTO THIS EVENING. AN AREA OF LOW PRESSURE AND A WARM FRONT WILL MOVE NORTH INTO SOUTHERN MINNESOTA AND WISCONSIN OVERNIGHT. THUNDERSTORMS WILL DEVELOP ALONG AND NORTH OF THE FRONT...AND MVFR CONDITIONS WILL DEVELOP...MAINLY AROUND KBRD EAST TOWARD KHYR. WINDS OFF OF LAKE SUPERIOR MAY CAUSE MARINE BASED MVFR OR IFR CEILINGS AND SOME FOG LATE THURSDAY NIGHT...AND THAT WILL AFFECT KDLH/KASX AND POSSIBLY INTO KHIB. && POINT TEMPS/POPS... DLH 81 56 69 51 / 10 30 60 40 INL 82 52 74 55 / 10 30 60 50 BRD 83 60 75 55 / 10 70 60 30 HYR 84 56 74 55 / 10 50 60 40 ASX 80 56 73 53 / 10 20 60 40 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. $$ BETTWY mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 121 AM CDT THU JUN 26 2008 .UPDATE... RAISED OVERNIGHT MINS A FEW DEGREES AS LL HUMIDITY IS SLOW TO EXIT CWA. CLEARING HAS ALLOWED SFC T/TD TO QUICKLY APPROACH SATURATION ACROSS PARTS OF ARROWHEAD/RANGE/WEST TO CASS LAKE. HAVE INTRODUCED AREAS OF FOG OVERNIGHT HOWEVER RUC13 925H WINDS STILL NW AT 15-20KTS. NOT SURE IF THIS WILL IMPART ENOUGH TURBULENT KINETIC ENERGY TO RESTRICT ANY SIGNIFICANT AREAL COVERAGE OF FOG. AN ARE OF MID CLOUDS WILL SCOOT RAPIDLY ACROSS NRN CWA OVERNIGHT...ALSO TEMPERING RADIATIONAL COOLING SLIGHTLY. && .PREV DISCUSSION... /ISSUED 925 PM CDT WED JUN 25 2008/ UPDATE...THUNDERSTORMS THAT FIRED ALONG WARM FRONT DURING THE MID-AFTERNOON NEAR THE INTERNATIONAL BORDER HAS DECREASED OR HAS MOVED OUT INTO LAKE SUPERIOR. WITH THE SOLAR HEATING DECREASING AND THE CAP OVER AREA...THERE SHOULD BE LITTLE DEVELOPMENT OVERNIGHT AS RIDGE BUILDS INTO AREA. THIS WILL GIVE FORECAST AREA A BREAK DURING THE DAY THURSDAY BEFORE NEXT LOW PRESSURE APPROACHS THE AREA THURSDAY EVENING GIVING THE AREA ANOTHER SHOT FOR SEVERE WEATHER THURSDAY NIGHT AND FRIDAY. REST OF FCST UNCHANGED. STEWART PREV DISCUSSION... /ISSUED 308 PM CDT WED JUN 25 2008/ DISCUSSION... CURRENT SFC ANALYSIS DEPICTING LOW PRESSURE CENTERED NEAR KINL...WITH WEAK COLD FRONT DRAPED SOUTH THROUGH KHIB TO KROS. EARLIER OVERRUNNING CONVECTION FROM THIS MORNING HAS MOVED EAST OF THE ARROWHEAD REGION. SEVERE WX PARAMETERS THROUGH LATE THIS AFTERNOON FOCUSED ON THE ARROWHEAD REGION...AS WELL AS NW WI...THOUGH FORCING FOR CONVECTION QUESTIONABLE OVER NW WI. MSAS ANALYSIS DEPICTING TONGUE OF HIGHEST POTENTIAL TEMPS AND TD`S EXTENDING NORTH THROUGH CENTRAL ST LOUIS COUNTY. LATEST RUC SOUNDINGS FROM KELO DEPICTING LI VALUES -3 TO -4 THROUGH LATE THIS AFTERNOON. DEEP LAYER SHEAR OF 40 TO 50 KTS WILL BE CONDUCIVE FOR SEVERE THUNDERSTORMS. LOW PRESSURE AND ATTENDANT COLD FRONT MOVE EAST OVERNIGHT... ALLOWING FOR HIGH PRESSURE TO BUILD IN. A WARM AND PLEASANT DAY ON TAP FOR THURSDAY BEFORE NEXT SYSTEM AFFECTS THE NORTHLAND. STRONG WAVE PROGGED TO DROP SOUTHEASTWARD FROM CANADA ON FRIDAY. RETURN FLOW FROM THE SOUTH OVERNIGHT THURSDAY...AND APPROACHING LOW PRESSURE WILL TRIGGER TS OVER THE DAKOTAS THURSDAY NIGHT. SRLY LLJ INCREASES TO 50KTS FRI MORNING ACROSS CENTRAL MN...WITH ONGOING SHOWERS AND THUNDERSTORMS QUICKLY PROPAGATING THROUGH CWA. ATTM... BEST CHANCE FOR SEVERE IS ACROSS SW CWA...WHERE MAX INSTABILITY AND LIFT IS FOCUSED. SEE DAY 2 OUTLOOK ISSUED BY SPC FOR DETAILS. INTRODUCED LIKELY POPS ON FRIDAY...AS MODELS ARE IN DECENT AGREEMENT ON PLACEMENT OF SYNOPTIC FEATURES. CONFIDENCE NOT AS GREAT FRI EVENING...AS GFS SHOWING STRONGER DOUBLE BARREL LOW DEVELOPING AND DRY SLOT PUNCHING INTO SRN ZONES...WITH ECMWF SLIGHTLY WEAKER WITH SFC FEATURE. WEEKEND SHAPING UP TO BE COOL AND WET AS UPPER LOW BECOMES QUASI STATIONARY OVER THE UPPER GREAT LAKES. ECMWF SLIGHTLY FASTER WITH MOVING THE SYSTEM OUT BY SUNDAY...WITH GFS HANGING ON THROUGH EARLY MONDAY. EITHER WAY...SHOULD SEE BELOW NORMAL TEMPS THIS WEEKEND. AVIATION... SCATTERED THUNDERSTORMS WITH GUSTY WINDS AND MVFR/IFR VSBYS/CIGS ARE EXPECTED TO DEVELOP THIS AFTERNOON ALONG A COLD FRONT TRACKING SOUTHEAST ACROSS THE NORTHLAND. THE STORMS WILL MOVE SOUTHEAST WITH THE FRONT THIS EVENING...AND SHOULD MOVE SOUTH OF THE AREA AFTER MIDNIGHT. THERE IS A SLIGHT RISK THAT SOME STORMS MAY BE SEVERE WITH LARGE HAIL AND DAMAGING WINDS. HIGH PRESSURE WILL BUILD IN OVER THE REGION BY THURSDAY RESULTING IN DRY CONDITIONS. SKIES SHOULD CLEAR OUT TONIGHT AND WINDS WILL BECOME LIGHT...ALLOWING FOR THE FORMATION OF FOG WITH IFR/MVFR VSBYS LATE TONIGHT AND EARLY THURSDAY MORNING. && POINT TEMPS/POPS... DLH 80 53 69 54 / 10 20 60 30 INL 82 56 74 54 / 10 20 60 40 BRD 83 60 75 56 / 10 50 50 30 HYR 83 55 74 55 / 10 40 60 30 ASX 79 56 73 54 / 10 10 60 40 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. $$ CANNON mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 925 PM CDT WED JUN 25 2008 .UPDATE...THUNDERSTORMS THAT FIRED ALONG WARM FRONT DURING THE MID-AFTERNOON NEAR THE INTERNATIONAL BORDER HAS DECREASED OR HAS MOVED OUT INTO LAKE SUPERIOR. WITH THE SOLAR HEATING DECREASING AND THE CAP OVER AREA...THERE SHOULD BE LITTLE DEVELOPMENT OVERNIGHT AS RIDGE BUILDS INTO AREA. THIS WILL GIVE FORECAST AREA A BREAK DURING THE DAY THURSDAY BEFORE NEXT LOW PRESSURE APPROACHS THE AREA THURSDAY EVENING GIVING THE AREA ANOTHER SHOT FOR SEVERE WEATHER THURSDAY NIGHT AND FRIDAY. REST OF FCST UNCHANGED. STEWART && .PREV DISCUSSION... /ISSUED 308 PM CDT WED JUN 25 2008/ DISCUSSION... CURRENT SFC ANALYSIS DEPICTING LOW PRESSURE CENTERED NEAR KINL...WITH WEAK COLD FRONT DRAPED SOUTH THROUGH KHIB TO KROS. EARLIER OVERRUNNING CONVECTION FROM THIS MORNING HAS MOVED EAST OF THE ARROWHEAD REGION. SEVERE WX PARAMETERS THROUGH LATE THIS AFTERNOON FOCUSED ON THE ARROWHEAD REGION...AS WELL AS NW WI...THOUGH FORCING FOR CONVECTION QUESTIONABLE OVER NW WI. MSAS ANALYSIS DEPICTING TONGUE OF HIGHEST POTENTIAL TEMPS AND TD`S EXTENDING NORTH THROUGH CENTRAL ST LOUIS COUNTY. LATEST RUC SOUNDINGS FROM KELO DEPICTING LI VALUES -3 TO -4 THROUGH LATE THIS AFTERNOON. DEEP LAYER SHEAR OF 40 TO 50 KTS WILL BE CONDUCIVE FOR SEVERE THUNDERSTORMS. LOW PRESSURE AND ATTENDANT COLD FRONT MOVE EAST OVERNIGHT... ALLOWING FOR HIGH PRESSURE TO BUILD IN. A WARM AND PLEASANT DAY ON TAP FOR THURSDAY BEFORE NEXT SYSTEM AFFECTS THE NORTHLAND. STRONG WAVE PROGGED TO DROP SOUTHEASTWARD FROM CANADA ON FRIDAY. RETURN FLOW FROM THE SOUTH OVERNIGHT THURSDAY...AND APPROACHING LOW PRESSURE WILL TRIGGER TS OVER THE DAKOTAS THURSDAY NIGHT. SRLY LLJ INCREASES TO 50KTS FRI MORNING ACROSS CENTRAL MN...WITH ONGOING SHOWERS AND THUNDERSTORMS QUICKLY PROPAGATING THROUGH CWA. ATTM... BEST CHANCE FOR SEVERE IS ACROSS SW CWA...WHERE MAX INSTABILITY AND LIFT IS FOCUSED. SEE DAY 2 OUTLOOK ISSUED BY SPC FOR DETAILS. INTRODUCED LIKELY POPS ON FRIDAY...AS MODELS ARE IN DECENT AGREEMENT ON PLACEMENT OF SYNOPTIC FEATURES. CONFIDENCE NOT AS GREAT FRI EVENING...AS GFS SHOWING STRONGER DOUBLE BARREL LOW DEVELOPING AND DRY SLOT PUNCHING INTO SRN ZONES...WITH ECMWF SLIGHTLY WEAKER WITH SFC FEATURE. WEEKEND SHAPING UP TO BE COOL AND WET AS UPPER LOW BECOMES QUASI STATIONARY OVER THE UPPER GREAT LAKES. ECMWF SLIGHTLY FASTER WITH MOVING THE SYSTEM OUT BY SUNDAY...WITH GFS HANGING ON THROUGH EARLY MONDAY. EITHER WAY...SHOULD SEE BELOW NORMAL TEMPS THIS WEEKEND. AVIATION... SCATTERED THUNDERSTORMS WITH GUSTY WINDS AND MVFR/IFR VSBYS/CIGS ARE EXPECTED TO DEVELOP THIS AFTERNOON ALONG A COLD FRONT TRACKING SOUTHEAST ACROSS THE NORTHLAND. THE STORMS WILL MOVE SOUTHEAST WITH THE FRONT THIS EVENING...AND SHOULD MOVE SOUTH OF THE AREA AFTER MIDNIGHT. THERE IS A SLIGHT RISK THAT SOME STORMS MAY BE SEVERE WITH LARGE HAIL AND DAMAGING WINDS. HIGH PRESSURE WILL BUILD IN OVER THE REGION BY THURSDAY RESULTING IN DRY CONDITIONS. SKIES SHOULD CLEAR OUT TONIGHT AND WINDS WILL BECOME LIGHT...ALLOWING FOR THE FORMATION OF FOG WITH IFR/MVFR VSBYS LATE TONIGHT AND EARLY THURSDAY MORNING. && POINT TEMPS/POPS... DLH 54 81 53 69 / 10 10 20 60 INL 51 82 56 74 / 10 10 20 60 BRD 58 84 60 75 / 10 10 50 50 HYR 55 84 55 74 / 10 10 40 60 ASX 54 80 56 73 / 10 10 10 60 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. $$ STEWART mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 308 PM CDT WED JUN 25 2008 .DISCUSSION... CURRENT SFC ANALYSIS DEPICTING LOW PRESSURE CENTERED NEAR KINL...WITH WEAK COLD FRONT DRAPED SOUTH THROUGH KHIB TO KROS. EARLIER OVERRUNNING CONVECTION FROM THIS MORNING HAS MOVED EAST OF THE ARROWHEAD REGION. SEVERE WX PARAMETERS THROUGH LATE THIS AFTERNOON FOCUSED ON THE ARROWHEAD REGION...AS WELL AS NW WI...THOUGH FORCING FOR CONVECTION QUESTIONABLE OVER NW WI. MSAS ANALYSIS DEPICTING TONGUE OF HIGHEST POTENTIAL TEMPS AND TD`S EXTENDING NORTH THROUGH CENTRAL ST LOUIS COUNTY. LATEST RUC SOUNDINGS FROM KELO DEPICTING LI VALUES -3 TO -4 THROUGH LATE THIS AFTERNOON. DEEP LAYER SHEAR OF 40 TO 50 KTS WILL BE CONDUCIVE FOR SEVERE THUNDERSTORMS. LOW PRESSURE AND ATTENDANT COLD FRONT MOVE EAST OVERNIGHT... ALLOWING FOR HIGH PRESSURE TO BUILD IN. A WARM AND PLEASANT DAY ON TAP FOR THURSDAY BEFORE NEXT SYSTEM AFFECTS THE NORTHLAND. STRONG WAVE PROGGED TO DROP SOUTHEASTWARD FROM CANADA ON FRIDAY. RETURN FLOW FROM THE SOUTH OVERNIGHT THURSDAY...AND APPROACHING LOW PRESSURE WILL TRIGGER TS OVER THE DAKOTAS THURSDAY NIGHT. SRLY LLJ INCREASES TO 50KTS FRI MORNING ACROSS CENTRAL MN...WITH ONGOING SHOWERS AND THUNDERSTORMS QUICKLY PROPAGATING THROUGH CWA. ATTM... BEST CHANCE FOR SEVERE IS ACROSS SW CWA...WHERE MAX INSTABILITY AND LIFT IS FOCUSED. SEE DAY 2 OUTLOOK ISSUED BY SPC FOR DETAILS. INTRODUCED LIKELY POPS ON FRIDAY...AS MODELS ARE IN DECENT AGREEMENT ON PLACEMENT OF SYNOPTIC FEATURES. CONFIDENCE NOT AS GREAT FRI EVENING...AS GFS SHOWING STRONGER DOUBLE BARREL LOW DEVELOPING AND DRY SLOT PUNCHING INTO SRN ZONES...WITH ECMWF SLIGHTLY WEAKER WITH SFC FEATURE. WEEKEND SHAPING UP TO BE COOL AND WET AS UPPER LOW BECOMES QUASI STATIONARY OVER THE UPPER GREAT LAKES. ECMWF SLIGHTLY FASTER WITH MOVING THE SYSTEM OUT BY SUNDAY...WITH GFS HANGING ON THROUGH EARLY MONDAY. EITHER WAY...SHOULD SEE BELOW NORMAL TEMPS THIS WEEKEND. && .AVIATION... SCATTERED THUNDERSTORMS WITH GUSTY WINDS AND MVFR/IFR VSBYS/CIGS ARE EXPECTED TO DEVELOP THIS AFTERNOON ALONG A COLD FRONT TRACKING SOUTHEAST ACROSS THE NORTHLAND. THE STORMS WILL MOVE SOUTHEAST WITH THE FRONT THIS EVENING...AND SHOULD MOVE SOUTH OF THE AREA AFTER MIDNIGHT. THERE IS A SLIGHT RISK THAT SOME STORMS MAY BE SEVERE WITH LARGE HAIL AND DAMAGING WINDS. HIGH PRESSURE WILL BUILD IN OVER THE REGION BY THURSDAY RESULTING IN DRY CONDITIONS. SKIES SHOULD CLEAR OUT TONIGHT AND WINDS WILL BECOME LIGHT...ALLOWING FOR THE FORMATION OF FOG WITH IFR/MVFR VSBYS LATE TONIGHT AND EARLY THURSDAY MORNING. && POINT TEMPS/POPS... DLH 54 81 53 69 / 10 10 20 60 INL 51 82 56 74 / 10 10 20 60 BRD 58 84 60 75 / 10 10 50 50 HYR 55 84 55 74 / 10 10 40 60 ASX 54 80 56 73 / 10 10 10 60 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. $$ LONKA/BERDES mn AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DULUTH MN 1000 AM CDT WED JUN 25 2008 .UPDATE... ONGOING ELEVATED CONVECTION IN TIP OF THE ARROWHEAD SHOULD BEGIN TO TAPER OFF BY LATE MORNING. EXPECT REDEVELOPMENT AFT 18Z IN THE ARROWHEAD AS WELL AS NORTHWEST WISCONSIN...WHERE FORCING AND MOISTURE WILL BE MAXIMIZED. DEEP LAYER SHEAR OF 40-50KT AND CAPE VALUES OF 1500-2500J/KG SUFFICIENT FOR SCATTERED SEVERE THUNDERSTORMS HERE. TOOK MENTION OF TSRA OUT OF WRN ZONES THIS AFTERNOON...AS LATEST RUC/NAM SOUNDINS SHOWING DRY AIR MOVING IN. && .PREV DISCUSSION... /ISSUED 318 AM CDT WED JUN 25 2008/ DISCUSSION...MAIN FORECAST CHALLENGE IS RESOLVING CONVECTIVE CHANCES IN THE SHORT TERM. DLH FORECAST AREA REMAINS UNDER ACTIVE ZONAL FLOW ALOFT. MOSAIC REGIONAL RADAR SHOWS NON-SEVERE CONVECTIVE COMPLEX CONTINUING EASTWARD AFFECTING THE SW FA THIS EARLY MORNING. ASSOCIATED VORT MAX IS WEAKENING...RESULTING IN CONTINUE DECAY OF THIS MCS THIS MORNING. MEANWHILE...NEXT MORE POTENT VORT MAX ATTM IS PUSHING THROUGH SOUTHERN MANITOBA/NORTH DAKOTA PER WATER VAPOR IMAGERY. NOSE OF 30+ KT LOW LEVEL JET AHEAD OF THIS SHORT WAVE HAS TRIGGERED SOME ELEVATED CONVECTION ACROSS NORTHWEST MINNESOTA THIS EARLY MORNING AS WELL. THIS CONVECTIVE ACTIVITY LOOKS TO CONTINUE ENE TRAJECTORY ALONG AND NORTH OF THE INTERNATIONAL BORDER AS LLJ VEERS THIS MORNING. WITH CONTINUED LOW LEVEL WARM AIR/THETA-E ADVECTION TODAY AHEAD OF MAIN SFC TROUGH/COLD FRONT...INSTABILITY REALLY INCREASES...WITH NAM FORECAST SOUNDINGS SHOWING SBCAPES OF 2500-3000 J/KG ACROSS THE EASTERN FA THIS AFTERNOON. DEEP LAYER SHEAR IS MODERATE TO GOOD WITH 0-6 KM SHEAR VALUES OF 35 TO 50 KT THIS AFTERNOON...SUFFICIENT FOR ORGANIZED STRONG TO SEVERE CONVECTION. THIS FRONT AND CONVECTION SHOULD PUSH OFF TO THE SOUTHEAST LATE THIS EVENING...WITH COOLER HIGH PRESSURE BUILDING IN FROM THE NORTH. PATCHY FOG MAY BE POSSIBLE...DEPENDING ON THE AMOUNT OF RAIN RECEIVED...WITH MAINLY CLEAR SKIES AND LIGHT WINDS OVERNIGHT. THURSDAY LOOKS QUIET ATTM WITH MAIN BAROCLINIC ZONE REMAINING STRETCHED ACROSS SOUTHERN MINNESOTA/SOUTHERN WISCONSIN...AND HIGH PRESSURE ACROSS THE NORTHLAND. WILL SEE A STRONG THETA-E RIDGE BUILDING ACROSS THE NORTHERN PLAINS THURSDAY NIGHT AND FRIDAY IN RESPONSE TO NEXT DEEPENING TROUGH. STRONG LIFT...ALONG WITH AMPLE MOISTURE SHOULD BRING WIDESPREAD CONVECTION TO THE FA THURSDAY NIGHT INTO FRIDAY. THE TROUGH DEEPENS BECOMING A CLOSED LOW OVER MINNESOTA/WISCONSIN FRIDAY NIGHT AND SATURDAY. THERE ARE SOME MODEL DIFFERENCES STILL WITH THE TIMING ON THE DEPARTURE OF THIS LOW...BUT IT LOOKS LIKE A COOLER AND WETTER WEEKEND ACROSS THE NORTHLAND ATTM. AVIATION...A TROUGH OF LOW PRESSURE WILL MOVE FROM FAR WESTERN MINNESOTA THIS MORNING...TO FAR EASTERN MINNESOTA BY LATE AFTERNOON...THEN THROUGH WESTERN WISCONSIN THIS EVENING. THUNDERSTORMS WILL BE POSSIBLE ALONG THIS TROUGH. MAINLY VFR CONDITIONS WILL PREVAIL...BUT MVFR OR EVEN SOME IFR CEILINGS AND VSBYS WILL OCCUR WITH THE STRONGER STORMS. THE CHANCE FOR STORMS WILL END FROM WEST TO EAST AS THE TROUGH PASSES THROUGH...AND SHOULD BE DONE ALL AREAS BY MIDNIGHT. PATCHY FOG WILL BE POSSIBLE LATE TONIGHT AS HIGH PRESSURE BRIEFLY BUILDS IN. && POINT TEMPS/POPS... DLH 83 56 80 55 / 30 10 10 20 INL 81 51 82 57 / 30 10 10 30 BRD 85 59 84 60 / 20 10 10 40 HYR 85 56 84 56 / 30 10 10 30 ASX 84 56 80 54 / 30 20 10 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. $$ LONKA/BERDES mn AREA FORECAST DISCUSSION...UPDATED AVIATION NATIONAL WEATHER SERVICE ST LOUIS MO 653 AM CDT THU JUN 26 2008 .DISCUSSION... /404 AM CDT THU JUN 26 2008/ SHORT DISCUSSION THIS MORNING DUE TO ACTIVE WEATHER. BROKEN LINE OF THUNDERSTORMS WILL CONTINUE SOUTH THROUGH SUNRISE. RUC IS INDICATING THAT MOST OF THE INSTABILITY IS BACK TOWARD SOUTHWEST MISSOURI...SO THINK THE PRIMARY THRUST OF THE STORMS WILL BE IN THAT DIRECTION. KEPT LIKELY/CATEGORICAL POPS GOING THRU 12Z...FADING TO MID-HIGH LIKELY AFTER 12Z. MODELS DEVELOP PLENTY OF CAPE THIS AFTERNOON IN THE HEAT OF THE DAY...AND WITH BOUNDARIES LINGERING FROM THIS MORNING`S STORMS FELT CHANCE POPS WERE PRUDENT FOR THE AFTERNOON. TONIGHT...MODEL QPF AND POPS HAVE BEEN PERFORMING POORLY AT BEST OVER THE PAST COUPLE OF NIGHTS. HAVE DECIDED TO MORE OR LESS IGNORE THE LESS THAN 20 PERCENT POPS GUIDANCE IS GIVING US IN NORTHERN AREAS AND HAVE GONE WITH HIGH CHANCE INSTEAD. THE THIRD IN THIS SERIES OF SMALL SHORTWAVES WILL MOVE FROM THE PLAINS INTO THE MIDWEST TONIGHT. OPERATIONAL MODELS ARE HINTING THAT THE FLOW WILL BECOME A BIT MORE ZONAL TONIGHT WHICH WOULD KEEP ALL OF THE PRECIP ASSOCIATED WITH THIS VORT NORTH OF THE CWFA...HOWEVER I HAVE LITTLE OR NO CONFIDENCE IN THIS SOLUTION BASED ON THE PAST COUPLE OF NIGHT`S PERFORMANCE. AM THINKING THAT THIS WILL BE TOO FAR NORTH AND THAT WE COULD GET THE SOUTHERN END OF AN MCS AS IT MOVES THROUGH CENTRAL IOWA INTO NORTHERN ILLINOIS. AS PREVIOUSLY STATED...HAVE INCREASED POPS TO HIGH CHANCE ACROSS THE NORTHERN TIER OF COUNTIES IN THE CWFA. DID NOT GO TOO HIGH ON QPF AT THIS TIME AS CONFIDENCE IS LOW...BUT DID GO HIGHER THAN HPC GUIDANCE SUGGESTED. FRIDAY NIGHT STILL LOOKS VERY WET AS THE COLD FRONT MOVES INTO MISSOURI ACCORDING TO ALL GUIDANCE. ATMOSPHERE WILL BE VERY MOIST AND UNSTABLE WITH PWATS IN EXCESS OF 2 INCHES AHEAD OF THE FRONT. HAVE INCREASED POPS SLIGHTLY TO 60-70% ACROSS THE MAJORITY OF THE AREA...AND BUMPED UP QPF SLIGHTLY AS WELL. HAVE MADE LITTLE OR NO CHANGE TO THE REMAINDER OF THE FORECAST BEYOND SATURDAY FOR THIS PACKAGE. CARNEY && .AVIATION... /642 AM CDT THU JUN 26 2008/ FOR THE 12Z TAFS... ANOTHER COMPLEX SCENARIO TODAY AND TONIGHT. MCS WHICH DROPPED SOUTH OUT OF IA OVERNIGHT HAS PRODUCED A WELL-DEFINED OUTFLOW BOUNDARY AND MESOSCALE PRESSURE SYSTEM IN ITS WAKE. DISJOINTED STRATIFORM RAIN REGION OF THE INTIAL MCS EXTENDS FROM KJEF TO AROUND 30 MILES NW OF KSTL. THE EASTERN PORTION OF THIS REGION HAS BEEN SHRIKING AS IT TRIES TO MOVE SOUTHEAST. I KEPT SOME TEMPO GROUPS FOR A FEW HOURS IN THE STL AREA TAFS WITH UNRESTRICTED VSBYS/LIGHT RAIN IN CASE SOME OF THIS HOLDS TOGETHER. OTHERWISE THE WRN PORTION OF THE OUTFLOW BNDRY REMAINS QUITE ACTIVE WITH CONVERGENCE/LIFT VIA THE WSWLY LLJ ON THIS FLANK. NEW CONVECTION IS PUSHING TOWARDS KCOU AND SHOULD IMPACT THEM AFT 13Z. AFTER 15Z ANTICIPATING AN OVERALL DIMINISHING TREND OF ANY ACTIVITY IN ERN MO AND DECREASE IN CLOUDS. IF THE RESIDUAL BNDRY REMAINS INTACT INTO THE AFTERNOON IT COULD FOCUS NEW SCATTERED THUNDERSTORM DEVELOPMENT...BUT ITS EXISTENCE AND POSSIBLE LOCATION ARE TOO IFFY TO KNOW IF ANYTHING COULD IMPACT A TAF SITE. DURING THE OVERNIGHT HOURS IT LOOKS AS IF ANOTHER MCS SHOULD DROP SEWD OUT OF IA AND POTENTIALLY AFFECT KUIN. INTRODUCED A PROB GROUP WITH THIS IN MIND. GLASS && .LSX WATCHES/WARNINGS/ADVISORIES... MO...FLASH FLOOD WATCH UNTIL NOON CDT TODAY FOR LINCOLN. IL...NONE. && $$ WFO LSX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 440 AM CDT WED JUN 25 2008 .DISCUSSION... /330 AM CDT WED JUN 25 2008/ Q-STATIONARY FRONT DRAPED ACROSS MISSOURI ALONG WITH STRONG NOCTURNAL LOW LEVEL JET HAS TOUCHED OFF A HEAVY RAIN PRODUCING MCS. THE HEAVIEST RAIN HAS BEEN FALLING ACROSS NORTH CENTRAL AND CENTRAL MISSOURI...JUST OUTSIDE OUR CWFA. HOWEVER...RADAR ESTIMATES OF 2-3 INCHES OF RAIN AT THIS TIME WITH MORE ON THE WAY ACROSS KNOX...LEWIS...MARION...SHELBY...AND ADAMS COUNTIES. HAVE THEREFORE DECIDED TO CONTINUE THE FLASH FLOOD WATCH THROUGH NOON TODAY. IT STILL LOOKS...BASED ON RADAR TRENDS...LIKE THE SOUTHERN EXTENT OF THE HEAVY RAIN WILL FALL WITHIN THE WATCH AREA THIS MORNING SO DID NOT EXPAND THE AREA AT THIS TIME. OUTFLOW BOUNDARY FROM THIS MORNING`S MCS WILL LIKELY BE HANGING AROUND THE CWFA THIS AFTERNOON. THIS BOUNDARY WOULD PROVIDE A GOOD FOCUS FOR ADDITIONAL THUNDERSTORM DEVELOPMENT. RUC IS FORECASTING MLCAPES GREATER THAN 1600 J/KG AND MUCAPES GREATER THAN 4000 JOULES BY 18Z. THIS IS OBVIOUSLY MORE THAN ENOUGH ENERGY FOR THUNDERSTORMS TO REDEVELOP. NOT SURE THOUGH WHAT THE COVERAGE WILL BE THIS AFTERNOON SO MAINLY KEPT JUST CHANCES GOING. THE SURFACE BOUNDARY MOVES FURTHER NORTH INTO IOWA TONIGHT AND APPEARS TO TAKE THE THREAT FOR HEAVY RAIN WITH IT AT LEAST THROUGH FRIDAY MORNING. THERE`S STILL THE CHANCE THAT WE`LL SEE SOME SCATTERED THUNDERSTORMS...BUT ORGANIZED MCS ACTIVITY SHOULD STAY NORTH OF THE CWFA WHERE THE LOW LEVEL JET MOVES OVERTOP OF THE BOUNDARY AND INTERACTS WITH SEVERAL PASSING SHORTWAVES. UNFORTUNATELY THIS MEANS MORE WATER IN THE MISSISSIPPI RIVER SYSTEM. NOT SURE YET HOW THIS WILL IMPACT RIVER FORECASTS...WHETHER THE RIVER WILL RISE AGAIN...OR IF IT WILL JUST DELAY THE PREVIOUSLY FORECASTED FALL. EITHER WAY THIS IS NOT GOOD NEWS. THE NEXT SHOT FOR HEAVY RAINFALL LOOKS TO BE FRIDAY NIGHT AND SATURDAY AS A SLOW MOVING COLD FRONT MOVES SOUTHEAST ACROSS MISSOURI AND ILLINOIS. HPC GUIDANCE PRINTED OUT OVER AN INCH OF QPF ACROSS THE AREA FRIDAY NIGHT. DID NOT GO THAT HIGH IN MY QPF FORECAST YET AS THERE IS STILL A LOT OF UNCERTAINTY IN THE QPF FORECAST OUT THAT FAR...THOUGH THIS IS OBVIOUSLY A POSSIBILITY THAT WILL HAVE TO BE WATCHED CLOSELY OVER THE NEXT COUPLE OF DAYS. CARNEY && .AVIATION... /1051 PM CDT TUE JUN 24 2008/ FOR THE 06Z TAFS...SCT TSRA CONT TO DVLP N OF A WRMFNT CURRENTLY EXTDG FM NR MCI SE TO NR STL...AND ALSO AHD OF AN MCV MOVG SLOWLY EWD THRU S CNTRL IA. THE SWLY LLJ IS FCST TO FOCUS BOTH LOW LVL TEMPERATURE AND MOISTURE ADVCTN TO NERN MO LT TGT. LOOKING AT LATEST RADAR TRENDS WILL INCLUDE PREVAILING TSRA IN UIN OR AT LEAST A TEMPO GRP OF TSRA IN UIN TIL AT LEAST 08Z WED. IT APRS THAT THE TSRA OVER NRN MO WILL REMAIN N OF COU..STL AND SUS LT TGT. THE BEST THREAT OF CONVECTION SHOULD SHIFT NWD ON WED AS THE WRMFNT IS FCST TO MOVE NWD THRU NRN MO LT TGT AND INTO IA ON WED. OUTSIDE OF THE STORMS THERE SHOULD BE HI LVL CONVECTIVE DEBRIS CLOUDINESS ALONG WITH SOME WAA MID LVL CLOUDINESS AS WELL. WITH THE WRMFNT LIFTING NWD THE SELY SFC WNDS AT THE TAF SITES WILL GRADUALLY VEER ARND TO A SLY DIRECTION LT TGT THEN TO A SWLY DIRECTION ON WED. GKS && .LSX WATCHES/WARNINGS/ADVISORIES... MO...FLASH FLOOD WATCH UNTIL NOON CDT TODAY FOR KNOX-LEWIS-MARION- MONROE-RALLS-SHELBY. FLASH FLOOD WATCH THROUGH THIS EVENING FOR LINCOLN. IL...FLASH FLOOD WATCH UNTIL NOON CDT TODAY FOR ADAMS IL-BROWN IL- PIKE IL. && $$ WFO LSX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HASTINGS NE 1252 AM CDT THU JUN 26 2008 .AVIATION...06Z KGRI TAF. VFR CONDITIONS FOR THIS FORECAST. WIND SHOULD REALLY START MIXING AND GUSTING FROM THE SOUTH BY THIS AFTERNOON. STORMS THEN MOVE INTO THE AREA AT THE END OF THE PERIOD...THIS EVENING AND TONIGHT. && .PREV DISCUSSION... /ISSUED 942 PM CDT WED JUN 25 2008/ DISCUSSION...DUE TO THE ONGOING CONVECTION IN NORTHWESTERN KANSAS...THIS LOOKS LIKE IT IS HOLDING TOGETHER AND COULD AFFECT PARTS OF OUR KANSAS COUNTIES AT LEAST IN THE EARLY OVERNIGHT HOURS THAT DID NOT MENTION THUNDERSTORMS IN THE PREVIOUS FORECAST. THE INCREASING LOW-LEVEL JET SHOULD HELP KEEP THESE STORMS GOING OVERNIGHT AS WELL. AS FAR AS MODELS ARE CONCERNED...QPF FIELDS ARE GENERALLY WORTHLESS AND HAVE BEEN IGNORED. PREV DISCUSSION... /ISSUED 355 PM CDT WED JUN 25 2008/ SHORT TERM...FOR TONIGHT THROUGH THURSDAY NIGHT. LATEST WATER VAPOR IMAGERY REVEALS A FAIRLY ZONAL FLOW REGIME ACROSS THE NORTHERN HALF OF THE CONUS WITH SEVERAL SMALL BUT POTENT WAVES EMBEDDED WITHIN THIS UPPER FLOW PATTERN. ONE OF THESE WAVES IS CURRENTLY SLIDING OUT OF THE HIGH PLAINS WHILE A SECOND WAVE IS SEEN PUSHING INTO THE ROCKIES. RECENT OBJECTIVE SURFACE ANALYSIS SHOWS TWO BOUNDARIES OF INTEREST ACROSS THE AREA WITH A DIFFERENTIAL HEATING BOUNDARY STRETCHING FROM NEAR MCCOOK TO AROUND GRAND ISLAND WHILE WEAK SURFACE TROUGH IS SEEN STRETCHING FROM NORTHERN IOWA INTO NORTH CENTRAL NEBRASKA. LOOKING AT RUC ANALYSIS...ML CAPES OF 3000 TO AS HIGH AS 4500 J/KG ARE SEEN FROM NORTHERN KANSAS INTO CENTRAL NEBRASKA ALTHOUGH MOST OF THIS AREA CONTINUES TO HAVE MODEST TO STRONG INHIBITION. HOWEVER...WEAKER INHIBITION IS SHOWN ACROSS NORTH CENTRAL NEBRASKA AND AGAIN ACROSS NORTHWESTERN KANSAS. TAKING A LOOK AT VISIBLE SAT IMAGERY IN THESE WEAKER INHIBITION AREAS...A SMALL CLUSTER OF CU IS VISIBLE NEAR KGLD BUT LITTLE IS SHOWN ACROSS NORTH CENTRAL NEBRASKA. MAIN QUESTION AS THE AREA HEADS INTO THIS EVENING TO OVERNIGHT IS WHERE DEEP CONVECTION MAY DEVELOP. INITIAL PROBLEM WITH DEVELOPING DEEP CONVECTION ACROSS THE AREA LATE THIS AFTERNOON TO EARLY EVENING IS THAT FORCING FROM THE FIRST WAVE MOVING THROUGH THE REGION NOW...IS SHOWN TO SLIDE EAST OF THE FORECAST AREA BY EARLY EVENING. GIVEN THE TIMING OF THIS WAVE PRODUCING INCREASING MID LEVEL SUBSIDENCE ALONG WITH A LACK OF ANY CONVECTIVE DEVELOPMENT OVER THE REGION THIS AFTERNOON...CONFIDENCE IS LOW THAT DEEP CONVECTION WILL DEVELOP THROUGH EARLY EVENING. WILL OPT TO KEEP A SLIGHT CHANCE OVER MOST OF THE CWA BUT THIS MAY NEED TO BE REMOVED BY THE EVENING SHIFT IF NOTHING DEVELOPS. IF SOMETHING DOES DEVELOP...SEVERE THREAT LOOKS MARGINAL AS EFFECTIVE DEEP LAYER SHEAR WILL REMAIN WEAK AT 15 TO 25 KNOTS AT BEST. WILL KEEP MENTION OF SEVERE BUT WILL DECREASE MAX HAIL SIZE DOWN TO PENNY TO QUARTER SIZE. HOWEVER...AS THE EVENING PROGRESSES INTO THE OVERNIGHT HOURS A 30 TO 40 KT LLJ IS SHOWN TO NOSE INTO THE AREA WITH WHATEVER CONVECTION REMAINS ACROSS THE HIGH PLAINS SLIDING EAST INTO THE CWA. COVERAGE OF STORMS LOOKS SMALL...BUT WILL KEEP A SLIGHT CHANCE OVER MOST OF THE CWA THROUGH THE NIGHT. THURSDAY AFTERNOON INTO THURSDAY NIGHT IS THEN SHAPING UP TO BE AN ACTIVE TIME FRAME ACROSS THE REGION. A WEAK AREA OF LOW PRESSURE IS SHOWN BY THE MODELS TO SPIN UP OVER NORTH CENTRAL NEBRASKA WITH A WARM FRONT SEEN EXTENDING EAST ACROSS NORTHERN NEBRASKA WHILE A DRYLINE STRETCHES SOUTH ACROSS FAR WESTERN SECTIONS OF THE FORECAST AREA GENERALLY NEAR HIGHWAY 283. DEEP LOW LEVEL MOISTURE WILL BE AVAILABLE AHEAD OF THE DRYLINE AND ON EITHER SIDE OF THE WARM FRONT. THIS IS SHOWN TO PRODUCE ML CAPES OF 2000 TO 2500 J/KG NEAR THE DRYLINE AND 3000 TO 3500 J/KG NEAR THE WARM FRONT. A HEALTHY SHORT WAVE IS SHOWN TO RIDE OUT OF THE ROCKIES INTO THE PLAINS DURING THE AFTERNOON AND EXPECT THIS TO TRIGGER ISOLATED CONVECTIVE DEVELOPMENT ALONG THE DRYLINE AND MORE SCATTERED DEVELOPMENT JUST NORTH OF THE CWA NEAR THE WARM FRONT. SEVERE CONVECTION WISE...EFFECTIVE DEEP LAYER SHEAR WILL BE RATHER WEAK ALONG DRYLINE BY MID TO LATE AFTERNOON WITH VALUES OF 10 TO 25 KNTS AT BEST. THIS SHOULD KEEP CONVECTION ON THE WEAKER SIDE OVER THIS PORTION OF FORECAST AREA. HOWEVER...WITH SURFACE WINDS BACKING AROUND TO A MORE EASTERLY DIRECTION CLOSER TO THE WARM FRONT...EFFECTIVE DEEP LAYER SHEAR OF 25 TO NEAR 40 KNTS SHOULD SUPPORT GOOD CELL ORGANIZATION AND POSSIBLE ROTATION. TORNADO THREAT LOOKS MINIMAL BUT LARGE HAIL THREAT LOOKS POSSIBLE MAINLY NORTH OF HIGHWAY 92. TEMPERATURE WISE...A VERY WARM AFTERNOON LOOKS ON TAP WITH HIGHS RANGING FROM THE LOWER TO MID 90S NEAR ORD TO OSCEOLA...TO THE MID 90S TO AROUND 100 ACROSS NORTH CENTRAL KANSAS. LONG TERM...12Z FRIDAY THROUGH WEDNESDAY. A COLD FRONT WILL BE ON TOP OF THE CWFA FRIDAY MORNING...AS MAY LEFTOVER SHOWERS AND DEBRIS CLOUDS FROM ANY THURSDAY NIGHT MCS ACTIVITY. THE MODELS ARE ALL VERY SIMILAR IN TIMING THE FRONT THROUGH ALL BUT THE FAR SOUTHEAST CFWA AS EARLY AS MIDDAY...AND THAT MAY BE TOO SLOW IF CONVECTION THURSDAY NIGHT PUSHES HAS ANY SAY. POINT IS...WITH CLOUDS LINGERING...AND FRONT ON THE MOVE...THE BEST CHANCE FOR ANY PRECIPITATION FRIDAY WILL BE EAST/SOUTHEAST CWFA. KEPT A SMALL RISK FOR FRIDAY NIGHT...IN CASE POST FRONTAL ELEVATED PRECIPITATION CAN FORM...WHICH IT OFTEN DOES FOR A TIME IN THESE SITUATIONS. THE WEEKEND LOOKS ADMIRABLE WEATHER WISE. ANOMALOUSLY DRY AIR IS FORECAST TO COME INTO THE CENTRAL PLAINS BEHIND COLD FRONT FRIDAY...DRIVEN BY GREAT LAKES REGION LOW PRESSURE. PWAT VALUES ARE FORECAST TO BE IN THE LOWER HALF OF CLIMATOLOGY VALUES. THOUGH DEWPOINTS MAY BE HELD UP SLIGHTLY WITH EVAPOTRANSPIRATION AND RECENT RAINFALL ISSUES...IT SHOULD STILL FEEL MUCH MORE PLEASANT WITH DEWPOINTS IN THE 50S FOR MOST AREAS. NEXT SHOT FOR A STORM OR TWO COULD COME MONDAY EVENING IN THE WESTERN ZONES...AS A STORM MAY FLOUNDER IN FROM THE HIGH PLAINS. LITTLE BETTER RISK OF STORMS POSSIBLE TUESDAY/WEDNESDAY...AS THE RIPPLE EFFECT RETURNS WITH A WEAK WAVE CUTTING THROUGH THE RIDGE. TEMPERATURES SHOULD GRADUALLY WARM A FEW DEGREES EACH BEGINNING SATURDAY. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ ne AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE HASTINGS NE 942 PM CDT WED JUN 25 2008 .DISCUSSION...DUE TO THE ONGOING CONVECTION IN NORTHWESTERN KANSAS...THIS LOOKS LIKE IT IS HOLDING TOGETHER AND COULD AFFECT PARTS OF OUR KANSAS COUNTIES AT LEAST IN THE EARLY OVERNIGHT HOURS THAT DID NOT MENTION THUNDERSTORMS IN THE PREVIOUS FORECAST. THE INCREASING LOW-LEVEL JET SHOULD HELP KEEP THESE STORMS GOING OVERNIGHT AS WELL. AS FAR AS MODELS ARE CONCERNED...QPF FIELDS ARE GENERALLY WORTHLESS AND HAVE BEEN IGNORED. && .PREV DISCUSSION... /ISSUED 645 PM CDT WED JUN 25 2008/ AVIATION...00Z KGRI TAF. VFR CONDITIONS FOR THIS FORECAST. THUNDERSTORM ACTIVITY LOOKS LIKE IT WILL BE MUCH LATER FOR THE AREA...AND SHOULD REMAIN PRIMARILY TO THE WEST AND SOUTHWEST OF THE TERMINAL. WIND SHOULD REALLY START MIXING AND GUSTING FROM THE SOUTH ON THURSDAY AFTERNOON. STORMS THURSDAY NIGHT SHOULD HOLD OFF UNTIL AFTER THIS FORECAST VALID TIME. PREV DISCUSSION... /ISSUED 355 PM CDT WED JUN 25 2008/ SHORT TERM...FOR TONIGHT THROUGH THURSDAY NIGHT. LATEST WATER VAPOR IMAGERY REVEALS A FAIRLY ZONAL FLOW REGIME ACROSS THE NORTHERN HALF OF THE CONUS WITH SEVERAL SMALL BUT POTENT WAVES EMBEDDED WITHIN THIS UPPER FLOW PATTERN. ONE OF THESE WAVES IS CURRENTLY SLIDING OUT OF THE HIGH PLAINS WHILE A SECOND WAVE IS SEEN PUSHING INTO THE ROCKIES. RECENT OBJECTIVE SURFACE ANALYSIS SHOWS TWO BOUNDARIES OF INTEREST ACROSS THE AREA WITH A DIFFERENTIAL HEATING BOUNDARY STRETCHING FROM NEAR MCCOOK TO AROUND GRAND ISLAND WHILE WEAK SURFACE TROUGH IS SEEN STRETCHING FROM NORTHERN IOWA INTO NORTH CENTRAL NEBRASKA. LOOKING AT RUC ANALYSIS...ML CAPES OF 3000 TO AS HIGH AS 4500 J/KG ARE SEEN FROM NORTHERN KANSAS INTO CENTRAL NEBRASKA ALTHOUGH MOST OF THIS AREA CONTINUES TO HAVE MODEST TO STRONG INHIBITION. HOWEVER...WEAKER INHIBITION IS SHOWN ACROSS NORTH CENTRAL NEBRASKA AND AGAIN ACROSS NORTHWESTERN KANSAS. TAKING A LOOK AT VISIBLE SAT IMAGERY IN THESE WEAKER INHIBITION AREAS...A SMALL CLUSTER OF CU IS VISIBLE NEAR KGLD BUT LITTLE IS SHOWN ACROSS NORTH CENTRAL NEBRASKA. MAIN QUESTION AS THE AREA HEADS INTO THIS EVENING TO OVERNIGHT IS WHERE DEEP CONVECTION MAY DEVELOP. INITIAL PROBLEM WITH DEVELOPING DEEP CONVECTION ACROSS THE AREA LATE THIS AFTERNOON TO EARLY EVENING IS THAT FORCING FROM THE FIRST WAVE MOVING THROUGH THE REGION NOW...IS SHOWN TO SLIDE EAST OF THE FORECAST AREA BY EARLY EVENING. GIVEN THE TIMING OF THIS WAVE PRODUCING INCREASING MID LEVEL SUBSIDENCE ALONG WITH A LACK OF ANY CONVECTIVE DEVELOPMENT OVER THE REGION THIS AFTERNOON...CONFIDENCE IS LOW THAT DEEP CONVECTION WILL DEVELOP THROUGH EARLY EVENING. WILL OPT TO KEEP A SLIGHT CHANCE OVER MOST OF THE CWA BUT THIS MAY NEED TO BE REMOVED BY THE EVENING SHIFT IF NOTHING DEVELOPS. IF SOMETHING DOES DEVELOP...SEVERE THREAT LOOKS MARGINAL AS EFFECTIVE DEEP LAYER SHEAR WILL REMAIN WEAK AT 15 TO 25 KNOTS AT BEST. WILL KEEP MENTION OF SEVERE BUT WILL DECREASE MAX HAIL SIZE DOWN TO PENNY TO QUARTER SIZE. HOWEVER...AS THE EVENING PROGRESSES INTO THE OVERNIGHT HOURS A 30 TO 40 KT LLJ IS SHOWN TO NOSE INTO THE AREA WITH WHATEVER CONVECTION REMAINS ACROSS THE HIGH PLAINS SLIDING EAST INTO THE CWA. COVERAGE OF STORMS LOOKS SMALL...BUT WILL KEEP A SLIGHT CHANCE OVER MOST OF THE CWA THROUGH THE NIGHT. THURSDAY AFTERNOON INTO THURSDAY NIGHT IS THEN SHAPING UP TO BE AN ACTIVE TIME FRAME ACROSS THE REGION. A WEAK AREA OF LOW PRESSURE IS SHOWN BY THE MODELS TO SPIN UP OVER NORTH CENTRAL NEBRASKA WITH A WARM FRONT SEEN EXTENDING EAST ACROSS NORTHERN NEBRASKA WHILE A DRYLINE STRETCHES SOUTH ACROSS FAR WESTERN SECTIONS OF THE FORECAST AREA GENERALLY NEAR HIGHWAY 283. DEEP LOW LEVEL MOISTURE WILL BE AVAILABLE AHEAD OF THE DRYLINE AND ON EITHER SIDE OF THE WARM FRONT. THIS IS SHOWN TO PRODUCE ML CAPES OF 2000 TO 2500 J/KG NEAR THE DRYLINE AND 3000 TO 3500 J/KG NEAR THE WARM FRONT. A HEALTHY SHORT WAVE IS SHOWN TO RIDE OUT OF THE ROCKIES INTO THE PLAINS DURING THE AFTERNOON AND EXPECT THIS TO TRIGGER ISOLATED CONVECTIVE DEVELOPMENT ALONG THE DRYLINE AND MORE SCATTERED DEVELOPMENT JUST NORTH OF THE CWA NEAR THE WARM FRONT. SEVERE CONVECTION WISE...EFFECTIVE DEEP LAYER SHEAR WILL BE RATHER WEAK ALONG DRYLINE BY MID TO LATE AFTERNOON WITH VALUES OF 10 TO 25 KNTS AT BEST. THIS SHOULD KEEP CONVECTION ON THE WEAKER SIDE OVER THIS PORTION OF FORECAST AREA. HOWEVER...WITH SURFACE WINDS BACKING AROUND TO A MORE EASTERLY DIRECTION CLOSER TO THE WARM FRONT...EFFECTIVE DEEP LAYER SHEAR OF 25 TO NEAR 40 KNTS SHOULD SUPPORT GOOD CELL ORGANIZATION AND POSSIBLE ROTATION. TORNADO THREAT LOOKS MINIMAL BUT LARGE HAIL THREAT LOOKS POSSIBLE MAINLY NORTH OF HIGHWAY 92. TEMPERATURE WISE...A VERY WARM AFTERNOON LOOKS ON TAP WITH HIGHS RANGING FROM THE LOWER TO MID 90S NEAR ORD TO OSCEOLA...TO THE MID 90S TO AROUND 100 ACROSS NORTH CENTRAL KANSAS. LONG TERM...12Z FRIDAY THROUGH WEDNESDAY. A COLD FRONT WILL BE ON TOP OF THE CWFA FRIDAY MORNING...AS MAY LEFTOVER SHOWERS AND DEBRIS CLOUDS FROM ANY THURSDAY NIGHT MCS ACTIVITY. THE MODELS ARE ALL VERY SIMILAR IN TIMING THE FRONT THROUGH ALL BUT THE FAR SOUTHEAST CFWA AS EARLY AS MIDDAY...AND THAT MAY BE TOO SLOW IF CONVECTION THURSDAY NIGHT PUSHES HAS ANY SAY. POINT IS...WITH CLOUDS LINGERING...AND FRONT ON THE MOVE...THE BEST CHANCE FOR ANY PRECIPITATION FRIDAY WILL BE EAST/SOUTHEAST CWFA. KEPT A SMALL RISK FOR FRIDAY NIGHT...IN CASE POST FRONTAL ELEVATED PRECIPITATION CAN FORM...WHICH IT OFTEN DOES FOR A TIME IN THESE SITUATIONS. THE WEEKEND LOOKS ADMIRABLE WEATHER WISE. ANOMALOUSLY DRY AIR IS FORECAST TO COME INTO THE CENTRAL PLAINS BEHIND COLD FRONT FRIDAY...DRIVEN BY GREAT LAKES REGION LOW PRESSURE. PWAT VALUES ARE FORECAST TO BE IN THE LOWER HALF OF CLIMATOLOGY VALUES. THOUGH DEWPOINTS MAY BE HELD UP SLIGHTLY WITH EVAPOTRANSPIRATION AND RECENT RAINFALL ISSUES...IT SHOULD STILL FEEL MUCH MORE PLEASANT WITH DEWPOINTS IN THE 50S FOR MOST AREAS. NEXT SHOT FOR A STORM OR TWO COULD COME MONDAY EVENING IN THE WESTERN ZONES...AS A STORM MAY FLOUNDER IN FROM THE HIGH PLAINS. LITTLE BETTER RISK OF STORMS POSSIBLE TUESDAY/WEDNESDAY...AS THE RIPPLE EFFECT RETURNS WITH A WEAK WAVE CUTTING THROUGH THE RIDGE. TEMPERATURES SHOULD GRADUALLY WARM A FEW DEGREES EACH BEGINNING SATURDAY. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ HEINLEIN ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HASTINGS NE 645 PM CDT WED JUN 25 2008 .AVIATION...00Z KGRI TAF. VFR CONDITIONS FOR THIS FORECAST. THUNDERSTORM ACTIVITY LOOKS LIKE IT WILL BE MUCH LATER FOR THE AREA...AND SHOULD REMAIN PRIMARILY TO THE WEST AND SOUTHWEST OF THE TERMINAL. WIND SHOULD REALLY START MIXING AND GUSTING FROM THE SOUTH ON THURSDAY AFTERNOON. STORMS THURSDAY NIGHT SHOULD HOLD OFF UNTIL AFTER THIS FORECAST VALID TIME. && .PREV DISCUSSION... /ISSUED 355 PM CDT WED JUN 25 2008/ SHORT TERM...FOR TONIGHT THROUGH THURSDAY NIGHT. LATEST WATER VAPOR IMAGERY REVEALS A FAIRLY ZONAL FLOW REGIME ACROSS THE NORTHERN HALF OF THE CONUS WITH SEVERAL SMALL BUT POTENT WAVES EMBEDDED WITHIN THIS UPPER FLOW PATTERN. ONE OF THESE WAVES IS CURRENTLY SLIDING OUT OF THE HIGH PLAINS WHILE A SECOND WAVE IS SEEN PUSHING INTO THE ROCKIES. RECENT OBJECTIVE SURFACE ANALYSIS SHOWS TWO BOUNDARIES OF INTEREST ACROSS THE AREA WITH A DIFFERENTIAL HEATING BOUNDARY STRETCHING FROM NEAR MCCOOK TO AROUND GRAND ISLAND WHILE WEAK SURFACE TROUGH IS SEEN STRETCHING FROM NORTHERN IOWA INTO NORTH CENTRAL NEBRASKA. LOOKING AT RUC ANALYSIS...ML CAPES OF 3000 TO AS HIGH AS 4500 J/KG ARE SEEN FROM NORTHERN KANSAS INTO CENTRAL NEBRASKA ALTHOUGH MOST OF THIS AREA CONTINUES TO HAVE MODEST TO STRONG INHIBITION. HOWEVER...WEAKER INHIBITION IS SHOWN ACROSS NORTH CENTRAL NEBRASKA AND AGAIN ACROSS NORTHWESTERN KANSAS. TAKING A LOOK AT VISIBLE SAT IMAGERY IN THESE WEAKER INHIBITION AREAS...A SMALL CLUSTER OF CU IS VISIBLE NEAR KGLD BUT LITTLE IS SHOWN ACROSS NORTH CENTRAL NEBRASKA. MAIN QUESTION AS THE AREA HEADS INTO THIS EVENING TO OVERNIGHT IS WHERE DEEP CONVECTION MAY DEVELOP. INITIAL PROBLEM WITH DEVELOPING DEEP CONVECTION ACROSS THE AREA LATE THIS AFTERNOON TO EARLY EVENING IS THAT FORCING FROM THE FIRST WAVE MOVING THROUGH THE REGION NOW...IS SHOWN TO SLIDE EAST OF THE FORECAST AREA BY EARLY EVENING. GIVEN THE TIMING OF THIS WAVE PRODUCING INCREASING MID LEVEL SUBSIDENCE ALONG WITH A LACK OF ANY CONVECTIVE DEVELOPMENT OVER THE REGION THIS AFTERNOON...CONFIDENCE IS LOW THAT DEEP CONVECTION WILL DEVELOP THROUGH EARLY EVENING. WILL OPT TO KEEP A SLIGHT CHANCE OVER MOST OF THE CWA BUT THIS MAY NEED TO BE REMOVED BY THE EVENING SHIFT IF NOTHING DEVELOPS. IF SOMETHING DOES DEVELOP...SEVERE THREAT LOOKS MARGINAL AS EFFECTIVE DEEP LAYER SHEAR WILL REMAIN WEAK AT 15 TO 25 KNOTS AT BEST. WILL KEEP MENTION OF SEVERE BUT WILL DECREASE MAX HAIL SIZE DOWN TO PENNY TO QUARTER SIZE. HOWEVER...AS THE EVENING PROGRESSES INTO THE OVERNIGHT HOURS A 30 TO 40 KT LLJ IS SHOWN TO NOSE INTO THE AREA WITH WHATEVER CONVECTION REMAINS ACROSS THE HIGH PLAINS SLIDING EAST INTO THE CWA. COVERAGE OF STORMS LOOKS SMALL...BUT WILL KEEP A SLIGHT CHANCE OVER MOST OF THE CWA THROUGH THE NIGHT. THURSDAY AFTERNOON INTO THURSDAY NIGHT IS THEN SHAPING UP TO BE AN ACTIVE TIME FRAME ACROSS THE REGION. A WEAK AREA OF LOW PRESSURE IS SHOWN BY THE MODELS TO SPIN UP OVER NORTH CENTRAL NEBRASKA WITH A WARM FRONT SEEN EXTENDING EAST ACROSS NORTHERN NEBRASKA WHILE A DRYLINE STRETCHES SOUTH ACROSS FAR WESTERN SECTIONS OF THE FORECAST AREA GENERALLY NEAR HIGHWAY 283. DEEP LOW LEVEL MOISTURE WILL BE AVAILABLE AHEAD OF THE DRYLINE AND ON EITHER SIDE OF THE WARM FRONT. THIS IS SHOWN TO PRODUCE ML CAPES OF 2000 TO 2500 J/KG NEAR THE DRYLINE AND 3000 TO 3500 J/KG NEAR THE WARM FRONT. A HEALTHY SHORT WAVE IS SHOWN TO RIDE OUT OF THE ROCKIES INTO THE PLAINS DURING THE AFTERNOON AND EXPECT THIS TO TRIGGER ISOLATED CONVECTIVE DEVELOPMENT ALONG THE DRYLINE AND MORE SCATTERED DEVELOPMENT JUST NORTH OF THE CWA NEAR THE WARM FRONT. SEVERE CONVECTION WISE...EFFECTIVE DEEP LAYER SHEAR WILL BE RATHER WEAK ALONG DRYLINE BY MID TO LATE AFTERNOON WITH VALUES OF 10 TO 25 KNTS AT BEST. THIS SHOULD KEEP CONVECTION ON THE WEAKER SIDE OVER THIS PORTION OF FORECAST AREA. HOWEVER...WITH SURFACE WINDS BACKING AROUND TO A MORE EASTERLY DIRECTION CLOSER TO THE WARM FRONT...EFFECTIVE DEEP LAYER SHEAR OF 25 TO NEAR 40 KNTS SHOULD SUPPORT GOOD CELL ORGANIZATION AND POSSIBLE ROTATION. TORNADO THREAT LOOKS MINIMAL BUT LARGE HAIL THREAT LOOKS POSSIBLE MAINLY NORTH OF HIGHWAY 92. TEMPERATURE WISE...A VERY WARM AFTERNOON LOOKS ON TAP WITH HIGHS RANGING FROM THE LOWER TO MID 90S NEAR ORD TO OSCEOLA...TO THE MID 90S TO AROUND 100 ACROSS NORTH CENTRAL KANSAS. LONG TERM...12Z FRIDAY THROUGH WEDNESDAY. A COLD FRONT WILL BE ON TOP OF THE CWFA FRIDAY MORNING...AS MAY LEFTOVER SHOWERS AND DEBRIS CLOUDS FROM ANY THURSDAY NIGHT MCS ACTIVITY. THE MODELS ARE ALL VERY SIMILAR IN TIMING THE FRONT THROUGH ALL BUT THE FAR SOUTHEAST CFWA AS EARLY AS MIDDAY...AND THAT MAY BE TOO SLOW IF CONVECTION THURSDAY NIGHT PUSHES HAS ANY SAY. POINT IS...WITH CLOUDS LINGERING...AND FRONT ON THE MOVE...THE BEST CHANCE FOR ANY PRECIPITATION FRIDAY WILL BE EAST/SOUTHEAST CWFA. KEPT A SMALL RISK FOR FRIDAY NIGHT...IN CASE POST FRONTAL ELEVATED PRECIPITATION CAN FORM...WHICH IT OFTEN DOES FOR A TIME IN THESE SITUATIONS. THE WEEKEND LOOKS ADMIRABLE WEATHER WISE. ANOMALOUSLY DRY AIR IS FORECAST TO COME INTO THE CENTRAL PLAINS BEHIND COLD FRONT FRIDAY...DRIVEN BY GREAT LAKES REGION LOW PRESSURE. PWAT VALUES ARE FORECAST TO BE IN THE LOWER HALF OF CLIMATOLOGY VALUES. THOUGH DEWPOINTS MAY BE HELD UP SLIGHTLY WITH EVAPOTRANSPIRATION AND RECENT RAINFALL ISSUES...IT SHOULD STILL FEEL MUCH MORE PLEASANT WITH DEWPOINTS IN THE 50S FOR MOST AREAS. NEXT SHOT FOR A STORM OR TWO COULD COME MONDAY EVENING IN THE WESTERN ZONES...AS A STORM MAY FLOUNDER IN FROM THE HIGH PLAINS. LITTLE BETTER RISK OF STORMS POSSIBLE TUESDAY/WEDNESDAY...AS THE RIPPLE EFFECT RETURNS WITH A WEAK WAVE CUTTING THROUGH THE RIDGE. TEMPERATURES SHOULD GRADUALLY WARM A FEW DEGREES EACH BEGINNING SATURDAY. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ HEINLEIN ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HASTINGS NE 355 PM CDT WED JUN 25 2008 .SHORT TERM...FOR TONIGHT THROUGH THURSDAY NIGHT. LATEST WATER VAPOR IMAGERY REVEALS A FAIRLY ZONAL FLOW REGIME ACROSS THE NORTHERN HALF OF THE CONUS WITH SEVERAL SMALL BUT POTENT WAVES EMBEDDED WITHIN THIS UPPER FLOW PATTERN. ONE OF THESE WAVES IS CURRENTLY SLIDING OUT OF THE HIGH PLAINS WHILE A SECOND WAVE IS SEEN PUSHING INTO THE ROCKIES. RECENT OBJECTIVE SURFACE ANALYSIS SHOWS TWO BOUNDARIES OF INTEREST ACROSS THE AREA WITH A DIFFERENTIAL HEATING BOUNDARY STRETCHING FROM NEAR MCCOOK TO AROUND GRAND ISLAND WHILE WEAK SURFACE TROUGH IS SEEN STRETCHING FROM NORTHERN IOWA INTO NORTH CENTRAL NEBRASKA. LOOKING AT RUC ANALYSIS...ML CAPES OF 3000 TO AS HIGH AS 4500 J/KG ARE SEEN FROM NORTHERN KANSAS INTO CENTRAL NEBRASKA ALTHOUGH MOST OF THIS AREA CONTINUES TO HAVE MODEST TO STRONG INHIBITION. HOWEVER...WEAKER INHIBITION IS SHOWN ACROSS NORTH CENTRAL NEBRASKA AND AGAIN ACROSS NORTHWESTERN KANSAS. TAKING A LOOK AT VISIBLE SAT IMAGERY IN THESE WEAKER INHIBITION AREAS...A SMALL CLUSTER OF CU IS VISIBLE NEAR KGLD BUT LITTLE IS SHOWN ACROSS NORTH CENTRAL NEBRASKA. MAIN QUESTION AS THE AREA HEADS INTO THIS EVENING TO OVERNIGHT IS WHERE DEEP CONVECTION MAY DEVELOP. INITIAL PROBLEM WITH DEVELOPING DEEP CONVECTION ACROSS THE AREA LATE THIS AFTERNOON TO EARLY EVENING IS THAT FORCING FROM THE FIRST WAVE MOVING THROUGH THE REGION NOW...IS SHOWN TO SLIDE EAST OF THE FORECAST AREA BY EARLY EVENING. GIVEN THE TIMING OF THIS WAVE PRODUCING INCREASING MID LEVEL SUBSIDENCE ALONG WITH A LACK OF ANY CONVECTIVE DEVELOPMENT OVER THE REGION THIS AFTERNOON...CONFIDENCE IS LOW THAT DEEP CONVECTION WILL DEVELOP THROUGH EARLY EVENING. WILL OPT TO KEEP A SLIGHT CHANCE OVER MOST OF THE CWA BUT THIS MAY NEED TO BE REMOVED BY THE EVENING SHIFT IF NOTHING DEVELOPS. IF SOMETHING DOES DEVELOP...SEVERE THREAT LOOKS MARGINAL AS EFFECTIVE DEEP LAYER SHEAR WILL REMAIN WEAK AT 15 TO 25 KNOTS AT BEST. WILL KEEP MENTION OF SEVERE BUT WILL DECREASE MAX HAIL SIZE DOWN TO PENNY TO QUARTER SIZE. HOWEVER...AS THE EVENING PROGRESSES INTO THE OVERNIGHT HOURS A 30 TO 40 KT LLJ IS SHOWN TO NOSE INTO THE AREA WITH WHATEVER CONVECTION REMAINS ACROSS THE HIGH PLAINS SLIDING EAST INTO THE CWA. COVERAGE OF STORMS LOOKS SMALL...BUT WILL KEEP A SLIGHT CHANCE OVER MOST OF THE CWA THROUGH THE NIGHT. THURSDAY AFTERNOON INTO THURSDAY NIGHT IS THEN SHAPING UP TO BE AN ACTIVE TIME FRAME ACROSS THE REGION. A WEAK AREA OF LOW PRESSURE IS SHOWN BY THE MODELS TO SPIN UP OVER NORTH CENTRAL NEBRASKA WITH A WARM FRONT SEEN EXTENDING EAST ACROSS NORTHERN NEBRASKA WHILE A DRYLINE STRETCHES SOUTH ACROSS FAR WESTERN SECTIONS OF THE FORECAST AREA GENERALLY NEAR HIGHWAY 283. DEEP LOW LEVEL MOISTURE WILL BE AVAILABLE AHEAD OF THE DRYLINE AND ON EITHER SIDE OF THE WARM FRONT. THIS IS SHOWN TO PRODUCE ML CAPES OF 2000 TO 2500 J/KG NEAR THE DRYLINE AND 3000 TO 3500 J/KG NEAR THE WARM FRONT. A HEALTHY SHORT WAVE IS SHOWN TO RIDE OUT OF THE ROCKIES INTO THE PLAINS DURING THE AFTERNOON AND EXPECT THIS TO TRIGGER ISOLATED CONVECTIVE DEVELOPMENT ALONG THE DRYLINE AND MORE SCATTERED DEVELOPMENT JUST NORTH OF THE CWA NEAR THE WARM FRONT. SEVERE CONVECTION WISE...EFFECTIVE DEEP LAYER SHEAR WILL BE RATHER WEAK ALONG DRYLINE BY MID TO LATE AFTERNOON WITH VALUES OF 10 TO 25 KNTS AT BEST. THIS SHOULD KEEP CONVECTION ON THE WEAKER SIDE OVER THIS PORTION OF FORECAST AREA. HOWEVER...WITH SURFACE WINDS BACKING AROUND TO A MORE EASTERLY DIRECTION CLOSER TO THE WARM FRONT...EFFECTIVE DEEP LAYER SHEAR OF 25 TO NEAR 40 KNTS SHOULD SUPPORT GOOD CELL ORGANIZATION AND POSSIBLE ROTATION. TORNADO THREAT LOOKS MINIMAL BUT LARGE HAIL THREAT LOOKS POSSIBLE MAINLY NORTH OF HIGHWAY 92. TEMPERATURE WISE...A VERY WARM AFTERNOON LOOKS ON TAP WITH HIGHS RANGING FROM THE LOWER TO MID 90S NEAR ORD TO OSCEOLA...TO THE MID 90S TO AROUND 100 ACROSS NORTH CENTRAL KANSAS. .LONG TERM...12Z FRIDAY THROUGH WEDNESDAY. A COLD FRONT WILL BE ON TOP OF THE CWFA FRIDAY MORNING...AS MAY LEFTOVER SHOWERS AND DEBRIS CLOUDS FROM ANY THURSDAY NIGHT MCS ACTIVITY. THE MODELS ARE ALL VERY SIMILAR IN TIMING THE FRONT THROUGH ALL BUT THE FAR SOUTHEAST CFWA AS EARLY AS MIDDAY...AND THAT MAY BE TOO SLOW IF CONVECTION THURSDAY NIGHT PUSHES HAS ANY SAY. POINT IS...WITH CLOUDS LINGERING...AND FRONT ON THE MOVE...THE BEST CHANCE FOR ANY PRECIPITATION FRIDAY WILL BE EAST/SOUTHEAST CWFA. KEPT A SMALL RISK FOR FRIDAY NIGHT...IN CASE POST FRONTAL ELEVATED PRECIPITATION CAN FORM...WHICH IT OFTEN DOES FOR A TIME IN THESE SITUATIONS. THE WEEKEND LOOKS ADMIRABLE WEATHER WISE. ANOMALOUSLY DRY AIR IS FORECAST TO COME INTO THE CENTRAL PLAINS BEHIND COLD FRONT FRIDAY...DRIVEN BY GREAT LAKES REGION LOW PRESSURE. PWAT VALUES ARE FORECAST TO BE IN THE LOWER HALF OF CLIMATOLOGY VALUES. THOUGH DEWPOINTS MAY BE HELD UP SLIGHTLY WITH EVAPOTRANSPIRATION AND RECENT RAINFALL ISSUES...IT SHOULD STILL FEEL MUCH MORE PLEASANT WITH DEWPOINTS IN THE 50S FOR MOST AREAS. NEXT SHOT FOR A STORM OR TWO COULD COME MONDAY EVENING IN THE WESTERN ZONES...AS A STORM MAY FLOUNDER IN FROM THE HIGH PLAINS. LITTLE BETTER RISK OF STORMS POSSIBLE TUESDAY/WEDNESDAY...AS THE RIPPLE EFFECT RETURNS WITH A WEAK WAVE CUTTING THROUGH THE RIDGE. TEMPERATURES SHOULD GRADUALLY WARM A FEW DEGREES EACH BEGINNING SATURDAY. && .AVIATION...FOR THE 18Z KGRI TAF. VFR TO MVFR CONDITIONS ANTICIPATED FOR THE GRAND ISLAND TERMINAL THROUGH THE NEXT 24 HOURS. THE MAIN FORECAST CONCERN WILL REVOLVE AROUND A CHANCE OF SHOWERS AND THUNDERSTORMS LATE THIS AFTERNOON TO EARLY THIS EVENING. APPEARS COVERAGE OF STORMS WILL BE HIGH ENOUGH TO WARRANT A MENTION IN THE FORECAST FOR THE THE TERMINAL AREA. OTHERWISE...EXPECT THREAT FOR STORMS TO SLIDE SOUTH OF THE TERMINAL BY MID TO LATE EVENING WITH VFR CONDITIONS EXPECTED THROUGH THURSDAY MORNING. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 815 PM EDT THU JUN 26 2008 .SYNOPSIS... A WEAK FRONTAL BOUNDARY WILL BRING SCATTERED SHOWERS AND THUNDERSTORMS TONIGHT. THIS WILL BE FOLLOWED BY A PASSING HIGH PRESSURE SYSTEM THAT WILL BRING US RAIN FREE CONDITIONS TO MOST OF THE AREA FRIDAY. THE WEEKEND WILL THEN BECOME UNSETTLED AS A DEEPENING TROUGH OVER THE GREAT LAKES REGION WILL RESULT IN FREQUENT BOUTS OF SHOWERS AND THUNDERSTORMS. && .NEAR TERM /THROUGH FRIDAY/... CLOUDS LEFT OVER FROM THIS MORNING`S SHOWERS HAS KEPT THE AIR OVER NEW YORK STATE RELATIVELY STABLE COMPARED TO AREAS OVER THE CENTRAL GREAT LAKES AND OHIO VALLEY. THIS HAS PRECLUDED THE DEVELOPMENT OF ANY CONVECTION ACROSS OUR CWA...SO FAR THIS AFTERNOON. THE CLOUDS HAVE THINNED OUT NICELY ACROSS THE NIAGARA PENINSULA...BUT ANY CONVECTION THAT FIRES UP ACROSS THIS AREA LATER THIS AFTERNOON WILL HAVE TO FIGHT THE STABILIZING LAKE ERIE BREEZE. THEREFORE...DO NOT EXPECT ANY ORGANIZED CONVECTION TO TAKE PLACE ACROSS THE NIAGARA FRONTIER THROUGH THE EARLY EVENING. WE WILL HAVE TO MONITOR THE GENESEE VALLEY FOR THE POSSIBILITY OF CONVECTION LATER THIS AFTERNOON INTO THE EARLY EVENING. THIS AREA WILL STILL WARM UP A FEW MORE DEGREES AS THE CLOUDS THIN OUT UNDER THE INFLUENCE OF THE STRENGTHENING LAKE ERIE BREEZE. THE RUC SUGGESTS THAT CAPES MAY INCREASE A LITTLE ABOVE 1000 J/KG WITH LI`S LOWERING TO ABOUT -5. IF TEMPERATURES WARM UP A LITTLE MORE ACROSS THE SOUTHERN TIER...A FEW SHOWERS OR THUNDERSTORMS ARE POSSIBLE ACROSS THIS AREA AS WELL. OUR ATTENTION THEN TURNS TO THE MIDWEST COLD FRONT THAT IS HELPING TO GENERATE STRONG THUNDERSTORMS FROM LOWER LAKE HURON TO CENTRAL INDIANA INTO THE OHIO VALLEY. THIS FRONT IS FORECAST TO MOVE SLOWLY TO THE EAST AND DROP SOUTH ACROSS LAKE ONTARIO TONIGHT BEFORE STALLING OVER CENTRAL/SOUTHERN NEW YORK STATE ON FRIDAY. WILL LEAVE IN A CHANCE OF SHOWERS AND THUNDERSTORMS FOR TONIGHT AS THE FRONT INTERACTS WITH THE MOIST AIR AND SOMEWHAT UNSTABLE AIR THAT WILL STILL BE IN PLACE ACROSS THE AREA. THE ATMOSPHERE WILL BE SOMEWHAT MORE CAPPED ON FRIDAY...BUT WILL LEAVE IN A CHANCE OF SHOWERS AND THUNDERSTORMS ACROSS THE SOUTHERN TIER AND UPPER GENESEE VALLEY WHERE THE WARM UNSTABLE AIR WILL INTERACT WITH THE STALLED FRONT. IF THE FRONT STALLS FARTHER TO THE NORTH...WE MAY HAVE TO INCLUDE A CHANCE FOR SHOWERS/THUNDERSTORMS FOR MOST OF THE CWA. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... THE WEAK SURFACE RIDGE WILL SLIDE EAST OF THE AREA FRIDAY NIGHT AS A POTENT UPPER LEVEL SHORTWAVE OVER THE NORTHERN PLAINS WILL SETTLE ACROSS THE UPPER MIDWEST. A STRENGTHENING SOUTHWEST FLOW BETWEEN THESE TWO FEATURES WILL ADVECT INCREASED BOUNDARY LAYER MOISTURE ACROSS OUR REGION...AND WILL SET THE STAGE FOR SCATTERED SHOWERS AND THUNDERSTORMS. ON SATURDAY...THE CUTOFF SHORTWAVE WILL ROTATE ACROSS THE UPPER GREAT LAKES WHILE ITS ASSOCIATED COLD FRONT WILL PUSH ACROSS THE OHIO VALLEY TOWARDS OUR FORECAST AREA. INCREASING LARGE SCALE ASCENT AND LOW LEVEL CONVERGENCE WILL BRING A GOOD LIKELIHOOD OF CONVECTION DURING THIS TIME. PRECIPITABLE WATER VALUES NEARING 2 INCHES WILL BRING THE POTENTIAL FOR LOCALIZED HEAVY RAINFALL. THERE WILL ALSO BE A RISK FOR SEVERE WEATHER WITH INCREASINGLY STRONG WIND FIELDS ALOFT. MODEL CONSENSUS IS THAT THE COLD FRONT WILL WORK THROUGH THE AREA SATURDAY NIGHT CONTINUING THE LIKELIHOOD OF CONVECTION. BEHIND THE FRONT THERE WILL LIKELY BE A BREAK IN THE CONVECTIVE POTENTIAL... BUT WE SHOULD SEE ACTIVITY REDEVELOP SUNDAY AS THE COLD UPPER AIR LOW WORKS ACROSS THE AREA. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... THE MEDIUM RANGE PERIOD LOOKS TO BEGIN RATHER UNSETTLED AS A BROAD UPPER LEVEL TROUGH AND ITS CLOSED 500 MB CIRCULATION/COLD POOL ALOFT WORKS THROUGH THE GREAT LAKES REGION. THERE WILL BE GOOD CHANCES FOR CONVECTION THROUGH TUESDAY. FOR WEDNESDAY AND THURSDAY...THE UPPER LEVEL TROUGH AXIS WILL MOVE DOWNSTREAM WITH SURFACE RIDGE BUILDING IN FROM THE MID ATLANTIC STATES/TENNESSEE VALLEY. THIS PERIOD WILL HAVE THE BEST CHANCES FOR AN EXTENDED PERIOD OF DRY WEATHER. TEMPERATURES THROUGH EARLY NEXT WEEK LOOK TO BE AT OR BELOW NORMAL BUT SHOULD BE WARMING TO ABOVE NORMAL LEVELS BY THURSDAY. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... A LINE OF SHOWERS AND THUNDERSTORMS DIVING SOUTHEASTWARD ACROSS ONTARIO CANADA IS SHOWING SIGNS OF WEAKENING WITH THE LOSS OF DAYTIME HEATING. THE ACTIVITY IS AHEAD OF A WEAK COLD FRONT AND WILL BECOME MORE SPARSE AS THE NIGHT PROGRESSES. TWO AREAS OF CONCENTRATED SHOWERS AND THUNDERSTORMS ARE ACROSS THE NORTHEASTERN END OF LAKE ONTARIO AND ALSO ACROSS OHIO AND NORTHWESTERN PENNSYLVANIA. VFR TO MVFR CONDITIONS TONIGHT WITH THE EXCEPTION OF THE SOUTHERN TIER WHERE VISIBILITIES MAY LOWER INTO IFR CONDITIONS TOWARDS DAYBREAK. THE WEAKENING FRONT IS FORECAST TO STALL OVER SOUTHERN NEW YORK STATE FRIDAY. WITH MOIST AIR STILL IN PLACE ACROSS THE AREA DAYTIME HEATING WILL MAY STILL GENERATE A FEW -TSRA ALONG THE FRONT DURING THE AFTERNOON. THE BEST CHANCE FOR CONVECTION FRIDAY AFTERNOON WILL BE ACROSS THE SOUTHERN TIER AND UPPER GENESEE VALLEY. EXPECT CONDITIONS TO PRIMARILY REMAIN IN THE MVFR RANGE THROUGH A GOOD DEAL OF TOMORROW. OUTLOOK... SATURDAY...VFR. CHC SHWRS. SUNDAY THROUGH TUESDAY...VFR/MVFR. CHC TSTMS. && .MARINE... WHILE THERE WILL BE THE RISK OF SCATTERED THUNDERSTORMS OVER LAKES ERIE AND ONTARIO TONIGHT...NO WIND BASED MARINE HEADLINES WILL BE NECESSARY THROUGH AT LEAST FRIDAY. AN AREA OF LOW PRESSURE OVER SOUTHERN ONTARIO WILL PASS BY TO THE NORTH OF THE LAKES THIS EVENING...WITH MODERATE TO FRESH SOUTHWESTERLIES BEING PRODUCED OVER LAKE ERIE AS A RESULT. MEANWHILE...GENTLE TO MODERATE BREEZES WILL BE FOUND ON LAKE ONTARIO. A RIDGE WILL THEN CROSS THE EASTERN LAKES TONIGHT AND FRIDAY...WITH LIGHT TO GENTLE BREEZES PREDOMINATING. UNSETTLED CONDITIONS ARE THEN EXPECTED ACROSS BOTH LAKES FOR THE WEEKEND AS THE POTENTIAL FOR THUNDERSTORMS WILL MARKEDLY INCREASE. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...NONE. && $$ SYNOPSIS...TMA NEAR TERM...TJP SHORT TERM...TMA LONG TERM...TMA AVIATION...THOMAS/TJP MARINE...TMA ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 157 PM EDT THU JUN 26 2008 .SYNOPSIS... A STORM SYSTEM MOVING ACROSS LOWER CANADA, WILL DRAG A WEAK COLD FRONT ACROSS NY AND PA LATE THIS AFTERNOON. THIS FRONT COULD CAUSE SCATTERED THUNDERSTORMS TO FORM, WITH A FEW STRONG STORMS POSSIBLE. && .NEAR TERM /THROUGH TONIGHT/... UPDATED AT 1015 AM...-SHRA ASSCD WITH MCV PULLING OUT...AND FOCUS TURNS TO POTNL REDVLPMNT THIS AFTN. RUC PROFILES SHOW THE DVLPMNT OF A MID LVL CAPPING LAYER...A FEATURE WHICH IS EVIDENT IN THE UPSTREAM DTX AND APX SNDGS AND TAMDAR DATA. K INDICES FALL INTO THE M20S ACRS CNTRL NY THIS AFTN...NOT FVRBL FOR REDVLPMNT. XTNSV CLD CVR ACRS THE RGN...WITH EXTRAPOLATION OF BACKEDGE INTO THE FINGER LAKES AND CNTRL SRN TIER IN THE 19-22Z TIME FRAME...WHICH IS IN GOOD AGREEMENT WITH LAMP DATA. BEST POTNL MAY ACTUALLY BE THIS EVENING IN THE 00Z-06Z TIME FRAME...AS INFLUENCES FROM WEAK S/WV AND SFC TROF BEGIN TO ENCROACH ON NW ZONES...WHERE GREATEST INSTAB SHUD RESIDE DUE TO MORE LATE DAY SUNSHINE. COULD ALSO SEE SOME ACTIVITY LATE ACRS WRN AD CNTRL PA..WHICH COULD PSBLY AFFECT THE AVP AREA LATE TDA OR THIS EVNG. BOTTOM LINE IS THAT ANY POTNL REDVLPMNT...IF IT OCCURS...WILL BE VERY LATE. BELIEVE SLGT CHC TO LOW CHC POPS WILL COVER IT FOR THIS AFTN. PREV BLO... PULLED BACK ON POPS OVER NORTHERN HALF OF FA AS MCS REMNANTS WILL BE MORE SCATTERED IN THIS AREA. FOCUS TODAY IS ON SEVERE POTENTIAL DURING THE AFTERNOON HOURS. LATEST NAM SEEMS FAR TOO MOIST IN PUSHING AVP DEW POINT INTO THE UPPER 60S. BASED ON SFC PARCEL TRAJECTORIES FROM MI/OH, IT APPEARS MID 60S IS A REALISTIC RANGE FOR MUCH OF OUR FORECAST AREA. COMBINED WITH FORECAST MAXES OF 78F-82F, WE GET CAPES AROUND 1100-1400 J/KG AND LI`S OF -2C TO -3C. THESE VALUES ARE NOT NEARLY AS UNSTABLE AS INDICATED BY MODELS 24 HOURS AGO. ALSO, THE MODELS HAVE PULLED BACK ON THE MID LEVEL FLOW QUITE A BIT. WE ARE NOW LOOKING AT 30-35 KTS AT MID LEVELS, AS OPPOSED TO THE ORIGINALLY FORECAST 50 KTS. BIG DIFFERENCE, ESPECIALLY GIVEN LACK OF UL JET STREAK. THIS CUTS DOWN ON THE POTENTIAL FOR ORGANIZED CONVECTION. SO THIS EVENT NO LONGER APPEARS SIGNIFICANT. HOWEVER SEVERE POTENTIAL REMAINS, WITH FOCUS LIKELY TO BE INFLUENCED BY BOUNDARIES REMAINING FROM THIS MORNING`S CONVECTION. MAIN THREAT WILL BE FOR MARGINALLY SEVERE HAIL. FLOW ALOFT DOES NOT SEEM TO INDICATE STRONG WINDS WITHOUT A STRONG SQUALL LINE. MORE LIKELY WE WILL SEE SCATTERED, DISCRETE CELLS WITH A FEW PULSING TO SEVERE LEVELS. && .SHORT TERM /FRIDAY THROUGH SUNDAY/... THE FIRST PART OF THE WEEKEND DOES NOT LOOK NEARLY AS PESSIMISTIC. THUNDERSTORM REDEVELOPMENT IS POSSIBLE AGAIN LATE FRIDAY, WITH A FEW STRONG CELLS POSSIBLE. AS UPPER LOW DEVELOPS ON SATURDAY, MULTIPLE WAVES WILL ROTATE THROUGH NY AND PA. HOWEVER THE FORCING IS NOT PARTICULARLY STRONG ON ANY GIVEN WAVE. HAVE PULLED BACK POPS TO REFLECT SCATTERED CONVECTION ON SATURDAY, AND KEPT LIKELY WORDING IN FOR SATURDAY NIGHT. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... MED RANGE MODEL SOLUTIONS CONTINUE TO SHOW REASONABLY GOOD AGREEMENT FOR THIS TIME PERIOD. UNSETTLED AS CUTOFF LOW OVER MICHIGAN SLOWLY MOVES EAST AND FILLS...SO BY END OF NEXT WEEK MAY GET A DRY WARM DAY. SFC COLD FRONT ON COAST SUN NGT INTO MONDAY WITH CUTOFF WELL WEST SO A RELATIVE LULL. SECONDARY COLD FRONT AND UL TROF TUESDAY. SLOW IMPROVEMENT WED TO THU AS UL TROF MOVES INTO NEW ENGLAND AND SFC HIGH BUILDS INTO OHIO VALLEY. MOST LIKELY TIME FOR SHOWERS WILL BE AFTERNOONS EARLY IN THE WEEK WITH DAYTIME HEATING CAUSING SHOWERS WITH COLD AIR ALOFT. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... MVFR/VFR CIGS AND VFR VSBYS ATTM. CIGS WILL SCATTER AND LIFT BY 21Z AS DRIZZLE AND MOISTURE HEADS SE. A SHORT WAVE AND SFC TROF COULD STILL SET OFF A FEW SHRA/TS LATE TODAY. AFTER MIDNIGHT LIGHT FOG PREDICTED SO MVFR VSBYS AND CIGS MOST PLACES. VFR DURING THE DAY FRIDAY. WEST WIND AT 5 TO 10 KTS BECOMING LIGHT AND VARIABLE TONIGHT THEN BACK TO WEST AT 5 TO 10 KTS FRIDAY AFTER 12Z. OUTLOOK... FRI NITE THRU TUE...AREAS OF MVFR IN TSRA/SHRA...ESPECIALLY SAT NIGHT AND SUNDAY. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DJP NEAR TERM... SHORT TERM...DJP LONG TERM...TAC AVIATION...TAC ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 747 AM EDT THU JUN 26 2008 .SYNOPSIS... A WARM FRONT WILL PUSH THROUGH PENNSYLVANIA EARLY TODAY. A SLOW MOVING COLD FRONT WILL LIKELY MOVE THROUGH THE REGION LATE IN THE WEEKEND. AN UPPER LEVEL TROUGH OF LOW PRESSURE WILL LIKELY BE OVER THE AREA EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... DYING MCS MOVING INTO CENTRAL PA EARLY THIS AM. HAVE RAISED POPS SIGNIFICANTLY OVR MUCH OF THE REGION EARLY THIS MORNING BASED ON RADAR TRENDS. LATEST RUC13 AND SREF DATA SUGGEST THIS WEAKENING AREA OF SHWRS...AND PERHAPS A RUMBLE OF THUNDER...WILL PUSH EAST OF THE REGION BY ARND 15Z WITH PASSAGE OF LL JET. IN WAKE OF MCS...WARMER AND MORE HUMID AIRMASS OVERSPREADS THE REGION LATER TODAY...AS SFC WARM FRONT PUSHES NORTH OF PA. EARLY CLOUDS SHOULD GIVE WAY TO BRIGHTENING SKIES BY MIDDAY...RESULTING IN SREF CAPES NR 2000 J/KG BY AFTN. ALTHOUGH NEARLY ALL OF CENTRAL PA IS UNDER A SLIGHT RISK FOR SVR WX THIS AFTN...LATEST ENS DATA SUGGESTS NORTHERN PA IS UNDER THE GREATEST RISK...AS CORE OF STRONGEST MID LVL WINDS FCST TO PASS OVR UPSTATE NY. FURTHER SOUTH...SREF 0-6KM SHEAR VALUES BLW 20KTS SUGGEST A MUCH LOWER CHC FOR ORGANIZED SVR WX ACROSS SOUTHERN PA. HIGHEST /CHC/ POPS THIS AFTN WILL BE PLACED OVR THE ALLEGHENY HIGHLANDS...WHERE ELEVATED HEAT SOURCE/TOPOGRAPHIC FORCING MOST LIKELY TO INITIATE CONVECTION. 850 TEMPS ARND 18C SUGGEST HIGHS ACROSS THE LOWER SUSQ VALLEY COULD HIT 90F TDY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... SCT EVENING CONVECTION SHOULD DWINDLE AFTER SUNSET THIS EVENING. WEAK SHORTWAVE PASSING THRU SOUTHERN ONTARIO/QUEBEC WILL PUSH A DYING COLD FRONT INTO NORTHERN PA. ACROSS SOUTHERN PA...DIURNAL HEATING OF MOIST/UNSTABLE AIRMASS SHOULD YIELD SCT AFTN PULSE TYPE CONVECTION ON FRIDAY. SREF 850 TEMPS SUPPORT HIGHS ARND 90F IN THE VALLEYS SOUTH OF I-80. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... BETTER PROBABILITIES FOR SHOWERS AND T-STORMS...SOME POSSIBLY SVR...STATEWIDE ON SATURDAY AS A SHARP SLOW-MOVING COLD FRONT APPROACHES THE REGION AHEAD OF DIGGING UPPER LVL TROF OVR THE WESTERN GRT LKS. FRONT GRADUALLY CROSSES AREA SAT NITE/SUNDAY...AS UPPER-LVL TROF CLOSES OFF OVER NORTHERN GRT LKS. WILL CARRY SHWRS AND T-STORMS INTO SUNDAY...ESPECIALLY ACROSS EASTERN PA. MEDIUM-RANGE MODELS PARK UPPER-LVL TROF OVER THE NORTHEASTERN UNITED STATES EARLY NEXT WEEK...RESULTING IN RELATIVELY COOL CONDS. GIVEN COLD TEMPS ALOFT...CAN/T RULE OUT SCT DIURNAL CONVECTION...ESPECIALLY ACROSS THE HIGHER TERRAIN. UPPER TROF LIKELY TO LIFT OUT BY MIDWEEK...RESULTING IN FAIR AND WARMER CONDS. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... LEFTOVER SHOWERS FROM COMPLEX THAT MOVED EAST FROM OHIO OVERNIGHT WILL DIMINISH IN COVERAGE BY MID MORNING AS THE SYSTEM SLIDES INTO THE EASTERN PART OF THE STATE. MVFR CIGS AND VSBYS IN FOG AND LOW CLOUDS RESULTING FROM THE PCPN WILL CONTINUE THRU LATE MORNING AS WELL. VFR FLYING TO RETURN BY THE AFTN WITH SCT- BKN CU. LATE DAY CLEARING MAY LEAD TO SOME ISOLD SHRA/TSRA ESP ACROSS THE NRN TIER CLOSE TO A DIFFUSE FNTL BNDRY. WEST TO EAST ZONAL PATTERN WILL KEEP ACTIVE WX THRU FIRST HALF OF WEEKEND. PERIODS OF DRY/WET WX FRI-SUN AS MODELS HINT AT PRODUCING A QUASI-STATIONARY BNDRY FROM SOUTHERN MO ARCHING NE TOWARDS DELMARVA. WHICH WOULD SUPPORT THINKING WITH CHC/S OF SHRA/TSRA EACH OF THE NEXT SEVERAL DAYS. MID LVL SHORTWAVE AND ASSOCIATED COLD FRONT SLIDES INTO GRT LKS SUN EVE. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...FITZGERALD NEAR TERM...FITZGERALD SHORT TERM...FITZGERALD LONG TERM...FITZGERALD/RXR AVIATION...GARTNER/STEINBUGL pa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 859 PM CDT WED JUN 25 2008 .UPDATE... SCT TSRA...SVR AT TIMES...ARE MOVING INTO FAR SW SD ATTM...ASSOCIATED WITH AN ADVANCING WARM FRONT/SFC TROF LIFTING INTO THE WRN SD. MSAS SHOWS SFC HIGH PRESSURE SITTING OVER THE ERN DAKOTAS...AND MOISTURE DEPRIVED KABR 00Z SOUNDING INDICATES THAT NOTHING SHOULD LIFT THIS FAR NE OVERNIGHT. THE LATEST NAM12 DOES SHOW STRONG UPPER LEVEL DIVERGENCE SKIRTING ALONG OUR SRN COUNTIES TONIGHT. WITH WATCH THAT HAS BEEN ISSUED THROUGH 09Z FOR THE FAR SW COUNTIES...DID ADD MENTION OF SEVERE TO WORDING FOR THOSE COUNTIES OVERNIGHT. OTW REMAINDER OF ZONES LOOKED GOOD AND NO EDITING REQUIRED. UPDATED AVIATION DISCUSSION BELOW. && .PREV DISCUSSION... .SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW WEAK UPPER LEVEL RIDGING ACROSS THE WESTERN HIGH PLAINS. SKIES ARE MOSTLY CLEAR ACROSS THE CWA WITH INCREASING CLOUDS OVER WYOMING AS A WEAK DISTURBANCE IS MOVING THROUGH THAT AREA. THIS SYSTEM IS EXPECTED TO SLIDE ACROSS THE NORTHERN PLAINS OVERNIGHT AND BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS TO MAINLY THE SOUTHERN CWA. LLJ SETS UP OVERNIGHT ACROSS WESTERN SOUTH DAKOTA AND EXPECT THIS IS WHERE ANY ACTIVITY WILL BEGIN. MODELS AGREE FAIRLY WELL IN SHOWING SOME FORM OF WEAK MESOSCALE SYSTEM MOVING ACROSS THE SOUTHERN PORTION OF THE STATE OVERNIGHT ALONG NOSE OF LLJ. DIFFERENCES SHOW UP IN JUST HOW FAR NORTH COMPLEX WILL DEVELOP...AND HOW LONG IT LASTS INTO THURSDAY...IF AT ALL. FOR NOW HAVE KEPT LOW CHANCE POPS ACROSS THE SOUTHEASTERN CWA FOR THURSDAY TO ACCOUNT FOR ANY ACTIVITY THAT PERSISTS THROUGH THE FIRST HALF OF THE DAY. FOCUS THEN SHIFTS TO LATE THURSDAY AND ESPECIALLY THURSDAY NIGHT. LOTS OF THINGS TO CONSIDER WITH SVR POTENTIAL AND MAX HIGHS. IF THUNDERSTORM COMPLEX PANS OUT AND MOVES ACROSS THE STATE THURSDAY MORNING...DEBRIS CLOUD COVER AND RAIN COOLED AIR WILL PROBABLY PREVENT HIGHS FROM REACHING CURRENT FORECAST. CLOUD COVER COULD ALSO SUPPRESS INSTABILITY ACROSS EAST CENTRAL SOUTH DAKOTA. BUT...STILL EXPECTING THIS COMPLEX TO BE EAST OF THE AREA BY TOMORROW AFTERNOON SO THERE SHOULD STILL BE ENOUGH TIME FOR INSTABILITY RECOVERY. THERE WILL PROBABLY ALSO BE OLD OUTFLOW BOUNDARIES TO CONTEND WITH DURING THE DAY TOMORROW WHICH MAY PROVIDE FOCUS FOR CONVECTION LATER IN THE AFTERNOON. MODELS SHOWING BEST PRECIP CHANCES ACROSS THE CWA OVERNIGHT IN ASSOCIATION WITH THE LLJ. SVR PARAMETERS RATHER SUPPORTIVE OF STRONG CONVECTION...ESPECIALLY ACROSS THE SOUTHERN PORTION OF THE CWA. SYSTEM EXITS THE AREA FRIDAY AND HAVE LEFT SMALL CHANCE POPS ACROSS THE NORTHEAST ON THE BACK SIDE OF THE LOW. POSSIBILITY EXISTS TO SEE A FEW WRAP AROUND INSTABILITY SHOWERS ACROSS THE EXTREME NORTHEASTERN PORTION OF THE AREA. .LONG TERM...SATURDAY THROUGH WEDNESDAY GOOD AGREEMENT WITH THE MODELS AND GFS ENSEMBLES THROUGH THE LONG TERM. THE PERIOD BEGINS WITH A LARGE UPPER LOW/TROUGH JUST OFF TO OUR EAST SLOWLY BUILDING ACROSS THE EASTERN US THROUGH MONDAY WHILE A SHARP 50H RIDGE ACROSS THE WESTERN US MOVES SLOWLY EAST TOWARDS OUR REGION. SATURDAY SHOULD HAVE BELOW NORMAL TEMPERATURES AS COOL AIR CONTINUES TO POUR ACROSS THE REGION BEHIND THE EXITING SURFACE LOW PRESSURE AREA. CURRENT FORECAST TEMPERATURES MAY HAVE TO BE LOWERED EVEN MORE. ALSO...MAY SEE SOME CAA CU AND ISOLD/SCT -SHRAS ACROSS NORTHEAST SD AND WEST CENTRAL MN DURING THE DAY AND EARLY EVENING HOURS ON SATURDAY. OTHERWISE...MOST OF THE EXTENDED LOOKS DRY AS THE UPPER LEVEL RIDGE OUT WEST BUILDS SLOWLY INTO THE REGION AND FLATTENS OUT SOME BY THE MIDDLE OF THE WEEK. EXPECT MOSTLY CLEAR SKIES DURING THIS TIME WITH A WARM UP AS HEIGHTS INCREASE. SHOULD HAVE QUITE A BIT OF UPPER 80S AND LOWER 90S BY MONDAY AND TUESDAY ACROSS THE CWA. INDICATIONS ARE THAT THE RIDGE WILL BREAK DOWN SOME BY TUESDAY NIGHT AND WEDNESDAY WITH A SHORT WAVE COMING INTO THE REGION. THUS...HAVE IN CHANCES OF TSRAS DURING THIS TIME. && .AVIATION... VFR CONDS EXPECTED THROUGH 18Z FOR ALL TERMINAL SITES. SOME ISOLD/SCT TSRA MAY DEVELOP AND MOVE SOUTH OF THE KPIR TERMINAL...CLOSER TO I-90...AFT 06Z...WITH LITTLE IMPACT THOUGH AT THE KPIR TERMINAL. LOOK FOR INCREASING WINDS AFT 15Z FOR ALL TERMINAL SITES AS WELL. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...HINTZ SHORT TERM...TMT LONG TERM...MOHR AVIATION...HINTZ WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 333 PM CDT WED JUN 25 2008 .SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW WEAK UPPER LEVEL RIDGING ACROSS THE WESTERN HIGH PLAINS. SKIES ARE MOSTLY CLEAR ACROSS THE CWA WITH INCREASING CLOUDS OVER WYOMING AS A WEAK DISTURBANCE IS MOVING THROUGH THAT AREA. THIS SYSTEM IS EXPECTED TO SLIDE ACROSS THE NORTHERN PLAINS OVERNIGHT AND BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS TO MAINLY THE SOUTHERN CWA. LLJ SETS UP OVERNIGHT ACROSS WESTERN SOUTH DAKOTA AND EXPECT THIS IS WHERE ANY ACTIVITY WILL BEGIN. MODELS AGREE FAIRLY WELL IN SHOWING SOME FORM OF WEAK MESOSCALE SYSTEM MOVING ACROSS THE SOUTHERN PORTION OF THE STATE OVERNIGHT ALONG NOSE OF LLJ. DIFFERENCES SHOW UP IN JUST HOW FAR NORTH COMPLEX WILL DEVELOP...AND HOW LONG IT LASTS INTO THURSDAY...IF AT ALL. FOR NOW HAVE KEPT LOW CHANCE POPS ACROSS THE SOUTHEASTERN CWA FOR THURSDAY TO ACCOUNT FOR ANY ACTIVITY THAT PERSISTS THROUGH THE FIRST HALF OF THE DAY. FOCUS THEN SHIFTS TO LATE THURSDAY AND ESPECIALLY THURSDAY NIGHT. LOTS OF THINGS TO CONSIDER WITH SVR POTENTIAL AND MAX HIGHS. IF THUNDERSTORM COMPLEX PANS OUT AND MOVES ACROSS THE STATE THURSDAY MORNING...DEBRIS CLOUD COVER AND RAIN COOLED AIR WILL PROBABLY PREVENT HIGHS FROM REACHING CURRENT FORECAST. CLOUD COVER COULD ALSO SUPPRESS INSTABILITY ACROSS EAST CENTRAL SOUTH DAKOTA. BUT...STILL EXPECTING THIS COMPLEX TO BE EAST OF THE AREA BY TOMORROW AFTERNOON SO THERE SHOULD STILL BE ENOUGH TIME FOR INSTABILITY RECOVERY. THERE WILL PROBABLY ALSO BE OLD OUTFLOW BOUNDARIES TO CONTEND WITH DURING THE DAY TOMORROW WHICH MAY PROVIDE FOCUS FOR CONVECTION LATER IN THE AFTERNOON. MODELS SHOWING BEST PRECIP CHANCES ACROSS THE CWA OVERNIGHT IN ASSOCIATION WITH THE LLJ. SVR PARAMETERS RATHER SUPPORTIVE OF STRONG CONVECTION...ESPECIALLY ACROSS THE SOUTHERN PORTION OF THE CWA. SYSTEM EXITS THE AREA FRIDAY AND HAVE LEFT SMALL CHANCE POPS ACROSS THE NORTHEAST ON THE BACK SIDE OF THE LOW. POSSIBILITY EXISTS TO SEE A FEW WRAP AROUND INSTABILITY SHOWERS ACROSS THE EXTREME NORTHEASTERN PORTION OF THE AREA. .LONG TERM...SATURDAY THROUGH WEDNESDAY GOOD AGREEMENT WITH THE MODELS AND GFS ENSEMBLES THROUGH THE LONG TERM. THE PERIOD BEGINS WITH A LARGE UPPER LOW/TROUGH JUST OFF TO OUR EAST SLOWLY BUILDING ACROSS THE EASTERN US THROUGH MONDAY WHILE A SHARP 50H RIDGE ACROSS THE WESTERN US MOVES SLOWLY EAST TOWARDS OUR REGION. SATURDAY SHOULD HAVE BELOW NORMAL TEMPERATURES AS COOL AIR CONTINUES TO POUR ACROSS THE REGION BEHIND THE EXITING SURFACE LOW PRESSURE AREA. CURRENT FORECAST TEMPERATURES MAY HAVE TO BE LOWERED EVEN MORE. ALSO...MAY SEE SOME CAA CU AND ISOLD/SCT -SHRAS ACROSS NORTHEAST SD AND WEST CENTRAL MN DURING THE DAY AND EARLY EVENING HOURS ON SATURDAY. OTHERWISE...MOST OF THE EXTENDED LOOKS DRY AS THE UPPER LEVEL RIDGE OUT WEST BUILDS SLOWLY INTO THE REGION AND FLATTENS OUT SOME BY THE MIDDLE OF THE WEEK. EXPECT MOSTLY CLEAR SKIES DURING THIS TIME WITH A WARM UP AS HEIGHTS INCREASE. SHOULD HAVE QUITE A BIT OF UPPER 80S AND LOWER 90S BY MONDAY AND TUESDAY ACROSS THE CWA. INDICATIONS ARE THAT THE RIDGE WILL BREAK DOWN SOME BY TUESDAY NIGHT AND WEDNESDAY WITH A SHORT WAVE COMING INTO THE REGION. THUS...HAVE IN CHANCES OF TSRAS DURING THIS TIME. && .AVIATION... VFR SKIES ARE EXPECTED THROUGH THE DAY...NIGHT AND MORNING THURSDAY WITH ONLY SOME SCT MID AND HIGH LEVEL CLOUDS AOA 8000 FEET. WILL HAVE TO WATCH THE PIR AND ATY AREAS TONIGHT AND EARLY THURSDAY FOR POSSIBLE THUNDERSTORM DEVELOPMENT. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ SHORT TERM...TMT LONG TERM...MOHR AVIATION...MOHR WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE AMARILLO TX 1126 PM CDT WED JUN 25 2008 .AVIATION... VFR CONDITIONS WILL PREVAIL AT ALL THREE TAF SITES THROUGH THURSDAY EVENING. NORTHWESTERLY FLOW ALOFT MAY BRING SOME CONVECTION INTO THE PANHANDLES THURSDAY AFTERNOON AND EVENING...HOWEVER DECIDED TO LEAVE OUT OF TAF PACKAGE FOR NOW AS CONFIDENCE LOW. CONVECTION MAY NOT AFFECT ANY OF TAF SITES SIMILAR TO THIS EVENING. WILL LET LATER SHIFTS INTRODUCE CONVECTION AS NEEDED. OTHERWISE...SOUTHERLY WINDS WILL INCREASE THURSDAY INTO THE 15 TO 25 KNOT RANGE. SCHNEIDER && .PREV DISCUSSION... /ISSUED 950 PM CDT WED JUN 25 2008/ UPDATE... CONVECTION DISSIPATING ACROSS THE REGION. APPEARS THE THREAT FOR STORMS IS DIMINISHING FOR THE PANHANDLES. RUC AND NAM DO SUGGEST THAT AN ISOLATED STORM MAY STILL DEVELOP OVERNIGHT. SO LOWERED POPS TO SLIGHT CHANCE THROUGH 12Z. JJB PREV DISCUSSION... /ISSUED 621 PM CDT WED JUN 25 2008/ AVIATION... CONVECTION EXPECTED TO AFFECT MAILY THE GUYMON AND DALHART TAF SITES THIS EVENING...AND MAY POSSIBLY AFFECT THE AMARILLO TAF SITE LATER THIS EVENING IF THEY CONTINUE TO HOLD TOGETHER AFTER SUNSET. OTHERWISE...SOUTH TO SOUTHWEST WINDS AROUND 10 TO 15 KNOTS TONIGHT WILL INCREASE THURSDAY MORNING TO 15 TO 25 KNOTS THROUGH THURSDAY AFTERNOON. VFR CONDITIONS WILL PERSIST WITH ONLY FEW TO SCATTERED CUMULUS AND SCATTERED TO BROKEN HIGH CLOUDS EXPECTED. SCHNEIDER PREV DISCUSSION... /ISSUED 224 PM CDT WED JUN 25 2008/ DISCUSSION... THUNDERSTORMS HAVE DEVELOPED EARLY THIS AFTERNOON ACROSS THE MOUNTAINS OF NEW NEW MEXICO...SOUTHERN COLORADO AND ALONG A SURFACE TROUGH THROUGH NORTHEAST NEW MEXICO. THESE STORMS SHOULD AGAIN MOVE SOUTHEAST LATE THIS AFTERNOON AND TONIGHT ACROSS MUCH OF THE PANHANDLES IN A NORTHWEST FLOW ALOFT. DO NOT SEE MUCH CHANGE IN THE PATTERN THROUGH THIS FORECAST. RIDGING WILL CONTINUE ACROSS THE SOUTHERN AND CENTRAL ROCKIES AND UPPER LEVEL TROUGHING WILL BE FOUND ACROSS THE EASTERN HALF OF THE U.S. A STRONG UPPER LEVEL LOW PRESSURE SYSTEM WILL DIVE SOUTHEAST INTO NORTHERN MINNESOTA BY FRIDAY WHICH WILL HELP TO DRIVE A COLD FRONT THROUGH THE PANHANDLES BY EARLY SATURDAY MORNING. THIS FRONT WILL BE ANOTHER FOCUS FOR THUNDERSTORM DEVELOPMENT BESIDES THE MOUNTAINS...SO CHANCES FOR STORMS MAY BE A LITTLE ENHANCED. THE NORTHWEST FLOW ACROSS THE PANHANDLES WILL INCREASE SOME AS THE UPPER LEVEL TROUGH GETS CARVED OUT OVER THE EASTERN HALF OF THE U.S. AND THE RIDGE STAYS PUT OVER THE ROCKIES. THIS WILL KEEP THE THREAT OF AFTERNOON AND NIGHTTIME THUNDERSTORMS GOING ACROSS THE PANHANDLES INTO MID NEXT WEEK. LOW LEVEL MOISTURE AND THE INSTABILITY WILL NOT BE GOING ANYWHERE THROUGH THIS FORECAST...SO SEVERE THUNDERSTORMS AND LOCALLY HEAVY RAINFALL WILL CONTINUE TO BE THREATS. FIRE WEATHER... LIGHTNING WILL BE A THREAT FOR STARTING WILDFIRES. BUT...WITH THE MOISTURE IN PLACE AND LIGHTER WINDS THE OVERALL WILDFIRE DANGER WILL BE LOW THROUGH THIS FORECAST. && .AMA WATCHES/WARNINGS/ADVISORIES... TX...NONE. OK...NONE. && $$ 11/14 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE AMARILLO TX 950 PM CDT WED JUN 25 2008 .UPDATE... CONVECTION DISSIPATING ACROSS THE REGION. APPEARS THE THREAT FOR STORMS IS DIMINISHING FOR THE PANHANDLES. RUC AND NAM DO SUGGEST THAT AN ISOLATED STORM MAY STILL DEVELOP OVERNIGHT. SO LOWERED POPS TO SLIGHT CHANCE THROUGH 12Z. JJB && .PREV DISCUSSION... /ISSUED 621 PM CDT WED JUN 25 2008/ AVIATION... CONVECTION EXPECTED TO AFFECT MAILY THE GUYMON AND DALHART TAF SITES THIS EVENING...AND MAY POSSIBLY AFFECT THE AMARILLO TAF SITE LATER THIS EVENING IF THEY CONTINUE TO HOLD TOGETHER AFTER SUNSET. OTHERWISE...SOUTH TO SOUTHWEST WINDS AROUND 10 TO 15 KNOTS TONIGHT WILL INCREASE THURSDAY MORNING TO 15 TO 25 KNOTS THROUGH THURSDAY AFTERNOON. VFR CONDITIONS WILL PERSIST WITH ONLY FEW TO SCATTERED CUMULUS AND SCATTERED TO BROKEN HIGH CLOUDS EXPECTED. SCHNEIDER PREV DISCUSSION... /ISSUED 224 PM CDT WED JUN 25 2008/ DISCUSSION... THUNDERSTORMS HAVE DEVELOPED EARLY THIS AFTERNOON ACROSS THE MOUNTAINS OF NEW NEW MEXICO...SOUTHERN COLORADO AND ALONG A SURFACE TROUGH THROUGH NORTHEAST NEW MEXICO. THESE STORMS SHOULD AGAIN MOVE SOUTHEAST LATE THIS AFTERNOON AND TONIGHT ACROSS MUCH OF THE PANHANDLES IN A NORTHWEST FLOW ALOFT. DO NOT SEE MUCH CHANGE IN THE PATTERN THROUGH THIS FORECAST. RIDGING WILL CONTINUE ACROSS THE SOUTHERN AND CENTRAL ROCKIES AND UPPER LEVEL TROUGHING WILL BE FOUND ACROSS THE EASTERN HALF OF THE U.S. A STRONG UPPER LEVEL LOW PRESSURE SYSTEM WILL DIVE SOUTHEAST INTO NORTHERN MINNESOTA BY FRIDAY WHICH WILL HELP TO DRIVE A COLD FRONT THROUGH THE PANHANDLES BY EARLY SATURDAY MORNING. THIS FRONT WILL BE ANOTHER FOCUS FOR THUNDERSTORM DEVELOPMENT BESIDES THE MOUNTAINS...SO CHANCES FOR STORMS MAY BE A LITTLE ENHANCED. THE NORTHWEST FLOW ACROSS THE PANHANDLES WILL INCREASE SOME AS THE UPPER LEVEL TROUGH GETS CARVED OUT OVER THE EASTERN HALF OF THE U.S. AND THE RIDGE STAYS PUT OVER THE ROCKIES. THIS WILL KEEP THE THREAT OF AFTERNOON AND NIGHTTIME THUNDERSTORMS GOING ACROSS THE PANHANDLES INTO MID NEXT WEEK. LOW LEVEL MOISTURE AND THE INSTABILITY WILL NOT BE GOING ANYWHERE THROUGH THIS FORECAST...SO SEVERE THUNDERSTORMS AND LOCALLY HEAVY RAINFALL WILL CONTINUE TO BE THREATS. FIRE WEATHER... LIGHTNING WILL BE A THREAT FOR STARTING WILDFIRES. BUT...WITH THE MOISTURE IN PLACE AND LIGHTER WINDS THE OVERALL WILDFIRE DANGER WILL BE LOW THROUGH THIS FORECAST. && .AMA WATCHES/WARNINGS/ADVISORIES... TX...NONE. OK...NONE. && $$ 11/14 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 321 PM CDT THU JUN 26 2008 FORECAST FOCUS ON SEVERE WEATHER CHANCES FOR FRIDAY. NEAR-TERM...TONIGHT. DEALING WITH MAINLY CI BLOW OFF AT THE MOMENT. COMPLEX ACRS IA INTO MO SAPPING UP THE MOIST/INFLOW/INSTAB. ISODROSOTHERM ANALYSIS SHOWS A LITTLE BUBBLE OF DRIER AIR HAS WORKED INTO SRN WI WITH THE REAL GOOD JUICE OFF TO THE WEST. THINKING IS THAT REDEVELOPMENT WILL TAKE PLACE LATER TNGT TO OUR WEST WITH CHANCES INCREASING ACRS THE CWA LATER TNGT. FOR NOW WILL LEAN TOWARDS THE QPF TRENDS OF THE NAM/RUC AND NGM WHICH KEEPS US LARGELY RAIN FREE THRU 6Z. .SHORT TERM...KEY TO FRIDAY SEVERE TIMING AND PLACEMENT WILL BE DEPENDENT ON OVERNIGHT WARM AIR ADVECTION CONVECTION AND RESULTANT OUTFLOW BOUNDARIES. WILL LEAN TOWARD NAM FOR DETAILS AS SPURIOUS 500MB CONVECTIVE VORTICITY MAXIMA ON GFS AFFECTING LAYERS BELOW...MAKING IT AN OUTLIER. CWA IN FAVORED REGION TO THE LEFT OF STRONGEST 850 MB WINDS BETWEEN 18Z-00Z SAT. SUFFICIENT INSTABILITY WITH ML CAPES OF 1500-2000 J/KG...EVEN AFTER LOWERING SOMEWHAT GENEROUS SFC DEW POINTS. DEEP LAYER SHEAR OF 25 TO 30 KTS ENOUGH TO ORGANIZE STORMS. WILL LEAVE LIKELY WORDING FOR NOW...BUT ALL OF THE CWA SHOULD SEE SCATTERED TO WIDESPREAD CONVECTION FRIDAY AFTERNOON AND EVENING. AS FOR RAIN FROM THE STORMS IMPACTING SATURATED SOILS AND SWOLLEN RIVERS...PRECIPITABLE WATERS INCREASE TO 1.54 INCHES...BUT MESO- BETA ELEMENTS MOVING AT 15 TO 20 KNOTS DURING MOST FAVORED TIME. WILL RE-ISSUE ESF FOR NOW AS IT WILL TAKE ONLY 1/4 TO 1/2 INCH OF RAIN IN AN HOUR OR LESS TO CAUSE SOME STREET FLOODING PROBLEMS BUT NOT ENOUGH CLARITY TO TARGET ANY GIVEN AREA FOR A WATCH AT THIS TIME. UPPER LOW SETTLES IN OVER REGION FOR THE WEEKEND. SIMILAR TO LAST WEEK...500 MB TEMPERATURES IN THE -15C TO -18C RANGE WILL LEAD TO STEEP MID LVL LAPSE RATES AND ENOUGH INSTABILITY FOR ISOLATED AFTERNOON AND EARLY EVENING THUNDERSTORM DEVELOPMENT BOTH SATURDAY AND SUNDAY. POSSIBILITY AGAIN FOR SMALL HAIL AND GUSTY WINDS WITH INVERTED V SOUNDINGS. MONDAY...TIMING OF UPPER LOW EXITING WESTERN GREAT LAKES WILL BE KEY TO EARLY NEXT WEEK FORECAST. OPERATIONAL FORECASTS ALL TAKE UPPER LOW AND ASSOCIATED COLD POOL TO AROUND THE STRAITS OF MACKINAW BY 00Z MONDAY...AND OVER...OR NORTH OF... LAKE HURON BY 12Z MONDAY. WILL KEEP SLIGHT CHANCE FOR SUNDAY NIGHT AND HAVE DRY WITH RIDGING BUILDING INTO REGION FOR MONDAY INTO WEDNESDAY. .LONG TERM...QUIET WEATHER MONDAY THROUGH WEDNESDAY MORNING...WITH NEAR NORMAL TEMPERATURES. NORTHERLY SFC WIND TURNS NE ALONG THE LAKE...SO EARLY AFTERNOON HIGHS THEN FALLING TEMPS MONDAY. WEAK GRADIENT TUESDAY BRINGS SIMILAR TEMP SCENARIO. NEXT PRECIPITATION CHANCE COMES WED AFTERNOON/EVENING WITH WARM AIR ADVECTION REGIME SETTING UP AHEAD OF NEXT 500MB TROF. ML CAPES REACH 1000-1500 J/KG IN NW HALF OF ON FAVORED ECMWF BY 00Z SO WILL BRING CHANCES THERE IN THE AFTERNOON...AND CWA-WIDE WED NIGHT. SLOW MOVEMENT OF SFC TROF THRU REGION BRINGS POTENTIAL FOR A FEW ROUNDS OF SHOWERS AND STORMS INTO FRIDAY MORNING. && .AVIATION...VFR THROUGH PERIOD AS ANY FORCING MECHANISMS FOR THUNDERSTORMS REMAIN VERY SUBTLE UNDER WEAK FLOW. LLJ REMAINS PARKED UPSTREAM OF THE CWA AND EXPECT REGENERATING THUNDERSTORMS TO FIRE ACROSS NW IA/SW MN INTO TONIGHT. COULD SEE THOSE STORMS ROLL IN LATER TONIGHT...BUT THERE IS STILL UNCERTAINTY AS TO THAT EVOLUTION. HOWEVER WILL HINT AT SOME THUNDER IN THE TAFS LATER TNGT INTO FRI MORNING. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && $$ SHORT/LONG TERM...09 AVIATION/MARINE...10 wi AREA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE LA CROSSE WI 745 PM CDT WED JUN 25 2008 .UPDATE... QUITE AN AIRMASS DIFFERENCE BETWEEN SEVERAL DIFFERENT WEAK FRONTAL ZONES ACROSS THE AREA THIS EVENING. WEAK NE/SW ORIENTED COLD FRONT /A REFLECTION OF DEPARTING ONTARIO CANADA HEIGHT FALLS/ IS SHIFTING STEADILY INTO THE FORECAST AREA. 26.00Z KMPX RAOB WAS A JAW-DROPPER IN THE MAIN SUBSIDENCE REGION BEHIND THE FRONT...WITH PWATS CUT IN HALF /1.2 TO 0.6 INCH/ AND RATHER DEEP NWLY FLOW. CONTRAST THIS...TO AIRMASS SOUTH OF WEAK/DIFFUSE WARM FRONTAL STRUCTURE FROM WHERE IT INTERSECTS COLD FRONT IN NWRN IA...DOWN ALONG I-80 TOWARD MUSCATINE IOWA....WHERE DEWPOINTS IN THE UPPER 70S AND SBCAPES TOWARD 5000 J/KG ARE COMMON. NO SURPRISE...WITH THE ADDITION OF SUBTLE MID LEVEL CIRCULATION /MCV/ HITTING THE INSTABILITY GRADIENT IN PLACE FROM SRN IA INTO NRN IA THAT EXPLOSIVE DEEP CONVECTION HAS OCCURRED...ESPECIALLY ALONG WARM FRONTAL STRUCTURE OVER CNTL IA...WHERE GOLFBALL HAIL HAS BEEN OBSERVED. SHORT RANGE LOCAL WRF-BASED 13KM RUC MODEL...AGREES WHOLEHEARTEDLY WITH 26.15Z SREF PROBS THAT THIS COMPLEX OF SCT STORMS IN CNTL IA WILL SINK SLOWLY SOUTHEAST AS IT MATURES THIS EVENING. EARLIER E-W BAND OF CONVECTION HANCOCK/CERRO GORDO COUNTY HAS FORMED A COLD POOL IS NOW PROPAGATING SOUTH/EAST WITH MCV TAKING MAIN ECHOES JUST SOUTHWEST OF CCY/OLZ AREAS. MAY GET QUITE MESSY IN CNTL IA TONIGHT GIVEN MERGING MCS CLUSTERS AND HEAVY RAIN. GIVEN TRENDS IN 26.18Z WRF/GFS OF SIGNIFICANT DRYING IN THE SOUNDINGS NORTH OF I-90...EXPECT MUCH OF RAIN CHANCES REST OF NIGHT TO BE CONFINED TO THE FAR SOUTH. COULD STILL POP A SHOWER IN THE FAR NORTH WITH COLD FRONT...BUT CUMULUS FIELD IS LOSING ORGANIZATION. UPDATED FORECAST/HAZ WEATHER OUTLOOK IS OUT. BINAU && .PREV DISCUSSION... /ISSUED 325 PM CDT WED JUN 25 2008/ SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT FORECAST CONCERNS THIS PACKAGE CONTINUE TO BE CONVECTION POTENTIAL AND RAIN AMOUNTS. DATA ANALYSIS THIS AFTERNOON HAD AN AREA OF LOW PRESSURE OVER NORTHERN MN WITH A TROUGH EXTENDING SOUTH/SOUTHWEST THROUGH WESTERN IA INTO EASTERN NE. MEANWHILE...WATER VAPOR/VIS SATELLITE IMAGERY SHOWED A REMNANT MVC MEANDERING EASTWARD ACROSS NORTHWEST IA. A FEW LIGHT SHRA SHOWING UP ON THE RADAR MOSAIC ASSOCIATED WITH THIS FEATURE...BUT NO GROUND REPORTS THUS FAR. VIS SATELLITE ALSO SHOWING SCATTERED CU FIELD IN WEAK SURFACE/MOISTURE CONVERGENCE AHEAD OF THE TROUGH ACROSS MN. TEMPERATURES MORE INDICATIVE OF SUMMER THIS AFTERNOON WITH READINGS IN THE UPPER 70S TO MID 80S WITH DEW POINTS IN THE 60S. CURRENTLY SPC MESOANALYSIS TOOL SHOWING 100MB ML CAPE IN THE 500-1500J/KG RANGE ACROSS THE AREA WITH ALMOST NIL CIN. 25.12Z GFS/NAM STILL IN FAIRLY GOOD AGREEMENT THOUGH THE PERIOD WITH SPEED AND INTENSITY OF SYNOPTIC SCALE FEATURES AFFECTING THE AREA THROUGH THE PERIOD. DIFFERENCES ARISE IN PLACEMENT AND AMOUNT OF RAINFALL. CONTINUED TO TAKE A BLEND APPROACH AS FAR AS FINAL QPF PLACEMENT/AMOUNT WAS CONCERNED. GFS/NAM/SREF ALL HINTING AT SOME CONVECTION ALONG THE TROUGH AS IT MOVES FROM MN THROUGH WI THIS EVENING. WATER VAPOR IMAGERY WAS INDICATING SOME DECENT SUBSIDENCE/DRYING BEHIND THIS TROUGH AS IT SLIDES SOUTHEAST THROUGH THE AREA THIS EVENING. SO EXPECT PRECIPITATION CHANCES TO BE CONFINED ACROSS THE FAR SOUTH WHERE TROUGH WILL LAY UP AFTER MIDNIGHT. MODELS IN GOOD AGREEMENT THAT BULK OF 925-850MB MOISTURE TRANSPORT TONIGHT WILL BE SOUTH OF I-80...SO RESULTANT BULK OF SHRA/TS SHOULD REMAIN SOUTH OF THE AREA. BOTTOM LINE...MAINTAINED SMALL CHANCES OF SHRA/TS ACROSS THE NORTH THIS EVENING...THEN CONFINED SHRA/TS CHANCES TO FAR SOUTH WHERE THE TROUGH WILL LAY UP COMBINED WITH NORTHERN PERIPHERY OF MOISTURE TRANSPORT. NOT TOO CONCERNED WITH SEVERE POTENTIAL. BEST OPPORTUNITY WOULD BE ACROSS THE NORTH THIS EVENING WHERE SLIGHTLY BETTER BULK SHEAR AND CAPE IN THE 1000-1500J/KG WILL EXIST. AFTER MIDNIGHT ACROSS THE SOUTH...ML CAPE DIMINISHES INTO THE 500-1000J/KG RANGE...PRETTY MINIMAL FOR SEVERE THREAT. FOR THURSDAY...THE TROUGH STARTS TO LIFT NORTHWARD BACK INTO THE AREA AS SURFACE CYCLOGENESIS TAKES PLACE OVER THE HIGH PLAINS. BETTER 925-850MB TRANSPORT ADVECTS INTO/OVER THE FRONTAL BOUNDARY DURING THE AFTERNOON HOURS FOR INCREASING SHRA/TS CHANCES. BETTER CHANCES WILL EXIST ACROSS THE SOUTHWEST WITH DIMINISHING CHANCES TO THE NORTHEAST. NAM INDICATING ML CAPE IN THE 1500-2000J/KG RANGE ALONG THE FRONTAL BOUNDARY. HOWEVER...FAVORABLE BULK SHEAR REMAINS WEST OF THE AREA. SO...EXPECT SCATTERED SHRA/TS ALONG THE FRONTAL BOUNDARY WITH MOISTURE CONVERGENCE...BUT SEVERE THREAT SEEMS MITIGATED BY LACK OF GOOD SHEAR. CANNOT HOWEVER RULE OUT SOME SEVERE HAIL WITH STRONGER UPDRAFTS DURING THE AFTERNOON. FOR THURSDAY NIGHT THROUGH FRIDAY MORNING...LOW PRESSURE MOVING OUT OF THE PLAINS WILL LIFT THE WARM FRONT THROUGH THE AREA. MODELS INDICATING MODERATE AMOUNT OF MOISTURE TRANSPORT INTO THE FRONT AS IT MOVES THROUGH THE AREA WITH 0-3KM MUCAPE INCREASING INTO THE 2500-3000J/KG RANGE AND 0-3KM BULK SHEAR INCREASING INTO THE 25 TO 35KT RANGE. SO...EXPECTING A GOOD CHANCE TO LIKELIHOOD OF SHRA/TS ACTIVITY WITH PERHAPS A FEW SEVERE THUNDERSTORMS CONTAINING LARGE HAIL/DAMAGING WINDS THURSDAY NIGHT/FRIDAY MORNING. IN ADDITION...WITH PRECIPITABLE WATER VALUES HOVERING IN THE 1.5 TO 2.0 INCH RANGE...HEAVY POCKETS OF RAINFALL IS ALSO LIKELY. HEAVY RAINFALL THREAT IS DETAILED IN THE HYDROLOGY SECTION BELOW. THE LOW CONTINUES TO DEEPEN AND MOVE ALONG THE CANADA/MN BORDER FRIDAY AFTERNOON. THIS PUSHES A COLD FRONT INTO THE AREA. THE QUESTION BECOMES ON HOW FAST THE ATMOSPHERE CAN RECOVER FROM THURSDAY NIGHT/FRIDAY MORNING CONVECTION. BOTH NAM AND GFS INDICATING COLD FRONT WILL BE ON TOP OF US BY NOON WITH MUCAPE VALUES INCREASING INTO THE 2500-4500J/KG RANGE. BULK SHEAR ALSO APPEARS SUFFICIENT FOR SEVERE THUNDERSTORM PRODUCTION. HELICITY IN THE LOWEST 3KM ALSO POINTS TOWARD THE POSSIBILITY OF A TORNADO OR TWO. THE FRONT AND BULK OF SHRA TS ACTIVITY APPEARS LIKE IT WILL MOVE EAST/SOUTHEAST OF THE AREA BY FRIDAY EVENING. FOR SATURDAY THROUGH SATURDAY NIGHT...THE LOW WILL BECOME VERTICALLY STACKED OVER SOUTHWEST ONTARIO WITH COLD POOL CIRCULATING OVERHEAD. THIS PRODUCES STEEP LAPSE RATES AND SHRA/TS CHANCES ACROSS THE AREA THROUGH THIS PERIOD. LONG TERM...SUNDAY THROUGH WEDNESDAY 25.00Z ECMWF/25.06Z GFS REMAIN IN GOOD AGREEMENT THROUGH MONDAY WITH UPPER LOW SLOWLY SHIFTING EAST OF THE AREA AS A RIDGE BUILD IN FROM THE PLAINS. CONTINUED SHRA/ISOLD T CHANCES THROUGH SUNDAY NIGHT AS THE AREA REMAINS IN WESTERN PERIPHERY OF COLD POOL ALOFT. TEMPERATURES WILL REMAIN COOLER THAN NORMAL WITH SCATTERED PRECIPITATION AND MIXING OF 5-6C AIR FROM 850MB. WITH HEIGHTS BUILDING ON MONDAY AND SUBSIDENCE...IT SHOULD BE DRY WITH HIGHS REBOUNDING BACK TO NEAR SEASONAL NORMALS IN THE UPPER 70S TO LOWER/MIDDLE 80S. TEMPERATURES WILL CONTINUE TO WARM A COUPLE MORE DEGREES TUESDAY AS THE RIDGE BUILDS OVER THE AREA. BY WEDNESDAY...BOTH THE GFS/ECMWF HINT AT A MID-LEVEL SHORTWAVE TROUGH/SURFACE COLD FRONT WILL ROUND THE TOP OF THE RIDGE AND AFFECT THE AREA TUESDAY NIGHT THROUGH WEDNESDAY WITH A CHANCE OF SHRA/TS. AVIATION... A WEAK COLD FRONT OVER CENTRAL MINNESOTA WILL MOVE EAST ACROSS BOTH THE RST AND LSE TAF SITES LATE THIS AFTERNOON AND EVENING. A WEAK MESOSCALE VORTEX OVER NORTHEAST NEBRASKA AND SOUTHEAST SOUTH DAKOTA WILL MOVE ALONG THE COLD FRONT AND INTO NORTHERN IOWA THIS EVENING AND TONIGHT. SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP ALONG THE FRONT AND ASSOCIATED MESOSCALE VORTEX THIS AFTERNOON. DUE TO CONCERNS WITH TIMING OF THE FRONT AND SCATTER IN NATURE OF CONVECTION HAVE KEPT VCSH AT BOTH RST AND LSE AFTER 22-23Z. BOTH THE LATEST 25.12Z NAM AND GFS INDICATE SURFACE COLD FRONT TO MOVE INTO NORTHERN IOWA AFTER 06Z THURSDAY. WITH THE BEST FORCING AND MOISTURE CONVERGENCE WELL SOUTH OF TAF SITES...HAVE INTRODUCE DRY CONDITIONS AND SCATTERED CLOUDS AFTER 09Z. HYDROLOGY... WILL CONTINUE TO KEEP AN EYE OUT FOR FLOODING POTENTIAL MAINLY FROM THURSDAY THROUGH FRIDAY WITH PRECIPITABLE WATER VALUES INCREASING INTO 1.5 TO 2 INCH RANGE AND BETTER THUNDERSTORM ENVIRONMENT TO FOCUS HEAVIER RAINS. A WARM FRONT MOVING SLOWLY NORTHWARD THROUGH THE AREA THURSDAY THROUGH FRIDAY WILL PROVIDE THIS ENVIRONMENT. HOWEVER...OVERALL MODEL CONSENSUS IS THAT 1 TO 2 INCHES OF RAINFALL WILL BE POSSIBLE FROM TONIGHT THROUGH FRIDAY...WITH THE BULK OF THIS FALLING IN THE THURSDAY TROUGH FRIDAY TIME FRAME. BELIEVE SOME FOCUSED 2 TO 3 INCH AMOUNTS ARE POSSIBLE...BUT EXACT AREA AND TIMING IS STILL HARD TO PINPOINT AT THIS TIME. RIGHT NO IT APPEARS AREAS ALONG AND SOUTH OF I-90 WILL BE MORE SUSCEPTIBLE FOR HEAVIER RAINFALL POTENTIAL. BULK OF THIS AREA HAS HAD SOME DRYING OVER THE PAST FEW DAYS WITH SOILS NOW CAPABLE OF ABSORBING 1 TO 2 INCHES BEFORE RUNOFF OCCURS INTO STREAMS AND CREEKS. HOWEVER...IF INTENSE ENOUGH...RAINFALL COULD PRODUCE RUNOFF PROBLEMS QUICKER IN STEEPER TERRAIN AREAS. AS A RESULT WILL RE-ISSUE AN ESF TO ADDRESS THE HEAVY RAIN THREAT AND POTENTIAL FOR RUNOFF PROBLEMS. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ 01/01 wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 252 PM CDT WED JUN 25 2008 .SHORT TERM... MCV ACROSS LOWER MI SHIFTING AWAY FROM SRN WI/N IL. RUC ANALYSIS DOES SHOW WEAK VORT LOBE HOWEVER SUBSIDENCE FIELD LEFT BEHIND BY DEPARTING VORT SEEMS TO BE PUTTING THE KIBOSH ON VERTICAL DEVELOPMENT. WITH SURFACE FRONT APPROACHING LATER TONIGHT MAY BE ENUF INSTABILITY COMBINED WITH WEAKENING SUBSIDENCE TO ALLOW SOMETHING TO FIRE. ALSO WATCHING INTERESTING LOOKING CLOUD MASS ACRS NRN IA WORKING EWD. NAM IS DRY AND GFS IS WET...ESPECIALLY OVER THE SRN CWA...SO WILL TRIM GFS MOS POPS...MUCH LIKE LAST NIGHT. APPROACHING FRONT SHOULD STALL OVER FAR SOUTHERN WISCONSIN OR NORTHERN ILLINOIS THURSDAY MORNING. NAM SHOWS CAPES AROUND 1700 J/KG THURSDAY AFTERNOON. HOWEVER MID LEVELS RATHER DRY...AND LOW LEVEL MOISTURE IS SHALLOW. ALSO NO TRIGGER WITH WEAK LOW LEVEL FLOW. MODELS DON`T GENERATE ANY SIGNIFICANT PRECIPITATION THURSDAY. CRAS MODEL ALSO SHOWS NO DEEP CONVECTION UNTIL POSSIBLY LATE THURSDAY AFTERNOON OVER THE FAR SOUTH...CLOSE TO THE EXPECTED SURFACE BOUNDARY. 850 MB FLOW INCREASES ACROSS NORTHEAST IOWA...WITH SOME CONVERGENCE AS WARM FRONT PUSHES NORTH. THIS WOULD BRING A POTENTIAL OF A MCS. SOME HEAVY RAINFALL POSSIBLE GIVEN PRECIPITABLE WATER VALUES INCREASING TO AROUND 1.70 INCHES. BEST CHANCE FOR SEVERE WEATHER AND HEAVY RAINFALL APPEARS TO BE FRIDAY AFTERNOON AND EVENING...AS A STRONG SHORTWAVE APPROACHES FROM THE NORTHWEST. UPPER DIFLUENCE ALONG WITH MODERATE INSTABILITY AND INCREASING SEVERE PARAMETERS. EHI VALUES RISE TO 2.75 WITH BULK RICHARDSON NUMBERS AROUND 20. THUS SOME SUPER CELL POTENTIAL AHEAD OF THE APPROACHING COLD FRONT. THIS SCENARIO COULD PRODUCE SOME TORNADO THREAT PROVIDING THE CAP BREAKS DURING OR LATE AFTERNOON. .LONG TERM... ECMWF SHOWED A DEEP SHORTWAVE TROUGH WITH A CUTOFF LOW PUSHING THROUGH THE GREAT LAKES REGION SATURDAY AND SUNDAY. WITH THE COLD AIR IN THE UPPER LEVELS...THE RESULTANT AFTERNOON INSTABILITY SHOULD PRODUCE SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS. BOTH THE ECMWF AND GFS KEEPS THE UPPER TROUGH OVER THE EASTERN GREAT LAKES REGION MONDAY...CLOSE ENOUGH FOR A CHANCE OF AFTERNOON SHOWERS. UPPER LEVEL RIDGING BEHIND THE SHORTWAVE WITH NORTHWEST FLOW OVER THE UPPER MISSISSIPPI VALLEY SHOULD THEN BRING QUIET WEATHER TO THE AREA. THE ECMWF IS A BIT MORE PROGRESSIVE WITH A SHORTWAVE OVER THE WEST BY MID WEEK...BUT THIS WOULD BECOME AN ISSUE MORE FOR WEDNESDAY NIGHT AND THURSDAY. && .AVIATION... WILL GO MAINLY VFR THIS PERIOD. MVFR CU FIELD EXPECTED TO DISSIPATE. MAY SEE SOME HAZE/LIGHT FOG AS WELL NOW THAT WE HAVE SOME HIGHER DEWS OVERTAKING THE CWA. CONFIDENCE IN CONVECTION LOW AT THE MOMENT SO WILL OPT TO LEAVE OUT OF TAFS...HOWEVER APPCH FRONT LATER IN THE NIGHT MAY SERVE AS A FOCUS. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && $$ SHORT/LONG TERM...06/HENTZ AVIATION/MARINE...10/COLLAR wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 331 AM CDT FRI JUN 27 2008 .DISCUSSION... ISSUED 330 AM CDT FRI JUN 27 2008 FORECAST CHALLENGES CONTINUE WITH SHORT RANGE MODELS NOT HANDLING MCS ACTIVITY VERY WELL DURING THE PAST FEW DAYS. BROKEN BAND OF CONVECTION QUICKLY FIRED UP DURING THE PAST HOUR FROM SE IA INTO WEST CENTRAL IL NEAR THE MS RIVER AND LIFTING ENE. RUC MODEL HINTED AT THIS SCENERIO THOUGH DEVELOPED QPF TOO QUICKLY. WILL ADDRESS CONVECTION CHANCES ALONG WITH SLIGHT RISK OF SEVERE STORMS THROUGH SAT AS COLD FRONT SLIDES SE THROUGH IL LATER TONIGHT AND INTO SAT. 08Z/3 AM SURFACE MAP SHOWS A FRONTAL BOUNDARY OVER SOUTHERN LOWER MI/WI/MN. MATURE MCS WAS OVER CENTRAL/EASTERN KY WITH WEAKER MCS OVER SW MN/EASTERN SD AND FAR NW IA. NEWLY DEVELOPED BROKEN LINE OF CONVECTION FROM SE IA INTO WEST CENTRAL IL AND ANOTHER AREA OF CONVECTION OVER SW IL SW OF MOUNT VERNON. CONVECTION IN WESTERN IL APPEARS TO BE TIED TO SW LOW LEVEL JET/WARM FRONT. MOIST DEWPOINTS IN THE MID 60S WHILE TEMPS IN THE UPPER 60S AND LOWER 70S WITH LIGHT SOUTH WINDS. ALOFT UPPER LEVEL HIGH PRESSURE WAS SPRAWLED ACROSS THE SOUTHERN STATES WITH UPPER LEVEL TROF/LOW OVER CANADA. SHORT WAVE TROF WAS OVER THE MID/UPPER MS VALLEY AND ALSO IN THE DAKOTAS. 553 DM 500 MB LOW WAS ALONG THE SOUTHERN ALBERTA AND SASKETCHEWAN BORDER AND DIGGING INTO THE NORTHERN PLAINS. SHORT TERM...TODAY THROUGH TUESDAY. INCREASED CHANCES OF SHOWERS AND THUNDERSTORMS TODAY TO LIKELY ALONG AND NW OF I-55 ESPECIALLY THIS MORNING WITH BROKEN LINE OF CONVECTION MOVING ENE INTO THE IL RIVER VALLEY. SOME OF THESE THUNDERSTORMS COULD BE STRONG ALONG WITH BRIEF HEAVY RAINS AND FREQUENT LIGHTNING. HAVE 30 TO 40% CHANCE OF SHOWERS AND THUNDERSTORMS ACORSS EAST CENTRAL AND SE IL TODAY. MOST SHORT RANGE MODELS SHOW A SHORT WAVE/MCV MOVING INTO IL FROM NE KS THIS AFTERNOON. THIS MOVING INTO AN UNSTABLE AIR MASS WITH PEAK HEATING THIS AFTERNOON SHOULD GENERATE SCATTERED CONVECTION. TONED DOWN HIGHS A BIT WITH MORE CLOUD COVER AND CONVECTION EXPECTED TODAY THAN EARLIER THOUGHT AS WAS THE CASE NW OF I-70 YESTERDAY. STILL VERY WARM AND HUMID WITH HIGHS IN THE UPPER 80S IN CENTRAL IL AND LOWER 90S SE IL FROM I-70 SE WITH DEWPOINTS AROUND 70F. COULD BE ISOLATED STRONG TO SEVERE THUNDERSTORMS THIS AFTERNOON WITH UNSTABLE AIR MASS AND ARRIVING MCV. BEST CHANCES OF CONVECTION WITH POSSIBLE SEVERE THUNDERSTORMS WILL ARRIVE TONIGHT AS A COLD FRONT MOVES SE TOWARD THE IA/IL BORDER BY MIDNIGHT AND TO I-55 BY 12Z/SAT. THIS DUE TO UPPER LEVEL TROF AMPLIFYING/DIGGING INTO THE UPPER MID WEST FROM SOUTHERN ALBERTA/SASKETCHEWAN. INCREASED POPS TO 80% NW OF I-70 TONIGHT. SPC CONTINUES SLIGHT RISK OF SEVERE STORMS ACROSS CENTRAL/SE IL TONIGHT. BEST CHANCE OF SEVERE STORMS WEST OF I-57 WITH 15 TO 30% SEVERE WIND GUSTS AND HAIL AND ISOLATED TORNADOES (2%). COLD FRONT COLLIDING WITH A VERY UNSTABLE AIR MASS WITH CAPES PEAKING FROM 2000 TO 3000 J/KG WEST OF I-57. BUT LIMITNG FACTORS FOR WIDESPREAD SEVERE STORMS IS UPPER LEVEL DYNAMICS AND BEST WIND FIELDS ARE NORTH OF CENTRAL IL. ALSO MORNING CONVECTION COULD LIMIT HEATING AND DESTABILIZATION OF ATMOSPHERE THIS AFTERNOON. ALSO CONCERN FOR HEAVY RAIN WITH PRECIPITABLE WATER VALUES OF 1.75 TO 2 INCHES. HAVE 0.75 TO 1.5 INCHES OF RAIN ACROSS AREA THROUGH TONIGHT WITH HIGHEST AMOUNTS OVER THE IL RIVER VALLEY. DID NOT ISSUE A FLASH FLOOD WATCH YET SINCE FLASH FLOOD GUIDANCE VALUES ARE 1.75 TO 2.5 INCHES PER HOUR...2 TO 3 INCHES PER 3 HOURS AND 2.5 TO 3.5 INCHES IN 6 HOURS. BUT ISOLATED AREAS IN THE IL RIVER VALLEY COULD SEE LOCAL 1.5 TO 3 INCH AMOUNTS TODAY AND TONIGHT SIMILAR TO WHAT HAPPENED TUE NIGHT. COLD FRONT SLIDE SE THROUGH SE IL SAT AND CONTINUES GOOD CHANCE OF CONVECTION IN EASTERN IL ESPECIALLY SAT MORNING AND MAINLY IN SE IL SAT AFTERNOON. SPC HAS SLIGHT RISK OF SEVERE STORMS SAT SE OF A CHAMPAIGN TO TAYLORVILLE LINE WITH BEST CHANCE SE OF A DANVILLE TO EFFINGHAM LINE WHERE CAPES PEAK FROM 1500 TO 2000 J/KG. A DRY WEDGE WORKS INTO CENTRAL IL DURING SAT BEHIND THE COLD FRONT WITH DEWPOINTS DROPPING THROUGH THE 60S WITH WEST BREEZES. COOLER HIGHS IN THE LOWER 80S CENTRAL IL AND MID 80S SE IL. SMALL CHANCE OF CONVECTION OVER SE IL UNTIL SUNSET SAT EVENING...OTHERWISE MOST AREAS WILL BE DRY SAT NIGHT. MODELS CONSISTENT IN BRINGING STRONG UPPER LEVEL LOW PRESSURE INTO NORTHERN MI SUNDAY AND TRENDING A BIT CLOUDIER...COOLER...BREEZIER AND BETTER CHANCES OF SHOWERS AND ISOLATED THUNDERSTORMS ESPECIALLY SUNDAY AFTERNOON UNTIL SUNSET SUNDAY EVENING. COOLED HIGHS A BIT INTO THE MID TO UPPER 70S AND INCREASED WNW WINDS TO BREEZIER LEVELS OF 15 TO 25 MPH. UPPER LEVEL LOW DRIFTS SLOWLY EAST INTO THE EASTERN GREAT LAKES BY TUE TAKING ITS SHOWERS EAST OF IL EARLY NEXT WORK WEEK. AREAS ALONG THE INDIANA BORDER COULD STILL SEE A RISK OF SHOWERS AND ISOLATED THUNDERSTORMS MON AFTERNOON. LONG TERM...TUESDAY NIGHT THROUGH THURSDAY. NO CHANGES MADE TO EXTENDED FORECAST WITH DRY WEATHER AND GRADUALLY MODIFYING TEMPERATURES TO NEAR OR A BIT ABOVE NORMAL AS UPPER LEVEL HEIGHTS RISE OVER IL BY MID WEEK. HIGHS WARM BACK INTO THE MID TO UPPER 80S WED AND THU AS HUMIDITY LEVELS INCREASE AS WELL. ECMWF SHOWING COLD FRONT AND QPF MOVING INTO IL THU. THIS IS A DAY SOONER THAN THE GFS AND DGEX MODELS WHEN IT BRINGS THIS INTO IL ON FRI. NO CHANGES MADE YET SINCE AWAITING BETTER MODEL AGREEMENT THAT FAR OUT. HUETTL && .AVIATION... ISSUED 1201 AM CDT FRI JUN 27 2008 LGT/VRBL LOW LEVEL FLOW WILL PREVAIL THROUGH 12Z FRI. ALL CLOUDS WILL BE WELL WITHIN THE VFR RANGE...HOWEVER SOME VSBYS MAY REACH 4-5SM IN FOG/HAZE 09Z-13Z. A SLGT CHC THAT TSTMS COULD DVLP/MOVE E ACROSS IA INTO PIA/SPI 09Z-12Z FRI...BUT CHC IS TOO SMALL FOR TAF MENTION. DEBRIS FROM STORMS OUT WEST WILL LIKELY DRIFT THROUGH THE AREA 13Z-16Z RESULTING IN SCT-BKN STRATOCU AROUND 4K FT. COLD FRONT IS FORECAST TO MOVE INTO ERN IA BY 00Z SAT AND PROGRESS TO NWRN IL BY 06Z. SCT TSTMS PSBL LATE AFTN/EARLY EVENING PIA/SPI AHEAD OF THE FRONT...WITH CONVECTION BECOMING MORE WIDESPREAD AND SPREADING EWD THROUGH 06Z SAT. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 210 AM EDT FRI JUN 27 2008 .AVIATION... ONGOING MENTION OF MVFR FOG AT KFWA APPEARS ON TRACK ACCORDING TO CONDITIONAL CLIMATOLOGY...HOWEVER...ADJUSTED TIMING SLIGHTLY. KEPT THUNDER MENTION LATE IN THE TAF PERIOD AS LOW LEVEL FLOW INCREASES THIS AFTERNOON. BOUNDARY FROM CONVECTION HAD PUSHED WELL TO THE SOUTH AND WAS STILL ACTIVE WITH STORMS. BELIEVE BEST CHANCE FOR STORMS IS AFTER 22Z AS AN UPPER LEVEL SYSTEM FROM THE WEST APPROACHES. && .PREV DISCUSSION... /ISSUED 733 PM EDT THU JUN 26 2008/ UPDATE... TSRA ACTIVITY WHICH FORMED AHEAD OF MCV MOVG ESE ACROSS NRN INDIANA HAS MAINLY MOVED EAST OF THE AREA THIS EVE. STRATIFORM RAIN IN COMMA HEAD OF THIS VORTEX AFFECTING FWA ATTM SHOULD MOVE EAST OF THE TERMINAL BY ISSUANCE TIME. ISOLATED TSRA CONTG ALONG OUTFLOW BOUNDARIES AND POCKETS OF REMAINING INSTABILITY. VISIBLE LOOP SHOWING SKIES CLEARING NW OF MCV WITH WATER VAPOR LOOP ALSO INDICATING SUBSIDENCE ACROSS NW INDIANA/NE IL...THOUGH A FEW SHRA/TSRA ALSO HAVE DEVELOPED WITHIN THE CLEARING ZONE. THIS CONVECTIVE ACTIVITY TOO ISOLATED TO MENTION IN TAFS...BUT WILL KEEP AN ISOLATED STORM MENTIONED IN ZONES OVERNIGHT AS WK SHRTWV MOVG EAST FROM IA MAY HELP TRIGGER SOME CONVECTION BY LATE TONIGHT. WITH LIGHT WINDS AND SKIES GENERALLY BECOMING MAINLY CLEAR TONIGHT FOG SHOULD DEVELOP...ESPECIALLY IN AREAS WHICH HAD RAIN THIS AFTN WHICH WAS MOST OF THE CWA EXCEPT FAR NW. WILL ADD PATCHY FOG MENTION TO GRIDS/ZONES AND GO WITH MVFR VSBYS AT FWA FOR LATE TONIGHT AND EARLY FRIDAY. LOW PRESSURE EXPECTED TO MOVE EAST INTO THE UPPER MS VALLEY ON FRI WITH ASSOCIATED WARM FRONT LIFTING NE INTO NRN INDIANA. THIS SHOULD HELP TRIGGER TSRA IN THE AFTN AS DAYTIME HEATING SHOULD ONCE AGAIN RESULT IN VERY UNSTABLE CONDITIONS BY THAT TIME. PREV DISCUSSION... NEAR TERM... MAIN CONCERN IN NEAR TERM IS WITH TSTMS. MCV MOVG ACROSS NW INDIANA THIS AFTN. LAPS SFC BASED CAPES UP TO 4KJ/KG AHEAD OF THIS FEATURE. SFC TROF ALSO EVIDENT FM ERN MI SW TO WEST CENTRAL INDIANA. SCT TSTMS HAVE BEEN FORMING ALONG THIS BOUNDARY THIS AFTN. WITH WK SHEAR AND VERY MOIST/UNSTABLE ENVIRONMENT...STORMS WILL BE MARGINALLY SEVERE WITH GUSTY WINDS... VERY HEAVY RAIN.... AND SOME HAIL. EXPECT THIS ACTIVITY TO PERSIST INTO THE EVE ALONG SFC TROF AND SUBSEQUENT TSTM OUTFLOW BOUNDARIES SO HAVE CONTD WITH SCT POPS THROUGH 00Z SE WITH A CHC NW. FOR THE EVE HOURS INHERITED LIKELY POPS ACROSS THE NORTHERN COUNTIES. GFS WITH SUPPORT FROM RUC13 INDICATING AN AT LEAST PARTIALLY CONVECTIVELY ENHANCED SHRTWV WILL MOVE EAST FROM NW IA THIS AFTN TO ERN WI/NE IL BY 06Z. CURRENTLY MESO-BETA ELEMENTS ASSOCIATED WITH THIS FEATURE WERE MOVG SSE HWVR SOME CONVECTION ALSO PUSHING EAST ACROSS NRN IA. CAN`T RULE OUT MORE WIDESPREAD CONVECTION DVLPG AHEAD OF THIS SHRTWV AND MOVG INTO OUR AREA BY LATE EVE BUT GIVEN CURRENT TRENDS WITH CONVECTION UPSTREAM HAVE LOWERED POPS TO CHC ACROSS NRN PORTIONS OF CWA IN THE 00Z-06Z TIMEFRAME. SHORT TERM... LATE TONIGHT INTO FRIDAY AND FRIDAY NIGHT... MAIN CONCERN IS THE SVR WEATHER POTENTIAL FRI INTO FRI NIGHT IN ACTIVE PATTERN AS POTENT UPPER TROUGH DIGS INTO THE NRN PLAINS AND UPPER MIDWEST FRI INTO FRI NIGHT. LATE TONIGHT/FRI MORNING...LEFT IN CHC POPS FOR SHOWERS/STORMS AS FA MAY BE IMPACTED BY CONVECTION/MCS CURRENTLY BACK IN IA WITH FURTHER DEVELOPMENT EXPECTED IN THE IA/SRN WI/NW IL VICINITY TONIGHT. 12Z MODELS CONTINUE TO STRUGGLE WITH MESOSCALE DETAILS WITH THE GFS HAVING CONVECTIVE FEEDBACK ISSUES AND THE 12Z NAM INITIALIZING POORLY WITH QPF. HOWEVER...AM CONFIDENT THAT AN ADDITIONAL MCS WILL DEVELOP OUT TO THE W WITH INCREASING LL CONV AHEAD OF POTENT UPPER TROUGH ALONG THETA-E/MOISTURE GRADIENT. WOULD THINK THAT THIS WOULD TRACK EASTWARD FOLLOWING PROGGED CORFIDI VECTORS/7H FLOW. ALSO WOULD EXPECT THE MCS TO TRACK NEAR/JUST SOUTH OF STRONG INSTABILITY/THETA-E BOUNDARY FROM LOWER MICHIGAN WNW TOWARD THE IL/WI BORDER. WITH THIS SAID...THINK THIS FEATURE WILL WEAKEN AS IT OUTRUNS BETTER FORCING WITH TRACK/SPEED IN QUESTION DUE TO LACK OF ANY GOOD MODEL GUIDANCE. AS A RESULT...WILL KEEP WITH CHC POPS DURING THIS TIMEFRAME DUE TO CONTINUED UNCERTAINTY. FRIDAY AFTERNOON...DEPENDING ON EVOLUTION OF MCS RENMANTS IT ONCE AGAIN LOOKS LIKE THE ATMOSPHERE WILL BECOME VERY UNSTABLE AS STEEPENING MID LEVEL LAPSE RATES COMBINED WITH VERY MOIST LOW LEVELS WILL YIELD MLCAPES AOA 2500 J/KG. NO OBVIOUS TRIGGER FOR SHOWER/STORM DEVELOPMENT WITH TIGHT THETA-E GRADIENT/DIFFUSE SFC TROUGH RETREATING OFF TO THE NORTH IN REPONSE TO HEIGHT FALLS ACROSS THE NORTH CENTRAL US. IF INSTABILITY IS REALIZED THINK IT WILL BE ENOUGH TO BREAK WEAK CAP NEAR 12KFT FOR SCT SHOWERS/STORMS...ESPECIALLY WITH OUTFLOW BOUNDARIES AROUND. DEEP LAYER SHEAR NEEDED FOR ROTATING UPDRAFTS/SUPERCELLS WILL LIKELY STAY OFF TO THE WEST...HOWEVER...HAIL/MICROBURST MULTICELLS A DISTINT POSSIBLITY WITH IMPRESSIVE CAPE...STEEP LL LAPSE RATES...AND SOMEWHAT DRY MID-LEVELS. FRIDAY NIGHT...MORE ORGANIZED SHOWER/STORM ACTIVITY SHOULD INITIATE FRI AFTN ALONG AND JUST AHEAD OF A PRE-FRONTAL TROUGH FROM NEAR MCI NE THRU DSM AND GRB. THIS ACTIVITY WILL LIKELY START OUT AS DISCRETE SUPERCELLS AND THEN ORGANIZE INTO A COLD POOL DRIVEN SQUALL LINE/LEWP...POSSIBLY AFFECTING THE REGION FROM WEST TO EAST FRI NIGHT. SVR WX A CONCERN WITH THIS AS IT MOVES THROUGH. DO NOT EXPECT THIS TO FALL APART AS WE LOSE DAYTIME HEATING DUE TO LARGE SCALE FORCING WITH DIFF PVA/HEIGHT FALLS...DIFFLUENT FLOW ALOFT IN RIGHT ENTRANCE REGION OF 100KT JET ROUNDING BASE OF TROUGH...AND LL CONV ALONG SFC TROUGH/OUTFLOW. CONTINUED WITH LIKELY POPS FOR FRIDAY NIGHT AND INCLUDED A SEVERE MENTION IN THE GRIDS. HEAVY RAIN DEFINITELY POSSIBLE FRIDAY INTO FRIDAY NIGHT WITH PWATS INCREASING TO NEAR 2 INCHES AND A DEEP WARM CLOUD LAYER NEAR 10KFT. LONG TERM... LITTLE CHANGE TO LONG TERM WITH OVERALL PACKAGE IN GOOD SHAPE. UNSETTLED WEATHER ON TAP FOR SATURDAY AFTERNOON WITH FRONTAL PASSAGE AND AGAIN ON SUNDAY WITH COLD AIR ALOFT AND MID LEVEL SHORTWAVE. MODELS ARE FAIRLY USELESS ON DETAILS FOR SATURDAY WITH THE NEAR TERM SO MUDDLED THAT INITIALIZATION ISSUES ABOUND. BUT THE LARGER DETAILS ARE STILL CONSISTENT SHOWING UPPER LOW SETTLING OVER GREAT LAKES AND ASSOC SFC FRONT ROLLING THROUGH ON SATURDAY AFTERNOON. MOISTURE/INSTABILITY SHOWN BY BUFR SOUNDINGS TO BE WELL ESTABLISHED AHEAD OF THE BNDRY. WHILE ACTIVITY COULD FIRE EARLY ALONG PRE FRONTAL TROF INDICATED BY NAM IT WILL LIKELY TURN OUT...AS HAS BEEN THE CASE IN RECENT DAYS...THAT DETAILS OF THE AFTERNOON EVOLUTION WILL BE LARGELY DEPENDENT ON FEATURES REMAINING FROM FRIDAY NIGHTS ACTIVITY TO THE WEST. COLD POOL THEN SETTLES IN WITH MODELS POORLY HANDLING STRENGTH AND LOCATION FROM RUN TO RUN WITH LARGE TIMING DIFFERENCES ON H5 SHORTWAVE ROTATING AROUND LOW. KEPT AFTERNOON POPS INTACT AND DID NOT ADD ANYTHING IN MORNING HOURS DUE TO LOW CONFIDENCE. DEEP LOW OVER EASTERN NA LIFTS WITH BROADER TROFING IN ITS WAKE KEEPING AREA UNDER UPPER NW FLOW THROUGH THE WEEK. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...STEINWEDEL LONG TERM...LUDINGTON AVIATION...SKIPPER UPDATE/NEAR TERM...TAYLOR in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 100 AM CDT FRI JUN 27 2008 .UPDATE... SEVERE WEATHER AND HEAVY RAIN POTENTIAL FROM NE MCS LOOKS LESS LIKELY AT THE MOMENT. SD CONVECTION MAY TURN OUT TO BE MORE SIGNIFICANT. NO CHANGES YET HOWEVER. ADDED 06Z TAF DISCUSSION. && .DISCUSSION... MAIN CONCERN TONIGHT IS OBVIOUSLY APPROACHING NE MCS. EXTRAPOLATION BRINGS THE LEADING EDGE TO MY SWRN ZONES AROUND 200 AM SO HAVE BOOSTED POPS SRN SECTIONS TO CATEGORICAL WORDING...NOW AREA WIDE. MEAN WIND AND CORFIDI VECTORS SUGGEST COMPLEX SHOULD NOT MOVE NORTH OF DUE EAST AND WILL LIKELY PUSH SOUTHEASTWARD WITH TIME. RUC 310K ISENT SFC FOCUSES MOISTURE CONVERGENCE INTO SWRN IA AS WELL ON NOSE OF 35-50KT LLJ WHICH WOULD ALSO KEEP COMPLEX MORE SOUTH THAN NORTH. WITH SRN IA NOW SEEMING TO BE UNDER THE GUN...WILL EXPAND FFA TO ALL AREAS ALONG AND SOUTH OF HIGHWAY 3...INCLUDING SWRN IA. NOT SURE ON HOW STRONG THE MCS WILL BE BY THE TIME IT GETS HERE. THERE IS SOME CONCERN THAT NRN KS MCS MAY STEAL SOME OF THE INFLOW POTENTIAL...AND RUC CINS COMPUTED FROM VARIOUS ELEVATED LEVELS SUGGEST VALUES ARE HIGH ENOUGH TO SUPPRESS STRENGTH SOMEWHAT. HOWEVER HIGHER MCS MAINTENANCE PROBS ADVANCE INTO IA OVERNIGHT WITH SHEAR AND MUCAPES...AND KINEMATIC FORCING FROM SHORT WAVE MAY BE ABLE TO OVERCOME ANY APPARENT INHIBITION. THUS SEE NO REASON WHY SVR AND HEAVY RAIN THREATS WILL NOT CONTINUE OVERNIGHT INTO IA. STRONG MOISTURE TRANSPORT...HIGH WCDS AND INCREASING PWS STILL SUPPORT HEAVY RAINS AND FLASH FLOOD WATCH. MEAN WIND IS ONLY 20-25 OVER IA BY 09Z AND CORFIDI VECTORS/MBE MOVEMENT EVEN LESS TO THE SOUTH. && .PREV DISCUSSION... (TONIGHT) ONCE AGAIN THE FORECAST FOR TONIGHT IS QUITE COMPLEX...MADE MORE DIFFICULT BY THE COUPLE ROUNDS OF CONVECTION AND THE RATHER STRONG COLD POOL ALOFT. TEMPERATURES THIS AFTERNOON...EVEN OUTSIDE OF THE CONVECTION...HAS HOVERED IN THE MID TO UPPER 60S WEST WITH LOWER TO MID 70S WEST. CAPE VALUES ARE STILL RESPECTABLE OVER SOUTHERN IOWA BUT NOT NEAR AS LARGE AS THEY WERE AND SHEAR REMAINS WEAK. GIVEN THAT CAPES ARE STILL AROUND 2000 J/KG AND LOW LEVEL MOISTURE IS STILL DECENT WITH A COLD POOL ALOFT...THERE WILL LIKELY BE SPOTTY SHOWERS AND ISOLATED THUNDERSTORMS THROUGH THE REST OF THE AFTERNOON AND EARLY EVENING. THE KICKER WILL BE A SHORTWAVE PUSHING ACROSS THE NORTHERN PLAINS WHICH SHOULD INITIATE THUNDERSTORMS OVER THE DAKOTAS AND NEBRASKA WHICH SHOULD THEN DEVELOP DOWN THE INSTABILITY AXIS OVER THE EASTERN DAKOTAS INTO WESTERN IOWA. THUNDERSTORMS WITH HEAVY RAINFALL WILL AGAIN BE LIKELY OVERNIGHT THROUGH FRIDAY MORNING. THE MODELS HAVE BEEN NO HELP AS THEY DO NOT REALLY PICK UP ON THE STRENGTH OF THE COLD POOL ALOFT AND THEY ARE ALL OVER THE PLACE WITH THE PRECIP AND QPF. FOR NOW THE BEST INTERPRETATION OF THE DATA SUGGESTS AN MCS OVER THE DAKOTAS...OR SEVERAL CLUSTERS OF STORMS TO THE WEST...WILL EVENTUALLY COME TOGETHER AND ROLL ACROSS CENTRAL IOWA LATE EVENING OR OVERNIGHT ONCE MORE AND PERSIST THROUGH THE BETTER PART OF FRIDAY. (FRI-THU) ACTIVE PERIOD WILL CONTINUE THROUGH FRIDAY BEFORE LARGE UPPER LEVEL SYSTEM CURRENTLY OVER ALBERTA DIVES SOUTHEAST INTO THE WESTERN GREAT LAKES ON SATURDAY...BUCKLING THE ZONAL FLOW TO A MORE NORTHWEST FLOW THROUGH THE REMAINDER OF THE FORECAST PERIOD. CERTAINLY UNCERTAINTIES PERSIST FOR FRIDAY AND WILL BE HIGHLY SUBJECTIVE TO WHAT OCCURS TONIGHT AND INTO FRIDAY MORNING. COLD FRONTAL BOUNDARY SHOULD REACH NORTHWEST IOWA BY 12Z AND PROGRESS SLOWLY THROUGH THE AREA AND BE OVER THE SOUTHEAST FORECAST AREA BY 21Z. REMNANTS OF AN MCS MOVING OUT OF SOUTH DAKOTA AND NORTHWEST IOWA TONIGHT SHOULD BE OVER PORTIONS OF THE AREA FRIDAY MORNING. MUCH LIKE TODAY...RECOVERY DURING THE DAY WILL BE DEPENDANT IF THE CLOUD COVER CAN BREAK BY LATE MORNING TO THE EARLY AFTERNOON. TEMPERATURES IN THE LOWER TO MID 80S BY THE AFTERNOON OVER THE SOUTHEAST WILL PUSH MIXED LAYER CAPES TO OVER 3000 J/KG. THE COLD FRONT MOVING INTO THIS INSTABILITY WOULD BE ENOUGH TO FIRE A MULTICELLULAR SQUALL LINE ALONG THE BOUNDARY THAT SHOULD THEN BE FAIRLY PROGRESSIVE MOVING EAST INTO THE EARLY EVENING HOURS. THE UPPER LEVEL CLOSED LOW PRESSURE SYSTEM WILL MOVE SOUTHEAST THROUGH MINNESOTA ON SATURDAY. WITH THE UPPER LEVEL ENERGY AND THE MID LEVEL COLD CORE PASSING NEARBY...SHOULD NOT HAVE MUCH PROBLEM INITIATING THUNDERSTORMS BY SATURDAY AFTERNOON OVER THE NORTHEAST HALF. GIVEN THE STEEP MID LEVEL LAPSE RATES...LOW MELTING LEVELS AND NEAR UNIDIRECTIONAL FLOW...LARGE HAIL MAINLY NICKEL SIZED OR LESS AND WIND GUSTS TO 60 MPH. WITH THE COOLER LOW TO MID LEVEL TEMPERATURES AROUND...HIGH TEMPERATURES WILL HAVE A DIFFICULT TIME RISING OUT OF THE 70S. COOL TEMPERATURES WILL PERSIST ON SUNDAY WITH A FEW SHOWERS AND THUNDERSTORMS POSSIBLE OVER THE NORTHEAST DURING THE AFTERNOON. GRADUAL WARMING NEXT WEEK. NEXT BEST CHANCE FOR THUNDERSTORMS WILL ARRIVE WEDNESDAY INTO THURSDAY. && .AVIATION...27/06Z SHOWERS AND THUNDERSTORMS WILL BEGIN AFFECTING TAF SITES BEGINNING AROUND 10Z AT FOD...AND OTHERS A FEW HOURS AFTER THAT. NORTHERN END OF NE CONVECTION APPEARS TO BE WEAKENING SOMEWHAT SO HAVE ONLY INCLUDED SHOWERS AND CB MENTION AT FOD. DID ADD THUNDER TO MCW/DSM TERMINALS HOWEVER AS SD STORMS APPEAR TO BE A BIT STRONGER...AND THUNDER FROM NEBRASKA SEEMS LIKE A BETTER BET FARTER SOUTH. CONFIDENCE IN TIMING AND DETAILS BY THE TIME IT REACHES ALO/OTM NOT GREAT ENOUGH TO INCLUDE ANYTHING BESIDES CB QUITE YET. THIS CONVECTION APPEARS WEAK ENOUGH THAT AIRMASS SHOULD RECOVER SUFFICIENTLY TO GENERATE ANOTHER ROUND OF STORMS WITH FRONTAL PASSAGE THIS AFTERNOON AND EARLY EVENING...HENCE THUNDER IN BODY OF TAF FOR ALL SITES. && .DMX WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH HIGHWAY 3 SOUTH TO MISSOURI BORDER TIL 12Z. && $$ FAB/RAD/BSS ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 120 AM EDT FRI JUN 27 2008 .AVIATION...QUIET NIGHT INTO THE MORNING HOURS STILL SEEMS FINE FOR THE TAF SITES...WITH THE EXCEPTION OF PATCHY FOG THAT MAY DEVELOP REDUCING VSBYS TO MVFR LEVELS OVERNIGHT. CONDITIONS BECOME MORE VOLATILE TOWARDS AFTERNOON AS A WARM FRONT LIFTS NORTH OVER THE GREAT LAKES. SHOWERS AND THUNDERSTORMS WILL IMPACT TVC FIRST BY MID-AFTERNOON AND POSSIBLY PLN/APN BY LATE AFTERNOON WITH MVFR/IFR VSBYS AND POSSIBLY CIGS. THE THREAT FOR SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO THE EVENING HOURS AS LOW PRESSURE TRACKS INTO THE WESTERN GREAT LAKES. MPC && PREV DISCUSSION... /ISSUED 1010 PM EDT THU JUN 26 2008/ UPDATE...LATEST RUC ANALYSIS AND IR/WV/RADAR IMAGERY SHOW A WEAK SURFACE LOW OVER THE THUMB OF MICHIGAN WITH SHALLOW COOL FRONT EXTENDING SW THROUGH SOUTHERN LAKE MICHIGAN AND NORTHERN ILLINOIS. WEAK SURFACE HIGH HAS NUDGED IN BEHIND THE FRONT ACROSS NORTHERN MICHIGAN...WHILE SHORTWAVE RIDGING AND CORRESPONDING SUBSIDENCE HAS DRIED THE REGION SUBSTANTIALLY ALOFT EXCEPT FOR CONVECTIVE DEBRIS CIRRUS. HOWEVER...COLUMN LOOKS TO MOISTEN IN EARNEST JUDGING BY 00Z UPSTREAM SOUNDINGS FROM GRB/MPX AHEAD OF A MCV OVER WESTERN WISCONSIN. DO NOT SEE MUCH OF A CHANCE OF PRECIP AS THIS MCV MOVES ACROSS CENTRAL AND SOUTHERN LOWER MICHIGAN OVERNIGHT...DUE TO A GENERAL LACK OF MOISTURE AND INSTABILITY...BUT IT WILL SERVE TO KEEP THE MORE CLOUDIER SKIES SOUTH OF M-72. A COUPLE OTHER NUISANT WX ITEMS TO DEAL WITH OVERNIGHT. FIRST...HIGHER DEWPOINT AIR MOVING OVER LAKE SUPERIOR HAS MAINTAINED MARINE FOG/STRATUS TOWARDS THE EASTERN PART OF THE LAKE...AND NW WINDS HAVE BEEN FUNNELING THE FOG/STRATUS ACROSS WHITEFISH BAY AND INTO THE SOO AT TIMES. WINDS SHOULD STAY PERSISTENT OUT OF THE NW FOR MOST OF THE NIGHT AND AM HARD PRESSED TO FIND A REASON FOR THE FOG/STRATUS TO DISSIPATE. SECOND...PORTIONS OF EASTERN UPPER/TIP OF THE MITT/NE LOWER DID NOT MIX OUT AS WELL AS LOCATIONS TO THEIR SW...AND MAY SEE PATCHY FOG DEVELOP LATE TONIGHT BARRING THE CLOUD COVER DOES NOT HINDER TEMPS TOO MUCH. OTHER THAN THESE MINOR CHANGES...JUST A FEW OTHER TWEAKS BUT JUST OF THE FORECAST IN GOOD SHAPE. MPC && PREV DISCUSSION... /ISSUED 344 PM EDT THU JUN 26 2008/ DISCUSSION...COOL FRONT HAS PUSHED SE OF OUR CWA LATE THIS AFTERNOON...WITH HIGH PRESSURE...SUBSIDENCE AND DRIER AIR FILTERING INTO NRN MICHIGAN. LINGERING CU FIELD ACROSS THE SE HALF OF OUR CWA IS GRADUALLY DIMINISHING IN RESPONSE TO BUILDING HIGH PRESSURE. ISOLD WEAK CONVECTION IS STILL TRYING TO FIRE AROUND NRN SAGINAW BAY ALONG OUR SE BORDER...BUT IS HAVING A HARD TIME STAYING TOGETHER AS IT SUCCUMBS TO INCREASING SUBSIDENCE AND STABILITY. ONE MORE QUIET NIGHT IS EXPECTED FOR NRN MICHIGAN BEFORE CONVECTION AGAIN GEARS UP ON FRIDAY AHEAD OF STRONG LOW PRESSURE...WITH WAVES OF CONVECTION EXPECTED TO IMPACT OUR AREA THRU MUCH OF THE WEEKEND AS THE LOW STALLS OVER THE WRN GREAT LAKES. TONIGHT...ANY REMAINING WEAK CONVECTION AROUND SAGINAW BAY SHOULD COME TO A CLOSE BEFORE 00Z. THEREAFTER...MAINLY CLEAR SKIES AND DRY WX CAN BE EXPECTED THRU TONIGHT. MID AND HIGH CLOUDS WILL BEGIN TO INCREASE ACROSS THE SW CWA OVERNIGHT IN ADVANCE OF A WARM FRONT LIFTING INTO THE WRN GREAT LAKES. LOW TEMPS OVERNIGHT WILL DROP INTO THE MID 50S TO LOWER 60S. FRIDAY...WARM FRONT WILL SLOWLY LIFT NE INTO OUR AREA...REACHING A LINE FROM THE ARROWHEAD OF MINNESOTA TO GREEN BAY TO SE LOWER MICHIGAN BY 00Z SATURDAY. AMPLE MOISTURE (1000-500 MB RH OF 90 PCT) WILL POOL ALONG AND NORTH OF THE FRONT...MAINLY DURING THE AFTERNOON. PLENTY OF LIFT TO GO AROUND...WITH AN ELONGATED AREA OF DPVA AND ISENTROPIC ASCENT (I305) DEVELOPING NORTH OF THE FRONT AS IT LIFTS INTO OUR CWA. ENHANCED 850 MB THETA E VALUES WILL ADVECT INTO THE REGION AS WELL. WIND FIELDS WILL INITIALLY BE WEAK FRIDAY MORNING...BUT WILL GRADUALLY STRENGTHEN DURING THE AFTERNOON. LL JET MAX WILL NOSE INTO LOWER MICHIGAN LATER IN THE DAY...AS 850 MB WINDS INCREASE TO 30-40 KTS. SEE NO REASON TO STRAY FROM CHANCE POPS CREEPING INTO LOCATIONS ALONG AND SOUTH OF M-72 DURING THE MORNING...SHRA/TSRA BECOMING LIKELY IN THE SW HALF OF OUR CWA IN THE AFTERNOON. NE HALF WILL SE CHANCE POPS IN THE AFTERNOON SLIGHTLY FARTHER AWAY FROM BETTER MOISTURE AND LIFT IMMEDIATELY NORTH OF THE WARM FRONT. REGARDING SVR WX POTENTIAL...BEST CHANCE WILL LIKELY BE LATER IN THE AFTERNOON AS WIND FIELDS STRENGTHEN...BEST DESTABILIZATION IS OCCURRING WITH PEAK HEATING AND FRONT IS NEARING SRN SECTIONS OF OUR CWA. HIGH TEMPS WILL BE MAINLY IN THE UPPER 70S AND LOWER 80S. LONG TERM...LOOKS TO BE A STORMY WEEKEND WITH A BREAK IN THE EARLY TO MID PART OF NEXT WEEK AND THEN A CHANCE FOR ANOTHER ROUND OF RAIN SHOWERS OR THUNDERSTORMS. TRIED TO MAKE SOME DISTINCTION BETWEEN RAIN AND NO RAIN OVER THE WEEKEND, BUT WITH THE GFS SUFFERING FROM CONVECTIVE FEEDBACK, ESPECIALLY SATURDAY OVER THE LOWER PENINSULA, TRIED TO BLEND LEANING TOWARD THE LESS CONTAMINATED MODEL, THE NAM FOR GUIDANCE. FRIDAY NIGHT/SATURDAY...INITIALLY, THE MODELS LOOK SIMILAR THROUGH ABOUT 06Z, WITH THE WARM FRONT MOVING UP THROUGH N LOWER. IT LOOKS LIKE THE RAIN SHOULD MOVE FROM SW TO NE THROUGH MOST OF N LOWER, THEN AFTER MIDNIGHT, THE RAIN MOVES INTO NE LOWER AND E UPPER. HOWEVER, THERE IS ENOUGH INSTABILITY AND DYNAMICS IN THE 500 MB JET (THE DIFLUENT AXIS OF THE JET RUNS THROUGH MICHIGAN). THERE WILL BE AT THE LEAST HIGH CHANCE POPS IN MOST OF THE STATE. THE CHANCES FOR SEVERE WEATHER WILL BE MOSTLY OVERNIGHT AS THE BEST BOUNDARY LAYER CAPE (AN APPROXIMATION FOR MIXED LAYER CAPE), LI, SI, AND 700-500 MB LAPSE RATES ARE OVERNIGHT INTO SATURDAY MORNING. THE ONLY THING TO WORRY ABOUT IS THE DEVELOPING DRY SLOT AS THE LOW STACKS UP IN WISCONSIN/W UPPER AROUND 18Z. WHICH WITH THE BULK SHEAR BEGIN GET INTO THE LOWER 40 KT RANGE AGAIN. SATURDAY NIGHT...WITH THE 500 MB LOW BEGINNING TO MEANDER OVER THE REGION, WOULD EXPECT THAT THE SFC BASED COMPONENT WITH THE CLOUDS AND THE LOSS OF SOLAR RADIATION. SO HAVE A CHANCE FOR RAIN AS THE SHOWERS UNDER THE LOW WILL TEND TO BE HIT AND MISS TO AN EXTENT. ALSO BY 12Z BOTH MODELS ARE BRINGING IN THE COLDER AIR AS THE 850 TEMPERATURES FALL BELOW 10C. SUNDAY...WITH THE MID LEVEL LAPSE RATES STEEPENING TO AROUND 7C/KM, WITH THE 500 MB LOW OVER US, WILL ALLOW FOR SHOWERS AND THUNDERSTORMS TO BECOME LIKELY. SUNDAY NIGHT...THE 500 MB LOW, WHICH IS FILLING, MOVES THROUGH SO WILL CONTINUE RAIN SHOWERS AND THUNDERSTORMS. EXTENDED (MONDAY THRU THURSDAY)...MONDAY, WITH THE LOW TO THE EAST OF THE REGION, THERE WILL BE RAIN SHOWERS, PROBABLY IN THE MORNING, AND THEN CLEAR OUT BY THE AFTERNOON, BUT IT BEING 4 DAYS OUT, WON`T GET CUTE. TUESDAY, THE 500 MB RIDGE AXIS IS EAST OF THE REGION AND SF HIGH PRESSURE IS BUILDING INTO THE REGION. SO DRY THROUGH THE DAY AND INTO THE EVENING. OVERNIGHT THE SHOWERS AND THUNDERSTORMS WILL PROBABLY MOVE INTO E UPPER AS THE COLD FRONT APPROACHES. WEDNESDAY, AS A LOW TRACKS INTO JAMES BAY, THE COLD FRONT DESCENDS AND BRINGS A CHANCE OF THUNDERSTORMS. THURSDAY, THE FRONT MOVES THROUGH THE REGION SO MORE FOR THE CHANCE OF THUNDERSTORMS. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTH PLATTE NE 201 AM CDT FRI JUN 27 2008 .SYNOPSIS... SEVERE WIND PRODUCING MCS CONTINUES TO EXIT EAST/SOUTHEAST OF THE FCST AREA EARLY FRIDAY MORNING. THIS MCS IS OCCURRING ALONG THE SOUTHERN FRINGE OF STRONGER MID/UPR LVL WESTERLY FLOW OVER THE NORTHERN PLAINS...AND AHEAD OF A SEASONABLY STRONG MID LVL S/W TROUGH LOCATED OVER SOUTHERN ALBERTA/SASKATCHEWAN...WITH TROUGH AXIS EXTENDING SOUTH INTO IDAHO/WYOMING. AS THE S/W TROUGH PROGRESSES EAST ACROSS THE GREAT PLAINS DURING FRIDAY...A SFC COLD FRONT WILL SURGE SOUTHEAST ACROSS THE REGION...BRINGING A MORE STABLE AND COOLER AIRMASS TO THE CENTRAL HIGH PLAINS. && .DISCUSSION... SHORT TERM MODEL GUIDANCE INDICATES A SFC BOUNDARY WILL MOVE SOUTHEAST THROUGH THE CWA BY 15-18Z FRIDAY...WHICH COULD SERVE TO FOCUS LATE MORNING/EARLY AFTERNOON THUNDERSTORM DEVELOPMENT. NAM SHOWS THAT MID LVL LAPSE RATES WILL REMAIN STEEP BENEATH A COOLING MID LVL AIRMASS...AND RESIDUAL BOUNDARY LAYER MOISTURE BEHIND DEPARTING MCS WILL BE PRESENT...YIELDING SUFFICIENT CAPE FOR DEEP MOIST CONVECTION. HIGHEST PROBABILITY OF THUNDERSTORM DEVELOPMENT APPEARS TO BE OVER OUR EASTERN COUNTIES...WHERE LOW LVL MOISTURE WILL BE GREATEST. THUNDERSTORMS ARE EXPECTED TO MOVE SOUTHEAST OF THE AREA BY LATE AFTERNOON...WITH TEMPERATURES BECOMING THE MAIN FCST PROBLEM FOR THE NEXT SEVERAL DAYS. AS UPR LVL VORTEX OVER SOUTH CENTRAL CANADA BEGINS TO SHIFT SOUTHEAST INTO THE NORTHERN PLAINS...A REINFORCING SHOT OF RELATIVELY COLD AIR IS EXPECTED TO MOVE SOUTH ACROSS THE CENTRAL PLAINS FRIDAY NIGHT. THIS WILL LEAD TO BELOW NORMAL OVERNIGHT LOWS FRIDAY NIGHT...AND BELOW NORMAL DAYTIME HIGHS ON SATURDAY. SAME TREND CONTINUES INTO SUNDAY...WITH COOLER MET GUIDANCE APPEARING MORE REASONABLE. IN ADDITION TO THE COOLER TEMPERATURES...SFC HIGH PRESSURE NOSING SOUTHEAST INTO THE PLAINS REGION DURING THE WEEKEND WILL SHUNT MOISTURE WELL SOUTH...FAVORING A DRY FORECAST THROUGH TUESDAY MORNING. NEXT CHANCE OF SHOWERS/THUNDERSTORMS APPEARS TO EMERGE AS UPR LVL TROUGH OVER THE EASTERN U.S. BEGINS TO SHIFT EAST...AND UPR RIDGE OVER THE WEST BEGINS TO BREAK DOWN A BIT...ALLOWING A WEAK LEE TROUGH TO DEVELOP. THIS CHANGING UPR LVL PATTERN MAY ALLOW STEEPER MID LVL LAPSE RATES TO CREEP EAST INTO THE CWA...ALONG WITH AN INCREASE IN LOW LVL MOISTURE...FAVORING A LOW PROBABILITY OF THUNDERSTORMS TUESDAY AFTERNOON AND NIGHT. && .AVIATION... CONVECTIVELY INDUCED FRONT INDICATED ACROSS NRN KS. A RETURN SERLY FLOW EXISTS ACROSS WRN AND CENTRAL NEBR. MAIN COLD FRONT STILL BACK ACROSS WRN NORTH DAKOTA INTO NERN WYOMING. USING LATEST OBJECTIVE RUC ANALYSIS...FRONT WILL MAKE A RAPID DESCENT INTO THE CENTRAL PLAINS AND SHOULD PASS THROUGH TAF SITE KVTN BY AROUND 13Z AND KLBF BY 15Z. WINDS TO BE MAINLY NORTH NORTHWEST AT 10 TO 20 KTS WITH HIGHER GUSTS BRIEFLY TO 25 KTS. A CHANCE FOR SHOWERS AND A FEW EMBEDDED THUNDERSTORMS FOR TAF SITE KVTN MAINLY BTWN 14Z AND 20Z WITH PASSAGE OF MID LEVEL TROUGH. ALTHOUGH NO TEMPO INSERTED FOR TSRA...WILL MONITOR MODEL TRENDS AND SATELLITE AND RADAR FOR POSSIBLE ADDITION TO 12Z TAF. SKIES SHOULD BECOME SKC AFT 00Z SATURDAY FOR BOTH TAF SITES. && .LBF WATCHES/WARNINGS/ADVISORIES...NONE. && $$ GARNER/ROBERG ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 430 AM CDT FRI JUN 27 2008 .DISCUSSION...TODAY THROUGH SUNDAY NIGHT. UPPER LEVEL SYSTEM WILL DIG INTO THE NORTHERN PLAINS TODAY. WATER VAPOR LOOP SHOWS CIRCULATION CENTER OVER NORTHERN AB/SK BORDER WITH SHORT WAVE OVER THE SOUTHERN AB/SK BORDER. SHORT WAVE WAS DIGGING SOUTHEAST ABOUT 35 KNOTS. COLD FRONT OVER NORTHWEST ND WILL MOVE THROUGH THE AREA THIS AFTERNOON. MESOSCALE ANALYSIS SHOWS BEST PRESSURE FALLS WERE OVER SOUTHEAST ND. E-W LOW LEVEL THETA-E GRAD WAS OVER EASTERN ND. RUC MAINTAINS PRESSURE FALLS OVER FORECAST AREA THIS MORNING. PRESSURE RISE CENTER OVER MT/SK/AB BORDER MOVES INTO THE WESTERN DAKOTAS LATER THIS MORNING WITH COLD FRONT MOVING IN. AREA VAD WINDS INDICATE FLOW ABOVE 850 HPA WAS OUT OF THE WEST WHILE BELOW 850 HPA THE FLOW WAS SOUTH OR SOUTHEAST. NO MODEL HANDLED THE FLOW VERY WELL BELOW 850 HPA. BEST INSTABILITY WAS OVER NORTHWEST MN AND INTO SOUTHEAST ND. THUNDERSTORMS HAVE DEVELOPED ALONG THETA-E GRADIENT THIS MORNING. EXTENDED...MONDAY AND TUESDAY. NO CHANGES MADE TO ZONES. && .AVIATION... APPARENTLY SOME FOG OVER DVL THIS MORNING. OTHERWISE REST OF AREA VFR WITH CIGS MOSTLY ABOVE 10 THOUSAND FT. CIGS LIKELY LOWER IN -TSRA. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ HOPPES nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 615 AM EDT FRI JUN 27 2008 .SYNOPSIS... PIECES OF ENERGY ALOFT KEEP THE MENTION OF SHOWERS AND THUNDERSTORMS IN THE FORECAST THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK. A COLD FRONT MOVES THROUGH LATE SATURDAY NIGHT. && .NEAR TERM /THROUGH TONIGHT/... CHALLENGING NEAR TERM FCST AS IT IS DRIVEN IN LARGE PART BY MESOSCALE FEATURES. WEAK S/W IS WORKING THRU WRN OH AND CNTRL KY ATT WHICH IS GENERATING SCT RW/TRW. RUC13 AND LCL WRF RESOLVE TRW FILLING IN ACR THE ERN KY COALFIELDS DURING THE PREDAWN THEN MOVING OVER FAR SRN WV AND SWRN VA THIS MRNG. ACTIVITY IN OHIO SHOULD WEAKEN AND/OR LIFT NE. DO NOT SEE MUCH TO FOCUS STORM INITIATION UNTIL DAYTIME HEATING COMMENCES OUTSIDE THE AFOREMENTIONED S/W IN THE COAL FIELDS. NONETHELESS...WITH POCKETS OF DCVA CROSSING CARRY AT LEAST AN ISOLD MENTION THIS MRNG. CHC POPS WORK THIS AFTN WITH NOTHING MORE THAN SOLAR HEATING TRIGGERING STORMS. KINEMATICS ARE WEAK /0-6KM BULK SHEAR < 20KTS/. EQ LVL EXCEEDS 40KFT...FZL LVL 15KFT...AND PWATS PUSH 2.0 OWING TO WATER LOADING...THEREFORE EXPECT TALL STORMS AND DOWNPOURS. SREF PROB OF 2.0 KJKG-1 OF MLCAPE IS LESS THAN 30% AND THE LACK OF UPR LVL FORCING AND LOW SHEAR PROBS DO NOT FORESEE ORGANIZED STORMS. TNGT CARRIES MORE QUESTION MARKS THAN TDY. GFS/NAM BOTH HINT AT AN MCS DEVELOPING IN THE CNTRL PLAINS AND TREKKING E OVER THE OH VLY. GFS IS FARTHEST E BRINGING AN AREA OF STG H2 AGEO WIND DIV OVER THE CWA BTWN 6-12Z. MEANWHILE...NAM IS NOT AS FAST BRINGING THE MCS THROUGH BTWN 12-18Z SAT. OPTED FOR THE MIDDLE ROAD /TIMING WISE/ WITH A DROP TO SCHC POPS MOST OF THE NGT THEN AN INC TO CHC OVER NWRN ZNS B4 DAYBREAK SAT. H8 DWPTS OF 12C...NOCTURNAL LLVL JET...AND HIGH SREF PROBS OF CINH LESS THAN 50JKG-1 WARRANTS A MENTION OF PCPN ALL NGT. && .SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/... STRONG COLD FRONT APPROACHES SAT AND MOVES THROUGH SUN. BEST JUICE IS SAT IN THE W WITH DEW POINTS AROUND 70...H8 THETA E VALUES TO 340K AND UP TO 2500 J/KG OF CAPE. FLOW STRENGTHENS WITH HEIGHT FALLS AND TIGHTENING GRADIENT AHEAD OF THE FRONT. PRECIP LOADING AND HIGH FREEZING LEVEL WILL BE THE ONLY LIMITING FACTORS FOR SEVERE WEATHER AS PW VALUES ARE FORECAST TO GET AS HIGH AS 2 INCHES. WITH THE POTENTIAL FOR HEAVY RAINFALL...WE WILL OF COURSE NEED TO KEEP TRACK OF WHERE THE HEAVY RAINFALL OCCURS REPEATEDLY. FORCING IS PROVIDED BY UPPER LEVEL DIVERGENCE...DIFFERENTIAL VORTICITY ADVECTION AND CONVERGENT LOW LEVEL INFLOW. THERE IS SOME MODEL CONVERGENCE ON MCS ROLLING THROUGH SAT MORNING SO HAVE POPS ALREADY INCREASING FROM THE W THEN. AS THE FRONT GETS CLOSER SAT NT...THUNDERSTORMS MAY BECOME A BIT WEAKER AND LESS NUMEROUS WITH THE LESS OF HEATING BUT SHOULD NOT GO AWAY ALTOGETHER. FRONT BECOMES HARDER TO FIND SUN AS LOW LEVEL CONVERGENCE ACTUALLY WEAKENS. NONETHELESS...SUN WILL BE RATHER BREEZY WITH GOOD MIXING AND DEEP LAYER SW FLOW. WITH LOWER PW AND FREEZING LEVEL...THE THREAT FOR HEAVY RAIN DECREASES WHILE THE CHANCE FOR HAIL COMES UP. THE UPPER LEVEL LONG WAVE TROUGH...RATHER AMPLIFIED AS WE TRANSITION FROM JUN TO JUL...MOVES ONLY SLOWLY ACROSS THE AREA THROUGH MON NT. BY THIS TIME...WE HAVE MAINLY THE DIURNALLY DRIVEN CONVECTION AS THE SUN HEATS THE GROUND UNDERNEATH THE COLD AIR ALOFT. HAIL WILL LIKELY BECOME A BIGGER THREAT THAN WIND MON. INDIVIDUAL SHORT WAVE TROUGHS MOVING THROUGH THE LONG WAVE ARE OF COURSE HARD TO TIME AT THIS TIME...BUT WILL LIKELY MODULATE DIURNAL CYCLE IN SOME WAY. INHERITED HIGH FORECAST FOR SAT WAS BETWEEN THE HIGH MAV/FWC AND THE LOW MET...CLOSER TO THE HIGHER NUMBERS. LEFT THIS ALONG AS HIGHS WILL BE A FUNCTION OF THE CLOUDS AND RAIN...THE MET REFLECTING A CLOUDIER...WETTER AND THUS COOLER SOLN...WITH ITS POPS INDEED HIGHEST. RAISED LOWS SAT NIGHT IN THE MIXED WARM SECTOR AIR AHEAD OF THE COLD FRONT. SUN HIGHS WERE JUST ABOVE THE HIGHEST NUMBERS...OPTED TO LEAVE AS IS FOR NOW. NO MAJOR CHANGES SUN NT THRU MON NT AS WE ARE JUST ABOVE THE MEX IN MOST CASES. && .LONG TERM /TUESDAY THROUGH THURSDAY/... PERIOD BEGINS WITH SHARPENING OF H5 TROUGH OVER EASTERN CONUS FOR DAYS 4-5. DIFFICULT TO PIN DOWN TIMING ON VORT LOBES ROTATING THROUGH BASE OF MID LEVEL TROUGH THIS FAR OUT. GENERALLY FOLLOWED HPC SOLUTION...WHICH FAVORS ECMWF EARLY IN THE EXTENDED AND ECMWF ENSEMBLES REMAINDER OF EXTENDED. THIS PUTS CWA IN LOW CHC POPS ON MONDAY...SHIFTING TO THE EAST AND DIMINISHING BY TUESDAY. H5 TROUGH QUICKLY LIFTS OUT ON WEDNESDAY...REPLACED BY MORE OF A ZONAL FLOW. AT THE SFC...HIGH PRESSURE WILL BUILD IN FOR WEDNESDAY THROUGH FRIDAY. WENT MORE OPTIMISTIC THAN HPC ON SKIES DAYS 4-5...DUE TO UNCERTAINTY IN TIMING OF MID LEVEL FEATURES. TEMPS FROM HPC LOOK GOOD AND GENERALLY FOLLOWED SUIT. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... ANY MVFR VIS RESTRICTIONS LIFTS BY 14Z. SCT RW/TRW ARE XPCTD THE BALANCE OF THE FCST. TOO TOUGH TO PINPOINT TIMING AND LOCATION AT A TERMINAL...SO ROLLING WITH CB. MVFR VIS WL DEVELOP AT EKN AFT 6Z AND ANY SITE THAT EXPERIENCES RA DURING THE DAY. .AVIATION OUTLOOK /AFTER 12Z SAT/...IFR PSBL IN TRW THRU MON...MAINLY AFTN/EVNG. && .HYDROLOGY... ATMS REMAINS RIPE FOR DOWNPOURS THROUGH SAT AS PWATS PUSH 2.0 INCHES...WEAK STEERING FLOW...AND STG BL EQUIV POT TEMP ADV ARE FCST. NOT TO MENTION...ONE OR MORE MCS MAY CROSS THE AREA. OUR MOST VULNERABLE AREAS ARE PERRY AND MORGAN COUNTIES...BUT DUE TO THE UNCERTAINTY OF TIMING/PLACEMENT/QPF ELECTED NOT TO HOIST A FLASH FLOOD WATCH THIS MRNG. DO NOT BE SURPRISED IF ONE IS ISSUED LATER TODAY ONCE WE CAN BETTER DISCERN STORM PLACEMENT. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/29 NEAR TERM...29 SHORT TERM...TRM LONG TERM...30 AVIATION...29 HYDROLOGY...29 oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 435 AM EDT FRI JUN 27 2008 .SYNOPSIS... WEAK WEATHER DISTURBANCES ALOFT WILL INTERACT WITH A MOIST AND UNSTABLE AIRMASS TO PRODUCE SHOWERS AND THUNDERSTORMS ACROSS THE REGION THROUGH SATURDAY. A STRONG UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE TO THE GREAT LAKES AND OHIO VALLEY REGION SATURDAY NIGHT....PUSHING A COLD FRONT SOUTHEAST THROUGH THE REGION. THE UPPER LEVEL LOW WILL LINGER ACROSS THE REGION THROUGH THE FIRST PART OF THE WEEK...RESULTING IN COOLER TEMPERATURES AND A CONTINUED THREAT FOR SHOWERS AND THUNDERSTORMS. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... HAVE MAINLY USED THE RUC MODEL FOR THE NEAR TERM FORECAST. A MCV WAS LOCATED OVER CENTRAL OHIO EARLY THIS MORNING. THIS FEATURE HAS RESULTED IN A FLARE UP OF SHOWERS AND ISOLATED THUNDERSTORMS ACROSS CENTRAL OHIO. THIS SYSTEM IS EXPECTED TO BE EAST OF THE FORECAST AREA BETWEEN 10Z AND 12Z...BY WHICH THE THREAT FOR WIDESPREAD PCPN IS EXPECTED TO COME TO AN END. CURRENT ZONES/GRIDS REFLECT THE HIGH THREAT FOR PCPN EARLY THIS MORNING. OTHERWISE...A MOIST AND UNSTABLE AIRMASS WILL REMAIN ACROSS THE REGION TODAY. THE RUC MODEL INDICATES THAT A SHEARED OUT VORTICITY AXIS WILL TRAVERSE THE FORECAST AREA BETWEEN 16Z AND 21Z. THIS FEATURE...ALONG WITH ANY SUBTLE MESOSCALE SURFACE BOUNDARY/WEAK AREA OF LOW LEVEL CONVERGENCE...WILL RESULT IN ABOUT A 40 PERCENT CHANCE OF SHOWERS AND THUNDERSTORMS...MAINLY DURING THE AFTERNOON HOURS. AN ISOLATED SEVERE STORM CAN NOT BE RULED OUT...BUT IF IT WERE TO OCCUR...IT SHOULD BE OF THE PULSE TO MULTICELL VARIETY GIVEN OVERALL WEAK SHEAR. HIGHS TODAY WILL RANGE FROM THE UPPER 80S NORTH TO NEAR 90 ALONG AND SOUTH OF THE OHIO RIVER. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... THE SHORT TERM FORECAST BECOMES COMPLEX TONIGHT THROUGH SATURDAY. THE OPERATIONAL NAM-WRF AND GFS GENERALLY AGREE ON THE TIMING OF SYNOPTIC SCALE SYSTEMS. IT IS THE MESOSCALE...ALONG WITH THE TIMING OF SHOWERS AND THUNDERSTORMS...THAT IS SOMEWHAT MURKY AT THIS POINT IN TIME. AN UPPER LEVEL LOW PRESSURE SYSTEM WILL DIG SOUTHEAST OUT OF WRN CANADA...MOVING TO THE WRN GREAT LAKES BY SATURDAY EVENING. AN ASSOCIATED COLD FRONT WILL ACCOMPANY THE UPPER LEVEL LOW. HOWEVER...THIS FRONT IS FORECAST TO MOVE THROUGH OUR AREA SATURDAY NIGHT. BEFORE THEN...BOTH MODELS HINT AT THE POSSIBILITY OF AN MCS DEVELOPING ACROSS THE MID MS RIVER VALLEY LATE THIS AFTN/EVENING...THEN MOVING IT QUICKLY EAST ACRS THE FORECAST AREA SOMETIME AFTER 06Z. IF THIS MCS FORMS...IT SHOULD BE SUSTAINED BY A DEVELOPING 925 MB-850 MB JET. AGAIN...IT IS THE TIMING THAT IS UNCLEAR AT THIS POINT. HAVE DECIDED TO RAMP UP POPS ACRS THE FCST AREA AFTER MIDNIGHT TONIGHT...AND THIS IS IN COLLABORATION WITH MOST OF THE SURROUNDING OFFICES. SPC SWODY1 HAS JUST OUR WRN FORECAST AREA UNDER A SLIGHT RISK OF SEVERE STORMS TONIGHT...MOST LIKELY BANKING THAT THE INTENSITY OF THE THUNDERSTORMS WILL WEAKEN AS IT HEADS EAST INTO A REGION WITH LESS FAVORABLE CAPES. AGAIN...THIS IS PROBLEMATIC AT THIS POINT...AND WHAT TRANSPIRES THIS AFTN AND EVENING WILL HAVE TO BE WATCHED CLOSELY. ON SATURDAY...CONVECTION FROM POTENTIAL MCS WILL LIKELY BE ONGOING EARLY. THEN...MODELS HINT AT A PREFORNTAL TROF DEVELOPING ACRS THE REGION OUT AHEAD OF THE COLD FRONT. AGAIN...WITH A MOIST AND UNSTABLE AIRMASS...SHOWERS AND THUNDERSTORMS WILL BE LIKELY. IT SHOULD BE NOTED AT THIS POINT THAT FFG VALUES CONTINUE TO REMAIN LOW ACRS PARTS OF W CNTRL AND CNTRL OHIO FROM RECENT RAINS. NEXT FORECAST SHIFT...IF IT APPEARS THAT AN MCS WILL INDEED CROSS THE REGION TONIGHT FOLLOWED BY MORE SHOWERS AND THUNDERSTORMS ON SATURDAY...WILL HAVE TO DECIDE ON A POSSIBLE FLASH FLOOD WATCH GIVEN PRECIPITABLE WATER VALUES OF 1.50 TO 2.00 INCHES EXPECTED TONIGHT AND SATURDAY. AFOREMENTIONED UPPER LEVEL LOW PRESSURE SYSTEM IS FORECAST TO SETTLE ACRS THE GREAT LAKES AND OHIO VALLEY REGION LATE SATURDAY NIGHT INTO SUNDAY...SENDING A COLD FRONT SOUTHEAST THROUGH THE REGION. IT APPEARS THAT A DRY SLOT WILL FORM BEHIND THE FRONT...BRINGING DRY WEATHER FOR A TIME LATE SATURDAY NIGHT INTO SUNDAY MORNING ACRS OUR REGION. THEREAFTER...WRAP AROUND MOISTURE WITH THE UPPER LEVEL LOW...ALONG WITH COLDER TEMPERATURES ALOFT...WILL RESULT IN A CHANCE OF SHOWERS AND THUNDERSTORMS. THE THREAT FOR SHOWERS AND STORMS WILL LINGER ACROSS THE REGION SUNDAY NIGHT INTO MONDAY NIGHT AS THE UPPER LEVEL LOW SLOWLY TRAVERSES THE REGION. TEMPERATURES WILL UNDERGO A COOL DOWN AFTER SATURDAY/S HIGHS IN THE LOWER AND MID 80S. CURRENT FORECAST HIGHS IN THE MID AND UPPER 70S SUNDAY AND MONDAY MAY HAVE TO BE TWEAKED DOWN...ESPECIALLY ON MONDAY...IF MODELS CONTINUE TO SUPPORT 850 MB TEMPS BELOW 10 C. && .LONG TERM /TUESDAY THROUGH THURSDAY/... HIGH PRESSURE BUILDS AND MOVES EAST OF THE REGION TUESDAY THROUGH THURSDAY. DRY WX ALONG WITH A STEADY WARMING TREND IS EXPECTED. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... WELL DEFINED MCV MOVING ACRS FCST AREA ATTM. HAVE SEEN SOME REDVLPMNT TO SCT SHRA BTWN THE DAY AND CMH METROS SOUTH TO AROUND KILN OVER THE LAST TWO HOURS. MCV PROGGED TO TAKE A GOOD PART OF THE NIGHT TO MOVE EAST ACRS FCST AREA AND WITH 03Z RUC INDCG LO LVL CONV AND WEAK ELEVATED INSTABILITY...EXPECT SCT SHRA WILL PERSIST FOR THE NEXT SVRL HOURS INVOF THE MCV. CANNOT RULE OUT A RUMBLE OF THUNDER BUT INSTABILITY IS WEAK ENUF TO LEAVE OUT OF TERMINALS ATTM. HAVE PLACED VCSH IN AT KDAY AND KILN THRU 09Z...AND AT KCMH/KLCK THRU 12Z. ONCE MCV SHIFTS EAST AROUND DAYBREAK...EXPECT A GENERALLY QUIET MRNG WITH ONLY MID/HI LVL CLOUD BLOWOFF FROM CONVECTION TO THE WEST. MODEL SOUNDINGS INDCG THAT ONCE AGAIN THE ATMOSPHERE WILL BECOME MODERATELY UNSTABLE BY ERLY AFTN. MID LVL FORCING IS GENERALLY WEAK AND DISORGANIZED THIS AFTN. CONVECTION WILL FIRE ALONG LEFTOVER MESOSCALE BNDRYS FROM TSRA THIS EVNG AND CURRENT ACTIVITY AND WILL BE MOST NUMEROUS DURING THE MID/LATE AFTN DURING PEAK HEATING. WILL PLACE CB IN ALL TERMINALS THIS AFTN BUT ANY ADDL DETAIL IS DIFFICULT ATTM. SHOULD SEE A GENERAL LULL IN ACTIVITY THIS EVNG AS DIURNAL HEATING IS LOST. 00Z MODELS INDCG SIGNIFICANT CONVECTION POSSIBLY IN THE FORM OF A DERECHO/SQUALL LINE AFFECTING TERMINALS AFT 06Z SAT. WILL ADDRESS THIS IN GREATER DETAIL WITH NEXT SET OF TERMINALS. OUTLOOK...THUNDERSTORMS POSSIBLE THROUGH MONDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HICKMAN NEAR TERM...HICKMAN SHORT TERM...HICKMAN LONG TERM... AVIATION...RYAN oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 139 AM EDT FRI JUN 27 2008 .SYNOPSIS... A MOIST AND UNSTABLE AIRMASS WILL REMAIN ACROSS THE REGION THROUGH THE END OF THE WEEK. AS WEAK DISTURBANCES MOVE ACROSS THE AREA...SHOWERS AND THUNDERSTORMS WILL OCCUR. A STRONG UPPER LEVEL SYSTEM AND ASSOCIATED COLD FRONT WILL AFFECT THE GREAT LAKES AND OHIO VALLEY OVER THE WEEKEND. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... BAND OF SHOWERS AND STORMS AHEAD OF AN APPROACHING MCV IS STEADILY WEAKENING AS THE BOUNDARY LAYER STABILIZES. WENT AHEAD AND KEPT THE FLASH FLOOD WATCH GOING ACROSS CENTRAL OHIO UNTIL PRECIP TOTALLY CLEARS THIS AREA...BUT DROPPED THE FFA FURTHER WEST. CANNOT RULE OUT ISOLATED SHRA/TSRA OVERNIGHT AS CENTER OF MCV ROTATES THROUGH...MOSTLY ALONG AND NORTH OF I-70. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/... OPERATIONAL MODELS NOT INDICATING MUCH ACTIVITY FRIDAY INTO FRIDAY NIGHT. BUT THEY GENERALLY HAVE A DIFFICULT TIME FORECASTING MESOSCALE TRIGGERS. ENVIRONMENT WILL REMAIN UNSTABLE AND CAN FOR SEE SCATTERED CONVECTION DEVELOPING ONCE AGAIN IN THE AFTERNOON AND CONTINUING INTO THE EVENING. ALSO COULD START TO SEE SOME ACTIVITY LATE FRIDAY NIGHT WELL AHEAD OF AN ADVANCING COLD FRONT. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... SATURDAY...THE MODELS ARE IN GENERAL AGREEMENT WITH THE POSITION OF THE COLD FRONT...ALTHOUGH THE GFS IS FASTER WITH PCPN ONSET THAN THE ECMWF. STORMS WILL BE LIKELY DURING THE AFTERNOON. THE SCT/NUMEROUS PCPN COVERAGE WILL LIKELY LINGER INTO EARLY SUNDAY. AGAIN...HIGH TEMPERATURES WILL BE HIGHLY INFLUENCED BY THE RAIN SATURDAY...WITH HIGHS MAINLY IN THE MID 80S. SEASONABLY COOL AIR SETTLING IN BEHIND THE FRONT ON SUNDAY. A TRAILING UPPER TROF WILL LINGER SCT SHOWERS/STORMS INTO MONDAY...WITH SEASONABLY COOL TEMPERATURES PERSISTING. THEN...HIGH PRESSURE BUILDS AND MOVES EAST OF THE REGION THROUGH THURSDAY...WITH A STEADY WARMING TREND. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... WELL DEFINED MCV MOVING ACRS FCST AREA ATTM. HAVE SEEN SOME REDVLPMNT TO SCT SHRA BTWN THE DAY AND CMH METROS SOUTH TO AROUND KILN OVER THE LAST TWO HOURS. MCV PROGGED TO TAKE A GOOD PART OF THE NIGHT TO MOVE EAST ACRS FCST AREA AND WITH 03Z RUC INDCG LO LVL CONV AND WEAK ELEVATED INSTABILITY...EXPECT SCT SHRA WILL PERSIST FOR THE NEXT SVRL HOURS INVOF THE MCV. CANNOT RULE OUT A RUMBLE OF THUNDER BUT INSTABILITY IS WEAK ENUF TO LEAVE OUT OF TERMINALS ATTM. HAVE PLACED VCSH IN AT KDAY AND KILN THRU 09Z...AND AT KCMH/KLCK THRU 12Z. ONCE MCV SHIFTS EAST AROUND DAYBREAK...EXPECT A GENERALLY QUIET MRNG WITH ONLY MID/HI LVL CLOUD BLOWOFF FROM CONVECTION TO THE WEST. MODEL SOUNDINGS INDCG THAT ONCE AGAIN THE ATMOSPHERE WILL BECOME MODERATELY UNSTABLE BY ERLY AFTN. MID LVL FORCING IS GENERALLY WEAK AND DISORGANIZED THIS AFTN. CONVECTION WILL FIRE ALONG LEFTOVER MESOSCALE BNDRYS FROM TSRA THIS EVNG AND CURRENT ACTIVITY AND WILL BE MOST NUMEROUS DURING THE MID/LATE AFTN DURING PEAK HEATING. WILL PLACE CB IN ALL TERMINALS THIS AFTN BUT ANY ADDL DETAIL IS DIFFICULT ATTM. SHOULD SEE A GENERAL LULL IN ACTIVITY THIS EVNG AS DIURNAL HEATING IS LOST. 00Z MODELS INDCG SIGNIFICANT CONVECTION POSSIBLY IN THE FORM OF A DERECHO/SQUALL LINE AFFECTING TERMINALS AFT 06Z SAT. WILL ADDRESS THIS IN GREATER DETAIL WITH NEXT SET OF TERMINALS. OUTLOOK...THUNDERSTORMS POSSIBLE THROUGH MONDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS... NEAR TERM...HAWBLITZEL SHORT TERM... LONG TERM... AVIATION...RYAN oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PHOENIX AZ 915 AM MST FRI JUN 27 2008 SOUTH-CENTRAL AND SOUTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA FORECAST DISCUSSION .SYNOPSIS... HIGH PRESSURE ALOFT WILL REMAIN THE DOMINANT WEATHER FEATURE THROUGH THE MIDDLE OF NEXT WEEK. THE HIGH WILL MOVE NORTHWARD TOWARD THE FOUR CORNERS THIS WEEKEND...RESULTING IN WARMER TEMPERATURES. HIGH TEMPERATURES ON THE DESERTS COULD EXCEED 110 DEGREES SUNDAY AND MONDAY...BEFORE A GRADUAL COOLING TREND DEVELOPS NEXT WEEK. ISOLATED THUNDERSTORMS WILL REMAIN A THREAT AS WELL...BUT ONLY ACROSS THE HIGHER TERRAIN WELL EAST OF PHOENIX. && .DISCUSSION... EARLY MORNING SOUNDINGS AT PSR AND TUS INDICATED A SLIGHT DECREASE IN THE PRECIP WATER AS A WEAK UPPER LEVEL TROUGH MOVED NORTHEAST AND INTO NEW MEXICO. FGZ WAS A BIT HIGHER COMPARED TO EARLY THURSDAY MORNING...WITH THE BULK OF THE MOISTURE IN THE LAYER BETWEEN 10 THSD AND 18 THSD FT. IR/WATER VAPOR IMAGERY ALSO SHOWED THE SIGNIFICANT DECREASE IN MID AND HIGH LEVEL CLOUDINESS IN SOUTHERN AND SOUTHEAST ARIZONA BETWEEN MIDNIGHT AND 8 AM MST. NAM APPEARED TO HAVE THE BEST HANDLE ON THE VORTICITY PATTERN AND SHOWED THE 300MB WINDS SHIFTING SLIGHTLY AS THE EASTERN PACIFIC TROUGH REMAINS OUT NEAR 32N/125W. AGREE WITH PREVIOUS DISCUSSION IN THAT THE NAM HAS A SLIGHT EDGE OVER THE DRIER GFS WITH REGARD TO THE LOW LEVEL MOISTURE PATTERN. REL HUMIDITY AS DEPICTED ON LATEST RUC WAS WAY OVERDONE. SO...A RATHER TRANQUIL DAY IS UNDERWAY ON THE DESERTS. BUT THE SLIGHT CHANCE OF AFTERNOON/EVENING THUNDERSTORMS STAYS WITH US FOR ZONE 24 DUE TO DESTABILIZED LAPSE RATES AND SOME CAPE. FROM PREVIOUS DISCUSSION... ON SATURDAY THE LOW OFF THE CA COAST STARTS TO BUILD THE RIDGE...AND THE 500MB HIGH CENTER STARTS TO SHIFT NORTH. STILL...AS THIS OCCURS LOW/MID LEVEL WINDS MAINTAIN A SWLY/WESTERLY DIRECTION AND LOW LEVEL MOISTURE STAYS LOW. STEERING FLOW REMAINS UNFAVORABLE TO BRING STORMS INTO THE LOWER DESERTS...SO WE WILL CONTINUE A SLIGHT CHANCE FOR AFTN/EVE STORMS ONLY OVER ZONE 24. AS H5 HEIGHTS CLIMB ABOUT 20M...MAX TEMPS SHOULD RISE A COUPLE OF DEGREES...AND REACH TO 110 AT PHOENIX. SUNDAY APPEARS TO BE THE DAY WITH THE BEST CHANCE FOR AFTERNOON AND EVENING CONVECTION OVER SOUTH-CENTRAL ARIZONA...AS BOTH THE GFS AND EUROPEAN CONTINUE TO BUILD THE RIDGE AND MOVE THE HIGH CENTER TO THE FOUR CORNERS AREA...OR EVEN FURTHER NORTH. AT THE SAME TIME MEAN 700-300MB STEERING FLOW BECOMES SOUTHEASTERLY OVER OUR ERN CWA. DESPITE THE MORE FAVORABLE ORIENTATION OF THE RIDGE AND THE STEERING FLOW...850MB DEWPOINTS DO NOT REALLY SURGE WESTWARD MUCH AND REMAIN LOW FROM PHOENIX WEST. DYNAMICS SUNDAY EVENING ARE FAVORABLE...WITH GOOD DIFFLUENCE ALOFT SEEN IN THE GFS UPPER STREAMLINE FIELDS. AS SUCH...POPS WILL BE RAISED SUNDAY EVENING TO ABOUT 20 PERCENT OVER ZONE 24...WITH 5 PERCENT POPS INTO THE PHOENIX AREA. AS CONFIDENCE INCREASES IN THE CHANCES FOR CONVECTION SUNDAY...POPS CAN CERTAINLY BE RAISED IN FUTURE PACKAGES. ONE POSSIBLE MITIGATING FACTOR...HEIGHTS BUILD FURTHER ON SUNDAY...TO ABOUT 593/594DM OVER SOUTH-CENTRAL AZ. STRONG WARMING ALOFT COULD TEND TO CAP...AND LIMIT...CONVECTION. SUNDAY SHOULD BE THE WARMEST OF THE NEXT 7 DAYS...AND IT IS NOT OUT OF THE QUESTION THAT AN EXCESSIVE HEAT WARNING COULD BE NEEDED. AT THIS TIME WE WILL KEEP MAX TEMPS BELOW WARNING THRESHOLDS...WITH 111 FORECAST AT PHOENIX. FOR MONDAY INTO THE MIDDLE OF NEXT WEEK...IT APPEARS THAT THE WESTERLIES WILL START TO STRENGTHEN THEIR GRIP ON THE WEATHER PATTERN ACROSS THE WESTERN UNITED STATES...AS AN INCREASING SWLY FLOW ALOFT SPREADS IN FROM THE WEST AND STARTS TO FLATTEN THE RIDGE AND SHIFT IT SOUTH AND EAST. H5 HEIGHTS GRADUALLY FALL ABOUT 40M FROM SUNDAY THROUGH WEDNESDAY...AND MAX TEMPS SHOULD TAPER OFF SLIGHTLY EACH DAY. ORIENTATION OF THE RIDGE...AS DEPICTED BY EITHER GFS OR EUROPEAN...IS NOT FAVORABLE FOR CONVECTION OVER OUR CWA. AS SUCH WE WILL KEEP POPS NEAR TO CLIMO...AND LIMITED TO THE HIGHER TERRAIN EAST OF PHOENIX EACH DAY. && .AVIATION... SOUTHEAST CALIFORNIA...SOUTHWEST AND SOUTH CENTRAL ARIZONA... INCLUDING KPHX...KIWA...KBLH...KIPL...AND KNYL AIRFIELDS. MOSTLY SUNNY TODAY WITH SOME MID-LEVEL CLOUDINESS OVER THE SOUTHWEST DESERTS...BETWEEN KBLH AND KPHX THIS MORNING. GENERALLY SUNNY SKIES WILL CONTINUE OVER THE REGION NEAR KIPL/KYUM/KBLH. SURFACE WINDS SLY THROUGHOUT THE DAY OVER SE CALIFORNIA AND ALONG PORTIONS OF THE LOWER COLORADO RIVER VALLEY...GENERALLY W-SWLY OVER THE CENTRAL DESERTS OF AZ WITH GUSTS UP TO 20KTS COMMON AT MOST SITES FROM 21Z THROUGH 03Z SATURDAY. THUNDERSTORM ACTIVITY WILL RE-EMERGE OVER THE HIGHER TERRAIN WELL TO THE EAST AND NORTH OF KPHX/KIWA AFTER 18Z...ACTIVITY PERSISTING THROUGH 05Z SATURDAY. AN ISOLATED STORM COULD FORM SOUTH-SOUTHEAST OF THE GREATER PHOENIX AREA AND MOVE SLOWLY TO THE N-NE...BUT FEEL STORMS WILL NOT BE CLOSE ENOUGH FOR GUSTY OUTFLOW WINDS TO AFFECT KIWA...EVEN A MORE REMOTE POSSIBILITY AT KPHX. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... SUFFICIENT MOISTURE EXPECTED TO REMAIN IN PLACE OVER EASTERN ARIZONA LEADING TO A SLIGHT CHANCE OF THUNDERSTORMS OVER THE HIGHER TERRAIN OF SOUTHERN GILA COUNTY EACH AFTERNOON/EVENING THROUGH THE WEEKEND INTO EARLY NEXT WEEK. STORMS WILL BE DRY...PRODUCING LITTLE PRECIPITATION...YET GENERATING STRONG GUSTY OUTFLOWS CAPABLE OF SPREADING INTO THE LOWER DESERTS. DRY AND HOT CONDITIONS PERSIST REGION-WIDE AS MINIMUM HUMIDITY LEVELS REMAIN IN THE SINGLE DIGITS TO LOWER TEENS...WITH ABOVE AVERAGE TEMPERATURES EXPECTED INTO EARLY NEXT WEEK. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT WEATHER.GOV/PHOENIX DISCUSSION...SAS/CB AVIATION...MEYERS FIRE WEATHER...MEYERS az AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1037 AM CDT FRI JUN 27 2008 .DISCUSSION... ISSUED 1036 AM CDT FRI JUN 27 2008 ANOTHER DAY WITH A VERY COMPLICATED MESOSCALE PATTERN ACROSS THE REGION. WIDESPREAD CONVECTION HAS MOSTLY SHIFTED EAST OF THE CWA... AHEAD OF MCV CENTERED NEAR KCMI. STILL SEEING SHOWERS ARCING BACK ACROSS DOUGLAS/MOULTRIE/MACON COUNTIES. MEANWHILE ANOTHER BATCH OF THUNDERSTORMS IS MOVING ACROSS SOUTHEASTERN ILLINOIS... AND WILL LIKELY MOVE INTO THE LAWRENCEVILLE AREA BETWEEN 11 AM AND NOON. ANOTHER MCV WAS CENTERED OVER NORTH/CENTRAL MISSOURI...WITH TRAILING BOUNDARY ARCING BACK INTO SOUTHEASTERN KANSAS. VISIBLE SATELLITE IMAGERY SHOWS NARROW CLEAR SLOT AND SFC OBS INDICATE DEWPOINTS IN THE LOWER 70S JUST AHEAD OF THIS FEATURE. RADAR TRENDS INDICATE A FEW NEW CONVECTIVE CELLS POPPING UP AHEAD OF THIS FEATURE AND ALONG THE BOUNDARY. WITH THE PARENT MCV MOVING NORTHEASTWARD... EXPECT THE ATTENDANT BOUNDARY TO DRAG ACROSS THE WESTERN HALF OF THE CWA. WILL UPDATE THE GRIDS AND ZONES TO REFLECT CURRENT TRENDS... BUT THIS WILL STILL RESULT IN A FRAGMENTED 1ST PERIOD AS THUNDERSTORM COMPLEX MOVING SOUTH OF I-70 AND SHOWERS INVOF EASTERN MCV WILL LIKELY PUSH OUT OF THE AREA BY 18-19Z. POST-18Z POP GRID STILL LOOKS TO BE IN GOOD SHAPE. SHOULD HAVE NEW PRODUCTS OUT BY 11 AM. HARDIMAN && .AVIATION... ISSUED 650 AM CDT FRI JUN 27 2008 SCATTERED THUNDERSTORMS CURRENTLY MOVING ACROSS THE PIA TAF SITE AND ARE NEAR SPI. THESE STORMS WILL ALSO GET CLOSE TO DEC...BMI AND CMI THIS MORNING SO HAVE INCLUDED VCTS IN ALL TAFS. WILL KEEP EARLIER TAFS SIMILAR WITH PROB30 T-STORMS DURING THE LATE AFTERNOON TO EARLY EVENING AT ALL SITES. QUESTION IS WHEN WILL MAIN FRONT PUSH THROUGH. MODELS INDICATE THAT THE FRONT WILL GET THROUGH A FEW OF OUR SITES AROUND 12Z SATURDAY...BUT DUE TO UNCERTAINTY WITH MODELS POOR HANDLING OF THIS SYSTEM AND OTHER PERIODS OF CONVECTION PAST SEVERAL DAYS...WILL NOT HAVE FROPA IN THIS SET OF TAFS. WILL PASS ON TO NEXT SHIFT. ALSO...WINDS WILL REMAIN SOUTHERLY TO SOUTHWESTERLY THROUGH THE PERIOD. VFR CONDITIONS WILL PREVAIL OUTSIDE THUNDERSTORMS. INSIDE STORMS...CAN EXPECT CIGS TO BE MVFR AND VIS TO BE IFR. AUTEN && .PREV DISCUSSION... ISSUED 330 AM CDT FRI JUN 27 2008 FORECAST CHALLENGES CONTINUE WITH SHORT RANGE MODELS NOT HANDLING MCS ACTIVITY VERY WELL DURING THE PAST FEW DAYS. BROKEN BAND OF CONVECTION QUICKLY FIRED UP DURING THE PAST HOUR FROM SE IA INTO WEST CENTRAL IL NEAR THE MS RIVER AND LIFTING ENE. RUC MODEL HINTED AT THIS SCENARIO THOUGH DEVELOPED QPF TOO QUICKLY. WILL ADDRESS CONVECTION CHANCES ALONG WITH SLIGHT RISK OF SEVERE STORMS THROUGH SAT AS COLD FRONT SLIDES SE THROUGH IL LATER TONIGHT AND INTO SAT. 08Z/3 AM SURFACE MAP SHOWS A FRONTAL BOUNDARY OVER SOUTHERN LOWER MI/WI/MN. MATURE MCS WAS OVER CENTRAL/EASTERN KY WITH WEAKER MCS OVER SW MN/EASTERN SD AND FAR NW IA. NEWLY DEVELOPED BROKEN LINE OF CONVECTION FROM SE IA INTO WEST CENTRAL IL AND ANOTHER AREA OF CONVECTION OVER SW IL SW OF MOUNT VERNON. CONVECTION IN WESTERN IL APPEARS TO BE TIED TO SW LOW LEVEL JET/WARM FRONT. MOIST DEWPOINTS IN THE MID 60S WHILE TEMPS IN THE UPPER 60S AND LOWER 70S WITH LIGHT SOUTH WINDS. ALOFT UPPER LEVEL HIGH PRESSURE WAS SPRAWLED ACROSS THE SOUTHERN STATES WITH UPPER LEVEL TROF/LOW OVER CANADA. SHORT WAVE TROF WAS OVER THE MID/UPPER MS VALLEY AND ALSO IN THE DAKOTAS. 553 DM 500 MB LOW WAS ALONG THE SOUTHERN ALBERTA AND SASKETCHEWAN BORDER AND DIGGING INTO THE NORTHERN PLAINS. SHORT TERM...TODAY THROUGH TUESDAY. INCREASED CHANCES OF SHOWERS AND THUNDERSTORMS TODAY TO LIKELY ALONG AND NW OF I-55 ESPECIALLY THIS MORNING WITH BROKEN LINE OF CONVECTION MOVING ENE INTO THE IL RIVER VALLEY. SOME OF THESE THUNDERSTORMS COULD BE STRONG ALONG WITH BRIEF HEAVY RAINS AND FREQUENT LIGHTNING. HAVE 30 TO 40% CHANCE OF SHOWERS AND THUNDERSTORMS ACORSS EAST CENTRAL AND SE IL TODAY. MOST SHORT RANGE MODELS SHOW A SHORT WAVE/MCV MOVING INTO IL FROM NE KS THIS AFTERNOON. THIS MOVING INTO AN UNSTABLE AIR MASS WITH PEAK HEATING THIS AFTERNOON SHOULD GENERATE SCATTERED CONVECTION. TONED DOWN HIGHS A BIT WITH MORE CLOUD COVER AND CONVECTION EXPECTED TODAY THAN EARLIER THOUGHT AS WAS THE CASE NW OF I-70 YESTERDAY. STILL VERY WARM AND HUMID WITH HIGHS IN THE UPPER 80S IN CENTRAL IL AND LOWER 90S SE IL FROM I-70 SE WITH DEWPOINTS AROUND 70F. COULD BE ISOLATED STRONG TO SEVERE THUNDERSTORMS THIS AFTERNOON WITH UNSTABLE AIR MASS AND ARRIVING MCV. BEST CHANCES OF CONVECTION WITH POSSIBLE SEVERE THUNDERSTORMS WILL ARRIVE TONIGHT AS A COLD FRONT MOVES SE TOWARD THE IA/IL BORDER BY MIDNIGHT AND TO I-55 BY 12Z/SAT. THIS DUE TO UPPER LEVEL TROF AMPLIFYING/DIGGING INTO THE UPPER MID WEST FROM SOUTHERN ALBERTA/SASKETCHEWAN. INCREASED POPS TO 80% NW OF I-70 TONIGHT. SPC CONTINUES SLIGHT RISK OF SEVERE STORMS ACROSS CENTRAL/SE IL TONIGHT. BEST CHANCE OF SEVERE STORMS WEST OF I-57 WITH 15 TO 30% SEVERE WIND GUSTS AND HAIL AND ISOLATED TORNADOES (2%). COLD FRONT COLLIDING WITH A VERY UNSTABLE AIR MASS WITH CAPES PEAKING FROM 2000 TO 3000 J/KG WEST OF I-57. BUT LIMITNG FACTORS FOR WIDESPREAD SEVERE STORMS IS UPPER LEVEL DYNAMICS AND BEST WIND FIELDS ARE NORTH OF CENTRAL IL. ALSO MORNING CONVECTION COULD LIMIT HEATING AND DESTABILIZATION OF ATMOSPHERE THIS AFTERNOON. ALSO CONCERN FOR HEAVY RAIN WITH PRECIPITABLE WATER VALUES OF 1.75 TO 2 INCHES. HAVE 0.75 TO 1.5 INCHES OF RAIN ACROSS AREA THROUGH TONIGHT WITH HIGHEST AMOUNTS OVER THE IL RIVER VALLEY. DID NOT ISSUE A FLASH FLOOD WATCH YET SINCE FLASH FLOOD GUIDANCE VALUES ARE 1.75 TO 2.5 INCHES PER HOUR...2 TO 3 INCHES PER 3 HOURS AND 2.5 TO 3.5 INCHES IN 6 HOURS. BUT ISOLATED AREAS IN THE IL RIVER VALLEY COULD SEE LOCAL 1.5 TO 3 INCH AMOUNTS TODAY AND TONIGHT SIMILAR TO WHAT HAPPENED TUE NIGHT. COLD FRONT SLIDE SE THROUGH SE IL SAT AND CONTINUES GOOD CHANCE OF CONVECTION IN EASTERN IL ESPECIALLY SAT MORNING AND MAINLY IN SE IL SAT AFTERNOON. SPC HAS SLIGHT RISK OF SEVERE STORMS SAT SE OF A CHAMPAIGN TO TAYLORVILLE LINE WITH BEST CHANCE SE OF A DANVILLE TO EFFINGHAM LINE WHERE CAPES PEAK FROM 1500 TO 2000 J/KG. A DRY WEDGE WORKS INTO CENTRAL IL DURING SAT BEHIND THE COLD FRONT WITH DEWPOINTS DROPPING THROUGH THE 60S WITH WEST BREEZES. COOLER HIGHS IN THE LOWER 80S CENTRAL IL AND MID 80S SE IL. SMALL CHANCE OF CONVECTION OVER SE IL UNTIL SUNSET SAT EVENING...OTHERWISE MOST AREAS WILL BE DRY SAT NIGHT. MODELS CONSISTENT IN BRINGING STRONG UPPER LEVEL LOW PRESSURE INTO NORTHERN MI SUNDAY AND TRENDING A BIT CLOUDIER...COOLER...BREEZIER AND BETTER CHANCES OF SHOWERS AND ISOLATED THUNDERSTORMS ESPECIALLY SUNDAY AFTERNOON UNTIL SUNSET SUNDAY EVENING. COOLED HIGHS A BIT INTO THE MID TO UPPER 70S AND INCREASED WNW WINDS TO BREEZIER LEVELS OF 15 TO 25 MPH. UPPER LEVEL LOW DRIFTS SLOWLY EAST INTO THE EASTERN GREAT LAKES BY TUE TAKING ITS SHOWERS EAST OF IL EARLY NEXT WORK WEEK. AREAS ALONG THE INDIANA BORDER COULD STILL SEE A RISK OF SHOWERS AND ISOLATED THUNDERSTORMS MON AFTERNOON. LONG TERM...TUESDAY NIGHT THROUGH THURSDAY. NO CHANGES MADE TO EXTENDED FORECAST WITH DRY WEATHER AND GRADUALLY MODIFYING TEMPERATURES TO NEAR OR A BIT ABOVE NORMAL AS UPPER LEVEL HEIGHTS RISE OVER IL BY MID WEEK. HIGHS WARM BACK INTO THE MID TO UPPER 80S WED AND THU AS HUMIDITY LEVELS INCREASE AS WELL. ECMWF SHOWING COLD FRONT AND QPF MOVING INTO IL THU. THIS IS A DAY SOONER THAN THE GFS AND DGEX MODELS WHEN IT BRINGS THIS INTO IL ON FRI. NO CHANGES MADE YET SINCE AWAITING BETTER MODEL AGREEMENT THAT FAR OUT. HUETTL && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 703 AM CDT FRI JUN 27 2008 .DISCUSSION... 339 AM CDT THE FIRST ISSUE IS THE THUNDERSTORMS THIS MORNING. THE 850 MB AND 700 MB PROFILER DATA SHOWS A SHORT WAVE TROUGH OVER SOUTH CENTRAL ILLINOIS. THE RADAR SHOWS SHOWERS AND THUNDERSTORMS MOVING INTO SOUTHWEST ILLINOIS. THOSE SHOWERS AND THUNDERSTORMS MAY REACH OUR FORECAST AREA OF NORTH CENTRAL ILLINOIS...NORTHEAST ILLINOIS AND NORTHWEST INDIANA BY THIS MORNING. THE JET STREAM WAS OVER NORTHERN WISCONSIN AND NORTHERN MINNESOTA AT 00 UTC. THERE IS A WEAK SURFACE FRONT OVER SOUTHERN WISCONSIN AND CENTRAL LAKE MICHIGAN. THUNDERSTORMS MAY FORM ALONG THIS FRONT LATER TODAY. THIS IS WHY WE WILL HAVE LIKELY THUNDERSTORMS FOR THE NORTHERN TWO THIRDS OF OUR FORECAST AREA. ANOTHER SHORT WAVE TROUGH MAY MOVE THROUGH NORTHERN ILLINOIS THIS MORNING. THE THUNDERSTORMS COULD PRODUCE HEAVY RAINFALL TODAY. DEPENDING ON THE RAINFALL FROM THE THUNDERSTORMS THIS MORNING WE MAY CONTEMPLATE A FLASH FLOOD WATCH LATER TODAY. WILL WAIT FOR NOW. THE DEVELOPING WAVE TROUGH OVER ALBERTA WILL BECOME LARGER AS IT MOVES INTO MINNESOTA SATURDAY MORNING. THIS TROUGH WILL MOVE INTO WISCONSIN BY SUNDAY. WE WILL HAVE THUNDERSTORMS LIKELY EARLY SATURDAY EVENING FOR THE NORTHWEST PORTION OF OUR WARNING. THEN RAIN AND ISOLATED THUNDERSTORMS SUNDAY FOR THE NORTH HALF OF OUR FORECAST AREA. MADE A FEW ADJUSTMENTS ON THE HIGH TEMPERATURES AND LOW TEMPERATURE FRIDAY THROUGH MONDAY. WE LOWER THEM A LITTLE AS WE HAVE FORECAST MORE CLOUDS. && .AVIATION... 702 AM CDT 12Z TAFORS...MCV MOVING ALONG THE MN-IA BORDER REVEALED BY TWIST IN ECHOES SEEN IN RADAR LOOP. EXTENDING TO THE SE ACROSS EASTERN IA AND WESTERN IL ARE MORE TS AS 35-45KT H8 JET PER PROFILER AND 88D NETS GENERATING GOOD ISENTROPIC LIFT. EASTWARD PROGRESSION OF TSRA HAS BEEN SLOWING WITH TIM. EXTRAPOLATION OF LATEST MOVEMENT HAS CONVECTION ARRIVING IN THE CHI VC AROUND 16Z. RUC SHOWS THE AREA OF UVV CONTINUING TO MOVE E BUT WEAKENING...AND HAS THE UVV EAST OF THE TERMINALS BY 18Z. WITH SLOWING AND SUGGESTED WEAKENING HAVE BROUGHT TSRA INTO KRFD 15-17Z BUT WITH ANTICIPATED WEAKENING ONLY HAVE SHRA INTO CHI TERMINALS. NEXT SHORT WAVE...CURRENTLY DROPPING SE ACROSS THE WESTERN DAKOTAS...TO CONTINUE SOUTHEASTWARD AND PROGGED TO REACH EASTERN MN...IA AND MO BY 00Z SAT. SHORT WAVE AND ASSOCIATED LOW LEVEL FORCING TO MOVE ACROSS TERMINALS LATE AFTERNOON AND THIS EVENING AS UPPER LOW DIGS SE FM SOUTHERN ALBERTA TO EASTERN ND. STRONG WAA IN LOWER LEVELS UNDER NEUTRAL TEMP ADVECTION IN MID LEVELS TO LEAD TO FURTHER DESTABILIZATION FOR TONIGHT. SHORT WAVE IS LIFTED NE THRU THE UPPER MIDWEST AND THE WESTERN GREAT LAKES OVERNIGHT AS THE UPPER CIRCULATION CROSSES OVER MN. THIS TO PUSH A COLD FRONT W TO E ACROSS THE TERMINALS IN 08-12Z WINDOW. TRS && .MARINE... 305 AM CDT LOW PRESSURE WILL MOVE NE ACROSS THE UPPER MS VALLEY TODAY AND TO NEAR LK SUPERIOR OVERNIGHT. AS IT DOES A WARM FRONT LIFTS N TO NORTHERN LK MI BY LATE EVENING...THEN A COLD FRONT SWINGS E ACROSS LAKE MICHIGAN SAT MORNING. STABLE AIR-WATER INTERFACE WITH VERY WARM AIR OVER COOL WATER AND WEAK PRES GRADIENT KEEPS WINDS PRETTY LIGHT TODAY. COLD FRONT TO PUSH EAST ACROSS THE LAKE SAT. TIGHTER GRADIENT BUT STILL WARM AIR SO WINDS NOT EXPECTED TO INCREASE APPRECIABLY UNTIL TROF/SECONDARY COLD FRONT ROTATES THRU THE WESTERN GRTLKS DURING SUN. TRS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 1006 AM EDT FRI JUN 27 2008 .SHORT TERM.../THE REST OF TODAY/...UPDATED VERY LITTLE ADJUSTMENT IN FORECAST IS NECESSARY. RUC HAS A NICE HANDLE ON SHORTWAVES THOUGH IT APPEARS OVERDONE FOR CAPE IN SOUNDINGS. CURRENT CONVECTION OVER EXTREME SOUTHEAST KY DEVELOPED IN AN AREA OF 2000 J/KG FROM 925-850 MB LAYER (IN RUC...IN NAM THAT AREA IS SOUTH OF KY) AND AIDED BY THKJKLNOWJKLE TAIL END OF A VORT. A WEAKER WAVE IS MOVING INTO CENTRAL KY. STRONGER SHORTWAVES OVER MO/IL MIGHT AFFECT AREA TONIGHT. IN ADDITION THE RUC SHOWS SOME DECENT 250 MB DIVERGENCE TO AID CONVECTION ABOUT 21Z THIS AFTERNOON THEN EXPECT ITS CONVERGENT COUPLET TO HELP END IT BY 28/00Z. ATTM...THINK SCATTERED STORMS ARE A GIVEN THIS AFTERNOON AND A FEW OF THEM GETTING SEVERE ARE LIKELY. DON/T THINK THE CLOUDS ARE GOING TO KEEP TEMPERATURES DOWN MUCH FROM YESTERDAYS LEVELS. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /TODAY THROUGH SUNDAY NIGHT/ 06Z SFC ANALYSIS SHOWS WANING HIGH PRESSURE OVER THE SOUTHEAST PORTION OF THE NATION WHILE A WAVY WARM FRONT IS LAYING ACROSS THE SOUTHERN GREAT LAKES RUNNING EAST FROM A LOW PRESSURE CENTER OVER THE UPPER MIDWEST. EACH DAY THE UPPER RIDGE HAS BROKEN DOWN A BIT MORE SO THAT A BAND OF SHOWERS AND THUNDERSTORMS WERE ABLE TO PUSH INTO THE WESTERN PORTION OF THE CWA THIS PAST EVENING. WHILE THESE INITIAL STORMS HAVE STALLED AND DISSIPATED...THEY LEFT BEHIND A BOUNDARY THAT CONTINUES TO SHOW SIGNS OF ACTIVITY...JUST TO THE NORTHWEST OF JKL. A LARGE FACTOR IN THE ABILITY OF THESE STORMS TO SETTLE DEEPER INTO OUR REGION THAN PREVIOUS DAYS IS THE PRESENCE OF A WELL DEFINED MCV CURRENTLY CUTTING ACROSS CENTRAL OHIO. THE SKY COVER MIRRORS THE RADAR IMAGES WITH LOWER AND THICKER CLOUDS OVER THE WESTERN PORTION OF THE STATE AND MAINLY RESIDUAL MID LEVEL CLOUDS FOUND OVER THE EAST. TEMPERATURES OVER THE AREA ARE RUNNING FROM THE MID 60S IN THE VALLEYS TO THE LOWER 70S ON THE RIDGES WHILE DEWPOINTS ARE UP IN THE MIDDLE 60S THROUGH MOST OF THE AREA. THE MODELS ARE IN FAIRLY GOOD AGREEMENT ALOFT WITH AN UNSEASONABLY STRONG...CLOSED UPPER LOW RIDING EAST SOUTHEAST THROUGH THE UPPER MIDWEST AND INTO THE NORTHERN OHIO VALLEY ON SATURDAY. THIS HIGHLY AMPLIFIED FEATURE THEN SPINS INTO A DEEP LOW OVER THE GREAT LAKES FOR SUNDAY...MAINTAINING IMPRESSIVE TROUGHING OVER THE OHIO VALLEY RIGHT INTO THE BEGINNING OF THE NEW WORK WEEK. THE MODELS MATCH UP QUITE WELL THROUGH SATURDAY BEFORE THE 12Z ECMWF AND 00Z GFS PULL THE LOW NORTHEAST A TAD QUICKER THAN THE LATEST NAM. NEVERTHELESS... PREFER THE NAM/S ATTEMPT AT FORECASTING THE VARIOUS SHORTWAVES... SYNOPTIC AND CONVECTIVELY INDUCED...RESPONSIBLE FOR THIS PATTERN EVOLUTION. IN GENERAL...THE SPECIFICS OF THE NAM12 WERE FOLLOWED THROUGH 84 HOURS. SENSIBLE WEATHER FOR EASTERN KENTUCKY WILL BE DRIVEN BY THE BUILDUP OF INSTABILITY AND MOISTURE THROUGH THE LOWER OHIO VALLEY IN A BROAD PRE-FRONTAL WARM SECTOR TODAY AND INTO SATURDAY. THE UNDERLYING CONDITIONS FOR CONVECTION...WHILE HEAVILY INFLUENCED BY THE DIURNAL CYCLE OF INSTABILITY...WILL BE FURTHER ENHANCED BY THE PRESENCE OF SFC BOUNDARIES AND PROPAGATING DOWNSTREAM MCVS. ACCORDINGLY...HAVE ATTEMPTED TO DRAW THE POP...AND IN A SIMILAR MANNER SKY...GRIDS BASED ON AN EXTRAPOLATION OF CURRENT ACTIVITY...LATEST SHORT RANGE GUIDANCE FROM THE NAM12 AND A STRONG DIURNAL COMPONENT. THIS MUDDLED FORECAST SITUATION FOR TODAY AND TONIGHT BECOMES MORE CLEAR ON SATURDAY WHEN A WELL MODELED COLD FRONT WILL BE ENTERING INTO AND CROSSING THE AREA LATER IN THE DAY. THIS FRONT WILL ALSO HAVE THE UPPER SUPPORT OF A STRENGTHENING MID LEVEL WIND FIELD IN ACCORDANCE WITH THE CLOSE APPROACH OF THE UPPER LOW. IN CONJUNCTION WITH AN ALREADY QUITE MOIST AIR COLUMN OVER THE REGION...THE UPPER DYNAMICS WILL YIELD THE BEST SHOT FOR ORGANIZED AND POTENTIALLY SEVERE CONVECTION WITH THE MAIN THREATS BEING DAMAGING WIND GUSTS AND ISOLATED LARGE HAIL. IN ADDITION...THE STORMS OF THE SHORT TERM PERIOD SHOULD BE EFFICIENT PRECIPITATION PRODUCERS RAISING THE POTENTIAL FOR LOCALIZED EXCESSIVE RAINFALL...HOWEVER THE ANTECEDENT CONDITIONS WILL MAKE THIS LESS OF A CONCERN THAN NORMAL...ALTHOUGH WHAT IS NORMAL IN THE GOING ON TWO YEARS OF DROUGHT OR NEAR DROUGHT ACROSS THE AREA. INTERPRETING THE PREFERRED NAM SOLUTION FOR SFC FEATURES AND RESULTING WX...WILL BRING THE COLD FRONT EAST THROUGH THE CWA SATURDAY NIGHT AND SLOWLY CLEAR THE POPS OUT WEST TO EAST ON SUNDAY...THOUGH HELD THEM RELATIVELY STEADY FOR A TIME AT PEAK HEATING AND DURING A TIME OF INCREASING MID LEVEL LAPSE RATES SUNDAY AFTERNOON. OUR PROXIMITY TO THE UPPER LOW CENTER SUNDAY NIGHT WILL KEEP THE THREAT OF CONVECTION CONTINUING INTO MONDAY MORNING... ESPECIALLY ACROSS OUR NORTHERN COUNTIES. DESPITE PREFERRING THE MET/S PARENT MODEL...ACTUALLY SAW THE MAV TEMPERATURE NUMBERS AS MORE REASONABLE THROUGH THE WEEKEND. AS FOR POPS DID END UP CLOSEST TO THE MET ONES. .LONG TERM.../MONDAY THROUGH THURSDAY/ ENSEMBLES AND OPERATIONAL RUNS SREF/GFS/ECMWF/CANADIAN/NOGAPS AGREE FAIRLY WELL REGARDING THE UNUSUALLY HIGH AMPLITUDE (FOR JULY) AND POSITION OF SHORTWAVE TROUGH SWEEPING THROUGH EASTERN U.S. LATE THIS WEEKEND AND THEN BUILDING THE RIDGE AGAIN. HPC GUIDANCE WAS CONSISTENT WITH THIS IDEA AND HELD ON TO IT. MODELS HAVE BEEN SLOWING PROGRESSION OF THAT SHORTWAVE DOWN AND WE MAY BE HOLDING ONTO AND/OR EXTENDING RAIN CHANCES SUN/MON (MEX SHOWS CATEGORICAL POPS ON SUN). BY WED THE PATTERN LOOKS SIMILAR TO CURRENT CONDITIONS AND A RETURN TO HOT/HUMID IS LIKELY BY THEN. && .AVIATION.../12Z TO 12Z/ WITH A HUMID AND UNSTABLE AIR MASS ACROSS THE AREA...EXPECT SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP LATER THIS MORNING AND THIS AFTERNOON. WILL CONTINUE TO USE VCTS IN THE TAFS FOR THIS SCENARIO...SINCE EXACT LOCATION AND TIMING OF TS TOO FAR IN ADVANCE IN THIS SITUATION IS DIFFICULT. TAFS WILL BE AMENDED IF IT APPEARS A TS WILL AFFECT A PARTICULAR TAF SITE. EXPECTING MAINLY VFR CONDITIONS THROUGH MOST OF THE TAF PERIOD...HOWEVER BRIEF IFR CONDITIONS ARE EXPECTED IN INDIVIDUAL TS. TS ACTIVITY SHOULD BEGIN TO DECREASE AFTER SUNSET. COULD SEE AN INCREASE IN ACTIVITY AGAIN TOWARDS THE END OF THE TAF PERIOD WITH THE POSSIBILITY OF A THUNDERSTORM COMPLEX JUST NORTH OF THE AREA. WILL CONTINUE TO MONITOR THE TRACK OF THIS FOR LATER FORECASTS. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...GREIF/GV LONG TERM....GV AVIATION...WJM ky AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MARQUETTE MI 1106 AM EDT FRI JUN 27 2008 .SYNOPSIS... WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED A FEW SHRTWVS OF INTEREST FOR THE SHORT TERM...BOTH PRODUCING SOME SHOWERS AND THUNDERSTORMS. THE FIRST IS IN NORTH CENTRAL MN...WITH THE KDLH RADAR DEPICTING SCATTERED -TSRA TO THE WEST AND NW OF DULUTH. THE SECOND IS BACK IN THE DAKOTAS...WITH ACTUALLY A LARGE AREA OF SHOWERS AND EMBEDDED TSRA BETWEEN PIERRE AND ABERDEEN. UPPER MI CURRENTLY UNDER UPPER LEVEL RIDGING...BEING BUILT UP AHEAD OF THE MN SHRTWV AND THE STRONGER UPPER LOW DIGGING DOWN OUT OF SASKATCHEWAN. THIS UPPER RIDGING IS HELPING TO KEEP SKIES PARTLY CLOUDY OVER THE CWA...WITH THE EXCEPTION OF THE FAR WESTERN U.P. WHERE HIGH CLOUDS ARE ENCROACHING. 14Z TAMDAR SOUNDING FROM SAW AND 12Z RAOB FROM GRB DEPICT THE UPPER RIDGE WITH A SUBSIDENCE INVERSION/CAP AROUND 750MB. DRY AIR EVIDENT AS WELL BOTH AT AND BELOW THIS INVERSION...WITH THE GRB SOUNDING SHOWING 925MB DEWPOINT DEPRESSION OF 8C. OTHER ITEM TO NOTE IS THE PERSISTENT FOG OVER LAKE SUPERIOR. SHIP OB JUST CAME IN ABOUT 10 MILES NORTH OF GRAND MARAIS AND SHOWED 1/8SM VSBY. && .UPDATE... TRICKY FORECAST FOR THE AFTERNOON TRYING TO FORECAST TSRA DEVELOPMENT. WITH THE 12Z GRB SOUNDING SHOWING CAPPING AND DRY AIR...AND THE FACT THAT 500MB HEIGHTS DO NOT FALL MUCH TODAY (LIKELY INDICATING CAPPING TO STAY IN PLACE)...THINKING IS AT LEAST THE CENTRAL U.P. WILL NOT SEE MUCH IF ANY PCPN BEFORE 00Z. THE 12Z RUC AGREES WITH THIS ASSESSMENT...WITH SOUNDINGS AT IMT...MQT AND ERY CAPPED WITH TOO MUCH CIN TO OVERCOME (AIDED BY DAYTIME MIXING BRINGING DRIER AIR TO THE SURFACE). THE ONLY PLACE THAT LOOKS GOOD FOR PCPN TO FORM IS IN THE WESTERN U.P....ASSUMING THE HIGH CLOUDS THIN OUT SOME WHICH APPEARS TO BE HAPPENING IN THE LATEST VISIBLE SATELLITE IMAGES. AIRMASS THERE IS A BIT MORE MOIST OVERALL...WHICH SHOULD HOLD THE DEWPOINTS UP. WITH TEMPS GETTING INTO THE MID TO PERHAPS UPPER 70S...AND HEIGHT FALLS APPROACHING LATER IN THE DAY ASSOCIATED WITH THE MN SHRTWV (HELPING TO ELIMINATE CAPPING)... MLCAPES SHOULD APPROACH CLOSE TO 1000 J/KG. THEREFORE...FOR THIS AFTN...MAINTAINED 70 POPS OUT IN THE WEST...AND LOWERED TO 20 IN THE NORTH CENTRAL AND EAST. SVR WX POTENTIAL NOT TOO GREAT...GIVEN 0-6KM SHEAR VALUES BELOW 30 KNOTS. REGARDING THE FOG ON LAKE SUPERIOR...ADJUSTED IT A BIT BASED ON WIND DIRECTION FORECASTS...WHICH SEEM TO MOSTLY FAVOR THE EAST SIDE OF THE KEWEENAW BEING IMPACTED WITH EAST WINDS PICKING UP. ADJUSTED TEMPS SLIGHTLY ALONG THE SHORES BASED ON WIND DIRECTIONS...WITH THE GRAND TRAVERSE BAY SITE ON THE EAST SIDE OF THE KEWEENAW REPORTING 57...BIG BAY AT 61 AND GRAND MARAIS AT 54. ALL THREE SITES SHOULD SEE ONSHORE WIND CONDITIONS THROUGH THE DAY...THUS LOWERED HIGHS AT ALL THREE AREAS. WILL NEED TO ADJUST POPS AFTER 00Z TO DELAY PCPN MOVING INTO THE EASTERN U.P.. STILL THINK THE 70 POPS FOR TONIGHT LOOK GOOD...WITH THE NEXT SHRTWV IN THE DAKOTAS MOVING INTO THE CWA...ALONG WITH ITS ASSOCIATED SHRA AND TSRA. && .DISCUSSION... KIND OF A MESSY PATTERN ACROSS NORTH AMERICA. STRONGEST FEATURE OF NOTE IS A STRONG 500 MB TROUGH ACROSS ALBERTA AND WESTERN SASKATCHEWAN WHICH SHOWS UP AS STRONG DARKENING AND STRONG CYCLONIC ROTATION ON WATER VAPOR. THERE ARE NUMEROUS WEAK SHORTWAVES THAT WERE EITHER CAUSING CONVECTION OR WERE CONVECTIVELY INDUCED ACROSS THE PLAINS AND OHIO RIVER VALLEY. THE NAM TAKES THE TROUGH ACROSS THE CANADIAN ROCKIES AND DIGS IT SOUTHEAST AND FORMS A CLOSED 500 MB LOW WITH IT ACROSS THE CANADIAN PRAIRIES WITH THE TROUGH INTO THE NORTHERN PLAINS 00Z SAT. THE NAM THEN BRINGS THE CLOSED 500 MB LOW INTO THE WESTERN U.P. 00Z SUN AND THEN SLOWLY MOVES IT EAST TO NEAR SAULT STE MARIE 00Z MON AND THEN INTO EASTERN ONTARIO. MEANWHILE...THE NAM BUILDS A STRONG 500 MB RIDGE INTO THE WESTERN U.S. NAM BRINGS IN SOME 850-500 MB Q-VECTOR CONVERGENCE THIS AFTERNOON ACROSS THE WEST HALF WITH PLENTY OF MOISTURE AND Q-VECTOR CONVERGENCE TONIGHT. NAM THEN SHOWS A DRY SLOT MOVING INTO THE AREA ON SAT WITH DYNAMICS DEPARTING AS WELL AS THE CLOSED 500 MB LOW COMES INTO THE AREA. NAM THEN BRINGS BACK IN MOISTURE WITH WRAPAROUND MOISTURE MOVING IN FOR SAT NIGHT AND SUN WITH THE MOISTURE STARTING TO MOVE OUT ON MON. NAM SHOWING SOME ISENTROPIC LIFT ON I300K-I315K SURFACES WITH MOISTURE TONIGHT AND THE MOISTURE MOVES OUT WITH LIFT MOVING OUT ON SAT. GFS IS SIMILAR TO THE NAM AND WILL USE A BLEND OF THE TWO FOR THIS FORECAST. WILL NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST AS CONFIDENCE IN TIMING IS PRETTY LOW ESPECIALLY WITH ANY SHORTWAVE PASSAGE. WILL HAVE LIKELY POPS THIS AFTERNOON AND TONIGHT WITH BEST DYNAMICS MOVING THROUGH ALONG WITH MOISTURE. HAIL LOOKS POSSIBLE ALONG WITH GUSTY WINDS OUT OF ANY THUNDERSTORMS IN THE DRY SLOT SATURDAY AFTERNOON AND ADDED INTO THE FORECAST WITH STEEP LAPSE RATES ACROSS THE AREA. ANY SUNSHINE WILL HELP STRENGTHEN ANY CONVECTION THAT FORMS. DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST EXCEPT LOWERED HIGHS A BIT ON SUNDAY WITH THE UPPER LEVEL LOW IN THE AREA AND COLDER TEMPERATURES ALOFT WHICH WILL DROP TEMPERATURES A BIT AT THE SFC EVEN WITH SOME MIXING. OVERALL...GOING FORECAST WAS GOOD AND MADE VERY FEW CHANGES. FOG WILL CONTINUE OVER LAKE SUPERIOR THROUGH TONIGHT AT LEAST. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... THE WINDS WILL BE JUST STRONG ENOUGH PUSH FOG/STRATUS UP THE HILL TO KCMX. EASTERLY FLOW TODAY SHOULD LOCK IN MVFR CIGS AT KCMX WITH POTENTIAL OF LATE AFTN SHRA/TSRA AS SYSTEM APPROACHES FROM THE WEST. CONDITIONS WILL LIKELY DETERIORATE TO IFR FRI EVENING UNDER UPSLOPING MOIST EAST FLOW. AT KSAW...VFR CONDITIONS SHOULD BE THE RULE FOR MUCH THROUGH TODAY WITH ANY SHRA/TSRA PROBABLY HOLDING OFF TIL LATE AFTERNOON OR EVENING. MVFR CONDITIONS POSSIBLE WITH PRECIPITATION. LOW LEVEL MOISTURE WILL INCREASE AND WITH SURFACE BASE INVERSION SETTING UP OVERNIGHT...EXPECT TO SEE DENSE FOG IN THE MORNING AT BOTH LOCATIONS. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... AS HIGH PRESSURE CROSSES LAKE SUPERIOR TODAY WINDS WILL BE LESS THAN 20 KNOTS. AS ANOTHER LOW PRESSURE TROUGH WILL MOVE INTO LAKE SUPERIOR ON TONIGHT AND SATURDAY...PRESSURE GRADIENTS WILL TIGHTEN CAUSING WINDS TO INCREASE TO 20 TO 25 KNOTS FOR A PERIOD OVER CENTRAL AND EAST EASTERN LAKE SUPERIOR. BY LATE SUNDAY NIGHT...THE LOW FILLING SLIGHTLY AND SLIDE SOUTHEASTWARD OVER LOWER MICHIGAN CAUSING THE WINDS TO BE LESS AN 20 KNOTS FOR THE REMAINDER OF THE PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/UPDATE...AJ DISCUSSION...GM AVIATION...DLG MARINE...DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 651 AM CDT FRI JUN 27 2008 .UPDATE... UPDATED FOR AVIATION DISCUSSION BELOW. && .DISCUSSION... /ISSUED 301 AM CDT FRI JUN 27 2008/ FORECAST CONCERNS CENTERED ON THUNDERSTORM POTENTIAL TODAY AND INTO TONIGHT...WITH SEVERITY ALSO AN ISSUE. MESSY SURFACE PATTERN OVER THE REGION AT PRESENT...DUE TO THE INFLUENCES OF MCS ACTIVITY. MAIN SURFACE TROUGH/COLD FRONT LOOKS TO EXTEND SOUTHWARD THROUGH THE CENTRAL DAKOTAS. WATER VAPOR IMAGERY SHOWS THE MAIN PLAYER IN OUR WEATHER OVER THE NEXT COUPLE OF DAYS...AN UPPER LEVEL LOW ALONG THE ALBERTA/SASKATCHEWAN BORDER...DROPPING SOUTHEASTWARD TOWARD THE AREA. REGION OF CONVECTION STRETCHES ALL ALONG THE WESTERN BORDER OF MINNESOTA...WITH MOST ENERGETIC STORMS VERY NEAR THE FORECAST AREA...IN SOUTHWEST MINNESOTA. THE AFOREMENTIONED REGION OF THE STORMS WILL CONTINUE TO MOVE EASTWARD DURING THE MORNING HOURS. THE COLD FRONT WILL ALSO MAKE EASTWARD PROGRESS THROUGH THE FORECAST AREA AS THE AFOREMENTIONED UPPER LEVEL LOW DROPS TOWARD THE DAKOTAS. WITH SEVERAL UPPER LEVEL VORTICITY CENTERS FLOATING AROUND /LARGELY CONVECTIVELY INDUCED/ ADDITIONAL THUNDERSTORM DEVELOPMENT WILL BE LIKELY THIS AFTERNOON AND EVENING OVER THE EASTERN HALF OF THE FORECAST AREA. FORECAST MUCAPES OF 2 KJ/KG EXIST OVER FAR EAST CENTRAL MINNESOTA AND WEST CENTRAL WISCONSIN DURING THE LATE AFTERNOON AND EVENING...AND WITH SUFFICIENT DEEP LAYER SHEAR...SEVERE WEATHER IS A POSSIBILITY. THE TORNADO THREAT WILL HINGE ON HOW THE CLOUD COVER FROM THIS MORNINGS ACTIVITY AFFECTS THE SURFACE BASED INSTABILITIES...AS WELL AS HOW MUCH OF AN AFFECT THE CONVECTION OVER THE CENTRAL PLAINS AND MID MISSISSIPPI VALLEY HAS. ANOTHER SHORTWAVE WILL SWING INTO WESTERN MINNESOTA THIS AFTERNOON AND EVENING...IN THE COLDER AIR...WHICH COULD GENERATE ANOTHER ROUND OF SCATTERED STORMS IN THAT AREA. THE UPPER LOW WILL SWING INTO CENTRAL MINNESOTA BY SATURDAY MORNING...WHICH COULD SPELL TROUBLE FOR SATURDAY AFTERNOON. CERTAINLY ADDITIONAL CONVECTION WILL DEVELOP DURING THE AFTERNOON HOURS BENEATH THE COLD CORE ALOFT...BUT WHAT MAY BE AN ISSUE IS NON SUPERCELL TORNADOES. AT THIS TIME...IT APPEARS THE UPPER LOW MAY BE ARRIVING IN THE AREA AT JUST THE RIGHT TIME OF DAY TO PREVENT THIS OVER MUCH OF MINNESOTA...AND POSSIBLY WESTERN WISCONSIN...BUT IT CERTAINLY BEARS WATCHING CLOSELY...ESPECIALLY IN WISCONSIN. THE UPPER LOW WILL CONTINUE TO PULL AWAY FROM THE REGION DURING THE LATTER PART OF THE WEEKEND...WITH THE CHANCE OF PRECIPITATION BEING LARGELY GONE FROM MINNESOTA AND WISCONSIN FOR A COUPLE OF DAYS BY SUNDAY NIGHT AND MONDAY...AS AN AMPLIFIED UPPER RIDGE TAKES THE LOWS PLACE. && .AVIATION.../12Z TAF ISSUANCE/ ONE BATCH OF SHOWERS AND STORMS HAVE BEEN SLIDING EWD ACROSS FAR SOUTHERN MN...SOUTH OF TAF SITES. MEANWHILE SHOWERS HAVE BEEN WEAKENING AS THEY MOVE INTO CENTRAL OR EAST CENTRAL MN. RUC AND OTHER MODELS HAD INDICATED DURING THE OVERNIGHT HOURS THAT SUCH A SCENARIO WAS LIKELY...WITH DRY AIR ENTRENCHED OVER THIS AREA. BACKED OFF ON THE CHC OF RAIN UNTIL THIS AFTERNOON WHEN FRONT AND TROUGH HELP SET OFF SOME STORMS. SUSPECT THERE WILL BE ONE AREA OF STORMS DEVELOPING MID AFTERNOON ALONG TROUGH LINE IN FAR EASTERN MN OR WRN WISC...AND ANOTHER DEVELOPING IN CENTRAL MN ALONG FRONT. GUSTY WNW WINDS AFTER FRONT. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ KAT/TDK mn AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE JACKSON MS 1045 AM CDT FRI JUN 27 2008 .DISCUSSION...COULD BE ANOTHER INTERESTING DAY TODAY FOR CONVECTION. WITH THE LACK OF WIDESPREAD CONVECTION YESTERDAY THE ATMOSPHERE REALLY DIDN`T GET WORKED OVER TOO MUCH. MOISTURE IS SLIGHTLY BETTER THAN YESTERDAY AS WELL...ESPECIALLY IN THE LOWER LEVELS WHERE IT LOOKS LIKE DEWPOINTS WILL LIKELY REMAIN IN THE UPPER 60S(INSTEAD OF DROPPING INTO THE MID TO LOWER 60S LIKE YESTERDAY). TEMPERATURES ARE WARMING UP FAST WITH MID 80S ALREADY ACROSS MOST OF THE AREA. WV SHOWS AND AREA OF LIFT/ENHANCEMENT OVER CNTRL MS AND THIS COULD COME INTO PLAY PRETTY SOON. ALSO THE RUC IS SHOWING SOME COLD POCKETS WORKING SOUTH INTO THE CWA. THIS IS HAVING AN EFFECT ON THE AREA AS IT IS KEEPING OUR LAPSE RATES FROM IMPROVING LIKE PREVIOUSLY THOUGHT. LOCAL SNDGS SHOW VT AGAIN IN THE 27-28 RANGE ACROSS MOST OF THE ARKLAMISS AND THIS IS STILL PRETTY GOOD. WET MICROBURST CHECKLIST ONCE AGAIN SHOWS A DECENT RISK FOR STRONG TO SEVERE STORMS ESPECIALLY ALONG AND NORTH OF I 20. THE SOUTH LAPSE RATES WILL NOT BE QUITE AS STEEP AND CONVECTION MAY FIRE A LITTLE TOO QUICKLY WHICH WOULD HURT OVER ALL INSTABILITY AS THIS AREA WOULD NOT BE ABLE TO WARM TO POTENTIAL. ONCE AGAIN THE UPPER LEVEL FEATURES ARE QUITE SUBTLE AND WITH NO REAL FLOW TO TALK ABOUT IN THE MID LEVELS CONVECTION WILL BE SOLELY DEPENDANT ON MESOSCALE FEATURES I.E. OLD BOUNDARIES FROM YESTERDAY AND NEW OUTFLOW BOUNDARIES FROM STORMS TODAY. OVERALL SCT CONVECTION ACROSS THE NORTH AND WIDESPREAD CONVECTION IN THE SOUTH LOOKS TO BE CASE WITH ISLTD TO SCT STRONG STORMS AND SOME OF THOSE REACHING SEVERE LIMITS THIS AFTERNOON AND INTO THE EARLY EVENING HOURS. UPDATED ZFP AND GRIDS WILL BE OUT SHORTLY ALTHOUGH THE CURRENT FORECAST IS HANDLING THINGS QUITE WELL AS WE SPEAK. && .AVIATION...VFR CONDITIONS WILL PERSIST UNTIL CONVECTION STARTS. ONCE THAT OCCURS STORMS WILL CAUSE CEILINGS TO TEMPORARILY DROP INTO MVR STATUS WITH VISBIES FALLING INTO IFR STATUS. STRONG WINDS WILL BE POSSIBLE FROM STORMS ALONG WITH SOME SMALL HAIL(BUT THE HAIL RICK IS NOT NEARLY SIGNIFICANT ENOUGH TO MENTION IN THE TAFS AT THIS TIME). CONVECTION SHOULD ONCE AGAIN CALM DOWN QUICKLY AFTER SUNSET WITH VFR CONDITIONS TAKING OVER ONCE AGAIN. AFTER THAT SOME LOW CLOUDS OR FOG MAY BE AN ISSUE DURING THE EARLY MORNING HOURS BUT THAT IS STILL UP IN THE AIR...ESPECIALLY SINCE THIS HAS HAD A HARD TIME MATERIALIZING THE LAST FEW NIGHTS. /BB/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 91 72 91 71 / 46 16 25 23 MERIDIAN 91 70 90 70 / 54 21 26 25 VICKSBURG 91 73 92 72 / 37 13 25 22 HATTIESBURG 89 71 91 71 / 66 21 45 23 NATCHEZ 88 71 89 71 / 56 16 45 19 GREENVILLE 93 73 93 71 / 23 12 26 45 GREENWOOD 92 72 92 72 / 25 14 26 45 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ CAB ms AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GRAND FORKS ND 1048 AM CDT FRI JUN 27 2008 .DISCUSSION... MAIN FORECAST CHALLENGE IS PRECIPITATION. WHEN LOOKING AT THE LATEST SURFACE ANALYSIS...AN AREA OF LOW PRESSURE IS CENTERED NEAR DTL WITH AN INVERTED TROF EXTENDING THROUGH NW MN ALONG A TVF-ROX LINE. KMVX SHOWS RESIDUAL CONVECTION OVER CENTRAL ND AND PARTS OF NW AND WC MN. WHEN COMPARING THE MODELS...THE MODELS CONTINUE IN PRETTY GOOD AGREEMENT...SO USED MODEL COMPROMISE FOR FORECAST. WITH SOME LINGERING CONVECTION AND LITTLE CAP EVIDENT ON MODEL SOUNDINGS TODAY...NOT EXPECTING A VERY LONG LULL IN CONVECTIVE ACTIVITY TODAY. MODELS HAVE SURFACED BASED CAPE UP TO 2000 BY 18Z AND MORE LOW LEVEL MOISTURE AVAILABLE THAN WE HAVE SEEN SO FAR THIS YEAR...WITH THE COLD CORE 500MB LOW STARTING TO MOVE TOWARDS ND. THUS...ANTICIPATE THAT THE STORMS WHICH DO DEVELOP COULD BECOME SEVERE WITH LARGE HAIL AND DAMAGING WINDS BEING THE MAIN SEVERE WEATHER THREATS FROM THIS AFTERNOON INTO THIS EVENING. THEREFORE... CUT BACK A BIT ON POPS FOR THE REMAINDER OF THIS MORNING...AND THEN PUSHED THE LIKELY AREA BACK TOWARDS THE RED RIVER VALLEY THIS AFTERNOON... DUE TO A LITTLE SLOWER SYSTEM TIMING. OTHERWISE...REST OF FORECAST IN PRETTY GOOD SHAPE WITH ONLY MINOR CHANGES NEEDED. && .AVIATION... PATCHES OF MVFR/IFR CIGS AND REDUCED VSBYS EXPECTED TO CONTINUE TODAY IN CONJUNCTION WITH SHRA/TSRA ACTIVITY...WHICH SHOULD BECOME MORE WIDESPREAD THIS AFTERNOON. WINDS TO TURN MORE NW AND BECOME GUSTY...WITH GUSTS UP TO 25 KTS POSSIBLE IN THE VALLEY BY 20Z. && .PREV DISCUSSION... /ISSUED 430 AM CDT FRI JUN 27 2008/ DISCUSSION...TODAY THROUGH SUNDAY NIGHT. UPPER LEVEL SYSTEM WILL DIG INTO THE N PLAINS TODAY. WATER VAPOR LOOP SHOWS CIRCULATION CENTER OVER N AB/SK BORDER WITH SHORT WAVE OVER THE S AB/SK BORDER. SHORT WAVE WAS DIGGING SE ABOUT 35 KNOTS. COLD FRONT OVER NW ND WILL MOVE THROUGH THE AREA THIS AFTERNOON. MESOSCALE ANALYSIS SHOWS BEST PRESSURE FALLS WERE OVER SE ND. E-W LOW LEVEL THETA-E GRAD WAS OVER E ND. RUC MAINTAINS PRESSURE FALLS OVER FORECAST AREA THIS MORNING. PRESSURE RISE CENTER OVER MT/SK/AB BORDER MOVES INTO THE W DAKOTAS LATER THIS MORNING WITH COLD FRONT MOVING IN. AREA VAD WINDS INDICATE FLOW ABOVE 850 HPA WAS OUT OF THE W WHILE BELOW 850 HPA THE FLOW WAS S OR SE. NO MODEL HANDLED THE FLOW VERY WELL BELOW 850 HPA. BEST INSTABILITY WAS OVER NW MN AND INTO SE ND. THUNDERSTORMS HAVE DEVELOPED ALONG THETA-E GRADIENT THIS MORNING. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ NG nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 1005 AM EDT FRI JUN 27 2008 .SYNOPSIS... HIGH PRESSURE WILL REMAIN OFF THE ATLANTIC COAST THROUGH THE WEEKEND AND ALLOW MOIST UNSETTLED WEATHER TO PERSIST OVER THE CAROLINAS AND NORTHEAST GEORGIA. A COLD FRONT WILL CROSS THE REGION LATE MONDAY AND BRING IN A LITTLE COOLER AND DRIER AIR TUESDAY THROUGH THE END OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... MORNING UPPER AIR SHOWS A LIGHT ZONAL FLOW ACROSS THE REGION. THE SOUNDINGS AT OHX AND FFC HAD WARMER MID LEVEL TEMPERATURES THAN YESTERDAY...ESPECIALLY AT FFC. HOWEVER...MIXED DEWPOINTS WILL BE HIGHER TODAY...AND TAKING A TEMPERATURE OF 89 AND A DEWPOINT OF 65 YIELDS A SBCAPE OF AROUND 1500 AT FFC AND 2000 AT OHX. AT 850 MB...LLVL JET AXIS LOOKS A LITTLE BETTER N OF THE FA...WITH AROUND 30 KTS OF WESTERLY FLOW ACROSS NRN TN/KY AND THE VIRGINIAS. THE RUC IMPLIES WEAK H5 NVA UNTIL LATE AFTERNOON...WHICH IS ALSO WHAT THE HAND ANALYSIS IMPLIES. WITH FREEZING LEVEL TEMPS OVER 13000 FEET...FIRST GUESS 50-55DBZ CORE HEIGHTS OVER AROUND 32KFT LOOK GOOD FOR SEVERE HAIL. WARMER MID LEVEL TEMPS SHOULD RESULT IN LESS ICE IN STORMS THIS AFTERNOON. THIS COUPLED WITH FAIRLY MOIST SOUNDINGS WILL RESULT IN LESS OF A MICROBURST THREAT TODAY...BUT TALLER STORMS COULD STILL PRODUCE 50KT GUSTS. AS FOR CONVECTIVE COVERAGE...THE OVERALL MOISTENING OF THE ENVIRONMENT WILL SUPPORT MORE STORMS THIS AFTERNOON...BUT THE CONTINUED WEAK SHEAR SHOULD STILL RESULT IN NO MORE THAN 40 TO 50 PERCENT COVERAGE IN THE MOUNTAINS...AND 20 TO 30 PERCENT OVER THE PIEDMONT AND FOOTHILLS. THIS LINES UP QUITE WELL WITH WHAT WE HAVE IN THE GRIDS NOW. && .SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/... AS OF 215 AM FRIDAY...THE WEEKEND WILL REMAIN ACTIVE AS FAR AS STRONG TO SEVERE CONVECTION IS CONCERNED. THE MODELS ADVERTISE LOWERING H5 HEIGHTS THROUGH THE PERIOD AND A COLD FROPA BY SUN NIGHT. LOW LEVEL MOISTURE WILL REMAIN HIGH AND DEWPOINTS IN THE UPPER 60S WILL HELP GENERATE HIGH SBCAPES. SATURDAY WILL BE THE LESS DYNAMIC DAY WITH WEAK DEEP FLOW AND NO SIGNIFICANT SHEAR PRESENT...BUT ISO/SCT TS CELLS WILL DEVELOPING THROUGH THE AFTERNOON. ABOVE NORMAL TEMPS SAT WITH GOOD INSOLATION EXPECTED AND ZONAL FLOW ALOFT SLOWLY BECOMING CYCLONIC. INTERESTINGLY THE 00Z GFS IS ONLY PRODUCING AROUND 250 J/KG OF CAPE SUN AFTERNOON AHEAD OF THE FRONT WHEN DEWPOINT POOLING SHOULD BE THE GREATEST. THE 00Z NAM HAS AROUND 2000 J/KG. A CAP IS NOTED ON THE GFS SOUNDINGS SUN AFTERNOON ASSOCIATED WITH A SW/LY H85 35 KT JET...HOWEVER THERE REALLY SHOULD BE NO REASON WHY INSTABILITY WONT BE HIGH...EXCEPT FOR INCREASING CLOUD COVER WITH INCOMING UPPER TROF WHICH MAY HOLD MAX TEMPS INTO THE MID 80S AND ALLOW THE LLVL CAP TO REMAIN IN CONTROL. UPPER DYNAMICS LOOK STRONG SUN WITH STRONG H3 DIVERGENCE SETTING UP THROUGHOUT THE DAY COUPLING WITH INCREASING MID LEVEL CYCLONIC ENERGY WHICH WILL MAXIMIZE DEEP OMEGA. SO...WONT BE SURPRISED TO SEE ORGANIZED STRONG/SEVERE CONVECTION SWEEPING ACROSS THE CWFA DURING THE AFTERNOON. THE COLD FRONT REACHES THE MTNS SUN NIGHT AND SLOWS DOWN ACCORDING TO THE GFS. A STRONG UPPER LEVEL TROF CROSSING THE REGION MON WILL CONTINUE TO KEEP THE ATMOS UNSTABLE AND POTENTIALLY ACTIVE...SO POPS WERE LEFT IN THE LOW CHANCE RANGE MON OUTSIDE THE MTNS WHERE LLVL FLOW WILL CONTINUE TO BE MOIST SW/LY AND MID LEVEL LAPSE RATES WILL BEGIN TO STEEPEN. && .LONG TERM /TUESDAY THROUGH THURSDAY/... AS OF 235 AM FRIDAY...THE LONG RANGE MODELS ARE AGREEING WELL WITH THE OVERALL SYNOPTIC PATTERN DEVELOPING TUE THROUGH THE EXTENDED PERIOD. HOWEVER...THE 00Z GFS IS SLOWER WITH THE FROPA KEEPING THE H5 TROF AXIS TO THE WEST OF THE CWFA THROUGH TUE. THE PREFERRED 12Z ECMWF WILL BE FOLLOWED CLOSELY FOR TIMING GUIDANCE. THE LONG WAVE UPPER TROF CONTINUES TO DEEPEN ACROSS THE EAST COAST AND USHER IN A A NEW AIRMASS WHICH BECOMES MODIFIED FAIRLY QUICKLY...HOWEVER THE CHANGE IN LLVL THETA/E WILL BE NOTICED. THE SENSIBLE WEATHER THROUGH THE EXTENDED WILL FEATURE TEMPS RIGHT AROUND NORMAL AND LOWER DEWPOINTS WITH PERSISTENT W TO NW/LY FLOW. THUNDERSTORMS WILL BE HARD TO COME BY...BUT WITH STRONG UPPER DYNAMICS OVER THE SE REGION DURING THIS TIME OF YEAR...ANY S/LY FLOW FLUCTUATION INCREASING LLVL MOISTURE WILL GREATLY ENHANCE THE POSSIBILITY FOR STORMS AND PRECIP. FOR NOW...THE NEW AIRMASS LOOKS TOO STABLE THROUGH THE PERIOD AND THE CANADIAN HIGH PRESSURE AREA SHOULD BE THE DOMINANT WEATHER FEATURE...SO POPS HAVE BEEN KEPT LESS THAN SLIGHT. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... LIFR CIG RECENTLY DEVELOPED AT KAVL. EARLY VSBL IMAGERY SHOWS A NARROW BAND OF CLOUDS...AND THE STRATUS SHOULD BURN OFF FAIRLY QUICKLY. SPOTTY MVFR VSBYS WILL LINGER ACRS THE FOOTHILLS AND PIEDMONT THRU ABT 13 UTC...WITH AN INCREASE IN CONVECTIVE CLOUD COVER THRU MIDDAY WITH SCATTERED SHOWERS AND TSTMS INTO THE EARLY EVENING. ROUGHLY A PERSISTENCE FCST FOR THE OUTLOOK PERIOD FEATURING JUST DEBRIS CLOUDS TONIGHT ALONG WITH PATCHY MVFR VBSYS EARLY SATURDAY MORNING. OUTLOOK...MOISTURE WILL INCREASE ACROSS THE WESTERN CAROLINAS THROUGH EARLY NEXT WEEK. COVERAGE OF SHRA AND TSRA MAY INCREASE EACH DAY OVER THE WEEKEND...ESPECIALLY OVER THE MOUNTAINS. FOG MAY ALSO DEVELOP WITHIN THE MOUNTAIN VALLEYS DURING THE PRE-DAWN HOURS AND GRADUALLY DIMINISH AFTER SUNRISE. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...SBK NEAR TERM...CSH/MCAVOY SHORT TERM...SBK LONG TERM...SBK AVIATION...CSH/MCAVOY sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 221 PM MDT FRI JUN 27 2008 .SHORT TERM... (TONIGHT AND SATURDAY) ...STRONG-SEVERE THUNDERSTORMS POSSIBLE SERN CO THIS EVENING... ...A LITTLE BETTER CHANCE FOR "WET" THUNDERSTORMS SAT AFTN... CURRENTLY...RELATIVELY STRONG COLD FRONT WAS RACING ACROSS NORTHEAST AND EAST CENTRAL CO EARLY THIS AFTERNOON AND PASSING THE PALMER DIVIDE. THIS WAS A LITTLE AHEAD OF SCHEDULE THAN WHAT THE 12KM NAM-WRF WAS SUGGESTING...HOWEVER...BY MIDAFTERNOON THE FRONT APPEARS TO BE STALLING. SURFACE TEMPERATURES BEHIND THE FRONT WERE IN THE 70S TO LOWER 80S ACROSS NORTHEAST CO...WHILE AHEAD OF THE FRONT TEMPERATURES WERE IN THE 90S TO AROUND 100F ACROSS SOUTHEAST CO. SURFACE DEW POINTS BEHIND THE FRONT WERE IN THE 40S TO LOWER 50S AND A LITTLE LOWER THAN WHAT THE 12KM NAM-WRF HAD BEEN FORECASTING. SURFACE-BASED CAPES AND LIFTED INDICES WERE 400-1800 J/KG AND -2C TO -4C...RESPECTFULLY. LOCAL RADAR FAIRLY QUIET EARLY THIS AFTERNOON. LOW LEVEL CONVERGENCE ALONG THE FRONTAL BOUNDARY IS WEAK AT BEST...SO ANY WEAK CONVECTIVE INHIBITION IS CAPPING THE CONVECTION RELEASE. ALSO...NO PRONOUNCED MIDDLE TO UPPER LEVEL FEATURE TO ENHANCE THE SURFACE-BASED CONVECTION. JUST HAVE SOME SHALLOW CU...SO FAR...FORMING ALONG THE FRONTAL BOUNDARY PER VIS SATELLITE IMAGERY AND LOOKING OUT THE WINDOW. MEANWHILE...ACROSS THE MOUNTAINS AND HIGH VALLEYS...SURFACE DEW POINTS WERE IN THE SINGLE DIGITS TO 20S WITH VERY WARM TEMPERATURES AND LOW DAYTIME HUMIDITY. VISIBLE SATELLITE IMAGERY SHOWING HIGH CLOUD-BASE CU FORMING OVER THE MOUNTAINS/HIGH VALLEYS AND THE MAIN WEATHER IMPACT FOR THESE AREAS THROUGH THIS EVENING WILL BE ISOLATED "DRY" THUNDERSTORMS... "VIRGA-BOMBS"...LOCAL WIND GUSTS UP TO 55 MPH...CLOUD TO GROUND LIGHTNING STRIKES...AND LITTLE OR NO RAINFALL. REST OF THIS AFTERNOON AND TONIGHT...WILL PLAN ON THE COLD FRONT TO CONTINUE MOVING SOUTH AND WESTWARD THROUGH TONIGHT. THE FRONT WILL LIKELY STALL OUT JUST SOUTH OF CO AND PERHAPS MAKE IT PAST THE EASTERN CO MOUNTAINS. THERE IS THE POTENTIAL FOR A LITTLE HIGHER SUSTAINABLE SURFACE DEW POINTS TO MAKE IT ACROSS ALL OF THE MOUNTAINS/HIGH VALLEYS INTO THE WEEKEND...AS THE FLOW SHOOTS THROUGH THE GAPS AND POSSIBLE SELF-MOISTENING OF THE LOW LEVELS GIVEN WHAT LITTLE RAINFALL DOES FALL. NOT SURE WHAT TO DO WITH POPS/WEA GIVEN THE LACK OF DEVELOPMENT...SO WILL LIKELY MAINTAIN THE CURRENT FORECAST FOR CONTINUITY. IF ANY THUNDERSTORMS DO DEVELOP...THE MAIN THREAT WILL BE ALONG THE I-25 CORRIDOR AND SOUTHEAST CO PLAINS THIS EVENING WITH HAIL POSSIBLY UP TO GOLF BALL SIZE...DAMAGING WIND GUSTS...BRIEF MODERATE-HEAVY RAIN...AND CLOUD TO GROUND LIGHTNING. SURFACE-BASED CAPES AND LIFTED INDICES WILL BE 1K-2K J/KG AND -2C TO -6C...RESPECTFULLY BEHIND THE FRONT THIS EVENING. A COUPLE OF SHORTWAVES MAY HELP ENHANCE CONVECTION...BUT HARD PRESSED TO FIND ANYTHING IN THE RUC AND SATELLITE. THERE ARE A COUPLE IN NM...BUT THOSE MAY NOT MAKE IT INTO SOUTHERN CO. TOUGH CALL ON THE SUSTAINABLE OVERNIGHT MOIST CONVECTION POTENTIAL TONIGHT. 0-6KM MOST UNSTABLE(MUCAPES) ARE PROGGED TO 1.5-2.5K J/KG BEHIND THE FRONT... BUT THERE APPEARS TO BE NO TRIGGER TO KEEP THE MOIST CONVECTION GOING...EXCEPT ANY ROGUE OUTFLOW BOUNDARIES COLLIDING TOGETHER OR AGAINST THE MOUNTAINS. THERE IS SOME WEAK 800-700MB WARM AIR ADVECTION JUST NORTH OF THE CO/NM BORDER...WHICH COULD KEEP A FEW SHOWERS AND THUNDERSTORMS GOING OVERNIGHT...SO WILL MAINTAIN SOME VERY LOW POPS IN THOSE AREAS OVERNIGHT. SATURDAY...THIS COULD BE ANOTHER HIGH IMPACT WEATHER DAY. MODELS INSIST ON MOISTENING UP THE SURFACE AND LOW LEVELS THROUGH TIME. MIDDLE TO UPPER LEVEL RIDGE WILL BE PARKED ACROSS WESTERN CO INTO THE DESERT SOUTHWEST. AMPLE MOISTURE AND INSTABILITY SHOULD BE IN PLACE ACROSS MUCH OF CENTRAL...SOUTH CENTRAL...AND ALONG THE I-25 CORRIDOR SATURDAY AFTERNOON. THERE COULD BE SOME MODERATE TO HEAVY RAIN POTENTIAL GIVEN H7-H5 SPECIFIC HUMIDITY VALUES AROUND 6 G/KG...STEERING CURRENTS OF 10KTS OR LESS...AND WET BULB ZERO HEIGHTS OF 13K-15K FT MSL ALONG I-25 CORRIDOR AND THE MOUNTAINS/HIGH VALLEYS. THE MAIN THUNDERSTORM POTENTIAL WOULD BE HAIL AROUND UP TO 3/4 INCH AND WIND GUSTS UP TO 60 MPH NEAR THE STRONGER UPDRAFTS. OVERALL...HIGH TEMPERATURES WILL BE MUCH COOLER THAN THE PAST COUPLE OF DAYS. METZE .LONG TERM... (SATURDAY NIGHT THROUGH FRIDAY) CHALLENGES ARE PRECIPITATION COVERAGE AND DURATION EARLY ON. SATURDAY NIGHT THROUGH SUNDAY NIGHT...UPPER HIGH OVER UTAH...WITH FAIRLY DEEP EASTERLY FLOW ACROSS GOOD CHUNK OF OUR CWA. CONVECTION ONGOING FROM THE AFTERNOON WILL LAST THROUGH THE EVENING...AND PERHAPS PAST 06Z SUNDAY IN THE PLAINS AND EASTERN MOUNTAINS. CAPE VALUES GENERALLY BELOW 1000 J/KG...AND SPC NOT OUTLOOKING OUR CWA FOR SEVERE STORMS. ANOTHER ROUND OF STORMS WILL DEVELOP SUNDAY AFTERNOON AND LAST THROUGH THE EVENING. 12Z NAM12 HAS HEAVIER RAIN OVER THE MOUNTAINS...BUT THAT REMAINS TO BE SEEN. MAIN THREAT FROM STORMS BOTH DAYS WILL BE LIGHTNING...GUSTY WINDS...AND BRIEF HEAVY RAIN. WITH LOWER TEMPERATURES IN MID LEVELS WOULD EXPECT HIGHS TO STAY IN THE 80S ACROSS THE PLAINS...WITH MAINLY 60S AND 70S MOUNTAINS AND HIGH VALLEYS. MONDAY THROUGH 4TH OF JULY...MODELS FAVOR SEMI-PERMANENT RIDGE TO BE OVERHEAD...WITH SOME TRAPPED MOISTURE. THE UPSHOT WILL BE DAILY ROUNDS OF ISOLATED TO SCATTERED STORMS. WITH MID LEVEL TEMPERATURE EXPECTED TO RISE SOME 2 TO 4 DEGREES CELSIUS FROM WEEKEND VALUES...HIGH TEMPERATURES WILL BE IN THE MID 80S TO MID 90S PLAINS...70S AND 80S HIGH VALLEYS...AND 60 AND 70S MOUNTAINS. -TLM- && .AVIATION... PER THE SHORT TERM DISCUSSION...SIGNIFICANT COLD FRONT WILL CONTINUE MOVING ACROSS SOUTHEAST CO...AND THROUGH KCOS AND KPUB THIS AFTERNOON. ISOLATED-SCATTERED SHOWERS AND THUNDERSTORMS WILL PRIMARILY AFFECT THE KCOS AND KPUB TERMINAL FORECAST POINTS THROUGH 06Z/28 WITH THE POTENTIAL FOR LARGE HAIL...DAMAGING WIND GUSTS...AND CLOUD TO GROUND LIGHTNING. ISOLATED-SCATTERED SHOWERS/THUNDERSTORMS WILL AGAIN BE POSSIBLE FOR KCOS...KPUB...AND KALS SATURDAY AFTERNOON WITH THE POTENTIAL FOR LARGE HAIL...MODERATE-HEAVY RAIN...DAMAGING WIND GUSTS AND CLOUD TO GROUND LIGHTNING. METZE && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 17/13 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL 102 PM EDT FRI JUN 27 2008 .SYNOPSIS...AN UPPER LOW IS SPINNING OVER THE WESTERN GULF WITH A 59S RIDGE CENTERED ACROSS SOUTH FL. MSAS/RUC LOCATES SURFACE RIDGE AXIS FROM ATLANTIC TO THE GULF...CROSSING CENTRAL FL NEAR TAMPA BAY. TBW 88D HAS A FEW SHOWERS WELL OFFSHORE AND IN NORTH LEVY ATTM. SOME HIGH CLOUDINESS...BUT SLIGHTLY LESS THAN YESTERDAY...COVERS MUCH OF THE CWA. && .SHORT TERM (TONIGHT - SUNDAY)...THE 500 HPA RIDGE OVER SOUTH FL BUILDS IN SAT BUT THEN BEGINS TO SHIFT EAST SUN AS LARGE SCALE TROUGHINESS MOVES IN OVER THE EASTERN U.S. THE SOUTH FL RIDGE NUDGES THE U/L LOW OVER THE WESTERN GULF WEST WARD SAT. THIS MAY TRIM SOME OF THE HIGH CLOUDINESS OF THE PAST COUPLE OF DAYS DOWN BUT THE ATMOSPHERE WILL REMAIN MOIST. THE SURFACE RIDGE AXIS RESIDES ACROSS FL IN THE VICINITY OF TAMPA BAY THROUGH THE PERIOD. THE PATTERN OF WET AFTERNOONS TO CONTINUE THROUGH THE WEEKEND. A MOIST UNSTABLE ATMOSPHERE...SOME DAYTIME HEATING...WEAK LOW LEVEL FLOW WILL ALL PROVIDE STORMS IN THE SCATTERED TO NUMEROUS RANGE. WITH RIDGE AXIS PRETTY MUCH BISECTING THE CWA WITH SE WINDS FROM TAMPA BAY SOUTH AND SW WINDS TO THE NORTH WILL KEEP THE HIGHER POPS ACROSS THE SOUTH. TEMPS ALOFT GRADUALLY WARM BUT STILL COOL AND WITH THE EARLIER MENTIONED PARAMETERS WOULD EXPECT SOME STORMS TO BE STRONG TO POSSIBLY SEVERE WITH HAIL AND WINDS BEING THE MAIN THREATS. HIGHS WILL RUN NEAR NORMAL WITH THE LOWS JUST ABOVE NORMAL. MAV GUIDANCE CONTINUES TO RUN TOO LOW WITH POPS AND HAVE LEANED TOWARD THE HIGHER MET. .LONG TERM (SUNDAY NIGHT - FRIDAY)...IN THE MID/UPPER LEVELS...LOW OVER GREAT LAKES REGION WILL DIG SOUTH THEN WILL SHIFT INTO CANADA BY MIDWEEK. WEAK RIDGING WILL BUILD BACK OVER FLORIDA BY THE END OF THE WEEK AS THE TROUGH MOVES OUT. IN THE LOWER LEVELS...WEAK FRONT OVER THE SOUTHEAST WILL SLOWLY DRIFT TO THE SOUTH AND STALL OVER NORTH FLORIDA EARLY NEXT WEEK. SURFACE RIDGE AXIS ACROSS CENTRAL FLORIDA ON TUESDAY WILL MOVE NORTHWARD TOWARDS THE END OF THE WEEK. SURFACE WINDS WILL BE SOUTHEASTERLY FOR THE BEGINNING OF THE WEEK AND EAST/SOUTHEAST FOR THE REST OF THE PERIOD...LEADING TO TYPICAL SUMMERTIME AFTERNOON SHOWERS AND THUNDERSTORMS ALONG SEABREEZE AND BOUNDARY INTERACTIONS. TEMPERATURES WILL BE NEAR CLIMO...WITH HIGHS IN THE UPPER 80S ALONG THE COAST TO THE LOWER 90S INLAND...AND LOWS IN THE MID 70S. && .AVIATION...ANOTHER AFTERNOON OF SCT +TSRA EXPECTED INTO THIS EVENING ACROSS THE AREA PRODUCING MVFR/LOCAL IFR CONDITIONS CIGS/VSBY AND GUSTY WINDS AT TAF SITES. COULD ALSO SEE SOME AREAS OF MVFR VISIBILITIES IN FOG IN THE MORNING...OTHERWISE VFR CONDITIONS ARE EXPECTED. && .MARINE...WINDS 10KT OR LESS THROUGH THE PERIOD. A SURFACE RIDGE AXIS BISECTING THE CENTRAL COASTAL WATER INTO AT LEAST THE MIDDLE OF NEXT WEEK WILL KEEP SW WINDS IN THE SOUTH AND SW IN THE NORTH. MAIN HAZARDS WILL BE STRONG GUSTY WINDS WITH HIGHER SEAS AND LIGHTNING IN SCATTERED THUNDERSTORMS THAT PUSH OFFSHORE THE WEST COAST OF FLORIDA DURING THE AFTERNOONS AND BECOME ISOLATED DURING THE EVENINGS. && .FIRE WEATHER...NO CONCERNS THROUGH THE WEEKEND INTO EARLY NEXT WEEK.. && .PRELIMINARY POINT TEMPS/POPS... TPA 77 91 77 92 / 20 60 20 60 FMY 74 92 74 92 / 20 60 20 60 GIF 73 92 74 93 / 20 60 20 60 SRQ 74 90 74 90 / 20 50 20 50 BKV 72 90 71 91 / 20 50 20 50 SPG 80 90 80 90 / 20 50 20 50 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...NONE. GULF WATERS...NONE. && $$ SHORT TERM/MARINE...RKR LONG TERM/AVIATION...CNC/RD fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 326 PM CDT FRI JUN 27 2008 .DISCUSSION... FORECAST FOCUS IS ON CONVECTIVE THREAT IN THE NEAR TERM. SEVERAL FEATURES OF INTEREST EVIDENT ON AFTERNOON WEATHER MAP. FIRST...MOISTURE HAS RETURNED TO MUCH OF CENTRAL KANSAS...WITH A POOL OF 65F TO 75F DEGREE DEWPOINTS FROM CENTRAL OK THROUGH NE KS. A SFC TROUGH WAS ANALYZED FROM NEAR DDC TO NEAR OMA...WITH THE SYNOPTIC COLD FRONT JUST BEHIND...FROM EAST CENTRAL TO SOUTH CENTRAL NE. FINE LINE EVIDENT ON KUEX WSR-88D. WEAK CONVERGENCE WAS NOTED ALONG THE TROUGH AXIS. ALOFT...STRONG 500MB SHORTWAVE CONTINUES TO DIG INTO SOUTHERN SASKATCHEWAN THIS AFTERNOON...WITH LEADING LOBE OF ENERGY OVER EASTERN NE...AND NEXT LOBE DIVING INTO NORTHERN MONTANA. SEVERE THREAT LATER TODAY HINGES UPON CONVERGENCE ASSOCIATED WITH THE TROUGH OR THE FROPA FOR INITIATION...ENHANCED BY THE LOBE OF ENERGY ASSOCIATED WITH THE 500MB SHORTWAVE. MODELS HAD HINTED AT AN OUTFLOW BOUNDARY KICKED OUT BY MORNING CONVECTION TO LIFT BACK NORTHWARD TODAY...BUT THIS HAS NOT BEEN REALIZED PER CURRENT ANALYSIS. 18Z SPECIAL SOUNDING DEPICTS CAP STILL PRESENT OVER TOP...BUT CAPE CONTINUES TO BUILD AS MOISTURE ADVECTS INTO THE LOW LEVEL ATMOSPHERE. 19Z RUC DEPICTS AROUND CAPE VALUES AROUND 3000J/KG ALONG AXIS OF BEST MOISTURE. LL WINDS LOOK SOMEWHAT UNREPRESENTATIVE AS COMPARED TO SITES ACROSS THE CWA--AS MORNING CONVECTION RENDERED THE NEAR TOP WIND FIELD SOMEWHAT ANOMALOUS. SPEED SHEAR LOOKS A BIT BETTER THAN YESTERDAY...AND DIRECTIONAL SHEAR APPEARS MORE FAVORABLE OUT WEST. PRIMARY SEVERE WEATHER THREAT LOOKS TO BE LARGE HAIL IN THE NEAR TERM...TRANSITIONING TO A WIND EVENT TONIGHT...WHEN DISCRETE CELLS...POTENTIALLY SUPERCELLS...CONGEAL INTO A COMPLEX AND DIVE SOUTHEASTWARD. TOMORROW...SHOWERS/ISOLATED THUNDER MAY LINGER SATURDAY MORNING...BUT EXPECT MOST PRECIP TO CLEAR THE CWA BY LATE MORNING. A PLEASANT START TO THE WEEKEND IS IN STORE...WITH NORTHWESTERLY WINDS...COOLER TEMPERATURES AND LESS HUMID CONDITIONS. EK SHORTWAVE TROUGH MOVING AROUND THE UPPER LOW OVER THE GREAT LAKES ACROSS IOWA AND MISSOURI SATURDAY NIGHT WILL KEEP SOME CLOUDS NEAR THE NORTHEAST CORNER OF THE CWA. UPPER FLOW WILL BE NORTH TO NORTHWEST WITH COOL ADVECTION AND LOWER DEW POINTS THROUGH SUNDAY. HIGH PRESSURE WILL BUILD INTO CENTRAL AND EASTERN KANSAS AND REMAIN THROUGH MONDAY NIGHT. BE TUESDAY AND TUESDAY NIGHT RETURN FLOW COMMENCES ACROSS THE CENTRAL PLAINS WITH A WARM FRONT MOVING NORTHEAST TUESDAY NIGHT INTO WEDNESDAY MORNING. HAVE MAINTAINED SMALL CHANCES FOR ELEVATED THUNDERSTORMS THROUGH WEDNESDAY MORNING. TEMPERATURES WILL BE COOLER SUNDAY AND MONDAY WITH LOWER HUMIDITY AND HAVE ADJUSTED HIGHS A LITTLE DOWNWARD ON SUNDAY AND MONDAY GENERALLY IN THE LOW TO MID 80S. LOWS IN THE 50S SUNDAY AND MONDAY MORNINGS. FOR THE END OF THE WEEK MODELS ARE STILL ADVERTISING A LOWERING OF HEIGHTS ACROSS THE ROCKIES AND A NORTHWEST FLOW ACROSS THE CENTRAL PLAINS. A FRONTAL BOUNDARY IS STILL FORECAST TO BE LINGERING ACROSS THE REGION THURSDAY POSSIBLY INTO INDEPENDENCE DAY. MODEL DIFFERENCES ENOUGH TO KEEP JUST SMALL PROBABILITIES. WITH NORTHWEST FLOW AND PERTURBATIONS MOVING THROUGH THE FLOW ACROSS THE CENTRAL PLAINS WOULD NOT BE SURPRISED TO SEE SOME MCS`S DEVELOPING DURING THE NIGHTTIME HOURS. TEMPERATURES WARM BACK INTO THE UPPER 80S FOR THE END OF THE WEEK. 53 && .AVIATION... VFR CONDITIONS EXPECTED THROUGH THE AFTERNOON...WITH INCREASING SOUTHERLY WINDS. SEVERAL WEAK MESOSCALE BOUNDARIES LINGER OVER NORTHEAST KANSAS...MAKING FOR A CHALLENGING WIND FORECAST. IN ADDITION...SOMEWHAT STATIONARY BOUNDARY STRETCHING THROUGH CENTRAL KANSAS AND UPSTREAM COLD FRONT WILL EXACERBATE WIND CHALLENGES. EXPECT TO SEE GRADUAL SWING TO THE SOUTHWEST...BECOMING NORTHERLY BEHIND THE COLD FRONT AFTER 06Z-07Z. VFR CONDITIONS TO PERSIST THROUGH THE PERIOD...SAVE FOR THE 23Z-07Z TIME FRAME. MAINTAINED VCTS DURING THIS TIME...AND INTRODUCED TSRA FROM WEST//MHK// TO EAST//TOP AND FOE// WITH FROPA BETWEEN 23Z AND 02Z WITH VRB WIND GUSTS TO 30MPH AND MVFR CIGS AND VIS. EK && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 145 PM EDT FRI JUN 27 2008 .SHORT TERM.../THE REST OF TODAY/ VERY LITTLE ADJUSTMENT IN FORECAST IS NECESSARY. RUC HAS A NICE HANDLE ON SHORTWAVES THOUGH IT APPEARS OVERDONE FOR CAPE IN SOUNDINGS. CURRENT CONVECTION OVER EXTREME SOUTHEAST KY DEVELOPED IN AN AREA OF 2000 J/KG FROM 925-850 MB LAYER (IN RUC...IN NAM THAT AREA IS SOUTH OF KY) AND AIDED BY THKJKLNOWJKLE TAIL END OF A VORT. A WEAKER WAVE IS MOVING INTO CENTRAL KY. STRONGER SHORTWAVES OVER MO/IL MIGHT AFFECT AREA TONIGHT. IN ADDITION THE RUC SHOWS SOME DECENT 250 MB DIVERGENCE TO AID CONVECTION ABOUT 21Z THIS AFTERNOON THEN EXPECT ITS CONVERGENT COUPLET TO HELP END IT BY 28/00Z. ATTM...THINK SCATTERED STORMS ARE A GIVEN THIS AFTERNOON AND A FEW OF THEM GETTING SEVERE ARE LIKELY. DON/T THINK THE CLOUDS ARE GOING TO KEEP TEMPERATURES DOWN MUCH FROM YESTERDAYS LEVELS. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /TODAY THROUGH SUNDAY NIGHT/ 06Z SFC ANALYSIS SHOWS WANING HIGH PRESSURE OVER THE SOUTHEAST PORTION OF THE NATION WHILE A WAVY WARM FRONT IS LAYING ACROSS THE SOUTHERN GREAT LAKES RUNNING EAST FROM A LOW PRESSURE CENTER OVER THE UPPER MIDWEST. EACH DAY THE UPPER RIDGE HAS BROKEN DOWN A BIT MORE SO THAT A BAND OF SHOWERS AND THUNDERSTORMS WERE ABLE TO PUSH INTO THE WESTERN PORTION OF THE CWA THIS PAST EVENING. WHILE THESE INITIAL STORMS HAVE STALLED AND DISSIPATED...THEY LEFT BEHIND A BOUNDARY THAT CONTINUES TO SHOW SIGNS OF ACTIVITY...JUST TO THE NORTHWEST OF JKL. A LARGE FACTOR IN THE ABILITY OF THESE STORMS TO SETTLE DEEPER INTO OUR REGION THAN PREVIOUS DAYS IS THE PRESENCE OF A WELL DEFINED MCV CURRENTLY CUTTING ACROSS CENTRAL OHIO. THE SKY COVER MIRRORS THE RADAR IMAGES WITH LOWER AND THICKER CLOUDS OVER THE WESTERN PORTION OF THE STATE AND MAINLY RESIDUAL MID LEVEL CLOUDS FOUND OVER THE EAST. TEMPERATURES OVER THE AREA ARE RUNNING FROM THE MID 60S IN THE VALLEYS TO THE LOWER 70S ON THE RIDGES WHILE DEWPOINTS ARE UP IN THE MIDDLE 60S THROUGH MOST OF THE AREA. THE MODELS ARE IN FAIRLY GOOD AGREEMENT ALOFT WITH AN UNSEASONABLY STRONG...CLOSED UPPER LOW RIDING EAST SOUTHEAST THROUGH THE UPPER MIDWEST AND INTO THE NORTHERN OHIO VALLEY ON SATURDAY. THIS HIGHLY AMPLIFIED FEATURE THEN SPINS INTO A DEEP LOW OVER THE GREAT LAKES FOR SUNDAY...MAINTAINING IMPRESSIVE TROUGHING OVER THE OHIO VALLEY RIGHT INTO THE BEGINNING OF THE NEW WORK WEEK. THE MODELS MATCH UP QUITE WELL THROUGH SATURDAY BEFORE THE 12Z ECMWF AND 00Z GFS PULL THE LOW NORTHEAST A TAD QUICKER THAN THE LATEST NAM. NEVERTHELESS... PREFER THE NAM/S ATTEMPT AT FORECASTING THE VARIOUS SHORTWAVES... SYNOPTIC AND CONVECTIVELY INDUCED...RESPONSIBLE FOR THIS PATTERN EVOLUTION. IN GENERAL...THE SPECIFICS OF THE NAM12 WERE FOLLOWED THROUGH 84 HOURS. SENSIBLE WEATHER FOR EASTERN KENTUCKY WILL BE DRIVEN BY THE BUILDUP OF INSTABILITY AND MOISTURE THROUGH THE LOWER OHIO VALLEY IN A BROAD PRE-FRONTAL WARM SECTOR TODAY AND INTO SATURDAY. THE UNDERLYING CONDITIONS FOR CONVECTION...WHILE HEAVILY INFLUENCED BY THE DIURNAL CYCLE OF INSTABILITY...WILL BE FURTHER ENHANCED BY THE PRESENCE OF SFC BOUNDARIES AND PROPAGATING DOWNSTREAM MCVS. ACCORDINGLY...HAVE ATTEMPTED TO DRAW THE POP...AND IN A SIMILAR MANNER SKY...GRIDS BASED ON AN EXTRAPOLATION OF CURRENT ACTIVITY...LATEST SHORT RANGE GUIDANCE FROM THE NAM12 AND A STRONG DIURNAL COMPONENT. THIS MUDDLED FORECAST SITUATION FOR TODAY AND TONIGHT BECOMES MORE CLEAR ON SATURDAY WHEN A WELL MODELED COLD FRONT WILL BE ENTERING INTO AND CROSSING THE AREA LATER IN THE DAY. THIS FRONT WILL ALSO HAVE THE UPPER SUPPORT OF A STRENGTHENING MID LEVEL WIND FIELD IN ACCORDANCE WITH THE CLOSE APPROACH OF THE UPPER LOW. IN CONJUNCTION WITH AN ALREADY QUITE MOIST AIR COLUMN OVER THE REGION...THE UPPER DYNAMICS WILL YIELD THE BEST SHOT FOR ORGANIZED AND POTENTIALLY SEVERE CONVECTION WITH THE MAIN THREATS BEING DAMAGING WIND GUSTS AND ISOLATED LARGE HAIL. IN ADDITION...THE STORMS OF THE SHORT TERM PERIOD SHOULD BE EFFICIENT PRECIPITATION PRODUCERS RAISING THE POTENTIAL FOR LOCALIZED EXCESSIVE RAINFALL...HOWEVER THE ANTECEDENT CONDITIONS WILL MAKE THIS LESS OF A CONCERN THAN NORMAL...ALTHOUGH WHAT IS NORMAL IN THE GOING ON TWO YEARS OF DROUGHT OR NEAR DROUGHT ACROSS THE AREA. INTERPRETING THE PREFERRED NAM SOLUTION FOR SFC FEATURES AND RESULTING WX...WILL BRING THE COLD FRONT EAST THROUGH THE CWA SATURDAY NIGHT AND SLOWLY CLEAR THE POPS OUT WEST TO EAST ON SUNDAY...THOUGH HELD THEM RELATIVELY STEADY FOR A TIME AT PEAK HEATING AND DURING A TIME OF INCREASING MID LEVEL LAPSE RATES SUNDAY AFTERNOON. OUR PROXIMITY TO THE UPPER LOW CENTER SUNDAY NIGHT WILL KEEP THE THREAT OF CONVECTION CONTINUING INTO MONDAY MORNING... ESPECIALLY ACROSS OUR NORTHERN COUNTIES. DESPITE PREFERRING THE MET/S PARENT MODEL...ACTUALLY SAW THE MAV TEMPERATURE NUMBERS AS MORE REASONABLE THROUGH THE WEEKEND. AS FOR POPS DID END UP CLOSEST TO THE MET ONES. .LONG TERM.../MONDAY THROUGH THURSDAY/ ENSEMBLES AND OPERATIONAL RUNS SREF/GFS/ECMWF/CANADIAN/NOGAPS AGREE FAIRLY WELL REGARDING THE UNUSUALLY HIGH AMPLITUDE (FOR JULY) AND POSITION OF SHORTWAVE TROUGH SWEEPING THROUGH EASTERN U.S. LATE THIS WEEKEND AND THEN BUILDING THE RIDGE AGAIN. HPC GUIDANCE WAS CONSISTENT WITH THIS IDEA AND HELD ON TO IT. MODELS HAVE BEEN SLOWING PROGRESSION OF THAT SHORTWAVE DOWN AND WE MAY BE HOLDING ONTO AND/OR EXTENDING RAIN CHANCES SUN/MON (MEX SHOWS CATEGORICAL POPS ON SUN). BY WED THE PATTERN LOOKS SIMILAR TO CURRENT CONDITIONS AND A RETURN TO HOT/HUMID IS LIKELY BY THEN. && .AVIATION.../18Z TO 18Z/...UPDATED ISOLATED TO SCATTERED THUNDERSTORMS WILL PASS NEAR TAF SITES NEXT SEVERAL HOURS RESULTING FROM A SLOWLY MOVING SHORTWAVE. THESE STORMS ARE TO BE MOVING FASTER THAN THE SHORTWAVE AND WILL EXPECT NEW DEVELOPMENT BEHIND THE CURRENT ONES FOR A FEW HOURS. THINK THEY WILL BECOME FEWER IN NUMBER TOWARDS LATE AFTERNOON. ISOLATED SMALL HAIL AND STRONG GUSTS WILL ACCOMPANY THE STORMS AND WILL UPDATE IF THEY APPEAR LIKELY TO MORE DIRECTLY AFFECT AN AIRPORT. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...GREIF/GV LONG TERM....GV AVIATION...GV ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 430 PM EDT FRI JUN 27 2008 .SYNOPSIS... 20Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED UPPER RIDGING ALONG THE WEST COAST AND OVER THE EASTERN 1/3 OF THE U.S....AND TROUGHING DIGGING DOWN FROM SOUTH CENTRAL CANADA INTO THE NORTHERN PLAINS. WITHIN THIS TROUGH...FEATURES TO NOTE ARE A SHRTWV FROM DLH INTO SW WI...A STRONGER SHRTWV OVER THE EASTERN DAKOTAS AND AN UPPER LOW IN SOUTHERN SASKATCHEWAN. BOTH SHRTWVS ARE PRODUCING SCATTERED SHOWERS AND THUNDERSTORMS...WITH THE EASTERN DAKOTAS ONE GETTING A LITTLE MORE BOOST FROM MORE DAYTIME HEATING THAT OCCURRED IN MN...COMPARED TO WI AND UPPER MI WHICH HAD SOME HIGH CLOUD TO DEAL WITH. A SVR TSTM WATCH IS IN EFFECT FOR MUCH OF MN DOWNSTREAM OF THE EASTERN DAKOTAS SHRTWV. IN THE WAKE OF THE SECOND SHRTWV BUT AHEAD OF THE UPPER LOW...QUITE A BIT OF DRYING IS OCCURING IN NORTH DAKOTA...NOTED BY DEWPOINTS DROPPING INTO THE 30S AND 40S. ON THE NORTH SIDE OF THE UPPER LOW...A DEFORMATION ZONE CAN BE SEEN IN SATELLITE IMAGERY ACROSS CENTRAL SASKATCHEWAN. OTHER ITEM TO NOTE IS FOG ON LAKE SUPERIOR...THOUGH IT IS GETTING HARD TO SEE WITH INCREASING CLOUD COVER. SHIPS ARE STILL REPORTING IT...AND A FEW EARLIER TODAY HAD DENSE FOG. && .SHORT TERM (TONIGHT AND SATURDAY)... FIRST SHRTWV MOVING NE OUT OF WI WILL CROSS UPPER MI LATE THIS AFTN AND EARLY THIS EVENING. AHEAD OF THE SHRTWV...SHOWERS WITH A FEW EMBEDDED THUNDERSTORMS ARE EXPECTED AS DPVA HELPS WEAKEN THE CAP OVER THE CWA. IN FACT...MODIFYING THE 1740Z TAMDAR SOUNDING FROM SAW FOR THE OBSERVATION AT IMT YIELDED 600 J/KG OF CAPE WITH NO CIN FROM THE SURFACE TO 470 MB. A BREAK IN THE PCPN MAY OCCUR AFTER THIS SHRTWV AND THE NEXT SHRTWV OVER THE FAR EASTERN DAKOTAS...THOUGH THIS HAS NOT BEEN DEPICTED IN THE GRIDS. SHOWERS AND THUNDERSTORMS DEVELOPING OVER MN AHEAD OF THE EASTERN DAKOTAS SHRTWV MAY CONGEAL INTO AN MCS...AND THEN GET FORCED EAST OR NORTHEASTWARD ACROSS UPPER MI AS THE UPPER LOW IN SE SASKATCHEWAN DIGS INTO NORTH DAKOTA. RAISED POPS TO 80 AS THERE IS DECENT MODEL AGREEMENT AMONGST THE NAM...GFS AND UKMET. SVR WX POTENTIAL IS MARGINAL WITH 0-6KM BULK SHEAR AT 25-30KT...BUT WITH A STRONG SHRTWV MOVING IN...WOULD NOT BE SURPRISED TO SEE ONE OR TWO STORMS TRY TO GO SEVERE. EVEN WITH CURRENT ACTIVITY IN THE WESTERN U.P....ONE STORM ALMOST BECAME SEVERE. LOOKS LIKE PCPN WILL END SW TO NE OVERNIGHT AS THE DRY SLOT WORKING IN ACROSS THE DAKOTAS MOVES OVERHEAD. THIS DRYING ALOFT COMBINED WITH LINGERING LOW LEVEL MOISTURE MAY RESULT IN SOME FOG DEVELOPMENT OVERNIGHT...AND HAVE INCLUDED PATCHY FOG AS A RESULT. ADJUSTED LOW TEMPS UPWARD A LITTLE GIVEN CLOUD COVER AND HIGH DEWPOINTS. UPPER LOW MOVES INTO UPPER MI ON SATURDAY. ALTHOUGH COLD MID-LEVEL TEMPS ARE ASSOCIATED WITH THE UPPER LOW (500MB READINGS AROUND -16 TO -17C)...AM VERY CONCERNED WITH FORECAST SOUNDINGS WHICH SHOW A DECENT AMOUNT OF DRY AIR ACCCOMPANYING THE COLD TEMPS. THIS IS ESPECIALLY TRUE OVER THE WESTERN HALF OF THE U.P. WHERE IF MIXING UP TO 850MB OCCURS...DEWPOINTS DROP OFF INTO THE UPPER 40S (ANY HIGHER MIXING HEIGHTS RESULTS IN EVEN LOWER DEWPOINTS). THEREFORE ADJUSTED THE POPS DOWN TO 40 FOR THIS AREA. IN THE EASTERN U.P....IT APPEARS THE MOISTURE WILL NOT BE AS QUICK TO ERODE WITH DEWPOINTS LIKELY STAYING UP AROUND 60F. THE COMBINATION OF DAYTIME HEATING...COOLING ALOFT FROM THE UPPER LOW WILL PRODUCE CAPE VALUES PERHAPS UP NEAR 1000J/KG. FORCING APPEARS TO BE A SECONDARY TROUGH MOVING INTO ALGER/DELTA COUNTIES IN THE AFTERNOON AND A LAKE BREEZE COMING OFF LAKE SUPERIOR. AS A RESULT...HAVE WENT WITH LIKELY POPS IN THE AFTERNOON FOR THE EASTERN U.P.. THE UPPER LOW MAY DROP FAR ENOUGH SOUTH BY LATE IN THE AFTERNOON TO HAVE SOME DEFORMATION PCPN TO CROSS WESTERN LAKE SUPERIOR AND INTO THE FAR WESTERN U.P....AND THEREFORE HAVE POPS OF 50-60 IN THIS AREA. GOING FORECAST HIGH TEMPS LOOK REASONABLE GIVEN 850MB TEMPS OF 10-11C. .LONG TERM (SAT NIGHT THROUGH NEXT FRI)... MAIN CONCERNS FOR SUNDAY ARE RAIN CHANCES AND TEMPERATURES. THE NAM AND GFS DIFFER WITH REGARDS TO THE UPPER LOW TRACK SATURDAY NIGHT INTO SUNDAY...WHICH PLAYS AN IMPORTANT ROLE IN DETERMINING POPS SAT NIGHT AND SUNDAY. THE NAM IS MUCH FURTHER SOUTH OVER WISCONSIN WHILE THE GFS TAKES THE UPPER LOW OVER LAKE SUPERIOR. AT THIS TIME...IT LOOKS LIKE THE NAM SOLN MAY BE THE WAY TO GO FOR NOW GIVEN THE GFS GRID SCALE CONVECTIVE FEEDBACK ISSUES OVER LAKE SUPERIOR LATE TONIGHT INTO SATURDAY MORNING. THIS CAUSES THE GFS TO KEY ON THE NEWLY DEVELOPED WAVE RATHER THAN KEEPING THE BEST ENERGY WITH THE INITIAL WAVE CURRENTLY OVER SRN SASKATCHEWAN. AS THE SHORT TERM FORECASTER DISCUSSED...MUCH OF UPPER MICHIGAN WILL BE UNDER RELATIVELY DRY AIR SAT AFTN AND EVENING BEHIND THE LOW AS IT MOVES THROUGH SAT AFTN. MAY BE SOME LINGERING DIURNAL SHOWERS EARLY... HOWEVER...AS THE LOW MOVES E-NE SAT NIGHT...WRAP AROUND MOISTURE WILL MOVE INTO THE AREA FROM THE WEST OVERNIGHT ALLOWING FOR ADNL SHOWERS TO DEVELOP. THERE WILL LIKELY BE A BAND OF SHOWERS MOVING THRU THE REGION LATE SAT NIGHT INTO SUNDAY MORNING BEFORE DRYING AND SUBSIDENCE DEVELOPS FROM WEST TO EAST AS THE LOW MOVE INTO QUEBEC. THE BEST CHANCE FOR SHOWERS WILL LIKELY BE ACROSS THE NORTHERN U.P. INTO LAKE SUPERIOR WHERE THE BEST ISENTROPIC LIFT AND BETTER MOISTURE WILL OCCUR. WILL GO WITH HIGH CHC POPS FOR THE ENTIRE NIGHT ACROSS WESTERN UPPER MICHIGAN AND LATE ACROSS CENTRAL AND EASTERN UPPER MICHIGAN. DRYING MOVES IN RAPIDLY ON SUNDAY...ALONG WITH SUBSIDENCE AND A BRISK N-NE WINDS. TEMPS WILL STRUGGLE ON SATURDAY WITH THIS NORTH WIND AND MOST PLACES WILL NOT RISE OUT OF THE 60S ON SUNDAY. IN FACT...MANY PLACES NEAR LAKE SUPERIOR WILL NOT SEE TEMPS OUT OF THE 50S. DESPITE THE COLD AIR ALOFT...DIURNAL INSTABILITY SHOULD BE AT A MINIMUM GIVEN COOL BOUNDARY LAYER. MAY SEE A FEW AFTN STORMS...BUT THEY WILL LIKELY BE CONFINED TO THE EASTERN HALF OF UPPER MICHIGAN. WILL THEREFORE TAPER POPS FROM 30 ACROSS THE WEST TO 50 ACROSS THE EAST. THE NAM ALSO SUGGESTS THAT ANOTHER WAVE WILL ROTATE INTO EASTERN UPPER MICHIGAN SUNDAY AFTERNOON POSSIBLY HELPING TO ENHANCE ANY PCPN. WILL GO DRY SUNDAY NIGHT INTO MONDAY...HOWEVER TEMPS WILL CONTINUE TO BE COOL WITH N-NW BOUNDARY WINDS AND RELATIVELY COOL TEMPS ALOFT. SHOULD BE PARTLY TO MOSTLY SUNNY...SO TEMPS WILL MODERATE SOME FROM SUNDAY WITH TEMPS IN THE MID-UPPER 60S...BUT CONTINUED COOLER NEAR THE LAKE. THE MEDIUM RANGE MODELS BEGIN TO DIVERGE BY DAY 4 THEN DRAMATCIALLY BY DAYS 5-7 REGARDING THE TIMING AND LOCATION OF THE MAIN WAVE ROTATING AROUND THE BROAD HUDSON BAY UPPER LOW IN DAYS 5 AND 6. THE 00Z ECMWF IS 12-24 HOURS FASTER THAN THE 00Z GFS IN MOVING THE ATTENDANT SURFACE FRONT THROUGH UPPER MICHIGAN (ALTHOUGH THE 12Z GFS IS A LITTLE FASTER THAN THE 00Z RUN). THE GLOBAL GEM HAS ALSO TRENDED TOWARD THE ECMWF. THE ECMWF MAY BE A LITTLE FAST IN BRINING PCPN BACK INTO THE AREA TUE AFTN...HOWEVER WILL SPEED UP THE TIMING OF PCPN AND INTRODUCE IT INTO THE AREA TUE NIGHT. WILL CONTINUE WITH CHC POPS WED-WED NIGHT...THEN TAPER OFF THU. THE ECMWF ALLOWS THE FRONT TO MOVE TO THE SOUTHERN LAKES BY FRIDAY WHILE THE GFS SUGGESTS WAVE DEVELOPMENT ALONG THE FRONT IN THE CENTRAL PLAINS WHICH WOULD SLOW THE SOUTHWARD PROGRESSION DOWN AND PERHAPS KEEP PCPN NEARBY THURSDAY...BUT FOR NOW WILL OPT TO KEEP IT DRY THU/FRI. NONETHELESS...THE GFS SUGGESTS STRONG ENOUGH RIDGING INTO LAKE SUPERIOR AND UPPER MICHIGAN (AND THE SFC FRONT FAR ENOUGH SOUTH) ON FRIDAY TO KEEP RAIN OUT OF UPPER MICHIGAN FOR NOW. TEMPS WILL REMAIN PLEASANT FOR EARLY JULY...ALTHOUGH THE BEST CHANCE FOR TEMPS IN THE 80S WILL BE ON WED AHEAD OF THE SFC FRONT. WITH 850MB TEMPS ONLY 10-12CFLOW THU AND FRI...TEMPS IN THE 60S AND LOWER 70S WOULD NOT BE SURPRISING...AND HAVE NUDGED TEMPS DOWN SLIGHTLY FOR THOSE PERIODS. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... MULTIPLE ISSUES TO DEAL WITH FOR THIS TAF FORECAST. VISIBLE SATELLITE IMAGES THIS MORNING AND SHIP OBS INDICATE EXTENSIVE FOG ACROSS LAKE SUPERIOR...SOME DENSE WITH VSBY AROUND 1/8SM. ALTHOUGH WINDS HAVE BEEN EASTERLY AT CMX...WHICH WOULD TEND TO BRING THE FOG UP INTO THE KEWEENAW...DAYTIME HEATING APPEARS TO HAVE STOPPED THIS. HOWEVER...WITH HIGH CLOUDS MOVING OVERHEAD AND DIURNAL COOLING THIS EVENING...THINK SOME BR AND MVFR CIG SHOULD DEVELOP LATE THIS AFTN/EVNG. ADDITIONALLY...MID CLOUDS WITH SOME LIGHT RAIN SHOWERS ARE MOVING NE FROM NE WI...WHICH WOULD CROSS CMX LATE THIS AFTN. VFR CONDITIONS EXPECTED AT SAW FOR THE REST OF THIS AFTN...THOUGH A SHOWER OUT OF THE MID CLOUDS COULD MOVE THROUGH LATE THIS AFTN AS WELL. FOR TONIGHT...SHOWERS AND TSRA DEVELOPING OVER NRN MN AND IN ERN NORTH DAKOTA SHOULD MERGE TOGETHER AND EXPAND INTO UPPER MI THIS EVENING...DUE TO TWO UPPER LEVEL DISTURBANCES OVER THE NORTHERN PLAINS MOVING TOWARDS THE AREA. EASTERLY FLOW BRINGING FOG/STRATUS OFF LAKE SUPERIOR WILL HOLD CIGS/VIS AT CMX AT MVFR OR IFR. MVFR CIGS/VIS EXPECTED AT SAW WITH THE PCPN BEING THE MAIN FACTOR BRINGING DOWN THE CIGS/VIS. DEFINITELY NOT ENOUGH CONFIDENCE IN THIS FORECAST TO INCLUDE TS OR VCTS. DRYING ALOFT WORKS IN LATE TONIGHT AT BOTH TAF SITES...WHICH SHOULD ALLOW FOR SOME LIFR/IFR VIS AND LIFR CIGS TO DEVELOP...THANKS TO LINGERING LOW LEVEL MOISTURE FROM PCPN. WEST WINDS AT CMX WILL HOLD THESE LOW CIGS AND VIS IN AT CMX THROUGH TOMORROW MORNING...THOUGH SOME IMPROVEMENT SHOULD OCCUR WITH DAYTIME HEATING. IMPROVEMENT EXPECTED EVEN MORE AT SAW SINCE THE WIND DOWNSLOPES...AND HAVE VIS/CIG RISING TO VFR BY 15Z. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... LOW PRESSURE OVER SE MN WILL LIFT NORTH ACROSS WESTERN LAKE SUPERIOR TONIGHT...THEN MERGE WITH ANOTEHR LOW PRESSURE AREA MOVING EAST OUT OF SE MANITOBA ON SATURDAY. E/SE WINDS WILL INCREASE TO 15 TO 25 KNOTS OVER THE EASTERN 1/2 OF LAKE SUPERIOR TONIGHT...THEN DIMINISH TO BELOW 20 KNOTS ON SATURDAY AS WINDS SWITCH TO THE WEST. THE MERGED SURFACE LOW WILL DROP SOUTH ACROSS LAKE SUPERIOR SATURDAY NIGHT...WITH INCREASING NORTHERLY WINDS BEHIND IT. WINDS MAY APPROACH 30 KNOTS...ESPECIALLY ON EASTERN LAKE SUPERIOR ON SUNDAY AND SUNDAY NIGHT. WINDS WILL DIMINISH TO BELOW 20 KNOTS FOR MONDAY THROUGH WEDNESDAY AS A RIDGE OF HIGH PRESSURE BUILDS ACROSS LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM...AJ LONG TERM...MRD AVIATION...AJ MARINE...AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 147 PM EDT FRI JUN 27 2008 UPDATED AVIATION DISCUSSION FOR 18Z TAF ISSUANCE .SYNOPSIS... WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED A FEW SHRTWVS OF INTEREST FOR THE SHORT TERM...BOTH PRODUCING SOME SHOWERS AND THUNDERSTORMS. THE FIRST IS IN NORTH CENTRAL MN...WITH THE KDLH RADAR DEPICTING SCATTERED -TSRA TO THE WEST AND NW OF DULUTH. THE SECOND IS BACK IN THE DAKOTAS...WITH ACTUALLY A LARGE AREA OF SHOWERS AND EMBEDDED TSRA BETWEEN PIERRE AND ABERDEEN. UPPER MI CURRENTLY UNDER UPPER LEVEL RIDGING...BEING BUILT UP AHEAD OF THE MN SHRTWV AND THE STRONGER UPPER LOW DIGGING DOWN OUT OF SASKATCHEWAN. THIS UPPER RIDGING IS HELPING TO KEEP SKIES PARTLY CLOUDY OVER THE CWA...WITH THE EXCEPTION OF THE FAR WESTERN U.P. WHERE HIGH CLOUDS ARE ENCROACHING. 14Z TAMDAR SOUNDING FROM SAW AND 12Z RAOB FROM GRB DEPICT THE UPPER RIDGE WITH A SUBSIDENCE INVERSION/CAP AROUND 750MB. DRY AIR EVIDENT AS WELL BOTH AT AND BELOW THIS INVERSION...WITH THE GRB SOUNDING SHOWING 925MB DEWPOINT DEPRESSION OF 8C. OTHER ITEM TO NOTE IS THE PERSISTENT FOG OVER LAKE SUPERIOR. SHIP OB JUST CAME IN ABOUT 10 MILES NORTH OF GRAND MARAIS AND SHOWED 1/8SM VSBY. && .UPDATE... TRICKY FORECAST FOR THE AFTERNOON TRYING TO FORECAST TSRA DEVELOPMENT. WITH THE 12Z GRB SOUNDING SHOWING CAPPING AND DRY AIR...AND THE FACT THAT 500MB HEIGHTS DO NOT FALL MUCH TODAY (LIKELY INDICATING CAPPING TO STAY IN PLACE)...THINKING IS AT LEAST THE CENTRAL U.P. WILL NOT SEE MUCH IF ANY PCPN BEFORE 00Z. THE 12Z RUC AGREES WITH THIS ASSESSMENT...WITH SOUNDINGS AT IMT...MQT AND ERY CAPPED WITH TOO MUCH CIN TO OVERCOME (AIDED BY DAYTIME MIXING BRINGING DRIER AIR TO THE SURFACE). THE ONLY PLACE THAT LOOKS GOOD FOR PCPN TO FORM IS IN THE WESTERN U.P....ASSUMING THE HIGH CLOUDS THIN OUT SOME WHICH APPEARS TO BE HAPPENING IN THE LATEST VISIBLE SATELLITE IMAGES. AIRMASS THERE IS A BIT MORE MOIST OVERALL...WHICH SHOULD HOLD THE DEWPOINTS UP. WITH TEMPS GETTING INTO THE MID TO PERHAPS UPPER 70S...AND HEIGHT FALLS APPROACHING LATER IN THE DAY ASSOCIATED WITH THE MN SHRTWV (HELPING TO ELIMINATE CAPPING)... MLCAPES SHOULD APPROACH CLOSE TO 1000 J/KG. THEREFORE...FOR THIS AFTN...MAINTAINED 70 POPS OUT IN THE WEST...AND LOWERED TO 20 IN THE NORTH CENTRAL AND EAST. SVR WX POTENTIAL NOT TOO GREAT...GIVEN 0-6KM SHEAR VALUES BELOW 30 KNOTS. REGARDING THE FOG ON LAKE SUPERIOR...ADJUSTED IT A BIT BASED ON WIND DIRECTION FORECASTS...WHICH SEEM TO MOSTLY FAVOR THE EAST SIDE OF THE KEWEENAW BEING IMPACTED WITH EAST WINDS PICKING UP. ADJUSTED TEMPS SLIGHTLY ALONG THE SHORES BASED ON WIND DIRECTIONS...WITH THE GRAND TRAVERSE BAY SITE ON THE EAST SIDE OF THE KEWEENAW REPORTING 57...BIG BAY AT 61 AND GRAND MARAIS AT 54. ALL THREE SITES SHOULD SEE ONSHORE WIND CONDITIONS THROUGH THE DAY...THUS LOWERED HIGHS AT ALL THREE AREAS. WILL NEED TO ADJUST POPS AFTER 00Z TO DELAY PCPN MOVING INTO THE EASTERN U.P.. STILL THINK THE 70 POPS FOR TONIGHT LOOK GOOD...WITH THE NEXT SHRTWV IN THE DAKOTAS MOVING INTO THE CWA...ALONG WITH ITS ASSOCIATED SHRA AND TSRA. && .DISCUSSION... KIND OF A MESSY PATTERN ACROSS NORTH AMERICA. STRONGEST FEATURE OF NOTE IS A STRONG 500 MB TROUGH ACROSS ALBERTA AND WESTERN SASKATCHEWAN WHICH SHOWS UP AS STRONG DARKENING AND STRONG CYCLONIC ROTATION ON WATER VAPOR. THERE ARE NUMEROUS WEAK SHORTWAVES THAT WERE EITHER CAUSING CONVECTION OR WERE CONVECTIVELY INDUCED ACROSS THE PLAINS AND OHIO RIVER VALLEY. THE NAM TAKES THE TROUGH ACROSS THE CANADIAN ROCKIES AND DIGS IT SOUTHEAST AND FORMS A CLOSED 500 MB LOW WITH IT ACROSS THE CANADIAN PRAIRIES WITH THE TROUGH INTO THE NORTHERN PLAINS 00Z SAT. THE NAM THEN BRINGS THE CLOSED 500 MB LOW INTO THE WESTERN U.P. 00Z SUN AND THEN SLOWLY MOVES IT EAST TO NEAR SAULT STE MARIE 00Z MON AND THEN INTO EASTERN ONTARIO. MEANWHILE...THE NAM BUILDS A STRONG 500 MB RIDGE INTO THE WESTERN U.S. NAM BRINGS IN SOME 850-500 MB Q-VECTOR CONVERGENCE THIS AFTERNOON ACROSS THE WEST HALF WITH PLENTY OF MOISTURE AND Q-VECTOR CONVERGENCE TONIGHT. NAM THEN SHOWS A DRY SLOT MOVING INTO THE AREA ON SAT WITH DYNAMICS DEPARTING AS WELL AS THE CLOSED 500 MB LOW COMES INTO THE AREA. NAM THEN BRINGS BACK IN MOISTURE WITH WRAPAROUND MOISTURE MOVING IN FOR SAT NIGHT AND SUN WITH THE MOISTURE STARTING TO MOVE OUT ON MON. NAM SHOWING SOME ISENTROPIC LIFT ON I300K-I315K SURFACES WITH MOISTURE TONIGHT AND THE MOISTURE MOVES OUT WITH LIFT MOVING OUT ON SAT. GFS IS SIMILAR TO THE NAM AND WILL USE A BLEND OF THE TWO FOR THIS FORECAST. WILL NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST AS CONFIDENCE IN TIMING IS PRETTY LOW ESPECIALLY WITH ANY SHORTWAVE PASSAGE. WILL HAVE LIKELY POPS THIS AFTERNOON AND TONIGHT WITH BEST DYNAMICS MOVING THROUGH ALONG WITH MOISTURE. HAIL LOOKS POSSIBLE ALONG WITH GUSTY WINDS OUT OF ANY THUNDERSTORMS IN THE DRY SLOT SATURDAY AFTERNOON AND ADDED INTO THE FORECAST WITH STEEP LAPSE RATES ACROSS THE AREA. ANY SUNSHINE WILL HELP STRENGTHEN ANY CONVECTION THAT FORMS. DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST EXCEPT LOWERED HIGHS A BIT ON SUNDAY WITH THE UPPER LEVEL LOW IN THE AREA AND COLDER TEMPERATURES ALOFT WHICH WILL DROP TEMPERATURES A BIT AT THE SFC EVEN WITH SOME MIXING. OVERALL...GOING FORECAST WAS GOOD AND MADE VERY FEW CHANGES. FOG WILL CONTINUE OVER LAKE SUPERIOR THROUGH TONIGHT AT LEAST. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... MULTIPLE ISSUES TO DEAL WITH FOR THIS TAF FORECAST. VISIBLE SATELLITE IMAGES THIS MORNING AND SHIP OBS INDICATE EXTENSIVE FOG ACROSS LAKE SUPERIOR...SOME DENSE WITH VSBY AROUND 1/8SM. ALTHOUGH WINDS HAVE BEEN EASTERLY AT CMX...WHICH WOULD TEND TO BRING THE FOG UP INTO THE KEWEENAW...DAYTIME HEATING APPEARS TO HAVE STOPPED THIS. HOWEVER...WITH HIGH CLOUDS MOVING OVERHEAD AND DIURNAL COOLING THIS EVENING...THINK SOME BR AND MVFR CIG SHOULD DEVELOP LATE THIS AFTN/EVNG. ADDITIONALLY...MID CLOUDS WITH SOME LIGHT RAIN SHOWERS ARE MOVING NE FROM NE WI...WHICH WOULD CROSS CMX LATE THIS AFTN. VFR CONDITIONS EXPECTED AT SAW FOR THE REST OF THIS AFTN...THOUGH A SHOWER OUT OF THE MID CLOUDS COULD MOVE THROUGH LATE THIS AFTN AS WELL. FOR TONIGHT...SHOWERS AND TSRA DEVELOPING OVER NRN MN AND IN ERN NORTH DAKOTA SHOULD MERGE TOGETHER AND EXPAND INTO UPPER MI THIS EVENING...DUE TO TWO UPPER LEVEL DISTURBANCES OVER THE NORTHERN PLAINS MOVING TOWARDS THE AREA. EASTERLY FLOW BRINGING FOG/STRATUS OFF LAKE SUPERIOR WILL HOLD CIGS/VIS AT CMX AT MVFR OR IFR. MVFR CIGS/VIS EXPECTED AT SAW WITH THE PCPN BEING THE MAIN FACTOR BRINGING DOWN THE CIGS/VIS. DEFINITELY NOT ENOUGH CONFIDENCE IN THIS FORECAST TO INCLUDE TS OR VCTS. DRYING ALOFT WORKS IN LATE TONIGHT AT BOTH TAF SITES...WHICH SHOULD ALLOW FOR SOME LIFR/IFR VIS AND LIFR CIGS TO DEVELOP...THANKS TO LINGERING LOW LEVEL MOISTURE FROM PCPN. WEST WINDS AT CMX WILL HOLD THESE LOW CIGS AND VIS IN AT CMX THROUGH TOMORROW MORNING...THOUGH SOME IMPROVEMENT SHOULD OCCUR WITH DAYTIME HEATING. IMPROVEMENT EXPECTED EVEN MORE AT SAW SINCE THE WIND DOWNSLOPES...AND HAVE VIS/CIG RISING TO VFR BY 15Z. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... AS HIGH PRESSURE CROSSES LAKE SUPERIOR TODAY WINDS WILL BE LESS THAN 20 KNOTS. AS ANOTHER LOW PRESSURE TROUGH WILL MOVE INTO LAKE SUPERIOR ON TONIGHT AND SATURDAY...PRESSURE GRADIENTS WILL TIGHTEN CAUSING WINDS TO INCREASE TO 20 TO 25 KNOTS FOR A PERIOD OVER CENTRAL AND EAST EASTERN LAKE SUPERIOR. BY LATE SUNDAY NIGHT...THE LOW FILLING SLIGHTLY AND SLIDE SOUTHEASTWARD OVER LOWER MICHIGAN CAUSING THE WINDS TO BE LESS AN 20 KNOTS FOR THE REMAINDER OF THE PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/UPDATE...AJ DISCUSSION...GM AVIATION...AJ MARINE...DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 224 PM CDT FRI JUN 27 2008 .DISCUSSION... MESSY SURFACE PATTERN ACROSS THE REGION THIS AFTERNOON. SURFACE WAVE THAT WAS OVER FAR SOUTHERN MN THIS MORNING HAS PROGRESSED INTO SW WI EARLY THIS AFTERNOON. A TROF STRETCHES SW FROM THE LOW ACROSS CENTRAL IA...WHICH HAS TURNED THE FLOW TO THE WEST. ANOTHER TROF EXTENDS N-S THROUGH CENTRAL AREAS OF THE STATE. CONVECTION HAS DEVELOPED OVER CENTRAL AND NORTHEAST AREAS OF MN NEAR THIS AXIS WHERE HEATING WAS MAXIMIZED. SOME SEVERE STORMS OVER NORTH CENTRAL AND NORTHEAST SECTIONS WHERE 0-1KM AND 0-6 KM SHEAR VALUES ARE 15 AND 30 KNOTS RESPECTIVELY. VERY LITTLE SHEAR ACROSS OUR MN CWA ATTM. SHEAR VALUES ARE PROGGED BY THE RUC TO INCREASE ACROSS CENTRAL AND SOUTHERN MN AND WEST CENTRAL WI DURING THE LATE AFTERNOON AND EVENING HOURS TO VALUES SIMILAR TO THOSE SEEN TO OUR NORTH. 0-3KM CAPE IS ALSO ABOVE 100 J/KG TO OUR NORTH ATTM AND THIS TOO IS PROGGED TO DEVELOP ACROSS EAST CENTRAL MN AND WEST CENTRAL WI. HENCE...SHOWERS AND THUNDERSTORMS THROUGH THE EVENING WITH A FEW SEVERE STORMS. SEVERE THUNDERSTORM WATCH 620 IN EFFECT UNTIL 8 PM. TO OUR WEST AND NORTH...A COLD FRONT STRETCHES FROM FAR NORTHWEST MN THROUGH EASTERN SD AND WILL PUSH EAST OF THE CWA BY MIDNIGHT... BRINING THE SHOWERS AND THUNDERSTORMS TO AN END. A DEEP UPPER LOW OVER SOUTHERN SASKATCHEWAN IS STILL ON TRACK TO ARRIVE OVER THE LOCAL AREA ON SATURDAY. 12HR 400MB HEIGHT FALLS VALID SATURDAY MORNING ARE 180M OVER THE CWA ALONG WITH A HUGE INCREASE IN PV. LIKELY POPS STILL LOOK GOOD FOR TOMORROW ALONG WITH ISOLATED THUNDERSTORMS. IN FACT...THE SHOWERS SHOULD PERSIST WELL INTO THE EVENING BEFORE DIMINISHING. 15Z SREF POPS POINTING TO IMPROVING CONDITIONS ON SUNDAY WITH JUST A SMALL CHANCE FOR SHOWERS OVER FAR EASTERN MN AND WEST CENTRAL WI. HIGH PRESSURE TO BEGIN THE WORK WEEK WHICH SHOULD PREVAIL THROUGH TUESDAY. GREAT COLLABORATION TODAY WITH SURROUNDING OFFICES ON THE WEDNESDAY THROUGH FRIDAY PERIOD. DECIDED TO GO WITH THE ECMWF SOLUTION WHICH WOULD DRIVE A COLD FRONT ACROSS THE FA ON WEDNESDAY WITH DRY WEATHER THURSDAY AND FRIDAY. && .AVIATION... /18Z TAF ISSUANCE/ RAIN SHOWERS ASSOCIATED WITH THE MCV WILL CONTINUE PIVOTING NORTHEAST OF THE TAF SITES THIS AFTERNOON...ALTHOUGH NEW /AND MORE ORGANIZED/ TS/SHRA DEVELOPMENT IS EXPECTED TO ACCOMPANY THE COLD FRONT AS IT PUSHES FROM WESTERN MN TO WEST CENTRAL WI. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO AFFECT KAXN/KRWF EARLY THIS AFTERNOON...AND SPREAD EASTWARD TO KSTC/KMSP/KRNH/KEAU DURING THE MID AFTERNOON AND EARLY EVENING HOURS. EXPECT A PERIOD OF MVFR CONDITIONS TO ACCOMPANY THE TROUGH/FROPA THIS AFTERNOON. WESTERLY WINDS WILL PREVAIL IN THE WAKE OF THE FRONT. STRONG CLOSED MID/UPPER LOW DIVES SOUTHEAST FROM CANADA ON SATURDAY. CU DEVELOPMENT AND SCATTERED SHOWERS ARE EXPECTED TO DEVELOP. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ RAH/LS mn