AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PUEBLO CO 831 PM MDT SAT AUG 2 2008 .UPDATE... WENT AHEAD AND CANCELLED THE RED FLAG WARNING CONSIDERING CRITERIA IS NO LONGER BEING MET OR WILL BE MET ACROSS SOUTHEAST CO PLAINS THIS EVENING. WATER VAPOR IMAGERY AND RUC MODEL UPPER AIR ANALYSES SHOWED THE LARGE HOT HIGH OVER EXTREME SOUTHEASTERN CO WITH A LOW GRADE MOISTURE PLUME FROM AZ INTO WESTERN CO. WILL ANTICIPATE MUCH OF THE CONVECTIVE PRECIPITATION AND DEBRIS CLOUD TO DISSIPATE THIS EVENING AND OVERNIGHT. LIKE MANY SUNRISE...MUCH OF THE AREA SHOULD BE NEARLY CLOUD FREE ONLY TO START THE WHOLE CONVECTIVE PROCESS OVER AGAIN SUNDAY. POTENTIAL FOR NEAR CRITICAL FIRE WEATHER CONDITIONS ACROSS THE FAR SOUTHEASTERN CO PLAINS. MUCH ABOVE AVERAGE TEMPERATURES...LOW HUMIDITY LEVELS...HIGH HAINES...AND EXTREME DROUGHT CONDITIONS WILL BE IN PLACE...EXCEPT THE WIND SPEEDS MAY FALL SHORT OF REACHING THE RED FLAG CRITERIA...SO HELD OFF ISSUING ANOTHER FIRE WEATHER WATCH/RED FLAG WARNING FOR THE FAR SOUTHEAST CO PLAINS AND WILL LET THE MIDNIGHT SHIFT TAKE ANOTHER LOOK AT IT. METZE && .PREV DISCUSSION... /ISSUED 320 PM MDT SAT AUG 2 2008/ SHORT TERM... (TONIGHT AND TOMORROW) ...STILL HOT BUT TRENDING DOWNWARD... CURRENTLY...100+ DEGREE TEMPS ARE COMMONPLACE ACROSS THE PLAINS AS I WRITE. TEMPS ALL ALONG THE LOWER ARK RVR VALLEY ARE IN THE 100S...WITH MANY OTHER AREAS ON THE PLAINS NOT TOO FAR BEHIND. THE MOISTURE PLUME DID WORK A BIT EAST TODAY...AND SOME TSRA/SHRA ARE OCCURRING N OF A LINE FROM THE PIKES PEAK REGION SWWD INTO THE LA GARITA MTNS. REST OF TODAY AND TONIGHT...THE MOISTURE PLUME WILL NOT MOVE ANY FARTHER EAST...LIKEWISE...I DO NOT ANTICIPATE THE PRECIP/VIRGA TO MAKE IT ONTO THE PLAINS. VIRGA MAY COOL THINGS DOWN A BIT ACROSS THE EL PASO COUNTY REGION...BUT THIS COOLING OUTFLOW BOUNDARY SHOULD NOT MAKE IT TOO MUCH FARTHER ONTO THE PLAINS. IT WAS QUITE WARM LAST NIGHT AS PER THE INTERNAL GFE OBSPLOT DATA. ...AND FOR THIS REASON I BUMPED UP MOST OF THE MINS UP A 2-3F. MOST OF THE WARMING WAS ON THE IMMEDIATE EAST SLOPES OF THE ALL THE MTN RANGES. TOMORROW...THE MSTR PLUME IS EXPECTED TO MOVE A BIT TO THE EAST AS THE LARGE HIGH PRESSURE SYSTEM GRADUALLY SHIFTS EAST. POPS IN THE MTNS HAVE BEEN INCREASED ABOUT 10% AND HAVE BEGUN THE PRECIP A BIT EARLIER OVER THE HIGHER TERRAIN. TEMPS WILL ALSO BE A BIT COOLER THAN TODAY ALTHOUGH I STILL ANTICIPATE 100S ACROSS THE LOWER ARK RVR VALLEY. WE MAY ACTUALLY HAVE A BIT MORE OF A SVR WX THREAT TOMORROW AS THE STORMS MOVE OFF THE HIGHER TRRN AND THE PRECIP EVAPORATES. WITH THE DRY AIR STILL IN THE LLVLS WE MAY HAVE TO DEAL WITH SOME DAMAGING WINDS...MAINLY ACROSS PUEBLO...EL PASO AND FREMONT COUNTIES. AS FOR FIRE WX CONCERNS...I BELIEVE THE RED FLAG CONCERNS WILL BE TOO MARGINAL TOMORROW...THAT IS WINDS WILL NOT REACH CRITERIA FOR AN EXTENDED PD OF TIME (3H)...AND IT MAY BE A TAD BIT MORE MOIST IN THE LLVLS. THE BEST THREAT FOR REACHING RED FLAG CRITERIA WOULD BE OVER FAR SE CO. /34 LONG TERM... (SUNDAY NIGHT THROUGH SATURDAY) UPPER RIDGE WILL REMAIN THE DOMINANT FEATURE THROUGH THE EXTENDED...WITH TREND TOWARDS INCREASING PRECIPITABLE WATERS AND COOLING TEMPERATURES FOR TUESDAY THROUGH SATURDAY AS A SERIES OF SHORTWAVES MOVES THROUGH THE NRN ROCKIES/NRN PLAINS SENDING WEAK COLD FRONTS THROUGH THE SE PLAINS. TIMING OF THESE S51OW COLD FRONTS WILL BE THE BIGGEST FORECAST C51ENGE. MONDAY STILL LOOKS FAIRLY HOT ACROSS THE AREA AHEAD OF THE FIRST S51OW FRONT WITH H7 TEMPS STILL RANGING FROM +17 TO +20C ACROSS THE AREA. THIS WILL YIELD MID 90S TO LOWER 100S ACROSS THE PLAINS WITH 70S AND 80S FOR THE MOUNTAINS. WITH MONSOON PLUME STILL OVERHEAD...ISO TO SCT POPS EXPECTED...A FEW OF WHICH MAY DEVELOP/SPREAD ACROSS THE ADJACENT PLAINS. ALTHOUGH PRECIP WATERS ARE SLOWLY COMING UP IN THE WEST...LOW LEVELS ARE STILL QUITE DRY THIS DAY...SO THE MAIN THREAT WITH STORMS WILL BE GUSTY WINDS AND LIGHTNING...WITH A FEW FIRE STARTS POSSIBLE...ESPECIALLY ACROSS THE SOUTHEAST PLAINS. HOWEVER WITH INCREASED CONVECTIVE CLOUD COVER...THIS MAY HELP TO HOLD BACK TEMPS A COUPLE MORE DEGREES ACROSS THE ADJACENT PLAINS. FIRST S51OW FRONT MAKES A PUSH INTO SE CO MON NIGHT...LIKELY AIDED BY CONVECTIVE OUTFLOW FROM NOCTURNAL CONVECTION WHICH DEVELOPS ACROSS NE CO. THIS SHOULD TAKE THE EDGE OFF MAX TEMPS FOR TUESDAY AS SFC DEW POINTS INCREASE ACROSS THE PLAINS. MEANWHILE...PRECIP WATERS CONTINUE TO GRADUALLY INCREASE ACROSS WRN AREAS BENEATH MONSOON MOISTURE TAP. THUS...TUES SHOULD SEE AN INCREASED CHANCE FOR PRECIPITATION FOR JUST ABOUT EVERYWHERE. DEPENDING ON AMOUNT OF LOW LVL MOISTURE RETURN...COULD SEE CAPES APPROACH 1500 J/KG ACROSS THE PLAINS. WITH WEAK DEEP LAYER SHEARS...HEAVY RAIN WILL BE THE PRIMARY THREAT WITH STORMS...THOUGH COULDN`T RULE OUT SOME SMALL HAIL AND WIND GUSTS TO 50 MPH. NOT MUCH CHANGE FOR THE REMAINDER OF THE EXTENDED...WITH WED STILL UNDER THE MONSOON PLUME. TEMPS MAY WARM A FEW DEGREES ACROSS THE PLAINS AS LOW LVL FLOW BECOMES MORE SOUTHERLY INSTEAD OF EASTERLY. DEW POINTS DECREASE ALONG THE I-25 CORRIDOR AS S51OW MOIST LAYER MIXES OUT. THE NEXT FRONT DROPS THROUGH THE SE PLAINS WED NIGHT/EARLY THURS WITH ANOTHER COOL DOWN AND POSSIBLE INCREASE IN PRECIPITATION CHANCES FOR THURS. FRIDAY AND SATURDAY WENT CLOSER TO CLIMO. STILL HAVE THE MONSOON MOISTURE TAP OVER THE REGION...WITH LONG RANGES MODELS SUGGESTING A STRONGER PUSH OF COOLER AIR MAY MAKE IT INTO THE SE PLAINS BY NEXT SATURDAY. AMOUNT OF COOL DOWN WILL BE DEPENDED ON HOW FAR WEST THE UPPER TROF AND ASSOC SFC HIGH DROPS ROTATES THROUGH THE GREAT LAKES REGION/NRN HIGH PLAINS. THIS IS BOUND TO CHANGE FROM RUN TO RUN. FOR NOW HAVE GONE WITH TEMPS AROUND TO SLIGHTLY ABOVE CLIMO WITH THE TYPICAL DIURNAL SCT TO ISO AFTN POPS. -KT AVIATION...VFR CONDITIONS EXPECTED ACROSS KCOS...KPUB AND KALS NEXT 24H. MAIN CONCERN WILL BE FOR A SLIGHT CHANCE OF VERY GUSTY WINDS AT KCOS THIS AFTERNOON DUE TO VIRGA...WITH A MUCH BETTER CHANCE OF STRONG GUSTY WINDS ACROSS KCOS TOMORROW AFTERNOON ONCE AGAIN DUE TO VIRGA/TSRA. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 17/17 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 318 PM MDT SAT AUG 2 2008 .SHORT TERM...TONIGHT THROUGH MONDAY... A LINE OF SHOWERS WITH ISOLATED EMBEDDED THUNDERSTORMS FORMED SOUTHEAST OF A WEAK JETLET EXTENDING FROM NEAR GREEN RIVER TO NORTHWEST OF KCAG. MEANWHILE...WIDELY SCATTERED TO ISOLATED THUNDERSTORMS HAVE ERUPTED OVER MUCH OF THE HIGHER TERRAIN OF WESTERN COLORADO EARLY THIS AFTERNOON. RUC ANALYSES AND SATELLITE IMAGERY SHOWED MONSOONAL STREAM HAD MOVED IN OVERNIGHT FUELING THE ACTIVITY DISCUSSED ABOVE. KGJT MORNING SOUNDING DATA HAD JUMPED TO NEAR 0.75 INCHES PW AND DEW POINTS WERE UP 3 TO 5 DEGREES ACROSS THE AREA. THOUGH DEW POINTS HAVE INCREASED...LOWER LEVELS STILL RELATIVELY DRY. TOO DRY...IN FACT...TO PRODUCE HEAVY RAIN THOUGH STORM MOTION SUFFICIENTLY SWIFT TO MINIMIZE RISK OF STRONG DOWNPOURS ANYWAY. UPPER LEVEL SUPPORT WILL DECLINE BY SUNSET...SO EXPECT NORMAL DIURNAL DECREASE IN THUNDERSTORM ACTIVITY THIS EVENING WITH LITTLE CHANCE OF NOCTURNAL STORMS OVERNIGHT. SLIGHT DRYING INDICATED FOR EASTERN UTAH SUNDAY...OTHERWISE EXPECT ANOTHER ROUND OF AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS FAVORING HIGHER TERRAIN OF WESTERN COLORADO...ESPECIALLY SOUTH. SLIGHT SHIFT IN PATTERN INDICATED FOR MONDAY AS MODELS STEER THE HIGH PRESSURE CENTER TO CENTRAL COLORADO. THIS WILL BRING DRYING TO THE NORTH WHICH WILL RESULT IN DECREASED ACTIVITY. SOUTH WILL REMAIN RELATIVELY MOIST...THUS THUNDERSTORMS WILL BE MORE NUMEROUS. TEMPERATURES WILL CONTINUE TO MODERATE UNDER THIS PATTERN...THOUGH WILL LIKELY REMAIN ABOVE NORMAL DURING THE PERIOD. .LONG TERM...MONDAY NIGHT THROUGH SATURDAY... MODELS HAVE BEEN CONSISTENT WITH A GOOD MONSOONAL MOISTURE SURGE FOR THESE PERIODS...EVEN INTO THE NORTHERN ROCKIES. THE ALL IMPORTANT DETAILS STILL REMAIN UNCERTAIN. BUT THURSDAY +/- 1 DAY HAS BEEN CONSISTENTLY SHOWN AS THE BEST CHANCE FOR SHOWERS AND STORMS. STORM MOTION OF WEST 5-10MPH THRU THESE PERIODS SUPPORTS POTENTIAL HEAVY SHOWERS. WETBULB-ZERO LEVEL IS UP AROUND 16KFT MSL WHICH DOES NOT ELIMINATE HAIL POSSIBILITY...BUT MAKES LARGE HAIL UNLIKELY IN THE VALLEYS. TEMPERATURES WILL BE NEAR TO SLIGHTLY ABOVE NORMAL. WINDS WILL BE TERRAIN AND STORM DRIVEN. && .AVIATION...SCATTERED THUNDERSTORMS WILL DIMINISH TO ISOLATED AFTER SUNSET TONIGHT. LOCAL MVFR CONDITIONS ARE POSSIBLE THIS EARLY EVENING IN BRIEF HEAVY RAIN OR SMALL HAIL. WIND GUSTS TO 40 MPH ARE ALSO POSSIBLE. SUNDAY...THUNDERSTORMS WILL AGAIN FORM FIRST OVER THE MOUNTAINS IN THE EARLY AFTERNOON...MOVING OVER THE VALLEYS BY LATE AFTERNOON. && .GJT WATCHES/WARNINGS/ADVISORIES... .CO...NONE. .UT...NONE. $$ SHORT TERM.....NL LONG TERM......JOE AVIATION.......JOE co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 344 AM MDT SAT AUG 2 2008 .SHORT TERM... (TODAY AND TONIGHT) SHORT TERM CONCERNS INCLUDE HIGH BASED CONVECTION COVERAGE ALONG WITH THE POTENTIAL FOR CRITICAL FIRE WEATHER CONDITIONS. CURRENT WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSIS INDICATING CENTROID OF LARGE 595DM UPPER HIGH SLOWLY DRIFTING SOUTH AND EAST ACROSS SOUTH CENTRAL AND SOUTHEAST COLORADO AS A BROAD UPPER TROUGH ACROSS THE PAC NORTHWEST COAST IS CURRENTLY TRAVERSING ACROSS THE NORTHERN TIER ATTM. WATER VAPOR IMAGERY IS ALSO INDICATING INCREASED ATMOSPHERIC MOISTURE EMBEDDED WITHIN THE WEAK SW FLOW ACROSS DESERT SW THROUGH THE GREAT BASIN ALONG WITH A FEW SHORT WAVES EJECTING OUT AHEAD OF THE PAC NW TROUGH ACROSS THE GREAT BASIN AND NORTHERN ROCKIES ATTM. TODAY-TONIGHT...MODELS REMAIN CONSISTENT WITH SLOWLY DRIFTING THE CENTROID OF THE UPPER HIGH SOUTH AND EAST ACROSS THE SOUTHEAST PLAINS THIS AFTERNOON AND INTO THE SOUTHERN AND CENTRAL HIGH PLAINS OVERNIGHT...AS BROAD UPPER TROUGH CONTINUES TO RIDE THE PERIPHERY OF THE RIDGE ACROSS THE NORTHERN ROCKIES THROUGH TONIGHT. WITH MID AND UPPER LEVEL MOISTURE EMBEDDED IN THE DEVELOPING WEAK SOUTHWEST FLOW ALOFT ACROSS THE AREA ALONG WITH STRONG SOLAR HEATING AND SOME INCREASED UVV ASSOCIATED WITH PASSING SHORT WAVES...SHOULD SEE A SLIGHT INCREASE IN MAINLY HIGH BASED CONVECTION ACROSS THE MOUNTAINS AND IMMEDIATE ADJACENT PLAINS THIS AFTERNOON AND EVENING. MODEL SOUNDINGS INDICATING INVERTED V PROFILES WITH MODEST ELEVATED CAPES AND WOULD EXPECT MAINLY DRY THUNDERSTORMS...PRODUCING GUSTY WINDS TO AROUND 40 MPH WITH LITTLE RAIN...ESPECIALLY ACROSS THE EASTERN MTS AND IMMEDIATE ADJACENT PLAINS. BEST COVERAGE OF WETTING RAINFALL...IF ANY...LOOKS TO REMAIN ACROSS THE SW AND CENTRAL MTS WITH PWATS PROGGED TO INCREASE TO BETWEEN .5 AND .75 INCHES. ALL CONVECTION LOOKS TO DIMINISH THROUGH THE EARLY EVENING WITH THE SETTING OF THE SUN. MODELS ALSO REMAIN CONSISTENT WITH WEAK LEE TROUGHING ACROSS THE I-25 CORRIDOR THROUGH THE EVENING...KEEPING BEST GRADIENT AND GUSTY SOUTH WINDS OF 20 TO 30 MPH ACROSS THE FAR SE PLAINS. THE WINDS...ALONG WITH MIN RHS AROUND 10 PERCENT AND DRY FUELS ALL POINT TO ANOTHER ROUND OF CRITICAL FIRE WEATHER CONDITIONS ACROSS THE FAR SE PLAINS...AND WILL KEEP CURRENT RED FLAG WARNING IN TACT FOR THIS AFTERNOON AND EARLY EVENING. AS FOR TEMPERATURES...WITH SOME INCREASE IN CONVECTIVE CLOUD COVER EXPECTED...HAVE GONE WITH HIGHS AT OR SLIGHTLY BELOW YESTERDAYS READINGS...WITH MID 90S TO MID 100S ACROSS THE PLAINS. -MW .LONG TERM... (SUNDAY THROUGH FRIDAY) ON SUN THE UPR RIDGE WL BE CENTERED OVR THE CENTRAL PLAINS STATES AND A WEAK SHRTWV IS EXPECTED TO MOVE ACRS THE FORECAST AREA. PW VALUES ARE FORECAST TO INCREASE FOR SUN...RANGING FROM 0.6 OVR THE CENTRAL MTS TO OVR AN INCH OVR THE SERN PLAINS. TEMPS SUN WL STILL BE ABOVE NORMAL...WITH HIGHS IN THE MID 90S TO LOWER 100S ON THE SERN PLAINS AND MID 80S TO LOWER 90S OVR THE HIGH VALLEYS. REGARDING FIRE WEATHER CONDITIONS...WINDS DO NOT LOOK LIKE A PROBLEM MOST AREAS SUN...BUT COULD BE MARGINAL OVR THE FAR SERN PLAINS...HOWEVER THE MIN RH ALSO LOOKS MARGINAL IN THAT AREA...THUS WL NOT ISSUE ANY HIGHLIGHTS AT THIS TIME. NOT MUCH CHANGE FOR MON ALTHOUGH PW VALUES ARE EXPECTED TO INCREASE A LITTLE MORE OVR THE ERN HALF OF THE FORECAST AREA. TEMPS WL STILL BE VERY WARM...AND ISOLD TO SCT PCPN CAN BE EXPECTED WITH THE BEST CHANCES OVR THE MTS. TUE A SHRTWV TROF MOVE INTO NE AND THE UPR RIDGE BUILDS BACK UP OVR THE WRN STATES. WITH THE PASSAGE OF THAT SHRTWV A FRONT MOVES INTO ERN CO...AND TEMPS SHOULD BE A LITTLE COOLER ALTHOUGH THE FRONTAL TIMING REMAINS AN ISSUE. PW VALUES ARE FORECAST TO INCREASE A LITTLE MORE AND PCPN CHANCES WL PROBABLY BE A LITTLE HYR. WED THE UPR RIDGE CENTER IS EXPECTED TO BE OVR THE FOUR CORNERS REGION...BUT STILL PLENTY OF MSTR FORECAST TO BE OVR THE AREA. THE UPR RIDGE WL LIE OVR CO THU AND FRI...WITH PW VALUES A BIT LOWER...BUT THERE WL STILL BE ENOUGH MSTR OVR THE AREA TO AT LEAST SEE SCT POPS OVR THE MTS. && .AVIATION...ISOLATED HIGH BASED THUNDERSTORMS EXPECTED OVER AND NEAR THE MOUNTAINS BETWEEN 18Z-03Z. STORMS WILL PRODUCE MAINLY GUSTY AND ERRATIC WINDS UP TO 45 MPH AND A FEW CLOUD TO GROUND LIGHTNING STRIKES...WITH BRIEF MVFR CIGS POSSIBLE NEAR STORMS. OTHERWISE... VFR CONDITIONS ARE EXPECTED THROUGH TONIGHT. WITH CONTINUED VERY WARM CONDITIONS...PRESSURE ALTITUDES AND DENSITY ALTITUDES ISSUES WILL BE POSSIBLE. -MW && .PUB WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING FROM NOON TODAY TO 9 PM MDT THIS EVENING FOR COZ231>237. && $$ 23/28 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 830 PM EDT FRI AUG 1 2008 .SYNOPSIS/UPDATE... 00Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING A BIT MORE AMPLIFIED AN UPPER PATTERN ACROSS NORTH AMERICA THAT ONE WOULD EXPECT DURING EARLY AUGUST. HOWEVER...THIS IS JUST HOW THE SUMMER HAS GONE...ESPECIALLY IN THE EAST WITH THE NORTHERN STREAM FLOW STRUGGLING TO FIND A ZONAL PATTERN. CURRENTLY FROM WEST TO EAST WE FIND AN IMPRESSIVE TROUGH ALONG THE WEST COAST OF CANADA DOWN INTO THE PACIFIC NORTHWEST. THE FLOW THEN RIDGES UP AND OVER THE DOMINANT RIDGE CENTER ACROSS MUCH OF THE WEST. FINALLY WE SEE THE NORTHERN STREAM DIVE BACK INTO LONGWAVE TROUGHING COVERING MUCH OF THE EASTERN THIRD OF THE NATION. A WEAKER EXTENSION OF THIS TROUGH CAN BE ANALYZED ALL THE WAY DOWN TO THE NORTHEASTERN GULF OF MEXICO. IT WAS THIS UPPER LEVEL SUPPORT THAT AIDED AN ALREADY WET SOUTHWEST FLOW REGIME TO PRODUCE WIDESPREAD SHOWER AND THUNDERSTORMS COVERAGE ACROSS OUR AREA FROM LATE THIS PAST MORNING INTO THIS EVENING. AT THE SURFACE...THE FORECAST AREA REMAINS BETWEEN A WEAK TROUGH EXTENDING ACROSS CENTRAL GA INTO EAST-CENTRAL AL AND THE SUBTROPICAL RIDGE TO OUR SOUTH. SHOWER AND THUNDERSTORMS INTENSITY HAS CERTAINLY DIMINISHED BUT STILL SEEING SCATTERED SHOWERS AROUND THE AREA. AN AREA OF LIGHT STRATIFORM RAINS LEFT BEHIND FROM EARLIER THUNDERSTORMS AND PRESENTLY LOCATED FROM NORTH OF PANAMA CITY INTO SOUTHWEST AND SOUTH-CENTRAL GA WILL CONTINUE TO DISSIPATE OVER THE NEXT COUPLE OF HOURS. DESPITE THE LOSS OF DIURNAL HEATING...THE MID-LEVEL TROUGH WILL SUPPORT THE CONTINUED DEVELOPMENT OF WIDELY SCATTERED CONVECTION FOR THE REMAINDER OF THE EVENING. THE FORECAST WILL BECOME COMPLICATED OVERNIGHT AS A PIECE OF MID-LEVEL ENERGY JUST TO OUR WEST SETTLES SOUTH INTO THE NORTHEAST GULF OF MEXICO. THERE IS SOME GUIDANCE CONSENSUS ON THIS ENERGY RESULTING IN WEAK CYCLOGENESIS ALONG THE PANHANDLE COAST OR JUST TO THE SOUTH LATER TONIGHT INTO EARLY SATURDAY. THIS MAKES THE POP FORECAST DIFFICULT...ESPECIALLY ALONG THE COAST. SO FOR THE REST OF THE NIGHT WILL ALLOW THE SHOWERS AND STORMS TO END AFTER MIDNIGHT ALONG AND NORTH OF I-10...HOWEVER EXPECTING NUMEROUS SHOWERS/STORMS TO REDEVELOP ACROSS THE COASTAL WATERS WITH AT LEAST SOME OF THESE EFFECTING THE COASTAL COUNTIES. THE MOST LIKELY PLACES TO SEE A WETTER SECOND HALF OF THE NIGHT WOULD BE ALONG THE PANHANDLE COAST AND THEN EXTENDING EAST INTO FRANKLIN AND DIXIE COUNTIES OF THE FLORIDA BIG BEND. .AVIATION...VFR CEILINGS IN A MID LEVEL DECK WILL PREDOMINATE UNTIL 08Z AFTER WHICH TIME MVFR CEILINGS AND VSBY SHOULD DEVELOP. CONFIDENCE IS HIGHEST FOR MVFR AT ABY AND VLD WHERE IT IS THE PREVAILING CONDITIONS...TEMPOS ELSEWHERE. SHOWERS WILL START EARLY ONCE AGAIN ON SAT...AS EARLY AS 09Z AT PFN AND 13-14Z AT TLH. LOOK FOR GENERALLY MVFR CONDITIONS IN TS WITH BRIEF PERIODS OF IFR. IT SHOULD BE NOTED THAT BOTH THE NAM AND GFS INSIST ON DEVELOPING LOW PRESSURE NEAR AAF SAT MORNING. WE BELIEVE THIS IS A BIT OVERDONE. HOWEVER...IF A LOW DOES DEVELOP...WIND SPEEDS AND RAIN CHANCES WILL BE HIGHER THAN INDICATED IN THE TAFS AT TLH AND VLD. && .PREVIOUS DISCUSSION... .SHORT TERM...SATURDAY THROUGH SUNDAY NIGHT...SHORT TERM MODELS SHOW THE UPPER TROUGH OVER THE EASTERN U.S. AMPLIFYING THROUGH SATURDAY AND THEN RETREATING ON SUNDAY AS UPPER RIDGING STARTS TO BUILD BACK IN. THE GFS CONTINUES TO SHOW A LOW CLOSING OFF ALONG THE GULF COAST. THE PREVIOUS RUN CLOSED THE LOW NEAR NEW ORLEANS AND NOW OVER THE FLORIDA PANHANDLE. THE NAM SHOWS A SHORT WAVE WITH A DECENT VORT IN THE SAME VICINITY BUT DOES NOT CLOSE OFF A LOW. THE GFS WINDS AND CERTAINLY QPF FOR SATURDAY WILL BE DISCOUNTED. EITHER WAY...BOTH MODELS SHOW THE SURFACE TROUGH PUSHING CLOSER TO OUR CWA BY SATURDAY AFTERNOON AND SOME MID LEVEL DRY AIR FILTERING INTO OUR ALABAMA AND MOST GEORGIA ZONES. WILL TAPER POPS LOWER END CHANCE NORTH TO LIKELY ACROSS ALL OUR FLORIDA ZONES. ON SUNDAY...OUR FA WILL BE ON THE BACKSIDE OF THE EXITING UPPER TROUGH WITH ADDITIONAL DRY AIR FILTERING IN OVER OUR NORTHERN AND WESTERN ZONES. THE SURFACE WINDS WILL REMAIN OUT OF THE SOUTHWEST TO WEST KEEPING THE LOWER LEVELS MOIST. THE SURFACE TROUGH WILL ALSO LINGER OVER OR JUST NORTH OF OUR NORTHERNMOST ZONES. WILL SHOW THE HIGHEST POPS OVER THE BIG BEND. && .LONG TERM...ON MONDAY...THE SURFACE RIDGE AXIS WILL REMAIN OVER SRN FL WITH A TROUGH OVER THE SE, WITH NEAR CLIMO POPS (BEST CHANCES OVER FL ZONES). BOTH THE GFS/EURO SHOW THE MID/UPPER LOW OVER THE NERN GOMEX AND SURFACE REFLECTION DRIFTING WWD TUESDAY. THIS WILL ALLOW THE SURFACE RIDGE TO SHIFT NWD INTO NRN/CNTRL FL. ALSO...THE MODELS INDICATE MID/UPPER RIDGING TO THE NW BUILDING INTO THE SE WEDNESDAY, WITH DRIER AIR FILTERING INTO THE REGION. THE RESULT WILL BE A LOWERING OF POPS TO BELOW CLIMO AND TEMPS WARMING A FEW DEGREES ABOVE CLIMO. ON THURSDAY...THE GFS SHOWS THE RIDGE BREAKING DOWN... WHILE THE EURO MAINTAINS THE RIDGE. BY FRIDAY...MOISTURE INCREASES AND POPS/TEMPS RETURN TO CLIMO. && .MARINE...A RIDGE OF HIGH PRESSURE TO THE SOUTH AND AN APPROACHING TROUGH OF LOW PRESSURE FROM THE NORTH WILL TIGHTEN THE PRESSURE GRADIENT AND ELEVATE WINDS TO CAUTIONARY LEVELS TONIGHT INTO SATURDAY. WINDS DIMINISH BELOW HEADLINE CRITERIA BY SATURDAY AFTERNOON. WINDS AND SEAS SHOULD STAY LOW SUNDAY INTO AT LEAST EARLY NEXT WEEK AS A RIDGE OF HIGH PRESSURE BUILDS IN FROM THE EAST. && .FIRE WEATHER...NO CONCERNS. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 74 88 74 90 74/ 50 70 40 50 40 PANAMA CITY 76 88 78 90 77/ 50 60 40 40 30 DOTHAN 72 91 74 92 75/ 50 40 30 40 20 ALBANY 73 93 75 92 74/ 30 50 30 40 20 VALDOSTA 73 89 72 88 76/ 40 60 40 50 30 CROSS CITY 74 87 73 88 73/ 40 70 40 40 40 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. GM...NONE. && $$ AVIATION...WOOL LONG TERM...JAMSKI SHORT TERM...BARRY SYNOPSIS/UPDATE...MROCZKA fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 739 PM EDT SAT AUG 2 2008 .SYNOPSIS... A WEAK UPPER TROUGH THIS WEEKEND WILL GIVE WAY TO AN UPPER RIDGE THROUGH THE FIRST HALF OF NEXT WEEK. A COLD FRONT WILL APPROACH THE REGION LATE NEXT WEEK INTO NEXT WEEKEND. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... SPC HAS ISSUED SEVERE THUNDERSTORM WATCH NUMBER 796 UNTIL 1 AM FOR THE INLAND ZONES FROM ALLENDALE COUNTY UP THROUGH BERKELEY COUNTY. WE MAY OPT TO EXPAND THE WATCH FARTHER SOUTH AND EAST DEPENDING ON HOW CONVECTION EVOLVES OVER THE NEXT SEVERAL HOURS. RUC FORECAST SOUNDINGS SUPPORT ONGOING VISIBLE SATELLITE TRENDS OF DEPICTING A STRONGLY CAPPED ENVIRONMENT. CONVECTION CONTINUES ORGANIZE UPSTREAM WHERE UVM ASSOCIATED WITH THE TAIL END OF A SHORTWAVE MOVING THROUGH THE MID-ATLANTIC IS TRAILING SOUTH THROUGH THE NORTHERN MIDLANDS...THE UPSTATE AND NORTHERN GEORGIA. THIS ACTIVITY COULD MAKE A RUN FOR SOUTHERN SOUTH CAROLINA AND POSSIBLY PORTIONS OF SOUTHEAST GEORGIA LATER THIS EVENING OR EARLY SUNDAY MORNING BUT THIS WILL BE HIGHLY DEPENDANT ON THE DEGREE OF CONVECTIVE ORGANIZATION THAT OCCURS OVER THE NEXT FEW HOURS. ATTM IT APPEARS THE GREATEST CHANCES FOR SHOWERS AND THUNDERSTORMS WILL REMAIN ACROSS INLAND SOUTHEAST SOUTH CAROLINA FROM COLLETON COUNTY NORTH THROUGH BERKELEY COUNTY. HAVE UPDATED OUR POP...CLOUD AND TEMPERATURE GRIDS TO DEPICT ONGOING SHORT TERM TRENDS. THE HEAT ADVISORY FOR TODAY HAS EXPIRED. A NUMBER OF LOCATIONS THROUGHOUT THE ADVISORY AREA SAW HEAT INDEX VALUES OF 105-110 FOR SEVERAL HOURS. SHOULD SEE SIMILAR CONDITIONS AGAIN SUNDAY WHERE ANOTHER HEAT ADVISORY IS ALREADY IN EFFECT. BASED ON HEAT INDEX/DEWPOINT TRENDS OBSERVED THIS AFTERNOON AND OUTPUT FROM THE 18Z MODELS...HAVE OPTED TO EXTEND THE HEAT ADVISORY INTO INLAND COLLETON COUNTY. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... THE COMBINATION OF HIGH TEMPERATURES IN THE MID 90S AND DEWPOINTS IN THE MID TO UPPER 70S WILL CREATE HEAT ADVISORY CONDITIONS ACROSS AT LEAST THE CHARLESTON TRI-COUNTY AREA SW THROUGH CHATHAM COUNTY. CONFIDENCE IN THIS SCENARIO WAS SUFFICIENT TO JUSTIFY A HEAT ADVISORY FOR THE NOON-7 PM PERIOD SUNDAY WHERE HEAT INDEX VALUES COULD REACH IN THE 106-112 DEGREE RANGE. FARTHER S/W...UNCERTAINLY ABOUT MORNING CLOUD COVER AND AFTERNOON DEWPOINTS...WHICH MAY FALL INTO THE UPPER 60S INLAND...PRECLUDES ANY NEW HEAT ADVISORY HEADLINES IN THIS PACKAGE. MEANWHILE...THE REGION WILL REMAIN UNDER WEAK TROUGHING AT THE SURFACE AND ALOFT. DRY/WARM MID LEVEL AIR AND THE ASSOCIATED CAP MAY ONCE AGAIN DELAY THE ONSET OF DEEP MOIST CONVECTION UNTIL WELL INTO THE AFTERNOON. HOWEVER...ISOLATED TO SCATTERED THUNDERSTORMS SHOULD EVENTUALLY DEVELOP...WITH THE BEST COVERAGE WITHIN SLIGHTLY DEEPER MOISTURE/A SLIGHTLY WEAKER CAP ACROSS SE GA...ESPECIALLY NEAR THE SEA BREEZE. GIVEN STRONG INSTABILITY AND MID LEVEL DRY AIR...BRIEF PULSE SEVERE THUNDERSTORMS CANNOT BE RULED OUT. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... SHOWERS AND WEAK THUNDERSTORMS COULD LINGER ACROSS INLAND AREAS FOR A FEW HOURS AFTER SUNSET SUNDAY NIGHT...HOWEVER COVERAGE WILL QUICKLY DIMINISH WITH THE LOSS OF DAYTIME INSTABILITY AND SEABREEZE FORCING. THE FORECAST AREA WILL REMAIN ON THE WESTERN PERIPHERY OF ATLANTIC HIGH PRESSURE THROUGH THE EXTENDED PERIOD...WHILE A PERSISTENT SURFACE TROUGH REMAINS ACROSS THE INLAND CAROLINAS. THE PATTERN WILL BE TRANSITIONING ALOFT...AS STRONG UPPER LEVEL RIDGING CENTERED OVER THE CENTRAL AND SOUTHERN PLAINS EXPANDS EASTWARD THROUGH MID WEEK. EXPECT A SIGNIFICANT HEATING TREND MONDAY THROUGH WEDNESDAY...WITH HIGH TEMPERATURES ON WEDNESDAY NEAR 100 DEGREES IN THE FAR INLAND COUNTIES. AFTERNOON DEWPOINTS WILL REMAIN IN THE MID 70S FOR MUCH OF THE REGION...LEADING TO UNCOMFORTABLE LEVELS OF HEAT AND HUMIDITY. HEAT ADVISORIES ARE POSSIBLE FOR MONDAY AND TUESDAY...WHILE A HEAT ADVISORY IS LIKELY ON WEDNESDAY WHEN HEAT INDICES RISE TO 107 TO 110 DEGREES. STRONG UPPER RIDGING THROUGH WEDNESDAY SUGGESTS THAT THUNDERSTORM DEVELOPMENT WILL MAINLY BE DIURNAL IN NATURE...DRIVEN BY TYPICAL SUMMERTIME INSTABILITY AND SEABREEZE FORCING. FORECAST SOUNDINGS INDICATE PWAT VALUES AROUND 1.5 INCHES...AND DEEP LAYER MOISTURE APPEARS LIMITED THROUGH MID WEEK. THUS WILL MAINTAIN ONLY SLIGHT CHANCE POPS DURING THE AFTERNOON AND EVENINGS...SLIGHTLY BELOW CLIMATOLOGY. AN UPPER LOW WILL DROP INTO THE GREAT LAKES REGION THURSDAY...ALLOWING THE BROAD UPPER TROUGH TO PRESS SOUTHWARD AND LOWER HEIGHTS OVER THE MID ATLANTIC AND SOUTHEAST. A WEAK SURFACE FRONT WILL ALSO PUSH SOUTHEAST AND PERHAPS LINGER NEAR THE FORECAST AREA ON THURSDAY. AS WEAK UPPER TROUGHING BECOMES RE-ESTABLISHED ACROSS THE SOUTHEAST STATES...EXPECT HIGH TEMPERATURES TO RETURN TO THE LOWER TO MID 90S BY THE END OF THE WEEK. HAVE ALSO INCREASED THE CHANCE OF AFTERNOON CONVECTION TO AROUND 30 PERCENT AWAY FROM THE COASTLINE. MODELS INDICATE ANOTHER FRONT DESCENDING TOWARD THE REGION OVER THE WEEKEND...BUT THERE CONTINUES TO BE SOME DISAGREEMENT IN THE DETAILS. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... LOW LEVEL JET ALOFT WILL ALLOW SOUTHWESTERLY WINDS TO BE AT OR BELOW 10 KNOTS OVERNIGHT AT THE TERMINALS. HOWEVER...BRIEF MVFR VISIBILITIES MAY DEVELOP ESPECIALLY AROUND THE KSAV AIRPORT DUE TO SOMEWHAT LIGHTER WINDS IN THAT AREA THAN AT KCHS. SEA BREEZE IS EXPECTED TO BE LATE PUSHING INTO BOTH AIRPORTS SUNDAY AFTERNOON AS IT WILL BE PINNED ALONG THE COAST DUE TO STRONG WEST SOUTHWEST WINDS AT THE SURFACE. HAVE INTRODUCED CBS AT BOTH TAF SITES FOR SUNDAY AFTERNOON AS WE EXPECT SHOWER AND THUNDERSTORM ACTIVITY TO AGAIN DEVELOP ACROSS THE AREA. EXTENDED AVIATION OUTLOOK...BUILDING HEAT AND HUMIDITY THROUGH MID WEEK WILL INCREASE THE POTENTIAL FOR AFTERNOON MVFR HAZE CONDITIONS AND OVERNIGHT MVFR MIST AND HAZE. OTHERWISE...VFR CONDITIONS WITH SLIGHT CHANCES OF AFTERNOON TSTMS EACH DAY. && .MARINE... A COMBINATION OF LATE AFTERNOON/EARLY EVENING SEA BREEZE ENHANCEMENT AND NOCTURNAL SURGING OF S/SW WINDS. THE POTENTIAL FOR SUSTAINED WINDS AROUND 20 KNOTS AND OCCASIONAL GUSTS TO 25 KNOTS JUSTIFIES A SMALL CRAFT ADVISORY FOR ALL MARINE ZONES. THE ADVISORY WILL EXPIRE AT MIDNIGHT FOR CHARLESTON HARBOR AND THE GEORGIA NEARSHORE WATERS...WHERE WINDS SHOULD DIMINISH EARLIER. FOR THE REMAINDER OF THE COASTAL WATERS...CARRIED THE ADVISORY UNTIL 6 AM...ALTHOUGH WINDS COULD VEER/DIMINISH EARLIER. SEAS WILL TOP OUT IN THE 2-4 FT RANGE ON NEARSHORE WATERS AND AS HIGH AS 5-6 FT BEYOND 20 NM. EXPECT ANOTHER VIGOROUS SEA BREEZE SUNDAY AFTERNOON/EARLY EVENING. WINDS WILL ONCE AGAIN APPROACH SCA THRESHOLDS...AND ADDITIONAL ADVISORIES MAY BE REQUIRED AT A LATER TIME. THE MARINE ZONES WILL REMAIN IN A TYPICAL SUMMER PATTERN ON THE WESTERN PERIPHERY OF ATLANTIC HIGH PRESSURE THROUGH THE EXTENDED PERIOD. SOUTHWEST WINDS WILL SURGE INTO THE 15 TO 20 KT RANGE SUNDAY NIGHT. THE PRESSURE GRADIENT WILL THEN RELAX EARLY IN THE WEEK. EXPECT THE GRADIENT TO TIGHTEN AGAIN BY LATE WEDNESDAY/EARLY THURSDAY...AS A FRONT APPROACHES FROM THE NORTHWEST AND UPPER LEVEL TROUGHING RESUMES OVER THE FORECAST AREA. COULD SEE NOCTURNAL SURGES BACK UP TO 15 TO 20 KT LATE IN THE WEEK AS A RESULT. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...HEAT ADVISORY FROM 12 PM TO 7 PM EDT SUNDAY FOR GAZ118-119. SC...HEAT ADVISORY FROM 12 PM TO 7 PM EDT SUNDAY FOR SCZ043>045- 047>051. SEVERE THUNDERSTORM WATCH UNTIL 1 AM EDT SUNDAY FOR SCZ040- 042>045-049. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT SUNDAY FOR AMZ350-352-374. SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR AMZ330-354. && $$ ST/REB ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 628 PM CDT FRI AUG 1 2008 .DISCUSSION... 324 PM CDT FOR SHORT TERM...FOCUS IS ON THUNDERSTORM CHANCES THIS EVENING AS WEAK COLD FRONT CONTINUES TO SAG SOUTH ACROSS SOUTHERN PORTIONS OF FORECAST AREA IN RESPONSE TO SHORT WAVE DIGGING ACROSS NORTHERN LAKES AND AMPLIFICATION OF LARGER SCALE TROUGH OVER EASTERN NOAM. MID AFTERNOON ANALYSIS DEPICTS FRONTAL BOUNDARY ROUGHLY SOUTH SIDE OF CHICAGO TO NEAR PEORIA...WITH COMBINATION OF DIFFERENTIAL HEATING BOUNDARY FROM EARLIER STRATUS DECK AND LAKE BREEZE ACROSS SOUTHEAST SIDE OF CHICAGO METRO/NORTHWEST INDIANA. WARM/HUMID CONDITIONS IN WARM SECTOR OVER SOUTH/SOUTHEAST CWA WITH LOW/MID 70S DEW POINT TEMPS AND UPPER 80S AIR TEMPS. SPC/RUC MESOANALYSIS DEPICTS MLCAPES OF 3500 J/KG ACROSS THIS AREA AT 19Z...AND THUNDERSTORMS HAVE INITIATED ALONG BOUNDARY ACROSS LAKE/PORTER COUNTY IN NORTHWEST IN. LOW LEVEL CONVERGENCE WEAK...THOUGH GIVEN INSTABILITY AND SHORT WAVE NOTED IN VAPOR/PROFILER DATA MOVING INTO NORTHERN IL EXPECT WILL CONTINUE TO SEE POTENTIAL FOR SCT/ISOLATED STORMS ACROSS SOUTHEASTERN PARTS OF FORECAST ARE AS FRONT CONTINUES TO MOVE SOUTHEAST THROUGH EARLY THIS EVENING. FRONT SAGS SOUTH OF CWA AS SURFACE HIGH PRESSURE BUILDS ACROSS THE WESTERN LAKES LATER TONIGHT...WITH COOLER/LESS HUMID AND CLEARING CONDITIONS. NICE QUIET WEATHER ACROSS THE AREA SATURDAY AS UPPER TROUGH MOVES TO THE EAST AND SURFACE HIGH PRESSURE RIDGE BUILDS ACROSS THE AREA. LOW LEVEL MODEL TEMP FORECASTS INDICATE MAX TEMPS TO RANGE FROM AROUND 80 NEAR THE LAKE WITH NORTHEAST WINDS...TO MID 80S IN INTERIOR PARTS OF FORECAST AREA. UPPER RIDGE THEN BUILDS ACROSS UPPER MIDWEST SATURDAY NIGHT THROUGH MONDAY...WITH SURFACE RIDGE MOVING OFF TO THE EAST. LOW LEVEL RETURN FLOW OF WARM/MOIST AIR DEVELOPS WEST OF MISSISSIPPI RIVER SATURDAY NIGHT...WITH GUIDANCE CONTINUING TO BE IN GOOD AGREEMENT IN DEVELOPING ELEVATED CONVECTION ON NOSE OF 35 KNOT 850 HPA JET EARLY SUNDAY MORNING. JET AXIS AND ELEVATED THERMAL GRADIENT SUGGESTS BEST POTENTIAL FOR THUNDERSTORMS INTO THE UPPER MISSISSIPPI VALLEY BY 12Z SUNDAY...SOUTHEAST MN/SOUTHWEST MN...WITH 850-300 MB THICKNESS FIELD AND CORFIDI VECTORS INDICATING INDIVIDUAL CONVECTIVE ELEMENTS SHOULD HAVE A SOUTH/SOUTHEAST PROPAGATION TOWARD NORTHWEST IL. WRF FORECAST SOUNDINGS INDICATE ONLY MARGINAL ELEVATED INSTABILITY FARTHER TO THE EAST WITH DRY LOW LEVELS IN PLACE ACROSS MOST OF CWA SUNDAY MORNING...THOUGH MODEST ISENTROPIC ASCENT ACROSS FRONTAL ZONE SUPPORTS CHANCE POPS ACROSS MAINLY NORTHWEST COUNTIES OF CWA INTO THE DAY SUNDAY. SURFACE WARM FRONT STRETCHES NORTH/SOUTH ALONG MS VLY WITH BEST LOW LEVEL WAA PUSH INTO WESTERN WI SUNDAY...SETTING UP PERHAPS BETTER CHANCE OF ELEVATED CONVECTION POTENTIAL SUNDAY NIGHT WITH NOCTURNAL STRENGTHENING OF LOW LEVEL JET AGAIN ACROSS MAINLY NORTHERN COUNTIES. HAVE ELECTED TO HAVE CHANCE POPS AFTER MIDNIGHT ACROSS ENTIRE CWA...THOUGH WILL SHADE HIGHEST POPS NORTH/LOWEST SOUTH. TEMPS FOR SUNDAY THROUGH TUESDAY PERIOD WILL BE CLOUD/PRECIP DEPENDANT...THOUGH STILL APPEARS SUNDAY WILL SEE WARMEST TEMPS WEST NEAR WARM FRONT...UPPER 80S BASED ON LOW LEVEL THERMAL PROGS...AND STILL A SOUTHEAST COMPONENT TO SURFACE WINDS WILL FAVOR COOLER TEMPS IN LOW-MID 80S NEAR LAKE IN NORTHEAST IL. WARMEST AIR SURGES INTO THE AREA SUNDAY NIGHT THROUGH MONDAY AS UPPER RIDGE LEANS INTO THE NORTHERN GREAT LAKES. SHORT WAVE DIGGING INTO THE NORTHERN PLAINS WILL KEEP POTENTIAL FOR THUNDER FROM NORTHERN PLAINS TO NORTHERN LAKES...WITH WEAK SURFACE LOW TRACKING ALONG LOW LEVEL FRONT/TROUGH TO OUR NORTH. FORECAST THERMAL FIELD CONTINUES TO INDICATE POTENTIAL FOR MID/UPPER 90S FOR AFTERNOON MAXES MONDAY...WITH DEW POINT TEMPS RETURNING TO THE LOW/MID 70S. THIS WOULD RESULT IN HEAT INDEX VALUES INTO THE 100-110 RANGE ACROSS THE FORECAST AREA MONDAY AFTERNOON AND THUS MAY NEED TO GO WITH HEAT WATCH AS EVENT DRAWS NEARER. FOR NOW WILL CONTINUE TO HIGHLIGHT IN HWO. OF COURSE IMPORTANT TO KEEP IN MIND THAT CLOUDS...CONVECTIVE OUTFLOW FROM NORTH OR RING OF FIRE CONVECTION OCCURRING A LITTLE FARTHER SOUTH MAY ULTIMATELY MODULATE MAX TEMPS THUS CONFIDENCE IN REACHING THESE HEAT CRITERIA NOT SUPER HIGH...BUT CERTAINLY THE POTENTIAL FOR THE WARMEST/MOST HUMID WEATHER OF THE YEAR EXISTS MONDAY CWA WIDE. GUIDANCE CONTINUES TO BRING SHORT WAVE ACROSS NORTHERN LAKES TUESDAY WITH FRONT SAGGING SOUTH ACROSS FORECAST AREA. THIS INCREASES THUNDERSTORM POTENTIAL ACROSS THE AREA AND SHOULD LIMIT OPPRESSIVE HEAT/HUMIDITY TO SOUTHERN PARTS OF FORECAST AREA TUESDAY AFTERNOON. SOUTHERN COUNTIES HOWEVER COULD SEE A SECOND DAY OF MID/UPPER 90S WITH HIGH HUMIDITIES. MODEL TRENDS THEN CONTINUE TO AMPLIFY UPPER TROUGH ACROSS NORTHERN/NORTHEAST CONUS WEDNESDAY THROUGH FRIDAY...WITH COOLER AND LESS HUMID CONDITIONS RETURNING. WEAK HIGH PRESSURE BUILDS ACROSS MID MS/LOWER OH VALLEY DURING THIS PERIOD...THOUGH SERIES OF EMBEDDED SHORT WAVE TROUGHS INDICATED ROTATING THROUGH LARGER SCALE TROUGH. CONFIDENCE ON TIMING/PRECIP THREAT WITH THESE VERY LOW AT THIS GREAT DISTANCE SO HAVE CHOSEN TO MAINTAIN DRY/COOLER CONDITIONS FOR END OF FORECAST PERIOD. RATZER && .AVIATION... 627 PM CDT 0000 UTC TAFS...SCATTERED SHOWERS AND STORMS WILL BE DIMINISHING ACROSS THE REGION INTO THE EVENING AS A COLD FRONT PUSHES THROUGH AND HIGH PRESSURE SETTLES IN FROM MINNESOTA INTO WISCONSIN INTO SATURDAY. THE LAKE BREEZE MADE IT OUT TO ORD/MDW AND HAS PRETTY MUCH WAVERED ALONG THE TWO STATIONS WITH ORD BEING PREDOMINANTLY NW AND MDW BEING MORE EASTERLY. WINDS SHOULD GO LIGHT AND VARIABLE OVERNIGHT AS THE RIDGE MOVES IN. WITH CLEAR SKIES OVERNIGHT AND LIGHT WINDS...COULD SEE SOME BR AT RFD/DPA TOWARD DAYBREAK BUT WITH DEW POINTS DROPPING AND FAIRLY DRY SOILS IT MAY BE HARD FOR THE FOG TO DEVELOP. WINDS WILL GO MORE NORTHEASTERLY SATURDAY WITH MAINLY CLEAR SKIES AND NOT MUCH IN THE WAY OF ANY CU OUT THERE. EXPECT VFR CONDITIONS THROUGHOUT. HALBACH && .MARINE... 108 PM CDT HIGH PRESSURE CURRENTLY OVER THE NORTHERN PLAINS WILL GRADUALLY MOVE E ACROSS THE UPPER MIDWEST TONIGHT...AND SETTLE OVER THE WESTERN GREAT LAKES REGION ON SATURDAY. THIS WILL KEEP WINDS LIGHT...GENERALLY FORCE 1 OR LESS...THRU WEEKEND. BY MONDAY MORNING THE HIGH WILL HAVE MOVED OVER THE UPPER OH VALLEY...WITH A LOW OVER THE CENTRAL PLAINS RESULTING A GRADUALLY INCREASING RETURN S AND SW FLOW. TSTMS WILL BE A CONCERN THIS AFTN...THEN AGAIN BY LATE SUNDAY INTO MONDAY. MERZLOCK && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 215 AM CDT FRI AUG 1 2008 .DISCUSSION... 350 PM CDT SHORT TERM...SEVERE MCS MOVING ACROSS NORTHEAST IL/NORTHWEST INDIANA THIS AFTERNOON AND WILL EXIT CWA NEXT COUPLE OF HOURS. REGIONAL RADAR MOSAIC DEPICTS MCV CIRCULATION ACROSS EASTERN WI...WITH RAIN COOLED/STABLE BOUNDARY LAYER EXTENDING BEHIND CURRENT ACTIVITY INTO NORTHEAST IOWA. THUS HAVE CANCELED WESTERN PORTIONS OF SEVERE THUNDERSTORM WATCH 782. CURRENT ACTIVITY EXPECTED TO CONTINUE TO PRESENT THREAT OF ISOLATED SEVERE CONVECTIVE WINDS...AS STORMS PROPAGATE SOUTHEAST ALONG/SOUTH OF OLD FRONTAL BOUNDARY IN REGION OF RUC INDICATED MLCAPE AXIS OF 1500-2000 J/KG. DEEP LAYER SHEAR DOES DECREASE FARTHER TO THE EAST SO SEVERE/ORGANIZATION EXPECTED TO REMAIN A LITTLE SPORADIC. ADDITIONAL COUNTIES TO BE CLEARED AS MAIN CONVECTIVE LINE... ALONG I55 AT 325 PM...MOVES OUT. WITH LOW LEVEL STABILIZING EFFECTS OF MCS AND SUBSIDENCE IN WAKE OF MCV EXPECT RELATIVELY DRY/QUITE PERIOD THIS EVENING. VARIOUS MODEL GUIDANCE HAS NOT BEEN HANDLING CONVECTIVE TRENDS TOO WELL... THOUGH APPEARS PRECIP POTENTIAL INCREASES AGAIN LATER TONIGHT WITH APPROACH OF MID LEVEL TROUGH AND WEAK SURFACE REFLECTION WHICH IS CURRENTLY ACROSS IA. SHOWER/THUNDERSTORM THREAT CONTINUES FRIDAY AS SURFACE LOW/FRONT SLIDE SOUTHEAST ACROSS FORECAST AREA. MID/UPPER LEVEL SPEED MAX TRANSLATES ACROSS WESTERN LAKES DURING THE DAY...WHICH COUPLED WITH WARM/MOIST BOUNDARY LAYER WILL PROVIDE SUFFICIENT SHEAR/CAPE FOR AT LEAST ISOLATED SEVERE THREAT ESPECIALLY SOUTHWEST HALF OF CWA. WITH FRONT SAGGING SOUTH OF AREA FRIDAY NIGHT...AND HIGH PRESSURE BUILDING FROM UPPER MISSISSIPPI VALLEY INTO WESTERN LAKES EXPECT DRY WEATHER...COOLER AND LESS HUMID CONDITIONS WHICH WILL CONTINUE INTO SATURDAY. FOCUS THEN SHIFTS TO HEAT WHICH LOOKS TO BUILD IN VERY LATE IN THE WEEKEND AS SURFACE HIGH MOVES OFF TO THE EAST AND UPPER RIDGE BUILDS INTO UPPER MIDWEST/WESTERN LAKES. BEST WARM ADVECTION REMAINS OFF TO THE WEST THROUGH MUCH OF SUNDAY SUGGESTING WEST/EAST GRADIENT IN TEMPS WITH READINGS WARMING INTO THE LOWER 90S ACROSS AREAS WEST OF I39...AND INTO THE UPPER 80S/NEAR 90 EAST. WITH SURFACE HIGH OVER THE CENTRAL LAKES...LIGHT GRADIENT WINDS AND SYNOPTIC SOUTHEAST FLOW SHOULD SUPPORT LAKE BREEZE/MODERATION ALONG ILLINOIS SHORE SUNDAY AFTERNOON. SOME POTENTIAL FOR ELEVATED CONVECTION WITH RETURNING WARM FRONT AND LOW LEVEL JET EARLY SUNDAY MORNING ACROSS MAINLY FAR WESTERN COUNTIES...THOUGH FORECAST SOUNDINGS DEPICT RATHER UNIMPRESSIVE MID LEVEL LAPSE RATES. WITH THIS IN MIND WILL INCLUDE JUST A SLIGHT CHANCE/20 POP FAR WEST AFTER MIDNIGHT SATURDAY NIGHT. APPEARS THE HOTTEST WEATHER OF THE SEASON SHOWS UP MONDAY AS RIDGE BUILDS OVERHEAD. GFS INDICATING 850 HPA TEMPS APPROACHING 26 DEG C BY MONDAY AFTERNOON...WITH GFS TEMP GUIDANCE INDICATING TEMPS IN MID/UPPER 90S ESPECIALLY OVER WEST/SOUTH CWA. SURFACE DEW POINT TEMPS IN LOW/MID 70S SUPPORT AFTERNOON HEAT INDEX VALUES IN 105-110 RANGE SO HEAT HEADLINES WILL NEED TO BE CONSIDERED IN THE NEXT COUPLE OF DAYS AS EVEN DRAWS CLOSER. SOME UNCERTAINTY EXISTS HOWEVER...WITH ECMWF NOT QUITE AS WARM WITH THERMAL RIDGE SUPPRESSED FARTHER SOUTH INTO CENTRAL IL AND WEAK SURFACE WAVE AND PRECIP ACROSS CWA. CANADIAN/GEM ALSO INDICATING SHORT WAVE FLATTENING RIDGE OVER CWA SIMILAR TO ECMWF. FOR NOW WILL MAINTAIN IDEA OF GOING FORECAST WITH MID 90S MONDAY...THOUGH WILL HAVE TO MONITOR. GUIDANCE THEN IN AGREEMENT FLATTENING OF UPPER RIDGE ACROSS GREAT LAKES AS MID LEVEL SHORT WAVE TROUGH CONTINUES TO PROPAGATE ACROSS UPPER MIDWEST/NORTHERN LAKES...AND IN SAGGING COLD FRONT SOUTH ACROSS FORECAST AREA ON TUESDAY. THIS SUGGESTS AT LEAST NORTHERN COUNTIES MAY NOT BE AS WARM TUESDAY...WHILE FAR SOUTHERN COUNTIES REMAIN IN HEAT. OF COURSE TEMPS WILL ULTIMATELY BE MODULATED BY CLOUDS/PRECIP POTENTIAL AS WELL AS THERMAL GRADIENT ASSOCIATED WITH SAGGING FRONT/LAKE BREEZE. FRONT CONTINUES TO DROP INTO CENTRAL IL WITH WEAK HIGH PRESSURE ACROSS NORTHERN LAKES AND COOLER TEMPS AND LOWER HUMIDITIES WEDNESDAY/THURSDAY. RATZER && .AVIATION... 140 AM CDT 06Z TAFORS...WEAK LOW PRESSURE HAD DRIFTED NORTHEASTWARD TO E CENTRAL WI OVER THE LAST FEW HOURS LIFTING THE BOUNDARY THAT LAID ACROSS FAR NORTHERN IL INTO NW IN THU EVENING NORTHWARD. SURFACE FLOW...WHAT LITTLE THERE IS...HAS BACKED TO SW OR S AND WITH 925MB WINDS PER VAD AND PROFILER DISPLAYS ALSO SHOWING BACKING TO W AND SW ACROSS NORTHERN IL. A FEW SHOWERS AND THUNDERSHOWERS HAVE BEEN PERSISTING IN EAST CENTRAL IA WHERE MAX INSTABILITY LOCATED WITH TEMPS IN THE MID 70S AND DEW POINTS IN THE LOWER 70S...AND WHERE WEAK CONVERGENCE OCCURRING AHEAD OF A NE- SW COOL FRONT ACROSS IA AS WELL AS UVV AS A SHORT WAVE TROF DROPS SE ACROSS IA. GIVEN WEAKNESS OF LOW LEVEL CONVERGENCE AS THE COOL FRONT DROPS INTO NORTHERN IL THIS MORNING AS WELL AS THE WEAK MID LEVEL UVV...FEEL THAT ANY SHOWERS OR THUNDERSHOWERS WILL BE ISOLATED OR WIDELY SCATTERED WITH LOW PROBABILITY OF OCCURRENCE AT A TERMINAL SO HAVE MAINTAINED IDEA OF VCTS. BY 18Z THE WEAK SURFACE LOW PROGGED TO BE IN S CENTRAL LOWER MI WITH THE COOL FRONT EXTENDING SW ACROSS N CENTRAL IN TO W CENTRAL IL WITH LOW LEVELS DRYING AS HI PRESSURE CURRENTLY OVER THE NORTHERN PLAINS BUILDS INTO THE UPPER MIDWEST. TRS && .MARINE... 215 AM CDT HIGH PRESSURE CURRENTLY OVER THE NORTHERN PLAINS WILL GRADUALLY MOVE E ACROSS THE UPPER MIDWEST AND BE OVER THE WESTERN GREAT LAKES SAT AND THE CENTRAL GREAT LAKES SUN KEEPING WINDS LIGHT ON LAKE MI. BY MON MORNING THE HIGH MOVES OVER THE UPPER OH VALLEY WITH A LOW IN THE CENTRAL PLAINS RESULTING A GRADUALLY INCREASING RETURN S AND SW FLOW. TRS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1201 AM CDT FRI AUG 1 2008 .DISCUSSION... ISSUED 830 PM CDT THU JUL 31 2008 RUC MODEL-BASED OBJECTIVE ANALYSES AND 00Z LINCOLN SOUNDING DATA SHOW A CAPPED AIRMASS IN PLACE OVER CENTRAL ILLINOIS THIS EVENING...AND THE CONVECTIVE INHIBITION WILL LIKELY INCREASE WITH SURFACE COOLING THIS EVENING. WATER VAPOR SATELLITE LOOPS INDICATE SHORTWAVE RIDGING AND ASSOCIATED SYNOPTIC SCALE SUBSIDENCE IN THE WAKE OF THE EARLIER NORTHERN ILLINOIS CONVECTIVE CLUSTER THAT IS NOW DECAYING OVER INDIANA. ALL OF THIS BODES POORLY FOR THE PROSPECTS OF NEW CONVECTIVE GENERATION OVER CENTRAL ILLINOIS THIS EVENING. FURTHER NORTHWEST...A COLD FRONT STRETCHING EAST/WEST ACROSS NORTHERN IOWA HAS SHOWN SOME RECENT ENHANCED CUMULUS DEVELOPMENT WHERE THE ENVIRONMENT IS MUCH MORE UNSTABLE AND THE CAP IS WEAKER. THUNDERSTORM DEVELOPMENT ALONG THIS FEATURE WILL BE POSSIBLE OVERNIGHT AS AN UPPER SHORTWAVE NOW OVER THE EASTERN DAKOTAS APPROACHES THE AREA. SHORT-RANGE MODELS DISAGREE ON HOW WELL THE RESULTANT MCS WOULD SURVIVE THIS FAR EAST WHERE THE AIRMASS IS MORE HOSTILE...OR INDEED IF ANY STORMS DEVELOP AT ALL. AT THIS TIME IT IS REASONABLE THAT SOME DEVELOPMENT SHOULD OCCUR LATER TONIGHT AND POSSIBLY MOVE ACROSS NORTH-CENTRAL ILLINOIS BEFORE DAWN. WILL THEREFORE KEEP THE CHANCE POPS IN THE NORTH GOING AS IS. NO FORECAST UPDATES ARE ANTICIPATED THIS EVENING. 04 && .AVIATION... ISSUED 1201 AM CDT FRI AUG 1 2008 CONVECTION BEGINNING TO DVLP OVER NERN IA ALONG PRE-FRONTAL TROF AHD OF A COLD FRONT THAT EXTENDS FROM CENT WI INTO NWRN IA. STORM MOTION VECTORS SUGGEST THAT THE STORMS WILL BRUSH PIA/BMI BEFORE DAWN... SO WILL ADD A TEMPO FOR THUNDER THERE 09Z-13Z. ALTHOUGH CHANCES ARE BELOW TEMPO CRITERIA FOR INCLUSION IN SPI/DEC/CMI...TSTMS MAY BE ADDED IF STORMS DEVELOP FURTHER SW OVER SERN IA. VSBYS ARE BEGINNING TO DROP THIS MORNING...SO WILL CONTINUE THE MENTION OF MVFR FOG THRU SUNRISE. COLD FRONT ON SCHEDULE TO REACH PIA AROUND 21Z FRI AND LIE ALG UIN-DNV CORRIDOR BY 00Z SAT. AIRMASS SHOULD BE MODERATELY UNSTABLE AHEAD OF THE FRONT WITH LESS INHIBITION THAN WAS OBSERVED THU AFTN. WILL THEREFORE PUT TEMPOS IN THE TAFS FOR TSTMS BEGINNING A COUPLE HOURS BEFORE FROPA...THEN HAVE JUST SCT STRATOCU BEHIND THE FRONT. 04 && .PREV DISCUSSION... ISSUED 254 PM CDT THU JUL 31 2008 ACTIVE NORTHWEST FLOW PATTERN WILL PERSIST ACROSS THE MIDWEST THROUGH SATURDAY...KEEPING THE THREAT FOR CONVECTION ALIVE...MAINLY ACROSS NORTHERN PARTS OF THE REGION. 19Z SURFACE ANALYSIS SHOWS WEAK LOW PRESSURE CENTERED OVER MINNESOTA...WITH NEARLY STATIONARY FRONTAL BOUNDARY EXTENDING E/SE INTO FAR NORTHERN ILLINOIS AND INDIANA. ALOFT...RIDGE IS BUILDING ACROSS THE DESERT SOUTHWEST AND CENTRAL PLAINS...WHILE W/NW FLOW REMAINS IN PLACE ACROSS THE MIDWEST AND OHIO VALLEY. SHORT TERM...TONIGHT THROUGH SUNDAY MCS THAT DEVELOPED LATE LAST NIGHT ACROSS THE DAKOTAS CONTINUES TO PROPAGATE E/SE ALONG STALLED FRONTAL BOUNDARY THIS AFTERNOON...AND IS CURRENTLY TRACKING ACROSS NORTHERN ILLINOIS TOWARD THE CHICAGO AREA. PRIMARY INSTABILITY AXIS HAS SET UP ALONG AND SOUTH OF THE BOUNDARY...WHERE LAPS CAPE VALUES IN EXCESS OF 4000J/KG ARE COMMON. THANKS TO EARLY MORNING FOG AND RESULTING SCT-BKN CLOUD COVER... ATMOSPHERE ACROSS CENTRAL ILLINOIS IS A LITTLE MORE STABLE. BASED ON INSTABILITY PARAMETERS AND LATEST RADAR/SATELLITE TRENDS...THINK STORMS WILL CONTINUE TO REMAIN JUST N/NE OF THE KILX CWA LATE THIS AFTERNOON INTO THE EVENING. WILL CONTINUE TO MONITOR OUTFLOW BOUNDARY LEFT BEHIND BY COMPLEX...AS POTENTIAL EXISTS FOR WIDELY SCATTERED CONVECTION ALONG AND NORTH OF THE I-74 CORRIDOR THIS EVENING. MODELS HAVE BEEN HANDLING CONVECTIVE EVOLUTION QUITE POORLY OVER THE PAST SEVERAL DAYS...SO ALL SOLUTIONS ARE SUSPECT FOR TONIGHT INTO FRIDAY. HOWEVER...WITH FRONTAL BOUNDARY REMAINING IN PLACE ACROSS FAR NORTHERN ILLINOIS AND W/NW FLOW PERSISTING ALOFT...THINK ADDITIONAL STORMS WILL FIRE ALONG THE BOUNDARY AND FOLLOW A SIMILAR PATH TO CURRENT CONVECTION. WILL THEREFORE KEEP FORECAST DRY ACROSS THE ENTIRE AREA DURING THE EVENING HOURS...BUT WILL INTRODUCE 30 POPS AFTER MIDNIGHT ALONG AND NORTH OF I-74. AS LOW PRESSURE TRACKS EASTWARD INTO THE GREAT LAKES ON FRIDAY...IT WILL BEGIN TO DRAG A WEAK COLD FRONT TOWARD THE AREA. THE ATMOSPHERE ACROSS CENTRAL ILLINOIS IS EXPECTED TO BECOME HIGHLY UNSTABLE FRIDAY AFTERNOON... WITH THE NAM-WRF SUGGESTING CAPE VALUES IN EXCESS OF 4000J/KG AND LIFTED INDICES BETWEEN -7 AND -9C. CONVERGENCE ALONG APPROACHING FRONTAL BOUNDARY APPEARS TO BE RATHER MODEST AND UPPER SUPPORT WILL REMAIN WELL TO THE NORTH ACROSS THE NORTHERN GREAT LAKES. DESPITE MITIGATING FACTORS...HIGH DEGREE OF INSTABILITY AND PRESENCE OF BOUNDARY WILL BE ENOUGH TO WARRANT POPS ACROSS MUCH OF THE AREA. WILL CARRY HIGHEST POPS ALONG AND NORTHEAST OF I-74 IN CLOSER PROXIMITY TO MESOSCALE BOUNDARIES LEFT BEHIND BY OVERNIGHT CONVECTION...TAPERING DOWN TO JUST SLIGHT CHANCE POPS ACROSS THE FAR S/SW CWA. WEAK COLD FRONT WILL SAG SOUTH OF THE AREA FRIDAY NIGHT...BRINGING AN END TO ANY PRECIP CHANCES AND INTRODUCING SLIGHTLY COOLER AND LESS HUMID CONDITIONS. WITH LIGHT N/NE SURFACE FLOW...HAVE LOWERED HIGH TEMPS FOR SATURDAY INTO THE UPPER 80S ACROSS THE BOARD. SLIGHT COOL-DOWN WILL BE SHORT-LIVED THOUGH...AS UPPER RIDGE BEGINS TO BUILD EASTWARD ON SUNDAY...RESULTING IN HIGH TEMPS CLIMBING INTO THE LOWER 90S. LONG TERM...MONDAY THROUGH THURSDAY THE HOTTEST WEATHER SO FAR THIS SUMMER IS STILL ON TAP FOR EARLY NEXT WEEK...AS UPPER RIDGE BECOMES CENTERED OVER THE MIDWEST. 850MB TEMPS CLIMB INTO THE 24 TO 26C RANGE ON MONDAY AND TUE...RESULTING IN HIGH TEMPS IN THE MIDDLE TO UPPER 90S. AT THE SAME TIME... DEWPOINTS AROUND 70 DEGREES WILL PRODUCE HEAT INDEX VALUES OVER 100 DEGREES...WHICH MEETS HEAT ADVISORY CRITERIA. MEDIUM RANGE MODELS STILL IN DISAGREEMENT AS TO WHEN NEXT FRONTAL BOUNDARY WILL APPROACH FROM THE NORTH. ECMWF IS BRINGING THE FRONT INTO ILLINOIS ON TUE... WHILE GFS KEEPS IT TO THE NORTH UNTIL WEDNESDAY. MODELS OFTEN BREAK DOWN UPPER PATTERNS TOO QUICKLY...SO PREFER THE SLOWER GFS HERE. WILL THEREFORE KEEP FORECAST DRY ON TUESDAY...BUT WILL INTRODUCE RAIN CHANCES WEDNESDAY AND WEDNESDAY NIGHT AS BOUNDARY SETTLES SOUTHWARD INTO THE AREA. THIS WILL BE FOLLOWED BY COOLER AND LESS HUMID WEATHER BY THE END OF NEXT WEEK. BARNES && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 950 AM CDT FRI AUG 1 2008 .UPDATE... PER MORNING DATA...FOG IS NOW CONFINED TO AROUND KDBQ. 0-30MB AGL RH FROM THE RUC APPEARS TO HANDLE THE LOW CLOUDS THE BEST. CLOUDS TO SLOWLY DISSIPATE THROUGH EARLY AFTERNOON WITH SUNNY SKIES EXPECTED. ...08... /PREVIOUS DISCUSSION/ .UPDATE... GRIDS WAS UPDATED EARLIER TO MENTION FOG AND LOWER POPS TO ONLY 20 PERCENT. WEAK COLD FRONT EXTENDED FROM NORTHWEST IL TO NORTHWEST MO AND WILL CONTINUE TO MAKE PROGRESS SOUTHEAST THIS MORNING. SEVERAL LOCATIONS HAVE DROPPED BELOW 1/4 MILE IN DENSE FOG BUT WAS NOT WIDESPREAD ENOUGH FOR AN ADVISORY. SPS WAS ISSUED INSTEAD. EXPECT IMPROVING CONDITIONS RAPIDLY BY 10 AM. .AVIATION... IFR CONDITIONS IN FG/BR WILL IMPROVE TO VFR CONDITIONS BY 15Z AND THEN VFR CONDITIONS THIS AFTERNOON AND TONIGHT AS HIGH PRESSURE BUILDS INTO THE REGION. ..HAASE.. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DODGE CITY KS 246 AM CDT SAT AUG 2 2008 .DISCUSSION... DAYS 1-2... FIRE WX IN THE WEST AND HEAT ADVISORY CONDITIONS IN THE EAST CONTINUE TO BE THE MAIN FORECAST CONCERNS. RIDGE CONTINUES TO BE FIRMLY IN PLACE OVER MUCH OF THE CENTRAL CONUS, WITH 500MB HEIGHTS ABOVE 5900 M AND VERY HOT TEMPERATURES. AT THE SFC, A LEE TROUGH EXTENDS FROM EASTERN MT DOWN INTO EASTERN CO/WESTERN KS. SOUTHERLY WINDS FROM THIS TROUGH HAVE HELPED TO BRING HIGHER DEWPOINTS INTO THE WEST, WITH READINGS NOW IN THE UPPER 50S AT EHA AND LBL. THE RICH MOISTURE CONTINUES OVER CENTRAL AND EASTERN KS, WITH DEWPOINTS CONTINUING IN THE 70S. MODELS ARE IN PRETTY GOOD AGREEMENT WITH NOT MUCH CHANGING IN THE OVERALL PATTERN FOR THE NEXT COUPLE OF DAYS. THE RIDGE AXIS WILL SHIFT A BIT FURTHER EASTWARD, AND THE SFC TROUGH WILL MOVE A BIT FURTHER INTO THE PLAINS TODAY AND TOMORROW. A BIG QUESTION WILL BE WHAT EXACTLY HAPPENS WITH THE DEWPOINTS. THE GFS AND NAM BOTH CONTINUE WITH FAIRLY MOIST READINGS IN THE WEST THROUGH THE EARLY MORNING, BUT BRING SOME DEWPOINTS IN THE LOWER 40S BACK OUT INTO OUR NORTHWESTERN COUNTIES BY LATE AFTERNOON. THE RUC SEEMS TO BE IN FAIRLY GOOD AGREEMENT WITH THIS, AND IT LOOKS LIKE RH VALUES WILL AGAIN GET DOWN AROUND 15 PERCENT. SOUTHERLY WINDS WILL CONTINUE TO BE FAIRLY BREEZY, WITH FREQUENT GUSTS ABOVE 20 MPH. WILL CONTINUE TO KEEP THE RED FLAG WARNING GOING THROUGH THIS AFTERNOON AND EARLY EVENING. THE SOUTHERLY WINDS WILL CONTINUE TO BRING MOISTURE UP INTO THE HIGH PLAIN ON SUNDAY, AND THIS TIME THE MODELS KEEP DEWPOINTS TO NEAR 50 ALL THE WAY TO THE CO BORDER. OF COURSE, MODEL DEWPOINTS ARE NOTORIOUSLY UNRELIABLE, BUT WILL ELECT TO KEEP AN EYE ON THINGS FOR NOW AND NOT GO WITH ANY WATCH. THE SOUTHERLY WINDS WILL KEEP MOISTURE IN THE EASTERN COUNTIES, WITH DEWPOINTS STAYING IN THE LOW 60S THROUGH TODAY AND INTO TOMORROW. TEMPERATURES WILL CONTINUE TO BE VERY HOT, AND THINK THAT EVEN HYS AND P28 SHOULD GET ABOVE THE CENTURY MARK TODAY. TOMORROW WILL BE EVEN HOTTER ACCORDING TO NAM AND GFS 850MB TEMPS. WITH THE FAIRLY HIGH DEWPOINTS, HEAT INDICIES SHOULD GET AROUND AND ABOVE 105 ACROSS THE EASTERN TIER. WILL CONTINUE WITH THE ADVISORY WE HAVE GOING TODAY, AND WILL EXTEND IT INTO SUNDAY AS THE HEAT CONTINUES. DAYS 3-7... THE MAIN FORECAST CHALLENGES FOR THIS EXTENDED PERIOD ARE THE TIMING OF THE COLD FRONT ON TUESDAY INTO WEDNESDAY AND CHANCES FOR RAIN. LOOK FOR THE WARM RIDGE TO FINALLY BREAKDOWN ON TUESDAY AND WEDNESDAY AS A NORTHERN BRANCH SHORTWAVE TROUGH PUSHES A COLD FRONT SOUTH INTO THE HIGH PLAINS. THE GFS HAS THE COLD FRONT THROUGH DODGE CITY BY AROUND 7 PM TUESDAY WHILE THE LATEST RUNS OF THE ECMWF HAVE IT A BIT FASTER AND THROUGH DODGE BY AROUND NOON. WILL HEDGE TOWARD FASTER ECMWF AND PUSH THE FRONT INTO THE NORTH CWA BY AFTERNOON. WILL ALSO ADD A SMALL POP NORTH AND THIS IS WHAT ICT HAD SUGGESTED. THE GFS THEN CONTINUES WITH RAIN FROM .01 TO .3 MAINLY NORTH AND EAST INTO THURSDAY SO WILL CONTINUE WITH SOME SMALL POPS TO COVER. TEMPS AHEAD OF THE FRONT ON MONDAY WILL BE AGAIN FROM 100 TO 105, THEN INTO THE LOW 90S WEDNESDAY AND THURSDAY, AND POSSIBLY COOLER INTO THE UPPER 80S BY FRIDAY AS THE ECMWF AND GFS CONTINUE WITH UPSLOPE FLOW. .AVIATION... EXPECT VFR CONDITIONS WITH SOUTHERLY SURFACE WINDS INCREASING TO 15 TO 25 KTS BY MID TO LATE MORNING. && .PRELIMINARY POINT TEMPS/POPS... DDC 105 72 104 72 / 0 0 0 0 GCK 105 71 104 69 / 0 0 0 0 EHA 104 69 101 69 / 0 0 0 0 LBL 105 71 104 69 / 0 0 0 0 HYS 103 72 105 73 / 0 0 0 0 P28 102 73 104 74 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY FROM NOON TODAY TO 8 PM CDT SUNDAY FOR KSZ031-046- 065-066-079>081-089-090. RED FLAG WARNING FROM 1 PM CDT /NOON MDT/ THIS AFTERNOON TO 9 PM CDT /8 PM MDT/ THIS EVENING FOR KSZ043-044-061>063-074>076- 084>086. && $$ FN26/06/06 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 1153 PM CDT THU JUL 31 2008 .AVIATION...06Z TAF ISSUANCE THE ONLY CONCERN OVERNIGHT IS THE FOG POTENTIAL AT THE CHANUTE TAF SITE. LATEST SURFACE ANALYSIS WAS STILL DEPICTING DEWPOINTS IN THE LOWER TO MID 70S IN THAT REGION WITH GOOD BOUNDARY LAYER DECOUPLING. HOWEVER...THE LATEST LAPS SOUNDINGS WERE INDICATING THAT THE MOISTURE DEPTH WAS FAIRLY SHALLOW. AS A RESULT...WE MAY SEE SOME PATCHY DENSE FOG DEVELOP IN SOUTHEAST KANSAS AFTER 09Z OR SO. AFTER 13Z...WE SHOULD SEE SOME SIGNIFICANT IMPROVEMENT WITH LIGHT WINDS AND VFR CONDITIONS EXPECTED DURING THE REMAINDER OF THE TAF FORECAST. COX && .PREV DISCUSSION... /ISSUED 932 PM CDT THU JUL 31 2008/ UPDATE... THE MAIN CONCERN OVERNIGHT WILL BE THE FOG POTENTIAL AGAIN MAINLY IN SOUTHEAST KANSAS. LATEST SURFACE ANALYSIS WAS SHOWING THE SURFACE DEWPOINTS IN THE LOWER TO MID 70S IN SOUTH CENTRAL AND SOUTHEAST KANSAS AT 02Z. THIS COMBINED WITH GOOD BOUNDARY LAYER DECOUPLING COULD CAUSE DENSE FOG DEVELOPMENT ACROSS SOUTHEAST KANSAS OVERNIGHT. THE ONLY MODEL THAT SEEMS TO HAVE A FAIRLY GOOD HANDLE ON THE SURFACE DEWPOINTS IS THE RUC WHICH SATURATES THE BOUNDARY LAYER ACROSS PORTIONS OF SOUTHEAST KANSAS OVERNIGHT. IN ADDITION...LAPS SOUNDINGS ARE SHOWING FAVORABLE DEWPOINT PROFILES. AT THIS TIME...WE PLAN ON BEEFING UP THE FOG POTENTIAL AND MENTION AREAS OF DENSE FOG. HOWEVER...WE MAY END UP GOING WITH A DENSE FOG ADVISORY AFTER FURTHER COLLABORATION. COX PREV DISCUSSION... /ISSUED 709 PM CDT THU JUL 31 2008/ AVIATION... 00Z TAFS...MAIN CONCERN TONIGHT IS FOR FOG POTENTIAL IN THE MORNING FOR SOUTH CENTRAL AND SOUTHEAST KANSAS TAF SITES. MVFR CONDITIONS ARE POSSIBLE AT KICT AND KHUT STARTING NEAR 1000Z AND BREAKING AFTER SUNRISE. IFR CONDITIONS ARE POSSIBLE AT KCNU BEGINNING NEAR 0900Z AND AGAIN BREAKING AFTER SUNRISE. CLEAR SKIES ARE EXPECTED FOR THE REMAINDER OF THE TAF PERIOD...HOWEVER...DURING THE AFTERNOON HOURS NEAR 2100Z FRIDAY KRSL AND KSLN TAF SITES WILL SEE LIGHT WINDS SHIFT FROM THE SOUTHWEST TO THE NORTHWEST AS THE SURFACE TROUGH EXTENDS INTO CENTRAL KANSAS BEFORE THE TROUGH WASHES OUT AND THE WINDS RETURN TO SOUTHEASTERLY. BILLINGS PREV DISCUSSION... /ISSUED 312 PM CDT THU JUL 31 2008/ DISCUSSION... THE MAIN FORECAST PROBLEM CENTERS ON THE UPCOMING HOT STRETCH OF WEATHER BEGINNING FRIDAY AND CONTINUING THROUGH AT LEAST EARLY NEXT WEEK. TONIGHT-TUESDAY: CLEAR SKIES...LIGHT WINDS...DECENT RADIATIONAL COOLING EXPECTED AGAIN TONIGHT. WE HAVE HAD A FULL AFTERNOON OF SUNSHINE/DRYING HOWEVER...AND ANTICIPATING MUCH LESS FOG POTENTIAL TONIGHT COMPARED TO LAST NIGHT. WILL KEEP A MENTION OF PATCHY FOG IN THE FLINT HILLS/SERN KS WHERE SOME OF THE HEAVIER RAINFALL OCCURRED IN THE PAST 36 TO 42 HOURS. THE UPPER HIGH CENTERED OVER THE 4 CORNERS REGION THIS AFTERNOON WILL SLIDE EASTWARD OVER THE CENTRAL PLAINS FOR THIS WEEKEND...WITH WARMING LOW-MID LEVEL TEMPERATURES IN THE ATMOSPHERE. ALTHOUGH THE UPPER RIDGE IS PROGGED TO FLATTEN OUT FROM THE SOUTHERN ROCKIES-SOUTHERN PLAINS-TENNESSEE VALLEY MONDAY THROUGH TUESDAY OF NEXT WEEK...LOW-MID LEVEL THICKNESSES WILL REMAIN VERY WARM ACROSS OUR AREA TO THE SOUTH OF A COLD FRONT OVER THE NORTHERN PLAINS. THEREFORE...CONFIDENCE IS HIGH THAT HOTTER CONDITIONS WILL DEVELOP FRIDAY AND THEN PERSIST THROUGH AT LEAST TUESDAY. SURFACE DEWPOINTS HAVE REMAINED IN THE UPPER 60S/LOWER 70S SO FAR THIS AFTERNOON AND GIVEN FAIRLY RECENT WIDESPREAD RAINFALL...WOULD ANTICIPATE IT MAY TAKE AT LEAST A COUPLE OF DAYS OF NEAR OR ABOVE 100 DEGREE HEAT TO MIX THEM DOWN LOWER. THEREFORE PLANNING A HEAT ADVISORY AREAWIDE FROM FRIDAY THROUGH MONDAY FOR THE TIME BEING AND CONTINUE TO EVALUATE THE POTENTIAL FOR FURTHER HEADLINES INTO EARLY NEXT WEEK WITH LATER MODEL RUNS. FRIDAY MAY BE MARGINAL IF WE DO NOT REACH ANTICIPATED HIGH TEMPERATURES DUE TO CONTINUED EVAPORATION FROM THE SOIL. WEDNESDAY-THURSDAY: CONFIDENCE IN TEMPERATURES LOWERS DURING THIS PERIOD GIVEN MODEL TRENDS TO KEEP BACKING OFF ON PUSHING A COLD FRONT SWD FROM THE NRN PLAINS INTO KANSAS. THE 12Z ECMWF NOW KEEPS THE FRONT NORTH OF OUR AREA THROUGH THURSDAY...WHEREAS THE 00Z RUN WAS BRINGING IT WELL INTO OUR FORECAST AREA. CONSENSUS WITH NCEP AND SURROUNDING OFFICES WAS TO LOWER HIGHS BACK INTO THE MID-UPPER 90S...HOWEVER THESE UPPER RIDGES CAN BE VERY TENACIOUS THIS TIME OF YEAR SO THIS REMAINS TO BE SEEN. JMC && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 71 99 73 100 / 0 0 0 0 HUTCHINSON 71 100 73 101 / 0 0 0 0 NEWTON 71 99 73 100 / 0 0 0 0 ELDORADO 71 98 73 99 / 0 0 0 0 WINFIELD-KWLD 71 98 74 100 / 0 0 0 0 RUSSELL 69 102 73 102 / 0 0 0 0 GREAT BEND 69 102 73 102 / 0 0 0 0 SALINA 71 100 74 101 / 0 0 0 0 MCPHERSON 71 100 74 101 / 0 0 0 0 COFFEYVILLE 71 96 73 98 / 0 10 0 0 CHANUTE 71 96 73 98 / 0 0 0 0 IOLA 71 95 73 98 / 0 0 0 10 PARSONS-KPPF 71 96 73 98 / 0 10 0 0 && .ICT WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY FROM 1 PM FRIDAY TO 8 PM CDT MONDAY FOR KSZ032-033- 047>053-067>072-082-083-091>096-098>100. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAKE CHARLES LA 112 PM CDT SAT AUG 2 2008 .UPDATE...ISSUED AN EXCESIVE HEAT WARNING FOR INTERIOR SOUTHEAST TEXAS AND ALL OF CENTRAL LOUISIANA WHICH IS VALID UNTIL 6 PM. && .DISCUSSION...HEAT INDEX VALUES ALREADY REACHING 109 IN ALEXANDRIA AND 108 IN JASPER WITH LITTLE IN THE WAY OF CONVECTION OVER THE NEXT FEW HOURS TO PRECLUDE HEAT INDICES FROM SOARING TO AROUND 112 DEGREES. UPDATED GRIDS AND ZONES. && .PREV DISCUSSION... /ISSUED 1013 AM CDT SAT AUG 2 2008/ UPDATE...MORNING SOUNDING AT LCH WAS MORE MOIST AND UNSTABLE THAN THE FCST SOUNDINGS. CONSIDERING THIS INITIALIZATIONN AND GFS THETA RIDGING AT H8, WILL GO AHEAD AND UP THE ANTE ON POPS TO 30 PERCENT FOR ALL EXCEPT EASTERN PORTIONS OF CEN LA WHERE RUC SHOWS GOOD NVA. CONVECTIVE TEMP AROUND 91 SHOULD BE REACHED BY 18Z (1PM). WILL MAKE THAT THE INITIAL TIME FOR THE SCATTERED POPS. LEFT TEMPS ALONE AND CONCUR ON THE MIXING. THAT SAID, WILL CONTINUE TO MONITOR THE AEX AREA FOR A HEAT INDICES APPROACHING 108 THIS AFTERNOON. PREV DISCUSSION... /ISSUED 535 AM CDT SAT AUG 2 2008/ DISCUSSION...CHALLENGING FORECAST ON TAP FOR THE NEXT SEVERAL DAYS RANGING FROM HEAT WAVE COURTESY OF MID/UPPER RIDGE BUILDING IN FROM THE NORTHWEST...POSSIBLE THUNDERSTORM COMPLEXES ROTATING AROUND IT...AND POTENTIAL TROPICAL TROUBLES SLIDING UNDERNEATH IT OVER THE COASTAL WATERS. FIRST...THE HEAT. UPPER RIDGE/INCREASING TEMPS WILL CONTINUE TO BUILD IN FROM THE NORTHWEST TODAY. SEVERAL LOCATIONS TOPPED OUT AT 100 OVER NORTHERN ZONES YESTERDAY...AND EXPECT AT LEAST ANOTHER 2 TO 3 DAYS OF READINGS IN THE 100 TO 105 RANGE FOR THE TEXAS LAKES AND CENTRAL LOUISIANA. READINGS FOR SOUTHEAST TEXAS/SOUTHERN LOUISIANA WILL TOP OUT IN THE MID TO UPPER 90S. FOLLOWED SAME GENERAL IDEA SPELLED OUT IN DISCUSSION YESTERDAY MORNING TO ARRIVE AT EXACT NUMBERS. STRONGLY CONSIDERED HOISTING A HEAT ADVISORY FOR PARTS OF THE AREA...BUT MY CONCERN IS THAT SFC DEWPOINTS WILL MIX OUT SUFFICIENTLY AS TO PRECLUDE CRITERIA BEING REACHED. DEWPOINTS WERE A GOOD 10 DEGREES BELOW GUIDANCE YESTERDAY AFTERNOON IN THE AREAS THAT REACHED THE CENTURY MARK...AND THIS IS VERY SIMILAR TO WHAT OCCURRED DURING THE LAST MINI HEAT WAVE ABOUT A WEEK AGO. WITH THIS IN MIND...WILL FORGO AN ADVISORY AT THIS TIME AND ADDRESS THE HEAT IN THE HWO. THUNDERSTORM POTENTIAL WILL MOSTLY BE TIED TO IMPULSES RIDING SOUTHWEST AROUND THE MID/UPPER RIDGE AND/OR CONVECTIVE OUTFLOW BOUNDARIES THAT MOVE INTO THE AREA LIKE YESTERDAY...MODELS SHOW A WIDE VARIETY OF SOLUTIONS IN THIS REGARD...THOUGH MOST ARE DECENT IN AGREEMENT THAT SUNDAY WOULD BE THE BEST OPPORTUNITY COURTESY ONE OF THESE IMPULSES. THOUGH DEEPEST MOISTURE WILL CONTINUE TO BE SHUNTED SOUTHWARD INTO THE NORTHERN GULF...WILL HAVE PWATS PROGGED AROUND 1.75 INCHES OR GREATER...WHICH IS MORE THAN ENOUGH. CARRIED SLIGHT POPS TODAY THROUGH MONDAY. CONCERNING THE TROPICS...THERE IS ALMOST UNANIMOUS SUPPORT NOW FOR SOMETHING DEVELOPING OFF THE TAIL END OF THE TROUGH OVER THE NORTH CENTRAL GULF...THEN MOVING WWD UNDERNEATH THE RIDGE. HOW MUCH...IF ANY...SFC REFLECTION THERE IS IS UP FOR DEBATE. THE NAM IS BY FAR THE MOST AGGRESSIVE...WITH A 40-50KT TS MOVING ALMOST DUE WEST AND INTO THE CENTRAL TEXAS COAST. THIS SOLUTION WAS DEEMED EXTREME AND THE NAM WAS IGNORED FOR GRID PURPOSES. THE CANADIAN GEM WAS ON THE OPPOSITE END OF THE SPECTRUM...SHOWING ALMOST NO SFC REFLECTION. THE ECMWF/UKMET/GFS WERE BETWEEN THE TWO. FOR THE PURPOSES OF THE FORECAST...FELT IT BEST TO USE A BLEND OF THE GFS AND ECMWF...WHICH YIELDED A CLOSED LOW WITH 20KT WINDS. THE UPPER LEVEL ENVIRONMENT OVER THE NORTHERN GULF WILL PROVIDE AT LEAST AN OPPORTUNITY FOR SOMETHING TO DEVELOP...BUT THE WINDOW WILL BE SPATIALLY AND TEMPORALLY SMALL AS AN UPPER LOW OVER WESTERN CUBA MOVES WEST INTO THE GULF. WILL OF COURSE CONTINUE TO MONITOR TRENDS. IN ANY EVENT...THE GREATEST IMPACTS ON THIS AREA WOULD BE FELT MONDAY AND TUESDAY...WITH ANOTHER MID/UPPER RIDGE BUILDING INTO THE AREA FOR THE END OF THE WEEK INTO NEXT WEEKEND. THIS ONE DOES NOT LOOK QUITE AS STRONG AND/OR HOT AS THE CURRENT ONE...SO TEMPS NEAR OR JUST ABOVE CLIMO LOOK FINE AS DO SLIGHT RAIN CHANCES. AVIATION...VFR EXPECTED TO PREVAIL. MARINE... LIGHT TO MODEST WEST TO SOUTHWEST FLOW WILL PREVAIL THROUGH MOST OF THE WEEKEND. LOW PRESSURE DEVELOPMENT OVER THE NORTH CENTRAL GULF WITH A SUBSEQUENT WESTWARD MOTION MAY RESULT IN HIGHER WINDS AND SEAS AS EARLY AS SUNDAY NIGHT...WHICH WOULD LAST THROUGH AT LEAST TUESDAY NIGHT. REFER TO DISCUSSION SECTION ABOVE FOR MORE DETAILS. MARINERS ARE ENCOURAGED TO CONTINUE TO MONITOR THE LATEST FORECASTS. && .PRELIMINARY POINT TEMPS/POPS... KLCH 95 77 97 77 94 / 30 10 20 20 20 KBPT 96 77 97 76 96 / 30 10 20 20 20 KAEX 101 79 97 77 98 / 20 20 20 20 10 KLFT 95 78 95 77 92 / 30 20 20 20 20 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...EXCESSIVE HEAT WARNING UNTIL 6 PM CDT THIS AFTERNOON FOR THE FOLLOWING ZONES: ALLEN...AVOYELLES...BEAUREGARD... EVANGELINE...RAPIDES...ST. LANDRY...VERNON. TX...EXCESSIVE HEAT WARNING UNTIL 6 PM CDT THIS AFTERNOON FOR THE FOLLOWING ZONES: HARDIN...JASPER...NEWTON...TYLER. GM...NONE. && $$ JS la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAKE CHARLES LA 1013 AM CDT SAT AUG 2 2008 .UPDATE...MORNING SOUNDING AT LCH WAS MORE MOIST AND UNSTABLE THAN THE FCST SOUNDINGS. CONSIDERING THIS INITIALIZATIONN AND GFS THETA RIDGING AT H8, WILL GO AHEAD AND UP THE ANTE ON POPS TO 30 PERCENT FOR ALL EXCEPT EASTERN PORTIONS OF CEN LA WHERE RUC SHOWS GOOD NVA. CONVECTIVE TEMP AROUND 91 SHOULD BE REACHED BY 18Z (1PM). WILL MAKE THAT THE INITIAL TIME FOR THE SCATTERED POPS. LEFT TEMPS ALONE AND CONCUR ON THE MIXING. THAT SAID, WILL CONTINUE TO MONITOR THE AEX AREA FOR A HEAT INDICES APPROACHING 108 THIS AFTERNOON. && .PREV DISCUSSION... /ISSUED 535 AM CDT SAT AUG 2 2008/ DISCUSSION...CHALLENGING FORECAST ON TAP FOR THE NEXT SEVERAL DAYS RANGING FROM HEAT WAVE COURTESY OF MID/UPPER RIDGE BUILDING IN FROM THE NORTHWEST...POSSIBLE THUNDERSTORM COMPLEXES ROTATING AROUND IT...AND POTENTIAL TROPICAL TROUBLES SLIDING UNDERNEATH IT OVER THE COASTAL WATERS. FIRST...THE HEAT. UPPER RIDGE/INCREASING TEMPS WILL CONTINUE TO BUILD IN FROM THE NORTHWEST TODAY. SEVERAL LOCATIONS TOPPED OUT AT 100 OVER NORTHERN ZONES YESTERDAY...AND EXPECT AT LEAST ANOTHER 2 TO 3 DAYS OF READINGS IN THE 100 TO 105 RANGE FOR THE TEXAS LAKES AND CENTRAL LOUISIANA. READINGS FOR SOUTHEAST TEXAS/SOUTHERN LOUISIANA WILL TOP OUT IN THE MID TO UPPER 90S. FOLLOWED SAME GENERAL IDEA SPELLED OUT IN DISCUSSION YESTERDAY MORNING TO ARRIVE AT EXACT NUMBERS. STRONGLY CONSIDERED HOISTING A HEAT ADVISORY FOR PARTS OF THE AREA...BUT MY CONCERN IS THAT SFC DEWPOINTS WILL MIX OUT SUFFICIENTLY AS TO PRECLUDE CRITERIA BEING REACHED. DEWPOINTS WERE A GOOD 10 DEGREES BELOW GUIDANCE YESTERDAY AFTERNOON IN THE AREAS THAT REACHED THE CENTURY MARK...AND THIS IS VERY SIMILAR TO WHAT OCCURRED DURING THE LAST MINI HEAT WAVE ABOUT A WEEK AGO. WITH THIS IN MIND...WILL FORGO AN ADVISORY AT THIS TIME AND ADDRESS THE HEAT IN THE HWO. THUNDERSTORM POTENTIAL WILL MOSTLY BE TIED TO IMPULSES RIDING SOUTHWEST AROUND THE MID/UPPER RIDGE AND/OR CONVECTIVE OUTFLOW BOUNDARIES THAT MOVE INTO THE AREA LIKE YESTERDAY...MODELS SHOW A WIDE VARIETY OF SOLUTIONS IN THIS REGARD...THOUGH MOST ARE DECENT IN AGREEMENT THAT SUNDAY WOULD BE THE BEST OPPORTUNITY COURTESY ONE OF THESE IMPULSES. THOUGH DEEPEST MOISTURE WILL CONTINUE TO BE SHUNTED SOUTHWARD INTO THE NORTHERN GULF...WILL HAVE PWATS PROGGED AROUND 1.75 INCHES OR GREATER...WHICH IS MORE THAN ENOUGH. CARRIED SLIGHT POPS TODAY THROUGH MONDAY. CONCERNING THE TROPICS...THERE IS ALMOST UNANIMOUS SUPPORT NOW FOR SOMETHING DEVELOPING OFF THE TAIL END OF THE TROUGH OVER THE NORTH CENTRAL GULF...THEN MOVING WWD UNDERNEATH THE RIDGE. HOW MUCH...IF ANY...SFC REFLECTION THERE IS IS UP FOR DEBATE. THE NAM IS BY FAR THE MOST AGGRESSIVE...WITH A 40-50KT TS MOVING ALMOST DUE WEST AND INTO THE CENTRAL TEXAS COAST. THIS SOLUTION WAS DEEMED EXTREME AND THE NAM WAS IGNORED FOR GRID PURPOSES. THE CANADIAN GEM WAS ON THE OPPOSITE END OF THE SPECTRUM...SHOWING ALMOST NO SFC REFLECTION. THE ECMWF/UKMET/GFS WERE BETWEEN THE TWO. FOR THE PURPOSES OF THE FORECAST...FELT IT BEST TO USE A BLEND OF THE GFS AND ECMWF...WHICH YIELDED A CLOSED LOW WITH 20KT WINDS. THE UPPER LEVEL ENVIRONMENT OVER THE NORTHERN GULF WILL PROVIDE AT LEAST AN OPPORTUNITY FOR SOMETHING TO DEVELOP...BUT THE WINDOW WILL BE SPATIALLY AND TEMPORALLY SMALL AS AN UPPER LOW OVER WESTERN CUBA MOVES WEST INTO THE GULF. WILL OF COURSE CONTINUE TO MONITOR TRENDS. IN ANY EVENT...THE GREATEST IMPACTS ON THIS AREA WOULD BE FELT MONDAY AND TUESDAY...WITH ANOTHER MID/UPPER RIDGE BUILDING INTO THE AREA FOR THE END OF THE WEEK INTO NEXT WEEKEND. THIS ONE DOES NOT LOOK QUITE AS STRONG AND/OR HOT AS THE CURRENT ONE...SO TEMPS NEAR OR JUST ABOVE CLIMO LOOK FINE AS DO SLIGHT RAIN CHANCES. AVIATION...VFR EXPECTED TO PREVAIL. MARINE... LIGHT TO MODEST WEST TO SOUTHWEST FLOW WILL PREVAIL THROUGH MOST OF THE WEEKEND. LOW PRESSURE DEVELOPMENT OVER THE NORTH CENTRAL GULF WITH A SUBSEQUENT WESTWARD MOTION MAY RESULT IN HIGHER WINDS AND SEAS AS EARLY AS SUNDAY NIGHT...WHICH WOULD LAST THROUGH AT LEAST TUESDAY NIGHT. REFER TO DISCUSSION SECTION ABOVE FOR MORE DETAILS. MARINERS ARE ENCOURAGED TO CONTINUE TO MONITOR THE LATEST FORECASTS. && .PRELIMINARY POINT TEMPS/POPS... KLCH 95 77 96 77 95 / 30 10 20 20 20 KBPT 96 76 97 76 97 / 30 10 20 20 20 KAEX 101 75 102 75 101 / 20 20 20 20 10 KLFT 95 78 96 78 95 / 30 20 20 20 20 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...NONE. && $$ JS la AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1057 AM EDT SAT AUG 2 2008 .SYNOPSIS... AN UPPER LEVEL DISTURBANCE WILL MVE ACROSS THE REGION THIS EVENING PUSHING A STRONG COLD FRONT THROUGH THE AREA LATER THIS AFTERNOON. SHOWERS AND THUNDERSTORMS ARE EXPECTED THIS AFTERNOON SOME POSSIBLY SEVERE WITH DAMAGING WINDS AND LARGE HAIL. HIGH PRESSURE WILL BUILD ACROSS THE AREA SUNDAY THROUGH MONDAY. ANOTHER FRONT WILL IMPACT THE REGION DURING THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... FIRST ROUND OF TSRA HAS EXITED THE AREA BUT ATMOSPHERE REMAINS VERY MOIST AND THE APPROACH OF A STRONG UPPER LVL DISTURBANCE LATER TODAY INDICATES THAT THERE WILL BE ANOTHER ROUND OF TSRA THIS AFTERNOON. MORNING CLOUDS ARE ALREADY THINING OUT MEANING THAT THERE WILL BE ENOUGH BREAKS FOR ADEQUATE HEATING/DESTABILIZATION FOR POTENTIAL SVR STORMS LATER THIS AFTERNOON. LATEST WRF MODELS AND RUC40 INDICATE THAT AREAS ALONG I-95 STAND THE BEST CHANCE FOR EXPERIENCING SVR WX. TIMING LOOKS TO BE BETWEEN 3PM AND 8PM. WOULD ANTICIPATE A SEVERE WEATHER WATCH LATER TODAY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/... THE FRONT WILL BE MOVING EAST OF THE FORECAST AREA BY EARLY EVENING...TAKING WITH IT MOST OF THE CONVECTION. WILL CONTINUE SLIGHT CHANCE TO CHANCE POPS ALONG AND EAST OF THE INTERSTATE 95 CORRIDOR THROUGH EARLY EVENING. NOT A LOT OF DRYING OR INCREASED WINDS BEHIND THIS FRONT...SO WILL HAVE TO LOOK OUT FOR FOG LATE SATURDAY NIGHT INTO EARLY SUNDAY MORNING. && .LONG TERM /SUNDAY THROUGH FRIDAY/... NO CHANGES MADE TO THE LONG TERM GRIDS DUE TO ACTIVE WEATHER OVERNIGHT. AN UPPER LOW WILL SLIDE EAST ACROSS NEW ENGLAND...BRINGING NOTABLE HEIGHT RISES ACROSS THE REGION EARLY NEXT WEEK. ZONAL FLOW TAKES OVER MID WEEK...AND A COLD FRONT IS EXPECTED ON WEDNESDAY. THIS WILL BE THE NEXT SIGNIFICANT CHANCE OF CONVECTION. && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/... SHOWERS AND THUNDERSTORMS WILL MOVE FROM WEST TO EAST ACROSS THE AREA EARLY THIS MORNING...THEN AGAIN EARLY THIS AFTERNOON. WILL TRY TO PIN DOWN TIMING WITH MORNING ACTIVITY AS STORMS PROGRESS EAST. SECOND ROUND OF STORMS WILL DEVELOP DURING THE LATE MORNING THROUGH NOON AND MOVE EAST. THE WASHINGTON AND BALTIMORE METRO TERMINALS HAVE THE BETTER CHANCES OF SEEING THE STRONGEST STORMS BETWEEN NOON AND 5PM. TIMING REMAINS UNCERTAIN...SO 12Z TAFS WILL MOST LIKELY MAINTAIN THE VICINITY THUNDERSTORMS. THE COLD FRONT WILL MOVE THROUGH THE REGION TODAY...AND EAST OF THE AREA THIS EVENING. RELATIVELY LIGHT WEST TO NORTHWEST WINDS ARE EXPECTED BEHIND THE FRONT TONIGHT. LOCATIONS THAT SEE RAIN TODAY AND CLEARING SKIES TONIGHT MAY SEE SOME FOG LATE TONIGHT INTO EARLY SUNDAY MORNING. NO SIGNIFICANT WEATHER IS EXPECTED SUNDAY THROUGH TUESDAY. THUNDERSTORMS ARE POSSIBLE AGAIN ON WEDNESDAY. && .MARINE... SOUTHERLY WINDS WILL CONTINUE AHEAD OF THE APPROACHING COLD FRONT. THIS WOULD LEAD TO CHANNELING UP THE BAY AND PORTIONS OF THE POTOMAC THIS MORNING AND AFTERNOON. HOWEVER...ONGOING CONVECTION COULD DISRUPT THAT FLOW. EITHER WAY...WIND GUSTS TO 20 KNOTS WILL BE POSSIBLE TODAY OVER THE WATERS. THEREFORE...WILL RAISE A SMALL CRAFT ADVISORY THROUGH EARLY EVENING. THUNDERSTORMS MOVING OVER THE WATERS TODAY WILL LIKELY PROMPT SPECIAL MARINE WARNINGS. STRONG SOUTHERLY FLOW WILL BE PRESENT TUESDAY NIGHT AND WEDNESDAY AS A COLD FRONT APPROACHES. THIS MAY REQUIRE A SMALL CRAFT ADVISORY TO BE POSTED IN SUBSEQUENT SHIFTS. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ UPDATE...ROSA PRODUCTS...SAR/SMZ md AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1046 AM EDT FRI AUG 1 2008 .SYNOPSIS... WEAK HIGH PRESSURE WILL REMAIN OVER THE REGION TODAY. ANOTHER COLD FRONT WILL APPROACH THE REGION OVERNIGHT INTO SATURDAY BRINGING THE CHANCE FOR SHOWERS AND THUNDERSTORMS. HIGH PRESSURE WILL BUILD OVER THE REGION FOR SUNDAY AND MONDAY...BUT THE NEXT FRONT WILL APPROACH THE AREA DURING THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... HOT DAY ON TAP WITH VERY WARM MID LEVEL TEMPS AROUND -6C AND H85 TEMPS WARMING UP TO 19C BY DAYS END. A LIGHT NW DOWNSLOPE SHOULD ALSO BOOST TEMPS INTO THE MID 90S. AS FOR CONVECTION...ONLY A BAY BREEZE IS EXPECTED TO SET UP BY DAYS END AND PERHAPS TRIGGER AN ISOLD TSRA ALG THE BAY BUT CVRG SHOULD BE LESS THAN 20%. BEST CHANCE OF ANYTHING POPPING UP IS OVR THE MTNS WHERE SOME CU ALREADY EVIDENT BUT EVEN HERE CVRG SHOULD ALSO BE SPARSE DUE TO LACK OF ANY TRIGGER. WILL HAVE TO WATCH FOR CONVECTION UPSTREAM OVER OH/IN TO SEE IF IT CAN MAKE IT THIS FAR EAST. OPTED TO ADD A SLIGHT CHANCE W OF THE BLUE RIDGE BASED ON 12Z RUC40 BUT CONFIDENCE IS NOT HIGH AT ALL THAT ANYTHING WILL DEVELOP. BETTER CHANCE FOR CONVECTION EXISTS LATE TONIGHT AS POTENT UPPER DISTURBANCE DROPS SWD AND AN MCS LIKELY TO ROLL THROUGH THE AREA. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/... A POTENT UPPER-LEVEL LOW WILL TRACK INTO NEW ENGLAND OVERNIGHT ALLOWING FOR THE NEXT COLD FRONT AND TROUGH AXIS TO APPROACH OUR CWA. GFS CONTINUES TO SHOW AN MCS DEVELOPING OVER THE CWA. THERE ARE FACTORS THAT LEAD TO THE POSSIBILITY OF CONVECTION. THE DYNAMICS ASSOCIATED WITH THE TROUGH AXIS AND COLD FRONT ALONG WITH A JET MAX WILL BE PUSHING INTO THE REGION OVERNIGHT. SREF GUIDANCE SHOWS MUCAPES AROUND 500-1000 J/KG. GIVEN THESE FACTORS...WILL CONTINUE TO LEAVE POPS IN THE FORECAST...BUT DID SLOW DOWN TIMING A BIT MAINLY TO THE OVERNIGHT. ALSO TWEAKED POPS DOWN FROM LIKELY TO CHANCE ACROSS MOST LOCATIONS EXCEPT THE NORTHWESTERN CWA. DESPITE THE FORCING AND INSTABILITY...STILL FEEL THAT THE GFS IS SUFFERING FROM CONVECTIVE FEEDBACK ISSUES AS PER COORDINATION WITH HPC. THEREFORE...TRENDED POPS CLOSER TO OTHER GUIDANCE. IF ENOUGH INSTABILITY DOES EXIST...THEN GUSTY WINDS AND HAIL COULD ACCOMPANY SOME OF THE STRONGER STORMS OVERNIGHT. MIN TEMPS WILL RANGE FROM THE LOWER 60S IN THE POTOMAC HIGHLANDS TO THE MID 70S IN DOWNTOWN WASHINGTON AND BALTIMORE. && .LONG TERM /SATURDAY THROUGH THURSDAY/... THE MODELS ARE STILL SHOWING AN MCS DROPPING SE IN THE FLOW LATE FRIDAY NIGHT INTO EARLY SATURDAY. OVER THE LAST FEW DAYS...THE MODELS HAVE DROPPED THE MCS FURTHER SOUTH AND HAVE SLOWED IT DOWN A BIT. SO...HAVE GONE AHEAD AND RAISED POPS FOR THE EARLY PART OF SATURDAY TO TRY AND BEST CAPTURE THIS FEATURE. LINGERING CLOUD COVER FROM THE MCS WILL LIKELY HELP STABILIZE THINGS QUITE A BIT IN THE NORTHWEST PORTION OF THE CWFA LATER ON SATURDAY. HOWEVER...A LOW PRESSURE TROUGH AND SHORTWAVE ENERGY ALOFT WILL COMBINE TO PRODUCE SOME ADDITIONAL CONVECTION IN THE AFTERNOON...ESPECIALLY IN THE EAST. HAVE GONE AHEAD AND ADJUSTED POPS UPWARDS A BIT IN THE AFTERNOON ALSO. THE REMAINDER OF THE LONG TERM FORECAST SHOULD BE MOSTLY QUIET. HIGH PRESSURE BUILDS OVER THE CWFA FOR SUNDAY THROUGH THE FIRST PART OF NEXT WEEK. SEVERAL PIECES OF SHORTWAVE ENERGY ARE NOTED IN THE NW FLOW ALOFT THROUGH THE EARLY PART OF THE WEEK. THESE IMPULSES COULD AID THE IN THE DEVELOPMENT OF ISOLATED SHRA/TSRA DEVELOPMENT DURING THIS TIME. HOWEVER...SINCE CHANCES ARE SO LOW AT THIS TIME...HAVE GONE THE OPTIMISTIC ROUTE AND LEFT THE FORECAST DRY FOR NOW. BY THE MID/LATE WEEK...A FRONT WILL SLOWLY DROP SOUTH OVER THE MID ATLANTIC. BY WEDNESDAY THE BOUNDARY SHOULD BE NEARING THE PA/MD BORDER...AND WILL CONTINUE TO DROP SLOWLY SOUTH ON THURSDAY. CHANCE POPS WERE ALREADY IN THE GRIDS...AND STILL LOOK GOOD. && .AVIATION /15Z FRIDAY THROUGH TUESDAY/... WEAK BOUNDARY MOVING THROUGH THE TERMINALS EARLY THIS MORNING...BUT LOW-LEVEL MOISTURE STILL REMAINS HIGH. THEREFORE...PATCHY BR IS EXPECTED ACROSS THE FAVORED TERMINALS...ESPECIALLY KCHO. FEEL THAT THERE WILL BE JUST ENOUGH OF A LIGHT GRADIENT TO PREVENT WIDESPREAD FOG FROM DEVELOPING. VFR CONDITIONS EXPECTED FOR LATER THIS MORNING THROUGH THIS EVENING. SCATTERED SHOWERS/T-STORMS ARE POSSIBLE OVERNIGHT AHEAD OF THE NEXT COLD FRONT. SUB VFR VSBYS/CIGS WILL BE LIKELY ON SATURDAY. IN THE MORNING...THE REMNANTS OF AN MCS WILL MOST LIKELY AFFECT THE NORTHERN TERMINALS. IN THE AFTERNOON...A SURFACE LOW PRESSURE TROUGH WILL COMBINE WITH COOLER TEMPERATURES ALOFT...AND SCATTERED SHOWERS AND THUNDERSTORMS ARE ANTICIPATED INTO THE EVENING. HIGH PRESSURE WILL BUILD OVER THE REGION SUNDAY THROUGH THE FIRST PART OF NEXT WEEK. && .MARINE... NO FLAGS EXPECTED THROUGH TONIGHT. WEST-NORTHWEST WINDS MAY TURN ONSHORE THIS AFTERNOON...ESPECIALLY ACROSS THE MIDDLE PORTION OF THE CHESAPEAKE BAY. SCATTERED SHOWERS/T-STORMS ARE POSSIBLE OVERNIGHT AS THE NEXT COLD FRONT APPROACHES. GUSTY WINDS CANNOT BE RULED OUT IN SOME OF THE STRONGER THUNDERSTORMS. SMALL CRAFT CONDITIONS ARE POSSIBLE ON SATURDAY BEHIND A LOW PRESSURE TROUGH. LOCAL MODEL RUNS AND BUFKIT SOUNDINGS SHOW THE POTENTIAL FOR WIND GUSTS AROUND 20 KT. SO HAVE RAISED A SMALL CRAFT ADVISORY FOR SATURDAY AFTERNOON AND EVENING. NO OTHER FLAGS ARE EXPECTED FOR THE REMAINDER OF THE LONG TERM PORTION OF THE FORECAST. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 PM SATURDAY TO MIDNIGHT EDT SATURDAY NIGHT FOR ANZ530>537. && $$ UPDATE...ROSA PRODUCTS...LASORSA/LISTEMAA md AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 745 PM EDT SAT AUG 2 2008 UPDATED AVIATION DISCUSSION FOR 00Z TAFS .SYNOPSIS... (ISSUED AT 425 PM EDT) WATER IMAGERY AND RUC SHOWING A CLOSED LOW OVER LAKE ONTARIO WITH A DEEP TROUGH AND AXIS STRETCHING SOUTH INTO THE MID ATLANTIC STATES...A RIDGING OVER MINNESOTA AND WESTERN ONTARIO... AND MORE TROUGHING OVER THE PACIFIC NORTHWEST AND WEST COAST. SURFACE ANALYSIS DEPICTS A RIDGE BLANKETING THE UPPER MISSISSIPPI RIVER VALLEY...UPPER GREAT LAKES AND NORTHERN ONTARIO. LOWS ARE OVER NORTHERN SASKATCHEWAN AND SOUTHWEST SOUTH DAKOTA WITH A COLD FRONT STRETCHED BETWEEN THEM. ALSO A WEAK FRONTAL SYSTEM STRETCHES FROM THE CENTRAL PLAINS ACROSS THE OHIO RIVER VALLEY TO THE MID ATLANTIC STATES. && .SHORT TERM... (TONIGHT AND SUN ISSUED AT 425 PM EDT) THE MID LEVEL RIDGE WILL SHIFT A LITTLE MORE INTO CENTRAL ONTARIO AS THE QUEBEC LOW STARTS TO DIG INTO THE NEW ENGLAND. THE SASKATCHEWAN LOW WILL SHIFT A LITTLE EAST ALSO. A WEAK SHORTWAVE RACING THROUGH THE RIDGE WILL SWEEP ACROSS THE FORECAST AREA LAKE TONIGHT. THE SURFACE RIDGE WILL CONTINUE TO BLANKET THE UPPER GREAT LAKES TONIGHT KEEPING DRY AIR IN PLACE WHICH WILL LIMIT CLOUDS AND AND PRECIPITATION POTENTIAL. SKIES SHOULD REMAIN MOSTLY CLEAR TONIGHT ALONG WITH LIGHT WINDS. THE MID LEVEL RIDGE OVER THE PLAINS WILL CONTINUE TO BUILD SHIFT EAST OVER THE FORECAST AREA ON SUNDAY. ANOTHER SHORTWAVE APPROACHING THE RIDGE WILL SLIDE INTO WESTERN U.P. SUNDAY AFTERNOON. THE RIDGE SURFACE RIDGE WILL ALSO SLIP INTO LOWER MICHIGAN AS THE SURFACE TROUGH MOVES INTO MINNESOTA. DRY AIR WITH THE RIDGE WILL KEEP PRECIPITATION OUT OF THE AREA ON SUNDAY. THE WINDS WILL VEER SOUTH ALLOWING LOW LEVEL MOISTURE TO BEGIN TO WORK INTO THE AREA BY LATE IN THE AFTERNOON...CAUSING AN INCREASE IN CLOUDS. THIS SOUTHERLY FLOW WILL ALSO CONTRIBUTE TO WARM AIR ADVECTION. THUS LOOKING FOR TEMPERATURES PUSHING INTO THE MID 80S. .LONG TERM... (SUNDAY NIGHT THRU SATURDAY) SUN NIGHT...THE WAA PATTERN IS EXPECTED TO BRING SHRA/TSRA TOWARD THE WRN GREAT LAKES. THE NAM AND GFS WERE IN AGREEMENT THAT A SHORTWAVE TROUGH...BAND OF 850 MB THETA-E ADVECTION AND ASSOCIATED 305K-310K ISENTROPIC LIFT WILL SPREAD ACROSS THE CWA. HOWEVER...AS IS OFTEN THE CASE...A MORE SIGNIFICANT MCS WOULD MORE LIKELY DEVELOP IN THE AREA OF GREATER INSTABILITY AND 925-850 MB CONV AND MOVE INTO WI (PER REGIONAL GEM AND NAM)...REDUCING MOISTURE INFLOW AND PCPN CHANCES OVER UPPER MI. SO...CURRENT CHANCE POPS STILL LOOK ON TRACK. 850 MB DEWPOINTS TO NEAR 15C AND MUCAPE AND MUCAPE VALUES AROUND 1000 J/KG AND EFFECTIVE SHEAR OF 30-35 KT COULD SUPPORT A FEW STRONGER ELEVATED STORMS...MAINLY OVER THE WEST HALF...WITH THREAT OF SMALL TO MARGINALLY SEVERE HAIL. MON...AFTER ANY MORNING SHRA/TSRA DIMINISH...A WEAK TROUGH/FRONT IS EXPECTED MOVE THROUGH UPPER MI...MAINTAINING A CHANCE FOR SHRA/TSRA. ALTHOUGH SBCAPE VALUES MAY CLIMB INTO THE 1000-1500 RANGE WITH SFC DEWPOINTS INTO THE MID 60S...ONLY CHANCE POPS WERE INCLUDED SINCE NAM/GFS FCST SOUNDINGS SUGGEST CAPPING MAY BE DIFFICULT TO OVERCOME. MON NIGHT INTO TUE...THE TRAILING MID LEVEL SHORTWAVE MOVES THROUGH THE AREA WITH ENOUGH LOW LEVEL MOISTURE IN PLACE TO KEEP SHRA/TSRA CHANCES GOING. WED-SAT...MODELS REMAINED IN FAIRLY GOOD AGREEMENT WITH THE PATTERN EVOLUTION TOWARD A TROUGH OVER SE CANADA. THE RESULTING NW FLOW THROUGH THE WRN GREAT LAKES...500 MB TEMPS TO AROUND -18C...AND A SERIES OF DIFFICULT TO TIME SHORTWAVES THROUGH THE AREA...SUPPORT SHRA/TSRA CHANCES...ESPECIALLY DURING PEAK HEATING. HOWEVER...GIVEN THE RELATIVELY DRY AIRMASS OVER THE AREA...ONLY LOWER END POPS WERE INCLUDED. THE OP GFS...ESPECIALLY THE 12Z RUN...WAS THE MOST AGGRESSIVE WITH THE SHORTWAVE TROUGH MOVING THROUGH THE LAKES THU INTO FRI. THE MORE CONSISTENT ECMWF WAS PREFERRED WHICH STILL CARVES OUT AN UNSEASONABLY DEEP TROUGH. TEMPS WILL REMAIN A BIT BLOW NORMAL AND MAY BE LOWERED FURTHER IF CONFIDENCE BECOMES HIGHER IN A PERIOD OF ENHANCED LOW/MID MOISTURE AND MAINLY CLOUDY SKIES. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... DRY LOW-LEVELS ASSOCIATED WITH HIGH PRES DRIFTING E ACROSS THE UPPER GREAT LAKES WILL RESULT IN VFR CONDITIONS PERSISTING THRU THIS FCST PERIOD AT KCMX/KSAW. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRESSURE OVER MN WILL MOVE OVER THE WESTERN GREAT LAKES TONIGHT AND THEN DRIFT TO THE EAST ON SUNDAY...KEEPING WINDS UNDER 20 KTS ACROSS LAKE SUPERIOR. SOUTHEASTERLY WINDS WILL INCREASE SUN NIGHT AS A LOW PRESSURE TROUGH APPROACHES FROM MN...BUT SPEEDS SHOULD STILL REMAIN AT OR BELOW 20 KTS. LIGHT WINDS ARE EXPECTED TO CONTINUE MON INTO MON NIGHT WITH THE TROUGH PASSAGE. WEST TO NORTHWEST WINDS MAY CREEP UP TO 20 KT ON TUE IN THE WAKE OF THE TROUGH. ANOTHER TROUGH IS EXPECTED TO DROP NORTH TO SOUTH ACROSS LAKE SUPERIOR ON WED. WEST WINDS OF UP TO 20 KT MAY OCCUR OVER NORTH CENTRAL LAKE SUPERIOR... WITH LIGHT WINDS ELSEWHERE. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM...DLG LONG TERM...JLB AVIATION...ROLFSON MARINE...DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 425 PM EDT SAT AUG 2 2008 .SYNOPSIS... WATER IMAGERY AND RUC SHOWING A CLOSED LOW OVER LAKE ONTARIO WITH A DEEP TROUGH AND AXIS STRETCHING SOUTH INTO THE MID ATLANTIC STATES...A RIDGING OVER MINNESOTA AND WESTERN ONTARIO... AND MORE TROUGHING OVER THE PACIFIC NORTHWEST AND WEST COAST. SURFACE ANALYSIS DEPICTS A RIDGE BLANKETING THE UPPER MISSISSIPPI RIVER VALLEY...UPPER GREAT LAKES AND NORTHERN ONTARIO. LOWS ARE OVER NORTHERN SASKATCHEWAN AND SOUTHWEST SOUTH DAKOTA WITH A COLD FRONT STRETCHED BETWEEN THEM. ALSO A WEAK FRONTAL SYSTEM STRETCHES FROM THE CENTRAL PLAINS ACROSS THE OHIO RIVER VALLEY TO THE MID ATLANTIC STATES. .SHORT TERM... THE MID LEVEL RIDGE WILL SHIFT A LITTLE MORE INTO CENTRAL ONTARIO AS THE QUEBEC LOW STARTS TO DIG INTO THE NEW ENGLAND. THE SASKATCHEWAN LOW WILL SHIFT A LITTLE EAST ALSO. A WEAK SHORTWAVE RACING THROUGH THE RIDGE WILL SWEEP ACROSS THE FORECAST AREA LAKE TONIGHT. THE SURFACE RIDGE WILL CONTINUE TO BLANKET THE UPPER GREAT LAKES TONIGHT KEEPING DRY AIR IN PLACE WHICH WILL LIMIT CLOUDS AND AND PRECIPITATION POTENTIAL. SKIES SHOULD REMAIN MOSTLY CLEAR TONIGHT ALONG WITH LIGHT WINDS. THE MID LEVEL RIDGE OVER THE PLAINS WILL CONTINUE TO BUILD SHIFT EAST OVER THE FORECAST AREA ON SUNDAY. ANOTHER SHORTWAVE APPROACHING THE RIDGE WILL SLIDE INTO WESTERN U.P. SUNDAY AFTERNOON. THE RIDGE SURFACE RIDGE WILL ALSO SLIP INTO LOWER MICHIGAN AS THE SURFACE TROUGH MOVES INTO MINNESOTA. DRY AIR WITH THE RIDGE WILL KEEP PRECIPITATION OUT OF THE AREA ON SUNDAY. THE WINDS WILL VEER SOUTH ALLOWING LOW LEVEL MOISTURE TO BEGIN TO WORK INTO THE AREA BY LATE IN THE AFTERNOON...CAUSING AN INCREASE IN CLOUDS. THIS SOUTHERLY FLOW WILL ALSO CONTRIBUTE TO WARM AIR ADVECTION. THUS LOOKING FOR TEMPERATURES PUSHING INTO THE MID 80S. && .LONG TERM...(SUNDAY NIGHT THRU SATURDAY) SUN NIGHT...THE WAA PATTERN IS EXPECTED TO BRING SHRA/TSRA TOWARD THE WRN GREAT LAKES. THE NAM AND GFS WERE IN AGREEMENT THAT A SHORTWAVE TROUGH...BAND OF 850 MB THETA-E ADVECTION AND ASSOCIATED 305K-310K ISENTROPIC LIFT WILL SPREAD ACROSS THE CWA. HOWEVER...AS IS OFTEN THE CASE...A MORE SIGNIFICANT MCS WOULD MORE LIKELY DEVELOP IN THE AREA OF GREATER INSTABILITY AND 925-850 MB CONV AND MOVE INTO WI (PER REGIONAL GEM AND NAM)...REDUCING MOISTURE INFLOW AND PCPN CHANCES OVER UPPER MI. SO...CURRENT CHANCE POPS STILL LOOK ON TRACK. 850 MB DEWPOINTS TO NEAR 15C AND MUCAPE AND MUCAPE VALUES AROUND 1000 J/KG AND EFFECTIVE SHEAR OF 30-35 KT COULD SUPPORT A FEW STRONGER ELEVATED STORMS...MAINLY OVER THE WEST HALF...WITH THREAT OF SMALL TO MARGINALLY SEVERE HAIL. MON...AFTER ANY MORNING SHRA/TSRA DIMINISH...A WEAK TROUGH/FRONT IS EXPECTED MOVE THROUGH UPPER MI...MAINTAINING A CHANCE FOR SHRA/TSRA. ALTHOUGH SBCAPE VALUES MAY CLIMB INTO THE 1000-1500 RANGE WITH SFC DEWPOINTS INTO THE MID 60S...ONLY CHANCE POPS WERE INCLUDED SINCE NAM/GFS FCST SOUNDINGS SUGGEST CAPPING MAY BE DIFFICULT TO OVERCOME. MON NIGHT INTO TUE...THE TRAILING MID LEVEL SHORTWAVE MOVES THROUGH THE AREA WITH ENOUGH LOW LEVEL MOISTURE IN PLACE TO KEEP SHRA/TSRA CHANCES GOING. WED-SAT...MODELS REMAINED IN FAIRLY GOOD AGREEMENT WITH THE PATTERN EVOLUTION TOWARD A TROUGH OVER SE CANADA. THE RESULTING NW FLOW THROUGH THE WRN GREAT LAKES...500 MB TEMPS TO AROUND -18C...AND A SERIES OF DIFFICULT TO TIME SHORTWAVES THROUGH THE AREA...SUPPORT SHRA/TSRA CHANCES...ESPECIALLY DURING PEAK HEATING. HOWEVER...GIVEN THE RELATIVELY DRY AIRMASS OVER THE AREA...ONLY LOWER END POPS WERE INCLUDED. THE OP GFS...ESPECIALLY THE 12Z RUN...WAS THE MOST AGGRESSIVE WITH THE SHORTWAVE TROUGH MOVING THROUGH THE LAKES THU INTO FRI. THE MORE CONSISTENT ECMWF WAS PREFERRED WHICH STILL CARVES OUT AN UNSEASONABLY DEEP TROUGH. TEMPS WILL REMAIN A BIT BLOW NORMAL AND MAY BE LOWERED FURTHER IF CONFIDENCE BECOMES HIGHER IN A PERIOD OF ENHANCED LOW/MID MOISTURE AND MAINLY CLOUDY SKIES. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... DRY CONDITION AND LIGHT WINDS UNDER THE HIGH PRESSURE REMAIN THROUGH TONIGHT...KEEPING VFR CONDITIONS TO BOTH TAF SITES. WINDS WILL BECOME LIGHT AND OUT OF THE SOUTH AFTER SUNRISE ON SUNDAY AS THE RIDGE MOVES A LITTLE EAST. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRESSURE OVER MN WILL MOVE OVER THE WESTERN GREAT LAKES TONIGHT AND THEN DRIFT TO THE EAST ON SUNDAY...KEEPING WINDS UNDER 20 KTS ACROSS LAKE SUPERIOR. SOUTHEASTERLY WINDS WILL INCREASE SUN NIGHT AS A LOW PRESSURE TROUGH APPROACHES FROM MN...BUT SPEEDS SHOULD STILL REMAIN AT OR BELOW 20 KTS. LIGHT WINDS ARE EXPECTED TO CONTINUE MON INTO MON NIGHT WITH THE TROUGH PASSAGE. WEST TO NORTHWEST WINDS MAY CREEP UP TO 20 KT ON TUE IN THE WAKE OF THE TROUGH. ANOTHER TROUGH IS EXPECTED TO DROP NORTH TO SOUTH ACROSS LAKE SUPERIOR ON WED. WEST WINDS OF UP TO 20 KT MAY OCCUR OVER NORTH CENTRAL LAKE SUPERIOR... WITH LIGHT WINDS ELSEWHERE. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM...DLG LONG TERM...JLB AVIATION...DLG MARINE...DLG mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 135 PM EDT SAT AUG 2 2008 .SYNOPSIS... WATER IMAGERY AND RUC SHOWING A CLOSED LOW OVER SOUTHERN QUEBEC WITH A DEEP TROUGH AND AXIS STRETCHING SOUTH INTO THE MID ATLANTIC STATES...A RIDGING OVER WESTERN MINNESOTA AND WESTERN ONTARIO... AND MORE TROUGHING OVER THE PACIFIC NW AND WEST COAST. SURFACE ANALYSIS DEPICTS A RIDGE BLANKETING THE UPPER MISSISSIPPI RIVER VALLEY...UPPER GREAT LAKES AND NORTHERN ONTARIO. LOW ARE OVER NORTHERN SASKATCHEWAN AND SOUTHWEST SOUTH DAKOTA WITH A COLD FRONT STRETCHED BETWEEN THEM. ALSO A WEAK FRONTAL SYSTEM STRETCHES FROM THE CENTRAL PLAINS ACROSS THE OHIO RIVER VALLEY TO THE MID ATLANTIC STATES. .SHORT TERM... THE MID LEVEL RIDGE WILL SHIFT A LITTLE MORE INTO WESTERN ONTARIO AS THE QUEBEC LOW STARTS TO DIG INTO THE NEW ENGLAND. THE SASKATCHEWAN LOW WILL SHIFT A LITTLE EAST ALSO. THE SURFACE RIDGE WILL CONTINUE TO BLANKET THE UPPER GREAT LAKES THIS AFTERNOON. A LITTLE LAKE BREEZE CONVERGENCE CAUSING A FEW CUMULUS CLOUDS TO DEVELOP THIS MORNING OVER THE NORTHERN U.P. DRY AIR ADVECTION SHOULD CAUSE THESE TO DISSIPATED BY EARLY AFTERNOON. OTHERWISE...SKIES SHOULD REMAIN MOSTLY SUNNY TODAY ALONG WITH LIGHT WINDS. TEMPERATURES WILL LIKELY PUSH UP TO AROUND 80 ACROSS THE AREA. LAKE BREEZES WILL KEEP TEMPERATURES A LITTLE COOLER ALONG THE LAKE. CURRENT FORECAST GRID AND ZFP LOOKS GOOD SO DO NOT PLAN TO MAKE ANY UPDATE AT THIS TIME. .LONG TERM... THE MID LEVEL RIDGE OVER THE PLAINS WILL CONTINUE TO BUILD EAST THROUGH SUNDAY WITH THE TROUGH IN THE PACIFIC NW TOPPING THE RIDGE AND STARTING TO FLATTEN IT ON SUNDAY WHILE THE QUEBEC TROUGH MOVES TO THE EAST COAST. SHORTWAVES MOVING ALONG THE PERIPHERY OF THE RIDGE AND SOUTHERN PART OF THE UPPER LEVEL TROUGH WILL AFFECT THE CWA SUN NIGHT THROUGH MON AS A STRONG 500 MB TROUGH FORMS ACROSS CENTRAL CANADA AND DIPS DOWN INTO THE NORTHERN PLAINS. NAM BRINGS IN SOME 850-500 MB Q-VECTOR CONVERGENCE INTO THE WESTERN CWA 00Z MON ALONG WITH SOME DEEPER MOISTURE AND STRONG Q-VECTOR CONVERGENCE SUN NIGHT AND THIS MOVES OUT LATE MON. NAM ALSO SHOWS SOME ISENTROPIC LIFT ON I300K-I315K SURFACES WITH SOME MOISTURE MOVING ACROSS THE CWA SUN NIGHT AND MON IN A NARROW BAND. THE MOISTURE LEAVES MON NIGHT ALONG WITH THE LIFT. GFS IS BRINGING IN SOME 850-500 MB Q-VECTOR CONVERGENCE SUN NIGHT ALONG WITH SOME MOISTURE WHICH LASTS INTO MON NIGHT. BASICALLY...WILL NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST. AGREE WITH PREVIOUS THINKING THAT PCPN WILL HOLD OFF UNTIL SUN EVENING AS LACK OF MOISTURE AND FORCING WILL PREVENT ANYTHING FROM MOVING IN AND WILL KEEP THINGS WEST OF HERE FOR NOW. GOING TEMPERATURES LOOKED GOOD AND DID NOT MAKE THAT MANY CHANGES EXCEPT FOR A FEW TWEAKS HERE AND THERE. FOR TODAY...LOW CLOUDS OVER THE EAST WILL MIX OUT AND PLENTY OF SUNSHINE WILL ALLOW TEMPERATURES TO MIX TO AT LEAST 850 MB AND MIX SOME DRY AIR DOWN TO THE SFC FOR LOWER DEW POINTS. NOT TOTALLY SURE ABOUT TUE WITH SLIGHT CHANCE POPS IN THERE...BUT ALL MODELS HAVE SOME UPPER LEVEL TROUGHING AND IF ANY SHORTWAVE ROTATES THROUGH THE TROUGH WITH ANY LITTLE BIT OF MOISTURE...CONCEIVABLE SOME ISOLATED CONVECTION CANNOT BE RULED OUT. NOT CONFIDENT IN THIS SCENARIO THOUGH AND RATHER THAN WAFFLE BACK AND FORTH...KEPT SLIGHT CHANCE POPS IN FOR CONSISTENCY SAKE. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... DRY CONDITION AND LIGHT WINDS UNDER THE HIGH PRESSURE REMAIN THROUGH TONIGHT...KEEPING VFR CONDITIONS TO BOTH TAF SITES. WINDS WILL BECOME LIGHT AND OUT OF THE SOUTH AFTER SUNRISE ON SUNDAY AS THE RIDGE MOVES A LITTLE EAST. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRESSURE OVER MN WILL MOVE OVER THE WESTERN GREAT LAKES TONIGHT AND THEN DRIFT TO THE EAST ON SUNDAY...KEEPING WINDS UNDER 20 KTS ACROSS LAKE SUPERIOR. SOUTHEASTERLY WINDS WILL INCREASE SUN NIGHT AS A LOW PRESSURE TROUGH APPROACHES FROM MN...BUT SPEEDS SHOULD STILL REMAIN AT OR BELOW 20 KTS. LIGHT WINDS ARE EXPECTED TO CONTINUE MON INTO MON NIGHT WITH THE TROUGH PASSAGE. WEST TO NORTHWEST WINDS MAY CREEP UP TO 20 KT ON TUE IN THE WAKE OF THE TROUGH. ANOTHER TROUGH IS EXPECTED TO DROP NORTH TO SOUTH ACROSS LAKE SUPERIOR ON WED. WEST WINDS OF UP TO 20 KT MAY OCCUR OVER NORTH CENTRAL LAKE SUPERIOR... WITH LIGHT WINDS ELSEWHERE. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM...DLG LONG TERM...GM AVIATION...DLG MARINE...AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 130 AM EDT SAT AUG 2 2008 UPDATED AVIATION DISCUSSION FOR 06Z TAF ISSUANCE .SYNOPSIS... WV IMAGERY AND RUC ANALYSIS INDICATED A TROUGH FROM HUDSON BAY INTO ONTARIO AND QUEBEC AND A RIDGE FROM THE SRN ROCKIES INTO SASK/MANITOBA. A WELL-DEFINED SHORTWAVE TROUGH WAS MOVING THROUGH NRN LAKE SUPERIOR. FORCING FOR LARGE SCALE ASCENT COMBINED WITH A WEAK SFC TROUGH...MLCAPE VALUES AROUND 1000 J/KG AND 0-6KM SHEAR TO 45 KT HAS TRIGGERED ISOLD SVR STORMS OVER CNTRL UPPER MI. ADDITIONAL SHRA/TSRA HAD ALSO DEVELOPED FROM CYQT TOWARD THE KEWEENAW...NEAR THE VORT CENTER. && .SHORT TERM... (TONIGHT AND SATURDAY) EXPECT THE REMAINING SHRA/TSRA TO EXIT THE SE CWA EARLY THIS EVENING AS THE SFC TROUGH SWINGS THROUGH AND SIGNIFICANTLY DRIER AIR MOVES IN. ISOLD SHRA/TSRA MAY ALSO BE POSSIBLE EARLY OVER N UPPER MI...CLOSEST TO THE VORT PATH. QVECTOR DIV AND SUBSIDENCE BEHIND THE SHORTWAVE WILL PREVAIL OVERNIGHT WITH CAA BRINGING COOLER AIR INTO THE AREA. THE NRLY FLOW AIDED BY LAKE MOISTURE SHOULD BRING INCREASING CLOUDS. HOWEVER...EXPECT ENOUGH DRY AIR TO FILTER IN SATURDAY MORNING FOR PARTIAL CLEARING AND HEATING FOR MAX READINGS TO AROUND 80 INLAND. BREEZE FROM LAKE SUPERIOR WILL KEEP TEMPS IN THE UPPER 60S AND LOWER 70S NEAR THE SHORE. .LONG TERM... (SAT NIGHT THRU FRI) SFC HIGH PRES RIDGE WILL VERY SLOWLY MOVE ACROSS UPPER MI SAT NIGHT...REACHING LWR MI SUN AFTN. RETURN FLOW ON THE BACK SIDE OF THE HIGH SAT NIGHT IS MINIMAL...SO ANOTHER TRANQUIL NIGHT IS EXPECTED. TEMPS SAT NIGHT WILL BE COOLEST OVER THE E HALF OF THE FCST AREA AS SFC HIGH DRIFTS ACROSS THAT AREA FOR MOST OF THE NIGHT. SINCE PRECIPITABLE WATER VALUES AREN`T MUCH BLO NORMAL FOR THIS TIME OF YEAR...PROBABLY DON`T NEED TO GO BLO GUIDANCE NUMBERS. SO...MIN TEMPS SHOULD RANGE FROM THE LOW TO MID 50S CNTRL/E TO THE MID/UPPER 50S WEST. WAA PATTERN DEVELOPS SUN...BUT IS MOST STRONGLY FOCUSED FROM MN TO SRN WI WHERE SFC WARM FRONT WILL BE SETTING UP. SO...CONVECTIVE DEVELOPMENT SHOULD REMAIN S AND W THE FCST AREA SUN. IN ADDITION... EXAMINATION OF NAM/GFS FCST SOUNDINGS MODIFIED FOR HIGH END OF POSSIBLE AFTN T/TD OF MID 80S/UPPER 50S SHOWS SIGNIFICANT CAPPING. THUS...ALL POPS FOR SUN AFTN WILL BE REMOVED. MON THRU FRI...MEDIUM RANGE MODEL AGREEMENT CONTINUES TO IMPROVE FOR THE OVERALL PATTERN NEXT WEEK. RIDGE THAT WILL HAVE EXPANDED E ACROSS THE SRN HALF OF THE U.S. BY MON WILL GET SUPPRESSED OVER THE E NEXT WEEK AS A FAIRLY SIGNIFICANT TROF FOR EARLY AUG AMPLIFIES INTO SE CANADA AND THE ERN CONUS. AS RESULT...ABOVE NORMAL TEMPS TO START THIS PERIOD WILL TREND DOWN TO BELOW NORMAL BY THU/FRI. TIMING OF COLD FRONT INITIATING THE COOL DOWN REMAINS FAIRLY WELL AGREED UPON AT THE MOMENT BY THE MODELS (UKMET/GFS/ECWMF)...PROBABLY CROSSING UPPER MI AT SOME POINT MON/MON NIGHT WHICH IS ON TRACK WITH WHAT WAS INDICATED BY THE MODELS YESTERDAY. UNTIL IT PASSES...THERE WILL BE A RISK OF SHRA/TSRA. WHILE SVR STORMS CAN`T BE RULED OUT... IT STILL LOOKS LIKE THE GREATER POTENTIAL OF SVR MAY STAY S OF THE FCST AREA AS THERE CONTINUES TO BE SOME INDICATION THAT A WARM FRONT/BOUNDARY WILL BE SET UP ACROSS MN/WI TO THE LOWER GREAT LAKES...AND THAT MAY FOCUS THE STRONGEST CONVECTION THERE. ALTHOUGH FROPA SHOULD OCCUR BY TUE MORNING...WILL LINGER POPS INTO TUE TO COVER POSSIBLE TIMING CHANGES WITH THE FRONT. THE PCPN FCST WED THRU FRI IS VERY UNCERTAIN. THE 00Z ECMWF/GFS ARE MOST AMPLIFIED WITH THE DEVELOPING TROF INTO THE GREAT LAKES THU/FRI...STRONGLY SUPPORTING MAINLY DIURNAL CONVECTION BOTH DAYS. IN FACT...SHOULD THE MORE AMPLIFIED SOLUTIONS PAN OUT...IT COULD BE A CHILLY/CLOUDY DAY FRI WITH OCCASIONAL -RA. SINCE NONE OF THE GFS ENSEMBLE MEMBERS ARE AS AMPLIFIED AS THE ECMWF/OP GFS...THAT SOLUTION APPEARS TO BE A VERY LOW PROBABILITY. IN ANY EVENT...GENERAL PATTERN OF DEEP CYCLONIC FLOW/CHILLY AIR ALOFT IS SUPPORTIVE OF SLIGHT CHC POPS THU AND FRI. IT`S POSSIBLE POPS MAY BE NEEDED FOR WED AS WELL...BUT SINCE TROF IS NOT SETTLING INTO THE AREA YET...WILL KEEP WED DRY FOR NOW. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... EXPECT DRIER AIR SHOWN ON THE 00Z RAOB FM INL AND EVIDENCED BY SFC DWPT IN THE UPR 40S OVER THE MN ARROWHEAD TO RESULT IN VFR CONDITIONS AT CMX THRU THIS FCST PD WITH HI PRES DOMINATING. BUT LINGERING LLVL MSTR FARTHER E AND WITH MORE FVRL NLY FLOW OFF LK SUP MAY RESULT IN A PD OF LO CLD/MVFR OR EVEN IFR CONDITIONS AT SAW EARLY THIS MRNG BEFORE DIURNAL HTG MIXES THE DRIER AIR TO THE SFC AFT SUNRISE. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRESSURE WILL BUILD INTO THE WESTERN GREAT LAKES SATURDAY AFTER A WEAK TROUGH MOVES THROUGH THE AREA TONIGHT WITH WINDS GETTING UP TO 20KT. THE MAIN WEATHER MAKER IS STILL EXPECTED TO BE FOR THE LAST HALF OF THE WEEKEND...AS LOW PRESSURE DEVELOPS ACROSS THE NORTHERN PLAINS SATURDAY...BRINGING A TROUGH TO WESTERN LAKE SUPERIOR BY EARLY MONDAY AFTERNOON...AND TO THE LOWER GREAT LAKES BY TUESDAY MORNING. HIGH PRESSURE WILL THEN FILTER INTO THE AREA FROM THE NORTHERN PLAINS && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM...JLB LONG TERM...ROLFSON AVIATION...KC MARINE...JLB mi AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MARQUETTE MI 730 PM EDT FRI AUG 1 2008 UPDATED FOR 00Z TAF ISSUANCE .SYNOPSIS... WV IMAGERY AND RUC ANALYSIS INDICATED A TROUGH FROM HUDSON BAY INTO ONTARIO AND QUEBEC AND A RIDGE FROM THE SRN ROCKIES INTO SASK/MANITOBA. A WELL-DEFINED SHORTWAVE TROUGH WAS MOVING THROUGH NRN LAKE SUPERIOR. FORCING FOR LARGE SCALE ASCENT COMBINED WITH A WEAK SFC TROUGH...MLCAPE VALUES AROUND 1000 J/KG AND 0-6KM SHEAR TO 45 KT HAS TRIGGERED ISOLD SVR STORMS OVER CNTRL UPPER MI. ADDITIONAL SHRA/TSRA HAD ALSO DEVELOPED FROM CYQT TOWARD THE KEWEENAW...NEAR THE VORT CENTER. && .SHORT TERM... (TONIGHT AND SATURDAY) EXPECT THE REMAINING SHRA/TSRA TO EXIT THE SE CWA EARLY THIS EVENING AS THE SFC TROUGH SWINGS THROUGH AND SIGNIFICANTLY DRIER AIR MOVES IN. ISOLD SHRA/TSRA MAY ALSO BE POSSIBLE EARLY OVER N UPPER MI...CLOSEST TO THE VORT PATH. QVECTOR DIV AND SUBSIDENCE BEHIND THE SHORTWAVE WILL PREVAIL OVERNIGHT WITH CAA BRINGING COOLER AIR INTO THE AREA. THE NRLY FLOW AIDED BY LAKE MOISTURE SHOULD BRING INCREASING CLOUDS. HOWEVER...EXPECT ENOUGH DRY AIR TO FILTER IN SATURDAY MORNING FOR PARTIAL CLEARING AND HEATING FOR MAX READINGS TO AROUND 80 INLAND. BREEZE FROM LAKE SUPERIOR WILL KEEP TEMPS IN THE UPPER 60S AND LOWER 70S NEAR THE SHORE. .LONG TERM... (SAT NIGHT THRU FRI) SFC HIGH PRES RIDGE WILL VERY SLOWLY MOVE ACROSS UPPER MI SAT NIGHT...REACHING LWR MI SUN AFTN. RETURN FLOW ON THE BACK SIDE OF THE HIGH SAT NIGHT IS MINIMAL...SO ANOTHER TRANQUIL NIGHT IS EXPECTED. TEMPS SAT NIGHT WILL BE COOLEST OVER THE E HALF OF THE FCST AREA AS SFC HIGH DRIFTS ACROSS THAT AREA FOR MOST OF THE NIGHT. SINCE PRECIPITABLE WATER VALUES AREN`T MUCH BLO NORMAL FOR THIS TIME OF YEAR...PROBABLY DON`T NEED TO GO BLO GUIDANCE NUMBERS. SO...MIN TEMPS SHOULD RANGE FROM THE LOW TO MID 50S CNTRL/E TO THE MID/UPPER 50S WEST. WAA PATTERN DEVELOPS SUN...BUT IS MOST STRONGLY FOCUSED FROM MN TO SRN WI WHERE SFC WARM FRONT WILL BE SETTING UP. SO...CONVECTIVE DEVELOPMENT SHOULD REMAIN S AND W THE FCST AREA SUN. IN ADDITION... EXAMINATION OF NAM/GFS FCST SOUNDINGS MODIFIED FOR HIGH END OF POSSIBLE AFTN T/TD OF MID 80S/UPPER 50S SHOWS SIGNIFICANT CAPPING. THUS...ALL POPS FOR SUN AFTN WILL BE REMOVED. MON THRU FRI...MEDIUM RANGE MODEL AGREEMENT CONTINUES TO IMPROVE FOR THE OVERALL PATTERN NEXT WEEK. RIDGE THAT WILL HAVE EXPANDED E ACROSS THE SRN HALF OF THE U.S. BY MON WILL GET SUPPRESSED OVER THE E NEXT WEEK AS A FAIRLY SIGNIFICANT TROF FOR EARLY AUG AMPLIFIES INTO SE CANADA AND THE ERN CONUS. AS RESULT...ABOVE NORMAL TEMPS TO START THIS PERIOD WILL TREND DOWN TO BELOW NORMAL BY THU/FRI. TIMING OF COLD FRONT INITIATING THE COOL DOWN REMAINS FAIRLY WELL AGREED UPON AT THE MOMENT BY THE MODELS (UKMET/GFS/ECWMF)...PROBABLY CROSSING UPPER MI AT SOME POINT MON/MON NIGHT WHICH IS ON TRACK WITH WHAT WAS INDICATED BY THE MODELS YESTERDAY. UNTIL IT PASSES...THERE WILL BE A RISK OF SHRA/TSRA. WHILE SVR STORMS CAN`T BE RULED OUT... IT STILL LOOKS LIKE THE GREATER POTENTIAL OF SVR MAY STAY S OF THE FCST AREA AS THERE CONTINUES TO BE SOME INDICATION THAT A WARM FRONT/BOUNDARY WILL BE SET UP ACROSS MN/WI TO THE LOWER GREAT LAKES...AND THAT MAY FOCUS THE STRONGEST CONVECTION THERE. ALTHOUGH FROPA SHOULD OCCUR BY TUE MORNING...WILL LINGER POPS INTO TUE TO COVER POSSIBLE TIMING CHANGES WITH THE FRONT. THE PCPN FCST WED THRU FRI IS VERY UNCERTAIN. THE 00Z ECMWF/GFS ARE MOST AMPLIFIED WITH THE DEVELOPING TROF INTO THE GREAT LAKES THU/FRI...STRONGLY SUPPORTING MAINLY DIURNAL CONVECTION BOTH DAYS. IN FACT...SHOULD THE MORE AMPLIFIED SOLUTIONS PAN OUT...IT COULD BE A CHILLY/CLOUDY DAY FRI WITH OCCASIONAL -RA. SINCE NONE OF THE GFS ENSEMBLE MEMBERS ARE AS AMPLIFIED AS THE ECMWF/OP GFS...THAT SOLUTION APPEARS TO BE A VERY LOW PROBABILITY. IN ANY EVENT...GENERAL PATTERN OF DEEP CYCLONIC FLOW/CHILLY AIR ALOFT IS SUPPORTIVE OF SLIGHT CHC POPS THU AND FRI. IT`S POSSIBLE POPS MAY BE NEEDED FOR WED AS WELL...BUT SINCE TROF IS NOT SETTLING INTO THE AREA YET...WILL KEEP WED DRY FOR NOW. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... EXPECT LINGERING SHRA TO END EARLY THIS EVNG AT SAW AS STRONG UPR DISTURBANCE SWINGS TO THE SE. DRIER AIR SHOWN ON THE 21Z TAMDAR SDNG FM INL AND EVIDENCED BY SFC DWPT OF 46 AT CKC WL RESULT IN VFR CONDITIONS AT CMX THRU THE NGT. BUT LINGERING LLVL MSTR FARTHER E AND WITH MORE FVRL NLY FLOW OFF LK SUP MAY RESULT IN A PD OF LO CLD/ MVFR OR EVEN IFR CONDITIONS AT SAW LATE TNGT BEFORE DIURNAL HTG MIXES THE DRIER AIR TO THE SFC AFT SUNRISE. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRESSURE WILL BUILD INTO THE WESTERN GREAT LAKES SATURDAY AFTER A WEAK TROUGH MOVES THROUGH THE AREA TONIGHT WITH WINDS GETTING UP TO 20KT. THE MAIN WEATHER MAKER IS STILL EXPECTED TO BE FOR THE LAST HALF OF THE WEEKEND...AS LOW PRESSURE DEVELOPS ACROSS THE NORTHERN PLAINS SATURDAY...BRINGING A TROUGH TO WESTERN LAKE SUPERIOR BY EARLY MONDAY AFTERNOON...AND TO THE LOWER GREAT LAKES BY TUESDAY MORNING. HIGH PRESSURE WILL THEN FILTER INTO THE AREA FROM THE NORTHERN PLAINS && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM...JLB LONG TERM...ROLFSON AVIATION...KC MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 710 PM EDT FRI AUG 1 2008 LATEST UPDATE...SHORT TERM AND AVIATION... .SYNOPSIS...(333 PM EDT FRI AUG 1 2008) MODIFIED MARITIME PACIFIC HIGH PRESSURE...WHICH AT 3 PM WAS LOCATED OVER THE NORTHERN PLAINS...WILL FOLLOW A WEAK SURFACE COLD FRONT INTO THE REGION TONIGHT. THERE IS A CHANCE A FEW SEVERE STORMS MAY DEVELOP HEAD OF THE FRONT AS IT MOVES THROUGH THE AREA EARLY THIS EVENING. THE PACIFIC ORIGIN AIRMASS WILL BRING SLIGHTLY COOLER AND DRIER AIR TO THE REGION SATURDAY. THE HIGH PRESSURE SYSTEM WILL BE EAST OF LOWER MICHIGAN SUNDAY ALLOWING THE SOUTHERLY FLOW ON THE WEST SIDE OF THE HIGH TO BRING WARMER AIR BACK INTO THE REGION. THE FRONT THAT CAME THROUGH THIS EVENING WILL COME BACK THROUGH AS A WARM FRONT MONDAY BRINGING THE HOTTEST TEMPERATURES OF THE SEASON TO MOST OF THE AREA. THE COLD FRONT WILL QUICKLY FOLLOW BY TUESDAY MORNING. THE FRONT WILL THEN STALL OVER SOUTHERN MICHIGAN AND THAT WILL RESULT IN PERIODS OF THUNDERSTORMS INTO WEDNESDAY. && .SHORT TERM...(710 PM EDT FRI AUG 1 2008) (TONIGHT) THE SHORTWAVE ON THE WATER VAPOR IS COMING ON SHORE OVER EASTERN LAKE MICHIGAN AS I WRITE THIS AT 7 PM. MOST OF THE STORMS HAVE WEAKENED AS THEY CROSS THE LAKE. ONE STORM EAST OF MKE SEEMS...BEING THE FARTHEST SOUTH AND HAVING THE BEST INFLOW IS ALSO NOW WEAKENING BUT REMAINS THE STRONGEST CELL. GIVEN THE 700 TO 500 MB QVEC CONVERGENCE FAVORS CONVECTION CROSSING THE CWA THIS EVENING AND THERE IS STILL AROUND 1000 J/KG OF MIXED LAYER CAPES JUST EAST OF US-131 AT 7 PM. THUS I BELIEVE IT IS STILL POSSIBLE THUNDERSTORMS ARE STILL POSSIBLE TILL THE SHORTWAVE IS EAST OF THE CWA AROUND MIDNIGHT. THE RISK OF SEVERE SEEMS LIMITED GIVEN SOUTHWEST LOWER MICHIGAN IS IN THE RIGHT EXIT REGION OF THE 300 MB JET CORE...WHICH ON THE RUC SHOWS HIGH LEVEL CONVERGENCE. ALSO THE HEAT OF THE DAY IS OVER NOW SO NOT TO MUCH HELP THERE EITHER. NOT SO SAY AN ISOLATED SEVERE STORM OUT OF THE QUESTION... BUT LIKELY NOT MORE THAN THAT. AFTER THE SHORTWAVE MOVES THROUGH SKIES WILL CLEAR STRONG MID LEVEL SUBSIDENCE FOLLOWS THE SHORTWAVE. && .LONG TERM...(1110 AM EDT FRI AUG 1 2008) (SATURDAY THROUGH FRIDAY) SEASONABLY MILD TEMPS ARE ANTICIPATED THIS WEEKEND. IT WILL TURN INCREASINGLY WARMER AND MORE HUMID SUNDAY NIGHT THROUGH EARLY NEXT WEEK ALONG WITH A THREAT FOR THUNDERSTORMS. WE WILL HAVE TO WATCH FOR POTENTIAL FOR SOME STRONG TO SEVERE STORMS IN THAT TIME FRAME DUE TO THE INCREASINGLY HUMID AND UNSTABLE AIR MASS. COOLER AND DRIER AIR WILL FILTER IN BEHIND THE COLD FRONT BEGINNING WEDNESDAY BUT ESPECIALLY FOR LATE NEXT WEEK. IN FACT BELOW NORMAL TEMPS ARE ANTICIPATED BY NEXT FRIDAY AS CANADIAN HIGH PRESSURE BUILDS IN. && .MARINE...(333 PM EDT FRI AUG 1 2008) ONCE THE THREAT OF THUNDERSTORMS IS OVER EARLY THIS EVENING...HIGH PRESSURE SHOULD CREATE A NEARLY IDEAL WEEKEND FOR BOATING AND GOING TO THE BEACH. && .AVIATION...(710 PM EDT FRI AUG 1 2008) MOSTLY HIGH AND MID CLOUDS THIS EVENING AHEAD OF THE COLD FRONT...ONCE THAT FRONT IS THROUGH SKIES SHOULD CLEAR. THERE IS A CHANCE OF THUNDERSTORMS ACROSS THE AREA THIS EVENING BUT GIVEN THE LIMITED COVERAGE OF THE CONVECTION ON RADAR NOW...I DO NOT PLAN ON PUTTING SHOWERS OR THUNDERSTORMS IN THE TAFS. MODEL SOUNDINGS SUGGEST SOME CU SATURDAY AFTERNOON. && .HYDROLOGY...(333 PM EDT FRI AUG 1 2008) RIVER AND STREAM LEVELS ACROSS THE HYDROLOGIC SERVICE AREA HAVE NOW DROPPED DOWN TO NEAR TO SLIGHTLY BELOW NORMAL WITH THE LACK OF WIDESPREAD RAIN OVER THE PAST COUPLE OF WEEKS. NOT MUCH THREAT FOR HEAVY RAIN WITH THE FRONT THIS EVENING AS ALMOST ALL OF THE STORMS WILL BE NORTH AND EAST OF THE GRR CWA. THE MORE POTENTIALLY SIGNIFICANT PERIOD FOR HYDRO WILL BE THE FIRST HALF OF THE WEEK AS A FRONT WILL BE IN THE REGION AND THERE COULD POTENTIALLY BE WAVES OF HEAVY RAIN PRODUCING STORMS. THIS SCENARIO IS STILL QUITE UNCERTAIN...BUT WILL NEED TO BE MONITORED. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ SYNOPSIS: WDM SHORT TERM: WDM LONG TERM: LAURENS MARINE: WDM AVIATION: WDM HYDROLOGY: WDM mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 438 PM EDT FRI AUG 1 2008 .SYNOPSIS... WV IMAGERY AND RUC ANALYSIS INDICATED A TROUGH FROM HUDSON BAY INTO ONTARIO AND QUEBEC AND A RIDGE FROM THE SRN ROCKIES INTO SASK/MANITOBA. A WELL-DEFINED SHORTWAVE TROUGH WAS MOVING THROUGH NRN LAKE SUPERIOR. FORCING FOR LARGE SCALE ASCENT COMBINED WITH A WEAK SFC TROUGH...MLCAPE VALUES AROUND 1000 J/KG AND 0-6KM SHEAR TO 45 KT HAS TRIGGERED ISOLD SVR STORMS OVER CNTRL UPPER MI. ADDITIONAL SHRA/TSRA HAD ALSO DEVELOPED FROM CYQT TOWARD THE KEWEENAW...NEAR THE VORT CENTER. && .SHORT TERM... (TONIGHT AND SATURDAY) EXPECT THE REMAINING SHRA/TSRA TO EXIT THE SE CWA EARLY THIS EVENING AS THE SFC TROUGH SWINGS THROUGH AND SIGNIFICANTLY DRIER AIR MOVES IN. ISOLD SHRA/TSRA MAY ALSO BE POSSIBLE EARLY OVER N UPPER MI...CLOSEST TO THE VORT PATH. QVECTOR DIV AND SUBSIDENCE BEHIND THE SHORTWAVE WILL PREVAIL OVERNIGHT WITH CAA BRINGING COOLER AIR INTO THE AREA. THE NRLY FLOW AIDED BY LAKE MOISTURE SHOULD BRING INCREASING CLOUDS. HOWEVER...EXPECT ENOUGH DRY AIR TO FILTER IN SATURDAY MORNING FOR PARTIAL CLEARING AND HEATING FOR MAX READINGS TO AROUND 80 INLAND. BREEZE FROM LAKE SUPERIOR WILL KEEP TEMPS IN THE UPPER 60S AND LOWER 70S NEAR THE SHORE. .LONG TERM... (SAT NIGHT THRU FRI) SFC HIGH PRES RIDGE WILL VERY SLOWLY MOVE ACROSS UPPER MI SAT NIGHT...REACHING LWR MI SUN AFTN. RETURN FLOW ON THE BACK SIDE OF THE HIGH SAT NIGHT IS MINIMAL...SO ANOTHER TRANQUIL NIGHT IS EXPECTED. TEMPS SAT NIGHT WILL BE COOLEST OVER THE E HALF OF THE FCST AREA AS SFC HIGH DRIFTS ACROSS THAT AREA FOR MOST OF THE NIGHT. SINCE PRECIPITABLE WATER VALUES AREN`T MUCH BLO NORMAL FOR THIS TIME OF YEAR...PROBABLY DON`T NEED TO GO BLO GUIDANCE NUMBERS. SO...MIN TEMPS SHOULD RANGE FROM THE LOW TO MID 50S CNTRL/E TO THE MID/UPPER 50S WEST. WAA PATTERN DEVELOPS SUN...BUT IS MOST STRONGLY FOCUSED FROM MN TO SRN WI WHERE SFC WARM FRONT WILL BE SETTING UP. SO...CONVECTIVE DEVELOPMENT SHOULD REMAIN S AND W THE FCST AREA SUN. IN ADDITION... EXAMINATION OF NAM/GFS FCST SOUNDINGS MODIFIED FOR HIGH END OF POSSIBLE AFTN T/TD OF MID 80S/UPPER 50S SHOWS SIGNIFICANT CAPPING. THUS...ALL POPS FOR SUN AFTN WILL BE REMOVED. MON THRU FRI...MEDIUM RANGE MODEL AGREEMENT CONTINUES TO IMPROVE FOR THE OVERALL PATTERN NEXT WEEK. RIDGE THAT WILL HAVE EXPANDED E ACROSS THE SRN HALF OF THE U.S. BY MON WILL GET SUPPRESSED OVER THE E NEXT WEEK AS A FAIRLY SIGNIFICANT TROF FOR EARLY AUG AMPLIFIES INTO SE CANADA AND THE ERN CONUS. AS RESULT...ABOVE NORMAL TEMPS TO START THIS PERIOD WILL TREND DOWN TO BELOW NORMAL BY THU/FRI. TIMING OF COLD FRONT INITIATING THE COOL DOWN REMAINS FAIRLY WELL AGREED UPON AT THE MOMENT BY THE MODELS (UKMET/GFS/ECWMF)...PROBABLY CROSSING UPPER MI AT SOME POINT MON/MON NIGHT WHICH IS ON TRACK WITH WHAT WAS INDICATED BY THE MODELS YESTERDAY. UNTIL IT PASSES...THERE WILL BE A RISK OF SHRA/TSRA. WHILE SVR STORMS CAN`T BE RULED OUT... IT STILL LOOKS LIKE THE GREATER POTENTIAL OF SVR MAY STAY S OF THE FCST AREA AS THERE CONTINUES TO BE SOME INDICATION THAT A WARM FRONT/BOUNDARY WILL BE SET UP ACROSS MN/WI TO THE LOWER GREAT LAKES...AND THAT MAY FOCUS THE STRONGEST CONVECTION THERE. ALTHOUGH FROPA SHOULD OCCUR BY TUE MORNING...WILL LINGER POPS INTO TUE TO COVER POSSIBLE TIMING CHANGES WITH THE FRONT. THE PCPN FCST WED THRU FRI IS VERY UNCERTAIN. THE 00Z ECMWF/GFS ARE MOST AMPLIFIED WITH THE DEVELOPING TROF INTO THE GREAT LAKES THU/FRI...STRONGLY SUPPORTING MAINLY DIURNAL CONVECTION BOTH DAYS. IN FACT...SHOULD THE MORE AMPLIFIED SOLUTIONS PAN OUT...IT COULD BE A CHILLY/CLOUDY DAY FRI WITH OCCASIONAL -RA. SINCE NONE OF THE GFS ENSEMBLE MEMBERS ARE AS AMPLIFIED AS THE ECMWF/OP GFS...THAT SOLUTION APPEARS TO BE A VERY LOW PROBABILITY. IN ANY EVENT...GENERAL PATTERN OF DEEP CYCLONIC FLOW/CHILLY AIR ALOFT IS SUPPORTIVE OF SLIGHT CHC POPS THU AND FRI. IT`S POSSIBLE POPS MAY BE NEEDED FOR WED AS WELL...BUT SINCE TROF IS NOT SETTLING INTO THE AREA YET...WILL KEEP WED DRY FOR NOW. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... A SHORTWAVE TROUGH BRUSHING LAKE SUPERIOR COMBINED WITH UNSTABLE AIR OVER CNTRL UPPER MI WILL RESULT IN SCT/ISOLD TSRA...WHICH COULD AFFECT KSAW THROUGH MID AFTERNOON. STABLE FLOW OFF OF LAKE SUPERIOR WILL REDUCE CHANCES FOR ANY TSRA. COOLER MORE STABLE AIR WILL MOVE IN THIS EVENING WITH MAINLY VFR CONDITIONS. THERE IS THE POTENTIAL FOR LOWER MVFR OR IFR CIGS AT KSAW WITH UPSLOPE MOIST NRLY LOW LEVEL FLOW DEVELOPING. ANY LOWER CLOUDS ARE EXPECTED TO LIFT BY MID MORNING. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRESSURE WILL BUILD INTO THE WESTERN GREAT LAKES SATURDAY AFTER A WEAK TROUGH MOVES THROUGH THE AREA TONIGHT WITH WINDS GETTING UP TO 20KT. THE MAIN WEATHER MAKER IS STILL EXPECTED TO BE FOR THE LAST HALF OF THE WEEKEND...AS LOW PRESSURE DEVELOPS ACROSS THE NORTHERN PLAINS SATURDAY...BRINGING A TROUGH TO WESTERN LAKE SUPERIOR BY EARLY MONDAY AFTERNOON...AND TO THE LOWER GREAT LAKES BY TUESDAY MORNING. HIGH PRESSURE WILL THEN FILTER INTO THE AREA FROM THE NORTHERN PLAINS && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM...JLB LONG TERM...ROLFSON AVIATION...JLB MARINE...JLB mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 215 PM EDT FRI AUG 1 2008 UPDATED FOR 18Z AVIATION DISCUSSION .UPDATE... WV IMAGERY AND RUC ANALYSIS INDICATED A SHORTWAVE TROUGH MOVING THROUGH UPPER MI THAT HELPED SUPPORT DIMINISHING/WEAKENING AREA OF SHRA/TSRA OVER THE CNTRL CWA. ANOTHER SHRTWV WAS LOCATED JUST NW OF CYQT. THE BEST FORCING WITH THE UPSTREAM SHRTWV SHOULD REMAIN NORTH AND EAST OF LAKE SUPERIOR. HOWEVER...SFC HEATING WITH TEMPS TO NEAR 80F AND DEWPOINTS IN THE UPPER 50S...WITH MLCAPE VALUES TO AROUND 1000 J/KG ...EXPECT ISOLD SHRA/TSRA TO REDEVELOP...ESPECIALLY ALONG LAKE BREEZE BOUNDARIES IN THE ERN CWA. 0-6 KM SHEAR VALUES AROUND 40 KT COULD ALSO SUPPORT ISOLD STRONG STORMS WITH SMALL HAIL AND 40 MPH WINDS. ONLY MINOR ADJUSTMENTS WERE MADE TO GOING GRIDS/FCST. .DISCUSSION... UPPER AIR PATTERN CONSISTS OF A 500 MB RIDGE ACROSS THE WESTERN HALF OF THE U.S. WITH TROUGHING OVER THE EAST AND PACIFIC NW. THERE IS A SHORTWAVE ACROSS THE ARROWHEAD OF MN AND THIS HAS BEEN KICKING OFF SOME SHOWERS AND THUNDERSTORMS THIS EVENING OVER MN. THIS SHORTWAVE WILL CONTINUE TO DIG SE AND AFFECT THE CWA TODAY WITH UPPER LEVEL RIDGING THEN BUILDING IN TONIGHT AND SAT BEFORE THE NAM SHOWS A SHORTWAVE TOPPING AND MOVING THROUGH THE RIDGE SAT NIGHT. NAM SHOWS SOME WEAK 850-500 MB Q-VECTOR CONVERGENCE ALONG WITH MARGINAL DEEP MOISTURE TODAY MOVING ACROSS THE AREA. GFS IS THE SAME WAY. WILL CUT POPS BACK TO SLIGHT CHANCE THIS MORNING. AS THIS AFTERNOON COMES...POSSIBILITY OF SOME LAKE BREEZES WILL HELP TO KICK OFF SOME THUNDERSTORMS AND WILL GO CHANCE POPS IN THE LAKE BREEZE PRONE CONVERGENCE AREAS ACROSS THE CENTRAL CWA. OVERALL...DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST TEMPERATURE WISE EXCEPT WARMED THEM UP A BIT SUN NIGHT IN DOWNSLOPE AREAS NEAR THE LAKESHORE TO 70 DEGREES OR SO. REMOVED POPS FROM SAT NIGHT AS GFS...NAM AND ECMWF ARE DRY AND THAT CONTINUED TO LOOK GOOD WITH 500 MB RIDGING IN CONTROL. WOULD NOT BE SURPRISED TO SEE SUNDAY DRY AS WELL...BUT CONFIDENCE IS LOW ENOUGH NOT TO REMOVE SLIGHT CHANCE POPS ACROSS THE WEST HALF FOR NOW. TEMPERATURES WILL CONTINUE TO BE SLIGHTLY ABOVE NORMAL. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... A SHORTWAVE TROUGH BRUSHING LAKE SUPERIOR COMBINED WITH UNSTABLE AIR OVER CNTRL UPPER MI WILL RESULT IN SCT/ISOLD TSRA...WHICH COULD AFFECT KSAW THROUGH MID AFTERNOON. STABLE FLOW OFF OF LAKE SUPERIOR WILL REDUCE CHANCES FOR ANY TSRA. COOLER MORE STABLE AIR WILL MOVE IN THIS EVENING WITH MAINLY VFR CONDITIONS. THERE IS THE POTENTIAL FOR LOWER MVFR OR IFR CIGS AT KSAW WITH UPSLOPE MOIST NRLY LOW LEVEL FLOW DEVELOPING. ANY LOWER CLOUDS ARE EXPECTED TO LIFT BY MID MORNING. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRESSURE WILL GENERALLY BE THE RULE...MINUS A BRIEF DISRUPTION BY A TROUGH CROSSING OVER THE AREA TONIGHT WITH WINDS GETTING UP TO 20KT. THE MAIN WEATHER MAKER IS STILL EXPECTED TO BE FOR THE LAST HALF OF THE WEEKEND...AS LOW PRESSURE DEVELOPS ACROSS THE NORTHERN PLAINS SATURDAY...BRINGING A TROUGH TO WESTERN LAKE SUPERIOR BY EARLY MONDAY AFTERNOON...AND TO THE LOWER GREAT LAKES BY TUESDAY MORNING. HIGH PRESSURE WILL THEN FILTER INTO THE AREA FROM THE NORTHERN PLAINS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...JLB DISCUSSION...GM AVIATION...KF MARINE...KF mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 126 PM EDT FRI AUG 1 2008 .AVIATION...UPPER DISTURBANCE MOVING THRU THE NORTHERN LAKES REGION WILL KICK OFF SCT SHOWERS AND STORMS IN PARTS OF NORTHERN LOWER MI THIS AFTERNOON AND EARLY EVENING. TVC HAS THE BEST CHANCE OF BEING IMPACTED...AS STORMS ARE ALREADY FIRING IN EASTERN WI...AND WILL BE MOVING ACROSS THE LAKE. SKIES WILL PARTIALLY CLEAR THIS EVENING. BUT NORTHERLY WINDS OVERNIGHT WILL BRING IN MOISTURE AT VERY LOW LEVELS...AND EXPECT AN IFR TO PERHAPS LIFR STRATUS DECK BY DAWN. THIS DECK WILL GRADUALLY MIX OUT TO AN MVFR CUMULUS DECK BY MIDDAY. JZ && .UPDATE...ISSUED 1039 AM FRI AUG 1... SOMEWHAT COMPLICATED WX TO DEAL WITH OVER THE NEXT 12 HOURS. THE MOST OBVIOUS SURFACE FEATURE IS AN AREA OF HIGH PRESSURE IN THE EASTERN DAKOTAS. THIS IS PROVIDING A BACKGROUND WEAK NORTHWESTERLY LOW LEVEL FLOW. A COUPLE OF SURFACE TROFS/WEAK COLD FRONTS ARE SEEN...ONE FROM THE THUMB TO FAR NORTHERN IL...AND A VERY SUBTLE ONE THAT APPEARS TO RUN FROM NORTHERN WI THRU THE STRAITS AND ON TO FAR NORTHERN LK HURON. ALOFT...A WELL-DEFINED SHORTWAVE DIGGING ACROSS SUPERIOR WAS SUPPORTING AREAS OF DEEP CONVECTION ALL NIGHT. HOWEVER...PRECIP HAS BEEN WEAKENING SINCE SUNRISE. SHOWERS AND A FEW STORMS WERE LOCATED IN S CENTRAL SUPERIOR...AND IN NE WI. PRECIP TRENDS AND SVR POTENTIAL ARE THE MAIN CONCERNS. TODAY...WITH COOLER AIR ARRIVING ABOVE 750MB TODAY THANKS TO THE INCOMING SHORTWAVE...WE WILL HAVE A CHANCE TO FIRE OFF SURFACE-BASED CONVECTION. A 78/61 SURFACE PARCEL PRODUCES ABOUT 900J/KG OF MLCAPE...THAT SHOULD BE ABOUT THE TOP-END FOR INSTABILITY. THE LOW LEVEL FLOW IS AND WILL REMAIN WEAK...RESULTING IN MINIMAL SHEAR IN THE LOW LEVELS...BUT ALSO ALLOWING LAKE BREEZES TO DEVELOP AND PROVIDE ADDITIONAL TRIGGER MECHANISMS. NO MAJOR CONCERNS FOR STRONG STORMS NEAR AND NORTH OF THE BRIDGE... WHERE MORNING STRATUS HAS HINDERED HEATING. TO THE SOUTH...THE COMBINATION OF STRONG MID-LEVEL FLOW (WNW 500MB WINDS OF 45KT) AND LOWERING FREEZING LEVELS (FROM 12.5K TO 11K FEET THIS AFTERNOON)... WILL ALLOW FOR SOME STRONGER STORMS PRODUCING BOTH BRIEF GUSTY WINDS AND SMALL HAIL. AN ISOLATED SVR STORM OR TWO STILL SEEMS REASONABLE AWAY FROM THE IMMEDIATE LAKE MI COAST. WILL ADJUST TIMING FOR PRECIP AND CLOUD COVER A BIT IN THE GRIDS... THOUGH THIS WILL NOT HAVE MUCH IMPACT IN THE TEXT PRODUCTS. TEMPS LOOK DECENT...WE ALREADY HAD EASTERN UPPER MI ON THE COOL SIDE AND THAT LOOKS REALLY GOOD NOW. HEATING IN THE SE ZONES HAD BEEN INHIBITED BY WARM ADVECTION MID DECK...BUT THAT IS MOVING OUT NOW AND THEY HAVE PLENTY OF TIME TO WARM UP TO NEAR 80. JZ && .PREV DISCUSSION... /ISSUED 404 AM EDT FRI AUG 1 2008/ 02Z SURFACE/RUC ANALYSIS...AND IR/WV/RADAR IMAGERY SHOW RELATIVELY ZONAL FLOW ACROSS THE NORTHERN TIER OF THE CONUS ATOP A BROAD AND ELONGATED SOUTHERN CONUS RIDGE. SEVERAL SHORTWAVES CAN BE SEEN WITHIN THIS ZONAL FLOW...ONE PASSING ACROSS IN/OH...A MYRIAD OF WAVES OVER SASKETCHEWON/MANITOBA/ONTARIO...AND A DEEPER WAVE JUST OFFSHORE OF THE PAC NORTHWEST. CLUSTERS OF THUNDERSTORMS CONTINUE AT THIS HOUR OVER SOUTHERN ONTARIO/ARROWHEAD OF MN WITHIN THE LEFT EXIT REGION OF A 80KT JET STREAK/700-500MB -DIVQ/AND H850 TROUGH AXIS EXTENDING ACROSS ONTARIO/LAKE SUPERIOR INTO QUEBEC. LOW STRATUS CONTINUES TO DRIFT SOUTH ALONG THIS TROUGH TOWARDS EASTERN UPPER AIDED BY RAPID BL COOLING...WHILE OTHER STRATO-CU/CU OVER THE HIGHER TERRAIN OF UPPER MICHIGAN HAS BEEN DRIFTING ACROSS NORTHERN LAKE MICHIGAN TOWARDS NORTHERN LOWER WITH WHAT LOOKS LIKE A WEAK WARM FRONTAL SIGNATURE NE OF A SURFACE CIRCULATION OVER WISCONSIN. SOME SPOTTY SHOWERS HAVE BEEN NOTED WITHIN THIS CLOUD COVER HEADING TOWARDS THE LEELANAU PENINSULA. MAIN FORECAST CONCERNS TODAY CENTER ON NUISANT MORNING CLOUD COVER BEFORE THE ATTENTION TURNS TO CONVECTIVE POTENTIAL COME AFTERNOON WITH A WAVE OVER ONTARIO HEADING TOWARDS NORTHERN MICHIGAN. TODAY...BATCH OF LOW/MID-LEVEL MOISTURE MOVING ACROSS NORTHERN LAKE MICHIGAN WILL MOVE SE ALONG A WEAK CONVERGENCE ZONE ON THE NE FLANK OF THE SURFACE CIRCULATION. CANNOT RULE OUT A FEW SHOWERS WITH THIS FEATURE ACROSS THE SOUTHERN CWA THIS MORNING INTO THE EARLY AFTERNOON HOURS. ADDITIONAL CLOUD COVER WILL MAKE INROADS ACROSS EASTERN UPPER. WITH FURTHER BL COOLING...HARD TO PICK A POINT IN THE CWA THAT WONT AT LEAST BE PARTLY CLOUDY...IF NOT MOSTLY CLOUDY TO START THE MORNING. THIS MOISTURE SHOULD EVOLVE INTO A CU FIELD BY MIDDAY...WITH MORE BREAKS IN THE CLOUDS DEVELOPING AS MIXING TAKES PLACE. THIS PROCESS MAY TAKE A BIT LONGER ACROSS AREAS ADJACENT TO WHITEFISH BAY AND THE ST. MARYS RIVER...AND ALSO FROM TVC TO HTL WHERE A TAD MORE LOW LEVEL CYCLONIC FLOW WILL BE PRESENT. MEANWHILE...SHORTWAVE OVER ONTARIO WILL BE SHIFTING SOUTHEAST... REACHING AROUND THE KEWEENAW PENINSULA BY MIDDAY...AND NORTHERN LAKE MICHIGAN BY 00Z. WITH A WAVE DROPPING OVERHEAD...ONE MIGHT EXPECT A MORE WELL-DEFINED SYNOPTIC SURFACE FEATURE WHICH WOULD FOCUS CONVECTION. NOT SO IN THIS CASE. RESIDUAL TROUGHING ACCOMPANYING THE WEAK CIRCULATION LOOKS TO DROP SOUTH OF THE CWA BETWEEN 18-21Z TIMEFRAME. THIS WILL LEAVE LAKE BREEZES/HIGHER TERRAIN AS THE PRIMARY LOW LEVEL FOCUSES FOR CONVECTION...WHICH WILL DEVELOP ACROSS EASTERN UPPER AND NE LOWER. COOLER H500 TEMPS FALLING TO -15C WILL ARRIVE THIS AFTERNOON WITH THE INCOMING WAVE...SERVING TO LOWER FREEZING LEVELS TO 11.3KFT. MODIFYING A 21Z NAM SOUNDING NEAR WEST BRANCH FOR A SURFACE PARCEL 78/60 YIELDS BETWEEN 700-900 J/KG OF ML CAPE AND NO CIN. WITH 0-6KM BULK SHEAR BETWEEN 40-50KTS SOUTH OF M-72...NOT OUT OF THE QUESTION THAT A FEW STORMS COULD CONTAIN ROTATION THAT WOULD GIVE UPDRAFTS A BOOST TO SUPPORT SEVERE HAIL AND DAMAGING WINDS. ALSO WILL HAVE TO WATCH FOR STORMS NEAR GRB TO DRIFT ACROSS THE LAKE LATE THIS AFTERNOON TO REACH THE NW LOWER MICHIGAN SHORELINE. TONIGHT...SHORTWAVE TROUGH WILL CLEAR THE AREA DURING THE EVENING AND SHOWERS AND THUNDERSTORMS WILL BE WINDING DOWN RATHER QUICKLY ACROSS THE SE AREAS. THEN...H850 TROUGH AXIS WILL DRIFT SOUTH OUT OF ONTARIO WITH PLENTY OF MOISTURE BLO 925MB WHICH WILL CLIP EASTERN UPPER/NE LOWER. COULD ALSO SEE LOW CLOUD COVER FORM A LITTLE BIT FARTHER WEST IF THERE IS SIGNIFICANT RAINFALL OVER THE HIGHER TERRAIN AREAS AND RAPID NOCTURNAL COOLING. SATURDAY AND SATURDAY NIGHT...NORTHERN MICHIGAN WILL BE WELL ENTRENCHED WITHIN NORTHERLY FLOW AS HEIGHTS BUILD ALOFT AND SURFACE HIGH PRESSURE BUILDS INTO THE REGION. SOME RESIDUAL LOW CLOUD COVER MAY LINGER INTO THE MORNING ACROSS NE LOWER AND AREAS ADJACENT TO SAG BAY...BUT ANY CLOUDS WILL BURN OFF INTO A CU FIELD. MID-LEVEL CAP WILL PUT A LID ON ANY DIURNAL CONVECTION...WHICH WILL ENSURE A DRY DAY. HIGHS IN THE MIDDLE TO UPPER 70S. CU FIELD WILL DISSIPATE BY EVENING LEAVING MOSTLY CLEAR SKIES FOR THE MOST PART. HIGH CLOUDS MAY DRIFT IN LATE FROM UPSTREAM MCS ACTION OVER MN/WI...BUT THATS ABOUT IT. LOWS IN THE 50S. REST OF THE FORECAST...VERY FEW CHANGES MADE. PRECIP CHANCES INCREASE HEADING INTO MONDAY AS A WARM FRONTAL FEATURE STALLS ACROSS THE CENTRAL GREAT LAKES...FOLLOWED BY A COLD FRONT ON TUESDAY. AS OF RIGHT NOW...MUCH OF THE HEAT WILL REMAIN WELL SOUTH OF THE REGION. THE WARMEST DAY STILL LOOKS TO BE ON MONDAY...BUT CLOUD COVER/PRECIP COULD POTENTIALLY LIMIT HIGHS SOMEWHAT. WILL LET THE PREVIOUS FORECAST RIDE AND SEE SHOW SHE PANS OUT. MPC && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1240 PM EDT FRI AUG 1 2008 LATEST UPDATE...AVIATION... .SYNOPSIS...(355 AM EDT FRI AUG 1 2008) A WAVE OF LOW PRESSURE WILL MOVE THROUGH THE GREAT LAKES REGION DURING THE AFTERNOON HOURS TODAY. THIS WAVE WILL HAVE THE POTENTIAL TO FIRE UP SHOWERS AND THUNDERSTORMS...ESPECIALLY OVER EASTERN AREAS. THIS SYSTEM WILL MOVE OUT TONIGHT...AND ALLOW FOR COOLER AND DRIER AIR TO MOVE IN FOR SATURDAY. HIGH PRESSURE WILL THEN BUILD IN FOR SATURDAY AND MOST OF SUNDAY...ALLOWING FOR DRY WEATHER. WARMER TEMPERATURES CAN BE EXPECTED THE FIRST HALF OF NEXT WEEK AS A FRONT MOVES IN. SHOWERS AND THUNDERSTORMS WILL BECOME POSSIBLE ONCE AGAIN FOR MONDAY THROUGH WEDNESDAY. && .SHORT TERM...(1005 AM EDT FRI AUG 1 2008) (TODAY) WE CONTINUE TO MONITOR SEVERE PROSPECTS. IN ADDITION TO THE SPC OUTLOOK AREA...WE ALSO ARE WONDERING ABOUT AREAS FARTHER N NEAR MOUNT PLEASANT. RUC GUIDANCE ADVERTISES A LOCAL MLCAPE MAX OF 1500+ J/KG IN THAT AREA. ALSO...A STRONGER BAND OF WLY FLOW AND 40+ KT 0-6KM SHEAR WILL BE CUTTING ACROSS THIS AREA BY AFTERNOON...LIKELY IN ASSOCIATION WITH THE VORT MAX CURRENTLY CROSSING NRN WI. CLOUDS OVER NRN LOWER MI HAVE ERODED...SO QUESTION IS WHAT EFFECT CONVECTIVE DEBRIS OVER WI WILL HAVE ON THIS AREA AS THEY CROSS THE LAKE. OTHERWISE...HAVE COMMENCED NOWCASTS FOR THE OTTAWA AND ALLEGAN COUNTIES TO ACCOUNT FOR ADVECTION FOG DEVELOPING OVER SE LAKE MI... THANKS TO DEWPOINTS IN THE LOW 70S STREAMING INTO THE AREA. DO NOT EXPECT THIS TO PERSIST TOO LONG...BUT IT WILL HAVE EFFECTS ON MARINE INTERESTS (SEE MARINE SECTION BELOW). && .LONG TERM...(1110 AM EDT FRI AUG 1 2008) (SATURDAY THROUGH FRIDAY) SEASONABLY MILD TEMPS ARE ANTICIPATED THIS WEEKEND. IT WILL TURN INCREASINGLY WARMER AND MORE HUMID SUNDAY NIGHT THROUGH EARLY NEXT WEEK ALONG WITH A THREAT FOR THUNDERSTORMS. WE WILL HAVE TO WATCH FOR POTENTIAL FOR SOME STRONG TO SEVERE STORMS IN THAT TIME FRAME DUE TO THE INCREASINGLY HUMID AND UNSTABLE AIR MASS. COOLER AND DRIER AIR WILL FILTER IN BEHIND THE COLD FRONT BEGINNING WEDNESDAY BUT ESPECIALLY FOR LATE NEXT WEEK. IN FACT BELOW NORMAL TEMPS ARE ANTICIPATED BY NEXT FRIDAY AS CANADIAN HIGH PRESSURE BUILDS IN. && .MARINE...(1005 AM EDT FRI AUG 1 2008) HAVE UPDATED THE FORECASTS TO INCLUDE PATCHY DENSE ADVECTION FOG THAT DEVELOPED MAINLY NEAR THE HOLLAND/GRAND HAVEN AREAS. THIS WILL LOWER VISIBILITIES TO A QUARTER MILE OR LESS IN SPOTS. EXPECT THE THREAT TO BE LIMITED IN DURATION AS NW FLOW BECOMES ESTABLISHED OVER THE LAKE BY AFTERNOON...WHICH SHOULD PUSH THE HIGHER DEWPOINT AIR OUT OF THE AREA AND PROMOTE MECHANICAL MIXING. NO OTHER CHANGES WERE MADE. && .AVIATION...(1240 PM EDT FRI AUG 1 2008) VFR CONDITIONS ANTICIPATED THROUGH 18Z SAT. BOTH NE AND SE LWR MI ARE MOST FAVORED FOR THUNDERSTORMS DEVELOPMENT AFTER 19Z. NE LWR MI IN AN AREA OF STRONG PVA AND SE LWR MI IN AN AREA OF FAIRLY STRONG INSTABILITY AND SFC CONVERGENCE. A TSTORM COULD CLIP THE JXN AND PERHAPS LAN TAF SITE AFTER 19Z... BUT MOST OF THE ACTIVITY WILL DEVELOP FURTHER EAST AND DRY WX SHOULD PREVAIL THIS AFTN ACROSS THE MAJORITY OF OUR AREA. THE POTENTIAL FOR FOG LOOKS LOWER TONIGHT THAN IT WAS LAST NIGHT. A CU FIELD WILL DEVELOP AT ALL TAF SITES BETWEEN 15Z AND 16Z SAT. && .HYDROLOGY...(355 AM EDT FRI AUG 1 2008) RIVER AND STREAM LEVELS ACROSS THE HYDROLOGIC SERVICE AREA HAVE NOW DROPPED DOWN TO NEAR TO SLIGHTLY BELOW NORMAL WITH THE LACK OF WIDESPREAD RAIN OVER THE PAST COUPLE OF WEEKS. CONVECTION THIS AFTERNOON DOES NOT LOOK TO HAVE MUCH OF A HYDRO THREAT. PRECIPITABLE WATERS WILL BE ONLY AROUND AN INCH...AND THE FLOW ALOFT IS FAIRLY STEADY. BASIN AVERAGES SHOULD REMAIN UNDER A QUARTER OF AN INCH WITH LOCALLY HEAVY DOWNPOURS POSSIBLE. THE MORE POTENTIALLY SIGNIFICANT PERIOD FOR HYDRO WILL BE THE FIRST HALF OF THE WEEK AS A FRONT WILL BE IN THE REGION AND THERE COULD POTENTIALLY BE WAVES OF HEAVY RAIN PRODUCING STORMS. THIS SCENARIO IS STILL QUITE UNCERTAIN...BUT WILL NEED TO BE MONITORED. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ SYNOPSIS: NJJ SHORT TERM: TJT LONG TERM: LAURENS MARINE: TJT AVIATION: LAURENS HYDROLOGY: NJJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1105 AM EDT FRI AUG 1 2008 .UPDATE... WV IMAGERY AND RUC ANALYSIS INDICATED A SHORTWAVE TROUGH MOVING THROUGH UPPER MI THATHELPED SUPPORT DIMINISHING/WEAKENING AREA OF SHRA/TSRA OVER THE CNTRL CWA. ANOTHER SHRTWV WAS LOCATED JUST NW OF CYQT. THE BEST FORCING WITH THE UPSTREAM SHRTWV SHOULD REMAIN NORTH AND EAST OF LAKE SUPERIOR. HOWEVER...SFC HEATING WITH TEMPS TO NEAR 80F AND DEWPOINTS IN THE UPPER 50S...WITH MLCAPE VALUES TO AROUND 1000 J/KG ...EXPECT ISOLD SHRA/TSRA TO REDEVELOP...ESPECIALLY ALONG LAKE BREEZE BOUNDARIES IN THE ERN CWA. 0-6 KM SHEAR VALUES AROUND 40 KT COULD ALSO SUPPORT ISOLD STRONG STORMS WITH SMALL HAIL AND 40 MPH WINDS. ONLY MINOR ADJUSTMENTS WERE MADE TO GOING GRIDS/FCST. .DISCUSSION... UPPER AIR PATTERN CONSISTS OF A 500 MB RIDGE ACROSS THE WESTERN HALF OF THE U.S. WITH TROUGHING OVER THE EAST AND PACIFIC NW. THERE IS A SHORTWAVE ACROSS THE ARROWHEAD OF MN AND THIS HAS BEEN KICKING OFF SOME SHOWERS AND THUNDERSTORMS THIS EVENING OVER MN. THIS SHORTWAVE WILL CONTINUE TO DIG SE AND AFFECT THE CWA TODAY WITH UPPER LEVEL RIDGING THEN BUILDING IN TONIGHT AND SAT BEFORE THE NAM SHOWS A SHORTWAVE TOPPING AND MOVING THROUGH THE RIDGE SAT NIGHT. NAM SHOWS SOME WEAK 850-500 MB Q-VECTOR CONVERGENCE ALONG WITH MARGINAL DEEP MOISTURE TODAY MOVING ACROSS THE AREA. GFS IS THE SAME WAY. WILL CUT POPS BACK TO SLIGHT CHANCE THIS MORNING. AS THIS AFTERNOON COMES...POSSIBILITY OF SOME LAKE BREEZES WILL HELP TO KICK OFF SOME THUNDERSTORMS AND WILL GO CHANCE POPS IN THE LAKE BREEZE PRONE CONVERGENCE AREAS ACROSS THE CENTRAL CWA. OVERALL...DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST TEMPERATURE WISE EXCEPT WARMED THEM UP A BIT SUN NIGHT IN DOWNSLOPE AREAS NEAR THE LAKESHORE TO 70 DEGREES OR SO. REMOVED POPS FROM SAT NIGHT AS GFS...NAM AND ECMWF ARE DRY AND THAT CONTINUED TO LOOK GOOD WITH 500 MB RIDGING IN CONTROL. WOULD NOT BE SURPRISED TO SEE SUNDAY DRY AS WELL...BUT CONFIDENCE IS LOW ENOUGH NOT TO REMOVE SLIGHT CHANCE POPS ACROSS THE WEST HALF FOR NOW. TEMPERATURES WILL CONTINUE TO BE SLIGHTLY ABOVE NORMAL. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... FOG THIS MORNING WILL QUICKLY DISSIPATE THIS MORNING...RESULTING IN VFR CONDITIONS THROUGH MUCH OF THE PERIOD. SHOWERS HAVE DEVELOPED UPSTREAM...ACROSS NORTHWESTERN LAKE SUPERIOR. AS A RESULT..EARLY SHOWERS AT CMX MAY TRANSITION TO SAW BY MID TO LATE MORNING. WILL NEED TO KEEP AN EYE ON THE POTENTIAL FOR TS BEFORE MORE STABLE AIR WORKS INTO THE AREA FROM MID AFTERNOON ON. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRESSURE WILL GENERALLY BE THE RULE...MINUS A BRIEF DISRUPTION BY A TROUGH CROSSING OVER THE AREA TONIGHT WITH WINDS GETTING UP TO 20KT. THE MAIN WEATHER MAKER IS STILL EXPECTED TO BE FOR THE LAST HALF OF THE WEEKEND...AS LOW PRESSURE DEVELOPS ACROSS THE NORTHERN PLAINS SATURDAY...BRINGING A TROUGH TO WESTERN LAKE SUPERIOR BY EARLY MONDAY AFTERNOON...AND TO THE LOWER GREAT LAKES BY TUESDAY MORNING. HIGH PRESSURE WILL THEN FILTER INTO THE AREA FROM THE NORTHERN PLAINS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...JLB DISCUSSION...GM AVIATION...KF MARINE...KF mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1110 AM EDT FRI AUG 1 2008 LATEST UPDATE...LONG TERM... .SYNOPSIS...(355 AM EDT FRI AUG 1 2008) A WAVE OF LOW PRESSURE WILL MOVE THROUGH THE GREAT LAKES REGION DURING THE AFTERNOON HOURS TODAY. THIS WAVE WILL HAVE THE POTENTIAL TO FIRE UP SHOWERS AND THUNDERSTORMS...ESPECIALLY OVER EASTERN AREAS. THIS SYSTEM WILL MOVE OUT TONIGHT...AND ALLOW FOR COOLER AND DRIER AIR TO MOVE IN FOR SATURDAY. HIGH PRESSURE WILL THEN BUILD IN FOR SATURDAY AND MOST OF SUNDAY...ALLOWING FOR DRY WEATHER. WARMER TEMPERATURES CAN BE EXPECTED THE FIRST HALF OF NEXT WEEK AS A FRONT MOVES IN. SHOWERS AND THUNDERSTORMS WILL BECOME POSSIBLE ONCE AGAIN FOR MONDAY THROUGH WEDNESDAY. && .SHORT TERM...(1005 AM EDT FRI AUG 1 2008) (TODAY) WE CONTINUE TO MONITOR SEVERE PROSPECTS. IN ADDITION TO THE SPC OUTLOOK AREA...WE ALSO ARE WONDERING ABOUT AREAS FARTHER N NEAR MOUNT PLEASANT. RUC GUIDANCE ADVERTISES A LOCAL MLCAPE MAX OF 1500+ J/KG IN THAT AREA. ALSO...A STRONGER BAND OF WLY FLOW AND 40+ KT 0-6KM SHEAR WILL BE CUTTING ACROSS THIS AREA BY AFTERNOON...LIKELY IN ASSOCIATION WITH THE VORT MAX CURRENTLY CROSSING NRN WI. CLOUDS OVER NRN LOWER MI HAVE ERODED...SO QUESTION IS WHAT EFFECT CONVECTIVE DEBRIS OVER WI WILL HAVE ON THIS AREA AS THEY CROSS THE LAKE. OTHERWISE...HAVE COMMENCED NOWCASTS FOR THE OTTAWA AND ALLEGAN COUNTIES TO ACCOUNT FOR ADVECTION FOG DEVELOPING OVER SE LAKE MI... THANKS TO DEWPOINTS IN THE LOW 70S STREAMING INTO THE AREA. DO NOT EXPECT THIS TO PERSIST TOO LONG...BUT IT WILL HAVE EFFECTS ON MARINE INTERESTS (SEE MARINE SECTION BELOW). && .LONG TERM...(1110 AM EDT FRI AUG 1 2008) (SATURDAY THROUGH FRIDAY) SEASONABLY MILD TEMPS ARE ANTICIPATED THIS WEEKEND. IT WILL TURN INCREASINGLY WARMER AND MORE HUMID SUNDAY NIGHT THROUGH EARLY NEXT WEEK ALONG WITH A THREAT FOR THUNDERSTORMS. WE WILL HAVE TO WATCH FOR POTENTIAL FOR SOME STRONG TO SEVERE STORMS IN THAT TIME FRAME DUE TO THE INCREASINGLY HUMID AND UNSTABLE AIR MASS. COOLER AND DRIER AIR WILL FILTER IN BEHIND THE COLD FRONT BEGINNING WEDNESDAY BUT ESPECIALLY FOR LATE NEXT WEEK. IN FACT BELOW NORMAL TEMPS ARE ANTICIPATED BY NEXT FRIDAY AS CANADIAN HIGH PRESSURE BUILDS IN. && .MARINE...(1005 AM EDT FRI AUG 1 2008) HAVE UPDATED THE FORECASTS TO INCLUDE PATCHY DENSE ADVECTION FOG THAT DEVELOPED MAINLY NEAR THE HOLLAND/GRAND HAVEN AREAS. THIS WILL LOWER VISIBILITIES TO A QUARTER MILE OR LESS IN SPOTS. EXPECT THE THREAT TO BE LIMITED IN DURATION AS NW FLOW BECOMES ESTABLISHED OVER THE LAKE BY AFTERNOON...WHICH SHOULD PUSH THE HIGHER DEWPOINT AIR OUT OF THE AREA AND PROMOTE MECHANICAL MIXING. NO OTHER CHANGES WERE MADE. && .AVIATION...(700 AM EDT FRI AUG 1 2008) THE MAIN FOCUS FOR THE TAFS IS IF/WHEN/WHERE TO PLACE A MENTION OF THUNDER OVER THE NEXT 24 HOURS. THE BEST CHANCE OF STORMS ON FRIDAY AFTERNOON LOOKS TO BE OVER EASTERN LOWER MI... SO WILL STILL CARRY VCTS IN JUST THE LAN AND JXN TAF SITES AFTER 20Z. WNW LOW LEVEL FLOW OFF LAKE MICHIGAN SHOULD KEEP THE OTHER SITES STABLE ENOUGH TO SERIOUSLY LIMIT THE THUNDER THREAT. THE POTENTIAL FOR FOG LOOKS LOWER TONIGHT THAN IT WAS LAST NIGHT. && .HYDROLOGY...(355 AM EDT FRI AUG 1 2008) RIVER AND STREAM LEVELS ACROSS THE HYDROLOGIC SERVICE AREA HAVE NOW DROPPED DOWN TO NEAR TO SLIGHTLY BELOW NORMAL WITH THE LACK OF WIDESPREAD RAIN OVER THE PAST COUPLE OF WEEKS. CONVECTION THIS AFTERNOON DOES NOT LOOK TO HAVE MUCH OF A HYDRO THREAT. PRECIPITABLE WATERS WILL BE ONLY AROUND AN INCH...AND THE FLOW ALOFT IS FAIRLY STEADY. BASIN AVERAGES SHOULD REMAIN UNDER A QUARTER OF AN INCH WITH LOCALLY HEAVY DOWNPOURS POSSIBLE. THE MORE POTENTIALLY SIGNIFICANT PERIOD FOR HYDRO WILL BE THE FIRST HALF OF THE WEEK AS A FRONT WILL BE IN THE REGION AND THERE COULD POTENTIALLY BE WAVES OF HEAVY RAIN PRODUCING STORMS. THIS SCENARIO IS STILL QUITE UNCERTAIN...BUT WILL NEED TO BE MONITORED. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ SYNOPSIS: NJJ SHORT TERM: TJT LONG TERM: LAURENS MARINE: TJT AVIATION: MJS HYDROLOGY: NJJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1039 AM EDT FRI AUG 1 2008 .UPDATE...SOMEWHAT COMPLICATED WX TO DEAL WITH OVER THE NEXT 12 HOURS. THE MOST OBVIOUS SURFACE FEATURE IS AN AREA OF HIGH PRESSURE IN THE EASTERN DAKOTAS. THIS IS PROVIDING A BACKGROUND WEAK NORTHWESTERLY LOW LEVEL FLOW. A COUPLE OF SURFACE TROFS/WEAK COLD FRONTS ARE SEEN...ONE FROM THE THUMB TO FAR NORTHERN IL...AND A VERY SUBTLE ONE THAT APPEARS TO RUN FROM NORTHERN WI THRU THE STRAITS AND ON TO FAR NORTHERN LK HURON. ALOFT...A WELL-DEFINED SHORTWAVE DIGGING ACROSS SUPERIOR WAS SUPPORTING AREAS OF DEEP CONVECTION ALL NIGHT. HOWEVER...PRECIP HAS BEEN WEAKENING SINCE SUNRISE. SHOWERS AND A FEW STORMS WERE LOCATED IN S CENTRAL SUPERIOR...AND IN NE WI. PRECIP TRENDS AND SVR POTENTIAL ARE THE MAIN CONCERNS. TODAY...WITH COOLER AIR ARRIVING ABOVE 750MB TODAY THANKS TO THE INCOMING SHORTWAVE...WE WILL HAVE A CHANCE TO FIRE OFF SURFACE-BASED CONVECTION. A 78/61 SURFACE PARCEL PRODUCES ABOUT 900J/KG OF MLCAPE...THAT SHOULD BE ABOUT THE TOP-END FOR INSTABILITY. THE LOW LEVEL FLOW IS AND WILL REMAIN WEAK...RESULTING IN MINIMAL SHEAR IN THE LOW LEVELS...BUT ALSO ALLOWING LAKE BREEZES TO DEVELOP AND PROVIDE ADDITIONAL TRIGGER MECHANISMS. NO MAJOR CONCERNS FOR STRONG STORMS NEAR AND NORTH OF THE BRIDGE... WHERE MORNING STRATUS HAS HINDERED HEATING. TO THE SOUTH...THE COMBINATION OF STRONG MID-LEVEL FLOW (WNW 500MB WINDS OF 45KT) AND LOWERING FREEZING LEVELS (FROM 12.5K TO 11K FEET THIS AFTERNOON)... WILL ALLOW FOR SOME STRONGER STORMS PRODUCING BOTH BRIEF GUSTY WINDS AND SMALL HAIL. AN ISOLATED SVR STORM OR TWO STILL SEEMS REASONABLE AWAY FROM THE IMMEDIATE LAKE MI COAST. WILL ADJUST TIMING FOR PRECIP AND CLOUD COVER A BIT IN THE GRIDS... THOUGH THIS WILL NOT HAVE MUCH IMPACT IN THE TEXT PRODUCTS. TEMPS LOOK DECENT...WE ALREADY HAD EASTERN UPPER MI ON THE COOL SIDE AND THAT LOOKS REALLY GOOD NOW. HEATING IN THE SE ZONES HAD BEEN INHIBITED BY WARM ADVECTION MID DECK...BUT THAT IS MOVING OUT NOW AND THEY HAVE PLENTY OF TIME TO WARM UP TO NEAR 80. JZ && .AVIATION...ISSUED 723 AM FRI AUG 1... IFR CLOUDS CONTINUE TO DRIFT SOUTH ACROSS EASTERN UPPER AND THE STRAITS AND WILL IMPACT PLN FOR A COUPLE HOURS THIS MORNING. ONCE THESE CLOUDS LIFT...WILL BE AWAITING THE ARRIVAL OF THUNDERSTORMS CURRENTLY MOVING ACROSS LAKE SUPERIOR AND NORTHERN WISCONSIN. TIMING TOOL HAS THESE CLUSTERS OF THUNDERSTORMS ARRIVING AROUND MIDDAY AT PLN AND TVC...WITH THE THREAT OF STORMS CONTINUING UNTIL MID-EVENING OR SO. THEREAFTER...SKIES WILL CLEAR AT TVC...BUT AN INCOMING LOW LEVEL TROUGH MAY BRING BACK MVFR IF NOT IFR CIGS TO APN AND PLN. MPC && .PREV DISCUSSION... /ISSUED 404 AM EDT FRI AUG 1 2008/ 02Z SURFACE/RUC ANALYSIS...AND IR/WV/RADAR IMAGERY SHOW RELATIVELY ZONAL FLOW ACROSS THE NORTHERN TIER OF THE CONUS ATOP A BROAD AND ELONGATED SOUTHERN CONUS RIDGE. SEVERAL SHORTWAVES CAN BE SEEN WITHIN THIS ZONAL FLOW...ONE PASSING ACROSS IN/OH...A MYRIAD OF WAVES OVER SASKETCHEWON/MANITOBA/ONTARIO...AND A DEEPER WAVE JUST OFFSHORE OF THE PAC NORTHWEST. CLUSTERS OF THUNDERSTORMS CONTINUE AT THIS HOUR OVER SOUTHERN ONTARIO/ARROWHEAD OF MN WITHIN THE LEFT EXIT REGION OF A 80KT JET STREAK/700-500MB -DIVQ/AND H850 TROUGH AXIS EXTENDING ACROSS ONTARIO/LAKE SUPERIOR INTO QUEBEC. LOW STRATUS CONTINUES TO DRIFT SOUTH ALONG THIS TROUGH TOWARDS EASTERN UPPER AIDED BY RAPID BL COOLING...WHILE OTHER STRATO-CU/CU OVER THE HIGHER TERRAIN OF UPPER MICHIGAN HAS BEEN DRIFTING ACROSS NORTHERN LAKE MICHIGAN TOWARDS NORTHERN LOWER WITH WHAT LOOKS LIKE A WEAK WARM FRONTAL SIGNATURE NE OF A SURFACE CIRCULATION OVER WISCONSIN. SOME SPOTTY SHOWERS HAVE BEEN NOTED WITHIN THIS CLOUD COVER HEADING TOWARDS THE LEELANAU PENINSULA. MAIN FORECAST CONCERNS TODAY CENTER ON NUISANT MORNING CLOUD COVER BEFORE THE ATTENTION TURNS TO CONVECTIVE POTENTIAL COME AFTERNOON WITH A WAVE OVER ONTARIO HEADING TOWARDS NORTHERN MICHIGAN. TODAY...BATCH OF LOW/MID-LEVEL MOISTURE MOVING ACROSS NORTHERN LAKE MICHIGAN WILL MOVE SE ALONG A WEAK CONVERGENCE ZONE ON THE NE FLANK OF THE SURFACE CIRCULATION. CANNOT RULE OUT A FEW SHOWERS WITH THIS FEATURE ACROSS THE SOUTHERN CWA THIS MORNING INTO THE EARLY AFTERNOON HOURS. ADDITIONAL CLOUD COVER WILL MAKE INROADS ACROSS EASTERN UPPER. WITH FURTHER BL COOLING...HARD TO PICK A POINT IN THE CWA THAT WONT AT LEAST BE PARTLY CLOUDY...IF NOT MOSTLY CLOUDY TO START THE MORNING. THIS MOISTURE SHOULD EVOLVE INTO A CU FIELD BY MIDDAY...WITH MORE BREAKS IN THE CLOUDS DEVELOPING AS MIXING TAKES PLACE. THIS PROCESS MAY TAKE A BIT LONGER ACROSS AREAS ADJACENT TO WHITEFISH BAY AND THE ST. MARYS RIVER...AND ALSO FROM TVC TO HTL WHERE A TAD MORE LOW LEVEL CYCLONIC FLOW WILL BE PRESENT. MEANWHILE...SHORTWAVE OVER ONTARIO WILL BE SHIFTING SOUTHEAST... REACHING AROUND THE KEWEENAW PENINSULA BY MIDDAY...AND NORTHERN LAKE MICHIGAN BY 00Z. WITH A WAVE DROPPING OVERHEAD...ONE MIGHT EXPECT A MORE WELL-DEFINED SYNOPTIC SURFACE FEATURE WHICH WOULD FOCUS CONVECTION. NOT SO IN THIS CASE. RESIDUAL TROUGHING ACCOMPANYING THE WEAK CIRCULATION LOOKS TO DROP SOUTH OF THE CWA BETWEEN 18-21Z TIMEFRAME. THIS WILL LEAVE LAKE BREEZES/HIGHER TERRAIN AS THE PRIMARY LOW LEVEL FOCUSES FOR CONVECTION...WHICH WILL DEVELOP ACROSS EASTERN UPPER AND NE LOWER. COOLER H500 TEMPS FALLING TO -15C WILL ARRIVE THIS AFTERNOON WITH THE INCOMING WAVE...SERVING TO LOWER FREEZING LEVELS TO 11.3KFT. MODIFYING A 21Z NAM SOUNDING NEAR WEST BRANCH FOR A SURFACE PARCEL 78/60 YIELDS BETWEEN 700-900 J/KG OF ML CAPE AND NO CIN. WITH 0-6KM BULK SHEAR BETWEEN 40-50KTS SOUTH OF M-72...NOT OUT OF THE QUESTION THAT A FEW STORMS COULD CONTAIN ROTATION THAT WOULD GIVE UPDRAFTS A BOOST TO SUPPORT SEVERE HAIL AND DAMAGING WINDS. ALSO WILL HAVE TO WATCH FOR STORMS NEAR GRB TO DRIFT ACROSS THE LAKE LATE THIS AFTERNOON TO REACH THE NW LOWER MICHIGAN SHORELINE. TONIGHT...SHORTWAVE TROUGH WILL CLEAR THE AREA DURING THE EVENING AND SHOWERS AND THUNDERSTORMS WILL BE WINDING DOWN RATHER QUICKLY ACROSS THE SE AREAS. THEN...H850 TROUGH AXIS WILL DRIFT SOUTH OUT OF ONTARIO WITH PLENTY OF MOISTURE BLO 925MB WHICH WILL CLIP EASTERN UPPER/NE LOWER. COULD ALSO SEE LOW CLOUD COVER FORM A LITTLE BIT FARTHER WEST IF THERE IS SIGNIFICANT RAINFALL OVER THE HIGHER TERRAIN AREAS AND RAPID NOCTURNAL COOLING. SATURDAY AND SATURDAY NIGHT...NORTHERN MICHIGAN WILL BE WELL ENTRENCHED WITHIN NORTHERLY FLOW AS HEIGHTS BUILD ALOFT AND SURFACE HIGH PRESSURE BUILDS INTO THE REGION. SOME RESIDUAL LOW CLOUD COVER MAY LINGER INTO THE MORNING ACROSS NE LOWER AND AREAS ADJACENT TO SAG BAY...BUT ANY CLOUDS WILL BURN OFF INTO A CU FIELD. MID-LEVEL CAP WILL PUT A LID ON ANY DIURNAL CONVECTION...WHICH WILL ENSURE A DRY DAY. HIGHS IN THE MIDDLE TO UPPER 70S. CU FIELD WILL DISSIPATE BY EVENING LEAVING MOSTLY CLEAR SKIES FOR THE MOST PART. HIGH CLOUDS MAY DRIFT IN LATE FROM UPSTREAM MCS ACTION OVER MN/WI...BUT THATS ABOUT IT. LOWS IN THE 50S. REST OF THE FORECAST...VERY FEW CHANGES MADE. PRECIP CHANCES INCREASE HEADING INTO MONDAY AS A WARM FRONTAL FEATURE STALLS ACROSS THE CENTRAL GREAT LAKES...FOLLOWED BY A COLD FRONT ON TUESDAY. AS OF RIGHT NOW...MUCH OF THE HEAT WILL REMAIN WELL SOUTH OF THE REGION. THE WARMEST DAY STILL LOOKS TO BE ON MONDAY...BUT CLOUD COVER/PRECIP COULD POTENTIALLY LIMIT HIGHS SOMEWHAT. WILL LET THE PREVIOUS FORECAST RIDE AND SEE SHOW SHE PANS OUT. MPC && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1005 AM EDT FRI AUG 1 2008 LATEST UPDATE...SHORT TERM...MARINE... .SYNOPSIS...(355 AM EDT FRI AUG 1 2008) A WAVE OF LOW PRESSURE WILL MOVE THROUGH THE GREAT LAKES REGION DURING THE AFTERNOON HOURS TODAY. THIS WAVE WILL HAVE THE POTENTIAL TO FIRE UP SHOWERS AND THUNDERSTORMS...ESPECIALLY OVER EASTERN AREAS. THIS SYSTEM WILL MOVE OUT TONIGHT...AND ALLOW FOR COOLER AND DRIER AIR TO MOVE IN FOR SATURDAY. HIGH PRESSURE WILL THEN BUILD IN FOR SATURDAY AND MOST OF SUNDAY...ALLOWING FOR DRY WEATHER. WARMER TEMPERATURES CAN BE EXPECTED THE FIRST HALF OF NEXT WEEK AS A FRONT MOVES IN. SHOWERS AND THUNDERSTORMS WILL BECOME POSSIBLE ONCE AGAIN FOR MONDAY THROUGH WEDNESDAY. && .SHORT TERM...(1005 AM EDT FRI AUG 1 2008) (TODAY) WE CONTINUE TO MONITOR SEVERE PROSPECTS. IN ADDITION TO THE SPC OUTLOOK AREA...WE ALSO ARE WONDERING ABOUT AREAS FARTHER N NEAR MOUNT PLEASANT. RUC GUIDANCE ADVERTISES A LOCAL MLCAPE MAX OF 1500+ J/KG IN THAT AREA. ALSO...A STRONGER BAND OF WLY FLOW AND 40+ KT 0-6KM SHEAR WILL BE CUTTING ACROSS THIS AREA BY AFTERNOON...LIKELY IN ASSOCIATION WITH THE VORT MAX CURRENTLY CROSSING NRN WI. CLOUDS OVER NRN LOWER MI HAVE ERODED...SO QUESTION IS WHAT EFFECT CONVECTIVE DEBRIS OVER WI WILL HAVE ON THIS AREA AS THEY CROSS THE LAKE. OTHERWISE...HAVE COMMENCED NOWCASTS FOR THE OTTAWA AND ALLEGAN COUNTIES TO ACCOUNT FOR ADVECTION FOG DEVELOPING OVER SE LAKE MI... THANKS TO DEWPOINTS IN THE LOW 70S STREAMING INTO THE AREA. DO NOT EXPECT THIS TO PERSIST TOO LONG...BUT IT WILL HAVE EFFECTS ON MARINE INTERESTS (SEE MARINE SECTION BELOW). && .LONG TERM...(355 AM EDT FRI AUG 1 2008) (SUNDAY NIGHT THROUGH THURSDAY) THE MAIN CHALLENGE IN THE LONG TERM DEALS WITH THE TEMPERATURES EARLY NEXT WEEK. SEVERAL RUNS AGO MODELS SUPPORTED TEMPERATURES INTO THE 90S. HOWEVER...RECENT MODEL TRENDS SUPPORT A LOWERING OF THE HIGH TEMPERATURES MONDAY INTO TUESDAY TIMEFRAME. WE MAY STRUGGLE TO TOP 90...ESPECIALLY WITH THE POTENTIAL FOR SOME CONVECTION. WITH A COLD FRONT TO SWING THROUGH THE REGION TUE NIGHT INTO WED...THE WEATHER WILL TURN WARMER AND INCREASINGLY HUMID. SCATTERED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE UNTIL THE COLD FRONT ARRIVES. THE HIGH PRESSURE SYSTEM THAT ARRIVES BEHIND THE COLD FRONT ORIGINATES FROM CENTRAL CANADA...THUS WE MAY END UP WITH BELOW NORMAL TEMPERATURES. && .MARINE...(1005 AM EDT FRI AUG 1 2008) HAVE UPDATED THE FORECASTS TO INCLUDE PATCHY DENSE ADVECTION FOG THAT DEVELOPED MAINLY NEAR THE HOLLAND/GRAND HAVEN AREAS. THIS WILL LOWER VISIBILITIES TO A QUARTER MILE OR LESS IN SPOTS. EXPECT THE THREAT TO BE LIMITED IN DURATION AS NW FLOW BECOMES ESTABLISHED OVER THE LAKE BY AFTERNOON...WHICH SHOULD PUSH THE HIGHER DEWPOINT AIR OUT OF THE AREA AND PROMOTE MECHANICAL MIXING. NO OTHER CHANGES WERE MADE. && .AVIATION...(700 AM EDT FRI AUG 1 2008) THE MAIN FOCUS FOR THE TAFS IS IF/WHEN/WHERE TO PLACE A MENTION OF THUNDER OVER THE NEXT 24 HOURS. THE BEST CHANCE OF STORMS ON FRIDAY AFTERNOON LOOKS TO BE OVER EASTERN LOWER MI... SO WILL STILL CARRY VCTS IN JUST THE LAN AND JXN TAF SITES AFTER 20Z. WNW LOW LEVEL FLOW OFF LAKE MICHIGAN SHOULD KEEP THE OTHER SITES STABLE ENOUGH TO SERIOUSLY LIMIT THE THUNDER THREAT. THE POTENTIAL FOR FOG LOOKS LOWER TONIGHT THAN IT WAS LAST NIGHT. && .HYDROLOGY...(355 AM EDT FRI AUG 1 2008) RIVER AND STREAM LEVELS ACROSS THE HYDROLOGIC SERVICE AREA HAVE NOW DROPPED DOWN TO NEAR TO SLIGHTLY BELOW NORMAL WITH THE LACK OF WIDESPREAD RAIN OVER THE PAST COUPLE OF WEEKS. CONVECTION THIS AFTERNOON DOES NOT LOOK TO HAVE MUCH OF A HYDRO THREAT. PRECIPITABLE WATERS WILL BE ONLY AROUND AN INCH...AND THE FLOW ALOFT IS FAIRLY STEADY. BASIN AVERAGES SHOULD REMAIN UNDER A QUARTER OF AN INCH WITH LOCALLY HEAVY DOWNPOURS POSSIBLE. THE MORE POTENTIALLY SIGNIFICANT PERIOD FOR HYDRO WILL BE THE FIRST HALF OF THE WEEK AS A FRONT WILL BE IN THE REGION AND THERE COULD POTENTIALLY BE WAVES OF HEAVY RAIN PRODUCING STORMS. THIS SCENARIO IS STILL QUITE UNCERTAIN...BUT WILL NEED TO BE MONITORED. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ SYNOPSIS: NJJ SHORT TERM: TJT LONG TERM: MJS MARINE: TJT AVIATION: MJS HYDROLOGY: NJJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 723 AM EDT FRI AUG 1 2008 .AVIATION...IFR CLOUDS CONTINUE TO DRIFT SOUTH ACROSS EASTERN UPPER AND THE STRAITS AND WILL IMPACT PLN FOR A COUPLE HOURS THIS MORNING. ONCE THESE CLOUDS LIFT...WILL BE AWAITING THE ARRIVAL OF THUNDERSTORMS CURRENTLY MOVING ACROSS LAKE SUPERIOR AND NORTHERN WISCONSIN. TIMING TOOL HAS THESE CLUSTERS OF THUNDERSTORMS ARRIVING AROUND MIDDAY AT PLN AND TVC...WITH THE THREAT OF STORMS CONTINUING UNTIL MID-EVENING OR SO. THEREAFTER...SKIES WILL CLEAR AT TVC...BUT AN INCOMING LOW LEVEL TROUGH MAY BRING BACK MVFR IF NOT IFR CIGS TO APN AND PLN. MPC && .PREV DISCUSSION... /ISSUED 404 AM EDT FRI AUG 1 2008/ DISCUSSION...02Z SURFACE/RUC ANALYSIS...AND IR/WV/RADAR IMAGERY SHOW RELATIVELY ZONAL FLOW ACROSS THE NORTHERN TIER OF THE CONUS ATOP A BROAD AND ELONGATED SOUTHERN CONUS RIDGE. SEVERAL SHORTWAVES CAN BE SEEN WITHIN THIS ZONAL FLOW...ONE PASSING ACROSS IN/OH...A MYRIAD OF WAVES OVER SASKETCHEWON/MANITOBA/ONTARIO...AND A DEEPER WAVE JUST OFFSHORE OF THE PAC NORTHWEST. CLUSTERS OF THUNDERSTORMS CONTINUE AT THIS HOUR OVER SOUTHERN ONTARIO/ARROWHEAD OF MN WITHIN THE LEFT EXIT REGION OF A 80KT JET STREAK/700-500MB -DIVQ/AND H850 TROUGH AXIS EXTENDING ACROSS ONTARIO/LAKE SUPERIOR INTO QUEBEC. LOW STRATUS CONTINUES TO DRIFT SOUTH ALONG THIS TROUGH TOWARDS EASTERN UPPER AIDED BY RAPID BL COOLING...WHILE OTHER STRATO-CU/CU OVER THE HIGHER TERRAIN OF UPPER MICHIGAN HAS BEEN DRIFTING ACROSS NORTHERN LAKE MICHIGAN TOWARDS NORTHERN LOWER WITH WHAT LOOKS LIKE A WEAK WARM FRONTAL SIGNATURE NE OF A SURFACE CIRCULATION OVER WISCONSIN. SOME SPOTTY SHOWERS HAVE BEEN NOTED WITHIN THIS CLOUD COVER HEADING TOWARDS THE LEELANAU PENINSULA. MAIN FORECAST CONCERNS TODAY CENTER ON NUISANT MORNING CLOUD COVER BEFORE THE ATTENTION TURNS TO CONVECTIVE POTENTIAL COME AFTERNOON WITH A WAVE OVER ONTARIO HEADING TOWARDS NORTHERN MICHIGAN. TODAY...BATCH OF LOW/MID-LEVEL MOISTURE MOVING ACROSS NORTHERN LAKE MICHIGAN WILL MOVE SE ALONG A WEAK CONVERGENCE ZONE ON THE NE FLANK OF THE SURFACE CIRCULATION. CANNOT RULE OUT A FEW SHOWERS WITH THIS FEATURE ACROSS THE SOUTHERN CWA THIS MORNING INTO THE EARLY AFTERNOON HOURS. ADDITIONAL CLOUD COVER WILL MAKE INROADS ACROSS EASTERN UPPER. WITH FURTHER BL COOLING...HARD TO PICK A POINT IN THE CWA THAT WONT AT LEAST BE PARTLY CLOUDY...IF NOT MOSTLY CLOUDY TO START THE MORNING. THIS MOISTURE SHOULD EVOLVE INTO A CU FIELD BY MIDDAY...WITH MORE BREAKS IN THE CLOUDS DEVELOPING AS MIXING TAKES PLACE. THIS PROCESS MAY TAKE A BIT LONGER ACROSS AREAS ADJACENT TO WHITEFISH BAY AND THE ST. MARYS RIVER...AND ALSO FROM TVC TO HTL WHERE A TAD MORE LOW LEVEL CYCLONIC FLOW WILL BE PRESENT. MEANWHILE...SHORTWAVE OVER ONTARIO WILL BE SHIFTING SOUTHEAST...REACHING AROUND THE KEWEENAW PENINSULA BY MIDDAY...AND NORTHERN LAKE MICHIGAN BY 00Z. WITH A WAVE DROPPING OVERHEAD...ONE MIGHT EXPECT A MORE WELL-DEFINED SYNOPTIC SURFACE FEATURE WHICH WOULD FOCUS CONVECTION. NOT SO IN THIS CASE. RESIDUAL TROUGHING ACCOMPANYING THE WEAK CIRCULATION LOOKS TO DROP SOUTH OF THE CWA BETWEEN 18-21Z TIMEFRAME. THIS WILL LEAVE LAKE BREEZES/HIGHER TERRAIN AS THE PRIMARY LOW LEVEL FOCUSES FOR CONVECTION...WHICH WILL DEVELOP ACROSS EASTERN UPPER AND NE LOWER. COOLER H500 TEMPS FALLING TO -15C WILL ARRIVE THIS AFTERNOON WITH THE INCOMING WAVE...SERVING TO LOWER FREEZING LEVELS TO 11.3KFT. MODIFYING A 21Z NAM SOUNDING NEAR WEST BRANCH FOR A SURFACE PARCEL 78/60 YIELDS BETWEEN 700-900 J/KG OF ML CAPE AND NO CIN. WITH 0-6KM BULK SHEAR BETWEEN 40-50KTS SOUTH OF M-72...NOT OUT OF THE QUESTION THAT A FEW STORMS COULD CONTAIN ROTATION THAT WOULD GIVE UPDRAFTS A BOOST TO SUPPORT SEVERE HAIL AND DAMAGING WINDS. ALSO WILL HAVE TO WATCH FOR STORMS NEAR GRB TO DRIFT ACROSS THE LAKE LATE THIS AFTERNOON TO REACH THE NW LOWER MICHIGAN SHORELINE. TONIGHT...SHORTWAVE TROUGH WILL CLEAR THE AREA DURING THE EVENING AND SHOWERS AND THUNDERSTORMS WILL BE WINDING DOWN RATHER QUICKLY ACROSS THE SE AREAS. THEN...H850 TROUGH AXIS WILL DRIFT SOUTH OUT OF ONTARIO WITH PLENTY OF MOISTURE BLO 925MB WHICH WILL CLIP EASTERN UPPER/NE LOWER. COULD ALSO SEE LOW CLOUD COVER FORM A LITTLE BIT FARTHER WEST IF THERE IS SIGNIFICANT RAINFALL OVER THE HIGHER TERRAIN AREAS AND RAPID NOCTURNAL COOLING. SATURDAY AND SATURDAY NIGHT...NORTHERN MICHIGAN WILL BE WELL ENTRENCHED WITHIN NORTHERLY FLOW AS HEIGHTS BUILD ALOFT AND SURFACE HIGH PRESSURE BUILDS INTO THE REGION. SOME RESIDUAL LOW CLOUD COVER MAY LINGER INTO THE MORNING ACROSS NE LOWER AND AREAS ADJACENT TO SAG BAY...BUT ANY CLOUDS WILL BURN OFF INTO A CU FIELD. MID-LEVEL CAP WILL PUT A LID ON ANY DIURNAL CONVECTION...WHICH WILL ENSURE A DRY DAY. HIGHS IN THE MIDDLE TO UPPER 70S. CU FIELD WILL DISSIPATE BY EVENING LEAVING MOSTLY CLEAR SKIES FOR THE MOST PART. HIGH CLOUDS MAY DRIFT IN LATE FROM UPSTREAM MCS ACTION OVER MN/WI...BUT THATS ABOUT IT. LOWS IN THE 50S. REST OF THE FORECAST...VERY FEW CHANGES MADE. PRECIP CHANCES INCREASE HEADING INTO MONDAY AS A WARM FRONTAL FEATURE STALLS ACROSS THE CENTRAL GREAT LAKES...FOLLOWED BY A COLD FRONT ON TUESDAY. AS OF RIGHT NOW...MUCH OF THE HEAT WILL REMAIN WELL SOUTH OF THE REGION. THE WARMEST DAY STILL LOOKS TO BE ON MONDAY...BUT CLOUD COVER/PRECIP COULD POTENTIALLY LIMIT HIGHS SOMEWHAT. WILL LET THE PREVIOUS FORECAST RIDE AND SEE SHOW SHE PANS OUT. MPC && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 404 AM EDT FRI AUG 1 2008 .DISCUSSION...02Z SURFACE/RUC ANALYSIS...AND IR/WV/RADAR IMAGERY SHOW RELATIVELY ZONAL FLOW ACROSS THE NORTHERN TIER OF THE CONUS ATOP A BROAD AND ELONGATED SOUTHERN CONUS RIDGE. SEVERAL SHORTWAVES CAN BE SEEN WITHIN THIS ZONAL FLOW...ONE PASSING ACROSS IN/OH...A MYRIAD OF WAVES OVER SASKETCHEWON/MANITOBA/ONTARIO...AND A DEEPER WAVE JUST OFFSHORE OF THE PAC NORTHWEST. CLUSTERS OF THUNDERSTORMS CONTINUE AT THIS HOUR OVER SOUTHERN ONTARIO/ARROWHEAD OF MN WITHIN THE LEFT EXIT REGION OF A 80KT JET STREAK/700-500MB -DIVQ/AND H850 TROUGH AXIS EXTENDING ACROSS ONTARIO/LAKE SUPERIOR INTO QUEBEC. LOW STRATUS CONTINUES TO DRIFT SOUTH ALONG THIS TROUGH TOWARDS EASTERN UPPER AIDED BY RAPID BL COOLING...WHILE OTHER STRATO-CU/CU OVER THE HIGHER TERRAIN OF UPPER MICHIGAN HAS BEEN DRIFTING ACROSS NORTHERN LAKE MICHIGAN TOWARDS NORTHERN LOWER WITH WHAT LOOKS LIKE A WEAK WARM FRONTAL SIGNATURE NE OF A SURFACE CIRCULATION OVER WISCONSIN. SOME SPOTTY SHOWERS HAVE BEEN NOTED WITHIN THIS CLOUD COVER HEADING TOWARDS THE LEELANAU PENINSULA. MAIN FORECAST CONCERNS TODAY CENTER ON NUISANT MORNING CLOUD COVER BEFORE THE ATTENTION TURNS TO CONVECTIVE POTENTIAL COME AFTERNOON WITH A WAVE OVER ONTARIO HEADING TOWARDS NORTHERN MICHIGAN. TODAY...BATCH OF LOW/MID-LEVEL MOISTURE MOVING ACROSS NORTHERN LAKE MICHIGAN WILL MOVE SE ALONG A WEAK CONVERGENCE ZONE ON THE NE FLANK OF THE SURFACE CIRCULATION. CANNOT RULE OUT A FEW SHOWERS WITH THIS FEATURE ACROSS THE SOUTHERN CWA THIS MORNING INTO THE EARLY AFTERNOON HOURS. ADDITIONAL CLOUD COVER WILL MAKE INROADS ACROSS EASTERN UPPER. WITH FURTHER BL COOLING...HARD TO PICK A POINT IN THE CWA THAT WONT AT LEAST BE PARTLY CLOUDY...IF NOT MOSTLY CLOUDY TO START THE MORNING. THIS MOISTURE SHOULD EVOLVE INTO A CU FIELD BY MIDDAY...WITH MORE BREAKS IN THE CLOUDS DEVELOPING AS MIXING TAKES PLACE. THIS PROCESS MAY TAKE A BIT LONGER ACROSS AREAS ADJACENT TO WHITEFISH BAY AND THE ST. MARYS RIVER...AND ALSO FROM TVC TO HTL WHERE A TAD MORE LOW LEVEL CYCLONIC FLOW WILL BE PRESENT. MEANWHILE...SHORTWAVE OVER ONTARIO WILL BE SHIFTING SOUTHEAST...REACHING AROUND THE KEWEENAW PENINSULA BY MIDDAY...AND NORTHERN LAKE MICHIGAN BY 00Z. WITH A WAVE DROPPING OVERHEAD...ONE MIGHT EXPECT A MORE WELL-DEFINED SYNOPTIC SURFACE FEATURE WHICH WOULD FOCUS CONVECTION. NOT SO IN THIS CASE. RESIDUAL TROUGHING ACCOMPANYING THE WEAK CIRCULATION LOOKS TO DROP SOUTH OF THE CWA BETWEEN 18-21Z TIMEFRAME. THIS WILL LEAVE LAKE BREEZES/HIGHER TERRAIN AS THE PRIMARY LOW LEVEL FOCUSES FOR CONVECTION...WHICH WILL DEVELOP ACROSS EASTERN UPPER AND NE LOWER. COOLER H500 TEMPS FALLING TO -15C WILL ARRIVE THIS AFTERNOON WITH THE INCOMING WAVE...SERVING TO LOWER FREEZING LEVELS TO 11.3KFT. MODIFYING A 21Z NAM SOUNDING NEAR WEST BRANCH FOR A SURFACE PARCEL 78/60 YIELDS BETWEEN 700-900 J/KG OF ML CAPE AND NO CIN. WITH 0-6KM BULK SHEAR BETWEEN 40-50KTS SOUTH OF M-72...NOT OUT OF THE QUESTION THAT A FEW STORMS COULD CONTAIN ROTATION THAT WOULD GIVE UPDRAFTS A BOOST TO SUPPORT SEVERE HAIL AND DAMAGING WINDS. ALSO WILL HAVE TO WATCH FOR STORMS NEAR GRB TO DRIFT ACROSS THE LAKE LATE THIS AFTERNOON TO REACH THE NW LOWER MICHIGAN SHORELINE. TONIGHT...SHORTWAVE TROUGH WILL CLEAR THE AREA DURING THE EVENING AND SHOWERS AND THUNDERSTORMS WILL BE WINDING DOWN RATHER QUICKLY ACROSS THE SE AREAS. THEN...H850 TROUGH AXIS WILL DRIFT SOUTH OUT OF ONTARIO WITH PLENTY OF MOISTURE BLO 925MB WHICH WILL CLIP EASTERN UPPER/NE LOWER. COULD ALSO SEE LOW CLOUD COVER FORM A LITTLE BIT FARTHER WEST IF THERE IS SIGNIFICANT RAINFALL OVER THE HIGHER TERRAIN AREAS AND RAPID NOCTURNAL COOLING. SATURDAY AND SATURDAY NIGHT...NORTHERN MICHIGAN WILL BE WELL ENTRENCHED WITHIN NORTHERLY FLOW AS HEIGHTS BUILD ALOFT AND SURFACE HIGH PRESSURE BUILDS INTO THE REGION. SOME RESIDUAL LOW CLOUD COVER MAY LINGER INTO THE MORNING ACROSS NE LOWER AND AREAS ADJACENT TO SAG BAY...BUT ANY CLOUDS WILL BURN OFF INTO A CU FIELD. MID-LEVEL CAP WILL PUT A LID ON ANY DIURNAL CONVECTION...WHICH WILL ENSURE A DRY DAY. HIGHS IN THE MIDDLE TO UPPER 70S. CU FIELD WILL DISSIPATE BY EVENING LEAVING MOSTLY CLEAR SKIES FOR THE MOST PART. HIGH CLOUDS MAY DRIFT IN LATE FROM UPSTREAM MCS ACTION OVER MN/WI...BUT THATS ABOUT IT. LOWS IN THE 50S. REST OF THE FORECAST...VERY FEW CHANGES MADE. PRECIP CHANCES INCREASE HEADING INTO MONDAY AS A WARM FRONTAL FEATURE STALLS ACROSS THE CENTRAL GREAT LAKES...FOLLOWED BY A COLD FRONT ON TUESDAY. AS OF RIGHT NOW...MUCH OF THE HEAT WILL REMAIN WELL SOUTH OF THE REGION. THE WARMEST DAY STILL LOOKS TO BE ON MONDAY...BUT CLOUD COVER/PRECIP COULD POTENTIALLY LIMIT HIGHS SOMEWHAT. WILL LET THE PREVIOUS FORECAST RIDE AND SEE SHOW SHE PANS OUT. MPC && .PREV DISCUSSION... /ISSUED 126 AM EDT FRI AUG 1 2008/ AVIATION...IFR-MVFR CONDITIONS WILL CONTINUE TO DEVELOP OVERNIGHT FROM THE TIP OF THE MITT...SOUTHEAST INTO NORTHEAST LOWER MICHIGAN. BKN 5-8KFT CEILINGS ASSOCIATED WITH A WEAK VORT MAX AND ILL DEFINED WARM FRONT OVER WISCONSIN WILL DRIFT INTO NORTHWEST LOWER MICHIGAN...BUT CEILINGS WILL REMAIN AT VFR. THE LOWEST CEILINGS WILL LIKELY DEVELOP AT KPLN AND KAPN...PERHAPS STARTING OFF AS SOME PATCHY FOG...LIFTING INTO A STRATUS DECK BY DAYBREAK. OTHERWISE...THE MVFR CONDITIONS WILL LIKELY SWEEP INTO ALPENA OVERNIGHT. ALL TAF SITES WILL BECOME VFR DURING THE LATE MORNING HOURS...BUT A DISTURBANCE WILL BRING A SLIGHT CHANCE OF A SHOWER TO NORTHEAST LOWER MICHIGAN DURING THE AFTERNOON HOURS. KAS && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MARQUETTE MI 100 AM EDT FRI AUG 1 2008 UPDATED FOR 06Z TAF ISSUANCE .UPDATE... BUMPED UP POPS FM 20 TO 30 PCT OVER THE NW LATE TNGT AS SCT SHRA/ TSRA HAVE DVLPD OVER NRN MN IN LEFT EXIT OF FAIRLY STRONG H3 JET MAX DIGGING SEWD NEAR LK WINNIPEG. LATEST RUC/GFS SHOW SOME FAIRLY IMPRESSIVE DPVA/DEEP LYR H85-3 QVECTOR CNVGC/UPR DVGC IN LEFT EXIT OF THE ACCOMPANYING JET MAX IMPACTING THE NW ZNS ON THE CYC SIDE OF THE JET AXIS AFT 06Z. HOWEVER...WEAK CNVGC ALG THE ATTENDANT COLD FNT AND LATE ARRIVAL TIME WITH NOCTURNAL COOLING WARRANT NO MORE THAN A 30 POP. ALSO ADDED SOME PATCHY FOG OVER THE ERN ZNS LATE TNGT WITH WEAK HI PRES RDG DOMINATING THERE FARTHER DOWNSTREAM THRU SUNRISE AND FCST LO TEMPS LIKELY GOING BELOW CROSSOVER DWPT IN THE UPR 50S. && .SYNOPSIS... WATER VAPOR IMAGERY AND RUC SHOWING A MID LEVEL LOW OVER SOUTHWEST QUEBEC...A WEAK RIDGE EXTENDS NORTH ACROSS WESTERN ONTARIO...AND ANOTHER LOW OVER CENTRAL SASKATCHEWAN. A BROAD RIDGE IS OVER THE SOUTHERN ROCKIES. WEAK SHORTWAVE IS MOVING INTO THE RIDGE AREA OVER NORTHERN MINNESOTA. SURFACE ANALYSIS DEPICTS A RIDGE OVER THE UPPER GREAT LAKES THIS MORNING...WITH A WEAK FRONTAL SYSTEM OVER NORTHERN MINNESOTA. && .SHORT TERM... (TONIGHT AND FRIDAY) THE 500MB RIDGE WILL NOT LAST LONG...AS THE LOW OVER THE THE WESTERN CANADIAN PROVINCES EJECT A WAVE TOWARDS UPPER MICHIGAN THIS AFTERNOON INTO TONIGHT. IT SHOULD DIP AND CUT OFF OVER EASTERN LAKE SUPERIOR AND NORTHERN LAKE HURON LATE FRIDAY AFTERNOON. THIS SHOULD ACT TO ASSIST THE LOW LEVEL CONVERGENCE ALREADY IN PLACE OVER EASTERN UPPER MICHIGAN...RESULTING IN SHOWERS AND THUNDERSTORMS. .LONG TERM... (FRI NIGHT THRU THU) FRI NIGHT/SAT...IN THE WAKE OF SHORTWAVE THAT PASSES FRI...MID/UPPER RIDGE WILL APPROACH THE UPPER GREAT LAKES WITH ASSOCIATED SFC HIGH PRES SETTLING OVER THE AREA. SO...TRANQUIL WEATHER IS EXPECTED. WITH SFC HIGH REACHING WRN UPPER MI LATE FRI NIGHT...IT WILL BE COOLEST OVER THE W. SINCE AIRMASS FROM A PRECIPITABLE WATER STANDPOINT IS NOT EXCESSIVELY DRY (VALUES OF 0.75-1 INCH AREN`T MUCH BLO NORMAL FOR THIS TIME OF YEAR)...WILL NOT GO ANY LWR THAN THE LWR END OF MOS GUIDANCE (AROUND 50F IN THE TYPICAL COOL SPOTS). OTHERWISE...IN GENERAL...MID 50S SHOULD BE MOST COMMON ACROSS THE FCST AREA. SHOULD BE A NICE EARLY AUG DAY SAT WITH A MIX OF SUN AND AFTN CU. LAKE BREEZES WILL DOMINATE OFF LAKE SUPERIOR WITH LAKE BREEZE DEVELOPING OFF LAKE MICHIGAN IN THE AFTN. SUN THRU THU...RIDGE OVER THE SW STATES IS STILL ON TRACK TO EXPAND FROM THE SW STATES ACROSS THE SRN CONUS THIS WEEKEND/EARLY NEXT WEEK. GFS/ECWMF/UKMET/CANADIAN ARE THEN MOVING TOWARD AGREEMENT THAT A SE CANADA/NE CONUS TROF WILL THEN TAKE SHAPE MIDDLE TO END OF NEXT WEEK...A TREND THAT HAS BEEN HINTED AT THE LAST COUPLE OF DAYS. AS A RESULT...ABOVE NORMAL TEMPS EARLY IN THE PERIOD (POSSIBLY ONE HOT/HUMID DAY) WILL TREND DOWN TO NORMAL AND POSSIBLY A LITTLE BELOW NORMAL BY THU. TIMING OF COLD FRONT INITIATING THE COOL DOWN IS FAIRLY WELL AGREED UPON AT THE MOMENT BY THE MODELS...PROBABLY CROSSING UPPER MI AT SOME POINT MON/MON NIGHT. UNTIL IT PASSES... THERE WILL BE A RISK OF SHRA/TSRA SUN/MON. WHILE SVR STORMS CAN`T BE RULED OUT...THE GREATER POTENTIAL OF SVR MAY STAY S OF THE FCST AREA AS THERE IS SOME INDICATION THAT A WARM FRONT/BOUNDARY WILL BE SET UP ACROSS MN/WI TO THE LOWER GREAT LAKES...AND THAT MAY FOCUS THE STRONGEST CONVECTION THERE. ALTHOUGH FROPA SHOULD OCCUR BY TUE MORNING...WILL LINGER POPS INTO TUE TO COVER POSSIBLE TIMING CHANGES WITH THE FRONT. IT APPEARS WED AND THU SHOULD THEN BE DRY IN THE WAKE OF THE COLD FRONT. HOWEVER...THERE CERTAINLY COULD BE ISOLD SHRA/TSRA AT TIMES AS UPPER FLOW BECOMES MORE NW SINCE THAT IS A PATTERN THAT OFTEN FAVORS ISOLD/SCT CONVECTION DURING THE SUMMER. HOWEVER...CONFIDENCE IS MUCH TOO LOW RIGHT NOW TO INCLUDE A MENTION...PARTICULARLY SINCE THERE IS SOME DISAGREEMENT ON THE EXACT EVOLUTION OF THE UPPER FLOW. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... ALTHOUGH THERE MAY BE SOME RADIATION FOG AT SAW BEFORE MORE MID CLD IN ADVANCE OF SHRTWV DIGGING SEWD FM SCNTRL CAN INVADES UPR MI LATER TNGT...EXPECT VFR CONDITIONS TO PREDOMINATE THIS FCST PD. EARLIER ARRIVAL OF THIS CLD ESPECIALLY AT CMX HAS REDUCED POTENTIAL FOR MORE SUBSTANTIVE RADIATION FOG...SO FCST NOTHING WORSE THAN AN MVFR VSBY AND ONLY AT SAW BEFORE BKN CLDS ARRIVE LATER. SOME -SHRA WITH ISOLD TS ARE ALSO PSBL TOWARD DAWN AT CMX AND THEN LATER THIS MRNG AT SAW. DRYING/LK STABILIZATION WL END THE SHRA CHCS NW TO SE THIS AFTN AND CONTINUE VFR CONDITIONS THRU TNGT. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... WINDS WILL REMAIN LIGHT UNDER THE RIDGE OVER THE UPPER GREAT LAKES. A WEAK TROUGH WILL DROP SOUTH ACROSS LAKE SUPERIOR LATE FRIDAY... A HIGH PRESSURE SYSTEM WILL BUILD OVER LAKE SUPERIOR BY SATURDAY MORNING. THIS HIGH WILL SLOWLY HEAD EAST SATURDAY NIGHT INTO SUNDAY AS ANOTHER TROUGH APPROACHES FROM THE NORTHERN PLAINS. WIND SPEEDS SHOULD STILL REMAIN AT OR BELOW 20 KT AS THE TROUGH SLOWLY TREKS ACROSS THE UPPER GREAT LAKES THROUGH MID WEEK. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...KC SYNOPSIS/SHORT TERM...DLG LONG TERM...ROLFSON AVIATION...KC MARINE...DLG mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 656 PM CDT SAT AUG 2 2008 .UPDATE... UPDATED FOR 00Z AVIATION DISCUSSION BELOW. && .DISCUSSION... /ISSUED AT 309 PM CDT SAT AUG 2 2008/ THE FORECAST CHALLENGES ARE AREAL COVERAGE AND TIMING OF CONVECTION AND SEVERE WEATHER POTENTIAL LATE TONIGHT THROUGH MONDAY. EARLY MORNING CLEAR SKIES AND DRY AIR ALLOWED FOR A LOW STARTING POINT TO TODAYS TEMPS...AND WITH INCOMING CIRRUS THE MERCURY HAS BEEN SOMEWHAT SLOW TO RISE THIS AFTN. BUT THE CLOUDS AND INCREASING SOUTHERLY FLOW WILL HELP TEMPS NOT TO DROP MUCH TONIGHT. LOWS IN THE UPPER 60S TO LOWER 70S SHOULD BE COMMON IN THE MN FORECAST AREA...10 TO 15 DEGREES WARMER THAN LAST NIGHT. 12Z RAOBS FROM THIS MORNING REVEALED A TIGHT 850-600MB BAROCLINIC ZONE FROM ERN SD INTO IA. THIS HAS PROPAGATED GRADUALLY NEWRD INTO SW MN AND WILL BE THE POTENTIAL BREEDING GROUND FOR SOME STRONG CONVECTION LATE TONIGHT AS LOW LEVEL JET /LLJ/ INCREASES TO 45 TO 50 KTS. SOME ACCAS WAS APPARENT THIS MORNING ON VISIBLE IN NRN IA TOO...INDICATIVE OF ELEVATED INSTABILITY. ISOLD CONVECTION HAS CONTINUED SLOWLY EWRD TODAY AHEAD OF A WEAKENING SHORTWAVE IN SD. THIS HAS BEEN UNDER VERY WARM 700MB TEMPS AS ANALYZED BY THE RUC AT 15C TO 17C. SO THERE IS A SMALL CHANCE OF SOME ISOLD SHOWERS PRIOR TO MIDNIGHT AS LLJ STRENGTHENS. MUCH BETTER POTENTIAL OVERNIGHT WITH STRONG DIFFERENTIAL THETA-E ADVECTION AND ASSOCIATED INCREASES IN INSTABILITY ACROSS SRN MN/NRN IA. STEEP MID-LEVEL LAPSE RATES AT 8-9 C/KM IN THE 700-400MB LAYER ARE PROJECTED BY THE GUIDANCE...WITH DEEP EFFECTIVE SHEAR IN THAT VERTICAL CORRIDOR. THERE IS ALSO FRONTOGENETIC FORCING AND NEGATIVE EPV FURTHER AIDING IN UPWARD MOTION. ELEVATED SUPERCELLS SEEM LIKE A POTENTIAL MODE. 09Z SREF SUPERCELL MODE PROBABILITY IS GREATER THAN 70 PERCENT IN SRN MN OVERNIGHT. FREEZING LEVEL HEIGHTS APPEAR TO BE VERY HIGH /15.5-16.0 KFT/ POSSIBLY NEGATING SVR HAIL. THIS CONVECTION IS EXPECTED TO BUILD/EVOLVE BOTH EWRD AND SWRD THRU THE REMAINDER OF SUN MORNING WITH THE ELEVATED INSTABILITY ON THE PERIPHERY OF THE CAP. SO HAVE INCREASED POPS OVERNIGHT AND SUN MORNING FOR SRN MN AND ERN MN/WRN WI RESPECTIVELY. MCS DEVELOPMENT TO OUR WEST IN ND AND POTENTIALLY SD IS NOT EXPECTED TO IMPACT THE AREA WITH PRECIP...BUT MAY LEAD TO MORE CLOUDS FOR SUN AFTN. DURING THE AFTN ON SUN...850-300MB THICKNESS RIDGE AND ASSOCIATED MID-LEVEL THERMAL RIDGE WILL BUILD INTO THE AREA. AT THE SFC...A SUB 1005MB LOW IS PROJECTED TO BE NEAR NE NEBRASKA LATE IN THE AFTN ON MODEL CONSENSUS WITH A CONNECTED 70F PLUS TD FETCH TO THE GULF. AN ASSOCIATED SFC TROUGH/SECONDARY WARM FRONT IS PROJECTED ON MOST GUIDANCE TO BE NEAR THE MN/IA BORDER. WITH SOME LOW AND MID-LEVEL CLEARING IN THE WAKE OF THE MORNING CONVECTION EXPECTED...ESPECIALLY IN SRN MN...LOW LEVEL INSTABILITY IS EXPECTED TO RAPIDLY INCREASE. HOWEVER...AFOREMENTIONED CAP LEADS TO HIGH MLCIN VALUES ON BOTH THE NAM AND GFS THROUGH 21Z AND EVEN HINTED AT UNTIL 00Z GIVEN CONVECTIVE TEMPS IN THE MID 90S LIKELY NOT BEING REACHED. HOWEVER...IN THE EVE...MID-LEVEL HEIGHTS FALLS ARE EXPECTED TO MOVE INTO THE AREA AHEAD OF A VORT MAXIMA AND CONVECTION IS THEN MUCH MORE LIKELY. WITH INCREASING LLJ SUPPORT...NAMELY IN SRN AND ERN MN AND WRN WI...SOME OF THE CONVECTION MAY VERY WELL BE STRONG TO SEVERE. MON WILL POSE ONE MORE DAY WITH CONVECTIVE POTENTIAL...AS SFC COLD FRONT OOZES SOUTHEAST THROUGH THE FORECAST AREA. OBVIOUSLY A LOT BETWEEN THEN AND NOW...BUT THE MAIN FORECAST TREND HAS BEEN TO SPEED THIS PROGRESSION UP. THIS LIKELY HAS BEEN THE CASE WITH GUIDANCE DUE TO MULTIPLE ROUNDS OF THUNDERSTORMS ON THE NORTHERN SIDE OF THE BOUNDARY. THIS SEEMS LEGIT...SO HAVE TRENDED DOWN POPS IN NRN AND WRN PORTIONS OF THE FORECAST AREA ON MON. TIMING OF IMPULSES IS NEAR IMPOSSIBLE FOR MON...BUT DOES APPEAR THERE ARE DECENT AFTN AND EVE CONVECTIVE CHANCES FOR SRN AND SE MN. FRONT LOOKS TO CLEAR THE FORECAST AREA EITHER LATE MON NIGHT OR EARLY TUES. BEYOND...NORTHWEST FLOW WILL GRADUALLY SET UP THROUGH THE END OF THE WEEK AS ERN NA LONG WAVE TROUGH REDEVELOPS. 850MB TEMPS GRADUALLY WORK DOWNWARDS AND LOW LEVEL DRIER AIR FILTERS IN. SHOULD MAKE FOR A PLEASANT END OF THE WEEK. SOME SIGNS OF VORT SPOKES DURING THU-SAT ON WRN PERIPHERY OF TROUGH...BUT AT THIS POINT THE ECMWF AND GFS WOULD FAVOR THE GREAT LAKES FOR AFTN/EVE SHRA CHANCES. && .AVIATION.../00Z TAF ISSUANCE/ DIFFICULT SET OF TAFS...WITH AREAL EXTENT OF CONVECTION UNCERTAIN ACRS THE AREA THRU TMRW AFTN/EVE. FAIRLY SUBSTANTIAL CAPPING INVERSION PRESENT ACRS MUCH OF THE AREA...WITH ANEMIC LOOKING VIS SAT IMAGE CONFIRMING SUCH. LLJ FORECAST TO INCR INTO SWRN MN...WITH RESULTING INCR IN MSTR TRANSPORT. ELEVATED TSRA/SHRA COULD DEVELOP ALNG THETA E BNDRY TOWARD EARLY MRNG /AFT 09Z/ IN SWRN MN...WHICH WOULD AFFECT RWF INITIALLY...SPREADING EWRD DURG THE MRNG HRS. WITH CONT UNCERTAINTY IN THIS SCENARIO...ELECTED TO CONT THE PROB30 AND VCSH COMBO AT ALL SITES. ADDITIONAL COMPLICATING FACTOR WRT CONVECTION IS DECRG COMPLEX NW OF THE FA. THIS COULD GRAZE AXN...AND WILL MONITOR FOR AMENDMENTS IF IT DOES NOT DIE BEFORE REACHING THE FA. DURG THE AFTN TMRW...THERE SHUD LARGELY BE DECR LO CLDS...AS DRIER AIR MOVES IN. WINDS WL REMAIN SERLY THRU THE PD. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ MTF/KAT mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 309 PM CDT SAT AUG 2 2008 .DISCUSSION... THE FORECAST CHALLENGES ARE AREAL COVERAGE AND TIMING OF CONVECTION AND SEVERE WEATHER POTENTIAL LATE TONIGHT THROUGH MONDAY. EARLY MORNING CLEAR SKIES AND DRY AIR ALLOWED FOR A LOW STARTING POINT TO TODAYS TEMPS...AND WITH INCOMING CIRRUS THE MERCURY HAS BEEN SOMEWHAT SLOW TO RISE THIS AFTN. BUT THE CLOUDS AND INCREASING SOUTHERLY FLOW WILL HELP TEMPS NOT TO DROP MUCH TONIGHT. LOWS IN THE UPPER 60S TO LOWER 70S SHOULD BE COMMON IN THE MN FORECAST AREA...10 TO 15 DEGREES WARMER THAN LAST NIGHT. 12Z RAOBS FROM THIS MORNING REVEALED A TIGHT 850-600MB BAROCLINIC ZONE FROM ERN SD INTO IA. THIS HAS PROPAGATED GRADUALLY NEWRD INTO SW MN AND WILL BE THE POTENTIAL BREEDING GROUND FOR SOME STRONG CONVECTION LATE TONIGHT AS LOW LEVEL JET /LLJ/ INCREASES TO 45 TO 50 KTS. SOME ACCAS WAS APPARENT THIS MORNING ON VISIBLE IN NRN IA TOO...INDICATIVE OF ELEVATED INSTABILITY. ISOLD CONVECTION HAS CONTINUED SLOWLY EWRD TODAY AHEAD OF A WEAKENING SHORTWAVE IN SD. THIS HAS BEEN UNDER VERY WARM 700MB TEMPS AS ANALYZED BY THE RUC AT 15C TO 17C. SO THERE IS A SMALL CHANCE OF SOME ISOLD SHOWERS PRIOR TO MIDNIGHT AS LLJ STRENGTHENS. MUCH BETTER POTENTIAL OVERNIGHT WITH STRONG DIFFERENTIAL THETA-E ADVECTION AND ASSOCIATED INCREASES IN INSTABILITY ACROSS SRN MN/NRN IA. STEEP MID-LEVEL LAPSE RATES AT 8-9 C/KM IN THE 700-400MB LAYER ARE PROJECTED BY THE GUIDANCE...WITH DEEP EFFECTIVE SHEAR IN THAT VERTICAL CORRIDOR. THERE IS ALSO FRONTOGENETIC FORCING AND NEGATIVE EPV FURTHER AIDING IN UPWARD MOTION. ELEVATED SUPERCELLS SEEM LIKE A POTENTIAL MODE. 09Z SREF SUPERCELL MODE PROBABILITY IS GREATER THAN 70 PERCENT IN SRN MN OVERNIGHT. FREEZING LEVEL HEIGHTS APPEAR TO BE VERY HIGH /15.5-16.0 KFT/ POSSIBLY NEGATING SVR HAIL. THIS CONVECTION IS EXPECTED TO BUILD/EVOLVE BOTH EWRD AND SWRD THRU THE REMAINDER OF SUN MORNING WITH THE ELEVATED INSTABILITY ON THE PERIPHERY OF THE CAP. SO HAVE INCREASED POPS OVERNIGHT AND SUN MORNING FOR SRN MN AND ERN MN/WRN WI RESPECTIVELY. MCS DEVELOPMENT TO OUR WEST IN ND AND POTENTIALLY SD IS NOT EXPECTED TO IMPACT THE AREA WITH PRECIP...BUT MAY LEAD TO MORE CLOUDS FOR SUN AFTN. DURING THE AFTN ON SUN...850-300MB THICKNESS RIDGE AND ASSOCIATED MID-LEVEL THERMAL RIDGE WILL BUILD INTO THE AREA. AT THE SFC...A SUB 1005MB LOW IS PROJECTED TO BE NEAR NE NEBRASKA LATE IN THE AFTN ON MODEL CONSENSUS WITH A CONNECTED 70F PLUS TD FETCH TO THE GULF. AN ASSOCIATED SFC TROUGH/SECONDARY WARM FRONT IS PROJECTED ON MOST GUIDANCE TO BE NEAR THE MN/IA BORDER. WITH SOME LOW AND MID-LEVEL CLEARING IN THE WAKE OF THE MORNING CONVECTION EXPECTED...ESPECIALLY IN SRN MN...LOW LEVEL INSTABILITY IS EXPECTED TO RAPIDLY INCREASE. HOWEVER...AFOREMENTIONED CAP LEADS TO HIGH MLCIN VALUES ON BOTH THE NAM AND GFS THROUGH 21Z AND EVEN HINTED AT UNTIL 00Z GIVEN CONVECTIVE TEMPS IN THE MID 90S LIKELY NOT BEING REACHED. HOWEVER...IN THE EVE...MID-LEVEL HEIGHTS FALLS ARE EXPECTED TO MOVE INTO THE AREA AHEAD OF A VORT MAXIMA AND CONVECTION IS THEN MUCH MORE LIKELY. WITH INCREASING LLJ SUPPORT...NAMELY IN SRN AND ERN MN AND WRN WI...SOME OF THE CONVECTION MAY VERY WELL BE STRONG TO SEVERE. MON WILL POSE ONE MORE DAY WITH CONVECTIVE POTENTIAL...AS SFC COLD FRONT OOZES SOUTHEAST THROUGH THE FORECAST AREA. OBVIOUSLY A LOT BETWEEN THEN AND NOW...BUT THE MAIN FORECAST TREND HAS BEEN TO SPEED THIS PROGRESSION UP. THIS LIKELY HAS BEEN THE CASE WITH GUIDANCE DUE TO MULTIPLE ROUNDS OF THUNDERSTORMS ON THE NORTHERN SIDE OF THE BOUNDARY. THIS SEEMS LEGIT...SO HAVE TRENDED DOWN POPS IN NRN AND WRN PORTIONS OF THE FORECAST AREA ON MON. TIMING OF IMPULSES IS NEAR IMPOSSIBLE FOR MON...BUT DOES APPEAR THERE ARE DECENT AFTN AND EVE CONVECTIVE CHANCES FOR SRN AND SE MN. FRONT LOOKS TO CLEAR THE FORECAST AREA EITHER LATE MON NIGHT OR EARLY TUES. BEYOND...NORTHWEST FLOW WILL GRADUALLY SET UP THROUGH THE END OF THE WEEK AS ERN NA LONG WAVE TROUGH REDEVELOPS. 850MB TEMPS GRADUALLY WORK DOWNWARDS AND LOW LEVEL DRIER AIR FILTERS IN. SHOULD MAKE FOR A PLEASANT END OF THE WEEK. SOME SIGNS OF VORT SPOKES DURING THU-SAT ON WRN PERIPHERY OF TROUGH...BUT AT THIS POINT THE ECMWF AND GFS WOULD FAVOR THE GREAT LAKES FOR AFTN/EVE SHRA CHANCES. && .AVIATION... /18Z TAF ISSUANCE/ HIGH PRESSURE CENTERED OVER NORTHERN WI AT MIDDAY. SE SURFACE WINDS BEGINNING TO INCREASE ON THE BACKSIDE OF THE HIGH ACROSS CENTRAL AND WESTERN MN. EXPECT 12 TO 15 KNOT WINDS DEVELOPING DURING THE MID TO LATE AFTERNOON FOR THE MN TAF SITES WITH GUSTS INTO THE MID 20S FOR KAXN AND KRWF. DEVELOPING WARM FRONT ACROSS EASTERN SD AND WESTERN IA WILL SLOWLY MOVE OUR WAY TONIGHT. LOW LEVEL JET POKING INTO FAR SOUTHERN MN OVERNIGHT. THIS COMBINED WITH LOW LEVEL WAA AND STRONG 850 MB MOISTURE TRANSPORT SHOULD PROMOTE THUNDERSTORMS TO CONTINUE TO DEVELOP/PROPAGATE FROM EASTERN SD INTO WEST CENTRAL AND SOUTHWEST MN BY LATE IN THE EVENING AND PERHAPS REACH THE TWIN CITIES AROUND DAYBREAK. HAVE INDICATED PROB GROUPS FOR THUNDER FOR ALL BUT KEAU OVERNIGHT/EARLY SUNDAY. IF ACTIVITY FORMS AS EXPECTED...KEAU MAY SEE SOME SHOWERS AND THUNDERSTORMS JUST BEYOND THE END OF THE TAF PERIOD. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ MTF/RAH mn AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GREAT FALLS MT 1035 PM MDT FRI AUG 1 2008 UPDATED AVIATION SECTION .DISCUSSION... A SURFACE COLD FRONT HAS MOVED ACROSS SOUTHWARD ACROSS THE NORTHERN HALF OF THE FORECAST AREA...WITH NORTHWESTERLY WINDS BEHIND THE COLD FRONT. SURFACE CONVERGENCE ALONG THE FRONT COMBINED WITH SOME MID-LEVEL MOISTURE AND WEAK MID-LEVEL LIFT HAS RESULTED IN ISOLATED SHOWERS AND THUNDERSTORMS DEVELOPING OVER SOUTHWEST AND SOUTHERN PORTIONS OF CENTRAL MONTANA. DEEP MIXING COMBINED WITH VERY DRY LOW LEVELS HAS RESULTED IN WIND GUSTS OVER 50 MPH WITH SOME OF THE SHOWERS AND STORMS. THE RUC IS HINTING AT ISOLATED PRECIP THROUGH MIDNIGHT FROM MADISON COUNTY THROUGH FERGUS COUNTY...CONSISTENT WITH CURRENT RADAR IMAGERY. THUS ISOLATED POP COVERAGE HAS BEEN EXPANDED NORTHWESTWARD. AFTER MIDNIGHT...LOW LEVEL STABILIZATION WILL SIGNIFICANTLY REDUCE PRECIP CHANCES...THOUGH AN ISOLATED SHOWER OR STORM CANNOT BE COMPLETELY RULED OUT FROM LEWISTOWN TO BOZEMAN...WHERE ADDITIONAL LIFT IS FORECAST. CLOUD COVERAGE HAS ALSO BEEN INCREASED OVER SOUTHWEST MONTANA PER LATEST VISIBLE SATELLITE IMAGERY. TEMPERATURE AND WIND FORECASTS ARE IN GOOD SHAPE. NO OTHER SIGNIFICANT CHANGES MADE. FOR SATURDAY...A WEAK COLD FRONT WILL SLIDE SOUTHWARD ACROSS THE REGION. INSTABILITY AHEAD OF THE COLD FRONT IS FORECAST TO BE STRONGER THAN THAT TODAY...WITH STRONG VERTICAL WIND SHEAR PERSISTING. A SHORTWAVE TROUGH PROPAGATING THROUGH SOUTHWESTERLY FLOW ALOFT IN CONJUNCTION WITH THE LARGE SCALE UPPER LEVEL TROUGH OVER ALBERTA WILL FURTHER AID IN THE THREAT FOR STRONG TO SEVERE THUNDERSTORMS OVER CENTRAL AND SOUTHWEST MONTANA SATURDAY AFTERNOON AND EVENING...WITH THE PRIMARY THREAT BEING STRONG WINDS. COHEN && .AVIATION... UPDATED 0435Z. A SURFACE COLD FRONT CONTINUES TO SLOWLY MOVE SOUTH AND EAST ACROSS THE AREA TONIGHT. WINDS HAVE DECREASED IN SPEED AND BECOME NORTHWESTERLY. ISOLATED THUNDERSTORMS HAVE DEVELOPED...MAINLY EAST OF A GREAT FALLS TO HAVRE LINE... AND WILL CONTINUE BEFORE ENDING BY 08Z. VFR CONDITIONS PREVAIL WITH MVFR CONDITIONS LIKELY IN THE VICINITY OF THUNDERSTORMS. && .FIRE WEATHER... UPDATED 0330Z. SURFACE WIND SPEEDS WILL CONTINUE TO DECREASE THIS EVENING ACROSS NORTH CENTRAL...CENTRAL...AND SOUTHWEST MONTANA...AS RELATIVE HUMIDITIES CONTINUE TO RISE. BETTER RELATIVE HUMIDITY RECOVERY IS EXPECTED TONIGHT THAN LAST NIGHT...WITH MAXIMUM RELATIVE HUMIDITIES FORECAST TO BE IN THE 60 TO 70 PERCENT RANGE TONIGHT. THUS...THE RED FLAG WARNING FOR THIS EVENING HAS BEEN ALLOWED TO EXPIRE. ISOLATED SHOWERS AND THUNDERSTORMS OVER SOUTHWEST AND CENTRAL MONTANA ARE EXPECTED TO PERSIST THROUGH MIDNIGHT...AND THEN DIMINISH THEREAFTER. THESE SHOWERS AND STORMS WILL BE CAPABLE OF PRODUCING LITTLE RAINFALL ALONG WITH GUSTY AND ERRATIC WINDS. FOR SATURDAY AND SUNDAY...BREEZY WINDS ARE EXPECTED IN THE AFTERNOON AND EVENING...THOUGH THE WINDS SHOULD NOT BE AS STRONG AS THEY WERE TODAY. RELATIVE HUMIDITIES WILL BE HIGHER AS WELL...SO THE THREAT FOR HAZARDOUS FIRE WEATHER CONDITIONS WILL BE LOWER THIS WEEKEND. ISOLATED SHOWERS AND THUNDERSTORMS IN THE AFTERNOONS AND EVENINGS THIS WEEKEND COULD RESULT IN GUSTY AND ERRATIC SURFACE WINDS. ACOHEN && .PREV DISCUSSION... /ISSUED 540 PM MDT FRI AUG 1 2008/ TONIGHT THROUGH SUNDAY...A STRONG SOUTHWEST FLOW ALOFT WILL CONTINUE OVER NORTH CENTRAL...CENTRAL...AND SOUTHWEST MONTANA TONIGHT AHEAD OF AN UPPER LEVEL TROUGH. WITH A VERY WARM AND UNSTABLE AIRMASS IN PLACE AHEAD OF A COLD FRONT...A FEW DISTURBANCES IN THE FLOW WILL BRING ISOLATED THUNDERSTORMS WITH GUSTY WINDS TO SOUTHWEST AND CENTRAL MONTANA. OTHERWISE...THE STRONG SOUTHWEST WINDS WILL ALSO CONTINUE TO MIX DOWN TO THE SURFACE ACROSS THE AREA...ESPECIALLY OVER THE PLAINS OF NORTH CENTRAL MONTANA WHERE WIDESPREAD WIND GUSTS OF 35 TO 45 MPH WILL PERSIST INTO THE EVENING. IT WILL ALSO REMAIN QUITE DRY...WITH RELATIVE HUMIDITIES STAYING BELOW 20 PERCENT IN THE EVENING. A RED FLAG WARNING WILL REMAIN IN EFFECT UNTIL 9 PM MDT ACROSS THE ENTIRE AREA (SEE FIRE WEATHER DISCUSSION). AS THE COLD FRONT PUSHES THROUGH THE AREA THIS EVENING...WINDS WILL SHIFT MORE NORTHWESTERLY AND DECREASE AND TEMPERATURES WILL GRADUALLY COOL TO NEAR NORMAL OVERNIGHT. A SLIGHTLY MORE MOIST AND WESTERLY FLOW ALOFT WILL LINGER OVER THE AREA SATURDAY THROUGH SUNDAY. GUSTY WESTERLY WINDS WILL MIX DOWN TO THE SURFACE DURING THE AFTERNOON AND EVENING HOURS...BUT THEY WILL NOT BE AS STRONG AS THOSE TODAY. ALTHOUGH TEMPERATURES WILL ALSO BE COOLER THAN THEY ARE TODAY...THEY WILL STILL WARM TO NEAR NORMAL LEVELS AND THE AIRMASS WILL BECOME MARGINALLY UNSTABLE. THIS WILL ALLOW FOR A SLIGHT CHANCE OF THUNDERSTORMS TO DEVELOP OVER THE HIGHER TERRAIN DURING THE AFTERNOON AND EVENING. COULSTON SUNDAY NIGHT THROUGH FRIDAY...AN UPPER LEVEL LOW PRESSURE TROUGH WILL MOVE THROUGH THE CWA SUNDAY NIGHT AND MONDAY PRODUCING A FEW ISOLATED THUNDERSTORMS. SLIGHTLY COOLER AIR WILL MOVE IN BEHIND THE TROUGH MONDAY WITH AFTERNOON HIGHS EXPECTED TO BE A FEW DEGREES BELOW NORMAL FOR MOST LOCATIONS. HIGH PRESSURE BEGINS TO REBUILD IN FROM THE WEST TUESDAY...WITH THE RIDGE CENTERING OVER THE CWA WEDNESDAY AND SLOWLY WORKING INTO EASTERN MONTANA BY FRIDAY. CHANCES FOR PRECIPITATION WILL GENERALLY BE LESS THAN 20 PERCENT AS A RESULT. THERE COULD BE SOME ISOLATED...MAINLY DRY...THUNDERSTORMS DURING THE LATE AFTERNOON AND EARLY EVENING HOURS. TEMPERATURES WILL WARM TO A FEW DEGREES ABOVE SEASONAL NORMALS UNDER THE INFLUENCE OF THE RIDGE TUESDAY THROUGH THURSDAY. && .PRELIMINARY POINT TEMPS/POPS... GTF 50 83 47 82 / 10 20 20 10 CTB 46 78 42 77 / 10 10 10 10 HLN 55 86 54 84 / 10 20 20 10 BZN 50 88 48 84 / 20 20 20 20 WEY 43 80 41 78 / 20 20 20 20 DLN 49 85 47 82 / 10 20 20 20 HVR 50 85 46 83 / 10 10 20 10 LWT 50 83 48 79 / 20 20 20 10 && .TFX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...COHEN SHORT TERM...COULSTON LONG TERM...LOSS AVIATION...EMANUEL WEATHER.GOV/GREATFALLS mt AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GREAT FALLS MT 920 PM MDT FRI AUG 1 2008 .UPDATE... A SURFACE COLD FRONT HAS MOVED ACROSS SOUTHWARD ACROSS THE NORTHERN HALF OF THE FORECAST AREA...WITH NORTHWESTERLY WINDS BEHIND THE COLD FRONT. SURFACE CONVERGENCE ALONG THE FRONT COMBINED WITH SOME MID-LEVEL MOISTURE AND WEAK MID-LEVEL LIFT HAS RESULTED IN ISOLATED SHOWERS AND THUNDERSTORMS DEVELOPING OVER SOUTHWEST AND SOUTHERN PORTIONS OF CENTRAL MONTANA. DEEP MIXING COMBINED WITH VERY DRY LOW LEVELS HAS RESULTED IN WIND GUSTS OVER 50 MPH WITH SOME OF THE SHOWERS AND STORMS. THE RUC IS HINTING AT ISOLATED PRECIP THROUGH MIDNIGHT FROM MADISON COUNTY THROUGH FERGUS COUNTY...CONSISTENT WITH CURRENT RADAR IMAGERY. THUS ISOLATED POP COVERAGE HAS BEEN EXPANDED NORTHWESTWARD. AFTER MIDNIGHT...LOW LEVEL STABILIZATION WILL SIGNIFICANTLY REDUCE PRECIP CHANCES...THOUGH AN ISOLATED SHOWER OR STORM CANNOT BE COMPLETELY RULED OUT FROM LEWISTOWN TO BOZEMAN...WHERE ADDITIONAL LIFT IS FORECAST. CLOUD COVERAGE HAS ALSO BEEN INCREASED OVER SOUTHWEST MONTANA PER LATEST VISIBLE SATELLITE IMAGERY. TEMPERATURE AND WIND FORECASTS ARE IN GOOD SHAPE. NO OTHER SIGNIFICANT CHANGES MADE. FOR SATURDAY...A WEAK COLD FRONT WILL SLIDE SOUTHWARD ACROSS THE REGION. INSTABILITY AHEAD OF THE COLD FRONT IS FORECAST TO BE STRONGER THAN THAT TODAY...WITH STRONG VERTICAL WIND SHEAR PERSISTING. A SHORTWAVE TROUGH PROPAGATING THROUGH SOUTHWESTERLY FLOW ALOFT IN CONJUNCTION WITH THE LARGE SCALE UPPER LEVEL TROUGH OVER ALBERTA WILL FURTHER AID IN THE THREAT FOR STRONG TO SEVERE THUNDERSTORMS OVER CENTRAL AND SOUTHWEST MONTANA SATURDAY AFTERNOON AND EVENING...WITH THE PRIMARY THREAT BEING STRONG WINDS. COHEN && .AVIATION... UPDATED 2340Z. A SURFACE COLD FRONT WILL MOVE ACROSS THE AREA THIS EVENING. WEST WINDS WILL REMAIN GUSTY AHEAD OF THE FRONT WITH WINDS SLOWLY DIMINISHING AND BECOMING NORTHWESTERLY AFTER 04Z. ISOLATED EVENING THUNDERSTORMS ARE POSSIBLE...MAINLY SOUTH OF A LINE FROM DILLON TO BOZEMAN TO LEWISTOWN. CONVECTIVE ACTIVITY WILL END BY 06Z. VFR CONDITIONS PREVAIL WITH MVFR CONDITIONS POSSIBLE IN THE VICINITY OF THUNDERSTORMS. && .FIRE WEATHER... UPDATED 0330Z. SURFACE WIND SPEEDS WILL CONTINUE TO DECREASE THIS EVENING ACROSS NORTH CENTRAL...CENTRAL...AND SOUTHWEST MONTANA...AS RELATIVE HUMIDITIES CONTINUE TO RISE. BETTER RELATIVE HUMIDITY RECOVERY IS EXPECTED TONIGHT THAN LAST NIGHT...WITH MAXIMUM RELATIVE HUMIDITIES FORECAST TO BE IN THE 60 TO 70 PERCENT RANGE TONIGHT. THUS...THE RED FLAG WARNING FOR THIS EVENING HAS BEEN ALLOWED TO EXPIRE. ISOLATED SHOWERS AND THUNDERSTORMS OVER SOUTHWEST AND CENTRAL MONTANA ARE EXPECTED TO PERSIST THROUGH MIDNIGHT...AND THEN DIMINISH THEREAFTER. THESE SHOWERS AND STORMS WILL BE CAPABLE OF PRODUCING LITTLE RAINFALL ALONG WITH GUSTY AND ERRATIC WINDS. FOR SATURDAY AND SUNDAY...BREEZY WINDS ARE EXPECTED IN THE AFTERNOON AND EVENING...THOUGH THE WINDS SHOULD NOT BE AS STRONG AS THEY WERE TODAY. RELATIVE HUMIDITIES WILL BE HIGHER AS WELL...SO THE THREAT FOR HAZARDOUS FIRE WEATHER CONDITIONS WILL BE LOWER THIS WEEKEND. ISOLATED SHOWERS AND THUNDERSTORMS IN THE AFTERNOONS AND EVENINGS THIS WEEKEND COULD RESULT IN GUSTY AND ERRATIC SURFACE WINDS. ACOHEN && .PREV DISCUSSION... /ISSUED 540 PM MDT FRI AUG 1 2008/ TONIGHT THROUGH SUNDAY...A STRONG SOUTHWEST FLOW ALOFT WILL CONTINUE OVER NORTH CENTRAL...CENTRAL...AND SOUTHWEST MONTANA TONIGHT AHEAD OF AN UPPER LEVEL TROUGH. WITH A VERY WARM AND UNSTABLE AIRMASS IN PLACE AHEAD OF A COLD FRONT...A FEW DISTURBANCES IN THE FLOW WILL BRING ISOLATED THUNDERSTORMS WITH GUSTY WINDS TO SOUTHWEST AND CENTRAL MONTANA. OTHERWISE...THE STRONG SOUTHWEST WINDS WILL ALSO CONTINUE TO MIX DOWN TO THE SURFACE ACROSS THE AREA...ESPECIALLY OVER THE PLAINS OF NORTH CENTRAL MONTANA WHERE WIDESPREAD WIND GUSTS OF 35 TO 45 MPH WILL PERSIST INTO THE EVENING. IT WILL ALSO REMAIN QUITE DRY...WITH RELATIVE HUMIDITIES STAYING BELOW 20 PERCENT IN THE EVENING. A RED FLAG WARNING WILL REMAIN IN EFFECT UNTIL 9 PM MDT ACROSS THE ENTIRE AREA (SEE FIRE WEATHER DISCUSSION). AS THE COLD FRONT PUSHES THROUGH THE AREA THIS EVENING...WINDS WILL SHIFT MORE NORTHWESTERLY AND DECREASE AND TEMPERATURES WILL GRADUALLY COOL TO NEAR NORMAL OVERNIGHT. A SLIGHTLY MORE MOIST AND WESTERLY FLOW ALOFT WILL LINGER OVER THE AREA SATURDAY THROUGH SUNDAY. GUSTY WESTERLY WINDS WILL MIX DOWN TO THE SURFACE DURING THE AFTERNOON AND EVENING HOURS...BUT THEY WILL NOT BE AS STRONG AS THOSE TODAY. ALTHOUGH TEMPERATURES WILL ALSO BE COOLER THAN THEY ARE TODAY...THEY WILL STILL WARM TO NEAR NORMAL LEVELS AND THE AIRMASS WILL BECOME MARGINALLY UNSTABLE. THIS WILL ALLOW FOR A SLIGHT CHANCE OF THUNDERSTORMS TO DEVELOP OVER THE HIGHER TERRAIN DURING THE AFTERNOON AND EVENING. COULSTON SUNDAY NIGHT THROUGH FRIDAY...AN UPPER LEVEL LOW PRESSURE TROUGH WILL MOVE THROUGH THE CWA SUNDAY NIGHT AND MONDAY PRODUCING A FEW ISOLATED THUNDERSTORMS. SLIGHTLY COOLER AIR WILL MOVE IN BEHIND THE TROUGH MONDAY WITH AFTERNOON HIGHS EXPECTED TO BE A FEW DEGREES BELOW NORMAL FOR MOST LOCATIONS. HIGH PRESSURE BEGINS TO REBUILD IN FROM THE WEST TUESDAY...WITH THE RIDGE CENTERING OVER THE CWA WEDNESDAY AND SLOWLY WORKING INTO EASTERN MONTANA BY FRIDAY. CHANCES FOR PRECIPITATION WILL GENERALLY BE LESS THAN 20 PERCENT AS A RESULT. THERE COULD BE SOME ISOLATED...MAINLY DRY...THUNDERSTORMS DURING THE LATE AFTERNOON AND EARLY EVENING HOURS. TEMPERATURES WILL WARM TO A FEW DEGREES ABOVE SEASONAL NORMALS UNDER THE INFLUENCE OF THE RIDGE TUESDAY THROUGH THURSDAY. && .PRELIMINARY POINT TEMPS/POPS... GTF 50 83 47 82 / 10 20 20 10 CTB 46 78 42 77 / 10 10 10 10 HLN 55 86 54 84 / 10 20 20 10 BZN 50 88 48 84 / 20 20 20 20 WEY 43 80 41 78 / 20 20 20 20 DLN 49 85 47 82 / 10 20 20 20 HVR 50 85 46 83 / 10 10 20 10 LWT 50 83 48 79 / 20 20 20 10 && .TFX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...COHEN SHORT TERM...COULSTON LONG TERM...LOSS AVIATION...EMANUEL WEATHER.GOV/GREATFALLS mt AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GREAT FALLS MT 1050 PM MDT THU JUL 31 2008 ...UPDATE TO AVIATION... .UPDATE... GOING FORECAST FOR TONIGHT IS IN GOOD SHAPE. THE ONLY CHANGE MADE FOR OVERNIGHT FORECAST WAS TO UPDATE HOURLY TEMPERATURE/DEWPOINT/RELATIVE HUMIDITY GRIDS PER RECENT OBSERVATIONS. EARLY EVENING SURFACE ANALYSIS PLACES A WEAK SURFACE RIDGE OVER EASTERN MONTANA...WITH VERY LOW DEWPOINTS / 15F TO 25F RANGE / OVER THE FORECAST AREA. DEEP MIXING IN THE PRESENCE OF STRONG WINDS ALOFT / 25 TO 35 KTS PER 00Z SOUNDING AT GTF / WERE RESULTING IN GUSTY SURFACE WINDS THROUGH THE DAY...AS WELL AS HAZARDOUS FIRE WEATHER CONDITIONS WITH THE LOW RELATIVE HUMIDITIES. THROUGH THE NIGHT...AS THE MIXED LAYER BECOMES SHALLOWER...EXPECT SURFACE WIND SPEEDS TO BECOME LIGHTER AND MORE SOUTHWESTERLY AS A SURFACE TROUGH DEVELOPS OVER EASTERN MONTANA. A VERY WINDY DAY IS ANTICIPATED FOR FRIDAY...AS THE SURFACE PRESSURE GRADIENT TIGHTENS OVER THE FORECAST AREA IN RESPONSE TO DEEPENING OF A SURFACE LOW DUE TO (1) INTENSE HEATING OVER SOUTHEAST MONTANA AND (2) ASCENT DOWNSTREAM OF AN APPROACHING DRY PACIFIC TROUGH FURTHER ENHANCED BY A SERIES OF SHORTWAVE TROUGHS EJECTED FROM THE PRIMARY TROUGH. THE SURFACE PRESSURE GRADIENT WILL BE PARTICULARLY STRONG OVER CENTRAL MONTANA IN THE AFTERNOON...WITH GUSTY WESTERLY DOWNSLOPE WINDS TO FURTHER AID IN LOW RELATIVE HUMIDITIES. THE FIRE WEATHER WATCH FOR FRIDAY HAS BEEN UPGRADED TO A RED FLAG WARNING. PLEASE SEE THE FIRE WEATHER DISCUSSION BELOW FOR DETAILS. THE OTHER CHANGE TO THE FORECAST PACKAGE HAS BEEN THE ISSUANCE OF A HIGH WIND WATCH FOR FRIDAY LATE MORNING AND AFTERNOON FOR THE NORTHERN ROCKY MOUNTAIN FRONT. FORECAST MODELS CONTINUE TO SHOW AN INCREASE IN THE STRENGTH OF THE MIDDLE AND UPPER LEVEL FLOW FOR FRIDAY AFTERNOON...AS AN UPPER LEVEL PACIFIC TROUGH IS FORECAST TO APPROACH THE NORTHWEST CONUS. A 300 MB JET CORE OF 95 KTS IS FORECAST TO MOVE ALONG A SOUTHWEST-NORTHEAST TRAJECTORY ACROSS SOUTHERN BRITISH COLUMBIA AND SOUTHERN ALBERTA...WITH 75 TO 85 KTS OF 300 MB FLOW DEPICTED FOR THE NORTHERN ROCKY MOUNTAIN FRONT. INTERESTINGLY...THE 500 MB JET MAX IS FORECAST TO BE CENTERED RIGHT OVER THE NORTHERN ROCKY MOUNTAIN FRONT...WITH 60 TO 65 KTS FORECAST PER THE NAM AND GFS. COMPARING THE POTENTIAL WIND EVENT ON FRIDAY WITH THAT YESTERDAY (WEDNESDAY)...RUC ANALYSIS WAS SHOWING 45 TO 50 KTS AT 500 MB WHEN SURFACE WINDS WERE MEASURED AROUND 50 KTS WEDNESDAY AFTERNOON OVER THE NORTHERN ROCKY MOUNTAIN FRONT...ALONG WITH LOW LEVEL COLD FRONT PASSAGE IN THE MORNING. WINDS AT 700 MB PER RUC ANALYSIS FOR WEDNESDAY WERE INDICATED AT 25 TO 35 KTS...WHILE FORECAST NAM/GFS/ECMWF WINDS AT 700 MB FOR FRIDAY ARE AT 40 TO 50 KTS. FOR FRIDAY...ANOTHER COLD FRONT IS FORECAST TO MOVE ACROSS THE NORTHERN ROCKY MOUNTAIN FRONT BY LATE MORNING...WITH LOW LEVEL COLD AIR ADVECTION BEHIND THE FRONT LIKELY FORCING HIGH MOMENTUM AIR ALOFT TO THE SURFACE. WHILE FORECAST SOUNDINGS NEAR GLACIER NATIONAL PARK DO NOT SHOW ANY STRONG STABLE LAYERS ALOFT FOR FRIDAY AFTERNOON TO ENHANCE MOUNTAIN WAVE PROPAGATION...SINKING MOTION BEHIND THE COLD FRONT WILL CERTAINLY AID IN TRANSFERRING STRONG WINDS ALOFT TO THE SURFACE. WHILE MIXING WILL BE REDUCED SOMEWHAT IN THE AFTERNOON WELL BEHIND THE COLD FRONT...MODELS SHOW A SERIES OF WEAK VORTICITY MAXIMA PROPAGATING THROUGH SOUTHWESTERLY FLOW ALOFT TO ENHANCE MIXING SOMEWHAT...MAINTAINING THE HIGH WIND THREAT INTO THE AFTERNOON. THUS...WITH STRONGER FLOW EXPECTED FRIDAY THAN WEDNESDAY...AND WITH A SIMILAR GEOMETRY IN THE UPPER LEVEL FLOW PATTERN...ENOUGH CONFIDENCE IS IN PLACE FOR A HIGH WIND WATCH TO HAVE BEEN HOISTED FOR THE NORTHERN ROCKY MOUNTAIN FRONT 9 AM TO 6 PM MDT FRIDAY. FORECAST SURFACE WIND SPEEDS HAVE ALSO BEEN INCREASED FOR THE NORTHERN ROCKY MOUNTAIN FRONT FOR FRIDAY. ACOHEN && .AVIATION... UPDATED 0450Z. VFR CONDITIONS WILL PREVAIL OVER NORTH CENTRAL AND SOUTHWEST MONTANA. INCREASING CLOUDINESS EXPECTED ABOVE 25000 FT AGL IN THE SOUTH TONIGHT AND FRIDAY MORNING. WINDS WILL INCREASE LATE FRIDAY MORNING THROUGH FRIDAY AFTERNOON WITH WESTERLY WINDS OF NEAR 30 KNOTS...GUSTS NEAR 40 KNOTS NEAR KCTB...AND GUSTS NEAR 65 KNOTS ALONG THE NORTHERN ROCKY MOUNTAIN FRONT. ISOLATED THUNDERSTORMS ARE POSSIBLE SOUTHWEST AND CENTRAL IN VICINITY OF KBZN AND KLWT. WINDS AND THUNDERSTORMS WILL DECREASE AFTER 02Z. && .FIRE WEATHER... UPDATED 0325Z. WEST AND SOUTHWEST SURFACE WINDS WILL CONTINUE TO DECREASE IN SPEED THIS EVENING ACROSS NORTH CENTRAL...CENTRAL...AND SOUTHWEST MONTANA...AS RELATIVE HUMIDITIES CONTINUE TO RISE. HOWEVER...RELATIVE HUMIDITY RECOVERY TONIGHT WILL BE POOR...WITH MAXIMUM RELATIVE HUMIDITIES FORECAST TO BE IN THE 45 TO 55 PERCENT RANGE. THE RED FLAG WARNING FOR THIS EVENING HAS BEEN ALLOWED TO EXPIRE. RELATIVE HUMIDITIES WILL FALL INTO THE 15 TO 25 PERCENT RANGE OVER MUCH OF THE REGION ON FRIDAY...WITH STRONG AND GUSTY SURFACE WINDS FOR MUCH OF THE DAY...ESPECIALLY WHEN A COLD FRONT MOVES ACROSS THE REGION MID-DAY. THUS...THE FIRE WEATHER WATCH HAS BEEN UPGRADED TO A RED FLAG WARNING FOR ALL FIRE WEATHER ZONES. ALSO...ISOLATED THUNDERSTORMS...CAPABLE OF PRODUCING LITTLE PRECIPITATION AND GUSTY AND ERRATIC WINDS...WILL BE POSSIBLE SATURDAY AFTERNOON. ACOHEN && .PREV DISCUSSION... /ISSUED 545 PM MDT THU JUL 31 2008/ TONIGHT THROUGH SATURDAY...AN UPPER LEVEL RIDGE WILL REMAIN OVER NORTH CENTRAL...CENTRAL...AND SOUTHWEST MONTANA OVERNIGHT. THIS WILL KEEP THE AREA DRY WITH OVERNIGHT LOWS REMAINING NEAR TO SLIGHTLY ABOVE SEASONAL AVERAGES. BREEZY AND GUSTY WESTERLY WINDS MIXING DOWN FROM ALOFT WILL DECREASE OVERNIGHT AS WELL. ON FRIDAY...THE FLOW ALOFT WILL INCREASE AND BECOME MORE SOUTHWESTERLY AS AN UPPER LEVEL TROUGH MOVES INTO THE PACIFIC NORTHWEST. TEMPERATURES WILL ALSO WARM WELL ABOVE NORMAL AS AN INVERTED SURFACE TROUGH DEVELOPS OVER THE AREA WITH AN ASSOCIATED THERMAL RIDGE. THE WARMER TEMPERATURES WILL CAUSE THE WINDS ALOFT TO MIX DOWN TO THE SURFACE...WITH WINDS BECOMING QUITE STRONG ALONG THE ROCKY MOUNTAIN FRONT. WILL CONTINUE TO MONITOR WHETHER A HIGH WIND WATCH MAY BE NEEDED THERE. THE DRY AND BREEZY CONDITIONS BOTH THIS EVENING AND ON FRIDAY WARRANT FIRE WEATHER HIGHLIGHTS...AND THESE CONCERNS WILL BE ADDRESSED IN THE FIRE WEATHER SECTION BELOW. MOISTURE ALOFT WILL INCREASE SOMEWHAT WITH THE SOUTHWEST FLOW WITH INCREASING INSTABILITY...WHICH WILL BRING A SLIGHT CHANCE OF THUNDERSTORMS WITH GUSTY WINDS TO SOUTHWEST AND SOUTH CENTRAL MONTANA. THE PACIFIC NORTHWEST TROUGH WILL THEN APPROACH MONTANA FROM THE WEST FRIDAY NIGHT INTO SATURDAY...USHERING IN SLIGHTLY COOLER AIR AND CONTINUING THE INCREASINGLY MOIST SOUTHWEST FLOW ALOFT. THE AIRMASS WILL BECOME UNSTABLE AGAIN ON SATURDAY...WHICH WILL BRING A SLIGHT CHANCE OF AFTERNOON THUNDERSTORMS TO MOST OF THE AREA. BREEZY WESTERLY WINDS WILL DEVELOP AGAIN ON SATURDAY...BUT THEY WILL NOT BE QUITE AS STRONG AS ON FRIDAY. COULSTON SATURDAY NIGHT THROUGH TUESDAY NIGHT...AN UPPER LEVEL TROF OF LOW PRESSURE WILL BE MOVING INTO THE PACIFIC NORTHWEST EARLY IN THE PERIOD...THEN SLOWLY MOVE TOWARDS WESTERN MONTANA FOR SUNDAY AND MONDAY. AS A RESULT...A SOUTHWESTERLY FLOW ALOFT WILL DEVELOP OVER CENTRAL MONTANA. THIS MEANS ABOVE NORMAL TEMPERATURES AND SMALL CHANCES FOR ISOLATED THUNDERSTORMS ACROSS THE REGION. AFTERNOON HIGHS WILL GENERALLY AVERAGE AROUND 5 DEGREES ABOVE NORMAL FOR SUNDAY AND MONDAY. THE BEST CHANCE FOR ANY THUNDERSTORMS WILL BE DURING THE AFTERNOON AND EVENING HOURS...BUT AGAIN ANY THUNDERSTORM ACTIVITY SHOULD BE ISOLATED. BRUSDA WEDNESDAY AND THURSDAY...AN UPPER LEVEL RIDGE WILL CONTINUE TO TO INFLUENCE OUR WEATHER WITH ABOVE SEASONAL AVERAGE TEMPERATURES ALONG WITH LITTLE OR NO PRECIPITATION. A FEW WEAK UPPER LEVEL DISTURBANCE MAY MOVE THROUGH THE RIDGE AT TIMES FOR ONLY A SLIGHT CHANCE OF AFTERNOON THROUGH EARLY NIGHTTIME THUNDERSTORMS OVER THE MOUNTAINS. WILLIAMSON DC && .PRELIMINARY POINT TEMPS/POPS... GTF 86 53 91 52 / 0 0 0 0 CTB 79 48 82 48 / 0 0 10 0 HLN 89 56 93 58 / 0 0 0 0 BZN 91 51 96 52 / 0 0 10 10 WEY 80 47 84 47 / 0 0 10 10 DLN 81 51 89 51 / 0 0 10 0 HVR 85 50 93 53 / 0 0 0 10 LWT 83 50 91 52 / 0 0 10 10 && .TFX WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING FROM NOON TO 9 PM MDT FRIDAY FOR MTZ112>118. HIGH WIND WATCH FROM 9 AM MDT FRIDAY THROUGH FRIDAY AFTERNOON FOR MTZ009. && $$ UPDATE...COHEN SHORT TERM...COULSTON LONG TERM...BRUSDA/WILLIAMSON DC AVIATION...LOSS WEATHER.GOV/GREATFALLS mt AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 229 PM EDT SAT AUG 2 2008 .SYNOPSIS... A LOW PRESSURE SYSTEM AND COLD FRONT WILL MOVE THROUGH THE AREA TODAY AND TRIGGER SHOWERS AND THUNDERSTORMS. SOMEWHAT DRIER AIR WILL MOVE INTO THE AREA LATER TODAY AND SUNDAY, ALTHOUGH SCATTERED SHOWERS ARE STILL POSSIBLE INTO SUNDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 1215AM...UPDATE TO REMOVE MORNING CAT POPS AND FOCUS ON SCT AFTERNOON CONVECTION THAT IS STARTING TO DEVELOP OVER CNY AS BREAKING CLOUDS ALLOWS THE LLEVELS TO WARM WHILE STRONG PVA ALONG WITH HEIGHT/TEMPERATURE FALLS ALOFT DESTABILIZE THE COLUMN. LAST PLACE TO DESTABILIZE WILL BE NE PA WHERE CLOUDS HAVE HELD ON THE LONGEST...BUT EVEN HERE...SCT ACTIVITY LOOKS LIKE A GOOD BET BY MID AFTERNOON. HAVE ALSO LOWERED TEMPS A TAD BASED ON CURRENT TRENDS. NEW GRIDS/PRODUCTS ARE OUT. AS OF 915AM...SHRA AND EMBEDDED TSRA ARE CROSSING THE CWA ATTM AS VORT MAX CURRENTLY OVER LAKE ERIE DIGS INTO THE BASE OF THE DEVELOPING NE CONUS TROUGH...CAUSING IT TO DEVELOP MORE OF A NEUTRAL TILT THIS MORNING...WITH GOOD PVA/QVEC CONVERGENCE OVERHEAD. CLEARING IS ALREADY BEGINNING TO PUSH INTO THE WESTERN ZONES BEHIND THIS FIRST AREA OF SHRA/TSRA AND THIS IS A LITTLE DISCONCERTING AS IT APPEARS THAT WE WILL SEE SOME LATE MORNING/EARLY AFTERNOON SURFACE HEATING TO COMBINE WITH RAPIDLY FALLING TEMPS ALOFT. EXPECT FIRST BATCH OF SHRA/TSRA TO CLEAR MY EASTERN ZONES BY 18Z...BUT WITH SOME SUN IN IT/S WAKE...EXPECT SCT SHRA/TSRA TO REDEVELOP THIS AFTERNOON. NAM/RUC PROFILES SUGGEST MAIN QUESTION ABOUT HOW ROBUST THE REDEVELOPMENT WILL BE IS HOW MUCH SURFACE HEATING OCCURS...AND WHETHER THIS HEATING CAN OVERCOME SOME WEAK MID LEVEL CAPPING. SVR POTENTIAL NOT GREAT THIS AFTERNOON GIVEN VERY WEAK WIND FIELDS AS THE TROUGH AXIS WILL BE OVERHEAD. HOWEVER...FALLING TEMPS ALOFT MAY PROVIDE AN INCREASED HAIL THREAT. UPDATED POPS THIS MORNING TO BOOST MORNING POPS...AND THEN DROP TO SCT COVERAGE THIS AFTERNOON. PREVIOUS DISCUSSION FOLLOWS... STRONG UPPER LOW WILL DIG INTO THE FCST AREA TODAY. SHWRS AND TRWS OVER WRN NY AND PA ALREADY MVG INTO THE AREA. THIS ACTIVITY ALONG WITH BKN TO OVC CLDS WILL HELP LIMIT HTG DURING THE DAY AND THUS LIMIT PTNL FOR SVR. DESPITE THE INSTABILITY AND DECENT MID LVL WIND PROFILE...LACK OF BLDG ENERGY WILL INHIBIT SVR. XCPTN COULD BE OVER THE FAR SE WHERE THE BEST CHANCE OF HTG COULD ALLOW FOR SOME STRONGER ISLTD CELLS. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/... UPR LOW LINGERS OVER NRN NEW ENG THRU THE PD. THIS COLD POOL ALOFT SHD BRING SOME SCT SHWRS TO NRN AND ERN NY...AND PERHAPS IN THE NRN AND ERN PARTS OF THE FCST AREA. GOOD LOW LVL DRY AIR WILL LIMIT THE CHANCE FOR SHWRS...AND RDGG OVER THE WRN ZONES SHD INHIBIT SHWRS THERE. OTRW...GNRLY DRY CONDS WITH COOLER AND DRIER AIR WILL BE OVER THE AREA THRU THE PD. MODELS HAVE SHOWN DECENT RUN TO RUN CONSISTENCY AND GRIDDED DATA NEEDED LTL ADJUSTMENT. GNRLY FLWD MAV GUID FOR TEMPS WITH A BLEND TWRD THE PRVS FCST. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... MDLS CONTINUE TO ADVERTISE RE-AMPLIFICATION OF THE NE U.S. TROF BY LATE WEEK...WITH POS PNA PTRN MORE TYPICAL OF THE COOL SEASON. S/WV`S ROTATING THRU THIS BUCKLING FLOW WILL HAVE THE POTNL TO SET OFF ISOLD TO WDLY SCT CONVECTION AT ANY TIME...BUT BEST CHCS ATTM APPEAR TO BE WITH STRONGER WAVES PROGGED FOR TUES NGT/WED AND AGAIN ON FRI. TEMPS WILL AVG A BIT BLO NORMAL FOR THIS PD. HPC GUIDANCE LOOKED GOOD AND ONLY MINOR TWEEKS WERE MADE. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... THIS AFTN...TSRA MAINLY CNTRL AND NRN NY AFFECTING RME/SYR/ITH WTIH MVFR CONDITIONS. VFR XPCTD TO PREVAIL ELSEWHERE THRU THE AFTN. LATER TNGT, MOIST AND COOLER NNW FLOW DVLPS WITH MDLS SHOWING SATURATION OF LOWEST LVLS AT MOST SITES AFTER 06Z. NOTED LOW CLDS AND CIGS IN THE 0.5-1K FT RNGT EARLIER THIS MRNG OVER PORTIONS OF MI, AND BELIEVE THIS POTNL EXITS TNGT ACRS THE BGM CWA...AIDED BY UPSLOPE FLOW INTO THE SRN TIER. MVFR FCST FOR MOST SITES AFTER 06Z....WITH PSBLTY OF IFR AT BGM/ITH AND RME TWDS DAYBREAK. MOST SITES SHUD BREAK OUT TO VFR BY LATE SUN MRNG. WINDS LGT AND GNRLY OUT OF THE NW THRU TNGT...THEN INCREASING TO 10-15 KTS ON SUN MRNG. SUN NGT THRU TUES...VFR BUT POTNL FOR DENSE EARLY MRNG VLY FOG AT ELM. TUES NGT/WED...POTNL FOR SCT MVFR IN TSRA. THU...VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DGM NEAR TERM...DGM/JMA SHORT TERM...DGM ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 208 PM EDT FRI AUG 1 2008 .SYNOPSIS... HIGH PRESSURE WILL BRING PARTLY SUNNY SKIES TO NEW YORK AND PENNSYLVANIA TODAY. A STORM SYSTEM ADVANCING THROUGH THE GREAT LAKES, WILL SPREAD SCATTERED SHOWERS AND THUNDERSTORMS, INTO OUR REGION LATE TONIGHT AND SATURDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... PREVIOUS FORECAST IN GOOD SHAPE THIS MORNING...HAVE ONLY NEEDED TO MAKE MINOR TWEAKS TO MORNING SKY COVER AS STRATOCU FROM BGM NORTH AND EAST IS PRETTY PERSISTENT EARLY THIS AM. AS THE MORNING PROGRESSES...EXPECT THIS TO MIX OUT...WITH NAM/RUC LLEVEL RH PROGS AND CU RULE PROGS SUGGESTING THE SAME. WILL KEEP SKIES PSUNNY FOR THE DAY FOR ALL BUT NE PA AS PLENTY OF CU WILL HANG AROUND. AS FOR SHRA CHANCES...12Z BUF/ALB RAOBS SHOW SUBSTANTIAL CAP IN PLACE IN THE MID LEVELS. CURRENT 500HPA ANALYSIS INDICATES A SHORTWAVE MOVING THROUGH WESTERN PA ATTM. HOWEVER...ALOFT WE/LL ACTUALLY FIND OURSELVES IN THE RIGHT EXIT REGION OF A 90KT JET MAX OVER THE NORTHERN GREAT LAKES. IN ADDITION...LLEVEL MOISTURE WILL BE LESS THAN YESTERDAY. FINALLY... GIVEN THAT WE WERE ONLY ABLE TO GENERATE A FEW SHRA WITH A COLD FRONTAL PASSAGE YESTERDAY AFTERNOON...FEEL THAT WITH NO ADDITIONAL LLEVEL FOCUS...WE WILL REMAIN DRY TODAY. SO...HAVE CONTINUED WITH NO PRECIP MENTION IN THE ZONES. UPDATED GRIDS/PRODUCTS ARE OUT. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... TROF ADVANCING THROUGH THE GREAT LAKES WILL DIVE INTO NY LATE TONIGHT. SHORT WAVES ROTATING AROUND THE TROF BASE WILL SLIDE THROUGH NY AND PA SATURDAY, WEAKENING AS THEY MOVE EAST AWAY FROM THE UL COLD POOL. WEAK WIND FIELD AND LONG/SKINNY CAPE PROFILE (ABOUT 500-800 J/KG) SUGGESTS SEVERE WEATHER IS NOT LIKELY. TIMING IS ALSO AN ISSUE, AS THE BEST LIFT IS DURING THE MORNING HOURS. CURRENT SPC RISK AREA JUST SOUTHEAST OF FA LOOKS GOOD. WOULDN`T EXPECT A SEVERE THREAT OVER UPSTATE NY AND NORTHEAST PA UNLESS SYSTEM SLOWS APPRECIABLY AND COMES THROUGH AT MAX HEATING. EVEN THEN, IT WOULD BE WORKING WITH WEAK KINEMATICS. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... AFTER SOME TEMPORARY RIDGING EARLY IN THE WEEK...THE POS PNA PTRN IS XPCTD TO RE-ESTABLISH ITSELF FOR MID TO LATE WEEK. AS USUAL...TIMING OF INDIVIDUAL S/WV`S DIFFICULT AT THIS TIME RNG..BUT GUIDANCE SUGGESTS BEST POTNL WILL BE WITH STRONGER SYSTEMS ON WED AND FRI. HOWEVER...CAN`T RULE OUT ISOLD TO WDLY SCT ACTIVITY ON ANY GIVEN DAY WITH THIS DVLPNG PTRN. FOLLOWED HPC CLOSELY AS TEMPS AND POPS LOOKED GOOD. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... VFR WILL PREVAIL THIS AFTN INTO THE EVNG HRS....THEN MVFR TO PSBLY IFR CONDITIONS ON SAT MRNG AS IMPRSV S/WV ROTATES THRU WITIH ATTENDANT PCPN. ATTM IT APPEARS THAT VSBY RESTRICTIONS AT ELM LATER TNGT WILL BE DUE TO APRCHG PCPN...AS CROSSOVER TEMP IN THE U50S AND INCRSNG CLD DECK LATER TGNT SHUD INHIBIT FORMATION OF DENSE VLY FOG. XPCT PCPN TO SPREAD EWD GNRLY AFTER 11Z WTIH MVFR CONDITIONS MOST AREAS...AND POTNL FOR IFR SPCLY ON THE HILLTOPS. ELM/SYR MAY SCATTER OUT BEFORE 18Z TMRW. OUTLOOK... SAT NGT...POTNL FOR MVFR CIGS LATE ALL AREAS IN -SHRA...GNRLY AFT 06Z. SUN...PSBL MVFR IN THE MRNG...OTRW VFR. SUN NGT THRU TUES...VFR BUT POTNL FOR DENSE EARLY MRNG VLY FOG AT ELM. TUES NGT/WED...POTNL FOR SCT MVFR IN TSRA. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DJP NEAR TERM...JMA SHORT TERM...DJP ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 146 AM EDT FRI AUG 1 2008 .SYNOPSIS... A WEAK RIDGE OF HIGH PRESSURE WILL BRING PARTLY CLOUDY SKIES AND DRY CONDITIONS THROUGH FRIDAY. A STORM SYSTEM WILL BRING A CHANCE OF SHOWERS AND THUNDERSTORMS LATE FRIDAY NIGHT AND SATURDAY, FOLLOWED BY IMPROVING CONDITIONS ON SUNDAY AS HIGH PRESSURE BUILDS EAST FROM THE GREAT LAKES. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... WATER VAPOR LOOP SHOWS A SHORT WAVE MOVING EAST OF THE AREA OFF THE NEW ENGLAND COAST THIS EVENING... WITH VERY DRY MID-LEVEL AIR MOVING INTO THE AREA BEHIND THIS SYSTEM. PATCHY CLOUDS WILL LINGER ACROSS PARTS OF THE AREA TONIGHT... WITH THE NAM/RUC MOISTURE FIELDS INDICATING SOME 2 TO 4 KFT BASED SC CLOUDS LATE TONIGHT THROUGH EARLY FRIDAY MORNING. && .SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY/... FRIDAY...H5 HEIGHTS RISE SLIGHTLY IN ADVANCE OF NEXT SHORT WAVE TROF WHILE NORTHWEST SFC FLOW CONTINUES. ENOUGH LOW LEVEL MOISTURE AND INSTABILITY PRESENT FOR SCT/BKN CUMULUS BUT MID LEVEL CAP WILL CONTINUE TO SUPPRESS CONVECTIVE ACTIVITY. KEPT FORECAST AREA DRY EXCEPT FOR NRN CWA WHERE SLIGHT CHC POPS ARE INCLUDED DURING THE AFTERNOON. MAXES WILL GENERALLY BE AROUND 80. FRIDAY NIGHT/SATURDAY...NEXT H5 TROF DROPS INTO REGION LATE FRIDAY NIGHT WITH SHORT WAVE PROGGED TO CROSS AREA ON SATURDAY. NAM FURTHER NORTH WITH FEATURE THAN GFS WITH ECMWF LEANING TOWARD THE NAM. CONTINUED WITH CHC/SLIGHT CHC POPS LATE FRIDAY NIGHT AND CHC POPS ON SATURDAY. WITH ABUNDANT CLOUDINESS MAXES WILL ONLY REACH IN THE MID TO UPPER 70S. SATURDAY NIGHT...AFTER LINGERING EVENING SHOWERS ACTIVITY SHOULD END AS FORCING PULLS WELL EAST OF FA. SKIES WILL BECOME PARTLY CLOUDY WITH TEMPS FALLING INTO THE 50S. SUNDAY...SFC HIGH PRES FROM THE UPR GREAT LAKES TO OHIO VLY WILL BUILD EAST INTO REGION. PARTLY SUNNY SKIES EXPECTED WITH CHC POPS DURING THE AFTERNOON FAR NRN CWA WHERE H5 COLD POOL IS STRONGEST. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... MODELS IN PRETTY GOOD AGREEMENT THIS AFTERNOON ON THE EXTENDED. HAVE FOLLOWED GUIDANCE FROM HPC WHICH LEANS MORE TOWARDS A GFS/GEFS BLEND VS. THE ECMWF. ANOMALOUS EASTERN TROUGH LIFTS OUT EARLY IN THE PERIOD WITH MORE ZONAL FLOW FOR TUESDAY/WEDNESDAY BEFORE EASTERN CONUS TROUGHING TRIES TO REDEVELOP BY LATER NEXT WEEK. NICE ON MONDAY AS HEIGHTS BUILD BEFORE NEXT COLD FRONT APPROACHES ON TUESDAY. THE DETAILS ON WHEN THIS FRONT PUSHES THROUGH...AND HOW FAR SOUTH IT SETTLES WILL CERTAINLY HAVE A BIG IMPACT ON PRECIP THIS COMING WEEK. HAVE CARRIED CHC POPS TUESDAY AND WEDNESDAY FOR SHRA/TSRA WITH THE FRONT IN OUR VICINITY...DROPPING TO SCHC ON THURSDAY AS AT THIS POINT IT APPEARS THE FRONT WILL BE FAR ENOUGH SOUTH OF OUR AREA TO DRY THINGS OUT SOME. AS FOR TEMPS...MONDAY LOOKS SEASONABLE /NEAR 80F/. TEMPS WILL WARM AHEAD OF THE COLD FRONT...INTO THE MID AND UPPER 80S FOR TUESDAY BEFORE GRADUALLY FALLING BACK TOWARDS NORMAL FOR WEDNESDAY AND THURSDAY AS THE FRONT SETTLES THROUGH THE REGION. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... PATCHY FOG WILL LIKELY DVLP OVR THE NEXT FEW HRS ALTHOUGH WITH A FEW MID CLDS ARND...CONDS SHD NOT GET TO LOW...MSTLY STAYING IN THE MVFR TO OCNL IFR RANGE AT ELM. FOG WILL BURN OFF EARLY FRI LVG VFR CONDS FOR THE REMAINDER OF THE TAF PD. OUTLOOK... FRIDAY NIGHT...CHC MVFR/IFR SHRA/TSRA ALL SITES...ESP AFTER MIDNIGHT. SATURDAY...CHC MVFR SHRA ESP THROUGH NOON OVER CNY SITES WITH VFR AT AVP. SUNDAY THRU TUESDAY...MORNING MVFR/IFR FOG POSSIBLE AT ELM. OTHERWISE VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...RRM NEAR TERM...MSE SHORT TERM...RRM LONG TERM...JMA AVIATION...DGM/MSE ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 1021 AM CDT SAT AUG 2 2008 .DISCUSSION... AREA OF TSTORMS ONGOING ACROSS NCNTRL NDAK WHERE 50KT LLJ AND +50KT OF 0-6KM BULK SHEAR EXISTS. RUC SHOWS AXIS OF INSTABILITY MOVING INTO EXTREME NORTHWESTERN FA LATE THIS MORNING. INCREASED POP IN THIS AREA TO LIKELY THROUGH EARLY AFTERNOON. EXPECT SUBSIDENCE BEHIND SW TO HELP DISSOLVE CONVECTIVE DEBRIS. NEEDED TO CHANGE TEMP CURVE TO ACCOUNT FOR LESS INSOLATION THROUGH EARLY AFTERNOON... STILL KEEPING INHERITED MAX TEMP FORECAST AS THERMAL AXIS REMAINS CENTERED OVER FA. && AVIATION...TSRA LOOKS TO BE CONFINED TO NW AND FAR NORTHERN FA AS AREAS TO THE SOUTH UNDER STRONG CAP. OVERALL VFR CONDITIONS WITH ISOLD MVFR CIGS/VSBY UNDER STRONGER STORMS. && .PREV DISCUSSION... /ISSUED 330 AM CDT SAT AUG 2 2008/ DISCUSSION... FORECAST CHALLENGE CONTINUES TO BE CONVECTIVE POTENTIAL AND TEMPERATURES. MODELS SIMILAR THROUGH PERIOD. GFS HORRIBLE INITIALIZING SURFACE DEWPOINTS AND WILL USE NAM IN SHORT TERM AND BLEND THERE AFTER. IN THE NEAR TERM WILL MONITOR CONVECTION ALONG INTERNATIONAL BORDER FOR EARLY MORNING MENTION. CELLS OUT RUNNING FAVORED CONVERGENCE WITH LOW LEVEL JET AND ALSO PROPAGATING INTO MORE STABLE AIRMASS AND WEAKENING TRENDS HAVE BEEN NOTED. LATER IN THE DAY AND TONIGHT INSTABILITY/CAPE AXIS SHIFTS INTO THE CENTRAL DAKOTAS WITH WEAK SURFACE BOUNDARY AND REMAINS STATIONARY OVERNIGHT. SUFFICIENT SHEAR EXISTS HOWEVER WILL BE A FAIRLY STRONG CAP IN PLACE LIMITING CONVECTION POTENTIAL AT LEAST ACROSS THE SOUTHERN FA. WITH INSTABILITY AXIS STATIONARY OVER CENTRAL DAKOTAS SEVERE POTENTIAL SOMEWHAT IN QUESTION WITH FAVORED LOCATION OVER WESTERN/NORTHERN FA. ALSO LATER TONIGHT LOW LEVEL JET UNIMPRESSIVE WITH ANY CONVERGENCE EITHER WELL NORTH IN CANADA OR TO OUR SOUTH. FOR THIS WILL KEEP POPS LOW. WITH INCREASED MIXING...THERMAL RIDGE SHIFTING OVER FA AND AT LEAST PARTIAL SOLAR TEMPERATURES SHOULD RANGE A LITTLE ABOVE AVERAGE AND REMAIN MILD OVERNIGHT AS SURFACE MOIST FLUX ADVECTS HIGHER DEWPOINTS INTO FA. BETTER CHANCES FOR CONVECTION LOOK TO BE SUNDAY/SUNDAY EVENING AS BOUNDARY AND INSTABILITY AXIS SHIFT OVER FA. REGION ALSO COMES UNDER EXIT REGION OF SPEED MAX FOR UPPER SUPPORT. CURRENT POPS IN ORDER AT THIS POINT BUT MAY NEED TO BE INCREASED IF TRENDS CONTINUE. CONVECTION WHICH DOES OCCUR SHOULD WEAKEN AFTER DARK AS AIRMASS STABILIZES AND LOW LEVEL JET CONVERGENCE CONFINED TO OUR SOUTH. COLUMN COOLS SLIGHTLY BUT CLOUDS WILL HAVE BIGGEST IMPACT ON TEMPERATURES. WITH UNCERTAINTY WILL LET CURRENT FORECAST TEMPERATURES RIDE. NW FA WILL SEE STRONGER COLD ADVECTION AND LOW LEVEL DRYING FOR COOLEST TEMPERATURES. ON MONDAY BOUNDARY SHIFTS SOUTH WITH MAIN FORCING AND INSTABILITY ACROSS SD/S MN. 310K ISENTROPIC SURFACE ALSO SHOWING GENERAL DOWNGLIDE SO NAM QPF SEEMS TOO FAR NORTH AND FAVOR GFS SOLUTION AND WILL KEEP POPS LOW. REMAINDER OF PERIOD LOOKS QUIET WITH NEAR NORMAL TEMPERATURES UNTIL POSSIBLY SECOND HALF OF WORK WEEK WHEN STRONGER COLD FRONT DROPS THROUGH FA. MINIMAL CHANGES PLANNED IN LONGER RANGE. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ JK nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OH 719 AM EDT SAT AUG 2 2008 .SYNOPSIS... COLD FRONT OVER EXTREME NORTHERN OHIO AND NORTHWEST PENNSYLVANIA WILL CONTINUE TO MOVE SOUTH TODAY. HIGH PRESSURE WILL BEGIN BUILDING IN FROM THE WEST TONIGHT AND MOVE EAST OF THE REGION MONDAY NIGHT. A FRONTAL SYSTEM WILL AFFECT THE AREA TUESDAY AND WEDNESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... COLD FRONT SAGGING INTO THE AREA. SOME SHOWERS/THUNDERSTORMS COULD BRUSH NORTHWEST PA THROUGH DAYBREAK. SOME CLOUDS WERE OVER MICHIGAN AND THEY WILL MOVE ACROSS NORTHWEST OHIO THIS MORNING. THE FLOW WILL BE CYCLONIC TODAY AND A LITTLE VORT WILL MOVE THROUGH THE FORECAST AREA. ALL THE MODELS INCLUDING THE RUC AGREE THAT THERE COULD BE SOME SHOWERS/THUNDERSTORMS THROUGH 17Z. KEPT THE THREAT EAST OF CLE AND CAK...THERE SEEMED TO BE ENOUGH MOISTURE AND CAPE. THE AIRMASS IS TRYING TO DRY OUT ESPECIALLY NORTHWEST OHIO THIS AM...DID NOT MENTION DENSE FOG IN ZONES/GRIDS...THIS WILL HAVE TO BE MONITORED. WENT CLOSER TO THE MOS MAV NUMBERS FOR THE HIGHS...THE GRIDDED MOS SEEMED TOO WARM. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... THE LAKE AND 850 MB TEMPERATURE DIFFERENCE WILL BE NEAR 11C TONIGHT. THIS COULD GENERATE SOME LAKE EFFECT CLOUDS IN THE EASTERN AREAS...THE WEST SHOULD BE MOSTLY CLEAR. WITH A NORTH WIND THE LAKESHORE AREAS WILL REMAIN WARMER THAN INLAND LOCATIONS. SUNDAY THROUGH MONDAY WILL BE DRY WITH SOME CLOUDS ESPECIALLY SUNDAY IN THE EASTERN AREAS AND EVERYWHERE IN THE AFTERNOON AS A WARM FRONT WILL BEGIN TO APPROACH THE AREA. WENT CLOSE TO MAV MOS GUIDANCE. PUT A CHANCE OF SHOWERS IN NORTHWEST OHIO MONDAY NIGHT AS FRONTAL SYSTEM MOVING IN. BETTER CHANCE TUESDAY AND TUESDAY NIGHT AS THE FRONTAL SYSTEM MOVES THROUGH. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... BY WEDNESDAY BOTH GFS AND ECMWF ARE PRETTY AGGRESSIVE IN PUSHING SURFACE COLD FRONT THROUGH THE AREA. LOOKS LIKE BEST CHANCE FOR SHOWERS AND THUNDERSTORMS WOULD BE WITH THE COLD FRONT ON WEDNESDAY ACROSS THE AREA. FOR NOW KEPT THURSDAY DRY ACROSS THE AREA WITH DRIER AIR MOVING IN BEHIND FRONT. ALSO...UPPER LOW WILL BE PUSHING DOWN INTO THE AREA BUT THINKING ANY INFLUENCE WITH CLDS AND SHOWERS WOULD NOT BE UNTIL FRIDAY UNTIL UPPER TROUGH SWINGS OVER THE AREA. TEMPS WILL GRADUALLY COOL OFF THROUGH THE PERIOD. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... COLD FRONT THROUGH SITES THIS MORNING WITH NORTHERLY FLOW DEVELOPING. UPPER TROUGH WILL MOVE THROUGH THE AREA THROUGH MID AFTERNOON SO WITH CU DEVELOPING ACROSS THE AREA MENTIONED SOME BKN CLDS MAINLY EAST CLE AND MFD. DURING AFTERNOON HOWEVER ANY BKN CU ALONG LAKESHORE MAY ACTUALLY PUSH INLAND ALLOWING LOCATIONS SUCH AS CLE TO BECOME SCT. ALSO TODAY HIGH PRESSURE WILL BUILD EASTWARD INTO THE AREA. HIGH PRESSURE MOVES CLOSER TO THE AREA TONIGHT. WITH THAT LOOKING FOR MAINLY CLEAR SKIES AFTER ABOUT 01Z TONIGHT. CLEAR SKIES AND HIGH PRESSURE BUILDING IN MAY ALLOW FOR SOME MVFR WITH POSSIBLE ISOL IFR AFTER 08Z SUN. GIVEN SOME REASONABLE CONFIDENCE ESP FOR PLACES LIKE FDY AND MFD...JUST MENTIONED A PREDOMINATE GROUP FOR VSBYS COMING DOWN TO MVFR LATE IN PERIOD. FOR EACH SITE DISPLAYED CONFIDENCE MEASURE ON THIS OCCURRING BY THE ASSIGNED VSBY. HIGHER CONFIDENCE LOCATIONS SHOWN BY MENTIONING PREDOMINATE 3SM BR WHILE KEPT EASTERN SITES AT 5SM BR. OUTLOOK...VFR SUNDAY AND MONDAY WITH HIGH PRESSURE OVER THE AREA. MVFR POSSIBLE WITH COLD FRONT IN THE AREA TUESDAY AFTERNOON AND TUESDAY NIGHT. VFR WEDNESDAY. && .MARINE... WINDS MAINLY LIGHT ACROSS THE AREA TODAY WITH UPPER TROUGH SWINGING THROUGH THE AREA. HIGH PRESSURE BUILDS IN TONIGHT ALLOWING FOR WINDS AND WAVES TO PICK UP IN THE 2 TO 4FT RANGE FOR A PERIOD LATE TONIGHT AND SUNDAY MORNING. THIS WILL BE SHORT LIVED THOUGH AS HIGH BUILDS OVERHEAD. HIGH PRESSURE WILL CONTINUE ACROSS THE AREA MONDAY ALLOWING FOR LIGHT WINDS AND WAVES TO CONTINUE. NO HEADLINES EXPECTED INTO EARLY NEXT WEEK. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...NONE. && $$ SYNOPSIS...KIELTYKA NEAR TERM...KIELTYKA SHORT TERM...KIELTYKA LONG TERM...ABE AVIATION...ABE MARINE...ABE oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 1007 AM CDT FRI AUG 1 2008 .UPDATE...WE MADE A FEW TWEAKS TO POPS AND TEMPERATURES FOR THIS AFTERNOON. WITH CLEAR SKIES...TEMPS ARE RUNNING A BIT WARMER THAN YESTERDAY. USED A MODEL CONSENSUS APPROACH TO ARRIVE AT HIGH TEMPS 1 OR 2 DEGREES WARMER THAN PREVIOUS FORECAST. THOUGH NOT A LARGE CHANGE...IT DOES PUSH MORE OF THE REGION ABOVE 100 DEGREES THIS AFTERNOON. RAOBS SUGGEST DEWPOINTS SHOULD DROP CLOSE TO THE NAM FORECAST VALUES...WHICH WOULD PUT HEAT INDICES RIGHT AT 105 FOR A LOT OF THE REGION. GIVEN THAT THIS...AND DURATION OF THE HEAT ARE BOTH CRITERIA FOR A HEAT ADVISORY...WE WILL BE TAKING A CLOSE LOOK AT THE NEED FOR AN ADVISORY OVER THE WEEKEND. TEMPERATURES WILL RISE...BUT HUMIDITY WILL LIKELY FALL...RESULTING IN BORDERLINE CRITERIA BY THE NUMBERS...BUT THE LIKELIHOOD OF INCREASING STRESS FROM THE WARMER TEMPERATURES. ALSO ADDED A SLIGHT CHANCE FOR RAIN TO A SMALL PART OF WESTERN NORTH TEXAS THIS AFTERNOON. THE REMNANT TROUGH AXIS WAS REFLECTED AT SURFACE FROM BENJAMIN TO WICHITA FALLS AND UP INTO SOUTHERN OKLAHOMA. AT MID LEVELS...HOWEVER...THE TROUGH...MOISTURE...AND LIFT WERE LOCATED A BIT FARTHER SOUTH. THE NAM AND RUC INDICATE JUST ENOUGH LIFT AND INSTABILITY THIS AFTERNOON...THAT STORMS FORMING OVER NORTH CENTRAL TEXAS MAY PROPAGATE TOWARD A BLUEGROVE...BENJAMIN LINE BEFORE DISSIPATING. && BURKE && .PREV DISCUSSION... /ISSUED 416 AM CDT FRI AUG 1 2008/ DISCUSSION... THE UPPER RIDGE CENTERED OVER THE SOUTHERN AND CENTRAL ROCKIES...WILL BUILD EASTWARD ACROSS THE SOUTHERN AND CENTRAL PLAINS THIS WEEKEND. THE LIGHT SOUTHEAST FLOW TODAY WILL KEEP HUMIDITY LEVELS UP ACROSS THE EASTERN 2/3RDS OF THE AREA WHICH WILL RESULT IN HEAT INDEX VALUES APPROACHING 105 DEGREES. HUMIDITY LEVELS WILL GRADUALLY DECREASE OVER THE WEEKEND WITH A SOUTHWESTERLY COMPONENT TO THE SURFACE WINDS. THE HEAT WILL LAST INTO AT LEAST THE EARLY TO MID PART OF NEXT WEEK BEFORE A FRONTAL BOUNDARY APPROACHES FROM THE NORTH. WILL ISSUE SPS CONCERNING THE UPCOMING HEAT...BUT WILL NOT ISSUE A HEAT ADVISORY AT THIS TIME. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 100 74 102 76 / 0 0 0 0 HOBART OK 103 75 104 77 / 0 0 0 0 WICHITA FALLS TX 103 78 104 77 / 10 0 0 0 GAGE OK 102 70 102 73 / 0 0 0 0 PONCA CITY OK 99 75 99 76 / 0 0 0 0 DURANT OK 99 75 99 74 / 10 0 0 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ 06 ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 143 PM EDT SAT AUG 2 2008 .SYNOPSIS... A WEAK COLD FRONT WILL SAG SOUTH ACROSS THE AREA FROM THE NORTH TODAY AND STALL OUT OVER CENTRAL SOUTH CAROLINA AND GEORGIA BEFORE DISSIPATING. AN UPPER LEVEL RIDGE WILL THEN BUILD IN FROM THE WEST EARLY IN THE WEEK. ANOTHER WEAK COLD FRONT WILL ARRIVE FROM THE NORTH LATE THURSDAY. && .NEAR TERM /THROUGH SUNDAY/... AFTER COLLABORATING WITH NEIGHBORING OFFICES...I/VE RAISED POPS INTO THE LIKELY CATEGORY OVER A GOOD BIT OF THE NC FOOTHILLS AND PIEDMONT AND THE UPSTATE AND NW PIEDMONT OF SC. THE RUC TAKES A SHORT WAVE ACROSS THE FA FROM 18 TO 21 UTC. IT GENERATES GOOD LLVL CONVERGENCE AHEAD OF THE WAVE...AND INITIATES CONVECTION BY AROUND 17 UTC ALONG THE EASTERN SLOPES OF THE BLUE RIDGE. CAE POINTED OUT THAT THE EXPERIMENTAL SEA BREEZE WRF RUN FROM NSSL DOES SOMETHING SIMILAR. WHILE THE OPERATIONAL NAM IS SLOWER TO DEVELOP CONVECTION...IT/S ORIENTATION ACROSS THE UPSTATE AND SRN NC PIEDMONT IS SIMILAR TO THE OTHER MODELS BY LATE IN THE DAY. WITH SUBCLOUD TEMP/DWPT DEPRESSIONS INCREASING TO AROUND 30 DEGREES AND WITH MODERATE THETA-E LAPSES...THE POTENTIAL FOR MICROBURSTS IS HIGH TODAY. THOUGH STORM MOTIONS OVER 10 KTS MAY DELAY THIS PROCESS A BIT UNTIL CONVECTION BECOMES MORE ORGANIZED...WHICH I THINK IT WILL...THOUGH BY THAT TIME IT MIGHT BE MORE OF AN ISSUE FOR RAH AND CAE. THE MID SHIFT HAD ALL THIS WELL IN HAND...AND ALL I REALLY DID WAS INCREASE POPS IN THE AREAS WHERE IT IS LOOKING MORE LIKELY THAT TSTMS WILL DEVELOP. && .SHORT TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... AT 110 PM EDT SATURDAY...THE MAIN STORY FOR THE SHORT TERM PERIOD IS THE HEAT...AS MID LVL RIDGING HOLDS ACRS THE SOUTHEAST STATES. MONDAY WILL START OUT A LITTLE DRIER THANKS TO SOME DOWNSLOPE FLOW AND RELATIVELY DEEP MIXING (DEWPTS IN THE MID 60S). AMONG THE NAM/GFS/SREF/ECM...THERE IS SOME DISAGREEMENT ON WHERE A SFC TROF WILL SET UP BETWEEN A HIGH OVR THE OH VLY AND A BERMUDA HIGH TO THE SE. THE TROF WILL LIKELY BE A FOCUS FOR SOME CONVECTION...AS AREA TO THE S WILL BE UNSTABLE...WHILE RELATIVELY STABLE AIR WILL FILTER IN FROM THE N. FOR NOW...I JUST ADDED A SLGT CHC POP FOR THE HIGH TERRAIN AND ALONG THE SRN FRINGE OF THE CWFA. TUESDAY AND WEDNESDAY HAVE THE POTENTIAL TO BE QUITE HOT...AS H85 THERMAL RIDGE AXIS REMAINS ACROSS THE CAROLINAS AND MID ATLC. GUIDANCE SEEMS TO BE IN GENERAL AGREEMENT ON WEAK RETURN FLOW STARTING LATE MONDAY...ALLOWING DEWPTS TO SLOLY CREEP UPWDS. MAX TEMPS LOOK TO BE IN THE MID TO UPR 90S BOTH DAYS ACRS THE PIEDMONT. CURRENT GRIDS HAVE HEAT INDEX VALUES IN THE 100-105 RANGE TUESDAY AND 103-108 RANGE WEDNESDAY. THIS LINES UP WELL WITH HPC MEDIUM RANGE HEAT INDEX GUIDANCE. SO WILL CONTINUE TO HIGHLIGHT IN THE HWO. POPS WILL STILL BE MEAGER BOTH DAYS...WITH SLGT CHC IN THE MTNS TUES AFTN...AND ACRS ENTIRE CWFA WEDNESDAY AFTN. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... AS OF 2 AM SATURDAY...IN THE MEDIUM RANGE GOING INTO WEDNESDAY...SMALL DIFFERENCES APPEAR BETWEEN THE GFS AND THE 12Z ECMWF. THE GFS TAKES THE FRONT FASTER SOUTHEAST ACROSS OUR AREA EARLY THURSDAY AND THE EC HAS THE FRONT JUST REACHING THE NC MOUNTAINS BY MID DAY THURSDAY. AT ANY RATE...CHANCES FOR CONVECTION WILL BE SMALL WEDNESDAY AND INCREASING WEDNESDAY NIGHT AND THURSDAY. TEMPERATURES WILL STILL BE WELL ABOVE NORMAL WEDNESDAY...BUT WITH THE CLOUD OVER AND LOWERING HEIGHTS ON THURSDAY THE HIGHS WILL BE HELD DOWN A FEW DEGREES. AS THIS FIRST FRONT STALLS OUT ACROSS OUR SOUTHERN ZONES GOING INTO FRIDAY...ANOTHER SHORTWAVE WILL ROTATE SOUTHEAST AROUND THE UPPER LOW TOWARD THE NC MOUNTAINS. THE RESULT WILL BE A CONTINUED CHANCE OF SHOWERS AND THUNDERSTORMS MAINLY IN THE AFTERNOONS AND EVENING INTO NEXT WEEKEND. HIGH TEMPERATURES SHOULD BE NEAR NORMAL AS WE WILL BE NEAR THE BASE OF THE UPPER TROUGH. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... A FEW TSTMS HAVE MOVED INTO THE NC MTNS. ACTIVITY SHOULD QUICKLY INCREASE OVER THE NEXT FEW HOURS. HAVE INCLUDED VCTS AT NC MTN AND FOOTHILL TAF SITES AS WELL AS KGSP AND KGMU. THUNDERSTORMS THIS AFTERNOON WILL LIKELY PRODUCE A LOT OF WIND...SOMETHING TO WATCH OUT FOR AT LOCAL AIRFIELDS. WINDS WILL GENERALLY BE OUT OF THE SW THIS AFTERNOON...SAVE FOR KAVL AND KHKY WHICH ARE ON THE WEST SIDE OF THE LEE TROUGH. INCLUDED MVFR FOG AT MANY SITES TONIGHT PER THE HIGHER MOS PROBABILITIES. CHANCES WILL BE MUCH BETTER FOR FOG AT ANY SITES THAT SEE SOME RAIN. WINDS WILL BE LIGHT OUT OF THE NORTH TOMORROW...THOUGH THEY WILL PROBABLY TURN BACK OUT OF THE SOUTH LATER IN THE AFTERNOON. OUTLOOK...BELOW NORMAL CHANCES OF RAINFALL WILL LAST FROM SUNDAY THROUGH TUESDAY. A LITTLE FOG AND HAZE IS LIKELY IN THE MORNINGS...ESPECIALLY AT KAVL. CHANCES OF TSTMS WILL IMPROVE ON WEDNESDAY. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...PAT NEAR TERM...MCAVOY SHORT TERM...ARK LONG TERM...DEO AVIATION...MCAVOY sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 738 PM EDT FRI AUG 1 2008 .SYNOPSIS... A WEAK COLD FRONT WILL APPROACH FROM THE NORTHWEST TONIGHT. THIS FRONT WILL CROSS THE AREA ON SATURDAY...THEN WILL WEAKEN. AN UPPER LEVEL RIDGE WILL THEN BUILD IN FROM THE WEST NEXT WEEK. ANOTHER COLD FRONT WILL ARRIVE BY FRIDAY. && .NEAR TERM /THROUGH SATURDAY/... RUC INDICATES AXIS OF 500 MB SHORT WAVE TROUGH AND ASSOCIATED VORTICITY MAXIMUM HAVE MOVED TO THE FAR EASTERN PORTION OF THE CWA AND WILL BE EAST OF THE AREA THIS EVENING. IN THE WAKE OF THE TROUGH... DRY NORTHWEST FLOW HAS BROUGHT AIR MASS CONDUCIVE ONLY TO THE FORMATION OF SCATTERED CUMULUS WHICH WILL DISSIPATE AROUND SUNSET. THE OVERNIGHT PERIOD WILL BE CLEAR AND DRY WITH ONLY SCATTERED AREAS OF REDUCED VISIBILITY IN FOG AND HAZE TOWARD DAYBREAK. BUILDING RIDGE CENTRAL NORTH AMERICA AND RATHER VIGOROUS SHORT WAVE TROUGH SWINGING AROUND EASTERN CANADA TROUGH WILL DRIVE ANOTHER FRONT TOWARD THE SOUTHERN APPALACHIANS DURING THE DAY SATURDAY. NAM... GFS... AND SREF ARE REASONABLY CLOSE IN SUGGESTING THAT SUFFICIENT MOISTURE TO SUPPORT SCATTERED SHOWERS AND THUNDERSTORMS WILL ENTER FAR WESTERN ZONES BETWEEN 15Z AND 18Z SATURDAY THEN PROGRESS INTO EASTERN ZONES DURING AFTERNOON. MOISTURE IS NOT PARTICULARLY ABUNDANT WITH THIS SYSTEM... BUT DAYTIME HEATING WILL PROBABLY SERVE TO ENHANCE CONVECTIVE PRECIPITATION PRODUCTION EASTERN AND SOUTHERN ZONES DURING LATTER PART OF THE DAY. TEMPERATURE FORECASTS TONIGHT THROUGH SATURDAY ARE A BLEND OF CURRENT FORECASTS AND 12Z MOS GUIDANCE. && .SHORT TERM /SATURDAY NIGHT THROUGH TUESDAY NIGHT/... AT 120 PM EDT FRIDAY...MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT ON OVERALL UPR PAT FOR DAYS 3-5 (SUN-TUE). BASICALLY AN UPR RIDGE CENTERED OVR THE SRN PLAINS STATES AND AN ANOMALOUS H5 VORTEX OVR SE CANADA WILL SLOWLY PROGRESS EWD THRU THE PERIOD. MOST OF THE EASTERN SEABOARD WILL BE UNDER DRY NW UPR FLOW...WITH A WEAK SFC HI OVR GREAT LAKES AND OH VLY AND A BERMUDA HI EXTENDING INTO THE DEEP SOUTH. BETWEEN THE TWO SFC HIGHS...THERE WILL BE A TROUGH LINGERING ALONG THE EAST COAST DOWN TO CENTRAL MS/AL/GA AREAS. PREV MODEL RUNS PRETTY MUCH AGREED ON KEEPING THE BNDRY S OF OUR CWFA THRU MONDAY...WITH DRY NLY/NELY FLOW KEEPING THE AREA STABLE. HOWEVER...THE 12Z NAM AND GFS BOTH HAVE THE BNDRY LIFTING N ACROSS GA/SC AS A WEAK WAVE DEVELOPS INVOF NRN AL. SINCE THIS IS A NEW TREND...I WENT WITH CONTINUITY AND KEPT THE FCST DRY WITH NLY/NELY FLOW THRU MONDAY. THE DRY LOW LVLS AND GENERALLY MOSTLY SUNNY CONDITIONS WILL RESULT IN ABV AVG MAX TEMPS AND NEAR NORMAL MINS WITH POCKETS OF BELOW NORMAL MINS IN THE MTN VLYS. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 1 PM FRIDAY...BOTH THE HPC PREFERRED ECMWF AND THE GFS WERE CHARACTERISTICALLY SOUND WITH THE HANDLING OF THE UPPER LEVEL TROF. THE TROF WILL APPROACH THE AREA EARLY THURSDAY AND LINGER THROUGH THE WEEKEND AND INTO MONDAY. THE HPC SURFACE ANALYSIS CHARTS INDICATE A WEAK COLD FRONT MOVING IN FROM THE NORTH ON WEDNESDAY AND MOVING INTO THE CWFA LATE IN THE DAY FRIDAY. THIS FRONT LOOKS TO STALL OVER THE PIEDMONT OF THE CAROLINAS AND BRING AN INCREASED CHANCE OF PRECIPITATION STARTING THURSDAY AND CONTINUING THROUGH THE WEEKEND. THE MOUNTAINS WILL TEND TO SEE THE BEST CHANCE FOR PRECIPITATION EARLIER IN THE PERIOD WHILE THE UPSTATE STANDS TO SEE A BETTER CHANCE OVER THE WEEKEND. TEMPERATURES WILL TEND TO BE ABOVE AVERAGE BY 5-10 DEGREES ON WEDNESDAY AND THURSDAY AND DROP BACK DOWN TO NORMAL AS THE FRONT STALLS ACROSS THE AREA ON FRIDAY AND INTO THE WEEKEND. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... FEW TO SCT SC/AC THIS EVE...SCT CI OVERNIGHT. LOOK FOR MVFR VSBY IN FOG AND HAZE 10-13Z. LIGHT WINDS OVERNIGHT...THEN W TO SW 8-10KTS AHEAD OF APPROACHING COLD FRONT. MOISTURE INCREASES SAT WITH A CHANCE OF SHWRS/TSTMS AFTN-EVE. NOT A GREAT CHANCE BUT INCLUDED VCSH AND CB CLOUDS AT KAVL AFT 17Z. OUTLOOK...COLD FRONT WILL MOVE THROUGH THE AREA BY SUNDAY MORNING FOLLOWED BY HIGH PRESSURE AND MOSTLY VFR WEATHER SUNDAY THROUGH MONDAY. ISOLATED THUNDERSTORMS ARE POSSIBLE IN THE MOUNTAINS TUESDAY AND ACROSS THE CWA WEDNESDAY. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...JAT NEAR TERM...LGL SHORT TERM...ARK LONG TERM...ARK AVIATION...RB sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 215 PM EDT FRI AUG 1 2008 .SYNOPSIS... WEAK HIGH PRESSURE WILL MOVE INTO THE AREA TODAY. A WEAK COLD FRONT WILL APPROACH FROM THE NORTHWEST TONIGHT. THIS FRONT WILL CROSS THE AREA ON SATURDAY...THEN WILL WEAKEN. AN UPPER LEVEL RIDGE WILL THEN BUILD IN FROM THE WEST NEXT WEEK. && .NEAR TERM /THROUGH SATURDAY/... RUC INDICATES AXIS OF 500 MB SHORT WAVE TROUGH AND ASSOCIATED VORTICITY MAXIMUM HAVE MOVED TO THE FAR EASTERN PORTION OF THE CWA AND WILL BE EAST OF THE AREA THIS EVENING. IN THE WAKE OF THE TROUGH... DRY NORTHWEST FLOW HAS BROUGHT AIR MASS CONDUCIVE ONLY TO THE FORMATION OF SCATTERED CUMULUS WHICH WILL DISSIPATE AROUND SUNSET. THE OVERNIGHT PERIOD WILL BE CLEAR AND DRY WITH ONLY SCATTERED AREAS OF REDUCED VISIBILITY IN FOG AND HAZE TOWARD DAYBREAK. BUILDING RIDGE CENTRAL NORTH AMERICA AND RATHER VIGOROUS SHORT WAVE TROUGH SWINGING AROUND EASTERN CANADA TROUGH WILL DRIVE ANOTHER FRONT TOWARD THE SOUTHERN APPALACHIANS DURING THE DAY SATURDAY. NAM... GFS... AND SREF ARE REASONABLY CLOSE IN SUGGESTING THAT SUFFICIENT MOISTURE TO SUPPORT SCATTERED SHOWERS AND THUNDERSTORMS WILL ENTER FAR WESTERN ZONES BETWEEN 15Z AND 18Z SATURDAY THEN PROGRESS INTO EASTERN ZONES DURING AFTERNOON. MOISTURE IS NOT PARTICULARLY ABUNDANT WITH THIS SYSTEM... BUT DAYTIME HEATING WILL PROBABLY SERVE TO ENHANCE CONVECTIVE PRECIPITATION PRODUCTION EASTERN AND SOUTHERN ZONES DURING LATTER PART OF THE DAY. TEMPERATURE FORECASTS TONIGHT THROUGH SATURDAY ARE A BLEND OF CURRENT FORECASTS AND 12Z MOS GUIDANCE. && .SHORT TERM /SATURDAY NIGHT THROUGH TUESDAY NIGHT/... AT 120 PM EDT FRIDAY...MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT ON OVERALL UPR PAT FOR DAYS 3-5 (SUN-TUE). BASICALLY AN UPR RIDGE CENTERED OVR THE SRN PLAINS STATES AND AN ANOMALOUS H5 VORTEX OVR SE CANADA WILL SLOWLY PROGRESS EWD THRU THE PERIOD. MOST OF THE EASTERN SEABOARD WILL BE UNDER DRY NW UPR FLOW...WITH A WEAK SFC HI OVR GREAT LAKES AND OH VLY AND A BERMUDA HI EXTENDING INTO THE DEEP SOUTH. BETWEEN THE TWO SFC HIGHS...THERE WILL BE A TROUGH LINGERING ALONG THE EAST COAST DOWN TO CENTRAL MS/AL/GA AREAS. PREV MODEL RUNS PRETTY MUCH AGREED ON KEEPING THE BNDRY S OF OUR CWFA THRU MONDAY...WITH DRY NLY/NELY FLOW KEEPING THE AREA STABLE. HOWEVER...THE 12Z NAM AND GFS BOTH HAVE THE BNDRY LIFTING N ACROSS GA/SC AS A WEAK WAVE DEVELOPS INVOF NRN AL. SINCE THIS IS A NEW TREND...I WENT WITH CONTINUITY AND KEPT THE FCST DRY WITH NLY/NELY FLOW THRU MONDAY. THE DRY LOW LVLS AND GENERALLY MOSTLY SUNNY CONDITIONS WILL RESULT IN ABV AVG MAX TEMPS AND NEAR NORMAL MINS WITH POCKETS OF BELOW NORMAL MINS IN THE MTN VLYS. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 1 PM FRIDAY...BOTH THE HPC PREFERRED ECMWF AND THE GFS WERE CHARACTERISTICALLY SOUND WITH THE HANDLING OF THE UPPER LEVEL TROF. THE TROF WILL APPROACH THE AREA EARLY THURSDAY AND LINGER THROUGH THE WEEKEND AND INTO MONDAY. THE HPC SURFACE ANALYSIS CHARTS INDICATE A WEAK COLD FRONT MOVING IN FROM THE NORTH ON WEDNESDAY AND MOVING INTO THE CWFA LATE IN THE DAY FRIDAY. THIS FRONT LOOKS TO STALL OVER THE PIEDMONT OF THE CAROLINAS AND BRING AN INCREASED CHANCE OF PRECIPITATION STARTING THURSDAY AND CONTINUING THROUGH THE WEEKEND. THE MOUNTAINS WILL TEND TO SEE THE BEST CHANCE FOR PRECIPITATION EARLIER IN THE PERIOD WHILE THE UPSTATE STANDS TO SEE A BETTER CHANCE OVER THE WEEKEND. TEMPERATURES WILL TEND TO BE ABOVE AVERAGE BY 5-10 DEGREES ON WEDNESDAY AND THURSDAY AND DROP BACK DOWN TO NORMAL AS THE FRONT STALLS ACROSS THE AREA ON FRIDAY AND INTO THE WEEKEND. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... DRY AND STABLE AIR MASS ACROSS CWA WILL SUPPORT ONLY SCATTERED CUMULUS NEAR 5K FT DURING THE REMAINDER OF THE AFTERNOON. CUMULUS WILL DISSIPATE BY 00Z WITH LOSS OF DAYTIME HEATING. DURING OVERNIGHT PERIOD... EXPECT ONLY SCATTERED CIRRUS WITH GENERALLY VFR VISIBILITY. AFTER 09Z SOME MVFR VISIBILITY IN FOG AND HAZE IS POSSIBLE. LIGHT SOUTHWEST WIND FLOW AHEAD OF APPROACHING COLD FRONT WILL PUT DAMPER ON POSSIBILITY OF WIDESPREAD MVFR OR IFR FOG 12Z TO 15Z... INCREASING MOISTURE AHEAD OF FRONT WILL LEAD TO POSSIBILITY OF SHOWERS OR THUNDERSTORMS VICINITY AVL. OUTLOOK...COLD FRONT WILL MOVE THROUGH THE AREA BY SUNDAY MORNING FOLLOWED BY HIGH PRESSURE AND MOSTLY VFR WEATHER SUNDAY THROUGH MONDAY. ISOLATED THUNDERSTORMS ARE POSSIBLE IN THE MOUNTAINS TUESDAY AND ACROSS THE CWA ON WEDNESDAY. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...JAT NEAR TERM...LGL SHORT TERM...ARK LONG TERM...ARK/JMS AVIATION...LGL sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 752 PM CDT SAT AUG 2 2008 .UPDATE... VFR LOW CLOUDS ARE EXPECTED TO BREAK UP BEHIND EXITING SHORT WAVE ACROSS NORTHEAST SOUTH DAKOTA AND WEST CENTRAL MINNESOTA THROUGH MIDNIGHT. NEXT SHORT WAVE WILL BE AFFECTING THE REGION AFTER MIDNIGHT INTO SUNDAY MORNING. THE NAM...GFS...AND RUC ALL POINT TO THE CONVECTION IN MT COMING ACROSS THE NORTHERN PART OF THE REGION LATER TONIGHT AND SUNDAY MORNING. THE NAM WAS THE FURTHEREST SOUTH WHERE THE CAP WAS THE STRONGEST. WILL HAVE TO WAIT AND SEE. TOOK OUT POPS FOR THIS EVENING AND MAY HAVE TO ADJUST POPS FOR AFTER MIDNIGHT A LITTLE YET. && .PREV DISCUSSION... .SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT FORECAST CHALLENGES INCLUDE CONVECTION TONIGHT THROUGH SUNDAY NIGHT AND HIGH TEMPERATURES SUNDAY UNDER CLOUD COVER. CURRENTLY...A TROF AXIS SITS ACROSS THE FAR WESTERN FORECAST AREA WITH PLENTY OF LOW LEVEL MOISTURE/INSTABILITY AROUND. THE CAP AT 700HPA IS FORECAST TO UNDERGO CAA THIS EVENING...WITH TEMPS COOLING FROM AROUND +17C TO +13C...WHICH WOULD LIKELY BE ENOUGH COOLING ALOFT TO ALLOW FOR ISOLATED TO WIDELY SCATTERED SUPER CELLULAR THUNDERSTORMS TO DEVELOP WITHIN THE TROF AXIS. THERE IS ALSO 700HPA WARM AIR ADVECTION AND 850HPA MOISTURE ADVECTION ONGOING ACROSS THE EASTERN CWA INTO THIS EVENING. WHEN THE LOW LEVEL JET CATCHES UP TO IT...THE NOSE OF THE LL MAY HELP INDUCE ISOLATED TO WIDELY SCATTERED ELEVATED SUPER CELLULAR THUNDERSTORMS ACROSS THE EASTERN THIRD OF FORECAST ZONES LATE THIS EVENING BEFORE THEY MOVE OFF INTO MINNESOTA. HAVE INSERTED T+RE+ MENTION FOR THESE TO POSSIBLE SCENARIOS AT OPPOSITE ENDS OF THE FORECAST AREA. WILL ALSO HAVE TO KEEP AN EYE ON THE CONVECTION OVER NORTH DAKOTA THAT NOW APPEARS TO BE TRYING TO BUILD SOUTHWARD ALONG THE LEADING EDGE OF 700HPA WAA. LATE TONIGHT ANOTHER MID-LEVEL IMPULSE OF LOW PRESSURE WILL MOVE OUT ONTO THE NORTHERN HIGH PLAINS. LOW LEVEL RESPONSE WILL BE A SURFACE LOW DEEPENING OVER SE MONTANA/NW SOUTH DAKOTA WITH 850HPA MOISTURE ADVECTION AND BACKING LOW LEVEL WINDS POINTING RIGHT INTO EXPECTED THUNDERSTORM CLUSTER THAT WILL BE WORKING WED INTO THE DAKOTAS. EXPECTING THIS STORM CLUSTER TO LATCH ONTO INSTABILITY GRADIENT AT 850HPA OVER THIS CWA AND WHERE THE BEST LOW LEVEL JET SUPPORT SETS UP...RUMBLING EASTWARD OVERNIGHT INTO SUNDAY MORNING. T+RE+ MENTION FOR LATE TONIGHT INSERTED INTO CENTRAL SOUTH DAKOTA ZONES WHERE 20 TO 40 POPS WERE INTRODUCED WITH THIS PACKAGE TO COVER POTENTIAL CONVECTION LATE TONIGHT. ONCE THE MCS DISSIPATES/PUSHES EAST INTO MN...WILL WATCH THE LOW LEVELS RESET ONCE AGAIN WITH LIKELY A REPEAT PERFORMANCE SUNDAY NIGHT INTO MONDAY MORNING. NO SEVERE MENTION AS OF YET...THOUGH...IN THE GRIDS FOR SUNDAY NIGHT. UNDERCUTTING NUMERICAL GUIDANCE HAS BEEN QUITE SUCCESSFUL TODAY. JAMES RIVER VALLEY SOCKED IN WITH STRATUS CLOUDS ALONG THE LEADING EDGE OF 850HPA MOIST TONGUE SLOWLY ADVECTING EAST...AND JUST NEVER FULLY DISSIPATED TODAY. AS SUCH...DID NOT SEE TRUE MAX T POTENTIAL OF MID/UPPER 80S ACHIEVED ACROSS SAID AREA. WITH CONVECTIVE DEBRIS CLOUDS EXPECTED TO BE AROUND DURING THE DAY ON SUNDAY AND SLIGHTLY COOLER 850HPA TEMPS TO MIX OUT ON AN ENE BOUNDARY LAYER WIND...EXPECTING HIGHS ON SUNDAY TO BE AROUND 3 TO 5 DEGREES COOLER THAN TODAY. .LONG TERM...MONDAY THROUGH SATURDAY MODELS CONTINUE IN GOOD AGREEMENT IN OVERALL PATTERN CHANGE FOR THIS WEEK. WITH ZONAL FLOW ACROSS THE CWA TRANSITIONING TO NORTHWEST FLOW AS FAIRLY STRONG TROF DIGS INTO THE EASTERN CONUS...AND WESTERN CONUS RIDGE REESTABLISHES. THIS PATTERN WILL ALLOW FOR COOLER AND DRIER AIR TO FILTER SOUTH OUT OF CANADA AND INTO THE CWA...AND ALLOW FOR NEAR TO BELOW NORMAL TEMPERATURES THROUGH THE LASTER HALF OF THE WORK WEEK. AS FOR PRECIPITATION CHANCES...BEST OPPORTUNITY IS EARLY IN PERIOD WITH ZONAL FLOW ALOFT AND SERIES OF SHORTWAVES SKIRTING THE DAKOTAS. HAVE ADDED ADDITIONAL CHANCE FOR PRECIPITATION IN SOUTH CENTRAL SOUTH DAKOTA AS BACKDOOR FRONT REINFORCES AN EARLIER CANADIAN AIRMASS UNDERGOING MODIFICATION. && .AVIATION... VFR SKIES AND VISIBILITIES ARE EXPECTED TO CONTINUE THROUGH THE NIGHT AND DAY SUNDAY. ANOTHER UPPER LEVEL SHORT WAVE WILL BE AFFECTING THE REGION LATER TONIGHT AND SUNDAY FROM THE WEST. WE MAY SEE SOME TSRAS DEVELOP OUT ACROSS THE WEST AND MOVE ACROSS THE NORTHERN PART OF THE REGION. AT THIS POINT...DONT FORESEE ANY TSRAS OR VICINITY THUNDER OCCURRING AT ANY ONE OF THE TAF STIES. WILL WATCH AND AMEND IF NECESSARY. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...MOHR SHORT TERM...DORN LONG TERM...CONNELLY AVIATION...MOHR WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ABERDEEN SD 1058 AM CDT SAT AUG 2 2008 .UPDATE... MAX TEMP FORECAST FOR TODAY LOOKS AOK. DID DRAG THE ISO SHRA/TSRA 20 POP FURTHER EAST TO MY EASTERN CWA BORDER FROM BETWEEN 15Z AND 20Z AS THESE ELEVATED SHOWERS AND STORMS /WHICH ARE PRODUCING MOSTLY VIRGA WITH CG LIGHTNING/ ARE EXPECTED TO HOLD TOGETHER DUE TO FAVORABLE 250HPA JET MAX POSITIONING OVERHEAD WORKING IN CONJUNCTION WITH ONGOING STRONG 700HPA WARM AIR ADVECTION AND NOTABLE 850HPA MOISTURE ADVECTION. THE 30 TO 40 KNOT LLJ OVERHEAD THIS MORNING WILL WEAKEN SOME INTO THE AFTERNOON...AS LOW STRATUS AND MID CLOUDS MIX OUT AND WORK EAST INTO MINNESOTA ALLOWING STRONGER/DEEPER BOUNDARY LAYER MIXING TO TAP THE LOW LEVEL JET WINDS AND MIX THEM DOWN TO THE SURFACE THIS AFTERNOON. AS SUCH...RAMPED UP SURFACE WINDSPEEDS TO WINDY CATEGORY ACROSS THE EASTERN ZONES FOR THIS AFTERNOON. && .PREV DISCUSSION... .SHORT TERM...TODAY THROUGH MONDAY UPPER LEVEL RIDGE IS CENTERED OVER THE NORTHERN PLAINS EARLY THIS MORNING WITH CONVECTIVE COMPLEX RIDING UP AND AROUND THE RIDGE/CAP INTO WESTERN AND NORTHERN NORTH DAKOTA. LLJ IS IN PLACE FROM ABOUT THE JAMES VALLEY WEST...WITH AN ACCAS FIELD DEVELOPING ACROSS WESTERN SD. VERY WEAK ECHOES NOTED ON KUNR RADAR WITH A FEW LIGHTNING STRIKES. 06Z NAM CATCHING ON TO THIS SOMEWHAT AND TRIES TO SHOW A FEW LIGHT SHOWERS TRACKING NORTHEAST INTO PARTS OF THE NORTHWESTERN CWA. WILL THEREFORE ADD SLIGHT CHANCE POPS ACROSS THIS AREA THROUGH MID MORNING. WILL BE HARD TO GET ANYTHING GOING WITH RUC SHOWING 700 MB TEMPS FROM 15-17 C. WARM AIR ALOFT WILL CONTINUE TO SPREAD NORTHEAST INTO THE CWA TODAY AS SURFACE HIGH PRESSURE MOVES TOWARDS THE GREAT LAKES. SURFACE TROUGH WILL MOVE INTO THE WESTERN DAKOTAS LATER TODAY BUT IT APPEARS CAP WILL BE STRONG ENOUGH TO KEEP A LID ON ANY THUNDERSTORMS DURING THE AFTERNOON. WINDY CONDITIONS WILL DEVELOP TODAY AS PRESSURE GRADIENT IS RATHER TIGHT...ESPECIALLY ACROSS THE EASTERN CWA. WINDS WILL STAY BELOW ADVISORY CRITERIA THOUGH. WILL BE WATCHING FOR TWO AREAS OF POSSIBLE CONVECTION LATE TONIGHT AND INTO SUNDAY MORNING. ONE AREA WILL BE ACROSS EXTREME EASTERN SOUTH DAKOTA AND INTO THE SOUTHERN HALF OF MINNESOTA ON THE NOSE OF DEVELOPING SOUTHWESTERLY LLJ OVERNIGHT. DID KEEP MENTION OF SLIGHT CHANCE POPS GOING ACROSS THE FAR EAST AS MODELS CONTINUE TO SUGGEST BETTER CHANCES OVER MINNESOTA WHERE BEST LLJ PLACEMENT RESIDES. ANOTHER AREA FOR CONVECTION WILL BE ACROSS NORTHWESTERN SOUTH DAKOTA INTO SOUTHERN MINNESOTA AS A RIPPLE AT 500 MB MOVES ACROSS THE AREA ON THE EDGE OF THE CAP. HAVE INCREASED POPS SLIGHTLY ACROSS THE NORTHWESTERN CWA AS MODELS HAVE BEEN IN FAIRLY GOOD AGREEMENT WITH THIS SCENARIO. THIS AREA OF PRECIP WILL MOVE ACROSS NORTH DAKOTA ON SUNDAY AND POTENTIAL EXISTS FOR NORTHERN SOUTH DAKOTA TO CATCH THE FAR SOUTHERN END OF THIS ACTIVITY...ON THE EDGE OF THE CAP. WILL THEREFORE KEEP SLIGHT CHANCE POPS GOING ACROSS EXTREME NORTHERN PORTIONS OF THE CWA FOR SUNDAY. SLIGHTLY BETTER CHANCES FOR PRECIP SUNDAY NIGHT AND MONDAY AS SFC FRONTAL BOUNDARY SHIFTS SOUTH AND UPPER LEVEL RIDGE BREAKS A BIT...ALLOWING FOR MID LEVEL TEMPS TO COOL...STILL ONLY LOOKING AT 30 POPS THOUGH FOR RIGHT NOW. AS FOR TEMPERATURES...CONTINUED TO UNDERCUT MAV GUIDANCE BY A FEW DEGREES IN THIS WARM PATTERN AS MAV HAS BEEN OVERDOING TEMPS THE PAST FEW DAYS. .LONG TERM...MONDAY NIGHT THROUGH FRIDAY AGAIN TNT 00Z MODELS ARE IN FAIR AGREEMENT ON LONG WAVE PATTERN. MID LEVEL RIDGE BEGINS REASSERTING ITSELF OVER THE ROCKIES WHILE FAIRLY STRONG TROF DIGS INTO THE EASTERN CONUS. LIKE WAS MENTIONED IN YESTERDAYS DISCUSSION...THIS POSITIVE PNA LIKE PATTERN SHOULD ALLOW FOR COOLER AND DRIER AIR TO FILTER SOUTH OUT OF CANADA AND INTO THE CWA. AND THIS IS WELL REFLECTED IN THE FORECAST. THE ECMWF EVEN SUGGESTS COOLER TEMPS VS THE GFS. IN ANY EVENT...NEAR TO BELOW NORMAL TEMPERATURES LOOK LIKELY THROUGH THE LAST HALF OF THE MEDIUM RANGE PERIOD WITH LOWER THAN CLIMATOLOGY CHANCES FOR MEASURABLE PCPN. && .AVIATION... 15Z TAF UPDATE FOR KABR...KATY...KPIR AND KMBG TERMINALS FOR THE MOST PART VFR CONDITIONS ARE EXPECTED AT ALL TERMINALS THROUGH TODAY AND TNT. HOWEVER...WILL NEED TO KEEP AN EYE ON EXPANDING AREA OF MVFR STRATUS OVER THIS STATE. BKN-OVC 1500 TO 2500FT AGL STRATUS LAYER IS DEVELOPING...AND WILL POTENTIALLY IMPACT FLYING WEATHER AT ALL FOUR TERMINALS THROUGH EARLY THIS AFTERNOON...BEFORE DAYTIME HEATING/MIXING HAS A CHANCE TO BREAK IT UP. ONE OTHER CONCERN IS THE ELEVATED ISOLATED SHOWERS AND THUNDERSTORMS WORKING EAST ACROSS THE STATE THIS MORNING. MOST CONVECTION IS SO WEAK AND SO ELEVATED THAT NO PRECIPITATION IS REACHING THE GROUND. SOME CELLS HAVE BEEN PRODUCING LIGHTNING...THOUGH. KABR AND KATY TERMINALS ARE UNDER THE GUN TO EXPERIENCE THESE ELEVATED SHOWERS/STORMS THROUGH AROUND 19Z THIS AFTERNOON. OTHERWISE...WILL NEED TO WAIT UNTIL LATER TONIGHT /AT OR AFTER 03Z/ TO SEE THE NEXT CHANCES OF TSRA ACROSS EXTREME EASTERN SOUTH DAKOTA /KATY TERMINAL/ AND ACROSS CENTRAL AND NORTH CENTRAL SOUTH DAKOTA /KPIR AND KMBG TERMINALS/. ALSO...EXPECT SOUTH BREEZES ACROSS CENTRAL AND NORTH CENTRAL SOUTH DAKOTA TO PERSIST TODAY...WITH OCCASIONAL HIGHER GUSTS AS STRONGER WINDS MIX DOWN TO THE SURFACE THIS MORNING AND AFTERNOON. FURTHER EAST AT THE KABR AND KATY TERMINALS...THE BREEZY TO WINDY SOUTHERLY SURFACE WINDS DO NOT LOOK TO REALLY GET GOING UNTIL EARLY THIS AFTERNOON...ONCE THE LOW STRATUS HAS BEEN MIXED OUT. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...DORN SHORT TERM...TMT LONG TERM...TDK AVIATION...DORN WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 424 AM CDT SAT AUG 2 2008 .SHORT TERM...TODAY THROUGH MONDAY UPPER LEVEL RIDGE IS CENTERED OVER THE NORTHERN PLAINS EARLY THIS MORNING WITH CONVECTIVE COMPLEX RIDING UP AND AROUND THE RIDGE/CAP INTO WESTERN AND NORTHERN NORTH DAKOTA. LLJ IS IN PLACE FROM ABOUT THE JAMES VALLEY WEST...WITH AN ACCAS FIELD DEVELOPING ACROSS WESTERN SD. VERY WEAK ECHOES NOTED ON KUNR RADAR WITH A FEW LIGHTNING STRIKES. 06Z NAM CATCHING ON TO THIS SOMEWHAT AND TRIES TO SHOW A FEW LIGHT SHOWERS TRACKING NORTHEAST INTO PARTS OF THE NORTHWESTERN CWA. WILL THEREFORE ADD SLIGHT CHANCE POPS ACROSS THIS AREA THROUGH MID MORNING. WILL BE HARD TO GET ANYTHING GOING WITH RUC SHOWING 700 MB TEMPS FROM 15-17 C. WARM AIR ALOFT WILL CONTINUE TO SPREAD NORTHEAST INTO THE CWA TODAY AS SURFACE HIGH PRESSURE MOVES TOWARDS THE GREAT LAKES. SURFACE TROUGH WILL MOVE INTO THE WESTERN DAKOTAS LATER TODAY BUT IT APPEARS CAP WILL BE STRONG ENOUGH TO KEEP A LID ON ANY THUNDERSTORMS DURING THE AFTERNOON. WINDY CONDITIONS WILL DEVELOP TODAY AS PRESSURE GRADIENT IS RATHER TIGHT...ESPECIALLY ACROSS THE EASTERN CWA. WINDS WILL STAY BELOW ADVISORY CRITERIA THOUGH. WILL BE WATCHING FOR TWO AREAS OF POSSIBLE CONVECTION LATE TONIGHT AND INTO SUNDAY MORNING. ONE AREA WILL BE ACROSS EXTREME EASTERN SOUTH DAKOTA AND INTO THE SOUTHERN HALF OF MINNESOTA ON THE NOSE OF DEVELOPING SOUTHWESTERLY LLJ OVERNIGHT. DID KEEP MENTION OF SLIGHT CHANCE POPS GOING ACROSS THE FAR EAST AS MODELS CONTINUE TO SUGGEST BETTER CHANCES OVER MINNESOTA WHERE BEST LLJ PLACEMENT RESIDES. ANOTHER AREA FOR CONVECTION WILL BE ACROSS NORTHWESTERN SOUTH DAKOTA INTO SOUTHERN MINNESOTA AS A RIPPLE AT 500 MB MOVES ACROSS THE AREA ON THE EDGE OF THE CAP. HAVE INCREASED POPS SLIGHTLY ACROSS THE NORTHWESTERN CWA AS MODELS HAVE BEEN IN FAIRLY GOOD AGREEMENT WITH THIS SCENARIO. THIS AREA OF PRECIP WILL MOVE ACROSS NORTH DAKOTA ON SUNDAY AND POTENTIAL EXISTS FOR NORTHERN SOUTH DAKOTA TO CATCH THE FAR SOUTHERN END OF THIS ACTIVITY...ON THE EDGE OF THE CAP. WILL THEREFORE KEEP SLIGHT CHANCE POPS GOING ACROSS EXTREME NORTHERN PORTIONS OF THE CWA FOR SUNDAY. SLIGHTLY BETTER CHANCES FOR PRECIP SUNDAY NIGHT AND MONDAY AS SFC FRONTAL BOUNDARY SHIFTS SOUTH AND UPPER LEVEL RIDGE BREAKS A BIT...ALLOWING FOR MID LEVEL TEMPS TO COOL...STILL ONLY LOOKING AT 30 POPS THOUGH FOR RIGHT NOW. AS FOR TEMPERATURES...CONTINUED TO UNDERCUT MAV GUIDANCE BY A FEW DEGREES IN THIS WARM PATTERN AS MAV HAS BEEN OVERDOING TEMPS THE PAST FEW DAYS. .LONG TERM...MONDAY NIGHT THROUGH FRIDAY AGAIN TNT 00Z MODELS ARE IN FAIR AGREEMENT ON LONG WAVE PATTERN. MID LEVEL RIDGE BEGINS REASSERTING ITSELF OVER THE ROCKIES WHILE FAIRLY STRONG TROF DIGS INTO THE EASTERN CONUS. LIKE WAS MENTIONED IN YESTERDAYS DISCUSSION...THIS POSITIVE PNA LIKE PATTERN SHOULD ALLOW FOR COOLER AND DRIER AIR TO FILTER SOUTH OUT OF CANADA AND INTO THE CWA. AND THIS IS WELL REFLECTED IN THE FORECAST. THE ECMWF EVEN SUGGESTS COOLER TEMPS VS THE GFS. IN ANY EVENT...NEAR TO BELOW NORMAL TEMPERATURES LOOK LIKELY THROUGH THE LAST HALF OF THE MEDIUM RANGE PERIOD WITH LOWER THAN CLIMATOLOGY CHANCES FOR MEASURABLE PCPN. && .AVIATION... FOR THE MOST PART VFR CONDITIONS ARE EXPECTED AT ALL TERMINALS THROUGH TODAY AND TNT. HOWEVER...WILL NEED TO KEEP AN EYE ON EXPANDING AREA OF STRATUS OVER NEBRASKA. THIS AREA MAY LIFT INTO THE MO RIVER VALLEY THIS MORNING. BUT AT THIS TIME EXPECT THAT DAYTIME HEATING WILL EAT AWAY AT THAT DECK...LEAVING SOME CUMULUS OR STRATOCUMULUS AOA 3K FEET FOR THE MORNING AND AFTERNOON HOURS ACROSS BOTH THE MO AND JAMES RIVER VALLEYS. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ SHORT TERM...TMT LONG TERM...TDK AVIATION...TDK WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 255 PM MDT FRI AUG 1 2008 .DISCUSSION...LATEST SURFACE ANALYSIS CONTINUES TO SHOW A DRY LINE STRETCHING FROM HULETT WY SOUTH ALONG THE WESTERN EDGE OF THE BLACK HILLS AND INTO EAST CENTRAL WYOMING. SOUTH/SOUTHEASTERLY RETURN FLOW CONTINUES EAST OF THE DRYLINE ACROSS WESTERN SOUTH DAKOTA WITH DEWPOINTS IN THE LOWER 60S. WATER VAPOR SHOWS A SHORTWAVE NOW OVER NORTH CENTRAL WYOMING APPROACHING THE CWA. NAM/RUC BOTH CONTINUE SHOW SBCAPE VALUES OF 1500 TO 2500 J/KG THIS AFTERNOON ACROSS FAR WESTERN SOUTH DAKOTA INCLUDING THE BLACK HILLS. BIG QUESTION REMAINS WHETHER THERE IS SUFFICIENT HEATING TO BREAK THE CAP AND TAP INTO THE INSTABILITY. VIS SAT SHOWS VERY MINIMAL CU DEVELOPMENT EVEN OVER THE BLACK HILLS...SO HAVE REDUCED POPS TO 10 WITH MENTION OF A SLIGHT CHANCE OF THUNDERSTORMS IN CASE ONE OR TWO STORMS DO MANAGE TO DEVELOP. MODELS SHOW ANOTHER WAVE MOVING ACROSS THE MONTANA/NORTH DAKOTA BORDER LATE TONIGHT. THIS WILL DEVELOP A SURFACE LOW ACROSS EASTERN MONTANA AND SWEEP A COLD FRONT THROUGH THE AREA LATE TONIGHT AND TOMORROW MORNING. THIS MAY BRING AN ISOLATED STORM TO FAR NORTHWEST SOUTH DAKOTA AFTER MIDNIGHT...BUT CHANCES REMAIN LOW CONSIDERING THE LACK OF MOISTURE IN THE LOW LEVELS. THE COLD FRONT WILL CROSS THE AREA TOMORROW WITH DRIER NORTHERLY FLOW BEHIND THE FRONT. WITH 700 MB TEMPS OF 14-18C...A VERY WARM DAY IS EXPECTED WITH MOST LOCATIONS ACROSS THE PLAINS REACHING 95 TO 100 DEGREES. FORECAST SOUNDINGS SHOW THE DRIER AIR WILL HAVE A HARDER TIME BREAKING THE CAP...BUT THE HILLS MAY STILL SEE ONE OR TWO STORMS IN THE AFTERNOON. ZONAL FLOW ALOFT WILL CONTINUE ACROSS THE CWA SATURDAY INTO SUNDAY. LOW PRESSURE WILL DEVELOP ALONG A BAROCLINIC ZONE NEAR THE CENTRAL NEBRASKA/SD BORDER. THERE MAY BE ENOUGH OF AN EASTERLY COMPONENT TO THE WIND TO ALLOW MORE MOIST AIR BACK ACROSS NORTHWEST SOUTH DAKOTA. IF THIS HAPPENS...THERE WILL BE PLENTY OF INSTABILITY AND A WEAKER CAP ACROSS THE NORTHERN HALF OF THE CWA. WITH WAVES CROSSING THE AREA AND PLENTY OF SHEAR ACROSS THE NORTH...THERE IS A POSSIBILITY FOR SEVERE STORMS MAINLY LATER TOWARD THE EVENING HOURS. EXTENDED...FLAT UPPER RIDGE WILL DOMINATE THE WEATHER EARLY NEXT WEEK WITH AMPLIFICATION OF THE UPPER RIDGE OVER WESTERN NORTH AMERICAN FOR THE MIDDLE AND END OF THE WEEK. THE RESULT WILL BE SMALL CHANCES FOR TSRA EACH DAY...AS WEAK WAVES MOVE WITH THE MAIN JET ALONG THE US/CANADIAN BORDER. TEMPERATURES WILL BE NEAR NORMAL. && .AVIATION...VFR CONDITIONS WILL DOMINATE TONIGHT. ANY ISOLATED TSRA THAT DEVELOP MAY HAVE LOCAL MVFR CONDITIONS AND GUSTY ERRATIC WINDS. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. && $$ CALDERON/HELGESON sd AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 1100 AM MDT FRI AUG 1 2008 .DISCUSSION...LATEST SURFACE ANALYSIS SHOWS A DRY LINE STRETCHING FROM HULETT WY SOUTH ALONG THE WESTERN EDGE OF THE BLACK HILLS AND INTO EAST CENTRAL WYOMING. SOUTH/SOUTHEASTERLY RETURN FLOW CONTINUES EAST OF THE DRYLINE ACROSS WESTERN SOUTH DAKOTA WITH DEWPOINTS IN THE LOWER 60S. WATER VAPOR SHOWS A SHORTWAVE NOW OVER WESTERN WYOMING APPROACHING THE CWA ARRIVE LATE THIS AFTERNOON/EARLY EVENING. NAM/RUC BOTH SHOW CAPE VALUES OF 1500 TO 2500 J/KG THIS AFTERNOON ACROSS FAR WESTERN SOUTH DAKOTA INCLUDING THE BLACK HILLS WITH SIGNIFICANT WEAKENING OF THE CAP. QUESTION IS WHETHER THE CAP WILL BE BROKEN OR NOT. THIS DOES SEEM MOST LIKELY TO OCCUR OVER THE BLACK HILLS...SO HAVE LEFT CHANCE POPS THERE. HAVE ADDED SLIGHT CHANCE POPS TO THE REST OF THE SOUTH DAKOTA PLAINS WEST OF A LINE FROM FAITH TO PINE RIDGE WHERE MODELS SUGGEST THE CAP WILL HOLD STRONG TODAY. REST OF THE FORECAST IS IN GOOD SHAPE. && .PREV DISCUSSION [200 AM MDT]...AT 08Z SFC MAP SHOWS CLEAR SKIES WITH HIGH PRES OVER CENTRAL PLAINS AS S-SE SFC RETURN FLOW DEVELOPING ACRS AREA. ALOFT...FLAT UPPER RIDGE CONTINUES TO DOMINATE WX ACRS NRN PLAINS. TODAY/TONIGHT...S-SE FLOW WILL DVLP ACRS WRN SD ON BACKSIDE OF SFC HIGH PRES WITH INCREASING MSTR AND INSTABILITY ACRS REGION...700MB TEMPS WILL ALSO INCREASE QUITE A BIT PRODUCING A FORMIDABLE CAP. BEST INSTABILITY AND ML CAPE FM 1000-2000 J/KG WL BE OVER FAR WRN SD AND THE BLK HILLS...WHERE CAP WILL BE WEAKEST. THIS MAY COMBINE WITH WK MID LVL S/W TO PRODUCE SOME SCT TSTMS THIS AFT/EARLY THIS EVENING ACRS BLACK HILLS. TEMPS WL BE ABV NORMAL WITH MOST AREAS WELL INTO 90S AND A FEW PLACES ON SD PLAINS WILL PUSH 100. LATER TONIGHT S/W MVG ACRS ERN MT/WRN ND MAY KICK OFF A TSTM OR TWO ACRS NWRN SD...THOUGH BEST CHANCES WILL BE NORTH OF FA. SAT/SAT NIGHT...SFC CDFNT WILL BE OVR FAR WRN SD AT 12Z SAT AND PUSH ACRS FA DURING DAY...BEST INSTABILITY AND MSTR WILL BE AHEAD OF CDFNT...BUT AGAIN STRONG CAP SHOULD INHIBIT ANY CONVECTION. WL CONT LOW CHANCE POPS IN BLACK HILLS WHERE ISOLD TSTM MAY BREAK THROUGH CAP. MAY SEE A TSTM OR TWO IN NWRN SD SAT NIGHT AS AGAIN EXPECT ACTIVITY TO NORTH OF FA IN ERN MT/WRN ND. ON SUNDAY...RIDGE WILL CONT TO DOMINATE WX WITH TEMPS AGAIN WELL INTO 90S TO NEAR 100. SHOULD BE ANOTHER DRY DAY. MAY SEE SOME TSTMS SUNDAY NIGHT AS NEXT SYSTEM APPROACHES FROM THE WEST. EXTENDED...UPPER RIDGE WILL FLATTEN OUT FOR THE FIRST PART OF THE WORK WEEK AS A VARIETY OF WEAK SHORT WAVES SLIDE THROUGH. THIS WILL BRING A CHANCE OF THUNDERSTORMS...ALONG WITH COOLER TEMPERATURES TO THE AREA. && .AVIATION...ISOLD/SCT -TSRA WILL BE POSSIBLE OVER THE BLACK HILLS AND FAR WESTERN SOUTH DAKOTA THIS AFTERNOON...AND INTO FAR NE WYO AND PARTS OF FAR WRN SD THIS EVE. OTHERWISE...VFR CONDITIONS WILL CONTINUE. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. && $$ CALDERON sd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ABERDEEN SD 1101 AM CDT FRI AUG 1 2008 .UPDATE... ONLY CHANGE MADE TO THE TODAY PERIOD WAS TO INSERT A SLIGHT CHANCE OF THUNDER ACROSS THE SWRN THIRD OF FORECAST ZONES TO COVER ANY OF THIS WEAK ELEVATED CONVECTION STILL TRYING TO DEVELOP ON THE NOSE OF THE WANING LOW LEVEL JET WHERE 850HPA MOISTURE ADVECTION IS JUXTAPOSED WITH 700HPA THETA-E RIDGING IN PLACE ACROSS THE WESTERN HALF OF SOUTH DAKOTA. MAX TEMPERATURE FORECAST FOR TODAY LOOKS GOOD. && .PREV DISCUSSION... .SHORT TERM...TODAY THROUGH SUNDAY HIGH PRESSURE IS IN CONTROL THIS MORNING WITH CLEAR SKIES AND LIGHT WINDS OVER THE ENTIRE CWA. DEWPOINTS HAVE BEEN STAYING UP IN THE UPPER 50S TO LOW 60S ACROSS EASTERN SOUTH DAKOTA WHICH HAS LED TO PATCHY FOG ACROSS SOUTHEASTERN SD. NO OBS ACROSS THE ABR CWA HAVE SEEN BR/FG YET BUT WITH RUC SOUNDINGS SHOWING A WEAK INVERSION NEAR THE SURFACE AND WINDS REMAINING LIGHT WITH HIGHER DEWPOINTS...STILL CANNOT RULE OUT PATCHY FOG ACROSS PARTS OF THE NORTHEASTERN CWA THIS MORNING. WILL KEEP PATCHY FOG IN THE GRIDS THROUGH THE EARLY MORNING HOURS. HIGH PRESSURE WILL REMAIN OVER THE EASTERN DAKOTAS AND MINNESOTA TODAY SO EXPECTING MOSTLY SUNNY SKIES AND A LIGHT SOUTHEAST BREEZE ACROSS THE EASTERN CWA. A BIT MORE BREEZY ACROSS CENTRAL SD TODAY WHERE PRESSURE GRADIENT IS TIGHTER. HIGH PRESSURE MOVES EAST OVERNIGHT AND LLJ DEVELOPS ACROSS CENTRAL/WESTERN SOUTH DAKOTA. AN EXAMINATION OF POINT SOUNDINGS ACROSS THE AREA REVEAL SMALL AMOUNTS OF MOISTURE RETURNING AT MID LEVELS...AS WELL AS ELEVATED INSTABILITY. HAS NOT BEEN HARD THIS SUMMER TO GET ACCUS DEVELOPING INTO LIGHT THUNDERSHOWERS WITH THIS SETUP SO WILL KEEP PREVIOUS MENTION OF SLIGHT CHANCE POPS IN THE FORECAST. ALTHOUGH HAVE ADJUSTED AREA JUST A BIT TO ACCOUNT FOR AREAS OF BEST ELEVATED INSTABILITY AND MOISTURE. KEPT THINGS CONFINED TO THE CWA BORDER NEAR FSD AS POINTS FARTHER NORTH THAN THIS SHOW VIRTUALLY NO MOISTURE AND ELEVATED INSTABILITY. HEADING INTO SATURDAY MID LEVEL TEMPERATURES REALLY BEGIN TO INCREASE AS 700 MB TEMPS SOAR INTO THE MID TO UPPER TEENS. SURFACE LOW PRESSURE ALSO BEGINS TO TAKE SHAPE ACROSS THE NORTHERN HIGH PLAINS/NORTHERN ROCKIES. IT APPEARS THE AREA WILL BE CAPPED FROM CONVECTION WITH MOST THE ACTIVITY ACROSS ND. MAY BE ABLE TO GET SOMETHING GOING SATURDAY NIGHT ACROSS THE EXTREME NORTHEASTERN CWA ON THE EDGE OF CAP. SPC HAS THIS AREA IN DAY TWO SLIGHT RISK AND WITH DEVELOPMENT OF SOUTHWESTERLY LLJ SATURDAY NIGHT...COULD SEE MCS DEVELOPMENT SOMEWHERE ACROSS WESTERN MINNESOTA...DIVING SOUTHEAST. WILL KEEP FORECAST DRY AT THIS TIME BUT WILL HAVE TO WATCH FOR SMALL CHANCE POPS ALONG THE EDGE OF CAP. .LONG TERM...SUNDAY NIGHT THROUGH THURSDAY 00Z MODELS ARE IN AMAZING AGREEMENT THIS MORNING...ESPECIALLY NOTEWORTHY CONSIDERING THE SEASON. THE SUNDAY NIGHT THROUGH MONDAY NIGHT TIME PERIOD SHOULD FEATURE SOME ACTIVE WEATHER AS MID LEVEL PATTERN UNDERGOES CHANGES. ENERGY COMING ACROSS THE NORTHERN ROCKIES FLATTENS MID LEVEL RIDGING OVER THE REGION...AND THEN DIVES TOWARD THE OHIO VALLEY AS RIDGE SHARPENS OVER THE ROCKIES. PREDICTED MID LEVEL LONG WAVE PATTERN BY 144 HOURS LOOKS SOMEWHAT AMPLIFIED/MERIDIONAL FOR THE TIME OF YEAR. THE FAIRLY DEEP TROF OVER THE EASTERN CONUS SHOULD ALLOW FOR MILD CANADIAN AIR TO FILTER SOUTH OVER THE REGION BEGINNING ON MONDAY AND LASTING THROUGH THE END OF THE WORK WEEK. WOULD NOT BE SURPRISED TO SEE SOME BELOW NORMAL TEMPERATURES DURING THAT TIME PERIOD. ALL IN ALL FAIRLY PLEASANT CONSIDERING ITS THE FIRST OF AUGUST. && .AVIATION... GOOD VFR TO RULE OVER THE NEXT 24 HOURS WITH HIGH PRESSURE IN PLACE ACROSS THE REGION. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...DORN SHORT TERM...TMT LONG TERM...TDK AVIATION...DORN WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 325 AM CDT FRI AUG 1 2008 .SHORT TERM...TODAY THROUGH SUNDAY HIGH PRESSURE IS IN CONTROL THIS MORNING WITH CLEAR SKIES AND LIGHT WINDS OVER THE ENTIRE CWA. DEWPOINTS HAVE BEEN STAYING UP IN THE UPPER 50S TO LOW 60S ACROSS EASTERN SOUTH DAKOTA WHICH HAS LED TO PATCHY FOG ACROSS SOUTHEASTERN SD. NO OBS ACROSS THE ABR CWA HAVE SEEN BR/FG YET BUT WITH RUC SOUNDINGS SHOWING A WEAK INVERSION NEAR THE SURFACE AND WINDS REMAINING LIGHT WITH HIGHER DEWPOINTS...STILL CANNOT RULE OUT PATCHY FOG ACROSS PARTS OF THE NORTHEASTERN CWA THIS MORNING. WILL KEEP PATCHY FOG IN THE GRIDS THROUGH THE EARLY MORNING HOURS. HIGH PRESSURE WILL REMAIN OVER THE EASTERN DAKOTAS AND MINNESOTA TODAY SO EXPECTING MOSTLY SUNNY SKIES AND A LIGHT SOUTHEAST BREEZE ACROSS THE EASTERN CWA. A BIT MORE BREEZY ACROSS CENTRAL SD TODAY WHERE PRESSURE GRADIENT IS TIGHTER. HIGH PRESSURE MOVES EAST OVERNIGHT AND LLJ DEVELOPS ACROSS CENTRAL/WESTERN SOUTH DAKOTA. AN EXAMINATION OF POINT SOUNDINGS ACROSS THE AREA REVEAL SMALL AMOUNTS OF MOISTURE RETURNING AT MID LEVELS...AS WELL AS ELEVATED INSTABILITY. HAS NOT BEEN HARD THIS SUMMER TO GET ACCUS DEVELOPING INTO LIGHT THUNDERSHOWERS WITH THIS SETUP SO WILL KEEP PREVIOUS MENTION OF SLIGHT CHANCE POPS IN THE FORECAST. ALTHOUGH HAVE ADJUSTED AREA JUST A BIT TO ACCOUNT FOR AREAS OF BEST ELEVATED INSTABILITY AND MOISTURE. KEPT THINGS CONFINED TO THE CWA BORDER NEAR FSD AS POINTS FARTHER NORTH THAN THIS SHOW VIRTUALLY NO MOISTURE AND ELEVATED INSTABILITY. HEADING INTO SATURDAY MID LEVEL TEMPERATURES REALLY BEGIN TO INCREASE AS 700 MB TEMPS SOAR INTO THE MID TO UPPER TEENS. SURFACE LOW PRESSURE ALSO BEGINS TO TAKE SHAPE ACROSS THE NORTHERN HIGH PLAINS/NORTHERN ROCKIES. IT APPEARS THE AREA WILL BE CAPPED FROM CONVECTION WITH MOST THE ACTIVITY ACROSS ND. MAY BE ABLE TO GET SOMETHING GOING SATURDAY NIGHT ACROSS THE EXTREME NORTHEASTERN CWA ON THE EDGE OF CAP. SPC HAS THIS AREA IN DAY TWO SLIGHT RISK AND WITH DEVELOPMENT OF SOUTHWESTERLY LLJ SATURDAY NIGHT...COULD SEE MCS DEVELOPMENT SOMEWHERE ACROSS WESTERN MINNESOTA...DIVING SOUTHEAST. WILL KEEP FORECAST DRY AT THIS TIME BUT WILL HAVE TO WATCH FOR SMALL CHANCE POPS ALONG THE EDGE OF CAP. .LONG TERM...SUNDAY NIGHT THROUGH THURSDAY 00Z MODELS ARE IN AMAZING AGREEMENT THIS MORNING...ESPECIALLY NOTEWORTHY CONSIDERING THE SEASON. THE SUNDAY NIGHT THROUGH MONDAY NIGHT TIME PERIOD SHOULD FEATURE SOME ACTIVE WEATHER AS MID LEVEL PATTERN UNDERGOES CHANGES. ENERGY COMING ACROSS THE NORTHERN ROCKIES FLATTENS MID LEVEL RIDGING OVER THE REGION...AND THEN DIVES TOWARD THE OHIO VALLEY AS RIDGE SHARPENS OVER THE ROCKIES. PREDICTED MID LEVEL LONG WAVE PATTERN BY 144 HOURS LOOKS SOMEWHAT AMPLIFIED/MERIDIONAL FOR THE TIME OF YEAR. THE FAIRLY DEEP TROF OVER THE EASTERN CONUS SHOULD ALLOW FOR MILD CANADIAN AIR TO FILTER SOUTH OVER THE REGION BEGINNING ON MONDAY AND LASTING THROUGH THE END OF THE WORK WEEK. WOULD NOT BE SURPRISED TO SEE SOME BELOW NORMAL TEMPERATURES DURING THAT TIME PERIOD. ALL IN ALL FAIRLY PLEASANT CONSIDERING ITS THE FIRST OF AUGUST. && .AVIATION... PATCHY FOG WITH VSBYS BLO 1SM WILL BE POSSIBLE THIS MORNING...ESPECIALLY AT KABR/KATY. OTHERWISE...EXPECT LITTLE IF ANY CLOUDINESS BELOW 10K FEET THROUGH TONIGHT. VSBYS OUTSIDE OF THAT PATCHY MORNING FOG SHOULD BE UNRESTRICTED THROUGH TNT. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ SHORT TERM...TMT LONG TERM...TDK AVIATION...TDK WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 902 PM EDT FRI AUG 1 2008 .DISCUSSION...NO CHANGES. LATEST OPERATIONAL MODEL RUNS SUGGEST SCATTERED CONVECTION CURRENTLY ONGOING OVER OHIO RIVER VALLEY WILL DISSIPATE AS IT APPROACHES OUR FORECAST AREA. HOWEVER...RUC DEPICTS SCATTERED PRECIP REMAINING INTACT OVER THE NORTHEASTERN ZONES TOWARD MORNING AND AM RELUCTANT TO PULL POPS DUE TO THIS UNCERTAINTY. TEMPS APPEAR REASONABLE BASED ON CURRENT TRENDS AND LATEST MODEL GUIDANCE. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 70 93 70 94 70 / 10 20 10 0 0 KNOXVILLE MCGHEE TYSON AIRPORT, TN 68 91 68 92 68 / 20 30 10 0 0 OAK RIDGE, TN 68 92 68 93 68 / 20 30 10 0 0 TRI CITIES AIRPORT, TN 63 89 62 90 62 / 20 40 10 0 0 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ LCM tn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BROWNSVILLE TX 928 AM CDT FRI AUG 1 2008 .DISCUSSION...WATER VAPOR SATELLITE IMAGES AND RUC80 500MB HEIGHT ANALYSIS INDICATED A WEAK LOW AND SHEAR AXIS ACROSS NORTH TEXAS THIS MORNING. A WEAK 500MB RIDGE ACROSS SOUTH TX AND THE WESTERN GULF OF MEXICO SHOULD CONTINUE TO PROVIDE SUBSIDENCE ACROSS DEEP SOUTH TX THIS AFTERNOON. 12Z NAM12 PROGS SOME ISOLATED CONVECTION DEVELOPING ACROSS WESTERN PORTIONS OF THE CWA LATE THIS AFTERNOON BUT WILL KEEP RAIN CHANCES OUT OF THE FORECAST TODAY. WILL MAKE SOME MINOR CHANGES TO MAX TEMPERATURE GRIDS THIS AFTERNOON. OTHERWISE...CURRENT FORECAST GRIDS LOOK O.K. FOR NOW. && .AVIATION...SURFACE OBS SHOWED SOME LIGHT FOG EARLY THIS MORNING WHICH IS EXPECTED TO DIMINISH WITH TIME. SOME SC THIS MORNING MOVING THROUGH HIDALGO, BROOKS AND PORTIONS OF JIM HOGG COUNTIES. THE LOWER RIO GRANDE VALLEY AS WELL AS THE UPPER VALLEY SHOULD FILL IN WITH CU THE REST OF THE MORNING INTO THE AFTERNOON. SCT TO BKN CLOUD DECKS OF MVFR AND ABOVE ARE EXPECTED TODAY. THE TAF SITE FORECASTS LOOK GOOD SO NO CHANGES ARE EXPECTED AT THIS TIME. && .MARINE...AT 8AM BUOY020 REPORTS A SSE WIND AT 10 TO 14 KNOTS WITH SEAS AT 3 TO 4 FEET. MTRPIL REPORTS A SSE WIND AT 6 KNOTS. 500MB RIDGE REMAINS ANCHORED ACROSS THE SOUTHWESTERN U.S. AND THROUGH THE EASTERN GULF INTO THE WESTERN ATLANTIC. HIGH PRESSURE AT THE SURFACE OVER THE CENTRAL GULF WILL INTERACT WITH A TROUGH IN NORTHWESTERN TEXAS TODAY. THIS WILL MAINTAIN A LIGHT TO MODERATE SOUTH TO SOUTHEAST WIND. SEAS ARE ANTICIPATED TO REMAIN IN A 2 TO 4 FOOT RANGE THROUGH THE UPCOMING WEEKEND BEFORE FALLING EARLY NEXT WEEK. EXPECT MARINE CONDITIONS ALONG THE LOWER TX COASTLINE WILL REMAIN BELOW SCA LEVELS. && .PREV DISCUSSION... /ISSUED 228 AM CDT FRI AUG 01 2008/ A HIGH PRESSURE RIDGE EXTENDING INTO THE RIO GRANDE VALLEY COUPLED WITH A LOW PRESSURE SYSTEM LOCATED OVER OKLAHOMA AND NORTHERN TEXAS WILL INCREASE THE WINDS ACROSS DEEP SOUTH TEXAS THIS AFTERNOON AND SATURDAY AFTERNOON. THE WINDS WILL BECOME MODERATE AND GUSTY FROM THE SOUTHEAST. THE PRESSURE GRADIENT WILL RELAX OVER THE CWA BY SUNDAY AND WINDS WILL BECOME LIGHT OVERNIGHT AND MODERATE DURING THE AFTERNOONS AND EARLY EVENINGS SUNDAY THROUGH THE END OF NEXT WEEK. GENERALLY DRY CONDITIONS WITH CLEAR TO PARTLY CLOUDY SKIES WILL PREVAIL OVER DEEP SOUTH TEXAS THROUGH THE END OF THE FORECAST PERIOD. THE TEMPERATURES WILL CONTINUE AT SLIGHTLY HIGHER THAN NORMAL VALUES THROUGHOUT THE FORECAST PERIOD. MARINE...BUOY020 CHECKS IN THIS MORNING WITH A SSE WIND AROUND 14 KTS WITH SWELLS AROUND 3.5 FT. MTRPIL CHECKS IN WITH A SSE WIND AROUND 10 KTS. 500 MB RIDGING WILL REMAIN ANCHORED IN PLACE OVER MUCH OF THE SOUTH CENTRAL PLAINS AND THE SOUTHEASTERN U.S. THIS WILL MAINTAIN A LIGHT TO MODERATE ONSHORE FLOW OVER THE LOWER TX COASTLINE. LATE IN THE CWF PERIOD...BOTH THE ECMWF AND THE GFS SHEAR OFF THE SOUTHERN END OF THE MAJOR 500 MB TROUGH DIGGING OVER THE EAST COAST AND EVENTUALLY SHIFT THIS FEATURE WEST TOWARDS THE TX COASTLINE. BOTH MODELS SHOW MORE OF A MID LEVEL FEATURE WITH NOT MUCH OF A SURFACE FEATURE. WILL SEE HOW FUTURE RUNS OF THE MODELS RESOLVE THIS FEATURE. EXPECT THAT MARINE CONDITIONS ALONG THE LOWER TX COASTLINE WILL REMAIN BELOW SCA LEVELS. AVIATION...11-3.9 MICRON IMAGERY AND SURFACE OBS SHOW SOME PATCHY SC AND FOG FORMING AROUND THE REGION. THESE WILL REDUCE CEILINGS AND VSBYS THROUGHOUT THE EARLY MORNING. THE INCREASING DAYTIME HEATING AND THE STRONGER S-SE SURFACE WINDS WILL MIX OUT THE SC AND FOG LATER THIS AFTERNOON. EXPECT GENERAL VFR CONDITIONS TO PREVAIL FOR THE BULK OF THIS CURRENT TAF PERIOD. && .PRELIMINARY POINT TEMPS/POPS... BAYVIEW/PORT ISABEL 90 79 92 78 / 0 0 0 0 BROWNSVILLE 92 78 95 77 / 0 0 0 0 HARLINGEN 94 78 96 76 / 0 0 0 0 MCALLEN 96 78 98 77 / 0 0 0 0 RIO GRANDE CITY 98 77 100 77 / 0 0 0 0 SOUTH PADRE ISLAND 86 80 88 80 / 0 0 0 0 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT: HTTP://WWW.WEATHER.GOV/BROWNSVILLE PUBLIC/GRIDS...61 AVIATION/MARINE...59/57 MESO/FXC...CAMPBELL/HART tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 938 PM CDT SAT AUG 2 2008 .UPDATE...TRYING TO REVIEW 00Z RAOBS AND LATEST OBSERVATION AND MODEL DATA AND GET A FEEL FOR WHICH IS GOING TO WIN OUT ACROSS IOWA AND SRN MN TONIGHT...WARM AIR ALOFT IN THE 650-850 MB LAYER OR MOISTURE CONVERGENCE AND SATURATION SOMEWHERE IN THAT LAYER AND ELEVATED CONVECTION/TSRA. 01Z PROFILER AND 88D VWP DATA AROUND 850 MB LEVEL HAVE SEEN ABOUT A 5KT INCREASE OVER THE PAST HOUR ACROSS WESTERN IOWA IN A GENERAL S-SWRLY FLOW. THIS FLOW IS CONVERGING WITH A MORE S-SERLY FLOW FROM KRWF TO JUST EAST OF KDSM AT THIS TIME. THIS CAN BE SEEN ON SPC MESOA PAGE DEEP MCONVERGENCE PARAMETER /SFC-2KM AGL/. THIS IS ALSO WHERE AN INCREDIBLY STRONG MOISTURE GRADIENT EXISTS FROM -18C NEAR KDSM TO 20C AT KOMA AT 850 MB. THIS CONVERGENCE OF THE LOW-LEVEL FLOW AND MOISTURE ADVECTION CONTINUES TOWARD ARX WESTERN FORECAST AREA OVERNIGHT ARRIVING LATE. THE MAIN QUESTION IS WILL THAT VERY WARM LAYER OF AIR IN THE 650-850MB LAYER BE ABLE TO SATURATE IN MODERATE MOISTURE CONVERGENCE. IF THE BOTTOM OF THAT LAYER SATURATES...THERE IS STILL SOME NEGATIVE AREA TO OVERCOME FOR TSRA INITIATION. BETTER CHANCE AT CONVECTION MAY BE IF THE LAYER A BIT HIGHER SATURATES AS THE INHIBITION ABOVE THOSE PARCELS WILL BE LESS...AND SO WILL THE CONVECTIVE INTENSITY. CURRENT ACCAS ACTIVITY IS BASED NEAR 550 MB PER KMPX SOUNDING AT 00Z. IF WE COULD PRODUCE SOME SHOWERY/VIRGA ACTIVITY AHEAD OF THE MOISTURE CONVERGENCE IN NRN IOWA...IT WOULD ACT TO COOL THE WARM AIR LAYER SOME DIABATICALLY AND INCREASE THE CONVECTIVE CHANCES. THE 03.00Z NAM WRF HAS BACKED DOWN TO SHRA /VERSUS TSRA/ DEVELOPMENT LATER TONIGHT IN THE MOISTURE CONVERGENCE AND IT REALLY ONLY TOUCHES THE EXTREME WRN FORECAST AREA. LOCAL 03.21Z RUC INITIALIZED WRF MODEL ONLY DEVELOPS LIGHT REFLECTIVITY ECHO ON THIS MOISTURE RETURN...A SIGN IT IS BATTLING THE WARM AIR ALOFT IT SEEMS. BOTTOM LINE...HAVE PULLED THE RAIN CHANCES ALONG AND EAST OF RIVER PRIOR TO 12Z AND TIGHTENED THE GRADIENT ACROSS NERN IA AND SERN MN. KEPT THE 50-60 PERCENT ON WESTERN EDGE PER COLLABORATED FORECAST WITH MPX/DMX. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ BAUMGARDT wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 210 PM CDT SAT AUG 2 2008 .SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT FORECAST CONCERNS REMAIN STORM THREATS NEXT FEW DAYS AS UPPER RIDGE FLATTENS AND LOW LEVEL MOISTURE RETURNS. GORGEOUS EARLY AUGUST DAY CURRENTLY AS UPPER RIDGE BUILDS AND DRY AIRMASS FIRMLY IN PLACE. COMBINATION OF UPSTREAM CONVECTIVE DEBRIS AND ACCAS FIELD WILL WORK INTO THE AREA THIS EVENING. WHILE SURFACE WARM FRONT IS WELL SOUTHWEST OF THE AREA...WIND AND VAD WIND PROFILERS SUGGEST ABOVE FRONT AN INCREASING SOUTHWEST FLOW AND CONVERGENCE. VERY STRONG 850 MB THETA-E ADVECTION ALSO NOTED IN RUC MODEL IN THIS SAME ZONE...FROM WESTERN IOWA INTO EASTERN SOUTH DAKOTA. THIS MOISTURE PUSH NORTHEAST WILL BE MAIN PLAYER AT SOME POINT TONIGHT...WITH CONVECTION EXPECTED TO BLOSSOM JUST WEST OF FORECAST AREA PERHAPS BY LATE EVENING AS CAP BREAKS DOWN. BETTER MOST UNSTABLE CAPE VALUES REMAIN WEST OF AREA THROUGH THE NIGHT SO CONFIDENCE IN SEVERE THUNDERSTORMS LACKING BUT WOULD EXPECT AT LEAST SOME STRONG STORMS AND OUTSIDE RISK OF ISOLATED SEVERE THROUGH THE OVERNIGHT MAINLY WEST OF THE MISSISSIPPI RIVER. THIS ACTIVITY LIKELY TO SPREAD EAST THEN ON SUNDAY BUT DETAILS AFTER THAT BECOME A BIT MORE SKETCHY. SHORT TERM GUIDANCE REMAINS CONSISTENT ON IDEA OF LARGE UPPER LOW/TROUGH MOVING ACROSS CANADA SETTING UP MORE ZONAL FLOW. LOW LEVEL RESPONSE WILL BE PROLONGED WARM AIR ADVECTION AND MODEST MOISTURE TRANSPORT INTO THE AREA. COMBINED WITH NEARBY WARM FRONT...SHOULD SEE RAPID RECOVERY AND DESTABLIZATION ON SUNDAY LEADING TO ANOTHER THREAT FOR THUNDERSTORMS BY SUNDAY NIGHT. AS UPPER TROUGH BECOMES MORE DOMINANT APPROACHING ONTARIO... COLDER BOUNDARY WILL PUSH SOUTH ON MONDAY IT APPEARS. STILL WILL REMAIN QUITE UNSTABLE ALONG AND AHEAD OF THIS SETTING UP PERHAPS BEST CHANCES OF RAIN ON MONDAY BUT TREND INTO TUESDAY NIGHT WILL BE FOR DRIER AND COOLER AIR TO ADVECT IN AS NORTHWEST FLOW TAKES OVER. TEMPERATURES NEXT FEW DAYS COULD BE QUITE WARM BUT PRECIPITATION TIMING AND CLOUD DEBRIS WILL LIKELY KEEP THEM FROM GETTING TOO HIGH AND HENCE HAVE LOWERED FORECAST MAXIMUMS SLIGHTLY. .LONG TERM...WEDNESDAY THROUGH SATURDAY ANOMALOUS UPPER LOW/TROUGH WILL CONTINUE TO SETTLE INTO ONTARIO AND EVENTUALLY NORTHEAST U.S. IN LATER PERIODS. THIS WILL MAKE FOR QUIETER AND COOLER PATTERN INTO NEXT WEEKEND. 02.00Z ECMWF RUN IS MORE PROGRESSIVE WITH MOVING THIS LOW FURTHER SOUTHEAST IN TIME WHILE 02.06Z GFS/DGEX SOLUTIONS ARE A BIT SLOWER. ALTHOUGH PREFER ECMWF SOLUTION...EVEN WITH MODEL BLEND SURFACE BOUNDARY SHOULD SHIFT SOUTH OF THE AREA AND KEEP STRONGER CONVECTION THREATS TO THE SOUTH AND SOUTHWEST. COLD POOL ALOFT ASSOCIATED WITH UPPER LOW COULD GENERATE SOME MAINLY DIURNAL INSTABILITY SHOWERS AS CLOSE AS CENTRAL WISCONSIN BUT OVERALL THREAT LOOKS FAIRLY LOW AT THIS POINT AND MAY NOT INCLUDE SMALL CHANCES. && .AVIATION... SOUTHERLY FLOW AND INCREASING INSTABILITY SHOULD RETURN IN EARNEST MAINLY WEST OF THE MISSISSIPPI RIVER BETWEEN 03.06Z-03.12Z. AS A RESULT...CLUSTER OF THUNDERSTORMS EXPECTED TO DEVELOP IN THIS TIME FRAME OVER PARTS OF SOUTHWEST MN INTO NORTHERN IOWA. THESE SHOULD PROPAGATE SOUTHEASTWARD...POSSIBLY AFFECTING KRST TAF SITE. ANY LINGERING THUNDERSTORMS THROUGH 03.18Z SHOULD REMAIN GENERALLY WEST OF THE MISSISSIPPI RIVER...WHERE HIGHEST INSTABILITY RESIDES. IN ADDITION...MVFR CEILINGS MAY BE A FACTOR ON SUNDAY AT KRST...AS LOW LEVEL RELATIVE HUMIDITY INCREASES WITH STRENGTHENING SOUTHERLY FLOW. CONFIDENCE WAS NOT HIGH ENOUGH TO INCLUDE MVFR AT THIS TIME...DUE TO UNCERTAINTY IN TIMING AND AREAL EXTENT. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT/LONG TERM...SHEA AVIATION..........THOMPSON wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 413 AM CDT FRI AUG 1 2008 FORECAST FOCUS ON TEMPERATURES SHORT TERM...PRECIPITATION CHANCE IN THE LONG TERM PERIOD. LATEST WATER VAPOR IMAGERY INDICATED AN UPPER LEVEL RIDGE SHIFTING EASTWARD ACROSS THE NORTHERN ROCKIES. DOWNSTREAM OF THIS FEATURE...A SHORTWAVE TROUGH/VORTICITY MAXIMUM WAS LOCATED OVER FAR NORTHERN MINNESOTA AND SOUTHWEST ONTARIO CANADA. RUC ANALYSIS INDICATED VORTICITY LOBE EXTENDING SOUTH INTO NORTHWEST WISCONSIN...AND HELPING TO PRODUCE ISOLATED SHOWERS AND THUNDERSTORMS THERE. AT THE SURFACE...HIGH PRESSURE WAS BUILDING INTO THE NORTHERN PLAINS. .SHORT TERM...TODAY THROUGH SUNDAY... WILL MENTION PATCHY FOG IN EARLY MORNING HOURS GIVEN LIGHT WINDS AND MAINLY CLEAR SKIES ACROSS THE AREA...AND CURRENT OBSERVATIONS. NAM/GFS HAVE VORTICITY MAXIMUM DROPPING SOUTHEAST TODAY...BRUSHING THE NORTHEAST COUNTIES. GFS SOUNDINGS SEEM TO HAVE A BETTER HANDLE ON EXPECTED LOWER DEW POINTS THROUGH THE DAY TODAY THAN THE NAM...AND THEREFORE HAVE MUCH LESS CAPE. WILL INCLUDE A SLIGHT CHANCE IN THE EAST FROM MID MORNING ON...GIVEN CLOSE PROXIMITY OF PASSING VORTICITY MAXIMUM. MOST OF THE DAY SHOULD BE DRY...AS HIGH PRESSURE MOVES TOWARD THE AREA. THE HIGH WILL THEN MOVE ACROSS THE AREA TONIGHT AND SATURDAY...BRINGING LESS HUMID CONDITIONS TO THE AREA. MAY SEE PATCHY FOG TONIGHT IN THE RIVER VALLEYS...WITH FEW CLOUDS AND LIGHT WINDS AROUND. TEMPERATURES WILL CONTINUE TO BE WARM AWAY FROM THE LAKESHORE THROUGH SUNDAY. WINDS SHIFTING ONSHORE NEAR THE LAKE WILL KEEP HIGHS THERE COOLER. AS HIGH PASSES TO THE EAST SATURDAY NIGHT...A 40 KNOT PLUS LOW LEVEL JET POINTS TOWARD SOUTHWEST WISCONSIN. THIS FEATURE PERSISTS ON SUNDAY...THOUGH AT A WEAKER MAGNITUDE. GFS MORE BULLISH THAN THE NAM ON EXPECTED INSTABILITY...MAINLY ELEVATED IN NATURE. NAM DOES BRING AN MCS JUST TO THE SOUTHWEST OF THE FORECAST AREA SATURDAY NIGHT...WITH REMNANTS INTO SUNDAY. GFS WAS MUCH LESS OPTIMISTIC ON QPF. WILL CARRY SLIGHT CHANCE TO CHANCE POPS SATURDAY NIGHT AND SUNDAY. .LONG TERM...SUNDAY NIGHT THROUGH THURSDAY... GFS AND ECMWF INDICATED THE STRONG LOW LEVEL JET NOSE TO CONTINUE SUNDAY NIGHT...WITH A LOW PRESSURE SYSTEM PASSING THROUGH THE REGION MONDAY...THEN DROPPING A COLD FRONT THROUGH THE AREA MONDAY NIGHT. STRONG WARM AIR ADVECTION TAKES PLACE ON THE GFS ON MONDAY...WITH 850MB TEMPERATURES OF 26 DEGREES CELSIUS...AND 1000/500MB THICKNESSES RISING INTO THE LOWER 580S DKM. WILL KEEP CHANCY WORDING IN FORECAST FOR SUNDAY NIGHT THROUGH WEDNESDAY...GIVEN THE MODEL UNCERTAINTY FOR EXPECTED CAPE VALUES. HIGHS WELL INTO THE 90S FAHRENHEIT POSSIBLE IF GFS VERIFIES WITH ANY SUNSHINE. && .AVIATION...SOME MORNING FOG...ESPECIALLY AT KMSN...SHOULD LIFT BY 14Z. OTHERWISE...VFR THROUGH THE PERIOD. SLGT CHANCE FOR THUNDERSTORMS THIS AFTERNOON AS H5 S/W DROPS SOUTHEAST THROUGH THE GREAT LAKES. WILL NOT BE REFLECTED IN TAF FOR KMKE OR KENW. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && $$ SHORT/LONG TERM...08/WOOD AVIATION/MARINE...05/DAVIS wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 324 AM CDT FRI AUG 1 2008 .SHORT TERM...TODAY THROUGH SUNDAY NIGHT FORECAST CONCERNS ARE ON TEMPERATURES NEXT SEVERAL DAYS ALONG WITH CORRESPONDING HEAT INDEX VALUES. ALSO POTENTIAL MCS SATURDAY NIGHT AND EARLY SUNDAY ALSO A CONCERN. 07Z SURFACE ANALYSIS SHOWS FRONTAL BOUNDARY EXTENDING FROM EASTERN WISCONSIN SOUTHWEST INTO SOUTHERN IOWA. WHILE PROFILER DATA SHOWING LOW LEVEL NORTHERLY WINDS AS FAR SOUTH AS SLATER IOWA. CONVECTION ASSOCIATED WITH THIS FRONT CONFINED ACROSS EASTERN IOWA AND MOVING AWAY FROM THE AREA. MEANWHILE...FARTHER NORTH WATER VAPOR IMAGERY SHOWING WELL DEFINED SHORTWAVE NEAR LAKE WINNIPEG. UPPER SPEED MAX AHEAD OF THE WAVE AS DEPICTED BY THE 01.06Z RUC RESULTING IN A SMALL CLUSTER OF CONVECTION ACROSS NORTHWEST WISCONSIN. WITH THE LIGHT WINDS AND RECENT RAINS...SURFACE REPORTS SHOWING FOG DEVELOPING ACROSS THE AREA...LOCALLY DENSE IN SOME OF THE RIVER VALLEYS. 01.00Z NCEP DETERMINISTIC MODELS IN GOOD AGREEMENT WITH THE BROAD SCALE FLOW. HOWEVER...RECENT PERFORMANCE ON MCS GENERATION AND MOVEMENT HAS BEEN POOR. THUS CONFIDENCE MEDIUM FOR THE POTENTIAL MCS ACTIVITY LATE SATURDAY NIGHT AND SUNDAY MORNING. IN THE NEAR TERM...SHORTWAVE NEAR LAKE WINNIPEG WILL DROP SOUTHEAST ACROSS THE UPPER PENINSULA OF MICHIGAN TODAY. THIS WILL HELP SHIFT MAIN BOUNDARY SOUTH OF THE AREA. ALTHOUGH FORCING ASSOCIATED WITH THE WAVE WILL REMAIN NORTH OF THE AREA...BOTH THE NAM AND GFS SHOW SOME WEAK INSTABILITY THIS AFTERNOON. CAN NOT RULE OUT AN ISOLATED SHOWER OR THUNDERSTORM...BUT PROBABILITIES TOO LOW TO MENTION AND WILL GO WITH DRY FORECAST. HIGH PRESSURE BUILDS SOUTHEAST FROM THE PLAINS INTO THE UPPER MISSISSIPPI RIVER VALLEY REGION TONIGHT. WITH NEARLY CALM WINDS AND CLEAR SKIES WILL LIKELY SEE SOME FOG FORM...ESPECIALLY IN THE FAVORED VALLEY LOCATIONS. THIS ALREADY ADDRESSED IN THE GRIDS. AS THE HIGH BEGINS TO SHIFT EASTWARD SATURDAY...RETURN FLOW ESTABLISHES ITSELF ACROSS THE PLAINS. QUIET AND HOT WEATHER LOOKS TO BE THE RULE AS A SURFACE LOW DEVELOPS OUT ACROSS THE PLAINS AND THE ASSOCIATED WARM FRONT BEGINNING TO LIFT NORTHWARD. ENOUGH INFLUENCE FROM THE HIGH DURING THE DAY SATURDAY TO KEEP THINGS DRY. HOWEVER BY SATURDAY NIGHT THE LOW LEVEL JET STRENGTHENS ACROSS IOWA WITH 850MB MOISTURE TRANSPORT IMPINGING ON THE WARM FRONT. BOTH THE GFS AND NAM SHOWING CONVECTION DEVELOPING DURING THE EVENING ACROSS WESTERN MINNESOTA/EASTERN DAKOTAS THEN PUSHING EAST/SOUTHEAST TOWARD THE AREA. BETTER CHANCES FOR THE FORECAST AREA LOOKS TO BE AFTER MIDNIGHT. THUS HAVE TRIMMED POPS ACROSS THE AREA FOR THE EVENING HOURS. QUESTION FOR SUNDAY WILL BE LINGERING MORNING CONVECTION AND CLOUD COVER. BETTER RAIN CHANCES LOOK TO BE DURING THE MORNING HOURS WITH DECAYING MCS. MODELS SHOWING WARMING 850MB-700MB TEMPERATURES THROUGH THE DAY AND THUS MAY CAP OFF DURING THE AFTERNOON HOURS. FOR NOW WILL KEEP POP AS A 12 HOUR BLOCK...BUT MAY BE ABLE TO REFINE WITH LATER MODEL RUNS. FRONT CONTINUES TO HANG AROUND THE AREA SUNDAY NIGHT WITH LOW LEVEL JET ONCE AGAIN STRENGTHENING DURING THE OVERNIGHT HOURS. WILL CONTINUE CHANCE POPS IN THE TIME FRAME. TEMPERATURES LOOK TO CONTINUE ABOVE SEASONAL NORMALS CRACKING THE 90 DEGREE MARK FOR BOTH SATURDAY AND SUNDAY IN SOME LOCATIONS. WITH INCREASING MOISTURE WILL HAVE TO WATCH FOR THE POTENTIAL FOR HEAT ADVISORY CRITERIA BEING MET. .LONG TERM...MONDAY THROUGH THURSDAY BOTH THE 01.00Z GFS AND ECMWF SIMILAR IN KEEPING FRONT NEAR THE AREA THROUGH TUESDAY. THUS WILL CONTINUE RAIN CHANCES IN THIS TIME FRAME. MODELS HINTING THAT THIS BOUNDARY MAY PUSH SOUTH OF THE AREA BY WEDNESDAY. IF THIS IS THE CASE MAY SEE SOME DRIER AIR ADVECT INTO THE AREA WITH MAIN CONVECTION BEING PUSHED TO THE SOUTH. CURRENT GRIDS SHOW A DECREASING POP TREND IN THIS TIME FRAME AND THIS LOOKS REASONABLE. THUS PLAN NO CHANGES THROUGH THIS PERIOD. && .AVIATION...TODAY AND TONIGHT AREAS OF FOG WILL BE FOUND WEST OF AN EAU CLAIRE TO WISCONSIN DELLS LINE THIS MORNING. THIS FOG MAY BE LOCALLY DENSE AT TIMES IN THE RIVER VALLEYS. IN ADDITION...IFR CEILINGS WILL BE LIKELY IN RIVER VALLEYS TOO. THIS FOG SHOULD DISSIPATE AROUND 9 AM. AFTER THIS OCCURS...VFR CONDITIONS SHOULD PREVAIL THROUGH THE REST OF THE TODAY AND INTO THIS EVENING. VALLEY FOG MAY DEVELOP ONCE AGAIN TONIGHT AFTER 02.06Z. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT/LONG TERM...RABERDING AVIATION..........BOYNE wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 352 AM EDT SUN AUG 3 2008 .SYNOPSIS... 07Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED THE HEAT RIDGE IN THE CENTRAL PLAINS NOTED BY A 595 DAM HIGH OVER EASTERN KANSAS. RIDGING EXTENDED NORTHEAST OF THIS HIGH ACROSS WESTERN LAKE SUPERIOR AND INTO NORTHERN ONTARIO. AN UPPER TROUGH EXISTS TO THE WEST OF THE RIDGE FROM THE PACIFIC NW INTO CENTRAL CANADA. BETWEEN THE TROUGH AND RIDGE...MAIN SHRTWV OF NOTE IS IN SW MONTANA WHICH IS HELPING WITH CONVECTION IN EASTERN MONTANA AND NW SOUTH DAKOTA. WEATHER IS QUIET OVER UPPER MI THANKS TO HIGH PRESSURE OVER THE AREA...WITH ONLY SOME SCATTERED HIGH CLOUDS MOVING ACROSS. DRY AIRMASS PRESENT AS WELL...WITH PRECIPITABLE WATER OF 0.85 INCHES AT GRB AND 0.74 INCHES AT APX. HIGHER MOISTURE IS FARTHER OFF TO THE SOUTH AND WEST...NOTED BY PRECIPITABLE WATER VALUES OF 1.41 INCHES AT BIS...1.71 INCHES AT OAX AND 1.46 INCHES AT TOP. THESE HIGHER PRECIPITABLE WATERS ARE ALSO NOTED IN THE SURFACE DEWPOINTS WITH READINGS AROUND 70F. && .DISCUSSION... MAIN FORECAST CONCERNS ARE LOCATION OF MCS DEVELOPMENT TONIGHT AND POTENTIAL FOR SEVERE WEATHER ON TUE. TODAY...UPPER RIDGE AXIS OVER WESTERN LAKE SUPERIOR SHIFTS OVER UPPER MI DURING THE AFTERNOON. SUBSIDENCE UNDER THIS UPPER RIDGE...ALONG WITH THE LARGE AMOUNT OF DRY AIR OVER THE CWA THANKS TO THE HIGH PRESSURE AREA REMAINING CLOSE BY...SHOULD KEEP MUCH OF THE CWA DRY. HOWEVER...WITH HEIGHT FALLS COMING INTO WESTERN LAKE SUPERIOR DURING THE LATE AFTERNOON ALONG WITH SOME MOISTURE RETURN...CANNOT COUNT OUT SOME CONVECTION THAT IS EXPECTED TO DEVELOP OVER CENTRAL MN FROM SPREADING ONTO WESTERN LAKE SUPERIOR...OR PERHAPS EVEN INTO IWD. OTHERWISE...WITH ONLY A GRADUAL INCREASE IN CLOUD COVER EXPECTED AND 850MB TEMPS AROUND 14C...TEMPERATURES SHOULD BE ABLE TO CLIMB AT LEAST INTO THE LOW 80S. HIGH PRESSURE NEARBY (OFF TO THE EAST IN LOWER MI) SUGGESTS FORMATION OF SOME LAKE BREEZES...WHICH COULD GET GUSTY OFF LAKE MI WITH ENHANCEMENT BY THE RETURN FLOW. THEREFORE...COOLER TEMPS ARE INDICATED FOR BOTH LAKE MI SHORELINE AND SOME IMMEDIATE LAKE SUPERIOR SHORELINE LOCATIONS. TONIGHT...UPPER FLOW ACROSS THE NORTHERN U.S. IS PROGGED TO BECOME A BIT MORE ZONAL AS THE TROUGH IN THE PACIFIC NW STARTS PUSHING EAST. AS THIS OCCURS...THE SHRTWV CURRENTLY IN SW MONTANA IS PROGGED TO MOVE INTO NORTHERN MN BY 06Z AND INTO NORTHERN LAKE SUPERIOR BY 12Z MON. THIS SHRTWV SHOULD HELP PUSH THE UPPER RIDGE OVER UPPER MI EASTWARD...PLACING THE AREA IN A WARM ADVECTION ZONE IN THE LOW LEVELS. THIS WARM ADVECTION...COMBINED WITH THE SHRTWV MOVING IN...LIKELY MEANS THE DEVELOPMENT OF AN MCS SOMEWHERE IN THE WESTERN GREAT LAKES. LOCATION DEPENDS HIGHLY ON FAR NORTH THE CAP FROM THE HEAT RIDGE IN THE CENTRAL PLAINS MOVES NORTH...AS THE EDGE OF THIS CAP IS LIKELY WHERE THE MCS TRACKS ALONG. THE 00Z UKMET REMAINS CONSISTENT WITH MANY OF ITS PREVIOUS RUNS SHOWING DEVELOPMENT FROM CENTRAL MN INTO NRN WI AND UPPER MI...SINCE IT BRINGS 850MB TEMPS OF 20C OR GREATER TO A LINE FROM HINCKELY MN TO MADISON WI BY 06Z TUE. THE REGIONAL CANADIAN IS PRACTICALLY IDENTICAL TO THE UKMET. OUR LOCAL WRF-ARW RUNS ARE SIMILAR TO THE UKMET...ONLY A LITTLE SOUTH. THE 00Z NAM/ECMWF ARE FARTHER SOUTH...DEVELOPING THE MCS OVER SRN MN AND TRACKING IT EASTWARD INTO CENTRAL WI...WITH UPPER MI GETTING INTO THE NRN FRINGES OF THE PCPN FIELD. THE 00Z GFS IS SIMILAR TO OUR LOCAL WRF-ARW RUN...BUT SLOWER...TAKING AN MCS FROM CENTRAL MN INTO SRN UPPER MI BETWEEN 12-18Z MON. GIVEN THE DIFFERENCES...HAVE ONLY ENOUGH CONFIDENCE AT THIS POINT TO GO NO HIGHER THAN 50 POPS...GREATEST IN THE SOUTHERN U.P.. NEXT SHIFT CAN DETERMINE WHETHER TO RAISE POPS FURTHER ONCE MORE CERTAINTY DEVELOPS ON HOW FAR NORTH THE CAP LIFTS TODAY IN MN. WHEREVER THE MCS OCCURS...THERE WILL BE A POSSIBILITY FOR SEVERE WEATHER...WITH DAMAGING WINDS PROBABLY THE MAIN THREAT SINCE FREEZING LEVELS ARE QUITE HIGH (14500 FT OR HIGHER). SHOULD BE A WARM NIGHT...WITH READINGS IN THE LOW 60S. MONDAY...BASE OF UPPER TROUGH IN THE PACIFIC NW IS PROGGED TO SHIFT INTO SOUTH CENTRAL CANADA AND NORTH DAKOTA. THIS MEANS SOME WEAK RIDGING MAY GET BUILT UP OVER THE CWA THROUGH THE DAY...AND THUS PROVIDE SOME CAPPING AND SUBSIDENCE. THEREFORE...HAVE ADJUSTED THE FORECAST TO GO WITH LOWER POPS IN THE AFTERNOON. HOWEVER...THE MORNING FORECAST IS A BIT MORE TROUBLESOME AS IT HIGHLY DEPENDS ON THE LOCATION OF TONIGHTS MCS. FOLLOWING THE PREVIOUS DISCUSSION... HAVE WENT WITH HIGHER POPS IN THE SOUTHERN U.P. WHICH SHOULD BE CLOSE TO OR POSSIBLY ON THE MCS TRACK (NOTED BY THE 00Z GFS). ANOTHER REASON FOR LOWER POPS DURING THE AFTERNOON IS THAT THE AREA SHOULD HAVE A HARDER TIME HEATING UP DUE TO CLOUD COVER OFF THE MCS...NO MATTER WHERE THE MCS IS. GUIDANCE TEMPS COOLED DOWN...AND OUR LOCAL WRF-ARW RUN EVEN SHOWS HIGHS IN THE LOW 70S. THEREFORE... TWEAKED THE HIGHS DOWNWARD A FEW DEGREES. DID NOT WANT TO GO TOO LOW GIVEN THAT 850MB TEMPS IN THE AFTN ARE 14-16C...WHICH WITH ANY SUN COULD ALLOW SURFACE TEMPS TO RISE QUICKLY. ALTHOUGH TEMPS WERE COOLED...IT STILL LOOKS LIKE A BIT HUMID AS THE HIGHER DEWPOINTS OVER THE DAKOTAS SHIFT INTO UPPER MI. MON NIGHT...SHRTWV TROUGH OVER NORTH DAKOTA IS INDICATED TO MOVE INTO NRN MN AND NW ONTARIO...RESULTING IN HEIGHT FALLS OVER THE CWA THROUGH THE NIGHT. HAVE STILL LEFT IN SOME CHANCE POPS FOR THESE HEIGHT FALLS...BUT AM NOT OVERLY EXCITED ABOUT PCPN CHANCES GIVEN TIME OF DAY. MODELS REFLECT THIS BY SOME NOT GENERATING ANY QPF AND OTHERS ONLY SOME LIGHT QPF. TEMPS AGAIN SHOULD BE ON THE MILD SIDE GIVEN THE HIGHER DEWPOINTS THAT MOVED IN ON MONDAY. TUE...WEATHER IS LOOKING A BIT MORE INTERESTING. SHRTWV TROUGH IN NRN MN AND NW ONTARIO IS NOW PROGGED BY THE MODELS TO DIG DOWN INTO UPPER MI DURING THE AFTERNOON...AIDED BY ANOTHER SHRTWV CURRENTLY ON THE WEST SIDE OF THE TROUGH OVER BRITISH COLUMBIA. THIS DIGGING IS REPRESENTED BY 500MB HEIGHT FALLS OF ANYWHERE FROM 40 TO 80 METERS...AS INDICATED BY THE ECMWF/UKMET/NAM. GIVEN THE TIMING OF THE SHRTWV COMING DOWN DURING THE AFTERNOON...A SURFACE TROUGH MOVING THROUGH...DEWPOINTS STILL BEING HELD UP IN THE LOW TO MID 60S AHEAD OF THE TROUGH...AND SURFACE HEATING THAT WILL OCCUR DURING THE MORNING (HIGHS EXPECTED IN THE MID TO UPPER 70S AWAY FROM THE SHORELINES)...EXPECTING THAT SHOWERS AND THUNDERSTORMS TO DEVELOP DURING THE AFTERNOON. CONFIDENCE IS HIGH ENOUGH AT THIS POINT TO INCLUDE COVERAGE WORDING. IN ADDITION...WITH 0-6KM BULK SHEAR OF 40-45 KT AND MLCAPE VALUES OF 1000-1500 J/KG...SOME SEVERE WEATHER SEEMS POSSIBLE. HAIL MAY NOT BE THAT GREAT OF HAZARD WITH HIGH FREEZING LEVELS AGAIN...HOWEVER HIGH SURFACE TO 10000 FT DELTA THETA-E VALUES (AROUND 25) AS A RESULT OF DRY MID-LEVEL AIR MOVING IN SUGGESTS A DEFINITE ISSUE FOR WIND. SEVERE RISK SHOULD BE CONFINED TO THE CENTRAL U.P. AS THE WESTERN U.P. STARTS DRYING OUT WHEN THE SHRTWV MOVES IN. SPC DAY3 OUTLOOK HAS THE CENTRAL/EASTERN U.P. IN A SEVERE RISK. TUE NIGHT AND WED...DRYING WILL COME INTO THE CWA TUE NIGHT BEHIND TUE AFTNS SHRTWV. THEREFORE GOING DRY FORECAST IS ON TRACK. IN ADDITION...COOLER TEMPS WILL ALSO MOVE IN. WAS TEMPTED TO LEAVE THE FORECAST DRY FOR WED AS WELL...HOWEVER THERE ARE INDICATIONS OF ANOTHER SHRTWV DIVING THROUGH UPPER MI AS THE BEGINNINGS OF AN UPPER TROUGH FORM OVER SE CANADA INTO THE GREAT LAKES. BOTH THE ECMWF AND GFS SHOW THIS SHRTWV...BUT ONLY THE GFS PRODUCES PCPN. THE PCPN AREA IS CONFINED TO THE CENTRAL U.P. DURING THE AFTN DUE TO LAKE BREEZE CONVERGENCE. MODIFIED SOUNDING FROM THE AREA WHERE PCPN IS PRODUCED TO REMOVE THE HIGH SURFACE DEWPOINT BIAS STILL SUGGESTS AROUND 500 J/KG (INSTEAD OF THE 900 J/KG). THEREFORE HAVE WENT AHEAD AND INCLUDED A 20 POP. OTHER PCPN MAY MOVE INTO WESTERN LAKE SUPERIOR DURING THE AFTN OFF THE MN ARROWHEAD ASSOCIATED WITH ANOTHER SHRTWV. GOING TEMP FORECAST FOR WED SEEMED REASONABLE. NO OTHER CHANGES MADE BEYOND WED. STILL LOOKS LIKE UNSEASONABLY COOL WEATHER TO MOVE IN TOWARDS THE END OF THE WEEK AS 850MB TEMPS DROP TO 6-8C. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... AS SFC HIGH PRES DRIFTS E OF THE UPPER GREAT LAKES...DRY LOW-LEVELS WILL LINGER...RESULTING IN VFR CONDITIONS PERSISTING THRU THIS FCST PERIOD AT KCMX/KSAW. NEAR THE END OF THIS FCST PERIOD...APPROACHING DISTURBANCE COULD BRING SHRA/TSRA TO KCMX. HOWEVER...CONFIDENCE IN LOCATION AND TIMING OF CONVECTIVE DEVELOPMENT IS TOO UNCERTAIN RIGHT NOW TO INCLUDE A MENTION OF SHRA/TSRA. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... TRICKY FORECAST FOR THE NEXT SEVERAL DAYS IN REGARDS TO CONVECTION AND WHAT IT WILL DO WITH THE WINDS. GFS SUFFERS CONVECTIVE FEEDBACK ISSUES AND TRIED TO STAY AWAY FROM IT AND WENT CLOSER TO THE NAM FOR WINDS AS NO CONVECTIVE FEEDBACK PROBLEMS WITH IT. SPEEDS SHOULD STILL REMAIN AT OR BELOW 20 KTS WITH WEST TO NORTHWEST WINDS UP TO 20 KT ON TUE IN THE WAKE OF A TROUGH. NAM IS A BIT STRONG ON WINDS THEN AND KNOCKED THEM DOWN A BIT. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...AJ AVIATION...ROLFSON MARINE...GM mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 115 AM EDT SUN AUG 3 2008 UPDATED AVIATION DISCUSSION FOR 06Z TAFS .SYNOPSIS... (ISSUED AT 425 PM EDT) WATER IMAGERY AND RUC SHOWING A CLOSED LOW OVER LAKE ONTARIO WITH A DEEP TROUGH AND AXIS STRETCHING SOUTH INTO THE MID ATLANTIC STATES...A RIDGING OVER MINNESOTA AND WESTERN ONTARIO... AND MORE TROUGHING OVER THE PACIFIC NORTHWEST AND WEST COAST. SURFACE ANALYSIS DEPICTS A RIDGE BLANKETING THE UPPER MISSISSIPPI RIVER VALLEY...UPPER GREAT LAKES AND NORTHERN ONTARIO. LOWS ARE OVER NORTHERN SASKATCHEWAN AND SOUTHWEST SOUTH DAKOTA WITH A COLD FRONT STRETCHED BETWEEN THEM. ALSO A WEAK FRONTAL SYSTEM STRETCHES FROM THE CENTRAL PLAINS ACROSS THE OHIO RIVER VALLEY TO THE MID ATLANTIC STATES. && .SHORT TERM... (TONIGHT AND SUN ISSUED AT 425 PM EDT) THE MID LEVEL RIDGE WILL SHIFT A LITTLE MORE INTO CENTRAL ONTARIO AS THE QUEBEC LOW STARTS TO DIG INTO THE NEW ENGLAND. THE SASKATCHEWAN LOW WILL SHIFT A LITTLE EAST ALSO. A WEAK SHORTWAVE RACING THROUGH THE RIDGE WILL SWEEP ACROSS THE FORECAST AREA LAKE TONIGHT. THE SURFACE RIDGE WILL CONTINUE TO BLANKET THE UPPER GREAT LAKES TONIGHT KEEPING DRY AIR IN PLACE WHICH WILL LIMIT CLOUDS AND AND PRECIPITATION POTENTIAL. SKIES SHOULD REMAIN MOSTLY CLEAR TONIGHT ALONG WITH LIGHT WINDS. THE MID LEVEL RIDGE OVER THE PLAINS WILL CONTINUE TO BUILD SHIFT EAST OVER THE FORECAST AREA ON SUNDAY. ANOTHER SHORTWAVE APPROACHING THE RIDGE WILL SLIDE INTO WESTERN U.P. SUNDAY AFTERNOON. THE RIDGE SURFACE RIDGE WILL ALSO SLIP INTO LOWER MICHIGAN AS THE SURFACE TROUGH MOVES INTO MINNESOTA. DRY AIR WITH THE RIDGE WILL KEEP PRECIPITATION OUT OF THE AREA ON SUNDAY. THE WINDS WILL VEER SOUTH ALLOWING LOW LEVEL MOISTURE TO BEGIN TO WORK INTO THE AREA BY LATE IN THE AFTERNOON...CAUSING AN INCREASE IN CLOUDS. THIS SOUTHERLY FLOW WILL ALSO CONTRIBUTE TO WARM AIR ADVECTION. THUS LOOKING FOR TEMPERATURES PUSHING INTO THE MID 80S. .LONG TERM... (SUNDAY NIGHT THRU SATURDAY) SUN NIGHT...THE WAA PATTERN IS EXPECTED TO BRING SHRA/TSRA TOWARD THE WRN GREAT LAKES. THE NAM AND GFS WERE IN AGREEMENT THAT A SHORTWAVE TROUGH...BAND OF 850 MB THETA-E ADVECTION AND ASSOCIATED 305K-310K ISENTROPIC LIFT WILL SPREAD ACROSS THE CWA. HOWEVER...AS IS OFTEN THE CASE...A MORE SIGNIFICANT MCS WOULD MORE LIKELY DEVELOP IN THE AREA OF GREATER INSTABILITY AND 925-850 MB CONV AND MOVE INTO WI (PER REGIONAL GEM AND NAM)...REDUCING MOISTURE INFLOW AND PCPN CHANCES OVER UPPER MI. SO...CURRENT CHANCE POPS STILL LOOK ON TRACK. 850 MB DEWPOINTS TO NEAR 15C AND MUCAPE AND MUCAPE VALUES AROUND 1000 J/KG AND EFFECTIVE SHEAR OF 30-35 KT COULD SUPPORT A FEW STRONGER ELEVATED STORMS...MAINLY OVER THE WEST HALF...WITH THREAT OF SMALL TO MARGINALLY SEVERE HAIL. MON...AFTER ANY MORNING SHRA/TSRA DIMINISH...A WEAK TROUGH/FRONT IS EXPECTED MOVE THROUGH UPPER MI...MAINTAINING A CHANCE FOR SHRA/TSRA. ALTHOUGH SBCAPE VALUES MAY CLIMB INTO THE 1000-1500 RANGE WITH SFC DEWPOINTS INTO THE MID 60S...ONLY CHANCE POPS WERE INCLUDED SINCE NAM/GFS FCST SOUNDINGS SUGGEST CAPPING MAY BE DIFFICULT TO OVERCOME. MON NIGHT INTO TUE...THE TRAILING MID LEVEL SHORTWAVE MOVES THROUGH THE AREA WITH ENOUGH LOW LEVEL MOISTURE IN PLACE TO KEEP SHRA/TSRA CHANCES GOING. WED-SAT...MODELS REMAINED IN FAIRLY GOOD AGREEMENT WITH THE PATTERN EVOLUTION TOWARD A TROUGH OVER SE CANADA. THE RESULTING NW FLOW THROUGH THE WRN GREAT LAKES...500 MB TEMPS TO AROUND -18C...AND A SERIES OF DIFFICULT TO TIME SHORTWAVES THROUGH THE AREA...SUPPORT SHRA/TSRA CHANCES...ESPECIALLY DURING PEAK HEATING. HOWEVER...GIVEN THE RELATIVELY DRY AIRMASS OVER THE AREA...ONLY LOWER END POPS WERE INCLUDED. THE OP GFS...ESPECIALLY THE 12Z RUN...WAS THE MOST AGGRESSIVE WITH THE SHORTWAVE TROUGH MOVING THROUGH THE LAKES THU INTO FRI. THE MORE CONSISTENT ECMWF WAS PREFERRED WHICH STILL CARVES OUT AN UNSEASONABLY DEEP TROUGH. TEMPS WILL REMAIN A BIT BLOW NORMAL AND MAY BE LOWERED FURTHER IF CONFIDENCE BECOMES HIGHER IN A PERIOD OF ENHANCED LOW/MID MOISTURE AND MAINLY CLOUDY SKIES. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... AS SFC HIGH PRES DRIFTS E OF THE UPPER GREAT LAKES...DRY LOW-LEVELS WILL LINGER...RESULTING IN VFR CONDITIONS PERSISTING THRU THIS FCST PERIOD AT KCMX/KSAW. NEAR THE END OF THIS FCST PERIOD...APPROACHING DISTURBANCE COULD BRING SHRA/TSRA TO KCMX. HOWEVER...CONFIDENCE IN LOCATION AND TIMING OF CONVECTIVE DEVELOPMENT IS TOO UNCERTAIN RIGHT NOW TO INCLUDE A MENTION OF SHRA/TSRA. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRESSURE OVER MN WILL MOVE OVER THE WESTERN GREAT LAKES TONIGHT AND THEN DRIFT TO THE EAST ON SUNDAY...KEEPING WINDS UNDER 20 KTS ACROSS LAKE SUPERIOR. SOUTHEASTERLY WINDS WILL INCREASE SUN NIGHT AS A LOW PRESSURE TROUGH APPROACHES FROM MN...BUT SPEEDS SHOULD STILL REMAIN AT OR BELOW 20 KTS. LIGHT WINDS ARE EXPECTED TO CONTINUE MON INTO MON NIGHT WITH THE TROUGH PASSAGE. WEST TO NORTHWEST WINDS MAY CREEP UP TO 20 KT ON TUE IN THE WAKE OF THE TROUGH. ANOTHER TROUGH IS EXPECTED TO DROP NORTH TO SOUTH ACROSS LAKE SUPERIOR ON WED. WEST WINDS OF UP TO 20 KT MAY OCCUR OVER NORTH CENTRAL LAKE SUPERIOR... WITH LIGHT WINDS ELSEWHERE. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM...DLG LONG TERM...JLB AVIATION...ROLFSON MARINE...DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 337 AM CDT SUN AUG 3 2008 .DISCUSSION...MAIN FOCUS OVER THE NEXT FEW DAYS WILL BE RESOLVING INDIVIDUAL PRECIPITATION EVENTS. QUIET ACROSS THE CWA THIS MORNING WITH THE RUC INDICATING A WEAK SHORTWAVE MOVING THROUGH THE CWA. THERE WAS A FAIR AMOUNT OF AC/CI STREAMING THROUGH...ESPECIALLY ACROSS THE NORTHERN HALF OF THE CWA. TEMPS WERE WARMER THAN THE PREVIOUS NIGHT WITH MOST LOCATIONS IN THE 50S AND 60S. SEVERAL MCS/S HAD DEVELOPED IN MONTANA AND THE NORTHERN PLAINS EARLY THIS MORNING...HEADING EAST. SOME FAIRLY IMPRESSIVE STORMS OUT THERE...WITH STRONG WINDS. THE 4KM WRF-NMM SIMULATED REFLECTIVITY PRODUCT ACTUALLY DID A PRETTY GOOD JOB PINPOINTING THE DEVELOPMENT OF THIS MCS...ALTHOUGH IT DID NOT HANDLE CONVECTION FURTHER SOUTH IN NEBRASKA. THE H5 RIDGE BUILDING INTO THE UPPER MIDWEST/WESTERN GREAT LAKES WILL GRADUALLY BREAK DOWN AND FLATTEN DUE TO SHORT WAVE ENERGY MOVING IN FROM THE WEST TODAY AND TONIGHT. THE MODELS ARE HAVING A HARD TIME LATCHING ONTO SPECIFIC SHORTWAVE ENERGY...AND THE EVOLUTION OF CONVECTION AND MCS ACTIVITY WILL BE TRICKY TO PINPOINT THROUGH EARLY IN THE WORK WEEK. WILL HAVE TO GO MAINLY WITH TRENDS AND ASSESSMENT OF MASS FIELDS IN DETERMINING POPS AND QPF. HAVE CLOSELY FOLLOWED HPC QPF WITH SOME EXCEPTIONS. FOR TODAY...WILL HIT THE SW 1/3 OF THE CWA HARDEST THIS MORNING. THE 4KM WRF-NMM SIMULATED REFLECTIVITY INDICATES THAT THE MCS ACTIVITY IN THE DAKOTAS WILL GRADUALLY MIGRATE EASTWARD INTO THE CWA...FIRST REACHING THE WESTERN PORTION OF THE CWA...AND THEN SPREADING ACROSS THE REMAINDER OF THE CWA. WE COULD SEE SOME WEAKENING/DIMINISHING OF THE ACTIVITY AS IT MOVES INTO THE WESTERN GREAT LAKES...WITH SOME REDEVELOPMENT PERHAPS TAKING PLACE AS IT DOES. THE BIG QUESTION IS THE IMPACT CONVECTIVE DEBRIS WILL HAVE ON SURFACE HEATING TODAY. THINK THE BEST CHANCE FOR SOME SURFACE HEATING AND DESTABILIZATION WILL BE IN THE SOUTHERN AND WESTERN PORTIONS OF THE CWA DURING THE AFTERNOON/EVENING. SPC HAS MUCH OF THE SOUTHERN HALF OF THE CWA IN A SLIGHT RISK AND THINK THIS LOOKS REASONABLE IF SOME HEATING CAN OCCUR. WILL GO WITH 30/40 POPS TODAY BUT WILL HAVE TO WATCH CONVECTION IN THE DAKOTAS...IN THE EVENT IT DOES NOT DIMINISH AS PROGGED. GFS ENSEMBLE MEMBERS ARE ACTUALLY IN DECENT AGREEMENT ON BRINGING PRECIPITATION NEARLY CWA- WIDE THIS AFTERNOON. HIGH TEMPS TODAY WILL BE TRICKY DUE TO POTENTIAL FOR CLOUD COVER...BUT WILL GO FAIRLY CLOSE TO MOS. FOR TONIGHT...THINK THERE IS DECENT POTENTIAL FOR MCS DEVELOPMENT AS THE SURFACE LOW IN THE DAKOTAS MOVES INTO SOUTHERN MINNESOTA OVERNIGHT. THE DEVELOPMENT OF A STRONG LLJ WITH IMPRESSIVE LOW LEVEL MOISTURE AND PRECIPITABLE WATER VALUES OVERRIDING THE FRONT WILL COMBINE WITH SHORTWAVE ENERGY TO GENERATE SOME MCS ACTIVITY. WILL INCREASE POPS INTO THE LIKELY CATEGORY FOR THE SOUTHERN 1/3 OF THE CWA TONIGHT. GFS ENSEMBLE MEMBERS ARE FAIRLY SPREAD APART BUT BASED ON THE MASS FIELDS AND THE POSITION OF THE SURFACE LOW/LLJ...WILL INCREASE POPS ANYWAY. COULD STILL BE A FEW SEVERE...ESPECIALLY IN THE SOUTHERN HALF/THIRD OF THE CWA. MONDAY AND MONDAY NIGHT SHOULD CONTINUE TO BE FAIRLY UNSETTLED. WILL CONTINUE WITH LOW POPS AT THIS POINT...BUT WILL HAVE TO WATCH THE SITUATION CLOSELY IN THE EVENT THERE ARE SOME MCS/S. BEST CHANCE WOULD LIKELY BE IN THE SOUTHERN THIRD OF THE CWA. .LONG TERM...TUESDAY THRU SATURDAY... AS WAS MENTIONED AT THIS TIME YDAY..THE LATEST MODEL SOLUTIONS SEEM TO BE TRENDING SLIGHTLY SLOWER WITH THE EASTWARD PROGRESSION OF THE FRONT MON-TUE WITH SUCCESSIVE RUNS..BUT FOR THIS EXTENDED PERIOD IT APPEARS THAT THE INSTABILITY AXIS WILL BE SHUNTED MOSTLY SE OF THE DLH CWA BY TUESDAY. WE HAVE RETAINED SOME LOW POPS DURING THE DAY TUESDAY FOR NOW..BUT WE HAVE KEPT A DRY FORECAST IN PLACE TUE NITE/WED AS LOW LEVEL RIDGING IS PROGGED TO BUILD SWD INTO THE WRN LAKES REGION. FOR THE WED NITE-SAT TIME FRAME...WHILE DIFFERING ON THE DAY TO DAY DETAILS..MOST MEDIUM RANGE GUIDANCE IS STILL CONSISTENT WITH PREVIOUS RUNS IN THE GRADUAL EVOLUTION OF AN ERN CONUS TROF AND RESULTANT LOW LEVEL RIDGING BUILDING OVER ONTARIO TO THE NORTH OF LAKE SUPERIOR LATE THIS WEEK AND INTO THE WEEKEND. SUCH A PATTERN WOULD MOST LIKELY RESULT IN ANY SIGNIFICANT INSTABILITY BEING DISPLACED WELL TO THE SOUTHWEST OF THE DLH CWA..WITH COOL AND RELATIVELY DRY N/NE LOW LEVEL TRAJECTORIES. HENCE..WE HAVE REMOVED MENTION OF PRECIP FRI/SAT AND COOLED TEMPS SLIGHTLY WITH THIS FORECAST ISSUANCE..ESPECIALLY IN CLOSER PROXIMITY TO LAKE SUPERIOR. && .AVIATION...SIMILAR AVIATION CONCERNS THIS PERIOD TO THE PAST 24 HOURS OR SO. MID/HIGH LEVEL CLOUDS RESULTING FROM CONVECTIVE DEBRIS TO OUR WEST AND NORTHWEST. HOWEVER..CLOUDS ARE THIN ENUF TO ALLOW FOR SIGNIFICANT RADIATIONAL COOLING AGAIN THIS MORNING..AND SOME FOG HAS FORMED IN FAVORED LOW LYING TERRAIN AREAS INCLUDING HAYWARD AND HIBBING..WHICH WILL LIKELY PERSIST UNTIL 13-14Z. ALSO..LOW LEVEL JET IS STRONGER THIS MORNING AND HAVE INCLUDED A MENTION OF LOW LEVEL WIND SHEAR FOR WIND SPEED/DIRECTION CHANGE OF GREATER THAN 20 KTS/20 DEGREES WITHIN 2KFT OF SURFACE. CHANCE FOR TSTORMS WILL INCREASE BETWEEN 15-18Z IN KBRD AND 17-19Z IN KHIB/KDLH/KHYR. && POINT TEMPS/POPS... DLH 72 59 79 58 / 40 50 30 30 INL 79 58 80 56 / 30 40 20 30 BRD 83 61 83 59 / 40 60 20 30 HYR 80 61 85 59 / 40 60 30 30 ASX 79 60 79 59 / 30 50 30 30 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. $$ DAP/MILLER mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1147 PM CDT SAT AUG 2 2008 .DISCUSSION... /ISSUED AT 309 PM CDT SAT AUG 2 2008/ THE FORECAST CHALLENGES ARE AREAL COVERAGE AND TIMING OF CONVECTION AND SEVERE WEATHER POTENTIAL LATE TONIGHT THROUGH MONDAY. EARLY MORNING CLEAR SKIES AND DRY AIR ALLOWED FOR A LOW STARTING POINT TO TODAYS TEMPS...AND WITH INCOMING CIRRUS THE MERCURY HAS BEEN SOMEWHAT SLOW TO RISE THIS AFTN. BUT THE CLOUDS AND INCREASING SOUTHERLY FLOW WILL HELP TEMPS NOT TO DROP MUCH TONIGHT. LOWS IN THE UPPER 60S TO LOWER 70S SHOULD BE COMMON IN THE MN FORECAST AREA...10 TO 15 DEGREES WARMER THAN LAST NIGHT. 12Z RAOBS FROM THIS MORNING REVEALED A TIGHT 850-600MB BAROCLINIC ZONE FROM ERN SD INTO IA. THIS HAS PROPAGATED GRADUALLY NEWRD INTO SW MN AND WILL BE THE POTENTIAL BREEDING GROUND FOR SOME STRONG CONVECTION LATE TONIGHT AS LOW LEVEL JET /LLJ/ INCREASES TO 45 TO 50 KTS. SOME ACCAS WAS APPARENT THIS MORNING ON VISIBLE IN NRN IA TOO...INDICATIVE OF ELEVATED INSTABILITY. ISOLD CONVECTION HAS CONTINUED SLOWLY EWRD TODAY AHEAD OF A WEAKENING SHORTWAVE IN SD. THIS HAS BEEN UNDER VERY WARM 700MB TEMPS AS ANALYZED BY THE RUC AT 15C TO 17C. SO THERE IS A SMALL CHANCE OF SOME ISOLD SHOWERS PRIOR TO MIDNIGHT AS LLJ STRENGTHENS. MUCH BETTER POTENTIAL OVERNIGHT WITH STRONG DIFFERENTIAL THETA-E ADVECTION AND ASSOCIATED INCREASES IN INSTABILITY ACROSS SRN MN/NRN IA. STEEP MID-LEVEL LAPSE RATES AT 8-9 C/KM IN THE 700-400MB LAYER ARE PROJECTED BY THE GUIDANCE...WITH DEEP EFFECTIVE SHEAR IN THAT VERTICAL CORRIDOR. THERE IS ALSO FRONTOGENETIC FORCING AND NEGATIVE EPV FURTHER AIDING IN UPWARD MOTION. ELEVATED SUPERCELLS SEEM LIKE A POTENTIAL MODE. 09Z SREF SUPERCELL MODE PROBABILITY IS GREATER THAN 70 PERCENT IN SRN MN OVERNIGHT. FREEZING LEVEL HEIGHTS APPEAR TO BE VERY HIGH /15.5-16.0 KFT/ POSSIBLY NEGATING SVR HAIL. THIS CONVECTION IS EXPECTED TO BUILD/EVOLVE BOTH EWRD AND SWRD THRU THE REMAINDER OF SUN MORNING WITH THE ELEVATED INSTABILITY ON THE PERIPHERY OF THE CAP. SO HAVE INCREASED POPS OVERNIGHT AND SUN MORNING FOR SRN MN AND ERN MN/WRN WI RESPECTIVELY. MCS DEVELOPMENT TO OUR WEST IN ND AND POTENTIALLY SD IS NOT EXPECTED TO IMPACT THE AREA WITH PRECIP...BUT MAY LEAD TO MORE CLOUDS FOR SUN AFTN. DURING THE AFTN ON SUN...850-300MB THICKNESS RIDGE AND ASSOCIATED MID-LEVEL THERMAL RIDGE WILL BUILD INTO THE AREA. AT THE SFC...A SUB 1005MB LOW IS PROJECTED TO BE NEAR NE NEBRASKA LATE IN THE AFTN ON MODEL CONSENSUS WITH A CONNECTED 70F PLUS TD FETCH TO THE GULF. AN ASSOCIATED SFC TROUGH/SECONDARY WARM FRONT IS PROJECTED ON MOST GUIDANCE TO BE NEAR THE MN/IA BORDER. WITH SOME LOW AND MID-LEVEL CLEARING IN THE WAKE OF THE MORNING CONVECTION EXPECTED...ESPECIALLY IN SRN MN...LOW LEVEL INSTABILITY IS EXPECTED TO RAPIDLY INCREASE. HOWEVER...AFOREMENTIONED CAP LEADS TO HIGH MLCIN VALUES ON BOTH THE NAM AND GFS THROUGH 21Z AND EVEN HINTED AT UNTIL 00Z GIVEN CONVECTIVE TEMPS IN THE MID 90S LIKELY NOT BEING REACHED. HOWEVER...IN THE EVE...MID-LEVEL HEIGHTS FALLS ARE EXPECTED TO MOVE INTO THE AREA AHEAD OF A VORT MAXIMA AND CONVECTION IS THEN MUCH MORE LIKELY. WITH INCREASING LLJ SUPPORT...NAMELY IN SRN AND ERN MN AND WRN WI...SOME OF THE CONVECTION MAY VERY WELL BE STRONG TO SEVERE. MON WILL POSE ONE MORE DAY WITH CONVECTIVE POTENTIAL...AS SFC COLD FRONT OOZES SOUTHEAST THROUGH THE FORECAST AREA. OBVIOUSLY A LOT BETWEEN THEN AND NOW...BUT THE MAIN FORECAST TREND HAS BEEN TO SPEED THIS PROGRESSION UP. THIS LIKELY HAS BEEN THE CASE WITH GUIDANCE DUE TO MULTIPLE ROUNDS OF THUNDERSTORMS ON THE NORTHERN SIDE OF THE BOUNDARY. THIS SEEMS LEGIT...SO HAVE TRENDED DOWN POPS IN NRN AND WRN PORTIONS OF THE FORECAST AREA ON MON. TIMING OF IMPULSES IS NEAR IMPOSSIBLE FOR MON...BUT DOES APPEAR THERE ARE DECENT AFTN AND EVE CONVECTIVE CHANCES FOR SRN AND SE MN. FRONT LOOKS TO CLEAR THE FORECAST AREA EITHER LATE MON NIGHT OR EARLY TUES. BEYOND...NORTHWEST FLOW WILL GRADUALLY SET UP THROUGH THE END OF THE WEEK AS ERN NA LONG WAVE TROUGH REDEVELOPS. 850MB TEMPS GRADUALLY WORK DOWNWARDS AND LOW LEVEL DRIER AIR FILTERS IN. SHOULD MAKE FOR A PLEASANT END OF THE WEEK. SOME SIGNS OF VORT SPOKES DURING THU-SAT ON WRN PERIPHERY OF TROUGH...BUT AT THIS POINT THE ECMWF AND GFS WOULD FAVOR THE GREAT LAKES FOR AFTN/EVE SHRA CHANCES. && .AVIATION.../06Z TAF ISSUANCE/ SOMEWHAT COMPLICATED FORECAST. VERY STRONG WARM ADVECTION FROM EASTERN NEB INTO NW IA AND SW MN WILL CAUSE CONVECTION TO DEVELOP OVER PARTS OF SOUTH CENTRAL MN OVERNIGHT. MOST AFFECTED BY THIS DEVELOPMENT WILL BE KRWF...BUT POSSIBLY MSP. AT THIS TIME WILL JUST MENTION VCTS FOR KRWF AND VCSH FOR KMSP. VERY WARM MID LEVEL TEMPS MAY LIMIT COVERAGE OF STORMS...BUT A SUB TROPICAL MOISTURE PLUME INTO NEB AND WESTERN IA COULD OFFSET THIS LIMITATION. HAIL IS POSSIBLE IN THE STRONGER STORMS BUT HIGH FREEZING LEVELS COULD LIMIT SIZE TO JUST INTO CRITERIA. LOWER CEILINGS AND VSBYS FROM STORMS WILL NOT LIKELY AFFECT TAF SITES...BUT PATCHY MVFR CEILINGS OVER WESTERN IA COULD AFFECT SW MN OVERNIGHT. FORCING FOR THE STORMS WILL LAST INTO EARLY MORNING HOURS...THEN WARM MID LEVEL TEMPS WILL LIMIT CONVECTION THROUGH MOST OF THE DAY OVER SOUTHERN MN. ANOTHER WAVE CROSSING MT TONIGHT WILL BE AN ADDITIONAL TRIGGER FOR STORMS OVER CENTRAL MN IN THE LATE AFTERNOON ON SUNDAY NORTH OF THE TROUGH AND BOUNDARY OVER SOUTHERN MN. VERY UNSTABLE AIR AND CONVERGENCE WILL ALLOW THE CAP TO WEAKEN OVER SOUTHERN MN IN THE LATER PART OF THE FORECAST PERIOD. EXPECT MOST TAF SITES TO BE AFFECTED BY CONVECTION LATE SUNDAY AFTERNOON AND NIGHT...BUT ESPECIALLY OVER EASTERN SITES. GENERALLY VFR UNTIL STORMS DEVELOP BUT AREA OF MVFR CEILINGS MAY LINGER SUNDAY MORNING OVER SW MN. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ MTF/JPR mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 326 AM CDT SUN AUG 3 2008 .SHORT TERM...TODAY THROUGH TUESDAY NIGHT FORECAST CONCERNS REMAIN ON PRECIPITATION CHANCES AND SEVERE WEATHER THREAT OVER THE NEXT SEVERAL DAYS IN A RATHER COMPLICATED FORECAST SCENARIO. 07Z SURFACE ANALYSIS SHOWS A WARM FRONT EXTENDING FROM NORTHEAST NEBRASKA...SOUTHEASTWARD INTO MISSOURI. RATHER IMPRESSIVE MOISTURE GRADIENT SEEN ACROSS IOWA WITH MIDDLE TO UPPER 70S DEW POINTS ACROSS THE FAR WEST AND NEAR 60 ACROSS THE EAST. 00Z UPPER AIR ANALYSIS AT 850MB SHOWS A +20 CELSIUS DEW POINT AT KOMA...AND -12 CELSIUS AT KDVN. LATEST PROFILER DATA SHOWS LOW LEVEL JET STRENGTHENING ACROSS SOUTHERN NEBRASKA FEEDING MOISTURE OVER THE BOUNDARY. ELEVATED CONVECTION HAS DEVELOPED ON EDGE OF CAP IN CONVERGENCE AREA NORTH OF THE BOUNDARY OVER CENTRAL AND EASTERN IOWA...WHERE SPS MUCAPES OF 1000 TO 2000 J/KG RESIDE. 03.00Z NCEP DETERMINISTIC MODEL SOLUTIONS ALL CONSISTENT WITH MID LEVEL TROUGH OVER CENTRAL CANADA TRANSLATING EASTWARD AND FLATTENING THE RIDGE ACROSS THE NORTHERN CONUS THROUGH MONDAY...THEN GRADUALLY TRANSITIONING TO A MORE NORTHWESTERLY FLOW BY TUESDAY/TUESDAY NIGHT. BOTH THE 03.00Z GFS AND NAM ALONG WITH THE VARIOUS MESOSCALE MODELS INDICATE WARM FRONT TO LIFT NORTHWARD TODAY INTO THE FORECAST AREA BY THIS AFTERNOON. QUESTION WILL BE HOW FAR NORTH IT GETS. CURRENT MODEL SOLUTIONS HAVE IT INTO SOUTHERN MINNESOTA TO SOUTHERN WISCONSIN LATER IN TH DAY. WARM SECTOR LOOKS TO BECOME CAPPED AS +20 CELSIUS 850MB-700MB AIR ADVECTS IN. LOW LEVEL JET WANES DURING THE MORNING HOURS WITH ONLY SCATTERED CONVECTION AT BEST OVER THE AREA. WILL CONTINUE WITH THE LOWER END CHANCE POPS THOUGH MUCH OF THE DAY...SLIGHTLY HIGHER DURING THE MORNING HOURS AS ELEVATE CAPES EXIST ACROSS THE WESTERN ZONES. FRONTAL BOUNDARY TONIGHT WILL BE DRAPED ACROSS THE FORECAST AREA... GENERALLY FROM SOUTHEAST MINNESOTA INTO SOUTHERN WISCONSIN. LOW LEVEL JET/MOISTURE TRANSPORT INCREASES ONCE AGAIN. BEST CONVERGENCE ALONG AND TO THE NORTH OF THE BOUNDARY ON NOSE OF MOISTURE TRANSPORT. HAVE PLACED HIGHEST POPS IN THE LIKELY CATEGORY ACROSS ABOUT THE NORTH HALF OF THE FORECAST AREA WITH JUST CHANCE POPS TO THE SOUTH OF THE BOUNDARY IN NORTHEAST IOWA AND SOUTHWEST WISCONSIN. FRONT REMAINS STALLED OVER THE AREA MONDAY AND MONDAY NIGHT WITH MOISTURE TRANSPORT CONTINUING. EXPECT SUNDAY NIGHT CONVECTION TO CONTINUE INTO MONDAY MORNING BEFORE LOW LEVEL JET WANES. REDEVELOPMENT EXPECTED LATE MONDAY AFTERNOON OR EVENING ONCE AGAIN. QUESTION WILL BE POSITION OF FRONT. FOR NOW WILL CONTINUE THE CHANCE POPS IN THIS TIME FRAME. AS TROUGH OVER CANADA BUILDS SOUTHWARD ON TUESDAY...SURFACE HIGH PRESSURE WILL BEGIN TO BUILD INTO THE REGION. THIS WILL PUSH FRONT TO THE SOUTH. WILL CONTINUE POPS ON TUESDAY...BUT REMOVE THEN FOR TUESDAY NIGHT AS DRIER AIR ADVECTS INTO THE REGION. TEMPERATURES RATHER TRICKY AS WARM AIRMASS ADVECTS INTO THE REGION BUT WILL BE OFFSET BY CLOUDS AND PRECIPITATION. WARMEST DAY LOOKS TO BE MONDAY AND WILL BE DEPENDENT ON FRONTAL POSITION...BUT A FEW LOCATIONS ACROSS THE SOUTH WILL LIKELY HIT THE 90 DEGREE MARK. GUIDANCE NUMBERS LOOKS REASONABLE AND ONLY MADE MINOR ADJUSTMENTS TO THEM. .LONG TERM...WEDNESDAY THROUGH SATURDAY BOTH THE 03.00Z GFS AND ECMWF SHOWS MID LEVEL TROUGHING SETTLING OVER THE GREAT LAKES REGION DURING THE PERIOD. NORTHWEST FLOW THEN DOMINATES THE FORECAST AREA THROUGH THE PERIOD. COOLER WEATHER IS EXPECTED IN THIS TIME FRAME WITH COLD POOL SHOWERS POSSIBLE ACROSS THE NORTHEAST THURSDAY AFTERNOON. PREVIOUS SET OF GRIDS LOOK IN GOOD SHAPE AND MADE NO CHANGES TO THIS TIME FRAME. && .AVIATION...TODAY AND TONIGHT AT 3 AM...KARX DOPPLER RADAR IS SHOWING A THUNDERSTORM COMPLEX EXTENDING FROM WATERLOO IOWA SOUTHEAST TO BURLINGTON IOWA. ADDITIONAL SHOWERS WERE LOCATED FROM WATERLOO IOWA NORTHEAST TO MARSHALL MINNESOTA. THIS PRECIPITATION WAS DEVELOPING ALONG AN ELEVATED WARM FRONT. SPC RUC IS SHOWING THAT THE MOST UNSTABLE CAPES HAVE CLIMBED BETWEEN 1000 AND 2000 J/KG SINCE MIDNIGHT ACROSS EASTERN IOWA AND NORTH CENTRAL MINNESOTA. FURTHER WEST THE MOST UNSTABLE CAPES ARE IN THE EXCESS OF 4000 J/KG ACROSS WESTERN AND SOUTHERN IOWA AND SOUTHWEST MINNESOTA. THE 850 MB MOISTURE TRANSPORT HAS BEEN INCREASING ALONG THE ELEVATED WARM FRONT ACROSS NORTH CENTRAL IOWA AND SOUTHWEST AND SOUTH CENTRAL MINNESOTA. AS A RESULT...I WOULD EXPECT TO SEE FURTHER DEVELOPMENT SHOWERS AND EVENTUALLY THUNDERSTORMS ACROSS SOUTHERN MINNESOTA AND NORTHEAST IOWA EARLY THIS MORNING. WITH THE 0-6KM EFFECTIVE SHEAR IN THE 40 TO 45 KNOT RANGE...THE WILL BE THE POTENTIAL OF ELEVATED SUPER CELLS. HAIL LOOKS TO BE THE PRIMARY THREAT. HOWEVER WITH THE DOWNDRAFT CAPES CLIMBING ABOVE 1000 J/KG IN OUR FAR WEST...THERE WILL ALSO BE THE POTENTIAL OF DAMAGING WINDS. THE MODELS CONTINUE TO STRUGGLE WITH HOW FAR NORTH THIS WARM FRONT WILL GET TODAY AND TONIGHT. THEY ARE IN GENERAL AGREEMENT THAT IT SHOULD BE SOMEWHERE ACROSS SOUTHERN MINNESOTA AND THE SOUTHERN HALF WISCONSIN. SOUTH OF THIS FRONT...THERE WILL LIKELY BE LITTLE...IF ANY...PRECIPITATION DUE TO STRONG CAPPING. MEANWHILE PRECIPITATION WILL LIKELY PERSIST NORTH OF THE WARM FRONT. A FEW OF THESE THUNDERSTORMS MAY BE SEVERE FROM TIME TO TIME. THE MAIN PROBLEM IS TRYING TO TIME THIS PRECIPITATION...AND I HAVE LITTLE CONFIDENCE IN ANY PARTICULAR TIME PERIOD. INSTEAD OF BLANKETING MUCH OF THE TIME PERIOD WITH THUNDERSTORMS...I WILL LIMITED MY CHANCES TO THE EARLIER PORTIONS OF TAF PERIOD AND GO WITH CB IN THE LATTER PARTS. HOPEFULLY BY DOING THIS WE WILL BE ABLE TO LIMIT THE COVERAGE. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT/LONG TERM...RABERDING AVIATION..........BOYNE wi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1105 AM EDT SUN AUG 3 2008 .SYNOPSIS... WATER VAPOR IMAGERY AND RUC SHOWING A CLOSED LOW OVER NEW ENGLAND...A RIDGE STRETCHING FROM THE CENTRAL PLAINS ACROSS WESTERN U.P. INTO NORTHEAST EAST ONTARIO...AND ANOTHER LOW OVER NORTHWEST MANITOBA WITH A TROUGH EXTENDING SOUTHWEST INTO THE PACIFIC NORTHWEST. WEAK SHORTWAVES TRAVERSING THE RIDGE ARE OVER THE DAKOTAS GENERATING NUMEROUS SHOWERS AND THUNDERSTORMS. AT THE SURFACE...A RIDGE OF HIGH PRESSURE BLANKETS THE GREAT LAKES. A SURFACE LOW IS OVER SOUTH DAKOTA WITH A WARM FRONT LEADING IT AND REACHING SOUTHEAST INTO NORTHERN ALABAMA AND ACROSS TO THE SOUTHERN ATLANTIC COAST. A SURFACE LOW IS OVER NORTHWEST MANITOBA WITH A WEAK COLD FRONT SWEEPING SOUTH THROUGH MANITOBA. && .SHORT TERM... VERY LITTLE CHANGE IN POSITION OF THE MAIN FEATURES LISTED ABOVE ARE EXPECTED. SUBSIDENCE UNDER THIS RIDGE...ALONG WITH THE LARGE AMOUNT OF DRY AIR OVER THE CWA THANKS TO THE HIGH PRESSURE AREA REMAINING CLOSE BY...SHOULD KEEP MUCH OF THE CWA DRY THIS AFTERNOON. HOWEVER...WITH HEIGHT FALLS ISENTROPIC ASCENT AHEAD OF THE FRONT COMING INTO WESTERN LAKE SUPERIOR DURING THE LATE AFTERNOON ALONG WITH SOME MOISTURE RETURN...CANNOT COUNT OUT SOME CONVECTION DEVELOPING OVER CENTRAL MN FROM SPREADING ONTO WESTERN LAKE SUPERIOR...OR PERHAPS EVEN INTO IWD. OTHERWISE...FORECAST SOUNDINGS SHOW WITH ONLY A GRADUAL INCREASE IN CLOUD COVER AND 850MB TEMPS AROUND 14C...TEMPERATURES SHOULD BE ABLE TO CLIMB AT LEAST INTO THE MID 80S. SURFACE HEATING AND LIGHT SOUTHERLY WINDS MAY ALLOW THE FORMATION OF SOME LAKE BREEZES...WHICH COULD GET GUSTY OFF LAKE MI WITH ENHANCEMENT BY THE RETURN FLOW. THEREFORE...COOLER TEMPS ARE INDICATED FOR BOTH LAKE MI SHORELINE AND SOME IMMEDIATE LAKE SUPERIOR SHORELINE LOCATIONS. THE TEMPERATURES ARE RUNNING ABOUT 3 TO 6 DEGREES WARMER THAN THE GRIDS ARE SHOWING. PLAN TO UPDATE AN BUMP TEMPERATURES UP BIT FOR THIS AFTERNOON. && .LONG TERM... TONIGHT...UPPER FLOW ACROSS THE NORTHERN U.S. IS PROGGED TO BECOME A BIT MORE ZONAL AS THE TROUGH IN THE PACIFIC NW STARTS PUSHING EAST. AS THIS OCCURS...THE SHRTWV CURRENTLY IN SW MONTANA IS PROGGED TO MOVE INTO NORTHERN MN BY 06Z AND INTO NORTHERN LAKE SUPERIOR BY 12Z MON. THIS SHRTWV SHOULD HELP PUSH THE UPPER RIDGE OVER UPPER MI EASTWARD...PLACING THE AREA IN A WARM ADVECTION ZONE IN THE LOW LEVELS. THIS WARM ADVECTION...COMBINED WITH THE SHRTWV MOVING IN...LIKELY MEANS THE DEVELOPMENT OF AN MCS SOMEWHERE IN THE WESTERN GREAT LAKES. LOCATION DEPENDS HIGHLY ON FAR NORTH THE CAP FROM THE HEAT RIDGE IN THE CENTRAL PLAINS MOVES NORTH...AS THE EDGE OF THIS CAP IS LIKELY WHERE THE MCS TRACKS ALONG. THE 00Z UKMET REMAINS CONSISTENT WITH MANY OF ITS PREVIOUS RUNS SHOWING DEVELOPMENT FROM CENTRAL MN INTO NRN WI AND UPPER MI...SINCE IT BRINGS 850MB TEMPS OF 20C OR GREATER TO A LINE FROM HINCKELY MN TO MADISON WI BY 06Z TUE. THE REGIONAL CANADIAN IS PRACTICALLY IDENTICAL TO THE UKMET. OUR LOCAL WRF-ARW RUNS ARE SIMILAR TO THE UKMET...ONLY A LITTLE SOUTH. THE 00Z NAM/ECMWF ARE FARTHER SOUTH...DEVELOPING THE MCS OVER SRN MN AND TRACKING IT EASTWARD INTO CENTRAL WI...WITH UPPER MI GETTING INTO THE NRN FRINGES OF THE PCPN FIELD. THE 00Z GFS IS SIMILAR TO OUR LOCAL WRF-ARW RUN...BUT SLOWER...TAKING AN MCS FROM CENTRAL MN INTO SRN UPPER MI BETWEEN 12-18Z MON. GIVEN THE DIFFERENCES...HAVE ONLY ENOUGH CONFIDENCE AT THIS POINT TO GO NO HIGHER THAN 50 POPS...GREATEST IN THE SOUTHERN U.P.. NEXT SHIFT CAN DETERMINE WHETHER TO RAISE POPS FURTHER ONCE MORE CERTAINTY DEVELOPS ON HOW FAR NORTH THE CAP LIFTS TODAY IN MN. WHEREVER THE MCS OCCURS...THERE WILL BE A POSSIBILITY FOR SEVERE WEATHER...WITH DAMAGING WINDS PROBABLY THE MAIN THREAT SINCE FREEZING LEVELS ARE QUITE HIGH (14500 FT OR HIGHER). SHOULD BE A WARM NIGHT...WITH READINGS IN THE LOW 60S. MONDAY...BASE OF UPPER TROUGH IN THE PACIFIC NW IS PROGGED TO SHIFT INTO SOUTH CENTRAL CANADA AND NORTH DAKOTA. THIS MEANS SOME WEAK RIDGING MAY GET BUILT UP OVER THE CWA THROUGH THE DAY...AND THUS PROVIDE SOME CAPPING AND SUBSIDENCE. THEREFORE...HAVE ADJUSTED THE FORECAST TO GO WITH LOWER POPS IN THE AFTERNOON. HOWEVER...THE MORNING FORECAST IS A BIT MORE TROUBLESOME AS IT HIGHLY DEPENDS ON THE LOCATION OF TONIGHTS MCS. FOLLOWING THE PREVIOUS DISCUSSION... HAVE WENT WITH HIGHER POPS IN THE SOUTHERN U.P. WHICH SHOULD BE CLOSE TO OR POSSIBLY ON THE MCS TRACK (NOTED BY THE 00Z GFS). ANOTHER REASON FOR LOWER POPS DURING THE AFTERNOON IS THAT THE AREA SHOULD HAVE A HARDER TIME HEATING UP DUE TO CLOUD COVER OFF THE MCS...NO MATTER WHERE THE MCS IS. GUIDANCE TEMPS COOLED DOWN...AND OUR LOCAL WRF-ARW RUN EVEN SHOWS HIGHS IN THE LOW 70S. THEREFORE... TWEAKED THE HIGHS DOWNWARD A FEW DEGREES. DID NOT WANT TO GO TOO LOW GIVEN THAT 850MB TEMPS IN THE AFTN ARE 14-16C...WHICH WITH ANY SUN COULD ALLOW SURFACE TEMPS TO RISE QUICKLY. ALTHOUGH TEMPS WERE COOLED...IT STILL LOOKS LIKE A BIT HUMID AS THE HIGHER DEWPOINTS OVER THE DAKOTAS SHIFT INTO UPPER MI. MON NIGHT...SHRTWV TROUGH OVER NORTH DAKOTA IS INDICATED TO MOVE INTO NRN MN AND NW ONTARIO...RESULTING IN HEIGHT FALLS OVER THE CWA THROUGH THE NIGHT. HAVE STILL LEFT IN SOME CHANCE POPS FOR THESE HEIGHT FALLS...BUT AM NOT OVERLY EXCITED ABOUT PCPN CHANCES GIVEN TIME OF DAY. MODELS REFLECT THIS BY SOME NOT GENERATING ANY QPF AND OTHERS ONLY SOME LIGHT QPF. TEMPS AGAIN SHOULD BE ON THE MILD SIDE GIVEN THE HIGHER DEWPOINTS THAT MOVED IN ON MONDAY. TUE...WEATHER IS LOOKING A BIT MORE INTERESTING. SHRTWV TROUGH IN NRN MN AND NW ONTARIO IS NOW PROGGED BY THE MODELS TO DIG DOWN INTO UPPER MI DURING THE AFTERNOON...AIDED BY ANOTHER SHRTWV CURRENTLY ON THE WEST SIDE OF THE TROUGH OVER BRITISH COLUMBIA. THIS DIGGING IS REPRESENTED BY 500MB HEIGHT FALLS OF ANYWHERE FROM 40 TO 80 METERS...AS INDICATED BY THE ECMWF/UKMET/NAM. GIVEN THE TIMING OF THE SHRTWV COMING DOWN DURING THE AFTERNOON...A SURFACE TROUGH MOVING THROUGH...DEWPOINTS STILL BEING HELD UP IN THE LOW TO MID 60S AHEAD OF THE TROUGH...AND SURFACE HEATING THAT WILL OCCUR DURING THE MORNING (HIGHS EXPECTED IN THE MID TO UPPER 70S AWAY FROM THE SHORELINES)...EXPECTING THAT SHOWERS AND THUNDERSTORMS TO DEVELOP DURING THE AFTERNOON. CONFIDENCE IS HIGH ENOUGH AT THIS POINT TO INCLUDE COVERAGE WORDING. IN ADDITION...WITH 0-6KM BULK SHEAR OF 40-45 KT AND MLCAPE VALUES OF 1000-1500 J/KG...SOME SEVERE WEATHER SEEMS POSSIBLE. HAIL MAY NOT BE THAT GREAT OF HAZARD WITH HIGH FREEZING LEVELS AGAIN...HOWEVER HIGH SURFACE TO 10000 FT DELTA THETA-E VALUES (AROUND 25) AS A RESULT OF DRY MID-LEVEL AIR MOVING IN SUGGESTS A DEFINITE ISSUE FOR WIND. SEVERE RISK SHOULD BE CONFINED TO THE CENTRAL U.P. AS THE WESTERN U.P. STARTS DRYING OUT WHEN THE SHRTWV MOVES IN. SPC DAY3 OUTLOOK HAS THE CENTRAL/EASTERN U.P. IN A SEVERE RISK. TUE NIGHT AND WED...DRYING WILL COME INTO THE CWA TUE NIGHT BEHIND TUE AFTNS SHRTWV. THEREFORE GOING DRY FORECAST IS ON TRACK. IN ADDITION...COOLER TEMPS WILL ALSO MOVE IN. WAS TEMPTED TO LEAVE THE FORECAST DRY FOR WED AS WELL...HOWEVER THERE ARE INDICATIONS OF ANOTHER SHRTWV DIVING THROUGH UPPER MI AS THE BEGINNINGS OF AN UPPER TROUGH FORM OVER SE CANADA INTO THE GREAT LAKES. BOTH THE ECMWF AND GFS SHOW THIS SHRTWV...BUT ONLY THE GFS PRODUCES PCPN. THE PCPN AREA IS CONFINED TO THE CENTRAL U.P. DURING THE AFTN DUE TO LAKE BREEZE CONVERGENCE. MODIFIED SOUNDING FROM THE AREA WHERE PCPN IS PRODUCED TO REMOVE THE HIGH SURFACE DEWPOINT BIAS STILL SUGGESTS AROUND 500 J/KG (INSTEAD OF THE 900 J/KG). THEREFORE HAVE WENT AHEAD AND INCLUDED A 20 POP. OTHER PCPN MAY MOVE INTO WESTERN LAKE SUPERIOR DURING THE AFTN OFF THE MN ARROWHEAD ASSOCIATED WITH ANOTHER SHRTWV. GOING TEMP FORECAST FOR WED SEEMED REASONABLE. NO OTHER CHANGES MADE BEYOND WED. STILL LOOKS LIKE UNSEASONABLY COOL WEATHER TO MOVE IN TOWARDS THE END OF THE WEEK AS 850MB TEMPS DROP TO 6-8C. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... VFR CONDITIONS WILL PERSIST UNTIL TONIGHT WHEN CONVECTION WILL COME IN. WITH THE HEAVIER RAIN ARRIVING...THINK VIS WILL GO MVFR WITH SOME FOG AND PUT IN BOTH SITES WITH CIGS STAYING VFR. MENTIONED CB GROUP IN TAFS AND NOT THUNDER AT THIS TIME. WHEN EVENT DRAWS CLOSER...THUNDERSTORMS CAN BE INCLUDED WHEN TIMING IS A BIT MORE CERTAIN AND ALSO BECOMES MORE CERTAIN HOW THIS EVENT WILL UNFOLD. THERE IS A CHANCE THAT CONVECTION WILL GO AROUND THE AREA INSTEAD...SO CONFIDENCE NOT HIGH ENOUGH TO PUT TSRA IN TAFS YET. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... TRICKY FORECAST FOR THE NEXT SEVERAL DAYS IN REGARDS TO CONVECTION AND WHAT IT WILL DO WITH THE WINDS. GFS SUFFERS CONVECTIVE FEEDBACK ISSUES AND TRIED TO STAY AWAY FROM IT AND WENT CLOSER TO THE NAM FOR WINDS AS NO CONVECTIVE FEEDBACK PROBLEMS WITH IT. SPEEDS SHOULD STILL REMAIN AT OR BELOW 20 KTS WITH WEST TO NORTHWEST WINDS UP TO 20 KT ON TUE IN THE WAKE OF A TROUGH. NAM IS A BIT STRONG ON WINDS THEN AND KNOCKED THEM DOWN A BIT. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM...DLG LONG TERM...AJ AVIATION...ROLFSON MARINE...GM mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DULUTH MN 1111 AM CDT SUN AUG 3 2008 .UPDATE... FCST STILL ON TRACK. UPDATED ZFP FOR TIME REFERENCES. ALSO ISSUED SML CRAFT ADVY FOR HEAD OF THE LAKE THRU THIS EVE FOR STRONGER ONSHORE WINDS. && .PREV DISCUSSION... /ISSUED 337 AM CDT SUN AUG 3 2008/ DISCUSSION...MAIN FOCUS OVER THE NEXT FEW DAYS WILL BE RESOLVING INDIVIDUAL PRECIPITATION EVENTS. QUIET ACROSS THE CWA THIS MORNING WITH THE RUC INDICATING A WEAK SHORTWAVE MOVING THROUGH THE CWA. THERE WAS A FAIR AMOUNT OF AC/CI STREAMING THROUGH...ESPECIALLY ACROSS THE NORTHERN HALF OF THE CWA. TEMPS WERE WARMER THAN THE PREVIOUS NIGHT WITH MOST LOCATIONS IN THE 50S AND 60S. SEVERAL MCS/S HAD DEVELOPED IN MONTANA AND THE NORTHERN PLAINS EARLY THIS MORNING...HEADING EAST. SOME FAIRLY IMPRESSIVE STORMS OUT THERE...WITH STRONG WINDS. THE 4KM WRF-NMM SIMULATED REFLECTIVITY PRODUCT ACTUALLY DID A PRETTY GOOD JOB PINPOINTING THE DEVELOPMENT OF THIS MCS...ALTHOUGH IT DID NOT HANDLE CONVECTION FURTHER SOUTH IN NEBRASKA. THE H5 RIDGE BUILDING INTO THE UPPER MIDWEST/WESTERN GREAT LAKES WILL GRADUALLY BREAK DOWN AND FLATTEN DUE TO SHORT WAVE ENERGY MOVING IN FROM THE WEST TODAY AND TONIGHT. THE MODELS ARE HAVING A HARD TIME LATCHING ONTO SPECIFIC SHORTWAVE ENERGY...AND THE EVOLUTION OF CONVECTION AND MCS ACTIVITY WILL BE TRICKY TO PINPOINT THROUGH EARLY IN THE WORK WEEK. WILL HAVE TO GO MAINLY WITH TRENDS AND ASSESSMENT OF MASS FIELDS IN DETERMINING POPS AND QPF. HAVE CLOSELY FOLLOWED HPC QPF WITH SOME EXCEPTIONS. FOR TODAY...WILL HIT THE SW 1/3 OF THE CWA HARDEST THIS MORNING. THE 4KM WRF-NMM SIMULATED REFLECTIVITY INDICATES THAT THE MCS ACTIVITY IN THE DAKOTAS WILL GRADUALLY MIGRATE EASTWARD INTO THE CWA...FIRST REACHING THE WESTERN PORTION OF THE CWA...AND THEN SPREADING ACROSS THE REMAINDER OF THE CWA. WE COULD SEE SOME WEAKENING/DIMINISHING OF THE ACTIVITY AS IT MOVES INTO THE WESTERN GREAT LAKES...WITH SOME REDEVELOPMENT PERHAPS TAKING PLACE AS IT DOES. THE BIG QUESTION IS THE IMPACT CONVECTIVE DEBRIS WILL HAVE ON SURFACE HEATING TODAY. THINK THE BEST CHANCE FOR SOME SURFACE HEATING AND DESTABILIZATION WILL BE IN THE SOUTHERN AND WESTERN PORTIONS OF THE CWA DURING THE AFTERNOON/EVENING. SPC HAS MUCH OF THE SOUTHERN HALF OF THE CWA IN A SLIGHT RISK AND THINK THIS LOOKS REASONABLE IF SOME HEATING CAN OCCUR. WILL GO WITH 30/40 POPS TODAY BUT WILL HAVE TO WATCH CONVECTION IN THE DAKOTAS...IN THE EVENT IT DOES NOT DIMINISH AS PROGGED. GFS ENSEMBLE MEMBERS ARE ACTUALLY IN DECENT AGREEMENT ON BRINGING PRECIPITATION NEARLY CWA- WIDE THIS AFTERNOON. HIGH TEMPS TODAY WILL BE TRICKY DUE TO POTENTIAL FOR CLOUD COVER...BUT WILL GO FAIRLY CLOSE TO MOS. FOR TONIGHT...THINK THERE IS DECENT POTENTIAL FOR MCS DEVELOPMENT AS THE SURFACE LOW IN THE DAKOTAS MOVES INTO SOUTHERN MINNESOTA OVERNIGHT. THE DEVELOPMENT OF A STRONG LLJ WITH IMPRESSIVE LOW LEVEL MOISTURE AND PRECIPITABLE WATER VALUES OVERRIDING THE FRONT WILL COMBINE WITH SHORTWAVE ENERGY TO GENERATE SOME MCS ACTIVITY. WILL INCREASE POPS INTO THE LIKELY CATEGORY FOR THE SOUTHERN 1/3 OF THE CWA TONIGHT. GFS ENSEMBLE MEMBERS ARE FAIRLY SPREAD APART BUT BASED ON THE MASS FIELDS AND THE POSITION OF THE SURFACE LOW/LLJ...WILL INCREASE POPS ANYWAY. COULD STILL BE A FEW SEVERE...ESPECIALLY IN THE SOUTHERN HALF/THIRD OF THE CWA. MONDAY AND MONDAY NIGHT SHOULD CONTINUE TO BE FAIRLY UNSETTLED. WILL CONTINUE WITH LOW POPS AT THIS POINT...BUT WILL HAVE TO WATCH THE SITUATION CLOSELY IN THE EVENT THERE ARE SOME MCS/S. BEST CHANCE WOULD LIKELY BE IN THE SOUTHERN THIRD OF THE CWA. LONG TERM...TUESDAY THRU SATURDAY... AS WAS MENTIONED AT THIS TIME YDAY..THE LATEST MODEL SOLUTIONS SEEM TO BE TRENDING SLIGHTLY SLOWER WITH THE EASTWARD PROGRESSION OF THE FRONT MON-TUE WITH SUCCESSIVE RUNS..BUT FOR THIS EXTENDED PERIOD IT APPEARS THAT THE INSTABILITY AXIS WILL BE SHUNTED MOSTLY SE OF THE DLH CWA BY TUESDAY. WE HAVE RETAINED SOME LOW POPS DURING THE DAY TUESDAY FOR NOW..BUT WE HAVE KEPT A DRY FORECAST IN PLACE TUE NITE/WED AS LOW LEVEL RIDGING IS PROGGED TO BUILD SWD INTO THE WRN LAKES REGION. FOR THE WED NITE-SAT TIME FRAME...WHILE DIFFERING ON THE DAY TO DAY DETAILS..MOST MEDIUM RANGE GUIDANCE IS STILL CONSISTENT WITH PREVIOUS RUNS IN THE GRADUAL EVOLUTION OF AN ERN CONUS TROF AND RESULTANT LOW LEVEL RIDGING BUILDING OVER ONTARIO TO THE NORTH OF LAKE SUPERIOR LATE THIS WEEK AND INTO THE WEEKEND. SUCH A PATTERN WOULD MOST LIKELY RESULT IN ANY SIGNIFICANT INSTABILITY BEING DISPLACED WELL TO THE SOUTHWEST OF THE DLH CWA..WITH COOL AND RELATIVELY DRY N/NE LOW LEVEL TRAJECTORIES. HENCE..WE HAVE REMOVED MENTION OF PRECIP FRI/SAT AND COOLED TEMPS SLIGHTLY WITH THIS FORECAST ISSUANCE..ESPECIALLY IN CLOSER PROXIMITY TO LAKE SUPERIOR. AVIATION...SIMILAR AVIATION CONCERNS THIS PERIOD TO THE PAST 24 HOURS OR SO. MID/HIGH LEVEL CLOUDS RESULTING FROM CONVECTIVE DEBRIS TO OUR WEST AND NORTHWEST. HOWEVER..CLOUDS ARE THIN ENUF TO ALLOW FOR SIGNIFICANT RADIATIONAL COOLING AGAIN THIS MORNING..AND SOME FOG HAS FORMED IN FAVORED LOW LYING TERRAIN AREAS INCLUDING HAYWARD AND HIBBING..WHICH WILL LIKELY PERSIST UNTIL 13-14Z. ALSO..LOW LEVEL JET IS STRONGER THIS MORNING AND HAVE INCLUDED A MENTION OF LOW LEVEL WIND SHEAR FOR WIND SPEED/DIRECTION CHANGE OF GREATER THAN 20 KTS/20 DEGREES WITHIN 2KFT OF SURFACE. CHANCE FOR TSTORMS WILL INCREASE BETWEEN 15-18Z IN KBRD AND 17-19Z IN KHIB/KDLH/KHYR. && POINT TEMPS/POPS... DLH 72 59 79 58 / 30 50 30 30 INL 79 58 80 56 / 30 40 20 30 BRD 83 61 83 59 / 40 60 20 30 HYR 80 61 85 59 / 30 60 30 30 ASX 79 60 79 59 / 30 50 30 30 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...SMALL CRAFT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR LSZ144- LSZ145. $$ 04/GRANING mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBUQUERQUE NM 1014 AM MDT SUN AUG 3 2008 .UPDATE... RAISED POPS OVER THE HIGHER TERRAIN OF THE CENTRAL MTN CHAIN THIS AFTERNOON INTO THIS EVENING IN LINE WITH RUC13...09Z SREF...12Z MET/MAVMOS. MORNING RAOB FROM EPZ TO ABQ SHOWS BIG INCREASE IN MOISTURE ACROSS THE REGION WITH LOTS OF INSTABILITY TO WORK WITH. STORMS WILL NOT MOVE MUCH COMBINE WITH PWATS AROUND 1 INCH...SO LOCALLY HEAVY RAINFALL NOT OUT OF THE QUESTION. THE UPPER LEVEL WAVE MOVING NORTH OUT OF SOUTHERN NM SHOULD ALSO HELP TRIGGER CONVECTION. GUYER && .PREV DISCUSSION...253 AM MDT SUN AUG 3 2008... CURRENTLY...RIDGE ALOFT ACROSS SOUTHERN HALF OF THE U.S. CENTERED UP ON NEW MEXICO WITH ASSOCIATED SURFACE RIDGE EXTENDING FROM WESTERN COLORADO TO SOUTH CENTRAL PORTIONS OF THE STATE. WESTBOUND SHORTWAVE PROPAGATING ALONG SOUTHERN MARGINS OF THE RIDGE...WITH ANOTHER NIGHT OF PRECIPITATION ENHANCEMENTS FROM WEST TEXAS THROUGH WESTERN SONORA STATE AND INTO THE GULF OF CALIFORNIA. MODELS...HANGING TOGETHER REASONABLY IN A LOW FLOW REGIME WITH LITTLE DYNAMICAL ACTION. BROAD CONSENSUS MOVES RIDGE CORE EASTWARD VERY SLOWLY THROUGH FIRST HALF OF THE WORK WEEK...AND THEN RETURNS THE CORE TO THE FOUR CORNERS REGION FOR THE LAST HALF HALF OF THE WORK WEEK...AND ANOTHER WOBBLE BACK TO THE EAST FOR THE UPCOMING WEEKEND. GFS BRINGING ANOTHER TROPICAL DISTURBANCE...CURRENTLY LABELED INVEST 91 AND PRESENTLY OFF MOBILE BAY...WESTWARD ACROSS SOUTH TEXAS WITH MOISTURE GRADUALLY WORKING INTO EASTERN ARIZONA BY NEXT WEEKEND...AND SPILLING FURTHER EAST INTO NEW MEXICO EARLY IN THE FOLLOWING WORK WEEK. MUCH UNCERTAINTY REMAINING WITH THIS TRACK...AND EUROPEAN CENTER MODEL FOR ONE KEEPS MUCH OF THE RESULTING PRECIPITATION WELL TO THE WEST IN ARIZONA WITH NEW MEXICO MAINLY IN THE DRY. STAY TUNED...AS FUTURE RUNS WILL HAVE MUCH TO SAY ON HOW INVEST 91 IS HANDLED FOR NEXT WEEKEND. SHORT TERM...TODAY AND TONIGHT...A FEW SHOWERS AND THUNDERSTORMS GETTING GOING TODAY...ESPECIALLY OVER THE SOUTHWEST AND WEST CENTRAL MOUNTAINS. A FEW THUNDERSTORMS WILL GET STARTED OVER THE SACRAMENTOS AND GUADALUPE MOUNTAINS...AND THE SANGRE DE CRISTO MOUNTAINS AS WELL THIS AFTERNOON...AS CORE OF RIDGE ALOFT STARTS TO CREEP SLOWLY EASTWARD. HEAVIEST SHOWERS WILL BE NEAR THE ARIZONA BORDER. TEMPERATURES REMAINING BROADLY ABOVE SEASONAL NORMS FOR EARLY AUGUST. LINGERING SHOWERS TONIGHT MAINLY OVER THE WESTERN AND SOUTHWESTERN MOUNTAINS...AND THE SANGRE DE CRISTOS...AS SURFACE LOW DEEPENS OVER NORTHEAST CORNER OF THE STATE IN WAKE OF RETREATING RIDGE ALOFT. LONG TERM...MONDAY THROUGH WEDNESDAY...SURFACE LOW COILING UP OVER EASTERN COLORADO WITH SOUTH AND SOUTHWEST FLOW KEEPING LOW LEVEL MOISTURE ACTIVE OVER THE STATE WILL INCREASE CLOUD COVERAGE FROM SOUTH TO NORTH ON MONDAY WITH BROAD INCREASE IN SHOWER COVERAGE FROM THE CENTRAL MOUNTAIN CHAIN WEST TO THE ARIZONA BORDER...WITH HEAVIEST RAINFALL AGAIN SETTING UP NEAR THE COPPER STATE FOR THE DAY ON MONDAY. EXTRA CLOUD COVER ON MONDAY WILL HELP LIMIT UPSWINGS IN MAXIMUM TEMPERATURES FOR THE DAY. LINGERING SHOWERS MAINLY ALONG THE WESTERN BORDER THROUGH MONDAY EVENING. INTO TUESDAY...RIDGE CORE SETTING UP OVER SOUTHERN KANSAS AS SURFACE LOW BENEATH WESTWARD PROPAGATING SHORTWAVE TAKES UP RESIDENCE OVER NORTHEAST SONORA STATE. AUGMENTED MOIST FLOW NORTHWARD WILL MEET UP WITH WEAK DYNAMICS CIRCULATING ABOUT THE WESTERN MARGINS OF THE DEPARTING RIDGE FOR ANOTHER BOOST IN SHOWER COVERAGE FROM THE CENTRAL MOUNTAINS WEST TO THE ARIZONA BORDER...AND COVERAGE EXPANDING INTO THE NORTHEAST HIGHLANDS AND NORTHEAST PLAINS BY TUESDAY AFTERNOON. MORE AND THICKER CLOUD COVER WILL FLATTEN HIGH TEMPERATURES NEAR SEASONAL LEVELS THIS ROUND...WITH A FEW DEGREES ABOVE NORMAL RUNNING IN THE SUNSHINE ACROSS THE EASTERN AND SOUTHEASTERN PLAINS. INTO WEDNESDAY...TRANSITION DAY AS RIDGE CENTER STARTS BUILDING OVER THE FOUR CORNERS...AND DEEPENING SURFACE TROUGH OVER EASTERN NEW MEXICO WILL HELP BACK WINDS TO SOUTHEAST FOR YET ANOTHER UPTICK AND COVERAGE EXPANSION OF SHOWERS FOR THE DAY. WILL STILL BE TOUGH TO GET TOO MUCH COVERAGE TO THE EASTERN AND SOUTHEASTERN PLAINS...BUT WESTERN AND NORTHERN AREAS WILL PICK UP YET ANOTHER DAY OF AFTERNOON THUNDERSTORMS. MAX TEMPERATURE FOR THE DAY WILL BE PRETTY MUCH A REPEAT OF TUESDAY. SHY .AVIATION... ISOLATED SHOWERS AND THUNDERSTORMS WILL FAVOR THE WESTERN TWO THIRDS OF THE STATE...INITIATING ON THE HIGH TERRAIN AND MOVING SLOWLY AND ERRATICALLY. A FEW STRAY SHOWERS AND STORMS ARE POSSIBLE IN THE EAST CENTRAL TO SOUTHEASTERN PLAINS...BUT ANY DEVELOPMENT IN THIS AREA IS EXPECTED TO BE VERY ISOLATED AND SHORT LIVED. GUSTY OUTFLOW WINDS WILL BE THE MAIN THREAT...AND CONVECTION COULD CARRY ON INTO THE LATE EVENING HOURS DUE TO AN APPROACHING UPPER LEVEL DISTURBANCE FROM THE SOUTH. NEXT AVIATION DISCUSSION SCHEDULED FOR 21Z. 52 .FIRE WEATHER... UPPER LEVEL HIGH PRESSURE WILL CONTINUE TO NUDGE EAST OF NEW MEXICO AND WILL GRADUALLY OPEN UP THE DOOR TO SOME MID LEVEL MOISTURE FROM THE SOUTH. AN EMBEDDED DISTURBANCE WILL ALSO SLOWLY MAKE ITS WAY INTO THE SOUTHERN PORTIONS OF THE STATE THROUGH MONDAY. THIS OVERALL SCENARIO WILL ALLOW STORMS TO INCREASE SLIGHTLY IN COVERAGE THROUGH MONDAY AND TUESDAY. FOR TODAY...STORMS WILL GENERALLY FAVOR THE WESTERN TWO THIRDS OF THE STATE...PARTICULARLY INTO SOUTH CENTRAL AREAS. STORMS WILL STILL REMAIN ISOLATED TODAY...WHILE HUMIDITIES DECLINE BELOW 20 PERCENT IN MANY LOCALES NEAR AND NORTH OF INTERSTATE 40...AND NEAR SINGLE DIGIT HUMIDITIES ARE REACHED IN THE NORTHWEST. STORMS COULD BEGIN INCREASING IN COVERAGE AS EARLY AS THIS EVENING AND MORE SO ON MONDAY. THROUGH MID WEEK DEWPOINTS AND HUMIDITIES WILL ALSO SLOWLY RESPOND/INCREASE SOME TO ADDITIONAL STORMS...AND TEMPERATURES WILL COOL A COUPLE OF DEGREES IN MANY PLACES. LOCALIZED GUSTY OUTFLOW WINDS FROM THUNDERSTORMS WILL BE THE ONLY WIND CONCERN. 52. && .PRELIMINARY POINT TEMPS/POPS UPDATE... FARMINGTON...................... 97 64 95 64 / 5 10 5 5 GALLUP.......................... 90 58 88 58 / 20 20 20 20 GRANTS.......................... 91 57 89 57 / 10 20 20 10 GLENWOOD........................ 93 63 91 62 / 50 50 30 20 CHAMA........................... 85 48 84 49 / 20 20 20 20 LOS ALAMOS...................... 86 59 84 60 / 20 30 10 10 RED RIVER....................... 79 46 78 47 / 30 30 20 20 TAOS............................ 90 54 89 54 / 20 30 10 10 SANTA FE........................ 90 58 88 57 / 20 30 10 10 SANTA FE AIRPORT................ 92 61 90 61 / 10 30 10 10 ESPANOLA........................ 94 59 92 58 / 20 30 10 10 ALBUQUERQUE HEIGHTS............. 95 69 93 69 / 5 30 10 10 ALBUQUERQUE VALLEY.............. 95 66 93 65 / 0 20 10 10 ALBUQUERQUE FOOTHILLS........... 91 63 89 63 / 5 30 10 10 ALBUQUERQUE WEST MESA........... 95 64 92 65 / 5 20 10 10 SOCORRO......................... 93 65 91 64 / 5 20 5 5 SANDIA PARK/CEDAR CREST......... 85 55 81 56 / 5 30 10 10 MORIARTY/ESTANCIA............... 89 58 88 57 / 10 30 10 10 CARRIZOZO....................... 90 62 89 61 / 10 20 10 10 RUIDOSO......................... 82 57 80 55 / 20 20 20 10 RATON........................... 92 56 91 57 / 20 20 10 5 LAS VEGAS....................... 87 57 86 56 / 20 20 10 10 ROY............................. 89 62 89 62 / 5 10 5 5 CLAYTON......................... 95 66 94 65 / 0 5 0 5 SANTA ROSA...................... 95 63 94 62 / 0 5 0 5 TUCUMCARI....................... 98 69 97 67 / 0 5 0 0 FORT SUMNER..................... 94 67 94 66 / 0 5 0 0 CLOVIS.......................... 96 67 96 66 / 0 0 0 0 PORTALES........................ 96 68 96 67 / 0 0 0 0 ROSWELL......................... 98 70 98 70 / 0 5 0 0 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$ GUYER nm AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 1034 AM EDT SUN AUG 3 2008 .SYNOPSIS... LOW PRESSURE OVER NEW ENGLAND WILL KEEP THE CHANCE OF SHOWERS AND THUNDERSTORMS OVER THE AREA TODAY AND TONIGHT. HIGH PRESSURE WITH DRIER AIR OVER THE MIDWEST WILL MOVE INTO THE AREA FOR MONDAY AND TUESDAY. && .NEAR TERM /TODAY/... AS OF 1030AM...LOTS OF CLOUDINESS THIS MORNING AS COOL TEMPS ALOFT COMBINED WITH SOME WEAK LLEVEL HEATING...AND MOIST UPLOPE NW FLOW OVER MUCH OF THE CWA. SHRA HAVE EXPANDED IN COVERAGE SOME THIS MORNING AS WELL...BRINGING A SOMEWHAT RAW FEEL TO THIS EARLY AUGUST MORNING. TEMPS ALOFT WILL GRADUALLY WARM AS THE DAY PROGRESSES...BUT EXPECT MOST SPOTS WILL SEE MORE CLOUDS THAN SUN. CONVECTIVE POTENTIAL LOOKS MINIMAL GIVEN THE LACK OF SURFACE HEATING. THE NAM/RUC SUGGEST A SMALL WINDOW BY MID AFTERNOON OF SOME SKINNY CAPE DEVELOPING. HOWEVER...THE RUC QUICKLY SHUTS THE DOOR WITH A DEVELOPING SUBSIDENCE INVERSION AS HEIGHTS RISE BY LATE AFTERNOON. SO...EXPECT MOSTLY SHRA WITH A FEW EMBEDDED TSRA POSSIBLE THIS AFTERNOON. TEMPS WILL STRUGGLE INTO THE 70S GIVEN T850 AROUND +11-12C AND NOT QUITE FULL MIXING GIVEN THE AMOUNT OF CLOUDINESS AROUND. PREVIOUS PACKAGE HAD A GOOD HANDLE ON THIS AND HAVE ONLY HAD TO MAKE MINOR TWEAKS TO WORDING FOR THE AFTERNOON. UPDATED GRIDS/PRODUCTS ARE OUT. PREVIOUS DISCUSSION FOLLOWS... UA LOW PARKED OVER VERMONT WILL KEEP A COOL POOL ALOFT...AND A NORTH FLOW OF MID LVL MOISTURE OVER THE AREA TODAY. THE MOISTURE AND INSTABILITY WILL CONT THE RISK OF RW AND TRWS...ESP OVER THE NERN PARTS OF THE FCST AREA. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... UA LOW SLOWLY LIFTS EWRD TO BE OFF THE ME CST BY 12Z MON. THIS WILL ALLOW A GRADUAL RETURN OF DRIER AIR...AND SFC RDGG...OVER THE AREA. STILL...ENUF MOISTURE AND INSTABILITY TO KEEP THE THREAT OF SHWRS AND TRWS FOR MUCH THE 2ND PD OVER THE NRN HALF OF THE FCST AREA. DESPITE SFC RDGG AND THE RETURN OF DRY AIR...OVERALL PTRN OF A BROAD TROF OVER THE NE CONTS AS THE RECORD HEAT UNDER THE PLAINS RDG CONTS. THIS WILL KEEP OUR AREA MORE COMFORTABLE BUT PRONE TO SHRT WVS ZIPPING THRU THE UPR FLOW. GFS APPEARS TO BE SUFFERING FROM SOME CONV FEEDBACK...OVER DVLPG A SFC LOW AND SHRT WV ON TUE BUT IT/S DFCLT TO RULE OUT SHWRS JUST ABOUT ANYTIME IN THIS PTRN. FOR NOW...WILL IGNORE THE GFS SOLN FOR TUE AND KEEP THE REMAINDER OF THE PD DRY. NEXT BEST SHRT WV LOOKS TO APRCH THE AREA IN THE XTNDD PD. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... DEEP EAST COAST TROFFING STILL BEING ADVERTISED BY END OF THE WEEK. CONTINUITY APPEARS TO BE THE BEST SOLN IN THIS CASE AS INDIVIDUAL S/WVS WILL BE EXTREMELY HARD TO GET A HANDLE ON UNTIL CLOSER IN TIME. HV KEPT ONLY SLGT POPS IN WED NGT/THUR UNDER TRANSITORY FLOW. AFT THAT POINT...CANNOT RULE OUT SCTD PCPN ANY PD THRU RMNDR OF THE LONG TERM. CURRENT FCST CAPITALIZES ON THESE TRENDS AND HV MADE VRY FEW TWEAKS TO EXTNDD DRG THIS TIMEFRAME. && .AVIATION /15Z SUNDAY THROUGH THURSDAY/... MVFR AT MOST LOCATIONS THIS MRNG...WITH LCL IFR ON THE HILLTOPS AND AT RME. OVERALL...CIGS ARE XPCTD TO LIFT BY THIS AFTN TO VFR...BUT MVFR COULD PERSIST INTO THE AFTN AT A FEW CNTRL NY LOCATIONS. SCT --SHRA THIS MRNG WITH PSBLTY OF -TSRA THIS AFTN....BUT PROBS DEEMED TO LOW AT THIS POINT TO INCLUDE IN TAFS. BECT CHC APPEARS TO BE AT RME AND WILL UPDATE IF NEEDED. GNRLY VFR XPCTD TNGT...BUT PROFILES ONCE AGAIN SUGGEST PSBLTY OF MVFR CIGS LATE...ALTHO THEY SHUD BE RESTRITED TO UPSTATE NY. WINDS TDA NW ARND 10 KTS...WITH G15-20 PSBL THIS AFTN..BCMG LGT THIS EVNG. SUN NGT THRU MON NGT...VFR BUT POTNL FOR DENSE EARLY MRNG VLY FOG AT ELM. TUES THRU WED NGT...POTNL FOR SCT MVFR IN TSRA. THU...CONDS IMPRV TO VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DGM NEAR TERM...JMA/DGM SHORT TERM...DGM LONG TERM...PVB ny AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GRAND FORKS ND 1036 AM CDT SUN AUG 3 2008 .DISCUSSION...MAIN CHALLENGE FOR TODAY WILL BE CONVECTION/SEVERE POTENTIAL. VERY COMPLEX SCENARIO UNFOLDING AND STILL MORE QUESTIONS THAN ANSWERS AT THIS POINT. 12Z NAM/RUC DO OFFER A BIT OF INSIGHT. CURRENTLY AREA OF SHOWERS WITH EMBEDDED THUNDER MOVING FROM W TO E ACROSS THE FA ASSOCIATED WITH SHORTWAVE NOW ACROSS E ND. EXPECT MUCH OF THIS ACTIVITY TO CONTINUE EASTWARD MOVEMENT...EXITING FA BY 18Z. THIS SHOULD LEAVE MUCH OF THE FA WITH AT LEAST PARTLY SUNNY SKIES. WATER VAPOR IMAGERY...AND 12Z NAM/RUC SUGGEST AN ADDITIONAL WAVE ACROSS WYOMING WHICH SHOULD CONTINUE NE PROPAGATION AND LIFT SFC-850MB LOW (CURRENTLY ACROSS CENTRAL/E SD) A BIT NORTHWARD. BY 18Z...30-40KT 850MB JET WILL SET UP ACROSS THE SE FA WITH 850MB CAPE INCREASING TO NEAR 2000 J/KG. THIS WILL BE THE FIRST AREA NEEDED TO WATCH FOR SEVERE POTENTIAL...ALTHOUGH CURRENT RADAR IMAGERY SUGGESTS THIS MAY BE OCCURRING JUST E OF THE FA. MID-LATE AFTERNOON SEVERE POTENTIAL WILL DEPEND UPON HOW MUCH INSTABILITY WILL BE AVAILABLE. 12Z MODEL GUIDANCE IS A BIT STRONGER WITH INVERTED TROUGH/WIND SHIFT LINE WHICH WILL MOVE FROM WEST TO EAST ACROSS THE FA. MODELS SUGGESTING MLCAPE VALUES AT LEAST 1000 J/KG E OF THE VALLEY BY MID- AFTERNOON...WHICH COULD BE SUFFICIENT FOR A FEW SEVERE STORMS GIVEN STRONG DEEP LAYER SHEAR. MID-LEVEL TEMPS DO COOL ACROSS MUCH OF THE FA (EXCEPT THE FAR SOUTH) SO CAPPING WITH THIS TROUGH PROBABLY NOT AN ISSUE. BIGGEST QUESTION WITH THIS SCENARIO WILL BE CLOUD COVER AND INSTABILITY. CURRENT GRIDS LOOK REASONABLE GIVEN UNCERTAINTIES. IF DETAILS BECOME MORE CLEAR NEXT FEW HOURS WILL SEND ANOTHER UPDATE AND INCLUDE SEVERE MENTION IF WARRANTED. && .AVIATION...PRIMARY VFR WITH PASSING CONVECTION TODAY. ALWAYS A CHANCE FOR GUSTY WINDS AND MVFR VSBY/CIGS IN STRONGER STORMS. && .PREV DISCUSSION... /ISSUED 230 AM CDT SUN AUG 3 2008/ DISCUSSION... FORECAST CHALLENGE WILL BE CONVECTIVE POTENTIAL NEXT TWO DAYS ALONG WITH TEMPERATURES. WILL USE BLEND AS PREFER SFC/MOISTURE FEATURES WITH NAM EARLY THEN GFS FOR LATER PERIODS AS NAM SEEMS TOO ROBUST WITH QPF MONDAY WITH SAGGING BAROCLINIC ZONE. NEXT WAVE LIFTING ENE OVER NORTHERN HIGH PLAINS COMBINING WITH WELL DEFINED SURFACE CIRCULATION OVER SE MT...CONVERGENCE WITH ELEVATED FLOW...SUFFICIENT DEEP LAYERED RH AND 60-70 DEGREE SFC DEWPOINTS RESULTING IN ORGANIZING TSRA COMPLEX CURRENTLY OVER NW SD/SW ND ON FRINGE OF CAP. AM ALSO SEEING CONVECTION ORGANIZING ALONG COLD FRONT FARTHER NORTH OVER E MT. GREATEST INSTABILITY INITIALLY IS OVER SD WITH AIRMASS FAIRLY STABLE FARTHER NORTH. FAR SOUTHERN FA ALSO CLOSER TO FAVORED CONVERGENCE WITH 850MB FLOW AND ON FRINGE OF MID LEVEL CAP. AS A RESULT WILL HAVE HIGHEST POPS ACROSS FAR SOUTH. FARTHER NORTH AIRMASS GRADUALLY DESTABILIZES DURING DAY AND AS COLD FRONT SHIFTS INTO THE CENTRAL DAKOTAS FEEL SOME REMNANTS OF CURRENT CONVECTION OVER E MT WILL PROPAGATE THROUGH REMAINDER OF FA AS WAVE PUSHES THROUGH AND REGION UNDER FAVORABLE ENHANCE BROADSCALE LIFT WITH JET MAXIMA. CLOUDS WILL LIMIT TEMPERATURE RECOVERY TODAY AND WILL STAY CLOSE TO GUIDANCE WHICH IS IN EXCELLENT AGREEMENT. SEVERE POTENTIAL TONIGHT SOMEWHAT IN QUESTION. INSTABILITY/CAPE LIMITED AND CONVERGENCE WITH SURFACE BOUNDARY VERY WEAK. IF CURRENT CONVECTION OVER WESTERN DAKOTAS/E MT PROPAGATES THROUGH FA DURING DAY NOT SURE IF AIRMASS WILL BE ABLE TO RECOVER. WITH LACK OF CONFIDENCE WILL NOT MENTION SEVERE BUT AFTER YESTERDAY CANNOT RULE OUT POSSIBILITY. NAM WHICH IS HANDLING SFC DEWPOINTS PRETTY WELL KEEPS 60 DEWPOINTS ACROSS ALL BUT NW FA EVEN THOUGH COLUMN COOLS ALOFT. WILL JUMP OVER TO GFS SOLUTION MONDAY. MODELS GENERATE PLENTY OF QPF OVER NORTHERN HIGH PLAINS WITH NEXT WAVE INTERACTING WITH SHARP BAROCLINIC ZONE AND FRONTOGENETIC FORCING. BAROCLINIC ZONE THEN SHIFTS SOUTH THROUGH SD DURING DAY AS WAVE CROSSES. AS A RESULT PREFER GFS SOLUTION VS NAM WHICH TRACKS MAIN PCPN TRACK DUE EAST ACROSS FA AND WILL CONTINUE WITH SLIGHT CHANCE POPS. COLUMN DOES NOT COOL A GREAT DEAL SO DEPENDING ON CLOUDS TEMPERATURES COULD REBOUND CLOSE TO NORMAL. HIGH BUILDS IN MONDAY NIGHT SO DECREASING RAIN CHANCES FROM N-S LOOKS GOOD. MORE SIGNIFICANT COOLING SPREADS ACROSS FA TUESDAY AS REGION TRANSITIONS INTO MID LEVEL NW FLOW. REMAINDER OF PERIOD LOOKS RELATIVELY QUIET WITH SURFACE HIGH PRESSURE AND MID LEVEL NW FLOW. BASED ON THERMAL PROFILE MAX TEMPERATURES SHOULD BE AT OR A LITTLE SHY OF AVERAGE WITH COOL NIGHTS. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ TG/VOELKER nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 215 PM EDT SUN AUG 3 2008 ...NEAR CLIMO RAIN CHANCES AND WARMER THAN NORMAL TEMPS THIS WEEK... .SHORT TERM...MSAS ANALYSIS REVEALS PRESSURE CENTERS ABOUND ACROSS THE SOUTHEAST BUT ALL ARE LOCATED OUTSIDE OF OUR AREA. THE FIRST IS A RIDGE OF HIGH PRESSURE OVER SOUTH CENTRAL FLORIDA WHICH CONTINUES TO PROMOTE A SOUTHWEST FLOW REGIME FOR THE FORECAST AREA. THE SECOND IS THE DEVELOPING LOW PRESSURE AREA OVER THE NORTHEAST GULF WHICH IS SLOWLY MAKING ITS WAY INTO THE NORTH- CENTRAL GULF. THE INFLUENCE OF THE LOW CONTINUES TO DWINDLE OVER WESTERN SECTIONS OF THE FORECAST AREA WHERE LESS GUSTINESS TO THE WIND FLOW HAS BEEN REPORTED TODAY COMPARED TO YESTERDAY. FINALLY...A VERY WEAK TROUGH OF LOW PRESSURE EXTENDS FROM SOUTHERN ALABAMA THROUGH SOUTH CENTRAL GA AND THE LOWLANDS OF SOUTH CAROLINA. ACTIVITY ALONG THIS BOUNDARY FIRED UP LATE LAST NIGHT AND THIS SHOULD ACTUALLY POSE THE GREATEST INFLUENCE OVER OUR REGION LATER THIS EVENING. EXPECT UPSTREAM BOUNDARY TO REMAIN NORTH OF THE AREA BUT DEVELOPMENT ALONG IT LOOKS LIKELY DURING THE EVENING HOURS. STEERING FLOW TO THE SOUTHEAST IS PRESENT FOR ONLY THE NORTHERN 3 TO 5 COUNTIES IN MY GA ZONES AND EXPECT THIS AREA TO HAVE THE GREATEST CHANCE OF THUNDERSTORMS ADVECTING IN. THAT SAID...PROBABILITIES WILL REMAIN LOW WITH ONLY LOW END SCATTERED PRESENTLY ADVERTISED IN THE GRIDS. SPC HAS OUTLINED THIS AREA IN SLIGHT RISK WITH LATEST RUC SOUNDINGS SHOWING CAPE INCREASING TO OVER 3500 J/KG...LI`S OF -9C AND DELTA THETA E DIFFERENCES OVER 30 C. LAPSE RATES REMAIN MARGINAL BUT GOOD PARTICLE SEPARATION SHOULD LEAD TO THE THREAT OF HAIL ALONG WITH THE DOWNBURST POTENTIAL. TROUGH BECOMES MORE DIFFUSE ON TUESDAY AND WEDNESDAY AND FOCUS SHIFTS TO THE SOUTH WHERE DEEPER MOISTURE WILL TRY TO INCREASE. DEVELOPING EASTERLY STEERING FLOW WILL RESULT IN HIGHEST POP CHANCES ALONG THE INTERSTATE 75 CORRIDOR AND MOISTURE PROFILES WARRANT HIGH POPS OVER THE FLORIDA PORTION THROUGH WED EVENING. UPPER RIDGE BUILDING OVER THE AREA AND A LACK OF CLOUD COVER THROUGH EARLY AFTERNOON WILL RESULT IN TEMPS IN THE MID 90S OVER INLAND PORTIONS. .LONG TERM...PERSISTENT EAST COAST UPPER TROUGH BUILDS IN AGAIN BY WEEKS END WITH A RETURN TO A SOUTHWEST FLOW REGIME AND DEEPER MOISTURE MOVING INTO THE AREA. CURRENT GRID SET HAS A GOOD HANDLE ON THIS AND NO CHANGES ARE PLANNED. && .AVIATION...LOW THUNDERSTORMS CHANCES OF ABOUT 20% OR LESS SO HAVE CONTINUED WITH VCTS OR CB IN THE FORECAST INTO THIS EVENING. FOR TONIGHT...ONLY LIGHT PATCHES OF FOG POSSIBLE TONIGHT AND ONLY 1 SITE HAD FOG THIS MORNING. BASED ON MODEL SOUNDINGS...HAVE LEFT CONDS AT VFR INTO EARLY MON MORNING. BETTER RAIN CHANCES ARE IN STORE FOR MONDAY BUT BEST CHANCES ARE IN THE AFTERNOON AND ONLY HAVE MENTION OF CBS FOR THE AFTERNOON TIME FRAME AT THIS TIME. && .MARINE...WINDS ARE SE TO SW OVER THE MARINE ZONES AT 12 KT OR LESS. SEAS CONTINUE LOW AT 3 FT OR LESS. MODELS ARE IN REASONABLY GOOD AGREEMENT ON WIND SPEEDS ROUGHLY 15-20 KT OFFSHORE WATERS AGAIN TONIGHT SO WILL PROBABLY GO THAT ROUTE WITH SCEC HEADLINE AT LEAST IN THE 00Z-06Z TIME FRAME. THEREAFTER WINDS APPEAR TO DROP DOWN TO 10-15 KT TOWARD SUNRISE. THE SFC RIDGE AXIS MAY BUILD SLOWLY NWD INTO TUE THEN DRIFT BACK S WED AND THU. THUS GENERAL PATTERN OF S TO SW WINDS AROUND 15 KT OR LESS EXPECTED FOR THE FORECAST AND SEAS GENERALLY RUNNING AT 2-3 FT...WITH A SLIGHT INCREASE IN OFFSHORE FLOW AGAIN BY LATE WED INTO THU. && .PRELIMINARY POINT TEMPS/POPS... AMG 75 95 74 96 / 20 20 10 30 SSI 78 90 77 90 / 20 30 20 20 JAX 77 93 77 92 / 20 30 20 30 SGJ 76 90 76 90 / 20 30 30 30 GNV 74 92 74 94 / 20 40 30 40 OCF 72 91 72 93 / 20 40 20 50 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...NONE. GA...NONE. AM...NONE. && $$ DEESE/SHASHY/KERNS fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 321 PM CDT SUN AUG 3 2008 .DISCUSSION... THE FORECAST CONCERNS CENTER AROUND SEVERE WEATHER POTENTIAL THIS EVENING. ELEVATED CONVECTION HAS DEVELOPED AT NOSE OF 850-600MB THETA-E ADVECTION AHEAD OF MID-LEVEL SHORTWAVE ACROSS CTRL MN INTO WRN WI. THESE STORMS CONTINUE TO EVOLVE EASTWARD AT EDGE OF MID-LEVEL CAP. THIS SHOULD CONTINUE THROUGH THE LATE AFTN AND POSSIBILITY INTO THE EVE WITH STEEP MID-LEVEL LAPSE RATES AND ASSOCIATED MUCAPES OF 2000-4000 J/KG. LARGE CAPE INDICATED ALSO IN THE MAIN HAIL GROWTH REGION. ELEVATED SUPERCELLS HAVE TAKEN OVER AS PRIMARY MODE AND EXPECT THAT TO CONTINUE LOOKING AT OBSERVATIONAL DATA /VAD PROFILER/ AND MESOANALYSIS DATA. HAIL THE MOST LIKELY THREAT WITH THESE THROUGH THE DAYLIGHT HOURS. CONCERN FOR BOUNDARY LAYER BASED CONVECTION IS GROWING IN SOUTH CTRL MN...WITH INITIATION BETWEEN 5 PM AND 8 PM APPEARING LIKELY. 1005MB SFC LOW HAS EVOLVED INTO FAR SE SD DURING THE MIDDLE OF THIS AFTN...WITH ASSOCIATED SFC WARM FRONT DRAPED NEAR OR JUST NORTH OF I-90. THIS HAS BEEN DIABATICALLY ENHANCED DUE TO CLOUD COVER TO THE NORTH AND BAKING HEAT TO THE SOUTH. CUMULUS CLOUD STREETS /POSSIBLY HORIZONTAL CONVECTIVE ROLLS/ HAVE SHOWN UP IN ERN TO NERN IA AND ARE ADVECTING INTO SOUTH CTRL MN. STILL A GREAT AMOUNT OF SURFACE BASED AND MIXED-LAYER CIN IN THAT AREA AS INDICATED BY DIAGNOSTIC SOUNDINGS...ALONG WITH THE BASIC H7 TEMPS A WARM 15C. BUT...SHORTWAVE OR VORT MAXIMA EXTENSION FROM AFOREMENTIONED WAVE IN CTRL MN IS PRESENT ON SATELLITE CHANNELS IN SOUTH CTRL SD. ASSOCIATED HEIGHT FALLS AHEAD OF THIS INDICATED ON THE RUC MODEL COMING ACROSS INTO ERN SD AND SOON INTO SRN MN. SHORT RANGE HIGH RESOLUTION MODELS INDICATE THIS IS ENOUGH TO TRIGGER CONVECTION IN SRN MN. CONVECTIVE TEMPS FOR TRIGGERING SFC BASED CONVECTION WILL BE CLOSE TO BEING REACHED...WITH ADAPTED FORECAST SOUNDINGS FOR DEW POINTS IN THE 75-77F BALLPARK INDICATING CONVECTIVE TEMPS TO NEAR 90F NEEDED FROM FAIRMONT UP TO MANKATO. DEEP LAYER SHEAR OF 40-50 KTS DUE TO INCREASING MID-LEVEL FLOW WITH ASSOCIATED SHORTWAVE IS PLENTY SUFFICIENT FOR SUPERCELLS. 0-1KM SHEAR PREDICTED BY THE RUC AND NAM TO BE BETWEEN 20-30 KTS...HELPED IN PART BY THE RE-INCREASING LLJ. BACKED LOW LEVEL FLOW IN OUR SOUTH CTRL COUNTIES ALSO AIDING POTENTIAL FOR TORNADOES. IT WOULD SEEM LIKE THE GREATEST CHANCE FOR TORNADOES WOULD BE SOON AFTER INITIATION. SIG TOR POTENTIAL SEEMS BRIEF BUT POSSIBLE ACCORDING TO SREF PROBABILITIES ALONG WITH LOCAL RESEARCH REGRESSIONS FOR FAVORABLE SIG TOR PARAMETERS. DOWNBURST POTENTIAL AND LARGE HAIL SEEM VERY LIKELY WITH CELLS DUE TO THE STRONG CAPE AND DCAPE AVAILABLE TO WORK WITH IN THAT AREA. MOST LIKELY TIMING FOR BOUNDARY-LAYER BASED SUPERCELLS WOULD BE 5 PM TO 10 PM. HAVE SVR MENTIONED IN THE FORECAST GRIDS DURING THAT TIME. AS LLJ INTENSIFIES AND FOCUSES INTO SE MN AND WRN WI AHEAD OF SHORT WAVE THIS EVE...CONVECTION SHOULD INCREASE IN AREAL COVERAGE...INCLUDING IN ERN MN AND WRN WI. THIS SHOULD BE ELEVATED IN ERN MN AND WRN WI...WITH STEEP MID-LEVEL LAPSE RATES CONTINUING TO FEED THE CONVECTION. EVENTUAL ORGANIZATION SEEMS LIKELY...GIVEN FAVORABLE MCS/DERECHO PARAMETERS...THAT WOULD ESPECIALLY TAKE OFF OVER SE MN INTO SRN WI LATE THIS EVE INTO OVERNIGHT. SO HAVE HIGHEST POPS THIS EVE AND THEN BEGIN SLOWLY TAILORING BACK...ESPECIALLY IN THE WEST AS SFC COLD FRONT/TROUGH EXTENDING NWRD FROM THE SFC LOW WORK EASTWARD INTO THE FORECAST AREA. THE LIGHT LOW LEVEL WIND FLOW ALONG WITH NO STRONG DRY AIR ADVECTION SHOULD LEAD TO FOG/STRATUS DEVELOPMENT ACROSS MUCH OF THE MN CWA AND POSSIBLY THE WI CWA BY VERY LATE TONIGHT. FOR MON...EVERYTHING EVOLVES SLIGHTLY SOUTHWARD INCLUDING THE UPPER LEVEL JET AND COOLER MID-LEVEL TEMPS. THIS WILL HELP TO AID CONVECTION...POSSIBLY SEVERE DURING THE AFTN AND EVE ON MON. THE MAIN SFC BOUNDARY SHOULD BE TOO OUR SOUTH...HELPED IN PART BY THE CONVECTION TONIGHT. DRY AIR ADVECTION BEGINS TO OOZE INTO THE REGION BY LATE MON NIGHT INTO TUES. REALLY LOOKS LIKE A PLEASANT WEEK AFTER THAT POINT AS ERN NA LONG WAVE TROUGH RE-ESTABLISHES ITSELF. POCKETS OF VORT MAXIMA SEEN ON THE WEST SIDE OF THIS MAY LEAD TO SMALL CHANCES FOR SHOWERS BUT THIS CONTINUES TO FAVOR THE CTRL GREAT LAKES REGION MORE. HAVE BUMPED DOWN MIN TEMPS FOR FRI INTO NEXT WEEKEND...CLOSER TO LOWER VALUES OF 00Z MEN GUIDANCE BASED ON 850MB TEMPS CREEPING INTO THE SINGLE DIGITS INTO CTRL MN AND WRN WI. && .AVIATION... /18Z TAF ISSUANCE/ SMALL THUNDERSTORM COMPLEX BETWEEN THE NORTHERN SUBURBS OF THE TWIN CITIES AND DULUTH MOVING ENE. ACTIVITY IS ALONG A SHORT WAVE TRACKING ACROSS EASTERN MN. 700 MB TEMPERATURES ABOVE 14 DEG C TO THE SSW OF THE TWIN CITIES HELPING TO CAP ANY DEVELOPMENT IN THAT DIRECTION FOR THE TIME BEING. MORE RIPPLES IN THE UPPER FLOW ACROSS THE DAKOTAS. ACTIVITY OVER THE EASTERN DAKOTAS IS ALONG A SURFACE FRONT AND ANOTHER SHORT WAVE ALOFT. THE FRONT AND ACTIVITY WILL SPREAD INTO WESTERN MN THIS AFTERNOON AND INTO EASTERN MN AND WEST CENTRAL WI EARLY TONIGHT. HAVE INDICATED SOME TEMPO GROUPS TO TRY AND TIME THE BEST CHANCES FOR THUNDER. THE FRONT WILL BE OVER THE EASTERN AND SOUTHERN CWA MONDAY MORNING. A VERY BAGGY PRESSURE PATTERN AND DEW POINTS IN THE MIDDLE 60S TO LOWER 70S STILL EXPECTED FROM KSTC AND KRWF ON EASTWARD. NAM BUFKIT HYDROLAPSE INCREASING FROM 4 G/KG BETWEEN THE SURFACE AND 500 FEET EARLY MONDAY MORNING. HENCE...THERE IS PRETTY HIGH POTENTIAL FOR STATUS AND FOG. EXPECT VISIBILITIES IN THE 1 TO 3 MILE RANGE WITH CEILING BETWEEN 500 AND 1500 FEET. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ MTF/RAH mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBUQUERQUE NM 305 PM MDT SUN AUG 3 2008 .DISCUSSION... 20Z SURFACE ANALYSIS SHOWS A 1000MB LOW PRES CENTER OVER SE CO WITH A SURFACE TROUGH EXTENDING SW ACROSS THE NORTHERN MTNS DOWN INTO THE GILA WILDERNESS. CONVECTION IS FIRING ALONG THIS SFC BOUNDARY TODAY AND MOVING VERY LITTLE. LATEST WATER VAPOR LOOP SHOWS A NICE SHORTWAVE OVER SOUTHERN NM/NORTHERN CHIHUAHUA MOVING SLOWLY NORTH. ALL OF THIS COMBINED WITH PWATS NEAR 1 INCH HAS ALLOWED FOR LOCALLY HEAVY RAIN WITH A FEW FLOOD ADVISORIES ALREADY POSTED ACROSS THE REGION. FOR TONIGHT AND MONDAY...RAISED POPS TO LIKELY OVER THE NORTHERN/ WEST CENTRAL MTNS IN LINE WITH 12Z WRF/15Z SREF/18Z RUC13. MOST CONVECTION WILL FADE BY 03Z...BUT THINKING OUTFLOW BOUNDARIES COULD KEEP A FEW CELLS GOING THEREAFTER. MODEL PWATS REALLY RAMP UP MONDAY WITH WIDESPREAD 1 TO 1.4 INCH VALUES FROM THE CENTRAL MTNS WEST. 12Z NAM INDICATES THE CURRENT UPPER WAVE AND SFC TROUGH WILL BECOME ORIENTED SW-NE MONDAY INTO MONDAY EVENING FROM THE GILA TO AROUND ABQ...SANTA FE AND RATON. RAISED POPS TO HIGH CHANCE/LIKELY IN THIS AREA AS WELL...WITH LOCALLY HEAVY RAINFALL POSSIBLE. HIGH PWATS REMAIN IN PLACE TUESDAY AND TUESDAY NIGHT WITH THE AXIS OF BEST MOISTURE CONVERGENCE SLIDING SLOWLY NORTHWEST INTO THE NORTHWEST CORNER OF THE STATE THROUGH WEDNESDAY. RAISED POPS TO LIKELY AGAIN OVER THE NORTHERN MTNS IN THIS PATTERN AS DAILY ROUNDS OF CONVECTION WILL OCCUR IN THESE AREAS. STORM MOTIONS TUESDAY ARE EXPECTED TO BE A LITTLE FASTER THAN MONDAY AND ACT TO THE NORTH AND NORTHWEST. STORM MOTIONS BECOME ERRATIC/SLOW AGAIN WEDNESDAY WITH THE POTENTIAL FOR LOCALLY HEAVY RAINFALL CONTINUING. THE FUTURE OF THE TROPICAL DISTURBANCE OVER THE NORTH CENTRAL GULF OF MEXICO IS STILL IN QUESTION FOR LATER THIS WEEK. MODELS SHOW THE CENTER OF CIRCULATION VERY CLOSE TO THE COAST BECOMING WASHED OUT OVER TEXAS BY MIDWEEK. ANY MOISTURE ASSCD WITH THIS SYSTEM COULD BE INGESTED INTO THE MONSOONAL CIRCULATION...ALLOWING FOR ENHANCED STORM ACTIVITY OVER THE STATE INTO THE WEEKEND. GUYER && .AVIATION... ISOLATED TO SCATTERED THUNDERSTORMS WILL CONTINUE OVER THE WESTERN TWO THIRDS OF THE STATE THROUGH THIS EVENING...BUT OVERALL INTENSITY AND COVERAGE SHOULD DIMINISH AFTER 00Z. LOCALIZED MVFR CIGS AND VSBYS ARE POSSIBLE IN THE STRONGEST STORMS ALONG WITH WIND GUSTS TO 35 KNOTS. LINGERING SHOWERS AND ISOLATED MVFR CIGS MAY OCCUR OVERNIGHT WEST OF I 25 AND SOUTH OF I 40. NEXT AVIATION DISCUSSION SCHEDULED FOR 09Z...KD && .FIRE WEATHER... A GENERAL INCREASE IN MOISTURE FROM SOUTHERLY FLOW AT LOW TO MID LEVELS OF THE ATMOSPHERE WILL CONTINUE THROUGH THE WEEK. THIS WILL RESULT IN HIGHER HUMIDITIES ON AVERAGE WITH AN UPSWING IN STORMS CAPABLE OF PRODUCING WETTING RAINS ACROSS PRIMARILY THE NORTHWEST TWO THIRDS OF THE AREA. THE LOWEST AFTERNOON HUMIDITIES EARLY IN THE WEEK WILL BE IN THE SOUTHEAST AND FAR NORTHWEST. KD && .PRELIMINARY POINT TEMPS/POPS... FARMINGTON...................... 65 95 66 93 / 10 20 20 20 GALLUP.......................... 57 87 57 86 / 30 20 40 30 GRANTS.......................... 52 86 55 86 / 40 20 40 30 GLENWOOD........................ 59 86 60 86 / 50 40 50 30 CHAMA........................... 47 82 49 80 / 50 30 30 40 LOS ALAMOS...................... 62 82 60 81 / 40 30 40 40 RED RIVER....................... 48 78 48 72 / 50 40 40 50 TAOS............................ 54 88 53 83 / 40 20 30 40 SANTA FE........................ 58 87 57 86 / 40 30 40 40 SANTA FE AIRPORT................ 60 90 60 89 / 40 20 40 40 ESPANOLA........................ 59 92 59 91 / 40 20 20 30 ALBUQUERQUE HEIGHTS............. 69 91 69 91 / 30 20 30 40 ALBUQUERQUE VALLEY.............. 67 93 67 92 / 30 20 30 30 ALBUQUERQUE FOOTHILLS........... 65 88 64 87 / 30 30 40 40 ALBUQUERQUE WEST MESA........... 67 92 65 92 / 30 20 40 30 SOCORRO......................... 68 95 65 94 / 20 20 40 20 SANDIA PARK/CEDAR CREST......... 57 80 55 80 / 40 40 50 50 MORIARTY/ESTANCIA............... 58 84 56 82 / 40 20 40 30 CARRIZOZO....................... 62 87 62 87 / 20 20 30 10 RUIDOSO......................... 55 79 55 79 / 20 50 50 20 RATON........................... 57 91 56 85 / 20 20 30 30 LAS VEGAS....................... 57 86 55 83 / 20 20 30 20 ROY............................. 63 94 61 90 / 10 20 20 10 CLAYTON......................... 66 96 65 94 / 5 10 10 10 SANTA ROSA...................... 65 96 63 95 / 5 10 20 10 TUCUMCARI....................... 68 99 68 98 / 5 5 5 5 FORT SUMNER..................... 65 95 65 95 / 5 5 5 5 CLOVIS.......................... 66 95 66 95 / 5 0 0 0 PORTALES........................ 67 96 66 96 / 5 0 0 0 ROSWELL......................... 69 97 69 97 / 10 0 0 0 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$ GUYER/19 nm AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 308 PM CDT SUN AUG 3 2008 .SHORT TERM...CHALLENGES WILL BE CONVECTIVE/SEVERE CHANCES THIS AFTERNOON/EVENING...PRECIP CHANCES MONDAY...AND TEMPERATURES. 12Z MODELS INITIALIZED DECENT AND IN OVERALL AGREEMENT...WILL USE BLEND FOR DETAILS. ZONAL/SW FLOW ALOFT WILL TRANSITION TO NW BY TUESDAY AS UPPER LOW ACROSS CENTRAL CANADA PROPAGATES EASTWARD. WILL KEEP AT LEAST 20 POPS FOR MUCH OF THE AREA THROUGH MON NIGHT GIVEN SW/ZONAL FLOW SINCE NOTHING CAN BE RULED OUT. WILL HIGHLIGHT BEST PRECIP CHANCES WITH 30-40 POPS. LATER SHIFTS CAN RAISE POPS IF CONFIDENCE INCREASES. THIS AFTERNOON INTO TONIGHT...MAIN SFC LOW/WARM FRONT WELL SOUTH OF THE FA (SE SD INTO S MN) AND NOT EXPECTED TO MOVE MUCH FURTHER NORTH. STRONG 850MB WARM AIR ADVECTION AND 850MB JET FOCUSED JUST SE OF THE FA IN CENTRAL MN TO N WI. THIS FORCING EXPECTED TO SLOWLY PROPAGATE EAST. THIS LEAVES INVERTED TROUGH AND ASSOCIATED SFC CONVERGENCE AS LIFTING MECHANISM FOR CONVECTION ACROSS THE FA. THIS FEATURE LOCATED FROM SFC LOW THROUGH SE ND INTO NW MN. BEST MOISTURE FLUX CONVERGENCE LOCATED ALONG THIS TROUGH. THIS FEATURE WILL SLOWLY SAG E/SE. MID-LEVEL LAPSE RATES ARE STEEPEST ACROSS THE S FA AND MLCAPE VALUES ARE APPROACHING 1000-2000 J/KG ACROSS THIS AREA. MUCAPE IS RAPIDLY DECREASING PAST COUPLE HOURS ACROSS THE N FA WITH MLCAPE NIL. THIS LEAVES THE S FA WITH BEST CHANCES FOR CONVECTION AS INVERTED TROUGH GOES THROUGH. RUC DOES SHOW CAP TO WEAKEN ENOUGH ALLOWING CONVECTIVE INITIATION. THIS AREA HAS BEEN MOSTLY CLOUD FREE MUCH OF THE AFTERNOON WITH SFC DEW POINT VALUES APPROACHING 70F. WILL GO WITH HIGHEST POPS ACROSS THE S FA. SEVERE POTENTIAL STILL QUESTIONABLE GIVEN HIGH FREEZING LEVELS (AOA 15KFT). DEEP LAYER SHEAR SUFFICIENT (50KNTS) FOR SEVERE...BUT WEAK SFC CONVERGENCE AND LACK OF STRONG FORCING MECHANISM MAY PREVENT WIDESPREAD STRONG STORMS. WILL NOT MENTION SEVERE IN GRIDS AT THIS TIME. HOWEVER...WILL NEED TO MONITOR WATER VAPOR IMAGERY FOR ANY HIDDEN WAVES WHICH MAY GIVE ADDED LIFT. ANY ACTIVITY SHOULD DIMINISH BY MIDNIGHT. MONDAY...SHORTWAVE ENERGY ACROSS NE MONTANA/IDAHO AREA WILL SLOWLY SHIFT EAST AND BRING PRECIP CHANCES TO THE REGION BY MONDAY AFTERNOON. EXACT LOCATION VARIES MODEL TO MODEL AND RUN TO RUN. BEST CHANCES APPEAR TO SHIFT FROM NW HALF OF THE FA TO THE SE HALF OF THE FA MON AFTERNOON/EVENING. TUE-WED...NW FLOW ALOFT AND DRIER AIRMASS SHOULD LEAD TO MOSTLY DRY WX. ONLY CONCERN THIS PERIOD FOR THUNDER WOULD BE WED AS SHORTWAVE ENERGY PASSES JUST NE OF THE FA WITH WEAK INSTABILITY PRESENT. MODELS DIFFER WITH EXACT LOCATION OF THE SHORTWAVE (GFS FURTHER NE AND DRY). PROBABILITIES APPEAR TOO LOW AT THIS POINT TO INSERT POP/WX. .LONG TERM (THU-SUN)...NW FLOW TO NORTHERLY FLOW THROUGH THE PERIOD WILL PUSH ALL DEEP MOISTURE SOUTH AND ALLOW FOR SUBSIDENCE AND HIGH PRESSURE TO DOMINATE THE PERIOD. MODELS IN GOOD AGREEMENT WITH THESE FEATURES...SOMETHING TO WATCH WILL BE 500MB WAVE AT THE END OF PERIOD ROTATING SOUTHWARD FROM HUDSON BAY LOW INTO THE REGION ON SUNDAY. KEPT POPS OUT OF THIS ISSUANCE BUT IF FEATURE IS THERE ON FUTURE RUNS WILL WANT TO INTRODUCE SOME POPS IN SUBSEQUENT FORECASTS. WITH THICKNESSES ON THE WAY DOWN TEMPS WILL BE COOLER THAN FIRST WEEK OF AUGUST NORMALS. && .AVIATION...THUNDERSTORM CHANCES THIS EVENING WITH UNCERTAINTY AS TO EXACT LOCATION SO INCLUDED CB IN ALL TAF SITES EXCEPT DVL WHERE STRATUS DECK HAS HELD STEADY MOST OF THE DAY. STRATUS DECK IS EXPANDING EAST AND SOUTH WILL INCLUDE GFK AND TVF FOR PORTIONS OF THE AFTERNOON. OTHERWISE EXPECT VFR CONDITIONS FOR THE OVERNIGHT ACROSS THE ENTIRE AREA. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ TG/JK nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 1143 AM CDT SUN AUG 3 2008 .UPDATE...FORECAST IS WELL ON TRACK FOR MOST ELEMENTS. MADE SOME TWEAKS TO DEWPOINT/HUMIDITY IN THE AFTERNOON GRIDS...KEEPING DEWPOINTS A LITTLE CLOSER TO 60 DEGREES IN THE I-35 CORRIDOR BASED ON MORNING SOUNDINGS AND SUPPORT FROM THE NAM. THE RUC APPEARED TOO AGRESSIVE IN MIXING DEWPOINTS DOWN TO THE 40S AND LOW 50S REGIONWIDE. CHANGES WERE NOT SIGNIFICANT ENOUGH TO WARRANT A ZONE UPDATE. MAIN FORECAST CHALLENGE IS WHAT TO DO WITH THE HEAT ADVISORY BEYOND ITS CURRENT MONDAY AFTERNOON EXPIRATION TIME. WEST/NORTHWEST COUNTIES WILL LIKELY REMAIN VEERED AND DRY THROUGH TUESDAY. EXPECT INCREASING DEWPOINTS FARTHER SOUTH/EAST UNDER WEAK INFLUENCE FROM A WESTWARD MOVING TROUGH ALONG THE GULF COAST. HOW MUCH THIS WILL INFLUENCE TEMPERATURES AND HEAT INDICES WILL DETERMINE THE NEED TO EXTEND AND/OR REORIENT THE HEAT ADVISORY. && BURKE && .PREV DISCUSSION... /ISSUED 437 AM CDT SUN AUG 3 2008/ DISCUSSION... BROAD UPPER LEVEL RIDGE HAS ESTABLISHED ITSELF OVER THE SOUTHERN PLAINS. TRIPLE DIGIT HIGH TEMPS REPORTED OVER BASICALLY THE ENTIRE CWA YESTERDAY AFTERNOON. LITTLE CHANGE IN CONDITIONS FROM YESTERDAY...OTHER THAN AFTERNOON DEW POINTS FALLING INTO THE 50S OVER MOST OF THE AREA. A SUBSTANTIAL EASTERLY COMPONENT TO WINDS EXPECTED ON TUE...WITH THE RETURN OF LOWER LEVEL MOISTURE. EASTERLY WAVE MOVING ONTO TX GULF COAST ON TUE SHOULD HAVE VERY LITTLE EFFECT ON NORTH TX COUNTIES...OTHER THAN THE INCREASE IN MOISTURE. THE EAST WINDS WILL ALSO BRING SLIGHTLY COOLER TEMPS...AND THE COMBINATION OF HEAT AND HUMIDITY WILL RESULT IN HEAT INDICES AROUND 105 ONCE AGAIN. PLAN ON KEEPING HEAT ADVISORY VALID UNTIL MON PM FOR NOW...WITH THE IDEA THAT IT MAY NEED TO BE EXTENDED THROUGH TUE. MED RANGE MODELS ALL HINT AT RIDGE WEAKENING SOMEWHAT BY WED/THU. GFS BRINGS WEAK COLD FRONT ALL THE WAY THROUGH OK BY THU EVENING...THOUGH AM SOMEWHAT SKEPTICAL ABOUT THIS SCENARIO IN EARLY AUGUST. AT ANY RATE...IT SEEMS QUITE POSSIBLE THAT NWLY FLOW COULD DEVELOP LATE THIS WEEK...WITH A CHANCE OF TSTM CLUSTERS RESULTING FROM DIURNAL CONVECTION ON THE HIGH PLAINS MOVING THROUGH THE AREA. INCLUDED SLIGHT CHANCE POPS NEAR KS BORDER ON WED AS FRONTAL BOUNDARY APPROACHES N OK...WITH SLIGHT CHANCE FOR RAIN FROM PM FRI ONWARD THROUGH MUCH OF THE CWA IN ANTICIPATION OF SE MOVING TSTM CLUSTERS. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 105 75 104 76 / 0 0 0 10 HOBART OK 107 76 107 77 / 0 0 0 0 WICHITA FALLS TX 108 77 107 77 / 0 0 0 0 GAGE OK 104 71 106 70 / 0 0 0 10 PONCA CITY OK 102 77 102 78 / 0 0 0 10 DURANT OK 104 73 100 74 / 0 0 0 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...HEAT ADVISORY UNTIL 6 PM CDT MONDAY FOR OKZ005>008-010>013- 015>020-022>032-035-037>048-050>052. TX...HEAT ADVISORY UNTIL 6 PM CDT MONDAY FOR TXZ085-086-088>090. && $$ 25/03 ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 212 PM CDT SUN AUG 3 2008 .SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT ACTIVE WEATHER EXPECTED IN THE NEAR TERM AS UPPER RIDGE IS FLATTENED BY SHORT WAVE ENERGY EJECTING OUT OF CANADIAN UPPER TROUGH. FORECAST CHALLENGE REMAINS THUNDERSTORM AND ASSOCIATED SEVERE WEATHER THREATS TONIGHT AND AGAIN TOMORROW. FORECAST AREA UNDER THE TRANSITION ZONE TODAY WITH STRONG WARM AIR AND MOISTURE ADVECTION PUSHING IN FROM THE SOUTHWEST. ELEVATED WARM LAYER HAS BEEN TRIGGERING THUNDERSTORMS ACROSS CENTRAL MINNESOTA INTO NORTHWEST WISCONSIN BUT MAIN PUSH IS TO THE NORTHEAST AND WITH DRIER AND FAR MORE STABLE AIRMASS IN PLACE ACROSS THE REST OF WISCONSIN...STORMS HAVING HARD TIMES STAYING ORGANIZED. MEANWHILE SURFACE WARM FRONT EXTENDS FROM LOW OVER SOUTHEAST SOUTH DAKOTA INTO CENTRAL IOWA. AHEAD OF THIS FRONT TEMPERATURES HAVE BEEN QUITE COOL BUT LOW LEVEL MOISTURE IS MAKING SOME PROGRESS WITH DEW POINTS SLOWLY RISING. EVENING WEATHER COULD BE QUITE INTERESTING. THREAT FOR STORMS WILL BATTLE WARM MID LAYER TEMPERATURES BUT PLENTY OF OTHER FACTORS IN PLACE FOR POSSIBLE ORGANIZED SEVERE WEATHER EVENT. GIVEN LOCATION OF SURFACE LOW AND WARM FRONT...COULD SEE THUNDERSTORMS ERUPT ALONG AND JUST NORTH OF BOUNDARY THIS EVENING. RUC MODEL HAS BEEN HINTING AT SURGE OF RICH 850 MB THETA-E AIR ALONG WARM FRONT AS WELL AND THIS MATCHES OTHER SHORT TERM GUIDANCE IN DEVELOPING STORMS IN SAME REGION EARLY THIS EVENING. 40 KNOTS OF DEEP LAYER SHEAR AMPLE ENOUGH TO SUSTAIN SUPERCELLS AND FAVORABLE LOW LEVEL SHEAR MAY EVEN ENHANCE LOCAL TORNADO THREAT. THIS WILL HAVE TO BE WATCHED CLOSELY. STORMS WOULD THEN MOVE INTO NORTHEAST IOWA AND SOUTHEAST MINNESOTA... PERHAPS BECOMING MORE ELEVATED AS THEY TRACK EAST INTO WISCONSIN TOWARDS THE OVERNIGHT. EITHER WAY...HAVE RAISED POPS TONIGHT FOR THIS SCENARIO. BOUNDARY WILL REMAIN NEARBY ON MONDAY AS UPPER TROUGH BECOMES MORE ESTABLISHED AND ZONAL FLOW BEGINS TO BECOME A BIT MORE NORTHWESTERLY. MID LEVEL WINDS WILL BE ON THE INCREASE AS NORTHERN SYSTEM BECOMES MORE DOMINANT WEATHER MAKER. OUTCOME STILL REMAINS A BIT TRICKY BUT BANKING ON A ROUND OR TWO OF CONVECTION GOING MONDAY MORNING...WITH ANOTHER POSSIBLE ORGANIZED SEVERE WEATHER EPISODE LATER IN THE DAY TRIGGERED BY ANOTHER SHORT WAVE IMPULSE. AT LEAST PARTS OF FORECAST AREA WILL BE INTO THE WARM SECTOR AS WELL. TEMPERATURE FORECASTS WILL ALSO BE TOUGH AND COULD VARY QUITE A BIT FROM NORTH TO SOUTH AND IN AREAS THAT CLEAR OUT. BY TUESDAY SURFACE LOW AND FRONTAL BOUNDARIES SHOULD BE FURTHER SOUTH AS COOLER AIR STARTS TO PUSH IN. COULD BE SOME LINGERING RAIN THREATS BUT BULK OF SEVERE WEATHER THREAT SHOULD BE OFF TO THE SOUTH AND EAST BY THEN. .LONG TERM...THURSDAY THROUGH SUNDAY AMPLIFICATION IN UPPER PATTERN WILL PUT WESTERN GREAT LAKES INTO NORTHWEST FLOW AS ANOMOLOUS UPPER TROUGH SETTLES INTO EASTERN U.S. IN LATER PERIODS. THIS WILL MAKE FOR QUIETER WEATHER...WITH COOLER AND DRIER REGIME DROPPING TEMPERATURES BACK UNDER NORMALS FOR EARLY AUGUST. DRY FORECAST RUNNING EXCEPT FOR TWO PERIODS. SIGNAL STILL THERE IN MEDIUM RANGE GUIDANCE FOR WEAK SHORT WAVE TO PASS THROUGH THE GREAT LAKES ON THURSDAY AND COULD HELP GENERATE SOME DIURNAL INSTABILITY SHOWERS OR STORMS ACROSS CENTRAL WISCONSIN. OTHER THREAT IS ON SUNDAY /DAY 7/ SINCE GUIDANCE IS NOW HINTING AT MORE SIGNIFICANT IMPULSE DROPPING INTO WESTERN GREAT LAKES ON BACK SIDE OF UPPER TROUGH. AGAIN...THIS COULD GENERATE ROUND OF CONVECTION AS IT PASSES AS EARLY AS SATURDAY NIGHT BUT TOO FAR OUT FOR DETAILS. && .AVIATION... THUNDERSTORM POTENTIAL CONTINUES TO BE THE FOCUS IN THE TAFS. WARM AIR IN MID LEVELS BUILDING NORTHEASTWARD TODAY...THUS CAPPING THE ATMOSPHERE FROM CONVECTIVE INITIATION. ACCORDING TO THE LATEST OPERATIONAL AND PROBABILISTIC DATA...STORMS SHOULD DEVELOP ALONG PERIPHERY OF THE CAP DURING AFTERNOON AND EVENING. CONFIDENCE WAS HIGH ENOUGH TO INCLUDE A PERIOD OF THUNDERSTORMS AT BOTH TAF SITES TONIGHT. SEVERE STORMS WILL BE POSSIBLE...ALTHOUGH AT THIS TIME PREFER TO ALLOW SUBSEQUENT TAF ISSUANCES TO ADDRESS DETAILS OF SEVERE POTENTIAL. IN ADDITION...MVFR CONDITIONS ANTICIPATED FROM ABOUT 04.09Z-04.18Z BASED ON MOISTURE LADEN BOUNDARY LAYER DURING THIS TIME FRAME. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT/LONG TERM...SHEA AVIATION..........THOMPSON wi