AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PHOENIX AZ 1205 PM MST TUE JUL 22 2008 SOUTH-CENTRAL AND SOUTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA FORECAST DISCUSSION .UPDATE...UPDATED AVIATION DISCUSSION. && .SYNOPSIS... DRIER AIR FROM THE WEST MEANS MOSTLY SUNNY SKIES IN SOUTHEAST CALIFORNIA TO THE LOWER COLORADO RIVER VALLEY...AND JUST A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS EAST OF THERE TO ABOUT PHOENIX TODAY. PLENTY OF MOISTURE REMAINS FOR SCATTERED SHOWERS AND THUNDERSTORMS MAINLY NORTH AND EAST OF THE PHOENIX AREA THROUGH THIS AFTERNOON INTO THIS EVENING. A LOW PRESSURE SYSTEM FROM THE EAST WILL BRING A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS SPREADING FROM THE HIGHER TERRAIN EAST OF PHOENIX BACK WEST ACROSS THE DESERT AREAS LATE WEDNESDAY THROUGH THURSDAY WITH RELATIVELY COOLER WEATHER. NEAR AVERAGE TEMPERATURES AND THE DAILY THREAT OF MAINLY HIGHER TERRAIN THUNDERSTORMS WILL CONTINUE THE LATTER PART OF THE WEEK. && .DISCUSSION... THERE WERE ISOLATED THUNDERSTORMS DEVELOPING OVER SOUTHERN GILA COUNTY EARLIER THAN USUAL LATE THIS MORNING WITH SUNNY SKIES ACROSS THE REMAINDER OF THE AREA. PLENTY OF MOISTURE WILL CONTINUE IN THIS AREA. THUS...SHOWERS AND THUNDERSTORMS ARE EXPECTED CONTINUE DEVELOPING THERE THROUGH THIS AFTERNOON INTO THIS EVENING. THE ATMOSPHERE IS STILL VERY MOIST AND UNSTABLE. THUS...LOCALLY HEAVY RAIN WILL OCCUR WITH SOME OF THE STORMS AND WILL MOST LIKELY BE ISSUING SOME SMALL STREAM FLOOD ADVISORIES AND POSSIBLY FLASH FLOOD WARNINGS FOR ZONE 24 INCLUDING SOUTHERN GILA COUNTY THIS AFTERNOON AND/OR THIS EVENING. DRIER AIR FROM THE WEST MEANS MOSTLY SUNNY SKIES IN SOUTHEAST CALIFORNIA TO THE LOWER COLORADO RIVER VALLEY...AND JUST A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS EAST OF THERE TO THE GREATER PHOENIX AREA TODAY. DEW POINT TEMPERATURES WERE GENERALLY 5 TO 10 DEGREES LOWER ACROSS SOUTHEAST CALIFORNIA TO SOUTHWEST AND SOUTH-CENTRAL ARIZONA LATE THIS MORNING...AND TEMPERATURES WERE GENERALLY 2 TO 4 DEGREES HIGHER WHICH IS REFLECTED IN THE FORECAST HIGHS FOR TODAY. PREVIOUS DISCUSSION... WATER VAPOR IMAGERY EARLY THIS MORNING CONTINUES TO SHOW SEVERAL NOTEWORTHY FEATURES. THE ANTICYCLONIC FLOW NOW STRETCHES FROM COLORADO SW TO YUMA...WHILE THE INVERTED TROF OF LOW PRESSURE CONTINUES OVER W-CNTRL TX. THIS TIME YESTERDAY WE WERE TALKING ABOUT TWO TROPICAL SYSTEMS TO WATCH OVER THE NEXT SEVERAL DAYS...AND THAT HAS NOW TURNED TO THREE...WITH GENEVIEVE THE LATEST ADDITION (AND SANDWICHED BETWEEN FAUSTO TO THE WEST AND DOLLY TO THE EAST). IN THE SHORT TERM... HOWEVER...WE`LL KEEP OUR ATTENTION ON THE HIGH CENTER TOWARD THE FOUR CORNERS AND THE WEAK INVERTED TROF OVER TEXAS THAT IS STILL PROGGED TO SLOWLY MOVE THROUGH SONORA MEXICO WED/THU. TODAY...WITHIN THE PAST 24 HOURS...TD/S OUT WEST HAVE DROPPED CONSIDERABLY WITH PWATER DOWN AROUND AN INCH AND A QUARTER COMPARED TO JUST UNDER TWO INCHES OVER THE WEEKEND. SOUNDING PROFILE SHOWS A FAIRLY DEEP LIGHT SOUTHWESTERLY FLOW INTO THE AREA...WHICH WOULD OF COURSE EXPLAIN THE DRYING. FOR THE CENTRAL DESERTS...FCST SOUNDINGS FOR THIS AFTERNOON ALL INDICATE THIS DRIER AIR OUT WEST WILL CONTINUE TO MOVE EASTWARD...WITH A PRETTY GOOD CHUNK OF DRYING SEEN IN THE LOWER LEVELS OF THE FCST KPSR RAOB PROFILE. THE NAM TELLS THE DRIEST STORY WITH A MEAN MIXING RATIO DOWN AROUND 8.5 G/KG... COMPARED TO THE MUCH MORE MOIST RUC THAT HANGS ONTO NEARLY 14 G/KG. THE GFS (AND SUBSEQUENT LOCAL GFS BASED WRF MODEL) ARE SOMEWHERE IN BETWEEN THE TWO EXTREMES...WHICH IS WHAT WE`VE SETTLED ON FOR THE FCST. IN ADDITION TO THE DRIER WESTERLY FLOW IN THE LOWER LEVELS...MODELS APPEAR TO BE IN GOOD AGREEMENT WITH THE 700-500MB FLOW TURNING MORE NORTHEASTERLY TODAY. A NELY FLOW IS FAVORABLE FOR BRINGING CONVECTION OVER THE RIM AND HIGHER TERRAIN TO THE NORTH INTO THE LOWER NORTHERN VALLEY FLOORS...BUT WHETHER WE`LL BE ABLE TO FIRE OFF ANY STORMS IN THE DESERTS IS STILL A QUESTION (GIVEN THE DRIER WESTERLY FLOW IN THE LOWEST LEVELS). POPS/FCST REFLECT A PRETTY LOW CHANCE FOR VALLEY SHOWERS/TSTMS TODAY...INCREASING RATHER DRAMATICALLY TOWARD THE NORTHERN AND EASTERN HIGHER TERRAIN WHERE SCATTERED SHOWERS/TSTMS ARE EXPECTED THIS AFTERNOON AND EARLY EVENING. ONCE AGAIN...WITH THE HIGH PWATERS OVER THE ERN CWA...THE MAIN THREAT WITH SHOWERS/THUNDERSTORMS WILL BE LOCALLY HEAVY PRECIP WITH THE POSSIBILITY OF FLOODING. AS FOR TEMPS...WE CAN EXPECT ANOTHER COUPLE DEG OF WARMER TODAY OVER MONDAY...ESPECIALLY WITH THE DRIER AIR IN THE LOWER LEVELS OF THE ATMOSPHERE. WEDNESDAY...AS MENTIONED EARLIER...WE ARE STILL WATCHING THE INVERTED WEST TEXAS TROF OF LOW PRESSURE SLOWLY MAKE ITS WAY WESTWARD. PREVIOUS MODELS (AND FCST THINKING) WERE LEANING HEAVY ON A WET DAY ACROSS MUCH OF THE CWA WED AND WED NIGHT. STILL EXPECTING A BETTER CHANCE FOR ACTIVITY WED OVER TODAY...BUT NOT CONVINCED ITS GOING TO BE AS WIDESPREAD AND PROLONGED AS PREVIOUS MODEL RUNS/FCSTS WERE CALLING. HAVE BACKED OFF SLIGHTLY ON THE POPS OVER THE GREATER PHOENIX AREA...KEEPING THE HIGHER CHANCES TO OUR SOUTH AND EAST...CLOSER TO WHERE THE MAIN DYNAMICS WITH THE TROF WILL SCOOT THROUGH SONORA MEXICO AND SOUTHERN ARIZONA. AND ONCE AGAIN...THE MAIN THREAT WITH SHOWERS AND TSTMS WED/WED NIGHT WILL BE HEAVY RAIN AND LOCAL FLOODING...BUT FCST CONFIDENCE IN TIMING AND LOCATION OF HEAVIEST SHOWERS REMAINS TOO LOW TO CONSIDER A FLASH FLOOD WATCH AT THIS POINT IN TIME. THURSDAY...WE`LL HANG ONTO A LEAST SLIGHT CHANCE POPS BASICALLY ACROSS THE ENTIRE CWA...WITH CONSIDERABLE CLOUDS ACROSS THE VALLEY. TEMPERATES AS A RESULT COULD VERY WELL STRUGGLE TO REACH 100/101 ACROSS THE WARMEST DESERTS LOCALES...AND CURRENT FCST REFLECTS THIS. FRIDAY THROUGH THE WEEKEND...WE COULD BE IN FOR A FAIRLY SIGNIFICANT MOISTURE INCREASE FROM THE EAST/SOUTHEAST AS THE REMNANTS OF DOLLY MAKES ITS WAY OVER THE SIERRA MADRAS AND INTO THE SOUTHWEST DESERTS. SO MUCH UNCERTAINTY REMAINS THIS FAR OUT IN THE FCST THAT ITS BEST TO CONTINUE A LOW/MOD GRADE MONSOON PATTERN FRIDAY THROUGH THE EXTENDED...WITH TEMPS RUNNING A DEG OR SO COOLER THAN AVERAGE FOR THIS TIME OF YEAR. && .AVIATION... SOUTH-CENTRAL ARIZONA...KPHX/KIWA AND SURROUNDING AIRFIELDS... WITH MOISTLY CLEAR SKIES AND PLENTIFUL MOISTURE CONVECTION STARTS UP EARLY TODAY NORTH AND EAST OF THE PHOENIX AREA. ANTICIPATE ISOLATED TO SCATTERED STORMS...TOPS NEAR 45KFT...TO BE AROUND 35 MILES EAST OF KIWA BY 20Z...IN THE HIGHER TERRAIN ABOUT 45 MILES NORTH OF KPHX THROUGHOUT THE AFTERNOON HOURS. STRONG GUSTY OUTFLOW WINDS...UP TO 35 KTS...AND BRIEF HEAVY RAINFALL ARE LIKELY WITH THESE STORMS IF THEY MOVE INTO THE DESERT ELEVATIONS WITH CIGS BRIEFLY LOWERING TO AROUND 7KFT AGL WITH STORMS VICINITY KIWA. ACTIVITY EXPECTED TO PERSIST INTO THE EVENING HOURS UNTIL AROUND 05Z...THEN DIMINISH WITH CLOUD DECK SCT-BRK AROUND 12KFT UNTIL AROUND 08Z WEDNESDAY. SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA...KNYL/KBLH AND KIPL... DRIER AIR HAS MOVED INTO THE AREA AND NO THUNDERSTORM ACTIVITY IS EXPECTED. WINDS WILL GENERALLY REMAIN LIGHT FOLLOWING DIURNAL PATTERNS THROUGH 18Z WEDNESDAY. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... A MUCH DRIER AIRMASS IS EXPECTED TO MOVE INTO SE CA THROUGH WED...WITH MIN RHS DROPPING BELOW 15 PERCENT IN SPOTS. FURTHER EAST...THE THREAT FOR THUNDERSTORMS WILL CONTINUE OVER THE NEXT SEVERAL DAYS...MAINLY ACROSS THE HIGHER TERRAIN OF SOUTH-CENTRAL AZ. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT WEATHER.GOV/PHOENIX DISCUSSION...ELLIS/WANEK AVIATION...MEYERS FIRE WEATHER...HIRSCH az AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TUCSON AZ 857 AM MST MON JUL 21 2008 .SYNOPSIS...HIGH PRESSURE ALOFT WILL MEANDER NEAR THE FOUR CORNERS THIS WEEK. THIS WILL KEEP SOUTHEAST ARIZONA IN AN ACTIVE MONSOON FLOW REGIME...WITH DAY TO DAY FLUCTUATIONS IN AREAL COVERAGE OF SHOWERS AND THUNDERSTORMS. && .DISCUSSION...INTERESTING AND RATHER COMPLICATED DAY ON TAP FOR SE AZ. THE BOUNDARY LAYER HAS RELOADED NICELY AFTER THE COMPLETE WORKOVER WE RECEIVED SAT NIGHT. WHILE WE ARE QUITE WARM ALOFT WITH 500MB TEMPS AT -3.5C...WE HAVE BECOME QUITE UNSTABLE WITH A CONVECTIVE TEMP OF ONLY 90F...A PRECIP WATER STILL NEAR 2 INCHES... AND PLENTY OF SUNSHINE ALREADY. MODIFIED 12Z SOUNDING FOR 94/60 YIELDS A VALLEY CAPE NEAR 2000J/KG WITH A NARROW ASPECT RATIO AND A FREEZING LEVEL UP NEAR 16KFT. THAT WOULD NORMALLY BE A RECIPE FOR PRETTY WIDESPREAD FLASH FLOOD CONCERNS...EXCEPT WE HAVE ALMOST ZERO FLOW OR SHEAR ALL THE WAY UP TO 300MB...AND ABOVE THAT OUR FLOW IS SLIGHTLY CONFLUENT. RECENT SAT LOOPS AND 12Z UPPER AIR PLOTS SHOW THAT THE UPPER HIGH HAS SPLIT IN TWO...WITH THE MAIN CENTER OVER NW CO BUT A SECONDARY ONE OVER SE AZ. RUC AND INCOMING 12Z WRF-NAM SHOW BETTER UPPER LEVEL SPEED DIVERGENCE OVER W PIMA COUNTY AND ALONG THE NM/AZ BORDER...SO THOSE AREAS MAY BE SLIGHTLY FAVORED THAN THE HEART OF OUR CWA. ELSEWHERE...WITH VIRTUALLY NO FLOW...INITIAL THOUGHT IS THAT TSTMS WILL STRUGGLE TO GET OFF THE MOUNTAINS AND WILL BE VERY PULSEY...THUS SHORT-LIVED IN ANY ONE LOCATION. HOWEVER WHERE THEY FORM...THEY WILL DUMP. IF THERE IS ANY CHANCE FOR THE TSTMS TO BECOME MORE ORGANIZED AND CLUSTER/PROPAGATE INTO THE VALLEYS...IT MAY BE LATER THIS EVENING AS THE SECONDARY HIGH CENTER OVER US WEAKENS AND THE INVERTED TROUGH TO OUR E NUDGES CLOSER TO IMPART AT LEAST A LITTLE E OR ENE FLOW. SO WILL LEAVE THOSE POPS ALONE FOR NOW AND SEE HOW THE DAY EVOLVES. FOR THE AFTERNOON PERIOD...THOUGH... WILL RESTRUCTURE GRIDDED POPS AND QPF A BIT TO INCREASE THE MOUNTAINS AND WEST...WHILE DECREASING THE VALLEYS AND HOLDING THE FAR E CWA AS-IS. HWO HANDLES THE SITUATION PERFECTLY...SO WILL LET THAT RIDE...TOO. OTHERWISE FORECAST IS IN EXCELLENT SHAPE WITH ALL THE DETAILS EXPLAINED IN THE PREV DISCUSSION BELOW. && .AVIATION...MID AND HIGH LEVEL CLOUDS ARE ERODING ON SCHEDULE...WITH CU ALREADY STARTING TO DEVELOP OVER THE MOUNTAINS. EXPECT SCATTERED THUNDERSTORMS TO DEVELOP AGAIN TODAY...MAINLY DURING THE AFTERNOON AND EVENING HOURS. CIGS/VSBYS SHOULD BE WITHIN VFR CRITERIA FOR THE MOST PART...BUT NEAR THUNDERSTORMS CONDITIONS COULD EASILY DROP TO IFR CRITERIA RAPIDLY. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS. && .PREV DISCUSSION...BY TUESDAY THE MODELS INDICATE THAT THE RIDGE AXIS SHOULD SHIFT BACK SLIGHTLY TO THE WEST FROM NORTHERN BAJA INTO THE FOUR CORNERS REGION. MEANWHILE...THE INVERTED TROUGH OVER WEST TEXAS WILL BE SLOWLY MAKING ITS WAY TOWARD THE DESERT SOUTHWEST. STEERING FLOW ON TUESDAY SHOULD BE FROM THE NE-E. BY WEDNESDAY WE SHOULD SEE DEEP EASTERLY FLOW SETUP IN THE MID TO UPPER LEVELS AS THE MUCH WEAKENED INVERTED TROUGH SLIDES ACROSS NORTHERN SONORA AND SOUTHERN ARIZONA. THIS FEATURES SHOULD HELP TO ENHANCE ACTIVITY FOR WEDNESDAY...SO I INCREASED POPS SLIGHTLY FOR THAT DAY. BY THURSDAY BOTH THE GFS AND ECMWF SHOW THE INVERTED TROUGH MOVING WEST UNDER THE RIDGE WITH THE GFS A BIT FASTER THAN THE EURO. MEANWHILE...THE CENTER OF THE RIDGE DRIFTS BACK TO A POSITION OVER THE CENTRAL ROCKIES INTO THE PLAINS FOR FRIDAY THROUGH EARLY SATURDAY. THIS WILL SETUP A LONG FETCH OF EAST TO SOUTHEAST FLOW OFF THE WESTERN GULF OF MEXICO THAT COULD BRING AMPLE MOISTURE TO THE REGION. BY LATE SATURDAY AND INTO SUNDAY THE GFS AND EURO SOLUTIONS START TO DIVERGE WITH THE GFS SHOWING THE RIDGE DEVELOPING OVER SRN ARIZONA/NORTHERN SONORA...WITH THE EURO SHOWING THE CENTER OF THE HIGH OVER NEW MEXICO. THE GFS SOLUTION WOULD HAVE A DRIER NORTHWEST FLOW ALOFT OVER ARIZONA...WHILE THE EURO WOULD KEEP A WETTER SOUTH TO SOUTHEAST FLOW. LEANED MORE TOWARD THE EURO SOLUTION WITH SCATTERED POPS MOST AREAS...ISOLATED FOR THE FAR WESTERN ZONES. HIGH TEMPS WILL GENERALLY BE 3 TO 5 DEGS BELOW NORMAL THROUGH WEDNESDAY...THEN NEAR NORMAL THROUGH THE WEEKEND. LOWS WILL BE 1 TO 2 DEGS ABOVE NORMAL THROUGH THURSDAY...THEN 3 TO 5 DEGS ABOVE NORMAL THEREAFTER. && .TWC WATCHES/WARNINGS/ADVISORIES...NONE. $$ DISCUSSION...PYTLAK PREV DISCUSSION...MOLLERE WEATHER.GOV/TUCSON az AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RENO NV 330 AM PDT TUE JUL 22 2008 .SHORT TERM... THE UPPER LOW RESPONSIBLE FOR THE EXCEPTIONAL AMOUNT OF SEVERE WEATHER MONDAY WILL FILL AND EXIT INTO SOUTHEAST OREGON THIS MORNING. WITH A JET STREAK AND UPPER DIFFLUENCE MOVING INTO EXTREME NORTHERN PORTIONS OF THE CWA JUST AHEAD OF THE UPPER LOW...ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE STILL POSSIBLE THIS MORNING...MOSTLY NORTH OF GERLACH. AS FAR AS SEVERITY...WHILE WIND SHEAR ALOFT REMAINS STRONG...INSTABILITY IS WANING ACCORDING TO RUC MODEL FORECASTS SO ANY STORMS MAY TEND TO TEAR APART SOMEWHAT AND/OR REMAIN MODEST IN STRENGTH. AS FAR AS FLASH FLOODING...WITH FAST MOVING THUNDERSTORMS I AM NOT TOO CONCERNED WITH FLASH FLOODING. THEREFORE...I HAVE CANCELLED THE FLASH FLOOD WATCH A COUPLE HOURS EARLY TO COINCIDE WITH THE MORNING FORECAST PACKAGE. AFTER THE UPPER LOW EXITS THIS MORNING...THE REGION WILL SETTLE INTO A DRY SOUTHWEST FLOW ALOFT THROUGH THURSDAY. TEMPERATURES WILL SLOWLY WARM AS AN UPPER RIDGE BUILDS OVERHEAD...WITH HIGHS WINDING UP 5-10 DEGREES ABOVE NORMAL BY THURSDAY. SNYDER .LONG TERM...FRIDAY THROUGH MONDAY... MODELS STILL SHOWING SIMILAR TRENDS THROUGH THE EXTENDED WITH SATURDAY LOOKING TO BE THE MOST INTERESTING DAY ACROSS THE SOUTHERN AND EASTERN ZONES. CENTRAL CONUS RIDGE IS FORECAST TO BUILD INTO THE SOUTHWESTERN U.S. ON FRIDAY HELPING TO TURN OUR FLOW SOUTHERLY WHILE A SHORTWAVE TROUGH DEVELOPS OFF THE NORTHERN CALIFORNIA COAST. MOISTURE WILL BEGIN TO SURGE NORTHWARD INTO SOUTHERN AND EASTERN NEVADA ON FRIDAY. MAINTAINED SLIGHT CHANCE THUNDERSTORMS FOR MONO/MINERAL COUNTIES ON FRIDAY AFTERNOON. THERE ARE TIMING DIFFERENCES BETWEEN THE GFS AND EC...THE EC IS ABOUT 12 HOURS FASTER IN EJECTING THE SHORTWAVE TROUGH THAN THE GFS ON SATURDAY AFTERNOON. WENT AHEAD AND INTRODUCED SLIGHT CHANCE OF THUNDERSTORMS FOR THE SOUTHERN AND FAR EASTERN PORTIONS OF OUR ZONES DURING THE AFTERNOON AS INSTABILITY ASSOCIATED WITH THE UPPER WAVE INCREASES ACROSS THE AREA. KEPT SLIGHT CHANCE WORDING THROUGH SATURDAY NIGHT WITH LOWER CONFIDENCE IN TIMING OF THE UPPER SYSTEM. UPPER WAVE FLATTENS PUSHES RIDGE EASTWARD AND TURNS OUR FLOW SOUTHWESTERLY ON SUNDAY AND MONDAY. EXPECT DRY CONDITIONS ACROSS THE FORECAST AREA WITH ONLY SLIGHT CHANCE OF THUNDERSTORMS OVER MONO AND MINERAL COUNTIES EACH AFTERNOON. CENTRAL CONUS RIDGE IS FORECAST TO BUILD BACK INTO THE DESERT SOUTHWEST ON TUESDAY TURNING THE FLOW ONCE AGAIN MORE SOUTHERLY INCREASING MOISTURE ACROSS SOUTHERN AND EASTERN NEVADA. INCREASED TO SLIGHT CHANCE OF THUNDERSTORMS TUESDAY AFTERNOON ACROSS THE SOUTHERN AND FAR EASTERN PORTIONS OF THE FORECAST AREA. TEMPS WILL REMAIN WARM THROUGH THE WEEKEND WITH HIGHS REACHING TO NEAR 100 THROUGH SUNDAY ACROSS WESTERN NEVADA WHILE THE HIGH SIERRA WILL REACH THE MID 80S. THINGS WILL COOL OFF SLIGHTLY EARLY NEXT WEEK WITH HIGHS INTO THE LOWER TO MID 90S IN WESTERN NEVADA AND LOWER 80S IN THE SIERRA. MOZLEY && .AVIATION... SHOWERS AND THUNDERSTORMS HAVE ENDED OVER MOST OF THE FORECAST AREA EXCEPT FOR AREAS NORTH OF SUSANVILLE AND LOVELOCK WHERE ISOLATED SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH 18Z. QUIET DAY AT THE TERMINALS WITH THE AFTERNOON/EVENING WEST WINDS OFF THE SIERRA. BRONG && .REV WATCHES/WARNINGS/ADVISORIES... NV...NONE. CA...NONE. && $$ HTTP://WEATHER.GOV/RENO ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER CO 305 PM MDT TUE JUL 22 2008 .SHORT TERM...CONVECTION CURRENTLY CONFINED TO HIGHER TERRAIN EAST OF THE CONTINENTAL DIVIDE AS SHOWN BY LATEST RADAR LOOPS. SOME STORMS BEGINNING TO DEVELOP ALONG AND WEST OF THE DIVIDE. NO STORMS YET OVER THE PLAINS. WITH CONTINUED HEATING...SHOULD SEE COVERAGE OF MOUNTAIN STORMS INCREASE BY THE EVENING...WILL CONTINUE THE CURRENT SCATTERED POPS THERE. HARD TO SEE ANY SIGN OF A SHORTWAVE ON SATELLITE WHICH WOULD HELP TO INCREASE COVERAGE. AS FOR PLAINS... AIRMASS STILL SLIGHTLY CAPPED THOUGH LAPS SURFACE ANALYSIS SHOWING CIN ALL BUT GONE. ALSO...ACARS SOUNDINGS INDICATING VERY MINIMAL CIN. SO...POTENTIAL FOR STORMS TO DEVELOP AND MOVE ACROSS PLAINS SLIGHTLY BETTER THAN PREVIOUS DAYS. LOW LEVEL SOUTHEAST FLOW PROVIDING A BOUNDARY ACROSS EASTERN WELD...MORGAN AND CENTRAL ADAMS COUNTIES. CUMULUS HAD BEEN DEVELOPING ALONG THIS BOUNDARY DURING THE PAST HOUR. COULD SEE A FEW STORMS FIRE ALONG THIS BOUNDARY. IN ADDITION...OUTFLOW FROM MOUNTAIN STORMS COULD ALSO BECOME FOCUS FOR CONVECTION. THOUGH RUC KEEPS MOST IF NOT ALL OF THE QPF OVER THE MOUNTAINS TONIGHT...THE NAM AND GFS SPREAD SOME QPF OVER THE PLAINS. GIVEN CURRENT TRENDS...WILL UP THE EVENING POPS TO 30 PERCENT FOR THE URBAN CORRIDOR AND ADJACENT PLAINS. CURRENT INTEGRATED PRECIPITABLE WATER VALUES HOVERING AROUND NINE TENTHS OF AN INCH...COULD ACTUALLY SEE SOME RAINFALL WITH THE STORMS. STEERING WINDS ARE LIGHT...SO STORMS WILL BE SLOW MOVING WITH THE POTENTIAL FOR LOCALLY HEAVY RAIN. MOST ACTIVITY WILL BE ENDING BY MIDNIGHT... THOUGH COULD SEE A FEW STORMS LINGER PAST MIDNIGHT OVER THE MOUNTAINS. ON WEDNESDAY...LITTLE CHANGE IN OVERALL PATTERN EXCEPT THE UPPER LEVEL RIDGE AXIS SHIFTS SLIGHTLY EAST INTO EASTERN COLORADO. THIS COULD BRING MORE OF THE MOISTURE PLUME ACROSS OUR AREA. IN ADDITION..LATEST NAM SHOWING A BATCH OF QG ASCENT IN THE 700-500 MB LAYER ROTATING ACROSS EASTERN COLORADO DURING THE AFTERNOON. THIS FEATURE COULD BE ENOUGH TO AID IN INCREASING CONVECTION CHANCES. FOR NOW WILL LEAVE THE SLIGHT CHANCE POPS ACROSS PLAINS AS FORECAST SOUNDINGS STILL SHOW QUITE A BIT OF CIN DURING THE AFTERNOON. AS FOR MOUNTAINS...SCATTERED POPS SUFFICIENT FOR NOW. FORECAST SOUNDINGS SHOWING PRECIPITABLE WATER VALUES OVER AN INCH ACROSS THE PLAINS...WITH AROUND SEVEN TENTHS OF AN INCH ACROSS THE MOUNTAINS. POTENTIAL EXISTS FOR HEAVY RAIN WITH THE STORMS. TEMPERATURE AND THICKNESS PROGS SHOW LITTE CHANGE FROM TODAY`S PATTERN. HIGHS COULD BE A FEW DEGREES COOLER GIVEN A BIT MORE CLOUD COVER. GUIDANCE INDICATING HIGHS IN THE LOWER AND MID 90S ACROSS THE PLAINS. THIS SEEMS REASONABLE. CURRENT TEMPERATURE GRIDS IN LINE WITH GUIDANCE...LITTLE IF ANY CHANGES NEEDED AT THIS POINT. .LONG TERM...UPPER LEVEL RIDGE WILL REMAIN CENTERED OVER THE SOUTHWESTERN U.S. THROUGH THE WEEKEND AND INTO NEXT WEEK. VERY WARM AND MOSTLY DRY CONDITIONS WILL CONTINUE TO PREVAIL IN THIS PATTERN. BEST CHANCE FOR MOISTURE DURING THE EXTENDED PERIOD WILL BE WEDNESDAY EVENING. MODELS SHOW MOISTURE INCREASING ACROSS THE AREA...LEADING TO GREATER INSTABILITY WHICH SHOULD BE ABLE TO BREAK THE CAP ACROSS THE PLAINS. MOISTURE TO DECREASE THURSDAY AND WE`LL BE BACK TO THE SAME OLD PATTERN OF MOSTLY MOUNTAIN AND FOOTHILL SHOWERS AND THUNDERSTORMS. MODELS HINTING AT SOME SORT OF SHORT WAVE PASSING THROUGH THE RIDGE SUNDAY OR MONDAY. EXPECT AN INCREASE IN THUNDERSTORMS WITH THIS. WILL HOLD FROM INCREASING THE POPS FOR THIS BECAUSE OF THE UNCERTAINTY WITH THE TIMING AND TRACK. HIGH TEMPERATURES WILL REMAIN IN THE 90S ACROSS THE PLAINS EACH DAY. && .AVIATION...ISOLATED THUNDERSTORMS POSSIBLE THROUGH 04Z...WHICH COULD AFFECT AREA AIRPORTS. GUSTY WINDS AND BRIEF HEAVY RAIN POSSIBLE IF STORMS TRACK OVER THE AIRPORTS. VFR CONDITIONS WILL PREVAIL. SOUTHEAST SURFACE GRADIENT TO WEAKEN THIS EVENING...WITH SURFACE WINDS BECOMING DRAINAGE BY 06Z. ISOLATED THUNDERSTORMS POSSIBLE AFTER 18Z WEDNESDAY...PRODUCING GUSTY OUTFLOW WINDS. HEAVY RAIN POSSIBLE WITH THE STORMS...WHICH MAY BRIEFLY LOWER CEILINGS AND VISIBILITY INTO THE MVFR CATEGORY. && .BOU WATCHES/WARNINGS/ADVISORIES...NONE. && D-L/MEIER co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 310 PM EDT TUE JUL 22 2008 .SHORT TERM...TONIGHT THROUGH FRIDAY. THE LATEST SATELLITE IMAGERY SHOWS A SHARP MID TO UPPER LEVEL SHORTWAVE SPINNING JUST NORTH OF OUR GEORGIA ZONES. IN FACT...THE LATEST RUC ANALYSIS SHOWS A CLOSED 500MB CIRCULATION ASSOCIATED WITH THIS FEATURE. THIS WAVE IS PROGGED TO EXPAND SOUTH THIS AFTERNOON AND REMAIN INFLUENTIAL THROUGH MUCH OF THE NIGHT. MODERATE TO STRONG INSTABILITY EXISTS ACROSS MUCH OF THE LOCAL FORECAST AREA AND AMPLE MOISTURE RESIDES THROUGH THE COLUMN. THIS WILL SET THE STAGE FOR STRONG AFTERNOON THUNDERSTORMS TO CARRY INTO THE EVENING AND POSSIBLY EVEN AFTER MIDNIGHT. SEVERE THUNDERSTORMS ARE POSSIBLE...ESPECIALLY GIVEN LARGE CAPE DENSITY VALUES AND COLD TEMPERATURES ALOFT. BOTH LARGE HAIL AND DAMAGING WIND GUSTS WILL BE CONCERNS. SLOW STORM MOVEMENT WILL ALSO RESULT IN VERY HEAVY RAINFALL IN SOME AREAS. GIVEN THE LATEST MODEL DATA WITH UPPER LEVEL SUPPORT REMAINING OVER THE AREA TONIGHT...HAVE DECIDED TO BUMP EVENING POPS UP A LITTLE...INTO THE 40 TO 50 PERCENT RANGE OVER NORTHEAST FLORIDA. EAST COAST SURFACE TROUGH WILL EXTEND SOUTH THROUGH THE LOCAL FORECAST AREA ON WEDNESDAY. UPPER LEVEL PERTURBATIONS WILL ALSO BRUSH THE AREA AS THEY ROTATE AROUND THE BASE OF UPPER TROUGH WHICH WILL BE DIGGING THROUGH THE GREAT LAKES REGION. 850MB WIND MAXIMA WILL APPROACH 20 KNOTS OUT OF THE NORTHWEST BEHIND 850 TROUGH AND THIS WILL AID IN THUNDERSTORM DEVELOPMENT. DEEP CYCLONIC FLOW...AMPLE MOISTURE...AND SUFFICIENT INSTABILITY WILL ALL COMBINE TO PRODUCE SCATTERED TO NUMEROUS THUNDERSTORMS WEDNESDAY AFTERNOON. SEVERE WEATHER WILL AGAIN BE POSSIBLE BUT DEPENDENT ON AMOUNT OF INSOLATION AND REALIZED INSTABILITY. CAPES WILL PROBABLY BE HELD MUCH BELOW TODAYS VALUES GIVEN THE EXTRA CLOUD COVERAGE EXPECTED...HOWEVER...ISOLATED SEVERE THUNDERSTORMS ARE A DECENT BET GIVEN UNSEASONABLY COLD AIR ALOFT. BY THURSDAY...HIGH PRESSURE WILL BEGIN TO BUILD BACK IN. THE NAM AND GFS CONTINUE TO DISAGREE ON POPS THURSDAY AFTERNOON. THE GFS IS MUCH MORE BULLISH (40 TO 60 PERCENT) OPPOSED TO THE NAM SOLUTION OF LESS THAN 20 PERCENT POPS. THE NAM ADVECTS IN MUCH DRIER AIR BEHIND DEPARTING UPPER TROUGH AXIS IN NORTHWEST FLOW ALOFT. WILL CONTINUE TO SIDE CLOSER TO THE GFS. ENOUGH MOISTURE IS EXPECTED TO REMAIN OVER THE AREA FOR TYPICAL SUMMERTIME CONVECTION TO INITIATE ALONG MESOSCALE (SEABREEZE/OUTFLOW) BOUNDARIES. .LONG TERM...SATURDAY THROUGH TUESDAY. LATEST GFS NOW SHOWS AN INTERESTING SOLUTION FOR THE UPCOMING WEEKEND. IT SHOWS THE LARGE UPPER TROUGH OVER THE EAST COAST ATTEMPTING TO DIG BACK DOWN ALL THE WAY INTO FLORIDA ONCE AGAIN...WITH THE ATTENDANT SURFACE TROUGH IN TOW. THIS WOULD RESULT IN ELEVATED CHANCES OF PRECIP WITH POPS HIGHER THAN CLIMO VALUES. WILL CONTINUE WITH 40 PERCENT AFTERNOON POPS FOR NOW BUT IF THE GFS IS CORRECT...THESE VALUES ARE LIKELY A LITTLE ON THE LOW SIDE. NEAR NORMAL TEMPS ARE EXPECTED THROUGH THE EXTENDED PERIOD. && .AVIATION...HAVE CONTINUED TEMPO THUNDER AT ALL SITES THRU THE AFTN...WITH VCTS THRU MID TO LATE EVENING. MAY BE SOME FOG IN RECENT RAIN AREAS TONIGHT AND EVENING SHIFT CAN EVALUATE FURTHER FOG MODIFICATIONS. && .MARINE...HAVE MADE FEW CHANGES TO ONGOING FORECAST. WINDS AND SEAS SHOULD CONTINUE BELOW HEADLINE CRITERIA. && .PRELIMINARY POINT TEMPS/POPS... AMG 73 95 71 94 / 30 40 40 30 SSI 77 92 75 89 / 40 40 40 30 JAX 74 93 73 91 / 40 40 40 30 SGJ 75 91 73 88 / 40 40 40 30 GNV 73 91 72 90 / 50 50 40 40 OCF 72 90 71 88 / 50 50 30 40 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...NONE. GA...NONE. AM...NONE. && $$ SHULER/CARROLL fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MELBOURNE FL 318 AM EDT TUE JUL 22 2008 .DISCUSSION... TODAY/TONIGHT...WEAK SURFACE HIGH PRESSURE ACROSS FLORIDA EARLY THIS MORNING. A FEW LINGERING DEBRIS CLOUDS OVER THE PENINSULA...AND WHILE TC DOLLY IS FAR AWAY OVER WESTERN GULF...SOME CIRRUS FROM SYSTEM BEING CARRIED TOWARD FL VIA ANTICYCLONE ALOFT. LATEST WATER VAPOR IMAGES/RUC ANALYSIS INDICATING SOME CONFLUENCE AND DRIER AIR ALOFT OVER REGION AT PRESENT AND 00Z RUNS OF GFS AND ESPECIALLY NAM ARE INDICATING SOME LOWER PWAT AIR TODAY ESPECIALLY ACROSS NORTHERN SECTIONS. THIS HAS RESULTED IN MODEL POPS COMING IN LOWER THAN PREVIOUS RUNS. WEAK WIND FIELDS WILL ALLOW SEA AND LAKE BREEZES TO FORM WITH DAYTIME HEATING. ENOUGH MOISTURE AND SOME WEAK VORT ENERGY ROTATING DOWN BACK SIDE OF ATLANTIC TROF LATER TODAY TO HELP AID IN STORM DEVELOPMENT BY MID TO LATE AFTERNOON. HAVE DISTRIBUTED POPS FROM SLGT CHC/ISOLATED NORTHERN COASTAL SECTIONS TO LOW END CHC/SCT REMAINDER OF THE AREA WITH ISOLATED ACTIVITY LINGERING INTO EARLY EVENING OVER THE INTERIOR. MORE WARM TEMPS ON TAP WITH SOME MID 90S EXPECTED AGAIN ACROSS THE INTERIOR SECTIONS WHILE SEA BREEZE ONSET SHOULD CAP MAXES NEAR THE EAST COAST IN THE LOWER 90S. WED-MON...VORTICITY MAXIMA ROTATING AROUND AN UPPER LOW THAT IS WOBBLING ABOUT THE UPPER GREAT LAKES/ONTARIO/QUEBEC REGION WILL PUSH THE SURFACE RIDGE/WEAK HIGH PRESSURE UP AND DOWN THE PENINSULA. JUST HOW FAR THE SEA BREEZE PUSHES INLAND EACH DAY REMAINS A BIT TENUOUS. TIME HEIGHT CROSS SECTION RELATIVE HUMIDITY FIELD(S) SHOWED MOST OF THE MOISTURE BELOW 700MB FOR MUCH OF THE FORECAST PERIOD THEREFORE WENT WITH CLIMO POP OF 30/40 DURING THE AFTERNOON AND 20S OVERNIGHT WHICH DID NOT STRAY FAR FROM LATEST EXTENDED (MEX MOS) GUIDANCE. TEMPERATURES AROUND THEIR NORMAL HIGHS OF LOW 90S INLAND AND UPPER 80S ALONG THE COAST DUE TO SEA BREEZE STOPPING DAY TIME HEATING... AND OVERNIGHT LOWS IN THE LOW/MID 70S. && .AVIATION...VFR THROUGH ~18Z THEN TSRA PRODUCING CIG/VSBY REDUCTIONS THROUGH 00Z WILL BE MORE COMMON INTERIOR TAF SITES AND HAVE TEMPO INDICATED INLAND SITES VERSUS A VCTS OR PROB30 EAST COAST LOCATIONS. && .MARINE...WEAK PRESSURE GRADIENT RESULTS IN LIGHT/MODERATE WINDS WITH DAILY SEA BREEZE CIRCULATIONS BEGINNING BY MID AFTERNOON EACH DAY THROUGH THE REMAINDER OF THE WEEK. WINDS LESS THAN 15 KNOTS WITH SOME SEA BREEZE ENHANCE DURING THE AFTERNOON AND EARLY EVENING. SEAS ON THE AVERAGE 3 FEET OR LESS. LONG PERIOD SWELLS STILL NOTED AT OFFSHORE BUOYS AND WILL KEEP RIP CURRENT RISK ELEVATED AGAIN TODAY. && .PRELIMINARY POINT TEMPS/POPS... DAB 93 74 89 72 / 20 20 40 20 MCO 93 74 90 73 / 30 20 40 20 MLB 89 73 89 71 / 30 20 30 20 VRB 90 74 89 73 / 30 10 30 20 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. && $$ SHORT TERM/AVIATION...GLITTO LONG TERM....WIMMER fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 921 PM EDT MON JUL 21 2008 .UPDATE...SHORT WAVE TROUGH HAS BEEN SITUATED OVER GA/SC AND HAS GENERATED SCATTERED STRONG TO SEVERE STORMS OVER CTRL GA THAT MOVED SOUTH INTO THE NRN PORTION OF OUR LOCAL AREA. THE RUC AND NAM INDICATE THIS VORTICITY ASSOCIATED WITH THE SHORT WAVE WILL WEAKEN AS IT MOVES SOUTH. RADAR SHOWS THE STORMS CONSOLIDATING OVER JEFF DAVIS COUNTY AND WEAKENING ON EITHER SIDE. THUS EXPECT THE STRONG ACTIVITY TO DISSIPATE BETWEEN 10 AND 11 PM. A FEW SHOWERS COULD CONTINUE PAST MIDNIGHT AS THE VORTICITY MOVES TOWARD THE AXIS OF THE MEAN LAYER TROUGH ACROSS NORTH FL...BUT THIS AREA WAS WORKED OVER EARLIER IN THE AFTN/EVENING. THE 00Z SOUNDING AT KJAX AND KTAE REVEAL THE 500 MB TEMPS HAVE COOLED TO -8C FROM A WARM -5C DESTABILIZING THE ATMOSHPERE MORE THAN PREVIOUSLY EXPECTED. NOT SURPRISING THEN THAT STORMS DEVELOPED TALL CORES PRODUCING NUMEROUS HAIL REPORTS IN SURROUNDING AREAS. HAVE INCREASED POPS AND SKY COVER ACROSS NORTH PORTION THRU 03Z BUT HAVE MADE NO CHANGES TO THE OVERNIGHT POPS. && .AVIATION...HAZY CONDITIONS WILL CONTINUE TUESDAY AND WILL KEEP 6SM HZ. HAVE MVFR CONDITIONS AT ALL TAF SITES AFTER 06Z TONIGHT WITH A TEMPO FOR IFR TOWARD SUNRISE. && .MARINE...SUSTAINED WINDS ARE AROUND 15 KT AT GRAYS REEF AND THE ST. AUGUSTINE BUOYS WITH HIGHER GUSTS THAT COULD REQUIRE SCEC HEADLINE. A SLY SURGE NEAR SHORE IS LIKELY DUE TO OUTFLOWS AND WILL NOT MAKE ANY CHANGES TO THE WINDS FOR THE UPDATE. SEAS ARE RUNNING 2-3 FT. && .PRELIMINARY POINT TEMPS/POPS... AMG 74 98 73 92 / 40 30 40 50 SSI 77 91 75 90 / 20 30 20 40 JAX 75 95 74 90 / 20 60 30 50 SGJ 76 92 74 89 / 20 50 30 50 GNV 73 94 73 90 / 20 40 40 60 OCF 73 93 72 89 / 10 40 30 50 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...NONE. GA...NONE. AM...NONE. && $$ MKT/MZ/PK fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 859 PM EDT TUE JUL 22 2008 .SYNOPSIS... A TROUGH OF LOW PRESSURE WILL REMAIN INLAND TONIGHT...BUT WILL SHIFT CLOSER TO THE COAST ON WEDNESDAY AND WEDNESDAY NIGHT AS A COLD FRONT APPROACHES FROM THE NORTHWEST. THE COLD FRONT WILL STALL NEAR THE AREA THURSDAY INTO FRIDAY. ATLANTIC HIGH PRESSURE WILL THEN PERSIST INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... SHOWERS/THUNDERSTORMS ARE MOVING INTO THE GEORGIA ZONES FROM THE SOUTHWEST...SO I HAD TO UPDATE THE GRIDS AND TEXT PRODUCTS A BIT EARLY. I RAISED POPS IN THE GEORGIA ZONES AND LOWERED THEM IN THE SOUTH CAROLINA ZONES TO ACCOUNT FOR CURRENT TRENDS. LATEST RUC GUIDANCE SUGGESTS THE THREAT FOR RAIN IN GEORGIA WILL GO ON UNTIL MIDNIGHT OR SHORTLY THEREAFTER BEFORE WINDING DOWN...AND THIS SEEMS REASONABLE GIVEN THE AMOUNT O INSTABILITY STILL AVAILABLE THERE. I ALSO HAD TO MAKE SOME ADJUSTMENTS TO THE EVENING TEMPS AND CLOUDS RELATED TO THE CONVECTION. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... A COLD FRONT WILL APPROACH FROM THE NORTHWEST ON WEDNESDAY...WHILE IT APPEARS THAT A LEE SIDE TROUGH WILL SHIFT CLOSER TO THE COAST SOUTH OF THE FRONT. DEEPER MOISTURE AND THE PROXIMITY OF THE TROUGH/FRONT WILL RESULT IN INCREASED CHANCES OF PRECIPITATION WEDNESDAY INTO WEDNESDAY EVENING...GENERALLY AROUND 40 PERCENT ACROSS THE AREA. PRECIPITABLE WATER VALUES RANGING FROM 2-2.25 INCHES COULD RESULT IN LOCALLY HEAVY RAINFALL. WITH THE LOSS OF HEATING...EXPECT THE COVERAGE OF ANY SHOWERS/THUNDERSTORMS TO DIMINISH SOME WEDNESDAY NIGHT. HIGH TEMPERATURES WEDNESDAY SHOULD BE IN THE MID 90S AWAY FROM THE COAST...WITH LOWS WEDNESDAY NIGHT IN THE LOWER TO MID 70S. && .LONG TERM /THURSDAY THROUGH TUESDAY/... THERE CONTINUES TO BE SOME DISAGREEMENT BETWEEN THE MODELS CONCERNING THE PROGRESSION OF THE COLD FRONT THROUGH THE AREA ON THURSDAY. 12Z GFS KEEPS THE FRONTAL BOUNDARY TO THE NORTH AND SOUTHERLY SURFACE FLOW OVER THE AREA. 12Z NAM PUSHES THE COLD FRONT TO THE GEORGIA/SOUTH CAROLINA COASTAL BORDER BY THURSDAY MORNING...BEFORE STALLING IT OVER NORTHERN FLORIDA BY THURSDAY NIGHT. LATEST ECMWF RUN SHOWS A SIMILAR STALLED FRONT TO THE GFS...BUT ALLOWS DEEPER LAYER DRY AIR TO PUSH INTO THE REGION WITHIN THE INLAND SURFACE TROUGH. WILL LEAN TOWARD THE MORE SEASONAL SOLUTION PROVIDED BY THE GFS. HAVE MAINTAINED SOUTHERLY WINDS ON THURSDAY...WITH POPS IN THE 30 PERCENT RANGE DURING THE AFTERNOON...WHEN INSTABILITY AND SEABREEZE FORCING WILL BE MAXIMIZED. HIGH TEMPERATURES WILL BE A FEW DEGREES COOLER THAN WEDNESDAY...REACHING THE LOWER 90S AWAY FROM THE COAST. UPPER LEVEL RIDGING WILL LINGER OVER THE SOUTHWESTERN STATES THROUGH THE LONG TERM PERIOD...WHILE UPPER TROUGHING REMAINS OVER THE NORTHEAST STATES. A SERIES OF WEAK SHORTWAVES WILL MOVE ALONG THE BASE OF THE UPPER TROUGH OVER THE WEEKEND. THIS UPPER LEVEL ENERGY WILL KEEP A SUFFICIENT MOISTURE PROFILE TO SPARK CONVECTION WITHIN THE AFTERNOON SEABREEZE FORCING. WILL THUS CONTINUE TO REPRESENT A MORE CLIMATOLOGICAL POP SCHEME OF A CHANCE FOR SHOWERS AND THUNDERSTORMS EACH AFTERNOON...DIMINISHING TO NO MORE THAN A SLIGHT CHANCE OVERNIGHT. GFS AMPLIFIES THE UPPER LEVEL ACTIVITY BY LATE SUNDAY...AS ANOTHER WEAK SURFACE FRONT APPROACHES FROM THE NORTHWEST. THERE APPEARS TO BE SOME TIMING AND SENSIBLE WEATHER DIFFERENCES BETWEEN THE ECMWF AND GFS SOLUTIONS THAT LEND UNCERTAINTY IN THE DETAILS FOR LATE WEEKEND INTO THE EARLY NEXT WEEK TIME FRAME. HAVE OPTED TO CONTINUE WITH A MORE GENERAL CONVECTIVE FORECAST OF CHANCE POPS DURING THE DAYTIME HOURS...UNTIL MORE CONSISTENT TRENDS ARE SEEN IN THE MODEL FORECASTS. HIGH TEMPERATURES THROUGH THE PERIOD WILL RANGE WITHIN A FEW DEGREES OF SEASONAL NORMS...WARMING INTO THE LOWER 90S EACH AFTERNOON. HEAT INDICES WILL GENERALLY REMAIN BELOW 103 DEGREES THROUGH THE WEEKEND...WITH INDICES AS HIGH AS 105 IN SOME AREAS BY EARLY NEXT WEEK. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... VFR CONDITIONS EXPECTED TO CONTINUE FOR BOTH KCHS AND KSAV FOR THE NEXT 24 HOUR PERIOD. DEBRIS CLOUDINESS FROM EARLIER CONVECTION SHOULD AFFECT BOTH TERMINALS THROUGH WEDNESDAY MORNING...ESPECIALLY FOR KSAV. HAVE INCLUDE HAZE POTENTIAL FOR KSAV AFTER 06Z...WITH LIGHT WINDS AND LOW-LEVEL MOISTURE THE POTENTIAL LOOKS HIGHER THAN IN KCHS...YET KEPT VISIBILITIES VFR. ISOLATED CONVECTION COULD DEVELOP FOR WEDNESDAY AFTERNOON AS AN APPROACHING COLD FROM THE NORTHWEST AND THE AFTERNOON SEA BREEZE MOVE INTO THE AREA...THEREFORE INCLUDED CB GROUPS FOR BOTH TERMINALS AFTER 18Z. EXTENDED AVIATION OUTLOOK...A CHANCE OF MVFR VSBYS EACH MORNING DUE TO HIGH LOW LEVEL MOISTURE AND LIGHT WINDS...OTHERWISE VFR CONDITIONS EXPECTED OUTSIDE OF MAINLY AFTERNOON/EVENING CONVECTION. && .MARINE... FAIRLY TRANQUIL CONDITIONS EXPECTED THROUGH SUNDAY. THE MARINE ZONES WILL REMAIN ON THE WESTERN PERIPHERY OF ATLANTIC HIGH PRESSURE. WINDS WILL GENERALLY MAINTAIN A SOUTHERLY COMPONENT THROUGH THE PERIOD. SPEEDS WILL REMAIN AT OR BELOW 15 KNOTS OUTSIDE OF ANY THUNDERSTORM ACTIVITY...WITH SEAS AT OR BELOW 4 FEET. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...NONE. && $$ ALSHEIMER ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 1252 PM CDT MON JUL 21 2008 .DISCUSSION... 345 AM CDT MAIN FOCUS IN SHORT TERM IS ON SEVERE MCS CURRENTLY ACROSS IOWA AND ASSOCIATED PROPAGATION AND TRENDS OVER NEXT SEVERAL HOURS THIS MORNING. CONVECTION DEVELOPED A LITTLE FARTHER WEST/LATER THAN ANTICIPATED FROM YESTERDAY...THOUGH MCS HAS DEVELOPED ALONG/NORTH OF EFFECTIVE FRONTAL BOUNDARY ACROSS NEB/IA AND IN ASSOCIATION WITH 35 KNOT SOUTHWESTERLY LOW LEVEL JET INDUCED BY SHORT WAVE NOTED IN VAPOR IMAGERY ACROSS THE DAKOTAS. LATEST RUC/SPC MESOANALYSIS GUIDANCE INDICATES FAIRLY IMPRESSIVE MLCAPE AXIS EXTENDING FROM SOUTHERN IOWA INTO CENTRAL IL..WHERE SURFACE DEWPOINTS ARE POOLED IN THE LOW/MID 70S. THOUGH LOW LEVEL JET PROGGED TO VEER MORE WESTERLY AND WEAKEN WITH TIME THIS MORNING...EXPECT THIS MCS WILL CONTINUE TO PROPAGATE EAST/SOUTHEAST TOWARD CENTRAL ILLINOIS AND WILL LIKELY AFFECT ESPECIALLY SOUTH/SOUTHWEST PARTS OF WFO CHICAGO CWA. WITH SUBSTANTIAL INSTABILITY AND LOCATION ALONG SOUTHERN PERIPHERY OF 40-50 KNOT 0-6 KM DEEP SHEAR WILL LIKELY CONTINUE TO SEE SOME SEVERE WEATHER POTENTIAL WITH THESE STORMS...AS WELL AS THE POTENTIAL FOR LOCALLY HEAVY RAINFALL AS RUC/NAM/GFS ALL DEPICT PWATS INCREASING ABOVE 1.5 INCHES THIS MORNING. HAVE INITIALLY DELINEATED MAINLY AREAS SOUTH OF ILLINOIS AND KANKAKEE RIVER VALLEYS FOR HIGHEST POPS THIS MORNING...DECREASING FAIRLY SHARPLY TO THE NORTHEAST INTO THE RFD/CHI METRO AREAS. WILL LIKELY MAKE SOME LAST MINUTE ADJUSTMENTS BASED ON REGIONAL RADAR TRENDS HOWEVER. EXPECT THUNDERSTORMS TO CONTINUE TO PROPAGATE TO THE EAST/SOUTHEAST ACROSS CENTRAL IL/IND THROUGH LATE MORNING/EARLY AFTERNOON WITH FOCUS GRADUALLY SHIFTING FARTHER TO THE SOUTH AS OUTFLOW SPREADS DOWNSTATE. MEANWHILE...FARTHER NORTH ADDITIONAL PRECIPITATION IS MOVING INTO WESTERN MN THIS MORNING ALSO IN ASSOCIATION WITH DAKOTAS SHORT WAVE. NAM INDICATES THIS DISTURBANCE WILL SLIP INTO SOUTHERN WI/NORTHERN IL BY LATE MORNING/AFTERNOON. WHILE INSTABILITY AND LOW LEVEL FORCING NOT NEARLY AS IMPRESSIVE ACROSS NORTHERN COUNTIES...FORECAST SOUNDINGS DO DEPICT ELEVATED CAPES ON ORDER OF 600-800 J/KG AND THUS WILL CARRY A SLIGHT CHANCE POP ACROSS THE NORTH THIS AFTERNOON. ONE OTHER WRINKLE THIS MORNING IS THAT SOME PATCHY DENSE FOG HAS DEVELOPED ACROSS SOUTH/SOUTHEAST COUNTIES WHERE SKIES HAD EARLIER BEEN RELATIVELY CLOUD FREE. AT THIS TIME DOES NOT APPEAR TO BE DENSE/WIDESPREAD ENOUGH TO WARRANT AN ADVISORY...AND WILL HANDLE WITH JUST A MENTION OF AREAS OF FOG THERE THIS MORNING. OTHERWISE...LARGE SCALE PATTERN SHIFT IS UNDERWAY WITH UPPER RIDGE BUILDING ACROSS THE ROCKIES AND NORTHERN HIGH PLAINS...AND RESULTING DOWNSTREAM AMPLIFICATION OF UPPER TROUGH OVER EASTERN CANADA/CONUS. GOES VAPOR IMAGERY INDICATES SEVERAL INDIVIDUAL MID LEVEL CIRCULATIONS WHICH WILL ROTATE SOUTHEAST ACROSS GREAT LAKES REGION INTO WEST SIDE OF LARGER SCALE TROUGH NEXT 36-48 HOURS...WITH LIGHT SPORADIC QPF GENERATED BY VARIOUS MODELS ACROSS THE UPPER MIDWEST NEXT COUPLE OF DAYS. AFTER MAIN AREA OF PRECIPITATION AND CONVECTION SHIFTS SOUTH TONIGHT...APPEARS TUESDAY AFTERNOON WOULD HAVE THE HIGHEST POTENTIAL FOR CONVECTION AS MID LEVEL COLD POCKET SLIDES SOUTHEAST ACROSS WI/FAR NORTHERN IL DURING THE AFTERNOON. BASED ON THIS WILL ADD A LOW CHANCE POP FOR SHOWERS/ISOLATED THUNDER ACROSS AREAS MAINLY NORTH OF INTERSTATE 80 IN NORTHERN IL FOR TUESDAY AFTERNOON. SURFACE HIGH PRESSURE THEN BUILDS SOUTHWARD ACROSS THE WESTERN GREAT LAKES WEDNESDAY AS MAIN UPPER TROUGH AXIS SHIFTS OVER THE EASTERN LAKES AND UPPER OHIO VALLEY. SPELL OF SLIGHTLY COOLER THAN NORMAL TEMPS AND DRY WEATHER EXPECTED DURING THIS PERIOD...WITH 00Z GFS/ECMWF RUNS SLOWING RETURN OF MOISTURE A BIT ON THURSDAY. SFC RIDGE EVENTUALLY BREAKS DOWN AND SHIFTS EAST FRIDAY HOWEVER...AS FAIRLY SIGNIFICANT SHORT WAVE DEPICTED TOPPING WESTERN RIDGE AND MOVING ACROSS UPPER MIDWEST LATE WEEK. THIS EXPECTED TO SLIDE ANOTHER FRONT THROUGH FRIDAY...WITH DRY WEATHER RETURNING SATURDAY AS SURFACE HIGH PRESSURE AGAIN BUILDS ACROSS UPPER MIDWEST/NORTHERN LAKES. RATZER && .AVIATION... 18Z TAFS...COLD FRONT PUSHED QUICKLY INTO FAR NORTHEAST IL LATE THIS MORNING WITH IFR/LIFR CIGS ALONG THE SHORE. APPEARED THIS WOULD CONTINUE PUSHING SOUTH ACROSS NORTHEAST IL INTO NORTHWEST INDIANA. BUT FRONT HAS NOW SLOWED AND LOW CLOUDS APPEAR TO BE MAINLY OVER THE WATER...HAVING LIFTED SOME ACROSS FAR NORTHEAST IL AND SOUTHEAST WI. THUS...HAVE REMOVED LOW CLOUDS FROM LATE MORNING AMENDMENT. STILL COULD BE SOME IFR ALONG THE LAKESHORE BUT NOT EXPECTING ANYTHING MORE THAN SCATTERED PERHAPS BKN 2-3KFT CLOUDS ACROSS THE TERMINALS THIS AFTERNOON. TIMING OF FRONTAL PASSAGE DIFFICULT BUT EXPECT NORTHWEST WINDS TO SLOWLY TURN NORTH/NORTHEAST BUT SPEEDS ONLY 10-15KTS. WINDS TURN MORE NORTHEAST THIS EVENING THEN BACK NORTHERLY TUESDAY MORNING. COULD BE SOME LIGHT FOG ACROSS PARTS OF THE AREA TUESDAY MORNING BUT WILL LET NEXT FORECAST TAKE A CLOSER LOOK AT FOG POTENTIAL. CHANCE OF A FEW SHOWERS TOWARD THE END OF THE PERIOD INTO TUESDAY AFTERNOON...ESPECIALLY TOWARD THE WI BORDER. MAY NEED TO ADD SOME LIGHT SHOWERS FOR TUESDAY AFTERNOON WITH THE NEXT FORECAST. CMS && .MARINE... 1252 PM...A COLD FRONT OVER SOUTHERN LAKE MICHIGAN WILL CONTINUE TO SLOWLY MOVE SOUTH ACROSS THE OHIO VALLEY TONIGHT. HIGH PRESSURE OVER HUDSON BAY AND NORTHERN ONTARIO WILL BUILD SOUTH ACROSS THE NORTHERN LAKES TONIGHT AND TUESDAY...THEN ACROSS THE WESTERN LAKES AND NORTHERN ILLINOIS INTO WEDNESDAY...WITH NORTHERLY WINDS EXPECTED THROUGH THURSDAY MORNING. CMS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 726 PM MDT TUE JUL 22 2008 .UPDATE... 714 PM MDT TUE JUL 22 2008 JUST COMPLETED AN UPDATE. MAIN CHANGE WAS TO REMOVE PRECIPITATION. CAP IS STRENGTHENING OVER THE AREA AND IS ALREADY STRONG ON TOP OF OUR STATIONARY FRONT. ALSO HEIGHTS/RIDGE BUILDING OVER THE AREA WITH LITTLE IF ANY LIFT NOTED ON SATELLITE. ADJUSTED CLOUD COVER TO ACCOUNT FOR MUCH LESS IN THE EVENING AND MORE OVERNIGHT. KEPT THE AREAS OF FOG IN EVEN THOUGH NAM/RUC NOT AS AGGRESSIVE TONIGHT WITH FOG FORMATION. HOWEVER...MODELS UNDERDID MOISTURE ADVECTION LAST NIGHT AND HAVE DECENT UPSLOPE FLOW. OTHERWISE DID MINOR TWEEKS ON OTHER ELEMENTS BASED ON CURRENT TRENDS. BULLER && .DISCUSSION...FORECAST CONCERNS ARE ON EXTENT OF FOG TONIGHT FOLLOWED BY TEMPERATURES AND PRECIPITATION THROUGH THE NEXT 7 DAYS. STATIONARY BOUNDARY CURRENTLY ALONG OR JUST NORTH OF THE INTERSTATE AND WILL ACT AS A FOCUS FOR SHOWERS AND THUNDERSTORMS THIS EVENING. AFTER MIDNIGHT FOG WILL REDEVELOP AND BASED ON THE NAM (WHICH ACTUALLY VERIFIED THIS WELL ON YESTERDAYS MODEL RUN) WILL COVER THE NORTHEAST 1/2 OF THE AREA THROUGH 15Z OR SO BEFORE LIFTING NORTHEAST AND DISSIPATING. FOR TUESDAY NIGHT THROUGH FRIDAY UPPER LEVEL FLOW WILL INCREASE A BIT WHILE ALSO FLATTENING OUT ALLOWING FOR AN INCREASED CHANCE OF PRECIPITATION...MAINLY ACROSS THE NORTHWEST AND WESTERN PARTS OF THE AREA. AFTERNOON TEMPERATURES WILL BE HOT AGAIN WEDNESDAY WITH HIGHS AROUND 100 BUT A VERY SLIGHT COOLING TREND IS EXPECTED AS INCREASING CLOUDINESS WITH THE DEAMPLIFIED TROUGH MOVES IN. BY THURSDAY LOW TO MID 90S ARE EXPECTED. SATURDAY THROUGH TUESDAY...A GENERAL BROAD UPPER RIDGE BUILDS SLIGHTLY ON SATURDAY AND CONTINUES THROUGH TUESDAY WITH TEMPERATURES REMAINING IN THE 90S. TYPICAL OF THIS TIME OF YEAR AFTERNOON AND EVENING THUNDERSTORMS ARE POSSIBLE. WITHOUT A STRONG SIGN OR AGREEMENT ON ANY DISTURBANCES TO KICK THEM OFF WILL MAINTAIN SLIGHT CHANCE POPS. DDT && .AVIATION... 714 PM MDT TUE JUL 22 2008 UPDATE FOR THE 00Z TAFS...CAP HAS STRENGTHENED OVER THE AREA WITH MID LEVEL RIDGE BUILDING IN...AND WILL REMOVE WHAT LITTLE MENTION THERE IS OF CONVECTION FROM THE KMCK TAF. NEXT PROBLEM WILL BE HOW MUCH STRATUS AND FOG REDEVELOP TONIGHT. WITH FRONT AND EASTERLY WINDS TO STAY IN PLACE...WOULD THINK THAT A REPEAT IS IN STORE. BUT EVEN THE NAM/RUC WHICH GOT IT RIGHT LAST NIGHT IS NOT SHOWING ANY REDUCTIONS IN VISIBILITY. MADE THE KGLD TAF MORE OPTIMISTIC...AND PUT THE LOWER CEILINGS AND VISIBILITY AT THE KMCK TAF. WILL HAVE TO FINE TUNE THESE WITH THE NEXT ISSUANCE. BULLER && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 553 PM MDT TUE JUL 22 2008 .DISCUSSION...FORECAST CONCERNS ARE ON EXTENT OF FOG TONIGHT FOLLOWED BY TEMPERATURES AND PRECIPITATION THROUGH THE NEXT 7 DAYS. STATIONARY BOUNDARY CURRENTLY ALONG OR JUST NORTH OF THE INTERSTATE AND WILL ACT AS A FOCUS FOR SHOWERS AND THUNDERSTORMS THIS EVENING. AFTER MIDNIGHT FOG WILL REDEVELOP AND BASED ON THE NAM (WHICH ACTUALLY VERIFIED THIS WELL ON YESTERDAYS MODEL RUN) WILL COVER THE NORTHEAST 1/2 OF THE AREA THROUGH 15Z OR SO BEFORE LIFTING NORTHEAST AND DISSIPATING. FOR TUESDAY NIGHT THROUGH FRIDAY UPPER LEVEL FLOW WILL INCREASE A BIT WHILE ALSO FLATTENING OUT ALLOWING FOR AN INCREASED CHANCE OF PRECIPITATION...MAINLY ACROSS THE NORTHWEST AND WESTERN PARTS OF THE AREA. AFTERNOON TEMPERATURES WILL BE HOT AGAIN TUESDAY WITH HIGHS AROUND 100 BUT A VERY SLIGHT COOLING TREND IS EXPECTED AS INCREASING CLOUDINESS WITH THE DEAMPLIFIED TROUGH MOVES IN. BY THURSDAY LOW TO MID 90S ARE EXPECTED. SATURDAY THROUGH TUESDAY...A GENERAL BROAD UPPER RIDGE BUILDS SLIGHTLY ON SATURDAY AND CONTINUES THROUGH TUESDAY WITH TEMPERATURES REMAINING IN THE 90S. TYPICAL OF THIS TIME OF YEAR AFTERNOON AND EVENING THUNDERSTORMS ARE POSSIBLE. WITHOUT A STRONG SIGN OR AGREEMENT ON ANY DISTURBANCES TO KICK THEM OFF WILL MAINTAIN SLIGHT CHANCE POPS. DDT && .AVIATION... 542 PM MDT TUE JUL 22 2008 FOR THE 00Z TAFS...CURRENTLY HAVE STATIONARY FRONT DRAPED FROM NORTHWEST TO SOUTHEAST ACROSS THE CENTER OF THE FORECAST AREA. WOULD THINK THIS WOULD BE A GOOD FOCUS FOR THUNDERSTORMS. HOWEVER PER LAPS AND SATELLITE...LOW LEVEL AIR MASS APPEARS TO BE CAPPED ESPECIALLY ON TOP OF THE FRONT. LITTLE IF ANY LIFT IN PLACE ALOFT AND ONLY GETS WORSE WITH RISING HEIGHTS THROUGH THE EVENING. AS A RESULT AM PESSIMISTIC ABOUT ANY THUNDERSTORMS DEVELOPING. LEFT THE MENTION OF CB IN THE KMCK TAF SINCE IT IS CLOSEST TO THE FRONT. NEXT PROBLEM WILL BE HOW MUCH STRATUS AND FOG REDEVELOP TONIGHT. WITH FRONT AND EASTERLY WINDS TO STAY IN PLACE...WOULD THINK THAT A REPEAT IS IN STORE. BUT EVEN THE NAM/RUC WHICH GOT IT RIGHT LAST NIGHT IS NOT SHOWING ANY REDUCTIONS IN VISIBILITY. MADE THE KGLD TAF MORE OPTIMISTIC...AND PUT THE LOWER CEILINGS AND VISIBILITY AT THE KMCK TAF. WILL HAVE TO FINE TUNE THESE WITH THE NEXT ISSUANCE. BULLER && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 635 PM CDT TUE JUL 22 2008 .UPDATE... UPDATED FOR 00 UTC AVIATION. && .DISCUSSION... SEE PREVIOUS DISCUSSION. && .AVIATION... PRESENCE OF OUTFLOW BOUNDARIES...A WEAK UPPER WAVE...AND PLENTY OF INSTABILITY SUGGEST SOME CONVECTIVE CONCERNS FOR THE TERMINALS. WILL GO WITH CB FOR THE EARLY EVENING UNTIL INSTABILITY WANES AS THE CHANCES OF A TS IN THE AERODROMES SEEM REMOTE. WINDS SHOULD GENERALLY BE LIGHT AND EASTERLY...WITH AN INCREASE IN SPEEDS BY LATE WEDNESDAY MORNING. VFR CONDITIONS ARE EXPECTED THROUGHOUT THE 00Z CYCLE. && .PREV DISCUSSION... /ISSUED 344 PM CDT TUE JUL 22 2008/ DISCUSSION... WEAK SURFACE BOUNDARY JUST SOUTH OF I70 AT 20Z. MESOANALYSES SHOW SOME SURFACE CONVERGENCE ALONG BOUNDARY...AND WEAK CAP. DEWPOINTS HAVE POOLED JUST NORTH OF FRONT...WITH MIXED LAYER CAPES NEAR 4000 J/KG. HOWEVER...NO SIGNIFICANT CONVECTION HAS FIRED AND NOTHING APPEARS IMMINENT ON SATELLITE IMAGERY. RUC ANALYSIS AND PROFILER WINDS SHOWS WEAK VORT MAX OVER ERN NEBRASKA MOVING SE. HOWEVER...SUBSIDENCE IN WAKE OF THIS MORNINGS MISSOURI MCS HAS HELPED WITH OVERALL CONVECTIVE SUPPRESSION. WITH BOUNDARY REMAINING IN AREA...EXPECT ISOLATED CONVECTION TO STILL BE POSSIBLE TONIGHT INTO WEDNESDAY AS WEAK POSITIVE 850 MB THETA-E ADVECTION CONTINUES. POPS KEPT AOB 20 PERCENT TONIGHT AND WEDNESDAY. RELATIVELY HIGH DEWPOINTS ACROSS ERN KS SHOULD KEEP LOW TEMPS IN THE UPPER 60S TO LOWER 70S. ON WEDNESDAY...GFS MOS GUIDANCE WARMER THAN NAM OR NGM AND HAVE GONE CLOSER TO THIS BASED ON RECENT PERFORMANCE. PHILLIPS WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...THE UPPER RIDGE WILL AMPLIFY ACROSS THE SOUTHERN PLAINS WHILE AN UPPER LEVEL TROUGH MOVES EAST ACROSS THE NORTHERN PLAINS INTO THE UPPER MIDWEST. WEDNESDAY NIGHT INTO THURSDAY MORNING THERE MAY BE A SLIGHT CHANCE FOR ELEVATED SHOWERS AND THUNDERSTORMS TO DEVELOP AS WAA/ISENTROPIC LIFT INCREASES ACROSS THE NORTHERN AND EASTERN PORTIONS OF THE CWA...BUT BEING UNDER THE 5H RIDGE AXIS MAY INHIBIT THE DEVELOPMENT OF ELEVATED THUNDERSTORMS. AS THE 5H TROUGH MOVES ACROSS THE NORTHERN HIGH PLAINS THEN DIGS SOUTHEAST INTO THE GREAT LAKES...A WEAK COLD FRONT WILL MOVE SOUTHWARD ACROSS NE AND INTO NORTH CENTRAL KS DURING THE AFTERNOON HOURS. THERE MAY BE ENOUGH SFC CONVERGENCE FOR ISOLATED THUNDERSTORMS TO DEVELOP THURSDAY AFTERNOON ACROSS THE NORTH CENTRAL KANSAS ALONG THE COLD FRONT. HIGHS ON THURSDAY MAY BE CLOSE TO 100 DEGREES ACROSS THE SOUTHWEST AND WEST CENTRAL CWA...WITH LOWER 90S ACROSS THE NORTHEAST COUNTIES OF THE CWA. THE FRONT WILL MOVE SOUTHEAST ACROSS THE NORTHERN AND EASTERN CWA PROVIDING AT LEAST A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS THURSDAY NIGHT. FRIDAY THROUGH SATURDAY NIGHT...THE WEAK FRONT WILL MOVE SOUTHWARD AND STALL OUT AND WEAKEN ALONG I-70. THE 5H TROUGH OVER THE MIDWEST WILL DIG SOUTHEAST INTO THE GREAT LAKES STATES. BOTH THE ECMWF AND GFS SHOW THE SOUTHERN PLAINS 5H RIDGE RE-AMPLIFYING. SYNOPTIC SCALE SUBSIDENCE UNDER THE 5H RIDGE SHOULD CREATE AN ENVIRONMENT UNFAVORABLE FOR DEEP MOIST CONVECTION...BUT I CANNOT RULE OUT PULSE STORMS DEVELOPING ALONG OR NORTH OF THE BOUNDARY DURING THE LATE AFTERNOON HOURS FRIDAY...GIVEN DEEP MOISTURE AND STRONG SFC HEATING. THEREFORE...I KEPT A 14 POP DURING THE DAY FRIDAY AND 15 POPS FRIDAY EVENING. TEMPERATURES ACROSS THE NORTHERN COUNTIES MAY ONLY REACH THE LOWER TO MID 90S NORTH OF THE WEAK SFC BOUNDARY. SOUTH OF THE SFC BOUNDARY HIGHS WILL BE IN THE UPPER 90S...POSSIBLY NEAR 100 DEGREES OVER THE SOUTHERN COUNTIES OF THE CWA. ON SATURDAY BOTH THE ECMWF AND GFS SHOW THE 5H RIDGE AXIS RETROGRADING INTO THE WEST CENTRAL CONUS AS A LONGER WAVE LENGTH 5H TROUGH OVER THE EASTERN CONUS AMPLIFIES. HIGH TEMPERATURES MAY BE A FEW DEGREES COOLER AS THE CENTER OF THE RIDGE AXIS SHIFTS WEST OF THE SOUTHERN PLAINS. HIGHS ON SATURDAY WILL BE IN THE MID 90S ACROSS MOST OF THE CWA. SATURDAY NIGHT THROUGH TUESDAY...BOTH THE ECMWF AND GFS KEEP A LONGER WAVE LENGTH 5H TROUGH ACROSS THE EASTERN CONUS AND A BROAD 5H RIDGE ACROSS THE WEST CENTRAL CONUS. THE ECMWF IS A BIT MORE AMPLIFIED WITH THE 5H TROUGH OVER THE EASTERN CONUS...AND BRINGS A COLD FRONT SOUTHWESTWARD INTO THE CWA SUNDAY INTO MONDAY. THIS WOULD PROVIDE THE CWA WITH A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS SATURDAY NIGHT THROUGH SUNDAY NIGHT. HOWEVER...THE GFS IS NOT AS AMPLIFIED WITH THE EASTERN CONUS 5H TROUGH AND KEEPS THE FRONT NEARLY STATIONARY ACROSS EASTERN NE...SOUTHEAST INTO WESTERN MO. IF THE GFS WERE TO VERIFY THE BEST RAIN CHANCES WILL REMAIN NORTH AND EAST OF THE CWA. THEREFORE...I PLACED IN SLIGHT CHANCES FOR THUNDERSTORMS SATURDAY NIGHT THROUGH SUNDAY NIGHT ACROSS THE CWA. THE ECMWF MODEL FORECAST SHOWS THE FRONT MOVING SOUTHWARD INTO NORTHERN OK MONDAY AND TUESDAY...AND THE GFS MODEL SOLUTION KEEPS THE FRONT NORTHEAST OF THE CWA...THEREFORE I KEPT POPS AT 14 PERCENT MONDAY NIGHT AND TUESDAY. HIGHS SUNDAY THROUGH TUESDAY WILL ONLY REACH THE LOWER TO MID 90S...SINCE THE 5H RIDGE AXIS WILL SHIFT FARTHER WEST. HIGH MAY BE A BIT COOLER ON SUNDAY AND MONDAY IF THE ECMWF SOLUTION WERE TO VERIFY BRING THE SFC COLD FRONT SOUTHWEST ACROSS THE CWA. GARGAN && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ 65 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 344 PM CDT TUE JUL 22 2008 .DISCUSSION... WEAK SURFACE BOUNDARY JUST SOUTH OF I70 AT 20Z. MESOANALYSES SHOW SOME SURFACE CONVERGENCE ALONG BOUNDARY...AND WEAK CAP. DEWPOINTS HAVE POOLED JUST NORTH OF FRONT...WITH MIXED LAYER CAPES NEAR 4000 J/KG. HOWEVER...NO SIGNIFICANT CONVECTION HAS FIRED AND NOTHING APPEARS IMMINENT ON SATELLITE IMAGERY. RUC ANALYSIS AND PROFILER WINDS SHOWS WEAK VORT MAX OVER ERN NEBRASKA MOVING SE. HOWEVER...SUBSIDENCE IN WAKE OF THIS MORNINGS MISSOURI MCS HAS HELPED WITH OVERALL CONVECTIVE SUPPRESSION. WITH BOUNDARY REMAINING IN AREA...EXPECT ISOLATED CONVECTION TO STILL BE POSSIBLE TONIGHT INTO WEDNESDAY AS WEAK POSITIVE 850 MB THETA-E ADVECTION CONTINUES. POPS KEPT AOB 20 PERCENT TONIGHT AND WEDNESDAY. RELATIVELY HIGH DEWPOINTS ACROSS ERN KS SHOULD KEEP LOW TEMPS IN THE UPPER 60S TO LOWER 70S. ON WEDNESDAY...GFS MOS GUIDANCE WARMER THAN NAM OR NGM AND HAVE GONE CLOSER TO THIS BASED ON RECENT PERFORMANCE. PHILLIPS WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...THE UPPER RIDGE WILL AMPLIFY ACROSS THE SOUTHERN PLAINS WHILE AN UPPER LEVEL TROUGH MOVES EAST ACROSS THE NORTHERN PLAINS INTO THE UPPER MIDWEST. WEDNESDAY NIGHT INTO THURSDAY MORNING THERE MAY BE A SLIGHT CHANCE FOR ELEVATED SHOWERS AND THUNDERSTORMS TO DEVELOP AS WAA/ISENTROPIC LIFT INCREASES ACROSS THE NORTHERN AND EASTERN PORTIONS OF THE CWA...BUT BEING UNDER THE 5H RIDGE AXIS MAY INHIBIT THE DEVELOPMENT OF ELEVATED THUNDERSTORMS. AS THE 5H TROUGH MOVES ACROSS THE NORTHERN HIGH PLAINS THEN DIGS SOUTHEAST INTO THE GREAT LAKES...A WEAK COLD FRONT WILL MOVE SOUTHWARD ACROSS NE AND INTO NORTH CENTRAL KS DURING THE AFTERNOON HOURS. THERE MAY BE ENOUGH SFC CONVERGENCE FOR ISOLATED THUNDERSTORMS TO DEVELOP THURSDAY AFTERNOON ACROSS THE NORTH CENTRAL KANSAS ALONG THE COLD FRONT. HIGHS ON THURSDAY MAY BE CLOSE TO 100 DEGREES ACROSS THE SOUTHWEST AND WEST CENTRAL CWA...WITH LOWER 90S ACROSS THE NORTHEAST COUNTIES OF THE CWA. THE FRONT WILL MOVE SOUTHEAST ACROSS THE NORTHERN AND EASTERN CWA PROVIDING AT LEAST A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS THURSDAY NIGHT. FRIDAY THROUGH SATURDAY NIGHT...THE WEAK FRONT WILL MOVE SOUTHWARD AND STALL OUT AND WEAKEN ALONG I-70. THE 5H TROUGH OVER THE MIDWEST WILL DIG SOUTHEAST INTO THE GREAT LAKES STATES. BOTH THE ECMWF AND GFS SHOW THE SOUTHERN PLAINS 5H RIDGE RE-AMPLIFYING. SYNOPTIC SCALE SUBSIDENCE UNDER THE 5H RIDGE SHOULD CREATE AN ENVIRONMENT UNFAVORABLE FOR DEEP MOIST CONVECTION...BUT I CANNOT RULE OUT PULSE STORMS DEVELOPING ALONG OR NORTH OF THE BOUNDARY DURING THE LATE AFTERNOON HOURS FRIDAY...GIVEN DEEP MOISTURE AND STRONG SFC HEATING. THEREFORE...I KEPT A 14 POP DURING THE DAY FRIDAY AND 15 POPS FRIDAY EVENING. TEMPERATURES ACROSS THE NORTHERN COUNTIES MAY ONLY REACH THE LOWER TO MID 90S NORTH OF THE WEAK SFC BOUNDARY. SOUTH OF THE SFC BOUNDARY HIGHS WILL BE IN THE UPPER 90S...POSSIBLY NEAR 100 DEGREES OVER THE SOUTHERN COUNTIES OF THE CWA. ON SATURDAY BOTH THE ECMWF AND GFS SHOW THE 5H RIDGE AXIS RETROGRADING INTO THE WEST CENTRAL CONUS AS A LONGER WAVE LENGTH 5H TROUGH OVER THE EASTERN CONUS AMPLIFIES. HIGH TEMPERATURES MAY BE A FEW DEGREES COOLER AS THE CENTER OF THE RIDGE AXIS SHIFTS WEST OF THE SOUTHERN PLAINS. HIGHS ON SATURDAY WILL BE IN THE MID 90S ACROSS MOST OF THE CWA. SATURDAY NIGHT THROUGH TUESDAY...BOTH THE ECMWF AND GFS KEEP A LONGER WAVE LENGTH 5H TROUGH ACROSS THE EASTERN CONUS AND A BROAD 5H RIDGE ACROSS THE WEST CENTRAL CONUS. THE ECMWF IS A BIT MORE AMPLIFIED WITH THE 5H TROUGH OVER THE EASTERN CONUS...AND BRINGS A COLD FRONT SOUTHWESTWARD INTO THE CWA SUNDAY INTO MONDAY. THIS WOULD PROVIDE THE CWA WITH A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS SATURDAY NIGHT THROUGH SUNDAY NIGHT. HOWEVER...THE GFS IS NOT AS AMPLIFIED WITH THE EASTERN CONUS 5H TROUGH AND KEEPS THE FRONT NEARLY STATIONARY ACROSS EASTERN NE...SOUTHEAST INTO WESTERN MO. IF THE GFS WERE TO VERIFY THE BEST RAIN CHANCES WILL REMAIN NORTH AND EAST OF THE CWA. THEREFORE...I PLACED IN SLIGHT CHANCES FOR THUNDERSTORMS SATURDAY NIGHT THROUGH SUNDAY NIGHT ACROSS THE CWA. THE ECMWF MODEL FORECAST SHOWS THE FRONT MOVING SOUTHWARD INTO NORTHERN OK MONDAY AND TUESDAY...AND THE GFS MODEL SOLUTION KEEPS THE FRONT NORTHEAST OF THE CWA...THEREFORE I KEPT POPS AT 14 PERCENT MONDAY NIGHT AND TUESDAY. HIGHS SUNDAY THROUGH TUESDAY WILL ONLY REACH THE LOWER TO MID 90S...SINCE THE 5H RIDGE AXIS WILL SHIFT FARTHER WEST. HIGH MAY BE A BIT COOLER ON SUNDAY AND MONDAY IF THE ECMWF SOLUTION WERE TO VERIFY BRING THE SFC COLD FRONT SOUTHWEST ACROSS THE CWA. GARGAN && .AVIATION... FEW WEAK ELEVATED SHOWERS AND TSTMS THIS MORNING HAVE MOSTLY DISSIPATED. EASTERLY WINDS IN EAST CENTRAL AND NORTHEAST KS KEEPING DEWPOINTS IN THE UPPER 60S TO LOWER 70S. ATMOSPHERE DOES DESTABILIZE LATE THIS AFTERNOON/EVENING IN THE VICINITY OF A FRONTAL BOUNDARY. ISOLATED TSTMS AGAIN POSSIBLE AND HAVE KEPT VCTS IN KTOP/KFOE TAFS. FRONTAL BOUNDARY SHIFTS FARTHER SOUTH OVERNIGHT WITH CONTINUED EAST TO NORTHEAST SURFACE WINDS. VFR CONDITIONS WILL CONTINUE. STARK && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PHILLIPS/GARGAN/STARK ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 1208 PM CDT TUE JUL 22 2008 .UPDATE... UPDATED FOR 18 UTC AVIATION && .DISCUSSION... SEE PREVIOUS DISCUSSION BELOW... && .AVIATION... FEW WEAK ELEVATED SHOWERS AND TSTMS THIS MORNING HAVE MOSTLY DISSIPATED. EASTERLY WINDS IN EAST CENTRAL AND NORTHEAST KS KEEPING DEWPOINTS IN THE UPPER 60S TO LOWER 70S. ATMOSPHERE DOES DESTABILIZE LATE THIS AFTERNOON/EVENING IN THE VICINITY OF A FRONTAL BOUNDARY. ISOLATED TSTMS AGAIN POSSIBLE AND HAVE KEPT VCTS IN KTOP/KFOE TAFS. FRONTAL BOUNDARY SHIFTS FARTHER SOUTH OVERNIGHT WITH CONTINUED EAST TO NORTHEAST SURFACE WINDS. VFR CONDITIONS WILL CONTINUE. STARK && .PREV DISCUSSION... /ISSUED 350 AM CDT TUE JUL 22 2008/ DISCUSSION... 08Z WATER VAPOR SHOWS A TROUGH ALONG THE PACIFIC NORTHWEST COAST AND THE GREAT LAKES/NORTHEAST U.S. AN UPPER LEVEL RIDGE WAS CENTERED OVER THE SOUTHERN ROCKIES AND EXTENDED NORTH INTO THE CENTRAL HIGH PLAINS. A SHORTWAVE MOVING THROUGH THE UPPER MID WEST WAS ROTATING THROUGH IA WITH ANOTHER SHORTWAVE OVER MN. ELEVATED CONVECTION HAS DEVELOPED ALONG A MOISTURE AXIS BETWEEN 800 AND 700MB FROM SOUTHEAST NEB INTO NORTHERN MO. ISENTROPIC LIFT ON THE 310K SFC DEPICTED BY THE RUC SHOWS THIS NARROW CORRIDOR OF MOISTURE REMAINING JUST NORTHEAST OF BROWN COUNTY. GFS ALSO KEEPS ITS QPF JUST TO THE NORTHEAST. WITH THE RUC SHOWING SOME DRYER AIR OVER CENTRAL KS...THINK BULK OF ELEVATED CONVECTION WILL REMAIN JUST TO THE NORTHEAST OF THE FORECAST AREA WITH MOST OF THE LIFT OVERHEAD GOING INTO SATURATING PARCELS AS THEY LIFT INTO NORTHERN MO. NEVERTHELESS WILL MAINTAIN LOW POPS THROUGH 12Z. AFTER 12Z...LEFT LOOKS TO DIMINISH AND PRECIP MAY BE PUSHING OFF TO THE EAST. FOR THE REST OF TODAY THROUGH WEDNESDAY...THE ATMOSPHERE WILL BE CHARACTERIZED AS CONDITIONALLY UNSTABLE WITH NO REAL FORCING TO SPEAK OF AS THE UPPER RIDGE REMAINS JUST TO THE WEST OVER THE HIGH PLAINS. WHILE MID LEVEL TEMPS ARE NOT OVERWHELMING IN TERMS OF A CAP...WEAK LOW LEVEL CAA WITH THE EASTERLY WIND WILL PREVENT THE BOUNDARY LAYER FROM MIXING AS DEEP AS IT HAS THE PAST COUPLE DAYS OVER EASTERN KS WHERE LOW LEVEL MOISTURE IS EXPECTED TO POOL. SO THE QUESTION IS WHETHER THERE WILL BE ENOUGH HEATING AND LOW LEVEL CONVERGENCE ALONG THE FRONT TO ALLOW A STORM TO DEVELOP. IN GENERAL DO NOT FEEL CONFIDENT TO REMOVE POPS GIVEN THE AMOUNT OF INSTABILITY THERE COULD BE WITH DEWPOINTS POOLING AROUND 70 DEGREES. KEPT SOME CHANCE POPS THIS AFTERNOON OVER EAST CENTRAL KS WHERE THE BOUNDARY AND GREATEST INSTABILITY SHOULD BE CO-LOCATED. FOR TONIGHT THROUGH WEDNESDAY NIGHT FELT CHANCE POPS WERE A LITTLE OVERDONE GIVEN LITTLE IF ANY FORCING PROGGED BY THE MODELS. KEPT SLIGHT CHANCE POPS FOR THE POSSIBILITY OF ISOLATED CONVECTION TO FORM. BY WEDNESDAY...THE BOUNDARY SHOULD BEGIN TO WASH OUT AND PRECIP CHANCES SHOULD SHIFT BACK NORTH. HIGHS TODAY AND WEDNESDAY ACROSS EASTERN KS SHOULD BE COOLER GIVEN THE DIMINISHED MIXING AND THE EASTERLY WINDS. PARTS OF NORTH CENTRAL KS AHEAD OF THE WEAK BOUNDARY SHOULD STILL REACH THE UPPER 90S. FORECAST REMAINS IN TACT FOR THURSDAY THROUGH MONDAY. THE GFS LOOKS TO SUFFER FROM FEEDBACK ISSUES ON THURSDAY WITH A CONVECTIVELY INDUCED VORT MAX PROPAGATING ACROSS NORTHEAST KS DURING THE DAY. HAVE LITTLE CONFIDENCE IN THIS SO MAINTAINED SLIGHT CHANCE POPS. UNCERTAINTY IN SFC FEATURES FOR THE WEEKEND AND BEYOND PRECLUDED ANY CHANGES. WOLTERS && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 1039 AM CDT TUE JUL 22 2008 .UPDATE... WIDELY SCATTERED CONVECTION CONTINUES TO WANE AS BETTER ISENTROPIC LIFT IN THE 310K LAYER MOVES TO THE EAST INTO MISSOURI. THE WEAK CONVECTION NEAR COUNCIL GROVE IS STILL SOMEWHAT ROOTED ON THE TAIL END OF THE SHORTWAVE CURRENTLY MOVING THROUGH CENTRAL MO. SHORT TERM MODELS STILL SHOWS LOTS OF ML CAPE (3000-3500 J/KG) ACROSS ERN KS THIS AFTERNOON...WITH FORECAST SOUNDINGS SHOWING SOME UNSTABLE AIR BELOW 700H. BUT WARMER AIR ALOFT WILL PROBABLY KEEP CONVECTION FROM REGENERATING OR BECOMING WIDESPREAD AS IT MOVES EAST INTO THIS SURFACE BASED INSTABILITY. COULD STILL SEE A FEW ISOLATED SHRA/TSRA NEAR THE ALLEN AND WILSON CO LINE....SO WILL KEEP A LOW POP FOR THIS INTO THE AFTERNOON HOURS. WILL ALSO LEAVE A LOW POP INTO SOUTHEAST KS FOR THE EVENING HOURS AS WELL...AS BACKDOOR SURFACE BOUNDARY DRIFTS SOUTHWEST INTO THIS AREA. STILL SOME CONCERN ABOUT MID LEVEL CAP KEEPING CONVECTION FROM DEVELOPING SO WILL KEEP POP IN THE SLIGHT CATEGORY FOR NOW. THE MAIN CONCERN ELSEWHERE WILL BE HOT TEMPS. SOME AREAS WILL APPROACH THE CENTURY MARK ESPECIALLY ACROSS CENTRAL KS WHERE SOMEWHAT DRIER AIR WILL LEAD TO A NICE DIURNAL TEMP SWING WITH SOME HEAT INDICES APPROACHING 105. .AVIATION... FOR THE 18Z TAF SUITE. MAINLY VFR CONDITIONS EXPECTED FOR MOST TAF SITES...WITH THE MAIN CONCERN BEING THIS AFTERNOON/EVENING NEAR THE KCNU TAF SITE. WILL KEEP SOME MID LEVEL CEILING MENTIONED IN THIS AREA...AS WANING CONVECTION STAYS JUST TO THE NORTH OF THIS AREA. WILL NOT INCLUDE A VCTS MENTION EITHER FOR NEAR KCNU...BUT COULD SEE THIS ADDED LATER. KETCHAM && .PREV DISCUSSION... /ISSUED 700 AM CDT TUE JUL 22 2008/ UPDATE... AVIATION... 12Z TAF ISSUANCE: SCT ACCAS CONTS TO DEVELOP OVER C & ERN KS EARLY THIS MORNING IN REGION OF ISENTROPIC ASCENT IN 305-310K LAYER JUXTAPOSED WITH NEARLY STATIONARY 925-MB FRONT DRAPED IN NEARLY W-E MANNER OVER THESE AREAS. SHRA/TSRA HAVE YET TO DEVELOP BUT CONTINUE TO MONITOR CLOSELY. WITH STATIONARY FRONT LURKING ABOUT SCT-ISOLATED TSRA POSSIBLE THIS AFTERNOON & EVENING OVER PRIMARILY NE KS WHERE CLOSER TO TRACK OF SECONDARY MID-LEVEL SHORTWAVE SWINGING ALMOST DUE S OVER MS VALLEY. WITH EXPECTED COVERAGE OVER C KS TO BE MORE ISOLATED IN NATURE...HAVE OPTED TO KEEP "VCTS" OUT OF KSLN FOR TIME BEING. PREV DISCUSSION... /ISSUED 454 AM CDT TUE JUL 22 2008/ UPDATE... LATEST IR LOOP/FOG IMAGERY CONTINUES TO SHOW THE ALTOCUMULUS CASTELLANEOUS INCREASING IN COVERAGE IN AREAS BETWEEN SALINA AND CONCORDIA. THIS IS IN ASSOCIATION WITH AN AREA OF ISENTROPIC ASCENT/MOISTURE TRANSPORT AROUND 310K MOVING THROUGH WESTERN KANSAS...ACCORDING TO THE LATEST RUC. LATEST LAPS DATA IS SHOWING 0-3KM MOST UNSTABLE CAPES AROUND 1200 J/KG. THIS COULD LEAD TO THE DEVELOPMENT OF A FEW THUNDERSTORMS ACROSS AREAS MAINLY NORTH OF INTERSTATE 70 BEFORE 12Z. WE MAY EXTEND THE POPS BEYOND 12Z...BUT WE WILL MONITOR FOR A LITTLE LONGER BEFORE MAKING THAT DECISION. COX PREV DISCUSSION... /ISSUED 258 AM CDT TUE JUL 22 2008/ DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST PACKAGE WILL BE THE HEAT AND HOW LONG IT LAST. THE OTHER CONCERN IS THE THUNDERSTORM CHANCES BEGINNING THIS AFTERNOON AND CONTINUING THROUGH WEDNESDAY. TODAY AND TONIGHT: LATEST IR LOOP IS SHOWING ANOTHER ATMOSPHERIC FIREWORKS SHOW MOVING THROUGH THE MISSISSIPPI VALLEY TONIGHT. THIS COMPLEX OF STORMS IS ASSOCIATED WITH A FAIRLY STRONG SHORTWAVE MOVING THROUGH EASTERN IOWA. AS THIS SHORTWAVE CONTINUES TO TRACK EAST...IT WILL CAUSE THE FRONTAL BOUNDARY CURRENTLY NEAR THE KANSAS AND NEBRASKA BORDER TO PUSH SLOWLY SOUTH TODAY. THIS BOUNDARY COULD SET OFF A FEW PULSE SEVERE THUNDERSTORMS MAINLY IN NORTHEAST KANSAS THIS AFTERNOON DUE TO MIXED LAYER CAPES AROUND 2500-3000J/KG AND WEAK SHEAR. THESE STORMS WILL ALSO CREATE SEVERAL COLD POOL BOUNDARIES WHICH WILL ACT AS A FOCUS MECHANISM FOR MORE ACTIVITY EARLY THIS EVENING. THE MODELS ARE SHOWING A FAIRLY WEAK LOW LEVEL JET IN SOUTHEAST KANSAS...SO WE WOULD EXPECT MOST OF THE ACTIVITY TO DRIVE ALONG THE MEAN MID LEVEL FLOW INTO MISSOURI. HOWEVER...A FEW OF THESE STORMS COULD CLIP THE NORTHEAST PORTION OF OUR FORECAST AREA THIS LATE THIS AFTERNOON AND TONIGHT. THEREFORE...WE HAVE KEPT A CHANCE OF THUNDERSTORMS IN THE PICTURE MAINLY EAST OF A SALINA TO EL DORADO TO INDEPENDENCE LINE. TEMPERATURES THIS AFTERNOON AND TONIGHT WILL BE FAIRLY SIMILAR TO YESTERDAY AND THIS MORNING. WEDNESDAY: THE MODELS ARE SHOWING THE FRONTAL BOUNDARY BEGINNING TO WASH OUT AS THE UPPER LEVEL RIDGE BEGINS TO FLATTEN OVER THE PLAINS. HOWEVER...THE ECMWF/GFS AND UKMET ARE SHOWING AN INSTABILITY AXIS EXTENDING FROM SALINA TO SOUTHEAST KANSAS. WE ARE NOT EXPECTING MUCH ACTIVITY IN THIS INSTABILITY AXIS DUE TO LIMITED LOW LEVEL FORCING...BUT WE CANNOT RULE OUT AN ISOLATED STRONG STORM OR TWO. THEREFORE...WE KEPT A SLIGHT CHANCE OF THUNDERSTORMS IN THE PICTURE. WEDNESDAY NIGHT-SATURDAY: THE HOT AND DRY PATTERN WILL PERSIST INTO THE WEEKEND WITH AFTERNOON TEMPERATURES STAYING CLOSE TO THE CENTURY MARK. WE DID RAISE TEMPERATURES AND LOWERED DEWPOINTS A FEW NOTCHES IN THIS TIMEFRAME. COX AVIATION... 06Z TAF UPDATE...VFR CONDITIONS ARE EXPECTED TO PREVAIL FOR TONIGHT INTO TOMORROW FOR ALL TERMINALS...HOWEVER A FRONTAL BOUNDARY WILL BEGIN TO SAG SLOWLY SOUTHWARD ACROSS KANSAS FOR TUESDAY AFTERNOON. WIDELY SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP NEAR THE FRONT FOR THE MID TO LATE AFTERNOON HOURS. JAKUB && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 99 72 99 72 / 10 10 0 10 HUTCHINSON 99 71 100 72 / 10 10 10 10 NEWTON 98 71 98 72 / 10 20 10 10 ELDORADO 97 71 98 72 / 10 20 10 10 WINFIELD-KWLD 98 73 99 72 / 10 10 0 10 RUSSELL 100 68 99 69 / 10 10 10 10 GREAT BEND 99 68 100 69 / 10 10 0 10 SALINA 98 70 99 71 / 10 20 20 10 MCPHERSON 99 70 98 71 / 10 10 10 10 COFFEYVILLE 98 73 95 72 / 10 20 20 10 CHANUTE 98 71 95 72 / 10 20 20 10 IOLA 98 71 95 72 / 20 20 20 10 PARSONS-KPPF 98 72 95 72 / 10 20 20 10 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 723 AM CDT TUE JUL 22 2008 .UPDATE... UPDATED FOR 12 UTC AVIATION && .DISCUSSION... SEE PREVIOUS DISCUSSION BELOW... && .AVIATION... AN AREA OF ACCAS AT 12 KFT HAS PERSISTED FOR MOST OF THE MORNING HOURS. MOST AREAS SHOULD REMAIN DRY AND VFR CONDITIONS WITH A FEW ISOLATED SHOWERS POSSIBLE THIS MORNING. OTHERWISE...A FEW THUNDERSTORMS MAY DEVELOP LATE THIS AFTERNOON INTO TONIGHT IN THE VICINITY OF A FRONTAL BOUNDARY. FOE/TOP LOOK TO HAVE A BETTER SHOT AT SEEING AT LEAST VCTS...WITH MODELS SUGGESTING THE HIGHEST PROBABILITY ACROSS FAR EASTERN KANSAS. EASTERLY SFC WIND WILL BE THE DOMINANT VECTOR DURING THE TAF FORECAST PERIOD WITH SPEEDS UNDER 12 KTS. BLAIR && .PREV DISCUSSION... /ISSUED 350 AM CDT TUE JUL 22 2008/ DISCUSSION... 08Z WATER VAPOR SHOWS A TROUGH ALONG THE PACIFIC NORTHWEST COAST AND THE GREAT LAKES/NORTHEAST U.S. AN UPPER LEVEL RIDGE WAS CENTERED OVER THE SOUTHERN ROCKIES AND EXTENDED NORTH INTO THE CENTRAL HIGH PLAINS. A SHORTWAVE MOVING THROUGH THE UPPER MID WEST WAS ROTATING THROUGH IA WITH ANOTHER SHORTWAVE OVER MN. ELEVATED CONVECTION HAS DEVELOPED ALONG A MOISTURE AXIS BETWEEN 800 AND 700MB FROM SOUTHEAST NEB INTO NORTHERN MO. ISENTROPIC LIFT ON THE 310K SFC DEPICTED BY THE RUC SHOWS THIS NARROW CORRIDOR OF MOISTURE REMAINING JUST NORTHEAST OF BROWN COUNTY. GFS ALSO KEEPS ITS QPF JUST TO THE NORTHEAST. WITH THE RUC SHOWING SOME DRYER AIR OVER CENTRAL KS...THINK BULK OF ELEVATED CONVECTION WILL REMAIN JUST TO THE NORTHEAST OF THE FORECAST AREA WITH MOST OF THE LIFT OVERHEAD GOING INTO SATURATING PARCELS AS THEY LIFT INTO NORTHERN MO. NEVERTHELESS WILL MAINTAIN LOW POPS THROUGH 12Z. AFTER 12Z...LEFT LOOKS TO DIMINISH AND PRECIP MAY BE PUSHING OFF TO THE EAST. FOR THE REST OF TODAY THROUGH WEDNESDAY...THE ATMOSPHERE WILL BE CHARACTERIZED AS CONDITIONALLY UNSTABLE WITH NO REAL FORCING TO SPEAK OF AS THE UPPER RIDGE REMAINS JUST TO THE WEST OVER THE HIGH PLAINS. WHILE MID LEVEL TEMPS ARE NOT OVERWHELMING IN TERMS OF A CAP...WEAK LOW LEVEL CAA WITH THE EASTERLY WIND WILL PREVENT THE BOUNDARY LAYER FROM MIXING AS DEEP AS IT HAS THE PAST COUPLE DAYS OVER EASTERN KS WHERE LOW LEVEL MOISTURE IS EXPECTED TO POOL. SO THE QUESTION IS WHETHER THERE WILL BE ENOUGH HEATING AND LOW LEVEL CONVERGENCE ALONG THE FRONT TO ALLOW A STORM TO DEVELOP. IN GENERAL DO NOT FEEL CONFIDENT TO REMOVE POPS GIVEN THE AMOUNT OF INSTABILITY THERE COULD BE WITH DEWPOINTS POOLING AROUND 70 DEGREES. KEPT SOME CHANCE POPS THIS AFTERNOON OVER EAST CENTRAL KS WHERE THE BOUNDARY AND GREATEST INSTABILITY SHOULD BE CO-LOCATED. FOR TONIGHT THROUGH WEDNESDAY NIGHT FELT CHANCE POPS WERE A LITTLE OVERDONE GIVEN LITTLE IF ANY FORCING PROGGED BY THE MODELS. KEPT SLIGHT CHANCE POPS FOR THE POSSIBILITY OF ISOLATED CONVECTION TO FORM. BY WEDNESDAY...THE BOUNDARY SHOULD BEGIN TO WASH OUT AND PRECIP CHANCES SHOULD SHIFT BACK NORTH. HIGHS TODAY AND WEDNESDAY ACROSS EASTERN KS SHOULD BE COOLER GIVEN THE DIMINISHED MIXING AND THE EASTERLY WINDS. PARTS OF NORTH CENTRAL KS AHEAD OF THE WEAK BOUNDARY SHOULD STILL REACH THE UPPER 90S. FORECAST REMAINS IN TACT FOR THURSDAY THROUGH MONDAY. THE GFS LOOKS TO SUFFER FROM FEEDBACK ISSUES ON THURSDAY WITH A CONVECTIVELY INDUCED VORT MAX PROPAGATING ACROSS NORTHEAST KS DURING THE DAY. HAVE LITTLE CONFIDENCE IN THIS SO MAINTAINED SLIGHT CHANCE POPS. UNCERTAINTY IN SFC FEATURES FOR THE WEEKEND AND BEYOND PRECLUDED ANY CHANGES. WOLTERS && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 700 AM CDT TUE JUL 22 2008 .UPDATE... .AVIATION... 12Z TAF ISSUANCE: SCT ACCAS CONTS TO DEVELOP OVER C & ERN KS EARLY THIS MORNING IN REGION OF ISENTROPIC ASCENT IN 305-310K LAYER JUXTAPOSED WITH NEARLY STATIONARY 925-MB FRONT DRAPED IN NEARLY W-E MANNER OVER THESE AREAS. SHRA/TSRA HAVE YET TO DEVELOP BUT CONTINUE TO MONITOR CLOSELY. WITH STATIONARY FRONT LURKING ABOUT SCT-ISOLATED TSRA POSSIBLE THIS AFTERNOON & EVENING OVER PRIMARILY NE KS WHERE CLOSER TO TRACK OF SECONDARY MID-LEVEL SHORTWAVE SWINGING ALMOST DUE S OVER MS VALLEY. WITH EXPECTED COVERAGE OVER C KS TO BE MORE ISOLATED IN NATURE...HAVE OPTED TO KEEP "VCTS" OUT OF KSLN FOR TIME BEING. && .PREV DISCUSSION... /ISSUED 454 AM CDT TUE JUL 22 2008/ UPDATE... LATEST IR LOOP/FOG IMAGERY CONTINUES TO SHOW THE ALTOCUMULUS CASTELLANEOUS INCREASING IN COVERAGE IN AREAS BETWEEN SALINA AND CONCORDIA. THIS IS IN ASSOCIATION WITH AN AREA OF ISENTROPIC ASCENT/MOISTURE TRANSPORT AROUND 310K MOVING THROUGH WESTERN KANSAS...ACCORDING TO THE LATEST RUC. LATEST LAPS DATA IS SHOWING 0-3KM MOST UNSTABLE CAPES AROUND 1200 J/KG. THIS COULD LEAD TO THE DEVELOPMENT OF A FEW THUNDERSTORMS ACROSS AREAS MAINLY NORTH OF INTERSTATE 70 BEFORE 12Z. WE MAY EXTEND THE POPS BEYOND 12Z...BUT WE WILL MONITOR FOR A LITTLE LONGER BEFORE MAKING THAT DECISION. COX PREV DISCUSSION... /ISSUED 258 AM CDT TUE JUL 22 2008/ DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST PACKAGE WILL BE THE HEAT AND HOW LONG IT LAST. THE OTHER CONCERN IS THE THUNDERSTORM CHANCES BEGINNING THIS AFTERNOON AND CONTINUING THROUGH WEDNESDAY. TODAY AND TONIGHT: LATEST IR LOOP IS SHOWING ANOTHER ATMOSPHERIC FIREWORKS SHOW MOVING THROUGH THE MISSISSIPPI VALLEY TONIGHT. THIS COMPLEX OF STORMS IS ASSOCIATED WITH A FAIRLY STRONG SHORTWAVE MOVING THROUGH EASTERN IOWA. AS THIS SHORTWAVE CONTINUES TO TRACK EAST...IT WILL CAUSE THE FRONTAL BOUNDARY CURRENTLY NEAR THE KANSAS AND NEBRASKA BORDER TO PUSH SLOWLY SOUTH TODAY. THIS BOUNDARY COULD SET OFF A FEW PULSE SEVERE THUNDERSTORMS MAINLY IN NORTHEAST KANSAS THIS AFTERNOON DUE TO MIXED LAYER CAPES AROUND 2500-3000J/KG AND WEAK SHEAR. THESE STORMS WILL ALSO CREATE SEVERAL COLD POOL BOUNDARIES WHICH WILL ACT AS A FOCUS MECHANISM FOR MORE ACTIVITY EARLY THIS EVENING. THE MODELS ARE SHOWING A FAIRLY WEAK LOW LEVEL JET IN SOUTHEAST KANSAS...SO WE WOULD EXPECT MOST OF THE ACTIVITY TO DRIVE ALONG THE MEAN MID LEVEL FLOW INTO MISSOURI. HOWEVER...A FEW OF THESE STORMS COULD CLIP THE NORTHEAST PORTION OF OUR FORECAST AREA THIS LATE THIS AFTERNOON AND TONIGHT. THEREFORE...WE HAVE KEPT A CHANCE OF THUNDERSTORMS IN THE PICTURE MAINLY EAST OF A SALINA TO EL DORADO TO INDEPENDENCE LINE. TEMPERATURES THIS AFTERNOON AND TONIGHT WILL BE FAIRLY SIMILAR TO YESTERDAY AND THIS MORNING. WEDNESDAY: THE MODELS ARE SHOWING THE FRONTAL BOUNDARY BEGINNING TO WASH OUT AS THE UPPER LEVEL RIDGE BEGINS TO FLATTEN OVER THE PLAINS. HOWEVER...THE ECMWF/GFS AND UKMET ARE SHOWING AN INSTABILITY AXIS EXTENDING FROM SALINA TO SOUTHEAST KANSAS. WE ARE NOT EXPECTING MUCH ACTIVITY IN THIS INSTABILITY AXIS DUE TO LIMITED LOW LEVEL FORCING...BUT WE CANNOT RULE OUT AN ISOLATED STRONG STORM OR TWO. THEREFORE...WE KEPT A SLIGHT CHANCE OF THUNDERSTORMS IN THE PICTURE. WEDNESDAY NIGHT-SATURDAY: THE HOT AND DRY PATTERN WILL PERSIST INTO THE WEEKEND WITH AFTERNOON TEMPERATURES STAYING CLOSE TO THE CENTURY MARK. WE DID RAISE TEMPERATURES AND LOWERED DEWPOINTS A FEW NOTCHES IN THIS TIMEFRAME. COX AVIATION... 06Z TAF UPDATE...VFR CONDITIONS ARE EXPECTED TO PREVAIL FOR TONIGHT INTO TOMORROW FOR ALL TERMINALS...HOWEVER A FRONTAL BOUNDARY WILL BEGIN TO SAG SLOWLY SOUTHWARD ACROSS KANSAS FOR TUESDAY AFTERNOON. WIDELY SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP NEAR THE FRONT FOR THE MID TO LATE AFTERNOON HOURS. JAKUB && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 99 72 99 72 / 10 10 0 10 HUTCHINSON 99 71 100 72 / 10 10 10 10 NEWTON 98 71 98 72 / 10 20 10 10 ELDORADO 97 71 98 72 / 10 20 10 10 WINFIELD-KWLD 98 73 99 72 / 10 10 0 10 RUSSELL 100 68 99 69 / 10 10 10 10 GREAT BEND 99 68 100 69 / 10 10 0 10 SALINA 98 70 99 71 / 20 20 20 10 MCPHERSON 99 70 98 71 / 10 10 10 10 COFFEYVILLE 98 73 95 72 / 10 20 20 10 CHANUTE 98 71 95 72 / 10 20 20 10 IOLA 98 71 95 72 / 20 20 20 10 PARSONS-KPPF 98 72 95 72 / 10 20 20 10 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 454 AM CDT TUE JUL 22 2008 .UPDATE... LATEST IR LOOP/FOG IMAGERY CONTINUES TO SHOW THE ALTOCUMULUS CASTELLANEOUS INCREASING IN COVERAGE IN AREAS BETWEEN SALINA AND CONCORDIA. THIS IS IN ASSOCIATION WITH AN AREA OF ISENTROPIC ASCENT/MOISTURE TRANSPORT AROUND 310K MOVING THROUGH WESTERN KANSAS...ACCORDING TO THE LATEST RUC. LATEST LAPS DATA IS SHOWING 0-3KM MOST UNSTABLE CAPES AROUND 1200 J/KG. THIS COULD LEAD TO THE DEVELOPMENT OF A FEW THUNDERSTORMS ACROSS AREAS MAINLY NORTH OF INTERSTATE 70 BEFORE 12Z. WE MAY EXTEND THE POPS BEYOND 12Z...BUT WE WILL MONITOR FOR A LITTLE LONGER BEFORE MAKING THAT DECISION. COX && .PREV DISCUSSION... /ISSUED 258 AM CDT TUE JUL 22 2008/ DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST PACKAGE WILL BE THE HEAT AND HOW LONG IT LAST. THE OTHER CONCERN IS THE THUNDERSTORM CHANCES BEGINNING THIS AFTERNOON AND CONTINUING THROUGH WEDNESDAY. TODAY AND TONIGHT: LATEST IR LOOP IS SHOWING ANOTHER ATMOSPHERIC FIREWORKS SHOW MOVING THROUGH THE MISSISSIPPI VALLEY TONIGHT. THIS COMPLEX OF STORMS IS ASSOCIATED WITH A FAIRLY STRONG SHORTWAVE MOVING THROUGH EASTERN IOWA. AS THIS SHORTWAVE CONTINUES TO TRACK EAST...IT WILL CAUSE THE FRONTAL BOUNDARY CURRENTLY NEAR THE KANSAS AND NEBRASKA BORDER TO PUSH SLOWLY SOUTH TODAY. THIS BOUNDARY COULD SET OFF A FEW PULSE SEVERE THUNDERSTORMS MAINLY IN NORTHEAST KANSAS THIS AFTERNOON DUE TO MIXED LAYER CAPES AROUND 2500-3000J/KG AND WEAK SHEAR. THESE STORMS WILL ALSO CREATE SEVERAL COLD POOL BOUNDARIES WHICH WILL ACT AS A FOCUS MECHANISM FOR MORE ACTIVITY EARLY THIS EVENING. THE MODELS ARE SHOWING A FAIRLY WEAK LOW LEVEL JET IN SOUTHEAST KANSAS...SO WE WOULD EXPECT MOST OF THE ACTIVITY TO DRIVE ALONG THE MEAN MID LEVEL FLOW INTO MISSOURI. HOWEVER...A FEW OF THESE STORMS COULD CLIP THE NORTHEAST PORTION OF OUR FORECAST AREA THIS LATE THIS AFTERNOON AND TONIGHT. THEREFORE...WE HAVE KEPT A CHANCE OF THUNDERSTORMS IN THE PICTURE MAINLY EAST OF A SALINA TO EL DORADO TO INDEPENDENCE LINE. TEMPERATURES THIS AFTERNOON AND TONIGHT WILL BE FAIRLY SIMILAR TO YESTERDAY AND THIS MORNING. WEDNESDAY: THE MODELS ARE SHOWING THE FRONTAL BOUNDARY BEGINNING TO WASH OUT AS THE UPPER LEVEL RIDGE BEGINS TO FLATTEN OVER THE PLAINS. HOWEVER...THE ECMWF/GFS AND UKMET ARE SHOWING AN INSTABILITY AXIS EXTENDING FROM SALINA TO SOUTHEAST KANSAS. WE ARE NOT EXPECTING MUCH ACTIVITY IN THIS INSTABILITY AXIS DUE TO LIMITED LOW LEVEL FORCING...BUT WE CANNOT RULE OUT AN ISOLATED STRONG STORM OR TWO. THEREFORE...WE KEPT A SLIGHT CHANCE OF THUNDERSTORMS IN THE PICTURE. WEDNESDAY NIGHT-SATURDAY: THE HOT AND DRY PATTERN WILL PERSIST INTO THE WEEKEND WITH AFTERNOON TEMPERATURES STAYING CLOSE TO THE CENTURY MARK. WE DID RAISE TEMPERATURES AND LOWERED DEWPOINTS A FEW NOTCHES IN THIS TIMEFRAME. COX AVIATION... 06Z TAF UPDATE...VFR CONDITIONS ARE EXPECTED TO PREVAIL FOR TONIGHT INTO TOMORROW FOR ALL TERMINALS...HOWEVER A FRONTAL BOUNDARY WILL BEGIN TO SAG SLOWLY SOUTHWARD ACROSS KANSAS FOR TUESDAY AFTERNOON. WIDELY SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP NEAR THE FRONT FOR THE MID TO LATE AFTERNOON HOURS. JAKUB && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 99 72 99 72 / 10 10 0 10 HUTCHINSON 99 71 100 72 / 10 10 10 10 NEWTON 98 71 98 72 / 10 20 10 10 ELDORADO 97 71 98 72 / 10 20 10 10 WINFIELD-KWLD 98 73 99 72 / 10 10 0 10 RUSSELL 100 68 99 69 / 10 10 10 10 GREAT BEND 99 68 100 69 / 10 10 0 10 SALINA 98 70 99 71 / 20 20 20 10 MCPHERSON 99 70 98 71 / 10 10 10 10 COFFEYVILLE 98 73 95 72 / 10 20 20 10 CHANUTE 98 71 95 72 / 10 20 20 10 IOLA 98 71 95 72 / 20 20 20 10 PARSONS-KPPF 98 72 95 72 / 10 20 20 10 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 350 AM CDT TUE JUL 22 2008 .DISCUSSION... 08Z WATER VAPOR SHOWS A TROUGH ALONG THE PACIFIC NORTHWEST COAST AND THE GREAT LAKES/NORTHEAST U.S. AN UPPER LEVEL RIDGE WAS CENTERED OVER THE SOUTHERN ROCKIES AND EXTENDED NORTH INTO THE CENTRAL HIGH PLAINS. A SHORTWAVE MOVING THROUGH THE UPPER MID WEST WAS ROTATING THROUGH IA WITH ANOTHER SHORTWAVE OVER MN. ELEVATED CONVECTION HAS DEVELOPED ALONG A MOISTURE AXIS BETWEEN 800 AND 700MB FROM SOUTHEAST NEB INTO NORTHERN MO. ISENTROPIC LIFT ON THE 310K SFC DEPICTED BY THE RUC SHOWS THIS NARROW CORRIDOR OF MOISTURE REMAINING JUST NORTHEAST OF BROWN COUNTY. GFS ALSO KEEPS ITS QPF JUST TO THE NORTHEAST. WITH THE RUC SHOWING SOME DRYER AIR OVER CENTRAL KS...THINK BULK OF ELEVATED CONVECTION WILL REMAIN JUST TO THE NORTHEAST OF THE FORECAST AREA WITH MOST OF THE LIFT OVERHEAD GOING INTO SATURATING PARCELS AS THEY LIFT INTO NORTHERN MO. NEVERTHELESS WILL MAINTAIN LOW POPS THROUGH 12Z. AFTER 12Z...LEFT LOOKS TO DIMINISH AND PRECIP MAY BE PUSHING OFF TO THE EAST. FOR THE REST OF TODAY THROUGH WEDNESDAY...THE ATMOSPHERE WILL BE CHARACTERIZED AS CONDITIONALLY UNSTABLE WITH NO REAL FORCING TO SPEAK OF AS THE UPPER RIDGE REMAINS JUST TO THE WEST OVER THE HIGH PLAINS. WHILE MID LEVEL TEMPS ARE NOT OVERWHELMING IN TERMS OF A CAP...WEAK LOW LEVEL CAA WITH THE EASTERLY WIND WILL PREVENT THE BOUNDARY LAYER FROM MIXING AS DEEP AS IT HAS THE PAST COUPLE DAYS OVER EASTERN KS WHERE LOW LEVEL MOISTURE IS EXPECTED TO POOL. SO THE QUESTION IS WHETHER THERE WILL BE ENOUGH HEATING AND LOW LEVEL CONVERGENCE ALONG THE FRONT TO ALLOW A STORM TO DEVELOP. IN GENERAL DO NOT FEEL CONFIDENT TO REMOVE POPS GIVEN THE AMOUNT OF INSTABILITY THERE COULD BE WITH DEWPOINTS POOLING AROUND 70 DEGREES. KEPT SOME CHANCE POPS THIS AFTERNOON OVER EAST CENTRAL KS WHERE THE BOUNDARY AND GREATEST INSTABILITY SHOULD BE CO-LOCATED. FOR TONIGHT THROUGH WEDNESDAY NIGHT FELT CHANCE POPS WERE A LITTLE OVERDONE GIVEN LITTLE IF ANY FORCING PROGGED BY THE MODELS. KEPT SLIGHT CHANCE POPS FOR THE POSSIBILITY OF ISOLATED CONVECTION TO FORM. BY WEDNESDAY...THE BOUNDARY SHOULD BEGIN TO WASH OUT AND PRECIP CHANCES SHOULD SHIFT BACK NORTH. HIGHS TODAY AND WEDNESDAY ACROSS EASTERN KS SHOULD BE COOLER GIVEN THE DIMINISHED MIXING AND THE EASTERLY WINDS. PARTS OF NORTH CENTRAL KS AHEAD OF THE WEAK BOUNDARY SHOULD STILL REACH THE UPPER 90S. FORECAST REMAINS IN TACT FOR THURSDAY THROUGH MONDAY. THE GFS LOOKS TO SUFFER FROM FEEDBACK ISSUES ON THURSDAY WITH A CONVECTIVELY INDUCED VORT MAX PROPAGATING ACROSS NORTHEAST KS DURING THE DAY. HAVE LITTLE CONFIDENCE IN THIS SO MAINTAINED SLIGHT CHANCE POPS. UNCERTAINTY IN SFC FEATURES FOR THE WEEKEND AND BEYOND PRECLUDED ANY CHANGES. WOLTERS && .AVIATION... OUTFLOW BOUNDARY NEARING THE TAF SITES LATE THIS EVENING BUT CONVECTION HAS PUSHED TO THE EAST AND CHANCES FOR ADDITIONAL DEVELOPMENT IN THE LOCAL AREA SEEM LOW GIVEN MEAGER 850MB MOISTURE PER 00Z UPPER AIR DATA. MAY SEE SOME LINGERING MID CLOUD THROUGH MUCH OF THIS CYCLE WITH SOME CHANCE FOR ADDITIONAL CONVECTION DURING AFTERNOON/EVENING HOURS THURSDAY WITH FRONT/OUTFLOW IN THE VICINITY...BUT CHANCES APPEAR TOO LOW FOR A MENTION AT THIS TIME. 65 && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 1230 AM MDT TUE JUL 22 2008 .DISCUSSION... 1230 AM MDT TUE JUL 22 2008 THE SUBTROPICAL RIDGE IS PROGGED TO BREAK DOWN OVER MUCH OF THE NORTHERN PLAINS STATES ON WEDNESDAY AS A SHORTWAVE TROUGH OVER NORTHERN CALIFORNIA TRANSLATES EAST/NORTHEAST INTO THE NORTHERN ROCKIES/NORTHERN PLAINS NEAR THE CANADIAN BORDER. FURTHER SOUTH...LOW LEVEL MOISTURE HAS POOLED ALONG A SLOW MOVING COLD FRONT OVER PORTIONS OF THE CENTRAL PLAINS ALLOWING DEWPOINT TEMPERATURES TO RISE INTO THE MID 70S ACROSS SOUTH CENTRAL NEBRASKA. AS THIS FRONT BACKS SLOWLY INTO THE AREA THIS MORNING...EXPECT FOG STRATUS TO EXPAND IN COVERAGE. THE PREVIOUS FORECAST CAPTURED THIS SCENARIO WITH ONLY SUBTLE CHANGES PLANNED. LOW LEVEL WIND TRAJECTORIES SUPPORT LOWERING MAXIMUM TEMPERATURES ACROSS THE NORTHEAST ZONES WHERE A LULL IN DEEP VERTICAL MIXING IS ANTICIPATED GIVEN MOIST EASTERLY POST-FRONTAL REGIME. NAM/GFS FORECAST SOUNDINGS SUPPORT THE PREVIOUS FORECAST WITH ISOLATED THUNDERSTORMS WEIGHTED ACROSS THE NORTHEAST ZONES WHERE MLCAPE IS MAXIMIZED WITH MINIMAL CINH. WEDNESDAY-THURSDAY...THE SUBTROPICAL RIDGE CONTINUES TO SPRAWL OVER THE SOUTHERN ROCKIES WITH SIMILAR TEMPERATURES IN THE UPPER 90S/AROUND 100 EXPECTED ACROSS THE TRI-STATE AREA. THE STALLED FRONT MAY LIFT NORTHEAST OF THE AREA...BUT UNCERTAINTY REMAINS RATHER HIGH SO LEANED A LITTLE COOLER TOWARD THE KMCK AREA. INCREASING H7 TEMPERATURES SUGGEST VERY LIMITED CHANCES FOR DEEP MOIST CONVECTION AND PULLED POPS FROM PREVIOUS FORECAST ACROSS MUCH OF THE AREA WITH THE EXCEPTION BEING THE FAR NORTHWEST ZONES WHERE AN ISOLATED THUNDERSTORM MAY DRIFT ENE OFF THE FAVORED TERRAIN OUT WEST. A COLD FRONT MAY SURGE SOUTH LATE THURSDAY...HOWEVER CAPPING CONCERNS AND SOUTHERN EXTENT OF FRONT REMAIN UNCERTAIN. TRIMMED POPS TO THE FAR NORTHWEST ZONES GIVEN CAPPING CONCERNS. HIGHS ON EITHER SIZE OF 100 ARE EXPECTED ONCE AGAIN. DAYS 4 THROUGH 7...NO CHANGES. && .AVIATION... 1056 PM MDT MON JUL 21 2008 FOR THE 06Z TAFS...INITIAL PROBLEM WILL BE FOG AND STRATUS POTENTIAL FOR KMCK. NAM/RUC SIMILAR IN BRINGING IN FOG AND STRATUS AROUND 09Z. FEEL MORE CONFIDENT OF THIS HAPPENING DUE TO DEWPOINT/TEMPERATURE SPREADS VERY NARROW UPSTREAM WITH FOG ALREADY DEVELOPING. MODEL GUIDANCE SAYS THERE IS POTENTIAL TO GO TO LIFR ON THE VISIBILITY. HOWEVER...DID NOT WANT TO GO THAT FAR YET. SO KEPT MVFR VISIBILITY AND IFR CEILING. AFTER THAT...SHOULD BE VFR AT KMCK FOR THE REMAINDER OF THE PERIOD. KGLD WILL REMAIN VFR FOR THE ENTIRE PERIOD. AFTER 18Z THERE IS POTENTIAL FOR ISOLATED TSRA. AT THIS TIME NOT CONFIDENT IS LOCATION OF CONVECTION SO PUT NO MENTION OF IT IN THE TAFS WITH THE KMCK TAF HAVING THE BEST CHANCE. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 1058 PM MDT MON JUL 21 2008 .UPDATE... 824 PM MDT MON JUL 21 2008 JUST COMPLETED AN UPDATED. LOW LEVEL AIR MASS HAS BECOME CAPPED PER LAPS AND AREA SOUNDINGS. NO SIGNIFICANT LOW LEVEL JET OR LIFT AT MID LEVELS SEEN SO LOOKS LIKE NO ELEVATED TSRA DEVELOPING LATER TONIGHT. BASED ON EASTERLY WINDS AND INCREASING MOISTURE BEHIND SAGGING COLD FRONT...INSERTED PATCHY FOG INTO THE FORECAST PLUS INCREASED CLOUD COVER IN THE FAR NORTH LATER TONIGHT AND TOMORROW MORNING. ALSO ADJUST MINS UP A LITTLE BIT IN THE NORTHEAST AS WELL. TWEEKED WIND...TEMPERATURE...AND DEWPOINT GRIDS BASED ON REALITY AND LATEST GUIDANCE. BULLER && .DISCUSSION...FORECAST CONCERNS ARE TEMPERATURES AND PRECIPITATION CHANCES. SHOWERS AND THUNDERSTORMS WILL RETURN TO THE NORTHERN HALF OF THE AREA (PRIMARILY) OVER THE NEXT FEW DAYS AS A FRONTAL BOUNDARY SLOWLY SAGS SOUTH INTO THE AREA. THE FRONT COMBINED WITH INCREASING MID AND UPPER LEVEL MOISTURE VIA MONSOONAL MOISTURE AND SUFFICIENT INSTABILITY WILL BE THE DRIVING FORCE FOR THE PRECIPITATION CHANCES. STILL SOME TIMING AND POSITION DIFFERENCES WITH REGARD TO LOCATION OF THE ABOVE MENTIONED FEATURES SO FOR NOW WILL KEEP POPS ON THE SLIGHT CHANCE SIDE AND GO FROM THERE. TEMPERATURES WILL REMAIN ABOVE NORMAL WITH READINGS WELL INTO THE 90S AND PROBABLY LOW 100S FOR A FEW LOCATIONS. NAM STILL TRYING TO SUGGEST SATURATED BOUNDARY LAYER CONDITIONS ALONG THE NEARLY STATIONARY FRONTAL BOUNDARY WHILE THE GFS KEEPS IT OUT OF THE AREA. SHOULD THE NAM VERIFY STRATUS/FOG AND SOME AVIATION CONCERNS WILL DEVELOP. WILL KEEP THE FOG OUT OF THE FORECAST AGAIN TODAY UNTIL SOME CONSISTENCY DEVELOPS WITH THE PLACEMENT OF THE BOUNDARY. FRIDAY-MONDAY...LARGE AREA OF UPPER LEVEL HIGH PRESSURE WILL COVER MUCH OF THE CENTRAL AND SOUTHERN PLAINS THROUGH SATURDAY BEFORE SHIFTING WEST TOWARD THE FOUR CORNERS SUNDAY AND MONDAY AS A STATIONARY FRONTAL BOUNDARY BACKS INTO THE AREA. MONSOONAL MOISTURE AND NEAR TO ABOVE NORMAL DAYTIME TEMPERATURES WILL PROMOTE A CHANCE OF PRECIPITATION JUST ABOUT EVERY DAY. DDT && .AVIATION... 1056 PM MDT MON JUL 21 2008 FOR THE 06Z TAFS...INITIAL PROBLEM WILL BE FOG AND STRATUS POTENTIAL FOR KMCK. NAM/RUC SIMILAR IN BRINGING IN FOG AND STRATUS AROUND 09Z. FEEL MORE CONFIDENT OF THIS HAPPENING DUE TO DEWPOINT/TEMPERATURE SPREADS VERY NARROW UPSTREAM WITH FOG ALREADY DEVELOPING. MODEL GUIDANCE SAYS THERE IS POTENITAL TO GO TO LIFR ON THE VISIBILITY. HOWEVER...DID NOT WANT TO GO THAT FAR YET. SO KEPT MVFR VISIBILITY AND IFR CEILING. AFTER THAT...SHOULD BE VFR AT KMCK FOR THE REMAINDER OF THE PERIOD. KGLD WILL REMAIN VFR FOR THE ENTIRE PERIOD. AFTER 18Z THERE IS POTENTIAL FOR ISOLATED TSRA. AT THIS TIME NOT CONFIDENT IS LOCATION OF CONVECTION SO PUT NO MENTION OF IT IN THE TAFS WITH THE KMCK TAF HAVING THE BEST CHANCE. BULLER && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 548 PM MDT MON JUL 21 2008 .DISCUSSION...FORECAST CONCERNS ARE TEMPERATURES AND PRECIPITATION CHANCES. SHOWERS AND THUNDERSTORMS WILL RETURN TO THE NORTHERN HALF OF THE AREA (PRIMARILY) OVER THE NEXT FEW DAYS AS A FRONTAL BOUNDARY SLOWLY SAGS SOUTH INTO THE AREA. THE FRONT COMBINED WITH INCREASING MID AND UPPER LEVEL MOISTURE VIA MONSOONAL MOISTURE AND SUFFICIENT INSTABILITY WILL BE THE DRIVING FORCE FOR THE PRECIPITATION CHANCES. STILL SOME TIMING AND POSITION DIFFERENCES WITH REGARD TO LOCATION OF THE ABOVE MENTIONED FEATURES SO FOR NOW WILL KEEP POPS ON THE SLIGHT CHANCE SIDE AND GO FROM THERE. TEMPERATURES WILL REMAIN ABOVE NORMAL WITH READINGS WELL INTO THE 90S AND PROBABLY LOW 100S FOR A FEW LOCATIONS. NAM STILL TRYING TO SUGGEST SATURATED BOUNDARY LAYER CONDITIONS ALONG THE NEARLY STATIONARY FRONTAL BOUNDARY WHILE THE GFS KEEPS IT OUT OF THE AREA. SHOULD THE NAM VERIFY STRATUS/FOG AND SOME AVIATION CONCERNS WILL DEVELOP. WILL KEEP THE FOG OUT OF THE FORECAST AGAIN TODAY UNTIL SOME CONSISTENCY DEVELOPS WITH THE PLACEMENT OF THE BOUNDARY. FRIDAY-MONDAY...LARGE AREA OF UPPER LEVEL HIGH PRESSURE WILL COVER MUCH OF THE CENTRAL AND SOUTHERN PLAINS THROUGH SATURDAY BEFORE SHIFTING WEST TOWARD THE FOUR CORNERS SUNDAY AND MONDAY AS A STATIONARY FRONTAL BOUNDARY BACKS INTO THE AREA. MONSOONAL MOISTURE AND NEAR TO ABOVE NORMAL DAYTIME TEMPERATURES WILL PROMOTE A CHANCE OF PRECIPITATION JUST ABOUT EVERY DAY. DDT && .AVIATION... 540 PM MDT MON JUL 21 2008 FOR THE 00Z TAFS...TEDIOUS TAF FORECAST. VFR CONDITIONS EXPECTED AT KGLD THE ENTIRE TIME. AT THIS TIME...KEPT BOTH TAFS TSRA FREE SINCE LOOKS LIKE LITTLE LIFT AND DRY AIR ALOFT TO KEEP VERY MANY IF ANY TSRA FROM FORMING. KMCK HAS THE BEST CHANCE BUT ON THE VERY LOW END OF PROBABILITY. COLD FRONT JUST TO THE NORTH OF KMCK IS EXPECTED TO SLOWLY SAG SOUTH. THIS WILL MAKE FOR LIGHT AND VARIABLE WINDS. OF MORE IMPORTANCE IS IF EASTERLY WINDS BEHIND FRONT WILL PRODUCE STRATUS AND FOG AT KMCK. NAM IS THE MOST AGGRESSIVE IN DOING THIS WITH SOME SUPPORT FROM THE RUC40/13. CHOSE TO KEEP STRATUS IN BELOW 1000 FEET AND VISIBILITY AT MVFR ALTHOUGH RAISED A LITTLE. BULLER && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 1240 PM CDT MON JUL 21 2008 .UPDATE... UPDATED FOR 18 UTC AVIATION. && .DISCUSSION... SEE PREVIOUS DISCUSSION BELOW. && .AVIATION... A FEW PASSING HIGH CLOUDS WILL MOVE ACROSS THE TAF SITES TODAY. LATE THIS AFTERNOON A FEW BOUNDARY LAYER CU MAY DEVELOP WITH BASES OF 6,000 TO 8,000 FEET. AN OUTFLOW BOUNDARY/FRONT OVER NE WILL SLOWLY PUSH SOUTH BUT MAY REMAIN NORTH OF THE TAF SITES THROUGH 18Z TUE. ISOLATED THUNDERSTORMS MAY DEVELOP NORTH OF THE TAF SITES THIS EVENING BUT WILL MOST LIKELY WEAKEN AS THEY MOVE SOUTHEAST TOWARDS THE TAF SITES LATE THIS EVENING AND THROUGH THE EARLY MORNING HOURS OF TUESDAY. I PLACED IN A CB MENTION IN THE TAFS IN CASE THE ISOLATED THUNDERSTORM HOLD TOGETHER AND MOVE NEAR THE TAF SITES TONIGHT. THERE MAY BE ANOTHER CHANCE FOR ISOLATED TO SCATTERED THUNDERSTORMS AT OR AROUND THE TAF SITES TUESDAY AFTERNOON AS THE COLD FRONT PUSHES SOUTHEAST ACROSS THE TAF SITES TUESDAY AFTERNOON. && .PREV DISCUSSION... /ISSUED 709 AM CDT MON JUL 21 2008/ UPDATE... UPDATED FOR 12 UTC AVIATION DISCUSSION... SEE PREVIOUS DISCUSSION BELOW... AVIATION... CONVECTIVE COMPLEX THAT PASSED FROM NEBRASKA TO ILLINOIS LEFT BEHIND HIGH LEVEL CIRRUS ACROSS THE AREA. VERTICAL MOISTURE PROFILES STILL FAIRLY DRY WHICH SHOULD PROHIBIT CLOUDS TO DEVELOP DURING THE DAY MINUS HIGH LEVEL CLOUDINESS. SHORT DURATION OF VARIABLE WINDS THIS MORNING PER OUTFLOW BOUNDARIES TRANSITIONING TO PREVAILING SOUTHERLY WINDS FOR THE MAJORITY OF THE DAY. INCOMING FRONTAL BOUNDARY LATE TONIGHT MAY FIRE A FEW STORMS ALTHOUGH CONFIDENCE AT TAF SITES IS RATHER LOW ATTM UNTIL NEAR THE END OF THE TAF FORECAST PERIOD. BLAIR PREV DISCUSSION... /ISSUED 340 AM CDT MON JUL 21 2008/ DISCUSSION... 08Z WATER VAPOR SHOWS A CLOSED UPPER LOW OFF THE NORTHERN CA COAST WITH A COUPLE SHORTWAVES MOVING FROM THE NORTHERN PLAINS INTO THE GREAT LAKES. RIDGING BETWEEN THESE FEATURES WAS FOUND OVER THE SOUTHERN ROCKIES AND PLAINS. A SHORTWAVE MOVING ACROSS THE NORTHER PLAINS HELPED TO SPARK CONVECTION ALONG THE 850 FRONT OVER NORTHERN NEB AND INTO IA. THE OUTFLOW FROM THIS CONVECTION HAS PUSHED INTO NORTH CENTRAL KS BUT IS LOOSING STEAM AS IT MOVES SOUTH. THE 06Z RUC SHOWS THE OUTFLOW BOUNDARY WASHING OUT THIS MORNING AND LOOSING ITS IDENTITY. MEANWHILE THE GFS KEEPS THE MAIN SYNOPTIC FRONT NORTH OF THE FORECAST AREA THROUGH 00Z AND THE 06Z NAM HAS TRENDED THIS WAY AS WELL. KEPT SOME SLIGHT CHANCE POPS ACROSS THE EXTREME NORTHERN SECTIONS OF THE AREA LATE THIS AFTERNOON IN CASE THERE IS A WEAK AREA OF CONVERGENCE. OTHERWISE ANTICIPATE TODAY TO BE SIMILAR TO YESTERDAY WITH LOTS OF SUNSHINE AND HIGHS IN THE UPPER 90S. 850 TEMPS DO NOT CHANGE TO MUCH FROM YESTERDAY SO HAVE GONE WITH PERSISTENCE WITH FORECAST HIGHS TODAY. ANOTHER ROUND OF CONVECTION SHOULD DEVELOP ALONG THE BOUNDARY TONIGHT...BUT WITH THE GFS AND NAM KEEPING THE 850 BOUNDARY ACROSS CENTRAL NEB AND SOUTHERN IA HAVE ADJUSTED POPS TO DOWN PLACE CHANCES ACROSS EAST CENTRAL KS. CONTINUED WITH POPS AROUND 50 PERCENT OVER THE FAR NORTHEAST. GIVEN THE AMOUNT OF INSTABILITY PROGGED BY THE MODELS WITH SFC DEWPOINTS IN THE LOWER 70S...THE THUNDERSTORMS COULD BECOME STRONG ENOUGH OVERNIGHT FOR DAMAGING WINDS AND SOME HAIL. FOR TUESDAY THROUGH WEDNESDAY NIGHT...MODELS SHOW THE FORECAST AREA REMAINING ON THE EASTERN EDGE OF THE UPPER RIDGE WITH THE BOUNDARY OVER THE AREA AND PWS INCREASING OVER 1.5 INCHES. FORECAST SOUNDINGS CONTINUE TO INDICATE THE MID LEVELS WILL NOT TO SO WARM THAT THEY WILL CAP THE BOUNDARY LAYER WITH 700MB TEMPS AROUND 10C. BECAUSE OF THIS HAVE CARRIED CHANCE POPS ACROSS THE EASTERN HALF OF THE FORECAST AREA THROUGH THE PERIOD FOR POSSIBLE SCATTERED CONVECTION. TEMPS SHOULD NOT BE QUIET AS WARM WITH AND EASTERLY WIND AND PARTLY CLOUDY SKIES. BUT THERE COULD BE A GOOD GRADIENT IN TEMPS DEPENDING ON WHERE THE BOUNDARY SETS UP. FAR WESTERN SECTIONS OF THE FORECAST AREA MAY REMAIN IN THE UPPER 90S WITH HIGHS AROUND 90 BEHIND THE BOUNDARY. DID NOT MAKE ANY CHANGES TO THE FORECAST FOR THURSDAY AND BEYOND. BUT LATER SHIFTS WILL NEED TO WATCH THE WEEKEND AS THE GFS CONTINUES TO SHOW ANOTHER BACKDOOR FRONT MOVING THROUGH SOMETIME DURING THE WEEKEND AS SHORTWAVE ENERGY DIVES SOUTHEAST ACROSS THE UPPER MIDWEST ALONG THE BACK SIDE OF THE MEAN EAST COAST TROUGH. THERE ARE SOME TIMING ISSUES BETWEEN THE GFS AND ECMWF WITH THIS FEATURE...BUT POPS MAY NEED TO BE INSERTED BEYOND THURSDAY TO ACCOUNT FOR THIS FEATURE WOLTERS && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ GARGAN ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 340 AM CDT MON JUL 21 2008 .DISCUSSION... 08Z WATER VAPOR SHOWS A CLOSED UPPER LOW OFF THE NORTHERN CA COAST WITH A COUPLE SHORTWAVES MOVING FROM THE NORTHERN PLAINS INTO THE GREAT LAKES. RIDGING BETWEEN THESE FEATURES WAS FOUND OVER THE SOUTHERN ROCKIES AND PLAINS. A SHORTWAVE MOVING ACROSS THE NORTHER PLAINS HELPED TO SPARK CONVECTION ALONG THE 850 FRONT OVER NORTHERN NEB AND INTO IA. THE OUTFLOW FROM THIS CONVECTION HAS PUSHED INTO NORTH CENTRAL KS BUT IS LOOSING STEAM AS IT MOVES SOUTH. THE 06Z RUC SHOWS THE OUTFLOW BOUNDARY WASHING OUT THIS MORNING AND LOOSING ITS IDENTITY. MEANWHILE THE GFS KEEPS THE MAIN SYNOPTIC FRONT NORTH OF THE FORECAST AREA THROUGH 00Z AND THE 06Z NAM HAS TRENDED THIS WAY AS WELL. KEPT SOME SLIGHT CHANCE POPS ACROSS THE EXTREME NORTHERN SECTIONS OF THE AREA LATE THIS AFTERNOON IN CASE THERE IS A WEAK AREA OF CONVERGENCE. OTHERWISE ANTICIPATE TODAY TO BE SIMILAR TO YESTERDAY WITH LOTS OF SUNSHINE AND HIGHS IN THE UPPER 90S. 850 TEMPS DO NOT CHANGE TO MUCH FROM YESTERDAY SO HAVE GONE WITH PERSISTENCE WITH FORECAST HIGHS TODAY. ANOTHER ROUND OF CONVECTION SHOULD DEVELOP ALONG THE BOUNDARY TONIGHT...BUT WITH THE GFS AND NAM KEEPING THE 850 BOUNDARY ACROSS CENTRAL NEB AND SOUTHERN IA HAVE ADJUSTED POPS TO DOWN PLACE CHANCES ACROSS EAST CENTRAL KS. CONTINUED WITH POPS AROUND 50 PERCENT OVER THE FAR NORTHEAST. GIVEN THE AMOUNT OF INSTABILITY PROGGED BY THE MODELS WITH SFC DEWPOINTS IN THE LOWER 70S...THE THUNDERSTORMS COULD BECOME STRONG ENOUGH OVERNIGHT FOR DAMAGING WINDS AND SOME HAIL. FOR TUESDAY THROUGH WEDNESDAY NIGHT...MODELS SHOW THE FORECAST AREA REMAINING ON THE EASTERN EDGE OF THE UPPER RIDGE WITH THE BOUNDARY OVER THE AREA AND PWS INCREASING OVER 1.5 INCHES. FORECAST SOUNDINGS CONTINUE TO INDICATE THE MID LEVELS WILL NOT TO SO WARM THAT THEY WILL CAP THE BOUNDARY LAYER WITH 700MB TEMPS AROUND 10C. BECAUSE OF THIS HAVE CARRIED CHANCE POPS ACROSS THE EASTERN HALF OF THE FORECAST AREA THROUGH THE PERIOD FOR POSSIBLE SCATTERED CONVECTION. TEMPS SHOULD NOT BE QUIET AS WARM WITH AND EASTERLY WIND AND PARTLY CLOUDY SKIES. BUT THERE COULD BE A GOOD GRADIENT IN TEMPS DEPENDING ON WHERE THE BOUNDARY SETS UP. FAR WESTERN SECTIONS OF THE FORECAST AREA MAY REMAIN IN THE UPPER 90S WITH HIGHS AROUND 90 BEHIND THE BOUNDARY. DID NOT MAKE ANY CHANGES TO THE FORECAST FOR THURSDAY AND BEYOND. BUT LATER SHIFTS WILL NEED TO WATCH THE WEEKEND AS THE GFS CONTINUES TO SHOW ANOTHER BACKDOOR FRONT MOVING THROUGH SOMETIME DURING THE WEEKEND AS SHORTWAVE ENERGY DIVES SOUTHEAST ACROSS THE UPPER MIDWEST ALONG THE BACK SIDE OF THE MEAN EAST COAST TROUGH. THERE ARE SOME TIMING ISSUES BETWEEN THE GFS AND ECMWF WITH THIS FEATURE...BUT POPS MAY NEED TO BE INSERTED BEYOND THURSDAY TO ACCOUNT FOR THIS FEATURE WOLTERS && .AVIATION... VFR CONDITIONS CONTINUE FOR MOST OF THE TAF PERIOD. WILL NEED TO WATCH CONVECTIVE COMPLEXES IN NEBRASKA BUT FEEL THAT STRATUS OR OUTFLOW WINDS WILL REMAIN NORTH AND EAST OF TAF SITES. HAVE ADDED A 03Z GROUP TO ACCOUNT FOR INCOMING FRONTAL BOUNDARY LATE TOMORROW BUT WITH STRENGTH AND EXTENT STILL IN QUESTION DID NOT GO MORE THAN VCTS WITH CB. && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 935 PM CDT TUE JUL 22 2008 .UPDATE... SINCE 00Z...ISOLATED SHOWERS ALONG THE INTERSTATE 64 CORRIDOR HAVE ACTUALLY INCREASED SLIGHTLY. THE AIR MASS ACROSS THE REGION REMAINS VERY MOIST AND SLIGHTLY UNSTABLE. WATER VAPOR IMAGERY INDICATES A SHORTWAVE TROUGH APPROACHING THE LOWER OHIO VALLEY FROM THE NORTHWEST. RUC MODEL HINTS AT A SECONDARY SURFACE BOUNDARY MOVING SOUTH INTO THE LOWER OHIO VALLEY OVERNIGHT...WHICH WILL MARK THE LEADING EDGE OF DRIER AIR. BASED ON THESE SYNOPTIC FEATURES...EXPECT ISOLATED SHOWERS TO PERSIST THROUGH THE NIGHT. WOULD NOT BE SURPRISED TO SEE SOME LIGHTNING STRIKES. FORECAST WILL BE UPDATED TO REFLECT LATEST RADAR AND SATELLITE TRENDS. && .PREVIOUS DISCUSSION /ISSUED 308 PM CDT TUE JUL 22 2008/... FOR THE VERY SHORT TERM/TONIGHT/...CURRENT CONVECTIVE COMPLEX MOVING ACROSS SOUTHEAST MISSOURI SHOULD SCOUR OUT ANY REMAINING EFFECTIVE THETA-E AIR IMPINGING ON THE WFO PAH FORECAST AREA. THE CIRRUS SHIELD FROM THIS COMPLEX SHOULD ALSO RETARD ANY SIGNIFICANT RISE IN LOW LEVEL/SURFACE TEMPERATURES ENOUGH TO REACH CONVECTIVE VALUES THROUGH SOUTHERN IL...SOUTHWEST IN...NORTHWEST KY FOR THE REMAINDER OF THE AFTERNOON. TO HANDLE REMNANTS OF THE SERN MO MCS AND ISOLATED CONVECTION THROUGH THE EVENING...I HAVE LEFT A SMALL POP ACROSS THE SOUTHERN 2/3RDS OF THE WFO PAH FORECAST AREA THROUGH 10 PM...TAPERING RAIN CHANCES OFF RAPIDLY FROM 10 PM TUESDAY THROUGH 1 AM WEDNESDAY. BY THAT TIME...WIND FIELDS PER THE GFS/MOS GUIDANCE SUGGEST WEAK CONVERGENT FLOW WITH THE SWD MOVING SURFACE FRONT. BY 12Z THE SURFACE CONVERGENCE LINE SHOULD BE NEARING THE SOUTHERN BORDER COUNTIES OF MO/KY...WITH THE 925/850 MB FRONT CUTTING W-E ACROSS THE SOUTHERN 1/3 OF THE WFO PAH FORECAST AREA WEDNESDAY MORNING. WITH MOST OF THE LOWER LEVEL MOISTURE EFFECTIVELY SCOURED OUT...AND THE SHORTWAVE SHEARING AWAY FROM THE WFO PAH FORECAST AREA LATE TONIGHT...I DECIDED TO PULL ANY MENTION OF MEASURABLE POPS FROM THE FORECAST AFTER MIDNIGHT. WITH THE FRONTAL CONVERGENCE ZONE NEARBY AND WEAK WINDS...I DID...HOWEVER...ADD THE MENTION OF PATCHY FOG TO FAVORED LOCATIONS IN THE WFO PAH FORECAST AREA. FOR WEDNESDAY...INSOLATION AND WEAK LIFT ACROSS THE FRONTAL BOUNDARY WILL SUPPORT AT LEAST ISOLATED CONVECTION ALONG THE SOUTHERN EDGE OF THE WFO PAH FORECAST AREA BETWEEN THE SURFACE AND 925/850 MB FRONTAL BOUNDARY. WITH DRIER AND SOMEWHAT COOLER AIR INFILTRATING THE AREA...MAX TEMPERATURES SHOULD NOT RISE MUCH HIGHER THAN TODAYS RAIN-COOLED VALUES. FOR WEDNESDAY NIGHT INTO THURSDAY...A SHARPER NWLY FLOW ALOFT WILL IMPINGE ON THE AREA...WITH A GRADUAL SHARPENING/INCREASE OF THICKNESS/MOISTURE ALONG THE FRONTAL BOUNDARY OVER MO/AR...SETTING UP THE STAGE FOR WARM AIR ADVECTION PRECIPITATION TO MOVE BACK ACROSS SERN MO LATER THURSDAY MORNING/AFTERNOON. FOR THURSDAY NIGHT AND INTO EARLY NEXT WEAK...THE WFO PAH FORECAST AREA WILL BE POISED IN A QUASI-STATIONARY BAROCLINIC ZONE...WITH FASTER FLOW TO THE NORTHEAST ASSOCIATED WITH THE SEMI-PERMANENT CYCLONIC VORTEX ROTATING OVER EASTERN CANADA AND THE NORTHEAST QUARTER OF THE UNITED STATES...WITH A BROAD RIDGE CENTERED OVER WRN TX/OK...ERN CO/NM. IN BETWEEN...THE WFO PAH FORECAST AREA WILL BE ON THE RECEIVING END OF PERIODIC MESOSCALE CONVECTIVE SYSTEMS MOVING SEWD IN NW FLOW ALOFT. THE AMOUNT OF RETURN FLOW BETWEEN EACH SYSTEM WILL DETERMINE THE COVERAGE/INTENSITY/SEVERITY OF EACH SYSTEM DURING THIS TIME PERIOD. && .AVIATION... A COMPLEX OF THUNDERSTORMS THAT MOVED THROUGH MUCH OF THE QUAD STATE REGION THIS MORNING HAS EFFECTIVELY STABILIZED THE ATMOSPHERE FOR THIS AFTERNOON AND LIKELY TONIGHT AS WELL. ANOTHER COMPLEX OF THUNDERSTORMS WILL DIVE SOUTH SOUTHEAST THIS AFTERNOON ACROSS MUCH OF SOUTHEAST MISSOURI WITH THE POTENTIAL FOR BRIEF IFR CONDITIONS AND A PERIOD OF GUSTY NORTHWEST WINDS AT KPOF AND POINTS FURTHER EAST. THIS COMPLEX MAY BRING A PERIOD OF LIGHT RAIN TO KCGI...BUT THUNDER IS VERY UNLIKELY ALONG AND EAST OF THE MISSISSIPPI RIVER THIS AFTERNOON. HOWEVER...THESE AREAS MAY FEEL A WIND SHIFT TO THE WEST OR NORTHWEST...AS THE OUTFLOW BOUNDARY PUSHES EAST SOUTHEAST THROUGH THE REGION. TONIGHT A COLD FRONT WILL TRY TO PUSH THROUGH THE AREA...HOWEVER INSTABILITY WILL BE LACKING...SO THUNDER IS NOT ANTICIPATED WITH IT TONIGHT. COULD SEE SOME MVFR TO IFR FOG AHEAD OF THE FRONT AFTER 06Z TONIGHT...IF CLEAR AND CALM CONDITIONS DEVELOP AS FORECAST. MOST OF THE AREA SHOULD BE BEHIND THE FRONT BY 14Z WEDNESDAY...SO SCATTERED TO BROKEN LOW VFR TO MVFR CLOUDS WILL BE POSSIBLE ALONG WITH SOME LINGERING MVFR VISIBILITIES IN THE MORNING. HOWEVER...THESE CONDITIONS SHOULD BE SHORT-LIVED EAST OF THE MISSISSIPPI RIVER...AS NORTHEAST WINDS BRING IN DRIER CONDITIONS. IN SOUTHEAST MISSOURI...CLOUDS MAY LINGER THROUGH MIDDAY...AND WINDS MAY BE MORE VARIABLE...AS THE PROGRESS OF THE FRONT IS LESS CERTAIN IN THAT AREA. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ UPDATE...MY PREVIOUS SHORT TERM...DRS/SMITH PREVIOUS LONG TERM....SMITH AVIATION...DRS ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 154 PM EDT TUE JUL 22 2008 .SHORT TERM ...MESOSCALE UPDATE... REMNANTS...OUTFLOW BOUNDARY FROM CONVECTIVE COMPLEX OVER WESTERN KENTUCKY THIS MORNING IS PRODUCING SEVERE THUNDERSTORMS ACROSS PORTIONS OF SOUTH CENTRAL KY THIS AFTERNOON. MCVS APPARENT ON SAT LOOP AS WELL AS TWO CONVECTIVE OUTFLOW BOUNDARIES JUST WEST OF OUR CWA. AT PRESENT...ACTIVITY SEEMS ESPECIALLY CONCENTRATED IN THIS AREA. RUC ANALYSIS AND GOES SOUNDING DATA SUGGEST ACTIVITY WILL CONTINUE TO MOVE INTO EASTERN KENTUCKY AS CAPE INCREASES...TO AROUND 2000 J/KG ACROSS SOUTHERN PORTIONS OF OUR CWA THIS AFTERNOON. RTMA SFC ANALYSIS IS ALSO PICKING UP ON GOOD SFC CONVERGENCE IN THE VICINITY OF INTERSECTING OUTFLOW BOUNDARIES. ATTM EXPECT THE BULK OF ANY SEVERE WEATHER TO BE RESTRICTED TO AREAS SOUTH AND EAST OF EACH OUTFLOW BOUNDARY...OR GENERALLY ALONG AND EAST OF THE I75 CORRIDOR AND SOUTH OF THE MOUNTAIN PARKWAY. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /THE REST OF TODAY/ DECREASED SKY COVER SLIGHTLY ACROSS THE BOARD PER LATEST VISIBLE SATELLITE IMAGERY. INSPITE OF AN OVERCAST OF CIRROSTRATUS...THE OVERALL OPAQUE CLOUD COVER IS MUCH LESS THAN THE NUMBERS THAT WERE IN THE SKY COVER GRIDS PREVIOUSLY...SO APPROPRIATED ADJUSTMENTS WERE MADE. THE PRIMARY CHANGE HERE WAS DOWNGRADING A FEW OF THE ZONE BREAKUPS FROM MOSTLY CLOUDY TO PARTLY CLOUDY SKIES THROUGH MID AFTERNOON. ALSO DECREASED PRECIPITATION CHANCES QUITE A BIT THROUGH 18Z...AS THERE SIMPLY ISNT ANYTHING HAPPENING ACROSS EASTERN KENTUCKY RIGHT NOW CONVECTIVE LY SPEAKING. STILL ANTICIPATING SHOWERS AND STORMS TO FIRE LATER THIS AFTERNOON AND BECOME QUITE NUMEROUS ALONG A SLOWLY SOUTHWARD MOVING FRONTAL BOUNDARY...WITH A FEW STRONG TO SEVERE STORMS POSSIBLE ALONG THE WAY. THE CIRROSTRATUS LAYER IS KEEPING TEMPERATURES FROM INCREASING VERY MUCH AT ALL SO FAR TODAY. THE 14 AND 15Z SURFACE OBSERVATIONS INDICATE THAT HOURLY TEMPS ARE RUNNING SEVERAL DEGREES COOLER THAN THE PREVIOUS FORECAST INDICATED. MADE ADJUSTMENTS HERE PER THE TEMP TRENDS OBSERVED SO FAR THIS MORNING. ALSO RECALCULATED TODAYS MAX TEMPS BASED ON THE CHANGES MADE TO DIURNAL TREND...WITH TODAYS HIGHS 4 TO 6 DEGREES COOLER ACROSS THE BOARD. CORRESPONDING ADJUSTMENTS WERE ALSO NECESSARY WITH THE WEATHER AND QPF FORECASTS...BASED ON THE DECREASED POPS DURING THE LATE MORNING TO EARLY AFTERNOON PERIOD. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /THE REST OF TODAY/ CONVECTION HAS DISSIPATED AS EXPECTED AS IT MOVED INTO THE MORE STABLE AIRMASS OVER EASTERN KENTUCKY. WILL REMOVE THE WATCH HEADLINE FROM THE ZONE FORECAST PRODUCT BUT WILL LEAVE EVERYTHING ELSE AS IS FOR NOW AS IT CONTINUES TO APPEAR LIKE THUNDERSTORM ACTIVITY WILL INCREASE ONCE AGAIN LATER THIS AFTERNOON. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /TODAY THROUGH THURSDAY/ DEEP UPPER LEVEL TROUGH WILL BECOME ESTABLISHED OVER THE EASTERN GREAT LAKES BY THURSDAY. SURFACE COLD FRONT IS EXPECTED TO PROGRESS SOUTHEAST ACROSS THE AREA LATER TONIGHT WITH A COUPLE OF ROUNDS OF CONVECTION ANTICIPATED BEFORE IT PUSHES TO OUR SOUTH AND HIGH PRESSURE BUILDS INTO THE REGION LATE WEDNESDAY INTO THURSDAY. IT IS TOUCH TO GAGE WHAT WILL HAPPEN WITH THE INITIAL MCS ONGOING TO OUR NORTHWEST. THE AIRMASS OVER SOUTHEAST KENTUCKY IS ACTUALLY FAIRLY STABLE WITH LOWER SURFACE DEWPOINTS LEFT OVER AFTER THE CONVECTION EARLIER ON MONDAY. THE SYSTEM MAY ACTUALLY JUST DELIVER A GLANCING BLOW AS THE EASTERN END PROGRESSES ACROSS NORTHERN KENTUCKY/SOUTHERN OHIO AND THE WESTERN HALF DIVES SOUTH OR REDEVELOPS IN THE MORE UNSTABLE AIRMASS OVER THE WESTERN HALF OF THE STATE. THIS SCENARIO SEEMS TO BE SUPPORTED BY MCS MAINTENANCE PROBABILITIES BUT WE WILL JUST HAVE TO WATCH RADAR/SATELLITE TRENDS OVER THE NEXT HOUR OR TWO TO SEE HOW THIS SYSTEM HOLDS TOGETHER AS IT CONTINUES TOWARD THE AREA. WHATEVER HAPPENS WITH THE MCS EARLY THIS MORNING PRECIP WISE... THERE WILL LIKELY BE A LOT OF DEBRIS CLOUDINESS DURING THE MORNING HOURS BUT THIS SHOULD THIN AND SCATTER OUT ALLOWING FOR GOOD HEATING AND DESTABILIZATION DURING THE AFTERNOON HOURS... ESPECIALLY FOR SOUTHEAST KENTUCKY. ADDITIONAL MCS ACTIVITY SHOULD THEN DEVELOP ALONG THE FRONT AND PROGRESS SOUTHEAST INTO THE AREA LATE IN THE AFTERNOON INTO THE OVERNIGHT HOURS. THERE CONTINUES TO BE A SLIGHT RISK FOR SEVERE THUNDERSTORMS THROUGHOUT THE DAY TODAY AND OVERNIGHT TONIGHT WITH LARGE HAIL AND DAMAGING WINDS POSSIBLE. ANOTHER THING TO NOTE TODAY IS THE LARGE DIFFERENCES IN MOS GUIDANCE TEMPS WITH AN 8 DEGREE SPREAD BETWEEN THE MAV AND MET NUMBERS AT JKL AND LOZ. GFS SEEMS TO BE WARMING THE AREA TOO MUCH AT 850 MB POSSIBLY DUE TO CONVECTIVE FEEDBACK AND OVER DEVELOPMENT OF AN AREA OF LOW PRESSURE ON THE FRONT. NAM IS PROBABLY OVERDOING THE AMOUNT OF CLOUD COVER TODAY. OVERALL... EXPECT READINGS TO COME IN SIMILAR TO YESTERDAY OVER SOUTHEAST KENTUCKY BUT REMAIN SEVERAL DEGREES COOLER UP NORTH WHERE MORE CLOUDS ARE ANTICIPATED. WILL LINGER LOW CHANCE POPS ACROSS THE AREA ON WEDNESDAY AS THE FRONT SLOWLY WORKS INTO THE TENNESSEE VALLEY BUT SKIES SHOULD CLEAR WEDNESDAY NIGHT WITH SUNNY SKIES EXPECTED ON THURSDAY. A MUCH DRIER AIRMASS IS PROGGED TO FILTER IN BEHIND THE FRONT WITH SURFACE DEWPOINTS FALLING INTO THE 50S. THIS SHOULD ALLOW TEMPS TO FALL INTO THE UPPER 50S WEDNESDAY NIGHT IN OUR ORDINARILY COOLER VALLEY LOCATIONS AND KEEP CONDITIONS PLEASANT ON THURSDAY. .LONG TERM.../THURSDAY NIGHT THROUGH MONDAY/ GENERAL MODEL AGREEMENT CONTINUES WITH ADVERTISING NORTHWEST FLOW ALOFT ACROSS THE OHIO VALLEY AND NEW ENGLAND AS REINFORCING NORTHERN STREAM ENERGY ALLOWS FOR DEEPER CUTOFF LOWS TO DEVELOP ACROSS EASTERN CANADA. EASTERN KENTUCKY WILL BEGIN THE LONG TERM UNDER THE INFLUENCE OF HIGH PRESSURE. A SLOW MOVING COLD FRONT WILL THEN BRING DAILY CHANCES OF AFTERNOON AND EVENING ISOLATED TO SCATTERED CONVECTION TO THE AREA THROUGH THE REST OF THE WEEK AND INTO EARLY NEXT WEEK AS THE FRONT IS SLOW TO EXIT OFF TO THE SOUTHEAST. GIVEN THE NORTHWEST FLOW ALOFT...TEMPERATURES WILL RUN NEARLY SEASONAL FOR THIS TIME OF YEAR. THE HPC NUMBERS LOOKED REASONABLE ONCE AGAIN AND ONLY MADE A FEW TWEAKS TO THESE. && .AVIATION.../18Z TO 18Z/...UPDATED CLUSTER OF STRONG TO SEVERE THUNDERSTORMS IS HEADED FOR OUR SW COUNTIES AT TAF ISSUANCE TIME. HAVE TIMED THESE ACROSS KLOZ AND KSME AT MID AFTERNOON NEAR THE BEGINNING OF TAF VALID TIME. HAVE ONLY USED VCTS AT KJKL...WITH NORTHWARD DEVELOPMENT NOT TAKING PLACE SO FAR. AFTER THE CURRENT BATCH OF STORMS MOVES ACROSS OUR SOUTHERN COUNTIES THIS AFTERNOON...ADDITIONAL PRECIP THROUGH TONIGHT IS MUCH MORE QUESTIONABLE. ON WEDNESDAY...WILL LOOK FOR MORE DEVELOPMENT OF CONVECTION AS HEATING OCCURS AND A COLD FRONT MOVEST SOUTHEAST THROUGH THE AREA. ANY PRECIP SHOULD SWEEP SE OUT OF THE STATE WITH COLD FRONTAL PASSAGE IN THE AFTERNOON. OUTSIDE OF PRECIP...MAINLY VFR CONDITIONS ARE EXPECTED...WITH THE POSSIBLE EXCEPTION OF VALLEY FOG LATE TONIGHT INTO EARLY WEDNESDAY. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...ABE/AR/RAY LONG TERM....GEOGERIAN AVIATION...HAL ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 136 PM EDT TUE JUL 22 2008 .SHORT TERM...UPDATED ...MESOSCALE UPDATE... REMNANTS...OUTFLOW BOUNDARY FROM CONVECTIVE COMPLEX OVER WESTERN KENTUCKY THIS MORNING IS PRODUCING SEVERE THUNDERSTORMS ACROSS PORTIONS OF SOUTH CENTRAL KY THIS AFTERNOON. MCVS APPARENT ON SAT LOOP AS WELL AS TWO CONVECTIVE OUTFLOW BOUNDARIES JUST WEST OF OUR CWA. AT PRESENT...ACTIVITY SEEMS ESPECIALLY CONCENTRATED IN THIS AREA. RUC ANALYSIS AND GOES SOUNDING DATA SUGGEST ACTIVITY WILL CONTINUE TO MOVE INTO EASTERN KENTUCKY AS CAPE INCREASES...TO AROUND 2000 J/KG ACROSS SOUTHERN PORTIONS OF OUR CWA THIS AFTERNOON. RTMA SFC ANALYSIS IS ALSO PICKING UP ON GOOD SFC CONVERGENCE IN THE VICINITY OF INTERSECTING OUTFLOW BOUNDARIES. ATTM EXPECT THE BULK OF ANY SEVERE WEATHER TO BE RESTRICTED TO AREAS SOUTH AND EAST OF EACH OUTFLOW BOUNDARY...OR GENERALLY ALONG AND EAST OF THE I75 CORRIDOR AND SOUTH OF THE MOUNTAIN PARKWAY. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /THE REST OF TODAY/ DECREASED SKY COVER SLIGHTLY ACROSS THE BOARD PER LATEST VISIBLE SATELLITE IMAGERY. INSPITE OF AN OVERCAST OF CIRROSTRATUS...THE OVERALL OPAQUE CLOUD COVER IS MUCH LESS THAN THE NUMBERS THAT WERE IN THE SKY COVER GRIDS PREVIOUSLY...SO APPROPRIATED ADJUSTMENTS WERE MADE. THE PRIMARY CHANGE HERE WAS DOWNGRADING A FEW OF THE ZONE BREAKUPS FROM MOSTLY CLOUDY TO PARTLY CLOUDY SKIES THROUGH MID AFTERNOON. ALSO DECREASED PRECIPITATION CHANCES QUITE A BIT THROUGH 18Z...AS THERE SIMPLY ISNT ANYTHING HAPPENING ACROSS EASTERN KENTUCKY RIGHT NOW CONVECTIVE LY SPEAKING. STILL ANTICIPATING SHOWERS AND STORMS TO FIRE LATER THIS AFTERNOON AND BECOME QUITE NUMEROUS ALONG A SLOWLY SOUTHWARD MOVING FRONTAL BOUNDARY...WITH A FEW STRONG TO SEVERE STORMS POSSIBLE ALONG THE WAY. THE CIRROSTRATUS LAYER IS KEEPING TEMPERATURES FROM INCREASING VERY MUCH AT ALL SO FAR TODAY. THE 14 AND 15Z SURFACE OBSERVATIONS INDICATE THAT HOURLY TEMPS ARE RUNNING SEVERAL DEGREES COOLER THAN THE PREVIOUS FORECAST INDICATED. MADE ADJUSTMENTS HERE PER THE TEMP TRENDS OBSERVED SO FAR THIS MORNING. ALSO RECALCULATED TODAYS MAX TEMPS BASED ON THE CHANGES MADE TO DIURNAL TREND...WITH TODAYS HIGHS 4 TO 6 DEGREES COOLER ACROSS THE BOARD. CORRESPONDING ADJUSTMENTS WERE ALSO NECESSARY WITH THE WEATHER AND QPF FORECASTS...BASED ON THE DECREASED POPS DURING THE LATE MORNING TO EARLY AFTERNOON PERIOD. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /THE REST OF TODAY/ CONVECTION HAS DISSIPATED AS EXPECTED AS IT MOVED INTO THE MORE STABLE AIRMASS OVER EASTERN KENTUCKY. WILL REMOVE THE WATCH HEADLINE FROM THE ZONE FORECAST PRODUCT BUT WILL LEAVE EVERYTHING ELSE AS IS FOR NOW AS IT CONTINUES TO APPEAR LIKE THUNDERSTORM ACTIVITY WILL INCREASE ONCE AGAIN LATER THIS AFTERNOON. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /TODAY THROUGH THURSDAY/ DEEP UPPER LEVEL TROUGH WILL BECOME ESTABLISHED OVER THE EASTERN GREAT LAKES BY THURSDAY. SURFACE COLD FRONT IS EXPECTED TO PROGRESS SOUTHEAST ACROSS THE AREA LATER TONIGHT WITH A COUPLE OF ROUNDS OF CONVECTION ANTICIPATED BEFORE IT PUSHES TO OUR SOUTH AND HIGH PRESSURE BUILDS INTO THE REGION LATE WEDNESDAY INTO THURSDAY. IT IS TOUCH TO GAGE WHAT WILL HAPPEN WITH THE INITIAL MCS ONGOING TO OUR NORTHWEST. THE AIRMASS OVER SOUTHEAST KENTUCKY IS ACTUALLY FAIRLY STABLE WITH LOWER SURFACE DEWPOINTS LEFT OVER AFTER THE CONVECTION EARLIER ON MONDAY. THE SYSTEM MAY ACTUALLY JUST DELIVER A GLANCING BLOW AS THE EASTERN END PROGRESSES ACROSS NORTHERN KENTUCKY/SOUTHERN OHIO AND THE WESTERN HALF DIVES SOUTH OR REDEVELOPS IN THE MORE UNSTABLE AIRMASS OVER THE WESTERN HALF OF THE STATE. THIS SCENARIO SEEMS TO BE SUPPORTED BY MCS MAINTENANCE PROBABILITIES BUT WE WILL JUST HAVE TO WATCH RADAR/SATELLITE TRENDS OVER THE NEXT HOUR OR TWO TO SEE HOW THIS SYSTEM HOLDS TOGETHER AS IT CONTINUES TOWARD THE AREA. WHATEVER HAPPENS WITH THE MCS EARLY THIS MORNING PRECIP WISE... THERE WILL LIKELY BE A LOT OF DEBRIS CLOUDINESS DURING THE MORNING HOURS BUT THIS SHOULD THIN AND SCATTER OUT ALLOWING FOR GOOD HEATING AND DESTABILIZATION DURING THE AFTERNOON HOURS... ESPECIALLY FOR SOUTHEAST KENTUCKY. ADDITIONAL MCS ACTIVITY SHOULD THEN DEVELOP ALONG THE FRONT AND PROGRESS SOUTHEAST INTO THE AREA LATE IN THE AFTERNOON INTO THE OVERNIGHT HOURS. THERE CONTINUES TO BE A SLIGHT RISK FOR SEVERE THUNDERSTORMS THROUGHOUT THE DAY TODAY AND OVERNIGHT TONIGHT WITH LARGE HAIL AND DAMAGING WINDS POSSIBLE. ANOTHER THING TO NOTE TODAY IS THE LARGE DIFFERENCES IN MOS GUIDANCE TEMPS WITH AN 8 DEGREE SPREAD BETWEEN THE MAV AND MET NUMBERS AT JKL AND LOZ. GFS SEEMS TO BE WARMING THE AREA TOO MUCH AT 850 MB POSSIBLY DUE TO CONVECTIVE FEEDBACK AND OVER DEVELOPMENT OF AN AREA OF LOW PRESSURE ON THE FRONT. NAM IS PROBABLY OVERDOING THE AMOUNT OF CLOUD COVER TODAY. OVERALL... EXPECT READINGS TO COME IN SIMILAR TO YESTERDAY OVER SOUTHEAST KENTUCKY BUT REMAIN SEVERAL DEGREES COOLER UP NORTH WHERE MORE CLOUDS ARE ANTICIPATED. WILL LINGER LOW CHANCE POPS ACROSS THE AREA ON WEDNESDAY AS THE FRONT SLOWLY WORKS INTO THE TENNESSEE VALLEY BUT SKIES SHOULD CLEAR WEDNESDAY NIGHT WITH SUNNY SKIES EXPECTED ON THURSDAY. A MUCH DRIER AIRMASS IS PROGGED TO FILTER IN BEHIND THE FRONT WITH SURFACE DEWPOINTS FALLING INTO THE 50S. THIS SHOULD ALLOW TEMPS TO FALL INTO THE UPPER 50S WEDNESDAY NIGHT IN OUR ORDINARILY COOLER VALLEY LOCATIONS AND KEEP CONDITIONS PLEASANT ON THURSDAY. .LONG TERM.../THURSDAY NIGHT THROUGH MONDAY/ GENERAL MODEL AGREEMENT CONTINUES WITH ADVERTISING NORTHWEST FLOW ALOFT ACROSS THE OHIO VALLEY AND NEW ENGLAND AS REINFORCING NORTHERN STREAM ENERGY ALLOWS FOR DEEPER CUTOFF LOWS TO DEVELOP ACROSS EASTERN CANADA. EASTERN KENTUCKY WILL BEGIN THE LONG TERM UNDER THE INFLUENCE OF HIGH PRESSURE. A SLOW MOVING COLD FRONT WILL THEN BRING DAILY CHANCES OF AFTERNOON AND EVENING ISOLATED TO SCATTERED CONVECTION TO THE AREA THROUGH THE REST OF THE WEEK AND INTO EARLY NEXT WEEK AS THE FRONT IS SLOW TO EXIT OFF TO THE SOUTHEAST. GIVEN THE NORTHWEST FLOW ALOFT...TEMPERATURES WILL RUN NEARLY SEASONAL FOR THIS TIME OF YEAR. THE HPC NUMBERS LOOKED REASONABLE ONCE AGAIN AND ONLY MADE A FEW TWEAKS TO THESE. && .AVIATION.../12Z TO 12Z/ WITH THE DISSIPATION OF THE EARLIER MCS TO OUR NORTH ATTENTION NOW TURNS TO THE TIMING FOR THE RENEWAL OF ACTIVITY. THIS WILL BE HARD TO PIN DOWN SO...BASED ON RECOVERY TIME AND DIURNAL HEATING...HAVE INCLUDED A PREVAILING VCTS FROM 18Z ON...INTENDING TO PROVIDE MORE SPECIFICS VIA FUTURE UPDATES OR AMENDMENTS. DID TRY TO TIME A NEW ROUND OF THUNDERSTORM ACTIVITY FOR LATER THIS EVENING FROM 01Z INTO THE EARLY MORNING HOURS. WINDS STILL LOOK TO BE MAINLY LIGHT FROM THE SOUTHWEST...OUTSIDE OF ANY STORMS. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...ABE/AR/RAY LONG TERM....GEOGERIAN AVIATION...GREIF ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 1005 PM CDT MON JUL 21 2008 .UPDATE... FORECAST UPDATED FOR SEVERE THUNDERSTORM WATCH VALID UNTIL 3 AM FOR SOUTHWEST INDIANA AND PARTS OF SOUTHERN ILLINOIS. RAISED POPS FOR MOST AREAS OVERNIGHT. STRONG INSTABILITY AND VERY MOIST LOW LEVELS WILL ALLOW STORMS TO MAINTAIN THEIR ORGANIZATION AS THEY CROSS THE FORECAST AREA OVERNIGHT. ALTHOUGH SOME WEAKENING OF THE OVERALL MCS IS LIKELY...INCREASING LOW LEVEL INFLOW /PER 00Z RUC MODEL/ WILL SUSTAIN NEW DEVELOPMENT ALONG THE UPSHEAR SIDE OF THE MCS ALL NIGHT. && .PREVIOUS DISCUSSION /ISSUED 257 PM CDT MON JUL 21 2008/... THIS FORECAST PACKAGE POINTS TO THE DIFFICULTY OF TRYING TO RESOLVE THE SPATIAL AND TEMPORAL DIFFERENCES WITH MISO/MESOSCALE WEATHER FEATURES WITHIN LONGER RANGE FORECASTS INCORPORATING MESOSCALE AND SYNOPTIC SCALE NUMERICAL GUIDANCE...EXCLUDING MOS BASED GUIDANCE. CURRENT THUNDERSTORM COMPLEX TO THE EAST OF THE WFO PAH FORECAST AREA IS FEEDING OFF A RICH THETA-E RIDGE EVIDENT AT THE 925-850 MB MANDATORY LEVEL CHARTS THIS MORNING...ALONG THE EASTERN LIMB OF THE SURFACE TO 500 MB RIDGE CENTERED ALONG THE LOWER MISSISSIPPI RIVER VALLEY TODAY. THE KEY TO THIS FORECAST PACKAGE WILL BE THE INTERACTION BETWEEN THE WESTERN/SOUTHWESTERN U.S. RIDGE AND THE GREAT LAKES CYCLONIC VORTEX...WITH MINOR PERTURBATIONS ASSOCIATED WITH MINOR SHORTWAVES AND T.S DOLLY IN THE GULF OF MEXICO. THE MAIN TWO NUMERICAL GUIDANCE PACKAGES USED IN THIS FORECAST PACKAGE...THE HIGH RESOLUTION ECMWF AND THE 40KM GFS...DIFFER SLIGHTLY ON THE INFLECTION POINT BETWEEN THE RIDGE AND THE CLOSED LOW CIRCULATION. THE GFS IS INITIALLY MORE AGGRESSIVE IN ROTATING DISTURBANCES FURTHER SOUTH WITH THE CLOSED LOW...PUSHING AN ATTENDANT COLD FRONT SOUTH OF THE REGION BY WEDNESDAY MORNING. THIS WOULD ALLOW HIGH PRESSURE TO BRIEFLY TAKE HOLD ON THURSDAY...BEFORE SHIFTING SOMEWHAT EAST OF THE AREA ON FRIDAY...TEMPORARILY WORKING THE COLD FRONT BACK INTO THE AREA LATE THURSDAY INTO EARLY SATURDAY. THE ECMWF IS SLIGHTLY SLOWER THAN THE GFS WITH THE FRONTAL BOUNDARY AND MORE AGGRESSIVE WITH THE RETURN MOISTURE BACK ACROSS THE WFO PAH FORECAST AREA LATE THURSDAY INTO AS LATE AS NEXT MONDAY. FOR NOW...I HAVE UTILIZED A BLEND OF THE GFS AND ECMWF THROUGH THURSDAY...WITH AN EMPHASIS ON THE ECMWF SOLUTION BEYOND THE THURSDAY TIME FRAME. FOR THE WFO PAH FORECAST AREA...THIS WILL MEAN A MODERATE CHANCE FOR SHOWERS AND THUNDERSTORMS WITH THE INITIAL PUSH OF THE COLD FRONT INTO THE AREA TONIGHT AND TUESDAY...WITH A SMALL BREAK IN THE RAIN WEDNESDAY NIGHT. SHOWERS AND THUNDERSTORMS SHOULD RETURN FROM THE WEST ON THURSDAY...WITH SMALL...MAINLY DIURNAL CHANCES FOR RAIN EXPECTED THROUGH SUNDAY. GREATEST FORECAST UNCERTAINTY FOR MAX/MIN TEMPERATURE FORECAST REMAINS FOCUSED DURING THE WEDNESDAY THROUGH FRIDAY TIME FRAME...AS MOISTURE AND WIND FIELDS COMPLICATE DIURNAL TEMPERATURE TRENDS. && .AVIATION... VFR CONDITIONS EXPECTED OUTSIDE OF THUNDERSTORMS THROUGH TUESDAY. ONE AREA OF THUNDERSTORMS WILL SLIP EAST OF THE AREA THIS AFTERNOON...WITH JUST A FEW SHOWERS LEFT OVER IN THE EVANSVILLE TRI STATE AREA THROUGH MID AFTERNOON. NEXT CHANCE OF CONVECTION WILL BE LATE TONIGHT...MAINLY IN THE NORTH WHERE SOME STRONG STORMS MAY PRODUCE MVFR CONDITIONS AND GUSTY WEST TO NORTHWEST WINDS. INHERITED PROB30 GROUPS AT KEVV AND KOWB...SO LEFT IT WITH LITTLE MODIFICATION. MAIN QUESTION FOR THUNDER CHANCES TUESDAY WILL BE WHERE THE COLD FRONT OR EFFECTIVE OUTFLOW BOUNDARY SETS UP. CURRENT FEELING IS THAT THE BOUNDARY WILL BE SMACK IN THE MIDDLE OF THE AREA...WHICH WILL LEAD TO THUNDERSTORMS OVER MUCH OF THE AREA IN THE AFTERNOON AND EVENING...WITH A TREND TOWARD THE SOUTH WITH TIME. FOR THE 18Z TAFS...KEPT THEM DRY 12Z-18Z FOR NOW. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ UPDATE...MY PREVIOUS...DRS/SMITH AVIATION...DRS ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 130 AM EDT MON JUL 21 2008 .UPDATE LATE EVENING... SEVERE THUNDERSTORMS WATCH HAS EXPIRED. HOWEVER THERE AREA STILL STRONG THUNDERSTORMS ONGOING FROM NORTHERN DUBOIS COUNTY SOUTHEAST THROUGH SOUTHERN ORANGE...CRAWFORD...PERRY AND HARRISON COUNTIES IN INDIANA INTO HARDIN COUNTY KENTUCKY. THESE STORMS WILL BE CAPABLE OF VERY HEAVY RAIN FOR THE NEXT COUPLE OF HOURS. THE STORMS WILL DECREASE SLOWLY BUT A COUPLE OF THE STORMS COULD STILL BECOME SEVERE FOR THE NEXT HOUR OR SO. && .MESO UPDATE (MID EVENING)... EXTENDED SEVERE THUNDERSTORMS WATCH NUMBER 710 TO 11 PM EDT. THIS IS DUE TO REFORMATION OF STRONG STORMS ACROSS CENTRAL INDIANA. .MESO UPDATE (EARLY THIS EVENING)... WELL...1ST BATCH OF CONVECTION FROM MID AFTERNOON OVER BLUEGRASS REGION HAS PUSHED INTO JKL CWA...AND ONLY BROUGHT BRIEF GUSTY WINDS...FEW CG LIGHTNING STRIKES AND BRIEF HEAVY RAINFALL. NEXT SVR STORM IS STRADDLING THE OWEN AND HENRY KY CO LINE...AND TRAJECTORY WILL TAKE THIS FLEMING COUNTY. MAIN CONCERN IS THE SWRN EDGE OF AN MCS OVER CENTRAL PART OF IND AREA. THESE STORMS HAVE A VERY TIGHT REFLECTIVITY GRADIENT OVER OWEN AND MONROE COUNTY LINE IN INDIANA AND DEFINITELY HAS A SEVERE WIND THREAT. WITH 70 DEW POINTS...LIS IN THE -5 TO -7 C RANGE...AND CAPES IN THE 2500-3300 J/KG...THERE IS PLENTY OF MOISTURE AND INSTABILITY TO WORK WITH IN THIS NOTORIOUS NW FLOW. THE 12Z U/A SOUNDINGS AT ILN...ILX...AND BNA ALL DENOTE DAMAGING WIND THREAT WITH LOADS OF DRY AIR ENTRAINMENT FROM 700-500 MB. THE CORFIDI VECTORS ON THE LAST RUC TAKE THIS COMPLEX INTO THE SCOTT AND JEFFERSON COUNTY LINE AROUND 2330Z. IF THE RADAR TRENDS CONTINUE THESE COUNTIES CAN EXPECT A SVR. && .SHORT TERM (TONIGHT AND MONDAY)... SCT TSTMS HAVE DEVELOPED OVER A PART OF CNTRL KY THIS AFTERNOON ALONG AND AHEAD OF A SUBTLE CLOUD BOUNDARY WITH A CU/TCU FIELD AHEAD OF BOUNDARY AND LESS CLOUD COVER JUST BEHIND IT. EXPECT THESE STORMS TO CONTINUE DEVELOPING SEWD INTO PARTS OF E-CNTRL AND S-CNTRL KY THRU LATE AFTERNOON BEFORE DISSIPATING THIS EVENING. THE STRONGEST CELLS SHOULD PRODUCE BRIEF HEAVY RAIN...WIND GUSTS OF 30-40 MPH... AND POSSIBLY SMALL HAIL. THE NEXT CONCERN IS AN AREA OF DEVELOPING CONVECTION OVER CNTRL IL AND CNTRL IN. THIS AREA IS IN A REGION OF WEAK LOW-LEVEL CONFLUENCE AND MODERATE TO STRONG INSTABILITY. TSTMS SHOULD CONTINUE TO INCREASE IN COVERAGE AND MOVE EAST-SOUTHEAST LATE THIS AFTERNOON AND EARLY EVENING. STORM TRAJECTORY AND STEERING FLOW ALOFT SUGGEST MAIN AXIS OF STORMS SHOULD MOVE EVENTUALLY INTO SERN IN TO BETWEEN LOUISVILLE AND CINCINNATI...PROBABLY CLIPPING ERN PART OF OUR S-CNTRL IN COUNTIES. SPC HAS JUST ISSUED SVR TSTM WATCH 710 TIL 01Z FOR ERN IL AND CNTRL AND PARTS OF SRN IN. THESE STORMS SHOULD ALSO WEAKEN LATER THIS EVENING AS DIURNAL INSTABILITY WANES. OVERNIGHT...ADDITIONAL TSTMS MAY FORM WELL TO OUR NW AND POSSIBLY DEVELOP INTO ANOTHER MCS. THIS SHOULD NOT AFFECT OUR NRN COUNTIES OVERNIGHT. INSTEAD...SHOULD BE DRY WEATHER OVERNIGHT WITH AREAS OF HAZE/FOG. ON MONDAY...OUTFLOW BOUNDARIES FROM ANY MCS ACTIVITY TO OUR N AND W MAY SERVE AS EFFECTIVE BOUNDARIES FOR RENEWED TSTM DEVELOPMENT MON AFTERNOON WITHIN A HOT AND UNSTABLE AIR MASS. APPEARS NRN HALF OF FCST AREA WILL BE MOST SUSCEPTIBLE TO SCT DIURNAL CONVECTION WITH ISOLATED WET MICROBURTS POSSIBLE. .LONG TERM (MONDAY NIGHT THRU SUNDAY)... MON NGT THRU WED NGT... LATE MON NIGHT INTO TUE SHUD BE PRIME TIME FOR CONVECTIVE DEVELOPMENT ACROSS OUR FORECAST AREA (FA) WITH MCS POTENTIAL MON NGT...MAINLY FOR OUR NRN FA AND POTENTIAL REDEVELOPMENT TUE. LONGWAVE TROF...EMBEDDED WITH SEWD MOVG SHRTWV TROFS...FORECAST TO SHARPEN/DIG INTO OUR FA BY WED WITH TROF AXIS EAST OF OUR AREA BY WED NIGHT. ASSOCIATED CDFNT WILL LIKELY BE MEANDERING ACRS SRN INDIANA AT THE START OF THIS PERIOD. SHORT RANGE MODELS/ENSEMBLES INDICATE A POTENTIAL MCS DEVELOPING NEAR/NORTH OF BNDRY AS IT SLIPS SWD INTO N-CNTRL KY BY 12Z TUE. CURRENT HI CHC POPS FOR OUR NRN FA AND LOWER CHC SOUTH SEEM REASONABLE AND WILL LEAVE FOR MON NIGHT. SUFFICIENT MOISTURE/INSTABILITY/SHEAR SHUD BE IN PLACE FOR STRONG STORMS...WITH PERHAPS A FEW REACHING SVR LEVELS. BNDRY CONTINUES SLOWLY SEWD TUE/TUE NIGHT WITH ADDITIONAL SHOWERS/STORMS EXPECTED TO DEVELOP NEAR FRONT AS AFOREMENTIONED TROF CONTINUES TO DIG INTO THE LOWER OHIO VALLEY. SHORT RANGE ENSEMBLES SHOW SHOWERS/STORMS TO BE MOST WIDESPREAD TUE WITH DECAYING...THEN REDEVELOPING MCS DROPPING SWD ACRS OUR FA. WILL RAISE POPS AT THAT TIME TO 50% ENTIRE FA. GREATEST SVR THREAT/DEEP CONVECTION...WOULD APPEAR TO BE ACRS OUR SRN FA TUE AFTN/EARLY TUE NIGHT WITH FRONT OVER THAT AREA DURING THE DIURNAL INSTABILITY MAX...ASSUMING CONVECTIVE DEBRIS DOES NOT SLOW SIGNIFICANTLY DAYTIME HEATING. BY WED...RAIN CHCS SHOULD BE DECREASING WITH DEEP MOISTURE AND CONVERGENCE PROGGED ALONG BNDRY ACRS TENNESSEE. ONGOING FCST INDICATES AS MUCH. THU THRU SUN... TYPICAL LATE JULY TEMPS THRU THIS PERIOD WITH MOSTLY DRY CONDITIONS. BEST CHC POPS (30-40%) WILL BE RESERVED FOR FRI. MEDIUM RANGE MODELS ARE SIMILAR WITH SHOWING WEAK NW UPR FLO THRU MUCH OF THE PERIOD...HOPEFULLY FLO WILL BE STRONG ENOUGH TO PUSH A COUPLE OF COOL FRONTS SWD THRU OUR FA...WHICH BECOMES HARDER TO DO AS WE GET LATER INTO THE SUMMER. FIRST SUCH FRONT (QSTNRY) FORECAST TO BE ACRS TN THU WITH HIGH PRES EXTENDING FROM THE LOWER GREAT LAKES INTO THE LOWER OH VLY. HAVE CHOSEN TO REMOVE SLIGHT CHC POPS FOR THAT PERIOD FROM THE PREV FCST. FOR THU NGT/FRI/FRI NIGHT...SFC WAVE DEVELOPS ON BNDRY AND MOVES ACRS MO/LWR OH VLY WITH GFS ENSEMBLES/OPS ECMWF AND HPC INDICATING AT LEAST SCATTERED SHOWERS/TSTMS...ESPECIALLY FRI AHEAD OF WAVE IN STRONGEST SLY/MOIST FLO. WENT WITH HPC FOR THE WEEKEND (LOW CHC POPS) WITH A SECOND DECELERATING FRONT EXPECTED TO BE MEANDERING ACRS OUR FA WITH HIGHEST POPS SOUTH...NEAREST FRONT. && .AVIATION (06Z TAFS)...UPDATED THUNDERSTORMS HAVE ENDED FOR THE NIGHT AT SDF AND LEX. MID LEVEL CLOUDS WILL CONTINUE THROUGH 10Z AT SDF AND LEX...BUT SKIES SHOULD CLEAR DURING THE PRE-DAWN HOURS. EXPECT LIGHT WINDS AND SOME MARGINALLY MVFR VISIBILITIES DOWN TO 5SM IN HAZE THIS MORNING THROUGH 14Z. PARTLY CLOUDY SKIES WILL DEVELOP THIS AFTERNOON AND SCATTERED THUNDERSTORMS ARE AGAIN POSSIBLE AFTER 17Z. LIKE YESTERDAY...SOME STORMS MAY BE STRONG WITH GUSTY WINDS AND LOCALLY INTENSE RAIN. SKIES SHOULD STAY VFR TOMORROW EXCEPT WITHIN THUNDERSTORMS. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ UPDATE.......JSD SHORT TERM...TWF LONG TERM....JDK AVIATION.....JSD ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 204 PM EDT TUE JUL 22 2008 .SYNOPSIS... AN APPROACHING COLD FRONT WILL RESULT IN SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS INTO WEDNESDAY. HIGH PRESSURE WILL BUILD INTO THE REGION FOR LATE IN THE WEEK...BRINGING DRY AND SEASONABLY COOL CONDITIONS. THE NEXT FRONTAL SYSTEM WILL IMPACT THE AREA OVER THE WEEKEND. && .NEAR TERM /THROUGH WEDNESDAY/... SCATTERED SHOWERS/ISOLATED TSTMS ARE DEVELOPING ACROSS NORTHEAST OH/NORTHWEST PA ALONG A LAKE INDUCED BOUNDARY...OTHERWISE THE NEXT WAVE IS APPROACHING FROM THE WESTERN GREAT LAKES. THIS WAVE WILL ROTATE ACROSS THE AREA EARLY THIS EVENING ACROSS EASTERN OHIO...AND ACROSS WESTERN PA EASTWARD LATE THIS EVENING/OVERNIGHT. AS HAS BEEN THE CASE THE LATE COUPLE OF DAYS...THE POTENTIAL FOR STORMS TO PRODUCE LOCALLY STRONG WINDS WILL CONTINUE. NAM/GFS/SREF ALL DEPICT A SLOWER EXIT OF THE FORCING...ESPECIALLY ALONG THE SE RIDGES...THUS WILL KEEP HIGH END CHC POPS THROUGH MOST OF WEDNESDAY THERE...WITH DIMINISHING PRECIP COVERAGE FURTHER NORTH AND WEST. NOTICEABLY COOLER AND DRIER CONDITIONS WILL WORK IN ACROSS NORTHERN SECTIONS WEDNESDAY WITH HIGHS IN THE MID 70S WITH DEWPOINTS FALLING INTO THE 50S. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... RESIDUAL ISOLATED SHWRS WILL END WEDNESDAY EVENING ACROSS THE RIDGES AS THE UPPER LOW EXITS TO THE EAST. HIGH PRESSURE WILL BUILD IN FOR THE REMAINDER OF THE WORK WEEK...BRINGING DRY AND COOLER CONDITIONS...WITH MOST LOCATIONS IN THE 50S WEDNESDAY NIGHT AND THURSDAY NIGHT. && .LONG TERM /SATURDAY THROUGH TUESDAY/... MEDIUM RANGE MODELS CONTINUE TO BE IN DECENT AGREEMENT BRINGING THE NEXT FRONTAL BOUNDARY ACROSS THE REGION SATURDAY...WITH PERHAPS A SECONDARY FEATURE FOR SUNDAY. WILL KEEP CHANCE POPS FOR SAT/SUN. SOME DIFFERENCES FOR EARLY NEXT WEEK...WITH THE GFS SHOWING YET ANOTHER WAVE CROSSING THE AREA...AND THE ECMWF SHOWING THE FEATURE DEPARTING TO THE SOUTH. WILL KEEP MINIMAL RESIDUAL CHANCES FOR MONDAY...WITH DRY CONDITIONS FOR TUESDAY. NEAR NORMAL TEMPERATURES WILL PREVAIL FOR THE LONG TERM. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... BLEND OF MOST RECENT RUC NAM AND SREF MODEL RUNS SUGGEST A BAND OF SCATTERED TO NUMEROUS THUNDERSTORMS CAN MOVE THROUGH THE UPPER OHIO VALLEY BETWEEN 19Z AND 02Z. A SECOND BAND OF SHOWERS AND SCATTERED THUNDERSTORMS CAN MOVE THROUGH THIS AREA LATE TONIGHT. RECENT RADAR DATA SHOWING ISOLATED THUNDERSTORMS SPROUTING WITHIN THE LAKE ERIE BREEZE ZONE TO THE VICINITY OF THE I-80 CORRIDOR SUPPORTS THE CONTENTION OF THE INITIAL THUNDERSTORM BAND. SREF DEEP LAYER BULK SHEAR AND CAPE VALUES SUPPORT SPC THINKING THE STORMS MAY DEVELOP SEVERE CHARACTERISTICS. SO THUNDERSTORM GUSTS NEAR 30 KTS INCLUDED WITH 3-HOUR WINDOW OF THUNDERSTORM ONSET ALONG WITH MVFR. THIS WILL BE MONITORED FOR UPWARD ADJUSTMENT AS NEEDED. THE DEGREE OF DESTABILIZATION WITH THE FRONTAL BAND OF SHOWERS AND THUNDERSTORMS WILL DEPEND ON SEVERAL FACTORS THAT INCLUDE HOW MUCH CAPE IS USED TO SUPPORT PROPOSED INITIAL BAND AND EXACT TIMING OF SLOW COLD FRONTAL PASSAGE. SO AT THIS TIME HAVE FORECASTED A PERIOD OF SHOWERS LATE TONIGHT ALBEIT THERE CAN ALSO BE SUFFICIENT RESIDUAL LIFT AND INSTABILITY TO GENERATE SCATTERED THUNDERSTORMS AND MVFR. WITH THE EXPECTED RAIN MOISTENING OF THE SURFACE LAYER...HAVE FORECASTED LATE NIGHT FOG WITH WIDESPREAD MVFR AND SCATTERED IFR. BY WEDNESDAY NIGHT...EXPECT THE SURFACE LAYER TO SUFFICIENTLY DRY TO END SHOWER CHANCES TO INDUCE WIDESPREAD VFR. BASED ON BLEND OF SREF AND GEFS MODEL RUNS EXPECT VFR TO BE PREVALENT THURSDAY AND FRIDAY WITH ONLY IFR POSSIBILITY IN ISOLATED EARLY MORNING FOG PATCHES. LATEST GEFS MODEL RUN SHOWS ANOTHER FRONT AFFECTING THE UPPER OHIO VALLEY SATURDAY AND SUNDAY RAISING THE CHANCES OF SHOWERS AND THUNDERSTORMS AND AT LEAST MVFR CONDITIONS. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$ md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 429 AM EDT TUE JUL 22 2008 .SYNOPSIS... A COLD FRONT OVER OHIO WILL BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS TODAY AND WEDNESDAY. THIS FRONT WILL STALL OUT TO OUR SOUTH THURSDAY...AND INCH NORTHWARD TOWARD THE END OF THE WEEK. && .NEAR TERM /TODAY/... LOOKS LIKE A FAIRLY ACTIVE PATTERN OVER THE NEXT COUPLE OF DAYS. MCS OVER OH HAS MAINTAINED ITSELF RLVTLY WELL THRU THE OVRNGT HRS. HRRR RUC SHOWS A SOMEWHAT INTERESTING PSBLTY W/ THIS...THAT THE MCS WL DETERIORATE AS IT MOVES ACROSS W.V. BUT THAT A LN A RW/TRW WL MAKE IT E OF THE MTNS EARLY THIS AFTN. NEXT SHIFT WL KEEP AN EYE ON THIS. SPC HAS ENTIRE MID ATLC IN A SLT RISK FOR THIS AFTN. THE MCS HAS HAD A NGT OF PRODUCING WATCHES...AND IF IT IS ABLE TO REGENERATE THIS AFTN THIS COULD AGN BE THE CASE FOR OUR RGN. ANOTHER VERY WARM DAY...ALTHO THIS HAS CERTAINLY NOT BEEN AS OPPRESSIVE AS MANY OF THE LATE JULS I HV SPENT HERE. TEMPS 90-95 THIS AFTN...HEAT INDEX VALUES 95-100. CLD WISE DAY SHOULD START OUT BTWN THE SHORT WV THAT PRODUCED THE RW AFTR MDNGT AND THE MCS...SO MAINLY SUNNY THIS MRNG THEN INCRSG CLDS W/ CHC-LKLY POPS THIS AFTN. && .SHORT TERM /TONIGHT/... UPPER TROF OVER ERN ONTARIO BEGINS TO DIG OVER THE NERN U.S. TNGT FORMING A SOMEHAT ATYPICAL LATE JUL PATTERN. BEING ON THE ERN SIDE OF THE TROF CHCS OF PCPN WL EXIST AGN TNGT. POPS MAINLY 40-50...BUT THESE MAY NEED TO BE INCRSD BASED ON HOW THINGS DVDLP TDA. TEMPS RANGE FM THE M60S HIGHLANDS TO MU70S IN CITIES AND ALONG CHES BAY. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... WED LOOKS TO BE ACTIVE...ONE OF THOSE SITUATIONS WHERE TOO MUCH OF A LOW LEVEL MOISTURE SURGE DRNG THE MRNG HRS MAY LIMIT OR STABILIZE THE ENVRMNT FOR AFTN CONVECTION. FORCING HOWEVER DOESN/T LOOK TO BE AN ISSUE. A STRONG POSITIVELY TILTED AND APRCHNG UPPER TROF AXIS WILL DIG VERY FAR SOUTH /FOR A LATE-JULY SYSTEM/ INTO THE TN VLY AND SRN APLCHNS INTO WED AFTN. ALL ALONG THE ERN SEABOARD /IN THE WARM SECTOR OF THE APRCHNG SHRTWV/...A FAIRLY INTENSE MID SUMMER LL JET MAX LOOKS TO DEVELOP. THIS FEATURE...ALONG W/ HIGH DWPNTS AND MID LEVEL SUBSIDENCE BEHIND THE SYSTEM...COULD LIKELY DEVELOP SOME AREAS OF INTENSE CONVECTION UP/DOWN THE ERN SEABOARD. OVRNGHT WED INTO THURS MRNG THE TROF AXIS WILL SHARPLY TURN NE/WRD AND PUSH THE REMAINING ACTIVITY OFF THE ATLNC COAST. THE BIG CHANGE IN LR MODELS FROM 24 HRS AGO IS THE WEEKEND SET-UP FOR THE UPPER LOW OVER THE GREAT LAKES. A DECENT AGREEMENT IS HELD AMONGST GUIDANCE ABOUT THE SHARP TROF AXIS THAT GRADUALLY WORKS IT/S WAY ACROSS THE ERN HALF OF THE COUNTRY...INITIALLY POSITIVELY TILTED OVER THE WRN GREAT LAKES AND MID MS VALLEY...THEN BECOMES PHASES N/S OVER THE APLCHN CHAIN ON THURS /DRIVING THE ACTIVITY OFF THE COAST/. THEN THE UPPER TROF AXIS GRADUALLY TILTS NEGATIVELY AS IT MOVES UP THE NORTHEAST COAST. PREV RUNS FROM THIS POINT PUSHED THE UPPER LOW OUT /FROM ERN QUEBEC OUT INTO THE NRN ATLNC/ BY A DEVELOPING UPPER ON THE LEE OF THE CANADIAN ROCKIES...INTO THE PLAINS OF S CNTL CANADA. LATEST GFS/ECMWF RUNS NOW COMBINING THE TWO SYSTEMS JUST NORTH OF THE GREAT LAKES REGION OVER THE WEEKEND...MAKING FOR ONE LAST PASS OF ACTIVE WEATHER BEFORE EXITING NORTH AMERICA. AT THIS POINT...THE MAIN EFFECT ON THE MID ATLNC LOOKS TO BE DAILY INSTABILITY INCREASES AND SCT/D CONVECTION EACH AFTN...PSBLY INTO THE WEEKEND IF THE SFC FRONT STALLS OR SLOWS IT/S PROGRESS ACROSS THE REGION. && .AVIATION /TODAY THROUGH SATURDAY/... VFR CONDS THIS MRNG. TSTM ACTVTY IS PSBL THIS AFTN WICH COULD GNR8 STRONG WINDS. FOR TIME BEING ONLY HV VCTS REMARK IN TAFS. THIS WL NEED TO BE REFINED LATER THIS MRNG/THIS AFTN. TSTM WL BE PSBL DURG OVRNGT HRS AS WELL. MUCH OF WED WILL HAVE THE PSBLY OF EITHER SHRA/TSTM ACTIVITY. BY WED AFTN...MUCH OF THE AREA WILL BE UNDER SOME RISK OF TSTMS...ESPC THE I-95 CRDR BY EVNG. THIS ACTIVITY WILL GRADLY PUSH OFF THE MID ATLNC COAST EARLY THURS. DRY WX WILL RETURN FOR MUCH OF THURS AND INTO FRI. THE WEEKEND LOOKS TO BE ACTIVITY AGAIN W/ SCTD TSTMS PSBLE INTO EARLY NEXT WEEK...W/ A PSBLE COLD FRONTAL PASSAGE ON MON. && .MARINE... NOP PROB WIND WISE TDA-TNGT. AFTN AND EVE TSTMS WL BE THE BIGGEST PROBS FOR MARINERS. WINDS ON WED MAY APRCH SCA CRIT W/ BRIEF PERIODS OF S/RLY CHANNELING FROM AN APRCHNG UPPER LOW PRES SYSTEM. TSTM ACTIVITY WILL BE THE MAIN CONCERN GOING INTO WED AFTN/EVNG. LITTLE CONCERN FOR THE END OF THE WEEK...THO ANOTHER UPPER DISTURBANCE WILL CROSS THE REGION THIS WEEKEND. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ PRODUCTS...WOODY!/GMS md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 259 PM EDT MON JUL 21 2008 .SYNOPSIS... HIGH PRESSURE WILL MOVE OFFSHORE TONIGHT. A COLD FRONT WILL BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS TOMORROW AND WEDNESDAY. THIS FRONT WILL STALL OUT JUST TO OUR SOUTH THURSDAY...AND INCH NORTHWARD TOWARD THE END OF THE WEEK. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... WATER VAPOR LOOP SHOWS A RIDGE ACROSS THE CENTRAL CONUS...WITH AN UPPER LOW OVER QUEBEC. TWO SHORTWAVES WERE ADVANCING FROM THE UPPER MIDWEST...THE LEAD WAVE NEARING THE LOWER GREAT LAKES...WITH THE TRAILING WAVE ROTATING AROUND THE TROUGH FROM CANADA. TROPICAL STORM CRISTOBAL IS MOVING OUT TO SEA. ACARS 400-250MB WIND OBSERVATIONS SHOW A 80-110KT JET FROM THE UPPER MIDWEST EAST NORTHEAST OVER THE UPPER GREAT LAKES AND THE CANADIAN MARITIMES. 11Z SURFACE ANALYSIS PLACED TROPICAL STORM CRISTOBAL OFF THE SOUTHERN VIRGINIA COAST. A TROUGH WAS LOCATED IN THE LEE OF THE SOUTHERN APPALACHIANS. THE NEXT FRONTAL ZONE WAS NEARLY STATIONARY AND STRETCHED FROM THE NORTHERN PLAINS NORTHEAST THROUGH THE CENTRAL GREAT LAKES AND EAST ACROSS NEW ENGLAND. 12Z KIAD RAOB AND KLWX VWP INDICATE NORTHWESTERLY FLOW HAS DEVELOPED IN THE LOWER LEVELS...IN RESPONSE TO CRISTOBAL MOVING NORTHEAST OUT TO SEA. DEWPOINTS HAVE BEEN FALLING FROM WEST TO EAST ACROSS THE FORECAST AREA EARLY THIS AFTERNOON AS A RESULT OF THE DOWNSLOPE FLOW. GOES SATELLITE AND GPS POINT SENSORS INDICATE PRECIPITABLE WATER VALUES HAVE FALLEN TO NEAR AN INCH ACROSS THE REGION. THE NEXT MAXIMA OF MOISTURE IS LOCATED ACROSS THE OHIO VALLEY ASSOCIATED WITH CONVECTION FORMING AHEAD OF A MCV IN NORTHERN OHIO. 12Z NAM/GFS AND THE RUC HAVE NOT HAD ENOUGH CONVECTIVE PRECIPITATION OUTPUT THUS FAR TODAY ACROSS INDIANA AND OHIO. RUC HRRR WRF-ARW3 FROM 15Z WHICH HAD A BETTER REPRESENTATION ACROSS OHIO DOES INDICATE CONVECTION DEVELOPS TO THE EAST ACROSS THE WESTERN FORECAST AREA THIS EVENING. 09Z SREF INDICATING LESS THAN A 50 PERCENT CHANCE OF 500 J/KG OF MUCAPE...AND 50-70 PERCENT CHANCE OF 250 J/KG OF MUCAPE THIS EVENING. THESE VALUES ARE MUCH LOWER THAN LAST NIGHT...SO FOR NOW HAVE INCREASED POPS TO CHANCE ACROSS WESTERN AND NORTHERN ZONES. INVERTED-V SOUNDING MAY ALLOW CONVECTIVE ACTIVITY TO BECOME GUSTY THIS EVENING ACROSS THE MOUNTAINS. DRIER AIR MIXING DOWN THIS AFTERNOON WILL ALLOW TEMPERATURES TO DIP INTO THE UPPER 50S/60S OUT WEST...CLOSER TO 70 MOST LOCATIONS EAST OF INTERSTATE 95 WHERE RICHER DEW POINTS RESIDE. GIVEN ABOVE THOUGHTS...DO NOT THINK PATCHY FOG OUT WEST WILL BE WIDESPREAD ENOUGH OR REDUCE VISIBILITIES BELOW MVFR TO INCLUDE IN FORECAST AT THIS TIME. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... HEIGHTS LOWER TOMORROW AS SUBSIDENCE FROM CRISTOBAL MOVES WELL TO OUR NORTHEAST. THIS SHOULD ENHANCE THE LEE TROUGH...INCREASING MOISTURE ONCE AGAIN PARTICULARLY ACROSS THE EASTERN ZONES. THE LEE TROUGH AND EMBEDDED WAVES WITHIN MEAN FLOW ALOFT MAY SERVE AS TRIGGERS FOR CONVECTIVE DEVELOPMENT DURING THE MID TO LATE AFTERNOON. WITH 09Z SREF INDICATING A 50-70 PERCENT CHANCE OF 1000 J/KG OF MLCAPE...AND 30KT OF EFFECTIVE SHEAR (ESPECIALLY ACROSS NORTHERN ZONES)...CONVECTION MAY BECOME ORGANIZED AND POSE A THREAT OF DAMAGING WINDS AND LARGE HAIL. THERMAL RIDGE SLIDES TO THE SOUTHEAST TOMORROW...WHICH SHOULD SUPPORT SLIGHTLY COOLER TEMPERATURES ACROSS THE WESTERN AND NORTHERN FORECAST AREA. HEAT AND HUMIDITY ARE RETAINED EAST OF INTERSTATE 95...WHERE THE HEAT INDEX MAY NEAR 100 DEGREES. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... INITIALIZATION ISSUES IN THE 1ST 24 HRS WL IMPACT GDNC SOLNS AT LATER RANGES. THAT ERODES CONFIDENCE OUT OF THE GATE. GFS ALSO SUFFERING FM TYPICAL GRIDSCALE FEEDBACK ISSUES. BUT...IN THE BIGGER PICTURE...THERE ARE A CPL OF FEATURES WHICH FCST WL RIDE UPON. FIRST WL BE TRACKING MCV AND ITS SFC REFLECTION ACRS CWFA TMRW NGT...AND 2NDLY TRACKING H5 TROF AXIS PIVOTING SWD FM DVLPG UPR LOW WED. ALTHO AMS WL BE MARGINALLY UNSTBL...EACH OF THESE FEATURES WL BE CAPABLE OF INITIATING ITS OWN CNVCTN. IN ADDITION...AMS WONT HV THE SUBSIDENCE THAT WAS PRESENT PAST CPL DAYS. GOING FCST PRETTY MUCH HAS THIS CVRD. CHGS TO GRIDS TMRW NGT WL BE MINOR. POPS DO INCR IN THE EVNG AS VORT SLIDES THRU. HARD TO FIND OPERATIONAL GDNC TO SUPPORT IT...BUT MOS DOES REFLECT THIS THINKING PER HIER 3RD PD POPS. IN A BROADER PERSPECTIVE...SO DOES 09Z SREF... THO POP OUTPUT SEEMS A BIT MEAGER. UNLIKE YDA...SHUDNT BE MUCH OF A CAP IN PLACE...AND THINK ACTVTY WL BE ABLE TO SUSTAIN ITSELF...AT LEAST INTO THE EVNG. TRENDS SO SCALE DWNWD AFTR MIDNGT AS THE DIURNAL CYCLE FINALLY PREVAILS. BUT...THAT WL PLACE A SFC CNVGNC BNDRY ACRS CWFA WHEN UPR TROF PIVOTS THRU. SOME SPREAD STARTS CREEPING INTO H5 HGT ENS PLOTS... AS OP GDNC NOT REAL CERTAIN WHEN/WHERE TO PLACE THIS ACTVTY. WHENEVER IT DOES OCCURS...IT SHUD RE-ENERGIZE CNVCTN...AND MAY ACTUALLY BE ABLE TO SUPPORT SOME STRONGER STORMS. HV SUBSEQUENTLY RAISED POPS FOR WED...SPCLY E OF BLURDG...WHERE LIKELY POPS NOW IN PLACE. THAT ROUND SHUD WORK OFFSHORE WED EVNG...SHOVING SFC FRNT S/E OF CWFA...AND ALLWG SLGTLY COOLER/DRIER AIR IN. HVNT STRAYED TOO FAR FROM MOS TEMPS...WHICH DONT REFLECT MUCH OF A SPREAD FM EACH OTR OR FM GOING FCST. DUE TO INHERENT UNCERTAINTIES IN THE DAY 2-3 FCST...CONFIDENCE IN THE XTNDD FCST REMAINS LOW. THE KEY STICKING PT REMAINS WHAT TO DO WITH THE STALLED QSTNRY BNDRY. PRIND HIPRES FM GRTLKS SHUD HV A GREATER INFLUENCE...AT LEAST FOR PTMC HIGHLANDS. BUT...REEMERGENCE OF H5 TROF A BIT TRBLG. WHENEVER TROF AXIS SWINGS THRU...COMBINED WITH RTN FLOW...CWFA SHUD BE SET FOR MORE TSRA. THAT SHUD BE TWD THE WKND...BUT TOO MANY UNRESOLVED VRBLS TO ACCURATELY DEPICT THESE DETAILS. SO...THIS FCST WL FEATURE CHC TSRA ALL BUT PTMC HIGHLANDS FRI...AND CHC TSRA AREAWIDE SAT-MON. HV CONFINED TIMING TO DIURNAL MAX...AFTN-EVE. GIVEN LWR HGTS...TEMPS WL BE NEAR CLIMO...W/ A DECENT AMT OF CLDCVR LURKING. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... OUTSIDE CHANCE FOR CONVECTION THIS EVENING AS MCV ACROSS OHIO MOVES INTO PENNSYLVANIA. REPRESENTED THIS AS A CB GROUP...SINCE DID NOT HAVE CONSISTENT GUIDANCE TO BE CONFIDENT ENOUGH TO INCLUDE IN TAFS AT THIS TIME. OTHERWISE...DECOUPLING SHOULD DIMINISH WIND THIS EVENING. DEW POINTS MIXED OUT DURING THE AFTERNOON...AND THOUGH THEY SHOULD RECOVER...DO NOT ANTICIPATE MORE THAN PATCHY MVFR FOG WEST OF THE BLUE RIDGE AT THIS TIME. CONVECTIVE CHANCES BEGIN TO INCREASE TOMORROW AFTERNOON AS HEIGHTS FALL ALOFT...BUILDING INSTABILITY AND DEEP LAYER SHEAR FOR ORGANIZATION. FLGT RESTRICTIONS PSBL INVOF TSRA TUE-WED. TSRA DURATION LIKELY TO BE SHORT...BUT PD OF RISK LONGER. STORMS MAY REINITIATE THU AFTN-EVE DCA-BWI. && .MARINE... NORTHWEST FLOW GRADUALLY WEAKENS...BEFORE BECOMING SOUTHERLY THIS EVENING. CONVECTIVE CHANCES BEGIN TO INCREASE TOMORROW AFTERNOON AS HEIGHTS FALL ALOFT...BUILDING INSTABILITY AND DEEP LAYER SHEAR FOR ORGANIZATION. SPECIAL MARINE WARNINGS MAY BECOME NECESSARY DURING THE AFTERNOON AND EVENING. NO FLAGS ANTICIPATED IN LATER PDS EITHER...BUT TSRA STILL ARE. XPCT LCLLY HIER WNDS/WVS AS WELL AS LTNG TUE-WED AS BNDRY EEKS THROUGH...SUPPORTED BY UPR LVL IMPULSES. STORMS MAY REINITIATE INVOF SAME BNDRY TO THE S THU AND FRI AFTN-EVE. SMW/S WL BE PSBL DURING THIS TIME FRAME. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...HTS NEAR TERM...ROGOWSKI SHORT TERM...ROGOWSKI LONG TERM...HTS AVIATION...ROGOWSKI/HTS MARINE...ROGOWSKI/HTS md AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1050 PM EDT TUE JUL 22 2008 .SYNOPSIS... WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH INTO THE CENTRAL GREAT LAKES AND A RIDGE FROM THE SRN ROCKIES TO MANITOBA AND HUDSON BAY RESULTING INT NRLY FLOW THROUGH THE UPPER GREAT LAKES. AT THE SFC...HIGH PRES EXTENDED FROM HUDSON BAY AND NRN ONTARIO INTO WITH ACYC NNE FLOW ACROSS UPPER MICHIGAN. SOME ISOLD SHRA/TSRA HAVE DEVELOPED OVER W AND SRN UPPER MI...WELL DOWNSTREAM FROM STABILIZING INFLUENCE OF LAKE SUPERIOR WHERE CAPE VALUES CAPE VALUES HAD CLIMBED TO AROUND 500 J/KG. .SHORT TERM...(TONIGHT AND WEDNESDAY) AFTER THE SHAR/TSRA FADE WITH DIURNAL COOLING AND INFLUX OF DRIER AIR FROM THE NORTH...EXPECT MOSTLY CLEAR SKIES TONIGHT. WINDS OVER THE WEST HALF SHOULD BE LIGHT ENOUGH...AOB 5 KT...FOR RADIATIONAL COOLING TO ALLOW TEMPS TO DROP INTO THE UPPER 40S. 11C TO 12C 850 MB TEMPS SUPPORT MAX READINGS INTO THE MID AND UPPER 70S INLAND WITH COOLER READINGS ALONG LAKE SUPERIOR. DRY AIR OVER THE REGION ALONG WITH MID LEVEL SUBSIDENCE/WARMING WILL KEEP AREA DRY WITH ONLY FEW/SCT CU DEVELOPING. .LONG TERM (WEDNESDAY NIGHT THROUGH NEXT TUESDAY)... BASED ON HPC CONFIDENCE AND GOOD AGREEMENT IN GFS ENS AND ECMWF...WENT WITH A BLEND OF THOSE TWO MODELS FOR MOST OF THE EXTENDED PART OF THE FORECAST...BUT DID USE A BLEND OF THE NAM DURING THE EARLY PERIODS. UPPER TROUGH CENTERED OVER THE ONTARIO AND QUEBEC BORDER...WILL CONTINUE TO SLOWLY DRIFT TO THE NORTHEAST DURING THE FIRST PART OF THE EXTENDED PERIOD. WITH UPPER MI BEING ON THE WRN SIDE OF THE TROUGH AND UNDER A WEAK RIDGE...HIGH PRESSURE WILL BE OVER THE REGION FOR THE WED NIGHT AND FIRST PART OF THURS. MOSTLY CLEAR SKIES SHOULD ALLOW LOWS TO BE BELOW NORMAL. STAYED TOWARDS THE MOS GUIDANCE...BUT THEY COULD BE TWEAKED DOWN A BIT IN SOME OF THE COOLER SPOTS. WEAK UPPER WAVE AND SFC LOW COMING OUR OF THE NRN ROCKIES ON WED...EJECTING FROM CURRENT TROUGH OVER THE PACIFIC NW...WILL APPROACH THE REGION ON THURS. THIS WILL BRING THE BEST CHANCE FOR RAIN DURING THE THURS NIGHT THROUGH FRI NIGHT TIMEFRAME. GFS AND ECMWF IN GOOD AGREEMENT WITH THE POSITION OF THE WEAK LOW...AROUND 1004MB...OVER THE LAKE WINNIPEG REGION AT 12Z ON THURS. THIS LOW WITH THEN SLOWLY SHIFT NE TOWARDS SRN HUDSON BAY BY 12Z SAT...WHILE DRAGGING A COLD FRONT EASTWARD ACROSS UPPER MI ON FRIDAY. DIDN`T MAKE ANY MAJOR CHANGES TO THE PCPN CHANCES FOR THURS...AS EXISTING CHANCE OVER THE FAR WRN PART OF LK SUPERIOR LOOKED GOOD. NAM IS A LITTLE SLOWER WITH THE START OF THE PCPN ON THURS...DUE TO DRIER AIR HOLDING ON A LONGER...BUT FELT THE EXISTING CHANCE POPS MATCHED UP WELL. INTO THURS NIGHT...ONLY EXPECT A FEW SHOWERS...AND POSSIBLY SOME RUMBLES OF THUNDER. EXPECT THE PCPN TO BE OVER THE WRN HALF OF THE CWA...AS ELEVATED H850 CAPE IS AROUND 500-800 J/KG AND SHOWALTER AROUND -2C...MOVES E INTO THE AREA ALONG THE H850 FRONT. WITH THE LIMITED INSTABILITY AND LACK OF SHEAR...ONLY ABOUT 25-30KT 0-6KM BULK SHEAR...DON`T REALLY EXPECT TO SEE ANYTHING SEVERE. FRIDAY LOOKS LIKE A LITTLE BETTER CHANCE OF SEEING SEVERE THUNDERSTORMS...WITH THE BEST CHANCES S AND W OF A LINE FROM IWD TO MQT TO ISQ. IN THIS AREA...BULK SHEAR VALUES ARE SLIGHTLY IMPROVED...30-35KTS...AND MLCAPE VALUES ARE IN THE 500-1000 J/KG RANGE. WITH THE FRONTAL PASSAGE DURING THE AFTN...DO EXPECT TO SEE SOME THUNDERSTORMS DEVELOPING...BUT BELIEVE THERE WILL ONLY BE ISOLATED STRONG TO SEVERE STORMS. WAVE WITH THE LOW WILL MERGE AND STRENGTHEN THE UPPER TROUGH OVER SWRN QUEBEC ON FRIDAY NIGHT...WITH UPPER TROUGH ALSO OFF THE W COAST OF NOTAM. THIS WILL BRING NW FLOW TO THE REGION FOR THE REST OF THE WEEKEND AND FIRST PART OF NEXT WEEK...AS RIDGE BUILDS OVER CNTL NOTAM. LINGERING MOISTURE WILL ROTATE AROUND THE UPPER LOW FOR THE FIRST PART OF THE WEEKEND. WOULD NOT BE SURPRISED TO SEE SOME VERY LIGHT RAIN OR DRIZZLE BEHIND THE COLD FRONT ON SAT AND SAT NIGHT...ESPECIALLY OVER THE ERN TWO THIRDS OF LK SUPERIOR AND LAND LOCATIONS NEAR THERE...AS MODELS HINT AT A WEAK SHORTWAVE ROTATING THROUGH. CONTEMPLATED ADDING POPS IN OVER THE NRN PORTION OF UPPER MI...BUT SINCE THE COVERAGE WOULD BE PRETTY LIMITED AND THE PCPN WILL BE LIGHT...ONLY ADDED A SLIGHT CHANCE FOR LK SUPERIOR LOCATIONS. ALSO BUMPED UP THE CLOUD COVER FOR THAT TIME PERIOD. WITH THE UPPER LOW FINALLY SHIFTING TO THE E ON SUN...HIGH PRESSURE WILL MOVE OVER THE REGION FOR THE REST OF THE EXTENDED PERIOD. THEREFORE...DIMINISHED CLOUD COVER ACROSS THE AREA AND WENT WITH NEAR NORMAL TEMPS. .AVIATION (FOR THE 00Z TAF ISSUANCE)... EXPECT VFR CONDITIONS THIS FCST PD WITH DRY HI PRES BLDG TOWARD LK SUP. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... A HIGH PRESSURE RIDGE FROM HUDSON BAY INTO THE UPPER GREAT LAKES WILL BUILD SOUTH OVER LAKE SUPERIOR ON WEDNESDAY AND THEN INTO THE LOWER GREAT LAKES ON THURSDAY. AS THIS HIGH DRIFTS INTO THE MID ATLANTIC STATES ON FRIDAY...A LOW PRESSURE TROUGH WILL MOVE INTO THE UPPER GREAT LAKES. LOOK FOR THIS TROUGH TO DRIFT INTO THE CENTRAL GREAT LAKES ON SATURDAY IN ADVANCE OF HIGH PRESSURE BUILDING TOWARD THE NORTHERN PLAINS. OTHERWISE...WINDS WILL BE NO GREATER THAN 20 KNOTS THROUGH THE END OF THE WEEK. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...JLB LONG TERM...SRF AVIATION...JV MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 800 PM EDT TUE JUL 22 2008 LATEST UPDATE...AVIATION... .SYNOPSIS...(215 PM EDT TUE JUL 22 2008) SHOWERS AND SCATTERED THUNDERSTORMS THIS AFTERNOON WILL DISSIPATE EARLY THIS EVENING. THE STRONGEST STORMS COULD CONTAIN SMALL HAIL AND GUSTY WINDS. HIGH PRESSURE BUILDING SOUTH FROM CANADA WILL BRING DRY WEATHER THROUGH FRIDAY. DAYTIME TEMPERATURES WILL BE NEAR NORMAL WITH OVERNIGHT TEMPERATURES A BIT BELOW NORMAL. && .SHORT TERM...(215 PM EDT TUE JUL 22 2008) (TODAY THROUGH THURSDAY MORNING) SFC TROF AND H5 SHORT WAVE TOUCHING OFF SHOWERS AND A FEW THUNDERSTORMS ACROSS THE NORTHERN HALF OF THE CWA ATTM. EXPECT THIS AREA TO CONTINUE TO EXPAND UNTIL ABOUT 22Z AND THEN DECAY AS IT MOVES SOUTHWARD. LATEST RUC DEVELOPS 500-1000 J/KG OF MIXED LAYER CAPE ACROSS CENTRAL ZONES BY 21Z. SHEAR VALUES ARE VERY WEAK SO NOT EXPECTING VERY MUCH ORGANIZATION. SO...NOT EXPECTING SEVERE ATTM...BUT SMALL HAIL...WIND GUSTS TO 40 MPH AND A QUICK INCH OF RAIN IS POSSIBLE WITH THE STRONGEST STORMS. HIGH PRESSURE BUILDS SOUTH FOR WED WITH GRADUALLY FALLING DEWPOINTS...EXPECT NOTHING MORE THAN SCT/BKN FAIR WEATHER CUMULUS WED AFTN. SOME POTENTIAL FOR VALLEY/RIVER FOG THU AM WITH LIGHT WINDS. && .LONG TERM...(310 PM EDT TUE JUL 22 2008) (THURSDAY THROUGH TUESDAY) UPPER LOW IS EXPECTED TO BE EAST OF THE CWFA BY THE BEGINNING OF THE LONG TERM ON THU MORNING. SHORT WAVE RIDGING WILL BE UPSTREAM OF THE AREA AND SLOWLY BUILDING OVER THE CWFA THROUGH THU NIGHT. THIS SETUP WILL BRING MILD TEMPS AND DRY WEATHER THROUGH THU NIGHT. THE GFS DOES BRING AN AREA OF RAIN THROUGH THE CWFA THU NIGHT. THIS LOOKS TO BE THE RESULT OF CONVECTIVE FEEDBACK IN THE MODEL...AND HAS BEEN IGNORED FOR NOW. A SHORT WAVE TROUGH THAT IS EXPECTED TO MOVE ONSHORE OVER THE PACIFIC NW TOMORROW MORNING WILL TRAVERSE THE U.S./CANADIAN BORDER TO LAKE SUPERIOR BY FRI. THIS SHORT WAVE ALONG WITH ADDITIONAL SHORT WAVE ENERGY DIVING SOUTH OUT OF CANADA WILL HELP BRING A COLD FRONT ON FRI NIGHT. AHEAD OF THIS FRONT...WARMER AND MORE MOIST AIR WILL ADVECT INTO THE AREA...AND ALLOW FOR SOME INSTABILITY TO BUILD. A FEW SHOWERS AND STORMS WILL BE POSSIBLE ON FRI WITH THE BETTER CHC LIKELY COMING ON FRI EVENING WITH THE FRONT. THE THREAT OF PCPN WITH THIS FRONT IS NOT IMPRESSIVE AS MOST OF THE UPPER ENERGY REMAINS NORTH OF THE CWFA. MOST OF THE PCPN THREAT WILL END AS THE FRONT MOVES THROUGH FRI NIGHT. SOME LINGERING SHOWERS COULD BE FOUND EARLY SAT. MODELS ARE IN FAIRLY GOOD AGREEMENT IN KEEPING THE UPPER JET AND CYCLONIC FLOW JUST NORTH OF THE CWFA THROUGH THE WEEKEND. WITH THIS IN MIND...WE WILL MAINTAIN THE GOING DRY FCST. IF THIS JET SINKS SOUTH JUST A LITTLE MORE...WE WOULD BE LOOKING AT THE POTENTIAL FOR SOME DIURNALLY DRIVEN SHOWERS/STORMS FOR SUN. THE UPPER LOW SHOULD MOVE OUT...AND UPPER RIDGING WILL MOVE IN FOR EARLY NEXT WEEK BRINGING DRY AND MILD CONDITIONS TO THE AREA. && .MARINE...(1200 PM EDT TUE JUL 22 2008) WEAK LOW PRESSURE TROF LOCATED NEAR PENTWATER WILL SINK SOUTH OF LAKE MICHIGAN BY LATE AFTERNOON. WINDS ARE GENERALLY ONSHORE SOUTH AND NORTH BEHIND THE TROF. GLERL WAVE MODEL CONSISTENT IN SHOWING AREA OF 4-6 FOOT WAVES DEVELOPING OVER CENTRAL LAKE WITH NORTH WINDS BEHIND TROF. THE WAVES MOVE ONSHORE EXTREME SE PORTION THIS EVENING. A SMALL CRAFT ADVISORY MAY BE NEEDED ON WED SOUTH OF WHITEHALL AGAIN WITH GOOD FETCH OF N-NW WINDS OF 15 KTS CONTINUING TO DEVELOP WAVES APPROACHING 5 FEET IN THE AFTERNOON. && .AVIATION...(800 PM EDT TUE JUL 22 2008) UPPER TROUGH IS LOCATED OVERHEAD THIS EVENING...WITH A SHORTWAVE CURRENTLY SWINGING THROUGH THE FORECAST AREA. SHORTWAVE TOUCHED OFF SHOWERS AND THUNDERSTORMS EARLIER THIS AFTERNOON...WHICH HAVE FOR THE MOST PART COME TO AND END. THERE ARE SOME LINGERING SHOWERS ACROSS SOUTHWEST LOWER MICHIGAN...BUT SUSPECT THIS ACTIVITY WILL CONTINUE TO FADE THROUGH THE COURSE OF THE EVENING. MAIN FORECAST ISSUE IS THE LOWER CLOUDS THAT HAVE DEVELOPED IN THE WAKE OF THE AFTERNOON SHOWERS AND STORMS. MVFR CEILINGS BETWEEN 1000 AND 3000 FT EXIST FROM KGRR TO KLAN AND POINTS SOUTH. FEEL THESE CEILINGS WILL PUSH SOUTH AND DISSIPATE THROUGH THE COURSE OF THE NEXT FEW HOURS. LOOKING FOR A VFR NIGHT FOR THE MOST PART WITH A LIGHT NORTH WIND. EXPECT ANY FOG TO BE HELD AT BAY TONIGHT WITH FAIRLY STIFF NORTH WINDS JUST OFF THE DECK (15-25 KTS AT 1000 FT). ON WEDNESDAY... EXPECTING SCT-BKN CUMULUS TO DEVELOP WITH BASES AROUND 5000 FT. && .HYDROLOGY...(200 PM EDT TUE JUL 22 2008) SLIGHT CHANCE OF SOME LOCALIZED FLOODING WITH MAX T-STORM AMOUNTS OF 1.5 INCHES. MOST LOCATIONS WILL SEE 0.25 INCHES OR LESS THROUGH THIS EVENING. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...SMALL CRAFT ADVISORY ST. JOSEPH TO WHITEHALL FROM 18Z THIS AFTN THROUGH 07Z TONIGHT. && $$ SYNOPSIS: COBB SHORT TERM: COBB LONG TERM: NJJ MARINE: COBB AVIATION: DUKE HYDROLOGY: COBB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 215 PM EDT TUE JUL 22 2008 LATEST UPDATE...AVIATION...HYDROLOGY...SYNOPSIS...SHORT TERM... .SYNOPSIS...(215 PM EDT TUE JUL 22 2008) SHOWERS AND SCATTERED THUNDERSTORMS THIS AFTERNOON WILL DISSIPATE EARLY THIS EVENING. THE STRONGEST STORMS COULD CONTAIN SMALL HAIL AND GUSTY WINDS. HIGH PRESSURE BUILDING SOUTH FROM CANADA WILL BRING DRY WEATHER THROUGH FRIDAY. DAYTIME TEMPERATURES WILL BE NEAR NORMAL WITH OVERNIGHT TEMPERATURES A BIT BELOW NORMAL. && .SHORT TERM...(215 PM EDT TUE JUL 22 2008) (TODAY THROUGH THURSDAY MORNING) SFC TROF AND H5 SHORT WAVE TOUCHING OFF SHOWERS AND A FEW THUNDERSTORMS ACROSS THE NORTHERN HALF OF THE CWA ATTM. EXPECT THIS AREA TO CONTINUE TO EXPAND UNTIL ABOUT 22Z AND THEN DECAY AS IT MOVES SOUTHWARD. LATEST RUC DEVELOPS 500-1000 J/KG OF MIXED LAYER CAPE ACROSS CENTRAL ZONES BY 21Z. SHEAR VALUES ARE VERY WEAK SO NOT EXPECTING VERY MUCH ORGANIZATION. SO...NOT EXPECTING SEVERE ATTM...BUT SMALL HAIL...WIND GUSTS TO 40 MPH AND A QUICK INCH OF RAIN IS POSSIBLE WITH THE STRONGEST STORMS. HIGH PRESSURE BUILDS SOUTH FOR WED WITH GRADUALLY FALLING DEWPOINTS...EXPECT NOTHING MORE THAN SCT/BKN FAIR WEATHER CUMULUS WED AFTN. SOME POTENTIAL FOR VALLEY/RIVER FOG THU AM WITH LIGHT WINDS. && .LONG TERM...(400 AM EDT TUE JUL 22 2008) (THURSDAY NIGHT THROUGH MONDAY) THE MAIN FEATURE IN THE EXTENDED PERIOD WILL BE A SFC COLD FRONT ASSOCIATED WITH THE NEXT UPR LOW MOVING EAST ACROSS SRN CANADA. MODELS ARE IN FAIR AGREEMENT WITH THE TIMING OF THIS FRONT... AND ARE CURRENTLY PROGGING IT TO COME THROUGH THE GRTLKS REGION ON FRIDAY NIGHT AND SATURDAY. HAVE MAINTAINED CHC POPS FOR SHOWERS AND TSTMS ON FRIDAY AND FRIDAY NIGHT IN SW FLOW WAA PATTERN PRECEDING THE FRONT... AND HAVE ADDED POPS FROM GRR SOUTH AND EAST FOR 12Z-18Z SATURDAY. NW FLOW AFTER FROPA SATURDAY SHOULD DRY THINGS OUT FROM WEST TO EAST. THE WX PATTERN FOR SUNDAY AND MONDAY WILL FEATURE NW FLOW ALOFT (UPR LOW OVER QUEBEC)... WITH SURFACE RIDING BUILDING SE FROM THE NRN PLAINS. THIS SHOULD BE A PLEASANT/DRY PERIOD FOR SW MI WITH TEMPS AT OR JUST A TAD BELOW NORMAL. && .MARINE...(1200 PM EDT TUE JUL 22 2008) WEAK LOW PRESSURE TROF LOCATED NEAR PENTWATER WILL SINK SOUTH OF LAKE MICHIGAN BY LATE AFTERNOON. WINDS ARE GENERALLY ONSHORE SOUTH AND NORTH BEHIND THE TROF. GLERL WAVE MODEL CONSISTENT IN SHOWING AREA OF 4-6 FOOT WAVES DEVELOPING OVER CENTRAL LAKE WITH NORTH WINDS BEHIND TROF. THE WAVES MOVE ONSHORE EXTREME SE PORTION THIS EVENING. A SMALL CRAFT ADVISORY MAY BE NEEDED ON WED SOUTH OF WHITEHALL AGAIN WITH GOOD FETCH OF N-NW WINDS OF 15 KTS CONTINUING TO DEVELOP WAVES APPROACHING 5 FEET IN THE AFTERNOON. && .AVIATION...(200 PM EDT TUE JUL 22 2008) SHOWERS AND SCATTERED THUNDERSTORMS THROUGH THE AFTERNOON. SMALL HAIL AND NORTHERLY WIND GUSTS TO 40 KTS ARE POSSIBILITIES WITH STRONGEST STORMS. TOPS WILL GENERALLY STAY BELOW 30 KFT. OUTLOOK FOR VFR ON WED WITH SOME SFC WIND GUST TO 20 KTS. && .HYDROLOGY...(200 PM EDT TUE JUL 22 2008) SLIGHT CHANCE OF SOME LOCALIZED FLOODING WITH MAX T-STORM AMOUNTS OF 1.5 INCHES. MOST LOCATIONS WILL SEE 0.25 INCHES OR LESS THROUGH THIS EVENING. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...SMALL CRAFT ADVISORY ST. JOSEPH TO WHITEHALL FROM 18Z THIS AFTN THROUGH 07Z TONIGHT. && $$ SYNOPSIS: COBB SHORT TERM: COBB LONG TERM: MEADE MARINE: COBB AVIATION: COBB HYDROLOGY: COBB mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 145 PM EDT TUE JUL 22 2008 UPDATED FOR 18Z AVIATION DISCUSSION .UPDATE... MAIN FCST CONCERN IS POTENTIAL FOR SHRA/TSRA SOUTH THIS AFTERNOON. THE -SHRA OVER WRN UPPER MI SUPPORTED BY A WEAK SHORTWAVE TROUGH HAVE DIMINISHED AND SLID S OF THE CWA. HOWEVER...FCST AND MODIFIED OBSERVED SOUNDINGS SUGGEST THAT AFTERNOON HEATING WITH TEMPS INTO THE MID 70S AND DEWPOINTS IN THE MID 50S WOULD GIVE MLCAPE VALUES NEAR 500 J/KG. WITH RELATIVELY STEEP 700-500 MB LAPSE RATES NEAR 7 C/KM...SOME ISOLD SHRA/TSRA ARE STILL POSSIBLE OVER THE SOUTH...AWAY FROM STABILIZING INFLUENCE OF FLOW OFF OF LAKE SUPERIOR. WITH ONLY MARGINAL INSTABILITY...FREEZING LEVEL AROUND 11K FT...AND WEAK SHEAR...ONLY SMALL HAIL WOULD BE EXPECTED WITH ANY STRONGER TSRA. .DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST PACKAGE ARE THE TEMPERATURES TODAY AND TONIGHT. WATER VAPOR AND RUC SHOWING A CLOSED LOW OVER QUEBEC WITH WEAK SHORTWAVE WRAPPING THROUGH ITS BASES. THESE ARE OVER EASTERN LAKE SUPERIOR AND NORTHERN ONTARIO. A LARGE RIDGE IS BUILDING OVER THE HIGH PLAINS AND EXTENDING NORTHEAST INTO THE CANADIAN PRAIRIE. ANOTHER LONGWAVE TROUGH DIGGING OVER THE PACIFIC NORTHWEST. SURFACE ANALYSIS DEPICTS A HIGH OVER HUDSON BAY AND ONTARIO. A LOW DEEPENING OVER THE SOUTHWEST SASKATCHEWAN. A STATIONARY FRONT STRETCHES FROM THE CENTRAL PLAINS ACROSS THE OHIO RIVER VALLEY TO NEW ENGLAND. THIS ESSENTIALLY CUTS OFF MOISTURE FROM THE GULF AND OCEAN. THE MID LEVEL RIDGE WILL SHIFT INTO THE NORTHERN PLAINS AND MANITOBA TODAY...WHILE THE LOW CONTINUES TO SPIN OVER QUEBEC AND EASTERN ONTARIO. THE LAKE SUPERIOR SHORTWAVE WILL SHIFT EAST...WHILE THE ONTARIO SHORTWAVE SWEEPS THROUGH WISCONSIN. THE SURFACE HIGH WILL CONTINUE OVER HUDSON BAY AND BLANKETING NORTHERN ONTARIO AND MUCH OF THE UPPER GREAT LAKES. DRY AIR ACCOMPANYING THE SURFACE RIDGE WILL KEEP THE AIR MASS DRY OVER THE AREA. THE MID LEVEL QUEBEC LOW WILL BACK INTO EASTERN ONTARIO WHILE DEEPENING TONIGHT. SHORTWAVES WILL SWEEP AROUND THE BASE OF THIS LOW AND INTO LOWER MICHIGAN AND THE LOWER GREAT LAKES. THE NORTHERN PLAINS RIDGE WILL EDGE INTO EASTERN DAKOTAS. SHORTWAVES WILL BE APPROACHING THE APEX OF THIS RIDGE. THE SURFACE RIDGE WILL EXPAND AND BLANKET THE UPPER GREAT LAKES...UPPER MISSISSIPPI RIVER VALLEY AND ONTARIO...AND MUCH OF HUDSON BAY. CLOUD COVER DUE TO THE WEAK SHORTWAVE AND A NORTHERLY FLOW WILL LIMIT HEATING TODAY. WILL GO WITH TEMPERATURES IN THE MID 70S WHICH WILL BE A LITTLE WARM THAN YESTERDAY. THE MID LEVEL LOW WILL BACK INTO LAKE HURON AS THE RIDGE PUSHES INTO WESTERN ONTARIO AND THE UPPER MISSISSIPPI RIVER VALLEY WEDNESDAY AND WEDNESDAY NIGHT. SHORTWAVES WILL CONTINUE TO PUSH INTO THE RIDGE BUT WILL REMAIN OVER THE DAKOTAS AND MANITOBA. THE SURFACE RIDGE WILL REMAIN OVER ONTARIO AND THE UPPER GREAT LAKES. MEANWHILE THE SURFACE LOW OVER SASKATCHEWAN WILL SHIFT INTO CENTRAL MANITOBA. FRONTOGENESIS WITH THIS LOW WILL PRODUCE A FRONT OVER THE DAKOTAS AND MANITOBA. THE MID LEVEL LOW WILL EDGE INTO WESTERN QUEBEC ON THURSDAY WHILE THE RIDGE CONTINUES OVER CENTRAL ONTARIO WHILE WEAKENING. A WEAK SHORTWAVE MOVING THROUGH THE RIDGE WILL SHIFT INTO THE WESTERN U.P. ANOTHER MID LEVEL WILL DEVELOP OVER NORTHERN MANITOBA. THE SURFACE LOW WILL MOVE TO JUST NORTHEAST OF LAKE WINNIPEG DRAGGING THE COLD FRONT INTO WESTERN MINNESOTA. WEAK SHORTWAVE ENERGY AND ISENTROPIC ASCENT AHEAD OF THE APPROACHING COLD FRONT WILL GENERATE A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS OVER THE FAR WESTERN U.P. LATE ON THURSDAY. THE MID LEVEL CLOSED LOW WILL REMAIN JUST EAST OF HUDSON BAY THURSDAY NIGHT. THE MID LEVEL LOW OVER MANITOBA WILL EDGE INTO WESTERN ONTARIO. THE RIDGE SEPARATING THESE WILL WEAKEN EVEN MORE AS IT SHIFT OVER THE FORECAST AREA. THE COLD FRONT AND ACCOMPANYING LOW WILL EDGE INTO THE UPPER MISSISSIPPI RIVER VALLEY. ISENTROPIC ASCENT AHEAD OF THE FRONT WILL LEAD TO A CHANCE OF SOME SHOWERS AND THUNDERSTORMS DEVELOPING OVER THE AREA. THE LOW OVER MANITOBA WILL MOVE INTO NORTHWEST ONTARIO ON FRIDAY. SHORTWAVES WRAPPING THROUGH THE BASE OF THIS LOW ALONG WITH THE COLD FRONT WHICH WILL MOVE INTO WESTERN LAKE SUPERIOR WILL CONTRIBUTE TO THE CHANCE OF SHOWERS AND THUNDERSTORMS CONTINUING ACROSS THE FORECAST AREA. THE COLD FRONT AND THE SHORTWAVE ENERGY WILL REACH KANJ BY SUNRISE SATURDAY MORNING. DRY AIR WILL MOVE OVER THE AREA BRINGING FAIR WEATHER TO THE AREA FOR WEEK END. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... EXPECT VFR CONDITIONS THIS FCST PD WITH DRY HI PRES BLDG TOWARD LK SUP. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT HIGH PRESSURE OVER HUDSON BAY TO BUILD SOUTH OVER LAKE SUPERIOR ON WEDNESDAY AND THEN INTO THE LOWER GREAT LAKES ON THURSDAY. LINGERING FOG OVER LAKE SUPERIOR WILL DISSIPATE THIS MORNING AS DRY AIR ASSOCIATED WITH THE HIGH CONTINUES TO ADVECT OVER THE LAKE. AS THIS HIGH DRIFTS INTO THE MID ATLANTIC STATES ON FRIDAY...A LOW PRESSURE TROUGH WILL MOVE INTO THE UPPER GREAT LAKES. LOOK FOR THIS TROUGH TO DRIFT INTO THE CENTRAL GREAT LAKES ON SATURDAY IN ADVANCE OF HIGH PRESSURE BUILDING TOWARD THE NORTHERN PLAINS. OTHERWISE...WINDS WILL BE NO GREATER THAN 20 KNOTS THROUGH THE END OF THE WEEK. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...JLB DISCUSSION...DLG AVIATION...JLB MARINE...KC mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1140 AM EDT TUE JUL 22 2008 .UPDATE... MAIN FCST CONCERN IS POTENTIAL FOR SHRA/TSRA SOUTH THIS AFTERNOON. THE -SHRA OVER WRN UPPER MI SUPPORTED BY A WEAK SHORTWAVE TROUGH HAVE DIMINISHED AND SLID S OF THE CWA. HOWEVER...FCST AND MODIFIED OBSERVED SOUNDINGS SUGGEST THAT AFTERNOON HEATING WITH TEMPS INTO THE MID 70S AND DEWPOINTS IN THE MID 50S WOULD GIVE MLCAPE VALUES NEAR 500 J/KG. WITH RELATIVELY STEEP 700-500 MB LAPSE RATES NEAR 7 C/KM...SOME ISOLD SHRA/TSRA ARE STILL POSSIBLE OVER THE SOUTH...AWAY FROM STABILIZING INFLUENCE OF FLOW OFF OF LAKE SUPERIOR. WITH ONLY MARGINAL INSTABILITY...FREEZING LEVEL AROUND 11K FT...AND WEAK SHEAR...ONLY SMALL HAIL WOULD BE EXPECTED WITH ANY STRONGER TSRA. .DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST PACKAGE ARE THE TEMPERATURES TODAY AND TONIGHT. WATER VAPOR AND RUC SHOWING A CLOSED LOW OVER QUEBEC WITH WEAK SHORTWAVE WRAPPING THROUGH ITS BASES. THESE ARE OVER EASTERN LAKE SUPERIOR AND NORTHERN ONTARIO. A LARGE RIDGE IS BUILDING OVER THE HIGH PLAINS AND EXTENDING NORTHEAST INTO THE CANADIAN PRAIRIE. ANOTHER LONGWAVE TROUGH DIGGING OVER THE PACIFIC NORTHWEST. SURFACE ANALYSIS DEPICTS A HIGH OVER HUDSON BAY AND ONTARIO. A LOW DEEPENING OVER THE SOUTHWEST SASKATCHEWAN. A STATIONARY FRONT STRETCHES FROM THE CENTRAL PLAINS ACROSS THE OHIO RIVER VALLEY TO NEW ENGLAND. THIS ESSENTIALLY CUTS OFF MOISTURE FROM THE GULF AND OCEAN. THE MID LEVEL RIDGE WILL SHIFT INTO THE NORTHERN PLAINS AND MANITOBA TODAY...WHILE THE LOW CONTINUES TO SPIN OVER QUEBEC AND EASTERN ONTARIO. THE LAKE SUPERIOR SHORTWAVE WILL SHIFT EAST...WHILE THE ONTARIO SHORTWAVE SWEEPS THROUGH WISCONSIN. THE SURFACE HIGH WILL CONTINUE OVER HUDSON BAY AND BLANKETING NORTHERN ONTARIO AND MUCH OF THE UPPER GREAT LAKES. DRY AIR ACCOMPANYING THE SURFACE RIDGE WILL KEEP THE AIR MASS DRY OVER THE AREA. THE MID LEVEL QUEBEC LOW WILL BACK INTO EASTERN ONTARIO WHILE DEEPENING TONIGHT. SHORTWAVES WILL SWEEP AROUND THE BASE OF THIS LOW AND INTO LOWER MICHIGAN AND THE LOWER GREAT LAKES. THE NORTHERN PLAINS RIDGE WILL EDGE INTO EASTERN DAKOTAS. SHORTWAVES WILL BE APPROACHING THE APEX OF THIS RIDGE. THE SURFACE RIDGE WILL EXPAND AND BLANKET THE UPPER GREAT LAKES...UPPER MISSISSIPPI RIVER VALLEY AND ONTARIO...AND MUCH OF HUDSON BAY. CLOUD COVER DUE TO THE WEAK SHORTWAVE AND A NORTHERLY FLOW WILL LIMIT HEATING TODAY. WILL GO WITH TEMPERATURES IN THE MID 70S WHICH WILL BE A LITTLE WARM THAN YESTERDAY. THE MID LEVEL LOW WILL BACK INTO LAKE HURON AS THE RIDGE PUSHES INTO WESTERN ONTARIO AND THE UPPER MISSISSIPPI RIVER VALLEY WEDNESDAY AND WEDNESDAY NIGHT. SHORTWAVES WILL CONTINUE TO PUSH INTO THE RIDGE BUT WILL REMAIN OVER THE DAKOTAS AND MANITOBA. THE SURFACE RIDGE WILL REMAIN OVER ONTARIO AND THE UPPER GREAT LAKES. MEANWHILE THE SURFACE LOW OVER SASKATCHEWAN WILL SHIFT INTO CENTRAL MANITOBA. FRONTOGENESIS WITH THIS LOW WILL PRODUCE A FRONT OVER THE DAKOTAS AND MANITOBA. THE MID LEVEL LOW WILL EDGE INTO WESTERN QUEBEC ON THURSDAY WHILE THE RIDGE CONTINUES OVER CENTRAL ONTARIO WHILE WEAKENING. A WEAK SHORTWAVE MOVING THROUGH THE RIDGE WILL SHIFT INTO THE WESTERN U.P. ANOTHER MID LEVEL WILL DEVELOP OVER NORTHERN MANITOBA. THE SURFACE LOW WILL MOVE TO JUST NORTHEAST OF LAKE WINNIPEG DRAGGING THE COLD FRONT INTO WESTERN MINNESOTA. WEAK SHORTWAVE ENERGY AND ISENTROPIC ASCENT AHEAD OF THE APPROACHING COLD FRONT WILL GENERATE A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS OVER THE FAR WESTERN U.P. LATE ON THURSDAY. THE MID LEVEL CLOSED LOW WILL REMAIN JUST EAST OF HUDSON BAY THURSDAY NIGHT. THE MID LEVEL LOW OVER MANITOBA WILL EDGE INTO WESTERN ONTARIO. THE RIDGE SEPARATING THESE WILL WEAKEN EVEN MORE AS IT SHIFT OVER THE FORECAST AREA. THE COLD FRONT AND ACCOMPANYING LOW WILL EDGE INTO THE UPPER MISSISSIPPI RIVER VALLEY. ISENTROPIC ASCENT AHEAD OF THE FRONT WILL LEAD TO A CHANCE OF SOME SHOWERS AND THUNDERSTORMS DEVELOPING OVER THE AREA. THE LOW OVER MANITOBA WILL MOVE INTO NORTHWEST ONTARIO ON FRIDAY. SHORTWAVES WRAPPING THROUGH THE BASE OF THIS LOW ALONG WITH THE COLD FRONT WHICH WILL MOVE INTO WESTERN LAKE SUPERIOR WILL CONTRIBUTE TO THE CHANCE OF SHOWERS AND THUNDERSTORMS CONTINUING ACROSS THE FORECAST AREA. THE COLD FRONT AND THE SHORTWAVE ENERGY WILL REACH KANJ BY SUNRISE SATURDAY MORNING. DRY AIR WILL MOVE OVER THE AREA BRINGING FAIR WEATHER TO THE AREA FOR WEEK END. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... ALTHOUGH THERE WL BE SOME MID CLDS ARND THIS MRNG AND SOME DIURNAL CU THIS AFTN...EXPECT VFR CONDITIONS THIS FCST PD WITH DRY HI PRES BLDG TOWARD LK SUP. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT HIGH PRESSURE OVER HUDSON BAY TO BUILD SOUTH OVER LAKE SUPERIOR ON WEDNESDAY AND THEN INTO THE LOWER GREAT LAKES ON THURSDAY. LINGERING FOG OVER LAKE SUPERIOR WILL DISSIPATE THIS MORNING AS DRY AIR ASSOCIATED WITH THE HIGH CONTINUES TO ADVECT OVER THE LAKE. AS THIS HIGH DRIFTS INTO THE MID ATLANTIC STATES ON FRIDAY...A LOW PRESSURE TROUGH WILL MOVE INTO THE UPPER GREAT LAKES. LOOK FOR THIS TROUGH TO DRIFT INTO THE CENTRAL GREAT LAKES ON SATURDAY IN ADVANCE OF HIGH PRESSURE BUILDING TOWARD THE NORTHERN PLAINS. OTHERWISE...WINDS WILL BE NO GREATER THAN 20 KNOTS THROUGH THE END OF THE WEEK. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...DLG AVIATION...KC MARINE...KC mi AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MARQUETTE MI 720 AM EDT TUE JUL 22 2008 UPDATED FOR 12Z TAF ISSUANCE .DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST PACKAGE ARE THE TEMPERATURES TODAY AND TONIGHT. WATER VAPOR AND RUC SHOWING A CLOSED LOW OVER QUEBEC WITH WEAK SHORTWAVE WRAPPING THROUGH ITS BASES. THESE ARE OVER EASTERN LAKE SUPERIOR AND NORTHERN ONTARIO. A LARGE RIDGE IS BUILDING OVER THE HIGH PLAINS AND EXTENDING NORTHEAST INTO THE CANADIAN PRAIRIE. ANOTHER LONGWAVE TROUGH DIGGING OVER THE PACIFIC NORTHWEST. SURFACE ANALYSIS DEPICTS A HIGH OVER HUDSON BAY AND ONTARIO. A LOW DEEPENING OVER THE SOUTHWEST SASKATCHEWAN. A STATIONARY FRONT STRETCHES FROM THE CENTRAL PLAINS ACROSS THE OHIO RIVER VALLEY TO NEW ENGLAND. THIS ESSENTIALLY CUTS OFF MOISTURE FROM THE GULF AND OCEAN. THE MID LEVEL RIDGE WILL SHIFT INTO THE NORTHERN PLAINS AND MANITOBA TODAY...WHILE THE LOW CONTINUES TO SPIN OVER QUEBEC AND EASTERN ONTARIO. THE LAKE SUPERIOR SHORTWAVE WILL SHIFT EAST...WHILE THE ONTARIO SHORTWAVE SWEEPS THROUGH WISCONSIN. THE SURFACE HIGH WILL CONTINUE OVER HUDSON BAY AND BLANKETING NORTHERN ONTARIO AND MUCH OF THE UPPER GREAT LAKES. DRY AIR ACCOMPANYING THE SURFACE RIDGE WILL KEEP THE AIR MASS DRY OVER THE AREA. THE MID LEVEL QUEBEC LOW WILL BACK INTO EASTERN ONTARIO WHILE DEEPENING TONIGHT. SHORTWAVES WILL SWEEP AROUND THE BASE OF THIS LOW AND INTO LOWER MICHIGAN AND THE LOWER GREAT LAKES. THE NORTHERN PLAINS RIDGE WILL EDGE INTO EASTERN DAKOTAS. SHORTWAVES WILL BE APPROACHING THE APEX OF THIS RIDGE. THE SURFACE RIDGE WILL EXPAND AND BLANKET THE UPPER GREAT LAKES...UPPER MISSISSIPPI RIVER VALLEY AND ONTARIO...AND MUCH OF HUDSON BAY. CLOUD COVER DUE TO THE WEAK SHORTWAVE AND A NORTHERLY FLOW WILL LIMIT HEATING TODAY. WILL GO WITH TEMPERATURES IN THE MID 70S WHICH WILL BE A LITTLE WARM THAN YESTERDAY. THE MID LEVEL LOW WILL BACK INTO LAKE HURON AS THE RIDGE PUSHES INTO WESTERN ONTARIO AND THE UPPER MISSISSIPPI RIVER VALLEY WEDNESDAY AND WEDNESDAY NIGHT. SHORTWAVES WILL CONTINUE TO PUSH INTO THE RIDGE BUT WILL REMAIN OVER THE DAKOTAS AND MANITOBA. THE SURFACE RIDGE WILL REMAIN OVER ONTARIO AND THE UPPER GREAT LAKES. MEANWHILE THE SURFACE LOW OVER SASKATCHEWAN WILL SHIFT INTO CENTRAL MANITOBA. FRONTOGENESIS WITH THIS LOW WILL PRODUCE A FRONT OVER THE DAKOTAS AND MANITOBA. THE MID LEVEL LOW WILL EDGE INTO WESTERN QUEBEC ON THURSDAY WHILE THE RIDGE CONTINUES OVER CENTRAL ONTARIO WHILE WEAKENING. A WEAK SHORTWAVE MOVING THROUGH THE RIDGE WILL SHIFT INTO THE WESTERN U.P. ANOTHER MID LEVEL WILL DEVELOP OVER NORTHERN MANITOBA. THE SURFACE LOW WILL MOVE TO JUST NORTHEAST OF LAKE WINNIPEG DRAGGING THE COLD FRONT INTO WESTERN MINNESOTA. WEAK SHORTWAVE ENERGY AND ISENTROPIC ASCENT AHEAD OF THE APPROACHING COLD FRONT WILL GENERATE A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS OVER THE FAR WESTERN U.P. LATE ON THURSDAY. THE MID LEVEL CLOSED LOW WILL REMAIN JUST EAST OF HUDSON BAY THURSDAY NIGHT. THE MID LEVEL LOW OVER MANITOBA WILL EDGE INTO WESTERN ONTARIO. THE RIDGE SEPARATING THESE WILL WEAKEN EVEN MORE AS IT SHIFT OVER THE FORECAST AREA. THE COLD FRONT AND ACCOMPANYING LOW WILL EDGE INTO THE UPPER MISSISSIPPI RIVER VALLEY. ISENTROPIC ASCENT AHEAD OF THE FRONT WILL LEAD TO A CHANCE OF SOME SHOWERS AND THUNDERSTORMS DEVELOPING OVER THE AREA. THE LOW OVER MANITOBA WILL MOVE INTO NORTHWEST ONTARIO ON FRIDAY. SHORTWAVES WRAPPING THROUGH THE BASE OF THIS LOW ALONG WITH THE COLD FRONT WHICH WILL MOVE INTO WESTERN LAKE SUPERIOR WILL CONTRIBUTE TO THE CHANCE OF SHOWERS AND THUNDERSTORMS CONTINUING ACROSS THE FORECAST AREA. THE COLD FRONT AND THE SHORTWAVE ENERGY WILL REACH KANJ BY SUNRISE SATURDAY MORNING. DRY AIR WILL MOVE OVER THE AREA BRINGING FAIR WEATHER TO THE AREA FOR WEEK END. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... ALTHOUGH THERE WL BE SOME MID CLDS ARND THIS MRNG AND SOME DIURNAL CU THIS AFTN...EXPECT VFR CONDITIONS THIS FCST PD WITH DRY HI PRES BLDG TOWARD LK SUP. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT HIGH PRESSURE OVER HUDSON BAY TO BUILD SOUTH OVER LAKE SUPERIOR ON WEDNESDAY AND THEN INTO THE LOWER GREAT LAKES ON THURSDAY. LINGERING FOG OVER LAKE SUPERIOR WILL DISSIPATE THIS MORNING AS DRY AIR ASSOCIATED WITH THE HIGH CONTINUES TO ADVECT OVER THE LAKE. AS THIS HIGH DRIFTS INTO THE MID ATLANTIC STATES ON FRIDAY...A LOW PRESSURE TROUGH WILL MOVE INTO THE UPPER GREAT LAKES. LOOK FOR THIS TROUGH TO DRIFT INTO THE CENTRAL GREAT LAKES ON SATURDAY IN ADVANCE OF HIGH PRESSURE BUILDING TOWARD THE NORTHERN PLAINS. OTHERWISE...WINDS WILL BE NO GREATER THAN 20 KNOTS THROUGH THE END OF THE WEEK. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...DLG AVIATION...KC MARINE...KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 345 AM EDT TUE JUL 22 2008 .DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST PACKAGE ARE THE TEMPERATURES TODAY AND TONIGHT. WATER VAPOR AND RUC SHOWING A CLOSED LOW OVER QUEBEC WITH WEAK SHORTWAVE WRAPPING THROUGH ITS BASES. THESE ARE OVER EASTERN LAKE SUPERIOR AND NORTHERN ONTARIO. A LARGE RIDGE IS BUILDING OVER THE HIGH PLAINS AND EXTENDING NORTHEAST INTO THE CANADIAN PRAIRIE. ANOTHER LONGWAVE TROUGH DIGGING OVER THE PACIFIC NORTHWEST. SURFACE ANALYSIS DEPICTS A HIGH OVER HUDSON BAY AND ONTARIO. A LOW DEEPENING OVER THE SOUTHWEST SASKATCHEWAN. A STATIONARY FRONT STRETCHES FROM THE CENTRAL PLAINS ACROSS THE OHIO RIVER VALLEY TO NEW ENGLAND. THIS ESSENTIALLY CUTS OFF MOISTURE FROM THE GULF AND OCEAN. THE MID LEVEL RIDGE WILL SHIFT INTO THE NORTHERN PLAINS AND MANITOBA TODAY...WHILE THE LOW CONTINUES TO SPIN OVER QUEBEC AND EASTERN ONTARIO. THE LAKE SUPERIOR SHORTWAVE WILL SHIFT EAST...WHILE THE ONTARIO SHORTWAVE SWEEPS THROUGH WISCONSIN. THE SURFACE HIGH WILL CONTINUE OVER HUDSON BAY AND BLANKETING NORTHERN ONTARIO AND MUCH OF THE UPPER GREAT LAKES. DRY AIR ACCOMPANYING THE SURFACE RIDGE WILL KEEP THE AIR MASS DRY OVER THE AREA. THE MID LEVEL QUEBEC LOW WILL BACK INTO EASTERN ONTARIO WHILE DEEPENING TONIGHT. SHORTWAVES WILL SWEEP AROUND THE BASE OF THIS LOW AND INTO LOWER MICHIGAN AND THE LOWER GREAT LAKES. THE NORTHERN PLAINS RIDGE WILL EDGE INTO EASTERN DAKOTAS. SHORTWAVES WILL BE APPROACHING THE APEX OF THIS RIDGE. THE SURFACE RIDGE WILL EXPAND AND BLANKET THE UPPER GREAT LAKES...UPPER MISSISSIPPI RIVER VALLEY AND ONTARIO...AND MUCH OF HUDSON BAY. CLOUD COVER DUE TO THE WEAK SHORTWAVE AND A NORTHERLY FLOW WILL LIMIT HEATING TODAY. WILL GO WITH TEMPERATURES IN THE MID 70S WHICH WILL BE A LITTLE WARM THAN YESTERDAY. THE MID LEVEL LOW WILL BACK INTO LAKE HURON AS THE RIDGE PUSHES INTO WESTERN ONTARIO AND THE UPPER MISSISSIPPI RIVER VALLEY WEDNESDAY AND WEDNESDAY NIGHT. SHORTWAVES WILL CONTINUE TO PUSH INTO THE RIDGE BUT WILL REMAIN OVER THE DAKOTAS AND MANITOBA. THE SURFACE RIDGE WILL REMAIN OVER ONTARIO AND THE UPPER GREAT LAKES. MEANWHILE THE SURFACE LOW OVER SASKATCHEWAN WILL SHIFT INTO CENTRAL MANITOBA. FRONTOGENESIS WITH THIS LOW WILL PRODUCE A FRONT OVER THE DAKOTAS AND MANITOBA. THE MID LEVEL LOW WILL EDGE INTO WESTERN QUEBEC ON THURSDAY WHILE THE RIDGE CONTINUES OVER CENTRAL ONTARIO WHILE WEAKENING. A WEAK SHORTWAVE MOVING THROUGH THE RIDGE WILL SHIFT INTO THE WESTERN U.P. ANOTHER MID LEVEL WILL DEVELOP OVER NORTHERN MANITOBA. THE SURFACE LOW WILL MOVE TO JUST NORTHEAST OF LAKE WINNIPEG DRAGGING THE COLD FRONT INTO WESTERN MINNESOTA. WEAK SHORTWAVE ENERGY AND ISENTROPIC ASCENT AHEAD OF THE APPROACHING COLD FRONT WILL GENERATE A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS OVER THE FAR WESTERN U.P. LATE ON THURSDAY. THE MID LEVEL CLOSED LOW WILL REMAIN JUST EAST OF HUDSON BAY THURSDAY NIGHT. THE MID LEVEL LOW OVER MANITOBA WILL EDGE INTO WESTERN ONTARIO. THE RIDGE SEPARATING THESE WILL WEAKEN EVEN MORE AS IT SHIFT OVER THE FORECAST AREA. THE COLD FRONT AND ACCOMPANYING LOW WILL EDGE INTO THE UPPER MISSISSIPPI RIVER VALLEY. ISENTROPIC ASCENT AHEAD OF THE FRONT WILL LEAD TO A CHANCE OF SOME SHOWERS AND THUNDERSTORMS DEVELOPING OVER THE AREA. THE LOW OVER MANITOBA WILL MOVE INTO NORTHWEST ONTARIO ON FRIDAY. SHORTWAVES WRAPPING THROUGH THE BASE OF THIS LOW ALONG WITH THE COLD FRONT WHICH WILL MOVE INTO WESTERN LAKE SUPERIOR WILL CONTRIBUTE TO THE CHANCE OF SHOWERS AND THUNDERSTORMS CONTINUING ACROSS THE FORECAST AREA. THE COLD FRONT AND THE SHORTWAVE ENERGY WILL REACH KANJ BY SUNRISE SATURDAY MORNING. DRY AIR WILL MOVE OVER THE AREA BRINGING FAIR WEATHER TO THE AREA FOR WEEK END. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... EXPECT THE COMBINATION OF SOME LLVL DRY ADVCTN AND MID CLD TO REDUCE THE CHCS FOR SGNFT RADIATION FOG TNGT...BUT SOME FOG/ST MAY FORM OVERNGT...ESPECIALLY AT SAW WITH MORE FVRBL UPSLOPE NLY WIND COMPONENT AND MORE RECENT RA. ANY FOG/ST WL BURN OFF BY MID MRNG... WITH VFR CONDITIONS PREDOMINATING TDAY AS DRY HI PRES BLDS TOWARD LK SUP. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT HIGH PRESSURE OVER HUDSON BAY TO BUILD SOUTH OVER LAKE SUPERIOR ON WEDNESDAY AND THEN INTO THE LOWER GREAT LAKES ON THURSDAY. LINGERING FOG OVER LAKE SUPERIOR WILL DISSIPATE THIS MORNING AS DRY AIR ASSOCIATED WITH THE HIGH CONTINUES TO ADVECT OVER THE LAKE. AS THIS HIGH DRIFTS INTO THE MID ATLANTIC STATES ON FRIDAY...A LOW PRESSURE TROUGH WILL MOVE INTO THE UPPER GREAT LAKES. LOOK FOR THIS TROUGH TO DRIFT INTO THE CENTRAL GREAT LAKES ON SATURDAY IN ADVANCE OF HIGH PRESSURE BUILDING TOWARD THE NORTHERN PLAINS. OTHERWISE...WINDS WILL BE NO GREATER THAN 20 KNOTS THROUGH THE END OF THE WEEK. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...DLG AVIATION...KC MARINE...KC mi AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MARQUETTE MI 120 PM EDT MON JUL 21 2008 UPDATED FOR 18Z TAF DISCUSSION .DISCUSSION (ISSUED AT 345 AM EDT)... WATER VAPOR IMAGERY AND RUC SHOWING LOW OVER NORTHERN ONTARIO...AND RIDGE OVER MUCH OF THE MID SECTION OF THE CONUS EXTENDING NORTH INTO CANADIAN PRAIRIE. SHORTWAVES ROTATING AROUND THE BASE OF THE ONTARIO LOW ARE SWEEPING THROUGH LAKE SUPERIOR...EASTERN U.P. AND NORTHERN WISCONSIN. SURFACE ANALYSIS DEPICTS A LOW OVER NORTHERN LAKE HURON WITH A COLD FRONT DRAPED SOUTHWEST INTO NORTHERN ILLINOIS...THEN WEST INTO CENTRAL PLAINS. A LARGE SURFACE HIGH IS OVER HUDSON BAY BLANKETING SOUTH CENTRAL CANADA. DEEP MOISTURE IS MAINLY OVER CENTRAL ONTARIO. THE LOW OVER CENTRAL ONTARIO WILL SHIFT INTO EAST CENTRAL ONTARIO TODAY. SHORTWAVES WILL SWEEP THROUGH THE BASE OF THE LOW. AS SUCH THE EASTERN U.P. LOW WILL SHIFT INTO EAST CENTRAL ONTARIO...WHILE THE LOW OVER NORTHERN WISCONSIN SWEEPS TO THE SOUTH OF THE FORECAST AREA. ANOTHER SHORTWAVE WILL DEVELOPING OVER WESTERN ONTARIO AND PRODUCING SCATTERED SHOWERS AND THUNDERSTORMS WILL SHIFT INTO MINNESOTA ARROWHEAD THIS AFTERNOON. COOL AIR MOVING OVER THE AREA BETWEEN 850MB AND 700MB WILL FURTHER DESTABILIZE THE AIR MASS AIDING IN CONVECTION THIS AFTERNOON. MUCAPE VALUES UP TO 1000J/KG WILL SPREAD INTO THE WESTERN U.P. SURFACE HEATING TODAY SHOULD CAUSE SOME LAKE BREEZES FRONTS TO SET UP WHICH HAS THE POTENTIAL TO TRIGGER A FEW SHOWERS AND THUNDERSTORMS. THE LIMITING FACTOR WILL BE AVAILABLE MOISTURE. PW SUGGESTING DRIER AIR WILL SETTLE INTO THE AREA FROM ONTARIO BY LATE AFTERNOON. THUS PLAN TO KEEP A LITTLE HIGHER POPS MAINLY OVER THE WEST...EXCEPT FOR THE KEWEENAW PENINSULA WHERE DRIER AIR WILL SETTLE IN FIRST. TEMPERATURES SHOULD CLIMB INTO THE LOW 70S TODAY. THE MID LEVEL LOW WILL SETTLE SOUTH INTO NORTHERN GEORGIAN BAY. SHORTWAVE ENERGY WILL SWEEP THROUGH THE FORECAST AREA TONIGHT. FORECAST SOUNDING SHOWING DRIER AIR BELOW 800MB ADVECTING INTO THE AREA. A SURFACE RIDGE WILL PUSH INTO THE FORECAST AREA. MUCAPE VALUE WILL FALL OFF TO ZERO. THUS LOOKING FOR CONDITIONS TO CLEAR BY MIDNIGHT. GFS/ECMWF SHOWING THE MID LEVEL LOW WILL BACK TO JUST SOUTH OF JAMES BAY ON TUESDAY AND TO SOUTHEAST ONTARIO ON WEDNESDAY. THE SHORTWAVE ROTATING AROUND THE BASE OF THE LOW WILL SWEEP THROUGH THE AREA. THE SURFACE RIDGE AND DRY AIR WILL REMAIN OVER THE AREA. THUS WILL KEEP CONDITIONS DRY THROUGH WEDNESDAY. THE MID LEVEL LOW WILL SHIFT NORTHEAST TO JUST SOUTHEAST OF JAMES BAY ON THURSDAY. A SHORTWAVE WILL PUSH THROUGH THE AREA. HOWEVER...THE SURFACE RIDGE WILL KEEP THE AIR MASS DRY. THE SURFACE RIDGE WILL START TO EDGE INTO QUEBEC...ALLOWING A COLD FRONT TO MOVE INTO MINNESOTA. ISENTROPIC ASCENT AHEAD OF THE FRONT AND LOW LEVEL MOISTURE ACCOMPANYING THE FRONT WILL GENERATE A CHANCE OF SHOWERS OVER THE FAR WEST BY LATE THURSDAY. THE SURFACE RIDGE WILL TRACK EASTWARD ON THURSDAY AND FRIDAY. THUS LOOKING FOR A CHANCE OF SHOWERS AND THUNDERSTORMS THURSDAY NIGHT AND EARLY FRIDAY. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... FOG HAS NOW LIFTED AT BOTH SITES. AT SAW THERE REMAINS A SMALL POSSIBILITY OF AFTERNOON SHOWERS OR THUNDERSTORMS...BUT WITH DRY AIR MOVING IN...ANY DEVELOPMENT MAY BE FARTHER INLAND. ANOTHER ROUND OF FOG MAY BE POSSIBLE AT SAW TONIGHT. HINTED AT THIS WITH 3SM BETWEEN 06Z AND 10Z...BEFORE WIND...STILL OUT OF THE NORTH...PICKS UP. CONTINUE TO GO WITH A DRIER SOLUTION WHEN COMPARED TO THE MODEL GUIDANCE. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT LOW PRESSURE NEAR THE STRAITS OF MACKINAC THIS MORNING TO DRIFT SLOWLY ACROSS SOUTHEAST ONTARIO THROUGH TONIGHT WHILE HIGH PRESSURE OVER HUDSON BAY BUILDS TOWARD WESTERN LAKE SUPERIOR. THIS HIGH WILL MOVE OVER LAKE SUPERIOR ON WEDNESDAY AND THEN INTO THE LOWER GREAT LAKES ON THURSDAY AS IT WEAKENS. ONCE THE RIDGE SHIFTS INTO THE OHIO VALLEY ON FRIDAY...A LOW PRESSURE TROUGH WILL MOVE INTO THE UPPER GREAT LAKES. EXPECT WINDS NO HIGHER THAN 20 KNOTS THIS FORECAST PERIOD WITH RELATIVELY WEAK PRESSURE GRADIENT. LATEST SATELLITE IMAGERY AND SURFACE OBSERVATIONS SUGGEST FOG IS STILL PRESENT OVER MUCH OF LAKE SUPERIOR WITH SURFACE DEWPOINTS QUITE A BIT HIGHER THAN LAKE WATER TEMPERATURE. LATEST MODEL GUIDANCE SHOWS DRIER AIR WILL FINALLY ARRIVE FROM THE NORTHEAST TODAY SOUTH OF BUILDING HIGH PRESSURE IN ONTARIO...SO WILL ALLOW GOING DENSE FOG ADVISORIES TO EXPIRE AS SCHEDULED AT 16Z. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ DISCUSSION...DLG AVIATION...KF MARINE...KC mi AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MARQUETTE MI 720 AM EDT MON JUL 21 2008 UPDATED FOR 12Z TAF DISCUSSION .DISCUSSION... WATER VAPOR IMAGERY AND RUC SHOWING LOW OVER NORTHERN ONTARIO...AND RIDGE OVER MUCH OF THE MID SECTION OF THE CONUS EXTENDING NORTH INTO CANADIAN PRAIRIE. SHORTWAVES ROTATING AROUND THE BASE OF THE ONTARIO LOW ARE SWEEPING THROUGH LAKE SUPERIOR...EASTERN U.P. AND NORTHERN WISCONSIN. SURFACE ANALYSIS DEPICTS A LOW OVER NORTHERN LAKE HURON WITH A COLD FRONT DRAPED SOUTHWEST INTO NORTHERN ILLINOIS...THEN WEST INTO CENTRAL PLAINS. A LARGE SURFACE HIGH IS OVER HUDSON BAY BLANKETING SOUTH CENTRAL CANADA. DEEP MOISTURE IS MAINLY OVER CENTRAL ONTARIO. THE LOW OVER CENTRAL ONTARIO WILL SHIFT INTO EAST CENTRAL ONTARIO TODAY. SHORTWAVES WILL SWEEP THROUGH THE BASE OF THE LOW. AS SUCH THE EASTERN U.P. LOW WILL SHIFT INTO EAST CENTRAL ONTARIO...WHILE THE LOW OVER NORTHERN WISCONSIN SWEEPS TO THE SOUTH OF THE FORECAST AREA. ANOTHER SHORTWAVE WILL DEVELOPING OVER WESTERN ONTARIO AND PRODUCING SCATTERED SHOWERS AND THUNDERSTORMS WILL SHIFT INTO MINNESOTA ARROWHEAD THIS AFTERNOON. COOL AIR MOVING OVER THE AREA BETWEEN 850MB AND 700MB WILL FURTHER DESTABILIZE THE AIR MASS AIDING IN CONVECTION THIS AFTERNOON. MUCAPE VALUES UP TO 1000J/KG WILL SPREAD INTO THE WESTERN U.P. SURFACE HEATING TODAY SHOULD CAUSE SOME LAKE BREEZES FRONTS TO SET UP WHICH HAS THE POTENTIAL TO TRIGGER A FEW SHOWERS AND THUNDERSTORMS. THE LIMITING FACTOR WILL BE AVAILABLE MOISTURE. PW SUGGESTING DRIER AIR WILL SETTLE INTO THE AREA FROM ONTARIO BY LATE AFTERNOON. THUS PLAN TO KEEP A LITTLE HIGHER POPS MAINLY OVER THE WEST...EXCEPT FOR THE KEWEENAW PENINSULA WHERE DRIER AIR WILL SETTLE IN FIRST. TEMPERATURES SHOULD CLIMB INTO THE LOW 70S TODAY. THE MID LEVEL LOW WILL SETTLE SOUTH INTO NORTHERN GEORGIAN BAY. SHORTWAVE ENERGY WILL SWEEP THROUGH THE FORECAST AREA TONIGHT. FORECAST SOUNDING SHOWING DRIER AIR BELOW 800MB ADVECTING INTO THE AREA. A SURFACE RIDGE WILL PUSH INTO THE FORECAST AREA. MUCAPE VALUE WILL FALL OFF TO ZERO. THUS LOOKING FOR CONDITIONS TO CLEAR BY MIDNIGHT. GFS/ECMWF SHOWING THE MID LEVEL LOW WILL BACK TO JUST SOUTH OF JAMES BAY ON TUESDAY AND TO SOUTHEAST ONTARIO ON WEDNESDAY. THE SHORTWAVE ROTATING AROUND THE BASE OF THE LOW WILL SWEEP THROUGH THE AREA. THE SURFACE RIDGE AND DRY AIR WILL REMAIN OVER THE AREA. THUS WILL KEEP CONDITIONS DRY THROUGH WEDNESDAY. THE MID LEVEL LOW WILL SHIFT NORTHEAST TO JUST SOUTHEAST OF JAMES BAY ON THURSDAY. A SHORTWAVE WILL PUSH THROUGH THE AREA. HOWEVER...THE SURFACE RIDGE WILL KEEP THE AIR MASS DRY. THE SURFACE RIDGE WILL START TO EDGE INTO QUEBEC...ALLOWING A COLD FRONT TO MOVE INTO MINNESOTA. ISENTROPIC ASCENT AHEAD OF THE FRONT AND LOW LEVEL MOISTURE ACCOMPANYING THE FRONT WILL GENERATE A CHANCE OF SHOWERS OVER THE FAR WEST BY LATE THURSDAY. THE SURFACE RIDGE WILL TRACK EASTWARD ON THURSDAY AND FRIDAY. THUS LOOKING FOR A CHANCE OF SHOWERS AND THUNDERSTORMS THURSDAY NIGHT AND EARLY FRIDAY. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... WITH ONSET OF DIURNAL HTG AND ARRIVAL OF DRIER AIR FM THE N THAT WAS DEPICTED ON THE 00Z YPL RAOB AND SUPPORTED BY SOME CLEARING OVER NRN LK SUP...EXPECT IFR FOG/ST NOW TO GRDLY GIVE WAY TO VFR CONDITIONS THIS AFTN. THE PROCESS WL BE SLOWER AT SAW WITH UPSLOPE NNE FLOW AND MORE WDSPRD FOG/ST THAN THE PTCHY NATURE OF THIS ACRS THE KEWEENAW. ALTHOUGH SOME UPR DISTURBANCES WL BE SWINGING SEWD IN THE NW FLOW ALF THIS AFTN/TNGT...THINK STABILIZING INFLUENCE OF LK SUP/ARRIVAL OF DRIER AIR WL KEEP DIURNAL SHRA CHCS SO LO AT CMX AS NOT TO INCLUDE IN FCST. SINCE SAW IS FARTHER S...DIURNAL HTG MAY BE ENUF TO KICK OFF A SHRA THERE BEFORE TOO MUCH DRY AIR ARRIVES. GIVEN THE DRYING OBSVD UPSTREAM ACRS ONTARIO/NRN LK SUP...PREFER THE SOMEWHAT DRIER NAM FCST FOR TNGT WITH JUST SOME SCT-BKN SC/AC AND VFR CONDITIONS. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT LOW PRESSURE NEAR THE STRAITS OF MACKINAC THIS MORNING TO DRIFT SLOWLY ACROSS SOUTHEAST ONTARIO THROUGH TONIGHT WHILE HIGH PRESSURE OVER HUDSON BAY BUILDS TOWARD WESTERN LAKE SUPERIOR. THIS HIGH WILL MOVE OVER LAKE SUPERIOR ON WEDNESDAY AND THEN INTO THE LOWER GREAT LAKES ON THURSDAY AS IT WEAKENS. ONCE THE RIDGE SHIFTS INTO THE OHIO VALLEY ON FRIDAY...A LOW PRESSURE TROUGH WILL MOVE INTO THE UPPER GREAT LAKES. EXPECT WINDS NO HIGHER THAN 20 KNOTS THIS FORECAST PERIOD WITH RELATIVELY WEAK PRESSURE GRADIENT. LATEST SATELLITE IMAGERY AND SURFACE OBSERVATIONS SUGGEST FOG IS STILL PRESENT OVER MUCH OF LAKE SUPERIOR WITH SURFACE DEWPOINTS QUITE A BIT HIGHER THAN LAKE WATER TEMPERATURE. LATEST MODEL GUIDANCE SHOWS DRIER AIR WILL FINALLY ARRIVE FROM THE NORTHEAST TODAY SOUTH OF BUILDING HIGH PRESSURE IN ONTARIO...SO WILL ALLOW GOING DENSE FOG ADVISORIES TO EXPIRE AS SCHEDULED AT 16Z. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. DENSE FOG ADVISORY UNTIL 12 PM EDT /11 AM CDT/ TODAY FOR LSZ162-240>248-263>266. LAKE MICHIGAN...NONE. && $$ DISCUSSION...DLG AVIATION...KC MARINE...KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 345 AM EDT MON JUL 21 2008 .DISCUSSION... WATER VAPOR IMAGERY AND RUC SHOWING LOW OVER NORTHERN ONTARIO...AND RIDGE OVER MUCH OF THE MID SECTION OF THE CONUS EXTENDING NORTH INTO CANADIAN PRAIRIE. SHORTWAVES ROTATING AROUND THE BASE OF THE ONTARIO LOW ARE SWEEPING THROUGH LAKE SUPERIOR...EASTERN U.P. AND NORTHERN WISCONSIN. SURFACE ANALYSIS DEPICTS A LOW OVER NORTHERN LAKE HURON WITH A COLD FRONT DRAPED SOUTHWEST INTO NORTHERN ILLINOIS...THEN WEST INTO CENTRAL PLAINS. A LARGE SURFACE HIGH IS OVER HUDSON BAY BLANKETING SOUTH CENTRAL CANADA. DEEP MOISTURE IS MAINLY OVER CENTRAL ONTARIO. THE LOW OVER CENTRAL ONTARIO WILL SHIFT INTO EAST CENTRAL ONTARIO TODAY. SHORTWAVES WILL SWEEP THROUGH THE BASE OF THE LOW. AS SUCH THE EASTERN U.P. LOW WILL SHIFT INTO EAST CENTRAL ONTARIO...WHILE THE LOW OVER NORTHERN WISCONSIN SWEEPS TO THE SOUTH OF THE FORECAST AREA. ANOTHER SHORTWAVE WILL DEVELOPING OVER WESTERN ONTARIO AND PRODUCING SCATTERED SHOWERS AND THUNDERSTORMS WILL SHIFT INTO MINNESOTA ARROWHEAD THIS AFTERNOON. COOL AIR MOVING OVER THE AREA BETWEEN 850MB AND 700MB WILL FURTHER DESTABILIZE THE AIR MASS AIDING IN CONVECTION THIS AFTERNOON. MUCAPE VALUES UP TO 1000J/KG WILL SPREAD INTO THE WESTERN U.P. SURFACE HEATING TODAY SHOULD CAUSE SOME LAKE BREEZES FRONTS TO SET UP WHICH HAS THE POTENTIAL TO TRIGGER A FEW SHOWERS AND THUNDERSTORMS. THE LIMITING FACTOR WILL BE AVAILABLE MOISTURE. PW SUGGESTING DRIER AIR WILL SETTLE INTO THE AREA FROM ONTARIO BY LATE AFTERNOON. THUS PLAN TO KEEP A LITTLE HIGHER POPS MAINLY OVER THE WEST...EXCEPT FOR THE KEWEENAW PENINSULA WHERE DRIER AIR WILL SETTLE IN FIRST. TEMPERATURES SHOULD CLIMB INTO THE LOW 70S TODAY. THE MID LEVEL LOW WILL SETTLE SOUTH INTO NORTHERN GEORGIAN BAY. SHORTWAVE ENERGY WILL SWEEP THROUGH THE FORECAST AREA TONIGHT. FORECAST SOUNDING SHOWING DRIER AIR BELOW 800MB ADVECTING INTO THE AREA. A SURFACE RIDGE WILL PUSH INTO THE FORECAST AREA. MUCAPE VALUE WILL FALL OFF TO ZERO. THUS LOOKING FOR CONDITIONS TO CLEAR BY MIDNIGHT. GFS/ECMWF SHOWING THE MID LEVEL LOW WILL BACK TO JUST SOUTH OF JAMES BAY ON TUESDAY AND TO SOUTHEAST ONTARIO ON WEDNESDAY. THE SHORTWAVE ROTATING AROUND THE BASE OF THE LOW WILL SWEEP THROUGH THE AREA. THE SURFACE RIDGE AND DRY AIR WILL REMAIN OVER THE AREA. THUS WILL KEEP CONDITIONS DRY THROUGH WEDNESDAY. THE MID LEVEL LOW WILL SHIFT NORTHEAST TO JUST SOUTHEAST OF JAMES BAY ON THURSDAY. A SHORTWAVE WILL PUSH THROUGH THE AREA. HOWEVER...THE SURFACE RIDGE WILL KEEP THE AIR MASS DRY. THE SURFACE RIDGE WILL START TO EDGE INTO QUEBEC...ALLOWING A COLD FRONT TO MOVE INTO MINNESOTA. ISENTROPIC ASCENT AHEAD OF THE FRONT AND LOW LEVEL MOISTURE ACCOMPANYING THE FRONT WILL GENERATE A CHANCE OF SHOWERS OVER THE FAR WEST BY LATE THURSDAY. THE SURFACE RIDGE WILL TRACK EASTWARD ON THURSDAY AND FRIDAY. THUS LOOKING FOR A CHANCE OF SHOWERS AND THUNDERSTORMS THURSDAY NIGHT AND EARLY FRIDAY. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... FORECAST WILL BE TRICKY DUE TO POSSIBILITY OF STRATUS/FOG FORMING OVERNIGHT. SCT MID LEVEL CLOUDS COVER MUCH OF UPPER MI AT PRESENT. NORTHERLY WINDS DEVELOPING ON THE BACKSIDE OF A SFC TROF PASSAGE COULD ADVECT FOG/STRATUS IN FROM LAKE SUPERIOR OVERNIGHT. KEPT WITH IDEA OF PREVIOUS FCST GOING AS LOW AS IFR ON VSBY AND LIFR ON CIG. DAYTIME HEATING ALONG WITH DRIER AIR COMING OFF ONTARIO SHOULD HELP BRING VSBYS AND CIGS UP FAIRLY RAPIDLY ON MON...ESPECIALLY AT CMX WHERE THE EXPECTED NE WIND WILL BE A DOWNSLOPE WIND. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT LOW PRESSURE NEAR THE STRAITS OF MACKINAC THIS MORNING TO DRIFT SLOWLY ACROSS SOUTHEAST ONTARIO THROUGH TONIGHT WHILE HIGH PRESSURE OVER HUDSON BAY BUILDS TOWARD WESTERN LAKE SUPERIOR. THIS HIGH WILL MOVE OVER LAKE SUPERIOR ON WEDNESDAY AND THEN INTO THE LOWER GREAT LAKES ON THURSDAY AS IT WEAKENS. ONCE THE RIDGE SHIFTS INTO THE OHIO VALLEY ON FRIDAY...A LOW PRESSURE TROUGH WILL MOVE INTO THE UPPER GREAT LAKES. EXPECT WINDS NO HIGHER THAN 20 KNOTS THIS FORECAST PERIOD WITH RELATIVELY WEAK PRESSURE GRADIENT. LATEST SATELLITE IMAGERY AND SURFACE OBSERVATIONS SUGGEST FOG IS STILL PRESENT OVER MUCH OF LAKE SUPERIOR WITH SURFACE DEWPOINTS QUITE A BIT HIGHER THAN LAKE WATER TEMPERATURE. LATEST MODEL GUIDANCE SHOWS DRIER AIR WILL FINALLY ARRIVE FROM THE NORTHEAST TODAY SOUTH OF BUILDING HIGH PRESSURE IN ONTARIO...SO WILL ALLOW GOING DENSE FOG ADVISORIES TO EXPIRE AS SCHEDULED AT 16Z. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. DENSE FOG ADVISORY UNTIL 12 PM EDT /11 AM CDT/ TODAY FOR LSZ162-240>248-263>266. LAKE MICHIGAN...NONE. && $$ DISCUSSION...DLG AVIATION...VOSS MARINE...KC mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 120 AM EDT MON JUL 21 2008 UPDATED FOR 00Z AVIATION DISCUSSION .SYNOPSIS... 19Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED WEAK RIDGING OVER MT INTO SOUTHERN ALBERTA...AN UPPER TROUGH OVER NW ONTARIO/NRN MN AND A VERY WEAK RIDGE OVER UPPER MI. BETWEEN THE UPPER TROUGH AND THE VERY WEAK RIDGE...A SHRTWV IS MOVING INTO THE WRN U.P.. CLOUDS AHEAD OF THE SHRTWV HAVE BEEN VERY TOUGH TO CLEAR OUT...AND TAMDAR SOUNDINGS EXPLAIN WHY WITH CLOUD DEPTHS AROUND 2500 FT. ONLY AREA THAT WAS ABLE TO HAVE THE MOST SUN WAS OVER THE EAST CENTRAL U.P....LIKELY DUE TO THE LACK OF RAIN THERE LAST NIGHT TO CAUSE SATURATED LOW LEVELS. THIS AREA THAT HAS HAD SUN IS NOW FILLING IN WITH SHOWERS AND A FEW THUNDERSTORMS...AS LAKE BREEZES CONVERGE INTO AN AIRMASS THAT HAS MLCAPES AROUND 1000 J/KG. OTHER STORMS ARE FIRING ACROSS NORTHERN MN...WHICH ARE ASSOCIATED WITH AN UPPER LOW THAT HAS COLD MID-LEVEL TEMPS. THESE STORMS ARE ALSO GETTING A LITTLE HELP FROM RIGHT ENTRANCE REGION FORCING ASSOCIATED WITH A 90KT JET STREAK MOVING THROUGH CENTRAL MN. RELATIVELY HUMID CONDITIONS EXIST OVER THE NORTHERN GREAT LAKES...WITH DEWPOINTS IN THE LOW 60S F. GIVEN THAT THESE ARE AT LEAST 15F HIGHER THAN THE LAKE SUPERIOR TEMPS...SOME FOG CONTINUES ON LAKE SUPERIOR. SATELLITE ALSO DEPICTS SOME ACROSS NORTHERN LAKE MI. HOWEVER...SATELLITE IMAGES AND SOME RECENT SHIP OBS SUGGEST THE FOG IS NOT AS WIDESPREAD...AND PERHAPS NOT AS DENSE AS WELL. MID CLOUDS ACROSS LAKE SUPERIOR ARE PREVENTING A FULL GOOD ANALYSIS OF THE FOG...THOUGH. && .SHORT TERM (TONIGHT AND MONDAY)... SCATTERED SHOWERS AND THUNDERSTORMS SHOULD CONTINUE TO FIRE DURING THE REST OF THE AFTERNOON AND EVENING OVER THE CENTRAL U.P. AS THE SHRTWV OVER WESTERN UPPER MI PRESSES EAST. PCPN WILL ALSO GET HELP FROM THE UPPER JET CORE IN CENTRAL MN MOVING DOWN INTO NRN WI TO APPLY SOME UPPER LEVEL DIVERGENCE. MAY HAVE TO WATCH FOR AN ISOLATED SEVERE THUNDERSTORM...BUT RIGHT NOW THE STORMS APPEAR TO BE JUST BRIEF HEAVY RAIN PRODUCERS. UPPER LOW OVER NRN MN/FAR WRN ONTARIO IS PROGGED TO SHIFT ACROSS LAKE SUPERIOR TONIGHT...LIKELY BRINGING THE SHOWERS AND THUNDERSTORMS OVER NRN MN ACROSS. HOWEVER...SINCE THESE ARE SURFACE BASED...AM NOT EXPECTING ALL OF THEM TO MOVE INTO THE CWA. THEREFORE QPF AMOUNTS AND POPS REMAIN LOW ACROSS THE WESTERN U.P.. THE UPPER LOW SHOULD MOVE QUICK ENOUGH TO THE EAST TO ALLOW AT LEAST THE BORDER COUNTIES TO DRY OUT. IN THE NORTHERN U.P....THE FORECAST COMPLETELY DEPENDS ON WHAT HAPPENS WITH THE FOG/STRATUS ON LAKE SUPERIOR. GENERAL CONSENSUS FROM THE REGIONAL CANADIAN...NAM AND GFS IS TO SWING LOW CLOUDS OVER NORTHERN LAKE SUPERIOR SOUTHWARD INTO THE NORTHERN U.P. IN THE WAKE OF THE UPPER LOW. HAVE MAINTAINED 20 POPS FOR ANY SHOWERS OR DRIZZLE WITH THE LOW CLOUDS. OUR LOCAL WRF-ARW RUN IS SIMILAR BUT QUICKER IN DRIVING THE LOW CLOUDS SOUTHWARD. HAVE WENT AGAINST THIS AS THE MODEL IS MUCH DEEPER WITH A SURFACE LOW IT GENERATES FROM THE UPPER LOW. KEPT IN SOME PATCHY/AREAS OF FOG TO ACCOUNT FOR THIS EVENINGS RAIN AND WITH THE LOW CLOUDS MOVING SOUTH. LOW TEMPS LOOKED REASONABLE AND ONLY SLIGHT ADJUSTMENTS WERE NECESSARY. IN THE WAKE OF TONIGHTS UPPER LOW...AREA SHOULD BE UNDER AN UPPER TROUGH FOR MONDAY...PERHAPS AMPLIFYING A BIT AS A SHRTWV OVER NW ONTARIO AT 12Z DROPS SOUTH. THIS MEANS THE AREA WILL BE UNDER COOL AIR ALOFT...FAVORABLE FOR THE DEVELOPMENT OF AFTERNOON CONVECTION. PROBLEM AGAIN...THOUGH...IS THE LOW CLOUDS. THE REGIONAL CANADIAN SUGGESTS THE ENTIRE CWA BEING ENCOMPASSED BY THEM...WHICH IS PROBABLY A BIT TOO MUCH. THE NAM AND GFS ARE NOT NEARLY AS WIDESPREAD...MAINTAINING CLOUDS FOR A LITTLE WHILE OVER THE NORTHERN U.P....THEN CLEARING OUT IN THE AFTERNOON AS DRIER AIR WORKS IN FROM ONTARIO AND DAYTIME HEATING MIXES. PREFER THIS SCENARIO MORE. HAVE KEPT IN SOME 20 POPS IN THE MORNING FOR ANY SHOWERS/DRIZZLE ASSOCIATED WITH THE LOW CLOUDS. THEN IN THE AFTERNOON...RAISED POPS TO 40 FOR INLAND LOCATIONS AS SOME MINOR LAKE BREEZE COMES OFF LAKE MICHIGAN TO CONVERGE WITH THE GENERAL NE FLOW. WANTED TO GO HIGHER WITH POPS...SINCE THE GFS AND REGIONAL CANADIAN ALL SHOW THUNDERSTORMS FIRING...BUT THE 12Z NAM DOES NOT SHOW MUCH QPF AT ALL. EXPANDED TSTM CHANCE AREA AS WELL TO MATCH WHERE THE GFS LIFTED INDICES ARE LESS THAN ZERO. HIGH TEMPS ON MONDAY MAY BE SIMILAR TO THOSE TODAY SINCE THERE SHOULD BE QUITE A BIT OF CLOUDS AROUND IN THE MORNING. THEREFORE COOLED HIGHS A LITTLE...ESPECIALLY ALONG LAKE SUPERIOR WITH PERSISTENT NORTHERLY FLOW. && .LONG TERM (MON NIGHT THROUGH NEXT SUN)... NAM SHOWING A 500 MB TROUGH OVER NEW ENGLAND 00Z TUE WITH A SHORTWAVE ON THE BACKSIDE OF THE TROUGH MOVING THROUGH THE WESTERN CWA MON NIGHT. UPPER LEVEL RIDGING TO THE WEST STARTS TO SLOWLY MOVE INTO THE AREA BY LATE WED. GFS IS SIMILAR AND HAS SOME 850-500 MB Q-VECTOR CONVERGENCE FOR MON NIGHT WITH THAT SHORTWAVE AND A BIT OF MOISTURE IN THE MID LEVELS AS WELL AND THIS SHOULD HELP KICK OFF SOME SHOWERS ACROSS THE WESTERN HALF OF THE U.P. WITH THE EAST REMAINING DRY WITH MOISTURE AND DYNAMICS LACKING THERE. SINCE THERE IS LACK OF DIURNAL HEATING AS WELL THEN...WILL GO LOW CHANCE POPS FOR MON NIGHT ACROSS THE WEST HALF. FOR TUE...MOISTURE IS LACKING AND WILL KEEP DRY WITH BETTER MOISTURE AND DYNAMICS REMAINING TO THE SOUTH. OVERALL...DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST FOR TEMPERATURES OR WEATHER. IN THE EXTENDED...GFS...CANADIAN AND ECMWF SHOW A SHORTWAVE RIDGE INTO THE AREA 00Z THU WITH TROUGHING TO THE EAST AND ALSO ACROSS THE NORTHERN PLAINS THEN. THE TROUGHING IN THE NORTHERN PLAINS MOVES INTO THE UPPER GREAT LAKES LATE THU INTO FRI WITH THE TROUGH AXIS EAST OF HERE 00Z SUN. WILL GO MORE TOWARDS THE 00Z ECMWF AS IT HAS SOME CONTINUITY ON ITS SIDE. WILL KEEP POPS ACROSS THE EASTERN CWA FOR FRI WITH COLD FRONT AND LAKE BREEZES KICKING SOME CHANCE POPS OFF AND THEN GO DRY FOR THE WEEKEND. TEMPERATURES WILL CONTINUE TO BE NEAR NORMAL AND DID NOT MAKE TOO MANY CHANGES EXCEPT TO REMOVE POPS FOR FRI NIGHT. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... FORECAST WILL BE TRICKY DUE TO POSSIBILITY OF STRATUS/FOG FORMING OVERNIGHT. SCT MID LEVEL CLOUDS COVER MUCH OF UPPER MI AT PRESENT. NORTHERLY WINDS DEVELOPING ON THE BACKSIDE OF A SFC TROF PASSAGE COULD ADVECT FOG/STRATUS IN FROM LAKE SUPERIOR OVERNIGHT. KEPT WITH IDEA OF PREVIOUS FCST GOING AS LOW AS IFR ON VSBY AND LIFR ON CIG. DAYTIME HEATING ALONG WITH DRIER AIR COMING OFF ONTARIO SHOULD HELP BRING VSBYS AND CIGS UP FAIRLY RAPIDLY ON MON...ESPECIALLY AT CMX WHERE THE EXPECTED NE WIND WILL BE A DOWNSLOPE WIND. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... FOG REMAINS THE MOST PROBLEMATIC ISSUE WITH THE FORECAST...WITH AN OVERALL WEAK PRESSURE GRADIENT EXPECTED ACROSS LAKE SUPERIOR THROUGH FRIDAY TO MAINTAIN WIND SPEEDS AT 20 KT OR LESS. ALTHOUGH IT APPEARS FOG MAY HAVE DISSIPATED SOME ACROSS LAKE SUPERIOR...ENOUGH TO WARRANT DROPPING THE FOG COVERAGE FROM WIDESPREAD TO AREAS...STILL KEPT THE DENSE FOG ADVISORIES OUT WITH HIGH MOISTURE AROUND THE AREA CROSSING THE COOLER LAKE. IN FACT...SOME SHOWERS ARE EXPECTED TO CROSS LAKE SUPERIOR TONIGHT THAT COULD REDEVELOP FOG. FOG WILL DISSIPATE NE TO SW ON MONDAY AS DRIER AIR OVER NE ONTARIO MOVES DOWN ACROSS THE LAKE. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR... DENSE FOG ADVISORY UNTIL 12 PM EDT /11 AM CDT/ MONDAY FOR LSZ162- 240>248-263>266. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/SHORT TERM...AJ LONG TERM...GJM AVIATION...VOSS MARINE...AJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 1127 PM CDT TUE JUL 22 2008 ...UPDATE TO AVIATION... .UPDATE... SCATTERED CONVECTION WILL CONTINUE TO BE POSSIBLE TONIGHT AS A MODEST LOW LEVEL S-SW FLOW CONTINUES TO PRODUCE SOME MODEST LIFT ALONG AN ELEVATED NW-SE FRONTAL BOUNDARY FROM NW MO INTO THE MO OZARKS. CAPES DEPICTED BY THE RUC STILL PRETTY STOUT OVER KS...WITH MLCAPES 2000+ J/KG. THIS WEAKENS INTO THE MO OZARKS... WITH MLCAPES OF 500-1500 J/KG...BUT MUCAPES STILL 1500-2000 J/KG. STILL HAVE ONE GOOD PERSISTENT UPDRAFT OVER EAST CENTRAL KS...AND A WEAKER CLUSTER OVER WEST CENTRAL MO. BELIEVE WE WILL SEE THIS ELEVATED CONVECTION CONTINUE FOR AWHILE INTO THE OVERNIGHT HOURS. MAY BE A SIMILAR STORY FOR THE COMING DAYS...WITH THE NW-SE BAROCLINIC ZONE STUCK OVER THE AREA. DSA && .AVIATION... FOR THE 0000 UTC KSGF/KJLN TAFS...ISOLATED TO WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO BE POSSIBLE OVERNIGHT...MAINLY ALONG A WEAK ELEVATED FRONT FROM THE KC METRO AREA SOUTHEAST INTO THE MO OZARKS. WILL CONTINUE TO CARRY SOME MENTION OF SHOWERS/VICINITY SHOWERS FOR KSGF OVERNIGHT. ANY PRECIP SHOULD BE BRIEF. WILL KEEP TAFS VFR...BUT MAY SEE SOME AFTERNOON/EARLY EVENING THUNDERSTORMS ONCE AGAIN WED...BUT PROBABILITY IS TOO LOW TO CARRY A MENTION IN THE TAFS FOR NOW. WE MAY SEE SOME REDUCTION IN VISIBILITY IN LIGHT FOG/HAZE AGAIN TOWARD DAWN. DSA .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 920 PM CDT TUE JUL 22 2008 .UPDATE... SCATTERED CONVECTION WILL CONTINUE TO BE POSSIBLE TONIGHT AS A MODEST LOW LEVEL S-SW FLOW CONTINUES TO PRODUCE SOME MODEST LIFT ALONG AN ELEVATED NW-SE FRONTAL BOUNDARY FROM NW MO INTO THE MO OZARKS. CAPES DEPICTED BY THE RUC STILL PRETTY STOUT OVER KS...WITH MLCAPES 2000+ J/KG. THIS WEAKENS INTO THE MO OZARKS... WITH MLCAPES OF 500-1500 J/KG...BUT MUCAPES STILL 1500-2000 J/KG. STILL HAVE ONE GOOD PERSISTENT UPDRAFT OVER EAST CENTRAL KS...AND A WEAKER CLUSTER OVER WEST CENTRAL MO. BELIEVE WE WILL SEE THIS ELEVATED CONVECTION CONTINUE FOR AWHILE INTO THE OVERNIGHT HOURS. MAY BE A SIMILAR STORY FOR THE COMING DAYS...WITH THE NW-SE BAROCLINIC ZONE STUCK OVER THE AREA. DSA && .AVIATION... FOR THE 0000 UTC KSGF/KJLN TAFS...OUTFLOW BOUNDARY HAS PUSHED CONVECTION WEST AND SOUTH OF THE TAFS SITES...BUT ACTUAL WEAK SFC BOUNDARY STILL EXTENDS FROM CENTRAL KS INTO THE MO OZARKS. WILL CONTINUE TO MONITOR FOR POSSIBLE REDEVELOPMENT ALONG AN ELEVATED FRONTAL BOUNDARY LATER TONIGHT FROM THE KC METRO AREA SOUTH INTO CENTRAL MO AND THE MO OZARKS. CAN`T RULE OUT SOME SHALLOW FOG WHERE HEAVIER RAIN FELL TODAY...BUT THE TAF SITES ESCAPED THE HEAVIER RAINFALL SO WILL LEAVE BOTH TAFS VFR THROUGH WED. DSA && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 255 AM CDT TUE JUL 22 2008 .DISCUSSION... STATIONARY SURFACE BOUNDARY WAS LOCATED JUST SOUTH OF THE NEBRASKA BORDER INTO NORTHERN MISSOURI THIS MORNING. MAIN AREA OF CONVECTION WAS LOCATED OVER NORTHEAST MISSOURI BUT ISOLATED CELLS HAVE BEEN DEVELOPING UPSTREAM JUST EAST OF KICL. SATELLITE SHOWING INCREASING MID CLOUDS FROM NEAR KICL TO NW OF KOMA AT 07Z. THIS AREA LINES UP WITH 00Z GFS QPF AT 12Z AND WITH 06Z RUC 850-700MB THETA-E AXIS WHICH GRADUALLY GETS PUSHED SOUTH THROUGH 18Z. WILL CARRY SOME LOW POPS THIS MORNING FOR SOUTHEASTERN PARTS OF THE CWA IN ASSOCIATION WITH THE THETA-E AXIS. AFTER THIS MORNING LOOKS LIKE AREA STAYS NORTH AND EAST OF THE MOISTURE AXIS FOR THE AFTERNOON AND TONIGHT AS SURFACE HIGH OVER THE UPPER GREAT LAKES BUILDS INTO THE MID MISSISSIPPI VALLEY. HIGH SHIFTS EAST ON WEDNESDAY WITH CHANCE POPS RETURNING TO THE AREA WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT. BOTH NAM AND GFS FOCUS AN MCS NEAR THE NEBRASKA SOUTH DAKOTA BORDER LATE WEDNESDAY NIGHT INTO THURSDAY MORNING WITH NAM FASTER IN MOVING IT EAST OF THE AREA. GENERALLY BROADBRUSHED POPS DUE TO UNCERTAINTY IN TIMING. TEMPERATURES NOT AS HOT FOR MOST OF THE AREA TODAY AND WEDNESDAY BUT DO RETURN THURSDAY THROUGH SATURDAY AS UPPER RIDGE REBUILDS OVER THE WEST. NO CHANGE TO THE EXTENDED PERIOD AT THIS TIME. && .AVIATION... FOR TAF SITES KOMA/KLNK/KOFK THRU 23/12Z FRONTAL BOUNDARY SUPPORTING CONVECTION HAS SHIFTED SOUTH OF EASTERN NEBRASKA TAF SITES...HOWEVER A BAND OF MID LEVEL MOISTURE AND RESIDUAL INSTABILITY MAY SPARK SCATTERED SHOWERS OR STORMS THROUGH 15Z IN EASTERN NEBRASKA. THESE SHOULD REMAIN ISOLATED AND NOT LIKELY TO DIRECTLY AFFECT TAF SITES. LOW LEVEL MOISTURE WILL BE SLOW TO LEAVE THE AREA...SO AREAS OF MVFR FOG ARE POSSIBLE IN THE FEW HOURS JUST BEFORE AND AFTER SUNRISE BOTH TUESDAY MORNING AND WEDNESDAY MORNING. OTHERWISE VFR CONDITIONS WITH ONLY SCATTERED AFTERNOON CUMULUS AND PASSING MID/HIGH CLOUDS EXPECTED. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ FOBERT/DERGAN ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTH PLATTE NE 312 PM CDT MON JUL 21 2008 .DISCUSSION... SFC FRONT HAS DRAPED THROUGH THE NORTH PLATTE VALLEY AND WEST THROUGH KBFF THIS AFTN. MOISTURE HAS GRADUALLY POOLING BEHIND THE FRONT AFTER LAST NIGHTS SEVERE WEATHER EVENT. CU FIELD IS DEVELOPING OVER ERN WY AND EAST ALONG THE FRONT SUGGESTING SUFFICIENT INSTABILITY FOR STORM DEVELOPMENT. STEERING CURRENTS WOULD LIKELY CARRY ANY DISTURBANCES EAST ALONG THE FRONT THROUGH THE SRN HALF OF THE FCST AREA TONIGHT. OVERALL...CONDITIONS APPEAR TO BE INCREASINGLY FAVORABLE FOR THUNDERSTORMS BUT THE GFS...NAM AND RUC ARE SILENT TONIGHT. THE MODELS INDICATE NO SUFFICIENT FORCING IS PRESENT TO BRING ORGANIZED RAINFALL TO WRN OR CNTL NEB TONIGHT. THE BLENDED GUIDANCE INDICATED ISOLATED STORMS ARE POSSIBLE AND THIS GUIDANCE WAS USED FOR POPS TONIGHT THROUGH WEDNESDAY. TUESDAY...THE FRONT WILL REMAIN STATIONARY THROUGH THE PLATTE VALLEY. THE NEIGHBORS TO THE WEST SUGGESTED SCATTERED STORMS COULD DEVELOP ACROSS THE PANHANDLE DURING THE AFTERNOON AND MOVE EAST OVERNIGHT INTO CNTL NEB. MOISTURE WILL CONTINUE POOL AND INCREASE. STILL... FORCING IS EXPECTED TO REMAIN INSUFFICIENT FOR ORGANIZED STORM DEVELOPMENT HOWEVER. THE OFFICIAL FORECAST IS FOR SLIGHTLY BETTER RAIN CHANCES...ISOLATED TO SCATTERED THUNDERSTORMS TUESDAY NIGHT. WEDNESDAY AND THURSDAY...THE ATM REACHES CRITICAL MASS. ALL MODELS INDICATE 140 PERCENT OR GREATER THAN NORMAL MOISTURE AND THE NAM INDICATES 175 PERCENT OF NORMAL. A WEAK DISTURBANCE WILL MOVE THROUGH THE NRN PLAINS WEDNESDAY WHICH COULD BE SUFFICIENT FOR A BIT MORE ORGANIZED STORM DEVELOPMENT. A SECOND DISTURBANCE IS PROGGED BY THE NAM12 ON THURSDAY. SPC HAS A 5 PERCENT SEVERE WEATHER PROBABILITY FOR TONIGHT THROUGH WEDNESDAY SUGGESTING ONLY ISOLATED SEVERE WEATHER PROBABILITIES AND HPC INDICATES 1/4 INCH RAINFALL FOR DAYS 1 THROUGH 5. THUS...ALTHOUGH MOISTURE AND THERMODYNAMICS SUPPORT STORM DEVELOPMENT...UPPER LEVEL FORCING WILL BE INSUFFICIENT FOR ORGANIZED THUNDERSTORM DEVELOPMENT. FRIDAY AND BEYOND...THE GFS SUGGESTS MOISTURE WILL CONTINUE IN PLACE THROUGH SUNDAY WITH THE ATM FINALLY DRYING OUT MONDAY. THE HPC GRIDS SUGGESTED MOSTLY ISOLATED THUNDERSTORM ACTIVITY AND THIS WAS SUPPORTED BY THE GFS...ECMWF AND ENSEMBLE GFS WHICH SHOW ISOLATED THUNDERSTORMS OR WEAKLY ORGANIZED CONVECTIVE DEVELOPMENT. THE GFS FAVORS THE MISSOURI BASIN FOR RAINFALL AND THE GFS FAVORS THE PLATTE VALLEY. THE TEMPERATURE FORECAST WAS THE USUAL BLENDED GUIDANCE WITH HPC FOR THE EXTENDED FORECAST. THE GFS ENSEMBLE SUGGESTED TEMPERATURES WILL REMAIN MORE OR LESS STATIC THROUGH THROUGH SUNDAY WITH A SLIGHT COOL DOWN MONDAY. THE HPC TEMPERATURES WERE MARKED UP SLIGHTLY TOWARD THE ENSEMBLE WHICH WAS RELATIVELY CLOSE TO THE VERY WARM 12Z GFS GUIDANCE IN SUPPORT OF THE WARMER ENSEMBLE SOLN. IN FINAL...ATMOSPHERIC CONDITIONS ARE QUITE FAVORABLE FOR THUNDERSTORM DEVELOPMENT BUT THE LACK OF UPPER LEVEL FORCING HAS PRECLUDED HIGHER POPS. LATER FORECASTS TONIGHT AND BEYOND WILL HAVE TO CLOSELY MONITOR CONDITIONS AS CIRCUMSTANCES COULD CHANGE DRAMATICALLY. IN OTHER WORDS...THE AMOSPHERE COULD CATCH FIRE. && .AVIATION... THE PROBABILITY FOR THUNDERSTORMS AT EITHER THE KVTN OR KLBF TERMINALS APPEARS TOO LOW TO MENTION IN THE LATEST TAF FCST. THOUGH A SFC FRONT COMBINED WITH A MOIST AND MODERATELY UNSTABLE ATMOSPHERE WILL BE LOCATED OVER THE SOUTHERN HALF OF NEBRASKA...UPPER LVL SUPPORT IS FCST TO BE DISPLACED FROM THOSE INGREDIENTS OVER WESTERN AND NORTH CENTRAL NEBRASKA...PRECLUDING STORM DEVELOPMENT. THUS...WE WILL BE DEALING WITH MAINLY PERIODIC SCT MID TO HIGH LVL CLOUD DECKS...WITH WINDS MAINTAINING AN EASTERLY COMPONENT THROUGH THE NEXT 24 HRS. && .LBF WATCHES/WARNINGS/ADVISORIES...NONE. && $$ CDC/JG ne AREA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE ALBUQUERQUE NM 315 PM MDT TUE JUL 22 2008 .DISCUSSION... LATEST RUC80 UPPER AIR ANALYSIS INDICATES TWO HIGH CENTROIDS OVER THE SOUTHWESTERN UNITED STATES. ONE CENTER IS POSITIONED AT THE CA/ AZ/BAJA OF CA TRIPLE POINT...WHILE THE OTHER IS CENTERED JUST EAST OF THE OK/TX PANHANDLES. THIS HAS ALLOWED FOR AN UPR LEVEL WEAKNESS ACROSS THE STATE OF NEW MEXICO. SHOWERS AND THUNDERSTORMS WILL BE MOST NUMEROUS OVER THE CENTRAL AND WRN ZONES...PARTICULARLY WITHIN THE 850-700MB THETA-E RIDGE AXIS. AS MENTIONED IN THE PREVIOUS AFD... A FEW THUNDERSTORMS WILL DEVELOP IN THE HIGH PLAINS...BUT STEERING FLOW WILL CURTAIL ITS EASTWARD PROGRESSION. AS TYPICAL THIS TIME OF YEAR...LOCALIZED FLOODING IS POSSIBLE WITH SLOW MOVING STORMS. MOST OF THE ACTIVITY WILL DIMINISH BEFORE THE MIDNIGHT HOUR...HOWEVER A FEW LINGERING STORMS COULD SURVIVE INTO THE EARLY MORNING. SIMILAR SITUATION IS EXPECTED FOR WEDNESDAY...WITH THE BEST THREAT FOR PCPN TO OCCUR OVER THE CENTRAL AND WRN ZONES. SOME ACTIVITY MAY TRY TO SQUEAK INTO THE NE PLAINS AS THE THETA-E RIDGE AXIS TILTS A BIT. TEMPERATURES WILL BE WARMEST OVER THE ERN PLAINS AS PCPN/CLOUD COVER LIMITS THE AMOUNT OF INCOMING SOLAR IN THE WEST. ALL EYES SHIFT TO THE GULF OF MEXICO FOR THE LATTER PORTION OF THE WEEK AS TROPICAL STORM...SOON TO BE HURRICANE...DOLLY APPROACHES SRN TEXAS. THE NAM80 HAS BEEN CONSISTENTLY ONE OF THE MORE NRN SOLUTIONS AND PROVIDES SOME IMPACT IN THE FORM OF INCREASED QPF ACROSS SRN NM. OF INTEREST...THREE OUT OF 13 HURRICANE MODELS TRACK THE REMAINS OF THE TROPICAL SYSTEM UP THE RIO GRANDE INTO SE NM. THOUGH UNLIKELY... IT BEARS WATCHING WHETHER THIS FEATURE WILL IMPACT THE CWA. ATTM... IT APPEARS THE GFDI MODEL AND TPC TRACK LOOK THE MOST PLAUSIBLE. IN GENERAL...THE BIGGEST PLAYER WILL BE THE POSITION OF THE UPPER HIGH. IN CONTRAST...THE GFS PLACES THE HIGH ON FRI OVER ERN NM/WRN TX... BLOCKING THE STATE FROM AN INTRUSION OF DEEP MOISTURE. MEANWHILE... THE ECMWF PLACES THE HIGH NEAR THE DALLAS AREA...ALLOWING FOR A S/SE COMPONENT ACROSS SRN NM. BY THE WEEKEND...THE GFS SHIFTS THE UPPER HIGH TO CENTRAL NM...SHUNTING THE REMAINS INTO THE EASTERN PACIFIC. THE ECMWF IS LESS AGGRESSIVE AND SHIFTS THE UPR HIGH ONLY TO CENTRAL TX...OPENING THE DOOR FOR TROPICAL MOISTURE TO MIGRATE INTO CENTRAL AZ. BASED ON THE AFOREMENTIONED UNCERTAINTY...WILL NOT MAKE SWEEPING CHANGES TO THE INHERITED MID/LONG RANGE FORECAST. DPORTER && .AVIATION... SCATTERED SHOWERS AND THUNDERSTORMS WILL MAINLY AFFECT THE WESTERN TWO THIRDS OF THE FORECAST AREA THROUGH THE NEXT 24 HOURS. THIS INCLUDES AFFECTS TO TERMINAL SITES SUCH AS GUP...FMN...ABQ AND SAF. MVFR AND SHORT DURATION IFR CONDITIONS WILL BE ASSOCIATED WITH THE STRONGER STORMS. CELL MOVEMENT WILL BE SLOW THUS MAKING THE POTENTIAL FOR LONGER MVFR CONDITIONS NEAR AIRPORTS. STRONG WIND GUSTS WILL ALSO BE ASSOCIATED WITH THE HEAVIEST RAIN ACTIVITY. GUSTS UP TO 40 KTS WILL BE POSSIBLE. NEXT AVIATION DISCUSSION SCHEDULED FOR 09Z. 50 && .FIRE WEATHER... UPPER HIGH WILL REMAIN CENTERED OVER A PORTION OF NEW MEXICO THROUGH AT LEAST THE WORK WEEK. ABUNDANT MOISTURE TRAPPED UNDERNEATH THIS UPPER HIGH WILL RECYCLE OUT IN THE FORM OF WETTING RAIN. THE FAVORED AREA FOR THIS WETTING RAIN WILL BE ACROSS WESTERN AND CENTRAL AREAS. THE EASTERN THIRD WILL SEE THE LEAST AMOUNT OF THUNDERSTORM ACTIVITY...IF ANYTHING AT ALL. TROPICAL STORM DOLLY WILL BE A FEATURE TO WATCH FOR LATE IN THE WEEK AND OVER THE WEEKEND. SOME OF HER MOISTURE COULD GET TRANSPORTED UP INTO NM BUT AT THIS TIME...A LITTLE LESS LIKELY FOR ANY SIGNIFICANT IMPACTS. WILL HAVE TO KEEP AN EYE ON IT. HUMIDITY IS EXPECTED TO REMAIN ABOVE 20 PCT THROUGH FRIDAY. 50 && .PRELIMINARY POINT TEMPS/POPS... FARMINGTON...................... 64 89 62 94 / 60 40 30 20 GALLUP.......................... 59 82 56 87 / 60 50 30 30 GRANTS.......................... 57 82 54 88 / 50 40 30 30 GLENWOOD........................ 64 88 62 92 / 40 50 30 30 CHAMA........................... 49 77 49 81 / 60 50 40 30 LOS ALAMOS...................... 55 83 55 86 / 30 30 30 20 RED RIVER....................... 45 73 45 74 / 30 30 30 30 TAOS............................ 53 85 49 88 / 30 30 30 20 SANTA FE........................ 57 85 59 88 / 40 30 30 20 SANTA FE AIRPORT................ 59 87 59 91 / 40 20 20 20 ESPANOLA........................ 60 89 58 94 / 30 30 30 20 ALBUQUERQUE HEIGHTS............. 67 90 68 92 / 40 20 20 20 ALBUQUERQUE VALLEY.............. 65 92 65 94 / 30 20 20 20 ALBUQUERQUE FOOTHILLS........... 63 88 64 91 / 40 20 20 20 ALBUQUERQUE WEST MESA........... 66 91 66 93 / 40 20 20 20 SOCORRO......................... 64 92 64 92 / 30 20 20 20 SANDIA PARK/CEDAR CREST......... 54 84 54 87 / 40 30 20 20 MORIARTY/ESTANCIA............... 57 87 58 89 / 30 20 20 20 CARRIZOZO....................... 60 90 62 92 / 30 20 20 20 RUIDOSO......................... 55 81 54 81 / 30 20 10 20 RATON........................... 56 90 56 91 / 10 10 10 10 LAS VEGAS....................... 56 86 56 86 / 20 20 20 20 ROY............................. 62 89 63 89 / 10 10 10 10 CLAYTON......................... 64 94 65 93 / 5 5 5 10 SANTA ROSA...................... 63 94 63 94 / 10 10 10 10 TUCUMCARI....................... 66 96 68 97 / 0 5 5 5 FORT SUMNER..................... 67 95 67 95 / 10 5 5 5 CLOVIS.......................... 66 94 68 93 / 0 5 5 5 PORTALES........................ 66 95 68 94 / 5 5 5 5 ROSWELL......................... 69 96 69 96 / 5 5 5 5 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 46/50 nm AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 946 PM EDT TUE JUL 22 2008 .SYNOPSIS... UPPER LEVEL LOW PRESSURE WILL CONTINUE TO DEVELOP ACROSS THE NORTHERN GREAT LAKES TONIGHT. AS THIS SYSTEM DEEPENS WEDNESDAY INTO THURSDAY...DEEP SUBTROPICAL MOISTURE TRANSPORTED NORTHWARD WILL BRING INCREASING CHANCES FOR HEAVY RAINFALL TO THE REGION. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... AS OF 940 PM EDT TUESDAY...LOCALIZED HEAVY RAINFALL HAS OCCURRED ONCE AGAIN THIS EVENING ASSOCIATED WITH SLOW MOVING CONVECTIVE CELLS WITH WARM RAIN PROCESSES DOMINATING. PER RADAR ESTIMATES...THE HEAVIEST RAINFALL AMTS HAVE BEEN IN WASHINGTON COUNTY JUST NORTH OF MPV...WITH ESTIMATES OF 1.5 TO 2 INCHES. ALSO...SEPARATE CONVECTIVE CELL ACROSS FAR SERN ORLEANS COUNTY PRODUCED 1.5 TO 2 INCHES OF RAINFALL BETWEEN WESTMORE AND SUTTON VERMONT. LOCALIZED POOR DRAINAGE FLOODING IS POSSIBLE IN THESE AREAS DURING THE NEXT 1-3 HOURS. ALTHOUGH 01Z LAPS CAPE ANALYSIS STILL INDICATES VALUES AROUND 500 J/KG ACROSS CENTRAL/NRN PORTIONS OF THE NORTH COUNTRY...POTENTIAL FOR LTG IN ISOLD/SCATTERED SHOWER ACTIVITY IS LIMITED BY RELATIVELY HIGH FREEZING LEVELS /13.2 KFT AT KALB PER 00Z RAOB/ AND NARROW NATURE OF CAPE PROFILE. FEEL CONFIDENT THAT REMAINING CONVECTIVE CELLS OVERNIGHT WILL BE FREE OF LIGHTNING AND WE WILL DROP THE LAKE THUNDERSTORM ADVISORY ON LAKE CHAMPLAIN AT THIS TIME. THE 850MB RUC ANALYSIS CONTINUES TO SHOW WEAK WAA ON SWLY FLOW AROUND 10 KTS EAST OF 850MB TROUGH AXIS ACROSS THE ERN GREAT LAKES. THIS COMBINED WITH MODERATELY HIGH PW VALUES AROUND 1.25 INCHES WILL MAINTAIN ISOLD/SCT CELLS OVERNIGHT...LARGELY LINKED TO OROGRAPHIC FORCING. AS SUCH...GREATEST COVERAGE SHOULD CONTINUE TO BE ACROSS THE NRN ADIRONDACKS AND N-CENTRAL/NERN VT. BRIEF PERIODS OF HEAVY RAINFALL REMAIN POSSIBLE WITH STRONGER CELLS. OTHERWISE...2-M WINDS WILL REMAIN NEARLY CALM WITH WEAK P-GRADIENT IN PLACE. SMALL PBL DEWPOINT DEPRESSIONS AND BREAKS IN OVERCAST WILL ALLOW FOR PATCHY FOG DEVELOPING AFTER MIDNIGHT. FOG WILL BE LOCALLY DENSE IN FAVORED VALLEY LOCATIONS...ESPECIALLY AREAS SEEING RAIN SHOWER ACTIVITY THIS EVENING. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/... AS OF 409 PM EDT TUESDAY...LATEST MODEL GUIDANCE CONTINUES TO SHOW GOOD AGREEMENT INDICATING AN INCREASING THREAT OF EXCESSIVE RAINFALL ACROSS MUCH OF OUR FORECAST AREA WEDNESDAY INTO THURSDAY. UPPER LOW WILL CONTINUE TO DEEPEN OVER THE GRTLKS TONIGHT/WED...AND WILL TAKE ON A NEUTRAL TO SLIGHTLY NEGATIVE TILT BY THURS. THIS WILL ALLOW A DEEP SUBTROPICAL MOISTURE PLUME TO DEVELOP ACROSS ERN NY AND NEW ENGLAND WED INTO THURS. COUPLED GULF OF MEXICO/WRN ATLC PLUMES TO CONVERGE ACROSS THE AREA DURING THIS PERIOD...WITH PWATS IN EXCESS OF 2 INCHES LIFTING SOUTH TO NORTH INTO FA. HEAVIEST RAIN EXPECTED LATER WED INTO THURS MORNING AS RATHER VIGOROUS SHRTWV ROUNDS BASE OF UPPER LOW AND INTERACTS WITH N-S SFC BOUNDARY APRCHG SLOWLY FROM THE WEST. DESPITE SOME DIFFERENCES IN NAM/GFS REGARDING DURATION OF THE EVENT...THEY ARE REMARKABLY SIMILAR AS TO WHERE THEY INDICATE MAX PCPN...SHOWING A WIDEPSREAD 2 TO 4 INCHES OF QPF OVER ERN NY AND WRN/CNTRL VT BTWN MIDDAY WED AND THURS PM...WITH NAM INDICATING SOME LOCALIZED 6"+ TOTALS. ANTECEDENT CONNDITIONS (3 TO 6 INCHES OF RAINFALL OVER PAST SEVERAL DAYS ACRS MUCH OF AREA) SUGGEST THIS AMOUNT OF EXPECTED RAIN WILL BE ENOUGH TO PRODUCE FLOODING ACROSS PORTIONS OF FA. HAVE THEREFORE ISSUED A FLOOD WATCH FOR ALL OF OUR CWA EXCEPT FOR ST LWR CTY AND NRN FRANKLIN CTY NY WHERE THREAT OF HVY RAIN IS LOWEST. NAM ALSO INDICATES THERE MAY BE A POTENTIAL WIND PROBLEM FOR WED NITE...MAINLY FOR HIR TRRN/WRN SLOPES OF VT. && .LONG TERM /FRIDAY THROUGH TUESDAY/... AS OF 2 PM TUESDAY...OTHER THAN A BREAK IN THE PRECIPITATION ON FRIDAY IT LOOKS LIKE A WET PATTERN WILL CONTINUE WITH TEMPERATURES NEAR OR SLIGHLY BELOW SEASONAL AVERAGES THROUGH THE PERIOD. MODELS CONTINUE TO BE IN AGREEMENT WITH THE LARGE SCALE LEADING TO DECENT FORECASTER CONFIDENCE THOUGH DETAILS AND TIMING VARY. UPPER TROF MOVES EAST OF THE REGION ON FRIDAY WITH VERY LITTLE CHANCE OF SHOWERS AND NEAR NORMAL TEMPERATURES. THINK MOS MAX TEMPS A BIT OVERDONE AS BEEN THE CASE LATELY. THINK THE WET PATTERN AND DAILY EVAPOTRANSPIRATION KEEPING BOUNDARY LAYER A BIT COOLER THAN WOULD ORDINARILY BE EXPECTED. ON SATURDAY UPPER TROF RELOADS AND A RETRIGGERING OF CONVECTION THAT COULD TURN INTO MORE HEAVY RAIN BY SATURDAY NIGHT INTO EARLY SUNDAY BUT JUST TOO SOON TO TELL. THE FRONT DOES LOOK A LITTLE MORE PROGRESSIVE SO PRECIP TAPERS TO POST FRONTAL CHANCES OF SHOWERS. COULD BE THUNDER BUT LEFT OUT FOR NOW AS COLD CORE ALOFT STAYS MAINLY NORTH. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... THROUGH 00Z THURSDAY....CONDITIONS SHOULD REMAIN VFR THROUGH MOST OF THE FIRST 24 HOURS. WIDELY SCATTERED RAIN SHOWERS SHOULD DISSIPATE AS THE SUN SETS AND EXPECT DRY CONDITIONS AND SCATTERED CLOUDS BY 01Z. FOG WILL SET IN AT ALL SITES...GENERALLY 07Z-11Z. KBTV/KPBG/KRUT WILL REMAIN MVFR IN OCCASIONAL FOG. KMPV/KSLK WILL BOTH SEE IFR VISIBILITY AND CEILINGS AFTER 05Z...THEN LIFR/VLIFR AFTER 08Z. FOG SHOULD LIFT AT ALL SITES BY 12Z. THEREAFTER...LOW CEILINGS AS UPPER LOW PRESSURE DEEPENS AND MOISTURE ADVECTS INTO THE AREA. GENERALLY EXPECT CEILINGS 2000-4000 FT 12Z-15Z...THEN MVFR AT ALL SITES AFTER 15Z AT ONSET OF RAIN SHOWERS. HEAVIER PRECIPITATION SHOULD MOVE IN AFTER 21Z...DROPPING VISIBILITY TO 4SM AND CEILINGS TO BELOW 2000 FT. WINDS WILL BE 10 KNOTS OR LESS FROM THE SOUTH TO SOUTHEAST. 00Z THURSDAY THROUGH SUNDAY...UNSETTLED WEATHER TO CONTINUE FOR MUCH OF THE EXTENDED AVIATION. HEAVY RAIN WILL PERSIST WEDNESDAY INTO THURSDAY MORNING...WITH WIDESPREAD MVFR AND SCATTERED IFR EXPECTED. LINGERING SHOWERS THURSDAY AFTERNOON SHOULD DISSIPATE OVERNIGHT...WITH FRIDAY DRY AND VFR. MORE RAIN EXPECTED FOR SATURDAY AND SUNDAY ESPECIALLY IN THE AFTERNOON. VFR CONDITIONS WITH OCCASIONAL MVFR IN SHOWERS AND THUNDERSTORMS OVER THE WEEKEND. && .HYDROLOGY... THE POTENTIAL FOR VERY HEAVY RAIN AND SERIOUS FLOODING EXISTS WED- THU. THIS EVENINGS SLOW MOVING SHOWERS AND EMBEDDED THUNDERSTORMS HAVE DROPPED NEARLY 2"/HR VIA GAGE AND MATCHING RADAR ESTIMATES JUST A SIGN OF THINGS TO COME. GFS/SREF/NAM MODELS CONSISTENTLY HIGHLIGHTING HEAVY RAIN THREAT SOMEWHERE OVER OUR FORECAST AREA FROM THE ADIRONDACKS/ESSEX EAST. INCREASING CONFIDENCE THAT A POTENTIALLY SIGNIFICANT AND EXCESSIVE RAINFALL EVENT IS ON TAP FOR OUR REGION BEGINNING WED MORNING AND CONTINUING INTO THURSDAY AFTERNOON. WITH HEAVY ANTECEDENT RAINFALL OF 3-6 INCHES AND POINT TOTALS NEARING 8 INCHES ACROSS CENTRAL AND NORTHERN AREAS OVER THE PAST 4 DAYS...HEADWATER 1/3/6 HR FFG VALUES ARE QUITE LOW AND IT WON/T TAKE MUCH TO PUSH STREAMS AND RIVERS INTO FLOOD SHOULD ADDL HEAVY RAFL OCCUR. CONSERVATIVE ESTIMATES WOULD BRING WIDESPREAD 1-3 INCH AND SCT 4 INCH TOTALS TO MUCH OF OUR REGION DURING THE WED/THU PERIOD AS SEMI-STATIONARY DEEP SUBTROPICAL MOISTURE PLUME RIDES NORTH ACROSS OUR AREA. HIGH END ESTIMATES WOULD GIVE SOME AREAS UP TO 7 INCHES DURING THESE PERIODS...WHICH MAY SOMEWHAT OVERDONE AREALLY BUT CERTAINLY POSSIBLE SHOULD THE MOISTURE PLUME SHOW MORE STATIONARITY. IF THESE TOTALS INDEED OCCURRED FLOODING WOULD BE QUITE SERIOUS. && .EQUIPMENT... THE MASSENA ASOS UNDERGOING SERVICE TODAY AFTER THE SITE HAS BEEN REBUILT AND MAY BE AVAILABLE IN THE NEXT DAY OR SO. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...FLOOD WATCH FROM WEDNESDAY AFTERNOON THROUGH THURSDAY AFTERNOON FOR VTZ001>012-016>019. NY...FLOOD WATCH FROM WEDNESDAY AFTERNOON THROUGH THURSDAY AFTERNOON FOR NYZ028-030-031-034-035. && $$ SYNOPSIS...JMG NEAR TERM...BANACOS SHORT TERM...RJS LONG TERM...SISSON AVIATION...MB HYDROLOGY... EQUIPMENT... ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 650 PM EDT TUE JUL 22 2008 .SYNOPSIS...A WEAK SURFACE BOUNDARY OVER THE AREA AND A WARM HUMID AIR MASS WILL RESULT IN MUGGY CONDITIONS TONIGHT WITH A SLIGHT CHANCE OF A SHOWER OR THUNDERSTORM...MAINLY EAST OF HIGHWAY 1 AFTER MIDNIGHT. THE THREAT FOR THUNDERSTORMS WILL INCREASE WEDNESDAY AFTERNOON AS AN AREA OF LOW PRESSURE APPROACHES FROM THE WEST. && .NEAR TERM /THROUGH TONIGHT/... AS OF 650 PM TUESDAY... THE HEAT ADVISORY WILL EXPIRE AT 700 PM. SHOWERS AND THUNDERSTORMS CONTINUE ACROSS THE AREA IN RESPONSE TO WARM MOIST CONDITIONS AND SEVERAL BOUNDARIES ACROSS THE REGION. -RHJ PREVIOUS DISCUSSION... SFC ANALYSIS THIS AFTERNOON SHOWS A TROUGH AXIS STRETCHING FROM NJ SOUTHWEST THROUGH THE CENTRAL CAROLINAS INTO GA. WEAK HIGH PRESSURE WAS LOCATED JUST WEST OF THE MOUNTAINS OVER EASTERN TN/KY AND WV. A WEAK COLD FRONT WAS LOCATED FURTHER NORTHWEST ACROSS IA/IL/IN/OH. A LARGE OUTFLOW BOUNDARY ASSOC/W AN MCS THAT BARRELED THROUGH THE OHIO VALLEY INTO WV DURING THE OVERNIGHT HOURS MADE ITS WAY INTO CENTRAL NC DURING THE MORNING...STALLING OUT IN VICINITY OF THE US 1 CORRIDOR (NOTICE THE PROMINENT WIND SHIFT IN THAT AREA). ALOFT...12Z RAOB ANALYSIS SHOWED AN UPPER LOW WELL NORTH OF THE GREAT LAKES IN QUEBEC...WITH A LONGWAVE TROUGH AXIS STRETCHING SOUTHWEST THROUGH THE GREAT LAKES INTO MO/AR. THE BEST DYNAMICS ALOFT WERE ASSOC/W 30-40 METER 12-HR HEIGHT FALLS AND A 75-100 KNOT JET ENTRANCE REGION OVER THE EASTERN OHIO VALLEY INTO NORTHERN WV/VA AND PA. A WEAK SHORTWAVE TROUGH WAS NOTED AT 250MB JUST WEST OF THE SOUTHERN APPALACHIANS ACROSS EASTERN TN/KY/AL. AT 500MB...THERE WAS WEAK DIFFLUENCE ACROSS THE CAROLINAS. CONVECTION: THE 12Z GSO SOUNDING IS SPORTING SOME PRETTY STEEP LAPSE RATES... NEAR DRY ADIABATIC THROUGH 550MB...WITH A PWAT OF 1.31". FCST SOUNDINGS THIS AFTERNOON CONTINUE TO SHOW VERY STEEP LOW/MID LEVEL LAPSE RATES...WITH SFC DEWPOINTS IN THE MID/UPPER 60S. FCST SOUNDINGS ARE SHOWING QUITE A BIT OF AVAILABLE INSTABILITY THIS AFTERNOON WITH TEMPS EXPECTED TO REACH INTO THE UPPER 90S TO NEAR 100F. THE BIG QUESTION TODAY IS WHETHER OR NOT WE WILL HAVE A SUFFICIENT FOCUS FOR SCATTERED CONVECTION TO DEVELOP. AT PRESENT...THE REMNANT MCS OUTFLOW BOUNDARY STALLED OUT AROUND THE US 1 CORRIDOR IS A GOOD CANDIDATE FOR A LOW LEVEL FOCUS. THE WEAK 250MB SHORTWAVE JUST WEST OF THE MOUNTAINS IS ANOTHER CANDIDATE FOR CONVECTIVE SUPPORT...AT THE UPPER LEVELS. HOWEVER...THE LATEST RUC IS NOT SHOWING MUCH IN THE WAY OF LIFT IN ASSOC/W THIS FEATURE OVER CENTRAL NC...KEEPING THE BEST DPVA (ASSOC/W A 15/S VORTMAX) FURTHER SOUTH OVER GA/SC. ANOTHER POTENTIAL SOURCE OF LOW LEVEL LIFT MAY COME FROM THE SEABREEZE...DEPENDING ON HOW FAR INLAND IT PROPAGATES. GIVEN STRONG DIURNAL HEATING...IT SHOULD BE ABLE TO HEAD RELATIVELY FAR INLAND...AS MUCH AS LIGHT SOUTHWEST (COAST PARALLEL) LOW LEVEL WINDS WILL ALLOW. HAVE DECIDED TO DROP POPS IN THE TRIAD TO 20% GIVEN THAT THEY ARE COOLER/DRIER THAN ANYWHERE ELSE...AND ARE BEHIND THE STALLED OUTFLOW BOUNDARY. HAVE KEPT POPS AT LOW CHANCE (30%) CLOSER TO THE TRIANGLE AND SANDHILLS WHERE TEMPS/MOISTURE ARE HIGHER...AND UPPED POPS TO 40% IN THE COASTAL PLAIN WHERE THE STALLED MCS OUTFLOW BOUNDARY MAY MEET WITH OUTFLOW BOUNDARIES FROM DEEP CONVECTION CURRENTLY OVER FAR EASTERN NC AND/OR THE SEABREEZE...SHOULD IT PROPAGATE FAR ENOUGH INLAND THIS AFTERNOON. ANY STORMS THAT DO DEVELOP THIS AFTERNOON COULD EASILY BECOME SEVERE GIVEN THE VERY STEEP LOW/MID LEVEL LAPSE RATES...WITH A PRIMARY THREAT OF DAMAGING WINDS IN EXCESS OF 60 MPH AND HAIL UP TO THE SIZE OF NICKELS. TONIGHT...LOW TEMPERATURES EXPECTED TO BE VERY MILD IN THE LOWER/MID 70S. WILL INTRODUCE A SLIGHT CHANCE OF SHOWERS/STORMS OVERNIGHT TO TAKE INTO ACCOUNT ANY ACTIVITY THAT MAY PERSIST WELL PAST SUNSET AND/OR PROPAGATE INTO CENTRAL NC FROM THE NORTH OR WEST...BASED ON THE LATEST GFS/NAM RUNS WHICH SHOW A POTENTIAL FOR THIS TO OCCUR...IN ADDITION TO THE LATEST RADAR IMAGERY SHOWING CONVECTION DEVELOPING UPSTREAM OVER CENTRAL/EASTERN TN...WITH FCST SOUNDINGS SHOWING ENOUGH ELEVATED INSTABILITY TO SUPPORT CONVECTION THROUGHOUT THE OVERNIGHT HOURS. -VINCENT && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 300 PM TUESDAY... WEDNESDAY/WEDNESDAY NIGHT...VERY MOIST (PRECIP WATER VALUES AROUND 2 INCHES)...APPROACH OF A MID/UPPER LEVEL TROUGH...AND INCREASING DIVERGENCE ALOFT (ESPECIALLY AFTER 18Z) SUGGEST A LIKELIHOOD OF SCATTERED TO NUMEROUS THUNDERSTORMS. NAM/WRF IS A LITTLE FASTER THAN SLOWER GFS WHILE 00Z ECMWF APPEARS TO BE A GOOD COMPROMISE. NAM/WRF DOES APPEAR TO BE VERIFYING BETTER AT MID DAY WITH THE PLACEMENT/DYNAMICS FOR CONVECTION OCCURRING OVER THE MID MS VALLEY INTO THE WESTERN TN VALLEY (GFS LOOKS TOO SLOW AND TOO WEAK OVER THE MO BOOTHEEL INTO WESTERN KY/TN). WHILE LOW/MID LEVEL KINEMATICS RATHER WEAK...PRECIP LOADING IN THE STRONG UPDRAFTS MAY LEAD TO DAMAGING WET MICROBURSTS. IN ADDITION...CONVECTIVE INSTABILITY PARAMETERS SUGGEST THAT STORMS MAY PRODUCE CONTINUOUS TO EXCESSIVE AMOUNT OF LIGHTNING (K INDICES NEAR 40 DEG C; LOW LEVEL THETA-E AXIS OVER CWA; MUCAPE BETWEEN 2000-2500 J/KG ALONG AND EAST OF HIGHWAY 1). INITIATION OF CONVECTION WILL DETERMINE MAX TEMPS. IF TIMING OF GFS IS MORE CORRECT...CONVECTION WILL START MUCH LATER ALLOWING TEMPS TO WARM AT LEAST INTO THE MID 90S. SINCE FAVOR THE NAM TIMING...LEANED TOWARD THE COOLER ETA MOS GUIDANCE. WITH APPROACH OF MID LEVEL TROUGH WEDNESDAY NIGHT...EXPECT CONVECTION TO CONTINUE THROUGH THE EVENING AND INTO THE OVERNIGHT HOURS. THURSDAY...NAM/WRF MORE AGGRESSIVE WITH THE EWD PASSAGE OF MID LEVEL TROUGH THAN GFS/ECMWF. FAVOR THE SLOWER GFS AS DIFFICULT TO GET A "CLEAN" TROUGH PASSAGE THIS TIME OF YEAR. BEST POTENTIAL FOR CONVECTION WILL BE EAST OF HIGHWAY 1 WHERE DEEPER MOISTURE AND BEST INSTABILITY WILL RESIDE. FRIDAY...AIR MASS WILL BE CONDITIONALLY UNSTABLE (PER GFS). MID LEVEL LAPSE RATES UNIMPRESSIVE BUT PRECIP WATER VALUES WILL BE FAIRLY CLOSE TO NORMAL (1.3-1.5 INCHES) AND BOUNDARY LAYER LIFTED INDICES MINUS 2 TO MINUS 3. WILL CARRY A SLIGHT CHANCE POPS DURING THE HEAT OF THE DAY. THICKNESSES SUPPORT TEMPS CLOSE TO NORMAL (NEAR 90/LOWER 90S). && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... AS OF 210 PM TUESDAY... WEAK UPPER LEVEL TROUGH AND ATTENDANT SURFACE TROUGH WILL RESIDE OVER THE FORECAST AREA THROUGH THE PERIOD WITH THE POTENTIAL FOR SOME AMPLIFICATION OF THE UPPER TROUGH BY EARLY NEXT WEEK. THIS TYPE OF PATTERN USUALLY SUPPORTS A SLIGHT TO SMALL CHANCE OF DIURNAL CONVECTION WITH TEMPS HOVERING NEAR NORMAL. CAVEAT TO THIS IS THAT WITH NW MID/UPPER LEVEL FLOW...POTENTIAL FOR DECAYING MCS OR MCS INDUCED VORT MAX TO AFFECT THE REGION FROM ANY CONVECTION THAT DEVELOPS IN THE MID/UPPER MS VALLEY OR THE LOWER GREAT LAKES. THIS IS DIFFICULT TO FORECAST THIS FAR OUT...SO WILL KEEP POPS AOB 30% FOR NOW. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... AS OF 200 PM TUESDAY... BRIEF IFR/MVFR CONDITIONS IN ISOLATED SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING...THEN MVFR FOG AND HAZE WEDNESDAY MORNING. A TRICKY FORECAST REGARDING THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING. AT THIS TIME...THE BEST CHANCE FOR SHOWER/STORM ACTIVITY IS EXPECTED AT THE RWI/FAY TAF SITES...WITH A LESSER CHANCE AT RDU AND THE LEAST CHANCE AT INT/GSO. SEE NEAR TERM DISCUSSION FOR MORE DETAIL ON THE CONVECTIVE CHANCES. AT THIS TIME WILL COVER THE POTENTIAL FOR CONVECTION BY ADDING A SCT060CB TO ALL TAF SITES BETWEEN 20Z AND 02Z THIS AFTERNOON/EVENING. ISOLD SHOWERS/STORMS WILL BE POSSIBLE THROUGHOUT THE OVERNIGHT PERIOD...HOWEVER...CHANCES ARE TOO LOW TO INCLUDE MENTION IN THE TAFS AT THIS TIME. THE SAME AIR MASS OVERHEAD WILL RESULT IN AREAS OF MVFR HAZE AND FOG AGAIN ON WEDNESDAY MORNING. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED WEDNESDAY AFTERNOON AND EVENING AS A COLD FRONT MOVES INTO OUR REGION FROM THE NORTHWEST. LINGERING LOW LEVEL MOISTURE IN THE COASTAL PLAIN MAY ALSO PROMOTE MVFR/IFR FOG DEVELOPMENT AT KRWI AND KFAY EACH MORNING THURSDAY THROUGH SATURDAY. -VINCENT/MWS && .RAH WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR NCZ009>011- 024>028-040>043-073>078-083>086-088-089. && $$ SYNOPSIS...WSS/RHJ NEAR TERM...VINCENT/RHJ SHORT TERM...WSS LONG TERM...WSS AVIATION...VINCENT nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 211 PM EDT TUE JUL 22 2008 .SYNOPSIS... AFTERNOON HIGH TEMPERATURES IN THE UPPER 90S TO NEAR 100 ARE FORECAST FOR TODAY. CHANCES FOR THUNDERSTORMS TODAY WILL INCREASE WEDNESDAY AS A LOW PRESSURE TROUGH SLOWLY MOVED THROUGH THE AREA. && .NEAR TERM /THROUGH TONIGHT/... AS OF 200 PM TUESDAY... ...HEAT ADVISORY IN EFFECT THROUGH 7 PM IN PORTIONS OF CENTRAL NC...SEE TEMPERATURE DISCUSSION BELOW FOR MORE DETAILS... SFC ANALYSIS THIS AFTERNOON SHOWS A TROUGH AXIS STRETCHING FROM NJ SOUTHWEST THROUGH THE CENTRAL CAROLINAS INTO GA. WEAK HIGH PRESSURE WAS LOCATED JUST WEST OF THE MOUNTAINS OVER EASTERN TN/KY AND WV. A WEAK COLD FRONT WAS LOCATED FURTHER NORTHWEST ACROSS IA/IL/IN/OH. A LARGE OUTFLOW BOUNDARY ASSOC/W AN MCS THAT BARRELED THROUGH THE OHIO VALLEY INTO WV DURING THE OVERNIGHT HOURS MADE ITS WAY INTO CENTRAL NC DURING THE MORNING...STALLING OUT IN VICINITY OF THE US 1 CORRIDOR (NOTICE THE PROMINENT WIND SHIFT IN THAT AREA). ALOFT...12Z RAOB ANALYSIS SHOWED AN UPPER LOW WELL NORTH OF THE GREAT LAKES IN QUEBEC...WITH A LONGWAVE TROUGH AXIS STRETCHING SOUTHWEST THROUGH THE GREAT LAKES INTO MO/AR. THE BEST DYNAMICS ALOFT WERE ASSOC/W 30-40 METER 12-HR HEIGHT FALLS AND A 75-100 KNOT JET ENTRANCE REGION OVER THE EASTERN OHIO VALLEY INTO NORTHERN WV/VA AND PA. A WEAK SHORTWAVE TROUGH WAS NOTED AT 250MB JUST WEST OF THE SOUTHERN APPALACHIANS ACROSS EASTERN TN/KY/AL. AT 500MB...THERE WAS WEAK DIFFLUENCE ACROSS THE CAROLINAS. TODAY: THE TEMPERATURE AND CONVECTIVE FORECAST THIS AFTERNOON IS PRETTY CHALLENGING...DUE PRIMARILY TO THE LARGE MCS THAT PROPAGATED INTO THE MOUNTAINS DURING THE OVERNIGHT HOURS. THE OUTFLOW BOUNDARY FROM THE REMNANT MCS STALLED OUT ACROSS CENTRAL NC THIS MORNING. THE FORECAST IS AS FOLLOWS: CONVECTION: THE 12Z GSO SOUNDING IS SPORTING SOME PRETTY STEEP LAPSE RATES... NEAR DRY ADIABATIC THROUGH 550MB...WITH A PWAT OF 1.31". FCST SOUNDINGS THIS AFTERNOON CONTINUE TO SHOW VERY STEEP LOW/MID LEVEL LAPSE RATES...WITH SFC DEWPOINTS IN THE MID/UPPER 60S. FCST SOUNDINGS ARE SHOWING QUITE A BIT OF AVAILABLE INSTABILITY THIS AFTERNOON WITH TEMPS EXPECTED TO REACH INTO THE UPPER 90S TO NEAR 100F. THE BIG QUESTION TODAY IS WHETHER OR NOT WE WILL HAVE A SUFFICIENT FOCUS FOR SCATTERED CONVECTION TO DEVELOP. AT PRESENT...THE REMNANT MCS OUTFLOW BOUNDARY STALLED OUT AROUND THE US 1 CORRIDOR IS A GOOD CANDIDATE FOR A LOW LEVEL FOCUS. THE WEAK 250MB SHORTWAVE JUST WEST OF THE MOUNTAINS IS ANOTHER CANDIDATE FOR CONVECTIVE SUPPORT...AT THE UPPER LEVELS. HOWEVER...THE LATEST RUC IS NOT SHOWING MUCH IN THE WAY OF LIFT IN ASSOC/W THIS FEATURE OVER CENTRAL NC...KEEPING THE BEST DPVA (ASSOC/W A 15/S VORTMAX) FURTHER SOUTH OVER GA/SC. ANOTHER POTENTIAL SOURCE OF LOW LEVEL LIFT MAY COME FROM THE SEABREEZE...DEPENDING ON HOW FAR INLAND IT PROPAGATES. GIVEN STRONG DIURNAL HEATING...IT SHOULD BE ABLE TO HEAD RELATIVELY FAR INLAND...AS MUCH AS LIGHT SOUTHWEST (COAST PARALLEL) LOW LEVEL WINDS WILL ALLOW. HAVE DECIDED TO DROP POPS IN THE TRIAD TO 20% GIVEN THAT THEY ARE COOLER/DRIER THAN ANYWHERE ELSE...AND ARE BEHIND THE STALLED OUTFLOW BOUNDARY. HAVE KEPT POPS AT LOW CHANCE (30%) CLOSER TO THE TRIANGLE AND SANDHILLS WHERE TEMPS/MOISTURE ARE HIGHER...AND UPPED POPS TO 40% IN THE COASTAL PLAIN WHERE THE STALLED MCS OUTFLOW BOUNDARY MAY MEET WITH OUTFLOW BOUNDARIES FROM DEEP CONVECTION CURRENTLY OVER FAR EASTERN NC AND/OR THE SEABREEZE...SHOULD IT PROPAGATE FAR ENOUGH INLAND THIS AFTERNOON. ANY STORMS THAT DO DEVELOP THIS AFTERNOON COULD EASILY BECOME SEVERE GIVEN THE VERY STEEP LOW/MID LEVEL LAPSE RATES...WITH A PRIMARY THREAT OF DAMAGING WINDS IN EXCESS OF 60 MPH AND HAIL UP TO THE SIZE OF NICKELS. TEMPERATURES: TEMPS THIS AFTERNOON WILL DEPEND ON HOW MUCH CLOUD COVER/CONVECTION DEVELOPS ACROSS THE AREA THIS AFTERNOON. CURRENT INDICATIONS ARE THAT AREAS FROM THE TRIANGLE SOUTH/EAST SHOULD HAVE NO PROBLEM MAKING IT INTO THE UPPER 90S TO NEAR 100F THIS AFTERNOON BASED ON THICKNESSES AND MOS GUIDANCE...WHILE THE TRIAD AREA MAY TOP OUT IN THE MID 90S...DEPENDING HOW MUCH AIRMASS MODIFICATION OCCURRED IN ASSOC/W THE MCS OUTFLOW BOUNDARY PASSAGE. DEWPOINTS REMAIN IN THE UPPER 60S TO LOWER 70S ACROSS THE HEAT ADVISORY AREA AS OF 17Z... WITH HEAT INDEX VALUES ALREADY BETWEEN 100-104F. THE HEAT ADVISORY WILL REMAIN IN EFFECT UNTIL 700 PM THIS EVENING. TONIGHT...LOW TEMPERATURES EXPECTED TO BE VERY MILD IN THE LOWER/MID 70S. WILL INTRODUCE A SLIGHT CHANCE OF SHOWERS/STORMS OVERNIGHT TO TAKE INTO ACCOUNT ANY ACTIVITY THAT MAY PERSIST WELL PAST SUNSET AND/OR PROPAGATE INTO CENTRAL NC FROM THE NORTH OR WEST...BASED ON THE LATEST GFS/NAM RUNS WHICH SHOW A POTENTIAL FOR THIS TO OCCUR...IN ADDITION TO THE LATEST RADAR IMAGERY SHOWING CONVECTION DEVELOPING UPSTREAM OVER CENTRAL/EASTERN TN...WITH FCST SOUNDINGS SHOWING ENOUGH ELEVATED INSTABILITY TO SUPPORT CONVECTION THROUGHOUT THE OVERNIGHT HOURS. -VINCENT && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 300 AM TUESDAY... MID AND UPPER LEVEL TROUGHS DROP THROUGH THE OHIO VALLEY LATE TONIGHT AND WEDNESDAY...WITH WEST TO SOUTHWEST MID LEVEL WINDS OVER NORTH CAROLINA INCREASING TO 15 TO 30 KNOTS BY LATE AFTERNOON WEDNESDAY. LIKELY RAIN CHANCES BY WEDNESDAY AFTERNOON WITH HEAVIER RAINFALL AMOUNTS MORE LIKELY NEAR AND NORTH OF HIGHWAY 64. CHANCES FOR SHOWERS OR THUNDERSTORMS WILL CONTINUE INTO WEDNESDAY NIGHT. THE LATEST NAM...ECMWF AND GFS MODEL RUNS HAVE SIGNIFICANTLY ADVANCED THE MID LEVEL TROUGH POSITION THURSDAY MORNING... TO WHERE THURSDAY COULD TURN OUT ENTIRELY DRY. THE CANADIAN AND NAVY NOGAPS CONTINUE SLOWER WITH THIS TROUGH AND LINGER RAIN CHANCES OVER CENTRAL NORTH CAROLINA...AT LEAST IN THE EAST HALF. CONFIDENT ENOUGH TO REMOVE RAIN FROM THE WEST FOR THURSDAY...BUT WILL DELAY DRYING OUT THE EAST UNTIL NEAR SUNSET. IF THE MORNING MODELS CONFIRM THE DRYING TREND...THE EAST MAY END UP BEING DRY THURSDAY AS WELL. CURRENT FORECAST TEMPERATURES ARE ACCEPTED. MORNING LOWS 68 TO 73. AFTERNOON HIGHS 88 TO 93. -RLH && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 410 AM TUESDAY... INITIALLY WEST NORTHWEST FLOW ALOFT FRIDAY THROUGH SATURDAY WILL BACK TO WEST SOUTHWESTERLY IN RESPONSE TO A DEEPENING VORTEX OVER SOUTHERN ONTARIO AND QUEBEC SUNDAY INTO THE FIRST OF NEXT WEEK. THIS SHOULD RESULT IN A BROAD LOW LEVEL WARM MOIST ADVECTION AND MCS BEARING REGIME FROM THE MID MS VALLEY TO THE MID ATLANTIC STATES THROUGH SATURDAY... IN THE CONFLUENT FLOW TO THE WEST OF THE LONGWAVE TROUGH ATTENDANT THE SOUTHERN CANADA VORTEX. THEN AS THE TROUGH ALOFT SHARPENS... ADDED LIFT FROM THE UPPER JET MAY CREEP CLOSE ENOUGH TO ENHANCE PRECIPITATION CHANCES SUNDAY THROUGH MONDAY. THUS...INITIALLY DRY AND SUBSIDENT AIR ON FRIDAY -- IN THE WAKE OF THE TROUGH FROM THE SHORT TERM -- MAY MOISTEN RATHER QUICKLY FROM THE WEST FRIDAY EVENING/NIGHT... AS THE AFOREMENTIONED THETA-E ADVECTION AND LOW AMPLITUDE IMPULSES ALOFT (PERHAPS IN THE FORM OF AN MCV) PROVIDE FOR LARGE SCALE ASCENT OVER OUR REGION. WILL ACCORDINGLY DELAY POPS FOR MOST OF THE DAY FRIDAY WHEN THE SUBSIDENCE INVERSION LINGERS... THEN CARRY A CHANCE POP INTO THE LATE EVENING HOURS TO ACCOUNT FOR THE POSSIBLE ARRIVAL OF MCS RESIDUALS FROM THE TN VALLEY. THIS TREND OF RESIDUAL MCS ACTIVITY OR RENEWED DEEP CONVECTIVE DEVELOPMENT OVER OUR REGION FROM UPSTREAM MCV`S OR DIFFICULT TO TIME LOW AMPLITUDE BAROCLINIC WAVES/SHORTWAVE TROUGHS ALOFT WILL THEN CONTINUE THROUGH THE PERIOD... AS WE REMAIN IN A RELATIVELY MOIST AND CONDITIONALLY UNSTABLE AIR MASS. TEMPERATURES THROUGH THE PERIOD SHOULD RANGE FROM THE UPPER 80S TO LOWER 90S FOR HIGHS AND WITHIN A FEW DEGREES EITHER SIDE OF 70 DEGREES FOR LOWS. -MWS && .AVIATION /18Z TUESDAY THROUGH SATURDAY/... AS OF 200 PM TUESDAY... BRIEF IFR/MVFR CONDITIONS IN ISOLATED SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING...THEN MVFR FOG AND HAZE WEDNESDAY MORNING. A TRICKY FORECAST REGARDING THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING. AT THIS TIME...THE BEST CHANCE FOR SHOWER/STORM ACTIVITY IS EXPECTED AT THE RWI/FAY TAF SITES...WITH A LESSER CHANCE AT RDU AND THE LEAST CHANCE AT INT/GSO. SEE NEAR TERM DISCUSSION FOR MORE DETAIL ON THE CONVECTIVE CHANCES. AT THIS TIME WILL COVER THE POTENTIAL FOR CONVECTION BY ADDING A SCT060CB TO ALL TAF SITES BETWEEN 20Z AND 02Z THIS AFTERNOON/EVENING. ISOLD SHOWERS/STORMS WILL BE POSSIBLE THROUGHOUT THE OVERNIGHT PERIOD...HOWEVER...CHANCES ARE TOO LOW TO INCLUDE MENTION IN THE TAFS AT THIS TIME. THE SAME AIR MASS OVERHEAD WILL RESULT IN AREAS OF MVFR HAZE AND FOG AGAIN ON WEDNESDAY MORNING. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED WEDNESDAY AFTERNOON AND EVENING AS A COLD FRONT MOVES INTO OUR REGION FROM THE NORTHWEST. LINGERING LOW LEVEL MOISTURE IN THE COASTAL PLAIN MAY ALSO PROMOTE MVFR/IFR FOG DEVELOPMENT AT KRWI AND KFAY EACH MORNING THURSDAY THROUGH SATURDAY. -VINCENT/MWS && .RAH WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR NCZ009>011- 024>028-040>043-073>078-083>086-088-089. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...RLH LONG TERM...MWS AVIATION...VINCENT/MWS nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1035 AM EDT TUE JUL 22 2008 .SYNOPSIS... HOT CONDITIONS EXPECTED THIS AFTERNOON WITH TEMPERATURES APPROACHING THE CENTURY MARK. A LOW CHANCE OF SHOWERS AND THUNDERSTORMS ARE EXPECTED THIS AFTERNOON THROUGH THIS EVENING. && .NEAR TERM /THIS AFTERNOON THROUGH TONIGHT/... AS OF 1030 AM TUESDAY... SFC ANALYSIS THIS MORNING SHOWS A TROUGH AXIS STRETCHING FROM NJ SOUTHWEST THROUGH THE CENTRAL CAROLINAS INTO GA. WEAK HIGH PRESSURE WAS LOCATED JUST WEST OF THE MOUNTAINS OVER EASTERN TN/KY AND WV. A WEAK COLD FRONT WAS LOCATED FURTHER NORTHWEST ACROSS IA/IL/IN/OH. A LARGE OUTFLOW BOUNDARY ASSOC/W AN MCS THAT BARRELED THROUGH THE OHIO VALLEY INTO WV DURING THE OVERNIGHT HOURS WAS LOCATED OVER THE SOUTHWEST VA MOUNTAINS...HEADED SOUTHEAST DIRECTLY TOWARD CENTRAL NC. DEWPOINTS ACROSS CENTRAL NC RANGED FROM THE MID 60S TO LOWER 70S. ALOFT...12Z RAOB ANALYSIS SHOWED AN UPPER LOW WELL NORTH OF THE GREAT LAKES IN QUEBEC...WITH A LONGWAVE TROUGH AXIS STRETCHING SOUTHWEST THROUGH THE GREAT LAKES INTO MO/AR. THE BEST DYNAMICS ALOFT WERE ASSOC/W 30-40 METER 12-HR HEIGHT FALLS AND A 75-100 KNOT JET ENTRANCE REGION OVER THE EASTERN OHIO VALLEY INTO NORTHERN WV/VA AND PA. A WEAK SHORTWAVE TROUGH WAS NOTED AT 250MB JUST WEST OF THE SOUTHERN APPALACHIANS ACROSS EASTERN TN/KY/AL. AT 500MB...THERE WAS WEAK DIFFLUENCE ACROSS THE CAROLINAS. AT 850MB...THERE WAS DECENT SPEED CONVERGENCE ACROSS NORTHERN/WESTERN NC (RNK 30KT NORTHWEST WIND...GSO 10KT WESTERLY WIND). TODAY: THE TEMPERATURE AND CONVECTIVE FORECAST THIS AFTERNOON IS PRETTY CHALLENGING...DUE PRIMARILY TO THE LARGE MCS THAT PROPAGATED INTO THE MOUNTAINS DURING THE OVERNIGHT HOURS. THE REMNANT OUTFLOW BOUNDARY CONTINUES TOWARD CENTRAL NC AS OF 14Z...AND WAS LOCATED SOMEWHERE NEAR THE INTERFACE OF THE MOUNTAINS/FOOTHILLS OF SOUTHWEST VA AND NORTHWEST NC. THE FORECAST IS AS FOLLOWS: CONVECTION: THE 12Z GSO SOUNDING IS SPORTING SOME PRETTY STEEP LAPSE RATES... NEAR DRY ADIABATIC THROUGH 550MB...WITH A PWAT OF 1.31". FCST SOUNDINGS THIS AFTERNOON CONTINUE TO SHOW VERY STEEP LOW/MID LEVEL LAPSE RATES...WITH SFC DEWPOINTS MIXING OUT INTO THE LOWER/MID 60S. EVEN WITH SFC DEWPOINTS DROPPING FROM THEIR PRESENT VALUES IN THE UPPER 60S TO LOWER 70S INTO THE LOWER/MID 60S...FCST SOUNDINGS ARE SHOWING QUITE A BIT OF AVAILABLE INSTABILITY THIS AFTERNOON WITH TEMPS EXPECTED TO REACH INTO THE UPPER 90S TO NEAR 100F. THE BIG QUESTION TODAY IS WHETHER OR NOT WE WILL HAVE A SUFFICIENT FOCUS FOR SCATTERED CONVECTION TO DEVELOP. AT PRESENT...THE REMNANT MCS OUTFLOW BOUNDARY HEADED THIS WAY IS A GOOD CANDIDATE FOR A LOW LEVEL FOCUS...HOWEVER...THE BOUNDARY MAY MIX OUT/WEAKEN AND SLOW DOWN ONCE IT SPILLS OFF THE MOUNTAINS INTO THE FOOTHILLS AND WESTERN PIEDMONT OF NC...AND IT IS DIFFICULT TO ANTICIPATE HOW MUCH LIFT WILL BE ASSOC/W THIS FEATURE. THE OUTFLOW BOUNDARY IS ALREADY INITIATING CONVECTION IN SOUTH CENTRAL VA. THE WEAK 250MB SHORTWAVE JUST WEST OF THE MOUNTAINS IS ANOTHER CANDIDATE FOR CONVECTIVE SUPPORT...AT THE UPPER LEVELS. HOWEVER...THE LATEST RUC IS NOT SHOWING MUCH IN THE WAY OF LIFT IN ASSOC/W THIS FEATURE OVER CENTRAL NC...KEEPING THE BEST DPVA (ASSOC/W A 15/S VORTMAX) FURTHER SOUTH OVER GA/SC. ANOTHER POTENTIAL SOURCE OF LOW LEVEL LIFT MAY COME FROM THE SEABREEZE...DEPENDING ON HOW FAR INLAND IT PROPAGATES. GIVEN STRONG DIURNAL HEATING...IT SHOULD BE ABLE TO HEAD RELATIVELY FAR INLAND...AS MUCH AS LIGHT SOUTHWEST (COAST PARALLEL) LOW LEVEL WINDS WILL ALLOW. AT THIS TIME WILL SHOW LOW CHANCE (30%) POPS ACROSS THE ENTIRE CWA THIS AFTERNOON DUE TO THE PRESENCE OF STRONG INSTABILITY AND A FEW POSSIBLE SOURCES FOR LIFT...WHICH MAKE IT DIFFICULT TO PINPOINT ONE AREA OVER ANOTHER FOR A `HIGHER` CHANCE. WILL NEED TO WATCH THE SE COASTAL PLAIN...HOWEVER...AS THERE ARE INDICATIONS THAT THE SEABREEZE MAY INDEED PUNCH INLAND FAR ENOUGH TO ENHANCE CHANCES IN THAT AREA. ANY STORMS THAT DO DEVELOP THIS AFTERNOON COULD EASILY BECOME SEVERE GIVEN THE VERY STEEP LOW/MID LEVEL LAPSE RATES...WITH A PRIMARY THREAT OF DAMAGING WINDS IN EXCESS OF 60 MPH. TEMPERATURES: TEMPS THIS AFTERNOON WILL DEPEND ON HOW FAR INTO THE AREA THE REMNANT MCS OUTFLOW BOUNDARY WILL PENETRATE...AND HOW MUCH CLOUD COVER / CONVECTION DEVELOPS ACROSS THE AREA THIS AFTERNOON. CURRENT INDICATIONS ARE THAT AREAS FROM THE TRIANGLE SOUTH/EAST SHOULD HAVE NO PROBLEM MAKING IT INTO THE UPPER 90S TO NEAR 100F THIS AFTERNOON BASED ON THICKNESSES AND MOS GUIDANCE...WHILE THE TRIAD AREA MAY TOP OUT IN THE MID/UPPER 90S...DEPENDING HOW MUCH (IF ANY) AIRMASS MODIFICATION OCCURRED IN ASSOC/W THE OUTFLOW BOUNDARY PASSAGE. ALTHOUGH DEWPOINTS ARE CURRENTLY IN THE UPPER 60S TO LOWER 70S... THEY ARE EXPECTED TO DROP INTO THE LOWER/MID 60S THIS AFTERNOON IN RESPONSE TO STRONG DIURNAL MIXING. IF THIS OCCURS AS EXPECTED... HEAT INDEX VALUES WILL REMAIN AT OR BELOW 104F THIS AFTERNOON. HOWEVER...IF THEY SOMEHOW MANAGE TO STAY IN THE UPPER 60S TO NEAR 70F...THEN HEAT INDEX VALUES COULD EXCEED 105F FOR A FEW HOURS IN SOME LOCATIONS IN THE SANDHILLS...COASTAL PLAIN AND POTENTIALLY THE TRIANGLE AREA AS WELL. IF THIS OCCURRED...WE WOULD TECHNICALLY BE AT HEAT ADVISORY CRITERIA. GIVEN THAT THERE IS TOO MUCH UNCERTAINTY WITH TEMPS/DEWPOINTS THIS AFTERNOON...PREFER TO NOT ISSUE A HEAT ADVISORY...AND WILL MAKE SURE THERE IS ENHANCED WORDING FOR HEAT IN THE HWO. TONIGHT...LOW TEMPERATURES EXPECTED TO BE VERY MILD IN THE LOWER/MID 70S. WILL INTRODUCE A SLIGHT CHANCE OF SHOWERS/STORMS OVERNIGHT TO TAKE INTO ACCOUNT ANY ACTIVITY THAT MAY PERSIST WELL PAST SUNSET AND/OR PROPAGATE INTO CENTRAL NC FROM THE NORTH OR WEST...BASED ON THE LATEST GFS/NAM RUNS WHICH SHOW A POTENTIAL FOR THIS TO OCCUR...WITH FCST SOUNDINGS SHOWING ENOUGH ELEVATED INSTABILITY TO SUPPORT CONVECTION. -VINCENT && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 300 AM TUESDAY... MID AND UPPER LEVEL TROUGHS DROP THROUGH THE OHIO VALLEY LATE TONIGHT AND WEDNESDAY...WITH WEST TO SOUTHWEST MID LEVEL WINDS OVER NORTH CAROLINA INCREASING TO 15 TO 30 KNOTS BY LATE AFTERNOON WEDNESDAY. LIKELY RAIN CHANCES BY WEDNESDAY AFTERNOON WITH HEAVIER RAINFALL AMOUNTS MORE LIKELY NEAR AND NORTH OF HIGHWAY 64. CHANCES FOR SHOWERS OR THUNDERSTORMS WILL CONTINUE INTO WEDNESDAY NIGHT. THE LATEST NAM...ECMWF AND GFS MODEL RUNS HAVE SIGNIFICANTLY ADVANCED THE MID LEVEL TROUGH POSITION THURSDAY MORNING... TO WHERE THURSDAY COULD TURN OUT ENTIRELY DRY. THE CANADIAN AND NAVY NOGAPS CONTINUE SLOWER WITH THIS TROUGH AND LINGER RAIN CHANCES OVER CENTRAL NORTH CAROLINA...AT LEAST IN THE EAST HALF. CONFIDENT ENOUGH TO REMOVE RAIN FROM THE WEST FOR THURSDAY...BUT WILL DELAY DRYING OUT THE EAST UNTIL NEAR SUNSET. IF THE MORNING MODELS CONFIRM THE DRYING TREND...THE EAST MAY END UP BEING DRY THURSDAY AS WELL. CURRENT FORECAST TEMPERATURES ARE ACCEPTED. MORNING LOWS 68 TO 73. AFTERNOON HIGHS 88 TO 93. -RLH && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 410 AM TUESDAY... INITIALLY WEST NORTHWEST FLOW ALOFT FRIDAY THROUGH SATURDAY WILL BACK TO WEST SOUTHWESTERLY IN RESPONSE TO A DEEPENING VORTEX OVER SOUTHERN ONTARIO AND QUEBEC SUNDAY INTO THE FIRST OF NEXT WEEK. THIS SHOULD RESULT IN A BROAD LOW LEVEL WARM MOIST ADVECTION AND MCS BEARING REGIME FROM THE MID MS VALLEY TO THE MID ATLANTIC STATES THROUGH SATURDAY... IN THE CONFLUENT FLOW TO THE WEST OF THE LONGWAVE TROUGH ATTENDANT THE SOUTHERN CANADA VORTEX. THEN AS THE TROUGH ALOFT SHARPENS... ADDED LIFT FROM THE UPPER JET MAY CREEP CLOSE ENOUGH TO ENHANCE PRECIPITATION CHANCES SUNDAY THROUGH MONDAY. THUS...INITIALLY DRY AND SUBSIDENT AIR ON FRIDAY -- IN THE WAKE OF THE TROUGH FROM THE SHORT TERM -- MAY MOISTEN RATHER QUICKLY FROM THE WEST FRIDAY EVENING/NIGHT... AS THE AFOREMENTIONED THETA-E ADVECTION AND LOW AMPLITUDE IMPULSES ALOFT (PERHAPS IN THE FORM OF AN MCV) PROVIDE FOR LARGE SCALE ASCENT OVER OUR REGION. WILL ACCORDINGLY DELAY POPS FOR MOST OF THE DAY FRIDAY WHEN THE SUBSIDENCE INVERSION LINGERS... THEN CARRY A CHANCE POP INTO THE LATE EVENING HOURS TO ACCOUNT FOR THE POSSIBLE ARRIVAL OF MCS RESIDUALS FROM THE TN VALLEY. THIS TREND OF RESIDUAL MCS ACTIVITY OR RENEWED DEEP CONVECTIVE DEVELOPMENT OVER OUR REGION FROM UPSTREAM MCV`S OR DIFFICULT TO TIME LOW AMPLITUDE BAROCLINIC WAVES/SHORTWAVE TROUGHS ALOFT WILL THEN CONTINUE THROUGH THE PERIOD... AS WE REMAIN IN A RELATIVELY MOIST AND CONDITIONALLY UNSTABLE AIR MASS. TEMPERATURES THROUGH THE PERIOD SHOULD RANGE FROM THE UPPER 80S TO LOWER 90S FOR HIGHS AND WITHIN A FEW DEGREES EITHER SIDE OF 70 DEGREES FOR LOWS. -MWS && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... AS OF 720 AM TUESDAY... BRIEF IFR/MVFR CONDITIONS IN SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING... THEN MVFR FOG AND HAZE WEDNESDAY MORNING. A TRICKY FORECAST REGARDING THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING. A LARGE OUTFLOW BOUNDARY AND ASSOCIATED PRONOUNCED RAIN-COOLED MESO-HIGH... GENERATED BY AN OVERNIGHT THUNDERSTORM COMPLEX OVER THE OHIO VALLEY... WAS SITUATED ALONG THE WEST SLOPES OF THE CENTRAL APPALACHIANS AT SUNRISE THIS MORNING. PURE EXTRAPOLATION OF THIS FEATURE HAS IT ON THE DOORSTEP OF THE WESTERN TERMINALS AROUND 15Z... THEN SOUTHEASTWARD TO KFAY BY 18Z. IT IS UNLIKELY THAT SURFACE HEATING WILL HAVE SUFFICIENTLY DESTABILIZED THE ATMOSPHERE BY 15Z... SO ASIDE FROM A BRIEF WIND SHIFT TO NORTHWEST... THE BOUNDARY MAY PASS WITH LITTLE FANFARE AT WESTERN TERMINALS. HOWEVER... IT MAY TRIGGER RENEWED SHOWERS AND THUNDERSTORMS BY THE TIME IT ARRIVES AT KRDU... AND ESPECIALLY KFAY AND KRWI... WHERE TEMPERATURES ARE APT TO BE AROUND 90 DEGREES BY THAT TIME. ADDITIONAL SHOWERS AND THUNDERSTORMS WILL THEN LIKELY DEVELOP TO THE WEST... ALONG THE EAST SLOPES OF APPALACHIANS AND IN THE FOOTHILLS. THESE STORMS COULD PROPAGATE EASTWARD INTO THE KGSO AND KINT VICINITY LATER THIS AFTERNOON OR THIS EVENING. HAVE INCLUDED ONLY A CB CLOUD GROUP IN THE TAFS GIVEN THE STILL SOMEWHAT UNCERTAIN TIMING AND COVERAGE OF CONVECTION. THE MAGNITUDE OF THE FORECAST INSTABILITY COMBINED WITH STEEP LAPSE RATES FROM THE SURFACE TO THE MID LEVELS WILL PROVIDE AMPLE ENERGY FOR STRONG (POTENTIALLY DAMAGING) WIND GUSTS IN ANY STORMS THAT DEVELOP. LOOKING BEYOND TUESDAY EVENING... THE SAME AIR MASS OVERHEAD WILL RESULT IN MVFR HAZE AND FOG AGAIN WEDNESDAY MORNING. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED WEDNESDAY AFTERNOON AND EVENING... AS A COLD FRONT MOVES INTO OUR REGION FROM THE NORTHWEST. LINGERING LOW LEVEL MOISTURE IN THE COASTAL PLAIN MAY ALSO PROMOTE MVFR/IFR FOG DEVELOPMENT AT KRWI AND KFAY EACH MORNING THURSDAY THROUGH SATURDAY. -MWS && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...RLH LONG TERM...MWS AVIATION...MWS nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BISMARCK ND 415 AM CDT TUE JUL 22 2008 .SHORT TERM...TODAY THROUGH THURSDAY NIGHT... SOME OF THE RICHEST BOUNDARY LAYER MOISTURE OF THE SUMMER IS ON OUR DOORSTEP AND SHOULD BE WELL IN PLACE BY LATE WED...WHEN 00Z MODELS ARE QUITE AGREEABLE TO LOCAL MID/UPPER 60S F DEWPOINTS. THIS MAKES FOR AN INCREASING RISK OF THUNDER AND SEVERE POTENTIAL AS AN UPPER RIDGE AXIS PEAKS OVER ND TODAY AND IS REPLACED BY SW FLOW ALOFT AND TWO IF NOT THREE S/W`S...EACH GROWING IN STRENGTH UNTIL THE PRIMARY WAVE PASSES ON THU. THE 00Z MODELS ARE IN AGREEMENT ON THE SYNOPTIC SCALE AND AS A RESULT THE FCST DATABASE IS A MIX OF ALL...THOUGH IT IS WORTH NOTHING THAT THE 00Z GFS IS THE DRIEST SOLUTION 06-18Z WED. THE MODEL ALSO INITIALIZED SFC DEWPOINT FIELDS POORLY AND THIS HAS PROPAGATED UNTIL AT LEAST 06Z...THOUGH ITS MOS PRODUCTS RESOLVE THE SITUATION MORE CLEARLY. AS A RESULT...A BIT MORE WEIGHT WAS PUT INTO THE 00Z NAM SOLUTION WITH THIS RELEASE. FIRST...LOW/MID LVL THETA-E ADVECTION IS DRIVING ELEVATED CONVECTION IN THE FAR SW ATTM. RADAR SIGNATURES SUGGEST ENOUGH STRENGTH TO SUPPORT SOME HAIL. THE 06Z RUC KEEPS THIS ACTIVITY AROUND IN THE SW INTO THE MORNING HOURS. MOIST SE FLOW STRENGTHENS THE NEXT 36 HRS...REFLECTED IN SFC WINDS WHICH GET GUSTY IN THE SW LATE TDY AND CENTRAL WED WHEN MODELS MIX TO NEARLY 800 MB WHERE 30KT WINDS RESIDE. THIS IS IN RESPONSE TO HEIGHT FALLS ASSOCIATED WITH S/W ENERGY TO OUR WEST...WHICH ALSO ORGANIZES A SFC COLD FRONT IN EASTERN MT BY 12Z WED...SHIFTING IT TO NEAR A KISN-KDIK CORRIDOR 21-00Z WED AND SHOVING IT THROUGH KJMS THU MORNING. THIS FEATURE WILL BE THE FOCUS FOR THE HIGHEST-IMPACT WX DURING THE SHORT TERM...BUT TWO OTHER RISKS PRESENT THEMSELVES... 1/POTENTIAL SFC-BASED CONVECTION IN WSTRN ND LATE AFTN/EVE TDY AND 2/ NEWLY-DEVELOPED ELEVATED CONVECTION AND/OR A WEAKENING MCS MOVING INTO THE AREA FROM MT AFT 06Z TONIGHT. WHERE 1/ IS CONCERNED...THE MODELS ARE IN DIFFERENT CAMPS WITH A VORT MAX IN NW WY ATTM...WITH THE 00Z GFS SHOVING IT INTO SW ND BY 00Z WED WHILE THE 00Z NAM TAKES IT ON A MORE NRLY COURSE INTO MT. WE DO BECOME UNSTABLE WITH SBCAPE OF 600 J/KG IN THE FAR SW LATE TDY...BUT THE DEEPER BUOYANCY IS FURTHER WEST IN MT. THAT SAID...IF MOISTURE DOES NOT MIX OUT MUCH THEN SBCAPE WILL BE HIGHER. THE MAIN PROBLEM IS WITH THE MOVEMENT OF THE VORT...A GFS SOLUTION PORTENDING SCT TSRA BY 00Z AND THE NAM KEEPING IT DRY. ENOUGH UNCERTAINTY TO KEEP SLGT CHANCE POPS IN THE DATABASE. NUMBER 2/ HAS GREATER CERTAINTY AS A 40-45KT LLJ AND NOTABLE 850 THETA-E ADVECTION DRIVE ELEVATED CONVECTION AFT 06Z TONIGHT. LENGTHENING MOISTURE TRANSPORT VECTORS AND PWATS TO 1.5 INCHES SUPPORT DEEP MOIST CONVECTION...AND A RESERVOIR OF MODERATE INSTABILITY /MUCAPE OF 1000-1500 J/KG/ IS AVAILABLE TO ELEVATED PARCELS. THUS THERE IS SVR POTENTIAL...ESPECIALLY 09-15Z WED OVER CENTRAL ND...WHICH IS TYPICALLY THE MOST ACTIVE TIME FOR ELEVATED HAILERS ON THE LLJ. THE 00Z NAM CLEARLY DEPICTS THIS SCENARIO IN ITS QPF FIELDS. THE THREAT OF AN MCS MOVING INTO THE AREA FROM MT IS ALSO NON-ZERO...AND IT COULD BE THAT THE EVENTUAL CONVECTION IS SOME COMBINATION OF BOTH NEW DEVELOPMENT AND ANY PRE-EXISTING MCS. THE BIGGER STORY WILL BE INITIATION OF SFC-BASED STORMS ALONG THE COLD FRONT LATE WED AFTN. STEEP MID LVL LAPSE RATES AND STRONG DIABATIC HEATING WILL PUSH MLCAPE VALUES TO 2500+ J/KG. MODERATE MID LVL FLOW WILL CONTRIBUTE TO 30-40KTS OF 0-6KM BULK SHEAR... SUFFICIENT FOR ORGANIZED UPDRAFTS AND EVEN SUPERCELLS GIVEN THE INSTABILITY. MODELS SUGGEST ENOUGH LOW LVL CONVERGENCE TO ERODE CAPPING ALONG THE FRONT SO CONFIDENCE ON AN ORGANIZED SVR EVENT IS INCREASING. MODELS ALSO SUGGEST THAT THE LLJ WED NIGHT IS FOCUSED OVER SD/NE AND THAT THE UPPER JET IS NOT PARTICULARLY INTERESTING... SO IT IS NOT YET CLEAR HOW LONG-LIVED OUR EVENT WILL BE. WAVE NUMBER THREE FINALLY SHIFTS OVER THE NRN PLAINS ON THU. THE MAIN FRONTAL ZONE WILL HAVE PASSED THRU THE FA WED NIGHT...WHICH MAKES THE CONVECTIVE SCENARIO MORE DIFFICULT DURING THIS PERIOD. 00Z SFC WIND FIELDS SUGGEST LITTLE RESPONSE TO THE HEIGHT FALLS ALOFT... SOMETHING THAT MAY NOT BE ENTIRELY TRUE. WE COULD WIND UP WITH SOME NEW /ALBEIT WEAK/ CONVERGENCE ZONES OVER THE AREA THU AFTN. IF THIS IS THE CASE THE THUNDER THREAT WOULD BE ENHANCED. REGARDLESS...WE REMAIN UNSTABLE AND HENCE WE HAVE ADDED SLGT CHANCE POPS TO THE FCST DATABASE IN THIS PERIOD. .LONG TERM...FRIDAY THROUGH MONDAY NIGHT... FOR THE MOST PART...FOLLOWED A SOLUTION CLOSE TO THE 00 UTC GFS AND BLENDED WITH THE 00 UTC ECMWF WHEN APPROPRIATE IN GRIDS THIS MORNING. MODELS/ENSEMBLES ARE IN GOOD AGREEMENT WITH THE SOMEWHAT AMPLIFIED POSITIVE PACIFIC NORTH AMERICAN LONGWAVE PATTERN OVER NORTH AMERICA THIS PERIOD. THERE ARE TWO MAIN SHORTWAVES FORECAST TO PASS OVER NORTH DAKOTA. THE FIRST...LINGERING MIDDLE LEVEL ENERGY FROM THURSDAYS SYSTEM SHOULD COOL MIDDLE LEVEL TEMPERATURES AND PROVIDE SUFFICIENT SYNOPTIC SCALE LIFT TO INITIATE AT LEAST SCATTERED CONVECTION. THE SECOND...AN ELONGATED MIDDLE/UPPER LEVEL TROUGH EXTENDING FROM THE NORTHWEST TERRITORIES OF CANADA ALL THE WAY SOUTH INTO THE NORTHERN PLAINS. AGAIN...ASSOCIATED DESTABILIZATION OF THERMAL PROFILES AND DEEP-LAYER ASCENT SUPPORTS MCS FORMATION ON SUNDAY/MONDAY. OF COURSE...TIMING LOW-PREDICTABILITY IMPULSES IS VERY DIFFICULT IN THE EXTENDED PERIOD...AND THEY MAY EJECT OUT AHEAD OF THE MAIN TROUGH AXIS. EXPECT TIMING ISSUES TO RESOLVE THEMSELVES AS THE WEEKEND APPROACHES. OTHERWISE...TEMPERATURES SHOULD REMAIN NEAR OR SLIGHTLY ABOVE CLIMATOLOGY AS THE LONGWAVE RIDGE SITS ALONG THE FRONT RANGE. && .AVIATION... SURFACE HIGH PRESSURE OVER SOUTHERN MANITOBA IS FORECAST TO CONTINUE MOVING EASTWARD AS BROAD LOW PRESSURE OVER THE NORTHERN ROCKIES/HIGH PLAINS DEEPENS AND APPROACHES EASTERN MONTANA/WESTERN NORTH DAKOTA BY WEDNESDAY EVENING. EXPECT VFR CONDITIONS WITH LOW-LEVEL SOUTHEASTERLY WINDS. SOME THUNDERSTORMS ARE EXPECTED TO FORM AHEAD OF THIS LOW PRESSURE...BUT IT APPEARS THAT MOST OF THE ACTIVITY WILL REMAIN WEST OF THE STATE UNTIL AFTER DARK ON TUESDAY NIGHT. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ CJS/NH/SCHECK nd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GRAND FORKS ND 1006 AM CDT MON JUL 21 2008 .DISCUSSION...FORECAST FOR TODAY ON TRACK AND EXPECT NO CHANGES TO ONGOING FORECAST. MAIN CHALLENGE WILL CONTINUE TO BE TEMPERATURES AND ISOLD THUNDER CHANCES. 12Z NAM/RUC CONVECTIVE TEMPS THIS AFTERNOON ARE NEAR THE EXPECTED MAX T...SO CURRENT TEMP FORECAST IN GOOD SHAPE. WATER VAPOR IMAGERY SHOWS TWO DISTINCT SHORTWAVES...ONE PROPAGATING THROUGH THE FA NOW...AND ANOTHER NORTH OF INL/BDE PROPAGATING DUE SOUTH. LIFT FROM THE FIRST SHORTWAVE HAS PRODUCED A COUPLE VERY WEAK SHOWERS THIS MORNING EAST OF THE VALLEY. HOWEVER...THESE HAVE DISSIPATED AND EXPECT A BRIEF QUIET PERIOD. LIFT FROM SECOND SHORTWAVE WILL AFFECT MAINLY THE EXTREME NE FA LATE MORNING/AFTERNOON. CURRENT POPS HANDLE THIS WELL. && .AVIATION...VFR CONDITIONS EXPECTED...WITH SOME SCATTERED TO BROKEN CUMULUS THIS AFTERNOON FROM 4-6KFT. KBJI HAS THE BEST CHANCE AT AN ISOLATED TSTORM...BUT WILL LEAVE DRY WITH MINIMAL COVERAGE EXPECTED. && .PREV DISCUSSION... /ISSUED 351 AM CDT MON JUL 21 2008/ SHORT TERM... THE MAIN CHALLENGE WILL BE TEMPS AND CONVECTIVE CHANCES. MODELS ARE IN GOOD AGREEMENT OVERALL...WITH THE GFS HANDLING CURRENT SHORTWAVE BETTER SO WILL UTILIZE. A WEAKENING CONVECTIVE CLUSTER CONTINUES TO BRUSH THE FAR SOUTH. THUNDER HAS DISSIPATED IN OUR AREA...WITH THE MAIN INSTABILITY AND MOISTURE IN SD INTO IA. FOR TODAY...CYCLONIC FLOW WILL LINGER IN THE FAR NE WITH MUCAPES TO AROUND 1000 J/KG THIS AFTERNOON. WE WILL CONTINUE A LOW POP FOR THUNDER HERE. ELSEWHERE...LACK OF FORCING AND WEAKER INSTABILITY SHOULD PRECLUDE ANY THUNDER. A FEW LINGER SHOWERS COULD BE POSSIBLE IN THE FAR SOUTH THIS MORNING...BUT ACTIVITY SHOULD BE OUT OF THE REGION AFTER 12Z. TEMPS WILL BE A FEW DEGREES WARMER THAN YESTERDAY WITH A BIT MORE SUN AND SLIGHTLY WARMER 925MB TEMPS. ON TUE...A SHORTWAVE RIDGE WILL BUILD OVER THE REGION AND PROVIDE DEEP LAYERED SUBSIDENCE AND DRYING. PLENTIFUL SUNSHINE SHOULD HELP BOOST TEMPS SLIGHTLY ABOVE NORMAL. RETURN FLOW SHOULD DEVELOP ALONG AND WEST OF THE VALLEY BY AFTERNOON. WED-THU...A SHORTWAVE WILL TOP THE RIDGE AND BRING THE THREAT FOR THUNDERSTORMS INTO THE REGION. MOISTURE PROFILES INCREASE BY WED AFTERNOON...AND PWATS CLIMB TO NEAR 1.5 INCHES BY WED NIGHT. INSTABILITY FIELDS ARE NOT THAT IMPRESSIVE...BUT STRONG FORCING AND A LOW LEVEL JET WITH MOISTURE TRANSPORT WILL MEAN SHOWERS AND STORMS BY WED EVENING THROUGH MUCH OF THU. TEMPS MAY BE AFFECTED BY CLOUDS AND CONVECTIVE DEBRIS...AND SOME AREAS MAY BE COOLER FROM LACK OF INSOLATION. AREAS THAT RECEIVE SUNSHINE MAY WARM ABOVE NORMAL THOUGH. BY FRIDAY...THERE MAY BE ANOTHER SHORTWAVE AND COLD FRONT THAT SWEEP THROUGH THE REGION. FOR NOW WILL KEEP IT DRY...BUT THE GFS IS QUITE BULLISH WITH A THREAT FOR CONVECTION. WE MAY NEED TO ADD POPS EVENTUALLY...AND WILL MENTION TO DAY SHIFT. LONG TERM... SAT/SUN SHOULD BE DRY WITH TEMPS NEAR TO SLIGHTLY BELOW NORMAL. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ TG nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 1001 PM EDT MON JUL 21 2008 .SYNOPSIS... WEAK LOW PRESSURE SYSTEMS TRAVELING ALONG A SLOW MOVING COLD FRONT WILL TRIGGER SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS THROUGH TOMORROW NIGHT. THE FRONT WILL MOVE SOUTH OF THE REGION BY WEDNESDAY MORNING. THEN HIGH PRESSURE WILL BUILD IN WITH DRIER WEATHER FOR THE LATTER PART OF THE WEEK. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... NOW THAT MCS HAS TAKEN SHAPE BACK ACROSS ILLINOIS...HAVE BUMPED UP POPS ACROSS THE SOUTHWEST HALF OF OUR CWA...AS IT SHOULD CONTINUE TO DROP SOUTHEAST TOWARD OUR AREA OVERNIGHT. WILL ALSO INCLUDE SEVERE WORDING ACROSS THE SOUTHWEST...WITH DAMAGING WINDS BEING THE PRIMARY THREAT. ------------------------------------------------------------------- SCATTERED THUNDERSTORM ACTIVITY IS REMAINING TO OUR EAST AND SKIES ARE MAINLY CLEAR ACROSS THE AREA ATTM. STILL THINK THERE IS A POSSIBILITY OF SOME REDEVELOPMENT LATE TONIGHT AS SHORT WAVE ENERGY OVER IOWA AND NORTHERN ILLINOIS WORKS ITS WAY EAST. THE LATEST RUC IS HINTING AT A BIT OF AN INCREASING LOW LEVEL JET AND THIS WOULD ENHANCE THE FORCING. AS A RESULT...WILL ALLOW FOR A CHANCE OF THUNDERSTORMS LATE TONIGHT...ESPECIALLY ACROSS THE SOUTHWEST...WHERE INSTABILITY AND FORCING SHOULD BE THE BEST. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/... WHAT TAKES PLACE TONIGHT WILL HAVE AN IMPACT ON EVENTS FOR TUES AS DIFFUSE FRNTL BNDRY SAGS SLOWLY SOUTH THRU OH VLY AND PERSISTENT UPR LO SPIRALS OVER THE GRT LKS. MODEL CONSENSUS FAVORING THE OP GFS SOLN FROM SUNDAY WHICH WAS HOLDING BACK PASSAGE OF THE MAIN UPR TROF AXIS UNTIL ERLY WED. PRESENCE OF AFOREMENTIONED MID MISSISSIPPI VLY MCS AND ITS EFFECTS ON REGION IN THE MORNING WILL DETERMINE LEVEL OF INSTABILITY PRESENT FOR AFTN CONVECTION. WILL MAINTAIN CHC POPS THRU THE DAY TUES WITH FOCUS OF HIGHEST POPS ACRS SRN 1/2 FCST AREA INVOF FRNTL BNDRY AND WHERE MOST UNSTABLE ATMOSPHERE SHOULD BE LOCATED. IF ATMOSPHERE CAN BECOME MODERATELY UNSTABLE...THE THREAT FOR SVR TSTMS WILL EXIST ONCE AGAIN... PARTICULARLY DURING AFTN HOURS AS ANOTHER S/WV PROGGED TO PASS THRU REGION. 90KT UPR JET ROTATING AROUND BASE OF UPR TROF WILL ACCENTUATE UPR DIFFLUENCE OVER FCST AREA AS WELL. FRONT WILL SAG SOUTH OF REGION TUES NIGHT AS UPR TROF AXIS SWINGS IN. WILL CONTINUE TREND OF DECREASING POPS FROM NORTH TO SOUTH THRU THE NIGHT AS SFC HI PRES BUILDS IN FROM THE LWR GRT LKS. SLUGGISH SOUTHWARD MOVEMENT TO FRNTL BNDRY MAY KEEP PCPN LINGERING ACRS FAR SRN FCST AREA ALL NIGHT. UPR TROF AXIS WILL SHIFT EAST OF THE REGION WED WITH SFC HI PRES BRINGING COOLER/DRIER WX INTO THE OH VLY THRU THE REMAINDER OF THE SHORT TERM. TEMPS...FWC GUID PROVIDED A NICE MIDDLE OF THE ROAD SOLN (FROM WARMER MAV/COOLER MET) FOR TEMPS TUES/TUES NIGHT AND TRENDED TOWARDS ITS NUMBERS. MAV GUID LOOKED REASONABLE FOR WED AND WED NIGHT AS TEMPS FALL SLIGHTLY BELOW NORM. && .LONG TERM /THURSDAY THROUGH MONDAY/... HAVE TAKEN A BLEND OF THE OPERATIONAL ECMWF AND GFS ENSEMBLE MEAN...WHICH IS IN LINE WITH THE HPC FORECAST. FOR THURSDAY INTO THURSDAY NIGHT...PESKY UPPER LEVEL TROF WILL PIVOT NORTHWARD INTO NRN QUEBEC. THIS WILL ALLOW SFC HIGH PRESSURE TO BUILD INTO THE REGION ON THURSDAY...MOVING EAST OF THE FORECAST AREA THURSDAY NIGHT. FOR FRIDAY THROUGH SATURDAY...IT APPEARS THAT A WEAK COLD FRONT WILL NOW MOVE THROUGH THE GREAT LAKES/LOWER OHIO VALLEY REGION FRIDAY NIGHT INTO SATURDAY MORNING. HENCE...I HAVE REMOVED POPS FOR FRIDAY DURING THE DAY. AGAIN...WITH THE FRONT BEING WEAK...HAVE KEPT LOW CHC POPS LATE FRIDAY NIGHT INTO SATURDAY ATTM. FOR SUNDAY INTO MONDAY...MODELS INDICATE THAT AN UPPER LEVEL TROF MAY REESTABLISH ITSELF ACROSS SE CANADA...NRN NEW ENGLAND AND THE EASTERN GREAT LAKES. ATTM...IT APPEARS OUR AREA WILL BE ON THE BACK SIDE OF THIS SYSTEM WILL A SFC RIDGE OF HIGH PRESSURE IN PLACE. WILL CONTINUE WITH A DRY FORECAST. AS FOR TEMPERATURES...THEY WILL AVERAGE SLIGHTLY BELOW NORMAL THURSDAY INTO THURSDAY NIGHT. THEREAFTER...THEY WILL AVERAGE NEAR NORMAL FRIDAY AND SATURDAY...RETURNING TO SLIGHTLY BELOW NORMAL VALUES BY EARLY NEXT WEEK. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... SEVERAL BOUNDARIES EVIDENT ACROSS THE REGION ON BOTH THE RADAR AND VISIBLE SATELLITE IMAGES EARLY THIS EVENING. IN THE PAST HOUR...SOME THUNDERSTORM ACTIVITY HAS FIRED ALONG ONE OF THESE BOUNDARIES JUST EAST OF THE COLUMBUS AREA. THIS ACTIVITY HAS BEEN TRAINING EAST ALONG THE BOUNDARY...BUT REDEVELOPMENT APPEARS TO BE REMAINING TO THE EAST OF THE KCMH AND KLCK TAF SITES. AS A RESULT...WILL PLAN ON KEEPING BOTH OF THOSE SITES DRY TO START OFF WITH AT VALID TIME. MEANWHILE...WHAT APPEARS TO BE A MORE PROMINENT BOUNDARY CURRENTLY EXTENDS FROM CENTRAL INDIANA DOWN INTO FAR SOUTHEAST OHIO. THIS BOUNDARY APPEARS TO BE SAGGING SLOWLY SOUTH...AND THE LATEST RUC IS HANGING ON TO SOME DECENT ELEVATED INSTABILITIES...PARTICULARLY TO THE SOUTH OF THIS BOUNDARY OVERNIGHT. AS A RESULT...THINK CONVECTION ASSOCIATED WITH SHORT WAVE CURRENTLY OVER IOWA...WILL LIKELY TRACK SOUTHEAST ALONG THIS BOUNDARY AND INTO OUR AREA LATER TONIGHT...AND THIS MAY BE AIDED SOMEWHAT BY A BIT OF AN INCREASING 925-850 MB JET LATE TONIGHT. THINK BEST CHANCE FOR CONVECTION WILL BE ACROSS OUR SOUTH SO WILL ALLOW FOR A TEMPO GROUP FOR TSTMS LATE TONIGHT INTO EARLY TUESDAY MORNING FOR KCVG AND KLUK...AND THEN JUST A VCTS FOR KILN/KDAY...AND THEN KEEP KCMH AND KLCK DRY. IN THE WAKE OF THIS CONVECTION...EXPECT TO SEE A LULL IN PCPN THROUGH THE REST OF THE MORNING HOURS. HOWEVER..AIRMASS SHOULD THEN DESTABILIZE AGAIN THROUGH THE DAY. THIS WILL LIKELY LEAD TO SOME SCATTERED THUNDERSTORM DEVELOPMENT ONCE AGAIN. THINK BEST CHANCE WILL AGAIN BE ACROSS THE SOUTH WHERE INSTABILITIES ARE PROGGED TO BE THE HIGHEST AND BETTER CHANCE EXIST FOR FORCING ALONG LEFTOVER BOUNDARY. OUTLOOK...TSTMS POSSIBLE SATURDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...RYAN NEAR TERM...JGL SHORT TERM...RYAN LONG TERM...HICKMAN AVIATION...JGL oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 315 PM EDT MON JUL 21 2008 .SYNOPSIS... DISTURBANCES RUNNING THROUGH UPPER LEVEL FLOW WILL CAUSE A CHANCE OF THUNDERSTORMS TONIGHT. COLD FRONT APPROACHES TUESDAY...WITH A WAVE MOVING ALONG IT WEDNESDAY. HIGH PRESSURE BUILDS THURSDAY. && .NEAR TERM /THROUGH TUESDAY/... DIFFICULT FORECAST TONIGHT...IN TRYING TO DETERMINE WHEN WHERE AND IF CONVECTION WILL FIRE. A BOUNDARY FROM AN OLD COMPLEX WELL UPSTREAM...SWEPT SOUTHEAST AND DISSOLVED INTO THE AREA TO PROVIDE A BIT OF A STABILIZING EFFECT WHILE VEERING SURFACE WINDS TO NORTHWEST AND ELIMINATING SURFACE CONVERGENCE. A SECOND COMPLEX DEVELOPED BUT THEN PARTED AROUND THE OLD STABLE POOL OF THE FIRST ONE...WITH ONGOING STORMS NOW WELL NORTH IN NORTHERN OHIO...AND WELL SOUTHWEST OF US IN CENTRAL KENTUCKY /AND THOSE ARE PRESSING SOUTHEAST AND WILL MISS THE CWA/. SO WE HAVE BEEN IN A VOID WITH LACK OF CONVECTIVE ACTIVITY IN BETWEEN. HOWEVER...LOCAL HIGH RESOLUTION MODELS...AS WELL AS THE RUC...STILL SUGGEST NEW ACTIVITY SLIDING SOUTHWARD OUT OF THE CONVECTION TO OUR NORTH. HINTS OF THE START OF THIS ACTIVITY CAN BE SEEN UPSTREAM IN INDIANA. THAT BEING SAID...THE MODELS NEVER REALLY CAPTURED THE INTENSE CONVECTION IN CENTRAL KENTUCKY. THE END RESULT IS AN IFFY CHANCE FORECAST IN WHICH I WOULD HAVE LIKED TO HAVE BEEN MORE DETERMINISTIC. ANY ACTIVITY THAT DOES DEVELOP COULD HAVE STRONG GUSTS WITH IT...CONSIDERING THE SHEAR /ESPECIALLY WEST/. THE FRONT SETTLES MIDWAY THROUGH THE AREA OVERNIGHT...AND THEN SLOWLY DRIFTS NORTHWARD TUESDAY OUT OF AHEAD OF INCOMING FINAL WAVE OF LOW PRESSURE. I PLACED HIGH CHANCE TO LIKELY POPS ALONG THE FRONT...AS THIS TIME WE WILL HAVE MUCH MORE OF A SURFACE FOCUS COMPARED TO TODAY...WHILE STILL HAVING THE MOISTURE AND INSTABILITY. GIVEN CURRENT DEWPOINTS IN MID 60S EAST TO LOW 70S WEST...I PREFERRED THE WARMER MET GUIDANCE FOR LOW TEMPERATURES TONIGHT. HIGHS TUESDAY ARE A BLEND OF MET AND MAV. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... THERE IS STRONG MODEL CONSENSUS OF AN UNUSUALLY STRONG UPPER TROUGH DEVELOPING OVER EASTERN CANADA INTO THE NORTHEASTERN U.S. THIS PERIOD. THIS WILL NOT ONLY KEEP ANY HEAT WAVES AWAY FROM OUR AREA...BUT WILL KEEP MAX TEMPERATURES NEAR NORMAL FOR THIS TIME OF YEAR...MAINLY IN THE 80S. THERE IS EVEN STRONG MODEL AGREEMENT ON A FAIRLY STRONG COOL FRONT DRIVING SOUTHEAST ACROSS OUR AREA WEDNESDAY WITH THE A NORTHERN STREAM SHORT WAVE TO CARVE OUT THIS UPPER TROUGH. PRIOR TO THIS FRONT ARRIVAL WEDNESDAY...SCATTERED SHOWERS AND THUNDERSTORMS WILL INCREASE TUESDAY NIGHT INTO WEDNESDAY MORNING AS SOUTHERLY FLOW TRANSPORTS MOIST AND UNSTABLE AIR NORTHWARD AHEAD OF THE FRONT. MOST OF THE ACTIVITY WILL SHIFT INTO THE MOUNTAINS WEDNESDAY AFTERNOON AS THE FRONT PROGRESSES. HAVE GONE WITH HIGH CHANCE POPS IN THE WEST TO LIKELY POPS IN THE EAST WITH THIS SYSTEM. BY WEDNESDAY EVENING...MOST OF THE ACTIVITY WILL BE IN THE MOUNTAINS AS THE FRONT EXITS TO THE EAST. HIGH PRESSURE WILL BUILD IN RAPIDLY BEHIND THE FRONT WEDNESDAY NIGHT...WITH COOLER AND DRIER AIR BY THURSDAY MORNING. && .LONG TERM /THURSDAY THROUGH MONDAY/... MODELS AGREE THE MEAN UPPER TROUGH OVER THE NORTHEASTERN U.S. WILL BE MAINTAINED THIS PERIOD. THERE IS ALSO MODEL AGREEMENT ON A REINFORCING SHOT OF COOLER AIR ARRIVING IN THE FORM OF ANOTHER COOL FRONT SATURDAY INTO SATURDAY NIGHT. SURFACE HIGH PRESSURE THURSDAY INTO MUCH OF FRIDAY WILL KEEP THINGS ON THE DRY AND LESS HUMID SIDE...WITH NEAR NORMAL MAX TEMPS IN THE 80S. BY FRIDAY NIGHT...RETURN SOUTHERLY FLOW AHEAD OF THE APPROACHING FRONT WILL BRING MOISTURE AND INSTABILITY NORTHWARD AGAIN...LEADING TO SCATTERED SHOWERS AND THUNDERSTORMS FRIDAY NIGHT. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED SATURDAY ALONG AND AHEAD OF THE COOL FRONT...DIMINISHING SATURDAY NIGHT AS THE FRONT EXITS. HOWEVER...BEHIND THIS SYSTEM MUCH COOL AIR ALOFT WILL MOVE IN...AND ENOUGH LINGERING MOISTURE WILL ALLOW FOR ISOLATED TO SCATTERED MAINLY DIURNAL CONVECTION SUNDAY AREAWIDE...CONTINUING IN THE MOUNTAINS MONDAY. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... UPPER LEVEL FEATURE CAUSING THUNDERSTORMS IN CENTRAL KY...WHILE THE SAME FEATURE RUNNING ALONG COLD FRONT IS HELPING OTHER THUNDERSTORMS TO DEVELOP IN CENTRAL TO NORTHERN OH. EXPECTING AT LEAST SOME DEVELOPMENT FOR OUR AREA IN BETWEEN THESE TWO AREAS FOR THIS AFTERNOON AND EVENING...BECAUSE OF COMPLEX OUTFLOW BOUNDARIES FROM CURRENT AND EARLIER CONVECTION. TERMINALS WILL SPEND MOST OF THE TIME AT VFR...BUT ANY CELL PASSING DIRECTLY OVERHEAD COULD CREATE BRIEF MVFR TO IFR CONDITIONS AS WELL AS GUSTY WINDS. MOIST ENVIRONMENT OVERNIGHT SHOULD ALLOW MVFR VIS FOR ALL TERMINALS...WITH PERHAPS IFR FOR KCRW AND ESPECIALLY KEKN...DESPITE INCREASED CLOUD COVER. ALSO...WITH FRONT SAGGING SOUTH INTO AREA...STILL AT LEAST A CHANCE OF SHOWERS AND THUNDERSTORMS EVEN INTO TUESDAY MORNING. AVIATION OUTLOOK /AFTER 18Z TUESDAY/... BRIEF IFR POSSIBLE IN THUNDERSTORMS TUESDAY AND WEDNESDAY. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...MDP/JMV NEAR TERM...MDP SHORT TERM...JMV LONG TERM...JMV AVIATION...MDP oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 307 AM EDT TUE JUL 22 2008 .SYNOPSIS... A SLOW MOVING FRONTAL BOUNDARY OVER THE GREAT LAKES WILL SAG SOUTHWARD INTO PENNSYLVANIA TONIGHT...THEN STALL OUT ACROSS THE SOUTHEAST PART OF THE STATE THROUGH MIDWEEK. HIGH PRESSURE WILL BUILD INTO THE REGION LATE IN THE WEEK...FOLLOWED BY A POSSIBLE COLD FRONT BY NEXT WEEKEND. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... IMPRESSIVE BOW ECHO NOW EXITING SRN SOMERSET/BEDFORD CNTYS ATTM. PIT BASE V SIGNATURES WERE IN EXCESS OF 50KTS AT 3-6KFT AGL. RUC ANAL ALONG WITH IR SAT IMAGERY SHOWS THE MCV HAS NOW MOVED INTO WCENT PA...WITH SCT SHRA/TSRA EVIDENT ON RADAR FM THE MID SUSQ VLY NWWD BACK INTO THE NW MTNS. BROADBRUSHED SCHC/CHC POPS AFT 06Z WITH SOME PATCHY FOG TO DEVELOP TWD DAWN. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/... THE SHOWERS SHOULD TAPER OFF EARLY IN THE WEST. THE HIGH AMBIENT MOISTURE AND PARTIAL CLEARING SHOULD LEAD TO SOME FOG AND PERHAPS STRATUS AGAIN IN THE MORNING. HAVE MADE CLOUD COVER RATHER DARK/DISMAL IN THE WEST LATE TONIGHT. ANY SHOWERS THAT LAST AFTER MIDNIGHT SHOULD BE OVER THE EAST AND EXITING STAGE RIGHT. SOME FOG POSSIBLE THERE...TOO...BUT MOST LIKELY IN THE WEST/CENTRAL. MINS WILL BE MILD/MUGGY AGAIN. LOOK FOR A SIMILAR DAY TO THE PAST WEEK OR SO WITH HOT TEMPS IN THE SE AND COOLER/NEARER-NORMAL TEMPS IN THE NW. FOCUSING MECHANISMS FOR AFTN CONVECTION STILL IN DOUBT AT THIS POINT...BUT THOSE DEAD MCS/S AND THEIR ASSOCIATED VERTICAL MOTION ARE THE BIG SUSPECTS AT THIS TIME. WILL KEEP POPS IN THE SCT/CHC RANGE FOR NOW...AND MAKE IT MOSTLY IN THE AFTN. LATEST SREF DATA SUGGEST HIGHEST CHC OF RAIN TUES NIGHT WILL BE IN THE WEST - ESP THE SW...AS MODELS WANT TO DROP AN MCS RIGHT THRU SWRN PA OVERNIGHT. FELT A GOOD MOVE WAS TO BUMP POPS INTO LIKELY CATEGORY FOR THE SW...AND KEEP CHCS FOR THE REST AT THIS RANGE. TIMING AND UPSTREAM DEVELOPMENT...OR LACK THEREOF...WILL TELL THIS TALE. KEPT MINS VERY MILD/MUGGY AGAIN. IT IS...AFTER ALL...THE HEIGHT OF SUMMER - WITH THE HOTTEST TEMPS /CLIMATOLOGICALLY/ UPON US FOR ALL OF THE NEXT WEEK. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... YESTERDAY I HELD ONTO THE MENTION OF SHOWERS AND STORMS INTO TUESDAY NIGHT...AND EVEN PUT A CHC INTO THE SE FOR WED AM. YESTERDAY THE GFS SHOWED THE UPPER LEVEL TROUGH SHARPENING UP FOR MID WEEK...BUT I DID NOT WANT TO MAKE THE WHOLE WEEK WET. WITH THIS TREND STILL TODAY...LEFT MEINTON OF SHOWERS AND STORMS IN FOR WED...THAT MID SHIFT ADDED...AND ADDED CHC FOR WED NIGHT. GFS SLIGHTLY LESS GLOOMY AND FASTER THAN NAM WITH SYSTEM WED...BUT COULD STILL SEE A SIGNIFICANT SEVERE WEATHER...EVEN HEAVY RAIN EVENT...WITH SUCH A STRONG UPPER LEVEL FEATURE FOR LATE JULY. ONLY HAVE ISSUED ONE FLASH FLOOD WARNING THIS SEASON...AND THAT WAS THE OTHER EVENING WHEN I WAS WORKING. THIS HAS BEEN A WET SUMMER SO FAR...JUST HAVE NOT HAD THE TYPICAL PATTERN FOR HEAVY RAIN SO FAR THIS SEASON. IF ONE IS LOOKING FOR DRY WEATHER...IT LOOKS LIKE THU AND PERHAPS FRIDAY WILL BE THE DAYS. THE OLD FRONT STALLS JUST OFFSHORE AT BEST...AND STARTS TO WORK BACK TO THE NW BY LATE IN THE WEEK. AT THE SAME TIME...A NEW COLD FRONT WORKS EASTWARD ON SAT. WENT WITH DRY WEATHER AGAIN FOR THE PERIOD SUNDAY INTO TUE. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... IR IMAGERGY INDICATES BREAKS IN THE CLOUDS SLIDING IN BEHIND EVENING CONVECTION. FOG/LOW CLOUDS DEVELOPING EVERWHERE BY 08Z AND PERSISTING THRU SUNRISE. UPPER LEVEL LOW CONTINUES TO PUSH EAST INTO WEDNESDAY AS MID-LVL TROUGH DIGS DEEP INTO THE ATLANTIC SEABOARD. EACH OF THE NEXT SEVERAL DAYS WILL PRESENT LOW CHC FOR SHRA/TSRA...ALTHOUGH IT DOES NOT APPEAR THESE WILL BE LONG LIVED CONVECTIVE PIECES. BY SATURDAY YET ANOTHER TROUGH LOOKS TO MOVE IN BRINGING WITH IT MORE SHOWERS AND THUNDERSTORMS FOR THE WEEKEND. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DANGELO/FITZGERALD NEAR TERM...STEINBUGL SHORT TERM...DANGELO LONG TERM...MARTIN AVIATION...BEACHLER/RXR pa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 237 PM EDT TUE JUL 22 2008 .SYNOPSIS... A WEAK COLD FRONT WILL CONTINUE TO MOVE TOWARD AND ACROSS THE FORECAST AREA THROUGH LATE WEDNESDAY. THIS SYSTEM SHOULD STALL ACROSS THE CAROLINAS FOR THE LATTER PART OF THE WEEK...WHILE WEAK HIGH PRESSURE TRIES TO BUILD IN FROM THE NORTH. A REINFORCING COLD FRONT WILL APPROACH FROM THE NORTHWEST AND MOVE OVER THE AREA EARLY NEXT WEEK. && .NEAR TERM /THROUGH WEDNESDAY/... FOR THE REMAINDER OF THIS AFTERNOON AND EVENING...THE FOCUS IS ON WHERE CONVECTION WILL DEVELOP. RUC AND NAM ARE TARGETING THE MOUNTAINS...NE GA AND THE WESTERN UPSTATE WITH BEST CHANCES FOR CONVECTION. CURRENT LAPS CAPE AND REGIONAL RADARS SUPPORTS THIS IDEA. ALSO...CONVECTION CURRENTLY DEVELOPING WITHIN THE SPC WATCH OVER TN WILL MAKE A RUN AT THE NC MOUNTAINS..SO WILL HAVE SOLID/HIGH CHANCE POPS FOR SCATTERED THUNDERSTORMS IN THOSE AREAS...TRENDING LOWER ACROSS THE SOUTHERN UPSTATE. WITH CAPES IN THE 1000-2000J RANGE AND DCAPES AROUND 1000J SEVERE DOWNBURSTS ARE AGAIN A POSSIBILITY. 50-55DBZ CORES AROUND 28K FT SHOULD BE SUFFICIENT FOR SVR WIND AND AROUND 33K FR FOR SVR HAIL. STORMS SHOULD DISSIPATE BY MIDNIGHT AND THEN REMAIN QUIET OVERNIGHT. USED A MOS BLEND FOR MIN TEMPS. WILL ALSO GO AHEAD AN CANCEL THE HEAT ADVISORY FOR THE REMAINDER OF THIS AFTERNOON AS HEAT INDEX COMING UP SHY OF THE NEEDED 105 CRITERIA. ON THU...AN APPROACHING COLD FRONT IS EXPECTED TO TRIGGER FAIRLY WIDESPREAD COVERAGE OF THUNDERSTORMS. UPPER DYNAMICS NOT BAD EITHER AS EAST COAST UPPER TROUGH DEEPENS ALLOWING FOR SOME DECENT LAPSE RATES AND PVA. GFS/NAM DIFFER ON TIMING OF FRONT WITH THE NAM THE FASTER OF THE MODELS. WILL USE THE SREF WHICH IS CLOSE TO A COMPROMISE BETWEEN THE GFS/NAM. HENCE...WILL BRING LIKELY POPS INTO THE MOUNTAINS DURING THE MORNING AND ELSEWHERE DURING THE AFTERNOON. MAX TEMPS WILL BE ON THE DECLINE DUE TO CLOUDS/STORMS....BUT OUTSIDE OF THE MOUNTAINS TEMPS ARE STILL EXPECTED TO CLIMB INTO THE LOWER TO MID 90S. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... AS OF 230 PM TUESDAY...OVERNIGHT PERIOD WEDNESDAY WILL BEGIN WITH ONGOING CONVECTION AT SOUTHERN END OF RATHER STRONG SHORT WAVE TROUGH MOVING FROM GREAT LAKES TOWARD NEW ENGLAND. SOME TIMING AND DETAIL DIFFERENCES EXIST AMONG MODELS... BUT GFS... NAM... AND SREF INDICATE UNSTABLE AIR... DIVERGENCE ALOFT... AND CONVERGENT FLOW IN BOUNDARY LAYER WILL BE PROGRESSING EASTWARD BETWEEN 00Z AND 06Z THURSDAY. 500 MB TROUGH WILL MOVE INTO NEW ENGLAND AND EASTERN CANADA BY THURSDAY MORNING... BUT APPEARS THAT WEAKNESS IN HEIGHT FIELD AT SOUTHERN END OF TROUGH WILL NOT PROGRESS RAPIDLY EASTWARD. THUS... SURFACE FRONTAL BOUNDARY WILL MOVE OFF COAST OF NORTHEASTERN STATES BUT EXTEND SOUTHWARD INTO CAROLINAS JUST SOUTH OF OUR CWA. BOUNDARY SUFFICIENTLY CLOSE AND MOISTURE DEEP ENOUGH TO SUPPORT SLIGHT CHANCE POPS DURING DAY THURSDAY... PRIMARILY ACROSS SOUTHEAST. HAVE LEANED TOWARD THE GFS DEPICTION OF MOISTURE AND LOW-LEVEL FLOW ON FRIDAY WHICH INDICATES ENOUGH MOISTURE FOR SCATTERED SHOWERS OR THUNDERSTORMS. HAVE CONTINUED LOW CHANCE POPS THROUGH FRIDAY NIGHT DUE PRIMARILY TO APPROACH OF NEXT TROUGH AND FRONT FROM THE WEST. DAYTIME TEMPERATURES SHOULD BE IN 80S AND LOWER 90S... NOT QUITE AS HOT AS EARLIER IN WEEK. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 145 PM TUESDAY...NO SIGNIFICANT CHANGES WERE MADE TO THE GOING FORECAST FOR THE MEDIUM RANGE. I PRIMARILY USED THE 00Z/22 ECMWF FOR THE DETAILS OF THE FORECAST WHICH STILL FEATURES EAST COAST TROUGHING THROUGH THE PERIOD. DID NUDGE MAX TEMPS UP A BIT ON SAT AND SUN AS IT LOOKS LIKE THE EASTERN EXTENSION OF THE STRONG RIDGE OVER THE SOUTHERN PLAINS WILL BRING IN SOME HIGHER HEIGHTS...BEFORE RETROGRADING BACK TOWARDS THE DESERT SOUTHWEST AS A REINFORCING SHOT OF ENERGY AMPLIFIES THE EASTERN CONUS TROUGH EARLY NEXT WEEK. AT THE SURFACE...THE FA WILL REMAIN UNDER THE INFLUENCE OF A MOIST AND UNSTABLE LLVL AIR MASS THROUGH THE PERIOD AS A COLD FRONT SAGS SOUTHWARD MON AND TUES. OVERALL...HPC AND MODEL GUIDANCE CONTINUES TO SUPPORT AN ACTIVE PERIOD WITH A SOLID CHC OF CONVECTION THROUGH TUES. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... VFR CONDITIONS AT 18Z WILL HOLD THROUGH THE AFTERNOON AND MOST OF THE NIGHT. THE EXCEPTION WOULD BE IF A THUNDERSTORM MOVED OVER AN AIR FIELD LATE THIS AFTERNOON OR EVENING. CURRENT INDICATIONS ARE THAT CONVECTIVE DEVELOPMENT WILL BE MOST WIDESPREAD LATE THIS AFTERNOON OVER THE NC MOUNTAINS. THESE STORMS THEN MAY PROPOGATE INTO THE FOOTHILLS AND PIEDMONT DURING THE EVENING. HAVE CONTINUED WITH THE MENTION OF CB IN THE TAFS FROM ABOUT 21Z-01Z EXCEPT 20Z-01Z AT KAVL. SCATTERED THUNDERSTORMS SHOULD DISSIPATE BY 02Z. MOST GUIDANCE INDICATES SOME MINOR RESTRICTION TO VSBY AROUND SUNRISE...SO HAVE INCLUDED HZ AND VSBYS 5-6SM. A COLD FRONT WILL ENTER THE AREA ON WEDNESDAY WHICH IS EXPECTED TO PRODUCE FAIRLY WIDESPREAD COVERAGE OF THUNDERSTORMS DURING THE AFTERNOON. HAVE INCLUDED A CB GROUP AFTER 16Z AT ALL SITES...THOUGH THIS MAY BE A LITTLE EARLY FOR SITES LIKE KAND. OUTLOOK...THUNDERSTORMS WED EVENING WILL MOVE E AND S OF THE REGION OVERNIGHT ALONG WITH ASSOCIATED COLD FRONT. HIGH PRESSURE WILL BRIEFLY BUILD S PROVIDING GENERALLY VFR CONDITIONS THURSDAY INTO FRIDAY. SCATTERED MAINLY AFTERNOON AND EVENING THUNDERSTORMS CAN BE EXPECTED FRIDAY THROUGH SUNDAY. SOME MVFR CEILINGS AND VISIBILITY MAY OCCUR IN THE THUNDERSTORM...WITH MVFR VISIBILITY AT NIGHT IN FOG WHERE RAIN FALLS. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...BSH NEAR TERM...LG SHORT TERM...LGL LONG TERM...BSH AVIATION...LG sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 1057 AM EDT TUE JUL 22 2008 .SYNOPSIS... A WEAK COLD FRONT WILL APPROACH FROM THE NORTHWEST TODAY AND SLOWLY CROSS THE AREA THROUGH WEDNESDAY NIGHT. THIS SYSTEM SHOULD STALL OVER CENTRAL SOUTH CAROLINA AND GEORGIA FOR THE LATTER PART OF THE WEEK...WHILE WEAK HIGH PRESSURE TRIES TO BUILD IN FROM THE NORTH. A REINFORCING COLD FRONT WILL APPROACH FROM THE NORTHWEST AND MOVE OVER THE AREA EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... TEMPS NOT RISING QUITE AS FAST TODAY AS OPPOSED TO YESTERDAY OUTSIDE OF THE MOUNTAINS DUE TO SOME DEBRIS CI AND PROBABLY SOME EVAPORATIVE EFFECTS WHERE THUNDERSTORMS OCCURRED YESTERDAY EVENING. HAVE TWEAKED THE MAX TEMP GRID DOWNWARD A DEGREE OR TWO AS A RESULT. SFC DEWPOINTS SHOULD ACTUALLY INCREASE SOME AS DAY PROGRESSES DUE TO EVAPORATION AND ADVECTION AS WINDS SWING TO THE S THIS AFTERNOON. THEREFORE...HEAT INDEX VALUES WILL STILL BE IN THE VICINITY OF 105...SO SEE NO REASON TO CANCEL THE ADVISORY OUTSIDE OF THE MOUNTAINS. IN REGARD TO CONVECTIVE EXPECTATIONS...THE ATMOSPHERE WILL CERTAINLY BE POTENTIALLY UNSTABLE WITH CAPES INCREASING INTO THE 1000-2000J RANGE. RUC AND 12Z NAM TARGETING MOUNTAINS FOR MOST WIDESPREAD COVERAGE BEGINNING AFTER 18Z AS WEAK SHORT WAVE ARRIVES WITH SOME OF THIS ACTIVITY PROBABLY MOVING INTO THE FOOTHILLS/PIEDMONT AREAS THIS EVENING. ESSENTIALLY JUST MADE SOME MINOR ADJUSTMENTS TO TIMING IN THE POP FIELD. SOME SEVERE STORMS AGAIN POSSIBLE LATE THIS AFTERNOON AND EVENING. DCAPE`S AGAIN LOOK TO BE AROUND 1000J...SO SVR DOWNBURSTS ARE A THREAT AGAIN. INITIAL EVALUATION LOOKS LIKE 50-55DBZ CORES AROUND 28K FT FOR SVR DOWNBURSTS AND AROUND 33K FT FOR SVR HAIL. WARM AND MUGGY CONDITIONS ARE EXPECTED TONIGHT...WITH CONVECTION CHANCES DECREASING THROUGH THE NIGHT. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 230 AM TUESDAY...GFS CONTINUES HAVING CONVECTIVE FEEDBACK ISSUES SO LEANED A BIT MORE TOWARD A NAM/ECMWF BLEND. CLOSED H5 LOW OVER E GREAT LAKES AND ASSOC E US TROF CONTINUE TO DEEPEN WED. AT THE SAME TIME...A WEAK COLD FRONT SINKS S OVER THE FORECAST AREA. ADD DEEP MOISTURE WITH CAPES AROUND 2000J/KG IN THE AFTN AND ALL THE INGREDIENTS ARE THERE FOR LIKELY SHWRS/TSTMS. EVEN THO H5 HEIGHTS DECREASE AND MORE CLOUDS ARE EXPECTED...1000-850MB THICKNESS STAYS FAIRLY HIGH. SO ALTHO GUIDANCE IS COOLER THAN TUE...A MODEL BLEND YIELDS TEMPS STILL ABOVE AVG... RANGING FROM L-M90S TO U80S FOOTHILLS AND PIEDMONT...WITH U70S TO M80S MTNS. NAM/GFS FASTER THAN ECMWF PUSHING FRONT S WED NIGHT-THU AND AM LEANING TOWARD SLOWER ECMWF. UPPER SUPPORT WANES AS H5 TROF BEGINS TO PULL AWAY TO THE NE THU AND SFC FRONT CONTINUES SLOWLY S...SO HAVE POPS TAPERING OFF FROM THE NW DURING THE DAY TO SLIGHT CHANCE. EXPECT HIGHS THU AROUND 90 S CWA...U80S N...WITH U70S-M80S MTNS. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 230 AM TUESDAY...MODELS IN FAIR AGREEMENT PUSHING WEAK SFC BOUNDARY S AND STALLING IT OUT JUST S OF CWA FRI...AS WEAK HIGH PRESSURE TRIES TO BUILD IN FROM THE N. WITH NO SIG AIRMASS CHANGE DIURNALLY DRIVEN SHWRS/TSTMS ARE EXPECTED INTO THE WEEKEND WITH TEMPS WITHIN A DEG OR TWO OF AVG. E COAST TROF DEEPENS AGAIN LATE THIS WEEKEND WHILE A REINFORCING COLD FRONT APPROACHES FROM THE NW. WITH AN H5 SHORTWAVE AND SFC COLD FRONT EXPECTED TO MOVE INTO THE CWA AT THE BEGINNING OF THE WEEK...A CHANCE OF RAIN CONTINUES. && .AVIATION /15Z TUESDAY THROUGH SATURDAY/... WINDS HAVE STAYED UP OVERNIGHT...KEEPING THE LOWER ATMOSPHERE MIXED AND PREVENTING FOG FORMATION. HIGH CEILINGS FROM THE ANVILS OF PREVIOUS THUNDERSTORMS PERSIST AT THE SC TAF SITES. BY MID MORNING WINDS BACK TO THE SOUTHWEST AT 5 KTS...WHILE CUMULUS FORMS WITH DAYTIME HEATING. WINDS BACK FURTHER TO THE SOUTH SOUTHWEST AT MIDDAY...AND THUNDERSTORMS BEGIN TO DEVELOP IN ERNEST. COVERAGE WILL ONLY BE SUFFICIENT TO BE CARRIED IN THE VICINITY OF KAVL...HOWEVER CUMULONIMBUS WILL BE CARRIED AT EACH TAF SITE. BY EARLY EVENING CONVECTION WILL HAVE DIMINISHED...WHILE WINDS BECOME GENERALLY LIGHT AND VARIABLE. ANVIL DEBRIS FORM THUNDERSTORMS WILL BE THE CEILING OVERNIGHT...AS THE MODEL TIME HEIGHTS HAVE BACKED OFF ON LOW CLOUD COVER. MODEL GUIDANCE ONLY CARRIES MVFR FOG AT KAVL...AND ONLY FOR A COUPLE OF HOURS AROUND DAWN ON WEDNESDAY. OUTLOOK...THUNDERSTORM COVERAGE WILL INCREASE AGAIN ON WED AS A COLD FRONT APPROACHES AND MOVES ACROSS THE REGION. BEHIND THE FRONT...GENERALLY VFR CONDITIONS ARE EXPECTED DURING THE DAY ON THU AND CONTINUING ON FRI. ANOTHER FRONT APPROACHES ON SATURDAY...AND CONVECTION ASSOCIATED WITH THIS FEATURE COULD PRODUCE MVFR CEILINGS AND VISIBILITY IN AFTERNOON AND EVENING THUNDER...WITH MVFR VISIBILITY AT NIGHT IN FOG WHERE RAIN FALLS. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...HEAT ADVISORY UNTIL 6 PM EDT THIS AFTERNOON FOR GAZ026-028-029. NC...HEAT ADVISORY UNTIL 6 PM EDT THIS AFTERNOON FOR NCZ070-071-082. SC...HEAT ADVISORY UNTIL 6 PM EDT THIS AFTERNOON FOR SCZ004>014-019. && $$ SYNOPSIS...RB NEAR TERM...LG SHORT TERM...RB LONG TERM...RB AVIATION...LG sc AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 250 PM MDT MON JUL 21 2008 .DISCUSSION...20Z SFC ANALYSIS SHOWSHIGH PRESSURE OVER THE EASTERN DAKOTAS WITH A TROUGH OF LOW PRESSURE EAST OF NORTHERN AND CENTRAL ROCKIES. LATEST RUC ANALYSIS SHOWS MLCAPE UP TO 2000 J/KG OVER SOUTH CENTRAL SOUTH DAKOTA WITH 250-500J/KG OVER NORTHEASTERN SOUTH DAKOTA AND THE PLAINS EAST OF THE BLACK HILLS. OVER NORTHEASTERN WYOMING AND THE BLACK HILLS...MLCAPE VALUES ARE GENERALLY 500-1000J/KG. A RELATIVELY STRONG CAP EXISTS OVER MOST OF WESTERN AND CENTAL SOUTH DAKOTA...WITH A MUCH WEAKER CAP OVER NORTHEASTERN WYOMING AND THE BLACK HILLS. THE CAP IS EXPECTED TO BREAK OVER NORTHEASTERN WYOMING AND THE BLACK HILL...ALLOWING ISOLATED THUNDERSTORMS TO FORM DURING THE LATE AFTERNOON. ORGANIZED SEVERE STORMS ARE NOT EXPECTED. NOCTURNAL CONVECTION MAY DEVELOP IN THE NORTH LATE TONIGHT IN RESPONSE TO 850-700MB THETA-E ADVECTION AHEAD OF SHORTWAVE ENERGY TRAVELING NORTHWARD ALONG THE WESTERN SIDE OF THE UPPER RIDGE AXIS. TUESDAY...UPPER RIDGE PEAKS OVER THE NORTHERN PLAINS AND THEN THE RIDGE AXIS SHIFTS EAST IN RESPONSE TO ENERGY MOVING OUT OF THE CENTRAL BASIN. MLCAPE RISES TO 1-1.5KJ/KG LATE IN THE AFTERNOON WITH MLCIN AROUND 50J/KG. CAP SHOULD HOLD MOST OF DAY UNTIL INFLUENCE OF CENTRAL BASIN SHORTWAVE IS FELT. SHEAR WILL BE MARGINAL...BUT GIVEN IMPULSE AND STEEP LAPSE RATES WOULDN/T BE SURPRISE TO SEE ISOLATED SEVERE WIND GUSTS. WILL AGAIN KEEP TEMPERATURES BELOW POTENTIAL GIVEN SOUTHEASTERLY WINDS. WEDNESDAY...ADDITIONAL ENERGY CROSSES THE AREA PUSHING A COLD FRONT THROUGH THE CWA. THIS WILL BE FOCUS FOR CONVECTION...SOME OF WHICH MAY BE SEVERE IN THE AFTERNOON/EVENING. EXTENDED...AN UPPER LEVEL RIDGE WILL REMAIN OVER THE PLAINS FOR THE LONG TERM. THIS RIDGE WILL BRING SLIGHTLY ABOVE AVERAGE TEMPS. A SERIES OF DISTURBANCES WILL PASS OVER THE RIDGE AND MAY BRING A FEW THUNDERSTORMS TO THE AREA EACH DAY. && .AVIATION...VFR CONDITIONS WILL GENERALLY CONTINUE ACROSS THE AREA THROUGH THIS EVENING. A FEW AFTERNOON AND EVENING STORMS WILL DEVELOP...ESPECIALLY FROM THE BLACK HILLS AREA SOUTH AND WESTWARD. LOCAL MVFR CONDITIONS CAN BE EXPECTED IN AND NEAR ANY STORMS. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. && $$ sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NASHVILLE TN 117 PM CDT MON JUL 21 2008 .DISCUSSION... COMPLEX OF STORMS MOVING SOUTH ACROSS KY AT THIS TIME. CURRENT TRAJECTORY WILL PUT SOME OF THIS ACTIVITY INTO OUR NORTHERN PLATEAU LATER TODAY. LATEST 17Z RUC IS IN SUPPORT OF SPREADING THIS ACTIVITY ACROSS THE PLATEAU. WILL GO AHEAD AND UPDATE AND INCREASE POPS FOR THE NORTHERN AND CENTRAL PLATEAU. WILL ALSO INCREASE POPS SLIGHTLY ACROSS NORTH CENTRAL ZONES. OTW...TEMPS STILL ON TRACK TO REACH THE MID AND UPPER 90S. DEW POINTS HAVE FALLEN SLIGHTLY ACROSS MOST AREAS AND ARE NOW GENERALLY IN THE UPPER 60S. && .OHX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ 21 tn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 104 PM EDT TUE JUL 22 2008 .SYNOPSIS... A WEAK COLD FRONT WILL SLIDE SOUTHEAST INTO THE OHIO VALLEY THIS AFTERNOON AND THEN INTO OUR AREA ON WEDNESDAY. SCATTERED STRONG THUNDERSTORMS ARE EXPECTED THIS AFTERNOON WITH MORE NUMEROUS STORMS EXPECTED ON WEDNESDAY. WEAK HIGH PRESSURE SHOULD BUILD IN BEHIND THE FRONT ON THURSDAY BRINGING DRIER WEATHER FOR WEEKS END. && .NEAR TERM /THROUGH TONIGHT/... ALREADY UPDATED TO LOWER POPS WEST THIS MORNING IN WAKE OF OUTFLOW AND INCREASE IN THE PIEDMONT WHERE OLD BOUNDARY OFF THE MCS HAS STALLED. WITH OLD MCS EXITING TO THE NORTH AND FRONT STILL WELL TO THE NW EXACT COVERAGE OF ADDED CONVECTION IFFY THIS AFTERNOON WITH GUIDANCE OFFERING SEVERAL DIFFERING SOLUTIONS. LATEST NAM APPEARS TOO FAR EAST WITH SIG TSRA THIS AFTERNOON WHILE THE GFS TO THE WEST WITH NEXT ROUND OF TSRA CLOSER TO THE FRONT. LOCAL WRF AND LATEST RUC IN BETWEEN WITH MORE DEVELOPMENT WESTERN SLOPES TO THE BLUE RIDGE WHERE BETTER INSTABILITY LOOKS TO TAKE SHAPE. MODIFIED MORNING RAOBS ALSO SHOW QUITE A BIT OF CAPE WEST UNDER DEEPER RH AND LESS EAST. THINK DEEP BUT RATHER WEAK WESTERLY FLOW COMBO WITH PASSING OUTFLOW MAY DELAY NEW DEVELOPMENT BEFORE NEXT S/W APPROACHES ALLOWING THE FLOW TO BACK MORE SW LATER ON. THIS SUPPORTS BETTER COVERAGE ALONG WEST OF THE BLUE RIDGE WHERE WILL KEEP HIGHEST POPS AND LOW CHANCE EASTERN ZONES. OTRW ANOTHER HOT AFTERNOON IN STORE WITH 850 MB TEMPERATURES RUNNING AROUND +22-23C AND SURFACE DEW POINTS IN THE MID 60S TO LOWER 70S. HOWEVER SIMILAR TO MONDAY THINK DEWPOINTS WILL MIX OUT A BIT ALLOWING HEAT INDICES TO REMAIN JUST BELOW ADVISORY CRITERIA ACROSS THE PIEDMONT. 12Z THICKNESS ALSO IN SUPPORT OF PUSHING HIGHS TO AROUND 100 SE WITH MID/UPR 90S ELSW OVER THE EAST...BUT SLIGHTLY LOWER MID/UPR 80S FAR WEST WHERE WILL SEE MORE CLOUDS/TSRA. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... MORE STRONG STORMS CAN BE EXPECTED ON WEDNESDAY AS A COLD FRONT APPROACHES THE REGION DURING THE AFTERNOON. THE AREA...ESPECIALLY IN THE EAST...WILL BE IN THE ENTRANCE REGION OF THE LOW LEVEL JET. THE COMBINATION OF THE FRONT AND JET DYNAMICS WILL BRING ABOUT ANOTHER ROUND OF SEVERE WEATHER AND HEAVY DOWNPOURS TO THE REGION. PROGRESSION OF THE FRONT MAY BE SLOW TO MOVE TO THE EAST COAST SO WILL HANG ON TO SOME POPS IN THE PIEDMONT THURSDAY MORNING. DRIER SLIGHTLY COOLER AIR WILL MOVING INTO THE REGION ON THURSDAY. BY FRIDAY...THETA-E BOUNDARY BUCKLES BACK TO THE NORTH WITH HEAT AND HUMIDITY INCREASING INTO THE WEEKEND. DEPENDING ON THE TIMING OF PRECIPITATION INTO THE AREA...WE COULD SEE A WIDE RANGE IN TEMPERATURES ACROSS THE AREA. TEMPERATURES COULD RANGE FROM THE LOWER TO MID 70S IN THE GREENBRIER VALLEY TO LOWER 90S IN THE PIEDMONT. && .LONG TERM /SATURDAY THROUGH MONDAY/... UPPER TROUGH OVER THE EAST WILL SLOWLY DEEPEN AND STRENGTHEN OVER THE NEXT SEVERAL DAYS...EVENTUALLY DISPLACING THE HEAT AND HUMIDITY AT LEAST FROM THE NW HALF OF THE CWA BY EARLY NEXT WEEK. WHILE THIS OCCURS...SHWS/TSTORMS SHOULD DEVELOP AHEAD OF IT THIS WEEKEND. A PREFRONTAL TROUGH WILL PASS THROUGH ON SATURDAY FIRST...WITH POSSIBLY MORE NUMEROUS SHOWERS AND STORMS ON SUNDAY WHEN THE COLD FRONT CROSSES. ALTHOUGH MANY COLD FRONTS HAVE PERISHED BEFORE CLEARING THE NC/VA BORDER...IF SOME OF THE LR MODELS VERIFY IN REGARDS TO THE AMPLITUDE OF THE UPPER RIDGE THROUGH SOUTH CENTRAL CANADA...THIS FRONT MAY ACTUALLY PASS FAR ENOUGH SOUTH TO BRING A NICE STRING OF NORMAL OR SLIGHTLY BELOW NORMAL TEMPS...AND DRY CONDITIONS FOR MUCH OF NEXT WEEK. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... WEAK SINKING MOTION BEHIND EARLIER MCS CONTINUES TO SLOW CU AND SUBSEQUENT CONVECTION EARLY THIS AFTERNOON. HOWEVER WITH HEATING EXPECT SOME REDEVELOPMENT OF TSRA ESPCLY OVER THE WEST IN ADVANCE OF NEXT WEAK IMPULSE ADVECTING IN FROM THE TN VALLEY. BUFKIT SUGGESTS MUCH OF THIS MAY HOLD OFF UNTIL AFTER 20Z BUT THEN LINGER SE WVA INTO TONIGHT. THUS WILL SLOW DOWN TIMING OF TSRA ONSET AND INCLUDE VICINITY MENTION MOST SPOTS FROM LATE AFTERNOON THRU 00Z. AREAS OF IFR/MVFR FOG ALSO POSSIBLE ESPCLY VALLEYS WHERE EARLIER RAINFALL OCCURRED. OTRW MAINLY VFR INTO TONIGHT OUTSIDE SHRA. COLD FRONT DROPS IN FROM THE NW WED WITH ONGOING SHRA/TSRA BAND OR QUICK REDEVELOPMENT OF CONVECTION LIKELY TAKING PLACE FROM WEST TO EAST. MAY INCLUDE SOME PREVAILING VSBY REDUCTION IN SE WVA IN THE MORNING OTRW RUNNING WITH CB MENTION BY MIDDAY FAR WEST. CONVECTION LIKELY TO LINGER INTO WED EVENING AS THE FRONT MOVES THROUGH WITH DRYING CONDITIONS ON THU UNDER WEAK HIGH PRESSURE. THIS SHOULD ALSO KEEP VFR CONDITIONS ONGOING INTO LATE WEEK BEFORE ANOTHER COLD FRONT ARRIVES WITH ADDITIONAL SHOWERS AND STORMS BY SAT OR SUNDAY. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/RCS NEAR TERM...JH/RCS SHORT TERM...RCS LONG TERM...KM AVIATION...JH/JS va AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 227 PM CDT TUE JUL 22 2008 .SHORT TERM...TONIGHT THROUGH FRIDAY MAIN FORECAST CONCERNS ARE PRECIPITATION CHANCES WEDNESDAY NIGHT INTO THURSDAY NIGHT. LATEST WATER VAPOR SATELLITE IMAGERY INDICATING UPPER LEVEL TROUGH OVER NORTHEASTERN U.S. AND UPPER LEVEL RIDGE OVER THE NORTHERN PLAINS AND HIGH PLAINS. LATEST WATER VAPOR IMAGERY ALSO INDICATING WEAK SHORTWAVE TROUGH EMBEDDED IN NORTHERLY FLOW ALOFT OVER NORTHEAST WISCONSIN. WITH DAYTIME HEATING AND STEEP LAPSE RATES PER 22.15Z RUC OVER THE REGION...ISOLATED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED OVER NORTHEAST WISCONSIN THIS AFTERNOON. 22.12Z GFS AND NAM INITIALIZE UPPER LEVEL PATTERN AND ASSOCIATED SHORTWAVE TROUGHS PER WATER VAPOR SATELLITE IMAGERY. NO REAL SIGNIFICANT DIFFERENCES NOTED...THOUGH 22.12Z GFS SLIGHTLY FARTHER NORTH WITH MOISTURE TRANSPORT AND CONVERGENCE ASSOCIATED WITH SHORTWAVE TROUGH THURSDAY. THIS WILL HAVE AN IMPACT...AS FAR AS HOW FAR NORTH PRECIPITATION WILL BE THURSDAY ACROSS FORECAST AREA. BOTH MODELS AND 22.09Z SREF FOCUS MESO COMPLEX SYSTEM ACROSS SOUTHERN FORECAST AREA WEDNESDAY NIGHT INTO THURSDAY. CONFIDENCE IN FORECAST WEDNESDAY NIGHT INTO THURSDAY IS LOW...BASED ON EXACT PLACEMENT OF THE MESO COMPLEX SYSTEM. TONIGHT INTO WEDNESDAY...SURFACE RIDGE OVER SOUTHERN ONTARIO CANADA BUILDS SOUTHWARD ACROSS FORECAST AREA 18Z WEDNESDAY. ISOLATED SHOWERS AND THUNDERSTORMS ASSOCIATED WITH SHORTWAVE TROUGH OVER NORTHEAST WISCONSIN WILL BEGIN TO DIMINISH BY SUNSET...AS LOSS OF DAYTIME INSTABILITY AND SUBSIDENCE UNDER SURFACE RIDGE MOVES OVER THE REGION AFTER 03Z. HAVE INTRODUCED ISOLATED SHOWERS AND THUNDERSTORMS THROUGH 03Z WEDNESDAY ACROSS THE NORTHEAST FORECAST AREA. SURFACE RIDGE BUILDS EAST OF FORECAST AREA WEDNESDAY NIGHT INTO THURSDAY AND NEXT SHORTWAVE TROUGH EJECTS OUT OF THE UPPER LEVEL TROUGH OVER THE PACIFIC NORTHWEST AND FLATTENS UPPER LEVEL RIDGE. THIS WILL RESULT IN RETURN OF SOUTHERLY FLOW AND MOISTURE INTO THE FORECAST AREA AFTER 06Z THURSDAY. BOTH THE 22.12Z GFS AND NAM IN GOOD AGREEMENT WITH MOVING SHORTWAVE TROUGH INTO THE NORTHERN PLAINS AND UPPER MIDWEST WEDNESDAY NIGHT INTO THURSDAY...AND FOCUS MOISTURE TRANSPORT AND CONVERGENCE INTO THE SOUTHERN PORTIONS OF THE FORECAST AREA AFTER 12Z THURSDAY. BOTH MODELS DO INDICATE BEST INSTABILITY AND SHEAR ASSOCIATED WITH SHORTWAVE TROUGH TO BE SOUTH AND WEST OF FORECAST AREA. AT THIS TIME...NOT EXPECTING ANY SEVERE POTENTIAL WITH THUNDERSTORMS. WITH BOTH MODELS INDICATING DECENT LIFT AND CONVERGENCE WITH SHORTWAVE TROUGH...HAVE INCREASED PRECIPITATION CHANCES ACROSS THE SOUTHERN FORECAST AREA 12Z THURSDAY TO 00Z FRIDAY. BOTH MODELS INDICATE SURFACE COLD FRONT TO TRACK ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION AND UPPER LEVEL TROUGH TO BEGIN DIGGING OVER THE UPPER GREAT LAKES REGION THURSDAY NIGHT INTO FRIDAY. BOTH THE MODELS INDICATING WEAK MOISTURE CONVERGENCE ALONG SURFACE FRONT. HAVE KEPT SMALL PRECIPITATION CHANCES ACROSS FORECAST AREA THURSDAY NIGHT INTO FRIDAY. .LONG TERM...FRIDAY NIGHT THROUGH TUESDAY MAIN FORECAST CONCERNS ARE PRECIPITATION CHANCES FRIDAY NIGHT INTO SATURDAY...THEN TEMPERATURES THE REST OF THE PERIOD. THE 22.00Z GFS AND ECMWF ARE IN GOOD AGREEMENT IN DIGGING UPPER LEVEL TROUGH OVER THE GREAT LAKES REGION AND SOUTHERN ONTARIO THROUGH PERIOD. THE BIGGEST DIFFERENCE BETWEEN THE MODELS IS THE GFS MUCH STRONGER AND SLOWER MOVEMENT THAN THE ECMWF WITH THE SHORTWAVE TROUGH EMBEDDED IN NORTHWEST FLOW ON BACKSIDE OF UPPER LEVEL TROUGH FRIDAY NIGHT AND SATURDAY. THIS WOULD ALLOW FOR DEEPER MOISTURE AND STRONGER LIFT OVER MUCH OF THE FORECAST AREA FRIDAY NIGHT AND INTO SATURDAY. ENSEMBLES INDICATE HIGH VARIABILITY IN THE STRENGTH OF THE SHORTWAVE TROUGH AND INDICATES THE AXIS OF MEASURABLE PRECIPITATION PROBABILISTIC WILL BE JUST SOUTH AND EAST OF FORECAST AREA FRIDAY NIGHT AND SATURDAY. AT THIS TIME...WILL CONTINUE WITH DRY FORECAST ACROSS FORECAST AREA. THEN...BOTH MODELS ARE IN MUCH BETTER AGREEMENT IN BUILDING SURFACE/UPPER LEVEL RIDGE INTO THE UPPER MIDWEST AND GREAT LAKES REGION SUNDAY INTO EARLY NEXT WEEK. COLDER AIR FILTERS IN BEHIND SHORTWAVE TROUGH/SURFACE COLD FRONT SUNDAY ACROSS THE UPPER GREAT LAKES AND UPPER MIDWEST REGION. BOTH THE 22.00Z GFS AND ECMWF INDICATING 850MB TEMPERATURES FROM PLUS 10 DEGREES CELSIUS TO PLUS 15 DEGREES CELSIUS ACROSS FORECAST AREA. GOOD SUBSIDENCE AND COOLER AIR MASS OVER FORECAST AREA...WILL CONTINUE WITH TREND OF UNSEASONABLY COOLER TEMPERATURES AND DRIER WEATHER INTO EARLY NEXT WEEK. && .AVIATION... GENERALLY VFR CONDITIONS EXPECTED ACROSS THE TAF SITES THROUGH WEDNESDAY. ONLY ITEM WE ARE MONITORING IS THE VALLEY FOG POSSIBILITY FOR THE MISSISSIPPI RIVER AND WISCONSIN RIVER VALLEYS FOR WEDNESDAY MORNING. HAVE INTRODUCED AN MVFR TEMPO PERIOD AT KLSE FOR THIS CHANCE. THE DRYING NORTHEAST WIND WILL WORK AGAINST THE FOG FORMATION...BUT HIGHER SOIL MOISTURE AND PLANT EVAPOTRANSPIRATION WILL WORK TOWARD BETTER FOG CHANCES. OVERALL WIND FIELD IS ABOUT 5 KTS THROUGH THE LOWEST 2KFT UNDER CLEAR SKIES. FOG MAY BE LOCALIZED TO THE MAIN CHANNEL OF THE MISS RIVER AND OFF OF THE KLSE FIELD PROPER. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT/LONG TERM...DTJ AVIATION..........DAB wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 403 AM CDT TUE JUL 22 2008 FORECAST FOCUS ON PRECIPITATION CHANCES TODAY...COOLER AND LESS HUMID AIRMASS NEXT FEW DAYS. LATEST WATER VAPOR IMAGERY INDICATED AN ELONGATED UPPER LEVEL TROUGH OVER THE WESTERN GREAT LAKES REGION...WITH AN UPSTREAM RIDGE OVER THE WESTERN HIGH PLAINS. RUC ANALYSIS INDICATED A VORTICITY MAXIMUM WITHIN THE TROUGH...CENTERED OVER NORTHEAST MINNESOTA. AT THE SURFACE...CANADIAN HIGH PRESSURE WAS LOCATED ACROSS NORTHERN ONTARIO CANADA...MOVING SLOWLY SOUTH. A LOW CLOUD DECK WITH EMBEDDED RAIN SHOWERS WAS MOVING SOUTHWEST FROM THE DOOR COUNTY AREA. .SHORT TERM...TODAY THROUGH THURSDAY... PATCHY FOG SEEN OVER PORTIONS OF THE FORECAST AREA...WITH LIGHT WINDS AND MAINLY CLEAR SKIES. WILL CARRY EARLY MORNING FOG WORDING UNTIL DAYTIME HEATING PICKS UP. MORNING SHIFT WILL HAVE TO WATCH FOR LOW STRATUS DECK AND ASSOCIATED SHOWERS FROM NORTHEAST WISCONSIN MOVING INTO THE AREA. THINK THAT DAYTIME HEATING LATER THIS MORNING COMBINED WITH SLOW MOVEMENT OF DECK SHOULD PREVENT THIS AREA FROM MAKING IT THIS FAR SOUTH. AFOREMENTIONED VORTICITY MAXIMUM IS EXPECTED TO DROP SOUTHEAST ACROSS SOUTHERN WISCONSIN THIS AFTERNOON. THIS FEATURE SHOULD COMBINE WITH MEAN LAYER CAPE VALUES OF AROUND 500 J/KG TO BRING CHANCES FOR SHOWERS AND THUNDERSTORMS. WILL GO SHOWERS THIS MORNING...AND HOLD OFF ON THE THUNDER UNTIL THE AFTERNOON. CORE OF CANADIAN HIGH PRESSURE THEN DROPS THROUGH THE REGION TONIGHT THROUGH WEDNESDAY NIGHT. THIS FEATURE SHOULD BRING DRY CONDITIONS...A COOLER AND DRIER AIRMASS AND LIGHT WINDS. WEAK COLD AIR ADVECTION...WITH 1000/500MB THICKNESSES DROPPING INTO THE UPPER 550S TO MID 560S DKM RANGE TODAY...SHOULD BRING COOLER TEMPERATURES TO THE AREA. DEW POINTS SHOULD ALSO DROP INTO THE UPPER 50S TO AROUND 60 FAHRENHEIT...WHICH SHOULD MAKE FOR A LESS HUMID DAY. THE PASSING HIGH SHOULD ALLOW FOR NORTH TO NORTHEAST WINDS TO OCCUR NEAR THE LAKE TODAY AND WEDNESDAY...KEEPING HIGHS THERE IN THE UPPER 60S TO LOWER 70S. 1000/500MB THICKNESSES THEN RISE BACK INTO THE MID TO UPPER 560S DKM RANGE TONIGHT AND WEDNESDAY...WITH A SLOW MODERATION IN TEMPERATURES THROUGH THURSDAY AWAY FROM THE LAKE. LIGHT WINDS AND RADIATIONAL COOLING CONDITIONS SHOULD ALLOW FOR AT LEAST PATCHY FOG TO FORM TONIGHT AND WEDNESDAY NIGHT...ESPECIALLY IN THE RIVER VALLEYS AND LOW LYING AREAS. IF DEW POINTS STAY HIGHER THAN EXPECTED...COULD SEE SOME DENSE FOG IN SPOTS. NEXT CHANCE OF PRECIPITATION COMES LATE THURSDAY IN THE WESTERN COUNTIES...AS FOCUSED WARM AIR ADVECTION IN THE LOW LEVELS APPROACHES. .LONG TERM...THURSDAY NIGHT THROUGH MONDAY... POPS CONTINUE THURSDAY NIGHT WITH THE WARM AIR ADVECTION...AND FRIDAY AS A VORTICITY MAXIMUM PASSES JUST NORTH OF THE AREA. AFTER THAT...THE UPCOMING WEEKEND APPEARS DRY FOR NOW...WITH ANOTHER CANADIAN HIGH PRESSURE SYSTEM WORKING INTO THE AREA. && .AVIATION... AREAS OF IFR AND PATCHY LIFR IN FOG THIS MORNING UNTIL JUST AFTER 14Z. MID LEVEL TROF AXIS WILL SWING ACROSS THE FORECAST AREA TODAY. ENOUGH MOISTURE BELOW 15 THSD FT...SO EXPECT SOME CU/SC WITH A SCATTERED SHOWERS/ISOLATED THUNDERSTORMS MAINLY IN THE AFTERNOON. SOME MVFR CIGS EXPECTED. && .MARINE... SOME MORNING FOG. THEN NORTH TO NORTHEAST WINDS WILL INCREASE. WAVES MAY APPROACH SMALL CRAFT CRITERIA THIS AFTERNOON AND TONIGHT. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && $$ SHORT/LONG TERM...08/WOOD AVIATION/MARINE...06/HENTZ wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 334 AM CDT MON JUL 21 2008 .SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT FORECAST CONCERNS THIS PACKAGE...SMALL MAINLY AFTERNOON/EVENING -SHRA/-TSRA CHANCE TODAY/TUE...TEMPERATURES THRU THE PERIOD. 06Z DATA ANALYSIS HAD LOW PRESSURE OVER LOWER MI WITH A TROUGH WEST INTO SOUTHERN WI. ANOTHER BROADER AREA OF LOW PRESSURE WAS OVER THE WESTERN PLAINS WITH A TROUGH/FRONT EAST ACROSS SOUTHERN NEB TO SOUTHERN IA. BROAD BUT WEAK HIGH PRESSURE WAS CENTERED OVER MN. LOW LEVEL JET/MOISTURE TRANSPORT/THETA-E CONVERGENCE AND FAVORABLE 300MB JET AGEOSTROPHIC FLOW/DIVERGENCE ALOFT EARLY THIS MORNING FUELING A SEVERE CONVECTIVE COMPLEX ACROSS NORTHEAST NEB/WESTERN IA. COMPLEX TRACKING EAST-SOUTHEAST ACROSS IA...ALONG 850MB MOISTURE TRANSPORT/ THETA-E CONVERGENCE AXIS. SCT -SHRA/TSRA OCCURRING ACROSS EASTERN SD...IN WEAK 700MB MOISTURE TRANSPORT/THETA-E CONVERGENCE AND AHEAD OF ANOTHER SHORTWAVE. 21.00Z NAM/GFS INITIALIZED REASONABLY WELL. MODELS OFFER RATHER SIMILAR SOLUTIONS FOR TODAY THRU WED NIGHT...BUT NOT WITHOUT SOME MESO-SCALE DIFFERENCES. DPROG/DT OF 500MB HGTS AT 21.00Z SHOWED NAM/GFS RUNS OF 19.00Z AND 20.00Z VERIFIED REASONABLY WELL ACROSS NOAM/EASTERN PAC. BETTER RUN-TO-RUN CONSISTENCY TO GFS WITH THE TROUGH OVER EASTERN CAN...AND TO NAM WITH THE LOW OFF THE CA COAST. THRU 60HRS TREND IS STRONGER/MORE PERSISTENT WITH TROUGHING OVER THE WESTERN GREAT LAKES BUT MORE PROGRESSIVE WITH SHORTWAVES/ TROUGHING INTO THE WESTERN CONUS. MODEL RUN-TO-RUN CONSISTENCY SUFFERS IN THE 60-84HR TIME-FRAME. TROUGHING/UPPER LOW OVER THE GREAT LAKES MUCH MORE PERSISTENT THAN EARLIER RUNS...AND MODELS STRUGGLING WITH TIMING/STRENGTH OF SHORTWAVES IN THE FLOW OVER THE WESTERN HALF OF NOAM. CHECK OF OBS VS. MODEL DATA AT 06Z SHOWED NAM/GFS REASONABLE WITH THE SFC MASS FIELDS OVER THE CENTRAL CONUS. PER WV IMAGERY...NAM APPEARED BETTER WITH THE SHORTWAVE DETAILS FROM ND TO SASKAT/MAN AND HUDSONS BAY AREA...BUT APPEARED OVERDONE WITH A FEATURE NEAR THE SD/NEB BORDER. PER MODEL QPF AND RADAR TRENDS AROUND 06Z...BOTH MODELS STRUGGLING WITH THE CONVECTIVE COMPLEX OVER NEB/IA. GFS NOT GOOD BUT BETTER THAN NAM THRU 06Z. NAM LOOKING BETTER IN THE 06Z-12Z TIME-FRAME. LOCAL WRF MODEL DOING BETTER WITH NEB/IA CONVECTION AT 06Z. HOWEVER...THESE 3 MODELS STRUGGLING WITH CONVECTION OVER EASTERN SD AHEAD OF SHORTWAVE... WHILE LOCAL RUC-WRF MODEL HANDLING THE EASTERN SD CONVECTION QUITE WELL. THUS...NO CLEAR MODEL FAVORITE THIS CYCLE AND TREND TOWARD A MODEL/ ENSEMBLE BLEND. GIVEN FORECAST HINGING ON NUMEROUS MESO-SCALE DETAILS...CONFIDENCE ONLY AVERAGE THIS CYCLE. FOR THE SHORT TERM...FORCING FOR CONVECTION ACROSS IA WEAKENS/MOVES SOUTH THIS MORNING AS LOW LEVEL JET VEERS AND UPPER JET AXIS SHIFTS SOUTH OF THE AREA...ALLOWING THIS CONVECTION TO DROP SOUTH OF THE FORECAST AREA. PER WV IMAGERY...MODELS LOOK TOO WEAK WITH THE SHORTWAVE AIDING CONVECTION OVER EASTERN SD. THIS WAVE MOVES EAST THIS MORNING...HOWEVER WEAK 850-700MB MOISTURE TRANSPORT/THETA-E CONVERGENCE WITH IT WEAKENS THRU 12Z AND DROPS SOUTHEAST INTO IA. MAY YET NEED A SMALL RAIN CHANCE OVER THE SOUTHWEST END OF THE FORECAST AREA EARLY THIS MORNING. 850-700MB TEMPS COOL OVER THE AREA TODAY AS TROUGHING OVER THE WESTERN GREAT LAKES AMPLIFIES. THIS COMBINED WITH DIURNAL WARMING AND STEEP LOW LEVEL LAPSE RATES RESULTS IN AFTERNOON MIXED-LAYER CAPES OF 500-1000 J/KG. CONTINUED SMALL -SHRA/TSRA CHANCE FOR THE AFTERNOON HOURS TODAY...THEN CONFINED IT TO NORTHEAST END OF THE FORECAST AREA...UNDER COOLER MID LEVEL TEMPS...FOR THE EVENING HOURS. STRONGER SHORTWAVE SEEN IN WV IMAGERY NEAR JAMES BAY DROPS ACROSS THE AREA FOR TUE AFTERNOON. MODEL SOUNDINGS AGAIN INDICATE STEEP LOW LEVEL LAPSE RATES AND COOL MID LEVEL TEMPS WITH DIURNAL HEATING RESULTING IN MIXED-LAYER CAPES OF AROUND 500 J/KG FOR TUE AFTERNOON. THIS PLUS THE SHORTWAVE...A SMALL -SHRA/TSRA CHANCE FOR TUE AFTERNOON APPEARS WARRANTED FOR NOW. DRIER AIRMASS/HIGH PRESSURE SETTLE OVER THE AREA ON WED FOR A DRY... QUIET DAY. WITH THE LESS PROGRESSIVE PATTERN/TROUGHING REMAINING OVER THE GREAT LAKES AND WEAK RIDGING ALOFT OVER THE NORTHERN PLAINS...RAIN CHANCES WED NIGHT MAY WELL HOLD OFF UNTIL THU. TRIMMED RAIN CHANCE ON EAST END OF FORECAST AREA FOR WED NIGHT BUT LEFT A SMALL CHANCE ACROSS CENTRAL AND WESTERN PARTS FOR NOW TO BLEND WITH NEIGHBORING GRIDS. TRENDED TOWARD A BLEND OF GUIDANCE HIGHS TODAY/TUE. WITH LIGHT WINDS AND MOSTLY CLEAR SKIES LATER TONIGHT...TRENDED TOWARD COOLER OF GUIDANCE LOWS. FAVORED A BLEND OF GUIDANCE LOWS TUE NIGHT. WITH PLENTY OF SUNSHINE EXPECTED WED...FAVORED WARMER OF GUIDANCE HIGHS AND RAISED THESE A BIT WHICH BLENDS WELL WITH SURROUNDING GRIDS. WITH CLEAR TO PARTLY CLOUDY SKIES MUCH OF WED NIGHT AND LIGHT WINDS...TRENDED LOWS DOWN A FEW DEGREES TOWARD 21.00Z GFS MEX MOS VALUES. .LONG TERM...THURSDAY THROUGH SUNDAY 21.00Z MEDIUM RANGE MODEL RUNS/GFS ENSEMBLE MEAN IN REASONABLY GOOD AGREEMENT WITH EACH OTHER FOR THE THU THRU SUN PERIOD. TREND IS LESS PROGRESSIVE AND MORE AMPLIFIED WITH THE FLOW PATTERN ACROSS NOAM... ESPECIALLY BY SAT/SUN. THIS LEAVE THE UPPER MIDWEST MORE UNDER NORTHWEST FLOW THRU THE DAY 4-7 PERIOD. THE SLOWER...MORE BLOCKY FLOW PATTERN OVER EASTERN NOAM WOULD DELAY THE RAIN CHANCE INTO THE AREA THU...WITH RAIN CHANCES INTO FRI AND PERHAPS SAT. TREND WOULD ALSO BE A BIT COOLER/DRIER FOR THE WEEKEND WITH REGION UNDER NORTHWEST FLOW ALONG AND A CANADIAN HIGH LOOKING TO DROP SOUTH ACROSS THE REGION. DID NOT MAKE ANY CHANGES TO DAYS 4-7 GRIDS FOR NOW. LEFT THIS TO DAY CREW...WHICH WILL HAVE HELP OF NATIONAL DISCUSSIONS/ GUIDANCE TO HELP SORT OUT THE DETAILS/MODEL TRENDS AND MAKE NEEDED CHANGES. && .AVIATION...TODAY AND TONIGHT NWLY FLOW AND SEVERAL WEAK DISTURBANCES THROUGH THIS FLOW WILL SERVE TO KEEP SMALL/ISOLD THREATS OF THUNDERSTORMS THROUGH THE NEXT COUPLE OF DAYS...THOUGH NOT NEARLY WITH ENOUGH COVERAGE/CERTAINTY TO INCLUDE IN TAFS AT EITHER SITE. GENERALLY VFR CONDITIONS THROUGH THE TAF PERIOD EXPECTED WITH LIGHT NWLY/NLY FLOW...GRADUALLY BACKING TO NORTHEAST AND EAST THROUGH THE PERIOD AS SURFACE HIGH BUILDS SOUTH INTO WESTERN GREAT LAKES. CURRENTLY WATCHING SCT SHRA/TSRA ACTIVITY OVER EASTERN SD WITH LOW CONFIDENCE THIS WILL HOLD TOGETHER ALL THE WAY TO KRST...BUT SHOULD SEE BKN-OVC100-150 CEILINGS THROUGH THE MORNING HOURS. OTHERWISE...ISOLD/SCT STORMS IN PEAK HEATING /2PM-10PM/ OF LOW PREDICTABILITY AND COVERAGE AND WILL LEAVE OUT OF FORECAST FOR NOW. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT/LONG TERM...RRS AVIATION..........BINAU wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 335 AM EDT WED JUL 23 2008 .SYNOPSIS...WATER VAPOR IMAGERY SHOWS A MID TO UPPER TROUGH FROM THE GREAT LAKES TO THE LOWER MS VALLEY AND A WEAK SHORTWAVE OFF THE SE U.S. COAST PER RUC AND NAM GUIDANCE. AT SFC...RIDGE AXIS IS ACROSS CENTRAL FL AND ANTICIPATE LITTLE CHANGE IN THIS FEATURE FOR THE NEXT 3 DAYS. JAX SOUNDING FROM 00Z SHOWED PWAT OF ABOUT 2 INCHES AND MEAN 0-6KM WINDS FROM THE NW AT 5 KT. CONSIDERABLE MID AND UPPER LEVEL DEBRIS CLOUDINESS BLANKETS PORTIONS OF THE AREA FROM EARLIER CONVECTION OVER THE SE CONUS. ANTICIPATE A FEW AREA PLACES OVER THE SRN ZONES TO DEVELOP PATCHY FOG THROUGH SUNRISE DUE TO WET GROUNDS FROM YESTERDAYS RAINFALL. RADAR IMAGERY SHOWS A FEW SHOWERS AND STORMS ALREADY FORMING JUST S OF THE FORECAST AREA. .SHORT TERM...TODAY...CLOUDINESS AND LOWER HEIGHTS WILL TRANSLATE INTO LOWER MAX TEMPS THAN THE PAST FEW DAYS. ANTICIPATE HIGHS OF UPPER 80S TO LOWER 90S. MAV POPS HAVE JUMPED UP TO 70-80% FOR TODAY WHICH LOOKS TOO HIGH. WILL GO CLOSER TO NAM GUIDANCE AND HAVE LOW END LIKELY OVER MOST AREAS. NAM SHOWS MORE THAN 2 IMPULSES AFFECTING THE REGION TODAY COMING IN FROM THE NW AND WITH DAYTIME HEATING AND SEA BREEZES THE LIKELY POPS SEEM REASONABLE. MODIFIED SOUNDING YIELDS CAPE VALUES CLOSE TO 2500 J/G AND LI OF -6. GIVEN THE RELATIVE HIGH PWAT AIR AND WEAK 0-6KM WINDS MAIN THREATS TODAY APPEAR TO BE LOCALLY HEAVY RAINFALL AND MARGINALLY SEVERE DOWNBURST WINDS. IN ADDITION...STORMS DON`T LOOK TO BE AS INTENSE AS THEY WERE ON TUE DUE TO WARMER TEMPS AT 500 MB AND GENERALLY LOWER INSTABILITY VALUES. TONIGHT...SHORTWAVE IMPULSES CONT TO AFFECT THE AREA TONIGHT AND BEST DYNAMIC LIFT WILL BE OVER NE FL. WILL GO WITH A BLEND OF THE GUIDANCE BUT LEAN A BIT TOWARD THE MAV POPS WHICH HAVE BEEN CONSISTENTLY AROUND 40% FOR TONIGHT. THURSDAY...THE WEAK TROUGH THAT IS N OF THE AREA WILL BE SAGGING SWD AND RESULT IN CONTINUED MOISTURE POOLING OVER THE AREA...MOST FAVORED OVER NE FL. WILL GO WITH POPS AROUND 40-50% OVER NE FL AND 30-40% FOR SE GA WHICH IS A CONSENSUS OF THE GUIDANCE. TEMPS SHOULD BE A BIT WARMER AS HEIGHTS RISE A BIT. THU NIGHT...MID LEVEL RIDGING TRIES TO BUILD IN AND SFC TROUGH WILL DRIFT INTO CENTRAL GA. PLANNING ON POPS AT 20-30% FOR MAINLY EVENING CONVECTION. FRIDAY...MID LEVEL HEIGHTS CONT TO BUILD AS THE SE CONUS TROUGHING WANES. ENOUGH MOISTURE TO WORK WITH FOR SCT POPS AREA WIDE...THOUGH LOWER CHANCES FOR SE GA WHERE WEAKER FORCING AND LOWER MOISTURE IS LOCATED. TEMPS IN THE LOWER 90S EXPECTED WITH FEW POCKETS OF MID 90S. .LONG TERM...SAT-TUE. SFC RIDGE CONTS OVER CENTRAL FL FOR THE WEEKEND. LATEST GFS SHOWS ERN COAST TROUGHING TO BECOME RE-ESTABLISHED WITH LOWERING HEIGHTS AND THUS SUSTAINING A CHANCE OF SHOWERS AND THUNDERSTORMS FOR THE EXTENDED FORECASTS. FOR NOW WILL KEEP POPS IN THE 30-40% RANGE EACH DAY AND SHOW JUST A SLIGHT CHANGE IN TEMPS MOVING CLOSE TO OR JUST BELOW CLIMO. && .AVIATION...MAY SEE BRIEF PERIOD OF MVFR VISIBILITY EARLY THIS MORNING (09Z-12Z) DUE TO FOG. OTHERWISE AN ACTIVE AFTERNOON EXPECTED ACROSS THE AREA AS THE NEXT SHORT WAVE MOVES IN. CONFIDENCE IS HIGH THAT THUNDERSTORMS WILL BE IMPACTING ALL OF THE TERMINALS AND HAVE INCLUDED VCTS BY 18Z AND TEMPO GROUPS FOR TS AND GUSTY WINDS BETWEEN 19Z-22Z. && .MARINE...SW TO S WINDS EXPECTED FOR MUCH OF THE WEEK AS HIGH PRESSURE RIDGE REMAINS NEAR CENTRAL FLORIDA. NOCTURNAL SURGES AT NIGHT BUT BELOW SCEC CRITERIA. SEAS 2-4 FT. MAIN CONCERN WILL BE SCATTERED AFTERNOON STORMS WITH STRONG WIND POTENTIAL MOVING OFFSHORE. && .PRELIMINARY POINT TEMPS/POPS... AMG 91 71 93 72 / 60 30 30 20 SSI 88 75 89 76 / 50 40 30 20 JAX 90 71 91 73 / 60 40 40 30 SGJ 87 71 88 74 / 60 40 40 30 GNV 89 71 90 73 / 60 40 50 30 OCF 89 71 90 72 / 60 40 50 30 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...NONE. GA...NONE. AM...NONE. && $$ SHASHY/PETERSON fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 338 AM CDT WED JUL 23 2008 .DISCUSSION... 335 AM CDT QUIET WEATHER WILL CONTINUE TODAY AND TONIGHT...AND THEN ATTENTION WILL SHIFT TO NEXT CHANCE OF PRECIP FOR LATE THURSDAY AFTERNOON...AND ESPECIALLY INTO THURSDAY NIGHT. WATER VAPOR IMAGERY/RUC ANALYSES INDICATING LAST IN SERIES OF STRONGER UPPER LEVEL SHORT WAVES ROTATING THROUGH SOUTHERN LOWER MICHIGAN/NORTHERN INDIANA EARLY THIS MORNING. ANOTHER SHORT WAVE TROUGH ACROSS JAMES BAY IS ROTATING BACK WESTWARD AROUND THE LONGWAVE TROUGH...BUT THE EXPECTED TRACK OF THIS VORT WILL KEEP IT WELL EAST OF THE AREA. OTHERWISE...BROAD SURFACE ANTICYCLONE ACROSS SOUTHERN ONTARIO WILL CONTINUE TO SETTLE INTO WESTERN GREAT LAKES TODAY. FORECAST SOUNDINGS SUGGEST STRENGTHENING INVERSION IN THE 800-750 HPA LAYER THIS AFTERNOON WHICH SEEMS REASONABLE GIVEN STRENGTHENING SYNOPTIC SCALE SUBSIDENCE BEHIND THIS AFOREMENTIONED VORT MAX TODAY. WITH RELATIVELY DRY LOW LEVELS/SUBSIDENCE...CU COVERAGE SHOULD BE LIMITED TODAY AND FORMING MOSTLY LIKELY AWAY FROM LAKE MICHIGAN. LOW LEVEL THERMAL PROGS SUGGEST HIGHS TODAY IN THE BALLPARK FROM YESTERDAY...PERHAPS A FEW DEGREES WARMER IN MOST LOCATIONS GIVEN SLIGHTLY DEEPER MIXED LAYER TODAY. NORTH WINDS WILL CONTINUE TO PROVIDE LAKE COOLING AND HIGHS NEAR THE LAKE MICHIGAN SHORELINE SHOULD ONCE AGAIN RISE INTO MID 70S. ELSEWHERE HIGH TEMPERATURES OF AROUND 80 ARE EXPECTED. DECOUPLING WILL OCCUR EARLY THIS EVENING...AND WITH A RELATIVELY DRY AIR MASS IN PLACE TEMPERATURES WILL DROP OFF FAIRLY SHARPLY EARLY THIS EVENING WITH A GOOD RADIATIONAL COOLING SETUP. HAVE CONTINUED IDEA OF MID TO UPPER 50S FOR LOWS TONIGHT...ALTHOUGH SOME LOCALLY COOLER READINGS ARE POSSIBLE IN THE 50 TO 55 DEGREE RANGE. ATTENTION FOR THURSDAY WILL THEN SHIFT TO INCREASINGLY FAVORABLE SETUP FOR PRECIPITATION. MOISTURE PROFILE WILL BE INITIALLY QUITE MEAGER ACROSS THE AREA EARLY THURSDAY AND GIVEN FAIRLY LARGE AMPLITUDE TROUGH TO THE EAST...THE SFC RIDGE AXIS WILL BE RATHER SLOW TO EXIT. NAM OVER PAST FEW DAYS HAS BEEN CONSIDERABLY FASTER IN BRINGING SIGNIFICANT LOW LEVEL WARM/MOIST ADVECTION INTO NORTHERN ILLINOIS DURING THE DAY THURSDAY. HOWEVER LATEST FEW RUNS OF NAM ARE SEEMINGLY COMING AROUND TO MORE OF A GFS IDEA IN A SLOWER ONSET OF WAA/THETA-E ADVECTION FORCING. HAVE CONTINUED TO FOLLOW GFS IDEA WITH BRINGING HIGHER CHANCE POPS INTO NORTHERN ILLINOIS BY THURSDAY EVENING. DID MAINTAIN SOME LOW CHANCE POPS ACROSS FAR WESTERN PORTIONS OF THE CWA FOR THURSDAY AFTERNOON...ALTHOUGH ANY INSTABILITY WILL BE QUITE ELEVATED AND INITIAL WAA/MID LEVEL FRONTO FORCING WILL LIKELY BE SPENT WITH IN LOW/MID LEVEL SATURATION. CONCERN FOR THURSDAY NIGHT MAY END UP BEING MORE TOWARD HEAVY RAINFALL POTENTIAL WITH PWATS INCREASING BACK INTO THE 1.75 TO 2.00 INCH RANGE AGAIN...ESPECIALLY ACROSS SOUTHERN PORTIONS OF THE AREA. LARGER SCALE PATTERN DOES APPEAR TO CONTINUE TO FAVOR SOUTHEAST PROPAGATION OF ANY MCS THAT FORMS TO THE WEST THURSDAY EVENING...SO NORTH-SOUTH POP GRADIENT FOR THURSDAY NIGHT SEEMS APPROPRIATE AT THIS TIME. DID CONTEMPLATE GOING WITH LIKELY POPS ACROSS THE FAR SOUTH BUT AT THIS DISTANCE HAVE INCREASED TO HIGHER END CHANCE POPS. WITH MAIN LOW LEVEL THERMAL RIDGE REMAINING OFF TO THE WEST OF THE AREA THURSDAY NIGHT...MID LEVEL LAPSE RATES SHOULD BE ON THE WEAK SIDE AND INSTABILITY PROGS AT THIS TIME DO NOT SEEM SUPPORTIVE OF A SUBSTANTIAL SEVERE WEATHER THREAT. ON FRIDAY...DETAILS ON PRECIP POTENTIAL BECOME MORE BLURRY DUE TO THE EFFECTS OF THURSDAY NIGHT CONVECTION ON MESOSCALE FACTORS. GFS/NAM ARE IN GENERAL AGREEMENT IN WEAK SFC TROUGH APPROACHING FAR NORTHERN ILLINOIS DURING THE AFTERNOON ASSOCIATED WITH AN UPPER LEVEL SHORT WAVE APPROACHING THE NORTHERN GREAT LAKES. MAY ALSO HAVE ANOTHER BOUNDARY TO THE SOUTH LEFT OVER FROM OVERNIGHT CONVECTION. MAGNITUDE OF INSTABILITY ALSO IN QUESTION DEPENDING IN EXTENT OF REMNANT CLOUD COVER. GIVEN ALL THESE UNCERTAINTIES...MAINTENANCE OF BROADBRUSH LOW END CHANCE POPS STILL SEEM IN ORDER FOR FRIDAY. MAIN SURFACE FRONT WILL LIKELY STALL OUT SOMEWHERE JUST SOUTH OF THE FORECAST AREA ON SATURDAY AS MAIN MID/UPPER LEVEL FORCING RACES EAST INTO THE NORTHEAST US. LATER FORECASTS MAY NEED TO CONSIDER ADDING LOW POPS ACROSS THE SOUTH FOR FIRST PART OF THE WEEKEND...BUT WILL CONTINUE TO LEAN TOWARD MODEL CONSENSUS WITH A DRY SATURDAY WITH EXPECTATION MORE FAVORED PRECIP CHANCES WILL BE SOUTH OF THE AREA. NO CHANGES TO REMAINDER OF EXTENDED WITH BEST CHANCE OF MCS DEVELOPMENT LIKELY REMAINING SOUTH OF THE AREA GIVEN LITTLE CHANGE IN LARGE SCALE WESTERN RIDGE/EASTERN TROUGH PATTERN AND SFC BOUNDARY SOUTH OF THE AREA. MARSILI && .AVIATION... 1252 AM CDT FOR 06Z TAFS...TRANQUIL WEATHER EXPECTED FOR THIS 24 HOUR FORECAST PERIOD WITH MAIN FOCUS ON WIND/LAKE BREEZE. LATE EVENING WATER VAPOR IMAGERY DEPICTS UPPER TROUGH OVER GREAT LAKES WITH A COUPLE OF MINOR SHORT WAVES ROTATING THROUGH WEST SIDE OF THIS FEATURE ACROSS WI/LAKE MICHIGAN. GENERALLY CLEAR SKIES OBSERVED ACROSS THE REGION HOWEVER...WITH UPSTREAM RAOBS DEPICTING RELATIVELY DRY MOISTURE PROFILES IN NORTHERLY FLOW. WITH THAT SAID...THERE HAS BEEN FEW/SCT MVFR STRATOCU OBSERVED NEAR LAKE MICHIGAN DURING THE LAST FEW HOURS...LIKELY AIDED BY LOW LEVEL CONVERGENCE ALONG WEST/SOUTH SHORE. NAM FORECAST SOUNDINGS OUT OVER THE WATER DO DEPICT A SHALLOW LAYER OF STEEPER LAPSE RATES OFF THE SURFACE FOR A TIME OVERNIGHT...THOUGH GRADUAL DIMINISHING TREND IN LOW LEVEL WIND FIELD AND WEAK COOL ADVECTION SHOULD KEEP A CEILING FROM DEVELOPING. WILL INCLUDE MENTION OF FEW AT 2000 FT FOR KORD/KMDW TERMINALS OVERNIGHT...THOUGH WOULD EXPECT THESE CLOUDS MAINLY CLOSER TO LAKE AND INTO SE CHICAGO/NW INDIANA IMMEDIATELY DOWNSTREAM OF LAKE. SHORT RANGE MODEL GUIDANCE INDICATES SHORT WAVE OVER WI SLIDES SOUTHEAST EARLY THIS MORNING...WITH TIME/HEIGHT SECTIONS SHOWING INCREASING DEEP SUBSIDENCE ACROSS THE FORECAST AREA THROUGH THE MORNING. FORECAST SOUNDINGS SUGGEST LITTLE/FEW DIURNAL CU DEVELOPING TODAY...WITH VFR BASES IN 5-6 KFT RANGE IF THEY DO. CLEAR SKIES EXPECTED TONIGHT WITH PERHAPS A LITTLE HIGH CIRRUS ALONG ANTICYCLONIC SHEAR SIDE OF UPPER JET. HAVE INCLUDED MENTION OF TEMPO FOR DIURNAL MVFR FOG AT KRFD EARLY THIS MORNING...WHERE RECENT ACARS VAPOR TRACE INDICATES MOISTURE IN LOWEST 800-1000 FT AND WINDS HAVE GONE CALM UNDER CLEAR SKIES. AS FOR WINDS...SURFACE HIGH GRADUALLY BUILDING SOUTH ACROSS UPPER MISSISSIPPI VALLEY/WESTERN LAKES REGION TODAY WITH LIGHT NORTH GRADIENT. SHOULD SEE LIGHT NORTHWEST LAND BREEZE COMPONENT DEVELOP THROUGH SUNRISE FOR KORD/KMDW WHILE WINDS BECOME LGT/VRBL FARTHER INLAND. GRADIENT NORTH/NORTHEAST WINDS AROUND 10 KNOTS TODAY SHOULD ALLOW MORE NORTHEASTERLY LAKE PUSH TO DEVELOP THIS AFTERNOON. SURFACE RIDGE THEN ACROSS NORTHERN IL TONIGHT SHOULD ALLOW WINDS TO GO VRBL/CALM LATER THIS EVENING. RATZER && .MARINE... 306 AM CDT HIGH PRESSURE OVER ONTARIO AND THE UPPER MIDWEST WILL CONTINUE TO MOVE SOUTH THROUGH THE WESTERN GREAT LAKES REGION TODAY...AND INTO THE OHIO VALLEY BY THURSDAY. AS THIS OCCURS...THE SURFACE PRESSURE GRADIENT ACROSS LAKE MICHIGAN WILL WEAKEN...ALLOWING NORTH WINDS TO DIMINISH THROUGH TODAY...AND EVENTUALLY BACK TO THE SOUTHWEST FOR THURSDAY. LOW PRESSURE MOVING ACROSS MANITOBA AND ONTARIO ON FRIDAY WILL TRAIL A COLD FRONT THROUGH THE UPPER MISSISSIPPI VALLEY AND CENTRAL PLAINS FRIDAY...AND ACROSS THE WESTERN GREAT LAKES REGION FRIDAY NIGHT. THIS FRONT WILL CONTINUE TO DROP INTO THE OHIO VALLEY SATURDAY AND SUNDAY...AS WEAK HIGH PRESSURE DEVELOPS ACROSS THE UPPER MIDWEST. FOR THE ILLINOIS AND INDIANA NEARSHORE AREAS...WINDS CONTINUE TO GUST IN THE 15 TO 20 KNOT RANGE EARLY THIS MORNING...ESPECIALLY ALONG THE SOUTH/SOUTHEAST SHORE AREAS. WITH A LONG NORTH FETCH FOR THE PAST 24-36 HOURS THIS WILL KEEP 5 TO 6 FOOT WAVES ALONG THE SOUTH SHORE EARLY TODAY...BEFORE DIMINISHING WINDS LATER TODAY ALLOW WAVES TO SLOWLY SUBSIDE. FOR THIS REASON...A SMALL CRAFT ADVISORY REMAINS IN EFFECT THIS MORNING. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY UNTIL 10 AM CDT THIS MORNING FOR LMZ740- LMZ741-LMZ742-LMZ743-LMZ744-LMZ745. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 1157 PM CDT TUE JUL 22 2008 .UPDATE... UPDATED FOR 06 UTC AVIATION. && .DISCUSSION... SEE PREVIOUS DISCUSSION. && .AVIATION... WARM AIR ADVECTION INTO TONGUE OF LOW LEVEL MOISTURE MAY BRING A FEW SHOWERS AND STORMS TO THE AREA OVERNIGHT...BUT SHOULD REMAIN ISOLATED AND NOT WORTHY OF TAF MENTION. THIS MOISTURE WILL BRING SOME CONCERN FOR LOWERED VISIBILITIES BUT BELIEVE WIND SPEEDS NEAR THE BOUNDARY LAYER WILL BE ENOUGH OF KEEP THEM AT VFR LEVELS. CONVECTIVE THREAT NOT ZERO FOR WEDNESDAY AFTERNOON/EVENING BUT WELL TO LOW FOR INCLUSION AT THIS POINT. && .PREV DISCUSSION... /ISSUED 344 PM CDT TUE JUL 22 2008/ DISCUSSION... WEAK SURFACE BOUNDARY JUST SOUTH OF I70 AT 20Z. MESOANALYSES SHOW SOME SURFACE CONVERGENCE ALONG BOUNDARY...AND WEAK CAP. DEWPOINTS HAVE POOLED JUST NORTH OF FRONT...WITH MIXED LAYER CAPES NEAR 4000 J/KG. HOWEVER...NO SIGNIFICANT CONVECTION HAS FIRED AND NOTHING APPEARS IMMINENT ON SATELLITE IMAGERY. RUC ANALYSIS AND PROFILER WINDS SHOWS WEAK VORT MAX OVER ERN NEBRASKA MOVING SE. HOWEVER...SUBSIDENCE IN WAKE OF THIS MORNINGS MISSOURI MCS HAS HELPED WITH OVERALL CONVECTIVE SUPPRESSION. WITH BOUNDARY REMAINING IN AREA...EXPECT ISOLATED CONVECTION TO STILL BE POSSIBLE TONIGHT INTO WEDNESDAY AS WEAK POSITIVE 850 MB THETA-E ADVECTION CONTINUES. POPS KEPT AOB 20 PERCENT TONIGHT AND WEDNESDAY. RELATIVELY HIGH DEWPOINTS ACROSS ERN KS SHOULD KEEP LOW TEMPS IN THE UPPER 60S TO LOWER 70S. ON WEDNESDAY...GFS MOS GUIDANCE WARMER THAN NAM OR NGM AND HAVE GONE CLOSER TO THIS BASED ON RECENT PERFORMANCE. PHILLIPS WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...THE UPPER RIDGE WILL AMPLIFY ACROSS THE SOUTHERN PLAINS WHILE AN UPPER LEVEL TROUGH MOVES EAST ACROSS THE NORTHERN PLAINS INTO THE UPPER MIDWEST. WEDNESDAY NIGHT INTO THURSDAY MORNING THERE MAY BE A SLIGHT CHANCE FOR ELEVATED SHOWERS AND THUNDERSTORMS TO DEVELOP AS WAA/ISENTROPIC LIFT INCREASES ACROSS THE NORTHERN AND EASTERN PORTIONS OF THE CWA...BUT BEING UNDER THE 5H RIDGE AXIS MAY INHIBIT THE DEVELOPMENT OF ELEVATED THUNDERSTORMS. AS THE 5H TROUGH MOVES ACROSS THE NORTHERN HIGH PLAINS THEN DIGS SOUTHEAST INTO THE GREAT LAKES...A WEAK COLD FRONT WILL MOVE SOUTHWARD ACROSS NE AND INTO NORTH CENTRAL KS DURING THE AFTERNOON HOURS. THERE MAY BE ENOUGH SFC CONVERGENCE FOR ISOLATED THUNDERSTORMS TO DEVELOP THURSDAY AFTERNOON ACROSS THE NORTH CENTRAL KANSAS ALONG THE COLD FRONT. HIGHS ON THURSDAY MAY BE CLOSE TO 100 DEGREES ACROSS THE SOUTHWEST AND WEST CENTRAL CWA...WITH LOWER 90S ACROSS THE NORTHEAST COUNTIES OF THE CWA. THE FRONT WILL MOVE SOUTHEAST ACROSS THE NORTHERN AND EASTERN CWA PROVIDING AT LEAST A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS THURSDAY NIGHT. FRIDAY THROUGH SATURDAY NIGHT...THE WEAK FRONT WILL MOVE SOUTHWARD AND STALL OUT AND WEAKEN ALONG I-70. THE 5H TROUGH OVER THE MIDWEST WILL DIG SOUTHEAST INTO THE GREAT LAKES STATES. BOTH THE ECMWF AND GFS SHOW THE SOUTHERN PLAINS 5H RIDGE RE-AMPLIFYING. SYNOPTIC SCALE SUBSIDENCE UNDER THE 5H RIDGE SHOULD CREATE AN ENVIRONMENT UNFAVORABLE FOR DEEP MOIST CONVECTION...BUT I CANNOT RULE OUT PULSE STORMS DEVELOPING ALONG OR NORTH OF THE BOUNDARY DURING THE LATE AFTERNOON HOURS FRIDAY...GIVEN DEEP MOISTURE AND STRONG SFC HEATING. THEREFORE...I KEPT A 14 POP DURING THE DAY FRIDAY AND 15 POPS FRIDAY EVENING. TEMPERATURES ACROSS THE NORTHERN COUNTIES MAY ONLY REACH THE LOWER TO MID 90S NORTH OF THE WEAK SFC BOUNDARY. SOUTH OF THE SFC BOUNDARY HIGHS WILL BE IN THE UPPER 90S...POSSIBLY NEAR 100 DEGREES OVER THE SOUTHERN COUNTIES OF THE CWA. ON SATURDAY BOTH THE ECMWF AND GFS SHOW THE 5H RIDGE AXIS RETROGRADING INTO THE WEST CENTRAL CONUS AS A LONGER WAVE LENGTH 5H TROUGH OVER THE EASTERN CONUS AMPLIFIES. HIGH TEMPERATURES MAY BE A FEW DEGREES COOLER AS THE CENTER OF THE RIDGE AXIS SHIFTS WEST OF THE SOUTHERN PLAINS. HIGHS ON SATURDAY WILL BE IN THE MID 90S ACROSS MOST OF THE CWA. SATURDAY NIGHT THROUGH TUESDAY...BOTH THE ECMWF AND GFS KEEP A LONGER WAVE LENGTH 5H TROUGH ACROSS THE EASTERN CONUS AND A BROAD 5H RIDGE ACROSS THE WEST CENTRAL CONUS. THE ECMWF IS A BIT MORE AMPLIFIED WITH THE 5H TROUGH OVER THE EASTERN CONUS...AND BRINGS A COLD FRONT SOUTHWESTWARD INTO THE CWA SUNDAY INTO MONDAY. THIS WOULD PROVIDE THE CWA WITH A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS SATURDAY NIGHT THROUGH SUNDAY NIGHT. HOWEVER...THE GFS IS NOT AS AMPLIFIED WITH THE EASTERN CONUS 5H TROUGH AND KEEPS THE FRONT NEARLY STATIONARY ACROSS EASTERN NE...SOUTHEAST INTO WESTERN MO. IF THE GFS WERE TO VERIFY THE BEST RAIN CHANCES WILL REMAIN NORTH AND EAST OF THE CWA. THEREFORE...I PLACED IN SLIGHT CHANCES FOR THUNDERSTORMS SATURDAY NIGHT THROUGH SUNDAY NIGHT ACROSS THE CWA. THE ECMWF MODEL FORECAST SHOWS THE FRONT MOVING SOUTHWARD INTO NORTHERN OK MONDAY AND TUESDAY...AND THE GFS MODEL SOLUTION KEEPS THE FRONT NORTHEAST OF THE CWA...THEREFORE I KEPT POPS AT 14 PERCENT MONDAY NIGHT AND TUESDAY. HIGHS SUNDAY THROUGH TUESDAY WILL ONLY REACH THE LOWER TO MID 90S...SINCE THE 5H RIDGE AXIS WILL SHIFT FARTHER WEST. HIGH MAY BE A BIT COOLER ON SUNDAY AND MONDAY IF THE ECMWF SOLUTION WERE TO VERIFY BRING THE SFC COLD FRONT SOUTHWEST ACROSS THE CWA. GARGAN && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ 65 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 334 AM CDT WED JUL 23 2008 .DISCUSSION... RADARS EARLY THIS MORNING INDICATED A TSTM CLUSTER MOVING SEWD THROUGH THE MO OZARK FOOTHILLS REGION NEAR AN 850 MB WIND CONVERGENCE BOUNDARY. THE RUC MODEL SHOWS THIS PATTERN DISAPPEARING BY 12Z OR SO...AS DRIER AIR FILTERS IN ON THE NOSE OF A SFC HIGH PRESSURE AREA. THIS SHOULD ALL BUT ELIMINATE CHCS OF PCPN BY AFTN EVEN NEAR THE AR/TN BORDER. THE PAH FCST AREA WILL BE RAIN FREE THROUGH THU AFTN...THEN THE MID LEVEL FLOW OVER OUR REGION IS PROGGED TO TAKE ON A MORE WRLY COMPONENT AS AN ERN GREAT LAKES LOW DEPARTS INTO CANADA. THIS SHOULD RESULT IN THE EWD EXPANSION OF THE SWRN CONUS MID LEVEL RIDGE AND THE REINTRODUCTION OF WARM MOIST AIR FROM THE SW ON THU NIGHT/FRI. SCT SHWS/TSTMS WILL PROBABLY RESULT IN THE VICINITY OF THE WARM FRONT. FRI NIGHT PCPN CHCS WILL DECREASE SOME... ESPECIALLY IN SERN MO AS SHRTWV ENERGY EVENTUALLY TURNS LOW LEVEL WINDS BACK TO THE NORTH...TENDING TO DRY OUT THE ATMOSPHERIC COLUMN. THIS WRN RIDGE/ERN TROF PATTERN IS EXPECTED TO CONTINUE...WITH AN ON AND OFF PCPN PATTERN LASTING AT LEAST THROUGH THE WEEKEND AS SHRTWV ENERGY IMPULSES MOVE THROUGH THE NWLY MID LEVEL PATTERN. ALL IN ALL...POPS ARE NOT VERY HIGH. FURTHER INTO NEXT WEEK...MODELS ARE IN GOOD AGREEMENT THAT DRIER NWRLY FLOW APPEARS TO WIN OUT FOR MUCH OF THE WEEK. TEMPS WILL BE MODERATE FOR THIS TIME OF YEAR. && .AVIATION... CONVECTION SHOULD STAY WEST OF THE TAF SITES EARLY TODAY. SOME MID CLOUDS MAY AFFECT THE SITES EARLY ON...FOLLOWED BY A CHANCE OF CU FORMATION. WINDS WILL BE LIGHT NE DURING THE DAY...NEARLY CALM AT NIGHT. SOME BRIEF VSBYS 3-5SM CANNOT BE RULED OUT EARLY THIS MORNING. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ PUBLIC....DB AVIATION...CN ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 410 AM CDT WED JUL 23 2008 .SHORT TERM...TODAY THROUGH FRIDAY MAIN FCST CHALLENGE IN THE SHORT TERM DEALS WITH PCPN CHANCES THROUGH THE PERIOD. CURRENTLY ONGOING MCS LOCATED ACROSS ERN MT/WRN ND...WITH MORE ACCAS TYPE TSRA DEVELOPING IN LLJ REGION OF WRN SD...WITH IR TOPS INDICATING SOME COOLING TAKING PLACE ACROSS SWRN SD. RUC HAS THIS PCPN HANDLED FAIRLY WELL...WITH PCPN ADVECTION MOVING EAST/JUST NORTH OF EAST THROUGH THE REMAINDER OF THE MORNING. HAVE INCLUDED SOME LIKELY POPS FOR THE MORNING HOURS ACROSS SECTIONS OF THE NW CWA TO HANDLE CONVECTION THAT IS CURRENTLY ON GOING/EXPECTED TO DEVELOP. ATTENTION THEN TURNS TOWARD LATER THIS AFTERNOON/THIS EVENING FOR CONVECTIVE CHANCES. MODELS AGREE ON 7H TROF/WAVE COMBO TO IMPACT CWA LATER THIS AFTERNOON...WITH VERY SLOW MOVT EXPECTED WITH 7H TROF. BY 00Z THURSDAY...BOTH GFS/NAM SHOW SHOW QUITE A BIT OF 85H- 7H FRONTOGENESIS TAKING PLACE ACROSS THE MO RIVER REGION...ALONG WITH SPEC HUMIDITIES AOA 10G/KG. 7H TEMPS MAY BE JUST HIGH ENOUGH TO KEEP ATMOS CAPPED THROUGH 21/22Z BEFORE ALLOWING RAPID CONVECTIVE DEVELOPMENT. THE MAIN UNCERTAINITY IN THIS IS THE SKY COVER. CURRENT MCS SHIELD OVERSPREADING CWA...AND THIS MAY BE ENOUGH TO HELP INHIBIT SOME DEVELOPMENT. THINK THAT THE WRN PART OF THE CWA WILL CLEAR OUT ENOUGH LATER THIS AFTN FOR RAPID DESTABILIZATION TO TAKE PLACE. ALSO...NOTICED THAT LOW LEVEL TRAJECTORIES TURN MORE SOUTHERLY AHEAD OF EXPECTED SFC TROF...WHICH SHOULD ALSO ALLOW MORE LOLEVEL MOISTURE TO STREAM NORTHWARD. NOTICED THAT DWPTS ACROSS SC NEB AT 08Z WERE IN THE LOWER 70S. GFS HAS PWATS APPROACHING 2 INCHES BY 00Z TONIGHT. STEERING FLOW LOOKS TO BE SUFFICIENT TO PREVENT A LARGE RESIDENCE TIME...SO NO PLANS ON ANY HEAVY RAIN HEADLINES ATTM...BUT LOCALLY HEAVY RAIN IS GOING TO BE POSSIBLE...SO WILL COVER IN THE HWO. WITH WRN PART OF THE CWA ALSO EXPECTED TO CLEAR...WILL COVER PSBL SEVERE IN THE HWO. 7H TROF IS SLOW TO MOVE EAST...SO MECHANISM WILL RESET A BIT FOR THURSDAY...ALTHO HIGHER AXIS OF PWATS DO SHIFT A BIT MORE SOUTH AND EAST. CONCERN IS THAT BOTH NAM/GFS HIGHLIGHT SFC LOW MOVING SLOWLY THROUGH DURING THE DAY. OVERNIGHT CONVECTION LEAVES ERN CWA THURSDAY MORNING...WITH ANOTHER ROUND OF CONVECTION DEVELOPING IN POST FROPA INSTABILITY AXIS WITH NEXT 7H WAVE IMPACTING SLOW MOVING FEATURE. HAVE ADDED IN SOME SLIGHT CHC POPS FOR THURSDAY AFTN...AND THESE WILL NEED TO BE REVISITED DURING LATER SHIFTS TO SEE IF THURSDAY AFTN INSTABILITY DOES INDEED DEVELOP. TEMP WISE...HAVE STUCK PRETTY CLOSE TO INHERITED GRIDS AS TEMPS WILL BE HIGHLY DEPENDANT UPON THE AMOUNT OF CLEARING THAT TAKES PLACE COUPLED WITH HOW MUCH MOISTURE DOES ADVECT NORTHWARD. .LONG TERM...FRIDAY NIGHT THROUGH TUESDAY THE BEST CHANCES FOR THUNDER STILL RESIDE ACROSS THE WESTERN HALF OF FORECAST ZONES...SATURDAY NIGHT AND THEN AGAIN MONDAY AND MONDAY NIGHT...PER THE LATEST 12Z/00Z GFS/EC OPERATIONAL SOLUTIONS. BOTH OF THESE MODELS ARE IN FAIR AGREEMENT ALOFT THROUGH APPX 96 HOURS...BEFORE BEGINNING TO DIVERGE ON TIMING/AMPLITUDE OF MID/UPPER LEVEL TROF/RIDGE AXES OVER THE LOWER 48. BOTH MODELS HINT AT SHORTWAVE TROFPAS SATURDAY NIGHT AND AGAIN SOMEWHERE IN THAT MONDAY/MONDAY NIGHT TIMEFRAME. NO NOTABLE CHANGES MADE TO FRIDAY NIGHT THROUGH SUNDAY AFTERNOON PORTION OF THE EXTENDED WITH THE MORNING FORECAST PACKAGE. && .AVIATION... 06Z TAFS FOR KABR...KATY...KPIR AND KMBG VFR PARTLY TO MOSTLY CLOUDY SKIES WITH UNRESTRICTED VISBYS PREVAIL THROUGH TODAY. CIGS WILL REMAIN MAINLY AT OR ABOVE 5000FT AGL THROUGHOUT THE TAF VALID PERIOD. AN AREA OF LOW PRESSURE WILL MOVE THROUGH THE REGION FROM THE WEST TODAY AND TONIGHT RESULTING IN SCATTERED SHOWERS AND THUNDERSTORMS THIS MORNING MOVING ACROSS THE KPIR AND KMBG TERMINALS. BETWEEN 15Z AND 21Z TODAY...THE MAIN THREAT FOR THUNDER IS SHIFTING EAST TO IMPACT THE KABR AND KATY TERMINALS. THESE SHOWERS AND STORMS WILL BE RATHER EFFICIENT AT PRODUCING HEAVY RAIN...SO ANTICIPATE IFR CIG/VISBY REDUCTIONS UNDERNEATH THESE STORMS THIS AFTERNOON. THEN...FROM 00Z TO 06Z TONIGHT...THE FOCUS FOR POTENTIAL THUNDERSTORM REDEVELOPMENT WILL BACK-PEDDLE TO THE WEST...AGAIN WITH THE KPIR AND KMBG TERMINALS MAINTAINING THE GREATEST POTENTIAL TO SEE THUNDERSTORMS RUMBLE THROUGH TERMINAL AIRSPACE DURING THE EVENING HOURS. THESE EVENING THUNDERSTORMS WILL BE CAPABLE OF PRODUCING LARGE HAIL AND DAMAGING THUNDERSTORM WIND GUSTS. WILL WHITTLE DOWN TSRA MENTION IN THE TAFS AS THUNDERSTORM EVENT TIMES GROW CLOSER...STARTING OUT THIS MORNING MAINLY WITH CB MENTION AND/OR VCTS AS WARRANTED...UPDATING WITH TSRA MENTION IN THE NEARER TERM AS APPROPRIATE. SURFACE WINDS SHOULD MAINTAIN A SOUTH-SOUTHEASTERLY DIRECTION AND BREEZY FOR MUCH OF THE TAF VALID PERIOD. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ SHORT TERM...HINTZ LONG TERM...DORN AVIATION...DORN WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 728 AM EDT WED JUL 23 2008 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SLOWLY DEPARTING UPR TROF OVER SE ONTARIO DOWNSTREAM OF HI AMPLITUDE RDG EXTENDING FM THE PLAINS INTO SCNTRL CAN. AT THE SFC/H85...SPRAWLING HI PRES CENTERED OVER NRN ONTARIO. BACK EDGE OF DEEPER MSTR ASSOCIATED WITH THE TROF IS IN ERN UPR MI WITH LINGERING SCT-BKN MID CLD. TO THE W AND NW...00Z INL/YPL RAOBS ARE QUITE DRY/STABLE WITH PWAT JUST A BIT OVER 0.50 INCH/WELL DEFINED CAP ARND H7 ABV WELL MIXED PBL. AFTN DIURNAL CU IN THESE AREAS YDAY GAVE WAY TO MOCLR SKIES DURING THE EVNG. MAIN FCST CONCERNS INTO THU REVOLVE ARND TEMPS WITH ONTARIO HI PRES/ DRY AIRMASS FCST TO DOMINATE. FOCUS FOR THU NGT THRU FRI NGT SHIFTS TO TIMING/IMPACT OF TROF NOW IN THE PAC NW TO THE W OF UPR RDG IN THE PLAINS. FOR TDAY/TNGT...DRY HI PRES FCST TO BLD OVER THE UPR GRT LKS AND TO NR MNM BY 12Z THU. ALTHOUGH THERE WL BE SCT DIURNAL CU OVER THE INTERIOR CWA THIS AFTN AWAY FM THE STABILIZING INFLUENCE OF THE GRT LKS...EXPECT MOCLR SKIES OTRW. THE ONLY OTHER EXCEPTION MAY BE OVER THE FAR ERN CWA TNGT...WHERE ANOTHER SHRTWV ROTATING ARND NRLY STNRY CLOSED LO THE E MAY BRING SOME CLD IN TNGT. DRY AIRMASS SUGS A WIDE DIURNAL VARIATION IN TEMP BTWN THIS AFTN/TNGT. WITH H85 TEMPS FCST ARND 12C BY 00Z THU...EXPECT HI TEMPS TO APRCH 80 AWAY FM LK COOLING MOST PRONOUNCED DOWNWIND OF LK SUP AND THE BAY OF GREEN BAY S OF ESC WITH NLY H925 FLOW MINIMIZING LK MI INFLUENCE AT AREAS E OF ESC. MIXING TO H75-8 TDAY WOULD SUG SFC DWPTS WL FALL INTO THE MID 40S PER 00Z INL RAOB/GFS FCST SDNGS...RESULTING IN MIN RH FALLING AOB 30 PCT OVER THE INTERIOR. ALTHOUGH DVLPG RETURN SSW FLOW LATE TNGT MAY TEND TO BRAKE FALL OF TEMP OVER THE FAR W AT IWD- ONTONAGON...WL GO BLO MOS GUIDANCE OVER MOST OF THE INTERIOR TO THE E WITH PROMISE OF LGT WINDS/CLR SKIES. STUBBORN UPR LO IN ONTARIO IS PROGGED TO LIFT SLOWLY TO THE NE ON THU...BUT LARGER SCALE ACYC FLOW IS PROGGED TO LINGER UNDER RDG AXIS JUST TO THE NW THAT WL BE WEAKENING AS PAC NW TROF PRESSES INTO SCNTRL CAN. ANTECEDENT DRY AIRMASS...PERSISTENCE OF RDGING/ACYC FLOW UPSTREAM OF STUBBORN BLOCK TO THE E...AND INTERCEPTION OF RETURNING DEEPER MSTR CLOSER TO WARM FNT WELL TO THE S WOULD SUG DRY...CAPPED NAM IS ON THE RIGHT TRACK AND GFS IS TOO AGGRESSIVE AT GENERATING PCPN OVER THE WRN ZNS IN THE AFTN. BUT WL RETAIN GOING LO CHC POPS TO ACCOUNT FOR GFS FCST AND RATHER HI ETA MOS POP AS WELL FOR IWD. DESPITE SOME INCRS IN CLD COVER...TEMPS WL BE AOA EXPECTED MAX TEMPS FOR TDAY WITH H85 TEMPS A DEGREE OR TWO WARMER AND RETURN SW FLOW MINIMIZING LK SUP COOLING. THE EXCEPTION WL BE ALONG/DOWNWIND OF THE LK MI SHORE. AS INCOMING UPR TROF ACRS SRN CAN BREAKS DOWN RDG A BIT MORE THU NGT...ASSOCIATED SFC COLD FNT IS PROGGED TO ARPCH WRN LK SUP BY 12Z FRI...GFS A BIT FASTER THAN NAM. PER NCEP GUIDANCE...FOLLOWED COMPROMISE 00Z UKMET/12Z ECMWF FOR TIMING...WHICH SHOW THE BNDRY REACHING THE MN/LK SUP AT 12Z FRI. SINCE SHARP WARM FNT REMAINS WELL TO THE SW...MSTR INFLOW WL BE LIMITED...AND MODEL QPFS ARE RATHER MODEST. 12Z ECMWF IS A BIT MORE AGGRESSIVE THAN THE 00Z UKMET WITH HGT FALLS/DPVA/DEEP LYR QVECTOR CNVGC ASSOCIATED WITH INCOMING TROF...ESPECIALLY OVER WRN UPR MI. WL THUS CARRY A 30 POP OVER THE NW BUT KEEP THE ERN ZNS DRY SO FAR E OF THE INCOMING BNDRY AT DIURNAL MIN HTG TIME. ECMWF/UKMET SHOW SSI ARND +4C AT ERY THRU THE NGT...AND NAM FCST SDNGS ARE QUITE DRY IN THE MID LVLS. BULK OF NUMERICAL GUIDANCE SHOWS COLD FNT REACHING THE SCNTRL AND E LATE IN THE DAY ON FRI. PCPN CHCS ON FRI WL BE LIMITED BY WEAK LLVL CNVGC ALG THE FNT...LIMITED MSTR INFLOW...AND QUITE A BIT OF DRY MID LVL AIR. ON THE OTHER HAND...LACK OF CLD COVER WOULD SUG A GOOD DEAL OF INSOLATION/DESTABILIZATION. PLACEMENT OF FA IN LEFT EXIT OF JET MAX SUPPORTING INCOMING TROF SHOWN MOST BY 12Z ECMWF ALG WITH SOME FAIRLY SHARP DVPA/DEEP LYR QVECTOR CNVGC WOULD ADD LARGER SCALE LIFT. BUT THE 00Z GFS/UKMET SHY AWAY FM THIS STRONGER JET SCENARIO... SO OPTED TO REDUCE POPS A BIT TO NO MORE THAN 30 EXCEPT OVER THE FAR SCNTRL AND E WHERE LATER ARRIVAL OF FNT WL BE MOST IN SYNC WITH DIURNAL HTG CYCLE AND SOME LK BREEZE CNVGC. GOING 40 POP SEEMS APPROPRIATE THERE. TENDED TOWARD THE HI END OF MOS GUIDANCE FOR MAX TEMPS EXCEPT OVER THE W DOWNWIND OF LK SUP/NEAR LK MI WITH DOWNSLOPING WNW FLOW/EXPECTED DECENT AMT OF SUNSHINE. INCRSG UNIDIRECTIONAL WINDS IN THE LO/MID TROP (0-6KM BULK SHEAR FCST TO INCRS TO 40 KTS) AND PRESENCE OF DRY MID LVL AIR WOULD SUG A RISK FOR SOME SVR STORMS. MODIFIED GFS FCST SDNG FOR MNM FOR SFC T/TD 83/60 AND SOMEWHAT COOLER MID LVL TEMPS TO ACCOUNT FOR POTENTIAL OF STRONGER JET DYNAMICS THAN EXPLICITLY FCST BY 00Z GFS YIELDS SB CAPE ARND 930 J/KG. BUT LAPSE RATES...EVEN WITH A DEGREE OR SO OF MID LVL COOLING...DO NOT APPEAR PARTICULARLY STEEP. SINCE SPC DOES NOT HAVE UPR GRT LKS OUTLOOKED FOR MENTION OF SVR STORMS...WL LEAVE OUT MENTION FOR NOW. WITH LOSS OF DIURNAL HTG FRI NGT AND FAIRLY STRONG MID LVL DRYING IN WAKE OF COLD FROPA...TENDED TO END POPS FASTER W-E THAN PREVIOUS FCST. BUT MAINTAINED LO CHC POPS OVER LK SUP THRU THE NGT AND INTO SAT CLOSER TO DIGGING SHRTWV THRU ONTARIO AND SOMEWHAT DEEPER MSTR. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... VFR CONDITIONS WILL PREVAIL THROUGH THIS FORECAST PERIOD WITH DRY HIGH PRESSURE BUILDING OVER THE AREA. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... THE HIGH PRESSURE OVER THE UPPER GREAT LAKES WILL KEEP WINDS LESS THAN 15 KNOTS THROUGH THURSDAY. AS THIS HIGH DRIFTS EAST ON FRIDAY...A LOW PRESSURE TROUGH WILL MOVE INTO THE UPPER GREAT LAKES CAUSING SOUTHERLY WINDS TO INCREASE AND VEER TO THE WEST. AS THIS TROUGH DRIFTS INTO THE CENTRAL GREAT LAKES ON SATURDAY...THE WINDS WILL SHIFT NORTHWEST AGAIN. OTHERWISE...WINDS WILL BE NO GREATER THAN 20 KNOTS THIS WEEK END. WAVES WILL STILL REMAIN 3 FEET OR LESS THROUGH THE PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...KC AVIATION...DLG MARINE...DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 1007 AM CDT WED JUL 23 2008 .UPDATE... INCREASED SKY COVER MAINLY IN THE WESTERN CWA. REST OF THE FORECAST MOSTLY UNCHANGED. && .DISCUSSION... CIRRUS BLOWOFF FROM THUNDERSTORMS IN THE DAKOTAS WILL FIGHT AGAINST STRONG RIDGE OVER THE CWA TODAY. LATEST IR IMAGERY SHOWS CLOUD TOP TEMPERATURES WARMING IN THE DAKOTAS...AND LIGHTNING ACTIVITY IS DIMINISHING...INDICATING THESE STORMS ARE WEAKENING. VISIBLE SATELLITE IMAGERY DEPICTS SOME OF THE CIRRUS IS INVADING THE WESTERN CWA. LATEST NAM/RUC GUIDANCE INDICATES THIS CLOUD COVER WILL MAKE SOME EASTERN PROGRESSION THIS AFTERNOON FROM WESTERN MN...BUT MUCH OF THE CLOUD COVER WILL BREAK UP AS IT HITS THE RIDGE. CLOUD COVER WILL INCREASE OVERNIGHT AS THE RIDGE SLIDES EAST. FORECAST ATTENTION WILL SHIFT TO POTENTIAL CONVECTIVE ACTIVITY OVERNIGHT. && .PREV DISCUSSION... /ISSUED 315 AM CDT WED JUL 23 2008/ DISCUSSION...MAIN FORECAST FOCUS IS CONVECTIVE CHANCES FOR LATE TONIGHT THROUGH THURSDAY NIGHT. EARLY MORNING SURFACE ANALYSIS SHOWS HIGH PRESSURE CENTERED OVER NW ONTARIO...WITH AXIS STRETCHING ACROSS EASTERN DLH FA. QUIET DAY ON TAP FOR THE NORTHLAND...WITH LARGE SCALE SUBSIDENCE AS UPPER RIDGE NUDGES OVERHEAD. WILL ALSO SEE SOME WEAK WAA TODAY...AS SOUTHERLY WINDS INCREASE BEHIND DEPARTING HIGH PRESSURE. FORECAST SOUNDINGS SHOW DRY AIRMASS IN PLACE FOR TODAY...WITH JUST SOME CIRRUS MOVING OVERHEAD THIS AFTERNOON FROM THE STORM SYSTEM TO THE WEST. HIGH TEMPERATURES WILL BE SEASONABLE TODAY...EXCEPT FOR EXPECTED LAKE BREEZE...KEEPING COOLER TEMPS LAKESIDE. TONIGHT...RETURN FLOW WILL INCREASE AS SHORT WAVE APPROACHES FROM THE WEST. SOME TIMING DIFFERENCES IN THE MODELS WITH THIS WAVE...BUT LOOKS LIKE SCT CONV SHOULD PUSH INTO THE WESTERN ZONES LATE TONIGHT AS 30KT LLJ VEERS. LIMITED MOISTURE RETURN AND WEAK INSTABILITY SHOULD HINDER WIDESPREAD STRONG CONVECTION WITH THIS WAVE AS IT PUSHES SLOWLY EAST THROUGH THURSDAY. THEREFORE MAINTAINED LOW CHANCE POPS ATTM. THURSDAY NIGHT AND FRIDAY...WILL SEE ANOTHER SHORT WAVE DIVE SOUTHEAST AS UPPER FLOW PATTERN BECOMES MORE NORTHWESTERLY...AND SECONDARY COLD FRONT PUSHES THROUGH THE FA. NARROW AXIS OF INSTABILITY AND SUFFICIENT DEEP LAYER SHEAR SHOULD RESULT IN ISOLD TO SCT CONVECTION WITH THIS SHORT WAVE AS WELL. FOR THIS WEEKEND...DRIER CONDITIONS WILL PREVAIL WITH NORTHWEST FLOW ALOFT. DRY HIGH PRESSURE WILL BUILD INTO THE REGION FRIDAY NIGHT AND CONTINUE TO INFLUENCE THE NORTHLAND WEATHER THROUGH MONDAY. TEMPERATURES LOOK TO REMAIN SEASONABLE THROUGH EARLY NEXT WEEK. AVIATION...AREAS OF RADIATIONAL FOG AND LOCAL MVFR/IFR CONDITIONS CAN BE EXPECTED THROUGH 12Z TODAY...OTHERWISE HIGH PRESSURE WILL BEGIN PUSHING EAST OF THE AREA TODAY...WITH VFR CONDITIONS PREVAILING THROUGH THIS EVENING. WHILE A FEW CUMULUS MAY DEVELOP...THE ENTIRE AREA WILL EXPERIENCE A GRADUAL INCREASE IN HIGH AND MID LEVEL CLOUDS WITH A RETURN FLOW AND MODEST WARM AIR ADVECTION IN ADVANCE OF AN APPROACHING SHORTWAVE. PRECIPITATION CHANCES WILL REMAIN WEST OF OUR REGION UNTIL AFTER 6Z THURSDAY. && POINT TEMPS/POPS... DLH 74 54 72 56 / 0 20 30 20 INL 80 56 79 58 / 10 30 30 20 BRD 81 61 80 62 / 10 30 30 20 HYR 80 48 79 61 / 0 10 30 20 ASX 77 49 74 59 / 0 10 30 20 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. $$ KD/DAP mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 1142 AM EDT WED JUL 23 2008 .SYNOPSIS... AN UNUSUALLY STRONG STORM SYSTEM FOR MID SUMMER WILL MOVE SOUTHEAST FROM THE GREAT LAKES REGION TODAY...DRAGGING A SLOW MOVING COLD FRONT ACROSS THE STATE. SEVERAL WAVES OF LOW PRESSURE RIDING NORTHWARD ALONG THE FRONT WILL BRING HEAVY RAINFALL OF 2 INCHES OR MORE TO PARTS OF EASTERN EASTERN PENNSYLVANIA TODAY AND TONIGHT. SLOW IMPROVEMENT WILL OCCUR THURSDAY AS HIGH PRESSURE BUILDS EAST INTO THE REGION. FRIDAY WILL BE WARM AND DRY. ANOTHER COLD FRONT WILL APPROACH THE REGION THIS WEEKEND WITH ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS ON SATURDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... CONVEYOR BELT OF RAIN CONTINUES TO FEED UP OVER ABOUT THE EASTERN HALF OF MY FCST AREA...WITH ONLY SLOW EASTWARD TRANSLATION TO THE BACK EDGE. FURTHER WEST UNDER THE RELATIVELY COOL CYCLONIC UPPER FLOW...INSTABILITY IS STARTING TO MAKE ITSELF KNOWN WITH A BROKEN LINE OF STORMS FROM WARREN COUNTY SOUTHWARD. ENSEMBLES AND OPERATIONAL MODELS CONTINUE TO PUSH THE IDEA THAT THE FURTHER ONE GOES IN THE STATE THE HIGHER THE THREAT FOR HEAVY RAIN WILL BE. THIS IS WHERE THE BEST PRECIP WATER/LOW LEVEL JET ANOMALIES FOCUS ALONG WITH THE STRONGEST LOW LEVEL MOISTURE FLUX CONVERGENCE. WATER VAPOR SHOWS STRONG DRYING DIVING INTO THE SRN OHIO VALLEY...TESTAMENT TO THE STRENGTH OF THE DIGGING UPPER TROUGH. THE RESULTANT UPPER JET ENTRANCE REGION IS FCST TO SHARPEN AND PIVOT AS IT SLIDES ONLY SLOWLY EASTWARD TODAY...SUPPORTING THE IDEA OF A FRONTOGENTIC REGION...AND SEVERAL WAVES OF LOW PRESSURE RIPPLING ALONG THE BOUNDARY. OPERATIONAL MODELS ARE NOT ANALYZING THE SORT OF FRONTOGENETIC FORCING THAT IS IMPLIED BY THE BANDED RADAR RETURNS AND WOULD BE EXPECTED UNDER THE STRONGLY ANTICYCLONICALLY CURVED UPPER JET ENTRANCE REGION. I IMAGINE EMBEDDED CONVECTION MAY BE TAKING ITS TOLL. REGARDLESS...THE SYSTEM HAS A MORE WINTER- LIKE LOOK AND FEEL TO IT THAN A SYSTEM NORMALLY SEEN AT THE HEIGHT OF SUMMER. FLASH FLOOD GUIDANCE REMAINS HIGH SO NO FLOOD WATCHES PLANNED AT THIS TIME...BUT SMALLER SCALE NUISANCE FLOODING CANNOT BE RULED OUT IN SOME OF THE LOCALLY HEAVY BANDS THAT MANAGE TO TRAIN ALONG FOR ANY AMOUNT OF TIME. WILL HANDLE THOSE WITH ADVISORIES AND STATEMENTS...FOR NOW. IF THINGS DO LOOK LIKE THEY HAVE THE POTENTIAL TO DETERIORATE...WOULD THINK THE HIGHEST THREAT AREA FOR A FLOOD WATCH WOULD BE EAST OF A LINE FROM ABOUT WILLIAMSPORT TO YORK. ALL OF CENTRAL PENN IS ONCE AGAIN IN SPC`S SLIGHT RISK AREA...HOWEVER INSTABILITY IS MEAGER GIVEN THE EXTENSIVE CLOUD COVER AND WIDESPREAD RAIN. RUC SHOWS HIGHEST CAPES OVER SERN AREAS WHERE DEWPOINTS ARE NEAR 70...AND ANOTHER MAX OF CAPE OVER THE FAR WEST WHERE SUNSHINE WAS MOST ABUNDANT EARLIER TODAY. WINDS ALOFT ARE NOT TERRIBLY IMPRESSIVE SO WE WOULD HAVE TO SEE SOME RELATIVELY POTENT CORES DEVELOP IN ORDER TO MANAGE ANY KIND OF SIGNIFICANT WIND GUSTS. THINK THE LIKELIHOOD OF THAT IS LOW. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... 03Z SREF PUSHES FRONTAL BOUNDARY SLOWLY THRU CENTRAL/EASTERN PA THIS AFTERNOON AND TONIGHT...AS AN AMPLIFYING UPPER TROF SWINGS THRU...TAKING ON A NEG TILT BY LATE IN THE DAY/EVENING. STRONG LARGE SCALE FORCING...FAVORABLE RIGHT ENTRANCE OF JET AND ANOMALOUS PWATS ALONG FRONT ALL POINT TOWARD THE POTENTIAL OF LOCALLY HVY CONVECTIVE RAINFALL ACROSS EASTERN PA INTO TONIGHT. CATEGORICAL POPS ACROSS THE SUSQ VALLEY (ALL NIGHT)...AND IN MOST OTHER AREAS AREAS EARLY...WILL BE TRIMMED CHC OR LIKELY ACROSS THE CENTRAL AND WEST AFTER MIDNIGHT. UPPER TROUGH DEEPENS TO -2 TO -3 STD DEVIATIONS OVERNIGHT...BEFORE SLOWLY FILLING AS IT DRIFTS ENE ACROSS PENN THURSDAY. 700 HPA TEMPS COOLING STEADILY TO SLIGHTLY BELOW ZERO ACROSS THE WRN HALF OF THE STATE BY 00Z FRIDAY WILL CREATE STEEP MID LEVEL LAPSE RATES ON THE ORDER OF NEARLY 7C/KM...ABUNDANT CLOUDS OR "SELF DESTRUCT" SUNSHINE...AND AT LEAST SCATTERED SHOWERS. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... DRIER AIR GRADUALLY WORKS INTO THE REGION FROM THE WEST THURSDAY NIGHT...WITH A PARTLY TO MSTLY SUNNY AND WARM FRIDAY IN STORE. COLD FRONT FALLS APART JUST TO THE SE OF C PA...THEN WARM AND HUMID AIR MOVES BACK TO THE NW FRIDAY NIGHT. NEXT FRONT MOVES ACROSS SATURDAY...BUT WEAK SFC TROUGH AND UPPER TROUGH TO LINGER ACROSS THE GREAT LAKES EARLY NEXT WEEK. THUS WENT MAINLY DRY FCST FOR THU AND FRI...THEN CHC FOR SAT... THEN S CHC ON SUNDAY. WENT WITH DRY FCST FOR MONDAY AND TUE. GFS BLOWS UP A SYSTEM OVER SOUTH CENTRAL PA ON MONDAY...BUT THIS NOT CONSISTENT WITH OTHER MODELS AND RUNS...SO THINK IS A CONVECTIVE FEEDBACK PROBLEM. && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/... QUITE VARIABLE CONDITIONS ACROSS THE CWA THIS MORNING. ONGOING CONVECTION MOVING NE WILL CONTINUE TO AFFECT MSOT TAF SITES FOR NEXT COUPLE OF HOURS BEFORE WINDING DOWN FOR SEVERAL HOURS LATE THIS MORNING. THEN CONVECTION WINDS UP AGAIN LATER THIS AFTERNOON INTO THE EVENING...WITH STRONG TO SEVERE STORMS POSSIBLE IN THE EASTERN HALF. THEN THE SYSTEM EVOLVES INTO A POTENTIAL HEAVY RAIN EVENT IN THE CENTRAL/EAST THIS EVENING. THE MAIN WEATHER FEATURE CAUSING THE AFORMENTIONED WEATHER WILL BE THE PERSISTENT UPPER LEVEL TROUGH...WHICH WILL BECOME NEGATIVELY TILTED OVERHEAD TODAY AS A SERIES OF IMPRESSIVE WAVES WITH GOOD JET DYNAMICS SLIDE THROUGH IT. CONVECTION IN THE WESTERN AREAS SHOULD IMPROVE EARLIEST LATER ON TODAY. FURTHER EAST HEAVY RAIN AND THUNDERSTORMS CAN BE EXPECTED TO CONTINUE THROUGH MUCH OF TONIGHT WITH REDUCTIONS TO MVFR AND IFR VISIBILITY AND CEILING EXPECTED. THE FRONT SHOULD FINALLY BE OFFSHORE BY THURSDAY MORNING BRINGING IN VFR CONDITIONS. HOWEVER WE WILL STILL BE UNDER THE UPPER LEVEL TROUGH WHICH MAY CAUSE A FEW ISOLATED AFTERNOON SHOWERS TO DEVELOP...WHICH MAY BRIEFLY LOWER CEILINGS AND VISIBILITIES TO MVFR. VFR CONDITIONS EXPECTED FRIDAY AND SUNDAY... BUT YET ANOTHER FRONT MAY BRING ANOTHER CHANCE OF THUNDERSTORMS ON SATURDAY. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LACORTE/LAMBERT NEAR TERM...LACORTE/LAMBERT SHORT TERM...DANGELO/LAMBERT LONG TERM...MARTIN AVIATION...GARTNER/RXR pa AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ABERDEEN SD 1130 AM CDT WED JUL 23 2008 .UPDATE...REST OF TODAY AREA OF ISO/SCT SHOWERS CONTINUES TO MOVE EASTWARD ACROSS CENTRAL SOUTH DAKOTA LATE THIS MORNING AND WILL APPROACH THE JAMES RIVER VALLEY DURING THE NEXT FEW HOURS. RATHER COMPLEX CONVECTIVE SITUATION TODAY WITH PLENTY OF CLOUD COVER KEEPING INSTABILITY AT BAY TODAY ACROSS THE EAST...ALTHOUGH PRESENCE OF LLJ TODAY SHOULD PROMOTE AN INCREASE IN ELEVATED SHOWERS/STORMS LATER THIS AFTERNOON. FARTHER WEST...SFC BOUNDARY LOCATED ACROSS WESTERN SD WITH IMPULSE MOVING NORTHEAST THROUGH WYOMING. CLEARING LINE APPROACHING WESTERN MOST COUNTIES AND STILL EXPECT SOME DEVELOPMENT OF STORMS ACROSS THIS AREA LATER THIS AFTERNOON AS INSTABILITY INCREASES AND WYOMING IMPULSE NEARS THE AREA. ALSO INCREASED WINDS TODAY INTO THE BREEZY CATEGORY. DID SOME TWEAKS TO ALL OTHER WX ELEMENTS TO BETTER MATCH OBS AND RADAR TRENDS. && .PREV DISCUSSION... .SHORT TERM...TODAY THROUGH FRIDAY MAIN FCST CHALLENGE IN THE SHORT TERM DEALS WITH PCPN CHANCES THROUGH THE PERIOD. CURRENTLY ONGOING MCS LOCATED ACROSS ERN MT/WRN ND...WITH MORE ACCAS TYPE TSRA DEVELOPING IN LLJ REGION OF WRN SD...WITH IR TOPS INDICATING SOME COOLING TAKING PLACE ACROSS SWRN SD. RUC HAS THIS PCPN HANDLED FAIRLY WELL...WITH PCPN ADVECTION MOVING EAST/JUST NORTH OF EAST THROUGH THE REMAINDER OF THE MORNING. HAVE INCLUDED SOME LIKELY POPS FOR THE MORNING HOURS ACROSS SECTIONS OF THE NW CWA TO HANDLE CONVECTION THAT IS CURRENTLY ON GOING/EXPECTED TO DEVELOP. ATTENTION THEN TURNS TOWARD LATER THIS AFTERNOON/THIS EVENING FOR CONVECTIVE CHANCES. MODELS AGREE ON 7H TROF/WAVE COMBO TO IMPACT CWA LATER THIS AFTERNOON...WITH VERY SLOW MOVT EXPECTED WITH 7H TROF. BY 00Z THURSDAY...BOTH GFS/NAM SHOW SHOW QUITE A BIT OF 85H- 7H FRONTOGENESIS TAKING PLACE ACROSS THE MO RIVER REGION...ALONG WITH SPEC HUMIDITIES AOA 10G/KG. 7H TEMPS MAY BE JUST HIGH ENOUGH TO KEEP ATMOS CAPPED THROUGH 21/22Z BEFORE ALLOWING RAPID CONVECTIVE DEVELOPMENT. THE MAIN UNCERTAINITY IN THIS IS THE SKY COVER. CURRENT MCS SHIELD OVERSPREADING CWA...AND THIS MAY BE ENOUGH TO HELP INHIBIT SOME DEVELOPMENT. THINK THAT THE WRN PART OF THE CWA WILL CLEAR OUT ENOUGH LATER THIS AFTN FOR RAPID DESTABILIZATION TO TAKE PLACE. ALSO...NOTICED THAT LOW LEVEL TRAJECTORIES TURN MORE SOUTHERLY AHEAD OF EXPECTED SFC TROF...WHICH SHOULD ALSO ALLOW MORE LOLEVEL MOISTURE TO STREAM NORTHWARD. NOTICED THAT DWPTS ACROSS SC NEB AT 08Z WERE IN THE LOWER 70S. GFS HAS PWATS APPROACHING 2 INCHES BY 00Z TONIGHT. STEERING FLOW LOOKS TO BE SUFFICENT TO PREVENT A LARGE RESIDENCE TIME...SO NO PLANS ON ANY HEAVY RAIN HEADLINES ATTM...BUT LOCALLY HEAVY RAIN IS GOING TO BE POSSIBLE...SO WILL COVER IN THE HWO. WITH WRN PART OF THE CWA ALSO EXPECTED TO CLEAR...WILL COVER PSBL SEVERE IN THE HWO. 7H TROF IS SLOW TO MOVE EAST...SO MECHANISM WILL RESET A BIT FOR THURSDAY...ALTHO HIGHER AXIS OF PWATS DO SHIFT A BIT MORE SOUTH AND EAST. CONCERN IS THAT BOTH NAM/GFS HIGHLIGHT SFC LOW MOVING SLOWLY THROUGH DURING THE DAY. OVERNIGHT CONVECTION LEAVES ERN CWA THURSDAY MORNING...WITH ANOTHER ROUND OF CONVECTION DEVELOPING IN POST FROPA INSTABILITY AXIS WITH NEXT 7H WAVE IMPACTING SLOW MOVING FEATURE. HAVE ADDED IN SOME SLIGHT CHC POPS FOR THURSDAY AFTN...AND THESE WILL NEED TO BE REVISITED DURING LATER SHIFTS TO SEE IF THURSDAY AFTN INSTABILITY DOES INDEED DEVELOP. TEMP WISE...HAVE STUCK PRETTY CLOSE TO INHERITED GRIDS AS TEMPS WILL BE HIGHLY DEPENDANT UPON THE AMOUNT OF CLEARING THAT TAKES PLACE COUPLED WITH HOW MUCH MOISTURE DOES ADVECT NORTHWARD. .LONG TERM...FRIDAY NIGHT THROUGH TUESDAY THE BEST CHANCES FOR THUNDER STILL RESIDE ACROSS THE WESTERN HALF OF FORECAST ZONES...SATURDAY NIGHT AND THEN AGAIN MONDAY AND MONDAY NIGHT...PER THE LATEST 12Z/00Z GFS/EC OPERATIONAL SOLUTIONS. BOTH OF THESE MODELS ARE IN FAIR AGREEMENT ALOFT THROUGH APPX 96 HOURS...BEFORE BEGINNING TO DIVERGE ON TIMING/AMPLITUDE OF MID/UPPER LEVEL TROF/RIDGE AXES OVER THE LOWER 48. BOTH MODELS HINT AT SHORTWAVE TROFPAS SATURDAY NIGHT AND AGAIN SOMEWHERE IN THAT MONDAY/MONDAY NIGHT TIMEFRAME. NO NOTABLE CHANGES MADE TO FRIDAY NIGHT THROUGH SUNDAY AFTERNOON PORTION OF THE EXTENDED WITH THE MORNING FORECAST PACKAGE. && .AVIATION... RATHER COMPLEX AVIATION FORECAST FOR THE NEXT 24 HOURS WITH CONVECTION SCATTERED ACROSS THE CWA. THIS WILL CONTINUE THROUGH THE LATE MORNING AND EARLY AFTERNOON WITH AN ISOLD CB...BUT MORE GENERALLY 8-10KFT BASED SHRA ACTIVITY. ONE CAVEAT IS THAT FROM KMBG TO KBIS THERE IS AN AREA OF MVFR CIGS...BUT EXPECT THIS WILL LIFT OUT AS CLEARING LINE MOVES EAST DURING THE LATE MORNING HOURS. CB ACTIVITY IS EXPECTED TO BECOME MORE WIDESPREAD DURING THE MID TO LATE AFTERNOON...WITH STRONG TO SEVERE STORMS POSSIBLE THIS EVENING MOVING IN A LINE FROM KPIR/KMBG...BUT WILL LIKELY SEE A DECREASE IN ACTIVITY AS THIS LINE MOVES TOWARD THE ATY/KABR TERMINALS LATE THIS EVENING. SYSTEM WILL EVOLVE INTO A HEAVY RAIN PRODUCER WITH BRIEF MVFR/IFR CIGS/VISBY POSSIBLE AS IT MOVES THROUGH KABR/KATY AND POINTS EAST. AS ALWAYS DURING THE SUMMER CONVECTIVE SEASON...AREAS THAT SEE HEAVY RAINFALL TODAY COULD EXPERIENCE FOG DEVELOPMENT OVERNIGHT. WE WILL ALSO SEE A SECOND FRONTAL FEATURE MOVE INTO THE REGION THURSDAY...AND WITH PLENTY OF MOISTURE AROUND...MORE THUNDERSTORM DEVELOPMENT FOR MUCH OF THE AFTERNOON. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...TMT SHORT TERM...HINTZ LONG TERM...DORN AVIATION...CONNELLY WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PADUCAH KY 1140 AM CDT WED JUL 23 2008 .DISCUSSION... REVISED FORECAST TO ELIMINATE ANY MENTION OF PRECIPITATION EXCEPT FOR LOCATIONS NEAR THE ARKANSAS BORDER...NAMELY ALONG AND SOUTH OF A GREENVILLE MISSOURI TO HICKMAN KENTUCKY LINE. THIS AREA HAS YET TO EXPERIENCE THE INFILTRATION OF LOW 60S DEW POINT AIR THAT HAS MADE ITS WAY ACROSS THE REST OF THE FORECAST AREA THIS MORNING. BOUNDARY LAYER DRYING WILL BE SLOW TO OCCUR THIS AFTERNOON IN THE AFOREMENTIONED AREAS...SO MAINTAINED A SLIGHT CHANCE TO ACCOUNT FOR ANY CONVECTION THAT MAY DEVELOP BETWEEN NOW AND NEXT ROUTINE FORECAST ISSUANCE. ALSO TWEAKED TEMPERATURE AND DEW POINT GRIDS DOWN A FEW DEGREES TO ACCOUNT FOR ONGOING TRENDS. && .AVIATION... VFR CONDITIONS WILL PREVAIL THROUGH THURSDAY. ANY THUNDERSTORM DEVELOPMENT SHOULD STAY SOUTH OF AREA FORECAST TERMINALS THIS AFTERNOON. DEVELOPMENT OF FEW-SCT CU IS STILL EXPECTED TODAY... WITH NEARLY CLOUD-FREE SKIES TONIGHT. NORTHEAST WINDS AS HIGH AS 10 KNOTS WILL PREVAIL THE REST OF TODAY...THEN BECOME NEARLY CALM TONIGHT. && .PREV DISCUSSION... /ISSUED 334 AM CDT WED JUL 23 2008/ DISCUSSION... RADARS EARLY THIS MORNING INDICATED A TSTM CLUSTER MOVING SEWD THROUGH THE MO OZARK FOOTHILLS REGION NEAR AN 850 MB WIND CONVERGENCE BOUNDARY. THE RUC MODEL SHOWS THIS PATTERN DISAPPEARING BY 12Z OR SO...AS DRIER AIR FILTERS IN ON THE NOSE OF A SFC HIGH PRESSURE AREA. THIS SHOULD ALL BUT ELIMINATE CHCS OF PCPN BY AFTN EVEN NEAR THE AR/TN BORDER. THE PAH FCST AREA WILL BE RAIN FREE THROUGH THU AFTN...THEN THE MID LEVEL FLOW OVER OUR REGION IS PROGGED TO TAKE ON A MORE WRLY COMPONENT AS AN ERN GREAT LAKES LOW DEPARTS INTO CANADA. THIS SHOULD RESULT IN THE EWD EXPANSION OF THE SWRN CONUS MID LEVEL RIDGE AND THE REINTRODUCTION OF WARM MOIST AIR FROM THE SW ON THU NIGHT/FRI. SCT SHWS/TSTMS WILL PROBABLY RESULT IN THE VICINITY OF THE WARM FRONT. FRI NIGHT PCPN CHCS WILL DECREASE SOME... ESPECIALLY IN SERN MO AS SHRTWV ENERGY EVENTUALLY TURNS LOW LEVEL WINDS BACK TO THE NORTH...TENDING TO DRY OUT THE ATMOSPHERIC COLUMN. THIS WRN RIDGE/ERN TROF PATTERN IS EXPECTED TO CONTINUE...WITH AN ON AND OFF PCPN PATTERN LASTING AT LEAST THROUGH THE WEEKEND AS SHRTWV ENERGY IMPULSES MOVE THROUGH THE NWLY MID LEVEL PATTERN. ALL IN ALL...POPS ARE NOT VERY HIGH. FURTHER INTO NEXT WEEK...MODELS ARE IN GOOD AGREEMENT THAT DRIER NWRLY FLOW APPEARS TO WIN OUT FOR MUCH OF THE WEEK. TEMPS WILL BE MODERATE FOR THIS TIME OF YEAR && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ RJP/DB ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CARIBOU ME 355 PM EDT WED JUL 23 2008 .SYNOPSIS... LOW PRESSURE OVER THE EASTERN GREAT LAKES WILL SLOWLY MOVE TO THE EAST. THIS SYSTEM IS EXPECTED TO SPREAD SHOWERS ACROSS THE REGION LATER TONIGHT AND THURSDAY. A SLOW MOVING COLD FRONT WILL CROSS THE REGION THURSDAY NIGHT AND FRIDAY BRINGING RAIN WITH A CHANCE OF THUNDERSTORMS. && .NEAR TERM /THROUGH THURSDAY/... LOW PRESSURE AT THE SURFACE AND ALOFT WILL CONTINUE TO DEVELOP OVER THE EASTERN GREAT LAKES. THIS SYSTEM...PARTICULARLY THE UPPER LEVEL SYSTEM IS UNUSUALLY DEEP FOR THIS TIME OF THE YEAR. ALL GUIDANCE HAS BEEN SHOWING A TREND TO SLOW EASTWARD PROGRESSION OF THIS SYSTEM LAST FEW DAYS. MODELS MAY STILL BE A LITTLE TOO FAST ESPECIALLY WITH THE FLOW ALOFT BECOMING PARALLEL TO THE FRONT. SO STRATEGY WILL BE TO FOLLOW THIS TREND AND DELAY INCREASE IN POPS AND QPF. NOT PARTICULARLY SATISFIED WITH ANY COMBINATION OF MODEL POPS SO HAVE GENERATED THIS GRID MANUALLY. FOR QPF HAVE USED GFS FOR TODAY INTO TONIGHT THEN TRANSITION TO HPC. WILL INCLUDE SCATTERED THUNDERSTORMS IN FORECAST FOR THURSDAY AFTERNOON. FOR TEMPERATURE...WIND AND DEW POINTS HAVE USED GMOS. HAVE NOT MADE ANY CHANGES TO SKY COVER WHICH CONTINUES TO BE MOSTLY CLOUDY. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... A SLOW MOVING COLD FRONT WILL CROSS THE REGION LATER THURSDAY NIGHT THROUGH EARLY FRIDAY AFTERNOON. MODELS CONTINUE TO INDICATE A LOW LEVEL JET TRANSPORTING ABUNDANT MOISTURE NORTH IN ADVANCE OF THE FRONT...WITH PRECIPITABLE WATER VALUES APPROACHING 2 INCHES. ALONG WITH THE FRONTAL LIFT...AN UPPER LEVEL JET WILL ENHANCE LIFT ACROSS THE REGION IN ADVANCE OF THE FRONT. THE COMBINATION OF ABUNDANT MOISTURE...ENHANCED LIFT AND UPSLOPING OF MOISTURE INTO HIGHER TERRAIN AREAS WILL LEAD TO THE POSSIBILITY OF HEAVY RAIN ALONG THE FRONT ACROSS PORTIONS OF THE REGION LATER THURSDAY NIGHT THROUGH EARLY FRIDAY AFTERNOON...THOUGH UNCERTAINTY STILL EXISTS REGARDING PRECIPITATION AMOUNTS AND THE LOCATION OF THE HEAVIEST PRECIPITATION. AN AREA OF RAIN WILL CROSS THE REGION IN ADVANCE OF THE FRONT...ALONG WITH A CHANCE OF THUNDERSTORMS...THURSDAY NIGHT THROUGH EARLY FRIDAY AFTERNOON WITH PRECIPITATION TAPERING TO SHOWERS IN THE WAKE OF THE FRONT LATER FRIDAY AFTERNOON. SHOWERS COULD LINGER ACROSS MOSTLY NORTHERN AREAS FRIDAY NIGHT. UNSETTLED CONDITIONS WILL PERSIST SATURDAY INTO SATURDAY NIGHT WITH AN UPPER LEVEL DISTURBANCE CROSSING THE REGION SATURDAY AND A COLD FRONT APPROACHING SATURDAY NIGHT. TEMPERATURES WILL BE AT NEAR NORMAL LEVELS FRIDAY AND SATURDAY. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... UPPER LEVEL PATTERN FORECAST NOT ALL THAT DIFFERENT THAN YESTERDAYS FORECAST GUIDANCE. A BROAD UPPER LEVEL RIDGE WILL REMAIN PARKED OVER THE MIDWEST THROUGH THE PERIOD. COMPUTER MODELS DIFFER SOMEWHAT BEYOND MONDAY. ENSEMBLE MEAN MEMBERS FROM THE GFS INDICATE A MORE AMPLIFIED RIDGE IN THE MIDWEST THAT ITS OPERATIONAL COUNTERPART. HPC NOTED A COMMON OPERATIONAL BIAS CONCERNING THIS TYPE OF SCENARIO. HAVE INITIALIZED THE EXTENDED FORECAST WITH GMOS. HOWEVER...ON DAYS 6 AND 7 DECIDED TO GO WITH GFS ENSEMBLE GUIDANCE. THE AFFECT OF THIS WAS TO RAISE POPS BACK ABOVE CLIMO FOR NORTHERN TIER ZONES. ALL IN ALL...THERE IS A MODERATE DEGREE && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... EXPECT MVFR/IFR CONDITIONS MAINLY DUE TO CEILINGS TO PERSIST TONIGHT AND THURSDAY. SOME FOG IS POSSIBLE KBGR AND KBHB AFTER 06Z. CEILINGS/VISIBILITIES WILL BE REDUCED IN RAIN AND FOG...WITH A CHANCE OF THUNDERSTORMS...THURSDAY NIGHT THROUGH EARLY FRIDAY AFTERNOON. IFR/LIFR CONDITIONS WILL BE COMMON ACROSS THE REGION LATER THURSDAY NIGHT THROUGH EARLY FRIDAY AFTERNOON. CONDITIONS WILL THEN IMPROVE LATER FRIDAY AFTERNOON. GENERALLY VFR CONDITIONS ARE EXPECTED FRIDAY NIGHT THROUGH SATURDAY...THOUGH THERE WILL BE A CONTINUING CHANCE OF SHOWERS AND POSSIBLE THUNDERSTORMS. CEILINGS/VISIBILITIES SHOULD BEGIN TO LOWER AGAIN LATER SATURDAY NIGHT WITH MORE EXTENSIVE SHOWERS DEVELOPING. && .MARINE... NEAR TERM: HAVE INITIALIZED THE WIND GRIDS WITH THE RUC13 OUT TO 03Z THEN TRANSITION TO A 50/50 BLEND OF THE NAM12 AND GFS40 FOR THE REMAINDER OF THE FORECAST PERIOD. EXPECT SLIGHTLY HIGH WIND SPEED BIAS...ESPECIALLY AS AIR TEMPERATURES INCREASE RELATIVE TO COLD SEA SURFACE TEMPERATURES THURSDAY. SO WILL LOWER SPEEDS 1 TO 2 KNOTS. FOR WAVES: A PERSISTENT SOUTHERLY FLOW WILL CONTINUE TO DEVELOP TO THE EAST AND SOUTH OF NEW ENGLAND. DUE TO THIS SOUTHERLY FETCH A COMBINATION OF WIND WAVE AND LONGER PERIOD SWELL WILL CONTINUE. HAVE INITIALIZED WAVE GRIDS WITH WNA WAVES TONIGHT AND EARLY THURSDAY THEN TRANSITION TO THE NAM VERSION OF SWAN. EXPECT HIGH BIAS FOR WAVE MODEL WINDS IN LOCAL WATERS THURSDAY...SO WILL LOWER WAVE HEIGHTS TO COMPENSATE. DEW POINTS EXPECTED TO INCREASE TONIGHT SO WILL TRANSITION FROM AREAS TO WIDE SPREAD FOG AFTER 06Z. SHORT TERM: SEAS COULD BE AT MARGINAL SMALL CRAFT ADVISORY LEVELS THURSDAY NIGHT INTO SATURDAY...IN MOSTLY A SOUTH SWELL. WINDS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY LEVELS THURSDAY NIGHT THROUGH SATURDAY NIGHT. VISIBILITIES WILL BE REDUCED IN RAIN AND FOG WITH A CHANCE OF THUNDERSTORMS THURSDAY NIGHT THROUGH FRIDAY...WITH LINGERING SHOWERS POSSIBLE FRIDAY EVENING. SHOWERS AND POSSIBLE THUNDERSTORMS ARE THEN EXPECTED SATURDAY INTO SATURDAY NIGHT. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...NONE. && $$ NEAR TERM...MIGNONE SHORT TERM...NORCROSS LONG TERM...LERICOS AVIATION...MIGNONE MARINE...MIGNONE/NORCROSS me AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 145 PM EDT WED JUL 23 2008 UPDATED FOR THE 18Z TAFS .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SLOWLY DEPARTING UPR TROF OVER SE ONTARIO DOWNSTREAM OF HI AMPLITUDE RDG EXTENDING FM THE PLAINS INTO SCNTRL CAN. AT THE SFC/H85...SPRAWLING HI PRES CENTERED OVER NRN ONTARIO. BACK EDGE OF DEEPER MSTR ASSOCIATED WITH THE TROF IS IN ERN UPR MI WITH LINGERING SCT-BKN MID CLD. TO THE W AND NW...00Z INL/YPL RAOBS ARE QUITE DRY/STABLE WITH PWAT JUST A BIT OVER 0.50 INCH/WELL DEFINED CAP ARND H7 ABV WELL MIXED PBL. AFTN DIURNAL CU IN THESE AREAS YDAY GAVE WAY TO MOCLR SKIES DURING THE EVNG. MAIN FCST CONCERNS INTO THU REVOLVE ARND TEMPS WITH ONTARIO HI PRES/ DRY AIRMASS FCST TO DOMINATE. FOCUS FOR THU NGT THRU FRI NGT SHIFTS TO TIMING/IMPACT OF TROF NOW IN THE PAC NW TO THE W OF UPR RDG IN THE PLAINS. FOR TDAY/TNGT...DRY HI PRES FCST TO BLD OVER THE UPR GRT LKS AND TO NR MNM BY 12Z THU. ALTHOUGH THERE WL BE SCT DIURNAL CU OVER THE INTERIOR CWA THIS AFTN AWAY FM THE STABILIZING INFLUENCE OF THE GRT LKS...EXPECT MOCLR SKIES OTRW. THE ONLY OTHER EXCEPTION MAY BE OVER THE FAR ERN CWA TNGT...WHERE ANOTHER SHRTWV ROTATING ARND NRLY STNRY CLOSED LO THE E MAY BRING SOME CLD IN TNGT. DRY AIRMASS SUGS A WIDE DIURNAL VARIATION IN TEMP BTWN THIS AFTN/TNGT. WITH H85 TEMPS FCST ARND 12C BY 00Z THU...EXPECT HI TEMPS TO APRCH 80 AWAY FM LK COOLING MOST PRONOUNCED DOWNWIND OF LK SUP AND THE BAY OF GREEN BAY S OF ESC WITH NLY H925 FLOW MINIMIZING LK MI INFLUENCE AT AREAS E OF ESC. MIXING TO H75-8 TDAY WOULD SUG SFC DWPTS WL FALL INTO THE MID 40S PER 00Z INL RAOB/GFS FCST SDNGS...RESULTING IN MIN RH FALLING AOB 30 PCT OVER THE INTERIOR. ALTHOUGH DVLPG RETURN SSW FLOW LATE TNGT MAY TEND TO BRAKE FALL OF TEMP OVER THE FAR W AT IWD- ONTONAGON...WL GO BLO MOS GUIDANCE OVER MOST OF THE INTERIOR TO THE E WITH PROMISE OF LGT WINDS/CLR SKIES. STUBBORN UPR LO IN ONTARIO IS PROGGED TO LIFT SLOWLY TO THE NE ON THU...BUT LARGER SCALE ACYC FLOW IS PROGGED TO LINGER UNDER RDG AXIS JUST TO THE NW THAT WL BE WEAKENING AS PAC NW TROF PRESSES INTO SCNTRL CAN. ANTECEDENT DRY AIRMASS...PERSISTENCE OF RDGING/ACYC FLOW UPSTREAM OF STUBBORN BLOCK TO THE E...AND INTERCEPTION OF RETURNING DEEPER MSTR CLOSER TO WARM FNT WELL TO THE S WOULD SUG DRY...CAPPED NAM IS ON THE RIGHT TRACK AND GFS IS TOO AGGRESSIVE AT GENERATING PCPN OVER THE WRN ZNS IN THE AFTN. BUT WL RETAIN GOING LO CHC POPS TO ACCOUNT FOR GFS FCST AND RATHER HI ETA MOS POP AS WELL FOR IWD. DESPITE SOME INCRS IN CLD COVER...TEMPS WL BE AOA EXPECTED MAX TEMPS FOR TDAY WITH H85 TEMPS A DEGREE OR TWO WARMER AND RETURN SW FLOW MINIMIZING LK SUP COOLING. THE EXCEPTION WL BE ALONG/DOWNWIND OF THE LK MI SHORE. AS INCOMING UPR TROF ACRS SRN CAN BREAKS DOWN RDG A BIT MORE THU NGT...ASSOCIATED SFC COLD FNT IS PROGGED TO ARPCH WRN LK SUP BY 12Z FRI...GFS A BIT FASTER THAN NAM. PER NCEP GUIDANCE...FOLLOWED COMPROMISE 00Z UKMET/12Z ECMWF FOR TIMING...WHICH SHOW THE BNDRY REACHING THE MN/LK SUP AT 12Z FRI. SINCE SHARP WARM FNT REMAINS WELL TO THE SW...MSTR INFLOW WL BE LIMITED...AND MODEL QPFS ARE RATHER MODEST. 12Z ECMWF IS A BIT MORE AGGRESSIVE THAN THE 00Z UKMET WITH HGT FALLS/DPVA/DEEP LYR QVECTOR CNVGC ASSOCIATED WITH INCOMING TROF...ESPECIALLY OVER WRN UPR MI. WL THUS CARRY A 30 POP OVER THE NW BUT KEEP THE ERN ZNS DRY SO FAR E OF THE INCOMING BNDRY AT DIURNAL MIN HTG TIME. ECMWF/UKMET SHOW SSI ARND +4C AT ERY THRU THE NGT...AND NAM FCST SDNGS ARE QUITE DRY IN THE MID LVLS. BULK OF NUMERICAL GUIDANCE SHOWS COLD FNT REACHING THE SCNTRL AND E LATE IN THE DAY ON FRI. PCPN CHCS ON FRI WL BE LIMITED BY WEAK LLVL CNVGC ALG THE FNT...LIMITED MSTR INFLOW...AND QUITE A BIT OF DRY MID LVL AIR. ON THE OTHER HAND...LACK OF CLD COVER WOULD SUG A GOOD DEAL OF INSOLATION/DESTABILIZATION. PLACEMENT OF FA IN LEFT EXIT OF JET MAX SUPPORTING INCOMING TROF SHOWN MOST BY 12Z ECMWF ALG WITH SOME FAIRLY SHARP DVPA/DEEP LYR QVECTOR CNVGC WOULD ADD LARGER SCALE LIFT. BUT THE 00Z GFS/UKMET SHY AWAY FM THIS STRONGER JET SCENARIO... SO OPTED TO REDUCE POPS A BIT TO NO MORE THAN 30 EXCEPT OVER THE FAR SCNTRL AND E WHERE LATER ARRIVAL OF FNT WL BE MOST IN SYNC WITH DIURNAL HTG CYCLE AND SOME LK BREEZE CNVGC. GOING 40 POP SEEMS APPROPRIATE THERE. TENDED TOWARD THE HI END OF MOS GUIDANCE FOR MAX TEMPS EXCEPT OVER THE W DOWNWIND OF LK SUP/NEAR LK MI WITH DOWNSLOPING WNW FLOW/EXPECTED DECENT AMT OF SUNSHINE. INCRSG UNIDIRECTIONAL WINDS IN THE LO/MID TROP (0-6KM BULK SHEAR FCST TO INCRS TO 40 KTS) AND PRESENCE OF DRY MID LVL AIR WOULD SUG A RISK FOR SOME SVR STORMS. MODIFIED GFS FCST SDNG FOR MNM FOR SFC T/TD 83/60 AND SOMEWHAT COOLER MID LVL TEMPS TO ACCOUNT FOR POTENTIAL OF STRONGER JET DYNAMICS THAN EXPLICITLY FCST BY 00Z GFS YIELDS SB CAPE ARND 930 J/KG. BUT LAPSE RATES...EVEN WITH A DEGREE OR SO OF MID LVL COOLING...DO NOT APPEAR PARTICULARLY STEEP. SINCE SPC DOES NOT HAVE UPR GRT LKS OUTLOOKED FOR MENTION OF SVR STORMS...WL LEAVE OUT MENTION FOR NOW. WITH LOSS OF DIURNAL HTG FRI NGT AND FAIRLY STRONG MID LVL DRYING IN WAKE OF COLD FROPA...TENDED TO END POPS FASTER W-E THAN PREVIOUS FCST. BUT MAINTAINED LO CHC POPS OVER LK SUP THRU THE NGT AND INTO SAT CLOSER TO DIGGING SHRTWV THRU ONTARIO AND SOMEWHAT DEEPER MSTR. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... SURFACE HIGH PRESSURE WILL BE OVERHEAD TODAY...AND MOVE TO THE OHIO VALLEY BY THURSDAY MORNING. EXPECT VFR CIGS AND VIS THROUGH THE PERIOD WITH TRADITIONAL DIURNAL WINDS...LIGHT AND VARIABLE DURING THE OVERNIGHT HOURS. THE ONLY FLY IN THE OINTMENT SHOULD BE WITH CLOUDS LATE IN THE PERIOD AND SHORTLY AFTER...ASSOCIATED WITH AN APPROACHING COLD FRONT. THESE TOO SHOULD REMAIN VFR AT LEAST THROUGH 18Z. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... THE HIGH PRESSURE OVER THE UPPER GREAT LAKES WILL KEEP WINDS LESS THAN 15 KNOTS THROUGH THURSDAY. AS THIS HIGH DRIFTS EAST ON FRIDAY...A LOW PRESSURE TROUGH WILL MOVE INTO THE UPPER GREAT LAKES CAUSING SOUTHERLY WINDS TO INCREASE AND VEER TO THE WEST. AS THIS TROUGH DRIFTS INTO THE CENTRAL GREAT LAKES ON SATURDAY...THE WINDS WILL SHIFT NORTHWEST AGAIN. OTHERWISE...WINDS WILL BE NO GREATER THAN 20 KNOTS THIS WEEK END. WAVES WILL STILL REMAIN 3 FEET OR LESS THROUGH THE PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...KC AVIATION...KF/MRC MARINE...DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 310 PM CDT WED JUL 23 2008 .SHORT TERM...TONIGHT THROUGH SATURDAY FORECAST CONCERNS THROUGH THE PERIOD WILL FOCUS ON PRECIPITATION CHANCES LATER TONIGHT THROUGH FRIDAY EVENING. SURFACE MAP THIS AFTERNOON HAD A RIDGE OF HIGH PRESSURE CENTERED OVER WI/UPPER MICHIGAN WHILE A TROUGH OF LOW PRESSURE WAS LOCATED FROM WESTERN SD THROUGH EASTERN CO. FAIRLY NARROW CORRIDOR OF LOW LEVEL MOISTURE TRANSPORT/CONVERGENCE AHEAD OF THE TROUGH WAS MAINTAINING CLUSTERS OF SHRA/OCNL THUNDER ACROSS THE EASTERN DAKOTAS. THIS HAS BEEN ONGOING ALL DAY. OTHERWISE...TEMPERATURES CURRENTLY IN THE MID AND UPPER 70 AND DEW POINTS IN THE 50S TO LOWER 60S ACROSS THE LOCAL FORECAST AREA FAIRLY ATYPICAL FOR LATTER JULY. 23.12Z GFS/NAM SHORT TERM MODELS IN FAIRLY GOOD AGREEMENT WITH NO GLARING DIFFERENCES NOTED. THE RIDGE OF HIGH PRESSURE WILL DRIFT SLOWLY EAST INTO THE GREAT LAKES REGION TONIGHT AS THE TROUGH OVER THE NORTHERN PLAINS BUDGES INTO WESTERN MN THROUGH EASTERN NEB BY 12Z. EASTERN PERIPHERY OF 925-700MB MOISTURE TRANSPORT AHEAD OF THE TROUGH WILL EDGE INTO WESTERN SECTIONS OF THE FORECAST AREA AFTER MIDNIGHT...THICKENING CLOUD COVER AND BRINGING A CHANCE OF PRECIPITATION TO AREAS ALONG AND WEST OF THE MISSISSIPPI RIVER. MUCAPE NOT ALL THAT IMPRESSIVE ...SO CARRIED SHRA/ISOLATED THUNDER MENTION FOR AREAS WEST OF THE MISSISSIPPI AFTER MIDNIGHT. THE TROUGH WILL REMAIN FAIRLY STATIONARY ACROSS WESTERN MN/EASTERN NEB THROUGH THURSDAY WITH THE MAIN SLUG OF LOW LEVEL MOISTURE TRANSPORT STAYING ALONG AND SOUTH OF I-80 ACROSS IA THROUGH THE DAY. THIS WILL FUEL A CLUSTER OF THUNDERSTORMS ACROSS EASTERN IA/NORTHWEST IL BY TOMORROW MORNING WITH NORTHERN PERIPHERY OF THIS STRONGER TRANSPORT SIGNAL EDGING INTO SOUTHEAST MN/NORTHEAST IA COUNTIES. BASED ON THIS SIGNAL...CARRIED LIKELY SHRA/T CHANCES ACROSS THAT AREA IN THE 12-18Z TIME FRAME. MODELS STILL SHOWING A SECONDARY LIGHTER MOISTURE TRANSPORT SIGNAL FURTHER NORTH ACROSS THE AREA FOR A SMALLER CHANCE OF SHRA/T. AGAIN...MUCAPE IS NOT THAT IMPRESSIVE...SO WOULD EXPECT MAINLY SHRA WITH PERHAPS A RUMPLE OR TWO OF THUNDER. WITH CLOUD COVER AND SCATTERED CONVECTION IN THE AREA THURSDAY...TEMPERATURES WILL BE BE WELL BELOW NORMAL TOPPING OFF IN THE MID 70S TO UPPER 70S. WEAK LOW-LEVEL MOISTURE TRANSPORT AHEAD OF THE TROUGH WILL CONTINUE SHRA/ISOLD T CHANCES ACROSS THE AREA THURSDAY NIGHT. ON FRIDAY...A STRONGER MID-LEVEL SHORTWAVE TROUGH COMING ACROSS THE NORTHERN PLAINS WILL TRANSITION THE SURFACE TROUGH INTO A COLD FRONT AND PUSH IT INTO THE AREA BY AFTERNOON. MOISTURE TRANSPORT NOT PARTICULARLY STRONG AHEAD OF THIS WAVE...BUT BUILDING CAPE INTO THE 1000-2000J/KG RANGE WITH SURFACE HEATING AHEAD OF THE FRONT SHOULD BE AMPLE FOR SCATTERED SHRA/TS ACTIVITY. BUMPED POPS INTO TE 30-40 PERCENT RANGE BASED ON THIS FOR THE AFTERNOON HOURS ON FRIDAY. THE FRONT WILL DROP SLOWLY SOUTHEAST ACROSS THE AREA THROUGH THE EVENING HOURS FRIDAY WITH LINGERING SHRA/TS CHANCES...THEN EXIT THE AREA AROUND MIDNIGHT. SLIGHTLY COOLER AND DRIER CANADIAN AIRMASS WILL SETTLE INTO THE AREA ON SATURDAY FOR PLEASANT CONDITIONS. .LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY 23.00Z/06Z MEDIUM RANGE MODELS SHOWING FRONTAL BOUNDARY SETTLING WELL SOUTH OF THE AREA SATURDAY NIGHT/SUNDAY TIME FRAME. MODELS HAVE A WEAK MID-LEVEL SHORTWAVE TROUGH RIPPLING ALONG THE FRONTAL BOUNDARY WITH PERHAPS THE NORTHERN EDGE OF RESULTANT SHRA/TS ACTIVITY TOUCHING FAR SOUTHERN SECTIONS OF THE FORECAST AREA. GFS ENSEMBLE OF PRECIPITATION PROBABILITIES KEEP EVERYTHING SOUTH...SO HAVE OPTED TO GO WITH A DRY FORECAST FOR NOW. WILL BUMP UP CLOUD COVER SOMEWHAT AS ALMOST CERTAIN THAT SOME CONVECTIVE DEBRIS CLOUDS WILL AT LEAST AFFECT SOUTHERN PORTIONS OF THE AREA. THEN FOR MONDAY THROUGH WEDNESDAY...THE GEM/DGEX/GFS ENSEMBLES AMPLIFY RIDGING ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST REGION. THE DETERMINISTIC GFS/ECMWF WANT TO BLOW A COLD FRONT THROUGH THE RIDGE IN THE TUESDAY/WEDNESDAY TIME FRAME...BUT THIS SEEMS LIKE AN OUTLIER SOLUTION GIVEN THE STRENGTH OF THE RIDGE. WILL GO WITH A DRY FORECAST FOR NOW. GFS AND ECMWF KEEP 850MB TEMPERATURES IN CHECK THROUGH THE PERIOD WITH THE GFS STARTING OUT IN THE 10-13C RANGE ON SUNDAY...WARMING TO AROUND 16-17C BY WEDNESDAY. THE ECMWF IS SLIGHT COOLER. BOTTOM LINE...IT WILL BE DRY WITH TEMPERATURES JUST A FEW DEGREES BELOW SEASONAL NORMALS. && .AVIATION...TONIGHT THROUGH THURSDAY MORNING 12Z MODELS IN GOOD AGREEMENT OF DEVELOPING A CONVECTIVE COMPLEX OVER WESTERN MINNESOTA THIS EVENING AND BRINGING THIS EAST/SOUTHEAST THROUGH THURSDAY MORNING. BY LATE TONIGHT INTO THURSDAY MORNING...THE LOW LEVEL JET AND MOISTURE TRANSPORT REALLY STARTS TO TAKE A TURN TO THE SOUTHWEST AND BECOMES MORE FOCUSED OVER SOUTHEAST IOWA. THIS WOULD SUGGEST THAT THE COMPLEX SHOULD BE ON A DIMINISHING TREND AS IT APPROACHES THE AREA. THE CONCERN BECOMES WHETHER THIS WILL HOLD TOGETHER LONG ENOUGH TO BRING ANY RAIN TO THE TAF SITES. PREVIOUS TAFS INTRODUCED VCSH FOR KRST AND HAVE CONTINUED THIS TREND BUT PUSHED THE TIMING BACK A LITTLE FOR A SLOWER ARRIVAL. THE NAM HAS BEEN CONSISTENT FOR A COUPLE RUNS OF SHOWING THE RAIN REACHING KLSE AS WELL. THE 23.09Z SREFS DO BRING IN PROBABILITIES OF 30-40 FOR KLSE AND BOTH THE 23.00Z ARW WRF AND 23.09Z RUC WRF SUGGEST THE RAIN WILL REACH KLSE SO HAVE INTRODUCED A VCSH THERE AS WELL. NO CAPE IS FORECAST TO BE PRESENT THROUGH 18Z THURSDAY SO NO MENTION OF THUNDER OR INCLUSION OF CB. CEILINGS EXPECTED TO STAY ABOVE 5K FEET FOR THE MOST PART. THE 23.12Z NAM BUFKIT SOUNDINGS SUGGEST KRST MAY GO DOWN TO 3K FEET OR LOWER BY MID TO LATE MORNING. OBSERVATIONS OVER SOUTH DAKOTA WITH THE RAIN THIS MORNING DID INDICATE MVFR CEILINGS SO HAVE TRENDED TOWARD THIS POSSIBILITY. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT/LONG TERM...DAS AVIATION..........04 wi