AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 945 PM MDT MON AUG 22 2005 .SHORT TERM ... UPDATE...HAVE BOOSTED POPS FOR THE REMAINDER OF THE NIGHT AND TUESDAY MORNING. SHORT WAVE WILL MOVE ACROSS ERN UTAH LATER TONIGHT AND WILL BE POSITIONED OVER WRN COLORADO BY TUESDAY MORNING. CURRENT LIGHTNING DATA AND SATELLITE IMAGES SUGGEST THAT CONVECTIVE ACTIVITY OVER SWRN UTAH IS NOT DIMINISHING DESPITE THE LOST OF SURFACE HEATING. SPEED MAXIMA IN ADVANCE OF TROUGH AXIS WILL PROVIDE UPPER LEVEL DIVERGENCE OVERNIGHT OVER THE WRN HALF OF THE FORECAST AREA TONIGHT AND THEN SHIFTS EASTWARD ON TUESDAY. IN ADDITION...THERE/S DECENT VORTICITY ADVECTION IN THE H5-H3 LAYER INDICATING UPWARDS FORCING. NAM MODEL HAS BEEN CONSISTENT IN INCREASING PCPN DURING THE OVERNIGHT HOURS...AND IT APPEARS THE RUC MODEL IS COMING AROUND TO THIS IDEA. SO INSTEAD OF HAVING 15-20 PERCENT POPS FOR MOST OF THE FORECAST AREA...HAVE BOOSTED THEM AROUND 30 PERCENT OVERNIGHT AND TUESDAY MORNING TO COINCIDE WITH INCOMING WAVE. (TUESDAY THROUGH WEDNESDAY)... STRONGER PAC TROUGH MOVES ACROSS THE US/CANADIAN BORDER TUE AND WED. WHILE MOST OF THE ENERGY STAYS TO OUR N...IT DOES DRIVE AN ASSOCIATED COLD FRONT INTO NRN UT/SWRN WY BY WED EVENING. THE APPROACHING FRONT ALONG WITH INCREASED PRESSURE GRADIENT SHOULD PRODUCE BREEZIER CONDITIONS WED...ESPECIALLY ACROSS THE NORTH. NOT A BIG FIRE WX CONCERN AT THE MOMENT AS WINDS AND RH ARE EXPECTED TO STAY ABOVE CRITICAL FIRE WX LEVELS...BUT BEARS WATCHING. .LONG TERM (WEDNESDAY NIGHT THROUGH MONDAY)...THE NORTHERN TROUGH WILL SLOWLY MOVE ONTO THE PLAINS THURSDAY. THEN THE SUBTROPICAL HIGH, STRETCHED ACROSS THE SOUTHERN TIER OF STATES, AMPLIFIES SOMEWHAT. EARLY NEXT WEEK, THE NEXT PACIFIC TROUGH DEEPENS ACROSS THE WESTERN STATES VEERING OUR FLOW TO SW. GENERALLY THOUGH THE SUBTROPICAL RIDGE WILL LIMIT MOISTURE SURGES AND HELP STEER ANY EASTERN PACIFIC TROPICAL STORMS AWAY FROM CONUS FOR GENERALLY BELOW NORMAL RAINFALL. TEMPERATURES WILL REMAIN NEAR OR JUST ABOVE NORMAL. .GJT WATCHES/WARNINGS/ADVISORIES... .CO...NONE. .UT...NONE. && PF/JAD/JOE co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 933 PM EDT MON AUG 22 2005 .DISCUSSION... WITH THE SETTING SUN ANY SHOWER ACTIVITY IS COMING TO AN END ALONG A WEAK FRONTAL BOUNDARY NOW DRIFTING SLOWLY SOUTHWARD ACROSS THE CENTRAL PORTIONS OF THE CWA. BASED ON THIS EVENINGS UPPER AIR CHARTS...THE SHOWERS AND THUNDERSTORMS APPEARS TO HAVE DEVELOPED ALONG THE 850H FRONT...POSSIBLY WITH SOME HELP FROM A PASSING UPPER LEVEL SHORT WAVE AS WELL. WITH THE VERY LIMITED ACTION OVER OUR CWA...HAVE BEEN HANDLING THE ISOLD EVENTS WITH SHORT TERM FORECASTS. OTHER THAN THE SHOWERS...THE CURRENT FORECAST HAS BEEN RIGHT ON TRACK AND THE GRIDS ARE IN VERY GOOD SHAPE. SO UPDATE TONIGHT WILL ONLY BE FOR EVENING SPRINKLES WORDING. WILL ISSUE NEW ZONES ONCE ALL SHOWER ACTIVITY HAS ENDED...WHICH IS EXPECTED WITHIN THE HOUR. && .PREV DISCUSSION... 500 PM EDT MON AUG 22 2005 20Z SFC ANALYSIS SHOWS THE CORE OF THE HIGH PRESSURE LOCATED OVER THE GREAT LAKES REGION WITH A SECONDARY...OR TERTIARY...COLD FRONT PRESSING SOUTH INTO NORTHERN KENTUCKY. ALONG THIS BOUNDARY A LINE OF SCATTERED TO BROKEN CONVECTIONS HAS BROKEN OUT...THE STRONGEST OF THESE LIKELY CONTAINING SMALL HAIL AND GUSTY WINDS. JUST TO THE SOUTH OF THIS...AN AREA OF SPRINKLES AND VIRGA IS DRIFTING THROUGH SOUTHEAST KENTUCKY. DESPITE THE FRONT TO THE NORTH THE DEWPOINTS TODAY WERE ABOUT 10 DEGREES LOWER THAN YESTERDAY. WITH TEMPS A GOOD 5 DEGREES OR SO COOLER...BUT SOME CREDIT FOR THIS MUST GO TO THE HIGH AND...NOW INCREASINGLY...MID LEVEL CLOUDS THAT PLAGUED US FOR MUCH OF THE DAY. THE MODELS CONTINUE TO BE IN GOOD AGREEMENT WITH THE MAIN FEATURES AFFECTING THE LONGWAVE PATTERN FOR MOST OF THE WEEK AS A MINI OMEGA BLOCK SETS UP OVER NORTHEAST CANADA. THE QUEBEC CLOSED LOW WILL ONLY SLOWLY PIVOT EAST SENDING ITS AXIS THROUGH KENTUCKY DURING THE DAY WEDNESDAY. AHEAD OF THIS...MINOR WAVES WILL MOVE OUT OF THE SOUTHERN PLAINS AND PASS OVER KENTUCKY ENHANCING THE PRECIPITATION POTENTIAL OF A RELATIVELY DRY FRONTAL BOUNDARY THAT SETTLES INTO SOUTHERN KENTUCKY AND NORTHERN TENNESSEE. A RIDGE WILL BUILD INTO THE REGION IT IS WAKE BEFORE FLATTENING OUT TO END THE WORK WEEK. MEANWHILE ...A LESS WELL HANDLED UPPER LOW WILL SLOWLY ROLL EAST THROUGH SOUTHWEST AND CENTRAL CANADA ALSO STALLING AS IT APPROACHES HUDSON BAY. THE SFC FEATURES ASSOCIATED WITH THIS UPPER LOW WILL LIKEWISE ENTER THE OHIO VALLEY AND STALL OUT NEAR KENTUCKY FOR THE WEEKEND. SENSIBLE WEATHER WILL FEATURE A WEST TO EAST BAND OF SCATTERED SHOWERS AND THUNDERSTORMS DISSIPATING AS IT SINKS THROUGH NORTHERN KENTUCKY. OUT AHEAD OF THIS BOUNDARY POCKETS OF SPRINKLES WILL BE FOUND FOR THE FIRST PART OF THE NIGHT. OTHERWISE...CLEARING SKIES TO THE NORTH WILL COMBINE WITH SOME CAA TO SEND TEMPERATURES INTO THE LOWER 60S AND UPPER 50S BY MORNING. TO THE SOUTH SOME DIMINISHMENT OF THE CLOUDS AND ADVECTION WILL ALSO DROP TEMPS INTO THE LOWER AND MIDDLE 60S WITH VALLEY FOG HELPING OUR COLDER LOCATIONS DROP INTO THE UPPER 50S. FOR TUESDAY AND INTO TUESDAY NIGHT SCATTERED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE...MAINLY ACROSS OUR SOUTHERN TIER ...ASSOCIATED WITH THE BOUNDARY. THE FRONT SHOULD WEAKEN AND DRIFT FURTHER SOUTH WEDNESDAY MAKING CONVECTION LESS OF A THREAT. HOWEVER ...THE SOMEWHAT COOLER AND DRIER AIR WILL ALSO BE LESS OF A FACTOR AS THE WEEK WEARS ON WITH RIDGING BUILDING IN ALOFT AND SFC HIGH PRESSURE SLIDING EAST. CONVECTION RETURNS TO THE PICTURE IN THE SOUTHWEST FRIDAY AND SPREADS NORTHEAST DURING THE WEEKEND IN ADVANCE OF A WEAKENING COLD FRONT FROM THE NORTHWEST. UNCERTAINTY WITH THIS DYING BOUNDARY IN THE AREA THROUGH THE WEEKEND WILL NECESSITATE A CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH MONDAY. TEMPERATURES FROM THE MET MOS WERE FAVORED THROUGH THE FORECAST PERIOD WITH SOME ADDITIONAL ADJUSTMENT UPWARDS FOR DAILY MAXIMUMS. SINCE THE LATEST FRONTAL BOUNDARY NOW APPEARS TO BE STALLING OVER OUR SOUTHERN COUNTIES...HAVE RAISED POPS FOR TONIGHT THROUGH TUESDAY NIGHT...MAINLY IN THE TIER OF COUNTIES ALONG THE TENNESSEE BORDER. THIS STILL LEFT ME AT ABOUT HALF OF THE MET POPS...MOST SIMILAR TO THE MAV NUMBERS. WEDNESDAY AND WEDNESDAY NIGHT STILL LOOK DRY. AS FOR THE GFE/IFPS GRIDS...POPULATED WITH THE ETA12 FOR WINDS AND DEWPOINTS THROUGH 84 HOURS. THE DEWPOINTS CAME IN MUCH TOO HIGH FROM THE START AND THIS CONTINUED INTO TUESDAY...ADJUSTED THESE DOWN AND MADE THE USUAL TWEAKS FOR THE AFTERNOON MIX DOWN. WINDS CAME IN PRETTY GOOD WITH JUST SOME DIURNAL ADJUSTMENT NEEDED. THE REST OF THE TEMPERATURE GRIDS WERE IN GREAT SHAPE WITH THE MAIN CHANGES ONES THAT CONTINUED THE TREND OF BACKING OFF ON THE COOL NIGHTS AND INCLUDED RAISING MAXES A DEGREE OR TWO THROUGH THE WEEK. DUE TO THE BOUNDARY SETTING UP JUST TO THE SOUTH...HAD TO REDRAW THE SKY COVER AND POP GRIDS...THOUGH IN SOME CASES WAS ABLE TO PULL THE EXISTING GRID NORTHWARD AND ACHIEVE THE SAME EFFECT. ALSO ADDED A FEW SPRINKLES TO THE GRIDS FOR THIS EVENING AND OVERNIGHT...EXPECTING THE CURRENT SCATTERED SHOWERS AND THUNDERSTORMS ALONG THE BOUNDARY TO DIE OUT WITH THE LOSS OF DAYTIME HEATING. 1050 AM EDT MON AUG 22 2005 CURRENT FORECAST IS IN GOOD SHAPE. UPDATED TO ADD AN ISOLATED CHANCE OF SHOWERS AND THUNDERSTORMS...AS THE LATEST NAM AND RUC MODELS SHOW A SHORTWAVE MOVING ACROSS THE SOUTHWESTERN PORTION OF THE CWA DURING THE AFTERNOON AND EARLY EVENING HOURS. UPDATE ALREADY OUT. 325 AM EDT MON AUG 22 2005 SHORT TERM (TODAY THROUGH WEDNESDAY NIGHT)... THE HIGH PRESSURE OVER MANITOBA CONTINUES TO PUSH THE COLD FRONT THROUGH THE AREA. THE AIR BEHIND THE COLD FRONT IS MUCH DRIER WITH DEWPOINTS IN THE MID 50S RATHER THAN THE 70S THAT PERSISTED OVER THE AREA LATE LAST WEEK. THERE MAY BE SOME PATCHES OF MIST THIS MORNING NEAR SUNRISE...MOSTLY IN THE SOUTHERN PORTION OF THE AREA WHERE THE DEWPOINTS ARE STILL IN THE MID 60S. THERE IS AN MCC OVER SOUTHERN ILLINOIS AND WESTERN KENTUCKY. THIS MCC HAS BEEN MOVING SLOWLY TO THE EAST DURING THE EVENING. SOME OF THE CIRRUS BLOW OFF FROM THE THUNDERSTORMS HAS BEEN MOVING INTO THE FORECAST AREA. WHATS LEFT OF THE MCC LOOKS LIKE IT WILL BE PASSING JUST TO THE SOUTH OF THE FORECAST AREA OVER NORTHERN TENNESSEE ON MONDAY EVENING. THIS WILL ALSO BRING AN INCREASE TO THE CLOUDINESS FOR MONDAY EVENING AND TUESDAY MORNING. AFTER THIS PASSES...THERE REALLY IS NOT MUCH THREAT OF ANY WEATHER UNTIL THE WEEKEND. THE MODELS ARE TRYING TO SHOW A WEAK DISTURBANCE COMING THROUGH OF TUESDAY. NO ONE IN THE SURROUNDING OFFICES GAVE THIS MUCH CREDENCE...SO I CONTINUED WITH THE NO PRECIPITATION FORECAST FOR TUESDAY THAT WAS PUT OUT ON DAY SHIFT SUNDAY. THE MOS TEMPERATURE FORECAST LOOKED PRETTY GOOD. THE FORECAST TEMPS REFLECT A BLEND OF THE GFS...NAM AND NGM MOS. THE NEW RUN DID NOT DROP MIN TEMPS QUITE SO LOW FOR MONDAY OR TUESDAY NIGHT. EXTENDED (THURSDAY THROUGH SUNDAY) THE DRY PERIOD WILL CONTINUE AS THE AREA WILL BE DOMINATED BY HIGH PRESSURE. ON SATURDAY AND SUNDAY THERE WILL BE A WEAK FRONT WHICH WILL BE MOVING INTO THE AREA. NCEP FRONTAL PROGS ARE SHOWING THIS FRONT STALLING AND WASHING OUT OVER THE AREA. THIS BOUNDARY SHOULD BE ENOUGH TO KICK OFF SOME ISOLATED CONVECTION ON SATURDAY AND THEN SOME SCATTERED CONVECTION ON SUNDAY. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ RAY ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 500 PM EDT MON AUG 22 2005 .DISCUSSION... 20Z SFC ANALYSIS SHOWS THE CORE OF THE HIGH PRESSURE LOCATED OVER THE GREAT LAKES REGION WITH A SECONDARY...OR TERTIARY...COLD FRONT PRESSING SOUTH INTO NORTHERN KENTUCKY. ALONG THIS BOUNDARY A LINE OF SCATTERED TO BROKEN CONVECTIONS HAS BROKEN OUT...THE STRONGEST OF THESE LIKELY CONTAINING SMALL HAIL AND GUSTY WINDS. JUST TO THE SOUTH OF THIS...AN AREA OF SPRINKLES AND VIRGA IS DRIFTING THROUGH SOUTHEAST KENTUCKY. DESPITE THE FRONT TO THE NORTH THE DEWPOINTS TODAY WERE ABOUT 10 DEGREES LOWER THAN YESTERDAY. WITH TEMPS A GOOD 5 DEGREES OR SO COOLER...BUT SOME CREDIT FOR THIS MUST GO TO THE HIGH AND...NOW INCREASINGLY...MID LEVEL CLOUDS THAT PLAGUED US FOR MUCH OF THE DAY. THE MODELS CONTINUE TO BE IN GOOD AGREEMENT WITH THE MAIN FEATURES AFFECTING THE LONGWAVE PATTERN FOR MOST OF THE WEEK AS A MINI OMEGA BLOCK SETS UP OVER NORTHEAST CANADA. THE QUEBEC CLOSED LOW WILL ONLY SLOWLY PIVOT EAST SENDING ITS AXIS THROUGH KENTUCKY DURING THE DAY WEDNESDAY. AHEAD OF THIS...MINOR WAVES WILL MOVE OUT OF THE SOUTHERN PLAINS AND PASS OVER KENTUCKY ENHANCING THE PRECIPITATION POTENTIAL OF A RELATIVELY DRY FRONTAL BOUNDARY THAT SETTLES INTO SOUTHERN KENTUCKY AND NORTHERN TENNESSEE. A RIDGE WILL BUILD INTO THE REGION IT IS WAKE BEFORE FLATTENING OUT TO END THE WORK WEEK. MEANWHILE ...A LESS WELL HANDLED UPPER LOW WILL SLOWLY ROLL EAST THROUGH SOUTHWEST AND CENTRAL CANADA ALSO STALLING AS IT APPROACHES HUDSON BAY. THE SFC FEATURES ASSOCIATED WITH THIS UPPER LOW WILL LIKEWISE ENTER THE OHIO VALLEY AND STALL OUT NEAR KENTUCKY FOR THE WEEKEND. SENSIBLE WEATHER WILL FEATURE A WEST TO EAST BAND OF SCATTERED SHOWERS AND THUNDERSTORMS DISSIPATING AS IT SINKS THROUGH NORTHERN KENTUCKY. OUT AHEAD OF THIS BOUNDARY POCKETS OF SPRINKLES WILL BE FOUND FOR THE FIRST PART OF THE NIGHT. OTHERWISE...CLEARING SKIES TO THE NORTH WILL COMBINE WITH SOME CAA TO SEND TEMPERATURES INTO THE LOWER 60S AND UPPER 50S BY MORNING. TO THE SOUTH SOME DIMINISHMENT OF THE CLOUDS AND ADVECTION WILL ALSO DROP TEMPS INTO THE LOWER AND MIDDLE 60S WITH VALLEY FOG HELPING OUR COLDER LOCATIONS DROP INTO THE UPPER 50S. FOR TUESDAY AND INTO TUESDAY NIGHT SCATTERED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE...MAINLY ACROSS OUR SOUTHERN TIER ...ASSOCIATED WITH THE BOUNDARY. THE FRONT SHOULD WEAKEN AND DRIFT FURTHER SOUTH WEDNESDAY MAKING CONVECTION LESS OF A THREAT. HOWEVER ...THE SOMEWHAT COOLER AND DRIER AIR WILL ALSO BE LESS OF A FACTOR AS THE WEEK WEARS ON WITH RIDGING BUILDING IN ALOFT AND SFC HIGH PRESSURE SLIDING EAST. CONVECTION RETURNS TO THE PICTURE IN THE SOUTHWEST FRIDAY AND SPREADS NORTHEAST DURING THE WEEKEND IN ADVANCE OF A WEAKENING COLD FRONT FROM THE NORTHWEST. UNCERTAINTY WITH THIS DYING BOUNDARY IN THE AREA THROUGH THE WEEKEND WILL NECESSITATE A CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH MONDAY. TEMPERATURES FROM THE MET MOS WERE FAVORED THROUGH THE FORECAST PERIOD WITH SOME ADDITIONAL ADJUSTMENT UPWARDS FOR DAILY MAXIMUMS. SINCE THE LATEST FRONTAL BOUNDARY NOW APPEARS TO BE STALLING OVER OUR SOUTHERN COUNTIES...HAVE RAISED POPS FOR TONIGHT THROUGH TUESDAY NIGHT...MAINLY IN THE TIER OF COUNTIES ALONG THE TENNESSEE BORDER. THIS STILL LEFT ME AT ABOUT HALF OF THE MET POPS...MOST SIMILAR TO THE MAV NUMBERS. WEDNESDAY AND WEDNESDAY NIGHT STILL LOOK DRY. AS FOR THE GFE/IFPS GRIDS...POPULATED WITH THE ETA12 FOR WINDS AND DEWPOINTS THROUGH 84 HOURS. THE DEWPOINTS CAME IN MUCH TOO HIGH FROM THE START AND THIS CONTINUED INTO TUESDAY...ADJUSTED THESE DOWN AND MADE THE USUAL TWEAKS FOR THE AFTERNOON MIX DOWN. WINDS CAME IN PRETTY GOOD WITH JUST SOME DIURNAL ADJUSTMENT NEEDED. THE REST OF THE TEMPERATURE GRIDS WERE IN GREAT SHAPE WITH THE MAIN CHANGES ONES THAT CONTINUED THE TREND OF BACKING OFF ON THE COOL NIGHTS AND INCLUDED RAISING MAXES A DEGREE OR TWO THROUGH THE WEEK. DUE TO THE BOUNDARY SETTING UP JUST TO THE SOUTH...HAD TO REDRAW THE SKY COVER AND POP GRIDS...THOUGH IN SOME CASES WAS ABLE TO PULL THE EXISTING GRID NORTHWARD AND ACHIEVE THE SAME EFFECT. ALSO ADDED A FEW SPRINKLES TO THE GRIDS FOR THIS EVENING AND OVERNIGHT...EXPECTING THE CURRENT SCATTERED SHOWERS AND THUNDERSTORMS ALONG THE BOUNDARY TO DIE OUT WITH THE LOSS OF DAYTIME HEATING. && .PREV DISCUSSION... 1050 AM EDT MON AUG 22 2005 CURRENT FORECAST IS IN GOOD SHAPE. UPDATED TO ADD AN ISOLATED CHANCE OF SHOWERS AND THUNDERSTORMS...AS THE LATEST NAM AND RUC MODELS SHOW A SHORTWAVE MOVING ACROSS THE SOUTHWESTERN PORTION OF THE CWA DURING THE AFTERNOON AND EARLY EVENING HOURS. UPDATE ALREADY OUT. 325 AM EDT MON AUG 22 2005 SHORT TERM (TODAY THROUGH WEDNESDAY NIGHT)... THE HIGH PRESSURE OVER MANITOBA CONTINUES TO PUSH THE COLD FRONT THROUGH THE AREA. THE AIR BEHIND THE COLD FRONT IS MUCH DRIER WITH DEWPOINTS IN THE MID 50S RATHER THAN THE 70S THAT PERSISTED OVER THE AREA LATE LAST WEEK. THERE MAY BE SOME PATCHES OF MIST THIS MORNING NEAR SUNRISE...MOSTLY IN THE SOUTHERN PORTION OF THE AREA WHERE THE DEWPOINTS ARE STILL IN THE MID 60S. THERE IS AN MCC OVER SOUTHERN ILLINOIS AND WESTERN KENTUCKY. THIS MCC HAS BEEN MOVING SLOWLY TO THE EAST DURING THE EVENING. SOME OF THE CIRRUS BLOW OFF FROM THE THUNDERSTORMS HAS BEEN MOVING INTO THE FORECAST AREA. WHATS LEFT OF THE MCC LOOKS LIKE IT WILL BE PASSING JUST TO THE SOUTH OF THE FORECAST AREA OVER NORTHERN TENNESSEE ON MONDAY EVENING. THIS WILL ALSO BRING AN INCREASE TO THE CLOUDINESS FOR MONDAY EVENING AND TUESDAY MORNING. AFTER THIS PASSES...THERE REALLY IS NOT MUCH THREAT OF ANY WEATHER UNTIL THE WEEKEND. THE MODELS ARE TRYING TO SHOW A WEAK DISTURBANCE COMING THROUGH OF TUESDAY. NO ONE IN THE SURROUNDING OFFICES GAVE THIS MUCH CREDENCE...SO I CONTINUED WITH THE NO PRECIPITATION FORECAST FOR TUESDAY THAT WAS PUT OUT ON DAY SHIFT SUNDAY. THE MOS TEMPERATURE FORECAST LOOKED PRETTY GOOD. THE FORECAST TEMPS REFLECT A BLEND OF THE GFS...NAM AND NGM MOS. THE NEW RUN DID NOT DROP MIN TEMPS QUITE SO LOW FOR MONDAY OR TUESDAY NIGHT. EXTENDED (THURSDAY THROUGH SUNDAY) THE DRY PERIOD WILL CONTINUE AS THE AREA WILL BE DOMINATED BY HIGH PRESSURE. ON SATURDAY AND SUNDAY THERE WILL BE A WEAK FRONT WHICH WILL BE MOVING INTO THE AREA. NCEP FRONTAL PROGS ARE SHOWING THIS FRONT STALLING AND WASHING OUT OVER THE AREA. THIS BOUNDARY SHOULD BE ENOUGH TO KICK OFF SOME ISOLATED CONVECTION ON SATURDAY AND THEN SOME SCATTERED CONVECTION ON SUNDAY. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ GREIF ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 300 PM EDT MON AUG 22 2005 .SHORT TERM (TONIGHT AND TUESDAY)... A FEW SHOWERS ARE CURRENTLY DEVELOPING ALONG A SOUTHWARD PROPAGATING WEAK FRONTAL BOUNDARY LOCATED NEAR THE OHIO RIVER. ANOTHER WEAK DISTURBANCE IS TRAVERSING THE TENNESSEE VALLEY...EMBEDDED WITHIN THE MID-LEVEL ZONAL FLOW SOUTH OF THE GREAT LAKES EASTWARD MOVING TROUGH. MAIN FORECAST CONCERN IS CHANCE OF PRECIPITATION. RUC MODEL INDICATING AXIS OF LOWER LIFTED INDICES ALONG OHIO RIVER VALLEY...JUST SOUTH OF DRIER DEWPOINTS ACROSS CENTRAL INDIANA. ALTHOUGH ACARS IS SHOWING MID-LEVEL WARMING...SEEMS TO BE ENOUGH ELEVATED INSTABILITY AVAILABLE TO PRODUCE THESE ISOLATED SHOWERS/STORMS...WHICH ARE CO-LOCATED WITH 850MB HIGHER DEWPOINTS. WITH HIGHER SHEAR STAYING NORTH (40 KTS DEEP LAYER SHEAR PER KIND VWP)...WEAK SHEAR LOCALLY AND DRIER AIR WORKING IN MAY RESULT IN A FEW ISOLATED MICROBURSTS TO AROUND 50 MPH. HOWEVER THIS WILL BE A DIURNAL THREAT...SO WILL KEEP SLIGHTS IN OVER NORTHERN CWA...AND WILL TAPER OFF AFTER SUNSET. ANOTHER UPPER-LEVEL DISTURBANCE IS PROGGED TO MOVE FROM SOUTHERN MISSOURI TO WESTERN KY BY MORNING. WITH LOW-LEVEL BOUNDARIES STILL AROUND...AND HIGHER DEWPOINTS STILL PRESENT OVER SOUTHERN CWA...HAVE INSERTED LOW CHC POPS ACROSS SOUTHERN/SOUTHWESTERN FA THROUGH TUESDAY AFTERNOON. DRIER AIR...BY THIS TIME WILL HAVE WORKED INTO NORTHERN HALF OF CWA...SO SEE NO REASON TO HAVE PRECIP THERE. LOWER 850MB TEMPS AND 1000-850MB THICKNESSES RUNNING LOWER TUESDAY MORNING SO HAVE LOW 80S IN MOST PLACES...WITH MID 80S SOUTHWEST. DEPENDING ON CLOUD COVER...MAY HAVE TO TWEAK SW HIGHS DOWN A TAD FOR TUESDAY. AL .LONG TERM (TUESDAY NIGHT THROUGH MONDAY)... ECMWF SHOWS AN UPPER SHORTWAVE TROF AND ASSOCIATED VORT CRUISING ALONG THE CANADIAN BORDER MID-WEEK AND THEN SLIPPING NORTHEAST INTO CANADA OVER THE WEEKEND AS RIDGING BUILDS OVER THE SOUTHEAST UNITED STATES. IT KEEPS THE ASSOCIATED SURFACE COLD FRONT OFF TO OUR WEST AND NORTH AS IT RUNS INTO HIGH PRESSURE OVER THE EASTERN UNITED STATES. THE GEM DEPICTS THE UPPER SHORTWAVE MUCH STRONGER AND BRINGS ITS INFLUENCES MUCH FARTHER SOUTH...INTO THE OHIO VALLEY FRIDAY NIGHT. HAVE NOTICED THE GEM OVER-DO A FEW SYSTEMS PREVIOUSLY THIS SUMMER. THE NOGAPS DEPICTS THESE FEATURES AS WELL AND IS ACTUALLY A NICE COMPROMISE BETWEEN THE ECMWF AND GEM WITH THE POTENCY OF THE UPPER SYSTEM AND HAS SIMILAR TIMING BRINGING IT INTO THE GREAT LAKES FRIDAY NIGHT/EARLY SATURDAY. AGAIN IT KEEPS THE ASSOCIATED COLD FRONT PRIMARILY TO OUR WEST AND NORTH. UPPER RIDGING WILL KEEP THE REGION DRY THROUGH AT LEAST MID-WEEK. ISOLATED THUNDER WILL BE POSSIBLE IN THE WEST FRIDAY AFTERNOON AS THAT FRONT APPROACHES...AND SMALL CHANCES OF THUNDER WILL REMAIN INTO SATURDAY AS THE FRONT TRIES TO MOVE EASTWARD AND WE ARE IN A WARM MOIST AIR MASS. SUNDAY INTO MONDAY THE EASTERN RIDGE MAY BUILD WESTWARD A BIT AND HELP TO KEEP THUNDERSTORM CHANCES LOW ENOUGH TO PRECLUDE MENTION IN THE FORECAST FOR NOW...THOUGH CAN'T TOTALLY RULE OUT A POP-UP AFTERNOON STORM. 13 && LMK WATCHES/WARNINGS/ADVISORIES... .IN...NONE. .KY...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 1050 AM EDT MON AUG 22 2005 .DISCUSSION... CURRENT FORECAST IS IN GOOD SHAPE. UPDATED TO ADD AN ISOLATED CHANCE OF SHOWERS AND THUNDERSTORMS...AS THE LATEST NAM AND RUC MODELS SHOW A SHORTWAVE MOVING ACROSS THE SOUTHWESTERN PORTION OF THE CWA DURING THE AFTERNOON AND EARLY EVENING HOURS. UPDATE ALREADY OUT. && .PREV DISCUSSION... 325 AM EDT MON AUG 22 2005 SHORT TERM (TODAY THROUGH WEDNESDAY NIGHT)... THE HIGH PRESSURE OVER MANITOBA CONTINUES TO PUSH THE COLD FRONT THROUGH THE AREA. THE AIR BEHIND THE COLD FRONT IS MUCH DRIER WITH DEWPOINTS IN THE MID 50S RATHER THAN THE 70S THAT PERSISTED OVER THE AREA LATE LAST WEEK. THERE MAY BE SOME PATCHES OF MIST THIS MORNING NEAR SUNRISE...MOSTLY IN THE SOUTHERN PORTION OF THE AREA WHERE THE DEWPOINTS ARE STILL IN THE MID 60S. THERE IS AN MCC OVER SOUTHERN ILLINOIS AND WESTERN KENTUCKY. THIS MCC HAS BEEN MOVING SLOWLY TO THE EAST DURING THE EVENING. SOME OF THE CIRRUS BLOW OFF FROM THE THUNDERSTORMS HAS BEEN MOVING INTO THE FORECAST AREA. WHATS LEFT OF THE MCC LOOKS LIKE IT WILL BE PASSING JUST TO THE SOUTH OF THE FORECAST AREA OVER NORTHERN TENNESSEE ON MONDAY EVENING. THIS WILL ALSO BRING AN INCREASE TO THE CLOUDINESS FOR MONDAY EVENING AND TUESDAY MORNING. AFTER THIS PASSES...THERE REALLY IS NOT MUCH THREAT OF ANY WEATHER UNTIL THE WEEKEND. THE MODELS ARE TRYING TO SHOW A WEAK DISTURBANCE COMING THROUGH OF TUESDAY. NO ONE IN THE SURROUNDING OFFICES GAVE THIS MUCH CREDENCE...SO I CONTINUED WITH THE NO PRECIPITATION FORECAST FOR TUESDAY THAT WAS PUT OUT ON DAY SHIFT SUNDAY. THE MOS TEMPERATURE FORECAST LOOKED PRETTY GOOD. THE FORECAST TEMPS REFLECT A BLEND OF THE GFS...NAM AND NGM MOS. THE NEW RUN DID NOT DROP MIN TEMPS QUITE SO LOW FOR MONDAY OR TUESDAY NIGHT. EXTENDED (THURSDAY THROUGH SUNDAY) THE DRY PERIOD WILL CONTINUE AS THE AREA WILL BE DOMINATED BY HIGH PRESSURE. ON SATURDAY AND SUNDAY THERE WILL BE A WEAK FRONT WHICH WILL BE MOVING INTO THE AREA. NCEP FRONTAL PROGS ARE SHOWING THIS FRONT STALLING AND WASHING OUT OVER THE AREA. THIS BOUNDARY SHOULD BE ENOUGH TO KICK OFF SOME ISOLATED CONVECTION ON SATURDAY AND THEN SOME SCATTERED CONVECTION ON SUNDAY. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ 25 ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 916 PM EDT MON AUG 22 2005 .SHORT TERM (REST OF TONIGHT)... JUST A QUICK UPDATE TO THE ZONE FORECAST THIS EVENING TO REFLECT THE SCATTERED TO BROKEN CI LAYER CROSSING THE CWA AND THE PRESENCE OF SCATTERED MID LEVEL CU WHICH THE IAD 00Z SOUNDING SHOW TO BE AT ABOUT 9K FT. THESE CLOUD APPEAR TO BE ASSOCIATED WITH THE RIGHT FRONT ENTRANCE OF H25 JET WHICH STRETCHES FROM THE NORTHERN MID ATLANTIC REGION NORTHEASTWARD ACROSS EASTERN NEW ENGLAND. 18Z ETA AND 23Z RUC PROJECT THAT THE JET WILL LIFT TO THE NORTH BETWEEN 03Z AND 06Z...AND MOSTLY CLEAR SKY CONDITIONS IN PA AND SOUTHERN OH WILL MOVE INTO THE REGION...BEFORE MIDNIGHT ACROSS THE NORTHERN CWA AND AFTER MIDNIGHT ACROSS THE SOUTHERN CWA. ALSO TWEAKED WIND SPEEDS UPWARD 2 TO 4 KT THIS EVENING...AS SFC PRESSURE GRADIENT CURRENTLY SUPPORTING NW OT N WINDS OF 5 TO 10 KT. EXPECT THESE WINDS TO BECOME LIGHT AND VARIABLE AFTER 06Z...WHEN SFC RIDGING INCREASES SLIGHTLY FROM THE NORTHWEST. && .PREVIOUS DISCUSSION...ISSUED 230 PM EDT MON AUG 22 2005... SHORT TERM...TONIGHT THROUGH TUESDAY... WATER VAPOR LOOP SHOWS AN AMPLIFIED UPPER TROUGH DOMINATING THE GREAT LAKES...NEW ENGLAND AND BUILDING INTO THE MID ATLANTIC REGION. A REINFORCING WAVE IS PUSHING INTO PENNSYLVANIA. RELATIVELY WEAKER WAVES ARE FOUND WITHIN THE MEAN FLOW FROM THE PLAINS INTO THE LOWER MID ATLANTIC. UPPER LEVEL RIDGES DOMINATE THE GULF STATES AND ROCKIES. ACARS 400-250MB WIND OBSERVATIONS REVEAL A 100KT JET ACROSS THE LOWER GREAT LAKES INTO CENTRAL PENNSYLVANIA. 11Z SURFACE ANALYSIS PLACES A 1012MB CYCLONE OVER SOUTH CAROLINA...ALONG A STALLING BOUNDARY WHICH EXTENDS WEST THROUGH THE PLAINS. A SECONDARY COLD/STATIONARY FRONT STRETCHES FROM THE EASTERN GREAT LAKES SOUTHWEST THEN WEST INTO THE NORTHERN PLAINS. A TROUGH WAS SITUATED OFF THE NEW ENGLAND AND MID ATLANTIC COAST. THE AFOREMENTIONED TROUGH OFF THE ATLANTIC COAST IS AN INDICATION THAT THE DEEP LAYER MOISTURE HAS BEEN SHUNTED EAST. BOTH SATELLITE DERIVED AND GPS SATELLITE SENSORS INDICATE THAT PRECIPITABLE WATER VALUES HAVE FALLEN CLOSE TO AND BELOW ONE INCH ACROSS THE AREA. EXPECTING CUMULUS TO DECAY DIURNALLY THIS EVENING. WINDS WILL ALSO SLACKEN AS THE NOCTURNAL INVERSION BEGINS TO DEVELOP WITH SUNSET. THE COMBINATION OF AN ENERGETIC WAVE ACROSS THE NORTHERN GREAT LAKES SWINGING INTO THE NORTHERN MID ATLANTIC TOMORROW MORNING...AND WEAK WAVES ACROSS THE TENNESSEE VALLEY BEING DRAWN NORTHEAST WITHIN THE MEAN FLOW...SHOULD ENCOURAGE AN INCREASE IN MID AND UPPER LEVEL MOISTURE LATE TONIGHT AND TUESDAY. GIVEN THE CURRENT MOISTURE CONTENT OF THE ATMOSPHERE...WILL BE HARD TO PRECIPITATE ACROSS MOST OF THE REGION. PLACED A 20 PERCENT POP ACROSS THE SOUTHERN AND SOUTHEAST ZONES...AS THIS AREA IS CLOSER TO THE DEEP LAYER MOISTURE WHICH SHOULD BE ADVECTING NORTHWARD...AND TO THE DYNAMICS OF THE NORTHERN MID ATLANTIC WAVE AND RIGHT ENTRANCE OF THE UPPER LEVEL JET. FORECASTED STABILITY INDICES RULE OUT THUNDER. GIVEN THIS SETUP...EXPECTING CLOUD CANOPY TO BE THICKEST ACROSS THE SOUTHERN AND SOUTHEAST ZONES BY AFTERNOON...ENCOURAGING TEMPERATURES IN THE NORTHERN ZONES TO APPROACH OR EXCEED THOSE FURTHER SOUTH. CONFIDENCE OF OPAQUENESS OF CLOUDS IS NOT HIGH AT THIS TIME...SO KEPT TEMPERATURES IN THE LOWER 80S ACROSS THE SOUTHERN ZONES...WHICH MAY HAVE TO BE LOWERED. ALTHOUGH THE COOL CANADIAN AIRMASS IS ON OUR DOORSTEP ACROSS THE GREAT LAKES...THE UPPER LEVEL TROUGH WILL PREVENT THE HEIGHT RISES NECESSARY FOR THIS SYSTEM TO CONTINUE TO BUILD SOUTHEAST INTO THE AREA DURING THE SHORT TERM. AVIATION...SCATTERED CLOUDS WITHIN THE LOWER/MIDDLE/AND UPPER LEVELS THROUGH THE TAF PERIOD (LOWER LEVEL CU WILL DIMINISH THEN REDEVELOP DIURNALLY...WHILE A GRADUAL INCREASE IN MID TO UPPER LEVEL MOISTURE IS EXPECTED ESPECIALLY AFTER DAYBREAK). GUSTY NORTHWEST WINDS (EXCEPT AT KCHO) WILL QUICKLY DIMINISH WITH SUNSET (REMAINING A BIT STRONGER FROM THE NORTH WITHIN THE POTOMAC RIVER VALLEY NEAR KDCA OVERNIGHT). WINDS ARE EXPECTED TO REMAIN RELATIVELY LIGHTER TUESDAY. MARINE...NORTHWEST FLOW AROUND 15 KTS LATE THIS AFTERNOON... DIMINISHING WITH SUNSET. WATER LEVELS ARE CURRENTLY AT PREDICTED VALUES. LONG TERM... A TRANQUIL STRING OF DAYS ACRS CWFA. TUE NGT PROVIDES ONLY CHC FOR PCPN...AND THAT WUD BE A SLIM ONE. IT WUD APPR THAT WV FM OK WL BE SHUNTED EWD BY POS TILTED H5 TROF OVR NE CONUS...AND HV DIFFICULTY SPREADING PCPN TOO MUCH FRTHR N THAN A CHO-EZF-NHK LN. CONFIDENCE ON EVEN LINE NOT THE GREATEST...AND THUS ONLY INCL 20 POPS FOR SRN CNTYS TUE NGT. THRAFTR...FCST WL BE DRY TIL DAY 6-7...WHEN A CDFNT PROGGED TO SETTLE ACRS CWFA. IN BTWN...LG AREA OF HIPRES WL SETTLE ACRS NE CONUS...PROVIDING SEASONABL TEMPS...LWR DEWPTS...AND MOSUN DAYS/MOCLR NGTS. CLDS IN GRIDS IN SCT RNG...LIKELY TO BOUNCE BTWN PTCLDY AND MOCLR. PTCLDY SKIES W/IN REASON BY FRI AS HIPRES SHIFTS OFFSHR AND RTN FLOW ENSUES...BRINGING MSTR BACK TO RGN. WENT CLSR TO MAV POPS /ALTHO EVEN THEY WERE UNDERCUT/...SO USED MAV TMP GDNC AS BASE FOR MAX/MINS. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SHORT TERM...SMITH md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 340 PM EDT MON AUG 22 2005 .SHORT TERM...TONIGHT AND TUESDAY 12Z RAOBS/WATER VAPOR LOOP SHOW UPPER LOW OVER QUEBEC...WITH A SHORTWAVE SWINGING THROUGH NORTHERN ONTARIO DOWN THE BACK SIDE OF IT. SURFACE ANALYSIS SHOWS HIGH PRESSURE BUILDING DOWN ACROSS THE MINNESOTA BOUNDARY WATERS...WITH CYCLONIC FLOW HOLDING ON ACROSS THE CENTRAL GREAT LAKES. VIS SATELLITE SHOWS A SOLID SC DECK ACROSS LOWER MICHIGAN...ALTHOUGH WITH ANY WEAK REFLECTIVITIES ON THE APX RADAR DRYING UP AS THEY DOWNSLOPE INTO THE SAGINAW VALLEY. 12Z NAM INDICATES ANOTHER SURGE OF LOW-LEVEL MOISTURE SWINGING IN WITH THE TRAILING SHORTWAVE. GFS IS DRIER AS EXPECTED...ALTHOUGH SATELLITE GOING BACK THROUGH LAST NIGHT SUPPORTS THE NAM SOLUTION. WITH ADDITIONAL MOISTURE/CLOUDS EXPECTED TO CONTINUE SOUTHWARD ACROSS THE REGION...KEPT MOSTLY CLOUDY SKIES THROUGH THE NIGHT. WINDS VEER AROUND MORE TO THE NORTH/NORTHEAST TONIGHT...WHICH SUPPORTS A BETTER CHANCE OF PRECIP ACROSS THE THUMB. EC/EXETER RADAR NOT SHOWING AS MANY LAKE EFFECT SHOWERS AS EARLIER IN THE DAY...BUT PER VIS SATELLITE IT APPEARS THAT BANDS ARE TRYING TO REORIENT. NAM SEEMED TO HAVE A GOOD HANDLE ON LOW-LEVEL CONVERGENCE EARLIER IN THE DAY...WHICH IS BRINGS INLAND ACROSS THE THUMB AS WINDS COME AROUND THIS EVENING. CONVERGENCE/OMEGA NOT QUITE AS STRONG AS EARLIER THOUGH...SO JUST KEPT THE CHANCE SHRA GOING TONIGHT. COMPETING FACTORS FOR LOWS TONIGHT...WITH UNSEASONABLE COLD THERMAL TROUGH BUT WIDESPREAD CLOUD COVER. CURRENT FORECAST LOOKS PRETTY GOOD...SIMILAR TO THOUGH A TOUCH COLDER THAN LAST NIGHT. COULD SEE SOME DIURNAL ENHANCEMENT TO CLOUD FIELDS AGAIN TUESDAY MORNING...BUT DRIER AIR WILL FILTER IN DURING THE AFTERNOON. AIRMASS MODERATES A BIT AS WELL...WITH INVERSIONS HOLDING LONGER THAN INDICATED. ALTHOUGH DRY AIR WILL BE WORKING IN...HELD ONTO CHANCE POPS THROUGH MID AFTERNOON TO ALLOW FOR A SLOWER TIMING AS IS USUALLY THE CASE IN THESE SITUATIONS. SKIES SHOULD BREAK OUT INLAND AWAY FROM THE THUMB THOUGH...WITH SOME CU PRESENT BUT OVERALL PARTLY SUNNY CONDITIONS. WITH BETTER INSOLATION AND SOME MODERATION... EXPECT HIGHS A FEW DEGREES WARMER THAN TODAY. && .LONG TERM...TUESDAY NIGHT THROUGH MONDAY CHILLY HIGH PRESSURE WILL REMAIN IN CONTROL OF THE WEATHER AROUND SE MICHIGAN TUESDAY NIGHT AND WEDNESDAY. CLEAR SKY AND COOL TEMPS WILL KEEP THINGS QUIET OVER LAND AREAS BUT THE SETUP FOR WATERSPOUTS IN LAKE ERIE STILL LOOKS GOOD, IF NOT IDEAL. THE LOW LEVEL THERMAL TROF OVER BOTH LAKE HURON AND LAKE ERIE WILL MODIFY TOWARD 10C BUT THIS WILL STILL LEAVE A LAKE TO 850 MB DELTA-T AROUND 15C IN WESTERN LAKE ERIE. FORECAST SOUNDINGS FROM THE NAM12 AND GFS SHOW INVERSION BASE ABOVE 850 MB AND CLOUD DEPTH CLOSE TO 10 KFT WHEN FACTORING IN CLOUD TOPS IN THE SOUNDING. PROBABLY THE MOST IMPORTANT ASPECT IS THE EASTERLY FLOW THAT IS SET UP BY THE SURFACE RIDGE DRIFTING TO OUR NORTH. IT IS BETTER TO HAVE THE RIDGE OVERHEAD BUT THE EASTERLY FLOW WILL AT LEAST GET CONVECTIVE ELEMENTS HEADING INTO THE WESTERN BASIN. THE LIMITING FACTOR MAY BE CAUSED BY THE NORTHWARD PLACEMENT OF THE RIDGE AXIS FORCING THE LAND BREEZE CIRCULATION CLOSER TO THE SOUTH SHORELINE. AT THIS POINT, THE NAM12 IS OUR BEST ESTIMATE AND IT STILL KEEPS THE SOUTH PORTIONS OF MONROE COUNTY CLOSE TO THE ACTION. USING THIS, WE'LL ADD A CHANCE OF SPOUTS TO THE LAKE ERIE NEARSHORE AND KEEP A MENTION IN THE HWO. DAYTIME HEATING WILL REVERSE THE LAND TO LAKE BREEZE CIRCULATIONS DURING THE DAYTIME ON WEDNESDAY. THIS WILL CAUSE SLIGHTLY COOLER TEMPS WITH ONSHORE FLOW IN THE THUMB BUT OTHERWISE NO SIGNIFICANT WEATHER WEDNESDAY INTO THURSDAY. MODEL AGREEMENT IS GOOD REGARDING SURFACE HIGH PRESSURE SLIDING TO OUR EAST ON THURSDAY WITH A LOW OVER CENTRAL CANADA. IT IS THIS LOW THAT WILL BE THE SUBJECT OF EXPECTATIONS IN THE GREAT LAKES FOR AT LEAST THE BEGINNING OF THE WEEKEND. THE LATEST EURO AND GFS RUNS ARE TRENDING TOWARD A BLOCKY UPPER AIR PATTERN BY FRIDAY WHICH IS SLOWING DOWN THE PROGRESSION OF ANY SURFACE FEATURES INTO SE MICHIGAN. THE ECMWF AND UKMET ARE PARTICULARLY AGGRESSIVE WITH THIS SCENARIO WHILE THE GFS IS WEAKER AND THE CANADIAN MORE OPEN AND PROGRESSIVE. THE CANADIAN AND GFS KEEP AN OUTSIDE CHANCE OF SHOWERS IN OUR AREA ON FRIDAY AND SATURDAY, MORE DUE TO WARM ADVECTION AS THE GFS SLIDES A WEAK SHORT WAVE UNDER THE BLOCK AND OVER THE GREAT LAKES. THE 12Z RUN THEN WASHES OUT THE SURFACE FRONT BY SATURDAY EVENING. THIS IS A PRETTY SMALL SCALE FEATURE FOR ANY RELIABLE PREDICTABILITY FOR FRONTAL TIMING. ON THE LARGE SCALE, THE GFS ENSEMBLE SUPPORTS MORE OF A EURO MODEL SOLUTION TO THE UPPER AIR PATTERN THAT ALSO SUPPORTS RAIN CHANCES ON SATURDAY BUT WITH THE COLD FRONT STAYING TO OUR WEST UNTIL SUNDAY. OUR GOING FORECAST COVERS THE TIMING UNCERTAINTY IN THIS REGARD WITH A CHANCE OF SHOWERS AND STORMS ON SUNDAY AS WELL. PLAN TO START MONDAY OFF DRY WITH SLIGHTLY ABOVE NORMAL TEMPS AS THIS SYSTEM SHOULD BE ABLE TO EXIT EAST OF THE REGION BY THEN. && .PREV DISCUSSION... (ISSUED 125 PM EDT MON AUG 22 2005) AVIATION... VISIBLE SATELLITE/METARS SHOW A PRETTY SOLID CLOUD DECK ACROSS LOWER MICHIGAN...PREDOMINATELY VFR BUT WITH A FEW MVFR REPORTS. WILL KEEP THE TAFS VFR AS CIG HEIGHTS SHOULD SLOWLY CONTINUE TO LIFT WITH ADDITIONAL HEATING. AS IT TYPICAL...12Z NAM SHOWS MUCH MORE LOW-LEVEL MOISTURE THAN THE GFS...ALTHOUGH THIS TIME THE NAM SOLUTION LOOKS MORE REASONABLE. WIDESPREAD MVFR CLOUDS APPARENT ON SATELLITE ACROSS EASTERN ONTARIO FROM JAMES BAY TO LAKE SUPERIOR. THESE CLOUDS ARE CURRENTLY MAKING A FAIR SOUTHWARD PROGRESS...AND AS WINDS TURN MORE TO THE NORTH THIS MOISTURE SHOULD CONTINUE DOWN ACROSS THE CWA. WINDS SHOULD EVEN BE A TOUCH NORTHEAST ACROSS THE NORTHERN GREAT LAKES...WITH STRAIGHT IF NOT CYCLONIC FLOW ACROSS THE REGION /NOT ANTICYCLONIC/. WILL HOLD ONTO A BROKEN DECK THROUGH THE NIGHT...RATHER THAN SCATTER OUT THIS EVENING WITH LOSS OF DIURNAL ENHANCEMENT. DROPPED CIGS TO MVFR OVERNIGHT BASED ON UPSTREAM TRENDS. SURFACE HIGH BUILDS IN ON TUESDAY...WITH DRYING AND INVERSION HEIGHTS REALLY CRASHING DOWN DURING THE AFTERNOON. HOWEVER WILL HOLD ONTO CLOUDS THROUGH THE TAF PERIOD/18Z...ESPECIALLY WITH A DIURNAL PUSH DURING THE MORNING. UPDATE...1117 AM EDT MON AUG 22 2005 VIS SATELLITE SHOW CLOUDS PROGRESSING SOUTHWARD ACROSS THE CWA...WITH DIURNAL HEATING HELPING TO FILL IN/ENHANCE THE CU/SC. MOSTLY CLOUD LOOKS ON TRACK FOR THE BULK OF THE CWA...JUST STICKING WITH PARTLY SUNNY IN THE FAR SOUTH. 14Z TAMDAR OBSERVED SOUNDINGS/12Z RUC FORECAST SOUNDINGS SHOW BETTER LOW-LEVEL MOISTURE ACROSS THE NORTHERN CWA...AS WOULD BE EXPECTED BASED ON SATELLITE IMAGERY. WOULD NOT BE SURPRISED TO SEE SOME LIGHT RAIN SHOWERS AS WE CONTINUE TO FURTHER STEEPEN THE LOW-LEVEL LAPSE RATES THROUGH THE DAY. NOT QUITE ENOUGH FOR MEASURABLE PRECIP...BUT WILL ADD A MENTION OF SPRINKLES TO THE NORTHERN CWA. EXCEPTION IS STILL ACROSS THE THUMB...WHERE WINDS ARE EXPECTED TO TURN MORE TO THE NORTH THIS AFTERNOON BRINGING ADDITIONAL LAKE EFFECT POTENTIAL INTO THE PICTURE. EC/EXETER RADAR SHOWS A COUPLE BANDS OF ECHOES STREAMING OFF LAKE HURON. 12Z NAM PICKS UP ON AN AREA OF LOW-LEVEL CONVERGENCE IN THIS AREA...WHICH IT THEN SHIFTS DOWN ACROSS THE THUMB BY EVENING AS WINDS VEER AROUND TO THE NORTH OVER THE LAKE. SCATTERED SHOWERS STILL LOOK GOOD FOR THIS AREA. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON UNTIL MIDNIGHT TONIGHT. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM/AVIATION...BRAVENDER LONG TERM....BT mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 125 PM EDT MON AUG 22 2005 .AVIATION... VISIBLE SATELLITE/METARS SHOW A PRETTY SOLID CLOUD DECK ACROSS LOWER MICHIGAN...PREDOMINATELY VFR BUT WITH A FEW MVFR REPORTS. WILL KEEP THE TAFS VFR AS CIG HEIGHTS SHOULD SLOWLY CONTINUE TO LIFT WITH ADDITIONAL HEATING. AS IT TYPICAL...12Z NAM SHOWS MUCH MORE LOW-LEVEL MOISTURE THAN THE GFS...ALTHOUGH THIS TIME THE NAM SOLUTION LOOKS MORE REASONABLE. WIDESPREAD MVFR CLOUDS APPARENT ON SATELLITE ACROSS EASTERN ONTARIO FROM JAMES BAY TO LAKE SUPERIOR. THESE CLOUDS ARE CURRENTLY MAKING A FAIR SOUTHWARD PROGRESS...AND AS WINDS TURN MORE TO THE NORTH THIS MOISTURE SHOULD CONTINUE DOWN ACROSS THE CWA. WINDS SHOULD EVEN BE A TOUCH NORTHEAST ACROSS THE NORTHERN GREAT LAKES...WITH STRAIGHT IF NOT CYCLONIC FLOW ACROSS THE REGION /NOT ANTICYCLONIC/. WILL HOLD ONTO A BROKEN DECK THROUGH THE NIGHT...RATHER THAN SCATTER OUT THIS EVENING WITH LOSS OF DIURNAL ENHANCEMENT. DROPPED CIGS TO MVFR OVERNIGHT BASED ON UPSTREAM TRENDS. SURFACE HIGH BUILDS IN ON TUESDAY...WITH DRYING AND INVERSION HEIGHTS REALLY CRASHING DOWN DURING THE AFTERNOON. HOWEVER WILL HOLD ONTO CLOUDS THROUGH THE TAF PERIOD/18Z...ESPECIALLY WITH A DIURNAL PUSH DURING THE MORNING. && .UPDATE...1117 AM EDT MON AUG 22 2005 VIS SATELLITE SHOW CLOUDS PROGRESSING SOUTHWARD ACROSS THE CWA...WITH DIURNAL HEATING HELPING TO FILL IN/ENHANCE THE CU/SC. MOSTLY CLOUD LOOKS ON TRACK FOR THE BULK OF THE CWA...JUST STICKING WITH PARTLY SUNNY IN THE FAR SOUTH. 14Z TAMDAR OBSERVED SOUNDINGS/12Z RUC FORECAST SOUNDINGS SHOW BETTER LOW-LEVEL MOISTURE ACROSS THE NORTHERN CWA...AS WOULD BE EXPECTED BASED ON SATELLITE IMAGERY. WOULD NOT BE SURPRISED TO SEE SOME LIGHT RAIN SHOWERS AS WE CONTINUE TO FURTHER STEEPEN THE LOW-LEVEL LAPSE RATES THROUGH THE DAY. NOT QUITE ENOUGH FOR MEASURABLE PRECIP...BUT WILL ADD A MENTION OF SPRINKLES TO THE NORTHERN CWA. EXCEPTION IS STILL ACROSS THE THUMB...WHERE WINDS ARE EXPECTED TO TURN MORE TO THE NORTH THIS AFTERNOON BRINGING ADDITIONAL LAKE EFFECT POTENTIAL INTO THE PICTURE. EC/EXETER RADAR SHOWS A COUPLE BANDS OF ECHOES STREAMING OFF LAKE HURON. 12Z NAM PICKS UP ON AN AREA OF LOW-LEVEL CONVERGENCE IN THIS AREA...WHICH IT THEN SHIFTS DOWN ACROSS THE THUMB BY EVENING AS WINDS VEER AROUND TO THE NORTH OVER THE LAKE. SCATTERED SHOWERS STILL LOOK GOOD FOR THIS AREA. && .SHORT TERM...MONDAY AND MONDAY NIGHT...ISSUED AT 339 AM EDT DOWNSLOPING IS REALLY CUTTING INTO CLOUD COVER THIS MORNING AND WILL HAVE TO ADJUST FORECAST TO BE MORE OPTIMISTIC THIS MORNING...BEFORE DIURNAL MAX IN CLOUD COVER KICKS IN MIDDAY. WILL ALSO REMOVE SLIGHT CHANCE OF SHOWERS FROM THE CWA TODAY GIVEN TRENDS...BUT WILL KEEP A MENTION OF SHOWERS IN THE EASTERN THUMB WHERE LAKE EFFECT INFLUENCE MAY STILL BE FELT. THIS WILL BE THE SAME OVERNIGHT AS WELL. ONLY ADJUST TO TEMPERATURES WAS TO UP HIGHS TODAY A FEW DEGREES FROM ABOUT M 59 SOUTH...DUE TO DOWNSLOPING NORTHWEST FLOW AND A BIT MORE SUNSHINE THIS MORNING. STILL...TEMPERATURES WILL BE WELL BELOW NORMAL FOR A CHANGE...GENERALLY RANGING IN THE LOWER 70S -VS- LOWER 80S...WHICH ARE NORMAL FOR LATE AUGUST. WILL LET GALE WARNING DROP OVER NORTHERN LAKE HURON AS WINDS HAVE GENERALLY HELD SUSTAINED AT 25 KNOTS...WITH GUSTS TO 30 KNOTS OR SO. NEARSHORE SMALL CRAFT ADVISORIES ARE IN GOOD SHAPE. EVEN IF WINDS GO JUST BELOW THE 15-25 KNOT THRESHOLD...WAVES WILL STEADILY BUILD TO 3-5 FEET OR BETTER WITH PERSISTENT NORTHWEST-NORTH FLOW. && .LONG TERM...TUESDAY THROUGH SUNDAY...ISSUED AT 339 AM EDT RESIDUAL LAKE EFFECT ACTIVITY WILL COME TO AN END TUESDAY MORNING WITH DRIER AIR FILTERING FROM UPSTREAM AND ALOFT COMBINING WITH WARMING 850MB TEMPS. RUC13 AND NAM12 ARE FAIRLY SIMILAR IN THIS REGARD WITH QPF AND LOW LEVEL OMEGA FIELDS DECREASING TOWARD 16Z. THEREFORE IMPROVING LAKE CONDITIONS WILL EQUATE TO IMPROVEMENTS FURTHER INLAND. CU RULE CONTINUES TO SUPPORT SCT CONDITIONS (PERHAPS 1-2 HOURS OF BKN) YET THE DRIER AIR ALOFT SEEN IN PROFILES WILL BE SURE TO MIX OUT QUICKLY. BASED ON BUFKIT HOURLY MIXING LAYER HEIGHTS...WE TAP JUST ABOVE 800MB WHICH WOULD EQUATE TO MAX TEMPS INTO THE LOWER HALF OF THE 70S CWA-WIDE (A BIT COOLER NEAR LAKE HURON BUT NOT BY MUCH WITH LAKE TEMPS INTO THE UPPER 60S AND LOWER 70S. AS INDICATED IN THE PREVIOUS AFD...TUESDAY NIGHT AND WEDNESDAY MORNING COULD PROVE TO BE QUITE INTERESTING OVER THE LAKES. SURFACE HIGH SETTLES OVER THE LAKES REGION WITH MOSTLY CLEAR SKIES AND LIGHT WINDS. LOOKS LIKE A GOOD SET UP FOR LAND BREEZE CIRCULATIONS OVERNIGHT AS THE NAM12 AND RUC13 DEPICTS THIS VERY WELL. NAM12 CONTINUES TO ADVERTISE QUITE A CONVERGENCE BAND ACROSS LAKE ERIE LATE TUESDAY NIGHT AND WEDNESDAY MORNING TO IMPACT SOUTHERN MONROE COUNTY TOWARD SUNRISE...AND A MUCH WEAKER ONE OVER SOUTHERN LAKE HURON. THE BEST WATERSPOUT POTENTIAL APPEARS TO BE OVER WESTERN LAKE ERIE ON WEDNESDAY MORNING GIVEN THE CONVECTIVE BAND (PROBABLY JUST TOWERING CU...NOT EVEN SHOWERS). WILL CONTINUE HIGHLIGHT THIS WITHIN THE HWO AT THIS TIME. THEN BIG BUBBLE WITH RIDGE AT ALL LEVELS THROUGH THURSDAY WITH CURRENT TEMPERATURES IN THE GRIDS/FORECAST LOOKING GOOD AND IN CLOSE AGREEMENT WITH THE MEX VALUES. LOOKING FURTHER IN THE EXTENDED...IT BECOMES QUITE COMPLICATED WITH ANOTHER WAVE COMING DOWN ACROSS ALASKA INTO DIGGING TROF ACROSS THE PACIFIC NORTHWEST. THE NAM/GFS AT F84 AGREE WITH THE POTENT WAVE SETTING UP FOR AN ACTIVE DAY ACROSS THE NORTHERN PLAINS WITH THE CANADIAN ABOUT 6-12 HOURS SLOWER. THIS WILL HAVE IMPLICATIONS FOR OUR END OF THE WEEK AND WEEKEND FORECAST WITH A PROLONGED SOUTHWEST FLOW REGIME BEHIND DEPARTING SURFACE HIGH. WITH CONVECTION EMBEDDED WITH THE NUMERICAL SOLUTIONS AND LACK OF UPPER AIR DATA OVER THE NORTH PACIFIC...WE WILL LEAVE THE CHANCE FOR CONVECTION AS IS WITH THE CURRENT FORECAST. BASED ON THIS MORNINGS WATER VAPOR LOOP...THE CANADIAN AND THE DGEX MIGHT HAVE THE RIGHT IDEA WITH TAKING THE LEAD WAVE TO IMPACT THE LAKES ON FRIDAY AND A NARROW RIDGE OF HIGH PRESSURE FOR THE START OF THE WEEKEND (GFS LOOKS TOO AMPLIFIED WITH CONVECTIVE FEEDBACK ISSUES). && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...SMALL CRAFT ADVISORY...LHZ421 UNTIL 6 PM MONDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON-LHZ464 UNTIL MIDNIGHT TUESDAY. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....BRAVENDER UPDATE.......BRAVENDER SHORT TERM...DG LONG TERM....BGM HTTP://WEATHER.GOV/DETROIT mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1117 AM EDT MON AUG 22 2005 .UPDATE... VIS SATELLITE SHOW CLOUDS PROGRESSING SOUTHWARD ACROSS THE CWA...WITH DIURNAL HEATING HELPING TO FILL IN/ENHANCE THE CU/SC. MOSTLY CLOUD LOOKS ON TRACK FOR THE BULK OF THE CWA...JUST STICKING WITH PARTLY SUNNY IN THE FAR SOUTH. 14Z TAMDAR OBSERVED SOUNDINGS/12Z RUC FORECAST SOUNDINGS SHOW BETTER LOW-LEVEL MOISTURE ACROSS THE NORTHERN CWA...AS WOULD BE EXPECTED BASED ON SATELLITE IMAGERY. WOULD NOT BE SURPRISED TO SEE SOME LIGHT RAIN SHOWERS AS WE CONTINUE TO FURTHER STEEPEN THE LOW-LEVEL LAPSE RATES THROUGH THE DAY. NOT QUITE ENOUGH FOR MEASURABLE PRECIP...BUT WILL ADD A MENTION OF SPRINKLES TO THE NORTHERN CWA. EXCEPTION IS STILL ACROSS THE THUMB...WHERE WINDS ARE EXPECTED TO TURN MORE TO THE NORTH THIS AFTERNOON BRINGING ADDITIONAL LAKE EFFECT POTENTIAL INTO THE PICTURE. EC/EXETER RADAR SHOWS A COUPLE BANDS OF ECHOES STREAMING OFF LAKE HURON. 12Z NAM PICKS UP ON AN AREA OF LOW-LEVEL CONVERGENCE IN THIS AREA...WHICH IT THEN SHIFTS DOWN ACROSS THE THUMB BY EVENING AS WINDS VEER AROUND TO THE NORTH OVER THE LAKE. SCATTERED SHOWERS STILL LOOK GOOD FOR THIS AREA. && .AVIATION...725 AM EDT MON AUG 22 2005 CEILINGS TO FLUTTER JUST ABOVE VFR TODAY FNT/MBS AS STRATUS AND STRATO-CU CONTINUE TO ADVECT DOWN INTO THE AREA IN COOL NORTHWEST FLOW. THESE CONDITIONS WILL ALSO MAKE IT INTO DTW/DET EVENTUALLY. WILL CARRY THE 3500-4000FT BKN-OVC CEILINGS INTO THE MID EVENING BEFORE SCATTERING ALL AREAS OUT. WINDS NORTHWEST GOING TO THE NORTH TONIGHT. && .SHORT TERM...MONDAY AND MONDAY NIGHT...ISSUED AT 339 AM EDT DOWNSLOPING IS REALLY CUTTING INTO CLOUD COVER THIS MORNING AND WILL HAVE TO ADJUST FORECAST TO BE MORE OPTIMISTIC THIS MORNING...BEFORE DIURNAL MAX IN CLOUD COVER KICKS IN MIDDAY. WILL ALSO REMOVE SLIGHT CHANCE OF SHOWERS FROM THE CWA TODAY GIVEN TRENDS...BUT WILL KEEP A MENTION OF SHOWERS IN THE EASTERN THUMB WHERE LAKE EFFECT INFLUENCE MAY STILL BE FELT. THIS WILL BE THE SAME OVERNIGHT AS WELL. ONLY ADJUST TO TEMPERATURES WAS TO UP HIGHS TODAY A FEW DEGREES FROM ABOUT M 59 SOUTH...DUE TO DOWNSLOPING NORTHWEST FLOW AND A BIT MORE SUNSHINE THIS MORNING. STILL...TEMPERATURES WILL BE WELL BELOW NORMAL FOR A CHANGE...GENERALLY RANGING IN THE LOWER 70S -VS- LOWER 80S...WHICH ARE NORMAL FOR LATE AUGUST. WILL LET GALE WARNING DROP OVER NORTHERN LAKE HURON AS WINDS HAVE GENERALLY HELD SUSTAINED AT 25 KNOTS...WITH GUSTS TO 30 KNOTS OR SO. NEARSHORE SMALL CRAFT ADVISORIES ARE IN GOOD SHAPE. EVEN IF WINDS GO JUST BELOW THE 15-25 KNOT THRESHOLD...WAVES WILL STEADILY BUILD TO 3-5 FEET OR BETTER WITH PERSISTENT NORTHWEST-NORTH FLOW. && .LONG TERM...TUESDAY THROUGH SUNDAY...ISSUED AT 339 AM EDT RESIDUAL LAKE EFFECT ACTIVITY WILL COME TO AN END TUESDAY MORNING WITH DRIER AIR FILTERING FROM UPSTREAM AND ALOFT COMBINING WITH WARMING 850MB TEMPS. RUC13 AND NAM12 ARE FAIRLY SIMILAR IN THIS REGARD WITH QPF AND LOW LEVEL OMEGA FIELDS DECREASING TOWARD 16Z. THEREFORE IMPROVING LAKE CONDITIONS WILL EQUATE TO IMPROVEMENTS FURTHER INLAND. CU RULE CONTINUES TO SUPPORT SCT CONDITIONS (PERHAPS 1-2 HOURS OF BKN) YET THE DRIER AIR ALOFT SEEN IN PROFILES WILL BE SURE TO MIX OUT QUICKLY. BASED ON BUFKIT HOURLY MIXING LAYER HEIGHTS...WE TAP JUST ABOVE 800MB WHICH WOULD EQUATE TO MAX TEMPS INTO THE LOWER HALF OF THE 70S CWA-WIDE (A BIT COOLER NEAR LAKE HURON BUT NOT BY MUCH WITH LAKE TEMPS INTO THE UPPER 60S AND LOWER 70S. AS INDICATED IN THE PREVIOUS AFD...TUESDAY NIGHT AND WEDNESDAY MORNING COULD PROVE TO BE QUITE INTERESTING OVER THE LAKES. SURFACE HIGH SETTLES OVER THE LAKES REGION WITH MOSTLY CLEAR SKIES AND LIGHT WINDS. LOOKS LIKE A GOOD SET UP FOR LAND BREEZE CIRCULATIONS OVERNIGHT AS THE NAM12 AND RUC13 DEPICTS THIS VERY WELL. NAM12 CONTINUES TO ADVERTISE QUITE A CONVERGENCE BAND ACROSS LAKE ERIE LATE TUESDAY NIGHT AND WEDNESDAY MORNING TO IMPACT SOUTHERN MONROE COUNTY TOWARD SUNRISE...AND A MUCH WEAKER ONE OVER SOUTHERN LAKE HURON. THE BEST WATERSPOUT POTENTIAL APPEARS TO BE OVER WESTERN LAKE ERIE ON WEDNESDAY MORNING GIVEN THE CONVECTIVE BAND (PROBABLY JUST TOWERING CU...NOT EVEN SHOWERS). WILL CONTINUE HIGHLIGHT THIS WITHIN THE HWO AT THIS TIME. THEN BIG BUBBLE WITH RIDGE AT ALL LEVELS THROUGH THURSDAY WITH CURRENT TEMPERATURES IN THE GRIDS/FORECAST LOOKING GOOD AND IN CLOSE AGREEMENT WITH THE MEX VALUES. LOOKING FURTHER IN THE EXTENDED...IT BECOMES QUITE COMPLICATED WITH ANOTHER WAVE COMING DOWN ACROSS ALASKA INTO DIGGING TROF ACROSS THE PACIFIC NORTHWEST. THE NAM/GFS AT F84 AGREE WITH THE POTENT WAVE SETTING UP FOR AN ACTIVE DAY ACROSS THE NORTHERN PLAINS WITH THE CANADIAN ABOUT 6-12 HOURS SLOWER. THIS WILL HAVE IMPLICATIONS FOR OUR END OF THE WEEK AND WEEKEND FORECAST WITH A PROLONGED SOUTHWEST FLOW REGIME BEHIND DEPARTING SURFACE HIGH. WITH CONVECTION EMBEDDED WITH THE NUMERICAL SOLUTIONS AND LACK OF UPPER AIR DATA OVER THE NORTH PACIFIC...WE WILL LEAVE THE CHANCE FOR CONVECTION AS IS WITH THE CURRENT FORECAST. BASED ON THIS MORNINGS WATER VAPOR LOOP...THE CANADIAN AND THE DGEX MIGHT HAVE THE RIGHT IDEA WITH TAKING THE LEAD WAVE TO IMPACT THE LAKES ON FRIDAY AND A NARROW RIDGE OF HIGH PRESSURE FOR THE START OF THE WEEKEND (GFS LOOKS TOO AMPLIFIED WITH CONVECTIVE FEEDBACK ISSUES). && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...SMALL CRAFT ADVISORY...LHZ421 UNTIL 6 PM MONDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON-LHZ464 UNTIL MIDNIGHT TUESDAY. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ UPDATE.......BRAVENDER AVIATION.....DG SHORT TERM...DG LONG TERM....BGM HTTP://WEATHER.GOV/DETROIT mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1100 AM EDT MON AUG 22 2005 .UPDATE... 15Z WATER VAPOR AND RUC UPPER AIR ANALYSIS CONTINUE TO SHOW A STRONG MIDLEVEL LOW OVER SOUTHCENTRAL QUEBEC. UPPER RIDGING BUILDING OVER THE NORTHERN PLAINS AND CENTRAL CANADA...HOWEVER STILL SEEING SOME CYCLONIC FLOW OVER CENTRAL AND EASTERN LAKE SUPERIOR. SHOWERS/SPRINKLES ACROSS THE NORTHCENTRAL AND EASTERN U.P. FROM THIS MORNING HAVE COME TO AN END AND PARTLY SUNNY SKIES HAVE DEVELOPED. PREVIOUS THINKING THAT ABUNDANT 925 TO 700 MB MOISTURE ON BACK SIDE OF UPPER LOW WOULD ROTATE BACK INTO THE CENTRAL AND EASTERN U.P DURING THE AFTERNOON STILL LOOKS ON TRACK. UPDATE SKYCOVER GRIDS TO MORE ACCURATELY REFLECT THIS MOISTURE SURGE. LATEST NAM AND RUC RUNS HAVE BACKED OFF A BIT ON THE AMOUNT OF MOISTURE THAT REACHES THE KEWEENAW...BUT STILL BELIEVE SOME INCREASE IN CLOUDCOVER WILL OCCUR FOR AT LEAST A FEW HOURS THIS AFTERNOON...ESPECIALLY FROM KCMX UP TO COPPER HARBOR. HAVE SEEN SOME DIURNAL CU DEVELOP ACROSS THE WESTERN U.P. BUT FEEL THAT THIS CLOUDCOVER SHOULD THIN DURING THE MID TO LATE AFTERNOON. FOR THE FAR EAST THIS AFTERNOON...BACKED THE PRECIP TO JUST AN ISOLATED CHANCE OF A BRIEF SHOWER AS LOW LEVEL MOISTURE COMES BACK IN. GENERALLY THINK BEST CHANCES WOULD BE ACROSS LUCE COUNTY BUT WOULD NOT BE SURPRISED TO SEE A DRY SCENARIO FOR ALL AREAS DEVELOP. LATEST RADAR IMAGERY FROM CANADIAN SITE WGJ (MONTREAL RIVER) SHOWS LITTLE TO ANY PRECIP UNDER THIS CLOUD SHIELD...BUT LIKELY STILL SEEING SOME MIST OR VERY LIGHT SPRINKLES NOT DETECTED BY RADAR (BASED ON EARLIER OBSERVATIONS FROM 12Z.) GOING TEMPERATURES LOOKED FINE WITH MIDDLE TO UPPER 60S WEST AND LOWER TO MIDDLE 60S ACROSS THE EAST UNDER MORE CERTAIN CLOUDCOVER AND 850MB TEMPS IN THE 4 TO 5 C RANGE. && .PREVIOUS DISCUSSION... MAIN FCST ISSUES ARE LINGERING SPRINKLES/-SHRA TODAY...FROST POTENTIAL TONIGHT AND THEN ONLY TEMPS THROUGH MIDWEEK AS DRY AIRMASS SETTLES OVER THE AREA FOR A FEW DAYS. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW AN UNSEASONABLY STRONG MIDLEVEL LOW OVER SW QUEBEC WITH UPPER GREAT LAKES REGION STILL UNDER INFLUENCE OF ITS CIRCULATION. UPSTREAM...RIDGE IS SLOWLY PROGRESSING ACROSS SASKATCHEWAN/MANITOBA. IR AND 11-3.9MICRON SATELLITE IMAGERY SHOW FAIRLY SHARP BACK EDGE TO STRATOCU MOVING S TOWARD NE MN AND NW/NCNTRL LAKE SUPERIOR. ANOTHER LARGE AREA OF STRATOCU WRAPPING AROUND MIDLEVEL LOW IS DROPPING SSW FROM JAMES BAY TOWARD ERN LAKE SUPERIOR. 00Z SOUNDINGS SHOW 850MB TEMPS OF 4/3C AT KINL/CWPL RESPECTIVELY WITH INVERSION BASE BTWN 825 AND 840MB. WITH SFC WATER TEMP AROUND 17C...OVERWATER INSTABILITY IS SUFFICIENT FOR LAKE EFFECT -SHRA/SPRINKLES...ESPECIALLY NCNTRL UPPER MI THANKS TO LONGER FETCH AND LARGER POOL OF WARMER WATER OVER CNTRL/ERN LAKE. PCPN HAS BEEN INCREASING IN INTENSITY THE LAST COUPLE OF HRS AS WE APPROACH THE MORE FAVORABLE LOW END OF DIURNAL TEMP CYCLE. 00Z NAM INITIALIZED 850MB TEMPS UPSTREAM ABOUT 2C TOO WARM. ALTHOUGH GFS HAS BETTER INITIALIZATION...IT STILL HAS 850MB TEMPS MODERATING TO 6-8C TODAY...SIMILAR TO NAM. SO...TREND WILL BE FOR DIMINISHING LAKE EFFECT CLOUDINESS...ESPECIALLY OVER THE W WHERE NAM/GFS SHOW MUCH DRIER AIR. THIS LOOKS REASONABLE BASED ON UPSTREAM CONDITIONS EARLY THIS MORNING. MEANWHILE...GFS/NAM/RUC SUGGEST 850-900MB WINDS WILL VEER TO A MORE NNE DIRECTION TODAY WHICH WILL BRING STRATOCU NE OF LAKE SUPERIOR PER SATELLITE IMAGERY INTO THE E AND PROBABLY CNTRL SECTIONS AS WELL. SO WILL GO WITH A MORE PESSIMISTIC SKY COVER FCST THERE THAN OVER THE W. AS FOR PCPN...LAKE EFFECT -SHRA/SPRINKLES OCCURRING OVER NCNTRL/ERN FCST AREA SHOULD END BY NOON DUE TO COMBINATION OF DAYTIME HEATING AND MODERATING 850MB TEMPS. HOWEVER...CAN'T RULE OUT SOME SPRINKLES DURING THE AFTN AS INSTABILITY DEVELOPS OVER THE LAND. W WILL REMAIN DRY. HAVE LOWERED TEMPS A COUPLE OF DEGREES OVER THE E WITH EXPECTED CLOUD COVER. UPPER 60S LOOK FINE OVER THE SW WHERE MORE SUN WILL BE THE RULE. TONIGHT...UPSTREAM MIDLEVEL RIDGE DRIFTS E WITH ASSOCIATED SFC HIGH SETTLING OVER WRN UPPER MI. SHOULD BE NEARLY IDEAL RADIATIONAL COOLING CONDITIONS OVER THE W WITH CLR SKIES AND LIGHT/CALM WIND. MIN PRECIPITABLE WATER HAS SHIFTED SLIGHTLY W WITH LATEST MODEL RUNS...SO COLDEST TEMPS WILL PROBABLY OCCUR TO THE W OF UPPER MI. NONETHELESS...WITH PRECIPITABLE WATER BLO A 1/2INCH...EXPECT TEMPS TO FALL EASILY BLO GUIDANCE NUMBERS...POSSIBLY INTO THE MID 30S IN THE TYPICAL COLD SPOTS. A SPOT OR TWO MAY EVEN SLIP TO FREEZING. UPSTREAM TEMPS EARLY THIS MORNING SUPPORT THE EXPECTED CHILL AS READINGS OVER WRN ONTARIO HAVE FALLEN THRU LATE AFTN SFC DWPT READINGS DUE TO DRY COLUMN. CURRENT TEMPS AT THE FEW AVAILABLE OBSERVATION SITES RANGE FROM THE MID 30S TO MID 40S WITH SEVERAL MORE HRS YET BEFORE SUNRISE. WILL CONTINUE TO MENTION PATCHY/AREAS OF FROST IN GRIDS/ZFP AND HWO IN THE INTERIOR SW. DAYSHIFT WILL PROBABLY NEED TO ISSUE ADVY FOR SW AREAS IF FCST REMAINS ON TRACK. WILL LIKELY SEE SOME PATCHY FOG NEAR LAKES/STREAMS/SWAMPY AREAS (IT IS THAT TIME OF YEAR)...BUT SINCE IT SHOULD BE SHALLOW AND VERY LIMITED IN COVERAGE...WILL NOT MENTION IN FCST. TO THE E...WEAK GRADIENT NRLY FLOW WILL KEEP TEMPS WARM ENOUGH TO PREVENT FROST E OF A KSAW TO KIMT LINE. IN ADDITION...GFS/NAM SUGGEST STRATOCU MAY LINGER FOR A GOOD PORTION OF THE NIGHT. TUE/WED WILL BE DOMINATED BY SFC HIGH PRES AND MIDLEVEL RIDGING OVER THE UPPER GREAT LAKES REGION. DEEP DRY AIRMASS OVER THE AREA SUGGESTS LITTLE IN THE WAY OF CLOUDS AND ALSO A LARGE DIURNAL TEMP SWING FROM TUE AFTN TO TUE NIGHT TO WED AFTN. MIXING TO 850MB ON NAM/GFS FCST SOUNDINGS SUPPORTS HIGHS IN THE 70-75 RANGE ON TUE... JUST SLIGHTLY COOLER NEAR LAKE SUPERIOR WITH LAKE BREEZE DOMINATING THE BOUNDARY LAYER WIND FLOW. WITH WATER TEMP AROUND 70F OVER THE BAY OF GREEN BAY/NRN LAKE MI...LAKE BREEZE WILL NOT REALLY PROVIDE ANY COOLING NEAR THE LAKE THERE. ALTHOUGH AIRMASS WILL BE MODERATING...TEMPS SHOULD CRASH AGAIN TUE NIGHT WITH DEEP DRY AIRMASS FIRMLY OVER THE AREA (PRECIPITABLE WATER GENERALLY UNDER 1/2INCH). SFC HIGH PRES WILL ALSO STILL BE CLOSE ENOUGH TO MINIMIZE RETURN FLOW...EXCEPT PERHAPS OVER THE FAR W. WILL THUS GO BLO ALL GUIDANCE WITH COOLEST TEMPS IN THE INTERIOR CNTRL/E (AROUND 40F). NOT OUT OF THE QUESTION THAT PATCHY FROST MAY NEED TO BE CONSIDERED. TEMPS SHOULD RISE QUICKLY WED MORNING. UNDER FULL SUN...MIXING TO 850-800MB ON FCST SOUNDINGS SUGGESTS HIGHS 75-80. MIDLEVEL RIDGING SLIPS E WED NIGHT/THU...AND ATTENTION TURNS TOWARD A SHORTWAVE GFS/NAM SHOW LIFTING TOWARD THE WRN LAKES THU MORNING WELL AHEAD OF NEXT SIGNIFICANT SHORTWAVE TROF MOVING THRU THE NRN ROCKIES. GIVEN SLOW EXIT OF ERN TROF...HAVE A FEELING RIDGE WILL STILL BE MORE FIRMLY IN PLACE FARTHER W THAN MODELS INDICATE. STRENGTH OF UPSTREAM POTENT TROF WELL TO THE W HEADING ACROSS THE NRN ROCKIES WOULD ALSO SUGGEST MORE RIDGING HERE. WILL THUS CONTINUE TO HOLD OFF SHRA/TSRA CHANCES UNTIL THU NIGHT PER GOING FCST. EXPECT HIGHS ON THU AROUND 80 IN MOST LOCATIONS. && .MQT...WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...MROCZKA PREVIOUS DISCUSSION...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 750 AM EDT MON AUG 22 2005 .UPDATE... SAT LOOP INDICATING THAT SURGE OF DRY AIR UPSTREAM IS PRESSING STEADILY INTO THE AREA. KEWEENAW PENINSULA ALREADY SEEING MAINLY CLEAR SKIES...AND DESPITE CURRENT LGT PCPN OVR NCNTRL COUNTIES...THINK A QUICKER CLEARING TREND IS LIKELY. COMPLICATING MATTERS IS ABUNDANCE OF H9-H7 MOISTURE PER 00Z MOOSONEE ONTARIO SOUNDING (S TIP OF JAMES BAY) THAT IS RE-ENTERING FAR E LK SUPERIOR. BOTH RUC AND NAM INDICATE THIS SLUG OF MOISTURE WILL SURGE BACK INTO CWA BY MIDDAY AND INTO THE AFTN. SO...LOOKS LIKE A BRIEF CLEARING TREND THEN BACK INTO THE CLOUDS LATER ON. TRIED TO SHOW THIS IN GRIDS. OTHERWISE...UPDATE ENDED AM PCPN QUICKER OVR W 2/3 ZONES...AND KEPT PCPN IN ALL DAY IN EAST AS MOISTURE PUSHES BACK IN WHILE A SLIGHTLY CYCLONIC NW FLOW OFF LK SUPERIOR LINGERS THROUGH MOST OF AFTN. NO CHANGES TO TEMPS/WINDS. && .DISCUSSION... MAIN FCST ISSUES ARE LINGERING SPRINKLES/-SHRA TODAY...FROST POTENTIAL TONIGHT AND THEN ONLY TEMPS THROUGH MIDWEEK AS DRY AIRMASS SETTLES OVER THE AREA FOR A FEW DAYS. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW AN UNSEASONABLY STRONG MIDLEVEL LOW OVER SW QUEBEC WITH UPPER GREAT LAKES REGION STILL UNDER INFLUENCE OF ITS CIRCULATION. UPSTREAM...RIDGE IS SLOWLY PROGRESSING ACROSS SASKATCHEWAN/MANITOBA. IR AND 11-3.9MICRON SATELLITE IMAGERY SHOW FAIRLY SHARP BACK EDGE TO STRATOCU MOVING S TOWARD NE MN AND NW/NCNTRL LAKE SUPERIOR. ANOTHER LARGE AREA OF STRATOCU WRAPPING AROUND MIDLEVEL LOW IS DROPPING SSW FROM JAMES BAY TOWARD ERN LAKE SUPERIOR. 00Z SOUNDINGS SHOW 850MB TEMPS OF 4/3C AT KINL/CWPL RESPECTIVELY WITH INVERSION BASE BTWN 825 AND 840MB. WITH SFC WATER TEMP AROUND 17C...OVERWATER INSTABILITY IS SUFFICIENT FOR LAKE EFFECT -SHRA/SPRINKLES...ESPECIALLY NCNTRL UPPER MI THANKS TO LONGER FETCH AND LARGER POOL OF WARMER WATER OVER CNTRL/ERN LAKE. PCPN HAS BEEN INCREASING IN INTENSITY THE LAST COUPLE OF HRS AS WE APPROACH THE MORE FAVORABLE LOW END OF DIURNAL TEMP CYCLE. 00Z NAM INITIALIZED 850MB TEMPS UPSTREAM ABOUT 2C TOO WARM. ALTHOUGH GFS HAS BETTER INITIALIZATION...IT STILL HAS 850MB TEMPS MODERATING TO 6-8C TODAY...SIMILAR TO NAM. SO...TREND WILL BE FOR DIMINISHING LAKE EFFECT CLOUDINESS...ESPECIALLY OVER THE W WHERE NAM/GFS SHOW MUCH DRIER AIR. THIS LOOKS REASONABLE BASED ON UPSTREAM CONDITIONS EARLY THIS MORNING. MEANWHILE...GFS/NAM/RUC SUGGEST 850-900MB WINDS WILL VEER TO A MORE NNE DIRECTION TODAY WHICH WILL BRING STRATOCU NE OF LAKE SUPERIOR PER SATELLITE IMAGERY INTO THE E AND PROBABLY CNTRL SECTIONS AS WELL. SO WILL GO WITH A MORE PESSIMISTIC SKY COVER FCST THERE THAN OVER THE W. AS FOR PCPN...LAKE EFFECT -SHRA/SPRINKLES OCCURRING OVER NCNTRL/ERN FCST AREA SHOULD END BY NOON DUE TO COMBINATION OF DAYTIME HEATING AND MODERATING 850MB TEMPS. HOWEVER...CAN'T RULE OUT SOME SPRINKLES DURING THE AFTN AS INSTABILITY DEVELOPS OVER THE LAND. W WILL REMAIN DRY. HAVE LOWERED TEMPS A COUPLE OF DEGREES OVER THE E WITH EXPECTED CLOUD COVER. UPPER 60S LOOK FINE OVER THE SW WHERE MORE SUN WILL BE THE RULE. TONIGHT...UPSTREAM MIDLEVEL RIDGE DRIFTS E WITH ASSOCIATED SFC HIGH SETTLING OVER WRN UPPER MI. SHOULD BE NEARLY IDEAL RADIATIONAL COOLING CONDITIONS OVER THE W WITH CLR SKIES AND LIGHT/CALM WIND. MIN PRECIPITABLE WATER HAS SHIFTED SLIGHTLY W WITH LATEST MODEL RUNS...SO COLDEST TEMPS WILL PROBABLY OCCUR TO THE W OF UPPER MI. NONETHELESS...WITH PRECIPITABLE WATER BLO A 1/2INCH...EXPECT TEMPS TO FALL EASILY BLO GUIDANCE NUMBERS...POSSIBLY INTO THE MID 30S IN THE TYPICAL COLD SPOTS. A SPOT OR TWO MAY EVEN SLIP TO FREEZING. UPSTREAM TEMPS EARLY THIS MORNING SUPPORT THE EXPECTED CHILL AS READINGS OVER WRN ONTARIO HAVE FALLEN THRU LATE AFTN SFC DWPT READINGS DUE TO DRY COLUMN. CURRENT TEMPS AT THE FEW AVAILABLE OBSERVATION SITES RANGE FROM THE MID 30S TO MID 40S WITH SEVERAL MORE HRS YET BEFORE SUNRISE. WILL CONTINUE TO MENTION PATCHY/AREAS OF FROST IN GRIDS/ZFP AND HWO IN THE INTERIOR SW. DAYSHIFT WILL PROBABLY NEED TO ISSUE ADVY FOR SW AREAS IF FCST REMAINS ON TRACK. WILL LIKELY SEE SOME PATCHY FOG NEAR LAKES/STREAMS/SWAMPY AREAS (IT IS THAT TIME OF YEAR)...BUT SINCE IT SHOULD BE SHALLOW AND VERY LIMITED IN COVERAGE...WILL NOT MENTION IN FCST. TO THE E...WEAK GRADIENT NRLY FLOW WILL KEEP TEMPS WARM ENOUGH TO PREVENT FROST E OF A KSAW TO KIMT LINE. IN ADDITION...GFS/NAM SUGGEST STRATOCU MAY LINGER FOR A GOOD PORTION OF THE NIGHT. TUE/WED WILL BE DOMINATED BY SFC HIGH PRES AND MIDLEVEL RIDGING OVER THE UPPER GREAT LAKES REGION. DEEP DRY AIRMASS OVER THE AREA SUGGESTS LITTLE IN THE WAY OF CLOUDS AND ALSO A LARGE DIURNAL TEMP SWING FROM TUE AFTN TO TUE NIGHT TO WED AFTN. MIXING TO 850MB ON NAM/GFS FCST SOUNDINGS SUPPORTS HIGHS IN THE 70-75 RANGE ON TUE... JUST SLIGHTLY COOLER NEAR LAKE SUPERIOR WITH LAKE BREEZE DOMINATING THE BOUNDARY LAYER WIND FLOW. WITH WATER TEMP AROUND 70F OVER THE BAY OF GREEN BAY/NRN LAKE MI...LAKE BREEZE WILL NOT REALLY PROVIDE ANY COOLING NEAR THE LAKE THERE. ALTHOUGH AIRMASS WILL BE MODERATING...TEMPS SHOULD CRASH AGAIN TUE NIGHT WITH DEEP DRY AIRMASS FIRMLY OVER THE AREA (PRECIPITABLE WATER GENERALLY UNDER 1/2INCH). SFC HIGH PRES WILL ALSO STILL BE CLOSE ENOUGH TO MINIMIZE RETURN FLOW...EXCEPT PERHAPS OVER THE FAR W. WILL THUS GO BLO ALL GUIDANCE WITH COOLEST TEMPS IN THE INTERIOR CNTRL/E (AROUND 40F). NOT OUT OF THE QUESTION THAT PATCHY FROST MAY NEED TO BE CONSIDERED. TEMPS SHOULD RISE QUICKLY WED MORNING. UNDER FULL SUN...MIXING TO 850-800MB ON FCST SOUNDINGS SUGGESTS HIGHS 75-80. MIDLEVEL RIDGING SLIPS E WED NIGHT/THU...AND ATTENTION TURNS TOWARD A SHORTWAVE GFS/NAM SHOW LIFTING TOWARD THE WRN LAKES THU MORNING WELL AHEAD OF NEXT SIGNIFICANT SHORTWAVE TROF MOVING THRU THE NRN ROCKIES. GIVEN SLOW EXIT OF ERN TROF...HAVE A FEELING RIDGE WILL STILL BE MORE FIRMLY IN PLACE FARTHER W THAN MODELS INDICATE. STRENGTH OF UPSTREAM POTENT TROF WELL TO THE W HEADING ACROSS THE NRN ROCKIES WOULD ALSO SUGGEST MORE RIDGING HERE. WILL THUS CONTINUE TO HOLD OFF SHRA/TSRA CHANCES UNTIL THU NIGHT PER GOING FCST. EXPECT HIGHS ON THU AROUND 80 IN MOST LOCATIONS. && .MQT...WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...JLA DISCUSSION...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 725 AM EDT MON AUG 22 2005 .AVIATION... CEILINGS TO FLUTTER JUST ABOVE VFR TODAY FNT/MBS AS STRATUS AND STRATO-CU CONTINUE TO ADVECT DOWN INTO THE AREA IN COOL NORTHWEST FLOW. THESE CONDITIONS WILL ALSO MAKE IT INTO DTW/DET EVENTUALLY. WILL CARRY THE 3500-4000FT BKN-OVC CEILINGS INTO THE MID EVENING BEFORE SCATTERING ALL AREAS OUT. WINDS NORTHWEST GOING TO THE NORTH TONIGHT. && .SHORT TERM...MONDAY AND MONDAY NIGHT...ISSUED AT 339 AM EDT DOWNSLOPING IS REALLY CUTTING INTO CLOUD COVER THIS MORNING AND WILL HAVE TO ADJUST FORECAST TO BE MORE OPTIMISTIC THIS MORNING...BEFORE DIURNAL MAX IN CLOUD COVER KICKS IN MIDDAY. WILL ALSO REMOVE SLIGHT CHANCE OF SHOWERS FROM THE CWA TODAY GIVEN TRENDS...BUT WILL KEEP A MENTION OF SHOWERS IN THE EASTERN THUMB WHERE LAKE EFFECT INFLUENCE MAY STILL BE FELT. THIS WILL BE THE SAME OVERNIGHT AS WELL. ONLY ADJUST TO TEMPERATURES WAS TO UP HIGHS TODAY A FEW DEGREES FROM ABOUT M 59 SOUTH...DUE TO DOWNSLOPING NORTHWEST FLOW AND A BIT MORE SUNSHINE THIS MORNING. STILL...TEMPERATURES WILL BE WELL BELOW NORMAL FOR A CHANGE...GENERALLY RANGING IN THE LOWER 70S -VS- LOWER 80S...WHICH ARE NORMAL FOR LATE AUGUST. WILL LET GALE WARNING DROP OVER NORTHERN LAKE HURON AS WINDS HAVE GENERALLY HELD SUSTAINED AT 25 KNOTS...WITH GUSTS TO 30 KNOTS OR SO. NEARSHORE SMALL CRAFT ADVISORIES ARE IN GOOD SHAPE. EVEN IF WINDS GO JUST BELOW THE 15-25 KNOT THRESHOLD...WAVES WILL STEADILY BUILD TO 3-5 FEET OR BETTER WITH PERSISTENT NORTHWEST-NORTH FLOW. && .LONG TERM...TUESDAY THROUGH SUNDAY...ISSUED AT 339 AM EDT RESIDUAL LAKE EFFECT ACTIVITY WILL COME TO AN END TUESDAY MORNING WITH DRIER AIR FILTERING FROM UPSTREAM AND ALOFT COMBINING WITH WARMING 850MB TEMPS. RUC13 AND NAM12 ARE FAIRLY SIMILAR IN THIS REGARD WITH QPF AND LOW LEVEL OMEGA FIELDS DECREASING TOWARD 16Z. THEREFORE IMPROVING LAKE CONDITIONS WILL EQUATE TO IMPROVEMENTS FURTHER INLAND. CU RULE CONTINUES TO SUPPORT SCT CONDITIONS (PERHAPS 1-2 HOURS OF BKN) YET THE DRIER AIR ALOFT SEEN IN PROFILES WILL BE SURE TO MIX OUT QUICKLY. BASED ON BUFKIT HOURLY MIXING LAYER HEIGHTS...WE TAP JUST ABOVE 800MB WHICH WOULD EQUATE TO MAX TEMPS INTO THE LOWER HALF OF THE 70S CWA-WIDE (A BIT COOLER NEAR LAKE HURON BUT NOT BY MUCH WITH LAKE TEMPS INTO THE UPPER 60S AND LOWER 70S. AS INDICATED IN THE PREVIOUS AFD...TUESDAY NIGHT AND WEDNESDAY MORNING COULD PROVE TO BE QUITE INTERESTING OVER THE LAKES. SURFACE HIGH SETTLES OVER THE LAKES REGION WITH MOSTLY CLEAR SKIES AND LIGHT WINDS. LOOKS LIKE A GOOD SET UP FOR LAND BREEZE CIRCULATIONS OVERNIGHT AS THE NAM12 AND RUC13 DEPICTS THIS VERY WELL. NAM12 CONTINUES TO ADVERTISE QUITE A CONVERGENCE BAND ACROSS LAKE ERIE LATE TUESDAY NIGHT AND WEDNESDAY MORNING TO IMPACT SOUTHERN MONROE COUNTY TOWARD SUNRISE...AND A MUCH WEAKER ONE OVER SOUTHERN LAKE HURON. THE BEST WATERSPOUT POTENTIAL APPEARS TO BE OVER WESTERN LAKE ERIE ON WEDNESDAY MORNING GIVEN THE CONVECTIVE BAND (PROBABLY JUST TOWERING CU...NOT EVEN SHOWERS). WILL CONTINUE HIGHLIGHT THIS WITHIN THE HWO AT THIS TIME. THEN BIG BUBBLE WITH RIDGE AT ALL LEVELS THROUGH THURSDAY WITH CURRENT TEMPERATURES IN THE GRIDS/FORECAST LOOKING GOOD AND IN CLOSE AGREEMENT WITH THE MEX VALUES. LOOKING FURTHER IN THE EXTENDED...IT BECOMES QUITE COMPLICATED WITH ANOTHER WAVE COMING DOWN ACROSS ALASKA INTO DIGGING TROF ACROSS THE PACIFIC NORTHWEST. THE NAM/GFS AT F84 AGREE WITH THE POTENT WAVE SETTING UP FOR AN ACTIVE DAY ACROSS THE NORTHERN PLAINS WITH THE CANADIAN ABOUT 6-12 HOURS SLOWER. THIS WILL HAVE IMPLICATIONS FOR OUR END OF THE WEEK AND WEEKEND FORECAST WITH A PROLONGED SOUTHWEST FLOW REGIME BEHIND DEPARTING SURFACE HIGH. WITH CONVECTION EMBEDDED WITH THE NUMERICAL SOLUTIONS AND LACK OF UPPER AIR DATA OVER THE NORTH PACIFIC...WE WILL LEAVE THE CHANCE FOR CONVECTION AS IS WITH THE CURRENT FORECAST. BASED ON THIS MORNINGS WATER VAPOR LOOP...THE CANADIAN AND THE DGEX MIGHT HAVE THE RIGHT IDEA WITH TAKING THE LEAD WAVE TO IMPACT THE LAKES ON FRIDAY AND A NARROW RIDGE OF HIGH PRESSURE FOR THE START OF THE WEEKEND (GFS LOOKS TOO AMPLIFIED WITH CONVECTIVE FEEDBACK ISSUES). && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...SMALL CRAFT ADVISORY...LHZ421 UNTIL 6 PM MONDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON-LHZ464 UNTIL MIDNIGHT TUESDAY. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....DG SHORT TERM...DG LONG TERM....BGM HTTP://WEATHER.GOV/DETROIT mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 945 PM CDT MON AUG 22 2005 .DISCUSSION... AREA OF SHRA/TSRA THAT FIRED WITH AFTN HTG HAS ALL BUT DSPTD...WITH ONLY A FEW SPRKLS LINGERING ALG I-70 CORRIDOR OVR MO. AM A BIT UNCERTAIN ABT EXTENT OF REDVLPMT OVRNGT. 00Z NAM IS QUITE ROBUST WITH 2ND ROUND OF PCPN OVR OZARKS IN THE 06-12Z TIME FRAME...BUT WITH SUCH WK FTRS AT LO LVLS I DON'T REALLY SEE THE SIGNALS IN THE MDLS THAT SUPPORT THAT. IF RUC IS CORRECT...SUBTLE INCR IN 85H FLOW WULD SUPPORT ROUND 2...BUT IT WOULD BE A BIT FURTHER S THAN DEPICTED BY NAM. AND WITH MORE STBL AMS GRDLY WORKING SWD OVRNGT...A BIT MORE OF A SWD SHIFT SEEMS REASONABLE. HV OPTED TO KP SM MENTION OF PCPN RMNDR OF TNGT ALG A KCOU-KSTL-KSLO LN. N FRINGES SHUD MNLY BE LIMITED TO SPRINKLES...WITH CHC POPS FOR SHRA/TSRA CONTG ALG-S OF KJEF-KSAR LN. NO OTHER CHGS RQRD. && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE IL...NONE. && $$ TRUETT mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 254 PM CDT MON AUG 22 2005 .DISCUSSION... SCATTERED STORMS CONTINUE TO POP UP ACROSS EAST CENTRAL KANSAS AND WEST CENTRAL MISSOURI THANKS TO THE HELP OF AN UPPER LEVEL DISTURBANCE AND A WEAK STATIONARY SURFACE BOUNDARY. SURFACE OBSERVATIONS PLACE THE BOUNDARY AROUND OR JUST SOUTH OF INTERSTATE 70 EARLY THIS AFTERNOON...WITH OVERCAST SKIES TO THE SOUTH OF IT...AND PARTLY SUNNY SKIES TO THE NORTH. COOL DRY AIR CAN ALSO BEEN SEEN WORKING ITS WAY WEST AND SOUTH UNDER THE DOME OF SURFACE HIGH PRESSURE CENTERED OVER NORTHERN MINNESOTA. SO..DESPITE THE SUNSHINE IN NORTHERN MISSOURI TODAY...TEMPERATURES HAVE BEEN SLOW TO CLIMB OUT OF THE 70S. CONVECTION FOR THE REMAINDER OF THE AFTERNOON SHOULD REMAIN SCATTERED IN NATURE. A WEAK SHEAR AXIS ALOFT IS NOW EVIDENT IN RADAR LOOPS ALONG THE APPROXIMATE LOCATION OF THE SURFACE BOUNDARY IN WEST CENTRAL MISSOURI. THE WEAK WINDS ALOFT...EVEN WITHIN THE SHEAR AXIS...ARE CONTRIBUTING TO A LACK OF STORM MOVEMENT. WITH THE DISTURBANCE ALOFT SLOWLY DRIFTING EAST OVERNIGHT...I HAVE LEFT OUR CHANCE THUNDER POPS ALONE FOR ANY LINGERING ACTIVITY. THOUGH...I HAVE REORIENTED THEM A LITTLE MORE EAST WEST ALONG AND SOUTH OF THE MISSOURI RIVER. FOR TUESDAY...MORE OF THE SAME WEATHER IS EXPECTED. YET ANOTHER WEAK UPPER LEVEL DISTURBANCE WILL EJECT ACROSS THE MOISTURE PLUM STRETCHING ACROSS THE CENTRAL PLAINS...REINFORCING OUR POTENTIAL FOR STORMY ACTIVITY ALONG AND SOUTH OF THE BOUNDARY THAT IS LANGUISHING ACROSS CENTRAL MISSOURI. WITH THE CLOUD COVER ACROSS THE SOUTHWEST HALF OF THE FORECAST AREA...AND THE COOL DRIER AIR MASS ACROSS THE NORTHEAST HALF...I HAVE BUMPED TEMPERATURES DOWN A DEGREE OR THREE. WEDNESDAY LOOKS TO REMAIN DRY. THE RIDGE MOVING THROUGH THE NORTH CENTRAL PLAINS SHOULD HELP PUSH MORE DRY AIR INTO MISSOURI FROM THE NORTHEAST. EXPECTATIONS ARE THAT THIS WILL KEEP ANY POP UP CONVECTION FARTHER WEST ALONG WITH THE MOISTURE AXIS. WITHOUT THE THICKER CLOUD COVER FROM CONVECTION...THE SOUTHERLY COMPONENT CREEPING INTO THE WIND FIELD SHOULD HELP OUR TEMPERATURES REBOUND A LITTLE. THEREFORE I HAVE CONTINUED TO GO WITH TEMPERATURES A COUPLE OF DEGREES ABOVE GUIDANCE FOR WEDNESDAY AFTERNOON. CUTTER AS DEEP TROUGH OVER THE NORTHEASTERN U.S. PUSHES FURTHER EAST EXPECT UPPER RIDGE TO BOUNCE BACK AND BULGE NORTHEAST INTO THE GREAT LAKES BY MID WEEK. THIS SHOULD ALLOW A RETURN OF SOUTHERLY BOUNDARY LAYER WINDS. THIS WILL MAINTAIN THE SURFACE DEWPOINTS IN THE UPPER 60S. NAM/GFS/CANADIAN MODELS HAVE SIMILAR SOLUTION BY MID WEEK. THESE MODELS CONTINUE THE RECENT TREND OF TRACKING UPPER VORTICITY CENTERS NORTHEAST OUT OF CO/NM. AT THE SAME TIME A STRONG UPPER TROUGH WILL BE MARCHING EAST ACROSS THE NORTHERN ROCKIES AND NORTHERN PLAINS. SOUTHWEST FLOW ALOFT WILL ENABLE ANY SHORTWAVE/VORTICITY CENTER TO TRACK NORTHEAST FROM THE SOUTHERN ROCKIES AND INTO THE CENTRAL PLAINS. NAM/GFS/CANADIAN GENERATE AN AREA OF CONVECTION AHEAD OF THESE UPPER FEATURES AND TRACK IT ACROSS KS AND INTO WESTERN MO WEDNESDAY NIGHT AND THURSDAY. HAVE BUMPED POPS INTO CHANCE CATEGORY FOR THURSDAY DUE TO MODEL SIMILARITIES. COLD FRONT ASSOCIATED WITH NORTHERN UPPER SYSTEM EXPECTED TO AFFECT CWA BY LATE THURSDAY NIGHT. MEDIUM RANGE MODELS SIMILAR IN PLACEMENT OF UPPER TROUGH AXIS BY 00Z FRIDAY WITH TROUGH AXIS ROUGHLY NEAR THE WESTERN DAKOTAS BORDER. NAM/GFS A BIT DEEPER WITH UPPER SYSTEM WHILE MODELS IN GENERAL ARE FAIRLY PROGRESSIVE NOW. BY 00Z SATURDAY UPPER SUPPORT/FORCING WILL HAVE SHIFTED INTO THE GREAT LAKES SO COLD FRONT SHOULD STALL AS IT MOVES INTO THE CENTRAL PLAINS AND MID MO VALLEY. TAKING INTO CONSIDERATION A SLOWER FRONTAL MOVEMENT SPREAD CHANCE POPS ACROSS ENTIRE REGION ON FRIDAY. AIRMASS AHEAD OF FRONT SHOULD BECOME MODERATELY UNSTABLE SO IF COLD FRONT CAN LINGER OVER CWA ON FRIDAY THERE COULD BE A RISK OF SEVERE WEATHER. HAVE GONE CONSERVATIVE ON MAX TEMPERATURES OVER THE WEEKEND DUE TO UNCERTAINTY OF FRONTAL POSITION. BUT MODELS HINT THAT FRONT COULD RETURN NORTH FAIRLY QUICK OR NOT MOVE THROUGH CWA AT ALL...THUS LATER FORECASTS MAY NEED TO RAISE TEMPERATURES OVER THE WEEKEND BY A CATEGORY OR TWO. JULY && .PREVIOUS DISCUSSION... 1123 AM... QUICK ADJUSTMENT TO THE FORECAST THIS MORNING FOR EVOLVING STORM ACTIVITY. SCATTERED STORM HAVE POPPED UP ALONG AND NORTH OF THE WEAKLY DEFINED STATIONARY SURFACE FRONT ACROSS THE FAR SOUTHERN EDGE OF THE FORECAST AREA. NO WELL DEFINED WAVE OR MCV CAN BE CAN BE SEEN ON SATELLITE IMAGERY...BUT A WEAK LOW LEVEL JET IS NOTED MOVING ACROSS THE TOP OF A SMALL SURFACE HIGH LEFT OVER FROM FROM OVERNIGHT CONVECTION IN NORTHEAST OKLAHOMA AND SOUTHEAST KANSAS. THOUGHTS ARE THIS JET IS PROVIDING ENOUGH CONVERGENCE ALONG THE NORTHERN EDGE OF THE HIGH TO SPARK THE SHOWERS AND T-STORMS THAT ARE CURRENTLY SPREADING ACROSS EAST CENTRAL KANSAS AND WEST CENTRAL MISSOURI. MODELS AND DIURNAL TRENDS TRENDS WOULD INDICATE THAT THE JET SHOULD CONTINUE TO VEER AS WE MOVE INTO THE AFTERNOON HOURS...OR BREAK DOWN ALL TOGETHER. THEREFORE...ONLY BUMPED POPS INTO THE LIKELY RANGE FOR THE ACTIVITY GOING ON THE FAR SOUTHWESTERN PORTION OF THE CWA THROUGH THE EARLY AFTERNOON HOURS. WENT WITH HIGH CHANCE POPS FOR THE REMAINDER OF THE AFTERNOON HOURS ACROSS THE SOUTHWEST HALF OF THE FORECAST AREA. GOING TEMPERATURE TRENDS STILL LOOK GOOD. CUTTER 345 PM... WATER VAPOR IMAGERY CONTINUES TO DEPICT AN UNSEASONABLY COMPLEX SPLIT FLOW REGIME EVOLVING ACROSS THE CONUS EARLY THIS MORNING. LATEST UPPER AIR ANALYSIS SHOWS THAT THE NORTHERN TWO-THIRDS OF MISSOURI HAVE BEEN LEFT IN A COL BETWEEN A DEPARTING STORM SYSTEM OVER ONTARIO...AND SOUTHERN STREAM WESTERLIES OVER SRN MO/AR/OK. AT THE SURFACE...BACKDOOR FRONT DENOTED BY NORTHERLY WIND SHIFT AND SHARP DEWPOINT GRADIENT HAS FINALLY PUSHED ACROSS THE IA/MO BORDER. FORECAST CHALLENGES FOR THE NEXT SEVERAL DAYS WILL HINGE UPON VERY SLOW PROGRESSION OF UPPER LEVEL FEATURES AND THE SOUTHWARD MOMENTUM OF THE BACKDOOR FRONT INTO THE CWA. REGARDING THE LATTER CONCERN...SHORT TERM MODEL SOLUTIONS ARE CONSISTENT WITH BUILDING A SHORTWAVE RIDGE ACROSS THE UPPER MIDWEST OVER THE NEXT 24 HOURS. HEIGHT RISES AND LARGE SCALE SUBSIDENCE WILL ALLOW THE ATTENDANT SURFACE HIGH TO BROADEN OVER THE WESTERN LAKES REGION...AND RE-ENERGIZE THE SOUTHWARD PROGRESSION OF THE BACKDOOR FRONT. THIS WILL ALLOW A MUCH DRIER LOW LEVEL AIRMASS...WITH DEWPOINTS IN THE UPPER 50S TO LOWER 60S...TO PENETRATE AT LEAST THE NORTHEAST HALF OF THE CWA. MEANWHILE...AMPLE MID-UPPER LEVEL MOISTURE TRAPPED WITHIN WEAK UPPER FLOW REGIME WILL PERSIST OVER THE REGION THROUGH THE NEXT SEVERAL DAYS. SEVERAL EMBEDDED SHORTWAVES TRANSLATING ACROSS THE SOUTHERN PLAINS WILL BRING ADDITIONAL PACIFIC MOISTURE INTO THE REGION...WITH CONTINUED BROKEN/OVERCAST PERIODS RESULTING IN PLEASANTLY COOL TEMPERATURES WITH HIGHS GENERALLY IN THE UPPER 70S NORTH TO MID 80S SOUTH. CLOUD COVER WILL ALSO LIMIT THE DEGREE OF INSTABILITY OVER THE REGION...HOWEVER THE THREAT OF RAINFALL IS CERTAINLY NOT ZERO. ISOLATED SHOWERS/STORMS CONTINUE TO DEVELOP WITHIN A NARROW MID LEVEL MOIST AXIS OVER SRN IA EARLY THIS MORNING. RUC ANALYSIS SHOWS THIS ACTIVITY DEVELOPING WITHIN A NARROW MID LEVEL MOISTURE AXIS WHICH IS PROGGED TO SHIFT SOUTH AHEAD OF ELEVATED FRONTAL ZONE THIS MORNING. A FEW SHOWERS OR STORMS COULD AFFECT AREAS ALONG AND NORTH OF A BETHANY TO KIRKSVILLE LINE THIS MORNING...BUT A GRADUAL DISSIPATING TREND IS EXPECTED. ELSEWHERE...ISOLATED/SCATTERED AFTERNOON CONVECTION COULD ALSO DEVELOP SOUTH OF I-70 WHERE MOIST AIRMASS AHEAD OF BACKDOOR FRONT MAY BE REALIZED AS A VIGOROUS SHORTWAVE OVER OKLAHOMA TRACKS ACROSS SRN MO. OTHERWISE...A BETTER CHANCE FOR SHOWERS/STORMS IS EXPECTED OVER ERN KS/WRN MO TONIGHT AND TUESDAY AS A PAIR OF UPPER LEVEL CIRCULATIONS OVER CENTRAL KANSAS AND EASTERN COLORADO MEANDER EASTWARD. MODEST DOWNSTREAM WARM ADVECTION REGIME...COMBINED WITH LOW-MID LEVEL BAROCLINIC AXIS AND MOISTURE GRADIENT ALREADY IN PLACE...SHOULD PROVIDE ENOUGH SUPPORT FOR AT LEAST SCATTERED SHOWERS/STORMS. BULLISH QPF ADVERTISED BY THE NAM AND TO A LESSER EXTENT THE GFS SEEMS TO BE A BIT OVERDONE GIVEN LACK OF PROGGED INSTABILITY. NEVERTHELESS...SOME AREAS COULD CERTAINLY STAND TO SEE A TENTH TO QUARTER INCH OF RAINFALL. LOOKING AHEAD...SYNOPTIC TREND CONTINUES TO KEEP UPPER LEVEL RIDGE UNSEASONABLY FAR SOUTH...ALLOWING FOR STRONG WESTERLIES TO PERSIST ACROSS THE NRN HALF OF THE US. ANOTHER POTENT PACIFIC STORM SYSTEM IS PROGGED TO TRANSLATE ACROSS THE NORTHERN TIER STATES MID WEEK...AND MAY NECESSITATE RAIN CHANCES MID-LATE WEEK. BOOKBINDER && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE MO...NONE $$ WFO EAX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 1210 PM CDT MON AUG 22 2005 ...MESOSCALE CONVECTIVE DISCUSSION... WILL BE CLOSELY MONITORING AREAS OF CENTRAL AND WEST CENTRAL MISSOURI FOR ISOLATED STRONG THUNDERSTORMS THIS AFTERNOON. DEEP MOISTURE CONVERGENCE ASSOCIATED WITH A STALLED OUT COLD FRONT POSITIONED ALONG A LINE FROM FORT SCOTT KANSAS TO EMINENCE MISSOURI WILL AID IN AFTERNOON CONVECTION. DESPITE THE CLOUD COVER...THIS AREA HAS SOMEWHAT DESTABILIZED WITH LAPS 100 ML CAPES NOW APPROACHING 1500 J/KG EARLY THIS AFTERNOON. THIS AREA IS ALSO EXPERIENCING WEAK LIFT FROM BEING POSITIONED UNDER THE RIGHT ENTRANCE REGION OF A 200 MB SPEED MAX. RUC AND MESO ETA POINT FORECAST SOUNDINGS OVER WEST CENTRAL MISSOURI SHOW HIGH FREEZING AND WET BULB ZERO LEVELS...THEREFORE HAIL POTENTIAL IS LIMITED. STRONG WIND GUSTS AND MINOR FLOODING WOULD BE THE PRIMARY HAZARDS. .DISCUSSION... A COMPLEX WEATHER SCENARIO HAS SET UP ACROSS THE EASTERN PLAINS AND MISSOURI OZARK REGION TODAY. SEVERAL MINOR LIFTING MECHANISMS COULD POTENTIALLY DEVELOP SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON. THUNDERSTORMS HAVE ALREADY DEVELOPED OVER EAST CENTRAL KANSAS AND WEST CENTRAL MISSOURI...WHERE SURFACE CONVERGENCE IS OCCURRING ALONG A COLD FRONT STALLED OUT ACROSS THIS AREA. ALSO...UPPER AIR ANALYSIS INDICATED A 200 MB SPEED MAX OVER MUCH OF THE CORN BELT...WITH EAST CENTRAL KANSAS/WEST CENTRAL MISSOURI UNDER THE RIGHT ENTRANCE REGION OF THE SPEED MAX. RUC ANALYSIS SUPPORTS WEAK UPPER LIFT...SUGGESTING A DIVERGENCE BULLSEYE IN THE AREA WHERE THUNDERSTORMS HAVE DEVELOPED. ALSO TO NOTE...700MB RAOB ANALYSIS INDICATED A MINOR SHORTWAVE ACROSS CENTRAL KANSAS THAT COULD BE AIDING IN LIFT. WITH PRECIPITABLE WATER VALUES ON THE ORDER OF 1.80...ANY MINOR SOURCE OF LIFT WILL LIKELY DEVELOP A SHOWER TODAY...THEREFORE...WENT AHEAD AND RECONFIGURED THIS AFTERNOONS POPS TO WEIGHT HIGHEST POPS OVER WEST CENTRAL MISSOURI AND SE KANSAS. LEFT CHANCE POPS IN FOR THE REST OF THE CWA. TWEAKED TEMPERATURES DOWN A COUPLE DEGREES GIVEN THE CLOUD COVER AND PRECIP. SAT TRENDS SUGGEST THAT THE ENTIRE CWA SHOULD CONTINUE TO OBSERVED CONSIDERABLE CLOUDS THROUGH THE AFTERNOON LIMITING TEMPERATURES IN THE LOW TO MID 80S. && .AVIATION... THE COMBINATION OF A COLD FRONT AND A WEAK UPPER LEVEL DISTURBANCE WILL CAUSE SCATTERED SHOWERS AND THUNDERSTORMS TO CONTINUE ACROSS MUCH OF EXTREME SOUTHEAST KANSAS AND THE MISSOURI OZARKS THIS AFTERNOON AND EVENING. IF JOPLIN OR SPRINGFIELD AIRPORTS ARE DIRECTLY IMPACTED BY A STORM...THEN FLIGHT CONDITIONS COULD FALL WITHIN THE IFR CATEGORY. ALL TWEB ROUTES WILL BE AFFECTED BY SHOWERS AND THUNDERSTORMS AS WELL. LOOK FOR CEILINGS TO FALL INTO THE MVFR TO IFR RANGE AS THE FRONT SHIFTS SOUTH INTO SOUTHERN MISSOURI. && SGF WATCHES/WARNINGS/ADVISORIES... .MO...NONE. .KS...NONE. $$ CRAMER mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 1123 AM CDT MON AUG 22 2005 .DISCUSSION... QUICK ADJUSTMENT TO THE FORECAST THIS MORNING FOR EVOLVING STORM ACTIVITY. SCATTERED STORM HAVE POPPED UP ALONG AND NORTH OF THE WEAKLY DEFINED STATIONARY SURFACE FRONT ACROSS THE FAR SOUTHERN EDGE OF THE FORECAST AREA. NO WELL DEFINED WAVE OR MCV CAN BE CAN BE SEEN ON SATELLITE IMAGERY...BUT A WEAK LOW LEVEL JET IS NOTED MOVING ACROSS THE TOP OF A SMALL SURFACE HIGH LEFT OVER FROM FROM OVERNIGHT CONVECTION IN NORTHEAST OKLAHOMA AND SOUTHEAST KANSAS. THOUGHTS ARE THIS JET IS PROVIDING ENOUGH CONVERGENCE ALONG THE NORTHERN EDGE OF THE HIGH TO SPARK THE SHOWERS AND T-STORMS THAT ARE CURRENTLY SPREADING ACROSS EAST CENTRAL KANSAS AND WEST CENTRAL MISSOURI. MODELS AND DIURNAL TRENDS TRENDS WOULD INDICATE THAT THE JET SHOULD CONTINUE TO VEER AS WE MOVE INTO THE AFTERNOON HOURS...OR BREAK DOWN ALL TOGETHER. THEREFORE...ONLY BUMPED POPS INTO THE LIKELY RANGE FOR THE ACTIVITY GOING ON THE FAR SOUTHWESTERN PORTION OF THE CWA THROUGH THE EARLY AFTERNOON HOURS. WENT WITH HIGH CHANCE POPS FOR THE REMAINDER OF THE AFTERNOON HOURS ACROSS THE SOUTHWEST HALF OF THE FORECAST AREA. GOING TEMPERATURE TRENDS STILL LOOK GOOD. CUTTER && .PREVIOUS DISCUSSION... 345 PM... WATER VAPOR IMAGERY CONTINUES TO DEPICT AN UNSEASONABLY COMPLEX SPLIT FLOW REGIME EVOLVING ACROSS THE CONUS EARLY THIS MORNING. LATEST UPPER AIR ANALYSIS SHOWS THAT THE NORTHERN TWO-THIRDS OF MISSOURI HAVE BEEN LEFT IN A COL BETWEEN A DEPARTING STORM SYSTEM OVER ONTARIO...AND SOUTHERN STREAM WESTERLIES OVER SRN MO/AR/OK. AT THE SURFACE...BACKDOOR FRONT DENOTED BY NEARLY WIND SHIFT AND SHARP DEWPOINT GRADIENT HAS FINALLY PUSHED ACROSS THE IA/MO BORDER. FORECAST CHALLENGES FOR THE NEXT SEVERAL DAYS WILL HINGE UPON VERY SLOW PROGRESSION OF UPPER LEVEL FEATURES AND THE SOUTHWARD MOMENTUM OF THE BACKDOOR FRONT INTO THE CWA. REGARDING THE LATTER CONCERN...SHORT TERM MODEL SOLUTIONS ARE CONSISTENT WITH BUILDING A SHORTWAVE RIDGE ACROSS THE UPPER MIDWEST OVER THE NEXT 24 HOURS. HEIGHT RISES AND LARGE SCALE SUBSIDENCE WILL ALLOW THE ATTENDANT SURFACE HIGH TO BROADEN OVER THE WESTERN LAKES REGION...AND RE-ENERGIZE THE SOUTHWARD PROGRESSION OF THE BACKDOOR FRONT. THIS WILL ALLOW A MUCH DRIER LOW LEVEL AIRMASS...WITH DEWPOINTS IN THE UPPER 50S TO LOWER 60S...TO PENETRATE AT LEAST THE NORTHEAST HALF OF THE CWA. MEANWHILE...AMPLE MID-UPPER LEVEL MOISTURE TRAPPED WITHIN WEAK UPPER FLOW REGIME WILL PERSIST OVER THE REGION THROUGH THE NEXT SEVERAL DAYS. SEVERAL EMBEDDED SHORTWAVES TRANSLATING ACROSS THE SOUTHERN PLAINS WILL BRING ADDITIONAL PACIFIC MOISTURE INTO THE REGION...WITH CONTINUED BROKEN/OVERCAST PERIODS RESULTING IN PLEASANTLY COOL TEMPERATURES WITH HIGHS GENERALLY IN THE UPPER 70S NORTH TO MID 80S SOUTH. CLOUD COVER WILL ALSO LIMIT THE DEGREE OF INSTABILITY OVER THE REGION...HOWEVER THE THREAT OF RAINFALL IS CERTAINLY NOT ZERO. ISOLATED SHOWERS/STORMS CONTINUE TO DEVELOP WITHIN A NARROW MID LEVEL MOIST AXIS OVER SRN IA EARLY THIS MORNING. RUC ANALYSIS SHOWS THIS ACTIVITY DEVELOPING WITHIN A NARROW MID LEVEL MOISTURE AXIS WHICH IS PROGGED TO SHIFT SOUTH AHEAD OF ELEVATED FRONTAL ZONE THIS MORNING. A FEW SHOWERS OR STORMS COULD AFFECT AREAS ALONG AND NORTH OF A BETHANY TO KIRKSVILLE LINE THIS MORNING...BUT A GRADUAL DISSIPATING TREND IS EXPECTED. ELSEWHERE...ISOLATED/SCATTERED AFTERNOON CONVECTION COULD ALSO DEVELOP SOUTH OF I-70 WHERE MOIST AIRMASS AHEAD OF BACKDOOR FRONT MAY BE REALIZED AS A VIGOROUS SHORTWAVE OVER OKLAHOMA TRACKS ACROSS SRN MO. OTHERWISE...A BETTER CHANCE FOR SHOWERS/STORMS IS EXPECTED OVER ERN KS/WRN MO TONIGHT AND TUESDAY AS A PAIR OF UPPER LEVEL CIRCULATIONS OVER CENTRAL KANSAS AND EASTERN COLORADO MEANDER EASTWARD. MODEST DOWNSTREAM WARM ADVECTION REGIME...COMBINED WITH LOW-MID LEVEL BAROCLINIC AXIS AND MOISTURE GRADIENT ALREADY IN PLACE...SHOULD PROVIDE ENOUGH SUPPORT FOR AT LEAST SCATTERED SHOWERS/STORMS. BULLISH QPF ADVERTISED BY THE NAM AND TO A LESSER EXTENT THE GFS SEEMS TO BE A BIT OVERDONE GIVEN LACK OF PROGGED INSTABILITY. NEVERTHELESS...SOME AREAS COULD CERTAINLY STAND TO SEE A TENTH TO QUARTER INCH OF RAINFALL. LOOKING AHEAD...SYNOPTIC TREND CONTINUES TO KEEP UPPER LEVEL RIDGE UNSEASONABLY FAR SOUTH...ALLOWING FOR STRONG WESTERLIES TO PERSIST ACROSS THE NRN HALF OF THE US. ANOTHER POTENT PACIFIC STORM SYSTEM IS PROGGED TO TRANSLATE ACROSS THE NORTHERN TIER STATES MID WEEK...AND MAY NECESSITATE RAIN CHANCES MID-LATE WEEK. BOOKBINDER && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE MO...NONE $$ WFO EAX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTH PLATTE NE 1136 AM CDT MON AUG 22 2005 .DISCUSSION... FORECAST UPDATED TO COOL MAX TEMPS AND ADJUST WX GRIDS AS MOST ACTIVITY THROUGH TODAY LOOKS TO BE IN THE EASTERN AND SOUTHERN CWA. STRATUS HANGING IN WITH SHARP GRADIENT FROM WEST TO EAST. THIS PUTS KVTN TAF RIGHT ON THE EDGE. LACK OF LOW CLOUD COVER OVER THE SW ZONES REFLECTED IN HIGHER INSTABILITY WITH BETTER CHANCES FOR THUNDER THIS AFTERNOON. .PREV DISCUSSION... ...FORECAST CONCERNS WILL CENTER AROUND POPS NEXT FEW DAYS... HIGH PRESSURE ACROSS THE UPPER MIDWEST IS FCST BY THE NAM TO BUILD EWD ACTING TO FUNNEL MOISTURE WESTWARD THRU 84 HR. THE NAM AND IN PARTICULAR THE FWC/MET/MAV GUIDANCE ALL SUGGEST GENERALLY CLOUDY CONDITIONS WITH MAX TEMPERATURES AROUND 80F AS SUBTROPICAL MOISTURE WRAPS OVER THE SFC RIDGE. GUIDANCE ALSO SUGGESTS AM STRATUS THROUGH THIS PERIOD AND SOME CHC POPS EACH DAY. FOR TODAY AND TONIGHT...APPEARS THE SYNOPTIC CONDITIONS OVER KS THE PREVIOUS DAY WILL TRANSLATE NWD IN RESPONSE TO THE COLORADO SHORT WAVE MOVING AROUND THE PERIPHERY OF SUBTROPICAL RIDGE. NAM MODEL SNDGS SUGGESTS MORE MOIST PROFILES BUT LESS INSTABILITY. EXPECT MORE SHRA/TSRA TO DEVELOP THIS AFTN AS THE COLO S.W. CONTINUES TO GLIDE SLOWLY EWD. MID TO HIGH CLOUDS SHOULD HOLD TEMPS MOSTLY 77 TO 87F. NO LOW LEVEL STATUS HAS DEVELOPED YET AS FCST BY THE RUC/NAM SO TEMPS TODAY WILL BE NUDGED 1 CATEGORY ABOVE CONSENSUS GUIDANCE WHICH FACTORS IN THE STRATUS. TUESDAY...NRN PLAINS LOW PRESSURE WILL DRAW HIGH THETA E AIR N AND WWD ACROSS THE HIGH PLAINS OF NEBRASKA. LAPSE RATES PER K INDEX IN THE 40S SHOULD BE SUFFICIENT FOR LATE AFTN/EVENING CONVECTION WITH ACTIVITY SPREADING EAST OVERNIGHT. INCREASING 0-6KM SHEAR ASSOCIATED WITH NRN STREAM MID LEVEL WAVE APPEARS FAVORABLE FOR A FEW SEVERE STORMS. WEDNESDAY...PRESUMABLY...A COLD FRONT APPROACHES FCST AREA LATE IN THE AFTERNOON/EVENING AS AN UPPER LEVEL LOW SWINGS THROUGH SRN CANADA. WINDS ALOFT...THETA E RIDGE ON THE HIGH PLAINS...K INDICES NEAR 40 AND UPPER LEVEL FORCING SUGGEST ANOTHER DECENT CHANCE OF TSRA AND A FEW COULD BE SEVERE. THURSDAY/FRIDAY...BOTH THE NAM AND THE GFS APPEAR TO SLOW THE COLD FRONT UP OVER NEBRASKA. THIS IS VERY SIMILAR TO RECENT WEATHER PATTERNS OF AUGUST AND POSSIBLY IN RESPONSE TO THE RICH AUGUST MOISTURE FIELD OVER THE SRN PLAINS. NO REAL CHANGE HAS BEEN MADE TO THE FCST...CONTINUE SLGHT CHC POPS AND NAM/GFS SUGGEST DIURNAL CONVECTION. SATURDAY/SUNDAY...FCST AT THIS POINT IS DRY. THE LATEST RUN KEEPS CHC POPS THRU SAT/SUN BUT RUN TO RUN CONTINUITY HAS BEEN POOR THIS FAR OUT SO WILL LEAVE THE FCST ALONE. BOTH MODELS DO SUGGEST THE SUBTROPICAL RIDGE WILL MIGRATE NWD ONCE AGAIN AND DISTURBANCE WILL MOVE AROUND THE PERIPHERY OF THE RIDGE. && LBF WATCHES/WARNINGS/ADVISORIES...NONE. && $$ CDC/JMC ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 1150 AM CDT MON AUG 22 2005 .DISCUSSION... UPDATE NUMBER TWO FOR EXPANDING CUMULUS FIELD. HAD TO ADD EVEN MORE CLOUDS TO THE AFTERNOON CLOUD GRIDS. PREVIOUS UPDATE... MINOR UPDATE PLANNED THIS MORNING FOR A BIT MORE CLOUD COVER IN THE SOUTHEAST FA. HIGH PRESSURE IN CONTROL WITH LOTS OF SUN EXPECTED ELSEWHERE. RUC CU RULES SHOW SOME SCATTERED TO BROKEN CLOUDS LIKELY TO HANG ON IN THE SOUTHEAST FA INTO THE AFTERNOON. NO CHANGES TO THE OTHER FORECAST ELEMENTS. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ GODON nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 1000 AM CDT MON AUG 22 2005 .DISCUSSION... MINOR UPDATE PLANNED THIS MORNING FOR A BIT MORE CLOUD COVER IN THE SOUTHEAST FA. HIGH PRESSURE IN CONTROL WITH LOTS OF SUN EXPECTED ELSEWHERE. RUC CU RULES SHOW SOME SCATTERED TO BROKEN CLOUDS LIKELY TO HANG ON IN THE SOUTHEAST FA INTO THE AFTERNOON. NO CHANGES TO THE OTHER FORECAST ELEMENTS. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ GODON nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 911 PM EDT MON AUG 22 2005 .SHORT TERM (REST OF TONIGHT)... TROUGH OF LOW PRESSURE WILL CONTINUE OVER THE AREA FOR THE REMAINDER OF THE NIGHT. RUC MODEL HAS A 925 MB LOW PRESSURE IN NORTH GEORGIA THAT WILL REMAIN TONIGHT AND BRING A MOIST SOUTHEAST WINDFLOW OVER THE AREA. RUC IS ALSO BRINGING NVA OVER AREA BUT IR SATELLITE IMAGERY IS SHOWING SOME COOLING TOPS IN THE NORTHWEST PART OF SOUTH CAROLINA. SO THERE COULD BE A FEW THUNDERSTORMS IN ADDITION TO THE SHOWERS OVERNIGHT. PLAN ON KEEPING THE 50 PERCENT CHANCE OF SHOWERS AND THUNDERSTORMS. OTHERWISE...LOW TEMPERATURES AND WINDS STILL LOOK OK. SO WILL ISSUE UPDATE DROPPING THE REFERENCES TO 70 PERCENT CHANCE FOR THE REST OF THE AFTERNOON PERIOD. && .PREVIOUS DISCUSSION... (ISSUED 146 PM EDT MON AUG 22 2005) SHORT TERM (TONIGHT THROUGH WEDNESDAY)... THE DIFFUSE FRONT EXTENDING THROUGH THE FORECAST AREA PLUS STRONG HEATING HAS HELPED CAUSE SCATTERED THUNDERSTORMS THIS AFTERNOON. EXPECT COVERAGE WILL CONTINUE TO INCREASE AS THE MID-LEVEL SHORTWAVE TROUGH SHOWN ON THE WATER VAPOR IMAGERY MOVING INTO WESTERN GEORGIA APPROACHES THE FORECAST AREA. THE HIGHER MAV POPS APPEAR BETTER TONIGHT...MAINLY FOR THIS EVENING BECAUSE OF THIS FEATURE. INSTABILITY HAS BECOME MODERATE WITH LI/S NEAR -7 IN THE SOUTH PART SO SEVERE WIND GUSTS MAY OCCUR WITH SOME OF THE STORMS. THERE SHOULD BE LESS OF A SEVERE HAIL THREAT BECAUSE OF RELATIVELY WARM MID-LEVEL TEMPERATURES. THE LATEST SPC MESO ANALYSIS SHOWS H5 TEMPERATURES NEAR -5. SLOW MOVEMENT AND HIGH PRECIPITABLE WATER ALSO SUPPORTS VERY HEAVY RAIN WITH SOME OF THE THUNDERSTORMS. BELIEVE THE DIFFUSE FRONT WILL REMAIN IN THE FORECAST AREA WITH A SERIES OF MID-LEVEL SHORT WAVE TROUGHS THROUGH WEDNESDAY. MOST OF THE GUIDANCE IS IN CLOSE AGREEMENT WITH THE MAV POPS AND PLAN TO FOLLOW. LONG TERM (WEDNESDAY NIGHT THROUGH MONDAY)... THE THUNDERSTORM CHANCE APPEARS LOW DURING THE EXTENDED PERIOD. THE GFS SHOWS SURFACE RIDGING DOMINATING THURSDAY AND FRIDAY. AN ONSHORE FLOW SHOULD CAUSE AN INCREASE IN LOW-LEVEL MOISTURE SATURDAY THROUGH MONDAY. H5 RIDGING SHOULD LIMIT INSTABILITY THROUGH THE PERIOD. PLAN TO KEEP SLIGHT CHANCE OF MAINLY AFTERNOON AND EVENING THUNDERSTORMS. AVIATION... && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$ 07 sc AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 1007 AM CDT MON AUG 22 2005 .DISCUSSION NO BIG CHGS IN FIRST PD OF PREV FCST ATTM. CWA TO STAY IN ESE FLOW BETWEEN GTLKS HIGH AND NRN RCKYS LOW THRU TONIGHT. SRN THIRD OF CWA WL SEE MORE MID AND HI CLDS THRU THIS AFTN...SO HAVE CUT BACK FIRST PD TEMPS A COUPLE DEGREES THERE. HAVE ALSO CUT BACK TEMPS A COUPLE DEGREES IN NERN ZONES DUE TO ERLY WINDS WHICH GENERALLY LEAD TO VERY LTL MIXING AND SLIGHT UPSLOPE INTO BUFFALO RIDGE. 12Z ETA12 AND RUC ALSO SUPPORT SLIGHTLY COOLER TEMPS IN FAR S AND FAR NE FOR THIS AFTN. && .PREVIOUS DISCUSSION... FAIRLY QUIET FORECAST IN THE NEAR TERM...WITH THE WEATHER PATTERN BECOMING MORE ACTIVE MIDWEEK AS A SERIES OF WEAK SHORT WAVES PASS OVER THE AREA AHEAD OF A LOW PRESSURE SYSTEM WHICH WILL AFFECT THE AREA LATE IN THE WEEK. CURRENT SURFACE ANALYSIS SHOWS WEAK SURFACE BOUNDARY CONTINUING TO INCH SOUTH ACROSS UPPER MIDWEST. AS OF 08Z THIS MORNING...THE BOUNDARY WAS LOCATED FROM JUST SOUTH OF KIRKSVILLE MO...THROUGH FALLS CITY NE AND CHADRON NE. MID AND HIGH LEVEL CLOUDS ASSOCIATED WITH RAPIDLY WEAKENING CONVECTION TO THE SOUTH WILL CONTINUE TO ADVECT INTO SOUTH WEST AND SOUTH CENTRAL PORTIONS OF CWA THROUGH MUCH OF THE DAY AND HAVE THEREFORE TWEAKED HIGH TEMPERATURES TODAY DOWN SLIGHTLY ALONG SOUTHERN EDGE. EXPECT ATMOSPHERE IN THE VICINITY OF THE FRONT TO DESTABILIZE ONCE AGAIN TODAY AND CREATE ADDITIONAL SHOWERS AND THUNDERSTORMS. DO NOT EXPECT THESE SHOWERS AND THUNDERSTORMS TO AFFECT THE CWA DIRECTLY THIS EVENING...BUT INSTEAD JUST AFFECT AREAS FROM KYKN TO KSUX WITH ADDITIONAL CLOUD COVER. OTHERWISE...THE REST OF THE FORECAST AREA SHOULD REMAIN MOSTLY CLEAR. NEXT WEATHER DISTURBANCE OF SIGNIFICANCE WILL APPROACH FROM THE WEST ON TUESDAY. ATMOSPHERE TO REMAIN FAIRLY DRY AHEAD OF THE SHORT WAVE...SO THINKING ANY PRECIPITATION THAT IS ABLE TO DEVELOP WILL HAVE A HARD TIME REACHING THE SURFACE. HAVE THEREFORE REMOVED CHANCE OF POPS IN THE EVENING HOURS...BUT KEPT POPS IN THE OVERNIGHT HOURS AS MOISTURE WILL BEGIN TO INCREASE ACROSS THE REGION WITH THE AID OF A 20-30 KT LOW LEVEL JET ADVECTING MOISTURE NORTHWARD FROM THE GULF. WEAK WAVES CONTINUE TO TRAVERSE THE CWA THROUGHOUT THE DAY ON WEDNESDAY AND HAVE MAINTAINED SLIGHT CHANCE POPS FOR NOW. THE BEST CHANCE FOR PRECIPITATION THROUGH THE NEXT SEVERAL DAYS WILL BE ON THURSDAY AS A COLD FRONT SLIDES THROUGH THE AREA. TIMING OF THE FRONT IS STILL A LITTLE UNCERTAIN...BUT HAVE MAINTAINED HIGHEST POPS IN THE EASTERN PORTION OF THE CWA AS THE FRONT APPEARS TO MOVE THROUGH IN THE LATE AFTERNOON AND EVENING HOURS WHEN THE INSTABILITY IS THE BEST. HIGH TEMPERATURES WILL BE A SHADE BELOW NORMAL FOR THE FIRST FEW DAYS THIS WEEK WITH COOL DRY AIR IN PLACE ACROSS THE AREA. HOWEVER...BY WEDNESDAY TEMPERATURES WILL BE NEAR NORMAL TO SLIGHTLY ABOVE NORMAL WITH 850 HPA TEMPS WARMING TO 15-20 DEGREES C. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ MG sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 930 AM EDT MON AUG 22 2005 .DISCUSSION... LATEST RUC AND NAM SHOW A SHORT-WAVE MOVING EAST ACROSS THE TENNESSEE VALLEY THIS AFTERNOON. CONVECTION ACROSS WESTERN AND MIDDLE TENNESSEE IS ASSOCIATED WITH THIS WAVE. COLD FRONT/DEWPOINT GRADIENT IS LOCATED NEAR THE TYS AREA WHICH WILL HELP TO FOCUS CONVECTION LATER THIS AFTERNOON. NAM SOUNDINGS SHOW AIRMASS ACROSS THE CHA AREA MODERATELY UNSTABLE WITH CAPES BETWEEN 2000 AND 2500 J/KG WITH LIFTED INDICES OF -6 TO -7. MAIN CONCERN WITH CONVECTION WILL BE DAMAGING DOWNBURSTS WINDS AND LOCALIZED FLASH FLOODING. WILL UP POPS SOUTH TO 50-60 PERCENT...BUT KEEP SOUTHWEST VIRGINIA DRY. HAVE A GOOD AFTERNOON. && .MRX WATCHES/WARNINGS/ADVISORIES... NC......NONE. TN......NONE. VA......NONE. && $$ DH tn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 343 AM EDT TUE AUG 23 2005 .DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE HIGH AND LOW TEMPERATURES TODAY AND TONIGHT. THE WATER VAPOR IMAGERY AND RUC/ETA SHOWING A CLOSED LOW OVER SOUTHERN QUEBEC....A RIDGE STRETCHING FROM MINNESOTA TO SOUTHERN HUDSON BAY...AND A LONGWAVE TROUGH DIGGING INTO BRITISH COLUMBIA. SURFACE ANALYSIS DEPICTS A LARGE RIDGE OVER ONTARIO AND THE UPPER GREAT LAKES. A LOW IS DEVELOPING OVER THE NORTHERN HIGH PLAINS... WITH A COLD FRONT EXTENDING NORTHEAST TO ANOTHER LOW OVER WESTERN HUDSON BAY. AN 850MB THERMAL TROUGH RUNS FROM SOUTHEAST ONTARIO THROUGH THE FORECAST AREA WITH TEMPERATURES AROUND 8C. THE MID LEVEL RIDGE WILL REMAIN OVER ONTARIO AND LAKE SUPERIOR. A WEAK SHORTWAVE WILL SWEEP THROUGH THE FORECAST AREA THIS MORNING. THE SURFACE RIDGE WILL REMAIN ANCHORED OVER THE UPPER GREAT LAKES. MEAN SURFACE-500MB RH WILL BE LESS THAN 40 PERCENT. THESE CONDITIONS WILL CONTINUE THROUGH WEDNESDAY. TRAJECTORY FORECAST INDICATE THAT THE AIR MASS OVER EAST CENTRAL ONTARIO YESTERDAY WILL MOVE OVER THE FORECAST AREA TODAY. THE 850MB THERMAL TROUGH WILL SLIP TO THE SOUTHEAST LEAVING THE 850MB TEMPERATURES ABOUT 2C WARMER THAN YESTERDAY. HIGH TEMPERATURES WERE IN THE MID 60S ACROSS MUCH OF THE FORECAST AREA EXCEPT FOR AROUND 70 OVER THE SOUTH PART OF THE CWA ON MONDAY. SOUNDING FORECAST INIDCATE THAT THERE WILL BE A MOIST LAYER AROUND 850MB TODAY WITH STEEP LAPSE RATE BELOW THIS LEVEL AND A SIGNIFICANT CAP ABOVE. THUS EXPECT TO SEE SOME CU DEVELOP OVER THE SOUTHERN COUNTIES AND ALONG THE WISCONSIN BORDER. GFS IS A 10 PERCENT DRIER OVER THE SAME LOCATIONS AT THE 850MB LEVEL. THUS WILL FAVOR LOW 70S FOR A HIGH TODAY. 850MB TEMPERATURES WILL RISE ANOTHER 2C OVER THE FORECAST AREA ON WEDNESDAY. ETA/GFS INDICATE THAT THE AIR MASS WILL BE DRIER THAN THIS MORNING. BOTH MODELS ALSO INDICATE THAT SURFACE DEW POINTS WILL BE IN THE UPPER 40S ACROSS THE AREA. WITH DRIER CONDITION ALOFT AND LIGHT WINDS...STILL LOOKING FOR A FAIR AMOUNT OF RADIATIONAL COOLING. THUS WILL BE LOOKING FOR OVERNIGHT LOW TEMPERATURES IN THE UPPER 40S. 850MB TEMPERATURES IS EXPECTED TO BE AROUND 2C WARMER ON WEDNESDAY THAN TUESDAY'S TEMPERATURES. WINDS WILL REMAIN LIGHT SO MIXING WILL BE MINIMAL. HOWEVER...ETA/GFS INDICATE THAT THE 850MB TEMPERATURE WILL BE GREAT THAN 70 PERCENT OVER THE WESTERN U.P. SUGGESTING A CU DEVELOPMENT. THE MID LEVEL RIDGE WILL SHIFT INTO EASTERN ONTARIO ON WEDNESDAY NIGHT AS WILL THE SURFACE RIDGE. A WEAK SHORTWAVE TRAVERSING THE RIDGE WILL SWING INTO THE WISCONSIN AND WESTERN U.P. A SURFACE LOW ILL MOVE INTO INTO WESTERN MANITOBA. AN ACCOMPANYING COLD FRONT WILL STRETCH FROM THIS LOW THROUGH THE DAKOTAS TO A LOW OVER WESTERN NEBRASKA. THE AIR MASS WILL CONTINUE DRY OVER THE FORECAST AREA. SHOWERS AND THUNDERSTORMS WILL BE ASSOCIATED WITH THE FRONTAL SYSTEM OVER THE DAKOTAS. THE SHORTWAVE WILL NAVIGATE THROUGH THE FORECAST AREA ON THURSDAY. THE COLD FRONT WILL PUSH EAST INTO WESTERN MINNESOTA ON THURSDAY. ISENTROPIC ASCENT AHEAD OF THE FRONT AND ACCOMPANY SHORTWAVE ENERGY SHOULD GENERATE OF THUNDERSTORMS WEST OF THE FORECAST AREA. ANOTHER SHORTWAVE WILL SPIN THROUGH UPPER MICHIGAN THURSDAY NIGHT. THE SURFACE RIDGE WILL SLOWLY BE PUSHING EAST. THE AIR MASS WILL CONTINUE TO BE DRY SO DO NOT EXPECT ANY PRECIPITATION WITH THIS SHORTWAVE. THE COLD FRONT WILL EXTEND FROM A LOW OVER NORTHERN ONTARIO THROUGH EASTERN MINNESOTA TO A LOW OVER KANSAS BY 12Z FRIDAY. AN MID LEVEL LOW WILL DIG INTO MANITOBA ON FRIDAY. A SHORTWAVE PINWHEELING AROUND THIS LOW WILL SWING INTO WESTERN UPPER MICHIGAN ON FRIDAY AS AN ACCOMPANYING COLD FRONT SLIDES INTO WESTERN LAKE SUPERIOR AND CENTRAL WISCONSIN. ISENTROPIC ASCENT AHEAD OF THE FRONT WILL BE WEAK OVER UPPER MICHIGAN. Q-VECTOR ANALYSIS INDICATE THAT THE STRONGEST CONVERGENCE WILL SLIDE TO THE NORTH OF THE FORECAST AREA...HOWEVER...THERE WILL BE ENOUGH OVER THE AREA TO STILL PRODUCE CONSIDERABLE INSTABILITY. MOST OF THE LOW LEVEL MOISTURE ACCOMPANYING THE FRONT WILL SHIFT TO THE NORTHEAST AS WELL. HOWEVER...THERE APPEARS TO BE A WEAK BAND THAT WILL CROSS THE AREA AS WELL. CONDITIONS LOOK FAVORABLE FOR AT LEAST A CHANCE OF SHOWERS AND THUNDERSTORM DEVELOPMENT. THE MID LEVEL LOW WILL RELOCATE OVER NORTHERN ONTARIO FRIDAY NIGHT. SHORTWAVE ENERGY WILL SHIFT ACROSS THE FORECAST AREA. THE COLD FRONT WILL REACH EASTERN U.P. BY SUNRISE. ISENTROPIC ASCENT AND MOISTURE WILL SHIFT AHEAD OF THE FRONT. GFS INDICATES BY 12Z THE SYSTEM WILL MOVE EAST OF THE FORECAST AREA AND NVA ENERGY WILL SETTLE OVER THE AREA. && .MQT...WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 320 AM EDT TUE AUG 23 2005 .SHORT TERM /TODAY THROUGH WED NIGHT/...NAM/GFS/RUC ALL SHOW SOME UPPER VORT ENERGY HANGING ACROSS PORTIONS OF SC/GA EARLY THIS MORNING. IT IS TAPPING INTO SOME VERY UNSTABLE AIR ACROSS SC WITH LATEST MSAS SHOWING LIS FROM -4 TO -6. NOT MUCH ACTIVITY RIGHT NOW IN GA AS LAST NIGHTS CONVECTION LASTED LATE INTO THE EVENING OVER SOUTHERN GA...SO AREA IS FAIRLY STABLE RIGHT NOW. THIS SC CONVECTION WILL LIKELY CONTINUE THROUGH THE PREDAWN HOURS AND MOVE OUT OF THE CWA AFTER SUNRISE. PLENTY OF BOUNDARIES WILL REMAIN WITH THE MODELS SHOWING THE UPPER VORT TO MOVE LITTLE. AFTER A BRIEF RECOVERY PERIOD LOOK FOR LIKELY POPS TODAY ALL ZONES AS DAYTIME HEATING/BOUNDARIES AND UPPER ENERGY HELPS TO INITIATE STORMS. LIKE WE SAW YESTERDAY THERE IS A THREAT OF SOME ISOLATED SEVERE STORMS TODAY. WESTERLY FLOW ALOFT WILL ALLOW FOR SOME MIDLAND STORMS TO MOVE INTO THE CWA. MANY OF THE STORMS TODAY WILL BE GENERATED BY BOUNDARY COLLISIONS AND OVERALL MOVEMENT OF STORMS WILL BE DIFFICULT TO ASCERTAIN. MOSTLY CLOUDY WILL PREVAIL WITH PLENTY OF DEBRIS CLOUDS. THERE MAY BE ENOUGH POCKETS OF SUN SOMETIME DURING THE LATE MORNING/EARLY AFTERNOON TO WARM INTO THE LOWER 90S. CHC POP OVERNIGHT WITH LINGERING CONVECTION. UPPER WAVE OVER THE GREAT LAKES WILL DIG SOUTHEAST...HELPING TO FORM A WEAK SFC LOW OFF THE NC COAST ON WED AND WED NIGHT. THE FRONT WILL THEN MAKE A PUSH SOUTH WITH THE GFS SHOWING SOME WEAK NE WINDS BY WED AFTERNOON. POPS WILL BEGIN TO TAPER OFF FROM N TO S AS LI FORECASTS SHOW STABLE AIR MOVING SOUTHWARD. FRONT SHOULD PUSH SOUTH OF THE CWA WED NIGHT...BUT WITH THE FRONT STILL IN THE GENERAL AREA WILL KEEP CHC POP. LOOK FOR DEWPOINTS AND TEMPS TO LOWER SLIGHTLY UNDER THE INFLUENCE OF HIGH PRESSURE BUILDING IN OVER THE SC ZONES. && .LONG TERM /THU THROUGH MONDAY/...CHC POP GETS PUSHED SOUTH INTO THE FAR SOUTHERN GA ZONES ON THU WITH ALL AREAS SEEING SLIGHT POP OVER THE WEEKEND INTO EARLY NEXT WEEK UNDER THE INFLUENCE OF EAST COAST SFC HIGH PRESSURE AREA. MEAN RH FORECASTS AND THE FACT THAT WE WILL BE SEEING SOME E/NE WINDS MAY KEEP SOME SEABREEZE CONVECTION OVER THE AREA. NO MAJOR CHANGES MADE TO TEMPS. && .MARINE...SFC TROUGH IS IN PLACE ALONG THE GA/SC COAST THIS MORNING...IS EXPECTED TO REMAIN NEARLY STATIONARY THROUGH EARLY WED. THIS WILL RESULT IN A GENERAL SOUTHERLY FLOW ACROSS THE WATERS...AOB 15 KTS THROUGH EARLY WED. THE TROUGH OF LOW PRESSURE WILL SHIFT EAST OF THE COASTAL WATERS WED...AS AN AREA OF HIGH PRESSURE BEGINS TO BUILD SOUTHWARD INTO THE MID ATLANTIC STATES. AS HIGH PRESSURE BUILDS INTO THE COASTAL WATERS...WINDS WILL SHIFT FROM THE SE TO THE NE. MODELS CONTINUE TO INDICATE A WAVE OF LOW PRESSURE OR TROPICAL SYSTEM PASSING WELL SOUTH OF THE AREA...BUT PINCHED GRADIENT FLOW BETWEEN HIGH PRESSURE TO THE NORTH AND LOW TO THE SOUTH...IS EXPECTED TO INCREASE WINDS INTO THE 15 TO 20 KT RANGE ACROSS THE COASTAL WATERS THU THROUGH SAT. SEAS ARE EXPECTED TO RESPOND TO FAVORABLE NE FETCH...WITH 4 TO 6 FT SEAS ACROSS THE WATERS LATE THU THROUGH SAT. SCA CONDITIONS FOR HAZARDOUS SEAS WILL LIKELY BE MET THU NIGHT THROUGH SAT ACROSS THE WATERS. && .AVIATION...DIFFICULT AVIATION FORECAST THIS MORNING...WITH SHORTWAVE DISTURBANCE SWINGING THROUGH THE AREA...ALONG WITH FRONTAL BOUNDARY DRAPED ALONG THE SC/GA COAST. SHWRS/TSTMS HAVE ALREADY DEVELOPED IN UNSTABLE AIRMASS ASSOCIATED WITH COLD POCKET ALOFT. WILL INCLUDE TEMPO GROUP FOR TSRA AT CHS TERMINAL FROM 08Z THROUGH 10Z...WITH VCTS LINGERING THROUGH 12Z. AT SAV TERMINAL...EXPECT THE MORNING TO BE QUIET WITH STRONG NVA IN WAKE OF SHORTWAVE. WILL KEEP MVFR VSBY/S GOING THROUGH MID MORNING AT CHS TERMINAL. EXPECT SHWRS/TSTMS TO DEVELOP AGAIN THIS AFTERNOON...WITH AID OF DAYTIME HEATING...SEA BREEZE DEVELOPMENT AND FRONTAL BOUNDARY LINGERING IN THE AREA. WILL INCLUDE TEMPO GROUP FOR TSRA BETWEEN 16Z AND 20Z AT BOTH TERMINALS...AND VCSH FROM 20Z TO 23Z. EXPECT MVFR VSBY/S WILL RETURN TO THE TERMINALS ONCE AGAIN TONIGHT. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. && $$ PY/JRJ sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HANFORD CA 852 AM PDT TUE AUG 23 2005 .SHORT TERM...FOR THE CENTRAL CALIFORNIA INTERIOR...SATELLITE PICTURES INDICATE CLEAR SKIES OVERHEAD WITH SURFACE OBS SHOWING 24 HOUR TEMPERATURE TRENDS NEAR PERSISTENCE IN THE MOUNTAINS AND DESERTS, AND A BIT HIGHER IN THE VALLEY. LOW LEVEL SOUNDING DATA SUPPORT SEVERAL DEGREES OF AIRMASS WARMING, AND THE CURRENT FORECAST DETAILING SLIGHTLY WARMER MAXES LOOKS FINE. ALTHOUGH THE MORNING RENO SOUNDING SHOWS A MORE STABLE AIRMASS THIS MORNING, THE NAM/RUC DOES INDICATE SOME AFTERNOON INSTABILITY ALONG THE CREST. WILL OPT NOT TO INSERT THUNDER INTO THE FORECAST AT THIS TIME DUE TO THE LACK OF AN APPARENT TRIGGERING MECHANISM, BUT WILL HAVE TO WATCH. RATHER UNEVENTFUL PATTERN SHAPING UP THE NEXT COUPLE OF DAYS WITH TEMPERATURES NEAR OR SLIGHTLY ABOVE AVERAGE. MAY SEE A SOMEWHAT GREATER ONSHORE FLOW DEVELOPING LATE WEDNESDAY INTO THURSDAY AS A WEAK LOW DEVELOPS OFF THE NORCAL COAST, WHICH MAY PROVIDE A COUPLE OF DEGREES OF COOLING FOR THE LOWER ELEVATIONS. ELSEWHERE, LITTLE CHANGE IS INDICATED THROUGH THE PERIOD. NO UPDATES TO THE FORECAST THIS MORNING. .LONG TERM...PREVIOUS DISCUSSION FOR THURSDAY NIGHT THROUGH MONDAY... IN THE SHORT TERM A BAGGY TROUGH WILL SUPPRESS A HIGH PRESSURE RIDGE TOWARDS SOUTH CALIFORNIA MAINTAINING A WEAK WESTERLY FLOW ALOFT. THIS SHOULD RESULT IN A BENIGN WEATHER PATTERN WITH TEMPERATURES SLIGHTLY ABOVE SEASONAL LEVELS. LOTS OF VARIANCE IN THE MEDIUM RANGE MODELS TOWARDS THE LATTER PART OF THE EXTENDED PERIOD. THUS DO NOT HAVE A HIGH DEGREE OF CONFIDENCE FOR THE SUNDAY AND MONDAY. THE GENERAL CONSENSUS OVER CALIFORNIA IS BETWEEN THE ECWMF AND CAN GEM WHICH PROG A STRONGER UPPER LEVEL SHORT TO MOVE THROUGH THE PACIFIC NORTHWEST DIGGING WELL SOUTH INTO CENTRAL CALIFORNIA. IN CONTRAST THE GFS PROGS A BENIGN WESTERLY FLOW ALOFT OVER CALIFORNIA AND APPEARS TO BE SHEAR OUT THE UPPER LEVEL ENERGY OVER BRITISH COLOMBIA AND PAC NW. UNTIL BETTER MODEL CONSENSUS WILL INDICATE ONLY A SLIGHT COOLING TREND FOR NOW DURING THE LATER PART OF THE PERIOD. && .AVIATION...VFR CONDITIONS WILL PREVAIL THROUGH AT LEAST 18Z WEDNESDAY. MORE SPECIFICS CAN BE FOUND IN THE TAFS FOR KMCE...KFAT AND KBFL. && .HNX...WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WWW.WEATHER.GOV/HANFORD /USE ALL LOWER CASE/ BURGER/MV ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 1000 AM EDT TUE AUG 23 2005 .DISCUSSION...THE EAST COAST TROUGH IS BECOMING MORE AMPLIFIED AND RUC ANALYSIS SHOWS A STRONG VORT OVER THE FLORIDA PANHANDLE. THE INCREASING INSTABILITY ALONG WITH AFTERNOON HEATING SHOULD PROVIDE GOOD COVERAGE OF THUNDERSTORMS ACROSS THE LOCAL REGION. MAX TEMPS SHOULD ALSO BE SLIGHTLY LOWER TODAY. && .MARINE...WILL REMOVE MORNING WORDING FOR THUNDERSTORMS ON THE UPDATE. OTHERWISE...NO CHANGES EXPECTED. && .AVIATION...WE STILL HAVE SOME PATCHY BR/HZ ALONG WITH STRATUS PRODUCING MVFR/IRF CONDITIONS OVER SE AL. OTHERWISE...EXPECT SCT TO NMRS TSRA TO DEVELOP THIS AFTERNOON ACROSS MUCH OF THE AREA WITH LOCAL MVFR/IFR CRITERIA IN HEAVY RAIN. && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. && $$ BARRY fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 1118 AM EDT TUE AUG 23 2005 .MORNING UPDATE... VERY MINOR CHANGES MADE TO FORECAST THIS MORNING. CURRENT GRIDS RIGHT ON TRACK. STILL A SMALL CHANCE FOR CONVECTION TO DEVELOP ACROSS EXTREME SOUTHERN KENTUCKY AS A WEAK FRONTAL BOUNDARY STILL EXISTS ACROSS SOUTHERN FA. CURRENTLY THERE IS A 10-DEGREE DEWPOINT GRADIENT BETWEEN LOUISVILLE AND BOWLING GREEN...WITH UPPER 50 DEWS NORTH AND MID TO UPPER 60 DEWS SOUTH (THIS BOUNDARY IS RESOLVED IN RADAR IMAGERY JUST NORTH OF BOWLING GREEN). WATER VAPOR IMAGERY SHOWS WEAK MID-LEVEL DISTURBANCE OVER SOUTHEAST MO AND SOUTHERN IL...CO-LOCATED WITH RUC LIFTED INDICES OF -2. THESE DYNAMICS/INSTABILITY WILL LIKELY TRAVERSE ACROSS TN/KY BORDER AND SPARK A FEW STORMS OVER SOUTHERN CWA. BUT WITH UPPER TROUGH DIVING SOUTHWARD...TIMING OF ANY CONVECTION WILL BE AROUND THE 3-5 PM EDT RANGE...IF AT ALL...BEFORE IT RACES SOUTHEASTWARD INTO TENNESSEE. UPDATE OUT SOON. AL && LMK WATCHES/WARNINGS/ADVISORIES... .IN...NONE. .KY...NONE. && $$ JARVIS ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI ISSUED BY NATIONAL WEATHER SERVICE MARQUETTE MI 1040 AM EDT TUE AUG 23 2005 .DISCUSSION... NO SUBSTANTIVE CHANGES NEEDED TO THE GOING FORECAST FOR TODAY. LATEST VISIBLE IMAGERY SHOWS QUITE A FEW CLOUDS LINGERING OVER THE CWFA THIS MORNING...WITH SOME DIURNAL CU ALREADY DEVELOPING. 12Z RUC SUGGESTS A SLOW DRYING IN THE 925-850MB LAYER THROUGH THE DAY AS THE LOW LEVEL THERMAL TROUGH SLIDES SLOWLY EAST. WOULD EXPECT SOME DIURNAL CU TO INITIALLY FILL IN MANY OF THE GAPS INT THE CLOUD COVER...WITH A SLOW REDUCTION IN CLOUD COVER FROM NORTHWEST TO SOUTHEAST DURING THE MID TO LATE AFTERNOON. GOING FORECAST HAS THESE TRENDS IN HAND FAIRLY WELL...SO UPDATE WITH MAINLY BE COSMETIC. TEMPERATURES HAVE QUICKLY REBOUNDED INTO THE LOWER TO MIDDLE 60S...AND EXPECT READINGS TO MAX OUT IN THE LOWER 70S...WHICH MATCHES UP REASONABLY WELL WITH EXPECTED MIXING FROM A BLENDED 12Z APX/GRB SOUNDING. UPDATED ZFP WILL BE OUT SHORTLY. && .PREV DISCUSSION (LATER PERIODS)... TONIGHT THROUGH THURSDAY NIGHT...SFC HIGH OVER EASTERN UPPER TONIGHT THEN SHIFTING SLOWLY EAST AS UPPER LEVEL PATTERN SLOWLY AMPLIFIES. AIR MASS WILL BECOME VERY DRY WITH H8-H5 RH'S DOWN INTO THE 10% RANGE THROUGH THURSDAY MORNING. SFC HIGH DOES SHIFT SLIGHT EAST OF US...BUT WIND FLOW WILL BE DECOUPLED AT THE SFC...AND LESS THAN 10 KTS TO H8. WITHOUT ANY CLOUDS EXCEPT FOR POSSIBLE CIRRUS ARRIVING LATE WEDNESDAY NIGHT...TEMPS SHOULD PLUMMET AGAIN. WILL GO LOWER THAN MOS AGAIN ACROSS THE SE...IN THE LOWER HALF OF THE 40S...WITH WARMEST READINGS ACROSS EASTERN UPPER WHERE SE FLOW COMING OFF THE LAKES/CIRRUS WILL KEEP THINGS AROUND 50. MAY HAVE TO TAKE A LOOK AT THESE TEMPS...AS IF ANYTHING...WOULD EXPECT COOLER OVERNIGHT LOWS. INITIAL SHORTWAVE IMPULSES WORK INTO THE RIDGE THURSDAY AFTERNOON AND FRIDAY. THESE FEATURES WILL DO HARDLY ANYTHING...EXCEPT MAYBE BRING IN A TOUCH MORE HIGHER LEVEL CLOUD. AIR MASS WILL BE SO DRY INITIALLY THAT SIGNIFICANT CLOUD COVER SEEMS VERY LIKELY. HIGH TEMPS DURING THIS TIME...GENERALLY THE UPPER HALF OF THE 70S. FRIDAY AND INTO THE WEEKEND...ALTHOUGH NOT MUCH TIME TO LOOK AT THESE PERIODS...PATTERN NOT VERY SUGGESTIVE OF A CHANCE FOR PRECIP. UPPER TROUGH LOOKS A BIT FAR TO THE NW...SOME FORCING SNEAKING ACROSS THE NRN CWA. ASSOCIATED SFC FRONT LOOKS TO TRY AND WASH OUT AS THE SFC HIGH FIGHTS TO STAY AROUND. MOISTURE PROFILES DO NOT LOOK EXCEPTIONAL EITHER. PER COORDINATION WITH SURROUNDING OFFICES...HAVE KEPT CHANCES IN FOR FRIDAY AFTERNOON AND FRIDAY NIGHT...AS I SUPPOSE THE TERM CHANCE...DOES APPLY...EVEN IF IT LOOKS SMALL. SMD && .APX...WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 410 AM MDT TUE AUG 23 2005 .DISCUSSION...CURRENT SURFACE ANALYSIS SHOWS AREA OF LOW PRESSURE OVER EASTERN MT WITH SURFACE TROF STRETCHING SOUTHWARD ACROSS EASTERN WY. SOUTHERLY WINDS ACROSS THE AREA KEEPING TEMPS MILD AND CONTINUING TO BRING IN LOW LEVEL MOISTURE. FOG LOOP SHOWS LOW CLOUDS AND PATCHY FOG CREEPING NORTHWARD INTO SOUTH CENTRAL SOUTH DAKOTA. RUC AND NAM BOTH SUGGEST THE LOW CLOUDS WILL MAKE IT AS FAR NORTH AND WEST AS PHP AND IEN THIS MORNING...SO WILL KEEP AN EYE ON IT. OTHERWISE... REGIONAL RADARS SHOW SOME SHOWERS AND STORMS ACROSS EASTERN MT ASSOCIATED WITH LOW LEVEL JET AND THETA-E RIDGE. OTHER LIGHTER SHOWERS AROUND THE MTS OF WY AS WELL. FOR TODAY...SKIES WILL GENERALLY BE PARTLY CLOUDY THRU MOST OF THE DAY...EXCEPT FOR LOW CLOUDS LINGERING ACROSS SOUTHEAST CWA THIS MORNING. HIGHS WILL MOSTLY BE IN THE 80S. UPPER LOW WILL MOVE ACROSS THE CANADIAN ROCKIES TODAY...WITH SOUTHWEST FLOW ALOFT OVER THE REGION. SERIES OF SHORTWAVES NOTED ON WATER VAPOR NEAR AND DOWNSTREAM OF US. FIRST ONE OVER NEB WILL BRING A CHANCE OF STORMS TO SC SD BY EARLY AFT AS ATMOS DESTABILIZES. ANOTHER WAVE OVER WESTERN WY SHOULD REACH NORTHEAST WY AND THE HILLS THIS AFT. BEST INSTABILITY THIS AFTERNOON WILL BE AHEAD OF SURF TROF...SOUTH AND EAST OF THE BLACK HILLS. SHEAR NOT REAL IMPRESSIVE...LOOKING BEST ACROSS SOUTHERN SD. THERE WILL BE SOME STRONG TO MARGINALLY SEVERE STORMS ACROSS THE AREA THIS AFT AND EVE. LARGE HAIL SHOULD BE THE MAIN THREAT OVER THE HILLS AND POINTS TO THE EAST...WHILE STRONG WINDS SHOULD BE MORE OF A THREAT ACROSS NORTHEAST WY. RIGHT MOVING SUPERCELLS ARE NOT FORECAST TO MOVE MUCH...SO HEAVY RAIN MAY BECOME A CONCERN...ESPECIALLY FROM THE HILLS EASTWARD...WITH PRECIPITABLE WATER AOB 1 INCH. EXPECT MOST OF THE ACTIVITY TO MOVE EAST OUT OF THE AREA DURING THE OVERNIGHT. ON WEDNESDAY...COLD FRONT WILL FINALLY NUDGE SOUTHEAST INTO THE AREA AND MORE OR LESS STALL OVER NORTHWEST SD AND NORTHEAST WY DURING THE DAY. THIS FRONT WILL BE THE FOCUS FOR MORE SHOWERS AND STORMS WED AFT AND NIGHT...ESPECIALLY OVER NORTHERN SD. RISK FOR SEVERE STORMS EXPECTED ACROSS THAT AREA AS WELL...WHERE BEST SHEAR WILL BE IN PLACE. FRONT WILL SLOWLY PROGRESS BY THURSDAY MORNING TO SOUTH CENTRAL SD AND THEN IS EXPECTED TO STALL OVER THAT AREA DURING THE DAY. WILL KEEP BEST CHANCE FOR PCPN OVER THERE...BUT ALSO KEEP A LOW CHANCE FOR INSTABILITY SHOWERS ACROSS MUCH OF WESTERN SD. THE SYSTEM SHOULD FINALLY EXIT THE REGION THURSDAY NIGHT WITH FRIDAY LOOKING TO BE A RATHER NICE DAY...WITH HIGHS MOSTLY IN THE UPPER 70S AND LOWER 80S. EXTENDED...ZONAL FLOW SETS UP FOR SAT THRU MON AS FLAT UPPER RIDGE WILL DOMINATE THE WX. THIS WL MEAN NEAR...OR SLIGHTLY ABV NORMAL TEMPS AND DRY WEATHER FOR SAT-MON. FLOW WILL TURN MORE SWRLY BY MON NITE AS UPPER TROF BEGINS TO DIG OVER NWRN CONUS...THIS IN TURN WILL BRING A CHC OF TSTMS TO THE AREA BY TUES/WED OF NEXT WEEK. && .AVIATION...VFR CONDS ARE EXPECTED TO CONT THRU THE FCST PERIOD ALONG ALL TWEB RTES AND AT THE TAF SITES...WITH THE EXCEPTION OF SRN PORTIONS OF TWEB RTE 258 ACRS WRN NEB WHERE AREAS OF MVFR CONDS DUE TO VSBYS/CIGS IN FOG ARE POSSIBLE THRU 15Z... S-SE WINDS WILL INC TO 15 TO 25 MPH BY 18Z. SCT TSTMS ARE POSSIBLE THIS AFT...MAINLY AFT 18Z. && .UNR...WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. && $$ ST/LJC sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 229 PM MDT TUE AUG 23 2005 .SHORT TERM... (TONIGHT AND WEDNESDAY) MAIN CONCERNS REMAIN THUNDERSTORM COVERAGE ACROSS THE REGION WITH SEVERE POTENTIAL ACROSS THE PLAINS THIS EVENING. CURRENT WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSIS INDICATING SHORT WAVE TROUGH AND ASSOCIATED 60KT JET CORE MOVING INTO CENTRAL COLORADO ATTM. REGIONAL RADARS INDICATING SCATTERED TSRA ACROSS NW COLORADO AND NEW MEXICO ASSOCIATED WITH LF AND RR QUAD OF JET...WITH MAINLY ISOLATED STORMS FIRING ACROSS THE SOUTHERN AND CENTRAL MTS ATTM. AT THE SFC...LEE TROUGHING ACROSS THE I-25 CORRIDOR KEEPING MOIST EASTERLY UPSLOPE FLOW IN PLACE ACROSS THE EASTERN PLAINS WITH DEW PTS IN THE MID 50S TO LOWER 60S ATTM. MORNING LOW CLOUDS ACROSS THE FAR SE PLAINS...ALONG WITH INTERMITTENT MID AND HIGH LEVEL CLOUDS HAVE TEMPERED HIGHS SOMEWHAT TODAY...WITH TEMPERATURES IN THE MID 70S TO LOWER 80S ACROSS THE PLAINS ATTM. TONIGHT...SHORT WAVE TROUGH CONTINUES TO MOVE ACROSS THE STATE WITH QC IMPLIED ASCENT MOVING ACROSS EASTERN COLORADO THIS EVENING AND INTO WESTERN KANSAS OVERNIGHT. MODELS SOUNDINGS INDICATING RATHER UNSTABLE ENVIRONMENT IN PLACE...WITH CAPES BETWEEN 1000-1500 J/KG ACROSS THE I-25 CORRIDOR AND AROUND 2000-2500 J/KG ACROSS THE FAR SE PLAINS...HOWEVER SOUNDINGS ALSO INDICATING RATHER HEALTHY MID LEVEL CAP IN PLACE...WITH CINS BETWEEN 100-200J/KG AS WELL. AT ANY RATE...WITH SOME LIFT WITH PASSING WAVE...WILL SEE ISOLATED TO SCATTERED TSRA DEVELOP AND MOVE ACROSS THE HIGHER TERRAIN AND HIGH MT VALLEYS LATE THIS AFTERNOON AND EVENING...DECREASING THEREAFTER WITH SUBSIDENCE BEHIND WAVE. WITH LOADED GUN TYPE SOUNDINGS IN PLACE ACROSS THE EASTERN PLAINS...ALONG WITH ANOTHER FEW HOURS OF SUN TIME TO MEET CONVECTIVE TEMPERATURES IN THE LOWER TO MID 80S AND LIFT FROM PASSING WAVE...EXPECT TO SEE SCATTERED TSRA DEVELOP LATE THIS AFTERNOON AND EVENING ACROSS THE I-25 CORRIDOR...MOVING ACROSS THE EASTERN PLAINS WITH MCS DEVELOPING AND MOVING INTO WESTERN KANSAS OVERNIGHT. WITH BULK SHEARS AROUND 30-40KTS...DOWNDRAFT CAPES AROUND 1500J/KG AND THE BULK OF CAPE IN THE HAIL GROWTH ZONE (-10C TO -20C)...COULD SEE A FEW SEVERE STORMS PRODUCING HAIL TO AROUND 1 INCH AND GUSTY WINDS IN EXCESS OF 60 MPH ACROSS THE PLAINS AS WELL. WITH WESTERLY FLOW...STORMS WILL BE MOVING TODAY WITH FLASH FLOODING THREAT LOW...HOWEVER...WILL STILL SEE LOCALLY HEAVY RAINS WITH AMPLE MOISTURE IN PLACE. WEDNESDAY...SHORT WAVE CONTINUES TO MOVE ACROSS THE NORTHERN HIGH PLAINS WITH WARMER AND DRIER WESTERLY FLOW MOVING ACROSS THE REGION. HAVE KEPT MOSTLY CLOUDY WORDING ACROSS THE FAR SE PLAINS...WITH MVFR AND PATCHY IFR STRATUS LIKELY FROM MCS OUTFLOW. STILL LOOKS TO BE ENOUGH MOISTURE FOR SOME ISOLATED CONVECTION ACROSS THE HIGHER TERRAIN...AND ACROSS THE SOUTHER TIER ZONES...WHERE MODELS INDICATING SOME LIFT ASSOCIATED WITH MINOR JET STREAK EMBEDDED IN THE FLOW. -MW .LONG TERM... (THURSDAY THROUGH TUESDAY) I DID NOT MAKE ANY SIGNIFICANT CHANGES TO THE LONG TERM FORECAST IN WHICH I INHERITED. MAIN CHANGES WERE PRIMARILY TO FINE TUNE THE BEGINNING AND ENDING TIMES OF CONVECTIVE PRECIPITATION DURING THE AFTERNOON AND EVENING TIME PERIODS. WE WILL HAVE TO KEEP AN EYE ON THE THU-SAT TIME PERIODS. MAIN SHORT WAVE MOVING IN ZONAL FLOW TO OUR NORTH SHOULD NOT INFLUENCE OUR WX TOO SIGNIFICANTLY...BUT IF THIS FEATURE DROPS A BIT FARTHER SOUTH OR IF THE SFC HIGH IS A BIT STRONGER...THEN A FRONT MAY PUSH DOWN HERE A BIT MORE AGRESSIVELY AND THIS MAY IN TURN TAPER TEMPS DOWN A FEW DEGREEES DURING THIS TIME PERIOD. THIS WOULD ALSO INCREASE OUR CHANCES OF PRECIP FOR THIS TIME PERIOD.\/HODANISH && .PUB WATCHES/WARNINGS/ADVISORIES...NONE. && $$ co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 303 PM EDT TUE AUG 23 2005 .SHORT TERM (TONIGHT AND WEDNESDAY)... CURRENT WATER VAPOR IMAGERY STILL SHOWING DEEP TROUGH OVER THE NORTHEAST UNITED STATES WITH STRONG VORT MAX ROTATING AROUND SOUTHWEST EDGE ACROSS INDIANA AND OHIO. SFC HIGH PRESSURE CONTINUES TO SLOWLY SAG SOUTHWARD TOWARD THE REGION FROM UPPER GREAT LAKES. WEAK INSTABILITY AXIS STILL LOCATED ACROSS FAR SOUTH-CENTRAL KENTUCKY...WHERE RUC ANALYSES SHOW -2 TO -3 LIFTED INDICES. CU FIELD ALSO ALREADY DEVELOPED...ALTHOUGH MOST EARLY CONVECTIVE DEVELOPMENT LOOKS TO BE SOUTH OF THE BORDER. WILL KEEP SLIGHT CHANCE POPS OVER SOUTHERN ONE TO TWO TIERS OF COUNTIES...AND THE REST OF THE FA DRY. ACARS DATA STILL SHOWING A BIT OF MID-LEVEL WARMING AND STEEP LOW-LEVEL LAPSE RATES CLOSE TO KY-TN BORDER. SO ANY ISOLATED CELLS THAT DEVELOP WILL BE BRIEF AND SHALLOW. AFTER SUNSET...ANY CONVECTION OVER THE SOUTHERN CWA WILL DISSIPATE QUICKLY. WILL THEN KEEP ENTIRE CWA DRY THROUGH TOMORROW AS HIGH PRESSURE AND MUCH DRIER AIR THROUGH THE ENTIRE TROPOSPHERE DOMINATES THE REGION. WENT CLOSE TO GUIDANCE FOR OVERNIGHT LOWS...WHICH SHOULD DROP TO NEAR 60 DEGREES GIVEN EXPECTED RADIATIVE COOLING. WEDNESDAY WILL BE A VERY PLEASANT DAY WITH MOSTLY CLEAR SKIES. PROGGED THICKNESS VALUES AND 850MB TEMPS PER THE GFS AND NAM ARE A BIT LESS THAN VALUES THIS MORNING...SO WILL GO AT OR JUST BELOW GUIDANCE FOR TEMPS TOMORROW...ROUGHLY LOW 80S NORTH AND MID 80S SOUTH. AL .LONG TERM (WEDNESDAY NIGHT THROUGH TUESDAY)... MODELS SHOWING DECENT AGREEMENT AND RUN-TO-RUN CONTINUITY WITH ADVANCING 500HPA SHORTWAVE AND ASSOCIATED VORT MAX LATER THIS WEEK. AFTER MOVING ALONG THE U.S./CANADIAN BORDER THE DISTURBANCE PROCEEDS INTO THE GREAT LAKES FRIDAY AND OHIO VALLEY SATURDAY. MODELS SHOW THE SURFACE COOL FRONT ASSOCIATED WITH THIS UPPER SYSTEM IN VARYING DEGREES OF INTENSITY...BUT THEY GENERALLY AGREE THAT IT WILL CROSS THE PLAINS AND MIDWEST FRIDAY AND MOVE INTO INDIANA AND KENTUCKY BY SATURDAY IN A FAIRLY WEAK STATE. NEVERTHELESS...DEEP MOISTURE AND LIFT DO INCREASE NICELY AHEAD OF THE FRONT SO WILL UP THUNDERSTORM CHANCES A BIT FOR FRIDAY AND ESPECIALLY SATURDAY. TURNING ATTENTION TO THE TROPICS... YESTERDAY MODELS DEVELOPED A TROPICAL SYSTEM AROUND FLORIDA AND MOVED IT OFF TO THE WEST. AGAIN TODAY MODELS ARE SHOWING A TROPICAL SYSTEM IN THE VICINITY OF FLORIDA BY THE END OF THE WORK WEEK. WHILE THE GEM TAKES THIS SYSTEM NORTHWEST AND THEN NORTH...REACHING THE OHIO AND TENNESSEE VALLEYS MONDAY AND THE GREAT LAKES TUESDAY...THE ECMWF AND GFS ENSEMBLE MEAN TEND TO HANG IT UP OVER THE NORTHEAST GULF/SOUTHEAST UNITED STATES. EITHER WAY...WITH POTENTIAL OF AN OLD FRONT IN THE REGION PLUS WARM HUMID AIR MASS PLUS ADDITIONAL MOISTURE POSSIBLY COMING UP FROM THE GULF WILL NEED TO INCLUDE SMALL CHANCE POPS FOR THUNDERSTORMS INTO THE EARLY PART OF THE NEW WEEK. THIS WILL ALSO AGREE WELL WITH SURROUNDING NWS OFFICES. 13 && LMK WATCHES/WARNINGS/ADVISORIES... .IN...NONE. .KY...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBUQUERQUE NM 255 PM MDT TUE AUG 23 2005 .DISCUSSION... ACTIVE DAY IN STORE FOR THE FORECAST AREA AS SHOWERS/THUNDERSTORMS CONTINUE TO ERUPT OVER THE REGION...WITH MOISTURE AS WELL AS UPPER LEVEL ENERGY IN POSITION TO INTERACT WITH INCOMING SOLAR RADIATION. WATER VAPOR LOOP INDICATING MONSOONAL MOISTURE OVER NRN OLD MEXICO ON MONDAY HAS ADVECTED NORTHWARD...WITH ADDITIONAL MID-LEVEL JUICE MOVING IN FROM SE AZ COMPLIMENTS OF OLD/ONGOING SHOWERS AND STORMS. HURRICANE HILARY CHURNING TOWARD COLDER WATERS OVER THE PACIFIC... HOWEVER THE BRUNT OF THIS MOISTURE WILL BE SHIFTED IN THE OPPOSITE DIRECTION OF THE MAINLAND DUE TO ELY FLOW BENEATH UPPER LEVEL HIGH. MORNING CLOUDS WERE THIN ENOUGH FOR MANY AREAS WITHIN THE FORECAST AREA TO REALIZE CONVECTIVE TEMP...WHICH WAS AROUND 87F ON THE KABQ MORNING SOUNDING. DEVELOPING STORMS HAVE PLENTY OF MID-LEVEL ASCENT TO WORK WITH AS RUC80 ANALYSIS INDICATING VORTICITY MAXIMUM PUSHING THROUGH THE WRN PARTS OF THE STATE. EVEN STRONGER DISTURBANCES ARE SWINGING THROUGH THE BASE OF THE WEAK TROUGH OVER SRN CA/FAR NW OLD MEXICO...AND ARE PROGGED TO TRAVERSE THROUGH NEW MEXICO IN SEVERAL PIECES THIS EVENING/OVERNIGHT AND LIKELY INTO WED AS WELL. ATTM... IT APPEARS THE WEAK TROUGH AXIS WILL SWING THROUGH THE FOUR CORNERS REGION BY 06Z...THE NORTH CENTRAL MOUNTAINS BY 12Z AND THE NE ZONES BY 18Z. IN THE WAKE...EXPECT SUBSIDENCE AND DRIER WESTERLY FLOW TO PRECLUDE FURTHER PRECIPITATION. WITH ALL OF THIS IN MIND...HAVE HIT THE HARDEST POPS STRETCHING FROM THE SW CORNER OF THE CWA TO THE NE ZONES. SEVERE THREAT APPEARS TO BE MINIMAL AT THIS TIME. HOWEVER... A FEW STORMS MAY BE STRONG DURING PEAK HEATING HOURS COMPLIMENTS OF REASONABLE 25-35KT 0-6KM BULK SHEAR VALUES...HIGHEST ALONG THE WEST CENTRAL ARIZONA BORDER AND THE FAR NE CORNER OF NEW MEXICO. SHORT TERM MODELS ARE MORE INLINE WITH MOISTURE FIELDS FOR THE WED PERIOD. EXPECT DRIER 500MB AIR TO SHIFT INTO THE NW QUADRANT OF THE STATE...HOWEVER FEEL THAT ENOUGH LINGERING LOW-LEVEL MOISTURE COULD SPARK AN ISOLATED STORM. BULK OF THE 500MB JUICE WILL BE POSITIONED OVER THE SRN HALF OF NEW MEXICO AND THE ERN PLAINS. REMAINING WEAK DISTURBANCES WILL TRY TO RIP THROUGH SOUTHWESTERLY FLOW ON BACKSIDE OF STRENGTHENING HIGH. WILL STRUCTURE POP GRIDS WITH HIGHEST VALUES ACROSS THE SOUTH AND ISOLD COVERAGE IN THE NRN MOUNTAINS WHERE LESS MID-LEVEL MOISTURE SHOULD BE PRESENT. HIGH PRESSURE ALOFT BUILDS OVER THE RED RIVER VALLEY OF NRN TEXAS... WHICH SHOULD ALLOW MOST OF THE REGION TO ENTER RECYCLE MODE ON THU. WILL KEEP ISOLD POPS OVER MOST LOCATIONS...HOWEVER BOTH THE NAM/GFS ARE INDICATING A WEAK SHORTWAVE CLIPPING THE NE CORNER OF THE STATE AS IT RIDES THE NRN PERIPHERY OF UPPER HIGH. LATER SHIFTS WILL NEED TO MONITOR THIS FEATURE...HOWEVER IT COULD BE WORKING WITH LIMITED MID-LEVEL MOISTURE. ADDITIONALLY...POPS ACROSS THE WRN ZONES MAY BE OVERDONE AS WELL AS GFS IS MUCH MORE BULLISH WITH DRY AIR INTRUSION WITHIN THE DESERT SW. EXTENDED FORECAST REMAINS UNCHANGED AS INHERITED ISOLD POPS SPLIT THE DIFFERENCE WITH WET DGEX/DRY GFSLR. MODELS HAVING A DIFFICULT TIME ASCERTAINING THE STRENGTH AND POSITION OF THE 500MB HIGH. THE MAIN QUESTION WILL BE HOW FAR SOUTH THE WESTERLIES WILL TRAVEL IN RESPONSE TO A HIGH AMPLITUDE TROUGH MOVING INTO THE PACIFIC NW/NRN GREAT BASIN. DPORTER && .PRELIMINARY POINT TEMPS/POPS... FARMINGTON...................... 57 89 57 89 / 10 10 10 10 GALLUP.......................... 52 83 52 85 / 20 10 10 10 GRANTS.......................... 51 83 52 85 / 30 20 20 20 GLENWOOD........................ 57 88 57 89 / 30 20 20 20 CHAMA........................... 42 76 42 76 / 20 10 10 20 LOS ALAMOS...................... 51 83 51 83 / 30 10 10 10 RED RIVER....................... 39 73 39 75 / 30 10 10 20 TAOS............................ 48 82 49 84 / 20 10 10 20 SANTA FE........................ 52 82 53 84 / 30 10 20 10 SANTA FE AIRPORT................ 55 84 56 87 / 30 10 20 10 ESPANOLA........................ 53 86 54 89 / 20 10 10 10 ALBUQUERQUE HEIGHTS............. 64 86 65 89 / 30 10 20 10 ALBUQUERQUE VALLEY.............. 60 87 61 90 / 30 10 20 10 ALBUQUERQUE FOOTHILLS........... 61 85 62 88 / 30 10 20 10 ALBUQUERQUE WEST MESA........... 62 87 63 90 / 30 10 20 10 SOCORRO......................... 62 87 63 89 / 30 10 20 10 SANDIA PARK/CEDAR CREST......... 54 80 54 81 / 40 20 20 20 MORIARTY/ESTANCIA............... 52 84 52 85 / 40 20 20 10 CARRIZOZO....................... 60 85 61 86 / 30 20 20 10 RUIDOSO......................... 54 78 55 78 / 40 20 20 20 RATON........................... 51 83 51 88 / 30 10 10 10 LAS VEGAS....................... 52 81 53 84 / 40 10 10 10 ROY............................. 58 84 58 86 / 40 20 20 10 CLAYTON......................... 62 87 62 89 / 40 20 20 10 SANTA ROSA...................... 61 90 61 91 / 30 20 20 10 TUCUMCARI....................... 66 93 66 93 / 30 20 20 10 FORT SUMNER..................... 64 91 65 92 / 30 20 20 10 CLOVIS.......................... 65 91 65 92 / 20 20 20 10 PORTALES........................ 65 92 64 92 / 20 20 20 10 ROSWELL......................... 67 95 68 94 / 30 20 20 10 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 46 nm AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 243 PM EDT TUE AUG 23 2005 .SHORT TERM (TONIGHT THROUGH THURSDAY)... H5 SHORTWAVE RIDGING AND CLOUDINESS HAVE HELPED LIMIT INSTABILITY THIS AFTERNOON. SHOWERS ASSOCIATED WITH THE DIFFUSE EAST-WEST BOUNDARY AND HEATING HAVE BEEN ISOLATED EARLY THIS AFTERNOON. THE SHORTWAVE TROUGH SHOWN BY THE RUC THAT APPEAR TO BE SUPPORTING SHOWERS IN NORTH GEORGIA MAY CAUSE AN INCREASE IN COVERAGE IN THE FORECAST AREA LATE THIS AFTERNOON AND EVENING. BELIEVE INSTABILITY WILL MAINLY REMAIN WEAK BECAUSE OF THE LIMITED HEATING TODAY SO THE THREAT OF DAMAGING WINDS APPEARS SMALL. PRECIPITABLE WATER NEAR 2 INCHES... MAINLY IN THE SOUTH PART...AND POSSIBLE TRAINING ALONG THE EAST-WEST BOUNDARY SUPPORTS A THREAT OF VERY HEAVY RAIN. THE BOUNDARY SHOULD REMAIN IN THE FORECAST AREA WEDNESDAY AND SUPPORT ADDITIONAL SHOWERS AND THUNDERSTORMS. BOTH THE NAM AND GFS SHOW DEEPER MOISTURE SHIFTING SOUTH OF THE FORECAST AREA SO THE GUIDANCE CHANCE POPS APPEAR REASONABLE. BOTH MODELS SHOW FURTHER DRYING FOR WEDNESDAY NIGHT AND THURSDAY WITH RIDGING WEDGING INTO THE REGION FROM THE NORTH. THE NAM AND GFS SHOW LITTLE OR NO ISENTROPIC LIFT SO THE CHANCE OF RAIN APPEARS VERY LOW. && .LONG TERM (THURSDAY NIGHT THROUGH TUESDAY)... THE MAIN CONCERN DURING THE EXTENDED PERIOD IS POSSIBLE TROPICAL DEVELOPMENT OFF THE SOUTHEAST COAST. THE LATEST GFS SHOWS A STRONGER SYSTEM...BUT KEEPS THE LOW WELL EAST OF THE FORECAST AREA THROUGH THE PERIOD. PLAN TO KEEP POPS LOW THROUGH THE PERIOD WHICH AGREES WITH THE GFS ENSEMBLE MEAN POPS. ALSO PLAN TO USE THE ENSEMBLE MEAN TEMPERATURES WHICH ARE CLOSE TO CLIMATOLOGY. && .AVIATION... SCT TO BKN CUMULUS THIS AFTERNOON WITH EXTENSIVE MID LEVEL DECK. SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EARLY EVENING WITH MVFR CONDITIONS. PATCHY FOG DEVELOPING TOWARD 12Z...WITH IFR EXPECTED AGS AREA...OTHERWISE MVFR. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$ 05/05/19 sc AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 200 PM MDT TUE AUG 23 2005 .DISCUSSION...WATER VAPOR IMAGERY SHOWING STRONG LONGWAVE TROUGH OVER PACIFIC NORTHWEST WITH A SERIES OF SHORTWAVES MOVING IN THE SOUTHWEST FLOW AHEAD OF THE TROUGH. THE SHORTWAVES WERE LOCATED OVER WYOMING EXTENDING BACK INTO EASTERN IDAHO. THIS PLACES THE TRACK OF THE SHORTWAVE MAINLY ACROSS THE NORTHERN PORTIONS OF THE CWA THIS AFTERNOON AND EVENING. HOWEVER BEST INSTABILITY/SHEAR APPEARS TO BE CONCENTRATED MOSTLY IN THE SOUTHERN PORTIONS OF THE CWA AND BLACK HILLS. SURFACE ANALYSIS CONTINUES TO SHOW A RELATIVELY STATIONARY CONVERGENCE BOUNDARY OVER FAR NORTHEAST WYOMING WHERE SHOWERS AND THUNDERSTORMS HAVE BEEN REDEVELOPING ALL DAY LONG. MORE THUNDERSTORMS WILL DEVELOP THIS EVENING AS THAT BOUNDARY CONTINUES TO SLOWLY SLIDE EAST AND BEGINS INTERACTING WITH THE BLACK HILLS. STORMS WILL ALSO FORM SOUTH OF THE HILLS WHERE THE BEST CAPE LIES AND WHERE SPC HAS NUDGED THE SLIGHT RISK AREA EARLIER TODAY. HODOGRAPH FORECASTS STILL SHOW A POTENTIAL FOR SOME LOCALLY HEAVY RAINFALL RESULTING FROM THE SLOW/STATIONARY MOVEMENT EXPECTED FROM RIGHT MOVING SUPERCELLS. LATEST RUC SHOWING SOME STRONG CAPPING EAST OF THE HILLS...WITH SOME REINFORCING OF THE CAP LATE THIS EVENING. IT WILL BE INTERESTING TO SEE IF STORMS CAN DEVELOP/SUSTAIN THEMSELVES IN THAT AREA. MORE PRECIP EXPECTED TOMORROW WITH THIS ACTIVE WEATHER PATTERN. CUT OFF LOW WILL CONTINUE TO STRENGTHEN TONIGHT THROUGH MUCH OF THE DAY TOMORROW AS IT CONTINUES ITS SLOW PROGRESSION EASTWARD ACROSS THE NORTHERN MONTANA/CANADIAN BORDER. UPPER LEVEL DIFFLUENCE AHEAD OF THE CUT OFF LOW ALONG WITH WARM TEMPERATURES RIDING UP NORTH AHEAD OF A STRONG COLD FRONT WILL RESULT IN ANOTHER CHANCE FOR SHOWERS AND THUNDERSTORMS. BEST CAPE WILL BE IN THIS NOSE OF HIGHER THETA E ACROSS OUR NORTHERN AND NORTHEASTERN COUNTIES PRIOR TO FRONTAL PASSAGE. FRONT WILL SLIDE THROUGH THE CWA BEGINNING FROM THE NORTHWEST AROUND MID MORNING. STORMS WILL FIRE ALONG THE FRONT TOMORROW AFTERNOON...AND PUSH SOUTHEAST WITH IT THURSDAY EVENING...MAKING IT TO THE SE EDGES OF THE CWA BY OVERNIGHT WEDNESDAY. SOME LINGERING SHOWERS POSSIBLE ACROSS THE FAR SOUTHEASTERN ZONES THURSDAY AS THE FRONTAL BOUNDARY ALOFT CLEARS THE AREA. TEMPS WILL BE COOLER WITH MOST AREAS SEEING HIGHS IN THE 70S...AND UPPER 60S IN THE BLACK HILLS. STRONG SUBSIDENCE BEHIND THE DEPARTING TROUGH WILL DRY CONDITIONS OUT FOR FRIDAY WITH TEMPERATURES RECOVERING A LITTLE WITH HIGHS IN THE LOWER 80S. EXTENDED...WEAK RIDGING GIVES WAY TO ZONAL FLOW FOR SATURDAY THROUGH MONDAY AS FLAT UPPER RIDGE DOMINATES THE WEATHER. NEAR NORMAL TEMPS AND DRY WEATHER EXPECTED FOR THE WEEKEND. FLOW WILL TURN MORE SOUTHWESTERLY BY MONDAY NIGHT AS STRONG UPPER TROUGH BEGINS TO DIG OVER THE NORTHWEST AND NORTHERN ROCKIES. A CHANCE OF SHOWERS AND THUNDERSTORMS WILL RETURN TO THE AREA ON TUESDAY. && .AVIATION...GENERALLY...VFR CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THE FORECAST PERIOD WITH THE EXCEPTION OF MVFR OR LOWER CEILINGS AND VISIBILITIES NEAR THUNDERSTORMS. && .UNR...WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. && $$ sd