AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE UPTON NY 358 PM EDT MON MAY 28 2007 .SYNOPSIS... A COLD FRONT WILL SLIDE SOUTHEAST THROUGH THE TRI-STATE BY MID EVENING. HIGH PRESSURE THEN BUILDS IN FROM THE GREAT LAKES THROUGH TUESDAY EVENING...THEN MOVES TO THE WATERS OFF THE MID ATLANTIC COAST WEDNESDAY. A BACKDOOR COLD FRONT WILL APPROACH FROM THE NORTH WEDNESDAY NIGHT...AND PUSH THROUGH THE REGION THURSDAY. THE FRONT WILL STALL OUT TO OUR SOUTH THURSDAY NIGHT...THEN LIFT BACK NORTH THROUGH THE TRI-STATE AS A WARM FRONT ON FRIDAY. THE FRONT WILL THEN STALL OUT TO THE NORTH AND EAST OF THE AREA...AS HIGH PRESSURE REMAINS OFF THE SOUTHEAST COAST FRIDAY NIGHT THROUGH SUNDAY. A COLD FRONT WILL SLOWLY PUSH THROUGH THE TRI- STATE FROM THE WEST SUNDAY NIGHT AND MONDAY. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... OTHER THAN A TRACE FROM SPRINKLES THIS MORNING...THE COLD FRONT THAT CURRENTLY STRETCHES FROM N CENTRAL CT TO ROCKLAND COUNTY...BACK INTO CENTRAL PA AT 19Z...WILL PASS THROUGH THE REGION DRY BY MID EVENING. 18Z RUC SHOWS THETA-E RIDGE RETREATING RAPIDLY TO THE SW AHEAD OF THE FRONT...AS DRY AIR WORKS ITS WAY DOWN FROM ALOFT AS THE 850 COLD FRONT WAS ALREADY S OF LONG ISLAND BY 18Z...ALSO EFFECTIVELY MINIMIZE THE EXTENT OF ANY LIFT GENERATED BY THE SURFACE FRONT TO AROUND 5000 FT...NOT SUFFICIENT TO SUPPORT ANY MEANINGFUL CONVECTION. WHILE A STRAY SPRINKLE WITH ITS PASSAGE CANNOT COMPLETELY BE RULED OUT...THE PROBABILITY OF A SPRINKLE AT ANY ONE PLACE IS AT BEST 10 PCT...AND THE CHANCE OF MEASURABLE PRECIPITATION EVEN LESS THAN THAT. SKY CONDITIONS SHOULD IMPROVE FAIRLY RAPIDLY AFTER FRONTAL PASSAGE. WITH CLEAR SKY CONDITIONS BY AROUND MIDNIGHT (AT THE LATEST) AND LIGHT WINDS AFTER MIDNIGHT...WILL END UP WITH GOOD RADIATIONAL COOLING FOR THE LATTER 1/2 OF THE NIGHT...ALLOWING FOR LOWS TO FALL TO NEAR TO SLIGHTLY ABOVE NORMAL READINGS (EXCEPT IN THE NYC HEAT ISLAND WHERE LOWS WILL STILL BE 4-5 DEGREES ABOVE NORMAL)...AND FOR DEWPOINTS TO FALL INTO THE 40S...MAKING TONIGHT MUCH LESS HUMID THAN LAST NIGHT. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/... NAM AND GFS ARE FAIRLY SIMILAR IN THE SHORT TERM...FOLLOWED A BLEND THROUGH WEDNESDAY EVENING...THEN FOLLOWED THE NAM WITH THE BACKDOOR FRONT (NAM HISTORICALLY HANDLES BACK DOOR FRONTS BETTER THAN THE GFS). RIDGING BUILDS IN AT THE SURFACE AND ALOFT THROUGH WEDNESDAY MORNING...THEN ALL RIDGE AXES MOVE OFFSHORE BY WEDNESDAY EVENING. THIS ALLOWS FOR CONFLUENT FLOW TO SET UP OVER THE NORTHERN NEW ENGLAND/SOUTHERN CANADA IN THE MID TO UPPER LEVELS...SUPPORTING THE BUILDING OF HIGH PRESSURE INTO THAT REGION THURSDAY...PUSHING A BACK DOOR COLD FRONT THROUGH US TO OUR SOUTH AND WEST BY THURSDAY EVENING. THE RESULT WILL BE DRY CONDITIONS THROUGH WEDNESDAY NIGHT WITH HIGH TEMPERATURES INCREASING FROM AROUND 5 DEGREES ABOVE NORMAL ON TUESDAY TO AROUND 10 DEGREES ABOVE NORMAL WEDNESDAY (AWAY FROM THE COAST/LONG ISLAND WHERE A SEA BREEZE WILL LIMIT HIGHS ON WEDNESDAY TO NEAR TUESDAYS LEVELS). LOWS WILL GENERALLY RUN 2-5 DEGREES ABOVE NORMAL TUESDAY AND WEDNESDAY NIGHT. TEMPERATURES ON THURSDAY ARE TRICKY...TOTALLY DEPENDANT ON THE TIMING OF THE PASSAGE OF THE BACK DOOR FRONT. IF IT DOES NOT PUSH THROUGH UNTIL MID TO LATE AFTERNOON...INLAND/NYC HEAT ISLAND LOCATIONS COULD SEE HIGHS WELL INTO THE 80S...WITH COASTAL/LONG ISLAND LOCATIONS GENERALLY 75 TO 80. IF THE FRONT PUSHES THROUGH DURING THE MORNING...COASTAL/LONG ISLAND LOCATIONS WILL STRUGGLE TO GET OUT OF THE MID 60S (WATER TEMPERATURES RUNNING MID 50S TO LOWER 60S)...WHILE INLAND LOCATIONS WON/T GET MUCH PAST THE MID 70S. FOR NOW HAVE PLAYED SOMEWHERE BETWEEN THE TWO EXTREMES WITH AREAS N/W OF NYC GETTING INTO THE LOWER 80S...METRO NYC/INTERIOR PORTIONS OF THE WESTERN 1/2 OF OUR CWA GETTING TO AROUND 80...MOST OF WESTERN/CENTRAL LONG ISLAND AND COASTAL WESTERN AND INTERIOR EASTERN CT GETTING TO THE MID 70S...AND EASTERN CT/LONG ISLAND GETTING TO 65-70. HAVE PLACED SLIGHT CHANCE POPS NE PORTIONS THU MORNING FOR SHOWERS...THEN CHC POPS ALL BUT FAR SW THU AFTERNOON FOR SHRA/TSRA. CLOUD COVER SHOULD RAPIDLY INCREASE AND TEMPERATURES FAIRLY RAPIDLY FALL BEHIND THE FRONT...ESPECIALLY WITH AN AFTERNOON FRONTAL PASSAGE. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... BACK DOOR FRONT STALLS OUT TO OUR SOUTH THURSDAY NIGHT (LIKELY WITH LOW CLOUDS AND LIGHT RAIN/DRIZZLE) THEN LIFTS TO THE NORTH BY FRIDAY AFTERNOON (FOR NOW USED GFS TIMING TO CLEAR FRONT TO THE NORTH). QUITE A BIT OF UNCERTAINTY IN THE EXTENDED WITH NO REAL CLEAR SIGNAL FROM ANY ONE MODEL OR ENSEMBLE OF MODELS. FOR NOW IT APPEARS THE BACKDOOR FRONT WILL STALL OUT TO THE NORTH AND EAST FRIDAY NIGHT INTO SUNDAY...THOUGH THERE IS SOME INDICATIONS THE FRONT COULD SINK BACK TO OUR SOUTH COME LATE SATURDAY. ANOTHER UNCERTAINTY IS HOW QUICKLY THE MIDWEST CUTOFF MOVES EASTWARD...BRINGING ITS COLD FRONT EASTWARD WITH IT...AND FINALLY THE EVOLUTION OF ANY TROPICAL MOISTURE/SYSTEM FOR SATURDAY/SUNDAY. FOR NOW HAVE LEANED TOWARDS THE 0Z GFS ENSEMBLE MEAN...WHICH KEEPS THE BACK DOOR FRONT TO THE NORTH AND BRINGS THE COLD FRONT THROUGH SUNDAY NIGHT/MONDAY...AND DOES NOT REFLECT ANY DEVELOPMENT IN THE GULF (NO CLEAR SIGNAL FROM ALL ITS MEMBERS). && .AVIATION /19Z MONDAY THROUGH SATURDAY/... VFR. COULD SEE AN ISOLATED SHOWER AHEAD OF APPROACHING COLD FRONT BEFORE 00Z...ONLY WORTH MENTION OF TEMPO BROKEN VFR CIGS ATTM. WINDS HAVE SHIFTED W-NW 10-15 KT AT KHPN/KSWF...BUT ARE STILL VARYING ROUGHLY BETWEEN 240-290 AT KTEB/KEWR...WITH OCCASIONAL GUSTS A LITTLE OVER 15 KT. THIS MAY CONTINUE TO BE THE CASE FOR AT LEAST A COUPLE MORE HOURS UNTIL THE FRONT GETS CLOSER TO THE TERMINALS. SEA BREEZE REGIME IS IN PLACE AT COASTAL TERMINALS...INCLUDING KLGA WHICH WAS JUST ON THE EDGE PER JFK TERMINAL DOPPLER RADAR...WITH SW FLOW 10-15 KT. WINDS AT ALL TERMINALS SHOULD SHIFT NW THIS EVENING WITH COLD FROPA...ABOUT 23Z AT COASTAL CT TERMINALS AND 00Z NYC AREA AND KISP. SKIES THEN QUICKLY CLEAR THIS EVENING...WITH LIGHT NORTHERLY FLOW INTO TUE MORNING. SEA BREEZES SHOULD REDEVELOP AT COASTAL TERMINALS BY 15Z-16Z. OUTLOOK FROM 18Z TUE THROUGH SAT...VFR THU MORNING. SCATTERED CONVECTION COULD BRING BRIEF SUB-VFR CONDITIONS THU AFTERNOON/EVENING. MORE WIDESPREAD SUB-IFR CONDITIONS ARE POSSIBLE THU NIGHT AND FRI MORNING...WITH LOW STRATUS OVERSPREADING THE AREA FROM THE EAST AFTER BACK DOOR COLD FROPA. WIDELY SCATTERED DIURNAL CONVECTION WITH BRIEF SUB-VFR CONDITIONS IS AGAIN POSSIBLE BOTH FRI/SAT AFTERNOON/EVENING. && .MARINE... A COLD FRONT WILL MOVE THROUGH THE AREA WATERS THIS EVENING WITH WINDS GENERALLY SW TO W EARLY ON BECOMING NW TO N BY LATE TONIGHT. SEAS OF 2 TO 3 FT WILL CONTINUE THROUGH TONIGHT ON THE OCEAN WATERS. HIGH PRESSURE BUILDS INTO THE REGION TUESDAY AND WEDNESDAY WITH TRANQUIL CONDITIONS. A BACK DOOR COLD FRONT WILL DROP IN FROM THE NORTH ON THURSDAY...SHIFTING WINDS FROM SW TO SE...HOWEVER SUB SCA CONDITIONS WILL PERSIST. WEAK WAVES OF LOW PRESSURE WILL THEN DOMINATE THE WEATHER PATTERN TOWARD THE END OF THE WEEK. && .HYDROLOGY... NO WIDESPREAD SIGNIFICANT PRECIPITATION (0.5 INCHES OR MORE) IS EXPECTED ACROSS THE REGION THROUGH THE WEEK. AS A RESULT LEVELS ON AREA RIVERS AND STREAMS WILL REMAIN NEARLY STEADY OR SLOWLY FALL. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ PUBLIC/HYDROLOGY...MALOIT AVIATION...BG MARINE...JC ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 400 AM EDT MON MAY 28 2007 .SYNOPSIS... A COLD FRONT WILL BEGIN TO WORK ACROSS OUR REGION THIS MORNING...BUT NOT COMPLETELY CLEAR OUR SOUTHEASTERN ZONES UNTIL SOMETIME DURING THE AFTERNOON. TO THE SOUTH AND EAST OF ALBANY THE AIR WILL REMAIN JUST UNSTABLE ENOUGH TO A STRAY SHOWER OR POPUP THUNDERSTORM BUT OVERALL...THE VAST MAJORITY OF THE REGION WILL ENJOY A COMPLETELY DRY MEMORIAL DAY WITH SEASONABLY WARM TEMPERATURES. HIGH PRESSURE...FORMING OVER THE GREAT LAKES TONIGHT...WILL BUILD INTO OUR REGION ON TUESDAY INTO WEDNESDAY. && .NEAR TERM /UNTIL 11 AM THIS MORNING/... WE STILL SEE A FEW ISOLATED "PINHEAD" SHOWERS LINGERING ON OUR RADAR...MAINLY TO OUR SOUTH AND WEST. THE COLD FRONT ALSO SHOWS UP AS A "FINE" LINE...WORKING JUST TO THE LAKE OF ONTARIO...MOVING ABOUT 40 MPH. SUSPECT THIS FRONT WILL SLOW DOWN A BIT AS IT RUNS INTO THE RESISTANCE FROM HIGH PRESSURE ALOFT...BUT EVEN SO...SHOULD STILL COMPLETELY CLEAR OUR CWA BY LATE AFTERNOON. IFR SATELLITE IMAGES INDICATE AN OVERALL "WARMING" OF CLOUD TOPS...A SIGNATURE OF WEAKENING FORCING. ACCORDING TO THE LATEST RUC INFORMATION...SBCAPES START OFF IN THE POSITIVE MODE ACROSS THE ENTIRE EARLY...AND ACCORDING TO MODEL SOUNDINGS...COULD JUMP AS HIGH AS ABOUT 1000 J/KG LOCALLY...ALTHOUGH VALUES ARE LOWER IN THE BUFKIT. ONE PROBLEM EARLY WILL BE PATCHY FOG...FOUND IN THOSE SHELTERED VALLEYS WHERE THE CLOUDS HAVE THINNED AND THE GROUND IS WET FROM THE EARLIER RAINS. WILL THROW IN SOME PATCHY DENSE FOG EARLY. && .SHORT TERM /11AM THIS MORNING THROUGH WEDNESDAY NIGHT/... BY MIDDAY...SBCAPES ARE PROJECTED DROP QUITE A BIT FROM ALBANY NORTH AND WESTWARD. TO THE SOUTHEAST...SBCAPES COULD REACH 1500-2000 J/KG UNTIL ABOUT 4 PM...WITH THE BUFKIT SHOWING VALUES UNDER 1000 J/KG. WHILE FORCING IS WEAK...WITH THE SHORT WAVE DRIVING THE COLD FRONT...LIFTING NORTHEAST...WE FELL THERE COULD JUST BE ENOUGH INSTABILITY...WHEN COMBINED WITH ANY UPSLOPE COMPONENT TO TRIGGER A RANDOM SHOWER OR STORM. THEREFORE...HAVE PLACED SLIGHT CHANCES INTO THESE AREAS FOR THE REMAINDER OF THE DAY. PLUGGING IN VALUES OFF THE BUFKIT SOUNDING FROM KPOU INTO THE MAGLENTA EQUATION... SBCAPES = 600 J/KG MAX SOUNDING WIND = 80 KTS EHI = -.25 SRH = 21 GIVE US A VALUE OF 3.3 WHICH IS CONSIDERED IN THE MINOR EVENT RANGE SHOULD CONVECTION DEVELOP. HOWEVER...THE OVERALL WIND FIELD IS NOT REALLY FAVORABLE FOR ANY SEVERE DEVELOPMENT...AS THE NOSE OF THE H850 (ONLY ABOUT 30 KTS) DOES NOT LINE UP WITH ANY DIVERGENCE ALOFT AS THE LF QUAD OF THE UPPER JET REMAINS WELL NORTH. THERE IS ONLY VERY LIMITED SPEED SHEAR IN THE COLUMN. EITHER WAY...THE THREAT FROM SEVERE IS WAY TOO LOW TO INCLUDE IN OUTLOOK. ONE THING OF NOTE IS THAT THE WET-BULB ZERO LOOKS TO FALL TO ABOUT 8KFT AS THE DAY PROGRESSES. THIS VALUE IS A BIT LOW FOR FOR THE FORMATION OF LARGE HAIL STONES...BUT COULD REAP SMALL ONES. HOWEVER...AGAIN SINCE THE THREAT OF STORMS IS SO LOW TO BEGIN WITH...AT THIS POINT FEEL NO NEED TO PLACE ANY MENTION OF ENHANCED WORDING OF ANY KIND IN ANY OF THE SOUTHEASTERN ZONES. BY TONIGHT...DRIER AND SLIGHTLY COOLER AIR WILL HAVE INFILTRATED THE SCENE AS THE AFOREMENTIONED HIGH PRESSURE BEGINS BUILDING IN. THE SKY WILL CLEAR AND FINE LATE SPRING WEATHER WILL SETTLE INTO THE AREA INTO WEDNESDAY. ONLY CHANGES TO THIS PERIOD COMPARED TO LAST...WAS TO LOWER CLOUDS TO THE CLEAR THRESHOLD MUCH OF THE TIME. WENT CLOSE TO MAV GUIDANCE THROUGH THE PERIOD...SEEING NO REASON TO SIGNIFICANTLY STRAY FROM VALUES. && .LONG TERM /THURSDAY THROUGH SUNDAY/... HERE ARE BIG DIFFERENCES IN THE DETAILS WITH THE MODELS AS WE HEAD INTO THE LATTER PART OF THE WEEK INTO NEXT WEEKEND...BUT THE OVERALL AGREEMENT IS FOR UNSETTLED WEATHER WITH BELOW NORMAL TEMPERATURES. STRONG RIDGING WILL DEVELOP ALONG THE WEST COAST BY MID WEEK WITH A TROUGH DIGGING ACROSS THE PLAINS AND HEADING EASTWARD. THE EASTERN UNITED STATES WILL BE UNDER THE INFLUENCE OF A DEEP MID LEVEL TROUGH AND POSSIBLY EVEN A CUT-OFF LOW. && .AVIATION /07Z MONDAY THROUGH FRIDAY/... COLD FRONT WAS SLICING ACROSS CENTRAL NEW YORK AND PROGRESSING EAST BETWEEN 30-35 KTS. WHILE MOST OF THE INSTABILITY HAS DIMINISHED AND IS WELL EAST OF THE CWA...STILL THE POTENTIAL FOR SOME SHOWERS TO DEVELOP UNTIL FROPA THE NEXT SEVERAL HOURS. SO THIS WILL KEEP THE MVFR CEILINGS WITH THE POTENTIAL FOR IFR CIGS/VIS WITH A RELATIVELY LIGHT FLOW AHEAD OF THE FROPA. FOR MON...EXPECT LINGERING AREAS OF MVFR VSBYS/CIGS FIRST THING IN THE MORNING...ALONG WITH POSSIBLE ISOLATED IFR...ESP AT KGFL.... EXPECT CONDITIONS TO IMPROVE TO VFR BY 13Z-15Z/MON. FRONT MIGHT BE A LITTLE CLOSER TO KPOU WHERE A SLIGHT CHANCE FOR CONVECTION WILL EXIST FOR TODAY. HOWEVER...WILL REFRAIN FROM MENTIONING IN THE TAF TODAY. WINDS BY MID MORNING MONDAY...WITH SUSTAINED SPEEDS OF 10-15 KT...AND POSSIBLE GUSTS UP TO 20-25 KT BY AFTERNOON...ESPECIALLY AT KALB WHERE FUNNELING OF WIND DOWN THE MOHAWK VALLEY SHOULD OCCUR. TUESDAY AND WEDNESDAY...VFR NO SIG WX. THURSDAY AND FRIDAY...VFR WITH MVFR POSSIBLE WITH THE CHANCE FOR SCATTERED CONVECTION. && .FIRE WEATHER... PARTLY SUNNY...COOLER...AND EVENTUALLY DRIER MEMORIAL DAY WITH THE MIDDAY HUMIDITY RANGING FROM 30 TO 40 PERCENT AND WINDS FROM THE WEST 10 TO 20 MILES PER HOUR...SOME GUSTS APPROACHING 25 MPH. TONIGHT AND TUESDAY RELATIVE HUMIDITIES AGAIN WILL BE 75-95 PERCENT AT NIGHT AND AROUND 30 TO 40 PERCENT DURING THE DAY ON TUESDAY. THE WIND WILL BE WEST TO NORTHWEST AT 10 TO 20 MPH DURING THE DAY AND LIGHT AND VARIABLE AT NIGHT. LOOKING AHEAD INTO WEDNESDAY...DRY WEATHER SHOULD PREVAIL WITH HIGH PRESSURE REMAINING IN CONTROL. THIS SHOULD PROVIDE LIGHT WINDS WITH DAYTIME RH VALUES AROUND 30 PERCENT AND NIGHT READINGS WELL INTO THE 90 PERCENTILE. && .HYDROLOGY... RIVERS CONTINUE AT LOW FLOWS RESULTING FROM A PROLONGED PERIOD OF FAIRLY DRY WEATHER AND ABOVE NORMAL TEMPERATURES. SHOWERS AND THUNDERSTORMS THROUGH SUNDAY EVENING AVERAGED BETWEEN ONE QUARTER AND THREE QUARTERS OF AN INCH WITH NEGLIGIBLE IMPACTS TO THE RIVERS/STREAMS (THE HIGHER AMOUNTS EXTENDING FROM ALBANY INTO THE BERKSHIRES AND SOUTHERN VERMONT). DRY AIR WILL MOVE IN TODAY AND DOMINATE THE WEATHER THROUGH WEDNESDAY AFTER WHICH ANOTHER DISTURBANCE IS LIKELY TO BRING MORE SCATTERED SHOWERS AND THUNDERSTORMS. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...HWJIV NEAR TERM...HWJIV SHORT TERM...HWJIV LONG TERM...HWJIV AVIATION...BGM FIRE WEATHER...BGM HYDROLOGY...BGM ct AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE TALLAHASSEE FL 500 AM EDT MON MAY 28 2007 .SYNOPSIS... 07Z WATER VAPOR AND H4 RUC ANALYSIS CONTINUE TO SHOW UPPER RIDGING FROM THE EASTERN GULF OF MEXICO UP OVER THE SOUTHEASTERN STATES. THE NORTHERN STREAM FLOW IS RATHER ZONAL IN NATURE AT THIS TIME RUNNING ALONG THE NORTHER TIER OF STATES. TWO FAIRLY POTENT SHORTWAVES ARE SEEN EMBEDDED WITH THE FLOW OVER THE PACIFIC NORTHWEST AND ANOTHER EXITING THE GREAT LAKES TOWARD THE NORTHEAST U.S AND CANADIAN MARITIMES. FURTHER SOUTH IN THE UPSTREAM FLOW FROM OUR FORECAST AREA WE SEE A BROAD UPPER TROUGH ACROSS THE SOUTHERN PLAINS...THIS TROUGH WILL SLOWLY PUSH EAST THROUGH THE NEXT SEVERAL DAYS AND MAY FINALLY BRING THE CHANCE FOR SOME SCATTERED SHOWERS TO OUR DROUGHT STRICKEN REGION BY THE MID/LATE WEEK PERIOD. LITTLE CHANGE IS SEEN AT THE SURFACE WITH HIGH PRESSURE CONTINUING TO NOSE BACK OFF THE ATLANTIC INTO THE SOUTHEASTERN STATES. OUR FORECAST AREA REMAINS IN EASTERLY FLOW ON THE SOUTH SIDE OF THIS RIDGE. 28/00Z KTLH SOUNDING FROM LAST EVENING ONCE AGAIN SHOWED VERY IMPRESSIVE DIURNAL MIXING UP TO 8KFT+. THE SUPPRESSING EFFECTS OF THE UPPER RIDGE ARE ALSO STILL SEEN WITH A HEALTHY WARM LAYER CAP IN THE MID LEVELS AND NO LACK OF DRY AIR THROUGH ALMOST THE ENTIRE COLUMN. AREAS ACROSS SOUTHWEST AND SOUTH-CENTRAL GEORGIA ENDURED ANOTHER DAY OF SMOKE ON SUNDAY WITH THE PLUME MIGRATING WEST AND NORTHWEST WITH THE FLOW. GENERALLY THIS PLUME STAYED TO THE NORTH OF OUR FLORIDA ZONES YESTERDAY AND A SIMILAR SCENARIO IS ANTICIPATED ON MONDAY. && .SHORT TERM...TODAY THROUGH WED. ONE MORE DAY UNDER THE INFLUENCE OF THE UPPER RIDGE FOR THE FORECAST AREA. SURFACE RIDGING CENTERED OFF THE CAROLINA COAST WILL ALSO CONTINUE TO DOMINATE WITH REGION WITH A DRY EASTERLY FLOW. THE TIGHT GRADIENT ALONG THE SOUTH EDGE OF THIS RIDGE CURRENTLY WILL RELAX A BIT BY AFTERNOON WHICH SHOULD ALLOW HEALTHY SEA-BREEZE CIRCULATIONS TO DEVELOP. AREAS DOWNWIND OF THE GEORGIA WILDFIRES (MAINLY SOUTH-CENTRAL AND SOUTHWEST GEORGIA) SHOULD PREPARE FOR ANOTHER DAY OF SMOKE/HAZE WITH THE THICKEST SMOKE AND LOWEST VISIBILITIES STILL AROUND AND TO THE NORTH OF VALDOSTA IN CLOSEST PROXIMITY TO THE FIRES. TODAY SHOULD SEE THE BEGINNING OF THE RETURN OF SOME LOW LEVEL MOISTURE. THIS WILL ESPECIALLY BE TRUE IN THE WEST WITH AFTERNOON DEWPOINTS A BIT HIGHER THAN OVER THIS PAST WEEKEND MAKING IT FEEL MORE LIKE LATE MAY OUTSIDE. THE MID/UPPER LEVEL RIDGING WILL STILL HAVE ENOUGH INFLUENCE TO KEEP CONVECTION SUPPRESSED. CAN NOT RULE OUT AN ISOLATED SHOWER LATE THIS AFTERNOON ACROSS THE FLORIDA PANHANDLE ALONG THE SEA-BREEZE...HOWEVER FEEL ANY COVERAGE WILL BE VERY ISOLATED IN NATURE KEEPING POPS IN THE SILENT 5-10% RANGE. AS HAS BEEN THE SITUATION DURING THE PAST FEW DAYS WILL EXPECT A RATHER HEALTHY CU FIELD TO DEVELOP DURING THE AFTERNOON AND EARLY EVENING WITH SCT-BKN CLOUDS AROUND 6-7KFT. MIXING FORECAST SOUNDINGS DOWN FROM AROUND 7KFT THIS AFTERNOON GIVES AFTERNOON HIGH TEMPERATURES GENERALLY IN THE UPPER 80S ACROSS INLAND AREAS. CLOSER TO THE COAST WILL SEE TEMPS REACH THE MIDDLE 80S BEFORE SEA-BREEZE CIRCULATIONS DEVELOP IN THE EARLY AFTERNOON KEEPING TEMPERATURES IN CHECK. UPPER TROUGH MENTIONED ABOVE BEGINS TO SLIDE ALONG THE GULF COAST TONIGHT. GFS/NAM BOTH SHOWING WEAK SHORTWAVE ENERGY EMBEDDED WITHIN THE TROUGH OVER THE NORTH-CENTRAL GOMEX WITH SHOWER COVERAGE INCREASING TO OUR WEST. FEEL THAT THE MOISTURE SHOWN BY THE MODELS IS A BIT OVERDONE AND QUICK TO COME EAST...BUT WILL INTRODUCE A SLIGHT CHANCE POP OVER THE WESTERN COASTAL WATERS LATE TONIGHT AND TUESDAY MORNING. KEEPING POPS OFFSHORE FOR NOW...BUT WILL BE A CLOSE CALL FOR PLACES LIKE WALTON AND BAY COUNTIES AND POPS MAY NEED TO BE EXPANDED INTO THESE AREAS LATER TODAY. EITHER WAY MID/HIGH LEVEL CLOUDS WILL BE ON THE INCREASE FROM WEST TO EAST HELPING KEEP TEMPERATURES GENERALLY IN THE MIDDLE 60S ACROSS THE REGION. BROAD UPPER TROUGH CONTINUES TO SIT ACROSS THE WESTERN AND CENTRAL GULF COAST TUESDAY INTO WEDNESDAY. ALTHOUGH THE TROUGH AXIS DOES NOT MOVE MUCH...THE GFS SHOWS SEVERAL PIECES OF SHORTWAVE ENERGY EJECTING EASTWARD INTO OUR GENERAL VICINITY. THESE PIECES OF ENERGY ARE LIKELY OVERDONE. HOWEVER...THE SHEAR FACT THAT THE UPPER RIDGE IS CONTINUING TO BREAK DOWN AND LOW/MID LEVEL MOISTURE IS ON THE RISE AS THE SURFACE RIDGE RETREATS SLOWLY NORTHEAST IS ENOUGH TO FEEL CONFIDENT ABOUT RE-INTRODUCE POPS...MAINLY TO SOUTHERN AND WESTERN PORTIONS OF THE COUNTY WARNING AREA. WILL GENERALLY KEEP SLIGHT CHANCE TO LOW END CHANCE POPS (20-30%) BOTH DAYS WITH CONVECTION STILL WIDELY SCATTERED IN NATURE. BEST CHANCES AS MENTIONED ABOVE WILL BE ACROSS THE WESTERN HALF OF THE AREA... ESPECIALLY THE FLORIDA PANHANDLE...WHERE SEA-BREEZE CONVERGENCE WILL HAVE EVEN LESS SUPPRESSION FROM ABOVE. FURTHER NORTH AND EAST ACROSS A GOOD CHUNK OF OUR GEORGIA ZONES AND DOWN INTO PORTIONS OF THE EASTERN BIG BEND WILL KEEP POPS STILL IN THE SILENT 5-10% RANGE AS LOW LEVEL MOISTURE MAY BE BE LACKING AND THE UPPER RIDGE AXIS WILL STILL BE IN FAIRLY CLOSE PROXIMITY. .LONG TERM...THURSDAY THROUGH SUN. STILL SOME QUESTIONS IN REGARDS TO THE EXACT PATTERN EVOLUTION INTO THE LATER PART OF THE WORKWEEK AND NEXT WEEKEND...ESPECIALLY IN TERMS OF SURFACE PATTERN. BUT FIRST THINGS FIRST. THURSDAY WILL STILL SEE THE BROAD UPPER TROUGH AXIS TO OUR WEST BUT TRYING TO MAKE ITS WAY TOWARD THE CENTRAL GULF COAST. A MORE SOUTHEASTERLY FLOW WILL CONTINUE TO INCREASE MOISTURE TO THE REGION AND WITH THE HELP OF THE UPPER LEVEL DYNAMICS HAVE AT LEAST SLIGHT CHANCE POPS ALMOST REGIONWIDE FOR THURSDAY AFTERNOON. ONLY PLACE THAT STILL LOOKS UNLIKELY TO SEE ANY CONVECTION IS ACROSS SOUTH-CENTRAL GA WHERE MOISTURE MAY STILL BE LACKING. BY LATE FRIDAY THE UPPER PATTERN ACROSS THE CONUS IS BECOMING VERY AMPLIFIED FOR EARLY JUNE WITH A LARGE RIDGE ALONG THE WEST COAST AND A DEEPENING TROUGH ACROSS THE NATIONS MID-SECTION. THE PATTERN ONLY CONTINUES TO AMPLIFY THROUGH THE WEEKEND WITH A VERY DEEP TROUGH FROM THE GREAT LAKES TO THE SOUTHEASTERN STATES BY SUNDAY. LARGE SCALE CYCLONIC FLOW OVERHEAD WILL AID CONVECTION THROUGH THE WEEKEND AND HAVE WIDESPREAD CHANCE POPS FOR ALL ZONES SATURDAY INTO SUNDAY. TEMPERATURES WILL BE RATHER TRICKY THROUGH THE EXTENDED PERIOD. THE COLUMNS POTENTIAL WILL BE RATHER WARM BUT WITH THE UNSETTLED UPPER LEVELS THERE MAY BE TIMES OF SUBSTANTIAL CLOUD COVER. WITH THIS IN MIND RAN TEMPERATURES NEAR CLIMO. HOWEVER...TEMPERATURES SEVERAL DEGREES WARMER ARE CERTAINLY POSSIBLE ANY DAY IF SIGNIFICANT SUNSHINE OCCURS. WAS HOPING THAT THE GLOBAL MODELS WOULD COME INTO BETTER AGREEMENT WITH REGARDS TO A POSSIBLE SYSTEM COMING OUT OF THE WESTERN CARRIBEAN INTO THE EASTERN GOMEX DURING THE END OF THE WEEK AND FIRST HALF OF THE WEEKEND. UNFORTUNATELY THE GUIDANCE REMAINS SPLIT. THE GFS IS SHOWING A RATHER WEAK WAVE MOVING UP WITH JUST AN INCREASE IN LOW LEVEL MOISTURE WHILE THE ECMWF AND UKMET DEVELOP THE SYSTEM A BIT MORE BRINGING A CLOSED LOW INTO THE SOUTHEAST GULF ON SATURDAY...THEN CROSSING THE FLORIDA PENINSULA. THE CANADIAN WHICH HAS BEEN BULLISH WITH THIS SYSTEM ALL ALONG IS SHOWING THE CLOSED LOW MOVING NORTH THROUGH THE EASTERN GOMEX INTO OUR AREA. WITH AS MUCH UNCERTAINTY AS THERE IS AT THIS TIME...HAVE RAN THE FORECAST CLOSER TO THE GFS SOLUTION AS IS SUGGESTED BY HPC WHILE WAITING FOR BETTER MODEL AGREEMENT. ONE WAY OR THE OTHER IT APPEARS AS THOUGH THERE WILL FINALLY BE A CHANCE FOR SOME LOCALLY BENEFICIAL RAIN BY THE END OF THE WEEK. && .MARINE... COASTAL WATERS WILL REMAIN ON THE SOUTH SIDE OF SURFACE HIGH PRESSURE CENTERED NEAR THE CAROLINA COAST THROUGH MUCH OF THE FORECAST PERIOD. THIS WILL KEEP THE FLOW FROM THE EAST AND SOUTHEAST THROUGH AT LEAST MIDWEEK. EXPECT WINDS TO COME UP TO CAUTION LEVELS ESPECIALLY ACROSS THE OFFSHORE WATERS EACH NIGHT THROUGH MIDWEEK THEN DROP BELOW CAUTION EACH MORNING. AS AN UPPER LEVEL SYSTEM APPROACHES FROM THE WEST DURING THE FORECAST PERIOD THE CHANCE FOR SCATTERED SHOWERS AND THUNDERSTORMS WILL ALSO INCREASE ACROSS THE COASTAL WATERS. && .AVIATION... THE SMOKE PLUME HAS REMAINED NORTH OF THE FL/GA BORDER DURING PREDAWN HOURS. LAST FEW NIGHTS VERY PERSISTENT PATTERN AND SEE NO REASON TO DEVIATE FORM THIS PATTERN NEXT 24 HRS. THUS... LIGHT ESE FLOW UNTIL TILL 3-4AM WITH GREATEST IMPACT AT ABY WITH OCNL IFR VSBYS AND TO A LESSER EXTENT AT VLD AND DHN WITH MVFR VSBYS. THEN...WINDS BECOME NEAR CALM AND ABY IMPROVES TO MVFR AND VLD DETERIORATE TO IFR. BY MID MORNING...WINDS PICK UP AND ORIENT BACK TO W-E SO VLD REMAINS MOST PROBLEMATIC WITH MVFR VSBYS THRU DAYLIGHT HOURS. EXPECT FLA TAF SITES TO REMAIN SOUTH OF SMOKE. && .FIRE WEATHER... HIGH PRESSURE WILL CONTINUE TO PROVIDE A FAIRLY DRY EASTERLY FLOW FOR LATE MAY OVER THE NEXT DAY OR TWO. ALTHOUGH RH VALUES WILL BE RATHER LOW THIS AFTERNOON WITH MANY PLACES REACHING THE UPPER 30S...CRITICAL LEVELS ARE NOT ANTICIPATED. TEMPERATURES ARE FORECAST TO BE A COUPLE DEGREES WARMER ACROSS INLAND PORTIONS OF FLORIDA BIG BEND ON TUESDAY AND WITH SIMILAR AFTERNOON DEWPOINTS THE CURRENT GRIDS DO SHOW 1 TO 3 HOURS OF RH AROUND 35 PERCENT. THESE RH VALUES COMBINED WITH DISPERSION INDICES ABOVE 75 HAVE PROMPTED A FIRE WX WATCH TO BE ISSUED FOR INLAND PORTIONS OF THE EASTERN FLORIDA PANHANDLE. INCREASING LOW LEVEL MOISTURE MORE CLOUDCOVER SHOULD END ANY CRITICAL FIRE WX CONDITIONS BY WEDNESDAY INTO THURSDAY. && .HYDROLOGY...MODERATE DROUGHT CONDITIONS CONTINUE ACROSS THE WESTERN PANHANDLE AND SE AL, WITH SEVERE TO EXTREME DROUGHT ELSEWHERE ACROSS THE FORECAST AREA. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 87 65 89 64 89 / 05 05 10 10 20 PANAMA CITY 86 68 86 69 87 / 05 10 20 10 20 DOTHAN 87 65 88 65 88 / 05 05 20 10 20 ALBANY 87 64 89 64 89 / 0 0 10 10 10 VALDOSTA 86 63 88 62 88 / 0 0 10 10 10 CROSS CITY 88 64 91 63 91 / 05 05 10 10 20 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY EVENING FOR THE FOLLOWING ZONES: DIXIE...JEFFERSON... LAFAYETTE...LEON...MADISON...TAYLOR. GM...NONE. && $$ AVIATION...BLOCK REST OF DISCUSSION...MROCZKA fl AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PEACHTREE CITY GA 955 PM EDT TUE MAY 29 2007 .UPDATE... UPPER RIDGE CONTINUES TO DEFLECT MOISTURE IN THE WESTERLIES AWAY FROM GEORGIA. BASED ON SATELLITE IMAGERY...IT LOOKS LIKE BANDS OF HIGH CIRRUS WILL AFFECT NORTHERN AND WESTERN COUNTIES MORE THAN CENTRAL AND EAST OVERNIGHT. THIS SHOULD RESULT IN MOSTLY CLEAR SKIES ACROSS MUCH OF CENTRAL GEORGIA. OVERNIGHT MIN TEMPERATURES LOOK TO BE ON TRACK BASED ON RECENT TRENDS AND 00Z SOUNDING. THE SOUNDING AND VAD WINDS AT 00Z SHOW THE EAST TO SOUTHEAST FLOW PERSISTING. A SLIGHT INCREASE IN THE SOUTHERLY COMPONENT IS FORECAST BY THE RUC TOWARD MORNING. THIS SHOULD BRING AREAS OF SMOKE FARTHER NORTH WEDNESDAY...PROBABLY AFFECTING COLUMBUS ALONG WITH AMERICUS AND VIDALIA. && (PREVIOUS DISCUSSION...) .SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/... LARGE UPPER RIDGE CONTINUES ITS HOLD OVER THE SOUTHEAST. ENOUGH MOISTURE IS WORKING ITS WAY IN THE SOUTHEAST FLOW FROM THE ATLANTIC TO PROVIDE FOR SOME AFTERNOON CUMULUS DEVELOPMENT...BUT SAVE FOR OROGRAPHIC LIFT ALONG THE MOUNTAINS...THE SUBSIDENT HIGH PRESSURE IS NOT ALLOWING FOR ANY CONVECTIVE DEVELOPMENT. THIS SHOULD CONTINUE FOR THE NEXT COUPLE OF DAYS AS ANY SIGNIFICANT MOISTURE FEED FROM THE GULF CONTINUES TO MOVE INTO THE PLAINS AND BE SHUNTED OVER THE RIDGE INTO THE OHIO VALLEY AND GREAT LAKES. THE WAVE CURRENTLY OVER THE TEXAS/OKLAHOMA AREA WILL ALSO BE LOFTED OVER THE RIDGE AND EVENTUALLY SWALLOWED BY THE LARGER UPPER LOW WORKING ITS WAY THROUGH THE NORTHWESTERN STATES CURRENTLY AS PER THIS MORNING`S 12Z UA ANALYSIS. ALTHOUGH THE GFS STILL HAS ITS CONVECTIVE FEEDBACK ISSUES...IT IS MUCH BETTER THAN YESTERDAY AND GIVEN TIMING DIFFERENCES BETWEEN IT AND THE NAM...THE GFS IS THE MODEL OF CHOICE FOR THE SHORT TERM (ALTHOUGH GIVEN HOW LITTLE IS HAPPENING OVER THIS AREA IT REALLY DOESN`T MATTER ALL THAT MUCH). THERE ARE INDICATIONS THAT A WEAKNESS WILL DEVELOP IN THE UPPER FIELD LATE THURSDAY AND BOTH THE NAM AND GFS ARE BRINGING PRECIP TO THE GEORGIA MOUNTAINS. HOWEVER...GIVEN THE UNCERTAINTY AND INCONSISTENCY OF LATE...HAVE OPTED NOT TO ADD POPS AND WILL WAIT FOR MORE CONFIDENCE BEFORE PUTTING PRECIP IN THE FORECAST. .LONG TERM /FRIDAY THROUGH TUESDAY/... ECMWF/GFS/UKMET/DGEX ALL INDICATE A PATTERN CHANGE IN THE WORKS TOWARD THE WEEKEND AND INTO THE BEGINNING OF NEXT WEEK... TRANSITIONING INTO GENERAL TROUGHINESS OVER THE EASTERN HALF OF THE COUNTRY...BEGINNING WITH THIS UPPER LOW THAT IS MOVING INTO THE NORTHWEST PORTION OF THE COUNTRY NOW. IT IS SUPPOSED TO WRAP UP AND KICK THIS UPPER HIGH OUT...AND IN DOING SO SHOULD BRING MORE MOISTURE WITH IT AND COOLER TEMPERATURES FOR NEXT WEEK. HOWEVER...TIMING IS THE QUESTION BECAUSE YET AGAIN THE WEAK FRONTAL PASSAGE HAS BEEN PUSHED BACK ON THE GFS...BUT WITH THE DIFFERENCES BETWEEN THE MODELS THERE MAY STILL BE PRECIP LATE IN THE WEEKEND VERSUS EARLY NEXT WEEK. THE OTHER INTERESTING FEATURE IS A LOW PRESSURE SYSTEM DEVELOPING IN THE EASTERN GULF THAT CROSSES THE FLORIDA PENINSULA AND DEEPENS IN THE WESTERN ATLANTIC...THIS IS INDICATED ON BOTH THE GFS AND THE ECMWF FOR EARLY NEXT WEEK. WILL MONITOR TO SEE WHAT HAPPENS WITH IT...COULD JUST BE AN OUTLIER BUT SINCE BOTH MODELS HAVE IT...IT MIGHT BE POSSIBLE. && .AVIATION... HIGH PRESSURE REMAINING STATIONARY OVER THE NEXT 24 HRS...FROM THE CAROLINAS EASTWARD INTO THE ATLANTIC. SUBSIDENCE CONTINUES TO BE STRONG OVER GEORGIA WITH SUCH CLOSE PROXIMITY TO THIS SURFACE HIGH ALONG WITH RIDGING ALOFT. VERY DRY AIRMASS WILL LEAD TO DIURNALLY INDUCED SCATTERED MAINLY AFTERNOON CUMULUS AGAIN TOMORROW...THOUGH CEILINGS WILL REMAIN WELL INTO THE VFR RANGE. WINDS GENERALLY OUT OF AN E/SE DIRECTION THROUGH THE PERIOD AS NO SIGNIFICANT CHANGE TO THE LARGE SCALE WEATHER PATTERN IS EXPECTED. SMOKE IS REMAINING WELL SOUTH OF OUR LOCAL TERMINALS THIS AFTERNOON...AND HASN`T REACHED ANY OF OUR TAF AIRPORTS IN THE LAST 48HRS...BUT WILL STILL NEED TO KEEP A CLOSE EYE ON IT IN CASE WINDS DRAW IT TOWARD CSG OR MCN LATE TONIGHT. RRH && .PRELIMINARY POINT TEMPS/POPS... ATHENS 58 86 61 87 62 / 0 5 5 5 5 ATLANTA 65 85 65 86 64 / 0 5 5 5 5 BLAIRSVILLE 52 84 55 80 55 / 0 0 5 10 10 CARTERSVILLE 57 86 57 85 58 / 0 0 5 5 5 COLUMBUS 62 88 61 88 65 / 0 5 5 5 5 GAINESVILLE 62 86 63 84 63 / 0 5 5 10 10 MACON 58 91 60 92 63 / 0 5 5 5 5 ROME 56 88 60 84 60 / 0 0 5 10 10 PEACHTREE CITY 53 86 53 86 59 / 0 5 5 5 5 VIDALIA 63 91 62 89 64 / 0 0 5 5 5 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ TDP/15 ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 652 AM CDT TUE MAY 29 2007 .DISCUSSION REGARDING MORNING ZONES/GRIDS... 325 AM CDT MAIN FORECAST ISSUES WILL CONTINUE TO CENTER ON WARM TEMPERATURES THROUGH THE SHORT TERM...AND INCREASING CHANCES FOR CONVECTION...ESPECIALLY BY LATE WEDNESDAY INTO THURSDAY. SURFACE WARM FRONT WILL CONTINUE TO LIFT NORTHEAST THROUGH FAR NORTHEAST ILLINOIS EARLY THIS MORNING. LATEST SFC OBS INDICATING THIS TREND WITH SFC DEW PTS AT MDW HAVING INCREASED BY AROUND 10 DEGREES OVER THE LAST 2 HOURS. FURTHER SOUTH OF THE WARM FRONT WITH SFC DEW PTS IN THE MID 60S...LIGHT WINDS...AND MOSTLY CLEAR SKIES HAVE HAD SOME PATCHY FOG WITH VSBYS GENERALLY IN THE 2-4 MILE RANGE ACROSS MANY LOCATIONS. MAY HAVE SOME LOCALIZED DENSER FOG PATCHES THIS MORNING...BUT THIS SHOULD BURN OFF QUICKLY EARLY THIS MORNING. ALL OF THE FORECAST AREA WILL BE FIRMLY IN THE WARM SECTOR THIS AFTERNOON WITH 850 HPA TEMPS AROUND +15 TO +16 DEG C. MIXING DOWN THESE TEMPS SHOULD ALLOW MAX TEMPS TO REACH THE MID TO UPPER 80S WITHOUT MUCH PROBLEM TODAY. WITH SOUTH/SOUTHEAST FLOW NEAR THE LAKE TODAY...MAJORITY OF LAKE COOLING WILL OCCUR ACROSS THE LAKE COUNTY ILLINOIS SHORELINE BUT EVEN ACROSS THESE LOCATIONS HIGH TEMPS SHOULD REACH AROUND 80 GIVEN WARM AIRMASS OVER THE AREA. FORECAST AREA REMAINS UNDER THE INFLUENCE OF MID/UPPER LEVEL RIDGING THIS MORNING...HOWEVER A FEW SHORT WAVES NOTED IN UPSTREAM PROFILER DATA AND WATER VAPOR IMAGERY WILL BE LIFTING NORTHWARD THROUGH THIS UPPER RIDGE AXIS TODAY. OTHER THAN THESE WEAK SHORT WAVES...NOT MUCH ELSE TO FOCUS CONVECTIVE CHANCES TODAY WITH MODEL TIME HEIGHT SECTIONS FROM THE WRF/GFS INDICATING SYNOPTIC SCALE DOWNWARD MOTION THROUGH THIS AFTERNOON. WITH MAX TEMPS IN THE MID TO UPPER 80S AND SFC DEW PTS MIXING BACK DOWN TO AROUND 60 THIS AFTERNOON...FORECAST SOUNDINGS YIELD AROUND 200-400 J/KG OF MLCAPE TODAY. CANNOT COMPLETELY RULE OUT ISOLD SHOWER OR TSTORM TODAY BUT GIVEN WEAK SUPPORT AND PASSAGE OF ONLY WEAK SHORT WAVES THROUGH THE RIDGE...WILL KEEP FORECAST DRY. ONE THING THAT MAY NEED TO BE WATCHED IS IF WEAK MOISTURE CONVERGENCE AXIS WEST OF THE LAKE MICHIGAN SHORELINE MAY BE ENOUGH TO FOCUS ISOLD SHOWERS/TSTORMS BUT AGAIN CONFIDENCE NOT HIGH ENOUGH TO INCLUDE A MENTION. FOR TONIGHT MID/UPPER LEVEL RIDGE AXIS WILL SLOWLY SHIFT EASTWARD ALLOWING FOR MORE SUBSTANTIAL MOISTURE TRANSPORT ESPECIALLY ACROSS WESTERN PORTIONS OF THE FORECAST AREA. SEVERAL WEAK SHORT WAVES ALSO ARE EXPECTED TO LIFT NORTHWARD AND FROM UPPER LEVEL SHORT WAVE ACROSS SOUTHEAST TEXAS...BUT THIS FORCING WILL NOT LIKELY ARRIVE INTO EARLY WEDNESDAY SO WILL CONTINUE TO KEEP TUESDAY NIGHT DRY. ON WEDNESDAY...WEAK UPPER JET STREAK ASSOCIATED WITH EASTERN TX WAVE WILL LIFT INTO THE MID/UPPER MS RIVER VALLEY...AND WITH MORE IMPRESSIVE MOISTURE PROFILES ACROSS THE WEST WILL MAINTAIN CHANCE POPS FOR TSRA ACROSS NORTH CENTRAL ILLINOIS ON WEDNESDAY AFTERNOON...AND SPREAD THIS CHANCE POPS ACROSS REMAINDER OF CWA WEDNESDAY NIGHT AS RIDGE AXIS SHIFTS FAR ENOUGH EASTWARD. FOCUS FOR THURSDAY THROUGH THE WEEKEND WILL BE ON EVOLUTION OF LARGE SCALE UPPER TROUGH ACROSS THE NORTHWEST CONUS. 00Z RUNS HAVE CONTINUED TREND OF SLOWING PROGRESSION OF THIS FEATURE WITH CANADIAN SOLUTION THE SLOWEST OF THESE SOLUTIONS...AND LATTER PERIODS OF THE WRF LOOKING ON THE MORE PROGRESSIVE SIDE. WILL CONTINUE WITH MIDDLE OF THE ROAD GFS AT THIS TIME WHICH GENERALLY HAS DECENT SUPPORT FROM NCEP ENSEMBLE MEANS ALTHOUGH ENSEMBLE MEANS EVEN A BIT SLOWER THAN OPERATIONAL GFS. PERHAPS BEST CHANCE OF THUNDER REMAINDER OF WEEK WILL OCCUR ON THURSDAY AS UPPER JET MAX CUTTING THROUGH BASE OF THIS AFOREMENTIONED UPPER LOW APPROACHES EASTERN IOWA/NORTHERN ILLINOIS. HAVE KEPT HIGH END CHANCE POPS AT THIS TIME BUT MAY NEED TO NUDGE TO LIKELY POPS OVER NEXT FEW FORECASTS. GIVEN SLOWER TIMING TO UPPER LOW...HAVE EXPANDED CHANCE OF TSRA INTO SATURDAY AND NUDGED TEMPS UP TO NEAR 80 ON FRIDAY. REMAINDER OF EXTENDED LEFT AS IS. MARSILI && .AVIATION... 652 AM CDT SFC WRMFRNT APPEARS TO BE LIFTING THROUGH NERN IL AT 11Z...WITH SFC ANALYSIS INDICATING FRONT APPROXIMATELY ALONG A LINE FROM SRN LAKE MICHIGAN...TO KORD AND KJVL. SOME 2-6SM HZ/BR BEING REPORTED WITH LGT WIND FIELD AND INCRSG SFC DWPTS ALONG/SOUTH OF FRONT BUT THIS EXPECTED TO MIX OUT FIRST FEW HOURS THIS MORNING. OTHERWISE...SOME SCT MID/HIGH CLOUDS ASSOCIATED WITH ISENTROPIC UPGLIDE NOW LIFTING INTO WI WITH WEAK SHEAR/VORT AXIS NOTED IN VAPOR IMAGERY. EXPECTING SCT DIURNAL VFR CU DVLPMNT WITH BASES IN 5-6 KFT RANGE. AS MENTIONED IN PREVIOUS DISCUSSION...LOW PROBABILITY POTENTIAL FOR ISOLATED CONVECTIVE DEVELPMENT TODAY. 06Z WRF/NAM AND RUC FCST SOUDNINGS CONTINUE TO DVLP 200-500 J/KG MLCAPE WITH LITTLE OR NO CIN IN WARM/MOIST WARM SECTOR AIR MASS SOUTH OF WRMFRNT LATE MORNING THROUGH AFTN. ANOTHER WEAK MID LVL SHEAR/VORT AXIS OVER MO/SRN IL FCST TO LIFT INTO NRN IL BY LATE AFTN. NO STRONG LLVL FOCUS FOR INITIATION EVIDENT ATTM...THOUGH LAKE BREEZE DEVELOPMENT INTO NORTHEAST COOK/LAKE COUNTIES COULD PROVIDE WEAK LLVL COVERNGENCE. AT THIS POINT...HOWEVER CONFIDENCE AND POINT PROBABILITY MUCH TOO LOW TO INCLUDE ANY RW/TRW IN TAFS. AS FOR WINDS...LIGHT SOUTHEAST WINDS FROM 150-160 DEG EARLY THIS MORNING EXPECTED TO BECOME MORE SOUTH AS BOUNDARY LAYER MIXES AND WARM FRONT CONTINUES TO LIFT TO THE NORTH. 06Z MODEL GUIDANCE CONTINUES TO SUPPORT SLIGHTLY SOUTHEAST WINDS ALONG LAKE MICHIGAN SHORE WHICH WILL LIKELY ALLOW LAKE BREEZE INTO AREAS NORTH/EAST OF KORD/KMDW THIS AFTN...BUT NOT EXPECTED TO AFFECT EITHER AIRPORT. LGT SSE WINDS TO CONTINUE TONIGHT. RATZER && .MARINE... 306 AM CDT HIGH PRESSURE OVER THE EASTERN LAKES WILL SLIDE SOUTHEAST ACROSS THE MID ATLANTIC REGION THROUGH WEDNESDAY...AND OFF THE EAST COAST BY THURSDAY. MEANWHILE...A LOW PRESSURE TROUGH OVER THE HIGH PLAINS WILL MOVE VERY SLOWLY EASTWARD ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST RESULTING IN A PROLONGED PERIOD OF SOUTHERLY WINDS ACROSS LAKE MICHIGAN. THIS WILL ALSO PULL RELATIVELY WARM AIR NORTHWARD OVER THE LAKE...WHICH WILL TEND TO PRODUCE STABLE CONDITIONS OVER THE COLDER LAKE WATER AND LIMIT WIND SPEEDS TO THE 10 TO 15 KNOT RANGE OR SO. BLOCKING UPPER RIDGE OVER THE EASTERN US CONTINUES TO SUGGEST A SLOWER EASTWARD PROGRESSION OF UPPER TROUGH OVER NRN RCKYS/NRN PLAINS NEXT SVRL DAYS. CURRENT NUMERICAL MODEL FORECASTS CONTINUE TO SLOW APPROACH OF SURFACE LOW AND COLD FRONT ASSOCIATED WITH THIS SYSTEM...WHICH MAY NOT MOVE TO LAKE MICHIGAN UNTIL THE WEEKEND. VARIOUS NUMERICAL GUIDANCE ALSO DIFFERS WITH HOW FAR SOUTH A COLD FRONT SAGS FROM CANADA OVER NORTHERN LAKE MICHIGAN IN THURSDAY NIGHT THROUGH FRIDAY NIGHT TIMEFRAME...BUT SOME GLOBAL MODEL CONSENSUS IN A FARTHER SOUTH SOLUTION. HAVE BROUGHT WINDS AROUND ON NORTHERN LAKE MICHIGAN BASED ON THIS THINKING AND IN COLLABORATION WITH WFOS AROUND NORTHERN LAKE MICHIGAN. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 306 AM CDT TUE MAY 29 2007 .DISCUSSION REGARDING AFTERNOON ZONES/GRIDS... 300 PM CDT NO SIG CHGS MADE TO FCST. HAVE MADE SOME ADJUSTMENTS TO NR TERM OF FCST BASED ON CURRENT SATLT/RADAR TRENDS. SFC ANALYSIS AND CLOUD TRENDS SHOW CONVECTION DVLPG ALONG SFC DEW POINT DISCONTINUITY ASSD WITH OLD FRONTAL BOUNDARY FROM NR DBQ-MMO-IKK-NR LAF. THIS BOUNDARY HAS BEEN LIFTING SLOWLY NWD AND THIS MOVEMENT SHOULD CONTINUE. AM SOMEWHAT SURPRISED AT LOCATION OF THIS CONVECTION AS AREA HAS BEEN CLOUD COVERED MOST OF DAY LIMITING SFC BASED INSTABILITY...AND ACARS/PROFILER DATA SHOWS VERY LIMITED LLVL WIND FLOW INTO MID MS VLY AND POINTS EWD. NONETHELESS...VIS IMAGERY SHOWS CLOUD TEXTURE INCRSG ALG WARM FRONT SUGGESTING POTL FOR SHOWERS TO CONT BUILDING WWD INTO PORTIONS OF N CNTRL-NERN IL. EXPECT THIS AREA OF WARM FRONT TO BECOME INACTIVE AS EVENING WEARS ON...BUT WILL MENTION CHC POPS FOR SCT SHWRS...PERHAPS SOME THUNDER AS BOUNDARY LIFTS NWD ACROSS FA. BETTER LLVL FORCING/NOCTURNAL TSTM POTL TO REFOCUS TO W AS LLJ STRENGTHENS FROM KS NNEWD INTO MN-NWRN WI OVERNIGHT. SFC DEW POINTS TO CREEP UP TO ARND 60 OVR ENTIRE FA OVERNIGHT AS RGN GETS INTO WARM SECTOR. THERFORE...HAVE GONE WITH HIGHER NAM MOS NUMBER ON MINS TNGT. WILL GO DRY TUES-TUES NIGHT AS CONVECTION INCREASES AND CONTINUES TO FOCUS ALONG SLOW MOVG N-S ORIENTED BOUNDARY OVR PLAINS STAS AND AS DEEP TROF OVR NRN RCKYS EVOLVES INTO CLOSED LOW. THIS WILL INDUCE INCREASE IN H5 HGTS E OF MS RVR DURG THIS TIME FRAME. WITH DECENT HEATING OF WARM SECTOR...EXPECT CU FIELD TO DVLP IN WARM/SOMEWHAT HUMID AMS OVR RGN...BUT AGAIN...WITH SUBSIDENT AIR FCST OVR RGN WILL FAVOR DRY FCST FOR NOW. EVENTUALLY...CLOSED LOW OVR NRN PLAINS FCST TO DVLP NEG TILT TROF ALG ITS PERIPHERY...ALLOWING AXES OF DEEPER LLVL MOISTURE AND MORE SIG LLVL WIND FLOW TO SHIFT SLOWLY EWD...INCRSG TSTM CHCS OVR RGN. HOWEVER...WILL JUST CONTINUE EXTENDED PERIOD OF CHC POPS FROM WED/WED AFTN THRU FRI NGT AS AREA WILL RMN IN MT AIR MASS. HOWEVER...JUST BETWEEN YOU AND ME...I WOULD EXPECT TSTM CHCS/COVG TO INCREASE AS WEEK GOES ON AS H5 HGTS LWR AND IMPULSES ROTATE AROUND DEEP UPR LOW OVER NRN PLAINS. WILL CONT WITH DRY FCST OVR WEEKEND AS UPR LOW PASSES TO N ALLOWING DRIER AIR TO ADVECT INT FROM W AND LLVL WINDS VEER INTO W-NW WITH TIME. MERZLOCK && .AVIATION... 1256 AM CDT 05Z SFC ANALYSIS INDICATES WARM FRONT STRETCHING ACROSS FCST AREA JUST OFF TO THE SOUTH OF TERMINALS...ROUGHLY KDBQ...KJOT...KVPZ. LLVL WINDS FAIRLY WEAK IN DECOUPLED BOUNDARY LAYER...THOUGH FRONT EXPECTED TO CONTINUE TO DRIFT SLOWLY NORTH ACROSS FCST AREA OVRNGT. SFC DWPTS IN LOWER 60S IN WARM SECTOR...WITH SVRL AWOS SITES SOUTH OF THE WARMFRONT REPORTING MVFR VIS RESTRICTIONS IN HZ/BR. EXPECT TERMINAL SITES TO FOLLOW THIS TREND WITH 3-5SM LIKELY AS FRONT LIFTS NORTH OVRNGT...THOUGH URBAN INFLUENCE EXPECTED TO KEEP KMDW/KORD VFR. VSBYS EXPECTED TO IMPROVE TO VFR ALL LOCATIONS WITHING A COUPLE HOURS AFTER SUNRISE. OTHERWISE...SOME SCT MID/HIGH CLOUDS ASSOCIATED WITH WEAK WARM/MOIST ADVCTN AND OCNL SHEARED S/WVS THRU THE TAF PERIOD. DIRUNAL CU ALSO XPCTD WITH BASES IN 5-6KFT RANGE. WINDS NORTH OF FRONT ESE 110-130 DEG...BUT ARE EXPECTED TO VEER MORE SOUTH TOWARD 160-170 DEG AS FRONT MOVES NORTH THIS MORNING. WEAK SOUTHEAST LAKE BREEZE XPCTD TO DVLP THIS AFTN BUT SHOULD REMAIN EAST OF AIRPORTS AND NOT AFFECT KORD/KMDW DIRECTLY. SHOULD NOTE THAT BOTH WRF AND RUC HINT AT MINIMAL CONVECTIVE POTENTIAL TODAY. FCST SOUNDINGS FOR POINTS IN CENTRAL FCST AREA INDICATE SBCAPES AS HIGH AS 1500 J/KG AND LITTLE/NO CIN LATE MORNING/AFTN. HOWEVER...WITH WARM FRONT LIFTING NORTH OF FCST AREA NO WELL DEFINED LLVL FOCUS FOR DVLPMNT. WHILE CANT RULE OUT ISOLATED RW/TRW DVLPG SOMEWHERE IN VCNTY TODAY...POINT PROBABILITY FAR TOO LOW TO INCLUDE IN TAF ATTM. RATZER && .MARINE... 306 AM CDT HIGH PRESSURE OVER THE EASTERN LAKES WILL SLIDE SOUTHEAST ACROSS THE MID ATLANTIC REGION THROUGH WEDNESDAY...AND OFF THE EAST COAST BY THURSDAY. MEANWHILE...A LOW PRESSURE TROUGH OVER THE HIGH PLAINS WILL MOVE VERY SLOWLY EASTWARD ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST RESULTING IN A PROLONGED PERIOD OF SOUTHERLY WINDS ACROSS LAKE MICHIGAN. THIS WILL ALSO PULL RELATIVELY WARM AIR NORTHWARD OVER THE LAKE...WHICH WILL TEND TO PRODUCE STABLE CONDITIONS OVER THE COLDER LAKE WATER AND LIMIT WIND SPEEDS TO THE 10 TO 15 KNOT RANGE OR SO. BLOCKING UPPER RIDGE OVER THE EASTERN US CONTINUES TO SUGGEST A SLOWER EASTWARD PROGRESSION OF UPPER TROUGH OVER NRN RCKYS/NRN PLAINS NEXT SVRL DAYS. CURRENT NUMERICAL MODEL FORECASTS CONTINUE TO SLOW APPROACH OF SURFACE LOW AND COLD FRONT ASSOCIATED WITH THIS SYSTEM...WHICH MAY NOT MOVE TO LAKE MICHIGAN UNTIL THE WEEKEND. VARIOUS NUMERICAL GUIDANCE ALSO DIFFERS WITH HOW FAR SOUTH A COLD FRONT SAGS FROM CANADA OVER NORTHERN LAKE MICHIGAN IN THURSDAY NIGHT THROUGH FRIDAY NIGHT TIMEFRAME...BUT SOME GLOBAL MODEL CONSENSUS IN A FARTHER SOUTH SOLUTION. HAVE BROUGHT WINDS AROUND ON NORTHERN LAKE MICHIGAN BASED ON THIS THINKING AND IN COLLABORATION WITH WFOS AROUND NORTHERN LAKE MICHIGAN. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...NONE. && $$ il AREA FORECAST DISCUSSION...UPDATED... NATIONAL WEATHER SERVICE QUAD CITIES IA IL 705 AM CDT MON MAY 28 2007 .UPDATE...CONVECTION BREAKING OUT EVEN FASTER THAN THOUGHT. HAVE UPDATED FCST TO REFLECT SCATTERED SHRA GETTING UP TO AT LEAST HIGHWAY 30 BY 15Z. CURRENT RADAR TRENDS SUGGEST SOME CELLS ARE GETTING CLOSE TO PRODUCING LIGHTNING SO HAVE MOVED FORWARD THE DEVELOPMENT OF THUNDER AS WELL. ...08... /PREVIOUS DISCUSSION/... .SYNOPSIS... A WARM FRONT WILL MOVE NORTH ACROSS THE REGION TODAY BRINGING A CHANCE OF RAIN TO THE AREA. THE UNSETTLED WEATHER PATTERN WILL CONTINUE FOR MUCH OF THE WEEK AS YET ANOTHER COLD FRONT MOVES THROUGH THE REGION SHORTLY AFTER THE MIDDLE OF THE WORK WEEK. && .SHORT TERM...TODAY AND TONIGHT... STALLED FRONT HAS YET TO SHOW ANY MOVEMENT NORTH FROM MISSOURI. HOWEVER...WEAK WAA HAS RESULTED IN SOME ISOLATED/SCATTERED SHOWERS DEVELOPING SOUTH OF HIGHWAY 34. 06Z RUC SHOWS DEEPER MOISTURE ADVECTING NORTH DURING THE DAY...SO MORE PRECIP SHOULD SLOWLY BREAK OUT DURING THE DAY. MODELS SUGGEST A WEAK SHORTWAVE TO MOVE THROUGH THE AREA TONIGHT WHICH MAY HELP KEEP NOCTURNAL CONVECTION GOING. ...08... .LONG TERM...TUESDAY THROUGH SUNDAY... WHILE THE STORY HAS CHANGED IN THE FORECAST THROUGHOUT THE EXTENDED...IT SURE LOOKS LIKE IT WILL BE READ SLOWER. 00Z MODELS HAVE CONTINUED THE TREND ON SLOWING THE PROGRESSION OF THE UPPER LOWS EASTWARD MOVEMENT. THE MODEL SPREAD NOW IS FAVORING IN THE SLOWER GFS...WHICH KEEPS US IN THE MOISTURE LONGER AS THE SURFACE FRONT LINGERS THROUGH FRIDAY. THIS ADJUSTMENT WILL HAVE TWO MAJOR AFFECTS ON THE FORECAST...ONE WE WILL NEED TO DECREASE POP COVERAGE TUESDAY THROUGH WEDNESDAY...AS THE FRONT LOOKS TO REMAIN FAR ENOUGH WEST THAT CONVECTION MAY BE RATHER SCATTERED OR ISOLATED. NEXT...WEDNESDAY NIGHT THROUGH FRIDAY APPEAR QUITE WET...BUT WILL MAKE SOME BABY STEPS TONIGHT...AND INCREASE POPS TO CHANCE RANGE THU AND THURSDAY NIGHT...AND POPS FRIDAY. SHOULD THIS MODEL TREND CONTINUE...WE NEED MUCH HIGHER POPS...AND MAY NEED TO LINGER THINGS INTO THE WEEKEND. THIS PAST MONTH WE HAVE SEEN SEVERAL LONG DURATION UPPER LOWS IN THE PLAINS BRING EXTENSIVE RAINS TO LOCATIONS WEST OF OUR CWA...AND THIS COULD BE A PATTERN THAT BRINGS SIMILAR CONDITIONS HERE...BUT AS ALWAYS...TIME WILL TELL. TEMPERATURES WILL BE HELD CLOSE TO PREVIOUS FORECASTS...BUT STILL GENERALLY REFLECTS NEAR SEASONAL LEVELS...WITH RATHER HIGH DEWPOINTS IN THE 60S. ...ERVIN... && .AVIATION... BETTER WAA STILL REMAINING ACROSS WESTERN IOWA. HOWEVER...THE WAA THAT IS OCCURRING IS ALLOWING SOME NOCTURNAL SHRA TO DEVELOP JUST SOUTH OF THE KBRL AREA. STALLED FRONT ACROSS NORTHERN MISSOURI TO SLOWLY MOVE BACK NORTH DURING THE DAY AND ALLOW CLOUDS TO DEVELOP IN THE 3-4KFT AGL LAYER. CIGS TO EVENTUALLY BE AROUND 4KFT AGL BUT WOULD NOT BE SURPRISED IF SOME 3KFT CIGS DEVELOP. OVERALL CURRENTLY DEVELOPING CONVECTION SHOULD BECOME MORE NUMEROUS WITH TSRA DEVELOPING DURING THE DAY. ...08... && DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ 08/ERVIN ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 258 AM CDT MON MAY 28 2007 .SYNOPSIS... A WARM FRONT WILL MOVE NORTH ACROSS THE REGION TODAY BRINGING A CHANCE OF RAIN TO THE AREA. THE UNSETTLED WEATHER PATTERN WILL CONTINUE FOR MUCH OF THE WEEK AS YET ANOTHER COLD FRONT MOVES THROUGH THE REGION SHORTLY AFTER THE MIDDLE OF THE WORK WEEK. && .SHORT TERM...TODAY AND TONIGHT... STALLED FRONT HAS YET TO SHOW ANY MOVEMENT NORTH FROM MISSOURI. HOWEVER...WEAK WAA HAS RESULTED IN SOME ISOLATED/SCATTERED SHOWERS DEVELOPING SOUTH OF HIGHWAY 34. 06Z RUC SHOWS DEEPER MOISTURE ADVECTING NORTH DURING THE DAY...SO MORE PRECIP SHOULD SLOWLY BREAK OUT DURING THE DAY. MODELS SUGGEST A WEAK SHORTWAVE TO MOVE THROUGH THE AREA TONIGHT WHICH MAY HELP KEEP NOCTURNAL CONVECTION GOING. ...08... .LONG TERM...TUESDAY THROUGH SUNDAY... WHILE THE STORY HAS CHANGED IN THE FORECAST THROUGHOUT THE EXTENDED...IT SURE LOOKS LIKE IT WILL BE READ SLOWER. 00Z MODELS HAVE CONTINUED THE TREND ON SLOWING THE PROGRESSION OF THE UPPER LOWS EASTWARD MOVEMENT. THE MODEL SPREAD NOW IS FAVORING IN THE SLOWER GFS...WHICH KEEPS US IN THE MOISTURE LONGER AS THE SURFACE FRONT LINGERS THROUGH FRIDAY. THIS ADJUSTMENT WILL HAVE TWO MAJOR AFFECTS ON THE FORECAST...ONE WE WILL NEED TO DECREASE POP COVERAGE TUESDAY THROUGH WEDNESDAY...AS THE FRONT LOOKS TO REMAIN FAR ENOUGH WEST THAT CONVECTION MAY BE RATHER SCATTERED OR ISOLATED. NEXT...WEDNESDAY NIGHT THROUGH FRIDAY APPEAR QUITE WET...BUT WILL MAKE SOME BABY STEPS TONIGHT...AND INCREASE POPS TO CHANCE RANGE THU AND THURSDAY NIGHT...AND POPS FRIDAY. SHOULD THIS MODEL TREND CONTINUE...WE NEED MUCH HIGHER POPS...AND MAY NEED TO LINGER THINGS INTO THE WEEKEND. THIS PAST MONTH WE HAVE SEEN SEVERAL LONG DURATION UPPER LOWS IN THE PLAINS BRING EXTENSIVE RAINS TO LOCATIONS WEST OF OUR CWA...AND THIS COULD BE A PATTERN THAT BRINGS SIMILAR CONDITIONS HERE...BUT AS ALWAYS...TIME WILL TELL. TEMPERATURES WILL BE HELD CLOSE TO PREVIOUS FORECASTS...BUT STILL GENERALLY REFLECTS NEAR SEASONAL LEVELS...WITH RATHER HIGH DEWPOINTS IN THE 60S. ...ERVIN... && .AVIATION... BETTER WAA STILL REMAINING ACROSS WESTERN IOWA. HOWEVER...THE WAA THAT IS OCCURRING IS ALLOWING SOME NOCTURNAL SHRA TO DEVELOP JUST SOUTH OF THE KBRL AREA. STALLED FRONT ACROSS NORTHERN MISSOURI TO SLOWLY MOVE BACK NORTH DURING THE DAY AND ALLOW CLOUDS TO DEVELOP IN THE 3-4KFT AGL LAYER. CIGS TO EVENTUALLY BE AROUND 4KFT AGL BUT WOULD NOT BE SURPRISED IF SOME 3KFT CIGS DEVELOP. OVERALL CURRENTLY DEVELOPING CONVECTION SHOULD BECOME MORE NUMEROUS WITH TSRA DEVELOPING DURING THE DAY. ...08... && DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ 08/ERVIN ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 855 PM MDT MON MAY 28 2007 .UPDATE... AT 0245Z THUNDERSTORMS INITIALLY CONFINED TO AREAS JUST NORTH OF OUR FORECAST AREA HAVE BEGUN TO SPREAD SOUTHWARD ALONG AN OUTFLOW BOUNDARY. 02Z RUC HAS A BULLSEYE OF 700 THETA-E CONVERGENCE OVER THE SMALL CONVECTIVE BLOB JUST TO OUR NORTH WHICH HAS PRODUCED WIDESPREAD FLOODING. FOR THE EVENING UPDATE HAVE USED THE DISTANCE SPEED TOOL WHICH SHOWS A 15 MPH EASTWARD MOVEMENT OF THE LINE OF THUNDERSTORMS. AS A RESULT HAVE UPPED THE POPS ACROSS THE NEBRASKA COUNTIES TO CATEGORICAL...TAPERING TO CHANCE AS ONE MOVES SOUTH ALONG THE BOUNDARY. THIS MATCHES BEAUTIFULLY WITH LBF GRIDS. OTHER ADJUSTMENTS WERE TO INCREASE THE CLOUDS ACROSS THE EASTERN 1/2 OF THE AREA OVERNIGHT TO CLOUDY AS BOUNDARY LAYER MOISTURE INCREASES ON SOUTHEASTERLY WINDS. RUC FORECASTS SHOW NO FOG FORMATION AT PRESENT TIME SO HAVE LEFT IT OUT. WILL WATCH FOR TRENDS ALONG THE LINE OF STORMS AND ADJUST AS NEED BE THE REST OF THE EVENING. && .AVIATION... TSRA SHOULD REMAIN NORTH OF THE KGLD AIRPORT AND REACH THE KMCK AIRPORT AROUND 06Z. WILL AMEND THE KMCK TAF ACCORDINGLY. STILL EXPECT STRATUS AT BOTH SITES AFTER MIDNIGHT WHICH IS ALREADY HANDLED WELL IN TAFS...MAY NEED TO LOWER CIGS BUT FOR NOW ITS A GOOD START. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ DDT ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAKE CHARLES LA 1036 PM CDT MON MAY 28 2007 .UPDATE... WINDS CONTINUE TO INCREASE ACROSS THE WESTERN COASTAL WATERS WITH LAPS ANALYSIS SHOWING WINDS IN THE 20 KNOTS RANGE NEARSHORE AND APPROACHING 30 KNOTS IN THE OUTER ZONES. OFFSHORE REPORTS CONCUR WITH SEA RIM OBSERVATION SUSTAINED AT 25 KNOTS...BUOY 42035 SHOWING WINDS GUSTING TO 27 KNOTS AND SEAS RISING TO 6 FEET...AND AN OIL RIG REPORT FROM 15 MILES SOUTH OF HIGH ISLAND INDICATING WINDS OF 25 TO 30 KNOTS AND SEAS 6 TO 8 FEET. WILL ISSUE SMALL CRAFT ADVISORY FOR WESTERN COASTAL WATERS. UPDATE OUT SHORTLY. SHAMBURGER && .PREV DISCUSSION... /ISSUED 950 PM CDT MON MAY 28 2007/ UPDATE... DIFFICULT FORECAST FOR TONIGHT WITH MODELS HAVING LITTLE GRASP OF CURRENT SITUATION THUS CAUSING CONSIDERABLE UNCERTAINTY. VERY MOIST AIRMASS CONTINUES TO BE IN PLACE OVER THE CWA WITH 00Z KLCH SOUNDING SHOWING A NEARLY SATURATED COLUMN WITH A PWAT OF 1.77 INCHES AND SOUTHERLY FLOW FROM THE SURFACE TO THE TROPOPAUSE. OUR EASTERN AREAS CONTINUE TO SEE FAIRLY WIDESPREAD LIGHT TO MODERATE RAINFALL BUT IN CONTRAST ALL ACTIVITY OVER OUR WESTERN AREAS HAS DISSIPATED. MEANWHILE A LARGE AREA OF RAIN AND THUNDERSTORMS EXISTS IN OUR COASTAL WATERS AND IS CURRENTLY MOVING ONSHORE ACROSS SOUTHWEST AND SOUTH-CENTRAL LOUISIANA. OTHER SHOWERS AND STORMS WERE BEGINNING TO DEVELOP ACROSS THE WESTERN COASTAL WATERS ONCE AGAIN. GFS HAS SIGNIFICANT CONVECTIVE FEEDBACK ON THE 18Z RUN AND SHOWS A INTENSE CONVECTIVE BOMB MOVING ONSHORE THROUGH THE WEST-CENTRAL PORTIONS OF THE CWA OVERNIGHT. QUICK LOOK AT 00Z NAM KEEPS MOST ACTIVITY OFFSHORE TONIGHT...AND RUC KEEPS MOST OF THE CWA DRY. NONE OF THE MODELS SEEMS REALISTIC AS DEPICTED BY CURRENT SATELLITE AND RADAR TRENDS. THUS WILL DISREGARD SHORT TERM MODELS AND BASED ON PRESENT TRENDS HAVE BUMPED UP POPS TO LIKELY ACROSS LOUISIANA ZONES AS OFFSHORE COMPLEX OF RAIN AND THUNDERSTORMS MOVES INLAND...AND LOWERED POPS ACROSS SOUTHEAST TEXAS. HAVE ALSO RAISED POPS TO LIKELY WEST AND CATEGORICAL EAST ACROSS THE COASTAL WATERS. WITH THE WIDESPREAD RAIN AND CLOUD COVER TEMPERATURES HAVE ALREADY FALLEN TO NEAR OR BELOW EXPECTED LOWS FOR TONIGHT ACROSS SOUTHERN ZONES. HAVE LOWERED MINIMUM TEMPS A COUPLE OF DEGREES TO ACCOUNT. HAVE ALSO RAISED WINDS ACROSS THE COASTAL WATERS WHERE PRESSURE GRADIENT CONTINUES TO BE TIGHT AND HAVE HOISTED EXERCISE CAUTION FLAGS ACROSS THE WESTERN OUTER WATERS. IN ADDITION...SEVERAL WATERSPOUTS OCCURRED EARLIER TODAY ACROSS OUR COASTAL WATERS AND ANALYSIS INDICATES ADDITIONAL WATERSPOUTS REMAIN POSSIBLE OVERNIGHT AND AGAIN TOMORROW. FINALLY...HEAVIEST RAINS TODAY HAVE MAINLY BEEN OFFSHORE WITH RADAR ESTIMATING WELL OVER 10 INCHES FALLING IN THE NORTHERN GULF. HOWEVER WITH CONSIDERABLE ADDITIONAL RAINFALL EXPECTED NEXT FEW DAYS A FLOOD WATCH MAY BE NECESSARY. WITH CONTINUED UNCERTAINTY OVER RAINFALL AMOUNTS WILL FOREGO ISSUANCE FOR NOW AND LET MIDNIGHT SHIFT FURTHER EVALUATE SITUATION. UPDATED GRIDS AND ZONES ALREADY SENT. THANKS TO WFO LIX FOR COORDINATION! SHAMBURGER PREV DISCUSSION... /ISSUED 328 PM CDT MON MAY 28 2007/ DISCUSSION... WATER VAPOR IMAGERY CONTINUES TO SHOW SHORTWAVE CROSSING ERN TX WITH DEEP MOISTURE AHEAD OF IT SPREADING NWD ACROSS THE FORECAST AREA. AT THE SURFACE BERMUDA HI PRES REMAINS THE STORY KEEPING SERLY LO-LVL FLOW IN PLACE PROVIDING ADDITIONAL MOISTURE. REGIONAL 88DS SHOW WIDESPREAD RW AND A FEW THUNDERSTORMS OVER THE WRN PORTION OF THE AREA ATTM WITH ANOTHER LARGE BATCH OF RAIN WITH EMBEDDED THUNDER OVER THE GULF AND APPROACHING THE COASTLINE. THEME FOR THE NEXT COUPLE OF DAYS APPEARS TO BE RAIN...ESPECIALLY TONIGHT INTO TUESDAY. AREA OF RAIN/TRW ROTATING OVER THE NWRN GULF WILL CONTINUE TOWARD THE COAST THROUGH THE AFTERNOON. AGREE IN THINKING WITH HGX THAT HOPEFULLY SUNSET WILL BRING AN END TO SOME OF THIS ACTIVITY...HOWEVER THE COVERAGE IS SO HIGH ATTM THAT I WILL GO WITH LIKELY POPS FOR TONIGHT OVER THE WRN 1/2 OF THE AREA...40 PERCENT FOR THE REMAINDER. HAVE GONE LIKELY POPS ACROSS THE ENTIRE FORECAST AREA FOR TUESDAY AS LO/SHORTWAVE MOVES FARTHER EAST AND CENTERS ITSELF OVER THE AREA. THIS FEATURE ALONG WITH GOOD DIFLUENCE ALOFT AND HIGH MOISTURE VALUES (MODEL SOUNDINGS SHOW NEAR SATURATION AND PWAT VALUES NEAR 2 INCHES) SHOULD PROVIDE THE IMPETUS FOR NUMEROUS RW/TRW. GFS/NAM PROG THESE FEATURES TO EITHER STALL OVER OR MOVE JUST EAST OF THE AREA BY WEDNESDAY AND HAVE RAISED POPS TO HIGH CHANCE FOR THEN. IF THIS TREND PLAYS OUT LATER SHIFTS WILL HAVE TO GIVE SOME THOUGHT TO GOING WITH A FLOOD WATCH...HAVE ELECTED TO HOLD OFF ON SUCH A CALL ATTM AS ANTECEDENT SOIL MOISTURE CONDITIONS APPEAR TO BY MORE THAN DRY ENOUGH TO TAKE THE RAIN WE`VE GOTTEN THE LAST DAY OR SO. THINGS LOOK TO QUIET DOWN BY THE WEEKEND AS THE MID/UPR-LVL SYSTEM MOVES OFF TO THE EAST AND DRIER AIR BEGINS TO FILTER INTO THE REGION ON WEAK RIDGING ALOFT. HOWEVER CONDITIONS STILL LOOK FAVORABLE FOR AT LEAST SOME WIDELY SCATTERED CONVECTIVE DEVELOPMENT EACH AFTERNOON. AVIATION...INTERMITTENT SHRA/TSRA EXPECTED AT ALL SITES FOR THE REMAINDER OF THE AFTERNOON...LIKELY CONTINUING THIS EVENING AND OVERNIGHT. VISBY AND CEILING WILL BE BELOW 3000FT DURING PERIODS OF SHRA/TSRA THIS AFTERNOON...BECOMING THE PRODOMINENT AFTER MIDNIGHT THRU SUNRISE. && .PRELIMINARY POINT TEMPS/POPS... KLCH 68 82 70 82 / 60 60 40 50 KBPT 68 82 71 84 / 40 60 40 50 KAEX 68 82 69 82 / 60 60 40 50 KLFT 69 83 69 83 / 60 60 40 50 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...SMALL CRAFT ADVISORY UNTIL 7 AM TUESDAY FOR THE FOLLOWING ZONES: COASTAL WATERS FROM CAMERON, LA TO HIGH ISLAND, TX OUT 20 NM...AND WATERS FROM CAMERON, LA TO HIGH ISLAND, TX EXTENDING FROM 20 NM TO 60 NM. && $$ la AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE LAKE CHARLES LA 950 PM CDT MON MAY 28 2007 .UPDATE... DIFFICULT FORECAST FOR TONIGHT WITH MODELS HAVING LITTLE GRASP OF CURRENT SITUATION THUS CAUSING CONSIDERABLE UNCERTAINTY. VERY MOIST AIRMASS CONTINUES TO BE IN PLACE OVER THE CWA WITH 00Z KLCH SOUNDING SHOWING A NEARLY SATURATED COLUMN WITH A PWAT OF 1.77 INCHES AND SOUTHERLY FLOW FROM THE SURFACE TO THE TROPOPAUSE. OUR EASTERN AREAS CONTINUE TO SEE FAIRLY WIDESPREAD LIGHT TO MODERATE RAINFALL BUT IN CONTRAST ALL ACTIVITY OVER OUR WESTERN AREAS HAS DISSIPATED. MEANWHILE A LARGE AREA OF RAIN AND THUNDERSTORMS EXISTS IN OUR COASTAL WATERS AND IS CURRENTLY MOVING ONSHORE ACROSS SOUTHWEST AND SOUTH-CENTRAL LOUISIANA. OTHER SHOWERS AND STORMS WERE BEGINNING TO DEVELOP ACROSS THE WESTERN COASTAL WATERS ONCE AGAIN. GFS HAS SIGNIFICANT CONVECTIVE FEEDBACK ON THE 18Z RUN AND SHOWS A INTENSE CONVECTIVE BOMB MOVING ONSHORE THROUGH THE WEST-CENTRAL PORTIONS OF THE CWA OVERNIGHT. QUICK LOOK AT 00Z NAM KEEPS MOST ACTIVITY OFFSHORE TONIGHT...AND RUC KEEPS MOST OF THE CWA DRY. NONE OF THE MODELS SEEMS REALISTIC AS DEPICTED BY CURRENT SATELLITE AND RADAR TRENDS. THUS WILL DISREGARD SHORT TERM MODELS AND BASED ON PRESENT TRENDS HAVE BUMPED UP POPS TO LIKELY ACROSS LOUISIANA ZONES AS OFFSHORE COMPLEX OF RAIN AND THUNDERSTORMS MOVES INLAND...AND LOWERED POPS ACROSS SOUTHEAST TEXAS. HAVE ALSO RAISED POPS TO LIKELY WEST AND CATEGORICAL EAST ACROSS THE COASTAL WATERS. WITH THE WIDESPREAD RAIN AND CLOUD COVER TEMPERATURES HAVE ALREADY FALLEN TO NEAR OR BELOW EXPECTED LOWS FOR TONIGHT ACROSS SOUTHERN ZONES. HAVE LOWERED MINIMUM TEMPS A COUPLE OF DEGREES TO ACCOUNT. HAVE ALSO RAISED WINDS ACROSS THE COASTAL WATERS WHERE PRESSURE GRADIENT CONTINUES TO BE TIGHT AND HAVE HOISTED EXERCISE CAUTION FLAGS ACROSS THE WESTERN OUTER WATERS. IN ADDITION...SEVERAL WATERSPOUTS OCCURRED EARLIER TODAY ACROSS OUR COASTAL WATERS AND ANALYSIS INDICATES ADDITIONAL WATERSPOUTS REMAIN POSSIBLE OVERNIGHT AND AGAIN TOMORROW. FINALLY...HEAVIEST RAINS TODAY HAVE MAINLY BEEN OFFSHORE WITH RADAR ESTIMATING WELL OVER 10 INCHES FALLING IN THE NORTHERN GULF. HOWEVER WITH CONSIDERABLE ADDITIONAL RAINFALL EXPECTED NEXT FEW DAYS A FLOOD WATCH MAY BE NECESSARY. WITH CONTINUED UNCERTAINTY OVER RAINFALL AMOUNTS WILL FOREGO ISSUANCE FOR NOW AND LET MIDNIGHT SHIFT FURTHER EVALUATE SITUATION. UPDATED GRIDS AND ZONES ALREADY SENT. THANKS TO WFO LIX FOR COORDINATION! SHAMBURGER && .PREV DISCUSSION... /ISSUED 328 PM CDT MON MAY 28 2007/ DISCUSSION... WATER VAPOR IMAGERY CONTINUES TO SHOW SHORTWAVE CROSSING ERN TX WITH DEEP MOISTURE AHEAD OF IT SPREADING NWD ACROSS THE FORECAST AREA. AT THE SURFACE BERMUDA HI PRES REMAINS THE STORY KEEPING SERLY LO-LVL FLOW IN PLACE PROVIDING ADDITIONAL MOISTURE. REGIONAL 88DS SHOW WIDESPREAD RW AND A FEW THUNDERSTORMS OVER THE WRN PORTION OF THE AREA ATTM WITH ANOTHER LARGE BATCH OF RAIN WITH EMBEDDED THUNDER OVER THE GULF AND APPROACHING THE COASTLINE. THEME FOR THE NEXT COUPLE OF DAYS APPEARS TO BE RAIN...ESPECIALLY TONIGHT INTO TUESDAY. AREA OF RAIN/TRW ROTATING OVER THE NWRN GULF WILL CONTINUE TOWARD THE COAST THROUGH THE AFTERNOON. AGREE IN THINKING WITH HGX THAT HOPEFULLY SUNSET WILL BRING AN END TO SOME OF THIS ACTIVITY...HOWEVER THE COVERAGE IS SO HIGH ATTM THAT I WILL GO WITH LIKELY POPS FOR TONIGHT OVER THE WRN 1/2 OF THE AREA...40 PERCENT FOR THE REMAINDER. HAVE GONE LIKELY POPS ACROSS THE ENTIRE FORECAST AREA FOR TUESDAY AS LO/SHORTWAVE MOVES FARTHER EAST AND CENTERS ITSELF OVER THE AREA. THIS FEATURE ALONG WITH GOOD DIFLUENCE ALOFT AND HIGH MOISTURE VALUES (MODEL SOUNDINGS SHOW NEAR SATURATION AND PWAT VALUES NEAR 2 INCHES) SHOULD PROVIDE THE IMPETUS FOR NUMEROUS RW/TRW. GFS/NAM PROG THESE FEATURES TO EITHER STALL OVER OR MOVE JUST EAST OF THE AREA BY WEDNESDAY AND HAVE RAISED POPS TO HIGH CHANCE FOR THEN. IF THIS TREND PLAYS OUT LATER SHIFTS WILL HAVE TO GIVE SOME THOUGHT TO GOING WITH A FLOOD WATCH...HAVE ELECTED TO HOLD OFF ON SUCH A CALL ATTM AS ANTECEDENT SOIL MOISTURE CONDITIONS APPEAR TO BY MORE THAN DRY ENOUGH TO TAKE THE RAIN WE`VE GOTTEN THE LAST DAY OR SO. THINGS LOOK TO QUIET DOWN BY THE WEEKEND AS THE MID/UPR-LVL SYSTEM MOVES OFF TO THE EAST AND DRIER AIR BEGINS TO FILTER INTO THE REGION ON WEAK RIDGING ALOFT. HOWEVER CONDITIONS STILL LOOK FAVORABLE FOR AT LEAST SOME WIDELY SCATTERED CONVECTIVE DEVELOPMENT EACH AFTERNOON. AVIATION...INTERMITTENT SHRA/TSRA EXPECTED AT ALL SITES FOR THE REMAINDER OF THE AFTERNOON...LIKELY CONTINUING THIS EVENING AND OVERNIGHT. VISBY AND CEILING WILL BE BELOW 3000FT DURING PERIODS OF SHRA/TSRA THIS AFTERNOON...BECOMING THE PRODOMINENT AFTER MIDNIGHT THRU SUNRISE. && .PRELIMINARY POINT TEMPS/POPS... KLCH 68 82 70 82 / 60 60 40 50 KBPT 68 82 71 84 / 40 60 40 50 KAEX 68 82 69 82 / 60 60 40 50 KLFT 69 83 69 83 / 60 60 40 50 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...SMALL CRAFT EXERCISE CAUTION GMZ470. && $$ la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CARIBOU ME 1110 AM EDT MON MAY 28 2007 .SYNOPSIS... LOW PRESSURE WILL PASS NORTH OF THE STATE WHILE PULLING A COLD FRONT ACROSS THE REGION THIS AFTERNOON INTO THIS EVENING. HIGH PRESSURE WILL BUILD IN FROM THE WEST ON TUESDAY. A FRONTAL BOUNDARY WILL APPROACH FROM THE NORTH ON WEDNESDAY AND REMAIN IN THE VICINITY THROUGH THE END OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... SATELLITE IMAGERY INDICATING SOME CLEARING MAINLY ACROSS THE WESTERN ZONES WITH LOW STRATUS SLOWLY ERODING OVER THE EASTERN ZONES ATTM. COLD POOL ALOFT BEGINNING TO INTERACT WITH SURFACE HEATING AHEAD OF APPROACHING COLD FRONT CAUSING FEW SHOWERS TO DEVELOP ACROSS ZONE 1 ATTM. MODEL SOUNDINGS INDICATE CAPE VALUES INCREASING TO 500 TO 1000 J/KG MAINLY ACROSS THE NORTHERN ZONES THROUGH 18Z THEN DECREASING WITH THE FRONTAL PASSAGE THEREAFTER. EXPECT ACTIVITY TO INCREASE IN COVERAGE INTO THIS AFTERNOON. PREVIOUS GRID FORECAST LOOKS GOOD SO NO ADJUSTMENTS ARE NEEDED ATTM. && .SHORT TERM /TUESDAY THROUGH SATURDAY/... LOW PRES WELL E OF THE FA BY 12Z TUE AND WILL START THE DAY W/ SOME SC SPCLY UP N AND A RATHER BRISK NW WND BUT SHOULD SEE CONDS IMPROVE THRU THE DAY AS HGH PRES RDG RAPIDLY BUILDS INTO THE FA. HGH PRES PROGGED TO REMAIN IN CONTROL THRU TUE NGT AND INTO WED AND THEN THINGS ARE A BIT LESS CLEAR...GFS CONTS TO BRING A BACK DOOR FRONT INTO THE NRN HALF OF THE FA WED AFT WHILE THE NAM HOLDS IT UP UNTIL WED NGT. FOR NOW...PER THESE CONTG MODEL DIFFS...HELD THE SAME COURSE W/ NO MAJOR CHANGES MADE FOR WED AND BEYOND. && .LONG TERM /SATURDAY NIGHT THROUGH SUNDAY/... WE FOLLOWED HPC SET OF GUIDE THIS SECTION WHICH CONTINUES TO MAINTAIN FRONTAL BOUNDARY IN OUR VCNTY AND A CHANCE OF SHWRS. && .AVIATION /15Z MONDAY THROUGH FRIDAY/... NEAR TERM: MVFR CONDITIONS EARLY TODAY WILL IMPROVE TO VFR AS DRIER AIR MOVES IN. VFR CONDITIONS ARE EXPECTED TONIGHT. SHORT TERM: VFR CONDS TUE INTO WED THEN LOW CONFIDENCE THE REMAINDER OF THE PERIOD PER CONTG MODEL DIFFS W/ THE TIMING STRENGTH OF THE BACKDOOR FRONT AND OTHER PSBL WAVES OF LOW PRES THAT MAY TRACK ALONG THIS FRONT AND AFFECT OUR REGION FROM TIME TO TIME THROUGH FRI. && .MARINE... NEAR TERM: FOR THE CWF HAVE ADJUSTED WIND FIELD DOWN AS PER LATEST OBERSEVATIONS. HAVE USED THE RUC MODEL WHICH APPEARS TO BE HANDLING THE SURFACE WIND FIELD THE BEST. ADJUSTEMNTS MADE TO THE FIRST AND BEGINNING OF THE SECOND PERIOD ON THE UPDATE. SHORT TERM: NO MAJOR HEADLINES ANTICIPATED IN THE SHORT TERM ATTM. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...NONE. && $$ NEAR TERM...BLOOMER/FITZSIMMONS SHORT TERM...KHW LONG TERM...STUREY AVIATION...BLOOMER/FITZSIMMONS MARINE...BLOOMER/FITZSIMMONS/KHW me AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1030 PM EDT TUE MAY 29 2007 .UPDATE... DIURNALLY DRIVEN CONVECTION GENERALLY ON WANE OVER CWFA PER RADAR LOOP AND WARMING CLOUD TOPS OR IR SATELLITE IMAGERY. WILL KEEP IN ISOLD SHRA AND TSRA OVERNIGHT FOR GOG-ONT COUNTIES AND OVER WRN LAKE SUPERIOR IN CLOSE PROXIMITY TO HIGHER THETA-E AIR AND CONVERGENCE ALONG WEAK SFC TROF. OTHERWISE...EXPECT CONVECTION TO END OVER REST OF WEST HALF OF UPR MI WITH LACK OF FORCING OVERNIGHT AND LOSS OF SB INSTABILITY. && .SHORT TERM (TONIGHT/WED)... MAIN FCST ISSUE IS SHRA/TSRA POTENTIAL AND COVERAGE. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A SHARP TROF OVER THE ROCKIES WITH DOWNSTREAM RIDGE EXTENDING FROM THE SE STATES N TO MI. A VERY WEAK SHORTWAVE WAS OVER ERN UPPER MI. THIS WAVE PRODUCED A FEW SHRA/ISOLD TSRA OVER THE DOOR PENINSULA AND ACROSS NRN LAKE MICHIGAN TODAY. TO THE W...ANOTHER WEAK SHORTWAVE LIFTING NE THRU MN HAS PROBABLY PROVIDED SOME ASSISTANCE TO SHRA/ISOLD TSRA DEVELOPING OVER WRN UPPER MI WHERE MLCAPES ARE NEARING 1000J/KG. VIS SATELLITE IMAGERY INDICATES ERN FCST AREA REMAINS MORE STABLE DUE TO FLOW OFF LAKE MICHIGAN AS CU FIELD HAS SET UP W OF A LINE FROM SHOT POINT TO MENOMINEE. DEEP SRLY FLOW CONTINUES TO BRING MOISTURE N INTO THE UPPER MISSISSIPPI VALLEY/WRN GREAT LAKES. PRECIPITABLE WATER AT KMPX/KGRB WAS JUST UNDER 1.5 INCHES (JUST OVER 200PCT OF NORMAL) AT 12Z. SHARP TROF OVER THE ROCKIES WILL CLOSE OFF INTO A MIDLEVEL LOW CENTERED OVER NEBRASKA/SD BY LATE WED AFTN. SO...PROGRESSION OF PATTERN WILL SLOW TO A CRAWL...LEAVING UPPER MI IN DEEP LAYERED SSW FLOW JUST W OF THE MIDLEVEL RIDGE AXIS. PINNING DOWN WHEN AND WHERE PCPN WILL OCCUR IS SOMEWHAT UNCERTAIN...DEPENDING ON TIMING/LOCATION OF MINOR SHORTWAVES IN THE FLOW. BASED ON AFTN WATER VAPOR IMAGERY...THERE DOESN`T APPEAR TO BE ANY SHORTWAVES UPSTREAM HEADED FOR UPPER MI TONIGHT...AND WITH NO WAA OCCURRING...THERE WILL BE NO ISENTROPIC ASCENT TO AID PCPN DEVELOPMENT (WAA/ISENTROPIC ZONE WILL BE WELL N OF LAKE SUPERIOR) SO...ONCE INSTABILITY DIMINISHES THIS EVENING...THERE SHOULD BE LITTLE/NO POTENTIAL FOR PCPN OVERNIGHT. WILL THUS CARRY CHC POPS THIS EVENING OVER THE W HALF OF UPPER MI AND THEN GO DRY OVERNIGHT. IT WILL BE A MILD NIGHT AS MOIST AIRMASS LIMITS TEMP FALL. MOST LOCATIONS AWAY FROM LAKE MICHIGAN SHOULD FALL NO LWR THAN THE LWR 60S. WED SHOULD BE A SIMILAR SETUP TO TODAY. THERE ARE INDICATIONS THAT A WEAK SHORTWAVE WILL PASS ACROSS OR NEAR WRN UPPER MI. OTHERWISE... BUILDING INSTABILITY DURING THE DAY WILL BE THE MAIN FACTOR FOR ANY SHRA/TSRA DEVELOPMENT. GFS LOWERS MIXED LAYER DWPTS WED COMPARED TO TODAY WITH READINGS FALLING INTO THE LOW/MID 50S. AS RESULT...MLCAPE RISES NO HIGHER THAN 300-400J/KG. IF DWPTS FALL TOWARD WHAT THE GFS MOS GUIDANCE INDICATES FOR SFC DWPTS...SBCAPE WILL BE EVEN LOWER. NAM IS MORE MOIST AS IT USUALLY IS...BUT ITS MIXED LAYER DWPTS GENERALLY IN THE UPPER 50S MAY BE MORE REASONABLE BASED ON READINGS UPSTREAM TODAY. THIS RESULTS IN MLCAPE RISING POTENTIALLY TO NEAR 1000J/KG. WITH DEEP LAYER SHEAR OF NO MORE THAN 20-25KT...DO NOT ANTICIPATE ANY SVR STORMS. WILL CARRY CHC POPS DURING THE AFTN HRS AGAIN ONLY OVER THE W HALF OF UPPER MI WHERE THERE WON`T BE ANY MODIFICATION OF AIRMASS BY MARINE LAYER OFF LAKE MICHIGAN. SPEAKING OF THE MARINE LAYER...BOUNDARY LAYER WINDS WILL BE LIGHTER WED... SUGGESTING LAKE BREEZES COULD DEVELOP W NEAR LAKE SUPERIOR AS THE RUC13 INDICATES. THIS WOULD PROVIDE A FOCUS FOR CONVECTIVE DEVELOPMENT. WHILE NOT EXPECTED AT THE MOMENT...LAKE SUPERIOR LAKE BREEZE COULD ALSO DEVELOP E OF MARQUETTE...PROVIDING A FOCUS FOR CONVECTION. SHOULD THAT OCCUR...THERE MAY BE SOME SHRA/TSRA OVER THE OVER THE NE FCST AREA. && .LONG TERM. (WEDNESDAY NIGHT THROUGH TUESDAY)... AS WE BEGIN WEDNESDAY NIGHT...THE SURFACE LOW IS EXPECTED TO BE OVER THE DAKOTAS AND WEST CENTRAL MINNESOTA. A WEAK FRONTAL BOUNDARY/STATIONARY FRONT SHOULD BE SITUATED ACROSS THE EXTREME NORTHERN PORTIONS OF THE CWA...ACTING AS A GOOD FOCUS FOR SHOWER AND THUNDERSTORM ACTIVITY. LITTLE IN THE WAY OF EASTWARD PROGRESSION IS FIGURED FROM THE SURFACE LOW. STILL...IT SHOULD BE CENTERED OVER NORTHERN MINNESOTA BY SATURDAY MORNING...PROGRESSING OVER LAKE SUPERIOR SATURDAY AFTERNOON...WITH THE COLD FRONT JUST TO OUR EAST BY 00Z SUNDAY ACCORDING TO THE GFS. FURTHER OUT IN THE LAND OF EXTENDED FORECASTING...THE 00Z RUN OF THE ECMWF WAS GENERALLY PREFERRED. THE 21Z NAM WAS THROWN OUT OF THE MIX SINCE IS WAS QUICKER TO BRING THINGS ACROSS OUR REGION...AND THE PREFERRED ECMWF ACTUALLY SLOWED DOWN. WHEN COMPARING THE ECMWF TO THE GFS...HAVING THE COLD FRONT JUST TO OUR EAST BY 00Z SUNDAY MAY STILL BE TOO QUICK...WITH THE 12Z GFS SEEMING TO BE STILL ABOUT 9 HOURS QUICKER THAN THE PREFERRED 00Z ECMWF. AS FOR CHANGES TO OUR ONGOING FORECAST...INCREASED MAX TEMPERATURES FOR THURSDAY SLIGHTLY...MOVING AWAY FROM THE QUICKER NAM SOLUTION. WITH THE CONTINUATION OF RELATIVELY HIGH DEW POINTS...THE MENTION OF FOG MAY NEED TO BE CONTINUED FURTHER OUT INTO THE FORECAST PERIOD...BUT WILL MAKE NO ADJUSTMENTS TO THIS AS OF YET. FRIDAY NIGHT INTO SATURDAY MORNING...WOULD HAVE INCREASED TEMPERATURES BY 5 DEGREES PER HPC GUIDANCE...BUT INSTEAD TOOK A MIDDLE OF THE ROAD APPROACH FOR THE TIME BEING...BLENDING WITH THE CURRENT ONGOING FORECAST. HAVE ALSO GONE AHEAD AND INCREASED SUNDAY NIGHT/MONDAY MORNING LOWS BY ABOUT 5 DEGREES GIVEN PLENTY OF CLOUD COVER EXPECTED. WITH THE 500MB TROUGH IN NO HURRY TO EXIT THE NORTHERN GREAT LAKES REGION...IT WILL BE DIFFICULT TO TAKE THE MENTION OF SHOWERS OR MAYBE EVEN SOME AFTERNOON THUNDERSTORMS OUT OF THE FORECAST. BOTH THE GFS AND ECMWF HAVE GENERAL TROUGHINESS OVER THE CWA THROUGH AT LEAST MONDAY...WITH THE GFS TRYING TO DIG EVEN FURTHER SOUTH...PRODUCING A CUTOFF LOW OVER THE MID MISSISSIPPI VALLEY BY 18Z MONDAY. SO...NO PROLONGED PERIOD OF DRY WEATHER IS FIGURED OVER OVER THE NEXT WEEK. && .MARINE (FOR 4 PM ISSUANCE OF LAKE SUPERIOR FCST)... EXPECT HIGH PRES OVER LAKE ONTARIO TO DRIFT OFF THE MID ATLANTIC COAST ON THU WHILE LOW PRES ALONG ND/MN BORDER JUST MEANDERS SLOWLY TO THE E. THIS LOW WILL GRADUALLY PUSH INTO THE UPPER GREAT LAKES THROUGH THE WEEKEND AND WEAKEN. SRLY WINDS WILL REMAIN UP ON THE E HALF OF LAKE SUPERIOR TONIGHT...ESPECIALLY ON HIGHER OBSERVING PLATFORMS WHERE 20-25KT WINDS WILL BE COMMON. FARTHER DOWN IN THE STABLE MARINE LAYER...WINDS SHOULD GENERALLY BE BTWN 10-15KT AT THE BUOY PLATFORMS. OVER THE W HALF OF THE LAKE...AS IS TYPICAL IN SRLY WIND REGIMES OVER A VERY STABLE MARINE LAYER...WINDS WILL AGAIN REMAIN MORE BACKED TO AN E OR NE DIRECTION NEAR THE MN SHORELINE. OTHERWISE...LIGHTER SE TO S WINDS WILL PREVAIL THAN OVER THE E HALF OF THE LAKE TONIGHT. FOR THE MOST PART...GENERALLY LIGHT WINDS WILL PREVAIL INTO THE UPCOMING WEEKEND AS WEAK PRES GRADIENT WILL BE OVER THE AREA. FOG SHOULD BECOME AN ISSUE LATER TONIGHT THRU AT LEAST THU EVENING ONCE SOME RAINFALL OCCURS OVER THE LAKE AND MOISTENS THE CHILLY MARINE LAYER UNDER SHARP INVERSION. && .AVIATION (FOR 00Z TAFS)... EXPECT DIURNAL SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS TO DISSIPATE BY LATE EVENING WITH LOSS OF HEATING. VFR CONDITIONS CAN BE EXPECTED OVERNIGHT. LOOK FOR ANOTHER ROUND OF BKN CLOUD COVER AND POSSIBLE SHOWERS AND THUNDERSTORMS WED AFTERNOON. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...JV SHORT TERM/MARINE...ROLFSON LONG TERM...KF AVIATION...JV mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 726 PM EDT TUE MAY 29 2007 .SHORT TERM (TONIGHT/WED)... MAIN FCST ISSUE IS SHRA/TSRA POTENTIAL AND COVERAGE. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A SHARP TROF OVER THE ROCKIES WITH DOWNSTREAM RIDGE EXTENDING FROM THE SE STATES N TO MI. A VERY WEAK SHORTWAVE WAS OVER ERN UPPER MI. THIS WAVE PRODUCED A FEW SHRA/ISOLD TSRA OVER THE DOOR PENINSULA AND ACROSS NRN LAKE MICHIGAN TODAY. TO THE W...ANOTHER WEAK SHORTWAVE LIFTING NE THRU MN HAS PROBABLY PROVIDED SOME ASSISTANCE TO SHRA/ISOLD TSRA DEVELOPING OVER WRN UPPER MI WHERE MLCAPES ARE NEARING 1000J/KG. VIS SATELLITE IMAGERY INDICATES ERN FCST AREA REMAINS MORE STABLE DUE TO FLOW OFF LAKE MICHIGAN AS CU FIELD HAS SET UP W OF A LINE FROM SHOT POINT TO MENOMINEE. DEEP SRLY FLOW CONTINUES TO BRING MOISTURE N INTO THE UPPER MISSISSIPPI VALLEY/WRN GREAT LAKES. PRECIPITABLE WATER AT KMPX/KGRB WAS JUST UNDER 1.5 INCHES (JUST OVER 200PCT OF NORMAL) AT 12Z. SHARP TROF OVER THE ROCKIES WILL CLOSE OFF INTO A MIDLEVEL LOW CENTERED OVER NEBRASKA/SD BY LATE WED AFTN. SO...PROGRESSION OF PATTERN WILL SLOW TO A CRAWL...LEAVING UPPER MI IN DEEP LAYERED SSW FLOW JUST W OF THE MIDLEVEL RIDGE AXIS. PINNING DOWN WHEN AND WHERE PCPN WILL OCCUR IS SOMEWHAT UNCERTAIN...DEPENDING ON TIMING/LOCATION OF MINOR SHORTWAVES IN THE FLOW. BASED ON AFTN WATER VAPOR IMAGERY...THERE DOESN`T APPEAR TO BE ANY SHORTWAVES UPSTREAM HEADED FOR UPPER MI TONIGHT...AND WITH NO WAA OCCURRING...THERE WILL BE NO ISENTROPIC ASCENT TO AID PCPN DEVELOPMENT (WAA/ISENTROPIC ZONE WILL BE WELL N OF LAKE SUPERIOR) SO...ONCE INSTABILITY DIMINISHES THIS EVENING...THERE SHOULD BE LITTLE/NO POTENTIAL FOR PCPN OVERNIGHT. WILL THUS CARRY CHC POPS THIS EVENING OVER THE W HALF OF UPPER MI AND THEN GO DRY OVERNIGHT. IT WILL BE A MILD NIGHT AS MOIST AIRMASS LIMITS TEMP FALL. MOST LOCATIONS AWAY FROM LAKE MICHIGAN SHOULD FALL NO LWR THAN THE LWR 60S. WED SHOULD BE A SIMILAR SETUP TO TODAY. THERE ARE INDICATIONS THAT A WEAK SHORTWAVE WILL PASS ACROSS OR NEAR WRN UPPER MI. OTHERWISE... BUILDING INSTABILITY DURING THE DAY WILL BE THE MAIN FACTOR FOR ANY SHRA/TSRA DEVELOPMENT. GFS LOWERS MIXED LAYER DWPTS WED COMPARED TO TODAY WITH READINGS FALLING INTO THE LOW/MID 50S. AS RESULT...MLCAPE RISES NO HIGHER THAN 300-400J/KG. IF DWPTS FALL TOWARD WHAT THE GFS MOS GUIDANCE INDICATES FOR SFC DWPTS...SBCAPE WILL BE EVEN LOWER. NAM IS MORE MOIST AS IT USUALLY IS...BUT ITS MIXED LAYER DWPTS GENERALLY IN THE UPPER 50S MAY BE MORE REASONABLE BASED ON READINGS UPSTREAM TODAY. THIS RESULTS IN MLCAPE RISING POTENTIALLY TO NEAR 1000J/KG. WITH DEEP LAYER SHEAR OF NO MORE THAN 20-25KT...DO NOT ANTICIPATE ANY SVR STORMS. WILL CARRY CHC POPS DURING THE AFTN HRS AGAIN ONLY OVER THE W HALF OF UPPER MI WHERE THERE WON`T BE ANY MODIFICATION OF AIRMASS BY MARINE LAYER OFF LAKE MICHIGAN. SPEAKING OF THE MARINE LAYER...BOUNDARY LAYER WINDS WILL BE LIGHTER WED... SUGGESTING LAKE BREEZES COULD DEVELOP W NEAR LAKE SUPERIOR AS THE RUC13 INDICATES. THIS WOULD PROVIDE A FOCUS FOR CONVECTIVE DEVELOPMENT. WHILE NOT EXPECTED AT THE MOMENT...LAKE SUPERIOR LAKE BREEZE COULD ALSO DEVELOP E OF MARQUETTE...PROVIDING A FOCUS FOR CONVECTION. SHOULD THAT OCCUR...THERE MAY BE SOME SHRA/TSRA OVER THE OVER THE NE FCST AREA. && .LONG TERM. (WEDNESDAY NIGHT THROUGH TUESDAY)... AS WE BEGIN WEDNESDAY NIGHT...THE SURFACE LOW IS EXPECTED TO BE OVER THE DAKOTAS AND WEST CENTRAL MINNESOTA. A WEAK FRONTAL BOUNDARY/STATIONARY FRONT SHOULD BE SITUATED ACROSS THE EXTREME NORTHERN PORTIONS OF THE CWA...ACTING AS A GOOD FOCUS FOR SHOWER AND THUNDERSTORM ACTIVITY. LITTLE IN THE WAY OF EASTWARD PROGRESSION IS FIGURED FROM THE SURFACE LOW. STILL...IT SHOULD BE CENTERED OVER NORTHERN MINNESOTA BY SATURDAY MORNING...PROGRESSING OVER LAKE SUPERIOR SATURDAY AFTERNOON...WITH THE COLD FRONT JUST TO OUR EAST BY 00Z SUNDAY ACCORDING TO THE GFS. FURTHER OUT IN THE LAND OF EXTENDED FORECASTING...THE 00Z RUN OF THE ECMWF WAS GENERALLY PREFERRED. THE 21Z NAM WAS THROWN OUT OF THE MIX SINCE IS WAS QUICKER TO BRING THINGS ACROSS OUR REGION...AND THE PREFERRED ECMWF ACTUALLY SLOWED DOWN. WHEN COMPARING THE ECMWF TO THE GFS...HAVING THE COLD FRONT JUST TO OUR EAST BY 00Z SUNDAY MAY STILL BE TOO QUICK...WITH THE 12Z GFS SEEMING TO BE STILL ABOUT 9 HOURS QUICKER THAN THE PREFERRED 00Z ECMWF. AS FOR CHANGES TO OUR ONGOING FORECAST...INCREASED MAX TEMPERATURES FOR THURSDAY SLIGHTLY...MOVING AWAY FROM THE QUICKER NAM SOLUTION. WITH THE CONTINUATION OF RELATIVELY HIGH DEW POINTS...THE MENTION OF FOG MAY NEED TO BE CONTINUED FURTHER OUT INTO THE FORECAST PERIOD...BUT WILL MAKE NO ADJUSTMENTS TO THIS AS OF YET. FRIDAY NIGHT INTO SATURDAY MORNING...WOULD HAVE INCREASED TEMPERATURES BY 5 DEGREES PER HPC GUIDANCE...BUT INSTEAD TOOK A MIDDLE OF THE ROAD APPROACH FOR THE TIME BEING...BLENDING WITH THE CURRENT ONGOING FORECAST. HAVE ALSO GONE AHEAD AND INCREASED SUNDAY NIGHT/MONDAY MORNING LOWS BY ABOUT 5 DEGREES GIVEN PLENTY OF CLOUD COVER EXPECTED. WITH THE 500MB TROUGH IN NO HURRY TO EXIT THE NORTHERN GREAT LAKES REGION...IT WILL BE DIFFICULT TO TAKE THE MENTION OF SHOWERS OR MAYBE EVEN SOME AFTERNOON THUNDERSTORMS OUT OF THE FORECAST. BOTH THE GFS AND ECMWF HAVE GENERAL TROUGHINESS OVER THE CWA THROUGH AT LEAST MONDAY...WITH THE GFS TRYING TO DIG EVEN FURTHER SOUTH...PRODUCING A CUTOFF LOW OVER THE MID MISSISSIPPI VALLEY BY 18Z MONDAY. SO...NO PROLONGED PERIOD OF DRY WEATHER IS FIGURED OVER OVER THE NEXT WEEK. && .MARINE (FOR 4 PM ISSUANCE OF LAKE SUPERIOR FCST)... EXPECT HIGH PRES OVER LAKE ONTARIO TO DRIFT OFF THE MID ATLANTIC COAST ON THU WHILE LOW PRES ALONG ND/MN BORDER JUST MEANDERS SLOWLY TO THE E. THIS LOW WILL GRADUALLY PUSH INTO THE UPPER GREAT LAKES THROUGH THE WEEKEND AND WEAKEN. SRLY WINDS WILL REMAIN UP ON THE E HALF OF LAKE SUPERIOR TONIGHT...ESPECIALLY ON HIGHER OBSERVING PLATFORMS WHERE 20-25KT WINDS WILL BE COMMON. FARTHER DOWN IN THE STABLE MARINE LAYER...WINDS SHOULD GENERALLY BE BTWN 10-15KT AT THE BUOY PLATFORMS. OVER THE W HALF OF THE LAKE...AS IS TYPICAL IN SRLY WIND REGIMES OVER A VERY STABLE MARINE LAYER...WINDS WILL AGAIN REMAIN MORE BACKED TO AN E OR NE DIRECTION NEAR THE MN SHORELINE. OTHERWISE...LIGHTER SE TO S WINDS WILL PREVAIL THAN OVER THE E HALF OF THE LAKE TONIGHT. FOR THE MOST PART...GENERALLY LIGHT WINDS WILL PREVAIL INTO THE UPCOMING WEEKEND AS WEAK PRES GRADIENT WILL BE OVER THE AREA. FOG SHOULD BECOME AN ISSUE LATER TONIGHT THRU AT LEAST THU EVENING ONCE SOME RAINFALL OCCURS OVER THE LAKE AND MOISTENS THE CHILLY MARINE LAYER UNDER SHARP INVERSION. && .AVIATION (FOR 00Z TAFS)... EXPECT DIURNAL SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS TO DISSIPATE BY LATE EVENING WITH LOSS OF HEATING. VFR CONDITIONS CAN BE EXPECTED OVERNIGHT. LOOK FOR ANOTHER ROUND OF BKN CLOUD COVER AND POSSIBLE SHOWERS AND THUNDERSTORMS WED AFTERNOON. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM/MARINE...ROLFSON LONG TERM...KF AVIATION...JV mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 156 PM EDT TUE MAY 29 2007 .AVIATION (FOR 18Z TAFS)... ISOLATED SHOWERS ARE DEVELOPING OVER NORTHERN WI AND WESTERN UPPER MI. MAIN CHALLENGE WITH FCST IS TIMING/COVERAGE OF PCPN AND THE CHANCE OF THUNDER. LEFT THUNDER OUT OF FCST FOR THIS AFTERNOON DUE TO THE UNCERTAINTY OF THE THUNDER OCCURRING AT THE TAF SITES...BUT INCLUDED CB CLOUD TYPE TO REFLECT CONVECTION. USED TEMPO GROUPS TO REFLECT THE SCATTERED TYPE OF PCPN. EXPECT PCPN TO DISSIPATE WITH COOLING TONIGHT. ANOTHER ROUND OF BKN CLOUDS AND POSSIBLE PCPN WILL MAKE ITS WAY INTO THE AREA TOWARD THE END OF THE TAF PERIOD. && .UPDATE (ISSUED AT 1105 AM)... MAIN FCST ISSUE THIS AFTN IS SHRA/TSRA POTENTIAL. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A TROF OVER THE ROCKIES WITH DOWNSTREAM RIDGE EXTENDING FROM THE SE STATES N TO MI. A VERY WEAK SHORTWAVE WAS OVER NE WI/CNTRL UPPER MI. SO FAR...WAVE HAS ONLY PRODUCED SOME -SHRA/ISOLD TSRA OVER THE DOOR PENINSULA AND JUST E OF THERE. TO THE W...ANOTHER WEAK SHORTWAVE LIFTING NE THRU MN WAS PRODUCING A FEW -SHRA/ISOLD TSRA...MAINLY W OF KDLH...BUT SOME SHRA HAVE DEVELOPED EWD TOWARD THE KEWEENAW RECENTLY. VERY WEAK SHORTWAVE OVER NE WI IS HEADED MORE ERLY AROUND RIDGE AXIS WHILE SHORTWAVE IN MN IS HEADING MORE NRLY. SO...IT DOES NOT APPEAR ANY SHORTWAVES WILL DIRECTLY AFFECT THE FCST AREA THIS AFTN TO PROVIDE A FOCUS FOR WIDESPREAD SHRA/TSRA. SHORTWAVES WILL BE CLOSE ENOUGH THOUGH TO AID SHRA DEVELOPMENT OVER THE FAR W THIS AFTN AND POSSIBLY OVER THE SE FCST AREA FOR THE NEXT FEW HRS. OTHERWISE... INSTABILITY WILL BUILD AS HEATING CONTINUES...LEADING TO THE POTENTIAL OF SCT SHRA/TSRA...BUT THERE ARE NO WELL-DEFINED BOUNDARIES TO PROVIDE A STRONG FOCUS. MODIFIED KGRB SOUNDING FOR SFC T/TD OF 80/58F YIELDS SBCAPE OF ABOUT 400J/KG WHILE 80/60F YIELDS NEARLY 800J/KG. WITH LIMITED SBCAPE AND DEEP LAYER SHEAR ON THE ORDER OF 20-25KT...DO NOT ANTICIPATE ANY SVR STORMS THIS AFTN. DECENT SRLY FLOW OFF LAKE MICHIGAN SHOULD KEEP THE ERN FCST AREA STABILIZED SUFFICIENTLY TO PRECLUDE ANY SHRA/TSRA DEVELOPMENT AFTER THE POSSIBILITY OF ISOLD SHRA WITH SHORTWAVE BRUSHING THE SE OVER THE NEXT FEW HRS. 12Z RUC FCST SOUNDINGS SUPPORT A DRY FCST THERE. && .PREV DISCUSSION (ISSUED AT 344 AM EDT)... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND TONIGHT. WATER VAPOR AND RUC/NAM SHOWING A BROAD RIDGE FROM EASTERN MANITOBA TO WESTERN QUEBEC...INCLUDING OVER MUCH OF THE UPPER GREAT LAKES. TO THE WEST A CLOSED LOW IS OVER SOUTHERN SASKATCHEWAN WITH AN ACCOMPANYING TROUGH EXTENDING SOUTHWEST INTO WESTERN MONTANA. WEAK SHORTWAVES ARE TRAVELING THROUGH THE RIDGE AND ARE OVER SOUTHERN MINNESOTA... CENTRAL SOUTH DAKOTA AND IN SASKATCHEWAN. SURFACE ANALYSIS DEPICTS A 1026MB HIGH OVER THE LOWER GREAT LAKES AND A DEEP LOW OVER MIDDLE HIGH PLAINS. ANOTHER LOW IS OVER SOUTHERN MANITOBA. A WEAK FRONTAL SYSTEM STRETCHES EAST TO WEST ACROSS SOUTHERN CANADA THROUGH THIS LOW...WHILE A WARM FRONT EXTENDS EAST THROUGH NORTHEAST WISCONSIN AND THE UPPER GREAT LAKES. ALSO A COLD FRONT LINKS THE MANITOBA LOW WITH THE EASTERN COLORADO LOW. A HIGH PRESSURE CENTER IS BUILDING OVER THE THE PACIFIC NORTHWEST. NUMEROUS THUNDERSTORMS ARE FIRING NORTH OF THE MINNESOTA ARROWHEAD IN WESTERN ONTARIO...AND OVER CENTRAL DAKOTAS AND NEBRASKA IN ASSOCIATE WITH THE FRONTAL. NAM/GFS SOLUTIONS ARE IN GOOD AGREE FOR TODAY AND TONIGHT. THE UPPER GREAT LAKES RIDGE WILL BECOME MORE FOCUSED...WHILE THE LOW OVER SASKATCHEWAN DIGS INTO EASTERN MONTANA. ONE OF THE WEAK SHORTWAVES OVER SOUTH DAKOTA WILL SWEEP INTO THE WESTERN U.P. WHILE THE REST MOVES INTO WESTERN MINNESOTA. 850-500MB Q-VECTOR ANALYSIS SUGGEST AND INCREASE IN CONVERGENCE THIS AFTERNOON OVER THE WESTERN U.P. THE SURFACE HIGH OVER THE LOWER GREAT LAKES WILL SHIFT TO THE EAST COAST....WHILE THE WEST END OF THE WARM FRONT WASHES OUT. THE SURFACE LOW OVER MANITOBA WILL MOVE INTO NORTHWEST MINNESOTA DRAGGING THE COLD FRONT INTO CENTRAL MINNESOTA. ANTI-CYCLONIC FLOW AROUND THE EAST COAST HIGH WILL DRAW WARM GULF MOISTURE INTO THE THE UPPER MISSISSIPPI RIVER VALLEY AND THE UPPER GREAT LAKES. MUCAPE WILL INCREASE TO OVER 1000J/KG OVER THE WESTERN U.P. THEREFORE... ISENTROPIC ASCENT AHEAD OF THE COLD FRONT WILL TRIGGER THUNDERSTORMS AND SHOWERS OVER WISCONSIN AND WESTERN U.P. IN THE AREA OF GREATEST INSTABILITY THIS AFTERNOON...WHICH WILL BE MAINLY WEST OF US-41 FROM MARQUETTE TO ESCANABA. THE MID LEVEL LOW OVER THE MONTANA WILL STAY MAINLY OVER THE NORTHERN HIGH PLAINS TONIGHT. THE BROAD HIGH WILL CONTINUE TO BLANKET THE EASTERN THIRD OF THE CONUS. THE SURFACE LOW WILL BECOME STAGNANT OVER WESTERN MINNESOTA AND EASTERN NEBRASKA. A STATIONARY FRONT REMAINS OVER CENTRAL ONTARIO JUST NORTH OF LAKE SUPERIOR...AND OVER MINNESOTA AND EASTERN NEBRASKA. MORE WARM MOIST GULF AIR WILL CONTINUE TO BE DRAWN INTO WISCONSIN AND INTO CENTRAL ONTARIO. MODELS SHOW WEAK ISENTROPIC ASCENT OVER THE AREA. MOST OF THE Q-VECTOR CONVERGENCE WILL REMAIN NORTH OF LAKE SUPERIOR. MUCAPE VALUES SHOULD DROP OFF TO NEAR ZERO OVERNIGHT. THERE WILL BE SOME WEAK DIVERGENCE ALOFT. THUS INSTABILITY WILL BECOME MARGINAL OVERNIGHT...AND ISENTROPIC ASCENT WILL BE BARELY ENOUGH AHEAD OF THE FRONTAL SYSTEM TO TRIGGER SOME SHOWERS AND THUNDERSTORMS...SO WILL KEEP A MENTION GOING...HOWEVER...MOST OF THE THUNDERSTORM ACTIVITY WILL BE WEST AND NORTH OF THE FORECAST AREA. ON WEDNESDAY...THE GFS STARTS TO HOLD THE SURFACE LOW WEST OVER NORTHEAST SOUTH DAKOTA WHILE THE NAM/GEM/WRF FAVOR A CENTRAL MINNESOTA POSITION. THE UKMET IS A COMPROMISED SOLUTION. MODELS FAVOR THE STRONG WINDS ALOFT...SO WILL FAVOR THE MORE PROGRESS SOLUTIONS. THE MID LEVEL HIGH CONTINUES TO SLIDE DOWN THE ATLANTIC COAST WHILE THE RIDGE REMAINS STRETCHES ACROSS THE THE FORECAST AREA. MEANWHILE...THE MONTANA LOW WILL SPIN INTO SOUTHEAST MONTANA. SHORTWAVE SWEEPING THROUGH THE BASE OF THIS LOW WILL SAIL ACROSS THE FORECAST AREA. THE SURFACE LOW WILL BECOME FOCUSED OVER CENTRAL MINNESOTA WITH THE CANADIAN COLD FRONT EXTENDING ACROSS NORTHERN LAKE SUPERIOR...AND THE PLAINS COLD FRONT DRAPED SOUTHWEST INTO THE EASTERN KANSAS. DEEP MOISTURE CONTINUES TO BE DRAWN INTO THE FORECAST AREA FEEDING A CHANCE OF SHOWERS AND THUNDERSTORMS ON WEDNESDAY. THE MID LEVEL LOW OVER MONTANA WILL SLIP INTO NORTH CENTRAL SOUTH DAKOTA WHILE THE RIDGE REMAINS OVER THE FORECAST AREA WEDNESDAY NIGHT. WEAK SHORTWAVES WILL TRACK THROUGH THE RIDGE OVER THE FORECAST AREA. THE SURFACE LOW WILL LIFT INTO NORTHWEST MINNESOTA DRAGGING THE COLD FRONT INTO CENTRAL MINNESOTA. THE CANADIAN FRONTAL SYSTEM WILL REMAIN STATIONARY OVER NORTHERN LAKE SUPERIOR. ISENTROPIC ASCENT AND SHORTWAVE ENERGY WILL CONTINUE TO GENERATE A CHANCE OF SOME SHOWERS AND THUNDERSTORMS. Q-VECTOR ANALYSIS SUGGEST THAT THE MOST UNSTABLE AIR WILL BE ALONG THE CANADIAN FRONTAL SYSTEM. THE MID LEVEL LOW WILL REMAIN NEARLY STATIONARY NEAR KBIS...WITH A NUMBER OF WEAK SHORTWAVES ROTATING AROUND THIS LOW ON THURSDAY AND THURSDAY NIGHT. THE SURFACE LOW WILL ALSO BE PULLED NORTHWEST TO THE NORTH SIDE OF THE MID LEVEL LOW AND MOVE INTO NORTH CENTRAL NORTH DAKOTA. THE CANADIAN FRONTAL SYSTEM WILL REMAIN OVER CENTRAL ONTARIO. A WEAK SHORTWAVE BEING EJECTED OUT AHEAD OF THE OF MID LEVEL LOW WILL ATTEMPT TO TRAVERSE THE FORECAST AREA GENERATING A CHANCE OF SHOWERS AND THUNDERSTORMS. AS THE LOW BACKS WEST...THE ISENTROPIC ASCENT WILL ALSO WEAKEN...BUT STILL APPEARS TO BE STRONG ENOUGH TO KEEP A CHANCE OF THUNDERSTORMS GOING ESPECIALLY COUPLED WITH AFTERNOON HEATING. GUIDANCE SHOWING SURFACE DEW POINTS WILL BE HIGH ENOUGH TO PRODUCE FOG OVER THE COOL WATERS OF LAKE SUPERIOR. THE MID LEVEL RIDGE WILL START TO BREAK DOWN ON FRIDAY ALLOWING THE MID LEVEL LOW TO TREK EAST TO NEAR KJMS. THE SURFACE LOW WILL LINE UP WITH THE MID LEVEL LOW ALLOWING THE PLAINS FRONTAL SYSTEM TO MOVE INTO WESTERN IOWA. THE CANADIAN FRONT SYSTEM WILL LIKEWISE REMAIN WEAK AND OVER THE NORTHERN LAKE SUPERIOR. SHOWERS AND THUNDERSTORMS WILL CONTINUE TO BE A REAL POSSIBILITY. CURRENT GRIDS LOOK OK FOR NOW. && .MARINE (FOR 4 AM ISSUANCE OF LAKE SUPERIOR FCST)... EXPECT HIGH PRES OVER LAKE ONTARIO TO DRIFT OFF THE MID ATLANTIC COAST ON THU WHILE A LOW PRES JUST S OF LAKE WINNIPEG THIS MORNING MEANDERS SLOWLY TO THE E. THIS LOW WILL GRADUALLY PUSH INTO THE UPPER GREAT LAKES THROUGH THE WEEKEND AND WEAKEN. WINDS OVER THE LK TDAY WL RESPOND TO LK BREEZE CIRCULATION TDAY AFT MOSTLY DECOUPLED NOCTURNAL LLJ WEAKENS. LLJ TNGT WL NOT BE AS STRG WITH LACK OF PRES FALL CENTER ACRS ONTARIO. OTRW...FOLLOWED CNDN MODEL PER NCEP PREFERENCE FOR WINDS THRU THE REST OF THE WEEK. THIS MODEL IS QUITE A BIT SLOWER TO PUSH SFC LO E THAN INDICATED BY PREVIOUS GUIDANCE. CNDN SOLN PROMISES A WEAK PRES GRADIENT...SO WINDS WL BE ON THE LGT SIDE AND RESPOND TO LK BREEZE CIRCULATIONS IN THE DAY. FOG SHOULD BECOME AN ISSUE TUE NIGHT THRU THU ONCE SOME RAINFALL OCCURS OVER THE LAKE AND MOISTENS THE CHILLY MARINE LYR UNDER SHARP INVRN. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...ROLFSON PREV DISCUSSION...DLG MARINE...KC AVIATION...MRC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 120 PM EDT TUE MAY 29 2007 .AVIATION...CLOUDS ARE BEGINNING TO CLEAR OVER THE AREA...EXPECTED TO STAY VFR THROUGH THE REMAINDER OF THE AFTERNOON. CU DEVELOPMENT WILL LEAD TO SCT CONDITIONS AROUND TVC AND PLN...BUT WARM ADVECTION CLOUDS WILL LEAD TO A SHORT PERIOD OF BKN AT APN. DIURNAL CU WILL DISSIPATE AT SUNSET...BUT MOISTURE STREAMING NW WILL CONTINUE TO PRODUCE SCT MID LEVEL CLOUD DECK OVERNIGHT. THIS MOISTURE WILL ALSO LOWER VISBYS AND HAZE TO MVFR LEVELS AROUND TVC AND PLN EARLY TOMORROW MORNING. MOISTURE MAY NOT MAKE IT TO APN AND DECIDED TO LEAVE LOWER VISBYS OUT OF TAFS. FOR TOMORROW...EXPECT ANY LOWER VISBYS TO MIX OUT DURING THE MORNING AND CONDITIONS TO RETURN TO VFR FOR THE REST OF THE TAF PERIOD. MPC/SSK && .UPDATE...ISSUED AT 1048 AM EDT TUE LOW AND MID LEVEL WAA AND MOISTURE FLUX WELL UNDERWAY ACROSS THE NORTHERN LAKES ON UPSTREAM SIDE OF HIGH PRESSURE CENTERED OVER WESTERN NEW YORK...AS EVIDENT BY BROKEN MID LEVEL CU/ALTOCU DECK WORKING NORTHEAST ACROSS THE AREA AND LOCAL PWAT JUMPING FROM 0.36 INCHES ON LAST NIGHTS 00Z SOUNDING TO 1.02 INCHES WITH THIS MORNINGS RELEASE. HOWEVER...AS IS OFTEN THE CASE...GFS/NAM-WRF MODEL GUIDANCE OVERDOING LOW LEVEL MOISTENING...WITH OBSERVED UPPER 40 TO LOW 50 DEWPOINTS SEVERAL DEGREES LOWER THAN MODEL PROGS. FORECAST CONCERNS FOR THE REMAINDER OF THE DAY CENTER ON AFTERNOON CONVECTIVE POTENTIAL AS DAYTIME HEATING WORKS ON INCREASING MOISTURE. NOT A WHOLE LOT TO HANG YOUR HAT ON AS FAR AS A FOCUS FOR CONVECTION THIS AFTERNOON WITH LACK OF SYNOPTIC SCALE SURFACE BOUNDARY AND SOUTHWEST FLOW 950MB WINDS RAMPING UP TO 15 TO 25 KNOTS SEVERELY LIMITING LAKE BREEZE POTENTIAL. IN ADDITION...WILL IGNORE OVER ZEALOUS NAM-WRF/GFS SURFACE INSTABILITY PROGS SHOWING 1500+ J/KG CAPE (PRIMARILY A FUNCTION OF OVER MOISTENING...WITH THESE MODELS SUGGESTING SURFACE DEWPOINTS REACHING THE LOW 60S BY LATER THIS AFTERNOON). TAKING MORE CONSERVATIVE LOW TO MID 50 DEWPOINTS FOR THE AFTERNOON (LATEST RUC GUIDANCE ALSO SHOWING DEWPOINTS IN THIS RANGE) INDICATES MEAN LAYER CAPE OF ONLY 100 J/KG OR SO. THIS SHOULD BE JUST ENOUGH INSTABILITY...COMBINED WITH ANY SUBTLE LAKE INDUCED WIND CHANGE OR ENHANCED SURFACE CONVERGENCE IN HIGHER TERRAIN LOCALS...TO KICK OFF AN ISOLATED SHOWER OR THUNDERSTORM. OTHERWISE...STILL EXPECTING TEMPERATURES TO TOP OFF IN THE MID 70S TO LOW 80S AS BOUNDARY LAYER MIXING HELPS SCOUR SOME OF THIS MORNINGS CLOUD DECK. OTHERWISE...REST OF FORECAST IN GREAT SHAPE WITH NO CHANGES WARRANTED. UPDATED GRIDS/ZONES/NEARSHORES OUT SHORTLY. MSB && .AVIATION...ISSUED AT 725 AM OW/MID CLOUD DECK WILL CONTINUE TO OVERSPREAD ALL 3 TAF SITES THIS MORNING...THOUGH CEILINGS ARE EXPECTED TO REMAIN VFR WITH BASES AROUND 4-5KFT AT THE LOWEST. SHOULD SEE THESE ON THE WANE BY LATE MORNING...THOUGH WITH MOISTURE FLOWING INTO THE REGION AND WARM AFTERNOON TEMPERATURES...CU/STRATOCU DECK WILL FILL IN BY EARLY AFTERNOON. AN OUTSIDE CHANCE AT AN ISOLATED SHOWER OR THUNDERSTORM ALSO EXISTS OVER THE ENTIRE AREA BY LATE AFTERNOON INTO EARLY EVENING...THOUGH POSSIBILITIES FAR TOO SMALL TO MAKE ANY MENTION IN THE TAFS. WINDS WILL PICK UP JUST A BIT BY AFTERNOON...GENERALLY AROUND 10-15 KNOTS AT THEIR HIGHEST....BEFORE SLACKENING ONCE AGAIN AFTER SUNSET. WITH HIGH DEW POINTS IN PLACE AND RELATIVELY LIGHT WINDS...WILL LIKELY SEE SOME REDUCTION IN VISIBILITIES OVERNIGHT WITH MIST/LIGHT FOG...SIMILAR TO WHAT IS OCCURRING UPSTREAM THIS MORNING. THUS HAVE INCLUDED A MENTION OF THIS POSSIBILITY...ALTHOUGH WITH SOME UNCERTAINTY ABOUT HOW HIGH DEW POINTS WILL END UP...HAVE KEPT VISIBILITIES IN VFR RANGE...THOUGH COULD EASILY BE MVFR. LAWRENCE && .PREV DISCUSSION... /ISSUED 337 AM EDT TUE MAY 29 2007/ DISCUSSION...A SEEMINGLY BROKEN RECORD FORECAST APPEARS ON TAP FOR MUCH IF NOT ALL OF THE WORK WEEK...AND POTENTIALLY HEADING INTO THE WEEKEND...WITH WARM AND HUMID CONDITIONS IN PLACE ALONG WITH OCCASIONAL CHANCES FOR CONVECTION. THE MAIN FORECAST CHALLENGES THROUGH THE NEXT 5 DAYS ARE JUST HOW WARM THINGS WILL GET EACH AFTERNOON...ALONG WITH TIMING/COVERAGE OF ALMOST DAILY CHANCES FOR CONVECTION. EARLY MORNING SUBJECTIVE ANALYSIS PLACES AN ELONGATED BUT FAIRLY WEAK (1024MB) SURFACE RIDGE OVER THE EASTERN GREAT LAKES AND INTO THE NORTHEAST...WITH A STATIONARY FRONT DRAPED OVER THE NORTHERN OHIO VALLEY BEFORE BECOMING A WARM FRONT OVER THE MID MISSISSIPPI VALLEY IN DEVELOPING RETURN FLOW/WARM ADVECTION REGIME. ALOFT...RATHER IMPRESSIVE SHORTWAVE PER EVENING WATER VAPOR PICS NOTED DIVING INTO EASTERN IDAHO...WITH HEIGHT FALLS EMERGING ONTO THE WESTERN HIGH PLAINS DRIVING SURFACE CYCLOGENESIS OVER THIS REGION...BUT AIDING IN DOWNSTREAM HEIGHT RISES OVER MUCH OF THE EASTERN CONUS AS UPPER RIDGE BEGINS TO BUILD. IT IS THESE TWO FEATURES (THE APPROACHING WARM FRONT AND UPPER RIDGE BUILDING ACROSS THE REGION) THAT WILL DRIVE THE WEATHER PATTERN OVER THE UPPER GREAT LAKES FOR MUCH OF THE WEEK. FOR TODAY...ONGOING WARM ADVECTION THIS MORNING (H85 TEMPS ALREADY AT +10C PER 00Z APX SOUNDING) WILL CONTINUE THROUGH THE DAY AS LOW LEVEL RIDGE AXIS REMAINS PARKED OFF TO THE EAST...AND BROAD SOUTHWEST FLOW OVERSPREAD THE AREA. INITIAL SHOT OF 850-700 MB THERMAL/MOISTURE ADVECTION THIS MORNING SHOULD CONTINUE TO DRIVE AN EXPANDING LOW/MID CLOUD DECK ACROSS THE AREA...BUT THIS LIKELY TO BE SHORT LIVED (BEFORE BEING REPLACED BY CU FIELD THIS AFTERNOON)...SO PARTLY CLOUDY SHOULD DO IT. H85 TEMPS PROGGED TO JUMP TO +14C BY 00Z TONIGHT...AND THIS APPEARS LIKELY GIVEN UPSTREAM SOUNDINGS THIS PAST EVENING. SURFACE WARM FRONT LIFTING TOWARD THE AREA THIS MORNING WILL LIKELY BECOME QUITE DIFFUSE BY AFTERNOON AS IT SIMPLY MIXES NORTH TO REFOCUS ACROSS ONTARIO IN ASSOCIATION WITH DEVELOPING LEE CYCLONE OVER THE NORTHERN PLAINS. THIS WILL ESSENTIALLY LEAVE THE AREA IN WHAT WILL BECOME A VERY BROAD WARM SECTOR ACROSS MUCH OF THE CENTRAL AND EASTERN CONUS. GOOD INSOLATION AND HEATING THIS AFTERNOON SHOULD RESULT IN DECENT CONVECTIVE MIXING TO YIELD HIGHS WELL INTO THE 70S TO LOWER 80S. WITH AN INCREASE IN DEW POINTS ALSO OCCURRING...WILL HAVE TO BEGIN TO PONDER CHANCES FOR AFTERNOON CONVECTION. NAM/GFS APPEAR TO STILL BE OVERDOING SURFACE DEW POINTS...AND SUBSEQUENTLY PRODUCING SPURIOUSLY HIGH VALUES OF CAPE (1500+ J/KG). A MORE LIKELY SCENARIO FOR TODAY GIVEN EXPECTED MIXING OUT OF HIGHER THETA-E AIR YIELDS DEW POINTS INTO THE LOW AND MID 50S...WHICH STILL DOES YIELD SOME MLCAPE (300-500 J/KG OR SO). WITH REGION FALLING ON THE WESTERN FRINGE OF STILL BUILDING MID LEVEL RIDGE AND CAPPING INVERSION NOT OVERLY STRONG...APPEARS EXPECTED CAPE MAY STILL BE SUFFICIENT TO POP A FEW STORMS. THE BIGGEST PROBLEM WILL BE THE LACK OF A FORCING MECHANISM...AS LAKE BREEZES LOOK TO REMAIN MOSTLY SUPPRESSED WITH SUFFICIENT BOUNDARY LAYER FLOW (15-20 KNOTS OR SO)...THOUGH ANY WEAK TURNING OF THE WINDS OFF THE LAKES OR LOCALIZED CONVERGENCE (SUCH AS THAT WHICH OFTEN OCCURS OVER THE HIGHER TERRAIN) MAY BE SUFFICIENT TO SERVE AS A FOCUS. GIVEN OVERALL LACK OF FORCING MECHANISM AND INSTABILITY...GOING 20 POP LOOKS VERY GOOD AND WILL SIMPLY CHANGE WORDING TO `ISOLATED`. TONIGHT WILL BE THE FIRST OF A FEW WARM AND RATHER HUMID NIGHTS WITH DEW POINTS CREEPING UP AND NOT ALLOWING TEMPS TO FALL VERY MUCH. WITH LOW LEVEL RIDGE AXIS STILL ATTEMPTING TO HANG ON... SHOULD SEE WINDS SLACKEN AFTER SUNSET...AND COULD EVEN SEE A BIT OF LIGHT FOG WITH AREA FIRMLY ENTRENCHED IN LOW LEVEL THETA-E RIDGE. HAVE ALSO HELD ONTO EARLY ISOLATED TSRA MENTION WITH POTENTIAL FOR ANYTHING WHICH DEVELOPS TODAY TO HANG ON FOR A FEW HOURS AFTER SUNSET PER ELEVATED INSTABILITY IN PLACE. LOWS TONIGHT MAINLY IN THE MID TO UPPER 50S. FOR TOMORROW INTO TOMORROW NIGHT...A SIMILAR SCENARIO WITH REGARD TO CONVECTIVE POTENTIAL WILL REPEAT ITSELF...THOUGH WITH SUBTLE CHANGES TO THE OVERALL SETUP. BUILDING MID LEVEL RIDGE OVERHEAD WITH H5 HEIGHTS PROGGED BETTER THAN 582 DM WILL LIKELY RESULT IN A MORE PRONOUNCED MID LEVEL CAPPING INVERSION. HOWEVER...WITH H85 TEMPS CLIMBING EVEN A BIT HIGHER (+15C ON THE GFS/+16C ON THE ECMWF) AND SLIGHTLY BETTER MIXING EXPECTED...HIGHS WILL ALSO BE A FEW DEGREES WARMER...MAINLY IN THE MIDDLE AND EVEN UPPER 80S PER NOMOGRAMS. THIS COUPLED WITH A TOUCH HIGHER DEW POINTS (PERHAPS NEAR 60) SHOULD YIELD MLCAPES PERHAPS APPROACHING 800 J/KG...THOUGH AGAIN THE PROBLEM WILL BE A FORCING/FOCUSING MECHANISM AS FLOW APPEARS JUST A BIT TOO FAST TO SUPPORT SIGNIFICANT LAKE BREEZE COMPONENT. SO IT WILL BE A BALANCING AT AS INCREASED INSTABILITY SHOULD RESULT IN A BIT MORE WIDESPREAD DEVELOPMENT...THOUGH DEGREE OF CAPPING INVERSION SOMETHING TO BE WATCHED. WILL ALSO AGAIN HOLD OVER MENTION INTO THE LATE EVENING HOURS OF TOMORROW TO CATCH ANYTHING THAT MAY LINGER. WILL AGAIN BE ANOTHER WARM NIGHT TOMORROW NIGHT WITH LOWS MAINLY UPPER 50S. LATER PERIODS (THURSDAY INTO SATURDAY)...VERY LITTLE APPEARS LIKELY TO CHANGE THROUGH THURSDAY NIGHT AS BROAD LOW/MID LEVEL RIDGE AXIS SLIPS JUST A TAD FARTHER BUT IT STILL FIRMLY IN CONTROL OF THE WEATHER. SUBTLE HEIGHTS FALLS ASSOCIATED WITH THE EASTWARD DISPLACEMENT OF THIS FEATURE APPEAR SUFFICIENT TO PROMOTE A LESS CAPPED ENVIRONMENT. IN ADDITION...FLOW WILL BE ATTEMPTING TO BECOME SLIGHTLY DIVERGENT ALOFT AS UPPER GYRE OVER THE NORTHERN PLAINS SLOWLY PUSHES EAST. THIS COUPLED WITH CONTINUED RICH BOUNDARY LAYER MOISTURE AND SUFFICIENT HEATING IS ENOUGH TO JUSTIFY GOING CHANCE POPS INTO THURSDAY NIGHT. HIGHS A BIT MORE TRICKY ON THURSDAY PENDING POTENTIAL FOR UPSTREAM CONVECTIVE DEBRIS CLOUD TO SPILL ACROSS THE REGION...BUT WITH GOOD MIXING AND H85 TEMPS HOLDING STRONG AROUND +14C...COULD EASILY BE ANOTHER DAY IN THE 80S. THE FORECAST BEYOND THURSDAY NIGHT REMAINS QUITE MURKY WITH REGARDS TO TIMING OF SYSTEM WHICH WILL EVENTUALLY PUSH OUT OF THE PLAINS AND ACROSS THE GREAT LAKES. MODELS HAVE CONTINUED THEIR SLOWING TREND OWING TO A MORE AMPLIFIED EASTERN CONUS RIDGE AND ALSO A DEEPER CYCLONE. BEST GUESS AT THIS POINT IS FOR THE BETTER CHANCES OF MORE WIDESPREAD SHOWERS AND STORMS TO COME LATE FRIDAY INTO SATURDAY. THIS IS IN LINE WITH GFS ENSEMBLE MEAN DEPICTION OF BEST HEIGHT FALLS/SYNOPTIC SUPPORT...WHICH AGREES WITH THE MORE CONSISTENT ECMWF. TEMPS WILL TAKE A GRADUAL DOWNWARD TURN HEADING INTO THE WEEKEND AS WELL. LAWRENCE && .APX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1105 AM EDT TUE MAY 29 2007 .UPDATE... MAIN FCST ISSUE THIS AFTN IS SHRA/TSRA POTENTIAL. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A TROF OVER THE ROCKIES WITH DOWNSTREAM RIDGE EXTENDING FROM THE SE STATES N TO MI. A VERY WEAK SHORTWAVE WAS OVER NE WI/CNTRL UPPER MI. SO FAR...WAVE HAS ONLY PRODUCED SOME -SHRA/ISOLD TSRA OVER THE DOOR PENINSULA AND JUST E OF THERE. TO THE W...ANOTHER WEAK SHORTWAVE LIFTING NE THRU MN WAS PRODUCING A FEW -SHRA/ISOLD TSRA...MAINLY W OF KDLH...BUT SOME SHRA HAVE DEVELOPED EWD TOWARD THE KEWEENAW RECENTLY. VERY WEAK SHORTWAVE OVER NE WI IS HEADED MORE ERLY AROUND RIDGE AXIS WHILE SHORTWAVE IN MN IS HEADING MORE NRLY. SO...IT DOES NOT APPEAR ANY SHORTWAVES WILL DIRECTLY AFFECT THE FCST AREA THIS AFTN TO PROVIDE A FOCUS FOR WIDESPREAD SHRA/TSRA. SHORTWAVES WILL BE CLOSE ENOUGH THOUGH TO AID SHRA DEVELOPMENT OVER THE FAR W THIS AFTN AND POSSIBLY OVER THE SE FCST AREA FOR THE NEXT FEW HRS. OTHERWISE... INSTABILITY WILL BUILD AS HEATING CONTINUES...LEADING TO THE POTENTIAL OF SCT SHRA/TSRA...BUT THERE ARE NO WELL-DEFINED BOUNDARIES TO PROVIDE A STRONG FOCUS. MODIFIED KGRB SOUNDING FOR SFC T/TD OF 80/58F YIELDS SBCAPE OF ABOUT 400J/KG WHILE 80/60F YIELDS NEARLY 800J/KG. WITH LIMITED SBCAPE AND DEEP LAYER SHEAR ON THE ORDER OF 20-25KT...DO NOT ANTICIPATE ANY SVR STORMS THIS AFTN. DECENT SRLY FLOW OFF LAKE MICHIGAN SHOULD KEEP THE ERN FCST AREA STABILIZED SUFFICIENTLY TO PRECLUDE ANY SHRA/TSRA DEVELOPMENT AFTER THE POSSIBILITY OF ISOLD SHRA WITH SHORTWAVE BRUSHING THE SE OVER THE NEXT FEW HRS. 12Z RUC FCST SOUNDINGS SUPPORT A DRY FCST THERE. && .PREV DISCUSSION (ISSUED AT 344 AM EDT)... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND TONIGHT. WATER VAPOR AND RUC/NAM SHOWING A BROAD RIDGE FROM EASTERN MANITOBA TO WESTERN QUEBEC...INCLUDING OVER MUCH OF THE UPPER GREAT LAKES. TO THE WEST A CLOSED LOW IS OVER SOUTHERN SASKATCHEWAN WITH AN ACCOMPANYING TROUGH EXTENDING SOUTHWEST INTO WESTERN MONTANA. WEAK SHORTWAVES ARE TRAVELING THROUGH THE RIDGE AND ARE OVER SOUTHERN MINNESOTA... CENTRAL SOUTH DAKOTA AND IN SASKATCHEWAN. SURFACE ANALYSIS DEPICTS A 1026MB HIGH OVER THE LOWER GREAT LAKES AND A DEEP LOW OVER MIDDLE HIGH PLAINS. ANOTHER LOW IS OVER SOUTHERN MANITOBA. A WEAK FRONTAL SYSTEM STRETCHES EAST TO WEST ACROSS SOUTHERN CANADA THROUGH THIS LOW...WHILE A WARM FRONT EXTENDS EAST THROUGH NORTHEAST WISCONSIN AND THE UPPER GREAT LAKES. ALSO A COLD FRONT LINKS THE MANITOBA LOW WITH THE EASTERN COLORADO LOW. A HIGH PRESSURE CENTER IS BUILDING OVER THE THE PACIFIC NORTHWEST. NUMEROUS THUNDERSTORMS ARE FIRING NORTH OF THE MINNESOTA ARROWHEAD IN WESTERN ONTARIO...AND OVER CENTRAL DAKOTAS AND NEBRASKA IN ASSOCIATE WITH THE FRONTAL. NAM/GFS SOLUTIONS ARE IN GOOD AGREE FOR TODAY AND TONIGHT. THE UPPER GREAT LAKES RIDGE WILL BECOME MORE FOCUSED...WHILE THE LOW OVER SASKATCHEWAN DIGS INTO EASTERN MONTANA. ONE OF THE WEAK SHORTWAVES OVER SOUTH DAKOTA WILL SWEEP INTO THE WESTERN U.P. WHILE THE REST MOVES INTO WESTERN MINNESOTA. 850-500MB Q-VECTOR ANALYSIS SUGGEST AND INCREASE IN CONVERGENCE THIS AFTERNOON OVER THE WESTERN U.P. THE SURFACE HIGH OVER THE LOWER GREAT LAKES WILL SHIFT TO THE EAST COAST....WHILE THE WEST END OF THE WARM FRONT WASHES OUT. THE SURFACE LOW OVER MANITOBA WILL MOVE INTO NORTHWEST MINNESOTA DRAGGING THE COLD FRONT INTO CENTRAL MINNESOTA. ANTI-CYCLONIC FLOW AROUND THE EAST COAST HIGH WILL DRAW WARM GULF MOISTURE INTO THE THE UPPER MISSISSIPPI RIVER VALLEY AND THE UPPER GREAT LAKES. MUCAPE WILL INCREASE TO OVER 1000J/KG OVER THE WESTERN U.P. THEREFORE... ISENTROPIC ASCENT AHEAD OF THE COLD FRONT WILL TRIGGER THUNDERSTORMS AND SHOWERS OVER WISCONSIN AND WESTERN U.P. IN THE AREA OF GREATEST INSTABILITY THIS AFTERNOON...WHICH WILL BE MAINLY WEST OF US-41 FROM MARQUETTE TO ESCANABA. THE MID LEVEL LOW OVER THE MONTANA WILL STAY MAINLY OVER THE NORTHERN HIGH PLAINS TONIGHT. THE BROAD HIGH WILL CONTINUE TO BLANKET THE EASTERN THIRD OF THE CONUS. THE SURFACE LOW WILL BECOME STAGNANT OVER WESTERN MINNESOTA AND EASTERN NEBRASKA. A STATIONARY FRONT REMAINS OVER CENTRAL ONTARIO JUST NORTH OF LAKE SUPERIOR...AND OVER MINNESOTA AND EASTERN NEBRASKA. MORE WARM MOIST GULF AIR WILL CONTINUE TO BE DRAWN INTO WISCONSIN AND INTO CENTRAL ONTARIO. MODELS SHOW WEAK ISENTROPIC ASCENT OVER THE AREA. MOST OF THE Q-VECTOR CONVERGENCE WILL REMAIN NORTH OF LAKE SUPERIOR. MUCAPE VALUES SHOULD DROP OFF TO NEAR ZERO OVERNIGHT. THERE WILL BE SOME WEAK DIVERGENCE ALOFT. THUS INSTABILITY WILL BECOME MARGINAL OVERNIGHT...AND ISENTROPIC ASCENT WILL BE BARELY ENOUGH AHEAD OF THE FRONTAL SYSTEM TO TRIGGER SOME SHOWERS AND THUNDERSTORMS...SO WILL KEEP A MENTION GOING...HOWEVER...MOST OF THE THUNDERSTORM ACTIVITY WILL BE WEST AND NORTH OF THE FORECAST AREA. ON WEDNESDAY...THE GFS STARTS TO HOLD THE SURFACE LOW WEST OVER NORTHEAST SOUTH DAKOTA WHILE THE NAM/GEM/WRF FAVOR A CENTRAL MINNESOTA POSITION. THE UKMET IS A COMPROMISED SOLUTION. MODELS FAVOR THE STRONG WINDS ALOFT...SO WILL FAVOR THE MORE PROGRESS SOLUTIONS. THE MID LEVEL HIGH CONTINUES TO SLIDE DOWN THE ATLANTIC COAST WHILE THE RIDGE REMAINS STRETCHES ACROSS THE THE FORECAST AREA. MEANWHILE...THE MONTANA LOW WILL SPIN INTO SOUTHEAST MONTANA. SHORTWAVE SWEEPING THROUGH THE BASE OF THIS LOW WILL SAIL ACROSS THE FORECAST AREA. THE SURFACE LOW WILL BECOME FOCUSED OVER CENTRAL MINNESOTA WITH THE CANADIAN COLD FRONT EXTENDING ACROSS NORTHERN LAKE SUPERIOR...AND THE PLAINS COLD FRONT DRAPED SOUTHWEST INTO THE EASTERN KANSAS. DEEP MOISTURE CONTINUES TO BE DRAWN INTO THE FORECAST AREA FEEDING A CHANCE OF SHOWERS AND THUNDERSTORMS ON WEDNESDAY. THE MID LEVEL LOW OVER MONTANA WILL SLIP INTO NORTH CENTRAL SOUTH DAKOTA WHILE THE RIDGE REMAINS OVER THE FORECAST AREA WEDNESDAY NIGHT. WEAK SHORTWAVES WILL TRACK THROUGH THE RIDGE OVER THE FORECAST AREA. THE SURFACE LOW WILL LIFT INTO NORTHWEST MINNESOTA DRAGGING THE COLD FRONT INTO CENTRAL MINNESOTA. THE CANADIAN FRONTAL SYSTEM WILL REMAIN STATIONARY OVER NORTHERN LAKE SUPERIOR. ISENTROPIC ASCENT AND SHORTWAVE ENERGY WILL CONTINUE TO GENERATE A CHANCE OF SOME SHOWERS AND THUNDERSTORMS. Q-VECTOR ANALYSIS SUGGEST THAT THE MOST UNSTABLE AIR WILL BE ALONG THE CANADIAN FRONTAL SYSTEM. THE MID LEVEL LOW WILL REMAIN NEARLY STATIONARY NEAR KBIS...WITH A NUMBER OF WEAK SHORTWAVES ROTATING AROUND THIS LOW ON THURSDAY AND THURSDAY NIGHT. THE SURFACE LOW WILL ALSO BE PULLED NORTHWEST TO THE NORTH SIDE OF THE MID LEVEL LOW AND MOVE INTO NORTH CENTRAL NORTH DAKOTA. THE CANADIAN FRONTAL SYSTEM WILL REMAIN OVER CENTRAL ONTARIO. A WEAK SHORTWAVE BEING EJECTED OUT AHEAD OF THE OF MID LEVEL LOW WILL ATTEMPT TO TRAVERSE THE FORECAST AREA GENERATING A CHANCE OF SHOWERS AND THUNDERSTORMS. AS THE LOW BACKS WEST...THE ISENTROPIC ASCENT WILL ALSO WEAKEN...BUT STILL APPEARS TO BE STRONG ENOUGH TO KEEP A CHANCE OF THUNDERSTORMS GOING ESPECIALLY COUPLED WITH AFTERNOON HEATING. GUIDANCE SHOWING SURFACE DEW POINTS WILL BE HIGH ENOUGH TO PRODUCE FOG OVER THE COOL WATERS OF LAKE SUPERIOR. THE MID LEVEL RIDGE WILL START TO BREAK DOWN ON FRIDAY ALLOWING THE MID LEVEL LOW TO TREK EAST TO NEAR KJMS. THE SURFACE LOW WILL LINE UP WITH THE MID LEVEL LOW ALLOWING THE PLAINS FRONTAL SYSTEM TO MOVE INTO WESTERN IOWA. THE CANADIAN FRONT SYSTEM WILL LIKEWISE REMAIN WEAK AND OVER THE NORTHERN LAKE SUPERIOR. SHOWERS AND THUNDERSTORMS WILL CONTINUE TO BE A REAL POSSIBILITY. CURRENT GRIDS LOOK OK FOR NOW. && .MARINE (FOR 4 PM ISSUANCE OF LAKE SUPERIOR FCST)... EXPECT HIGH PRES OVER LAKE ONTARIO TO DRIFT OFF THE MID ATLANTIC COAST ON THU WHILE A LOW PRES JUST S OF LAKE WINNIPEG THIS MORNING MEANDERS SLOWLY TO THE E. THIS LOW WILL GRADUALLY PUSH INTO THE UPPER GREAT LAKES THROUGH THE WEEKEND AND WEAKEN. WINDS OVER THE LK TDAY WL RESPOND TO LK BREEZE CIRCULATION TDAY AFT MOSTLY DECOUPLED NOCTURNAL LLJ WEAKENS. LLJ TNGT WL NOT BE AS STRG WITH LACK OF PRES FALL CENTER ACRS ONTARIO. OTRW...FOLLOWED CNDN MODEL PER NCEP PREFERENCE FOR WINDS THRU THE REST OF THE WEEK. THIS MODEL IS QUITE A BIT SLOWER TO PUSH SFC LO E THAN INDICATED BY PREVIOUS GUIDANCE. CNDN SOLN PROMISES A WEAK PRES GRADIENT...SO WINDS WL BE ON THE LGT SIDE AND RESPOND TO LK BREEZE CIRCULATIONS IN THE DAY. FOG SHOULD BECOME AN ISSUE TUE NIGHT THRU THU ONCE SOME RAINFALL OCCURS OVER THE LAKE AND MOISTENS THE CHILLY MARINE LYR UNDER SHARP INVRN. && .AVIATION (FOR 12Z TAFS)... EXPECT DAYTIME MIXING TO END LLWS THIS MRNG. COMBINATION OF THIS MIXING AND MSTR ARRIVING FM THE S SHOULD ALLOW DVLPMNT OF VFR SC CIGS TDAY. INCLUDED PROB30 GROUPS FOR SHRA LATER TDAY AS INCREASING LOW-LEVEL MOISTURE AND AFTERNOON HEATING WILL LEAD TO INCRSG INSTABILITY OVER THE AREA. BUT LACK OF BNDRY AND GENERAL LARGER SCALE ACYC FLOW WL LIMIT COVG/INTENSITY OF ANY SHRA. OTRW...RELATIVE DRYNESS OF THE LLVLS WL MAINTAIN VFR CONDITIONS THRU THE FCST PD EXCEPT PSBLY UNDER ANY SHRA. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...ROLFSON PREV DISCUSSION...DLG MARINE/AVIATION...KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1048 AM EDT TUE MAY 29 2007 .UPDATE...LOW AND MID LEVEL WAA AND MOISTURE FLUX WELL UNDERWAY ACROSS THE NORTHERN LAKES ON UPSTREAM SIDE OF HIGH PRESSURE CENTERED OVER WESTERN NEW YORK...AS EVIDENT BY BROKEN MID LEVEL CU/ALTOCU DECK WORKING NORTHEAST ACROSS THE AREA AND LOCAL PWAT JUMPING FROM 0.36 INCHES ON LAST NIGHTS 00Z SOUNDING TO 1.02 INCHES WITH THIS MORNINGS RELEASE. HOWEVER...AS IS OFTEN THE CASE...GFS/NAM-WRF MODEL GUIDANCE OVERDOING LOW LEVEL MOISTENING...WITH OBSERVED UPPER 40 TO LOW 50 DEWPOINTS SEVERAL DEGREES LOWER THAN MODEL PROGS. FORECAST CONCERNS FOR THE REMAINDER OF THE DAY CENTER ON AFTERNOON CONVECTIVE POTENTIAL AS DAYTIME HEATING WORKS ON INCREASING MOISTURE. NOT A WHOLE LOT TO HANG YOUR HAT ON AS FAR AS A FOCUS FOR CONVECTION THIS AFTERNOON WITH LACK OF SYNOPTIC SCALE SURFACE BOUNDARY AND SOUTHWEST FLOW 950MB WINDS RAMPING UP TO 15 TO 25 KNOTS SEVERELY LIMITING LAKE BREEZE POTENTIAL. IN ADDITION...WILL IGNORE OVER ZEALOUS NAM-WRF/GFS SURFACE INSTABILITY PROGS SHOWING 1500+ J/KG CAPE (PRIMARILY A FUNCTION OF OVER MOISTENING...WITH THESE MODELS SUGGESTING SURFACE DEWPOINTS REACHING THE LOW 60S BY LATER THIS AFTERNOON). TAKING MORE CONSERVATIVE LOW TO MID 50 DEWPOINTS FOR THE AFTERNOON (LATEST RUC GUIDANCE ALSO SHOWING DEWPOINTS IN THIS RANGE) INDICATES MEAN LAYER CAPE OF ONLY 100 J/KG OR SO. THIS SHOULD BE JUST ENOUGH INSTABILITY...COMBINED WITH ANY SUBTLE LAKE INDUCED WIND CHANGE OR ENHANCED SURFACE CONVERGENCE IN HIGHER TERRAIN LOCALS...TO KICK OFF AN ISOLATED SHOWER OR THUNDERSTORM. OTHERWISE...STILL EXPECTING TEMPERATURES TO TOP OFF IN THE MID 70S TO LOW 80S AS BOUNDARY LAYER MIXING HELPS SCOUR SOME OF THIS MORNINGS CLOUD DECK. OTHERWISE...REST OF FORECAST IN GREAT SHAPE WITH NO CHANGES WARRANTED. UPDATED GRIDS/ZONES/NEARSHORES OUT SHORTLY. MSB && .AVIATION...ISSUED AT 725 AM OW/MID CLOUD DECK WILL CONTINUE TO OVERSPREAD ALL 3 TAF SITES THIS MORNING...THOUGH CEILINGS ARE EXPECTED TO REMAIN VFR WITH BASES AROUND 4-5KFT AT THE LOWEST. SHOULD SEE THESE ON THE WANE BY LATE MORNING...THOUGH WITH MOISTURE FLOWING INTO THE REGION AND WARM AFTERNOON TEMPERATURES...CU/STRATOCU DECK WILL FILL IN BY EARLY AFTERNOON. AN OUTSIDE CHANCE AT AN ISOLATED SHOWER OR THUNDERSTORM ALSO EXISTS OVER THE ENTIRE AREA BY LATE AFTERNOON INTO EARLY EVENING...THOUGH POSSIBILITIES FAR TOO SMALL TO MAKE ANY MENTION IN THE TAFS. WINDS WILL PICK UP JUST A BIT BY AFTERNOON...GENERALLY AROUND 10-15 KNOTS AT THEIR HIGHEST....BEFORE SLACKENING ONCE AGAIN AFTER SUNSET. WITH HIGH DEW POINTS IN PLACE AND RELATIVELY LIGHT WINDS...WILL LIKELY SEE SOME REDUCTION IN VISIBILITIES OVERNIGHT WITH MIST/LIGHT FOG...SIMILAR TO WHAT IS OCCURRING UPSTREAM THIS MORNING. THUS HAVE INCLUDED A MENTION OF THIS POSSIBILITY...ALTHOUGH WITH SOME UNCERTAINTY ABOUT HOW HIGH DEW POINTS WILL END UP...HAVE KEPT VISIBILITIES IN VFR RANGE...THOUGH COULD EASILY BE MVFR. LAWRENCE && .PREV DISCUSSION... /ISSUED 337 AM EDT TUE MAY 29 2007/ DISCUSSION...A SEEMINGLY BROKEN RECORD FORECAST APPEARS ON TAP FOR MUCH IF NOT ALL OF THE WORK WEEK...AND POTENTIALLY HEADING INTO THE WEEKEND...WITH WARM AND HUMID CONDITIONS IN PLACE ALONG WITH OCCASIONAL CHANCES FOR CONVECTION. THE MAIN FORECAST CHALLENGES THROUGH THE NEXT 5 DAYS ARE JUST HOW WARM THINGS WILL GET EACH AFTERNOON...ALONG WITH TIMING/COVERAGE OF ALMOST DAILY CHANCES FOR CONVECTION. EARLY MORNING SUBJECTIVE ANALYSIS PLACES AN ELONGATED BUT FAIRLY WEAK (1024MB) SURFACE RIDGE OVER THE EASTERN GREAT LAKES AND INTO THE NORTHEAST...WITH A STATIONARY FRONT DRAPED OVER THE NORTHERN OHIO VALLEY BEFORE BECOMING A WARM FRONT OVER THE MID MISSISSIPPI VALLEY IN DEVELOPING RETURN FLOW/WARM ADVECTION REGIME. ALOFT...RATHER IMPRESSIVE SHORTWAVE PER EVENING WATER VAPOR PICS NOTED DIVING INTO EASTERN IDAHO...WITH HEIGHT FALLS EMERGING ONTO THE WESTERN HIGH PLAINS DRIVING SURFACE CYCLOGENESIS OVER THIS REGION...BUT AIDING IN DOWNSTREAM HEIGHT RISES OVER MUCH OF THE EASTERN CONUS AS UPPER RIDGE BEGINS TO BUILD. IT IS THESE TWO FEATURES (THE APPROACHING WARM FRONT AND UPPER RIDGE BUILDING ACROSS THE REGION) THAT WILL DRIVE THE WEATHER PATTERN OVER THE UPPER GREAT LAKES FOR MUCH OF THE WEEK. FOR TODAY...ONGOING WARM ADVECTION THIS MORNING (H85 TEMPS ALREADY AT +10C PER 00Z APX SOUNDING) WILL CONTINUE THROUGH THE DAY AS LOW LEVEL RIDGE AXIS REMAINS PARKED OFF TO THE EAST...AND BROAD SOUTHWEST FLOW OVERSPREAD THE AREA. INITIAL SHOT OF 850-700 MB THERMAL/MOISTURE ADVECTION THIS MORNING SHOULD CONTINUE TO DRIVE AN EXPANDING LOW/MID CLOUD DECK ACROSS THE AREA...BUT THIS LIKELY TO BE SHORT LIVED (BEFORE BEING REPLACED BY CU FIELD THIS AFTERNOON)...SO PARTLY CLOUDY SHOULD DO IT. H85 TEMPS PROGGED TO JUMP TO +14C BY 00Z TONIGHT...AND THIS APPEARS LIKELY GIVEN UPSTREAM SOUNDINGS THIS PAST EVENING. SURFACE WARM FRONT LIFTING TOWARD THE AREA THIS MORNING WILL LIKELY BECOME QUITE DIFFUSE BY AFTERNOON AS IT SIMPLY MIXES NORTH TO REFOCUS ACROSS ONTARIO IN ASSOCIATION WITH DEVELOPING LEE CYCLONE OVER THE NORTHERN PLAINS. THIS WILL ESSENTIALLY LEAVE THE AREA IN WHAT WILL BECOME A VERY BROAD WARM SECTOR ACROSS MUCH OF THE CENTRAL AND EASTERN CONUS. GOOD INSOLATION AND HEATING THIS AFTERNOON SHOULD RESULT IN DECENT CONVECTIVE MIXING TO YIELD HIGHS WELL INTO THE 70S TO LOWER 80S. WITH AN INCREASE IN DEW POINTS ALSO OCCURRING...WILL HAVE TO BEGIN TO PONDER CHANCES FOR AFTERNOON CONVECTION. NAM/GFS APPEAR TO STILL BE OVERDOING SURFACE DEW POINTS...AND SUBSEQUENTLY PRODUCING SPURIOUSLY HIGH VALUES OF CAPE (1500+ J/KG). A MORE LIKELY SCENARIO FOR TODAY GIVEN EXPECTED MIXING OUT OF HIGHER THETA-E AIR YIELDS DEW POINTS INTO THE LOW AND MID 50S...WHICH STILL DOES YIELD SOME MLCAPE (300-500 J/KG OR SO). WITH REGION FALLING ON THE WESTERN FRINGE OF STILL BUILDING MID LEVEL RIDGE AND CAPPING INVERSION NOT OVERLY STRONG...APPEARS EXPECTED CAPE MAY STILL BE SUFFICIENT TO POP A FEW STORMS. THE BIGGEST PROBLEM WILL BE THE LACK OF A FORCING MECHANISM...AS LAKE BREEZES LOOK TO REMAIN MOSTLY SUPPRESSED WITH SUFFICIENT BOUNDARY LAYER FLOW (15-20 KNOTS OR SO)...THOUGH ANY WEAK TURNING OF THE WINDS OFF THE LAKES OR LOCALIZED CONVERGENCE (SUCH AS THAT WHICH OFTEN OCCURS OVER THE HIGHER TERRAIN) MAY BE SUFFICIENT TO SERVE AS A FOCUS. GIVEN OVERALL LACK OF FORCING MECHANISM AND INSTABILITY...GOING 20 POP LOOKS VERY GOOD AND WILL SIMPLY CHANGE WORDING TO `ISOLATED`. TONIGHT WILL BE THE FIRST OF A FEW WARM AND RATHER HUMID NIGHTS WITH DEW POINTS CREEPING UP AND NOT ALLOWING TEMPS TO FALL VERY MUCH. WITH LOW LEVEL RIDGE AXIS STILL ATTEMPTING TO HANG ON... SHOULD SEE WINDS SLACKEN AFTER SUNSET...AND COULD EVEN SEE A BIT OF LIGHT FOG WITH AREA FIRMLY ENTRENCHED IN LOW LEVEL THETA-E RIDGE. HAVE ALSO HELD ONTO EARLY ISOLATED TSRA MENTION WITH POTENTIAL FOR ANYTHING WHICH DEVELOPS TODAY TO HANG ON FOR A FEW HOURS AFTER SUNSET PER ELEVATED INSTABILITY IN PLACE. LOWS TONIGHT MAINLY IN THE MID TO UPPER 50S. FOR TOMORROW INTO TOMORROW NIGHT...A SIMILAR SCENARIO WITH REGARD TO CONVECTIVE POTENTIAL WILL REPEAT ITSELF...THOUGH WITH SUBTLE CHANGES TO THE OVERALL SETUP. BUILDING MID LEVEL RIDGE OVERHEAD WITH H5 HEIGHTS PROGGED BETTER THAN 582 DM WILL LIKELY RESULT IN A MORE PRONOUNCED MID LEVEL CAPPING INVERSION. HOWEVER...WITH H85 TEMPS CLIMBING EVEN A BIT HIGHER (+15C ON THE GFS/+16C ON THE ECMWF) AND SLIGHTLY BETTER MIXING EXPECTED...HIGHS WILL ALSO BE A FEW DEGREES WARMER...MAINLY IN THE MIDDLE AND EVEN UPPER 80S PER NOMOGRAMS. THIS COUPLED WITH A TOUCH HIGHER DEW POINTS (PERHAPS NEAR 60) SHOULD YIELD MLCAPES PERHAPS APPROACHING 800 J/KG...THOUGH AGAIN THE PROBLEM WILL BE A FORCING/FOCUSING MECHANISM AS FLOW APPEARS JUST A BIT TOO FAST TO SUPPORT SIGNIFICANT LAKE BREEZE COMPONENT. SO IT WILL BE A BALANCING AT AS INCREASED INSTABILITY SHOULD RESULT IN A BIT MORE WIDESPREAD DEVELOPMENT...THOUGH DEGREE OF CAPPING INVERSION SOMETHING TO BE WATCHED. WILL ALSO AGAIN HOLD OVER MENTION INTO THE LATE EVENING HOURS OF TOMORROW TO CATCH ANYTHING THAT MAY LINGER. WILL AGAIN BE ANOTHER WARM NIGHT TOMORROW NIGHT WITH LOWS MAINLY UPPER 50S. LATER PERIODS (THURSDAY INTO SATURDAY)...VERY LITTLE APPEARS LIKELY TO CHANGE THROUGH THURSDAY NIGHT AS BROAD LOW/MID LEVEL RIDGE AXIS SLIPS JUST A TAD FARTHER BUT IT STILL FIRMLY IN CONTROL OF THE WEATHER. SUBTLE HEIGHTS FALLS ASSOCIATED WITH THE EASTWARD DISPLACEMENT OF THIS FEATURE APPEAR SUFFICIENT TO PROMOTE A LESS CAPPED ENVIRONMENT. IN ADDITION...FLOW WILL BE ATTEMPTING TO BECOME SLIGHTLY DIVERGENT ALOFT AS UPPER GYRE OVER THE NORTHERN PLAINS SLOWLY PUSHES EAST. THIS COUPLED WITH CONTINUED RICH BOUNDARY LAYER MOISTURE AND SUFFICIENT HEATING IS ENOUGH TO JUSTIFY GOING CHANCE POPS INTO THURSDAY NIGHT. HIGHS A BIT MORE TRICKY ON THURSDAY PENDING POTENTIAL FOR UPSTREAM CONVECTIVE DEBRIS CLOUD TO SPILL ACROSS THE REGION...BUT WITH GOOD MIXING AND H85 TEMPS HOLDING STRONG AROUND +14C...COULD EASILY BE ANOTHER DAY IN THE 80S. THE FORECAST BEYOND THURSDAY NIGHT REMAINS QUITE MURKY WITH REGARDS TO TIMING OF SYSTEM WHICH WILL EVENTUALLY PUSH OUT OF THE PLAINS AND ACROSS THE GREAT LAKES. MODELS HAVE CONTINUED THEIR SLOWING TREND OWING TO A MORE AMPLIFIED EASTERN CONUS RIDGE AND ALSO A DEEPER CYCLONE. BEST GUESS AT THIS POINT IS FOR THE BETTER CHANCES OF MORE WIDESPREAD SHOWERS AND STORMS TO COME LATE FRIDAY INTO SATURDAY. THIS IS IN LINE WITH GFS ENSEMBLE MEAN DEPICTION OF BEST HEIGHT FALLS/SYNOPTIC SUPPORT...WHICH AGREES WITH THE MORE CONSISTENT ECMWF. TEMPS WILL TAKE A GRADUAL DOWNWARD TURN HEADING INTO THE WEEKEND AS WELL. LAWRENCE && .APX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ mi AREA FORECAST DISCUSSION...UPDATED FOR 12Z AVIATION FCST NATIONAL WEATHER SERVICE MARQUETTE MI 735 AM EDT TUE MAY 29 2007 .DISCUSSION (ISSUED AT 344 AM EDT)... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND TONIGHT. WATER VAPOR AND RUC/NAM SHOWING A BROAD RIDGE FROM EASTERN MANITOBA TO WESTERN QUEBEC...INCLUDING OVER MUCH OF THE UPPER GREAT LAKES. TO THE WEST A CLOSED LOW IS OVER SOUTHERN SASKATCHEWAN WITH AN ACCOMPANYING TROUGH EXTENDING SOUTHWEST INTO WESTERN MONTANA. WEAK SHORTWAVES ARE TRAVELING THROUGH THE RIDGE AND ARE OVER SOUTHERN MINNESOTA... CENTRAL SOUTH DAKOTA AND IN SASKATCHEWAN. SURFACE ANALYSIS DEPICTS A 1026MB HIGH OVER THE LOWER GREAT LAKES AND A DEEP LOW OVER MIDDLE HIGH PLAINS. ANOTHER LOW IS OVER SOUTHERN MANITOBA. A WEAK FRONTAL SYSTEM STRETCHES EAST TO WEST ACROSS SOUTHERN CANADA THROUGH THIS LOW...WHILE A WARM FRONT EXTENDS EAST THROUGH NORTHEAST WISCONSIN AND THE UPPER GREAT LAKES. ALSO A COLD FRONT LINKS THE MANITOBA LOW WITH THE EASTERN COLORADO LOW. A HIGH PRESSURE CENTER IS BUILDING OVER THE THE PACIFIC NORTHWEST. NUMEROUS THUNDERSTORMS ARE FIRING NORTH OF THE MINNESOTA ARROWHEAD IN WESTERN ONTARIO...AND OVER CENTRAL DAKOTAS AND NEBRASKA IN ASSOCIATE WITH THE FRONTAL. NAM/GFS SOLUTIONS ARE IN GOOD AGREE FOR TODAY AND TONIGHT. THE UPPER GREAT LAKES RIDGE WILL BECOME MORE FOCUSED...WHILE THE LOW OVER SASKATCHEWAN DIGS INTO EASTERN MONTANA. ONE OF THE WEAK SHORTWAVES OVER SOUTH DAKOTA WILL SWEEP INTO THE WESTERN U.P. WHILE THE REST MOVES INTO WESTERN MINNESOTA. 850-500MB Q-VECTOR ANALYSIS SUGGEST AND INCREASE IN CONVERGENCE THIS AFTERNOON OVER THE WESTERN U.P. THE SURFACE HIGH OVER THE LOWER GREAT LAKES WILL SHIFT TO THE EAST COAST....WHILE THE WEST END OF THE WARM FRONT WASHES OUT. THE SURFACE LOW OVER MANITOBA WILL MOVE INTO NORTHWEST MINNESOTA DRAGGING THE COLD FRONT INTO CENTRAL MINNESOTA. ANTI-CYCLONIC FLOW AROUND THE EAST COAST HIGH WILL DRAW WARM GULF MOISTURE INTO THE THE UPPER MISSISSIPPI RIVER VALLEY AND THE UPPER GREAT LAKES. MUCAPE WILL INCREASE TO OVER 1000J/KG OVER THE WESTERN U.P. THEREFORE... ISENTROPIC ASCENT AHEAD OF THE COLD FRONT WILL TRIGGER THUNDERSTORMS AND SHOWERS OVER WISCONSIN AND WESTERN U.P. IN THE AREA OF GREATEST INSTABILITY THIS AFTERNOON...WHICH WILL BE MAINLY WEST OF US-41 FROM MARQUETTE TO ESCANABA. THE MID LEVEL LOW OVER THE MONTANA WILL STAY MAINLY OVER THE NORTHERN HIGH PLAINS TONIGHT. THE BROAD HIGH WILL CONTINUE TO BLANKET THE EASTERN THIRD OF THE CONUS. THE SURFACE LOW WILL BECOME STAGNANT OVER WESTERN MINNESOTA AND EASTERN NEBRASKA. A STATIONARY FRONT REMAINS OVER CENTRAL ONTARIO JUST NORTH OF LAKE SUPERIOR...AND OVER MINNESOTA AND EASTERN NEBRASKA. MORE WARM MOIST GULF AIR WILL CONTINUE TO BE DRAWN INTO WISCONSIN AND INTO CENTRAL ONTARIO. MODELS SHOW WEAK ISENTROPIC ASCENT OVER THE AREA. MOST OF THE Q-VECTOR CONVERGENCE WILL REMAIN NORTH OF LAKE SUPERIOR. MUCAPE VALUES SHOULD DROP OFF TO NEAR ZERO OVERNIGHT. THERE WILL BE SOME WEAK DIVERGENCE ALOFT. THUS INSTABILITY WILL BECOME MARGINAL OVERNIGHT...AND ISENTROPIC ASCENT WILL BE BARELY ENOUGH AHEAD OF THE FRONTAL SYSTEM TO TRIGGER SOME SHOWERS AND THUNDERSTORMS...SO WILL KEEP A MENTION GOING...HOWEVER...MOST OF THE THUNDERSTORM ACTIVITY WILL BE WEST AND NORTH OF THE FORECAST AREA. ON WEDNESDAY...THE GFS STARTS TO HOLD THE SURFACE LOW WEST OVER NORTHEAST SOUTH DAKOTA WHILE THE NAM/GEM/WRF FAVOR A CENTRAL MINNESOTA POSITION. THE UKMET IS A COMPROMISED SOLUTION. MODELS FAVOR THE STRONG WINDS ALOFT...SO WILL FAVOR THE MORE PROGRESS SOLUTIONS. THE MID LEVEL HIGH CONTINUES TO SLIDE DOWN THE ATLANTIC COAST WHILE THE RIDGE REMAINS STRETCHES ACROSS THE THE FORECAST AREA. MEANWHILE...THE MONTANA LOW WILL SPIN INTO SOUTHEAST MONTANA. SHORTWAVE SWEEPING THROUGH THE BASE OF THIS LOW WILL SAIL ACROSS THE FORECAST AREA. THE SURFACE LOW WILL BECOME FOCUSED OVER CENTRAL MINNESOTA WITH THE CANADIAN COLD FRONT EXTENDING ACROSS NORTHERN LAKE SUPERIOR...AND THE PLAINS COLD FRONT DRAPED SOUTHWEST INTO THE EASTERN KANSAS. DEEP MOISTURE CONTINUES TO BE DRAWN INTO THE FORECAST AREA FEEDING A CHANCE OF SHOWERS AND THUNDERSTORMS ON WEDNESDAY. THE MID LEVEL LOW OVER MONTANA WILL SLIP INTO NORTH CENTRAL SOUTH DAKOTA WHILE THE RIDGE REMAINS OVER THE FORECAST AREA WEDNESDAY NIGHT. WEAK SHORTWAVES WILL TRACK THROUGH THE RIDGE OVER THE FORECAST AREA. THE SURFACE LOW WILL LIFT INTO NORTHWEST MINNESOTA DRAGGING THE COLD FRONT INTO CENTRAL MINNESOTA. THE CANADIAN FRONTAL SYSTEM WILL REMAIN STATIONARY OVER NORTHERN LAKE SUPERIOR. ISENTROPIC ASCENT AND SHORTWAVE ENERGY WILL CONTINUE TO GENERATE A CHANCE OF SOME SHOWERS AND THUNDERSTORMS. Q-VECTOR ANALYSIS SUGGEST THAT THE MOST UNSTABLE AIR WILL BE ALONG THE CANADIAN FRONTAL SYSTEM. THE MID LEVEL LOW WILL REMAIN NEARLY STATIONARY NEAR KBIS...WITH A NUMBER OF WEAK SHORTWAVES ROTATING AROUND THIS LOW ON THURSDAY AND THURSDAY NIGHT. THE SURFACE LOW WILL ALSO BE PULLED NORTHWEST TO THE NORTH SIDE OF THE MID LEVEL LOW AND MOVE INTO NORTH CENTRAL NORTH DAKOTA. THE CANADIAN FRONTAL SYSTEM WILL REMAIN OVER CENTRAL ONTARIO. A WEAK SHORTWAVE BEING EJECTED OUT AHEAD OF THE OF MID LEVEL LOW WILL ATTEMPT TO TRAVERSE THE FORECAST AREA GENERATING A CHANCE OF SHOWERS AND THUNDERSTORMS. AS THE LOW BACKS WEST...THE ISENTROPIC ASCENT WILL ALSO WEAKEN...BUT STILL APPEARS TO BE STRONG ENOUGH TO KEEP A CHANCE OF THUNDERSTORMS GOING ESPECIALLY COUPLED WITH AFTERNOON HEATING. GUIDANCE SHOWING SURFACE DEW POINTS WILL BE HIGH ENOUGH TO PRODUCE FOG OVER THE COOL WATERS OF LAKE SUPERIOR. THE MID LEVEL RIDGE WILL START TO BREAK DOWN ON FRIDAY ALLOWING THE MID LEVEL LOW TO TREK EAST TO NEAR KJMS. THE SURFACE LOW WILL LINE UP WITH THE MID LEVEL LOW ALLOWING THE PLAINS FRONTAL SYSTEM TO MOVE INTO WESTERN IOWA. THE CANADIAN FRONT SYSTEM WILL LIKEWISE REMAIN WEAK AND OVER THE NORTHERN LAKE SUPERIOR. SHOWERS AND THUNDERSTORMS WILL CONTINUE TO BE A REAL POSSIBILITY. CURRENT GRIDS LOOK OK FOR NOW. && .MARINE (FOR 4 PM ISSUANCE OF LAKE SUPERIOR FCST)... EXPECT HIGH PRES OVER LAKE ONTARIO TO DRIFT OFF THE MID ATLANTIC COAST ON THU WHILE A LOW PRES JUST S OF LAKE WINNIPEG THIS MORNING MEANDERS SLOWLY TO THE E. THIS LOW WILL GRADUALLY PUSH INTO THE UPPER GREAT LAKES THROUGH THE WEEKEND AND WEAKEN. WINDS OVER THE LK TDAY WL RESPOND TO LK BREEZE CIRCULATION TDAY AFT MOSTLY DECOUPLED NOCTURNAL LLJ WEAKENS. LLJ TNGT WL NOT BE AS STRG WITH LACK OF PRES FALL CENTER ACRS ONTARIO. OTRW...FOLLOWED CNDN MODEL PER NCEP PREFERENCE FOR WINDS THRU THE REST OF THE WEEK. THIS MODEL IS QUITE A BIT SLOWER TO PUSH SFC LO E THAN INDICATED BY PREVIOUS GUIDANCE. CNDN SOLN PROMISES A WEAK PRES GRADIENT...SO WINDS WL BE ON THE LGT SIDE AND RESPOND TO LK BREEZE CIRCULATIONS IN THE DAY. FOG SHOULD BECOME AN ISSUE TUE NIGHT THRU THU ONCE SOME RAINFALL OCCURS OVER THE LAKE AND MOISTENS THE CHILLY MARINE LYR UNDER SHARP INVRN. && .AVIATION (FOR 12Z TAFS)... EXPECT DAYTIME MIXING TO END LLWS THIS MRNG. COMBINATION OF THIS MIXING AND MSTR ARRIVING FM THE S SHOULD ALLOW DVLPMNT OF VFR SC CIGS TDAY. INCLUDED PROB30 GROUPS FOR SHRA LATER TDAY AS INCREASING LOW-LEVEL MOISTURE AND AFTERNOON HEATING WILL LEAD TO INCRSG INSTABILITY OVER THE AREA. BUT LACK OF BNDRY AND GENERAL LARGER SCALE ACYC FLOW WL LIMIT COVG/INTENSITY OF ANY SHRA. OTRW...RELATIVE DRYNESS OF THE LLVLS WL MAINTAIN VFR CONDITIONS THRU THE FCST PD EXCEPT PSBLY UNDER ANY SHRA. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...DLG MARINE/AVIATION...KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 344 AM EDT TUE MAY 29 2007 .DISCUSSION...THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND TONIGHT. WATER VAPOR AND RUC/NAM SHOWING A BROAD RIDGE FROM EASTERN MANITOBA TO WESTERN QUEBEC...INCLUDING OVER MUCH OF THE UPPER GREAT LAKES. TO THE WEST A CLOSED LOW IS OVER SOUTHERN SASKATCHEWAN WITH AN ACCOMPANYING TROUGH EXTENDING SOUTHWEST INTO WESTERN MONTANA. WEAK SHORTWAVES ARE TRAVELING THROUGH THE RIDGE AND ARE OVER SOUTHERN MINNESOTA... CENTRAL SOUTH DAKOTA AND IN SASKATCHEWAN. SURFACE ANALYSIS DEPICTS A 1026MB HIGH OVER THE LOWER GREAT LAKES AND A DEEP LOW OVER MIDDLE HIGH PLAINS. ANOTHER LOW IS OVER SOUTHERN MANITOBA. A WEAK FRONTAL SYSTEM STRETCHES EAST TO WEST ACROSS SOUTHERN CANADA THROUGH THIS LOW...WHILE A WARM FRONT EXTENDS EAST THROUGH NORTHEAST WISCONSIN AND THE UPPER GREAT LAKES. ALSO A COLD FRONT LINKS THE MANITOBA LOW WITH THE EASTERN COLORADO LOW. A HIGH PRESSURE CENTER IS BUILDING OVER THE THE PACIFIC NORTHWEST. NUMEROUS THUNDERSTORMS ARE FIRING NORTH OF THE MINNESOTA ARROWHEAD IN WESTERN ONTARIO...AND OVER CENTRAL DAKOTAS AND NEBRASKA IN ASSOCIATE WITH THE FRONTAL. NAM/GFS SOLUTIONS ARE IN GOOD AGREE FOR TODAY AND TONIGHT. THE UPPER GREAT LAKES RIDGE WILL BECOME MORE FOCUSED...WHILE THE LOW OVER SASKATCHEWAN DIGS INTO EASTERN MONTANA. ONE OF THE WEAK SHORTWAVES OVER SOUTH DAKOTA WILL SWEEP INTO THE WESTERN U.P. WHILE THE REST MOVES INTO WESTERN MINNESOTA. 850-500MB Q-VECTOR ANALYSIS SUGGEST AND INCREASE IN CONVERGENCE THIS AFTERNOON OVER THE WESTERN U.P. THE SURFACE HIGH OVER THE LOWER GREAT LAKES WILL SHIFT TO THE EAST COAST....WHILE THE WEST END OF THE WARM FRONT WASHES OUT. THE SURFACE LOW OVER MANITOBA WILL MOVE INTO NORTHWEST MINNESOTA DRAGGING THE COLD FRONT INTO CENTRAL MINNESOTA. ANTI-CYCLONIC FLOW AROUND THE EAST COAST HIGH WILL DRAW WARM GULF MOISTURE INTO THE THE UPPER MISSISSIPPI RIVER VALLEY AND THE UPPER GREAT LAKES. MUCAPE WILL INCREASE TO OVER 1000J/KG OVER THE WESTERN U.P. THEREFORE... ISENTROPIC ASCENT AHEAD OF THE COLD FRONT WILL TRIGGER THUNDERSTORMS AND SHOWERS OVER WISCONSIN AND WESTERN U.P. IN THE AREA OF GREATEST INSTABILITY THIS AFTERNOON...WHICH WILL BE MAINLY WEST OF US-41 FROM MARQUETTE TO ESCANABA. THE MID LEVEL LOW OVER THE MONTANA WILL STAY MAINLY OVER THE NORTHERN HIGH PLAINS TONIGHT. THE BROAD HIGH WILL CONTINUE TO BLANKET THE EASTERN THIRD OF THE CONUS. THE SURFACE LOW WILL BECOME STAGNANT OVER WESTERN MINNESOTA AND EASTERN NEBRASKA. A STATIONARY FRONT REMAINS OVER CENTRAL ONTARIO JUST NORTH OF LAKE SUPERIOR...AND OVER MINNESOTA AND EASTERN NEBRASKA. MORE WARM MOIST GULF AIR WILL CONTINUE TO BE DRAWN INTO WISCONSIN AND INTO CENTRAL ONTARIO. MODELS SHOW WEAK ISENTROPIC ASCENT OVER THE AREA. MOST OF THE Q-VECTOR CONVERGENCE WILL REMAIN NORTH OF LAKE SUPERIOR. MUCAPE VALUES SHOULD DROP OFF TO NEAR ZERO OVERNIGHT. THERE WILL BE SOME WEAK DIVERGENCE ALOFT. THUS INSTABILITY WILL BECOME MARGINAL OVERNIGHT...AND ISENTROPIC ASCENT WILL BE BARELY ENOUGH AHEAD OF THE FRONTAL SYSTEM TO TRIGGER SOME SHOWERS AND THUNDERSTORMS...SO WILL KEEP A MENTION GOING...HOWEVER...MOST OF THE THUNDERSTORM ACTIVITY WILL BE WEST AND NORTH OF THE FORECAST AREA. ON WEDNESDAY...THE GFS STARTS TO HOLD THE SURFACE LOW WEST OVER NORTHEAST SOUTH DAKOTA WHILE THE NAM/GEM/WRF FAVOR A CENTRAL MINNESOTA POSITION. THE UKMET IS A COMPROMISED SOLUTION. MODELS FAVOR THE STRONG WINDS ALOFT...SO WILL FAVOR THE MORE PROGRESS SOLUTIONS. THE MID LEVEL HIGH CONTINUES TO SLIDE DOWN THE ATLANTIC COAST WHILE THE RIDGE REMAINS STRETCHES ACROSS THE THE FORECAST AREA. MEANWHILE...THE MONTANA LOW WILL SPIN INTO SOUTHEAST MONTANA. SHORTWAVE SWEEPING THROUGH THE BASE OF THIS LOW WILL SAIL ACROSS THE FORECAST AREA. THE SURFACE LOW WILL BECOME FOCUSED OVER CENTRAL MINNESOTA WITH THE CANADIAN COLD FRONT EXTENDING ACROSS NORTHERN LAKE SUPERIOR...AND THE PLAINS COLD FRONT DRAPED SOUTHWEST INTO THE EASTERN KANSAS. DEEP MOISTURE CONTINUES TO BE DRAWN INTO THE FORECAST AREA FEEDING A CHANCE OF SHOWERS AND THUNDERSTORMS ON WEDNESDAY. THE MID LEVEL LOW OVER MONTANA WILL SLIP INTO NORTH CENTRAL SOUTH DAKOTA WHILE THE RIDGE REMAINS OVER THE FORECAST AREA WEDNESDAY NIGHT. WEAK SHORTWAVES WILL TRACK THROUGH THE RIDGE OVER THE FORECAST AREA. THE SURFACE LOW WILL LIFT INTO NORTHWEST MINNESOTA DRAGGING THE COLD FRONT INTO CENTRAL MINNESOTA. THE CANADIAN FRONTAL SYSTEM WILL REMAIN STATIONARY OVER NORTHERN LAKE SUPERIOR. ISENTROPIC ASCENT AND SHORTWAVE ENERGY WILL CONTINUE TO GENERATE A CHANCE OF SOME SHOWERS AND THUNDERSTORMS. Q-VECTOR ANALYSIS SUGGEST THAT THE MOST UNSTABLE AIR WILL BE ALONG THE CANADIAN FRONTAL SYSTEM. THE MID LEVEL LOW WILL REMAIN NEARLY STATIONARY NEAR KBIS...WITH A NUMBER OF WEAK SHORTWAVES ROTATING AROUND THIS LOW ON THURSDAY AND THURSDAY NIGHT. THE SURFACE LOW WILL ALSO BE PULLED NORTHWEST TO THE NORTH SIDE OF THE MID LEVEL LOW AND MOVE INTO NORTH CENTRAL NORTH DAKOTA. THE CANADIAN FRONTAL SYSTEM WILL REMAIN OVER CENTRAL ONTARIO. A WEAK SHORTWAVE BEING EJECTED OUT AHEAD OF THE OF MID LEVEL LOW WILL ATTEMPT TO TRAVERSE THE FORECAST AREA GENERATING A CHANCE OF SHOWERS AND THUNDERSTORMS. AS THE LOW BACKS WEST...THE ISENTROPIC ASCENT WILL ALSO WEAKEN...BUT STILL APPEARS TO BE STRONG ENOUGH TO KEEP A CHANCE OF THUNDERSTORMS GOING ESPECIALLY COUPLED WITH AFTERNOON HEATING. GUIDANCE SHOWING SURFACE DEW POINTS WILL BE HIGH ENOUGH TO PRODUCE FOG OVER THE COOL WATERS OF LAKE SUPERIOR. THE MID LEVEL RIDGE WILL START TO BREAK DOWN ON FRIDAY ALLOWING THE MID LEVEL LOW TO TREK EAST TO NEAR KJMS. THE SURFACE LOW WILL LINE UP WITH THE MID LEVEL LOW ALLOWING THE PLAINS FRONTAL SYSTEM TO MOVE INTO WESTERN IOWA. THE CANADIAN FRONT SYSTEM WILL LIKEWISE REMAIN WEAK AND OVER THE NORTHERN LAKE SUPERIOR. SHOWERS AND THUNDERSTORMS WILL CONTINUE TO BE A REAL POSSIBILITY. CURRENT GRIDS LOOK OK FOR NOW. && .MARINE (FOR 4 PM ISSUANCE OF LAKE SUPERIOR FCST)... EXPECT HIGH PRES OVER LAKE ONTARIO TO DRIFT OFF THE MID ATLANTIC COAST ON THU WHILE A LOW PRES JUST S OF LAKE WINNIPEG THIS MORNING MEANDERS SLOWLY TO THE E. THIS LOW WILL GRADUALLY PUSH INTO THE UPPER GREAT LAKES THROUGH THE WEEKEND AND WEAKEN. WINDS OVER THE LK TDAY WL RESPOND TO LK BREEZE CIRCULATION TDAY AFT MOSTLY DECOUPLED NOCTURNAL LLJ WEAKENS. LLJ TNGT WL NOT BE AS STRG WITH LACK OF PRES FALL CENTER ACRS ONTARIO. OTRW...FOLLOWED CNDN MODEL PER NCEP PREFERENCE FOR WINDS THRU THE REST OF THE WEEK. THIS MODEL IS QUITE A BIT SLOWER TO PUSH SFC LO E THAN INDICATED BY PREVIOUS GUIDANCE. CNDN SOLN PROMISES A WEAK PRES GRADIENT...SO WINDS WL BE ON THE LGT SIDE AND RESPOND TO LK BREEZE CIRCULATIONS IN THE DAY. FOG SHOULD BECOME AN ISSUE TUE NIGHT THRU THU ONCE SOME RAINFALL OCCURS OVER THE LAKE AND MOISTENS THE CHILLY MARINE LYR UNDER SHARP INVRN. && .AVIATION (FOR 06Z TAFS)... MAINTAINED MENTION OF LLWS DURING THE OVERNGT AS MQT VWP/STANNARD ROCK OBS SUGS SHARP GRADIENT OF WIND SPEED THRU NOCTURNAL INVRN UNDER STRENGTHENING LLJ. INCLUDED PROB30 GROUPS FOR SHRA BEYOND 18Z TUE AS INCREASING LOW-LEVEL MOISTURE AND AFTERNOON HEATING WILL LEAD TO GREATER INSTABILITY OVER THE AREA. OTRW...RELATIVE DRYNESS OF THE LLVLS WL MAINTAIN VFR CONDITIONS THRU THE FCST PD EXCEPT PSBLY UNDER ANY SHOWER. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...DLG MARINE/AVIATION...KC mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 125 AM EDT TUE MAY 29 2007 .DISCUSSION (ISSUED AT 420 PM)... .SHORT TERM (TONIGHT/TUE)... MAIN FCST CONCERN IS POTENTIAL OF CONVECTION...MAINLY TUE AFTN. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A MIDLEVEL RIDGE PROGRESSING E ACROSS THE UPPER MISSISSIPPI VALLEY AND ONTARIO BTWN A COUPLE OF STRONG SHORTWAVES...ONE OVER THE NRN ROCKIES AND THE OTHER OVER QUEBEC. AT THE SFC...THE MIDLEVEL RIDGE IS SUPPORTING SFC HIGH PRES OVER THE CNTRL GREAT LAKES. RETURN FLOW ON BACKSIDE OF HIGH HAS RESULTED IN A BAND OF MID CLOUDS FROM NE MN ACROSS WRN UPPER MI INTO NRN WI. SHRA AND EVEN A FEW TSRA OVER CNTRL MN EARLIER TODAY HAVE LIFTED INTO THE ARROWHEAD OF MN AND HAVE WEAKENED. PCPN WAS OCCURRING ALONG A TIGHT GRADIENT OF 850MB THETA-E WHERE FAIRLY SHARP THETA-E ADVECTION WAS BEING MAXIMIZED. LOW-MID LEVEL FRONTOGENESIS WAS ALSO PLAYING A ROLE. MIDLEVEL RIDGE AXIS WILL DRIFT OVER UPPER MI TONIGHT WITH 500MB HEIGHT RISES AROUND 30M. WITH HEIGHT RISES...NO SHORTWAVES MOVING ACROSS THE AREA AND NOSE OF LOW-LEVEL JET FOCUSING TO THE NW AND N OF FCST AREA...SEE LITTLE REASON TO INCLUDE POPS TONIGHT. AXIS OF LOW-LEVEL JET DOES SHIFT INTO WRN UPPER MI LATE WITH ELEVATED CAPE UPWARDS OF A COUPLE HUNDRED J/KG...WHICH COULD RESULT IN ISOLATED SHRA/TSRA DEVELOPING. FOR NOW...WILL LEAVE MENTION OUT AS GFS FCST SOUNDINGS INDICATE CIN WILL BE SUFFICIENT TO PREVENT CONVECTION. AS FOR TEMPS...MOS GUIDANCE LOOKS REASONABLE FOR SRLY FLOW...BEING WARMEST W AROUND 60F AND COOLEST SE AROUND 50F. ON TUE...NAM/GFS ARE IN GOOD AGREEMENT SHOWING MLCAPE INCREASING TO 500 TO POSSIBLY UPWARDS OF 1000J/KG OVER ROUGHLY THE W HALF OF UPPER MI TO THE W OF THE AREA STABILIZED BY LAKE MICHIGAN MARINE LAYER IN SRLY FLOW. MODIFYING A FEW FCST SOUNDINGS OVER THE W FOR EXPECTED SFC T/TD AROUND 80/UPPER 50S YIELDS A LITTLE LESS SBCAPE THAN MODEL MLCAPE. IN ANYCASE...LOOKS LIKE CONDITIONS WILL BE FAVORABLE FOR SOME AFTN CONVECTION. ATTM...COVERAGE LOOKS LIMITED BY LACK OF ANY SHORTWAVES OR OTHER FOCUSING MECHANISMS. SO...WILL RETAIN MID TO LOW RANGE CHC POPS MAINLY IN THE AFTN...ROUGHLY W OF A MENOMINEE TO MUNISING LINE. AREAS TO THE E SHOULD BE STABILIZED BY MARINE LAYER. WITH DEEP LAYER SHEAR IN THE 15-20KT RANGE...DO NOT ANTICIPATE ANY SVR STORMS ATTM. LONG TERM (TUE NIGHT THROUGH NEXT MON)... UNFORTUNATELY NOT MUCH TO TIE CHANCES OF PCPN THROUGH MUCH OF THIS PERIOD. SO...THE DREADED LOW CHANCE OF SHOWERS AND THUNDERSTORMS EACH DAY IS THE WAY WE HAVE TO GO AT THIS POINT. IMAGINE WE WILL FIND SOME TIME FRAMES THAT WILL END UP MOSTLY DRY...BUT JUST TOO UNCERTAIN RIGHT NOW TO TRY AND PIN THAT DOWN. MARGINALLY UNSTABLE AND WEAKLY CAPPED ENVIRONMENT WILL PERSIST AT TIMES OVER CWA TUE NIGHT THROUGH AT LEAST THU. UTILIZED CHANCE POPS WITH NO ATTEMPT AT TIMING AS SEEMS LIKE THERE COULD BE SHOWERS OR THUNDERSTORMS AT ANY GIVEN TIME UNTIL FRONTAL BOUNDARY MOVES THROUGH THURSDAY. SW FLOW ALOFT AHEAD OF TROUGH OVER THE PLAINS WILL KEEP DEEP MOISTURE IN PLAY WITH PWATS RISING TO 150-200 PCT OF NORMAL. DID CONSIDER LOWERING POPS FOR WED AS INSTABILITY MINIMIZES DUE TO RATHER LARGE DEWPOINT DEPRESSIONS IN THE MID LEVELS. WARM FRONT WELL TO NORTH SHOULD BE THE MAIN FOCUS FOR PCPN...BUT AS WINDS BECOME LIGHTER THROUGH THE DAY...STILL MAY SEE POTENTIAL FOR CONVECTION TO FORM ON LOCAL LK BREEZES. RAISED TEMPS TO AROUND 80 FOR MOST AREAS SINCE THERE MAY NOT BE AS MUCH CLOUD COVER. WED COULD BE QUITE A WARM AND HUMID DAY. DECENT AGREEMENT THAT FRONTAL BOUNDARY WILL DROP ACROSS NW CWA THU AFTN THEN THROUGH REST OF AREA THU NIGHT. UPPER FLOW IS MORE PARALLEL TO FRONT SO CANNOT SAY THE TIMING IS SOLID AT THIS POINT. ONCE FRONT MOVES THROUGH DRIER AIR BEGINS TO ADVECT IN FM ONTARIO WITH DEWPOINTS LOWERING BACK BLO 50F INSTEAD OF THE UPR 50S TO AROUND 60 READINGS THAT WILL BE COMMON THROUGH THU OUT AHEAD OF THE FRONT. HAD TO KEEP PCPN IN GRIDS FRI/FRI NIGHT AS FRONT IS STILL CLOSE ENOUGH TO THE EAST TO JUSTIFY. ALSO...GOOD AGREEMENT THAT WAVE OF LOW PRES DEVELOPS ON THE FRONT AND LIFTS ACROSS PORTIONS OF CWA FRI INTO SAT AND STALLS OUT INTO SAT NIGHT. THIS SLOWER TREND WITH RAIN CHANCES EXITING CWA...FIRST ONLY SHOWN BY GFS AND UKMET A COUPLE DAYS AGO...IS NOW APPEARING IN MAJORITY OF GUIDANCE AND ENSEMBLES ...AND IS PREFERRED BY HPC. SO... KEPT POPS INTO SAT NIGHT FOR ALL CWA...THEN LINGERED A SLIGHT CHANCE OVR THE EAST CWA NEXT SUN. EXPECT MON TO BE DRY AND A BIT COOLER IN WAKE OF TROUGH PASSAGE YET GFS INDICATES WARM AIR ADVECTION RAMPS UP AGAIN JUST SW OF HERE WITH SOME QPF GENERATED OVR MN INTO NORTHERN WI. SINCE MAIN BOUNDARY IS WELL TO THE SOUTH AT THAT POINT WILL KEEP IT DRY. && .MARINE (FOR 4 PM ISSUANCE OF LAKE SUPERIOR FCST)... HIGH PRES OVER THE CENTRAL GREAT LAKES WILL REACH THE MID ATLANTIC COAST BY TUE EVENING WHILE A LOW PRES TROF DRIFTS TO NW MN. NOCTURNAL STRENGTHENING OF LOW-LEVEL JET BTWN THESE 2 SYSTEMS TONIGHT WILL CAUSE A MODEST INCREASE IN SRLY WINDS OVER THE E HALF OF LAKE SUPERIOR...GENERALLY IN THE 15-20KT RANGE WITH 20-25KT AT TIMES ON HIGHER OBS PLATFORMS. OVER THE W HALF...SRLY WINDS ARE ALWAYS LIGHTER THAN THE E HALF IN HIGHLY STABLE ENVIRONMENTS WITH WINDS TENDING TO REMAIN MORE BACKED TO AN ERLY DIRECTION... ESPECIALLY NEAR THE MN SHORE. THIS IS REFLECTED IN THE FCST. MORE THAN LIKELY...THESE CONDITIONS WILL PERSIST OVER THE W PORTION OF THE LAKE THRU TUE. ALTHOUGH WINDS MAY DIMINISH SLIGHTLY OVER ERN LAKE SUPERIOR TUE...WILL NEED TO WATCH AREAS CLOSE TO SHORE FROM PICTURED ROCKS EWD (ESPECIALLY GRAND MARAIS AREA) FOR HIGHER WINDS AS SRLY FLOW IS OFTEN ENHANCED BY THE TERRAIN THERE. WINDS WILL TREND LIGHTER WED THRU THE END OF THE WEEK AS FRONTAL SYSTEM AND WEAK PRES GRADIENT SETTLE OVER THE AREA. FOG SHOULD BECOME AN ISSUE TUE NIGHT THRU THU ONCE SOME RAINFALL OCCURS OVER THE LAKE. && .AVIATION (FOR 06Z TAFS)... MAINTAINED MENTION OF LLWS DURING THE OVERNGT AS MQT VWP/STANNARD ROCK OBS SUGS SHARP GRADIENT OF WIND SPEED THRU NOCTURNAL INVRN UNDER STRENGTHENING LLJ. INCLUDED PROB30 GROUPS FOR SHRA BEYOND 18Z TUE AS INCREASING LOW-LEVEL MOISTURE AND AFTERNOON HEATING WILL LEAD TO GREATER INSTABILITY OVER THE AREA. OTRW...RELATIVE DRYNESS OF THE LLVLS WL MAINTAIN VFR CONDITIONS THRU THE FCST PD EXCEPT PSBLY UNDER ANY SHOWER. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM/MARINE...ROLFSON LONG TERM...JLA AVIATION...KC mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 701 PM EDT MON MAY 28 2007 .SHORT TERM (TONIGHT/TUE)... MAIN FCST CONCERN IS POTENTIAL OF CONVECTION...MAINLY TUE AFTN. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A MIDLEVEL RIDGE PROGRESSING E ACROSS THE UPPER MISSISSIPPI VALLEY AND ONTARIO BTWN A COUPLE OF STRONG SHORTWAVES...ONE OVER THE NRN ROCKIES AND THE OTHER OVER QUEBEC. AT THE SFC...THE MIDLEVEL RIDGE IS SUPPORTING SFC HIGH PRES OVER THE CNTRL GREAT LAKES. RETURN FLOW ON BACKSIDE OF HIGH HAS RESULTED IN A BAND OF MID CLOUDS FROM NE MN ACROSS WRN UPPER MI INTO NRN WI. SHRA AND EVEN A FEW TSRA OVER CNTRL MN EARLIER TODAY HAVE LIFTED INTO THE ARROWHEAD OF MN AND HAVE WEAKENED. PCPN WAS OCCURRING ALONG A TIGHT GRADIENT OF 850MB THETA-E WHERE FAIRLY SHARP THETA-E ADVECTION WAS BEING MAXIMIZED. LOW-MID LEVEL FRONTOGENESIS WAS ALSO PLAYING A ROLE. MIDLEVEL RIDGE AXIS WILL DRIFT OVER UPPER MI TONIGHT WITH 500MB HEIGHT RISES AROUND 30M. WITH HEIGHT RISES...NO SHORTWAVES MOVING ACROSS THE AREA AND NOSE OF LOW-LEVEL JET FOCUSING TO THE NW AND N OF FCST AREA...SEE LITTLE REASON TO INCLUDE POPS TONIGHT. AXIS OF LOW-LEVEL JET DOES SHIFT INTO WRN UPPER MI LATE WITH ELEVATED CAPE UPWARDS OF A COUPLE HUNDRED J/KG...WHICH COULD RESULT IN ISOLATED SHRA/TSRA DEVELOPING. FOR NOW...WILL LEAVE MENTION OUT AS GFS FCST SOUNDINGS INDICATE CIN WILL BE SUFFICIENT TO PREVENT CONVECTION. AS FOR TEMPS...MOS GUIDANCE LOOKS REASONABLE FOR SRLY FLOW...BEING WARMEST W AROUND 60F AND COOLEST SE AROUND 50F. ON TUE...NAM/GFS ARE IN GOOD AGREEMENT SHOWING MLCAPE INCREASING TO 500 TO POSSIBLY UPWARDS OF 1000J/KG OVER ROUGHLY THE W HALF OF UPPER MI TO THE W OF THE AREA STABILIZED BY LAKE MICHIGAN MARINE LAYER IN SRLY FLOW. MODIFYING A FEW FCST SOUNDINGS OVER THE W FOR EXPECTED SFC T/TD AROUND 80/UPPER 50S YIELDS A LITTLE LESS SBCAPE THAN MODEL MLCAPE. IN ANYCASE...LOOKS LIKE CONDITIONS WILL BE FAVORABLE FOR SOME AFTN CONVECTION. ATTM...COVERAGE LOOKS LIMITED BY LACK OF ANY SHORTWAVES OR OTHER FOCUSING MECHANISMS. SO...WILL RETAIN MID TO LOW RANGE CHC POPS MAINLY IN THE AFTN...ROUGHLY W OF A MENOMINEE TO MUNISING LINE. AREAS TO THE E SHOULD BE STABILIZED BY MARINE LAYER. WITH DEEP LAYER SHEAR IN THE 15-20KT RANGE...DO NOT ANTICIPATE ANY SVR STORMS ATTM. LONG TERM (TUE NIGHT THROUGH NEXT MON)... UNFORTUNATELY NOT MUCH TO TIE CHANCES OF PCPN THROUGH MUCH OF THIS PERIOD. SO...THE DREADED LOW CHANCE OF SHOWERS AND THUNDERSTORMS EACH DAY IS THE WAY WE HAVE TO GO AT THIS POINT. IMAGINE WE WILL FIND SOME TIME FRAMES THAT WILL END UP MOSTLY DRY...BUT JUST TOO UNCERTAIN RIGHT NOW TO TRY AND PIN THAT DOWN. MARGINALLY UNSTABLE AND WEAKLY CAPPED ENVIRONMENT WILL PERSIST AT TIMES OVER CWA TUE NIGHT THROUGH AT LEAST THU. UTILIZED CHANCE POPS WITH NO ATTEMPT AT TIMING AS SEEMS LIKE THERE COULD BE SHOWERS OR THUNDERSTORMS AT ANY GIVEN TIME UNTIL FRONTAL BOUNDARY MOVES THROUGH THURSDAY. SW FLOW ALOFT AHEAD OF TROUGH OVER THE PLAINS WILL KEEP DEEP MOISTURE IN PLAY WITH PWATS RISING TO 150-200 PCT OF NORMAL. DID CONSIDER LOWERING POPS FOR WED AS INSTABILITY MINIMIZES DUE TO RATHER LARGE DEWPOINT DEPRESSIONS IN THE MID LEVELS. WARM FRONT WELL TO NORTH SHOULD BE THE MAIN FOCUS FOR PCPN...BUT AS WINDS BECOME LIGHTER THROUGH THE DAY...STILL MAY SEE POTENTIAL FOR CONVECTION TO FORM ON LOCAL LK BREEZES. RAISED TEMPS TO AROUND 80 FOR MOST AREAS SINCE THERE MAY NOT BE AS MUCH CLOUD COVER. WED COULD BE QUITE A WARM AND HUMID DAY. DECENT AGREEMENT THAT FRONTAL BOUNDARY WILL DROP ACROSS NW CWA THU AFTN THEN THROUGH REST OF AREA THU NIGHT. UPPER FLOW IS MORE PARALLEL TO FRONT SO CANNOT SAY THE TIMING IS SOLID AT THIS POINT. ONCE FRONT MOVES THROUGH DRIER AIR BEGINS TO ADVECT IN FM ONTARIO WITH DEWPOINTS LOWERING BACK BLO 50F INSTEAD OF THE UPR 50S TO AROUND 60 READINGS THAT WILL BE COMMON THROUGH THU OUT AHEAD OF THE FRONT. HAD TO KEEP PCPN IN GRIDS FRI/FRI NIGHT AS FRONT IS STILL CLOSE ENOUGH TO THE EAST TO JUSTIFY. ALSO...GOOD AGREEMENT THAT WAVE OF LOW PRES DEVELOPS ON THE FRONT AND LIFTS ACROSS PORTIONS OF CWA FRI INTO SAT AND STALLS OUT INTO SAT NIGHT. THIS SLOWER TREND WITH RAIN CHANCES EXITING CWA...FIRST ONLY SHOWN BY GFS AND UKMET A COUPLE DAYS AGO...IS NOW APPEARING IN MAJORITY OF GUIDANCE AND ENSEMBLES ...AND IS PREFERRED BY HPC. SO... KEPT POPS INTO SAT NIGHT FOR ALL CWA...THEN LINGERED A SLIGHT CHANCE OVR THE EAST CWA NEXT SUN. EXPECT MON TO BE DRY AND A BIT COOLER IN WAKE OF TROUGH PASSAGE YET GFS INDICATES WARM AIR ADVECTION RAMPS UP AGAIN JUST SW OF HERE WITH SOME QPF GENERATED OVR MN INTO NORTHERN WI. SINCE MAIN BOUNDARY IS WELL TO THE SOUTH AT THAT POINT WILL KEEP IT DRY. && .MARINE (FOR 4 PM ISSUANCE OF LAKE SUPERIOR FCST)... HIGH PRES OVER THE CENTRAL GREAT LAKES WILL REACH THE MID ATLANTIC COAST BY TUE EVENING WHILE A LOW PRES TROF DRIFTS TO NW MN. NOCTURNAL STRENGTHENING OF LOW-LEVEL JET BTWN THESE 2 SYSTEMS TONIGHT WILL CAUSE A MODEST INCREASE IN SRLY WINDS OVER THE E HALF OF LAKE SUPERIOR...GENERALLY IN THE 15-20KT RANGE WITH 20-25KT AT TIMES ON HIGHER OBS PLATFORMS. OVER THE W HALF...SRLY WINDS ARE ALWAYS LIGHTER THAN THE E HALF IN HIGHLY STABLE ENVIRONMENTS WITH WINDS TENDING TO REMAIN MORE BACKED TO AN ERLY DIRECTION... ESPECIALLY NEAR THE MN SHORE. THIS IS REFLECTED IN THE FCST. MORE THAN LIKELY...THESE CONDITIONS WILL PERSIST OVER THE W PORTION OF THE LAKE THRU TUE. ALTHOUGH WINDS MAY DIMINISH SLIGHTLY OVER ERN LAKE SUPERIOR TUE...WILL NEED TO WATCH AREAS CLOSE TO SHORE FROM PICTURED ROCKS EWD (ESPECIALLY GRAND MARAIS AREA) FOR HIGHER WINDS AS SRLY FLOW IS OFTEN ENHANCED BY THE TERRAIN THERE. WINDS WILL TREND LIGHTER WED THRU THE END OF THE WEEK AS FRONTAL SYSTEM AND WEAK PRES GRADIENT SETTLE OVER THE AREA. FOG SHOULD BECOME AN ISSUE TUE NIGHT THRU THU ONCE SOME RAINFALL OCCURS OVER THE LAKE. && .AVIATION (FOR 00Z TAFS)... EXPECT SOME MID-LVL WARM AIR ADVECTION CLOUDS TO SPREAD IN FROM THE WEST TONIGHT BUT VFR CONDITIONS WILL PREVAIL. INCLUDED WIND SHEAR IN AT BOTH LOCATIONS FM 06-14Z ALTHOUGH IT WILL BE MARGINAL FOR REACHING CRITERIA AS BEST LOW-LVL WIND CORE WILL REMAIN W OF THE CWFA. INCLUDED PROB30 GROUPS FOR SHRA BEYOND 18Z TUE AS INCREASING LOW-LEVEL MOISTURE AND AFTERNOON HEATING WILL LEAD TO GREATER INSTABILITY OVER THE AREA. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM/MARINE...ROLFSON LONG TERM...JLA AVIATION...JV mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 205 PM EDT MON MAY 28 2007 .AVIATION (FOR 18Z TAFS)... EXPECT VFR CONDITIONS TO PREVAIL TODAY WITH DRY AIR AND HIGH PRES OVERHEAD. DIURNAL CU FORMED LATE IN THE MORNING...BUT HAVE SINCE DISSIPATED. LAKE BREEZES HAVE DEVELOPED WITH THE WEAK PRESSURE GRADIENT. EXPECT THE LAKE MICHIGAN ONE TO MAKE IT TO KSAW...BUT DO NOT EXPECT THE LAKE SUPERIOR ONE. WAA ADVECTION PATTERN SETTLES IN OVERNIGHT AND TOMORROW...BRINGING MIDLEVEL CLOUDS AS EARLY AS THIS AFTERNOON. THERE IS A POSSIBILITY OF MARGINAL WIND SHEAR IN BOTH LOCATIONS 08-12Z...BUT DID NOT MENTION IT DUE TO THE UNCERTAINTY IN REACHING CRITERIA. SHRA/TSRA MAY BECOME AN ISSUE JUST BEYOND THIS TAF PERIOD AS INSTABILITY BUILDS TUE AFTN. && .UPDATE (ISSUED AT 1119 AM EDT)... MAIN FCST ISSUE THIS AFTN REVOLVES AROUND INCOMING CLOUD DECK AND POSSIBLE SHRA FROM WSW. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A MIDLEVEL RIDGE PROGRESSING E ACROSS THE NRN PLAINS/MANITOBA BTWN A COUPLE OF STRONG SHORTWAVES...ONE OVER THE NRN ROCKIES AND THE OTHER OVER QUEBEC. AT THE SFC...MIDLEVEL RIDGE IS SUPPORTING SFC HIGH PRES OVER THE WRN GREAT LAKES. RETURN FLOW IS SETTING UP JUST TO THE W...RESULTING IN A BAND OF MID CLOUDS FROM NW MN TO SRN WI. A FEW SHRA ARE INDICATED BY RADARS/SFC OBS IN CNTRL MN WITH EVEN SOME TSRA IN WCNTRL MN. A LITTLE SURPRISED BY THE COVERAGE GIVEN WIMPY 20-25KT LOW-LEVEL JET (PER PROFILERS/12Z RAOBS) AND POOR MIDLEVEL LAPSE RATES. HOWEVER... THERE IS A TIGHT GRADIENT OF 850MB THETA-E...RESULTING IN FAIRLY SHARP THETA-E ADVECTION WHERE SHRA ARE OCCURRING...AND THERE IS ALSO LOW-MID LEVEL FRONTOGENESIS. 12Z RUC SHOWS BEST THETA-E ADVECTION/MOISTURE ADVECTION SHIFTING MORE N THRU MN RATHER THAN E INTO UPPER MI THIS AFTN. GIVEN THE LACK OF STRONG MOISTURE ADVECTION IN THE BOUNDARY LAYER...DRY LOW-LEVELS INDICATED BY 12Z KGRB SOUNDING WILL PROBABLY HOLD THRU THE AFTN ACROSS UPPER MI. SO...WILL PROBABLY JUST SEE A MID CLOUD DECK SLIDE E INTO THE FCST AREA THIS AFTN IN CONJUNCTION WITH WAA/ISENTROPIC ASCENT. GIVEN PROXIMITY OF STRONGER MOISTURE ADVECTION...WILL OBVIOUSLY NEED TO MONITOR TRENDS OF ONGOING SHRA W OF KDLH OVER THE NEXT FEW HRS TO SEE IF THEY MAY IN FACT BRUSH THE FAR W FCST AREA. && .PREV DISCUSSION (ISSUED AT 409 AM EDT)... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL THUNDERSTORMS ON TUESDAY. WATER VAPOR IMAGERY AND RUC SHOW A CLOSED LOW JUST SOUTHEAST OF JAMES BAY...A BROAD RIDGE OVER MANITOBA...AND ANOTHER CLOSED LOW OVER SOUTHEAST WASHINGTON STATE. WEAK SHORTWAVES ARE WORKING THROUGH THE RIDGE AND ARE OVER EASTERN U.P...THE LAKE OF THE WOOD AREA OF MINNESOTA...AND OVER SOUTHWEST MANITOBA. SURFACE ANALYSIS DEPICTS A LOW OVER CENTRAL QUEBEC...WITH A FRONTAL SYSTEM STRETCHING FROM IT THROUGH THE OHIO RIVER VALLEY TO A LOW OVER NORTHEAST WYOMING. ANOTHER LOW IS OVER CENTRAL SASKATCHEWAN. A WEAK SURFACE RIDGE IS OVER THE UPPER GREAT LAKES AND WESTERN ONTARIO. THE MID LEVEL LOW OVER WESTERN QUEBEC WILL MOVE TO EAST CENTRAL QUEBEC...THE RIDGE OVER MANITOBA WILL MOVE TO WESTERN ONTARIO...AND THE LOW OVER WASHINGTON WILL CLIMB INTO THE SASKATCHEWAN TODAY. THE SHORTWAVE OVER EASTERN U.P. WILL RACE THROUGH THE LOWER GREAT LAKES WHILE THE LAKE OF THE WOODS SHORTWAVE MOVES INTO THE WESTERN U.P. MEANWHILE...THE SURFACE HIGH OVER THE UPPER GREAT LAKES WILL SHIFT OVER THE LOWER GREAT LAKES. THE OHIO RIVER VALLEY FRONTAL SYSTEM WILL REMAIN STATIONARY AS THE LOW OVER WYOMING MOVES INTO THE NEBRASKA PANHANDLE AND THE BLACK HILLS AREA. THE SASKATCHEWAN LOW WILL SHIFT ONLY INTO EAST CENTRAL SASKATCHEWAN. THE SURFACE DEW POINTS WILL REMAIN IN THE UPPER 30S TO LOW 40S ACROSS THE AREA TODAY. THE DRY AIR AND FAIRLY STABLE CONDITIONS WILL HOLD OFF ANY PRECIPITATION TODAY. HOWEVER...THE SHORTWAVE MOVING INTO THE WESTERN U.P. WILL PRODUCE SOME CLOUDS. THE MID LEVEL RIDGE OVER WESTERN ONTARIO WILL REMAIN TONIGHT...WHILE THE SASKATCHEWAN LOW DIGS INTO NORTHEAST MONTANA. THE WEAK SHORTWAVE OVER THE WESTERN U.P. WILL RACE ACROSS THE FORECAST AREA THIS EVENING. SHORTWAVES TRACKING OVER THE RIDGE WILL NAVIGATE OVER THE RIDGE AND STAY NORTH OF THE FORECAST AREA. THE SURFACE HIGH WILL MOVE INTO THE LOWER GREAT LAKES...WHILE THE SURFACE LOW SETTLE OUT OF THE MANITOBA INTO NORTHEAST NORTH DAKOTA AND THE NEBRASKA LOW SETTLES INTO WESTERN KANSAS. QG FRONTOGENESIS FAVOR A COLD FRONT DEVELOPING BETWEEN THESE LOWS. PLAN TO KEEP CONDITIONS DRY OVER THE FORECAST AREA FOR NOW AS DEEP MOISTURE WILL STAY WEST OF THE FORECAST AREA...AND SURFACE DEW POINT OVER THE FORECAST AREA WILL REMAIN IN THE 40S OVERNIGHT. THE MID LEVEL RIDGE WILL PUSH INTO EASTERN ONTARIO ON TUESDAY... WHILE THE MONTANA LOW WILL EDGE INTO NORTHWEST NORTH DAKOTA. A WEAK SHORTWAVE WILL APPEAR OVER NORTHERN WISCONSIN. WEAK 850-500MB Q-VECTOR CONVERGENCE WILL EDGE INTO WESTERN U.P. IN ASSOCIATION WITH THIS SHORTWAVE. THE NORTH DAKOTA SURFACE LOW WILL SHIFT INTO WEST CENTRAL ONTARIO DRAGGING THE COLD FRONT INTO MINNESOTA. ISENTROPIC ASCENT WILL INCREASE MAINLY OVER THE WESTERN U.P. A WEAK SHORTWAVE WILL SLIDE INTO NORTHERN WISCONSIN. DEEP MOISTURE WILL ALSO INCREASE A LITTLE OVER THE WEST PART OF FORECAST AREA...THUS WILL KEEP A CHANCE SHOWERS AND THUNDERSTORMS IN THE WESTERN U.P. GOING. THE MID LEVEL RIDGE WILL CONTINUE ITS EASTWARD TREK AS THE NORTHWEST NORTH DAKOTA LOW ADVANCE INTO CENTRAL NORTH DAKOTA TUESDAY NIGHT AND WEDNESDAY. A WEAK SHORTWAVE TRACKING INTO THE RIDGE WILL SWEEP THROUGH THE FORECAST AREA. DEEP MOISTURE WILL WRAP AROUND THE BACKSIDE OF THE HIGH OVER MID ATLANTIC STATES AND SPREAD INTO THE UPPER GREAT LAKES REGION. A COLD FRONT WILL HANG SOUTH FROM THIS LOW THROUGH IOWA...THEN INTO THE SOUTH CENTRAL PLAINS. AT THIS TIME THE ISENTROPIC ASCENT AND MOISTURE WILL COVER MAINLY THE WESTERN U.P. HOWEVER...MODEL ARE IN SIGNIFICANT DISAGREEMENT ON THE TRACKING SPEED OF THE LOW. THEREFORE...THERE IS ENOUGH UNCERTAINTY TO HOLD OFF ON MAKING ANY SIGNIFICANT CHANGES AT THIS TIME UNTIL I CAN CHECK THE TREND WITH THE NEXT RUN. && .MARINE...400 AM ISSUANCE OF LAKE SUPERIOR FCST EXPECT A HIGH PRES RIDGE OVER THE UPPER GREAT LAKES TO DRIFT SLOWLY E OFF THE MID ATLANTIC COAST ON WED. MEANWHILE...A LOW PRES DEVELOPING OVER SOUTHERN CANADA WILL MOVE INTO ONTARIO ON WED AND WEAKEN. NOCTURNAL STRENGTHENING OF SSW LLJ BTWN THESE TWO SYS ON TUE NGT WL CAUSE A MODERATE INCRS IN WIND SPEED...BUT STABLE MARINE LYR WL LIMIT SPEEDS. LOOK FOR ANOTHER LOW PRESSURE SYSTEM TO DEVELOP IN THE PLAINS AND MOVE NE INTO THE UPPER MIDWEST ON THU AND FRI. NO GALE FORCE WINDS EXPECTED. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ AVIATION...MRC UPDATE...ROLFSON MARINE...KC PREV DISCUSSION...DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1119 AM EDT MON MAY 28 2007 .UPDATE... MAIN FCST ISSUE THIS AFTN REVOLVES AROUND INCOMING CLOUD DECK AND POSSIBLE SHRA FROM WSW. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A MIDLEVEL RIDGE PROGRESSING E ACROSS THE NRN PLAINS/MANITOBA BTWN A COUPLE OF STRONG SHORTWAVES...ONE OVER THE NRN ROCKIES AND THE OTHER OVER QUEBEC. AT THE SFC...MIDLEVEL RIDGE IS SUPPORTING SFC HIGH PRES OVER THE WRN GREAT LAKES. RETURN FLOW IS SETTING UP JUST TO THE W...RESULTING IN A BAND OF MID CLOUDS FROM NW MN TO SRN WI. A FEW SHRA ARE INDICATED BY RADARS/SFC OBS IN CNTRL MN WITH EVEN SOME TSRA IN WCNTRL MN. A LITTLE SURPRISED BY THE COVERAGE GIVEN WIMPY 20-25KT LOW-LEVEL JET (PER PROFILERS/12Z RAOBS) AND POOR MIDLEVEL LAPSE RATES. HOWEVER... THERE IS A TIGHT GRADIENT OF 850MB THETA-E...RESULTING IN FAIRLY SHARP THETA-E ADVECTION WHERE SHRA ARE OCCURRING...AND THERE IS ALSO LOW-MID LEVEL FRONTOGENESIS. 12Z RUC SHOWS BEST THETA-E ADVECTION/MOISTURE ADVECTION SHIFTING MORE N THRU MN RATHER THAN E INTO UPPER MI THIS AFTN. GIVEN THE LACK OF STRONG MOISTURE ADVECTION IN THE BOUNDARY LAYER...DRY LOW-LEVELS INDICATED BY 12Z KGRB SOUNDING WILL PROBABLY HOLD THRU THE AFTN ACROSS UPPER MI. SO...WILL PROBABLY JUST SEE A MID CLOUD DECK SLIDE E INTO THE FCST AREA THIS AFTN IN CONJUNCTION WITH WAA/ISENTROPIC ASCENT. GIVEN PROXIMITY OF STRONGER MOISTURE ADVECTION...WILL OBVIOUSLY NEED TO MONITOR TRENDS OF ONGOING SHRA W OF KDLH OVER THE NEXT FEW HRS TO SEE IF THEY MAY IN FACT BRUSH THE FAR W FCST AREA. && .PREV DISCUSSION (ISSUED AT 409 AM EDT)... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL THUNDERSTORMS ON TUESDAY. WATER VAPOR IMAGERY AND RUC SHOW A CLOSED LOW JUST SOUTHEAST OF JAMES BAY...A BROAD RIDGE OVER MANITOBA...AND ANOTHER CLOSED LOW OVER SOUTHEAST WASHINGTON STATE. WEAK SHORTWAVES ARE WORKING THROUGH THE RIDGE AND ARE OVER EASTERN U.P...THE LAKE OF THE WOOD AREA OF MINNESOTA...AND OVER SOUTHWEST MANITOBA. SURFACE ANALYSIS DEPICTS A LOW OVER CENTRAL QUEBEC...WITH A FRONTAL SYSTEM STRETCHING FROM IT THROUGH THE OHIO RIVER VALLEY TO A LOW OVER NORTHEAST WYOMING. ANOTHER LOW IS OVER CENTRAL SASKATCHEWAN. A WEAK SURFACE RIDGE IS OVER THE UPPER GREAT LAKES AND WESTERN ONTARIO. THE MID LEVEL LOW OVER WESTERN QUEBEC WILL MOVE TO EAST CENTRAL QUEBEC...THE RIDGE OVER MANITOBA WILL MOVE TO WESTERN ONTARIO...AND THE LOW OVER WASHINGTON WILL CLIMB INTO THE SASKATCHEWAN TODAY. THE SHORTWAVE OVER EASTERN U.P. WILL RACE THROUGH THE LOWER GREAT LAKES WHILE THE LAKE OF THE WOODS SHORTWAVE MOVES INTO THE WESTERN U.P. MEANWHILE...THE SURFACE HIGH OVER THE UPPER GREAT LAKES WILL SHIFT OVER THE LOWER GREAT LAKES. THE OHIO RIVER VALLEY FRONTAL SYSTEM WILL REMAIN STATIONARY AS THE LOW OVER WYOMING MOVES INTO THE NEBRASKA PANHANDLE AND THE BLACK HILLS AREA. THE SASKATCHEWAN LOW WILL SHIFT ONLY INTO EAST CENTRAL SASKATCHEWAN. THE SURFACE DEW POINTS WILL REMAIN IN THE UPPER 30S TO LOW 40S ACROSS THE AREA TODAY. THE DRY AIR AND FAIRLY STABLE CONDITIONS WILL HOLD OFF ANY PRECIPITATION TODAY. HOWEVER...THE SHORTWAVE MOVING INTO THE WESTERN U.P. WILL PRODUCE SOME CLOUDS. THE MID LEVEL RIDGE OVER WESTERN ONTARIO WILL REMAIN TONIGHT...WHILE THE SASKATCHEWAN LOW DIGS INTO NORTHEAST MONTANA. THE WEAK SHORTWAVE OVER THE WESTERN U.P. WILL RACE ACROSS THE FORECAST AREA THIS EVENING. SHORTWAVES TRACKING OVER THE RIDGE WILL NAVIGATE OVER THE RIDGE AND STAY NORTH OF THE FORECAST AREA. THE SURFACE HIGH WILL MOVE INTO THE LOWER GREAT LAKES...WHILE THE SURFACE LOW SETTLE OUT OF THE MANITOBA INTO NORTHEAST NORTH DAKOTA AND THE NEBRASKA LOW SETTLES INTO WESTERN KANSAS. QG FRONTOGENESIS FAVOR A COLD FRONT DEVELOPING BETWEEN THESE LOWS. PLAN TO KEEP CONDITIONS DRY OVER THE FORECAST AREA FOR NOW AS DEEP MOISTURE WILL STAY WEST OF THE FORECAST AREA...AND SURFACE DEW POINT OVER THE FORECAST AREA WILL REMAIN IN THE 40S OVERNIGHT. THE MID LEVEL RIDGE WILL PUSH INTO EASTERN ONTARIO ON TUESDAY... WHILE THE MONTANA LOW WILL EDGE INTO NORTHWEST NORTH DAKOTA. A WEAK SHORTWAVE WILL APPEAR OVER NORTHERN WISCONSIN. WEAK 850-500MB Q-VECTOR CONVERGENCE WILL EDGE INTO WESTERN U.P. IN ASSOCIATION WITH THIS SHORTWAVE. THE NORTH DAKOTA SURFACE LOW WILL SHIFT INTO WEST CENTRAL ONTARIO DRAGGING THE COLD FRONT INTO MINNESOTA. ISENTROPIC ASCENT WILL INCREASE MAINLY OVER THE WESTERN U.P. A WEAK SHORTWAVE WILL SLIDE INTO NORTHERN WISCONSIN. DEEP MOISTURE WILL ALSO INCREASE A LITTLE OVER THE WEST PART OF FORECAST AREA...THUS WILL KEEP A CHANCE SHOWERS AND THUNDERSTORMS IN THE WESTERN U.P. GOING. THE MID LEVEL RIDGE WILL CONTINUE ITS EASTWARD TREK AS THE NORTHWEST NORTH DAKOTA LOW ADVANCE INTO CENTRAL NORTH DAKOTA TUESDAY NIGHT AND WEDNESDAY. A WEAK SHORTWAVE TRACKING INTO THE RIDGE WILL SWEEP THROUGH THE FORECAST AREA. DEEP MOISTURE WILL WRAP AROUND THE BACKSIDE OF THE HIGH OVER MID ATLANTIC STATES AND SPREAD INTO THE UPPER GREAT LAKES REGION. A COLD FRONT WILL HANG SOUTH FROM THIS LOW THROUGH IOWA...THEN INTO THE SOUTH CENTRAL PLAINS. AT THIS TIME THE ISENTROPIC ASCENT AND MOISTURE WILL COVER MAINLY THE WESTERN U.P. HOWEVER...MODEL ARE IN SIGNIFICANT DISAGREEMENT ON THE TRACKING SPEED OF THE LOW. THEREFORE...THERE IS ENOUGH UNCERTAINTY TO HOLD OFF ON MAKING ANY SIGNIFICANT CHANGES AT THIS TIME UNTIL I CAN CHECK THE TREND WITH THE NEXT RUN. && .AVIATION (FOR 12Z TAF ISSUANCE)... EXPECT VFR CONDITIONS TO PREVAIL TDAY WITH HI PRES RDG AXIS/ DRY AIRMASS OVER THE FA. LK BREEZES WL DVLP WITH SLACK PRES GRADIENT. EXPECT MID CLD TO RETURN THIS AFTN/TNGT IN ADVANCE OF RETURNING WARM FNT...BUT DRYNESS OF AIRMASS IN PLACE SHOULD PRECLUDE LOWER CIGS/ PCPN. && .MARINE...400 AM ISSUANCE OF LAKE SUPERIOR FCST EXPECT A HIGH PRES RIDGE OVER THE UPPER GREAT LAKES TO DRIFT SLOWLY E OFF THE MID ATLANTIC COAST ON WED. MEANWHILE...A LOW PRES DEVELOPING OVER SOUTHERN CANADA WILL MOVE INTO ONTARIO ON WED AND WEAKEN. NOCTURNAL STRENGTHENING OF SSW LLJ BTWN THESE TWO SYS ON TUE NGT WL CAUSE A MODERATE INCRS IN WIND SPEED...BUT STABLE MARINE LYR WL LIMIT SPEEDS. LOOK FOR ANOTHER LOW PRESSURE SYSTEM TO DEVELOP IN THE PLAINS AND MOVE NE INTO THE UPPER MIDWEST ON THU AND FRI. NO GALE FORCE WINDS EXPECTED. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...ROLFSON AVIATION/MARINE...KC PREV DISCUSSION...DLG mi AREA FORECAST DISCUSSION...UPDATED FOR AVIATION DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 725 AM EDT MON MAY 28 2007 .DISCUSSION (ISSUED AT 409 AM EDT)... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL THUNDERSTORMS ON TUESDAY. WATER VAPOR IMAGERY AND RUC SHOW A CLOSED LOW JUST SOUTHEAST OF JAMES BAY...A BROAD RIDGE OVER MANITOBA...AND ANOTHER CLOSED LOW OVER SOUTHEAST WASHINGTON STATE. WEAK SHORTWAVES ARE WORKING THROUGH THE RIDGE AND ARE OVER EASTERN U.P...THE LAKE OF THE WOOD AREA OF MINNESOTA...AND OVER SOUTHWEST MANITOBA. SURFACE ANALYSIS DEPICTS A LOW OVER CENTRAL QUEBEC...WITH A FRONTAL SYSTEM STRETCHING FROM IT THROUGH THE OHIO RIVER VALLEY TO A LOW OVER NORTHEAST WYOMING. ANOTHER LOW IS OVER CENTRAL SASKATCHEWAN. A WEAK SURFACE RIDGE IS OVER THE UPPER GREAT LAKES AND WESTERN ONTARIO. THE MID LEVEL LOW OVER WESTERN QUEBEC WILL MOVE TO EAST CENTRAL QUEBEC...THE RIDGE OVER MANITOBA WILL MOVE TO WESTERN ONTARIO...AND THE LOW OVER WASHINGTON WILL CLIMB INTO THE SASKATCHEWAN TODAY. THE SHORTWAVE OVER EASTERN U.P. WILL RACE THROUGH THE LOWER GREAT LAKES WHILE THE LAKE OF THE WOODS SHORTWAVE MOVES INTO THE WESTERN U.P. MEANWHILE...THE SURFACE HIGH OVER THE UPPER GREAT LAKES WILL SHIFT OVER THE LOWER GREAT LAKES. THE OHIO RIVER VALLEY FRONTAL SYSTEM WILL REMAIN STATIONARY AS THE LOW OVER WYOMING MOVES INTO THE NEBRASKA PANHANDLE AND THE BLACK HILLS AREA. THE SASKATCHEWAN LOW WILL SHIFT ONLY INTO EAST CENTRAL SASKATCHEWAN. THE SURFACE DEW POINTS WILL REMAIN IN THE UPPER 30S TO LOW 40S ACROSS THE AREA TODAY. THE DRY AIR AND FAIRLY STABLE CONDITIONS WILL HOLD OFF ANY PRECIPITATION TODAY. HOWEVER...THE SHORTWAVE MOVING INTO THE WESTERN U.P. WILL PRODUCE SOME CLOUDS. THE MID LEVEL RIDGE OVER WESTERN ONTARIO WILL REMAIN TONIGHT...WHILE THE SASKATCHEWAN LOW DIGS INTO NORTHEAST MONTANA. THE WEAK SHORTWAVE OVER THE WESTERN U.P. WILL RACE ACROSS THE FORECAST AREA THIS EVENING. SHORTWAVES TRACKING OVER THE RIDGE WILL NAVIGATE OVER THE RIDGE AND STAY NORTH OF THE FORECAST AREA. THE SURFACE HIGH WILL MOVE INTO THE LOWER GREAT LAKES...WHILE THE SURFACE LOW SETTLE OUT OF THE MANITOBA INTO NORTHEAST NORTH DAKOTA AND THE NEBRASKA LOW SETTLES INTO WESTERN KANSAS. QG FRONTOGENESIS FAVOR A COLD FRONT DEVELOPING BETWEEN THESE LOWS. PLAN TO KEEP CONDITIONS DRY OVER THE FORECAST AREA FOR NOW AS DEEP MOISTURE WILL STAY WEST OF THE FORECAST AREA...AND SURFACE DEW POINT OVER THE FORECAST AREA WILL REMAIN IN THE 40S OVERNIGHT. THE MID LEVEL RIDGE WILL PUSH INTO EASTERN ONTARIO ON TUESDAY... WHILE THE MONTANA LOW WILL EDGE INTO NORTHWEST NORTH DAKOTA. A WEAK SHORTWAVE WILL APPEAR OVER NORTHERN WISCONSIN. WEAK 850-500MB Q-VECTOR CONVERGENCE WILL EDGE INTO WESTERN U.P. IN ASSOCIATION WITH THIS SHORTWAVE. THE NORTH DAKOTA SURFACE LOW WILL SHIFT INTO WEST CENTRAL ONTARIO DRAGGING THE COLD FRONT INTO MINNESOTA. ISENTROPIC ASCENT WILL INCREASE MAINLY OVER THE WESTERN U.P. A WEAK SHORTWAVE WILL SLIDE INTO NORTHERN WISCONSIN. DEEP MOISTURE WILL ALSO INCREASE A LITTLE OVER THE WEST PART OF FORECAST AREA...THUS WILL KEEP A CHANCE SHOWERS AND THUNDERSTORMS IN THE WESTERN U.P. GOING. THE MID LEVEL RIDGE WILL CONTINUE ITS EASTWARD TREK AS THE NORTHWEST NORTH DAKOTA LOW ADVANCE INTO CENTRAL NORTH DAKOTA TUESDAY NIGHT AND WEDNESDAY. A WEAK SHORTWAVE TRACKING INTO THE RIDGE WILL SWEEP THROUGH THE FORECAST AREA. DEEP MOISTURE WILL WRAP AROUND THE BACKSIDE OF THE HIGH OVER MID ATLANTIC STATES AND SPREAD INTO THE UPPER GREAT LAKES REGION. A COLD FRONT WILL HANG SOUTH FROM THIS LOW THROUGH IOWA...THEN INTO THE SOUTH CENTRAL PLAINS. AT THIS TIME THE ISENTROPIC ASCENT AND MOISTURE WILL COVER MAINLY THE WESTERN U.P. HOWEVER...MODEL ARE IN SIGNIFICANT DISAGREEMENT ON THE TRACKING SPEED OF THE LOW. THEREFORE...THERE IS ENOUGH UNCERTAINTY TO HOLD OFF ON MAKING ANY SIGNIFICANT CHANGES AT THIS TIME UNTIL I CAN CHECK THE TREND WITH THE NEXT RUN. && .AVIATION (FOR 12Z TAF ISSUANCE)... EXPECT VFR CONDITIONS TO PREVAIL TDAY WITH HI PRES RDG AXIS/ DRY AIRMASS OVER THE FA. LK BREEZES WL DVLP WITH SLACK PRES GRADIENT. EXPECT MID CLD TO RETURN THIS AFTN/TNGT IN ADVANCE OF RETURNING WARM FNT...BUT DRYNESS OF AIRMASS IN PLACE SHOULD PRECLUDE LOWER CIGS/ PCPN. && .MARINE...400 AM ISSUANCE OF LAKE SUPERIOR FCST EXPECT A HIGH PRES RIDGE OVER THE UPPER GREAT LAKES TO DRIFT SLOWLY E OFF THE MID ATLANTIC COAST ON WED. MEANWHILE...A LOW PRES DEVELOPING OVER SOUTHERN CANADA WILL MOVE INTO ONTARIO ON WED AND WEAKEN. NOCTURNAL STRENGTHENING OF SSW LLJ BTWN THESE TWO SYS ON TUE NGT WL CAUSE A MODERATE INCRS IN WIND SPEED...BUT STABLE MARINE LYR WL LIMIT SPEEDS. LOOK FOR ANOTHER LOW PRESSURE SYSTEM TO DEVELOP IN THE PLAINS AND MOVE NE INTO THE UPPER MIDWEST ON THU AND FRI. NO GALE FORCE WINDS EXPECTED. && .MQT WATCHES/WARNINGS/ADVISORIES... FROST ADVISORY 08Z-12Z MON MIZ002-004-005-009>012-084. && $$ AVIATION/MARINE...KC DISCUSSION...DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 409 AM EDT MON MAY 28 2007 .DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL THUNDERSTORMS ON TUESDAY. WATER VAPOR IMAGERY AND RUC SHOW A CLOSED LOW JUST SOUTHEAST OF JAMES BAY...A BROAD RIDGE OVER MANITOBA...AND ANOTHER CLOSED LOW OVER SOUTHEAST WASHINGTON STATE. WEAK SHORTWAVES ARE WORKING THROUGH THE RIDGE AND ARE OVER EASTERN U.P...THE LAKE OF THE WOOD AREA OF MINNESOTA...AND OVER SOUTHWEST MANITOBA. SURFACE ANALYSIS DEPICTS A LOW OVER CENTRAL QUEBEC...WITH A FRONTAL SYSTEM STRETCHING FROM IT THROUGH THE OHIO RIVER VALLEY TO A LOW OVER NORTHEAST WYOMING. ANOTHER LOW IS OVER CENTRAL SASKATCHEWAN. A WEAK SURFACE RIDGE IS OVER THE UPPER GREAT LAKES AND WESTERN ONTARIO. THE MID LEVEL LOW OVER WESTERN QUEBEC WILL MOVE TO EAST CENTRAL QUEBEC...THE RIDGE OVER MANITOBA WILL MOVE TO WESTERN ONTARIO...AND THE LOW OVER WASHINGTON WILL CLIMB INTO THE SASKATCHEWAN TODAY. THE SHORTWAVE OVER EASTERN U.P. WILL RACE THROUGH THE LOWER GREAT LAKES WHILE THE LAKE OF THE WOODS SHORTWAVE MOVES INTO THE WESTERN U.P. MEANWHILE...THE SURFACE HIGH OVER THE UPPER GREAT LAKES WILL SHIFT OVER THE LOWER GREAT LAKES. THE OHIO RIVER VALLEY FRONTAL SYSTEM WILL REMAIN STATIONARY AS THE LOW OVER WYOMING MOVES INTO THE NEBRASKA PANHANDLE AND THE BLACK HILLS AREA. THE SASKATCHEWAN LOW WILL SHIFT ONLY INTO EAST CENTRAL SASKATCHEWAN. THE SURFACE DEW POINTS WILL REMAIN IN THE UPPER 30S TO LOW 40S ACROSS THE AREA TODAY. THE DRY AIR AND FAIRLY STABLE CONDITIONS WILL HOLD OFF ANY PRECIPITATION TODAY. HOWEVER...THE SHORTWAVE MOVING INTO THE WESTERN U.P. WILL PRODUCE SOME CLOUDS. THE MID LEVEL RIDGE OVER WESTERN ONTARIO WILL REMAIN TONIGHT...WHILE THE SASKATCHEWAN LOW DIGS INTO NORTHEAST MONTANA. THE WEAK SHORTWAVE OVER THE WESTERN U.P. WILL RACE ACROSS THE FORECAST AREA THIS EVENING. SHORTWAVES TRACKING OVER THE RIDGE WILL NAVIGATE OVER THE RIDGE AND STAY NORTH OF THE FORECAST AREA. THE SURFACE HIGH WILL MOVE INTO THE LOWER GREAT LAKES...WHILE THE SURFACE LOW SETTLE OUT OF THE MANITOBA INTO NORTHEAST NORTH DAKOTA AND THE NEBRASKA LOW SETTLES INTO WESTERN KANSAS. QG FRONTOGENESIS FAVOR A COLD FRONT DEVELOPING BETWEEN THESE LOWS. PLAN TO KEEP CONDITIONS DRY OVER THE FORECAST AREA FOR NOW AS DEEP MOISTURE WILL STAY WEST OF THE FORECAST AREA...AND SURFACE DEW POINT OVER THE FORECAST AREA WILL REMAIN IN THE 40S OVERNIGHT. THE MID LEVEL RIDGE WILL PUSH INTO EASTERN ONTARIO ON TUESDAY... WHILE THE MONTANA LOW WILL EDGE INTO NORTHWEST NORTH DAKOTA. A WEAK SHORTWAVE WILL APPEAR OVER NORTHERN WISCONSIN. WEAK 850-500MB Q-VECTOR CONVERGENCE WILL EDGE INTO WESTERN U.P. IN ASSOCIATION WITH THIS SHORTWAVE. THE NORTH DAKOTA SURFACE LOW WILL SHIFT INTO WEST CENTRAL ONTARIO DRAGGING THE COLD FRONT INTO MINNESOTA. ISENTROPIC ASCENT WILL INCREASE MAINLY OVER THE WESTERN U.P. A WEAK SHORTWAVE WILL SLIDE INTO NORTHERN WISCONSIN. DEEP MOISTURE WILL ALSO INCREASE A LITTLE OVER THE WEST PART OF FORECAST AREA...THUS WILL KEEP A CHANCE SHOWERS AND THUNDERSTORMS IN THE WESTERN U.P. GOING. THE MID LEVEL RIDGE WILL CONTINUE ITS EASTWARD TREK AS THE NORTHWEST NORTH DAKOTA LOW ADVANCE INTO CENTRAL NORTH DAKOTA TUESDAY NIGHT AND WEDNESDAY. A WEAK SHORTWAVE TRACKING INTO THE RIDGE WILL SWEEP THROUGH THE FORECAST AREA. DEEP MOISTURE WILL WRAP AROUND THE BACKSIDE OF THE HIGH OVER MID ATLANTIC STATES AND SPREAD INTO THE UPPER GREAT LAKES REGION. A COLD FRONT WILL HANG SOUTH FROM THIS LOW THROUGH IOWA...THEN INTO THE SOUTH CENTRAL PLAINS. AT THIS TIME THE ISENTROPIC ASCENT AND MOISTURE WILL COVER MAINLY THE WESTERN U.P. HOWEVER...MODEL ARE IN SIGNIFICANT DISAGREEMENT ON THE TRACKING SPEED OF THE LOW. THEREFORE...THERE IS ENOUGH UNCERTAINTY TO HOLD OFF ON MAKING ANY SIGNIFICANT CHANGES AT THIS TIME UNTIL I CAN CHECK THE TREND WITH THE NEXT RUN. && .AVIATION (FOR 06Z TAF ISSUANCE)... EXPECT VFR CONDITIONS TO PREVAIL THRU FCST PD WITH HI PRES RDG AXIS/ DRY AIRMASS BLDG INTO THE FA. LK BREEZES WL DVLP ON MON WITH SLACK PRES GRADIENT. && .MARINE...400 AM ISSUANCE OF LAKE SUPERIOR FCST EXPECT A HIGH PRES RIDGE OVER THE UPPER GREAT LAKES TO DRIFT SLOWLY E OFF THE MID ATLANTIC COAST ON WED. MEANWHILE...A LOW PRES DEVELOPING OVER SOUTHERN CANADA WILL MOVE INTO ONTARIO ON WED AND WEAKEN. NOCTURNAL STRENGTHENING OF SSW LLJ BTWN THESE TWO SYS ON TUE NGT WL CAUSE A MODERATE INCRS IN WIND SPEED...BUT STABLE MARINE LYR WL LIMIT SPEEDS. LOOK FOR ANOTHER LOW PRESSURE SYSTEM TO DEVELOP IN THE PLAINS AND MOVE NE INTO THE UPPER MIDWEST ON THU AND FRI. NO GALE FORCE WINDS EXPECTED. && .MQT WATCHES/WARNINGS/ADVISORIES... FROST ADVISORY 08Z-12Z MON MIZ002-004-005-009>012-084. && $$ AVIATION/MARINE...KC DISCUSSION...DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 108 AM EDT MON MAY 28 2007 .AVIATION...AREAS OF MVFR CIGS OVER NORTHERN SITES /APN AND PLN/ BEFORE DAWN AS LOW LEVEL MOISTURE CONTINUES TO ROTATE AROUND BACKSIDE OF UPPER LOW OVER ONTARIO. DRIER AIR BUILDING IN FROM THE WEST FOR MONDAY WITH VFR CONDITIONS AND SCATTERED DIURNAL CUMULUS. GRADIENT WILL REMAIN WEAK WITH WINDS GENERALLY LESS THAN 10 KTS... WITH TYPICAL LAKE BREEZES AT ALL TAF SITES BY EARLY AFTERNOON. JK/JZ && .UPDATE...MAIN ISSUE OVERNIGHT WILL BE CLOUD TRENDS AND TEMPERATURES. UPPER LOW SPINNING ON WATER VAPOR IMAGERY EAST OF SUPERIOR WITH WRAP AROUND LOW LEVEL MOISTURE ROTATING ACROSS NORTHERN MICHIGAN /EVEN A FEW SPRINKLES OVER PARTS OF EASTERN UPPER THIS EVENING/. SOUTHERN AND WESTERN EDGE OF CLOUD DECK HAS QUICKLY DISSIPATED WITH SUNSET. RUC H9-H8 RH ANALYSIS SHOWS THIS TREND NICELY...WITH DRIER AIR BRINGING CLEARING TO MUCH OF NORTHERN LOWER SOUTH OF M-72. CLOUDS WILL BE MORE STUBBORN TO LEAVE AREAS FROM THE TIP OF THE MITT INTO EASTERN UPPER...WHERE LOW LEVEL MOISTURE WILL CONTINUE TO ROTATE IN ON THE BACKSIDE OF UPPER LOW. BUT EVEN THESE AREAS WILL HAVE BREAKS IN THE CLOUDS AS MOISTURE DEPTH DECREASES OVERNIGHT. TEMPS WILL BE TRICKY GIVEN CLOUD AND WIND TRENDS. UPSTREAM DEWPOINTS GENERALLY IN THE UPPER 30S/LOWER 40S...SO EVEN WITH PARTIAL CLEARING OVERNIGHT...I DON/T THINK LOWS WILL GET INTO DANGER ZONE FOR FROST. A FEW COLDER LOCATIONS MAY DIP INTO THE UPPER 30S...WITH MOST AREAS REMAINING IN THE LOWER/MIDDLE 40S. GRADIENT ALREADY RELAXING AND WINDS ARE DIMINISHING. BECAUSE OF THIS...WILL ALLOW SCA FOR NEARSHORE AREAS TO END LATER THIS EVENING. JK && .PREV DISCUSSION...ISSUED 412 PM EDT SUN MAY 27 2007... DISCUSSION...ON THE LATEST SURFACE WEATHER MAP...1005 MB LOW PRESSURE OVER SOUTHEAST ONTARIO WITH 1020 MB HIGH PRESSURE OVER IOWA. SATELLITE LOOPS AND SURFACE OBSERVATIONS SHOW BROKEN TO OVERCAST CONDITIONS COVERING EASTERN UPPER...NORTHEASTERN WISCONSIN AND NOW FAR NORTHERN LOWER. ELSEWHERE...CLEAR TO PARTLY CLOUDY CONDITIONS EXIST. WATER VAPOR LOOP SHOWS LARGE UPPER LOW CENTERED ACROSS SOUTHERN ONTARIO. THE MAIN SHORT TERM FORECAST CONCERN IS CLOUD COVER TONIGHT. LARGE UPPER LOW WILL CONTINUE TO MEANDER OFF TO THE EAST NORTHEAST TONIGHT. WRAP AROUND CLOUDS ARE FINALLY FILTERING INTO THE REGION FROM THE NORTHWEST (A LITTLE BEHIND SCHEDULE). MODELS CONTINUE THIS PROCESS FOR THE REMAINDER OF THE AFTERNOON INTO EARLY THIS EVENING BEFORE DRIER AIR ADVECTS IN OVERNIGHT. THEREFORE...CONTINUED MOSTLY CLOUDY SKIES ACROSS EASTERN UPPER (MEAN 900-700 MB RH ABOUT 90 PERCENT) AND BECOMING MOSTLY CLOUDY NORTH OF M-72 IN NORTHERN LOWER (MEAN 900-700 MB RH 70 TO 80 PERCENT) AND PARTLY CLOUDY SOUTHERN ZONES (MEAN 900-700 MB RH ONLY 50 TO 60 PERCENT). OVERNIGHT...MEAN 900-700 MB RH DROPS OFF BY ABOUT 20 PERCENT OR SO...WHICH SHOULD BE ENOUGH TO SCATTER OUT CLOUDS IN THE NORTH AND LEAD TO MOSTLY CLEAR CONDITIONS SOUTH. WINDS WILL SLOWLY DIMINISH TONIGHT BUT NOT TOTALLY DECOUPLE (REMAIN BETWEEN 5 AND 10 MPH) WHICH SHOULD LIMIT FROST POTENTIAL. STILL PRETTY CHILLY WITH LOWS IN THE UPPER 30S TO LOWER 40S EXPECTED. MEMORIAL DAY...IT LOOKS LIKE A GLORIOUS MEMORIAL DAY IS ON TAP. RIDGING AT THE SURFACE AND ALOFT BUILDS IN FROM THE WEST. VERY DRY AIR ADVECTS IN FROM THE WEST WITH MEAN 900-700 MB RH FALLING FROM BETWEEN 30 AND 50 PERCENT IN THE MORNING TO BETWEEN 20 AND 30 PERCENT IN THE AFTERNOON. THEREFORE PARTLY CLOUDY SKIES IN THE MORNING SHOULD GIVE WAY TO A MAINLY SUNNY AFTERNOON. HIGHS TOPPING OUT IN THE UPPER 60S AND LOWER 70S. WESTERLY WINDS WILL BE IN THE 5 TO 10 MPH RANGE. SULLIVAN LATER PERIODS...AMPLIFYING TROUGH OVER THE NORTHERN PLAINS...AND RIDGE ALONG THE EAST COAST WILL ALLOW MUCH WARMER CONDITIONS THROUGH MIDWEEK WITH PRECIPITATION ALSO RETURNING FOR MID WEEK AS NORTHERN PLAINS TROUGH SLOWLY TRAVERSES EASTWARD INTO THE WESTERN GREAT LAKES REGION. MONDAY NIGHT AND TUESDAY...AMPLIFYING TROUGH ACROSS THE HIGH PLAINS...AND RIDGE ACROSS THE EAST WILL ALLOW RETURN FLOW TO DEVELOP ACROSS THE GREAT LAKES REGION. THIS SETS THE STAGE FOR MILDER TEMPERATURES FOR THIS PERIOD. AS IS TYPICALLY THE CASE IN NORTHERN MICHIGAN...LOW LEVEL MOISTURE RETURN WILL BE VERY SLOW. THIS SLOW MOISTURE RETURN WILL HOLD OFF ANY PRECIPITATION UNTIL AT LEAST TUESDAY AFTERNOON. MOISTURE MAY BE SUFFICIENT SOUTH OF M-72 BY LATE AFTERNOON TO GENERATE SOME PRECIPITATION. ALSO...PARTLY SUNNY SKIES EXPECTED TUESDAY AFTERNOON...WILL BE ABLE TO GENERATE SOME SURFACE INSTABILITY. THUS...WILL THROW IN A CHANCE OF THUNDERSTORMS SOUTH OF M-72 FOR TUESDAY AFTERNOON. LOWS MONDAY NIGHT WILL REMAIN IN THE 40S...AS GRADIENT TIGHTENS UP AND MID TO HIGH LEVEL CLOUDS BEGIN TO SPREAD INTO THE AREA. HIGHS TUESDAY AFTERNOON WILL REACH WELL INTO THE 70S...APPROACHING 80 IN A FEW LOCATIONS. TUESDAY NIGHT...EXPECT A FEW SHOWERS AND THUNDERSTORMS TO PERSIST INTO THE EVENING HOURS WITH THE SURFACE INSTABILITY. HOWEVER...ONCE WE LOSE THE SUN...PRECIPITATION IS EXPECTED TO DIMINISH. WILL KEEP A CHANCE OF SHOWERS AND THUNDERSTORMS IN FOR ALL LOCATIONS UNTIL MIDNIGHT TO ACCOUNT FOR THIS ACTIVITY. AFTER MIDNIGHT...MAY SEE SOME ACTIVITY MOVE INTO THE AREA FROM THE WEST...SO WILL KEEP A CHANCE ACROSS THE WEST. WITH CLOUD COVER AND STRONGER WINDS...TEMPERATURES WILL ONLY FALL INTO THE MIDDLE TO UPPER 50S. EXTENDED (WEDNESDAY THROUGH SATURDAY)...WITH AMPLIFIED TROUGH TAKING UP RESIDENCE IN THE GREAT LAKES REGION...WILL HAVE A FAIRLY ACTIVE PERIOD OF WEATHER THROUGH THE END OF THE WEEK. SURFACE LOW WILL MOVE INTO THE WESTERN GREAT LAKES ON BY LATE WEDNESDAY...WITH A TRAILING FRONT BACK INTO THE CENTRAL PLAINS...KEEPING THE SURGE OF WARMTH AND MOISTURE ONGOING. HIGHS FOR WEDNESDAY WILL AGAIN REACH INTO THE MIDDLE TO UPPER 70S WITH SOME 80S POSSIBLE. BY WEDNESDAY AFTERNOON...SHOULD HAVE ENOUGH MOISTURE IN PLACE TO GENERATE SOME SHOWERS AND STORMS. HOWEVER...WE WILL HAVE TO DEAL WITH SOME CLOUD COVER FROM CONVECTION OUT WEST THAT MAY POTENTIALLY LIMIT LOW LEVEL INSTABILITY TO POP SOME ACTIVITY. THEN AGAIN...WE WILL GET SOME SHOWER/STORMS TO MOVE INTO THE AREA FROM WISCONSIN DURING THE DAY...TO WARRANT GOING WITH LIKELY POPS. ANY SFC HEATING WOULD BE A BONUS. WILL KEEP LIKELY POPS INTO WEDNESDAY NIGHT AS FRONT IS STILL IN THE AREA AND WILL HAVE PRECIP LINGERING INTO THE OVERNIGHT HOURS. PRECIP CHANCES CONTINUE THURSDAY AND FRIDAY AS MID/UPPER LEVEL TROUGH REMAINS OVER THE CENTRAL GREAT LAKES...SO SCATTERED SHOWERS AND THUNDERSTORMS SEEM REASONABLE. GFS/ECMWF VARY QUITE A BIT FOR THE WEEKEND...WITH THE GFS KEEPING THE TROUGH AROUND THE GREAT LAKES...AND ECMWF HAS THE TROUGH LIFTING AND RIDGING ENTERING THE PICTURE. WILL KEEP SATURDAY DRY FOR NOW AND SEE HOW THE NEXT FEW MODEL RUNS HANDLE THIS TROUGH. TEMPERATURES FOR THURSDAY ONWARD WILL BE ON THE COOLER SIDE WITH 60S TO LOWER 70S FOR HIGHS WITH THE TROUGH IN PLACE. KAS && .APX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 634 PM CDT TUE MAY 29 2007 .DISCUSSION... SHOWERS/THUNDERSTORMS CONTINUE TO INCREASE IN COVERAGE THIS AFTERNOON...AS MESOSCALE CONVECTIVE VORTEX LIFTS FROM EASTERN NEBRASKA/SOUTH DAKOTA INTO CENTRAL MINNESOTA. HIGHEST THREAT LOCALLY FOR SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING APPEARS TO BE ACROSS WEST CENTRAL MN...ROUGHLY FROM ALEXANDRIA TO MONTEVIDEO AND WESTWARD. THIS AREA IS IN CLOSE PROXIMITY TO THE SURFACE FRONT AND MCV...WHICH WAS BEGINNING TO SNEAK INTO WESTERN MINNESOTA AT 20Z. WILL NEED TO MONITOR THE EXTREME NORTHWESTERN CWA CLOSELY FOR NON-SUPERCELL TORNADOGENESIS...AS 20Z RUC/LAPS BOTH HIGHLIGHTED THAT AREA WITH A CORRELATED POCKET OF ENHANCED 0-3KM MLCAPE AND SURFACE VORTICITY. AFOREMENTIONED AREA ALSO HAS AN IMPRESSIVE AREA OF SURFACE THETA E CONVERGENCE...PER 20Z LAPS DATA. MID LEVEL LAPSE RATES ARE MARGINAL /AROUND 6.5 C/KM/ SO EXPECT ANY HAIL TO HAVE A HARD TIME REACHING SEVERE CRITERIA. THE SEVERE THREAT DIMINISHES WITH EASTWARD PROGRESSION ACROSS THE CWA...WHERE LOWER INSTABILITY IS PROGGED. OF NEXT CONCERN IS THE HEAVY RAINFALL POTENTIAL FOR TONIGHT...AS ACTIVITY BECOMES MORE WIDESPREAD ACROSS CENTRAL MN. COUPLED UPPER LEVEL JET STRUCTURE BEGINS TO SHIFT INTO THE NORTHERN PLAINS. THE ASSOCIATED DIFFERENTIAL DIVERGENCE COUPLET IS PROGGED TO SET UP OVER THE CENTRAL/EASTERN DAKOTAS...SO ANTICIPATE THE EXCESSIVE RAINFALL TO OCCUR WEST OF THE CWA. STILL EXPECT IT TO BE A GOOD SOAKER...WITH PRECIP AMOUNTS AROUND 1 INCH POSSIBLE ACROSS WESTERN MN /WHERE PWATS ARE AROUND 1.5 INCHES/. THE BLOCKING INFLUENCE OF THE STRONG EASTERN CONUS RIDGE WILL CAUSE THE UPPER LOW TO MAKE LITTLE IN THE WAY OF EASTWARD PROGRESSION OVER THE NEXT FEW DAYS. PREFER THE SLOWER ECMWF SOLUTION...WHICH YIELDS LINGERED PRECIPITATION CHANCES INTO SATURDAY. && .AVIATION.../00Z TAF ISSUANCE/ CONVECTION SPLITTING THE MSP AIRPORT WITH ACTIVITY TO THE W AND E. CONTINUED THIS TREND THROUGH THE EVENING. STORMS FOR STC FOR THE NEXT SEVERAL HOURS COULD HAVE GUSTS TO 35 KNOTS. AXN TO THE REAR OF THE MAIN CONVECTIVE EVENT AND TREND THEIR WILL BE DOWNWARD OVERNIGHT WITH CEILINGS EXPECTED TO GO BELOW 1000 FEET WITH VISIBILITIES A FEW MILES IN FOG. THIS TREND WILL ALSO FORECAST FOR RWF. RHN AND EAU WILL HAVE A FEW STORMS IN THE VICINITY THIS EVENING THEN A TREND OF MVFR CEILINGS AND VISIBILITIES EXPECTED OVERNIGHT. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ LS/RAH mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 655 AM CDT TUE MAY 29 2007 .DISCUSSION... /ISSUED AT 318 AM TUESDAY/ CLOSED UPPER LOW OVER THE NORTHERN PLAINS...WILL MEANDER OVER THE AREA THEN LIFT NORTHEAST OVER THE WESTERN GREAT LAKES REGION BY THE WEEKEND. UPSTREAM KICKER OVER THE PACIFIC NORTHWEST...EXPECTED TO PERSIST SOUTH OF NEAR ALEUTIAN. THUS...A LONG STRETCH OF UNSETTLE WEATHER IS ANTICIPATED OVER THE UPPER MIDWEST THROUGH THE REST OF WEEK. ALL LONG TERM MODELS ARE IN GENERAL AGREEMENT. THE FORECAST CHALLENGE OVER THE NEXT FEW DAYS ARE PRECIPITATION CHANCES AND QPF PRECIPITATION AMOUNTS. THE BEST CHANCE OF RAIN IS EXPECTED TO STAY MAINLY WEST OF OUR CWA THROUGH WEDNESDAY MORNING. KEPT SOME CHANCES POPS TODAY AND TONIGHT MOST AREAS. WATER VAPOR OFF THE SATELLITE IMAGERY SHOWED A MOISTURE PLUME FEEDING THE CONVECTIVE COMPLEXES OVER THE UPPER MIDWEST THIS MORNING. THIS MOISTURE PLUME CORRELATES TO THE THETA-E RIDGE AXIS EXTENDING FROM THE SOUTHERN ROCKIES...INTO CENTRAL PLAINS OVER NORTHERN MINNSOTA. AXIS SLIDES EAST OVER OUR CWA TONIGHT AND WEDNESDAY. MODEL DATA OFF THE NAM80 SHOWED PRECIP WATER VALUES INCREASING TO 1.60 BY WEDNESDAY MORNING. MODELS INDICATED THE BEST UPPER LEVEL DIFFLUENCE TO GENERATE SOME WIDESPREAD RAIN DEVELOPS LATER TONIGHT INTO WEDNESDAY. DRY WEDGE PUNCHES INTO WESTERN MINNESOTA BY THURSDAY MORNING AND PUSHING ACROSS THE ENTIRE FORECAST AREA INTO WESTERN WISCONSIN BY FRIDAY MORNING. MORE SHOWERS AND ISOLATED THUNDERSTORMS ARE EXPECTED OVER THE WEEKEND WITH UPPER LOW REMAINING WEST OF THE GREAT LAKES...ANTICIPATE THE ATMOSPHERE TO DESTABLIZE DURING THE LATE MORNING AND AFTERNOON TO HELP TRIGGER A FEW SHOWERS AND THUNDERSTORMS. && .AVIATION... /FOR 12Z TAFS/ COMPLEX FORECAST WITH SEVERAL CONCERNS. FIRST IS THREAT OF ISOLATED THUNDER THIS MORNING AS UPPER LEVEL WAVE INDICATED BY SATELLITE/RADAR/RUC ROTATES ACROSS SOUTHWEST MINNESOTA. HAVE NOTED ONLY A FEW ISOLATED LIGHTNING STRIKES WITH MAIN ACTIVITY WHICH IS FOCUSED FROM KAXN TO KSTC TO JUST NORTH OF KRWF AND SLIDING RAPIDLY NNE. EXPECT SOME LIGHT SHOWERS AT KMSP AND POSSIBLY KRNH OVER THE NEXT COUPLE HOURS. BAND OF MVFR CLOUD COVER WORKING INTO SOUTHWEST MN ATTM AND MAY IMPACT KRWF YET THIS MORNING. UPPER LEVEL WAVE LIFTS OFF TO THE NORTH BY LATE MORNING/EARLY AFTERNOON. INSTABILITY DOES BUILD ACROSS MOST OF THE AREA THIS AFTERNOON...WITH BEST INSTABILITY ACROSS WEST CENTRAL MN /KAXN-KRWF/. THIS IS LAID OUT AHEAD OF SLOW MOVING COLD FRONT WORKING TOWARDS WESTERN MINNESOTA. EXPECT NUMEROUS SHOWERS AND THUNDERSTORMS TO DEVELOP AND MOVE NNE AHEAD OF FRONT AND CONTINUE THROUGH THE NIGHT AT KAXN AND KRWF...WITH SOME EASTWARD EXPANSION TOWARDS KSTC AND KMSP THIS EVENING. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE ACROSS EAST CENTRAL MN AND FAR WEST CENTRAL WI THIS AFTERNOON. BEST CHANCES FOR SHOWERS AND THUNDERSTORMS ACROSS THIS AREA LOOK TO BE THIS EVENING AND TONIGHT. WINDS WILL ALSO BE STRONG TODAY...ESPECIALLY WITH ANY BREAKS IN THE CLOUD COVER THIS AFTERNOON. AM EXPECTING GUSTS OF 20-27 KTS. ..MDB.. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1011 AM EDT MON MAY 28 2007 .SYNOPSIS...HIGH PRESSURE OFF THE NORTH CAROLINA COAST WILL CONTINUE TO RIDGE INTO THE CAROLINAS THROUGH TONIGHT. A BACK DOOR COLD FRONT WILL APPROACH NORTHEASTERN NC ON TUESDAY. && .NEAR TERM /THROUGH TODAY/... RIDGING ALOFT AND AT THE SURFACE WILL RESULT IN ANOTHER HOT AND DRY DAY ACROSS CENTRAL NORTH CAROLINA. THE 1000-850 MB THICKNESS FROM GSO THIS MORNING OF 1392M IS ALMOST IDENTICAL TO THE PAST TWO MORNINGS. THEREFORE...TEMPS SHOULD BE VERY CLOSE TO THOSE OF THE PAST TWO DAYS. A DEGREE OR TWO MORE COULD BE SEEN IN SOME LOCATIONS AS THE LATEST RUC AND NAM GUIDANCE SUGGEST A FEW METERS RISE IN LOW LEVEL THICKNESS VALUES THIS AFTERNOON AS COMPARED TO YESTERDAY. THE CURRENT FORECAST HAS A GOOD HANDLE ON THIS AND NO CHANGES ARE NEEDED. PERIODS OF HIGH CIRRUS WILL PASS THROUGH THE AREA TODAY...VARYING THE SKY BETWEEN MOSTLY SUNNY AND PARTLY SUNNY. SOME DIURNAL CUMULUS ARE POSSIBLE...BUT THE ATMOSPHERE HAS NOT MOISTENED UP MUCH IN THE PAST FEW DAYS...SO WE ARE NOT EXPECTING AN EXPANSIVE CU FIELD TODAY. NO UPDATE TO THE ZONE FORECAST WILL BE NEEDED. THE GRIDS WILL BE UPDATED SLIGHTLY TO REFLECT CURRENT TEMP AND DEWPOINT TRENDS. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... RIDGE WEAKENS A BIT AND SHIFTS WESTWARD TONIGHT AND TUESDAY. THIS ALLOWS A BACK DOOR COLD FRONT TO SLIP SOUTH ACROSS THE MID ATLANTIC AND THEN STALL ACROSS NE NC ON TUESDAY. ORIENTATION OF THE FRONT SHIFTS FROM WEST TO EAST TO MORE NORTHWEST TO SOUTHEAST AS THE MAIN PUSH BEHIND THE FRONT DRIVES S JUST OFF THE COAST. MOS NUMBERS INDICATE LITTLE CHANCE OF PRECIP ACROSS NE AND E ZONES ON TUESDAY THROUGH WEDNESDAY. 21Z SREF SUGGEST CHANCE POPS MAY BE WARRANTED FOR TUESDAY NIGHT AND WEDNESDAY. WITH INCREASING AMOUNTS OF INSTABILITY AND CONVERGENCE...WILL ADD SLIGHT CHC POPS TO NE ZONES ON TUESDAY AFTERNOON AND EVENING. MAX TEMPS SHOULD BE A DEGREE OR TWO COOLER THAN PREVIOUS DAYS...ESPECIALLY ACROSS NE ZONES. FRONT WASHES OUT A BIT ON WEDNESDAY AND SUPPORT FOR CONVECTION DIMINISHES. INCREASING MOISTURE AND CLOUD COVER RESULT IN MAX TEMPS IN THE UPPER 80S ON WEDNESDAY. && .LONG TERM /THURSDAY THROUGH SUNDAY/... UPPER RIDGE/SURFACE HIGH WILL SHIFT FURTHER OFFSHORE THE LATTER PART OF THE WEEK AS LONG WAVE TROUGH MOVES EAST ACROSS THE CENTRAL CONUS. TIMING AND DETAILS ON THIS SYSTEMS EVENTUAL EVOLUTION REMAIN UNCLEAR. HPC GUIDANCE SUGGEST THAT BEST CHANCE OF PRECIP IS ON SAT AND SUN. && .AVIATION /14Z MONDAY THROUGH FRIDAY/... VFR CONDITIONS FOR THE TAF PERIOD. HIGH PRESSURE OFFSHORE WILL PROVIDE A LIGHT SOUTHERLY WIND. AFTERNOON CUMULUS WITH BASES AROUND 6000 FEET WILL QUICKLY DISSIPATE BY SUNSET WITH SKIES MAINLY CLEAR...WITH PERHAPS A FEW CIRRUS OVERNIGHT. VFR CONDITIONS WILL PREVAIL FOR THE NEXT SEVERAL DAYS DUE TO THE CONTINUED PRESENCE OF HIGH PRESSURE. BACK DOOR FRONT MAY BRING REDUCED CIGS TUESDAY AND WED AT KRWI. ISOLATED CONVECTION IS POSSIBLE WEDNESDAY THROUGH FRIDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...JFB SHORT TERM...BLAES LONG TERM...BLAES AVIATION...RLH nc AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 1118 PM CDT TUE MAY 29 2007 .UPDATE...CONVECTION APPROACHING WESTERNMOST PORTIONS OF WEBB COUNTY BUT STILL 40 TO 50 MILES AWAY. DECIDED TO PUT POPS IN WEBB COUNTY AFTER MIDNIGHT SHOULD SOME CONVECTION REMAIN. IF IT GETS INTO WEBB COUNTY...DO NOT EXPECT MUCH IN EASTWARD PROGRESSION SINCE SUPPORTING WINDS ARE LIGHT AND BECOME MORE SOUTHERLY. && .PREV DISCUSSION... /ISSUED 942 PM CDT TUE MAY 29 2007/ UPDATE...FORECAST FINE FOR NOW...NO CHANGES NEEDED. STILL A SLIGHT POTENTIAL FOR CONVECTION OVER OLD MEXICO TO GET INTO NORTHWEST SO WILL MAINTAIN POPS THERE. EVERYTHING ELSE FINE AND NOTHING OUT OF TOLERANCE NOW SO NO NEED TO CHANGE ANYTHING. AVIATION...CONVECTIVE DEBRIS FROM THUNDERSTORMS OVER THE SIERRA MADRE WILL STREAM OVER SOUTH TEXAS THROUGH THIS EVENING. MVFR/IFR CONDITIONS WILL DEVELOP OVER THE COASTAL PLAINS (KALI-KVCT) BETWEEN 10Z-11Z WITH CIGS/VSBYS IMPROVING TO VFR BY 16Z. VFR CONDITIONS WILL THEN PREVAIL OVER SOUTH TEXAS THROUGH WEDNESDAY NIGHT. PREV DISCUSSION... /ISSUED 307 PM CDT TUE MAY 29 2007/ SHORT TERM...SATELLITE IMAGERY SHOWS VORTICITY MAXIMUM OVER NORTH CENTRAL TEXAS. 15Z RUC MODEL SHOWS TAIL END OF VORTICITY AXIS EXTENDING TO THE SOUTHWEST INTO THE TEXAS HILL COUNTRY. MODELS KEEP THE 85H THETA-E RIDGE AXIS ALONG THE RIO GRANDE WITH SOME WEAK SURFACE TO 85H MOISTURE CONVERGENCE. AIRMASS HAS BECOME VERY UNSTABLE OVER THE WESTERN RIO GRANDE PLAINS (CAPE FROM 3000-3500 J/KG) WITH CONVECTIVE INHIBITION WEAKENING. ISOLATED CONVECTION THAT FORMS OVER THE HIGHER TERRAIN IN NORTHEAST MEXICO COULD MOVE EAST-SOUTHEAST INTO THE WESTERN COUNTIES THIS EVENING. WILL PLACE A SLIGHT CHANCE OF T-STORMS OVER THE NORTHWEST PART OF THE FORECAST AREA FOR THIS EVENING. OTHERWISE...THE MID TO UPPER LEVEL TROUGH AXIS WILL MOVE INTO THE NORTHWEST GULF OF MEXICO WEDNESDAY. SUBSIDENCE AND MID LEVEL WARMING WILL RESULT PRECLUDING ANY SIGNIFICANT RAIN CHANCES OVER THE AREA THROUGH WEDNESDAY NIGHT. LIGHT WINDS OVERNIGHT WILL LEAD TO AREAS OF FOG FORMING OVER THE INLAND COASTAL PLAINS WEDNESDAY MORNING/LATE WEDNESDAY NIGHT. AVIATION...VFR CONDITIONS WILL CONTINUE OVER THE AREA INTO THE OVERNIGHT HOURS. WITH LIGHT WINDS AND MOIST BOUNDARY LAYER CONDITIONS...EXPECT AREAS OF FOG TO FORM OVER THE INLAND COASTAL PLAINS AROUND 09Z AND CONTINUE THROUGH 14Z. AREAS OF IFR/LIFR CONDITIONS WILL BE POSSIBLE FROM ALICE NORTHEAST TO VICTORIA. MVFR VSBYS EXPECTED CLOSER TO THE COAST AND OVER PORTIONS OF THE RIO GRANDE PLAINS. BRIEF PERIOD OF MVFR CEILINGS OVER THE VICTORIA CROSSROADS WEDNESDAY MORNING...OTHERWISE VFR CONDS THRU WEDNESDAY EVENING. MARINE...BENIGN CONDITIONS WILL CONTINUE THROUGH THE PERIOD WITH A WEAK TO MODERATE SOUTHEAST WIND AND 3-4 FOOT SEAS. LONG TERM (THURSDAY THROUGH TUESDAY)...BOUNDARY LAYER MOISTURE REMAINS AT MARGINAL LEVELS THURSDAY/FRIDAY WITH THE CAPPING INVERSION IN A WEAKENED STATE(700HPA TEMPERATURES BELOW +10C). SOME WEAK MID-LEVEL ENERGY IS PRESENT BOTH DAYS BUT SYNOPTIC-SCALE SUBSIDENCE GENERALLY PREVAILS. OUTFLOW BOUNDARY FROM CONVECTION WELL TO THE NORTH MAY LEAVE A THETA-E GRADIENT INVOF THE NORTHERN CWA THURSDAY NIGHT/FRIDAY. OTHERWISE THE SEA BREEZE BOUNDARY(GREATEST DEFINITION FRIDAY) WILL BE THE SURFACE FORCING MECHANISM. WILL ONLY SHOW SLIGHT CHANCE POPS ACROSS THE NORTHEAST CWA. MOIST GROUND/STABLE BOUNDARY LAYER WILL RESULT IN LATE NIGHT/EARLY MORNING PATCHY FOG. ONLY MINOR TWEAKS TO THE PREVIOUS TEMPERATURE GRIDS. DRY/SUBSIDENT NORTHWEST FLOW ALOFT PREVAILS SATURDAY THROUGH TUESDAY. NORTHERN COUNTIES WILL BE VULNERABLE TO OUTFLOW BOUNDARIES MONDAY/TUESDAY AS WEAK QUASI-STATIONARY FRONTAL BOUNDARY ACROSS SOUTH-CENTRAL TEXAS GENERATES CONVECTION. HOWEVER...WILL ONLY INDICATE GHOST POPS AS CAPPING INVERSION WILL BE RATHER FORMIDABLE GIVEN 700HPA TEMPERATURES WELL ABOVE +10C. NO CHANGES TO THE PREVIOUS TEMPERATURE GRIDS. && .PRELIMINARY POINT TEMPS/POPS... CORPUS CHRISTI 72 90 72 86 69 / 10 10 10 10 0 VICTORIA 69 89 70 87 69 / 10 10 10 10 10 LAREDO 75 101 76 98 74 / 20 10 10 0 0 ALICE 70 94 71 90 70 / 10 10 10 10 0 ROCKPORT 74 87 74 86 73 / 10 10 10 10 0 COTULLA 72 97 71 94 72 / 10 10 10 10 10 KINGSVILLE 71 92 72 89 70 / 10 10 10 10 0 NAVY CORPUS 75 86 75 86 74 / 10 10 10 10 0 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ GW/86 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 942 PM CDT TUE MAY 29 2007 .UPDATE...FORECAST FINE FOR NOW...NO CHANGES NEEDED. STILL A SLIGHT POTENTIAL FOR CONVECTION OVER OLD MEXICO TO GET INTO NORTHWEST SO WILL MAINTAIN POPS THERE. EVERYTHING ELSE FINE AND NOTHING OUT OF TOLERANCE NOW SO NO NEED TO CHANGE ANYTHING. && .AVIATION...CONVECTIVE DEBRIS FROM THUNDERSTORMS OVER THE SIERRA MADRE WILL STREAM OVER SOUTH TEXAS THROUGH THIS EVENING. MVFR/IFR CONDITIONS WILL DEVELOP OVER THE COASTAL PLAINS (KALI-KVCT) BETWEEN 10Z-11Z WITH CIGS/VSBYS IMPROVING TO VFR BY 16Z. VFR CONDITIONS WILL THEN PREVAIL OVER SOUTH TEXAS THROUGH WEDNESDAY NIGHT. && .PREV DISCUSSION... /ISSUED 307 PM CDT TUE MAY 29 2007/ SHORT TERM...SATELLITE IMAGERY SHOWS VORTICITY MAXIMUM OVER NORTH CENTRAL TEXAS. 15Z RUC MODEL SHOWS TAIL END OF VORTICITY AXIS EXTENDING TO THE SOUTHWEST INTO THE TEXAS HILL COUNTRY. MODELS KEEP THE 85H THETA-E RIDGE AXIS ALONG THE RIO GRANDE WITH SOME WEAK SURFACE TO 85H MOISTURE CONVERGENCE. AIRMASS HAS BECOME VERY UNSTABLE OVER THE WESTERN RIO GRANDE PLAINS (CAPE FROM 3000-3500 J/KG) WITH CONVECTIVE INHIBITION WEAKENING. ISOLATED CONVECTION THAT FORMS OVER THE HIGHER TERRAIN IN NORTHEAST MEXICO COULD MOVE EAST-SOUTHEAST INTO THE WESTERN COUNTIES THIS EVENING. WILL PLACE A SLIGHT CHANCE OF T-STORMS OVER THE NORTHWEST PART OF THE FORECAST AREA FOR THIS EVENING. OTHERWISE...THE MID TO UPPER LEVEL TROUGH AXIS WILL MOVE INTO THE NORTHWEST GULF OF MEXICO WEDNESDAY. SUBSIDENCE AND MID LEVEL WARMING WILL RESULT PRECLUDING ANY SIGNIFICANT RAIN CHANCES OVER THE AREA THROUGH WEDNESDAY NIGHT. LIGHT WINDS OVERNIGHT WILL LEAD TO AREAS OF FOG FORMING OVER THE INLAND COASTAL PLAINS WEDNESDAY MORNING/LATE WEDNESDAY NIGHT. AVIATION...VFR CONDITIONS WILL CONTINUE OVER THE AREA INTO THE OVERNIGHT HOURS. WITH LIGHT WINDS AND MOIST BOUNDARY LAYER CONDITIONS...EXPECT AREAS OF FOG TO FORM OVER THE INLAND COASTAL PLAINS AROUND 09Z AND CONTINUE THROUGH 14Z. AREAS OF IFR/LIFR CONDITIONS WILL BE POSSIBLE FROM ALICE NORTHEAST TO VICTORIA. MVFR VSBYS EXPECTED CLOSER TO THE COAST AND OVER PORTIONS OF THE RIO GRANDE PLAINS. BRIEF PERIOD OF MVFR CEILINGS OVER THE VICTORIA CROSSROADS WEDNESDAY MORNING...OTHERWISE VFR CONDS THRU WEDNESDAY EVENING. MARINE...BENIGN CONDITIONS WILL CONTINUE THROUGH THE PERIOD WITH A WEAK TO MODERATE SOUTHEAST WIND AND 3-4 FOOT SEAS. LONG TERM (THURSDAY THROUGH TUESDAY)...BOUNDARY LAYER MOISTURE REMAINS AT MARGINAL LEVELS THURSDAY/FRIDAY WITH THE CAPPING INVERSION IN A WEAKENED STATE(700HPA TEMPERATURES BELOW +10C). SOME WEAK MID-LEVEL ENERGY IS PRESENT BOTH DAYS BUT SYNOPTIC-SCALE SUBSIDENCE GENERALLY PREVAILS. OUTFLOW BOUNDARY FROM CONVECTION WELL TO THE NORTH MAY LEAVE A THETA-E GRADIENT INVOF THE NORTHERN CWA THURSDAY NIGHT/FRIDAY. OTHERWISE THE SEA BREEZE BOUNDARY(GREATEST DEFINITION FRIDAY) WILL BE THE SURFACE FORCING MECHANISM. WILL ONLY SHOW SLIGHT CHANCE POPS ACROSS THE NORTHEAST CWA. MOIST GROUND/STABLE BOUNDARY LAYER WILL RESULT IN LATE NIGHT/EARLY MORNING PATCHY FOG. ONLY MINOR TWEAKS TO THE PREVIOUS TEMPERATURE GRIDS. DRY/SUBSIDENT NORTHWEST FLOW ALOFT PREVAILS SATURDAY THROUGH TUESDAY. NORTHERN COUNTIES WILL BE VULNERABLE TO OUTFLOW BOUNDARIES MONDAY/TUESDAY AS WEAK QUASI-STATIONARY FRONTAL BOUNDARY ACROSS SOUTH-CENTRAL TEXAS GENERATES CONVECTION. HOWEVER...WILL ONLY INDICATE GHOST POPS AS CAPPING INVERSION WILL BE RATHER FORMIDABLE GIVEN 700HPA TEMPERATURES WELL ABOVE +10C. NO CHANGES TO THE PREVIOUS TEMPERATURE GRIDS. && .PRELIMINARY POINT TEMPS/POPS... CORPUS CHRISTI 72 90 72 86 69 / 10 10 10 10 0 VICTORIA 69 89 70 87 69 / 10 10 10 10 10 LAREDO 75 101 76 98 74 / 10 10 10 0 0 ALICE 71 94 71 90 70 / 10 10 10 10 0 ROCKPORT 74 87 74 86 73 / 10 10 10 10 0 COTULLA 72 97 71 94 72 / 20 10 10 10 10 KINGSVILLE 71 92 72 89 70 / 10 10 10 10 0 NAVY CORPUS 75 86 75 86 74 / 10 10 10 10 0 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ TM/95...MESO/AVIATION GW/86...GRIDS/PUBLIC tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 307 PM CDT TUE MAY 29 2007 .SHORT TERM...SATELLITE IMAGERY SHOWS VORTICITY MAXIMUM OVER NORTH CENTRAL TEXAS. 15Z RUC MODEL SHOWS TAIL END OF VORTICITY AXIS EXTENDING TO THE SOUTHWEST INTO THE TEXAS HILL COUNTRY. MODELS KEEP THE 85H THETA-E RIDGE AXIS ALONG THE RIO GRANDE WITH SOME WEAK SURFACE TO 85H MOISTURE CONVERGENCE. AIRMASS HAS BECOME VERY UNSTABLE OVER THE WESTERN RIO GRANDE PLAINS (CAPE FROM 3000-3500 J/KG) WITH CONVECTIVE INHIBITION WEAKENING. ISOLATED CONVECTION THAT FORMS OVER THE HIGHER TERRAIN IN NORTHEAST MEXICO COULD MOVE EAST-SOUTHEAST INTO THE WESTERN COUNTIES THIS EVENING. WILL PLACE A SLIGHT CHANCE OF T-STORMS OVER THE NORTHWEST PART OF THE FORECAST AREA FOR THIS EVENING. OTHERWISE...THE MID TO UPPER LEVEL TROUGH AXIS WILL MOVE INTO THE NORTHWEST GULF OF MEXICO WEDNESDAY. SUBSIDENCE AND MID LEVEL WARMING WILL RESULT PRECLUDING ANY SIGNIFICANT RAIN CHANCES OVER THE AREA THROUGH WEDNESDAY NIGHT. LIGHT WINDS OVERNIGHT WILL LEAD TO AREAS OF FOG FORMING OVER THE INLAND COASTAL PLAINS WEDNESDAY MORNING/LATE WEDNESDAY NIGHT. && .AVIATION...VFR CONDITIONS WILL CONTINUE OVER THE AREA INTO THE OVERNIGHT HOURS. WITH LIGHT WINDS AND MOIST BOUNDARY LAYER CONDITIONS...EXPECT AREAS OF FOG TO FORM OVER THE INLAND COASTAL PLAINS AROUND 09Z AND CONTINUE THROUGH 14Z. AREAS OF IFR/LIFR CONDITIONS WILL BE POSSIBLE FROM ALICE NORTHEAST TO VICTORIA. MVFR VSBYS EXPECTED CLOSER TO THE COAST AND OVER PORTIONS OF THE RIO GRANDE PLAINS. BRIEF PERIOD OF MVFR CEILINGS OVER THE VICTORIA CROSSROADS WEDNESDAY MORNING...OTHERWISE VFR CONDS THRU WEDNESDAY EVENING. && .MARINE...BENIGN CONDITIONS WILL CONTINUE THROUGH THE PERIOD WITH A WEAK TO MODERATE SOUTHEAST WIND AND 3-4 FOOT SEAS. && .LONG TERM (THURSDAY THROUGH TUESDAY)...BOUNDARY LAYER MOISTURE REMAINS AT MARGINAL LEVELS THURSDAY/FRIDAY WITH THE CAPPING INVERSION IN A WEAKENED STATE(700HPA TEMPERATURES BELOW +10C). SOME WEAK MID-LEVEL ENERGY IS PRESENT BOTH DAYS BUT SYNOPTIC-SCALE SUBSIDENCE GENERALLY PREVAILS. OUTFLOW BOUNDARY FROM CONVECTION WELL TO THE NORTH MAY LEAVE A THETA-E GRADIENT INVOF THE NORTHERN CWA THURSDAY NIGHT/FRIDAY. OTHERWISE THE SEA BREEZE BOUNDARY(GREATEST DEFINITION FRIDAY) WILL BE THE SURFACE FORCING MECHANISM. WILL ONLY SHOW SLIGHT CHANCE POPS ACROSS THE NORTHEAST CWA. MOIST GROUND/STABLE BOUNDARY LAYER WILL RESULT IN LATE NIGHT/EARLY MORNING PATCHY FOG. ONLY MINOR TWEAKS TO THE PREVIOUS TEMPERATURE GRIDS. DRY/SUBSIDENT NORTHWEST FLOW ALOFT PREVAILS SATURDAY THROUGH TUESDAY. NORTHERN COUNTIES WILL BE VULNERABLE TO OUTFLOW BOUNDARIES MONDAY/TUESDAY AS WEAK QUASI-STATIONARY FRONTAL BOUNDARY ACROSS SOUTH-CENTRAL TEXAS GENERATES CONVECTION. HOWEVER...WILL ONLY INDICATE GHOST POPS AS CAPPING INVERSION WILL BE RATHER FORMIDABLE GIVEN 700HPA TEMPERATURES WELL ABOVE +10C. NO CHANGES TO THE PREVIOUS TEMPERATURE GRIDS. && .PRELIMINARY POINT TEMPS/POPS... CORPUS CHRISTI 72 90 72 86 69 / 10 10 10 10 0 VICTORIA 69 89 70 87 69 / 10 10 10 10 10 LAREDO 75 101 76 98 74 / 10 10 10 0 0 ALICE 71 94 71 90 70 / 10 10 10 10 0 ROCKPORT 74 87 74 86 73 / 10 10 10 10 0 COTULLA 72 97 71 94 72 / 20 10 10 10 10 KINGSVILLE 71 92 72 89 70 / 10 10 10 10 0 NAVY CORPUS 75 86 75 86 74 / 10 10 10 10 0 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ TMT/89...SHORT TERM BB/85...LONG TERM tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 1031 AM CDT TUE MAY 29 2007 .UPDATE...12Z CRP SOUNDING SHOWED A WEAK VEERING WIND PROFILE IN THE LOWEST 10 KFT. LATEST MSAS ANALYSIS SHOWED A CONVERGENCE ZONE OVER THE MID COAST REGION WITH A MODERATELY UNSTABLE AIRMASS IN PLACE WITH LIFTED INDEX -6 TO -7 DEGREES. ISOLATED SHOWERS HAVE DEVELOPED OVER FROM NORTH OF ROCKPORT TO PORT LAVACA. A FEW FUNNEL CLOUDS HAVE DEVELOPED WITH THE SHOWERS WITH THIS WEAK WIND PROFILE. 12Z RUC 25H STREAMLINE ANALYSIS SHOWED SOME WEAK DIFLUENCE MOVING ACROSS THE BRUSH COUNTRY TOWARD THE MID COAST REGION. LOW LEVEL CONVERGENCE ZONE SHOULD MIGRATE INLAND BY THIS AFTERNOON. RAISED POPS TO 20 PERCENT FOR THE VICTORIA CROSSROADS. NO OTHER CHANGES MADE TO THE FORECAST. && .PREV DISCUSSION... /ISSUED 326 AM CDT TUE MAY 29 2007/ SHORT TERM (TODAY THROUGH WEDNESDAY)...SUBSIDENCE WL PREVAIL THROUGH THE FCST PD AS A MEAN LYR RDG AXIS CONTINUES TO BUILD INTO THE RGN. THUS THE AIRMASS WL CONTINUE TO DRY OUT AND WARM UP. ISOLATED SEABREEZE CONVECTION WL STILL BE POSSIBLE THIS AFTN ACROSS THE NORTHEAST COASTAL BEND. WL NOT MENTION PCPN ON WED AS THE CAP STRENGTHENS AND THE AIRMASS DRIES OUT EVEN FURTHER. THE PROXIMITY TO A SFC RDG AXIS WL KEEP THE WINDS RELATIVELY WEAK. WL BE MORE OPTIMISTIC WITH THE CLOUD CVR FCST GIVEN THE DRIER WX PATTERN AND LIGHTER WINDS. AVIATION...MVFR CONDITIONS WL CONTINUE TO DEVELOP ACROSS MUCH OF THE RGN THIS MORNING. IFR CONDITIONS WL OCCUR AS WELL AND WL BE MOSTLY CONFINED TO TAF SITES SUCH AS ALI. IFR CONDITIONS WL TRANSITION TO MVFR BY 15Z TDA. MVFR CONDITIONS WL TRANSITION TO VFR CONDITIONS ACROSS MOST AREAS BY NOON AS CLOUDS GRADUALLY RISE AND THIN OUT. MVFR CONDITIONS WL ONCE AGAIN DEVELOP AFTER MIDNIGHT TNT ACROSS TAF SITES SUCH AS ALI AND VCT. LONG TERM (WEDNESDAY NIGHT THROUGH MONDAY)...REGION WILL REMAIN SANDWICHED BETWEEN AN UPPER LEVEL RIDGE OVR MEXICO AND TROF ACROSS THE SE U.S. AND NRN GULF THROUGH SAT...RESULTING IN A DRY/SUBSIDENT REGIME ACROSS S TX. MODELS ARE IN FAIR AGREEMENT WITH THIS SCENARIO THEREFORE CONFIDENCE IS GOOD THAT PRECIP WILL LIMITED TO AN ISOLATED SEA BREEZE FORCED SHRA AT BEST...BUT TOO ISOLATED TO WARRANT MENTIONING IN FCST. AGREE WITH PREVIOUS LONG TERM FORECASTER THAT MOIST SOIL FROM PREVIOUS RAINS WILL INITIALLY HINDER TEMPS FROM INCREASING. AS THE SOIL DRIES...AND SUBSIDENCE CONTINUES... A WARMING TREND CAN BE EXPECTED INTO THE WEEKEND. THE GFS PROGS THE RIDGE TO BEGIN TO BREAK DOWN BY SUN/MON AS A NRN STREAM LOW DIGS FARTHER S AND E THUS AMPLIFYING THE RIDGE FARTHER W. HOWEVER...MOISTURE WILL REMAIN LIMITED THEREFORE WILL CONTINUE WITH A DRY FCST. && .PRELIMINARY POINT TEMPS/POPS... CORPUS CHRISTI 89 71 90 72 88 / 10 0 0 10 10 VICTORIA 87 68 89 70 89 / 20 10 10 10 10 LAREDO 98 76 100 76 98 / 10 10 0 10 10 ALICE 92 70 94 71 91 / 10 0 0 10 10 ROCKPORT 87 73 87 73 87 / 20 0 0 10 10 COTULLA 91 69 93 72 94 / 10 10 0 10 10 KINGSVILLE 92 70 94 72 90 / 10 0 0 10 10 NAVY CORPUS 87 74 87 74 86 / 10 0 0 10 10 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ TMT/89...SHORT TERM BB/85...LONG TERM tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 320 AM EDT WED MAY 30 2007 .SYNOPSIS...A SFC HIGH PRESSURE SYSTEM HAS NOW SHIFTED OFFSHORE OF THE SC WATERS WITH WEAK ONSHORE FLOW CONTINUING. AS MENTIONED IN PREVIOUS DISCUSSION...LOW LEVELS ARE DRIER AS EVIDENT FROM 00Z SOUNDING WITH PWAT NEAR 0.92. LARGE RIDGE OF HIGH PRESSURE AT 500 MB IS NOTED IN RUC ANALYSIS AND WATER VAPOR IMAGERY FROM FL TO THE OHIO VALLEY. AREAS OF FOG EXPECTED MAINLY OVER GA ZONES THROUGH EARLY MORNING. .SHORT TERM...MODELS ARE SIMILAR IN SHOWING LOW PWATS TODAY MAINLY AROUND 0.75 INCHES ACROSS THE AREA WITH MOSTLY SUNNY TO PARTLY SUNNY SKIES WITH SOME CU DEVELOPMENT BUT NOT AS MUCH AS PREVIOUS DAYS. SCT-BKN HIGH CLOUDS SHOULD CONTINUE AS UPPER TROUGH OVER THE NRN GULF OF MEXICO MOVES EWD. HIGHS REBOUND FROM MORNING LOWS IN THE 60S TO AROUND 90 INLAND AND LOWER 80S AT THE COAST. LOWS TONIGHT EXPECTED TO BE MAINLY IN THE LOWER TO MID 60S WITH PATCHY FOG POSSIBLE OVER NE ZONES. THURSDAY...MODELS IN AGREEMENT INDICATING A SWATH OF SLIGHTLY HIGHER MOISTURE MOVING INTO THE REGION FROM THE ATLANTIC BY THURSDAY MORNING WITH THE POSSIBILITY AGAIN OF ISOLD SMALL SHOWERS DURING THE DAY. LITTLE CHANGE TO HIGH TEMPS FROM WED. EYES SHIFT SWD AS NWP MODELS CONTINUE TO DEVELOP A TROPICAL SYSTEM IN THE SRN GULF OF MEXICO NEAR THE YUCATAN. GFS SEEMS TOO AGGRESSIVE AND IS PLAGUED WITH CONVECTIVE FEEDBACK AS IT MOVES THE SYSTEM NNE TOWARD THE FL PANHANDLE LATE SAT. NAM IS MORE REASONABLE BUT PROBABLY TOO DEEP WITH PRESSURES. ONLY MINOR CHANGES WERE MADE TO THE CURRENT FORECAST ON FRIDAY WITH ONLY 20% FOR THE FL ZONES WITH ONLY SHOWER ACTIVITY AS INSTABILITY SEEMS A WEAK FOR THUNDERSTORMS. .LONG TERM...(SAT-WED). ON SAT GFS ENSEMBLE SHOWS UPPER LEVEL TROUGH OVER THE ERN GULF AND SFC LOW PRESSURE SYSTEM MOVING OUT OF THE YUCATAN STRAIT. BASED ON THIS SCENARIO N-S POP GRADIENT IS PLANNED WITH AROUND 30-40% S ZONES AND 20-30% N. GENERALLY USED A BLEND OF PREVIOUS FORECAST AND LATEST GFS RUN FOR THE POPS AND TEMPS. CONFIDENCE IS LOW SAT-SUN DUE TO MODEL DISAGREEMENT AND A NUMBER OF CHANGES WILL OCCUR WITH THE FORECAST. HOWEVER...BY EARLY MON MOST NWP GUIDANCE AGREES WITH THE LOW MOVING INTO THE WRN ATLC WITH POPS DECREASING TO AROUND 20-30% INTO MID WEEK. GENERAL BROAD TROUGHING DOMINATES THE ERN U.S. THROUGH WEDNESDAY. && .AVIATION...BRIEF PERIOD OF MVFR BETWEEN 08Z-12Z OTHERWISE VFR. EAST WINDS INCREASING TODAY WITH GUSTS TO 20 KNOTS AFTER 13Z. && .MARINE...NO HEADLINES. WINDS EAST 10 TO 15 KNOTS WITH 3 TO 5 FOOT SEAS. A CONTINUED ELEVATED RISK OF RIP CURRENTS DUE TO AN ONSHORE FLOW AND PERSISTING EASTERLY SWELLS. && .FIRE WEATHER...HAVE POSTED A RED FLAG FOR ALL OF THE INLAND COUNTIES OF NE FL DUE TO LOW RH AND HIGH DISPERSION. LOWEST RH`S TODAY (25-30%) WILL BE ACROSS THE SUWANNEE VALLEY REGION. ON THURSDAY...MIN RH`S ACROSS SUWANNEE VALLEY REGION FORECAST FALL TO 30-35% FOR 4 TO 5 HOURS SO HAVE ISSUED A FIRE WX WATCH. && .PRELIMINARY POINT TEMPS/POPS... AMG 90 61 89 63 / 0 10 20 10 SSI 82 70 82 70 / 0 20 20 0 JAX 85 63 86 64 / 0 10 20 10 SGJ 82 68 82 69 / 0 10 20 10 GNV 89 61 89 64 / 10 0 20 10 OCF 89 61 89 65 / 10 0 20 10 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...RED FLAG WARNING FROM 1 PM THIS AFTERNOON TO 7 PM EDT THIS EVENING FOR ALACHUA-BAKER-BRADFORD-CLAY-COLUMBIA-DUVAL- GILCHRIST-HAMILTON-MARION-NASSAU-PUTNAM-SUWANNEE-UNION. FIRE WEATHER WATCH FROM THURSDAY AFTERNOON THROUGH THURSDAY EVENING FOR COLUMBIA-GILCHRIST-HAMILTON-SUWANNEE. GA...NONE. AM...NONE. && $$ SHASHY/PETERSON fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 421 AM CDT WED MAY 30 2007 .DISCUSSION... SHORT TERM PRECIPITATION CHANCES AND AMOUNTS TODAY...AND THEN AGAIN THURSDAY NIGHT INTO FRIDAY HIGHLIGHT THE FORECAST CONCERNS. TODAY AND TONIGHT...CURRENT RADAR TRENDS INDICATE SQUALL LINE IS DYING OUT ACROSS NORTH CENTRAL KS WITH WEAK CELLULAR CONVECTION MOVING ACROSS THE WESTERN CWA AT FORECAST TIME. UPPER LEVEL TROUGH AND JET STREAM IN ITS AXIS REMAIN OVER EASTERN CO AT FORECAST TIME. NAM AND RUC INDICATE THE POSSIBILITY FOR SOME CONVECTION TO REDEVELOP BEHIND THE DYING SQUALL LINE THIS MORNING SO WILL LEAVE FLASH FLOOD WATCH IN EFFECT FOR NOW. DAY SHIFT CAN REEVALUATE THE LIKELIHOOD OF THIS REDEVELOPMENT BASED ON RADAR TRENDS AND MAKE A DECISION ON THE FLASH FLOOD WATCH. WITH PRECIPITABLE WATER VALUES NEAR 1.5 INCHES IT REMAINS POSSIBLE FOR CONVECTION TO DUMP RAINFALL RATES UP TO AN INCH PER HOUR...WHICH WOULD QUICKLY APPROACH OR EXCEED FLASH FLOOD GUIDANCE ACROSS MUCH OF NORTH CENTRAL KS. AS THE UPPER TROUGH MOVES INTO THE PLAINS THIS ENERGY WILL PUSH A COLD FRONT THROUGH THE FORECAST AREA THIS MORNING THROUGH THE EVENING HOURS SERVING AS A FOCUS FOR REDEVELOPING PRECIPITATION. WITH A STRATUS DECK AHEAD OF THIS FRONT SURFACE HEATING WILL BE LIMITED...MAKING SEVERE WEATHER LESS LIKELY ALONG THE FRONT. THE MAIN HAZARD ASSOCIATED WITH THE PRECIPITATION WILL BE IN THE FORM OF HEAVY RAIN WITH THE FORECAST SOUNDINGS INDICATING A TROPICAL SIGNAL TO THE AIRMASS. DUE TO HIGHER FLASH FLOOD GUIDANCE VALUES EAST OF THE CURRENT WATCH AREA...WIDESPREAD FLASH FLOODING DOES NOT SEEM LIKELY...HOWEVER LOCALLY HEAVY RAINFALL PRODUCING FLOODING CANNOT BE RULED OUT. THE MODELS ARE RELATIVELY CONSISTENT IN BRINGING THE FRONT SOUTHEAST THROUGH THE FORECAST AREA AFTER 06Z...AND THIS SHOULD AT LEAST TEMPORARILY END PRECIPITATION. TRIED TO MATCH POPS WHERE THE FRONT IS EXPECTED TO BE TODAY THROUGH THIS EVENING. HAVE CATEGORICAL POPS GOING ALONG THE FRONT. BROUGHT POPS TO AN END AFTER 12Z. THURSDAY THROUGH FRIDAY...JET STREAM LOOKS TO REMAIN OVER THE CENTRAL ROCKIES BRINGING GOOD CYCLOGENESIS TO THE TX/OK PANHANDLES AGAIN. THIS WILL BEGIN TO LIFT THE COLD FRONT FROM WEST TO EAST ACROSS THE FORECAST AREA. BECAUSE OF THIS THERE IS A CHANCE THAT BETWEEN ISENTROPIC LIFT AND ANY EMBEDDED SPEED MAX IN THE UPPER LEVEL FLOW THAT A THUNDERSTORM WILL DEVELOP OVER NORTH CENTRAL KS THURSDAY AFTERNOON. FOR THE REST OF THE CWA A RELATIVELY STABLE AIRMASS BEHIND THE FRONTAL BOUNDARY SHOULD ALLOW FOR AT LEAST PARTY CLOUDY SKIES AND THEREFORE SOME SUNSHINE THURSDAY AFTERNOON. AS THE FRONT LIFTS ACROSS THE ENTIRE FORECAST AREA THURSDAY NIGHT THE CHANCES FOR THUNDERSTORM DEVELOPMENT WILL INCREASE AS THE RETURN FLOW RIDING OVER THE BOUNDARY IS MORE LIKELY TO OVERCOME THE CAP AND ALLOW SCATTERED THUNDERSTORMS TO DEVELOP ACROSS THE FORECAST AREA. NAM AND GFS HAVE ALSO DISPLAYED SOME RUN TO RUN CONSISTENCY IN BRINGING A VORT MAX AROUND THE UPPER LOW FRIDAY MORNING...ENHANCING CONFIDENCE IN PRECIPITATION WITH THE RETREATING FRONT. WITH THE FRONT RETREATING THURSDAY NIGHT...AND THEN THE POTENTIAL VORT MAX MOVING THROUGH THE CENTRAL PLAINS FRIDAY MORNING INTO FRIDAY AFTERNOON HAVE GONE WITH MID TO UPPER CHANCE POPS (40-50 PERCENT) THURSDAY NIGHT THROUGH FRIDAY AFTERNOON ACROSS THE CWA. THE MODELS HAVE BEEN HINTING AT AN MCS DEVELOPING OVER CENTRAL KS THURSDAY NIGHT AND MOVING EAST ALONG THE RETREATING FRONT FRIDAY MORNING. WITH SOUTHERLY FLOW AT THE LOW LEVELS AND AN EXITING JET STREAK BRINGING FAVORABLE UPPER LEVEL SUPPORT OVER CENTRAL KS THURSDAY NIGHT THIS IS CERTAINLY A POSSIBILITY. ANY ORGANIZED CONVECTION WILL BRING ABOUT THE CHANCE FOR SOME SEVERE WEATHER AND MORE LIKELY HEAVY RAINFALL. AT THIS TIME THE DETAILS ARE DIFFICULT TO INTERPRET WITHOUT KNOWING FOR SURE HOW FAR SOUTHEAST THE FRONT WILL SLIDE. ONCE THIS IS DETERMINED IT SHOULD BE EASIER TO PLACE AN AREA MORE FAVORABLE FOR SEVERE WEATHER. THE PLACEMENT OF THE SECONDARY UPPER LEVEL JET STREAK/VORT MAX WILL ALSO LARGELY DETERMINE AREAS OF FAVORABLE UPPER LEVEL SUPPORT FOR ORGANIZED CONVECTION. FRIDAY NIGHT AND SATURDAY...UKMET AND GFS INDICATE THE UPPER LEVEL LOW TRACKING OFF TO THE NORTHEAST DURING THE PERIOD...SENDING THE FRONTAL BOUNDARY SOUTH ACROSS THE FORECAST AREA ONCE AGAIN. NOT REAL CONFIDENT IN THIS SOLUTION AT THIS TIME AS THERE IS NO OBVIOUS FEATURE UPSTREAM THAT FAVORS MOVING THE UPPER LEVEL LOW OFF TO THE EAST AS AN AMPLIFIED UPPER RIDGE SITS OVER THE ROCKIES. AT THIS TIME HAVE MATCHED UP WITH NEIGHBORS AND PLACED CHANCE POPS IN THIS PERIOD WITH THE POTENTIAL FOR CONVECTION ALONG THE FRONTAL BOUNDARY. CAVANAUGH && .AVIATION... WITH LACK OF CONVECTION MOVING INTO THE AREA ATTM...LOWER CIGS AROUND A THOUSAND FEET LOOK MORE LIKELY IN THE SHORTER TERM. BETTER CHANCES FOR CONVECTION WOULD APPEAR TO HOLD OFF UNTIL ARRIVAL OF BETTER UPPER AIR SUPPORT...I.E. LATER THIS AFTERNOON. SFC BOUNDARY THEN MOVES THROUGH DURING AFTN AND EVENING LIFTING CIGS AND BRINGING END TO TSTMS. BY EARLY THURSDAY, WE MAY BE PRONE TO SOME FOG WITH GOOD RESIDUAL MOISTURE AND VERY LIGHT LOW LEVEL WINDS. LATER FORECASTS WILL NEED TO KEEP THIS IN MIND. && .TOP WATCHES/WARNINGS/ADVISORIES...FLASH FLOOD WATCH THROUGH WEDNESDAY EARLY AFTERNOON FOR KSZ008>010-20>22-34>36. $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 420 AM EDT WED MAY 30 2007 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW HI AMPLITUDE PATTERN ACRS NAMERICA WITH TROF OVER THE NRN PLAINS UPSTREAM OF PERSISTENT RDG OVER THE E. SCT SHRA/TSRA THAT DVLPD OVER MAINLY THE W HALF OF THE CWA YDAY WITH ARRIVAL OF WEAK SHRTWV/H5 THERMAL TROF/ PWAT NEAR 1.5 INCHES HAS PRETTY MUCH WANED WITH LOSS OF DIURNAL HTG. SINCE WARM FNT E OF LO ARND INL IS TO THE N...JUST A FEW LINGERING SHRA ARE GOING OVER THE W...WITH JUST SOME LINGERING DEBRIS CLD FARTHER E. LOOKING UPSTREAM...00Z DVN SDNG DEPICTS A DRIER ATMOSPHERE (PWAT 1.01 INCH) THAT AT GRB (PWAT 1.33 INCH). DEEP MIXING TO H75 ON THIS SDNG WOULD CAUSE SFC DWPT TO DROP TO ARND 50 (VS ARND 60 OVER THE FA NOW). IN FACT...VERY LTL IF ANY CNVCTN DVLPD IN THIS AREA YDAY. OAX SDNG IS ALSO DRIER THAN MPX (PWAT 1.35 INCH VS 1.61 INCH AT MPX)...BUT NOT AS DRY AS DVN. OTRW...MORE VIGOROUS CNVCTN IS ONGOING OVER THE NCNTRL PLAINS IN ADVANCE OF MORE POTENT SHRTWV/100KT H3 JET MAX OVER THE CNTRL ROCKIES ROTATING ARND SRN FLANK OF NEARLY CLOSED LO OVER THE NRN PLAINS. MAIN FCST CONCERNS THIS PACKAGE ARE SHRA/TSRA CHCS OVER THE NEXT COUPLE OF DAYS AS UPR LO IN THE PLAINS DRIFTS SLOWLY TO THE E. FOR TDAY...GFS/NAM SHOW DEEP SSW FLOW AHEAD OF SLUGGISH CUTOFF LO IN THE NRN PLAINS. AS STRG SHRTWV ROTATING ARND SYS THIS MRNG DEEPENS THE UPR LO OVER SD TDAY...UPR RDG AXIS FCST TO SHARPEN OVER THE UPR LKS. SINCE H925-85 FLOW FCST TO BACK A BIT IN RESPONSE TO FALLING PRES TO THE W...EXPECT LLVL TRAJECTORIES TO COME FM THE DRIER SOURCE NR DVN. SINCE H925 FLOW IS ALSO FCST TO BE SLGTLY DIFFLUENT AND H5 TEMPS A FEW DEGREES HIER THAN YDAY (ARND -10C VS -12C)...SUSPECT SHRA/TSRA COVG TDAY WL BE LESS THAN YDAY. BEST CHC WOULD SEEM TO BE OVER THE W CLOSER TO SOMEWHAT MORE SUBSTANTIAL MSTR AND WHERE LK BREEZES MIGHT LOCALLY ENHANCE LLVL CNVGC. SINCE PRES GRADIENT/H925 SSW WIND IS FCST TO BE WEAKER TDAY THAN YDAY...LK BREEZE FORMATION LOOKS TO BE MORE LIKELY TDAY. HAVE OPTED TO TAKE OUT POPS OVER THE CNTRL AND RESTRICT MENTION OF 30-40 POPS TO W OF THE HURON MTNS/MQT TO IRON RIVER. MODIFIED GFS FCST SDNG FOR IWD AT 18Z FOR 80/57 YIELDS MLCAPE OF 400 J/KG (COMPARED WITH VALUES CLOSER TO 1000 J/KG YDAY). MIXING TO H75 ON GFS/NAM FCST SDNGS SUPPORTS HI TEMPS NR 83 AWAY FM LK MODERATION. TNGT...FA PROGGED TO REMAIN IN WARM SECTOR OF OCCLUDED LO IN THE NRN PLAINS. SINCE WARM FNT WL BE TO THE N...THINK PCPN CHCS WL BE MINIMAL AFT DIURNAL HTG WANES. ONLY FLY IN THE OINTMENT IS WEAK SHRTWV GFS LIFTS N WELL E OF CLOSED LO IN THE NRN PLAINS. THIS SHRTWV IS CURRENTLY IN THE MID MS RIVER VALLEY...BUT THERE HAVE BEEN ONLY A FEW -SHRA FM MID CLD DECK UNDER THIS SYS. SINCE UKMET/NAM ALSO SHOW THE MOISTENING DEPICTED BY THE GFS...HAVE OPTED TO RETAIN POPS TNGT OVER ALL BUT THE E...WHERE MOISTENING IS FCST TO BE LESS SUBSTANTIAL. SINCE INSTABILITY IS FCST TO BE MARGINAL AT BEST (FCST SSI GENERALLY AOA 0C)...DOWNGRADED POTENTIAL OF TS TO SCHC IN THE ABSENCE OF SGNFT DYNAMICS. OTRW...INCRSG MSTR/CLD COVER WL RESTRICT DIURNAL TEMP FALL...SO TENDED TOWARD THE HIER ETA MOS NUMBERS. LOOKS LIKE SHRA/TSRA CHCS WL INCRS ON THU ESPECIALLY OVER THE W HALF AS GFS/NAM/UKMET/CNDN ALL INDICATE A SHRTWV ROTATING NWD ON THE ERN FLANK OF PARENT CLOSED LO STILL STUCK IN THE NRN PLAINS MOVES INTO NW WI LATE IN THE DAY ALONG WITH ACCOMPANYING 80KT H3 JET MAX. GFS/ NAM FCST SDNGS SUG QUITE A BIT OF MID/HI CLD ASSOCIATED WITH SHRTWV THAT IMPACTS THE FA TNGT WL LINGER THRU THE DAY BEFORE ARRIVAL OF THIS SYS...SO DESTABILIZATION SHOULD NOT BE SGNFT. MODIFIED GFS FCST SDNG FOR 75/60 YIELDS MLCAPE APRCHG 600 J/KG. 0-6KM BULK SHEAR GENERALLY UNDER 25-30 KT AND HI WBZ > 12K FT WITH MARGINAL INSTABILITY SUG SVR THREAT MINIMAL. HOWEVER...OPTED TO BUMP POPS UP TO LIKELY OVER THE W HALF THU AFTN AFT LOWER CHC POPS EARLIER. GFS/UKMET/CNDN MODELS IN PRETTY GOOD AGREEMENT SHOWING DRY SLOTTING BEHIND LIFTING SHRTWV MOVING INTO THE FA SW-NE THU NGT. WL DIMINISH THEN END POPS IN THIS DIRECTION DURING THE NGT AS DRIER AIR ARRIVES. THEN WENT DRY ON FRI MRNG BEFORE INSTABILITY SHRA/TSRA CHCS INCRS AGAIN IN THE AFTN OVER THE W WITH SLOW APRCH OF VORTEX FM THE NRN PLAINS. CONSIDERING TREND TOWARD SLOWER EWD PROGRESSION OF THE CUTOFF...WL KEEP FRI DAY ALL DAY OVER THE E. COORDINATED WITH GRB/APX. KC && .MARINE (FOR 4 AM ISSUANCE OF LAKE SUPERIOR FCST)... A LOW PRES SYSTEM OVER NORTHERN MINNESOTA WILL GRADUALLY BACK WEST INTO NORTH DAKOTA TODAY AND REMAIN OVER THE CENTRAL DAKOTAS THROUGH FRIDAY. THE LOW WILL TRACK EAST FRIDAY NIGHT REACHING NORTHERN LAKE MICHIGAN ON SATURDAY. THE LOW WILL THEN TRACK INTO SOUTHERN QUEBEC ON SUNDAY. A WEAK COLD FRONT DEVELOPING OVER CENTRAL ONTARIO ON SATURDAY WILL SWEEP ACROSS LAKE SUPERIOR LATE ON SUNDAY. WINDS SHOULD GENERALLY BE BETWEEN 10 TO 15KT AT THE BUOY. OVER THE WEST HALF OF THE LAKE...AS IS TYPICAL IN SOUTHERLY WIND REGIMES OVER A VERY STABLE MARINE LAYER...WINDS WILL AGAIN REMAIN MAINLY EASTERLY NEAR THE MINNESOTA SHORELINE. FOR THE MOST PART... GENERALLY LIGHT WINDS WILL PREVAIL INTO THE UPCOMING WEEKEND AS WEAK PRESSURE GRADIENT WILL BE OVER THE AREA. FOG SHOULD BECOME AN ISSUE THROUGH AT LEAST THURSDAY EVENING ONCE SOME RAINFALL OCCURS OVER THE LAKE AND MOISTENS THE CHILLY MARINE LAYER UNDER SHARP INVERSION. && .AVIATION (FOR 06Z TAFS)... VFR CONDITIONS CAN BE EXPECTED OVERNIGHT. SOME PATCHY FOG OVER WESTERN LAKE SUPERIOR...DUE TO HIGH DEW POINTS AND COOL LAKE...MAY COME ON SHORE OVER THE KEWEENAW PENINSULA SO WILL INCLUDE A TEMPO FOR BR AROUND SUNRISE. THERE ARE A FEW SHOWERS ON RADAR MAINLY OVER LAKE SUPERIOR...HOWEVER...THESE ARE SO ISOLATED WILL NOT INCLUDE IN THE TAF AT THIS TIME. ANOTHER ROUND OF BROKEN CLOUD COVER AND SHOWERS AND THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC DISCUSSION...KC MARINE/AVIATION...DG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1151 PM CDT TUE MAY 29 2007 .AVIATION.../06Z TAF ISSUANCE/ TEMP/DP SPREADS ONLY A FEW DEGREES ATTM. FOG FORMING VICINITY OF AXN AND EXPECT MOST TAF SITES OVERNIGHT TO SEE MVFR CEILINGS AND VISIBILITIES. SOME SHOWERS WEST OF MSP THROUGH RWF MOVING NNW. THIS AREA ON NW WILL SEE INCREASING WAA IN THE 850-600MB LAYER INTO WEDNESDAY...SO THE THREAT FOR SHOWERS TO CONTINUE. CU RULE VERY NEGATIVE ON WEDNESDAY WITH BKN VFR CEILINGS FORECAST. INDICATED THUNDER VCNTY AT ALL SITES BEGINNING IN THE MID TO LATE AFTERNOON ALONG WITH A CHANCE OF SHOWERS AS A COLD FRONT PUSHES INTO WEST CENTRAL THROUGH SOUTH CENTRAL MN. && .DISCUSSION.../ISSUED AT 409 PM TUESDAY/ SHOWERS/THUNDERSTORMS CONTINUE TO INCREASE IN COVERAGE THIS AFTERNOON...AS MESOSCALE CONVECTIVE VORTEX LIFTS FROM EASTERN NEBRASKA/SOUTH DAKOTA INTO CENTRAL MINNESOTA. HIGHEST THREAT LOCALLY FOR SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING APPEARS TO BE ACROSS WEST CENTRAL MN...ROUGHLY FROM ALEXANDRIA TO MONTEVIDEO AND WESTWARD. THIS AREA IS IN CLOSE PROXIMITY TO THE SURFACE FRONT AND MCV...WHICH WAS BEGINNING TO SNEAK INTO WESTERN MINNESOTA AT 20Z. WILL NEED TO MONITOR THE EXTREME NORTHWESTERN CWA CLOSELY FOR NON-SUPERCELL TORNADOGENESIS...AS 20Z RUC/LAPS BOTH HIGHLIGHTED THAT AREA WITH A CORRELATED POCKET OF ENHANCED 0-3KM MLCAPE AND SURFACE VORTICITY. AFOREMENTIONED AREA ALSO HAS AN IMPRESSIVE AREA OF SURFACE THETA E CONVERGENCE...PER 20Z LAPS DATA. MID LEVEL LAPSE RATES ARE MARGINAL /AROUND 6.5 C/KM/ SO EXPECT ANY HAIL TO HAVE A HARD TIME REACHING SEVERE CRITERIA. THE SEVERE THREAT DIMINISHES WITH EASTWARD PROGRESSION ACROSS THE CWA...WHERE LOWER INSTABILITY IS PROGGED. OF NEXT CONCERN IS THE HEAVY RAINFALL POTENTIAL FOR TONIGHT...AS ACTIVITY BECOMES MORE WIDESPREAD ACROSS CENTRAL MN. COUPLED UPPER LEVEL JET STRUCTURE BEGINS TO SHIFT INTO THE NORTHERN PLAINS. THE ASSOCIATED DIFFERENTIAL DIVERGENCE COUPLET IS PROGGED TO SET UP OVER THE CENTRAL/EASTERN DAKOTAS...SO ANTICIPATE THE EXCESSIVE RAINFALL TO OCCUR WEST OF THE CWA. STILL EXPECT IT TO BE A GOOD SOAKER...WITH PRECIP AMOUNTS AROUND 1 INCH POSSIBLE ACROSS WESTERN MN /WHERE PWATS ARE AROUND 1.5 INCHES/. THE BLOCKING INFLUENCE OF THE STRONG EASTERN CONUS RIDGE WILL CAUSE THE UPPER LOW TO MAKE LITTLE IN THE WAY OF EASTWARD PROGRESSION OVER THE NEXT FEW DAYS. PREFER THE SLOWER ECMWF SOLUTION...WHICH YIELDS LINGERED PRECIPITATION CHANCES INTO SATURDAY. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ RAH/LS mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 636 AM CDT WED MAY 30 2007 .UPDATED DISCUSSION... UPPER LEVEL ENERGY ENTERING THE CENTRAL PLAINS HAS NOT KEPT MUCH PRECIPITATION GOING AS WAS ANTICIPATED WITH THE INITIAL FORECAST PACKAGE. THE MAIN COLD FRONT REMAINS WEST OF THE FORECAST AREA SO HAVE NOT DOWNPLAYED POPS TOO MUCH YET AS SHOWERS AND THUNDERSTORMS MAY DEVELOP ALONG THE FRONTAL BOUNDARY. THE CHANCES FOR THUNDERSTORMS THIS MORNING LOOK SMALL HOWEVER AND HAVE GONE WITH RAIN SHOWER WORDING WITH ISOLATED THUNDERSTORMS TO CONVEY THIS. WITH LITTLE CHANCE OF THUNDERSTORMS THIS MORNING THERE IS NOT MUCH OF A FLASH FLOOD THREAT LEFT ACROSS NORTH CENTRAL KANSAS...SO HAVE ALSO GONE AHEAD AND CANCELLED THE FLASH FLOOD WATCH THIS MORNING. IF PRECIPITATION DOES NOT DEVELOP ALONG THE FRONT AT ALL TODAY SIGNIFICANT CHANGES WILL HAVE TO BE MADE TO THE GOING FORECAST...HOWEVER RUC/NAM/GFS ALL INDICATE THAT PRECIPITATION WILL REDEVELOP ALONG THE FRONTAL BOUNDARY...SO HAVE NOT MADE SWEEPING CHANGES REDUCING POPS AT THIS TIME. CAVANAUGH && .PREV DISCUSSION... /ISSUED 421 AM CDT WED MAY 30 2007/ .DISCUSSION... SHORT TERM PRECIPITATION CHANCES AND AMOUNTS TODAY...AND THEN AGAIN THURSDAY NIGHT INTO FRIDAY HIGHLIGHT THE FORECAST CONCERNS. TODAY AND TONIGHT...CURRENT RADAR TRENDS INDICATE SQUALL LINE IS DYING OUT ACROSS NORTH CENTRAL KS WITH WEAK CELLULAR CONVECTION MOVING ACROSS THE WESTERN CWA AT FORECAST TIME. UPPER LEVEL TROUGH AND JET STREAM IN ITS AXIS REMAIN OVER EASTERN CO AT FORECAST TIME. NAM AND RUC INDICATE THE POSSIBILITY FOR SOME CONVECTION TO REDEVELOP BEHIND THE DYING SQUALL LINE THIS MORNING SO WILL LEAVE FLASH FLOOD WATCH IN EFFECT FOR NOW. DAY SHIFT CAN REEVALUATE THE LIKELIHOOD OF THIS REDEVELOPMENT BASED ON RADAR TRENDS AND MAKE A DECISION ON THE FLASH FLOOD WATCH. WITH PRECIPITABLE WATER VALUES NEAR 1.5 INCHES IT REMAINS POSSIBLE FOR CONVECTION TO DUMP RAINFALL RATES UP TO AN INCH PER HOUR...WHICH WOULD QUICKLY APPROACH OR EXCEED FLASH FLOOD GUIDANCE ACROSS MUCH OF NORTH CENTRAL KS. AS THE UPPER TROUGH MOVES INTO THE PLAINS THIS ENERGY WILL PUSH A COLD FRONT THROUGH THE FORECAST AREA THIS MORNING THROUGH THE EVENING HOURS SERVING AS A FOCUS FOR REDEVELOPING PRECIPITATION. WITH A STRATUS DECK AHEAD OF THIS FRONT SURFACE HEATING WILL BE LIMITED...MAKING SEVERE WEATHER LESS LIKELY ALONG THE FRONT. THE MAIN HAZARD ASSOCIATED WITH THE PRECIPITATION WILL BE IN THE FORM OF HEAVY RAIN WITH THE FORECAST SOUNDINGS INDICATING A TROPICAL SIGNAL TO THE AIRMASS. DUE TO HIGHER FLASH FLOOD GUIDANCE VALUES EAST OF THE CURRENT WATCH AREA...WIDESPREAD FLASH FLOODING DOES NOT SEEM LIKELY...HOWEVER LOCALLY HEAVY RAINFALL PRODUCING FLOODING CANNOT BE RULED OUT. THE MODELS ARE RELATIVELY CONSISTENT IN BRINGING THE FRONT SOUTHEAST THROUGH THE FORECAST AREA AFTER 06Z...AND THIS SHOULD AT LEAST TEMPORARILY END PRECIPITATION. TRIED TO MATCH POPS WHERE THE FRONT IS EXPECTED TO BE TODAY THROUGH THIS EVENING. HAVE CATEGORICAL POPS GOING ALONG THE FRONT. BROUGHT POPS TO AN END AFTER 12Z. THURSDAY THROUGH FRIDAY...JET STREAM LOOKS TO REMAIN OVER THE CENTRAL ROCKIES BRINGING GOOD CYCLOGENESIS TO THE TX/OK PANHANDLES AGAIN. THIS WILL BEGIN TO LIFT THE COLD FRONT FROM WEST TO EAST ACROSS THE FORECAST AREA. BECAUSE OF THIS THERE IS A CHANCE THAT BETWEEN ISENTROPIC LIFT AND ANY EMBEDDED SPEED MAX IN THE UPPER LEVEL FLOW THAT A THUNDERSTORM WILL DEVELOP OVER NORTH CENTRAL KS THURSDAY AFTERNOON. FOR THE REST OF THE CWA A RELATIVELY STABLE AIRMASS BEHIND THE FRONTAL BOUNDARY SHOULD ALLOW FOR AT LEAST PARTY CLOUDY SKIES AND THEREFORE SOME SUNSHINE THURSDAY AFTERNOON. AS THE FRONT LIFTS ACROSS THE ENTIRE FORECAST AREA THURSDAY NIGHT THE CHANCES FOR THUNDERSTORM DEVELOPMENT WILL INCREASE AS THE RETURN FLOW RIDING OVER THE BOUNDARY IS MORE LIKELY TO OVERCOME THE CAP AND ALLOW SCATTERED THUNDERSTORMS TO DEVELOP ACROSS THE FORECAST AREA. NAM AND GFS HAVE ALSO DISPLAYED SOME RUN TO RUN CONSISTENCY IN BRINGING A VORT MAX AROUND THE UPPER LOW FRIDAY MORNING...ENHANCING CONFIDENCE IN PRECIPITATION WITH THE RETREATING FRONT. WITH THE FRONT RETREATING THURSDAY NIGHT...AND THEN THE POTENTIAL VORT MAX MOVING THROUGH THE CENTRAL PLAINS FRIDAY MORNING INTO FRIDAY AFTERNOON HAVE GONE WITH MID TO UPPER CHANCE POPS (40-50 PERCENT) THURSDAY NIGHT THROUGH FRIDAY AFTERNOON ACROSS THE CWA. THE MODELS HAVE BEEN HINTING AT AN MCS DEVELOPING OVER CENTRAL KS THURSDAY NIGHT AND MOVING EAST ALONG THE RETREATING FRONT FRIDAY MORNING. WITH SOUTHERLY FLOW AT THE LOW LEVELS AND AN EXITING JET STREAK BRINGING FAVORABLE UPPER LEVEL SUPPORT OVER CENTRAL KS THURSDAY NIGHT THIS IS CERTAINLY A POSSIBILITY. ANY ORGANIZED CONVECTION WILL BRING ABOUT THE CHANCE FOR SOME SEVERE WEATHER AND MORE LIKELY HEAVY RAINFALL. AT THIS TIME THE DETAILS ARE DIFFICULT TO INTERPRET WITHOUT KNOWING FOR SURE HOW FAR SOUTHEAST THE FRONT WILL SLIDE. ONCE THIS IS DETERMINED IT SHOULD BE EASIER TO PLACE AN AREA MORE FAVORABLE FOR SEVERE WEATHER. THE PLACEMENT OF THE SECONDARY UPPER LEVEL JET STREAK/VORT MAX WILL ALSO LARGELY DETERMINE AREAS OF FAVORABLE UPPER LEVEL SUPPORT FOR ORGANIZED CONVECTION. FRIDAY NIGHT AND SATURDAY...UKMET AND GFS INDICATE THE UPPER LEVEL LOW TRACKING OFF TO THE NORTHEAST DURING THE PERIOD...SENDING THE FRONTAL BOUNDARY SOUTH ACROSS THE FORECAST AREA ONCE AGAIN. NOT REAL CONFIDENT IN THIS SOLUTION AT THIS TIME AS THERE IS NO OBVIOUS FEATURE UPSTREAM THAT FAVORS MOVING THE UPPER LEVEL LOW OFF TO THE EAST AS AN AMPLIFIED UPPER RIDGE SITS OVER THE ROCKIES. AT THIS TIME HAVE MATCHED UP WITH NEIGHBORS AND PLACED CHANCE POPS IN THIS PERIOD WITH THE POTENTIAL FOR CONVECTION ALONG THE FRONTAL BOUNDARY. CAVANAUGH && .AVIATION... WITH LACK OF CONVECTION MOVING INTO THE AREA ATTM...LOWER CIGS AROUND A THOUSAND FEET LOOK MORE LIKELY IN THE SHORTER TERM. BETTER CHANCES FOR CONVECTION WOULD APPEAR TO HOLD OFF UNTIL ARRIVAL OF BETTER UPPER AIR SUPPORT...I.E. LATER THIS AFTERNOON. SFC BOUNDARY THEN MOVES THROUGH DURING AFTN AND EVENING LIFTING CIGS AND BRINGING END TO TSTMS. BY EARLY THURSDAY, WE MAY BE PRONE TO SOME FOG WITH GOOD RESIDUAL MOISTURE AND VERY LIGHT LOW LEVEL WINDS. LATER FORECASTS WILL NEED TO KEEP THIS IN MIND. && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. $$ ks AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 1112 AM CDT WED MAY 30 2007 .UPDATE...MODELS ARE NOT HANDLING THE EVOLUTION OF DERECHO MOVING SOUTHEAST AROUND 35 MPH THROUGH NORTH TEXAS ATTM VERY WELL. 12Z GFS DOES NOT SHOW THE ORGANIZED COMPLEX NEAR DALLAS WHILE THE 12Z NAM DEVELOPS AN AREA OF CONVECTION NEAR COLLEGE STATION AROUND 18Z AND MOVES IT RAPIDLY SOUTH-SOUTHWEST THROUGH THE FORECAST AREA THIS AFTERNOON. THE RUC/NGM SEEMS TO HAVE THE BEST HANDLE ON THE CURRENT PRECIP AREAS WHICH IS A BIT UNSETTLING BECAUSE THESE MODELS TYPICALLY OVER OVERDONE WITH RESPECT TO QPF IN SOUTH TEXAS. THE CURRENT MOVEMENT WOULD BRING COMPLEX INTO SOUTHEAST TEXAS AROUND 21Z. MOST OF SOUTH TEXAS SHOULD BE UNDER THE INFLUENCE OF STRENGTHENING INVERSION. BUT VICTORIA CROSSROADS REGION MAY SEE A CHANCE FOR THUNDERSTORM DEVELOPMENT AS LOW LEVEL CONVERGENCE INCREASES WITH THE APPROACH OF OUTFLOW BOUNDARY FROM COMPLEX TO THE NORTH-NORTHEAST AND THE DEVELOPING SEABREEZE. WILL PUT IN A SLIGHT CHANCE OF STORMS IN THE FORECAST FOR THE VCT AREA THIS AFTERNOON. && .PREV DISCUSSION... /ISSUED 346 AM CDT WED MAY 30 2007/ SHORT TERM (TODAY THROUGH THURSDAY)...THE SMALL MCS AFFECTING WEBB COUNTY WL CONTINUE TO WEAKEN EARLY THIS MORNING. EXPECT RAINFALL TO END WITHIN THE NEXT 1-2 HOURS ACROSS WEBB COUNTY. OTHERWISE...A CONTINUED DRY FCST IS EXPECTED THROUGH THE FCST PD AS WIDESPREAD SUBSIDENCE CONTINUES WITH A DRY NWLY FLOW ALOFT. VERY MARGINAL MOISTURE AND SUFFICIENT WEAKENING OF THE CAP WL BE ENOUGH THAT A ROGUE CONVECTIVE CELL OR TWO WL STILL BE POSSIBLE ACROSS THE NORTHEAST COASTAL BEND THIS MORNING AND THU AFTN. WL CARRY 10% POPS TO COVER THIS. THE MAIN STORY WL BE THE WARM TEMPS. TEMPS WL PEAK TDA AND REMAIN BASICALLY THE SAME ON THU. OVERALL...THE GFS MOS TEMPS LOOK VERY GOOD AND WL BE FOLLOWED CLOSELY. MARINE (TODAY THROUGH THURSDAY)...A SUMMER-TIME FLAT GRADIENT WL PREVAIL THROUGH THURSDAY ACROSS THE COASTAL WATERS. THE USUAL SEABREEZE CYCLE WL ENHANCE THE ONSHORE FLOW IN THE AFTN AND EVE HOURS ACROSS THE BAYS AND NEARSHORE WATERS. STILL EXPECTING CONDITIONS TO REMAIN BELOW SCEC LVLS. SEAS WL AVG 3-5 FT. AVIATION...CONVECTIVE DEBRIS SPREADING ACROSS SOUTH TX THIS MORNING WL LIMIT THE DEVELOPMENT OF STRATUS AND FOG. EXPECT ONLY PATCHY MVFR CONDITIONS TO DEVELOP ACROSS INLAND PORTIONS OF THE COASTAL BEND THIS MORNING. VERY ISOLATED IFR CONDITIONS WL BE POSSIBLE ACROSS THE NORTHEAST COASTAL BEND (VCT TAF SITE) BETWEEN 10Z AND 13Z THIS MORNING. VFR CONDITIONS WL BE WIDESPREAD BETWEEN 15Z AND 18Z. SKIES WL CONTINUE TO THIN OUT DURING THE AFTN AND EVENING. MVFR CONDITIONS WL ONCE AGAIN DEVELOP AFTER MIDNIGHT TNT ACROSS TAF SITES SUCH AS ALI AND VCT. LONG TERM (THURSDAY NIGHT THROUGH SUNDAY)...MODELS IN AGREEMENT WITH UPPER LOW REMAINING ACROSS THE SE U.S. AND NRN GULF ON THU NITE THRU FRI. THE GFS SHOWS A SHORT WAVE EMBEDDED IN NLY FLOW ALOFT AND PRODUCING CONVECTION ACROSS SE TX AND BRUSHING THE EXTREME NE PORTIONS OF THE CWA ON FRI. LATEST SOLN INDICATES SUFFICIENT MOISTURE...INSTABILITY AND NO CAP FOR THE NE CWA...THEREFORE WILL CONTINUE WITH A SLIGHT CHC. FEEL UPPER DYNAMICS WILL BE TOO FAR REMOVED TO WARRANT GOING HIGHER THAN 20 POPS. THE UPPER LOW IS PROGD TO SHIFT NE AND WEAKEN THRU THE WEEKEND AS NRN STREAM LOW DIGS FARTHER S THUS MAINTAINING A N TO NW FLOW ALOFT. THE FLOW WILL BECOME INCREASINGLY SUBSIDENT WITH MUCH DRIER MID/UPPER LEVELS RESULTING IN A WARMING TREND THRU THE LONG TERM. A STRONG CAP DVLPS AND WITH THE LACK OF MOISTURE...PRECIP WILL BE NIL EXCEPT FOR THE POSSIBLE ROGUE SHRA DRIVEN BY THE SEA BREEZE ACROSS THE NE CWA WHERE THE CAP WILL BE WEAKEST. && .PRELIMINARY POINT TEMPS/POPS... CORPUS CHRISTI 89 72 89 70 88 / 10 10 10 0 10 VICTORIA 89 70 90 69 87 / 20 10 10 10 20 LAREDO 102 76 100 74 99 / 10 10 0 0 10 ALICE 93 71 93 70 90 / 10 10 10 0 10 ROCKPORT 87 74 87 73 86 / 10 10 10 0 10 COTULLA 95 72 94 72 95 / 10 10 0 10 10 KINGSVILLE 92 71 92 70 89 / 10 10 10 0 10 NAVY CORPUS 88 75 87 74 86 / 10 10 10 0 10 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ TMT/89...SHORT TERM JR/19...LONG TERM tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN ANGELO TX 1107 AM CDT WED MAY 30 2007 .UPDATE...HAVE UPDATED FORECAST TO REMOVE POPS TO THE SOUTHWEST FOR THE DAY AS THIS AREA IS IN THE MUCH STRONGER CAP AND DOUBT ANYTHING WILL DEVELOP SOUTHWEST OF A STERLING CITY TO SAN ANGELO TO SAN SABA LINE. ALSO PUSHED BACK TIMING OF THUNDERSTORM DEVELOPMENT TO THE NORTHWEST OF THAT LINE TIL AFTER 21Z AS WE HAVE TO WEAKEN THE CAP AND GET THE FRONT A LITTLE FURTHER TO THE SOUTH FOR BETTER CONVERGENCE. IF THUNDERSTORMS DO GET GOING THIS AFTERNOON...RUC FORECAST CAPES TO BE 4 TO 6 THOUSAND J/KG AND STORMS WILL LIKELY BE SEVERE. SO WENT AHEAD AND MENTIONED SEVERE FOR THIS AFTERNOON WHERE WE THINK STORMS WILL DEVELOP. ALSO COOLED TEMPERATURES ACROSS THE BIG COUNTRY...WHERE CLOUDS AND OUTFLOWS AND SOME FRONTAL EFFECTS WILL KEEP TEMPERATURES A LITTLE COOLER. FURTHER TO THE SOUTH WHERE THE STRONG CAP IS IN PLACE AND LESS EFFECTS FROM CLOUDS...OUTFLOWS AND FRONT...HAVE INCREASED TEMPERATURES A LITTLE. UPDATES TO FLY SOON. BRAZZELL && .PREV DISCUSSION... /ISSUED 611 AM CDT WED MAY 30 2007/ AVIATION... AREAS OF MVFR CIGS BKN015-025 ARE EXPECTED UNTIL 30/17Z ACROSS WEST CENTRAL TEXAS. MAINLY VFR CONDITIONS ARE EXPECTED AFTER 30/17Z. A THUNDERSTORM OUTFLOW BOUNDARY WILL MOVE INTO THE BIG COUNTRY THIS MORNING...AND THEN STALL OUT. SCATTERED TSTMS WILL DEVELOP ACROSS BIG COUNTRY NEAR THE BOUNDARY AFTER 30/20Z. ISOLD TSTMS WILL BE POSSIBLE ACROSS THE REMAINDER OF WEST CENTRAL TEXAS AFTER 30/20Z. 21 PREV DISCUSSION... /ISSUED 302 AM CDT WED MAY 30 2007/ SHORT TERM... COLD FRONT SOUTH OF AMARILLO AT 3 AM LIKELY TO MOVE SOUTH INTO THE BIG COUNTRY THIS MORNING AHEAD OF SCHEDULE...WITH A EXTRA PUSH FROM OUTFLOW FROM STRONG/SEVERE STORMS MOVING INTO WESTERN OKLAHOMA. WITH WRF SB CAPES OF 4000 J/KG BY MID AFTERNOON IN THE BIG COUNTRY...MAY SEE A FEW SEVERE THUNDERSTORMS. WILL MENTION SEVERE IN BIG COUNTRY ZONES TONIGHT. WRF MODEL HANGS UP FRONT ALONG I-20 TONIGHT...BEFORE LIFTING NORTH FRIDAY...BUT ACTUAL POSITION DEPENDS ON CONVECTION AND OUTFLOW BOUNDARIES THAT MAY DRIVE IT SOUTHWARD. A FEW THUNDERSTORMS ALSO POSSIBLE ON DRYLINE THAT WILL BE DEVELOPING IN CROCKETT COUNTY AND THE WESTERN CONCHO VALLEY IN THE AFTERNOON...THEN MOVE EAST IN THE EVENING. THIS A LESS LIKELY...BUT STILL POSSIBLE. CAP HAS BEEN HARD TO ERODE THE LAST COUPLE DAYS...EVEN THOUGH MODELS INDICATE LITTLE/NO CAP BY AFTERNOON. LONG TERM... UNSTABLE IN THE BIG COUNTRY AND EASTERN SECTIONS OF THE CWA ON FRIDAY. THURSDAY NIGHTS CONVECTION...THUNDERSTORM OUTFLOW BOUNDARIES WILL INFLUENCE RAIN CHANCES...BUT BEST CHANCES AROUND 30 PERCENT WILL AGAIN BE IN THE BIG COUNTRY. NORTHWEST UPPER LEVEL FLOW PATTERN DEVELOPS FRIDAY INTO THE WEEKEND. MAY SEE EVENING OROGRAPHIC CONVECTION DEVELOP IN THE MOUNTAINS AND PANHANDLE...THEN MOVE SOUTHEAST INTO LOW LEVEL FLOW. CHANCES OF IT REACHING THE BIG COUNTRY OR FURTHER SOUTH INTO THE CONCHO VALLEY ARE LOW EARLY FRIDAY AND SATURDAY MORNING...BUT POSSIBLE. RAIN CHANCES HOWEVER INCREASE EARLY SUNDAY AS ANOTHER COLD FRONT MOVES INTO REGION...WITH THE POTENTIAL FOR SEVERAL THUNDERSTORM COMPLEXES. HIGHER THAN NORMAL RAIN CHANCES CONTINUE INTO MONDAY. WARMER AND DRIER TUESDAY INTO WEDNESDAY AS AN UPPER RIDGE BUILDS INTO THE REGION. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 85 67 87 66 / 30 30 20 20 SAN ANGELO 92 68 89 67 / 10 20 20 20 JUNCTION 92 69 88 68 / 10 20 10 10 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 27/27 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 1040 AM CDT WED MAY 30 2007 .UPDATE LATEST WATER VAPOR SATELLITE IMAGERY INDICATING UPPER LEVEL LOW OVER THE NORTHERN PLAINS. WEAK SHORTWAVE TROUGH MOVED ACROSS FORECAST AREA THIS MORNING AND SCATTERED LIGHT RAIN SHOWERS ASSOCIATED WITH WAVE HAVE WEAKENED. NEXT STRONGER SHORTWAVE TROUGH OVER NORTHERN MISSOURI WILL LIFT NORTH INTO WESTERN WISCONSIN LATE THIS AFTERNOON. LATEST 12Z RUC AND NAM INDICATE DECENT 850MB MOISTURE TRANSPORT AND CONVERGENCE ASSOCIATED WITH SHORTWAVE TROUGH BY 21Z OVER FORECAST AREA. CURRENT MOSAIC RADAR INDICATES SCATTERED RAIN SHOWERS AND ISOLATED THUNDERSTORMS OVER SOUTHERN IOWA AND NORTHERN MISSOURI. WILL CONTINUE FORECAST TREND OF PRECIPITATION CHANCES OVER WESTERN AND SOUTHERN FORECAST AREA. HAVE ADJUSTED SKY GRIDS...AS DAYTIME HEATING HAS SCOURED OUT MID DECK OVER FORECAST AREA. WILL UPDATE FORECAST TO TAKE OUT MORNING WORDING AND SKY CONDITION TRENDS. && DTJ .PREV DISCUSSION... .SHORT TERM...TODAY THROUGH FRIDAY NIGHT FORECAST CONCERNS THIS PACKAGE...SHRA/TSRA CHANCES THROUGH THE PERIOD AS THE NORTHERN PLAINS UPPER LOW SLOWLY APPROACHES THE UPPER MIDWEST. SURFACE ANALYSIS AT 06Z SHOWED LOW PRESSURE FROM NORTHWEST MN TO EASTERN NEB AND THE TX PANHANDLE WITH HIGH PRESSURE OVER THE EASTERN CONUS. WIDE FETCH OF GULF MOISTURE BEING DRAWN NORTHWARD BETWEEN THE TWO. STRONG LOW LEVEL MOISTURE TRANSPORT/CONVERGENCE FUELING A LARGE CONVECTIVE COMPLEX OVER NEB/KS/OK EARLY THIS MORNING. WEAKER MOISTURE TRANSPORT...WARM ADVECTION/ISENTROPIC UPGLIDE PRODUCING A FEW -SHRA FROM SOUTHWEST MN TO MO. TEMPS AGAIN RATHER MILD ACROSS THE REGION EARLY THIS MORNING UNDER MOSTLY CLOUDY SKIES AND IN THE MOIST BOUNDARY LAYER AIRMASS. 30/00Z GFS/NAM LOOK TO HAVE A COUPLE OF MINOR INITIALIZATION ERRORS BUT OFFER QUITE SIMILAR SOLUTIONS FOR TODAY THRU FRI NIGHT. PER WV IMAGERY...NEITHER MODEL LOOKED STELLAR WITH THE SHORTWAVE ENERGY INITIALIZED OVER THE ROCKIES/WESTERN PLAINS. NAM INITIALIZED THE 300-250MB JET ON THE WEST SIDE OF THE NORTHERN PLAINS TROUGH 10- 15KTS TOO WEAK. DPROG/DT OF 500MB HGTS AT 30/00Z SHOWED THE 29/00Z NAM/GFS RUNS VERIFIED QUITE WELL ACROSS NOAM...WHILE THE 28/00Z RUNS WERE TOO WEAK/PROGRESSIVE WITH THE NORTHERN PLAINS TROUGH. THRU 36HRS MODELS HAVE CONVERGED ON A COMPROMISE OF THEIR PREVIOUS RUNS. GFS SHOWS THE BETTER RUN-TO-RUN CONSISTENCY WITH ITS 29/00Z RUN. FOR 36-60HRS MODELS CONTINUE TO CONVERGE ON A COMPROMISE OF THEIR EARLIER RUNS. FOR 60-84HRS THE TREND IS A BIT SLOWER...MORE CLOSED 500MB LOW THAN THE EARLIER GFS RUNS...BUT GFS OTHERWISE OFFERS REASONABLE RUN-TO-RUN CONTINUITY. CHECK OF OBS VS. MODEL DATA AT 06Z SHOWED BOTH NAM/GFS WITH GOOD DEPICTIONS OF THE SFC MASS FIELDS... WITH EDGE TO NAM ON SFC DEW POINTS ACROSS THE CENTRAL CONUS. PER WV IMAGERY...GFS LOOKED BETTER WITH ITS STRONGER SHORTWAVE OVER UT/ WESTERN CO...BUT APPEARED TO SUFFER CONVECTIVE FEEDBACK WITH A SHORTWAVE OVER WESTERN NEB. NAM LOOKED BETTER HERE INTO EASTERN MT/ SOUTHERN SASKAT. A NAM/GFS COMPROMISE LOOKED BEST WITH THE 00Z-06Z PRECIP ACROSS THE CONUS...AS WAS THE CASE FOR 18Z-00Z. WITH BETTER RUN-TO-RUN CONSISTENCY TO ITS 29/00Z RUN...AND APPARENT BETTER INITIALIZATION/HANDLING OF JET/SHORTWAVE ENERGY OVER THE CENTRAL ROCKIES...LEANED TOWARD GFS SOLUTION THIS CYCLE. HOWEVER...FAVORING NAM OR GFS OVER THE OTHER LOOKS TO HAVE LITTLE IMPACT ON THE SENSIBLE WEATHER THRU FRI NIGHT. SHORT TERM FORECAST CONFIDENCE AVERAGE THIS CYCLE. IN THE SHORT TERM...ONE BETTER CHANCE /LIKELY-HOOD/ OF SHRA/TSRA WITH THE DEVELOPING NORTHERN PLAINS UPPER LOW IMPACTS THE AREA CENTERED ON TONIGHT. SFC-850MB TROUGH/FRONT ROTATES AROUND THE DAKOTAS LOW AND INTO THE AREA TONIGHT WITH WEAK/MODERATE THETA-E CONVERGENCE AND SOME SFC-700MB FN CONVERGENCE. 925-850MB MOISTURE TRANSPORT INTO THE AREA INCREASES AHEAD OF THE TROUGH/FRONT AS WELL. WITH DEEP MOISTURE AND PW/S IN THE 1.5 INCH RANGE...EVEN THE WEAK/MDT FORCING SHOULD GENERATE NUMEROUS SHRA/TSRA AS THE TROUGH/FRONT MOVE THRU THE AREA. MODEL SOUNDINGS INDICATE STEEP SFC- 850MB LAPSE RATES AND MDT MID LEVEL LAPSE RATES WITH MINIMAL CIN AGAIN TODAY...THUS DIURNAL WARMING SHOULD AGAIN HELP INITIATE SOME CONVECTION THIS AFTERNOON. LOWERED POPS A BIT THIS MORNING...THEN RAISED THEM TOWARD CATEGORICAL MOST AREAS TONIGHT INTO THU MORNING. DRIER AIR/SUBSIDENCE...AT LEAST IN THE MID LEVELS...SPREAD ACROSS THE AREA FOR LATER THU/THU NIGHT INTO FRI MORNING. PREVIOUS FORECAST TRENDED RAIN CHANCE DOWN THU AFTERNOON AND THIS LOOKS GOOD. WITH DRIER AIR AND LACK OF FORCING/LIFT...LOWERED POPS TO SLIGHT CHANCE THU NIGHT. THIS BLENDS WELL WITH NEIGHBORING GRIDS FOR NOW...BUT IF TIMING AND STRENGTH OF DRYING/SUBSIDENCE CONTINUE TO HOLD LATER SHIFTS MAY BE ABLE TO CARRY A DRY FORECAST THU NIGHT. WITH LIGHT WINDS AND A MOIST BOUNDARY LAYER AIRMASS UNDER PARTLY CLOUDY SKIES THU NIGHT...FOG A CONCERN LATE THU NIGHT INTO FRI MORNING AND ADDED PATCHY WORDING TO GRIDS FOR NOW. SHRA/TSRA CHANCES INCREASE AGAIN CENTERED ON FRI NIGHT AS THE UPPER LEVEL LOW AND DEEPER LAYERED FORCING/LIFT AHEAD OF IT ARRIVE. ANOTHER SFC-850MB TROUGH/FRONT ALSO SWINGS ACROSS THE AREA FRI NIGHT...WITH INCREASING LOW LEVEL MOISTURE TRANSPORT/CONVERGENCE. WITH INCREASING MODEL CONSENSUS ON TIMING...RAISED FRI NIGHT POPS TO 50 PERCENT FOR NOW. IF GOOD MODEL TIMING/CONSENSUS CONTINUES FRI NIGHT POPS WILL PROBABLY NEED TO BE TRENDED TOWARD LIKELY/CATEGORICAL BY LATER SHIFTS. MAY NEED TO WATCH FRI NIGHT FOR HEAVY RAIN POTENTIAL AS WELL WITH THE DEEPER FORCING/LIFT. NUMERICAL GUIDANCE HIGHS/LOWS SIMILAR FOR TODAY/TONIGHT AND GENERALLY ACCEPTED. FAVORED BLEND OF GUIDANCE HIGHS FOR THU AND FOR LOWS THU NIGHT. GUIDANCE HIGHS FRI LOOK TO BE IN THE BALL PARK. TRENDED LOWS UP A BIT FRI NIGHT WITH INCREASING LOW LEVEL MOISTURE AND THICKENING CLOUDS. .LONG TERM...SATURDAY THROUGH TUESDAY MEDIUM RANGE MODELS CONTINUE TO LINGER THE UPPER LOW/TROUGH OVER THE REGION THRU THE WEEKEND...WITH ECMWF SLOWER THAN GFS. GFS ENSEMBLE MEAN AND UKMET TREND TOWARD A COMPROMISE OF THE ECMWF/OPERATION GFS. WITH THE UPPER LOW SPINNING OVER THE AREA...RAISED SHRA/ISOLD TSRA CHANCE A BIT ON SAT AND TRENDED HIGHS DOWN A DEGREE OR TWO. PREVIOUS GRID-SET IS DRY FOR SUN...BUT IF SLOWER ECMWF IS MORE CORRECT...SHRA CHANCE AND COOLER HIGHS WOULD BE NEEDED FOR SUN. MODELS CONTINUE TO SLIDE ANOTHER SHORTWAVE TOWARD THE AREA IN NORTHWEST FLOW ALOFT EARLY NEXT WEEK...WITH A SHRA/TSRA CHANCE CENTERED ON MON. THIS PRESENTLY WELL TRENDED IN THE SUN NIGHT THRU TUE FORECAST GRIDS. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ RRS wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 358 PM CDT WED MAY 30 2007 .DISCUSSION... WATER VAPOR AND PROFILER DATA SHOW RATHER SHARP MID LEVEL TROUGH MOVING ACROSS EASTERN KS THIS AFTERNOON. CONVECTION HAS DEVELOPED JUST AHEAD OF THIS TROUGH...ALONG/JUST BEHIND SURFACE WIND SHIFT LINE. REAL SURFACE FRONT TRAILS THIS AND CAN BE SEEN APPROACHING MHK WITH GUSTIER NWLY WINDS BEHIND IT. ANOTHER VORT MAX CAN BE SEEN IN RUC ANALYSIS OVER SW KS AT MID AFTERNOON AND WILL TRANSLATE EWD THIS EVENING. WOULD APPEAR THAT WITH SUBSIDENCE IN WAKE OF INITIAL UPPER TROUGH...AND DEEPER MOISTURE ALONG/AHEAD OF INITIAL SURFACE WIND SHIFT...SIGNIFICANT PRECIP CHANCES THIS EVENING WILL BE CONFINED TO FAR EASTERN KS...AND HAVE LOWERED POPS CONSIDERABLY FARTHER WEST. AS PRECIP CLEARS OUT OF EASTERN KS THIS EVENING...A WEAK RIDGE OF HIGH PRESSURE BUILDS IN WITH LIGHT WINDS AFTER MIDNIGHT. THAT COMBINED WITH AT LEAST PARTIAL CLEARING OF THE SKIES AND RESIDUAL LOW-LEVEL MOISTURE SUGGESTS FOG WILL BE A POSSIBILITY LATE TONIGHT. RIDGE MOVES EWD ON THURSDAY AND RETURN FLOW AND WARM AIR ADVECTION BY THURSDAY AFTERNOON INDICATES AT LEAST SMALL CHANCE OF PRECIP DURING THAT TIME. BOTH NAM AND NGM RATHER AGGRESSIVE IN BRINGING PRECIP INTO CENTRAL/EASTERN KS DURING THE AFTERNOON...WHILE GFS MUCH SLOWER. THIS IS REFLECTED IN POP CHANCES FROM GFS AND NAM MOS GUIDANCE WITH 40 TO 50% DIFFERENCES BETWEEN THE TWO. HAVE TENDED TO GO TOWARD LOWER POPS FROM GFS AS MAIN LIFT WOULD AT MOST AFFECT NC KS DURING THE AFTERNOON. GUIDANCE TEMPS FROM VARIOUS MODELS FOR TONIGHT AND THURSDAY ARE SIMILAR...AND CONSISTENT WITH GOING FORECAST...SO LITTLE CHANGE THERE. THURSDAY NIGHT THROUGH FRIDAY NIGHT...THE CLOSED UPPER LOW WILL SLOWLY DRIFT EASTWARD ACROSS THE NORTHERN PLAINS INTO THE MIDWEST. A SECONDARY 5H TROUGH WILL PIVOT SOUTHEAST ACROSS THE CENTRAL AND SOUTHERN PLAINS...LATE THURSDAY NIGHT AND FRIDAY...AROUND THE BASE OF THE CLOSED UPPER LOW. DEEP GULF MOISTURE OVER OK AND NORTH TX WILL SURGE NORTH ACROSS KS THURSDAY NIGHT. LIFT AHEAD OF THE APPROACHING 5H TROUGH AND A SURFACE COLD FRONT WILL CAUSE A LINE OR COMPLEX OF THUNDERSTORMS TO DEVELOP ACROSS WESTERN KS THURSDAY NIGHT. THIS LINE OR COMPLEX OF THUNDERSTORMS WILL MOVE EAST ACROSS THE CWA LATE THURSDAY NIGHT AND FRIDAY. THE GFS MODEL SHOWS THE FRONT STALLING OUT ACROSS THE CWA FRIDAY AFTERNOON INTO EARLY SATURDAY...WHILE THE NAM IS A BIT FASTER MOVING THE FRONT EAST OF THE CWA BY FRIDAY EVENING. ATTM I LEANED A BIT MORE TOWARDS THE GFS AND KEPT CHANCE POPS THROUGH FRIDAY NIGHT...WITH A SLIGHT CHANCE ON SATURDAY ACROSS THE EASTERN COUNTIES OF THE CWA. ANY HEAVY RAINFALL THREAT ACROSS THE CWA WILL BE DEPENDENT ON THE INTENSITY AND TRACK OF THE MCS OR COMPLEX THUNDERSTORMS THAT DEVELOP THURSDAY NIGHT AND THE EXACT TRACK OF ANY DEVELOPING MCS. HIGHS ON FRIDAY WILL BE DEPENDENT ON CLOUD COVER AND RAINFALL. ATTM I WENT MID TO UPPER 70S...THOUGH IF WE SEE MORE BREAKS IN THE CLOUD COVER DURING THE AFTERNOON HOURS HIGH TEMPS COULD BE UP NEAR 80 DEGREES. SATURDAY THROUGH TUESDAY NIGHT...THE 5H LOW WILL SLOWLY MOVE EAST ACROSS THE MIDWEST INTO THE MID ATLANTIC STATES. A 5H RIDGE WILL AMPLIFY ACROSS THE WESTERN CONUS. THIS SHOULD PROVIDE EAST KS WITH NORTHWEST FLOW ALOFT. EXPECT MAINLY DRY CONDITIONS WITH HIGH TEMPERATURES IN THE LOWER 80S. THOUGH ANY MINOR DISTURBANCE EMENDED IN THE NORTHWEST FLOW ALOFT COULD PROVIDE AN ISOLATED SHOWER OR THUNDERSTORM THREAT. WEDNESDAY...THE 5H RIDGE ACROSS THE WESTERN CONUS WILL MOVE EAST INTO THE HIGH PLAINS AS WINDS ALOFT BEGIN TO BACK FROM THE NORTHWEST TO THE WEST. HIGH TEMPERATURES MAY BE A BIT WARMER THAN THE FORECASTED MID 80S...POSSIBLY UPPER 80S TO NEAR 90. THOUGH IF WE BEGIN TO GET DEEPER MOISTURE RETURN ACROSS EASTERN KS MIXING DEPTHS COULD BE LOWER AND HIGHS WILL BE IN THE MID 80S. && .AVIATION... WHILE SHOWERS/TSTORMS STILL POSSIBLE THIS EVENING ACROSS FAR EASTERN KS...HAVE OPTED NOT TO GO MORE THAN VCTS IN TAF FOR FOE AND TOP FOR LATE THIS AFTERNOON/EARLY THIS EVENING. PREVIOUSLY MENTIONED FACTORS FAVORABLE FOR FOG HAVE LEAD ME TO A TEMPO 1 TO 2 SM VSBY FROM ABOUT 8 TO 12Z. WHILE CONSIDERABLE DRYING ALOFT IS FORECAST FROM GFS AND NAM TONIGHT...LOWEST LEVEL MIXING RATIOS INCREASE OFF THE SURFACE OR STAY STEADY OVER THE LOWEST 25 MB OR SO...SO DENSE FOG NOT OUT OF THE QUESTION. PRECIP CHANCES MENTIONED FOR THURSDAY AFTERNOON BEYOND 18Z TAF ISSUANCE PERIOD BUT BEST CHANCE WOULD BE NC KS ANYWAY. && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 249 PM MDT WED MAY 30 2007 .DISCUSSION... 17Z SFC ANALYSIS INDICATED COLD FRONT WAS WELL TO THE EST OF THE CWA WITH HIGH PRESSURE RIDGE BUILDING IN ACROSS EASTERN COLORADO. 17Z WATER VAPOR IMAGERY/RUC ANALYSIS INDICATES CUT OFF LOW TO THE NORTH OF THE CWA OVER NORTHERN NEBRASKA. NAM HAD A FEW INITIALIZATION PROBLEMS...AS IT WAS TO WEAK WITH JET STREAK AT KGJT AND WAS ALSO SEVERAL DEGREES TO WARM WITH H85 COLD AIR MASS AT KGGW. THE GFS ERRORS WERE OVERALL SMALLER. MODEL DIFFERENCES SMALL EARLY...BUT NAM AND GFS DIVERGE WITH HANDLING OF H5 LOW...WITH SREF SUPPORTING THE GFS AND INITIALIZATION PROBLEMS WILL LEAN IN THIS DIRECTION. TONIGHT...PRIMARY CONCERN WILL BE ANY PRECIP CHANCES AS AFTERNOON HEATING WILL RESULT IN A WEAKLY UNSTABLE AIRMASS WITH LITTLE INHIBITION. WILL KEEP GOING LOW POP FORECAST GOING THROUGH THE EVENING. ALTHOUGH PRECIPITATION WILL BE STRONGLY DIURNALLY DRIVEN...SOME INDICATION OF ELEVATED INSTABILITY OVERNIGHT IN PRESENCE OF WEAK H7 WAA. AM GOING TO KEEP SOME LOW POPS IN THE NORTH OVERNIGHT...IN CASE EARLY EVENING CONVECTION SATURATES THE MID LEVELS ENOUGH TO REALIZE ELEVATED INSTABILITY LATER. THURSDAY-THURSDAY NIGHT...CWA WILL REMAIN ON THE PERIPHERY OF H5 LOW THROUGH THE DAY. SFC TROUGH WILL DEVELOP OVER THE AREA...PROVIDING A WEAK AREA OF CONVERGENCE AND POTENTIAL THUNDERSTORM DEVELOPMENT. MAIN CONCERN WILL BE MOISTURE RETURN AFTER TODAYS FROPA...BUT WITH TD`S STILL IN THE 50S...AND RELATIVELY COLD AIR ALOFT DO THINK THAT MOISTURE RETURN WILL NOT BE THAT BIG OF AN ISSUE. H5 WINDS INCREASE TO NEAR 60KTS DURING THE AFTERNOON...AND GFS BUFR SOUNDINGS SHOWING VERY LONG...FAIRLY STRAIGHT HODOGRAPHS. NEXT SHORTWAVE TROUGH WILL BEGIN TO SLIDE ACROSS THE CWA AFTER 00Z AS LOW LVL JET BEGINS TO INTENSIFY. GFS HAS STRONGEST FORCING ON NOSE OF LLJ ACROSS NORTHERN CWA...WITH FAIRLY IMPRESSIVE (11-13 G/KG) MIXING RATIOS FEEDING INTO THIS AREA. SREF NOT QUITE AS AGGRESSIVE AS OPER GFS...BUT STILL SHOWS H85 FRONTAL BOUNDARY ACROSS NORTHERN CWA AS LATE AS 06Z. INITIAL THOUGHTS WERE TSRA WOULD FORM ALONG THE TROUGH AND RAPIDLY MOVE EAST...BUT NEXT SHORTWAVE TROUGH...AND POTENTIAL NOSE OF LLJ BEING ACROSS THE NORTHERN CWA THINK THAT PRECIP POTENTIAL MAY LAST THROUGH THE NIGHT AND UPPED POPS TO HIGH CHANCE CATEGORY. IF LLJ/FRONT INTERACTION DOES BEGIN ACROSS THE NORTH...MAY HAVE HYDRO ISSUES ONCE AGAIN. HOWEVER...WITH STRONG MID LEVEL FLOW STORMS WILL LIKELY BE MOVING FASTER THAN THE LAST FEW DAYS...THIS COMBINED WITH OVERALL UNCERTAINTY WILL KEEP ME FROM ISSUING ANY FLOOD WATCHES...BUT WILL HAVE TO KEEP AN EYE ON THINGS. FRIDAY-FRIDAY NIGHT...COLD FRONT WILL BE WORKING ITS WAY OUT OF THE AREA BY FRIDAY MORNING...PUSHING MOST OF THE INSTABILITY TO THE SOUTH ALONG WITH IT. H5 TROUGH WILL STILL BE LIFTING ACROSS THE AREA IN THE MORNING...SO PRECIP MAY LINGER IN THE MORNING PERIODS BUT SHOULD QUICKLY COME TO AN END AFTER FROPA. EXTENDED...GFS/ECMWF IN REASONABLE AGREEMENT WITH H5 FIELDS THROUGH MUCH OF THE PERIOD...ALTHOUGH MODELS DO BEGIN TO DIVERGE LATE. GFS ENSEMBLE MEANS TEND TO SUPPORT ECMWF IN THE LATER PERIODS AND WILL LEAN IN THIS DIRECTION. MAIN CONCERN FOR PERIOD WILL BE TEMPERATURES WITH A FEW SMALL PRECIP CHANCES THROUGHOUT THE PERIOD. THINK WARM UP MAY BE A BIT SLOWER THAN PREVIOUSLY THOUGHT AS MODEL CONSENSUS SUPPORTS IDEA OF MORE AMPLIFIED FLOW SETTING UP IN THE AREA DURING THE PERIOD...RESULTING IN A SLOWER EASTWARD PROGRESSION OF H5 RIDGE AND RESULTING WARMING TEMPS. WHILE MODELS AND ENSEMBLES SUPPORT THE FLATTENING RIDGE BY TUESDAY/WEDNESDAY WHILE THE LATEST GFS KEEPS FLOW VERY MUCH AMPLIFIED. AM NOT GOING TO FOLLOW LATEST GFS SOLUTION...BUT WILL WARM UP TEMPS SEVERAL DEGREES FOR TUE-WED. .AVIATION...STRATOCUMULUS AT KGLD/KMCK BASED AROUND 3500 FEET WILL DISSPIATE AFTER SUNSET. CONVECTION HAS DEVELOPED IN NORTHEAST COLORADO. THERE IS A CHANCE THAT TSRA COULD CONTINUE PAST SUNSET THERE...BUT WILL NOT INDICATE ANY IN THE TERMINAL FORECASTS. OTHERWISE...VFR CONDITIONS WILL CONTINUE UNTIL THURSDAY AFTERNOON WHEN A BETTER CHANCE FOR CONVECTION WILL DEVELOP. .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE && $$ JRM ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DODGE CITY KS 246 PM CDT WED MAY 30 2007 .DISCUSSION... DAYS 1-2... MAIN CONCERN THIS EVENING WILL BE CHC OF EVENING CONVECTION UNDER A -18 TO -20C 5H COLD POOL WHICH WILL BE CROSSING THE CWA EARLY THIS EVENING. BASED ON SAT AND RADAR TRENDS APPEARS THE THE BETTER DEVELOPMENT OF CU IS ALONG AND AHEAD OF THE NAM/RUC 5H VORT LOBE WHICH WAS MOVING EAST ACROSS THE CWA AT THIS TIME. WILL CONTINUE TO MONITOR THIS BUT AT THIS TIME PLAN IS TO INSERT ONLY SMALL 10-15 POPS ALONG AND AHEAD OF THIS VORT LOBE AS IT CROSSES THE CWA. AFTER THIS ALL MODELS REMAIN IN GOOD AGREEMENT WITH OUR UPPER LOW OVER THE NRN PLAINS MOVING VERY LITTLE THROUGH THE END OF THE WORK WEEK. SEVERAL IMPULSES AND JET STREAKS PROGGED TO MOVE AROUND THIS SYSTEM WITH ONE OF WHICH PLACES SOUTHWEST KANSAS IN THE RIGHT ENTRANCE REGION OF THE UPPER JET BY THURSDAY NIGHT. ALSO SEEING NICE 85-7H WA AND MOISTURE ADV ACROSS SW LATE IN THE DAY WITH PROB OF CAPES GREATER THAN 1000J/KG PROGGED BY SREF IS GREATER THAN 70 PERCENT BY 00Z FRIDAY. AS A RESULT LOOKS LIKE THE PREVIOUS FORECAST IS STILL LOOKING REASONABLE WITH PCP SPREADING INTO THE AREA LATE THURSDAY WITH THE BETTER OPPORTUNITY OF TSRA THURSDAY NIGHT. ON FRIDAY WILL STILL HAVE A FRONT IN OR NEAR OUR CWA AS YET ANOTHER S/W TROF MOVES SOUTHEAST ACROSS THE WESTERN HIGH PLAINS TOWARDS WESTERN KANSAS. LOCATION OF THE SFC FRONT REMAINS SOMEWHAT UNCERTAIN WITH MODELS DISAGREEING ON TIMING AND LOCATION AT 00Z SAT. AS A RESULT WILL FOLLOW GENERAL CONSENSUS AT SMALL POPS ACROSS THE ENTIRE AREA EARL FRIDAY WITH HIGH CHC POPS BY FRIDAY NIGHT. DAYS 3-7... GLOBAL MODELS ARE IN REASONABLE AGREEMENT WITH THE EVOLUTION OF QUASI-STATIONARY UPPER LOW CURRENTLY SITUATED OVER THE NORTHERN GREAT PLAINS. AS LONG AS THIS UPPER FEATURE REMAINS OVER THE MIDWEST STATES...THEN THIS WILL KEEP WESTERN KANSAS IN A NORTHWEST FLOW PATTERN WITH EFFECTIVE SURFACE BOUNDARY JUST SOUTH OF SOUTHWEST KANSAS THROUGH AT LEAST SUNDAY AND PROBABLY INTO MONDAY AS WELL. THE MAIN CHALLENGE GOING INTO EARLY NEXT WILL BE THE TRANSITION FROM NORTHWEST FLOW PATTERN FROM THE WEAKENING/DEPARTING MIDWEST LOW/TROUGH...TO A MORE WESTERLY FLOW AS VERY STRONG PACIFIC JET BEGINS TO APPROACH THE PACIFIC NORTHWEST REGION. IT WILL BE VERY INTERESTING TO SEE HOW THIS PATTERN NEXT WEEK WILL EVOLVE. THE ECMWF AND GFS SHOW AN INCREASINGLY BLOCKY LOOKING PATTERN NOW EARLY NEXT WEEK...AN OMEGA BLOCK TYPE PATTERN IN FACT...WITH RIDGING CENTERED OVER THE ENTIRE LENGTH OF THE ROCKIES WELL INTO CANADA. THE DAY 6-7 ECMWF MODEL FROM THE 30/00Z RUN SUGGESTS THAT THIS BLOCKING WILL NOT BE THAT STRONG AND SUFFICIENT FLOW WILL LIKELY CUT THROUGH THE OMEGA BLOCK SUPPORTING FAVORABLE LOWER TROPOSPHERIC SETTING FOR ORGANIZED SEVERE THUNDERSTORM EPISODES (ROUGHLY JUNE 5-8 TIME FRAME). && .AVIATION... NO MAJOR CHALLENGES FOR AVIATION CONCERNS THE NEXT 24 HOURS AS VFR CONDITIONS SHOULD PREVAIL. EXPECT WINDS TO CONTINUE TO SLOWLY VEER FROM NORTH-NORTHWEST TO NORTHEAST THROUGH THE REST OF THE AFTERNOON/EARLY EVENING AND WEAKEN TO 7 KNOTS OR LESS AS WE HEAD DEEPER INTO THE EVENING. BY 12Z OR SO THURSDAY MORNING...WINDS WILL BEGIN TO INCREASE OUT OF THE SOUTH AROUND 12-15 KNOTS AS WEAK SURFACE HIGH SHIFTS EAST INTO MISSOURI. && .PRELIMINARY POINT TEMPS/POPS... DDC 53 77 58 76 / 0 40 40 30 GCK 53 77 57 75 / 10 40 40 20 EHA 54 78 59 78 / 0 30 30 20 LBL 54 79 59 79 / 0 30 30 20 HYS 51 76 58 75 / 20 40 50 30 P28 54 79 61 79 / 20 40 50 30 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ FN18/25/25 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 435 PM EDT WED MAY 30 2007 .SHORT TERM (TONIGHT/THU)... MAIN FCST ISSUE CONTINUES TO BE SHRA/TSRA POTENTIAL. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A BROAD MIDLEVEL LOW OVER THE WRN DAKOTAS/ERN MT. A NUMBER OF SHORTWAVES ARE ROTATING AROUND THE LOW THRU THE CNTRL ROCKIES/WRN PLAINS. TO THE E...THE WRN GREAT LAKES REGION IS WITHIN DEEP LAYERED SW FLOW BTWN THE MIDLEVEL LOW AND THE DOWNSTREAM RIDGE COVERING THE SE STATES TO THE GREAT LAKES. WITHIN THE FLOW...THERE ARE NO DISCERNIBLE SHORTWAVES UPSTREAM THAT WILL AFFECT UPPER MI THRU AT LEAST THIS EVENING. SHRA/TSRA HAVE ONCE AGAIN DEVELOPED DURING THE HEAT OF THE DAY OVER THE W THIRD OF THE FCST AREA...SIMILAR TO WHAT OCCURRED YESTERDAY. RECENT ANALYSIS SHOWS MLCAPE NEAR 1000J/KG IN THAT AREA. SINCE THERE ARE NO APPARENT SHORTWAVES MOVING TOWARD THE AREA THIS EVENING...EXPECT ONGOING SCT SHRA/TSRA TO DISSIPATE GRADUALLY WITH LOSS OF DAYTIME HEATING/DIMINISHING INSTABILITY. SO...WILL AGAIN TRANSITION TO A DRY FCST FOR THE OVERNIGHT HRS...SIMILAR TO LAST NIGHT. ONLY EXCEPTION IS OVER THE FAR W. STRONGER SHORTWAVE ROTATING THRU NEBRASKA WILL BE CLOSE ENOUGH LATE TONIGHT TO WARRANT CHC POPS AGAIN OVER THE FAR W LATE IN THE NIGHT. CONSIDERED ADDING A MENTION OF FOG...BUT WITH 15-20KT WINDS JUST ABOVE THE SFC...SEEMS UNLIKELY FOG WILL BECOME DENSE ENOUGH TO SIGNIFICANTLY REDUCE VSBY. SHOULD BE MORE OF AN AVIATION ISSUE WITH 3-5SM TYPE VSBY. ONLY EXCEPTION IS ON THE KEWEENAW WHERE SFC WIND FIELD MAY HAVE A LIGHT UPSLOPE ESE COMPONENT AND NEAR LAKE MICHIGAN WHERE LIGHT ONSHORE WIND WILL ALSO BE OCCURRING. WILL MENTION PATCHY FOG IN THOSE AREAS. SHOULD BE ANOTHER MILD NIGHT WITH MINS IN MOST LOCATIONS NOT LWR THAN THE LWR 60S. STRONGER SHORTWAVE WILL PINWHEEL TOWARD UPPER MI THU EVEN THOUGH MIDLEVEL LOW WILL REMAIN OVER THE CNTRL/WRN DAKOTAS. ALONG WITH THE SHORTWAVE...AN ASSOCIATED SFC TROF WILL ALSO PUSH W INTO UPPER MI. SHORTWAVE/SFC TROF SHOULD PROVIDE A NICE FOCUSING FOR GREATER COVERAGE OF SHRA/TSRA. GFS/NAM TIMING IS SIMILAR...SUGGESTING PCPN THREAT WILL REACH THE W IN THE MORNING AND THE CNTRL BY AFTN. ONCE AGAIN...STABILIZATION OFF LAKE MICHIGAN IN SRLY FLOW MAY LIMIT SHRA POTENTIAL E OF MARQUETTE/ESCANABA LINE. ALSO...SINCE SHORTWAVE WILL BE LIFTING MORE N THAN E...FORCING FARTHER E WILL BE WEAKER. INITIAL THOUGHT WAS TO LEAVE THE ERN FCST AREA DRY THRU THU AFTN...BUT WILL JUST KEEP LWR CHC POPS THERE FOR NOW. MODIFIED GFS FCST SOUNDING FOR A SFC T/TD OF 77/60F YIELDS SBCAPE AROUND 700J/KG. HOWEVER...IT IS A BIT UNCERTAIN HOW WARM IT WILL GET BEFORE SHRA/TSRA ARRIVE SINCE THERE SHOULD BE A FAIR AMOUNT OF CLOUD COVER AHEAD OF PCPN. BEST DEEP LAYER SHEAR UPWARDS OF 40KT (SUFFICIENT FOR ORGANIZED SVR CONVECTION) LAGS JUST BEHIND SFC TROF AND EXPECTED AREA OF SHRA/TSRA. NONETHELESS...IT IS CLOSE AND SUGGESTS A POTENTIAL THAT A FEW STORMS MAY APPROACH SVR CRITERIA IF ENOUGH INSTABILITY DEVELOPS. LATER FCSTS WILL NEED TO REEXAMINE POTENTIAL OF SVR STORMS. .LONG TERM (THURSDAY NIGHT THROUGH WEDNESDAY)... MODELS CONTINUE TO BE IN GOOD AGREEMENT BEHIND AND EXITING SHORTWAVE...WITH DRY SLOT EXPECTED TO SLIDE INTO THE WESTERN UPPER PENINSULA THURSDAY EVENING...MAKING IT INTO THE EASTERN ZONES SHORTLY AFTER 06Z. WITH A MORE PROLONGED PERIOD OF FEW CLOUDS...HAVE KEPT THE LOWER TEMPERATURES ACROSS THE WESTERN HALF OF THE AREA. OUR MEANDERING SURFACE LOW TO THE WEST WILL CONTINUE ON THE SAME COURSE UNTIL SATURDAY. AS A RESULT...WE WILL CONTINUE TO SEE MAINLY AFTERNOON AND EARLY EVENING SHOWERS AND THUNDERSTORMS. SOME DISCREPANCIES SHOW UP IN THE PRECIPITATION FIELDS COME SATURDAY MORNING AND AFTERNOON...ESPECIALLY WHEN COMPARING THE GFS AND NAM. THE NAM HAS CONTINUED TO BE QUICKER THAN A MAJORITY OF THE OTHER MODELS AND AS A RESULT...HAVE THROWN IT OUT AFTER 00Z SATURDAY. HOWEVER...PRIOR TO 00Z SATURDAY THERE ARE FEW LARGE SCALE DIFFERENCES AND HAVE INCORPORATED SOME OF THE NAM SOLUTION INTO THE FORECAST. WHILE THE GFS AND ECMWF ARE ON A SIMILAR PAGE...EJECTING OUT THE 500MB LOW OVER LAKE SUPERIOR 12Z SUNDAY...THE CANADIAN IS ALSO ON ITS OWN. IT KEEPS THE STRONG CUTOFF LOW OVER THE EASTERN DAKOTAS AND WEST CENTRAL MINNESOTA AT THIS TIME...NOT REALLY MOVING IT OUT UNTIL LATE MONDAY. && .MARINE (FOR 4 PM ISSUANCE OF LAKE SUPERIOR FCST)... LIGHT WINDS (UNDER 20KT) WILL PREVAIL FOR THE ENTIRE FCST PERIOD UNDER A GENERALLY WEAK PRES GRADIENT. FOG WHICH WILL BE DENSE AT TIMES WILL PERSIST THROUGH AT LEAST THU AND POTENTIALLY INTO THE WEEKEND AS THERE IS LITTLE OPPORTUNITY FOR ADVECTION OF DRIER AIR INTO THE AREA. && .AVIATION (FOR 18Z TAFS)... SCT SHRA AND A FEW TSRA WILL CONTINUE TO DEVELOP OVER ROUGHLY THE W HALF OF UPPER MI THIS AFTN. OPTED TO INCLUDE A MENTION OF VCNTY THUNDER AT KCMX THIS AFTN AS DEVELOPING LAKE BREEZE SHOULD PROVIDE A FOCUS FOR BETTER CONVECTIVE DEVELOPMENT AROUND THE KEWEENAW PENINSULA. LEFT OUT EXPLICIT MENTION OF THUNDER AT KSAW FOR NOW. EXPECT CONVECTION TO DISSIPATE DURING THE EVENING WITH LOSS OF DAYTIME HEATING. FOG MAY THEN BECOME AN ISSUE LATE EVENING/OVERNIGHT...ESPECIALLY IF RAINFALL OCCURS AT EITHER TAF SITE DURING TEH AFTN/EARLY EVENING. BROUGHT VSBY DOWN MORE AT KCMX (1SM) THAN AT KSAW AS IT APPEARS THERE WILL BE A LIGHT UPSLOPE ESE FLOW THERE OVERNIGHT. DISTURBANCE APPROACHING THU SHOULD BRING A BETTER POTENTIAL FOR SHRA/TSRA TO BOTH TAF SITES. TIMING IS A BIT UNCERTAIN...SO HAVE ONLY INCLUDED A PROB GROUP TOWARD THE END OF TAF PERIOD AT KCMX. PCPN SHOULD ARRIVE JUST BEYOND 18Z AT KSAW. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM/AVIATION/MARINE...ROLFSON LONG TERM...KF mi AREA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE MARQUETTE MI 135 PM EDT WED MAY 30 2007 .AVIATION (FOR 18Z TAFS)... SCT SHRA AND A FEW TSRA WILL CONTINUE TO DEVELOP OVER ROUGHLY THE W HALF OF UPPER MI THIS AFTN. OPTED TO INCLUDE A MENTION OF VCNTY THUNDER AT KCMX THIS AFTN AS DEVELOPING LAKE BREEZE SHOULD PROVIDE A FOCUS FOR BETTER CONVECTIVE DEVELOPMENT AROUND THE KEWEENAW PENINSULA. LEFT OUT EXPLICIT MENTION OF THUNDER AT KSAW FOR NOW. EXPECT CONVECTION TO DISSIPATE DURING THE EVENING WITH LOSS OF DAYTIME HEATING. FOG MAY THEN BECOME AN ISSUE LATE EVENING/OVERNIGHT...ESPECIALLY IF RAINFALL OCCURS AT EITHER TAF SITE DURING TEH AFTN/EARLY EVENING. BROUGHT VSBY DOWN MORE AT KCMX (1SM) THAN AT KSAW AS IT APPEARS THERE WILL BE A LIGHT UPSLOPE ESE FLOW THERE OVERNIGHT. DISTURBANCE APPROACHING THU SHOULD BRING A BETTER POTENTIAL FOR SHRA/TSRA TO BOTH TAF SITES. TIMING IS A BIT UNCERTAIN...SO HAVE ONLY INCLUDED A PROB GROUP TOWARD THE END OF TAF PERIOD AT KCMX. PCPN SHOULD ARRIVE JUST BEYOND 18Z AT KSAW. && .UPDATE (ISSUED AT 1100 AM EDT)... MAIN FCST ISSUE THIS AFTN IS SHRA/TSRA POTENTIAL. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A MIDLEVEL LOW CLOSING OFF OVER THE WRN DAKOTAS/ERN MT. THE WRN GREAT LAKES REGION IS WITHIN DEEP LAYERED SW FLOW BTWN THE MIDLEVEL LOW AND THE DOWNSTREAM RIDGE COVERING THE SE STATES TO THE GREAT LAKES. THERE ARE NO DISCERNIBLE SHORTWAVES UPSTREAM THAT WILL AFFECT UPPER MI THIS AFTN. IT HAS BEEN A DRY MORNING ACROSS THE FCST AREA...AND THERE ARE ONLY SOME MID/HIGH CLOUDS PASSING ACROSS UPPER MI. SINCE THERE ARE NO APPARENT SHORTWAVES MOVING TOWARD THE AREA THIS AFTN...WILL NEED TO RELY ON AFTN INSTABILITY FOR SHRA/TSRA DEVELOPMENT. MODIFIED 12Z KGRB SOUNDING FOR AN EXPECTED SFC T/TD OF 85/57F THIS AFTN CAN GET PARCELS JUST PAST A CAP AROUND 600MB...AND IT YIELDS SBCAPE OF ABOUT 400J/KG. IF SFC DWPTS WERE TO REMAIN NEAR CURRENT 60F READINGS...SBCAPE WILL BE UPWARDS OF 1000J/KG. EVEN IF CAPE RISES TO THOSE LEVELS...WITH DEEP LAYER SHEAR AROUND 20KT (SIMILAR TO YESTERDAY)...DO NOT ANTICIPATE ANY SVR STORMS THIS AFTN. AS FOR SHRA COVERAGE...WILL CONTINUE WITH A PCPN FREE FCST FOR THE E WITH A SOMEWHAT MORE STABLE ENVIRONMENT THERE. HOWEVER...WILL NEED TO WATCH THAT AREA CLOSELY AS WEAKER SRLY FLOW WILL KEEP STABILIZATION FROM LAKE MICHIGAN MARINE LAYER MORE LIMITED THAN YESTERDAY. ALSO...IT IS POSSIBLE THAT A LAKE SUPERIOR LAKE BREEZE MAY BE ABLE TO DEVELOP INTO PARTS OF ALGER/LUCE COUNTIES TO PROVIDE A FOCUS FOR CONVECTIVE DEVELOPMENT. TO THE W...LAKE BREEZES SHOULD DEVELOP ACROSS THE KEWEENAW TOWARD FAR NRN BARAGA/MARQUETTE COUNTIES AND PERHAPS TOWARD THE PORCUPINE MOUNTAINS. THIS AREA SHOULD END UP BEING THE FOCUSING AREA FOR CONVECTIVE DEVELOPMENT DURING THE MID/LATE AFTN. && .PREV DISCUSSION (ISSUED AT 420 AM EDT)... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW HI AMPLITUDE PATTERN ACRS NAMERICA WITH TROF OVER THE NRN PLAINS UPSTREAM OF PERSISTENT RDG OVER THE E. SCT SHRA/TSRA THAT DVLPD OVER MAINLY THE W HALF OF THE CWA YDAY WITH ARRIVAL OF WEAK SHRTWV/H5 THERMAL TROF/ PWAT NEAR 1.5 INCHES HAS PRETTY MUCH WANED WITH LOSS OF DIURNAL HTG. SINCE WARM FNT E OF LO ARND INL IS TO THE N...JUST A FEW LINGERING SHRA ARE GOING OVER THE W...WITH JUST SOME LINGERING DEBRIS CLD FARTHER E. LOOKING UPSTREAM...00Z DVN SDNG DEPICTS A DRIER ATMOSPHERE (PWAT 1.01 INCH) THAT AT GRB (PWAT 1.33 INCH). DEEP MIXING TO H75 ON THIS SDNG WOULD CAUSE SFC DWPT TO DROP TO ARND 50 (VS ARND 60 OVER THE FA NOW). IN FACT...VERY LTL IF ANY CNVCTN DVLPD IN THIS AREA YDAY. OAX SDNG IS ALSO DRIER THAN MPX (PWAT 1.35 INCH VS 1.61 INCH AT MPX)...BUT NOT AS DRY AS DVN. OTRW...MORE VIGOROUS CNVCTN IS ONGOING OVER THE NCNTRL PLAINS IN ADVANCE OF MORE POTENT SHRTWV/100KT H3 JET MAX OVER THE CNTRL ROCKIES ROTATING ARND SRN FLANK OF NEARLY CLOSED LO OVER THE NRN PLAINS. MAIN FCST CONCERNS THIS PACKAGE ARE SHRA/TSRA CHCS OVER THE NEXT COUPLE OF DAYS AS UPR LO IN THE PLAINS DRIFTS SLOWLY TO THE E. FOR TDAY...GFS/NAM SHOW DEEP SSW FLOW AHEAD OF SLUGGISH CUTOFF LO IN THE NRN PLAINS. AS STRG SHRTWV ROTATING ARND SYS THIS MRNG DEEPENS THE UPR LO OVER SD TDAY...UPR RDG AXIS FCST TO SHARPEN OVER THE UPR LKS. SINCE H925-85 FLOW FCST TO BACK A BIT IN RESPONSE TO FALLING PRES TO THE W...EXPECT LLVL TRAJECTORIES TO COME FM THE DRIER SOURCE NR DVN. SINCE H925 FLOW IS ALSO FCST TO BE SLGTLY DIFFLUENT AND H5 TEMPS A FEW DEGREES HIER THAN YDAY (ARND -10C VS -12C)...SUSPECT SHRA/TSRA COVG TDAY WL BE LESS THAN YDAY. BEST CHC WOULD SEEM TO BE OVER THE W CLOSER TO SOMEWHAT MORE SUBSTANTIAL MSTR AND WHERE LK BREEZES MIGHT LOCALLY ENHANCE LLVL CNVGC. SINCE PRES GRADIENT/H925 SSW WIND IS FCST TO BE WEAKER TDAY THAN YDAY...LK BREEZE FORMATION LOOKS TO BE MORE LIKELY TDAY. HAVE OPTED TO TAKE OUT POPS OVER THE CNTRL AND RESTRICT MENTION OF 30-40 POPS TO W OF THE HURON MTNS/MQT TO IRON RIVER. MODIFIED GFS FCST SDNG FOR IWD AT 18Z FOR 80/57 YIELDS MLCAPE OF 400 J/KG (COMPARED WITH VALUES CLOSER TO 1000 J/KG YDAY). MIXING TO H75 ON GFS/NAM FCST SDNGS SUPPORTS HI TEMPS NR 83 AWAY FM LK MODERATION. TNGT...FA PROGGED TO REMAIN IN WARM SECTOR OF OCCLUDED LO IN THE NRN PLAINS. SINCE WARM FNT WL BE TO THE N...THINK PCPN CHCS WL BE MINIMAL AFT DIURNAL HTG WANES. ONLY FLY IN THE OINTMENT IS WEAK SHRTWV GFS LIFTS N WELL E OF CLOSED LO IN THE NRN PLAINS. THIS SHRTWV IS CURRENTLY IN THE MID MS RIVER VALLEY...BUT THERE HAVE BEEN ONLY A FEW -SHRA FM MID CLD DECK UNDER THIS SYS. SINCE UKMET/NAM ALSO SHOW THE MOISTENING DEPICTED BY THE GFS...HAVE OPTED TO RETAIN POPS TNGT OVER ALL BUT THE E...WHERE MOISTENING IS FCST TO BE LESS SUBSTANTIAL. SINCE INSTABILITY IS FCST TO BE MARGINAL AT BEST (FCST SSI GENERALLY AOA 0C)...DOWNGRADED POTENTIAL OF TS TO SCHC IN THE ABSENCE OF SGNFT DYNAMICS. OTRW...INCRSG MSTR/CLD COVER WL RESTRICT DIURNAL TEMP FALL...SO TENDED TOWARD THE HIER ETA MOS NUMBERS. LOOKS LIKE SHRA/TSRA CHCS WL INCRS ON THU ESPECIALLY OVER THE W HALF AS GFS/NAM/UKMET/CNDN ALL INDICATE A SHRTWV ROTATING NWD ON THE ERN FLANK OF PARENT CLOSED LO STILL STUCK IN THE NRN PLAINS MOVES INTO NW WI LATE IN THE DAY ALONG WITH ACCOMPANYING 80KT H3 JET MAX. GFS/ NAM FCST SDNGS SUG QUITE A BIT OF MID/HI CLD ASSOCIATED WITH SHRTWV THAT IMPACTS THE FA TNGT WL LINGER THRU THE DAY BEFORE ARRIVAL OF THIS SYS...SO DESTABILIZATION SHOULD NOT BE SGNFT. MODIFIED GFS FCST SDNG FOR 75/60 YIELDS MLCAPE APRCHG 600 J/KG. 0-6KM BULK SHEAR GENERALLY UNDER 25-30 KT AND HI WBZ > 12K FT WITH MARGINAL INSTABILITY SUG SVR THREAT MINIMAL. HOWEVER...OPTED TO BUMP POPS UP TO LIKELY OVER THE W HALF THU AFTN AFT LOWER CHC POPS EARLIER. GFS/UKMET/CNDN MODELS IN PRETTY GOOD AGREEMENT SHOWING DRY SLOTTING BEHIND LIFTING SHRTWV MOVING INTO THE FA SW-NE THU NGT. WL DIMINISH THEN END POPS IN THIS DIRECTION DURING THE NGT AS DRIER AIR ARRIVES. THEN WENT DRY ON FRI MRNG BEFORE INSTABILITY SHRA/TSRA CHCS INCRS AGAIN IN THE AFTN OVER THE W WITH SLOW APRCH OF VORTEX FM THE NRN PLAINS. CONSIDERING TREND TOWARD SLOWER EWD PROGRESSION OF THE CUTOFF...WL KEEP FRI DAY ALL DAY OVER THE E. COORDINATED WITH GRB/APX. && .MARINE (FOR 4 AM ISSUANCE OF LAKE SUPERIOR FCST)... A LOW PRES SYSTEM OVER NORTHERN MINNESOTA WILL GRADUALLY BACK WEST INTO NORTH DAKOTA TODAY AND REMAIN OVER THE CENTRAL DAKOTAS THROUGH FRIDAY. THE LOW WILL TRACK EAST FRIDAY NIGHT REACHING NORTHERN LAKE MICHIGAN ON SATURDAY. THE LOW WILL THEN TRACK INTO SOUTHERN QUEBEC ON SUNDAY. A WEAK COLD FRONT DEVELOPING OVER CENTRAL ONTARIO ON SATURDAY WILL SWEEP ACROSS LAKE SUPERIOR LATE ON SUNDAY. WINDS SHOULD GENERALLY BE BETWEEN 10 TO 15KT AT THE BUOY. OVER THE WEST HALF OF THE LAKE...AS IS TYPICAL IN SOUTHERLY WIND REGIMES OVER A VERY STABLE MARINE LAYER...WINDS WILL AGAIN REMAIN MAINLY EASTERLY NEAR THE MINNESOTA SHORELINE. FOR THE MOST PART... GENERALLY LIGHT WINDS WILL PREVAIL INTO THE UPCOMING WEEKEND AS WEAK PRESSURE GRADIENT WILL BE OVER THE AREA. FOG SHOULD BECOME AN ISSUE THROUGH AT LEAST THURSDAY EVENING ONCE SOME RAINFALL OCCURS OVER THE LAKE AND MOISTENS THE CHILLY MARINE LAYER UNDER SHARP INVERSION. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ AVIATION/UPDATE...ROLFSON PREV DISCUSSION...KC MARINE...DG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 135 PM EDT WED MAY 30 2007 .AVIATION (FOR 18Z TAFS).. SCT SHRA AND A FEW TSRA WILL CONTINUE TO DEVELOP OVER ROUGHLY THE W HALF OF UPPER MI THIS AFTN. OPTED TO INCLUDE A MENTION OF VCNTY THUNDER AT KCMX THIS AFTN AS DEVELOPING LAKE BREEZE SHOULD PROVIDE A FOCUS FOR BETTER CONVECTIVE DEVELOPMENT AROUND THE KEWEENAW PENINSULA. LEFT OUT EXPLICIT MENTION OF THUNDER AT KSAW FOR NOW. EXPECT CONVECTION TO DISSIPATE DURING THE EVENING WITH LOSS OF DAYTIME HEATING. FOG MAY THEN BECOME AN ISSUE LATE EVENING/OVERNIGHT...ESPECIALLY IF RAINFALL OCCURS AT EITHER TAF SITE DURING TEH AFTN/EARLY EVENING. BROUGHT VSBY DOWN MORE AT KCMX (1SM) THAN AT KSAW AS IT APPEARS THERE WILL BE A LIGHT UPSLOPE ESE FLOW THERE OVERNIGHT. DISTURBANCE APPROACHING THU SHOULD BRING A BETTER POTENTIAL FOR SHRA/TSRA TO BOTH TAF SITES. TIMING IS A BIT UNCERTAIN...SO HAVE ONLY INCLUDED A PROB GROUP TOWARD THE END OF TAF PERIOD AT KCMX. PCPN SHOULD ARRIVE JUST BEYOND 18Z AT KSAW. && .UPDATE (ISSUED AT 1100 AM EDT)... MAIN FCST ISSUE THIS AFTN IS SHRA/TSRA POTENTIAL. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A MIDLEVEL LOW CLOSING OFF OVER THE WRN DAKOTAS/ERN MT. THE WRN GREAT LAKES REGION IS WITHIN DEEP LAYERED SW FLOW BTWN THE MIDLEVEL LOW AND THE DOWNSTREAM RIDGE COVERING THE SE STATES TO THE GREAT LAKES. THERE ARE NO DISCERNIBLE SHORTWAVES UPSTREAM THAT WILL AFFECT UPPER MI THIS AFTN. IT HAS BEEN A DRY MORNING ACROSS THE FCST AREA...AND THERE ARE ONLY SOME MID/HIGH CLOUDS PASSING ACROSS UPPER MI. SINCE THERE ARE NO APPARENT SHORTWAVES MOVING TOWARD THE AREA THIS AFTN...WILL NEED TO RELY ON AFTN INSTABILITY FOR SHRA/TSRA DEVELOPMENT. MODIFIED 12Z KGRB SOUNDING FOR AN EXPECTED SFC T/TD OF 85/57F THIS AFTN CAN GET PARCELS JUST PAST A CAP AROUND 600MB...AND IT YIELDS SBCAPE OF ABOUT 400J/KG. IF SFC DWPTS WERE TO REMAIN NEAR CURRENT 60F READINGS...SBCAPE WILL BE UPWARDS OF 1000J/KG. EVEN IF CAPE RISES TO THOSE LEVELS...WITH DEEP LAYER SHEAR AROUND 20KT (SIMILAR TO YESTERDAY)...DO NOT ANTICIPATE ANY SVR STORMS THIS AFTN. AS FOR SHRA COVERAGE...WILL CONTINUE WITH A PCPN FREE FCST FOR THE E WITH A SOMEWHAT MORE STABLE ENVIRONMENT THERE. HOWEVER...WILL NEED TO WATCH THAT AREA CLOSELY AS WEAKER SRLY FLOW WILL KEEP STABILIZATION FROM LAKE MICHIGAN MARINE LAYER MORE LIMITED THAN YESTERDAY. ALSO...IT IS POSSIBLE THAT A LAKE SUPERIOR LAKE BREEZE MAY BE ABLE TO DEVELOP INTO PARTS OF ALGER/LUCE COUNTIES TO PROVIDE A FOCUS FOR CONVECTIVE DEVELOPMENT. TO THE W...LAKE BREEZES SHOULD DEVELOP ACROSS THE KEWEENAW TOWARD FAR NRN BARAGA/MARQUETTE COUNTIES AND PERHAPS TOWARD THE PORCUPINE MOUNTAINS. THIS AREA SHOULD END UP BEING THE FOCUSING AREA FOR CONVECTIVE DEVELOPMENT DURING THE MID/LATE AFTN. && .PREV DISCUSSION (ISSUED AT 420 AM EDT)... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW HI AMPLITUDE PATTERN ACRS NAMERICA WITH TROF OVER THE NRN PLAINS UPSTREAM OF PERSISTENT RDG OVER THE E. SCT SHRA/TSRA THAT DVLPD OVER MAINLY THE W HALF OF THE CWA YDAY WITH ARRIVAL OF WEAK SHRTWV/H5 THERMAL TROF/ PWAT NEAR 1.5 INCHES HAS PRETTY MUCH WANED WITH LOSS OF DIURNAL HTG. SINCE WARM FNT E OF LO ARND INL IS TO THE N...JUST A FEW LINGERING SHRA ARE GOING OVER THE W...WITH JUST SOME LINGERING DEBRIS CLD FARTHER E. LOOKING UPSTREAM...00Z DVN SDNG DEPICTS A DRIER ATMOSPHERE (PWAT 1.01 INCH) THAT AT GRB (PWAT 1.33 INCH). DEEP MIXING TO H75 ON THIS SDNG WOULD CAUSE SFC DWPT TO DROP TO ARND 50 (VS ARND 60 OVER THE FA NOW). IN FACT...VERY LTL IF ANY CNVCTN DVLPD IN THIS AREA YDAY. OAX SDNG IS ALSO DRIER THAN MPX (PWAT 1.35 INCH VS 1.61 INCH AT MPX)...BUT NOT AS DRY AS DVN. OTRW...MORE VIGOROUS CNVCTN IS ONGOING OVER THE NCNTRL PLAINS IN ADVANCE OF MORE POTENT SHRTWV/100KT H3 JET MAX OVER THE CNTRL ROCKIES ROTATING ARND SRN FLANK OF NEARLY CLOSED LO OVER THE NRN PLAINS. MAIN FCST CONCERNS THIS PACKAGE ARE SHRA/TSRA CHCS OVER THE NEXT COUPLE OF DAYS AS UPR LO IN THE PLAINS DRIFTS SLOWLY TO THE E. FOR TDAY...GFS/NAM SHOW DEEP SSW FLOW AHEAD OF SLUGGISH CUTOFF LO IN THE NRN PLAINS. AS STRG SHRTWV ROTATING ARND SYS THIS MRNG DEEPENS THE UPR LO OVER SD TDAY...UPR RDG AXIS FCST TO SHARPEN OVER THE UPR LKS. SINCE H925-85 FLOW FCST TO BACK A BIT IN RESPONSE TO FALLING PRES TO THE W...EXPECT LLVL TRAJECTORIES TO COME FM THE DRIER SOURCE NR DVN. SINCE H925 FLOW IS ALSO FCST TO BE SLGTLY DIFFLUENT AND H5 TEMPS A FEW DEGREES HIER THAN YDAY (ARND -10C VS -12C)...SUSPECT SHRA/TSRA COVG TDAY WL BE LESS THAN YDAY. BEST CHC WOULD SEEM TO BE OVER THE W CLOSER TO SOMEWHAT MORE SUBSTANTIAL MSTR AND WHERE LK BREEZES MIGHT LOCALLY ENHANCE LLVL CNVGC. SINCE PRES GRADIENT/H925 SSW WIND IS FCST TO BE WEAKER TDAY THAN YDAY...LK BREEZE FORMATION LOOKS TO BE MORE LIKELY TDAY. HAVE OPTED TO TAKE OUT POPS OVER THE CNTRL AND RESTRICT MENTION OF 30-40 POPS TO W OF THE HURON MTNS/MQT TO IRON RIVER. MODIFIED GFS FCST SDNG FOR IWD AT 18Z FOR 80/57 YIELDS MLCAPE OF 400 J/KG (COMPARED WITH VALUES CLOSER TO 1000 J/KG YDAY). MIXING TO H75 ON GFS/NAM FCST SDNGS SUPPORTS HI TEMPS NR 83 AWAY FM LK MODERATION. TNGT...FA PROGGED TO REMAIN IN WARM SECTOR OF OCCLUDED LO IN THE NRN PLAINS. SINCE WARM FNT WL BE TO THE N...THINK PCPN CHCS WL BE MINIMAL AFT DIURNAL HTG WANES. ONLY FLY IN THE OINTMENT IS WEAK SHRTWV GFS LIFTS N WELL E OF CLOSED LO IN THE NRN PLAINS. THIS SHRTWV IS CURRENTLY IN THE MID MS RIVER VALLEY...BUT THERE HAVE BEEN ONLY A FEW -SHRA FM MID CLD DECK UNDER THIS SYS. SINCE UKMET/NAM ALSO SHOW THE MOISTENING DEPICTED BY THE GFS...HAVE OPTED TO RETAIN POPS TNGT OVER ALL BUT THE E...WHERE MOISTENING IS FCST TO BE LESS SUBSTANTIAL. SINCE INSTABILITY IS FCST TO BE MARGINAL AT BEST (FCST SSI GENERALLY AOA 0C)...DOWNGRADED POTENTIAL OF TS TO SCHC IN THE ABSENCE OF SGNFT DYNAMICS. OTRW...INCRSG MSTR/CLD COVER WL RESTRICT DIURNAL TEMP FALL...SO TENDED TOWARD THE HIER ETA MOS NUMBERS. LOOKS LIKE SHRA/TSRA CHCS WL INCRS ON THU ESPECIALLY OVER THE W HALF AS GFS/NAM/UKMET/CNDN ALL INDICATE A SHRTWV ROTATING NWD ON THE ERN FLANK OF PARENT CLOSED LO STILL STUCK IN THE NRN PLAINS MOVES INTO NW WI LATE IN THE DAY ALONG WITH ACCOMPANYING 80KT H3 JET MAX. GFS/ NAM FCST SDNGS SUG QUITE A BIT OF MID/HI CLD ASSOCIATED WITH SHRTWV THAT IMPACTS THE FA TNGT WL LINGER THRU THE DAY BEFORE ARRIVAL OF THIS SYS...SO DESTABILIZATION SHOULD NOT BE SGNFT. MODIFIED GFS FCST SDNG FOR 75/60 YIELDS MLCAPE APRCHG 600 J/KG. 0-6KM BULK SHEAR GENERALLY UNDER 25-30 KT AND HI WBZ > 12K FT WITH MARGINAL INSTABILITY SUG SVR THREAT MINIMAL. HOWEVER...OPTED TO BUMP POPS UP TO LIKELY OVER THE W HALF THU AFTN AFT LOWER CHC POPS EARLIER. GFS/UKMET/CNDN MODELS IN PRETTY GOOD AGREEMENT SHOWING DRY SLOTTING BEHIND LIFTING SHRTWV MOVING INTO THE FA SW-NE THU NGT. WL DIMINISH THEN END POPS IN THIS DIRECTION DURING THE NGT AS DRIER AIR ARRIVES. THEN WENT DRY ON FRI MRNG BEFORE INSTABILITY SHRA/TSRA CHCS INCRS AGAIN IN THE AFTN OVER THE W WITH SLOW APRCH OF VORTEX FM THE NRN PLAINS. CONSIDERING TREND TOWARD SLOWER EWD PROGRESSION OF THE CUTOFF...WL KEEP FRI DAY ALL DAY OVER THE E. COORDINATED WITH GRB/APX. && .MARINE (FOR 4 AM ISSUANCE OF LAKE SUPERIOR FCST)... A LOW PRES SYSTEM OVER NORTHERN MINNESOTA WILL GRADUALLY BACK WEST INTO NORTH DAKOTA TODAY AND REMAIN OVER THE CENTRAL DAKOTAS THROUGH FRIDAY. THE LOW WILL TRACK EAST FRIDAY NIGHT REACHING NORTHERN LAKE MICHIGAN ON SATURDAY. THE LOW WILL THEN TRACK INTO SOUTHERN QUEBEC ON SUNDAY. A WEAK COLD FRONT DEVELOPING OVER CENTRAL ONTARIO ON SATURDAY WILL SWEEP ACROSS LAKE SUPERIOR LATE ON SUNDAY. WINDS SHOULD GENERALLY BE BETWEEN 10 TO 15KT AT THE BUOY. OVER THE WEST HALF OF THE LAKE...AS IS TYPICAL IN SOUTHERLY WIND REGIMES OVER A VERY STABLE MARINE LAYER...WINDS WILL AGAIN REMAIN MAINLY EASTERLY NEAR THE MINNESOTA SHORELINE. FOR THE MOST PART... GENERALLY LIGHT WINDS WILL PREVAIL INTO THE UPCOMING WEEKEND AS WEAK PRESSURE GRADIENT WILL BE OVER THE AREA. FOG SHOULD BECOME AN ISSUE THROUGH AT LEAST THURSDAY EVENING ONCE SOME RAINFALL OCCURS OVER THE LAKE AND MOISTENS THE CHILLY MARINE LAYER UNDER SHARP INVERSION. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ AVIATION/UPDATE...ROLFSON PREV DISCUSSION...KC MARINE...DG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 1204 PM CDT WED MAY 30 2007 .UPDATE... CLOUDS THINNED OUT ACROSS THE AREA. SATELLITE SHOWS A DRY SLOT PIVOTING THROUGH THE REGION. THE LARGE CONVECTIVE COMPLEX WAS STEADILY MOVING SOUTH AND EAST...WILL BE WATCHING CLOSELY FOR IMPACTS TO THE CWA. THE LINE OF STORMS WERE MOVING QUICKLY. BREAKS IN THE CLOUDS ALLOWED TEMPERATURES TO CLIMB IN A FEW SPOTS...SO RAISED TEMPS A DEGREE OR TWO...IN AREAS ORIENTED ALONG THE NATCHEZ TRACE. THE SYSTEM TO THE SOUTH HAD NOT PROGRESSED NORTH MUCH...SO BEST RAIN WAS STILL JUST OUTSIDE THE CWA. ACTIVITY TO THE NORTH CONTINUES TO DISSIPATE AS IT MOVES OUT OF THE AREA...SO ONLY A SMALL AREA OF LIGHT RAIN LINGERING OVER THE SOUTHEAST PORTIONS OF THE CWA AT THIS POINT. RUC SHOWS A LITTLE BIT OF INSTABILITY OVER THE SOUTHEAST...BUT OF COURSE THE BEST OF EVERYTHING IS STILL WEST. COULD NOT JUSTIFY ANY CHANGES TO THE POPS...ALTHOUGH THE VALUES WERE HIGH. SHOWERS CONTINUE TO POP UP AROUND THE CWA...SO WILL MAINTAIN THE CURRENT VALUES FOR NOW. ADJUSTED WORDING FOR COVERAGE. MORNING SOUNDING SHOWS AROUND 1.5IN PW...BUT A DECENT DRY LAYER IN THE LOWER LEVELS. HOWEVER SOUTHWEST FLOW AROUND 30-40KTS IN THE LOW TO MID LEVELS WILL HELP BRING MORE OF THE GULF MOISTURE INTO THE REGION. MAY ADD A FEW LINES TO THE HWO ABOUT STRONG STORMS...COULD SEE SOME GOOD WINDS IF THE SQUALL LINE SWINGS THROUGH THE AREA. LAPSE RATES WERE NOT TOO STEEP...SO WILL FOCUS ON WINDS. OTHERWISE THE FORECAST WAS OK. && .AVIATION... VFR TO MVFR CONDITIONS WILL PREVAIL THROUGH THE EARLY AFTERNOON...WITH SOME UNCERTAINTIES IN THE DIRECTION OF THE COMPLEX TO THE WEST AND ITS INTENSITY IF IT REACHES THE AREA...WILL MAINTAIN SHRA AND VCTS FOR GLH/GWO/JAN AT THIS POINT. WILL KEEP SIMILAR TIMING AROUND 21Z. STORMS CONTINUE TO DEVELOP OVER SOUTH LOUISIANA...SO WILL MAINTAIN VCTS FOR HBG ALSO. RAIN ACTIVITY WILL BE MOSTLY SCATTERED IN NATURE FOR MOST OF THE AFTERNOON...SO WILL KEEP SHRA IN AT ALL SITES THROUGH THE EVENING. SHOULD SEE THE ACTIVITY TAPER OFF OVERNIGHT...BUT ISOLATED SHOWERS WILL LIKELY CONTINUE. WILL LIKELY CONTINUE FOG TONIGHT ALSO. WINDS PICKED UP IN A FEW SPOTS...NOT EXPECTING CONDITIONS TO REACH ADVISORY CONDITIONS...BUT WINDS 10-15KTS WITH OCCASIONAL GUSTS AROUND 20 CAN BE EXPECTED THROUGH THE AFTERNOON...BECOMING LIGHT LATE IN THE EVENING. SHOWERS WILL DEVELOP EARLY AGAIN ON THURSDAY AND CONTINUE OFF AND ON THROUGH THE PERIOD...SO WILL BRING SHRA BACK INTO ALL SITES AROUND 13Z. OCCASIONAL THUNDERSTORMS MAY BRING SOME HIGHER GUSTS...HEAVY RAIN MAY ALSO REDUCE VISIBILITIES BRIEFLY...BUT OVERALL VFR/MVFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE PERIOD. CEILINGS REMAIN ABOVE 3KFT AND WILL MAINTAIN THROUGH AT LEAST 00Z AT MOST SITES. MAY ADD LOWER CLOUDS BRIEFLY FOR THUNDERSTORMS AND POSSIBLE FOG/STRATUS OVERNIGHT. && .PRELIMINARY POINT TEMPS/POPS... JACKSON 81 66 81 66 / 71 50 48 21 MERIDIAN 78 64 81 64 / 64 46 38 15 VICKSBURG 84 67 83 66 / 90 50 46 22 HATTIESBURG 78 67 80 66 / 80 53 52 23 NATCHEZ 81 67 82 66 / 81 50 47 22 GREENVILLE 82 67 83 65 / 91 49 36 16 GREENWOOD 80 67 83 66 / 81 47 40 15 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ 7 ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HASTINGS NE 411 PM CDT WED MAY 30 2007 .SHORT TERM...THROUGH 12Z FRIDAY. MAIN FOCUS IS ON THUNDERSTORM CHANCES THURSDAY AND THURSDAY NIGHT AND ATTENDANT SEVERE POTENTIAL. AFTERNOON WATER VAPOR IMAGERY SHOWS THE LARGE CUTOFF UPPER LOW CONTINUING TO SPIN OVER THE NORTHERN ROCKIES AND PLAINS WITH SEVERAL VORT MAXES ROTATING AROUND THE PARENT CIRCULATION. THE SURFACE COLD FRONT HAS SHIFTED WELL EAST OF THE AREA...NOW RUNNING ROUGHLY NORTH/SOUTH FROM EASTERN SOUTH DAKOTA INTO EASTERN OKLAHOMA. LOW CLOUDS AND SHOWERS HAVE MAINLY PUSHED EAST OF THE CWA AS A VORT LOBE CONTINUES TO PUSH NORTHEAST ACROSS CENTRAL NEBRASKA. SUBSIDENCE BEHIND THE WAVE HAS RESULTED IN PERIODS OF BRIEF CLEARING OVER THE CWA...WITH STRATOCU FILLING IN QUICKLY BEHIND. THE CUTOFF UPPER LOW MOVES LITTLE OVER THE NEXT COUPLE DAYS...CONTINUING TO SPIN OVER THE NORTHERN PLAINS. THE MAIN QUESTION FOR TONIGHT IS WHETHER ANY SHOWERS/THUNDERSTORMS CURRENTLY DEVELOPING OVER THE HIGH PLAINS WILL MAKE IT EAST INTO THE CWA. THE NAM/GFS/RUC ALL INDICATE THAT SOME WEAK SHOWERS MAY MAKE IT INTO THE NORTHWEST THIS EVENING BEFORE DISSIPATING BEFORE MIDNIGHT...AND WITH SUPPORT FROM CURRENT OBSERVATIONAL DATA AND SOUTHEAST MOVEMENT...HAVE INSERTED SOME SLIGHT CHANCE POPS FOR THE EVENING HOURS. WITH FAIRLY STABLE CONDITIONS IN PLACE AND SHOWERS/STORMS EXPECTED TO BE ON THE DECLINE BEFORE MAKING IT THIS FAR EAST...DECIDED TO JUST GO WITH SHOWERS VERSUS THUNDERSTORMS. BETTER PRECIPITATION CHANCES RETURN THURSDAY AS ANOTHER MID-LEVEL SHORTWAVE ROUNDS THE UPPER LOW AND SLIDES ACROSS THE AREA. THIS SHOULD PROVIDE AMPLE FORCING TO TRIGGER CONVECTION...SOME OF WHICH MAY REACH STRONG TO SEVERE LIMITS DURING THE AFTERNOON AND EARLY EVENING. MOISTURE RETURN WILL BE LIMITED WITH SFC DEWPOINTS ONLY EXPECTED TO REACH THE LOWER 50S...BUT COLD MID-LEVEL TEMPS ASSOCIATED WITH THE UPPER LOW AND RESULTANT STEEP LAPSE RATES WILL COMPENSATE FOR THIS TO PRODUCE CAPES AROUND 1000 J/KG. DEEP-LAYER SHEAR OF 40-50 KTS WILL BE MORE THAN ADEQUATE TO SUPPORT SEVERE CONVECTION. MAIN THREAT LOOKS TO BE LARGE HAIL GIVEN COLD TEMPS ALOFT ALTHOUGH STRONG WINDS WILL BE POSSIBLE AS WELL. A SURFACE BOUNDARY GETS SHOVED SOUTH THROUGH THE AREA THURSDAY NIGHT...WITH BETTER PRECIP CHANCES SHIFTING SOUTH THROUGH THE NIGHT IN RESPONSE. TEMPERATURES REBOUND SOMEWHAT TOMORROW AS H85 TEMPS CLIMB INTO THE LOWER TO MID TEENS BUT CLOUD COVER WILL TEMPER HEATING SOMEWHAT. .LONG TERM...FRIDAY MORNING THROUGH NEXT WEDNESDAY THE MODELS CONTINUE TO SHOW THE LARGE CUT OFF UPPER CYCLONE OVER THE NORTHERN PLAINS...SLOWLY SHIFTING EAST INTO THE GREAT LAKES BY MONDAY. INITIALLY THIS WAVE WILL BRING AN ADDITIONAL CHANCE OF SHOWERS AND THUNDERSTORMS ON FRIDAY AS A COLD FRONT IS SHOWN TO PUSH THROUGH THE REGION. SOME POSSIBILITY WITH THIS FRONT FOR SEVERE CONVECTION...ALTHOUGH MOST OF THIS SHOULD BE LIMITED TO EARLY ON FRIDAY. MAIN QUESTION FOR THIS PERIOD INVOLVES NEXT TUESDAY AND WEDNESDAY AS THE MEDIUM RANGE MODELS ARE VARYING THE PATTERN OVER THE CENTRAL CONUS FROM A FAIRLY ZONAL REGIME PER 12Z GFS...TO A LARGE NORTHERN STREAM WAVE RIDING ACROSS THE PLAINS. THE DIFFERENCE IN THE UPPER PATTERN IS HUGE FOR THE PLAINS AS THE FIRST SOLUTION WOULD BE LITTLE CHANCE OF PRECIP AND HOT...WHILE THE SECOND SOLUTION WOULD BE WET AND COOLER. AT THIS POINT...CONFIDENCE IN EITHER SOLUTION IS LOW AND WILL INSERT A LOW CHANCE OF PRECIP BUT KEEP TEMPERATURES NEAR TO ABOVE NORMAL. && .AVIATION...SHORTWAVE ROTATING AROUND MEAN UPPER LOW OVER THE NORTHERN ROCKIES/PLAINS CONTINUES TO PUSH NORTHEAST ACROSS CENTRAL NEBRASKA THIS AFTERNOON. THIS WILL PUSH THE SHOWER ACTIVITY TO THE NORTHEAST AS WELL...AND BELIEVE SHOWERS WILL REMAIN NORTH OF THE KGRI TERMINAL AS A RESULT...ALTHOUGH SOME WILL BE IN THE VICINITY EARLY THIS AFTERNOON. LOWER CEILINGS WILL CONTINUE TO CLEAR FROM SOUTHWEST TO NORTHEAST AS INDICATED BY LATEST SATELLITE IMAGERY...WITH SCATTERED VFR CLOUDS FILLING IN BEHIND. MAY SEE PERIODS OF BROKEN CEILINGS THROUGH THE AFTERNOON AS STRATOCU FILLS IN...BUT THEY LOOK TO REMAIN VFR. BREEZY NORTHWEST WINDS WILL GRADUALLY WEAKEN THIS AFTERNOON AS THE SURFACE PRESSURE GRADIENT WEAKENS. NEXT IMPACT WILL BE SOME POSSIBLE THUNDERSTORMS LATE IN THE TAF PERIOD THURSDAY MORNING...AND HAVE COVERED WITH A PROB GROUP FOR NOW AS EXACT TIMING OF WHEN THE STORMS WILL GET INTO THE AREA REMAINS UNCERTAIN. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN ANGELO TX 315 PM CDT WED MAY 30 2007 .SHORT TERM... AN ALL OR NOTHING TYPE OF EVENT FOR WEST CENTRAL TEXAS UPCOMING... AND PLAYING THE WAITING GAME RIGHT NOW. SURFACE BASED CAPES HAVE CLIMBED ABOVE 3500 ALREADY...WITH THE 18Z RUC SHOWING EVEN BETTER INSTABILITY LATER THIS AFTERNOON. CAP HAS HELD SO FAR...BUT CU HAS STARTED TO DEVELOP. MAY BE A FEW MORE HOURS...BUT THINK AT LEAST SCATTERED STORMS WILL DEVELOP THIS AFTERNOON AND EVENING...AND GIVEN THE INSTABILITY...MAY QUICKLY REACH SEVERE LEVELS. NEXT QUESTION IS WHERE? FRONTAL BOUNDARY DRAPED BETWEEN SWEETWATER AND ABILENE...WITH SOMEWHAT ILL DEFINED DRYLINE EXTENDING SOUTH ACROSS THE CONCHO VALLEY AND NORTHERN EDWARDS PLATEAU. ALSO WATCHED THE VERY BACK EDGE OF AN OUTFLOW BOUNDARY CREEP INTO THE EASTERN COUNTIES EARLIER THIS AFTERNOON. COULD SEE THE STORMS DEVELOP ANYWHERE ALONG ANY OF THESE BOUNDARIES...BUT AREAS ACROSS THE COLD FRONT ACROSS THE BIG COUNTRY PROBABLY THE MOST LIKELY. THEN WE WILL SEE IF A MORE WIDESPREAD COMPLEX CAN END UP FORMING. WILL CONTINUE THE SMALL POPS FOR THURSDAY AND THURSDAY NIGHT...AS FRONTAL BOUNDARY BEGINS TO WASH OUT. CAP SHOULD BE A LITTLE WEAKER AND SHOULD HAVE PLENTY OF INSTABILITY...BUT GETTING SOME SORT OF SURFACE CONVERGENCE TO BREAK THROUGH THE REMAINING CAP MAY STILL BE TOUGH. WILL NEED TO SEE WHATS LEFT OF THE FRONTAL BOUNDARY AND WHERE ANY OUTFLOW BOUNDARIES WILL END UP. .LONG TERM... NORTHWEST FLOW BECOMES ESTABLISHED ACROSS THE SOUTHERN PLAINS...WITH A SERIES OF SHORTWAVES DROPPING THROUGH. HARD TO RULE OUT CONVECTIVE DEVELOPMENT IN NORTHWEST FLOW...WITH EITHER STUFF DEVELOPING WELL TO THE NORTHWEST ROLLING IN SATURDAY... SUNDAY...OR EVEN MONDAY NIGHT...OR AT LEAST SHOVING BOUNDARIES DOWN OUR DIRECTION. WILL CONTINUE TO MENTION SLIGHT CHANCE TO CHANCE POPS...WITH BETTER ODDS ACROSS THE BIG COUNTRY. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 68 88 68 86 / 30 20 20 20 SAN ANGELO 68 91 68 89 / 30 20 20 10 JUNCTION 71 89 68 87 / 30 10 10 10 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 07 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN ANGELO TX 1225 PM CDT WED MAY 30 2007 .AVIATION...OVERALL REDUCED POSSIBILITIES IN THE TAFS OF THUNDERSTORM DEVELOPMENT. STILL CAN NOT RULE OUT THUNDERSTORM DEVELOPMENT NORTHEAST OF A LINE FROM KSJT TO KJCT. WILL CONTINUE TO MENTION ONLY A PROB30 AFTER 03Z FOR KABI AND KBBD AS THESE LOCATIONS IN THE BEST LOCATION FOR TSRA DEVELOPMENT. OTHERWISE WILL NOT MENTION IN THE OTHER TAFS AS WE ARE NOT THAT CONFIDENT. MAY NEED TO AMEND AS WE SEE HOW THINGS DEVELOP. OTHERWISE...WINDS WILL BE ALL OVER THE PLACE WITH OUTFLOW BOUNDARIES MOVING THROUGH THE AREA. COLD FRONT CURRENTLY BETWEEN KSWW AND KABI WILL BE SLOW TO MOVE THROUGH THE DAY UNTIL NEW THUNDERSTORMS POSSIBLY DEVELOP ALONG IT THIS AFTERNOON. UNTIL FROPA...WINDS WILL BE RATHER VARIABLE. BRAZZELL && .PREV DISCUSSION... /ISSUED 1107 AM CDT WED MAY 30 2007/ UPDATE...HAVE UPDATED FORECAST TO REMOVE POPS TO THE SOUTHWEST FOR THE DAY AS THIS AREA IS IN THE MUCH STRONGER CAP AND DOUBT ANYTHING WILL DEVELOP SOUTHWEST OF A STERLING CITY TO SAN ANGELO TO SAN SABA LINE. ALSO PUSHED BACK TIMING OF THUNDERSTORM DEVELOPMENT TO THE NORTHWEST OF THAT LINE TIL AFTER 21Z AS WE HAVE TO WEAKEN THE CAP AND GET THE FRONT A LITTLE FURTHER TO THE SOUTH FOR BETTER CONVERGENCE. IF THUNDERSTORMS DO GET GOING THIS AFTERNOON...RUC FORECAST CAPES TO BE 4 TO 6 THOUSAND J/KG AND STORMS WILL LIKELY BE SEVERE. SO WENT AHEAD AND MENTIONED SEVERE FOR THIS AFTERNOON WHERE WE THINK STORMS WILL DEVELOP. ALSO COOLED TEMPERATURES ACROSS THE BIG COUNTRY...WHERE CLOUDS AND OUTFLOWS AND SOME FRONTAL EFFECTS WILL KEEP TEMPERATURES A LITTLE COOLER. FURTHER TO THE SOUTH WHERE THE STRONG CAP IS IN PLACE AND LESS EFFECTS FROM CLOUDS...OUTFLOWS AND FRONT...HAVE INCREASED TEMPERATURES A LITTLE. UPDATES TO FLY SOON. BRAZZELL PREV DISCUSSION... /ISSUED 611 AM CDT WED MAY 30 2007/ AVIATION... AREAS OF MVFR CIGS BKN015-025 ARE EXPECTED UNTIL 30/17Z ACROSS WEST CENTRAL TEXAS. MAINLY VFR CONDITIONS ARE EXPECTED AFTER 30/17Z. A THUNDERSTORM OUTFLOW BOUNDARY WILL MOVE INTO THE BIG COUNTRY THIS MORNING...AND THEN STALL OUT. SCATTERED TSTMS WILL DEVELOP ACROSS BIG COUNTRY NEAR THE BOUNDARY AFTER 30/20Z. ISOLD TSTMS WILL BE POSSIBLE ACROSS THE REMAINDER OF WEST CENTRAL TEXAS AFTER 30/20Z. 21 PREV DISCUSSION... /ISSUED 302 AM CDT WED MAY 30 2007/ SHORT TERM... COLD FRONT SOUTH OF AMARILLO AT 3 AM LIKELY TO MOVE SOUTH INTO THE BIG COUNTRY THIS MORNING AHEAD OF SCHEDULE...WITH A EXTRA PUSH FROM OUTFLOW FROM STRONG/SEVERE STORMS MOVING INTO WESTERN OKLAHOMA. WITH WRF SB CAPES OF 4000 J/KG BY MID AFTERNOON IN THE BIG COUNTRY...MAY SEE A FEW SEVERE THUNDERSTORMS. WILL MENTION SEVERE IN BIG COUNTRY ZONES TONIGHT. WRF MODEL HANGS UP FRONT ALONG I-20 TONIGHT...BEFORE LIFTING NORTH FRIDAY...BUT ACTUAL POSITION DEPENDS ON CONVECTION AND OUTFLOW BOUNDARIES THAT MAY DRIVE IT SOUTHWARD. A FEW THUNDERSTORMS ALSO POSSIBLE ON DRYLINE THAT WILL BE DEVELOPING IN CROCKETT COUNTY AND THE WESTERN CONCHO VALLEY IN THE AFTERNOON...THEN MOVE EAST IN THE EVENING. THIS A LESS LIKELY...BUT STILL POSSIBLE. CAP HAS BEEN HARD TO ERODE THE LAST COUPLE DAYS...EVEN THOUGH MODELS INDICATE LITTLE/NO CAP BY AFTERNOON. LONG TERM... UNSTABLE IN THE BIG COUNTRY AND EASTERN SECTIONS OF THE CWA ON FRIDAY. THURSDAY NIGHTS CONVECTION...THUNDERSTORM OUTFLOW BOUNDARIES WILL INFLUENCE RAIN CHANCES...BUT BEST CHANCES AROUND 30 PERCENT WILL AGAIN BE IN THE BIG COUNTRY. NORTHWEST UPPER LEVEL FLOW PATTERN DEVELOPS FRIDAY INTO THE WEEKEND. MAY SEE EVENING OROGRAPHIC CONVECTION DEVELOP IN THE MOUNTAINS AND PANHANDLE...THEN MOVE SOUTHEAST INTO LOW LEVEL FLOW. CHANCES OF IT REACHING THE BIG COUNTRY OR FURTHER SOUTH INTO THE CONCHO VALLEY ARE LOW EARLY FRIDAY AND SATURDAY MORNING...BUT POSSIBLE. RAIN CHANCES HOWEVER INCREASE EARLY SUNDAY AS ANOTHER COLD FRONT MOVES INTO REGION...WITH THE POTENTIAL FOR SEVERAL THUNDERSTORM COMPLEXES. HIGHER THAN NORMAL RAIN CHANCES CONTINUE INTO MONDAY. WARMER AND DRIER TUESDAY INTO WEDNESDAY AS AN UPPER RIDGE BUILDS INTO THE REGION. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 85 68 88 68 / 30 30 20 20 SAN ANGELO 92 68 91 68 / 10 20 20 20 JUNCTION 92 71 89 68 / 10 20 10 10 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 27/27/99 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 218 PM MDT WED MAY 30 2007 .SHORT TERM...TONIGHT THROUGH SATURDAY OBLONG SHAPED UPPER LOW OVER THE NORTHWEST HIGH PLAINS THIS AFTERNOON. THE NORTHERN PIECE ROTATING TO THE SOUTHWEST WHICH LOOKS TO MOVE THROUGH WYOMING LATE TONIGHT INTO THURSDAY AFTERNOON. COLD FRONT MOVED INTO NORTHERN WYOMING EARLIER THIS MORNING AND HAS BEEN MOVING SOUTH AND WEST AS THE AFTERNOON PROGRESSED. WEAK INSTABILITY OVER THE NORTHEAST ZONES THIS AFTERNOON WHERE ISOLATED THUNDERSTORMS HAVE BEEN FIRING. BIG HORNS AND JOHNSON COUNTY WILL CONTINUE TO SEE THE HIGHEST THREAT FOR SHOWERS AND THUNDERSTORMS THIS EVENING...THOUGH NORTH AND CENTRAL COULD SEE ISOLATED ACTIVITY. THE SECONDARY VORT LOBE TO MOVE INTO WYOMING LATE TONIGHT AND WORK ITS WAY SOUTH AND EAST ACROSS THE STATE THURSDAY. SHOULD SEE ENOUGH LOW LEVEL STABILITY TO KEEP THUNDER OUT OF FORECAST THURSDAY. HOWEVER...MODELS SHOWING DECENT AMOUNTS OF MOISTURE BACKING INTO JOHNSON COUNTY. THIS SHOULD BRING AT LEAST SCATTERED SHOWER ACTIVITY TO THE AREA BEGINNING TOMORROW AFTERNOON. SHIED AWAY FROM INCREASING POPS TOO MUCH AS THE MODELS WERE ADVERTISING DECENT QPF TO THE AREA THIS MORNING AND GOT NOTHING. SO WILL WAIT AND SEE HOW THE MODELS PROGRESS TONIGHT AND TOMORROW MORNING. THIS MOIST FLOW CONTINUES INTO THURSDAY NIGHT AND FRIDAY MORNING...EXITING FRIDAY AFTERNOON. UPPER LOW FINALLY TO BEGIN MOVING EASTWARD SATURDAY AS NEXT PACIFIC SYSTEM BEGINS TO PUSH THE RIDGE FURTHER EAST. NORTHWEST TO NORTH FLOW REMAINS OVER WYOMING SATURDAY WITH SOME MOISTURE BEGINNING TO RIDE OVER THE RIDGE INTO NORTHWEST WYOMING. SO WILL KEEP THE GOING FORECAST OF SLIGHT CHANCE OF THUNDERSTORMS THERE. TEMPERATURES OVER THE NEXT FEW DAYS TO REMAIN COOL EAST OF THE DIVIDE...WHILE WARMING TO NEAR NORMALS WEST AND SOUTHWEST. .LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY NOT MUCH CHANGE IN THE OVERALL WEATHER PATTERN SATURDAY NIGHT AND SUNDAY WITH NORTHWEST FLOW ALOFT OVER THE AREA. SEEMS TO BE ENOUGH MOISTURE IN THE FLOW WITH WEAK DISTURBANCES ALOFT. LOW LEVEL FORCING WILL ALSO OCCUR NEAR MOUNTAINS. THUS KEEPING THE ISOLATED AFTERNOON AND EVENING SHOWERS AND STORMS IN THE FORECAST SAT AND SUN. UPPER RIDGE AXIS SLIDES OVER WY ON MONDAY AS A NEW TROUGH MOVES INTO THE PACIFIC NORTHWEST STATES. AGAIN ISOLATED MOUNTAIN CONVECTION IN THE WEST SEEMS REASONABLE. GFS IS FASTER ON TUE WITH MOVING A PART OF THE TROUGH THROUGH THE NORTHERN ROCKIES WITH A COLD FRONT INTO NW WY TUE PM. THE ECMWF IS SLOWER AND HOLDS OFF ANY FRONTAL PUSH UNTIL TUE NIGHT. WILL PLAY SLOWER SOLUTION FOR NOW AND KEEPING SOME LOW CHANCES OF PRECIP OVER THE WESTERN MTS AND THE BIG HORN MTS TUE AND TUE NIGHT. IF THE SLOWER ECMWF SOLUTION PANS OUT THEN WED WILL SEE SOME CONVECTION. IF THE GFS IS ON TARGET IT WOULD BE MOSTLY DRY NEXT WED. WILL TACKLE THAT TONIGHT AND LEAVE FORECAST DRY FOR NOW. AS FOR TEMPS...STILL THINKING IT WILL GRADUALLY WARM OVER THE WEEKEND INTO EARLY NEXT WEEK AHEAD OF THE NEXT TROUGH. HAVE MADE SLIGHT ADJUSTMENTS TO GOING FORECAST HIGHS AND LOWS. && .AVIATION... NORTHWEST UPPER LEVEL FLOW TO PREVAIL THROUGH THE FORECAST PERIOD. SEVERAL TAF LOCATIONS WILL EXPERIENCE GUSTY NORTHWEST SURFACE WIND INTO THE EARLY EVENING WITH A REPEAT EXPECTED THURSDAY AS THE BOUNDARY LAYER MIXES. HAVE LEFT -TSRA OUT OF TAFS FOR THIS AFTERNOON AND EVENING BUT HAVE KEPT MENTION IN NORTHERN TWEB ROUTES. CURRENT RUC FORECASTS INDICATE BETTER MOISTURE AND INSTABILITY TO REMAIN MAINLY NORTH OF A LINE FROM AROUND YELLOWSTONE NATIONAL PARK TO KCPR. A BETTER NORTHERLY SURGE ANTICIPATED EAST OF THE DIVIDE THURSDAY AFTERNOON AS ANOTHER DISTURBANCE PINWHEELS AROUND UPPER LOW. THIS HAS NECESSITATED SLIGHT INCREASE IN AFTERNOON WIND SPEEDS WHILE KEEPING -SHRA CONFINED TO SAME AREAS AS TODAY. VFR CIGS AND VSBYS ANTICIPATED THROUGH THE PERIOD. THE EXCEPTION WILL BE LOCALIZED MVFR IN ASSOCIATION WITH STRONGEST CONVECTION MAINLY OVER JOHNSON AND NATRONA COUNTIES. AN ADDITIONAL NOTE FOR A NON-TAF SITE...TIGHTENING PRESSURE GRADIENT WILL INCREASE NORTHWEST SURFACE WIND AROUND KBYG TO 25G40+ KTS LATE TONIGHT THROUGH THURSDAY. && .FIRE WEATHER... UPPER LOW OVER THE NORTHWEST HIGH PLAINS WILL KEEP RELATIVELY MOIST NORTHWEST TO NORTH FLOW OVER WYOMING THROUGH THE REMAINDER OF THE WEEK INTO THE WEEKEND. A FEW SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE OVER THE EASTERN AND NORTHERN ZONES TODAY AND THURSDAY. BREEZY TO WINDY NORTH WINDS ARE EXPECTED OVER SHERIDAN AND JOHNSON COUNTIES TODAY AND TOMORROW. OVER THE WEST AND SOUTH...MOSTLY DRY AND WARMING CONDITIONS ARE EXPECTED AND LOWERING RH`S AS WELL. && .RIW WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...TWB LONG TERM...AR AVIATION...CNJ FIRE WEATHER...TWB wy