AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 408 AM MDT THU SEP 4 2008 .SHORT TERM... (TODAY AND TONIGHT) SHORT TERM CONCERN IS AMOUNT AND STRENGTH OF CONVECTION LATE THIS AFTERNOON AND OVERNIGHT WITH PASSING UPPER TROUGH. CURRENT WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSIS INDICATING GENERALLY WEAK WEST TO NORTHWEST FLOW ALOFT ACROSS THE STATE WITH A BROAD UPPER TROUGH MOVING ACROSS THE NORTHERN TIER OF STATES ATTM. WATER VAPOR ALSO INDICATING AN EMBEDDED SHORT WAVE MOVING ACROSS NORTHERN WYOMING WITH ANOTHER WAVE MOVING ACROSS THE PAC NW COAST ATTM. WYOMING WAVE SPREADING A FEW HIGH CLOUDS ACROSS NORTHERN COLORADO WITH REGIONAL SATELLITE PICS INDICATING GENERALLY CLEAR SKIES ELSEWHERE ACROSS THE STATE ATTM. TODAY...NORTHERN WYOMING SHORT WAVE CONTINUES TO LIFT OUT ACROSS THE NORTHERN HIGH PLAINS WITH LATEST MODELS CONTINUING TO INDICATE INCREASING WEST TO NORTHWEST FLOW ALOFT ACROSS THE STATE AS PAC NW WAVE AND 80+KT JET DIGS INTO WESTERN WYOMING AND EXTREME NORTHWEST COLORADO THROUGH THE LATE AFTERNOON. PASSING WYOMING WAVE ALLOWS FOR A WEAK NORTHERLY SURGE ACROSS THE PLAINS THROUGH THE EARLY MORNING HOURS WITH LOW LEVEL WINDS BECOMING INCREASING EAST TO SOUTHEAST WITH LOWERING PRESSURES ACROSS THE EASTERN MTS AHEAD OF NEXT WAVE. LATEST NAM INDICATING DEW PTS IN THE MID 30S TO MID 40S ACROSS THE I-25 CORRIDOR AND EASTERN PLAINS THIS AFTERNOON WITH CAPES GENERALLY LESS THAN 500J/KG WITH BEST INSTABILITY ALONG WITH SOUTHEAST MTS. HAVE KEPT CURRENT SLIGHT POPS ACROSS THE EASTERN MTS AND ALONG THE PALMER DVD LATE THIS AFTERNOON...AND WITH THE INCREASING FLOW ALOFT AND BULK SHEARS INCREASING TO BETWEEN 30 AND 40 KTS...COULD SEE A FEW STRONGER STORMS ALONG THE SOUTHEAST MTS IF CONVECTION CAN INITIATE. WITH MORE SUNSHINE EXPECTED TODAY...HAVE LEANED CLOSER TO THE WARMER SIDE OF GUIDANCE WITH HIGHS WARMING INTO THE MID 70S TO LOWER 80S ACROSS THE PLAINS AND INTO THE 50S TO LOWER 70S ACROSS THE HIGHER TERRAIN AND HIGH VALLEYS. TONIGHT...MODELS CONTINUE TO ADVERTISE WESTERN WYOMING SHORT WAVE MOVING OUT ACROSS SOUTHERN WYOMING AND NORTHERN COLORADO WITH A SFC LOW DEVELOPING AND MOVING ACROSS THE FAR SE PLAINS THROUGH THE OVERNIGHT...WITH LATEST NAM INDICATING COLD FRONT BACKDOORING ACROSS THE PALMER DVD AND I-25 CORRIDOR BY 12Z FRIDAY. MODELS KEEPING THE BEST LIFT AND MOISTURE ASSOCIATED WITH PASSING UPPER TROUGH NORTH AND EAST OF THE CWA...HOWEVER WITH WAA AND LIFT ALONG BOUNDARY SLIDING ACROSS THE PALMER DVD AND DEVELOPING LOW LEVEL JET ACROSS THE KANSAS BORDER...HAVE KEPT THE ISOLATED TO SCATTERED POPS ACROSS THE PLAINS WITH BEST COVERAGE ACROSS THE FAR SE PLAINS. NAM SOUNDINGS INDICATING ELEVATED CONVECTION AND WITH MU CAPES BETWEEN 500-1200 J/KG AND BULK SHEARS INCREASING TO BETWEEN 40 AND 50 KTS...COULD SEE A FEW STRONG TO MARGINALLY SEVERE STORMS ACROSS THE EASTERN PLAINS WITH LARGE HAIL AND GUSTY WINDS THE MAIN THREATS. -MW .LONG TERM... (FRIDAY THROUGH WEDNESDAY) ...MAIN CONCERN IS COOL AIR EARLY IN PERIOD THEN RETURN TO SOME MONSOON MOISTURE DURING THE MIDWEEK... AS MENTIONED ABOVE...LATEST 06Z NAM SIMULATION HAS COLD FRONT BACKDOORING INTO THE REGION BY 12Z FRIDAY. THIS FRONT SHOULD BE DOWN PAST THE CO/NM BORDER PRIOR TO NOON. THE MAIN CONCERN WITH THIS BOUNDARY WILL BE MUCH COOLER AIR MOVING INTO THE REGION. TEMPS ON FRIDAY WILL ONLY REACH INTO THE LOWER 70S MOST AREA...WITH SOME AREAS OVER THE PALMER DVD NOT GETTING OUT OF THE 50S. AS FOR PRECIP...THERE MAY BE SOME EXITING TSRA DURING THE 12-15 UTC TIME FRAME OVER THE FAR E PLAINS...BUT AFTER THESE MOVE OUT I BELIEVE THE CHANCES OF PRECIP ARE GOING TO BE RATHER QUITE LOW OVER THE AREA. THE BEST CHANCES OF PRECIP WILL BE OVER THE E SLOPES OF THE S MTNS DURING THE AFTERNOON TIME PDS. ANY TSRA THAT DO DEVELOP WILL QUICKLY WEAKEN AS THEY MOVE E ONTO THE MUCH COOLER AIR OVER THE ADJ PLAINS. FRIDAY WILL LIKELY BE MOSTLY CLOUDY TO CLOUDY OVER THE PLAINS ALL DAY...WITH THE BEST CHANCE OF OVC CONDITIONS OVER THE S MTNS/ADJ PLAINS. AS FOR AREAS W OF THE S MTNS...THESE AREAS SHOULD REMAIN MOSTLY CLEAR AND WARM. BY FRIDAY NIGHT THE CHANCES OF PRECIP WILL INCREASE OVER THE FAR SE SXNS OF THE SE CO PLAINS AS WAA DEVELOPS OVER THIS REGION. I EXPECT WE WILL SEE SOME ELEVATED CONVECTION BY LATE EVENING/EARLY MORNING HOURS AND THIS ACTIVITY WILL THEN MOVE SE INTO OK/KS. SOME OF THIS CONVECTION COULD BE STRONG (MAINLY HAIL). EXCEPT FOR THE SLIGHT CHANCE OF LINGERING MORNING SHOWERS/CLOUDS OVER THE FAR E PLAINS...SAT SHOULD BE A NICE DAY OVER THE REGION WITH TEMPS RETURNING TO THE 70S/80S ACROSS THE PLAINS. BY SUNDAY..WE WILL SEE ANOTHER WEAK COOL FRONT MOVE INTO THE REGION. BY SUNDAY EVE WE MAY SEE SOME LIGHT SHOWERS OVER THE AREA. WE MAY ALSO SEE THINGS CLOUD UP SUNDAY NIGHT/EARLY MONDAY OVER THE E PLAINS. RIDGING ALOFT MOVES OVER THE AREA FOR MONDAY AND EXPECT MOSTLY SUNNY CONDITIONS WITH ISOLD CONVECTION BY AFTERNOON OVER THE REGION. BY TUESDAY INTO WED...BOTH GFS AND EC GUIDANCE INDICATE MONSOON MSTR WILL BE ADVECTED UP FROM THE S BY A BROAD TROUGH MOVING IN FROM THE PACIFIC. THIS WILL ALLOW PRECIP CHANCES TO RETURN TO BOTH THE MTNS AND PLAINS DURING THESE TWO DAYS. SIMULATIONS ARE SHOWING WE WILL HAVE SOME BRISK FLOW ALOFT SO IF SUFFICIENT LLVL INSTABILITY IS IN PLACE...WE MAY BE DEALING WITH A ORGANIZED STORMS ON THESE DAYS. /HODANISH && .AVIATION... ISOLATED -TSRA POSSIBLE ACROSS THE EASTERN MTS AND PLAINS LATE THIS AFTERNOON WITH LOCAL MVFR CIGS POSSIBLE...OTHERWISE EXPECTING VFR CONDITIONS WITH BREEZY EAST TO SOUTHEAST WINDS OF 15 TO 25 MPH DEVELOPING THROUGH THE AFTERNOON WITH LOWERING SFC PRESSURES ALONG WITH EASTERN MTS AHEAD OF UPPER TROUGH MOVING INTO WESTERN WYOMING THIS AFTERNOON. ISOLATED TO SCATTERED -TSRA EXPECTED ACROSS THE EASTERN MTS AND PLAINS TONIGHT AS A SFC LOW DEVELOPS AND MOVES ACROSS THE FAR SE PLAINS THROUGH THE OVERNIGHT...WITH LATEST NAM INDICATING COLD FRONT AND DEVELOPING MVFR AND PATCHY IFR CIGS AND NORTHERLY WIND SHIFT ACROSS THE PALMER DVD AND I-25 CORRIDOR BETWEEN 06Z-12Z FRIDAY. -MW && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 23/34 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 330 AM EDT THU SEP 4 2008 .SYNOPSIS... THE 06 UTC REGIONAL SURFACE ANALYSIS SHOWED A 1000 MB LOW (THE REMNANTS OF GUSTAV) CENTERED OVER WESTERN ARKANSAS...AND A HIGH PRESSURE RIDGE OVER THE PIEDMONT. VAPOR IMAGERY AND UPPER AIR DATA SHOWED VERY DRY MID-UPPER TROPOSPHERIC AIR EAST OF THE APALACHICOLA/CHATTAHOOCHEE RIVER...ON THE EASTERN SIDE OF A RIDGE FROM SOUTHERN MS TO THE EASTERN GREAT LAKES. && .SHORT TERM... (TODAY THROUGH SATURDAY) THE 00 UTC MODEL RUNS FORECAST PLENTY OF WARM DRY AIR ALOFT...WHICH WILL TEND TO SUPPRESS DEEP MOIST CONVECTION. HOWEVER...THERE STILL MAY BE JUST ENOUGH DEEP MOISTURE WEST OF THE APALACHICOLA/CHATTAHOOCHEE RIVER TO SUPPORT ISOLATED SHOWERS AND THUNDERSTORMS THIS AFTERNOON...AS WAS THE CASE WEDNESDAY. TEMPERATURES WILL BE NEAR AVERAGE BUT THE RELATIVE HUMIDITY WILL NOT BE VERY HIGH. THE NUMERICAL GUIDANCE HAS CONTINUED TO SHIFT THE TRACK OF HANNA FARTHER EAST WITH EACH RUN...AND OUR CONFIDENCE IS HIGH THAT THERE WILL BE NO DIRECT IMPACT TO OUR AREA FRIDAY AS IT PASSES EAST OF JACKSONVILLE. HOWEVER...THE GFS...NAM...AND ECMWF DO FORECAST SOME HIGH LEVEL MOISTURE TO SWEEP OVER OUR AREA FROM HANNA ON FRIDAY...RESULTING IN A MODEST INCREASE IN CS OVER OUR EASTERN COUNTIES...AND A SLIGHT CHANCE OF RAIN. A WEAK MID TROPOSPHERIC TROUGH IS FORECAST TO DEVELOP ALONG THE U.S. EAST COAST...AND THIS WILL COMBINE WITH ENOUGH DEEP LAYER MOISTURE TO WARRANT AT LEAST CLIMATOLOGICAL VALUE POPS. .LONG TERM... (SATURDAY NIGHT-THURSDAY) SOME LINGERING SHOWERS AND STORMS ASSOCIATED WITH A WEAK COLD FRONT MAY CONTINUE INTO THE SATURDAY EVENING HOURS BEFORE TRENDING DOWN. SUNDAY INTO MONDAY...THE MODELS SHOW PLENTY OF MID TO UPPER DRY AIR FILLING IN ACROSS THE CWA FROM NW TO SE WITH LIGHT NORTHERLY WINDS BEHIND THE WEAK FRONT. MONDAY NIGHT THROUGH WEDNESDAY...HURRICANE IKE WILL BEGIN TO APPROACH THE BAHAMAS AS AN UPPER TROUGH SHIFTS EAST OVER THE EASTERN STATES. THE GFS HAS IKE RECURVING EAST OF THE BAHAMAS AND THE ECMWF KEEPS IKE ON A GENERAL WESTWARD TRACK AND BEGINS TO RECURVE SOMEWHERE BETWEEN SOUTH FLORIDA AND THE BAHAMAS. THROUGH THIS PERIOD...FAIRLY BENIGN CONDITIONS WILL CONTINUE ACROSS THE CWA WITH ISOLATED TO WIDELY SCATTERED SHOWERS AND STORMS POSSIBLE EACH AFTERNOON. TEMPERATURES WILL REMAIN NEAR CLIMATOLOGY THROUGH THE EXTENDED PERIOD. && .AVIATION... VFR CONDITIONS WILL PREVAIL THROUGH THE MAJORITY OF THE PERIOD. SIMILAR TO YESTERDAY AFTERNOON...THE BEST CHANCE FOR SHOWERS TODAY WILL BE ACROSS THE WESTERN HALF OF THE CWA BETWEEN AND AROUND THE KPFN AND KDHN TERMINALS. && .MARINE... THE LATEST SURFACE OBSERVATIONS SHOW THAT A NOCTURNAL SURGE HAS DEVELOPED...BUT NOT AS STRONG AS THE ONE LAST NIGHT. ONCE AGAIN THE RUC APPEARS TO HAVE THE BEST HANDLE ON THIS...AND FORECASTS THE WINDS TO DIMINISH DURING THE MORNING HOURS. OTHERWISE...WINDS AND SEAS WILL REMAIN WELL BELOW CAUTION LEVELS THROUGH THE WEEKEND. && .FIRE WEATHER... && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 91 68 88 70 90 / 10 10 20 20 30 PANAMA CITY 88 73 87 74 87 / 20 10 20 20 30 DOTHAN 90 69 89 71 89 / 20 20 20 20 30 ALBANY 91 68 89 70 90 / 0 10 20 20 30 VALDOSTA 90 67 88 68 90 / 0 10 20 20 30 CROSS CITY 92 68 87 68 89 / 10 10 20 20 30 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. GM...NONE. && $$ LONG TERM/AVIATION...GIBBS REST OF DISCUSSION...FOURNIER fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIAMI FL 142 AM EDT THU SEP 4 2008 .AVIATION... EXPECT WDLY SCT SHOWERS TO CONTINUE TO MOVE SW OVER EAST COAST THROUGH THE MORNING, HOWEVER, THEY WILL MOVE FAST AND SO WILL NOT HAVE SIGNIFICANT IMPACT ON TERMINALS OPERATION. WL INDICATE VCSH OVER ALL ERN TERMINALS, EXCEPT KTMB (SHWRS WILL DISSIPATE BEFORE GETTING THAT FAR INLAND), BUT MOSTLY VFR CONDITIONS IS EXPECTED. VFR CONDITIONS ARE ALSO EXPECTED FOR KAPF THROUGH 06Z FRI. SFC WINDS WL REMAIN NE INCREASING IN SPEED OVER ALL TERMINALS BY MID MORNING TO 10 TO 15 KTS. HIGHER GUSTS CAN BE EXPECTED OVER EAST COAST. WND DIRECTION SHOULD SHIFT TO NORTHWEST FRI NIGHT AS HANNA MOVES NW JUST EAST OF THE BAHAMAS. && .PREV DISCUSSION... /ISSUED 1011 PM EDT WED SEP 3 2008/ UPDATE...SFC ANALYSIS CURRENTLY REVEALS ATLANTIC HIGH ACROSS THE SE STRETCHING INTO THE FLORIDA PENINSULA. GIVEN HANNA FARTHER EAST TRACK THE PRESSURE GRADIENT ACROSS THE EAST COAST HAS RELAXED SOME MEANING SLIGHTLY LESS WINDS THAN PREVIOUSLY FORECAST. GIVEN SO WILL DOWNGRADE SCA FOR BISCAYNE BAY TO A SMALL CRAFT EXERCISE CAUTION. EVEN WHEN THE WIND SPEEDS ACROSS MUCH OF THE ATLANTIC WATERS AT THE PRESENT TIME IS BELOW SCA...THE WINDS HAVE BEEN BLOWING FROM THE NE FOR A FEW DAYS NOW WHICH MEANS WAVE HEIGHTS WILL REMAIN HIGH AND IF ANYTHING INCREASE SOME AS HANNA PASSES TO THE EAST NEXT COUPLE OF DAYS IN RESPONSE TO A SOME INCREASE IN THE WINDS. SO SCA WILL CONTINUE IN PLACE UNTIL HANNA PASSES THE AREA FOR THE ATLANTIC WATERS. ON THURSDAY AND THURSDAY NIGHT, AS HANNA PASSES BY, WINDS SHOULD INCREASE SOME ACROSS THE ATLANTIC WATERS AND TURN MORE FROM THE NORTH AND THEN NW BY FRIDAY. WITH THAT, SWELLS SHOULD COME DOWN INTO THE COASTAL WATERS FROM THE NORTH BUT NOT LONG PERIOD SWELLS. THE STORM WILL BE MOVING BY CLOSE AND FAST ENOUGH THAT THE MAIN COMPONENT OF THE WAVES WILL BE WIND WAVES. SWELLS PERIOD WILL ALSO BE TOO SHORT TO RESULT IN LARGE BREAKERS AT THE COASTS. REGARDLESS OF THIS, SURF SHOULD BE ROUGH ENOUGH PARTICULARLY ACROSS THE PALM BEACH COUNTY BEACHES AND MAY BE BROWARD TO RESULT IN MINOR BEACH EROSION AND CONTINUED HIGH RISK OF RIP CURRENTS. VERY MINOR FLOODING OF LOW LYING COASTAL AREAS WHERE ROADS ARE VERY CLOSE TO THE WATER IS ALSO POSSIBLE. BUT GIVEN CONDITIONS AT THIS TIME DO NOT RISE TO THE LEVEL OF A HIGH SURF ADVISORY, DECIDED TO PUT OUT A COASTAL FLOOD STATEMENT TO HANDLE THIS AT THIS TIME FOR COASTAL BROWARD AND PALM BEACH COUNTIES. I THINK THIS IS THE PRUDENT THING TO DO GIVEN CURRENT TRENDS. DESPITE THIS, CAUTION IS ADVISED AND A HIGH SURF ADVISORY COULD STILL BE NEEDED SOMETIME ON THURSDAY. PREV DISCUSSION... /ISSUED 804 PM EDT WED SEP 3 2008/ AVIATION...NORTHEASTERLY WINDS ARE EXPECTED TO CONTINUE THROUGH THE PERIOD, BUT BECOME MORE NORTH NORTHEASTERLY LATE ON THURSDAY AS HANNA MOVES TO NEAR THE NORTHEAST BAHAMAS. ALSO, WINDS WILL BECOME GUSTY DURING THURSDAY. A FEW SHOWERS WILL CONTINUE TO MOVE IN FROM THE ATLANTIC THROUGH THE PERIOD AS WELL, BUT OVERALL COVERAGE IS EXPECTED TO BE LOW UNTIL HANNA MOVES CLOSER TO THE NORTHEASTERN BAHAMAS. /TINGLER PREV DISCUSSION... /ISSUED 358 PM EDT WED SEP 3 2008/ DISCUSSION... CURRENT WATER VAPOR ANIMATION AND RUC MODEL OBJECTIVE ANALYSIS INDICATE THAT SOUTH FLORIDA REMAINS IN A DEEP-LAYERED EAST- NORTHEAST FLOW REGIME BETWEEN A WEAKENING MID-TROPOSPHERIC ANTICYCLONE SITUATED OVER THE CENTRAL APPALACHIANS AND TROPICAL STORM HANNA OVER THE FAR SOUTHEASTERN BAHAMAS. CONFLUENT FLOW IN THE MID-LEVELS BETWEEN THESE TWO FEATURES HAS RESULTED IN A BROAD AREA OF SUBSIDENCE AND DRY AIR THAT WILL CONTINUE TO SPREAD OVER THE REGION FROM THE NORTHEAST FOR AT LEAST THE NEXT 12-24 HOURS...AND SHOULD SEVERELY LIMIT THE PROSPECTS FOR WIDESPREAD RAINFALL...AS PWAT VALUE ON THE 12Z RAOB FROM KMFL DROPPED ABRUPTLY TO 1.54 INCHES. HOWEVER...DESPITE THESE FACTORS...WILL INCLUDE A 20 POP FOR THE EAST COAST/ATLANTIC WATERS OVERNIGHT...AS LOW-LEVEL THERMAL PROFILES OVER THE GULF STREAM WILL BE MORE FAVORABLE OVERNIGHT FOR THE DEVELOPMENT OF A FEW LOW-TOPPED SHOWERS. MODELS ARE IN FAIRLY GOOD AGREEMENT THROUGHOUT THE SHORT TERM...IN FORECASTING THE MID-LEVEL HIGH OVER THE APPALACHIANS TO GRADUALLY WEAKEN...AS THE REMNANTS OF GUSTAV BECOME SHEARED AND EJECTED NORTHEASTWARD AHEAD OF A STRONGER MID-LATITUDE TROUGH OVER THE NORTHERN PLAINS. GUIDANCE IS ALSO IN GOOD AGREEMENT ON LIFTING THE UPPER LOW OFF THE COAST OF NEW ENGLAND NORTHWARD...IN CONJUNCTION WITH STRENGTHENING OF SUBTROPICAL RIDGE AXIS OVER THE CENTRAL ATLANTIC. AS INDICATED BY OFFICIAL FORECAST FROM NHC... THIS WILL ALLOW FOR A NORTHWESTWARD ACCELERATION OF TROPICAL STORM HANNA THROUGH THE END OF THE WEEK. CLOUD COVER AND NORTH TO NORTHWEST WINDS WILL BE ON THE INCREASE FROM THURSDAY THROUGH EARLY FRIDAY...AS HANNA MAKES HER CLOSEST APPROACH TO SOUTH FLORIDA. THE PRECIPITATION FORECAST REMAINS PROBLEMATIC...AS MOST OF THE STATISTICAL GUIDANCE INDICATES THAT BULK OF THE PRECIPITATION WILL REMAIN OFFSHORE AND OVER THE LOCAL ATLANTIC WATERS. HOWEVER...DUE TO REMAINING UNCERTAINTY AT THIS TIME RANGE...AND THE POTENTIAL FOR AT LEAST A FEW OUTER RAIN BANDS TO BE PIVOTING SOUTHEASTWARD ACROSS THE AREA...WILL MAINTAIN LOW CHANCE POPS FOR THE NORTHEAST QUADRANT OF THE FORECAST AREA...SLIGHT CHANCE SOUTHEAST...AND HIGHEST CHANCES OVER THE ATLANTIC WATERS. A WIND ADVISORY WILL LIKELY BE REQUIRED FOR THE COASTAL ZONES AND PORTIONS OF THE METROPOLITAN ZONES FROM THURSDAY AFTERNOON THROUGH FRIDAY MORNING. THERE WILL ALSO LIKELY BE A SIGNIFICANT IMPACT FROM HIGH SURF/BEACH EROSION...AND POSSIBLE COASTAL FLOODING... MAINLY FOR PORTIONS OF PALM BEACH COUNTY. CONDITIONS WILL IMPROVE FROM SOUTH TO NORTH DURING THE DAY ON FRIDAY AND INTO FRIDAY NIGHT. WILL STICK CLOSE TO A BLEND OF FWC/MAV/MET TEMPERATURES THROUGH THE PERIOD...BUT WILL CONTINUE TREND OF HOTTER TEMPERATURES ON FRIDAY AFTERNOON ALONG THE EAST COAST...GIVEN ANTICIPATION OF MODERATE SOUTHWEST FLOW AND CLEARING SKIES. THE GLOBAL MODELS ARE IN STRONG AGREEMENT ON BUILDING THE CENTRAL ATLANTIC SUBTROPICAL RIDGE AXIS OVER SOUTH FLORIDA FROM SATURDAY THROUGH THE BEGINNING OF NEXT WEEK...WHICH WILL ULTIMATELY RESULT IN A PERIOD OF BOTH PWATS AND POPS LOWER THAN CLIMO. TOWARD THE BEGINNING OF NEXT WEEK...THE WEATHER ACROSS SOUTH FLORIDA WILL DEPEND HEAVILY ON THE TRACK OF TROPICAL STORM IKE...WHICH IS FORECAST TO BE MOVING THROUGH THE BAHAMAS...BASED ON LATEST OFFICIAL TRACK FROM NHC. WILL MAKE NO CHANGES TO THIS PORTION OF THE FORECAST DUE TO UNCERTAINTIES AT THIS TIME. MARINE... PRIMARY AREA OF CONCERN IS WITH THE EFFECTS OF TROPICAL STORM HANNA ON THE LOCAL ATLANTIC WATERS. THE CURRENT FORECAST TRACK FROM NHC MAINTAINS HANNA ON A NORTHWESTWARD HEADING ACROSS THE BAHAMAS FROM THURSDAY INTO THE FIRST PART OF FRIDAY...AND EXPECT WINDS TO RESPOND BY INCREASING TO 20-25 KNOTS AND BACKING FROM NORTHEAST- NORTH-NORTHWEST THROUGH THE DAY ON THURSDAY. IF HANNA REMAINS ON TRACK...SOUTHWEST FLOW WILL SET IN BY FRIDAY. A STRONG NORTHERLY COMPONENT OVER THE GULF STREAM WILL ALLOW SEAS TO RAPIDLY BUILD...WITH PEAKS OF 14-16 FEET LIKELY TO OCCUR LATE ON THURSDAY. COMBINED SEAS WILL BE ENHANCED BY NORTHEAST ORIENTED SWELL GENERATED BY HANNA...BUT HAVE TRIMMED BACK VALUES OF SWELL HEIGHT SLIGHTLY BASED ON A FORECAST TRACK A BIT FURTHER TO THE EAST. EXPECT CONDITIONS TO IMPROVE FROM FRIDAY NIGHT INTO SATURDAY...BUT DID EXTEND SCA THROUGH 12Z FRIDAY FOR THE ATLANTIC WATERS AND BISCAYNE BAY. A VERY HIGH RISK OF RIP CURRENTS WILL CONTINUE AT ALL ATLANTIC COAST BEACHES UNTIL LATE THIS WEEKEND OR EARLY NEXT WEEK...AND SWIMMING IS STRONGLY DISCOURAGED. FIRE WEATHER... DRY AIR IN SUBSIDENT REGIME ALONG SOUTHWESTERN FLANK OF TROPICAL STORM HANNA WILL FORCE MINIMUM AFTERNOON RH VALUES INTO THE 45-50 PERCENT RANGE ON THURSDAY/FRIDAY AFTERNOONS...ALONG WITH WINDY CONDITIONS REGION-WIDE. HOWEVER...NO FIRE WEATHER PROBLEMS ARE ANTICIPATED AT THIS TIME. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 89 74 90 73 / 20 30 30 10 FORT LAUDERDALE 91 76 93 76 / 20 20 20 10 MIAMI 90 76 93 76 / 20 10 10 10 NAPLES 92 73 89 73 / - - - 10 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...SMALL CRAFT ADVISORY UNTIL 8 AM EDT FRIDAY FOR AMZ650-AMZ651- AMZ670-AMZ671. GM...NONE. && $$ LONG TERM...54/BNB SHORT TERM/AVIATION...47/RHG fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIAMI FL 1011 PM EDT WED SEP 3 2008 .UPDATE...SFC ANALYSIS CURRENTLY REVEALS ATLANTIC HIGH ACROSS THE SE STRETCHING INTO THE FLORIDA PENINSULA. GIVEN HANNA FARTHER EAST TRACK THE PRESSURE GRADIENT ACROSS THE EAST COAST HAS RELAXED SOME MEANING SLIGHTLY LESS WINDS THAN PREVIOUSLY FORECAST. GIVEN SO WILL DOWNGRADE SCA FOR BISCAYNE BAY TO A SMALL CRAFT EXERCISE CAUTION. EVEN WHEN THE WIND SPEEDS ACROSS MUCH OF THE ATLANTIC WATERS AT THE PRESENT TIME IS BELOW SCA...THE WINDS HAVE BEEN BLOWING FROM THE NE FOR A FEW DAYS NOW WHICH MEANS WAVE HEIGHTS WILL REMAIN HIGH AND IF ANYTHING INCREASE SOME AS HANNA PASSES TO THE EAST NEXT COUPLE OF DAYS IN RESPONSE TO A SOME INCREASE IN THE WINDS. SO SCA WILL CONTINUE IN PLACE UNTIL HANNA PASSES THE AREA FOR THE ATLANTIC WATERS. ON THURSDAY AND THURSDAY NIGHT, AS HANNA PASSES BY, WINDS SHOULD INCREASE SOME ACROSS THE ATLANTIC WATERS AND TURN MORE FROM THE NORTH AND THEN NW BY FRIDAY. WITH THAT, SWELLS SHOULD COME DOWN INTO THE COASTAL WATERS FROM THE NORTH BUT NOT LONG PERIOD SWELLS. THE STORM WILL BE MOVING BY CLOSE AND FAST ENOUGH THAT THE MAIN COMPONENT OF THE WAVES WILL BE WIND WAVES. SWELLS PERIOD WILL ALSO BE TOO SHORT TO RESULT IN LARGE BREAKERS AT THE COASTS. REGARDLESS OF THIS, SURF SHOULD BE ROUGH ENOUGH PARTICULARLY ACROSS THE PALM BEACH COUNTY BEACHES AND MAY BE BROWARD TO RESULT IN MINOR BEACH EROSION AND CONTINUED HIGH RISK OF RIP CURRENTS. VERY MINOR FLOODING OF LOW LYING COASTAL AREAS WHERE ROADS ARE VERY CLOSE TO THE WATER IS ALSO POSSIBLE. BUT GIVEN CONDITIONS AT THIS TIME DO NOT RISE TO THE LEVEL OF A HIGH SURF ADVISORY, DECIDED TO PUT OUT A COASTAL FLOOD STATEMENT TO HANDLE THIS AT THIS TIME FOR COASTAL BROWARD AND PALM BEACH COUNTIES. I THINK THIS IS THE PRUDENT THING TO DO GIVEN CURRENT TRENDS. DESPITE THIS, CAUTION IS ADVISED AND A HIGH SURF ADVISORY COULD STILL BE NEEDED SOMETIME ON THURSDAY. && .PREV DISCUSSION... /ISSUED 804 PM EDT WED SEP 3 2008/ AVIATION...NORTHEASTERLY WINDS ARE EXPECTED TO CONTINUE THROUGH THE PERIOD, BUT BECOME MORE NORTH NORTHEASTERLY LATE ON THURSDAY AS HANNA MOVES TO NEAR THE NORTHEAST BAHAMAS. ALSO, WINDS WILL BECOME GUSTY DURING THURSDAY. A FEW SHOWERS WILL CONTINUE TO MOVE IN FROM THE ATLANTIC THROUGH THE PERIOD AS WELL, BUT OVERALL COVERAGE IS EXPECTED TO BE LOW UNTIL HANNA MOVES CLOSER TO THE NORTHEASTERN BAHAMAS. /TINGLER PREV DISCUSSION... /ISSUED 358 PM EDT WED SEP 3 2008/ DISCUSSION... CURRENT WATER VAPOR ANIMATION AND RUC MODEL OBJECTIVE ANALYSIS INDICATE THAT SOUTH FLORIDA REMAINS IN A DEEP-LAYERED EAST- NORTHEAST FLOW REGIME BETWEEN A WEAKENING MID-TROPOSPHERIC ANTICYCLONE SITUATED OVER THE CENTRAL APPALACHIANS AND TROPICAL STORM HANNA OVER THE FAR SOUTHEASTERN BAHAMAS. CONFLUENT FLOW IN THE MID-LEVELS BETWEEN THESE TWO FEATURES HAS RESULTED IN A BROAD AREA OF SUBSIDENCE AND DRY AIR THAT WILL CONTINUE TO SPREAD OVER THE REGION FROM THE NORTHEAST FOR AT LEAST THE NEXT 12-24 HOURS...AND SHOULD SEVERELY LIMIT THE PROSPECTS FOR WIDESPREAD RAINFALL...AS PWAT VALUE ON THE 12Z RAOB FROM KMFL DROPPED ABRUPTLY TO 1.54 INCHES. HOWEVER...DESPITE THESE FACTORS...WILL INCLUDE A 20 POP FOR THE EAST COAST/ATLANTIC WATERS OVERNIGHT...AS LOW-LEVEL THERMAL PROFILES OVER THE GULF STREAM WILL BE MORE FAVORABLE OVERNIGHT FOR THE DEVELOPMENT OF A FEW LOW-TOPPED SHOWERS. MODELS ARE IN FAIRLY GOOD AGREEMENT THROUGHOUT THE SHORT TERM...IN FORECASTING THE MID-LEVEL HIGH OVER THE APPALACHIANS TO GRADUALLY WEAKEN...AS THE REMNANTS OF GUSTAV BECOME SHEARED AND EJECTED NORTHEASTWARD AHEAD OF A STRONGER MID-LATITUDE TROUGH OVER THE NORTHERN PLAINS. GUIDANCE IS ALSO IN GOOD AGREEMENT ON LIFTING THE UPPER LOW OFF THE COAST OF NEW ENGLAND NORTHWARD...IN CONJUNCTION WITH STRENGTHENING OF SUBTROPICAL RIDGE AXIS OVER THE CENTRAL ATLANTIC. AS INDICATED BY OFFICIAL FORECAST FROM NHC... THIS WILL ALLOW FOR A NORTHWESTWARD ACCELERATION OF TROPICAL STORM HANNA THROUGH THE END OF THE WEEK. CLOUD COVER AND NORTH TO NORTHWEST WINDS WILL BE ON THE INCREASE FROM THURSDAY THROUGH EARLY FRIDAY...AS HANNA MAKES HER CLOSEST APPROACH TO SOUTH FLORIDA. THE PRECIPITATION FORECAST REMAINS PROBLEMATIC...AS MOST OF THE STATISTICAL GUIDANCE INDICATES THAT BULK OF THE PRECIPITATION WILL REMAIN OFFSHORE AND OVER THE LOCAL ATLANTIC WATERS. HOWEVER...DUE TO REMAINING UNCERTAINTY AT THIS TIME RANGE...AND THE POTENTIAL FOR AT LEAST A FEW OUTER RAIN BANDS TO BE PIVOTING SOUTHEASTWARD ACROSS THE AREA...WILL MAINTAIN LOW CHANCE POPS FOR THE NORTHEAST QUADRANT OF THE FORECAST AREA...SLIGHT CHANCE SOUTHEAST...AND HIGHEST CHANCES OVER THE ATLANTIC WATERS. A WIND ADVISORY WILL LIKELY BE REQUIRED FOR THE COASTAL ZONES AND PORTIONS OF THE METROPOLITAN ZONES FROM THURSDAY AFTERNOON THROUGH FRIDAY MORNING. THERE WILL ALSO LIKELY BE A SIGNIFICANT IMPACT FROM HIGH SURF/BEACH EROSION...AND POSSIBLE COASTAL FLOODING... MAINLY FOR PORTIONS OF PALM BEACH COUNTY. CONDITIONS WILL IMPROVE FROM SOUTH TO NORTH DURING THE DAY ON FRIDAY AND INTO FRIDAY NIGHT. WILL STICK CLOSE TO A BLEND OF FWC/MAV/MET TEMPERATURES THROUGH THE PERIOD...BUT WILL CONTINUE TREND OF HOTTER TEMPERATURES ON FRIDAY AFTERNOON ALONG THE EAST COAST...GIVEN ANTICIPATION OF MODERATE SOUTHWEST FLOW AND CLEARING SKIES. THE GLOBAL MODELS ARE IN STRONG AGREEMENT ON BUILDING THE CENTRAL ATLANTIC SUBTROPICAL RIDGE AXIS OVER SOUTH FLORIDA FROM SATURDAY THROUGH THE BEGINNING OF NEXT WEEK...WHICH WILL ULTIMATELY RESULT IN A PERIOD OF BOTH PWATS AND POPS LOWER THAN CLIMO. TOWARD THE BEGINNING OF NEXT WEEK...THE WEATHER ACROSS SOUTH FLORIDA WILL DEPEND HEAVILY ON THE TRACK OF TROPICAL STORM IKE...WHICH IS FORECAST TO BE MOVING THROUGH THE BAHAMAS...BASED ON LATEST OFFICIAL TRACK FROM NHC. WILL MAKE NO CHANGES TO THIS PORTION OF THE FORECAST DUE TO UNCERTAINTIES AT THIS TIME. MARINE... PRIMARY AREA OF CONCERN IS WITH THE EFFECTS OF TROPICAL STORM HANNA ON THE LOCAL ATLANTIC WATERS. THE CURRENT FORECAST TRACK FROM NHC MAINTAINS HANNA ON A NORTHWESTWARD HEADING ACROSS THE BAHAMAS FROM THURSDAY INTO THE FIRST PART OF FRIDAY...AND EXPECT WINDS TO RESPOND BY INCREASING TO 20-25 KNOTS AND BACKING FROM NORTHEAST- NORTH-NORTHWEST THROUGH THE DAY ON THURSDAY. IF HANNA REMAINS ON TRACK...SOUTHWEST FLOW WILL SET IN BY FRIDAY. A STRONG NORTHERLY COMPONENT OVER THE GULF STREAM WILL ALLOW SEAS TO RAPIDLY BUILD...WITH PEAKS OF 14-16 FEET LIKELY TO OCCUR LATE ON THURSDAY. COMBINED SEAS WILL BE ENHANCED BY NORTHEAST ORIENTED SWELL GENERATED BY HANNA...BUT HAVE TRIMMED BACK VALUES OF SWELL HEIGHT SLIGHTLY BASED ON A FORECAST TRACK A BIT FURTHER TO THE EAST. EXPECT CONDITIONS TO IMPROVE FROM FRIDAY NIGHT INTO SATURDAY...BUT DID EXTEND SCA THROUGH 12Z FRIDAY FOR THE ATLANTIC WATERS AND BISCAYNE BAY. A VERY HIGH RISK OF RIP CURRENTS WILL CONTINUE AT ALL ATLANTIC COAST BEACHES UNTIL LATE THIS WEEKEND OR EARLY NEXT WEEK...AND SWIMMING IS STRONGLY DISCOURAGED. FIRE WEATHER... DRY AIR IN SUBSIDENT REGIME ALONG SOUTHWESTERN FLANK OF TROPICAL STORM HANNA WILL FORCE MINIMUM AFTERNOON RH VALUES INTO THE 45-50 PERCENT RANGE ON THURSDAY/FRIDAY AFTERNOONS...ALONG WITH WINDY CONDITIONS REGION-WIDE. HOWEVER...NO FIRE WEATHER PROBLEMS ARE ANTICIPATED AT THIS TIME. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 80 89 74 90 / 20 20 30 30 FORT LAUDERDALE 82 91 76 93 / 20 20 20 20 MIAMI 81 90 76 93 / 10 20 10 10 NAPLES 77 92 73 89 / 10 - - - && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...SMALL CRAFT ADVISORY UNTIL 8 AM EDT FRIDAY FOR AMZ650-AMZ651- AMZ670-AMZ671. GM...NONE. && $$ LONG TERM...52/PS SHORT TERM/AVIATION...04/AT fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIAMI FL 804 PM EDT WED SEP 3 2008 .AVIATION...NORTHEASTERLY WINDS ARE EXPECTED TO CONTINUE THROUGH THE PERIOD, BUT BECOME MORE NORTH NORTHEASTERLY LATE ON THURSDAY AS HANNA MOVES TO NEAR THE NORTHEAST BAHAMAS. ALSO, WINDS WILL BECOME GUSTY DURING THURSDAY. A FEW SHOWERS WILL CONTINUE TO MOVE IN FROM THE ATLANTIC THROUGH THE PERIOD AS WELL, BUT OVERALL COVERAGE IS EXPECTED TO BE LOW UNTIL HANNA MOVES CLOSER TO THE NORTHEASTERN BAHAMAS. /TINGLER && .PREV DISCUSSION... /ISSUED 358 PM EDT WED SEP 3 2008/ DISCUSSION... CURRENT WATER VAPOR ANIMATION AND RUC MODEL OBJECTIVE ANALYSIS INDICATE THAT SOUTH FLORIDA REMAINS IN A DEEP-LAYERED EAST- NORTHEAST FLOW REGIME BETWEEN A WEAKENING MID-TROPOSPHERIC ANTICYCLONE SITUATED OVER THE CENTRAL APPALACHIANS AND TROPICAL STORM HANNA OVER THE FAR SOUTHEASTERN BAHAMAS. CONFLUENT FLOW IN THE MID-LEVELS BETWEEN THESE TWO FEATURES HAS RESULTED IN A BROAD AREA OF SUBSIDENCE AND DRY AIR THAT WILL CONTINUE TO SPREAD OVER THE REGION FROM THE NORTHEAST FOR AT LEAST THE NEXT 12-24 HOURS...AND SHOULD SEVERELY LIMIT THE PROSPECTS FOR WIDESPREAD RAINFALL...AS PWAT VALUE ON THE 12Z RAOB FROM KMFL DROPPED ABRUPTLY TO 1.54 INCHES. HOWEVER...DESPITE THESE FACTORS...WILL INCLUDE A 20 POP FOR THE EAST COAST/ATLANTIC WATERS OVERNIGHT...AS LOW-LEVEL THERMAL PROFILES OVER THE GULF STREAM WILL BE MORE FAVORABLE OVERNIGHT FOR THE DEVELOPMENT OF A FEW LOW-TOPPED SHOWERS. MODELS ARE IN FAIRLY GOOD AGREEMENT THROUGHOUT THE SHORT TERM...IN FORECASTING THE MID-LEVEL HIGH OVER THE APPALACHIANS TO GRADUALLY WEAKEN...AS THE REMNANTS OF GUSTAV BECOME SHEARED AND EJECTED NORTHEASTWARD AHEAD OF A STRONGER MID-LATITUDE TROUGH OVER THE NORTHERN PLAINS. GUIDANCE IS ALSO IN GOOD AGREEMENT ON LIFTING THE UPPER LOW OFF THE COAST OF NEW ENGLAND NORTHWARD...IN CONJUNCTION WITH STRENGTHENING OF SUBTROPICAL RIDGE AXIS OVER THE CENTRAL ATLANTIC. AS INDICATED BY OFFICIAL FORECAST FROM NHC... THIS WILL ALLOW FOR A NORTHWESTWARD ACCELERATION OF TROPICAL STORM HANNA THROUGH THE END OF THE WEEK. CLOUD COVER AND NORTH TO NORTHWEST WINDS WILL BE ON THE INCREASE FROM THURSDAY THROUGH EARLY FRIDAY...AS HANNA MAKES HER CLOSEST APPROACH TO SOUTH FLORIDA. THE PRECIPITATION FORECAST REMAINS PROBLEMATIC...AS MOST OF THE STATISTICAL GUIDANCE INDICATES THAT BULK OF THE PRECIPITATION WILL REMAIN OFFSHORE AND OVER THE LOCAL ATLANTIC WATERS. HOWEVER...DUE TO REMAINING UNCERTAINTY AT THIS TIME RANGE...AND THE POTENTIAL FOR AT LEAST A FEW OUTER RAIN BANDS TO BE PIVOTING SOUTHEASTWARD ACROSS THE AREA...WILL MAINTAIN LOW CHANCE POPS FOR THE NORTHEAST QUADRANT OF THE FORECAST AREA...SLIGHT CHANCE SOUTHEAST...AND HIGHEST CHANCES OVER THE ATLANTIC WATERS. A WIND ADVISORY WILL LIKELY BE REQUIRED FOR THE COASTAL ZONES AND PORTIONS OF THE METROPOLITAN ZONES FROM THURSDAY AFTERNOON THROUGH FRIDAY MORNING. THERE WILL ALSO LIKELY BE A SIGNIFICANT IMPACT FROM HIGH SURF/BEACH EROSION...AND POSSIBLE COASTAL FLOODING... MAINLY FOR PORTIONS OF PALM BEACH COUNTY. CONDITIONS WILL IMPROVE FROM SOUTH TO NORTH DURING THE DAY ON FRIDAY AND INTO FRIDAY NIGHT. WILL STICK CLOSE TO A BLEND OF FWC/MAV/MET TEMPERATURES THROUGH THE PERIOD...BUT WILL CONTINUE TREND OF HOTTER TEMPERATURES ON FRIDAY AFTERNOON ALONG THE EAST COAST...GIVEN ANTICIPATION OF MODERATE SOUTHWEST FLOW AND CLEARING SKIES. THE GLOBAL MODELS ARE IN STRONG AGREEMENT ON BUILDING THE CENTRAL ATLANTIC SUBTROPICAL RIDGE AXIS OVER SOUTH FLORIDA FROM SATURDAY THROUGH THE BEGINNING OF NEXT WEEK...WHICH WILL ULTIMATELY RESULT IN A PERIOD OF BOTH PWATS AND POPS LOWER THAN CLIMO. TOWARD THE BEGINNING OF NEXT WEEK...THE WEATHER ACROSS SOUTH FLORIDA WILL DEPEND HEAVILY ON THE TRACK OF TROPICAL STORM IKE...WHICH IS FORECAST TO BE MOVING THROUGH THE BAHAMAS...BASED ON LATEST OFFICIAL TRACK FROM NHC. WILL MAKE NO CHANGES TO THIS PORTION OF THE FORECAST DUE TO UNCERTAINTIES AT THIS TIME. MARINE... PRIMARY AREA OF CONCERN IS WITH THE EFFECTS OF TROPICAL STORM HANNA ON THE LOCAL ATLANTIC WATERS. THE CURRENT FORECAST TRACK FROM NHC MAINTAINS HANNA ON A NORTHWESTWARD HEADING ACROSS THE BAHAMAS FROM THURSDAY INTO THE FIRST PART OF FRIDAY...AND EXPECT WINDS TO RESPOND BY INCREASING TO 20-25 KNOTS AND BACKING FROM NORTHEAST- NORTH-NORTHWEST THROUGH THE DAY ON THURSDAY. IF HANNA REMAINS ON TRACK...SOUTHWEST FLOW WILL SET IN BY FRIDAY. A STRONG NORTHERLY COMPONENT OVER THE GULF STREAM WILL ALLOW SEAS TO RAPIDLY BUILD...WITH PEAKS OF 14-16 FEET LIKELY TO OCCUR LATE ON THURSDAY. COMBINED SEAS WILL BE ENHANCED BY NORTHEAST ORIENTED SWELL GENERATED BY HANNA...BUT HAVE TRIMMED BACK VALUES OF SWELL HEIGHT SLIGHTLY BASED ON A FORECAST TRACK A BIT FURTHER TO THE EAST. EXPECT CONDITIONS TO IMPROVE FROM FRIDAY NIGHT INTO SATURDAY...BUT DID EXTEND SCA THROUGH 12Z FRIDAY FOR THE ATLANTIC WATERS AND BISCAYNE BAY. A VERY HIGH RISK OF RIP CURRENTS WILL CONTINUE AT ALL ATLANTIC COAST BEACHES UNTIL LATE THIS WEEKEND OR EARLY NEXT WEEK...AND SWIMMING IS STRONGLY DISCOURAGED. FIRE WEATHER... DRY AIR IN SUBSIDENT REGIME ALONG SOUTHWESTERN FLANK OF TROPICAL STORM HANNA WILL FORCE MINIMUM AFTERNOON RH VALUES INTO THE 45-50 PERCENT RANGE ON THURSDAY/FRIDAY AFTERNOONS...ALONG WITH WINDY CONDITIONS REGION-WIDE. HOWEVER...NO FIRE WEATHER PROBLEMS ARE ANTICIPATED AT THIS TIME. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 80 89 74 90 / 20 10 30 30 FORT LAUDERDALE 82 91 76 93 / 20 10 20 20 MIAMI 81 90 76 93 / 10 10 10 10 NAPLES 77 92 73 89 / 10 - - - && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...SMALL CRAFT ADVISORY UNTIL 8 AM EDT FRIDAY FOR AMZ630-AMZ650- AMZ651-AMZ670-AMZ671. GM...NONE. && $$ fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIAMI FL 358 PM EDT WED SEP 3 2008 .DISCUSSION... CURRENT WATER VAPOR ANIMATION AND RUC MODEL OBJECTIVE ANALYSIS INDICATE THAT SOUTH FLORIDA REMAINS IN A DEEP-LAYERED EAST- NORTHEAST FLOW REGIME BETWEEN A WEAKENING MID-TROPOSPHERIC ANTICYCLONE SITUATED OVER THE CENTRAL APPALACHIANS AND TROPICAL STORM HANNA OVER THE FAR SOUTHEASTERN BAHAMAS. CONFLUENT FLOW IN THE MID-LEVELS BETWEEN THESE TWO FEATURES HAS RESULTED IN A BROAD AREA OF SUBSIDENCE AND DRY AIR THAT WILL CONTINUE TO SPREAD OVER THE REGION FROM THE NORTHEAST FOR AT LEAST THE NEXT 12-24 HOURS...AND SHOULD SEVERELY LIMIT THE PROSPECTS FOR WIDESPREAD RAINFALL...AS PWAT VALUE ON THE 12Z RAOB FROM KMFL DROPPED ABRUPTLY TO 1.54 INCHES. HOWEVER...DESPITE THESE FACTORS...WILL INCLUDE A 20 POP FOR THE EAST COAST/ATLANTIC WATERS OVERNIGHT...AS LOW-LEVEL THERMAL PROFILES OVER THE GULF STREAM WILL BE MORE FAVORABLE OVERNIGHT FOR THE DEVELOPMENT OF A FEW LOW-TOPPED SHOWERS. MODELS ARE IN FAIRLY GOOD AGREEMENT THROUGHOUT THE SHORT TERM...IN FORECASTING THE MID-LEVEL HIGH OVER THE APPALACHIANS TO GRADUALLY WEAKEN...AS THE REMNANTS OF GUSTAV BECOME SHEARED AND EJECTED NORTHEASTWARD AHEAD OF A STRONGER MID-LATITUDE TROUGH OVER THE NORTHERN PLAINS. GUIDANCE IS ALSO IN GOOD AGREEMENT ON LIFTING THE UPPER LOW OFF THE COAST OF NEW ENGLAND NORTHWARD...IN CONJUNCTION WITH STRENGTHENING OF SUBTROPICAL RIDGE AXIS OVER THE CENTRAL ATLANTIC. AS INDICATED BY OFFICIAL FORECAST FROM NHC... THIS WILL ALLOW FOR A NORTHWESTWARD ACCELERATION OF TROPICAL STORM HANNA THROUGH THE END OF THE WEEK. CLOUD COVER AND NORTH TO NORTHWEST WINDS WILL BE ON THE INCREASE FROM THURSDAY THROUGH EARLY FRIDAY...AS HANNA MAKES HER CLOSEST APPROACH TO SOUTH FLORIDA. THE PRECIPITATION FORECAST REMAINS PROBLEMATIC...AS MOST OF THE STATISTICAL GUIDANCE INDICATES THAT BULK OF THE PRECIPITATION WILL REMAIN OFFSHORE AND OVER THE LOCAL ATLANTIC WATERS. HOWEVER...DUE TO REMAINING UNCERTAINTY AT THIS TIME RANGE...AND THE POTENTIAL FOR AT LEAST A FEW OUTER RAIN BANDS TO BE PIVOTING SOUTHEASTWARD ACROSS THE AREA...WILL MAINTAIN LOW CHANCE POPS FOR THE NORTHEAST QUADRANT OF THE FORECAST AREA...SLIGHT CHANCE SOUTHEAST...AND HIGHEST CHANCES OVER THE ATLANTIC WATERS. A WIND ADVISORY WILL LIKELY BE REQUIRED FOR THE COASTAL ZONES AND PORTIONS OF THE METROPOLITAN ZONES FROM THURSDAY AFTERNOON THROUGH FRIDAY MORNING. THERE WILL ALSO LIKELY BE A SIGNIFICANT IMPACT FROM HIGH SURF/BEACH EROSION...AND POSSIBLE COASTAL FLOODING... MAINLY FOR PORTIONS OF PALM BEACH COUNTY. CONDITIONS WILL IMPROVE FROM SOUTH TO NORTH DURING THE DAY ON FRIDAY AND INTO FRIDAY NIGHT. WILL STICK CLOSE TO A BLEND OF FWC/MAV/MET TEMPERATURES THROUGH THE PERIOD...BUT WILL CONTINUE TREND OF HOTTER TEMPERATURES ON FRIDAY AFTERNOON ALONG THE EAST COAST...GIVEN ANTICIPATION OF MODERATE SOUTHWEST FLOW AND CLEARING SKIES. THE GLOBAL MODELS ARE IN STRONG AGREEMENT ON BUILDING THE CENTRAL ATLANTIC SUBTROPICAL RIDGE AXIS OVER SOUTH FLORIDA FROM SATURDAY THROUGH THE BEGINNING OF NEXT WEEK...WHICH WILL ULTIMATELY RESULT IN A PERIOD OF BOTH PWATS AND POPS LOWER THAN CLIMO. TOWARD THE BEGINNING OF NEXT WEEK...THE WEATHER ACROSS SOUTH FLORIDA WILL DEPEND HEAVILY ON THE TRACK OF TROPICAL STORM IKE...WHICH IS FORECAST TO BE MOVING THROUGH THE BAHAMAS...BASED ON LATEST OFFICIAL TRACK FROM NHC. WILL MAKE NO CHANGES TO THIS PORTION OF THE FORECAST DUE TO UNCERTAINTIES AT THIS TIME. && .MARINE... PRIMARY AREA OF CONCERN IS WITH THE EFFECTS OF TROPICAL STORM HANNA ON THE LOCAL ATLANTIC WATERS. THE CURRENT FORECAST TRACK FROM NHC MAINTAINS HANNA ON A NORTHWESTWARD HEADING ACROSS THE BAHAMAS FROM THURSDAY INTO THE FIRST PART OF FRIDAY...AND EXPECT WINDS TO RESPOND BY INCREASING TO 20-25 KNOTS AND BACKING FROM NORTHEAST- NORTH-NORTHWEST THROUGH THE DAY ON THURSDAY. IF HANNA REMAINS ON TRACK...SOUTHWEST FLOW WILL SET IN BY FRIDAY. A STRONG NORTHERLY COMPONENT OVER THE GULF STREAM WILL ALLOW SEAS TO RAPIDLY BUILD...WITH PEAKS OF 14-16 FEET LIKELY TO OCCUR LATE ON THURSDAY. COMBINED SEAS WILL BE ENHANCED BY NORTHEAST ORIENTED SWELL GENERATED BY HANNA...BUT HAVE TRIMMED BACK VALUES OF SWELL HEIGHT SLIGHTLY BASED ON A FORECAST TRACK A BIT FURTHER TO THE EAST. EXPECT CONDITIONS TO IMPROVE FROM FRIDAY NIGHT INTO SATURDAY...BUT DID EXTEND SCA THROUGH 12Z FRIDAY FOR THE ATLANTIC WATERS AND BISCAYNE BAY. A VERY HIGH RISK OF RIP CURRENTS WILL CONTINUE AT ALL ATLANTIC COAST BEACHES UNTIL LATE THIS WEEKEND OR EARLY NEXT WEEK...AND SWIMMING IS STRONGLY DISCOURAGED. && .FIRE WEATHER... DRY AIR IN SUBSIDENT REGIME ALONG SOUTHWESTERN FLANK OF TROPICAL STORM HANNA WILL FORCE MINIMUM AFTERNOON RH VALUES INTO THE 45-50 PERCENT RANGE ON THURSDAY/FRIDAY AFTERNOONS...ALONG WITH WINDY CONDITIONS REGION-WIDE. HOWEVER...NO FIRE WEATHER PROBLEMS ARE ANTICIPATED AT THIS TIME. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 80 89 74 90 / 20 10 30 30 FORT LAUDERDALE 82 91 76 93 / 20 10 20 20 MIAMI 81 90 76 93 / 10 10 10 10 NAPLES 77 92 73 89 / 10 - - - && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...SMALL CRAFT ADVISORY UNTIL 8 AM EDT FRIDAY FOR AMZ630-AMZ650- AMZ651-AMZ670-AMZ671. GM...NONE. && $$ LONG TERM...70/DD SHORT TERM/AVIATION...30/KOB fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 401 AM EDT WED SEP 3 2008 .SYNOPSIS... THE 06 UTC REGIONAL SURFACE ANALYSIS SHOWED A 998 MB LOW CENTER (THE REMNANTS OF GUSTAV) NEAR TEXARKANA. A HIGH PRESSURE RIDGE OVER THE CAROLINAS WAS PROVIDING OUR AREA WITH EAST WINDS. AN INCREASE IN THE PRESSURE GRADIENT OVER THE NORTHEAST GULF HAS CAUSED AN UNEXPECTED SURGE IN THE EAST WINDS OVER OUR GULF COASTAL WATERS...SO SMALL CRAFT OPERATORS SHOULD EXERCISE CAUTION. VAPOR IMAGERY AND UPPER AIR DATA SHOWED A RIDGE AXIS FROM JUST NORTH OF THE REMNANTS OF GUSTAV TO HUDSON BAY...AND TROUGHS ON EITHER SIDE. ALTHOUGH CS CONTINUES TO STREAM OVER OUR AREA FROM THE NORTHWEST...UPSTREAM RAOBS (JACKSONVILLE FL) AND GOES SOUNDER IMAGERY SHOWED AN AREA OF DRY SINKING AIR IN THE MID TROPOSPHERE (UNDERNEATH THE CS OUTFLOW FROM GUSTAV) APPROACHING OUR AREA FROM THE NORTHEAST. && .SHORT TERM... (TODAY THROUGH FRIDAY) STRONG DRYING/WARMING IN THE MID TROPOSPHERE TODAY AND THURSDAY WILL SUPPRESS DEEP MOIST CONVECTION. A BLEND OF THE STATISTICAL OUTPUT AND RAW QPF FROM THE MODELS SHOW VERY LITTLE CHANCE OF RAIN OVER OUR AREA. THE BEST CHANCE FOR RAIN (THOUGH SLIGHT) WILL BE AROUND CROSS CITY THIS AFTERNOON WHERE THE BEST SEA BREEZE CONVERGENCE WILL OCCUR (AS THE NORTH FL SEA BREEZE BUMPS UP AGAINST THE OPPOSING 1000-700 MB EAST WINDS OF 5 TO 10 KT). ANY SHOWERS THAT DEVELOP WILL LIKELY BE SHORT-LIVED AND UNABLE TO REACH THE ICE GROWTH ZONE FOR LIGHTNING DEVELOPMENT. TEMPERATURES WILL BE NEAR AVERAGE...BUT SLIGHTLY LOWER RELATIVE HUMIDITY WILL MAKE IT FEEL A LITTLE MORE BEARABLE THAN THE DURING THE DOG DAYS OF SUMMER. THERE APPEARS TO BE A GROWING CONSENSUS AMONG THE NUMERICAL GUIDANCE IN TAKING HANNA FAR ENOUGH EAST OFF THE FL PENINSULA SO AS TO HAVE NO DIRECT IMPACT ON OUR WEATHER FRIDAY. TO BE ON THE SAFE SIDE WE WILL THROW IN SOME CLOUDS...SLIGHTLY COOLER TEMPERATURES...LOW-END RAIN CHANCES...AND SLIGHTLY HIGHER WINDS FOR OUR EASTERN ZONES FRIDAY. HOWEVER...DEPENDING ON THE STRUCTURE AND SIZE OF HANNA...IT MAY END UP BEING A WARM AND MOSTLY SUNNY DAY THERE AS WELL. .LONG TERM... (FRIDAY NIGHT THROUGH THURSDAY) THE TRACK GUIDANCE/OFFICIAL FORECAST SHOW HANNA MAKING LANDFALL FRIDAY EVENING NEAR THE SOUTH CAROLINA/GEORGIA STATE LINE. THIS TRACK WILL KEEP SLIGHTLY HIGHER POPS ACROSS THE FAR EASTERN ZONES FRIDAY EVENING AND INTO THE OVERNIGHT HOURS. ANY DEVIATION TO THE LEFT OR RIGHT OF THIS FORECAST TRACK WILL EITHER INCREASE OR DECREASE THESE CHANCES. THE ECMWF/NAM BOTH ARE THE TWO LEFT OUTLIERS. THE ECMWF SHOWS PLENTY OF DEEP LAYER MOISTURE AND A TIGHTER PRESSURE GRADIENT OVER THE EASTERN HALF OF THE CWA WITH HANNA CENTERED OVER THE FL/GA STATE LINE GOING INTO FRIDAY NIGHT. ON SATURDAY...HANNA WILL QUICKLY LIFT OUT TOWARD THE NE AS AN UPPER TROUGH AND COLD FRONT MOVE THROUGH THE EASTERN STATES. THE CPS (CYCLONE PHASE SPACE) DIAGRAMS SHOW HANNA BEGINNING EXTRATROPICAL TRANSITION (XT) AROUND THIS TIME AND AS A DEEP COLD CORE SYSTEM COME EARLY NEXT WEEK. SUNDAY INTO MONDAY...THE UPPER RIDGE WILL BUILD BACK OVER THE REGION. AT THE SURFACE...A TROUGH OR THE TAIL END OF THE PREVIOUSLY MENTIONED FRONT WILL STALL OVER THE CWA AND DISSIPATE INTO THE START OF THE WEEK. TUESDAY INTO THURSDAY...ALL EYES WILL REMAIN ON THE TROPICS. THE LATEST TRACK GUIDANCE SHOWS IKE APPROACHING THE BAHAMAS MONDAY NIGHT INTO TUESDAY. BEYOND THIS TIME FRAME...THE MODELS BEGIN TO SHOW QUITE LARGE DEVIATIONS. && .AVIATION... VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD AS A DRY AIRMASS REMAINS IN PLACE ACROSS THE REGION. LIGHT EASTERLY WINDS SOUTH OF THE RIDGE AXIS WILL CONTINUE THROUGH THE TAF PERIOD. SCATTERED TO BROKEN CIRRUS WILL CONTINUE TO STREAM OVER THE AREA THROUGH MUCH OF THE 24 HR PERIOD. && .MARINE... THE LATEST RUC IS THE ONLY MODEL WITH A GOOD HANDLE ON THE NOCTURNAL WIND SURGE OVER OUR COASTAL WATERS EARLY THIS MORNING...AND IT FORECASTS WINDS AND SEAS TO SLOWLY SUBSIDE AFTER DAYBREAK. SOME OF THE NUMERICAL GUIDANCE HINTS AT ANOTHER WIND SURGE LATE TONIGHT...SO WE WILL PLAY THE PERSISTENCE GAME AND FORECAST CAUTION LEVELS IN OUR COASTAL WATERS AGAIN LATE TONIGHT. OTHERWISE WINDS AND SEAS WILL REMAIN BELOW CAUTION LEVELS...AND HANNA WILL HAVE LITTLE IF ANY IMPACT ON OUR MARINE AREA. && .FIRE WEATHER... DRIER AIR IS FORECAST TO MIX DOWN TO THE SURFACE TODAY...AND REMAIN THROUGH AT LEAST THURSDAY. WE WENT ON THE DRIER SIDE OF GUIDANCE...BUT STILL DO NOT EXPECT RED FLAG CRITERIA. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 91 69 91 69 88 / 0 10 0 10 20 PANAMA CITY 89 73 88 72 88 / 10 10 10 0 10 DOTHAN 90 69 89 68 89 / 10 10 10 0 10 ALBANY 90 67 90 68 90 / 0 10 0 0 20 VALDOSTA 90 67 90 69 85 / 10 10 0 10 30 CROSS CITY 91 69 91 69 86 / 20 10 0 10 30 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. GM...NONE. && $$ FOURNIER/GIBBS/GIBBS fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 420 PM EDT THU SEP 4 2008 .SHORT TERM... TODAY THROUGH FRIDAY REMNANTS OF GUSTAV WILL CONTINUE TO PROVIDE THE FOCUS FOR RAIN AND TS CHANCES THROUGH TONIGHT. REMNANT UPPER VORT MAX WILL CONTINUE TO MERGE WITH A BROAD UPPER TROUGH OVER THE NORTHERN PLAINS AND QUICKLY ACCELERATE TO THE NE INTO THE EASTERN GREAT LAKES BY MORNING. TRAILING COLD FRONT WILL PUSH THROUGH THE REGION OVERNIGHT AND PROVIDE RATHER ROBUST LIFT. MODEL PROGS CONTINUE TO SUPPORT RATHER IMPRESSIVE MOMENTUM FIELDS...WHICH ARE CONFIRMED THUS FAR BY PROFILER AND SCATTEROMETER WINDS. IMPRESSIVE 50 TO 60 KNOT H85 WINDS WILL DEVELOP OVERNIGHT IN RESPONSE TO NOCTURNAL BIAS AND SHARP TEMPERATURES GRADIENT OFFERED BY THIS SYSTEM. WITH 45 TO 50 KNOTS STILL PROGGED AT H92...STILL CONCERNED WITH AN ISOLATED DAMAGING WIND THREAT ALONG A NARROW CORRIDOR...EMBEDDED IN A PREFRONTAL TROUGH. AMPLE LARGE SCALE ASCENT WILL BE IN PLACE TONIGHT WITH STRONG FRONTAL FORCING. THIS SYSTEM DEFINITELY RESEMBLES A DYNAMIC PATTERN SETUP WHERE A SQUALL LINE WOULD BE EXPECTED. DYNAMICS WITH SYSTEM ARE VERY AKIN TO A WINTER THIN LINE CONVECTIVE EVENT. ALTHOUGH...MUCH MORE LL MOISTURE IS AVAILABLE WHICH WOULD HELP ACCENTUATE PRECIP LOADING. ONE MAJOR DIFFERENCE WITH THIS SYSTEM IS THE LACK OF A STRONG RAPIDLY DEEPENING SFC LOW...WHICH MOST LIKELY WOULD BE THE MISSING LINK IN SUPPORTING MOMENTUM TRANSFER TO THE SFC. THE IS ALSO SOME CONCERN ON THE AMOUNT OF CAPE AVAILABLE GIVEN WARMING TEMPS ALOFT AND POOR SFC DESTABILIZATION. HOWEVER...STRONG DYNAMICS COULD OUTWEIGH POOR CAPE EFFECTS. HAVE FOLLOWED CLOSE TO THE NAM 12...AS IT HAS INITIALIZED WELL AND CONTINUES TO FOLLOW CLOSE TO SFC OBS. ISENTROPIC LIFT AT 310K LINES UP WELL WITH ONGOING PRECIP BANDS AND SO HAVE FOLLOWED THIS FEATURE INTO THE EVENING. BETTER FORCING DEVELOPS AND PUSHES INTO THE REGION LATE THIS EVENING AS COLD FRONT SWINGS INTO THE AREA. AS MENTIONED ABOVE...STRONG DYNAMICS IN PLACE...50 KNOT H5 SPEED MAX/H85 JET MAX OF 50 TO 60 KNOTS...WILL LIKELY SUPPORT A CONVECTIVE LINE. WARMING ALOFT AND NEAR TROPICAL ENVIRONMENT WILL LIKELY PRECLUDE LIGHTNING TO ONLY THE MOST VIGOROUS CELLS. UNIDIRECTIONAL DEEP MIXED FAST FLOW WILL SUPPORT A WIND THREAT WITH CONVECTION...BUT GIVEN CURRENTLY EXPECTED ISOLATED NATURE OF GUSTY/DAMAGING WIND...HAVE LEFT OUT OF THE ZONES AT THIS TIME. THERE IS STILL SOME CONCERN ON WHETHER THE LL INVERSION WOULD BE ABLE TO COMPLETELY MIX OUT COINCIDENT WITH A CONVECTIVE LINE GIVEN POOR CAA AND BL FLOW...SOMETHING A RAPIDLY DEEPENING SFC LOW WOULD LIKELY SUPPORT. HEAVY RAINFALL WOULD BE LIKELY WITH HEAVIER CELLS WITH PW VALUES OVER 2 INCHES. GIVEN NAM THETA-E PROGS AND SFC PRESSURE FALLS...THE BEST CHANCE FOR CONVECTION WILL BE EAST OF A SBN TO GUS LINE. FRIDAY...PREVIOUS FORECAST ON TRACK. DRY NW FLOW WILL ALLOW LOW STRATUS TO EVENTUALLY MIX OUT BY AFTERNOON WITH SH THREAT ENDING FAR EAST. NW WINDS AREA EXPECTED TO CONTINUE AND SO HAVE EXTENDED THE SCA AND CFW INTO THE EVENING GIVEN FORECAST WAVE HEIGHTS. LOOK FOR PERSISTENT CLOUDS IN THE EAST AS HANNA ADVANCES INTO SC/VA. && .LONG TERM... ...SATURDAY THROUGH THURSDAY... BROAD MID LEVEL TROUGH WILL BE ACROSS THE AREA MUCH OF THE PERIOD WITH SMALLER SCALE SHORT WAVES PASSING THROUGH. TIMING AND PCPN CHANCES WITH THESE WAVES ARE THE FOCUS FOR THIS FORECAST. CONTINUED TO LEAN TOWARD ECMWF FOR FORECAST DETAILS. THIS IS IN GOOD AGREEMENT WITH CURRENT FORECAST GRIDS AND FEW CHANGES NEEDED TO OVERALL FORECAST. SOME UNCERTAINTY CONTINUES BETWEEN MODELS WITH TIMING OF WAVE FOR LATTER HALF OF WEEKEND. INCREASING MID LEVEL MOISTURE BUT LIMITED DEPTH OF MOISTURE SHOULD KEEP BEST PCPN CHANCES CONFINED TO SUNDAY NIGHT INTO MONDAY NEAR ACTUAL SURFACE FRONTAL BOUNDARY. THIS FRONT BECOMES RATHER WEAK AND DIFFUSE SO CONFIDENCE LOW IN OVERALL WIDESPREAD NATURE OF PCPN. CONTINUED WITH LOW CHANCE POPS MONDAY AND MONDAY NIGHT. HIGH PRESSURE RETURNS TUESDAY INTO WEDNESDAY WITH SEASONABLE TEMPERATURES. APPROACH OF ANOTHER SHORT WAVE AND SURFACE FRONT EXPECTED TOWARD THURSDAY AS DEPICTED BY ECMWF. FOLLOWED HPC LEAD AND NEIGHBORING OFFICES WITH LOW CHANCE POPS BUT MEDIUM RANGE MODELS SEEM TO BE BULLISH WITH STRENGTH OF WAVES IN THESE LATER PERIODS AND TREND WEAKER WITH TIME. && .AVIATION... GUSTAV REMNANTS WILL CONTINUE TO BRING DETRIMENTAL AVIATION CONDITIONS TO A LARGE PORTION OF THE FA...ESPECIALLY IN THE WEST. LARGE AREA OF IFR TO LIFR CIGS ARE IN PLACE TO THE WEST OF THE FA UNDER A LARGE STRATIFORM RAIN SHIELD. THIS RAIN SHIELD IS EXPECTED TO CLIP THE WESTERN PORTION OF THE FA BRINGING THE AFOREMENTIONED FLIGHT CONDITIONS TO THE WEST. HAVE TAILORED THIS TO SBN TAF...IN LINE WITH MOS AND RUC13 PROGS. AREAS OF REDUCED STRATUS AND VISIBILITY WILL IMPROVE FOR A PERIOD OVER THE SE HALF OF THE FA AS A WARM FRONT LIFTS NORTH. EXPECTING SCT SHOWER ACTIVITY MAINLY IN THE SOUTHEASTERN HALF OF THE FA WITH BRIEF REDUCTIONS IN VISIBILITY. COLD FRONT IS EXPECTED TO PASS THROUGH THE FA OVERNIGHT WITH THE POTENTIAL FOR BRIEF HEAVY RAINFALL AND POSSIBLY EMBEDDED TS ALONG A SQUALL LINE. LARGE REDUCTIONS IN VISIBILITY ARE POSSIBLE WITH THIS BAND OF SH...WITH 1 MILE OR LESS POSSIBLE. HAVE WENT WITH A CB MENTION AT FWA AND SBN...BUT EXPECTING BEST CHANCE FOR THUNDER AND RESTRICTIONS TO BE AT FWA AND EAST...THIS INCLUDES LOWER VISIBILITY. WILL LEAVE THIS OUT OF TAFS UNTIL BETTER TIMING AND TRACK ARE ASCERTAINED. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT FRIDAY FOR LMZ043-046. && $$ SHORT TERM...CHAMBERLAIN LONG TERM...LASHLEY AVIATION...CHAMBERLAIN in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 203 PM EDT THU SEP 4 2008 .AVIATION... GUSTAV REMNANTS WILL CONTINUE TO BRING DETRIMENTAL AVIATION CONDITIONS TO A LARGE PORTION OF THE FA...ESPECIALLY IN THE WEST. LARGE AREA OF IFR TO LIFR CIGS ARE IN PLACE TO THE WEST OF THE FA UNDER A LARGE STRATIFORM RAIN SHIELD. THIS RAIN SHIELD IS EXPECTED TO CLIP THE WESTERN PORTION OF THE FA BRINGING THE AFOREMENTIONED FLIGHT CONDITIONS TO THE WEST. HAVE TAILORED THIS TO SBN TAF...IN LINE WITH MOS AND RUC13 PROGS. AREAS OF REDUCED STRATUS AND VISIBILITY WILL IMPROVE FOR A PERIOD OVER THE SE HALF OF THE FA AS A WARM FRONT LIFTS NORTH. EXPECTING SCT SHOWER ACTIVITY MAINLY IN THE SOUTHEASTERN HALF OF THE FA WITH BRIEF REDUCTIONS IN VISIBILITY. COLD FRONT IS EXPECTED TO PASS THROUGH THE FA OVERNIGHT WITH THE POTENTIAL FOR BRIEF HEAVY RAINFALL AND POSSIBLY EMBEDDED TS ALONG A SQUALL LINE. LARGE REDUCTIONS IN VISIBILITY ARE POSSIBLE WITH THIS BAND OF SH...WITH 1 MILE OR LESS POSSIBLE. HAVE WENT WITH A CB MENTION AT FWA AND SBN...BUT EXPECTING BEST CHANCE FOR THUNDER AND RESTRICTIONS TO BE AT FWA AND EAST...THIS INCLUDES LOWER VISIBILITY. WILL LEAVE THIS OUT OF TAFS UNTIL BETTER TIMING AND TRACK ARE ASCERTAINED. && .PREV DISCUSSION... /ISSUED 1241 PM EDT THU SEP 4 2008/ UPDATE... HAVE SENT AN UPDATE...RAISING POPS ACROSS THE BOARD ESPECIALLY IN THE WEST. GUSTAV REMNANTS CONTINUING TO SHIFT NE...TAKING A TRACK SLIGHTLY FARTHER EAST THAN FORECAST MODELS ORIGINALLY HAVE PROGGED. THIS WILL ALLOW PERSISTENT RAIN TO INFILTRATE PART OF THE FA THIS AFTERNOON MAINLY WEST OF A CASSOPOLIS TO LOGANSPORT LINE. FARTHER EAST...STRONG ISENTROPIC LIFT ALONG AN EAST WEST ORIENTED BAND...SUPPORTED BY INCREASED LL SOUTHERLY FLOW UNDER INCREASING LARGE SCALE LIFT...WILL SHIFT NORTH INTO THE FA SUPPORTING A SH/TS THREAT. BEST CHANCE FOR CONVECTION WILL BE IN THE FAR EAST WHERE SOLAR INSOLATION IS ONGOING AS TEMPS ARE CLIMBING INTO THE LOWER 80S. HAVE ADJUSTED HIGHS FOR TODAY...TRENDING HEAVILY TO THE 12Z NAM12. THIS MAINLY AFFECTS THE WEST WHERE HIGHS WERE CUT. EASTERN AREAS ARE STILL ON TRACK TO SEE MID TO UPPER 80S. PREV DISCUSSION... /ISSUED 645 AM EDT THU SEP 4 2008/ SHORT TERM... MANY SOURCES OF MODEL CONTENTION THIS PD MAKE FOR A DIFFICULT AND COMPLICATED FCST SCENARIO. REMNANT SFC LOW CNTR ASSOCD/W GUSTAV NOW BECOMING ABSORBED INTO FNTL SYS ASSOCD/W STG UPSTREAM SW TROUGH ACRS SD THIS MORNING AND BEGINNING TO ACCELERATE NEWD OUT OF AR WITH DOWNSTREAM PRES FALLS INTO NW IN SIGNALING RAPID BACKING OF THE LL FLW BEHIND YDA/S SHALLOW FNTL INTRUSION. HWVR COVERAGE OF SHOWERS/ISOLD THUNDER THIS MORNING QUITE POOR...CONFINED ACRS WRN IN...AND A FUNCTION OF AS YET FAIRLY WEAK ISENTROPIC ASCENT. DILEMMA THIS MORNING LIES W/TRACK OF SFC WAVE AND PLACEMENT OF OLD SFC BNDRY FM YDA. OF GREAT INTEREST IS POTENTIAL FOR TORNADOES THIS AFTN NR REMNANT SFC BNDRY ESP IN LIGHT OF SIG LL SHEAR THAT DVLPS WITHIN MOIST/LOW LCL ENVIRONMENT AND SLIGHTLY FASTER ARRIVAL OF SFC WAVE. CAVEAT OF COURSE LIES W/DEGREE OF DESTABILIZATION GIVEN DEEPENING MSTR PLUME AND CLD DEBRIS STREAMING NEWD NOT TO MENTION STRATUS THAT HAD DVLPD WITHIN INCREASING LL EASTERLIES THIS MORNING. HWVR SYNOPTIC PICTURE .AS WAS THE CASE YDA...CERTAINLY SUGGESTS A REAL POTENTIAL THIS AFTN/EARLY EVENING MAINLY ACRS NRN IN NORTHEAST OF SFC WAVE AND PERHAPS EXTENDING EWD INTO NW OH. WILL WORD THREAT ACCORDINGLY IN HWO LATER THIS MORNING. OTHERWISE MUCH NEEDED WIDESPREAD RAINFALL ON TAP FOR AT LEAST WRN/CNTRL PORTIONS GIVEN ALIGNING 00Z MODELS ON TRACK OF SFC WAVE THROUGH NW IN. DETAILS OF GFS/ECMWF CLOSE AND LARGELY BLENDED FOR GRIDDED DETAIL YET BOTH SEEM DEFICIENT TO SOME DEGREE W/FNTL RAINBAND LATE TONIGHT AS SEEN DOWN ACRS THE LWR MISSISSIPPI VALLEY THIS MORNING. AS SUCH WILL CARRY AT LEAST A LIKELY MENTION THROUGH NW OH LATE TONIGHT. IN ADDN...SOME RISK FOR DAMAGING WINDS THIS EVENING GIVEN INTENSE LLJ DVLPMNT ALG FNTL ZONE AND SOMETHING ELSE TO WATCH FOR. BY FRI AM...SYS ALREADY INTO SRN ONT W/SFC BNDRY WELL INTO OH. DOUBT MUCH NEED TO HOLD POPS OUTSIDE MORNING PD IF EVEN THAT BUT GIVEN HELTER SKELTER MODEL SOLUTIONS LAST FEW DAYS WILL STICK W/SOME MENTION YET AND IN ORDER TO FOSTER SOME CONSISTENCY AND COLLABORATION W/NEIGHBORING OFFICES. WILL THOUGH DROP AFTN MENTION EXCEPT ACRS NW OH. LONG TERM... SATURDAY THROUGH WEDNESDAY...THE LONG WAVE TROF WILL GRADUALLY DEEPEN OVER CENTRAL NORTH AMERICA AS A SERIES OF SHORT WAVES MOVES THROUGH THE FLOW. HAVE KEPT A CHANCE FOR STORMS MONDAY AND MONDAY NIGHT WITH THE ARRIVAL OF THE FIRST TROF. THE GFS AND THE ECMWF ARE IN REASONABLE AGREEMENT WITH THE TIMING OF THIS SYSTEM. TWEAKED RAIN CHANCES HIGHER GIVEN REASONABLE UPPER LEVEL SUPPORT AND LOW LEVEL FORCING ALONG THE FRONT. TEMPERATURES SHOULD FINALLY COOL BELOW NORMAL BY TUESDAY AS SOME COOL CANADIAN AIR SPREADS INTO THE AREA. THE NEXT SYSTEM SHOULD ARRIVE JUST AFTER THE END OF THE FORECAST PERIOD. KEPT WEDNESDAY DRY WITH TEMPERATURES RECOVERING TO NEAR NORMAL. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LMZ043-046. && $$ SHORT TERM...HOLSTEN LONG TERM...SKIPPER AVIATION...CHAMBERLAIN in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 1200 AM CDT WED SEP 3 2008 .DISCUSSION... HAVE RELEGATED POPS TO JUST S AND E OF DSM WITH EVENING UPDATE. RUC 305-310K ISENT SFCS KEEP BEST LIFT SE THIRD AND ESPECIALLY TOWARD KOTM. WEAKER LIFT BUT STILL PERIODS OF SATURATION FARTHER TO THE N AND W BUT DOES NOT APPEAR TO WARRANT MENTION AT THIS POINT. MODEL QPF CONTINUES TO HIGHLIGHT THESE AREAS...BUT HAVE BEEN OVERDONE RECENTLY AS WELL. SHORT TERM FORECASTS HAVE STARTED ADDING HEAVY RAIN WORDING FAR SE HOWEVER. WCD STAYS AROUND 13KFT OVERNIGHT WITH PWS AROUND 1.75 AND STORM MOTION NO MORE THAN 15KTS. && .PREV DISCUSSION... FALL LIKE COLD FRONT MOVING THROUGH CENTRAL IOWA THIS AFTERNOON AND MAY BE SWEEPING THE LAST OF THE 70 DEWPOINTS FROM THE STATE UNTIL NEXT SPRING. GOOD TEMPERATURE GRADIENT ACROSS THE STATE WITH CURRENT READINGS RANGING FROM THE UPPER 80S TO LOWER 90S OVER THE SOUTHEAST TO THE LOWER TO MID 60S TO THE NORTHWEST. BAND OF SHOWERS AND ISOLD THUNDERSTORMS OVER WESTERN IOWA THIS MORNING CONTINUES TO DIMINISH WITH RENEWED DEVELOPMENT OVER EASTERN IOWA AND NORTHERN MISSOURI DEVELOPING. SEVERE POTENTIAL QUITE LOW WITH EFFECTIVE SHEAR VALUES AROUND 20 KTS OR LESS...HIGH FREEZING LEVELS NEAR 15 KFT AND WEAK MID LEVEL LAPSE RATES. ATTENTION TURNS TO THE REMNANTS OF GUSTAV WHICH CURRENTLY REMAINS BLOCKED TO THE SOUTH AS ANOTHER LARGE HIGH PRESSURE SYSTEM MOVES EAST ACROSS THE UPPER MIDWEST. THE COOL HIGH PRESSURE WILL KEEP HIGHS UNSEASONABLY COOL ON WEDNESDAY WITH HIGHS IN THE 60S. GUSTAV WILL BEGIN TO LIFT TO THE NORTHEAST ON THURSDAY. WITH THE HIGH PRESSURE TO THE EAST AND HANNA APPROACHING FROM THE SOUTHEAST...GUSTAV SHOULD MOVE ACROSS EASTERN MISSOURI AND CENTRAL ILLINOIS WITH THE RAIN AXIS CLIPPING ACROSS THE SOUTHEAST THIRD OF IOWA. HIGH PRESSURE WILL KEEP REMAINDER OF THE AREA DRY THOUGH EXPANDING CLOUD SHIELD WILL LIMIT HIGH TEMPERATURES IN THE 60S ON THURSDAY. AREAS THAT HAVE PERSISTENT RAIN OVER THE SOUTHEAST MAY BE HELD IN THE 50S MUCH OF THE DAY. ANOTHER DISTURBANCES PASSES THROUGH FRIDAY NIGHT AND EARLY SATURDAY WITH BEST PRECIPITATION CHANCES OVER THE NORTHWEST. THIS SYSTEM WILL BRING ANOTHER PUSH OF FALL LIKE AIR TO THE STATE. A FINAL SYSTEM WILL APPROACH ON SUNDAY WITH PRECIPITATION CHANCES INCREASING FROM NORTHWEST TO SOUTHEAST. ANOTHER PUSH OF COLD AIR WILL FOLLOW AND LAST THROUGH MONDAY AND TUESDAY. HAVE GONE A CATEGORY OR TWO BELOW GUIDANCE TEMPS DURING THIS PERIOD WITH MEX AND MEN VALUES BIASED TOWARDS WARMER CLIMO. && .AVIATION...03/06Z COLD FRONT HAS PUSHED ALL THE WAY OUT OF IOWA. ALTHOUGH THE THREAT HAS NOT BEEN COMPLETELY ELIMINATED...THE MENTION OF PRECIP AND NON-VFR CIGS HAVE BEEN REMOVED FROM ALL SITES IN THE BODY OF TAF. PRECIP POTENTIAL ALONG AND JUST BEHIND THE FRONT SEEMS TO BE DIMINISHING SOMEWHAT...BUT THE NRN FRINGE OF GUSTAV REMNANTS WILL CONTINUE TO KEEP CHANCES GOING NEAR KOTM AND EVEN POSSIBLY KDSM THROUGH ENTIRE PERIOD. THERE SHOULD BE BREAKS HOWEVER...SO RATHER THAN TRYING TO TIME THEM OR HAVING A PROLONGED PERIOD HAVE STARTED WITH VCSH AT KOTM AND LEFT KDSM DRY. STRONGER BODY WORDING AND POSSIBLY THUNDER MAY NEED TO BE PLACED AT KOTM WITH LATER ISSUANCES AS TIMING CONFIDENCE INCREASES. CURRENT RADAR TRENDS TO NOT JUSTIFY ANYTHING MORE THAN VCSH. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. $$ LONG TERM...DONAVON SHORT TERM/AVIATION...FAB/BSS ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 148 PM EDT THU SEP 4 2008 .AVIATION... SURFACE LOW WHICH IS THE REMNANTS OF GUSTAV WILL MOVE NORTHEAST ACROSS THE FNT TAF SITE VICINITY BETWEEN 06 AND 12Z. IN THE MEANTIME A SURFACE WARM FRONT JUST SOUTH OF THE SOUTHERN MICHIGAN BORDER WILL LIFT RAPIDLY NORTH AFTER 03Z. MOST OF THE PRECIPITATION AND LOW LEVEL MOISTURE WILL BE ALONG AND NORTH OF THE SURFACE LOW TRACK. LOW LEVEL WIND FIELD WILL INCREASE RAPIDLY OVERNIGHT AS GRADIENT TIGHTENS ON THE SOUTH SIDE OF THE PASSING LOW. HAVE ADDED LOW LEVEL WIND SHEAR TO FNT/DET/DTW OVERNIGHT. THE TRAILING COLD FRONT WILL SWING THROUGH THE DET/DTW SITES BETWEEN 09 AND 12Z WITH PRECIPITATION AND SOME MVFR CONDITIONS. LOW LEVEL MOISTURE BEHIND THE FRONT WILL PROVIDE MVFR FOG AND IFR-MVFR CEILINGS. && .UPDATE... WILL UPDATE FORECAST TO ADJUST POPS. WILL HIGHER POPS ACROSS THE FAR WESTERN BORDERS AND LOWER THEM FURTHER EAST. SURFACE LOW CENTER WHICH IS REMNANTS OF GUSTAV IS NOW OVER SOUTHEAST MISSOURI WITH SURFACE WARM FRONT EXTENDING ACROSS NORTHERN OH/IN. 12Z NAM IN LINE WITH CURRENT RADAR TRENDS WITH BULK OF PRECIPITATION JUST WEST OF THE CWA. THIS IS WHERE SHEARED OUT 500MB VORTICITY AND MID LEVEL ISENTROPIC LIFT IS INTERACTING WITH TROPICAL MOISTURE PLUME FROM GUSTAV. SURFACE LOW WILL MOVE TO EAST CENTRAL ILLINOIS BY THIS EVENING WITH SURFACE WARM FRONT NUDGING SLIGHTLY NORTHWARD. THIS WILL KEEP MAIN PRECIP BAND BASICALLY IN THE SAME AREA WITH A EASTWARD EXPANSION THIS AFTERNOON WITH DAYTIME HEATING...MAINLY INTO THE THUMB REGION. MOST OF THE DETROIT AREA ON SOUTH WILL REMAIN DRY DURING THE AFTERNOON BUT WILL STILL CARRY A CHANCE FOR A SHOWER OR THUNDERSTORM WITH WARM FRONT JUST TO THE SOUTH. && .PREV DISCUSSION...ISSUED 420 AM EDT THU SEP 4 2008 SHORT TERM...TODAY EARLY MORNING SFC ANALYSIS SHOWING THE REMAINS OF `GUSTAV` NOW AS AN EXTRATROPICAL LOW CENTERED OVER ARKANSAS...WHILE AN ATTENDANT FRONTAL BOUNDARY EXTENDS NORTHEAST INTO THE OHIO VALLEY. DEEP TROPICAL MOISTURE PLUME NOW WRAPPING AROUND THE LOW LEVEL CIRCULATION...AS EVIDENCED BY THE SUBSTANTIAL MID/HIGH LEVEL CLOUD DEBRIS ALREADY BLANKETING MUCH OF THE GREAT LAKES AND AN AREA OF SHOWERS EXPANDING NORTH ACROSS WESTERN PORTION OF INDIANA. IN ADDITION...PLENTY OF RESIDUAL MOISTURE LEFT BEHIND BY EARLIER RAINFALL MAINTAINING A STUBBORN STRATUS DECK...ESPECIALLY ALONG/SOUTH OF THE I-69 CORRIDOR. REMNANTS OF `GUSTAV` WILL BEGIN TO EJECT NORTHEAST TODAY IN RESPONSE TO A DEEPENING SHORTWAVE LIFTING INTO THE PLAINS. THIS WILL ALLOW THE FRONTAL BOUNDARY TO RETURN NORTH AS A WARM FRONT...APPROACHING THE OH/MI BORDER BY LATE AFTERNOON AS THE SFC LOW PUSHES INTO IL. LATEST WATER VAPOR/RUC ANALYSIS INDICATE WEAKER SHORTWAVES SHEARING NORTHEAST OUT AHEAD OF MAIN CIRCULATION. THE PRESENCE OF THESE LARGER SCALE FEATURES INDICATES FORCING WILL BE SUFFICIENT TO JUSTIFY AT LEAST CHANCE POPS FOR TODAY GIVEN THE DEGREE OF DEEPER MOISTURE ADVECTION/MODEST ISENTROPIC ACCENT. THE DEEPEST MOISTURE AXIS/HIGHEST PRECIP AMOUNTS WILL REMAIN JUST SOUTH AND WEST OF THE AREA TODAY...LEAVING THE HIGHEST POPS OVER THE SAGINAW VALLEY AND LOWEST ACROSS THE MONROE-DETROIT-PORT HURON CORRIDOR. CLOUD COVER/LIMITED INSOLATION WILL KEEP SFC BASED INSTABILITY TO A MINIMUM...BUT MODELS DO SUGGEST SOME ELEVATED INSTABILITY WILL BE PRESENT AROUND 850 MB...SO WILL RETAIN THE MENTION OF THUNDER. THE DIURNAL TEMPERATURE RECOVERY WILL BE RESTRICTED TODAY BY THE PREDOMINANT PRE-FRONTAL NORTHEAST-EAST GRADIENT...WITH THE STRATUS LIKELY CUTTING INTO READINGS SOME DURING THE MORNING. OVERALL... WILL UNDERCUT GUIDANCE SLIGHTLY (ESPECIALLY NORTH)...WITH HIGHS RANGING FROM THE MID 70S SOUTH TO AROUND 70 ACROSS THE NORTH. LONG TERM...TONIGHT THROUGH NEXT WEDNESDAY JOSTLING AMONGST THE LATEST MEDIUM RANGE SUITE CONTINUES IN REGARDS TO THE SURFACE LOW TRACK SET FOR TONIGHT. THIS ISN`T ALL THAT DISCONCERTING...SINCE THE OSCILLATORY SOLUTION BEHAVIOR SUGGESTS A CONSENSUS. A SECOND POTENTIAL VORTICITY ANOMALY..NOW DIGGING THROUGH MONTANA...WILL ALLOW FOR A VERY QUICK EJECTION TO THE REMNANTS OF GUSTAV. THE LOW IS EXPECTED TO TRACK FROM FAR WEST CENTRAL INDIANA AT 00Z TONIGHT..THRU FNT/MBS...AND OFF THE TIP OF THE THUMB BY 12Z FRIDAY (COULD VERY WELL THEN SEE A SLIGHT DRIFT TO THE NORTHWEST ONCE THE LOW INTERACTS WITH LAKE HURON). HAVE ACCOUNTED FOR THE SLIGHT SOUTHWARD SHIFT BY INCLUDING PORTIONS OF LIVINGSTON/OAKLAND/LAPEER/SANILAC COUNTIES IN THE CATEGORICAL POPS. THERE WILL BE A FAIRLY TIGHT RAINFALL GRADIENT ACROSS THE SOUTHEASTERN CWA AS BUFFER SOUNDINGS EXHIBIT A WARM SECTOR DRY LAYER PERSISTING THROUGH 5KFT AGL. WILL CONTINUE THE CHANCE FOR THUNDER...ALTHOUGH NOT EXPECTED TO BE WIDESPREAD GIVEN THE NIGHTTIME PASSAGE AND MOIST ADIABATIC LAPSE RATES. HEAVY RAINFALL IS A DISTINCT POSSIBILITY (ONGOING AT 00Z) ALONG AND TO THE COOL SIDE OF THE SURFACE LOW WITH PWATS ONCE AGAIN APPROACHING 2.0 INCHES. HOWEVER...NO ISSUES ARE ANTICIPATED GIVEN THE DRY GROUND AND TRANSIENT NATURE OF THE PRECIPITATION. RAISED LOWS TONIGHT QUITE A BIT...GIVEN A MIXED COLUMN/WAA/CLOUDS 60S FOR MOST AREAS TO NEAR 70 FOR THE METRO. THE LOW WILL BE MOVING...SO EXPECTATIONS ARE FOR A RAPID EXIT OF ANY PRECIPITATION FRIDAY MORNING. THE ONLY CAVEAT TO THIS IS A SATURATED PBL AND RESULTANT LIGHT SHOWERS/DRIZZLE. DRY AIR ENTRAINMENT MAY EVENTUALLY WIN OUT ON FRIDAY...BUT EXPECT OVERCAST TO MOSTLY CLOUDY SKIES. HIGHS ARE EXPECTED TO REACH THE LOWER 70S NORTH TO UPPER 70S SOUTH. A QUIET STRETCH OF WEATHER IS EXPECTED FROM FRIDAY AFTERNOON THROUGH SATURDAY NIGHT. POST SYSTEM SUBSIDENCE AND WEAK SURFACE RIDGING SHOULD SHOULD PROVIDE FOR THE DRY CONDITIONS. A SMALLER POCKET OF INSTABILITY RESIDES BETWEEN 800 AND 700MB SATURDAY AND SHOULD ALLOW FOR PLENTY OF DIURNAL CUMULUS. HIGHS WILL REACH THE 70S. ACTIVE WEATHER RETURNS AND CARRIES OUT THE REMAINDER OF THE LONG TERM WITH THE ESTABLISHMENT OF HIGH ENERGY WESTERLY FLOW. TWO SIZABLE WAVES ARE EXPECTED TO PASS THROUGH THE GREAT LAKES REGION...THE FIRST ON SUNDAY AND THE SECOND IN QUICK SUCCESSION MONDAY. THE CURRENT FORECAST HAS THIS TIMEFRAME HANDLED WELL WITH THE CONTINUED RAIN MENTION. HIGHS TEMPERATURES FOR THE FIRST PART OF NEXT WEEK SHOULD CONSISTENTLY CHECK IN AROUND 5 DEGREES BELOW NORMAL. MARINE... A PREDOMINANT NORTHEAST WIND AND COOLER AIR MOVING ACROSS THE WARMER LAKE WATERS WILL MAINTAIN HIGHER WAVES TODAY OVER THE FAVORED LOCATIONS FROM OUTER SAGINAW BAY DOWN THROUGH THE NEARSHORE WATERS AT PORT HURON. WINDS WILL STRENGTHEN LATE TODAY...AND ESPECIALLY TONIGHT...AS THE PRESSURE GRADIENT TIGHTENS UPON THE APPROACH OF THE REMNANTS OF `GUSTAV`. THIS LOW PRESSURE SYSTEM WILL TRACK ACROSS CENTRAL LAKE HURON BY FRIDAY MORNING. THIS WILL LEAD TO WIND GUSTS OVER 25 KNOTS TONIGHT AND EARLY FRIDAY...PROMPTING THE INCLUSION OF ALL MARINE AREAS INTO A SMALL CRAFT ADVISORY FOR TONIGHT AND FRIDAY. WINDS ACROSS THE LAKE HURON OPENWATERS LOOK TO REMAIN JUST BELOW GALE FORCE...WITH GUSTS UP TO 30 KNOTS. MORE FAVORABLE MARINE CONDITIONS WILL DEVELOP ON SATURDAY AS A HIGH PRESSURE RIDGE EXPANDS INTO THE GREAT LAKES. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON... SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON INCLUDING OUTER SAGINAW BAY...UNTIL 4 PM FRIDAY. SMALL CRAFT ADVISORY...INNER SAGINAW BAY...FROM 4 PM THURSDAY TO 4 PM FRIDAY. LAKE ST CLAIR... SMALL CRAFT ADVISORY...FROM 4 PM THURSDAY TO 4 PM FRIDAY. MI WATERS OF LAKE ERIE... SMALL CRAFT ADVISORY...FROM 4 PM THURSDAY TO 4 PM FRIDAY. && $$ UPDATE.......DRC AVIATION.....DRC SHORT TERM...MR LONG TERM....CB MARINE.......MR YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 126 PM EDT THU SEP 4 2008 UPDATED FOR 18Z TAF ISSUANCE .UPDATE (ISSUED AT 952 AM EDT)... ISSUED NEW GRIDS AND ZFP TO INCORPORATE INCREASED CLOUD COVER ACROSS THE ENTIRE CWA GIVEN MID DECK ALREADY OVERHEAD...AND HIGHER POPS LATE THIS AFTERNOON AND TONIGHT ACROSS THE EASTERN FRINGE COUNTIES. HAVE NOT GONE AS FAR AS THE 06Z GFS WITH PRECIPITATION RAPIDLY MOVING NORTHWARD...BUT WILL CONTINUE TO MONITOR THE LATEST RADAR TRENDS AND UPDATE IF NEEDED. && .DISCUSSION... WATER VAPOR LOOP AND RUC ANALYSIS SHOWS A MID-LVL TROF OVER SCNTRL CANADA THROUGH THE PLAINS STATES WITH RIDGING DOWNSTREAM OVER THE ERN CONUS. FEATURE OF INTEREST FOR UPR MI WEATHER TODAY INTO EARLY FRI IS REMNANTS OF GUSTAV CIRCULATING OVER ARKANSAS ATTM NOW LIFTING NORTH. 800-600 MB DEFORMATION/FGEN AXIS AHEAD OF GUSTAV REMNANTS SUPPORTING EXPANSION OF RAIN INTO SRN WI EARLY THIS MORNING AS THIN CIRRUS SHIELD EXTENDS NORTH INTO THE UPR GREAT LAKES. TODAY...MODELS MAYBE HAVE TRENDED SLIGHTLY EWD WITH REMNANTS OF GUSTAV AND ASSOC SHORTWAVE...TRACKING SFC LOW THROUGH THUMB OF LWR MI BY 12Z. MODELS FAIRLY CONSISTENT SHOWING 800-600 MB DEFORMATION/FGEN SUPPORT AS PCPN SPREADS NORTH INTO CENTRAL AND ERN SECTIONS OF THE FCST AREA THIS AFTERNOON WITH BEST PCPN EXPECTED FOR COUNTIES ALONG LAKE MI. TONIGHT...STILL EXPECT WIDESPREAD RAIN TO BE ACROSS THE SE PORTION OF THE CWA AS THE SHORTWAVE TROUGH LIFTS THROUGH THE GREAT LAKES. PCPN AGAIN WILL BE SUPPORTED BY STRONG 800-600 MB DEFORMATION/FGEN AND 300K-305K ISENTROPIC ASCENT LEFT OF THE 850 MB LOW TRACKING INTO NRN LOWER MI. MODELS INDICATE THE HEAVIEST QPF WILL STAY OVER NRN LWR MI AND LAKE MI...BUT .50 INCH AMOUNTS OF RAIN ARE POSSIBLE OVER SCNTRL AND ERN COUNTIES OF THE FCST AREA. WILL KEEP CATEGORICAL POPS OVER THESE COUNTIES AND TAPER TO LOW CHC POPS OVER BARAGA AND IRON COUNTIES WHICH LOOK TO BE ON THE FAR WRN EDGE OF THE PCPN SHIELD. FRI AND FRI NIGHT...LINGERING PCPN OVER THE EAST SHOULD END EARLY FRI MORNING AS THE SHORTWAVE AND LOW LIFT QUICKLY NORTHEAST OF THE REGION. WEAK RIDGING BUILDING INTO THE AREA BEHIND THE SHORTWAVE SHOULD BRING SOME PARTIAL CLEARING BY FRI AFTERNOON. GFS AND ECMWF STILL INDICATE A WEAK SHORTWAVE AND ASSOC SFC TROF COULD BRING IN A FEW LIGHT SHOWERS OR SPRINKLES TO WRN SECTIONS OF THE FCST AREA FRI NIGHT. SAT INTO SUN...WITH THE POTENTIAL FOR ADDITIONAL SHORTWAVES MOVING THROUGH THE UPR GREAT LAKES IN BASE OF BROAD UPR TROF WILL KEEP PCPN CHANCES GOING INTO THE WEEKEND. WILL ALSO KEEP A MENTION OF THUNDER IN THE DAYTIME AS MODELS STILL HAVE FCST SBCAPE VALUES OF A FEW HUNDRED J/KG. . && .AVIATION (FOR THE 18Z TAF ISSUANCE)... EXPECT VFR CONDITIONS TO PREVAIL AT KCMX THRU THIS FCST PERIOD AS THE INFLUENCE OF WHAT USE TO BE GUSTAV MOVE TO THE EAST. HOWEVER...THERE IS SOME CONCERN THAT LOW CLOUDS OF THE HIGH MVFR VARIETY COULD DEVELOP TONIGHT...DUE TO EASTERLY FLOW UPSLOPING MOISTURE FROM RAIN THAT FALLS ON EASTERN LAKE SUPERIOR. AT SAW LOW END MVFR AND POSSIBLE IFR...DEPENDING ON HOW MUCH PRECIPITATION FALLS...WILL BE POSSIBLE WILL THE ABUNDANT MOISTURE AND CONTINUED NORTHEASTERLY UPSLOPE WINDS. INCLUDED FOG AT SAW. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... NE WINDS OF UP TO 25 KT STILL PERSIST ON EASTERN LAKE SUPERIOR. THESE SHOULD COME DOWN A FEW KNOTS TODAY...BUT THAT IS ABOUT IT WITH HIGH PRESSURE CENTERED OVER NORTHERN ONTARIO AND THE REMNANTS OF HURRICANE GUSTAV MOVING NE TOWARDS THE GREAT LAKES. IN FACT...NE WINDS OVER WRN LAKE SUPERIOR SHOULD INCREASE UP TO 25 KT LATER TODAY AS GUSTAV APPROACHES. TONIGHT...AS THE REMNANTS MOVE NORTHEAST ACROSS LOWER MI...THE NE WINDS OVER WRN LAKE SUPERIOR WILL DIMINISH UNDER 20 KT...WHILE INCREASING TO 25 KT ON ERN LAKE SUPERIOR. HIGH PRESSURE WILL REBUILD IN OVER LAKE SUPERIOR ON FRIDAY...ALLOWING WINDS ACROSS THE ENTIRE LAKE TO DIMINISH UNDER 20 KT. A SURFACE IS EXPECTED TO MOVE SW TO NE ACROSS LAKE SUPERIOR LATE FRI NIGHT INTO SAT...BUT WINDS SHOULD REMAIN AT OR BELOW 20 KT. A LOW PRESSURE AREA OR COLD FRONT IS PLANNED TO DROP SE ACROSS LAKE SUPERIOR LATE SUN. NORTH TO NE WINDS BEHIND THE FRONT FOR SUN NIGHT AND MON COULD APPROACH 20 KT OR HIGHER...BUT CONSIDERABLE UNCERTAINTY EXISTS REGARDING THE STRENGTH OF THE LOW/COLD FRONT AND TIMING. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ UPDATE...KF DISCUSSION...VOSS AVIATION...KF MARINE...AJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1030 AM EDT THU SEP 4 2008 .UPDATE... WILL UPDATE FORECAST TO ADJUST POPS. WILL HIGHER POPS ACROSS THE FAR WESTERN BORDERS AND LOWER THEM FURTHER EAST. SURFACE LOW CENTER WHICH IS REMNANTS OF GUSTAV IS NOW OVER SOUTHEAST MISSOURI WITH SURFACE WARM FRONT EXTENDING ACROSS NORTHERN OH/IN. 12Z NAM IN LINE WITH CURRENT RADAR TRENDS WITH BULK OF PRECIPITATION JUST WEST OF THE CWA. THIS IS WHERE SHEARED OUT 500MB VORTICITY AND MID LEVEL ISENTROPIC LIFT IS INTERACTING WITH TROPICAL MOISTURE PLUME FROM GUSTAV. SURFACE LOW WILL MOVE TO EAST CENTRAL ILLINOIS BY THIS EVENING WITH SURFACE WARM FRONT NUDGING SLIGHTLY NORTHWARD. THIS WILL KEEP MAIN PRECIP BAND BASICALLY IN THE SAME AREA WITH A EASTWARD EXPANSION THIS AFTERNOON WITH DAYTIME HEATING...MAINLY INTO THE THUMB REGION. MOST OF THE DETROIT AREA ON SOUTH WILL REMAIN DRY DURING THE AFTERNOON BUT WILL STILL CARRY A CHANCE FOR A SHOWER OR THUNDERSTORM WITH WARM FRONT JUST TO THE SOUTH. && .AVIATION... LINGERING MVFR STRATUS AT DTW/DET WILL SLOWLY LIFT INTO VFR THROUGH MID MORNING AS MIXING COMMENCES. VFR CONDITIONS UNDER A BROAD CANOPY OF THICK HIGHER CLOUDINESS WILL THEN HOLD INTO THE EARLY EVENING HOURS FROM FNT SOUTHWARD. DEEP TROPICAL MOISTURE WILL BEGIN TO SHIFT NORTHWARD THROUGH THE DAY IN ADVANCE OF A LOW PRESSURE SYSTEM. MBS WILL LIE ON THE EASTERN FRINGES OF THIS MOISTURE THROUGHOUT THE DAY...KEEPING CONDITIONS AT MARGINAL MVFR LEVELS WITH SCATTERED SHOWERS IN THE VICINITY OF THE TERMINAL. CONDITIONS WILL DETERIORATE INTO MVFR...AND POTENTIALLY IFR...BETWEEN 00-06Z AT ALL TERMINALS AS THE SFC LOW LIFTS THROUGH AND DRAGS A COLD FRONT ACROSS THE REGION. WILL HIGHLIGHT THE BEST CHANCE FOR THUNDER AT MBS AND FNT WITH A TEMPO GROUP...WHILE HOLDING OFF ON MENTIONING THUNDERSTORMS YET AT THE DETROIT AIRPORTS WITH INSTABILITY RAPIDLY DECREASING BY THE TIME THIS DEEPER MOISTURE AXIS ARRIVES. && .PREV DISCUSSION...ISSUED 420 AM EDT THU SEP 4 2008 SHORT TERM...TODAY EARLY MORNING SFC ANALYSIS SHOWING THE REMAINS OF `GUSTAV` NOW AS AN EXTRATROPICAL LOW CENTERED OVER ARKANSAS...WHILE AN ATTENDANT FRONTAL BOUNDARY EXTENDS NORTHEAST INTO THE OHIO VALLEY. DEEP TROPICAL MOISTURE PLUME NOW WRAPPING AROUND THE LOW LEVEL CIRCULATION...AS EVIDENCED BY THE SUBSTANTIAL MID/HIGH LEVEL CLOUD DEBRIS ALREADY BLANKETING MUCH OF THE GREAT LAKES AND AN AREA OF SHOWERS EXPANDING NORTH ACROSS WESTERN PORTION OF INDIANA. IN ADDITION...PLENTY OF RESIDUAL MOISTURE LEFT BEHIND BY EARLIER RAINFALL MAINTAINING A STUBBORN STRATUS DECK...ESPECIALLY ALONG/SOUTH OF THE I-69 CORRIDOR. REMNANTS OF `GUSTAV` WILL BEGIN TO EJECT NORTHEAST TODAY IN RESPONSE TO A DEEPENING SHORTWAVE LIFTING INTO THE PLAINS. THIS WILL ALLOW THE FRONTAL BOUNDARY TO RETURN NORTH AS A WARM FRONT...APPROACHING THE OH/MI BORDER BY LATE AFTERNOON AS THE SFC LOW PUSHES INTO IL. LATEST WATER VAPOR/RUC ANALYSIS INDICATE WEAKER SHORTWAVES SHEARING NORTHEAST OUT AHEAD OF MAIN CIRCULATION. THE PRESENCE OF THESE LARGER SCALE FEATURES INDICATES FORCING WILL BE SUFFICIENT TO JUSTIFY AT LEAST CHANCE POPS FOR TODAY GIVEN THE DEGREE OF DEEPER MOISTURE ADVECTION/MODEST ISENTROPIC ACCENT. THE DEEPEST MOISTURE AXIS/HIGHEST PRECIP AMOUNTS WILL REMAIN JUST SOUTH AND WEST OF THE AREA TODAY...LEAVING THE HIGHEST POPS OVER THE SAGINAW VALLEY AND LOWEST ACROSS THE MONROE-DETROIT-PORT HURON CORRIDOR. CLOUD COVER/LIMITED INSOLATION WILL KEEP SFC BASED INSTABILITY TO A MINIMUM...BUT MODELS DO SUGGEST SOME ELEVATED INSTABILITY WILL BE PRESENT AROUND 850 MB...SO WILL RETAIN THE MENTION OF THUNDER. THE DIURNAL TEMPERATURE RECOVERY WILL BE RESTRICTED TODAY BY THE PREDOMINANT PRE-FRONTAL NORTHEAST-EAST GRADIENT...WITH THE STRATUS LIKELY CUTTING INTO READINGS SOME DURING THE MORNING. OVERALL... WILL UNDERCUT GUIDANCE SLIGHTLY (ESPECIALLY NORTH)...WITH HIGHS RANGING FROM THE MID 70S SOUTH TO AROUND 70 ACROSS THE NORTH. LONG TERM...TONIGHT THROUGH NEXT WEDNESDAY JOSTLING AMONGST THE LATEST MEDIUM RANGE SUITE CONTINUES IN REGARDS TO THE SURFACE LOW TRACK SET FOR TONIGHT. THIS ISN`T ALL THAT DISCONCERTING...SINCE THE OSCILLATORY SOLUTION BEHAVIOR SUGGESTS A CONSENSUS. A SECOND POTENTIAL VORTICITY ANOMALY..NOW DIGGING THROUGH MONTANA...WILL ALLOW FOR A VERY QUICK EJECTION TO THE REMNANTS OF GUSTAV. THE LOW IS EXPECTED TO TRACK FROM FAR WEST CENTRAL INDIANA AT 00Z TONIGHT..THRU FNT/MBS...AND OFF THE TIP OF THE THUMB BY 12Z FRIDAY (COULD VERY WELL THEN SEE A SLIGHT DRIFT TO THE NORTHWEST ONCE THE LOW INTERACTS WITH LAKE HURON). HAVE ACCOUNTED FOR THE SLIGHT SOUTHWARD SHIFT BY INCLUDING PORTIONS OF LIVINGSTON/OAKLAND/LAPEER/SANILAC COUNTIES IN THE CATEGORICAL POPS. THERE WILL BE A FAIRLY TIGHT RAINFALL GRADIENT ACROSS THE SOUTHEASTERN CWA AS BUFFER SOUNDINGS EXHIBIT A WARM SECTOR DRY LAYER PERSISTING THROUGH 5KFT AGL. WILL CONTINUE THE CHANCE FOR THUNDER...ALTHOUGH NOT EXPECTED TO BE WIDESPREAD GIVEN THE NIGHTTIME PASSAGE AND MOIST ADIABATIC LAPSE RATES. HEAVY RAINFALL IS A DISTINCT POSSIBILITY (ONGOING AT 00Z) ALONG AND TO THE COOL SIDE OF THE SURFACE LOW WITH PWATS ONCE AGAIN APPROACHING 2.0 INCHES. HOWEVER...NO ISSUES ARE ANTICIPATED GIVEN THE DRY GROUND AND TRANSIENT NATURE OF THE PRECIPITATION. RAISED LOWS TONIGHT QUITE A BIT...GIVEN A MIXED COLUMN/WAA/CLOUDS 60S FOR MOST AREAS TO NEAR 70 FOR THE METRO. THE LOW WILL BE MOVING...SO EXPECTATIONS ARE FOR A RAPID EXIT OF ANY PRECIPITATION FRIDAY MORNING. THE ONLY CAVEAT TO THIS IS A SATURATED PBL AND RESULTANT LIGHT SHOWERS/DRIZZLE. DRY AIR ENTRAINMENT MAY EVENTUALLY WIN OUT ON FRIDAY...BUT EXPECT OVERCAST TO MOSTLY CLOUDY SKIES. HIGHS ARE EXPECTED TO REACH THE LOWER 70S NORTH TO UPPER 70S SOUTH. A QUIET STRETCH OF WEATHER IS EXPECTED FROM FRIDAY AFTERNOON THROUGH SATURDAY NIGHT. POST SYSTEM SUBSIDENCE AND WEAK SURFACE RIDGING SHOULD SHOULD PROVIDE FOR THE DRY CONDITIONS. A SMALLER POCKET OF INSTABILITY RESIDES BETWEEN 800 AND 700MB SATURDAY AND SHOULD ALLOW FOR PLENTY OF DIURNAL CUMULUS. HIGHS WILL REACH THE 70S. ACTIVE WEATHER RETURNS AND CARRIES OUT THE REMAINDER OF THE LONG TERM WITH THE ESTABLISHMENT OF HIGH ENERGY WESTERLY FLOW. TWO SIZABLE WAVES ARE EXPECTED TO PASS THROUGH THE GREAT LAKES REGION...THE FIRST ON SUNDAY AND THE SECOND IN QUICK SUCCESSION MONDAY. THE CURRENT FORECAST HAS THIS TIMEFRAME HANDLED WELL WITH THE CONTINUED RAIN MENTION. HIGHS TEMPERATURES FOR THE FIRST PART OF NEXT WEEK SHOULD CONSISTENTLY CHECK IN AROUND 5 DEGREES BELOW NORMAL. MARINE... A PREDOMINANT NORTHEAST WIND AND COOLER AIR MOVING ACROSS THE WARMER LAKE WATERS WILL MAINTAIN HIGHER WAVES TODAY OVER THE FAVORED LOCATIONS FROM OUTER SAGINAW BAY DOWN THROUGH THE NEARSHORE WATERS AT PORT HURON. WINDS WILL STRENGTHEN LATE TODAY...AND ESPECIALLY TONIGHT...AS THE PRESSURE GRADIENT TIGHTENS UPON THE APPROACH OF THE REMNANTS OF `GUSTAV`. THIS LOW PRESSURE SYSTEM WILL TRACK ACROSS CENTRAL LAKE HURON BY FRIDAY MORNING. THIS WILL LEAD TO WIND GUSTS OVER 25 KNOTS TONIGHT AND EARLY FRIDAY...PROMPTING THE INCLUSION OF ALL MARINE AREAS INTO A SMALL CRAFT ADVISORY FOR TONIGHT AND FRIDAY. WINDS ACROSS THE LAKE HURON OPENWATERS LOOK TO REMAIN JUST BELOW GALE FORCE...WITH GUSTS UP TO 30 KNOTS. MORE FAVORABLE MARINE CONDITIONS WILL DEVELOP ON SATURDAY AS A HIGH PRESSURE RIDGE EXPANDS INTO THE GREAT LAKES. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON... SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON INCLUDING OUTER SAGINAW BAY...UNTIL 4 PM FRIDAY. SMALL CRAFT ADVISORY...INNER SAGINAW BAY...FROM 4 PM THURSDAY TO 4 PM FRIDAY. LAKE ST CLAIR... SMALL CRAFT ADVISORY...FROM 4 PM THURSDAY TO 4 PM FRIDAY. MI WATERS OF LAKE ERIE... SMALL CRAFT ADVISORY...FROM 4 PM THURSDAY TO 4 PM FRIDAY. && $$ UPDATE.......DRC AVIATION.....MR SHORT TERM...MR LONG TERM....CB MARINE.......MR YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 952 AM EDT THU SEP 4 2008 .UPDATE... ISSUED NEW GRIDS AND ZFP TO INCORPORATE INCREASED CLOUD COVER ACROSS THE ENTIRE CWA GIVEN MID DECK ALREADY OVERHEAD...AND HIGHER POPS LATE THIS AFTERNOON AND TONIGHT ACROSS THE EASTERN FRINGE COUNTIES. HAVE NOT GONE AS FAR AS THE 06Z GFS WITH PRECIPITATION RAPIDLY MOVING NORTHWARD...BUT WILL CONTINUE TO MONITOR THE LATEST RADAR TRENDS AND UPDATE IF NEEDED. && .DISCUSSION... WATER VAPOR LOOP AND RUC ANALYSIS SHOWS A MID-LVL TROF OVER SCNTRL CANADA THROUGH THE PLAINS STATES WITH RIDGING DOWNSTREAM OVER THE ERN CONUS. FEATURE OF INTEREST FOR UPR MI WEATHER TODAY INTO EARLY FRI IS REMNANTS OF GUSTAV CIRCULATING OVER ARKANSAS ATTM NOW LIFTING NORTH. 800-600 MB DEFORMATION/FGEN AXIS AHEAD OF GUSTAV REMNANTS SUPPORTING EXPANSION OF RAIN INTO SRN WI EARLY THIS MORNING AS THIN CIRRUS SHIELD EXTENDS NORTH INTO THE UPR GREAT LAKES. TODAY...MODELS MAYBE HAVE TRENDED SLIGHTLY EWD WITH REMNANTS OF GUSTAV AND ASSOC SHORTWAVE...TRACKING SFC LOW THROUGH THUMB OF LWR MI BY 12Z. MODELS FAIRLY CONSISTENT SHOWING 800-600 MB DEFORMATION/FGEN SUPPORT AS PCPN SPREADS NORTH INTO CENTRAL AND ERN SECTIONS OF THE FCST AREA THIS AFTERNOON WITH BEST PCPN EXPECTED FOR COUNTIES ALONG LAKE MI. TONIGHT...STILL EXPECT WIDESPREAD RAIN TO BE ACROSS THE SE PORTION OF THE CWA AS THE SHORTWAVE TROUGH LIFTS THROUGH THE GREAT LAKES. PCPN AGAIN WILL BE SUPPORTED BY STRONG 800-600 MB DEFORMATION/FGEN AND 300K-305K ISENTROPIC ASCENT LEFT OF THE 850 MB LOW TRACKING INTO NRN LOWER MI. MODELS INDICATE THE HEAVIEST QPF WILL STAY OVER NRN LWR MI AND LAKE MI...BUT .50 INCH AMOUNTS OF RAIN ARE POSSIBLE OVER SCNTRL AND ERN COUNTIES OF THE FCST AREA. WILL KEEP CATEGORICAL POPS OVER THESE COUNTIES AND TAPER TO LOW CHC POPS OVER BARAGA AND IRON COUNTIES WHICH LOOK TO BE ON THE FAR WRN EDGE OF THE PCPN SHIELD. FRI AND FRI NIGHT...LINGERING PCPN OVER THE EAST SHOULD END EARLY FRI MORNING AS THE SHORTWAVE AND LOW LIFT QUICKLY NORTHEAST OF THE REGION. WEAK RIDGING BUILDING INTO THE AREA BEHIND THE SHORTWAVE SHOULD BRING SOME PARTIAL CLEARING BY FRI AFTERNOON. GFS AND ECMWF STILL INDICATE A WEAK SHORTWAVE AND ASSOC SFC TROF COULD BRING IN A FEW LIGHT SHOWERS OR SPRINKLES TO WRN SECTIONS OF THE FCST AREA FRI NIGHT. SAT INTO SUN...WITH THE POTENTIAL FOR ADDITIONAL SHORTWAVES MOVING THROUGH THE UPR GREAT LAKES IN BASE OF BROAD UPR TROF WILL KEEP PCPN CHANCES GOING INTO THE WEEKEND. WILL ALSO KEEP A MENTION OF THUNDER IN THE DAYTIME AS MODELS STILL HAVE FCST SBCAPE VALUES OF A FEW HUNDRED J/KG. . && .AVIATION (FOR THE 12Z TAF ISSUANCE)... EXPECT VFR CONDITIONS TO PREVAIL AT KCMX THRU THIS FCST PERIOD. HOWEVER...THERE IS SOME CONCERN THAT LOW CLOUDS OF THE HIGH MVFR VARIETY COULD DEVELOP TONIGHT...DUE TO EASTERLY FLOW UPSLOPING MOISTURE FROM RAIN THAT FALLS ON EASTERN LAKE SUPERIOR. AT KSAW...OCCASIONAL MVFR CIGS COULD FORM BRIEFLY AT KSAW AS A COOL AIRMASS FLOWING ACROSS LAKE SUPERIOR UPSLOPES INTO NCNTRL UPPER MI. DAYTIME HEATING THROUGH HIGH CLOUDS COMBINED WITH DAYTIME HEATING WILL GET RID OF ANY LOW CLOUDS. LATER TODAY INTO TONIGHT...REMNANTS OF WHAT WAS ONCE HURRICANE GUSTAV WILL BE LIFTING INTO LOWER MI. WRN FRINGE OF RAIN SHIELD MAY BRUSH KSAW. IF SO...CONDITIONS WILL DETERIORATE TO LOW END MVFR (POSSIBLE IFR) THIS EVENING. IF RAIN DOESN`T REACH KSAW...CONDITIONS WILL LIKELY REMAIN VFR OR ONLY DROP TO UPPER END MVFR CIGS. THIS FCST CONTINUES TO REFLECT PESSIMISTIC CONDITIONS WITH RAIN DEVELOPMENT LATE AFTN/EVENING. ANY RAIN SHOULD EXIT AFTER MIDNIGHT...BUT LINGERING LOW LEVEL MOISTURE PLUS A NE WIND WILL LIKELY RESULT IN AN IFR DECK. HOWEVER...IF THE RAIN DOES MATERIALIZE...LIFR CLOUD BASES ARE CERTAINLY NOT OUT OF THE QUESTION. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... NE WINDS OF UP TO 25 KT STILL PERSIST ON EASTERN LAKE SUPERIOR. THESE SHOULD COME DOWN A FEW KNOTS TODAY...BUT THAT IS ABOUT IT WITH HIGH PRESSURE CENTERED OVER NORTHERN ONTARIO AND THE REMNANTS OF HURRICANE GUSTAV MOVING NE TOWARDS THE GREAT LAKES. IN FACT...NE WINDS OVER WRN LAKE SUPERIOR SHOULD INCREASE UP TO 25 KT LATER TODAY AS GUSTAV APPROACHES. TONIGHT...AS THE REMNANTS MOVE NORTHEAST ACROSS LOWER MI...THE NE WINDS OVER WRN LAKE SUPERIOR WILL DIMINISH UNDER 20 KT...WHILE INCREASING TO 25 KT ON ERN LAKE SUPERIOR. HIGH PRESSURE WILL REBUILD IN OVER LAKE SUPERIOR ON FRIDAY...ALLOWING WINDS ACROSS THE ENTIRE LAKE TO DIMINISH UNDER 20 KT. A SURFACE IS EXPECTED TO MOVE SW TO NE ACROSS LAKE SUPERIOR LATE FRI NIGHT INTO SAT...BUT WINDS SHOULD REMAIN AT OR BELOW 20 KT. A LOW PRESSURE AREA OR COLD FRONT IS PLANNED TO DROP SE ACROSS LAKE SUPERIOR LATE SUN. NORTH TO NE WINDS BEHIND THE FRONT FOR SUN NIGHT AND MON COULD APPROACH 20 KT OR HIGHER...BUT CONSIDERABLE UNCERTAINTY EXISTS REGARDING THE STRENGTH OF THE LOW/COLD FRONT AND TIMING. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ UPDATE...KF DISCUSSION...VOSS AVIATION...ROLFSON/AJ MARINE...AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 739 AM EDT THU SEP 4 2008 UPDATED AVIATION DISCUSSION FOR 12Z TAF ISSUANCE .DISCUSSION... WATER VAPOR LOOP AND RUC ANALYSIS SHOWS A MID-LVL TROF OVER SCNTRL CANADA THROUGH THE PLAINS STATES WITH RIDGING DOWNSTREAM OVER THE ERN CONUS. FEATURE OF INTEREST FOR UPR MI WEATHER TODAY INTO EARLY FRI IS REMNANTS OF GUSTAV CIRCULATING OVER ARKANSAS ATTM NOW LIFTING NORTH. 800-600 MB DEFORMATION/FGEN AXIS AHEAD OF GUSTAV REMNANTS SUPPORTING EXPANSION OF RAIN INTO SRN WI EARLY THIS MORNING AS THIN CIRRUS SHIELD EXTENDS NORTH INTO THE UPR GREAT LAKES. TODAY...MODELS MAYBE HAVE TRENDED SLIGHTLY EWD WITH REMNANTS OF GUSTAV AND ASSOC SHORTWAVE...TRACKING SFC LOW THROUGH THUMB OF LWR MI BY 12Z. MODELS FAIRLY CONSISTENT SHOWING 800-600 MB DEFORMATION/FGEN SUPPORT AS PCPN SPREADS NORTH INTO CENTRAL AND ERN SECTIONS OF THE FCST AREA THIS AFTERNOON WITH BEST PCPN EXPECTED FOR COUNTIES ALONG LAKE MI. TONIGHT...STILL EXPECT WIDESPREAD RAIN TO BE ACROSS THE SE PORTION OF THE CWA AS THE SHORTWAVE TROUGH LIFTS THROUGH THE GREAT LAKES. PCPN AGAIN WILL BE SUPPORTED BY STRONG 800-600 MB DEFORMATION/FGEN AND 300K-305K ISENTROPIC ASCENT LEFT OF THE 850 MB LOW TRACKING INTO NRN LOWER MI. MODELS INDICATE THE HEAVIEST QPF WILL STAY OVER NRN LWR MI AND LAKE MI...BUT .50 INCH AMOUNTS OF RAIN ARE POSSIBLE OVER SCNTRL AND ERN COUNTIES OF THE FCST AREA. WILL KEEP CATEGORICAL POPS OVER THESE COUNTIES AND TAPER TO LOW CHC POPS OVER BARAGA AND IRON COUNTIES WHICH LOOK TO BE ON THE FAR WRN EDGE OF THE PCPN SHIELD. FRI AND FRI NIGHT...LINGERING PCPN OVER THE EAST SHOULD END EARLY FRI MORNING AS THE SHORTWAVE AND LOW LIFT QUICKLY NORTHEAST OF THE REGION. WEAK RIDGING BUILDING INTO THE AREA BEHIND THE SHORTWAVE SHOULD BRING SOME PARTIAL CLEARING BY FRI AFTERNOON. GFS AND ECMWF STILL INDICATE A WEAK SHORTWAVE AND ASSOC SFC TROF COULD BRING IN A FEW LIGHT SHOWERS OR SPRINKLES TO WRN SECTIONS OF THE FCST AREA FRI NIGHT. SAT INTO SUN...WITH THE POTENTIAL FOR ADDITIONAL SHORTWAVES MOVING THROUGH THE UPR GREAT LAKES IN BASE OF BROAD UPR TROF WILL KEEP PCPN CHANCES GOING INTO THE WEEKEND. WILL ALSO KEEP A MENTION OF THUNDER IN THE DAYTIME AS MODELS STILL HAVE FCST SBCAPE VALUES OF A FEW HUNDRED J/KG. . && .AVIATION (FOR THE 12Z TAF ISSUANCE)... EXPECT VFR CONDITIONS TO PREVAIL AT KCMX THRU THIS FCST PERIOD. HOWEVER...THERE IS SOME CONCERN THAT LOW CLOUDS OF THE HIGH MVFR VARIETY COULD DEVELOP TONIGHT...DUE TO EASTERLY FLOW UPSLOPING MOISTURE FROM RAIN THAT FALLS ON EASTERN LAKE SUPERIOR. AT KSAW...OCCASIONAL MVFR CIGS COULD FORM BRIEFLY AT KSAW AS A COOL AIRMASS FLOWING ACROSS LAKE SUPERIOR UPSLOPES INTO NCNTRL UPPER MI. DAYTIME HEATING THROUGH HIGH CLOUDS COMBINED WITH DAYTIME HEATING WILL GET RID OF ANY LOW CLOUDS. LATER TODAY INTO TONIGHT...REMNANTS OF WHAT WAS ONCE HURRICANE GUSTAV WILL BE LIFTING INTO LOWER MI. WRN FRINGE OF RAIN SHIELD MAY BRUSH KSAW. IF SO...CONDITIONS WILL DETERIORATE TO LOW END MVFR (POSSIBLE IFR) THIS EVENING. IF RAIN DOESN`T REACH KSAW...CONDITIONS WILL LIKELY REMAIN VFR OR ONLY DROP TO UPPER END MVFR CIGS. THIS FCST CONTINUES TO REFLECT PESSIMISTIC CONDITIONS WITH RAIN DEVELOPMENT LATE AFTN/EVENING. ANY RAIN SHOULD EXIT AFTER MIDNIGHT...BUT LINGERING LOW LEVEL MOISTURE PLUS A NE WIND WILL LIKELY RESULT IN AN IFR DECK. HOWEVER...IF THE RAIN DOES MATERIALIZE...LIFR CLOUD BASES ARE CERTAINLY NOT OUT OF THE QUESTION. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... NE WINDS OF UP TO 25 KT STILL PERSIST ON EASTERN LAKE SUPERIOR. THESE SHOULD COME DOWN A FEW KNOTS TODAY...BUT THAT IS ABOUT IT WITH HIGH PRESSURE CENTERED OVER NORTHERN ONTARIO AND THE REMNANTS OF HURRICANE GUSTAV MOVING NE TOWARDS THE GREAT LAKES. IN FACT...NE WINDS OVER WRN LAKE SUPERIOR SHOULD INCREASE UP TO 25 KT LATER TODAY AS GUSTAV APPROACHES. TONIGHT...AS THE REMNANTS MOVE NORTHEAST ACROSS LOWER MI...THE NE WINDS OVER WRN LAKE SUPERIOR WILL DIMINISH UNDER 20 KT...WHILE INCREASING TO 25 KT ON ERN LAKE SUPERIOR. HIGH PRESSURE WILL REBUILD IN OVER LAKE SUPERIOR ON FRIDAY...ALLOWING WINDS ACROSS THE ENTIRE LAKE TO DIMINISH UNDER 20 KT. A SURFACE IS EXPECTED TO MOVE SW TO NE ACROSS LAKE SUPERIOR LATE FRI NIGHT INTO SAT...BUT WINDS SHOULD REMAIN AT OR BELOW 20 KT. A LOW PRESSURE AREA OR COLD FRONT IS PLANNED TO DROP SE ACROSS LAKE SUPERIOR LATE SUN. NORTH TO NE WINDS BEHIND THE FRONT FOR SUN NIGHT AND MON COULD APPROACH 20 KT OR HIGHER...BUT CONSIDERABLE UNCERTAINTY EXISTS REGARDING THE STRENGTH OF THE LOW/COLD FRONT AND TIMING. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ DISCUSSION...VOSS AVIATION...ROLFSON/AJ MARINE...AJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 709 AM EDT THU SEP 4 2008 .AVIATION... LINGERING MVFR STRATUS AT DTW/DET WILL SLOWLY LIFT INTO VFR THROUGH MID MORNING AS MIXING COMMENCES. VFR CONDITIONS UNDER A BROAD CANOPY OF THICK HIGHER CLOUDINESS WILL THEN HOLD INTO THE EARLY EVENING HOURS FROM FNT SOUTHWARD. DEEP TROPICAL MOISTURE WILL BEGIN TO SHIFT NORTHWARD THROUGH THE DAY IN ADVANCE OF A LOW PRESSURE SYSTEM. MBS WILL LIE ON THE EASTERN FRINGES OF THIS MOISTURE THROUGHOUT THE DAY...KEEPING CONDITIONS AT MARGINAL MVFR LEVELS WITH SCATTERED SHOWERS IN THE VICINITY OF THE TERMINAL. CONDITIONS WILL DETERIOTE INTO MVFR...AND POTENTIALLY IFR...BETWEEN 00-06Z AT ALL TERMINALS AS THE SFC LOW LIFTS THROUGH AND DRAGS A COLD FRONT ACROSS THE REGION. WILL HIGHLIGHT THE BEST CHANCE FOR THUNDER AT MBS AND FNT WITH A TEMPO GROUP...WHILE HOLDING OFF ON MENTIONING THUNDERSTORMS YET AT THE DETROIT AIRPORTS WITH INSTABILITY RAPIDLY DECREASING BY THE TIME THIS DEEPER MOISTURE AXIS ARRIVES. && .PREV DISCUSSION...ISSUED 420 AM EDT THU SEP 4 2008 SHORT TERM...TODAY EARLY MORNING SFC ANALYSIS SHOWING THE REMAINS OF `GUSTAV` NOW AS AN EXTRATROPICAL LOW CENTERED OVER ARKANSAS...WHILE AN ATTENDANT FRONTAL BOUNDARY EXTENDS NORTHEAST INTO THE OHIO VALLEY. DEEP TROPICAL MOISTURE PLUME NOW WRAPPING AROUND THE LOW LEVEL CIRCULATION...AS EVIDENCED BY THE SUBSTANTIAL MID/HIGH LEVEL CLOUD DEBRIS ALREADY BLANKETING MUCH OF THE GREAT LAKES AND AN AREA OF SHOWERS EXPANDING NORTH ACROSS WESTERN PORTION OF INDIANA. IN ADDITION...PLENTY OF RESIDUAL MOISTURE LEFT BEHIND BY EARLIER RAINFALL MAINTAINING A STUBBORN STRATUS DECK...ESPECIALLY ALONG/SOUTH OF THE I-69 CORRIDOR. REMNANTS OF `GUSTAV` WILL BEGIN TO EJECT NORTHEAST TODAY IN RESPONSE TO A DEEPENING SHORTWAVE LIFTING INTO THE PLAINS. THIS WILL ALLOW THE FRONTAL BOUNDARY TO RETURN NORTH AS A WARM FRONT...APPROACHING THE OH/MI BORDER BY LATE AFTERNOON AS THE SFC LOW PUSHES INTO IL. LATEST WATER VAPOR/RUC ANALYSIS INDICATE WEAKER SHORTWAVES SHEARING NORTHEAST OUT AHEAD OF MAIN CIRCULATION. THE PRESENCE OF THESE LARGER SCALE FEATURES INDICATES FORCING WILL BE SUFFICIENT TO JUSTIFY AT LEAST CHANCE POPS FOR TODAY GIVEN THE DEGREE OF DEEPER MOISTURE ADVECTION/MODEST ISENTROPIC ACCENT. THE DEEPEST MOISTURE AXIS/HIGHEST PRECIP AMOUNTS WILL REMAIN JUST SOUTH AND WEST OF THE AREA TODAY...LEAVING THE HIGHEST POPS OVER THE SAGINAW VALLEY AND LOWEST ACROSS THE MONROE-DETROIT-PORT HURON CORRIDOR. CLOUD COVER/LIMITED INSOLATION WILL KEEP SFC BASED INSTABILITY TO A MINIMUM...BUT MODELS DO SUGGEST SOME ELEVATED INSTABILITY WILL BE PRESENT AROUND 850 MB...SO WILL RETAIN THE MENTION OF THUNDER. THE DIURNAL TEMPERATURE RECOVERY WILL BE RESTRICTED TODAY BY THE PREDOMINANT PRE-FRONTAL NORTHEAST-EAST GRADIENT...WITH THE STRATUS LIKELY CUTTING INTO READINGS SOME DURING THE MORNING. OVERALL... WILL UNDERCUT GUIDANCE SLIGHTLY (ESPECIALLY NORTH)...WITH HIGHS RANGING FROM THE MID 70S SOUTH TO AROUND 70 ACROSS THE NORTH. LONG TERM...TONIGHT THROUGH NEXT WEDNESDAY JOSTLING AMONGST THE LATEST MEDIUM RANGE SUITE CONTINUES IN REGARDS TO THE SURFACE LOW TRACK SET FOR TONIGHT. THIS ISN`T ALL THAT DISCONCERTING...SINCE THE OSCILLATORY SOLUTION BEHAVIOR SUGGESTS A CONSENSUS. A SECOND POTENTIAL VORTICITY ANOMALY..NOW DIGGING THROUGH MONTANA...WILL ALLOW FOR A VERY QUICK EJECTION TO THE REMNANTS OF GUSTAV. THE LOW IS EXPECTED TO TRACK FROM FAR WEST CENTRAL INDIANA AT 00Z TONIGHT..THRU FNT/MBS...AND OFF THE TIP OF THE THUMB BY 12Z FRIDAY (COULD VERY WELL THEN SEE A SLIGHT DRIFT TO THE NORTHWEST ONCE THE LOW INTERACTS WITH LAKE HURON). HAVE ACCOUNTED FOR THE SLIGHT SOUTHWARD SHIFT BY INCLUDING PORTIONS OF LIVINGSTON/OAKLAND/LAPEER/SANILAC COUNTIES IN THE CATEGORICAL POPS. THERE WILL BE A FAIRLY TIGHT RAINFALL GRADIENT ACROSS THE SOUTHEASTERN CWA AS BUFFER SOUNDINGS EXHIBIT A WARM SECTOR DRY LAYER PERSISTING THROUGH 5KFT AGL. WILL CONTINUE THE CHANCE FOR THUNDER...ALTHOUGH NOT EXPECTED TO BE WIDESPREAD GIVEN THE NIGHTTIME PASSAGE AND MOIST ADIABATIC LAPSE RATES. HEAVY RAINFALL IS A DISTINCT POSSIBILITY (ONGOING AT 00Z) ALONG AND TO THE COOL SIDE OF THE SURFACE LOW WITH PWATS ONCE AGAIN APPROACHING 2.0 INCHES. HOWEVER...NO ISSUES ARE ANTICIPATED GIVEN THE DRY GROUND AND TRANSIENT NATURE OF THE PRECIPITATION. RAISED LOWS TONIGHT QUITE A BIT...GIVEN A MIXED COLUMN/WAA/CLOUDS 60S FOR MOST AREAS TO NEAR 70 FOR THE METRO. THE LOW WILL BE MOVING...SO EXPECTATIONS ARE FOR A RAPID EXIT OF ANY PRECIPITATION FRIDAY MORNING. THE ONLY CAVEAT TO THIS IS A SATURATED PBL AND RESULTANT LIGHT SHOWERS/DRIZZLE. DRY AIR ENTRAINMENT MAY EVENTUALLY WIN OUT ON FRIDAY...BUT EXPECT OVERCAST TO MOSTLY CLOUDY SKIES. HIGHS ARE EXPECTED TO REACH THE LOWER 70S NORTH TO UPPER 70S SOUTH. A QUIET STRETCH OF WEATHER IS EXPECTED FROM FRIDAY AFTERNOON THROUGH SATURDAY NIGHT. POST SYSTEM SUBSIDENCE AND WEAK SURFACE RIDGING SHOULD SHOULD PROVIDE FOR THE DRY CONDITIONS. A SMALLER POCKET OF INSTABILITY RESIDES BETWEEN 800 AND 700MB SATURDAY AND SHOULD ALLOW FOR PLENTY OF DIURNAL CUMULUS. HIGHS WILL REACH THE 70S. ACTIVE WEATHER RETURNS AND CARRIES OUT THE REMAINDER OF THE LONG TERM WITH THE ESTABLISHMENT OF HIGH ENERGY WESTERLY FLOW. TWO SIZABLE WAVES ARE EXPECTED TO PASS THROUGH THE GREAT LAKES REGION...THE FIRST ON SUNDAY AND THE SECOND IN QUICK SUCCESSION MONDAY. THE CURRENT FORECAST HAS THIS TIMEFRAME HANDLED WELL WITH THE CONTINUED RAIN MENTION. HIGHS TEMPERATURES FOR THE FIRST PART OF NEXT WEEK SHOULD CONSISTENTLY CHECK IN AROUND 5 DEGREES BELOW NORMAL. MARINE... A PREDOMINANT NORTHEAST WIND AND COOLER AIR MOVING ACROSS THE WARMER LAKE WATERS WILL MAINTAIN HIGHER WAVES TODAY OVER THE FAVORED LOCATIONS FROM OUTER SAGINAW BAY DOWN THROUGH THE NEARSHORE WATERS AT PORT HURON. WINDS WILL STRENGTHEN LATE TODAY...AND ESPECIALLY TONIGHT...AS THE PRESSURE GRADIENT TIGHTENS UPON THE APPROACH OF THE REMNANTS OF `GUSTAV`. THIS LOW PRESSURE SYSTEM WILL TRACK ACROSS CENTRAL LAKE HURON BY FRIDAY MORNING. THIS WILL LEAD TO WIND GUSTS OVER 25 KNOTS TONIGHT AND EARLY FRIDAY...PROMPTING THE INCLUSION OF ALL MARINE AREAS INTO A SMALL CRAFT ADVISORY FOR TONIGHT AND FRIDAY. WINDS ACROSS THE LAKE HURON OPENWATERS LOOK TO REMAIN JUST BELOW GALE FORCE...WITH GUSTS UP TO 30 KNOTS. MORE FAVORABLE MARINE CONDITIONS WILL DEVELOP ON SATURDAY AS A HIGH PRESSURE RIDGE EXPANDS INTO THE GREAT LAKES. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON... SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON INCLUDING OUTER SAGINAW BAY...UNTIL 4 PM FRIDAY. SMALL CRAFT ADVISORY...INNER SAGINAW BAY...FROM 4 PM THURSDAY TO 4 PM FRIDAY. LAKE ST CLAIR... SMALL CRAFT ADVISORY...FROM 4 PM THURSDAY TO 4 PM FRIDAY. MI WATERS OF LAKE ERIE... SMALL CRAFT ADVISORY...FROM 4 PM THURSDAY TO 4 PM FRIDAY. && $$ AVIATION.....MR SHORT TERM...MR LONG TERM....CB MARINE.......MR YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 420 AM EDT THU SEP 4 2008 .DISCUSSION... WATER VAPOR LOOP AND RUC ANALYSIS SHOWS A MID-LVL TROF OVER SCNTRL CANADA THROUGH THE PLAINS STATES WITH RIDGING DOWNSTREAM OVER THE ERN CONUS. FEATURE OF INTEREST FOR UPR MI WEATHER TODAY INTO EARLY FRI IS REMNANTS OF GUSTAV CIRCULATING OVER ARKANSAS ATTM NOW LIFTING NORTH. 800-600 MB DEFORMATION/FGEN AXIS AHEAD OF GUSTAV REMNANTS SUPPORTING EXPANSION OF RAIN INTO SRN WI EARLY THIS MORNING AS THIN CIRRUS SHIELD EXTENDS NORTH INTO THE UPR GREAT LAKES. TODAY...MODELS MAYBE HAVE TRENDED SLIGHTLY EWD WITH REMNANTS OF GUSTAV AND ASSOC SHORTWAVE...TRACKING SFC LOW THROUGH THUMB OF LWR MI BY 12Z. MODELS FAIRLY CONSISTENT SHOWING 800-600 MB DEFORMATION/FGEN SUPPORT AS PCPN SPREADS NORTH INTO CENTRAL AND ERN SECTIONS OF THE FCST AREA THIS AFTERNOON WITH BEST PCPN EXPECTED FOR COUNTIES ALONG LAKE MI. TONIGHT...STILL EXPECT WIDEPSREAD RAIN TO BE ACROSS THE SE PORTION OF THE CWA AS THE SHORTWAVE TROUGH LIFTS THROUGH THE GREAT LAKES. PCPN AGAIN WILL BE SUPPORTED BY STRONG 800-600 MB DEFORMATION/FGEN AND 300K-305K ISENTROPIC ASCENT LEFT OF THE 850 MB LOW TRACKING INTO NRN LOWER MI. MODELS INDICATE THE HEAVIEST QPF WILL STAY OVER NRN LWR MI AND LAKE MI...BUT .50 INCH AMOUNTS OF RAIN ARE POSSIBLE OVER SCNTRL AND ERN COUNTIES OF THE FCST AREA. WILL KEEP CATEGORICAL POPS OVER THESE COUNTIES AND TAPER TO LOW CHC POPS OVER BARAGA AND IRON COUNTIES WHICH LOOK TO BE ON THE FAR WRN EDGE OF THE PCPN SHIELD. FRI AND FRI NIGHT...LINGERING PCPN OVER THE EAST SHOULD END EARLY FRI MORNING AS THE SHORTWAVE AND LOW LIFT QUICKLY NORTHEAST OF THE REGION. WEAK RIDGING BUILDING INTO THE AREA BEHIND THE SHORTWAVE SHOULD BRING SOME PARTIAL CLEARING BY FRI AFTERNOON. GFS AND ECMWF STILL INDICATE A WEAK SHORTWAVE AND ASSOC SFC TROF COULD BRING IN A FEW LIGHT SHOWERS OR SPRINKLES TO WRN SECTIONS OF THE FCST AREA FRI NIGHT. SAT INTO SUN...WITH THE POTENTIAL FOR ADDITIONAL SHORTWAVES MOVING THROUGH THE UPR GREAT LAKES IN BASE OF BROAD UPR TROF WILL KEEP PCPN CHANCES GOING INTO THE WEEKEND. WILL ALSO KEEP A MENTION OF THUNDER IN THE DAYTIME AS MODELS STILL HAVE FCST SBCAPE VALUES OF A FEW HUNDRED J/KG. . && .AVIATION (FOR THE 06Z TAF ISSUANCE)... EXPECT VFR CONDITIONS TO PREVAIL AT KCMX THRU THIS FCST PERIOD. EARLY THIS MORNING...COOL AIRMASS FLOWING ACROSS LAKE SUPERIOR AND UPSLOPING INTO NCNTRL UPPER MI MAY RESULT IN OCCASIONAL MVFR CIGS AT KSAW FOR A FEW HRS AROUND SUNRISE. REMNANTS OF WHAT WAS ONCE HURRICANE GUSTAV WILL THEN BE LIFTING INTO THE GREAT LAKES THIS EVENING. WRN FRINGE OF RAIN SHIELD MAY BRUSH KSAW. IF SO... CONDITIONS WILL DETERIORATE TO LOW END MVFR (POSSIBLE IFR) THIS EVENING. IF RAIN DOESN`T REACH KSAW...CONDITIONS WILL LIKELY REMAIN VFR OR ONLY DROP TO UPPER END MVFR CIGS. THIS FCST WILL REFLECT PESSIMISTIC CONDITIONS WITH RAIN DEVELOPMENT LATE AFTN/EVENING. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... NE WINDS OF UP TO 25 KT STILL PERSIST ON EASTERN LAKE SUPERIOR. THESE SHOULD COME DOWN A FEW KNOTS TODAY...BUT THAT IS ABOUT IT WITH HIGH PRESSURE CENTERED OVER NORTHERN ONTARIO AND THE REMANTS OF HURRICANE GUSTAV MOVING NE TOWARDS THE GREAT LAKES. IN FACT...NE WINDS OVER WRN LAKE SUPERIOR SHOULD INCREASE UP TO 25 KT LATER TODAY AS GUSTAV APPROACHES. TONIGHT...AS THE REMNANTS MOVE NORTHEAST ACROSS LOWER MI...THE NE WINDS OVER WRN LAKE SUPERIOR WILL DIMINISH UNDER 20 KT...WHILE INCREASING TO 25 KT ON ERN LAKE SUPERIOR. HIGH PRESSURE WILL REBUILD IN OVER LAKE SUPERIOR ON FRIDAY...ALLOWING WINDS ACROSS THE ENTIRE LAKE TO DIMINISH UNDER 20 KT. A SURFACE IS EXPECTED TO MOVE SW TO NE ACROSS LAKE SUPERIOR LATE FRI NIGHT INTO SAT...BUT WINDS SHOULD REMAIN AT OR BELOW 20 KT. A LOW PRESSURE AREA OR COLD FRONT IS PLANNED TO DROP SE ACROSS LAKE SUPERIOR LATE SUN. NORTH TO NE WINDS BEHIND THE FRONT FOR SUN NIGHT AND MON COULD APPROACH 20 KT OR HIGHER...BUT CONSIDERABLE UNCERTAINTY EXISTS REGARDING THE STRENGTH OF THE LOW/COLD FRONT AND TIMING. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ DISCUSSION...VOSS AVIATION...ROLFSON MARINE...AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 130 PM EDT WED SEP 3 2008 UPDATED AVIATION DISCUSSION FOR 18Z TAF ISSUANCE .SYNOPSIS... WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL RIDGE OVER THE ERN GREAT LAKES INTO QUEBEC AND A TROF FROM MANITOBA INTO THE NRN PLAINS. THE REMNANTS OF TROPICAL STORM GUSTAV STILL CIRCULATING OVER THE TX/ARK BORDER WHILE TROPICAL STORM HANNA IS ORGANIZING NORTH OF HAITI. AT THE SFC...LOW PRES WAS LOCATED NEAR JAMES BAY WITH A COLD FRONT EXTENDING SOUTH THROUGH ERN UPR MI. CONVECTION FROM LAST EVENING ALONG THE FRONT HAS NOW EXITED EAST OF THE FCST AREA ALTHOUGH STRATUS CLOUDS LINGER IN COLDER AIR BEHIND THE FRONT EXTENDING FROM UPR MI BACK INTO NRN MN. && .DISCUSSION... BIG FCST CHALLENGE WILL BE DETERMINING CHC OF PCPN OVER THE FCST AREA LATE THU INTO FRI AS THE REMNANTS OF GUSTAV LIFT NORTH ALONG FRONTAL BOUNDARY OVER THE LOWER MIDWEST. TODAY...MUCH COLDER AIR WILL FLOOD OVER UPR GREAT LAKES IN THE WAKE OF THE FRONT. EXPECT MAX TEMPS TO RANGE FROM THE LOWER 60S NW TO LOWER 70S ALONG LAKE MI AS 850 MB TEMPS FALL INTO THE 4C-7C RANGE. SC DECK MAY REMAIN TRAPPED UNDER SUBSIDENCE INVERSION AT LEAST INTO EARLY AFTERNOON BUT THEN GRADUALLY SCOUR OUT WITH INCREASINGLY ANTICYCLONIC DIVERGENT LOW LEVEL FLOW FROM THE WEST. TONIGHT...MODELS NOW INDICATE THAT THE SFC HIGH PRES CENTER WILL STAY NW OF LAKE SUPERIOR KEEPING THE FCST AREA UNDER A GENERAL NE FLOW. MODEL SNDGS ALSO INDICATE THAT THERE COULD BE AN INCREASE IN HIGH CLOUDS AHEAD OF GUSTAV REMNANTS TOWARD THU MORNING. GIVEN THE COMBINATION OF SLIGHTLY MORE WIND AND POSSIBLE CLOUDS DECIDED TO REMOVE FOG AND FROST FROM THE FCST FOR THE OVERNIGHT HOURS AND BUMP UP TEMPS A DEGREE OF TWO. UPR 30S HOWEVER STILL POSSIBLE OVER THE TRADITIONAL COLD SPOTS OF THE WRN INTERIOR. THU...00Z GFS HAS NOW TRENDED MORE CLOSELY TO CONSISTENT ECMWF SOLN OF THE PAST FEW RUNS BRINGING REMNANTS OF GUSTAV NORTH ALONG FRONTAL BOUNDARY OVER THE LOWER MIDWEST THU INTO THU NIGHT. GENERALLY HAVE FOLLOWED THE MORE CONSISTENT ECMWF SOLN WHICH IS A BIT SLOWER IN BRINGING PCPN SHIELD NORTH INTO DRIER AIRMASS ASSOC WITH CANADIAN SFC HIGH. FARTHER WEST SOLN OF THE NAM APPEARS TO BE AN OUTLIER AND HAVE DISGARDED IT...ALTHOUGH IF RIDGING BECOMES MORE PROMINENT OVER THE WRN ATLANTIC AHEAD OF HANNA...A MORE WESTWARD SOLN MAY NOT BE COMPLETELY OUT OF THE QUESTION. THU WILL BE COOL AGAIN WITH CONTINUED NE FLOW AND THICKENING CLOUDS. LOOK FOR HIGHS ONLY IN THE LOW TO MID 60S. BROUGHT CHC POPS FOR SHOWERS INTO FAR SCNTRL ZONES WITH INCREASINGLY MOISTURE AND ISENTROPIC ASCENT NOTED ON 300K SFC. THU NIGHT AND FRI...BEST ISENTROPIC LIFT OCCURS OVER ERN HALF OF FCST AREA THU NIGHT AS SHORTWAVE AND ASSOC SFC LOW LIFT NORTHEAST INTO SW LOWER MI BY 12Z FRI. PUT IN LIKELY POPS FOR SHOWERS OVER FAR ERN UPR MI TAPERING TO LOW CHC POPS OVER NCNTRL COUNTIES ON THE FRINGE OF BEST LIFT. WEAK ISENTROPIC LIFT COULD RESULT IN SOME LINGERING SHOWERS OVER THE FAR ERN FCST AREA FRI MORNING SO KEPT IN SLIGHT CHC POPS THERE...BUT OTHERWISE EXPECT PARTIAL CLEARING FROM THE WEST IN THE WAKE OF THE SYSTEM. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... MVFR/VFR CIGS CONTINUE TO AFFECT BOTH TAF SITES THANKS TO NW WINDS AND LL MOISTURE. AFTER LOWER CLOUDS MIX OUT LATE THIS AFTERNOON...LOW CLOUDS SHOULD REAPPEAR AGAIN...PARTICULARLY AT SAW. WILL NEED TO MONITOR IF MORE THAN SCT IS NEEDED. AFTER 15Z...HIGH CLOUDS WILL THEN FILTER IN AHEAD OF THE NEXT LOW PRESSURE SYSTEM. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... WEST TO NW WINDS KICKED UP AS EXPECTED BEHIND THE COLD FRONT THAT MOVED ACROSS DURING THE NIGHT...WITH WINDS BTWN 20-30 KT. THESE STRONG WINDS SHOULD CONTINUE THROUGH THIS MRNG...THEN DIMINISH WEST TO EAST THIS AFTN INTO TONIGHT AS HIGH PRESSURE OVER THE NORTHERN PLAINS BUILDS NE INTO NRN ONTARIO. WINDS WILL SETTLE BELOW 20 KT ACROSS ALL OF LAKE SUPERIOR BY THU MRNG. THE HIGH PRESSURE AREA IS EXPETED TO REMAIN CENTERED OVER NORTHERN ONTARIO THROUGH FRI...WHILE THE REMNANTS OF GUSTAV MOVE ACROSS LOWER MI. NE WINDS BETWEEN THE TWO PRESSURE AREAS COULD APPROACH 20 KT ON WESTERN LAKE SUPERIOR THU EVNG AND ON ERN LAKE SUPERIOR ON FRI. AFTER FRI...WINDS WILL SETTLE BACK DOWN TO UNDER 20 KT. ONLY FEATURE OF NOTE IS A LOW PRESSURE TROUGH EXPECTED TO DROP SOUTH ACROSS LAKE SUPERIOR ON SUNDAY. IF A LOW MOVES UP ALONG THIS TROUGH...THE N TO NE WINDS ON LAKE SUPERIOR COULD INCREASE TO 25 KT LATE SUN. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/DISCUSSION...VOSS AVIATION...KF MARINE...AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 742 AM EDT WED SEP 3 2008 UPDATED AVIATION DISCUSSION FOR 12Z TAF ISSUANCE. .SYNOPSIS... WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL RIDGE OVER THE ERN GREAT LAKES INTO QUEBEC AND A TROF FROM MANITOBA INTO THE NRN PLAINS. THE REMNANTS OF TROPICAL STORM GUSTAV STILL CIRCULATING OVER THE TX/ARK BORDER WHILE TROPICAL STORM HANNA IS ORGANIZING NORTH OF HAITI. AT THE SFC...LOW PRES WAS LOCATED NEAR JAMES BAY WITH A COLD FRONT EXTENDING SOUTH THROUGH ERN UPR MI. CONVECTION FROM LAST EVENING ALONG THE FRONT HAS NOW EXITED EAST OF THE FCST AREA ALTHOUGH STRATUS CLOUDS LINGER IN COLDER AIR BEHIND THE FRONT EXTENDING FROM UPR MI BACK INTO NRN MN. && .DISCUSSION... BIG FCST CHALLENGE WILL BE DETERMINING CHC OF PCPN OVER THE FCST AREA LATE THU INTO FRI AS THE REMNANTS OF GUSTAV LIFT NORTH ALONG FRONTAL BOUNDARY OVER THE LOWER MIDWEST. TODAY...MUCH COLDER AIR WILL FLOOD OVER UPR GREAT LAKES IN THE WAKE OF THE FRONT. EXPECT MAX TEMPS TO RANGE FROM THE LOWER 60S NW TO LOWER 70S ALONG LAKE MI AS 850 MB TEMPS FALL INTO THE 4C-7C RANGE. SC DECK MAY REMAIN TRAPPED UNDER SUBSIDENCE INVERSION AT LEAST INTO EARLY AFTERNOON BUT THEN GRADUALLY SCOUR OUT WITH INCREASINGLY ANTICYCLONIC DIVERGENT LOW LEVEL FLOW FROM THE WEST. TONIGHT...MODELS NOW INDICATE THAT THE SFC HIGH PRES CENTER WILL STAY NW OF LAKE SUPERIOR KEEPING THE FCST AREA UNDER A GENERAL NE FLOW. MODEL SNDGS ALSO INDICATE THAT THERE COULD BE AN INCREASE IN HIGH CLOUDS AHEAD OF GUSTAV REMNANTS TOWARD THU MORNING. GIVEN THE COMBINATION OF SLIGHTLY MORE WIND AND POSSIBLE CLOUDS DECIDED TO REMOVE FOG AND FROST FROM THE FCST FOR THE OVERNIGHT HOURS AND BUMP UP TEMPS A DEGREE OF TWO. UPR 30S HOWEVER STILL POSSIBLE OVER THE TRADITIONAL COLD SPOTS OF THE WRN INTERIOR. THU...00Z GFS HAS NOW TRENDED MORE CLOSELY TO CONSISTENT ECMWF SOLN OF THE PAST FEW RUNS BRINGING REMNANTS OF GUSTAV NORTH ALONG FRONTAL BOUNDARY OVER THE LOWER MIDWEST THU INTO THU NIGHT. GENERALLY HAVE FOLLOWED THE MORE CONSISTENT ECMWF SOLN WHICH IS A BIT SLOWER IN BRINGING PCPN SHIELD NORTH INTO DRIER AIRMASS ASSOC WITH CANADIAN SFC HIGH. FARTHER WEST SOLN OF THE NAM APPEARS TO BE AN OUTLIER AND HAVE DISGARDED IT...ALTHOUGH IF RIDGING BECOMES MORE PROMINENT OVER THE WRN ATLANTIC AHEAD OF HANNA...A MORE WESTWARD SOLN MAY NOT BE COMPLETELY OUT OF THE QUESTION. THU WILL BE COOL AGAIN WITH CONTINUED NE FLOW AND THICKENING CLOUDS. LOOK FOR HIGHS ONLY IN THE LOW TO MID 60S. BROUGHT CHC POPS FOR SHOWERS INTO FAR SCNTRL ZONES WITH INCREASINGLY MOISTURE AND ISENTROPIC ASCENT NOTED ON 300K SFC. THU NIGHT AND FRI...BEST ISENTROPIC LIFT OCCURS OVER ERN HALF OF FCST AREA THU NIGHT AS SHORTWAVE AND ASSOC SFC LOW LIFT NORTHEAST INTO SW LOWER MI BY 12Z FRI. PUT IN LIKELY POPS FOR SHOWERS OVER FAR ERN UPR MI TAPERING TO LOW CHC POPS OVER NCNTRL COUNTIES ON THE FRINGE OF BEST LIFT. WEAK ISENTROPIC LIFT COULD RESULT IN SOME LINGERING SHOWERS OVER THE FAR ERN FCST AREA FRI MORNING SO KEPT IN SLIGHT CHC POPS THERE...BUT OTHERWISE EXPECT PARTIAL CLEARING FROM THE WEST IN THE WAKE OF THE SYSTEM. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... BATCH OF MVFR/VFR CIG CLOUDS OVER NRN MN...ASSOCIATED WITH TRAPPED LOW LEVEL MOISTURE...DISAPPEAR AS THEY CROSS LAKE SUPERIOR BUT THEN REAPPEAR OVER UPPER MI AND ARE CURRENTLY AFFECTING BOTH TAF SITES. LOOK FOR MVFR/VFR CIGS TO CONTINUE TO AFFECT BOTH TAF SITES THIS MRNG AS NW WINDS CONTINUE TO BRING IN THE LOW LEVEL MOISTURE OUT OF NRN MN. DAYTIME HEATING SHOULD BE ABLE TO BRING CIGS TO VFR...AND LIKELY SCT OR CLEAR THE CLOUDS OUT THROUGH THE AFTN...ESPECIALLY AT CMX WITH LAKE STABILIZATION AIDING IN THE PROCESS. TONIGHT...AM UNCERTAIN IF LOW CLOUDS WILL REAPPEAR AGAIN...ESPECIALLY WITH A NE WIND DEVELOPING AND INLAND AREAS COOLING OFF. GREATEST CONCERN WOULD BE AT SAW SINCE NE WINDS UPSLOPE. FOR NOW HAVE HINTED AT THIS POSSIBILITY WITH A SCT DECK...BUT LATER FCSTS WILL HAVE TO WATCH. OTHER CONCERN IS THE GUSTY WINDS AT CMX. WINDS ARE EXPECTED TO REMAIN GUSTY THERE THROUGH EARLY AFTN...DUE TO FUNNELING FLOW AND MORE UNSTABLE CONDITIONS IN COLD ADVECTION REGIME. HIGH PRESSURE BUILDING IN LATE WILL DIMINISH THE WINDS. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... WEST TO NW WINDS KICKED UP AS EXPECTED BEHIND THE COLD FRONT THAT MOVED ACROSS DURING THE NIGHT...WITH WINDS BTWN 20-30 KT. THESE STRONG WINDS SHOULD CONTINUE THROUGH THIS MRNG...THEN DIMINISH WEST TO EAST THIS AFTN INTO TONIGHT AS HIGH PRESSURE OVER THE NORTHERN PLAINS BUILDS NE INTO NRN ONTARIO. WINDS WILL SETTLE BELOW 20 KT ACROSS ALL OF LAKE SUPERIOR BY THU MRNG. THE HIGH PRESSURE AREA IS EXPETED TO REMAIN CENTERED OVER NORTHERN ONTARIO THROUGH FRI...WHILE THE REMNANTS OF GUSTAV MOVE ACROSS LOWER MI. NE WINDS BETWEEN THE TWO PRESSURE AREAS COULD APPROACH 20 KT ON WESTERN LAKE SUPERIOR THU EVNG AND ON ERN LAKE SUPERIOR ON FRI. AFTER FRI...WINDS WILL SETTLE BACK DOWN TO UNDER 20 KT. ONLY FEATURE OF NOTE IS A LOW PRESSURE TROUGH EXPECTED TO DROP SOUTH ACROSS LAKE SUPERIOR ON SUNDAY. IF A LOW MOVES UP ALONG THIS TROUGH...THE N TO NE WINDS ON LAKE SUPERIOR COULD INCREASE TO 25 KT LATE SUN. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/DISCUSSION...VOSS AVIATION...AJ MARINE...AJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 439 AM EDT WED SEP 3 2008 .SYNOPSIS... WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL RIDGE OVER THE ERN GREAT LAKES INTO QUEBEC AND A TROF FROM MANITOBA INTO THE NRN PLAINS. THE REMNANTS OF TROPICAL STORM GUSTAV STILL CIRCULATING OVER THE TX/ARK BORDER WHILE TROPICAL STORM HANNA IS ORGANIZING NORTH OF HAITI. AT THE SFC...LOW PRES WAS LOCATED NEAR JAMES BAY WITH A COLD FRONT EXTENDING SOUTH THROUGH ERN UPR MI. CONVECTION FROM LAST EVENING ALONG THE FRONT HAS NOW EXITED EAST OF THE FCST AREA ALTHOUGH STRATUS CLOUDS LINGER IN COLDER AIR BEHIND THE FRONT EXTENDING FROM UPR MI BACK INTO NRN MN. && .DISCUSSION... BIG FCST CHALLENGE WILL BE DETERMINING CHC OF PCPN OVER THE FCST AREA LATE THU INTO FRI AS THE REMNANTS OF GUSTAV LIFT NORTH ALONG FRONTAL BOUNDARY OVER THE LOWER MIDWEST. TODAY...MUCH COLDER AIR WILL FLOOD OVER UPR GREAT LAKES IN THE WAKE OF THE FRONT. EXPECT MAX TEMPS TO RANGE FROM THE LOWER 60S NW TO LOWER 70S ALONG LAKE MI AS 850 MB TEMPS FALL INTO THE 4C-7C RANGE. SC DECK MAY REMAIN TRAPPED UNDER SUBSIDENCE INVERSION AT LEAST INTO EARLY AFTERNOON BUT THEN GRADUALLY SCOUR OUT WITH INCREASINGLY ANTICYCLONIC DIVERGENT LOW LEVEL FLOW FROM THE WEST. TONIGHT...MODELS NOW INDICATE THAT THE SFC HIGH PRES CENTER WILL STAY NW OF LAKE SUPERIOR KEEPING THE FCST AREA UNDER A GENERAL NE FLOW. MODEL SNDGS ALSO INDICATE THAT THERE COULD BE AN INCREASE IN HIGH CLOUDS AHEAD OF GUSTAV REMNANTS TOWARD THU MORNING. GIVEN THE COMBINATION OF SLIGHTLY MORE WIND AND POSSIBLE CLOUDS DECIDED TO REMOVE FOG AND FROST FROM THE FCST FOR THE OVERNIGHT HOURS AND BUMP UP TEMPS A DEGREE OF TWO. UPR 30S HOWEVER STILL POSSIBLE OVER THE TRADITIONAL COLD SPOTS OF THE WRN INTERIOR. THU...00Z GFS HAS NOW TRENDED MORE CLOSELY TO CONSISTENT ECMWF SOLN OF THE PAST FEW RUNS BRINGING REMNANTS OF GUSTAV NORTH ALONG FRONTAL BOUNDARY OVER THE LOWER MIDWEST THU INTO THU NIGHT. GENERALLY HAVE FOLLOWED THE MORE CONSISTENT ECMWF SOLN WHICH IS A BIT SLOWER IN BRINGING PCPN SHIELD NORTH INTO DRIER AIRMASS ASSOC WITH CANADIAN SFC HIGH. FARTHER WEST SOLN OF THE NAM APPEARS TO BE AN OUTLIER AND HAVE DISGARDED IT...ALTHOUGH IF RIDGING BECOMES MORE PROMINENT OVER THE WRN ATLANTIC AHEAD OF HANNA...A MORE WESTWARD SOLN MAY NOT BE COMPLETELY OUT OF THE QUESTION. THU WILL BE COOL AGAIN WITH CONTINUED NE FLOW AND THICKENING CLOUDS. LOOK FOR HIGHS ONLY IN THE LOW TO MID 60S. BROUGHT CHC POPS FOR SHOWERS INTO FAR SCNTRL ZONES WITH INCREASINGLY MOISTURE AND ISENTROPIC ASCENT NOTED ON 300K SFC. THU NIGHT AND FRI...BEST ISENTROPIC LIFT OCCURS OVER ERN HALF OF FCST AREA THU NIGHT AS SHORTWAVE AND ASSOC SFC LOW LIFT NORTHEAST INTO SW LOWER MI BY 12Z FRI. PUT IN LIKELY POPS FOR SHOWERS OVER FAR ERN UPR MI TAPERING TO LOW CHC POPS OVER NCNTRL COUNTIES ON THE FRINGE OF BEST LIFT. WEAK ISENTROPIC LIFT COULD RESULT IN SOME LINGERING SHOWERS OVER THE FAR ERN FCST AREA FRI MORNING SO KEPT IN SLIGHT CHC POPS THERE...BUT OTHERWISE EXPECT PARTIAL CLEARING FROM THE WEST IN THE WAKE OF THE SYSTEM. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... SKIES HAVE CLEARED OUT AT CMX...BUT MVFR TO VFR CIGS STILL EXIST AT SAW. CIGS AT SAW SHOULD COME UP TO VFR WITHIN THE NEXT TWO HOURS AS CLEARING MOVES IN THERE. NEXT CONCERN IS MVFR CLOUDS SEEN OVER NRN MN. SOME OF THIS MAY MAKE IT INTO THE TAF SITES LATER THIS MRNG...BUT CONFIDENCE IS ONLY HIGH ENOUGH TO INCLUDE A TEMPO RATHER THAN GOING PREDOMINANT. THESE CLOUDS WILL CLEAR OUT AT CMX AS LAKE STABILIZATION COMES INTO PLAY LATER THIS AFTN. CLOUDS MAY HANG AROUND SAW THROUGH THE AFTN...BUT LIKELY MIXING OUT THROUGH THE AFTN AND CLIMBING TO VFR...ASSUMING THAT MVFR CLOUDS DEVELOPED IN THE MRNG. SKIES WILL THEN REMAIN VFR AT BOTH TAF SITES THROUGH THE REST OF THE PERIOD. OTHER CONCERN IS THE GUSTY WINDS AT CMX. WINDS ARE EXPECTED TO REMAIN GUSTY THERE THROUGH EARLY AFTN...DUE TO FUNNELING FLOW AND MORE UNSTABLE CONDITIONS IN COLD ADVECTION REGIME. HIGH PRESSURE BUILDING IN LATE WILL DIMINISH THE WINDS. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... WEST TO NW WINDS KICKED UP AS EXPECTED BEHIND THE COLD FRONT THAT MOVED ACROSS DURING THE NIGHT...WITH WINDS BTWN 20-30 KT. THESE STRONG WINDS SHOULD CONTINUE THROUGH THIS MRNG...THEN DIMINISH WEST TO EAST THIS AFTN INTO TONIGHT AS HIGH PRESSURE OVER THE NORTHERN PLAINS BUILDS NE INTO NRN ONTARIO. WINDS WILL SETTLE BELOW 20 KT ACROSS ALL OF LAKE SUPERIOR BY THU MRNG. THE HIGH PRESSURE AREA IS EXPETED TO REMAIN CENTERED OVER NORTHERN ONTARIO THROUGH FRI...WHILE THE REMNANTS OF GUSTAV MOVE ACROSS LOWER MI. NE WINDS BETWEEN THE TWO PRESSURE AREAS COULD APPROACH 20 KT ON WESTERN LAKE SUPERIOR THU EVNG AND ON ERN LAKE SUPERIOR ON FRI. AFTER FRI...WINDS WILL SETTLE BACK DOWN TO UNDER 20 KT. ONLY FEATURE OF NOTE IS A LOW PRESSURE TROUGH EXPECTED TO DROP SOUTH ACROSS LAKE SUPERIOR ON SUNDAY. IF A LOW MOVES UP ALONG THIS TROUGH...THE N TO NE WINDS ON LAKE SUPERIOR COULD INCREASE TO 25 KT LATE SUN. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/DISCUSSION...VOSS AVIATION...AJ MARINE...AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 139 AM EDT WED SEP 3 2008 UPDATED AVIATION DISCUSSION FOR 06Z TAF ISSUANCE .SYNOPSIS... WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL RIDGE OVER THE ERN GREAT LAKES INTO QUEBEC AND TROF FROM MANITOBA INTO THE NRN PLAINS RESULTING IN SW FLOW THROUGH THE UPPER MS VALLEY AND WRN LAKES. AT THE SFC...LOW PRES WAS LOCATED OVER NRN ONTARIO (VCNTY CYPL) WITH A COLD FRONT TO THE SOUTH THROUGH NE MN AND WRN WI. SCT/ISOLD SHRA/TSRA HAVE DEVELOPED AHEAD OF THE FRONT ACRS WRN UPPER MI IN AREA WITH MLCAPE VALUES IN THE 1000-1500 J/KG WHERE CAP HAS WEAKENED. MORE NMRS SHRA/TSRA WERE MOVING THROUGH NW WI JUST AHEAD OF THE FRONT IN AREA OF 900-800 MB FGEN. && .SHORT TERM...(TONIGHT AND WEDNESDAY) EXPECT THE BAND OF SCT/NMRS SHRA/TSRA TO PUSH ACROSS UPPER MI TONIGHT AS THE FRONT MOVES THROUGH THE AREA. SO...GOING LIKELY POPS STILL LOOK ON TRACK EVEN THOUGH AREAS OF HEAVIER RAIN (GREATER THAN A HALF INCH) MAY BE FAIRLY ISOLATED. SOME WIND GUSTS NEAR SEVERE VALUES MAY STILL BE POSSIBLE IF LINE SEGMENT OF TSTMS DEVELOP PERPENDICULAR TO THE MEAN WIND AS WAS OBSERVED THROUGH NW WI EARLIER THIS AFTERNOON. MUCH COOLER WEATHER WILL PREVAIL ON WEDNESDAY WITH MAX TEMPS IN THE 60S AS 850 MB TEMPS FALL INTO THE 5C-8C RANGE COMPARED TO VALUES NEAR 19C TODAY. EVEN THOUGH THERE IS EXTENSIVE LOW CLOUDS OVER ND AND MN BEHIND THE FRONT...THE NAM REMAINS CONSISTENT IN MOVING THE LOW LEVEL MOISTURE MAINLY TO THE NE WITH ACYC DIVERGENT LOW LEVEL FLOW LIKELY KEEPING SCT CU/SC OVER UPPER MI. .LONG TERM (WEDNESDAY NIGHT THROUGH TUESDAY)... FEW CHANGES WERE MADE TO THE ONGOING FORECAST...POSSIBILITY OF PATCHY FOG AND/OR FROST WEDNESDAY NIGHT AND FOG THURSDAY NIGHT. MUCH OF THE AREA WILL REMAIN UNDER THE INFLUENCE OF A 500 MB TROUGH. THE MAIN QUESTION FOR THIS PERIOD WILL BE HOW FAR NORTH THE INFLUX OF MOISTURE WILL MAKE IT THURSDAY NIGHT AND FRIDAY. THE REMNANTS OF GUSTAV WILL COMBINE WITH THE COLD FRONT CURRENTLY OVER THE TRI-STATE REGION. IT IS EXPECTED TO WEAKEN SIGNIFICANTLY AS IT SLIDES NORTH ALONG THE FRONT AND TO INDIANA BY 12Z FRIDAY. FORECAST WISE...HAVE OPTED FOR A CONTINUED SOUTHERN TRACK TO THIS FEATURE...KEEPING MUCH OF UPPER MICHIGAN DRY. YET ANOTHER COLD FRONT WILL BE POISED TO MAKE A CROSSING OVER LAKE SUPERIOR AND UPPER MICHIGAN FOR THE END OF THE UPCOMING WEEKEND. AS A RESULT...IT WILL BE HARD TO RULE OUT A CHANCE OF SLIGHT CHANCE OF PRECIPITATION SATURDAY THROUGH TUESDAY. HAVE GONE VERY CLOSE TO HPC GUIDANCE FOR DAYS 4/SATURDAY THROUGH 7/TUESDAY. THIS WAS MAINLY THE ECMWF. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... SKIES HAVE CLEARED OUT AT CMX...BUT MVFR TO VFR CIGS STILL EXIST AT SAW. CIGS AT SAW SHOULD COME UP TO VFR WITHIN THE NEXT TWO HOURS AS CLEARING MOVES IN THERE. NEXT CONCERN IS MVFR CLOUDS SEEN OVER NRN MN. SOME OF THIS MAY MAKE IT INTO THE TAF SITES LATER THIS MRNG...BUT CONFIDENCE IS ONLY HIGH ENOUGH TO INCLUDE A TEMPO RATHER THAN GOING PREDOMINANT. THESE CLOUDS WILL CLEAR OUT AT CMX AS LAKE STABILIZATION COMES INTO PLAY LATER THIS AFTN. CLOUDS MAY HANG AROUND SAW THROUGH THE AFTN...BUT LIKELY MIXING OUT THROUGH THE AFTN AND CLIMBING TO VFR...ASSUMING THAT MVFR CLOUDS DEVELOPED IN THE MRNG. SKIES WILL THEN REMAIN VFR AT BOTH TAF SITES THROUGH THE REST OF THE PERIOD. OTHER CONCERN IS THE GUSTY WINDS AT CMX. WINDS ARE EXPECTED TO REMAIN GUSTY THERE THROUGH EARLY AFTN...DUE TO FUNNELING FLOW AND MORE UNSTABLE CONDITIONS IN COLD ADVECTION REGIME. HIGH PRESSURE BUILDING IN LATE WILL DIMINISH THE WINDS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... SOUTH TO SOUTHWEST WINDS OF 15 TO 25 KT WILL SHIFT ABRUPTLY WEST AND GUST TO 30 KT AT TIMES TONIGHT BEHIND A COLD FRONTAL PASSAGE. INCREASINGLY UNSTABLE CONDITIONS COULD ALLOW WAVES TO BRIEFLY BUILD TO 4 TO 7 FEET LATE TONIGHT AND WEDNESDAY. WINDS WILL DIE OFF WELL BLO 20 KT LATE WED NIGHT AND GENERALLY STAY THAT WAY INTO SATURDAY AS HIGH PRESSURE BECOMES ENTRENCHED OVER THE REGION. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ SHORT TERM...JLB LONG TERM...KF AVIATION...AJ MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 1034 AM CDT WED SEP 3 2008 .UPDATE...FORECAST IN GREAT SHAPE FOR TODAY. MADE MINOR ADJUSTMENTS TO CLOUD COVER AND TEMPERATURES. STRATOCU DECK HAS SHIFT SOUTH ACROSS THE ARROWHEAD...TWIN PORTS AND ALONG THE SOUTH SHORE...WHILE DIURNAL CU CONTINUES TO DEVELOP ELSEWHERE. EXPECTED SCT TO BKN COVERAGE TO CONTINUE THROUGH THIS AFTERNOON. && .PREV DISCUSSION... /ISSUED 343 AM CDT WED SEP 3 2008/ DISCUSSION... CURRENT SURFACE ANALYSIS DEPICTS A SURFACE TROUGH AND COLD FRONT PUSHING TO THE EAST ACROSS MICHIGAN. MEANWHILE...ITS UPPER LOW IS SLUGGISHLY DRIFTING EAST-NORTHEAST ACROSS ONTARIO. THIS FEATURE HAS WORKED TO KEEP LOW CLOUDS AND EVEN SOME SCATTERED SPRINKLES OVER MUCH OF NE MN THROUGH EARLY THIS MORNING. HIGH PRESSURE WAS BUILDING TO OUR SOUTHWEST...OVER NEBRASKA AND SOUTH DAKOTA. THE NAM12 AND RUC40 SUGGEST THAT SCT-BKN LOW CLOUDS...MAINLY STRATOCU...WILL REMAIN IN PLACE THROUGH THIS MORNING...ESPECIALLY FROM THE BORDERLAND AND INTO THE ARROWHEAD...BEFORE DECREASING AFTER 18Z AS DRIER LOW-MID LEVEL AIR IS ADVECTED INTO THE REGION AS HIGH PRESSURE PUSHES INTO MINNESOTA. MEANWHILE...SOME HIGH AND MID LEVEL CLOUDS MAY AFFECT THE SOUTHEAST PORTION OF AREA THIS MORNING. WATER VAPOR IMAGERY SUGGESTS THAT DRIER AIR CURRENTLY WORKING INTO WESTERN MINNESOTA HAS MADE LITTLE PROGRESS EASTWARD DURING THE PAST FEW HOURS. TEMPERATURES TODAY WILL BE CONSIDERABLY COOLER...WITH MAXES GENERALLY IN THE 60S. 85H TEMPS OF 2-4C AT 12Z TODAY WILL ONLY WARM TO 3C-6C THIS AFTERNOON. WITH THE COOLER TEMPS ALOFT...EXPECTING A GOOD AMOUNT OF CUMULUS TO DEVELOP WITH DAYTIME HEATING...WITH THE NAM12 CU RULE PAINTING VALUES OF -2 TO -3 OVER PORTIONS OF NE MINNESOTA THIS AFTERNOON. AS HIGH PRESSURE SETTLES OVERHEAD TONIGHT...TEMPERATURES COULD GET QUITE COOL IN THE FAVORED LOCATIONS...ESPECIALLY IN THE ARROWHEAD. HOWEVER...THE POSITION OF THE HIGH WILL ALSO FAVOR A NORTHEAST FLOW...WHICH COULD ENHANCE LOW CLOUDS AND THE POTENTIAL FOR FOG...ESPECIALLY NEAR AND ALONG THE LAKE. AREAS THAT REMAIN RELATIVELY CLOUD FREE COULD BOTTOM OUT IN THE MID 30S. HAVE MENTIONED AREAS OF FROST TO PORTIONS OF THE BORDERLAND AND ARROWHEAD FOR THE OVERNIGHT. FOR THURSDAY...A SHORTWAVE WILL PUSH EAST INTO THE DAKOTAS. THIS FEATURE WILL BRING SOME INCREASE IN HIGH AND MID LEVEL CLOUDS TO OUR WESTERN ZONES...WHILE THE REMNANTS OF TS GUSTAV ADVANCE NORTH INTO IOWA. HAVE ACCORDINGLY INCREASED SKY COVER FOR THURSDAY AFTERNOON FOR OUR NW WISCONSIN ZONES. WHILE THE ECMWF AND GFS SKIRT OUR FAR SOUTHEAST ZONES WITH SOME LIGHT QPF THURSDAY NIGHT INTO FRIDAY...THEY CONTINUE TO KEEP THE BULK OF THE MOISTURE TO THE SOUTHEAST. EVEN THE LATEST NAM HAS BACKED OFF WITH ITS NORTHWEST EXTENT OF QPF. WE HAVE INTRODUCED SILENT POPS FOR THURSDAY AFTERNOON AND NIGHT...BUT BELIEVE MUCH...IF NOT ALL...OF THIS MOISTURE WILL STAY JUST SOUTHEAST OF OUR CWA. GIVEN SOME MODEST WARM AIR ADVECTION...TEMPERATURES ON THURSDAY WILL BE A FEW DEGREES WARMER. HOWEVER...WITH ONSHORE FLOW...TEMPERATURES COULD BE QUITE CHILLY NEAR THE LAKE. BUMPED TEMPERATURES DOWN SLIGHTLY...ESPECIALLY ALONG THE NORTH SHORE...BUT ADDITIONAL ADJUSTMENTS MAY BE NEEDED. THE AFOREMENTIONED SHORTWAVE WILL PUSH EAST INTO OUR AREA LATE THURSDAY NIGHT AND FRIDAY...BRINGING A CHANCE FOR SCATTERED RAIN SHOWERS AND THUNDERSTORMS. ALL MODELS SUGGEST THAT THE BEST DYNAMICS AND FORCING WILL REMAIN TO OUR NORTH AND WEST...SO NOT EXPECTING ANY WIDESPREAD SIGNIFICANT RAINFALL...WITH THE HIGHEST POPS IN OUR NW ZONES. INSTABILITY PARAMETERS ARE ALSO RATHER WEAK...WITH MINIMAL CAPE AND LIFTED INDEX VALUES ONLY APPROACHING ZERO...SO THE CHANCE FOR STRONG STORMS SEEMS QUITE REMOTE. A LARGE TROUGH WILL THEN REMAIN IN PLACE FROM THE HIGH PLAINS TO UPPER MIDWEST THROUGH THE WEEKEND...BRINGING PERIODIC CHANCES OF SHOWERS AND THUNDERSTORMS...ALTHOUGH THE TIMING OF INDIVIDUAL SHORTWAVES REMAINS UNCERTAIN AT THIS POINT. AVIATION... LOW VFR CEILINGS COVERED PARTS OF NORTHERN MINNESOTA...WITH AREAS OF MVFR CEILINGS. CLOUDS WERE MAINLY SCATTERED OVER NORTHWEST WISCONSIN. EXPECT THE CLOUDS TO GRADUALLY LIFT AND DECREASE IN COVERAGE THROUGH THE DAY TODAY. HIGH PRESSURE WILL BE BUILDING INTO THE REGION AND HELP BREAK UP THE CLOUDS. TEMPERATURES ALOFT ARE COLD...SO EXPECT CUMULUS TO RE-DEVELOP LATE THIS MORNING AND AFTERNOON...AND A PERIOD OR TWO OF BROKEN CEILINGS WILL BE POSSIBLE...ESPECIALLY IN FAR NORTHERN MINNESOTA. PATCHY FOG WILL BE POSSIBLE TONIGHT...ESPECIALLY AROUND LAKE SUPERIOR. && POINT TEMPS/POPS... DLH 64 43 62 45 / 10 0 10 10 INL 63 39 67 43 / 10 0 10 20 BRD 65 43 70 45 / 10 0 10 10 HYR 68 38 67 43 / 10 0 10 10 ASX 63 41 65 44 / 10 0 10 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...SMALL CRAFT ADVISORY UNTIL 1 PM CDT THIS AFTERNOON FOR LSZ121- LSZ146-LSZ147-LSZ148. $$ LILES mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 343 AM CDT WED SEP 3 2008 .DISCUSSION... CURRENT SURFACE ANALYSIS DEPICTS A SURFACE TROUGH AND COLD FRONT PUSHING TO THE EAST ACROSS MICHIGAN. MEANWHILE...ITS UPPER LOW IS SLUGGISHLY DRIFTING EAST-NORTHEAST ACROSS ONTARIO. THIS FEATURE HAS WORKED TO KEEP LOW CLOUDS AND EVEN SOME SCATTERED SPRINKLES OVER MUCH OF NE MN THROUGH EARLY THIS MORNING. HIGH PRESSURE WAS BUILDING TO OUR SOUTHWEST...OVER NEBRASKA AND SOUTH DAKOTA. THE NAM12 AND RUC40 SUGGEST THAT SCT-BKN LOW CLOUDS...MAINLY STRATOCU...WILL REMAIN IN PLACE THROUGH THIS MORNING...ESPECIALLY FROM THE BORDERLAND AND INTO THE ARROWHEAD...BEFORE DECREASING AFTER 18Z AS DRIER LOW-MID LEVEL AIR IS ADVECTED INTO THE REGION AS HIGH PRESSURE PUSHES INTO MINNESOTA. MEANWHILE...SOME HIGH AND MID LEVEL CLOUDS MAY AFFECT THE SOUTHEAST PORTION OF AREA THIS MORNING. WATER VAPOR IMAGERY SUGGESTS THAT DRIER AIR CURRENTLY WORKING INTO WESTERN MINNESOTA HAS MADE LITTLE PROGRESS EASTWARD DURING THE PAST FEW HOURS. TEMPERATURES TODAY WILL BE CONSIDERABLY COOLER...WITH MAXES GENERALLY IN THE 60S. 85H TEMPS OF 2-4C AT 12Z TODAY WILL ONLY WARM TO 3C-6C THIS AFTERNOON. WITH THE COOLER TEMPS ALOFT...EXPECTING A GOOD AMOUNT OF CUMULUS TO DEVELOP WITH DAYTIME HEATING...WITH THE NAM12 CU RULE PAINTING VALUES OF -2 TO -3 OVER PORTIONS OF NE MINNESOTA THIS AFTERNOON. AS HIGH PRESSURE SETTLES OVERHEAD TONIGHT...TEMPERATURES COULD GET QUITE COOL IN THE FAVORED LOCATIONS...ESPECIALLY IN THE ARROWHEAD. HOWEVER...THE POSITION OF THE HIGH WILL ALSO FAVOR A NORTHEAST FLOW...WHICH COULD ENHANCE LOW CLOUDS AND THE POTENTIAL FOR FOG...ESPECIALLY NEAR AND ALONG THE LAKE. AREAS THAT REMAIN RELATIVELY CLOUD FREE COULD BOTTOM OUT IN THE MID 30S. HAVE MENTIONED AREAS OF FROST TO PORTIONS OF THE BORDERLAND AND ARROWHEAD FOR THE OVERNIGHT. FOR THURSDAY...A SHORTWAVE WILL PUSH EAST INTO THE DAKOTAS. THIS FEATURE WILL BRING SOME INCREASE IN HIGH AND MID LEVEL CLOUDS TO OUR WESTERN ZONES...WHILE THE REMNANTS OF TS GUSTAV ADVANCE NORTH INTO IOWA. HAVE ACCORDINGLY INCREASED SKY COVER FOR THURSDAY AFTERNOON FOR OUR NW WISCONSIN ZONES. WHILE THE ECMWF AND GFS SKIRT OUR FAR SOUTHEAST ZONES WITH SOME LIGHT QPF THURSDAY NIGHT INTO FRIDAY...THEY CONTINUE TO KEEP THE BULK OF THE MOISTURE TO THE SOUTHEAST. EVEN THE LATEST NAM HAS BACKED OFF WITH ITS NORTHWEST EXTENT OF QPF. WE HAVE INTRODUCED SILENT POPS FOR THURSDAY AFTERNOON AND NIGHT...BUT BELIEVE MUCH...IF NOT ALL...OF THIS MOISTURE WILL STAY JUST SOUTHEAST OF OUR CWA. GIVEN SOME MODEST WARM AIR ADVECTION...TEMPERATURES ON THURSDAY WILL BE A FEW DEGREES WARMER. HOWEVER...WITH ONSHORE FLOW...TEMPERATURES COULD BE QUITE CHILLY NEAR THE LAKE. BUMPED TEMPERATURES DOWN SLIGHTLY...ESPECIALLY ALONG THE NORTH SHORE...BUT ADDITIONAL ADJUSTMENTS MAY BE NEEDED. THE AFOREMENTIONED SHORTWAVE WILL PUSH EAST INTO OUR AREA LATE THURSDAY NIGHT AND FRIDAY...BRINGING A CHANCE FOR SCATTERED RAIN SHOWERS AND THUNDERSTORMS. ALL MODELS SUGGEST THAT THE BEST DYNAMICS AND FORCING WILL REMAIN TO OUR NORTH AND WEST...SO NOT EXPECTING ANY WIDESPREAD SIGNIFICANT RAINFALL...WITH THE HIGHEST POPS IN OUR NW ZONES. INSTABILITY PARAMETERS ARE ALSO RATHER WEAK...WITH MINIMAL CAPE AND LIFTED INDEX VALUES ONLY APPROACHING ZERO...SO THE CHANCE FOR STRONG STORMS SEEMS QUITE REMOTE. A LARGE TROUGH WILL THEN REMAIN IN PLACE FROM THE HIGH PLAINS TO UPPER MIDWEST THROUGH THE WEEKEND...BRINGING PERIODIC CHANCES OF SHOWERS AND THUNDERSTORMS...ALTHOUGH THE TIMING OF INDIVIDUAL SHORTWAVES REMAINS UNCERTAIN AT THIS POINT. && .AVIATION... LOW VFR CEILINGS COVERED PARTS OF NORTHERN MINNESOTA...WITH AREAS OF MVFR CEILINGS. CLOUDS WERE MAINLY SCATTERED OVER NORTHWEST WISCONSIN. EXPECT THE CLOUDS TO GRADUALLY LIFT AND DECREASE IN COVERAGE THROUGH THE DAY TODAY. HIGH PRESSURE WILL BE BUILDING INTO THE REGION AND HELP BREAK UP THE CLOUDS. TEMPERATURES ALOFT ARE COLD...SO EXPECT CUMULUS TO RE-DEVELOP LATE THIS MORNING AND AFTERNOON...AND A PERIOD OR TWO OF BROKEN CEILINGS WILL BE POSSIBLE...ESPECIALLY IN FAR NORTHERN MINNESOTA. PATCHY FOG WILL BE POSSIBLE TONIGHT...ESPECIALLY AROUND LAKE SUPERIOR. && POINT TEMPS/POPS... DLH 65 43 62 45 / 0 0 10 10 INL 63 39 67 43 / 10 0 10 20 BRD 66 43 70 45 / 0 0 10 10 HYR 67 38 67 43 / 0 0 10 10 ASX 63 41 65 44 / 10 0 10 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...SMALL CRAFT ADVISORY UNTIL 1 PM CDT THIS AFTERNOON FOR LSZ121- LSZ146-LSZ147-LSZ148. $$ BETTWY/MELDE mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 1230 PM CDT THU SEP 4 2008 .UPDATE...SATELLITE IMAGERY/RUC ANALYSIS SHOWS THE CENTER OF THE REMNANTS OF GUSTAV MOVING NNE INTO CENTRAL MISSOURI. CIRCULATION AROUND THIS CENTER HAS BROUGHT COOLER AND DRIER AIR INTO OUR WESTERN ZONES. A DRY SLOT WAS NOTED ON SATELLITE IMAGERY GENERALLY OVER THE MISSISSIPPI RIVER. THE BAND OF SHOWERS AND THUNDERSTORMS THAT MOVED OVER OUR CWFA LAST NIGHT WAS BROKEN AND NEARLY STALLED OVER EASTERN MISSISSIPPI. THE FLASH FLOOD WATCH FOR OUR SOUTHEAST COUNTIES THIS AFTERNOON WILL REMAIN IN EFFECT AS TRAINING STORMS WILL HAVE THE POTENTIAL TO PRODUCE SOME FLOODING. HAVE UPDATED FORECAST THOUGH TO LOWER POPS OVER THE WESTERN TWO-THIRDS OF THE CWFA THIS AFTERNOON. SOME VERY LIGHT RAIN AND DRIZZLE WAS BEING OBSERVED IN ARKANSAS AND MAY OCCUR OVER OUR SOUTHEAST ARKANSAS AND NORTHWEST MISSISSIPPI COUNTIES. OUR PARISHES AND WEST CENTRAL MISSISSIPPI COUNTIES SHOULD NOT SEE ANY ADDITIONAL PRECIPITATION TODAY. ALTHOUGH CAN`T RULE OUT A TORNADO IN THE EAST THIS AFTERNOON BUT THE SHEAR IS MUCH WEAKER TODAY. REMAINDER OF FORECAST LOOKED OK. UPDATES HAVE BEEN POSTED. /22/ .PREVIOUS DISCUSSION...SHORT TERM(TODAY THROUGH FRIDAY)...THERE FINALLY APPEARS TO BE LIGHT AT THE END OF THE GUSTAV TUNNEL THIS MORNING. SOME INCREDIBLE RAINFALL TOTALS ABOVE 20 INCHES WILL BE PUBLISHED LATER THIS MORNING AS THEY BECOME AVAILABLE. LATEST SATELLITE IMAGERY/SURFACE ANALYSIS SHOWS REMNANTS OF GUSTAV ACROSS CENTRAL ARKANSAS MOVING NNE. LAST CONVECTIVE BAND ROUGHLY ALONG INTERSTATE 55 CREEPING STEADILY EWD THIS MORNING WITH DECREASING RAINFALL RATES OF GENERALLY ABOUT 1 INCH/HOUR OR LESS. RISING SURFACE PRESSURES AND WEAKENING LOW LEVEL WINDS APPEAR TO BE LIMITING THE INTENSITY OF THE BAND. AS FAR AS FLASH FLOOD POTENTIAL...ONGOING FLOODING DICTATES THAT WE NOT CANCEL THE FFA UNTIL RAIN COMPLETELY GONE. WE WILL LET THE FLASH FLOOD WATCH EXPIRE FOR MOST AREAS THIS MORNING BUT EXTEND IT FOR SERN/SCNTRL AREAS THROUGH THE AFTERNOON. THE REMNANTS OF THE RAIN BAND WILL MOVE THROUGH ERN ZONES TODAY. RAIN PROCESSES WILL BECOME MORE OF A HYBRID BETWEEN TROPICAL AND CONVECTIVE AND MID 70S DEWPOINTS MAY HELP ENHANCE THUNDERSTORM DEVELOPMENT ALONG AND AHEAD OF THE RAIN BAND TODAY. SHORT RANGE NAM12/RUC SHOW THAT THE REMNANTS OF GUSTAV PUSH AWAY ACROSS SOUTHERN MISSOURI THIS MORNING AND INTO SRN ILLINOIS TONIGHT. THIS SHOULD DIMINISH THE HEAVY RAIN POTENTIAL BY TONIGHT ALTHOUGH A WEAK SURFACE TROUGH/BOUNDARY WILL BE TRAILING INTO ERN MS. AFTERNOON MLCAPES PROGGED TO REACH 1200-1600J/KG OVER AT LEAST SERN HALF OF CWFA WITH K INDEXES HOLDING IN THE M30S. DECENT FORWARD CELL MOTIONS SHOULD LIMIT RAIN VOLUMES HOPEFULLY. LOOK FOR THE WEAK CONVERGENT AXIS TO EXIT TO THE E LATER THIS EVENING. THE ARKLAMISS SHOULD DRY OUT FROM THE WEST LATER FRIDAY WITH MORE ABUNDANT SUNSHINE TO HELP IN EVAPORATION. AS FAR AS TEMPS ARE CONCERNED BELIEVE THAT SOGGY GROUND WILL LIMIT WARMING FOR TODAY WHILE EXPECT NEAR CLIMATOLOGY HIGHS MORE PROBABLE ON FRIDAY SO MADE SOME SLIGHT UPWARD ADJUSTMENTS TO GUIDANCE. OVERNIGHT LOWS WILL BE FROM THE LOWER TO MIDDLE 70S AND IN LINE WITH MAV MOS./40/ LONG TERM... MUCH QUIETER CONDITIONS ADVERTISED IN THE LONGER TERM. LAST TRACES OF DEEPER MOISTURE NOTED OVER EXTREME SERN MS CORNER SATURDAY...LEAVING FORECAST AREA GENERALLY DRY. LOW LEVEL NLY FLOW DEVELOPS AS SURFACE/850 MB RIDGING TAKES SHAPE UPSTREAM. WEAK LOW LEVEL RIDGING MOVES OVER THE FORECAST AREA SATURDAY EVENING AND REMAINS OVER THE REGION THROUGH THE EXTENDED. LOW LEVEL SLY FLOW RETURNS BY MONDAY AS SURFACE RIDGING EDGES SLIGHTLY EWD BUT MAINTAINS ITS HOLD ON REGIONAL WEATHER. A WEAK COLD FRONT DROPS INTO THE LOWER MS VALLEY AND DISSIPATES AS IT STALLS OVER CENTRAL/SRN ZONES TUESDAY AND WEDNESDAY. WILL KEEP SLIGHT CHANCE POPS OVER SRN ZONES FOR NOW BUT THE LIMITED MOISTURE AVAILABLE LOOKS UNORGANIZED. WE WILL SEE COOLER LOW TEMPS LATE IN THE WEEK...ESPECIALLY OVER NRN ZONES...AND WARMER AFTERNOON HIGHS ACROSS THE ARKLAMISS WHEN THE AIRMASS BEGINS TO DRY AND CLOUDS BEGINS TO CLEAR. /03/ && .AVIATION...UPDATED...THUNDERSTORM COVERAGE SHOULD BE LIMITED TO THE EAST THIS AFTERNOON. VFR CONDITIONS WILL PREVAIL OVER THE WESTERN HALF BUT OCCASIONAL CEILINGS BELOW 3KFT IN THE NORTHWEST COULD BE OBSERVED AS THE CLOUD DECK ASSOCIATED WITH THE REMNANTS OF GUSTAV DROPS SOUTHEAST. && .JAN WATCHES/WARNINGS/ADVISORIES... MS...FLASH FLOOD WATCH UNTIL 4 PM CDT THIS AFTERNOON FOR MSZ056-057- 064>066-072>074. FLASH FLOOD WATCH UNTIL 7 AM CDT THIS MORNING FOR MSZ018-019- 025>028-034>037-040>044-047>050-053>055-059>063. LA...FLASH FLOOD WATCH UNTIL 7 AM CDT THIS MORNING FOR LAZ007>009-015- 016-023>026. AR...FLASH FLOOD WATCH UNTIL 7 AM CDT THIS MORNING FOR ARZ074-075. && $$ 40/03 ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 424 AM CDT THU SEP 4 2008 .SHORT TERM...SHORT TERM(TODAY THROUGH FRIDAY)...THERE FINALLY APPEARS TO BE LIGHT AT THE END OF THE GUSTAV TUNNEL THIS MORNING. SOME INCREDIBLE RAINFALL TOTALS ABOVE 20 INCHES WILL BE PUBLISHED LATER THIS MORNING AS THEY BECOME AVAILABLE. LATEST SATELLITE IMAGERY/SURFACE ANALYSIS SHOWS REMNANTS OF GUSTAV ACROSS CENTRAL ARKANSAS MOVING NNE. LAST CONVECTIVE BAND ROUGHLY ALONG INTERSTATE 55 CREEPING STEADILY EWD THIS MORNING WITH DECREASING RAINFALL RATES OF GENERALLY ABOUT 1 INCH/HOUR OR LESS. RISING SURFACE PRESSURES AND WEAKENING LOW LEVEL WINDS APPEAR TO BE LIMITING THE INTENSITY OF THE BAND. AS FAR AS FLASH FLOOD POTENTIAL...ONGOING FLOODING DICTATES THAT WE NOT CANCEL THE FFA UNTIL RAIN COMPLETELY GONE. WE WILL LET THE FLASH FLOOD WATCH EXPIRE FOR MOST AREAS THIS MORNING BUT EXTEND IT FOR SERN/SCNTRL AREAS THROUGH THE AFTERNOON. THE REMNANTS OF THE RAIN BAND WILL MOVE THROUGH ERN ZONES TODAY. RAIN PROCESSES WILL BECOME MORE OF A HYBRID BETWEEN TROPICAL AND CONVECTIVE AND MID 70S DEWPOINTS MAY HELP ENHANCE THUNDERSTORM DEVELOPMENT ALONG AND AHEAD OF THE RAIN BAND TODAY. SHORT RANGE NAM12/RUC SHOW THAT THE REMNANTS OF GUSTAV PUSH AWAY ACROSS SOUTHERN MISSOURI THIS MORNING AND INTO SRN ILLINOIS TONIGHT. THIS SHOULD DIMINISH THE HEAVY RAIN POTENTIAL BY TONIGHT ALTHOUGH A WEAK SURFACE TROUGH/BOUNDARY WILL BE TRAILING INTO ERN MS. AFTERNOON MLCAPES PROGGED TO REACH 1200-1600J/KG OVER AT LEAST SERN HALF OF CWFA WITH K INDEXES HOLDING IN THE M30S. DECENT FORWARD CELL MOTIONS SHOULD LIMIT RAIN VOLUMES HOPEFULLY. LOOK FOR THE WEAK CONVERGENT AXIS TO EXIT TO THE E LATER THIS EVENING. THE ARKLAMISS SHOULD DRY OUT FROM THE WEST LATER FRIDAY WITH MORE ABUNDANT SUNSHINE TO HELP IN EVAPORATION. AS FAR AS TEMPS ARE CONCERNED BELIEVE THAT SOGGY GROUND WILL LIMIT WARMING FOR TODAY WHILE EXPECT NEAR CLIMATOLOGY HIGHS MORE PROBABLE ON FRIDAY SO MADE SOME SLIGHT UPWARD ADJUSTMENTS TO GUIDANCE. OVERNIGHT LOWS WILL BE FROM THE LOWER TO MIDDLE 70S AND IN LINE WITH MAV MOS./40/ .LONG TERM... MUCH QUIETER CONDITIONS ADVERTISED IN THE LONGER TERM. LAST TRACES OF DEEPER MOISTURE NOTED OVER EXTREME SERN MS CORNER SATURDAY...LEAVING FORECAST AREA GENERALLY DRY. LOW LEVEL NLY FLOW DEVELOPS AS SURFACE/850 MB RIDGING TAKES SHAPE UPSTREAM. WEAK LOW LEVEL RIDGING MOVES OVER THE FORECAST AREA SATURDAY EVENING AND REMAINS OVER THE REGION THROUGH THE EXTENDED. LOW LEVEL SLY FLOW RETURNS BY MONDAY AS SURFACE RIDGING EDGES SLIGHTLY EWD BUT MAINTAINS ITS HOLD ON REGIONAL WEATHER. A WEAK COLD FRONT DROPS INTO THE LOWER MS VALLEY AND DISSIPATES AS IT STALLS OVER CENTRAL/SRN ZONES TUESDAY AND WEDNESDAY. WILL KEEP SLIGHT CHANCE POPS OVER SRN ZONES FOR NOW BUT THE LIMITED MOISTURE AVAILABLE LOOKS UNORGANIZED. WE WILL SEE COOLER LOW TEMPS LATE IN THE WEEK...ESPECIALLY OVER NRN ZONES...AND WARMER AFTERNOON HIGHS ACROSS THE ARKLAMISS WHEN THE AIRMASS BEGINS TO DRY AND CLOUDS BEGINS TO CLEAR. && .AVIATION...MOSTLY MVFR CEILINGS THIS MORNING WITH NARROW BAND OF HEAVY RAINS PRODUCING SOME IFR CONDITIONS FOR UP TO 2 HOUR INTERVALS. ALSO EXPECTING AREAS OF IFR FOG/STRATUS TO DEVELOP TO THE WEST OF THE RAINS PER LOW CLOUD IMAGERY TRENDS. MORE WIDESPREAD VFR PERIODS SHOULD BE SEEN AT TIMES AFTER ABOUT 16Z THIS MORNING WITH BROKEN CLOUDS 3-4K FEET AS RAIN BAND BECOMES LESS ORGANIZED OVER TIME. SCATTERED CONVECTION SHOULD ALSO DEVELOP DURING THE AFTERNOON AND EVENING FOR AT LEAST SE HALF OF CWFA./40/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 85 69 86 68 / 49 44 30 21 MERIDIAN 87 70 86 69 / 61 53 51 26 VICKSBURG 84 68 87 66 / 36 31 15 16 HATTIESBURG 88 71 86 70 / 72 43 52 23 NATCHEZ 84 69 86 68 / 41 22 17 13 GREENVILLE 83 67 87 64 / 39 23 10 12 GREENWOOD 83 69 86 65 / 50 36 22 16 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...FLASH FLOOD WATCH UNTIL 4 PM CDT THIS AFTERNOON FOR MSZ056-057- 064>066-072>074. FLASH FLOOD WATCH UNTIL 7 AM CDT THIS MORNING FOR MSZ018-019- 025>028-034>037-040>044-047>050-053>055-059>063. LA...FLASH FLOOD WATCH UNTIL 7 AM CDT THIS MORNING FOR LAZ007>009-015- 016-023>026. AR...FLASH FLOOD WATCH UNTIL 7 AM CDT THIS MORNING FOR ARZ074-075. && $$ 40/03 ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 837 PM CDT THU SEP 4 2008 .DISCUSSION... ONGOING FIRST PERIOD FORECAST LOOKS RIGHT ON TRACK. THE ONLY CHANGE THAT MAY BE NEEDED WITHIN THE GRIDS REGARDS SKY COVER. ISENTROPIC DOWNGLIDE WITHIN THE LOWEST FEW KILOMETERS CONTINUE TO ERODE CLOUD COVER FROM THE WEST. EVENTUALLY THIS DOWNGLIDE OCCURS ACROSS MOST OF THE CWA AFTER MIDNIGHT...ACCORDING TO THE RUC. THEREFORE FULL SKY COVERAGE THROUGH THE ENTIRE NIGHT MAY BE A LITTLE AGGRESSIVE. WILL CONTINUE TO MONITOR FOR CHANGES WITHIN THE GRIDS. WE WILL ALSO MONITOR FOG POTENTIAL. CAN NOT RULE OUT DENSE FOG DEVELOPING AS SKIES CLEAR. VERY MOIST SOIL CONDITIONS ALONG WITH A DECREASE IN BOUNDARY LAYER MIXING WOULD ENHANCE FOG DEVELOPMENT. THE GREATEST RISK AREA FOR DENSE FOG INITIALLY...WILL OCCUR OVER EXTREME SOUTHEAST KANSAS AND WESTERN MISSOURI. CRAMER && .AVIATION... THE PRIMARY FORECAST CHALLENGE WITHIN THE AVIATION FORECASTS REGARDED CEILING HEIGHTS AND POTENTIAL FOG OVERNIGHT. CEILINGS OVER THE SPRINGFIELD AIRPORT SHOULD CONTINUE WITHIN THE IFR CATEGORY THROUGH THIS EVENING...AND POSSIBLY CLEAR OUT SOMETIME AFTER MIDNIGHT. DRIER AIR ALOFT IS ADVECTING IN FROM EASTERN KANSAS...WHICH SHOULD ELIMINATE CLOUD COVER AT BOTH JOPLIN AND SPRINGFIELD. HOWEVER...ONCE THE SKIES CLEAR...FOG WILL DEVELOP AS WIND SPEEDS BECOME LIGHT...ELIMINATING ANY BOUNDARY LAYER MIXING THAT MIGHT EXIST. MOIST SOIL CONDITIONS WILL ALSO ENHANCE FOG DEVELOPMENT WHILE OVERNIGHT LOWS ARE EXPECTED TO COOL WELL BELOW THE CROSS-OVER TEMPERATURE. WITHIN BOTH TERMINAL AERODROME FORECASTS (TAFS)...I HAVE IFR FOG DEVELOPING AT AROUND 10Z...WITH MVFR FOG SOMETIME AROUND MIDNIGHT. WILL MONITOR CEILINGS AND VISIBILITIES CLOSELY THROUGH THE NIGHT AND ISSUE UPDATED TAFS WHEN NEEDED. CRAMER && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 1239 AM CDT THU SEP 4 2008 ...UPDATE TO AVIATION... .UPDATE... WIDESPREAD RAINFALL CONTINUES TO MAINTAIN ITS GRASP ON THE REGION. HEAVY RAINFALL AND FLOODING IS EXPECTED OVERNIGHT. THE REMNANT LOW FROM GUSTAV IS BEGINNING TO MOVE TO THE NORTHEAST. OVER THE PAST FEW HOURS...SURFACE PRESSURE FALLS HAVE BEGUN TO FOCUS ON SOUTHWEST MISSOURI AND THIS TREND IS EXPECTED TO CONTINUE. SHORT TERM MODELS HAVE THIS LOW MOVEMENT PEGGED AND THE LOW ITSELF SHOULD ENTER THE SOUTHERN CWA BY DAYBREAK THURSDAY. DECENT PRESSURE GRADIENT ASSOCIATED WITH THIS LOW WILL KEEP WINDS ON THE GUSTY SIDE...OCCASIONALLY TO 30 MPH. RECENT WAT VAP IMAGERY AND RUC INITIALIZATION OF UPPER LEVEL VORTICITY INDICATE THAT THE UPPER LEVEL FORCING IS ALSO ON THE MOVE. DEEP LARGE SCALE LIFT WILL PERSIST ACROSS THE AREA FOR THE NEXT SEVERAL HOURS. AS A RESULT MODERATE TO HEAVY RAINFALL IS EXPECTED AREA WIDE FOR THE REMAINDER OF TONIGHT. TO THIS POINT...THIS WIDESPREAD RAINFALL HAS ONLY RESULTED IN ISOLATED FLOODING. HOWEVER...A RECENT PEER AT AREA RIVER GAGES INDICATES THAT AREA CREEKS AND RIVERS ARE STARTING TO RESPOND. CONTINUED HOURLY RAINFALL RATES OF ONE QUARTER TO ONE HALF INCH WILL RESULT IN INCREASED RESPONSES OVERNIGHT. SMALL...NARROW EMBEDDED CONVECTIVE ELEMENTS WILL RESULT IN HOURLY RAINFALL RATES IN THE ONE INCH TO ONE AND ONE HALF INCH RANGE. ADDITIONAL AREAL FLOOD WARNINGS AND RIVER FLOOD WARNINGS SHOULD BE EXPECTED TONIGHT. REGARDING RADAR RAINFALL ESTIMATION...AFTER COMPARING RECENT RAINFALL TOTALS FROM ACROSS THE AREA THE RADAR HAS BEEN UNDERESTIMATING IN SPOTS. AFTER COLLABORATION WITH THE MBRFC... THE KSGF RADAR Z/R RELATIONSHIP HAS BEEN CHANGED TO STRATIFORM MODE. RAINFALL HAS BEEN MORE STRATIFORM THAN CONVECTIVE THE PAST SEVERAL HOURS AND THIS Z/R RELATIONSHIP SHOULD ESTIMATE TONIGHTS RAINFALL THE BEST. ANY CONVECTIVE ELEMENTS WITHIN THIS STRATIFORM RAIN MAY BE UNDERESTIMATED AT TIMES. RAIN IS EXPECTED ALL NIGHT TONIGHT WITH TWO TO SIX INCHES OF STORM TOTAL RAINFALL COMMON BY DAYBREAK THURSDAY. LOCALLY HIGHER AMOUNTS ARE EXPECTED. RAINFALL WILL TAPER OFF FROM SW TO NE LATE TONIGHT THROUGH THE DAYLIGHT HOURS OF THURSDAY MORNING. NO CHANGES TO THE FLOOD WATCH ARE PLANNED AT THIS TIME. GAGAN && .DISCUSSION... ...EXCESSIVE RAINFALL AND FLOODING... THE FOCUS OF THE FORECAST REMAINS ON THE POTENTIAL OF WIDESPREAD RAIN PRODUCING EXCESSIVE RAINFALL AND FLOODING. RAINFALL ASSOCIATED WITH TROPICAL MOISTURE FROM GUSTAV CONTINUES ACROSS SOUTHEAST KANSAS AND SOUTHWEST MISSOURI. SO FAR...RAINFALL AMOUNTS GENERALLY HAVE RANGED FROM ONE HALF TO AN INCH NORTH OF THE INTERSTATE 44 CORRIDOR WITH AMOUNTS RANGING FROM 1 INCH TO 3 INCHES SOUTH OF THE INTERSTATE 44 CORRIDOR. THE HEAVIEST RAINFALL HAS OCCURRED ALONG THE ARKANSAS BORDER WHERE RAINFALL AMOUNTS OF 2 TO 3 INCHES HAVE BEEN REALIZED. SHORT TERM (TODAY THROUGH THURSDAY)... TROPICAL DEPRESSION GUSTAV CENTERED OVER SOUTHERN ARKANSAS CONTINUES TO GRADUALLY MOVE NORTH. DEEP TROPICAL MOISTURE...WITH PRECIPITABLE WATER VALUES NEAR 2 INCHES...CONTINUES TO OVERRUN A SURFACE FRONT EXTENDING FROM NEAR SALEM TO CASSVILLE. ACROSS THE CENTRAL OZARKS...HOURLY RAINFALL RATES HAVE RANGED UP TO A QUARTER OF AN INCH PER HOUR WHILE RATES OVER AN INCH AND A HALF PER HOUR HAVE OCCURRED AT TIMES ACROSS SOUTHERN MISSOURI. THE THREAT FOR HEAVY RAIN AND FLOODING WILL BE INCREASING GREATLY TONIGHT INTO THURSDAY MORNING. THE GFS/NAM/ECMWF REMAIN CONSISTENT WITH TRACKING THE VERTICALLY STACKED LOW ALONG WITH THE REMNANTS OF GUSTAV NORTH INTO THE OZARKS TONIGHT AND MOVING THE LOW NORTHEAST OF THE FORECAST AREA BY LATE THURSDAY. NO CHANGES WILL BE MADE TO THE FLASH FLOOD WATCH. HEAVY RAIN WILL INCREASE IN COVERAGE AS STRONGER LIFT ASSOCIATED WITH THE 850MB LOW TRACKS THROUGH THE OZARKS. DURING THE OVERNIGHT HOURS...THERE IS OFTEN AN INCREASE IN RAIN INTENSITY WITH TROPICAL AIRMASSES DUE TO NOCTURNAL PROCESSES AND TONIGHT SHOULD BE NO DIFFERENT. RAINFALL AMOUNTS OF 2 TO 6 INCHES WITH LOCALLY HIGHER AMOUNTS REMAINS LIKELY. FLOODING WILL REMAIN POSSIBLE IN LOW LYING AND POOR DRAINAGE AREAS...LOW WATER CROSSINGS...SOME URBAN AREAS AND ACROSS THE WHITE...GASCONADE...BIG PINEY...NIANGUA...OSAGE AND SAC RIVER BASINS. THE RAIN WILL GRADUALLY DECREASE IN COVERAGE AND INTENSITY FROM WEST TO EAST ACROSS THE FORECAST AREA THURSDAY AS AN UPPER LEVEL TROUGH IN THE NORTHERN PLAINS KICKS THE REMNANTS OF GUSTAV NORTHEAST. THE GFS AND NAM DEPICT STRONG ISENTROPIC DOWNGLIDE ALONG THE 320K SURFACE WHICH WOULD END THE RAIN CHANCES SOONER THAN THE GOING FORECAST. WITH A TROPICAL AIRMASS IN PLACE...JUST THINK THAT THE MODELS ARE BEING OVERLY AGGRESSIVE IN DRYING OUT THE COLUMN. ISOLATED BRIEF AND WEAK TORNADOES WILL REMAIN POSSIBLE TONIGHT THROUGH THURSDAY AFTERNOON ACROSS SOUTHWEST AND SOUTH CENTRAL MISSOURI...PRIMARILY ON THE EAST AND NORTHEAST SIDES OF THE LOW TRACKING THROUGH THE OZARKS. THE GFS CONTINUES TO PROG 0 TO 1KM HELICITY VALUES NEAR 500 M2/S2 WHILE LCL HEIGHTS WILL REMAIN LOW WITH A SATURATED AIRMASS. WHERE STRONGER UPDRAFTS DEVELOP THERE WILL BE AN INCREASED TORNADO POTENTIAL WITH INSTABILITY REMAINING A LIMITING FACTOR. ANGLE LONG TERM (FRIDAY THROUGH TUESDAY)... DRY WEATHER RETURNS FRIDAY AS SURFACE HIGH PRESSURE BUILDS INTO THE REGION. THE FOG POTENTIAL WILL NEED TO BE MONITORED FRIDAY NIGHT AND SATURDAY NIGHT WITH LIGHTER WINDS AND A WET GROUND. A BROAD AND DEEPENING UPPER LEVEL TROUGH WILL BE IN PLACE OVER THE CENTRAL UNITED STATES THROUGH THE WEEKEND INTO EARLY NEXT WEEK. A STRONG COLD FRONT IS EXPECTED TO MOVE THROUGH THE PLAINS AND THE OZARKS LATE SUNDAY INTO MONDAY BRINGING CHANCES FOR SCATTERED RAIN SHOWERS. ANGLE && .CLIMATE... HEAVY RAINFALL ASSOCIATED WITH TROPICAL DEPRESSION GUSTAV HAS PRODUCED SOME SIGNIFICANT RAINFALL ACROSS THE REGION OVER THE LAST 24 HOURS. REPORTS HAVE RANGED FROM 1 TO 3 INCHES WITH SOME ISOLATED REPORTS OF HIGHER AMOUNTS. SEVERAL HEAVY BANDS OF PRECIPITATION ARE EXPECTED TO MOVE ACROSS THE OZARKS OVERNIGHT WHICH WILL ADD TO THE RAINFALL TOTALS. A RECORD RAINFALL FOR SPRINGFIELD OF 1.62 INCHES OF RAIN EXCEEDED THE OLD RECORD OF 1.38 INCHES SET IN 1970. THIS OCCURRED AT 9 PM AND ADDITIONAL RAINFALL WILL LIKELY BREAK OTHER RECORDS ACROSS THE AREA. THE FOLLOWING ARE THE RECORDS FOR THE FOUR ASOS SITES IN THE OZARKS FOR SEPTEMBER 3RD AND 4TH. AMOUNTS ARE IN INCHES WITH THE YEAR OF THE PREVIOUS RECORD. ASOS WED THURS AS OF 9 PM WED SPRINGFIELD 1.38 1970 1.54 1937 1.62 NEW RECORD JOPLIN 2.24 1970 0.76 1961 1.52 VICHY/ROLLA 1.87 1993 2.65 1965 0.56 WEST PLAINS 3.02 1988 1.70 1970 2.42 HATCH .AVIATION... FOR THE 06Z TAF PACKAGE...PRIMARY CONCERN ONCE AGAIN REVOLVES AROUND THE PROLONGED IFR EVENT. WIDESPREAD RAINFALL WILL CONTINUE ALL NIGHT. VISIBILITY WILL BE CONSISTENTLY REDUCED TO BETWEEN 2 AND 4 MILES WITHIN THIS RAIN. IFR CIGS WILL PERSIST WITH LIFR POSSIBLE TOWARD SUNRISE. LOW PRESSURE APPROACHING FROM THE SOUTHWEST OVER THE NEXT FEW HOURS WILL MAINTAIN GUSTY NNE WINDS. GRADUAL IMPROVEMENT IS EXPECTED DURING THE DAYLIGHT HOURS OF THURSDAY...BUT IT WILL BE SLOW TO COME. RAIN WILL END IN THE MORNING AND A DELIBERATE SLOW LIFTING OF CIGS HAS BEEN PROGGED. SHOULD REMAIN IFR ALL MORNING INTO THE EARLY AFTERNOON AND RISE INTO MVFR DURING THE AFTERNOON. CLEARING IS CONTINGENT ON THE EXIT SPEED OF THIS SYSTEM AND HAVE REMAINED PESSIMISTIC BASED ON PAST MODEL/MOS PERFORMANCE. IF/WHEN CLEARING OCCURS TOMORROW NIGHT. FOG WILL BECOME A MAJOR CONCERN. GAGAN && .SGF WATCHES/WARNINGS/ADVISORIES... MO...FLASH FLOOD WATCH THROUGH FRIDAY MORNING FOR MOZ055>058-066>071- 077>083-088>098-101>106. KS...FLASH FLOOD WATCH THROUGH FRIDAY MORNING FOR KSZ073-097-101. && $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 900 PM CDT WED SEP 3 2008 ...MESOSCALE CONVECTIVE DISCUSSION... .UPDATE... WIDESPREAD RAINFALL CONTINUES TO MAINTAIN ITS GRASP ON THE REGION. HEAVY RAINFALL AND FLOODING IS EXPECTED OVERNIGHT. THE REMNANT LOW FROM GUSTAV IS BEGINNING TO MOVE TO THE NORTHEAST. OVER THE PAST FEW HOURS...SURFACE PRESSURE FALLS HAVE BEGUN TO FOCUS ON SOUTHWEST MISSOURI AND THIS TREND IS EXPECTED TO CONTINUE. SHORT TERM MODELS HAVE THIS LOW MOVEMENT PEGGED AND THE LOW ITSELF SHOULD ENTER THE SOUTHERN CWA BY DAYBREAK THURSDAY. DECENT PRESSURE GRADIENT ASSOCIATED WITH THIS LOW WILL KEEP WINDS ON THE GUSTY SIDE...OCCASIONALLY TO 30 MPH. RECENT WAT VAP IMAGERY AND RUC INITIALIZATION OF UPPER LEVEL VORTICITY INDICATE THAT THE UPPER LEVEL FORCING IS ALSO ON THE MOVE. DEEP LARGE SCALE LIFT WILL PERSIST ACROSS THE AREA FOR THE NEXT SEVERAL HOURS. AS A RESULT MODERATE TO HEAVY RAINFALL IS EXPECTED AREA WIDE FOR THE REMAINDER OF TONIGHT. TO THIS POINT...THIS WIDESPREAD RAINFALL HAS ONLY RESULTED IN ISOLATED FLOODING. HOWEVER...A RECENT PEER AT AREA RIVER GAGES INDICATES THAT AREA CREEKS AND RIVERS ARE STARTING TO RESPOND. CONTINUED HOURLY RAINFALL RATES OF ONE QUARTER TO ONE HALF INCH WILL RESULT IN INCREASED RESPONSES OVERNIGHT. SMALL...NARROW EMBEDDED CONVECTIVE ELEMENTS WILL RESULT IN HOURLY RAINFALL RATES IN THE ONE INCH TO ONE AND ONE HALF INCH RANGE. ADDITIONAL AREAL FLOOD WARNINGS AND RIVER FLOOD WARNINGS SHOULD BE EXPECTED TONIGHT. REGARDING RADAR RAINFALL ESTIMATION...AFTER COMPARING RECENT RAINFALL TOTALS FROM ACROSS THE AREA THE RADAR HAS BEEN UNDERESTIMATING IN SPOTS. AFTER COLLABORATION WITH THE MBRFC... THE KSGF RADAR Z/R RELATIONSHIP HAS BEEN CHANGED TO STRATIFORM MODE. RAINFALL HAS BEEN MORE STRATIFORM THAN CONVECTIVE THE PAST SEVERAL HOURS AND THIS Z/R RELATIONSHIP SHOULD ESTIMATE TONIGHTS RAINFALL THE BEST. ANY CONVECTIVE ELEMENTS WITHIN THIS STRATIFORM RAIN MAY BE UNDERESTIMATED AT TIMES. RAIN IS EXPECTED ALL NIGHT TONIGHT WITH TWO TO SIX INCHES OF STORM TOTAL RAINFALL COMMON BY DAYBREAK THURSDAY. LOCALLY HIGHER AMOUNTS ARE EXPECTED. RAINFALL WILL TAPER OFF FROM SW TO NE LATE TONIGHT THROUGH THE DAYLIGHT HOURS OF THURSDAY MORNING. NO CHANGES TO THE FLOOD WATCH ARE PLANNED AT THIS TIME. GAGAN && .DISCUSSION... ...EXCESSIVE RAINFALL AND FLOODING... THE FOCUS OF THE FORECAST REMAINS ON THE POTENTIAL OF WIDESPREAD RAIN PRODUCING EXCESSIVE RAINFALL AND FLOODING. RAINFALL ASSOCIATED WITH TROPICAL MOISTURE FROM GUSTAV CONTINUES ACROSS SOUTHEAST KANSAS AND SOUTHWEST MISSOURI. SO FAR...RAINFALL AMOUNTS GENERALLY HAVE RANGED FROM ONE HALF TO AN INCH NORTH OF THE INTERSTATE 44 CORRIDOR WITH AMOUNTS RANGING FROM 1 INCH TO 3 INCHES SOUTH OF THE INTERSTATE 44 CORRIDOR. THE HEAVIEST RAINFALL HAS OCCURRED ALONG THE ARKANSAS BORDER WHERE RAINFALL AMOUNTS OF 2 TO 3 INCHES HAVE BEEN REALIZED. SHORT TERM (TODAY THROUGH THURSDAY)... TROPICAL DEPRESSION GUSTAV CENTERED OVER SOUTHERN ARKANSAS CONTINUES TO GRADUALLY MOVE NORTH. DEEP TROPICAL MOISTURE...WITH PRECIPITABLE WATER VALUES NEAR 2 INCHES...CONTINUES TO OVERRUN A SURFACE FRONT EXTENDING FROM NEAR SALEM TO CASSVILLE. ACROSS THE CENTRAL OZARKS...HOURLY RAINFALL RATES HAVE RANGED UP TO A QUARTER OF AN INCH PER HOUR WHILE RATES OVER AN INCH AND A HALF PER HOUR HAVE OCCURRED AT TIMES ACROSS SOUTHERN MISSOURI. THE THREAT FOR HEAVY RAIN AND FLOODING WILL BE INCREASING GREATLY TONIGHT INTO THURSDAY MORNING. THE GFS/NAM/ECMWF REMAIN CONSISTENT WITH TRACKING THE VERTICALLY STACKED LOW ALONG WITH THE REMNANTS OF GUSTAV NORTH INTO THE OZARKS TONIGHT AND MOVING THE LOW NORTHEAST OF THE FORECAST AREA BY LATE THURSDAY. NO CHANGES WILL BE MADE TO THE FLASH FLOOD WATCH. HEAVY RAIN WILL INCREASE IN COVERAGE AS STRONGER LIFT ASSOCIATED WITH THE 850MB LOW TRACKS THROUGH THE OZARKS. DURING THE OVERNIGHT HOURS...THERE IS OFTEN AN INCREASE IN RAIN INTENSITY WITH TROPICAL AIRMASSES DUE TO NOCTURNAL PROCESSES AND TONIGHT SHOULD BE NO DIFFERENT. RAINFALL AMOUNTS OF 2 TO 6 INCHES WITH LOCALLY HIGHER AMOUNTS REMAINS LIKELY. FLOODING WILL REMAIN POSSIBLE IN LOW LYING AND POOR DRAINAGE AREAS...LOW WATER CROSSINGS...SOME URBAN AREAS AND ACROSS THE WHITE...GASCONADE...BIG PINEY...NIANGUA...OSAGE AND SAC RIVER BASINS. THE RAIN WILL GRADUALLY DECREASE IN COVERAGE AND INTENSITY FROM WEST TO EAST ACROSS THE FORECAST AREA THURSDAY AS AN UPPER LEVEL TROUGH IN THE NORTHERN PLAINS KICKS THE REMNANTS OF GUSTAV NORTHEAST. THE GFS AND NAM DEPICT STRONG ISENTROPIC DOWNGLIDE ALONG THE 320K SURFACE WHICH WOULD END THE RAIN CHANCES SOONER THAN THE GOING FORECAST. WITH A TROPICAL AIRMASS IN PLACE...JUST THINK THAT THE MODELS ARE BEING OVERLY AGGRESSIVE IN DRYING OUT THE COLUMN. ISOLATED BRIEF AND WEAK TORNADOES WILL REMAIN POSSIBLE TONIGHT THROUGH THURSDAY AFTERNOON ACROSS SOUTHWEST AND SOUTH CENTRAL MISSOURI...PRIMARILY ON THE EAST AND NORTHEAST SIDES OF THE LOW TRACKING THROUGH THE OZARKS. THE GFS CONTINUES TO PROG 0 TO 1KM HELICITY VALUES NEAR 500 M2/S2 WHILE LCL HEIGHTS WILL REMAIN LOW WITH A SATURATED AIRMASS. WHERE STRONGER UPDRAFTS DEVELOP THERE WILL BE AN INCREASED TORNADO POTENTIAL WITH INSTABILITY REMAINING A LIMITING FACTOR. ANGLE LONG TERM (FRIDAY THROUGH TUESDAY)... DRY WEATHER RETURNS FRIDAY AS SURFACE HIGH PRESSURE BUILDS INTO THE REGION. THE FOG POTENTIAL WILL NEED TO BE MONITORED FRIDAY NIGHT AND SATURDAY NIGHT WITH LIGHTER WINDS AND A WET GROUND. A BROAD AND DEEPENING UPPER LEVEL TROUGH WILL BE IN PLACE OVER THE CENTRAL UNITED STATES THROUGH THE WEEKEND INTO EARLY NEXT WEEK. A STRONG COLD FRONT IS EXPECTED TO MOVE THROUGH THE PLAINS AND THE OZARKS LATE SUNDAY INTO MONDAY BRINGING CHANCES FOR SCATTERED RAIN SHOWERS. ANGLE && .AVIATION... FOR THE 00Z TAF PACKAGE...PRIMARY CONCERNS FOR THIS FORECAST DEAL WITH RAINFALL AND PROLONGED IFR...LIKELY LIFR CONDITIONS. WIDESPREAD RAINFALL WILL CONTINUE ACROSS THE REGION TONIGHT...WITH ONLY A FEW TEMPORARY BREAKS IN THE ACTION. CIGS HAVE BEEN IFR AT JLN MOST OF TODAY AND THIS WILL NOT CHANGE. A SLOW DESCENT INTO LIFR IS EXPECTED. AT SGF...CIGS HAVE BEEN A BIT MORE VARIABLE DURING THE PAST HOUR OR SO. THIS IS DUE...IN PART...TO SOME BREAKS IN THE RAINFALL. WITH CONTINUED NORTHEAST FLOW EXPECTED...IFR WILL BE THE RULE THROUGH AT LEAST TOMORROW MORNING. VISIBILITY REDUCTIONS WILL BE INTIMATELY TIED TO RAINFALL THIS EVENING...BUT AS WINDS SLACKEN A BIT TOWARDS SUNRISE THURSDAY...LIFR VIS IS POSSIBLE. SPEAKING OF WINDS...THEY WILL BE GUSTY OUT OF THE NORTHEAST AS THE REMNANT LOW FROM GUSTAV MOVES TO THE NORTHEAST... SWITCHING TO THE NORTHWEST DURING THE DAYLIGHT HOURS OF THURSDAY MORNING. GAGAN && .SGF WATCHES/WARNINGS/ADVISORIES... MO...FLASH FLOOD WATCH THROUGH FRIDAY MORNING FOR MOZ055>058-066>071- 077>083-088>098-101>106. KS...FLASH FLOOD WATCH THROUGH FRIDAY MORNING FOR KSZ073-097-101. && $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GLASGOW MT 930 AM MDT THU SEP 4 2008 .SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH SATURDAY... MORNING UPDATE...MINOR UPDATE THIS MORNING TO INCREASE POPS THIS AFTERNOON ALONG THE EASTERN BORDER OF THE CWA. A FEW SHOWERS ROTATING SOUTH OUT OF CANADA THIS MORNING WITH THE SURFACE LOW OVER NORTHCENTRAL SD STRETCHING NORTHWESTWARD INTO THE LAKE SAKAKAWEA REGION. 500 MB TROF IS JUST EAST OF THE ND/MT LINE THIS MORNING. FOG HAS BASICALLY DISSIPATED EVERYWHERE...JUST A FEW ISOLATED PATCHES REMAINING SO HAVE REMOVED THE FOG WORDING FROM THE FORECAST AS WELL. FRANSEN PREVIOUS SHORT TERM DISCUSSION...THE LARGE SCALE PATTERN HAS THE JETSTREAM CONTINUING TO BE STRONGER AND FARTHER S THAN NORMAL FOR THIS TIME OF YEAR. THERE IS UPPER RIDGING OFF THE W COAST...WITH NE MT IN UPPER TROUGHING. MODELS HAVE THICKNESSES AND UPPER HEIGHTS BELOW NORMAL FOR THIS TIME OF YEAR TOO. THESE DON`T CHANGE MUCH...SO TEMPS TO STAY BELOW NORMAL IN THE SHORT TERM. THE UPPER TROUGH MOVING ENE ACROSS OUR AREA YESTERDAY AND LAST NIGHT DEVELOPED A CLOSED CIRCULATION OVER NE MT. THIS ENHANCED PRECIP IN OUR NE...BUT HAS NOW MOVED OUT OF OUR AREA. RUC HAD A GOOD HANDLE ON THE SYSTEM...BUT NOW ITS TOO SLOW COMPARED TO OTHER MODELS AND EXPECT ANY LINGERING SHOWER ACTIVITY IN OUR EXTREME NE TO BE DONE BY EARLY THIS MORN. QUITE A BIT OF PARTIAL CLEARING ELSEWHERE...MORE THAN EARLIER EXPECTED. SURFACE PRESSURE GRADIENTS BECOMING VERY WEAK AS WELL. THIS IS COMBINING WITH THE MOIST AIRMASS AT LOWER LEVELS TO CAUSE MOST OF THE CWA TO BE NEARLY SATURATED...TEMP/DWPOINT SPREADS GENERALLY LESS THAN 3F. THIS WILL MEAN PATCHES OF FOG ARE POSSIBLE AT MOST ANY LOCATION IN OUR CWA. THIS ESPECIALLY TRUE IN OUR NE WHERE LOW LEVELS MOST SATURATED FROM MOST SIGNIFICANT RAINFALL THAT JUST ENDED. ANOTHER AREA ALREADY WITH FOG IS NOW SEEN ON SATELLITE FOG LOOP ACROSS PARTS OF OUR SE...WIBAUX....DAWSON...AND RICHLAND COUNTIES. ALTHOUGH UPPER TROUGH LINGERS OVER THE AREA TODAY...THE MAIN DYNAMICS HAVE EXITED INTO ND AND MODELS INDICATE LITTLE SHORTWAVE ACTIVITY. ENOUGH MOISTURE AND INSTABILITY TO KEEP ISOLATED SHOWERS IN THE FORECAST FOR AFTERNOON AND EVE. WILL GO WITH NAM FORECAST SOUNDINGS...THAT ARE QUITE BORDERLINE FOR ANY TSTORM ACTIVITY...SO WILL LEAVE OUT MENTION. ONLY SLIGHT CHANGES IN UPPER PATTERN FOR FRI...BUT SOME DRYING OF THE AIRMASS WITH PRECIP WATER DOWN TO 0.50 OR LESS AND FORECAST SOUNDINGS ALL ABOVE ZERO. NO SIGNIFICANT SHORTWAVES IN SIGHT. THEREFORE EXPECT A LITTLE MORE SUNSHINE AND A LITTLE WARMER TEMPS FRI WITH LITTLE OR NO SHOWERS. THE NEXT MORE SIGNIFICANT SHORTWAVE ARRIVES IN NW FLOW SAT. MODELS SHOW BEST DYNAMICS AND MOISTURE IN OUR NE. AIRMASS AGAIN MOISTENS A BIT MORE AND BECOMES SLIGHTLY MORE UNSTABLE. THERE IS ALSO A SURFACE SYSTEM AND COLD FRONT. EXPECT SCATTERED SHOWERY PRECIP AGAIN...AND AIRMASS STABILITY IS BORDERLINE FOR TSTORM ACTIVITY...SO WILL LEAVE OUT MENTION. EXPECT A LITTLE COOLER TEMPS WITH MORE CLOUD COVER AND PRECIP SAT AND SO HAVE GONE BELOW MOS. WINDS WILL PICK UP BEHIND FRONTAL PASSAGE AND MAY BE CLOSE TO LAKE WIND ADVISORY CRITERIA FOR AWHILE DURING WEAK COOL ADVECTION PERIOD AS 850 MB WINDS ARE 20 KT. SIMONSEN .LONG TERM...SATURDAY NIGHT THROUGH THURSDAY... NORTHWEST FLOW ALOFT WILL GENERALLY CONTINUE THROUGH THE PERIOD. ONE SIGNIFICANT SHORTWAVE IS EXPECTED TO AFFECT MONTANA SATURDAY NIGHT AND SUNDAY WITH ANOTHER ONE POSSIBLE ON WEDNESDAY. THE WAVE FOR SATURDAY NIGHT AND SUNDAY IS CURRENTLY FORECASTED BY ALL OF THE MODELS TO TRACK THROUGH WESTERN AND SOUTHERN MONTANA. THIS WOULD KEEP THE BRUNT OF THE PRECIPITATION AWAY FROM THE FORECAST AREA. WILL ONLY MENTION A SLIGHT CHANCE OF SHOWERS FOR NOW. THE SYSTEM WILL BRING A COLD FRONT SOUTH SATURDAY NIGHT. WITH SURFACE HIGH MOVING IN BY SUNDAY NIGHT...SOME LOCATIONS ESPECIALLY IN THE NORTHEAST MAY SEE NEAR FREEZING TEMPERATURES FOR LOWS SUNDAY NIGHT. SHORTWAVE RIDGE WILL BRING A WARMING TREND INTO NORTHEAST MONTANA FOR MONDAY AND TUESDAY WITH DRY WEATHER. THE NEXT SHORTWAVE DROPS SOUTHEAST FROM BRITISH COLUMBIA TO IDAHO ON WEDNESDAY. THIS WILL BRING A COLD FRONT SOUTH ACROSS THE FORECAST AREA WHICH COULD PRODUCE A SHOWER OR TWO. WILL MENTION A SLIGHT CHANCE FOR MOST AREAS ON WEDNESDAY FOR NOW. HIGH PRESSURE MOVES IN FOR NEXT THURSDAY. FORRESTER && .AVIATION... ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND EARLY EVENING. NORTHWEST WINDS WILL DEVELOP THIS MORNING AND WILL INCREASE TO AROUND 15 KT BY AFTERNOON AT MOST TAF SITES. LOOK FOR SKIES TO CLEAR AND WINDS DIMINISH AFTER SUNSET WITH PATCHY FOG POSSIBLE. RAE && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WEATHER.GOV/GLASGOW mt AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GLASGOW MT 404 AM MDT THU SEP 4 2008 .SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH SATURDAY... THE LARGE SCALE PATTERN HAS THE JETSTREAM CONTINUING TO BE STRONGER AND FARTHER S THAN NORMAL FOR THIS TIME OF YEAR. THERE IS UPPER RIDGING OFF THE W COAST...WITH NE MT IN UPPER TROUGHING. MODELS HAVE THICKNESSES AND UPPER HEIGHTS BELOW NORMAL FOR THIS TIME OF YEAR TOO. THESE DON`T CHANGE MUCH...SO TEMPS TO STAY BELOW NORMAL IN THE SHORT TERM. THE UPPER TROUGH MOVING ENE ACROSS OUR AREA YESTERDAY AND LAST NIGHT DEVELOPED A CLOSED CIRCULATION OVER NE MT. THIS ENHANCED PRECIP IN OUR NE...BUT HAS NOW MOVED OUT OF OUR AREA. RUC HAD A GOOD HANDLE ON THE SYSTEM...BUT NOW ITS TOO SLOW COMPARED TO OTHER MODELS AND EXPECT ANY LINGERING SHOWER ACTIVITY IN OUR EXTREME NE TO BE DONE BY EARLY THIS MORN. QUITE A BIT OF PARTIAL CLEARING ELSEWHERE...MORE THAN EARLIER EXPECTED. SURFACE PRESSURE GRADIENTS BECOMING VERY WEAK AS WELL. THIS IS COMBINING WITH THE MOIST AIRMASS AT LOWER LEVELS TO CAUSE MOST OF THE CWA TO BE NEARLY SATURATED...TEMP/DWPOINT SPREADS GENERALLY LESS THAN 3F. THIS WILL MEAN PATCHES OF FOG ARE POSSIBLE AT MOST ANY LOCATION IN OUR CWA. THIS ESPECIALLY TRUE IN OUR NE WHERE LOW LEVELS MOST SATURATED FROM MOST SIGNIFICANT RAINFALL THAT JUST ENDED. ANOTHER AREA ALREADY WITH FOG IS NOW SEEN ON SATELLITE FOG LOOP ACROSS PARTS OF OUR SE...WIBAUX....DAWSON...AND RICHLAND COUNTIES. ALTHOUGH UPPER TROUGH LINGERS OVER THE AREA TODAY...THE MAIN DYNAMICS HAVE EXITED INTO ND AND MODELS INDICATE LITTLE SHORTWAVE ACTIVITY. ENOUGH MOISTURE AND INSTABILITY TO KEEP ISOLATED SHOWERS IN THE FORECAST FOR AFTERNOON AND EVE. WILL GO WITH NAM FORECAST SOUNDINGS...THAT ARE QUITE BORDERLINE FOR ANY TSTORM ACTIVITY...SO WILL LEAVE OUT MENTION. ONLY SLIGHT CHANGES IN UPPER PATTERN FOR FRI...BUT SOME DRYING OF THE AIRMASS WITH PRECIP WATER DOWN TO 0.50 OR LESS AND FORECAST SOUNDINGS ALL ABOVE ZERO. NO SIGNIFICANT SHORTWAVES IN SIGHT. THEREFORE EXPECT A LITTLE MORE SUNSHINE AND A LITTLE WARMER TEMPS FRI WITH LITTLE OR NO SHOWERS. THE NEXT MORE SIGNIFICANT SHORTWAVE ARRIVES IN NW FLOW SAT. MODELS SHOW BEST DYNAMICS AND MOISTURE IN OUR NE. AIRMASS AGAIN MOISTENS A BIT MORE AND BECOMES SLIGHTLY MORE UNSTABLE. THERE IS ALSO A SURFACE SYSTEM AND COLD FRONT. EXPECT SCATTERED SHOWERY PRECIP AGAIN...AND AIRMASS STABILITY IS BORDERLINE FOR TSTORM ACTIVITY...SO WILL LEAVE OUT MENTION. EXPECT A LITTLE COOLER TEMPS WITH MORE CLOUD COVER AND PRECIP SAT AND SO HAVE GONE BELOW MOS. WINDS WILL PICK UP BEHIND FRONTAL PASSAGE AND MAY BE CLOSE TO LAKE WIND ADVISORY CRITERIA FOR AWHILE DURING WEAK COOL ADVECTION PERIOD AS 850 MB WINDS ARE 20 KT. SIMONSEN .LONG TERM...SATURDAY NIGHT THROUGH THURSDAY... NORTHWEST FLOW ALOFT WILL GENERALLY CONTINUE THROUGH THE PERIOD. ONE SIGNIFICANT SHORTWAVE IS EXPECTED TO AFFECT MONTANA SATURDAY NIGHT AND SUNDAY WITH ANOTHER ONE POSSIBLE ON WEDNESDAY. THE WAVE FOR SATURDAY NIGHT AND SUNDAY IS CURRENTLY FORECASTED BY ALL OF THE MODELS TO TRACK THROUGH WESTERN AND SOUTHERN MONTANA. THIS WOULD KEEP THE BRUNT OF THE PRECIPITATION AWAY FROM THE FORECAST AREA. WILL ONLY MENTION A SLIGHT CHANCE OF SHOWERS FOR NOW. THE SYSTEM WILL BRING A COLD FRONT SOUTH SATURDAY NIGHT. WITH SURFACE HIGH MOVING IN BY SUNDAY NIGHT...SOME LOCATIONS ESPECIALLY IN THE NORTHEAST MAY SEE NEAR FREEZING TEMPERATURES FOR LOWS SUNDAY NIGHT. SHORTWAVE RIDGE WILL BRING A WARMING TREND INTO NORTHEAST MONTANA FOR MONDAY AND TUESDAY WITH DRY WEATHER. THE NEXT SHORTWAVE DROPS SOUTHEAST FROM BRITISH COLUMBIA TO IDAHO ON WEDNESDAY. THIS WILL BRING A COLD FRONT SOUTH ACROSS THE FORECAST AREA WHICH COULD PRODUCE A SHOWER OR TWO. WILL MENTION A SLIGHT CHANCE FOR MOST AREAS ON WEDNESDAY FOR NOW. HIGH PRESSURE MOVES IN FOR NEXT THURSDAY. FORRESTER && .AVIATION... SHOWERS HAVE CLEARED NORTHEAST MONTANA FOR THE TIME BEING. SKIES HAVE CLEARED WHICH HAS ALLOWED AREAS OF FOG TO DEVELOP. MAY SEE PERIODS OF IFR CONDITIONS WHERE FOG DOES OCCUR THIS MORNING. WHILE VFR CONDITIONS WILL PREVAIL MOST OF THE TIME FOR TODAY AND TONIGHT. ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND EARLY EVENING. NORTHWEST WINDS WILL DEVELOP THIS MORNING AND WILL INCREASE TO AROUND 15 KT BY AFTERNOON AT MOST TAF SITES. LOOK FOR SKIES TO CLEAR AND WINDS DIMINISH AFTER SUNSET WITH PATCHY FOG POSSIBLE. && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WEATHER.GOV/GLASGOW mt AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BILLINGS MT 332 AM MDT THU SEP 4 2008 .SHORT TERM...VALID FOR TDY AND FRI... COUPLE OF SHORTWAVES WILL AFFECT THE AREA TODAY. FIRST IS ENERGY CURRENTLY SAGGING INTO NORTHEAST MONTANA ON WESTERN FLANK OF DEEPER TROF IN THE DAKOTAS. AS EVENING SHIFT NOTED ONLY Q-VECTOR DIVERGENCE IN OUR EAST TODAY DESPITE THIS WAVE...LIKELY DUE TO THE COLD ADVECTION TAKING PLACE. NONETHELESS...TEMPS ALOFT ARE FAIRLY COLD...ON THE ORDER OF -20C AT 500MB. 00Z TFX SOUNDING SHOWED A RELATIVELY MOIST/UNSTABLE PROFILE FROM 700-500MB. ALSO...SURFACE DEW POINTS ARE REASONABLY HIGH IN THE LOWER 40S. GFS SEEMS TO HAVE BETTER HANDLE ON THE LOW LEVEL MOISTURE...AND SHOWS AFTERNOON CAPES OF A FEW HUNDRED J/KG FROM MLS TO BHK...LESS FURTHER WEST. WITH ALL OF THIS IN MIND WILL KEEP SCATTERED POPS GOING...THOUGH HAVE LOWERED MORNING COVERAGE TO ISOLATED GIVEN LITTLE IS GOING ON NOW AND WE WILL HAVE TO WAIT FOR DIURNAL HEATING. NEXT SHORTWAVE DROPPING QUICKLY THROUGH BRITISH COLUMBIA COULD PROVE TO BE A LITTLE MORE INTERESTING. CLOUD COVER ALREADY ENHANCING FROM SOUTHERN BC ALONG THE MT/ID BORDER...AND THIS MATCHES WELL WITH QG FORCING ADVERTISED BY THE MODELS. HAVE RAISED MTN POPS A BIT MORE...AND SOME -SHSN POSSIBLE AS 700MB TEMPS SHOULD FALL TO A LITTLE BELOW ZERO TODAY. LOW TO MID LEVEL FLOW TURNS N-NE LATE TODAY AND THIS EVENING AS THE WAVE MOVES THROUGH...AND THIS IS ALREADY HAPPENING UP IN CANADA PER RUC ANALYSIS. THIS SHOULD FOCUS THE PCPN ALONG THE NORTHERN SLOPES OF THE BEARTOOTHS AND BIG HORNS. HAVE RAISED POPS SOME IN THIS AREA...INCLUDING THE FOOTHILLS FROM NYE TO RED LODGE WHICH SHOULD BECOME FAVORED BETWEEN 21-06Z...PER UPSLOPE AND GREATEST UPPER SUPPORT. 00Z 700MB ANALYSIS SHOWED 700MB TEMP OF -6C IN SOUTHERN BC...AND AS WE TAP INTO THIS AIR THINK SOME SNOW IS A GOOD BET IN ALONG THE NORTH SLOPES ABOVE RED LODGE AND NYE. HAVE GIVEN COLE CREEK AN INCH OF SNOW TONIGHT...AND WILL NEED TO MONITOR THIS AS THIS SYSTEM EVOLVES TODAY. THINGS WILL QUIET DOWN TONIGHT WITH LOSS OF DAYTIME HEATING AND AS WAVE MOVES TO OUR SOUTH. FRIDAY SHOULD BE A MOSTLY DRY DAY WITH A DOWNSLOPE FLOW SETTING UP BETWEEN SHORTWAVES. GFS AND 06Z NAM SHOW PERIOD OF MOIST WARM ADVECTION AHEAD OF NEXT CLIPPER DEVELOPING LATE FRIDAY AND FRIDAY NIGHT. WILL KEEP MENTION OF SHOWERS GOING FRIDAY AFTERNOON IN THE WEST AND FRIDAY NIGHT ACROSS THE AREA TO ACCOUNT FOR THIS...THOUGH HAVE LOWERED POPS A TAD ESPECIALLY WESTERN PARTS DUE TO THE DOWNSLOPE FLOW. AIRMASS WILL BE QUITE A BIT MORE STABLE...AND ANY PCPN WILL BE LIGHT. BETTER CHANCE OF PCPN WILL HOLD OFF TIL SATURDAY...SEE EXTENDED DISCUSSION FOR THAT. BELOW NORMAL TEMPS WILL CONTINUE THE NEXT TWO DAYS. TODAY SHOULD BE COOLER THAN WEDNESDAY AS COOL CANADIAN SURFACE RIDGE BLEEDS SOUTHWARD BEHIND ENERGY IN NE MONTANA. 850MB TEMPS FALL TO THE LOWER TEENS. FRIDAY SHOULD BE WARMER WITH WEST FLOW AND A BIT OF RIDGING...BUT INCREASING CLOUD COVER DURING THE AFTERNOON COULD HOLD THINGS BACK SOME. SHOULD GET CLOSE TO 70F ON FRIDAY. JKL .LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED... COOL AND UNSETTLED LOOKS THE WAY TO GO FOR THE WEEKEND. MODELS HAVE BEEN COMING MORE IN LINE ON THE NEXT MAIN WEATHER MAKER FOR THE FORECAST AREA. THE FALL WEATHER PATTERN COULD TURN WINTRY IN THE HIGHER TERRAIN SATURDAY NIGHT AND SUNDAY AS STRONG ENERGY DIGS OUT A DEEPENING TROUGH OVER THE NORTHERN PLAINS AND ROCKIES. BOTH THE GFS AND WRF WERE COMING IN DEEPER WITH THE UPPER TROUGH AND FARTHER WEST WITH ENERGY DIGGING INTO THE STATE. THIS TREND SHOULD SET UP A STRONG FRONTOGENESIS BAND OVER SOUTH CENTRAL MONTANA AS A REINFORCING SHOT OF COOLING AIR SLIPS INTO THE AREA SATURDAY. DEEP UPSLOPE FLOW DEVELOPS WITH DYNAMIC ENERGY DIVING TOWARD SOUTHWEST MONTANA. BUMPED POPS UP QUITE A BIT FOR SATURDAY AFTERNOON THROUGH SUNDAY...MAINLY SATURDAY NIGHT AND SUNDAY. LOWERED TEMPERATURES FOR SUNDAY AS WELL...AND MAY NEED TO GO COOLER. 06Z WRF WOULD SUPPORT HIGHS IN THE 50S SUNDAY WITH LIKELY RAIN ALONG THE EAST SLOPES EAST TOWARD A LINE FROM RYEGATE TO BILLINGS AND SHERIDAN. GOT MY FOOT IN THE DOOR BY RAISING POPS INTO THE HIGH SCATTERED CATEGORY AND WILL USE THE NEXT COUPLE OF MODEL RUNS TO FINE TUNE THINGS. 700MB TEMPERATURES FALL TO AROUND -4C BY EARLY SUNDAY...SO THE HIGHER TERRAIN LOOKS TO HAVE A SHOT OF SNOW WITH THIS IN THE MOUNTAINS ABOVE NYE AND RED LODGE. WILL ISSUE AN HWO FOR THE POTENTIAL SNOW IN THE HIGH COUNTRY AND COOL AND WET AGAIN FOR THE PLAINS OF SOUTH CENTRAL MONTANA SATURDAY NIGHT AND SUNDAY. DRIER WEATHER SHOULD MOVE IN SUNDAY NIGHT AND MONDAY AS THE TROUGH MOVES EAST AND IS REPLACED BY FLAT RIDGING. THE DEEP UPSLOPE FLOW GOES AWAY AND MAKES ROOM FOR DOWNSLOPE AND THIS SHOULD PROVIDE OUR BEST SHOT OF GETTING TEMPERATURES ABOVE 70 DEGREES THIS MONTH. READINGS IN THE MID TO UPPER 70S LOOK LIKE A GOOD BET FOR TUESDAY. MODELS THEN DIG THE NEXT UPSTREAM TROUGH INTO NORTHERN IDAHO WEDNESDAY. THIS WILL SEND ANOTHER STRONG COLD FRONT THROUGH WEDNESDAY AND WEDNESDAY NIGHT. COULD BE ANOTHER GOOD SHOT OF PRECIPITATION OVER SOUTH CENTRAL MONTANA AS THE MID LEVEL TROUGH CUTS OFF A LOW OVER IDAHO. FRONTOGENESIS BAND SHOULD SET UP SOMEWHERE OVER SOUTH CENTRAL MONTANA TUESDAY NIGHT INTO WEDNESDAY NIGHT FOR A SHOT OF PRECIPITATION. RAISED POPS FOR THIS. HUMPHREY && .AVIATION... AREAS OF MORNING FOG WILL IMPACT BHK. CONDITIONS WILL BE OCCASIONALLY LIFR AT BHK THIS MORNING IN PATCHY DENSE FOG...OTHERWISE CONDITIONS WILL BE VFR ELSEWHERE. A DISTURBANCE WILL MOVE THROUGH THE AREA TODAY AND GENERATE ANOTHER ROUND OF SCATTERED SHOWERS WITH ISOLATED THUNDERSTORMS. THE STRONGER SHOWERS WILL PRODUCE LOCAL MVFR CONDITIONS. THE BEST CHANCE FOR SHOWERS WILL BE OVER THE MOUNTAINS AND SOUTH OF A LINE FROM KLVM TO KBIL TO KMLS. THE MOUNTAINS WILL BE FREQUENTLY OBSCURED TODAY WITH OCCASIONAL SHOWERS...ESPECIALLY THIS AFTERNOON. THE SHOWERS WILL DECREASE FROM NORTH OF SOUTH TONIGHT. HUMPHREY && .PRELIMINARY POINT TEMP/POPS... TDY FRI SAT SUN MON TUE WED ------------------------------------------------------- BIL 064 045/068 048/069 048/063 045/071 048/078 052/072 3/W 21/B 22/W 55/W 20/U 00/B 22/W LVM 064 036/068 040/066 042/062 038/071 040/078 043/069 4/W 22/W 22/W 45/W 20/B 00/B 22/W HDN 065 042/071 047/070 047/065 044/073 047/080 049/077 3/T 21/B 22/W 55/W 20/B 00/B 02/W MLS 066 046/070 048/070 048/064 044/071 046/076 050/073 3/T 21/B 32/W 22/W 20/U 00/B 00/B 4BQ 064 042/069 046/070 047/065 044/071 046/077 050/073 4/T 32/W 32/W 43/W 20/U 00/B 00/B BHK 064 043/069 043/065 043/063 043/070 045/075 048/073 3/T 22/W 32/W 22/W 20/B 00/U 00/B SHR 064 039/068 043/069 044/064 040/070 042/078 044/071 4/T 31/B 22/W 55/W 30/U 00/B 02/W && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$ WEATHER.GOV/BILLINGS mt AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GLASGOW MT 921 PM MDT WED SEP 3 2008 .SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT... UPPER TROUGH MOVING SLOWLY E ACROSS THE AREA TONIGHT WITH A SEPARATE CIRCULATION DEVELOPING OVER OUR AREA. RUC HAS THIS WELL- DEPICTED WHICH IS SEEN WELL ON 88D REFLECTIVELY LOOPS. RUC SLOWS THIS SYSTEM DOWN AND INTENSIFIES IT AS A RESULT. THIS GENERATES WIDESPREAD SHOWERS THAT LAST THRU THE NIGHT IN OUR NE. WILL GO WITH THAT SCENARIO AND RE-LOCATE OUR HIGHEST POPS FROM THE SE THIS EVE TO NE. RUC SHOWS QPF UP TO 0.45. ELSEWHERE...THE AIRMASS REMAINS MOIST AND UNSTABLE WITH A WEAK SHORTWAVE OR TWO TO KEEP ISOLATED SHOWERS IN THE FORECAST THRU THE NIGHT. ISOLATED TSTORMS HAVE DIED IN THE LAST HOUR...SO WILL DROP MENTION. LOCATIONS IN OUR NE ALREADY HAVE NARROW TEMP/DEW POINT SPREADS DUE TO EXTENSIVE PRECIP...BUT NOT EXPECTING ANY CLEARING TO AID FOG FORMATION. WITH 8 PM TEMPS ALREADY DOWN INTO THE UPPER 40S AND LOWER 50S MOST AREAS...FORECAST LOWS LOOK REASONABLE. SIMONSEN PREVIOUS SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH FRIDAY...UNSETTLED NORTHWEST FLOW ALOFT WILL CONTINUE TO DOMINATE THE SHORT TERM AS PERIODIC SHORTWAVE TROFS DROP SOUTHEAST ACROSS THE CANADIAN ROCKIES. A RATHER VIGOROUS TROF PRESENTLY OVER CENTRAL MONTANA HAS BEEN GENERATING A BAND OF MOSTLY LIGHT RAIN ACROSS THE SOUTHEASTERN HALF THE CWA WITH MORE SHOWERY CONVECTION NOTED TO THE WEST UNDER A COLD POCKET. MODELS CONTINUE TO INDICATE PRECIPITATION CHANCES INCREASING OVERNIGHT ACROSS OUR EASTERN ZONES AS A REINFORCING S/W TROF DIGS INTO THE MAIN TROF/S BASE. THIS PROCESS SHOULD DRIVE SOME APPRECIABLE DIVERGENCE ALOFT JUST DOWNSTREAM OF THE TROF AXIS...THOUGH QPF TOTALS WERE KEPT ON THE LOW END AS THE BEST FORCING LOOKS BETTER JUST ACROSS THE BORDER INTO NORTH DAKOTA. INHERITED POPS ADDRESSED THIS SOLUTION RATHER WELL...SO ONLY MINIMAL ADJUSTMENTS WERE NECESSARY HERE. A STRONGER COLD POCKET ASSOCIATED WITH YET ANOTHER S/W TROF ARRIVES THURSDAY MORNING AND BY THE AFTERNOON WOULD EXPECT QUITE A FEW CONVECTIVE ELEMENTS TO UNFOLD...ESPECIALLY IN OUR EASTERN ZONES WHERE THE TIMING OF THIS WAVE WILL BETTER COINCIDE WITH MAX HEATING. ALBEIT MARGINAL...THE GFS IS RATHER BULLISH WITH CAPE COMPARED TO THE NAM...THOUGH A FEW SMALL HAILERS ARE NOT OUT OF THE QUESTION GIVEN LOW WBZ HEIGHTS. FOR NOW THE THREAT LOOKS TOO LIMITED AND NOT WORTH INCLUDING IN THE FORECAST. HIGH PRESSURE MEANWHILE WILL BEGIN NUDGING INTO THE REGION DURING THIS TIME TIGHTENING THE GRADIENT FLOW SOME. VARIOUS FORECAST SOUNDINGS REVEAL WINDS 20-25 MPH THROUGHOUT THE MIXING LAYER...THEREFORE A LAKE WIND ADVISORY MAY BECOME NECESSARY UPON ADDITIONAL INSPECTION. BY THURSDAY NIGHT THE FLOW STABILIZES OUT ALLOWING FOR A PLEASANT DAY ON FRIDAY AS SURFACE HIGH PRESSURE GLIDES ACROSS CENTRAL MONTANA AND INTO WYOMING. MCZ .LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY... NOT MUCH CHANGE TO THE LONG TERM FORECAST. MODELS SEEM TO BE IN GOOD AGREEMENT. JET STREAM WILL CONTINUE TO WEAKEN AND BRING DISTURBANCE IN A LITTLE EARLIER ON SUNDAY AND INTO MONDAY. FLOW WILL BEGIN TO FLATTEN OUT TOWARD THE END OF THE FORECAST PERIOD AND BRING IN A DRIER AND WARMER WESTERLY FLOW. SHALLENBERGER PREVIOUS LONG TERM DISCUSSION...THE PERIOD BEGINS WITH THE JETSTREAM REMAINING STRONGER AND FARTHER S THAN NORMAL FOR THIS TIME OF YEAR. THE PATTERN BECOMES MORE AMPLIFIED THIS WEEKEND WITH A CLOSED HIGH CENTER OFF THE PACIFIC NW COAST...AND A RATHER DEEP UPPER LOW COMPLEX EXTENDING FROM N OF HUDSON BAY TO THE UPPER MIDWEST STATES. NE MT IS ALSO IN THE CYCLONIC UPPER FLOW WITH THIS LOW PRESSURE ALOFT AND IT APPEARS THERE WILL BE ONE OR TWO SHORTWAVES TO EFFECT OUR AREA THIS WEEKEND IN THIS FLOW. WOULD EXPECT ISOLATED-TYPE SHOWERS FOR 3 OR 4 12HR FORECAST PERIODS WHICH CURRENT FORECAST HAS...WITH SHORTWAVES OF MODERATE INTENSITY AT BEST. THICKNESSES REMAIN LOW FOR THE TIME OF THE YEAR IN THE UPPER 540S TO LOWER 550S DM ON AVERAGE. SURFACE HIGH PRESSURE FROM THE NW SUN NIGHT BRINGS PARTIAL CLEARING AND POTENTIAL FOR SOME OF THE CHILLIEST LOWS SINCE MAY...LOTS OF 30S FOR LOWS...BUT ONLY SPOTTY LIGHT FROST. SHORTWAVE ENERGY FROM UPPER RIDGING ARRIVES FROM THE MAIN UPPER HIGH MON AND TUE...WHILE THE JETSTREAM WEAKENS AND TURNS W. THIS ALLOWS FOR TEMPS TO WARM BACK TO NORMAL. ANOTHER SHORTWAVE FROM THE NW ARRIVES WED. MODELS DON`T SHOW MUCH MOISTURE WITH IT...BUT WILL LEAD TO COOLING AGAIN. OVERALL...MODELS IN DECENT AGREEMENT WITH THE LONG TERM PATTERN. SIMONSEN && .AVIATION... VFR CONDITIONS ARE EXPECTED TO PREDOMINATE THRU THE NIGHT AND ON THURSDAY. ISOLATED TO SCATTERED SHOWERS THRU THIS TIME MAY PROVIDE SOME BRIEF PERIODS OF MVFR TO IFR CONDITIONS. KGDV COULD POSSIBLY EXPERIENCE A THUNDERSTORM THIS EVENING...OTHERWISE ONLY SHOWERS ARE EXPECTED. THUNDERSTORMS WILL ONCE AGAIN BE POSSIBLE WITH SHOWERS THURSDAY AFTERNOON AND EARLY EVENING. WIND WILL BE VARIABLE AT LESS THAN 10 KT FOR MOST OF TONIGHT BEFORE BECOMING NORTH NORTHWEST EARLY THURSDAY MORNING. BY AFTERNOON SPEEDS WILL INCREASE TO AROUND 15 KT AT MOST TAF SITES. && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WEATHER.GOV/GLASGOW mt AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HASTINGS NE 1229 PM CDT WED SEP 3 2008 .AVIATION...18Z TAF. VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. SURFACE HIGH PRESSURE WILL BE THE DOMINATE WEATHER FEATURE. WINDS WILL BE FROM A NORTHEAST TO EASTERLY DIRECTION PRIOR TO BECOMING VARIABLE TONIGHT. CLOUD COVER WILL BE RATHER LIMITED IN THE DRY AIRMASS. && PREV DISCUSSION... /ISSUED 350 AM CDT WED SEP 3 2008/ DISCUSSION...00Z UPPER AIR OBSERVATIONS SHOW GENERALLY ZONAL FLOW ACROSS THE WESTERN HALF OF THE CONUS WITH A BROAD TROUGH OVER THE NORTHERN PLAINS/PAC NW. ACROSS THE EAST...THINGS A BIT MORE COMPLEX WITH REMNANTS OF GUSTAV NEAR THE GULF AND ANOTHER AREA OF LOW PRESSURE JUST OFF THE NORTHEAST COAST. CURRENT SATELLITE IMAGERY SHOWS GUSTAV HAS NOT MOVED MUCH...AND IS STILL CENTERED NEAR THE AK/LA/TX BORDERS. THIS SLOW MOVEMENT DUE IN PART TO THE LOW LEVEL PATTERN...WHICH SHOWS A COLD FRONT DRAPED FROM THE GREAT LAKES REGION SOUTH INTO NORTHERN TEXAS..WITH A LARGE AREA OF HIGH PRESSURE BUILDING INTO THE CENTRAL CONUS BEHIND THE FRONT. ACROSS OUR CWA...SHARP GRADIENT EXISTS WITH CLOUD COVER...WITH THE NORTHWEST BEING CLEAR AND THE SOUTHEAST SEEING MOSTLY CLOUDY SKIES. AN AREA OF SHOWERS HAS DEVELOPED JUST TO THE SOUTHEAST OF THE CWA ASSOCIATED WITH A NARROW WEAK AREA OF LOW/MID LVL FRONTOGENESIS/ISENTROPIC LIFT. NAM/RUC HAVE GOOD HANDLE ON CURRENT SHOWER ACTIVITY...AND BOTH SHOW FORCING GRADUALLY DECREASING WITH TIME WITH MOST OF THE PRECIPITATION STAYING JUST OUT OF THE CWA...SO KEPT DRY FORECAST GOING EXCEPT FOR FAR SOUTHEAST CORNER. ANY SHOWERS WHICH MAY CREEP INTO THE CWA THIS MORNING WOULD AMOUNT TO LITTLE TO NOTHING. FOR THE REST OF TODAY AND THROUGH THURSDAY...DRY WEATHER EXPECTED ACROSS THE ENTIRE CWA. MODELS IN GOOD AGREEMENT SHOWING THE UPPER LEVEL PATTERN OVER THE CWA BECOMING MORE SOUTHWESTERLY AS A TROUGH MOVES EAST INTO NORTHERN ROCKIES/PLAINS. WHILE GUSTAV SPENDS A GOOD CHUNK OF THE DAY SPINNING TO THE SOUTH...EVENTUALLY IT BECOMES PHASED INTO THE MAIN FLOW AND SHIFTS TO THE NORTH/NORTHEAST. MODELS CONTINUE TO AGREE...SHOWING THE BULK OF THE FORCING AND PRECIPITATION STAYING TO OUR EAST...HAVING A GREATER IMPACT ON KANSAS/MISSOURI/IOWA BEFORE SHIFTING NEAR THE GREAT LAKES. LOOKING AT THE SURFACE...MAIN PLAYER FOR OUR AREA WILL LIE WITH THE AREA OF HIGH PRESSURE CURRENTLY BUILDING IN BEHIND THE FRONT. CENTER OF HIGH EXPECTED TO LIE ACROSS THE DAKOTAS TODAY...BEFORE GRADUALLY SHIFTING EAST TONIGHT AND INTO THURSDAY. LIGHT NORTHERLY/EASTERLY WINDS EXPECTED...WITH CONTINUED BELOW NORMAL HIGH TEMPERATURES. AFTERNOON HIGHS FOR TODAY EXPECTED TO BE NEAR 70 DEGREES...WITH THURSDAY JUST A TOUCH WARMER AS THAT SURFACE HIGH SHIFTS EAST...REACHING INTO THE LOWER/MID 70S. OVERALL...VERY PLEASANT COUPLE OF DAYS EXPECTED. NEXT CHANGE ACROSS THE CWA EXPECTED TO ARRIVE LATE THURSDAY NIGHT/EARLY FRIDAY MORNING WITH A CHANCE FOR PRECIPITATION. UPPER LEVEL PATTERN SETS UP SO THAT A GOOD PORTION OF THE CONUS LIES UNDER THE INFLUENCE OF A BROAD TROUGH...WITH THE AXIS LYING THROUGH THE PLAINS. A SMALLER DISTURBANCE PASSING THROUGH THE FLOW WORKS ITS WAY EAST...AND LOOKS TO CROSS OVER THE CWA. ALONG WITH THE DISTURBANCE...A WEAK SURFACE FRONT PUSHES SOUTH INTO THE CWA...WHICH ALSO SITS IN A FAVORABLE POSITION FOR HELP FROM AN UPPER LEVEL JET STREAK MOVING OVERHEAD. DID INCREASE POPS ACROSS THE CWA...WITH BEST CHANCES COMING DURING THE DAYTIME HOURS ON FRIDAY. ALSO ADJUSTED TEMPS FOR FRIDAY DOWN A FEW DEGREES WITH THE CHANCES FOR PRECIP AND PLENTY OF CLOUD COVER AROUND...AND AM EXPECTING HIGHS TO STRUGGLE TO HIT 70. AS FAR AS THUNDERSTORM CHANCES...INSTABILITY NOT OVERLY IMPRESSIVE AT ANY LEVEL ACROSS THE CWA...BUT SOUTHERN AREAS ARE A BIT BETTER...SO TRENDED THE NORTHERN CWA DOWN TO JUST AN ISOLATED THUNDER MENTION. PRECIPITATION CHANCES LOOK TO LINGER ON THOUGH THE WEEKEND AND INTO EARLY NEXT WEEK...AS ADDITIONAL SHORTWAVE DISTURBANCES WORK INTO THE REGION. NO ADJUSTMENTS CHANGES TO POPS...AS MODELS STILL DIFFER WITH TIMING OF THESE DISTURBANCES AND ASSOCIATED PRECIP. WITH NO SIGNIFICANT CHANGES TO THE OVERALL PATTERN...LITTLE CHANGES EXPECTED IN REGARD TO TEMPERATURES...WITH BELOW NORMAL HIGHS STAYING IN THE 70S. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HASTINGS NE 541 AM CDT WED SEP 3 2008 .AVIATION...12Z KGRI TAF. VFR CONDITIONS THROUGHOUT THE TAF. WIND MAY PICK UP A BIT FROM THE EAST FOR A PERIOD DURING THE DAY WEDNESDAY. SOME SCATTERED MID-LEVEL SKY COVER POSSIBLE TOWARD THE VERY END OF THE FORECAST...BUT NO CHANGE IN CATEGORY EXPECTED. && .PREV DISCUSSION... /ISSUED 350 AM CDT WED SEP 3 2008/ DISCUSSION...00Z UPPER AIR OBSERVATIONS SHOW GENERALLY ZONAL FLOW ACROSS THE WESTERN HALF OF THE CONUS WITH A BROAD TROUGH OVER THE NORTHERN PLAINS/PAC NW. ACROSS THE EAST...THINGS A BIT MORE COMPLEX WITH REMNANTS OF GUSTAV NEAR THE GULF AND ANOTHER AREA OF LOW PRESSURE JUST OFF THE NORTHEAST COAST. CURRENT SATELLITE IMAGERY SHOWS GUSTAV HAS NOT MOVED MUCH...AND IS STILL CENTERED NEAR THE AK/LA/TX BORDERS. THIS SLOW MOVEMENT DUE IN PART TO THE LOW LEVEL PATTERN...WHICH SHOWS A COLD FRONT DRAPED FROM THE GREAT LAKES REGION SOUTH INTO NORTHERN TEXAS..WITH A LARGE AREA OF HIGH PRESSURE BUILDING INTO THE CENTRAL CONUS BEHIND THE FRONT. ACROSS OUR CWA...SHARP GRADIENT EXISTS WITH CLOUD COVER...WITH THE NORTHWEST BEING CLEAR AND THE SOUTHEAST SEEING MOSTLY CLOUDY SKIES. AN AREA OF SHOWERS HAS DEVELOPED JUST TO THE SOUTHEAST OF THE CWA ASSOCIATED WITH A NARROW WEAK AREA OF LOW/MID LVL FRONTOGENESIS/ISENTROPIC LIFT. NAM/RUC HAVE GOOD HANDLE ON CURRENT SHOWER ACTIVITY...AND BOTH SHOW FORCING GRADUALLY DECREASING WITH TIME WITH MOST OF THE PRECIPITATION STAYING JUST OUT OF THE CWA...SO KEPT DRY FORECAST GOING EXCEPT FOR FAR SOUTHEAST CORNER. ANY SHOWERS WHICH MAY CREEP INTO THE CWA THIS MORNING WOULD AMOUNT TO LITTLE TO NOTHING. FOR THE REST OF TODAY AND THROUGH THURSDAY...DRY WEATHER EXPECTED ACROSS THE ENTIRE CWA. MODELS IN GOOD AGREEMENT SHOWING THE UPPER LEVEL PATTERN OVER THE CWA BECOMING MORE SOUTHWESTERLY AS A TROUGH MOVES EAST INTO NORTHERN ROCKIES/PLAINS. WHILE GUSTAV SPENDS A GOOD CHUNK OF THE DAY SPINNING TO THE SOUTH...EVENTUALLY IT BECOMES PHASED INTO THE MAIN FLOW AND SHIFTS TO THE NORTH/NORTHEAST. MODELS CONTINUE TO AGREE...SHOWING THE BULK OF THE FORCING AND PRECIPITATION STAYING TO OUR EAST...HAVING A GREATER IMPACT ON KANSAS/MISSOURI/IOWA BEFORE SHIFTING NEAR THE GREAT LAKES. LOOKING AT THE SURFACE...MAIN PLAYER FOR OUR AREA WILL LIE WITH THE AREA OF HIGH PRESSURE CURRENTLY BUILDING IN BEHIND THE FRONT. CENTER OF HIGH EXPECTED TO LIE ACROSS THE DAKOTAS TODAY...BEFORE GRADUALLY SHIFTING EAST TONIGHT AND INTO THURSDAY. LIGHT NORTHERLY/EASTERLY WINDS EXPECTED...WITH CONTINUED BELOW NORMAL HIGH TEMPERATURES. AFTERNOON HIGHS FOR TODAY EXPECTED TO BE NEAR 70 DEGREES...WITH THURSDAY JUST A TOUCH WARMER AS THAT SURFACE HIGH SHIFTS EAST...REACHING INTO THE LOWER/MID 70S. OVERALL...VERY PLEASANT COUPLE OF DAYS EXPECTED. NEXT CHANGE ACROSS THE CWA EXPECTED TO ARRIVE LATE THURSDAY NIGHT/EARLY FRIDAY MORNING WITH A CHANCE FOR PRECIPITATION. UPPER LEVEL PATTERN SETS UP SO THAT A GOOD PORTION OF THE CONUS LIES UNDER THE INFLUENCE OF A BROAD TROUGH...WITH THE AXIS LYING THROUGH THE PLAINS. A SMALLER DISTURBANCE PASSING THROUGH THE FLOW WORKS ITS WAY EAST...AND LOOKS TO CROSS OVER THE CWA. ALONG WITH THE DISTURBANCE...A WEAK SURFACE FRONT PUSHES SOUTH INTO THE CWA...WHICH ALSO SITS IN A FAVORABLE POSITION FOR HELP FROM AN UPPER LEVEL JET STREAK MOVING OVERHEAD. DID INCREASE POPS ACROSS THE CWA...WITH BEST CHANCES COMING DURING THE DAYTIME HOURS ON FRIDAY. ALSO ADJUSTED TEMPS FOR FRIDAY DOWN A FEW DEGREES WITH THE CHANCES FOR PRECIP AND PLENTY OF CLOUD COVER AROUND...AND AM EXPECTING HIGHS TO STRUGGLE TO HIT 70. AS FAR AS THUNDERSTORM CHANCES...INSTABILITY NOT OVERLY IMPRESSIVE AT ANY LEVEL ACROSS THE CWA...BUT SOUTHERN AREAS ARE A BIT BETTER...SO TRENDED THE NORTHERN CWA DOWN TO JUST AN ISOLATED THUNDER MENTION. PRECIPITATION CHANCES LOOK TO LINGER ON THOUGH THE WEEKEND AND INTO EARLY NEXT WEEK...AS ADDITIONAL SHORTWAVE DISTURBANCES WORK INTO THE REGION. NO ADJUSTMENTS CHANGES TO POPS...AS MODELS STILL DIFFER WITH TIMING OF THESE DISTURBANCES AND ASSOCIATED PRECIP. WITH NO SIGNIFICANT CHANGES TO THE OVERALL PATTERN...LITTLE CHANGES EXPECTED IN REGARD TO TEMPERATURES...WITH BELOW NORMAL HIGHS STAYING IN THE 70S. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ AVIATION...HEINLEIN ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HASTINGS NE 350 AM CDT WED SEP 3 2008 .DISCUSSION...00Z UPPER AIR OBSERVATIONS SHOW GENERALLY ZONAL FLOW ACROSS THE WESTERN HALF OF THE CONUS WITH A BROAD TROUGH OVER THE NORTHERN PLAINS/PAC NW. ACROSS THE EAST...THINGS A BIT MORE COMPLEX WITH REMNANTS OF GUSTAV NEAR THE GULF AND ANOTHER AREA OF LOW PRESSURE JUST OFF THE NORTHEAST COAST. CURRENT SATELLITE IMAGERY SHOWS GUSTAV HAS NOT MOVED MUCH...AND IS STILL CENTERED NEAR THE AK/LA/TX BORDERS. THIS SLOW MOVEMENT DUE IN PART TO THE LOW LEVEL PATTERN...WHICH SHOWS A COLD FRONT DRAPED FROM THE GREAT LAKES REGION SOUTH INTO NORTHERN TEXAS..WITH A LARGE AREA OF HIGH PRESSURE BUILDING INTO THE CENTRAL CONUS BEHIND THE FRONT. ACROSS OUR CWA...SHARP GRADIENT EXISTS WITH CLOUD COVER...WITH THE NORTHWEST BEING CLEAR AND THE SOUTHEAST SEEING MOSTLY CLOUDY SKIES. AN AREA OF SHOWERS HAS DEVELOPED JUST TO THE SOUTHEAST OF THE CWA ASSOCIATED WITH A NARROW WEAK AREA OF LOW/MID LVL FRONTOGENESIS/ISENTROPIC LIFT. NAM/RUC HAVE GOOD HANDLE ON CURRENT SHOWER ACTIVITY...AND BOTH SHOW FORCING GRADUALLY DECREASING WITH TIME WITH MOST OF THE PRECIPITATION STAYING JUST OUT OF THE CWA...SO KEPT DRY FORECAST GOING EXCEPT FOR FAR SOUTHEAST CORNER. ANY SHOWERS WHICH MAY CREEP INTO THE CWA THIS MORNING WOULD AMOUNT TO LITTLE TO NOTHING. FOR THE REST OF TODAY AND THROUGH THURSDAY...DRY WEATHER EXPECTED ACROSS THE ENTIRE CWA. MODELS IN GOOD AGREEMENT SHOWING THE UPPER LEVEL PATTERN OVER THE CWA BECOMING MORE SOUTHWESTERLY AS A TROUGH MOVES EAST INTO NORTHERN ROCKIES/PLAINS. WHILE GUSTAV SPENDS A GOOD CHUNK OF THE DAY SPINNING TO THE SOUTH...EVENTUALLY IT BECOMES PHASED INTO THE MAIN FLOW AND SHIFTS TO THE NORTH/NORTHEAST. MODELS CONTINUE TO AGREE...SHOWING THE BULK OF THE FORCING AND PRECIPITATION STAYING TO OUR EAST...HAVING A GREATER IMPACT ON KANSAS/MISSOURI/IOWA BEFORE SHIFTING NEAR THE GREAT LAKES. LOOKING AT THE SURFACE...MAIN PLAYER FOR OUR AREA WILL LIE WITH THE AREA OF HIGH PRESSURE CURRENTLY BUILDING IN BEHIND THE FRONT. CENTER OF HIGH EXPECTED TO LIE ACROSS THE DAKOTAS TODAY...BEFORE GRADUALLY SHIFTING EAST TONIGHT AND INTO THURSDAY. LIGHT NORTHERLY/EASTERLY WINDS EXPECTED...WITH CONTINUED BELOW NORMAL HIGH TEMPERATURES. AFTERNOON HIGHS FOR TODAY EXPECTED TO BE NEAR 70 DEGREES...WITH THURSDAY JUST A TOUCH WARMER AS THAT SURFACE HIGH SHIFTS EAST...REACHING INTO THE LOWER/MID 70S. OVERALL...VERY PLEASANT COUPLE OF DAYS EXPECTED. NEXT CHANGE ACROSS THE CWA EXPECTED TO ARRIVE LATE THURSDAY NIGHT/EARLY FRIDAY MORNING WITH A CHANCE FOR PRECIPITATION. UPPER LEVEL PATTERN SETS UP SO THAT A GOOD PORTION OF THE CONUS LIES UNDER THE INFLUENCE OF A BROAD TROUGH...WITH THE AXIS LYING THROUGH THE PLAINS. A SMALLER DISTURBANCE PASSING THROUGH THE FLOW WORKS ITS WAY EAST...AND LOOKS TO CROSS OVER THE CWA. ALONG WITH THE DISTURBANCE...A WEAK SURFACE FRONT PUSHES SOUTH INTO THE CWA...WHICH ALSO SITS IN A FAVORABLE POSITION FOR HELP FROM AN UPPER LEVEL JET STREAK MOVING OVERHEAD. DID INCREASE POPS ACROSS THE CWA...WITH BEST CHANCES COMING DURING THE DAYTIME HOURS ON FRIDAY. ALSO ADJUSTED TEMPS FOR FRIDAY DOWN A FEW DEGREES WITH THE CHANCES FOR PRECIP AND PLENTY OF CLOUD COVER AROUND...AND AM EXPECTING HIGHS TO STRUGGLE TO HIT 70. AS FAR AS THUNDERSTORM CHANCES...INSTABILITY NOT OVERLY IMPRESSIVE AT ANY LEVEL ACROSS THE CWA...BUT SOUTHERN AREAS ARE A BIT BETTER...SO TRENDED THE NORTHERN CWA DOWN TO JUST AN ISOLATED THUNDER MENTION. PRECIPITATION CHANCES LOOK TO LINGER ON THOUGH THE WEEKEND AND INTO EARLY NEXT WEEK...AS ADDITIONAL SHORTWAVE DISTURBANCES WORK INTO THE REGION. NO ADJUSTMENTS CHANGES TO POPS...AS MODELS STILL DIFFER WITH TIMING OF THESE DISTURBANCES AND ASSOCIATED PRECIP. WITH NO SIGNIFICANT CHANGES TO THE OVERALL PATTERN...LITTLE CHANGES EXPECTED IN REGARD TO TEMPERATURES...WITH BELOW NORMAL HIGHS STAYING IN THE 70S. && .AVIATION...06Z KGRI TAF. VFR CONDITIONS THROUGHOUT THE TAF. WIND MAY PICK UP A BIT FROM THE EAST FOR A PERIOD DURING THE DAY WEDNESDAY. SOME SCATTERED MID-LEVEL SKY COVER POSSIBLE TOWARD THE VERY END OF THE FORECAST...BUT NO CHANGE IN CATEGORY EXPECTED. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 320 AM CDT WED SEP 3 2008 .DISCUSSION... MAIN FORECAST CHALLENGE WILL BE CLOUD COVER AND PCPN CHANCES ASSOCIATED WITH GUSTAV REMNANTS TO OUR SOUTH. LATEST SATELLITE PICS AND RUC 500MB ANALYSIS SHOW REMNANTS OF GUSTAV SPINNING ACROSS ERN OK/WRN ARKANSAS WITH LARGE BLOCKING HIGH PRESSURE RIDGE ACROSS THE ERN CONUS. UPSTREAM...SHORTWAVE TROF AXIS EXTENDS ACROSS IDAHO AND INTO NEVADA. AT THE SFC...CHILLY HIGH PRESSURE HAS MOVED OVER THE NRN PLAINS AND INTO NORTH CENTRAL NEB. TEMPERATURES HAVE DROPPED INTO THE LOWER TO MID 40S UNDER THIS HIGH AND NOT A HUGE RECOVERY EXPECTED TODAY. CLEARING LINE BETWEEN GUSTAV TO THE SOUTH AND STRONG SUBSIDENCE TO THE NORTH WILL CONTINUE TO BISECT THE CWA TODAY. SOME SHOWERS ARE POSSIBLE ACROSS FAR SOUTHEAST NEBRASKA AND SOUTHWEST IOWA AS NORTHERN BANDS OF GUSTAV ROTATE THRU. BEST DIV Q TAKES PLACE FAR TO OUR SOUTH AND EAST BUT A FEW STRAY SHOWERS ARE POSSIBLE. THIS ACTIVITY WL LIKELY CONTINUE INTO THURSDAY AS THE SYSTEM MAKES ONLY LITTLE NEWD PROGRESSION WITH THE BLOCKING RIDGE TO THE EAST. TROF OVER THE WESTERN CONUS WL BROADEN AND SHIFT EAST THROUGH THE WEEK AND HELP TO MOVE GUSTAV REMNANTS TO OUR NORTHEAST. A SERIES OF WAVES WL MOVE THRU THE BROAD TROF AND INTO THE CNTRL PLAINS THRU THE WEEKEND. WL CONTINUE SMALL POPS FROM PREVIOUS FORECAST WITH NO MAJOR WARM UP ANTICIPATED. && .AVIATION... FOR TAF SITES KOMA/KLNK/KOFK. VALID THRU 04/06Z. KOFK IS UNDER THE INFLUENCE OF CLEAR SKIES...WHILE KLNK AND KOMA ARE UNDER THE INFLUENCE OF A MID CLOUD SCENARIO. VFR CONDITIONS ARE EXPECTED THROUGHOUT THE FORECAST PERIOD. BOTH KLNK AND KOMA ARE EXPECTED TO SCATTER OUT THROUGH THE MORNING HOURS BUT ONCE AGAIN...FALLING UNDER A MID CLOUD DECK SCENARIO...COMMENCING THIS AFTERNOON AND REMAINING AS SUCH THROUGHOUT THE FORECAST PERIOD. THE MID CLOUD DECK IS DUE TO THE PRESENT TRACK OF GUSTAV...WHICH SHOULD KEEP BAND OF PRECIPITATION WELL TO THE SOUTH AND EAST OF ALL TAF SITES. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ GRIFFIS/REESE ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 948 PM CDT THU SEP 4 2008 .UPDATE... UPPER LOW MOVING THRU NE ND THIS EVENING WITH WIDESPREAD RAIN AREA OVER NE ND/NW MN AND SRN MANITOBA. AREA OF RAIN SPREADING SLOWLY EAST AND COORD WITH WFO DLH TO UP POPS TO CATEGORICAL OVER NW MN NORTH OF HIGHWAY TWO. OTHERWISE...RAIN SHOWERS WILL DECREASE IN COVERAGE OVER NE ND OVERNIGHT. SE ND/WCNTRL MN WILL BE ON THE SRN EDGE OF ANY SHOWERS WITH MAJORITY OF ANY SHOWERS STAYING NORTH OF A JMS-FAR-DTL-PKD LINE THRU 12Z. WITH CLOUD COVER IN PLACE FORSEE LITTLE TEMP FALL OVERNIGHT WITH ALL SITES 46-50 DEGREES FOR LOWS. THIS DID REQUIRE RAISING LOWS IN DVL BASIN AS PREV FCST OF AROUND 40-42 SEEMED TOO LOW BASED ON EXPECTED CLOUD COVER OVERNIGHT. && .AVIATION... MAIN FCST CONCERN IS WILL LOWER CLOUDS FORM/MOVE IN LATER TONIGHT ON BACKSIDE OF UPPER LOW. RUC HINTS AT THE MVFR DECK THAT WAS OVER MINOT-ESTEVAN AREA TODAY RE-DEVELOPING OVER NE ND AFTER 09Z SO INCLUDED THIS IN THE TAF. ALSO DID THIS AS WELL FOR NW MN CLOSER TO 12Z. && .PREV DISCUSSION... /ISSUED 325 PM CDT THU SEP 4 2008/ SHORT TERM... MAIN FORECAST CHALLENGE IS PRECIPITATION. WHEN LOOKING AT THE LATEST SURFACE ANALYSIS...AN AREA OF LOW PRESSURE EXTENDS THROUGH W ND INTO CENTRAL SD. KMVX SHOWS AN AREA OF SHRA MAINLY IN NE ND NEAR DVL WITH ISOLD SHRA ELSEWHERE. WHEN COMPARING THE MODELS...THE MODELS ARE ACTUALLY IN PRETTY GOOD AGREEMENT AS FAR AS SYSTEM TIMING...SO ENDED UP LEANING TOWARD THE GFS AS THE COMPROMISE MODEL SOLUTION FOR THE FORECAST. THE LOW DRIFTS SLOWLY SE TONIGHT AND FRI. THUS...EXPECT PCPN TO DRIFT SE AS WELL. LIMITED INSOLATION TODAY HAS KEPT INSTABILITY DOWN AND HAVE ONLY SEEN A COUPLE OF LTG STRIKES IN NW MN THIS AFTERNOON...WHERE THEY DID SEE MORE SUNSHINE EARLIER. ANY THREAT FOR TSRA IS EXPECTED TO QUICKLY DIMINISH AS PEAK HEATING PASSES. CONSEQUENTLY...KEPT JUST SHRA IN THE FORECAST FOR TONIGHT. ON FRI...THE LOW MOVES INTO MN AND WEAKENS...WITH NW FLOW EXPECTED OVER THE MAJORITY OF THE AREA. CLOUD COVER WILL ONCE AGAIN BE THE PRIMARY FACTOR IN DETERMINING IF THERE WILL BE ENOUGH INSOLATION TO PRODUCE ISOLD TSRA ON FRI AFTERNOON OR NOT. MODELS DO INDICATE SOME WEAK INSTABILITY...SO WILL LEAVE MENTION IN FORECAST FOR NOW. A WEAK HIGH PRESSURE RIDGE QUICKLY MOVES THROUGH THE AREA ON FRI NIGHT AHEAD OF ANOTHER LOW THAT IS EXPECTED TO CROSS ND ON SAT...BRINGING THE NEXT CHANCE FOR PCPN TO THE AREA BY SAT AFTERNOON. WITH THE 500MB TROF ANTICIPATED TO MOVE ACROSS THE AREA IN CONJUNCTION WITH THE SURFACE LOW...APPEARS AT THIS TIME THAT NE ND AND NW MN WILL BE IN THE BEST LOCATIONS TO RECEIVE ADDITIONAL RAINFALL THROUGH SUN. LONG TERM [MON-THU]... BROAD TROUGH OVER THE NATIONS MIDSECTION LOOKS TO BE E OF THE FA BY MON MORNING. COULD BE SOME WEAK RIDGING IN ITS WAKE WITH ANOTHER TROUGH SET TO DROP DOWN BY THU. WILL KEEP A DRY FORECAST FOR MON AND TUE...THEN A FRONT LOOKS TO MOVE THRU SOMETIME FROM WED INTO THU. WILL KEEP SOME CHANCES FOR PCPN DURING THIS TIME FRAME. NOT VERY GOOD AGREEMENT BETWEEN THE GFS AND ECMWF...AND THE NATIONAL DISCUSSIONS ARE FAVORING THE ECMWF TODAY. TEMPS STILL LOOK TO STAY ON THE COOL SIDE. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ RIDDLE/NG nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 228 PM EDT WED SEP 3 2008 .SYNOPSIS... A WEAKENING AND FAIRLY DRY COLD FRONT WILL DROP SOUTHEAST THROUGH THE GREAT LAKES TODAY. THIS FRONT WILL DISSIPATE OVER SOUTHERN OHIO AND THEN MOVE NORTH AS A WARM FRONT ON THURSDAY. THIS WARM FRONT IS ASSOCIATED WITH A SURFACE LOW FROM THE REMNANTS OF GUSTAV...MOVING NORTH THROUGH THE MIDWEST AND WESTERN OHIO VALLEY. && .NEAR TERM /THROUGH TONIGHT/... LATEST RUC MODEL INDICATED INCREASED CAPE OVER WEST THIS AFTERNOON AND WITH WEAK FRONT SAGGING INTO AREA FROM THE NW TODAY WOULDN`T BE SURPRISED TO SEE ISOLATED LATE AFTERNOON AND EVENING SHOWERS OR THUNDERSTORMS IN THE WEST. ADDED SLIGHT CHANCE TO WESTERN ZONES AFTER 18Z. ONE FACTOR WORKING AGAINST DEVELOPMENT OF CONVECTION WOULD BE A BIT DRIER AIR TODAY AS COMPARED TO YESTERDAY. HIGHS THIS AFTERNOON OF AROUND 90 TO THE LOWER 90S SEEMS TO BE ON TRACK. OVERNIGHT LOWS WILL DROP TO THE DEWPOINTS IN THE LOW AND MID 60S. REMAINDER OF THE FORECAST LOOKS GOOD AND NO OTHER CHANGES WERE MADE. && .SHORT TERM /THURSDAY THROUGH SATURDAY/... COLD FRONT WORKS IN THIS EVENING AND STALLS N OF THE OHIO RIVER...WORKING NWD AS A WARM FRONT ON THURSDAY. REMNANTS OF GUSTAV ARE PROGGED TO TRACK SSW-NNE OVER INDIANA ON FRIDAY WITH THE SFC LOW. A BAND OF MOISTURE ALONG THE TRAILING FRONT WILL SLOWLY PRESS EAST ON FRIDAY NIGHT AND SATURDAY...INTO OHIO. THIS MAY REMAIN FURTHER WEST OVER INDIANA IF HANNA KEEPS A MORE WESTERLY TRACK...BUT LATEST RUNS ARE A BIT FURTHER EAST WHICH WOULD MAKE THE LEFTOVER GUSTAV REMNANTS MORE PROGRESSIVE INTO OHIO. SERN FCST AREA MAY NOT SEE ANY PRECIPITATION AS IT IS TRAPPED BETWEEN TWO SYSTEMS. TEMPS ON THURS AND FRI SHOULD BE WARMEST IN THE SE WHERE DRIER AIR AND LESS CLOUD COVER SHOULD ALLOW FOR A BIT STRONGER HEATING. && .LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/... DID NOT FAVOR ANY BIG CHANGES TO THE FORECAST AFTER SATURDAY NIGHT AS THE PATH OF TROPICAL SYSTEMS WILL BE BETTER RESOLVED WITH LATER FORECASTS. MODELS ARE SHOWING THAT ANY LEFTOVERS WILL MOVE EAST WITH HANNA AND DRY OUT OHIO VALLEY SATURDAY NIGHT. COOLER AIR WITH CLOUD COVER AND INCREASED POTENTIAL FOR RAIN IS BEING PROGGED FOR THE LATTER PARTS OF THE FORECAST. THIS IS AS A COLD FRONT STRETCHES THROUGH THE EASTERN HALF OF THE CONUS MONDAY AND MORESO ON TUESDAY. ADDED A CHANCE OF RAIN ON TUESDAY WHICH WAS PREVIOUSLY DRY. PREV DISCUSSION BELOW... EXTENDED PERIOD WILL BE HIGHLIGHTED BY REGION GETTING PASSED TO THE WEST AND EAST BY GUSTAV AND HANNA RESPECTIVELY...THEN A POTENTIAL PATTERN CHANGE ERLY NEXT WEEK AS COOLER AIRMASS INVADES OH VLY/GRT LKS. MODEL GUIDANCE CONTINUES TO REMAIN IN GOOD AGREEMENT WRT REMNANTS OF GUSTAV AND HANNA AND IMPACTS TO THE REGION. OH VLY WILL REMAIN UNDERNEATH AN ELONGATED UPR RIDGE WITH ORIGINS IN THE WRN ATLC OCEAN AS HANNA APPCHS SE CONUS AND REMNANTS OF GUSTAV LINK UP WITH A FRNTL BNDRY TO NORTH/WEST OF REGION. THE PLACEMENT OF THE RIDGE IS PROBLEMATIC FOR ALLOWING DEEPEST TROPICAL MOISTURE ASSOCD WITH GUSTAV TO WORK INTO FCST AREA...AS REMNANT LOW IS ESSENTIALLY FORCED NORTHEAST INTO THE CNTRL GRT LKS AND AROUND THE RIDGE. COMPLICATING MATTERS IS EVENTUAL TRACK OF HANNA WHICH SHOULD LIFT NORTH INTO THE CAROLINAS AROUND THE WEST SIDE OF THE RIDGE FRI...THEN GET PICKED UP BY UPR TROF ACRS CNTRL CONUS IN WAKE OF AFOREMENTIONED FRNTL BNDRY. WHILE THERE REMAINS PLENTY OF UNCERTAINTY...THE INTERACTION OF ALL OF THESE DIFFERENT FEATURES MENTIONED ABV ARE WORKING AGAINST RAINFALL POTENTIAL ACRS MUCH IF NOT ALL OF THE FCST AREA. WHILE CHANCES FOR RAIN ARE POSSIBLE AS REMNANTS OF GUSTAV PASS NORTHWEST OF FCST AREA ON FRI...BELIEVE STRENGTH OF THE UPR RIDGE WILL ESSENTIALLY HOLD FRNTL BNDRY IN PLACE TO WEST AND FORCE WHAT IS LEFT OF GUSTAV INTO THE CNTRL GRT LKS. MEANWHILE...MODELS TIGHTLY CLUSTERED ON TRACK OF HANNA THRU THE CAROLINAS N/NE INTO THE APPALACHIANS AND NEW ENGLAND BY SUN MRNG. WHILE THE WESTERN PERIPHERY OF THE STEADIER RAIN ASSOCD WITH HANNA MAY GRAZE EASTERN COUNTIES FRI NIGHT AND SAT...THE SUBSIDENCE SURROUNDING THE WEAKENING TROPICAL SYSTEM WILL LIKELY KEEP MAJORITY OF THE FCST AREA DRY AS IT PASSES TO THE EAST OF THE REGION. TO SUM IT UP...IT APPEARS MORE LIKELY THAT THE FCST AREA IS SIMPLY GOING TO BE IN THE WRONG LOCATION TO TAP INTO ANY OF THE COPIOUS MOISTURE ASSOCD WITH EITHER GUSTAV OR HANNA. A SHAME TOO CONSIDERING AREA COULD REALLY USE SOME BENEFICIAL RAINS. WITH STILL SOME UNCERTAINTY...WILL MAINTAIN 20 POPS FOR MUCH OF THE FCST AREA FRI INTO SAT. HAVE PLACED SLIGHTLY HIGHER POPS OVER FAR ERN COUNTIES FRI NIGHT/SAT AS HANNA PASSES BY. AFOREMENTIONED FRNTL BNDRY WILL FINALLY SWING THRU FCST AREA SAT NIGHT/ERLY SUN ONCE HANNA MOVES OFF TO THE NORTHEAST. HOWEVER... WITH THE TROPICAL SYSTEMS TAKING ALL OF THE MOISTURE...BNDRY MAY COME THRU DRY. FROPA WILL USHER IN A COOLER AIRMASS AND TAKE EDGE OFF THE HEAT...WITH TEMPS CLOSER TO MORE SEASONABLE LEVELS. A STRONGER COLD FRONT WILL MOVE THRU THE OH VLY MON AFTN/NIGHT...WITH A MUCH COOLER AIRMASS SPREADING ACRS THE REGION IN ITS WAKE FOR TUES. THIS FRONT WILL NOT HAVE GULF MOISTURE FEED TO TAP INTO...SO WILL ONLY INDICATE LO CHC POPS ATTM. HIGHS WILL BE IN THE M/U80S ON FRI AND DEPENDING ON EXTENT OF CLOUDS...SOME LOCATIONS ACRS THE SOUTH COULD MAKE A RUN AT 90 DEG. HIGHS WILL FALL BACK INTO THE U70S/L80S BY MON...WITH PLEASANT AFTN HIGHS ON TUES IN THE 70S IN WAKE OF FROPA. LOWS GENERALLY IN THE 60S WILL SCALE BACK INTO THE 50S BY MIDWEEK NEXT WEEK. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... NAM REMAINS MORE UNSTABLE THAN THE GFS WITH ATMOSPHERE. RIGHT NOW WILL LEAN TOWARDS THE GFS AND WONT MENTION ANY TS OR CB...ESPECIALLY AT KDAY. ISOLD CONVECTION WILL BE POSSIBLE AFTER 20Z BUT EXPECT TO SEE ACTIVITY MAINLY NORTH AND WEST OF TAF SITES. MIGHT SEE SOME BKN AC IN KDAY AS H7 MOISTURE INCREASES. LIFT AHEAD FNT WEAKENS A LITTLE AROUND 00Z AS FOCUS SHIFT FAR W NR LOW CENTER AS IT LIFT N. STILL MIGHT BE A FEW HIGH CU/LOW AC ACRS THE N OVER THE COURSE OF THE NIGHT. BKN CI SHOULD OVERRUN THE TAFS AFT 00Z AHEAD OF LOW. OUTLOOK...TSTM POSSIBLE FRIDAY INTO SATURDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...PARKER NEAR TERM...PARKER SHORT TERM...FRANKS LONG TERM...FRANKS/RYAN AVIATION...PARKER oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 1157 AM EDT THU SEP 4 2008 .SYNOPSIS... HIGH PRESSURE WILL KEEP FAIR WEATHER OVER THE REGION THROUGH AT LEAST THE FIRST PART OF FRIDAY BEFORE TROPICAL STORM HANNA BEGINS TO AFFECT THE LOCAL AREA WEATHER. A RETURN TO DRY CONDITIONS IS EXPECTED SUNDAY INTO MONDAY...AS HIGH PRESSURE BUILDS EASTWARD. A COLD FRONT FROM THE PLAINS WILL BRING A CHANCE OF SHOWERS AND THUNDERSTORMS TO THE AREA ON TUESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... NOT A LOT GOING ON TODAY...JUST A SOME HIGH CLOUDS SPILLING OVER THE UPPER RIDGE INTO PA....MAKING FOR A MOSTLY SUNNY TO SUNNY DAY ACROSS CENTRAL PA. ALSO ANOTHER HOT DAY IN STORE AS 850 TEMPS 18-20C...1-2 STD DEV ABOVE NORMAL...SUPPORTING 80S TO LOWER 90S EVERYWHERE. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... FRIDAY WILL AT LEAST START OFF FAIR AS THE LAST OF THE NOSE OF HIGH PRESSURE HANGS TOUGH OVER THE STATE. BETWEEN A WEAK FRONT APPROACHING FROM THE WEST AND POTENTIAL MOISTURE APPROACHING FROM HANNA OVER THE SE...DID SNEAK IN SOME VERY SMALL CHC POPS OVER THE NW AND SE BY DAY`S END. CONFIDENCE IS ACTUALLY PRETTY HIGH HOWEVER THAT MOST OF THE AREA WILL REMAIN DRY FOR MOST OF THE DAY. IT WILL REMAIN WARMER THAN NORMAL FOR PROBABLY THE LAST DAY IN OUR RECENT STRING. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... ALL EYES TURN TO HANNA AFTER FRIDAY. AS OF 07Z...SATELLITE SHOTS DON`T EXACTLY DEPICT A FEROCIOUS LOOKING STORM. THE CONVECTION IS ALL BUT ABSENT AND THE STRUCTURE IS VERY ASYMMETRICAL...STRETCHED VERY EAST TO WEST. OBSERVATIONS FROM THE VICINITY DO SHOW SOME 30KT SUSTAINED WINDS AND THE DISTANCE FROM THE STORM INDICATES ITS A VERY LARGE CIRCULATION. THIS SUGGESTS THAT INTENSITY CHANGES WILL TEND TO BE SLOW. MODELS ARE PRETTY CONSISTENT IN TAKING THE STORM UP OR JUST INLAND ALONG THE EASTERN SEABOARD AFTER A LANDFALL IN THE CAROLINAS LATE FRIDAY NIGHT OR EARLY SAT MORNING. AS IS USUALLY THE CASE WITH REMNANT TROPICAL CYCLONES IN PA...DON`T THINK THE WIND WILL BE THE REAL ISSUE...RATHER THE POTENTIAL FOR HEAVY RAIN. THE ECMWF/GFS AND NAM ALL POINT TO THE BEST POTENTIAL FOR HEAVY RAIN OVER MY SERN ZONES. COARSER MODEL ENSEMBLE PLUMES PREDICTABLY SHOW MORE MODEST VALUES...AVERAGING OUT THE EXTREME SOLUTIONS. SREFS SHOW ON AVERAGE AROUND A HALF INCH OF RAIN IN THE CENTRAL MOUNTAINS TO AROUND 1.50" OVER MY FAR SERN ZONES. THE GEFS PLUMES SHOW EVEN A TIGHTER GRADIENT WITH UNDER .25" LOCALLY TO AROUND 1" OVER THE SE. OPERATIONAL MODELS ALL SHOW 2 INCHES OR MORE FROM HARRISBURG SOUTH AND EAST. USING SOME SLIGHTLY TWEAKED HPC NUMBERS I CAME UP WITH AMOUNTS RANGING FROM NEAR 2" IN THE SE TO ABOUT .25 LOCALLY...WITH ANOTHER .30 OR SO POSSIBLE OVER THE NW CLOSEST TO AN APPROACHING FRONT. SMALL CHANGES IN HANNA`S EVENTUAL TRACK AND INTENSITY COULD RESULT IN PRETTY BIG VARIATIONS IN MY CURRENT FORECAST. IT`S STILL QUITE EARLY IN THE GAME GIVEN THE STORM`S LACK OF ORGANIZATION AND DISTANCE FROM LANDFALL. AFTER HANNA...HIGH PRESSURE PROMISES RELATIVE TRANQUILITY INTO AT LEAST TUESDAY BEFORE ANOTHER FRONT BRINGS A CHANCE OF SHOWERS. TEMPS WILL RETURN CLOSER TO SEASONAL NORMS AS WE LOSE THE BIG UPPER RIDGE AND IT GETS REPLACED BY SOME WEAK TROFFING. && .AVIATION /16Z THURSDAY THROUGH MONDAY/... PATCHY SHALLOW FOG REDUCING VSBYS TO MVFR IN MANY LOCATIONS AS OF 11Z. RUC13 DATA SUGGESTS THIS FOG WILL BURN OFF BY ARND 13Z. A DYING COLD FRONT OVR LK ERIE ATTM IS FCST TO BECOME NEARLY STATIONARY ALONG THE PA/NY BORDER LATER TDY. LIMITED MSTR AND WEAK FORCING INVOF OF THE FNTL BNDRY SUGGESTS A VERY LOW PROB OF PCPN /10% OR LESS/ IN THIS AREA DURING THE AFTN. VFR FLYING CONTINUES TERMINAL/WIDE WITH JUST A FEW FAIR WX CU. MUCH...IF NOT ALL...OF FRIDAY LOOKS DRY AS HIGH PRES REMAINS WEDGED OVER THE REGION IN BTWN NWD MOVG GRT LKS LOW /REMNANTS OF GUSTAV/ AND APPROACHING HANNA FM THE SERN MID ATLC. THE HIGH SHOULD EVENTUALLY BE OVERCOME BY DEEPER MSTR ASSOC WITH HANNA FRI NGT THRU SAT...WHICH IS FCST TO EVENTUALLY SLIDE NEWD ALONG THE ERN SEABOARD. LOOK FOR THE BEST CHC FOR RNFL AND ASSOC ADVERSE FLYING CONDS LATE FRI NITE AND SAT...ESP OVER ERN SECTIONS. HIGH PRESSURE BUILDS IN TO CLOSE OUT THE WEEKEND AND INTO EARLY NEXT WEEK WITH VFR CONDS RETURNING TO THE REGION. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LACORTE NEAR TERM...LACORTE/GARTNER SHORT TERM...LACORTE LONG TERM...LACORTE AVIATION...FITZGERALD pa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MEMPHIS TN 958 PM CDT WED SEP 3 2008 .UPDATE... WILL UPDATE TO ADD HEAVY RAINFALL MENTION LINE ALONG AND WEST OF A WALNUT RIDGE AR TO MEMPHIS TO COFFEEVILLE MS LINE TONIGHT. WILL ADJUST OTHER ELEMENTS...MAINLY TO INCREASE OVERNIGHT LOWS. && .DISCUSSION... APPEARS THE TORNADO THREAT IS DECREASING IN AND NEAR THE TORNADO WATCH AREA...WHILE HEAVY RAIN AND LOCALIZED FLOODING THREATS ARE INCREASING. AT 945 PM CDT ACROSS THE MIDSOUTH AND FORECAST AREA...RAIN WAS OCCURRING WEST OF A PARAGOULD AR TO HOUSTON MS LINE. A TORNADO WATCH WAS IN EFFECT FOR AREAS ALONG AND SOUTH OF A MARIANNA AR TO COLDWATER MS TO CALHOUN CITY MS LINE. TROPICAL DEPRESSION GUSTAV WAS OVER SW AR SLOWLY MOVING NE. FIRST...APPEARS THE TORNADO POTENTIAL IS LIMITED FOR THE REST OF TONIGHT WITH WIDESPREAD RAIN STABILIZING THE AIR IN AND NEAR THE WATCH AREA. THE WATCH MAY BE CANCELLED EARLY. THE LACK OF INSTABILITY APPEARS TO BE THE MAIN BARRIER TO DEVELOPMENT AS SHEAR IS ABUNDANT. SUPPOSED IF MORE UNSTABLE AIR OVER CENTRAL MS WITH SURFACE TEMPERATURES AROUND 78/79 AND 73/74 DEWPOINTS COULD GET INTO NORTH MS...CHANCES FOR TORNADOES WOULD INCREASE...BUT THIS IS UNLIKELY. THINK ADDITIONAL TORNADO WATCHES ARE UNLIKELY. SECOND...HEAVY RAIN AND LOCALIZED FLOODING MAY BE THE BIGGER CONCERN FOR THE REST OF TONIGHT ROUGHLY ABOUT 30 MILES EAST AND WEST OF A WEST MEMPHIS AR TO CHARLESTON MS LINE...INCLUDING MEMPHIS... TUNICA...AND BATESVILLE. LATEST RUC/NAM MODELS IN GOOD AGREEMENT OF A VERY STRONG LOW LEVEL MOISTURE CONVERGENCE AREA DEVELOPING IN THESE AREAS...BASICALLY THE NARROW LINE OF HEAVY RAIN OVER CENTRAL MS SLOWLY ADVANCING NORTHEAST. GREENVILLE MS HAS RECORDED OVER 5 INCHES OF RAINFALL SINCE 6 PM CDT. THIS BAND OF HEAVY RAIN WILL LIKELY AFFECT THE AREAS MENTIONED ABOVE AND MAY PRODUCE 2 TO 4 INCHES IN A FEW AREAS. FLASH FLOOD WARNINGS MAY BE NEEDED. THE LOW WITH GUSTAV WILL CONTINUE TO MOVE NORTHEAST TONIGHT... REACHING NE AR BY THURSDAY MORNING. A MID LEVEL DRY SLOT WILL NARROW THE AREA OF RAIN LATER TONIGHT TO THE LOW LEVEL CONVERGENCE BOUNDARY. MAY HAVE TO CONTEND WITH A FEW STRONG TO SEVERE STORMS WITH DAMAGING WINDS AND POSSIBLE TORNADOES ON THURSDAY NEAR THE CONVERGENCE BOUNDARY...MAINLY EAST OF THE MS RIVER. UPDATE WILL BE OUT SHORTLY. && .PREV DISCUSSION... /ISSUED 702 PM CDT WED SEP 3 2008/ UPDATE... UPDATED FORECAST AND HWO TO INCLUDE NEW TORNADO WATCH SOUTH OF A FORREST CITY AR TO COLDWATER MS TO CALHOUN CITY MS LINE AS WELL AS ADD HEAVY RAINFALL AND LOCALIZED FLOODING NEAR THESE AREAS. DISCUSSION... TORNADO AND HEAVY RAINFALL POTENTIAL TONIGHT ARE THE MAIN CONCERNS. NEW TORNADO WATCH INCORPORATES THE LOCATIONS MENTIONED ABOVE UNTIL 2 AM CDT. WILL MONITOR FOR BRIEF SPINUPS ALONG A BAND OF SHOWERS AND FEW THUNDERSTORMS ROTATING NORTHEAST ON THE EAST SIDE OF TROPICAL DEPRESSION GUSTAV. WIND/SHEAR PARAMETERS ARE IMPRESSIVE WITH 0-1 KM SR HELICITY 350-550 M2/S2 IN THE BAND...BUT INSTABILITY IS NOT IMPRESSIVE WITH MLCAPES GENERALLY BELOW 300 J/KG. WITH THE LACK OF INSTABILITY...NOT CONFIDENT THAT TORNADOES WILL OCCUR IN THE FORECAST AREA. THE BEST INSTABILITY SHOULD MAINLY STAY SOUTH OF THE AREA. DEFINITELY NOT EXPECTING AN OUTBREAK AND SIGNIFICANT TORNADOES...EF2 OR GREATER...REMAIN VERY UNLIKELY. THE BAND WILL PUSH NORTHEAST THROUGH THE NIGHT AND EVENTUALLY INTO THE MEMPHIS AND JONESBORO AREAS. CANNOT COMPLETELY RULE OUT ADDITIONAL TORNADO WATCHES FOR THESE AREAS...ESPECIALLY IF TORNADO TOUCHDOWNS AND DAMAGE OCCURS OVER THE NEXT HOUR OR TWO. AT THIS TIME...THINK THE TORNADO POTENTIAL WILL LESSEN THROUGH THE NIGHT WITH THE LOSS OF DAYTIME HEATING...THUS THINK CHANCES FOR ADDITIONAL WATCHES REMAIN LOW. HEAVY RAIN IN THE BAND WILL BE A CONCERN TONIGHT...PRIMARILY WEST OF A JONESBORO AR TO COFFEEVILLE MS LINE...WHERE 1 TO 3 INCHES AND LOCALIZED FLOODING MAY OCCUR. A STRONG LOW LEVEL JET...850 MB 45 KTS AND GREATER...WILL FOCUS MOISTURE CONVERGENCE ALONG THE BAND AND BRING HEAVY RAINFALL RATE OF 1 INCH OR GREATER PER HOUR. AS THE BAND SHIFTS EAST...THE HEAVY RAIN WILL SHIFT EAST THROUGH THE NIGHT. WILL KEEP UPDATING THROUGHOUT THE NIGHT. PREV DISCUSSION... /ISSUED 314 PM CDT WED SEP 3 2008/ DISCUSSION... PRIMARY FORECAST CONCERN REMAINS RAIN ASSOCIATED WITH THE REMNANTS OF TROPICAL SYSTEM GUSTAV. WITH LIMITED INSTABILITY...RAIN AMOUNTS HAVE NOT BEEN SUFFICIENT FOR FLASH FLOODING OVER THE MIDSOUTH... BUT A GENERAL SOAKING RAIN. AT DISCUSSION TIME...THE LOW LEVEL CENTER OF WHAT WAS GUSTAV WAS CENTERED OVER SOUTHWEST AR. THIS CIRCULATION WAS BECOMING INCREASINGLY EVIDENT ON LONG RANGE KNQA RADAR REFLECTIVITY. THE MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT IN LIFTING THE REMNANTS OF GUSTAV TO THE CHICAGO AREA BY THURSDAY EVENING. A TRAILING SURFACE FRONT WILL GRADUALLY LIFT EAST THROUGH THE MIDSOUTH THURSDAY. FORCING ALONG THIS FRONT WILL BE WEAK...AS WILL BE UPPER SUPPORT BEHIND THE DEPARTING MID LEVEL LOW. LOW LEVEL INSTABILITY IS PROGGED BY THE NAM TO REACH AS HIGH AS 800 J/KG...IN A NARROW AXIS EAST OF THE MS RIVER DURING THE AFTERNOON. THIS IS REASONABLE...ASSUMING SUFFICIENT SURFACE HEATING. WILL CONTINUE WITH HIGH CHANCE TO LIKELY POPS ON THURSDAY. MAY HAVE TO TRIM THURSDAY POPS FURTHER...ESPECIALLY IF THE DRY AIR OVER THE SOUTHERN AND CENTRAL PLAINS FILTERS IN FASTER THAN EXPECTED...OR IF BREAKS IN THE CLOUDS FAIL TO APPEAR. BOTH GFS AND ECMWF DEVELOP AN UPPER LEVEL LONGWAVE TROF OVER THE MIDWEST THIS WEEKEND. BESIDES ALLOWING A DRY CONTINENTAL SURFACE HIGH PRESSURE INTO THE MIDSOUTH...THIS UPPER LEVEL LONGWAVE TROF WILL LIKELY PLAY A ROLE IN THE TRACK OF TROPICAL SYSTEM IKE. TO WHAT EXTENT...IT/S A BIT TOO EARLY TO TELL. THE GFS ECMWF CONTINUE TO BRING IKE UP THE EASTERN SEABOARD...CURING IT NORTH JUST AS IT APPROACHES MIAMI. ECMWF CURIOUSLY APPEARS TO LIFT THE LONGWAVE TROF OUT...FLATTENING THE FLOW...BEFORE TURNING IKE. NOT COMPLETELY CONFIDENT IN THIS SCENARIO. PLEASE REFER TO LATEST FORECASTS AND ADVISORIES FROM THE NATIONAL HURRICANE CENTER. IKE/S ULTIMATE PATH NOTWITHSTANDING...IT APPEARS DRIER AND A LITTLE COOLER CONDITIONS ARE IN STORE THE MIDSOUTH THIS WEEKEND... INTO EARLY NEXT WEEK. && .PRELIMINARY POINT TEMPS/POPS... MEM 72 80 67 82 / 100 60 30 10 MKL 72 82 65 80 / 50 50 40 10 JBR 72 79 63 81 / 100 80 20 10 TUP 72 83 69 84 / 50 40 30 20 && .MEG WATCHES/WARNINGS/ADVISORIES... AR...NONE. MO...NONE. MS...NONE. TN...NONE. && $$ MBS/PWB tn AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE AMARILLO TX 1143 PM CDT TUE SEP 2 2008 .AVIATION... A BAND OF SHOWERS...WITH A FEW EMBEDDED THUNDERSTORMS...HAS DEVELOPED OVER THE CENTRAL PORTIONS OF THE TX/OK PANHANDLES THIS EVENING IN AREA OF H85-H7 FRONTOGENESIS. THESE SHOWERS ARE EXPECTED TO PERSIST THROUGH MUCH OF THE NIGHT...POTENTIALLY IMPACTING KAMA/KGUY. MENTION OF SHOWERS HAS BEEN INCLUDED ACCORDINGLY. CIGS ARE EXPECTED TO REMAIN ABOVE 3 KFT ACROSS THE NORTH...ALTHOUGH WE COULD SEE SOME TEMPO MVFR CIGS AT KGUY...WHILE MVFR CONDITIONS ARE EXPECTED FOR MUCH OF THE NIGHT AT KAMA. ANY LOW CIGS ARE EXPECTED TO LIFT BY 15Z ALTHOUGH THE NAM MODEL IS KEEPING THESE LOW CLOUDS IN INTO THE AFTERNOON HOURS AT KAMA. THIS WILL BE SOMETHING TO KEEP AN EYE ON. NORTH WINDS WILL INCREASE BY MID MORNING AS HIGH MOMENTUM AIR ALOFT MIXES DOWN TO THE SURFACE. THESE WINDS WILL BEGIN TO RELAX BY MID AFTERNOON AND SLOWLY VEER TO THE NORTHEAST. AFTER 01Z...WIND SPEEDS SHOULD DROP BELOW 10 KTS FROM A GENERAL EASTERLY DIRECTION. JOHNSON && .PREV DISCUSSION... /ISSUED 658 PM CDT TUE SEP 2 2008/ UPDATE... HAVE ISSUED UPDATE TO GRAPHICAL FCSTS...WITH UPDATE TO TEXT PRODUCTS TO BE ISSUED SHORTLY. HAVE REDUCED POPS TO ISOLATED FOR THE REST OF TNGT. HAVE ELIMINATED MENTION OF THUNDER. HAVE ELIMINATED MENTION OF HEAVY RAIN. HAVE LOWERED QPF AMOUNTS. MID AND UPPER LEVEL FLOW REMAIN WEAK...WITH FEW OPPORTUNITIES FOR DYNAMIC FORCING. LOW LEVEL CONVERGENCE ZONE IS WELL S OF FCST AREA...WITH LITTLE UPSLOPE COMPONENT OVER PNHDLS. MID LEVEL LAPSE RATES ARE NOT IMPRESSIVE...INSTBY IS WANING...AND CURRENT RADAR TRENDS INDICATE NO STRENGTHENING OF EXISTING WEAK SPARSE ECHOES. ISENTROPIC LIFT IS EXPECTED TO IMPROVE SLGTLY TNGT...ELSE WOULD PULL POPS ENTIRELY. NO OTHER CHANGES AT THIS TIME. COCKRELL PREV DISCUSSION... /ISSUED 619 PM CDT TUE SEP 2 2008/ AVIATION... A FEW SHOWERS LOCATED OVER THE NORTH CENTRAL TX PANHANDLE WILL CONTINUE TO WEAKEN THIS EVENING. THIS SHOULD RESULT IN A GENERALLY DRY FORECAST OVERNIGHT. NORTH WINDS IN THE WAKE OF THIS MORNING/S COLD FRONT WILL ALSO BEGIN TO SUBSIDE AROUND SUNSET...BUT SHOULD STAY IN THE 12 TO 15 KT RANGE THROUGHOUT THE NIGHT. THE TRICKY PART OF THIS FORECAST IS WHAT TO DO WITH LOW CIGS. THE DRIER AIR PRESENT ACROSS THE NORTHWEST PORTION OF THE CWA WILL BE A LIMITING FACTOR IN HOW EXPANSIVE ANY LOW CLOUDS ARE OVERNIGHT. THEREFORE...THE CURRENT FORECAST FOR KDHT IS VFR. I HAVE A BRIEF WINDOW LATER THIS EVENING OF MVFR CIGS AT KGUY...BUT VFR GENERALLY AFTER 05Z. FOR KAMA...I OPTED TO DEPICT PREVAILING MVFR CIGS FROM 03Z TO 15Z GIVEN THE AGREEMENT BETWEEN THE GFS/NAM/RUC BUFKIT SOUNDINGS. THERE COULD BE SOME TEMPORARY BREAKS GIVEN THE FACT THAT WINDS WILL NOT BE UPSLOPE BUT MORE FROM THE NORTH. IF THESE CIGS DO HOLD THROUGH THE NIGHT...THEY ARE EXPECTED TO LIFT BY MID MORNING...GIVING WAY TO VFR CONDITIONS THROUGH THE REMAINDER OF THE FORECAST. WINDS COULD BECOME GUSTY AGAIN BY 15Z WEDNESDAY MORNING BUT SHOULD RELAX BY MID AFTERNOON. JOHNSON PREV DISCUSSION... /ISSUED 408 PM CDT TUE SEP 2 2008/ DISCUSSION... COLD FRONT HAS PUSHED THROUGH THE PANHANDLES...BRINGING COOLER AND DRIER AIR WITHIN THE LOWER LEVELS. UP ABOVE THIS LAYER...MOIST AND UNSTABLE CONDITIONS PERSIST AND MAINTAIN AN ENVIRONMENT FAVORABLE OF SHOWERS AND THUNDERSTORMS. WATER VAPOR SATELLITE SHOWED A NARROW BAND OF MOISTURE...STREAMING FROM NORTHEAST MEXICO TO THE MIDWEST U.S. BY WAY OF THE PANHANDLES. AN UPPER LEVEL JET APPEARS TO BE LIFTING ACROSS THE SOUTHERN ROCKIES AND THE RIGHT REAR QUADRANT COULD TRACK OVER THE SOUTHERN PLAINS THIS EVENING. WE WILL KEEP THE POPS GOING THROUGH THE NIGHT...BUT WILL SHUT DOWN PRECIPITATION BY SUNRISE. GIVEN THE DEEP MOISTURE AND SLOW PACE OF STORMS...HEAVY RAINFALL IS STILL POSSIBLE. AN UPPER LEVEL TROUGH SLIDES OVER THE CENTRAL U.S. BEHIND THE EXITING GUSTAV. TEMPERATURES SHOULD FALL BELOW THE NORMAL ON WEDNESDAY... THURSDAY AND POSSIBLY FRIDAY...EDGING TOWARDS FALL LIKE WEATHER. AFTER INTENSE LOCAL COLLABORATION...WE UNDERCUT THE MAV GUIDANCE FOR TONIGHT THROUGH THURSDAY...FAVORING THE FWC AND MET VALUES. THERE IS STILL A POTENTIAL TO LOWER TEMPERATURES TONIGHT AND WEDNESDAY NIGHT BASED ON LOWER WIND SPEEDS AND LESS CLOUDS. NEXT ACTION OCCURS ON FRIDAY WHEN A COLD FRONT PUSHES THROUGH THE PANHANDLES. MODELS DIFFERED WITH THE TIMING THOUGH LEANED ON GFS AND ECMWF AGREEMENT AND RECENT PERFORMANCE. ANOTHER FRONT SWEEPS ACROSS THE PANHANDLES LATE SUNDAY/MONDAY. WE INTRODUCED CONSIDERABLE CLOUD COVER BUT KEPT IT DRY SINCE THE FORCING MAY STAY NORTH. NUNEZ FIRE WEATHER... SHOWERS AND THUNDERSTORMS WILL OCCUR TONIGHT AS THE INFLUENCES OF A RECENT COLD FRONT CONTINUE. COOLER AND DRIER AIR WILL PREVAIL ON WEDNESDAY THROUGH THURSDAY WHILE A HIGH PRESSURE SYSTEM SETTLES OVER THE PANHANDLES. NUNEZ && .AMA WATCHES/WARNINGS/ADVISORIES... TX...NONE. OK...NONE. && $$ 24/03 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER CO 315 AM MDT FRI SEP 5 2008 .SHORT TERM...WATER VAPOR IMAGERING SHOWING UPPER LEVEL TROF MOVING SE ACROSS SRN WYOMING ATTM. 80KT JET CORE NOSING INTO NW CO WHILE RUC QG VERTICAL VELOCITY FIELDS SHOWING MODEST ASCENT OVER NERN CO WITH THIS DISTURBANCE. CORRESPONDING 88D SHOWING MAIN SWAWTH OF BANDED PRECIP FROM LONGMONT TO NEW RAYMER BUT APPEARS TO BE WEAKENING WITH LACK OF SIGNIFIANT MSTR. THIS SWATH OF LIGHT TO MODERATE PRECIP WILL SAG SOUTHWARD A BIT OVER THE DENVER AREA BEFORE LIFTING EASTWARD DURING THE EARLY MORNING HOURS. THERE ARE STILL SOME SECONDARY AREAS OF SHOWERS ACROSS WY...SO WILL KEEP THE SCATTERED POPS THIS AM. AS THE TROF MOVES EAST...MOST OF THE PRECIP WILL END LATER THIS AM AS SUBSIDENCE MOVES INTO THE REGION AND UPSLOPE FLOW SHIFTS TO MORE SERLY THIS AFTN. THERE IS ANOTHER WEAK DISTURBANCE THAT CLIPS NERN CO LATER TNT WITH SOME WEAK ASCENT. BOTH GFS/NAM SHOWING SOME LIGHT QPF...ESP OVER THE FAR NERN CORNER. WILL ADD SOME LOW POPS FOR LATER TNT. .LONG TERM...THE FORECAST AREA IS UNDER NORTHWESTERLY FLOW ALOFT THROUGH SATURDAY NIGHT...THEN IT BECOMES WESTERLY SUNDAY. AN UPPER TROUGH STAYS TO OUR IMMEDIATE EAST AND NORTHEAST THROUGH MUCH OF THE TIME. A JET MAXIMUM NOSES ACROSS THE NORTHERN FORECAST AREA ON SATURDAY. THE BOUNDARY LAYER FLOW IS PROGGED TO BE UPSLOPE FOR THE PLAINS SATURDAY AFTERNOON INTO EARLY SUNDAY MORNING... EAST-SOUTHEASTERLY SUNDAY AND SUNDAY EVENING. THERE IS SOME LOW LEVEL MOISTURE OVER THE EASTERN FORECAST AREA SATURDAY MORNING. THERE IS ANOTHER BATCH OF LOW LEVEL MOISTURE FOR THE PLAINS LATE SATURDAY NIGHT INTO LATE SUNDAY MORNING. AFTER THAT MOISTURE DOESN`T GET IN HERE UNTIL MONDAY MORNING. THE ALPINE AREAS ARE FAIRLY DRY THROUGH MID DAY SUNDAY...THEN MOISTURE INCREASES A BIT. PRECIPITABLE WATER VALUES RANGE FROM 0.50 TO 0.80 INCH OVER THE PLAINS SATURDAY INTO SUNDAY EVENING. THERE IS A SLIGHT THETA-E AXIS OVER THE SOUTH CENTRAL AND SOUTHEAST FORECAST AREA ON SATURDAY. THERE IS ANOTHER ONE FOR SUNDAY OVER THE FOOTHILLS AND ADJACENT PLAINS. BOUNDARY LAYER DEW POINT VALUES ARE GENERALLY IN THE UPPER 30S TO UPPER 40S FOR THE PLAINS THROUGH ALL THE PERIODS. FOR CAPE ...THERE IS VERY LITTLE OVER THE FORECAST AREA SATURDAY AND SATURDAY NIGHT. BY LATE DAY SUNDAY...THERE IS SOME OVER THE FOOTHILLS AND ADJACENT PLAINS. THE QPF FIELDS SHOW VERY LITTLE MEASURABLE RAINFALL OVER THE FORECAST AREA THROUGH THE PERIODS. THE LAPSE RATE FIELDS SHOW SIGNIFICANT CAPS IN THE LOWER AND MID LEVELS FOR MUCH OF THE FORECAST AREA SATURDAY WELL INTO SUNDAY. THE HIGH COUNTRY AND IMMEDIATE PLAINS HAVE FAIRLY STEEP LAPSE RATES PROGGED FOR SUNDAY LATE IN THE DAY. FOR POPS...WILL LEAVE 0%S GOING SATURDAY INTO SUNDAY. WILL ADJUST SUNDAY AFTERNOON`S POPS TO JUST 10%S IN SOME OF THE MOUNTAINS...FOOTHILLS...AND IMMEDIATE PLAINS ONLY. FOR TEMPERATURES...SATURDAY`S HIGHS ARE 3-7 C WARMER THAN FRIDAY`S. SUNDAY`S COOL OFF A BIT...THE MOST OVER THE NORTHEAST CORNER. FOR THE LATER DAYS...MONDAY THROUGH THURSDAY...MODELS HAVE AN UPPER TROUGH MOVE ACROSS THE FORECAST AREA MONDAY MORNING...THEN ZONAL FLOW INTO WEDNESDAY...BEFORE ANOTHER UPPER TROUGH MOVES ACROSS LATER IN THE DAY INTO THURSDAY. A DECENT SURGE OF UPSLOPE IS PROGGED INTO THE PLAINS AND FOOTHILLS MONDAY MORNING. WILL MAKE FEW ADJUSTMENTS TO THESE LATER DAYS. && .AVIATION...LOCAL AIRPORTS WILL SEE VARYING CIGS THIS AM...AND EXPECT MVFR CIGS IN VCNTY OF SHOWERS. VFR CONDITIONS THIS AFTN AND TNT. NORTHEAST SFC WINDS WILL GRADUALLY SHIFT E-SE THIS AFTN. && .BOU WATCHES/WARNINGS/ADVISORIES...NONE. $$ SWE/RJK co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 359 AM CDT FRI SEP 5 2008 .DISCUSSION... FIRST IN A LONG SERIES OF WAVES IN THE PERSISTENT LONG WAVE TROF IS AFFECTING WESTERN KANSAS EARLY THIS MORNING. RADAR DATA INDICATED SHOWERS AND THUNDERSTORMS MOVING EASTWARD JUST AHEAD OF 700 MB TROF AXIS. RUC LOOKS PRETTY GOOD IN THE NEAR TERM...ALTHOUGH PRECIPITATION IS FALLING FURTHER EAST THAN THE PRECIPITATION DEPICTION FROM RUC. WARM ADVECTION MAY BE A BIT STRONGER THAN FORECAST BUT NOT TOO CONCERNED WITH RAPID ADVANCEMENT EAST OF THIS RAIN AS LAST EVENINGS SOUNDINGS WERE VERY DRY JUST OFF THE SURFACE. APPROACHING PRECIPITATION WILL TAKE AWHILE TO SATURATE AIRMASS. STILL...EXPECT PRECIP TO MAKE IT TO THE ENTIRE FORECAST AREA BY EARLY AFTERNOON. THE NEXT FEW DAYS ARE MESSY TO SAY THE LEAST. SEVERAL SHORTWAVES DEPICTED IN GFS/NAM/ECMWF. WITH PERSISTENT TROF ALOFT...EACH WEAK WAVE HAS ENOUGH UPPER DIVERGENCE TO INCREASE LOW LEVEL WARM ADVECTION AND ASSOCIATED ISENTROPIC LIFT. THE MAIN DIFFICULTY IS TIMING THIS PRECIPITATION POTENTIAL...AND HARDER EVEN IS TIMING THE DRY PERIODS. PREVIOUS FORECAST HAD LOW POP SOLUTION FOR ALL PERIODS THOUGH THE NEXT SEVERAL DAYS...AND HARD AS I TRY I AM UNABLE TO REDUCE TEMPORAL COVERAGE OF THESE POPS. THUS...PRETTY MUCH LEFT PREVIOUS FORECAST ALONE PAST SATURDAY. WILL DEFINITELY NEED WATCHING AS INDIVIDUAL WAVES ARE RESOLVED AND TIMING IS BETTER FORECAST. && .AVIATION... WITH CLEAR SKIES IN THE WAKE OF THE AFTERNOON STRATUS AND MOIST GROUND IN THE KFOE/KTOP...SHOULD CONTINUE TO SEE FOG DEVELOPING IN THESE SITES THROUGH 12Z. DRY AIR JUST OFF THE SFC SUPPORTS SHALLOW FOG AND THIS IN CONJUNCTION WITH SOME AC AND CIRRUS ARRIVING TOWARDS SUNRISE SHOULD SUPPORT A QUICK DISSIPATION TO THE FOG. DRIER GROUND...LOWER DEWPOINTS AND QUICKER ARRIVAL TO THE CLOUDS IN KMHK WAS THE REASON FOR KEEPING FOG OUT OF THE 06Z TAF...BUT WILL NEED TO BE MONITORED FOR ANY CHANGING TRENDS. WILL GO WITH IFR/LIFR VSBYS AT KFOE/KTOP...THEN IMPROVE TO VFR BETWEEN 13 AND 14Z WITH INCREASING AC CLOUDS AS NEXT WAVE APPROACHES WITH A FEW AFTERNOON SHOWERS IN THE KMHK AREA...BUT WITH VFR CIGS6-10KFT. AFTER THE WAVE PASSES BY 00Z...EXPECT LINGERING AC SCT-BKN100 AFTER 00Z. WINDS WILL REMAIN LIGHT THROUGH 06Z/SAT. && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ HARDING ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 358 AM EDT FRI SEP 5 2008 .SYNOPSIS... HIGH PRESSURE WILL START TO MOVE OUT OF THE REGION THIS MORNING. HANNA IS EXPECTED TO APPROACH THE SOUTHEAST COAST...MAKING LANDFALL ON THE SOUTHEAST COAST EARLY SATURDAY MORNING....BEFORE ACCELERATING NORTHEASTWARD TO ATLANTIC CANADA BY LATE SUNDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... CHANGES TO HEADLINES ANTICIPATED AFTER CONFERENCE CALL THIS MORNING WITH NHC. GFS/RUC IN DECENT AGREEMENT WITH RESPECT TO ENHANCED IR IMAGERY OF BANDING DVLMNT ON THE OUTER FRINGES OF HANNA. DECENT FORCING WITH HIGHER MOISTURE FLUX VALUES DVLPS AS OUTER BAND OF HANNA TO THE MOVES CLOSER TO THE CWA FROM THE SSE THIS MORNING. HIGHS TODAY MAINLY IN THE MID TO UPR 80S...WITH LOWER 80S NEAR/ALONG THE IMMEDIATE COASTLINE. FIRST OUTER BAND OF SHRAS/ISOL TSRA WILL LIKELY MOVE THROUGH THE CWA THIS AFTN/EVE WITH A DRY SLOT DVLPG BEHIND INITIAL BAND LATE EVE/ERLY OVRNT. LOOK FOR AN AVG OF A TENTH TO A QUARTER OF AN INCH WITH ITS PASSAGE...BUT SOME AREAS COULD SEE HIGHER AMOUNTS POSSIBLY NEARING AN INCH. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... GFS SHOWING A GOOD DEAL OF MOISTURE FLUX DIV DVLPG BTWN 03Z-14Z OVER SWRN 2/RDS OF THE CWA (S-N) AS INTERSECTION OF E-SE FLOW AT H92 CONVERGE. IN TURN THIS IS ALSO WHERE HIGHEST H70 THETA E VALUES ARE TO BE FCSTD. ALTHOUGH THIS IS PRETTY FAR NORTH OF THE CENTER OF HANNA THINK ENHANCED FORCING DVLPS AS ASSOC TRAILING FRONTAL BOUNDARY FROM GUSTAV TRIES TO APPROACH THE RGN FROM THE WEST. THIS IS FAIRLY A REASONABLE SCENARIO WHICH LATEST HPCQPF GUIDANCE IS ALSO IN AGREEMENT. DRYER AIR STARTS TO BECOME ENTRAINED INTO THE SYSTEM FROM THE SW AT MID LVLS AS SAT PROGRESSES PUSHING AREA OF HEAVIER RAINS TO OVER THE NNE SECTION OF THE CWA WITH TRAILING BAROCLINIC LEAF. ATTM...THINK BETWEEN 3-5 INCHES ON AVG WILL OCCUR OVER NWRN 2/3RDS OF THE CWA WITH HANNA (LOCALLY HIGHER AMOUNTS POSSIBLE WHERE ENHANCED BANDING DVLPS). WILL BE ISSUING A FLASH FLOOD WATCH WITH THIS PACKAGE. LITTLE MORE TRICKY WITH MORE OF A CONVECTIVE AIRMASS OVER THE ERN THIRD...WHICH WILL MAKE FOR MORE HIT AND MISS AREAS OF MOD/HVY RAINFALL. ATTM LOOKING AT AN AVG OF 1 TO 3 INCHES TO OCCUR (LOCALLY HIGHER/LOWER AMTS POSSIBLE). AS WITH ANY TROPICAL SYSTEM WITH HIGH 0-1KM SHEAR VALUES...LOOK FOR THE POTENTIAL FOR DAMAGING WINDS AND AN ENHANCED TORNADO THREAT TO DVLP LATE TONIGHT INTO SAT OVER SE THIRD OF THE CWA WITH OUTER RAIN BANDS. SEE LATEST SPC SWODY1 FOR MORE INFO. TROPICAL STORM FORCE WINDS WILL OCCUR OVER THE ERN THIRD OF THE CWA AS HANNA NEARS/PASSES THROUGH THE RGN. SUST WINDS OF 30-40 MPH WITH POTENTIAL GUST TO NEAR 60 MPH WILL OCCUR. FURTHER WEST...WILL ISSUE A TROPICAL STORM WIND WARNING (FOUND IN HLS) FOR ONE COUNTY BUFFER ZONE WEST OF THE CURRENT TROPICAL STORM WATCH/WRNGS HEADLINES TO ACCOUNT FOR GUSTS TO NEAR 40 MPH. FURTHER INLAND SUST WINDS WILL BE ON THE ORDER OF 10 TO 20 MPH WITH HIGHER GUSTS NEAR 35 MPH AT TIMES. PRECIP EVENTUALLY ENDS AS DRYER AIR FILTERS INTO THE RGN SAT NIGHT/SUN AM (SW-NE). && .LONG TERM /MONDAY THROUGH THURSDAY/... WEAK HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST ON MONDAY IN THE WAKE OF HANNA. MAINLY DRY CONDITIONS MON INTO TUE MRNG. MODELS/HPC HAVE TRENDED SLOWER WITH NEXT COLD FRONT NOW MAINLY LOOKING TO BE A TUE AFTN/EVENG EVENT. HAVE CONTD 30% CHC FOR SHWRS/TSTMS TUE/TUE NGT. THEN GOING DRY ON WED EXCEPT FOR LINGERING 20% POPS CLOSER TO STALLING BNDRY ACRS SOUTHERN ZONES. HIGH TEMPS WILL BE NEAR TO SLIGHTLY ABOVE AVG MON/TUE (MID/UPR 80S)...THEN A BIT COOLER (AT LEAST FOR DAYTIME HIGHS WED/THU WITH MORE CLOUD CVR EXPECTED....AND POSSIBLE APPROACH OF NEXT TROPICAL SYSTEM (IKE) FROM THE SE. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... VFR CNDTNS XCPT FOR LCL IFR AT SBY & ECG THRU 12Z FOR PTCHY FOG. OTW...TAF FCST WILL BE DOMINATED BY HANNA OVER NXT 24-36 HRS. HIGH/MID LVL CLD DECK OVRSPRDS RGN THIS AFTRN. MVFR CNDTNS XPCTD AFTR 21Z OR SO AS SHWRS SPREAD N FROM NC CSTL AREAS. ONLY PLACE I MENTIONED CB IS AT ECG LATE THIS AFTRN. CNDTNS RPDLY DETERIORATE THIS EVE AS IFR CNDTNS OVRSPRD RGN DUE TO RAIN / FOG. WNDS FIRST INCRS ALONG THE SERN CSTL TAF SITES WITH GUSTS AOA 25 KTS XPCTD B4 MIDNIGHT. GUSTY WNDS THEN SPREAD ACROSS RGN BY LATE TONITE. HANNA PROGGED TO MOVE RPDLY ACRS THE AREA SAT WITH GUSTY WNDS & OCNL IFR CIGS AND VSBYS. WINDS SAT NEAR THE COAST MAY REACH 25-35 WITH GUSTS TO 50 KNOTS AND OVER RIC IN THE 15-30 KNOT RANGE. CONDS WILL IMPROVE FROM S TO N LATE SAT AND SAT NIGHT. MAINLY VFR SHOULD PREVAIL INTO MID WEEK BUT A FEW SHOWERS MAY ACCOOMPANY THE NEXT COLD FRONT AROUND TUE. && .MARINE... TRPLCL HEADLINES REMAIN IN PLACE AS HANNA MOVES NE AND AFFECTS RGN FROM LATE TONIGHT THRU SAT EVE. WND GRIDS CONT TO FOLLOW TPC TRACK. WINDS STEADILY INCREASE TO TRPLCL STORM FORCE AFTR 06Z SAT STARTING OVER THE CURRITUCK SND/SRN COASTAL WATERS...THEN OVER THE SRN CHES BAY AND PRHAPS EVENTUALLY MAKING IT TO THE NRN COASTAL WATERS BY LATE MRNG/ERLY AFTN SAT. SEAS WILL ALSO BECOME VERY HAZARDOUS ON SAT...UP TO 11-15 FT OVER THE CSTL WATERS AND 4-5 FT OVER THE BAY...WITH MOUTH OF THE BAY WAVES APPRCHG 8 FT. STORM SURGE BTWN 2 TO 4 FEET ABV NRML TIDE LEVELS XPCTD...ALONG WITH LARGE AND DANGEROUS BATTERING WAVES XPCTD SAT ALONG THE BEACHES OF NORTHEAST NORTH CAROLINA. COASTAL FLOODING WILL BE GREATEST AROUND THE TIMES OF HIGH TIDE WHICH WILL OCCUR ERLY SAT AFTRN. HANNA RPDLY PULLS NE OF MARINE AREA LATER SAT NGT. IPROVING CNDTNS EXPCTD SUN. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...FLASH FLOOD WATCH FROM LATE TONIGHT THROUGH SATURDAY EVENING FOR MDZ021>023. TROPICAL STORM WATCH FOR MDZ021>025. NC...FLASH FLOOD WATCH FROM LATE TONIGHT THROUGH SATURDAY EVENING FOR NCZ012. TROPICAL STORM WIND WARNING FROM 2 AM TO 2 PM EDT SATURDAY FOR NCZ012>014. TROPICAL STORM WARNING FOR NCZ015>017-030>032-102. VA...FLASH FLOOD WATCH FROM LATE TONIGHT THROUGH SATURDAY EVENING FOR VAZ048-049-060>090-092. TROPICAL STORM WATCH FOR VAZ075-077-078-084>086-089>091- 093>100. TROPICAL STORM WIND WARNING FROM 2 AM TO 2 PM EDT SATURDAY FOR VAZ072>074-076-081>083-088-092. MARINE...TROPICAL STORM WATCH FOR ANZ630>632-650-652-654-656. TROPICAL STORM WARNING FOR ANZ633-658. && $$ SYNOPSIS...CCW NEAR TERM...CCW SHORT TERM...CCW LONG TERM...LKB AVIATION...MPR MARINE...MPR md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GLASGOW MT 406 AM MDT FRI SEP 5 2008 .SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH SUNDAY... NOT MUCH CHANGE IN THE LONGWAVE PATTERN THRU THE WEEKEND...WITH UPPER RIDGING OFF THE W COAST...UPPER TROUGHING OVER THE MIDWEST. NE MT IS ON THE BACKSIDE OF TROUGH IN NW FLOW...WITH THE JETSTREAM REMAINING STRONGER AND FARTHER S THAN USUAL FOR EARLY SEP. THIS MORN...SOME LOCATIONS SHOW OBS THAT ARE NEARLY SATURATED. THIS NOT AS EXTENSIVE AS YESTERDAY THOUGH. RUC SHOWS 95 PCT RH ACROSS ROUGHLY OUR NE QUARTER AT 12Z. WILL COMBINE THIS WITH THE OBS THAT HAVE BEEN REPORTING TEMP/DEW POINT SPREADS OF 0-2F AT 3 AM TO ADD PATCHY EARLY MORN FOG MENTION. THIS WILL BE IN LOWER MILK...MISSOURI...AND BIG MUDDY RIVER VALLEYS. OTHERWISE... GENERALLY CLEAR SKIES EARLY THIS MORN...BUT IR SATELLITE CHANNEL SHOWS A RATHER LARGE AREA OF MID-LEVEL OVERCAST IN AB AND NC/NW MT THAT WILL BE MOVING ACROSS OUR N THIS MORN. NO PRECIP EXPECTED FROM IT. OTHERWISE MORE SUNSHINE WILL ALLOW A FEW DEGREES WARMING OVER YESTERDAY. AIRMASS SLIGHTLY DRIER AND SLIGHTLY LESS UNSTABLE FOR THE AFTERNOON WITHOUT ANY SHORTWAVES. THIS SHOULD LIMIT SHOWER DEVELOPMENT TO LESS THAN YESTERDAY...BUT THERE WILL BE A FEW WEAK CELLS...MAINLY E. WILL GO WITH POPS LOW ENOUGH THAT THEY WON`T SHOW AS WORDING IN TEXT PRODUCTS. MODELS CONTINUE TO BRING A MODERATE SHORTWAVE FROM THE NW ACROSS THE AREA LATE TONIGHT AND SAT FOR SCATTERED SHOWERS. ALL MODELS SHOW A FAIR AREA OF QPF. THE SYSTEM DOESN`T APPEAR ALL THAT WELL ORGANIZED...SO WILL KEEP POPS IN SCATTERED CATEGORY...BUT KEEPING IN MIND ALSO THAT TYPICALLY THESE SYSTEMS FROM THE NW ARE OFTEN UNDERFORECAST FOR POPS. WITH 850 MB WINDS TO 20KT OR SO WITH WEAK COOL ADVECTION IN THE AFTERNOON...WILL BE NEAR LAKE WIND ADVISORY CRITERIA SAT. SKIES CLEAR ACROSS OUR N SAT NIGHT. THICKNESSES DROP TO AROUND 543 DM AND 850 TEMPS TO 5C. THIS IS AT LEAST AS LOW AS THE PREVIOUS FEW COOL NIGHTS. WITH SURFACE HIGH OVER AREA AND DEW POINTS LOWER THAN LATELY...WOULD EXPECT WIDESPREAD 30S FOR LOWS...SOME TO AROUND FREEZING IN THE TYPICAL COLDEST POCKETS. MEANWHILE.. INCREASING CLOUDS IN OUR S. MODELS VARY QUITE A BIT ON INTENSITY...BUT ALL HAVE A SHORTWAVE MOVE SE ALONG THE JETSTREAM THRU THE MIDDLE OF THE STATE LATE SAT NIGHT AND SUN. THESE OFTEN DO AFFECT OUR SW...BUT SELDOM ELSEWHERE AS FAR AS PRECIP GOES. WILL GO WITH A CHANCE OF RAIN SUN IN OUR SW. PREFER TO GO A LITTLE BELOW MOS ALL AREAS SUN AS WELL. SIMONSEN .LONG TERM...SUNDAY NIGHT THROUGH FRIDAY... NORTHWEST FLOW ALOFT WILL CONTINUE OVER THE FORECAST AREA MOST OF THE TIME THROUGH THE PERIOD. LOOK FOR DRY WEATHER AND A WARMING TREND WITH A SURFACE HIGH ON MONDAY AND A SHORTWAVE UPPER RIDGE ON TUESDAY. MODELS HAVE HAD SOME DIFFERENCES ON TRACKING A MIDWEEK SHORTWAVE TROUGH AND COLD FRONT. 00Z GFS...00Z CANADIAN AND 12Z ECMWF HAD THE FRONT AND SHORTWAVE AFFECTING THE FORECAST AREA ON WEDNESDAY. 00Z ECMWF HAS SLOWED IT DOWN. THE LAST 3 RUNS OF THE GFS HAVE HAD THE MAIN PART OF THE WAVE AFFECTING NE MONTANA EITHER WEDNESDAY OR WEDNESDAY NIGHT WITH THE COLD FRONT FORECASTED FOR WEDNESDAY FOR SEVERAL RUNS. WILL MAINTAIN A WED FRONTAL PASSAGE AND MENTION A SLIGHT CHANCE OF THUNDERSTORMS ON WED AND SHOWERS WED NIGHT. NORTHWEST FLOW ALOFT WILL PREVAIL AFTER THE TROUGH EXITS WITH MAINLY DRY WEATHER. FORRESTER && .AVIATION... VFR CONDITIONS ARE EXPECTED TO PREVAIL MOST OF THE TIME TODAY AND TONIGHT. FOG REMAINS A SLIGHT POSSIBILITY THIS MORNING...WITH THE MOST LIKELY SITES BEING KOLF AND KSDY. BROKEN CUMULUS AROUND 4K OR 5K FT AGL IS EXPECTED THIS AFTERNOON INTO EARLY EVENING. NORTHWEST WIND WILL BE AROUND 10 KT TODAY. LOOK FOR EITHER MID LEVEL OR LOW VFR CEILINGS TO PREVAIL TONIGHT WITH A CHANCE OF RAIN. && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WEATHER.GOV/GLASGOW mt AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 714 AM CDT FRI SEP 5 2008 .UPDATE... FORECAST AND AVIATION UPDATE. && .DISCUSSION... DID A QUICK UPDATE TO POPS/WX...TO EXTEND EASTERN EDGE OF POPS THIS MORNING AND INCREASE COVERAGE A BIT TO BLEND WITH NEIGHBORS THIS AFTERNOON. NOT EXPECTING MUCH BESIDES SHOWERS LACKING INSTABILITY IN THE SOUNDINGS. MAY TAKE A BIT FOR COLUMN TO SATURATE CONSIDERING DRY AIR AT THE SURFACE. && .AVIATION... MONITORING VISBYS AT TOP AND FOE ATTM. EXPECT 1/2SM VISBYS TO BREAK UP BY 14Z AS SUN COMES UP. WINDS LIGHT AND VARIABLE THIS MORNING UNTIL WEAK FRONTAL BOUNDARY PUSHES THROUGH IN THE AFTERNOON AND BRINGS A NORTHERLY COMPONENT TO THE WINDS. HAVE VCSH IN TAF SITES WAITING TO SEE IF DRY AIR EVAPS SHOWERS BEFORE THEY HIT THE GROUND. WILL PROBABLY NEED A PREVAILING -SHRA GROUP AT SOME POINT THIS AFTERNOON. 67 && .PREV DISCUSSION... /ISSUED 359 AM CDT FRI SEP 5 2008/ DISCUSSION... FIRST IN A LONG SERIES OF WAVES IN THE PERSISTENT LONG WAVE TROF IS AFFECTING WESTERN KANSAS EARLY THIS MORNING. RADAR DATA INDICATED SHOWERS AND THUNDERSTORMS MOVING EASTWARD JUST AHEAD OF 700 MB TROF AXIS. RUC LOOKS PRETTY GOOD IN THE NEAR TERM...ALTHOUGH PRECIPITATION IS FALLING FURTHER EAST THAN THE PRECIPITATION DEPICTION FROM RUC. WARM ADVECTION MAY BE A BIT STRONGER THAN FORECAST BUT NOT TOO CONCERNED WITH RAPID ADVANCEMENT EAST OF THIS RAIN AS LAST EVENINGS SOUNDINGS WERE VERY DRY JUST OFF THE SURFACE. APPROACHING PRECIPITATION WILL TAKE AWHILE TO SATURATE AIRMASS. STILL...EXPECT PRECIP TO MAKE IT TO THE ENTIRE FORECAST AREA BY EARLY AFTERNOON. THE NEXT FEW DAYS ARE MESSY TO SAY THE LEAST. SEVERAL SHORTWAVES DEPICTED IN GFS/NAM/ECMWF. WITH PERSISTENT TROF ALOFT...EACH WEAK WAVE HAS ENOUGH UPPER DIVERGENCE TO INCREASE LOW LEVEL WARM ADVECTION AND ASSOCIATED ISENTROPIC LIFT. THE MAIN DIFFICULTY IS TIMING THIS PRECIPITATION POTENTIAL...AND HARDER EVEN IS TIMING THE DRY PERIODS. PREVIOUS FORECAST HAD LOW POP SOLUTION FOR ALL PERIODS THOUGH THE NEXT SEVERAL DAYS...AND HARD AS I TRY I AM UNABLE TO REDUCE TEMPORAL COVERAGE OF THESE POPS. THUS...PRETTY MUCH LEFT PREVIOUS FORECAST ALONE PAST SATURDAY. WILL DEFINITELY NEED WATCHING AS INDIVIDUAL WAVES ARE RESOLVED AND TIMING IS BETTER FORECAST. && .TOP WATCHES/WARNINGS/ADVISORIES...DENSE FOG ADVISORY UNTIL 10 AM FRIDAY FOR KSZ026-KSZ039-KSZ040-KSZ054-KSZ055-KSZ056-KSZ058-KSZ059. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 937 AM CDT FRI SEP 5 2008 .UPDATE... SMALL UPDATES TO ACCOUNT FOR SOME LOCALIZED FOG ACROSS PARTS OF RANGE/SRN WI ZONES. ADDITIONALLY... SLOWER PROGRESSION OF POPS/QPF/CLOUDS INTO NE ARROWHEAD AND ERN WI ZONES. LINEAR BAND OF RAIN ASSOCIATED WITH SFC/925 THETAE AXIS AHEAD OF APPROACHING LOW. USING LATEST RUC13...THIS LOW LVL INSTABILITY AXIS MOVES VERY SLOWLY EAST TODAY...WITH A TENDENCY TO STRENGTHEN OVER SCTRL WIS ZONES LATE THIS AFTERNOON. MAY SEE SOME CONVECTION DEVELOP OVER THIS REGION LATER TODAY AS MDLS SUGGEST BEST 85H MSTR TRANSPORT WILL PUSH INTO WISCONSIN. NAM40 FCST SBCAPE VALUES RANGE BETWEEN 500/1000 J/KG WITH 0-6KM SHEAR OF 35/40KTS. && .PREV DISCUSSION... /ISSUED 247 AM CDT FRI SEP 5 2008/ DISCUSSION... SFC STATIONS REPORTING PATCHY FG THIS MORNING WITH GENERALLY LIGHT E TO SE WINDS. WEAK SFC LOW/TROUGH...CO-LOCATED WITH A POTENT SHORT WAVE SEEN ON IR IMAGERY ROTATING OVER NE NO DAK...PUSHES E INTO WRN MN. MOSAIC RADAR SHOWS THE VORT MAX/SFC LOW HAS BROUGHT SHRA TO NE NO DAK/NW MN OVERNIGHT...WITH THE LEADING EDGE CURRENTLY NEAR BJI LIFTING NORTH AND EAST. MODELS CONTINUE TO BE IN GOOD AGREEMENT AND HAVE KEPT RUN TO RUN CONTINUITY. THE SYSTEM WILL PROGRESS EWRD OVER THE WRN GREAT LAKES REGION TODAY AND TONIGHT. THE BEST LIFT AND INSTABILITY WILL BE FOUND OVER THE IRON RANGE AND INTO ADJACENT SRN CANADA...WITH WEAKER FORCING IN THE SRN ZONES. INCREASED POPS TO LIKELY ACROSS THE NRN TIER OF COUNTIES TODAY...WITH DECREASING POPS SOUTH AND EAST. QPF AMOUNTS WILL BE SCT AND GENERALLY LIGHT...RANGING FROM A FEW HUNDREDTHS TO AROUND A TENTH. KEPT ISOLD TSRA WORDING THIS AFTRN. BUFR SOUNDINGS SUGGEST FAVORABLE MID LVL LAPSE RATES WITH A FEW HUNDRED J OF CAPE DEVELOP THIS AFTN TO SUPPORT ISOLD -TSRA THIS AFTN...REMAINING WELL BLW SVR LVLS. THE FA WILL REMAIN UNDER THE CYCLONIC CURVATURE OF THE BROAD UPR LVL TROUGH THROUGH SAT. KEPT THE 20-30 POP FOR SHRA THROUGH THIS TIME FRAME. ANOTHER LOBE OF ENERGY ROUNDS THE BASE OF THE UPR LVL TROUGH OVER MN AND THE WRN GREAT LKS REGION LATE SAT NIGHT THROUGH SUNDAY NIGHT...CONTINUING THE CHC FOR SHRA. AVIATION...A SHORTWAVE WILL PUSH EAST ACROSS THE AREA TODAY...AND WHILE MAINLY VFR CONDITIONS CAN BE EXPECTED...SOME TEMPO MVFR-IFR CEILINGS MAY OCCUR IN SCATTERED SHOWERS THROUGHOUT MUCH OF THE DAY. THE MOST PERSISTENT AND WIDESPREAD SHOWERS WILL BE CONFINED TO THE FAR NORTHWEST PORTION OF THE AREA...INCLUDING KINL...WHERE THE BEST OMEGA AND VORTICITY ADVECTION WILL BE FOUND. SOME THUNDER IS CERTAINLY POSSIBLE ACROSS THE ENTIRE AREA...ESPECIALLY AFTER 14Z...BUT IT SHOULD REMAIN RATHER ISOLATED AS INSTABILITY PARAMETERS ARE WEAK. WITH A DEPARTING HIGH TO THE NORTH...A NORTHEAST FLOW WILL RESULT IN LOW CLOUDS NEAR LAKE SUPERIOR...ESPECIALLY AT KDLH...THROUGH MID-MORNING. PATCHY FOG AND LOCAL IFR-VLIFR CONDITIONS MAY ALSO OCCUR IN PORTIONS OF NORTHWEST WISCONSIN THROUGH ABOUT 14Z TODAY. DEWPOINTS HAVE RISEN IN THESE AREAS...AND FORECAST SOUNDINGS DO SHOW THE DEVELOPMENT OF STRATUS AND FOG FOR THE MORNING HOURS. AS THE SFC LOW WEAKENS AND BECOMES MORE OF A BROAD TROUGH...THE CHANCE FOR SHOWERS WILL LESSEN AS THE SHORTWAVE PUSHES EAST...WITH ONLY ISOLATED-SCATTERED SHOWERS FOR KHYR THIS AFTERNOON. CONDITIONS WILL IMPROVE IN ALL AREAS AFTER 00Z...WITH JUST SOME REMNANT SCATTERED CLOUDS. && POINT TEMPS/POPS... DLH 64 47 71 47 / 30 20 30 30 INL 64 46 67 40 / 70 20 30 40 BRD 65 45 68 46 / 20 10 20 40 HYR 68 45 70 43 / 20 30 20 30 ASX 65 48 69 44 / 20 30 30 30 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. $$ CANNON mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GLASGOW MT 943 AM MDT FRI SEP 5 2008 .SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH SUNDAY... ONLY MINOR UPDATE TO CLOUD COVER FOR TODAY. ALSO FOR END OF PATCHY FOG. SHORTWAVE ENERGY PUSHING MOISTURE INTO CENTRAL MONTANA WITH CLOUDS NUDGING TOWARD EASTERN MONTANA. AIRMASS NOT AS UNSTABLE AS YESTERDAY SO AFTERNOON SHOWERS ARE LESS LIKELY THIS AFTERNOON THAN YESTERDAY. ALSO MORE SUNSHINE...SO EXPECT SLIGHTLY WARMER TEMPERATURES AS WELL. EBERT PREVIOUS SHORT TERM DISCUSSION...NOT MUCH CHANGE IN THE LONGWAVE PATTERN THRU THE WEEKEND...WITH UPPER RIDGING OFF THE W COAST...UPPER TROUGHING OVER THE MIDWEST. NE MT IS ON THE BACKSIDE OF TROUGH IN NW FLOW...WITH THE JETSTREAM REMAINING STRONGER AND FARTHER S THAN USUAL FOR EARLY SEP. THIS MORN...SOME LOCATIONS SHOW OBS THAT ARE NEARLY SATURATED. THIS NOT AS EXTENSIVE AS YESTERDAY THOUGH. RUC SHOWS 95 PCT RH ACROSS ROUGHLY OUR NE QUARTER AT 12Z. WILL COMBINE THIS WITH THE OBS THAT HAVE BEEN REPORTING TEMP/DEW POINT SPREADS OF 0-2F AT 3 AM TO ADD PATCHY EARLY MORN FOG MENTION. THIS WILL BE IN LOWER MILK...MISSOURI...AND BIG MUDDY RIVER VALLEYS. OTHERWISE... GENERALLY CLEAR SKIES EARLY THIS MORN...BUT IR SATELLITE CHANNEL SHOWS A RATHER LARGE AREA OF MID-LEVEL OVERCAST IN AB AND NC/NW MT THAT WILL BE MOVING ACROSS OUR N THIS MORN. NO PRECIP EXPECTED FROM IT. OTHERWISE MORE SUNSHINE WILL ALLOW A FEW DEGREES WARMING OVER YESTERDAY. AIRMASS SLIGHTLY DRIER AND SLIGHTLY LESS UNSTABLE FOR THE AFTERNOON WITHOUT ANY SHORTWAVES. THIS SHOULD LIMIT SHOWER DEVELOPMENT TO LESS THAN YESTERDAY...BUT THERE WILL BE A FEW WEAK CELLS...MAINLY E. WILL GO WITH POPS LOW ENOUGH THAT THEY WON`T SHOW AS WORDING IN TEXT PRODUCTS. MODELS CONTINUE TO BRING A MODERATE SHORTWAVE FROM THE NW ACROSS THE AREA LATE TONIGHT AND SAT FOR SCATTERED SHOWERS. ALL MODELS SHOW A FAIR AREA OF QPF. THE SYSTEM DOESN`T APPEAR ALL THAT WELL ORGANIZED...SO WILL KEEP POPS IN SCATTERED CATEGORY...BUT KEEPING IN MIND ALSO THAT TYPICALLY THESE SYSTEMS FROM THE NW ARE OFTEN UNDERFORECAST FOR POPS. WITH 850 MB WINDS TO 20KT OR SO WITH WEAK COOL ADVECTION IN THE AFTERNOON...WILL BE NEAR LAKE WIND ADVISORY CRITERIA SAT. SKIES CLEAR ACROSS OUR N SAT NIGHT. THICKNESSES DROP TO AROUND 543 DM AND 850 TEMPS TO 5C. THIS IS AT LEAST AS LOW AS THE PREVIOUS FEW COOL NIGHTS. WITH SURFACE HIGH OVER AREA AND DEW POINTS LOWER THAN LATELY...WOULD EXPECT WIDESPREAD 30S FOR LOWS...SOME TO AROUND FREEZING IN THE TYPICAL COLDEST POCKETS. MEANWHILE.. INCREASING CLOUDS IN OUR S. MODELS VARY QUITE A BIT ON INTENSITY...BUT ALL HAVE A SHORTWAVE MOVE SE ALONG THE JETSTREAM THRU THE MIDDLE OF THE STATE LATE SAT NIGHT AND SUN. THESE OFTEN DO AFFECT OUR SW...BUT SELDOM ELSEWHERE AS FAR AS PRECIP GOES. WILL GO WITH A CHANCE OF RAIN SUN IN OUR SW. PREFER TO GO A LITTLE BELOW MOS ALL AREAS SUN AS WELL. SIMONSEN .LONG TERM...SUNDAY NIGHT THROUGH FRIDAY... NORTHWEST FLOW ALOFT WILL CONTINUE OVER THE FORECAST AREA MOST OF THE TIME THROUGH THE PERIOD. LOOK FOR DRY WEATHER AND A WARMING TREND WITH A SURFACE HIGH ON MONDAY AND A SHORTWAVE UPPER RIDGE ON TUESDAY. MODELS HAVE HAD SOME DIFFERENCES ON TRACKING A MIDWEEK SHORTWAVE TROUGH AND COLD FRONT. 00Z GFS...00Z CANADIAN AND 12Z ECMWF HAD THE FRONT AND SHORTWAVE AFFECTING THE FORECAST AREA ON WEDNESDAY. 00Z ECMWF HAS SLOWED IT DOWN. THE LAST 3 RUNS OF THE GFS HAVE HAD THE MAIN PART OF THE WAVE AFFECTING NE MONTANA EITHER WEDNESDAY OR WEDNESDAY NIGHT WITH THE COLD FRONT FORECASTED FOR WEDNESDAY FOR SEVERAL RUNS. WILL MAINTAIN A WED FRONTAL PASSAGE AND MENTION A SLIGHT CHANCE OF THUNDERSTORMS ON WED AND SHOWERS WED NIGHT. NORTHWEST FLOW ALOFT WILL PREVAIL AFTER THE TROUGH EXITS WITH MAINLY DRY WEATHER. FORRESTER && .AVIATION... VFR CONDITIONS ARE EXPECTED TO PREVAIL TODAY INTO THIS EVENING. BROKEN CUMULUS AROUND 4K OR 5K FT AGL IS EXPECTED THIS AFTERNOON INTO EARLY EVENING. NORTHWEST WIND WILL BE AROUND 10 KT TODAY. LOOK FOR EITHER MID LEVEL OR LOW VFR CEILINGS TO PREVAIL LATER TONIGHT WITH A CHANCE OF RAIN THAT WILL CONTINUE THROUGH SATURDAY. FRANSEN && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WEATHER.GOV/GLASGOW mt AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 1250 PM CDT FRI SEP 5 2008 .UPDATE... UPDATE FOR 18 UTC AVIATION. && .DISCUSSION... SEE PREVIOUS DISCUSSION. && .AVIATION... DRY MID LEVELS PER 12Z TOP SOUNDING MAKING PRECIPITATION DIFFICULT TO REACH THE GROUND. MAY SEE CEILINGS AND VISIBILITIES BRIEFLY DROP TO MVFR RANGE...BUT SEE LITTLE JUSTIFICATION FOR INCLUSION GIVEN PRECIPITATION COVERAGE. SHOULD SEE A BREAK IN SIGNIFICANT WEATHER THIS EVENING...BUT LIGHT WINDS AND RESIDUAL LOW LEVEL MOISTURE MAY ALLOW FOR BR DEVELOPMENT AROUND OVERNIGHT INTO EARLY SATURDAY. NEXT PRECIPITATION CHANCES COME IN BY LATE SATURDAY MORNING. && .PREV DISCUSSION... /ISSUED 359 AM CDT FRI SEP 5 2008/ DISCUSSION... FIRST IN A LONG SERIES OF WAVES IN THE PERSISTENT LONG WAVE TROF IS AFFECTING WESTERN KANSAS EARLY THIS MORNING. RADAR DATA INDICATED SHOWERS AND THUNDERSTORMS MOVING EASTWARD JUST AHEAD OF 700 MB TROF AXIS. RUC LOOKS PRETTY GOOD IN THE NEAR TERM...ALTHOUGH PRECIPITATION IS FALLING FURTHER EAST THAN THE PRECIPITATION DEPICTION FROM RUC. WARM ADVECTION MAY BE A BIT STRONGER THAN FORECAST BUT NOT TOO CONCERNED WITH RAPID ADVANCEMENT EAST OF THIS RAIN AS LAST EVENINGS SOUNDINGS WERE VERY DRY JUST OFF THE SURFACE. APPROACHING PRECIPITATION WILL TAKE AWHILE TO SATURATE AIRMASS. STILL...EXPECT PRECIP TO MAKE IT TO THE ENTIRE FORECAST AREA BY EARLY AFTERNOON. THE NEXT FEW DAYS ARE MESSY TO SAY THE LEAST. SEVERAL SHORTWAVES DEPICTED IN GFS/NAM/ECMWF. WITH PERSISTENT TROF ALOFT...EACH WEAK WAVE HAS ENOUGH UPPER DIVERGENCE TO INCREASE LOW LEVEL WARM ADVECTION AND ASSOCIATED ISENTROPIC LIFT. THE MAIN DIFFICULTY IS TIMING THIS PRECIPITATION POTENTIAL...AND HARDER EVEN IS TIMING THE DRY PERIODS. PREVIOUS FORECAST HAD LOW POP SOLUTION FOR ALL PERIODS THOUGH THE NEXT SEVERAL DAYS...AND HARD AS I TRY I AM UNABLE TO REDUCE TEMPORAL COVERAGE OF THESE POPS. THUS...PRETTY MUCH LEFT PREVIOUS FORECAST ALONE PAST SATURDAY. WILL DEFINITELY NEED WATCHING AS INDIVIDUAL WAVES ARE RESOLVED AND TIMING IS BETTER FORECAST. && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ HARDING/65 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 325 PM EDT FRI SEP 5 2008 .SYNOPSIS... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW UPR TROFFING CENTERED OVER CNTRL NAMERICA BTWN RDGS ON THE E AND W COASTS. SHRTWV/DEEP MSTR ASSOCIATED WITH THE REMNANTS OF GUSTAV ARE MOVING RDPLY NE THRU SE CAN...BUT A SUBTLE LO PRES TROF REMAINS OVER THE FA ON ITS WRN FLANK. RECENT TAMDAR SDNGS SHOW A GOOD AMT OF LLVL MSTR REMAINS OVER THE UPR GRT LKS UNDER THE SUBSIDENCE INVRN ARND H75 LEFT IN ITS WAKE. SO QUITE A BIT OF SC IS PRESENT DESPITE DIURNAL HTG THAT HAS LIFTED CLD BASE AND ENDED ANY -DZ THAT WAS OBSVD EARLIER. THE COMBINATION OF SOME SUBSIDENCE OVER LK SUP RELATED TO THE LK BREEZE CIRCULATION AND THE ARRIVAL OF SOMEWHAT DRIER AIR FM THE NW THAT WAS SHOWN BEST ON THE 00Z RAOBS FM INL/YPL HAS TENDED TO BREAK UP THE CLD MORE AGGRESSIVELY THERE AND NEAR THE LK SHORES. NEXT SHRTWV OF CONCERN IS PRESENTLY MOVING ACRS NRN MN ALONG WITH AN ASSOCIATED SFC LO. THERE IS QUITE A BIT OF CLD TO THE N AND W OF THIS LO...AND THE ERN EDGE OF THE THICKER CLD IS MOVING TOWARD WRN LK SUP. SOME SCT -SHRA ARE AS FAR E AS DLH IN AXIS OF HIER SPECIFIC HUMIDITY SHOWN ON THE 300K ISENTROPIC SFC (ARND H7) BY THE 12Z NAM F6. BUT OVERALL PCPN COVG SEEMS LIMITED BY THE DRY MID LVLS SHOWN ON THE 12Z MPX RAOB. && .SHORT TERM DISCUSSION (TNGT AND SAT)... FOR TNGT...12Z GFS/NAM SHOW SHRTWV NOW OVER NRN MN SHEARING ENEWD AND WEAKENING A BIT TO NEAR ISLE ROYALE BY 12Z SAT AS UPR TROF AXIS REMAINS SITUATED IN THE PLAINS. THE ACCOMPANYING SFC LO IS PROGGED TO REACH THE WRN SHORE OF THE U.P. BOTH MODELS SHOW AXIS OF HIEST SPECIFIC HUMIDITY NOW OVER MN AND ON THE 300K SFC SHIFTING INTO THE W THIS EVNG THEN THE ECNTRL BY 12Z SAT WITH ISENTROPIC LIFT NOTED ON THE 295-305K SFCS/QVECTOR CNVGC IN THE H85-5 LYR. GFS IS A BIT MORE GENEROUS WITH QPF...BUT PREFER THE SOMEWHAT MORE MODEST NAM GIVEN THE MID LVL DRY AIR SHOWN ON THE 12Z MPX RAOB THAT IS LIMITING PCPN COVG NOW. STILL...HAVE OPTED TO BUMP POPS UP TO 40 BEFORE FAIRLY AGGRESSIVE DRYING ON THE 300K SFC IN THE JET SURGE REGION ON THE SE FLANK OF THE SHRTWV TRACK OVERSPRDS THE FA. GOING FCST MIN TEMPS ARE FAIRLY IN LINE WITH LATEST GFS/ETA/NGM MOS GUIDANCE...SO NO SGNFT CHGS MADE TO GOING FCST. ON SAT...THE DEEPER MSTR ALF WL IMPACT THE ERN ZNS IN THE MRNG BEFORE THE DRYING ON THE 300K SFC IS FCST TO CLR ERY BY 18Z OR SO AS THE SHRTWV NR ISLE ROYALE/SFC LO OVER WRN LK SUP AT 12Z SHIFTS NE INTO ONTARIO. TO THE W...THE FOCUS SHIFTS TO WHETHER ENUF LLVL MSTR WL LINGER TO ALLOW THE REDVLPMNT OF MORE SHRA WITH DIURNAL HTG. IF THE TIME OF YEAR WERE CLOSER TO THE SUMMER SOLSTICE...THAT WOULD BE A REAL CONCERN. OTHER CONSIDERATIONS INCLUDE THE PRESENCE OF LINGERING LO CLD IN THE MRNG WHICH DVLPS WITH THE ARRIVAL OF THE DRYING ALF LATE TNGT AND THAT WOULD LIMIT SFC HTG. CONSIDERING THE MARGINAL LAPSE RATES AND MID LVL DRY AIR EXHIBITED IN GFS/NAM FCST SDNGS IN THE ABSENCE OF DYNAMIC FORCING...BELIEVE REDVLPMNT OF DIURNAL SHRA IN THE AFTN IS A LO POTENTIAL. SO ELECTED TO CUT GOING GENERAL 30 POP TO NO MORE THAN 20. && .LONG TERM (SATURDAY NIGHT THROUGH FRIDAY)... THIS PERIOD REMAINS PLAGUED BY WEAK SHORTWAVES...MAKING SPECIFIC TIMING OF CLOUDS AND PRECIPITATION DIFFICULT. FOR THE LONG TERM THIS RESULTS IN AVERAGE FORECASTER CONFIDENCE IN THE SPECIFICS. LINGERING PRECIPITATION WILL START OFF THIS PERIOD THANKS TO A WEAK SHORTWAVE MOVING THROUGH THE CWA. A SLIGHTLY STRONGER SYSTEM IS FIGURED FOR SUNDAY AND SUNDAY NIGHT...MOVING THROUGH THE UPPER GREAT LAKES. THE POTENTIAL REMAINS FOR THUNDERSTORM ACTIVITY...ALBEIT ISOLATED. A COLD FRONT WILL BE POISED TO MOVE WEST TO EAST OVER UPPER MICHIGAN LATE SUNDAY AFTERNOON THROUGH THE EARLY OVERNIGHT HOURS. THE ENTIRE SYSTEM IS THEN EXPECTED TO STRENTHEN OVER SOUTHEASTERN ONTARIO AND LAKE HURON MONDAY MORNING. THIS SHOULD KEEP NORTH TO NORTHWESTERLY WINDS AND A BETTER CHANCE OF LINGERING CLOUDS ACROSS EASTERN UPPER MICHIGAN INTO AT LEAST MONDAY AFTERNOON. DRY WEATHER CAN THEN BE EXPECTED FOR THE MIDDLE OF THE UPCOMING WORK WEEK...AS HIGH PRESSURE MOVES IN AT THE SURFACE AND A ZONAL FLOW SETS UP AT 500MB. HPC GUIDANCE WAS FOLLOWED PRETTY CLOSELY FOR THIS PERIOD...EXCLUDING SKY COVER WHICH NEEDED TO BE MINIMIZED A LITTLE MORE INITIALLY. THIS WAS HEAVILY BASED ON ENSEMBLES...WITH A LEAN TOWARDS THE 12Z GFS. FOR THE LATTER HALF OF THE WORK WEEK THOUGH...SOUTHWESTERLY FLOW WILL RETURN BRINGING A BETTER CHANCE OF SHOWERS OR THUNDERSTORMS THURSDAY AND FRIDAY. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... EXPECT VFR CONDITIONS TO PREVAIL INTO TNGT WITH WEAK HI PRES RDG DOMINATING. SOME SHRA WL ARRIVE LATER TNGT AS A LOW PRES MOVES FM MN INTO WRN LK SUP. ALTHOUGH VFR CONDITIONS ARE LIKELY WHEN THE RA ARRIVES...MVFR CONDITIONS WITH LO CLD/FOG WL DVLP TOWARD WHEN THE RA ENDS WITH THE ARRIVAL OF DRIER AIR ALF ABV THE LLVLS MOISTENED BY THE PCPN AND DIURNAL COOLING. THERE WL BE ONLY GRADUAL IMPROVEMENT ON SAT MRNG. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... LOW PRESSURE OVER FAR WESTERN QUEBEC WILL WEAKEN AS IT MOVES OVER NEW BRUNSWICK SATURDAY MORNING WHILE A HIGH PRESSURE RIDGE OVER WESTERN LAKE SUPERIOR THIS EVENING MOVES OVER THE EASTERN GREAT LAKES ON SUNDAY. MEANWHILE...A TROUGH OF LOW PRESSURE WILL CROSS LAKE SUPERIOR SATURDAY. ANOTHER DEEPER LOW PRESSURE TROUGH WILL FOLLOW LATE SUNDAY INTO MONDAY...WITH HIGH PRESSURE BUILDING OVER THE LOWER GREAT LAKES MONDAY. THIS HIGH WILL SHIFT INTO THE EASTERN GREAT LAKES ON WEDNESDAY. WINDS THROUGH THE WEEKEND WILL BE NO HIGHER THAN 20 KNOTS. THE NEXT CHANCE FOR STRONGER WINDS WILL BE ON MONDAY. NORTHWEST WINDS THEN ARE LIKELY TO REACH 25 KNOTS... ESPECIALLY OVER THE EAST HALF...AS HIGH PRESSURE FOLLOWS THE TROUGH INTO THE UPPER GREAT LAKES. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/SHORT TERM...KC LONG TERM...KF AVIATION...KC MARINE...KC mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DULUTH MN 513 PM CDT FRI SEP 5 2008 .UPDATE... INCREASED POPS ACROSS THE AREA...MENTIONING PRECIPITATION EVERYWHERE AND INTRODUCING ISOLATED THUNDER...AT LEAST THIS EVENING. && .DISCUSSION... LOW PRESSURE OVER THE UPPER SAINT CROIX VALLEY WITH AN ACTIVE WARM FRONT ALONG THE INLAND COUNTIES OF NORTHWEST WISCONSIN AND A STRENGTHENING TROUGH AND COLD FRONT FROM THE CASS LAKES AREA EASTWARD TO JUST BELOW DULUTH AND SOUTHWARD ALONG THE SAINT CROIX RIVER HAS STIMULATED SMALLISH...SHALLOW BUT POTENT AND LONG LIVED SHOWERS DROPPING HALF AN INCH OF RAIN PER HOUR ACROSS AT LEAST A DOZEN AREAS. WE DO NOT SEE LIGHTNING ATTM...BUT MIGHT SOON. FALLING HEIGHTS AND COOLING ALOFT FASTER THAN AT THE SURFACE AS A DIGGING AND NEGATIVE-TILTED SHORT WAVE DROPS DOWN TO SUPPORT THIS SLOWLY BUT STEADILY DEEPEENING NEGATIVELY-ORIENTED SURFACE LOW IS ALSO BEING ACCOMPANIED BY SIGNIFICANT SPEED DIVERGENCE ALOFT OVER THE STRONGEST SHOWER AREAS. WE ARE STARTING WITH A RADICAL MOISTENING OF TONIGHT/S FORECAST AND WILL BE LOOKING AT OTHER PARAMETERS IN THE NEXT HOUR OR TWO. && .PREV DISCUSSION... /ISSUED 238 PM CDT FRI SEP 5 2008/ DISCUSSION... SFC LOW NEAR PKD EARLY THIS AFTERNOON WITH ELONGATED SFC TROUGH STRETCHING NORTH TO BDE...AND SOUTH TOWARDS SAZ. MSAS INDICATES A WEAK SECONDARY PRESS FALL CENTER DEVELOPING NEAR RZN. THIS AGREES WELL WITH MDL FCST OF SFC LOW PRESSURE TROUGH ELONGATING SE THIS AFTERNOON. EXTENSIVE CLOUD SHIELD COVERS MOST OF CWA EXCEPT SE WISC WHERE ISENTROPIC ASCENT HAS NOT ARRIVED YET. PRECIP HAS BEEN MINIMAL AS FORCING IS WEAK. LATEST VIS IMAGERY INDICATES INCREASING CONVECTIVE ELEMENTS ENTERING SW CORNER OF CWA. THIS APPEARS TO BE WITHIN A LOW LEVEL THETAE AXIS. 4KM SPC NMM-WRF SIM REFL PRODUCT ACTUALLY DEPICTS THIS CLUSTER AND WORKS IT EAST THIS AFTERNOON TOWARD TWIN PORTS....WEAKENING THE INTENSITY AS IT DOES. A CELL DID PULSE TO 52DBZ AT 11K WITHIN PAST HR NEAR CASS LAKE BUT HAS WEAKENED IN SUBSEQUENT SCANS. LATEST RUC13 SUGGESTS WE NEED 50DBZ CORES TO 16/17K TO GENERATE ANY SIGNIFICANT HAIL. MARGINAL PARAMETERS FOR SIG CONVECTION AS SFC/MUCAPES REMAIN BELOW 1000J/KG...ALTHOUGH 0-6KM SHEAR IS ABOUT 35KTS IN BEST CAPE VICINITY. HAVE LEFT ISO TRW IN FCST THROUGH THIS AFTERNOON BUT NO LIGHTNING HAS BEEN INDICATED WITH ACTIVITY SO FAR. TONIGHT...ELONGATED SFC PRESS TROUGH WILL STRETCH FROM NORTHERN ITASCA TO SAWYER COUNTIES EARLY THIS EVENING. THIS FEATURE WILL CRAWL NORTHEAST OVERNIGHT WITH WEAK CONVERGENCE EXPECTED. PWS RIBBON ASSOCIATED WITH THIS SYSTEM IS NOT THAT IMPRESSIVE SO QPF REMAINS FAIRLY LIGHT. WILL NEED TO ASSESS FOG/BR POTENTIAL BEFORE ZONE ISSUANCE AS POOLING OF MOISTURE NEAR SFC BDRY...COMBINED WITH LIGHT WINDS...MAY PROMOTE LOW VISIBILITIES. TOMORROW...LEANING WITH SREF SCENARIO WITH SUPPORT FROM EC/GFS. THIS KEEPS POPS CONCENTRATED OVER NRN THIRD OF CWA WHERE DEEPER LAYER MOISTURE AND SOME WEAK CONVERGENCE WILL BE PROVIDED BY SFC BDRY. CLOUD FCST WILL BE CHALLENGING AS BREAKS ARE LIKELY PERIODICALLY IN MANY AREAS...ESPECIALLY BY AFTERNOON OVER SRN HALF OF CWA. EXTENDED...A BRIEF LULL SATURDAY EVENING BEFORE NEXT MID LVL DISTURBANCE SWEEPS INTO REGION SUNDAY MORNING.85H TEMPS DROP WITH PASSAGE OF UPPER TROF SO TEMPS WILL COOL SUNDAY/MONDAY/TUES. SLOW MODERATION THEREAFTER ALTHOUGH INCREASING CLOUDS MAY OFFSET ANY WARM ADVECTION ON WEDNESDAY. AVIATION... IFR AND MVFR CONDITIONS HAVE GIVEN WAY TO PREDOMINATELY VFR CONDITIONS ACROSS THE TERMINALS. SCATTERED 15K-25K CLOUDS CAN BE FOUND...WITH A BROKEN TO OVERCAST DECK AT 5K-7K FEET. THERE ARE A FEW POCKETS OF MVFR/IFR IN THE LONGVILLE...TO GRAND RAPIDS...TO BIGFORK AREA...AND OUT TOWARDS BEMIDJI AS OF 20Z. VFR CONDITIONS WILL BE FOUND THROUGH THE REMAINDER OF THE AFTERNOON...WITH OCCASIONAL MVFR CEILINGS GENERALLY AROUND 15K FEET IN RAIN SHOWERS...AS AN UPPER LEVEL DISTURBANCE MOVES EAST THROUGH THE NORTHLAND. CONVECTIVE PARAMETERS ARE WEAK...AND SO HAVE LEFT THE MENTION OF THUNDER OUT...THOUGH THUNDER IS NOT OUT OF THE QUESTION. LOW LEVEL MOISTURE IS EXPECTED TO LINGER INTO THE OVERNIGHT HOURS...PARTICULARLY IN THE NORTH...FROM KINL TO KHIB TO KDLH. HAVE MENTIONED SOME MVFR/IFR STRATUS...WITH SOME FOG AND IFR/LIFR AT KHIB AND KHYR. TOMORROW...COLD UPPER LEVEL TEMPERATURES WILL LEAD TO CUMULUS DEVELOPMENT...WITH THE CHANCE FOR MORE SHOWERS AND ISOLATED THUNDERSTORMS...THOUGH THESE WILL BE AFTER THE 18Z TIME FRAME. && POINT TEMPS/POPS... DLH 47 70 47 60 / 40 20 10 50 INL 46 66 40 60 / 30 30 40 40 BRD 45 70 46 61 / 20 10 40 50 HYR 45 69 43 64 / 40 10 10 50 ASX 48 68 44 65 / 50 20 10 50 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. $$ EOM/TL mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 238 PM CDT FRI SEP 5 2008 .DISCUSSION... SFC LOW NEAR PKD EARLY THIS AFTERNOON WITH ELONGATED SFC TROUGH STRETCHING NORTH TO BDE...AND SOUTH TOWARDS SAZ. MSAS INDICATES A WEAK SECONDARY PRESS FALL CENTER DEVELOPING NEAR RZN. THIS AGREES WELL WITH MDL FCST OF SFC LOW PRESSURE TROUGH ELONGATING SE THIS AFTERNOON. EXTENSIVE CLOUD SHIELD COVERS MOST OF CWA EXCEPT SE WISC WHERE ISENTROPIC ASCENT HAS NOT ARRIVED YET. PRECIP HAS BEEN MINIMAL AS FORCING IS WEAK. LATEST VIS IMAGERY INDICATES INCREASING CONVECTIVE ELEMENTS ENTERING SW CORNER OF CWA. THIS APPEARS TO BE WITHIN A LOW LEVEL THETAE AXIS. 4KM SPC NMM-WRF SIM REFL PRODUCT ACTUALLY DEPICTS THIS CLUSTER AND WORKS IT EAST THIS AFTERNOON TOWARD TWIN PORTS....WEAKENING THE INTENSITY AS IT DOES. A CELL DID PULSE TO 52DBZ AT 11K WITHIN PAST HR NEAR CASS LAKE BUT HAS WEAKENED IN SUBSEQUENT SCANS. LATEST RUC13 SUGGESTS WE NEED 50DBZ CORES TO 16/17K TO GENERATE ANY SIGNIFICANT HAIL. MARGINAL PARAMETERS FOR SIG CONVECTION AS SFC/MUCAPES REMAIN BELOW 1000J/KG...ALTHOUGH 0-6KM SHEAR IS ABOUT 35KTS IN BEST CAPE VICINITY. HAVE LEFT ISO TRW IN FCST THROUGH THIS AFTERNOON BUT NO LIGHTNING HAS BEEN INDICATED WITH ACTIVITY SO FAR. TONIGHT...ELONGATED SFC PRESS TROUGH WILL STRETCH FROM NORTHERN ITASCA TO SAWYER COUNTIES EARLY THIS EVENING. THIS FEATURE WILL CRAWL NORTHEAST OVERNIGHT WITH WEAK CONVERGENCE EXPECTED. PWS RIBBON ASSOCIATED WITH THIS SYSTEM IS NOT THAT IMPRESSIVE SO QPF REMAINS FAIRLY LIGHT. WILL NEED TO ASSESS FOG/BR POTENTIAL BEFORE ZONE ISSUANCE AS POOLING OF MOISTURE NEAR SFC BDRY...COMBINED WITH LIGHT WINDS...MAY PROMOTE LOW VISIBILITIES. TOMORROW...LEANING WITH SREF SCENARIO WITH SUPPORT FROM EC/GFS. THIS KEEPS POPS CONCENTRATED OVER NRN THIRD OF CWA WHERE DEEPER LAYER MOISTURE AND SOME WEAK CONVERGENCE WILL BE PROVIDED BY SFC BDRY. CLOUD FCST WILL BE CHALLENGING AS BREAKS ARE LIKELY PERIODICALLY IN MANY AREAS...ESPECIALLY BY AFTERNOON OVER SRN HALF OF CWA. EXTENDED...A BRIEF LULL SATURDAY EVENING BEFORE NEXT MID LVL DISTURBANCE SWEEPS INTO REGION SUNDAY MORNING.85H TEMPS DROP WITH PASSAGE OF UPPER TROF SO TEMPS WILL COOL SUNDAY/MONDAY/TUES. SLOW MODERATION THEREAFTER ALTHOUGH INCREASING CLOUDS MAY OFFSET ANY WARM ADVECTION ON WEDNESDAY. && .AVIATION... IFR AND MVFR CONDITIONS HAVE GIVEN WAY TO PREDOMINATELY VFR CONDITIONS ACROSS THE TERMINALS. SCATTERED 15K-25K CLOUDS CAN BE FOUND...WITH A BROKEN TO OVERCAST DECK AT 5K-7K FEET. THERE ARE A FEW POCKETS OF MVFR/IFR IN THE LONGVILLE...TO GRAND RAPIDS...TO BIGFORK AREA...AND OUT TOWARDS BEMIDJI AS OF 20Z. VFR CONDITIONS WILL BE FOUND THROUGH THE REMAINDER OF THE AFTERNOON...WITH OCCASIONAL MVFR CEILINGS GENERALLY AROUND 15K FEET IN RAIN SHOWERS...AS AN UPPER LEVEL DISTURBANCE MOVES EAST THROUGH THE NORTHLAND. CONVECTIVE PARAMETERS ARE WEAK...AND SO HAVE LEFT THE MENTION OF THUNDER OUT...THOUGH THUNDER IS NOT OUT OF THE QUESTION. LOW LEVEL MOISTURE IS EXPECTED TO LINGER INTO THE OVERNIGHT HOURS...PARTICULARLY IN THE NORTH...FROM KINL TO KHIB TO KDLH. HAVE MENTIONED SOME MVFR/IFR STRATUS...WITH SOME FOG AND IFR/LIFR AT KHIB AND KHYR. TOMORROW...COLD UPPER LEVEL TEMPERATURES WILL LEAD TO CUMULUS DEVELOPMENT...WITH THE CHANCE FOR MORE SHOWERS AND ISOLATED THUNDERSTORMS...THOUGH THESE WILL BE AFTER THE 18Z TIME FRAME. && POINT TEMPS/POPS... DLH 47 70 47 60 / 20 20 10 50 INL 46 66 40 60 / 20 30 40 40 BRD 45 70 46 61 / 10 10 40 50 HYR 45 69 43 64 / 30 10 10 50 ASX 48 68 44 65 / 30 20 10 50 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. $$ CANNON/GSF/KD mn