AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 245 PM MDT THU SEP 14 2006 .SHORT TERM... (TONIGHT AND FRIDAY) MAIN CONCERNS REMAIN PRECIP CHANCES...WINDS AND TEMPERATURES ACROSS THE REGION WITH PASSING UPPER LEVEL SYSTEM. CURRENT WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSIS INDICATING INCREASING SOUTHWEST FLOW ALOFT AS VIGOROUS SHORT WAVE TROUGH AND ASSOCIATED 80+ KT JET CORE MOVE INTO THE FOUR CORNERS REGION ATTM. WATER VAPOR IMAGERY ALSO INDICATING DRIER AIR ACROSS THE DESERT SW THROUGH THE SOUTHERN HIGH PLAINS FILTERING INTO EXTREME SOUTHERN COLORADO WITH AMPLE ATMOSPHERIC MOISTURE EMBEDDED IN THE FLOW ACROSS THE GREAT BASIN AND INTERMOUNTAIN WEST ATTM. AT THE SFC...LEE TROUGH DEEPENING ACROSS THE I-25 CORRIDOR WITH DEEP MIXING ACROSS THE THE SE PLAINS KEEPING BREEZY SOUTH TO SOUTHWEST WINDS IN PLACE ATTM. REGIONAL RADARS INDICATING NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS EASTERN UTAH MOVING INTO EXTREME WESTERN COLORADO WITH ISOLATED TO SCATTERED STORMS DEVELOPING ACROSS THE SOUTH CENTRAL COLORADO ATTM. TONIGHT AND FRIDAY...MODERATE SOUTHWEST FLOW ALOFT TO CONTINUE ACROSS THE REGION AS SHORT WAVE AND ASSOCIATED JET MOVE ACROSS SOUTH CENTRAL COLORADO THROUGH THE EVENING AND INTO THE CENTRAL HIGH PLAINS THROUGH THE DAY FRIDAY AS A STRONG PAC NW SYSTEM CONTINUES TO DIVE INTO THE NORTHERN GREAT BASIN. BEST MOISTURE AND LIFT ASSOCIATED WITH THE SYSTEM PROGGED TO REMAIN ACROSS NORTHERN AND WESTERN COLORADO AS DRIER AIR ACROSS THE DESERT SW CONTINUES TO FILTER INTO THE SOUTHERN REACHES OF THE STATE. WITH THAT SAID...HAVE KEPT HIGH SCATTERED TO LIKELY POPS ACROSS THE SW AND CENTRAL MTS THROUGH THE OVERNIGHT...WITH SCATTERED POPS ACROSS THE HIGH MT VALLEYS THROUGH THE EASTERN MTS. HAVE KEPT GENERALLY ISOLATED POPS ACROSS THE I-25 CORRIDOR AND FAR SE PLAINS THROUGH THE EVENING AS WELL. MODELS SOUNDINGS INDICATING CAPES TO BETWEEN 400-800 J/KG AND WITH THE INCREASING FLOW ALOFT...BULK SHEARS ARE INCREASING AS WELL...THOUGH MAINLY UNIDIRECTIONAL SAVE THE I-25 CORRIDOR...WHERE A FEW STORMS COULD PRODUCE MARGINAL HAIL AND GUSTS UP TO 40 MPH. WITH DEEPENING LEE TROUGH AND INCREASING FLOW ALOFT...GRADIENT/GAP WINDS EXPECTED TO STRENGTHEN ACROSS THE LOWER EASTERN SLOPES...ALONG WITH AN EXPECTED MIXED LAYER ACROSS THE FAR EASTERN PLAINS...TO KEEP TEMPERATURES UP ACROSS EASTERN COLORADO AND HAVE GONE AT OR ABOVE GUIDANCE TEMPS OVERNIGHT. WITH CONTINUED MODERATE SW FLOW ACROSS THE AREA AND DRIER AIR ACROSS EASTERN COLORADO...SHOULD SEE BREEZY TO WINDY AND WARM CONDITIONS ONCE AGAIN AS THE PLAINS MIX OUT QUICK TOMORROW MORNING. HAVE KEPT ISOLATED TO SCATTERED POPS IN PLACE ACROSS THE SW AND CENTRAL MTS AND HIGH MT VALLEYS...WITH PROXIMITY TO BEST MOISTURE AND LIFT AHEAD OF PAC NW SYSTEM. -MW .LONG TERM... (SAT THROUGH THU) ...BREEZY TO WINDY CONDITIONS POSSIBLE SAT... ...HIGH TERRAIN MOUNTAIN SNOW CENTRAL MOUNTAINS SAT THROUGH SUN... ...POSSIBLE WIDESPREAD FREEZING CONDITIONS MOUNTAIN VALLEYS SUN... MODEL DISCUSSION...WRF TRENDING TOWARDS A SLOWER SOLUTION...LIKE THE GFS...ON THE WEATHER SYSTEM TO MOVE THROUGH THE NORTHERN AND CENTRAL ROCKIES. WRF AND GFS HAVE TRENDED TOWARDS THE UPPER LEVEL JET STREAM A LITTLE FURTHER NORTH OVER NORTHERN CO FOR SAT. GENERALLY WENT WITH A BLEND OF WRF AND GFS SAT AND STAYED CLOSE TO CURRENT FORECAST BEYOND. SAT...90-120 KT H25 UPPER LEVEL JET STREAK PROGGED TO MOVE ACROSS NORTHERN CO WITH THE ASSOCIATED H5 CLOSED LOW OVER WY/MT. VERY CHALLENGING MINIMUM TEMPERATURE FORECAST AS THE LOWER TROPOSPHERE MAY STAY MIXED DUE TO INCREASING WINDS ALOFT AND LEE SIDE TROUGH/DRYLINE NEAR THE CO/KS BORDER. WILL TWEAK MINIMUM TEMPERATURES A FEW DEGREES...WHICH MIGHT NOT BE ENOUGH. DEEP SOUTHWEST TO WESTERLY FLOW DEVELOPS OVER THE SOUTHERN ROCKIES AND THE AIR MASS IS PRETTY "DRY". H5-H3 RELATIVELY HUMIDITY IS FORECAST TO BE 5-20 PERCENT...WHICH DOESN'T SUPPORT MUCH IN THE WAY OF CLOUDS AND THE LOW LEVEL MOISTURE SHOULD GET WIPED OUT GIVEN THE DEEP MIXING. SURFACE DEW POINTS ARE FORECAST TO DROP CONSIDERABLY SAT AFTERNOON AND EVENING. CONCEPTUALLY AND GIVEN THE LACK OF MOISTURE IN THIS PATTERN...THE POTENTIAL FOR PRECIPITATION IS PRETTY LOW OR NIL...EXCEPT FOR POSSIBLY THE CENTRAL CO MOUNTAINS. WILL LEAVE SOME SMALL POPS/WX IN THIS AREA. THERE COULD BE SOME SNOWFALL ACCUMULATIONS AT THE HIGHER ELEVATIONS OF THE SAWATCH AND MOSQUITO MOUNTAIN RANGES. THE MORE NOTICEABLE SENSIBLE WEATHER SHOULD BE THE WIND. PATTERN WOULD SUGGEST AT LEAST BREEZY TO WINDY CONDITIONS. THE PREVIOUSLY PROJECTED BORA PATTERN IS NOT AS STRONG THIS MODEL RUN...HOWEVER...H5 WINDS ARE FORECAST TO BE 50-70KTS DURING PEAK HEATING AND PRESSURE GRADIENT FORCES SAT AFTERNOON... SO WILL MAINTAIN A BREEZY TO WINDY FORECAST. HAVE WIND GUSTS GOING 20-30KTS ABOVE WIND SPEEDS GENERALLY ABOVE 7K FT MSL. WOULD NOT BE SURPRISED TO SEE SOME 45KT GUSTS IN THE SAN LUIS VALLEY...WALSENBURG AREA...AND OTHER FAVORED "HIGH WIND" CHANNELLING LOCATIONS. MAXIMUM TEMPERATURES WILL BE A CHALLENGE TOO. WITH THE UPPER LEVEL JET STREAM A LITTLE FURTHER NORTH AND ONLY A WEAK COLD FRONT MOVING THROUGH CO...H7 TEMPERATURES JUMP UP TO +10 TO +12C...WHICH WOULD SUPPORT 80S TO NEAR 90F IN SOUTHEASTERN CO. GIVEN THE WIND SPEEDS AND LOWERING HUMIDITY VALUES...WOULD BE A LITTLE CONCERNED ABOUT CRITICAL FIRE WEATHER CONDITIONS AS WE ARE STILL IN MODERATE DROUGHT...BUT IT HAS BEEN SO WET IN THE PAST MONTHS. THE BLM FUEL MOISTURE STATUS WEB PAGE INDICATES FUELS ARE CRITICAL FOR LARGE FIRE GROWTH...SO UNSURE WHAT TO BELIEVE. WILL NEED TO MONITOR FOR CRITICAL FIRE WEATHER CONDITIONS SAT AFTERNOON AND MAY NEED FIRE WEATHER HEADLINES ON SAT. SUN...CHALLENGING FORECASTS THIS DAY. GIVEN MUCH LOWER DEW POINTS...ESPECIALLY IN THE MOUNTAINS AND HIGH VALLEYS...EARLY MORNING LOW TEMPERATURES COULD REACH INTO THE 20S ACROSS THE UPPER AR RIVER...WET MOUNTAIN...AND SAN LUIS VALLEYS. TOUGH CALL. MOS HAS TWEAKED UP TO AROUND 30F AT KALS. JUST DEPENDS IF THE SURFACE WIND CAN DECOUPLE SAT NIGHT/SUN MORNING. GFS TRIES TO DEVELOP ANOTHER LOW OVER THE CENTRAL ROCKIES INCLUDING PRECIPITATION. SINCE THIS IS SUCH A DRASTIC CHANGE...PLAN TO IGNORE. TAIL-END OF THE WRF INDICATES NORTHWESTERLY "DRY" FLOW. MAXIMUM TEMPERATURES SHOULD BE RELATIVELY COOLER ON SUN. MON THROUGH THU...GFS IS ALL OVER THE PLACE WITH CLOSED LOWS MIGRATING EASTWARD THROUGH THE NORTHERN AND CENTRAL ROCKIES. PLAN TO STICK CLOSER TO CLIMATOLOGY...OR SLIGHTLY BELOW. STILL COULD GET RELATIVELY WIDESPREAD FREEZING CONDITIONS ACROSS THE MOUNTAIN HIGH VALLEYS...INCLUDING THE SAN LUIS VALLEY MON AND TUE. LOOKS LIKE WE MAY BE HEADING INTO AN ACTIVE UPPER LEVEL JET STREAM DIRECTLY OVER THE CENTRAL ROCKIES...WHICH WOULD SUPPORT GENERALLY MILD AND BREEZY/WINDY CONDITIONS. METZE && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 23/17 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1001 PM EDT THU SEP 14 2006 .UPDATE... FOG IS ALREADY DEVELOPING ACROSS THE SAGINAW VALLEY AND THUMB UNDER CLEAR SKIES. SURFACE HIGH PRESSURE WILL BE ANCHORED OVER LOWER MICHIGAN THROUGH THE NIGHT. CLEAR SKIES...LIGHT WINDS AND AMPLE MOISTURE IN THE LOWEST 2000 FT NEAR THE SURFACE...SUPPORTED BY THE 00Z DTX SOUNDING...WILL LEAD TO THE DEVELOPMENT OF WIDESPREAD DENSE FOG. THE 00Z DTX SOUNDING DID SHOW A STRONG INVERSION NEAR 5K FT. DESPITE THIS INVERSION...DRY AIR ADVECTION NEAR THIS LEVEL IS ALLOWING THE CLOUDS ACROSS THE SOUTHERN PORTIONS OF THE FORECAST AREA TO DIMINISH RATHER QUICKLY. THERE IS ALSO A LOW STRATUS DECK OVER SOUTHERN LAKE HURON. THE 12KM NAM HAS A REASONABLE HANDLE ON THIS STRATUS DECK AND ESSENTIALLY SUGGESTS THE CLOUDS WILL NOT MAKE MUCH ADDITIONAL PROGRESS WEST INTO THE FORECAST AREA. THEREFORE A DENSE FOG ADVISORY HAS BEEN ISSUED FOR THE ENTIRE FORECAST AREA THROUGH 10 AM FRI MORNING. THE URBAN HEAT ISLAND AFFECT AND A LITTLE STRONGER WINDS FORECAST ATOP THE NOCTURNAL INVERSION MAY LIMIT THE DURATION OF THE DENSE FOG WITHIN THE CITY OF DETROIT AND INNER SUBURBS TO A BRIEF PERIOD AROUND SUNRISE. && .PREV DISCUSSION...ISSUED 715 PM EDT THU SEP 14 2006 .AVIATION... REDUCED VISIBILITIES IN FOG WILL BE A BIG AVIATION CONCERN TONIGHT AND FRIDAY MORNING. HIGH PRESSURE WILL CENTER ITSELF OVER THE STATE TONIGHT. SATELLITE DATA EARLY THIS EVENING HAS BEEN SHOWING A CLEARING TREND AT ALL THE TAF SITES. CLEAR SKIES...LIGHT WINDS AND HIGH SOIL MOISTURE WILL SET THE STAGE FOR OPTIMAL RADIATIONAL FOG DEVELOPMENT TONIGHT. RECENT TAMDAR SOUNDINGS OUT OF DTW INDICATE MOISTURE SLIGHTLY INCREASING WITH HEIGHT IN THE LOWEST COUPLE HUNDRED FEET OF THE SOUNDING AND WITH CROSSOVER TEMPS IN THE MID 50S...SEVERAL DEGREES ABOVE EXPECTED MIN TEMPS...DENSE FOG WILL BE LIKELY LATE TONIGHT THROUGH EARLY FRI MORNING. WILL CARRY SEVERAL HOURS OF QUARTER MILE VISIBILITY AT FNT AND MBS. THE COMBINATION OF THE URBAN HEAT ISLAND AFFECT AND A LITTLE STRONGER NORTHERLY WINDS JUST ATOP THE NOCTURNAL INVERSION MAY BE ENOUGH TO PREVENT DENSE FOG AT DTW AND DET. ALSO HAVE SOME CONCERN THAT LOW STRATUS DECK OVER SOUTHERN LAKE HURON MAY BUILD INTO THE DETROIT AREA LATE TONIGHT. WILL THUS KEEP VISIBILITIES JUST ABOVE A HALF A MILE IN THE DETROIT TAFS AND CONTINUE TO MONITOR THE DENSE FOG POTENTIAL THROUGH THE NIGHT. BASED ON OBS IN WISCONSIN YESTERDAY AND GIVEN THE LOWER MID SEPTEMBER SUN ANGLE...FOG SHOULD NOT MIX OUT UNTIL 13-15Z. PREV DISCUSSION...ISSUED 344 PM EDT THU SEP 14 2006 SHORT TERM...TONIGHT AND FRIDAY 12Z RAOBS/WATER VAPOR LOOP SHOW THE UPPER LOW DOWNSTREAM OVER THE LOWER GREAT LAKES...WITH A RIDGE BUILDING IN ACROSS THE CENTRAL CONUS. SURFACE ANALYSIS SHOWS HIGH PRESSURE ALONG THE MISSISSIPPI VALLEY TO THE CENTRAL GREAT LAKES. VIS SATELLITE SHOWS A HEALTHY MVFR/VFR CLOUD FIELD...BEGINNING TO MIX OUT ACROSS NORTHERN LOWER AND THE THUMB BUT HOLDING FAST ACROSS THE WESTERN AND SOUTHERN CWA. 18Z/19Z TAMDAR SOUNDINGS SHOW A DECENT AMOUNT OF LOW-LEVEL MOISTURE ACROSS NORTHERN LOWER...MORE THAN 15Z RUC/12Z NAM WOULD INDICATE. CLOUDS ACROSS THE THUMB HAVE MIXED INTO A DIURNAL CU DECK WHICH WILL DISSIPATE BEFORE SUNSET...WHILE THE THICKER STRATOCU DECK ACROSS THE THE SOUTHERN AND WESTERN CWA MAY LINGER LONGER INTO THE EVENING. STILL EXPECT SKIES TO CLEAR OUT OVERNIGHT...BUT WILL INCREASE CLOUD COVER THROUGH THE EVENING. THIS MAY HAVE SOME IMPACT ON DENSE FOG POTENTIAL TONIGHT. SURFACE RIDGE WILL BUILD ACROSS LOWER MICHIGAN BY 12Z FRIDAY...WITH NEARLY CALM WINDS ACROSS THE CWA. NAM/GFS BOTH SHOW GOOD LOW-LEVEL MOISTURE...INCLUDING SURFACE CONDENSATION PRESSURE DEFICITS BELOW 10MB. THERE WAS PRETTY WIDESPREAD FOG WITH VISIBILITIES 1/4SM OR BELOW UNDER THE RIDGE AXIS UPSTREAM ACROSS WISCONSIN THIS MORNING...AS WELL AS SOME FOG REPORTS ACROSS NORTHERN ONTARIO WHERE OUR AIRMASS WILL ORIGINATE ON DIMINISHING NORTHERLY WINDS. WILL ADD AREAS OF DENSE FOG TO THE FORECAST OVERNIGHT INTO FRIDAY MORNING. WAS ON THE FENCE ABOUT A DENSE FOG ADVISORY AT THIS POINT...AND DECIDED TO HOLD OFF GIVEN UNCERTAINTY AS TO HOW QUICKLY CLOUDS WILL CLEAR OUT THIS EVENING...AS WELL AS HOW LOWER DEWPOINTS WILL MIX DOWN ACROSS NORTHERN LOWER AS THE NORTHERN CLOUDS DISSIPATE. LOWS IN THE UPPER 40S LOOK GOOD...WITH LOWER 50S ACROSS THE SOUTHERN CWA WITH THE MORE PERSISTENT CLOUD COVER. UPPER RIDGE AXIS BUILDS ACROSS LOWER MICHIGAN ON FRIDAY...WITH THE SURFACE HIGH SHIFTING DOWNSTREAM TO SOUTHEAST ONTARIO. RETURN FLOW WILL REMAIN PRETTY WEAK BEHIND THE HIGH...AT LEAST THROUGH THE DAY. EVEN WITH FULL SUN...GFS LOOKS TOO WARM WITH REMNANT THERMAL TROUGH LINGERING OVER THE REGION. WILL DROP HIGH TEMPERATURES A FEW DEGREES...GENERALLY INTO THE MID 70S FOR FRIDAY. 19Z READINGS THIS AFTERNOON ACROSS WISCONSIN WERE ONLY AROUND 70 TO THE LOW 70S. LONG TERM...FRIDAY NIGHT THROUGH THURSDAY WILL MAINTAIN THE CURRENT FORECAST FOR THE MOST PART AS MODELS STILL SUGGEST A WARMUP THROUGH SUNDAY AS UPPER RIDGE AMPLIFIES TO THE EAST OF A DEVELOPING TROUGH OVER THE PACIFIC NORTHWEST & NORTHERN PLAINS. WILL ALSO KEEP THE DRY FORECAST THROUGH SUNDAY IN THIS PATTERN. AS UPPER LOW SPINS UP OVER THE NORTHERN PLAINS WITH THIS TROUGH ON SUNDAY/SUNDAY NIGHT...MODELS STILL SUGGEST AN OCCLUDED COLD FRONT WILL SHIFT INTO LOWER MICHIGAN LATE SUNDAY NIGHT AND PROGRESS TO THE EAST OF THE AREA BY MIDDAY MONDAY. THIS SUPPORTS THE 40% CHANCE OF SHOWERS/THUNDERSTORMS SUNDAY NIGHT INTO MONDAY. THEREAFTER...SHOWERY WEATHER BECOMES ESTABLISHED IN COLD WEST FLOW OVER THE RELATIVELY WARM WATERS OF LAKE MICHIGAN. WILL BRING THESE SHOWERS INTO THE FORECAST MONDAY NIGHT AND SLOWLY TAPER THEM BACK BY WEDNESDAY NIGHT...BASICALLY TRIMMING AWAY THE SOUTHERN EXTENT DURING THE TIMEFRAME. TEMPERATURES WILL BE DECIDEDLY COOLER NEXT WEEK...AS COMPARED TO THE WEEKEND. MONDAY WILL BE THE TRANSITION DAY AS THE FRONT PROGRESSES THROUGH THE AREA. EXPECT HIGHS IN THE LOWER 70S. HIGHS WILL BE IN THE LOWER 60S TUESDAY/WEDNESDAY IN THE CORE OF THIS COMING COOL AIR WITH A SLIGHT MODIFICATION BY THURSDAY. LOWS WILL HOLD PRETTY MUCH IN THE 40S THROUGH THIS TIMEFRAME AS CLOUDS AND A STEADY WEST WIND ACT TO MODERATE THE NIGHTTIME COOLING. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...DENSE FOG ADVISORY...ALL SOUTHEAST MICHIGAN...MIDNIGHT UNTIL 10 AM. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...BRAVENDER LONG TERM....DG AVIATION/UPDATE...CONSIDINE 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 950 PM EDT THU SEP 14 2006 .UPDATE... FEW CHGS NECESSARY TO GOING FCST. MADE A FEW ADJUSTMENTS TO TEMPS BASED ON CURRENT REPORTS AND EXPANDED AREA OF FCST PTCHY FOG INTO THE INTERIOR WCNTRL WHERE FCST LO TEMPS ARE BLO CROSSOVER TEMPS IN THE UPR 40S. ALSO...DRY WEDGE APRNT ON WV IMAGERY APRCHG FM THE SW SHOULD ALLOW EFFICIENT RADIATIONAL COOLING FOR AT LEAST THE NEXT COUPLE OF HRS. BUT RUC FCST INCRSG SW FLOW OVERNGT IN SHARPENING PRES GRADIENT BTWN HI CENTERED OVER THE CNTRL LKS/LO PRES IN THE PLAINS SHOULD PREVENT TEMPS FM FALLING TOO QUICKLY/FOG FM GETTING TOO WDSPRD/DENSE. KC .PREVIOUS DISCUSSION (ISSUED AT 443 PM EDT)... MAIN FCST CONCERN TODAY WAS THE TIMING OF PCPN FROM THE APPROACHING LOW PRESSURE SYSTEM. WV IMAGERY AND RUC ANALYSIS SHOW A STRENGTHENING HIGH-AMPLITUDE RIDGE OVER THE CENTRAL US. A TROUGH OUT WEST HAS CLOSED AND DEEPENED AND THE CLOSED LOW OUT EAST HAS WEAKENED. DRY AIR AND SUBSIDENCE ARE APPARENT IN MPX/GRB 12Z SNDGS. HENCE THE SUNNY SKIES AND BEAUTIFUL WEATHER. SOME SMOKE HAS BEEN OBSERVED OUTSIDE...ADVECTED IN FROM WILDFIRES IN ONTARIO AND THE WESTERN STATES. KEPT PATCHY FOG EAST DUE TO THE LIGHT WINDS...CLEAR SKIES...SURFACE DEWPOINTS RIGHT NOW IN THE LOW TO MID 50S AND DRY AIR AND SUBSIDENCE ALOFT. WINDS WILL BE PICKING UP ACROSS THE WEST HALF WHICH SHOULD KEEP TEMPERATURES UP AND PREVENT FOG FROM FORMING. THE NAM HAS MOISTURE FROM NE ILLINOIS ADVECTING INTO OUR CWA WITH SOUTHERLY WINDS...AND WITH HIGH TEMPS EXPECTED IN THE UPPER 70S TOMORROW...INCREASED CLOUDS INLAND FOR CU DEVELOPMENT. A SHORTWAVE OVER THE NORTHERN PLAINS IS KICKING UP A SFC LOW OVER THE WESTERN DAKOTAS. THIS LOW IS PROGGED TO SLOWLY STRENGTHEN AND TRACK ACROSS THE MN/MANITOBA/ONTARIO BORDER...AND THEN ACROSS NORTHERN LAKE SUPERIOR AROUND 00Z MON. WITH THE APPROACHING LOW PRESSURE SYSTEM OVER THE WESTERN DAKOTAS...EXPECT INCREASING CLOUD COVER SATURDAY AFTERNOON ASSOCIATED WITH A SHORTWAVE AHEAD OF THE UPPER LOW. STRONG SOUTHERLY WINDS WILL GIVE TEMPS IN THE UPPER 70S/LOWER 80S SAT AND ONLY DOWN TO THE 60S SAT NIGHT. GFS PUTS PCPN ACROSS OUR CWA SAT AND SAT NIGHT SPREADING FROM WEST TO EAST...AND CONCENTRATED PRIMARILY NORTH...ASSOCIATED WITH THIS SHORTWAVE. MUCH HIGHER PRECIPITABLE WATER VALUES COMPARED TO THE CURRENT TIME ALSO SUPPORT THE POSSIBILITY FOR SOME PCPN. THE FRONT IS PROGGED TO PASS THROUGH OUR CWA SUNDAY AFTERNOON. THERE IS A QUESTION ABOUT WHEN OR HOW MUCH THE DRY SLOT WILL AFFECT OUR CWA. KEPT POPS A CHANCE DURING FROPA DUE TO THIS UNCERTAINTY. WILL NEED TO MONITOR FUTURE RUNS TO PINPOINT WHETHER OR NOT THERE WILL BE PCPN AHEAD OF THE FRONT...IF THE DRY SLOT WILL ACTUALLY PAN OUT...AND WHEN TO END CONVECTION AFTER THE FROPA. THE 06Z GFS/00Z ECMWF MODELS GENERALLY AGREE ON THE TRACK OF THE SFC AND UPPER LEVEL LOWS THROUGH ABOUT 12Z MON BEFORE THEY START TO DIVERGE. THE ECMWF KEEPS A LONGWAVE TROF FROM ONTARIO-TX...AND THE GFS HAS A MORE AMPLIFIED PATTERN WITH A CLOSED LOW OVER ONTARIO WITH A TROF THROUGH TX AND A RIDGE FROM SASKATCHEWAN THROUGH THE SOUTHWESTERN US. THE 06Z GFS PUTS OUR CWA UNDER SFC HIGH PRES AT 00Z WED WITH ANOTHER LOW APPROACHING BY 00Z THU. THE ECMWF KEEPS OUR CWA IN A NW WIND FLOW PATTERN (HIGH PRES TO WEST) THROUGH 12Z WED BEFORE HIGH PRESSURE BEGINS TO SETTLE IN. BOTH MODELS AGREE THERE WILL BE ANOTHER LOW PRESSURE SYSTEM DEVELOPING ACROSS THE PLAINS NEXT THU BUT THERE IS STILL CONSIDERABLE DISAGREEMENT ON THE TIMING. WENT WITH A COMPROMISE BETWEEN THE TWO MODELS AND EXPECT SLOWER TIMING OF THE PROGRESSION OF THE NEXT LOW PRESSURE SYSTEM THAN THE GFS. ENDED CHANCE OF PCPN BY WED AFTERNOON...THINKING THAT THE ECMWF CLOSED 500MB LOW MIGHT LINGER A LITTLE WHILE LONGER OVER EASTERN CANADA AND THE NEXT SFC LOW PRESSURE SYSTEM WILL BE SLOWER TO ENTER OUR REGION. THE 12Z GFS/12Z ECMWF ARE IN BETTER AGREEMENT THROUGH 12Z TUE. BY 12Z WED THE GFS STILL KEEPS A HIGH AMPLITUDE PATTERN WITH A RIDGE STRETCHING ALL THE WAY UP INTO NORTHERN SASKATCHEWAN AND TROUGHS ON EITHER SIDE...WHILE THE ECMWF KEEPS THE CLOSED LOW OVER EASTERN CANADA...A WEAK RIDGE OVER THE CENTRAL US...AND ANOTHER CLOSED LOW OVER MT/WY BORDER. GOING FCST OF PREV MODEL COMPROMISE SEEMS OK FOR NOW. WILL NEED TO KEEP AN EYE ON FUTURE SOLNS. MRE && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 443 PM EDT THU SEP 14 2006 .DISCUSSION... MAIN FCST CONCERN TODAY WAS THE TIMING OF PCPN FROM THE APPROACHING LOW PRESSURE SYSTEM. WV IMAGERY AND RUC ANALYSIS SHOW A STRENGTHENING HIGH-AMPLITUDE RIDGE OVER THE CENTRAL US. A TROUGH OUT WEST HAS CLOSED AND DEEPENED AND THE CLOSED LOW OUT EAST HAS WEAKENED. DRY AIR AND SUBSIDENCE ARE APPARENT IN MPX/GRB 12Z SNDGS. HENCE THE SUNNY SKIES AND BEAUTIFUL WEATHER. SOME SMOKE HAS BEEN OBSERVED OUTSIDE...ADVECTED IN FROM WILDFIRES IN ONTARIO AND THE WESTERN STATES. KEPT PATCHY FOG EAST DUE TO THE LIGHT WINDS...CLEAR SKIES...SURFACE DEWPOINTS RIGHT NOW IN THE LOW TO MID 50S AND DRY AIR AND SUBSIDENCE ALOFT. WINDS WILL BE PICKING UP ACROSS THE WEST HALF WHICH SHOULD KEEP TEMPERATURES UP AND PREVENT FOG FROM FORMING. THE NAM HAS MOISTURE FROM NE ILLINOIS ADVECTING INTO OUR CWA WITH SOUTHERLY WINDS...AND WITH HIGH TEMPS EXPECTED IN THE UPPER 70S TOMORROW...INCREASED CLOUDS INLAND FOR CU DEVELOPMENT. A SHORTWAVE OVER THE NORTHERN PLAINS IS KICKING UP A SFC LOW OVER THE WESTERN DAKOTAS. THIS LOW IS PROGGED TO SLOWLY STRENGTHEN AND TRACK ACROSS THE MN/MANITOBA/ONTARIO BORDER...AND THEN ACROSS NORTHERN LAKE SUPERIOR AROUND 00Z MON. WITH THE APPROACHING LOW PRESSURE SYSTEM OVER THE WESTERN DAKOTAS...EXPECT INCREASING CLOUD COVER SATURDAY AFTERNOON ASSOCIATED WITH A SHORTWAVE AHEAD OF THE UPPER LOW. STRONG SOUTHERLY WINDS WILL GIVE TEMPS IN THE UPPER 70S/LOWER 80S SAT AND ONLY DOWN TO THE 60S SAT NIGHT. GFS PUTS PCPN ACROSS OUR CWA SAT AND SAT NIGHT SPREADING FROM WEST TO EAST...AND CONCENTRATED PRIMARILY NORTH...ASSOCIATED WITH THIS SHORTWAVE. MUCH HIGHER PRECIPITABLE WATER VALUES COMPARED TO THE CURRENT TIME ALSO SUPPORT THE POSSIBILITY FOR SOME PCPN. THE FRONT IS PROGGED TO PASS THROUGH OUR CWA SUNDAY AFTERNOON. THERE IS A QUESTION ABOUT WHEN OR HOW MUCH THE DRY SLOT WILL AFFECT OUR CWA. KEPT POPS A CHANCE DURING FROPA DUE TO THIS UNCERTAINTY. WILL NEED TO MONITOR FUTURE RUNS TO PINPOINT WHETHER OR NOT THERE WILL BE PCPN AHEAD OF THE FRONT...IF THE DRY SLOT WILL ACTUALLY PAN OUT...AND WHEN TO END CONVECTION AFTER THE FROPA. THE 06Z GFS/00Z ECMWF MODELS GENERALLY AGREE ON THE TRACK OF THE SFC AND UPPER LEVEL LOWS THROUGH ABOUT 12Z MON BEFORE THEY START TO DIVERGE. THE ECMWF KEEPS A LONGWAVE TROF FROM ONTARIO-TX...AND THE GFS HAS A MORE AMPLIFIED PATTERN WITH A CLOSED LOW OVER ONTARIO WITH A TROF THROUGH TX AND A RIDGE FROM SASKATCHEWAN THROUGH THE SOUTHWESTERN US. THE 06Z GFS PUTS OUR CWA UNDER SFC HIGH PRES AT 00Z WED WITH ANOTHER LOW APPROACHING BY 00Z THU. THE ECMWF KEEPS OUR CWA IN A NW WIND FLOW PATTERN (HIGH PRES TO WEST) THROUGH 12Z WED BEFORE HIGH PRESSURE BEGINS TO SETTLE IN. BOTH MODELS AGREE THERE WILL BE ANOTHER LOW PRESSURE SYSTEM DEVELOPING ACROSS THE PLAINS NEXT THU BUT THERE IS STILL CONSIDERABLE DISAGREEMENT ON THE TIMING. WENT WITH A COMPROMISE BETWEEN THE TWO MODELS AND EXPECT SLOWER TIMING OF THE PROGRESSION OF THE NEXT LOW PRESSURE SYSTEM THAN THE GFS. ENDED CHANCE OF PCPN BY WED AFTERNOON...THINKING THAT THE ECMWF CLOSED 500MB LOW MIGHT LINGER A LITTLE WHILE LONGER OVER EASTERN CANADA AND THE NEXT SFC LOW PRESSURE SYSTEM WILL BE SLOWER TO ENTER OUR REGION. THE 12Z GFS/12Z ECMWF ARE IN BETTER AGREEMENT THROUGH 12Z TUE. BY 12Z WED THE GFS STILL KEEPS A HIGH AMPLITUDE PATTERN WITH A RIDGE STRETCHING ALL THE WAY UP INTO NORTHERN SASKATCHEWAN AND TROUGHS ON EITHER SIDE...WHILE THE ECMWF KEEPS THE CLOSED LOW OVER EASTERN CANADA...A WEAK RIDGE OVER THE CENTRAL US...AND ANOTHER CLOSED LOW OVER MT/WY BORDER. GOING FCST OF PREV MODEL COMPROMISE SEEMS OK FOR NOW. WILL NEED TO KEEP AN EYE ON FUTURE SOLNS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ MRE mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1035 AM EDT THU SEP 14 2006 .UPDATE...MID MORNING SFC ANALYSIS SHOWING RIDGE AXIS EXTENDING FROM EASTERN ONTARIO SOUTHWARD THROUGH THE EASTERN U.P. AND INTO IL. VIS IMAGERY SHOWING MAINLY CLEAR SKIES OVER MUCH OF THE AREA WITH THE EXCEPTION OF EASTERN AREAS...LUCE CO EASTWARD...WHERE MORNING FOG CONTINUES TO SLOWLY BURN OFF. AS SFC RIDGE MOVES EAST TODAY BROAD WARM ADVECTION PATTERN WILL BEGIN TO AFFECT THE AREA AHEAD OF DIGGING UPPER TROF OVER THE NORTHWESTERN U.S. CURRENT TEMPS ARE GENERALLY RUNNING IN THE MID 50S TO AROUND 60 AND WITH ABUNDANT SUNSHINE EXPECTED TODAY COMBINED WITH WEAK WARM ADVECTION AFTERNOON TEMPS SHOULD TOP OUT NEAR PROJECTED MAXES IN THE 70S. WILL NOT MAKE ANY SIGNIFICANT CHANGES TO ONGOING FCST...BUT WILL UPDATE ZFP TO REMOVE MORNING FOG WORDING. .PREVIOUS DISCUSSION (ISSUED AT 414 AM EDT THU SEP 14 2006)...WITH WARM...DRY WEATHER THE NEXT FEW DAYS...FCST CONCERNS ARE MINOR. DOWN THE ROAD...TIMING PROGRESSION OF DEEP WRN TROF AND ITS ASSOCIATED WEATHER INTO THE CNTRL CONUS AND GREAT LAKES LATE WEEKEND INTO EARLY NEXT WEEK WILL BE AN ISSUE. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW PRONOUNCED TROF AMPLIFICATION BEGINNING OVER SW CANADA INTO THE WRN CONUS DOWNSTREAM OF A RIDGE BUILDING THRU ALASKA. 00Z RAOBS SHOWED 12HR 500MB HEIGHT RISES OF 100M IN NW CANADA WHILE HEIGHT FALLS UPWARDS OF 140M WERE NOTED OVER THE PACIFIC NW. AMPLIFYING WRN TROF WILL LEAD TO BUILDING OF THE CURRENTLY LOW AMPLITUDE RIDGE OVER THE CNTRL CONUS. AT THE SFC...HIGH PRES RIDGE EXTENDS FROM LAKE SUPERIOR ACROSS UPPER MI AND WI. IR AND 11-3.9MICRON SATELLITE IMAGERY SHOW CLEAR SKIES OVER THE UPPER LAKES. A SMALL PATCH OF DENSE CI WAS MOVING E ACROSS CNTRL MN WHILE SHIELD OF CLOUDS OVER SRN SASKATCHEWAN/SRN MANITOBA/NW ONTARIO IS GENERALLY HEADING ENE. 11-3.9MICRON IMAGERY ALSO INDICATES WIDESPREAD FOG HAS DEVELOPED OVER THE ERN FCST AREA...GENERALLY E OF A MUNISING TO MANISTIQUE LINE. FOG IS PATCHY ELSEWHERE ACROSS FCST AREA...BUT IT APPEARS FOG IS EXPANDING OVER FAR SCNTRL UPPER PER LATEST SATELLITE IMAGE. AS MENTIONED...AMPLIFYING WRN TROF WILL LEAD TO DOWNSTREAM RIDGE BUILDING OVER THE CNTRL CONUS. MODELS SHOW THIS RIDGE MOVING TO THE WRN GREAT LAKES REGION BY FRI MORNING AND TO THE CNTRL LAKES BY SAT MORNING. MEANWHILE...ASSOCIATED SFC HIGH PRES RIDGE CURRENTLY EXTENDING ACROSS UPPER MI WILL MOVE THE EASTERN GREAT LAKES BY SAT MORNING. END RESULT WILL BE A PERIOD OF WARM MID SEPT WEATHER UNDER PERSISTENT SRLY LOW-LEVEL FLOW. RH TIME SECTIONS CONTINUE TO SHOW PLENTY OF DRY AIR DOMINATING THE AREA THRU FRI NIGHT...SUPPORTING MOSTLY CLEAR SKIES. HOWEVER...THERE IS ONE EXCEPTION. NAM CONTINUES TO SUGGEST THE POSSIBILITY OF SOME LOW CLOUDS DEVELOPING TONIGHT AND AGAIN FRI NIGHT. TO A MUCH LESSER DEGREE...GFS HINTS AT THIS AS WELL. THIS LOW-LEVEL MOISTURE IS TIED TO THE DEPARTING AREA OF MOISTURE ASSOCIATED WITH SYSTEM CURRENTLY MOVING THRU THE UPPER OHIO VALLEY. NAM SHOWS RETURN FLOW BRINGING SOME OF THIS MOISTURE N INTO THE UPPER LAKES. SEEMS LIKE AN UNLIKELY SCENARIO AS DAYTIME HEATING WILL WORK TO MIX OUT LOW-LEVEL MOISTURE THAT MAY BEGIN TO SLIP BACK TO THE N OR NW TODAY AND FRI. SOMETHING THAT WILL NEED TO BE LOOKED AT MORE CLOSELY IS THE POSSIBILITY OF STRATUS/FOG DEVELOPING DOWNWIND OF LAKE MICHIGAN OVER THE ERN FCST AREA. WITH TEMPS DROPPING INTO THE 40S OVER THE E TONIGHT...SRLY FLOW JUST OFF THE SFC AND RESULTING MOISTURE ADVECTION OFF LAKE MICHIGAN OVER THE COOL SFC LAYER MIGHT LEAD TO STRATUS/FOG FORMING. FOR NOW...WILL INCLUDE A MENTION OF PATCHY FOG OVER THE ERN FCST AREA OVERNIGHT. FOG COULD BECOME LOCALLY DENSE. THERE MIGHT BE SOME FOG OVER THE CNTRL FCST AREA...BUT NOT EXPECTING IT TO LIMIT VSBY MUCH (3-5SM)...AND WILL LEAVE OUT OF FCST. LOOKS LIKE A SIMILAR SETUP FRI NIGHT...BUT WITH A TIGHTER PRES GRADIENT OVER THE AREA...STRONGER WINDS SHOULD PREVENT ANY FOG DEVELOPMENT THAT WOULD SIGNIFICANTLY REDUCE VSBY. AS FOR TEMPS...GOING FCST LOOKS ON TRACK. MIXING TO AROUND 825MB ON NAM/GFS FCST SOUNDINGS YIELDS HIGH TEMPS IN THE MID 70S TO NEAR 80 TODAY. THIS IS IN GENERALLY GOOD AGREEMENT WITH GFS MOS GUIDANCE. IT WILL BE COOLER NEAR LAKE MICHIGAN WITH LIGHT SRLY FLOW AND LOCALLY COOLER NEAR LAKE SUPERIOR AS LAKE BREEZES SHOULD KICK IN UNDER WEAK GRADIENT TODAY. GFS COOP GUIDANCE (LOW/MID 40S) IN THE TYPICAL COOL SPOTS LOOKS REASONABLE FOR TONIGHT. WILL BE WARMEST (50S) OVER THE FAR W/NW UNDER STRONGER SRLY FLOW. MIXING TO 825MB YIELDS HIGHS IN THE UPPER 70S/LWR 80S FRI...SIMILAR TO GFS MOS. WILL AGAIN BE COOLER NEAR LAKE MICHIGAN. GRADIENT WILL BE SUFFICIENT TO PREVENT ANY COOLING NEAR LAKE SUPERIOR...EXCEPT E SIDE OF THE KEWEENAW. OVER THE WEEKEND...THERE HAS BEEN A TREND IN THE GFS TO BE FASTER WITH THE EASTWARD PROGRESSION OF THE WRN TROF AND ASSOCIATED SFC LOW/COLD FRONT. 18Z/00Z RUNS SHOW FRONT MOVING INTO WRN UPPER MI EARLY SUN AFTN. THIS IS SIMILAR TO THE 00Z ECMWF. HAVE THUS MADE SOME MINOR ADJUSTMENTS TO SPEED UP FROPA FROM GOING FCST WHICH HAD TIMING ROUGHLY SUN NIGHT/MON MORNING. BEFORE THEN...NAM/GFS/UKMET INDICATE A SHORTWAVE EJECTING OUT OF WRN TROF WHICH MAY JUST BRUSH THE WRN FCST AREA WITH SOME SHRA DURING THE DAY SAT. IF THIS FEATURE IS STILL PRESENT IN NEXT SET OF MODEL RUNS...WILL NEED TO CONSIDER INTRODUCING CHC POPS OVER THE FAR WRN FCST AREA SAT AFTN. OTHERWISE...SPREADING PCPN CHC W TO E SAT NIGHT LOOKS FINE. THERE WILL LIKELY BE A DRY PERIOD BEHIND FROPA AS DRY SLOT SPREADS ACROSS THE AREA...BUT DUE TO TIMING UNCERTAINTY THIS FAR OUT IN FCST...WILL NOT INTRODUCE AT THIS POINT. CHILLY...UNSETTLED WEATHER ON TAP LATER MON/TUE AS DEEP CYCLONIC FLOW SETTLES OVER THE AREA. LAKE EFFECT SHRA WILL CRANK UP UNDER MOIST/CYCLONIC FLOW WITH 850MB TEMPS DOWN BLO 0C. GOING FCST MAX TEMPS TUE MAY BE A BIT OPTIMISTIC. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PREV DISCUSSION...ROLFSON UPDATE...MZ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 940 PM CDT THU SEP 14 2006 .DISCUSSION... GOING FORECAST IN GOOD SHAPE AND WILL JUST UPDATE TO REMOVE EVNING CLD WORDING. TMPS HAVE BEEN FAIRLY SLOW TO FALL OFF THIS EVNG IN THE NW CWA WHERE THE SFC HAS REMAINED COUPLED AND WIND GUSTS CONT. IN CONTRAST THE SE FA HAS FALLEN OFF MORE SIG WITH TMPS ALREADY DOWN IN THE MID 60S. GRADIENT OF GOING LOW FORECAST HAS THIS COVERED WELL AND WILL JUST UPDATE THE HOURLY TMPS FOR A QUICKER FALL IN THE SE. WL CONT TO LEAVE THE FORECAST TONIGHT DRY. 00Z UPPR AIR ANLYS INDCD POTENT SHRTWV TROF OVR CO/KS/TX AHEAD OF THE MAIN UPPR LVL WAVE. MOISTURE AT H85 CONTD TO INCREASE OVR THE SRN PLAINS WITH A +15 C DEWPOINT UP TO CENTRAL TX AND +10 C WELL INTO THE NORTHERN PLAINS. DESPITE THIS INCREASE IN MOISTURE...THE EML IS ALSO INCREASING ACRS THE CNTRL PLAINS THIS EVNG WITH A H7 TMP OF +10 C AT KOAX AT 00Z. THINK MOISTURE WL CONT TO STRM NWD TONIGHT UNDER THE INVERSION...BUT NOT BE AT A DEPTH TO OVERCOME THE INHIBITION UNTIL AFTER 12Z WHEN H85 DEWPOINTS IN THE SRN FA REACH +12 AND +13 C. THUS SCT HIGH-BASED TSRA WL BE POSSIBLE AFTR 12Z FRI. NEW ZFP/GRIDS ALREADY SENT. BOUSTEAD && .PREV DISCUSSION... (ISSUED 315 PM CDT THU SEP 14 2006) FORECAST CHALLENGES CENTER AROUND PCPN CHANCES FRIDAY THROUGH MONDAY. LATEST WATER VAPOR IMAGERY IN COMBINATION WITH RUC 500MB HEIGHT ANALYSIS SHOWS UPPER RIDGE MOVING EAST INTO THE MISSISSIPPI RIVER VALLEY REGION WHILE STRONG UPPER LOW SPINS OVER THE PACIFIC NORTHWEST. 12Z UPPER AIR ANALYSIS SHOWED 170M HEIGHT FALLS AT 500MB OVER OREGON. WEAK SHORTWAVE WAS ALSO EVIDENT ON WATER VAPOR IMAGERY OVER NERN NEW MEXICO AND WILL CONTINUE TO MOVE NORTHEAST INTO ERN CO AND TO WRN NEB BY LATE TONIGHT. AT THE SFC...LOW PRESSURE WAS BUILDING OVER THE WESTERN DAKOTAS WITH FAIRLY STRONG LOW LEVEL SOUTHERLY FLOW AHEAD OF THE LOW. LOW LEVEL MOIST ADVECTION CONTINUES ACROSS THE PLAINS FROM SOUTHWEST TO NORTHEAST THIS AFTERNOON...ESPECIALLY ACROSS THE HIGH PLAINS WHERE SFC DEWPOINTS ARE IN THE LOWER 60S. THIS LOW LEVEL MOISTURE WILL CONTINUE TO INCREASE AND PUSH FURTHER EWD OVERNIGHT. GOOD THETA-E ADVECTION WITH 45KT LOW LEVEL JET SHOULD ADVECT ENOUGH MOISTURE INTO THE REGION BY MORNING TO ALLOW FOR A SLIGHT CHANCE OF TSTMS AFTER SUNRISE. DESPITE SHORTWAVE ENERGY PASSING NEAR THE AREA OVERNIGHT AND SOME ISENTROPIC LIFT...THINK SOUNDINGS ARE WAY TOO DRY TO BRING ANY PCPN TO THE SURFACE OVERNIGHT TONIGHT. LARGE SCALE LIFT INCREASES ACROSS THE AREA ON FRIDAY AFTERNOON AS LEFT FRONT QUAD OF JET STREAK MOVES OVER THE REGION AND ANOTHER WK SHORTWAVE MOVES THRU MID LEVEL FLO. WL CONTINUE SCATTERED TSTM CHANCES THRU THE DAY FRIDAY. LOW LEVEL JET BECOMES MORE SWRLY AND INCREASES TO 50KTS OVERNIGHT FRIDAY AS THE POTENT UPPER STORM SYSTEM PUSHES EAST TOWARDS WYOMING. WILL CONTINUE POPS OVERNIGHT AND INTO SATURDAY AS FORCING FROM EMBEDDED SHORTWAVES MOVES ACROSS OUR AREA. SATURDAY AFTERNOON STILL LOOKS LIKE A DECENT SVR WX SET UP AS INSTABILITY INCREASES AHEAD OF PREFRONTAL TROF. NAM IS SLIGHTLY FASTER ON PUSHING THIS FEATURE THRU THAN THE GFS AND HAVE GONE WITH THE MORE CONSISTENT GFS SOLUTION FOR TIMING THIS FEATURE. SHEAR PROFILES STILL LOOK FAVORABLE FOR SUPERCELLS AND THINK AFTERNOON INITIATION ACROSS THE CWA IS LIKELY. STORMS SHOULD BE QUICK TO MOVE EAST AS PREFRONTAL TROF PUSHES QUICKLY THRU THE ENTIRE FORECAST AREA BY LATE SATURDAY NIGHT. MOST SHOWER ACTIVITY BEHIND THIS FEATURE SHOULD END QUICKLY BY EARLY SUNDAY WITH TRUE COLD FRONT PUSHING INTO THE AREA LATER ON SUNDAY. A FEW SHOWERS ARE NOT OUT OF THE QUESTION LATE SUNDAY INTO MONDAY AS SYSTEM MOVES OVER THE GREAT LAKES AND DRAGS ENERGY INTO THE CENTRAL PLAINS. COLDER AIR WILL BE THE MAIN STORY THRU THE WORK WEEK WITH -2C 850MB ISOTHERM STILL PROGGED TO SLIDE DOWN ON US EARLY TUESDAY. WITH HIGH PRESSURE RIDGE CENTERED OVER THE REGION TUESDAY MORNING...HAVE LOWERED LOWS A COUPLE OF DEGREES SO WE RANGE IN THE UPPER 30S NORTH TO LOWER 40S SOUTH. AS FOR THE EXTENDED PERIODS...FOLLOWED THE 06Z AND 12Z GFS. THIS MOVES ANOTHER UPPER TROF THROUGH THE NRN PLAINS AND RESULTANT SFC LOW INTO THE CENTRAL PLAINS BY MID WEEK. THIS PUTS US IN WARMER SOUTHERLY FLOW TO REBOUND TEMPS INTO THE 70S BY WED. HAVE NOT INCLUDED ANY PCPN FOR THIS PERIOD AS OF YET. GRIFFIS && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ ne AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BINGHAMTON NY 920 AM EDT THU SEP 14 2006 .SHORT TERM /TODAY - FRIDAY NGT/... UPDATE - WATER VAPOR SHOWS THE MID LVL CIRCULATION OVER NW PA. RUC AND LOCAL NAM RUN BRING THE CENTER OF THE CIRCULATION OVER THE CNTRL SRN TIER THIS AFTN. TWO MAIN AREAS OF PCPN - ONE OVER THE EAST IN THE WARM CONVEYER, AND ANOTHER OVER NW NYS WHERE WEAK DEFORMATION IS OCCURING IN THE NW QUAD OF THE UPR LOW. THE LATTER AREA OF PCPN IS TRYING TO LIFT OUT OF THE FINGER LAKES, BUT -RA ACRS SE SXNS SHUD PERSIST FOR MUCH OF THE AFTN. WILL MONITOR AMTS BUT ATTM DO NOT XPCT ANY PRBLMS WITH RAINFALL ACRS SE ZONES. WE XPCT SHRA TO DVLP THIS AFTN UNDER THE CLOSED LOW AS IT'S ASSCD -14C COLD POOL MOVS INTO THE RGN, BUT BREAKS OF SUNSHINE THIS AFTN WILL BE HARD TO COME BY DUE TO THE LOW LVL MSTR, SO TSRA SHUD REMAIN ISOLD. MAY HAVE TO LOWER MAXES A FEW DEG, OTRW WILL PRETTY MUCH STAY WITH THE CRNT FCST, WITH LIKELY TO CAT POPS THIS AFTN. PREV AFD BLO. COOL UL TROF IS ROTATING INTO NY/PA AS FORECAST. SHOWERS ARE OVERSPREADING THE REGION AS THE MAIN SHORT WAVE ADVANCES AND JET EXITS TO THE EAST. MOST OF THE RAIN ACTIVITY IS LIGHT, THOUGH THERE IS EMBEDDED MODERATE SHOWER ACTIVITY INVOF SHORT WAVE. WE ARE CONTINUING WITH PREVIOUS THINKING THAT COLD CORE ALOFT COULD PROVIDE ENOUGH MID LEVEL INSTABILITY FOR WIDELY SCT OR ISOLATED THUNDER TODAY. PLENTY OF LIGHTNING EXISTED ON MAP LATE LAST EVENING BUT HAS DIED OFF OVERNIGHT. I EXPECT CONVECTION WILL INCREASE A BIT AS WE MOVE INTO THE DAYLIGHT HOURS. MAIN "CHANGE" TODAY WAS TO INCREASE POPS TO CAT. IT IS AN UNFORTUNATE DESCRIPTION, AS ALTHOUGH THE OCCASIONAL SHOWER IS A GIVEN, THE QPF WILL BE QUITE LIGHT. KEEPING POPS IN THE FORECAST FOR FRIDAY WITH SOME STRAGGLERS FORECAST OVER SE FA DURING THE EVENING. PROXIMITY OF UPPER TROF AND PLENTY OF LL MOISTURE SUGGESTS PLENTY OF CLOUDS REGARDLESS. WE BEGIN TO CLEAR OUT EARLY SATURDAY BUT EVEN THEN IT LOOKS LIKE A PARTLY SUNNY DAY, RATHER THAN AMPLE SUN AS ONCE THOUGHT. DJP && .LONG TERM /FRIDAY NIGHT - WED/... MODELS CONTINUE TREND OF SLOWING PROGRESS OF H5 LOW EJECTING OFF THE NEW JERSEY COAST. WITH THIS IN MIND WILL SLOW CLEARING TREND FRIDAY NIGHT AND CONTINUE WITH LOW CHC POPS FAR SE FA THROUGH MIDNIGHT. FOR THE REMAINDER OF THE EXTENDED, MEDIUM RANGE MODELS IN GOOD AGREEMENT. WITH FLAT UPPER LEVEL RIDGE AND SFC HIGH PRESSURE IN VCNTY, A PERIOD OF DRY/WARM WEATHER WILL PERSIST SATURDAY THROUGH MONDAY. MONDAY NIGHT IS THE NEXT CHC FOR PRECIP AS SFC LOW PRESSURE MOVES INTO THE UPPER GREAT LAKES. FROPA WITH THIS SYSTEM IS EXPECTED ON TUESDAY WITH LINGERING SHOWERS INTO WEDNESDAY. RRM && .AVIATION /141200Z TO 151200Z/... MVFR CONDITIONS DUE PRIMARILY TO CIGS WILL PERSIST OVER THE AREA THROUGH MIDDAY WITH OCCASIONAL IFR CONDITIONS AT KBGM. THIS AFTERNOON PRECIPITATION WILL BECOME MORE SCATTERED WITH VFR CONDITONS AT KSYR/KELM/KAVP AND MVFR AT KUCA/KITH/KBGM DUE TO CIGS. OVERNIGHT CONFIDENCE IS LOW WITH VFR CONDITIONS MOST LIKELY BUT EXPECT A WIDE RANGE OF FLIGHT CATEGORIES WITH EVEN IFR POSSIBLE. RRM && .BGM WATCHES/WARNINGS/ADVISORIES... .NY...NONE. .PA...NONE. $$ ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1129 AM EDT THU SEP 14 2006 .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... MODELS CONTINUE TO EXHIBIT AN UPPER RIDGE AXIS OVER THE EAST COAST STATES SUNDAY NIGHT INTO MONDAY WITH A SURFACE HIGH POSITION DRIFTING OFF THE SOUTHEAST COAST. THIS MAINTAINS SUBSIDENCE WARMING AND DRYING ALOFT AND ABOVE NORMAL TEMPERATURES WITH WEST SOUTHWEST FLOW NEAR THE SURFACE. MON NIGHT-TUE...THE COLUMN DESTABILIZES AND MOISTENS AS A LARGE SCALE TROUGH ALOFT MOVES INTO THE OHIO AND TENNESSEE VALLEYS. THE MODELS ARE IN FAIR AGREEMENT WITH A COLD FRONTAL PASSAGE SOMETIME ON TUE...SOMEWHAT FASTER THAN THE MODEL CONSENSUS FROM YESTERDAY. SHOWER CHANCES OF WILL BE HIGHEST FOR TUE WITH LESSER CHANCES EITHER SIDE. 12-HOUR POPS OF 30 PERCENT SHOULD SUFFICE GIVEN THE WESTERLY COMPONENT IN THE LOW LEVEL GEOSTROPHIC FLOW AND THE EXPECTED MORE WIDELY SCATTERED NATURE OF THE SHOWERS. RELATIVE STABILITY IN THE MID LEVELS OF LESS THAN 5.5 DEG/KM SHOULD NEGATE MENTION OF THUNDERSTORMS. FOLLOWING ABOVE NORMAL MIN TEMPERATURES MON NIGHT... CLOUDINESS AND A TRANSITIONAL AIRMASS SHOULD LOWER MAX READINGS ON TUE. FOR TUE NIGHT-THU...THE GFS APPEARS TO BE THE MODEL OF CHOICE BY HPC THOUGH MAJOR DIFFERENCES EXIST AMONG THE MEDIUM RANGE MODEL SOLUTIONS WHICH ADDS UNCERTAINTY TO DAYS 6 AND 7. THE GFS QUICKLY FLATTENS THE LARGE SCALE TROUGH TO AN ALMOST ZONAL WESTERLY FLOW MIDWEEK WHILE OTHER MODELS FAVOR A LARGE AMPLITUDE TROUGH TO REMAIN OVER THE EASTERN U.S. GIVEN THE UNCERTAINTIES...CLIMATOLOGY WILL WEIGH HEAVY IN THE FORECAST CONDITIONS FOR THIS LATTER PERIOD. -RFG && && .PREV DISCUSSION... (ISSUED 1045 AM EDT THU SEP 14 2006) SHORT TERM /REST OF TODAY/... CHALLENGING FORECAST THIS MORNING...AS IT USUALLY IS WITH DEMISE OF RESIDUAL COOL DOME POOL IN PLACE OVER CENTRAL NC. MSAS AND HAND SFC ANALYSIS SHOWS A FRONTAL BOUNDARY BISECTING THE CWA INTO TWO DISTINCT AIRMASS REGIMES WITH A WEAK SFC WAVE LIFTING NORTH ALONG THE BOUNDARY. EAST OF THE BOUNDARY...AND IN THE WARM SECTOR...INTERMITTENT PERIODS OF LIGHT RAIN OR HEAVY DRIZZLE WILL CONTINUE THROUGH AROUND NOON WITH THE SFC WAVE FEATURE BRINGING A BRIEF PERIOD OF HEAVIER SHOWER ACTIVITY IN THE COASTAL PLAIN AS IT RIDES NORTH ALONG THE BOUNDARY. DIMINISHING POPS IN THE AFTERNOON FROM WEST TO EAST...WITH WEST OF THE BOUNDARY AND IN THE RESIDUAL COOL DOME... CURRENT SATELLITE IMAGERY INDICATES GOOD MIXING OCCURRING OVER THE FOOTHILLS AND WESTERN PIEDMONT FROM ISENTROPIC DOWNGLIDE AND RESULTANT SUBSIDENCE. SHORT TERM MODELS ARE NOT HANDLING THIS ASPECT WELL...WHICH IS USUALLY THE CASE. RUC AND MESOETA FORECAST SOUNDINGS INDICATED CAPPING INVERSION AOA 725MB OBSERVED IN 12Z/14 GSO RAOB...WILL MAINTAIN...LOCKING IN RESIDUAL COOL POOL AND RESIDUAL MOISTURE THROUGH THE MIXING LAYER. THE BIGGEST UNCERTAINTY IS WHETHER THE CLOUDS WILL FILL BACK IN WITH SURFACE HEATING...AND THE IMPLICATIONS ON FORECAST HIGHS TODAY. CURRENT FORECAST HIGHS LOOKS TO BE THE WARMEST SCENARIO...SEEING DECENT INTERVALS OF SUN. WILL LOWER MAX TEMPS DOWN A CATEGORY TO BE MORE IN LINE WITH COOLER LAMP GUIDANCE. WILL KEEP SKIES MOSTLY CLOUDY IN CENTRAL AND EASTERN SECTIONS WITH VARIABLY CLOUD IN THE WEST. OTHERWISE WILL REMOVE POPS ACROSS THE CENTRAL PIEDMONT BY AROUND NOON...KEEPING A SLIGHT CHANCE OF SHOWERS IN THE COASTAL PLAIN THROUGH THE AFTERNOON. PREV DISCUSSION... (ISSUED 258 AM EDT THU SEP 14 2006) SHORT TERM /TODAY THROUGH SATURDAY NIGHT/... LIGHT RAIN WITH POCKETS OF MODERATE TO HEAVY RAIN (EVEN A FEW LIGHTNING STRIKES SOUTHWEST SECTIONS)CONTINUES OVER THE CWA EARLY THIS MORNING IN RESPONSE TO FRONTAL BOUNDARY/ISENTROPIC LIFT/UPPER DIVERGENCE AND JET STREAK. ADDITIONAL SURFACE WAVE WILL LIFT NORTHEAST THROUGH EASTERN CAROLINAS THIS MORNING. EXPECT RAIN TO PULL OUT OF THE AREA LATER THIS MORNING...ENDING FROM WEST TO EAST. MODELS SUGGESTING POTENTIAL FOR CONVECTION EASTERN/SOUTHEAST TIER SECTION THIS AFTERNOON AS SURFACE WAVE MOVES THROUGH AS LI'S -2/-3 AND CAPES 1000-2000. AT THIS POINT THINK VERY ISOLATED AT BEST. THIS WOULD BE MORE POSSIBLE IF GET SOME BREAKS AND ALLOW FOR AFTERNOON HEATING. MID LEVELS DRYING OUT IN THE AFTERNOON INTO TONIGHT. HOWEVER FORECAST SOUNDINGS/TIME HEIGHT CROSS SECTION SHOW CONSIDERABLE MOISTURE REMAINING BELOW 700 MB. GFS IS SHOWING MORE DOWNSLOPE FLOW WHILE NAM NORTHEAST AND HIGH MOISTURE. FOR NOW..EXPECT CLEARING TO BE SLOW TODAY. SOME CLEARING DURING THE LATE AFTERNOON/EVENING BUT CLOUDS SHOULD FILL BACK IN OVERNIGHT. SO HAVE GONE WITH CONSIDERABLE CLOUD COVER OVERNIGHT. WITH SLOWER TREND ON CLEARING TODAY...HAVE SHAVED A FEW DEGREES OFF MAX TEMPERATURES. HIGHS RANGING FROM MID 70S NORTHWEST TO NEAR 80 SOUTHEAST. THEN IN TURN WITH MORE CLOUD COVER TONIGHT HAVE RAISED MINS A COUPLE OF DEGREES. FRIDAY THROUGH SATURDAY NIGHT... LITTLE ADJUSTMENTS DURING THIS PERIOD. HIGH PRESSURE DOMINATES WITH TEMPERATURES RETURNING TO SEASONAL NORMS. LONG TERM /SUNDAY THROUGH WEDNESDAY/... CONTINUE DRY SUNDAY AND MONDAY. NEXT FRONT APPROACHING FROM THE WEST. MODELS HAVE SPED UP TIMING OF FRONT MOVING ACROSS AREA...NOW INDICATING MOVING THROUGH TUESDAY/TUESDAY NIGHT. THEN DRY ON WEDNESDAY. WILL GO WITH CHANCE FOR SHOWERS TUESDAY(MAINLY IN THE AFTERNOON) AND TUESDAY NIGHT. DRY ON WEDNESDAY. AVIATION... IFR/MVFR CIGS AND VIS IN LIGHT TO MODERATE RAIN...DRIZZLE AND FOG ARE ANTICIPATED TO LAST THROUGH MID MORNING ACROSS THE CWA. PRECIP WILL END FROM WEST TO EAST AS A NNE-SSW ORIENTED BOUNDARY ASSOC/W WEAK LOW PRESSURE OVER SC BEGINS TO ADVECT EAST. THE TRIAD WILL SEE THE BULK OF PRECIP END BEFORE SUNRISE...THE TRIANGLE AREA AROUND OR SHORTLY AFTER SUNRISE...AND THE COASTAL PLAIN BY MID TO LATE MORNING. CIGS AND VIS WILL BEGIN TO IMPROVE AFTER PRECIP ENDS...WITH MVFR/VFR CONDS EXPECTED IN MOST LOCATIONS BY EARLY TO MID AFTERNOON. HOWEVER...CIGS WILL STILL REMAIN BKN OR OVC INTO TONIGHT...AND A RETURN TO MVFR/IFR CIGS AND VIS IS EXPECTED BETWEEN 04-12Z TOMORROW MORNING. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ LONG TERM...RFG nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1045 AM EDT THU SEP 14 2006 .SHORT TERM /REST OF TODAY/... CHALLENGING FORECAST THIS MORNING...AS IT USUALLY IS WITH DEMISE OF RESIDUAL COOL DOME POOL IN PLACE OVER CENTRAL NC. MSAS AND HAND SFC ANALYSIS SHOWS A FRONTAL BOUNDARY BISECTING THE CWA INTO TWO DISTINCT AIRMASS REGIMES WITH A WEAK SFC WAVE LIFTING NORTH ALONG THE BOUNDARY. EAST OF THE BOUNDARY...AND IN THE WARM SECTOR...INTERMITTENT PERIODS OF LIGHT RAIN OR HEAVY DRIZZLE WILL CONTINUE THROUGH AROUND NOON WITH THE SFC WAVE FEATURE BRINGING A BRIEF PERIOD OF HEAVIER SHOWER ACTIVITY IN THE COASTAL PLAIN AS IT RIDES NORTH ALONG THE BOUNDARY. DIMINISHING POPS IN THE AFTERNOON FROM WEST TO EAST...WITH WEST OF THE BOUNDARY AND IN THE RESIDUAL COOL DOME... CURRENT SATELLITE IMAGERY INDICATES GOOD MIXING OCCURRING OVER THE FOOTHILLS AND WESTERN PIEDMONT FROM ISENTROPIC DOWNGLIDE AND RESULTANT SUBSIDENCE. SHORT TERM MODELS ARE NOT HANDLING THIS ASPECT WELL...WHICH IS USUALLY THE CASE. RUC AND MESOETA FORECAST SOUNDINGS INDICATED CAPPING INVERSION AOA 725MB OBSERVED IN 12Z/14 GSO RAOB...WILL MAINTAIN...LOCKING IN RESIDUAL COOL POOL AND RESIDUAL MOISTURE THROUGH THE MIXING LAYER. THE BIGGEST UNCERTAINTY IS WHETHER THE CLOUDS WILL FILL BACK IN WITH SURFACE HEATING...AND THE IMPLICATIONS ON FORECAST HIGHS TODAY. CURRENT FORECAST HIGHS LOOKS TO BE THE WARMEST SCENARIO...SEEING DECENT INTERVALS OF SUN. WILL LOWER MAX TEMPS DOWN A CATEGORY TO BE MORE IN LINE WITH COOLER LAMP GUIDANCE. WILL KEEP SKIES MOSTLY CLOUDY IN CENTRAL AND EASTERN SECTIONS WITH VARIABLY CLOUD IN THE WEST. OTHERWISE WILL REMOVE POPS ACROSS THE CENTRAL PIEDMONT BY AROUND NOON...KEEPING A SLIGHT CHANCE OF SHOWERS IN THE COASTAL PLAIN THROUGH THE AFTERNOON. && .PREV DISCUSSION... (ISSUED 258 AM EDT THU SEP 14 2006) SHORT TERM /TODAY THROUGH SATURDAY NIGHT/... LIGHT RAIN WITH POCKETS OF MODERATE TO HEAVY RAIN (EVEN A FEW LIGHTNING STRIKES SOUTHWEST SECTIONS)CONTINUES OVER THE CWA EARLY THIS MORNING IN RESPONSE TO FRONTAL BOUNDARY/ISENTROPIC LIFT/UPPER DIVERGENCE AND JET STREAK. ADDITIONAL SURFACE WAVE WILL LIFT NORTHEAST THROUGH EASTERN CAROLINAS THIS MORNING. EXPECT RAIN TO PULL OUT OF THE AREA LATER THIS MORNING...ENDING FROM WEST TO EAST. MODELS SUGGESTING POTENTIAL FOR CONVECTION EASTERN/SOUTHEAST TIER SECTION THIS AFTERNOON AS SURFACE WAVE MOVES THROUGH AS LI'S -2/-3 AND CAPES 1000-2000. AT THIS POINT THINK VERY ISOLATED AT BEST. THIS WOULD BE MORE POSSIBLE IF GET SOME BREAKS AND ALLOW FOR AFTERNOON HEATING. MID LEVELS DRYING OUT IN THE AFTERNOON INTO TONIGHT. HOWEVER FORECAST SOUNDINGS/TIME HEIGHT CROSS SECTION SHOW CONSIDERABLE MOISTURE REMAINING BELOW 700 MB. GFS IS SHOWING MORE DOWNSLOPE FLOW WHILE NAM NORTHEAST AND HIGH MOISTURE. FOR NOW..EXPECT CLEARING TO BE SLOW TODAY. SOME CLEARING DURING THE LATE AFTERNOON/EVENING BUT CLOUDS SHOULD FILL BACK IN OVERNIGHT. SO HAVE GONE WITH CONSIDERABLE CLOUD COVER OVERNIGHT. WITH SLOWER TREND ON CLEARING TODAY...HAVE SHAVED A FEW DEGREES OFF MAX TEMPERATURES. HIGHS RANGING FROM MID 70S NORTHWEST TO NEAR 80 SOUTHEAST. THEN IN TURN WITH MORE CLOUD COVER TONIGHT HAVE RAISED MINS A COUPLE OF DEGREES. FRIDAY THROUGH SATURDAY NIGHT... LITTLE ADJUSTMENTS DURING THIS PERIOD. HIGH PRESSURE DOMINATES WITH TEMPERATURES RETURNING TO SEASONAL NORMS. LONG TERM /SUNDAY THROUGH WEDNESDAY/... CONTINUE DRY SUNDAY AND MONDAY. NEXT FRONT APPROACHING FROM THE WEST. MODELS HAVE SPED UP TIMING OF FRONT MOVING ACROSS AREA...NOW INDICATING MOVING THROUGH TUESDAY/TUESDAY NIGHT. THEN DRY ON WEDNESDAY. WILL GO WITH CHANCE FOR SHOWERS TUESDAY(MAINLY IN THE AFTERNOON) AND TUESDAY NIGHT. DRY ON WEDNESDAY. AVIATION... IFR/MVFR CIGS AND VIS IN LIGHT TO MODERATE RAIN...DRIZZLE AND FOG ARE ANTICIPATED TO LAST THROUGH MID MORNING ACROSS THE CWA. PRECIP WILL END FROM WEST TO EAST AS A NNE-SSW ORIENTED BOUNDARY ASSOC/W WEAK LOW PRESSURE OVER SC BEGINS TO ADVECT EAST. THE TRIAD WILL SEE THE BULK OF PRECIP END BEFORE SUNRISE...THE TRIANGLE AREA AROUND OR SHORTLY AFTER SUNRISE...AND THE COASTAL PLAIN BY MID TO LATE MORNING. CIGS AND VIS WILL BEGIN TO IMPROVE AFTER PRECIP ENDS...WITH MVFR/VFR CONDS EXPECTED IN MOST LOCATIONS BY EARLY TO MID AFTERNOON. HOWEVER...CIGS WILL STILL REMAIN BKN OR OVC INTO TONIGHT...AND A RETURN TO MVFR/IFR CIGS AND VIS IS EXPECTED BETWEEN 04-12Z TOMORROW MORNING. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...LOCKLEAR nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 405 PM CDT FRI SEP 15 2006 .DISCUSSION... HAVE MADE LITTLE CHANGE TO ONGOING FCST. STILL, AM PRESENTED WITH THREE PROBLEMS IN IMMEDIATE FORECAST. FIRST CONCERN IS WIND TODAY. APPEARS WILL BE PLENTY OF MIXING AS GRADIENT REMAINS STRONG. HOWEVER, MAY NOT BE QUITE ENOUGH GRADIENT TO JUSTIFY A WIND ADVISORY. WILL BE CLOSE HOWEVER AND WILL NEED TO BE MONITORED FOR TRENDS DURING THE DAY. ANY INCREASE IN CLOUDINESS WILL ALSO MITIGATE STRONGER SUSTAINED SURFACE WINDS AND/OR GUSTS. HAVE INCREASED THE WIND GUSTS IN THE FORECAST FOR TODAY. AM BANKING ON MIXING HEIGHTS HIGH ENOUGH TO BRING STRONGER GUSTS TO THE SURFACE. NEXT PROBLEM IS POTENTIAL FOR CONVECTION TODAY. RUCII MODEL CONTINUES TO SHOW CONSIDERABLE CONVECTIVE PRECIPITATION THIS MORNING BUT SO FAR, THIS HAS FAILED TO DEVELOP. LOOKING AT SOUNDINGS FROM THE RUC AND ALSO THE NAM...STILL SEE ENOUGH POTENTIAL FOR A BIT OF ELEVATED CONVECTION THIS MORNING. SO, WILL MAINTAIN SLIGHT CHANCE POPS PORTIONS OF WESTERN CWA. THIRD PROBLEM IS POTENTIAL FOR PRECIPITATION WELL BEHIND FRONTAL BOUNDARY ON SUNDAY. GFS CERTAINLY IMPLIES THIS WITH LESS SLOPE TO FRONTAL BOUNDARY AND BETTER POTENTIAL FOR PRECIP AS UPPER TROF MOVES IN. 00Z RUN OF NAM QUITE DRY LATE SUNDAY...BUT LATEST 06Z RUN MUCH LESS SO AND TRENDING TOWARD THE GFS. DID NOT CHANGE THESE PARTS OF THE FORECAST...BUT THIS ALSO BEARS WATCHING IN NEXT SEVERAL RUNS. OTHER PARTS OF FORECAST APPEAR ON LINE. AS MENTIONED, ACTUAL SURFACE FRONTAL PASSAGE WELL PRESENTED ON GRIDS...HOWEVER SLOPE OF FRONT IN QUESTION AND THAT WILL DICTATE AMOUNT OF CLOUDS AND CHANCES FOR PCPN SUNDAY AND SUNDAY NIGHT. && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ks AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE LOUISVILLE KY 549 AM EDT FRI SEP 15 2006 ...DENSE FOG ADVISORY THIS MORNING... .MESO UPDATE... WILL CONTINUE DENSE FOG ADVISORY FOR ENTIRE CWA UNTIL 14Z. MANY ASOS/AWOS STATIONS AT OR NEAR 1/4SM. THE ONLY EXCEPTION IS A BUBBLE OF HIGHER VSBYS FROM FT KNOX AND LOUISVILLE UP INTO PARTS OF SRN IND...WHERE SENSORS ARE BETWEEN 3 AND 6SM. STILL THERE ARE LIKELY SOME PATCHES OF DENSE FOG IN THIS AREA IN THE FAVORED SPOTS. CS && .PREV DISCUSSION... (ISSUED 245 AM EDT FRI SEP 15 2006) SHORT TERM (TODAY-TONIGHT)... LARGE AREA OF SFC HIGH PRES STRETCHING FROM THE GREAT LAKES SOUTHWARD INTO THE LOWER OHIO VALLEY EARLY THIS MORNING. THIS IS LEADING TO NEARLY CALM WINDS AT THE SFC...HOWEVER JUST OFF THE DECK PER VWP/ACARS DATA...10-20KT WINDS ARE OBSERVED IN THE LOWEST 1-2KFT AGL. EVEN WITH THESE WINDS...SOME AREAS OF DENSE FOG HAVE ALREADY DEVELOPED...MAINLY IN THE RURAL/FOG PRONE AREAS. 11-3.9 SAT PIX INDICATING MOST WIDESPREAD FOG IS IN AREAS S/E OF A BWG-LEX LINE AS OF 630Z. LATEST RUC INDICATES WIDESPREAD M1/4SM VSBYS DEVELOPING AFTER 9Z AS BOUNDARY LAYER WINDS LIGHTEN SLIGHTLY. WILL ISSUE A DENSE FOG ADVISORY THROUGH 14Z FOR ENTIRE CWA. BASED ON RUC DATA FOG SHOULD MIX OUT BY 14-15Z THIS MORNING... LEADING TO MOSTLY SUNNY SKIES PER NAM FCST SOUNDINGS. A FEW FLAT CU ARE EXPECTED DURING THE LATE MORNING AND AFTN HOURS...CENTERED AROUND 3KFT. TONIGHT...SKIES SHOULD LARGELY BE CLEAR WITH PERHAPS SOME WISPS OF CIRRUS DROPPING IN FROM THE NW. NAM SHOWING HIGHER RH AROUND 300MB AFTER 2Z. PATCHY FOG POSSIBLE AGAIN LATE TONIGHT. REGARDING TEMPERATURES...CONSENSUS OF NAM/GFS MOS GUIDANCE INDICATES HIGHS TODAY FROM THE UPPER 70S TO LOWER 80S AND THIS SEEMS OK. WITH CLR SKIES TONIGHT...SHELTERED/VALLEY AREAS MAY DROP INTO THE LOWER 50S...WITH MID/UPPER 50S ELSEWHERE. CS LONG TERM (SATURDAY-THURSDAY)... SATURDAY AND SUNDAY... LOWER OHIO VALLEY WILL UNDER A THIN UPPER RIDGE...WHICH IS BEING SQUEEZED BETWEEN A PERSISTENT WEAK TROUGH JUST OFF THE MID ATLANTIC COAST...AND A MUCH STRONGER FULL LATITUDE TROUGH SLOWLY PROGRESSING INTO THE HIGH PLAINS SATURDAY AND SUNDAY. EXPECT WARM...LATE SUMMERLIKE TEMPERATURES WITH PLENTY OF SUN...AND CLEAR NIGHTS. GULF MOISTURE THIS WEEKEND WILL BE CONFINED ALONG THE GULF COAST...ALTHOUGH SOME WILL BEGIN A NORTHWARD RETURN ON SUNDAY ACROSS THE LOWER MISSISSIPPI VALLEY AND INTO THE WESTERN GREAT LAKES. AT THE SURFACE...EXPECT LIGHT EAST WINDS SATURDAY THAT WILL VEER TO THE SOUTH SUNDAY AS HIGH PRESSURE MOVES EAST OF THE GREAT LAKES. SOUTH WINDS WILL INCREASE SUNDAY AFTERNOON AS A SURFACE TROUGH EXTENDING FROM AN OCCLUDED FRONT ACROSS MICHIGAN SOUTHWESTWARD ACROSS MISSOURI MOVES EASTWARD. MONDAY... 00Z OPERATIONAL GFS...LIKE ITS 00Z RUN YESTERDAY...IS DEEPER THAN ITS ENSEMBLE MODELS WITH THE CLOSED LOW EXPECTED TO MOVE ACROSS MINNESOTA MONDAY. BOTH NAM AND GFS BRING A THIN STRIP OF HIGH PRECIPITABLE WATER RIGHT ALONG A SHARP COLD FRONT EXPECTED TO MOVE ACROSS OHIO RIVER MONDAY. SURFACE BASED INSTABILITY WILL BE HIGHLY DEPENDENT ON EXACT TIMING OF FRONT...AND ANY SOLAR HEATING AVAILABLE MONDAY AHEAD OF THIS BOUNDARY. HOWEVER...UPPER DYNAMICS WILL SUGGEST GOOD CHANCE OF LINEAR CONVECTION RIGHT ALONG THE SOUTHEASTWARD MOVING BOUNDARY AND WILL MAINTAIN 50 POPS FOR CONVECTION MONDAY. TUESDAY THROUGH THURSDAY... LATEST ECMWF IS THE COOLEST WITH THE AIR BEHIND THE FRONT TUESDAY...AND BOTH OPERATIONAL MODELS HAVE BACKED OFF THE DEPTH OF THE UNSEASONABLY COLD AIR MASS EXPECTED TO MOVE INTO THE UPPER MIDWEST MONDAY. STILL EXPECT A DISTINCT COOLDOWN TUESDAY AND WEDNESDAY ACROSS THE LOWER OHIO VALLEY. BY EARLY TUESDAY...DEEP OCCLUDED CYCLONE WILL BE LOCATED OVER ONTARIO...WITH COLD FRONT ALONG THE SOUTHERN APPALACHIANS. CLEARING SHOULD PROCEED PRETTY RAPIDLY EARLY ACROSS REGION TUESDAY AS DRY AIR DESCENDS BEHIND THE DEPARTING FRONT. NORTHWEST WINDS WILL DIMINISH SOMEWHAT TUESDAY NIGHT AS SURFACE HIGH PRESSURE MOVES CLOSER. WEDNESDAY MORNING LOOKS QUITE COOL WITH UPPER 40S POSSIBLE UNDER MOSTLY CLEAR SKIES. WEDNESDAY AND THURSDAY WILL CONTINUE COOL WITH HIGHS IN GENERAL BETWEEN 5 AND 8 DEGREES BELOW NORMAL. JSD LMK WATCHES/WARNINGS/ADVISORIES... KY...DENSE FOG ADVISORY UNTIL 14Z (10AM EDT) ALL ZONES. IN...DENSE FOG ADVISORY UNTIL 14Z (10AM EDT) ALL ZONES. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 245 AM EDT FRI SEP 15 2006 ...DENSE FOG ADVISORY THIS MORNING... .SHORT TERM (TODAY-TONIGHT)... LARGE AREA OF SFC HIGH PRES STRETCHING FROM THE GREAT LAKES SOUTHWARD INTO THE LOWER OHIO VALLEY EARLY THIS MORNING. THIS IS LEADING TO NEARLY CALM WINDS AT THE SFC...HOWEVER JUST OFF THE DECK PER VWP/ACARS DATA...10-20KT WINDS ARE OBSERVED IN THE LOWEST 1-2KFT AGL. EVEN WITH THESE WINDS...SOME AREAS OF DENSE FOG HAVE ALREADY DEVELOPED...MAINLY IN THE RURAL/FOG PRONE AREAS. 11-3.9 SAT PIX INDICATING MOST WIDESPREAD FOG IS IN AREAS S/E OF A BWG-LEX LINE AS OF 630Z. LATEST RUC INDICATES WIDESPREAD M1/4SM VSBYS DEVELOPING AFTER 9Z AS BOUNDARY LAYER WINDS LIGHTEN SLIGHTLY. WILL ISSUE A DENSE FOG ADVISORY THROUGH 14Z FOR ENTIRE CWA. BASED ON RUC DATA FOG SHOULD MIX OUT BY 14-15Z THIS MORNING... LEADING TO MOSTLY SUNNY SKIES PER NAM FCST SOUNDINGS. A FEW FLAT CU ARE EXPECTED DURING THE LATE MORNING AND AFTN HOURS...CENTERED AROUND 3KFT. TONIGHT...SKIES SHOULD LARGELY BE CLEAR WITH PERHAPS SOME WISPS OF CIRRUS DROPPING IN FROM THE NW. NAM SHOWING HIGHER RH AROUND 300MB AFTER 2Z. PATCHY FOG POSSIBLE AGAIN LATE TONIGHT. REGARDING TEMPERATURES...CONSENSUS OF NAM/GFS MOS GUIDANCE INDICATES HIGHS TODAY FROM THE UPPER 70S TO LOWER 80S AND THIS SEEMS OK. WITH CLR SKIES TONIGHT...SHELTERED/VALLEY AREAS MAY DROP INTO THE LOWER 50S...WITH MID/UPPER 50S ELSEWHERE. CS .LONG TERM (SATURDAY-THURSDAY)... SATURDAY AND SUNDAY... LOWER OHIO VALLEY WILL UNDER A THIN UPPER RIDGE...WHICH IS BEING SQUEEZED BETWEEN A PERSISTENT WEAK TROUGH JUST OFF THE MID ATLANTIC COAST...AND A MUCH STRONGER FULL LATITUDE TROUGH SLOWLY PROGRESSING INTO THE HIGH PLAINS SATURDAY AND SUNDAY. EXPECT WARM...LATE SUMMERLIKE TEMPERATURES WITH PLENTY OF SUN...AND CLEAR NIGHTS. GULF MOISTURE THIS WEEKEND WILL BE CONFINED ALONG THE GULF COAST...ALTHOUGH SOME WILL BEGIN A NORTHWARD RETURN ON SUNDAY ACROSS THE LOWER MISSISSIPPI VALLEY AND INTO THE WESTERN GREAT LAKES. AT THE SURFACE...EXPECT LIGHT EAST WINDS SATURDAY THAT WILL VEER TO THE SOUTH SUNDAY AS HIGH PRESSURE MOVES EAST OF THE GREAT LAKES. SOUTH WINDS WILL INCREASE SUNDAY AFTERNOON AS A SURFACE TROUGH EXTENDING FROM AN OCCLUDED FRONT ACROSS MICHIGAN SOUTHWESTWARD ACROSS MISSOURI MOVES EASTWARD. MONDAY... 00Z OPERATIONAL GFS...LIKE ITS 00Z RUN YESTERDAY...IS DEEPER THAN ITS ENSEMBLE MODELS WITH THE CLOSED LOW EXPECTED TO MOVE ACROSS MINNESOTA MONDAY. BOTH NAM AND GFS BRING A THIN STRIP OF HIGH PRECIPITABLE WATER RIGHT ALONG A SHARP COLD FRONT EXPECTED TO MOVE ACROSS OHIO RIVER MONDAY. SURFACE BASED INSTABILITY WILL BE HIGHLY DEPENDENT ON EXACT TIMING OF FRONT...AND ANY SOLAR HEATING AVAILABLE MONDAY AHEAD OF THIS BOUNDARY. HOWEVER...UPPER DYNAMICS WILL SUGGEST GOOD CHANCE OF LINEAR CONVECTION RIGHT ALONG THE SOUTHEASTWARD MOVING BOUNDARY AND WILL MAINTAIN 50 POPS FOR CONVECTION MONDAY. TUESDAY THROUGH THURSDAY... LATEST ECMWF IS THE COOLEST WITH THE AIR BEHIND THE FRONT TUESDAY...AND BOTH OPERATIONAL MODELS HAVE BACKED OFF THE DEPTH OF THE UNSEASONABLY COLD AIR MASS EXPECTED TO MOVE INTO THE UPPER MIDWEST MONDAY. STILL EXPECT A DISTINCT COOLDOWN TUESDAY AND WEDNESDAY ACROSS THE LOWER OHIO VALLEY. BY EARLY TUESDAY...DEEP OCCLUDED CYCLONE WILL BE LOCATED OVER ONTARIO...WITH COLD FRONT ALONG THE SOUTHERN APPALACHIANS. CLEARING SHOULD PROCEED PRETTY RAPIDLY EARLY ACROSS REGION TUESDAY AS DRY AIR DESCENDS BEHIND THE DEPARTING FRONT. NORTHWEST WINDS WILL DIMINISH SOMEWHAT TUESDAY NIGHT AS SURFACE HIGH PRESSURE MOVES CLOSER. WEDNESDAY MORNING LOOKS QUITE COOL WITH UPPER 40S POSSIBLE UNDER MOSTLY CLEAR SKIES. WEDNESDAY AND THURSDAY WILL CONTINUE COOL WITH HIGHS IN GENERAL BETWEEN 5 AND 8 DEGREES BELOW NORMAL. JSD && .LMK WATCHES/WARNINGS/ADVISORIES... KY...DENSE FOG ADVISORY UNTIL 14Z (10AM EDT) ALL ZONES. IN...DENSE FOG ADVISORY UNTIL 14Z (10AM EDT) ALL ZONES. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 540 AM EDT FRI SEP 15 2006 .UPDATE... HEAT FLUX FROM STRATUS DECK HAS REALLY TAKEN A TOLL ON FOG DEVELOPMENT AND EXISTING DENSE FOG. VISIBILITIES IN AREAS WENT FROM LESS THEN A 1/4 MILE TO OVER 10 IN LESS THEN AN HOUR. LOW CLOUDS HAVE MADE IT TO ABOUT CARO IN TUSCOLA COUNTY SOUTH THROUGH PONTIAC TO DETROIT. LOOKS LIKE THE WESTWARD ADVANCEMENT IS SLOWING BUT SHOULD CONTINUE SOUTH. WILL DISCONTINUE DENSE FOG ADVISORY FROM WAYNE COUNTY ON NORTH AND EAST. && .SHORT TERM...TODAY AND TONIGHT SURFACE HIGH AND UPPER RIDGE WILL BE OVER HEAD TODAY AND TONIGHT. FORECAST PROBLEM WILL BE FOG AND CLOUD COVER THIS MORNING. LARGE SHIELD OF LOW STRATUS HAS BEEN WORKING BACK AROUND UPPER LOW SYSTEM OVER PENNSYLVANIA INTO THE EASTERN THUMB AND IS CONTINUING TO SPREAD SOUTH AND WESTWARD UNDER INVERSION. THIS IS ALSO BEING HELPED BY WEAK SURFACE TROUGHING EXTENDING BACK WEST INTO THUMB. GFS SEEMS TO HAVE THE BEST HANDLE ON THIS LOOKING AT THE 925-950MB MOISTURE FIELD. LOW CLOUDS WILL LIKELY MAKE IT NO FURTHER WEST THEN US23/US23/I75 LINE. WILL CONTINUE THE DENSE FOG ADVISORY UNTIL 14Z AS MOST OBSERVATIONS SHOWING VISIBILITIES 1/4 MILE OR LESS...EXCEPTIONS HAVE BEEN MOST OF WAYNE COUNTY WHERE URBAN HEAT ISLAND AFFECT SEEMS TO HAVE KEPT DEW POINT SPREAD APART FAR ENOUGH TO LIMIT FOG DEVELOPMENT SO FAR AND EASTERN MACOMB COUNTY WHERE CLOUD COVER HAS PREVENT DECENT RADIATIONAL COOLING. STILL SEVERAL HOURS TO GO BEFORE SUNRISE SO DO EXPECT SOME DEGREE OF FOG TO DEVELOP IN THESE AREAS BUT MORE OF PATCHY DENSE FOG THEN WIDESPREAD. FOG AND CLOUDS WILL MIX AND DISSIPATE OUT BY NOON. MODEL SOUNDINGS SHOW ENOUGH INSTABILITY AND LOW LEVEL MOISTURE ACROSS EASTERN PORTIONS OF CWA TO GENERATE SCT-BKN CU THIS AFTERNOON SO WILL CARRY PARTLY CLOUDY THOSE AREAS AND MOSTLY SUNNY ELSEWHERE. SHOULD HAVE CLEAR SKIES TONIGHT WITH OUT ANY LOW LEVEL CLOUD INTRUSION LIKE OVERNIGHT. EXPECT GOOD RADIATIONAL COOLING AGAIN TONIGHT SO WILL CARRY AREAS OF FOG. NOT EXPECTING WIDESPREAD DENSE FOG BUT WILL LIKELY SEE PATCHY DENSE FOG. WILL GO WITH WARMER GFS NUMBERS AS MET GUIDANCE UNDER DID YESTERDAYS HIGHS AND SEEMS A BIT LOW FOR TODAY. && .LONG TERM...SATURDAY THROUGH THURSDAY A BRIEF WARM UP THEN AUTUMN CONDITIONS SETTLE INTO THE GREAT LAKES FOR NEXT WEEK (BUT NOT AS EMPHATIC PER THE GFS). LARGE SCALE PATTERN SHIFT IS UNDERWAY WITH DEEP AND COLD TROUGH ACROSS THE PACIFIC NORTHWEST INTO THE FOUR CORNERS REGION AND SURFACE LEE-CYCLOGENESIS ACROSS THE WESTERN DAKOTAS. IN TURN THE DOWNSTREAM RIDGE CONTINUES TO AMPLIFY WITH STRENGTHENING SURFACE HIGH ACROSS THE MIDWEST AND TENNESSEE VALLEY THAT WILL REMAIN IN PLACE THROUGH SATURDAY. MODELS ARE CONSISTENT WITH OCCLUDED FRONT IN THE GREAT LAKES SUNDAY NIGHT INTO MONDAY MORNING. THE NMM/CANADIAN SUGGEST 500MB WAVE ON THE ENTRANCE SIDE OF THE JET WILL AMPLIFY AND TRACK INTO THE STATE LATE SUNDAY BUT CONSENSUS FROM THE GFS/ECMWF SUGGEST HOLDING OFF UNTIL SUNDAY NIGHT GIVEN STRENGTH OF UPSTREAM TROUGH AND TRENDS SUGGEST A LITTLE SLOWER PROGRESS. THIS CONTINUES WITH THE CHANCE FOR SHOWERS/THUNDERSTORMS SUNDAY NIGHT INTO MONDAY MORNING AND WE WILL RAISE POPS A LITTLE MORE. DEEP THETA-E ADVECTION ALONG WITH 30-40KTS LOW LEVEL JET SUPPORTS THE HIGHER PROBABILITIES AND WITH ENTRANCE REGION DYNAMICS TO AID IN ADDITIONAL LIFT. TEMPERATURES WILL BE MILD FOR THIS TIME OF THE YEAR WITH THE OFFICIAL START TO AUTUMN THIS WEEKEND. NOT TO WORRY AS THE CALENDAR WILL CATCH UP QUICKLY EARLY NEXT WEEK WITH FROPA EXPECTED BY MONDAY AFTERNOON AND COLD ADVECTION TO PERUSE. THE GFS SEEMS TO BE OVERDEVELOPED WITH THE CLOSED 500MB LOW AND WE PREFER THE MORE OPEN NATURE SIMILAR TO THE ECMWF/CANADIAN. THIS SHOULD KEEP THOSE NEGATIVE 850MB TEMPS A BIT IN CHECK (FOR NOW) ACROSS THE STATE BUT NEVERTHELESS LOWER SINGLE DIGIT READINGS EMBEDDED WITHIN THE CYCLONIC FLOW WILL PROVIDE UNSETTLED CONDITIONS THROUGH MID-WEEK WITH THE CHANCE FOR RAIN SHOWERS AND SOME LAKE EFFECT RAIN SHOWERS FROM LAKE MICHIGAN. THEN FOLLOWING THE ECMWF/CANADIAN IDEA OF BUILDING HEIGHTS AND SURFACE PRESSURES TOWARD THE END OF THE WEEK ACROSS THE NORTHERN PLAINS AND EVENTUALLY INTO THE GREAT LAKES REGION. HOWEVER...THIS WILL NOT BE A CLEAN FORECAST AS INDICATIONS ARE WE QUICKLY TRANSITION INTO A ZONAL FLOW WITH A FURTHER SOUTH POSITION OF THE MAIN UPPER JET. LIKELY SEE MORE CLOUDS BUT WILL REFRAIN FROM THE MENTION OF PRECIP AT THIS TIME. SUMMER IS INDEED COMING TO AN END. && .PREV DISCUSSION...ISSUED 100 AM EDT FRI SEP 15 2006 AVIATION... REDUCED VISIBILITIES IN FOG WILL BE A BIG AVIATION CONCERN THIS MORNING AS HIGH PRESSURE REMAINS CENTERED OVER THE STATE. CLEAR SKIES...LIGHT WINDS AND HIGH SOIL MOISTURE HAS SET THE STAGE FOR OPTIMAL RADIATIONAL FOG DEVELOPMENT THIS MORNING. WILL CONTINUE TO CARRY SEVERAL HOURS OF QUARTER MILE VISIBILITY AT FNT AND MBS. THE COMBINATION OF THE URBAN HEAT ISLAND AFFECT AND A LITTLE STRONGER NORTHERLY WINDS JUST ATOP THE NOCTURNAL INVERSION MAY BE ENOUGH TO PREVENT DENSE FOG AT DTW AND DET. AS OF 04Z...THERE IS A SOLID STRATUS DECK BASED AROUND 1200FT MOVING INTO MACOMB COUNTY. THE 00Z RUC NOW HAS THE BEST HANDLE ON THIS CLOUD COVER...WHICH BRINGS IT INTO DET BY 07Z. THE RUC DOES NOT SUGGEST MUCH ADDITIONAL WESTWARD MOVEMENT TO CLOUDS WITH THE LOW LEVEL WINDS FORECAST TO BE MORE NORTHERLY AT DETROIT. AT THIS POINT...WILL BRING THE STRATUS DECK INTO DET BUT HOLD OFF AT DTW. THE AFFECT OF THIS STRATUS DECK WILL BE TO REDUCE THE FOG DEVELOPMENT AND ALLOW SURFACE VISIBILITY TO INCREASE. BASED ON OBS IN WISCONSIN YESTERDAY AND GIVEN THE LOWER MID SEPTEMBER SUN ANGLE...FOG SHOULD NOT MIX OUT UNTIL 13-15Z. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...DENSE FOG ADVISORY...MIZ047-MIZ048-MIZ049-MIZ053-MIZ054-MIZ055- MIZ060-MIZ061-MIZ062-MIZ063-MIZ068-MIZ069-MIZ070-MIZ075- MIZ076-MIZ082-MIZ083 UNTIL 10 AM FRIDAY. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...DRC LONG TERM....BGM 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 GAYLORD MI 500 AM EDT FRI SEP 15 2006 .UPDATE...EXPANDING DENSE FOG ADVIS INTO OTSEGO. NO OTHER CHANGES. NOT WILLING TO GIVE UP ON HEADLINE YET WEST OF US-131...THOUGH TO THIS POINT TVC AND THE COAST HAVE NOT SEEN MUCH FOG YET. COULD CANCEL THOSE COUNTIES AROUND SUNRISE IF THINGS DO NOT CHANGE...STILL A COUPLE OF HOURS TO GO YET. MPC/JZ && .PREV DISCUSSION ISSUED 345 AM FRI SEP 15... 03Z SURFACE/RUC ANALYSIS AND IR/WV IMAGERY SHOW A LARGE-SCALE TROUGH DIGGING OVER THE WEST COAST...AND A RELATIVELY FLATTENED RIDGE PARKED ACROSS THE MIDDLE CONUS. HIGH PRESSURE AT THE SURFACE CENTERED NE OF THE GEORGIAN BAY UNDER NORTHERLY FLOW ALOFT. THIS HIGH PRESSURE COMBINED WITH 500MB RIDGING WHOSE AXIS RUNS ALONG THE MISSISSIPPI RIVER VALLEY AND VERY DRY AIR ALOFT HAS ALLOWED FOR EXCELLENT RADIATIONAL COOLING CONDITIONS ACROSS THE CWA. THESE CONDITIONS HAVE HELPED WIDESPREAD FOG TO FORM ALREADY...MOSTLY CONFINED TO INLAND AREAS SOUTH OF M-32 AS NOTED BY OBS (ACB...3/4SM....GOV....1/2SM...HTL...1/4SM) AND 11U-3.9U SATELLITE IMAGERY. TEMPERATURES HAVE FALLEN INTO THE MIDDLE 40S TO LOWER 50S AND MOST PLACES ARE AT OR BELOW THEIR CROSSOVER TEMPS WITH THE EXCEPTION OF EASTERN UPPER. WITH NO PRECIP IN THE PICTURE UNTIL SUNDAY MORNING...MAIN FORECAST CONCERNS IN THE SHORT TERM REVOLVE AROUND FOG HEADLINES THIS MORNING. FOG HEADLINES....NOT SURPRISINGLY...FOG HAS BEEN ON THE INCREASE THIS MORNING AS TEMPS COOL. CURRENT OBS AND SATELLITE TRENDS SUPPORT KEEPING THE DENSE FOG ADVISORY GOING FOR AREAS SOUTH OF M-72. THE QUESTION IS WHETHER FOG WILL BECOME THICK ENOUGH OVER NORTHERN LOWER NORTH OF THIS LINE TO WARRANT HEADLINES? TEMPS HAVE FALLEN AT OR BELOW THE CROSSOVER TEMP FOR MANY LOCATIONS ACROSS THIS AREA BUT FOG HAS NOT FORMED NEARLY AS QUICK AS THEIR COUNTERPARTS TO THE SOUTH (07Z GLR JUST WENT 1/4SM FG BUT IS ONLY SITE NORTH OF M-72). WITH FURTHER COOLING TO TAKE PLACE THIS MORNING...EXPECT FOG TO BECOME MORE WIDESPREAD...BUT AM RELUCTANT TO CHANGE HEADLINES UNTIL MORE EVIDENCE BECOMES APPARENT FROM THE OBS. WILL HAVE TO KEEP AN EYE ON THINGS THROUGH THE EARLY MORNING HOURS. FOR THE REMAINDER OF TODAY...ANOTHER FANTASTIC DAY ON TAP...ONCE THE FOG LIFTS THIS MORNING. STRONG SUBSIDENCE AS NOTED BY THE 850-500MB RH 10 TO 20 PCT WILL PREVAIL WITH RIDGING AT THE SURFACE AND ALOFT. THIS SUBSIDENCE WILL INCREASE THROUGH THE DAY AS HEIGHT RISES TAKE PLACE WITH THE 500MB RIDGE STRENGTHENING AS IT PASSES OVERHEAD. ONCE THE FOG BURNS OFF THIS MORNING...LINGERING MOISTURE BELOW THE SUBSIDENCE INVERSION AS NOTED BY AN ACARS SOUNDING FROM APN (DEWPOINT 9C AT 925MB) LATE LAST EVENING WILL PROMOTE FLAT CU BUILD UP ESPECIALLY ACROSS THE HIGHER TERRAIN. WITH MIXING OF THE DRY AIR ABOVE...THIS CU WILL DIMINISH DURING THE MIDDLE OF THE AFTERNOON...LEAVING MOST LOCATIONS MOSTLY SUNNY. 850MB TEMPS INCREASE A DEGREE OR TWO...RANGING FROM 12-13C ACROSS NORTHERN LOWER...TO 13-14C OVER EASTERN UPPER...SO WE WILL SEE HIGHS MOSTLY IN THE MIDDLE 70S. THESE TEMPS...COMBINED WITH THE LIGHT WINDS WITH THE RIDGING...WILL PROMOTE LAKE BREEZES THIS AFTERNOON (950MB WINDS 5-10KTS NORTHERN LOWER AND 10-15KTS EASTERN UPPER)...AND WILL KEEP AREAS NEAR THE LAKES A FEW DEGREES COOLER. MPC LATER PERIODS...UPPER RIDGE AXIS WILL GRADUALLY SLIDE FROM THE CENTRAL TO THE EASTERN LAKES...AS AN IMPRESSIVE UPPER LOW GETS CARVED OUT IN THE NORTHERN PLAINS. QUIET WX LOOKS TO PREVAIL THRU SATURDAY...BUT A COLD FRONT WILL SLOWLY APPROACH FROM THE WEST FOR THE TAIL END OF THE WEEKEND. PRECIP CHANCES FROM SAT NIGHT ONWARD ARE THE MAIN CHALLENGE. MODELS...NAM IS RATHER FAST WITH THE COLD FRONT...NEARING LAKE MI BY SUNDAY MORNING. THE GFS STILL HAS THE BOUNDARY ON THE OTHER SIDE OF WI. SREF STARTS SLOW BUT ALMOST CATCHES UP WITH THE NAM...NGM (FOR WHAT IT/S WORTH) IS ALSO FAST...CANADIAN IS SLOW. NAM/GFS BOTH SHOWING GOOD CONSISTENCY. WILL LEAN TOWARD THE SLOW SIDE PER USUAL MODEL BIASES...BUT THAT STILL MEANS BRINGING IN RAIN FASTER THAN EARLIER FORECAST. TONIGHT/SATURDAY...WX CONCERNS FAIRLY MINIMAL. ANOTHER CLEAR AND STILL NIGHT TONIGHT WILL RESULT IN FOG. BUT SHOULD NOT BE AS MUCH FOG AS THIS MORNING...AFTER ANOTHER DAY OF GOOD DIURNAL MIXING AND WITH THE SURFACE HIGH MOVING EAST OF THE FORECAST AREA. WILL STAY TOWARD THE COOL END OF GUIDANCE TEMPS. MAY HAVE SOME CU/STRATOCU IN EASTERN UPPER MI SATURDAY...AS DEVELOPING SE SUB-900MB WINDS BRING IN SOME EXTRA MOISTURE OFF OF HURON. AND SOME CIRRUS WILL ARRIVE IN NORTHERN/WESTERN ZONES LATE. OTHERWISE...PLENTY OF SUNSHINE...WITH MAX TEMPS IN THE 70S...PERHAPS JUST TOUCHING 80 IN THE SOUTHERN ZONES (LIKE TVC...WHICH WILL BENEFIT FROM A DOWNSLOPING SOUTH WIND). SATURDAY NIGHT...DEVELOPING 850MB LOW LEVEL JET WILL PUNCH FROM KS INTO WI. THIS WILL BRING AN 850MB THETA-E RIDGE EAST WITH TIME...POKING INTO THE NORTHERN AND WESTERN ZONES LATE. INCREASING WARM/MOIST ADVECTION WILL SUPPORT A BAND OF SHOWERS (AND MAYBE AN EMBEDDED THUNDERSTORM) TRYING TO WORK ACROSS LAKE MI OVERNIGHT. INSTABILITY PROGS FROM EVEN THE AGGRESSIVE NAM DO NOT SUPPORT THUNDER THIS FAR EAST (ONLY 100-200 MUCAPE). BUT RAPID SATURATION OF THE MID AND LOW LEVELS AFTER 09Z MAY ALLOW SOME SHOWERS TO WORK IN FROM THE WEST. WILL HAVE A SMALL CHANCE OF PRECIP AFTER 08Z FROM CAD TO DE TOUR AND WEST. OTHERWISE...MID/HIGH CLOUDS WILL BE THICKENING EVERYWHERE...WITH DRY AIR BELOW 700MB PRECLUDING PRECIP. WILL BE A RELATIVELY WARM NIGHT WITH CLOUDS AND NO DECOUPLING...MIN TEMPS MAINLY UPPER 50S TO LOWER 60S. SUNDAY...850MB THETA-E RIDGE WILL TAKE IT/S TIME WORKING INTO AND ACROSS THE FORECAST AREA. FORCING/DYNAMICS ARE NOT ESPECIALLY IMPRESSIVE...AS THE LOW LEVEL JET DOES IT/S USUAL EARLY MORNING DECAY...AND UPSTREAM COLD FRONT WILL ONLY APPROACH LAKE MI TOWARD EVENING (AS LONG AS THE SLOWER SOLUTIONS HOLD). EXPECT A WEAKENING BAND OF SHOWERS TO PRESS FURTHER EAST IN THE MORNING BEFORE COMPLETELY FALLING APART. THEN IT FALLS TO HOW MUCH HEATING WE CAN SEE. WITH 850MB TEMPS +16/17C...MAX TEMPS WILL NEED TO BE NEAR 80 TO ALLOW SURFACE BASED INSTABILITY TO COOK OFF SOME STORMS. WE MIGHT GET THERE GIVEN THE EXPECTED MILD START TO THE DAY...BUT WITH A FAIR AMOUNT OF CLOUD COVER 80 IS PROBABLY THE TOP END. END RESULT...WILL HAVE A CHANCE OF SHRA MOST EVERYWHERE IN THE MORNING...AND ADD TSRA FOR THE AFTERNOON. WILL LEAVE PRECIP OUT NEAR SAGINAW BAY WHERE SURFACE RIDGING AND LOW LEVEL DRY AIR WILL TRY TO HANG ON THE LONGEST. REST OF THE FORECAST...WILL REMOVE THUNDER FROM EASTERN UPPER/NW LOWER MI MONDAY. COLD FRONT GOES THRU EARLY AND STRONG LOW LEVEL COLD ADVECTION IS WELL AHEAD OF THE COLD CORE ALOFT. WILL LEAVE THUNDER IN NE LOWER...THOUGH CURRENT PREFERRED TIMING SUGGEST EARLY MORNING WILL BE THE BEST SHOT THERE. WILL TREND TEMPS DOWNWARD A BIT MORE MONDAY AND ESPECIALLY TUESDAY...AS MODELS ARE CONSISTENT IN SHOWING A FAIRLY DRASTIC COLD SNAP FOR THIS TIME OF YEAR. (NOTE THE POSSIBILITY OF ACCUMULATING SNOW OVER THE WEEKEND IN THE MT/ND BORDER AREA. FOLKS...SUMMER IS ENDING.) ZOLTOWSKI && .APX...WATCHES/WARNINGS/ADVISORIES...DENSE FOG ADVISORY UNTIL 10 AM...MIZ022-025>036-041-042. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 445 AM EDT FRI SEP 15 2006 .DISCUSSION... MAIN FCST CONCERNS ARE PCPN CHANCES/TIMING THIS WEEKEND ALONG WITH TSRA POTENTIAL. WV IMAGERY AND RUC ANALYSIS INDICATED A TROF OVER THE WRN CONUS WITH A CLOSED MID/UPPER LEVEL LOW OVER THE PAC NW. DOWNSTREAM...A RDG EXTENDED FROM TX TO THE WRN GRT LAKES. AT THE SFC...A TROF WAS LOCATED FROM ERN WY INTO ERN CO WITH A FRONT FROM NE WY THROUGH ND TO SE MANITOBA WHILE A HIGH PRES PREVAILED OVER THE CNTRL GRT LAKES. THE WAA PATTERN UPSTREAM HAS BROUGHT MID/HIGH CLOUDS INTO THE ERN DAKOTAS AND UPR MS VALLEY. RADIATION FOG HAS AGAIN DEVELOPED OVER THE CNTRL AND E PORTIONS OF THE CWA WITH VSBYS BLO 1/2SM AT TIMES AT KERY/KESC/KISQ. OTHERWISE...IR LOOP INDICATED MOSTLY CLEAR SKIES ACRS UPR MI. TODAY...WITH ONLY SHALLOW LOW LVL MOISTURE...EXPECT THE PATCHY FOG TO BURN OFF EARLY...BY 13Z-14Z. THEN...WAA AND ABUNDANT SUNSHINE WITH MIXING TO 900-850 MB...PER UPSTREAM SNDGS...SHOULD BOOST TEMPS INTO THE UPPER 70S OVER THE AREA...GENERALLY IN LINE WITH GFS GUIDANCE VALUES. TONIGHT...GRADIENT WILL BE STRONG ENOUGH TO KEEP SRLY WINDS GOING AND TEMPS FROM FALLING OFF MUCH...ESPECIALLY OVER DOWNSLOPE AREAS IN THE WEST HLF OF THE CWA. SAT...MDLS SUGGEST STRONG 850 MB THETA-E ADVECTION ALONG WITH THE POTENTIAL FOR WEAK SHRTWVS IN THE SW FLOW MAY SUPPORT SOME SHRA OR ISOLD TSTMS INTO MAINLY THE W THIRD OF UPR MI. ONLY LOWER END CHANCE POPS WARRANTED...GIVEN UNCERTAINTY WITH TIMING AND STRENGTH OF THE THE SHRTWVS. SINCE THE MORE UNSTABLE AIR WILL REMAIN W OF UPR MI...STRONG OR SVR STORMS ARE NOT EXPECTED. SAT NIGHT INTO SUN...THE NAM WAS SIGNIFICANTLY FASTER WITH THE COLD FRONT. EVEN THOUGH THE 21Z SREF ALSO SUPPORTS A FASTER FRONTAL MOVEMENT...THE UKMET/ECMWF ARE MORE IN LINE WITH THE SLOWER GFS. A COMPROMISE TOWARD THE GFS WAS PREFERRED WHICH WOULD SUPPORT SHRA/TSRA CHANCES SAT NIGHT IN WAA PATTERN UPR MI NEAR THE NOSE OF 40KT H8 LLJ. SCT SHRA/TSRA SHOULD ALSO DEVELOP SUN ALONG AND AHEAD OF THE FRONT. GOOD DEEP LYR SHEAR WOULD SUPPORT POTENTIAL FOR STRONG TO SEVERE STORMS IF CLOUDS THIN OUT ENOUGH FOR DAYTIME HEATING TO BOOST INSTABILITY. MON INTO TUE...THE 00Z GFS REMAINS SLOWER AND DEEPER WITH THE MID LVL LOW MOVING THROUGH THE PLAINS TOWARD SRN CANADA COMPARED TO THE 00Z CANADIAN GLBL AND THE 12Z/14 00Z/15 ECMWF AND 00Z UKMET. THE PREFERRED FASTER SOLUTIONS...PER HPC...STILL SUGGEST THAT WRAP-AROUND MOISTURE AND PCPN WILL AFFECT UPR MI MON WITH ENOUGH COLD AIR(H8 TEMPS DOWN TO -3C)FOR LAKE EFFECT OR LAKE ENHANCED RAIN. SO...CONTINUED TO NUDGE MAX TEMPS DOWN A BIT FOR INLAND LOCATIONS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 420 AM EDT FRI SEP 15 2006 .SHORT TERM...TODAY AND TONIGHT SURFACE HIGH AND UPPER RIDGE WILL BE OVER HEAD TODAY AND TONIGHT. FORECAST PROBLEM WILL BE FOG AND CLOUD COVER THIS MORNING. LARGE SHIELD OF LOW STRATUS HAS BEEN WORKING BACK AROUND UPPER LOW SYSTEM OVER PENNSYLVANIA INTO THE EASTERN THUMB AND IS CONTINUING TO SPREAD SOUTH AND WESTWARD UNDER INVERSION. THIS IS ALSO BEING HELPED BY WEAK SURFACE TROUGHING EXTENDING BACK WEST INTO THUMB. GFS SEEMS TO HAVE THE BEST HANDLE ON THIS LOOKING AT THE 925-950MB MOISTURE FIELD. LOW CLOUDS WILL LIKELY MAKE IT NO FURTHER WEST THEN US23/US23/I75 LINE. WILL CONTINUE THE DENSE FOG ADVISORY UNTIL 14Z AS MOST OBSERVATIONS SHOWING VISIBILITIES 1/4 MILE OR LESS...EXCEPTIONS HAVE BEEN MOST OF WAYNE COUNTY WHERE URBAN HEAT ISLAND AFFECT SEEMS TO HAVE KEPT DEW POINT SPREAD APART FAR ENOUGH TO LIMIT FOG DEVELOPMENT SO FAR AND EASTERN MACOMB COUNTY WHERE CLOUD COVER HAS PREVENT DECENT RADIATIONAL COOLING. STILL SEVERAL HOURS TO GO BEFORE SUNRISE SO DO EXPECT SOME DEGREE OF FOG TO DEVELOP IN THESE AREAS BUT MORE OF PATCHY DENSE FOG THEN WIDESPREAD. FOG AND CLOUDS WILL MIX AND DISSIPATE OUT BY NOON. MODEL SOUNDINGS SHOW ENOUGH INSTABILITY AND LOW LEVEL MOISTURE ACROSS EASTERN PORTIONS OF CWA TO GENERATE SCT-BKN CU THIS AFTERNOON SO WILL CARRY PARTLY CLOUDY THOSE AREAS AND MOSTLY SUNNY ELSEWHERE. SHOULD HAVE CLEAR SKIES TONIGHT WITH OUT ANY LOW LEVEL CLOUD INTRUSION LIKE OVERNIGHT. EXPECT GOOD RADIATIONAL COOLING AGAIN TONIGHT SO WILL CARRY AREAS OF FOG. NOT EXPECTING WIDESPREAD DENSE FOG BUT WILL LIKELY SEE PATCHY DENSE FOG. WILL GO WITH WARMER GFS NUMBERS AS MET GUIDANCE UNDER DID YESTERDAYS HIGHS AND SEEMS A BIT LOW FOR TODAY. && .LONG TERM...SATURDAY THROUGH THURSDAY A BRIEF WARM UP THEN AUTUMN CONDITIONS SETTLE INTO THE GREAT LAKES FOR NEXT WEEK (BUT NOT AS EMPHATIC PER THE GFS). LARGE SCALE PATTERN SHIFT IS UNDERWAY WITH DEEP AND COLD TROUGH ACROSS THE PACIFIC NORTHWEST INTO THE FOUR CORNERS REGION AND SURFACE LEE-CYCLOGENESIS ACROSS THE WESTERN DAKOTAS. IN TURN THE DOWNSTREAM RIDGE CONTINUES TO AMPLIFY WITH STRENGTHENING SURFACE HIGH ACROSS THE MIDWEST AND TENNESSEE VALLEY THAT WILL REMAIN IN PLACE THROUGH SATURDAY. MODELS ARE CONSISTENT WITH OCCLUDED FRONT IN THE GREAT LAKES SUNDAY NIGHT INTO MONDAY MORNING. THE NMM/CANADIAN SUGGEST 500MB WAVE ON THE ENTRANCE SIDE OF THE JET WILL AMPLIFY AND TRACK INTO THE STATE LATE SUNDAY BUT CONSENSUS FROM THE GFS/ECMWF SUGGEST HOLDING OFF UNTIL SUNDAY NIGHT GIVEN STRENGTH OF UPSTREAM TROUGH AND TRENDS SUGGEST A LITTLE SLOWER PROGRESS. THIS CONTINUES WITH THE CHANCE FOR SHOWERS/THUNDERSTORMS SUNDAY NIGHT INTO MONDAY MORNING AND WE WILL RAISE POPS A LITTLE MORE. DEEP THETA-E ADVECTION ALONG WITH 30-40KTS LOW LEVEL JET SUPPORTS THE HIGHER PROBABILITIES AND WITH ENTRANCE REGION DYNAMICS TO AID IN ADDITIONAL LIFT. TEMPERATURES WILL BE MILD FOR THIS TIME OF THE YEAR WITH THE OFFICIAL START TO AUTUMN THIS WEEKEND. NOT TO WORRY AS THE CALENDAR WILL CATCH UP QUICKLY EARLY NEXT WEEK WITH FROPA EXPECTED BY MONDAY AFTERNOON AND COLD ADVECTION TO PERUSE. THE GFS SEEMS TO BE OVERDEVELOPED WITH THE CLOSED 500MB LOW AND WE PREFER THE MORE OPEN NATURE SIMILAR TO THE ECMWF/CANADIAN. THIS SHOULD KEEP THOSE NEGATIVE 850MB TEMPS A BIT IN CHECK (FOR NOW) ACROSS THE STATE BUT NEVERTHELESS LOWER SINGLE DIGIT READINGS EMBEDDED WITHIN THE CYCLONIC FLOW WILL PROVIDE UNSETTLED CONDITIONS THROUGH MID-WEEK WITH THE CHANCE FOR RAIN SHOWERS AND SOME LAKE EFFECT RAIN SHOWERS FROM LAKE MICHIGAN. THEN FOLLOWING THE ECMWF/CANADIAN IDEA OF BUILDING HEIGHTS AND SURFACE PRESSURES TOWARD THE END OF THE WEEK ACROSS THE NORTHERN PLAINS AND EVENTUALLY INTO THE GREAT LAKES REGION. HOWEVER...THIS WILL NOT BE A CLEAN FORECAST AS INDICATIONS ARE WE QUICKLY TRANSITION INTO A ZONAL FLOW WITH A FURTHER SOUTH POSITION OF THE MAIN UPPER JET. LIKELY SEE MORE CLOUDS BUT WILL REFRAIN FROM THE MENTION OF PRECIP AT THIS TIME. SUMMER IS INDEED COMING TO AN END. && .PREV DISCUSSION...ISSUED 100 AM EDT FRI SEP 15 2006 AVIATION... REDUCED VISIBILITIES IN FOG WILL BE A BIG AVIATION CONCERN THIS MORNING AS HIGH PRESSURE REMAINS CENTERED OVER THE STATE. CLEAR SKIES...LIGHT WINDS AND HIGH SOIL MOISTURE HAS SET THE STAGE FOR OPTIMAL RADIATIONAL FOG DEVELOPMENT THIS MORNING. WILL CONTINUE TO CARRY SEVERAL HOURS OF QUARTER MILE VISIBILITY AT FNT AND MBS. THE COMBINATION OF THE URBAN HEAT ISLAND AFFECT AND A LITTLE STRONGER NORTHERLY WINDS JUST ATOP THE NOCTURNAL INVERSION MAY BE ENOUGH TO PREVENT DENSE FOG AT DTW AND DET. AS OF 04Z...THERE IS A SOLID STRATUS DECK BASED AROUND 1200FT MOVING INTO MACOMB COUNTY. THE 00Z RUC NOW HAS THE BEST HANDLE ON THIS CLOUD COVER...WHICH BRINGS IT INTO DET BY 07Z. THE RUC DOES NOT SUGGEST MUCH ADDITIONAL WESTWARD MOVEMENT TO CLOUDS WITH THE LOW LEVEL WINDS FORECAST TO BE MORE NORTHERLY AT DETROIT. AT THIS POINT...WILL BRING THE STRATUS DECK INTO DET BUT HOLD OFF AT DTW. THE AFFECT OF THIS STRATUS DECK WILL BE TO REDUCE THE FOG DEVELOPMENT AND ALLOW SURFACE VISIBILITY TO INCREASE. BASED ON OBS IN WISCONSIN YESTERDAY AND GIVEN THE LOWER MID SEPTEMBER SUN ANGLE...FOG SHOULD NOT MIX OUT UNTIL 13-15Z. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...DENSE FOG ADVISORY...MIZ047-MIZ048-MIZ049-MIZ053-MIZ054-MIZ055- MIZ060-MIZ061-MIZ062-MIZ063-MIZ068-MIZ069-MIZ070-MIZ075- MIZ076-MIZ082-MIZ083 UNTIL 10 AM FRIDAY. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...DRC LONG TERM....BGM 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 GAYLORD MI 345 AM EDT FRI SEP 15 2006 .DISCUSSION...03Z SURFACE/RUC ANALYSIS AND IR/WV IMAGERY SHOW A LARGE-SCALE TROUGH DIGGING OVER THE WEST COAST...AND A RELATIVELY FLATTENED RIDGE PARKED ACROSS THE MIDDLE CONUS. HIGH PRESSURE AT THE SURFACE CENTERED NE OF THE GEORGIAN BAY UNDER NORTHERLY FLOW ALOFT. THIS HIGH PRESSURE COMBINED WITH 500MB RIDGING WHOSE AXIS RUNS ALONG THE MISSISSIPPI RIVER VALLEY AND VERY DRY AIR ALOFT HAS ALLOWED FOR EXCELLENT RADIATIONAL COOLING CONDITIONS ACROSS THE CWA. THESE CONDITIONS HAVE HELPED WIDESPREAD FOG TO FORM ALREADY...MOSTLY CONFINED TO INLAND AREAS SOUTH OF M-32 AS NOTED BY OBS (ACB...3/4SM....GOV....1/2SM...HTL...1/4SM) AND 11U-3.9U SATELLITE IMAGERY. TEMPERATURES HAVE FALLEN INTO THE MIDDLE 40S TO LOWER 50S AND MOST PLACES ARE AT OR BELOW THEIR CROSSOVER TEMPS WITH THE EXCEPTION OF EASTERN UPPER. WITH NO PRECIP IN THE PICTURE UNTIL SUNDAY MORNING...MAIN FORECAST CONCERNS IN THE SHORT TERM REVOLVE AROUND FOG HEADLINES THIS MORNING. FOG HEADLINES....NOT SURPRISINGLY...FOG HAS BEEN ON THE INCREASE THIS MORNING AS TEMPS COOL. CURRENT OBS AND SATELLITE TRENDS SUPPORT KEEPING THE DENSE FOG ADVISORY GOING FOR AREAS SOUTH OF M-72. THE QUESTION IS WHETHER FOG WILL BECOME THICK ENOUGH OVER NORTHERN LOWER NORTH OF THIS LINE TO WARRANT HEADLINES? TEMPS HAVE FALLEN AT OR BELOW THE CROSSOVER TEMP FOR MANY LOCATIONS ACROSS THIS AREA BUT FOG HAS NOT FORMED NEARLY AS QUICK AS THEIR COUNTERPARTS TO THE SOUTH (07Z GLR JUST WENT 1/4SM FG BUT IS ONLY SITE NORTH OF M-72). WITH FURTHER COOLING TO TAKE PLACE THIS MORNING...EXPECT FOG TO BECOME MORE WIDESPREAD...BUT AM RELUCTANT TO CHANGE HEADLINES UNTIL MORE EVIDENCE BECOMES APPARENT FROM THE OBS. WILL HAVE TO KEEP AN EYE ON THINGS THROUGH THE EARLY MORNING HOURS. FOR THE REMAINDER OF TODAY...ANOTHER FANTASTIC DAY ON TAP...ONCE THE FOG LIFTS THIS MORNING. STRONG SUBSIDENCE AS NOTED BY THE 850-500MB RH 10 TO 20 PCT WILL PREVAIL WITH RIDGING AT THE SURFACE AND ALOFT. THIS SUBSIDENCE WILL INCREASE THROUGH THE DAY AS HEIGHT RISES TAKE PLACE WITH THE 500MB RIDGE STRENGTHENING AS IT PASSES OVERHEAD. ONCE THE FOG BURNS OFF THIS MORNING...LINGERING MOISTURE BELOW THE SUBSIDENCE INVERSION AS NOTED BY AN ACARS SOUNDING FROM APN (DEWPOINT 9C AT 925MB) LATE LAST EVENING WILL PROMOTE FLAT CU BUILD UP ESPECIALLY ACROSS THE HIGHER TERRAIN. WITH MIXING OF THE DRY AIR ABOVE...THIS CU WILL DIMINISH DURING THE MIDDLE OF THE AFTERNOON...LEAVING MOST LOCATIONS MOSTLY SUNNY. 850MB TEMPS INCREASE A DEGREE OR TWO...RANGING FROM 12-13C ACROSS NORTHERN LOWER...TO 13-14C OVER EASTERN UPPER...SO WE WILL SEE HIGHS MOSTLY IN THE MIDDLE 70S. THESE TEMPS...COMBINED WITH THE LIGHT WINDS WITH THE RIDGING...WILL PROMOTE LAKE BREEZES THIS AFTERNOON (950MB WINDS 5-10KTS NORTHERN LOWER AND 10-15KTS EASTERN UPPER)...AND WILL KEEP AREAS NEAR THE LAKES A FEW DEGREES COOLER. MPC LATER PERIODS...UPPER RIDGE AXIS WILL GRADUALLY SLIDE FROM THE CENTRAL TO THE EASTERN LAKES...AS AN IMPRESSIVE UPPER LOW GETS CARVED OUT IN THE NORTHERN PLAINS. QUIET WX LOOKS TO PREVAIL THRU SATURDAY...BUT A COLD FRONT WILL SLOWLY APPROACH FROM THE WEST FOR THE TAIL END OF THE WEEKEND. PRECIP CHANCES FROM SAT NIGHT ONWARD ARE THE MAIN CHALLENGE. MODELS...NAM IS RATHER FAST WITH THE COLD FRONT...NEARING LAKE MI BY SUNDAY MORNING. THE GFS STILL HAS THE BOUNDARY ON THE OTHER SIDE OF WI. SREF STARTS SLOW BUT ALMOST CATCHES UP WITH THE NAM...NGM (FOR WHAT IT/S WORTH) IS ALSO FAST...CANADIAN IS SLOW. NAM/GFS BOTH SHOWING GOOD CONSISTENCY. WILL LEAN TOWARD THE SLOW SIDE PER USUAL MODEL BIASES...BUT THAT STILL MEANS BRINGING IN RAIN FASTER THAN EARLIER FORECAST. TONIGHT/SATURDAY...WX CONCERNS FAIRLY MINIMAL. ANOTHER CLEAR AND STILL NIGHT TONIGHT WILL RESULT IN FOG. BUT SHOULD NOT BE AS MUCH FOG AS THIS MORNING...AFTER ANOTHER DAY OF GOOD DIURNAL MIXING AND WITH THE SURFACE HIGH MOVING EAST OF THE FORECAST AREA. WILL STAY TOWARD THE COOL END OF GUIDANCE TEMPS. MAY HAVE SOME CU/STRATOCU IN EASTERN UPPER MI SATURDAY...AS DEVELOPING SE SUB-900MB WINDS BRING IN SOME EXTRA MOISTURE OFF OF HURON. AND SOME CIRRUS WILL ARRIVE IN NORTHERN/WESTERN ZONES LATE. OTHERWISE...PLENTY OF SUNSHINE...WITH MAX TEMPS IN THE 70S...PERHAPS JUST TOUCHING 80 IN THE SOUTHERN ZONES (LIKE TVC...WHICH WILL BENEFIT FROM A DOWNSLOPING SOUTH WIND). SATURDAY NIGHT...DEVELOPING 850MB LOW LEVEL JET WILL PUNCH FROM KS INTO WI. THIS WILL BRING AN 850MB THETA-E RIDGE EAST WITH TIME...POKING INTO THE NORTHERN AND WESTERN ZONES LATE. INCREASING WARM/MOIST ADVECTION WILL SUPPORT A BAND OF SHOWERS (AND MAYBE AN EMBEDDED THUNDERSTORM) TRYING TO WORK ACROSS LAKE MI OVERNIGHT. INSTABILITY PROGS FROM EVEN THE AGGRESSIVE NAM DO NOT SUPPORT THUNDER THIS FAR EAST (ONLY 100-200 MUCAPE). BUT RAPID SATURATION OF THE MID AND LOW LEVELS AFTER 09Z MAY ALLOW SOME SHOWERS TO WORK IN FROM THE WEST. WILL HAVE A SMALL CHANCE OF PRECIP AFTER 08Z FROM CAD TO DE TOUR AND WEST. OTHERWISE...MID/HIGH CLOUDS WILL BE THICKENING EVERYWHERE...WITH DRY AIR BELOW 700MB PRECLUDING PRECIP. WILL BE A RELATIVELY WARM NIGHT WITH CLOUDS AND NO DECOUPLING...MIN TEMPS MAINLY UPPER 50S TO LOWER 60S. SUNDAY...850MB THETA-E RIDGE WILL TAKE IT/S TIME WORKING INTO AND ACROSS THE FORECAST AREA. FORCING/DYNAMICS ARE NOT ESPECIALLY IMPRESSIVE...AS THE LOW LEVEL JET DOES IT/S USUAL EARLY MORNING DECAY...AND UPSTREAM COLD FRONT WILL ONLY APPROACH LAKE MI TOWARD EVENING (AS LONG AS THE SLOWER SOLUTIONS HOLD). EXPECT A WEAKENING BAND OF SHOWERS TO PRESS FURTHER EAST IN THE MORNING BEFORE COMPLETELY FALLING APART. THEN IT FALLS TO HOW MUCH HEATING WE CAN SEE. WITH 850MB TEMPS +16/17C...MAX TEMPS WILL NEED TO BE NEAR 80 TO ALLOW SURFACE BASED INSTABILITY TO COOK OFF SOME STORMS. WE MIGHT GET THERE GIVEN THE EXPECTED MILD START TO THE DAY...BUT WITH A FAIR AMOUNT OF CLOUD COVER 80 IS PROBABLY THE TOP END. END RESULT...WILL HAVE A CHANCE OF SHRA MOST EVERYWHERE IN THE MORNING...AND ADD TSRA FOR THE AFTERNOON. WILL LEAVE PRECIP OUT NEAR SAGINAW BAY WHERE SURFACE RIDGING AND LOW LEVEL DRY AIR WILL TRY TO HANG ON THE LONGEST. REST OF THE FORECAST...WILL REMOVE THUNDER FROM EASTERN UPPER/NW LOWER MI MONDAY. COLD FRONT GOES THRU EARLY AND STRONG LOW LEVEL COLD ADVECTION IS WELL AHEAD OF THE COLD CORE ALOFT. WILL LEAVE THUNDER IN NE LOWER...THOUGH CURRENT PREFERRED TIMING SUGGEST EARLY MORNING WILL BE THE BEST SHOT THERE. WILL TREND TEMPS DOWNWARD A BIT MORE MONDAY AND ESPECIALLY TUESDAY...AS MODELS ARE CONSISTENT IN SHOWING A FAIRLY DRASTIC COLD SNAP FOR THIS TIME OF YEAR. (NOTE THE POSSIBILITY OF ACCUMULATING SNOW OVER THE WEEKEND IN THE MT/ND BORDER AREA. FOLKS...SUMMER IS ENDING.) ZOLTOWSKI && .APX...WATCHES/WARNINGS/ADVISORIES...DENSE FOG ADVISORY ALONG AND SOUTH OF M-72...UNTIL 10 AM. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 100 AM EDT FRI SEP 15 2006 .AVIATION... REDUCED VISIBILITIES IN FOG WILL BE A BIG AVIATION CONCERN THIS MORNING AS HIGH PRESSURE REMAINS CENTERED OVER THE STATE. CLEAR SKIES...LIGHT WINDS AND HIGH SOIL MOISTURE HAS SET THE STAGE FOR OPTIMAL RADIATIONAL FOG DEVELOPMENT THIS MORNING. WILL CONTINUE TO CARRY SEVERAL HOURS OF QUARTER MILE VISIBILITY AT FNT AND MBS. THE COMBINATION OF THE URBAN HEAT ISLAND AFFECT AND A LITTLE STRONGER NORTHERLY WINDS JUST ATOP THE NOCTURNAL INVERSION MAY BE ENOUGH TO PREVENT DENSE FOG AT DTW AND DET. AS OF 04Z...THERE IS A SOLID STRATUS DECK BASED AROUND 1200FT MOVING INTO MACOMB COUNTY. THE 00Z RUC NOW HAS THE BEST HANDLE ON THIS CLOUD COVER...WHICH BRINGS IT INTO DET BY 07Z. THE RUC DOES NOT SUGGEST MUCH ADDITIONAL WESTWARD MOVEMENT TO CLOUDS WITH THE LOW LEVEL WINDS FORECAST TO BE MORE NORTHERLY AT DETROIT. AT THIS POINT...WILL BRING THE STRATUS DECK INTO DET BUT HOLD OFF AT DTW. THE AFFECT OF THIS STRATUS DECK WILL BE TO REDUCE THE FOG DEVELOPMENT AND ALLOW SURFACE VISIBILITY TO INCREASE. && BASED ON OBS IN WISCONSIN YESTERDAY AND GIVEN THE LOWER MID SEPTEMBER SUN ANGLE...FOG SHOULD NOT MIX OUT UNTIL 13-15Z. .PREV DISCUSSION...1001 PM EDT THU SEP 14 2006 UPDATE... FOG IS ALREADY DEVELOPING ACROSS THE SAGINAW VALLEY AND THUMB UNDER CLEAR SKIES. SURFACE HIGH PRESSURE WILL BE ANCHORED OVER LOWER MICHIGAN THROUGH THE NIGHT. CLEAR SKIES...LIGHT WINDS AND AMPLE MOISTURE IN THE LOWEST 2000 FT NEAR THE SURFACE...SUPPORTED BY THE 00Z DTX SOUNDING...WILL LEAD TO THE DEVELOPMENT OF WIDESPREAD DENSE FOG. THE 00Z DTX SOUNDING DID SHOW A STRONG INVERSION NEAR 5K FT. DESPITE THIS INVERSION...DRY AIR ADVECTION NEAR THIS LEVEL IS ALLOWING THE CLOUDS ACROSS THE SOUTHERN PORTIONS OF THE FORECAST AREA TO DIMINISH RATHER QUICKLY. THERE IS ALSO A LOW STRATUS DECK OVER SOUTHERN LAKE HURON. THE 12KM NAM HAS A REASONABLE HANDLE ON THIS STRATUS DECK AND ESSENTIALLY SUGGESTS THE CLOUDS WILL NOT MAKE MUCH ADDITIONAL PROGRESS WEST INTO THE FORECAST AREA. THEREFORE A DENSE FOG ADVISORY HAS BEEN ISSUED FOR THE ENTIRE FORECAST AREA THROUGH 10 AM FRI MORNING. THE URBAN HEAT ISLAND AFFECT AND A LITTLE STRONGER WINDS FORECAST ATOP THE NOCTURNAL INVERSION MAY LIMIT THE DURATION OF THE DENSE FOG WITHIN THE CITY OF DETROIT AND INNER SUBURBS TO A BRIEF PERIOD AROUND SUNRISE. PREV DISCUSSION...ISSUED 344 PM EDT THU SEP 14 2006 SHORT TERM...TONIGHT AND FRIDAY 12Z RAOBS/WATER VAPOR LOOP SHOW THE UPPER LOW DOWNSTREAM OVER THE LOWER GREAT LAKES...WITH A RIDGE BUILDING IN ACROSS THE CENTRAL CONUS. SURFACE ANALYSIS SHOWS HIGH PRESSURE ALONG THE MISSISSIPPI VALLEY TO THE CENTRAL GREAT LAKES. VIS SATELLITE SHOWS A HEALTHY MVFR/VFR CLOUD FIELD...BEGINNING TO MIX OUT ACROSS NORTHERN LOWER AND THE THUMB BUT HOLDING FAST ACROSS THE WESTERN AND SOUTHERN CWA. 18Z/19Z TAMDAR SOUNDINGS SHOW A DECENT AMOUNT OF LOW-LEVEL MOISTURE ACROSS NORTHERN LOWER...MORE THAN 15Z RUC/12Z NAM WOULD INDICATE. CLOUDS ACROSS THE THUMB HAVE MIXED INTO A DIURNAL CU DECK WHICH WILL DISSIPATE BEFORE SUNSET...WHILE THE THICKER STRATOCU DECK ACROSS THE THE SOUTHERN AND WESTERN CWA MAY LINGER LONGER INTO THE EVENING. STILL EXPECT SKIES TO CLEAR OUT OVERNIGHT...BUT WILL INCREASE CLOUD COVER THROUGH THE EVENING. THIS MAY HAVE SOME IMPACT ON DENSE FOG POTENTIAL TONIGHT. SURFACE RIDGE WILL BUILD ACROSS LOWER MICHIGAN BY 12Z FRIDAY...WITH NEARLY CALM WINDS ACROSS THE CWA. NAM/GFS BOTH SHOW GOOD LOW-LEVEL MOISTURE...INCLUDING SURFACE CONDENSATION PRESSURE DEFICITS BELOW 10MB. THERE WAS PRETTY WIDESPREAD FOG WITH VISIBILITIES 1/4SM OR BELOW UNDER THE RIDGE AXIS UPSTREAM ACROSS WISCONSIN THIS MORNING...AS WELL AS SOME FOG REPORTS ACROSS NORTHERN ONTARIO WHERE OUR AIRMASS WILL ORIGINATE ON DIMINISHING NORTHERLY WINDS. WILL ADD AREAS OF DENSE FOG TO THE FORECAST OVERNIGHT INTO FRIDAY MORNING. WAS ON THE FENCE ABOUT A DENSE FOG ADVISORY AT THIS POINT...AND DECIDED TO HOLD OFF GIVEN UNCERTAINTY AS TO HOW QUICKLY CLOUDS WILL CLEAR OUT THIS EVENING...AS WELL AS HOW LOWER DEWPOINTS WILL MIX DOWN ACROSS NORTHERN LOWER AS THE NORTHERN CLOUDS DISSIPATE. LOWS IN THE UPPER 40S LOOK GOOD...WITH LOWER 50S ACROSS THE SOUTHERN CWA WITH THE MORE PERSISTENT CLOUD COVER. UPPER RIDGE AXIS BUILDS ACROSS LOWER MICHIGAN ON FRIDAY...WITH THE SURFACE HIGH SHIFTING DOWNSTREAM TO SOUTHEAST ONTARIO. RETURN FLOW WILL REMAIN PRETTY WEAK BEHIND THE HIGH...AT LEAST THROUGH THE DAY. EVEN WITH FULL SUN...GFS LOOKS TOO WARM WITH REMNANT THERMAL TROUGH LINGERING OVER THE REGION. WILL DROP HIGH TEMPERATURES A FEW DEGREES...GENERALLY INTO THE MID 70S FOR FRIDAY. 19Z READINGS THIS AFTERNOON ACROSS WISCONSIN WERE ONLY AROUND 70 TO THE LOW 70S. LONG TERM...FRIDAY NIGHT THROUGH THURSDAY WILL MAINTAIN THE CURRENT FORECAST FOR THE MOST PART AS MODELS STILL SUGGEST A WARMUP THROUGH SUNDAY AS UPPER RIDGE AMPLIFIES TO THE EAST OF A DEVELOPING TROUGH OVER THE PACIFIC NORTHWEST & NORTHERN PLAINS. WILL ALSO KEEP THE DRY FORECAST THROUGH SUNDAY IN THIS PATTERN. AS UPPER LOW SPINS UP OVER THE NORTHERN PLAINS WITH THIS TROUGH ON SUNDAY/SUNDAY NIGHT...MODELS STILL SUGGEST AN OCCLUDED COLD FRONT WILL SHIFT INTO LOWER MICHIGAN LATE SUNDAY NIGHT AND PROGRESS TO THE EAST OF THE AREA BY MIDDAY MONDAY. THIS SUPPORTS THE 40% CHANCE OF SHOWERS/THUNDERSTORMS SUNDAY NIGHT INTO MONDAY. THEREAFTER...SHOWERY WEATHER BECOMES ESTABLISHED IN COLD WEST FLOW OVER THE RELATIVELY WARM WATERS OF LAKE MICHIGAN. WILL BRING THESE SHOWERS INTO THE FORECAST MONDAY NIGHT AND SLOWLY TAPER THEM BACK BY WEDNESDAY NIGHT...BASICALLY TRIMMING AWAY THE SOUTHERN EXTENT DURING THE TIMEFRAME. TEMPERATURES WILL BE DECIDEDLY COOLER NEXT WEEK...AS COMPARED TO THE WEEKEND. MONDAY WILL BE THE TRANSITION DAY AS THE FRONT PROGRESSES THROUGH THE AREA. EXPECT HIGHS IN THE LOWER 70S. HIGHS WILL BE IN THE LOWER 60S TUESDAY/WEDNESDAY IN THE CORE OF THIS COMING COOL AIR WITH A SLIGHT MODIFICATION BY THURSDAY. LOWS WILL HOLD PRETTY MUCH IN THE 40S THROUGH THIS TIMEFRAME AS CLOUDS AND A STEADY WEST WIND ACT TO MODERATE THE NIGHTTIME COOLING. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...DENSE FOG ADVISORY...ALL SOUTHEAST MICHIGAN...MIDNIGHT UNTIL 10 AM. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...BRAVENDER LONG TERM....DG AVIATION/UPDATE...CONSIDINE 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 GRAND FORKS ND 441 AM CDT FRI SEP 15 2006 .SHORT TERM...SURFACE FRONT CURRENTLY EXTENDS SOUTHWEST TO NORTHEAST NEAR BIS/DVL/HCO. IT WILL BE DRIVEN INTO CANADA AGAIN TODAY DUE IN PART TO STRONG SOUTH WINDS WHICH WILL MIX TO THE SURFACE. A BI- MODAL SHORTWAVE WILL ARRIVE TODAY OVER THE REGION...THE EARLY AXIS ARRIVES ABOUT 18Z THEN ANOTHER LATE IN THE DAY. NAM SHOWS THIS SECOND ONE PRECEDED BY A 50-55 KNOT 850 MB JET ORIENTATED STRAIGHT UP THE UPPER RED RIVER VALLEY...AND BOUNDARY LAYER IS EXPECTED TO BE FAIRLY WELL MIXED TO THAT LEVEL. MVX/ABR VWP PROFILERS CURRENTLY SHOW 45-50 KNOTS AT 3-4 KFT WHICH IS CONSISTENT WITH RUC MODEL. WOULD GUESS GFS/UKMET 850 MB WINDS ARE AGAIN UNDERDONE LATER TODAY WITH AROUND 40 KNOTS. SO ISSUED THE WIND ADVISORY FOR THE AFTERNOON AND EVENING. THINK IT WILL DROP AFTER DARK SLIGHTLY LATER DUE TO SUCH DEEP MIXING AND PERSISTENT SPEEDS. THIS JET AND THE SHORTWAVE MAY ALSO BE RESPONSIBLE FOR THE INITIAL BAND OF THUNDERSTORMS TO PASS BY PROBABLY IN EARLY EVENING. BUT DO NOT EXPECT SEVERE AS ANY SCENARIO LEADING TO THAT MUCH BUOYANCY APPEARS TO BE A STRETCH. SATURDAY IS THE MOST LIKELY DAY FOR SEVERE AS DYNAMICS COME TOGETHER. A STRONG THERMAL GRADIENT WILL LIE ACROSS THE NORTH- SOUTH FRONT AS A 100+ KNOT UPPER JET APPROACHES LATE WITH CWA IN ITS LEFT/FRONT QUAD. INSTABILITY IS STILL QUESTIONABLE AND HELD OFF IN MENTIONING SEVERE STORMS IN ZONES. FEW CHANGES NECESSARY TO PRECIPITATION GRIDS EXCEPT REMOVED MENTION OF SNOW FOR SUNDAY NIGHT. GFS HAS BEEN PROGRESSING SLIGHTLY WARMER/WETTER AS THAT TIME APPROACHES. WET BULB TEMPERATURES LOOK MUCH TOO HIGH TO GET ENOUGH COOLING FOR SNOW. USER REQUESTED RED FLAG WARNING AGAIN RETAINED AS FUELS CONTINUE DRY AND WINDS WILL BE A PROBLEM TODAY. .LONG TERM...THE UPPER LOW WILL WOBBLE A BIT AS IT MOVES ACROSS ND/MN ESPECIALLY ON SUNDAY. BUT THIS IS ONLY LONG ENOUGH FOR THE UPPER JET TO PROGRESS FAR ENOUGH EAST TO GIVE THE LOW A TUG. && .AVIATION...LOW LEVEL WIND SHEAR AGAIN A PROBLEM THIS MORNING. THE WINDS WILL MIX TO THE SURFACE THIS MORNING. THINK CURRENT WIND SPEEDS IN TAFS ARE ON TRACK AND WILL MAKE LITTLE CHANGE IN UPCOMING ROUTINE ISSUANCES. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...WIND ADVISORY FROM NOON TODAY TO 10 PM CDT THIS EVENING FOR NDZ007-NDZ008-NDZ014-NDZ015-NDZ016-NDZ024-NDZ026-NDZ027- NDZ028-NDZ029-NDZ030-NDZ038-NDZ039-NDZ049-NDZ052-NDZ053- NDZ054. MN...WIND ADVISORY FROM NOON TODAY TO 10 PM CDT THIS EVENING FOR MNZ001-MNZ002-MNZ003-MNZ004-MNZ007-MNZ013-MNZ014-MNZ015- MNZ022-MNZ027-MNZ028-MNZ029-MNZ030-MNZ031-MNZ040. RED FLAG WARNING FROM 10 AM THIS MORNING TO 8 PM CDT THIS EVENING FOR MNZ001-MNZ002-MNZ003-MNZ004-MNZ005-MNZ006- MNZ007-MNZ008-MNZ009-MNZ013-MNZ014-MNZ015-MNZ016-MNZ017- MNZ022-MNZ023-MNZ024-MNZ027-MNZ028-MNZ029-MNZ030-MNZ031- MNZ032-MNZ040. && $$ GV nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 320 AM CDT FRI SEP 15 2006 .SHORT TERM...TODAY THROUGH SUNDAY NIGHT PRECIPITATION CHANCES THROUGHOUT AND WINDS TODAY WILL BE THE MAIN FOCUS FOR THE SHORT TERM FORECAST. UPPER LEVEL LOW CURRENTLY SPINNING OVER THE PAC NW WILL CONTINUE TO BE THE MAIN FEATURE OF NOTE...SLOWLY PROGRESSING INTO THE NORTHERN PLAINS THROUGH THE WEEKEND. A SERIES OF SHORTWAVES WILL EJECT OUT OF THE BASE OF THE TROUGH...AND PUSH THROUGH THE REGION TODAY INTO TONIGHT BEFORE THE MAIN TROUGH MAKES ITS WAY INTO THE NORTHERN PLAINS LATER SAT INTO SUN. FIRST SHORTWAVE IS BRINGING SOME HIGH CLOUDS TO MUCH OF THE REGION...WITH SOME VERY ISOLATED SHOWERS OVER CENTRAL NEBRASKA. THIS WAVE LIFTS THROUGH THE EASTERN CWA THIS MORNING...WITH A SECOND WAVE PUSHING INTO CENTRAL SD BY 00Z FRIDAY. THE STRONG SOUTHERLY FLOW AHEAD OF THE SYSTEM WILL CONTINUE TO PUMP ADDED MOISTURE AND WARM AIR AND THEREFORE COULD SEE SOME CHANCES FOR -TRW WITH EACH WAVE PASSING THROUGH. ALTHOUGH CHANCES LOOK BETTER WITH THE SECOND WAVE...AS INSTABILITY IS GREATER AS NOTED IN THE NAM/GFS SOUNDINGS DUE TO SOME POSSIBLE SUNSHINE DEVELOPING ACROSS CENTRAL SD BEHIND THE INITIAL WAVE. SPC HAS GONE WITH A SLIGHT RISK IN THIS AREA...WITH A WEAK DRYLINE EXPECTED TO BE THE FOCUS FOR CONVECTIVE DEVELOPMENT THIS AFTERNOON NEAR THE CENTRAL SD...PUSHING EASTWARD OVERNIGHT. LOOKING AT WINDS TODAY...MODELS ARE SHOWING STRONGER WINDS ALOFT THAN YESTERDAY...WITH A TIGHTENED PRES GRADIENT. LATEST RUC SHOWING 50 KT AT H85 BY 18Z...WITH NEARLY 30-35KT AT 925MB. ONLY LIMITING FACTOR WILL BE THE CLOUDS IN THE AREA...BUT EXPECT SOME BREAKS IN THE CLOUDS WITH ENOUGH MIXING THAT ANTICIPATE WIND ADVISORY CRITERIA BEING MET. THEREFORE HAVE ISSUED A WIND ADVISORY FOR EASTERN TWO-THIRDS OF THE CWA...ENDING THE FURTHEST WEST PORTION EARLIER AS GREATEST WINDS ALOFT SHIFT TO THE EAST BY LATE DAY INTO THE EVENING. CHANCE FOR PRECIPITATION CONTINUES INTO SATURDAY WITH THE SFC TROUGH AXIS BECOMING SITUATED ACROSS THE EASTERN DAKOTAS...AND THE COLD FRONT MAKING ITS WAY INTO THE WESTERN CWA. BEST SHEAR...AND MOISTURE AXIS LOCATED JUST AHEAD OF THE FRONT...WITH SPC TARGETING THE EASTERN DAKOTAS FOR A SLIGHT RISK SATURDAY. EXPECT THE CHANCE FOR THUNDERSTORMS TO DECREASE ACROSS THE EAST INTO SATURDAY NIGHT AS THE COLD FRONT PROGRESSES EASTWARD. NAM/GFS BOTH INDICATING DEVELOPMENT OF A DRY SLOT BEHIND THE FRONT INTO SATURDAY NIGHT/SUNDAY ACROSS THE SOUTH CENTRAL/SOUTHEASTERN CWA...SO HAVE TAPERED BACK POPS ACCORDINGLY. OTHERWISE WRAP-AROUND PRECIPITATION AREA EXPECTED TO PUSH INTO THE AREA FROM WEST TO EAST LATER SUNDAY INTO SUNDAY NIGHT AS THE UPPER LOW BECOMES CENTERED OVER NW MN. 850MB TEMPS FALL TO BELOW 0C SUN AFTERNOON INTO SUN NIGHT...WITH 925MB TEMPS REMAINING JUST ABOVE FREEZING. ALSO MODEL SOUNDINGS CONTINUE TO SHOW SATURATION IN LAYER OF 0C TO -10C LAYER SO HAVE CONTINUED WITH ALL LIQUID PRECIPITATION CHANCES ACROSS THE CWA. .LONG TERM...MONDAY THROUGH THURSDAY THE OPERATIONAL GFS RUNS FROM BOTH 18Z AND 00Z ARE A LITTLE SLOWER WITH THE DEPARTURE OF THE UPPER LEVEL LOW TO THE EAST. THEY BOTH HAVE THE UPPER LEVEL LOW OVER NW MN/RED RIVER VALLEY BY 12Z MONDAY. OTHER MODELS...00Z NAM/00Z ECMWF/21Z SREF/18Z GFS ENSEMBLE MEAN ALL FAVOR MORE OF A PROGRESSIVE LOW...AND THE OPENING UP OF THE LOW JUST NORTH OF LAKE SUPERIOR...LIFTING NE. HAVE TRIMMED POPS SOMEWHAT ON MONDAY...ANTICIPATING THE QUICKER EXIT. THIS WOULD ALSO RESULT IN CLOUDS CLEARING EARLIER THAN THE GFS HAS IT...BUT WAS A LITTLE MORE CONSERVATIVE IN DECREASING CLOUDINESS. FREEZING TEMPERATURES WILL BE POSSIBLE MONDAY NIGHT...ESPECIALLY IN THE WEST. WITH THE GFS BEING THE OUTLIER...THE SURFACE RIDGE OF HIGH PRESSURE WILL LIKELY BE QUICKER TO MOVE INTO THE AREA THAN THE GFS HAS IT. THE 18Z GFS ENSEMBLE MEAN...HAS THE HIGH INTO CENTRAL SD INSTEAD OF WESTERN SD BY TUESDAY MORNING. AS TIMING OF HIGH AND CLOUD COVER BECOME MORE CERTAIN...TEMPERATURES COULD BE DECREASED EVEN MORE IN THE WEST AND CENTRAL FORECAST AREA. GFS ENSEMBLE MEAN HAS 0 C LINE AT 850 MB RUNNING FROM SIOUX FALLS TO PIERRE TO BUFFALO SD ON MONDAY AFTERNOON. EXPECT MID 40S TO LOWER 50S ACROSS MUCH OF THE AREA ON MONDAY. CLOUDS DECREASE EVEN MORE ON TUESDAY...WITH TEMPERATURES REBOUNDING INTO THE 50S TO LOWER 60S...AND THE SURFACE HIGH SLOWLY DRIFTING EAST ACROSS THE FORECAST AREA. FOR WEDNESDAY...THE GFS IS ADVERTISING A RATHER POTENT UPPER LEVEL WAVE PUSHING EAST-SOUTHEAST ACROSS THE REGION. THERE IS PLENTY OF SPREAD AMONGST THE MODELS AT THIS TIME. LITTLE CHANGES WERE MADE BEYOND TUESDAY. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...WIND ADVISORY FOR LATE THIS MORNING THROUGH THE AFTERNOON FOR CAMPBELL...POTTER...WALWORTH...HAND...HYDE...AND BUFFALO COUNTIES. WIND ADVISORY FOR NORTHEAST SOUTH DAKOTA FOR LATE THIS MORNING THROUGH LATE EVENING. MN...WIND ADVISORY FOR BIG STONE AND TRAVERSE COUNTIES FOR LATE THIS MORNING THROUGH LATE EVENING. && $$ ALBRECHT/KNUTSVIG sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 438 AM MDT FRI SEP 15 2006 .SHORT TERM... (TODAY AND TONIGHT) ...THUNDERSTORMS AND WINDS ARE MAIN CONCERNS... SATELLITE PICTURES SHOW A POTENT SHORTWAVE MOVING THROUGH WESTERN COLORADO AT THIS TIME...WITH THUNDERSTORMS OVER GRAND JUNCTION THIS HOUR AND OVER MUCH OF THE WESTERN SLOPE. A BIT UNUSUAL FOR THE EARLY MORNING HOURS OF MID SEPTEMBER. NOCTURNAL CONVECTION SEEMS TO BE THE RESULT OF THE LEFT FRONT EXIT REGION OF THE JET PASSING OVER THE REGION. CURRENT H3 JET AXIS IS ALONG A LINE FROM PHOENIX AZ TO TRINIDAD COLORADO...WITH RUC80 INDICATED WIND SPEEDS OF 100 KTS NEAR IT'S CORE OVER NORTH CENTRAL NEW MEXICO. JET-ENHANCED CLOUDINESS AND CONVECTION IS EVIDENT IN SATELLITE PICTURES RUNNING FROM NORTHEAST AZ ACROSS THE 4 CORNERS INTO SOUTHWEST COLORADO. AS THIS SYSTEM TRACKS ACROSS COLORADO TODAY...MOST OF THE AREA WILL SEE A CHANCE OF THUNDERSTORMS...MOST NUMEROUS WEST...LEAST NUMEROUS EAST. COVERAGE WILL BE FAIRLY WIDESPREAD ACROSS THE HIGHER TERRAIN ALONG THE CONTINENTAL DIVIDE...BUT PRETTY ISOLATED OVER THE PLAINS. COULD EVEN SEE SEVERE WEATHER OVER WESTERN PORTIONS OF THE FORECAST AREA AGAIN...WITH LARGE HAIL THE PRIMARY SEVERE THREAT. ADDITIONAL STORM THREATS WILL INCLUDE WIND GUSTS OVER 50 MPH...HEAVY RAIN...AND LIGHTNING. STORMS FARTHER EAST COULD ALSO PRODUCE THESE CONDITIONS...BUT SHOULD BE FEWER AND FARTHER BETWEEN. THE POTENTIAL FOR SOME WET SNOW ACCUMULATIONS OF AN INCH OR SO WILL CONTINUE OVER THE HIGHER TERRAIN...ABOVE 11000 TO 12000 FEET. THE OTHER CONCERN TODAY/TONIGHT IS THE WIND. MODELS CONTINUE TO TAKE THE MAIN LOW CENTER ACROSS WYOMING LATER TONIGHT/SATURDAY. THIS TRACK TYPICALLY BRINGS WINDY CONDITIONS TO COLORADO. RIGHT NOW...BEST GUESS FOR PEAK WINDS...BASED ON LATEST MODEL INDICATED WINDS/THERMODYNAMIC PROFILES IS ABOUT 60 MPH FOR THE MOUNTAINS...AND ABOUT 45 MPH FOR THE LOWER ELEVATIONS. ALTHOUGH PLACES LIKE THE MONARCH PASS SENSOR AT 12K HAVE ALREADY BEEN GUSTING TO AROUND 50 MPH THIS MORNING...PROBABLY THE BEST WINDOW FOR STRONG WINDS FOR THE HIGH COUNTRY WILL COME LATE TONIGHT...AS THE UPPER LOW CENTER MOVES INTO WYOMING. THE LOWER ELEVATIONS...ON THE OTHER HAND...MAY SEE THE STRONGEST WINDS THIS AFTERNOON AND EVENING DURING PEAK HEATING AND MIXING. TEMPERATURES TODAY WILL BE A LOT LIKE YESTERDAY...EXCEPT POSSIBLY A BIT COOLER. THIS MEANS READINGS OVER THE PLAINS WILL BE ABOVE AVERAGE AGAIN...WHILE READINGS IN THE MOUNTAINS AND HIGH VALUES WILL BE NEAR AVERAGE FOR THIS TIME OF YEAR. LW .LONG TERM... (SATURDAY THROUGH NEXT WEDNESDAY) CWFA TRANSITIONING TO A WINDIER AND DRIER PATTERN FOR THE MAJORITY OF THE REGION. LATEST LONGER TERM MODELS INDICATE THAT CLOSED UPPER LOW LOCATED OVER EASTERN IDAHO AT 12Z SATURDAY TO PUSH INTO NORTHEASTERN MINNESOTA BY 18Z MONDAY...WHILE ANOTHER CLOSED UPPER LOW PUSHES INTO NORTHERN WYOMING BY NEXT WEDNESDAY AND THEN INTO THE UPPER MIDWEST BY NEXT THURSDAY. ALSO...ANOTHER CLOSED UPPER LOW IS PROJECTED TO DROP INTO SOUTHERN CALIFORNIA BY NEXT THURSDAY. SO FOR SENSIBLE WEATHER...EXPECTING GENERALLY DRY CONDITIONS OVER THE MAJORITY OF THE CWFA FROM SATURDAY INTO NEXT WEDNESDAY WITH AN UP-TICK IN POPS BY NEXT THURSDAY. GUSTY WINDS WILL BE POSSIBLE AT TIMES...ESPECIALLY SATURDAY AND THEN AGAIN FROM NEXT TUESDAY NIGHT INTO WEDNESDAY. WARMEST TEMPERATURES BETWEEN SATURDAY AND NEXT WEDNESDAY EXPECTED TO OCCUR SATURDAY AND THEN AGAIN BY NEXT TUESDAY WITH COOLEST READINGS PROJECTED MONDAY AND NEXT WEDNESDAY. THANKS SURROUNDING OFFICES FOR COORDINATION/COLLABORATION. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 915 AM EDT FRI SEP 15 2006 .SYNOPSIS... 13Z WATER VAPOR AND RUC ANALYSIS SHOWING AN INCREASINGLY AMPLIFIED PATTERN ACROSS NORTH AMERICA. MOST PROMINENT FEATURE BEING THE LARGE CLOSED UPPER LOW CENTERED OVER EASTERN WASHINGTON AND THE ASSOCIATED H5 TROUGH NOW COVERING MUCH OF THE PACIFIC COAST AND INTER-MOUNTAIN WEST. THE AMPLIFICATION OF THIS TROUGH IS FORCING DOWNSTREAM RIDGING ACROSS THE MISSISSIPPI...OHIO AND TENNESSEE VALLEY. OTHER FEATURES OF NOTE INCLUDE A WEAK H5 CLOSED LOW SPINNING ACROSS THE NORTHEASTERN STATES WITH AN ASSOCIATED TROUGH DOWN THE EAST COAST TO OUR FORECAST AREA. AT THE SURFACE...COLD FRONT HAS STALLED TO OUR SOUTH ACROSS THE CENTRAL FLORIDA PENINSULA. BEHIND THE FRONT THE DRY AIR IS BEGINNING TO MAKE ITS PUSH INTO THE FORECAST AREA. HIGH PRESSURE NOW CENTERED WELL OFF TO THE NORTHWEST OF THE REGION WILL BE SETTLED SOUTHEAST TO PROVIDE A CALM...DRY...AND PLEASANT MID-SEPTEMBER WEEKEND TO MUCH OF THE SOUTHEAST. MORNING TALLAHASSEE SOUNDING SHOWING THE ATMOSPHERE STILL FAIRLY MOIST BELOW ABOUT 800MB. HOWEVER ABOVE THIS...THE DRY AIR HAS REALLY TAKEN HOLD WITH DEWPOINT DEPRESSIONS ON THE ORDER OF -25C TO -50C. PW VALUES ARE DOWN AROUND 1.35 INCHES (~85% OF NORMAL). THIS VALUE IS EXPECTED TO FALL THROUGH THE DAY AS THE DRIER AIR CONTINUES TO ADVECT IN. REGIONAL SOUNDING TO THE NORTH FOR KBMX AND KFFC SHOW PW VALUES DOWN AROUND 0.65". && REST OF TODAY... GOING FORECAST STILL LOOKS TO BE GENERALLY ON TRACK WITH HIGH TEMPERATURES IN THE UPPER 80S TO LOWER 90S PRETTY MUCH ACROSS THE BOARD. GOING FORECAST IS DRY FOR THE ENTIRE AREA...AND THIS IS CERTAINLY REASONABLE WITH THE EXTENT OF THE DRY AIR TRYING TO ADVECT IN. HOWEVER...WITH THE LIGHT FLOW...DO EXPECT TO SEE SOME DEGREE OF A SEA-BREEZE CIRCULATION DEVELOP AS WAS SEEN ON THURSDAY AFTERNOON. AS THIS OCCURS...CAN NOT RULE OUT A FEW VERY ISOLATED SHOWERS DOWN TOWARD GULF...SOUTHERN LIBERTY AND FRANKLIN COUNTIES. IN FACT...LOCAL WORKSTATION WRF RUNS FROM 06Z ARE SHOWING A FEW DOTS OF QPF ACROSS THE WESTERN BIG BEND DURING THE LATE AFTERNOON. IF A DECENT CU FIELD DOES APPEAR TO BE DEVELOPING BY LATE MORNING OR EARLY AFTERNOON...MAY ADD A SLIGHT CHANCE POP TO THESE AREAS DESCRIBED ABOVE...BUT WILL WAIT FOR ANOTHER FEW HOURS IN CASE THE DRY AIR ALOFT DOES INDEED WIN OUT IN THE END. ANY LIGHT SHOWERS THAT DO DEVELOP SHOULD BE BRIEF AND NOT HAVE MUCH OF AN IMPACT ON THE DAY. SHOULD BE ABLE TO MIX HIGH ENOUGH INTO THE COLUMN DURING THE AFTERNOON TO TAP SOME OF THE VERY DRY AIR ABOVE THE SURFACE. WITH THIS IN MIND...THINK WE WILL SEE DEWPOINT FALL INTO THE AT LEAST THE LOWER TO MIDDLE 60S MOST LOCATIONS AWAY FROM THE IMMEDIATE COAST. A FEW LOCATIONS ACROSS SOUTHERN AL...GA AND THE INTERIOR WESTERN PANHANDLE MAY SEE DEWPOINTS REACH THE UPPER 50S FOR A TIME DURING THE AFTERNOON AND EARLY EVENING. && .MARINE... NO CHANGES SEEN NEEDED TO THE MARINE FORECAST AT THIS TIME. MORNING OFFSHORE OBSERVATIONS SHOWING LIGHT AND VARIABLE WINDS AT 5 KNOTS OR LESS ACROSS OUR WATERS. SHOULD REMAIN A FAIRLY PLEASANT DAY FOR BOATING WITH WINDS COMING UP JUST A BIT DURING THE AFTERNOON INTO THE 5 TO 10 KNOT RANGE. && .AVIATION... AFTER A BRIEF PERIOD OF MVFR VSBY AT THE AREA TERMINALS, VFR CONDITIONS ARE EXPECTED FOR THE REST OF THE DAY. FOR THE OVERNIGHT PERIOD, WE ARE LOOKING FOR MVFR VSBY TO DEVELOP ONCE AGAIN AFTER 06Z AT ABY AND VLD. && .FIRE WEATHER... WILL BE KEEPING AN EYE ON THE OBSERVATIONS THROUGH THE DAY. DRY AIR WILL BE MIXING DOWN FROM ALOFT WITH RH VALUES FALLING INTO THE MIDDLE AND UPPER 30S ACROSS INLAND LOCATIONS BY MID AFTERNOON. IF ENOUGH DRY AIR IS TAPPED IN THIS MIXING...RH VALUES FALLING BELOW CRITICAL LEVELS FOR AN HOUR OR TWO WILL BE POSSIBLE ACROSS INLAND PORTIONS OF THE FLORIDA PANHANDLE. FIRE WX WATCH IN EFFECT FOR INLAND FLORIDA PANHANDLE AND PORTIONS OF THE BIG BEND STILL LOOKS VALID FOR SATURDAY AFTERNOON AND EVENING AS LONG DURATION OF RH VALUES BELOW CRITICAL LEVELS REMAINS LIKELY. && .PREV DISCUSSION... 220 AM EDT FRI SEP 15 2006 .SHORT TERM...TODAY THROUGH SUNDAY. THE HIGH PRESSURE SYSTEM FORM THE NORTH IS EXPECTED TO GRADUALLY FILTER IN OVER THE AREA INTO THE WEEKEND...AS THE UPPER TROUGH DEEPENS A BIT IN THE SE U.S...ALLOWING MUCH DRIER AIR TO FILTER IN OVER THE AREA. THEN AS THE TROUGH MOVES OFF THE EAST COAST ON SATURDAY INTO SUNDAY...AN UPPER RIDGE BUILDS IN OVER THE SE U.S. THIS WILL BRING PARTLY TO MOSTLY SUNNY SKIES...COOLER MORNING LOWS...WHILE AROUND NORMAL HIGHS EARLY...THEN A BIT WARMER SUNDAY TO MONDAY...FOR AFTERNOON HIGH TEMPS. && .LONG TERM...MONDAY THROUGH THURSDAY. THE SURFACE HIGH DRIFTS EAST OFF THE GA COAST ON MONDAY...& A GRADUALLY INFLUX OF MOISTURE RETURNS TO THE CWA WITH SOUTH FLOW. THEN THE NEXT COLD FRONT IS EXPECTED TO PUSH ACROSS THE CWA ON TUESDAY...WITH A CHANCE OF SHOWERS & TSTMS. CURRENT MODELS PUSH THE FRONT OUT OF THE CWA BY WEDNESDAY MORNING...AS FLOW BECOME NW & A SURFACE HIGH BUILDS IN FROM THE NORTH. && .MARINE.... WINDS & SEAS TO REMAIN LIGHT TODAY & INTO THE WEEKEND. NW-N FLOW WILL BECOMING E-SE INTO SUNDAY. SOME WEAK ONSHORE SEA BREEZE IS EXPECTED NEXT FEW DAYS. THEN WINDS & SEAS WILL PICK UP AHEAD OF THE NEXT FRONT ON TUESDAY. && .AVIATION... ALREADY SEEING SOME PATCHY AREAS OF FOG AT THIS HOUR WITH VLD ALREADY DOWN AROUND 3SM. IT IS ENTIRELY POSSIBLE THAT WE COULD HAVE A REPEAT TO LAST NIGHT THERE WITH VSBYS DROPPING BELOW 1 MILE IN SPOTS. LATEST IR SATELLITE IMAGERY IS ALSO SHOWING SOME LOWER CIGS STARTING TO DEVELOP. RIGHT NOW THEY ARE AROUND 5K FT...BUT SHOULD LOWER THROUGH THE NIGHT. WILL START OFF THE TAF PACKAGE WITH MVFR VSBYS AT VLD AND ABY AND QUICKLY GET THERE AT ALL OTHER SITES EXCEPT PFN NO LATER THAN 08Z. WILL DROP TO IFR CONDS IN TEMPOS AT ABY AND TLH AND DROP TO LIFR AT VLD WITH LOW CIGS BELOW FIELD MINS. EXPECT TO SEE LOW CIGS/FG LINGER INTO THE HOURS JUST PAST DAYBREAK...BUT SHOULD SEE VFR CONDS BY 14Z. FOR THE REMAINDER OF THE DAY...MUCH DRIER AIR SURFACE AND ALOFT CONTINUES TO MOVE IN AND SHOULD ONLY SEE FEW-SCT CUMULUS IN THE AFTERNOON HOURS. VFR CONDITIONS SHOULD CONTINUE THROUGH THE END OF THE TAF CYCLE. && .FIRE WEATHER... USED A DRIER MAV SET & DURATIONS OVER INLAND AREAS OF N FL FOR 35% OR LOWER ARE ONLY 1-3 HOURS. SO WILL GO WITH A STATEMENT TODAY. SATURDAY AFTERNOON WILL HAVE WATCH GOING FOR SAME AREAS. IF MORE MIXING OF DRY AIR DOES OCCUR OR TEMPS ARE A BIT WARMER...THEN RED FLAG WARNING CRITERIA COLD BE REACH. THIS WILL BE MONITORED. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 92 61 92 64 / 05 00 00 00 PANAMA CITY 89 68 90 71 / 05 00 00 00 DOTHAN 87 60 91 63 / 00 00 00 00 ALBANY 90 61 91 64 / 05 00 00 00 VALDOSTA 90 64 90 66 / 05 05 05 05 CROSS CITY 90 67 92 67 / 10 10 10 05 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...FIRE WX WATCH SATURDAY INLAND AREAS N FL. && $$ AVIATION...WOOL PUBLIC/MARINE/FIRE WX...MROCZKA PREVIOUS DISCUSSION...TREXLER/GODSEY fl AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE LOUISVILLE KY 1020 AM EDT FRI SEP 15 2006 .SHORT TERM UPDATE (REST OF THIS MORNING AND AFTERNOON)... JUST ISSUED A STATEMENT ALLOWING THE DENSE FOG ADVISORY TO EXPIRE. VSBYS IN S-CNTRL IND AND IN LOUISVILLE HAVE IMPROVED TO AROUND 5 MILES AT THIS TIME. MEANWHILE...SFC OBS AND VIS IMAGERY SHOW THAT LOW CLOUDS AND FOG CONTINUE OVER A GOOD PART OF CNTRL KY. HOWEVER... VSBYS ARE STARTING TO IMPROVE (E.G. 3 MILES AT LEX AND 5 MILES AT FFT AT 14 UTC) AS FOG LIFTS INTO LOW CLOUDS. 12 UTC SOUNDINGS FROM ILN AND OHX SHOW A SHALLOW MOIST INVERSION (BELOW 950 MB) WHICH HAS CONTRIBUTED TO THE CLOUDS AND FOG. AS THE MORNING WEARS ON AND INTO THIS AFTN...THIS INVERSION WILL DISSIPATE ALLOWING SUNSHINE TO RETURN TO MOST AREAS. THUS...SKIES WILL BECOME PARTLY TO MOSTLY SUNNY THIS AFTN. AS FOR TEMPS...THEY ARE GETTING A SLOW START DUE TO THE CLOUDS BUT WILL REBOUND THIS AFTN. NEVERTHELESS...WILL TRIM BACK VALUES A BIT OVER CNTRL KY GIVEN IT WILL STILL TAKE ANOTHER COUPLE HOURS TO SCOUR OUT CLOUD COVER. NO CHANGES TO TONIGHT'S FCST AT THIS TIME...LOOKS LIKE CLEAR SKY WITH MORE PATCHY/AREAS OF FOG BY SAT MORNING. --TWF && .PREV DISCUSSION... (ISSUED 245 AM EDT FRI SEP 15 2006) SHORT TERM (TODAY-TONIGHT)... LARGE AREA OF SFC HIGH PRES STRETCHING FROM THE GREAT LAKES SOUTHWARD INTO THE LOWER OHIO VALLEY EARLY THIS MORNING. THIS IS LEADING TO NEARLY CALM WINDS AT THE SFC...HOWEVER JUST OFF THE DECK PER VWP/ACARS DATA...10-20KT WINDS ARE OBSERVED IN THE LOWEST 1-2KFT AGL. EVEN WITH THESE WINDS...SOME AREAS OF DENSE FOG HAVE ALREADY DEVELOPED...MAINLY IN THE RURAL/FOG PRONE AREAS. 11-3.9 SAT PIX INDICATING MOST WIDESPREAD FOG IS IN AREAS S/E OF A BWG-LEX LINE AS OF 630Z. LATEST RUC INDICATES WIDESPREAD M1/4SM VSBYS DEVELOPING AFTER 9Z AS BOUNDARY LAYER WINDS LIGHTEN SLIGHTLY. WILL ISSUE A DENSE FOG ADVISORY THROUGH 14Z FOR ENTIRE CWA. BASED ON RUC DATA FOG SHOULD MIX OUT BY 14-15Z THIS MORNING... LEADING TO MOSTLY SUNNY SKIES PER NAM FCST SOUNDINGS. A FEW FLAT CU ARE EXPECTED DURING THE LATE MORNING AND AFTN HOURS...CENTERED AROUND 3KFT. TONIGHT...SKIES SHOULD LARGELY BE CLEAR WITH PERHAPS SOME WISPS OF CIRRUS DROPPING IN FROM THE NW. NAM SHOWING HIGHER RH AROUND 300MB AFTER 2Z. PATCHY FOG POSSIBLE AGAIN LATE TONIGHT. REGARDING TEMPERATURES...CONSENSUS OF NAM/GFS MOS GUIDANCE INDICATES HIGHS TODAY FROM THE UPPER 70S TO LOWER 80S AND THIS SEEMS OK. WITH CLR SKIES TONIGHT...SHELTERED/VALLEY AREAS MAY DROP INTO THE LOWER 50S...WITH MID/UPPER 50S ELSEWHERE. CS LONG TERM (SATURDAY-THURSDAY)... SATURDAY AND SUNDAY... LOWER OHIO VALLEY WILL UNDER A THIN UPPER RIDGE...WHICH IS BEING SQUEEZED BETWEEN A PERSISTENT WEAK TROUGH JUST OFF THE MID ATLANTIC COAST...AND A MUCH STRONGER FULL LATITUDE TROUGH SLOWLY PROGRESSING INTO THE HIGH PLAINS SATURDAY AND SUNDAY. EXPECT WARM...LATE SUMMERLIKE TEMPERATURES WITH PLENTY OF SUN...AND CLEAR NIGHTS. GULF MOISTURE THIS WEEKEND WILL BE CONFINED ALONG THE GULF COAST...ALTHOUGH SOME WILL BEGIN A NORTHWARD RETURN ON SUNDAY ACROSS THE LOWER MISSISSIPPI VALLEY AND INTO THE WESTERN GREAT LAKES. AT THE SURFACE...EXPECT LIGHT EAST WINDS SATURDAY THAT WILL VEER TO THE SOUTH SUNDAY AS HIGH PRESSURE MOVES EAST OF THE GREAT LAKES. SOUTH WINDS WILL INCREASE SUNDAY AFTERNOON AS A SURFACE TROUGH EXTENDING FROM AN OCCLUDED FRONT ACROSS MICHIGAN SOUTHWESTWARD ACROSS MISSOURI MOVES EASTWARD. MONDAY... 00Z OPERATIONAL GFS...LIKE ITS 00Z RUN YESTERDAY...IS DEEPER THAN ITS ENSEMBLE MODELS WITH THE CLOSED LOW EXPECTED TO MOVE ACROSS MINNESOTA MONDAY. BOTH NAM AND GFS BRING A THIN STRIP OF HIGH PRECIPITABLE WATER RIGHT ALONG A SHARP COLD FRONT EXPECTED TO MOVE ACROSS OHIO RIVER MONDAY. SURFACE BASED INSTABILITY WILL BE HIGHLY DEPENDENT ON EXACT TIMING OF FRONT...AND ANY SOLAR HEATING AVAILABLE MONDAY AHEAD OF THIS BOUNDARY. HOWEVER...UPPER DYNAMICS WILL SUGGEST GOOD CHANCE OF LINEAR CONVECTION RIGHT ALONG THE SOUTHEASTWARD MOVING BOUNDARY AND WILL MAINTAIN 50 POPS FOR CONVECTION MONDAY. TUESDAY THROUGH THURSDAY... LATEST ECMWF IS THE COOLEST WITH THE AIR BEHIND THE FRONT TUESDAY...AND BOTH OPERATIONAL MODELS HAVE BACKED OFF THE DEPTH OF THE UNSEASONABLY COLD AIR MASS EXPECTED TO MOVE INTO THE UPPER MIDWEST MONDAY. STILL EXPECT A DISTINCT COOLDOWN TUESDAY AND WEDNESDAY ACROSS THE LOWER OHIO VALLEY. BY EARLY TUESDAY...DEEP OCCLUDED CYCLONE WILL BE LOCATED OVER ONTARIO...WITH COLD FRONT ALONG THE SOUTHERN APPALACHIANS. CLEARING SHOULD PROCEED PRETTY RAPIDLY EARLY ACROSS REGION TUESDAY AS DRY AIR DESCENDS BEHIND THE DEPARTING FRONT. NORTHWEST WINDS WILL DIMINISH SOMEWHAT TUESDAY NIGHT AS SURFACE HIGH PRESSURE MOVES CLOSER. WEDNESDAY MORNING LOOKS QUITE COOL WITH UPPER 40S POSSIBLE UNDER MOSTLY CLEAR SKIES. WEDNESDAY AND THURSDAY WILL CONTINUE COOL WITH HIGHS IN GENERAL BETWEEN 5 AND 8 DEGREES BELOW NORMAL. JSD LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. .IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI NOON PM EDT FRI SEP 15 2006 .UPDATE...FOG IN THE SE HAS RAPIDLY LIFTED/DIMINISHED...AND HAVE ALLOWED DENSE FOG ADVISORY TO EXPIRE. HOWEVER...LOW CLOUDS CONTINUE TO BE WIDESPREAD IN THE VICINITY OF GLADWIN/WEST BRANCH. SATELLITE BEGINNING TO SUPPORT THINNING/EROSION OF CLOUDS...AND STILL EXPECT PARTLY SUNNY SKIES TO DEVELOP HERE BY 1 PM. OTHERWISE...SCT DECK OF CU/SC IS RAPIDLY DEVELOPING TO THE N/W OF LOW CLOUD AREA -- A BIT MORE EXTENSIVE THAN ORIGINALLY EXPECTED. WILL STAY THE COURSE WITH A MOSTLY SUNNY AFTERNOON FORECAST... BANKING ON MIXING TO EVENTUALLY ENTRAIN DRIER AIR ALOFT AND THIN CU/SC. THOUGH SCT CU WILL LINGER THROUGH THE AFTERNOON...APX/GRB/DTX 1200 UTC SOUNDINGS SUGGEST THAT CLOUDS WON/T BECOME TOO WIDESPREAD. SMITH && .PREV DISCUSSION...ISSUED 1020 AM FRI SEP 15 SURFACE REPORTS AND SATELLITE CONTINUE TO SUPPORT STUBBORN AREAS OF DENSE FOG ACROSS SE PARTS OF THE FORECAST AREA...INCLUDING THE GRAYLING...HTL...GLADWIN...AND WEST BRANCH AREAS. SATELLITE SUGGESTS THAT FOG IS RELATIVELY PATCHY IN THE GRAYLING AND HTL AREAS...AND WILL MOST LIKELY THIN QUICKEST. ON THE OTHER HAND...SOLID/DENSE LOW CLOUDS ARE ACCOMPANYING THE FOG IN GLADWIN...ARENAC...IOSCO...AND PARTS OF OGEMAW COUNTIES. FOG WILL LIKELY BE SLOWER TO DIMINISH HERE...GIVEN TOUGHER TIME INSOLATION WILL HAVE INITIATING MIXING. HAVE CONSEQUENTLY EXTENDED DENSE FOG ADVISORY THROUGH NOON FOR SEVERAL SE COUNTIES. PATCHY DENSE FOG HAS ALSO DEVELOPED VICINITY OF THE ST MARYS RIVER AND THE SAULT...BUT SHOULD QUICKLY THIN NEXT HOUR OR SO AND WILL NOT ISSUE ADVISORY. ALL OTHER AREAS ARE SUNNY THIS MORNING. 1200 UTC APX SOUNDING SHOWS SHALLOW MOISTURE WITHIN NOCTURNAL SURFACE INVERSION...BUT NOTHING A MID SEPTEMBER SUN SHOULDN/T BE ABLE TO EVENTUALLY MIX OUT. MIXING PROCESS WILL LIKELY GIVE RISE TO A SHALLOW SCT SC/CU DECK INTO EARLY AFTERNOON AWAY FROM THE GREAT LAKES -- THOUGH MOST AREAS WILL BE MOSTLY SUNNY THIS AFTERNOON. EXCEPTION WILL BE FAR SE...WHERE CURRENT CLOUDS AND (JUST UPSTREAM) ORIENTATION OF LOW LEVEL RIDGING SUGGESTS A MORE BKN DECK OF SC/CU THIS AFTERNOON. 1200 UTC APX SOUNDING AND LIKELY MIXING DEPTH SUGGESTS THAT GOING HIGH TEMP FORECAST IS STILL ON TARGET...WITH LOWER-MID 70S EXPECTED. SMITH PREV DISCUSSION...ISSUED 704 AM FRI SEP 15 UPDATE...PER EARLIER DISCUSSION WILL CANCEL FOG ADVISORY EARLY FOR MBL/FRANKFORT/TVC. SUSPECT MOST OF WEXFORD IS IN DECENT SHAPE TOO...BUT WITH CAD AT 1/4SM AT THE MOMENT WILL LEAVE THAT ONE IN. NO OTHER CHANGES EXCEPT MINOR CLOUD COVER TWEAKS. PREV DISCUSSION...ISSUED 500 AM FRI SEP 15 UPDATE...EXPANDING DENSE FOG ADVIS INTO OTSEGO. NO OTHER CHANGES. NOT WILLING TO GIVE UP ON HEADLINE YET WEST OF US-131...THOUGH TO THIS POINT TVC AND THE COAST HAVE NOT SEEN MUCH FOG YET. COULD CANCEL THOSE COUNTIES AROUND SUNRISE IF THINGS DO NOT CHANGE...STILL A COUPLE OF HOURS TO GO YET. JZ PREV DISCUSSION...ISSUED 345 AM FRI SEP 15 03Z SURFACE/RUC ANALYSIS AND IR/WV IMAGERY SHOW A LARGE-SCALE TROUGH DIGGING OVER THE WEST COAST...AND A RELATIVELY FLATTENED RIDGE PARKED ACROSS THE MIDDLE CONUS. HIGH PRESSURE AT THE SURFACE CENTERED NE OF THE GEORGIAN BAY UNDER NORTHERLY FLOW ALOFT. THIS HIGH PRESSURE COMBINED WITH 500MB RIDGING WHOSE AXIS RUNS ALONG THE MISSISSIPPI RIVER VALLEY AND VERY DRY AIR ALOFT HAS ALLOWED FOR EXCELLENT RADIATIONAL COOLING CONDITIONS ACROSS THE CWA. THESE CONDITIONS HAVE HELPED WIDESPREAD FOG TO FORM ALREADY...MOSTLY CONFINED TO INLAND AREAS SOUTH OF M-32 AS NOTED BY OBS (ACB...3/4SM....GOV....1/2SM...HTL...1/4SM) AND 11U-3.9U SATELLITE IMAGERY. TEMPERATURES HAVE FALLEN INTO THE MIDDLE 40S TO LOWER 50S AND MOST PLACES ARE AT OR BELOW THEIR CROSSOVER TEMPS WITH THE EXCEPTION OF EASTERN UPPER. WITH NO PRECIP IN THE PICTURE UNTIL SUNDAY MORNING...MAIN FORECAST CONCERNS IN THE SHORT TERM REVOLVE AROUND FOG HEADLINES THIS MORNING. FOG HEADLINES....NOT SURPRISINGLY...FOG HAS BEEN ON THE INCREASE THIS MORNING AS TEMPS COOL. CURRENT OBS AND SATELLITE TRENDS SUPPORT KEEPING THE DENSE FOG ADVISORY GOING FOR AREAS SOUTH OF M-72. THE QUESTION IS WHETHER FOG WILL BECOME THICK ENOUGH OVER NORTHERN LOWER NORTH OF THIS LINE TO WARRANT HEADLINES? TEMPS HAVE FALLEN AT OR BELOW THE CROSSOVER TEMP FOR MANY LOCATIONS ACROSS THIS AREA BUT FOG HAS NOT FORMED NEARLY AS QUICK AS THEIR COUNTERPARTS TO THE SOUTH (07Z GLR JUST WENT 1/4SM FG BUT IS ONLY SITE NORTH OF M-72). WITH FURTHER COOLING TO TAKE PLACE THIS MORNING...EXPECT FOG TO BECOME MORE WIDESPREAD...BUT AM RELUCTANT TO CHANGE HEADLINES UNTIL MORE EVIDENCE BECOMES APPARENT FROM THE OBS. WILL HAVE TO KEEP AN EYE ON THINGS THROUGH THE EARLY MORNING HOURS. FOR THE REMAINDER OF TODAY...ANOTHER FANTASTIC DAY ON TAP...ONCE THE FOG LIFTS THIS MORNING. STRONG SUBSIDENCE AS NOTED BY THE 850-500MB RH 10 TO 20 PCT WILL PREVAIL WITH RIDGING AT THE SURFACE AND ALOFT. THIS SUBSIDENCE WILL INCREASE THROUGH THE DAY AS HEIGHT RISES TAKE PLACE WITH THE 500MB RIDGE STRENGTHENING AS IT PASSES OVERHEAD. ONCE THE FOG BURNS OFF THIS MORNING...LINGERING MOISTURE BELOW THE SUBSIDENCE INVERSION AS NOTED BY AN ACARS SOUNDING FROM APN (DEWPOINT 9C AT 925MB) LATE LAST EVENING WILL PROMOTE FLAT CU BUILD UP ESPECIALLY ACROSS THE HIGHER TERRAIN. WITH MIXING OF THE DRY AIR ABOVE...THIS CU WILL DIMINISH DURING THE MIDDLE OF THE AFTERNOON...LEAVING MOST LOCATIONS MOSTLY SUNNY. 850MB TEMPS INCREASE A DEGREE OR TWO...RANGING FROM 12-13C ACROSS NORTHERN LOWER...TO 13-14C OVER EASTERN UPPER...SO WE WILL SEE HIGHS MOSTLY IN THE MIDDLE 70S. THESE TEMPS...COMBINED WITH THE LIGHT WINDS WITH THE RIDGING...WILL PROMOTE LAKE BREEZES THIS AFTERNOON (950MB WINDS 5-10KTS NORTHERN LOWER AND 10-15KTS EASTERN UPPER)...AND WILL KEEP AREAS NEAR THE LAKES A FEW DEGREES COOLER. MPC LATER PERIODS...UPPER RIDGE AXIS WILL GRADUALLY SLIDE FROM THE CENTRAL TO THE EASTERN LAKES...AS AN IMPRESSIVE UPPER LOW GETS CARVED OUT IN THE NORTHERN PLAINS. QUIET WX LOOKS TO PREVAIL THRU SATURDAY...BUT A COLD FRONT WILL SLOWLY APPROACH FROM THE WEST FOR THE TAIL END OF THE WEEKEND. PRECIP CHANCES FROM SAT NIGHT ONWARD ARE THE MAIN CHALLENGE. MODELS...NAM IS RATHER FAST WITH THE COLD FRONT...NEARING LAKE MI BY SUNDAY MORNING. THE GFS STILL HAS THE BOUNDARY ON THE OTHER SIDE OF WI. SREF STARTS SLOW BUT ALMOST CATCHES UP WITH THE NAM...NGM (FOR WHAT IT/S WORTH) IS ALSO FAST...CANADIAN IS SLOW. NAM/GFS BOTH SHOWING GOOD CONSISTENCY. WILL LEAN TOWARD THE SLOW SIDE PER USUAL MODEL BIASES...BUT THAT STILL MEANS BRINGING IN RAIN FASTER THAN EARLIER FORECAST. TONIGHT/SATURDAY...WX CONCERNS FAIRLY MINIMAL. ANOTHER CLEAR AND STILL NIGHT TONIGHT WILL RESULT IN FOG. BUT SHOULD NOT BE AS MUCH FOG AS THIS MORNING...AFTER ANOTHER DAY OF GOOD DIURNAL MIXING AND WITH THE SURFACE HIGH MOVING EAST OF THE FORECAST AREA. WILL STAY TOWARD THE COOL END OF GUIDANCE TEMPS. MAY HAVE SOME CU/STRATOCU IN EASTERN UPPER MI SATURDAY...AS DEVELOPING SE SUB-900MB WINDS BRING IN SOME EXTRA MOISTURE OFF OF HURON. AND SOME CIRRUS WILL ARRIVE IN NORTHERN/WESTERN ZONES LATE. OTHERWISE...PLENTY OF SUNSHINE...WITH MAX TEMPS IN THE 70S...PERHAPS JUST TOUCHING 80 IN THE SOUTHERN ZONES (LIKE TVC...WHICH WILL BENEFIT FROM A DOWNSLOPING SOUTH WIND). SATURDAY NIGHT...DEVELOPING 850MB LOW LEVEL JET WILL PUNCH FROM KS INTO WI. THIS WILL BRING AN 850MB THETA-E RIDGE EAST WITH TIME...POKING INTO THE NORTHERN AND WESTERN ZONES LATE. INCREASING WARM/MOIST ADVECTION WILL SUPPORT A BAND OF SHOWERS (AND MAYBE AN EMBEDDED THUNDERSTORM) TRYING TO WORK ACROSS LAKE MI OVERNIGHT. INSTABILITY PROGS FROM EVEN THE AGGRESSIVE NAM DO NOT SUPPORT THUNDER THIS FAR EAST (ONLY 100-200 MUCAPE). BUT RAPID SATURATION OF THE MID AND LOW LEVELS AFTER 09Z MAY ALLOW SOME SHOWERS TO WORK IN FROM THE WEST. WILL HAVE A SMALL CHANCE OF PRECIP AFTER 08Z FROM CAD TO DE TOUR AND WEST. OTHERWISE...MID/HIGH CLOUDS WILL BE THICKENING EVERYWHERE...WITH DRY AIR BELOW 700MB PRECLUDING PRECIP. WILL BE A RELATIVELY WARM NIGHT WITH CLOUDS AND NO DECOUPLING...MIN TEMPS MAINLY UPPER 50S TO LOWER 60S. SUNDAY...850MB THETA-E RIDGE WILL TAKE IT/S TIME WORKING INTO AND ACROSS THE FORECAST AREA. FORCING/DYNAMICS ARE NOT ESPECIALLY IMPRESSIVE...AS THE LOW LEVEL JET DOES IT/S USUAL EARLY MORNING DECAY...AND UPSTREAM COLD FRONT WILL ONLY APPROACH LAKE MI TOWARD EVENING (AS LONG AS THE SLOWER SOLUTIONS HOLD). EXPECT A WEAKENING BAND OF SHOWERS TO PRESS FURTHER EAST IN THE MORNING BEFORE COMPLETELY FALLING APART. THEN IT FALLS TO HOW MUCH HEATING WE CAN SEE. WITH 850MB TEMPS +16/17C...MAX TEMPS WILL NEED TO BE NEAR 80 TO ALLOW SURFACE BASED INSTABILITY TO COOK OFF SOME STORMS. WE MIGHT GET THERE GIVEN THE EXPECTED MILD START TO THE DAY...BUT WITH A FAIR AMOUNT OF CLOUD COVER 80 IS PROBABLY THE TOP END. END RESULT...WILL HAVE A CHANCE OF SHRA MOST EVERYWHERE IN THE MORNING...AND ADD TSRA FOR THE AFTERNOON. WILL LEAVE PRECIP OUT NEAR SAGINAW BAY WHERE SURFACE RIDGING AND LOW LEVEL DRY AIR WILL TRY TO HANG ON THE LONGEST. REST OF THE FORECAST...WILL REMOVE THUNDER FROM EASTERN UPPER/NW LOWER MI MONDAY. COLD FRONT GOES THRU EARLY AND STRONG LOW LEVEL COLD ADVECTION IS WELL AHEAD OF THE COLD CORE ALOFT. WILL LEAVE THUNDER IN NE LOWER...THOUGH CURRENT PREFERRED TIMING SUGGEST EARLY MORNING WILL BE THE BEST SHOT THERE. WILL TREND TEMPS DOWNWARD A BIT MORE MONDAY AND ESPECIALLY TUESDAY...AS MODELS ARE CONSISTENT IN SHOWING A FAIRLY DRASTIC COLD SNAP FOR THIS TIME OF YEAR. (NOTE THE POSSIBILITY OF ACCUMULATING SNOW OVER THE WEEKEND IN THE MT/ND BORDER AREA. FOLKS...SUMMER IS ENDING.) ZOLTOWSKI && .APX...WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1045 AM EDT FRI SEP 15 2006 .DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST UPDATE IS THE HIGH TEMPERATURES FOR THIS AFTERNOON. WATER VAPOR IMAGERY AND RUC SHOW A LARGE RIDGE ACROSS THE UPPER GREAT LAKES...A CLOSED LOW OVER THE MIDDLE ATLANTIC STATES...AND A DEEP LOW OVER THE PACIFIC NORTHWEST. A WEAK SHORTWAVE MOVING THROUGH THE RIDGE IS OVER THE FORECAST AREA. SURFACE ANALYSIS INDICATES A LARGE RIDGE OVER THE UPPER GREAT LAKES...A DEEP LOW OVER WESTERN SOUTH DAKOTA. A FRONTAL SYSTEM LEADS THE LOW AND STRETCHES NORTHEAST THROUGH CENTRAL ONTARIO. DRY AIR IS ENTRENCHED OVER ALL OVER THE UPPER GREAT LAKES AND ENTIRE MISSISSIPPI RIVER VALLEY. FOG WAS OVER MUCH OF THE SOUTHERN COUNTIES OF THE CWA THIS MORNING AND IS GRADUALLY BURNING OFF. THE RIDGE WILL CONTINUE OVER THE FORECAST AREA THROUGH THE AFTERNOON...AND THE SHORTWAVE WILL REMAIN IN PLACE OVER THE EASTERN U.P. THE SURFACE RIDGE LIKEWISE WILL REMAIN OVER THE UPPER GREAT LAKES KEEPING THE AIR MASS DRY...WHILE THE SOUTH DAKOTA LOW WILL EXTEND NORTH INTO WESTERN NORTH DAKOTA. VISIBLE SATELLITE STILL SHOWING SOME FOG OVER THE CENTRAL U.P. THIS SHOULD BURN SHORTLY. OTHERWISE...SKIES ARE MOSTLY CLEAR...PROVIDING A LOT OF SUN FOR THE AREA. TEMPERATURES ARE SLIGHTLY BELOW GUIDANCE AT THIS POINT OVER THE WEST AND NORTH CENTRAL. HOWEVER...THEY SHOULD CATCH UP AS THE SUN RISES. FOR THE EAST AND ALONG THE LAKE MICHIGAN SHORE TEMPERATURES ARE A LITTLE ABOVE GUIDANCE. HOWEVER...THE DEW POINTS ARE A LITTLE ABOVE GUIDANCE AS WELL. ALSO THERE IS A LITTLE MORE CLOUD COVER ALONG THE LAKE MICHIGAN SHORE. THE HIGHER DEW POINTS AND CLOUD COVER SHOULD LIMIT HEATING THIS AFTERNOON. PLAN TO LEAVE THE FORECAST PRETTY MUCH AS IS BUT WILL UPDATE FOR WORDING. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1020 AM EDT FRI SEP 15 2006 .UPDATE...SURFACE REPORTS AND SATELLITE CONTINUE TO SUPPORT STUBBORN AREAS OF DENSE FOG ACROSS SE PARTS OF THE FORECAST AREA...INCLUDING THE GRAYLING...HTL...GLADWIN...AND WEST BRANCH AREAS. SATELLITE SUGGESTS THAT FOG IS RELATIVELY PATCHY IN THE GRAYLING AND HTL AREAS...AND WILL MOST LIKELY THIN QUICKEST. ON THE OTHER HAND...SOLID/DENSE LOW CLOUDS ARE ACCOMPANYING THE FOG IN GLADWIN...ARENAC...IOSCO...AND PARTS OF OGEMAW COUNTIES. FOG WILL LIKELY BE SLOWER TO DIMINISH HERE...GIVEN TOUGHER TIME INSOLATION WILL HAVE INITIATING MIXING. HAVE CONSEQUENTLY EXTENDED DENSE FOG ADVISORY THROUGH NOON FOR SEVERAL SE COUNTIES. PATCHY DENSE FOG HAS ALSO DEVELOPED VICINITY OF THE ST MARYS RIVER AND THE SAULT...BUT SHOULD QUICKLY THIN NEXT HOUR OR SO AND WILL NOT ISSUE ADVISORY. ALL OTHER AREAS ARE SUNNY THIS MORNING. 1200 UTC APX SOUNDING SHOWS SHALLOW MOISTURE WITHIN NOCTURNAL SURFACE INVERSION...BUT NOTHING A MID SEPTEMBER SUN SHOULDN/T BE ABLE TO EVENTUALLY MIX OUT. MIXING PROCESS WILL LIKELY GIVE RISE TO A SHALLOW SCT SC/CU DECK INTO EARLY AFTERNOON AWAY FROM THE GREAT LAKES -- THOUGH MOST AREAS WILL BE MOSTLY SUNNY THIS AFTERNOON. EXCEPTION WILL BE FAR SE...WHERE CURRENT CLOUDS AND (JUST UPSTREAM) ORIENTATION OF LOW LEVEL RIDGING SUGGESTS A MORE BKN DECK OF SC/CU THIS AFTERNOON. 1200 UTC APX SOUNDING AND LIKELY MIXING DEPTH SUGGESTS THAT GOING HIGH TEMP FORECAST IS STILL ON TARGET...WITH LOWER-MID 70S EXPECTED. SMITH && .PREV DISCUSSION...ISSUED 704 AM FRI SEP 15 UPDATE...PER EARLIER DISCUSSION WILL CANCEL FOG ADVISORY EARLY FOR MBL/FRANKFORT/TVC. SUSPECT MOST OF WEXFORD IS IN DECENT SHAPE TOO...BUT WITH CAD AT 1/4SM AT THE MOMENT WILL LEAVE THAT ONE IN. NO OTHER CHANGES EXCEPT MINOR CLOUD COVER TWEAKS. PREV DISCUSSION...ISSUED 500 AM FRI SEP 15 UPDATE...EXPANDING DENSE FOG ADVIS INTO OTSEGO. NO OTHER CHANGES. NOT WILLING TO GIVE UP ON HEADLINE YET WEST OF US-131...THOUGH TO THIS POINT TVC AND THE COAST HAVE NOT SEEN MUCH FOG YET. COULD CANCEL THOSE COUNTIES AROUND SUNRISE IF THINGS DO NOT CHANGE...STILL A COUPLE OF HOURS TO GO YET. JZ PREV DISCUSSION...ISSUED 345 AM FRI SEP 15 03Z SURFACE/RUC ANALYSIS AND IR/WV IMAGERY SHOW A LARGE-SCALE TROUGH DIGGING OVER THE WEST COAST...AND A RELATIVELY FLATTENED RIDGE PARKED ACROSS THE MIDDLE CONUS. HIGH PRESSURE AT THE SURFACE CENTERED NE OF THE GEORGIAN BAY UNDER NORTHERLY FLOW ALOFT. THIS HIGH PRESSURE COMBINED WITH 500MB RIDGING WHOSE AXIS RUNS ALONG THE MISSISSIPPI RIVER VALLEY AND VERY DRY AIR ALOFT HAS ALLOWED FOR EXCELLENT RADIATIONAL COOLING CONDITIONS ACROSS THE CWA. THESE CONDITIONS HAVE HELPED WIDESPREAD FOG TO FORM ALREADY...MOSTLY CONFINED TO INLAND AREAS SOUTH OF M-32 AS NOTED BY OBS (ACB...3/4SM....GOV....1/2SM...HTL...1/4SM) AND 11U-3.9U SATELLITE IMAGERY. TEMPERATURES HAVE FALLEN INTO THE MIDDLE 40S TO LOWER 50S AND MOST PLACES ARE AT OR BELOW THEIR CROSSOVER TEMPS WITH THE EXCEPTION OF EASTERN UPPER. WITH NO PRECIP IN THE PICTURE UNTIL SUNDAY MORNING...MAIN FORECAST CONCERNS IN THE SHORT TERM REVOLVE AROUND FOG HEADLINES THIS MORNING. FOG HEADLINES....NOT SURPRISINGLY...FOG HAS BEEN ON THE INCREASE THIS MORNING AS TEMPS COOL. CURRENT OBS AND SATELLITE TRENDS SUPPORT KEEPING THE DENSE FOG ADVISORY GOING FOR AREAS SOUTH OF M-72. THE QUESTION IS WHETHER FOG WILL BECOME THICK ENOUGH OVER NORTHERN LOWER NORTH OF THIS LINE TO WARRANT HEADLINES? TEMPS HAVE FALLEN AT OR BELOW THE CROSSOVER TEMP FOR MANY LOCATIONS ACROSS THIS AREA BUT FOG HAS NOT FORMED NEARLY AS QUICK AS THEIR COUNTERPARTS TO THE SOUTH (07Z GLR JUST WENT 1/4SM FG BUT IS ONLY SITE NORTH OF M-72). WITH FURTHER COOLING TO TAKE PLACE THIS MORNING...EXPECT FOG TO BECOME MORE WIDESPREAD...BUT AM RELUCTANT TO CHANGE HEADLINES UNTIL MORE EVIDENCE BECOMES APPARENT FROM THE OBS. WILL HAVE TO KEEP AN EYE ON THINGS THROUGH THE EARLY MORNING HOURS. FOR THE REMAINDER OF TODAY...ANOTHER FANTASTIC DAY ON TAP...ONCE THE FOG LIFTS THIS MORNING. STRONG SUBSIDENCE AS NOTED BY THE 850-500MB RH 10 TO 20 PCT WILL PREVAIL WITH RIDGING AT THE SURFACE AND ALOFT. THIS SUBSIDENCE WILL INCREASE THROUGH THE DAY AS HEIGHT RISES TAKE PLACE WITH THE 500MB RIDGE STRENGTHENING AS IT PASSES OVERHEAD. ONCE THE FOG BURNS OFF THIS MORNING...LINGERING MOISTURE BELOW THE SUBSIDENCE INVERSION AS NOTED BY AN ACARS SOUNDING FROM APN (DEWPOINT 9C AT 925MB) LATE LAST EVENING WILL PROMOTE FLAT CU BUILD UP ESPECIALLY ACROSS THE HIGHER TERRAIN. WITH MIXING OF THE DRY AIR ABOVE...THIS CU WILL DIMINISH DURING THE MIDDLE OF THE AFTERNOON...LEAVING MOST LOCATIONS MOSTLY SUNNY. 850MB TEMPS INCREASE A DEGREE OR TWO...RANGING FROM 12-13C ACROSS NORTHERN LOWER...TO 13-14C OVER EASTERN UPPER...SO WE WILL SEE HIGHS MOSTLY IN THE MIDDLE 70S. THESE TEMPS...COMBINED WITH THE LIGHT WINDS WITH THE RIDGING...WILL PROMOTE LAKE BREEZES THIS AFTERNOON (950MB WINDS 5-10KTS NORTHERN LOWER AND 10-15KTS EASTERN UPPER)...AND WILL KEEP AREAS NEAR THE LAKES A FEW DEGREES COOLER. MPC LATER PERIODS...UPPER RIDGE AXIS WILL GRADUALLY SLIDE FROM THE CENTRAL TO THE EASTERN LAKES...AS AN IMPRESSIVE UPPER LOW GETS CARVED OUT IN THE NORTHERN PLAINS. QUIET WX LOOKS TO PREVAIL THRU SATURDAY...BUT A COLD FRONT WILL SLOWLY APPROACH FROM THE WEST FOR THE TAIL END OF THE WEEKEND. PRECIP CHANCES FROM SAT NIGHT ONWARD ARE THE MAIN CHALLENGE. MODELS...NAM IS RATHER FAST WITH THE COLD FRONT...NEARING LAKE MI BY SUNDAY MORNING. THE GFS STILL HAS THE BOUNDARY ON THE OTHER SIDE OF WI. SREF STARTS SLOW BUT ALMOST CATCHES UP WITH THE NAM...NGM (FOR WHAT IT/S WORTH) IS ALSO FAST...CANADIAN IS SLOW. NAM/GFS BOTH SHOWING GOOD CONSISTENCY. WILL LEAN TOWARD THE SLOW SIDE PER USUAL MODEL BIASES...BUT THAT STILL MEANS BRINGING IN RAIN FASTER THAN EARLIER FORECAST. TONIGHT/SATURDAY...WX CONCERNS FAIRLY MINIMAL. ANOTHER CLEAR AND STILL NIGHT TONIGHT WILL RESULT IN FOG. BUT SHOULD NOT BE AS MUCH FOG AS THIS MORNING...AFTER ANOTHER DAY OF GOOD DIURNAL MIXING AND WITH THE SURFACE HIGH MOVING EAST OF THE FORECAST AREA. WILL STAY TOWARD THE COOL END OF GUIDANCE TEMPS. MAY HAVE SOME CU/STRATOCU IN EASTERN UPPER MI SATURDAY...AS DEVELOPING SE SUB-900MB WINDS BRING IN SOME EXTRA MOISTURE OFF OF HURON. AND SOME CIRRUS WILL ARRIVE IN NORTHERN/WESTERN ZONES LATE. OTHERWISE...PLENTY OF SUNSHINE...WITH MAX TEMPS IN THE 70S...PERHAPS JUST TOUCHING 80 IN THE SOUTHERN ZONES (LIKE TVC...WHICH WILL BENEFIT FROM A DOWNSLOPING SOUTH WIND). SATURDAY NIGHT...DEVELOPING 850MB LOW LEVEL JET WILL PUNCH FROM KS INTO WI. THIS WILL BRING AN 850MB THETA-E RIDGE EAST WITH TIME...POKING INTO THE NORTHERN AND WESTERN ZONES LATE. INCREASING WARM/MOIST ADVECTION WILL SUPPORT A BAND OF SHOWERS (AND MAYBE AN EMBEDDED THUNDERSTORM) TRYING TO WORK ACROSS LAKE MI OVERNIGHT. INSTABILITY PROGS FROM EVEN THE AGGRESSIVE NAM DO NOT SUPPORT THUNDER THIS FAR EAST (ONLY 100-200 MUCAPE). BUT RAPID SATURATION OF THE MID AND LOW LEVELS AFTER 09Z MAY ALLOW SOME SHOWERS TO WORK IN FROM THE WEST. WILL HAVE A SMALL CHANCE OF PRECIP AFTER 08Z FROM CAD TO DE TOUR AND WEST. OTHERWISE...MID/HIGH CLOUDS WILL BE THICKENING EVERYWHERE...WITH DRY AIR BELOW 700MB PRECLUDING PRECIP. WILL BE A RELATIVELY WARM NIGHT WITH CLOUDS AND NO DECOUPLING...MIN TEMPS MAINLY UPPER 50S TO LOWER 60S. SUNDAY...850MB THETA-E RIDGE WILL TAKE IT/S TIME WORKING INTO AND ACROSS THE FORECAST AREA. FORCING/DYNAMICS ARE NOT ESPECIALLY IMPRESSIVE...AS THE LOW LEVEL JET DOES IT/S USUAL EARLY MORNING DECAY...AND UPSTREAM COLD FRONT WILL ONLY APPROACH LAKE MI TOWARD EVENING (AS LONG AS THE SLOWER SOLUTIONS HOLD). EXPECT A WEAKENING BAND OF SHOWERS TO PRESS FURTHER EAST IN THE MORNING BEFORE COMPLETELY FALLING APART. THEN IT FALLS TO HOW MUCH HEATING WE CAN SEE. WITH 850MB TEMPS +16/17C...MAX TEMPS WILL NEED TO BE NEAR 80 TO ALLOW SURFACE BASED INSTABILITY TO COOK OFF SOME STORMS. WE MIGHT GET THERE GIVEN THE EXPECTED MILD START TO THE DAY...BUT WITH A FAIR AMOUNT OF CLOUD COVER 80 IS PROBABLY THE TOP END. END RESULT...WILL HAVE A CHANCE OF SHRA MOST EVERYWHERE IN THE MORNING...AND ADD TSRA FOR THE AFTERNOON. WILL LEAVE PRECIP OUT NEAR SAGINAW BAY WHERE SURFACE RIDGING AND LOW LEVEL DRY AIR WILL TRY TO HANG ON THE LONGEST. REST OF THE FORECAST...WILL REMOVE THUNDER FROM EASTERN UPPER/NW LOWER MI MONDAY. COLD FRONT GOES THRU EARLY AND STRONG LOW LEVEL COLD ADVECTION IS WELL AHEAD OF THE COLD CORE ALOFT. WILL LEAVE THUNDER IN NE LOWER...THOUGH CURRENT PREFERRED TIMING SUGGEST EARLY MORNING WILL BE THE BEST SHOT THERE. WILL TREND TEMPS DOWNWARD A BIT MORE MONDAY AND ESPECIALLY TUESDAY...AS MODELS ARE CONSISTENT IN SHOWING A FAIRLY DRASTIC COLD SNAP FOR THIS TIME OF YEAR. (NOTE THE POSSIBILITY OF ACCUMULATING SNOW OVER THE WEEKEND IN THE MT/ND BORDER AREA. FOLKS...SUMMER IS ENDING.) ZOLTOWSKI && .APX...WATCHES/WARNINGS/ADVISORIES...DENSE FOG ADVISORY UNTIL NOON... MIZ028>030-034>036-041-042 && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1022 AM EDT FRI SEP 15 2006 .UPDATE... VISIBILITIES CONTINUE TO LIFT ACROSS SOUTHEAST MICHIGAN...ENOUGH TO DROP THE FOG ADVISORY. ONLY LINGERING CONCERN IS ACROSS THE SAGINAW VALLEY. MBS HAS RECENTLY CLIMBED TO MVFR FOG...AN HOUR OR SO BEHIND HYX. THERE WILL BE SOME FOG LINGERING BETWEEN MBS AND MOP/AMN WHICH ARE STILL 1/4SM OR LESS...BUT A TIMING TO THIS EDGE SHOWS A SLOW AND STEADY WESTWARD PROGRESS. OTHERWISE VIS SATELLITE SHOWS THE MVFR STATUS THAT HELPED DISSIPATE THE FOG ACROSS THE EASTERN CWA IS HOLDING FAST. EXPECT THAT ANY THIN SPOTS IN THE CLOUDS WILL FILL IN SOON WITH CU...AND THAT THE STATUS ITSELF WILL TAKE ON A MORE CELLULAR/DIURNAL LOOK. MODELS CONTINUE TO HAVE A POOR HANDLE ON THE AMOUNT OF LOW-LEVEL MOISTURE ACROSS THE REGION...WITH 14Z TAMDAR SOUNDINGS OUT OF DTW NEARLY SATURATED BELOW 900MB...WHILE THE 14Z RUC INITIALIZATION SHOWS DEWPOINT DEPRESSIONS OF UP TO 7C IN THE SAME LAYER. NOT TOO MUCH DRY AIR ADVECTION EXPECTED...WITH CLOUD EROSION THROUGH MIXING INTO THE MUCH DRIER AIR ALOFT. WILL INCREASE SKY COVER...CARRYING MOSTLY CLOUDY THROUGH THE BULK OF THE DAY...ONLY CLOUDS ONLY BEGINNING TO MIX OUT BY LATE AFTERNOON. GIVEN THE EXPECTED DIURNAL TRANSITION FROM STATUS TO CU...CLOUDS SHOULD DIMINISH QUICKLY WITH SUNSET LEAVING MOSTLY CLEAR CONDITIONS AFTER 00Z. WILL ALSO DROP HIGH TEMPERATURES A FEW DEGREES GIVEN LIMITED INSOLATION. && .PREV DISCUSSION...ISSUED 750 AM EDT FRI SEP 15 2006 AVIATION... DENSE FOG WAS CAUSING LIFR CONDITIONS AT MBS/FNT. A LOW STRATUS DECK OF ABOUT 1000-1500 HAS BEEN MOVING WESTWARD AND SOUTHWARD. THIS DECK HAS BEEN WIPING OUT FOG AS IT MOVES ALONG LEAVING DET/DTW WITH MVFR CEILINGS. AS THE DAY HEATS UP...THIS DECK SHOULD STOP EXPANDING AND BEGIN MIXING OUT THIS MORNING LEAVING GENERALLY SCT CONDITIONS. SOUNDINGS SHOWS SOME INSTABILITY IN LOW LEVELS SO COULD SEE OCCASIONAL BKN 2500FT MVFR CEILINGS IN THE AFTERNOON... ESPECIALLY DET/DTW WHERE LOW LEVEL MOISTURE WILL BE A BIT MORE AVAILABLE. SHORT TERM...TODAY AND TONIGHT SURFACE HIGH AND UPPER RIDGE WILL BE OVER HEAD TODAY AND TONIGHT. FORECAST PROBLEM WILL BE FOG AND CLOUD COVER THIS MORNING. LARGE SHIELD OF LOW STRATUS HAS BEEN WORKING BACK AROUND UPPER LOW SYSTEM OVER PENNSYLVANIA INTO THE EASTERN THUMB AND IS CONTINUING TO SPREAD SOUTH AND WESTWARD UNDER INVERSION. THIS IS ALSO BEING HELPED BY WEAK SURFACE TROUGHING EXTENDING BACK WEST INTO THUMB. GFS SEEMS TO HAVE THE BEST HANDLE ON THIS LOOKING AT THE 925-950MB MOISTURE FIELD. LOW CLOUDS WILL LIKELY MAKE IT NO FURTHER WEST THEN US23/US23/I75 LINE. WILL CONTINUE THE DENSE FOG ADVISORY UNTIL 14Z AS MOST OBSERVATIONS SHOWING VISIBILITIES 1/4 MILE OR LESS...EXCEPTIONS HAVE BEEN MOST OF WAYNE COUNTY WHERE URBAN HEAT ISLAND AFFECT SEEMS TO HAVE KEPT DEW POINT SPREAD APART FAR ENOUGH TO LIMIT FOG DEVELOPMENT SO FAR AND EASTERN MACOMB COUNTY WHERE CLOUD COVER HAS PREVENT DECENT RADIATIONAL COOLING. STILL SEVERAL HOURS TO GO BEFORE SUNRISE SO DO EXPECT SOME DEGREE OF FOG TO DEVELOP IN THESE AREAS BUT MORE OF PATCHY DENSE FOG THEN WIDESPREAD. FOG AND CLOUDS WILL MIX AND DISSIPATE OUT BY NOON. MODEL SOUNDINGS SHOW ENOUGH INSTABILITY AND LOW LEVEL MOISTURE ACROSS EASTERN PORTIONS OF CWA TO GENERATE SCT-BKN CU THIS AFTERNOON SO WILL CARRY PARTLY CLOUDY THOSE AREAS AND MOSTLY SUNNY ELSEWHERE. SHOULD HAVE CLEAR SKIES TONIGHT WITH OUT ANY LOW LEVEL CLOUD INTRUSION LIKE OVERNIGHT. EXPECT GOOD RADIATIONAL COOLING AGAIN TONIGHT SO WILL CARRY AREAS OF FOG. NOT EXPECTING WIDESPREAD DENSE FOG BUT WILL LIKELY SEE PATCHY DENSE FOG. WILL GO WITH WARMER GFS NUMBERS AS MET GUIDANCE UNDER DID YESTERDAYS HIGHS AND SEEMS A BIT LOW FOR TODAY. LONG TERM...SATURDAY THROUGH THURSDAY A BRIEF WARM UP THEN AUTUMN CONDITIONS SETTLE INTO THE GREAT LAKES FOR NEXT WEEK (BUT NOT AS EMPHATIC PER THE GFS). LARGE SCALE PATTERN SHIFT IS UNDERWAY WITH DEEP AND COLD TROUGH ACROSS THE PACIFIC NORTHWEST INTO THE FOUR CORNERS REGION AND SURFACE LEE-CYCLOGENESIS ACROSS THE WESTERN DAKOTAS. IN TURN THE DOWNSTREAM RIDGE CONTINUES TO AMPLIFY WITH STRENGTHENING SURFACE HIGH ACROSS THE MIDWEST AND TENNESSEE VALLEY THAT WILL REMAIN IN PLACE THROUGH SATURDAY. MODELS ARE CONSISTENT WITH OCCLUDED FRONT IN THE GREAT LAKES SUNDAY NIGHT INTO MONDAY MORNING. THE NMM/CANADIAN SUGGEST 500MB WAVE ON THE ENTRANCE SIDE OF THE JET WILL AMPLIFY AND TRACK INTO THE STATE LATE SUNDAY BUT CONSENSUS FROM THE GFS/ECMWF SUGGEST HOLDING OFF UNTIL SUNDAY NIGHT GIVEN STRENGTH OF UPSTREAM TROUGH AND TRENDS SUGGEST A LITTLE SLOWER PROGRESS. THIS CONTINUES WITH THE CHANCE FOR SHOWERS/THUNDERSTORMS SUNDAY NIGHT INTO MONDAY MORNING AND WE WILL RAISE POPS A LITTLE MORE. DEEP THETA-E ADVECTION ALONG WITH 30-40KTS LOW LEVEL JET SUPPORTS THE HIGHER PROBABILITIES AND WITH ENTRANCE REGION DYNAMICS TO AID IN ADDITIONAL LIFT. TEMPERATURES WILL BE MILD FOR THIS TIME OF THE YEAR WITH THE OFFICIAL START TO AUTUMN THIS WEEKEND. NOT TO WORRY AS THE CALENDAR WILL CATCH UP QUICKLY EARLY NEXT WEEK WITH FROPA EXPECTED BY MONDAY AFTERNOON AND COLD ADVECTION TO PERUSE. THE GFS SEEMS TO BE OVERDEVELOPED WITH THE CLOSED 500MB LOW AND WE PREFER THE MORE OPEN NATURE SIMILAR TO THE ECMWF/CANADIAN. THIS SHOULD KEEP THOSE NEGATIVE 850MB TEMPS A BIT IN CHECK (FOR NOW) ACROSS THE STATE BUT NEVERTHELESS LOWER SINGLE DIGIT READINGS EMBEDDED WITHIN THE CYCLONIC FLOW WILL PROVIDE UNSETTLED CONDITIONS THROUGH MID-WEEK WITH THE CHANCE FOR RAIN SHOWERS AND SOME LAKE EFFECT RAIN SHOWERS FROM LAKE MICHIGAN. THEN FOLLOWING THE ECMWF/CANADIAN IDEA OF BUILDING HEIGHTS AND SURFACE PRESSURES TOWARD THE END OF THE WEEK ACROSS THE NORTHERN PLAINS AND EVENTUALLY INTO THE GREAT LAKES REGION. HOWEVER...THIS WILL NOT BE A CLEAN FORECAST AS INDICATIONS ARE WE QUICKLY TRANSITION INTO A ZONAL FLOW WITH A FURTHER SOUTH POSITION OF THE MAIN UPPER JET. LIKELY SEE MORE CLOUDS BUT WILL REFRAIN FROM THE MENTION OF PRECIP AT THIS TIME. SUMMER IS INDEED COMING TO AN END. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ UPDATE.......BRAVENDER AVIATION.....DRC SHORT TERM...DRC LONG TERM....BGM 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 DETROIT/PONTIAC MI 750 AM EDT FRI SEP 15 2006 .AVIATION... DENSE FOG WAS CAUSING LIFR CONDITIONS AT MBS/FNT. A LOW STRATUS DECK OF ABOUT 1000-1500 HAS BEEN MOVING WESTWARD AND SOUTHWARD. THIS DECK HAS BEEN WIPING OUT FOG AS IT MOVES ALONG LEAVING DET/DTW WITH MVFR CEILINGS. AS THE DAY HEATS UP...THIS DECK SHOULD STOP EXPANDING AND BEGIN MIXING OUT THIS MORNING LEAVING GENERALLY SCT CONDITIONS. SOUNDINGS SHOWS SOME INSTABILITY IN LOW LEVELS SO COULD SEE OCCASSIONAL BKN 2500FT MVFR CEILINGS IN THE AFTERNOON... ESPECIALLY DET/DTW WHERE LOW LEVEL MOISTURE WILL BE A BIT MORE AVAILABLE. && .UPDATE... HEAT FLUX FROM STRATUS DECK HAS REALLY TAKEN A TOLL ON FOG DEVELOPMENT AND EXISTING DENSE FOG. VISIBILITIES IN AREAS WENT FROM LESS THEN A 1/4 MILE TO OVER 10 IN LESS THEN AN HOUR. LOW CLOUDS HAVE MADE IT TO ABOUT CARO IN TUSCOLA COUNTY SOUTH THROUGH PONTIAC TO DETROIT. LOOKS LIKE THE WESTWARD ADVANCEMENT IS SLOWING BUT SHOULD CONTINUE SOUTH. WILL DISCONTINUE DENSE FOG ADVISORY FROM WAYNE COUNTY ON NORTH AND EAST. && .SHORT TERM...TODAY AND TONIGHT SURFACE HIGH AND UPPER RIDGE WILL BE OVER HEAD TODAY AND TONIGHT. FORECAST PROBLEM WILL BE FOG AND CLOUD COVER THIS MORNING. LARGE SHIELD OF LOW STRATUS HAS BEEN WORKING BACK AROUND UPPER LOW SYSTEM OVER PENNSYLVANIA INTO THE EASTERN THUMB AND IS CONTINUING TO SPREAD SOUTH AND WESTWARD UNDER INVERSION. THIS IS ALSO BEING HELPED BY WEAK SURFACE TROUGHING EXTENDING BACK WEST INTO THUMB. GFS SEEMS TO HAVE THE BEST HANDLE ON THIS LOOKING AT THE 925-950MB MOISTURE FIELD. LOW CLOUDS WILL LIKELY MAKE IT NO FURTHER WEST THEN US23/US23/I75 LINE. WILL CONTINUE THE DENSE FOG ADVISORY UNTIL 14Z AS MOST OBSERVATIONS SHOWING VISIBILITIES 1/4 MILE OR LESS...EXCEPTIONS HAVE BEEN MOST OF WAYNE COUNTY WHERE URBAN HEAT ISLAND AFFECT SEEMS TO HAVE KEPT DEW POINT SPREAD APART FAR ENOUGH TO LIMIT FOG DEVELOPMENT SO FAR AND EASTERN MACOMB COUNTY WHERE CLOUD COVER HAS PREVENT DECENT RADIATIONAL COOLING. STILL SEVERAL HOURS TO GO BEFORE SUNRISE SO DO EXPECT SOME DEGREE OF FOG TO DEVELOP IN THESE AREAS BUT MORE OF PATCHY DENSE FOG THEN WIDESPREAD. FOG AND CLOUDS WILL MIX AND DISSIPATE OUT BY NOON. MODEL SOUNDINGS SHOW ENOUGH INSTABILITY AND LOW LEVEL MOISTURE ACROSS EASTERN PORTIONS OF CWA TO GENERATE SCT-BKN CU THIS AFTERNOON SO WILL CARRY PARTLY CLOUDY THOSE AREAS AND MOSTLY SUNNY ELSEWHERE. SHOULD HAVE CLEAR SKIES TONIGHT WITH OUT ANY LOW LEVEL CLOUD INTRUSION LIKE OVERNIGHT. EXPECT GOOD RADIATIONAL COOLING AGAIN TONIGHT SO WILL CARRY AREAS OF FOG. NOT EXPECTING WIDESPREAD DENSE FOG BUT WILL LIKELY SEE PATCHY DENSE FOG. WILL GO WITH WARMER GFS NUMBERS AS MET GUIDANCE UNDER DID YESTERDAYS HIGHS AND SEEMS A BIT LOW FOR TODAY. && .LONG TERM...SATURDAY THROUGH THURSDAY A BRIEF WARM UP THEN AUTUMN CONDITIONS SETTLE INTO THE GREAT LAKES FOR NEXT WEEK (BUT NOT AS EMPHATIC PER THE GFS). LARGE SCALE PATTERN SHIFT IS UNDERWAY WITH DEEP AND COLD TROUGH ACROSS THE PACIFIC NORTHWEST INTO THE FOUR CORNERS REGION AND SURFACE LEE-CYCLOGENESIS ACROSS THE WESTERN DAKOTAS. IN TURN THE DOWNSTREAM RIDGE CONTINUES TO AMPLIFY WITH STRENGTHENING SURFACE HIGH ACROSS THE MIDWEST AND TENNESSEE VALLEY THAT WILL REMAIN IN PLACE THROUGH SATURDAY. MODELS ARE CONSISTENT WITH OCCLUDED FRONT IN THE GREAT LAKES SUNDAY NIGHT INTO MONDAY MORNING. THE NMM/CANADIAN SUGGEST 500MB WAVE ON THE ENTRANCE SIDE OF THE JET WILL AMPLIFY AND TRACK INTO THE STATE LATE SUNDAY BUT CONSENSUS FROM THE GFS/ECMWF SUGGEST HOLDING OFF UNTIL SUNDAY NIGHT GIVEN STRENGTH OF UPSTREAM TROUGH AND TRENDS SUGGEST A LITTLE SLOWER PROGRESS. THIS CONTINUES WITH THE CHANCE FOR SHOWERS/THUNDERSTORMS SUNDAY NIGHT INTO MONDAY MORNING AND WE WILL RAISE POPS A LITTLE MORE. DEEP THETA-E ADVECTION ALONG WITH 30-40KTS LOW LEVEL JET SUPPORTS THE HIGHER PROBABILITIES AND WITH ENTRANCE REGION DYNAMICS TO AID IN ADDITIONAL LIFT. TEMPERATURES WILL BE MILD FOR THIS TIME OF THE YEAR WITH THE OFFICIAL START TO AUTUMN THIS WEEKEND. NOT TO WORRY AS THE CALENDAR WILL CATCH UP QUICKLY EARLY NEXT WEEK WITH FROPA EXPECTED BY MONDAY AFTERNOON AND COLD ADVECTION TO PERUSE. THE GFS SEEMS TO BE OVERDEVELOPED WITH THE CLOSED 500MB LOW AND WE PREFER THE MORE OPEN NATURE SIMILAR TO THE ECMWF/CANADIAN. THIS SHOULD KEEP THOSE NEGATIVE 850MB TEMPS A BIT IN CHECK (FOR NOW) ACROSS THE STATE BUT NEVERTHELESS LOWER SINGLE DIGIT READINGS EMBEDDED WITHIN THE CYCLONIC FLOW WILL PROVIDE UNSETTLED CONDITIONS THROUGH MID-WEEK WITH THE CHANCE FOR RAIN SHOWERS AND SOME LAKE EFFECT RAIN SHOWERS FROM LAKE MICHIGAN. THEN FOLLOWING THE ECMWF/CANADIAN IDEA OF BUILDING HEIGHTS AND SURFACE PRESSURES TOWARD THE END OF THE WEEK ACROSS THE NORTHERN PLAINS AND EVENTUALLY INTO THE GREAT LAKES REGION. HOWEVER...THIS WILL NOT BE A CLEAN FORECAST AS INDICATIONS ARE WE QUICKLY TRANSITION INTO A ZONAL FLOW WITH A FURTHER SOUTH POSITION OF THE MAIN UPPER JET. LIKELY SEE MORE CLOUDS BUT WILL REFRAIN FROM THE MENTION OF PRECIP AT THIS TIME. SUMMER IS INDEED COMING TO AN END. && .PREV DISCUSSION...ISSUED 100 AM EDT FRI SEP 15 2006 AVIATION... REDUCED VISIBILITIES IN FOG WILL BE A BIG AVIATION CONCERN THIS MORNING AS HIGH PRESSURE REMAINS CENTERED OVER THE STATE. CLEAR SKIES...LIGHT WINDS AND HIGH SOIL MOISTURE HAS SET THE STAGE FOR OPTIMAL RADIATIONAL FOG DEVELOPMENT THIS MORNING. WILL CONTINUE TO CARRY SEVERAL HOURS OF QUARTER MILE VISIBILITY AT FNT AND MBS. THE COMBINATION OF THE URBAN HEAT ISLAND AFFECT AND A LITTLE STRONGER NORTHERLY WINDS JUST ATOP THE NOCTURNAL INVERSION MAY BE ENOUGH TO PREVENT DENSE FOG AT DTW AND DET. AS OF 04Z...THERE IS A SOLID STRATUS DECK BASED AROUND 1200FT MOVING INTO MACOMB COUNTY. THE 00Z RUC NOW HAS THE BEST HANDLE ON THIS CLOUD COVER...WHICH BRINGS IT INTO DET BY 07Z. THE RUC DOES NOT SUGGEST MUCH ADDITIONAL WESTWARD MOVEMENT TO CLOUDS WITH THE LOW LEVEL WINDS FORECAST TO BE MORE NORTHERLY AT DETROIT. AT THIS POINT...WILL BRING THE STRATUS DECK INTO DET BUT HOLD OFF AT DTW. THE AFFECT OF THIS STRATUS DECK WILL BE TO REDUCE THE FOG DEVELOPMENT AND ALLOW SURFACE VISIBILITY TO INCREASE. BASED ON OBS IN WISCONSIN YESTERDAY AND GIVEN THE LOWER MID SEPTEMBER SUN ANGLE...FOG SHOULD NOT MIX OUT UNTIL 13-15Z. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...DENSE FOG ADVISORY...MIZ047-MIZ048-MIZ049-MIZ053-MIZ054-MIZ055- MIZ060-MIZ061-MIZ062-MIZ063-MIZ068-MIZ069-MIZ070-MIZ075- MIZ076-MIZ082-MIZ083 UNTIL 10 AM FRIDAY. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...DRC LONG TERM....BGM 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 GAYLORD MI 704 AM EDT FRI SEP 15 2006 .UPDATE...PER EARLIER DISCUSSION WILL CANCEL FOG ADVISORY EARLY FOR MBL/FRANKFORT/TVC. SUSPECT MOST OF WEXFORD IS IN DECENT SHAPE TOO...BUT WITH CAD AT 1/4SM AT THE MOMENT WILL LEAVE THAT ONE IN. NO OTHER CHANGES EXCEPT MINOR CLOUD COVER TWEAKS. && .PREV DISCUSSION ISSUED 500 AM FRI SEP 15... UPDATE...EXPANDING DENSE FOG ADVIS INTO OTSEGO. NO OTHER CHANGES. NOT WILLING TO GIVE UP ON HEADLINE YET WEST OF US-131...THOUGH TO THIS POINT TVC AND THE COAST HAVE NOT SEEN MUCH FOG YET. COULD CANCEL THOSE COUNTIES AROUND SUNRISE IF THINGS DO NOT CHANGE...STILL A COUPLE OF HOURS TO GO YET. JZ 03Z SURFACE/RUC ANALYSIS AND IR/WV IMAGERY SHOW A LARGE-SCALE TROUGH DIGGING OVER THE WEST COAST...AND A RELATIVELY FLATTENED RIDGE PARKED ACROSS THE MIDDLE CONUS. HIGH PRESSURE AT THE SURFACE CENTERED NE OF THE GEORGIAN BAY UNDER NORTHERLY FLOW ALOFT. THIS HIGH PRESSURE COMBINED WITH 500MB RIDGING WHOSE AXIS RUNS ALONG THE MISSISSIPPI RIVER VALLEY AND VERY DRY AIR ALOFT HAS ALLOWED FOR EXCELLENT RADIATIONAL COOLING CONDITIONS ACROSS THE CWA. THESE CONDITIONS HAVE HELPED WIDESPREAD FOG TO FORM ALREADY...MOSTLY CONFINED TO INLAND AREAS SOUTH OF M-32 AS NOTED BY OBS (ACB...3/4SM....GOV....1/2SM...HTL...1/4SM) AND 11U-3.9U SATELLITE IMAGERY. TEMPERATURES HAVE FALLEN INTO THE MIDDLE 40S TO LOWER 50S AND MOST PLACES ARE AT OR BELOW THEIR CROSSOVER TEMPS WITH THE EXCEPTION OF EASTERN UPPER. WITH NO PRECIP IN THE PICTURE UNTIL SUNDAY MORNING...MAIN FORECAST CONCERNS IN THE SHORT TERM REVOLVE AROUND FOG HEADLINES THIS MORNING. FOG HEADLINES....NOT SURPRISINGLY...FOG HAS BEEN ON THE INCREASE THIS MORNING AS TEMPS COOL. CURRENT OBS AND SATELLITE TRENDS SUPPORT KEEPING THE DENSE FOG ADVISORY GOING FOR AREAS SOUTH OF M-72. THE QUESTION IS WHETHER FOG WILL BECOME THICK ENOUGH OVER NORTHERN LOWER NORTH OF THIS LINE TO WARRANT HEADLINES? TEMPS HAVE FALLEN AT OR BELOW THE CROSSOVER TEMP FOR MANY LOCATIONS ACROSS THIS AREA BUT FOG HAS NOT FORMED NEARLY AS QUICK AS THEIR COUNTERPARTS TO THE SOUTH (07Z GLR JUST WENT 1/4SM FG BUT IS ONLY SITE NORTH OF M-72). WITH FURTHER COOLING TO TAKE PLACE THIS MORNING...EXPECT FOG TO BECOME MORE WIDESPREAD...BUT AM RELUCTANT TO CHANGE HEADLINES UNTIL MORE EVIDENCE BECOMES APPARENT FROM THE OBS. WILL HAVE TO KEEP AN EYE ON THINGS THROUGH THE EARLY MORNING HOURS. FOR THE REMAINDER OF TODAY...ANOTHER FANTASTIC DAY ON TAP...ONCE THE FOG LIFTS THIS MORNING. STRONG SUBSIDENCE AS NOTED BY THE 850-500MB RH 10 TO 20 PCT WILL PREVAIL WITH RIDGING AT THE SURFACE AND ALOFT. THIS SUBSIDENCE WILL INCREASE THROUGH THE DAY AS HEIGHT RISES TAKE PLACE WITH THE 500MB RIDGE STRENGTHENING AS IT PASSES OVERHEAD. ONCE THE FOG BURNS OFF THIS MORNING...LINGERING MOISTURE BELOW THE SUBSIDENCE INVERSION AS NOTED BY AN ACARS SOUNDING FROM APN (DEWPOINT 9C AT 925MB) LATE LAST EVENING WILL PROMOTE FLAT CU BUILD UP ESPECIALLY ACROSS THE HIGHER TERRAIN. WITH MIXING OF THE DRY AIR ABOVE...THIS CU WILL DIMINISH DURING THE MIDDLE OF THE AFTERNOON...LEAVING MOST LOCATIONS MOSTLY SUNNY. 850MB TEMPS INCREASE A DEGREE OR TWO...RANGING FROM 12-13C ACROSS NORTHERN LOWER...TO 13-14C OVER EASTERN UPPER...SO WE WILL SEE HIGHS MOSTLY IN THE MIDDLE 70S. THESE TEMPS...COMBINED WITH THE LIGHT WINDS WITH THE RIDGING...WILL PROMOTE LAKE BREEZES THIS AFTERNOON (950MB WINDS 5-10KTS NORTHERN LOWER AND 10-15KTS EASTERN UPPER)...AND WILL KEEP AREAS NEAR THE LAKES A FEW DEGREES COOLER. MPC LATER PERIODS...UPPER RIDGE AXIS WILL GRADUALLY SLIDE FROM THE CENTRAL TO THE EASTERN LAKES...AS AN IMPRESSIVE UPPER LOW GETS CARVED OUT IN THE NORTHERN PLAINS. QUIET WX LOOKS TO PREVAIL THRU SATURDAY...BUT A COLD FRONT WILL SLOWLY APPROACH FROM THE WEST FOR THE TAIL END OF THE WEEKEND. PRECIP CHANCES FROM SAT NIGHT ONWARD ARE THE MAIN CHALLENGE. MODELS...NAM IS RATHER FAST WITH THE COLD FRONT...NEARING LAKE MI BY SUNDAY MORNING. THE GFS STILL HAS THE BOUNDARY ON THE OTHER SIDE OF WI. SREF STARTS SLOW BUT ALMOST CATCHES UP WITH THE NAM...NGM (FOR WHAT IT/S WORTH) IS ALSO FAST...CANADIAN IS SLOW. NAM/GFS BOTH SHOWING GOOD CONSISTENCY. WILL LEAN TOWARD THE SLOW SIDE PER USUAL MODEL BIASES...BUT THAT STILL MEANS BRINGING IN RAIN FASTER THAN EARLIER FORECAST. TONIGHT/SATURDAY...WX CONCERNS FAIRLY MINIMAL. ANOTHER CLEAR AND STILL NIGHT TONIGHT WILL RESULT IN FOG. BUT SHOULD NOT BE AS MUCH FOG AS THIS MORNING...AFTER ANOTHER DAY OF GOOD DIURNAL MIXING AND WITH THE SURFACE HIGH MOVING EAST OF THE FORECAST AREA. WILL STAY TOWARD THE COOL END OF GUIDANCE TEMPS. MAY HAVE SOME CU/STRATOCU IN EASTERN UPPER MI SATURDAY...AS DEVELOPING SE SUB-900MB WINDS BRING IN SOME EXTRA MOISTURE OFF OF HURON. AND SOME CIRRUS WILL ARRIVE IN NORTHERN/WESTERN ZONES LATE. OTHERWISE...PLENTY OF SUNSHINE...WITH MAX TEMPS IN THE 70S...PERHAPS JUST TOUCHING 80 IN THE SOUTHERN ZONES (LIKE TVC...WHICH WILL BENEFIT FROM A DOWNSLOPING SOUTH WIND). SATURDAY NIGHT...DEVELOPING 850MB LOW LEVEL JET WILL PUNCH FROM KS INTO WI. THIS WILL BRING AN 850MB THETA-E RIDGE EAST WITH TIME...POKING INTO THE NORTHERN AND WESTERN ZONES LATE. INCREASING WARM/MOIST ADVECTION WILL SUPPORT A BAND OF SHOWERS (AND MAYBE AN EMBEDDED THUNDERSTORM) TRYING TO WORK ACROSS LAKE MI OVERNIGHT. INSTABILITY PROGS FROM EVEN THE AGGRESSIVE NAM DO NOT SUPPORT THUNDER THIS FAR EAST (ONLY 100-200 MUCAPE). BUT RAPID SATURATION OF THE MID AND LOW LEVELS AFTER 09Z MAY ALLOW SOME SHOWERS TO WORK IN FROM THE WEST. WILL HAVE A SMALL CHANCE OF PRECIP AFTER 08Z FROM CAD TO DE TOUR AND WEST. OTHERWISE...MID/HIGH CLOUDS WILL BE THICKENING EVERYWHERE...WITH DRY AIR BELOW 700MB PRECLUDING PRECIP. WILL BE A RELATIVELY WARM NIGHT WITH CLOUDS AND NO DECOUPLING...MIN TEMPS MAINLY UPPER 50S TO LOWER 60S. SUNDAY...850MB THETA-E RIDGE WILL TAKE IT/S TIME WORKING INTO AND ACROSS THE FORECAST AREA. FORCING/DYNAMICS ARE NOT ESPECIALLY IMPRESSIVE...AS THE LOW LEVEL JET DOES IT/S USUAL EARLY MORNING DECAY...AND UPSTREAM COLD FRONT WILL ONLY APPROACH LAKE MI TOWARD EVENING (AS LONG AS THE SLOWER SOLUTIONS HOLD). EXPECT A WEAKENING BAND OF SHOWERS TO PRESS FURTHER EAST IN THE MORNING BEFORE COMPLETELY FALLING APART. THEN IT FALLS TO HOW MUCH HEATING WE CAN SEE. WITH 850MB TEMPS +16/17C...MAX TEMPS WILL NEED TO BE NEAR 80 TO ALLOW SURFACE BASED INSTABILITY TO COOK OFF SOME STORMS. WE MIGHT GET THERE GIVEN THE EXPECTED MILD START TO THE DAY...BUT WITH A FAIR AMOUNT OF CLOUD COVER 80 IS PROBABLY THE TOP END. END RESULT...WILL HAVE A CHANCE OF SHRA MOST EVERYWHERE IN THE MORNING...AND ADD TSRA FOR THE AFTERNOON. WILL LEAVE PRECIP OUT NEAR SAGINAW BAY WHERE SURFACE RIDGING AND LOW LEVEL DRY AIR WILL TRY TO HANG ON THE LONGEST. REST OF THE FORECAST...WILL REMOVE THUNDER FROM EASTERN UPPER/NW LOWER MI MONDAY. COLD FRONT GOES THRU EARLY AND STRONG LOW LEVEL COLD ADVECTION IS WELL AHEAD OF THE COLD CORE ALOFT. WILL LEAVE THUNDER IN NE LOWER...THOUGH CURRENT PREFERRED TIMING SUGGEST EARLY MORNING WILL BE THE BEST SHOT THERE. WILL TREND TEMPS DOWNWARD A BIT MORE MONDAY AND ESPECIALLY TUESDAY...AS MODELS ARE CONSISTENT IN SHOWING A FAIRLY DRASTIC COLD SNAP FOR THIS TIME OF YEAR. (NOTE THE POSSIBILITY OF ACCUMULATING SNOW OVER THE WEEKEND IN THE MT/ND BORDER AREA. FOLKS...SUMMER IS ENDING.) ZOLTOWSKI && .APX...WATCHES/WARNINGS/ADVISORIES...DENSE FOG ADVISORY UNTIL 10 AM...MIZ022-027>030-032>036-041-042. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEWPORT/MOREHEAD CITY NC 1050 AM EDT FRI SEP 15 2006 .SHORT TERM /TODAY/...WRAPAROUND MOISTURE AND PRECIP AFFECTING THE NORTHEAST COUNTIES...OUTER BANKS AND COASTAL WATERS THIS MORNING. RUC AND 06Z GFS SHOWS LIGHT PRECIP POSSIBLE THROUGH THE DAY TODAY SO UPDATED ZONES TO INCLUDE 20 POPS IN THOSE AREAS. REMAINDER OF FORECAST UNCHANGED. && .AVIATION...IFR AND MVFR CIGS CONTINUE OVER ERN 2/3 OF AREA THIS MORNING. CONDITIONS EXPECTED TO IMPROVE MVFR/VFR THIS AFTN WITH HEATING. IFR STRATUS LIKELY AGAIN TONIGHT. && .MARINE...MINOR UPDATE TO DROP SCA HEADLINE OREGON INLET TO OCRACOKE AND TO ADJUST WINDS TO NW TO NE THIS MORNING ALL ZONES. SECONDARY LOW PRES INDICATED OFF OF CAPE LOOKOUT AND WINDS HAVE COME AROUND TO NW TO NE ALL WATERS THIS MORNING...FCST LOOKS GOOD FOR THIS AFTN. SEAS DOWN TO 5 FT AT DIAMOND SO SCA WAS ALLOWED TO EXPIRE. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...NONE. && $$ HSA/JBM nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA 245 PM PDT FRI SEP 15 2006 .SHORT TERM...LATEST SATELLITE IMAGERY ALONG WITH UPPER AIR RUC40 ANALYSIS NOW SHOWING THE TROF AXIS SHIFTING MORE INTO THE GREAT BASIN THIS AFTERNOON WITH A CONTINUE PUSH OF COOLER AIR INTO THE DISTRICT. WHILE MOISTURE REMAIN VERY MINIMAL TODAY...UPPER AIR ANALYSIS CONTINUES TO INDICATE THAT AN +80KT JET PUSHING INTO THE NORTHERN SECTIONS OF THE CWFA AND ALLOWING FOR BREEZY TO WINDY CONDITIONS OVER THE HIGHER TERRAIN AND ACROSS THE KERN DESERTS THIS EVENING. FURTHERMORE...WITH SURFACE PRESSURE GRADIENTS FROM SFO TO LAS WERE APPROACHING 16MB...LOWER ELEVATION WINDS COULD REACH THE 15 TO 20 MPH RANGE THROUGH SUNSET. IN ADDITION TO THE WINDS... CURRENT 24 HOUR TEMPERATURE CHANGE CHARTS CONTINUE TO SHOW AS MUCH AS 15 DEG-F OF COOLING FROM YESTERDAY AFTERNOON. THEREFORE...AS WINDS SUBSIDE OVERNIGHT ALONG WITH CLEAR SKIES...WILL SEE OVERNIGHT TEMPERATURES DROP TO NEAR RECORD LOWS AND MANY VALLEY LOCATIONS REACH DOWN INTO THE UPPER 40S TO LOWER 50S...WITH THE COOLER SPOT REACHING THE MID 40S. BY SATURDAY...WILL SEE A SLIGHT WARM UP AS 500MB HEIGHTS SLOWLY RISE BUT THE DISTRICT REMAINS UNDER A CYCLONIC FLOW. SO...WILL SEE A SURFACE PRESSURE GRADIENTS RELAX TO LOWER WINDS...BUT CONDITIONS WILL REMAIN COOL. LATEST FORECAST MODELS CONTINUE TO SHOW GOOD AGREEMENT WITH THIS SOLUTION OF SHIFTING THE TROF FARTHER EAST TOWARD SUNDAY AND ALLOWING HEIGHTS TO REBUILD OVER THE WEST COAST. RIDGING WILL BE MORE DOMINATE CLOSER TO SUNDAY AS BETTER WARMING WILL BEGIN. THIS WARMING TREND WILL CONTINUE THROUGH THE SHORT TERM AND INTO THE LONG TERM AS CLEAR SKIES CONTINUE. .LONG TERM...MONDAY NIGHT THROUGH FRIDAY...MODELS ARE STILL HAVE SOME DIFFICULTY HANDLING THE PATTERN AROUND MIDWEEK. THE PERIOD BEGINS WITH SHORT WAVE RIDGING SHIFTING EAST OVER THE INTERMOUNTAIN WEST MONDAY NIGHT AS AN UPPER TROUGH MOVES OVER THE PACNW. THIS TROUGH THEN SLIDES EAST OVER WESTERN MONTANA ON TUESDAY BRINGING A DRY NORTHWEST FLOW ALOFT OVER THE DISTRICT. AT THE SAME TIME A WEAK UPPER LOW DRIFTS EAST ALONG 30N TOWARDS THE SOCAL COAST. THE MODELS THEN WANT TO PHASE THESE TWO SYSTEMS TOGETHER MIDWEEK RESULTING IN AN AMPLIFIED UPPER TROUGH OVER THE WEST AND A STRONG UPPER RIDGE BUILDING OVER THE EPAC. THE GFS EVEN ENDS UP DEPICTING A CLASSIC REX BLOCK BY THURSDAY. BUT THE MAJORITY OF SOLUTIONS HAVE A LITTLE MORE PROGRESSIVE PATTERN WITH THE TROUGH INITIALLY AMPLIFYING OVER THE GREAT BASIN ON WEDNESDAY THEN SLOWLY SHIFTING EAST THROUGH FRIDAY. THERE WILL CERTAINLY BE SOME COOLING NEXT WEEK BUT GIVEN THE FLUCTUATING MODEL SOLUTIONS WILL REMAIN FAIRLY CONSERVATIVE WITH THIS TREND. HAVE SLIGHT COOLING EACH DAY THROUGH THURSDAY WITH HIGHS GENERALLY NEAR TO SLIGHTLY BELOW NORMAL. ALL MODELS ARE INDICATING LIMITED MOISTURE SO WILL KEEP A DRY FORECAST GOING. && .AVIATION...VFR CONDITIONS WILL PREVAIL THROUGH 00Z SUNDAY. FOR SPECIFIC DETAILS...PLEASE REFER TO TAFS FOR KMCE...KFAT AND KBFL AND TWEBS 421 AND 423. && .HNX WATCHES/WARNINGS/ADVISORIES...RED FLAG WARNING IN EFFECT UNTIL 8 PM PDT THIS EVENING. && $$ MOLINA/DCH ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA 945 AM PDT FRI SEP 15 2006 .SHORT TERM...LATEST SATELLITE IMAGERY ALONG WITH UPPER AIR RUC40 ANALYSIS INDICATES THAT THE TROF AXIS WAS STILL OVER THE WEST COAST WITH COOLER AIR CONTINUING TO PUSH IN BEHIND IT. WHILE MOISTURE WAS LACKING WITH THIS SYSTEM...MODELS SHOW A +80KT JET MAX PUSHING INTO THE NORTHERN SECTIONS OF THE CWFA TODAY WHICH WILL ALLOW FOR BREEZY TO WINDY CONDITIONS OVER THE HIGHER TERRAIN AND ACROSS THE KERN DESERTS. FURTHERMORE...WITH SURFACE PRESSURE GRADIENTS FROM SFO TO LAS AT AROUND 11MB...MAY SEE LOWER ELEVATION WINDS REACHING 10 TO 15 MPH THIS AFTERNOON. IN ADDITION TO THE WINDS...CURRENT 24 HOUR TEMPERATURE CHANGE CHARTS WERE SHOWING AS MUCH AS 15 DEG-F OF COOLING FROM YESTERDAY MORNING. AND...WITH TEMPERATURE PROFILERS SHOWING A DEEP COOL LAYER...IT WILL BE SLOW TO MIX OUT TO COOL AIR FOR AT LEAST 2 OR MAYBE 3 DAYS. THEREFORE...WILL SEE HIGHS OVER THE LOWER ELEVATIONS ONLY REACHING THE UPPER 70S AND SOME MOUNTAIN LOCATIONS REACHING INTO THE LOWER 60S. LATEST FORECAST MODELS REMAIN IN VERY GOOD AGREEMENT WITH SHIFTING THE TROF FARTHER EAST ON SATURDAY WHILE BEGINNING THE HEIGHT BUILDING PROCESS OVER THE WEST COAST. AS THIS OCCURS...THE WINDS WILL DROP OFF DRAMATICALLY OVERNIGHT AS A SURFACE HIGH BUILDS OVER THE GREAT BASIN. RIDGING IS STILL PROGGED TO CONTINUE SUNDAY AND A WARMING TREND WILL BEGIN. && .AVIATION...VFR CONDITIONS WILL PREVAIL THROUGH 12Z SATURDAY. FOR SPECIFIC DETAILS...PLEASE REFER TO TAFS FOR KMCE...KFAT AND KBFL AND TWEBS 421 AND 423. && .HNX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ MOLINA ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 330 PM EDT FRI SEP 15 2006 .SYNOPSIS... 18Z WATER VAPOR AND RUC ANALYSIS CONTINUE TO SHOW AN INCREASINGLY AMPLIFIED PATTERN ACROSS NORTH AMERICA. MOST PROMINENT FEATURE BEING THE LARGE CLOSED UPPER LOW CENTERED OVER EASTERN WASHINGTON AND THE ASSOCIATED H5 TROUGH COVERING MUCH OF THE PACIFIC COAST AND INTER-MOUNTAIN WEST. THE AMPLIFICATION OF THIS TROUGH IS FORCING DOWNSTREAM RIDGING ACROSS THE MISSISSIPPI...OHIO AND TENNESSEE VALLEY. OTHER FEATURES OF NOTE INCLUDE A WEAK H5 CLOSED LOW SPINNING ACROSS THE NORTHEASTERN STATES WITH AN ASSOCIATED TROUGH DOWN THE EAST COAST TO OUR FORECAST AREA. AT THE SURFACE...COLD FRONT HAS STALLED TO OUR SOUTH ACROSS THE CENTRAL FLORIDA PENINSULA. BEHIND THE FRONT THE DRY AIR IS MAKING ITS PUSH INTO THE FORECAST AREA FROM THE NORTH AND WEST. HIGH PRESSURE NOW CENTERED OFF TO THE NORTHWEST OF THE REGION WILL BE SETTLING SOUTHEAST TO PROVIDE A CALM...DRY...AND PLEASANT MID-SEPTEMBER WEEKEND TO MUCH OF THE SOUTHEAST. && .SHORT TERM...TONIGHT THROUGH MONDAY. THIS EVENING...DESPITE THE VERY DRY AIR ABOVE THE SURFACE...DPVA ASSOCIATED WITH WEAK SHORTWAVE CROSSING THE FORECAST AREA THIS AFTERNOON HAS PROVIDED JUST ENOUGH MID-LEVEL FORCING FOR AN ISOLATED SHOWER OR TWO (ONLY JUST PASSED OVER THE OFFICE IN TLH) EARLY IN THE EVENING...OTHERWISE SKIES WILL BECOME MOSTLY CLEAR NEAR OR JUST AFTER SUNSET. DECENT RADIATIONAL COOLING WILL ALLOW MOST INLAND LOCATIONS TO REACH THE MIDDLE AND UPPER 60S FOR THE PANHANDLE AND BIG BEND AREAS. AL/GA ZONES MAY EVEN BE A BIT COOLER WITH LOWER TO MIDDLE 60S COMMON. THE DEEP TROUGH AND ASSOCIATED UPPER LOW ACROSS THE WESTERN HALF OF THE CONUS WILL SLOWLY PUSH EAST THROUGH THE UPCOMING WEEKEND. THE DOWNSTREAM RIDGING SEEN ACROSS THE CENTRAL PART OF THE COUNTY WILL BE FORCED EAST REACHING THE ATLANTIC COAST BY SUNDAY. AS THIS OCCURS THE TROUGHING ALONG THE EAST COAST COAST WILL BE PUSHED OFFSHORE. THE RESULT WILL BE A HIGHLY AMPLIFIED PATTERN BY THE END OF THE WEEKEND WITH THE DEEP TROUGH FROM THE UPPER MIDWEST THROUGH THE CENTRAL PLAINS AND A LARGE H5 RIDGE FROM THE CENTRAL AND EASTERN GOMEX UP THE EAST COAST TO THE NEW ENGLAND STATES. AS ALL THIS IS OCCURRING...SURFACE HIGH PRESSURE CURRENTLY OVER THE OHIO AND TENNESSEE VALLEY WILL BE SINKING SOUTH AND EAST. THE HIGH CENTER IS FORECAST TO REACH THE CAROLINAS BY SATURDAY NIGHT AND THEN TRANSITION TO A POSITION NEAR THE SOUTHEAST COAST BY SUNDAY AFTERNOON. THE WEAK UPPER TROUGH CURRENTLY OVER OUR AREA MOVES OFF TO THE EAST THIS EVENING AND TAKES ANY LINGERING DYNAMICS/MOISTURE WITH IT. IN THIS TROUGHS WAKE...THE BUILDING UPPER RIDGE WILL SUPPLY PLENTY OF MID/UPPER LEVEL DRY AIR INTO AT LEAST MONDAY MORNING. PLENTY OF SUPPRESSION WILL EXIST WITH THE UPPER RIDGE AND ADVECTION OF DRY AIR TO KEEP POPS VERY LOW THROUGH THE WEEKEND. JUST THE OFF CHANCE OF A ISOLATED SHOWER ALONG THE SEABREEZE EACH AFTERNOON...BUT FEEL THE CHANCES/COVERAGE WILL BE LOW ENOUGH TO EXCLUDE FROM POP MENTION IN THE FORECAST. THE MOVEMENT OF THE SURFACE HIGH TO OUR NORTH AND THEN EAST WILL BRING LOW LEVEL FLOW AROUND FROM THE NORTHEAST TONIGHT AND EARLY SATURDAY TO THE SOUTHEAST AND SOUTH BY SUNDAY NIGHT AND EARLY MONDAY. WITH THIS RETURN FLOW FROM THE SOUTH AND SOUTHEAST BETWEEN THE HIGH TO OUR EAST AND AN APPROACHING FRONT DROPPING SOUTH THROUGH THE MISSISSIPPI AND TENNESSEE VALLEYS...MOISTURE WILL BE ON THE INCREASE AND BOTH THE NAM/GFS AGREE ON QUITE A BIT OF MID/UPPER LEVEL MOISTENING BY MONDAY AFTERNOON AND EVENING ALONG WITH THE BEGINNING OF A HEIGHT FALLS TREND THAT BECOMES MORE IMPRESSIVE MONDAY NIGHT. THIS MOISTURE ALONG WITH SOME MID/UPPER LEVEL DYNAMICS NEARBY TO THE WEST SHOULD ALLOW FOR MORE IN THE WAY OF AFTERNOON CONVECTION ACROSS MAINLY OUR WESTERN FLORIDA AND ALABAMA ZONES. .LONG TERM...MON NIGHT THROUGH THU. THE SURFACE HIGH DRIFTS EAST OFF THE GA COAST ON MONDAY...& A GRADUALLY INFLUX OF MOISTURE RETURNS TO THE CWA WITH SOUTH FLOW. THEN THE NEXT COLD FRONT IS EXPECTED TO PUSH ACROSS THE CWA ON TUESDAY...WITH A CHANCE OF SHOWERS & TSTMS. CURRENT MODELS PUSH THE FRONT OUT OF THE CWA BY WEDNESDAY MORNING...AS FLOW BECOME NW & A SURFACE HIGH BUILDS IN FROM THE NORTH. && .MARINE... WEAK STATIONARY FRONT WILL CONTINUE TO WASH OUT TO THE SOUTH OF THE REGION. HIGH PRESSURE WILL BUILD SOUTH FROM THE TENNESSEE VALLEY ACROSS THE WATERS THIS EVENING AND OVERNIGHT AND THEN REMAIN ACROSS THE FORECAST AREA THROUGH THE DAY ON SUNDAY. HIGH PRESSURE WILL PUSH OF THE SOUTHEAST COAST SUNDAY NIGHT AND MONDAY AS A COLD FRONT APPROACHES FROM THE NORTH AND WEST. THIS COLD FRONT IS FORECAST TO CROSS THE COASTAL WATERS LATER TUESDAY OR TUESDAY NIGHT. WINDS AND WAVES WILL GENERALLY REMAIN BELOW CAUTION LEVELS THROUGH THE WEEKEND...ALTHOUGH MAY BE LOCALLY HIGHER NEAR THE COAST EACH AFTERNOON WITH THE SEA BREEZE. WINDS AND SEAS WILL INCREASE FROM THE SOUTH MONDAY INTO TUESDAY AS THE GRADIENT TIGHTENS AHEAD OF THE APPROACHING FRONT AND MAY APPROACH CAUTION LEVELS AT TIMES. && .AVIATION... WE ARE LOOKING FOR MVFR VSBY TO DEVELOP ONCE AGAIN AFTER 06Z AT ABY AND VLD...THEN VFR CONDS THE REST OF TOMORROW WITH JUST SCT CU EXPECTED. && .FIRE WEATHER... A RIDGE OF HIGH PRESSURE WILL BUILD OVER THE REGION IN THE WAKE OF A COLD FRONT THAT PASSED THROUGH THE REGION ON THURSDAY. DRIER AIR AT THE SURFACE AND ALOFT WILL OVERSPREAD THE REGION CAUSING RELATIVE HUMIDITY VALUES IN THE AFTERNOON TO DROP TO NEAR CRITICAL LEVELS ON SATURDAY. THERE IS A SOMEWHAT LESSER CHANCE FOR RED FLAG CONDITIONS IN FLORIDA ON SUNDAY. MOISTURE WILL THEN INCREASE NEXT WEEK AHEAD OF A FRONT WHICH IS EXPECTED TO CROSS THE AREA ON TUESDAY. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 66 91 65 91 / 10 10 05 10 PANAMA CITY 70 89 71 90 / 10 05 10 10 DOTHAN 62 90 64 91 / 10 05 05 10 ALBANY 64 91 65 91 / 05 05 05 10 VALDOSTA 66 90 65 90 / 10 10 10 10 CROSS CITY 68 90 68 90 / 10 10 10 10 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...FIRE WX WATCH FROM SATURDAY AFTERNOON FOR THE FOLLOWING ZONES: CALHOUN...GADSDEN...HOLMES...INLAND WALTON...JACKSON...LEON... LIBERTY...WAKULLA...AND WASHINGTON. && $$ AVIATION...MCNATT PUBLIC...MROCZKA LONG TERM...TREXLER fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 358 PM EDT FRI SEP 15 2006 .DISCUSSION... FCST CONCERNS INCLUDE FOG POTENTIAL TONIGHT OVER CENTRAL AND ERN COUNTIES AND THEN PCPN CHANCES/TIMING THIS WEEKEND ALONG WITH TSRA POTENTIAL. WV IMAGERY AND RUC ANALYSIS INDICATED A TROF OVER THE WRN CONUS WITH A CLOSED MID/UPPER LEVEL LOW OVER THE PAC NW. DOWNSTREAM...A RDG EXTENDED FROM TX INTO THE GRT LAKES. AT THE SFC...A LOW WAS LOCATED OVER THE ERN DAKOTAS WITH A TROF EXTENDING THROUGH WRN NEBRASKA INTO THE TX PNDLE AND A FRONT FROM WRN ND INTO SE MANITOBA WHILE ANOTHER FRONT WAS LOCATED FROM WRN SD INTO SE WY AND CENTRAL CO. HIGH PRES PREVAILED OVER THE CNTRL GRT LAKES. A WAA SRLY FLOW HAS DEVELOPED OVER UPR MICHIGAN TODAY IN BETWEEN THE LOW PRES OVER THE DAKOTAS AND THE HIGH PRES OVER THE CENTRAL GREAT LAKES. MOSTLY SUNNY SKIES AND PLEASANT TEMPS IN THE MID 70S HAVE PREVAILED OVER MUCH OF UPR MI THIS AFTERNOON. TONIGHT...MODELS INDICATE SRLY BOUNDARY WINDS WILL STRENGTHEN TO OVERNIGHT TO 20 KT OVER WRN COUNTIES AHEDD OF SLOWLY APPROACHING FRONTAL SYSTEM FROM THE NRN PLAINS. THE ASSOCIATED MIXING FROM THE INCREASED WIND SHOULD PROHIBIT FOG FORMATION IN THE WEST. BASED ON WHAT HAPPENED LAST NIGHT...STILL HAVE SOME CONCERN THAT CENTRAL AND ERN COUNTIES COULD SEE SOME PATCHY FOG AIDED BY SSE UPSLOPE FLOW AND MOISTURE INFLUX FROM LAKE MICHIGAN. SFC ANALYSIS SHOWS DEWPOINTS QUITE MOIST OVER CENTRAL AND ERN COUNTIES (UPR 50S/LOW 60S) AND GIVEN THAT WINDS WILL BE LIGHTER IN THE EVENING OVER THIS AREA...HAVE ELECTED TO INCLUDE SOME PATCHY FOG OVERNIGHT. AREA. SAT...MDLS STILL INDICATE STRONG 850 MB THETA-E ADVECTION ALONG WITH THE POTENTIAL FOR WEAK SHRTWVS/Q-VECT CONV IN THE SW FLOW MAY SUPPORT SOME SHRA OR ISOLD TSTMS INTO MAINLY THE W THIRD OF UPR MI. KEPT IN ONLY LOWER END CHANCE POPS...GIVEN UNCERTAINTY WITH TIMING AND STRENGTH OF THE THE SHRTWVS. SINCE THE MORE UNSTABLE AIR WILL REMAIN W OF UPR MI...STRONG OR SVR STORMS ARE NOT EXPECTED. SAT NIGHT INTO SUN...THE NAM IS STILL SLIGHTLY FASTER WITH FRONTAL TIMING THAN THE GFS AND THE SLOWER UKMET. ALL MODELS SUGGEST POTENTIAL FOR SHRA/TSRA CHCS TO SPREAD E ACROSS THE FCST AREA SAT NIGHT IN WAA PATTERN AT NOSE OF 40KT H8 LLJ. SCT SHRA/TSRA SHOULD ALSO DEVELOP SUN ALONG AND AHEAD OF THE FRONT. MODELS NOT SHOWING A LOT IN WAY OF INSTABILITY ON SUN WITH MLCAPE VALUES OF 700-800 J/KG IN SW COUNTIES OFF GFS. HOWEVER...THERE IS GOOD DEEP LYR SHEAR TO SUPPORT POTENTIAL FOR STRONG TO SEVERE STORMS IF CLOUDS THIN OUT ENOUGH TO BOOST DAYTIME INSTABILITY. BEHIND THE FRONT MUCH OF AREA SHOULD GET INTO A DRY SLOT SUN NIGHT INTO MON MORNING WHICH WILL RESULT IN MOSTLY DRY CONDITIONS EXCEPT FOR MAYBE A FEW ISOLD SHRA. ALONG THE KEWEENAW PENINSULA...THERE COULD BE A BETTER CHC FOR SOME LAKE EFFECT SHRA IN WRLY FLOW. MON AFTERNOON THROUGH TUE...MODELS IN FAIRLY GOOD AGREEMENT DRIVING SHORTWAVE AND ASSOC COLD FRONT ACROSS THE FCST AREA. FAIRLY COLD AIR BEHIND THE FRONT (H8 TEMPS LOWER TO AROUND -2 TO -3C) WILL BRING INCREASED CHCS FOR LAKE EFFECT OR LAKE ENHANCED RAIN LATE MON INTO TUE WITH THE GREATEST CHCS FOR COUNTIES BORDERING LAKE SUPERIOR. EXTENDED...THE GFS ECMWF CANADIAN AND DGEX ARE IN GREAT AGREEMENT THROUGH 00Z WED. AT 12Z WED...THE GFS KEEPS A CLOSED 500MB LOW OVER EASTERN ONTARIO AND DEVELOPS A CLOSED LOW ACROSS WESTERN NEBRASKA. THE ECMWF BEGINS TO EJECT THE LOW INTO QUEBEC AND BUILDS A RIDGE AROSS THE WESTERN DAKOTAS. BOTH MODELS SHOW A TROUGH EXTENDING FROM THE GULF OF ALASKA THROUGH WESTERN MT. DESPITE THE UPPER LEVEL DIFFERENCES...BOTH MODELS SHOW A SFC RIDGE OVER THE SOUTHEAST US AND LOW PRESSURE DEVELOPING OVER THE WESTERN PLAINS BY 12Z WED AND REMAINING NEARLY STATIONARY THROUGH FRI. BOTH GFS AND ECMWF MODELS AGREE THERE WILL BE NW FLOW ACROSS LAKE SUPERIOR AFTER THE LOW PRESSURE SYSTEM GETS INTO QUEBEC 00Z TUE AND INTO NE CANADA 00Z THU...WITH THE ECMWF BEING SLIGHTLY MORE PROGRESSIVE. GFS HAS 850 TEMPS DOWN TO -6C AND THE ECMWF GETS DOWN TO -4C 12Z TUE. NW WINDS ACROSS THE LAKE WILL BE 15-25 KT AROUND 12Z TUE. WITH LAKE TEMPS AROUND 15C OUR CWA HAS A GOOD CHANCE OF LAKE EFFECT RAIN SHOWERS. WINDS DROP OFF FROM W TO E AFTER 00Z WED AND BEGIN TO BACK MORE WRLY...SO LAKE EFFECT SHOWERS WILL MOST LIKELY CEASE FOR MUCH OF THE FORECAST AREA. THE ECMWF BRINGS IN WARMER 850 TEMPS AROUND +2C BY 00Z THU WHILE THE GFS KEEPS TEMPS AROUND -4C. EVEN THOUGH HPC IS FAVORING GFS...SURROUNDING OFFICES ARE TRENDING TOWARD ECMWF/CANADIAN DAYS 4 TO 7. KEPT CHC RW- THROUGH 00Z WED THEN TAPERED OFF INTO SCHC BY WED MAINLY FOR AREAS ALONG THE LAKE SUPERIOR SHORE. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ VOSS (TONIGHT THROUGH TUE) MRE (EXTENDED WED-FRI) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 328 PM EDT FRI SEP 15 2006 .SHORT TERM...TONIGHT AND SATURDAY 12Z RAOBS/WATER VAPOR LOOP SHOW AN UPPER RIDGE OVER THE CENTRAL GREAT LAKES...BETWEEN A SMALL LOW OVER THE MID ATLANTIC COAST AND A LARGE LOW OVER THE PACIFIC NORTHWEST. SURFACE ANALYSIS SHOWS HIGH PRESSURE OVER LOWER MICHIGAN AND SOUTHEAST ONTARIO...WITH AN INCREASING SOUTHEASTERLY FLOW OVER THE WESTERN GREAT LAKES AHEAD OF THE NEXT LOW OVER THE WESTERN DAKOTAS. THE WESTERN LOW WILL SHIFT INLAND ACROSS THE NORTHERN HIGH PLAINS BY SATURDAY...CAUSING THE UPPER RIDGE TO FOLD DOWNSTREAM ACROSS THE LOWER GREAT LAKES. THE SURFACE HIGH WILL SLOWLY EDGE SOUTHEAST TOWARD ERIE/ONTARIO THROUGH 00Z SUNDAY. PERSISTENCE SEEMS TO BE THE KEY WORD FOR THE FORECAST TONIGHT. CU FIELD HAS MIXED OUT ACROSS THE THUMB AND SAGINAW VALLEY...BUT THICKER STRATUS HAS HELD FAST ACROSS THE SOUTHEAST CWA...GENERALLY SOUTH OF I-69 AND EAST OF US-23. 18Z/19Z TAMDAR SOUNDINGS CONTINUE TO SHOW NO BREAK IN THE LOW-LEVEL MOISTURE...WITH THE 18Z RUC FORECAST GETTING BETTER BUT THE 12Z NAM/GFS MUCH TOO DRY. WILL CARRY MOSTLY CLOUDY SKIES ACROSS THE SOUTHEAST CWA THROUGH THE EVENING. WILL GO PARTLY CLOUDY FOR A PERIOD OVERNIGHT...SIMILAR TO WHAT HAPPENED LAST NIGHT...EVEN THOUGH THESE CLOUDS DO NOT LOOK TOO DIURNAL. AM CONCERNED THAT WE WE MAY SEE ADDITIONAL CLOUDS EITHER PERSIST OR REDEVELOP...LIMITING DENSE FOG POTENTIAL AGAIN TONIGHT. WILL CARRY AREAS OF DENSE FOG...AND SEE HOW THE CURRENT STATUS FIELD EVOLVES BEFORE CONSIDERING ANY FOG ADVISORIES. DROPPED TEMPERATURES ACROSS THE NORTHWEST CWA WITH BETTER RADIATIONAL COOLING POTENTIAL WITH CLEARING SKIES...AND KEPT LOWS IN THE MID 50S ACROSS THE SOUTHEAST...SIMILAR TO LAST NIGHT. SURFACE HIGH WILL BE TO THE EAST OF THE CWA ON SATURDAY...WITH A WEAK SOUTHERLY/SOUTHEASTERLY PICKING UP BEHIND IT DURING THE DAY. 19Z TEMPERATURES UPSTREAM ACROSS WISCONSIN ARE GENERALLY IN THE MID 70S UNDER A HEALTHY CU FIELD. WILL DROP HIGHS A COUPLE DEGREES AND INCREASE SKY COVER...AS ANY MORNING FOG/STATUS SHOULD LIFT AND MIX INTO SCT/BKN CU ONCE AGAIN. && .LONG TERM...SATURDAY NIGHT THROUGH FRIDAY OVERALL FORECAST PHILOSOPHY HAS NOT CHANGED MUCH AS MODELS ARE IN RATHER GOOD AGREEMENT OF THE BREAKDOWN OF THE TRANSITORY UPPER RIDGE THAT WILL SET UP THIS WEEKEND. AS UPPER TROUGH OVER THE PACIFIC NW TOPS THE ROCKIES...A RATHER STRONG STORM SYSTEM WILL SPIN UP WITH THE RESULTANT SURFACE LOW TRACKING THROUGH THE NORTHERN LAKES AREA ON SUNDAY/MONDAY. THIS LOW WILL PUSH A COLD FRONT THROUGH LOWER MICHIGAN LATE SUNDAY NIGHT INTO MONDAY...WITH A DECENT CHANCE OF SHOWERS/THUNDERSTORMS EXPECTED WITH THIS FEATURE. IN ADDITION...MODELS SUGGEST A SURFACE TROUGH WILL ALSO MOVE INTO THE AREA IN ADVANCE OF THIS FRONT. THIS MAY PRODUCE A FEW SHOWERS/STORMS BY SUNDAY EVENING. WILL MAINTAIN THE MIDNIGHT SHIFTS ADJUSTMENT FOR THIS EARLIER TIMING THROUGH THE WESTERN PORTION OF THE CWA. AFTER THE COLD FRONT CLEARS THE AREA ON MONDAY...THE COLDEST AIR OF THE UPCOMING FALL SEASON WILL FILTER ACROSS THE AREA ON WEST WINDS. SUB ZERO H85 TEMPERATURES WILL REACH LAKE MICHIGAN AND THEN MODERATE AS THE AIR TRAVERSES THE LAKE INTO LOWER MICHIGAN. THIS WILL BE PLENTY COLD ENOUGH FOR LAKE EFFECT CLOUDS/SHOWERS AND WILL MAINTAIN THE DREARY/SHOWERY WEATHER ACROSS THE AREA MONDAY NIGHT ON INTO WEDNESDAY. THE TREND DURING THIS PERIOD WILL BE FOR SHOWERS TO BECOME MORE SPARSE ALONG THE SOUTHERN EDGE OF THE CWA AND WILL KEEP THIS IN THE FORECAST. REALLY THE ONLY CHANGE TO THE PRECIPITATION FORECAST WAS TO EXTEND THE "LULL" ON MONDAY AFTERNOON INTO THE EVENING AS IT WILL TAKE SOME TIME FOR THE LAKE EFFECT SHOWERS TO MOVE INTO THE AREA IN THE WAKE OF THE COLD FRONT AND ITS ATTENDING SHOWERS/THUNDERSTORMS. TEMPERATURES WILL TOP OUT IN THE LOWER 80S ON SUNDAY...AND THEN PERHAPS THE LOWER 70S ON MONDAY AS THE COLD FRONT MOVES THROUGH THE AREA. THEREAFTER...HIGHS WILL ONLY EDGE INTO THE LOWER 60S AT BEST TUESDAY/WEDNESDAY...WITH PERHAPS A SLIGHT MODERATION TO THE MID 60S ON THURSDAY/FRIDAY. FROM MONDAY NIGHT ON THROUGH THE REST OF THE WEEK...LOWS WILL RANGE IN THE 40S FOR THE MOST PART. MOSTLY CLOUDY SKIES AND A PERSISTENT WESTERLY FLOW MODERATED BY LAKE MICHIGAN WILL HELP STAVE OFF ANY WIDESPREAD 30S. MADE ONLY MINOR ADJUSTMENTS TO THE TEMPERATURES. && .PREV DISCUSSION...ISSUED 136 PM EDT FRI SEP 15 2006 AVIATION... FOG LAYER STATUS ACROSS THE SAGINAW VALLEY CONTINUES TO RAPIDLY MIX OUT...WHILE DEEPER LAYER STATUS ACROSS THE SOUTHEASTERN CWA AND SOUTHERN ONTARIO CONTINUES TO HOLD FAST. MBS HAS CLEARED OUT AND SHOULD ONLY SEE SCT/BKN CU FOR A COUPLE MORE HOURS. FNT IS ON THE LINE BETWEEN SCATTERED/MIXED CU AND THE SOLID DECK TO THE EAST...AND WILL CARRY PREDOMINATE MVFR CIGS INTO EARLY EVENING. DTW/DET ARE WELL INTO THE BETTER LOW-LEVEL MOISTURE APPARENT ON 16Z/17Z TAMDAR SOUNDINGS. 16Z RUC INITIALIZATION IS BETTER THAN EARLIER RUNS WITH THE LOW-LEVEL MOISTURE...BUT IS STILL ON THE DRY SIDE. AM CONCERNED THAT THE CLOUDS WILL LINGER ACROSS THE SOUTHERN CWA THROUGH THE NIGHT. WILL CARRY MVFR CIGS AT DTW/DET THROUGH LATE EVENING BEFORE SCATTERING OUT...SIMILAR TO LAST NIGHT. AS WELL AS WITH LAST NIGHT...WILL BRING IN AN MVFR/BORDERLINE IFR DECK LATE NIGHT...WITH MINIMAL FOG RESTRICTION AT DTW/DET. VISIBILITIES WILL BE LOWER AT FNT/MBS WITH LESS STATUS POTENTIAL TO INHIBIT FOG FORMATION. GIVEN SIMILAR FOG DEVELOPMENT UPSTREAM THIS MORNING AND WITH CONDENSATION PRESSURE DEFICITS OF ONLY A FEW MB ACROSS THE CWA BY 12Z TONIGHT... WILL HIT IFR/LIFR FOG AGAIN FOR A PERIOD AT FNT/MBS. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...BRAVENDER LONG TERM....DG AVIATION...BRAVENDER 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 DETROIT/PONTIAC MI 136 PM EDT FRI SEP 15 2006 .AVIATION... FOG LAYER STATUS ACROSS THE SAGINAW VALLEY CONTINUES TO RAPIDLY MIX OUT...WHILE DEEPER LAYER STATUS ACROSS THE SOUTHEASTERN CWA AND SOUTHERN ONTARIO CONTINUES TO HOLD FAST. MBS HAS CLEARED OUT AND SHOULD ONLY SEE SCT/BKN CU FOR A COUPLE MORE HOURS. FNT IS ON THE LINE BETWEEN SCATTERED/MIXED CU AND THE SOLID DECK TO THE EAST...AND WILL CARRY PREDOMINATE MVFR CIGS INTO EARLY EVENING. DTW/DET ARE WELL INTO THE BETTER LOW-LEVEL MOISTURE APPARENT ON 16Z/17Z TAMDAR SOUNDINGS. 16Z RUC INITIALIZATION IS BETTER THAN EARLIER RUNS WITH THE LOW-LEVEL MOISTURE...BUT IS STILL ON THE DRY SIDE. AM CONCERNED THAT THE CLOUDS WILL LINGER ACROSS THE SOUTHERN CWA THROUGH THE NIGHT. WILL CARRY MVFR CIGS AT DTW/DET THROUGH LATE EVENING BEFORE SCATTERING OUT...SIMILAR TO LAST NIGHT. AS WELL AS WITH LAST NIGHT...WILL BRING IN AN MVFR/BORDERLINE IFR DECK LATE NIGHT...WITH MINIMAL FOG RESTRICTION AT DTW/DET. VISIBILITIES WILL BE LOWER AT FNT/MBS WITH LESS STATUS POTENTIAL TO INHIBIT FOG FORMATION. GIVEN SIMILAR FOG DEVELOPMENT UPSTREAM THIS MORNING AND WITH CONDENSATION PRESSURE DEFICITS OF ONLY A FEW MB ACROSS THE CWA BY 12Z TONIGHT... WILL HIT IFR/LIFR FOG AGAIN FOR A PERIOD AT FNT/MBS. && .PREV DISCUSSION...ISSUED 1022 AM EDT FRI SEP 15 2006 UPDATE... VISIBILITIES CONTINUE TO LIFT ACROSS SOUTHEAST MICHIGAN...ENOUGH TO DROP THE FOG ADVISORY. ONLY LINGERING CONCERN IS ACROSS THE SAGINAW VALLEY. MBS HAS RECENTLY CLIMBED TO MVFR FOG...AN HOUR OR SO BEHIND HYX. THERE WILL BE SOME FOG LINGERING BETWEEN MBS AND MOP/AMN WHICH ARE STILL 1/4SM OR LESS...BUT A TIMING TO THIS EDGE SHOWS A SLOW AND STEADY WESTWARD PROGRESS. OTHERWISE VIS SATELLITE SHOWS THE MVFR STATUS THAT HELPED DISSIPATE THE FOG ACROSS THE EASTERN CWA IS HOLDING FAST. EXPECT THAT ANY THIN SPOTS IN THE CLOUDS WILL FILL IN SOON WITH CU...AND THAT THE STATUS ITSELF WILL TAKE ON A MORE CELLULAR/DIURNAL LOOK. MODELS CONTINUE TO HAVE A POOR HANDLE ON THE AMOUNT OF LOW-LEVEL MOISTURE ACROSS THE REGION...WITH 14Z TAMDAR SOUNDINGS OUT OF DTW NEARLY SATURATED BELOW 900MB...WHILE THE 14Z RUC INITIALIZATION SHOWS DEWPOINT DEPRESSIONS OF UP TO 7C IN THE SAME LAYER. NOT TOO MUCH DRY AIR ADVECTION EXPECTED...WITH CLOUD EROSION THROUGH MIXING INTO THE MUCH DRIER AIR ALOFT. WILL INCREASE SKY COVER...CARRYING MOSTLY CLOUDY THROUGH THE BULK OF THE DAY...ONLY CLOUDS ONLY BEGINNING TO MIX OUT BY LATE AFTERNOON. GIVEN THE EXPECTED DIURNAL TRANSITION FROM STATUS TO CU...CLOUDS SHOULD DIMINISH QUICKLY WITH SUNSET LEAVING MOSTLY CLEAR CONDITIONS AFTER 00Z. WILL ALSO DROP HIGH TEMPERATURES A FEW DEGREES GIVEN LIMITED INSOLATION. PREV DISCUSSION...ISSUED 750 AM EDT FRI SEP 15 2006 SHORT TERM...TODAY AND TONIGHT SURFACE HIGH AND UPPER RIDGE WILL BE OVER HEAD TODAY AND TONIGHT. FORECAST PROBLEM WILL BE FOG AND CLOUD COVER THIS MORNING. LARGE SHIELD OF LOW STRATUS HAS BEEN WORKING BACK AROUND UPPER LOW SYSTEM OVER PENNSYLVANIA INTO THE EASTERN THUMB AND IS CONTINUING TO SPREAD SOUTH AND WESTWARD UNDER INVERSION. THIS IS ALSO BEING HELPED BY WEAK SURFACE TROUGHING EXTENDING BACK WEST INTO THUMB. GFS SEEMS TO HAVE THE BEST HANDLE ON THIS LOOKING AT THE 925-950MB MOISTURE FIELD. LOW CLOUDS WILL LIKELY MAKE IT NO FURTHER WEST THEN US23/US23/I75 LINE. WILL CONTINUE THE DENSE FOG ADVISORY UNTIL 14Z AS MOST OBSERVATIONS SHOWING VISIBILITIES 1/4 MILE OR LESS...EXCEPTIONS HAVE BEEN MOST OF WAYNE COUNTY WHERE URBAN HEAT ISLAND AFFECT SEEMS TO HAVE KEPT DEW POINT SPREAD APART FAR ENOUGH TO LIMIT FOG DEVELOPMENT SO FAR AND EASTERN MACOMB COUNTY WHERE CLOUD COVER HAS PREVENT DECENT RADIATIONAL COOLING. STILL SEVERAL HOURS TO GO BEFORE SUNRISE SO DO EXPECT SOME DEGREE OF FOG TO DEVELOP IN THESE AREAS BUT MORE OF PATCHY DENSE FOG THEN WIDESPREAD. FOG AND CLOUDS WILL MIX AND DISSIPATE OUT BY NOON. MODEL SOUNDINGS SHOW ENOUGH INSTABILITY AND LOW LEVEL MOISTURE ACROSS EASTERN PORTIONS OF CWA TO GENERATE SCT-BKN CU THIS AFTERNOON SO WILL CARRY PARTLY CLOUDY THOSE AREAS AND MOSTLY SUNNY ELSEWHERE. SHOULD HAVE CLEAR SKIES TONIGHT WITH OUT ANY LOW LEVEL CLOUD INTRUSION LIKE OVERNIGHT. EXPECT GOOD RADIATIONAL COOLING AGAIN TONIGHT SO WILL CARRY AREAS OF FOG. NOT EXPECTING WIDESPREAD DENSE FOG BUT WILL LIKELY SEE PATCHY DENSE FOG. WILL GO WITH WARMER GFS NUMBERS AS MET GUIDANCE UNDER DID YESTERDAYS HIGHS AND SEEMS A BIT LOW FOR TODAY. LONG TERM...SATURDAY THROUGH THURSDAY A BRIEF WARM UP THEN AUTUMN CONDITIONS SETTLE INTO THE GREAT LAKES FOR NEXT WEEK (BUT NOT AS EMPHATIC PER THE GFS). LARGE SCALE PATTERN SHIFT IS UNDERWAY WITH DEEP AND COLD TROUGH ACROSS THE PACIFIC NORTHWEST INTO THE FOUR CORNERS REGION AND SURFACE LEE-CYCLOGENESIS ACROSS THE WESTERN DAKOTAS. IN TURN THE DOWNSTREAM RIDGE CONTINUES TO AMPLIFY WITH STRENGTHENING SURFACE HIGH ACROSS THE MIDWEST AND TENNESSEE VALLEY THAT WILL REMAIN IN PLACE THROUGH SATURDAY. MODELS ARE CONSISTENT WITH OCCLUDED FRONT IN THE GREAT LAKES SUNDAY NIGHT INTO MONDAY MORNING. THE NMM/CANADIAN SUGGEST 500MB WAVE ON THE ENTRANCE SIDE OF THE JET WILL AMPLIFY AND TRACK INTO THE STATE LATE SUNDAY BUT CONSENSUS FROM THE GFS/ECMWF SUGGEST HOLDING OFF UNTIL SUNDAY NIGHT GIVEN STRENGTH OF UPSTREAM TROUGH AND TRENDS SUGGEST A LITTLE SLOWER PROGRESS. THIS CONTINUES WITH THE CHANCE FOR SHOWERS/THUNDERSTORMS SUNDAY NIGHT INTO MONDAY MORNING AND WE WILL RAISE POPS A LITTLE MORE. DEEP THETA-E ADVECTION ALONG WITH 30-40KTS LOW LEVEL JET SUPPORTS THE HIGHER PROBABILITIES AND WITH ENTRANCE REGION DYNAMICS TO AID IN ADDITIONAL LIFT. TEMPERATURES WILL BE MILD FOR THIS TIME OF THE YEAR WITH THE OFFICIAL START TO AUTUMN THIS WEEKEND. NOT TO WORRY AS THE CALENDAR WILL CATCH UP QUICKLY EARLY NEXT WEEK WITH FROPA EXPECTED BY MONDAY AFTERNOON AND COLD ADVECTION TO PERUSE. THE GFS SEEMS TO BE OVERDEVELOPED WITH THE CLOSED 500MB LOW AND WE PREFER THE MORE OPEN NATURE SIMILAR TO THE ECMWF/CANADIAN. THIS SHOULD KEEP THOSE NEGATIVE 850MB TEMPS A BIT IN CHECK (FOR NOW) ACROSS THE STATE BUT NEVERTHELESS LOWER SINGLE DIGIT READINGS EMBEDDED WITHIN THE CYCLONIC FLOW WILL PROVIDE UNSETTLED CONDITIONS THROUGH MID-WEEK WITH THE CHANCE FOR RAIN SHOWERS AND SOME LAKE EFFECT RAIN SHOWERS FROM LAKE MICHIGAN. THEN FOLLOWING THE ECMWF/CANADIAN IDEA OF BUILDING HEIGHTS AND SURFACE PRESSURES TOWARD THE END OF THE WEEK ACROSS THE NORTHERN PLAINS AND EVENTUALLY INTO THE GREAT LAKES REGION. HOWEVER...THIS WILL NOT BE A CLEAN FORECAST AS INDICATIONS ARE WE QUICKLY TRANSITION INTO A ZONAL FLOW WITH A FURTHER SOUTH POSITION OF THE MAIN UPPER JET. LIKELY SEE MORE CLOUDS BUT WILL REFRAIN FROM THE MENTION OF PRECIP AT THIS TIME. SUMMER IS INDEED COMING TO AN END. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....BRAVENDER UPDATE.......BRAVENDER SHORT TERM...DRC LONG TERM....BGM 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 HASTINGS NE 222 PM CDT FRI SEP 15 2006 .SHORT TERM...THIS EVENING THROUGH SUNDAY NIGHT. PRIMARY FORECAST CONCERN WILL REVOLVE AROUND THE CHANCE FOR STRONG TO SEVERE THUNDERSTORMS THIS EVENING AND POSSIBLE REDEVELOPMENT OVER FAR EASTERN ZONES TOMORROW AFTERNOON. WATER VAPOR IMAGERY SHOWS A LARGE TROUGH DIGGING OVER THE WESTERN CONUS WITH UPPER AIR OBSERVATIONS DEPICTING A 90 TO 100 KT JET LEVEL SPEED MAX OVER THE DESERT SOUTHWEST. FAVORABLE LEFT EXIT REGION OF THE JET IS LOCATED OVER NEBRASKA. A 994 MB SFC LOW IS POSITIONED OVER THE WESTERN DAKOTAS EARLY THIS AFTERNOON WITH A 1020MB HIGH SITUATED OVER SOUTHEAST MISSOURI. THE SUBSEQUENT TIGHT PRESSURE GRADIENT ACROSS THE PLAINS... AND AMPLE MIXING UNDER PARTLY TO MOSTLY SUNNY SKIES...HAS DRIVEN SOUTH WINDS UP INTO THE 20 TO 30MPH RANGE THIS AFTERNOON. THE STRONG SOUTHERLY FLOW HAS ALSO HELPED TO DRIVE DEWPOINTS OUT OF THE LOWER 50S THIS MORNING TO AROUND 60 THIS AFTERNOON. THE INITIAL CONCERN FOR LATE THIS AFTERNOON AND EARLY THIS EVENING REVOLVES AROUND THE POSSIBILITY OF SFC BASED CONVECTION ACROSS OUR WESTERN CWA. SFC HEATING UNDER MOSTLY SUNNY SKIES...ALONG WITH ENHANCED SFC CONVERGENCE ACROSS SOUTHWEST NEBRASKA IS NOW RESULTING IN THE DEVELOPMENT OF A CUMULUS FIELD EXTENDING FROM MCK TO LBF TO TIF. THIS AREA OF ENHANCED CONVERGENCE WILL SLOWLY SHIFT EAST INTO OUR CWA LATER THIS AFTERNOON AND THIS EVENING ACTING AS A FOCAL POINT FOR CONVECTIVE DEVELOPMENT. THE RUC AND GFS ARE STILL FORECASTING HIGH CIN VALUES FOR THIS EVENING WHICH WOULD MAKE SFC BASED CONVECTION MORE DIFFICULT TO ACHIEVE. THE NAM WOULD BE MORE SUPPORTIVE OF SEEING A FEW SFC BASED STORMS. OVERALL FEELING IS THAT MOST OF THE THUNDERSTORMS THIS AFTERNOON AND EVENING WILL REMAIN ELEVATED ESPECIALLY OVER EASTERN AND CENTRAL ZONES...MAKING DAMAGING WINDS AND LARGE HAIL THE PRIMARY THREATS. DEEP LAYER SHEAR OF CLOSE TO 40KTS WITH MLCAPE VALUES OF 1500 J/KG WILL SUPPORT THE POSSIBILITY OF SEVERE THUNDERSTORMS. A STRONG 50 TO 60KT LOW LEVEL JET WILL CONTINUE TO FEED THUNDERSTORMS AFTER DARK WITH STORMS TRACKING NORTHEAST ACROSS OUR CWA. THUNDERSTORMS SHOULD EXIT OUR CWA AFTER MIDNIGHT TONIGHT WITH DECREASING CLOUDS FROM WEST TO EAST BY DAYBREAK. A PREFRONTAL SFC TROUGH AND COLD FRONT WILL BOTH TRACK ACROSS OUR CWA DURING THE DAY ON SATURDAY. TEMPERATURES WILL STILL RISE INTO THE 80S AS THE COLD AIR WILL TAKE A WHILE TO FILTER INTO THE REGION. SEVERE THUNDERSTORMS WILL LIKELY REDEVELOP ALONG THE PREFRONTAL TROUGH SATURDAY AFTERNOON...BUT THIS WILL LIKELY NOT OCCUR UNTIL THE TROUGH IS EAST OF OUR CWA OR JUST EXITING OUR EASTERN MOST COUNTIES. SFC COLD FRONT WILL QUICKLY FOLLOW BEHIND THE INITIAL TROUGH WITH EVERYTHING THROUGH OUR CWA BY TOMORROW EVENING. GIVEN THIS TIMING...MOST OF OUR CWA WILL REMAIN DRY ON SATURDAY WITH JUST A SLIGHT CHANCE OF THUNDERSTORMS OVER OUR FAR EASTERN CWA. ANY THUNDERSTORMS THAT DEVELOP ALONG OUR EASTERN CWA FROM YORK TO HEBRON WILL STAND THE CHANCE OF BECOMING SEVERE THANKS TO STRONG WIND SHEAR AND MODERATE INSTABILITY. NOTICEABLY COOLER AIR THEN FILTERS INTO THE REGION ON SUNDAY AS SFC HIGH PRESSURE BUILDS IN MAKING FOR A DRY BUT COOL DAY. .LONG TERM...MONDAY THROUGH FRIDAY. THE BEGINNING OF THE EXTENDED PERIOD WILL BE UNDER THE INFLUENCE OF THE UPPER TROUGH OF LOW PRESSURE WHICH WILL HAVE JUST PASSED TO OUR EAST SUNDAY NIGHT. HEIGHTS WILL BEGIN TO RISE BEHIND THE DEPARTING SYSTEM...BUT THE AIRMASS WILL REMAIN RATHER COOL FOR MUCH OF THE WEEK. READINGS MODERATE JUST SLIGHTLY ON TUESDAY...THEN MODELS DIVERGE IN HANDLING OF PATTERN FROM MID WEEK ON. THE 06Z GFS SUGGESTED NEXT CLOSED LOW WILL SLIP SOUTHEAST THRU OUR CWA TUESDAY NIGHT OR WEDNESDAY BRINGING ANOTHER CHANCE OF PCPN. THE 12Z GFS TAKES PART OF THIS NEXT PIECE OF ENERGY TO OUR NORTH...BUT STILL DIGS A TROUGH OVER THE ROCKIES...THEN SWINGS A WEAKER TROUGH THRU THURS NIGHT OR FRIDAY...WITH MAIN PCPN SETTING UP TO OUR SOUTH. THE ECMWF ALSO SUGGESTS A TROUGH OVER THE MOUNTAINS...BUT MAIN DEEPER CLOSED LOW REMAINING TO OUR NORTH. THE 12Z GFS IS MORE SIMILAR TO THE ECMWF...AND THE CANADIAN FALLS IN BETWEEN THIS. GIVEN THE DIFFERENCES IN TIMING AND PLACEMENT OF THIS NEXT SYSTEM...HAVE LEFT THE EXTENDED FORECAST DRY. TEMPERATURES OVERALL WILL GENERALLY BE BELOW SEASONAL NORMALS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ WESELY ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 425 PM EDT FRI SEP 15 2006 .SYNOPSIS... THE UNSETTLED WEATHER WILL CONTINUE A LITTLE LONGER, AND UNFORTUNATELY FOR THE START OF THE WEEKEND. THIS IS ALL COURTESY OF A SLOW MOVING UPPER LEVEL LOW, WHICH IS EXPECTED TO FINALLY EXIT STAGE RIGHT-ISH (SOUTHEAST) DURING SATURDAY. THIS WILL SET UP FOR A NICE FINISH TO THE WEEKEND AS WARMER AIR IS EXPECTED TO SURGE INTO THE REGION, PARTICULARLY FOR THE EARLY PART OF NEXT WEEK. A COLD FRONT THOUGH IS SCHEDULED TO CROSS THE REGION TUESDAY, FOLLOWED BY A SHOT OF MUCH COOLER AIR. THE COOLER AIR WILL LAST FOR SEVERAL DAYS NEXT WEEK, HOWEVER AS HIGH PRESSURE GRADUALLY BEGINS TO SETTLE TO THE EAST ON FRIDAY, THE AIRMASS SHOULD MODIFY SOME. && .NEAR TERM /TONIGHT/... I APOLOGIZE FOR THE LATENESS OF THIS DISCUSSION. A RATHER COMPLEX SCENARIO UNFOLDED TODAY ACROSS OCEAN AND MONMOUTH COUNTIES IN NEW JERSEY, WITH OCEAN COUNTY BEING HIT VERY HARD. A DEEP EASTERLY FLOW, SOME SORT OF INVERTED SURFACE TROUGH, A SURGE OF THETA-E AND A SHORT WAVE RIDING AROUND THE EAST SIDE OF THE UPPER LOW, HELPED TO FOCUS TORRENTIAL RAINFALL IN THE ABOVE AREAS. A SURFACE ANALYSIS EARLIER THIS MORNING INDICATED THE PRESENT OF A MESO-LOW OVER SOUTHEASTERN NEW JERSEY WHICH MIGHT HAVE SPUN NORTHBOUND INTO THE OCEAN COUNTY AREA. THE KDIX 88D VELOCITY DATA SHOWED SOME SORT OF A BOUNDARY ACROSS EASTERN NEW JERSEY WITH STRONG CONVERGENCE. THE VELOCITY HAD A 'S-SHAPE' TO IT INDICATING SOME WAA AS WELL. ALL OF THIS COMBINED, APPEARED TO BE THE CAUSE OF THE EXCESSIVE RAINFALL. THE MILLION DOLLAR QUESTION FOR TONIGHT IS WHAT WILL THE EXTENT OF PRECIPITATION BE. AS FOR SOME OF THE MODEL GUIDANCE, THE NAM IS SLIGHTLY DEEPER AND MORE CLOSED OFF THAN THE GFS WITH THE MIDLEVEL VORTEX AND LESS PROGRESSIVE. SURFACE DIFFERENCES ARE ESPECIALLY PRONOUNCED WITH THE NAM DEEPER AND MUCH FARTHER WEST WITH THE MAIN SURFACE LOW OVER THE ATLANTIC, WITH A MORE ORGANIZED CIRCULATION. IT WAS DECIDED TO LEAN MORE TOWARD THE GFS, ALTHOUGH IT SHOULD BE NOTED THE RUC EARLIER HAD THE BULLSEYE OF RAIN IN THE CORRECT LOCATION. THE 00Z/15 ECMWF, 09Z/15 SREF MEAN, AND THE 12Z/15 CANADIAN REGIONAL MODEL ALL SHOW PRONOUNCED SURFACE RIDGING EAST OF THE NEW JERSEY COAST IN 36 HOURS LIKE THE GFS. FOR A COUPLE OF DAYS NOW, THE NAM SEEMS TO HAVE BEEN BIASED TOWARD ITS SLOWER, DEVELOPED SOLUTION. AS A RESULT, WE WILL RUN WITH LIKELY POPS UP NORTH ALONG WITH AN ISOLATED THUNDER THIS EVENING AS ACTIVITY APPROACHING NYC WORKS WESTWARD THIS EVENING. WE THEN TAPERED THE POPS THROUGH CHC CATEGORY SOUTHWARD THIS EVENING BUT MOVED THE ISOLATED THUNDER MENTION TO COVER A GOOD PORTION OF THE CWA. SOME BREAKS OF SUNSHINE OCCURRING LATE THIS AFTERNOON ACROSS SOUTHERN NEW JERSEY AND MOVING INTO FAR SOUTHEASTERN PENNSYLVANIA. THEREFORE WITH THE UPPER-LOW OVERHEAD, ANY ADDED SUNSHINE MAY POP A THUNDERSTORM. IT APPEARS THEY WILL NOT GET ROBUST ENOUGH TO PRODUCE HAIL, PROBABLY JUST HEAVIER DOWNPOURS. EVEN WITH THE BREAKS IN THE CLOUDS OCCURRING LATE THIS AFTERNOON, WE THINK CLOUD COVERAGE TONIGHT SHOULD BE IN THE MOSTLY CLOUDY CATEGORY. WITH THE MOISTURE AROUND OVERNIGHT, DECIDED TO ADD IN AREAS OF FOG ACROSS THE AREAS THAT SAW THE HEAVIER RAIN, AND WENT WITH PATCHY FOG ELSEWHERE. AS FOR TEMPERATURES, WENT WITH A BLEND OF THE MAV/MET GUIDANCE. && .SHORT TERM /SATURDAY THROUGH MONDAY/... THIS TIME FRAME STARTS OUT RATHER TRICKY AS THE CUTOFF UPPER LOW WILL BE EASING SOUTHEASTWARD DURING SATURDAY. THE MODELS OVERALL AGREE IN THE EVOLUTION OF THE UPPER LOW SATURDAY, HOWEVER SOME OF THE DETAILS ARE A BIT UNCERTAIN. GIVEN THE SLOW NATURE OF THIS SYSTEM, WE WILL NOT RUSH THE LIFTING OUT OF IT. WENT WITH A LOW CHC POP FOR MORNING SHOWERS ACROSS THE REGION AS THE UPPER LOW SHOULD BE DRIFTING SOUTHWARD SATURDAY MORNING INTO THE DELMARVA. THIS WILL ALLOW THE WINDS TO SHIFT MORE TO THE NORTH, LIMITING THE INFLOW MOISTURE AND WEAKENING FRONTOGENETIC FORCING. AM ENVISIONING SOME LINGERING SHOWERS AND PERHAPS POCKETS OF DRIZZLE SATURDAY MORNING, BUT AS THE SYSTEM GRADUALLY STARTS TO BE MORE PROGRESSIVE DURING THE AFTERNOON, SOME MIDLEVEL RIDGING TRIES TO BUILD IN FROM THE WEST. BUFKIT SOUNDINGS DO SHOW SOME DRYING OCCURRING THROUGH THE DAY SATURDAY, WITH CLOUD BASES RISING. THEREFORE WE WILL TREND TO AT LEAST INDICATE SOME CLEARING ACROSS THE REGION DURING THE AFTERNOON. CONFIDENCE IN THE CLOUD COVER FOR SATURDAY IS NOT TO HIGH, BUT THERE APPEARS TO BE SOME SUNSHINE IN THE PICTURE. GRADUALLY RIDGING WILL BUILD INTO OUR REGION WITH A WARMING TREND ON SUNDAY. THE SECOND HALF OF THE WEEKEND IS EXPECTED TO BE MUCH BETTER. SOUTHWESTERLY FLOW TAKES OVER DURING THE COURSE OF SUNDAY AFTERNOON AND MONDAY, ALLOWING WAA TO OCCUR/CONTINUE. THIS WILL BOOST DAYTIME TEMPERATURES INTO THE 80S FOR MANY LOCALES. THE IMPROVED WEATHER IS NOT EXPECTED TO LAST TOO LONG AS MODEL GUIDANCE HITTING THE NEXT FRONTAL PASSAGE FAIRLY WELL. THIS COLD FRONT IS FORECAST TO BE LOCATED IN THE EASTERN GREAT LAKES TO OHIO VALLEY MONDAY. MOST OF THE REGION SHOULD START OUT MONDAY WITH A GOOD AMOUNT OF SUNSHINE, BUT GRADUALLY AN INCREASE IN CLOUDS IS ANTICIPATED, PARTICULARLY MONDAY NIGHT AS WAA INCREASES AND THE FRONTAL BOUNDARY NEARS THE WESTERN ZONES LATE. AS FOR TEMPERATURES, WENT WITH A BLEND OF THE MAV/MET GUIDANCE ALTHOUGH THEY WERE NOTED TO NOT BE TO DIFFERENT FOR MOST AREAS. && .LONG TERM /TUESDAY THROUGH FRIDAY/... GENERALLY FOLLOWED HPC GUIDANCE WITH MOSTLY SOME MINOR ADJUSTMENTS FOR LOCAL EFFECTS AND TIMING. THE 06Z GFS, WHILE SIMILAR THROUGH TUESDAY, BEGINS TO DIFFER QUITE A BIT FROM THE OPERATIONAL GFS/ECMWF AND EVEN THE GFS/ECMWF MEANS WHICH ARE SIMILAR. THE 06Z GFS TAKES THE PROGRESSIVE SHORT WAVE THAT THE OPERATIONAL GFS AND CANADIAN BRING TOWARD THE LOWER NORTHERN PLAINS LATE WEDNESDAY AND THURSDAY, MUCH FARTHER SOUTHWARD THROUGH THE CENTRAL TO LOWER MISSISSIPPI VALLEY, MEANWHILE UPSTREAM ADDITIONAL SHORT WAVE ENERGY IS TAKEN DEEP INTO OKLAHOMA AND TEXAS THURSDAY AND FRIDAY. THIS SOLUTION RESULTS IN A FULLY PHASED FULL LATITUDE TROUGH FROM LABRADOR TO TEXAS. THIS SCENARIO IS ENTIRELY DIFFERENT FROM THE OPERATIONAL GFS AND ECMWF AND ALSO THE 00Z GFS ENSEMBLE MEAN. PER HPC DISCUSSIONS, TELECONNECTIONS BASED ON A STRONG POSITIVE ANOMALY NEAR 70 NORTH/95 WEST DOES NOT YIELD MUCH OF A WESTERN U.S. TROUGH FOR THIS TIME OF YEAR. HOWEVER, WHEN THE TIME BASIS IS ADJUSTED FORWARD A MONTH TO MID OCTOBER, A NEGATIVE HEIGHT ANOMALY AND TROUGH DOES APPEAR OVER THE WESTERN U.S. WITH THE CONSISTENT OVERALL TREND OF LOWER HEIGHTS AND SOUTHWARD DISPLACED WESTERLIES OVER NORTH AMERICA, IT APPEARS TO BE MORE LIKE MID TO LATE OCTOBER THEN MID SEPTEMBER. THE ENSEMBLES ARE BETTER TODAY THAN YESTERDAY, WHICH SHOWED VERY LOW CONFIDENCE OVER THE WESTERN U.S. PUTTING THE TROUGH MORE IN DOUBT. TODAYS ENSEMBLES INDICATE MORE TROUGHING AND HIGHER CONFIDENCE THAN YESTERDAY'S RUNS. BASED ON GUIDANCE FROM HPC, WHICH USED A ECMWF/NCEP ENSEMBLE MEAN BLEND, A FAIRLY STRONG COLD FRONT WILL CROSS THE CWA FROM WEST TO EAST DURING TUESDAY. THIS FRONT MAY ACTUALLY WIND UP WHIPPING RIGHT THROUGH THE REGION AS UPSTAIRS A FAIRLY AMPLIFIED UPPER-LEVEL TROUGH MOVES INTO THE NORTHEAST (MIDLEVEL WINDS AROUND 50 KNOTS). WHILE THE MAIN SURFACE LOW IS FORECAST TO PASS WELL TO OUR NORTH INTO SOUTHEASTERN CANADA, SOME GOOD LOW-LEVEL CONVERGENCE AND PVA ARE FORECAST TO ARRIVE WITH THE FRONT. ALSO, A SURGE OF THETA-E IS EVIDENT PRIOR TO THE FRONT. THIS FRONT MAY ACTUALLY JUST PRODUCE A FAIRLY NARROW LINE OF SHOWERS (CONVECTION?) WITH LITTLE PRECIPITATION OCCURRING WELL AHEAD OF IT. A POSSIBLE FLY IN THE OINTMENT THOUGH COULD BE IF THE CANADIAN SOLUTION IS CORRECT AS IT DEVELOPS A SURFACE WAVE TO OUR SOUTH AND THE MOISTURE THEN RIDES NORTHWARD ALONG THE FRONT TUESDAY. THE GFS IS MORE PROGRESSIVE WITH ONLY THE HINT OF A WEAK SURFACE LOW DEVELOPING LATE TUESDAY IN NORTH CAROLINA. FOR NOW, WE BROUGHT IN LOW CHC POPS MONDAY EVENING ACROSS THE SOUTHERN POCONOS AS WAA MAY TRIGGER SOME SHOWERS. WE THEN INCREASED POPS FROM WEST TO EAST MONDAY NIGHT INTO TUESDAY, WITH HIGH CHC POPS FOR TUESDAY AS THE FRONT CROSSES THE REGION. BUFKIT FORECAST SOUNDINGS DO NOT REALLY INDICATE MUCH IF ANY SURFACE BASED CAPE, HOWEVER SOME ELEVATED CAPE COULD BE POSSIBLE. IF THE SHOWERS DO ARRIVE EARLY ENOUGH, THAT WILL LIMIT THE SURFACE HEATING AND REDUCE ANY THUNDER CHCS. FOR NOW, WE INCLUDED SOME THUNDER FROM ABOUT PHILADELPHIA ON SOUTHWARD. BASED ON UNCERTAINTY IN THE EXACT TIMING OF THE FRONT CLEARING THE REGION, WE HELD ONTO LOW CHC POPS FOR THE FIRST HALF OF TUESDAY NIGHT. MOST AREAS SHOULD BE DRY ON WEDNESDAY, HOWEVER WITH MUCH COOLER AIR ADVECTING IN ALOFT COUPLED WITH CYCLONIC FLOW, THERE COULD BE A SHOWER OR TWO ACROSS THE NORTHWEST ZONES. FOR THIS REASON, WE PLACED A SLIGHT CHC POP IN THE GRIDS FOR WEDNESDAY AFTERNOON AND EARLY EVENING. IT MAY BE BREEZY AT TIMES WEDNESDAY AS CAA OCCURS (850 MB TEMPERATURES DROP TO AROUND +2C WEDNESDAY AFTERNOON) UNDER A NORTHWESTERLY FLOW. THURSDAY AND FRIDAY SHOULD BE DRY AS A SURFACE HIGH SITUATES ITSELF OVER THE MID ATLANTIC, HOWEVER A DEVELOPING WARM FRONT IN THE OHIO VALLEY WILL EVENTUALLY GET SOME WAA GOING ALOFT. THE GFS SHOWS SOME MOISTURE STREAMING OUR WAY FRIDAY AFTERNOON. WHILE THIS MAY BE OVERDONE, PLENTY OF TIME TO WATCH MODEL TRENDS, THEREFORE ONLY WENT WITH A SLIGHT CHC IN THE GRIDS FRIDAY AFTERNOON FOR THE NORTHWEST ZONES. && .AVIATION... VFR CONDITIONS WHICH DOMINATED THE AREA THIS MORNING ARE SLOWLY IMPROVING AS THE PRIMARY AREA OF HEAVY RAIN AND A FEW EMBEDDED THUNDERSTORMS MOVE NORTHEAST AWAY FROM THE NEW JERSEY COAST THIS AFTERNOON. EXPECT MVFR CONDITIONS FOR THE REMAINDER OF THE DAYLIGHT HOURS WITH LOWERING CEILINGS AFTER SUNSET. SOME VSBY RESTRICTIONS ARE ALSO EXPECTED DURING THE OVERNIGHT HOURS WITH SCATTERED RAIN SHOWERS AND FOG. CLOUDS ARE EXPECTED TO PERSIST INTO THE EARLY AFTERNOON HOURS ON SATURDAY, BUT THEN CONDITIONS WILL IMPROVE ONCE THE UPPER LEVEL LOW MOVES SOUTHEAST AWAY FROM THE MID ATLANTIC COAST. && .MARINE... SCA HEADLINES REMAIN WHERE THEY WERE. SEAS ARE IN THE 4 FOOT RANGE THIS FRI AFTERNOON, SANDWICHED BETWEEN 5 FOOT + NORTH AND SOUTH OF PHI'S FORECAST TERRITORY, THANKS TO OUR LOCATION RELATIVE TO THE SURFACE AND UPPER LEVEL LOW PRESSURE SYSTEMS. AS THE FETCH INCREASES DURING THE NEXT 12 TO 24 HOURS, SO WILL THE SEAS TO THE 5 TO 6 FOOT RANGE THROUGH SATURDAY. AS THE UPPER LEVEL LOW MOVES AWAY, SEAS WILL SUBSIDE LATE SATURDAY AND SUNDAY. && .HYDROLOGY... OCEAN COUNTY, NEW JERSEY GOT PUMMELED TODAY WITH TORRENTIAL RAINFALL. KDIX-88D STORM TOTAL ESTIMATES OF 6 TO 8 INCHES IN CENTRAL AND SOUTHERN OCEAN COUNTY. THE RADAR WAS GREATLY UNDERESTIMATING THE RAINFALL, AND A COMPARISON WITH THE SIDE-BY-SIDE RUNNING OF THE TROPICAL Z/R POINTED IN THE RIGHT DIRECTION. THEREFORE, WE CHANGED THE Z/R RELATIONSHIP INTO THE CONVECTION MODE EARLY THIS MORNING. THIS IMPROVED THE RAINFALL ESTIMATES. WE RECEIVED SOME GROUND TRUTH WITH 8.82 INCHES OF RAIN IN BAYVILLE AND 8.00 INCHES ON LONG BEACH ISLAND. THIS TORRENTIAL RAINFALL LEAD TO MAJOR FLASH FLOODING IN PARTS OF OCEAN COUNTY. THE EXCESSIVE RAIN THAT WE SAW TODAY SHOULD NOT OCCUR TONIGHT INTO SATURDAY AS THE UPPER-LEVEL LOW SLOWLY SETTLES SOUTHEASTWARD AND THE ASSOCIATED SURFACE LOW MOVES FARTHER AWAY. HOWEVER ANOTHER INCH OF RAIN IS QUITE POSSIBLE IN SOME NORTHERN AREAS AS REMAINING PRECIPITATION PIVOTS AROUND THE SOUTHEASTWARD DRIFTING UPPER-LEVEL LOW. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY FOR ANZ450>455 FROM MIDNIGHT SATURDAY UNTIL 1 AM SUNDAY. && $$ SYNOPSIS/NEAR TERM/SHORT TERM...GORSE LONG TERM...GORSE/HPC AVIATION/MARINE...MIKETTA HYDROLOGY...GORSE pa