Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 10/27/08

AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1115 AM EDT SAT OCT 25 2008 .UPDATE... WILL UPDATE TO A MORE OPTIMISTIC SIDE. UPPER TROF CURRENTLY LIFTING THROUGH LOWER MICHIGAN WITH DRY SLOT WRAPPING INTO SOUTHEAST MICHIGAN. DRY AIR MIXING WITH LOW LEVEL MOISTURE AND CLOUDS IS BRINGING A FAIRLY DECENT DECREASE IN CLOUD COVER. ALSO SUBSIDENCE BEHIND THE TROF WILL HELP WITH THE MIXING AND EROSION OF CLOUD COVER. VISIBLE SATELLITE SHOWS MORE SOLID DECK OF LOW CLOUDS ACROSS WESTERN MICHIGAN SLOWLY ERODING AS IT WORKS NORTHEAST. THIS WILL BRING GENERALLY PARTLY CLOUDY SKIES THIS AFTERNOON. HAVE ALSO PULLED BACK CHANCE OF SHOWERS TO MAINLY THE SAGINAW VALLEY AND THUMB AND LOWERED POPS AS THE DEEPER MOISTURE AND COLD POOL LIFTS JUST NORTH OF THIS AREA. WIND GUSTS WILL CONTINUE TO PICK UP DURING THE AFTERNOON AS MIXING WILL REACH UP TO THE 700MB LEVEL WHERE WINDS ARE GENERALLY AROUND 30KTS. THAT SHOULD LEAD TO SOME WIND GUSTS UP TO 30 MPH AT THE SURFACE. WILL LEAVE HIGHS ALONE AS GENERALLY LOW 50S NORTH TO MID 50S SOUTH LOOK ON TRACK. && .AVIATION... THE MORE SUBSTANTIAL PART OF THE FORECAST FOR TODAY AND TONIGHT WILL BE THE INCREASING SOUTHWEST WINDS THAT WILL HAVE GUSTS TO 25 KNOTS BY LATE MORNING BEFORE SETTLING INTO A STEADY 15 KNOT SUSTAINED TONIGHT. EXPECT VFR CONDITIONS TO PERSIST TODAY AND TONIGHT UNTIL PERHAPS CLOSER TO SUNRISE WHEN THE NEXT ROUND OF SHOWERS WILL MOVE INTO THE REGION. RAIN THIS MORNING WILL BECOME LESS OF A PROBLEM BUT MVFR CEILING WILL PERSIST FOR A FEW MORE HOURS. THERE WILL BE SOME BRIEF VARIABILITY BETWEEN IFR AND VFR ON THE CEILING CONDITIONS BUT VISIBILITY WILL BE CONSISTENTLY VFR. THE CLOUDS WILL GRADUALLY LIFT INTO A VFR CEILING DURING THE AFTERNOON OVER ALL OF SE MICHIGAN. WHAT SHOWERS ARE REMAINING BY THEN WILL BE CONFINED TO THE TRI CITIES AREA BUT WITH COVERAGE TOO LOW TO INCLUDE IN THE TERMINAL FORECASTS. && .PREV DISCUSSION...ISSUED 406 AM EDT SAT OCT 25 2008 SHORT TERM...TODAY LOW PRESSURE AND SCATTERED SHOWERS WILL PIVOT THE REST OF THE WAY THROUGH THE GREAT LAKES TODAY. SHOWERS ARE LIKELY EVERYWHERE BEFORE SUNRISE AND THEN THE BEST CHANCE OF RAIN WILL OCCUR IN THE SAGINAW VALLEY AND THUMB DURING THE REST OF THE DAY. OUTSIDE OF RAIN AREAS, CLOUDS WILL PREVENT ANYTHING MORE THAN A MODEST RISE IN TEMPERATURES. COMPOSITE RADAR IMAGERY SHOWS A DISTINCT SWIRL OF SHOWERS MOVING THROUGH LOWER MICHIGAN ASSOCIATED WITH THE LOW PRESSURE SYSTEM CENTERED OVER SOUTHERN LAKE MICHIGAN. COLD MID AND UPPER LEVEL TEMPERATURES HAVE ALSO RESULTED IN SOME DEEPER CONVECTION UNDER THE CORE OF THE UPPER LOW BUT ADDITIONAL LIGHTNING STRIKES HAVE BEEN ABSENT OVER THE LAST FEW HOURS. PLAN TO HOLD OFF FOR NOW ON ADDING THUNDER TO THE FORECAST AS THE COLD CORE PASSES JUST TO OUR WEST AND NORTH DURING THE AFTERNOON. DAYTIME HEATING WILL STEEPEN THE LAPSE RATES IN THE TRI CITIES AREA THIS AFTERNOON UNDER 500 MB TEMPS THAT ARE NEARLY 2 STANDARD DEVIATIONS BELOW NORMAL AT -24C. FARTHER SOUTH, DRY AIR WILL MOVE IN THROUGH THE MID LEVELS BY AFTERNOON AND CUT OFF THE SHOWER CHANCES TOWARD THE DETROIT AREA. LOWER CLOUDS WILL BE PLENTIFUL, HOWEVER, AND THIS WILL LIMIT THE AFTERNOON TEMPERATURE REBOUND, BUT MID TO UPPER 50S SHOULD BE REACHABLE WITH THE HELP OF INCREASING SOUTHWEST WINDS. LONG TERM...TONIGHT THROUGH NEXT FRIDAY THE HARBINGER OF ACTIVE WEATHER...A MAMMOTH POLAR JET CORE OF +160 KNOTS...IS NOW WELL ONSHORE EDGING INTO FAR SOUTHERN ALBERTA IN VICINITY OF THE MONTANA BORDER. LATEST OBSERVATIONS...SOUNDING AIRCRAFT SATELLITE...CONFIRM UPPER TROPOSPHERIC WINDS (140 TO 160 KNOTS) TO BE QUITE WIDESPREAD ACROSS PORTIONS OF BRITISH COLUMBIA AND ALBERTA. IN ADVANCE OF THE JET STREAK AND SUBSEQUENT LONGWAVE TROUGH AMPLIFICATION...EXPECTING A BRIEF PERIOD OF HEIGHT RISES THE FIRST HALF OF TONIGHT. PLENTY OF MIDLEVEL DRY AIR IS PROGGED FOR THE SOUTHERN HALF OF THE CWA IN THE LATEST NAM/GFS. HOWEVER...THIS ALL CHANGES THE LATTER HALF OF THE NIGHT AS THE NOSE OF THE U/L JET PUSHES INTO FAR WESTERN LOWER MICHIGAN AND VERY STRONG CVA COMMENCES. CURRENT WATER VAPOR IMAGERY INDICATES A SHARPER SHORTWAVE RIDGE (THAN SUGGESTED BY MODELS) AND STRONGER SUBSIDENCE/DRYING ACROSS THE DAKOTAS. HEIGHT FALLS IN ADVANCE OF THE JET STREAK TODAY AND THE PROPENSITY FOR PHASING OF THE NEW AND OLD SYSTEMS WILL REALLY WORK AGAINST LONG LASTING EFFECTS OF THE INCREASED HEIGHTS. WITH THIS THINKING...HAVE MENTIONED A DRY FORECAST FOR THE SOUTH AND A SLIGHT CHANCE FOR RAIN SHOWERS NORTH PRIOR TO 6Z. THERE WILL BE INCREASED POPS CWA-WIDE FOR THE 6-12Z TIMEFRAME. WITH CVA/LEFT EXIT REGION DYNAMICS AND DEPICTIONS OF HIGHER COLUMN RH HAVE INCLUDED LIKELY POPS FOR THE TRI CITIES AND MUCH OF THE THUMB. AN AIRMASS CHANGE...WILL BE HERALDED BY A COLD/OCCLUDED FRONT...FORECASTED TO PASS THROUGH SOUTHEASTERN MICHIGAN SUNDAY MORNING. THE PARENT LOW PRESSURE CENTER WILL BE LOCATED ACROSS PORTIONS OF CENTRAL ONTARIO WITH A DEEP MIDLEVEL/SURFACE TROUGH CENTERED THROUGH THE GREAT LAKES. THE LATEST DEVELOPMENT OF THE GFS AND EVEN THE NAM IN SOME REGARD IS TO CHANGE GEARS WITH LOCALIZED CYCLOGENESIS IMMEDIATELY NORTHEAST OF GEORGIAN BAY DUE TO A LAKE AGGREGATE RESPONSE. THE WELL ESTABLISHED CYCLONIC FLOW WITHIN THE TROUGH COMPLEX AND WARM WATERS OF THE GREAT LAKES SUGGEST THIS IS A SOLUTION THAT BEARS CONSIDERABLE WATCHING. THE NAM DID SHOW A STRONGER SURFACE TROUGH INCREASING THE GRADIENT OVER MICHIGAN BUT FAILED TO CLOSE ANY SURFACE ISOBARS. THE IMPORTANCE OF THIS IS ULTIMATELY HOW STRONG SURFACE WINDS WILL GET ON SUNDAY. WITH NO LOCALIZED LOW IN THE UKMET/CANADIAN WILL CONTINUE THE PREVIOUS THINKING OF SUSTAINED WINDS BETWEEN 25 AND 30 MPH WITH WIND GUSTS OF UP TO 45 MPH. TURBULENT MIXING IN ADVANCE OF THIS FIRST SURFACE TROUGH SHOULD ALLOW FOR COMPRESSIONAL WARMING...HIGHS IN THE LOWER TO MID 50S. WILL CARRY CHANCE POPS IN THE FORECAST SUNDAY THROUGH MONDAY NIGHT...PER OVERLAKE INSTABILITY AND DEEP CYCLONIC FLOW. ATTM...NO WIDESPREAD PRECIPITATION IS ANTICIPATED WITH THE GENERAL LACK OF DEEP MOISTURE AND NORTHWEST FLOW TRAJECTORIES. THE HIGHER CHANCE POPS ARE FOR SUNDAY NIGHT PER 1000-500MB RH PLAN VIEW FRAMES AND LOCALIZED I 94 CONVERGENCE BAND OFF OF LAKE MICHIGAN. THERMAL PROFILES CONTINUE TO SUPPORT A RAIN/SNOW MIX. HIGHS WILL STRUGGLE TO HIT 40 MONDAY AND TUESDAY...WHICH IS 15 TO 20 DEGREES BELOW NORMAL. MARINE... GALE WARNINGS HAVE BEEN ISSUE FOR ALL MARINE AREAS AS THE STRONG COLD FRONT REMAINS ON SCHEDULE FOR SUNDAY. SMALL CRAFT ADVISORIES ARE IN EFFECT THIS AFTERNOON AND TONIGHT AS SOUTHWEST WINDS INCREASE AHEAD OF THE FRONT. HOWEVER, THE BIGGER WEATHER STORY IS THE STRONG COLD FRONT THAT WILL PLOW THROUGH THE CENTRAL GREAT LAKES EARLY SUNDAY...LEADING TO GALE FORCE WESTERLY WINDS OVER ALL MARINE AREAS SUNDAY INTO MONDAY...AS VERY COLD AIR FILTERS INTO THE REGION. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON... SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON INCLUDING SAGINAW BAY...FROM NOON SATURDAY TO 4 AM SUNDAY. GALE WARNING...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON INCLUDING SAGINAW BAY...FROM 4 AM SUNDAY TO 11 AM MONDAY. GALE WARNING...LHZ361-LHZ362-LHZ363-LHZ462-LHZ463-LHZ464...FROM 4 AM SUNDAY TO 5 PM MONDAY. LAKE ST CLAIR... GALE WARNING...FROM 4 AM SUNDAY TO 11 AM MONDAY. SMALL CRAFT ADVISORY...FROM NOON SATURDAY TO 4 AM SUNDAY. MI WATERS OF LAKE ERIE... GALE WARNING...FROM 4 AM SUNDAY TO 11 AM MONDAY. SMALL CRAFT ADVISORY...FROM NOON SATURDAY TO 4 AM SUNDAY. && $$ UPDATE.......DRC AVIATION.....BT SHORT TERM...BT LONG TERM....CB MARINE.......BT YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
711 AM EDT SAT OCT 25 2008 .AVIATION... THE MORE SUBSTANTIAL PART OF THE FORECAST FOR TODAY AND TONIGHT WILL BE THE INCREASING SOUTHWEST WINDS THAT WILL HAVE GUSTS TO 25 KNOTS BY LATE MORNING BEFORE SETTLING INTO A STEADY 15 KNOT SUSTAINED TONIGHT. EXPECT VFR CONDITIONS TO PERSIST TODAY AND TONIGHT UNTIL PERHAPS CLOSER TO SUNRISE WHEN THE NEXT ROUND OF SHOWERS WILL MOVE INTO THE REGION. RAIN THIS MORNING WILL BECOME LESS OF A PROBLEM BUT MVFR CEILING WILL PERSIST FOR A FEW MORE HOURS. THERE WILL BE SOME BRIEF VARIABILITY BETWEEN IFR AND VFR ON THE CEILING CONDITIONS BUT VISIBILITY WILL BE CONSISTENTLY VFR. THE CLOUDS WILL GRADUALLY LIFT INTO A VFR CEILING DURING THE AFTERNOON OVER ALL OF SE MICHIGAN. WHAT SHOWERS ARE REMAINING BY THEN WILL BE CONFINED TO THE TRI CITIES AREA BUT WITH COVERAGE TOO LOW TO INCLUDE IN THE TERMINAL FORECASTS. && .PREV DISCUSSION...ISSUED 406 AM EDT SAT OCT 25 2008 SHORT TERM...TODAY LOW PRESSURE AND SCATTERED SHOWERS WILL PIVOT THE REST OF THE WAY THROUGH THE GREAT LAKES TODAY. SHOWERS ARE LIKELY EVERYWHERE BEFORE SUNRISE AND THEN THE BEST CHANCE OF RAIN WILL OCCUR IN THE SAGINAW VALLEY AND THUMB DURING THE REST OF THE DAY. OUTSIDE OF RAIN AREAS, CLOUDS WILL PREVENT ANYTHING MORE THAN A MODEST RISE IN TEMPERATURES. COMPOSITE RADAR IMAGERY SHOWS A DISTINCT SWIRL OF SHOWERS MOVING THROUGH LOWER MICHIGAN ASSOCIATED WITH THE LOW PRESSURE SYSTEM CENTERED OVER SOUTHERN LAKE MICHIGAN. COLD MID AND UPPER LEVEL TEMPERATURES HAVE ALSO RESULTED IN SOME DEEPER CONVECTION UNDER THE CORE OF THE UPPER LOW BUT ADDITIONAL LIGHTNING STRIKES HAVE BEEN ABSENT OVER THE LAST FEW HOURS. PLAN TO HOLD OFF FOR NOW ON ADDING THUNDER TO THE FORECAST AS THE COLD CORE PASSES JUST TO OUR WEST AND NORTH DURING THE AFTERNOON. DAYTIME HEATING WILL STEEPEN THE LAPSE RATES IN THE TRI CITIES AREA THIS AFTERNOON UNDER 500 MB TEMPS THAT ARE NEARLY 2 STANDARD DEVIATIONS BELOW NORMAL AT -24C. FARTHER SOUTH, DRY AIR WILL MOVE IN THROUGH THE MID LEVELS BY AFTERNOON AND CUT OFF THE SHOWER CHANCES TOWARD THE DETROIT AREA. LOWER CLOUDS WILL BE PLENTIFUL, HOWEVER, AND THIS WILL LIMIT THE AFTERNOON TEMPERATURE REBOUND, BUT MID TO UPPER 50S SHOULD BE REACHABLE WITH THE HELP OF INCREASING SOUTHWEST WINDS. LONG TERM...TONIGHT THROUGH NEXT FRIDAY THE HARBINGER OF ACTIVE WEATHER...A MAMMOTH POLAR JET CORE OF +160 KNOTS...IS NOW WELL ONSHORE EDGING INTO FAR SOUTHERN ALBERTA IN VICINITY OF THE MONTANA BORDER. LATEST OBSERVATIONS...SOUNDING AIRCRAFT SATELLITE...CONFIRM UPPER TROPOSPHERIC WINDS (140 TO 160 KNOTS) TO BE QUITE WIDESPREAD ACROSS PORTIONS OF BRITISH COLUMBIA AND ALBERTA. IN ADVANCE OF THE JET STREAK AND SUBSEQUENT LONGWAVE TROUGH AMPLIFICATION...EXPECTING A BRIEF PERIOD OF HEIGHT RISES THE FIRST HALF OF TONIGHT. PLENTY OF MIDLEVEL DRY AIR IS PROGGED FOR THE SOUTHERN HALF OF THE CWA IN THE LATEST NAM/GFS. HOWEVER...THIS ALL CHANGES THE LATTER HALF OF THE NIGHT AS THE NOSE OF THE U/L JET PUSHES INTO FAR WESTERN LOWER MICHIGAN AND VERY STRONG CVA COMMENCES. CURRENT WATER VAPOR IMAGERY INDICATES A SHARPER SHORTWAVE RIDGE (THAN SUGGESTED BY MODELS) AND STRONGER SUBSIDENCE/DRYING ACROSS THE DAKOTAS. HEIGHT FALLS IN ADVANCE OF THE JET STREAK TODAY AND THE PROPENSITY FOR PHASING OF THE NEW AND OLD SYSTEMS WILL REALLY WORK AGAINST LONG LASTING EFFECTS OF THE INCREASED HEIGHTS. WITH THIS THINKING...HAVE MENTIONED A DRY FORECAST FOR THE SOUTH AND A SLIGHT CHANCE FOR RAIN SHOWERS NORTH PRIOR TO 6Z. THERE WILL BE INCREASED POPS CWA-WIDE FOR THE 6-12Z TIMEFRAME. WITH CVA/LEFT EXIT REGION DYNAMICS AND DEPICTIONS OF HIGHER COLUMN RH HAVE INCLUDED LIKELY POPS FOR THE TRI CITIES AND MUCH OF THE THUMB. AN AIRMASS CHANGE...WILL BE HERALDED BY A COLD/OCCLUDED FRONT...FORECASTED TO PASS THROUGH SOUTHEASTERN MICHIGAN SUNDAY MORNING. THE PARENT LOW PRESSURE CENTER WILL BE LOCATED ACROSS PORTIONS OF CENTRAL ONTARIO WITH A DEEP MIDLEVEL/SURFACE TROUGH CENTERED THROUGH THE GREAT LAKES. THE LATEST DEVELOPMENT OF THE GFS AND EVEN THE NAM IN SOME REGARD IS TO CHANGE GEARS WITH LOCALIZED CYCLOGENESIS IMMEDIATELY NORTHEAST OF GEORGIAN BAY DUE TO A LAKE AGGREGATE RESPONSE. THE WELL ESTABLISHED CYCLONIC FLOW WITHIN THE TROUGH COMPLEX AND WARM WATERS OF THE GREAT LAKES SUGGEST THIS IS A SOLUTION THAT BEARS CONSIDERABLE WATCHING. THE NAM DID SHOW A STRONGER SURFACE TROUGH INCREASING THE GRADIENT OVER MICHIGAN BUT FAILED TO CLOSE ANY SURFACE ISOBARS. THE IMPORTANCE OF THIS IS ULTIMATELY HOW STRONG SURFACE WINDS WILL GET ON SUNDAY. WITH NO LOCALIZED LOW IN THE UKMET/CANADIAN WILL CONTINUE THE PREVIOUS THINKING OF SUSTAINED WINDS BETWEEN 25 AND 30 MPH WITH WIND GUSTS OF UP TO 45 MPH. TURBULENT MIXING IN ADVANCE OF THIS FIRST SURFACE TROUGH SHOULD ALLOW FOR COMPRESSIONAL WARMING...HIGHS IN THE LOWER TO MID 50S. WILL CARRY CHANCE POPS IN THE FORECAST SUNDAY THROUGH MONDAY NIGHT...PER OVERLAKE INSTABILITY AND DEEP CYCLONIC FLOW. ATTM...NO WIDESPREAD PRECIPITATION IS ANTICIPATED WITH THE GENERAL LACK OF DEEP MOISTURE AND NORTHWEST FLOW TRAJECTORIES. THE HIGHER CHANCE POPS ARE FOR SUNDAY NIGHT PER 1000-500MB RH PLAN VIEW FRAMES AND LOCALIZED I 94 CONVERGENCE BAND OFF OF LAKE MICHIGAN. THERMAL PROFILES CONTINUE TO SUPPORT A RAIN/SNOW MIX. HIGHS WILL STRUGGLE TO HIT 40 MONDAY AND TUESDAY...WHICH IS 15 TO 20 DEGREES BELOW NORMAL. MARINE... GALE WARNINGS HAVE BEEN ISSUE FOR ALL MARINE AREAS AS THE STRONG COLD FRONT REMAINS ON SCHEDULE FOR SUNDAY. SMALL CRAFT ADVISORIES ARE IN EFFECT THIS AFTERNOON AND TONIGHT AS SOUTHWEST WINDS INCREASE AHEAD OF THE FRONT. HOWEVER, THE BIGGER WEATHER STORY IS THE STRONG COLD FRONT THAT WILL PLOW THROUGH THE CENTRAL GREAT LAKES EARLY SUNDAY...LEADING TO GALE FORCE WESTERLY WINDS OVER ALL MARINE AREAS SUNDAY INTO MONDAY...AS VERY COLD AIR FILTERS INTO THE REGION. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON... SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON INCLUDING SAGINAW BAY...FROM NOON SATURDAY TO 4 AM SUNDAY. GALE WARNING...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON INCLUDING SAGINAW BAY...FROM 4 AM SUNDAY TO 11 AM MONDAY. GALE WARNING...LHZ361-LHZ362-LHZ363-LHZ462-LHZ463-LHZ464...FROM 4 AM SUNDAY TO 5 PM MONDAY. LAKE ST CLAIR... GALE WARNING...FROM 4 AM SUNDAY TO 11 AM MONDAY. SMALL CRAFT ADVISORY...FROM NOON SATURDAY TO 4 AM SUNDAY. MI WATERS OF LAKE ERIE... GALE WARNING...FROM 4 AM SUNDAY TO 11 AM MONDAY. SMALL CRAFT ADVISORY...FROM NOON SATURDAY TO 4 AM SUNDAY. && $$ AVIATION.....BT SHORT TERM...BT LONG TERM....CB MARINE.......BT YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
406 AM EDT SAT OCT 25 2008 .SHORT TERM...TODAY LOW PRESSURE AND SCATTERED SHOWERS WILL PIVOT THE REST OF THE WAY THROUGH THE GREAT LAKES TODAY. SHOWERS ARE LIKELY EVERYWHERE BEFORE SUNRISE AND THEN THE BEST CHANCE OF RAIN WILL OCCUR IN THE SAGINAW VALLEY AND THUMB DURING THE REST OF THE DAY. OUTSIDE OF RAIN AREAS, CLOUDS WILL PREVENT ANYTHING MORE THAN A MODEST RISE IN TEMPERATURES. COMPOSITE RADAR IMAGERY SHOWS A DISTINCT SWIRL OF SHOWERS MOVING THROUGH LOWER MICHIGAN ASSOCIATED WITH THE LOW PRESSURE SYSTEM CENTERED OVER SOUTHERN LAKE MICHIGAN. COLD MID AND UPPER LEVEL TEMPERATURES HAVE ALSO RESULTED IN SOME DEEPER CONVECTION UNDER THE CORE OF THE UPPER LOW BUT ADDITIONAL LIGHTNING STRIKES HAVE BEEN ABSENT OVER THE LAST FEW HOURS. PLAN TO HOLD OFF FOR NOW ON ADDING THUNDER TO THE FORECAST AS THE COLD CORE PASSES JUST TO OUR WEST AND NORTH DURING THE AFTERNOON. DAYTIME HEATING WILL STEEPEN THE LAPSE RATES IN THE TRI CITIES AREA THIS AFTERNOON UNDER 500 MB TEMPS THAT ARE NEARLY 2 STANDARD DEVIATIONS BELOW NORMAL AT -24C. FARTHER SOUTH, DRY AIR WILL MOVE IN THROUGH THE MID LEVELS BY AFTERNOON AND CUT OFF THE SHOWER CHANCES TOWARD THE DETROIT AREA. LOWER CLOUDS WILL BE PLENTIFUL, HOWEVER, AND THIS WILL LIMIT THE AFTERNOON TEMPERATURE REBOUND, BUT MID TO UPPER 50S SHOULD BE REACHABLE WITH THE HELP OF INCREASING SOUTHWEST WINDS. && .LONG TERM...TONIGHT THROUGH NEXT FRIDAY THE HARBINGER OF ACTIVE WEATHER...A MAMMOTH POLAR JET CORE OF +160 KNOTS...IS NOW WELL ONSHORE EDGING INTO FAR SOUTHERN ALBERTA IN VICINITY OF THE MONTANA BORDER. LATEST OBSERVATIONS...SOUNDING AIRCRAFT SATELLITE...CONFIRM UPPER TROPOSPHERIC WINDS (140 TO 160 KNOTS) TO BE QUITE WIDESPREAD ACROSS PORTIONS OF BRITISH COLUMBIA AND ALBERTA. IN ADVANCE OF THE JET STREAK AND SUBSEQUENT LONGWAVE TROUGH AMPLIFICATION...EXPECTING A BRIEF PERIOD OF HEIGHT RISES THE FIRST HALF OF TONIGHT. PLENTY OF MIDLEVEL DRY AIR IS PROGGED FOR THE SOUTHERN HALF OF THE CWA IN THE LATEST NAM/GFS. HOWEVER...THIS ALL CHANGES THE LATTER HALF OF THE NIGHT AS THE NOSE OF THE U/L JET PUSHES INTO FAR WESTERN LOWER MICHIGAN AND VERY STRONG CVA COMMENCES. CURRENT WATER VAPOR IMAGERY INDICATES A SHARPER SHORTWAVE RIDGE (THAN SUGGESTED BY MODELS) AND STRONGER SUBSIDENCE/DRYING ACROSS THE DAKOTAS. HEIGHT FALLS IN ADVANCE OF THE JET STREAK TODAY AND THE PROPENSITY FOR PHASING OF THE NEW AND OLD SYSTEMS WILL REALLY WORK AGAINST LONG LASTING EFFECTS OF THE INCREASED HEIGHTS. WITH THIS THINKING...HAVE MENTIONED A DRY FORECAST FOR THE SOUTH AND A SLIGHT CHANCE FOR RAIN SHOWERS NORTH PRIOR TO 6Z. THERE WILL BE INCREASED POPS CWA-WIDE FOR THE 6-12Z TIMEFRAME. WITH CVA/LEFT EXIT REGION DYNAMICS AND DEPICTIONS OF HIGHER COLUMN RH HAVE INCLUDED LIKELY POPS FOR THE TRI CITIES AND MUCH OF THE THUMB. AN AIRMASS CHANGE...WILL BE HERALDED BY A COLD/OCCLUDED FRONT...FORECASTED TO PASS THROUGH SOUTHEASTERN MICHIGAN SUNDAY MORNING. THE PARENT LOW PRESSURE CENTER WILL BE LOCATED ACROSS PORTIONS OF CENTRAL ONTARIO WITH A DEEP MIDLEVEL/SURFACE TROUGH CENTERED THROUGH THE GREAT LAKES. THE LATEST DEVELOPMENT OF THE GFS AND EVEN THE NAM IN SOME REGARD IS TO CHANGE GEARS WITH LOCALIZED CYCLOGENESIS IMMEDIATELY NORTHEAST OF GEORGIAN BAY DUE TO A LAKE AGGREGATE RESPONSE. THE WELL ESTABLISHED CYCLONIC FLOW WITHIN THE TROUGH COMPLEX AND WARM WATERS OF THE GREAT LAKES SUGGEST THIS IS A SOLUTION THAT BEARS CONSIDERABLE WATCHING. THE NAM DID SHOW A STRONGER SURFACE TROUGH INCREASING THE GRADIENT OVER MICHIGAN BUT FAILED TO CLOSE ANY SURFACE ISOBARS. THE IMPORTANCE OF THIS IS ULTIMATELY HOW STRONG SURFACE WINDS WILL GET ON SUNDAY. WITH NO LOCALIZED LOW IN THE UKMET/CANADIAN WILL CONTINUE THE PREVIOUS THINKING OF SUSTAINED WINDS BETWEEN 25 AND 30 MPH WITH WIND GUSTS OF UP TO 45 MPH. TURBULENT MIXING IN ADVANCE OF THIS FIRST SURFACE TROUGH SHOULD ALLOW FOR COMPRESSIONAL WARMING...HIGHS IN THE LOWER TO MID 50S. WILL CARRY CHANCE POPS IN THE FORECAST SUNDAY THROUGH MONDAY NIGHT...PER OVERLAKE INSTABILITY AND DEEP CYCLONIC FLOW. ATTM...NO WIDESPREAD PRECIPITATION IS ANTICIPATED WITH THE GENERAL LACK OF DEEP MOISTURE AND NORTHWEST FLOW TRAJECTORIES. THE HIGHER CHANCE POPS ARE FOR SUNDAY NIGHT PER 1000-500MB RH PLAN VIEW FRAMES AND LOCALIZED I 94 CONVERGENCE BAND OFF OF LAKE MICHIGAN. THERMAL PROFILES CONTINUE TO SUPPORT A RAIN/SNOW MIX. HIGHS WILL STRUGGLE TO HIT 40 MONDAY AND TUESDAY...WHICH IS 15 TO 20 DEGREES BELOW NORMAL. && .MARINE... GALE WARNINGS HAVE BEEN ISSUE FOR ALL MARINE AREAS AS THE STRONG COLD FRONT REMAINS ON SCHEDULE FOR SUNDAY. SMALL CRAFT ADVISORIES ARE IN EFFECT THIS AFTERNOON AND TONIGHT AS SOUTHWEST WINDS INCREASE AHEAD OF THE FRONT. HOWEVER, THE BIGGER WEATHER STORY IS THE STRONG COLD FRONT THAT WILL PLOW THROUGH THE CENTRAL GREAT LAKES EARLY SUNDAY...LEADING TO GALE FORCE WESTERLY WINDS OVER ALL MARINE AREAS SUNDAY INTO MONDAY...AS VERY COLD AIR FILTERS INTO THE REGION. && .PREV DISCUSSION...ISSUED 108 AM EDT SAT OCT 25 2008 AVIATION... EXPECT GENERALLY MVFR CEILINGS EARLY THIS MORNING AS LOW LEVEL MOISTURE WITH INTERMITTENT SHOWERS STREAMS THROUGH THE AREA. WILL HAVE TO WATCH FOR PATCHES OF IFR STILL AS WELL. ATTM...IT APPEARS ANY ADDITIONAL SHOWER ACTIVITY WILL BE MINIMAL. CONDITIONS WILL IMPROVE IN TERMS OF CEILINGS LATER TODAY WITH LOWER VFR CEILINGS OF 3500-4500 FEET WHICH WILL BECOME SCT LATE IN THE DAY. WEST/SOUTHWEST WINDS WILL INCREASE THOUGH WITH GUSTS TO 25 KNOTS POSSIBLE BY LATE MORNING ON INTO THE AFTERNOON. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON... SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON INCLUDING SAGINAW BAY...FROM NOON SATURDAY TO 4 AM SUNDAY. GALE WARNING...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON INCLUDING SAGINAW BAY...FROM 4 AM SUNDAY TO 11 AM MONDAY. GALE WARNING...LHZ361-LHZ362-LHZ363-LHZ462-LHZ463-LHZ464...FROM 4 AM SUNDAY TO 5 PM MONDAY. LAKE ST CLAIR... GALE WARNING...FROM 4 AM SUNDAY TO 11 AM MONDAY. SMALL CRAFT ADVISORY...FROM NOON SATURDAY TO 4 AM SUNDAY. MI WATERS OF LAKE ERIE... GALE WARNING...FROM 4 AM SUNDAY TO 11 AM MONDAY. SMALL CRAFT ADVISORY...FROM NOON SATURDAY TO 4 AM SUNDAY. && $$ SHORT TERM...BT LONG TERM....CB MARINE.......BT AVIATION.....DG YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1055 AM EDT SAT OCT 25 2008 .SYNOPSIS... AN AREA OF LOW PRESSURE WILL TRACK NORTH ACROSS EASTERN NORTH CAROLINA TODAY. WARM AND DRIER AIR WILL QUICKLY BUILD INTO THE AREA FROM THE SOUTHWEST SATURDAY NIGHT AND INTO SUNDAY. A COLD FRONT WILL APPROACH FROM THE NORTHWEST BY MONDAY MORNING...BRINGING MUCH COLDER TEMPERATURES TO THE REGION THROUGH MID WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1055 AM SATURDAY... THE LATEST SURFACE ANALYSIS SHOWS THE TRIPLE POINT SURFACE LOW OVER THE SOUTHERN SANDHILLS... WITH AN INVERTED TROUGH EXTENDING NNW THROUGH THE NW PIEDMONT AND A STEADY SOUTHEASTERLY BOUNDARY LAYER FLOW OVER MUCH OF CENTRAL NC. STRONG LOW LEVEL ISENTROPIC UPGLIDE AND MOISTURE TRANSPORT PERSISTS TO THE NORTH AND EAST OF THIS LOW... WHICH IS SUPPORTING CONTINUED REDEVELOPMENT OF AREAS OF RAIN AND DRIZZLE OVER ALL BUT THE FAR SW CWA. MORNING AMDAR AIRCRAFT SOUNDINGS ALONG WITH AREA UPPER AIR DATA INDICATE DEEP SURFACE-BASED SATURATION IN A FAIRLY STABLE LAYER OVER 2 KM DEEP OVER CENTRAL NC. REMARKABLY DRY AIR IS NOTED ABOVE IT... WITH AN 850 MB DEWPOINT DEPRESSION OF 30C AND 43C AT ATLANTA AND BIRMINGHAM RESPECTIVELY... AND THE ATLANTA SOUNDING SHOWS A MUCH SHALLOWER MOIST LAYER. AS THE 850 MB TROUGH HAS PIVOTED EAST INTO THE FAR WESTERN PIEDMONT... VISIBLE SATELLITE IMAGERY SHOWS SOME DOWNSLOPE DRYING TAKING PLACE OVER THE FOOTHILLS. BUT THE LATEST RUC MODEL SUGGESTS THAT THE LEADING EDGE OF THE WSW FLOW AT 925-850 MB WILL BE SLOW TO SWEEP THROUGH CENTRAL NC THIS AFTERNOON. BASED ON THE VERTICAL EXTENT OF THE MOIST AIR... THE CAPPING ABOVE IT... THE DELAYED DOWNSLOPE DRYING... AND THE LACK OF ANY OTHER MECHANISM TO MIX OUT OR BURN OFF SUCH A DEEP LAYER... HAVE DELAYED CLEARING UNTIL LATE THIS AFTERNOON. THE LOW LEVEL MOISTURE TRANSPORT SHOULD BE SLOW TO SHIFT TO THE ENE AS WELL... THUS HAVE HELD ONTO A CHANCE OF RAIN OR DRIZZLE... TAPERING OFF SW TO NE DURING THE AFTERNOON. TEMPERATURES ARE QUITE TRICKY... ALREADY HAVING RISEN CLOSE TO THEIR FORECAST HIGHS OVER MUCH OF THE AREA... BUT WITH ONLY SMALL ADDITIONAL RISES THROUGH THE AFTERNOON. HAVE MADE ADJUSTMENTS TO HOURLY TEMP FORECASTS INTO THIS EVENING... WHICH SHAKES OUT TO HIGHS FROM THE LOW-MID 60S NW RANGING TO 70-75 SOUTHEAST. -GIH THE UPPER LOW...NEAR THE GREAT LAKES EARLY THIS MORNING...WILL QUICKLY WEAKEN AS IT OPENS UP AND MOVES INTO SOUTHEAST CANADA. IT WILL DRAG A SHEARED VORTICITY AXIS THROUGH THE REGION SATURDAY NIGHT. MOISTURE PROFILES ARE VERY DRY WITH PRECIPITABLE WATERS DROPPING TO AROUND A THIRD OF AN INCH. THEREFORE...THIS FEATURE SHOULD COME THROUGH WITH VERY LITTLE FANFARE OR CLOUDS FOR THAT MATTER. WEAK HIGHER PRESSURE MOVES INTO SOUTHERN MS/AL BY SUNDAY MORNING WITH A RIDGE AXIS EXTENDING NORTHEAST INTO CENTRAL NORTH CAROLINA. CLEARS SKIES AND RATHER LIGHT WINDS SHOULD HELP TEMPS TO FALL INTO THE MID TO UPPER 40S. -JFB && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 250 AM SATURDAY... THE SFC RIDGE SHIFTS TO THE SOUTH AND EAST OF THE AREA DURING THE DAY ON SUNDAY AS THE 850-500 MB FLOW SHIFTS TO A WEST TO WEST NORTH COMPONENT. AFTERNOON LOW LEVEL THICKNESSES WILL RISE TO 1370 M IN RESPONSE. THESE THICKNESS VALUES ARE NEAR CLIMATOLOGY...BUT THE WESTERLY DOWNSLOPE FLOW AND DRY ADIABATIC PROFILES EXTENDING UP TO 850 MB SHOULD ALLOW HIGH TEMPERATURES TO CLIMB INTO THE LOW TO MID 70S...ABOUT 4-5 DEGREES ABOVE NORMAL. SHORTWAVE ENERGY CURRENTLY DIVING SOUTHEAST OUT OF CANADA WILL EVOLVE INTO A HIGHLY AMPLIFIED EASTERN STATES TROUGH BY MONDAY. AS THIS TROUGH UNDERGOES AMPLIFICATION...IT WILL PUSH A STRONG COLD FRONT THROUGH CENTRAL NORTH CAROLINA ON MONDAY. THE EXACT TIMING OF THE FRONT WILL GREATLY AFFECT TEMPERATURES...THUS THE LOW AND HIGH TEMP FORECAST ON MONDAY ARE SOMEWHAT UNCERTAIN. THE GFS SHOWS FROPA THROUGH THE CWA BY 12Z MONDAY...WHILE THE 12Z ECMWF AND 00Z NAM ARE ABOUT 6-8 HOURS SLOWER. THE CURRENT LOW FORECAST FOR MONDAY IS 43-49. IF THE GFS TIMING IS RIGHT...LOWS COULD BE COLDER... PARTICULARLY IN THE WEST. HOWEVER...THE ECMWF TIMING WOULD LIKELY RESULT IN MUCH MILDER LOWS. THE GFS SOLUTION WOULD ALSO KEEP TEMPS IN THE 50S ALL DAY WITH THICKNESSES DROPPING TO 1310M EARLY IN THE DAY AND REMAINING STEADY. THE NORTHWEST DOWNSLOPE FLOW WOULD BE THE ONLY FACTOR THAT WOULD OFFSET THE COLD ADVECTION AND PREVENT EVEN COLDER TEMPS. THE LATER TIMING ON THE ECMWF COULD ALLOW THE EASTERN FORECAST AREA TO CLIMB INTO THE 60S BEFORE THE COLD AIR ADVECTION KICKS IN. FOR NOW WILL GO WITH A VERY UNCERTAIN HIGH TEMP FORECAST OF 58-66...KEEPING IN MIND THE POTENTIAL FOR TEMPS FALLING THROUGH THE 50S IN THE AFTERNOON. THICKNESSES DROP TO BETWEEN 1290-1300M BY TUESDAY MORNING. PAST CASES SHOW THAT THIS ALMOST ALWAYS RESULTS IN TEMPS BELOW FREEZING. HOWEVER...THE CENTER OF THE SFC HIGH WILL BE LOCATED WELL WEST OF THE REGION ACROSS ARKANSAS...SO WINDS WILL LIKELY STAY IN THE 5-10 KT RANGE THROUGH THE NIGHT. THIS COULD KEEP THE LOWS ABOVE FREEZING. HAVE NUDGED LOWS DOWN ABOUT 3 DEGREES... RANGING FROM 33-36. WOULD NOT BE SURPRISED IF FREEZING TEMPS DO COME TO FRUITION DESPITE THE WIND IF THE LOW THICKNESSES VERIFY. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 330 AM SATURDAY... THE DEEP L/W TROUGH OVER THE EASTERN U.S. WILL LIFT E-NE THROUGH THE PERIOD. THIS WILL LEAD TO A SLOW MODERATION OF TEMPERATURES. OVERNIGHT MIN TEMPS WILL REMAIN VERY CHILLY TUESDAY NIGHT AND AGAIN WEDNESDAY NIGHT. POTENTIAL FOR A LIGHT FREEZE TUESDAY NIGHT ACROSS THE NORTHERN COUNTIES. AFTERNOON TEMPERATURES WILL WARM FROM THE MID/UPPER 50S TUESDAY INTO THE MID 60S BY FRIDAY. A SURFACE RIDGE ALIGNED WEST-TO-EAST ACROSS THE REGION WILL BLOCK ANY LOW LEVEL MOISTURE ADVECTION. THUS EXPECT DRY WEATHER THROUGH THE REMAINDER OF THE WORK WEEK. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 740 AM SATURDAY... A SATURATED AIR MASS IN THE LOWEST 5000-8000FT WILL MAINTAIN OVERCAST SKIES AND PATCHES OF LIGHT RAIN OR DRIZZLE OVER CENTRAL NORTH CAROLINA THROUGH 15Z. AN AREA OF LOW PRESSURE WILL BEGIN TO EXIT THE REGION THIS AFTERNOON. WESTERLY WINDS BEHIND THIS SYSTEM WILL FUNNEL DRIER MORE STABLE AIR INTO THE REGION. THIS SHOULD CAUSE CEILINGS TO GRADUALLY LIFT AND DISSIPATE FROM WEST-TO-EAST THIS AFTERNOON. VFR CONDITIONS ARE ANTICIPATED TONIGHT THROUGH WEDNESDAY. BREEZY WINDS EXPECTED MONDAY AS A DRY COLD FRONT CROSSES THE REGION. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...JFB NEAR TERM...JFB/HARTFIELD SHORT TERM...JFB LONG TERM...WSS AVIATION...WSS
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
310 AM PDT MON OCT 27 2008 .SHORT TERM... MARINE LAYER NOT BEHAVING VERY WELL TONIGHT AS GRADIENTS ARE TRENDING A LITTLE MORE OFFSHORE THAN THEY WERE LAST NIGHT. THE BULK OF THE DENSE FOG IS OVER THE CENTRAL COAST WHERE A DENSE FOG ADVISORY IS IN EFFECT THROUGH 8 AM. ACARS SOUNDING OUT OF KLAX SHOWS THE MARINE AT 500 FEET OR BELOW. BUT IT IS 78 DEGREES AT 1000 FEET WHICH WILL MAKE FOR ANOTHER WARM DAY IN THE VLYS AND COASTAL INLAND AREAS. THE COASTAL AREAS WILL REMAIN COOL. SOME HIGH CLOUDS ROTATING AROUND AN UPPER LOW 900 NM WEST OF SFO WILL CREATE PARTLY CLOUDY SKIES FOR SLO AND SBA COUNTIES. DUE TO THE WARM DRY AIR ABOVE THE INVERSION A RED FLAG WARNING WILL CONTINUE TODAY FOR EXTENDED VERY LOW CONDITIONS. TUESDAY THE RIDGE BREAKS DOWN A LITTLE AS A TROF RIDES UP INTO NORTHERN CA. THIS SHOULD LIFT THE MARINE LAYER ENOUGH TO GREATLY REDUCE OR ELIMINATE THE DENSE FOG. HARD TO FIGURE WHY BUT MOS GUIDANCE FORECASTS A 4 TO 5 DEGREE WARM UP OVER MOST AREAS DUE TO A SPIKE IN 950 AND BL TEMPS. THINK THIS IS A LITTLE OVERDONE ESP WITH THE GREATER MARINE LAYER AND ONSHORE FLOW. WEDNESDAY SHOULD BE MUCH LIKE TUESDAY WITH SUNNY SKIES PREVAILING AFTER A ROUND OF MORNING LOW CLOUDS AND FOG. THE SYNOPTIC PATTERN IS A LITTLE MORE STATIC WITH A RIDGE SETTING UP OVER AC AND A DIGGING TROF SETTING UP OVER THE EAST PAC. .LONG TERM... INTERESTING TIMES IN THE EXTENDED FORECAST BUT SOMEWHAT CHALLENGING TO FIGURE OUT HOW INTERESTING. THE GFS AND EC AGREE FAIRLY WELL EXCEPT IN THE CRITICAL WEEKEND PERIOD WHERE EC IS QUICKER THAN THE SLOWER EC. ALL GFS ENSEMBLES TEND TOWARD THE OPERATIONAL GFS. BUT 18Z AND 00Z GFS HAVE TRENDED MUCH WETTER. CONFIDENCE IN THURSDAY AND FRIDAY FORECAST LOOKS GOOD. WITH RIDGE SLOWLY MOVING TO THE EAST AND THE TROF SLOWLY APPROACHING THE COAST THE DAYS WILL SLOWLY COOL. THE MARINE LAYER WILL EXPAND ON THURSDAY. SKIES WILL TURN PARTLY CLOUDY THU AFTERNOON AS MID AND HIGH LEVEL MOISTURE EMBEDDED IN THE SW FLOW AHEAD OF THE TROF STREAMS OVER THE AREA. THE MARINE LAYER MAY WELL BE DISRUPTED BY THE UPPER LEVEL CLOUDS FRIDAY AND WITH ALL THE CLOUDS WORDED THE FORECAST AS PARTLY TO MOSTLY CLOUDY WHICH WILL LIKELY WILL BEST DESCRIBE THE DAY. SATURDAY AND SUNDAY WILL BE COOLER AS THE LOW APPROACHES. AS MENTIONED ABOVE THE GFS IS SLOWER AND FAIRLY WET AND THE EC IS FASTER AND DRIER. IT LOOKS MORE AND MORE LIKELY THAT THE CENTRAL COAST WILL SEE SOME RAIN THIS WEEKEND BUT THE TIMING UNCERTAINTIES DO NOT ALLOW ANY ONE 6 OR 12 HOUR TIME BLOCK TO HOLD HIGHER THAN SLGT CHC POPS. SOUTH OF POINT CONCEPTION IF THE GFS FINDS ITS SUBTROPICAL MOISTURE PLUME...AS THE GFS IS ADVERTISING...THERE WILL BE RAIN AND MAYBE A DECENT AMOUNT. THE GFS IS SLOWER AND KEEPS ALL THE PRECIP OUT OF THE AREA UNTIL SUNDAY. IT WILL BE INTERESTING TO WATCH THIS SYSTEM EVOLVE. && .AVIATION... 27/1100Z. WILL BE ISSUED WITH THE 12Z TAFS KLAX... KBUR... && .LOX WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING (SEE LAXRFWLOX). DENSE FOG ADVISORY (SEE LAXNPWLOX). && $$ PUBLIC...RORKE AVIATION...SWEET WWW.WEATHER.GOV/LOSANGELES
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
931 PM PDT SUN OCT 26 2008 .UPDATE...DENSE FOG IS DEVELOPING ALONG THE CENTRAL COAST...WHILE THE MARINE LAYER IS SLOWER TO DEVELOP TONIGHT AT COASTAL LOCATIONS SOUTH OF POINT CONCEPTION. A DENSE FOG ADVISORY HAS BEEN ISSUED FOR THE CENTRAL COAST...BUT THERE IS SOME CONCERN ABOUT THE HIGH LEVEL MOISTURE OFF THE COAST INTERFERING AND DISSIPATING THE FOG MUCH EARLIER THAN EXPECTED. SURFACE GRADIENTS ARE TRENDING MORE OFFSHORE VERSUS LAST NIGHT SOUTH OF POINT CONCEPTION DELAYING THE POSSIBILITY OF DENSE FOG UNTIL LATER TONIGHT. ALL MODEL GUIDANCE FOR KLAX...KOXR...AND KLGB INDICATE NO DENSE FOG AT ALL. HOWEVER WITH MARINE LAYER INVERSION AROUND 500 FEET FROM LATEST ACARS SOUNDING AT KLAX...DENSE FOG CANNOT BE RULED OUT. PACKAGE WILL BE LEFT ALONE FOR NOW. A TROUGH OUT NEAR 35 N AND 135 W WILL SLOWLY LIFT OVER NORTHERN CALIFORNIA THROUGH MIDWEEK. WITH UPPER-LEVEL SOUTHEAST FLOW OVER THE AREA...SOUTHWEST CALIFORNIA WILL LIKELY SEE AN INCREASE IN MID AND HIGH LEVEL MOISTURE ASSOCIATED WITH THIS TROUGH. MODELS CONTINUE TO DOWNPLAY ANY INCREASE IN THE MARINE LAYER OR ANY CONVECTIVE DEVELOPMENT WITH THIS TROUGH. MOISTURE WILL INCREASE SLIGHTLY OVER THE AREA FOR MIDWEEK AND TEMPERATURES WILL LIKELY COOL SLIGHTLY THROUGH MIDWEEK...BUT NO OTHER MAJOR ISSUES ARE EXPECTED. LARGER STORY SEEMS TO BE A BETTER AGREEMENT BETWEEN THE GFS AND ECMWF SOLUTIONS FOR A POSSIBLE STORM SYSTEM WITH A TROPICAL TAP FOR LATE WEEK. DISAGREEMENTS STILL OCCUR WITH THE STRENGTH OF THE TROUGH AND ITS EXACT TRACK...BUT THIS DEEP STORM STILL LOOKS IMPRESSIVE ON WATER VAPOR IMAGERY OVER THE GULF OF ALASKA AND CENTRAL PACIFIC. ECWMF AND GFS BRING A FAIRLY DECENT TROPICAL TAP AHEAD OF THE SYSTEMS COLD FRONT WITH DECENT SOUTHWEST FLOW. THE 18Z OPERATIONAL GFS SOLUTION SEEMS TO BE THE MOST AGGRESSIVE OF THE SOLUTIONS AND THE OUTLIER...BUT BOTH THE OPERATIONAL GFS AND ECMWF SOLUTION WOULD BRING PRECIPITATION TO THE AREA. 850 MB MIXING RATIOS IN BOTH SOLUTIONS INCREASE TO 6 G/KG OR ABOVE DURING THE SAME TIME PERIOD WITH DECENT AMOUNTS OF JET DYNAMICS AND AMPLE WARM AIR ADVECTION OVER THE AREA. PACKAGE WILL LIKELY NEED TO BE COOLED FURTHER AND POPS AND SKY MAY NEED TO BE INCREASED FOR LATE WEEK. && .PREV DISCUSSION... /ISSUED 200 PM PDT SUN OCT 26 2008/ SHORT TERM (TONIGHT THROUGH WEDNESDAY)...12Z GFS/WRF ARE IN VERY GOOD AGREEMENT WITH OVERALL SYNOPTIC PATTERN. AT UPPER LEVELS... RIDGE REMAINS CENTERED OVER ARIZONA WHILE A WEAK LOW OVER THE EASTERN PACIFIC MOVES UP AND AROUND THE RIDGE INTO NORTHERN CALIFORNIA BY WEDNESDAY. NEAR THE SURFACE...DIURNAL GRADIENT TRENDS WILL CONTINUE THROUGH WEDNESDAY...ALTHOUGH MODELS INDICATE SLIGHTLY STRONGER OFFSHORE GRADIENTS MONDAY MORNING AND TUESDAY MORNING. OVERALL...END RESULT FOR THE SHORT TERM FORECAST WILL BE ONLY MINOR CHANGES THROUGH WEDNESDAY. DESPITE THE INDICATED STRONGER OFFSHORE GRADIENTS THE NEXT COUPLE OF MORNINGS...THE MARINE LAYER SHOULD CONTINUE TO AFFECT THE COASTAL ZONES AS THE OFFSHORE FLOW WILL NOT OVERCOME THE STRONG INVERSION. SO...WILL LIKELY CONTINUE TO SEE DENSE FOG NEAR THE IMMEDIATE COAST THROUGH TUESDAY MORNING THEN A DEEPER MARINE INVERSION WEDNESDAY MORNING AS THE UPPER TROUGH MOVES INTO NORTHERN CALIFORNIA. OTHER THAN THE COASTAL STRATUS AND FOG...SKIES SHOULD REMAIN MOSTLY CLEAR THROUGH WEDNESDAY. AS FOR TEMPS...MONDAY SHOULD VERY SIMILAR TO THIS AFTERNOON... ALTHOUGH THE STRONGER OFFSHORE GRADIENTS MAY RESULT IN SOME MINOR WARMING ACROSS THE COASTAL VALLEYS AND INLAND AREAS OF THE COASTAL PLAIN. ON TUESDAY AND WEDNESDAY...WILL EXPECT SLIGHT COOLING ALL AREAS AS UPPER RIDGE WEAKENS AND ONSHORE FLOW STRENGTHENS IN THE AFTERNOON HOURS. NO SIGNIFICANT WIND ISSUES ARE EXPECTED THROUGH WEDNESDAY. LONG TERM (THURSDAY THROUGH SUNDAY)...FINALLY...EXTENDED MODELS HAVE COME INTO RELATIVELY GOOD AGREEMENT WITH THE SYNOPTIC PATTERN THROUGH THE PERIOD...WITH THE MAIN FOCUS ON A UPPER LOW OVER THE EASTERN PACIFIC. FOR THURSDAY/FRIDAY...ECMWF/GFS INDICATE THE UPPER RIDGE MAY STRENGTHEN A LITTLE ACROSS THE SOUTHWEST. NORMALLY...WOULD EXPECT A SLIGHT INCREASE IN TEMPS FOR THURSDAY. HOWEVER...WITH THE AREA UNDER A SOUTH TO SOUTHWEST FLOW...WILL EXPECT AN INCREASE IN MID AND HIGH CLOUDS WHICH SHOULD HELP TO TEMPER ANY WARMING EFFECTS. IN ADDITION...THE MARINE LAYER AND ONSHORE FLOW SHOULD TEMPER ANY WARMING FOR AREAS WEST OF THE MOUNTAINS. FOR SATURDAY/SUNDAY...THE UPPER LOW FINALLY STARTS TO MOVE TO THE EAST...AFFECTING CALIFORNIA. AT THIS TIME...BOTH THE GFS AND ECMWF INDICATE THE POTENTIAL FOR SOME LIGHT PRECIP ACROSS SLO/SBA COUNTIES...AND MAYBE EVEN VTU/LAX COUNTIES BY SUNDAY. AT THIS TIME...WILL KEEP FORECAST AS IS WITH ONLY SLIGHT CHANCE POPS MENTIONED FOR SLO/SBA COUNTIES. EITHER WAY...THINGS SHOULD BE MUCH COOLER NEXT WEEKEND WITH PARTLY TO MOSTLY CLOUDY SKIES. && .AVIATION...26/2327Z. AT INLAND TERMINALS...VFR CONDITIONS ARE EXPECTED THROUGHOUT THE PERIOD. AT COASTAL TERMINALS...MVFR CONDITIONS SHOULD ARRIVE BETWEEN 02Z AND 06Z...AND WITHIN ONE TO THREE HOURS CEILINGS AND VISIBILITIES WILL FALL INTO THE LIFR CATEGORY. ALONG THE CENTRAL COAST...IT IS LIKELY THAT INCREASING HIGH LEVEL MOISTURE WILL CAUSE THE DENSE FOG TO DISSIPATE AFTER 12Z MONDAY. SOUTH OF KOXR...A STRONG MARINE INVERSION IN PLACE COULD KEEP THE COASTAL TERMINALS IN THE IFR TO MVFR CATEGORIES THROUGH AT LEAST 16Z...WITH A CHANCE THAT VFR CONDITIONS MAY NOT DEVELOP UNTIL AROUND 19Z. KLAX...VFR CONDITIONS WILL PERSIST THROUGH AT LEAST 04Z TONIGHT...OR AS LATE 06Z. LIFR CONDITIONS WILL LIKELY DEVELOP AROUND 10Z...BUT THERE IS A 30 PERCENT CHANCE THAT LIFR CONDITIONS MAY NOT OCCUR UNTIL 12Z. MVFR TO VFR CONDITIONS SHOULD DEVELOP AROUND 16Z...BUT THERE IS A 40 PERCENT CHANCE THAT VFR CONDITIONS MAY DEVELOP UNTIL 19Z ON MONDAY. KBUR...VFR CONDITIONS WILL PERSIST THROUGHOUT THE PERIOD...WITH NO WIND ISSUES EXPECTED. && .LOX WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING (SEE LAXRFWLOX). SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS (SEE LAXMWWLOX). DENSE FOG ADVISORY (SEE LAXNPWLOX). && $$ PUBLIC...HALL/THOMPSON AVIATION...HALL WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS BUFFALO NY
444 AM EDT MON OCT 27 2008 .SYNOPSIS... A NORTHWEST FLOW OF UNSEASONABLY COLD AIR WILL SWEEP ACROSS THE GREAT LAKES REGION THROUGH MIDWEEK AND PRODUCE THE SEASON`S FIRST BOUT OF LAKE EFFECT PRECIPITATION. THIS SHOULD MAINLY BE IN THE FORM OF RAIN TODAY AND TONIGHT ALTHOUGH GRADUALLY TRANSITIONING TO SNOW LATER TUESDAY INTO WEDNESDAY AS TEMPERATURES COOL ALTHOUGH ANY ACCUMULATION SHOULD BE LIMITED TO HIGHER ELEVATIONS. THERE MAY BE ADDITIONAL SNOWFALL EAST OF LAKE ONTARIO TUESDAY AFTERNOON AND NIGHT IN ASSOCIATION WITH LOW PRESSURE MOVING NORTH ACROSS NEW ENGLAND. MUCH MILDER WEATHER WILL MOVE BACK IN LATER IN THE WEEK AS THIS SYSTEM LIFTS OUT. && .NEAR TERM /THROUGH TONIGHT/... THE FAIRLY WIDESPREAD SYNOPTIC BASED SHOWERS FROM THE OVERNIGHT WILL TAPER OFF ACROSS THE MAJORITY OF THE REGION DURING THE NEXT SEVERAL HOURS...WITH LAKE EFFECT WILL FINALLY GET GOING OFF LAKE ERIE. THE LAKE EFFECT HAS BEEN DELAYED DUE TO A STALLED FRONTAL BOUNDARY THAT APPEARS TO BE SHEARING OUT ACROSS LAKE ERIE AS OF THE WRITING OF THIS DISCUSSION (0730Z). AS A RESULT...THE LOW LEVEL FLOW HAS BEEN MORE SOUTHERLY. THIS IS NOW CHANGING AS COLDER AIR IS MAKING ITS WAY OVER THE LAKE AND THE MESOSCALE PROCESS IS UNDERWAY. THE H85 TEMPS FOR THE BULK OF THE NIGHT WERE 2 TO 4C OVER LK ERIE...BUT UPSTREAM AIRCRAFT SOUNDINGS ARE NOW SUGGESTING THAT ZERO TO -2C AIR IS MAKING ITS OVER THE LAKE. AS OF 08Z...A BAND IS ORGANIZING ON A 220 FLOW. THIS WILL TAKE THE INITIAL LAKE EFFECT PCPN INTO SITES WELL NORTH OF BUFFALO. THE LOW LEVEL FLOW IS EXPECTED TO SETTLE BACK TO AROUND 240 SHORTLY AFTER DAYBREAK THOUGH...BRINGING THE LAKE EFFECT RAIN SHOWERS INTO BUFFALO AND THE IAG FRONTIER. AS THE DAY PROGRESSES...THIS FLOW WILL CONTINUE TO VEER TO MORE OF A 250-260 FLOW WITH THE ACTIVITY EVENTUALLY HEADING SOUTH OF BUFFALO. THE POTENTIAL FOR SNOW OVER THE HIGHER TERRAIN SOUTH OF BUFFALO HAS ESSENTIALLY DROPPED TO A NEGLIGIBLE POSSIBILITY. ONE...BECUASE THE MAIN BAND ON A 220 FLOW DURING THE PRE DAWN HOURS WILL NOT AFFECT THE HIGHER TERRAIN...AND TWO...TEMPS ALOFT ARE A COUPLE DEGREES TOO HIGH. THE FLOW WILL VEER BY DAYBREAK...BUT EVEN WITH PART OF THE BAND POSSIBLY COMING ONSHORE IN CHAUTAUQUA COUNTY...H85 TEMPS OF -4 TO -5C SHOULD NOT ALLOW FOR SNOW. GRAUPEL? POSSIBLY...ESPECIALLY ALOFT. LAKE INDUCED CAPES >600 J/KG SHOULD BE ABLE TO `SUPPORT` A MIXED PHASE CLOUD TO NEAR 10K FEET WHERE THE GRAUPEL WILL BE MOST LIKELY. COMBINE THIS WITH LAKE INDUCED EL `S ARND 17-20K FT...AND YOU HAVE SUFFICIENT CLOUD DEPTH AND ENOUGH MIXED PHASE PCPN TO GENERATE SOME LAKE INDUCED LIGHTNING. THIS WILL MAINLY BE THE CASE WITHIN THE BAND ITSELF...SO SLGT/CHC MENTION OF THIS WILL REMAIN THE FORECAST. OFF LAKE ONTARIO...A SOUTH TO SOUTHWEST FLOW SHOULD ALSO PROMOTE SOME LAKE EFFECT RAIN SHOWERS FOR SITES GENERALLY NORTH OF WATERTOWN. THIS LAKE EFFECT IS NOT EXPECTED TO BE AS ORGANIZED THOUGH...AS GREATER SHEAR BELOW H85 AND A SHORTER FETCH SHOULD PREVENT A WELL ORGANIZED BAND FROM FORMING. THIS WILL ALSO WORK AGAINST ANY LAKE INDUCED LIGHTNING...ALTHOUGH NOT OUT OF THE QUESTION. THE REMAINDER OF WESTERN AND NORTH CENTRAL NEW YORK WILL HAVE SOME LEFTOVER RAIN SHOWERS EARLY THIS MORNING AS A RESULT OF SOME CHANNELLED VORTICITY AND DEPARTING UPPER LEVEL JET DYNAMICS. THESE AREAS SHOULD NOTE A DRYING TREND DURING THE COURSE OF THIS MORNING WITH SOME SUN POSSIBLE FROM TIME TO TIME AS LOW LEVEL RIDGING WILL CROSS THE REGION. FOR TONIGHT...THE PASSING OF A WEAK SFC WAVE WILL VEER WINDS TO A NORTH-NORTHWEST DIRECTION WHILE H85 TEMPS OF -2C THIS EVENING WILL DROP OFF TO ARND -4C BY DAYBREAK. MULTIPLE BANDS OF LAKE EFFECT RAIN SHOWERS WILL THEN DEVELOP SOUTH OF LAKE ONTARIO AND ALSO WELL SOUTH OF BUFFALO. WILL USE LIKELY TO CAT POPS FOR THESE AREAS. AGAIN...IT SHOULD BE TOO WARM FOR LAKE EFFECT SNOW...ALTHOUGH CANNOT RULE IT OUT ON THE HIGHER TERRAIN SOUTH OF BUFFALO TOWARDS TUESDAY MORNING. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... THIS PERIOD WILL FEATURE A NORTHWEST FLOW OF VERY COLD AIR CROSSING THE LAKES...WITH THE ADDITIONAL COMPLICATION OF A COASTAL STORM EXPLODING OVER NEW ENGLAND. WESTERN AREAS WILL JUST DEAL WITH SOME LAKE EFFECT PRECIPITATION.... ESPECIALLY IN UPSLOPE AREAS SOUTHEAST OF THE LAKES. 850 MB TEMPS WILL STILL BE MILD ENOUGH (-4C TO -6C) FOR ANYTHING TO FALL AS MOSTLY RAIN DURING THE DAY TUESDAY AT LOWER ELEVATIONS WITH PERHAPS A SLUSHY INCH OR TWO AT HIGHEST ELEVATIONS OF THE SOUTHERN TIER. THEY DO DROP TO -8C OR LOWER TUES NT AND WED AM...SO ANYTHING WOULD BE SNOW...BUT IT DOES LOOK ONLY SCATTERED ACROSS MOST AREAS WITH PERHAPS AN INCH OR TWO AT HIGHER ELEVATIONS. WILL HAVE TO KEEP AN EYE ON ANY HURON PLUME BRUSHING CHAUT CO WITH MORE ACCUM ON THE RIDGES. RIDGING MOVES IN WEDNESDAY AND DIMINISHES THE ACTIVITY...ENDING IT BY WED EVENING. NOW...MODELS ARE COMING INTO BETTER AGREEMENT WITH DEVELOPING A MAJOR COASTAL STORM OVER NEW ENG TUES MORNING AND LIFTING IT TO QUEBEC BY WED AM. THIS SOLUTION HAS BEEN EVIDENT ON THE ECMWF FOR DAYS...BUT GFS HAS FINALLY COME INTO LINE. THIS STORM WILL DEEPEN RAPIDLY AS IT MOVES NORTH AND PULL COLD AIR INTO IT...WITH LARGE WRAPAROUND AREA OF DEFORMATION ZONE PRECIPITATION...WHICH SHOULD TURN QUICKLY TO SNOW AS IT COOLS...EVEN AT LOWER ELEVATIONS. QUESTION IS HOW FAR WEST THIS SETS UP. GFS AND HPC SHOW A SHARP CUTOFF OF HEAVY SNOW ACROSS ST LAWR AND LEWIS COS...BUT NAM IS FURTHER WEST AND WOULD GIVE BOTH JEFF/LEWIS AND E OSW COUNTY HEAVY SNOW. THERE WILL BE A MAX OF A FOOT FOR MORE SOMEWHERE...LOOKS NOW LIKE THE ADIRONDACKS BUT IT WILL BE CLOSE. WILL AWAIT ONE MORE RUN TO HOIST ANY FLAGS AS THIS SOLUTION IS RATHER SUDDEN...INCLUDED 1-4 INCHES THERE FOR NOW...HIGHEST IN LEWIS CO. IN ANY CASE...AS WINDS BACK TO WNW TUES NT AND WED AM...THERE SHOULD BE A DECENT LK EFFECT SNOW SITUATION SETTING UP FROM WAYNE TO OSW COUNTIES AS AIRMASS WILL BE COLD ENOUGH (-9C 850 MB) EVEN AT LOWER ELEVATIONS. FUTURE SHIFTS WILL NEED TO MONITOR THIS. IT WILL LAST THRU WED AND GRADUALLY TAPER OFF WED NT. && .LONG TERM /THURSDAY THROUGH SUNDAY/... MAJOR PATTERN SHIFT DURING THIS PERIOD AS UPPER LOW LIFTS OUT AND FAST WEST TO SOUTHWEST FLOW OF MUCH MILDER AIR SWEEPS IN ACROSS LOWER LAKES THURS AND FRI. 850 MB TEMPS RISE TO +8C OR SO...RAISED THURS TEMPS A BIT...AND HELD FRI`S IN M-U 50S. SHOULD BE FAIRLY PLEASANT HALLOWEEN EVENING WITH TEMPS NEAR 50 AND DRY CONDITIONS. ANOTHER UPPER TROF SAGS FAR ENOUGH SOUTH TO SEND A WEAKENING COLD FRONT ACROSS THE AREA FRI NT WITH CHC POPS BUT FRONT SHOULD GET FAR ENOUGH SOUTH TO ALLOW FOR SOME CLEARING SATURDAY...HELD CHC POPS SRN TIER ONLY IN MORNING. MUCH COOLER SAT WITH 850 MB TEMPS OF -8C BUT N-NE FLOW AND SHEAR SHOULD NEGATE ANY LK EFFECT. VERY COLD SAT NT BUT SUNDAY LOOKING PLEASANT AT THIS STAGE WITH HIGH CRESTING OVER EASTERN LAKES...SUNSHINE AND TEMPS REBOUNDING TO 50. LONGER RANGE LOOKS MILD WITH ZONAL TO SLIGHT RIDGING MOST OF NEXT WEEK. && .AVIATION /09Z MONDAY THROUGH FRIDAY/... VFR CONDITIONS WILL BE IN PLACE THROUGH THE MUCH OF THE REMAINDER OF THE OVERNIGHT...ALTHOUGH SOME LAKE EFFECT RAIN SHOWERS WILL DEVELOP TOWARDS DAYBREAK OFF OF LAKE ERIE. THIS ACTIVITY COULD HELP TO REDUCE CIGS TO MVFR LEVELS AS RAIN SHOWERS WILL BECOME COMMON FOR KBUF IN PARTICULAR. BEFORE WE GET THE LAKE EFFECT TO DEVELOP THOUGH...A NEARLY STALLED FRONTAL BOUNDARY OVER LAKE ERIE WILL HELP TO GENERATE SOME SHOWERS AND POSSIBLY ANOTHER THUNDERSTORM. LIGHT DETECTION DISPLAYS WERE STILL SHOWING SOME CLOUD TO SFC STRIKES OVER LAKE ERIE AS OF 0550Z. AS MONDAY MORNING UNFOLDS...VFR CONDITIONS WILL REMAIN IN PLACE FOR THE MAJORITY OF WRN AND NORTH CENTRAL NEW YORK. THE EXCEPTION WILL AGAIN BE FOUND IN THE VCNTY OF KBUF WHERE CIGS/VSBYS WILL RANGE FROM MVFR TO OCCASIONALLY IFR IN STEADY LAKE RAIN SHOWERS. THESE SHOWERS MAY BE ACCOMPANIED BY AN OCCASIONAL RUMBLE OF THUNDER. AS WINDS VEER MORE TO THE WEST DURING THE COURSE OF THE DAY...THE LAKE SHOWERS/LOWER CIGS WILL SETTLE TO THE SOUTH TOWARDS KJHW. THIS WILL LEAD TO MVFR TO OCCASIONALLY IFR CIGS FOR KJHW FOR THE AFTERNOON INTO MONDAY NIGHT. FOR MONDAY NIGHT...VFR CONDITIONS WILL PREVAIL OVER THE REGION. A CHILLY NORTH TO NORTHWEST FLOW WILL KEEP ANY LAKE INDUCED MVFR CIGS/VSBYS CONFINED TO SITES SUCH AS KJHW...ALTHOUGH MVFR CONDITIONS WILL NOT BE OUT OF THE QUESTION FOR KROC. OUTLOOK... TUESDAY...MVFR/AREAS OF IFR IN LAKE EFFECT RAIN AND SNOW SHOWERS. WEDNESDAY...MVFR/AREAS IFR IN LAKE EFFECT SNOW SHOWERS SE OF THE LAKES. THURSDAY...VFR. FRIDAY...OCCASIONAL MVFR IN SHOWERS. && .MARINE... SMALL CRAFT ADVISORIES WILL REMAIN IN EFFECT TODAY FOR ALL OF THE NEARSHORE WATERS OF BOTH LAKES ERIE AND ONTARIO AS A DEEP SOUTHWESTERLY FLOW WILL BE IN PLACE. THE FRESH TO STRONG SOUTHWESTERLIES TODAY WILL PRODUCE WAVES OF 4 TO 7 FEET ON LAKE ERIE (LONG FETCH) WITH WAVES AVERAGING CLOSER TO 3 TO 5 FEET ON THE NEARSHORE WATERS OF LAKE ONTARIO. THE HIGHEST WAVES ON LAKE ONTARIO WILL BE FOUND WELL OFFSHORE...EXCEPT NORTH OF MEXICO BAY WHERE THE HIGHEST WAVES WILL BE CLOSER TO SHORE. THE WINDS WILL SUBSIDE LATE TODAY AND EARLY TONIGHT OVER LAKE ONTARIO AS A WEAK SFC WAVE WILL PASS OVER THE LAKE. THIS WILL ALLOW BOTH WINDS AND WAVES TO TEMPORARILY DROP BELOW SMALL CRAFT CRITERIA...BUT THE SAME WILL NOT HOLD TRUE FOR LAKE ERIE. WHILE THE WINDS WILL BECOME NORTHERLY ON BOTH LAKES...THE NORTHERLY WINDS WILL BE MODERATE TO FRESH ON LAKE ERIE WITH WAVES AVERAGING 3 TO 5 FEET. NORTHWEST WINDS WILL INCREASE AGAIN DURING TUESDAY AND MAY REACH GALE FORCE ON MUCH OF LAKE ONTARIO IN RESPONSE TO THE STRONG SURFACE LOW LIFTING NORTH ACROSS NEW ENGLAND INTO QUEBEC. THIS LOW WILL TIGHTEN THE PRESSURE GRADIENT ACROSS THE LOWER GREAT LAKES...AND DRAW DOWN MUCH COLDER AIR WHICH WILL STEEPEN THE LOW LEVEL LAPSE RATES OVER THE WARM LAKE WATERS AND ALLOW FOR EFFICIENT MOMENTUM TRANSFER OF HIGHER WINDS DOWN TO THE SURFACE. WINDS ARE EXPECTED TO DIMINISH THURSDAY AS SURFACE HIGH PRESSURE BUILDS INTO THE REGION. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS AFTERNOON FOR LEZ020. SMALL CRAFT ADVISORY UNTIL 2 AM EDT TUESDAY FOR LEZ040-041. SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS AFTERNOON FOR LOZ042>045. && $$ SYNOPSIS...SFM NEAR TERM...RSH SHORT TERM...SFM LONG TERM...SFM AVIATION...RSH MARINE...RSH/SFM
AREA FORECAST DISCUSSION
NWS BUFFALO NY
411 AM EDT MON OCT 27 2008 .SYNOPSIS... A NORTHWEST FLOW OF UNSEASONABLY COLD AIR WILL SWEEP ACROSS THE GREAT LAKES REGION THROUGH MIDWEEK AND PRODUCE THE SEASON`S FIRST BOUT OF LAKE EFFECT PRECIPITATION. THIS SHOULD MAINLY BE IN THE FORM OF RAIN TODAY AND TONIGHT ALTHOUGH GRADUALLY TRANSITIONING TO SNOW LATER TUESDAY INTO WEDNESDAY AS TEMPERATURES COOL ALTHOUGH ANY ACCUMULATION SHOULD BE LIMITED TO HIGHER ELEVATIONS. THERE MAY BE ADDITIONAL SNOWFALL EAST OF LAKE ONTARIO TUESDAY AFTERNOON AND NIGHT IN ASSOCIATION WITH LOW PRESSURE MOVING NORTH ACROSS NEW ENGLAND. MUCH MILDER WEATHER WILL MOVE BACK IN LATER IN THE WEEK AS THIS SYSTEM LIFTS OUT. && .NEAR TERM /THROUGH TONIGHT/... THE FAIRLY WIDESPREAD SYNOPTIC BASED SHOWERS FROM THE OVERNIGHT WILL TAPER OFF ACROSS THE MAJORITY OF THE REGION DURING THE NEXT SEVERAL HOURS...WITH LAKE EFFECT WILL FINALLY GET GOING OFF LAKE ERIE. THE LAKE EFFECT HAS BEEN DELAYED DUE TO A STALLED FRONTAL BOUNDARY THAT APPEARS TO BE SHEARING OUT ACROSS LAKE ERIE AS OF THE WRITING OF THIS DISCUSSION (0730Z). AS A RESULT...THE LOW LEVEL FLOW HAS BEEN MORE SOUTHERLY. THIS IS NOW CHANGING AS COLDER AIR IS MAKING ITS WAY OVER THE LAKE AND THE MESOSCALE PROCESS IS UNDERWAY. THE H85 TEMPS FOR THE BULK OF THE NIGHT WERE 2 TO 4C OVER LK ERIE...BUT UPSTREAM AIRCRAFT SOUNDINGS ARE NOW SUGGESTING THAT ZERO TO -2C AIR IS MAKING ITS OVER THE LAKE. AS OF 08Z...A BAND IS TRYING TO ORGANIZE ON A 220 FLOW. THIS WOULD TAKE THE INITIAL LAKE EFFECT PCPN INTO SITES GENERALLY NORTH OF BUFFALO. THE LOW LEVEL FLOW IS EXPECTED TO SETTLE BACK TO AROUND 240 BY DAYBREAK THOUGH...BRINGING THE LAKE EFFECT RAIN SHOWERS INTO BUFFALO AND THE IAG FRONTIER. AS THE DAY PROGRESSES...THIS FLOW WILL CONTINUE TO VEER TO MORE OF A 250-260 FLOW WITH THE ACTIVITY EVENTUALLY HEADING SOUTH OF BUFFALO. WHILE THERE IS LITTLE DOUBT THAT A FAIRLY WELL ORGANIZED BAND OF LAKE EFFECT WILL GET GOING...TEMPS ARE A COUPLE DEGREES TOO HIGH FOR LAKE EFFECT SNOW. CANNOT RULE OUT SOME GRAUPEL OR WET FLAKES ACROSS THE HIGHER TERRAIN THIS MORNING...BUT WITH THE BAND INITIALLY ALIGNED MORE NORTH TO SOUTH...EVEN THIS SCENARIO WILL HAVE TROUBLE VERIFYING. IN EITHER CASE...HAVE CUT WAY BACK ON ANY SNOWFALL FOR THOSE HIGHER ELEVATIONS. AS MENTIONED...THERE WILL STILL LIKELY BE SOME GRAUPEL AROUND. THIS WILL ESPECIALLY BE THE CASE ALOFT WHERE LAKE INDUCED CAPES >600 J/KG SHOULD BE ABLE TO `SUPPORT` A MIXED PHASE CLOUD TO NEAR 10K FEET WHERE THE GRAUPEL WOULD MOST LIKELY BE. COMBINE THIS WITH LAKE INDUCED EL `S ARND 17-20K FT...AND YOU HAVE SUFFICIENT CLOUD DEPTH AND ENOUGH MIXED PHASE PCPN TO GENERATE SOME LAKE INDUCED LIGHTNING. THIS WILL MAINLY BE THE CASE WITHIN THE BAND ITSELF...SO SLGT/CHC MENTION OF THIS WILL REMAIN THE FORECAST. OFF LAKE ONTARIO...A SOUTH TO SOUTHWEST FLOW SHOULD ALSO PROMOTE SOME LAKE EFFECT RAIN SHOWERS FOR SITES GENERALLY NORTH OF WATERTOWN. THIS LAKE EFFECT IS NOT EXPECTED TO BE AS ORGANIZED THOUGH...AS GREATER SHEAR BELOW H85 AND A SHORTER FETCH SHOULD PREVENT A WELL ORGANIZED BAND FROM FORMING. THIS WILL ALSO WORK AGAINST ANY LAKE INDUCED LIGHTNING...ALTHOUGH NOT OUT OF THE QUESTION. THE REMAINDER OF WESTERN AND NORTH CENTRAL NEW YORK WILL HAVE SOME LEFTOVER RAIN SHOWERS EARLY THIS MORNING AS A RESULT OF SOME CHANNELLED VORTICITY AND DEPARTING UPPER LEVEL JET DYNAMICS. THESE AREAS SHOULD NOTE A DRYING TREND DURING THE COURSE OF THIS MORNING WITH SOME SUN POSSIBLE FROM TIME TO TIME AS LOW LEVEL RIDGING WILL CROSS THE REGION. FOR TONIGHT...THE PASSING OF A WEAK SFC WAVE WILL VEER WINDS TO A NORTH-NORTHWEST DIRECTION WHILE H85 TEMPS OF -2C THIS EVENING WILL DROP OFF TO ARND -4C BY DAYBREAK. MULTIPLE BANDS OF LAKE EFFECT RAIN SHOWERS WILL THEN DEVELOP SOUTH OF LAKE ONTARIO AND ALSO WELL SOUTH OF BUFFALO. WILL USE LIKELY TO CAT POPS FOR THESE AREAS. AGAIN...IT SHOULD BE TOO WARM FOR LAKE EFFECT SNOW...ALTHOUGH CANNOT RULE IT OUT ON THE HIGHER TERRAIN SOUTH OF BUFFALO TOWARDS TUESDAY MORNING. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... THIS PERIOD WILL FEATURE A NORTHWEST FLOW OF VERY COLD AIR CROSSING THE LAKES...WITH THE ADDITIONAL COMPLICATION OF A COASTAL STORM EXPLODING OVER NEW ENGLAND. WESTERN AREAS WILL JUST DEAL WITH SOME LAKE EFFECT PRECIPITATION.... ESPECIALLY IN UPSLOPE AREAS SOUTHEAST OF THE LAKES. 850 MB TEMPS WILL STILL BE MILD ENOUGH (-4C TO -6C) FOR ANYTHING TO FALL AS MOSTLY RAIN DURING THE DAY TUESDAY AT LOWER ELEVATIONS WITH PERHAPS A SLUSHY INCH OR TWO AT HIGHEST ELEVATIONS OF THE SOUTHERN TIER. THEY DO DROP TO -8C OR LOWER TUES NT AND WED AM...SO ANYTHING WOULD BE SNOW...BUT IT DOES LOOK ONLY SCATTERED ACROSS MOST AREAS WITH PERHAPS AN INCH OR TWO AT HIGHER ELEVATIONS. WILL HAVE TO KEEP AN EYE ON ANY HURON PLUME BRUSHING CHAUT CO WITH MORE ACCUM ON THE RIDGES. RIDGING MOVES IN WEDNESDAY AND DIMINISHES THE ACTIVITY...ENDING IT BY WED EVENING. NOW...MODELS ARE COMING INTO BETTER AGREEMENT WITH DEVELOPING A MAJOR COASTAL STORM OVER NEW ENG TUES MORNING AND LIFTING IT TO QUEBEC BY WED AM. THIS SOLUTION HAS BEEN EVIDENT ON THE ECMWF FOR DAYS...BUT GFS HAS FINALLY COME INTO LINE. THIS STORM WILL DEEPEN RAPIDLY AS IT MOVES NORTH AND PULL COLD AIR INTO IT...WITH LARGE WRAPAROUND AREA OF DEFORMATION ZONE PRECIPITATION...WHICH SHOULD TURN QUICKLY TO SNOW AS IT COOLS...EVEN AT LOWER ELEVATIONS. QUESTION IS HOW FAR WEST THIS SETS UP. GFS AND HPC SHOW A SHARP CUTOFF OF HEAVY SNOW ACROSS ST LAWR AND LEWIS COS...BUT NAM IS FURTHER WEST AND WOULD GIVE BOTH JEFF/LEWIS AND E OSW COUNTY HEAVY SNOW. THERE WILL BE A MAX OF A FOOT FOR MORE SOMEWHERE...LOOKS NOW LIKE THE ADIRONDACKS BUT IT WILL BE CLOSE. WILL AWAIT ONE MORE RUN TO HOIST ANY FLAGS AS THIS SOLUTION IS RATHER SUDDEN...INCLUDED 1-4 INCHES THERE FOR NOW...HIGHEST IN LEWIS CO. IN ANY CASE...AS WINDS BACK TO WNW TUES NT AND WED AM...THERE SHOULD BE A DECENT LK EFFECT SNOW SITUATION SETTING UP FROM WAYNE TO OSW COUNTIES AS AIRMASS WILL BE COLD ENOUGH (-9C 850 MB) EVEN AT LOWER ELEVATIONS. FUTURE SHIFTS WILL NEED TO MONITOR THIS. IT WILL LAST THRU WED AND GRADUALLY TAPER OFF WED NT. && .LONG TERM /THURSDAY THROUGH SUNDAY/... MAJOR PATTERN SHIFT DURING THIS PERIOD AS UPPER LOW LIFTS OUT AND FAST WEST TO SOUTHWEST FLOW OF MUCH MILDER AIR SWEEPS IN ACROSS LOWER LAKES THURS AND FRI. 850 MB TEMPS RISE TO +8C OR SO...RAISED THURS TEMPS A BIT...AND HELD FRI`S IN M-U 50S. SHOULD BE FAIRLY PLEASANT HALLOWEEN EVENING WITH TEMPS NEAR 50 AND DRY CONDITIONS. ANOTHER UPPER TROF SAGS FAR ENOUGH SOUTH TO SEND A WEAKENING COLD FRONT ACROSS THE AREA FRI NT WITH CHC POPS BUT FRONT SHOULD GET FAR ENOUGH SOUTH TO ALLOW FOR SOME CLEARING SATURDAY...HELD CHC POPS SRN TIER ONLY IN MORNING. MUCH COOLER SAT WITH 850 MB TEMPS OF -8C BUT N-NE FLOW AND SHEAR SHOULD NEGATE ANY LK EFFECT. VERY COLD SAT NT BUT SUNDAY LOOKING PLEASANT AT THIS STAGE WITH HIGH CRESTING OVER EASTERN LAKES...SUNSHINE AND TEMPS REBOUNDING TO 50. LONGER RANGE LOOKS MILD WITH ZONAL TO SLIGHT RIDGING MOST OF NEXT WEEK. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... VFR CONDITIONS WILL BE IN PLACE THROUGH THE MUCH OF THE REMAINDER OF THE OVERNIGHT...ALTHOUGH SOME LAKE EFFECT RAIN SHOWERS WILL DEVELOP TOWARDS DAYBREAK OFF OF LAKE ERIE. THIS ACTIVITY COULD HELP TO REDUCE CIGS TO MVFR LEVELS AS RAIN SHOWERS WILL BECOME COMMON FOR KBUF IN PARTICULAR. BEFORE WE GET THE LAKE EFFECT TO DEVELOP THOUGH...A NEARLY STALLED FRONTAL BOUNDARY OVER LAKE ERIE WILL HELP TO GENERATE SOME SHOWERS AND POSSIBLY ANOTHER THUNDERSTORM. LIGHT DETECTION DISPLAYS WERE STILL SHOWING SOME CLOUD TO SFC STRIKES OVER LAKE ERIE AS OF 0550Z. AS MONDAY MORNING UNFOLDS...VFR CONDITIONS WILL REMAIN IN PLACE FOR THE MAJORITY OF WRN AND NORTH CENTRAL NEW YORK. THE EXCEPTION WILL AGAIN BE FOUND IN THE VCNTY OF KBUF WHERE CIGS/VSBYS WILL RANGE FROM MVFR TO OCCASIONALLY IFR IN STEADY LAKE RAIN SHOWERS. THESE SHOWERS MAY BE ACCOMPANIED BY AN OCCASIONAL RUMBLE OF THUNDER. AS WINDS VEER MORE TO THE WEST DURING THE COURSE OF THE DAY...THE LAKE SHOWERS/LOWER CIGS WILL SETTLE TO THE SOUTH TOWARDS KJHW. THIS WILL LEAD TO MVFR TO OCCASIONALLY IFR CIGS FOR KJHW FOR THE AFTERNOON INTO MONDAY NIGHT. FOR MONDAY NIGHT...VFR CONDITIONS WILL PREVAIL OVER THE REGION. A CHILLY NORTH TO NORTHWEST FLOW WILL KEEP ANY LAKE INDUCED MVFR CIGS/VSBYS CONFINED TO SITES SUCH AS KJHW...ALTHOUGH MVFR CONDITIONS WILL NOT BE OUT OF THE QUESTION FOR KROC. OUTLOOK... TUESDAY...MVFR/AREAS OF IFR IN LAKE EFFECT RAIN AND SNOW SHOWERS. WEDNESDAY...MVFR/AREAS IFR IN LAKE EFFECT SNOW SHOWERS SE OF THE LAKES. THURSDAY...VFR. FRIDAY...OCCASIONAL MVFR IN SHOWERS. && .MARINE... SMALL CRAFT ADVISORIES WILL REMAIN IN EFFECT TODAY FOR ALL OF THE NEARSHORE WATERS OF BOTH LAKES ERIE AND ONTARIO AS A DEEP SOUTHWESTERLY FLOW WILL BE IN PLACE. THE FRESH TO STRONG SOUTHWESTERLIES TODAY WILL PRODUCE WAVES OF 4 TO 7 FEET ON LAKE ERIE (LONG FETCH) WITH WAVES AVERAGING CLOSER TO 3 TO 5 FEET ON THE NEARSHORE WATERS OF LAKE ONTARIO. THE HIGHEST WAVES ON LAKE ONTARIO WILL BE FOUND WELL OFFSHORE...EXCEPT NORTH OF MEXICO BAY WHERE THE HIGHEST WAVES WILL BE CLOSER TO SHORE. THE WINDS WILL SUBSIDE LATE TODAY AND EARLY TONIGHT OVER LAKE ONTARIO AS A WEAK SFC WAVE WILL PASS OVER THE LAKE. THIS WILL ALLOW BOTH WINDS AND WAVES TO TEMPORARILY DROP BELOW SMALL CRAFT CRITERIA...BUT THE SAME WILL NOT HOLD TRUE FOR LAKE ERIE. WHILE THE WINDS WILL BECOME NORTHERLY ON BOTH LAKES...THE NORTHERLY WINDS WILL BE MODERATE TO FRESH ON LAKE ERIE WITH WAVES AVERAGING 3 TO 5 FEET. NORTHWEST WINDS WILL INCREASE AGAIN DURING TUESDAY AND MAY REACH GALE FORCE ON MUCH OF LAKE ONTARIO IN RESPONSE TO THE STRONG SURFACE LOW LIFTING NORTH ACROSS NEW ENGLAND INTO QUEBEC. THIS LOW WILL TIGHTEN THE PRESSURE GRADIENT ACROSS THE LOWER GREAT LAKES...AND DRAW DOWN MUCH COLDER AIR WHICH WILL STEEPEN THE LOW LEVEL LAPSE RATES OVER THE WARM LAKE WATERS AND ALLOW FOR EFFICIENT MOMENTUM TRANSFER OF HIGHER WINDS DOWN TO THE SURFACE. WINDS ARE EXPECTED TO DIMINISH THURSDAY AS SURFACE HIGH PRESSURE BUILDS INTO THE REGION. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS AFTERNOON FOR LEZ020. SMALL CRAFT ADVISORY UNTIL 2 AM EDT TUESDAY FOR LEZ040-041. SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS AFTERNOON FOR LOZ042>045. && $$ SYNOPSIS...SFM NEAR TERM...RSH SHORT TERM...SFM LONG TERM...SFM AVIATION...RSH MARINE...RSH/SFM
AREA FORECAST DISCUSSION
NWS BUFFALO NY
304 AM EDT MON OCT 27 2008 .SYNOPSIS... A NORTHWEST FLOW OF UNSEASONABLY COLD AIR WILL SWEEP ACROSS THE GREAT LAKES REGION THROUGH MIDWEEK AND PRODUCE THE SEASON`S FIRST BOUT OF LAKE EFFECT PRECIPITATION. THIS SHOULD MAINLY BE IN THE FORM OF RAIN TODAY AND TONIGHT ALTHOUGH GRADUALLY TRANSITIONING TO SNOW LATER TUESDAY INTO WEDNESDAY AS TEMPERATURES COOL ALTHOUGH ANY ACCUMULATION SHOULD BE LIMITED TO HIGHER ELEVATIONS. THERE MAY BE ADDITIONAL SNOWFALL EAST OF LAKE ONTARIO TUESDAY AFTERNOON AND NIGHT IN ASSOCIATION WITH LOW PRESSURE MOVING NORTH ACROSS NEW ENGLAND. MUCH MILDER WEATHER WILL MOVE BACK IN LATER IN THE WEEK AS THIS SYSTEM LIFTS OUT. && .NEAR TERM /THROUGH TONIGHT/... A NEARLY STALLED FRONTAL BOUNDARY OVER LAKE ERIE AT 06Z WAS STILL HELPING TO GENERATE SOME -SHRA AND EVEN SOME ISOLATED TSRA OVER THE LAKE. THIS ACTIVITY IS EXPECTED TO CONTINUE FOR A COUPLE MORE HOURS (THRU ABT 08Z) BEFORE THE FRONT WASHES OUT/PUSHES THROUGH AND COLDER AIR FINALLY MOVES OVER LAKE ERIE TO START SOME LAKE EFFECT. TEMPERATURES WITHIN THE UPSTREAM AIRMASS APPEAR TO BE WARMER THAN ORIGINALLY ANTICIPATED. AIRCRAFT SOUNDINGS INDICATED H85 TEMPS OF +1 TO +3 IN THE BUF AREA AS OF 04Z...AND BY THE LOOKS OF THE IR SAT LOOP...COLDER AIR IS STILL A COUPLE HOURS AWAY FROM ADVECTING INTO THE REGION. THIS WILL DELAY THE ONSET OF LAKE EFFECT...AND WILL ALSO LIKELY RESULT IN MORE LIQUID THAN SNOW FOR THE HIGHER TERRAIN SOUTH OF BUFFALO. HAVE THUS CUT SNOW AMOUNTS WAY BACK FOR THE EARLY MORNING HOURS FOR THE HIGHER TERRAIN. THE LATEST ON STATION 6KM MESOSCALE MODELS SUPPORT THIS WARMER SCENARIO. THEN AS MONDAY UNFOLDS...A 240 FLOW SHOULD ALLOW A FAIRLY WELL ORGANIZED BAND OF LAKE EFFECT RAIN (H85 TEMPS -2 TO -4C) TO HOLD ACROSS THE IAG FRONTIER AND ALONG THE LAKE ERIE SHORE FOR A FEW HOURS. IT WILL LIKELY BE COLD ENOUGH FOR SOME GRAUPEL...AT LEAST ALOFT...SO WILL KEEP THE MENTION OF THUNDER WITHIN THE BAND OF LAKE EFFECT RAIN SHOWERS.MEANWHILE...MUCH LESS ACTIVITY ON A 230 FLOW IS EXPECTED NORTHEAST OF LK ONTARIO. DURING THE AFTERNOON...THE FLOW WILL GRADUALLY BECOME MORE WESTERLY WITH THE LAKE ERIE ACTIVITY BECOMING LESS ORGANIZED WHILE SHIFTING TO THE SOUTH. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... THIS PERIOD WILL FEATURE A NORTHWEST FLOW OF VERY COLD AIR CROSSING THE LAKES...WITH THE ADDITIONAL COMPLICATION OF A COASTAL STORM EXPLODING OVER NEW ENGLAND. WESTERN AREAS WILL JUST DEAL WITH SOME LAKE EFFECT PRECIPITATION.... ESPECIALLY IN UPSLOPE AREAS SOUTHEAST OF THE LAKES. 850 MB TEMPS WILL STILL BE MILD ENOUGH (-4C TO -6C) FOR ANYTHING TO FALL AS MOSTLY RAIN DURING THE DAY TUESDAY AT LOWER ELEVATIONS WITH PERHAPS A SLUSHY INCH OR TWO AT HIGHEST ELEVATIONS OF THE SOUTHERN TIER. THEY DO DROP TO -8C OR LOWER TUES NT AND WED AM...SO ANYTHING WOULD BE SNOW...BUT IT DOES LOOK ONLY SCATTERED ACROSS MOST AREAS WITH PERHAPS AN INCH OR TWO AT HIGHER ELEVATIONS. WILL HAVE TO KEEP AN EYE ON ANY HURON PLUME BRUSHING CHAUT CO WITH MORE ACCUM ON THE RIDGES. RIDGING MOVES IN WEDNESDAY AND DIMINISHES THE ACTIVITY...ENDING IT BY WED EVENING. NOW...MODELS ARE COMING INTO BETTER AGREEMENT WITH DEVELOPING A MAJOR COASTAL STORM OVER NEW ENG TUES MORNING AND LIFTING IT TO QUEBEC BY WED AM. THIS SOLUTION HAS BEEN EVIDENT ON THE ECMWF FOR DAYS...BUT GFS HAS FINALLY COME INTO LINE. THIS STORM WILL DEEPEN RAPIDLY AS IT MOVES NORTH AND PULL COLD AIR INTO IT...WITH LARGE WRAPAROUND AREA OF DEFORMATION ZONE PRECIPITATION...WHICH SHOULD TURN QUICKLY TO SNOW AS IT COOLS...EVEN AT LOWER ELEVATIONS. QUESTION IS HOW FAR WEST THIS SETS UP. GFS AND HPC SHOW A SHARP CUTOFF OF HEAVY SNOW ACROSS ST LAWR AND LEWIS COS...BUT NAM IS FURTHER WEST AND WOULD GIVE BOTH JEFF/LEWIS AND E OSW COUNTY HEAVY SNOW. THERE WILL BE A MAX OF A FOOT FOR MORE SOMEWHERE...LOOKS NOW LIKE THE ADIRONDACKS BUT IT WILL BE CLOSE. WILL AWAIT ONE MORE RUN TO HOIST ANY FLAGS AS THIS SOLUTION IS RATHER SUDDEN...INCLUDED 1-4 INCHES THERE FOR NOW...HIGHEST IN LEWIS CO. IN ANY CASE...AS WINDS BACK TO WNW TUES NT AND WED AM...THERE SHOULD BE A DECENT LK EFFECT SNOW SITUATION SETTING UP FROM WAYNE TO OSW COUNTIES AS AIRMASS WILL BE COLD ENOUGH (-9C 850 MB) EVEN AT LOWER ELEVATIONS. FUTURE SHIFTS WILL NEED TO MONITOR THIS. IT WILL LAST THRU WED AND GRADUALLY TAPER OFF WED NT. && .LONG TERM /THURSDAY THROUGH SUNDAY/... MAJOR PATTERN SHIFT DURING THIS PERIOD AS UPPER LOW LIFTS OUT AND FAST WEST TO SOUTHWEST FLOW OF MUCH MILDER AIR SWEEPS IN ACROSS LOWER LAKES THURS AND FRI. 850 MB TEMPS RISE TO +8C OR SO...RAISED THURS TEMPS A BIT...AND HELD FRI`S IN M-U 50S. SHOULD BE FAIRLY PLEASANT HALLOWEEN EVENING WITH TEMPS NEAR 50 AND DRY CONDITIONS. ANOTHER UPPER TROF SAGS FAR ENOUGH SOUTH TO SEND A WEAKENING COLD FRONT ACROSS THE AREA FRI NT WITH CHC POPS BUT FRONT SHOULD GET FAR ENOUGH SOUTH TO ALLOW FOR SOME CLEARING SATURDAY...HELD CHC POPS SRN TIER ONLY IN MORNING. MUCH COOLER SAT WITH 850 MB TEMPS OF -8C BUT N-NE FLOW AND SHEAR SHOULD NEGATE ANY LK EFFECT. VERY COLD SAT NT BUT SUNDAY LOOKING PLEASANT AT THIS STAGE WITH HIGH CRESTING OVER EASTERN LAKES...SUNSHINE AND TEMPS REBOUNDING TO 50. LONGER RANGE LOOKS MILD WITH ZONAL TO SLIGHT RIDGING MOST OF NEXT WEEK. && .AVIATION /07Z MONDAY THROUGH FRIDAY/... VFR CONDITIONS WILL BE IN PLACE THROUGH THE MUCH OF THE REMAINDER OF THE OVERNIGHT...ALTHOUGH SOME LAKE EFFECT RAIN SHOWERS WILL DEVELOP TOWARDS DAYBREAK OFF OF LAKE ERIE. THIS ACTIVITY COULD HELP TO REDUCE CIGS TO MVFR LEVELS AS RAIN SHOWERS WILL BECOME COMMON FOR KBUF IN PARTICULAR. BEFORE WE GET THE LAKE EFFECT TO DEVELOP THOUGH...A NEARLY STALLED FRONTAL BOUNDARY OVER LAKE ERIE WILL HELP TO GENERATE SOME SHOWERS AND POSSIBLY ANOTHER THUNDERSTORM. LIGHT DETECTION DISPLAYS WERE STILL SHOWING SOME CLOUD TO SFC STRIKES OVER LAKE ERIE AS OF 0550Z. AS MONDAY MORNING UNFOLDS...VFR CONDITIONS WILL REMAIN IN PLACE FOR THE MAJORITY OF WRN AND NORTH CENTRAL NEW YORK. THE EXCEPTION WILL AGAIN BE FOUND IN THE VCNTY OF KBUF WHERE CIGS/VSBYS WILL RANGE FROM MVFR TO OCCASIONALLY IFR IN STEADY LAKE RAIN SHOWERS. THESE SHOWERS MAY BE ACCOMPANIED BY AN OCCASIONAL RUMBLE OF THUNDER. AS WINDS VEER MORE TO THE WEST DURING THE COURSE OF THE DAY...THE LAKE SHOWERS/LOWER CIGS WILL SETTLE TO THE SOUTH TOWARDS KJHW. THIS WILL LEAD TO MVFR TO OCCASIONALLY IFR CIGS FOR KJHW FOR THE AFTERNOON INTO MONDAY NIGHT. FOR MONDAY NIGHT...VFR CONDITIONS WILL PREVAIL OVER THE REGION. A CHILLY NORTH TO NORTHWEST FLOW WILL KEEP ANY LAKE INDUCED MVFR CIGS/VSBYS CONFINED TO SITES SUCH AS KJHW...ALTHOUGH MVFR CONDITIONS WILL NOT BE OUT OF THE QUESTION FOR KROC. OUTLOOK... TUESDAY...MVFR/AREAS OF IFR IN LAKE EFFECT RAIN AND SNOW SHOWERS. WEDNESDAY...MVFR/AREAS IFR IN LAKE EFFECT SNOW SHOWERS SE OF THE LAKES. THURSDAY...VFR. FRIDAY...OCCASIONAL MVFR IN SHOWERS. && .MARINE... NORTHWEST WINDS WILL INCREASE AGAIN DURING TUESDAY AND MAY REACH GALE FORCE ON MUCH OF LAKE ONTARIO IN RESPONSE TO THE STRONG SURFACE LOW LIFTING NORTH ACROSS NEW ENGLAND INTO QUEBEC. THIS LOW WILL TIGHTEN THE PRESSURE GRADIENT ACROSS THE LOWER GREAT LAKES...AND DRAW DOWN MUCH COLDER AIR WHICH WILL STEEPEN THE LOW LEVEL LAPSE RATES OVER THE WARM LAKE WATERS AND ALLOW FOR EFFICIENT MOMENTUM TRANSFER OF HIGHER WINDS DOWN TO THE SURFACE. WINDS ARE EXPECTED TO DIMINISH THURSDAY AS SURFACE HIGH PRESSURE BUILDS INTO THE REGION. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LEZ040- 041. SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS AFTERNOON FOR LEZ020. SMALL CRAFT ADVISORY UNTIL 6 AM EDT TUESDAY FOR LOZ042>044. SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR LOZ045. && $$ SYNOPSIS...SFM NEAR TERM...RSH SHORT TERM...SFM LONG TERM...SFM AVIATION...RSH MARINE...RSH/SFM
AREA FORECAST DISCUSSION
NWS BUFFALO NY
209 AM EDT MON OCT 27 2008 .SYNOPSIS... A STRONG COLD FRONT WILL CROSS THE REGION THIS EVENING WITH WINDY CONDITIONS AND A CHANCE OF RAIN SHOWERS. THIS FRONT WILL USHER IN THE COLDEST AIR OF THE SEASON AND SET THE STAGE FOR AN EXTENDED PERIOD OF LAKE EFFECT PRECIPITATION. INITIALLY A RAIN AND WET SNOW MIX IS EXPECTED DOWNWIND OF THE LAKES LATE TONIGHT THROUGH TUESDAY...THEN THE AIR IS EXPECTED TO BECOME COLD ENOUGH TO SUPPORT ALL SNOW SOUTHEAST OF THE LAKES TUESDAY NIGHT INTO WEDNESDAY WITH THE POTENTIAL FOR ACCUMULATING LAKE SNOWS IN THE SNOWBELTS. && .NEAR TERM /THROUGH TODAY/... A NEARLY STALLED FRONTAL BOUNDARY OVER LAKE ERIE AT 06Z WAS STILL HELPING TO GENERATE SOME -SHRA AND EVEN SOME ISOLATED TSRA OVER THE LAKE. THIS ACTIVITY IS EXPECETD TO CONTINUE FOR A COUPLE MORE HOURS (THRU ABT 08Z) BEFORE THE FRONT WASHESOUT/PUSHES THROUGH AND COLDER AIR FINALLY MOVES OVER LAKE ERIE TO START SOME LAKE EFFECT. TEMPERATURES WITHIN THE UPSTREAM AIRMASS APPEAR TO BE WARMER THAN ORIGINALLY ANTICIPATED. AIRCRAFT SOUNDINGS INDICATED H85 TEMPS OF +1 TO +3 IN THE BUF AREA AS OF 04Z...AND BY THE LOOKS OF THE IR SAT LOOP...COLDER AIR IS STILL A COUPLE HOURS AWAY FROM ADVECTING INTO THE REGION. THIS WILL DELAY THE ONSET OF LAKE EFFECT...AND WILL ALSO LIKELY RESULT IN MORE LIQUID THAN SNOW FOR THE HIGHER TERRAIN SOUTH OF BUFFALO. HAVE THUS CUT SNOW AMOUNTS WAY BACK FOR THE EARLY MORNING HOURS FOR THE HIGHER TERRAIN. THE LATEST ON STATION 6KM MESOSCALE MODELS SUPPORT THIS WARMER SCENARIO. THEN AS MONDAY UNFOLDS...A 240 FLOW SHOULD ALLOW A FAIRLY WELL ORGANIZED BAND OF LAKE EFFECT RAIN (H85 TEMPS -2 TO -4C) TO HOLD ACROSS THE IAG FRONTIER AND ALONG THE LAKE ERIE SHORE FOR A FEW HOURS. IT WILL LIKELY BE COLD ENOUGH FOR SOME GRAUPEL...AT LEAST ALOFT...SO WILL KEEP THE MENTION OF THUNDER WITHIN THE BAND OF LAKE EFFECT RAIN SHOWERS.MEANWHILE...MUCH LESS ACTIVITY ON A 230 FLOW IS EXPECTED NORTHEAST OF LK ONTARIO. DURING THE AFTERNOON...THE FLOW WILL GRADUALLY BECOME MORE WESTERLY WITH THE LAKE ERIE ACTIVITY BECOMING LESS ORGANIZED WHILE SHIFTING TO THE SOUTH. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... OUR ATTENTION IN THE SHORT TERM WILL BE FOCUSED ON THE MESOSCALE WITH A LONG LASTING EARLY SEASON LAKE EFFECT EVENT ONGOING THROUGHOUT THE PERIOD. FIRST SOME SYNOPTICS...A DEEP LONGWAVE TROUGH WILL BE WELL ESTABLISHED OVER THE GREAT LAKES AND NEW ENGLAND THROUGH THE PERIOD. A GENERAL CYCLONIC NORTHWEST FLOW WILL CONTINUE THROUGH THE PERIOD WITH NUMEROUS DIFFICULT TO TIME SHORTWAVES. MODELS ARE STILL NOT IN GOOD AGREEMENT WITH RESPECT TO THE DETAILS OF COASTAL CYCLOGENESIS ALONG THE NORTHERN NEW ENGLAND COAST TUESDAY AND TUESDAY NIGHT. THIS SYSTEM WILL STAY WELL TO OUR EAST...BUT THE FLOW AROUND THE DEVELOPING CIRCULATION MAY HAVE IMPORTANT IMPLICATIONS ON OUR LAKE EFFECT REGIME. THE CYCLONIC FLOW AND PASSAGE OF VARIOUS SHORTWAVES WILL KEEP SCATTERED RAIN AND SNOW SHOWERS GOING THROUGH MUCH OF THE PERIOD AWAY FROM LAKE EFFECT AREAS. NOW FOR THE LAKE EFFECT... OFF LAKE ERIE...SECONDARY COLD FRONT AND MID LEVEL SHORTWAVE WILL BE IN THE PROCESS OF DROPPING SOUTHEAST ACROSS WESTERN NY MONDAY EVENING. EXPECT THIS TO ENHANCE THE LAKE ERIE BAND AND DRIVE IT QUICKLY SOUTH THROUGH SKI COUNTRY AND INTO THE SOUTHERN TIER DURING THE EVENING. PTYPE SHOULD BE ALL RAIN INITIALLY WITH 850MB TEMPS ONLY -2C TO -3C. THIS BAND MAY BREAK APART DUE TO THE QUICK WIND SHIFT AND SUBSEQUENT INCREASE IN SHEAR. LATER MONDAY NIGHT RIGHT THROUGH TUESDAY NIGHT EXPECT MULTIPLE BANDS TO DEVELOP ACROSS THE WESTERN SOUTHERN TIER ON NW FLOW AND FOCUS ON THE CHAUTAUQUA RIDGE. 850MB TEMPS SLOWLY DROP LATER MONDAY NIGHT THROUGH TUESDAY. THIS SHOULD SUPPORT A STEADY LOWERING OF SNOW LEVELS WITH SNOW BEGINNING TO MIX IN BY 06Z TUE ABOVE 1800 FEET...THEN AT LOWER ELEVATIONS BY TUESDAY MORNING AS 850MB TEMPS DROP TO -5C. ON TUESDAY EXPECT A RAIN/SNOW MIX ACROSS LOWER ELEVATIONS...AND PROBABLY ALL SNOW ABOVE ABOUT 1200 FEET OR SO AS 850MB TEMPS DROP TO AROUND -7C BY AFTERNOON. TUESDAY NIGHT THROUGH WEDNESDAY FORECAST PROFILES ARE PLENTY COLD ENOUGH FOR ALL SNOW. AS FAR AS AMOUNTS GO...THE LONG DURATION OF THE EVENT SUGGESTS SIGNIFICANT ACCUMULATIONS ARE POSSIBLE ALONG THE CHAUTAUQUA RIDGE. BOUNDARY LAYER WINDS WILL BE NEARLY PERPENDICULAR TO THE RIDGE LINE CREATING EFFICIENT UPSLOPE FLOW. THE MAJOR WILDCARD IN THIS SETUP IS THE EVENTUAL PLACEMENT OF THE UPSTREAM CONNECTION TO LAKE HURON... AND THIS TYPE OF DETAIL CANNOT BE FORECAST AT THIS TIME RANGE. IN THESE TYPES OF EVENTS...THE HEAVIEST SNOWS TEND TO CONCENTRATE IN NARROW AREA ALONG THE LEADING EDGE OF THE HIGHER TERRAIN...IN PLACES LIKE SHERMAN...MAYVILLE... SOUTH DAYTON...AND PERRYSBURG. ALONG THE LAKESHORE THERE WILL PROBABLY BE VERY LITTLE...WITH LOWERING AMOUNTS AS YOU MOVE FURTHER INLAND AWAY FROM THE RIDGE LINE. GIVEN THE FORECAST THERMAL PROFILES AND LAKE INSTABILITY...THE BEST TIME WINDOW FOR ACCUMULATING SNOWS APPEARS TO BE FROM LATE TUESDAY AFTERNOON THROUGH WEDNESDAY MORNING. STILL TOO EARLY FOR A WATCH... BUT WILL CONTINUE TO MONITOR. OFF LAKE ONTARIO...EXPECT A SIMILAR SCENARIO WITH AN ENHANCED FRONTAL BAND UP NEAR WATERTOWN EARLY MONDAY EVENING MOVING QUICKLY SOUTH ACROSS THE TUG HILL AND SETTLING ALONG THE SOUTHEAST SHORE LATER IN THE EVENING. TEMPERATURE PROFILES SUGGEST MAINLY RAIN ACROSS LOWER ELEVATIONS MONDAY EVENING...WITH PERHAPS AN INCH OR TWO OF SLUSH ON THE TUG HILL. DURING THE DAY TUESDAY FLOW WILL BE NORTHWEST...AND PROBABLY TOO MUCH NORTHERLY COMPONENT TO STILL SUPPORT A GOOD SINGLE BAND. EXPECT WIDESPREAD MULTIPLE BANDS FROM EASTERN NIAGARA THROUGH OSWEGO COUNTIES...EXTENDING WELL INLAND INTO THE FINGER LAKES. BOUNDARY LAYER TEMPS STILL LOOK TOO WARM TO SUPPORT MUCH ACCUMULATION IN THESE LOWER ELEVATION AREAS...BUT WILL NEED TO WATCH THE BRISTOL HILLS CLOSELY IN ONTARIO COUNTY. TUESDAY NIGHT INTO WEDNESDAY A SURFACE LOW DEVELOPING JUST EAST OF MAINE MAY TEND TO BACK THE WINDS A LITTLE OVER LAKE ONTARIO. THIS MAY SETUP A MORE FAVORABLE SCENARIO FOR A SINGLE PLUME OF LAKE EFFECT COMING INTO WAYNE/NORTHERN CAYUGA/OSWEGO COUNTIES. 850MB TEMPS COLD ENOUGH TO SUPPORT ALL SNOW TUESDAY NIGHT THROUGH WEDNESDAY. AGAIN...AT THIS TIME RANGE THE SPECIFICS ON THE EXACT PLACEMENT AND INTENSITY OF THIS BAND ARE VERY UNCERTAIN...HOWEVER THE POTENTIAL CERTAINLY EXISTS FOR ACCUMULATING LAKE EFFECT SNOW SOUTHEAST OF LAKE ONTARIO DURING THIS TIME PERIOD. STAY TUNED... && .LONG TERM /THURSDAY THROUGH SUNDAY/... EXTENDED MODEL GUIDANCE IS BEGINNING TO COME BACK INTO BETTER AGREEMENT AGAIN WITH RESPECT TO THE LONGWAVE PATTERN EVOLUTION WITH A GENERAL TREND TOWARDS DE-AMPLIFICATION AND A MORE ZONAL FLOW ACROSS THE NOAM SECTOR BY DAY 7. FULL DISK SATELLITE IMAGERY THIS AFTERNOON SHOWING A PARADE OF STRONG PACIFIC SHORTWAVES OVER THE CENTRAL AND WESTERN PACIFIC. THESE SHORTWAVES WILL MOVE ONSHORE IN THE PACIFIC NORTHWEST AND BRITISH COLUMBIA AND EFFECTIVELY KNOCK DOWN THE WESTERN RIDGE WITH CONCURRENT DOWNSTREAM DE-AMPLIFICATION AND HEIGHT RISES OVER THE EASTERN CONUS. LOOKING AT THE DETAILS...THURSDAY AND FRIDAY HEIGHTS WILL RISE SIGNIFICANTLY AS THE NORTHEAST USA/SOUTHEAST CANADA TROUGH LIFTS RAPIDLY INTO ATLANTIC CANADA IN RESPONSE TO AN UPSTREAM KICKER DIGGING THROUGH THE CANADIAN PRAIRIES. AT THE SAME TIME A SURFACE HIGH WILL BUILD INTO THE MID ATLANTIC...WITH INCREASING SOUTHERLY RETURN FLOW ALLOWING 850MB TEMPS TO SOAR TO +8C OR BETTER THURSDAY AND FRIDAY. THIS WILL BRING TEMPERATURES RAPIDLY BACK TO SEASONAL AVERAGES OR EVEN A LITTLE ABOVE BY THE END OF THE WEEK. LATEST 00Z/26 MODEL GUIDANCE IS COMING INTO BETTER AGREEMENT FOR NEXT WEEKEND. BOTH THE GFS AND ECMWF DIG A RATHER POTENT SHORTWAVE INTO SOUTHEAST CANADA FRIDAY NIGHT INTO SATURDAY. THIS WILL DRAG A SHALLOW SURFACE COLD FRONT SOUTH ACROSS THE LOWER LAKES AND BRING A QUICK SHOT OF COLDER AIR TO THE REGION. THE SURFACE FRONT WILL BE SHALLOW AND HAVE LITTLE MOISTURE OR UPPER LEVEL FORCING FOR ASCENT ASSOCIATED WITH IT. FOR NOW WILL JUST COVER THE FROPA WITH LOW CHANCE POPS FRI NIGHT INTO SATURDAY. TEMPERATURES WILL DROP BACK TO A LITTLE BELOW AVERAGE FOR NEXT WEEKEND IF THE CURRENT MODEL FORECASTS VERIFY. LOOKING A LITTLE FURTHER AHEAD...THE GEFS ENSEMBLE MEAN AND THE LOW RESOLUTION BAROTROPIC DAVA MODEL ARE IN GOOD AGREEMENT IN BUILDING AN AREA OF WELL ABOVE AVERAGE HEIGHTS CENTERED ON THE GREAT LAKES IN THE 8-14 DAY RANGE. BASED ON THIS UPPER AIR PATTERN...KLEIN AND NEURAL NET TOOLS FROM CPC SUPPORT A HIGH PROBABILITY OF ABOVE NORMAL TEMPERATURES FOR WEEK 2 OF THE FORECAST. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... VFR CONDITIONS WILL BE IN PLACE THROUGH THE MUCH OF THE REMAINDER OF THE OVERNIGHT...ALTHOUGH SOME LAKE EFFECT RAIN SHOWERS WILL DEVELOP TOWARDS DAYBREAK OFF OF LAKE ERIE. THIS ACTIVITY COULD HELP TO REDUCE CIGS TO MVFR LEVELS AS RAIN SHOWERS WILL BECOME COMMON FOR KBUF IN PARTICULAR. BEFORE WE GET THE LAKE EFFECT TO DEVELOP THOUGH...A NEARLY STALLED FRONTAL BOUNDARY OVER LAKE ERIE WILL HELP TO GENERATE SOME SHOWERS AND POSSIBLY ANOTHER THUDNERSTORM. LIGHT DETECTION DISPLAYS WERE STILL SHOWING SOME CLOUD TO SFC STRIKES OVER LAKE ERIE AS OF 0550Z. AS MONDAY MORNING UNFOLDS...VFR CONDITIONS WILL REMAIN IN PLACE FOR THE MAJORITY OF WRN AND NORTH CENTRAL NEW YORK. THE EXCEPTION WILL AGAIN BE FOUND IN THE VCNTY OF KBUF WHERE CIGS/VSBYS WILL RANGE FROM MVFR TO OCCASIONALLY IFR IN STEADY LAKE RAIN SHOWERS. THESE SHOWERS MAY BE ACCOMPANIED BY AN OCCASIONAL RUMBLE OF THUDNER. AS WINDS VEER MORE TO THE WEST DURING THE COURSE OF THE DAY...THE LAKE SHOWERS/LOWER CIGS WILL SETTLE TO THE SOUTH TOWARDS KJHW. THIS WILL LEAD TO MVFR TO OCCASIONALLY IFR CIGS FOR KJHW FOR THE AFTERNOON INTO MONDAY NIGHT. FOR MONDAY NIGHT...VFR CONDITIONS WILL PREVAIL OVER THE REGION. A CHILLY NORTH TO NORTHWEST FLOW WILL KEEP ANY LAKE INDUCED MVFR CIGS/VSBYS CONFINED TO SITES SUCH AS KJHW...ALTHOUGH MVFR CONDITIONS WILL NOT BE OUT OF THE QUESTION FOR KROC. OUTLOOK... TUESDAY...MVFR/AREAS OF IFR IN LAKE EFFECT RAIN AND SNOW SHOWERS. WEDNESDAY...MVFR/AREAS IFR IN LAKE EFFECT SNOW SHOWERS SE OF THE LAKES. THURSDAY...VFR. FRIDAY...OCCASIONAL MVFR IN SHOWERS. && .MARINE... IN COORDINATION WITH CLE...HAVE DROPPED THE GALE WARNINGS FOR LAKE ERIE AND LAKE ONTARIO WITH THE 10 PM ISSUANCE OF THE MARINE FORECASTS...AS WINDS HAVE GENERALLY BEEN ON THE WANE THIS EVENING... WITH THE EXCEPTION OF SOME OCCASIONALLY STRONGER CONVECTIVELY- INDUCED WINDS ON BOTH LAKES. GENERAL SOUTHWEST WINDS WILL CONTINUE TO SUBSIDE TONIGHT...BUT THEY WILL REMAIN PLENTY STRONG ENOUGH TO WARRANT CONTINUED SMALL CRAFT ADVISORIES THROUGH AT LEAST MONDAY. WINDS FINALLY SHIFT TO NORTHWEST LATE MONDAY AND CONTINUE INTO TUESDAY...WITH SMALL CRAFT ADVISORIES LIKELY NEEDED ALONG THE SOUTH SHORES OF BOTH LAKES THROUGH TUESDAY WITH COLD AIR BRINGING WINDS ALOFT DOWN TO THE SURFACE. NORTHWEST WINDS WILL INCREASE AGAIN TUESDAY NIGHT INTO WEDNESDAY WITH A LIKELIHOOD OF GALE FORCE WINDS...ESPECIALLY ON LAKE ONTARIO. THIS WILL BE IN RESPONSE TO A STRONG SURFACE LOW DEVELOPING ALONG THE NORTHERN NEW ENGLAND COAST AND TRACKING INTO EASTERN QUEBEC. THIS LOW WILL TIGHTEN THE PRESSURE GRADIENT ACROSS THE LOWER GREAT LAKES...AND DRAW DOWN MUCH COLDER AIR WHICH WILL STEEPEN THE LOW LEVEL LAPSE RATES OVER THE WARM LAKE WATERS AND ALLOW FOR EFFICIENT MOMENTUM TRANSFER OF HIGHER WINDS DOWN TO THE SURFACE. WINDS ARE EXPECTED TO DIMINISH THURSDAY AS SURFACE HIGH PRESSURE BUILDS INTO THE REGION. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LEZ040- 041. SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS AFTERNOON FOR LEZ020. SMALL CRAFT ADVISORY UNTIL 6 AM EDT TUESDAY FOR LOZ042>044. SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR LOZ045. && $$ SYNOPSIS...HITCHCOCK NEAR TERM...RSH SHORT TERM...HITCHCOCK LONG TERM...HITCHCOCK AVIATION...RSH MARINE...APB/HITCHCOCK
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
440 AM PDT MON OCT 27 2008 NEW AVIATION DISCUSSION .SHORT TERM... MARINE LAYER NOT BEHAVING VERY WELL TONIGHT AS GRADIENTS ARE TRENDING A LITTLE MORE OFFSHORE THAN THEY WERE LAST NIGHT. THE BULK OF THE DENSE FOG IS OVER THE CENTRAL COAST WHERE A DENSE FOG ADVISORY IS IN EFFECT THROUGH 8 AM. ACARS SOUNDING OUT OF KLAX SHOWS THE MARINE AT 500 FEET OR BELOW. BUT IT IS 78 DEGREES AT 1000 FEET WHICH WILL MAKE FOR ANOTHER WARM DAY IN THE VLYS AND COASTAL INLAND AREAS. THE COASTAL AREAS WILL REMAIN COOL. SOME HIGH CLOUDS ROTATING AROUND AN UPPER LOW 900 NM WEST OF SFO WILL CREATE PARTLY CLOUDY SKIES FOR SLO AND SBA COUNTIES. DUE TO THE WARM DRY AIR ABOVE THE INVERSION A RED FLAG WARNING WILL CONTINUE TODAY FOR EXTENDED VERY LOW CONDITIONS. TUESDAY THE RIDGE BREAKS DOWN A LITTLE AS A TROF RIDES UP INTO NORTHERN CA. THIS SHOULD LIFT THE MARINE LAYER ENOUGH TO GREATLY REDUCE OR ELIMINATE THE DENSE FOG. HARD TO FIGURE WHY BUT MOS GUIDANCE FORECASTS A 4 TO 5 DEGREE WARM UP OVER MOST AREAS DUE TO A SPIKE IN 950 AND BL TEMPS. THINK THIS IS A LITTLE OVERDONE ESP WITH THE GREATER MARINE LAYER AND ONSHORE FLOW. WEDNESDAY SHOULD BE MUCH LIKE TUESDAY WITH SUNNY SKIES PREVAILING AFTER A ROUND OF MORNING LOW CLOUDS AND FOG. THE SYNOPTIC PATTERN IS A LITTLE MORE STATIC WITH A RIDGE SETTING UP OVER AC AND A DIGGING TROF SETTING UP OVER THE EAST PAC. .LONG TERM... INTERESTING TIMES IN THE EXTENDED FORECAST BUT SOMEWHAT CHALLENGING TO FIGURE OUT HOW INTERESTING. THE GFS AND EC AGREE FAIRLY WELL EXCEPT IN THE CRITICAL WEEKEND PERIOD WHERE EC IS QUICKER THAN THE SLOWER EC. ALL GFS ENSEMBLES TEND TOWARD THE OPERATIONAL GFS. BUT 18Z AND 00Z GFS HAVE TRENDED MUCH WETTER. CONFIDENCE IN THURSDAY AND FRIDAY FORECAST LOOKS GOOD. WITH RIDGE SLOWLY MOVING TO THE EAST AND THE TROF SLOWLY APPROACHING THE COAST THE DAYS WILL SLOWLY COOL. THE MARINE LAYER WILL EXPAND ON THURSDAY. SKIES WILL TURN PARTLY CLOUDY THU AFTERNOON AS MID AND HIGH LEVEL MOISTURE EMBEDDED IN THE SW FLOW AHEAD OF THE TROF STREAMS OVER THE AREA. THE MARINE LAYER MAY WELL BE DISRUPTED BY THE UPPER LEVEL CLOUDS FRIDAY AND WITH ALL THE CLOUDS WORDED THE FORECAST AS PARTLY TO MOSTLY CLOUDY WHICH WILL LIKELY WILL BEST DESCRIBE THE DAY. SATURDAY AND SUNDAY WILL BE COOLER AS THE LOW APPROACHES. AS MENTIONED ABOVE THE GFS IS SLOWER AND FAIRLY WET AND THE EC IS FASTER AND DRIER. IT LOOKS MORE AND MORE LIKELY THAT THE CENTRAL COAST WILL SEE SOME RAIN THIS WEEKEND BUT THE TIMING UNCERTAINTIES DO NOT ALLOW ANY ONE 6 OR 12 HOUR TIME BLOCK TO HOLD HIGHER THAN SLGT CHC POPS. SOUTH OF POINT CONCEPTION IF THE GFS FINDS ITS SUBTROPICAL MOISTURE PLUME...AS THE GFS IS ADVERTISING...THERE WILL BE RAIN AND MAYBE A DECENT AMOUNT. THE GFS IS SLOWER AND KEEPS ALL THE PRECIP OUT OF THE AREA UNTIL SUNDAY. IT WILL BE INTERESTING TO WATCH THIS SYSTEM EVOLVE. && .AVIATION...27/1140Z. EXTREMELY LOW CONFIDENCE IN THE AVIATION FORECAST THIS MORNING. CUTOFF LOW JUST OFF THE CENTRAL COAST IS WREAKING HAVOC ON THE CONFIGURATION OF THE MARINE CLOUD AND FOG COVERAGE. THE ONE ASPECT OF THE FORECAST THAT DOES HAVE SOME CONFIDENCE IS THE EXPECTATION OF DENSE FOG CONDITIONS AT MANY TAF LOCATIONS THIS MORNING. THE MOST DIFFICULT PARAMETER IS SPECIFYING THE EXACT TIMING OF DENSE FOG CONDITIONS SINCE THE FOG AND LOW CLOUDS IS CONSTANTLY IN MOTION AND SUBJECT TO CHANGE. KLAX...A 60 PERCENT CHANCE OF DENSE FOG MORE THAN HALF OF THE TIME THROUGH 16Z. OCCASIONAL TRANSITORY PERIODS OF CLEARING ARE ALSO LIKELY. CLEAR SKIES AND GOOD VISIBILITY EXPECTED AFTER 16Z THROUGH THIS EVENING BEFORE THE FOG RETURNS AGAIN OVERNIGHT MONDAY NIGHT. KBUR...HIGH CONFIDENCE IN CLEAR SKIES THROUGH THIS EVENING. && .LOX WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING (SEE LAXRFWLOX). DENSE FOG ADVISORY (SEE LAXNPWLOX). && $$ PUBLIC...RORKE AVIATION...SWEET WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
722 AM EDT MON OCT 27 2008 .SYNOPSIS... A SERIES OF WEAK DISTURBANCES EMBEDDED IN NORTHWEST FLOW ALOFT WILL BRING SEVERAL DAYS OF UNSEASONABLY COOL TEMPERATURES AND THE SEASON`S FIRST LAKE EFFECT SNOWS. FAIR WEATHER AND MODERATING TEMPERATURES WILL RETURN LATER IN THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... SHOWERS IN NRN AND WRN MTS WILL CONTINUE TO DWINDLE AS THEY TRY TO MOVE TO THE EAST. THE COLD FRONTAL TROF LOOKS TO BE OVER THE SUSQ VALLEY ACCORDING TO THE PRESSURE FIELD...BUT THE COLD AIR IS JUST STARTING TO MOVE INTO EASTER OHIO ACCORDING TO THE SFC OBS. WATER VAPOR SHOWS A POTENT SHORT WAVE MOVING THRU OHIO...WHICH PROMISES TO HELP FIRE UP THE LAKE EFFECT MACHINE OVER THE NEXT COUPLE OF DAYS AS INCREASINGLY CHILLY AIR POURS INTO THE REGION. FOR TODAY CLOUDS WILL BE ON THE INCREASE AS THE CYCLONIC FLOW...COLD ADVECTION AND LOW LEVEL MOISTURE MAKE THEIR PRESENCE FELT. MODELS AGREE THE BEST CHANCE OF PRECIP TODAY WILL BE OROGRAPHIC AND LAKE ENHANCED...MEANING WESTERN AND NORTHER HIGH TERRAIN WILL STAND THE BEST CHANCE OF SEEING SHOWERS. HAVE ALSO INSERTED WORDING FOR AN ISOLATED THUNDERSTORM TODAY AS THE VERY COLD AIR ALOFT ACCOMPANYING THE SHORTWAVE WILL WORK TO SHARPLY DECEASE STABILITY. PROGGED MID LEVEL LAPSE RATES EXCEED 7C/KM BY AFTERNOON...WITH LI`S APPROACHING ZERO AND T-TOTALS NEARING 60. WE WILL BE FAIRLY DRY OVERALL...BUT WITH SO MUCH COLD AIR ALOFT POURING IN...SOME OF THE SHOWERS WILL HAVE THE POTENTIAL MAKE FOR A FEW RUMBLES OF THUNDER AND PERHAPS SOME SMALL HAIL/GRAUPEL. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... SIGNIFICANT DIFFERENCES ARISE EARLY ON IN THE MODEL GUIDANCE WITH THE NAM WANTING TO BRUSH MY FAR EASTERN COUNTIES WITH SOME SIG PRECIP ASSOCIATED WITH EVENTUAL OFFSHORE DEVELOPMENTS ASSOCIATED WITH OUR DEEPENING UPPER AIR LOW/TROF. WHILE MOST GUIDANCE AGREES WE SEE SOME SORT OF DEVELOPMENT ALONG OR JUST OFF THE EASTERN SEABOARD...THE 00Z NAM IS THE OUTLIER BRINGING SO MUCH PRECIP SO FAR WEST NEAR MY FCST AREA. 00Z GEFS AND 21Z SREF SUGGEST LOW TO NO POPS IN THE EAST WHILE THE OPERATIONAL MODELS KEEP THE BEST LOW LEVEL MOISTURE FLUX AND PWAT ANOMALIES REMAIN WELL OFFSHORE. DID COMPROMISE A TAD ON THE FAR EASTERN CHANCES FOR RAIN TUESDAY...TO BETTER BLEND WITH EASTERN NEIGHBORS...BUT BELIEVE THE CHANCES FOR PRECIP WILL BE VERY LOW OVERALL. THE MAIN ACTION SHOULD STAY IN THE WEST AND NW WHERE PREVIOUSLY MENTIONED OROGRAPHIC AND LAKE EFFECT FORCES MANAGE TO BRING THE HIGHEST CHANCES FOR PRECIP. THINK THE SEASON`S FIRST ACCUMULATING SNOWS WILL BE SEEN IN THE USUAL SNOW BELT AREAS...BUT WITH MARGINAL SURFACE TEMPS AND RELATIVELY SHORT OVER-LAKE WIND FETCHES...HAVE KEPT THE MENTION OF ACCUMULATIONS ON THE LIGHT SIDE. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... WE MAY SEE A WINDOW OF OPPORTUNITY FOR SLIGHTLY HEAVIER LAKE EFFECT TUESDAY NIGHT INTO WED AS GUIDANCE SUGGESTS A BETTER OVER- LAKE FETCH AND A POSSIBLE LAKE HURON CONNECTION. STILL TOO EARLY TO ZERO IN ON WHAT WOULD BE A MESO SCALE FEATURE...JUST SOMETHING TO CONSIDER FOR THE MEDIUM RANGE. BIGGER PATTERN WILL KEEP US COLDER THAN NORMAL FOR THE NEXT SEVERAL DAYS...BEFORE SOME MODERATING TEMPS MAKE A RETURN LATER IN THE WEEK. OTHER THAN WRESTLING WITH LAKE/OROGRAPHIC SHOWERS...PRECIP WILL NOT BE A BIG CONCERN. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... FIRST BAND OF SHOWERS MADE IT AS FAR EAST AS THE OFFICE OVERNIGHT. A FEW SPOTS HAD MVFR CONDITIONS FOR A BRIEF TIME. MOST OF TODAY WILL BE VFR...BEFORE SECONDARY FRONT MOVES IN LATE. HAD SOME THUNDERSTORMS OVER LAKE ERIE EARLIER...ONLY THE SECOND TIME I HAVE SEEN LAKE EFFECT STORMS THAT FAR FROM THE RADAR SINCE THE OFFICE WAS OPEN. LAST TIME WAS 2 YEARS AGO. WHILE WINDS ALOFT ARE ON THE STRONG SIDE...WINDS AT LOW LEVELS WILL NOT REALLY PICK UP MUCH TODAY. WINDS INCREASE AFTER 06Z TONIGHT... ONCE THE UPPER LEVEL TROUGH GOES BY. WITH SUCH STRONG WINDS... WOULD NOT BE SURPRISE TO SEE REPORTS OF SEVERE TURB. FROM THE LARGER AIRCRAFT TODAY. CURRENT AREA OF SHOWERS FALLING APART...AS WINDS BACK MORE... AND FRONT STALLS ACROSS THE MTNS. LATE TONIGHT...COASTAL DEVELOPS AND WINDS PICK UP...AND CONDITIONS BECOME MORE MVFR WITH SOME IFR CONDITIONS. MOST SPOTS WILL HAVE RAIN FOR PCPN TYPE...BUT SOME SNOW WILL BE POSSIBLE AFTER 08Z. SOME LAKE EFFECT RAIN AND SNOW SHOWERS ON TUE...BUT WILL BE LIMITED...AS TEMPS WILL BE MARGINAL FOR SNOW...AND WINDS WILL FAVOR MULTIPLE BANDS. INCREASING CONCERN OVER COASTAL LOW...SYSTEM LIKELY TO DEEPEN FAST...AS JET ROUNDS BASE OF TROUGH...AND WINDS AT 500 MB MAY EXCEED 100 KNOTS. SHOULD SYSTEM CUT OFF MUCH FURTHER TO THE SOUTH AND WEST...HEAVY WET SNOW MAY BECOME A PROBLEM FOR AREAS JUST TO THE EAST OF IPT. OCT 1987 AND OCT 1993 HAD A SIMILAR EVENTS. IMPROVING CONDITIONS LATER WED INTO FRIDAY...AS A LARGE SCALE WARM UP OCCURS. SHOULD BE VFR CONDITIONS. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LACORTE NEAR TERM...LACORTE SHORT TERM...LACORTE LONG TERM...LACORTE AVIATION...MARTIN