454
FXUS61 KBUF 210752
AFDBUF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
252 AM EST SAT NOV 21 2009
SYNOPSIS
HIGH PRESSURE WILL BUILD OVER THE REGION THIS WEEKEND BEFORE
SHIFTING OFF THE NEW ENGLAND COAST BY EARLY NEXT WEEK. WHILE HIGH
PRESSURE WILL BE IN PLACE TODAY...RESIDUAL CLOUD COVER WILL REMAIN
BEFORE GIVING WAY TO SUNSHINE FOR SUNDAY AND MONDAY. A STORM SYSTEM
WILL APPROACH FROM THE MIDWEST ON WEDNESDAY AND BRING THE NEXT
CHANCE OF RAIN WITH UNSETTLED CONDITIONS LASTING THROUGH THE END OF
THE WEEK. TEMPERATURES WILL CONTINUE TO REMAIN ABOVE AVERAGE THROUGH
THE FIRST HALF OF NEXT WEEK BEFORE A COOLING TREND BY THE
THANKSGIVING HOLIDAY.
NEAR TERM /THROUGH TONIGHT/
WEAK UPPER LEVEL TROUGH WILL LINGER ACROSS THE EASTERN GREAT LAKES
REGION TODAY. SURFACE RIDGE EXTENDING THROUGH THE OHIO VALLEY TO THE
MID ATLANTIC COAST WILL GRADUALLY BUILD NORTHWARD THROUGH TONIGHT.
WATER VAPOR LOOP EARLY THIS MORNING SHOWING A MID LEVEL WAVE
PUSHING THROUGH THE SOUTHERN GREAT LAKES. LIFT FROM THIS WAVE IS
NOT IMPRESSIVE...BUT AN AREA OF MID LEVEL MOISTURE ASSOCIATED WITH
IT WILL SPREAD OVER THE AREA AS THE WAVE TRACKS EASTWARD TODAY.
MODEL SOUNDINGS ALSO SHOWING AMPLE LOW LEVEL MOISTURE LINGERING
OVER THE REGION...RESULTING IN THE DEVELOPMENT OF LOW STRATUS AND
FOG THROUGH THIS MORNING. WEAK FLOW WILL LIMIT MIXING TODAY AND
THE LOW AND MID LEVEL MOISTURE WILL RESULT IN PLENTY OF CLOUD
COVER THROUGH EARLY TONIGHT. THE CLOUD COVER WILL HOLD
TEMPERATURES TODAY IN THE UPPER 40S TO LOWER 50S.
MODELS CONTINUING TO INSIST THAT IMPROVING CONDITIONS WILL TAKE
PLACE TONIGHT. MID LEVEL RIDGING ADVANCING INTO THE REGION
TONIGHT BEHIND THE UPPER WAVE WILL HELP PUSH OUT THE MID LEVEL
MOISTURE AND SOME SHALLOW WARM AIR ADVECTION COULD WEAKEN THE
SUBSIDENCE INVERSION AND ALLOW FOR SOME PARTIAL CLEARING. ANY
CLEARING ALONG THW SOUTHERN TIER WILL RESULT IN THE DEVELOPMENT
OF VALLEY FOG LATE TONIGHT. TEMPERATURES OVERNIGHT WILL DEPEND
GREATLY ON AMOUNT OF CLEARING WHICH CAN TAKE PLACE. WITH LITTLE
CHANGE IN AIR MASS EXPECTED WILL LEAN OVERNIGHT TEMPERATURES
TOWARD BIAS CORRECTION NUMBERS SUGGESTING UPPER 20S TO LOWER 30S
ALONG THE SOUTHERN TIER AND EAST OF LAKE ONTARIO TO THE MID AND
UPPER 30S ALONG THE LAKE PLAIN.
SHORT TERM /SUNDAY THROUGH TUESDAY/
AT THE START OF THE PERIOD AN EXPANSIVE AREA OF HIGH PRESSURE WILL
STRETCH FROM QUEBEC SOUTHWARD ACROSS THE LOWER LAKES AND DOWN THE
APPALACHIANS. SOME STRATUS MAY STILL LINGER IN THE MORNING ACROSS
THE HIGHER TERRAIN OF THE SOUTHERN TIER...BUT EXPECT CONTINUED
SUBSIDENCE AND DRYING TO FINALLY ERODE THIS AND LEAVE PLENTY OF
SUNSHINE EVERYWHERE DURING THE AFTERNOON. 850MB TEMPS OF AROUND +4C
WILL CONTINUE TO SUPPORT ABOVE AVERAGE TEMPS WITH HIGHS IN THE LOWER
50S IN MOST LOCATIONS...WITH UPPER 40S ACROSS THE NORTH COUNTRY. THE
SURFACE HIGH WILL SLOWLY DRIFT INTO THE CANADIAN MARITIMES BY
MONDAY. SOUTHEAST RETURN FLOW MAY ALLOW SOME INCREASE IN MOISTURE
DURING THE DAY ACROSS THE SOUTHERN TIER...BUT OTHERWISE EXPECT A
FAIR AMOUNT OF SUNSHINE. SIMILAR 850MB TEMPS WILL SUPPORT HIGHS IN
THE LOWER 50S AGAIN ACROSS THE LOWER ELEVATIONS...A FEW DEGREES
COOLER ACROSS HIGHER TERRAIN.
MONDAY NIGHT AND TUESDAY SIGNIFICANT MODEL DIFFERENCES BECOME
APPARENT WITH THE HANDLING OF A WEAK COASTAL SYSTEM. MOISTURE
CHANNEL IMAGERY SHOWS A WEAK SOUTHERN STREAM CUTOFF LOW MOVING
THROUGH SOUTHEAST TEXAS EARLY THIS MORNING. THE GFS CONTINUES TO
TAKE A PIECE OF THIS SYSTEM AND PLUME OF ASSOCIATED MOISTURE UP TO
THE WEST OF THE APPALACHIANS...WITH ANOTHER PIECE OF ENERGY SPAWNING
A WEAK COASTAL LOW OFF THE CAROLINAS. THIS ALLOWS A NOTABLE PERIOD
OF RAIN TO LIFT NORTH ACROSS THE CWA MONDAY NIGHT AND TUESDAY IN THE
GFS SOLUTION. THE NAM AND CANADIAN GEM EMPHASIZE THE COASTAL SYSTEM
ONLY...KEEPING ALL OF THE PRECIP ALONG THE COASTAL PLAIN MONDAY
NIGHT INTO TUESDAY. THE DIFFERENCE IN SENSIBLE WEATHER IS HUGE...
WITH A RAINY GFS SOLUTION VERSUS A DRY AND EVEN PARTLY SUNNY NAM
SOLUTION.
THE NEW 00Z ECMWF JUST COMING IN ALSO SUPPORTS THE NAM SOLUTION WITH
MOST IF NOT ALL OF THE PRECIP FOCUSING ALONG THE COAST. WILL CHOOSE
TO FOLLOW THE MODEL CONSENSUS AND THROW OUT THE GFS SOLUTION. THIS
ALLOWS US TO STAY CLOSE TO FORECAST CONTINUITY WITH A DRY FORECAST
FOR MOST OF THE CWA MONDAY NIGHT AND TUESDAY. WILL KEEP SOME LOW
CHANCE POPS EAST OF LAKE ONTARIO TO HANDLE THE POTENTIAL FOR COASTAL
MOISTURE MAKING IT BACK THAT FAR WEST.
LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/
THE NOW WELL ADVERTISED PATTERN CHANGE STILL APPEARS ON TRACK TO
ARRIVE FOR THE THANKSGIVING HOLIDAY. THE CURRENT PATTERN ACROSS THE
NOAM SECTOR IS MORE OR LESS ZONAL...WITH TRANSIENT RELATIVELY LOW
AMPLITUDE TROUGHS MOVING THROUGH THE WESTERLIES ALONG AND JUST NORTH
OF THE US/CANADIAN BORDER. THE GEFS ENSEMBLE MEAN CONTINUES TO
FORECAST THE NAO INDEX TO BECOME WEAKLY NEGATIVE BY THE END OF THE
MONTH...WITH THE PNA INDEX TRENDING POSITIVE. IN THE MEAN...THIS
SHOULD YIELD A COLDER PATTERN FOR THE GREAT LAKES AND NORTHEAST FOR
THE LAST WEEK OF NOVEMBER INTO EARLY DECEMBER WITH A TROUGH FAVORED
OVER THE EASTERN CONUS IN SUCH A PATTERN. THE INDICES ARE NOT
FORECAST TO BE PARTICULARLY STRONG HOWEVER...SO NO DRAMATIC PATTERN
CHANGE IS EXPECTED...RATHER A TREND TOWARDS COOLER AND MORE
SEASONABLE TEMPERATURES.
LOOKING AT THE DETAILS...THERE ARE STILL THE TYPICAL DIFFERENCES IN
THE HANDLING OF SHORTWAVE FEATURES AND ASSOCIATED SURFACE SYSTEMS
FOR THE SECOND HALF OF THE WEEK. THE GFS CONTINUES TO EJECT A LEAD
SHORTWAVE AND ASSOCIATED SURFACE LOW INTO THE GREAT LAKES REGION ON
WEDNESDAY WITH ANOTHER SYSTEM FOR THURSDAY AND FRIDAY AS THE MAIN
MID LEVEL TROUGH CROSSES THE REGION. THE ECMWF DOES NOT SUPPORT THIS
FIRST LOW ON WEDNESDAY...BUT DOES COME INTO AGREEMENT WITH THE
SYSTEM FOR THURSDAY/FRIDAY. THE CANADIAN GEM IS IN GOOD AGREEMENT
WITH THE GFS SOLUTION SHOWING BOTH SYSTEMS.
FOR NOW...GIVEN THE MODEL UNCERTAINTY WILL SIMPLY STICK WITH
FORECAST CONTINUITY AND KEEP CHANCE POPS FROM WEDNESDAY RIGHT
THROUGH FRIDAY. TEMPERATURES BECOME COLD ENOUGH BY THURSDAY AND
FRIDAY TO BRING PRECIP TYPE ISSUES INTO THE FORECAST. ON
THANKSGIVING...THE GFS FORECASTS 850MB TEMPS OF AROUND -4C WHILE THE
ECMWF...WITH ITS SLOWER SINGLE LOW EVOLUTION HAS 850MB TEMPS ABOVE
FREEZING STILL. HAVE LEANED TOWARDS THE GFS/GEM IDEA... BUT EVEN
THIS WOULD STILL SUPPORT MAINLY RAIN ACROSS THE LOWER ELEVATIONS
WITH A RAIN/SNOW MIX ACROSS HIGHER TERRAIN. COLDER AIR FILTERS INTO
THE REGION THURSDAY NIGHT AND FRIDAY WITH A CHANCE OF RAIN/SNOW
EVERYWHERE. AT THIS TIME...PATTERN DOES NOT LOOK AT ALL FAVORABLE
FOR ANY MEANINGFUL SNOW...WITH JUST WEAK WRAP AROUND PRECIP AND AN
UNFAVORABLE NW FLOW PREVENTING ANY SIGNIFICANT LAKE EFFECT.
AVIATION /08Z SATURDAY THROUGH WEDNESDAY/
DURING THE FORECAST PERIOD...LOW PRESSURE WILL CONTINUE TO TRACK
EAST FROM CENTRAL QUEBEC TO THE CANADIAN MARITIMES. IN THE WAKE OF THIS
FEATURE...PLENTIFUL AMOUNTS OF LOW LEVEL MOISTURE WILL CONTINUE TO
CIRCULATE ACROSS THE FORECAST AREA OVERNIGHT...THEN WILL BECOME
TRAPPED UNDER A DEVELOPING SUBSIDENCE INVERSION DURING SATURDAY AS
HIGH PRESSURE BUILDS EASTWARD FROM THE CENTRAL LAKES AND WESTERN
OHIO VALLEY.
AS A RESULT...THE SCATTERED TO BROKEN STRATOCU FOUND ACROSS THE
AREA AS OF LATE EVENING WILL TEND TO BECOME MORE WIDESPREAD
OVERNIGHT...THEN WILL LINGER IN PLACE AT LEAST INTO SATURDAY
EVENING. CIG HEIGHTS WILL START THE PERIOD IN THE HIGH MVFR TO LOW
VFR RANGE...BEFORE LOWERING TO MVFR AS THE NIGHT PROGRESSES AND
THE LOW LEVEL MOISTURE DEEPENS...WITH SOME IFR CONDITIONS EVEN
BECOMING LIKELY ACROSS PARTS OF THE SOUTHERN TIER AND NORTH COUNTRY.
DURING SATURDAY...THESE CIGS WILL THEN SLOWLY RISE BACK THROUGH THE
MVFR RANGE...BUT WILL BE UNLIKELY TO BREAK UP WITH A STRONG
SUBSIDENCE INVERSION IN PLACE.
OUTLOOK...
SATURDAY NIGHT...POSSIBLE IMPROVEMENT FROM MVFR TO VFR.
SUNDAY THROUGH TUESDAY...MAINLY VFR.
WEDNESDAY...VFR WITH CHC SHOWERS.
MARINE
WEST WINDS BLOWING DOWN THE FULL FETCH OF LAKE ONTARIO WILL CONTINUE
TO PRODUCE SMALL CRAFT CONDITIONS ON THE EAST HALF OF THE LAKE
THROUGH DAYBREAK. WINDS AND WAVES WILL SLOWLY DIMINISH TODAY...
ALTHOUGH CHOPPY CONDITIONS WILL CONTINUE. HIGH PRESSURE BUILDS OVER
THE REGION TONIGHT AND SUNDAY WITH LIGHT WINDS. AS THE HIGH
DEPARTS...EAST WINDS WILL INCREASE SOME ON MONDAY AND TUESDAY WITH
CHOPPY CONDITIONS DEVELOPING ON THE WEST HALF OF LAKE ONTARIO...BUT
CONDITIONS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY
CRITERIA.
BUF WATCHES/WARNINGS/ADVISORIES
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR
LOZ044-045.
SYNOPSIS...HITCHCOCK
NEAR TERM...TMA
SHORT TERM...HITCHCOCK
LONG TERM...HITCHCOCK
AVIATION...JJR/RSH
MARINE...HITCHCOCK
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