FXUS61 KBUF 231758
AFDBUF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1258 PM EST WED DEC 23 2009
.SYNOPSIS...
A DISTURBANCE DROPPING SOUTH FROM QUEBEC WILL BRING SOME MORE SNOW
SHOWERS TO THE AREA TODAY...PARTICULARLY ACROSS THE EASTERN LAKE
ONTARIO REGION AND SITES JUST SOUTH OF LAKE ONTARIO. HIGH PRESSURE
NOSING SOUTHWARDS FROM NORTHERN ONTARIO WILL THEN BRING US FAIR
TRANQUIL WEATHER TONIGHT THROUGH THURSDAY. THIS WILL RESULT IN IDEAL
TRAVEL CONDITIONS LEADING INTO CHRISTMAS...BUT A LARGE STORM WELL TO
OUR WEST COULD SPREAD SOME RAIN AND FREEZING RAIN OVER US CHRISTMAS
DAY THROUGH CHRISTMAS NIGHT.
&&
.NEAR TERM /THROUGH TONIGHT/...
SINCE LAST NIGHT...WE HAVE RECEIVED SEVERAL SPOTTER REPORTS OF
4-5" OF SNOWFALL IN THE LAKE SNOWS SOUTHEAST OF LAKE ONTARIO. WITH
LAKE SNOWS STILL CONTINUING IN THE WAYNE-FAR SOUTHERN OSWEGO
COUNTY CORRIDOR...HAVE HOISTED A LAKE EFFECT SNOW ADVISORY FOR
THIS AREA.
THE ADVISORY IS IN EFFECT UNTIL 7 PM THIS EVENING...BY WHICH TIME
THE COMBINATION OF A SHORTENING FETCH/INCREASING SHEAR AND A
LOWERING INVERSION SHOULD BE HELPING TO BREAK THIS ACTIVITY INTO
WEAKER/MORE SCATTERED SNOW SHOWERS. THROUGH THAT TIME...AN
ADDITIONAL 1 TO 3 INCHES OF SNOW IS EXPECTED WITHIN THE MOST
PERSISTENT SNOW BANDS...WHICH SHOULD BECOME MORE DISRUPTED WITH
THE PASSAGE OF A SHORTWAVE TROUGH THAT IS APPROACHING FROM THE
NORTH COUNTRY.
SPEAKING OF THE SHORTWAVE TROUGH...THIS FEATURE IS PRODUCING
SEVERAL BANDS OF LIGHT TO MODERATE SNOW ACROSS THE NORTH COUNTRY
AND SAINT LAWRENCE VALLEY...WITH THE LEADING NARROW BAND OF
MODERATE SNOW NOW PUSHING SOUTH ACROSS SOUTHERN JEFFERSON AND
CENTRAL LEWIS COUNTIES. EXPECT THIS ACTIVITY TO BRING ANOTHER INCH
OR SO TO PORTIONS OF THE NORTH COUNTRY NOT AFFECTED BY THE LAKE
EFFECT THROUGH EARLY TO MID AFTERNOON...AFTER WHICH TIME THE SNOW
SHOWERS WILL BECOME MORE SCATTERED IN NATURE AS THE MAIN SHORTWAVE
PASSES OFF TO THE SOUTH.
MEANWHILE FURTHER TO THE WEST...MUCH MORE SCATTERED SNOW SHOWERS
AND FLURRIES CONTINUE TO PLAGUE AREAS FROM ROCHESTER
WESTWARD...THOUGH THESE ARE PRODUCING LITTLE IF ANY ACCUMULATION.
THIS NUISANCE ACTIVITY SHOULD CONTINUE TO WIND DOWN THROUGH EARLY
AFTERNOON WITH CONTINUED WARMING AND SUBSIDENCE ALOFT.
ASIDE FROM ANY CHANGES TO THE FORECAST TO MAKE IT MESH UP BETTER WITH
THE ABOVE THINKING...HAVE ALSO LOWERED MAX TEMPS FOR THIS AFTERNOON
AS THESE WERE RUNNING TOO WARM...PARTICULARLY ACROSS THE EASTERN
THIRD OF THE FORECAST AREA.
FOR TONIGHT...ANY LINGERING LAKE EFFECT SNOW SHOULD END EARLY
TONIGHT AS THE LOW LEVEL SHEAR INCREASES. OTHERWISE...EXPECT MOSTLY
CLOUDY SKIES TO BE THE RULE AS A SHALLOW LAYER OF MOISTURE REMAINS
TRAPPED BELOW THE INVERSION WHICH WILL BE STRENGTHENED BY WARM AIR
ADVECTION ALOFT. THE ANTICIPATED CLOUD COVER AND WARM AIR ADVECTION
PATTERN WILL HELP TO KEEP AREA TEMPERATURES FAIRLY STEADY
TONIGHT...ESPECIALLY ACROSS WESTERN NEW YORK.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
THURSDAY WILL PROVE TO BE ONE OF THE THE NICEST WEATHER DAYS OF THE
WEEK AS A HIGH AMPLITUDE RIDGE WILL BE POSITIONED OVER THE EASTERN
THIRD OF THE COUNTRY. WHILE THERE WILL NOT BE ANY PRECIPITATION TO
WORRY ABOUT ON THURSDAY...MOST OF THE REGION WILL STILL HAVE TO DEAL
WITH A FAIR AMOUNT OF CLOUD COVER. FORECAST PROFILE SOUNDINGS
SUGGEST THAT A LOT OF LOW LEVEL MOISTURE WILL BE TRAPPED BENEATH A
STRONG SUBSIDENCE INVERSION...SO WE WILL LIKELY HAVE TO WAIT UNTIL
THE AFTERNOON TO GET ANY APPRECIABLE SUNSHINE. IN ANY CASE...THE DRY
WEATHER THURSDAY WILL PROMOTE PROBLEM FREE CONDITIONS FOR LAST
MINUTE HOLIDAY SHOPPERS AND TRAVELERS.
THE STRONG RIDGE WILL SLOWLY CROSS THE FORECAST AREA ON CHRISTMAS
EVE AS A SURFACE HIGH WILL GRUDGINGLY CROSS NORTHERN QUEBEC. THIS
SFC HIGH WILL NOSE SOUTHWARDS ACROSS EASTERN NEW YORK TO THE MID
ATLANTIC COAST. MEANWHILE WELL TO OUR WEST...AN EXPANSIVE UPPER LOW
WILL BECOME CONSOLIDATED OVER THE CENTRAL PLAINS. THE CORRESPONDING
SFC LOW (< 990MB) WILL LIFT NORTHWARDS ACROSS MISSOURI. THIS
SYNOPTIC SET UP WILL LIMIT THE EASTWARD ADVANCE OF ANY PCPN FROM THE
SYSTEM...SO ALL OF OUR REGION SHOULD BE ABLE TO GET THROUGH
CHRISTMAS EVEN WITHOUT ANY PRECIPITATION. WILL FOLLOW THE TREND OF
OUR CONTINUITY AND GUIDANCE FROM THE ECMWF...GFS AND SREF WHICH WILL
KEEP PCPN TO OUR WEST. GOOD FOR US...BAD FOR SANTA.
THE UPPER LEVEL RIDGE WILL CONTINUE TO VERY SLOWLY CROSS QUEBEC AND
NEW ENGLAND ON CHRISTMAS DAY WHILE THE DEEP PLAINS STORM WILL BECOME
STACKED AND FURTHER CONSOLIDATE OVER IOWA. WHILE WEAK WARM ADVECTION
WILL CONTINUE ALOFT...THE CLOSE PROXIMITY OF THE RIDGE WILL KEEP THE
LOW LEVELS UNCOMFORTABLY CLOSE TO FREEZING. AS HAS BEEN ADVERTISED
FOR SEVERAL DAYS NOW...THIS WILL LIKELY LEAD TO PROBLEMS DUE TO PCPN
TYPE. PATTERN RECOGNITION AND SIMPLE CLIMATOLOGY OF A SCENARIO WHERE
A DEEP STORM IS SO FAR TO OUR WEST WITH A COLD RIDGE ANCHORED OVER
EASTERN CANADA RAISES FLAGS/CONCERNS ABOUT FREEZING RAIN.
THIS CASE WILL BE NO DIFFERENT...BUT WITH WEAK TEMPERATURE ADVECTION
IN THE LOW LEVELS COMES WEAK MOISTURE ADVECTION. THE VARIOUS
GUIDANCE PACKAGES HAVE BEEN SLOWER AND SLOWER WITH THE ONSET OF THE
PCPN...AND THIS MAY TURN OUT TO BE A GOOD THING. MANY AREAS MAY BE
ABLE TO WARM ABOVE 32 BEFORE THE PCPN BEGINS ON CHRISTMAS DAY...BUT
FOR THOSE WESTERN AREAS THAT DO NOT...THERE COULD BE A FEW HOURS
WHERE FREEZING RAIN COULD HAVE A BIG IMPACT ON AREA ROADWAYS.
FORECAST POINT SOUNDINGS FROM BOTH THE GFS AND NAM/WRF SUGGEST THAT
TEMPS CLIMB ABV FREEZING FOR MOST AREAS BY EARLY-MID AFTERNOON ON
CHRISTMAS DAY...WITH THE ONLY AREAS OF CONCERN BEING THE DEEPER
SOUTHERN TIER VALLEYS AND SITES EAST OF LK ONTARIO. FOR THE
LATTER...THE PROFILES SUPPORT A MIX OF SLEET AND FREEZING RAIN. POPS
ON CHRISTMAS DAY WILL RANGE FROM CAT OVER THE WESTERN COUNTIES TO
LOW CHC POPS EAST OF LK ONTARIO WHERE IT MAY END BEING DRY UNTIL
NIGHTFALL.
FOR CHRISTMAS NIGHT...THE WELL STACKED STORM SYSTEM WILL BE NEARLY
STATIONARY IN THE VCNTY OF IOWA WHILE ITS ASSOCIATED FRONTAL
BOUNDARY WILL PUSH ACROSS THE OHIO VALLEY. A DEEP SWATH OF MOISTURE
(VALUES +2 STD ABV NORMAL) AHEAD OF THIS SLOW MOVING FRONT WILL MOVE
ACROSS OUR REGION...WITH A DIFFLUENT FLOW AND FAIRLY STRONG JET
DYNAMICS SUPPORTING WIDESPREAD CAT POPS. THESE POPS ARE HIGHER THAN
GUIDANCE AND GENERALLY HIGHER THAN THOSE FROM SURROUNDING WFO'S.
PCPN TYPE WILL REMAIN A PROBLEM CHRISTMAS NIGHT. SINCE THE OCCLUDED
FRONT IS NOT FORECAST TO CROSS THE FAR WESTERN COUNTIES UNTIL VERY
LATE...THE COLD AIR IN ITS WAKE WILL OBVIOUSLY STILL BE TO OUR WEST.
THIS SHOULD KEEP MAINLY LIQUID PCPN IN PLACE...ALTHOUGH SOME
FREEZING RAIN AND POSSIBLY SLEET MAY BE AN ISSUE FOR SITES EAST OF
LK ONTARIO.
ON SATURDAY...THE FRONTAL BOUNDARY WILL FINALLY CROSS THE FORECAST
AREA WHILE THE PARENT STACKED STORM WILL WOBBLE ACROSS WISCONSIN.
THE COLD AIR IN THE WAKE OF THE FRONTAL PASSAGE WILL BE SLOW TO
SUFFICIENTLY DEEPEN FOR WIDESPREAD SNOW SHOWERS...EXCEPT OVER THE
FAR WESTERN COUNTIES. WILL THEREFORE KEEP THE IDEAL OF A SLOW WEST
TO EAST TRANSITION SATURDAY AND SATURDAY NIGHT.
&&
.LONG TERM /SUNDAY THROUGH TUESDAY/...
THE CLOSED 500 MB LOW WILL CONTINUE ITS SLOW EASTWARD PROGRESSION...
BRINGING COOLER AIR ALOFT AND GENERALLY AN UNSETTLED PATTERN. BY
SUNDAY...IT SHOULD BE COLD ENOUGH FOR ANY PRECIPITATION THAT DOES
FALL TO BE SNOW. THE CLOSE PROXIMITY OF THE UPPER LOW (BUT UNCERTAIN
EXACT TRACK) WILL PREVENT ANY SIGNIFICANT SYNOPTIC LOWS FROM
DEVELOPING...BUT MAY RESULT IN INSTABILITY OR LAKE EFFECT SNOW
SHOWERS THROUGH THE PERIOD.
LOOKS TO BE A LESS THAN IDEAL SET UP FOR LAKE EFFECT FOR THE MOST
PART...WITH A GFS/EUROPEAN CONSENSUS BRINGING THE UPPER LOW TO OUR
SOUTH. HOWEVER...WITH 850 MB TEMPS DROPPING...THERE WILL BE AVAILABLE
LAKE INDUCED ENERGY...WITH SUBTLE FEATURES THE KEY. GENERALLY FOR
THE PERIOD...WITH MAINTAIN CHANCE POPS THROUGHOUT...WITH SLIGHTLY
HIGHER END CHANCE POPS IN THE TYPICALLY FAVORABLE LAKE EFFECT
REGIONS. WHILE A MAJOR EVENT IS NOT EXPECTED...AS OFTEN IS THE
CASE...PERSISTENT BANDS COULD PRODUCE LOCALLY DECENT SNOWFALL...
ALTHOUGH MOST LOCATIONS WILL NOT GET ANY SIGNIFICANT SNOWFALL
THROUGH THIS PERIOD. TEMPERATURES WILL BE COOL...BUT WITH MOSTLY
CLOUDY SKIES SHOULD HAVE MINIMAL DIURNAL SWINGS.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
BETWEEN NOW AND MIDDAY THURSDAY...AN UPPER LEVEL LOW OVER WESTERN
NEW ENGLAND WILL DRIFT SOUTHEAST INTO THE WESTERN ATLANTIC...WITH
ITS ASSOCIATED SURFACE REFLECTION FOLLOWING ALONG A SIMILAR PATH.
IN THE WAKE OF THIS LOW...RIDGING WILL BUILD EASTWARD ACROSS THE AREA
AT ALL LEVELS...ESPECIALLY ALOFT. INCREASING SUBSIDENCE ASSOCIATED
WITH THIS RIDGE WILL HELP TO TRAP LOW LEVEL MOISTURE LINGERING
BEHIND THE DEPARTING LOW...KEEPING GENERAL MVFR CIGS IN PLACE AT
LEAST THROUGH TONIGHT. AS WE GET INTO THURSDAY...SOME CLEARING MAY
BEGIN TO WORK INTO FAR SOUTHWESTERN NY STATE IN CONJUNCTION WITH
THE ARRIVAL OF THE SURFACE RIDGE AXIS...THOUGH THE PROGRESSION OF
ANY SUCH CLEARING ACROSS THE REST OF THE AREA ON THURSDAY IS
LIKELY TO BE ON THE SLOW SIDE. AS SUCH...HAVE GONE ON THE
PESSIMISTIC SIDE AND KEPT MVFR CIGS ACROSS THE REMAINING TAF SITES
THROUGH THE END OF THE PERIOD.
IN TERMS OF PRECIPITATION...OCCASIONAL SNOW SHOWERS CONTINUE TO
AFFECT PORTIONS OF THE NORTH COUNTRY IN ASSOCIATION WITH A PASSING
SHORTWAVE TROUGH...WHILE SOME LAKE SNOWS CONTINUE SOUTHEAST OF
LAKE ONTARIO. WITHIN BOTH AREAS...CONDITIONS RANGE FROM IFR TO
MVFR...AND THESE ARE EXPECTED TO CONTINUE INTO LATE THIS
AFTERNOON. AFTER THAT TIME...THE SNOWS WILL GRADUALLY WIND DOWN
EARLY THIS EVENING DUE TO A COMBINATION OF SUBSIDENCE/WARMING
ALOFT AND INCREASING SHEAR...RESULTING IN CONDITIONS IMPROVING TO
MVFR.
OUTLOOK...
FRIDAY...DETERIORATION TO IFR/MVFR WITH RAIN DEVELOPING...POSSIBLY
STARTING AS A PERIOD OF FREEZING RAIN.
SATURDAY...IFR/MVFR WITH A MIX OF RAIN AND SNOW. SOME FREEZING
RAIN POSSIBLE ACROSS THE NORTH COUNTRY IN THE MORNING.
SUNDAY AND MONDAY...MVFR/VFR WITH A CHANCE OF SNOW SHOWERS.
&&
.MARINE...
SMALL CRAFT ADVISORIES WILL REMAIN IN PLACE FOR THE NEW YORK
NEARSHORE WATERS OF LK ONTARIO THROUGH AT LEAST THIS AFTERNOON.
STRONG HIGH PRESSURE NOSING SOUTH FROM NORTHERN ONTARIO WILL PRODUCE
FRESH TO STRONG NORTHWESTERLIES ACROSS LAKE ONTARIO TODAY...WHILE A
WEAKER SFC PRESSURE GRADIENT WILL RESULT IN JUST MODERATE
NORTHWESTERLIES OVER LK ERIE.
DURING THE COURSE OF TONIGHT...THE EASTWARD DRIFTING HIGH PRESSURE
WILL WEAKEN THE GRADIENT OVER LAKE ONTARIO...THEREBY LOWERING BOTH
THE WINDS AND CORRESPONDING WAVES. ALL SMALL CRAFT ADVISORIES SHOULD
BE ALLOWED TO EXPIRE BY MIDNIGHT.
ON THURSDAY...THE SFC HIGH WILL DRIFT A LITTLE FURTHER TO THE EAST.
THIS ALLOW WINDS TO VEER TO THE NORTHEAST ACROSS BOTH LAKES WITH
WINDS AND WAVES REMAINING BELOW SCA CRITERIA. THE WINDS WILL FRESHEN
A BIT THURSDAY NIGHT AS THEY BECOME MORE EASTERLY.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR
NYZ004>006.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR
LOZ042>045.
&&
$$
SYNOPSIS...RSH
NEAR TERM...JJR/TJP
SHORT TERM...RSH
LONG TERM...APFFEL/RSH
AVIATION...JJR
MARINE...RSH
