FXUS61 KBUF 261746
AFDBUF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1246 PM EST SAT DEC 26 2009
.SYNOPSIS...
LOW PRESSURE OVER IOWA WILL MOVE SLOWLY TO THE NORTHEAST TODAY AND
TONIGHT...THEN REACH JAMES BAY ON SUNDAY. OCCASIONAL SHOWERS FORMING
WELL AHEAD OF THIS SYSTEM WILL CONTINUE THIS MORNING...THEN TAPER
OFF TO SCATTERED SNOW SHOWERS THIS AFTERNOON AND TONIGHT. SOME
POCKETS OF FREEZING RAIN MAY LINGER ACROSS THE NORTH COUNTRY THIS
MORNING. A FEW MORE SNOW SHOWERS ARE POSSIBLE ON SUNDAY BEFORE A
STRONG COLD FRONT BRINGS A BETTER CHANCE ON SNOW MONDAY...FOLLOWED
BY COLDER TEMPERATURES FOR TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
WATER VAPOR LOOP EARLY THIS MORNING SHOWING A MID LEVEL CUTOFF LOW
LIFTING OUT OF THE MID MISSISSIPPI VALLEY INTO THE SOUTHERN GREAT
LAKES/UPPER MIDWEST. AT THE SURFACE...A WEAK WAVE IS LIFTING
SLOWLY NORTHEAST FROM THE MID ATLANTIC REGION...WHILE AN UPSTREAM
OCCLUDED FRONT PUSHES ACROSS SOUTHERN ONTARIO AND OHIO. A MODEST
SOUTHEASTERLY LOW LEVEL JET CONTINUING TO PROVIDE PLENTY OF
MOISTURE TRANSPORT INTO THE REGION NORTH OF THE SURFACE WAVE AND
AHEAD OF THE APPROACHING FRONT.
REGIONAL RADARS SHOWING A BLOSSOMING AREA OF PRECIP OVER ALL OF
WESTERN NEW YORK THIS MORNING. MOST OF THIS IS RAIN...BUT THE FAR
WESTERN EDGE ACROSS MUCH OF CHAUTAUQUA COUNTY HAS CHANGED TO SNOW AS
COLDER AIR SLOWLY FILTERS IN. EXPECT THE RAIN/SNOW LINE TO GRADUALLY
WORK EAST ACROSS WESTERN NY TODAY...REACHING ROCHESTER BY LATE
AFTERNOON. TEMPERATURES WILL FALL...BUT WILL LIKELY STAY AT OR JUST
ABOVE FREEZING THROUGH LATE AFTERNOON ACROSS THE LOWER ELEVATIONS.
THIS WILL PREVENT ANY REAL ACCUMULATION IN MOST AREAS...EXCEPT FOR
ACROSS THE HIGHER TERRAIN OF THE SOUTHERN TIER WHERE TEMPS WILL DROP
BELOW FREEZING...WITH AN INCH OR TWO ACCUMULATION.
EAST OF LAKE ONTARIO...BOUNDARY LAYER TEMPERATURES HAVE RISEN ABOVE
FREEZING EVERYWHERE IN JEFFERSON AND LEWIS COUNTIES. THIS HAS ENDED
THE FREEZING RAIN RISK...AND WILL THEREFORE CANCEL THE WINTER
WEATHER ADVISORY.
COLDER AIR WILL FILTER BACK ACROSS THE REGION IN WAKE OF THE FRONT
LATER THIS MORNING AND DURING THE AFTERNOON. 850 MB TEMPERATURES
WILL DROP TO NEAR -7C IN THE WEST BY THE END OF THE DAY AND FROM -5C
TO -8C FOR THE ENTIRE AREA TONIGHT. MODEL SOUNDINGS SUGGEST THAT THE
RAIN WILL GRADUALLY CHANGE OVER TO SNOW IN THE COLD AIR ADVECTION
REGIME STARTING LATE THIS MORNING IN THE FAR WEST AND THEN FOR THE
ENTIRE AREA THROUGH TONIGHT. PRECIPITATION WILL BE DIMINISHING AS
THE COLD AIR DEEPENS...THEREFORE ANY ACCUMULATIONS WILL BE LIMITED
WITH THE GREATEST POTENTIAL FOR ACCUMULATIONS BEING TERRAIN DRIVEN
ACROSS THE HIGHER ELEVATIONS OF THE SOUTHERN TIER AND THE TUG HILL
WITH SOME 1-2 INCH ACCUMULATIONS POSSIBLE BY SUNDAY MORNING.
&&
.SHORT TERM /SUNDAY THROUGH TUESDAY/...
THE OCCLUDED FRONT THAT STRETCHES EAST OF THE MIDWEST LOW WILL MOVE
EAST INTO NEW ENGLAND ON SUNDAY. A WELL DEFINED DRY SLOT FOLLOWING
THIS FRONT WILL BE CENTERED OVER WESTERN AND CENTER NEW YORK THROUGH
AT LEAST THE FIRST HALF OF SUNDAY. DURING THE AFTERNOON...THE AREA
WILL COME UNDER INCREASING INFLUENCE OF THE MAIN UPPER LEVEL LOW
WHICH WILL BE APPROACHING FROM THE CENTRAL GREAT LAKES. WITH LOW
MOISTURE EXPECTED TO INCREASE...WILL MAINTAIN A GENERAL WEST TO EAST
INCREASE IN SNOW SHOWER CHANCES AS THE DAY WEARS ON. WITH 850 MB
TEMPS FORECAST TO DROP TO THE -8C TO -10C RANGE BY EARLY TO MID
AFTERNOON...THE AIRMASS WILL ALSO BECOME COLD ENOUGH FOR SOME LAKE
ENHANCEMENT NORTHEAST THE LAKE ERIE...THOUGH THIS SHOULD REMAIN
LIMITED IN SCOPE BY RELATIVELY LOW INVERSION HEIGHTS OF 5-6 KFT AND
A FAIR AMOUNT OF SHEAR. FOR NOW...WILL JUST INDICATE THIS POTENTIAL
ENHANCEMENT WITH SOME LOW LIKELY POPS ACROSS THE NIAGARA FRONTIER.
SUNDAY NIGHT...SCATTERED SNOW SHOWERS WILL CONTINUE ACROSS THE AREA
AS THE MAIN UPPER LEVEL LOW CENTER PUSHES EAST ACROSS NEW YORK STATE
AND THE COLD AIR DEEPENS. EXPECT MORE LAKE ENHANCED SNOWS OFF BOTH
LAKES ERIE AND ONTARIO...WITH THE ACTIVITY TENDING TO SHIFT
SOUTHWARD WITH TIME AS THE STEERING WINDS VEER FROM SOUTHWEST TO
WEST. THIS SAID...THE LAKE ENHANCEMENT WILL AGAIN BE HELD IN CHECK
BY THE CLOSE PROXIMITY OF THE UPPER LEVEL LOW...WHICH WILL RESULT IN
A HIGH AMOUNT OF SHEAR. AS SUCH...WILL KEEP PROBABILITIES IN THE
EXPECTED LAKE EFFECT AREAS CONFINED TO THE LOW LIKELY RANGE FOR THIS
PERIOD AS WELL.
ON MONDAY...A POLAR VORTEX DROPPING SOUTH FROM HUDSON BAY WILL
REINFORCE THE UPPER LEVEL TROUGH THAT WILL BE IN PLACE OVER THE
LOWER GREAT LAKES AND NEW ENGLAND. AN ARCTIC FRONT THAT IS
ASSOCIATED WITH THE DEEPENING UPPER LEVEL TROUGH WILL CROSS
THE AREA LATE MONDAY AFTERNOON. A GENERAL BURST OF SNOW SHOWERS IS
EXPECTED TO ACCOMPANY THE FRONTAL PASSAGE...WHICH WILL BE COVERED
EVERYWHERE WITH LIKELY POPS. LAKE EFFECT SNOW SHOWERS WILL ALSO
CONTINUE DURING THE DAY OFF BOTH LAKES...AND MAY EVEN BECOME A BIT
BETTER ORGANIZED FOR A TIME IN ADVANCE OF THE APPROACHING FRONT AS
THE SHEAR RELAXES A BIT BEHIND THE DEPARTING INITIAL UPPER LOW.
WHILE THE LOCATION OF THE LAKE SNOWS IS STILL SOMEWHAT IN QUESTION
GIVEN THE DIFFERING DEGREE TO WHICH THE VARIOUS MODELS BACK THE
STEERING WINDS AHEAD OF THE APPROACHING FRONT...IT STILL LOOKS LIKE
THE BOUNDARY LAYER WINDS WILL REMAIN WESTERLY ENOUGH TO KEEP THE
STEADIER LAKE SNOWS JUST SOUTH OF THE IMMEDIATE BUFFALO AND
WATERTOWN AREAS. HOWEVER...SHOULD THE WINDS BACK A BIT FURTHER THAN
CURRENTLY INDICATED...WHICH IS A POSSIBILITY GIVEN THE OVERALL
SYNOPTIC SETUP AND THE POTENTIAL FOR LAKE AGGREGATE TROUGHING TO
ENHANCE THE OVERALL CYCLONIC FLOW...IT IS QUITE POSSIBLE THAT THE
LAKE SNOWS COULD MAKE IT A BIT FURTHER NORTH AND REACH THE BUFFALO
AND WATERTOWN AREAS FOR A TIME DURING THE DAY. FOR NOW...WILL
JUST MAINTAIN SLIGHTLY ENHANCED POPS IN THE EXPECTED LAKE EFFECT
AREAS.
FOLLOWING THE PASSAGE OF THE SURFACE FRONT MONDAY EVENING...
THE WINDS WILL SHIFT TO THE NORTHWEST AND ALLOW MUCH COLDER AIR
ALOFT TO ADVECT ACROSS THE REGION. THIS WILL RESULT IN ANY LAKE
SNOWS SHIFTING SOUTHWARD TO AREAS SOUTHEAST OF THE LAKES AND
BECOMING MORE MULTIBANDED IN NATURE...THEN WEAKEN WITH TIME WITH A
LOWERING CAP AND DECREASING SYNOPTIC SCALE MOISTURE. WILL THUS KEEP
LIKELY POPS IN PLAY IN THE EXPECTED LAKE EFFECT AREAS AT THE START
OF THE PERIOD...THEN SLOWLY DIMINISH THESE DURING THE NIGHT AS THE
ABOVE INHIBITING FACTORS COME INTO PLAY. ELSEWHERE...WILL JUST
MAINTAIN A GENERAL CHANCE OF SNOW SHOWERS GIVEN THE COLD
NORTHWESTERLY FLOW ACROSS THE LAKES.
&&
.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
LAKE EFFECT SNOWS WILL CONTINUE TUESDAY AS A COLD NORTHWEST FLOW
REMAINS INTACT ACROSS THE EASTERN GREAT LAKES. THIS WOULD PLACE SNOW
OFF LAKE ERIE ACROSS SKI COUNTRY OF THE SOUTHERN TIER AND OFF LAKE
ONTARIO ACROSS THE NORTHERN GENESEE AND FINGER LAKES REGION. AS HIGH
PRESSURE MOVES IN FROM THE WEST DURING THE AFTERNOON...LAKE INDUCED
EQUILIBRIUM LEVELS WILL FALL AND THE LOW LEVEL SHEAR WILL INCREASE.
THIS WILL ALLOW THE LAKE EFFECT SNOWS TO TAPER TO FLURRIES TUESDAY
AFTERNOON AND EVENING.
WITH 850 MB TEMPERATURES EXPECTED TO RANGE FROM FROM AROUND -16C TO
THE WEST AND -22C TOWARDS THE EAST...MANY LOCATIONS WILL STRUGGLE TO
REACH 20F ON TUESDAY.
MUCH OF THE REGION WILL BE DRY OVERNIGHT TUESDAY...OUTSIDE OF
DIMINISHING LAKE SNOWS. TEMPERATURES WILL FALL TO BELOW AVERAGE
READINGS ACROSS THE CWA.
HIGH PRESSURE IS FORECAST TO TRACK EAST ACROSS NEW YORK STATE AND
NEW ENGLAND WEDNESDAY...WHILE AN ALBERTA CLIPPER HEADS SOUTHEAST
TOWARD THE UPPER MIDWEST. EXPECT DRY CONDITIONS ON WEDNESDAY...BUT
CLOUDS WILL INCREASE DURING THE AFTERNOON AS THE CLIPPER APPROACHES.
A GENERAL AREA OF LIGHT SNOW SHOWERS WILL DEVELOP WEDNESDAY NIGHT
AND THURSDAY AS WARM AIR ADVECTION SETS UP AHEAD OF THE CLIPPER.
SNOW SHOWERS WILL CONTINUE THURSDAY NIGHT AND FRIDAY WITH THE LOW
FORECAST TO STALL OVER THE LOWER GREAT LAKES.
AFTER A RATHER COLD START TO THE FORECAST PERIOD...TEMPERATURES WILL
MODERATE TO NEAR AVERAGE LEVELS THURSDAY AND FRIDAY.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
REGIONAL RADAR IMAGERY SHOWING A WIDESPREAD AREA OF PRECIPITATION
ACROSS ALL OF WESTERN NEW YORK EARLY THIS AFTERNOON. THIS WILL
CONTINUE TO EXPAND SLOWLY EAST THROUGH THIS EVENING...WITH A
DIMINISHING TREND FROM WEST TO EAST OVERNIGHT. MOST OF THE PRECIP IS
STILL IN THE FORM OF RAIN...EXCEPT FOR ACROSS SOUTHWEST NY WHERE
RAIN HAS MIXED WITH WET SNOW. EXPECT THIS SAME GENERAL TREND TO
FOLLOW THE PRECIP SHIELD EAST...WITH THE LAST FEW HOURS MIXING WITH
OR CHANGING TO WET SNOW. THE CONTINUED PRECIPITATION ALONG WITH BR
FROM SATURATED LOW LEVELS WILL PRODUCE WIDESPREAD MVFR/IFR VSBY
THROUGH THE REST OF THE AFTERNOON.
WIDESPREAD MVFR/IFR CIGS WILL CONTINUE ACROSS WESTERN NY THROUGH THE
REST OF THE AFTERNOON. THIS EVENING A DRY SLOT OVER OHIO AND CENTRAL
LAKE ERIE WILL WORK EAST ACROSS THE AREA...WITH CIGS IMPROVING TO
VFR AND EVEN SCATTERING OUT FOR SEVERAL HOURS. FINALLY ON SUNDAY
WRAP AROUND MOISTURE WILL ARRIVE WITH A VFR CIG RETURNING. EXPECT
SOME MVFR TO DEVELOP ACROSS THE HIGHER TERRAIN OF THE SOUTHERN TIER
WITH INCREASING UPSLOPE FLOW.
FARTHER EAST AT ART...EXPECT A BREAK IN THE RAIN THROUGH LATE
AFTERNOON WITH VFR CONDITIONS. BY EVENING RAIN WILL INCREASE WITH
CIGS/VSBY DETERIORATING TO MVFR...THEN EVENTUALLY TO IFR OVERNIGHT.
RAIN WILL MIX WITH WET SNOW LATE TONIGHT BEFORE ENDING. THE DRY SLOT
WILL FINALLY REACH KART BY AROUND 12Z SUNDAY WITH CONDITIONS
IMPROVING TO VFR.
OUTLOOK...
MONDAY...SNOW SHOWERS LIKELY WITH IFR/MVFR.
TUESDAY...MVFR/VFR WITH A CHANCE OF SNOW SHOWERS. LOCAL IFR IN LAKE
EFFECT SNOW SOUTHEAST OF THE LAKES.
WEDNESDAY AND THURSDAY...MVFR/VFR WITH A CHANCE OF SNOW SHOWERS.
&&
.MARINE...
THE EAST TO SOUTHEASTERLY FLOW HAS WEAKENED ENOUGH AS OF MID MORNING
TO ALLOW CONDITIONS TO FALL BELOW ADVISORY CRITERIA ACROSS THE
NEARSHORE WATERS OF LAKE ONTARIO...THEREFORE THE REMAINING SMALL
CRAFT ADVISORIES HAVE BEEN CANCELLED. WHILE THERE STILL COULD BE
SOME CHOPPY CONDITIONS FOR A FEW MORE HOURS...WINDS AND WAVES WILL
CONTINUE TO SUBSIDE THROUGH THE AFTERNOON AS THE PRESSURE GRADIENT
WEAKENS FURTHER.
THE NEXT ROUND OF POSSIBLE SCA CONDITIONS IS EXPECTED SUNDAY NIGHT
INTO MONDAY AS AN ARCTIC COLD FRONT APPROACHES AND CROSSES THE
REGION.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TJP
NEAR TERM...HITCHCOCK/TMA
SHORT TERM...TJP
LONG TERM...TJP
AVIATION...HITCHCOCK
MARINE...JJR/TJP
