FXUS61 KBUF 260902
AFDBUF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
402 AM 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 SCATTERED TO NUMEROUS SHOWER ACTIVITY ACROSS
THE REGION...ESPECIALLY WEST OF THE FINGER LAKES. BOUNDARY LAYER
TEMPERATURES ARE ABOVE FREEZING OVER NEARLY THE ENTIRE AREA. THE
ONLY EXCEPTION WAS FOUND ACROSS PORTIONS OF THE NORTH COUNTRY...
PRIMARILY OVER THE TRUG HILL AND ALONG THE SAINT LAWRENCE VALLEY.
BOUNDARY LATER TEMPERATURES WILL LIKELY REMAIN STEADY OF RISE A
BIT MORE THIS MORNING AHEAD OF THE FRONT...SO JUST RAIN WILL FALL
EVERYWHERE THIS MORNING WITH ANY LINGERING FREEZING RAIN ACROSS
THE NORTH COUNTRY MORE THAN LIKELY CHANGING OVER TO PLAIN RAIN.
FOR NOW WILL KEEP THE WINTER WEATHER ADVISORY FOR THE NORTH
COUNTRY BUT WILL LIKELY NEED TO CANCEL THIS EARLIER THAN ITS 1 PM
EXPIRATION.
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 ACROSS 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 /09Z SATURDAY THROUGH WEDNESDAY/...
A DEEP STORM SYSTEM SPINNING IN PLACE OVER IOWA WILL CONTINUE TO
CIRCULATE RELATIVELY MILD AIR NORTHWARDS FROM THE OHIO VALLEY
OVERNIGHT. THIS AIR HAS ALREADY OVERSPREAD THE WESTERN HALF OF THE
STATE AND WILL DO THE SAME ACROSS THE EASTERN LAKE ONTARIO COUNTIES
AS THE NIGHT PROGRESSES. THE MILDER AIR WILL THUS KEEP ANY SHOWERS
IN LIQUID FORM FOR MOST AREAS...ALTHOUGH SOME POCKETS OF FREEZING
RAIN WILL STILL BE FOUND AT SOME OF THE SMALLER REGIONAL/LOCAL
AIRFIELDS EAST OF WATERTOWN THROUGH DAYBREAK.
OTHERWISE...CIGS WILL GENERALLY BE AT MVFR LEVELS FOR THE REST OF
THE NIGHT. IFR WILL BE FOUND AT KJHW WITH LIFR CONDITIONS POSSIBLE.
ON SATURDAY...PRECIPITATION WILL BECOME A LITTLE MORE WIDESPREAD
ONCE AGAIN OVER THE WESTERN COUNTIES AHEAD OF A FRONTAL SYSTEM.
WHILE THE PRECIPITATION WILL START AS JUST RAIN...IT WILL MIX WITH
THEN CHANGE TO SNOW DURING THE COURSE OF THE DAY. THIS WILL
ESPECIALLY BE THE CASE ACROSS THE HIGHER TERRAIN OF THE WRN SOUTHERN
TIER WHERE SITES SUCH AS KJHW AND KELZ WILL CHANGE TO JUST SNOW. AS
A RESULT...IFR CIGS WILL BE ACCOMPANIED BY IFR/MVFR VSBYS IN SNOW.
AIRFIELD CONDITIONS WILL LIKELY DETERIORATE AS WELL. FOR MOST SITES
THOUGH...MVFR CONDITIONS WILL BE IN PLACE.
ALONG WITH THE IFR TO MVFR CIGS OVERNIGHT...THERE WILL BE SOME LOW
LEVEL WIND SHEAR PROBLEMS TO DEAL WITH. THIS WILL MAINLY BE THE CASE
OVER THE WRN COUNTIES WHERE WINDS OF 40 TO 50 KNOTS WILL BE FOUND
ARND 2K FT WITH WINDS AS HIGH AS 60 KNOTS JUST ABV THAT.
OUTLOOK...
SUNDAY AND MONDAY...MVFR WITH A CHANCE OF SNOW SHOWERS...WITH
LIMITED LAKE SNOWS POSSIBLE EAST OF THE LAKES.
TUESDAY...MVFR/VFR WITH A CHANCE OF SNOW SHOWERS.
WEDNESDAY...MVFR/VFR WITH A CHANCE OF SNOW.
&&
.MARINE...
A STIFF EAST-SOUTHEASTERLY FLOW WILL RESULT IN WINDS/WAVES REMAINING
ABOVE SMALL CRAFT ADVISORY CRITERIA ON LAKE ONTARIO THROUGH THIS
MORNING. WIND AND WAVES WILL SUBSIDE THIS AFTERNOON ON BOTH LAKES AS
THE PRESSURE GRADIENT WEAKENS.
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...WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
NYZ007-008.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR LOZ042-
043.
&&
$$
SYNOPSIS...TJP
NEAR TERM...TMA
SHORT TERM...TJP
LONG TERM...TJP
AVIATION...RSH
MARINE...TJP
