FXUS61 KALY 052338
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
640 PM EST SAT DEC 5 2009
.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL STRENGTHEN AS IT HEADS NORTHEAST ALONG
NEW ENGLAND COAST TONIGHT WITH SNOW TAPERING OFF. HIGH PRESSURE WILL
BUILD IN ON SUNDAY AND SHIFT TO OUR EAST AND OFFSHORE MONDAY. A WEAK
LOW PRESSURE SYSTEM WILL MOVE ACROSS THE REGION MONDAY AFTERNOON AND
NIGHT. A MORE SIGNIFICANT SYSTEM WILL IMPACT REGION DURING IN THE
MIDDLE OF THE WEEK BRINGING WIDESPREAD PRECIPITATION TO THE AREA.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
EXPANDED WINTER WEATHER ADVISORY FOR SNOW ACROSS THE EASTERN
CATSKILLS...HELDERBERGS...SCHOHARIE COUNTY...THE CENTRAL AND
NORTHERN TACONICS...THE MID HUDSON VALLEY AND SOUTHERN VERMONT.
BASED IN SNOWFALL REPORTS...REFER TO PUBLIC INFORMATION
STATEMENT...AMOUNT OF PRECIPITATION REPORTED AND ECHO INTENSITY
ON RADAR HAD TO EXPANDED THE ADVISORY THIS EVENING. INITIALLY SNOW
WAS ACCUMULATING ONLY ON GRASSY SURFACE AND DECKS AND SUCH AND NOT
ROADS...HOWEVER WITH THE TEMPERATURES FALLING SNOW IS NOW
ACCUMULATING ON SOME ROADWAYS WHICH WILL MAKE FOR SLICK TRAVEL. SNOW
EXPECTED TO TAPER OFF LATER THIS EVENING AND THERE ARE SIGNS OF THIS
IN BINGHAMTON RADAR.
PREVIOUS DISCUSSION ISSUED AT 357 PM...NO CHANGES TO WINTER WEATHER
ADVISORY HEADLINES AT THIS TIME...ALTHOUGH EXPECTING SLIGHTLY
HIGHER TOTAL SNOW ACCUMULATIONS OF 2-4" FOR THE CAPITAL
REGION...SCHOHARIE VALLEY AND HELDERBERGS. INCREASED ACCUMS TO
1-3" FOR THE LAKE GEORGE SARATOGA REGION AND CENTRAL/EASTERN
MOHAWK VALLEY AS WELL. STILL EXPECTING AMOUNTS OF 2-4" IN THE MID
HUDSON VALLEY...TACONICS AND SOUTHERN VERMONT...WITH GENERALLY
2-6" IN THE ADVISORY AREA ACROSS DUTCHESS...BERKSHIRE AND
LITCHFIELD COUNTIES.
SNOW HAS DEVELOPED ACROSS THE ENTIRE AREA...WITH OCCASIONAL
MODERATE SNOW FROM GENERALLY A SARATOGA TO CAPITAL REGION TO
SCHOHARIE LINE AND POINTS SOUTH AND EAST...WITH LIGHT SNOW TO THE
NORTH AND WEST. SOME ENHANCEMENT EVIDENT IN RADAR IMAGERY WITH SMALL
SCALE BANDING TAKING PLACE WHERE IT IS SNOWING MODERATELY. VIS
SATELLITE IMAGERY DEPICTING SOME OF THESE "BANDLETS" NICELY. SNOW IS
ACCUMULATING MAINLY ON GRASSY SURFACES WITH SURFACE AIR TEMPS MAINLY
IN THE LOWER TO MID 30S. AFTER DARK HOWEVER...SURFACE AND GROUND
TEMPS WILL LIKELY COOL ENOUGH FOR PAVED AREAS TO EXPERIENCE SOME
MINOR ACCUMULATIONS. THE STRONGEST AND MOST ORGANIZED AREA OF
FRONTOGENESIS STILL FORECAST TO REMAIN JUST TO OUR SOUTH AND EAST
ALONG COASTAL AREAS AND EASTERN NEW ENGLAND...SO NOT EXPECTING ANY
WARNING LEVEL ACCUMULATIONS. HAVE INCREASED QPF FOR AREAS WHERE
ENHANCEMENT IS CURRENTLY OCCURRING...WITH SNOW-LIQUID RATIOS AROUND
8 OR 9 TO 1 UNTIL AFTER DARK...INCREASING TO AROUND 10 OR 11 TO 1
THEREAFTER.
SNOW WILL GRADUALLY DECREASE IN INTENSITY BY MID EVENING...THEN
TAPER OFF BY AROUND LATE EVENING. OVERNIGHT WINDS WILL SHIFT TO THE
NORTHWEST AS THE STORM SYSTEM MOVES FARTHER OUT TO SEA WITH COLDER
AIR FILTERING IN WITH 850 MB TEMPS APPROACHING -8C TO -12C ACROSS
THE AREA BY 12Z SUNDAY. MIN TEMPS EXPECTED TO GENERALLY BE IN THE
20S...WITH SOME TEENS IN PORTIONS OF THE ADIRONDACKS.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY NIGHT/...
RIDGING BUILDS INTO REGION SUNDAY THEN SHIFTS EAST AND OFFSHORE
MONDAY. SOME LAKE EFFECT SHOWERS ARE EXPECTED SUNDAY IN NORTHWEST
FLOW. ALOFT WILL HAVE FAST FLOW. A PIECE OF ENERGY WILL BE EJECTED
FROM THE UPPER LOW OVER THE WEST COAST. THIS SHORT WAVE WILL FLY
ACROSS THE CONUS AND REACHING THE NORTHEAST DURING MONDAY AFTERNOON.
THERE WILL BE A WEAK REFLECTION AT THE SURFACE. A STRONGER LOW IS
FORECAST TO DEVELOP OFF THE NEW ENGLAND MONDAY NIGHT...BUT WILL MOVE
AWAY FROM THE REGION. COLD AIR WILL BE IN PLACE WITH CHANCES
FOR SNOW SHOWERS ESPECIALLY NORTH AND WEST OF THE CAPITAL
DISTRICT. RIDGING BUILDS IN FOR TUESDAY AND SHOULD DOMINATE WELL
INTO TUESDAY NIGHT. MODEL GUIDANCE IS IN GOOD AGREEMENT WITH
TEMPERATURES...SEASONABLE.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
HPC GUIDANCE. MODELS ARE NOW IN BETTER AGREEMENT CONCERNING THE
UPCOMING MID-WEEK STORM FROM TWO CYCLES AGO. BOTH THE GFS AND ECMWF
TRACK LOW PRESSURE FROM NORTHERN ILLINOIS/INDIANA EARLY SATURDAY TO
ABOUT LAKE HURON BY WEDNESDAY EVENING...WITH A WEAK SHALLOW COASTAL
LOW MOVING RAPIDLY UP THE EAST COAST THROUGH WEDNESDAY NIGHT. THESE
SYSTEMS COMBINE ENERGIES...CREATING A STRONG...BROAD LOW COVERING
THE ENTIRE NORTHEAST AS IT PASSES THROUGH WEDNESDAY NIGHT. THE
ECMWF IS WARMER...PROBABLY UNREALISTICALLY SO.
BUT BOTH MODELS RAPIDLY POUR IN THE COLD AIR WITH SIMILAR TIMING
BEHIND THE RAPIDLY ADVANCING COLD FRONT WEDNESDAY NIGHT.
PRECIPITATION MAY BEGIN AS SNOW IF IT STARTS EARLY ENOUGH. WARM AIR
OVERRIDING WILL BE STRONG DURING THE PERIOD...BUT THE BIG QUESTION
IS WHETHER THERE WILL BE SUFFICIENT WARM SCOURING DOWN TO THE
SURFACE BY EXPECTED EAST SOUTHEASTERLY SURFACE WINDS TO WARM THINGS
UP SO WE CAN AVOID A MAJOR FREEZING RAIN SITUATION. BASICALLY...IT
COULD VERY WELL DEPEND ON HOW COLD TUESDAY NIGHT GETS.
WE HAVE HIGHS MAINLY IN THE UPPER 30S AND LOWER 40S DOWN THE LOWER
MID HUDSON VALLEY FOR WEDNESDAY...BUT THE GFS...AND ESPECIALLY THE
ECMWF...ARE HINTING AT GREATER WARM SURFACE ADVECTION. FROM THE
CAPITAL REGION NORTH AND WEST...IT IS LOOKING MORE LIKE SNOW TO A
MIX BEFORE CHANGING BACK TO SNOW SHOWERS WEDNESDAY NIGHT. TO THE
SOUTH... MAINLY DOWN THE VALLEY...IF IT STARTS AS SNOW...IT SHOULD
CHANGE QUICKLY OVER TO RAIN. AROUND POUGHKEEPSIE...LITTLE OR NO
SNOW ACCUMULATION IS LIKELY ATTM UNTIL BEHIND THE FRONT. OVERALL
QPFS ARE ONLY SLIGHTLY MORE IMPRESSIVE THAN TWO RUNS AGO.
WESTERLY WINDS PICK UP AS THE GRADIENT TIGHTENS BEHIND THE FRONT...
AND THIS COULD PERSIST THROUGH THURSDAY NIGHT. A BROAD PATTERN OF
LAKE-ENHANCED WRAP-AROUND WILL LIKELY SET UP...AND A COUPLE OF
INCHES OF SNOW ACCUMULATION IS NOT OUT OF THE QUESTION...
PARTICULARLY IN THE WESTERN ADIRONDACKS AND THE CATSKILLS.
BY EARLY FRIDAY...THE EFFECTS OF THE COMBINED LOW DISSIPATE AS IT
TRACKS UP THROUGH THE CANADIAN MARITIMES. HIGH PRESSURE RIDGES IN
FROM THE SOUTHEAST COASTAL REGION...AND THE SNOW SHOWERS AND
FLURRIES GRADUALLY WIND DOWN. BUT THERE WILL BE AN ABUNDANCE OF
CLOUDINESS AND NO WARMING DURING THE REMAINDER OF THE PERIOD. IN
FACT...THOUGH 500 MB HEIGHTS BEGIN TO REBOUND NICELY LATE IN THE
WEEK FROM LOWS AROUND 515...SURFACE HIGH TEMPERATURES WILL BE AT
THEIR LOWEST LEVELS AT THE END OF THE WEEK...WITH MOST LOCATIONS
REMAINING BELOW FREEZING. HOWEVER...THIS IS ONLY A FEW DEGREES
BELOW NORMAL. OVERNIGHT LOWS WILL BE MAINLY IN THE 15 TO 25 DEGREE
RANGE FRIDAY NIGHT.
&&
.AVIATION /00Z SATURDAY THROUGH THURSDAY/...
STEADY -SN WILL GRADUALLY COME TO AN END THIS EVENING AS THE
OFFSHORE LOW PULLS FURTHER AWAY. MAINLY IFR CONDITIONS IN SNOW AT
THE KGFL/KALB/KPOU TAF SITES WILL TRANSITION TO MVFR CONDITIONS
EARLY IN THE TAF PERIOD...THEN BECOME VFR BETWEEN 05Z AND 07Z AS THE
SNOW ENDS. THE SNOW WILL END FIRST AT KGFL WITH IMPROVEMENT TO VFR
CONDITIONS OCCURING AROUND 05Z...AROUND 06Z AT KALB...AND 07Z AT
KPOU.
VFR CONDITIONS WILL PREVAIL THEREAFTER THROUGH THE END OF THE TAF
PERIOD AT 00Z MONDAY AT ALL THREE TAF SITES.
SURFACE WINDS WILL BE NORTH AT 5 TO 10 KTS TO START THE TAF PERIOD
AT ALL THREE LOCATIONS WITH SOME GUSTS TO OVER 15 KTS. DURING THE
NIGHT THE WINDS WILL SLOWLY SHIFT TO NORTHWEST AT 5 TO 10 KTS AND
EVENTUALLY TO WESTERLY ON SUNDAY WHEN WINDS SHOULD INCREASE DUE TO
MIXING TO 10 TO 15 KTS WITH SOME GUSTS TO 20 KTS OR MORE.
OUTLOOK...
MON...VFR/MVFR...CHC -SHSN.
TUE...VFR...NO SIG WX.
WED...MVFR/IFR. A WINTRY MIX OF PRECIP LIKELY.
THUR...VFR/MVFR...CHC -SHSN. WINDY.
&&
.HYDROLOGY...
NO HYDRO PROBLEMS EXPECTED THROUGH EARLY IN THE WEEK. PRECIPITATION
WILL BE IN THE FORM OF SNOW. AN INTENSE STORM WILL IMPACT THE
REGION MID WEEK POTENTIALLY BRINGING SIGNIFICANT PRECIPITATION TO
THE AREA. AT THIS TIME...MODEL GUIDANCE INDICATES A STORM TRACK
THAT WILL PASS TO OUR WEST WHICH WILL BRING WARMER AIR INTO THE
REGION. HOWEVER...THERE ARE INDICATIONS OF SECONDARY LOW
DEVELOPMENT ALONG THE COAST. INITIALLY...IT WILL BE COLD ENOUGH
FOR SNOW ACROSS THE ENTIRE FORECAST AREA...HOWEVER AS WARMER AIR
WORKS IN P-TYPE WILL CHANGE WITH MIXED PRECIPITATION POSSIBLE.
UNCERTAINTY EXISTS WITH REGARDS TO QPF AMOUNTS AND P-TYPE AS ANY
CHANGE IN THE TRACK OF THE STORM AND OR THE DEVELOPMENT OF A
SECONDARY LOW ALONG THE COAST WILL HAVE AN IMPACT ON P-TYPE.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING
OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE
VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON
OUR WEBSITE.E /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...WINTER WEATHER ADVISORY UNTIL 1 AM EST SUNDAY FOR CTZ001-013.
NY...WINTER WEATHER ADVISORY UNTIL 1 AM EST SUNDAY FOR NYZ047-048-
051-054-058>061-063>066.
MA...WINTER WEATHER ADVISORY UNTIL 1 AM EST SUNDAY FOR MAZ001-025.
VT...WINTER WEATHER ADVISORY UNTIL 1 AM EST SUNDAY FOR VTZ013>015.
&&
$$
SYNOPSIS...IAA
NEAR TERM...IAA
SHORT TERM...IAA
LONG TERM...ELH
AVIATION...JPV
HYDROLOGY...IAA
