FXUS61 KBTV 081857
AFDBTV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
157 PM EST TUE DEC 8 2009
.SYNOPSIS...
LIGHT SNOW SHOWERS WILL BE POSSIBLE THIS MORNING...MAINLY IN THE
MOUNTAINS. ANY ACCUMULATIONS WILL BE LIGHT. AFTER A BRIEF
RESPITE...THE CHANCES FOR PRECIPITATION RETURN LATE TONIGHT AS A
STRONG STORM SYSTEM MOVES ACROSS THE MIDWEST STATES. SNOW WILL
SPREAD ACROSS THE NORTH COUNTRY FROM THE SOUTHWEST AFTER MIDNIGHT
TONIGHT...THEN BECOME HEAVY WEDNESDAY MORNING. SEVERAL INCHES OF
ACCUMULATION ARE POSSIBLE...ESPECIALLY IN EASTERN VERMONT AND THE
EASTERN PORTIONS OF THE ADIRONDACKS. SNOW WILL BECOME A MIX OF SLEET
AND RAIN WEDNESDAY AFTERNOON BEFORE CHANGING BACK TO ALL SNOW
WEDNESDAY NIGHT. STRONG GUSTY WINDS ARE EXPECTED WEDNESDAY THROUGH
THURSDAY...WITH SOME POWER OUTAGES POSSIBLE.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 905 AM EST TUESDAY...UPDATED THE FORECAST THIS MORNING TO
PROLONG MORNING SNOW SHOWERS...ESPECIALLY ACROSS THE CHAMPLAIN
VALLEY AND NORTHERN GREENS. SURFACE PRESSURE ANALYSIS BACKS UP
WHAT WE ARE SEEING ON RADAR THIS MORNING. THAT A TROUGH OF LOW
PRESSURE IS ACROSS THE MID TO NORTHERN PORTION OF THE NORTH
COUNTRY. AS THIS MOVES SOUTHEAST...WINDS ARE SHIFTING FROM SOUTH
TO NORTH...AS IF WITH A FRONTAL PASSAGE. SHOW SHOWERS HAVE ALSO
BLOSSOMED IN THE CPV AND NORTHERN GREENS WITH THIS TROUGH...AND
WILL CONTINUE THROUGH THE MORNING HOURS. PERIODS OF LOCAL AND
BRIEF MODERATE SNOWFALL HAS BEEN REPORTED WITH SOME REDUCED
VISIBILITIES. AS THE TROUGH CONTINUES TO MOVE ESE AND WEAKEN WE
WILL SEE THIS SNOW ACTIVITY QUIET DOWN...THUS ONLY UP TO AN INCH
AND A HALF OF ADDITIONAL ACCUMULATION IS GENERALLY EXPECTED
THROUGH THIS MORNING. OTHERWISE THE FORECAST IS STILL ON TRACK.
SATELLITE SHOWS SOME SIGNIFICANT CLEARING DEVELOPING IN THE ST.
LAWRENCE VALLEY AND WEST...ASSOCIATED WITH A CENTER HIGH PRESSURE
OVER ONTARIO. THIS HIGH WILL MOVE OVER THE FORECAST AREA THIS
AFTERNOON. AS SUCH...WE STILL ANTICIPATE MOSTLY CLEAR TO PARTLY
SUNNY SKIES THIS AFTERNOON. TEMPERATURES WILL BE NEAR NORMAL WITH
HIGHS EXPECTED TO TOP OUT IN THE LOWER TO MID 30S.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 444 AM EST TUESDAY...A VERY COMPLICATED FORECAST FOR THE
SHORT TERM WITH PRECIPITATION TYPE...TOTAL SNOWFALL
ACCUMULATIONS...AND GUSTY WINDS ALL MAJOR CONCERNS. THE GFS HAS
BEEN THE MOST CONSISTENT WITH THIS FEATURE AND SO WAS THE
PREFERRED SOLUTION WITH A FEW TWEAKS TO THE DETAILS. SEVERAL
HEADLINES HAVE BEEN ISSUED...AND ARE DETAILED BELOW.
FOR TONIGHT...START OUT DRY AS AFOREMENTIONED SURFACE RIDGE CRESTS
OVER THE FORECAST AREA. IT QUICKLY SHUNTS EASTWARD AS A VIGOROUS LOW
PRESSURE SYSTEM MOVES NORTHEAST ACROSS THE MIDWESTERN CONUS.
CURRENT SURFACE ANALYSIS AND OBSERVATIONS PLACE THIS FEATURE IN THE
VICINITY OF THE FOUR CORNERS WITH WIDESPREAD SNOW BEING REPORTED
FROM ILLINOIS TO COLORADO. AS THIS FEATURE MOVES TO NEAR CHICAGO BY
12Z WED SNOW WILL SPREAD OVER THE FORECAST AREA FROM SOUTHWEST TO
NORTHEAST. PRECIPITATION RATES WILL INITIALLY BE LIGHT WITH JUST A
DUSTING TO A HALF INCH EXPECTED SOUTH OF A MASSENA TO BURLINGTON TO
LEBANON LINE. SOUTH FLOW WILL INCREASE DURING THE OVERNIGHT AS
WELL...USHERING WARM AIR INTO THE REGION. STAYED CLOSE TO GFS
NUMBERS FOR OVERNIGHT TEMPERATURES AS OTHER MODELS LOOKED TOO COLD.
WEDNESDAY...WAA REALLY PICKS UP DURING THE MORNING AS THE SURFACE
LOW MOVES ACROSS THE GREAT LAKES TO NEAR GEORGIA BAY AND A SOUTHERLY
JET OF 65+ KT STREAMS INTO NEW YORK AND NEW ENGLAND. THE MID AND
UPPER LEVEL JETS WILL BE ACROSS SOUTHERN NEW ENGLAND PLACING THE
FORECAST AREA IN THE FAVORABLE LEFT FRONT QUADRANT. AS SUCH EXPECT A
BURST OF HEAVY SNOW TO AFFECT THE REGION IN THE 12Z-15Z TIME FRAME.
SEVERAL INCHES OF SNOW ARE POSSIBLE DURING THIS PERIOD.THIS IS
ESPECIALLY TRUE IN SOUTHEAST VERMONT AND THE EASTERN SLOPES OF THE
ADIRONDACKS AS STRONG SOUTHEAST WINDS RESULT IN CONSIDERABLE UPSLOPE
PRECIPITATION. THIS WIND ORIENTATION IS ALSO IDEAL FOR
DOWNSLOPING ON THE WESTERN SIDE OF THE GREENS WITH GUSTS OF 50 TO 60
MPH POSSIBLE ESPECIALLY IN THE USUAL PRONE MOUNTAIN GAPS. WINDS WILL
GRADUALLY INCREASE DURING THE MORNING HOURS AND PEAK IN THE EARLY TO
MID AFTERNOON. POWER OUTAGES WILL BE POSSIBLE AS TREES AND POWER
LINES COULD COME DOWN. HAVE THEREFORE ISSUED A HIGH WIND WATCH 12Z
WED THROUGH 00Z THU FOR THESE AREAS. AS BEST LIFT SHIFTS EAST DURING
THE LATE MORNING/EARLY AFTERNOON...PRECIPITATION RATES WILL WIND
DOWN. WITH WARM AIR CONTINUING TO STREAM IN ALOFT SNOW WILL BEGIN TO
CHANGE TO SLEET AND EVENTUALLY RAIN FROM SOUTH TO NORTH. THE EXACT
NORTHWARD EXTENT OF THE WARM LAYER AND RESULTANT MIXED PRECIPITATION
IS STILL DIFFICULT TO PINPOINT. 00Z GFS BRINGS THE 850MB 0C LINE TO
THE CANADIAN BORDER WITH 925MB TEMPS REACHING 1-3C, WHILE THE 00Z
NAM KEEPS THE FREEZING LINE AT BOTH LEVELS CONFINED TO SOUTHERN NEW
ENGLAND. THIS DISPARITY IS MAINLY DUE TO HOW THE MODELS HANDLE
SECONDARY CYCLOGENESIS. THE GFS KEEPS AN OPEN TROUGH THAT EXTENDS
INTO THE GULF OF MAINE AND DOES NOT FORM A CLOSED LOW UNTIL 12Z THU
OVER EXTREME NORTHEAST MAINE. THE 00Z NAM MEANWHILE IS MORE
AGGRESSIVE WITH COASTAL DEVELOPMENT WITH A 985MB LOW JUST OFF THE
NH/ME COAST BY 03Z THU. AS MENTIONED PREVIOUSLY...THE WARMER GFS
SOLUTION IS PREFERRED AS IT HAS BEEN MOST CONSISTENT AND THE COLDER
NAM IS AN OUTLIER. HOWEVER...DID THINK THAT THE GFS WAS TOO GENEROUS
WITH LIQUID PRECIPITATION AS IT HAD RAIN SPREAD TO NEARLY THE
INTERNATIONAL BORDER. THEREFORE TRENDED A BIT COLDER AND KEPT MORE
OF A MIX IN THE FORECAST ESPECIALLY IN THE ELEVATED VALLEYS OF
NORTHEAST VERMONT WHERE COLD AIR WILL BE MORE DIFFICULT TO SCOUR
OUT. THIS SHOULD RESULT IN A FEW MORE INCHES OF ACCUMULATING SLEET
AND SNOW IN THESE AREAS WEDNESDAY AFTERNOON AND EVENING. BY THE TIME
ALL IS SAID AND DONE...SNOWFALL AMOUNTS OF 3-5 INCHES ARE EXPECTED
IN THE CHAMPLAIN AND SAINT LAWRENCE VALLEYS...WITH 4-8 INCHES IN THE
ADIRONDACKS AND EASTERN GREENS. ACCORDINGLY...ISSUED A WINTER
WEATHER ADVISORY FOR THE VALLEYS AND A WINTER STORM WATCH FOR THE
MOUNTAINS.
WEDNESDAY NIGHT...SURFACE LOW CONTINUES ITS JOURNEY ACROSS ONTARIO
AND EVENTUALLY INTO WESTERN QUEBEC WHILE A SECONDARY LOW STARTS TO
DEVELOP OVER NORTHERN MAINE. BUFKIT PROFILES INDICATE THAT MIXED
PRECIPITATION WILL WIND DOWN AS FLOW BECOMES MORE WESTERLY AND COLD
AIR FILTERS IN ALOFT. HENCE EXPECT MAINLY JUST RAIN AND SNOW
WEDNESDAY EVENING CHANGING TO ALL SNOW AS THE BOUNDARY LAYER COOLS.
PRECIPITATION WILL BECOME MORE OROGRAPHIC IN NATURE OVERNIGHT AS
MAIN DYNAMICS SHIFT EAST AND UPSLOPE SHIFTS TO THE WESTERN SIDES OF
THE MOUNTAINS. DOWNSLOPING INTO THE CHAMPLAIN VALLEY WILL PREVENT
MUCH MORE ADDITIONAL ACCUMULATION THERE. WINDS...WHILE CHANGING
DIRECTION...WILL REMAIN GUSTY AND SCATTERED POWER OUTAGES WILL
CONTINUE TO BE POSSIBLE.
THURSDAY...LOW PRESSURE WILL CONTINUE TO PULL AWAY FROM VERMONT AND
NORTHERN NEW YORK THURSDAY. SNOW SHOWERS WILL ALSO CONTINUE AS THE
UPPER TROUGH SPINS OVER THE REGION. IN ADDITION...LAKE EFFECT SNOW
WILL DEVELOP OFF OF LAKE ONTARIO AND SPREAD INTO THE ADIRONDACKS AND
ALONG THE SOUTHERN GREENS IN STRONG WEST FLOW. SCATTERED WIND DAMAGE
WILL ALSO CONTINUE TO BE POSSIBLE WITH GUSTS OF 40+ MPH EXPECTED.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 157 PM EST TUESDAY...ON BACKSIDE OF EXITING SYSTEM FOR FRIDAY...
CWA WILL BE UNDER WNW FLOW ALLOWING FOR PERSISTENT -SW WHICH WILL
TAPER OFF FROM W TO E AS LOW PRESSURE SYSTEM HEADS INTO THE
CANADIAN MARITIMES. W/ SFC RIDGE SETTING UP OVER THE MID-ATLANTIC
REGION...FRI NGT INTO SAT WILL HAVE WINDS SHIFT TO MORE
WESTERLY...ALLOWING FOR LK EFFECT SNOW POTENTIAL ESPECIALLY FOR N
NY NEAR LK ONTARIO. RIDGE DOES BUILD N INTO THE REGION SAT NGT
INTO SUNDAY FOR A NICE CD DAY FOR THE CWA. HAVE KEPT FAIRLY
CONSISTENT HIGHS/LOWS FOR ENITRE CWA BASED ON WIND REGIME. 850
TEMPS DURING THIS TIMEFRAME VARY VERY SLIGHTLY. NEXT SF CLOW TO
AFFECT THE NORTH COUNTRY WILL BUILD ACROSS THE CWA BY SUN AFTNOON.
EXPECTING QPF TO BE LGT BASED ON SFC LOW TRACK TO THE N...BUT WITH
CD POOL OF 850 TEMPS DROPPING DOWN TO -22C/-26C BY EVENING FROM
DAY HIGHS NEAR -8C. POTENTIAL FOR SNOW SQUALLS/FLASH FREEZE AS
THIS PUSHES E...ESPECIALLY FOR NORTHERN PORTIONS OF THE CWA. W/
THIS FROPA...WINDS SHIFT TO THE NNW ALLOWING FOR LEFTOVER UPSLOPE
-SW MONDAY MORNING...CLRING BY MDDAY AS HIGH PRESSURE BUILDS E
OVER THE AREA AND REMAINING INTO TUESDAY.
&&
.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
THROUGH 18Z WEDNESDAY...SCT VFR LL CLD COVER WILL GIVE WAY TO SCT-
BKN120 AHEAD OF NEXT WX SYSTEM. THIS MID/HIGH CLD COVER WILL WORK
NE INTO THE AREA BY 00Z WED. BY 06Z WED MORE LOW CLDS WORK NE AND
EVENTUALLY LEAD TO CEILINGS LWRING FROM VFR DOWN TO LFR/LIFR AS
LGT SNOW DEVELOPS THRU 11Z. DURING THIS TIME VSBY VARYING FROM
2-5SM. HEAVIER BURST OF SNOW AFT 11Z-12Z THAT WILL BRING VSBY DOWN
TO LESS THAN 1SM AT TIMES THRU 16Z. SFC SYSTEM WILL BEGIN TO SHIFT
HEAVIEST PRECIP N OF THE AREA BY 16Z SO WILL TREND INCR VSBY. SOME
WARM AIR ALOFT WILL ALSO HELP TO SLACKEN PRECIP. WINDS WILL BE
OTHER ISSUE DURING LATTER HALF OF FORECAST PERIOD. STRONG JET
ALOFT WILL BRING SUSTAINED WINDS 15-30KTS FROM MAINLY FROM THE SSE
(ENE-ESE IN N NY). WINDS SHEAR 45-55KTS POSSIBLE FROM 09Z-
14Z...ESPECIALLY OVER RUT/MPV/SLK.
18Z WEDNESDAY THROUGH SATURDAY...MODERATE TO BRIEFLY HEAVY SNOW IS
EXPECTED 12-18Z WEDNESDAY...FOLLOWED BY A MIX OF SLEET AND RAIN
BEFORE STEADY PCPN ABATES TOWARD EVENING WITH LINGERING AREAS OF
DRIZZLE. WINDS SHIFT INTO THE WEST WEDNESDAY NIGHT ALLOWING FOR
SCATTERED SNOW SHOWER ACTIVITY AS COLDER AIR WORKS BACK INTO THE
REGION. GUSTY SELY WIND CONDITIONS ARE ALSO EXPECTED MUCH OF WED
AND WED NIGHT...ESPECIALLY AT KRUT...WITH SELY GUSTS 40+KT POSSIBLE.
LOW PRES DEPARTS TO THE NORTH ON THURSDAY WITH STRONG WEST WINDS
DEVELOPING 15-25 KT WITH GUSTS 30 KT AND SCATTERED SNOW SHOWER
ACTIVITY PRODUCING LOCALIZED IFR CONDITIONS. A FEW SNOW SHOWERS
MAY LINGER INTO FRIDAY. VFR ON SATURDAY...AS A RIDGE OF HIGH
PRESSURE BUILDS BACK INTO THE REGION.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...WINTER STORM WATCH FROM LATE TONIGHT THROUGH WEDNESDAY EVENING
FOR VTZ003-004-006>008-010-012-019.
WINTER WEATHER ADVISORY FROM 4 AM TO 10 PM EST WEDNESDAY FOR
VTZ001-002-005-009-011-016>018.
HIGH WIND WATCH FROM WEDNESDAY MORNING THROUGH WEDNESDAY
EVENING FOR VTZ016>019.
NY...WINTER STORM WATCH FROM LATE TONIGHT THROUGH WEDNESDAY EVENING
FOR NYZ029>031-034.
WINTER WEATHER ADVISORY FROM 4 AM TO 10 PM EST WEDNESDAY FOR
NYZ026>028-035-087.
&&
$$
SYNOPSIS...MB
NEAR TERM...MB
SHORT TERM...AMF/MB
LONG TERM...JN
AVIATION...BANACOS/JN
