FXUS61 KBTV 090157
AFDBTV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
857 PM EST TUE DEC 8 2009
.SYNOPSIS...
A STRONG STORM SYSTEM WILL BRING A WIDE VARIETY OF WEATHER TO THE
NORTH COUNTRY WEDNESDAY THROUGH FRIDAY. WEDNESDAY WILL FEATURE
HEAVY SNOW...ESPECIALLY DURING THE FIRST HALF OF THE DAY BEFORE
BECOMING A MIX OF PRECIPITATION. STRONG WINDS WILL ALSO AFFECT THE
GREEN MOUNTAINS. STRONG GUSTY WINDS ALONG WITH SNOW SHOWERS WILL
IMPACT THE ENTIRE REGION WEDNESDAY NIGHT THROUGH FRIDAY. TRAVEL
WILL BE DIFFICULT...AND SCATTERED POWER OUTAGES ARE POSSIBLE.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
AS OF 857 PM EST TUESDAY...QUICK UPDATE TO THIS EVENING'S
PACKAGE...MAINLY TO REFLECT COOLER OVERNIGHT MINS. INITIAL CLEARING
SKIES ALONG WITH FRESH ALBEIT LIGHT SNOW COVER FROM YESTERDAY HAS
ALLOWED TEMPS TO FALL QUICKLY THIS EVENING...WELL DOWN INTO THE
TEENS IN MANY SPOTS ACROSS THE NORTHERN HALF OF THE FCST AREA. STILL
EXPECTING CLOUDS/WINDS TO INCREASE OVERNIGHT AS BROAD-SCALE DYNAMICS
AND SNOW SHIELD PUSH NORTHEAST. THIS SHOULD CAUSE TEMPS TO BEGIN A
SLOW RISE AFTER MIDNIGHT THOUGH STILL REMAIN BELOW FREEZING...SO
PCPN WILL START AS SNOW IN ALL AREAS BY SUNRISE OR SHORTLY
THEREAFTER. MORNING COMMUTE ON WEDNESDAY WILL LIKELY BECOME QUITE
NASTY...ESP AFTER 7 AM SO LEAVING EARLY FOR WORK MAY BE A GOOD
PLAN...ESP FROM BTV-PBG SOUTH AND WEST. HAVE A GOOD EVENING.
PREVIOUS DISCUSSION...
SORRY FOR THE DELAY IN GETTING THIS
OUT. NOT AN EASY FORECAST BY ANY STRETCH OF THE IMAGINATION AND
LOTS OF ITEMS TO CONSIDER. SO I'LL GET RIGHT TO IT.
TONIGHT...FAIRLY QUIET. CLOUDS INCREASE LATE. TEMPS WILL NOSEDIVE
EARLY THIS EVENING...AND THEN AFTER MIDNIGHT BEGIN TO INCREASE.
NO BIG CHANGES TO MODEL GUIDANCE BUT A FEW SUBTLE ITEMS HAVE
CHANGED...AND THOSE SUBTLE THINGS DO HAVE BIG IMPACTS. STILL
FOLLOWING GFS SD NAM SEEMS TO BE OVERLY AGRESSIVE WITH
REDEVELOPMENT ALONG THE COAST TOMORROW. GFS HAS TRENDED A BIT
COLDER WHICH HAS BIG IMPLICATIONS ON PRECIP FORECAST AND SNOW
AMOUNTS. GIVEN TODAY HAS BEEN RUNNING COOLER THAN EARLIER GUIDANCE
AND SOME CHILLY TEMPS AND LOW DEWPOINTS JUST TO OUR NORTH...IT'S
PRUDENT TO FOLLOW THE COLDER TREND. VERY IMPRESSIVE DYNAMICS --
BOTH THERMAL AND JET VARIETY -- WILL RAPIDLY DEVELOP ACROSS THE
REGION LATE TONITE. EXPECT BURST OF WARM AIR ADVECTIONS SNOWS TO
RAPIDLY DEVELOP FROM SW TO NE AFTER 06Z. TOMORROWS MORNING DRIVE
WILL BE A MESS. SEVERAL INCHES ALREADY ON THE GROUND AND SNOWFALL
RATES OF 1"/HR OR MORE. IMPRESSIVE 850MB JET OF 66-85KTS WILL
BRING WARMER AIR IN ALOFT...BUT IT WONT BE UNTIL EARLY AFTERNOON.
BY THAT TIME THE BULK OF THE PRECIP WILL BE OVER WITH. STILL
EXPECTING A MIX OF RAIN/FREEZING RAIN/SLEET FOR MANY AREAS AT SOME
POINT. THE GRIDDED FORECAST DATABASE IS A MESS BECAUSE OF IT.
WITH SLIGHTLY COLDER SCENARIO...HAVE BUMPED SNOWFALL ACCUMLATIONS
UP A COUPLE OF INCHES. THIS HAS REQUIRED ISSUANCES OF WINTER STORM
WARNINGS AND CONTINUATION OF ADVISORIES.
HOW MUCH SNOW WILL FALL IS STILL A TOUGH QUESTION AND FORECAST IS
RATHER LOW CONFIDENCE. MODELS CAME IN WITH HIGHER QPF...ON ORDER
OF 1 TO 1.5" THRU 00Z THURSDAY. THAT IS A BIT DISCONCERTING AND
WOULD MEAN WELL OVER A FOOT OF SNOW IN MANY LOCATIONS. FEEL THAT
MODELS ARE BIT TOO AGRESSIVE AND CUT BACK TO 0.60 TO 0.75IN QPF.
HOWEVER ADDED IN OROGRAPHIC EFFECTS WHICH WILL BE
CONSIDERABLE...AND THE RANGE GOES FROM 0.3 INCHES IN SHADOWED
LOCATIONS DOWNWIND OF ADIRONDACKS...GREEN AND WHITE MOUNTAINS.
HOWEVER QPF GOES UP TO ABOUT 1IN IN FAVORED UPSLOPE REGIONS OF ERN
GREENS AND DACKS.
NET RESULT IS 6 TO 10 INCHES IN SOUTH CENTRAL VT TO PERHAPS A FOOT
ON EASTERN SIDE OF ADIRONDACKS...AND 3 TO 5 INCHES IN THE
VALLEYS/NE VERMONT. HOWEVER...IF THE MODELS ARE CORRECT THIS
FORECAST IS UNDERPLAYING TOTAL SNOW. OR IF WARMER AIR GETS IN TOO
QUICKLY...THEN THE FORECAST IS OVERPLAYING TOTAL SNOW. I THINK YOU
GET THE PICTURE.
OTHER BIG PROBLEM WILL BE WINDS ALONG THE SPINE AND WESTERN SLOPES
OF THE GREENS. HAVE THOSE STRONG WINDS ALOFT...TUCKED UNDER THE
INVESION ALOFT AND JUST ABOVE SUMMIT HEIGHT. THATS A GOOD RECIPIE
FOR BREAKING WAVES IN THE ATMOSPHERE AND STRONG DOWNSLOPE WINDS.
THINKING 60MPH GUSTS NOT OUT OF THE QUESTION. HAVE GONE HIGH WIND
WARNING FOR THE SPINE...BUT THREW IN WIND ADVISORY FOR A FEW
NEARBY AREAS THAT ALSO GET HIT WITH SUCH WINDS...NAMELY RUTLAND
AREA AND WESTERN LAMOILLE COUNTY.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
AS OF 350 PM EST TUESDAY...THE BIG STORY FOR THE PERIOD WILL BE
WIND...WIND...WIND AND SOME PERSISTANT LAKE EFFECT BANDS AND SNOW
SHOWERS. STRONG LOW PRESSURE WILL BE MOVING NORTH OF US ACROSS
QUEBEC BUT NOT ALL THAT FAST. REGION STAYS IN TIGHT PRESSURE
GRADIENT. WITH COLD AIR ADVECTION LEADING TO EXCELLENT
MIXING...WE'LL BE TAPPING INTO A LOT OF STRONG WINDS AREA WIDE.
SUSPECT WIND ADVISORY WILL BE NEEDED FOR THE ENTIRE REGION BUT
LETS GET THRU THE STUFF TOMORROW FIRST. PER BUFKIT SOUNDING
ANALYSIS...ENTIRE REGION SHOULD SEE FREQUENT GUSTS OF 35 TO 45 MPH
FROM LATE WEDNESDAY NIGHT ALL THE WAY INTO FRIDAY. THIS WILL
LIKELY LEAD TO ADDITIONAL POWER OUTAGES AND DOWNED TREES.
WINDS AND INSTABILITY WILL LINE UP TO PRODUCE A LONG LASTING SEMI-
PERMANENT LAKE EFFECT SNOW PLUME OFF OF LAKE ERIE THURSDAY. THIS
SHOULD BE ORIENTED TOWARD THE EAST/EAST NORTHEAST. WE COULD SEE
SOME HEFTY ACCUMULATIONS ACROSS EXTREME SOUTHERN ST LAWRENCE AND
FRANKLIN COUNTIES. LAKE PLUME SHOULD ALSO MAKE IT ACROSS ESSEX
CNTY NY AND INTO VERMONT...PROBABLY ADDISON COUNTY. SUSPECT WE
WILL NEED SOME WINTER STORM WARNINGS/ADVISORIES FOR THAT FEATURE.
BUT AGAIN...LETS GET THRU THE FIRST PART OF THE STORM FIRST.
HAVENT TALKED AT ALL ABOUT TEMPS. FOLLOWED GUIDANCE WITH THIS.
TEMPS WILL FALL TO BELOW NORMAL LEVELS FOR THURSDAY AS 850MB TEMPS
CONTINUE TO COOL TO -10 TO -12C LEVELS.
&&
.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 /02Z WEDNESDAY THROUGH SUNDAY/...
THROUGH 00Z THURSDAY...CLOUDS WILL BE ON THE INCREASE OVERNIGHT...
WITH
CEILINGS LOWERING. EXPECTING VFR CONDITIONS THROUGH 10Z WEDNESDAY.
SNOW WILL DEVELOP ACROSS THE REGION BETWEEN 09Z-11Z WEDNESDAY WITH
CONDITIONS
LOWERING RAPIDLY TO IFR/LIFR...WITH PERIODS OF MODERATE TO HEAVY SNOW
FROM 13Z-20Z. WARMER AIR MOVING IN ALOFT AT 925 MILLIBARS WILL
CHANGE THE SNOW OVER TO SLEET...OR A MIX OF SNOW AND SLEET AFTER
18Z WEDNESDAY...AND THEN CHANGING TO RAIN IN THE 20Z-21Z TIME
RANGE. MODEL GUIDANCE SUGGESTING BELOW FREEZING TEMPERATURES AT
THE SURFACE COULD PERSIST ACROSS THE SAINT LAWRENCE VALLY OF
NORTHERN NEW YORK AND EASTERN VERMONT THROUGH 00Z THURSDAY...SO
SOME AREAS COULD POTENTIALLY SEE SOME FREEZING RAIN. HOWEVER...
CONFIDENCE
IS LOW AT THIS TIME FOR FREEZING RAIN. STILL HAVE SOME UNCERTAINTY
AS TO THE EXACT TIMING OF WHEN SNOW WILL CHANGE TO SLEET AND RAIN
WEDNESDAY AFTERNOON...BUT LOOKS LIKE IT WILL BE AROUND 20Z. LATEST
MODEL
GUIDANCE ALSO SHOWING STRONG SOUTHEAST WINDS ALOFT...SO GOOD
POTENTIAL FOR LOW LEVEL WIND SHEAR TO DEVELOP ACROSS THE REGION
AFTER 12Z WEDNESDAY AND CONTINUE THROUGH 00Z THURSDAY.
00Z THURSDAY THROUGH SUNDAY...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 AND MOST OF SUNDAY...AS A RIDGE OF HIGH PRESSURE BUILDS BACK
INTO THE REGION. AREAS OF MVFR IN SCATTERED SNOW SHOWERS ACROSS
NORTHERN NEW YORK LATE SUNDAY AFTERNOON.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...WINTER STORM WARNING FROM 4 AM TO 10 PM EST WEDNESDAY FOR
VTZ004-006>008-010-012-019.
WINTER WEATHER ADVISORY FROM 4 AM TO 10 PM EST WEDNESDAY FOR
VTZ001>003-005-009-011-016>018.
HIGH WIND WARNING FROM 7 AM TO 7 PM EST WEDNESDAY FOR
VTZ016>019.
WIND ADVISORY FROM 7 AM TO 7 PM EST WEDNESDAY FOR VTZ006-011.
NY...WINTER STORM WARNING FROM 4 AM TO 10 PM EST WEDNESDAY FOR
NYZ029>031-034.
WINTER WEATHER ADVISORY FROM 4 AM TO 10 PM EST WEDNESDAY FOR
NYZ026>028-035-087.
&&
$$
SYNOPSIS...NASH
NEAR TERM...JMG/NASH
SHORT TERM...NASH
LONG TERM...JN
AVIATION...WGH/JN
