FXUS61 KBTV 091145
AFDBTV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
645 AM EST WED DEC 9 2009
.SYNOPSIS...
A STRONG STORM SYSTEM WILL BRING A VARIETY OF WINTRY WEATHER TO
THE REGION TODAY INTO THIS EVENING...WITH SNOW...MIXED
PRECIPITATION AND GUSTY WINDS EXPECTED. PRECIPITATION WILL TAKE
ON A MORE SHOWERY CHARACTER BY LATER TONIGHT AS A STRONG COLD
FRONT SWEEPS EASTWARD ACROSS THE AREA. BEHIND THIS FRONT GUSTY
WEST WINDS ARE EXPECTED THURSDAY INTO FRIDAY ALONG WITH SCATTERED
TO NUMEROUS SNOW SHOWERS...ESPECIALLY ACROSS THE MOUNTAINS AND
LAKE ONTARIO SNOWBELTS.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 247 AM EST WEDNESDAY...VERY COMPLEX AND CHALLENGING FCST
TAKING SHAPE FOR TODAY AS DEEP LOW PRESSURE TRACKS THROUGH THE
GREAT LAKES STATES DRIVING LARGE SCALE ASCENT NORTHEASTWARD
ACROSS OUR AREA. IMPRESSIVE DYNAMICAL SETUP WITH VERY STRONG
WAA/ISENTROPICALLY DRIVEN QPF EXPECTED IN MOST AREAS.
HOWEVER...ADDING COMPLEXITY TO OVERALL SITUATION WILL BE DEGREE
OF LOW TO MID LVL WARMING THAT OCCURS AT MID LVLS (925-850 MB)
LATER THIS AFTERNOON AS PCPN SHIELD PUSHES NORTHEASTWARD AND
DEGREE TO WHICH VERY STRONG SERLY WIND FIELDS INFLUENCE INTENSITY
AND AMOUNTS OF PCPN. I'M LEANING CLOSER TO NAM/4KM WRF SOLNS HERE
AS THESE MODELS APPEAR TO HAVE BEST HANDLE ON EVOLUTION OF LOW TO
MID LVL THERMAL PROFILES. THEREFORE...PCPN SHOULD START AS SNOW
AND COME IN VERY QUICKLY FROM SW TO NE DURING THE EARLY TO MID
MORNING HOURS...WHICH WILL LIKELY CAUSE CONSIDERABLE HEADACHES
DURING THE MORNING COMMUTE. WITH SUCH STRONG SERLY FLOW AT MID
LVLS...WILL HIGHLIGHT HEAVIEST QPF ON THE WINDWARD...IN THIS CASE
EASTERN SLOPES OF OUR DACKS/GREENS WHERE FLOW IS FORCED SHARPLY
UPWARD. CONSIDERABLY LESS QPF EXPECTED IN CHVLY AND WESTERN SLOPES
OF THE NRN GREENS WHERE STRONG COMPRESSIONAL DOWNSLOPING
SIGNATURE QUITE EVIDENT ON THIS MORNING'S 00Z 4KM WRF RUN. AS
WARM NOSE SURGES NORTHWARD LATER TODAY...PCPN LIKELY TO TAKE ON A
MIXED CHARACTER BEFORE TAPERING OFF IN INTENSITY TOWARD
EVENING...ESP ACROSS SWRN VT AND INTO THE WRN DACKS/SRN SLV AS
PRONOUNCED DRY SLOT PUSHES EASTWARD. ELSEWHERE...PROFILES MORE
CONFLICTING AND GIVEN THAT MANY AREAS OF ERN VT ARE GETTING OFF
TO A COLD START...MUCH OF THE QPF TODAY WILL LIKELY FALL AS SNOW.
AFTER RUNNING SEVERAL ALGORITHMS...SNOW TOTALS END UP FAIRLY
SIMILAR TO PRIOR FCST SHOWING GENERAL 4-8 INCH AMOUNTS ACROSS THE
ERN SLOPES OF THE GREENS...3-6 INCHES IN THE ST LAWRENCE AND
CHAMPLAIN VALLEYS...AND 5 TO 10 INCHES IN THE DACKS. HIGH TEMPS
ALSO TRICKY HERE...BUT GENERALLY EXPECTING VALUES IN THE L-M30S
BY LATER IN THE DAY...WITH SLIGHTLY COOLER READINGS ACROSS NERN
VT.
NOW FOR THE WINDS. PERUSAL OF LATEST BNDRY LYR SOUNDING PROFILES
THIS MORNING HAS ME QUITE CONCERNED FOR AREAS ALONG THE WESTERN
SLOPES OF OUR GREEN MOUNTAINS...ESP IN ADDISON AND RUTLAND
COUNTIES. WITH LATEST WRF RUN SHOWING SERLY FLOW OF 60-70 KTS
BELOW 2 KFT IN THESE AREAS...COULD EASILY SEE GUSTS TO 60 MPH OR
EVEN A TAD STRONGER FROM DANBY TO NORTH CLARENDON...NORTH INTO
THE EASTERN SIDE OF RUTLAND CITY...RIPTON AND LINCOLN. BASED OFF
THIS LATEST INFORMATION...WILL MAINTAIN HIGH WIND WARNINGS AS IS
THOUGH ADD WESTERN RUTLAND AND LAMOILLE COUNTIES WITH POWER
OUTAGES AND TREE DAMAGE LIKELY IN THESE LOCALES. BEST ESTIMATE
FOR TIMING OF STRONGEST WINDS WOULD BE FROM 14Z-22Z TODAY.
ELSEWHERE...GUSTY TO OCCASIONALLY STRONG WINDS ALSO POSSIBLE
ALONG THE WESTERN SLOPES OF THE DACKS IN NRN NY AND TO THE LEE OF
WHITE MOUNTAINS AND INTO THE HIGHER ELEVATIONS OF NERN VT.
HOWEVER...WITH WINTER STORM WARNINGS IN EFFECT FOR THESE AREAS
AND OWING TO THE FACT THAT MAGNITUDE OF GUSTS LIKELY A TAD
LESS...WILL MINIMIZE COMPLEXITY HERE AND KEEP DISCRETE MENTION OF
THESE WINDS IN THE WINTER WEATHER STATEMENTS FOR THESE AREAS.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
AS OF 247 AM EST WEDNESDAY...BY TONIGHT BEST FORCING PUSHES NORTH
AND EAST OF THE REGION AS DRY SLOT CONTINUES TO PUSH EASTWARD
ACROSS THE CENTRAL/SRN PORTIONS OF THE FCST AREA. THEREFORE PCPN
WILL TAKE ON A MORE DRIZZLY/SHOWERY CHARACTER AS TEMPS HOLD
STEADY OR SLOWLY RISE THROUGH THE EVENING HOURS. WILL MAINTAIN
DECENT CHC TO LIKELY POPS HERE...BUT AGAIN ADDL PCPN WILL BE MUCH
LIGHTER. STRONG SFC COLD FRONT THEN PUSHES WEST TO EAST ACROSS
THE AREA LATER AT NIGHT WITH FLOW VEERING FROM SOUTH TO
WEST/SOUTHWEST AND CAA BEGINNING IN EARNEST. WILL OFFER A BLEND
OF MOS GUIDANCE FOR MINS HERE WITH AGAIN TEMPS HOLDING STEADY
THROUGH THE EVENING...THEN FALLING DURING THE LATER OVERNIGHT
HOURS TOWARD MORNING.
THEREAFTER...PRIMARY WEATHER WILL FEATURE MORE GUSTY WINDS AND
SCT/NUMEROUS MTN/LK EFFECT SHSN. POST-FRONTAL WESTERLY FLOW
LIKELY TO BE QUITE GUSTY DURING THURSDAY WITH GUST SPEEDS EASILY
ECLIPSING 35 MPH...ESP IN FAVORED AREAS OF THE SLV AND CT RVR
VALLEY WHICH TEND TO SEE HIGHER SPEEDS IN THESE REGIMES. AS MEAN
925-850 MB TEMPS FALL SHARPLY DURING THE DAY...LAKE EFFECT AND
OROGRAPHICALLY ENHANCED SHSN SHOULD BLOSSOM CONSIDERABLY WITH
ADDL ACCUM LIKELY...ESP IN THE LK ONTARIO SNOWBELTS OF SRN ST
LAWRENCE/SRN FRANKLIN COUNTIES. TEMPS REALLY GOING NOWHERE AND
WILL HIGHLIGHT READINGS ONLY A TAD ABOVE PRIOR NIGHT'S MINS IN
THE GRIDDED DATASET.
BY THURSDAY NIGHT INTO FRIDAY WINDS SLOWLY ABATE THOUGH WITH
P-GRAD REMAINING FAIRLY TIGHT...CONDS STILL LIKELY TO BE BREEZY
IN MANY AREAS. OF MORE CERTAINTY WILL BE THE CONTINUATION OF LK
EFFECT AND MTN SHSN WHERE ADDL ACCUM LIKELY TO THE LEE OF LK
ONTARIO WHERE FUTURE HEADLINES MAY BE NEEDED. TEMPS WILL RUN ON
THE CHILLY SIDE WITH LOWS 14 TO 22 AND HIGHS 18 TO 26.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 157 PM EST TUESDAY...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 ENTIRE CWA BASED ON WIND REGIME. 850
TEMPS DURING THIS TIMEFRAME VARY VERY SLIGHTLY. NEXT SFC LOW 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 /12Z WEDNESDAY THROUGH SUNDAY/...
THROUGH 12Z THURSDAY...SN HAS DEVELOPED ACRS THE REGION AND WILL
CONTINUE TO SPREAD FROM SW TO NE ACROSS THE AREA. CONDS WILL BE
LOWERING RAPIDLY TO IFR/LIFR...WITH PERIODS OF MOD TO HVY SN FROM
13Z-20Z. WARMER AIR MOVING IN ALOFT AT 925 MB WILL CHANGE THE SN
OVER TO SLEET...OR A MIX OF SNOW AND SLEET AFT 18Z...AND THEN
CHANGING TO RN IN THE 20Z-21Z TIME RANGE. MODEL GUIDANCE SUGGESTS
BELOW FREEZING TEMPS AT THE SFC COULD PERSIST ACRS THE ST
LAWRENCE VALLEY AND ESTRN VT THRU 00Z THU...SO SOME AREAS COULD
POTENTIALLY SEE SOME FRZ RA. HOWEVER...CONFIDENCE IS LOW AT THIS
TIME FOR FRZ RA. STILL HAVE SOME UNCERTAINTY AS TO THE EXACT
TIMING OF WHEN SN WILL CHANGE TO SLEET AND RA THIS
AFTERNOON...BUT LOOKS LIKE IT WILL BE AROUND 20Z. WRF MODEL
CONTINUES TO SHOW DRY SLOT WORKING INTO THE AREA...ESPECIALLY
ACROSS VT...BY ABOUT 02Z OR 03Z. LATEST MODEL GUIDANCE ALSO
SHOWING STRONG SOUTHEAST WINDS ALOFT...SO GOOD POTENTIAL FOR LOW
LEVEL WIND SHEAR TO DEVELOP ACROSS THE REGION AFTER 12Z TODAY AND
CONTINUE THROUGH 00Z THURSDAY. HAVE INDICATED DRY SLOT MOVING
INTO THE REGION AROUND 02Z OR 03Z...BUT CIGS SHOULD REMAIN LOW
WITH SOME BR AS WELL. AFTER ABOUT 06Z THE WINDS WILL SHIFT FROM
SOUTHEAST TO SOUTHWEST...AND REMAIN GUSTY. SCATTERED SNOW SHOWERS
WILL CONTINUE AS COLD AIR WORKS BACK INTO THE REGION. BECAUSE OF
THE SCATTERED NATURE OF THESE SNOW SHOWERS...HAVE NOT INCLUDED
MENTION OF SN AT TERMINALS AT THIS TIME. GUSTY WINDS ARE EXPECTED
THROUGH THE NIGHT...ESPECIALLY AT RUT WITH GUSTS 40+KT POSSIBLE.
12Z THURSDAY THROUGH SUNDAY...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 UNTIL 10 PM EST THIS EVENING FOR VTZ003-
004-006>008-010-012-018-019.
WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR
VTZ001-002-005-009-011-016-017.
HIGH WIND WARNING UNTIL 7 PM EST THIS EVENING FOR VTZ006-011-
016>019.
NY...WINTER STORM WARNING UNTIL 10 PM EST THIS EVENING FOR
NYZ029>031-034.
WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR
NYZ026>028-035-087.
&&
$$
SYNOPSIS...JMG
NEAR TERM...JMG
SHORT TERM...JMG
LONG TERM...JN
AVIATION...WGH/NEILES
