FXUS61 KBTV 080255
AFDBTV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
955 PM EST MON DEC 7 2009
.SYNOPSIS...
WEAK LOW PRESSURE TRACKING ACROSS THE OHIO VALLEY INTO NEW ENGLAND
WILL PRODUCE SOME LIGHT SNOW THROUGH MIDNIGHT TONIGHT ACROSS THE
REGION. MEANWHILE...HIGH PRESSURE WILL PROVIDE THE REGION WITH
PARTLY CLOUDY SKIES ON TUESDAY WITH NEAR NORMAL TEMPERATURES. A FEW
MOUNTAIN SNOW SHOWERS WILL BE POSSIBLE. ON WEDNESDAY A STRONG STORM
SYSTEM WILL PRODUCE A WINTRY MIXTURE OF PRECIPITATION ACROSS THE
NORTH COUNTRY...ALONG WITH SOME GUSTY WINDS. TEMPERATURES WILL
MAINLY BE IN THE UPPER 20S TO MID 30S ON WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
AS OF 955 PM EST MONDAY...GOING FORECAST IN GREAT SHAPE WITH ONLY
A FEW MINOR TWEAKS FOR THIS EVENINGS UPDATE. LATEST RADAR/SATELLITE/OBS
INDICATE ONGOING SNOW SHOWERS ACROSS THE REGION THIS EVENING...THOUGH
ARE BECOMING MORE SCATTERED IN NATURE. EXPECT SNOW SHOWERS TO CONTINUE
TO DECREASE IN AREAL COVERAGE AFTER MIDNIGHT...WHICH IS ALREADY
COVERED WELL IN PREVIOUS FORECAST. REALLY NO SPOTTER REPORTS OF
ACCUMULATED SNOWFALL AROUND THE REGION EXCEPT FOR AT BTV WHERE WE
HAVE PICKED UP ONLY A FEW TENTHS. APPLYING THIS RATIO ACROSS THE
REGION WOULD ONLY RESULT IN SNOWFALL AMOUNTS OF UP TO 1 INCH
AREA-WIDE...SO HAVE DECREASED PREVIOUS FORECAST SNOW AMOUNTS.
OTHERWISE...TEMPS/WINDS/SKY ON TRACK SO NO CHANGES THERE.
PREVIOUS DISCUSSION FROM 300 PM...WATER VAPOR SHOWS A FAST PROGRESSIVE
WEST TO EAST FLW ACRS THE CONUS WITH SEVERAL EMBEDDED VORTS. FIRST
POTENT VORT ACRS CENTRAL NY ATTM...IS COMBINING WITH FAVORABLE
ULVL JET DYNAMICS AND SOME LAKE MOISTURE INTERACTION TO PRODUCE A
BAND OF SNOW ACRS OUR CWA. THIS SNOW WL CONT ACRS THE REGION THRU
03Z...BEFORE BEST 1000-700MB UVVS AND BEST ULVL DIVERGENCE MOVES
INTO EASTERN NEW ENGLAND. WL CONT TO MENTION LIKELY TO CAT POPS
THRU 03Z FOR CENTRAL/NORTHERN ZNS...WITH TOTAL SNOW ACCUMULATIONS
OF 1 TO 3 INCHES EXPECTED...BUT ISOLATED AMOUNTS OF 4 OR 5 INCHES
POSSIBLE ACRS SOUTHERN SAINT LAWRENCE COUNTY AND NORTHERN GREEN
MTNS NEAR JAY PEAK. TEMPS WL BE TRICKY BASED ON CLOUDS AND
LEFTOVER 1000-700MB MOISTURE...THEREFORE WL MENTION LOWS MAINLY IN
THE 20S. IF A FEW LOCATIONS BECM MAINLY CLR...TEMPS WITH NEW SNOW
COVER WL QUICKLY DROP INTO THE TEENS.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
AS OF 300 PM EST MONDAY...ON TUESDAY...SFC RIDGE LOCATED OVER THE OHIO
VALLEY WL MOVE ACRS OUR CWA. SOUNDINGS AND MOISTURE CROSS
SECTIONS SHOW PLENTY OF SHALLOW MOISTURE BTWN SFC AND 800MB
TUES...ESPECIALLY ACRS OUR MTNS ZNS...THEREFORE WL MENTION SCHC
POPS FOR SNOW SHOWERS THRU 18Z...THEN CLRING. NOT EXPECTING MUCH
ACCUMULATION. OTHERWISE...2M TEMPS SUPPORT HIGHS IN THE MID/UPPER
20S MTNS TO L/M 30S VALLEYS. TUESDAY NIGHT...TEMPS WL QUICKLY DROP
EARLY ACRS OUR CWA WITH MAINLY CLR SKIES...BUT SOUNDINGS SHOW
INCREASE MID/UPPER LVL MOISTURE AFT 06Z...ALONG WITH DEVELOPING
SOUTH TO SOUTHEAST WINDS...WHICH WL RESULT IN TEMPS WARMING TWD
DAYBREAK. IN ADDITION...FEEL WAA SNOW WL BE APPROACHING OUR
EXTREME SW ZNS BY DAYBREAK...THEREFORE WL CONT TO MENTION CHC
POPS. COLDEST OVERNIGHT LOWS WL BE NEK WITH READINGS IN THE TEENS.
WEDNESDAY-WEDNESDAY...THE MAIN CHALLENGES WL BE PTYPE/AMOUNT...ALONG
WITH POTENTIAL FOR HIGH WINDS. LATEST GUIDANCE IN VERY GOOD
AGREEMENT WITH POSITION OF DEEP MID/UPPER LVL TROF ACRS THE CENTRAL
PLAINS AND DEVELOPMENT OF STRONG SFC LOW PRES NEAR CHICAGO BY 12Z
WEDS. LATEST TRACK SHOWS SYSTEM LIFTING NE INTO CENTRAL
MICHIGAN...THEN INTO THE SOUTHERN OTTAWA VALLEY BY 12Z THURS...AS
SECONDARY COASTAL LOW DEVELOPS ON THE TRIPLE POINT NEAR WASHINGTON
DC. THIS DEVELOPMENT ADDS SOME COMPLICATIONS TO FCST...WITH REGARDS
TO HOW MUCH WARM AIR ADVECTS INTO OUR FA AHEAD OF THIS SYSTEM AND
EXACT PRESSURE GRADIENT BTWN THE TWO SYSTEMS. LOCAL TRRN AND
EXPECTED STORM TRACK WL HAVE A MAJOR ROLE ON PRECIP TYPE...WIND
MAGNITUDE...AND OVERALL QPF AMOUNTS.
FEEL OUR CWA WL HAVE 2 POTENTIAL WIND EVENTS WITH THIS UPCOMING
SYSTEM...FIRST WL BE SE DOWNSLOPING WINDS ALONG THE WESTERN SLOPES
ON WEDS...FOLLOWED BY POST FRONTAL SW TO WEST WINDS WEDS NIGHT INTO
THURS ACRS THE ENTIRE CWA...WITH HIGHEST GUSTS IN THE DACKS/SLV.
PROGS SHOW THE DEVELOPMENT OF A LLVL SE JET OF 55 TO 65 KNOTS WEDS
MORNING ACRS OUR SOUTHERN ZNS...AND LIFTING NORTH THRU THE DAY.
LOCAL 4KM WRF AND 12KM NAM SOUNDINGS SHOW TOP OF THE MIXED LAYER
WINDS BTWN 40 AND 50 KNTS...WITH SOME HIGHER VALUES JUST ABOVE THE
MIXED LAYER. FEEL THIS WL SUPPORT AT LEAST WIND ADVISORY CRITERIA
ALONG THE WESTERN SLOPES FROM RUTLAND TO CAMBRIDGE...WITH POTENTIAL
FOR EXPOSED MTN TOP LOCATIONS TO GUSTS TO 60 MPH OR SO ON WEDS. THE
NEXT THREAT WL BE WINDS ASSOCIATED WITH SHARP PRES RISE COUPLET WEDS
NIGHT INTO THURS AS A 977MB LOW PRES LIFTS INTO SOUTHERN CANADA.
GIVEN...DEVELOPING DEEP MIXED LAYER AND FAVORABLE SW CHANNELING ACRS
THE SLV...FEEL SFC WINDS WL HAVE THE POTENTIAL TO BE BTWN 25 AND 35
MPH WITH GUSTS UP TO 50 MPH ON WEDS NIGHT INTO THURS.
MEANWHILE...WINDS WL BE BTWN 20 AND 30 MPH WITH GUSTS TO 45 MPH ACRS
THE REST OF THE FA ON LATE WEDS NIGHT INTO THURS.
PRECIP TYPE/QPF AMOUNTS: GIVEN...INITIAL SFC TRACK TO OUR
WEST...EXPECT THE 1000-500MB 540 LINE TO BE A GOOD INDICATOR OF THE
SNOW TO MIX TO RAIN LINE ACRS OUR CWA. IN ADDITION...EXPECT STRONG
SE GRADIENT TO WARM DOWNSLOPING REGIONS OF THE GREEN MTNS QUICKER
THAN MODELS HAVE FCST AND LIMIT OVERALL QPF FROM RUTLAND TO
UNDERHILL TO CAMBRIDGE ON WEDS. HOWEVER...THE WORCESTER RANGE AND ON
THE SE UPSLOPE REGIONS OF THE GREEN MTNS FROM LUDLOW TO JAY PEAK WL
SEE ENHANCED PRECIP AND LONGER DURATION OF FROZEN PRECIP...DUE TO
UPSLOPE COOLING EFFECTS. THE SAME WL OCCUR ON THE SE UPSLOPE REGIONS
OF THE DACKS. ALSO...SE DOWNSLOPE WINDS OFF THE WHITE MTNS WL LIMIT
QPF AMOUNTS ACRS THE UPPER CT RIVER VALLEY ON WEDS. VERTICAL
SOUNDINGS ACRS THE FA...SHOW A COMPLEX THERMAL PROFILE WITH WARMING
BTWN 850-700MB OF ABOVE 0C BY 18Z WEDS...BUT A SIGNIFICANT COLD
LAYER BTWN 950MB AND 850MB OF TEMPS BTWN -2 AND -4C....BEFORE BL
TEMPS WARM TO ABOVE 0C AGAIN. GIVEN DEPTH OF FREEZING LAYER...EXPECT
A BAND OF FREEZING RAIN/SLEET TO BE POSSIBLE IN THE HIGHER
ELEVATIONS BTWN 1500 FT AND 2500 FT...ESPECIALLY ACRS
CENTRAL/SOUTHERN VT AND THE DACKS ON WEDS. MEANWHILE...ACRS THE
HIGHER TRRN OF THE NORTHERN GREEN MTNS/NEK...SOUNDINGS SHOW WARM
LAYER OF +1 TO +3C DEVELOPING AFT 21Z WEDS...THEREFORE SNOW WL
CHANGE TO A WINTRY MIXTURE WITH RAIN AND POCKETS OF FREEZING RAIN
IN THE DEEPER VALLEYS. LIMITED DEEP/COLD SNOW PACK AND STRONG
WINDS WL HELP TO MIX LLVL COLD DENSE AIRMASS OUT OF THE DEEPER
VALLEYS QUICKER ON WEDS. THINKING SNOWFALL TOTALS WL BE A TRACE TO
2" CPV/WESTERN SLOPES (RUT TO CAMBRIDGE)...WITH 1 TO 3 INCHES FOR
CENTRAL/SOUTHERN MTNS...AND 2 TO 5" DACKS AND NORTHERN GREEN MTNS
IN VERMONT BY 00Z THURS. FEEL SOME ICE ACCUMULATION WL BE POSSIBLE
BTWN 1500 TO 2500 FEET ACRS THE DACKS/GREEN MTNS ON WEDS
AFTN/EVENING. IN ADDITION...COOL NE DRAINAGE WINDS DOWN THE
SLV...COULD RESULT IN SOME ICE ACCUMULATION NEAR MSS ON WEDS
AFTN/EVENING.
OVERALL QPF FROM INITIAL WAA LIFT/MOISTURE WL BE AROUND 0.25" ACRS
THE CPV/WESTERN SLOPES TO 0.25 TO 0.50" EASTERN/CENTRAL VT AND PARTS
OF THE DACKS/SLV. TEMPS WL BE TRICKY AND HIGHLY DEPEND UPON
ELEVATION AND WINDS...EXPECT WARMEST TEMPS IN THE DOWNSLOPE AREAS.
IF SECONDARY DEVELOPMENT ALONG THE COAST OCCURS QUICKER THAN
FCST...WARMER AIR ALOFT WL HAVE DIFFICULTIES REACHING OUR
FA...RESULTING IN GREATER SNOWFALL AMOUNTS. ITS A COMPLEX SFC SETUP
WITH A DIFFICULT THERMAL PROFILE TO PINPOINT ATTM. STAY TUNED AND
EXPECT CHANGES IN THE UPCOMING FCSTS.
WEDS NIGHT...MID/UPPER LVL DRY SLOT WL ADVECT FROM SOUTH TO NORTH
ACRS OUR CWA...WITH BEST DEEP LAYER MOISTURE STAYING ACRS THE
DACKS/SLV AND EXTREME NORTHERN VT ZNS. EXPECT MOST OF THE STEADIER
PRECIP TO TAPER OFF TO AREAS OF DRIZZLE/FREEZING DRIZZLE...BUT AS
HGHTS FALL AND LLVL CAA DEVELOPS TOWARD THURS MORNING...PRECIP WL
CHANGE BACK TO SCATTERED SNOW SHOWERS. SOME LIGHT ACCUMULATION WL
BE POSSIBLE ACRS THE HIGHER TRRN. TEMPS WL REMAIN NEARLY STATIONARY
OVERNIGHT IN THE 30S MOST AREAS.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 300 PM EST MONDAY...HIGHLIGHTS DURING EXTENDED PORTIONS OF
THE FCST FROM THURSDAY ONWARD WILL BE CHILLY TEMPERATURES ALONG
WITH SCT TO NUMEROUS SHSN ACROSS THE MTNS AND LK SNOWBELTS. LATEST
MEDIUM RANGE OPERATIONAL AND SUPPORTING ENSEMBLE MEMBERS SHOWING
AFOREMENTIONED DEEP LOW PRESSURE PULLING AWAY INTO ERN
CANADA/MARITIMES THROUGH THE COURSE OF THU/THU NIGHT AS SFC COLD
FRONT SWEEPS WELL EAST. WILL ADVERTISE MAINLY MORNING HIGHS ON
THURSDAY AS TEMPS FALL THROUGH THE DAY UNDER STRONG CAA AND 850 MB
TEMPS FALL INTO THE -10 TO -12C RANGE BY EARLY EVENING. FCST
SOUNDING PROGS CONTINUE TO SHOW IMPRESSIVE TURBULENT MIXING
THROUGH THE DAY AS BNDRY LYR DEPTH INCREASES TO NEAR 800
MB...EASILY TAPPING INTO STRONGER WESTERLY FLOW ALOFT. WILL
ADVERTISE GUSTS FROM 35 TO 45 MPH IN THE GRIDDED DATA AND AS EVENT
DRAWS CLOSER COULD EASILY SEE HIGHER VALUES HERE...ESP IN THE ST
LAWRENCE/FAR NRN CHAMPLAIN VALLEY WHERE ENHANCED CHANNELING LIKELY
TO DEVELOP.
THEREAFTER...MEAN WESTERLY FLOW SLOWLY ABATES FROM THURSDAY NIGHT
ONWARD AS ANY PCPN BECOMES MORE CONFINED TO OROGRAPHICALLY FAVORED
LOCALES AND THE LK ONTARIO SNOWBELTS. WILL MENTION SOLID CHC POPS
(30-50%) IN THE GREENS...AND CHC/LIKELY (40-60%) ACROSS THE DACKS AND
SNOWBELTS OF SRN ST LAWRENCE/SRN FRANKLIN COUNTIES FROM THU NIGHT
INTO EARLY SAT. DEEPER VALLEY SHOULD REMAIN ESSENTIALLY DRY WITH A
FEW PASSING LIGHT SHSN/FLURRIES FROM TIME TO TIME. MEAN 925-850 MB
TEMPS QUITE CHILLY WHICH SHOULD ENSURE A RATHER COLD STETCH ON TAP
WITH HIGHS GENERALLY IN THE 18-28 RANGE AND LOWS 5 TO 15 ABOVE OR
SO. GIVEN SUCH MILD RECENT WEATHER THIS WILL BE A REALITY CHECK THAT
YES...AFTER ALL IT IS DECEMBER IN THE NORTH COUNTRY. WEAK HIGH
PRESSURE THEN BUILDS ACROSS THE REGION BY SAT AFTERNOON WITH
COLD/DRY CONDS EXPECTED. BY SUNDAY/SUNDAY EVENING...REINFORCING SHOT
OF COLDER AIR PUSHES ACROSS THE AREA WITH A RENEWED THREAT OF
SHSN...ESP ACROSS THE NORTHERN MTNS. A GENERAL RETURN TO COLD/DRY
WEATHER IS EXPECTED BY EARLY NEXT WEEK W/ADDL HIGH PRESSURE.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
THROUGH 00Z WEDNESDAY...A WEAK AREA OF LOW PRESSURE WILL MOVE OFF
THE NEW ENGLAND COAST OVERNIGHT WITH LIGHT SNOW TAPERING OFF TO
SCATTERED FLURRIES AFTER 06Z TUESDAY. CONDITIONS WILL VARY FROM
VFR TO MVFR OVERNIGHT. A RIDGE OF HIGH PRESSURE WILL BUILD INTO
THE REGION AFTER 12Z ON TUESDAY...WITH VFR CONDITIONS EXPECTED
ACROSS THE REGION BY 18Z ON TUESDAY.
00Z WEDNESDAY THROUGH SATURDAY...VFR WITH HIGH PRES TUE NIGHT
THRU 06Z. RAPID DEVELOPMENT OF MODERATE SNOW FROM SW-NE 06-12Z WED
FOLLOWED BY A MIX AND CHANGEOVER TO SLEET AND THEN RAIN DURING THE
DAY WEDNESDAY. MIXED PCPN WILL BE HEAVY AT TIMES WITH IFR
CONDITIONS THRU 04Z THU. GUSTY SELY WIND CONDITIONS ARE ALSO
EXPECTED MUCH OF WED AND WED NIGHT...ESPECIALLY AT KRUT. 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. VFR ON SATURDAY...AS A RIDGE OF
HIGH PRESSURE BUILDS INTO THE REGION.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...TABER
NEAR TERM...TABER/LAHIFF
SHORT TERM...TABER
LONG TERM...JMG
AVIATION...EVENSON/WGH
