FXUS61 KBTV 302045
AFDBTV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
345 PM EST MON NOV 30 2009
.SYNOPSIS...
A RIDGE OF SURFACE HIGH PRESSURE WILL GRADUALLY BUILD INTO THE NORTH
COUNTRY OVERNIGHT...RESULTING IN DIMINISHING NORTH WINDS AND
PARTIAL CLEARING TOWARD DAYBREAK. ANY LINGERING SNOW SHOWER OR
FLURRY ACTIVITY WILL BE LIGHT AND MAINLY CONFINED TO THE MOUNTAINS
TONIGHT. A WEAKENING UPPER LEVEL DISTURBANCE WILL MOVE SOUTHEASTWARD
ACROSS THE REGION TUESDAY RESULTING IN LIGHT SNOW SHOWERS...MAINLY
ACROSS THE NORTHERN ADIRONDACKS. AFTER A PLEASANT AND SEASONABLE DAY
WEDNESDAY...A STRONG LOW PRESSURE SYSTEM MOVES NORTHWARD FROM THE
TENNESSEE AND OHIO VALLEY REGION BRINGING RAINY AND WINDY
CONDITIONS TO THE NORTH COUNTRY WEDNESDAY NIGHT INTO THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
AS OF 337 PM EST MONDAY...CLOUDY SKIES PREVAIL ACROSS THE NORTH COUNTRY
THIS AFTN IN THE WAKE OF THE SFC COLD FRONT WHICH SWEPT SEWD THRU
THE FORECAST AREA DURING THE MORNING HRS. PARTIAL CLEARING IS
NOTED NORTH OF LAKE ONTARIO...ASSOCIATED WITH LOW-LEVEL DRYING AND
INCREASED SUBSIDENCE WITH RIDGE AXIS IN PLACE ACROSS SERN ONTARIO.
LOW-LEVEL CAA WILL CONTINUE FOR SEVERAL MORE HRS WITH NWLY/NLY
WIND REGIME. SFC WINDS OF 5-10 MPH WILL GRADUALLY SUBSIDE THIS
EVENING AS SFC RIDGE BUILDS EWD...CRESTING OVER THE CHAMPLAIN
VALLEY AROUND 06Z. A FEW BREAKS IN THE OVERCAST CAN BE EXPECTED
LATE TONIGHT PER UPSTREAM OBS AND MODEL RH FIELDS...AND LIGHT
WINDS MAY ALLOW FOR INCREASED RADIATIONAL COOLING EFFECTS JUST
BEFORE DAYBREAK. LOW TEMPERATURES SHOULD RANGE FROM MID 20S ACROSS
MOST VALLEY LOCATIONS...AND IN THE UPR TEENS FOR THE NRN
ADIRONDACKS AND FAR NERN VT GIVEN EXPECTATION FOR PARTIAL
CLEARING. OTHERWISE...HAVE INCLUDED JUST A 20 PERCENT CHANCE OF A
FEW LIGHT SNOW SHOWERS OR FLURRIES...MAINLY THRU MIDNIGHT
ASSOCIATED WITH SHALLOW INSTABILITY AND MOISTURE. ANY LIGHT SNOW
SHOWER ACTIVITY WILL MAINLY BE CONFINED TO NWLY UPSLOPE FLOW AREAS
OF THE NRN ADIRONDACKS AND GREEN MTNS.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
AS OF 337 PM EST MONDAY...MAIN FORECAST ISSUE ON TUESDAY IS POTENTIAL LAKE
ENHANCED SNOWS FROM LAKE ONTARIO...AND NORTHWARD AND EWD EXTENT
OF THESE SNOW SHOWERS ACROSS ST. LAWRENCE AND FRANKLIN COUNTIES IN
NY. A WEAKENING SFC-700MB TROUGH TRACKS ESEWD FROM SERN ONTARIO AT
12Z TUESDAY INTO VT BY AFTN. THIS SYSTEM WILL BRING INCREASED MID-
LEVEL CLOUD COVER...BUT ALSO HELP TO STEEPEN LAPSE RATES VCNTY
LAKE ONTARIO WITH MEAN SFC-850MB WIND VECTORS BACKING TO 230DEG
AHEAD OF THE APPROACHING TROUGH. MOST GUIDANCE BRINGS LAKE ONTARIO
ENHANCED SNOW BAND AND MOISTURE ENEWD INTO SRN ST. LAWRENCE COUNTY
AND FRANKLIN COUNTY FOR SEVERAL HRS DURING THE DAY TUESDAY. WE
HAVE INCORPORATED THIS INTO THE FCST...WITH LOCALIZED D-2" SNOW
AMTS POSSIBLE...MAINLY IN SERN ST. LAWRENCE/SRN FRANKLIN COUNTIES
BEFORE BAND SHIFTS SWD AND WEAKENS. MOST OF THE ACCUMULATION WILL
BE ABOVE 1 KFT WITH VALLEY TEMPS GETTING ABOVE FREEZING TUESDAY
AFTN. ELSEWHERE...DECAYING NATURE OF UPR TROUGH SUGGESTS NOT MUCH
IN THE WAY OF PCPN OUTSIDE OF LAKE ENHANCED ZONE. INCLUDED 20-30
POPS FOR THE HIGHER ELEVATIONS OF VT DURING TUESDAY AFTN...BUT
LITTLE IF ANY SNOW ACCUMULATION IS EXPECTED. A BRIEF SPRINKLE OR
FLURRY IS POSSIBLE IN THE CHAMPLAIN AND CT RIVER VALLEYS TUES
AFTN. STAYED NEAR MAV/MET BLEND FOR HIGH TEMPERATURES...MAINLY MID
30S 1-2 KFT AND UPR 30S TO NEAR 40F IN THE IMMEDIATE CHAMPLAIN/ST.
LAWRENCE/CT RIVER VALLEY AREAS.
UPR TROUGH MOVES PAST TUESDAY NIGHT WITH HIGH PRESSURE IN CONTROL
MUCH OF TUESDAY NIGHT AND WEDNESDAY. VARIABLY CLOUDY SKIES AND
INCREASING 1000-500MB HEIGHTS/850MB TEMPS SHOULD KEEP LOWS
SEASONABLE TUESDAY NIGHT - MAINLY IN THE 20S. ON WEDNESDAY...PARTLY
SUNNY CONDITIONS ARE EXPECTED THRU EARLY AFTN WITH BROAD SLY TO SWLY
LOW-LEVEL FLOW RESULTING IN 850MB TEMPS WARMING TO NEAR +4C DURING
THE AFTN. TEMPERATURES SHOULD RECOVER NICELY WITH HIGHS IN THE LOW
TO MID 40S...EXCEPT AROUND 40 FOR THE NORTHEAST KINGDOM OF VT.
CLOUDS STEADILY INCREASE MID-LATE AFTN WEDNESDAY WITH APPROACH OF
STRONGER ISENTROPIC ASCENT ASSOCIATED WITH TN/OH RIVER VALLEY LOW
PRESSURE CENTER. USED 15Z SREF CONSENSUS TO INDICATE A CHANCE OF
RAIN SHOWERS REACHING OUR SWRN FORECAST AREA DURING THE 21-00Z
PERIOD.
12Z NWP SUITE CONTINUES TO FAVOR AN INLAND STORM TRACK WITH RATHER
INTENSE LOW PRESSURE TRACKING NWD ACROSS ERN OH AND WRN NY
STATE...WITH THE NORTH COUNTRY IN STRONG SOUTHERLY DEEP LAYER FLOW
AND WARM ADVECTION WEDNESDAY NIGHT. THE GFS SHOWS CENTRAL PRESSURE
OF THE LOW DOWN TO 983MB AS LOW PASSES NEAR KROC AT 12Z THURSDAY.
850MB TEMPS WARM TO NEAR +10C ACROSS THE NORTH COUNTRY. LOWS
WEDNESDAY NIGHT SHOULD GENERALLY REMAIN IN THE 40S...AND MAY WARM
OVERNIGHT WITH STRONG SLY FLOW. HAVE SHOWN POPS 80-90 PERCENT RANGE
BASED ON GOOD MODEL CONSISTENCY AND POTENTIAL FOR AT LEAST MODERATE
INTENSITY PCPN AS BEST WAA ASSOCIATED LIFT PASSES THRU THE REGION.
RAINFALL AMTS OF A HALF INCH TO AN INCH ARE POSSIBLE THRU 12Z
THURSDAY...AS DRY SLOT BEGINS TO WORK INTO THE REGION FROM THE SW.
DO NOT FORESEE ANY WINTER WEATHER CONCERNS BASED ON CURRENT TRACK.
WE WILL CONTINUE TO WATCH FOR THREAT OF STRONG WINDS...BUT STRONG
LOW-LEVEL STABILITY WILL PROBABLY CONFINE ANY GUSTS 35+ MPH TO ALONG
THE WRN SLOPES OF THE GREEN MTNS...AND ACROSS THE HIGHER ELEVATIONS
OF THE NRN ADIRONDACKS AND THE GREENS. HAVE SHOWN GUSTS 35-40 MPH IN
THESE LOCALIZED AREAS IN THE CURRENT SET OF FORECAST GRIDS.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 337 PM EST MONDAY...LARGE-SCALE SYSTEM WILL THEN BE IN THE PROCESS
OF CROSSING THE REGION DURING THURSDAY WITH WIDESPREAD PCPN. LATEST
MEDIUM RANGE ENSEMBLE SOLNS SUPPORT THIS MORNINGS OPERATIONAL RUNS
SHOWING PRIMARY SFC CENTER PASSING OVER OR JUST TO OUR WEST. THIS
WOULD ALLOW MILDER AIR TO CONTINUE STREAMING NORTHWARD...SUPPORTING
PRIOR REASONING FOR MAINLY AN ALL RAIN SCENARIO. SOME GUSTY WIND
POSSBL HERE AS WELL...THOUGH WITH STABILIZING INFLUENCE OF FALLING
PCPN AND CORE OF STRONGEST WINDS LIKELY ABOVE INVERSION HEIGHT
WILL DOWNPLAY THIS FOR NOW AND HIGHLIGHT ENHANCED VALUES IN
ELEVATED TERRAIN ONLY. PCPN SHOULD BEGIN TO TAPER TO SCT RAIN/SNOW
SHOWERS BY LATER IN THE DAY AND ESP BY THU NIGHT AS SYSTEM PULLS
AWAY ALONG WITH DEEPER MOISTURE.
BY FRI/FRI NT...PCPN TAKES ON A MORE OROGRAPHIC/LAKE ENHANCED
CHARACTER AS MEAN FLOW VEERS TO SOUTHWEST ALONG WITH GRADUALLY
COOLING TEMPS AS MEAN HEIGHTS/THICKNESS VALUES SLOWLY FALL
W/APPROACH OF DAMPENING POLAR TROUGH. HAVE LEANED CLOSE TO MEXMOS
TEMPS HERE...THOUGH WITH SOME SLIGHT MODIFICATIONS DUE TO EXPECTED
HIGH DEGREE OF CLOUD COVER.
THEREAFTER...SEASONABLY COLD WEATHER ALONG WITH SCT MAINLY NRN MTN
AND/OR LK EFFECT SHSN POSSBL BY SAT INTO MONDAY. BROADER VALLEYS TO
STAY ESSENTIALLY DRY DURING THESE PERIODS.
&&
.AVIATION /21Z MONDAY THROUGH SATURDAY/...
THROUGH 18Z TUESDAY...CONDS SLOWLY IMPROVING THROUGH TIME AS WE
PROGRESS INTO THE EVENING/OVERNIGHT HOURS. FRONTAL SYSTEM AND ANY
ASSOC LIGHT -SHRASN SHOULD END BY EARLY EVENING AS WELL. CIGS TO
TREND FROM IFR/MVFR TO VFR MOST AREAS AFTER 03Z OR SO AS MOISTURE
THINS AND NORTH/NORTHWEST FLOW GRADUALLY ABATES. THEN SCT/BKN VFR
CIGS AFT 12Z AS FLOW BACKS TO SOUTH/SOUTHWESTERLY. WEAKENING
SHORTWAVE FEATURE MAY SPARK A FEW LIGHT SHSN AND/OR SPRINKLES AT
THE NRN NY TERMINALS DURING THESE LATTER PERIODS...BUT ANY ACTIVITY
SHOULD REMAIN LIGHT.
OUTLOOK 18Z TUESDAY THROUGH SATURDAY...
18Z TUE THRU 00Z WED...SCATTERED MVFR SNOW SHOWERS POSSIBLE...MAINLY
DACKS.
00Z WED THRU 00Z THU...VFR.
00Z THU THRU 00Z FRI...MVFR/IFR IN RAIN AND GUSTY WINDS/LLWS POSSBL.
00Z FRI THRU 00Z SAT...VFR/MVFR IN SCATTERED SNOW SHOWERS..MAINLY
NRN MTNS.
00Z SAT THRU 00Z SUN...VFR/MVFR POSSBL IN LIGHT RAIN AND/OR SNOW.
&&
.CLIMATE...
BTV REMAINS WITHOUT MEASURABLE SNOWFALL SO FAR THIS SEASON. THE
RECORD LATEST DATE IS WITHIN SIGHT.
FOR BURLINGTON...ON AVERAGE THE FIRST MEASURABLE SNOW HAPPENS
NOVEMBER 6TH. HERE ARE THE 10 LATEST FIRST SNOWS FOR BURLINGTON
GOING BACK TO 1906...ALONG WITH THE SEASONAL TOTAL SNOW THAT
FOLLOWED.
SEASON TOTAL
RANK DATE SNOWFALL (INCHES)
1. 12/7/1937 45.1
2. 12/5/1915 54.4
3. 12/1/1948 40.7
4. 11/30/1918 69.6
11/30/1953 83.6
11/30/1960 51.6
7. 11/28/1913 56.5
8. 11/27/1941 57.7
9. 11/26/1982 80.5
10. 11/25/1957 94.9
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...BANACOS
NEAR TERM...BANACOS
SHORT TERM...BANACOS
LONG TERM...JMG
AVIATION...WGH/JMG
CLIMATE...TEAM_BTV
