FXUS61 KBTV 041951
AFDBTV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
251 PM EST FRI DEC 4 2009
.SYNOPSIS...
WEAK HIGH PRESSURE WILL PROVIDE THE NORTH COUNTRY WITH PARTLY CLOUDY
SKIES TONIGHT...WITH SOME LIGHT MOUNTAIN SNOW SHOWERS POSSIBLE.
OTHERWISE...DEVELOPING SURFACE LOW PRESSURE ACROSS THE NORTH GULF
COAST WILL TRACK TOWARD CAPE HATTERAS BY SATURDAY MORNING...THEN
WELL SOUTH OF THE NEW ENGLAND COAST LINE BY SATURDAY NIGHT. THIS
WILL INCREASE OUR CLOUDS WITH SOME LIGHT SNOW DEVELOPING ACROSS
CENTRAL...SOUTHERN...AND EASTERN VERMONT BY SATURDAY AFTERNOON. SOME
LIGHT SNOW ACCUMULATION WILL BE POSSIBLE...WITH TEMPERATURES MAINLY
IN THE 30S.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 250 PM EST FRIDAY...FCST FOCUS TONIGHT WL BE SNOW SHOWERS ASSOCIATED
WITH LAKE EFFECT ACRS NORTHERN NEW YORK INTO THE NORTHERN GREEN
MTNS. RADAR SHOWS WEAK BAND OF LAKE EFFECT PRECIP ACRS SOUTHERN
SAINT LAWRENCE COUNTY INTO THE NORTHERN DACKS THIS AFTN. USING THE
4KM WRF AND 12KM NAM...FEEL LAKE EFFECT BAND WL STRENGTH FOR A
SHORT TIME THIS EVENING...AS FETCH BCMS BETTER AND LLVL SHEAR
DECREASES. HOWEVER...BY 03Z SOUNDINGS SHOW SUBSIDENCE/DRY AIR
DEVELOPING WHICH WL LIMIT VERTICAL CLOUD GROWTH AND DEVELOPMENT OF
SNOW SHOWERS. IN ADDITION...CLOUD LAYER SHEAR INCREASES TWD 06Z AS
FLW BECMG WESTERLY AT THE SFC AND SW ALOFT. THE LOCAL 4KM DOES
SHOW QPF AMOUNTS APPROACHING 0.10" ACRS THE DACKS...THEREFORE WL
MENTION CHC POPS THRU 06Z TONIGHT. OTHERWISE...CLOUD LAYER WINDS
ARE NOT STRONG ENOUGH TO ADVECT SIGNIFICANT SNOW TO NORTHERN
VT...THEREFORE WL JUST MENTION CHC POPS ATTM. TEMPS WL DROP IN THE
M20S MTNS TO L/M 30S VALLEYS.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
AS OF 250 PM EST FRIDAY...THE MAIN CHALLENGE FOR SATURDAY INTO SATURDAY
NIGHT WL BE NORTHERN EXTENT OF ACCUMULATING SNOWFALL AND
POTENTIAL IMPACTS TO OUR FA. CRNT WATER VAPOR SHOWS DEEP MID/UPPER
LVL TROF DIGGING ACRS THE CENTRAL PLAINS WITH POTENT S/W ENERGY
ROUNDING THE TROF BASE ACRS THE NORTHERN GULF. THIS IS HELPING TO
PRODUCE -SN IN HOUSTON TX TODAY...AND WL ENHANCE SFC LOW PRES OVER
THE NORTHERN GULF BY THIS EVENING. HGHT AND UPPER AIR ANALYSIS
SHOW A POSITIVELY TILTED MID/UPPER LVL TROF ACRS OUR FA...WITH
LIMITED PHASING WITH NORTHERN STREAM ENERGY ACRS THE NORTHERN
PLAINS. THIS COMBINED WITH FAST SW TO NE FLW ALOFT ACRS THE SE
CONUS AND NO DIGGING NORTH TO SOUTH BACKSIDE JET WL LIMIT AMOUNT
OF QPF ACRS OUR CWA. FURTHERMORE...NO ANTICYCLONIC JET ASSOCIATED
WITH THE POLAR JET IS PRESENT...WHICH COMBINED WITH THE SFC LOW
TRACK SOUTHEAST AND OF THE BENCHMARK WL LIMIT IMPACTS TO OUR FA.
HOWEVER...LATEST MODEL TRENDS HAVE BEEN SLIGHTLY FURTHER NORTH WITH
SFC LOW TRACK AND SLIGHTLY MORE AGGRESSIVE WITH QPF/LIFT ACRS OUR
CWA. BOTH NAM/GFS SHOW BEST 850MB TO 700MB FGEN FIELDS ACRS SNE INTO
THE EASTERN MIDDLE ATLANTIC STATES...BUT GFS DOES SHOW A SECONDARY
AREA OF ENHANCED BUT MUCH WEAKER 850MB TO 750MB FGEN FORCING ACRS
CENTRAL/SOUTHERN VT BTWN 18Z-00Z SATURDAY. IN ADDITION...VERTICAL
CROSS SECTIONS SHOW BEST FGEN FORCING AND UVVS ABOVE 700MB ACRS MOST
OF OUR FA...SUGGESTING THESE DYNAMICS WL GO INTO INCREASING MOISTURE
INTO THE ATMOSPHERE.
LATEST STORM TOTAL QPF AMOUNTS AT VSF SHOW 0.40 OFF THE NAM...0.35
FROM THE GFS...AND 0.32 FROM THE LATEST 12Z 4KM WRF...WHILE AMOUNTS
AT MPV RANGE FROM 0.25 OFF THE NAM TO 0.11 OFF THE GFS....WITH ONLY
TRACE AMOUNTS AT BTV. INTERESTING...VIEWING THE 09Z SREF 3HR
ACCUMULATED PRECIP PLUMES...WHICH SHOW ONLY TWO MEMBERS PLACING QPF
AMOUNTS OF AROUND 0.10 AT MPV...WHILE THE REST SHOW A TRACE.
THEREFORE...GIVEN EXPECTED TRACK OF SFC LOW PRES AND NO CLOSED
CIRCULATIONS AT 7H OR 5H AND BEST DEEP LAYER LIFT/MOISTURE ACRS
SOUTHERN NEW ENGLAND...WL CUT QPF AMOUNTS...BUT MENTION LIKELY/CAT
POPS FOR LIGHT SNOW ACRS EASTERN/CENTRAL AND SOUTHERN VT. TOTAL SNOW
ACCUMULATIONS OF A TRACE TO SEVERAL INCHES WL BE POSSIBLE ALONG AND
SOUTH OF 1V4 TO MPV TO RUT LINE BY SAT NIGHT...WITH JUST FLURRIES
OR A BRIEF PERIOD OF VERY LIGHT SNOW ACRS THE CENTRAL/NORTHERN
CPV/NORTHERN VT...AND NO IMPACTS EXPECTED ACRS NORTHERN NY/SLV.
PROGGED 85H TEMPS BTWN -8C AND -10C AND ASSOCIATED NORTHERLY FLW WL
RESULT IN SFC TEMPS MAINLY IN THE 30S ACRS OUR CWA ON SAT.
BY SATURDAY NIGHT...MID/UPPER LVL ENERGY AND ASSOCIATED SFC LOW PRES
WL RACE INTO THE NORTHERN ATLANTIC...WITH ANY LEFTOVER LIGHT SNOW
TAPERING TO FLURRIES. SOUNDINGS SUPPORT SOME CLRING AFT 06Z
SUNDAY...ESPECIALLY ACRS NORTHERN VT AND NORTHERN NY AREAS.
OVERNIGHT LOWS WL BE TRICKY AND HIGHLY DEPEND UPON AMOUNT OF
CLRING...ATTM WL PLAY IT SAFE AND KEEP AT OR SLIGHTLY ABOVE MACHINE
NUMBERS MAINLY 20S. ON SUNDAY...LOW TO MID LVL FLW BECMS WEST TO
SOUTHWEST AND SOME LAKE EFFECT MOISTURE/SNOW SHOWERS WL IMPACT OUR
NORTHERN DACKS. HOWEVER...IMPACTS WL BE LIMITED DUE TO INCREASE SFC
TO CLOUD LAYER SHEAR AND WARMING ALOFT. WL MENTION LOW CHC
POPS...WITH NO ACCUMULATION. 85H TEMPS NEAR -10C SUPPORT NEAR NORMAL
HIGHS IN THE 30S MOST LOCATIONS. SUNDAY NIGHT...LOW/MID LVL WAA
DEVELOPS AND 850 TO 500MB MOISTURE INCREASES FROM WEST TO EAST ACRS
OUR CWA BY 12Z MONDAY. BEST DYNAMICS ASSOCIATED WITH MID LVL VORT
AND WAA WL APPROACH OUR CWA AFT 12Z MONDAY...THEREFORE WL JUST
MENTION SCHC POPS ATTM. HOWEVER...GIVEN FAST FLW ALOFT...WOULD NOT
BE SURPRISED IF LIGHT ADVECTION PRECIP ARRIVES SOONER THAN
ADVERTISED. INITIALLY TEMPS WL BE COLD ENOUGH TO SUPPORT ALL SNOW.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 250 PM EST FRIDAY...TREND TOWARD A MORE ACTIVE PERIOD OF WEATHER
IS EXPECTED IN THE EXTENDED FORECAST. BEGINNING ON MONDAY...THE
COMBINATION OF INCREASING DYNAMIC SUPPORT ASSOCIATED WITH A
SHORTWAVE TROUGH AND STEEPENING LAPSE RATES TO ENHANCE INSTABILITY
SUGGESTS A GREATER POTENTIAL FOR SNOW SHOWERS MONDAY AFTERNOON
INTO THE FIRST PART OF MONDAY. WE COULD BE LOOKING AT SOME MINOR
SNOW ACCUMULATIONS WITH THIS EVENT. A BRIEF BREAK IN THE ACTION IS
EXPECTED FOR TUESDAY AS HIGH PRESSURE BUILDS INTO THE REGION. AT
THIS TIME...STRONGER THAN NORMAL UPPER TROUGH WILL BE TAKING SHAPE
OVER THE SOUTHWEST UNITED STATES...WHICH WILL EVENTUALLY MOVE
TOWARD THE NORTHEAST UNITED STATES. SOUTHWEST FLOW ALOFT BECOMES
ESTABLISHED OVER THE AREA ON WEDNESDAY AND WITH STRONG TROUGH
MOVING IN...DOUBLE SURFACE LOW STRUCTURE TO DEVELOP WITH PRIMARY
LOW GOING TO OUR WEST AND SECONDARY LOW MOVING INTO OUR AREA. WILL
HAVE TO MONITOR THIS SITUATION AS IT WILL BE A LARGE PRECIPITATION
PRODUCER AND THERMAL PROFILE STILL UNDETERMINED AT THIS TIME.
INITIAL THOUGHT IS LOWEST 1000 FEET OR SO MAY BE WARM ENOUGH TO
HAVE A MIX OF RAIN OR SNOW AND WILL GO WITH THIS IDEA FOR NOW.
HAVE RAISED PRECIPITATION CHANCES AS SEVERAL PIECES OF DATA
SUPPORT AN EVENT OCCURRING ON WEDNESDAY. COLDER AIR COMES IN LATER
WEDNESDAY NIGHT AND THURSDAY AS LOW LEVEL NORTHWEST FLOW ALOFT
DEVELOPS AND ENHANCES UPSLOPE PRECIPITATION ON THURSDAY.
EVENTUALLY HIGH PRESSURE BUILDS IN FOR FRIDAY FOR DRIER WEATHER.
&&
.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
THROUGH 18Z SATURDAY...MOISTURE FROM THE EASTERN GREAT LAKES WILL
CONTINUE TO MOVE ACROSS THE AREA THIS AFTERNOON THROUGH EARLY
EVENING. CEILINGS WILL GENERALLY BE IN THE VFR CATEGORY...BUT
LOWER TO MVFR AT TIMES. SOME LIGHT LAKE EFFECT PRECIPITATION WILL
MOVE INTO THE REGION THIS AFTERNOON THROUGH ABOUT 02Z AND MAINLY
BE FROM THE CHAMPLAIN VALLEY WESTWARD TO THE SAINT LAWRENCE
VALLEY. VISIBILITIES WILL REMAIN IN THE VFR CATEGORY...BUT WILL
LOWER AT TIMES INTO THE MVFR CATEGORY OVER THE NORTHERN
ADIRONDACKS. EXPECT VFR CONDITIONS ALL AREAS GENERALLY AFTER 04Z
THROUGH THE REMAINDER OF THE PERIOD. WINDS WILL BE FROM THE WEST
AND SOUTHWEST AT SPEEDS OF 10 KNOTS OR LESS THROUGH THIS EVENING
WITH LIGHT AND VARIABLE WINDS FOR THE REMAINDER OF THE PERIOD.
OUTLOOK 18Z SATURDAY THROUGH TUESDAY...
18Z SATURDAY THRU 18Z MONDAY...MAINLY VFR...AS A RIDGE OF HIGH PRESSURE
BUILDS INTO THE REGION.
18Z MONDAY THRU 12Z TUESDAY...IFR/MVFR IN LIGHT SNOW...AS A LOW PRESSURE
AREA APPROACHES THE REGION FROM THE GREAT LAKES.
12Z TUESDAY THRU 00Z WEDNESDAY...MAINLY VFR WITH SOME MVFR IN SCATTERED
SNOW SHOWERS.
&&
.CLIMATE...
MORE INTERESTING SNOWFALL DATA FOR BURLINGTON...COUNTING TODAY
DECEMBER 4TH OUR LAST MEASURABLE SNOWFALL OCCURRED ON APRIL
8TH...WHICH IS 240 DAYS AGO. THIS RANKS 3RD LONGEST STREAK WITHOUT
MEASURABLE SNOWFALL AT BTV...BEHIND 247 DAYS IN 1948 AND 248 DAYS IN
1945. THE TOP 2 SHOULD REMAIN IN TACT...WITH SOME LIGHT SNOW
ACCUMULATION POSSIBLE BY NEXT WEEK.
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/?/2009 ????
4. 12/1/1948 40.7
5. 11/30/1918 69.6
11/30/1953 83.6
11/30/1960 51.6
8. 11/28/1913 56.5
9. 11/27/1941 57.7
10. 11/26/1982 80.5
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...TABER
NEAR TERM...TABER
SHORT TERM...TABER
LONG TERM...EVENSON
AVIATION...EVENSON/NEILES
CLIMATE...
