FXUS61 KBTV 050527
AFDBTV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
1227 AM EST SAT DEC 5 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 THIS MORNING/...
AS OF 924 PM EST FRIDAY...ONCE AGAIN THE EVENING FORECAST REMAINS
ON TRACK...JUST SOME MINOR TWEAKS TO SLIGHTLY LOWER TEMPERATURES
IN SOME LOCATIONS WHERE DECREASED CLOUD COVER IS LEADING TO BETTER
RADIATIONAL COOLING. THIS IS GENERALLY IN EASTERN VT AND THE
CHAMPLAIN VALLEY. SATELLITE AND RADAR BOTH SHOW A STREAM OF LIGHT
LAKE EFFECT SHOWERS IN THE ST. LAWRENCE VALLEY WITH MORE SPOTTY
SHOWERS IN THE ADIRONDACKS AND EVEN A WIDELY SCATTERED FLURRY OR
TWO IN NORTHERN VERMONT. THESE SHOWERS WILL TAPER DOWN AFTER
MIDNIGHT. SATELLITE ALSO SHOWS THE LEADING EDGE OF HIGH CLOUDS
MOVING INTO EXTREME SOUTHERN VT FROM THE NORTHEAST'S NEXT
ADVANCING STORM SYSTEM. MORE ON THAT BELOW IN THE SHORT TERM SECTION...
FROM PREVIOUS DISCUSSION...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 THIS 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 FRIDAY/...
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 /05Z SATURDAY THROUGH WEDNESDAY/...
THROUGH 12Z SUNDAY...A STORM SYSTEM ORGANIZING OFF THE CAROLINA
COAST WILL CONTINUE TO SPREAD MID-UPR LEVEL CLOUDS NORTHWARD
ACROSS THE REGION EARLY THIS MORNING...BUT CEILINGS ARE EXPECTED
TO REMAIN IN THE VFR CATEGORY. SWLY LOW-LEVEL FLOW FROM LAKE ONTARIO
IS ALLOWING FOR A SEPARATE BAND OF CLOUDS WITH CIGS 5-7 KFT NEWD
ACROSS THE ST. LAWRENCE VALLEY. THIS WILL REMAIN IN PLACE THROUGH
12Z AND THEN GRADUALLY DISSIPATE MID-LATE MORNING.
SFC LOW PRESSURE WILL PASS WELL SOUTHEAST OF NEW ENGLAND LATE THIS
AFTN AND EVENING. IT APPEARS THE NWRN EDGE OF ANY LIGHT SNOW
ACTIVITY WILL REACH RUT/MPV...WITH A PERIOD OF MVFR CONDITIONS
POSSIBLE BETWEEN 21-03Z. OTHERWISE...ANTICIPATE OVERCAST
CONDITIONS BUT NO PCPN EXPECTED. WINDS WILL GENERALLY BE LIGHT
FROM THE NORTH TO NORTHWEST DURING THE DAYLIGHT HRS SATURDAY...AND
THEN REMAIN SO THRU 12Z SUN.
OUTLOOK 12Z SUNDAY THROUGH WEDNESDAY...A WEAK CLIPPER SYSTEM WILL
BRING A CHANCE FOR LIGHT SNOW AND GENERALLY MVFR CONDITIONS TO
THE NORTH COUNTRY MONDAY AFTN/EVE. A MORE SIGNIFICANT STORM SYSTEM
IS POSSIBLE WITH MIXED PCPN DEVELOPING DURING THE DAY WEDNESDAY
WITH LOCALLY STRONG WINDS AND MVFR/IFR CONDITIONS. OTHERWISE...MAINLY
VFR CONDITIONS ARE EXPECTED FOR SUN/SUN NIGHT...AND FOR TUE/TUE
NIGHT.
&&
.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...AMF/TABER
SHORT TERM...TABER
LONG TERM...EVENSON
AVIATION...BANACOS
CLIMATE...TEAM BTV
