FXUS61 KBTV 071504
AFDBTV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
1004 AM EST MON DEC 7 2009
.SYNOPSIS...
NOW SHOWERS WILL BECOME MORE WIDESPREAD TODAY AS A WEAK CLIPPER
SYSTEM MOVES EASTWARD ACROSS THE NORTH COUNTRY. THE SNOW WILL
GRADUALLY TAPER OFF OVERNIGHT TONIGHT. TOTAL ACCUMULATIONS WILL
GENERALLY RANGE FROM A DUSTING TO 3 INCHES WITH THE HIGHEST AMOUNTS
IN THE MOUNTAINS. OTHER THAN A FEW LIGHT SNOW SHOWERS IN THE
MOUNTAINS...TUESDAY WILL BE MAINLY DRY. PRECIPITATION RETURNS LATE
TUESDAY NIGHT AS A STRONG STORM SYSTEM APPROACHES FROM THE MIDWEST.
SNOW WEDNESDAY MORNING WILL BECOME A MESSY WINTRY MIX BY LATE
WEDNESDAY AFTERNOON.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 944 AM EST MONDAY...INTERESTING SYNOPTIC AND MESOSCALE
SYSTEM EXPECTED TO IMPACT FA THIS AFTN/EVENING. HAVE UPDATED FCST
TO INCREASE POPS ACRS NORTHERN NY AND MOST OF CENTRAL/NORTHERN VT
ZNS TODAY/TONIGHT. CRNT RADAR SHOWS A BAND OF LIGHT SNOW
DEVELOPING ACRS SOUTHERN SAINT LAWRENCE COUNTY INTO THE NORTHERN
DACKS ATTM. MEANWHILE...MORE SNOW SHOWERS ARE DEVELOPING ACRS THE
OHIO VALLEY/WESTERN PA ASSOCIATED WITH STRONG 250MB JET COUPLET OF
130 KNOTS. THIS ENHANCE ULVL DIVERGENCE IS EXPECTED TO LIFT ACRS
OUR CENTRAL/NORTHERN CWA BTWN 18Z-00Z TODAY...ALONG WITH A POTENT
5H VORT. THIS ENERGY ALOFT HAS ENHANCED SOME COOLER CLOUD TOPS
ACRS THE EASTERN GREAT LAKES AND WESTERN NY THIS MORNING. FEEL THE
COMBINATION OF GOOD ULVL DYNAMICS...DEEP SFC TO 500MB
MOISTURE...AND SOME LLVL LAKE MOISTURE/CONVERGENCE
INTERACTION...A BAND OF LIGHT TO MODERATE SNOW WL DEVELOP ACRS
NORTHERN DACKS INTO THE CENTRAL/NORTHERN GREEN MTNS TODAY.
GIVEN...LIGHT SOUTH TO SOUTHWEST FLW AND GOOD LLVL CONVERGENCE
ASSOCIATED WITH WINDS BCMG NORTHERLY AROUND SUNSET IN THE
CPV...WL RESULT IN ACCUMULATING SNOW...EVEN IN THE CPV. THE LATEST
NAM 12 SHOWS GOOD DEEP LAYER MOISTURE...A BAND OF STRONG 1000 TO
700MB OMEGA...AND PRODUCES QPF AMOUNTS NEAR 0.20" AT BTV BY 06Z
TONIGHT. THIS COMBINED WITH CRNT RADAR TRENDS...SUPPORT
ACCUMULATING SNOWFALL AT BTV BY THIS AFTN. WL MENTION 2 TO 4
INCHES ACRS SOUTHERN SAINT LAWRENCE COUNTY/NORTHERN DACKS...AND
NORTHERN GREEN MTNS IN VT. SOME LOW END ADVISORY AMOUNTS WL BE
POSSIBLE BY 12Z TUES NEAR JAY PEAK AND TUPPER LAKE/STAR LAKE
REGION OF 4 TO 5 INCHES. ELSEWHERE...EXPECTING 1 TO 3 INCHES ACRS
THE NORTHERN/CENTRAL CPV INCLUDING BTV/PBG AREAS AND CENTRAL VT...WITH
LESS AMOUNTS ACRS THE NORTHERN SLV AND SOUTHERN VT ZNS. GIVEN...BL
TEMPS WL WARM TO NEAR FREEZING TODAY BEFORE THE ARRIVAL OF THE
SNOW...EXPECT ROADS TO BECM VERY SLIPPERY TOWARD THE EVENING
COMMUTE AS THE SUNSETS AND SFC TEMPS DROP. IN
ADDITION...VISIBILITIES WL BE BLW 1SM AT TIMES ACRS THE CPV AND
OTHER PLACES ACRS THE NORTH COUNTRY...PRODUCING A HAZARDOUS
EVENING COMMUTE. WL CONT TO MONITOR FOR A POTENTIAL SPECIAL
WEATHER STATEMENT THIS AFTN...REGARDING THE EVENING COMMUTE.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 412 AM EST MONDAY...MAIN CONCERN FOR THE SHORT TERM PERIOD
IS THE STORM SYSTEM AND ASSOCIATED PRECIP TYPE FOR WEDNESDAY.
MORE ON THAT IN A BIT...
TUESDAY WILL BE FAIRLY QUIET AS SURFACE HIGH PRESSURE BUILDS INTO
THE NORTHEASTERN CONUS AND 500MB VORT PULLS AWAY FROM THE FORECAST
AREA. NORTH FLOW AROUND THE APPROACHING RIDGE WILL ALLOW FOR A FEW
LIGHT SNOW SHOWERS TO DEVELOP IN THE HIGHER ELEVATIONS. COMBINED
WITH 850MB TEMPS OF -8C TO -12C...THIS ALSO MEAN TEMPS WILL BE A FEW
DEGREES COOLER ON TUESDAY THAN WEDNESDAY. TUESDAY NIGHT THE HIGH
WILL MOVE DIRECTLY OVER THE FORECAST AREA BUT WILL BE QUICKLY
FOLLOWED BY INCREASING SOUTH FLOW AS A STRENGTHENING LOW PRESSURE
SYSTEM MOVES NORTHEAST THROUGH THE MIDWEST STATES. AS
SUCH...OVERNIGHT LOWS WILL BE EARLY THEN TEMPS WILL HOLD STEADY OR
RISE THROUGH THE REST OF THE NIGHT. USED GFS TEMPERATURES FOR THIS
PERIOD...WHICH GAVE MINS IN THE UPPER TEENS TO MID 20S. WARM
ADVECTION SNOW WILL BEGIN TO MOVE INTO SOUTHWESTERN PORTIONS OF THE
FORECAST AREA LATE TUESDAY NIGHT.
ALTHOUGH SLIGHT DIFFERENCES IN TIMING AND PLACEMENT
EXIST...FORECAST MODELS CONTINUE TO BE VERY CONSISTENT WITH
WEDNESDAY/S SYSTEM. BOTH THE 00Z ECMWF AND GFS PLACE A 980 LOW
OVER CHICAGO 12Z WEDNESDAY THEN MOVE IT OVER GEORGIAN BAY BY 00Z
THURSDAY WHILE DEEPENING IT TO AROUND 975MB. THE ECMWF FORMS A
SECONDARY LOW OFF THE MAINE COAST WITH A CENTRAL PRESSURE AROUND
984MB BY 00Z THURSDAY WHILE THE GFS KEEPS IT AN OPEN TROUGH. ECMWF
IS ALSO A BIT WARMER...PLACING THE 540DAM THICKNESS LINE IN THE
SAINT LAWRENCE VALLEY BY WEDNESDAY EVENING WHILE THE GFS HAS IT
LINED UP THROUGH THE CHAMPLAIN VALLEY. IN SPITE OF THESE
DIFFERENCES...OVERALL PICTURE SHOULD GENERALLY BE THE SAME. SNOW
WILL SPREAD ACROSS THE FORECAST AREA WEDNESDAY MORNING...A BURST OF
HEAVY SNOW IS POSSIBLE IN THE LATE MORNING/EARLY AFTERNOON AS STRONG
ISENTROPIC LIFT DEVELOPS OVER THE AREA. AS THE LOW PASSES TO THE
WEST WEDNESDAY AFTERNOON...STRONG SOUTHERLY FLOW OF 60+ KTS WILL
USHER IN WARM AIR...RAISING 850MB TEMPS SOME 5-8 DEGREES C. AS A
RESULT...SNOW WILL TRANSITION TO A MESSY MIX OF SNOW/SLEET/RAIN
DURING THE AFTERNOON. EXACT NORTHWARD EXTENT OF THE WARM AIR IS
DIFFICULT TO PINPOINT AT THIS TIME...BUT IT LOOKS LIKE THE SOUTHERN
3/4 OF THE FORECAST AREA WILL EVENTUALLY BE WARM ENOUGH FOR ALL RAIN
BY 00Z THURSDAY...WITH THE COLDEST AIR REMAINING TRAPPED IN THE
VALLEYS OF THE NORTHEAST KINGDOM. GIVEN THE UNCERTAINTIES INHERENT
WITH MIXED PRECIPITATION IN THIS TYPE OF SCENARIO...SNOWFALL TOTALS
ARE ALSO DIFFICULT TO FORECAST. MODEL CONSENSUS IS THAT SEVERAL
INCHES OF SNOW WILL BE POSSIBLE BEFORE THE CHANGE OVER TO RAIN WITH
THE NORTHERN MOUNTAINS SEEING THE HIGHEST ACCUMULATIONS. ALTHOUGH
TOUCHED UPON BRIEFLY ABOVE...ANOTHER CONCERN FOR WEDNESDAY WILL BE
WINDS. NAM AND GFS BOTH INDICATE A 65+ KT JET AROUND 3000 FT DURING
THE AFTERNOON. WITH ONGOING PRECIPITATION IT IS HARD TO SAY HOW MUCH
OF THIS WILL MIX DOWN TO THE SURFACE BUT GUSTS OVER 40 MPH ARE
POSSIBLE...ESPECIALLY IN THE HIGHER TERRAIN AND FAVORED GAP AREAS OF
THE SOUTHERN GREEN MOUNTAINS. STAY TUNED AS THIS STORM IS DEFINITELY
WORTH KEEPING AN EYE ON.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 350 AM EST MONDAY...A TREND TOWARD MORE WINTER LIKE
CONDITIONS IS EXPECTED ACROSS THE NORTH COUNTRY...WITH COLDER
TEMPERATURES AND BLUSTERY CONDITIONS ESPECIALLY ON THURSDAY AND
FRIDAY. THE COLD AIR MASS WILL HAVE AN EXTRA BITE TO IT GIVEN THE
EXPECTED WINDS AND THE ABRUPT CHANGE FROM THE PROLONGED MILD
WEATHER WE/VE HAD THROUGH MOST OF NOVEMBER AND DECEMBER TO THIS
POINT. SPECIFICS FOLLOW...
WEDNESDAY NIGHT: NO SIGNIFICANT CHANGE IN PREVIOUS GUIDANCE. WE
STILL ANTICIPATE DEEP SFC LOW /975MB/ VCNTY GEORGIAN BAY 00Z
THURSDAY WITH SOME COASTAL REFLECTION NEAR TRIPLE POINT VCNTY OF THE
GULF OF MAINE. THERMAL PROFILES AND CRITICAL THICKNESS VALUES IN 00Z
GFS AND ECMWF GENERALLY SUPPORT ENOUGH LOW-LEVEL WARMING FOR
GENERALLY RAIN 00-03Z THURSDAY AS LAST OF STEADY PCPN LIFTS NWD OUT
OF THE FORECAST AREA DURING THE EVENING HRS. STILL DON/T FORESEE
ENOUGH OF COASTAL REDEVELOPMENT TO HOLD ONTO THE LOW-LEVEL COLD AIR
ACROSS MOST OF OUR REGION. AS THE NIGHT CONTINUES...WINDS GRADUALLY
BECOME WEST-SOUTHWESTERLY AND LOW-LEVEL COOLING WILL OCCUR WITH THE
PROSPECT FOR SCATTERED RAIN/SNOW SHOWERS...TRENDING TO JUST SCT -SW
BY DAYBREAK THURSDAY. LOWS WILL GENERALLY BE AROUND 30F...EXCEPT MID
20S IN THE NRN ADIRONDACKS AS COLDER AIR FILTERS IN FROM THE WEST AS
SFC LOW DEPARTS NNEWD THRU WRN QUEBEC. I INDICATED THAT POPS
DECREASE FROM AROUND 80 PERCENT 00-06Z DOWN TO 30-40 PERCENT FROM
06-12Z WITH MORE OF A UPSLOPE/OROGRAPHIC CHARACTER TO THE SHOWERY
PCPN LATE IN THE PERIOD.
THURSDAY WILL FEATURE LOW-LEVEL CAA...AND STRONG WEST WINDS 15-25
KTS WITH GUSTS TO 35 KTS. P-GRADIENT REMAINS MODERATELY STRONG AS
DEEP CYCLONE PULLS AWAY NWD THRU QUEBEC. THE STRONG GUSTY WINDS WILL
BE WIDESPREAD GIVEN STEEP LOW-LEVEL LAPSE RATES IN SFC-800MB LAYER.
SOME LOCALLY STRONGER GUSTS ARE POSSIBLE ACROSS THE HIGHER
TERRAIN...ESPECIALLY IN THE ADIRONDACKS. TEMPERATURES WILL LIKELY
REMAIN STEADY THROUGHOUT THE DAY...IN THE MID 20S TO NEAR 30F AS CAA
AND STRATOCU DECK WINS OUT OVER ANY INSOLATIONAL HEATING. LOOK FOR
PERIODS OF SNOW SHOWERS...ESPECIALLY IN THE NRN ADIRONDACKS AND
CENTRAL/ERN VT. STRONG WLY FLOW OF 40-50 KTS AT 850MB SUGGESTS SOME
OF THE OROGRAPHIC SNOWFALL WILL BE DEPOSITED ALONG AND EAST OF THE
GREEN MTN SPINE...WITH 1-2" POSSIBLE IN FAVORED LOCATIONS OF
CENTRAL/N-CENTRAL VT. LIKEWISE...LAKE ONTARIO SNOWBAND SHOULD BECOME
ESTABLISHED IN WSW-ENE ORIENTATION BRINGING SOME MORE PERSISTENT
SNOW SHOWER ACTIVITY TO FAR SRN ST. LAWRENCE/FRANKLIN COUNTIES IN
NY. A BIT SOON TO SAY...BUT LOCALIZED 1-3" AMTS ARE POSSIBLE IN OUR
FAR SW FORECAST AREA.
THURSDAY NIGHT: LIKELY NOT A HUGE SPREAD IN TEMPERATURES ACROSS THE
NORTH COUNTRY AS WLY WINDS CONTINUE 10-20 KTS IN SOME LOCATIONS AND
MOISTURE FROM THE GREAT LAKES MAINTAIN BKN-OVC CONDITIONS. LOOKING
FOR MIN TEMPS GENERALLY IN THE LOW TO MID TEENS IN THE NRN
ADIRONDACKS AND THE NORTHEAST KINGDOM...AND AROUND 20F IN THE
IMMEDIATE CHAMPLAIN VALLEY. ANTICIPATE SCATTERED SNOW SHOWER
ACTIVITY TO PERSIST AS LOW-LEVEL CAA CONTINUES AND 1000-500MB
THICKNESS VALUES DROP TO 504-507DM BY 12Z FRI. LAPSE RATES REMAIN
STEEP SFC-800MB LAYER...AND THIS SHOULD LOCALLY ENHANCE SNOW SHOWERS
AND YIELD PERIODS OF GUSTY WINDS UP TO 30 KTS ESPECIALLY OVER THE
HIGHER TERRAIN.
FRIDAY: COLDEST DAY OF THE SEASON THUS FAR WITH 850MB TEMPS HOVERING
IN THE -15 TO -17C RANGE PER 00Z GFS ENSEMBLE GUIDANCE. BLUSTERY
CONDITIONS EXPECTED WITH WINDS 10-20 KTS AND HIGHS ONLY IN THE MID
20S IN THE VALLEYS AND MID-UPR TEENS IN THE 1-2 KFT ELEVATIONAL
LAYER. OROGRAPHIC SNOW SHOWERS PERSIST IN NWLY FLOW...THOUGH LOWER
DEWPOINTS SHOULD KEEP ACTIVITY A BIT MORE CONFINED TO THE MTNS. SNOW
RATIOS WILL BE LARGE WITH LOCALIZED ACCUMULATIONS CENTRAL/NRN
GREENS AND IN THE NRN ADIRONDACKS.
FRIDAY NIGHT THRU SUNDAY: SFC RIDGE BUILDS INTO THE REGION FRIDAY
NIGHT ALLOWING WINDS TO SUBSIDE. WITH OPEN GREAT LAKE
WATERS...DIFFICULT TO FORESEE CLEAR SKIES WITH WLY DEEP-LAYER FLOW
ALOFT STILL IN PLACE...BUT A BIT BETTER SITUATIONAL FOR RADIATIONAL
COOLING SHOULD YIELD LOWS IN THE UPR SINGLE DIGITS FOR THE NRN
DACKS/NERN VT AND LOW TEENS IN THE BROADER VALLEYS. GRADUAL
MODERATION IN SFC TEMPERATURES EXPECTED OVER THE WEEKEND AS SFC
RIDGE SHIFTS EWD AND LOW-LEVEL FLOW BECOMES SWLY. ECMWF IS A BIT
MORE BULLISH ON THE WARMING WITH 850MB TEMPS UP TO -7C BY 00Z
SUNDAY. FOR NOW...KEPT THINGS SLIGHTLY BELOW SEASONAL NORMS WITH
VALLEY HIGHS IN THE MID TO UPR 20S. NO SIGNIFICANT PCPN FORESEEN
DURING THE FRI NIGHT-SUNDAY PERIOD AT THIS TIME.
&&
.AVIATION /15Z MONDAY THROUGH FRIDAY/...
THRU 12Z TUESDAY...MOISTURE FROM THE ERN GREAT LAKES WILL CONTINUE
TO YIELD BROKEN TO OVERCAST SKIES ACROSS THE NORTH COUNTRY
THROUGHOUT THE TAF PERIOD. THRU 16Z...CEILINGS WILL GENERALLY
REMAIN IN THE VFR CATEGORY...EXCEPT LOCALLY/BRIEFLY MVFR IN LIGHT
SNOW SHOWER ACTIVITY - MAINLY AT KSLK DUE TO CLOSER PROXIMITY TO
LAKE ONTARIO SNOW BAND AND SOME UPSLOPE ENHANCEMENT. AN UPPER
LEVEL DISTURBANCE WILL ENHANCE SNOW SHOWER COVERAGE THIS AFTN AND
THIS EVENING YIELDING MORE WIDESPREAD MVFR CONDITIONS AT THE TAF
SITES AND BRIEF PERIODS OF IFR CONDITIONS. PERIODS OF 1-2SM -SHSN
ARE EXPECTED...ESPECIALLY ACROSS NRN AREAS. THIS ACTIVITY SHOULD BEGIN
TO ABATE AFTER 04Z TUE AS UPR TROUGH PASSES EAST OF THE AREA. SFC
WINDS WILL GENERALLY REMAIN FROM THE SOUTH AT 5-10 KTS THRU
03Z...AND THEN SHIFT NNWWD AROUND 5 KTS OVERNIGHT.
12Z TUESDAY THROUGH FRIDAY...VFR WITH HIGH PRES TUE AND 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.
&&
.CLIMATE...
A SNOW SHOWER WITH APPARENT ORIGINS FROM LAKE ONTARIO PASSED THRU
THE CENTRAL/SRN CHAMPLAIN VALLEY BETWEEN 05-06Z YIELDING A QUICK
HALF INCH OF SNOW OFFICIALLY AT KBTV. THIS WAS THE FIRST MEASURABLE
SNOWFALL OF THE 09-10 SEASON AND TIES THE PREVIOUS RECORD LATEST
DATE FOR THE FIRST SNOW AT BTV. A RECORD EVENT STATEMENT HAS BEEN
SENT. 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. 12/7/2009 ?
1. 12/7/1937 45.1
3. 12/5/1915 54.4
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...MB
NEAR TERM...TABER/MB
SHORT TERM...MB
LONG TERM...BANACOS
AVIATION...BANACOS
CLIMATE...
