FXUS61 KBTV 070546
AFDBTV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
1246 AM EST MON DEC 7 2009
.SYNOPSIS...
WEAK HIGH PRESSURE ACROSS THE MID ATLANTIC STATES WILL PROVIDE THE
NORTH COUNTRY WITH PARTLY CLOUDY SKIES...A CHANCE OF MOUNTAIN SNOW
SHOWERS...AND COOL TEMPERATURES TONIGHT. MEANWHILE...A DISTURBANCE
IN THE JET STREAM WINDS ALOFT...ALONG WITH LAKE MOISTURE AND WEAK
SURFACE LOW PRESSURE WILL PRODUCE SCATTERED SNOW SHOWERS ACROSS
NORTHERN NEW YORK AND VERMONT ON MONDAY. SOME LIGHT SNOW
ACCUMULATION WILL BE POSSIBLE WITH NEAR NORMAL TEMPERATURES. A MORE
SIGNIFICANT PRECIPITATION AND WIND PRODUCER WILL IMPACT THE REGION
LATE WEDNESDAY INTO THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 859 PM EST SUNDAY...BASED OFF CURRENT RADAR WHICH SHOWS
DEVELOPING LAKE EFFECTS SNOW SHOWERS OFF LAKE ONTARIO...HAVE
ADJUSTED FORECAST TO INCREASE POPS IN THE PRONE AREAS OF SOUTHEAST
SAINT LAWRENCE COUNTY...AND FAR NORTHERN VERMONT. UPPER TROUGH
NORTH OF THE BORDER COMBINED WITH JUST ENOUGH LOW LEVEL MOISTURE
AND AN IDEAL FETCH OFF LAKE ONTARIO HAS AIDED IN THE DEVELOPMENT
OF LAKE EFFECT SNOW SHOWERS PER RADAR AND WEBCAM TRENDS. CURRENT
WEBCAM AT WANAKENA NY SHOWS LIGHT SNOW FALLING AT THIS TIME...BUT
NOT ACCUMULATING MUCH YET. THUS...THINK OVERALL SNOWFALL AMOUNT
OVERNIGHT WILL GENERALLY BE IN THE DUSTING TO 1 INCH RANGE. HAVE
ALSO ADJUSTED OVERNIGHT TEMPS UP A TOUCH AS INCREASED CLOUD COVER
ACROSS THE REGION SHOULD SLOW THE DECREASE IN TEMPS OVERNIGHT.
PREVIOUS DISCUSSION FROM 245 PM...THE FCST FOCUS THRU TONIGHT WL CHC
FOR MTN SNOW SHOWERS ACRS DACKS/NORTHERN GREEN MTNS FOLLOWED BY
COOL OVERNIGHT TEMPS. FIRST...BIG PICTURE SHOWS FAST WEST TO EAST
FLW ACRS THE NE CONUS WITH NEXT S/W ENERGY ACRS THE CENTRAL HIGH
PLAINS EJECT FROM INTER-MOUNTAIN WEST TROF ATTM. WEAK EMBEDDED 5H
VORT LOCATED NORTH OF GREAT LAKES THIS AFTN...WL BRUSH BY OUR
NORTHERN ZNS TONIGHT...WITH CHC FOR LIGHT SNOW. NAM 12 SLIGHTLY
MORE AGGRESSIVE WITH SFC TO 800MB MOISTURE FROM INTERACTION WITH
NORTHERN LAKES AND PLACES 0.06" OF QPF AT SLK TONIGHT...THEREFORE
WL CONT TO MENTION SCHC/CHC POPS WITH SOME LIGHT ACCUMULATION
POSSIBLE NORTH OF A TUPPER LAKE NY TO MORRISVILLE VT LINE. CRNT
RADAR SHOWS WEAK LAKE EFFECT BAND ACRS THE TUG HILL...WHICH WL
SLOWLY LIFT NORTH TONIGHT AND COULD IMPACT SOUTHERN SAINT LAWRENCE
COUNTY/WESTERN DACKS AFT 06Z. OTHERWISE...GFS SHOWS LIMITED DEEP
LAYER MOISTURE AND VERY WEAK LIFT ASSOCIATED WITH THIS 5H VORT.
TEMPS WL RANGE INTO THE U10S/L20S MTNS/SLK TO M/U 20S MOST VALLEY
LOCATIONS...VERY SIMILAR TO PREVIOUS NITES.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/...
AS OF 245 PM EST SUNDAY...THE BIG QUESTION MONDAY INTO MONDAY NIGHT
WL BTV RECEIVE ITS FIRST MEASURABLE SNOWFALL SINCE APRIL 8TH...A
STREAK OF OVER 240 DAYS. FEEL PRETTY STRONGLY ABOUT THE STREAK
ENDING BY 7 PM MONDAY EVENING...BASED ON CRNT OBS AND TRENDS
UPSTREAM OVER THE HIGH PLAINS. WATER VAPOR PLACES ELONGATED 5H
VORT ACRS CENTRAL HIGH PLAINS TODAY WITH GLD REPORTING 1SM IN -SN
UNDER THIS FEATURE. THIS SYSTEM WL RACE NE TWD THE OHIO
VALLEY/GREAT LAKES BY MONDAY. THE COMBINATION OF GOOD 5H
PVA...LATEST GFS/NAM SHOWING A 3 TO 6 HR WINDOW BTWN 18Z-00Z OF
GOOD 850-500MB Q-VECTOR CONVERGENCE AND LFQ OF 250MB JET OF 140
KNTS WL PRODUCE SOME LIGHT ACCUMULATING SNOWFALL ACRS THE NORTH
COUNTRY ON MONDAY. FURTHERMORE SOUNDINGS SHOW DEEP MOIST LAYER
ADVECTING FROM WEST TO EAST ACRS OUR CENTRAL/NORTHERN ZNS ON
MONDAY...WHICH SHOWS GOOD MOISTURE IN THE FAVORABLE SNOW GROWTH
REGION. SEVERAL FACTORS AGAINST ACCUMULATING SNOWFALL AT BTV WL BE
SOUTH TO SOUTHWEST WINDS OF 10 TO 20 KNTS...CREATING SOME
DOWNSLOPE DRYING...BUT SPEEDS ARE WEAK AND SHOULD LIMIT IMPACTS.
FURTHERMORE...BL TEMPS IN THE CPV WL WARM INTO THE MID 30S BEFORE
ARRIVAL OF LIGHT SNOW...WHICH COULD PRODUCE SOME MELTING BEFORE
THE SNOW STARTS ACCUMULATING. OTHERWISE...FEEL THESE THREATS WL BE
MINIMAL...AND SOME LIGHT ACCUMULATION OF A TRACE TO 1 INCH WL BE
POSSIBLE...EVEN AT BTV. GIVEN...TIMING OF SYSTEM DURING THE
EVENING COMMUTE AND SOME MELTING DUE TO WARM BL TEMPS....ROAD
SURFACES COULD BECM VERY SLIPPERY AS THE SUNSETS MONDAY EVENING.
BOTH GFS/NAM SHOW A SHARP 850 TO 500MB MOISTURE GRADIENT FROM
SOUTH TO NORTH ACRS OUR CWA...THEREFORE NOT EXPECTING MUCH
ACCUMULATION OVER RUTLAND/WINDSOR COUNTIES...WHERE THEY SAW
SEVERAL INCHES ON SATURDAY NIGHT. 85H TEMPS AND 2M NAM TEMPS
SUPPORT HIGHS IN THE M30S VALLEYS TO U20S/L30S MTNS ZNS ON MONDAY.
BY MONDAY NIGHT...SYSTEM WL QUICKLY EXIT FA WITH LIGHT SNOW ENDING
FROM WEST TO EAST ACRS OUR NORTHERN/CENTRAL ZNS. WL MENTION HIGHEST
POPS ACRS THE DACKS ASSOCIATED WITH LAKE ENHANCED SNOW SHOWERS AND
NORTHERN GREENS WITH WEAK UPSLOPE SIGNATURE. BY 06Z...WINDS BECM
NORTHERLY AND BEST LLVL CONVERGENCE/LIFT ASSOCIATED WITH LAKE
EFFECT SNOW WL BE WELL SOUTH OF OUR CWA NEAR KSYR. TEMPS WITH FRESH
SNOW COVER WL FALL INTO THE M/U 10S MTNS TO L/M 20S ELSEWHERE.
TUES-TUES NIGHT...MID/UPPER LVL HGHTS BEGIN TO INCREASE AS RIDGE
BUILDS AHEAD OF DEVELOPING MIDWEST TROF AND SFC LOW PRES. THE
COMBINATION OF BUILDING HGHTS AND SFC HIGH PRES OVERHEAD...WL
PRODUCE PARTLY SUNNY SKIES ACRS THE MTNS WITH MOSTLY SKIES SKIES
ACRS THE CPV/SLV ON TUES. PROGGED 85H TEMPS NEAR -10C AND 925MB
TEMPS AROUND -8C WL SUPPORT HIGHS ONLY IN THE M20S MTNS TO L30S
VALLEYS. WEAK UPSLOPE FLW AND LEFTOVER SHALLOW MOISTURE...MAY
PRODUCE A FEW FLURRIES ACRS THE HIGHER TRRN. BY TUES NIGHT...SFC
HIGH SHIFTS INTO NORTHERN MAINE AND SOUTH TO SOUTHEAST FLW DEVELOPS
WITH INITIAL 5H VORT AND ASSOCIATED LLVL WAA WL PRODUCE CLOUDS FROM
SW TO NE ACRS OUR CWA AFT 06Z. BASED ON PROGGED 850 TO 500MB
MOISTURE FIELDS AND SOME 700 TO 500 MB UVVS APPROACHING OUR SW ZNS
BY 12Z WEDS...WL MENTION CHC POPS. 1000 TO 500MB THICKNESS VALUES
AND LLVL THERMAL PROFILES SUPPORT ALL SNOW THRU 12Z WEDS....BUT BEST
LIFT/MOISTURE WL OCCUR AFT 12Z WEDS...THEREFORE WL MENTION JUST CHC
POPS TUES NIGHT AFT 06Z. GIVEN INCREASE CLOUDS...EXPECT A SHARP SW
TO NE THERMAL GRADIENT ACRS OUR CWA ON TUES NIGHT...WITH TEMPS WEST
OF THE GREEN MTNS INCREASING AFTER 06Z.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 245 PM EST SUNDAY...MOST SIGNIFICANT SYSTEM IN THE 7-DAY
FCST PERIOD TO AFFECT THE AREA WED INTO WED NIGHT WITH WIDESPREAD
PCPN AND AN ENHANCED WIND THREAT. LATEST OPERATIONAL AND ENSEMBLE
PROGS INCLUDING THIS MORNINGS EURO RUN CONTINUE TO SHOW IMPRESSIVE
SUB-980 MB SFC LOW BOMBING OUT AS IT TRACKS NORTHEASTWARD INTO THE
GREAT LAKES ON WEDNESDAY. VERY IMPRESSIVE HEIGHT/PRESSURE FALLS
DURING DAY ALONG WITH ROBUST WAA/ISENTROPIC LIFT SHOULD ENSURE
WIDESPREAD PCPN OVERSPREADS THE REGION FROM THE SOUTHWEST DURING
THE DAY. A QUICK LOOK AT 925/850 MB TEMP PROGS ARGUES THAT PTYPE
SHOULD BEGIN AS ALL SNOW...THEN TRANSITION EITHER TO A MIX OR RAIN
ACROSS THE SOUTH/SOUTHWESTERN PORTIONS OF THE FA DURING THE
AFTERNOON/EARLY EVENING. AREAS ACROSS NERN VT HOWEVER MAY REMAIN
ALL SNOW. THIS APPEARS REASONABLE GIVEN LATEST PROGS SHOWING
TRIPLE POINT LOW TRACKING NEARLY ATOP CWA...ESSENTIALLY SHUNTING
BEST INTRUSION OF WARMER AIR ALOFT MORE EAST THAN NORTH THROUGH
TIME. THAT SAID WILL LEAN MORE TOWARD MILDER ECMWF DEPICTION OF
MID LVL WARMING DURING THIS PERIOD WHICH TYPICALLY HANDLES THESE
SCENARIOS A TAD BETTER THAN GFS AT THIS TIME RANGE.
ADDITIONALLY...WITH CORE OF 60-70KT SOUTHEASTERLY JET CORE AT 850
MB TRAVERSING THE REGION ALSO FEEL LIKELIHOOD IS INCREASING FOR
GUSTY TO PERHAPS STRONG SERLY GAP WINDS ACROSS THE HIGHER
ELEVATIONS ALONG THE WESTERN SLOPES OF THE GREENS. SOME
UNCERTAINTY HOWEVER ON DEGREE OF BNDRY LYR MIXING AND HEIGHT OF
LOW LEVEL INVERSION...ESP WITH STRONGEST WINDS OCCURRING DURING
TIME OF HEAVIEST PCPN. NONETHELESS...ENOUGH OF A THREAT TO BEGIN
MENTION OF GUSTY WINDS IN THESE LOCALES.
BY WEDNESDAY NIGHT...BEST DYNAMICAL SUPPORT CONTINUES TO PUSH
NORTHEAST ACROSS THE AREA WITH SNOW AND/OR MIXED PCPN LIKELY
TAPERING OFF IN INTENSITY OVERNIGHT AS ENHANCED DRY SLOT SURGES INTO
THE REGION...ESP SOUTH. SFC COLD FRONT THEN PUSHES INTO THE REGION
LATER AT NIGHT...ESP NRN NY ZONES. TRICKY TIMING ON THIS BUT WILL
OFFER NEAR STEADY TEMPS OVERNIGHT EAST...AND READINGS FALLING LATE
WEST. ADDITIONAL WIND CONCERNS HERE AS WELL AS EVIDENCE MOUNTING
FOR A PRONOUNCED POST-FRONTAL SOUTHWESTERLY/WESTERLY WIND
SURGE...ESP ACROSS OUR NRN NY ZONES WHERE INITIAL PROGS OFFER
STRONG MECHANICAL MIXING AND GUSTS TO NEAR 50KTS OR SO. EVEN ACROSS
VT MEAN MIXED WESTERLY FLOW TO 40KT INDEED POSSBL...ESP ACROSS
CHAMPLAIN/CT RVR VALLEY ZONES WHERE DOWNSLOPING ENHANCEMENT MAY
OCCUR.
THEREAFTER...OVERALL FCST WILL TREND COLDER AND GENERALLY DRIER FOR
MUCH OF THE AREA...THOUGH WITH STRONG CAA ON WESTERLY FLOW AND MEAN
850 TEMPS FALLING BELOW -15C LAKE EFFECT AND LIGHTER OROGRAPHICALLY
ENHANCED SHSN WILL BE A GOOD BET. THUS WILL OFFER LOW CHC POPS IN
THE DEEPER VALLEYS...AND HIGH CHC TO LOW LIKELY POPS ACROSS FAVORED
LOCALES...ESP IN THE LK ONTARIO SNOWBELTS OF SRN ST LAWRENCE/SRN
FRANKLIN COUNTIES. AGAIN...A COLD STRETCH ON TAP HERE WITH READINGS
AVERAGING 5-10 DEGREES BELOW NORMAL WHICH WILL FEEL A TAD WORSE
GIVEN BLUSTERY WINDS AND RECENT STRETCH OF MILD WEATHER.
&&
.AVIATION /06Z 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 MUCH OF MONDAY. THRU 16Z...CEILINGS WILL GENERALLY REMAIN
IN THE VFR CATEGORY...EXCEPT LOCALLY 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 YIELDING MORE WIDESPREAD
MVFR AT THE TAF SITES AND BRIEF PERIODS OF IFR CONDITIONS. PERIODS
OF 1-2SM -SHSN ARE FCST. 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.
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...
MORE INTERESTING SNOWFALL DATA FOR BURLINGTON...OUR LAST
MEASURABLE SNOWFALL OCCURRED ON APRIL 8TH...WHICH IS 242 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 SNOW ACCUMULATION POSSIBLE
MONDAY AND AGAIN ON WEDS.
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/?/2009 ????
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...TABER
NEAR TERM...TABER/LAHIFF
SHORT TERM...TABER
LONG TERM...JMG
AVIATION...BANACOS
CLIMATE...TEAM BTV
