FXUS61 KBTV 251247
AFDBTV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
747 AM EST WED NOV 25 2009
.SYNOPSIS...
HIGH PRESSURE OVER THE REGION WILL GIVE WAY TO A WEAK FRONTAL
BOUNDARY...WHICH WILL MOVE ACROSS THE AREA LATE TODAY. HIGH
PRESSURE DOES RETURN FOR THANKSGIVING...FOLLOWED BY A STORM SYSTEM
FOR FRIDAY AND SATURDAY. HIGH PRESSURE RETURNS FOR THE LATTER HALF
OF THE WEEKEND INTO EARLY NEXT MONDAY...FOLLOWED BY YET ANOTHER LOW
PRESSURE SYSTEM ON TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 429 AM EST WEDNESDAY...CLD COVER OVER WESTERN PORTIONS OF
THE CWA THIS MORNING WILL INCR TO REST OF AREA DURING THE DAY AS
WK FRNTL BOUNDARY MVS ACROSS THE CWA. SFC LOW ASSOCIATED W/ THIS
SYSTEM WILL TRACK NE INTO SOUTHERN QUEBEC/ONTARIO DURING THIS
EVENING HRS. MEANWHILE DURING THE DAY CWA WILL SEE SCT/ISO -RW
FROM WK SHORTWAVE AHEAD OF THIS FRNTL BOUNDARY. SOMR ACTIVITY
ALREADY OCCURRING OVER N NY AS EVIDENT ON RADAR LOOP. W/ TEMPS
WELL ABV FREEZING GOING INTO EVENING HRS...EXPECTING PRECIP TO BE
ALL -RW AND WILL CONCENTRATE HIGHEST POPS ACROSS N NY AND NEAR THE
CANADIAN BORDER (BASED ON MDL LOW TRACK)...TAPERING OFF FROM W TO
E TOWARDS MORNING.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
AS OF 429 AM EST WEDNESDAY...SYSTEM MVS N OF THE CWA ON THURSDAY
ALLOWING FOR A FAIRLY NICE DAY FOR THANKSGIVING AS SFC RIDGE
BUILDS OVER THE AREA. CLDS ON INCR BY NGTFALL AS SYSTEM APPROACHES
THE CWA...WHICH MDLS HAVE BEEN FLIP-FLOPPING ON SFC/UPPER LOW
PLACEMENT FOR PAST SEVERAL DAYS. HAVE GONE W/ LATEST CONSENSUS
PLACING CUTOFF LOW JUST SOUTH OF NEW ENG THURSDAY NGT. UPPER LOW
DOES GRAB ONTO FEATURE OFFSHORE AND WILL PIVOT THAT INWARD. THIS
WILL PROVIDE A HIGH QPF EVENT FOR ENTIRE CWA BY MIDDAY FRIDAY W/
UP TO AN INCH OF LIQUID POTENTIAL. MAIN ISSUE FOR THIS EVENT FOR
AFTNOON HRS FRIDAY WILL BE TIMING OF WRAP-AROUND AND SWITCH TO
MORE NORTHERLY FLOW. THIS WILL BEGIN TO DRAG COLDER AIR INTO MOIST
AIRMASS...AND BEGIN CHANGING RW TO SW. THIS WILL AFFECT HIR TRRN
THRU 00Z SATURDAY W/ ONLY AN INCH OF LESS ACCUM POSSIBLE AS
AIRMASS NOT CD ENOUGH FOR WIDESPREAD. SNOWFALL RATIOS WILL DROP TO
NEAR 10:1 AS SNOWFALL PROGRESSES TOWARDS EVENING. DUE TO
UNCERTAINTY IN LOW TRACK...ANY SHIFT OUT TO SEA OR STAYING MORE
INLAND MAJORLY AFFECT PRECIP TYPE/AMT AND CHANGEOVER FROM RAIN TO
SNOW AND WILL HAVE TO BE MONITORED OVER NEXT 24HRS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 500 AM EST WEDNESDAY...WE ARE STILL ON TRACK FOR WINTER
WEATHER TO IMPACT THE FIRST HALF OF THE WEEKEND. AS MENTIONED
ABOVE...THERE IS STILL UNCERTAINTY IN THE FINER...YET
IMPORTANT...DETAILS. BUT DESPITE DIFFERING DETAILS...ALL
SOLUTIONS POINT AT SNOW IN THE HIGHER ELEVATIONS FRIDAY NIGHT AND
SATURDAY. THE CONSENSUS PLACEMENT FOLLOWS MORE CLOSELY WITH THE
ECMWF...WHICH PLACES THE LOW IN THE GULF OF MAINE FRIDAY
NIGHT/SATURDAY MORNING...THEN NORTHEAST TO THE CANADIAN MARITIMES
SATURDAY EVENING. THE ECMWF PLACES THE DEFORMATION ZONE EAST OF
ATLANTIC MOISTURE WILL CONTINUE TO WRAP INTO THE FORECAST
AREA...AND COLD AIR CONTINUES TO BE DRAWN INTO THE REGION AS WELL.
THUS FRIDAY NIGHT...RASN AT HIGHER ELEVATIONS WILL CHANGE TO
SNOW...WITH SNOWFALL RATIO BETWEEN 10:1 AND 12:1. COLD AIR ALOFT
WILL BE SLOW TO MIX TO LOWER ELEVATIONS...SO RANGE OF SNOW
ACCUMULATION WILL BE VERY ELEVATION DRIVEN. MOST VALLEY LOCATIONS
REMAINING IN THE ALL RAIN OR RAIN MIXED WITH SNOW CATEGORY WITH
LITTLE TO NO ACCUMULATION FRIDAY NIGHT.
ON SATURDAY COLD AIR CONTINUES TO WORK INTO THE REGION...WITH SFC
TEMPERATURES EVEN IN THE CPV APPROACHING FREEZING IN THE
AFTERNOON. WITH NORTHWEST FLOW AND CONTINUED WRAP AROUND MOISTURE
IN PLACE...WILL LEAD TO UPSLOPE SNOW SHOWERS. SEVERAL INCHES ARE
POSSIBLE IN AT HIGHER ELEVATIONS AS THE SNOW RATIO CONTINUES TO GROW IN THE
MTNS. IN LOWER ELEVATIONS WE ARE LOOKING AT A DUSTING TO PERHAPS A
COUPLE OF INCHES.
AS IMPORTANT TO IMPACTS WILL BE THE NW WINDS THAT DEVELOP
SATURDAY. WITH A STRONG GRADIENT OVER THE REGION ON THE BACK SIDE
OF THE LOW... WINDS GUSTING TO 30 MPH...STRONGER IN HIGHER
ELEVATIONS...WILL DEVELOP FRIDAY NIGHT AND CONTINUE THROUGH
SATURDAY NIGHT. EXPECT WINDS WILL SOMEWHAT IMPACT VISIBILITY IN FALLING
SNOW.
SATURDAY NIGHT AND SUNDAY...THE CLOSED LOW CONTINUES ITS TRACK
NORTHEAST AND WRAP AROUND SHOWERS WILL BEGIN TO DIMINISH IN THE
NORTHERN MOUNTAINS SATURDAY NIGHT. IN TYPICAL WINTERTIME
FASHION...MOISTURE WILL BE SLOW TO LEAVE THE NORTHEAST
KINGDOM...SO I WILL MAINTAIN THE CHANCE FOR SNOW SHOWERS THERE
THROUGH EARLY SUNDAY. WITH A RIDGE BUILDING OVER THE REGION FROM
THE WEST...ANTICIPATE SOME BREAKS IN THE CLOUDS DEVELOPING SUNDAY
AFTERNOON.
BEYOND SUNDAY THERE IS CONSIDERABLE UNCERTAINTY IN THE FORECAST.
GUIDANCE HAS ESSENTIALLY FLIP FLOPPED IN THE AMPLIFICATION OF THE
500MB PATTERN OVER THE EAST FOR MONDAY. THE GFS PORTRAYS A MORE
ZONAL FLOW WHERE THE ECMWF PROVIDES FOR AN AMPLIFIED RIDGE. THE
LATER IS A MUCH WARMER SOLUTION...WHICH WOULD BRING A RETURN TO
ABOVE NORMAL TEMPS TO THE REGION MONDAY. THE FORECAST REFLECTS A
BLEND OF BOTH SOLUTIONS. BOTH DEPICT A LOW PRESSURE SYSTEM
FORMING IN THE MISSISSIPPI VALLEY SOMETIME LASE SUNDAY NIGHT EARLY
MONDAY MORNING. BOTH ALSO DEPICT AN OPEN GULF MOISTURE
STREAM...THAT WILL BE ADVECTED NORTH INTO THE NORTH COUNTRY
SOMETIME MONDAY OR MONDAY NIGHT. BOTH SOLUTIONS DEPICT THE
POTENTIAL FOR RAIN MOVING INTO THE NORTH COUNTRY FOR TUESDAY.
&&
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
THROUGH 12Z WEDNESDAY...A VARIETY OF FLIGHT CATEGORIES THIS
MORNING...AS CEILINGS AND VIS BEGIN TO LIFT. MOST SITES WILL BE AT
VFR AROUND 15Z. EXCEPTIONS INCLUDE KMPV...WHICH WILL DRIFT BETWEEN
MVFR AND IFR THROUGH 15Z...AND EVENTUALLY LIFT TO VFR AROUND 18Z.
ANOTHER EXCEPTION IS KMSS...WITH WEAK NE FLOW STRATUS WILL BE
SLOW TO LEAVE THE ST. LAWRENCE VALLEY. THERE ARE A FEW LIGHT
SHOWERS MAINLY IN NY...SO VCSH IN KSLK AND KMSS THROUGH 16Z. A
MORE ORGANIZED BAND OF SHOWERS WILL APPROACH NY TAF SITES AROUND
20Z...AND VT TAF SITES BY 23Z. THESE SHOWERS WILL BE LIGHT AND
RAIN. THE WINDOW FOR SHOWERS WILL GENERALLY BE 4 HRS....THEN THE
POTENTIAL INCREASES FOR IFR BR AND STRATUS TO FORM...LASTING
THROUGH 12Z. WINDS WILL GENERALLY BE E OR SE AND LESS THAN 8KT.
WINDS WILL BECOME SOUTHERLY IN THE AFTERNOON AND EVENTUALLY SW
AFTER SUNSET...BUT REMAIN LESS THAN 8 KT.
OUTLOOK 12Z WEDNESDAY THROUGH SUNDAY...
12Z WEDNESDAY THROUGH THURSDAY NIGHT...IFR AND MVFR WITH BR AND
STRATUS THROUGH 13-15Z WED. OTHERWISE GENERALLY VFR. SOME MVFR
-SHRA AT KMSS LATE THURSDAY
FRIDAY...MVFR WITH SCATTERED IFR IN DEVELOPING RAIN.
FRIDAY NIGHT...IFR IN RA...CHANGING TO SN IN MTNS.
SATURDAY...IFR IN SN AT HIGHER ELEVATIONS. RASN ELSEWHERE...CHANGING TO
SN BY EVENING. GUSTY NW WINDS. SUNDAY...BECMG VFR. GUSTY NW WINDS
DIMINISHING.
&&
.CLIMATE...
AS OF 1235 PM MONDAY...ALTHOUGH MOST OF THE NORTH COUNTRY SAW A
LIGHT COATING OF SNOW BACK IN MID OCTOBER...THE IMMEDIATE
CHAMPLAIN VALLEY HAS NOT YET HAD ITS FIRST MEASURABLE SNOW EVENT
OF THE SEASON. FOR BURLINGTON...ON AVERAGE THE FIRST MEASURABLE
SNOW HAPPENS NOVEMBER 6TH. SO WHERE DOES THIS LATE 1ST MEASURABLE
SNOW COMPARE TO THE RECORD BOOKS? 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
5. 11/30/1953 83.6
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...JN
NEAR TERM...JN
SHORT TERM...JN
LONG TERM...AMF
AVIATION...AMF
CLIMATE...
