FXUS61 KBTV 121127
AFDBTV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
627 AM EST FRI MAR 12 2010
.SYNOPSIS...
A RIDGE OF HIGH PRESSURE ACROSS THE GULF OF MAINE WILL RESULT IN
VARIABLY CLOUDY BUT DRY CONDITIONS TODAY. A LARGE AND SLOW-MOVING
AREA OF LOW PRESSURE ACROSS THE MISSISSIPPI VALLEY WILL GRADUALLY
MOVE TO THE EASTERN SEABOARD...WITH INCREASING CHANCES FOR RAIN
ACROSS OUR REGION SATURDAY NIGHT INTO SUNDAY. THIS SYSTEM ALSO HAS
THE POTENTIAL TO BRING MODERATELY STRONG WINDS TO THE WESTERN SLOPES
OF THE GREEN MOUNTAINS LATE SATURDAY THROUGH SUNDAY MORNING.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 256 AM EST FRIDAY...SFC ANTICYCLONE EXTENDING FROM NRN QUEBEC
INTO THE GULF OF MAINE IS DRAWING RELATIVELY COOL...MODIFIED MARINE
AIR MASS INTO CENTRAL/ERN VT TODAY WITH VARIABLY CLOUDY CONDITIONS
EXPECTED THROUGHOUT THE DAYLIGHT HRS ALONG AND EAST OF THE GREENS
MTNS. FROM THE CHAMPLAIN VALLEY WWD...SOMEWHAT DIFFERENT STORY
WITH SWLY LOW-LEVEL TRAJECTORIES LESS INFLUENCED BY ANTICYCLONIC
FLOW. THIS IS INDUCING A PATTERN OF LOW-LEVEL ISENTROPIC ASCENT
WITH ISOLD -RW ACTIVITY ACROSS SRN SECTIONS OF THE FCST AREA AS OF
08Z. THIS ACTIVITY WILL LIKELY DIMINISH BY 12Z. DIFFERENT
AIR STREAMS IMPACTING THE FA TODAY SUGGEST HIGH TEMPERATURES
SHOULD BE WARMER AS ONE PROGRESSES FURTHER WEST ACROSS THE CWA
THIS AFTN. LOOKING FOR A RATHER LARGE DISPARITY IN AFTERNOON
TEMPERATURES...RANGING FROM THE LOW 40S ALONG THE ERN SLOPES OF
THE GREEN MTNS /CONTRIBUTED BY ADIABATIC/UPSLOPE COOLING/...TO THE
LOW AND POSSIBLY MID 50S IN THE CHAMPLAIN VALLEY...AND NEAR 60F IN
FAR WRN ST. LAWRENCE COUNTY NY. MEANWHILE...BUILDING 700-500MB
RIDGE ORIENTED FROM SE-NW ACROSS THE FORECAST AREA WILL BE
EFFECTIVE IN KEEPING PCPN SHIELD OVER WRN PA TO OUR SW. WHILE LOW
CLOUDS WILL BE MOST PREVALENT IN THE ERN CWA...MID AND HIGH CLOUDS
WILL BE MORE WIDESPREAD ACROSS SWRN SECTIONS ON EDGE OF RIDGE
AXIS. WINDS ACROSS MOST SECTIONS WILL BE SELY AT 10-15 MPH
TODAY...EXCEPT NELY THIS MORNING WITH P-GRADIENT ORIENTED ALONG
THE ST. LAWRENCE RIVER VALLEY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
AS OF 256 AM EST FRIDAY...FAVORED BLEND OF 00Z NAM12 AND 00Z ECMWF
DURING THE FORECAST PERIOD. LOOKING FOR 700-500MB RIDGE AXIS TO
GRADUALLY SHIFT NEWD ALLOWING FOR DEFORMATION BAND RAINFALL TO
SLOWLY WORK TOWARD SRN EDGE OF THE CWA TONIGHT. DEFORMATION RAIN
BAND WILL BE EXTREMELY CLOSE TO OUR CWA BORDER...AND HAVE
INDICATED 30-40 POPS ALONG THE CWA EDGE AFTER 06Z TONIGHT. ACROSS
CENTRAL AND NRN SECTIONS...SHOULD REMAIN DRY. IF IT CAN
PRECIPITATE ACROSS THE NRN ADIRONDACKS AND RUTLAND AND WINDSOR
COUNTIES LATE TONIGHT...VERTICAL TEMPERATURE PROFILES MARGINALLY
SUPPORT A IP/ZR MIX...ESPECIALLY IN THE 1000-2000 FT ELEVATIONAL
BAND. HAVE CONTINUED THIS IN THE FORECAST...BUT WITH LOW POPS
FORECAST...NOT ENOUGH TO INCLUDE IN THE HWO AT THIS POINT. WILL
CONTINUE TO MONITOR TRENDS. LOWS OVERNIGHT WILL MAINLY BE IN THE
LOW TO MID 30S...EXCEPT MID-UPR 20S POSSIBLE FAR NERN VT WITH
BINOVC POSSIBLE CLOSER TO MID-LEVEL RIDGE AXIS.
ON SATURDAY...A DEEPER-LAYER SELY FLOW DEVELOPS ACROSS THE SRN FCST
AREA...ESPECIALLY BY AFTERNOON...AS SFC LOW TRACKS INTO THE
MID-ATLANTIC REGION. AGAIN...CWA IS ON NRN FRINGE OF POTL PCPN AREA
AND KEPT POPS IN CHANCE CATEGORY /30-40 PERCENT ACROSS RUTLAND AND
WINDSOR COUNTIES...AND LOWER TO THE NORTH /AROUND 10 PERCENT FROM
BTV NWD/. WINDS WILL INCREASE ALONG THE WRN SLOPES OF THE GREEN
MTNS WITH STRENGTHENING GRADIENT FLOW...SELY AT 15-25 MPH NEAR
KRUT WITH GUSTS TO 35 MPH LATE IN THE DAY. AFTN HIGHS WILL MOSTLY
BE IN THE MID TO UPR 40S...EXCEPT LWR 50S ACROSS THE ST. LAWRENCE
VALLEY OF NY FURTHER REMOVED FROM THE LOW-LEVEL CYCLONIC
CIRCULATION.
SATURDAY NIGHT EXPECT POPS TO INCREASE MORE SIGNIFICANTLY WITH NWD
PIVOT OF WARM CONVEYOR BELT FROM THE ATLANTIC OCEAN ACROSS CENTRAL
NEW ENGLAND INTO OUR SRN FCST AREA. WILL CONTINUE WITH MODERATELY
STG SELY WINDS 20-30 MPH...WITH GUSTS 30-40 MPH ACROSS S-CENTRAL VT
AND THE WRN SLOPES OF THE GREEN MTNS IN PARTICULAR. QPF AMTS WILL
BE HIGHEST ALONG THE ERN SLOPES OF THE GREEN MTNS AIDED BY
OROGRAPHIC ASCENT. TAKEN BLEND OF SREF/ECMWF/NAM...LOOKING FOR A
QUARTER TO THIRD OF AN INCH OVERNIGHT ALONG THE EAST FACING SLOPES
OF THE GREEN MTNS...AND POSSIBLY ACROSS THE EAST FACING SLOPES OF
THE NRN ADIRONDACKS AS WELL. AGAIN PRESENTED WITH THERMODYNAMIC
SOUNDINGS MARGINAL FOR IP/ZR MIX AT 1000-2000 FT ELEVATIONS IN
CENTRAL/ERN VT AND THE DACKS. HAVE MENTIONED RAIN LIKELY WITH A
CHANCE OF FREEZING RAIN AND SLEET IN THESE LOCATIONS DURING SATURDAY
NIGHT. WITH RELATIVELY WARM GROUND...LIKELY NOT A SIGNIFICANT TRAVEL
CONCERN BUT SOME MIXED P-TYPE IS WORTH NOTING.
ON SUNDAY...MAINLY CLOUDY WITH CONTINUED RAINFALL AS WARM
CONVEYOR BELT PIVOTS NWD INTO NRN VT AND GRADUALLY WEAKENS PER 00Z
ECMWF. TOTAL RAINFALL COULD APPROACH 1 INCH ACROSS SERN VT...WITH
GENERALLY 0.30 TO 0.70" ELSEWHERE ACROSS THE FA. SELY WINDS SHOULD
GRADUALLY DIMINISH ACROSS THE WRN SLOPES OF THE GREEN MTNS DURING
THE AFTN HRS. HIGHS WILL MAINLY BE IN THE 40S.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 400 AM EST FRIDAY...THE LONG TERM WX CHALLENGE WL BE CHC FOR
POPS SUNDAY NIGHT INTO MONDAY ASSOCIATED WITH DEPARTING MID/UPPER
LVL SYSTEM...FOLLOWED BY TEMPS FOR NEXT WEEK. WL TREND TWD ECMWF
FOR THIS PACKAGE...BASED ON BETTER RESULTS WITH DEEP CLOSED
CYCLONIC CIRCULATIONS AND PREVIOUS PERFORMANCES THIS WINTER. GIVEN
POSITION OF DEEP CIRCULATION AND WEAK EMBEDDED 5H VORTS
INTERACTING WITH WELL ESTABLISHED EASTERLY FLW...WL CONT TO MENTION CHC POPS
SUNDAY NIGHT INTO MONDAY ACRS OUR EASTERN/SOUTHERN ZNS. LLVL
THERMAL PROFILES SUGGEST MAINLY RAIN...WITH SOME VERY HIGH MTN
SNOW/SLEET POSSIBLE LATE SUNDAY NIGHT. OVERALL...DYNAMICS AND
MOISTURE WL BE DECREASING...THEREFORE QPF AMOUNTS WL BE LIGHT. BY
MONDAY AFTN...850 TO 500MB MOISTURE DECREASES FROM NW TO SE ACRS
OUR CWA...WITH INCREASING AMOUNTS OF SUN EXPECTED. THIS COMBINED
WITH PROGGED 85H TEMPS NEAR 0C...SUPPORT HIGHS NEAR 50F MOST
LOCATIONS. WEAK BACKDOOR FRNT WL PUSH ACRS CWA ON TUES...WITH BEST
850 TO 700MB MOISTURE/UVVS STAYING NORTH OF CWA...WL CONT TO
MENTION SCHC POPS AND SLIGHTLY COOLER TEMPS ON WEDS.
OVERALL...BEST 85H CAA AND LARGEST DROP IN 1000 TO 500 MB
THICKNESS VALUES WL STAY NORTH OF CWA. PROGGED 85H TEMPS BTWN -1C
AND -3C ON WEDS SUPPORT HIGHS BACK IN THE 40S...BUT TEMPS ARE
EXPECTED TO REBOUND BACK INTO THE L50S BY THURS. OVERNIGHT LOWS WL
RANGE FROM THE 20S TO L30S MOST LOCATIONS...WHICH IS 5 TO 8
DEGREES ABOVE NORMAL. BOTH ECMWF/GFS SHOW DEVELOPMENT OF A DEEPER
MID/UPPER LVL TROF LATE THURS INTO FRIDAY...WHICH MAY PRODUCE SOME
LIGHT PRECIP AND COOLER TEMPS BY WEEKS END. HOWEVER...STILL PLENTY
OF UNCERTAINTY WITH REGARDS TO DEVELOPMENT OF TROF AND AMOUNT OF
LLVL CAA...WL TREND WARMER FOR NOW.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
THROUGH 12Z SATURDAY...VFR CONDITIONS WL CONT AT ALL TAF SITES
TODAY...EXCEPT A BRIEF PERIOD OF MVFR CONDITIONS AT SLK DUE TO LOW
CIGS. OTHERWISE...SOUNDINGS CONT TO SHOW SOME MOISTURE BTWN SFC-
700MB THRU 00Z TODAY...ESPECIALLY ALONG AND EAST OF THE
CPV...ASSOCIATED WITH MOIST EAST/SOUTHEAST FLW. WL CONT TO MENTION
BKN-OVC CIGS BTWN 035-060 AT RUT/PBG/BTV/MPV/SLK...WITH SOME CLRING
EXPECTED LATE DUE TO DEVELOPING RIDGE AND INCREASE SUBSIDENCE.
OTHERWISE...EXPECT SOUTHEAST WINDS OF 8 T0 14 KNTS WITH GUSTS TO
20 KNTS TO DEVELOP AT RUT/BTV BY 16Z TODAY. MOISTURE PROGGS
TONIGHT SUPPORT A SCATTERED DECK AROUND 050KFT AFT 04Z WITH A BKN
DECK BTWN 120-150KFT AT MOST SITES. WINDS WL REMAIN FROM THE
EAST/SE AT 4 TO 8 KNTS.
OUTLOOK 12Z SATURDAY THROUGH TUESDAY...VFR CONDITIONS 12Z SAT THRU
06Z SUN WITH SFC RIDGE IN PLACE. VFR/MVFR CONDITIONS DEVELOPING BY
12Z SUNDAY WITH BAND OF RAIN SHOWERS AND LOWERING
CIGS...ESPECIALLY AT MPV/RUT SITES. IMPROVING CONDITIONS BY 12Z
MONDAY WITH VFR CONDITIONS PREVAILING ASSOCIATED WITH MID/UPPER
LVL RIDGE OF HIGH PRES.
&&
.CLIMATE...
QUITE A REMARKABLE STRETCH OF MILD WEATHER ACROSS THE NORTH
COUNTRY DURING THE PAST MONTH PLUS. AT BURLINGTON...THE DAILY AVERAGE
TEMPERATURE HAS BEEN AT OR ABOVE THE 30-YEAR CLIMATOLOGICAL MEAN
FOR 32 CONSECUTIVE DAYS...DATING BACK TO FEBRUARY 7TH. THE
AVERAGE TEMPERATURE FOR MARCH THUS FAR IS 35.0F...OR 8.4F ABOVE
NORMAL. THE AVERAGE TEMPERATURE FOR FEBRUARY FINISHED AT 26.0F OR
6.1F ABOVE NORMAL.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...BANACOS
NEAR TERM...BANACOS
SHORT TERM...BANACOS
LONG TERM...TABER
AVIATION...TABER
CLIMATE...
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