000
FXUS61 KBTV 201141
AFDBTV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
641 AM EST THU NOV 20 2008
.SYNOPSIS...
A CONTINUED COLD STRETCH OF WEATHER WILL PREVAIL ACROSS THE NORTH
COUNTRY THROUGH THE NEXT SEVERAL DAYS. A WEAKENING CLIPPER SYSTEM
PASSING TO OUR SOUTH AND WEST ACROSS WESTERN NEW YORK AND
PENNSYLVANIA WILL BRING CONSIDERABLE CLOUDINESS TO THE REGION TODAY
AND TONIGHT...BUT ONLY MINIMAL CHANCE FOR LIGHT SNOW SHOWERS ACROSS
PORTIONS OF NORTHERN NEW YORK. A REINFORCING COLD FRONT ARRIVES
DURING THE DAY FRIDAY BRINGING THE PROSPECT FOR SCATTERED SNOW
SHOWERS FRIDAY AND INTO EARLY SATURDAY...ESPECIALLY IN MOUNTAIN
LOCATIONS. THE NEXT CHANCE FOR LIGHT TO MODERATE PRECIPITATION
ARRIVES WITH AN UPPER LEVEL DISTURBANCE MONDAY AFTERNOON INTO MONDAY
NIGHT.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 407 AM EST THURSDAY...ABUNDANT MID-LVL CLOUDS ARE EXPECTED TODAY
ASSOCIATED WITH A SHEAR VORTICITY AXIS THAT WILL PIVOT COUNTER-
CLOCKWISE ACROSS THE FORECAST AREA DURING THE DAYLIGHT HRS. SFC
LOW OVER SERN ONTARIO PASSES ACROSS NWRN PA/WRN NY AND WEAKENS
TODAY. IT APPEARS LIGHT SNOW REMAINS SOUTH OF OUR FCST AREA BUT
DID INCLUDE A 20 POP FOR THE NRN ADIRONDACKS AND ST. LAWRENCE
COUNTY NY IN CASE WAA AXIS PIVOTS SLIGHTLY FURTHER NORTH. A
SIGNIFICANT WARM BIAS OCCURRED IN THE MOS TEMPERATURES YESTERDAY.
MAV-MOS WAS 7 DEG TOO WARM ON THE HIGH TEMPERATURE AT BTV
YESTERDAY...AND EXPECT A SIMILAR SITUATION TODAY WITH CLOUD COVER
AS WELL AS SIMILAR 850MB TEMPERATURES AND LIGHT NWLY FLOW. LOOKING
FOR HIGHS IN THE UPR 20S IN THE CHAMPLAIN VLY AND LOW TO MID 20S
ACROSS MUCH OF THE REMAINDER OF THE FCST AREA. HAVE GENERALLY
UNDERCUT MAV-MOS NUMBERS AROUND 5 DEG.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
AS OF 407 AM EST THURSDAY...THE 00Z MODEL SUITE HAS REMAINED CONSISTENT
IN INDICATING YET ANOTHER UPR TROUGH AND AREA OF LOW-LEVEL COLD
ADVECTION SW OF HUDSON BAY WHICH WILL MOVE INTO THE AREA DURING
THE DAY FRIDAY FROM NW-SE. THE CORE OF COLDEST LOW-MID
TROPOSPHERIC AIR IS OVER THE NORTH COUNTRY AT 12Z SATURDAY...WITH
850MB TEMPS OF -16 TO -18C...AND 1000-500MB THICKNESS VALUES
AROUND 500-504 DM. THE LOW-LEVEL COLD ADVECTION AND ASSOCIATED
STEEP LAPSE RATES MAY RESULT IN SCATTERED SNOW SHOWER
ACTIVITY...ESPECIALLY IN WEST AND NORTHWEST FACING MTN LOCATIONS.
THIS WOULD OCCUR FRIDAY AFTN THROUGH EARLY SATURDAY...PERHAPS INTO
SAT AFTN ACROSS ERN/NERN VT. HIGH TEMPERATURES FRIDAY AND SATURDAY
WILL GENERALLY BE IN THE MID 20S IN THE CHAMPLAIN VALLEY AND THE
UPR CT RIVER VALLEY AND LOW 20S ELSEWHERE. NWLY WINDS WILL
CONTINUE AT MODERATE SPEEDS. WELL-MIXED AND STRONGER P-GRADIENT
CONDITIONS SATURDAY SHOULD YIELD NW WINDS 10-15 MPH WITH GUSTS UP
TO 30 MPH. ALSO CONTINUED TREND OF UNDERCUTTING MOS GUIDANCE
TEMPS THROUGH THE PERIOD...ESPECIALLY THE DAYTIME HIGHS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 407 AM EST THURSDAY...THE UPR-LEVEL HGT/THERMAL TROUGH LIFTS
OUT OF THE NERN CONUS SATURDAY NIGHT INTO SUNDAY. SFC RIDGE AXIS
LIKEWISE BUILDS INTO THE AREA FROM THE WEST WITH MODERATING
TEMPERATURES AND PARTLY SUNNY CONDITIONS EXPECTED. PCPN IS NOT
EXPECTED ON SUNDAY. WARM ADVECTION CONTINUES INTO SUNDAY
NIGHT...AND A DEVELOPING WARM FRONT MAY BRING SOME LIGHT SNOW INTO
THE REGION LATE SUNDAY NIGHT INTO EARLY MONDAY. THIS LIGHT SNOW
APPEARS MORE LIKELY ACROSS NRN NY BASED ON PRESENT INDICATIONS.
THEREAFTER...AN AMPLIFYING UPSTREAM UPR TROUGH BRINGS THE
POTENTIAL FOR A FEW INCHES OF SNOWFALL LATE MONDAY THRU MONDAY
NIGHT. THERMAL PROFILES BECOME MARGINAL WITH THIS EVENT...AND MAY
RESULT IN SOME MIXED PCPN IN WRN RUTLAND COUNTY. HAVE EXCLUDED
THIS FROM THE OFFICIAL FCST FOR NOW UNTIL TIMING AND THERMAL
DETAILS BECOME MORE CLEAR. THERE REMAINS CONSIDERABLE UNCERTAINTY
IN THE FORECAST TUESDAY AND WEDNESDAY. GFS TREND HAS BEEN TOWARD A
DEVELOPING COASTAL LOW EAST OF NEW ENGLAND AND A RATHER
SIGNIFICANT TROUGH OVER THE NERN CONUS. THIS IS NOW CLOSER TO THE
ECMWF SOLN. HOWEVER...RUN TO RUN CONTINUITY HAS NOT BEEN
GOOD...TYPICAL OF DEEP CUT-OFF LOW PRESSURE SYSTEMS. AT THIS
POINT...KEPT A 30-40 POP FOR SNOW SHOWERS TUE/WED...PENDING
DETAILS ON HOW COASTAL LOW MIGHT EVOLVE DURING THE TIME PERIOD IN
QUESTION. THERE IS THE POTENTIAL FOR A SIGNIFICANT PRECIPITATION
EVENT DURING THIS PERIOD AND WE WILL CONTINUE TO MONITOR.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
THROUGH 12Z FRIDAY...VFR SKY COND THRU 00Z FRI. SCT-BKN LOW AND
MID CLD DECKS ARE EXPECTED DURING THE COURSE OF THE DAY...BUT WILL
GRADUALLY LWR BY 00Z FRI. WINDS DURING THIS TIME WNW 5-10KTS.
SOME SITES WILL SEE SOME SCT FLURRIES AS CLD DECK LWRS...BUT W/ NO
REDUCTION TO VSBY. AFT 00Z FRI...VFR CLD COVER NOW BKN035-040 FOR
MOST SITES BUT AREAS WILL SEE OCNL BKN020-030 W/ SCT --SW(5-6SM
-SW FOR SLK). WINDS ALL SITES FROM 00Z FRI-12Z FRI WILL REMAIN WNW
10KTS OR LESS. HIR TRRN OBSCD AT TIMES.
AFTER 12Z FRIDAY...THURS NIGHT THROUGH SAT WILL HAVE MVFR CIGS
OVER THE HIGHER TERRAIN WITH TEMPO MVFR IN THE CHAMPLAIN VALLEY
DUE TO LOWER CIGS AND SCATTERED SNOW SHOWERS. SUMMITS SHOULD STAY
OBSCURED DURING MOST OF THIS PERIOD WITH MOIST LOW LEVELS AND
PERSISTENT NW UPSLOPE FLOW. SUNDAY COULD BE THE CLEAREST DAY WITH
A SHORT WAVE RIDGE MOVING INTO THE AREA.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...BANACOS
NEAR TERM...BANACOS
SHORT TERM...BANACOS
LONG TERM...BANACOS
AVIATION...JMG/JN
