000
FXUS61 KBTV 201551
AFDBTV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
1051 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 1050 AM EST THURSDAY...ISSUED A ZONE UPDATE TO MENTION
SCATTERED FLURRIES. LOW LEVEL INSTABILITY HAS PROVIDED SOME
FLURRIES ACROSS THE AREA...DESPITE DEWPOINT SPREAD. HAVE UPDATED
MAX TEMPS USING NAM12...WHICH IS THE ONLY MODEL THAT HAS EVEN THE
SLIGHTEST BIT OF A CLUE FOR TEMPS. OTHERWISE...GOING FORECAST IS
IN GREAT SHAPE AND PREVIOUS DISCUSSION FOLLOWS.
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/NEILES
SHORT TERM...BANACOS
LONG TERM...BANACOS
AVIATION...JMG/JN
