FXUS61 KBTV 221928
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
228 PM EST TUE DEC 22 2009

.SYNOPSIS...
MOISTURE FROM THE CANADIAN MARITIMES WILL INTERACT WITH AN UPPER 
LEVEL DISTURBANCE MOVING SOUTHEASTWARD ACROSS THE NORTH COUNTRY TO 
BRING A PROLONGED PERIOD OF LIGHT SNOW TO THE NORTHERN MOUNTAINS 
AND WESTERN SLOPES OF THE GREEN MOUNTAINS TONIGHT THROUGH WEDNESDAY 
NIGHT. SOME PERIODS OF LIGHT SNOW ARE ALSO POSSIBLE IN THE NORTHERN 
VALLEYS...MAINLY LATE TONIGHT AND THROUGH THE DAY WEDNESDAY. 
TEMPERATURES WILL REMAIN BELOW NORMAL THROUGH WEDNESDAY...AND THEN 
MODERATE TO AROUND FREEZING FOR HIGHS THURSDAY UNDER MAINLY SUNNY 
SKIES. NEXT CHANCE FOR MIXED PRECIPITATION ARRIVES LATE FRIDAY NIGHT 
INTO SATURDAY. 

&&

.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 222 PM EST TUESDAY...AN INTERESTING WEATHER SCENARIO EXPECTED 
TONIGHT AND WEDNESDAY. UPPER LOW OVER THE OTTAWA VALLEY/SERN
ONTARIO THIS AFTERNOON WILL CONTINUE TO SHIFT SLOWLY
SOUTHEASTWARD...AND WILL BE CENTERED EAST OF THE CT RIVER VALLEY
BY 12Z WEDNESDAY. THE UPPER LOW ITSELF IS NOT ASSOCIATED WITH MUCH
IN THE WAY OF PRECIPITATION. HOWEVER...INTERACTION OF ATLANTIC
MOISTURE AND ELY 700MB FLOW ACROSS NRN MAINE AND SRN QUEBEC WILL
EVENTUALLY WRAP AROUND THE UPPER LOW AND SWWD INTO THE NORTH
COUNTRY OVERNIGHT. DEFORMATION BAND AND ASSOCIATED 1-3SM LIGHT
SNOW OCCURRING AT 19Z ACROSS FAR N-CENTRAL/NERN VT WILL REMAIN
STATUS QUO UNTIL AROUND 04Z TONIGHT. THEREAFTER...DO EXPECT THE
CLEAR SKIES FROM BTV SWD TO BE REPLACED BY INCREASING CLOUDS WITH
WRAPAROUND FROM THE NORTH AND DEVELOPMENT OF LIGHT SNOW ACTIVITY
OVERNIGHT. BASED ON NAM AND GFS MODEL SOUNDINGS...ACTUALLY SHOULD
SEE LOW-LEVEL WAA FROM THE NORTH AND EAST AS CLOSED UPR LOW
PASSES. SOME SIMILARITIES TO THE MARCH 4 2006 CASE WHERE
OROGRAPHIC BLOCKING AND LOW INVERSION HEIGHT NEAR RIDGE TOP LEVEL
CAUSED SIGNIFICANT SNOWFALL ACROSS THE ERN CHAMPLAIN VALLEY AND
WRN SLOPES OF THE GREEN MTNS. MOISTURE AND DENDRITE GROWTH NOT
QUITE AS OPTIMAL LATE TONIGHT/WEDNESDAY AS THAT EVENT...BUT DO
EXPECT SOME OROGRAPHIC ENHANCEMENT BEGINNING AFTER MIDNIGHT
TONIGHT AND CONTINUING THROUGH MOST OF WEDNESDAY ACROSS THE
CENTRAL/NRN GREEN MTNS AND ADJACENT WRN SLOPES. POPS REFLECT
OROGRAPHIC NATURE OF SNOW TONIGHT...WITH 70-80 POPS NEAR THE NRN
GREENS AND ONLY AROUND 20 PERCENT IN THE VALLEYS OF WRN RUTLAND
COUNTY AND ERN WINDSOR COUNTY. SNOW RATIOS SHOULD BE
LARGE...ASSUMING 20:1 TO GET SNOWFALL AMTS OF 2-5" THROUGH 00Z THU
ACROSS THE CENTRAL/NRN GREENS AND LOCALLY TO 6" NEAR JAY PEAK. IN
THE CHAMPLAIN VALLEY...NOT MUCH ON THE NY SIDE BUT 1-3" POSSIBLE
FROM BTV EWD INTO THE FOOTHILLS. LIKEWISE...EXPECTING 1-3" IN THE
NRN ADIRONDACKS...FURTHER REMOVED FROM BETTER ADVECTION OF
ATLANTIC MOISTURE. BEST POTENTIAL - BUT STILL LIGHT SNOW -
ANTICIPATED FROM 06Z TONIGHT THROUGH 18Z THURSDAY. BECAUSE TOTAL
SNOWFALL AMOUNTS ARE STRETCHED OUT OVER A 24 HR PERIOD...RATES AND
AMTS BECOME TOO MARGINAL TO WARRANT A SNOW ADVISORY.
ALSO...DRY/POWDERING NATURE OF THE SNOW TENDS TO MITIGATE TRAVEL
IMPACTS. WILL HIGHLIGHT IN THE HAZARDOUS WEATHER OUTLOOK FOR NOW
AND MENTION CENTRAL/NRN GREENS AND WEST SLOPES AS HIGHEST SNOWFALL
POTENTIAL.

LOWS TONIGHT WILL GENERALLY BE IN THE 0 TO 10F RANGE...AND REBOUND 
INTO THE LOWER 20S FOR HIGHS TOMORROW. 

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
AS OF 222 PM EST TUESDAY...CLOSED 500MB LOW OVER ERN MA AT 00Z THURSDAY 
SHIFTS SOUTHEAST OF NEW ENGLAND WITH MID-LEVEL HEIGHT RISES NOTED
OVER OUR FORECAST AREA DURING WEDNESDAY NIGHT. A HIGHLY AMPLIFIED
RIDGE AXIS AT THE SFC AND ALOFT BUILDS OVER THE NORTH COUNTRY
DURING THURSDAY AND THURSDAY NIGHT. LOOKING FOR MTN SNOW SHOWER
ACTIVITY ACROSS THE NRN ADIRONDACKS AND NRN VT TO GENERALLY COME
TO AN END DURING WEDNESDAY NIGHT. AN ADDITIONAL DUSTING TO AN INCH
IS POSSIBLE ACROSS NRN AREAS MAINLY BEFORE MIDNIGHT...WITH JUST A
FEW FLURRIES THEREAFTER AS MID-LEVEL SUBSIDENCE INCREASES IN
EARNEST. WITH CORE OF COLDEST MID-LEVEL TEMPERATURES SHIFTING EAST
OF NEW ENGLAND...THURSDAY MORNING LOWS SHOULDN/T BE QUITE AS COLD
WITH LOWS MAINLY IN THE TEENS.

SKIES SHOULD BECOME PARTLY TO MOSTLY SUNNY ON THURSDAY WITH THE 
DEEP-LAYER RIDGE MOVING INTO PLACE. LOOKING AT 850MB TEMPS ALSO 
MODERATING TO AROUND -2C BY AFTN...AND WITH SUNSHINE SHOULD SEE HIGH 
TEMPS IN THE VALLEYS AROUND 32F ON THURSDAY. SHOULD BE A NICE WINTER 
DAY WITH LIGHT WIND CONDITIONS. TEMPERATURES SHOULD FALL BACK INTO 
THE TEENS THURSDAY NIGHT UNDER MOSTLY CLEAR SKIES AND LIGHT AND 
VARIABLE WINDS.   

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 222 PM EST TUESDAY...PRIMARY FOCUS DURING EXTENDED PORTIONS OF 
FCST WILL BE BROAD SCALE LIFT AND ASSOC PCPN ASSOC W/OCCLUDED
FRONTAL BNDRY PUSHING NORTHEASTWARD ACROSS THE AREA SAT/SAT NIGHT.
PRIOR TO THIS HIGH PRESSURE WILL BE IN THE PROCESS OF SLOWLY
RETREATING EASTWARD DURING FRI/FRI NIGHT UNDER INCREASING
SOUTH/SOUTHEASTERLY FLOW. WILL KEEP THINGS MAINLY DRY HERE WITH
AMPLE SUN FRIDAY GIVING WAY TO INCREASING CLOUDS FRI NIGHT. WILL
MAINTAIN PRIOR FCSTS IDEA OF CHC POPS LATER FRIDAY NIGHT ACROSS
OUR SWRN ZONES AS FRONTAL BNDRY APPROACHES...BUT MOST AREAS SHOULD
REMAIN ESSENTIALLY DRY OVERNIGHT. MOS GUIDE MINS TOO COOL
HERE...TYPICAL IN NOCTURNAL RETURN FLOW REGIMES AND HAVE LEANED
CLOSER TO RAW GFS MODEL OUTPUT HERE.

FRONTAL ZONE THEN PUSHES UP AND ACROSS THE REGION SAT/SAT NIGHT WITH 
WIDESPREAD ALBEIT FAIRLY LIGHT PCPN. PCPN LIKELY TO BEGIN AS A 
PERIOD OF SNOW...THOUGH WITH SUCH STRONG SOUTH/SERLY WIND FIELDS 
ALOFT (50-70 KT) HARD TO SEE THAT THIS WILL BE ANYTHING BUT BRIEF AS 
MILDER AIR RUSHES IN ALOFT. THUS WILL ADVERTISE PCPN CHARACTER 
TRANSITIONING TO A MIX AND/OR LIGHT RAIN BY LATER IN THE DAY ON 
SATURDAY INTO SATURDAY NIGHT BEFORE COLDER AIR PUSHES IN FROM THE 
WEST TOWARD SUNDAY MORNING. TEMPS TO HOLD RELATIVELY MILD THROUGH 
THE OVERNIGHT HOURS...THEN AS ALLUDED TO ABOVE BEGIN TO FALL LATE. 
COULD ALSO SEE A FEW GUSTS IN THE 35-45 MPH RANGE ALONG FAVORED GAP 
WIND LOCNS ALONG WRN GREEN MTN SLOPES DURING THIS PERIOD...BUT A 
QUICK LOOK AT SOUNDING PROFILES SUPPORT A MAINLY STABLE LOWER PBL 
W/THIS EVENT.

THEREAFTER...SFC FRONT PUSHES WELL EAST OF THE AREA DURING SUNDAY AS 
FLOW TURNS WESTERLY UNDER FAIRLY STRONG COLD AIR ADVECTION. TEMPS 
LIKELY TO ONLY RISE A TAD FROM PRIOR NIGHTS MINS WITH HIGHS LIKELY 
OCCURRING DURING THE MORNING HOURS. SOME LAKE AND/OR OROGRAPHICALLY 
ENHANCED SHSN HERE AND ONWARD INTO MONDAY BUT DEEPER MOISTURE REALLY 
ABSENT THUS LOOKING AT ONLY MINOR ACCUM...WITH LITTLE IF ANYTHING IN 
BROADER VALLEY LOCALES. TEMPS TREND BACK TO NEAR OR SLIGHTLY BELOW 
SEASONAL NORMS. BY MONDAY NIGHT RESIDUAL MOISTURE AND SECONDARY SFC 
TROUGH ASSOC W/OLD PARENT OCCLUDED SYSTEM PUSHES INTO THE REGION 
WITH LINGERING THREAT OF SHSN ACROSS THE NORTH. BEHIND THIS BNDRY 
CODLER AIR LIKELY ON TAP BY NEXT TUESDAY THOUGH WITH A TREND TOWARD 
FAIR/DRY CONDS.

&&

.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
THROUGH 18Z WEDNESDAY...VFR/SKC CONDS EXPECTED THROUGH 00Z ACROSS 
MOST OF THE REGION AS HIGH PRESSURE ACROSS GREAT LAKES NOSES 
EASTWARD. EXCEPTION WILL BE ACROSS FAR NERN VT WHERE BKN/OVC VFR TO 
OCCNL MVFR CIGS IN LIGHT SNOWS WILL PERSIST.  WINDS LIGHT TO 
MODERATE 8-12 KTS FROM THE WEST/NORTHWEST ALONG WITH A FEW GUSTS TO 
20 KTS OR SO AT THE KMPV TERMINAL THROUGH SUNSET. BY 
TONIGHT...CONDS WILL TEND TO DETERIORATE ACROSS CENTRAL/NORTHERN 
TERMINALS (ESP KBTV/KSLK/KMSS) AS WRAP-AROUND MARITIME MOISTURE 
SINKS SOUTHWESTWARD INTO THE REGION. WILL ADVERTISE CIGS GRADUALLY 
LOWERING TO MVFR ALONG WITH DEVELOPING LIGHT SNOWS IN THE 03Z-08Z 
TIME FRAME ACCORDINGLY. WINDS WEST TO NORTHWEST 5-10 KTS. 
THEREAFTER...LIGHT SNOWS PERSIST ACROSS THE REGION WITH MVFR TO 
OCCNL IFR CIGS/VSBYS POSSBL. 

OUTLOOK...18Z WEDNESDAY THROUGH SUNDAY...

18Z WED THRU 12Z THUR...MVFR W/OCCNL IFR IN LIGHT SNOWS. BEST 
CONDS WITH SOME VFR AT KPBG/KRUT.

12Z THUR THRU 12Z SAT...MAINLY VFR W/HIGH PRESSURE. SOME LIGHT PCPN 
ENCROACHING FROM THE SW LATE IN THE PERIOD.

12Z SAT THRU 00Z SUN...VFR W/OCCNL MVFR/IFR IN SNOW AND/OR MIXED 
PCPN AS OCCLUDED FRONT CROSSES AREA.

00Z SUNDAY THROUGH 00Z MONDAY...MAINLY VFR THOUGH WITH OCCNL MVFR IN 
MTN SHSN...NAMELY AT THE KSLK TERMINAL.

&&

.EQUIPMENT...
THE TEMPERATURE AND DEW POINT SENSORS AT THE AUTOMATED SURFACE
OBSERVING SYSTEM (ASOS) AT SARANAC LAKE NEW YORK (KSLK) HAVE BEEN
MALFUNCTIONING AND HAVE BEEN TEMPORARILY TURNED OFF. AN
ELECTRONICS TECHNICIAN IS SCHEDULED TO VISIT THE SITE LATER TODAY
TO ATTEMPT REPAIRS OF THESE SENSORS.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.

&&

$$
SYNOPSIS...BANACOS
NEAR TERM...BANACOS
SHORT TERM...BANACOS
LONG TERM...JMG
AVIATION...JMG
EQUIPMENT...