Area Forecast Discussion
Issued by NWS Burlington, VT

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000
FXUS61 KBTV 300239
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
939 PM EST THU JAN 29 2015

.SYNOPSIS...
A WEAK CLIPPER LIKE SYSTEM WILL PRODUCE A WIDESPREAD LIGHT SNOW
TONIGHT INTO FRIDAY...FOLLOWED BY UPSLOPE SNOW SHOWERS AND
BITTERLY COLD TEMPERATURES FRIDAY NIGHT. HIGH PRESSURE WILL BUILD
IN FOR THE WEEKEND WITH TEMPERATURES MUCH BELOW NORMAL.
TEMPERATURES OF 10 TO 15 DEGREES BELOW NORMAL WILL PERSIST INTO
THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 7 AM FRIDAY MORNING/...
AS OF 932 PM EST THURSDAY...
HEADLINES: WINTER WEATHER ADVISORIES CONTINUE TO BE IN AFFECT FOR
ENTIRE FORECAST AREA FOR TONIGHT INTO FRIDAY EVENING.

NO SIGNIFICANT CHANGES TO THE FORECAST. OBSERVATIONS OVER THE
SAINT LAWRENCE VALLEY INDICAT LIGHT SNOW IS BEGINNING TO FALL SO
THE BOUNDARY LAYER RH HAS FINALLY SATURATED OVER NORTHERN NEW
YORK. THOSE SHOWERS WILL CONTINUE TO DEVELOP AND BRING LIGHT TO
MODERATE SNOW OVER THE AREA GRADUALLY MOVING EAST. THE FORECAST IS
IN GOOD SHAPE TO HAVE SNOW REACH THE CHAMPLAIN VALLEY IN 05-07Z
TIME FRAME WITH 1 TO 1.5 INCHES TO FALL OVERNIGHT BEFORE SUNRISE.
TEMPS ARE ON TRACK TO DROP INTO THE LOW 20`S TO MID TEENS
OVERNIGHT UNDER OVERCAST SKIES.

PREVIOUS DISCUSSION...WV/IR SATELLITE SHOW THE CLIPPER DEVELOPING
QUITE NICELY OVER THE GREAT LAKES AND BEGINNING TO WRAP UP. THE
MID TO UPPER LEVEL MOISTURE IS QUICKLY INCREASING HOWEVER THAT
HASN`T YET REACHED THE GROUND OVER NORTHERN NEW YORK. CURRENT
COMPOSITE RADAR AND GROUND TRUTH PRESENT TWO DRASTICALLY DIFFERENT
SOLUTIONS RIGHT NOW AS THE SURFACE OBS ARE SHOWING DEWPOINT
DEPRESSIONS OF 21 DEGREES AT OGDENSBURG. AT THAT POINT THE LOW
LEVEL MOISTURE JUST HASN`T REACHED THE GROUND AND THE METAR IS
REPORTED CLEAR BELOW 12,000 FEET. UNTIL THE LOW LEVELS BECOME
SATURATED EXPECT THE PRECIP TO ESSENTIALLY BE VIRGA. ADDITIONALLY
ACROSS MUCH OF THE ST LAWRENCE VALLEY SURFACE TEMPS ARE IN THE MID
TO UPPER 30`S SO ANY PRECIP THAT IS FALLING WILL MOST LIKELY BE A
WINTRY MIX OF SNOW OR RAIN FOR THE NEXT HOUR OR TWO. EXPECT OVER
THE NEXT 2-3 HOURS THE LOW LEVELS SHOULD SATURATE AND BECOME SNOW
SHOWERS FOR MOST OF THE OVERNIGHT HOURS AS THE CLIPPER MOVES
EASTWARD. ONLY REAL CHANGES TO THE FORECAST WERE TO UP THE TEMPS
OVER THE ST LAWRENCE VALLEY MATCHING OBS AND THEN TREND BACK HOW
QUICKLY THE PRECIP MOVES ACROSS THE FORECAST REGION DUE TO THE DRY
AIR IN THE VERY LOW LEVELS. THE REST OF THE FORECAST LOOKS ON
TRACK TO DROP INTO THE UPPER TEENS TO NEAR 20 ACROSS THE REGION
WITH LIGHT TO MODERATE SNOWFALL OVERNIGHT.


&&

.SHORT TERM /7 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
AS OF 330 PM EST THURSDAY...THE CENTER OF THE CLIPPER TRAVERSES
NEAR THE INTERNATIONAL BORDER EARLY FRIDAY MORNING...THEN
REDEVELOPS OFF THE SOUTHERN NEW ENGLAND COAST IN THE AFTERNOON AS
THE ASSOCIATED MID LEVEL TROUGH DIGS AND TAKES ON A NEGATIVE TILT.
THIS WILL RESULT IN THE SURFACE LOW SLOWING ITS EASTWARD
PROGRESSION INTO GULF OF MAINE. THE RESULT WILL BE A TRANSITION OF
SYNOPTIC SNOW TO UPSLOPE SNOW OR SNOW SHOWERS ACROSS
VERMONT...WHICH WILL CONTINUE INTO FRIDAY NIGHT. THE SNOW WILL
TAPER OFF EARLIER ACROSS NORTHERN NEW YORK.

BEHIND THE SURFACE LOW AND WITH PASSAGE OF COLD FRONT...SOUTHERLY
WINDS WILL SHIFT INTO THE NORTH. THIS COMBINED WITH LINGERING
MOISTURE WILL PRODUCE UPSLOPE SNOW SHOWERS WITH FROUDE NUMBERS
SHOWING BLOCKED FLOW. WHEN ALL IS SAID AND DONE...EXPECT 3-7 INCHES
OF SNOWFALL FOR THE ST LAWRENCE VALLEY...STRETCHING ACROSS THE
NORTHERN TIER OF OUR ZONES ACROSS THE CENTRAL CHAMPLAIN VALLEY AND
ALL OF NORTHERN VERMONT. DUE TO SHADOWING...ESSEX COUNTY NY AND
THE SOUTHERN CHAMPLAIN VALLEY AND SOUTH CENTRAL VT WILL RECEIVE
JUST A BIT LESS...WITH 2-5 INCHES EXPECTED. SOME LOCALLY HIGHER
AMOUNTS ARE ALSO POSSIBLE...ESPECIALLY OVER THE WESTERN SLOPES OF
THE NORTHERN GREEN MOUNTAINS.

THE NORTHWEST FLOW WILL USHER IN COLDER AIR WITH NON DIURNAL
TEMPERATURE TREND EXPECTED FRIDAY. DRIER AIR WILL ALSO BE
FILTERING IN FRIDAY ALLOWING SKIES TO CLEAR ACROSS NORTHERN NEW
YORK. PRESSURE GRADIENT WILL INCREASE LATE FRIDAY INTO FRIDAY
NIGHT WITH COASTAL LOW DEEPENING AND HIGH PRESSURE BUILDING TO
OUR WEST. THESE FEATURES WILL RESULT IN VERY COLD TEMPERATURES
FRIDAY NIGHT INTO SATURDAY. 925MB TEMPS WILL FALL TO BETWEEN -10C
AND -20C FRIDAY NIGHT...WHICH WILL BE REFLECTED AT THE SURFACE IN
TERMS OF SATURDAY MORNING LOWS RANGING FROM A BIT ABOVE ZERO
SOUTHERN AND EASTERN VERMONT TO THE TEENS BELOW ZERO ACROSS
MUCH OF NORTHERN NEW YORK. COMBINATION OF TEMPS AND WIND WILL
LIKELY RESULT IN SOME WIND CHILL ISSUES...WITH POSSIBILITY OF AT
LEAST ADVISORIES FOR LATE FRIDAY NIGHT INTO SATURDAY.

MAX TEMPS SATURDAY UNDER PARTLY TO MOSTLY SUNNY SKIES WILL BE
ONLY IN THE SINGLE NUMBERS TO LOWER TEENS...ALTHOUGH WINDS WILL
ABATE DURING THE AFTERNOON. ANOTHER FRONT WILL DROP INTO THE AREA
FROM THE NORTHWEST SATURDAY NIGHT. NOT MUCH IN WAY OF AVAILABLE
MOISTURE...BUT ENOUGH FOR AT LEAST THE MENTION OF A CHANCE OF SNOW
SHOWERS...ESPECIALLY OVER THE NORTHERN MOUNTAINS.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 254 PM EST THURSDAY...VERY LITTLE CHANGE TO PREVIOUS
FORECAST THINKING FOR THE EXTENDED PERIOD AS TODAYS 12Z MODEL
SUITE REMAINS IN GOOD AGREEMENT KEEPING ANY MAJOR SYSTEMS AWAY
FROM THE NORTH COUNTRY.

LINGERING SNOW SHOWERS REMAIN POSSIBLE MAINLY ACROSS THE HIGHER
TERRAIN SUNDAY AS AN ARCTIC FRONT PUSHES INTO THE REGION. TRICKY MAX
TEMPS FORECAST AT THIS TIME BASED ON FRONTAL PASSAGE TIMING, BUT
BASED ON FALLING 925-850MB TEMPS THROUGH THE DAY THINK HIGHS WILL BE
EARLY IN THE MORNING AND SLOWLY FALL OFF THROUGH THE DAY. MEANWHILE,
STILL MONITORING THE POTENTIAL DEVELOPMENT OF SURFACE LOW PRESSURE
OVER THE TENNESSEE RIVER VALLEY LATE SUNDAY INTO SUNDAY NIGHT WHICH
WILL INTENSIFY OFF THE EASTERN SEABOARD MONDAY. LATEST TRENDS OF THE
12Z ECMWF AND GFS CONTINUE THE IDEA THAT THIS SOUTH STREAM ENERGY
DOESN`T PHASE WITH THE NORTHERN STREAM TROUGH DIGGING THROUGH THE
GREAT LAKES WHICH NEVER BECOMES NEGATIVELY TILTED AND REMAINS AN
OPEN WAVE AT 500MB. THIS RESULTS IN A MORE WESTERLY TRACK OF THE
SURFACE LOW INITIALLY, CAUSING IT TO PASS WELL TO OUR SOUTH AND EAST
OF THE BENCHMARK. SO BASICALLY A NON-EVENT FOR US, SIGH.

BEYOND MONDAY PATTERN TURNS COLD AND DRY FOR MONDAY NIGHT THROUGH
TUESDAY NIGHT AS A STRONG 1030MB HIGH SETTLES OVER THE MID-ATLANTIC
AND NORTHEAST. TEMPS WILL STRUGGLE TO WARM INTO THE SINGLE DIGITS
TUESDAY AND FALL BELOW ZERO AREA-WIDE BOTH NIGHTS. THIS WILL BE A
BRIEF BLAST OF CLOD THOUGH AS THE HIGH SHIFTS EAST OFF THE COAST FOR
WEDNESDAY WITH SOUTHERLY RETURN FLOW WARMING TEMPS BACK INTO THE
TEENS AND 20S. NEXT CHANCE FOR SNOW COMES WITH A CLIPPER SYSTEM
SHIFTING THROUGH THE AREA WEDNESDAY AND WEDNESDAY NIGHT.

&&

.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
THROUGH 00Z SATURDAY...PERIODS OF LIGHT SNOW WILL AFFECT TAF SITES
THROUGH FRIDAY BRINGING A VARIETY OF FLIGHT CATEGORIES...BUT
A PREDOMINANT TREND TO MVFR/IFR. LIGHT SNOW SHOWERS WILL
OVERSPREAD THE REGION BETWEEN 00Z AND 04Z...WITH GREATEST COVERAGE
AND INTENSITY GENERALLY 06Z TO 12Z. THUS WILL SEE A DOWN TREND IN
VISIBILITIES AND CEILINGS TO MAINLY MVFR/IFR. GUSTY SOUTH WINDS
UP TO 25 KNOTS WILL GRADUALLY DECREASE TOWARDS MORNING. WINDS WILL
TURN TO THE NORTHWEST FROM 5 TO 15 KNOTS WITH SOME HIGHER GUSTS ON
FRIDAY...LEADING TO MORE TERRAIN DRIVEN SNOW SHOWERS CONTINUING
THROUGH THE DAY...ESPECIALLY BTV/MPV/RUT/SLK.

OUTLOOK 00Z SATURDAY THROUGH TUESDAY...

00Z SATURDAY-12Z SATURDAY...SLOW IMPROVEMENT AS SNOW SHOWERS END.
GUSTY NORTHWEST WINDS WILL RESULT IN AREAS OF BLOWING SNOW.

12Z SATURDAY-12Z MONDAY...VFR.

12Z MONDAY-00Z WEDNESDAY...MAINLY VFR AS SYSTEM SLIDES SOUTH OF
REGION.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...WINTER WEATHER ADVISORY UNTIL 1 AM EST SATURDAY FOR VTZ001>012-
     016>019.
NY...WINTER WEATHER ADVISORY UNTIL 7 PM EST FRIDAY FOR NYZ026>031-
     034-035-087.

&&

$$
SYNOPSIS...RJS
NEAR TERM...DEAL
SHORT TERM...RJS
LONG TERM...LAHIFF
AVIATION...MUCCILLI/NASH


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