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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBTV 200855
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
355 AM EST FRI DEC 20 2013

.SYNOPSIS...
-- Changed Discussion --
AN ACTIVE WEATHER PATTERN IS ANTICIPATED ACROSS THE NORTH COUNTRY
WITH SEVERAL BOUTS OF PRECIPITATION EXPECTED THROUGH THE WEEKEND. A
SHARP COLD FRONT NEAR THE INTERNATIONAL BORDER WILL PRODUCE PERIODS
OF MIXED PRECIPITATION THROUGH TONIGHT. SNOW ACCUMULATIONS OF 2 TO 6
INCHES CAN BE ANTICIPATED FROM NORTHERN NEW YORK INTO NORTHERN
VERMONT WITH A DUSTING TO 2 INCHES ELSEWHERE. MEANWHILE...ANOTHER
MORE SIGNIFICANT STORM WILL IMPACT THE REGION LATE SATURDAY INTO
SUNDAY...WITH ADDITIONAL MIXED PRECIPITATION. A SIGNIFICANT ICE
ACCUMULATION IS POSSIBLE FOR PARTS OF THE SAINT LAWRENCE
VALLEY...NORTHERN CHAMPLAIN VALLEY...AND NORTHEAST KINGDOM OF
VERMONT BY MIDDAY SUNDAY.
-- End Changed Discussion --

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
AS OF 350 AM EST FRIDAY...WINTER WX ADVISORY CONTINUES THRU UNTIL 4
AM SATURDAY ACRS NORTHERN NY AND WL BE EXPANDED EAST INTO NORTHERN
VT FOR 2 TO 6 INCHES OF SNOW...WITH SOME MINOR ICE ACCUMULATION
POSSIBLE.

BIG PICTURE SHOWS DIGGING CLOSED 5H/7H CIRCULATION ACRS SOUTHERN CA
WITH NUMEROUS EMBEDDED 5H VORT EJECTING FROM SW TROF ACRS THE OHIO
VALLEY INTO THE NORTHEAST CONUS. THIS ENERGY ALOFT IS INTERACTING
WITH INCREASED SUB-TROPICAL MOISTURE...FROM JET ACRS NORTHERN MEXICO
TO PRODUCE AREAS OF PRECIP FROM THE CENTRAL PLAINS INTO THE GREAT
LAKES. MEANWHILE...SFC ANALYSIS SHOWS A SHARP COLD FRNT APPROACHING
THE INTERNATIONAL BORDER THIS MORNING WITH TEMPS BELOW 0F NOTED
BEHIND THIS FRNT ACRS CENTRAL CANADA. THIS BOUNDARY WL SLOWLY DRIFT
SOUTH THIS AFTN...WHILE FLW ABOVE 850MB REMAINS FROM THE
SOUTH/SOUTHWEST WINDS. SFC LOW PRES WL TRACK ALONG THIS BOUNDARY
TODAY AND PRODUCE OCCASIONAL MIXED PRECIP...WITH GREATEST CHANCE FOR
ACCUMULATING SNOWFALL OF 3 TO 6 INCHES FROM KMSS TO ELLENBURG DEPOT
TO JAY PEAK AND MUCH LESS FURTHER SOUTH AS BL TEMPS WARM WELL INTO
THE 30S TO NEAR 40F. AS SFC LOW PRES TRACKS EAST OF OUR CWA...LLVL
SHALLOW COLD AIR MASS QUICKLY ADVECTS DOWN THE CPV/SLV WITH A SHARP
FALL IN TEMPS NOTED OFF THE HIGH RESOLUTION MODELS. THIS SHOWS TEMPS
NEAR 40F AT 18Z AT BTV...BUT QUICKLY FALL INTO THE M/U 20S BY THIS
EVENING AS WINDS SHIFT TO THE NORTH AND LLVL COLD AIR DRAINS DOWN
THE CPV AND SLV. THIS WL HELP TO ENHANCED LLVL FGEN
FORCING...COMBINED WITH FAVORABLE POSITION OF 85H JET OF 40 TO 50
KNOTS AND STRONG EMBEDDED 5H VORTS ALOFT WL RESULT IN PERIODS OF
LIGHT TO MODERATE PRECIP ACRS OUR NORTHERN CWA THRU THIS EVENING. WL
MENTION POPS NEAR 100% NEAR THE BORDER...BUT TAPER TO CHC ACRS
RUTLAND/WINDSOR COUNTIES AS FORCING/MOISTURE IS LIMITED TODAY ACRS
THIS REGION. TEMPS WL RANGE FROM THE U20S/L30S SLV TO MID 40S
SOUTHERN VT.
-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
-- Changed Discussion --
AS OF 350 AM EST THURSDAY...A SIGNIFICANT ICE STORM IS LIKELY WITH
WIDESPREAD POWER OUTAGES POSSIBLE ACRS THE SAINT LAWRENCE AND
PARTS OF THE CHAMPLAIN VALLEYS LATE SAT INTO SUNDAY.

WINTER STORM WATCH FOR ENTIRE CWA...EXCEPT RUTLAND/WINDSOR COUNTIES
FOR POSSIBLE SIGNIFICANT ICE ACCUMULATION >0.50"...ESPECIALLY
CHAMPLAIN AND SAINT LAWRENCE VALLEYS. GIVEN CRNT THERMAL PROFILES
HIGHER TRRN ABOVE 1000 FEET MAY SEE VERY LIMITED ICE ACCUMULATION
AND MOSTLY A RAIN EVENT.

VERY COMPLEX AND DIFFICULT FCST PERIOD...WHICH WL PROBABLY CHANGE
SEVERAL MORE TIMES OVER THE NEXT COUPLE OF DAYS. OVERALL...ALL
MODELS HAVE TRENDED SLIGHTLY COLDER WITH THERMAL PROFILES AND HAVE
SHIFTED THE SFC LOW TRACK SLIGHTLY FURTHER SOUTH. STILL ANTICIPATING
A VERY COMPLEX LLVL THERMAL PROFILE ACRS OUR CWA...WHICH WL HAVE
HUGE IMPLICATION ON PRECIP TYPE...ALONG WITH ELEVATION. ITS HARD TO
BELIEVE BUT THE GREATEST CHCS FOR SIGNIFICANT ICE ACCUMULATION WL BE
ACRS THE SAINT LAWRENCE VALLEY...NORTHERN/CENTRAL CPV...AND PARTS OF
THE NORTHEAST KINGDOM...WHILE MOST OF THE HIGHER TRRN ABOVE 1000 FT
WL SEE MAINLY RAIN WITH UPCOMING EVENT. STILL ANTICIPATING A HUGE
TEMP DIFFERENCE ON SUNDAY WITH MET SHOWING RUTLAND WARMING TO 60F
WHILE...KMSS IS ONLY IN THE M20S. THE WARM TEMPS...COMBINED WITH
SNOW MELT AND QPF COULD PRODUCE SOME HYDRO ISSUES...ESPECIALLY ACRS
CENTRAL/SOUTHERN VT BY SUNDAY AFTN.

LARGE SCALE SYNOPTIC PATTERN SHOWS FULL LATITUDE TROF ACRS THE
CENTRAL PLAINS WITH 5H VORT HELPING TO ENERGIZE SFC LOW PRES ACRS
EASTERN TEXAS BY 18Z SATURDAY. THIS SFC LOW WL TRACK NE INTO THE MS
VALLEY BY 12Z SUNDAY...AND INTO THE NE CONUS BY 00Z MONDAY. A SHARP
LLVL THERMAL BOUNDARY WL BE PRESENT...WHICH IS BEING PRODUCE BY VERY
COLD ARCTIC HIGH PRES ACRS CENTRAL CANADA AND A BERMUDA TYPE HIGH
PRES OFF THE EAST COAST...WITH FAST CONFLUENT FLW ALOFT. PLENTY OF
MOISTURE WL BE AVAILABLE WITH PWS >1.0" OR 200 TO 300% OF NORMAL
ACRS OUR CWA...ALONG WITH VERY STRONG LLVL CONVERGENCE FROM BOUNDARY
AND GOOD 925MB TO 850MB FGEN FORCING. ALSO...HELPING TO ENHANCE
MOISTURE ADVECTION WL BE NOSE OF 85H JET OF 50 TO 70 KNOTS ACRS
CENTRAL PA INTO EASTERN NY ON SAT NIGHT INTO SUNDAY...WHILE A RRQ OF
THE POLAR JET IS LOCATED ACRS CENTRAL CANADA. THIS MOISTURE AND
DYNAMICS WL PRODUCE A WIDESPREAD 0.75" TO 1.50" PRECIP EVENT ACRS
OUR REGION...WITH HEAVIEST AMOUNTS FROM THE DACKS INTO
CENTRAL/SOUTHERN VT. ISOLATED AMOUNTS MAY APPROACH 2.0". EXPECT THE
HEAVIER AND STEADIER PRECIP TO TAPER OFF BY MIDDAY SUNDAY AS DRY
SLOT DEVELOPS ACRS OUR CWA. SOUNDINGS SHOW AREAS OF DRIZZLE WITH
POCKETS OF FREEZING DRIZZLE POSSIBLE AFT 18Z SUNDAY.

VERY COMPLICATED LLVL THERMAL PROFILES WITH SFC HIGH PRES LOCATED
ACRS SOUTHERN CANADA HELPING TO ADVECT A VERY SHALLOW LLVL COLD AIR
MASS INTO OUR CWA...WHILE SOUTH TO SOUTHWEST WINDS BTWN 900MB AND
700MB WL PUSH VERY WARM AIR ALOFT. GIVEN THE VERY SHALLOW AIR
MASS...THINKING BEST CHC FOR SIGNIFICANT ICE ACCUMULATION WL BE ACRS
THE VALLEYS BLW 1000 FT...ESPECIALLY THE SLV AND NORTHERN/CENTRAL
CPV. BOTH THE NAM/LOCAL WRF SHOW STRONG LLVL CAA WITH 1000MB TEMPS
BTWN -2C AND -8C ACRS THE CPV/SLV...WHILE ACRS THE HIGHER TRRRN
VALUES ARE BTWN +4 TO +10C...EVEN ACRS EASTERN VT. THIS LLVL COLD
AIR REMAINS LOCKED IN PLACE DURING MOST OF THE EVENT...WITH BUFKIT
SOUNDINGS SHOWING 0.75 TO 1.25" OF QPF FALLING IN THE FORM OF FZRA
AT MSS/BTV/PBG...WHILE MAINLY PLAIN RAIN IS THE PRECIP TYPE AT
MPV/SLK/RUT/VSF. THIS WL RESULT IN SIGNIFICANT ICE ACCUMULATION IN
THE VALLEY...WITH DIFFICULT DRIVING AND POWER OUTAGES LIKELY. WL
ISSUE WATCH FOR ALMOST ENTIRE AREA EXCEPT RUTLAND/WINDSOR
COUNTIES...GIVEN STILL SOME UNCERTAINTY ON STORM TRACK AND THERMAL
PROFILES...AS A SLIGHTLY FURTHER SOUTH TRACK WOULD RESULT IN DEEPER
COLDER AIR AND MORE ICE FOR EVEN THE HIGHER TRRN. THINKING
EVENTUALLY AN ICE STORM WARNING WL BE NEEDED FOR THE CPV/SLV AND
PARTS OF THE NEK...WITH ADVISORY TYPE EVENT FOR MTNS OF NY INTO
CENTRAL VT FROM SAT INTO SUNDAY.

FOR TEMPS TONIGHT EXPECT A LARGE RANGE BTWN LOWS IN THE L20S
SLV/NORTHERN CPV TO M/U 30S ACRS SOUTHERN RUTLAND/WINDSOR COUNTIES.
ON SATURDAY...TEMPS WL WARM INTO THE 40S SOUTHERN ZNS TO M/U 30S
MTNS AND ONLY IN THE 20S SLV AND PARTS OF THE NORTHERN CPV. TEMPS ON
SUNDAY WL RANGE FROM THE COOLER 20S TO NEAR 30 AROUND KMSS TO NEAR
L/M 50S ACRS SOUTHERN RUTLAND/WINDSOR COUNTIES...WITH VALUES IN THE
U30S TO LOWER 40S IN THE MTNS. THE COLDEST READINGS WL BE ACRS THE
CPV AND SLV AREAS AND PARTS OF THE NEK.
-- End Changed Discussion --

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
-- Changed Discussion --
AS OF 350 AM EST THURSDAY...PRECIPITATION WILL FINALLY TAPER OFF
SUNDAY NIGHT AS THE WARM FRONT AND SURFACE LOW EVENTUALLY MOVE
EAST OF THE AREA. THERMAL PROFILE SHOULD ALSO BEGIN TO TREND
TOWARD MAINLY A MIX OF RAIN AND SNOW FOR SUNDAY NIGHT AND
EVENTUALLY TO JUST SNOW SHOWERS AS COLD AIR ADVECTION DEVELOPS
OVER THE AREA. THE COLD AIR ADVECTION WILL CONTINUE INTO TUESDAY
AND WEDNESDAY...AND WITH HIGH PRESSURE BUILDING IN...COLDER AND
DRIER WEATHER IS EXPECTED FOR CHRISTMAS EVE AND CHRISTMAS DAY. A
RETURN TOWARD SEASONAL TEMPERATURES IS EXPECTED ON THURSDAY ALONG
WITH THE CHANCE FOR SOME SNOW SHOWERS AS AN UPPER LEVEL TROUGH OF
LOW PRESSURE MOVES INTO THE REGION.
-- End Changed Discussion --

&&

.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
THROUGH 06Z SATURDAY...MVFR CEILINGS WILL EXIST THROUGH THE ENTIRE
PERIOD. LIGHT PRECIPITATION WILL SPREAD ACROSS THE AREA FROM WEST
TO EAST...ESPECIALLY OVER NORTHERN NEW YORK AND THE NORTHERN HALF
OF VERMONT...BEGINNING FROM 08Z TO 12Z...AND CONTINUING THROUGH
MUCH OF THE PERIOD. THE PRECIPITATION WILL BE EITHER LIGHT SNOW OR
LIGHT RAIN...WITH SOME LIGHT SLEET MIXED IN AFTER 20Z.
VISIBILITIES WILL GENERALLY BE IN THE MVFR/VFR CATEGORIES WITH
PERIODS OF IFR CONDITIONS AT KMSS AND KSLK AFTER 14Z.

OUTLOOK 06Z SATURDAY THROUGH TUESDAY...

06Z SATURDAY THRU 18Z SATURDAY...MVFR/IFR WITH PERIODS OF LIGHT
SNOW AND/OR LIGHT MIXED PCPN.

18Z SATURDAY THRU 00Z MONDAY...IFR/MVFR IN WIDESPREAD MODERATE TO
POSSIBLY HEAVY WINTRY MIXED PRECIPITATION.

00Z MONDAY ONWARD...VFR/MVFR WITH SCATTERED SHSN/FLURRIES...ESP AT
KSLK/KMPV.

&&

.HYDROLOGY...
-- Changed Discussion --
STORM TOTAL PRECIPITATION WILL RANGE BTWN 0.75 AND 1.50" WITH
LOCALIZED HEAVIER AMOUNTS CLOSE TO 2" POSSIBLE BY SUNDAY AFTN. THE
HEAVIER AND STEADIER PRECIP SHOULD TAPER OFF BY MIDDAY SUNDAY...AS A
WELL DEFINED DRY SLOT DEVELOPS ACRS THE REGION. MOST OF THE QPF WL
FALL IN THE FROZEN PHASE ACRS OUR NORTHERN CWA...BUT RAIN IS
EXPECTED OVER CENTRAL AND SOUTHERN VT...ESPECIALLY IN THE HIGHER
TRRN. THIS COMBINED WITH MELTING SNOW PACK AND ASSOCIATED RUNOFF WL
CAUSE SIGNIFICANT RISES ON STREAMS AND RIVERS. THE OTTER CREEK...MAD
RIVER...AND AUSABLE RIVER WL HAVE TO BE WATCHED CLOSELY. IN
ADDITION...SOME MINOR ICE JAM FLOODING WL BE POSSIBLE IN SMALLER
STREAM BASINS. A FLOOD WATCH MAYBE NEEDED LATER TODAY...FOR THE
POTENTIAL OF MINOR FLOODING.
-- End Changed Discussion --

&&

.EQUIPMENT...
AS OF 647 PM EST THURSDAY...KTYX RADAR IS DOWN UNTIL FURTHER
NOTICE DUE TO MOTOR FAILURES. TECHS HAVE ORDERED PARTS BUT NO
ESTIMATION AS TO WHEN KTYX WILL BE BACK IN SERVICE IS KNOWN AT
THIS TIME.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
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VT...WINTER WEATHER ADVISORY UNTIL 4 AM EST SATURDAY FOR VTZ001>003-
     016.
     WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SUNDAY
     EVENING FOR VTZ001>010-016>018.
NY...WINTER WEATHER ADVISORY UNTIL 4 AM EST SATURDAY FOR NYZ026>031-
     087.
     WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SUNDAY
     EVENING FOR NYZ026>031-034-035-087.
-- End Changed Discussion --

&&

$$
SYNOPSIS...TABER
NEAR TERM...TABER
SHORT TERM...TABER
LONG TERM...EVENSON
AVIATION...EVENSON/JMG
HYDROLOGY...
EQUIPMENT...WFO BTV