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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBTV 252014
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
414 PM EDT SAT MAY 25 2013

.SYNOPSIS...
A DEEP TROUGH AND ASSOCIATED COASTAL LOW PRESSURE SYSTEM WILL
PRODUCE A WIDESPREAD 1 TO 2 INCHES OF ADDITIONAL RAINFALL ACROSS THE
NORTH COUNTRY THIS WEEKEND. FURTHERMORE...SOME ACCUMULATING SNOWFALL
WILL BE POSSIBLE ACROSS THE HIGHER SUMMITS OF THE ADIRONDACK AND
GREEN MOUNTAINS. THIS RAINFALL WILL CAUSE SIGNIFICANT RISES ON
LOCAL WATERWAYS...WITH SOME RIVER FLOODING POSSIBLE. TEMPERATURES
WILL BE MUCH BELOW NORMAL THROUGH SUNDAY...WITH A WARMING TREND
EXPECTED BY EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH SUNDAY/...
AS OF 122 PM EDT SATURDAY...HAVE HAD SOME REPORTS OF SNOW AS LOW
AS 1500 FEET THIS MORNING. FORECAST STILL ON TRACK WITH LOW IN THE
GULF OF MAINE AND PRECIP SHIELD ACROSS VT AND EASTERN NY. PREVIOUS
DISCUSSIONS FOLLOW.

NO SIGNIFICANT CHANGES TO PREVIOUS
FORECAST. DID ADD IN SOME WORDING FOR STRONG GUSTS OUT OF THE
NORTH TODAY...ESPECIALLY IN THE CHAMPLAIN VALLEY. PREVIOUS
FORECASTERS THOUGHTS STILL VERY MUCH IN LINE WITH
RADAR...SATELLITE AND CURRENT OBS. PREVIOUS DISCUSSION FOLLOWS.

VERY MINOR UPDATE TO FINE TUNE POPS/TEMPS AND WINDS BASED ON CRNT
OBS. RADAR CONTS TO SHOW BANDS OF LIGHT TO MODERATE RAIN ROTATING
ACRS OUR CWA...WITH SOME BRIGHT BAND SIGNATURES ASSOCIATED WITH
THE MELTING LAYER ON KCXX RADAR. WATER VAPOR SHOWS A CLASSIC
BACKSIDE DEFORMATION ZN DEVELOPING ACRS CENTRAL VT INTO NORTHERN
NY ATTM. THIS WL PRODUCE PERIODS OF RAIN...WITH SOME HEAVY AT
TIMES THRU TODAY. QPF AMOUNTS LOOK GOOD. JUST STARTING TO SEE
RISES ON LOCAL WATERWAYS AND EXPECT RIVER FLOODING TO BECOME MORE
OF AN ISSUE BY THIS AFTN. FLOOD WATCH LOOKS VERY GOOD.
OTHERWISE...TEMPS WL HOLD IN THE M/U 30S MTNS TO L/M40S VALLEYS
WITH SOME L/M50S POSSIBLE IN THE SLV TODAY. HAVE DISCARDED THE LAV
GUIDANCE WHICH SHOWS BTV DROPPING INTO THE MID 30S BY NOON
TODAY...ITS LATE MAY AND THIS SEEMS HIGHLY UNLIKELY.

AS FOR THE SNOW...PICO WEB CAM SHOWS THE SUMMIT IS WHITE...WITH
SOME MIXING OF SNOW AND RAIN DOWN TO THE KILLINGTON BASE AREA.
CRNT ACCUMULATING SNOW LEVELS ARE AROUND 3500FT...EXPECT THEM TO
DROP BTWN 2000 AND 2500 FT BY THIS EVENING...WITH SOME
ACCUMULATION POSSIBLE. MEANWHILE...ACCUMULATING SNOW WILL CONT
ACRS THE EASTERN DACKS ABOVE 3500 FT...AS WHITEFACE SUMMIT TEMP IS
DOWN TO 27F.

OVERALL FCST REMAINS ON TRACK WITH EXPECTED QPF AMOUNTS AND
IMPACTS ACRS OUR CWA. STILL ANTICIPATING STORM TOTAL PRECIP OF 1
TO 2 INCHES WITH LOCALIZED 3 INCH AMOUNTS ACRS THE WESTERN
SLOPES...PARTS OF THE CPV...AND MTNS OF NORTH-CENTRAL VT BY SUNDAY
AFTN. IN ADDITION...STILL EXPECTING SOME ACCUMULATING HEAVY WET
SNOW ABOVE 2000 FEET...ESPECIALLY SAT NIGHT INTO SUNDAY MORNING
ACRS THE NORTHERN DACKS AND GREEN MTNS.

FCST CHALLENGE IS IMPACTS OF HEAVY RAINFALL ON AREA
WATERWAYS...FOLLOWED BY POTENTIAL IMPACTS OF SNOW ACRS HIGHER TRRN.

WATER VAPOR SHOWS AN IMPRESSIVE NEGATIVELY TILTED 7/5H CIRCULATION
ACRS THE MID ATLANTIC STATES WITH A BAROCLINIC LEAF STRUCTURE ACRS
OUR FA ASSOCIATED WITH RRQ OF 25H JET OVER EASTERN CANADA. THIS
CLOSED SYSTEM WL ADVECT PLENTY OF DEEP ATLANTIC MOISTURE INTO OUR
CWA THRU TONIGHT...WITH FAVORABLE BACKSIDE DEFORMATION DEVELOPING BY
THIS EVENING. OVERALL...MODELS IN VERY GOOD AGREEMENT WITH SYSTEM
BECMG VERTICALLY STACKED OVER THE GULF OF MAINE...AND THE ASSOCIATED
QPF ACRS OUR CWA. GFS/NAM AND ECMWF ALL SHOW IMPRESSIVE 7H FGEN
FORCING...STRONG 850 TO 500MB Q-VECTOR CONVERGENCE...AND DEEP 850
TO 500MB UVVS ACRS OUR CWA THRU 06Z SUNDAY. THIS WL RESULT IN
PERIODS OF RAIN...WHICH WL BE MODERATE TO HEAVY AT
TIMES...ESPECIALLY THRU THIS EVENING. BY LATE TONIGHT INTO
SUNDAY...SYSTEM WL TRANSITION FROM LARGE SCALE SYNOPTIC LIFT TO
MESOSCALE FEATURES DRIVE BY THE TRRN. GFS/NAM SHOWS VERY FAVORABLE
850 TO 700MB RH AND LLVL WINDS LATE TONIGHT INTO SUNDAY FOR ENHANCED
PRECIP ACRS THE CPV...WESTERN SLOPES...AND NORTH/CENTRAL MTNS OF VT.
THIS FAVORABLE MOISTURE/LIFT IS PRESENT THRU 18Z SUNDAY...BEFORE
FINALLY WEAKENING BY EVENING. WL CONT TO MENTION POPS NEAR 100% FOR
TODAY AND TONIGHT...BUT LIKELY/CAT POPS ON SUNDAY...ESPECIALLY IN
THE MORNING. GIVEN...THE DEEP CLOSED CIRCULATION FEEL PRECIP/CLOUDS
WL LINGER THRU MIDDAY SUNDAY...BUT WL TAPER OFF BY AFTN. ALSO...FEEL
QPF/POPS WL BE MUCH LESS ACRS THE SLV...AS MODELS SHOW LIMITED
LIFT/RH. THINKING MOSTLY LOW LIKELY WESTERN DACKS TO CHC POPS SLV.
THIS AREA WL ALSO SEE THE WARMEST TEMPS ON SAT AND SUNDAY...HIGHS IN
THE 50S.

STILL ANTICIPATING STORM TOTAL QPF AMOUNTS BTWN 1 AND 2 INCHES WITH
LOCALIZED 3 INCHES POSSIBLE...ACRS THE CPV...WESTERN SLOPES...AND
MTNS OF NORTHERN VT. THINKING CPV CONVERGENCE AND UPSLOPE FLW WL
HELP TO ENHANCE QPF AMOUNTS ACRS THE WESTERN SLOPES AND CPV. MUCH
LESS QPF IS ANTICIPATED ACRS THE SLV/WESTERN DACKS...GENERALLY
<0.25". ALSO...THINKING AMOUNTS ACRS THE CT RIVER VALLEY WL BE
CLOSER TO 1.0". THIS WL CAUSE SIGNIFICANT RISES ON LOCAL
WATERWAYS...WITH SOME MAIN STEM FLOODING POSSIBLE. SEE HDYRO SECTION
BLW FOR MORE INFO.

NOW FOR THE HARDEST PART OF THE FCST...TRYING TO DETERMINE SNOW
LEVELS AND POTENTIAL IMPACTS. NAM/GFS AND LOCAL WRF BUFKIT SOUNDINGS
SHOW THERMAL PROFILES BECMG COLD ENOUGH BY 00Z THIS EVENING FOR SNOW
ABOVE 2000 FT. STILL HAVING A HARD TIME DETERMINING WHERE THE COLD
AIR IS COMING FROM...AS OUR LLVL CAA IS LIMITED. THINKING DYNAMIC
COOLING AND HEAVIER PRECIP WL MIX COLDER AIR ALOFT TWD THE
SFC...AS COLD CORE LOW MOVES CLOSER. THIS IS EXTREMELY TRICKY TO
DETERMINE...ESPECIALLY IN LATE MAY...WITH A VERY HIGH SUN ANGLE.
HAVE NOTED 28F AT WHITEFACE AND 32 ATOP MOUNT MANSFIELD....WITH
WHITEFACE WEB CAM ALREADY SHOWING THE GROUND WHITE...BEFORE SUNSET
ON FRIDAY EVENING. BOTH GFS/NAM SHOW A RIBBON OF 85H TEMPS BTWN
-1C AND -3C...AND 925MB TEMPS NEAR 0C DEVELOPING ACRS OUR CWA
TODAY. THINKING SNOW LEVELS WL START NEAR SUMMIT LEVEL (3500 TO
4000 FEET) TODAY...BUT DROP TO NEAR 2000 FT BY THIS EVENING.
EXPECT A SHARP INCREASE IN ACCUMULATING SNOWFALL ACRS THE MTNS AS
YOU INCREASE YOUR ELEVATION ABOVE 2500 FT. THINKING BTWN 1 AND 3 INCHES
WL BE POSSIBLE BY SUNDAY MORNING BTWN 2000 AND 2500 FEET...WITH
OVER 6 INCHES LIKELY AT THE SUMMITS FROM MT MANSFIELD TO JAY PEAK. I
REALIZE WE TECHNICALLY DON`T FCST FOR THE SUMMITS...BUT GIVEN THE
HOLIDAY WKND AND POTENTIAL FOR HIKERS/CAMPERS IN THE MTNS AND
POSSIBLE ISOLATED POWER OUTAGES WL ISSUE SPS TO HIGHLIGHT THIS
POTENTIAL. ON A SIDE NOTE...IF WE CAN CLR SKIES LATE SUNDAY
AFTN...THE SNOW COVERED MTN SUMMITS SHOULD MAKE FOR SOME GREAT
PICTURES.

THE COMBINATION OF PRECIP/CLOUDS AND PROGGED 85H TEMPS NEAR 0C...WL
SUPPORT HIGHS ONLY IN THE M/U30S MTNS TO L/M 40S CPV/CT RIVER
VALLEY. WARMEST TEMPS WL BE ACRS THE SLV...READINGS WL WARM INTO THE
50S. TEMPS WL ONLY FALL SLIGHTLY TONIGHT...AS WINDS/PRECIP AND
CLOUDS PREVAIL...THINKING L/M 30S MTNS TO U30S TO L40S. ON
SUNDAY...TEMPS WL BECM TRICKY...ESPECIALLY IF WE BREAK OUT INTO SOME
SUN LATE IN THE AFTN. EXPECT LATE DAY HIGHS FOR THE CPV...WITH
VALUES REACHING THE L/M 50S...WITH MAINLY 40S IN THE MTNS AND L60S
IN THE SLV. MOST OF THE MARATHON WL EXPERIENCE LIGHT RAIN WITH COOL
TEMPS AND BREEZY NORTH WINDS...ESPECIALLY NEAR THE LAKE ON SUNDAY
MORNING. CONDITIONS WL IMPROVE BY SUNDAY AFTN WITH SCATTERED SHOWERS
AND TEMPS SLOWLY WARMING TO NEAR 50F...AND LIGHTER WINDS.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY/...
AS OF 440 AM EDT SATURDAY...MID/UPPER LVL TROF WL SLOWLY LIFT NE INTO
THE CANADIAN MARITIMES AS SFC HIGH PRES BUILDS INTO OUR CWA. THIS
WL RESULT IN A SLOW CLEARING TREND WITH TEMPS RETURNING TO NEAR
NORMAL LVLS BY MONDAY. LATEST GUIDANCE SUGGESTS THE POTENTIAL FOR
SOME FROST ACRS THE SHELTERED VALLEYS OF THE DACKS AND PARTS OF
VT. THIS MAYBE DIFFICULT GIVEN THE VERY SATURATED LLVLS AND
POTENTIAL FOR FOG DEVELOPMENT IF SKIES CLR AND WINDS DECREASE.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
AS OF 440 AM EDT SATURDAY...PATTERN CHANGE TAKES PLACE IN THE EXTENDED
AS DRIER NORTHWEST FLOW ALOFT EXISTS MONDAY NIGHT THROUGH TUESDAY
NIGHT. WE WILL START TO SEE A GRADUAL WARMING TREND TAKE PLACE
DURING THIS TIME PERIOD. MORE PRONOUNCED WARMING WILL TAKE PLACE
DURING THE MIDDLE AND LATTER PART OF THE WEEK WHEN A WARM FRONT
LIFTS NORTH OF THE AREA AND WE GET INTO THE WARM SECTOR WITH
BUILDING UPPER RIDGE MOVING IN. FIRST THE WARM FRONT WILL PROVIDE
A FOCUS WEDNESDAY FOR CONVECTION AS SUFFICIENT INSTABILITY MOVES
INTO THE REGION. THUS HAVE KEPT A CHANCE OF THUNDERSTORMS IN THE
FORECAST FOR WEDNESDAY WITH SOME LINGERING THREAT ON THURSDAY AS
FRONT GRADUALLY LIFTS NORTH OF THE BORDER. ONCE IT
DOES...SOUTHWEST FLOW ALOFT DEVELOPS AND BRINGS IN NOTICEABLY
WARMER LOW LEVEL TEMPERATURES AND THIS SUGGESTS HIGHS CLIMBING
INTO THE UPPER 70S TO MID 80S THURSDAY AND FRIDAY. LACK OF FORCING
SUGGESTS CONVECTIVE THREAT IS MINIMAL AND HAVE THUS KEPT THE
FORECAST DRY ON FRIDAY.

&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
-- Changed Discussion --
THROUGH 18Z SUNDAY...MAINLY IFR/MVFR CEILINGS IN LIGHT RAIN THROUGH
THE PERIOD AS A LOW PRESSURE AREA REMAINS OFF THE NEW ENGLAND
COAST THROUGH THE PERIOD. NORTHERLY SURFACE WIND GUSTS AT OR ABOVE
20 KNOTS THROUGH THE PERIOD. COLDER AIR ALOFT WILL PRODUCE LIGHT SNOW
OVER THE HIGHER ELEVATIONS OF THE ADIRONDACKS AND GREEN MOUNTAINS
     MAINLY ABOVE 1500 FEET MEAN SEA LEVEL.

OUTLOOK 18Z SUNDAY THROUGH THURSDAY...18Z SUNDAY THROUGH 00Z
MONDAY...MVFR CEILINGS IMPROVING TO VFR BY 00Z MONDAY.

00Z MONDAY THROUGH 00Z FRIDAY...MAINLY VFR CONDITIONS EXPECTED AS
A RIDGE OF HIGH PRESSURE BUILDS EAST FROM THE GREAT LAKES WILL BE
OVER THE REGION. AN APPROACHING WARM FRONT WILL BRING A CHANCE OF
SCATTERED THUNDERSTORMS ON WEDNESDAY.
-- End Changed Discussion --

&&

.HYDROLOGY...
AS OF 440 AM SATURDAY...A WIDESPREAD RAIN EVENT WILL CONTINUE
TODAY...STORM TOTAL PRECIP VALUES OF 1 TO 2 INCHES WITH LOCALIZED
3 INCH AMOUNTS ARE POSSIBLE ACRS THE WESTERN SLOPES...PARTS OF THE
CPV...AND MTNS OF NORTH-CENTRAL VT BY SUNDAY AFTN. LOCALLY RUN
SSHP MODEL HYDROGRAPHS SUGGEST THESE TOTALS WILL LIKELY BRING
NUMEROUS SMALL STREAMS TO BANKFULL...AND SEVERAL MAINSTEM RIVERS
INTO FLOOD BY THIS AFTN INTO SUNDAY. THUS A FLOOD WATCH CONTINUE
FOR THIS POTENTIAL. AT THIS TIME...THE RIVERS OF MOST CONCERN
WOULD BE THE MISSISQUOI...LAMOILLE...OTTER...AND PASSUMPSIC IN
VERMONT...AND THE AUSABLE RIVER IN NORTHERN NEW YORK. GIVEN THE
CURRENT TRENDS IN RAINFALL TIMING AND AMOUNTS...MOST RIVER CRESTS
ARE EXPECTED TO OCCUR LATE TONIGHT OR SUNDAY MORNING.

&&

.MARINE...
-- Changed Discussion --
AS OF 420 PM SATURDAY...A LAKE WIND ADVISORY WILL REMAIN IN EFFECT
THROUGH THE DAY ON SUNDAY WITH NORTH WINDS FROM 25 TO 35 KNOTS
TONIGHT...GRADUALLY DECREASING TO 15 TO 25 KNOTS ON SUNDAY...BEFORE
LESSENING CONSIDERABLY SUNDAY NIGHT.

THESE WINDS WILL MAKE FOR VERY ROUGH CONDITIONS, WITH
WAVES ACROSS THE OPEN LAKE ULTIMATELY BUILDING UPWARDS OF 3 TO 5
FEET.

CONDITIONS WILL IMPROVE BY MONDAY WITH NORTHWEST WINDS FROM 5 TO
15 KNOTS WITH MOSTLY SUNNY SKIES AND MILDER TEMPERATURES.
-- End Changed Discussion --

&&

.CLIMATE...
WITH THE UNSEASONABLY CHILLY WEATHER EXPECTED FOR TODAY...SOME
RECORD LOW MAXIMUMS MAY BE APPROACHED OR BROKEN. THEY ARE LISTED
BELOW.

BURLINGTON:   51F (1921,1925)
MONTPELIER:   48F (1967)
MASSENA:      55F (1969,1979)
ST JOHNSBURY: 52F (1931,1925)

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR VTZ002>012-016>019.
NY...FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR NYZ028-031-034-035.

&&

$$
SYNOPSIS...TABER
NEAR TERM...NEILES/TABER
SHORT TERM...TABER
LONG TERM...EVENSON
AVIATION...WGH
HYDROLOGY...
MARINE...
CLIMATE...