-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBTV 241442
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
1042 AM EDT FRI MAY 24 2013

.SYNOPSIS...
A DEVELOPING COASTAL SYSTEM WILL BRING ADDITIONAL RAINFALL AND MUCH
COOLER TEMPERATURES TO THE NORTH COUNTRY THIS WEEKEND. THE ADDITIONAL
RAINFALL WILL CAUSE SIGNIFICANT RISES ON LOCAL WATERWAYS...WITH SOME
RIVER FLOODING POSSIBLE. TEMPERATURES WILL BE 15 TO 20 DEGREES BELOW
NORMAL WITH SOME HIGH ELEVATION ACCUMULATING SNOWFALL POSSIBLE ON
SATURDAY INTO SUNDAY. A WARMING AND DRYING TREND WILL OCCUR BY EARLY
NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
AS OF 1042 AM EDT FRIDAY...MINOR UPDATES TO T/TD/POPS AS WE HEAD
INTO THE LATE MORNING AND AFTERNOON HOURS. TEMPERATURES GENERALLY
STEADY FROM HERE ON OUT...GENERALLY HOLDING IN THE 40S. DID OPT TO
RAISE POPS TO NEARLY CATEGORICAL IN ALL AREAS (I.E. > 80%) PER
LATEST RADAR COVERAGE AND HI-RES MODEL 0-12 HR OUTPUT. RAIN WILL
CERTAINLY NOT BE AS EXCESSIVE AS WE SAW YESTERDAY IN
SPOTS...NONETHELESS IT WILL BE A RAW...BREEZY AND WET DAY FOR MOST
LOCALES WITH AN ADDITIONAL 0.10 TO 0.50 INCHES OF QPF POSSIBLE BY
DAY`S END. PRIOR DISCUSSION FOLLOWS...

UPDATED FCST TO DROP TEMPS BY 3 TO 5 DEGREES ACRS THE SLV AND 1 TO
3 DEGREES OVER THE CPV. ALSO...MADE SEVERAL TWEAKS TO POPS BASED
ON CRNT RADAR DATA. THE COMBINATION OF LLVL CAA AND UPSLOPE FLW WL
PRODUCE OCCASIONAL RAIN ACRS MOST OF THE FA TODAY. HIGHEST
POPS/QPF WL BE ALONG THE WESTERN SLOPES AND NORTHERN DACKS.
ADDITIONAL RAINFALL AMOUNTS TODAY WL BE BTWN 0.10 AND 0.40". TEMPS
WL REMAIN NEAR STEADY IN THE L/M 40S MTNS TO NEAR 50 SLV/CPV.
ALSO...GUSTY NORTHWEST WINDS OF 10 TO 20 MPH CAN BE
ANTICIPATED...ADDING AN EXTRA CHILL TO THE AIR.

A LONG DURATION RAIN WITH SOME ACCUMULATING MTN
SNOW EVENT EXPECTED TODAY THROUGH SUNDAY. ADDITIONAL RAINFALL
AMOUNTS OF 1 TO 2 INCHES WITH LOCALIZED 3 INCHES CAN BE EXPECTED
BY SUNDAY...WITH SHARP RISES EXPECTED ON AREA WATERWAYS.

WATER VAPOR SHOWS A COMPLEX DIGGING MID/UPPER LVL TROF ACRS THE EASTERN
CONUS THIS MORNING...AS BOTH NORTHERN/SOUTHERN STREAM ENERGY ARE
PHASING. NOTICING LARGE PLUME OF SUB-TROPICAL MOISTURE ADVECTING INTO
THE MID ATLANTIC/SNE AS TROF BECMS NEGATIVELY TILTED. ALSO...DEVELOPING
MID/UPPER LVL DRY SLOT IS ROTATING ACRS THE SE CONUS. THESE FEATURES
COMBINED WITH A DUAL 25H JET STRUCTURE...SIMILAR TO A WINTER-TIME
SYNOPTIC SYSTEM WL PRODUCE A COMPLEX WX SCENARIO ACRS OUR FA THIS WKND.
MEANWHILE...AT THE SFC A SHARP COLD FRNT IS MOVING ACRS OUR
CWA...HELPING TO ENHANCE THE LLVL THERMAL GRADIENT. THIS WL EVENTUALLY
PUSH TWD THE COAST...WITH COASTAL LOW PRES MOVING ALONG THE BOUNDARY.

FCST CHALLENGE TODAY WL BE AREAL COVERAGE/INTENSITY OF
RAINFALL...ASSOCIATED WITH TIGHT THERMAL GRADIENT AND POST-FRONTAL
MOISTURE. EXPECT OCCASIONAL WIDESPREAD LIGHT RAIN TODAY...AS FA IS BTWN
SYSTEMS. GFS/NAM SHOW BEST 7H FGEN FORCING AND ASSOCIATED Q-VECTOR
CONVERGENCE DEVELOPING ACRS OUR CWA AFT 18Z. IN ADDITION...WARM MOIST
CONVEYOR BELT SHOULD BE EAST OF OUR CWA...ALONG WITH HEAVIEST QPF. WL
STILL MENTION CAT POPS...BUT QPF AMOUNTS SHOULD RANGE BTWN 0.10 AND
0.40" TODAY. TEMPS TODAY WITH BREEZY NORTH WINDS WL STRUGGLE IN THE
U30S TO M40S MTNS TO L50S CPV/SLV TO NEAR 60F AT VSF.
-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
AS OF 430 AM EDT FRIDAY...POTENT NORTHERN STREAM S/W ENERGY WL ROUND MID/UPPER
LVL TROF BASE AND DEVELOP SFC LOW PRES NEAR CAPE COD BY 00Z THIS
EVENING. THIS SYSTEM WL QUICKLY BECM VERTICALLY AND NEGATIVELY
STACKED AS 7H/5H CIRCULATIONS DEEPEN AND BECOME CLOSED. THE
CYCLONIC CIRCULATION WL ADVECT PLENTY OF DEEP ATLANTIC MOISTURE
BACK INTO OUR FA BTWN 850 AND 700MB...WHILE A VERY COLD AIR MASS IS
PULLED INTO THE SYSTEM FROM CENTRAL CANADA. THIS VERY TIGHT
THERMAL GRADIENT...COMBINED WITH FAVORABLE RRQ OF 25H JET WL
PRODUCE A WIDESPREAD MODERATE TO HEAVY PRECIP EVENT ACRS MOST OF
OUR CWA...ESPECIALLY EASTERN DACKS INTO VT. THIS SYNOPTIC SCALE
COASTAL SYSTEM WL HAVE A VERY WINTER-TIME THERMAL/JET STRUCTURE.
BOTH GFS/ECMWF IN GOOD AGREEMENT WITH PLACEMENT OF BACKSIDE
DEFORMATION BAND OF ENHANCED 850 TO 500MB RH AND ASSOCIATED DEEP
LAYER OMEGA FROM 18Z TODAY THRU 00Z SUNDAY. THIS BAND OF FAVORABLE
LIFT/MOISTURE MOVES VERY LITTLE OVER THE NEXT 12 TO 24 HRS...WHICH
WL PRODUCE A LONG DURATION PRECIP EVENT. THE FGEN FORCING AND
DEFORMATION ZNS NW OF THE CLOSED SYSTEM IS VERY SIMILAR TO WHAT
YOU SEE IN A WINTER TIME COASTAL...ALONG WITH FAVORABLE BACKSIDE
UPSLOPE PARAMETERS.

RAINFALL...EXPECT STORM TOTAL QPF AMOUNTS TO RANGE FROM 0.25 TO 0.75"
FOR THE SLV/WESTERN DACKS TO 1.0 TO 2.0" CPV/EASTERN DACKS TO DOWNSLOPE
REGIONS OF THE NEK TO 1.50 TO 2.5"...WITH LOCALIZED HIGHER AMOUNTS MTNS
OF NORTH/CENTRAL VT BY 00Z MONDAY. THESE ANTICIPATED RAINFALL AMOUNTS
OVER A 24 TO 48 PERIOD WL CAUSE ADDITIONAL RISES ON LOCAL
WATERWAYS...WITH SOME ADDITIONAL RIVER AND LOW LYING FLOODING POSSIBLE.
NOTE...THIS WL BE A LONG DURATION EVENT WITH STEADY/MODERATE RAINFALL
RATES...WHICH IS DIFFERENT FROM THURSDAY EVENT. STILL SOME UNCERTAINTY
WITH REGARDS TO TIMING AND PLACEMENT OF HEAVIEST QPF...THEREFORE NO
FLOOD WATCH WL BE ISSUED ATTM.

SNOWFALL...STILL HAVING A HARD TIME BELIEVING ACCUMULATING
SNOWFALL IS POSSIBLE ACRS THE MTNS ABOVE 2500 FT ON SAT INTO
SUNDAY. GFS/NAM BUFKIT SOUNDINGS AND ECMWF PROFILES HAVE INDICATED
THIS POTENTIAL FOR THE PAST COUPLE OF DAYS...AS COLDER AIR IS
WRAPPED INTO THE SYSTEM. PROGGED 85H TEMPS DROP BLW 0C BY
TONIGHT...WITH 1000 TO 500MB THICKNESS VALUES BLW 540DAM. THIS
COMBINED WITH SOME COOLING FROM STRONG DYNAMICS WL HELP TO PRODUCE
SOME ACCUMULATING SNOWFALL ACRS THE DACKS AND GREEN MTNS ABOVE
2500FT. WL TRY TO SHOW IN GRIDS...BUT IMPACTS WL BE MINIMAL GIVEN
THE HIGH SNOW LEVELS. THINKING A DUSTING TO SEVERAL INCHES OF
HEAVY WET SNOW WL BE POSSIBLE...WITH 6 INCHES OR SO FOR THE
SUMMITS FROM MT MANSFIELD TO JAY PEAK AND ACRS PARTS OF THE
EASTERN DACKS BY SUNDAY. BEST CHC FOR ACCUMULATING SNOWFALL WL BE
SATURDAY NIGHT/SUNDAY MORNING.

TEMPS/WINDS...PROGGED 85H TEMPS NEAR 0C...COMBINED WITH PLENTY OF
CLOUDS/PRECIP AND A NORTH WIND WL RESULT IN HIGHS ONLY IN THE M/U 30S
MTNS TO M/U 40S SLV/CPV ON SAT/SUNDAY. THE TRENDS HAVE BEEN COOLER AND
COOLER IN THE GUIDANCE. EXPECT LITTLE CHANGE IN TEMPS ON SAT
NIGHT...WITH PRECIP/CLOUDS...THINKING L/M 30S MTNS TO NEAR 40F CPV/SLV.
EXPECT A COLD/BLUSTERY AND WET DAY ON SUNDAY FOR MARATHON
ACTIVITIES IN BURLINGTON.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 430 AM EDT FRIDAY...UPPER LOW FINALLY STARTS TO LIFT NORTHEAST OUT
OF THE AREA SUNDAY NIGHT AND MONDAY...THUS BRINGING ANY
PRECIPITATION QUICKLY TO AN END. SURFACE HIGH PRESSURE BUILDS IN
FOR A RETURN TO DRY WEATHER. NORTHWEST FLOW ALOFT WILL EXIST EARLY
NEXT WEEK FOR A GRADUAL WARMING TREND...BUT UPPER RIDGING BUILDS
IN BY MIDWEEK AND THIS WILL ALLOW FOR A MORE NOTICEABLE WARMING
TREND WITH ABOVE NORMAL TEMPERATURES EXPECTED. FRONTAL BOUNDARY
LIFTS NORTHEAST INTO THE AREA BY MIDWEEK AND COMBINED WITH
INCREASING INSTABILITY FROM THE WARMER AND MORE MOIST AIR
MASS...POTENTIAL FOR SOME SHOWERS AND THUNDERSTORMS WILL EXIST
WEDNESDAY INTO THURSDAY.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
THROUGH 12Z SATURDAY...EXPECT AN EXTENDED PERIOD OF MVFR AND IFR
CONDITIONS ACROSS NORTHERN NEW YORK AND VERMONT DUE TO LOW
CEILINGS AND VISIBILITIES AS WELL AS LIGHT RAIN. THERE WILL ALSO
BE BRIEF PERIODS OF LIFR CEILINGS AS ABUNDANT LOW LEVEL MOISTURE
WILL EXIST OVER THE AREA. THE WIND WILL BECOME NORTHWEST ALL AREAS
AT SPEEDS OF 10 KNOTS OR LESS THROUGH MUCH OF THE PERIOD.

OUTLOOK 12Z SATURDAY THROUGH TUESDAY...THE COMBINATION OF A SFC
BOUNDARY AND ASSOCIATED LOW PRESSURE WILL KEEP SHOWERS IN THE TAF
SITES THRU THE WEEKEND. THESE SHOWERS WILL PRODUCE PERIODS OF MVFR
CIGS/VSBYS WITH SOME IFR CONDITIONS POSSIBLE...ESPECIALLY AT
NIGHT. IN ADDITION...BREEZY NORTHWEST WINDS WILL DEVELOP AS SFC
LOW PRES TRACKS INTO THE GULF OF MAINE ON SUNDAY. A SLOW CLEARING
TREND IS ANTICIPATED ON MONDAY...W/ VFR CONDITIONS TUESDAY.

&&

.HYDROLOGY...
AS OF 430 AM FRIDAY...A LONG DURATION MODERATE TO HEAVY RAINFALL EVENT
IS ANTICIPATED FROM TODAY THROUGH SUNDAY...WITH SIGNIFICANT RISES
ON LARGE STEM RIVERS. EXPECT STORM TOTAL QPF AMOUNTS TO RANGE FROM
0.25 TO 0.75" FOR THE SLV/WESTERN DACKS TO 1.0 TO 2.0" CPV/EASTERN
DACKS TO DOWNSLOPE REGIONS OF THE NEK TO 1.50 TO 2.5"...WITH
LOCALIZED HIGHER AMOUNTS MTNS OF NORTH/CENTRAL VT BY 00Z MONDAY.
THIS RAINFALL COMBINED WITH RECENT RAIN FROM CONVECTION WL PRODUCE
ADDITIONAL MINOR LOW LYING FLOODING...WITH THE POTENTIAL FOR
SEVERAL RIVERS TO APPROACH FLOOD STAGE BY SUNDAY. NO FLOOD WATCH
WILL BE ISSUED WITH THIS PACKAGE...BUT IF CRNT TRENDS CONTINUE
ANOTHER FLOOD WATCH MAYBE NEEDED FOR THE WEEKEND.

&&

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

&&

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