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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBTV 220825
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
425 AM EDT WED MAY 22 2013

.SYNOPSIS...
-- Changed Discussion --
MOSTLY CLOUDY SKIES ARE EXPECTED ACROSS THE NORTH COUNTRY TODAY.
A WARM FRONT LIFTING NORTHEASTWARD ACROSS THE REGION LATE THIS
AFTERNOON AND EVENING WILL BRING THE POTENTIAL FOR ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS. SOME THUNDERSTORMS MAY
PRODUCE SMALL HAIL...GUSTY WINDS...AND LOCALLY HEAVY DOWNPOURS. A
SLOW-MOVING COLD FRONT WILL THEN APPROACH FROM THE EASTERN GREAT
LAKES REGION BRINGING ADDITIONAL WIDESPREAD RAINFALL AND EMBEDDED
THUNDERSTORMS DURING THURSDAY AND THURSDAY NIGHT. WHILE IT WON/T
BE RAINING CONTINUOUSLY...PERIODS OF BRIEFLY HEAVY RAIN ASSOCIATED
WITH THE SHOWERS AND THUNDERSTORMS WILL GENERALLY BRING AN
ADDITIONAL 1 TO 2 INCHES OF RAIN ACROSS THE NORTH COUNTRY THROUGH
THURSDAY NIGHT. SOME MINOR FLOODING WILL BE POSSIBLE...MAINLY
THURSDAY INTO THURSDAY NIGHT WITH THE MOST WIDESPREAD RAINFALL.
-- End Changed Discussion --

&&

.NEAR TERM /UNTIL 8 PM THIS EVENING/...
-- Changed Discussion --
AS OF 418 AM EDT WEDNESDAY...UNSETTLED PATTERN CONTINUES ACROSS THE
NORTH COUNTRY IN VCNTY OF E-W ORIENTED FRONTAL ZONE WHICH REMAINS
DRAPED ACROSS THE REGION. SFC TROUGH AND 850MB TEMP GRADIENT
SUGGESTS SYNOPTIC FRONTAL ZONE IS UP NEAR THE INTL BORDER...BUT
GIVEN THE WIDESPREAD CONVECTION THAT HAS OCCURRED IN SEVERAL WAVES
DURING THE PAST 6-12 HOURS...THE EFFECTIVE FRONTAL POSITION
EXTENDS ACROSS THE SRN TIER OF NY INTO NWRN CT WHERE LARGE
MESOSCALE COLD POOL HAS BEEN ESTABLISHED.

REMAINING RAIN SHOWERS ACROSS THE NORTH COUNTRY DEPART EWD INTO NH
BY 10Z THIS MORNING. WILL SEE PATCHY FOG AROUND THRU 12Z GIVEN SATURATED
LOW-LEVEL CONDITIONS AND GENERALLY LIGHT WINDS. WEAK SFC LOW ACROSS
NRN NY WILL GENERALLY DISSIPATE THRU THE REMAINDER OF THIS MORNING.
THERE ARE SLIGHT 700-500MB HEIGHT RISES THIS MORNING THRU EARLY
AFTN...AND ABSENCE OF LOW-LEVEL CONVERGENCE SUGGESTS ADDITIONAL
RAINFALL IS UNLIKELY THRU ABOUT 19Z. THEREAFTER...THERE IS A SWLY
BACKING AND STRENGTHENING OF 850MB FLOW ACROSS WRN PA INTO CENTRAL
NY PER MODEL GUIDANCE. FEEL THAT REMNANT OUTFLOW BOUNDARY ACROSS
CENTRAL NY WILL ENHANCE ISENTROPIC ASCENT LATE IN THE DAY ACROSS THE
ADIRONDACKS AND S-CENTRAL VT...ALLOWING FOR DEVELOPMENT OF SHOWER
AND TSTM ACTIVITY. THE 00Z NAM SHOWS DEVELOPMENT OF MUCAPE OF
500-1000 J/KG ACROSS ALL BUT NERN PORTION OF THE FORECAST AREA
21-00Z. RAP SOUNDINGS SHOW A BIT MORE INSTABILITY...UP TO 1500
J/KG...THOUGH SFC DEWPOINTS MAY BE A BIT OVERDONE HERE. BASED ON
CONSENSUS OF THE MODELS INCLUDING LOCALLY RUN 4KM WRF...LOOKING
FOR DEVELOPMENT OF A FEW STRONG LATE DAY/EVENING TSTMS AS WELL.
SPC CALIBRATED SVR PROBABILITIES AND DAY 1 OUTLOOK SUPPORT A FEW
SEVERE STORMS...AND MENTIONED GUSTY WINDS AND SMALL HAIL IN THE
FORECAST AND HWO FOR LATE AFTN/EVENING. DEEP LAYER (SFC-6KM) SHEAR
EXCEEDS 40 KTS AND IS SUPPORTIVE OF SOME LONG-LIVED UPDRAFTS. 00Z
ALB SOUNDING SHOWED PW VALUES OF 1.52"...AND NWD ADVECTION OF THIS
MOIST AIR MASS WILL ALSO YIELD LOCALLY HEAVY DOWNPOURS WITH THE
CONVECTION LATE THIS AFTN INTO THIS EVENING. AFTN TEMPS TODAY
HIGHLY DEPEND ON SOME SUNNY BREAKS DURING THE LATE MORNING-MID
AFTN PERIOD. ANTICIPATE SOME INTERVALS OF SUN TODAY...AND WITH
850MB TEMPS OF +14C COULD WARM QUICKLY DURING THE EARLY AFTN. HIGH
TEMPERATURES IN THE VALLEYS GENERALLY IN THE MID TO UPR 70S...BUT
COULD REACH 80F IF WE GET A BIT MORE SUNSHINE AND INSOLATIONAL
HEATING.
-- End Changed Discussion --

&&

.SHORT TERM /8 PM THIS EVENING THROUGH FRIDAY/...
-- Changed Discussion --
AS OF 418 AM EDT WEDNESDAY...DEEP-LAYER SWLY FLOW AND WARM ADVECTION
CONTINUES OVERNIGHT...WITH BEST ISENTROPIC ASCENT GRADUALLY
SHIFTING NORTH AND EAST. HAVE CARRIED LIKELY POPS FOR WIDESPREAD
SHOWERS AND CONTINUED EMBEDDED TSTMS. SOME DECREASE IN CAPE
OVERNIGHT...SO KEPT ENHANCED WIND/HAIL WORDING JUST THRU THE
EVENING HOURS. LOWS WILL BE ON THE WARM SIDE TONIGHT WITH 60S
DEWPOINTS IN PLACE ALONG WITH CLOUDS AND S-SW WINDS ALL NIGHT. LOW
TEMPS WILL MAINLY BE IN THE UPR 50S TO LOWER 60S.

THURSDAY WILL PRODUCE OUR MOST WIDESPREAD RAINFALL AS COLD FRONT AND
ASSOCIATED POSITIVE TILT 500MB TROUGH BEGINS TO SHIFT SLOWLY SEWD
ACROSS THE FORECAST AREA. MOIST AND MARGINALLY UNSTABLE AIR MASS
WILL SUPPORT SEVERAL BANDS OF SLOW MOVING CONVECTION ALONG/IN
ADVANCE OF THE COLD FRONT. GIVEN THE SETUP...MOST OF THE NWP QPF
LOOKED ON THE LOW SIDE GIVEN EVOLUTION AND MOIST AIR MASS IN
PLACE. TRENDED CLOSER TO HIGHER ECMWF QPF WITH WIDESPREAD 1+"
RAINFALL AMTS ACROSS THE CWA. SOME OF THIS HEAVY RAIN CONTINUES
INTO THURSDAY NIGHT...ESPECIALLY CENTRAL AND ERN VT. CAN/T RULE
OUT LOCALIZED 2" RAINFALL AMTS BEFORE THINGS LIGHTEN UP EARLY
FRIDAY. SOME MINOR FLOODING IS POSSIBLE...REFER TO HYDRO SECTION
BELOW. HIGHS THURSDAY GENERALLY IN THE MID 70S. EPISODES OF
SHOWERS/TSTMS EXPECTED UNDER CLOUDY SKIES.

FRIDAY...LIKELY POPS FOR RAIN SHOWERS IN THE MORNING...THEN
SLOW/GRADUAL DRYING FROM NW-SE ACROSS THE REGION. SHOULD SEE SOME
PARTIAL SUNSHINE LATE IN THE DAY FROM THE CHAMPLAIN VALLEY WWD.
COOLER TEMPS WITH HIGHS IN THE LOW-MID 60S.
-- End Changed Discussion --

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 225 PM EDT TUESDAY...DEPARTING LOW PRESSURE SYSTEM WILL
HAVE POSITIVELY TILTED UPPER LEVEL TROUGH MOVE OVER THE NORTH
COUNTRY ON FRIDAY...KEEPING CHC OF SHOWERS OVER MUCH OF THE AREA.
LATE FRIDAY IN TO FRIDAY NIGHT...TROUGH LOOKS TO TILT NEUTRAL TO
NEGATIVE AS THE SFC LOW PUSHES OFF THE NEW ENGLAND COAST. SFC LOW
TRAVERSES NEWD NEAR NEWFOUNDLAND...KEEPING BACK/WRN EDGE OF
PRECIP NEAR VT...THEREFORE HAVE KEPT SLGT CHC POPS OVER VT FRIDAY
NIGHT THROUGH FIRST HALF OF SATURDAY. AS HIGH PRESSURE BUILDS
OVER SW HUDSONS BAY...EXTENDING SWD OVER THE CENTRAL GREAT
LAKES...A SHORTWAVE ROTATING ABOUT THE UPPER LEVEL LOW OVER NEW
ENGLAND WILL BE FAIRLY DRY BUT BRING CLOUDS FOR THE REST OF
SATURDAY INTO SATURDAY NIGHT. ON SUNDAY...SOME TROUGHINESS
REMAINING OVER ERN ZONES...WITH CLOUDS OVER MOST OF VT. THE SFC
HIGH PRESSURE AND SOME UPPER LEVEL RIDGING WILL TAKE HOLD OF THE
REGION FOR THE REST OF THE PERIOD.

BELOW NORMAL MAX TEMPS WILL GRADUALLY TREND WARMER THROUGHOUT THE
PERIOD WITH MIN TEMPS GENERALLY IN THE 40S.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
THROUGH 06Z THURSDAY...ONCE AGAIN ANOTHER CHALLENGING AVIATION
FCST WITH REGARDS TO POTENTIAL IFR CIGS/VIS THRU THIS MORNING.
CRNT OBS SHOW TAF SITES RANGING FROM VFR AT RUT TO MVFR AT
BTV/SLK/MSS AND IFR AT MPV/PBG. RADAR SHOWS BAND OF MODERATE RAIN
ACRS THE CPV...WHICH WL BE EAST AND SOUTH OF MPV/RUT TAF SITES BY
07Z. GIVEN 925MB WINDS OF 25 TO 35 KNTS...EXPECT STRATUS
DEVELOPMENT WITH IFR LIKELY AT MPV/MSS/SLK BY 08Z THIS MORNING.
MEANWHILE...SOUNDINGS SHOW PLENTY OF BL RH AT RUT/BTV/PBG...BUT
FEEL MVFR CONDITIONS WITH PERIODS OF IFR CIGS CAN BE EXPECTED TWD
MORNING. ANY IFR CIGS SHOULD SLOWLY DISSIPATE BY 15Z AT
MPV/MSS/SLK...AS SOUTHERLY WINDS DEVELOP. SFC BOUNDARY CONTS TO BE
DRAPED ACRS OUR TAF SITES THIS AFTN. THIS FRNT...COMBINED WITH SFC
HEATING/INSTABILITY WL PRODUCE MORE SCATTERED/NUMEROUS
SHOWERS/STORMS AFT 21Z TODAY...WITH MVFR TO BRIEF PERIODS OF IFR
CIGS/VIS LIKELY IN THE HEAVIER STORMS. IN ADDITION...BRIEF GUSTY
WINDS WL BE POSSIBLE. THIS SHOWERS WL WEAKEN TWD LATE EVENING WITH
AREAS OF LOW CLOUDS AND PATCHY FOG LIKELY DEVELOPING BY 06Z
THURSDAY...ESPECIALLY MSS/SLK/MPV.

OUTLOOK 06Z THURSDAY THROUGH SUNDAY...
UNSETTLED WX WITH OCCASIONAL SHOWERS/STORMS WL CONT FOR THURSDAY
INTO FRIDAY ACRS OUR TAF SITES. THE STRONGER SHOWERS/STORMS ON
THURS AFTN/EVENING ASSOCIATED WITH A SFC COLD FRNT WL PRODUCE MVFR
CONDITIONS...WITH BRIEF PERIODS OF IFR LIKELY. ALSO...ANY STORMS
WL HAVE THE POTENTIAL TO PRODUCE GUSTY SFC WINDS UP TO 40 MPH. AREAS
OF FOG AND LOW CLOUDS WL BE POSSIBLE ON THURSDAY NIGHT...WITH SOME
LOCALIZED IFR/LIFR LIKELY. SCATTERED SHOWERS MAY LINGER INTO EARLY
SATURDAY MORNING...BEFORE HIGH PRES SLOWLY BUILDS INTO THE REGION
BY SUNDAY. GUSTY NORTHWEST WINDS WL BE POSSIBLE OVER THE
WEEKEND...WITH AREAS OF LLVL TURBULENCE.

&&

.HYDROLOGY...
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430AM WEDNESDAY...WIDESPREAD 1.0" TO 1.5" RAINFALL (WITH LOCALLY
HIGHER AMTS) HAS OCCURRED ACROSS THE NORTH COUNTRY DURING THE PAST
24-30 HOURS ASSOCIATED WITH SEVERAL EPISODES OF HEAVY SHOWERS AND
TSTMS. AN ADDITIONAL 1-2" RAINFALL IS FORECAST BETWEEN LATE
AFTN/EVENING SHOWERS AND TSTMS AND THE MORE WIDESPREAD RAIN AND
EMBEDDED TSTMS ON THURSDAY. WHILE ANTECEDENT SOIL CONDITIONS HAVE
BEEN DRY...AND VEGETATION IS FULLY ACTIVE...THE ADDITIONAL
RAINFALL WILL EVENTUALLY BRING THE POTENTIAL FOR STREET/POOR
DRAINAGE FLOODING. ASSOCIATED MINOR FLOODING WOULD MOST LIKELY
OCCUR DURING THE DAY THURSDAY AND INTO THURSDAY NIGHT. MAIN-STEM
RIVER FLOODING IS NOT FORECAST...BUT MAY NEED TO WATCH SOME OF THE
SMALLER RIVERS AND STREAMS THAT COULD LOCALLY EXCEED BANKFUL LATER
THURSDAY AND THURSDAY NIGHT.
-- End Changed Discussion --

&&

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

&&

$$
SYNOPSIS...BANACOS
NEAR TERM...BANACOS
SHORT TERM...BANACOS
LONG TERM...KGM
AVIATION...TABER
HYDROLOGY...BANACOS