-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBTV 221742
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
142 PM EDT WED MAY 22 2013

.SYNOPSIS...
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 BE
SEVERE AND PRODUCE LARGE HAIL...DAMAGING 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.

&&

.NEAR TERM /UNTIL 8 PM THIS EVENING/...
AS OF 122 PM EDT WEDNESDAY...SEVERE THUNDERSTORM WATCH ISSUED FOR
THE ENTIRE FORECAST AREA THRU 10PM.

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.

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. CLOUDS BUT NO PCPN THRU MID
AFTN...WILL TREND SKY COVER FROM OVC TO BKN BY NOONTIME.
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.

&&

.SHORT TERM /8 PM THIS EVENING THROUGH FRIDAY/...
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.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 450 AM EDT WEDNESDAY...LOTS OF UNCERTAINTY IN FCST AS WE
HEAD INTO THE HOLIDAY WEEKEND...AS LATEST TRENDS SHOW A MUCH
DEEPER/SLOWER SYSTEM FOR FRIDAY INTO SUNDAY. HAVE TRENDED TWD THE
00Z ECMWF AND 12Z GFS SOLUTIONS FOR THIS FCST...WHICH SUPPORTS
THE MENTION OF RAIN ON SATURDAY INTO SATURDAY NIGHT. IF CRNT
TRENDS CONT FOR A MUCH DEEPER AND SLOWER SYSTEM...ADDITIONAL
SHOWERS WOULD BE POSSIBLE FOR SUNDAY. LATEST 00Z ECMWF SHOWS
NORTHERN AND SOUTHERN STREAM INTERACTION BY 12Z SAT...WHICH HELPS
TO PRODUCE A CLOSED AND SLOW MOVING 5H/7H CIRCULATION OVER THE
MID ATLANTIC STATES. WHILE SFC LOW PRES TRACKS FROM NJ COAST TO
THE GULF OF MAINE BY 18Z SUNDAY. GIVEN THE POSITION AND TRACK OF
CLOSED SYSTEM AND ASSOCIATED SFC LOW PRES...EXPECT HEAVIEST QPF
TO BE JUST SOUTH AND EAST OF OUR CWA ON FRIDAY INTO SATURDAY.
HOWEVER...BACKSIDE DEFORMATION BAND OF ENHANCED MID LVL RH AND
ASSOCIATED 850 TO 500MB LIFT IS EXPECTED TO DEVELOP. ITS
EXTREMELY DIFFICULT TO DETERMINE EXACT PLACEMENT AND MOVEMENT OF
THESE BANDS AND THE ASSOCIATED PRECIP...THEREFORE WL JUST MENTION
CHC POPS FOR SATURDAY INTO SATURDAY NIGHT. FEEL SYSTEM WL SLIDE
JUST FAR ENOUGH EAST BY SUNDAY TO KEEP FCST DRY ATTM. ON
SUNDAY...AS SFC LOW PRES TRACKS INTO THE GULF OF MAINE...LOOK FOR
GUSTY NORTHWEST WINDS TO DEVELOP. LATEST SOUNDINGS SHOW 85H WINDS
BTWN 35 AND 45 KNOTS...WHICH WITH SOME MIXING WL SUPPORT GUSTS
BTWN 25 AND 35 MPH..ESPECIALLY SUNDAY AFTN. PROGGED 85H TEMPS
SUPPORT HIGHS ONLY IN THE L/M 50S MTNS TO U50S/L60S FOR SAT AND
SUNDAY. EXPECT A RAW/CLOUDY AND BREEZY TYPE DAY ON SUNDAY...WITH
BLW NORMAL TEMPS. SFC HIGH PRES WL FINALLY BUILD INTO OUR CWA ON
MONDAY INTO TUES...WITH A SLOW CLRING TREND...ALONG WITH WARMER
TEMPS. IF SKIES CLR AND WINDS BECM LIGHT...PATCHY FROST WL BE
POSSIBLE IN THE COLDER MTN VALLEYS LATE THIS WEEKEND OR EARLY
NEXT WEEK.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
-- Changed Discussion --
THROUGH 18Z THURSDAY...SHOWERS AND THUNDERSTORMS ACROSS THE
REGION WILL GENERALLY MOVE WEST TO EAST. VFR CONDITIONS WILL
DETERIORATE TO MVFR WITHIN SHOWERS AND LIFR/IFR IN AND AROUND
THUNDERSTORMS THIS AFTERNOON THROUGH THE EVENING HOURS. SOME
THUNDERSTORMS WILL CONTAIN SMALL HAIL AND DANGEROUS WIND GUSTS IN
EXCESS OF 50 KTS. KSLK ALREADY EXPERIENCING SOME TS...WITH KRUT
SEEING MVFR CIGS IN RAIN SHOWERS. KPBG/KBTV AND KMPV WILL LIKELY
SEE CONVECTION WITHIN THE NEXT 2 HRS AND CONTINUE THROUGH THE
EVENING. KMSS JUST NORTH OF BEST INSTABILITY...BUT WILL ALSO
LIKELY SEE SOME CONVECTION.

AFTER THE STORMS AND SHOWERS TAPER OFF...MAINLY AFTER
06Z...MOISTURE WHERE IS HAS RAINED WILL CONTINUE MVFR CIGS...BUT
WINDS WILL BEGIN TO PICK UP OUT OF THE S-SW WITH GRADUALLY
IMPROVING CONDITIONS TOWARDS MID MORNING.

OUTLOOK 18Z THURSDAY THROUGH MONDAY... 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
SATURDAY/SUNDAY WITH MVFR...BEFORE HIGH PRES SLOWLY BUILDS INTO
THE REGION BY EARLY NEXT WK. GUSTY NORTHWEST WINDS WL BE POSSIBLE
OVER THE WEEKEND...WITH AREAS OF LLVL TURBULENCE.
-- End Changed Discussion --

&&

.HYDROLOGY...
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.

&&

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

&&

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