Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 301413 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 1013 AM EDT SAT MAY 30 2015 .SYNOPSIS... A SLOW MOVING COLD FRONT WILL PRODUCE OCCASIONAL SHOWERS AND THUNDERSTORMS THIS AFTERNOON ACROSS THE NORTH COUNTRY. LOCALIZED HEAVY DOWN POURS...FREQUENT LIGHTNING...AND GUSTY WINDS WILL BE POSSIBLE WITH ANY THUNDERSTORMS. A WIDESPREAD RAINFALL IS EXPECTED TONIGHT INTO SUNDAY...WITH ADDITIONAL SHOWERS ON MONDAY. TEMPERATURES WILL WARM BACK INTO THE 70S AND 80S TODAY...WITH BREEZY SOUTH WINDS...BUT A COOLER AND WETTER PATTERN DEVELOPS FOR SUNDAY INTO EARLY THIS UPCOMING WEEK. && .NEAR TERM /UNTIL 7 PM THIS EVENING/...
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AS OF 956 AM EDT SATURDAY...FORECAST REMAINS ON TRACK WITH SCATTERED CONVECTIVE STORMS MID AFTERNOON THRU EARLY EVENING WITH HEAVY DOWNPOURS AND LOCALIZED DAMAGING WINDS POSSIBLE. MAINLY 3-5 PM ACROSS NRN NY AND 4-7PM ACROSS WRN/CENTRAL VT FOR STRONGEST T-STORM THREAT. SYNOPSIS: NORTH COUNTRY IS EMBEDDED WITHIN WARM/HUMID LOW-LEVEL AIR MASS WITH MODERATELY STRONG SOUTHERLY TO SOUTHWESTERLY GRADIENT FLOW IN PLACE (BETWEEN SURFACE ANTICYCLONE EAST OF NEW ENGLAND AND STRONG FRONTAL BNDRY ACROSS SWRN QUEBEC INTO SERN ONTARIO). SATELLITE IMAGERY SHOWS MID-LEVEL CLOUDS GRADUALLY ERODING AT 1330Z...AND AREAS WITH FULL SUN IN THE ST. LAWRENCE VALLEY ALREADY CLIMBING INTO THE LOWER 80S AT 14Z WITH SFC DEWPOINTS IN THE LOW TO MID 60S. EXPECTATION BASED ON BTV-4KM WRF AND NCAR 3KM WRF ENSEMBLE IS FOR MULTICELLULAR CONVECTION TO DEVELOP ACROSS CENTRAL NY AND SPREAD NEWD ACROSS NRN NY BY MID-AFTERNOON. GENERALLY LOOKING AT SBCAPE VALUES BETWEEN 1000-2000 J/KG AREAWIDE WITH LITTLE OR NO CIN ACROSS NRN NY INTO THE CHAMPLAIN VALLEY BY 18Z. FORCING IS NOT PARTICULARLY STRONG, WITH BETTER CONVERGENCE TO OUR NW ALONG THE FRONTAL ZONE. DEEP-LAYER SHEAR AND MID- LEVEL LAPSE RATES ARE MARGINAL FOR ORGANIZED SVR THREAT...BUT AMPLE LOW-LEVEL BULK SHEAR WITH 850MB LOW-LEVEL JET AND STEEP SFC BASED LAPSE RATES (FROM INSOLATIONAL HEATING) WILL RESULT IN SOME ROBUST UPDRAFTS THIS AFTERNOON. LOCALIZED DAMAGING WINDS REMAIN POSSIBLE WITH A FEW STRONGER CORES/DOWNDRAFTS. WITH PW VALUES 1.75-1.90" ...ALSO MAINTAINED MENTION OF LOCALLY HEAVY DOWNPOURS WITH T-STORMS. SOME BACKBULIDING POSSIBLE WITH CORFIDI VECTORS LESS THAN 5 KTS...SO WILL NEED TO MONITOR FOR TRAINING CELLS (THOUGH ANTECEDENT CONDITIONS ARE RELATIVELY DRY FOR ANY RIVER CONCERNS...MAIN ISSUE WOULD BE POOR DRAINAGE FLOODING OR RAPID RISES ON STREAMS IN STEEPER TERRAIN AREAS. LOCALIZED HEAVY RAINFALL IS POSSIBLE WITH ANY STORM. THINKING WIDESPREAD RAINFALL OF 0.50 TO 1.50 WITH LOCALIZED AMOUNTS NEAR 3.0" POSSIBLE. SOME MINOR POOR DRAINAGE/URBAN FLOODING IS POSSIBLE ASSOCIATED WITH THE HIGHER RAINFALL RATES. SOUTH TO SW WINDS WILL REMAIN 15-25 MPH WITH GUSTS 30-35 MPH (HIGHEST IN THE CHAMPLAIN VALLEY AND ST. LAWRENCE VALLEY) THROUGH MID AFTERNOON. FRONTAL BNDRY ARRIVES IN THE ST. LAWRENCE VALLEY BY 02-03Z...WITH NWLY WIND SHIFT AT THAT TIME.
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&& .SHORT TERM /7 PM THIS EVENING THROUGH MONDAY/...
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AS OF 330 AM EDT SATURDAY...SHOWERS AND ISOLATED THUNDERSTORMS WILL QUICKLY DECREASE IN AREAL COVERAGE AND INTENSITY AFT 04Z...WITH MAINLY LIGHT STRATO FORM RAIN LIKELY. SFC BOUNDARY IS EXPECTED TO BECOME STATIONARY ALONG THE MID ATLANTIC STATES/SOUTHERN NEW ENGLAND ON SUNDAY...WHILE ADDITIONAL ENERGY/MOISTURE NOW OVER THE MS RIVER VALLEY STREAMS INTO OUR REGION. THIS POTENT S/W ENERGY AND ASSOCIATED MID/UPPER LVL TROF WILL HELP TO DEVELOP SFC LOW PRES...WHICH WILL TRAVEL ALONG THE BOUNDARY AND ENHANCE RAINFALL ACRS OUR REGION ON SUNDAY AFTN INTO MONDAY. BOTH GFS/NAM SHOW IMPRESSIVE NOSE OF 85H JET OF 40 TO 50 KNOTS LIFTING ACRS CENTRAL NY ON SUNDAY EVENING...ALONG WITH GOOD DEEP LAYER THETA E ADVECTION...AND RRQ OF 25H JET. THIS MOISTURE AND STRONG LIFT WILL PRODUCE ANOTHER ROUND OF MODERATE TO HEAVY RAINFALL. GIVEN THE LACK OF INSTABILITY PER SOUNDINGS...AS WE ARE ON THE COLD SIDE OF FRONT...WITH JUST SOME WEAK ELEVATED INSTABILITY...NOT EXPECTING EXTREME RAINFALL RATES. HOWEVER...IF BOUNDARY LIFTS FURTHER NORTH THAN EXPECTED...SOME HIGHER PRECIP RATES WILL BE POSSIBLE. GIVEN THE AVAILABLE MOISTURE AND EXPECTED LIFT...ANOTHER WIDESPREAD 1 TO 2 INCHES OF RAINFALL IS POSSIBLE SUNDAY NIGHT INTO MONDAY. THIS WILL CAUSE SOME ADDITIONAL RISES ON LOCAL STREAMS AND RIVERS...BUT ONCE AGAIN NOT EXPECTING ANY LARGE STEM RIVER FLOODING. TEMPS WILL BE BELOW NORMAL ON SUNDAY AND MONDAY WITH HIGHS GENERALLY IN THE 50S/60S AND LOWS IN THE 40S TO MID 50S. GIVEN CLOUDS AND PRECIP...AND NORTH WINDS THE DIURNAL CHANGE WILL BE LIMITED.
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&& .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AS OF 415 AM EDT SATURDAY...RAIN THREAT CONTINUES MONDAY NIGHT INTO TUESDAY. WEAK SURFACE LOW PASSING JUST SOUTH OF NEW ENGLAND... WITH TROUGH EXTENDING NORTH OF THE LOW INTO FORECAST AREA. MEANWHILE...RATHER VIGOROUS UPPER LOW WILL BE TRACKING FROM GREAT LAKES MONDAY NIGHT INTO FORECAST AREA DURING TUESDAY. CHANCES FOR RAINFALL EXPECTED TO BE HIGHEST OVER VERMONT...WHERE SOME ADDITIONAL HEAVY RAINFALL POSSIBLE. THIS IS ESPECIALLY TRUE IF ECMWF IS CORRECT...WHICH IS SLOWER WITH EASTWARD SHIFT OF THE SURFACE FEATURE AND THE HIGHER PRECIPITABLE WATER VALUES. IT WILL REMAIN COOL ON TUESDAY WITH THE WET WEATHER AND CLOUDS...WITH HIGHS IN THE UPPER 50S TO MID 60S. UPPER LOW MAKES ITS WAY EAST ACROSS THE REGION TUESDAY NIGHT AND THEN HEADS INTO EASTERN CANADA WEDNESDAY. CHANCE OF SHOWERS CONTINUES TUESDAY NIGHT...BUT DRIER CONDITIONS RETURN FOR WEDNESDAY AS HEIGHTS RISE WITH DEPARTURE OF UPPER LOW WHILE SURFACE HIGH PRESSURE BUILDS INTO THE REGION. LARGE AREA OF HIGH PRESSURE THEN EXPECTED TO PREVAIL FOR THURSDAY AND FRIDAY. AIRMASS WARMING WITH TIME...SO LOOK FOR TEMPERATURES TO RETURN TO ABOVE NORMAL READINGS LATER IN THE WEEK WITH HIGHS IN THE UPPER 70S AND LOWER 80S. NIGHTTIME LOWS WILL RANGE MOSTLY FROM THE MID 40S TO MID 50S. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... THROUGH 12Z SUNDAY...VFR FOR MUCH OF TODAY WITH CONDITIONS TRENDING MVFR LATER TODAY INTO TONIGHT ALONG WITH INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS. OTHER AVIATION CONCERN WILL BE GUSTY SOUTHERLY WINDS TODAY. BROKEN MID DECK OF CLOUDS ACROSS THE FORECAST AREA EARLY THIS MORNING. EXPECT INCREASING CLOUDS TODAY WITH GRADUALLY LOWERING CEILINGS IN ADVANCE OF A COLD FRONT. STRENGTHENING GRADIENT AHEAD OF THE FRONT WILL ALLOW FOR SOUTHERLY WINDS TO INCREASE INTO THE 12-18 KT RANGE WITH GUSTS 25-30 KTS. SHOWER/THUNDERSTORM COVERAGE WILL INCREASE AFTER 18Z ACROSS NORTHERN NEW YORK AND AFTER 21Z ACROSS VERMONT. SOME STORMS COULD TURN STRONG WITH GUSTY OUTFLOW WINDS...LIGHTNING AND REDUCED VISIBILITY IN HEAVY DOWNPOURS. HAVE INDICATED SHOWERS WITH ABOUT A 4 HOUR PERIOD WITH THE A MENTION OF VCTS. OUTLOOK 12Z SUNDAY THROUGH WEDNESDAY... PERIODS OF RAIN WITH MVFR CONDITIONS SUNDAY INTO TUESDAY WITH STALLED FRONT SOUTH OF THE AREA. IMPROVING WEATHER TUESDAY NIGHT INTO WEDNESDAY WITH VFR CONDITIONS EXPECTED. && .MARINE... AS OF 700 AM EDT SATURDAY...A LAKE WIND ADVISORY IS IN EFFECT. SOUTH WINDS WILL BE INCREASING TO 15 TO 25 KTS THIS MORNING...AND MAY REACH 30 KTS ON THE BROAD LAKE THIS AFTERNOON INTO THE EVENING HOURS. THIS DUE TO TIGHTENING PRESSURE GRADIENT IN ADVANCE OF APPROACHING COLD FRONT. WITH PASSAGE OF THE FRONT TONIGHT...WINDS WILL SHIFT INTO THE WEST AND DIMINISH A BIT TO 15 TO 20 KTS. WAVE HEIGHTS WILL BUILD TO 2 TO 4 FEET THIS AFTERNOON. THE THREAT OF SHOWERS AND THUNDERSTORMS WILL BE INCREASING THIS AFTERNOON AND EVENING AS WELL...WITH SHIFTING WINDS...HEAVY DOWNPOURS AND DANGEROUS LIGHTNING POSSIBLE IN ANY THUNDERSTORMS. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...TABER NEAR TERM...BANACOS/TABER SHORT TERM...TABER LONG TERM...RJS AVIATION...RJS MARINE...NEILES

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