Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 292357 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 757 PM EDT WED JUL 29 2015 .SYNOPSIS... AFTER ANOTHER VERY WARM DAY ACROSS THE NORTH COUNTRY...TEMPERATURES WILL REMAIN MILD TONIGHT WITH LOWS FROM THE 60S TO LOWER 70S. A FEW THUNDERSTORMS WILL BE POSSIBLE OVER THE HIGHER TERRAIN THIS AFTERNOON AND EVENING...BUT MORE WIDESPREAD THUNDERSTORMS ARE EXPECTED ON THURSDAY AS A COLD FRONT MOVES ACROSS THE REGION. THESE THUNDERSTORMS WILL HAVE THE POTENTIAL TO BECOME STRONG TO SEVERE WITH GUSTY WINDS...HAIL...AND HEAVY DOWNPOURS. COOLER WEATHER RETURNS ON FRIDAY AS THE COLD FRONT EXITS THE AREA THURSDAY NIGHT. && .NEAR TERM /UNTIL 8 AM THURSDAY MORNING/... AS OF 752 PM EDT WEDNESDAY...ISOLATED THUNDERSTORMS ACROSS THE CHAMPLAIN VALLEY AND ACROSS NRN LAMOILLE COUNTY DURING THE LATE AFTN/EARLY EVENING - DRIVEN BY VERY WARM PBL TEMPERATURES AND ORORGAPHIC FORCING - HAVE LARGELY DISSIPATED AS OF 2345Z. WITH SHORTWAVE RIDGING IN PLACE THROUGH THE OVERNIGHT PERIOD...LOOKING FOR MOSTLY CLEAR CONDITIONS AFTER SUNSET. WILL SEE SCATTERED MID- UPR LEVEL CLOUDS FROM THE WEST TOWARDS DAYBREAK ASSOCIATED WITH UPSTREAM FRONTAL SYSTEM. OTHERWISE...WITH SOUTHERLY LOW-LEVEL FLOW GRADUALLY INCREASING AND 925 MB TEMPERATURES HOLDING IN THE 22-24C RANGE...TEMPERATURES WILL BE QUITE MILD...WITH LOWS FOR MUCH OF THE AREA IN THE 60S AND LOWER 70S. SOME PATCHY FOG POSSIBLE ACROSS THE VALLEYS OF EASTERN VERMONT...BUT COVERAGE IS EXPECTED TO BE LESS THAN PREVIOUS NIGHTS DUE TO INCREASED WIND FIELD. NOTING 20-25 KTS AT SLK AROUND 900MB LEVEL BY 06Z...SO SHOULD BE JUST ENOUGH TURBULENT MIXING TO MITIGATE NOCTURNAL FOG POTENTIAL IN THE VALLEYS WITHIN THE NRN ADIRONDACK REGION. && .SHORT TERM /8 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... AS OF 244 PM EDT WEDNESDAY...INITIAL FRONT/DEW POINT BOUNDARY WILL CROSS THE REGION FROM WEST TO EAST DURING THE DAY THURSDAY BRINGING A QUICK PERIOD OF SHOWERS/THUNDERSTORMS. CURRENT TIMING LOOKS TO BE 12-16Z ACROSS THE ADIRONDACKS/SAINT LAWRENCE VALLEY OF NEW YORK...16-19Z IN THE CHAMPLAIN VALLEY...AND 18-22Z ACROSS CENTRAL AND EASTERN VERMONT. GREATEST THREAT FOR ANY SEVERE WEATHER WILL BE FROM THE CHAMPLAIN VALLEY EASTWARD INTO VERMONT...AND ESPECIALLY POINTS SOUTH AND EAST OF THERE. FOR MUCH OF NORTHERN NEW YORK...FRONTAL PASSAGE WILL LIKELY BE TOO EARLY FOR SEVERE. CURRENT MODELS INDICATING ROUGHLY 500-1500 J/KG OF MLCAPE DEVELOPING BY 18Z FROM THE CHAMPLAIN EASTWARD...WITH 0-6KM SHEAR OF ABOUT 30-40 KNOTS. WHILE A WIDESPREAD SEVERE EVENT IS NOT ANTICIPATED...THIS SHOULD BE ENOUGH FOR SOME THUNDERSTORM ORGANIZATION WITH A SCATTERED SEVERE THREAT. WIND SHEAR IS MOSTLY UNI-DIRECTIONAL FROM THE SOUTHWEST AND PARALLEL TO THE FRONT...SO PRIMARY CONCERN WILL BE DAMAGING WINDS FROM BOWING SEGMENTS. WITH THE EARLY ONSET OF CONVECTION...AN OFFICIAL HEAT WAVE IS NOT FORECAST AT BTV...WITH HIGHS FOR MUCH OF THE REGION IN THE 80S. PARTS OF SOUTHEAST VERMONT MAY BE ABLE TO SQUEEZE OUT ANOTHER 90 DEGREE DAY. SOUTHWEST FLOW CONTINUES ACROSS THE REGION THURSDAY NIGHT AS THE UPPER TROUGH LAGS BEHIND AND EVENTUALLY CROSSES EARLY FRIDAY MORNING. THUS THE COOLER AIR WILL TAKE ITS TIME MOVING IN...AND WE SHOULD BE LOOKING AT LOWS IN THE 60S FOR MOST...EXCEPT SOME 50S IN THE NORMALLY COOLER SPOTS OF THE ADIRONDACKS AND NORTHEAST KINGDOM. BY FRIDAY...WESTERLY FLOW TAKES HOLD WITH MOSTLY SUNNY SKIES...HOWEVER THE NEXT VORT IN CYCLONIC FLOW WILL ALREADY BE APPROACHING NORTHERN NEW YORK BY EVENING AS A LARGE CLOSED LOW TAKES HOLD ACROSS HUDSON BAY. THIS WILL BRING WITH IT ANOTHER CHANCE FOR SHOWERS/THUNDERSTORMS ACROSS NORTHERN NEW YORK...MAINLY THE SAINT LAWRENCE VALLEY. WIND FIELD WILL ACTUALLY STILL BE QUITE STRONG...SO A GUSTY THUNDERSTORM IS POSSIBLE. HIGH TEMPERATURES WILL BE COOLER...CLOSER TO THE CLIMATOLOGICAL NORMALS...MAINLY 75-85F. THE CHANCES FOR A FEW SHOWERS LINGER INTO FRIDAY NIGHT ACROSS THE NORTH COUNTRY. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 259 PM EDT WEDNESDAY...CYCLONIC NW FLOW ACROSS EASTERN NOAM WILL INFLUENCE OUR WEATHER THROUGH THE PERIOD. IN THIS PATTERN TEMPERATURES WILL LARGELY BE SEASONABLE WITH NO EXPECTED HEAT. MID-LEVEL DISTURBANCE ROTATING IN THE BASE OF EASTERN NOAM TROUGH WILL BRING ABT CHC/SCT -SHRA/-TSRA FRI NGT THRU SAT. WE/RE STILL IN FLOW BUT MORE STABLE AND WEAKER ENERGY THUS CHANCES STILL THERE SUN BUT LESS SO. ANOTHER SHARPER SHORTWAVE AND SURFACE COLD FRONT APPROACH MON NGT/TUE WITH A BETTER CHANCE OF SHRA/TSRA THEN SLIGHT HEIGHT BUILDING AS TROUGH AXIS SHIFTS NE SHOULD BRING ABOUT DRIER CONDITIONS MID WEEK. AGAIN...TEMPERATURES WILL LARGELY BE SEASONABLE THROUGH THIS PERIOD. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... THROUGH 00Z THURSDAY...VFR CONDITIONS WILL PREVAIL THROUGH THE OVERNIGHT HOURS WITH SCT-BKN MID/HIGH CLOUDS DRIFTING THROUGH THE REGION BEFORE A FRONTAL SYSTEM BRINGS A LINE OF SHOWERS THROUGH IMPACTING ALL TAF SITES. EXPECT AS THE SHOWERS MOVE THROUGH THE AREA MOST SITES WILL SEE PERIODS OF IFR/MVFR VSBY/CIGS. SOUTHWEST (EXCEPT SOUTHEAST AT PBG/RUT) AT 5 TO 10 KNOTS WILL CONTINUE THIS EVENING BEFORE DECOUPLING OVERNIGHT AT MPV. GIVEN THE CALM BOUNDARY LAYER WINDS ANTICIPATE THAT IFR FOG WILL DEVELOP AND PREVAIL FOR THE EARLY MORNING AT MPV. AT SLK EXPECT THE ADVANCING TROUGH WILL INCREASE THE BOUNDARY LAYER WINDS ENOUGH THAT THERE WILL BE SUFFICIENT MIXING TO AVOID ANY PROLONGED FOG. TIMING FOR THE SHOWERS AND POTENTIAL THUNDERSTORMS WILL SEE THE LINE ENTERING THE SAINT LAWRENCE VALLEY BY 12Z PROGRESSING TO THE CHAMPLAIN VALLEY BY 16Z AND THEN CLEARING THE AREA BY 21Z TOMORROW. OUTLOOK 00Z THURSDAY THROUGH SUNDAY... 18Z THU - 00Z FRI: VFR WITH BRIEF MVFR/IFR IN SHOWERS/STORMS. ISOLATED SEVERE TURBULENCE/WINDS/HAIL POSSIBLE. 00Z FRI - 12Z SAT: MAINLY VFR. CHANCE MVFR/IFR FOG MAINLY AT MPV/SLK. 12Z SAT - 00Z MON: MAINLY VFR. CHANCE SHRA/TSRA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...MUCCILLI NEAR TERM...BANACOS SHORT TERM...MUCCILLI LONG TERM...SLW AVIATION...DEAL/SLW

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