Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 021154 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 754 AM EDT TUE JUN 2 2015 .SYNOPSIS... IT WILL BE CLOUDY AND COOL TODAY WITH A FEW LINGERING SHOWERS AS A TROUGH OF LOW PRESSURE SLOWLY EXITS THE REGION. AFTER A FOGGY START EARLY WEDNESDAY...SKIES WILL BECOME MOSTLY SUNNY COURTESY OF HIGH PRESSURE BUILDING INTO THE REGION FROM THE NORTHWEST. DRY WEATHER IS EXPECTED WEDNESDAY AND THURSDAY...WITH MODERATING TEMPERATURES. A WEAK FRONTAL BOUNDARY WILL BRING A FEW SHOWERS FRIDAY AFTERNOON AND NIGHT. HIGH PRESSURE AND DRY WEATHER WILL RETURN FOR THE UPCOMING WEEKEND. && .NEAR TERM /UNTIL 7 PM THIS EVENING/... AS OF 711 AM EDT TUESDAY...MADE A FEW SMALL ADJUSTMENTS TO HOURLY TEMPS AND POPS FOR THIS MORNING BASED ON LATEST OBSERVATIONAL DATA AND TRENDS. TRIMMED POPS A BIT ACROSS CENTRAL PORTION OF FORECAST AREA BASED ON RADAR AND NEAR TERM GUIDANCE. BEST CHANCE FOR SHOWERS LOOKS TO BE ACROSS NORTHERN TIER OF ZONES DUE PROXIMITY SHORTWAVE TRACKING ACROSS SOUTHERN ONTARIO/QUEBEC...AND ACROSS SOUTHERN/EASTERN VERMONT EARLY TODAY. PREVIOUS DISCUSSION... LOW-LEVEL INVERTED TROUGH WILL GRADUALLY DISSIPATE ACROSS EASTERN NEW YORK TODAY. CLOSED 500MB LOW CURRENTLY OVER CENTRAL ONTARIO WILL ROTATE EASTWARD AND PASS JUST TO OUR NORTH THIS AFTERNOON. WHILE A FEW ADDITIONAL SHOWERS ARE POSSIBLE THIS MORNING...MID- LEVEL DRYING AND LOSS OF SURFACE TROUGH SHOULD ALLOW SHOWERS TO DIMINISH BY THIS AFTERNOON. WILL BE DIFFICULT TO SCOUR OUT STRATUS LAYER...SO ANTICIPATE CLOUDY SKIES WITH JUST A FEW AFTERNOON BREAKS IN THE OVERCAST. CLOUDS AND LIGHT NORTH WINDS WILL LIMIT DAYTIME HEATING ONCE AGAIN...YIELDING HIGH TEMPERATURES GENERALLY IN THE 55-60F RANGE. FOR POPS...INDICATED 40-50 PERCENT CHANCE IN THE MORNING...GRADUALLY DECREASING TO SLIGHT CHANCE THIS AFTERNOON...TAPERING OFF FROM WEST TO EAST. && .SHORT TERM /7 PM THIS EVENING THROUGH THURSDAY/... AS OF 356 AM EDT TUESDAY...EXPECT CLEARING SKIES TONIGHT AS CLOSED UPPER LEVEL LOW SHIFTS EASTWARD INTO THE CANADIAN MARITIMES AND SURFACE RIDGE GRADUALLY BUILDS INTO THE REGION FROM SOUTHEASTERN ONTARIO AND QUEBEC. THE COMBINATION OF DIMINISHING WIND...CLEARING SKIES...AND THE RECENT RAINFALL WILL LIKELY LEAD TO WIDESPREAD FOG FORMATION...WHICH COULD BE DENSE IN SPOTS BETWEEN 06-12Z WEDNESDAY. LOW TEMPERATURES ARE GENERALLY EXPECTED TO BE IN THE LOW TO MID 40S...BUT A FEW SPOTS IN FAR NORTHEASTERN VERMONT AND WITHIN THE NORTHERN ADIRONDACK REGION COULD FALL INTO THE MID TO UPPER 30S. THE FOG SHOULD PREVENT TEMPS FALLING ANY LOWER...THUS MITIGATING THE FROST THREAT. EXPECT FOG AND LINGERING STRATUS TO ERODE WEDNESDAY MORNING AS BOUNDARY LAYER MIXES OUT. HIGH PRESSURE CRESTING OVER NEW ENGLAND DURING THE DAY WILL ALLOW FOR SKIES TO BECOME MOSTLY SUNNY BY AFTERNOON ALONG WITH LIGHT WINDS. 850MB TEMPS RANGING FROM +6 TO +9C SUPPORT HIGHS IN THE UPPER 60S TO LOWER 70S. HIGH PRESSURE REMAINS OVER THE AREA WEDNESDAY NIGHT. CLEAR SKIES AND LIGHT WINDS WILL ALLOW FOR GOOD RADIATIONAL COOLING. MAY SEE SOME FOG ONCE AGAIN...BUT SEEING THAT WE WILL BE A FULL DAY REMOVED FROM ANY PRECIPITATION...EXPECT IT TO BE CONFINED TO THE MORE CLIMO FAVORED RIVER VALLEYS. LOW TEMPS WILL BE MAINLY IN THE 40S. CONTINUED DRY WEATHER ON THURSDAY AS HIGH PRESSURE SLIDES EAST INTO THE ATLANTIC. LIGHT RETURN SOUTHERLY FLOW DEVELOPS...WHICH WILL ALLOW FOR WARMER TEMPERATURES...BUT ALSO FOR SOME MOISTURE TO CREEP NORTH FROM THE MID ATLANTIC STATES. THE RESULT WILL BE SOME INCREASE IN CLOUDS OVER SOUTHERN SECTIONS DURING THE AFTERNOON HOURS...BUT REMAINING SUNNY NORTH. 850 MB TEMPS CLIMB TO 10-11C WHICH WILL ALLOW FOR HIGHS IN THE 70S. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... AS OF 323 AM EDT TUESDAY...HIGH PRESSURE SHOULD KEEP MOST OF THURSDAY EVENING AND FRIDAY MORNING DRY BEFORE AN UPPER LEVEL LOW AND ASSOCIATED COLD FRONT DROP SOUTH FROM CANADA BRINGING A CHANCE FOR SHOWERS AND THUNDERSTORMS ON FRIDAY NIGHT INTO SATURDAY MORNING. THE MODELS IN THE 00Z RUN CAME IN WITH A BIT MORE INCONSISTENCY WITH REGARDS FOR TIMING THAN I WOULD LIKE AT THIS POINT. THE GENERAL CONSENSUS IS THAT THE MODELS ARE STRUGGLING WITH HOW THE SOUTHERN SURGE OF WARM AIR ADVECTION AND MID LEVEL MOISTURE WILL MERGE WITH THE NORTHERN STREAM SYSTEM. BOTH THE CANADIAN AND ECMWF SHOW A FAIRLY WELL DEFINED FRONTAL SYSTEM MOVING ENTERING THE SAINT LAWRENCE VALLEY AND THEN PROPAGATING ACROSS THE REGION BEFORE FALLING APART BY 12Z SATURDAY MORNING. THE 00Z GFS WHICH HAD PREVIOUSLY SHOWN SOMETHING SIMILAR IS NOW SIGNIFICANTLY MORE PROGRESSIVE BRINGING THE FRONT THROUGH ABOUT 6-12 HOURS FASTER. THIS LEADS TO A CHALLENGING TEMPERATURE FORECAST FOR SATURDAY AS DEPENDING ON HOW FAR THE FRONT MAKES IT THROUGH THE AREA THE TEMPS WILL VARY WIDELY. THE FORECAST AS IT STANDS RIGHT NOW IS FOR TEMPS IN THE MID TO UPPER 60S ON SATURDAY UNDER THE MODERATE TO STRONG NORTHERLY COLD AIR ADVECTION BEHIND THE FRONT. CONCERNING THE SHOWERS AND POTENTIAL THUNDERSTORMS, THE MODELS ARE IN DECENT AGREEMENT WITH SOME WEAK TO MODERATE INSTABILITY MAINLY ALONG THE CONVERGENT ZONE WHERE THE FRONT MEETS UP WITH THE SOUTHERN STREAM OF ENERGY. WITH 30-40KTS OF 0-6KM SHEAR AND THE AFOREMENTIONED INSTABILITY A FEW THUNDERSTORMS WILL BE POSSIBLE SO I`VE GONE AHEAD AND ADDED WORDING OF THUNDER TO THE FORECAST. AS OF RIGHT NOW THE WEAK INSTABILITY WILL HOLD BACK THE DEVELOPMENT OF STRONG THUNDERSTORMS BUT THAT WILL BE SUBJECT TO FUTURE MODEL RUNS. BEHIND THE FRONT DRY AIR WILL MOVE IN WITH A BROAD DOME OF HIGH PRESSURE QUICKLY MOVING ACROSS THE REGION AS A 50-60KT 500MB JET STEERS THE HIGH TO THE EAST. THAT DRY AIR WILL BE SHORT LIVED HOWEVER AS THE MODELS ARE IN DECENT AGREEMENT THAT THERE WILL BE A SECOND LOW PRESSURE SYSTEM THAT WILL PASS THROUGH THE REGION EARLY NEXT WEEK. THERE ISN`T MUCH CONSENSUS ON TIMING OR INTENSITY SO FOR THE TIME BEING I`LL CONTINUE THE PREVIOUS FORECAST OF 40-50% CHANGE FOR SHOWERS FROM MONDAY MORNING THROUGH TUESDAY MORNING. WILL REFINE THAT WINDOW AS THE MODELS COME INTO MORE AGREEMENT IN FUTURE RUNS. TEMPS THROUGH THE EXTENDED WITH START OFF RIGHT AROUND CLIMO WITH MAX TEMPS ON FRIDAY IN THE MID TO LOW 70S AND OVERNIGHT LOWS IN THE MID TO LOW 50S. THEN AS THE FRONT COMES THROUGH TEMPS WILL DROP SOME 5-10 DEGREES ACROSS THE REGION WITH MAX TEMPS ONLY IN THE MID TO UPPER 60S SATURDAY AND LOWS OVERNIGHT IN THE UPPER 40S. WE WILL THEN REBOUND BACK TOWARDS CLIMO WITH HIGHS IN MID 70S AND LOWS IN THE MID 50S EARLY NEXT WEEK. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... THROUGH 12Z WEDNESDAY... WE SHOULD SEE MARGINALLY IMPROVING CONDITIONS THROUGH THE FORECAST PERIOD FROM THE SCATTERED IFR AND MVFR ACROSS THE TAFS SITES TO MVFR/VFR BY MID MORNING AND ALL VFR BY LATE AFTERNOON. HOWEVER THAT WILL BE SHORTLY LIVED AS TONIGHT WE WILL MOST LIKELY HAVE TO DEAL WITH LOW STRATUS VS FOG AS THE BOUNDARY LAYER WINDS GO MOSTLY CALM. ACROSS NORTHERN NEW YORK RIGHT NOW BOTH SLK AND MSS ARE REPORTING IFR CEILINGS WITH MVFR VISIBILITIES AND UNDER THE LIGHT NORTHEASTERLY WINDS EXPECT THAT TO CONTINUE THROUGH THE MID MORNING BEFORE DAYTIME HEATING AND MIXING CAN ERODE THE LOW CEILINGS. SIMILARLY IN BTV EXPECT THE IFR CONDITIONS TO BEGIN TO ERODE AND IMPROVE TOWARDS MVFR BY 14Z AND FINALLY HAVE THE CEILINGS LIFT TO VFR BY 20-23Z. OVERNIGHT THE WINDS WILL BECOME LIGHT AND VARIABLE HOWEVER SOME OF THE MODEL GUIDANCE IS NOW HINTING AT THE BOUNDARY LAYER WINDS STAYING HIGH ENOUGH THAT THE THREAT WILL BE VERY LOW STRATUS INSTEAD OF DENSE FOG. AS OF THIS FORECAST UPDATE I`VE LEFT THE FOG IN AS WE SHOULD SEE LIGHT ENOUGH WINDS TO DEVELOP RADIATIONAL FOG AT LEAST IN MPV AND SLK. WINDS WILL REMAIN NORTHEASTERLY LIGHT TO MODERATE LESS THAN 10KTS DURING THE FORECAST PERIOD. OUTLOOK 12Z WEDNESDAY THROUGH SATURDAY... 12Z WEDNESDAY THROUGH 12Z FRIDAY...MAINLY VFR WITH BUILDING HIGH PRESSURE. EXCEPTION WILL BE POTENTIAL FOR AREAS OF DENSE FOG AT ALL TERMINALS IN THE 02-13Z WEDNESDAY TIME FRAME. 12Z FRIDAY ONWARD...INCREASING CHANCE FOR SHOWERS WITH VFR/MVFR CONDITIONS AS A FRONTAL PASSAGE MOVES INTO THE AREA SATURDAY AFTERNOON. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...RJS NEAR TERM...RJS SHORT TERM...RJS LONG TERM...DEAL AVIATION...DEAL

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