Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 201422 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 1022 AM EDT WED AUG 20 2014 .SYNOPSIS... A RIDGE OF HIGH PRESSURE WILL MOVE EAST OF THE REGION THIS AFTERNOON. A LOW PRESSURE AREA OVER THE WESTERN GREAT LAKES WILL BRING INCREASING CLOUDS TO THE NORTH COUNTRY TODAY...WITH A CHANCE OF SHOWERS AND A POSSIBLE THUNDERSTORM ACROSS NORTHERN NEW YORK LATE THIS AFTERNOON. SKIES WILL BECOME CLOUDY ACROSS NORTH COUNTRY TONIGHT WITH THE BEST CHANCE FOR SHOWERS AND POSSIBLE THUNDERSTORMS ACROSS NORTHERN NEW YORK. SHOWERS WILL OVERSPREAD THE REMAINDER OF THE REGION ON THURSDAY...WITH A CHANCE OF THUNDERSTORMS ACROSS NORTHERN NEW YORK ON THURSDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 1022 AM EDT WEDNESDAY...RADIATIONAL FOG IN THE EASTERN VT RIVER VALLEYS HAS BURNED OFF. REGIONAL RADAR CONTINUES TO SHOW A SLOW NORTHEASTWARD MOTION TO SHOWERS AND EMBEDDED THUNDERSTORMS IN WESTERN NY/PA. EARLY MORNING HI-RES REFLECTIVITY GUIDANCE HAS STRUGGLED WITH ITS TIMING...THOUGH MORE RECENT RUNS POINT TO AREA OF SHOWERS/STORMS NOT MAKING IT INTO THE ST. LAWRENCE VALLEY UNTIL LATER THIS AFTERNOON...AND NOT UNTIL AFTER 00Z FOR THE CHAMPLAIN VALLEY AREA. ADJUSTED POPS TO MATCH THESE GENERAL TRENDS. STILL THINK THREAT OF THUNDER WILL EXIST ESPECIALLY WITH A LATER TIMING ALLOWING FOR A LITTLE BETTER INSTABILITY (GENERALLY AOB 1000 J/KG). IT ALSO IS A FAIRLY MOISTURE-LADEN AIRMASS WITH PWS PER BUF/ALB RAOBS BETWEEN 1.2-1.5"...THOUGH NOT EXCESSIVELY SO. SO COULD BE A FEW DOWNPOURS IN STEADIER RAIN SHOWERS ACROSS NORTHERN NEW YORK. I DID ADJUST HIGHS UP A COUPLE DEGREES ACROSS VERMONT AS SKIES REMAIN MOSTLY CLEAR...AND LOWERED A BIT ACROSS NORTHERN ST. LAWRENCE VALLEY AREA. WITH SFC WARM FRONT ANCHORED ALONG THE NORTHERN ST. LAWRENCE VALLEY...SLIGHTLY COOLER/DRIER AIR NEAR THE MOUTH OF THE ST. LAWRENCE RIVER MAY FILTER DOWN ON NORTHEAST SFC FLOW. HIGHS IN THE 70S FOR NORTHERN NEW YORK...AND UPPER 70S TO LOWER/MID 80S IN THE CHAMPLAIN VALLEY. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/... AS OF 450 AM EDT WEDNESDAY...MODELS IN SOMEWHAT BETTER AGREEMENT TONIGHT IN BRINGING SHOWERS AND POSSIBLE THUNDERSTORMS INTO NORTHERN NEW YORK TONIGHT. MOS POPS LOOK TOO HIGH ACROSS VERMONT TONIGHT...SO HAVE GONE BELOW MOS GUIDANCE FROM THE CHAMPLAIN VALLEY EASTWARD. THUS...HAVE A SHARP POP GRADIENT FROM THE CONNECTICUT VALLEY TO THE SAINT LAWRENCE VALLEY TONIGHT. THE LOWEST POPS OVER EASTERN VERMONT WITH THE HIGHEST POPS ACROSS THE ADIRONDACKS AND SAINT LAWRENCE VALLEY IN NORTHERN NEW YORK. MODELS IN BETTER AGREEMENT IN BRINGING SHOWERS INTO VERMONT ON THURSDAY. THUS...HAVE INCREASED POPS ACROSS VERMONT ON THURSDAY. HAVE KEPT IN A CHANCE OF THUNDERSTORMS ACROSS NORTHERN NEW YORK ON THURSDAY...AS THIS IS WHERE THE BEST INSTABILITY WILL BE. ON FRIDAY...UPPER LOW SLIDES SOUTH OF THE REGION WITH AN UPPER RIDGE BUILDING SOUTH FROM QUEBEC. THUS...DECREASING CHANCE FOR SHOWERS ON FRIDAY. HAVE JUST GONE WITH SLIGHT CHANCE POPS ON FRIDAY. THE UPPER RIDGE BUILDING SOUTH FROM CANADA ON FRIDAY MARKS THE START OF A REX BLOCK DEVELOPING ACROSS THE REGION FOR THIS WEEKEND. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... AS OF 400 AM EDT WEDNESDAY...LARGE SCALE PATTERN WL FEATURE A BLOCKING TYPE SCENARIO DEVELOPING ACRS THE EASTERN CONUS. BOTH ECMWF/GFS SHOWS A DEVELOPING CLOSED 5H CYCLONIC CIRCULATION OVER THE WESTERN ATLANTIC AND BUILDING HGHT RIDGE ACRS THE CENTRAL CONUS INTO THE GREAT LAKES BY SUNDAY. THIS PATTERN WL RESULT IN MAINLY DRY CONDITIONS FOR DAYS 4 THRU 7 WITH NEAR TO SLIGHTLY ABOVE NORMAL TEMPS. SFC HIGH PRES BUILDING DOWN FROM EASTERN CANADA WL PUSH SLIGHTLY COOLER TEMPS INTO OUR CENTRAL/EASTERN CWA OVER THE WEEKEND...ASSOCIATED WITH EASTERLY FLOW AND 85H TEMPS BTWN 8-10C. THESE TEMPS SUPPORT HIGHS MAINLY IN THE 70S ACRS OUR REGION WITH THIS COOLER MARITIME AIR WL HAVE THE GREATEST IMPACTS ON EASTERN VT...ASSOCIATED WITH LLVL EASTERLY FLW. SFC HIGH PRES REMAINS NEARLY STATIONARY INTO NEXT WEEK...WITH BUILDING HGHTS ALOFT. THIS WL SLOWLY ALLOW TEMPS TO CLIMB...WITH BEST THERMAL RIDGE AND WARMEST LLVL TEMPS ACRS THE CENTRAL PLAINS INTO THE OHIO VALLEY. THIS VERY WARM AIR MASS...HAS DIFFICULTIES ADVECTING INTO OUR CWA...GIVEN PLACEMENT OF SFC RIDGE AND NW FLW ALOFT...BUT SHOULD BY THE MID TO END OF NEXT WEEK. PROGGED 85H TEMPS WL WARM BTWN 12-14C BY NEXT WEDS...WITH HIGHS IN THE M/U 70S MTNS/NEK TO L80S WARMER VALLEYS. WL CONT TO KEEP FCST DRY AS BEST ULVL SUPPORT AND MID LVL MOISTURE IS LOCATED TO OUR WEST THRU THE MIDDLE OF NEXT WEEK. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/... THROUGH 12Z THURSDAY....LIFR IN FOG WL PREVAIL AT MPV UNTIL 13Z...BEFORE GRADUALLY DISSIPATING. MID/UPPER LVL CLOUDS WL SPREAD FROM WEST TO EAST ACRS OUR TAF SITES THIS MORNING AHEAD OF AN APPROACHING WARM FRNT. THESE CLOUDS WL PRODUCE SCATTERED SHOWERS ACRS NORTHERN NEW YORK TAF SITES BY 21Z TODAY...AND SPREAD INTO VT BY THIS EVENING. INITIALLY GIVEN THE VERY DRY LLVLS...EXPECTING SOME OF THE MOISTURE TO FALL AS VIRGA. SOME MVFR CIGS COULD DEVELOP AT SLK BY THIS EVENING...AS MOISTURE INCREASES ON SOUTHERLY WINDS. OTHERWISE...LOOK FOR LIGHT TRRN DRIVEN WINDS THIS MORNING...TO BECOME SOUTH/SOUTHEAST AT 4 TO 8 KNOTS TODAY...WITH EASTERLY FLW AT MSS. OUTLOOK 12Z THURSDAY THROUGH SUNDAY... ADDITIONAL SHOWERS ARE LIKELY INTO THURSDAY WITH PERIODS OF MVFR CIGS/VIS...ESPECIALLY AT SLK/MPV. FOG/BR WL BE LIMITED BY THE INCREASING CLOUDS AND THREAT FOR SHOWERS. SFC HIGH PRES ACRS NORTHERN MAINE WL BUILD INTO OUR TAF SITES ON SATURDAY INTO SUNDAY WITH VFR CONDITIONS LIKELY. THE COMBINATION OF CLR SKIES AND LIGHT WINDS WL RESULT IN FOG/BR AT SLK/MPV BOTH SAT AND SUN MORNINGS WITH IFR CONDITIONS LIKELY. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...WGH NEAR TERM...WGH/LOCONTO SHORT TERM...WGH LONG TERM...TABER AVIATION...TABER

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