Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 211943 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 343 PM EDT THU AUG 21 2014 .SYNOPSIS... A LOW PRESSURE AREA OVER THE GREAT LAKES WILL BRING SHOWERS AND A CHANCE OF THUNDERSTORMS OVER NORTHERN NEW YORK TODAY AND TONIGHT. THERE WILL BE A SLIGHT CHANCE FOR SHOWERS ON FRIDAY. A RIDGE OF HIGH PRESSURE WILL BUILD SOUTH FROM CANADA FRIDAY NIGHT AND WILL REMAIN OVER THE NORTH COUNTRY INTO EARLY NEXT WEEK...WITH FAIR AND DRY WEATHER EXPECTED THIS WEEKEND INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 7 AM FRIDAY MORNING/... AS OF 335 PM EDT THURSDAY...AFTN MESOANALYSIS DEPICTS A SFC LOW OVER THE NORTHERN SHORE OF LAKE ONTARIO...ASSOCIATED WITH A DEAMPLIFYING UPPER LOW OVER THE NORTHERN GREAT LAKES. BOTH OF THESE FEATURES WILL SHIFT SLOWLY EASTWARD...PASSING OVER THE NORTH COUNTRY OVERNIGHT TONIGHT. REGIONAL RADAR THIS AFTN DEPICTS SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS ST. LAWRENCE COUNTY...WITH ADDITIONAL THUNDERSTORMS IN CENTRAL NY. UNSTABLE AIRMASS WITH LAPS CAPES AROUND 2000 J/KG. EXPECT THESE TO GENERALLY PIVOT NORTHEASTWARD THROUGH EARLY EVENING WITH A CONTINUING THREAT OF LOCALLY HEAVY RAINFALL FROM ST. LAWRENCE VALLEY AND ADIRONDACKS INTO SOUTHERN VT. I`VE CONTINUED ENHANCED WORDING FOR THIS GENERAL AREA THROUGH EARLY EVENING. FORECAST QPF GENERALLY AROUND AN INCH TAPERING SHARPLY WITH NORTHEAST EXTENT. LATER TONIGHT INTO THE OVERNIGHT...RAIN COVERAGE THEN BECOMES MORE NEBULOUS/SPOTTY. DECREASING TREND TO POPS OVERNIGHT TO CHANCE ACROSS SOUTHERN VT AND SLIGHT CHANCE ELSEWHERE. OVERCAST TONIGHT WITH PATCHY AREAS OF MIST OUTSIDE OF ANY SHOWERS. FELT BOTH 12Z MAV AND MET MOS WERE BOTH TOO COLD WITH LOWS GIVEN CLOUD COVER...OPTING TO KEEP TEMPS IN THE UPPER 50S TO LOWER/MID 60S. && .SHORT TERM /7 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... AS OF 335 PM EDT THURSDAY...UPPER LOW THEN CONTINUES TO SHIFT EASTWARD INTO THE COASTAL WATERS OF NEW ENGLAND FRIDAY. NAM AND GFS DEPICT A WEAK SHORTWAVE TROUGH ROTATING AROUND AND PASSING THROUGH THE NORTH COUNTRY DURING PEAK HEATING. THEREFORE...EXPECT AN INCREASE IN DIURNAL SHOWERS FRIDAY WITH CHANCE POPS FORECAST DURING THE AFTN HOURS...TRENDING DRIER BY EVENING. MOSTLY CLOUDY/OVERCAST TRENDS TO PARTLY/MOSTLY CLOUDY BY AFTN FROM SOUTH TO NORTH WITH MORE SIGNIFICANT CLEARING EXPECTED AFTER MIDNIGHT. HIGHS FRIDAY ARE COOLEST IN SOUTHERN VT AND ESSEX COUNTY NY AND WARMEST NEAR THE CANADIAN BORDER...UPPER 60S TO MID 70S WITH LOWS IN THE UPPER 40S TO UPPER 50S. HIGH PRESSURE CONTINUES TO BUILD IN FROM THE NORTH WITH DRY WEATHER FOR SATURDAY. WHILE CLEARING SKIES AND WARMER TEMPS ARE EXPECTED FOR MOST OF THE NORTH COUNTRY...EASTERLY TRAJECTORIES AND SATURATED NAM/BTV-4 LOW-LEVEL RH PROGS SUGGEST POTENTIAL FOR MARINE LAYER/STRATUS IN EASTERN VT. WITH 850 MB TEMPS FROM +9C IN EASTERN VT TO AROUND +11C ELSEWHERE...LOOKING AT HIGHS ONLY AROUND 70 IN EASTERN VT TO MID/UPPER 70S FOR THE REST OF THE NORTH COUNTRY. GOOD RADIATIONAL COOLING SATURDAY NIGHT ALLOWS LOWS TO RANGE FROM UPPER 40S TO UPPER 50S. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 335 PM EDT THURSDAY...NO BIG CHANGES TO PREVIOUS FORECASTS FOR THE TIME. MUCH OF THE PERIOD WILL BE DOMINATED BY STRONG RIDGING ALOFT AND AT THE SURFACE (AKA: RIDGOSAUROUS). 12Z SUITE OF MODEL GUIDANCE REMAINS FAIRLY SIMILAR TO EACH OTHER AND PRIOR RUNS. NOTED THAT THE 12Z ECMWF TRENDED TOWARD THE GFS FOR THE SCENARIO ON WEDNESDAY AND IS NOW SHOWING A STRONGER RIDGE INTO MID WEEK. MODELS DIVERGE FOR THURSDAY, WITH EURO SHOWING A FASTER/MORE AMPLIFIED TROUGH BREAKING DOWN THE RIDGE. THE DIFFERENCES CONTINUE FOR BEYOND THE OFFICIAL PERIOD I`M FORECASTING FOR, BUT AN EARLY LOOK AT GUIDANCE FOR LABOR DAY WEEKEND SEEMS TO INDICATE IT WILL FEATURE SEASONABLE TEMPERATURES AND MOSTLY DRY CONDITIONS. WE`LL SEE. AS FOR THE DAILY SPECIFICS, JUST READ ON: SUNDAY...SURFACE HIGH JUST A LITTLE NORTH OF HERE SO CONTINUED LIGHT EASTERLY FLOW. 850 MPH TEMPERATURES RISE TO 11-13C (WARMEST IN WESTERN HALF), WHICH WILL SUPPORT HIGHS IN THE MID 70S EAST TO LOW 80S WEST. STRONG SUBSIDENCE WILL KEEP ANY CLOUDS TO A MINIMUM. AT NIGHT, CLEAR AND CALM SO LOOK FOR PATCHY VALLEY FOG. MONDAY...SURFACE HIGH OVERHEAD, SO HARDLY A BREEZE. 850MB TEMPERATURES UP ANOTHER DEGREE TO ABOUT 12-14C, SO ADD ABOUT 1-3F FOR THE HIGH TEMPERATURE FROM SUNDAY -- LOWER 80S PRETTY MUCH AREA WIDE. MONDAY NIGHT, MORE CLEAR/CALM/PATCHY FOG. TUESDAY...HIGH SOUTH OF HERE, SO A BIT OF A WEST/SOUTHWEST FLOW GETS ESTABLISHED. 850MB TEMPERATURES UP ANOTHER DEGREE. WITH WEST FLOW, THIS SHOULD ALSO HELP WITH SOME DOWNSLOPE INTO THE CHAMPLAIN VALLEY SO I`D EXPECT MID 80S TO BE A SOLID BET IN THE VALLEYS. THE EURO RUNS SEVERAL DEGREES COOLER, SO HAVE LEANED MORE TOWARD THE WARMER GFS TEMPERATURES. OVERNIGHT WILL FEATURE CLEAR/CALM/PATCHY FOG. WEDNESDAY...HIGH SOUTH OF HERE, SO THE AREA IS SOLIDLY IN WEST/SOUTHWEST FLOW. 850MB TEMPERATURES PUSHING 15-16C WHICH SUPPORT HIGHS IN THE MID TO UPPER 80S IN SPOTS. ADD IN SOME DOWNSLOPING OFF THE ADIRONDACKS, AND I THINK PARTS OF THE CHAMPLAIN VALLEY COULD MAKE A RUN AT 90F. I DID INCREASE TEMPERATURES SEVERAL DEGREES OVER THE BLEND OF GUIDANCE WHICH WAS BIASED A BIT COOL DUE TO THE EURO AND CLIMO IN THE MOS. THAT BLEND GAVE ME 81F FOR BTV. MEX GUIDANCE WAS 83F. I WENT 85F. WE`LL SEE HOW FUTURE GUIDANCE GOES AND IF THE TREND TO BE WARMER IS NEEDED. WEDNESDAY NIGHT AGAIN CLEAR/CALM/PATCHY FOG. THURSDAY...THIS IS WHEN IT LOOKS LIKE THE PATTERN WILL BEGIN TO BREAK DOWN. AS MENTIONED EARLIER, THE EURO IS MORE AGRESSIVE WITH A SHORTWAVE. AT THIS POINT, BEST COURSE IS TO TAKE A BLEND. HAVE PAINTED IN CHANCE LEVEL OF POPS FOR SCATTERED THUNDERSTORMS. TEMPERATURES MAY AGAIN BE VERY WARM IF THE GFS IS RIGHT. OR COOLER IF THE EURO IS RIGHT. STUCK WITH THE BLEND. WHICH STILL FEATURES LOTS OF LOWER 80S. && .AVIATION /19Z THURSDAY THROUGH TUESDAY/... THROUGH 18Z FRIDAY....CURRENTLY SHOWERS/ISOLATED T-STORMS ARE QUICKLY DEVELOPING ACROSS PORTIONS OF NORTHERN NEW YORK WHILE AN AREA OF MAINLY LIGHT RAIN (ASSOCIATED WITH MVFR CONDITIONS) IS MOVING THROUGH NORTH CENTRAL VERMONT. SOME MVFR CEILINGS TUCKED UP ALONG THE GREEN MOUNTAINS IN SOUTH-CENTRAL AS WELL. THROUGH 00Z, ANTICIPATE SHOWERS AND THUNDERSTORMS WILL CONTINUE TO BUBBLE UP MAINLY ACROSS NORTHERN NEW YORK, AFFECTING MSS, SLK AND PBG. HAVE CARRIED VCTS FOR THESE LOCATIONS, WITH SOME TEMPO GROUPS WHERE I`M A LITTLE MORE CONFIDENT ON TIMING. FOR VERMONT WENT MAINLY VCSH AS NOT ANTICIPATING AS HIGH OF A CHANCE FOR THUNDERSTORMS. FUZZY ON THE DETAILS ON WHAT COULD HAPPEN OVERNIGHT. SUSPECT THERE WILL BE A FEW SHOWERS AROUND, THOUGH CHANCES ARE BELOW 50% SO THEY WON`T SHOW IN THE TAFS. ALSO ANTICIPATE CEILINGS TO DROP INTO THE MVFR RANGE IN MANY AREAS. COULD ALSO SEE SOME LIGHT FOG REDUCING VISIBILITY TO 4-6SM. FRIDAY SHOULD BE SOMEWHAT SIMILAR TO WHAT WE ARE SEEING TODAY WITH SCATTERED SHOWERS. JUST CALLED IT `VCSH` IN THE TAFS. OUTLOOK 18Z FRIDAY THROUGH TUESDAY... VFR WITH THE FOLLOWING EXCEPTIONS -- BRIEF MVFR IN ANY SHOWERS THROUGH 06Z SATURDAY. LOCALIZED IFR IN LATE NIGHT FOG (MAINLY AN ISSUE FOR MPV AND SLK). && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...NASH NEAR TERM...LOCONTO SHORT TERM...LOCONTO LONG TERM...NASH AVIATION...NASH

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