Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 211719 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 119 PM EDT SUN SEP 21 2014 .SYNOPSIS... SHOWERS WILL DEVELOP FROM WEST TO EAST ACROSS THE NORTH COUNTRY TODAY AS LOW PRESSURE MOVING THROUGH CENTRAL QUEBEC DRAGS A COLD FRONT THROUGH THE REGION. THE FRONT CLEARS THE REGION TONIGHT WITH PRECIPITATION COMING TO AN END AFTER MIDNIGHT WITH UNSEASONABLY COOL TEMPERATURES EXPECTED FOR MONDAY. BELOW NORMAL TEMPERATURES WILL BE BRIEF HOWEVER AS WARMER AIR AND DRY CONDITIONS RETURN FOR MUCH OF NEXT WEEK UNDER A LARGE AREA OF HIGH PRESSURE. && .NEAR TERM /UNTIL 11 PM THIS EVENING/... AS OF 1023 AM EDT SUNDAY...CLOUD/POP/WEATHER FORECAST IN REALLY GOOD SHAPE WITH NO CHANGES NEED THERE ON THIS UPDATE. ONLY BLENDED TEMPERATURES INTO OBSERVED AND POPULATED THIS AFTERNOON AND MAX TEMPS WITH LAV. THIS RAISED AFTERNOON HIGHS IN THE CLEAR AREAS INTO THE MID 70S...MAINLY CENTRAL/SOUTHERN CHAMPLAIN VALLEY AND VERMONT. NEW YORK SIDE UNDER THE CLOUDS AND NEARER THE RAIN SHOULD SEE TEMPS LEVEL OFF. IN FACT MASSENA HIT 70 EARLIER AND HAS SINCED DROPPED TO 68 AT 14Z WITH LIGHT RAIN. RADAR LOOP SHOWING SWATH OF RAIN MOVING UP ST. LAWRENCE VALLEY ASSOCIATED WITH A MID LEVEL MESO-VORT CENTER. BASED ON RADAR TRENDS AND HRR MODEL REFLECTIVITY THIS AREA OF RAIN WILL PROGRESS ON NORTHEAST BUT STAY MAINLY IN NORTHERN NEW YORK. THIS AFTERNOON AS COLD FRONT PUSHES EAST RAIN AREA WILL MOVE WEST TO EAST. PRESENT POP FORECAST HAS THIS COVERED WELL WITH LIKELY POPS IN NY THROUGH 18Z THEN SPREADING IN TO VERMONT. PREVIOUS DISCUSSION...FORECAST REMAINS LARGELY ON TRACK FOR TODAY AS LOW PRESSURE MOVING THROUGH CENTRAL QUEBEC WILL DRAG A COLD FRONT ACROSS THE NORTH COUNTRY THROUGH THIS EVENING. FRONTAL BOUNDARY AND SHORTWAVE ENERGY ARE STILL FAR WEST OF THE REGION THIS MORNING...SO ONLY REAL CHANGE TO PREVIOUS FORECAST THINKING WAS TO DELAY THE ONSET OF RAIN BY A FEW HOURS. SOME UNCERTAINTY EXISTS AS TO HOW MUCH RAINFALL WE SEE AS LATEST RAP/HRRR PROGS SHOW MOISTURE THINNING AS IT APPROACHES THE REGION...BUT NAM/GFS STILL SHOW A FAIRLY SOLID LINE MOVING THROUGH. CONSENSUS IS THAT WE`LL SEE A 3-HOUR WINDOW OF SHOWERS AT ANY ONE LOCATION...WITH OVERALL QPF AMOUNTS A QUARTER TO HALF INCH BY MIDNIGHT. FRONT CLEARS THE FORECAST AREA AFTER MIDNIGHT WITH THE MID/UPPER LEVEL FLOW TURNING NORTHWESTERLY POST FRONTAL PASSAGE. THIS COMBINED WITH SOME LINGERING LOW LEVEL MOISTURE WILL SUPPORT SOME UPSLOPE SHOWERS ACROSS THE HIGHER TERRAIN...BUT FEEL THIS WILL BE SHORT- LIVED AS VERY DRY AIR FROM 500-700MB ADVECTS INTO THE REGION BY 12Z MONDAY. FOR TEMPS...WITH EARLY ARRIVAL OF PRECIP ACROSS NORTHERN NEW YORK HIGHS WILL BE THE COOLEST ACROSS THE REGION AND RUN GENERALLY IN THE UPPER 60S TO LOW 70S. MEANWHILE FROM THE CHAMPLAIN VALLEY EASTWARD WHERE WE SHOULD SEE SOME SUN THIS MORNING INTO EARLY AFTERNOON...HIGHS WILL BUMP UP INTO THE MID TO MAYBE UPPER 70S. LIKEWISE FOR TONIGHT...LOWS ACROSS NORTHERN NEW YORK WILL BE COLDEST IN THE 40S...WHILE ACROSS VT 50S. && .SHORT TERM /11 PM THIS EVENING THROUGH TUESDAY/... AS OF 405 AM EDT SUNDAY...COOLEST DAY OF THE UPCOMING WEEK COMES MONDAY WITH COLD AIR ADVECTION ACROSS THE REGION FROM THE OUTGOING LOW AND INCOMING HIGH. ANY MORNING UPSLOPE SHOWERS ACROSS THE HIGHER TERRAIN SHOULD TAPER OFF BY MID-DAY WITH MID-LEVEL DRY AIR WINNING OVER THE LOW LEVEL MOISTURE. HIGHS WILL RUN QUITE A BIT BELOW NORMAL RANGING THROUGH THE 50S...BUT WITH A MODEST NORTH WIND THROUGHOUT THE DAY IT`LL FEEL LIKE IT`S IN THE 40S AT TIMES. CLOUDS BEGIN TO CLEAR MONDAY NIGHT AS AN UPPER LEVEL RIDGE AND SURFACE HIGH PRESSURE OVER THE CENTRAL CONUS BEGIN TO SHIFT EASTWARD IN THE GREAT LAKES. THIS HIGH SHIFTS RIGHT OVERHEAD TUESDAY...WITH THE UPPER FLOW REMAINING OUT OF THE NORTHWEST SUPPORTING SOME SCATTERED DIURNAL CUMULUS FORMATION...BUT NO PRECIP IS EXPECTED. LOWS MONDAY NIGHT CONTINUE TO RUN ON THE COOL SIDE OF NORMAL IN THE UPPER 30S TO MID 40S...BUT HIGHS REBOUND ON TUESDAY PUSHING INTO THE 60S AREA-WIDE. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... AS OF 242 AM EDT SUNDAY...NO SIGNIFICANT CHANGES FROM THE PREVIOUS FORECAST. A DEEP-LAYER RIDGE WILL DEVELOP AND MOVE EASTWARD FROM THE GREAT LAKES TUESDAY NIGHT...AND REMAIN IN PLACE ACROSS THE NORTHEAST CONUS THROUGH NEXT WEEKEND. ONLY DEPARTURE FROM PREVIOUS FORECAST IS THAT THE 00Z GFS INDICATES THAT A BACKDOOR COLD FRONT MAY PUSH SOUTHWARD ACROSS NORTHERN VERMONT DURING THURSDAY NIGHT/FRIDAY MORNING. THIS IDEA HAS LESS SUPPORT FROM THE 00Z ECMWF...WHICH KEEPS A STRONGER MID-LEVEL RIDGE IN PLACE. BASED ON THE 00Z GFS...THERE MAY BE A PERIOD OF SOME CLOUDINESS WITH THE FRONT...BUT IT APPEARS OVERALL THAT PRECIPITATION IS UNLIKELY. MAINTAINED A DRY FORECAST FOR THE ENTIRE EXTENDED FCST PERIOD. TEMPERATURES WILL GENERALLY BE 6-10 DEGREES ABOVE CLIMATOLOGY FOR DAYTIME HIGHS...WITH READINGS IN THE UPPER 60S TO MID 70S FOR VALLEY LOCATIONS. LOWS WILL BE COOLEST TUESDAY NIGHT (UPR 30S TO MID 40S)...AND THEN GENERALLY IN THE MID 40S TO LOWER 50S THEREAFTER. MOSTLY CLEAR SKIES AND LIGHT WINDS MAY LEAD TO SOME NOCTURNAL FOG IN THE FAVORED RIVER VALLEYS EACH NIGHT...GENERALLY BETWEEN 04-12Z. ALL IN ALL...A DELIGHTFUL STRETCH OF WEATHER AS WE BEGIN ASTRONOMICAL FALL THIS WEEK. && .AVIATION /17Z SUNDAY THROUGH FRIDAY/... THROUGH 18Z MONDAY...VFR THIS AFTERNOON WILL TREND DOWNWARD INTO MVFR TONIGHT AND INTO MONDAY FOR MOST TAF SITES...WITH IFR LIKELY AT SLK. AREAS OF RAIN SHOWERS WILL PROGRESS ACROSS THE REGION THIS AFTERNOON AND EVENING FROM WEST TO EAST. MAY ALSO SEE AN ISOLATED THUNDERSTORM OR TWO. VISIBILITIES WILL BE PRIMARILY 6SM OR GREATER...BUT MAY SEE SOME BRIEF REDUCTIONS IN ANY HEAVIER RAIN SHOWERS. AS COLD FRONT PASSES THIS EVENING THERE WILL LIKELY BE A PERIOD WHERE CEILINGS LOWER TO MVFR FOR A TIME AS WELL. AFTER 04Z IN NORTHERN NEW YORK AND 09Z IN VERMONT WILL THEN SEE A MORE PRONOUNCED LOWERING TREND IN CEILINGS WITH MVFR DEVELOPING AT ALL TAF SITES. CEILINGS WILL BE LOWEST AT SLK WHERE IFR IS LIKELY AFTER 06Z. NOT MUCH IMPROVEMENT EXPECTED THROUGH 18Z MONDAY. MAY SEE SOME CONTINUED SCATTERED RAIN SHOWERS AS WELL AS NORTHWEST FLOW INCREASES OVERNIGHT AND INTO MONDAY MORNING. GUSTY SOUTH WINDS THIS AFTERNOON DECREASE AND TURN SOUTHWESTERLY THIS EVENING AND FIRST HALF OF TONIGHT...BEFORE INCREASING AGAIN AND GUSTING TO NEAR 20 KNOTS OUT OF THE WEST ON MONDAY. OUTLOOK 18Z MONDAY THROUGH FRIDAY... 18Z MONDAY THROUGH 00Z TUESDAY...ISOLATED TO SCATTERED RAIN SHOWERS ARE POSSIBLE OVER THE MOUNTAINS MONDAY...WITH GRADUAL IMPROVEMENT FROM MVFR CEILINGS TO VFR EXPECTED. 00Z TUESDAY ONWARD...DRY WITH BUILDING HIGH PRESSURE. GENERALLY VFR...EXCEPT LIFR/VLIFR NOCTURNAL FOG POSSIBLE SLK/MPV 06-12Z EACH MORNING TUE- FRI. && .MARINE... AS OF 405 AM SUNDAY...STRONG SOUTH WINDS WILL CONTINUE ACROSS LAKE CHAMPLAIN TODAY AS A COLD FRONT TRACKS THROUGH THE REGION THIS AFTERNOON. 20 TO 30 KNOTS THIS MORNING AHEAD OF THE FRONT WILL WEAKEN TO 15 TO 25 KNOTS THIS AFTERNOON...AND FURTHER TO 5 TO 10 KNOTS AFTER SUNSET. WAVES OF 3 TO 5 FEET THIS MORNING WILL SLOWLY SUBSIDE THIS AFTERNOON IN RESPONSE. A LAKE WIND ADVISORY REMAINS IN EFFECT THROUGH TODAY. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...LAHIFF NEAR TERM...HANSON SHORT TERM...LAHIFF LONG TERM...BANACOS AVIATION...MUCCILLI MARINE...LAHIFF

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