Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 041756 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 156 PM EDT MON MAY 4 2015 .SYNOPSIS... AN UPPER RIDGE WILL PUSH OFFSHORE AS A WEAK COLD DROPS SOUTH FROM QUEBEC ACROSS THE NORTH COUNTRY. AHEAD OF THE FRONT THERE WILL BE GUSTY SOUTHWEST WINDS THAT WILL COMBINE WITH VERY DRY CONDITIONS TO PRODUCE NEAR CRITICAL FIRE WEATHER CONDITIONS IN LOCATIONS BELOW 2000 FEET. SCATTERED SHOWERS WILL ACCOMPANY THE FRONT ON MONDAY NIGHT WITH COOLER AIR ARRIVING ON TUESDAY RETURNING THE REGION TO NEAR SEASONAL TEMPERATURES AND DRY WEATHER THROUGH THE REST OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 103 PM EDT MONDAY...VERY MINOR UPDATE TO INCREASE TEMPS ACROSS PARTS OF THE CHAMPLAIN AND SAINT LAWRENCE VALLEYS BY SEVERAL DEGREES. BASED ON GOOD MIXING AND VERY DRY SFC CONDITIONS...EXPECTING HIGHS IN THE LOW/MID 80S CPV/SLV WITH M/U 70S IN THE MTN TOWNS...INCLUDING THE NEK. WINDS HAVE GUSTED TO 39 MPH AT KMSS THIS AFTN...BUT MUCH LESS OVER THE CPV AND MOST OF VT...WITH GUSTS IN THE 15 TO 20 MPH RANGE. THESE WINDS WILL INCREASE AS SFC HEATING CONTS OVER MOST OF THE REGION THIS AFTN...WITH RH VALUES DROPPING INTO THE 20% RANGE...BEFORE INCREASING AS SFC FRONT APPROACHES LATE TODAY. ALREADY SEEING SOME WEAK RADAR RETURNS ASSOCIATED WITH FRONT ACROSS THE OTTAWA VALLEY...BUT GIVEN DRY LOW LEVELS...NOT EXPECTING ANY PRECIP TO REACH THE GROUND THROUGH THIS AFTN. HAVE UPDATED FCST TO INCLUDE A USER REQUESTED RED FLAG WARNING FOR ENTIRE CWA FROM 11 AM TO 7 PM THIS EVENING...GIVEN THE EXTREMELY DRY FINE FUELS. THE SLOWER TIMING OF SURFACE BOUNDARY WILL ALLOW MIN RH`S TO DROP BTWN 20 AND 30% MOST LOCATIONS THIS AFTN...BUT WINDS WILL BE MARGINAL...ESPECIALLY ACROSS THE PROTECTED VALLEYS OF CENTRAL/EASTERN AND SOUTHERN VT. EXPECTING STRONGEST WINDS WITH GUSTS BTWN 25 AND 30 MPH ACROSS THE SAINT LAWRENCE VALLEY AND NORTHERN DACKS. A FEW LOCALIZED GUSTS TO 40 MPH WILL BE POSSIBLE IN THE SAINT LAWRENCE VALLEY WHERE ALIGNED FLOW WILL ENHANCE THE WIND SPEEDS. OTHERWISE...TEMPS WILL WARM INTO THE MID 70S MTNS TO LOWER 80S WITH INCREASING CLOUDS FROM APPROACHING SFC BOUNDARY THIS AFTN. ANY PRECIP WILL ARRIVE TWD SUNSET ACROSS THE SAINT LAWRENCE VALLEY AND SPREAD INTO VT OVERNIGHT...WITH AMOUNTS GENERALLY < 0.25" AND CONFINED TO THE MOUNTAINS. PREVIOUS FCST BELOW... THE LACK OF CLOUD COVER HAS ALLOW FOR TEMPS TO QUICKLY BEGIN HEATING UP THIS MORNING AFTER DAY BREAK. TEMPS OVER NORTHERN NEW YORK IN THE SAINT LAWRENCE VALLEY ARE ALREADY IN THE LOW 60S WITH MID 50S ELSEWHERE AND EXPECT TO CONTINUE WARMING THROUGH THE DAY MOST LIKELY REACHING THE 80S FOR A DAYTIME MAX TEMP BEFORE THE FRONT THIS EVENING. LIGHT WINDS ARE CURRENTLY SOUTHWEST 4-8 KTS ACROSS THE REGION. UNDER CLEAR SKIES. EXCEPT FOR THE POTENTIALLY DANGEROUS FIRE WEATHER CONDITIONS... TODAY THROUGH THE AFTERNOON IS SHAPING UP TO BE A LOVELY DAY AND POTENTIALLY THE FIRST DAY IN THE 80S IN BURLINGTON SINCE 10/15/2014. THE FORECAST IS IN PRETTY GOOD SHAPE SO OTHER THAN A QUICK UPDATE TO FRESHEN UP THE TEMPS IN THE FIRST 3-4 HOURS NO CHANGES NECESSARY. PREVIOUS DISCUSSION AS OF 355 AM MONDAY...WE WILL DRY OUT TODAY BECAUSE OF THE UPPER LEVEL RIDGE THAT HAS BEEN IN PLACE FOR THE PREVIOUS COUPLE OF DAYS AND THE SOUTHERLY WINDS AT THE SURFACE. THIS WILL WARM THE AREA VERY QUICKLY DURING THE DAY TODAY. LOW AND MID LEVEL MOISTURE IS QUITE LOW ACROSS THE NORTH COUNTRY AND THUS OVERALL CLOUD COVER WILL BE MINIMAL. EXPECT MOSTLY CLEAR SKIES THROUGH THIS AFTERNOON BEFORE A COLD FRONT BEGINS TO MOVE SOUTH INTO THE REGION. CLOUDS WILL OVERSPREAD FROM NORTHWEST TO SOUTHEAST AHEAD OF THE FRONT AND THE ATMOSPHERE WILL BECOME VERY WELL MIXED UP TO 7000 FEET ACROSS THE NORTH COUNTRY. THE WELL MIXED ATMOSPHERE AND STEEP LOW LEVEL LAPSE RATE WILL BRING GUSTY WINDS AHEAD OF THE FRONT GUSTING 20-30KTS ACROSS MUCH OF NORTHERN NEW YORK AND 15-20KTS ACROSS VERMONT. THE DRY AIR AND GOOD MIXING WILL ALLOW FOR TEMPERATURES ACROSS THE REGION TO WARM INTO AT LEAST THE UPPER 70S FOR THE SECOND DAY IN A ROW WITH 80F BEING A REAL POSSIBILITY IN THE SAINT LAWRENCE AND CHAMPLAIN VALLEYS. WITH LAKE CHAMPLAIN STILL BEING QUITE COLD THE AIR TEMP OVER THE LAKE WILL BE SIGNIFICANTLY COOLER AND SO ACROSS THE BROAD LAKE I`VE ONLY GOT MAX TEMPS TODAY WARMING TO AROUND 70 AND THE NEAR SHORE AREAS IN THE LOW TO MID 70S. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... AS OF 355 AM EDT MONDAY... BY 23Z THIS EVENING OR 7PM, EXPECT THE FIRST SHOWERS TO START TO MOVE INTO NORTHERN NEW YORK AS THE COLD FRONT DRAWS CLOSER TO THE AREA. AS THE LINE OF SHOWERS DROPS TO THE SOUTH AND MEETS MODERATE SOUTHWEST FLOW EXPECT IT TO STRUGGLE TO HOLD TOGETHER OVER THE ADIRONDACKS AND SEE THE CHAMPLAIN VALLEY BECOME SHADOWED FROM THE SHOWERS WITH ONLY LIGHT SHOWERS EXPECTED. IN THE HIGHER TERRAIN HOWEVER EXPECT THE OROGRAPHIC LIFT TO COMBING WITH THE WEAK INSTABILITY ASSOCIATED WITH A 500MB VORT AXIS AND PRODUCE A FEW MODERATE RAIN SHOWERS ESPECIALLY OVER THE NORTHERN ADIRONDACKS AND SOUTHERN AND CENTRAL GREENS. HOWEVER WIDESPREAD PRECIPITATION WILL BE LIGHT EXPECTING TOTAL PRECIP AMOUNTS TO RANGE FROM 0.10" TO 0.30". SIMILAR TO THE PREVIOUS FORECAST WITH THE WEAKER INSTABILITY I CHOSE TO LEAVE OUT MENTION OF TS IN THE FORECAST BUT IT WOULDN`T SURPRISE ME TO HEAR A FEW RUMBLES OF THUNDER AS THE LINE MOVES THROUGH NEW YORK. BEHIND THE FRONT MONDAY NIGHT TEMPS WILL FALL INTO THE MID 50S IN THE CHAMPLAIN VALLEY AND UPPER 40S ELSEWHERE. WE WILL THEN MOVE INTO A PATTERN OF NEAR SEASONABLE TEMPS AND DRY WEATHER AS THE FLOW ALOFT BECOMES NORTHWEST AND SLIGHT UPPER LEVEL RIDGING BEGINS TO OCCUR. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... AS OF 355 AM EDT MONDAY... DRY AND SPRING-LIKE WEATHER EXPECTED THROUGH FRIDAY. ECMWF AND GFS MODELS ARE IN GENERALLY GOOD AGREEMENT THROUGH THE PERIOD. THUS...FORECASTER CONFIDENCE IS HIGH. ECMWF AND GFS MODELS SHOW A RIDGE OF HIGH PRESSURE WILL BE OVER THE REGION WEDNESDAY NIGHT THROUGH FRIDAY. A WEAK COLD FRONT WILL MOVE SOUTH FROM CANADA ON SATURDAY...SO HAVE GONE WITH CHANCE POPS FOR SHOWERS AND A SLIGHT CHANCE OF THUNDERSTORMS. MODELS SHOWING FRONTAL SYSTEM WILL BE OVER OR JUST SOUTH OF THE REGION ON SUNDAY...SO WILL CONTINUE WITH CHANCE POPS FOR RAIN SHOWERS ON SUNDAY. && .AVIATION /18Z MONDAY THROUGH SATURDAY/...
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THROUGH 18Z TUESDAY...MAINLY VFR CONDITIONS THROUGH THE PERIOD. HIGH PRESSURE HAS MOVED EAST OF THE REGION. SURFACE PRESSURE GRADIENT TIGHTENING INBETWEEN DEPARTING HIGH AND APPROACHING COLD FRONT. EXPECT SOUTH TO SOUTHWEST SURFACE WIND GUSTS OF 20 KNOTS OR GREATER THIS AFTERNOON THROUGH EARLY EVENING. STRONGEST WINDS WILL BE AT MSS WHERE GUSTS 30-35 KTS EXPECTED. A COLD FRONT WILL THEN MOVE INTO THE SAINT LAWRENCE THIS EVENING. EXPECT LIGHT RAIN SHOWERS TO DEVELOP ACROSS NORTHERN NEW YORK BETWEEN 00Z-03Z TUESDAY...AND THEN ACROSS VERMONT BETWEEN 03Z-06Z...WITH SOME LOCAL MVFR POSSIBLE...ESPECIALLY AT SLK. SHOWERS WILL END FROM NORTHWEST TO SOUTHEAST ACROSS THE REGION BETWEEN 05Z-10Z TUESDAY. DRIER AIR BUILDS IN TUESDAY MORNING WITH JUST SCATTERED STRATOCUMULUS EXPECTED MOST LOCATIONS AFTER 12Z. OUTLOOK 18Z TUESDAY THROUGH SATURDAY... 18Z TUESDAY-00Z SATURDAY...VFR CONDITIONS WITH WEAK SURFACE HIGH PRESSURE PREVAILING FOR MUCH OF THE PERIOD. 00Z SATURDAY-00Z SUNDAY...MAINLY VFR WITH AREAS OF MVFR/IFR IN SCATTERED SHOWERS AND THUNDERSTORMS.
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&& .FIRE WEATHER...
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&& .MARINE... AS OF 1144 AM EDT MONDAY...A LAKE WIND ADVISORY IS NOW IN EFFECT FOR LAKE CHAMPLAIN. WINDS ACROSS THE BROAD LAKE ARE JUST 15-25 KNOT THRESHOLD. THOUGH LAKE TEMPERATURES LIMIT MIXING DEPTH, A STRENGTHENING SOUTHWEST PRESSURE GRADIENT WILL INCREASE WINDS TO LAKE WIND ADVISORY CRITERIA. WINDS SHOULD BEGIN TO ABATE TO 10 TO 20 KNOTS LATER THIS EVENING AS A COLD FRONT MOVES THROUGH, WITH A WIND SHIFT TO NORTHWEST. WAVES OF 1 TO 2 FEET ARE EXPECTED, WITH THE HIGHEST WAVES PREFERENTIALLY ALONG SOUTH- FACING EXPOSURES. BOATERS SHOULD ALSO KEEP IN MIND THAT WATER TEMPERATURES REMAIN COLD - IN THE 40S. SWIMMING EARLY IN THE SEASON IS DISCOURAGED AS IMMERSION FOR PROLONGED PERIODS OF TIME COULD PRODUCE HYPOTHERMIA GIVEN THESE WATER TEMPERATURES. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...RED FLAG WARNING UNTIL 7 PM EDT THIS EVENING FOR VTZ001>012- 016>019. NY...RED FLAG WARNING UNTIL 7 PM EDT THIS EVENING FOR NYZ026>031- 034-035-087. && $$ SYNOPSIS...DEAL NEAR TERM...TABER SHORT TERM...DEAL LONG TERM...WGH AVIATION...RJS FIRE WEATHER...WFO BTV MARINE...LOCONTO

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