Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 230526 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 126 AM EDT WED JUL 23 2014 .SYNOPSIS... A WEAK AREA OF HIGH PRESSURE WILL BE OFF THE NEW ENGLAND COAST OVERNIGHT. A COLD FRONT WILL MOVE SOUTH FROM CANADA ON WEDNESDAY. THIS COLD FRONT WILL BRING SHOWERS AND THUNDERSTORMS TO THE NORTH COUNTRY WEDNESDAY AND WEDNESDAY EVENING. SOME OF THE THUNDERSTORMS WILL PRODUCE STRONG GUSTY WINDS AND LOCALLY HEAVY RAINFALL. A HIGH PRESSURE AREA WILL BUILD INTO THE REGION ON THURSDAY BRINGING COOLER AND DRIER AIR TO THE NORTH COUNTRY...WITH HIGH TEMPERATURES IN THE 70S ON THURSDAY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 1051 PM EDT TUESDAY...AFTER REACHING 90F AT BTV THIS AFTERNOON...DAYTIME CUMULUS CLOUDS HAVE LARGELY DISSIPATED EARLY THIS EVENING WITH ONSET OF DIURNAL COOLING CYCLE. WILL HAVE A QUIET ALBEIT MODERATELY HUMID OVERNIGHT PERIOD WITH JUST SOME PREVAILING THIN CIRRUS CLOUDS...MAINLY ACROSS THE NORTHERN HALF OF THE FORECAST AREA. LEADING BAND OF SHOWERS COULD REACH THE ST. LAWRENCE VALLEY BY 10-12Z...SO DID INCLUDE 20-30 POPS FOR WRN ST. LAWRENCE COUNTY DURING THAT TIME FRAME. SURFACE WINDS WILL CONTINUE LIGHT SOUTH TO SOUTHWEST. THESE FACTORS WILL HOLD OVERNIGHT LOWS NEAR 70F IN THE CHAMPLAIN AND ST. LAWRENCE VALLEYS...AND GENERALLY MID-UPR 60S ELSEWHERE ACROSS THE FORECAST AREA. SIMILAR TO LAST NIGHT...ANTICIPATE SOME PATCHY FOG DEVELOPMENT AFTER MIDNIGHT IN THE CT VALLEY AND NEARBY RIVER VALLEYS. && .SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/... AS OF 402 PM EDT TUESDAY...A COLD FRONT WILL BE ENTERING THE SAINT LAWRENCE VALLEY IN NORTHERN NEW YORK WEDNESDAY MORNING. CONDITIONS STILL REMAIN FAVORABLE FOR STRONG TO SEVERE THUNDERSTORMS ACROSS THE REGION ON WEDNESDAY...WITH 0-6KM BULK SHEAR VALUES OF 30-40 KTS AND CAPES OF 1000-2000 J/KG. PWAT VALUES OF AROUND 1.8 TO NEARLY 2.0 INCHES. WET BULB ZERO VALUES ARE WELL ABOVE 11000 FT AND APPROACH 12000 FT...SO HAIL THREAT IS MINIMAL. THE MAIN THREAT FROM SOME OF THE STRONGER THUNDERSTORMS ON WEDNESDAY WILL BE FOR STRONG GUSTY WINDS AND LOCALLY HEAVY RAINFALL. UNIDIRECTIONAL FLOW OF 30-40 KNOTS ALOFT ALSO SUGGESTS THESE STORMS WILL BE MOVING ALONG...SO NOT CONCERNED WITH ANY FLASH FLOODING ISSUES AT THIS TIME. COULD SEE SOME PONDING OF WATER IN POOR DRAINAGE AREAS. HAVE INCLUDED ENHANCED WORDING IN THE FORECAST FOR WEDNESDAY FOR STRONG GUSTY WINDS AND LOCALLY HEAVY RAINFALL. STILL EXPECTING SOME SHOWERS AND STORMS TO LINGER INTO EARLY WEDNESDAY EVENING...BUT EXPECTING MOST OF THE ACTIVITY WILL BE DONE BY MIDNIGHT WEDNESDAY NIGHT. HIGH PRESSURE TO BUILD INTO THE REGION ON THURSDAY AND REMAIN THROUGH THURSDAY. MUCH COOLER AND DRIER AIR WILL MOVE INTO THE REGION ON THURSDAY WITH HIGHS ONLY IN THE 70S. LOWS THURSDAY NIGHT WILL BE IN THE 40S TO LOWER 50S. && .LONG TERM /FRIDAY THROUGH TUESDAY/... AS OF 318 PM EDT TUESDAY...MOVING ON INTO FRIDAY AND SATURDAY...PARTLY SUNNY AND PLEASANT CONDITIONS CONTINUE WITH JUST A SLIGHT CHANCE FOR A SHOWER ACROSS THE HIGHER TERRAIN FRIDAY AFTERNOON AS WE REMAIN UNDER CYCLONIC FLOW ALOFT FROM A UPPER LOW TO OUR NORTH. HIGHS WILL RANGE RIGHT AROUND NORMAL IN THE MID 70S TO LOW 80S...AND LOWS IN THE 50S. PATTERN BECOMES A BIT MORE UNSETTLED AND UNCERTAIN FROM SATURDAY NIGHT ONWARD WITH LATEST MEDIUM RANGE GUIDANCE AT ODDS IN THE HANDLING OF A SHORTWAVE ENTERING THE CANADIAN PRAIRIES FRIDAY INTERACTING WITH THE UPPER LOW/TROUGH OVER EASTERN CANADA. OVERALL THE GFS PHASES THE SHORTWAVE INTO THE TROUGH MUCH FASTER THAN THE ECMWF...SHIFTING IT INTO THE GREAT LAKES REGION SUNDAY MORNING. ECMWF SOLUTION SUPPORTS THIS IDEA AS WELL...JUST ONLY 24 HOURS LATER. FOR NOW WILL SPLIT THE DIFFERENCE ON TIMING AND CONTINUE TO OFFER CHANCE POPS FOR SUNDAY/SUNDAY NIGHT. BETTER SUPPORT FOR MORE WIDESPREAD SHOWERS AND STORMS COMES MONDAY WITH GOOD MODEL AGREEMENT AS THE UPPER LOW OVER JAMES BAY RETROGRADES WESTWARD AND DEEPENS OVER THE GREAT LAKES SUNDAY NIGHT LEAVING THE NORTH COUNTRY UNSETTLED IN SOUTHWEST FLOW ALOFT. SYSTEM IS SLOW TO SHIFT EAST SO WE COULD BE LOOKING AT A WET FEW DAYS TO START THE WORK WEEK. OVERALL...RIGHT NOW DYNAMICS NOT OVERALL STRONG SO NOT THINKING ANYTHING TOO SIGNIFICANT...JUST SOME GARDEN VARIETY SHOWERS THUNDERSTORMS. && .AVIATION /05Z WEDNESDAY THROUGH SUNDAY/... THROUGH 06Z THURSDAY...VFR OVERNIGHT. COULD SEE OCCASIONAL PERIODS OF MIST AT SLK GIVEN CALM WINDS THERE NOW...BUT NOT LIKELY TO DEVELOP IFR OR LOWER VISIBILITIES AS LOW-LEVEL WINDS INCREASE (ALREADY 25 KTS AT 1 KFT SAMPLED BY KTYX RADAR). INCLUDED LLWS AT SLK GIVEN DECOUPLED/CALM WINDS. MORE ACTIVE AVIATION PERIOD ANTICIPATED WEDNESDAY WITH POTENTIAL FOR STRONG/LOCALLY SEVERE THUNDERSTORMS AS COLD FRONT MOVES ACROSS THE REGION. UNCERTAINTY IN SPECIFIC TIMING THIS FAR OUT BUT FOR NOW WILL SHOW TIMING WINDOW WITH VCSH: BETWEEN 13Z MSS- SLK...14-16Z PBG- BTV- RUT-MPV. THREAT OF THUNDER LOOKS TO END 20-21Z MSS- SLK...21-22Z PBG-BTV AND 00Z RUT-MPV. THOUGH LIKELY VFR MOST OF THE TIME...ANY THUNDERSTORM HAS POTENTIAL FOR BRIEF IFR VISIBILITY IN HEAVY RAIN WITH STRONGER STORMS PRODUCING LLVL TURBULENCE AND MORE LIMITED THREAT OF HAIL. PRE-FRONTAL SOUTH WINDS 10-12KTS WITH OCCASIONAL GUSTS TO 20-22 KTS...BUT NOTABLE WIND SHIFT TO NORTHWEST AROUND 10 KTS WITH FRONTAL PASSAGE. NORTH WINDS LOOK TO DROP OFF SOME WEDNESDAY EVENING WITH HIGH PRESSURE BUILDING IN...THOUGH INDICATIONS FROM BUFKIT SOUNDINGS AND CURRENT POST- FRONTAL OBS ACROSS ON/NORTHERN GREAT LAKES SUGGEST LOWER CEILINGS WILL LINGER WELL AFTER FRONTAL PASSAGE. OUTLOOK 06Z THURSDAY THROUGH SUNDAY... 06Z THU - 12Z THU...VFR/MVFR DUE TO LOWER CEILINGS. POTENTIAL FOR IFR/LOWER VISIBILITY IN MIST/FOG IF MORE CLEARING THAN ANTICIPATED. 12Z THU - 00Z MON...VFR UNDER HIGH PRESSURE. LATE NIGHT AND EARLY MORNING IFR OR LOWER VISIBILITY IN FOG/MIST AT MPV AND SLK POSSIBLE. AN ISOLATED AFTERNOON SHOWER OVER THE HIGHER TERRAIN IS POSSIBLE FRIDAY. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...WGH NEAR TERM...BANACOS SHORT TERM...WGH LONG TERM...LAHIFF AVIATION...KGM/LOCONTO

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