Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 300842 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 442 AM EDT WED JUL 30 2014 .SYNOPSIS... LOW PRESSURE IN EASTERN CANADA WILL BRING TEMPERATURES A LITTLE BELOW NORMAL THROUGH TOMORROW NIGHT WITH CHANCES EACH DAY FOR AN AFTERNOON SHOWER OR THUNDERSTORM. A RETURN TO MORE NORMAL SUMMER TEMPERATURES IS EXPECTED FRIDAY AND INTO THIS WEEKEND... WITH A CONTINUED CHANCE FOR AN AFTERNOON AND EVENING SHOWER OR THUNDERSTORM. && .NEAR TERM /UNTIL 7 AM THIS MORNING/... AS OF 442 AM EDT WEDNESDAY... UPPER TROUGH/LOW OVER EASTERN CANADA IS IN CONTROL OF OUR WEATHER FOR THE NEAR AND SHORT TERM PERIODS. SHOWERS AND THUNDERSTORMS CONTINUED ALL NIGHT AROUND THE EASTERN GREAT LAKES WHERE WARM LAKE WATERS GENERATING INSTABILITY WITH COLD AIR ALOFT ALONG WITH A WEAK SHORT WAVE. THIS WAVE WILL PROGRESS SLOWLY NORTHEASTWARD TODAY FOLLOWED BY ANOTHER WAVE EVIDENT UPSTREAM OVER WISCONSIN EARLY THIS MORNING. THE HIGHER PROBABILITIES OF SHOWERS AND THUNDERSTORMS WILL BE FROM THE ADIRONDACKS WESTWARD TODAY BUT THERE ARE SOME INDICATIONS THEY MAY CLIP NW VT THIS EVENING SO KEEPING A SLIGHT CHANCE IN FOR THAT POSSIBILITY. MODELS VARY ON THE AMOUNT OF INSTABILITY AVAILABLE TODAY FROM A COUPLE HUNDRED J/LG CAPE TO NEAR 1000 IN THE ST LAWRENCE VALLEY PER THE ECMWF WHICH SEEMS REASONABLE GIVEN ONGOING CONVECTION AT THIS HOUR AND WHAT TRANSPIRED YESTERDAY TO OUR WEST. 850 TEMPS AROUND 9C SO HIGH TEMPS RANGING FROM THE UPPER 60S IN THE HIGHER TERRAIN TO MID 70S. && .SHORT TERM /7 AM THIS MORNING THROUGH FRIDAY/... AS OF 442 PM EDT TUESDAY... SECOND SHORT WAVE MOVES ACROSS THE REGION TONIGHT SO EVEN WITH WANING SURFACE BASED INSTABILITY WANING CAN`T RULE OUT A SHOWER OR THUNDERSTORM ESPECIALLY THIS EVENING AS TEMPS CONTINUE TO COOL ALOFT. A PARTLY CLOUDY NIGHT FOR MOST OF US WITH LOW TEMPS MAINLY IN THE 50S. ON THURSDAY...FINALLY THE STRONGEST WAVE WITH FAIRLY STRONG QG FORCING FROM VORTICITY ADVECTION AND BETTER INSTABILITY FROM COLD TEMPS ALOFT (-20C AT KMSS) BY 18Z THU. TIMING OF THIS FEATURE WILL PLAY A LARGE ROLE IN THE AMOUNT OF INSTABILITY WE SEE WITH MODELS SHOWING AN EARLY ARRIVAL WHICH WILL LIMIT CONVECTIVE POTENTIAL. ECMWF CONTINUES TO SHOW MORE INSTABILITY (UP TO 1500 J/KG) THAN MOST OF THE OTHER MODELS, BUT ALL SHOW SOME. SO SHOWERS ARE LIKELY FIRST IN NY IN THE MORNING AND REGION WIDE THROUGH MIDDAY WITH BEST CHANCE OF THUNDER MAINLY IN VT THROUGH THE AFTERNOON. WITH COLD POOL ALOFT AND LOWER FREEZING LEVELS (~8-9K FT) COULD SEE SOME SMALL HAIL WITH ANY STRONGER UPDRAFTS WHICH DO DEVELOP...BUT WILL LEAVE OUT FOR NOW. 850 TEMPS 8-11C SHOULD GIVE US HIGH TEMPS IN THE 70S. THURSDAY NIGHT SHORT WAVE IS EXITING SO CHANCES OF PRECIP DIMINISH WITH PARTLY CLOUDY SKIES AND TEMPS FALLING BACK INTO THE 50S. SOME PATCHY FOG POSSIBLE AGAIN. ON FRIDAY THE UPPER TROF IS WEAKENING AND LIFTING NORTH LEAVING US IN A BROAD SW FLOW ALOFT WITH 850 TEMPS UP AROUND 12-13C SHOULD GIVE US A PARTLY SUNNY DAY ` WITH HIGHS IN THE 70S TO AROUND 80 RIGHT ABOUT NORMAL FOR THE AUGUST 1. SOME SMALL CHANCE OF A SHOWER OR THUNDERSTORM BUT LESS THAN THURSDAY AS INSTABILITY IS WEAK. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... AS OF 356 AM EDT WEDNESDAY...LARGE SCALE FEATURES INDICATE A HIGHLY AMPLIFIED PATTERN WILL CONTINUE ACROSS THE CONUS WITH MID/UPPER LEVEL TROUGH ACROSS THE GREAT LAKES SANDWICHED BETWEEN STRONG RIDGES OVER THE WESTERN ATLANTIC AND THE INTER-MOUNTAIN WEST. THERE ARE INDICATIONS THOUGH THAT THIS PATTERN WILL RELAX A BIT LATER IN THE PERIOD WITH FLOW BECOMING MORE ZONAL...AT LEAST TEMPORARILY. WITH THE UPPER TROUGH OVER THE GREAT LAKES FOR MUCH OF THE PERIOD...EXPECT A FAIRLY ACTIVE PATTERN ACROSS THE NORTHEAST WITH RATHER MOIST SOUTHWEST FLOW AND SEVERAL EMBEDDED VORTS IN THE FLOW ALOFT BRINGING CHANCE OF SHOWERS AND PERHAPS A FEW STORMS TO THE REGION. PROBABILITIES FOR RAIN LOOK TO BE GREATEST DURING AFTERNOON HOURS EACH DAY...ASSOCIATED WITH TIME OF MAX HEATING. PRECIPITATION CHANCES OVERNIGHT/EARLY MORNING WILL BE LOWEST...WITH GENERALLY NO HIGHER THAN SLIGHT CHANCE INDICATED. TEMPERATURE PROFILES FAIRLY UNIFORM THROUGH THE PERIOD WITH 850 MB TEMPS MOSTLY BETWEEN 11-13C. WITH PARTIAL SUN...THIS SUPPORTS HIGHS IN THE MID 70S TO LOWER 80S. THESE READINGS CLOSE TO SEASONAL NORMS. MIN TEMPS EXPECTED TO RANGE FROM THE 50S IN THE MOUNTAINS TO LOWER AND MID 60S IN THE VALLEYS. && .AVIATION /09Z WEDNESDAY THROUGH SUNDAY/... THROUGH 06Z THURSDAY...FOG WITH LIFR/VLIFR CONDITIONS AT MPV/SLK THROUGH ABOUT 12Z. POTENTIAL FOR SOME FOG OR MIST AT REST OF SITES AS WELL OVERNIGHT...BUT POTENTIAL LOWER SO ONLY INCLUDED MENTION OF SOME SHALLOW FOG OR TEMPO MVFR. ONCE ANY FOG DISSIPATES BY 13Z...VFR CONDITIONS FOR THE REST OF THE PERIOD WITH SCT-BKN CUMULUS CLOUDS FOR THE AFTERNOON/EVENING ALONG WITH CHANCE SHOWER OR THUNDERSTORM WITH BRIEF MVFR CONDITIONS POSSIBLE AT MSS/SLK AFTER 18Z. HAVE INCLUDED MENTION VCSH TO ACCOUNT FOR THIS CHANCE. WINDS LIGHT AND VARIABLE OVERNIGHT THEN SOUTH TO SOUTHWEST 10 KTS OR LESS ON WEDNESDAY. OUTLOOK 06Z THURSDAY THROUGH SUNDAY... 06Z THU - 00Z FRI...SCATTERED SHOWERS AND THUNDERSTORMS WITH LOCALIZED MVFR/IFR CONDITIONS IN THE HEAVIER SHOWERS/STORMS. 00Z FRI ONWARD...MAINLY VFR ALTHOUGH BRIEF PERIODS OF MVFR POSSIBLE IN SCATTERED AFTERNOON SHOWERS OR THUNDERSTORM EACH DAY. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...SISSON NEAR TERM...SISSON SHORT TERM...SISSON LONG TERM...RJS AVIATION...RJS

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