Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 241917 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 317 PM EDT THU JUL 24 2014 .SYNOPSIS... HIGH PRESSURE WILL RETURN TO THE REGION TODAY THROUGH SATURDAY WITH MAINLY DRY WEATHER AND SEASONABLY MILD TEMPERATURES. UNSETTLED CONDITIONS THEN RETURN FROM SUNDAY ONWARD INTO THE MIDDLE PORTIONS OF NEXT WEEK AS UPPER LEVEL LOW PRESSURE EVOLVES ACROSS THE GREAT LAKES AND TRANSPORTS MOISTURE NORTHWARD INTO THE REGION. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 115 PM EDT THURSDAY...SHALLOW CUMULUS HAS FORMED OVER THE MOUNTAINS EARLY THIS AFTERNOON AND SHOULD PERSIST UNTIL JUST AROUND SUNSET WHEN THEY WILL DISSIPATE. HAVE TWEAKED SKY GRIDS TO ACCOUNT FOR A BIT MORE CLOUD COVER OVER THE MOUNTAINS THIS AFTERNOON. COLD AIR ADVECTION REMAINS RATHER NOTICEABLE THIS AFTERNOON AND HAVE CUT BACK ON MAXIMUM TEMPERATURES BY ANOTHER TWO DEGREES. REST OF FORECAST REMAINS UNCHANGED. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... AS OF 345 AM EDT THURSDAY...QUIET/CALM WEATHER THEN CONTINUES TONIGHT WITH BROAD SURFACE HIGH PRESSURE IN CONTROL. LIGHT WINDS AND GENERALLY CLEAR SKIES SHOULD FOSTER AMPLE RADIATIVE PROCESSES WITH PLEASANTLY COOL LOWS IN THE 45 TO 55 RANGE EXPECTED. PATCHY DENSE FOG ALSO A GOOD BET...ESPECIALLY IN CLIMATOLOGICALLY FAVORED LOCALES. BY FRIDAY ANOTHER NICE DAY ON TAP FOR THE AREA AS HIGH PRESSURE REMAINS IN CONTROL FOR THE MOST PART WITH HIGHS TOPPING OUT FROM 75 TO 82 UNDER PARTLY SUNNY SKIES. A WEAK SHORTWAVE AND ASSOCIATED 850 TD BUBBLE WILL CROSS THE AREA DURING THE AFTERNOON AND MAY SPARK AN ISOLATED SHOWER OR TWO ACROSS THE HIGHER TERRAIN OF THE NORTHERN MOUNTAINS BUT THE MAJORITY OF THE AREA...ESPECIALLY THE BROADER VALLEYS WILL REMAIN LARGELY DRY. THEN ANOTHER PARTLY CLOUDY/CL NIGHT ON TAP IN THE WAKE OF THE WEAK SHORTWAVE FRIDAY NIGHT. PATCHY FOG AGAIN A GOOD BET HERE AND THERE WITH LOWS A TAD MILDER UNDER LIGHT SOUTHERLY RETURN FLOW...48 TO 58. BY SATURDAY TEMPERATURES CONTINUE TO GRADUALLY WARM AS SURFACE HIGH SLIDES OFFSHORE UNDER GRADUALLY DEEPENING SOUTH TO SOUTHWESTERLY FLOW. AN APPROACHING MID LEVEL SHORTWAVE FROM THE GREAT LAKES WILL LIKELY BEGIN TO SPREAD SOME CLOUDS AND A FEW SHOWERS INTO OUR FAR WESTERN COUNTIES TOWARD LATE AFTERNOON OR EARLY EVENING BUT THE MAJORITY OF THE AREA WILL AGAIN REMAIN DRY AS HIGHS TOP OUT FROM 77 TO 84. && .LONG TERM /SUNDAY THROUGH THURSDAY/...
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AS OF 315 PM EDT THURSDAY...PRIMARY WEATHER NEWS FOR THE EXTENDED PERIOD IS THE ANTICIPATED DEVELOPMENT OF A LONG-WAVE TROUGH ACROSS THE EASTERN THIRD OF THE COUNTRY THAT WILL RESULT IN A GENERALLY UNSETTLED AND SLIGHTLY COOLER THAN NORMAL FIRST FEW DAYS OF THE WEEK. PRIMARY 12Z GUIDANCE (GFS & ECMWF) STILL IN LINE WITH EACH OTHER AND WITH THEIR RESPECTIVE PRIOR RUNS WITH LARGE SCALE PICTURE WITH THE LONG-WAVE TROUGH. STILL OFFER SLIGHTLY DIFFERENT TIMING WITH RESPECT TO INDIVIDUAL SHORTWAVES THAT WILL BE ZIPPING THROUGH THE FLOW, AND IT`S REALLY THOSE SHORTWAVES THAT WILL DRIVE THE WEATHER WE SEE. BECAUSE OF THE OVERALL SIMILARITY BETWEEN MODELS, I POPULATED THE GRIDDED FORECAST DATASET WITH A BLEND OF THEM ALL. HERE ARE THE DAILY SPECIFICS: SUNDAY...TIMING IS STILL UNCERTAIN, BUT THE MORNING HOURS WE MAY BE DEALING WITH A BATCH OF SHOWERS AND PERHAPS AN EMBEDDED T-STORM THANKS TO A SHORTWAVE PASSING ACROSS THE REGION. WITH SOME BREAKS OF SUN IN THE AFTERNOON THAT COULD BUBBLE UP SOME SCATTERED SHOWERS OR T-STORMS. SURFACE BASED INSTABILITY GUIDANCE FROM THE GFS SHOWS SOME MODERATE INSTABILITY, BUT THAT BEGINS TO WANE BY LATE AFTERNOON. PART OF THIS INSTABILITY MAY BE DRIVEN IN THE MODELS BY THE RATHER HIGH SURFACE DEWPOINTS (MID-UPPER 60S). BEST MID LEVEL WINDS AND SHEAR VALUES ARE SOUTH AND EAST OF THE AREA, SO ANY CONVECTION WE DO SEE SHOULD NOT BE ALL THAT ORGANIZED OR STRONG. THAT SAID, BECAUSE OF THE UNCERTAIN TIMING OF THE SHORTWAVE, IF THE SHORTWAVE COMES THROUGH A LITTLE SLOWER, THEN SUNDAY AFTERNOON COULD BE MORE ACTIVE CONVECTIVELY. IN THE END, I JUST PAINTED IN LIKELY LEVEL POPS FOR THE ENTIRE DAY. NO REASON TO TRY TO GET MORE CUTE THAN IS NECESSARY AT THIS POINT. 850MB TEMPERATURES AROUND 13-14C, WHICH UNDER FULL SUNSHINE WOULD SUPPORT LOW/MID 80S FOR HIGHS. HOWEVER, CLOUDS SHOULD HOLD TEMPERATURES BACK TO ABOUT 80F, THOUGH THAT WILL BE HIGHLY DEPENDANT ON WHAT WE SEE FOR SUN. COULD BE HIGHER. COULD BE LOWER. SUNDAY NIGHT/MONDAY...NEXT SHORTWAVE ROUNDING THE BASE OF THE UPPER TROUGH COMES INTO THE REGION. TIMING DIFFERENCES BETWEEN THE MODELS, SO AGAIN WON`T TRY TO SLICE THE BALONEY TOO THIN. SO SOMETIME IN THIS PERIOD WE`LL SEE ANOTHER BATCH OF SHOWERS WITH EMBEDDED T-STORMS ROLL THROUGH. INSTABILITY PARAMETERS IN THE MODELS ARE NOT IMPRESSIVE AT ALL, SO I JUST CALLED IT "SLIGHT CHANCE" FOR T-STORMS. AGAIN, A BUNCH OF CLOUDS AND WITH THE MID/UPPER LEVEL TEMPERATURES FALLING DUE TO THE SLOWLY APPROACHING LONGWAVE TROUGH (850MB TEMPERATURES SHOULD BE 10-12C), MONDAY IS LOOKING A LITTLE COOLER THAN SUNDAY - HIGHS IN THE MID 70S, ABOUT 5-7F BELOW NORMAL. TUESDAY/WEDNESDAY...LONGWAVE TROUGH AXIS WILL BE JUST OFF TO OUR WEST, OVER THE EASTERN GREAT LAKES. AT THIS POINT THE MODELS AREN`T SHOWING ANY SIGNIFICANT SHORTWAVES MOVING THROUGH THE FLOW, SO THE PRIMARY TRIGGER MECHANISM FOR ANY CONVECTION WILL BE DAYTIME HEATING. SO HAVE PAINTED IN CHANCE LEVEL POPS DURING THE DAY AND MINIMAL POPS FOR TUESDAY & WEDNESDAY NIGHTS. 850MB TEMPERATURES CONTINUE TO FALL, AND WILL BE DOWN AROUND 10C. THIS WILL SUPPORT TEMPERATURES IN THE MID 70S AS ADDITIONAL SUN WILL OFFSET THINGS A BIT. THURSDAY...LONGWAVE TROUGH PATTERN LOOKS TO "RELOAD" ACROSS THE CENTRAL PLAINS, SO WEAK RIDGING DEVELOPS OVER US. SHOULD BE THE DRIEST OF THE EXTENDED FORECAST PERIOD, THOUGH ANTICIPATE DAYTIME HEATING TO AGAIN RESULT IN A FEW SHOWERS ESPECIALLY ACROSS THE HIGHER TERRAIN. 850MB TEMPERATURES RISE BACK UP TO 12-13C, SO HIGHS WILL BE CLIMBING CLOSER TO NORMAL WITH UPPER 70S TO PERHAPS LOW 80S.
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&& .AVIATION /19Z THURSDAY THROUGH TUESDAY/... THROUGH 18Z FRIDAY...CURRENTLY VFR, WITH DAYTIME CUMULUS FOCUSSED MORE ACROSS THE HIGHER TERRAIN. LOOKS LIKE A LAKE BREEZE IS FORMING ALONG LAKE CHAMPLAIN AS WELL. WHAT YOU SEE IS WHAT YOU GET FOR THE REST OF THE AFTERNOON. CLOUDS WILL MELT AWAY JUST PRIOR TO SUNSET AND WINDS WILL BE NEAR CALM IN MOST AREAS. PRIMARY FORECAST CHALLENGE CONCERNS POTENTIAL FOR PATCHY FOG LATE TONIGHT. THERE ARE INDICATIONS IN THE GUIDANCE THAT THE DRIER AIR COMING INTO THE AREA TODAY WILL LIMIT THE POTENTIAL FOR FOG. SOME OTHER INDICATIONS THAT THERE WILL BE 5-10KTS OF WIND A FEW HUNDRED FEET ABOVE GROUND THAT WOULD LEAN TOWARD MORE OF A STRATUS SITUATION THAN FOG. IN ANY REGARD, ONLY SLK AND MPV ARE AT RISK FOR ANY FOG/STRATUS. THINK FOG WILL REDUCE VISIBILITIES PRIMARILY TO MVFR LEVELS, THOUGH WITH A LITTLE MORE MOISTURE AROUND MPV DUE TO RECENT RAIN, THINK IFR CEILING WILL FORM LATE TONIGHT FOR JUST A FEW HOURS. BY 12Z FRIDAY, WE ARE BACK TO VFR AREA WIDE. OUTLOOK 18Z FRIDAY THROUGH TUESDAY... 18Z FRI - 00Z SUN...VFR. PERHAPS A TOUCH OF OVERNIGHT FOG AT MPV AND/OR SLK. 00Z SUN ONWARD...TRENDING INCREASINGLY UNSETTLED. THOUGH MOSTLY VFR...PERIODIC SHOWERS/STORMS WITH POSSIBLE BRIEF MVFR/IFR VISIBILITY RESTRICTIONS. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...JMG NEAR TERM...EVENSON SHORT TERM...JMG LONG TERM...NASH AVIATION...NASH

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