Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 201943 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 343 PM EDT WED AUG 20 2014 .SYNOPSIS...
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SLOW MOVING LOW PRESSURE WILL BRING UNSETTLED WEATHER TONIGHT AND THURSDAY FOR MAINLY NORTHERN NEW YORK AND THE WESTERN HALF OF VERMONT. DRIER WEATHER WILL DEVELOP ON FRIDAY AS HIGH PRESSURE STARTS TO MOVE INTO THE AREA. THAT HIGH WILL STICK AROUND, GIVING US A LONG STRING OF DRY AND WARM WEATHER THAT WILL LAST FROM THE WEEKEND INTO THE MIDDLE OF NEXT WEEK.
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&& .NEAR TERM /UNTIL 7 AM THURSDAY MORNING/...
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AS OF 330 PM EDT WEDNESDAY...UPPER LOW CONTINUES TO MEANDER ACROSS THE NORTHERN GREAT LAKES REGION...WITH WEAK MID-LEVEL RIDGING IN PLACE ACROSS VT. ONGOING LINE OF SHOWERS AND EMBEDDED THUNDERSTORMS CONTINUES ACROSS CENTRAL NY STATE. IT HAS BEEN VERY SLOW TO MOVE NORTHWARD TODAY WITH LIGHT DEEP-LAYER WINDS PRODUCING SLOW STORM MOTIONS /LESS THAN 20 KTS/. AIRMASS IS SLIGHTLY MORE UNSTABLE FURTHER SOUTH...BUT LAPS CAPE VALUES RANGE FROM NIL ACROSS VT TO AROUND 1500 J/KG IN THE LOWER ST. LAWRENCE VALLEY AND ADIRONDACKS. HI-RES GUIDANCE CONSENSUS /HRRR...BTV-4 AND NMM-ARW/ LIFTS THIS AREA OF SHOWERS AND STORMS INTO NORTHERN NY LATER THIS AFTERNOON...WITH SHOWERS CONTINUING THROUGH THE OVERNIGHT. LOCALLY HEAVY DOWNPOURS ARE POSSIBLE AND WILL MENTION THIS IN HWO. 1-/3-HR FFG IS RELATIVELY HIGH (ABOUT 2.5" NEEDED IN 3 HR PERIOD) SO NOT THINKING ANY FLASH FLOODING. PRETTY GOOD AGREEMENT THAT THE RAIN SHIELD NEVER MAKES IT INTO THE CHAMPLAIN VALLEY UNTIL LATER THIS EVENING...AND AFTER MIDNIGHT INTO CENTRAL VERMONT. POPS RANGE FROM SLIGHT CHANCE/CHANCE ACROSS VERMONT TO LIKELY/LOW CATEGORICAL ACROSS THE ADIRONDACKS AND ST. LAWRENCE VALLEY. TEMPS TONIGHT TO RANGE FROM THE MID 50S ACROSS EASTERN VT WHERE BETTER RADIATIONAL COOLING IS EXPECTED TO THE MID/UPPER 60S IN NORTHERN NEW YORK UNDER OVERCAST.
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&& .SHORT TERM /7 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
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AS OF 330 PM EDT WEDNESDAY...AFOREMENTIONED UPPER LOW WILL CONTINUE TO BE THE PRIMARY DRIVER OF NORTH COUNTRY WEATHER THROUGH THURSDAY NIGHT. NAM/GFS ALL IN GOOD AGREEMENT THAT UPPER LOW OPENS UP/WEAKENS AS IT PROGESSES ACROSS THE NORTH COUNTRY THURSDAY INTO THURSDAY NIGHT. EXPECT SHOWERS TO ONCE AGAIN BE PRIMARILY FOCUSED ACROSS NORTHERN NY /LIKELY POPS/ ON THURSDAY...THOUGH THE BEST CHANCE FOR PRECIPITATION ACROSS VT IS ON THURSDAY. AIRMASS STILL IS FAIRLY MOIST WITH PWS AROUND 1.5" WITH 12Z NAM SHOWING CAPE VALUES SUPPORTIVE OF THUNDER. THE THUNDER RISK FOR THURSDAY IS LIMITED GIVEN EXPECTED EXTENSIVE CLOUD COVER AND ALSO LOSING BETTER DYNAMIC FORCING GIVEN WEAKENING UPPER LOW. THEREFORE I`VE ONLY GONE WITH SHOWERS THURSDAY. DESPITE 850 TEMPS OF +11 TO +13C...OVERCAST WILL ONLY KEEP TEMPS IN THE MID 70S. OVERALL DECREASING TREND IN POPS FOR THURSDAY NIGHT AS UPPER DISTURBANCE PIVOTS SOUTH OF THE NORTH COUNTRY. LARGE GRADIENT IN STORM TOTAL QPF /SPANNING WEDNESDAY AFTN THROUGH 12Z FRIDAY/. AMOUNTS RANGE FROM NIL ACROSS THE NORTHEAST KINGDOM...UNDER 0.5" FOR THE CHAMPLAIN VALLEY...TO UP TO 1.25" FOR THE ADIRONDACKS AND ST. LAWRENCE VALLEY AREAS. BY FRIDAY...AN AMPLIFIED UPPER RIDGE WILL BUILD SOUTHWARD TOWARD QUEBEC AS THE UPPER LOW PASSES INTO THE NORTH ATLANTIC AND WEAKENS TO AN OPEN WAVE. SOME INSTABILITY SHOWERS STILL POSSIBLE ON FRIDAY BUT SUBSIDENCE FROM BUILDING UPPER RIDGE WILL WIN OUT BY LATE IN THE DAY INTO THE EVENING. NOT MUCH CHANGE IN THERMAL PROFILES FOR FRIDAY...BUT MORE BREAKS IN CLOUDINESS SHOULD ALLOW FOR HIGHS TO TOP OUT IN THE MID TO UPPER 70S WITH 50S TO AROUND 60 FOR LOWS.
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&& .LONG TERM /SATURDAY THROUGH WEDNESDAY/...
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AS OF 330 PM EDT WEDNESDAY...12Z GUIDANCE FROM GFS, GFS ENSEMBLES AND ECMWF ARE ALL IN PRETTY DARN GOOD AGREEMENT WITH EACH OTHER AND THEIR INDIVIDUAL PREVIOUS RUNS, THUS I WOULD RATE MY CONFIDENCE IN THE FORECAST AS ABOVE NORMAL. IN SUMMARY, LARGE SCALE BLOCKING RIDGE DEVELOPS ACROSS THE EASTERN HALF OF THE COUNTRY, RESULTING IN DRY AND WARMING CONDITIONS INTO THE MIDDLE PART OF NEXT WEEK (SUMMER WILL HANG ON NEXT WEEK, WHICH MAKES THIS FORECASTER PERSONALLY HAPPY). WITH THE CLOSENESS AMONG THE MODELS, I SAW NO REASON TO SIGNIFICANTLY DEVIATE FROM THE PURE BLEND BETWEEN THEM ALL. HERE ARE THE DAILY SPECIFICS... SATURDAY...UPPER TROUGH WILL BE PUSHING SOUTH/EAST OF THE AREA. STILL SOME CYCLONIC FLOW ALOFT SO CAN`T RULE OUT AN ISOLATED LIGHT SHOWER OR SPRINKLE ACROSS MAINLY THE HIGHER TERRAIN, BUT IN GENERAL THE FORECAST IS A DRY ONE. CLOSER TO THE SURFACE, HIGH PRESSURE WILL BE SLOWLY NOSING DOWN FROM THE NORTH. THIS WILL RESULT IN A LIGHT EASTERLY FLOW. LUCKILY THIS TIME OF THE YEAR THE ATLANTIC OCEAN WATERS ARE AT THEIR WARMEST SO I DON`T EXPECT ANY ISSUES WITH WIDESPREAD LOW STRATUS DEVELOPING AS WE WOULD SEE IN THE SPRING OR EVEN EARLY SUMMER. HOWEVER IT WILL SET UP AN A TEMPERATURE GRADIENT WHERE IT WILL BE COOLEST EAST OF THE GREEN MOUNTAINS AND WARMEST IN THE ST LAWRENCE VALLEY. WITH 850MB TEMPERATURES RUNNING ABOUT 10-12C (EAST TO WEST), HIGHS SHOULD RANGE FROM THE LOWER 70S IN THE CONNECTICUT VALLEY TO UPPER 70S IN THE ST LAWRENCE VALLEY. SHOULD BE MOSTLY CLEAR SATURDAY NIGHT. VALLEY FOG WILL PROBABLY FORM AS TYPICAL THIS TIME OF YEAR. LOWS GENERALL IN THE 50S. SUNDAY...DITTO. MONDAY...SURFACE HIGH SHOULD BE PRETTY MUCH ON TOP OF THE AREA ALONG WITH STRONG RIDGING ALOFT. NET RESULT: LOTS OF SUN AND VERY LIGHT WINDS. 850MB TEMPERATURES RISE TO THE 12-13C RANGE AND WITH ATMOSPHERIC MIXING, WE SHOULD REALIZE THE FULL POTENTIAL OF WARMTH WITH HIGHS TOPPING OUT IN THE 70S TO LOWER 80S. MONDAY NIGHT ANOTHER REPEAT OF CLEAR/CALM/PATCHY FOG. TUESDAY...ALMOST IDENTICAL TO MONDAY, EXCEPT THE HIGH SINKS JUST A LITTLE SOUTH OF THE AREA ALLOWING THE FLOW TO TURN MORE SOUTHWESTERLY. IN RESPONSE, TEMPERATURES WILL RISE A DEGREE OR TWO FROM MONDAY. 850MB TEMPERATURES WILL BE UP AROUND 12-14C, SO LOOK FOR LOWER 80S TO BE MORE WIDESPREAD. STILL DEEP LAYER RIDGING AND A STRONG SUBSIDENCE INVERSION PERHAPS AS LOW AS 7500FT SO ANY DAYTIME CUMULUS THAT FORMS WILL BE VERY SHALLOW. TUESDAY NIGHT ANOTHER REPEAT OF MONDAY NIGHT WHICH IS A REPEAT OF SUNDAY NIGHT WITH IS A REPEAT OF SATURDAY NIGHT. WEDNESDAY...MODELS BEGIN TO DIVERGE SOME. GFS & IT`S ENSEMBLE MEAN KEEP THE UPPER RIDGE STRONG, MEANING LOTS O` SUN. ECMWF FLATTENS THE RIDGE IN RESPONSE TO A STRONG SHORTWAVE PASSING BY TO THE NORTH AND BRINGS IN SOME MOISTURE TO NORTHERN NY LATE IN THE DAY SUGGESTING A FEW SHOWERS/T-STORMS ABOUT. WITH THE BLEND I USED, I LEANED MORE TOWARD THE GFS SOLUTION, BUT PAINTED IN SOME 10-20% POPS IN NORTHERN NY. THE BASIC WORDED FORECAST WILL INDICATE A DRY DAY. 850MB TEMPERATURES RISE TO 14-16C OR SO, THUS EVEN MORE OF THE AREA WILL BE POKING ABOVE THE 80F MARK -- WITH EVEN A FEW LOCATIONS IN THE CHAMPLAIN/ST LAWRENCE VALLEY PUSHING INTO THE MID 80S.
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&& .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... THROUGH 18Z THURSDAY....CURRENTLY VFR ACROSS THE REGION. DAYTIME HEATING CUMULUS CLOUDS ARE DEVELOPING ACROSS THE HIGHER TERRAIN OF THE ADIRONDACKS AND ANTICIPATE ISOLATED SHOWERS SHOULD BE FORMING SOON (SO HAVE COVERED SLK WITH VCSH THE NEXT FEW HOURS). WATCHING SLOW MOVING AREA OF SHOWERS AND ISOLATED THUNDERSTORMS OFF TO THE WEST AND SOUTHWEST. ULTIMATELY THIS WILL MOVE INTO NORTHERN NEW YORK AND AFFECT TAF LOCATIONS SUCH AS KMSS & KSLK. HARD TO SPECIFICALLY PINPOINT EXACTLY WHERE CONVECTION WILL BE AT EXACT TIMES, SO IN GENERAL THE CONFIDENCE IN THE OVERALL SPECIFICS IN THE FORECAST IS NOT ALL THAT GREAT. HAVE INCLUDED THE VCSH/VCTS. TOOK A STAB AT A LITTLE MORE WIDESPREAD LIGHT SHOWER ACTIVITY OCCURRING AFTER 00Z FOR THE NORTHERN NEW YORK LOCATIONS WITH PREDOMINANTE -SHRA IN THE TAFS. FOR THE CHAMPLAIN VALLEY AND POINTS EAST, THE SHOWERS WON`T BE GETTING EVEN CLOSE ENOUGH UNTIL WELL AFTER 00Z AND PROBABLY WON`T BE AS CONCENTRATED. THUS VCSH FOR A GOOD CHUNK OF THE NIGHT. GUIDANCE AGAIN HITS MONTPELIER (MPV) HARD WITH LIFR CONDITIONS IN BOTH CEILING AND VISIBILITY WITH DENSE FOG. THINK IT WILL BE MORE STRATUS AND LESS FOG TONIGHT, BUT THE END RESULT COULD BE THE SAME WITH A CLOUD DECK JUST A FEW HUNDRED FEET ABOVE THE GROUND. FOR THURSDAY, THE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS NOW OFF TO OUR WEST WILL BE MORE OR LESS OVER THE AREA. KEPT IT VFR FOR VERMONT SIDE, THOUGH MVFR VISIBILITIES AND CEILINGS WILL PROBABLY BE ACROSS NORTHERN NEW YORK. OUTLOOK 18Z THURSDAY THROUGH MONDAY... 18Z THUR TO 00Z SAT...AREAS OF MVFR WITH ANY SHOWERS. 00Z SAT ONWARD...VFR, EXCEPT IFR IN LATE NIGHT VALLEY FOG (PRIMARILY MPV AND SLK). && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...NASH NEAR TERM...LOCONTO SHORT TERM...LOCONTO LONG TERM...NASH AVIATION...NASH

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