Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 022347 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 647 PM EST MON MAR 2 2015 .SYNOPSIS...
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ANY LINGERING SNOW SHOWERS WILL FADE AWAY THIS EVENING, LEAVING BEHIND CLEAR SKIES AS HIGH PRESSURE MOVES IN. THE HIGH PRESSURE WILL BE SHORT LIVED AS A STORM SYSTEM MOVES IN FROM THE WEST TUESDAY NIGHT AND WEDNESDAY. WIDESPREAD SNOW WILL DEVELOP LATE TUESDAY AND END AS A LITTLE BIT OF MIX OR RAIN SHOWERS WEDNESDAY MORNING. IT WILL BE MILD WEDNESDAY, BUT COLDER AIR RETURNS WEDNESDAY NIGHT. HIGH PRESSURE WILL THEN REMAIN IN CONTROL UNTIL THE END OF THE WEEK.
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&& .NEAR TERM /UNTIL 7 AM TUESDAY MORNING/...
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AS OF 647 PM EST MONDAY...COMPOSITE RADAR LOOP SHOWING SNOW SHOWER/SNOW SQUALL ACTIVITY DIMINISHING IN AREAL COVERAGE ACROSS THE REGION EARLY THIS EVENING DUE TO THE LOSS OF DAYTIME SURFACE HEATING. ALSO...EXPECTING SURFACE WIND GUSTS WILL ALSO DIMINISH AS SURFACE PRESSURE GRADIENT WEAKENS AS SURFACE HIGH PRESSURE AREA BUILDS EAST FROM THE GREAT LAKES AND OHIO VALLEY OVERNIGHT. HAVE LOWERED POPS ACROSS THE CHAMPLAIN VALLEY AND NORTHERN NEW YORK AS SNOW SHOWER ACTIVITY DIMINISHING AT THIS TIME. PREVIOUS DISCUSSION FROM 340 PM EST MONDAY...AS EXPECTED, CONVECTIVE SNOW SHOWERS HAVE DEVELOPED ACROSS THE AREA -- AS DENOTED BY THE VERY CELLULAR STRUCTURE EVIDENT ON RADAR. GOOD NEWS IS THAT NONE OF THE SNOW SHOWERS APPEAR TO BE PARTICULARLY HEAVY (THOUGH A 10-15 MINUTE PERIOD OF MODERATE SNOW WILL OCCUR) SO THEY SHOULD NOT IMPACT TRAVEL CONDITIONS MUCH. WINDS ARE A BIT ON THE GUSTY SIDE, AND I`VE SEEN A NUMBER OF 25-30KT GUSTS ACROSS THE REGION. AS WE GET CLOSER TO SUNSET, WE`LL LOSE THE DAYTIME HEATING AND ATMOSPHERIC MIXING SO BOTH THE SNOW SHOWERS AND WINDS WILL FADE AWAY GRACEFULLY. OTHERWISE FOR TONIGHT -- HIGH PRESSURE MOVES INTO THE REGION, SETTING UP SETTING UP FOR A MOSTLY CLEAR AND RATHER CHILLY NIGHT. LOOKS LIKE MOST AREAS SHOULD FALL WITHIN THE +/- 5F RANGE.
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&& .SHORT TERM /7 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/... AS OF 340 PM EST MONDAY...FAIRLY DECENT MODEL AGREEMENT, THOUGH SOME "DEVIL IN THE DETAILS" REGARDING THERMAL STRUCTURE ALOFT TUESDAY NIGHT WHICH DOES LEAD TO PRECIPITATION-TYPE ISSUES. LET`S JUST DISCUSS EACH 12-HOUR BLOCK OF TIME... TUESDAY: HIGH PRESSURE QUICKLY MOVES OFF TO THE EAST, SO WE START CLEAR BUT CLOUD OVER IN THE AFTERNOON. 925MB TEMPERATURES IN THE -12 TO -17C RANGE, WHICH WOULD SUPPORT HIGHS INTO THE MID 20S IN THE LOWER ELEVATIONS. FAIRLY ROBUST UPPER TROUGH AND ASSOCIATED SURFACE LOW WILL BE MOVING INTO THE GREAT LAKES REGION BY AFTERNOON. CONSIDERABLE WARM AIR ADVECTION, SO BY LATE AFTERNOON WE SHOULD SEE LIGHT SNOW BREAK OUT, ESPECIALLY FROM THE CHAMPLAIN VALLEY WESTWARD. TUESDAY NIGHT: VERY STRONG WARM AIR ADVECTION ONGOING. 850MB WINDS WILL INCREASE TO 45-55KTS OUT OF THE SOUTH/SOUTHWEST. THUS IT SHOULD GET FAIRLY BREEZY, IF NOT WINDY, IN THE CHAMPLAIN VALLEY. THINK WIND GUSTS TO 35 MPH ARE LIKELY. THE STRONG LOW/MID LEVEL JET WILL BRING WARMER AIR ALOFT, WHICH RESULTS IN A STRONG ISENTROPIC LIFT. SHOULD SEE A BURST OF MODERATE SNOW IN THE 8PM- 2AM TIMEFRAME PRETTY MUCH AREA WIDE. AFTER THAT TIME, TEMPERATURES IN THE 800-925MB LEVEL START TO SNEAK ABOVE 0C. THAT MEANS THE POTENTIAL FOR CHANGE OVER TO DIFFERENT PRECIP-TYPES. GOOD NEWS IS THAT AS TYPICAL WITH WARM AIR ADVECTION PRECIPITATION EVENTS, MOST OF THE PRECIPITATION IS OVER WITH PRIOR TO THE MIXING. MODELS ALSO TYPICALLY SHOW US GETTING MORE PRECIPITATION THAN REALITY DURING THESE WARM AIR ADVECTION SYSTEMS, SO I ENDED UP TAKING A MODEL BLEND AND THEN CUTTING BACK A LITTLE. THINK IN GENERAL 0.2 TO 0.3" OF "LIQUID", HOWEVER THE STRONG WINDS WILL RESULT IN SIGNIFICANT SHADOWING/DRYING IN THE CHAMPLAIN VALLEY, SO ONLY ABOUT 0.1" OR SO THERE. TRICKY PART IS TRYING TO ESTIMATE THE SNOW-LIQUID RATIO. BEST GUESS IS WE WILL BE SOMEWHERE IN THE 10-13:1 RANGE. THIS GIVES A GENERAL 2-4" OF SNOW, PRIOR TO ANY MIXING HAPPENING. FOR THE MIXING POTENTIAL, NOTED THE NAM, WHICH IS USUALLY A COLDER MODEL, WAS WARMEST AND BROUGHT THE MIX ALL THE WAY UP TO NORTHERN VT. GFS WAS COLDEST AND KEPT EVERYTHING TO THE SOUTH OF VERMONT. THE EURO AND THE LOCAL 12KM WRF WERE IN-BETWEEN. ENDED UP USING THE 12KM WRF FOR A LITTLE FINER RESOLUTION. BOTTOM LINE, ANY MIX SHOULD BE CONFINED TO SOUTH-CENTRAL VERMONT AND THE ST LAWRENCE VALLEY. AT THIS POINT WILL NOT ISSUE ANY WINTER WEATHER ADVISORIES. WE`LL SEE IF LATER MODEL RUNS HAVE A DIFFERENT TREND. A LITTLE NORTHWARD JOG IN THE MODELS WOULD MEAN A MUCH WETTER (AND LIKELY WARMER) SITUATION. WEDNESDAY: LIGHT PRECIPITATION IN THE MORNING SHOULD TAPER OFF AND END AS LIGHT RAIN SHOWERS FOR MOST EVERYONE. YEP, STILL LOOKING FOR A WONDERFULLY WARM DAY -- WELL, IF YOU CAN CALL 40S WARM. STUCK WITH A GUIDANCE MIX THAT HAS BURLINGTON REACHING THE LOWER 40S, BUT NOTED THAT SOME GUIDANCE INDICATED MID TO EVEN UPPER 40S. IT WILL ALL DEPEND ON HOW SOON THE COLDER AIR STARTS TO MAKE IT`S WAY IN. GIVEN WINDS TURNING WESTERLY DURING THE DAY (EG: DOWNSLOPING), AND A DRY SLOT LIKELY GIVING SOME BREAKS IN THE CLOUDS, I`D GIVE UPPER 40S ABOUT A 40% CHANCE OF HAPPENING. MAYBE THAT IS JUST ME WISH-CASTING ;) WEDNESDAY NIGHT: THE WARMTH IS SHORT LIVED. WINDS TURN NORTHWEST AND COLD-AIR ADVECTION CONTINUES. SHOULD DROP INTO THE TEENS ACROSS VERMONT, WITH LOWS CLOSER TO ZERO OUT IN THE ST LAWRENCE VALLEY. STILL SOME WIND AND SOME CLOUDS ABOUT AND PERHAPS A MOUNTAIN FLURRY. STUCK TO A GUIDANCE BLEND FOR TEMPERATURES. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 315 PM EST MONDAY... GIVEN THE LACK OF ACTIVE WEATHER EXPECTED IN THE EXTENDED I`LL FORGO DAILY DESCRIPTIONS IN FAVOR OF A BROAD GENERAL IDEA OF THE PATTERN FROM THURSDAY ONWARD. A BROAD NORTHERN UPPER LEVEL TROUGH WILL COMBINE WITH A BROAD DOME OF HIGH PRESSURE TO SUPPRESS ANY SYNOPTIC FORCING OF PRECIP WITH THE LONE EXCEPTION BEING A WEAK SHORTWAVE DISTURBANCE ON SATURDAY. THAT WILL BRING A CHANCE OF SNOW SHOWERS ESPECIALLY IN THE HIGHER TERRAIN OF THE ADIRONDACKS AND GREENS. CONCERNING TEMPERATURES... WE WILL SEE A GENERAL WARMING PATTERN WITH THURSDAY AND FRIDAY BEING THE COLDEST TWO DAYS WITH HIGHS IN THE LOW TO MID 20S WARMING TO MORE SEASONABLE TEMPS AROUND FREEZING TO THE MID 30S OVER THE WEEKEND. OVERNIGHT LOWS WILL BE QUITE CHILLY ON THURSDAY AND FRIDAY NIGHT AS MOSTLY CLEAR SKIES WILL ALLOW FOR GOOD RADIATIONAL COOLING BRING LOWS IN THE LOW SINGLE DIGITS ABOVE AND BELOW ZERO. INTO THE WEEKEND WITH THE WARMING TREND CONTINUING OVERNIGHT LOWS SHOULD WARM INTO THE MID TEENS TO NEAR 20 INSIDE THE CHAMPLAIN VALLEY. WINDS DURING THE PERIOD WILL BE GENERALLY LIGHT TO MODERATE WEST TO SOUTHWESTERLY UNDER THE UPPER LEVEL TROUGH AXIS WITH MOSTLY CLEAR SKIES EXCEPT FOR A SHORT PERIOD OF INCREASING CLOUDS NEAR THE INTERNATIONAL BORDER EARLY SATURDAY MORNING. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... THROUGH 00Z WEDNESDAY...PREDOMINANTLY VFR EXPECTED FOR MOST TAF SITES THROUGH THE PERIOD. SCATTERED SNOW SHOWERS AND GUSTY WEST/NORTHWEST WINDS WILL END DURING THE EVENING HOURS WITH ANY REDUCTIONS IN CEILINGS/VISIBILITIES GONE BY 02Z. OTHERWISE CONDITIONS IMPROVE TO VFR...SKIES BECOME CLEAR...AND WINDS GRADUALLY SLACKEN OVERNIGHT. WINDS WILL TURN SOUTHERLY ON TUESDAY AND BEGIN TO GUST TUESDAY AFTERNOON...WITH 15-20 KNOT GUSTS LIKELY...ESPECIALLY BTV/PBG/SLK. MID/HIGH DECK OF CLOUDS ALSO INCREASES AFTER 15-17Z...WITH LOWER DECK ALONG WITH A PERIOD OF SNOW MOVING INTO NORTHERN NY AND MSS/SLK AFTER 22Z. CONDIITONS SHOULD REMAIN DRY AT OTHER TAF SITES THROUGH ABOUT 00Z WEDNESDAY. OUTLOOK 00Z WEDNESDAY THROUGH SATURDAY... 00Z WEDNESDAY THROUGH 18Z WEDNESDAY... MVFR/IFR IN PERIODS OF LIGHT SNOW LIFTING TO VFR WEDNESDAY AFTERNOON AS PRECIPITATION MIXES WITH RAIN SHOWERS AND DISSIPATES. 18Z WEDNESDAY THROUGH 00Z FRIDAY...MAINLY VFR ALTHOUGH SOME PERIODS OF MVFR/IFR ARE POSSIBLE IN LIGHT SNOW SHOWERS AS SYSTEM SLIDES TO THE SOUTH. 00Z FRIDAY THROUGH 12Z SATURDAY...VFR UNDER RIDGE OF HIGH PRESSURE. 12Z SATURDAY ONWARD...MVFR/IFR POSSIBLE IN SNOW SHOWERS WITH FRONTAL SYSTEM. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...NASH NEAR TERM...WGH/NASH SHORT TERM...NASH LONG TERM...DEAL AVIATION...MUCCILLI

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