Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 211130 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 630 AM EST Tue Feb 21 2017 .SYNOPSIS... A weak disturbance and associated ribbon of mid level moisture will produce scattered rain showers late this afternoon across northern New York. This threat of showers will spread into Vermont overnight...with a few pockets of light freezing rain possible in the deeper valleys. Very minimal ice accumulation if any is anticipated...with temperatures in the upper 30s to mid 40s today. A big warming trend is expected for most of the week with more showers anticipated on Thursday Night into the weekend. && .NEAR TERM /THROUGH WEDNESDAY/...
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As of 621 AM EST Tuesday...Update to capture latest temps associated with sharp thermal inversion across our region. Currently Saranac Lake is 6F while atop Whiteface is 39F...indicating the warming aloft. Thinking deeper valleys will slowly mix out this morning as gradient increases between departing surface high pres and weak front approaching our region from the west. of forecast in good shape. 1031mb high pres centered over eastern VT this morning will shift east...while decaying short wave energy and associated ribbon of 850 to 500mb moisture approaches our western cwa by 00z Weds. Latest trends have been for this moisture to weaken as it encounter mid/upper level ridge across the ne CONUS and limit the overall qpf output over our forecast area. GFS/NAM and local WRF show up to 0.10 for mountain zones...with a trace to 0.05 most other locations. Developing 850mb southwest winds of 20 to 25 knots will produce modest low level warm air advection today with 925mb temps ranging from near 0c NEK to +6c western dacks/ anticipating a large spread in highs today. Also...playing a factor will be amount of sunshine and how quickly clouds spread from west to east across our cwa...but thinking highs range from the mid/upper 30s NEK to mid/upper 40s SLV/Western Dacks with maybe a few lower 50s near Potsdam/Edwards. Tonight...soundings show deep dry layer between 925mb and 700mb becoming saturated as moisture advection occurs on south to southwest winds. Thinking temps fall early as some evaporational cooling occurs...but with clouds and developing southerly flow of 10 to 20 knots...especially cpv/slv temps hold mainly in the mid/upper 30s to near 40f most of the night. East of the greens still looking at some pockets of <0C temps in the protected valley with the potential for some spotty freezing rain. Given the marginal temps and scattered precip/very light qpf...not anticipating widespread coverage of freeze rain and very minor ice accumulation. If needed will handle with a sps. Wednesday...low to mid level warm air advection continues with progged 925mb to 850mb temps climbing between 2c and 4c. However...soundings especially the nam shows plenty of low level moisture trapped below thermal inversion between surface and 850mb. Is this overdone again or do we see lots of low clouds and limited sun on Weds...keeping our temps on the cooler side of guidance with some areas of light precip. Soundings show this moisture mixing out...especially during the afternoon hours as top of the mixed layer winds increase between 15 and 20 knots and drier air aloft is advected toward the surface. Will trend toward the warmer side of guidance and keep forecast mainly dry at this time...with highs mainly lower 40s northeast kingdom to near 50f cpv/slv and western dacks.
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&& .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 358 AM EST Tuesday...Thursday will see another low pressure system from the Great Lakes region pass to the north of the CWA. Light showers, mainly in the northern half of the forecast area, are expected with the system passes north of the border and into northern Maine. QPF is minimal with this system with the Adirondacks seeing a couple tenths of an inch, the Northern Vermont counties seeing around a tenth and the rest of the state seeing only a few hundreths of an inch. Southerly flow will continue to boost temps well above seasonal norms for Thursday with highs in the 50`s for the majority of the area and overnight lows in the mid to upper 30`s. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 358 AM EST Tuesday...Friday sees low pressure tracking north and west of our region from the Great Lakes Friday through early Sunday morning. Models are in general agreement of a warm front lifting through the region Friday afternoon/evening with precipitation ramping up through the day Saturday with the peak Saturday afternoon/evening just ahead of the passage of a cold front. Winds out ahead of the front could lead to gusty conditions and potential advisory level winds especially across the Champlain Valley as the 00Z GFS indicates 850mb winds to reach 65 knots Saturday afternoon. After frontal passage, rain will switch over to snow showers Saturday night with the strong cold air advection. Very warm temperatures are expected Saturday ahead of the cold frontal passage. Temperatures overall look to be in the 50s with the Champlain Valley pushing a record breaking 60. A sharp cold front will drop temps quickly back into the 20s Saturday night. Possible flash freeze issues are possible with temperatures dropping so sharply after a moderate rainfall. Moving into next week, more seasonable weather will return for Sunday through Tuesday. && .AVIATION /12Z Tuesday THROUGH Saturday/...
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Through 12z Wednesday...Clouds increase from west to east across our taf sites today with cigs trending toward mvfr conditions between 03z-06z tonight. Expecting a brief period of light rain...possibly mixed with a few pockets of freezing rain at mpv/slk. Winds increase from the south/southwest this afternoon at 5 to 15 knots with a few localized higher gusts. Soundings show plenty of low level moisture developing from snow melt and precip...especially at slk/mpv after 06z tonight...which may support some ifr cigs toward sunrise Weds. Have mention cigs between 1500 and 2000 feet and will monitor moisture trends. Outlook 12z Wednesday through Saturday... Challenging aviation forecast with regards to low level moisture and potential mvfr/ifr cigs weds into thursday. Thinking mostly vfr/mvfr with pockets of mvfr/ifr in our mountains sites. A warm front lifting from southwest to northeast on Friday will produce additional showers along with some enhanced southerly winds. The turning wind profiles and rapid increase in speed with height will cause some areas of turbulence and shear on Friday Night into Saturday. Widespread gusty southerly winds likely on Saturday with areas of rain showers...producing localized mvfr/ifr cigs/vis in the heavier elements.
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&& .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Taber NEAR TERM...Taber SHORT TERM...MV LONG TERM...MV AVIATION...Taber is the U.S. government's official web portal to all federal, state and local government web resources and services.