Area Forecast Discussion
Issued by NWS Burlington, VT

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793 FXUS61 KBTV 220917 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 417 AM EST Wed Feb 22 2017 .SYNOPSIS... Much above normal temperatures continue into the weekend with scattered showers and areas of fog possible...especially tonight into Thursday. A strong cold front will produce gusty winds and a line of showers on Saturday afternoon and evening...with much cooler temperatures by Sunday. The combination of snow melt and precipitation will result in localized ice jam threat with the potential for isolated low lying flooding as we head into the weekend. && .NEAR TERM /THROUGH THURSDAY/... As of 401 AM EST Wednesday...Fast westerly flow aloft continues today...while low level winds are from the south/southwest resulting in moisture and warm air advection. Have noted plenty of low clouds and fog upstream associated with higher moisture content and warm air moving over cold snow pack...especially MI. Soundings indicating the threat for fog/br increases by tonight...especially deeper/protected mountain valleys and this trend may continue into Thursday. Progged 850mb temps warm between 2-4c today...but with all the clouds mixing maybe limited...so will keep temps mid 40s to lower 50s most locations. An isolated shower cannot be ruled out over the terrain...but any precip will be light. Tonight...the potential for fog/br increases as temps cool back into the 30s and lower 40s...but surface dewpoints continue to increase on southerly winds. Will continue to mention patchy to areas of fog/br...given sounding profiles...with mostly likely locations the SLV/northern Dacks and parts of central/northern VT valleys. Thursday...temps become very tricky as we continue to be under moderate low level warm air advection on gusty south/southwest winds. However...these winds continue to advect higher moisture into our region with surface dwpts in the upper 30s to mid 40s...supporting areas of low clouds and fog...which may limit surface heating. Area soundings show lots of moisture between surface and 850mb on Thursday...associated with strong moisture advection on 925mb to 850mb winds of 35 to 45 knots. Soundings support localized wind gusts btwn 30 and 35 knots in the SLV...dacks and parts of the CPV on Thursday afternoon. Areas of drizzle will be possible in the mountains on Thursday. For temps will fall high resolution 2m temps...which support mid 40s mountain valleys to l/m 50s warmer valley locations. A weak surface boundary along with increasing mid level moisture will increase the threat for showers on Thursday afternoon...as pws surge between 0.75 and 0.95. Have mention chance to low likely pops...but best forcing associated with 5h vort and better moisture looks to pass just to our north. QPF will be <0.10. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... As of 412 AM EST Wednesday...Friday brings with it an increase in clouds and precipitation as a passing upper ridge gives way to an upper through and a warm front from an associated rapidly developing low over the midwest US late in the day. Light precipitation should move throughout the later part of the day through the region, although QPF looks to only be about .10 on average for most locations. Slightly cooler temps are expected for Friday as increased cloud cover along with the late influence of the advancing warm front will see daytime highs in the mid 40`s while temps should continue to rise in central and western parts of the CWA while the eastern portion should see some cooling overnight, leading to overnight lows ranging in the mid 40`s to upper 30`s. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 412 AM EST Wednesday...Saturday afternoon/evening should see the precipitation ramping up just ahead of the passage of a cold front from the associated occulded system pushing to the north and west of our area. Most of the CWA should see a half to three quarters on an inch of precipitation during this timeframe. Winds out ahead of the front could lead to a narrow band of gusty conditions and advisory level winds especially across the Champlain and St Lawrence Valleys as the 00Z GFS continues to indicate 850mb winds reaching 65 and 70 knots in the respective valleys Saturday afternoon. After frontal passage, rain will switch over to snow showers late Saturday night/Sunday morning with moderate cold air advection. Very warm temperatures are expected Saturday ahead of the cold frontal passage. Temperatures overall look to be in the mid to upper 50s with the Champlain and St Lawrence Valleys pushing a record breaking 60. The sharp cold front will drop temps quickly back into the upper 20s and lower 30`s late Saturday night. Flash freeze issues are possible in some locations with temperatures dropping so sharply after a moderate rainfall. Next week see a return to more seasonable and quiet weather Sunday through Tuesday before another system moves in at the end of the period on Wednesday. && .AVIATION /09Z Wednesday THROUGH Sunday/... Through 06z Thursday...VFR conditions continue as the weak shortwave trough pushes across the area. Light drizzle may continue over the next couple of hours by dry low levels will prevent any significant precip from reaching the ground. The models have been consistent with the potential for some MVFR clouds through the morning hours however the source region for our airmass doesn`t support this so I`ve opted to hover right on the border with clouds in the 3000-4000ft elevation. Winds will continue to be generally south to southwesterly with gusty winds possible at BTV only due to funneling of the Champlain Valley. Tomorrow evening with warm dew points and moisture available from the melting snowpack the potential will exist for some light ground fog to develop. Winds and cloud cover will be the limiting factor in how much fog develops and thus visibility restrictions. Outlook 06z Wednesday through Sunday... Thursday...VFR/MVFR with pockets of MVFR/IFR in our mountains sites. Friday - Saturday...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. Sunday...VFR/MVFR conditions possible, especially in mountains snow showers. && .HYDROLOGY... As of 400 aM EST Wednesday...Above normal temperatures will continue to melt a significant amount of snow this week into the upcoming weekend. This runoff will cause rises on local waterways with an increasing threat for localized ice jam flooding...especially across northern NY and central and northern VT rivers. A widespread rainfall on Saturday will produce additional hydro concerns over the weekend for the potential of minor main stem river flooding. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Taber NEAR TERM...Taber SHORT TERM...MV LONG TERM...MV AVIATION...Deal/KGM HYDROLOGY...Taber

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