Area Forecast Discussion
Issued by NWS Burlington, VT

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385 FXUS61 KBTV 191801 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 201 PM EDT Thu Apr 19 2018 .SYNOPSIS... Low pressure will move over the North Country today leading to widespread light rain and mountain snow. Higher elevation locations will see the potential for 3 to 6 inches of snow with a dusting to an inch possible in the valleys. Temps will remain below normal through the rest of the week before a warming trend begins over the weekend. Coming out of the weekend we should see near normal to slightly above normal temperatures along with dry conditions and plentiful sunshine. && .NEAR TERM /THROUGH FRIDAY/... As of 945 AM EDT Thursday...going forecast in fairly good shape. Blended in the current observations to tweak the next few hours. That system that brought the snow to areas south of here is gone, but it was never really "our" weather maker. It`s the upper trough that is moving into the area. As that trough, which is very well defined on water vapor imagery, moves closer, temperatures aloft will fall. 500mb temperatures currently around -18C will drop to near -23C by late day. Even with the clouds, the strong late April sun will result in some daytime heating, and the combo will produce some instability -- enough for convective showers to develop. Given freezing levels around 1200ft MSL, expect that snowflakes will make it to the surface, even if surface temperatures are in the lower 40s (though at that point they may be mixing with rain). Have blended in some of the latest HRRR and 4km BTV WRF output to show the scattered snow shower development. Just like summer, the higher terrain will be the focus for more of the snow showers. Given the relatively "warm" (above freezing) surface temperatures, not expecting any accumulation below 1000-1200ft elevation this afternoon. Gets a bit interesting overnight. Looks like blocked flow develops within the overall northwest flow. So snowshowers will be most focused on the upslope areas, but the blocked nature could push those snow showers further west of the Green Mountains into the Champlain Valley. Forecast already has this covered, but just mentioning it from what I saw in reviewing data. Not sure about you, but this forecaster is not a huge snow fan to begin with and decidely not a fan of snow (at least at lower elevations) this late into April. At least it melts quickly. Previous discussion follows... An upper level trough will swing through the North Country today with a surface low pressure tracking generally south of the area. By mid morning the upper level trough will move over the region and low level moisture will increase as the flow turns more northwest. This will lead to precip lifting north and becoming scattered across the North Country. The best chance for prolonged precip will be in the mountain areas but all sites should see measurable rain or snow. Snow levels during the day will be in the 1000-1500ft range during the day and then will fall to the valley floors during the evening hours Thursday. So a dusting to an inch of snow will be possible in elevations less than 1000 ft and in the high elevation sites above 2500 feet will have the potential for 3-6 inches of snow with the potential for the Mt Mansfield stake to get close to 100 inches by Friday afternoon. Because we`ll be dominated by the upper level trough through the rest of the week, we`ll continue to be well below normal with highs in the low to mid 40s. Temps overnight will be just below normal with lows in the upper 20s to low 30s. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... As of 352 AM EDT Thursday...A deep-layer trough will be departing to our north and east across the Canadian Maritimes/Newfoundland, with a prevailing NW low-mid level flow in place across the North Country. Should see lingering rain/higher elevation snow showers generally ending during the first half of Friday night (30-40% PoPs early) with decreasing moisture/cyclonic flow. Some partial clearing expected by daybreak Saturday with overnight lows generally in the upper 20s to lower 30s. The weekend generally looks seasonably cool and dry with high pressure across the Great Lakes gradually building eastward. Should see partly sunny conditions with highs in the mid-upr 40s on Saturday, followed by temperatures moderating into the upr 40s to lower 50s with mostly clear conditions and lighter NW winds on Sunday. Precipitation is not expected Saturday or Sunday. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... As of 352 AM EDT Thursday...A deep-layer ridge will build across the northeastern CONUS early next week, finally setting up a warming trend for the region. Should see high temps in the mid-upr 50s for Monday, and into the low-mid 60s for valley locations on Tuesday (normal high for BTV is 57F). Next northern stream shortwave trough expected to arrive on Wednesday per 00Z GFS. Some indication of phasing with a srn stream system from the Carolinas, which would have implications for overall rainfall amts. The 00Z ECMWF has a similar synoptic pattern with possible phasing, though the evolution is about 18-24hrs slower. Too early to say, but a stronger, phased system with better influx of moisture would potentially have implications for moderate to heavy precipitation at the end of the period. We`ll be monitoring this potential. Anticipate high temperatures remaining near 60 degrees for highs on Wednesday. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/...
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Through 18Z Friday...Mix of VFR and MVFR across the region this afternoon. Have scattered snow showers that have developed, and expect these to continue until early afternoon. Possibly very brief periods of IFR, but just like summer t-storms, trying to time when any snow shower affects a particular TAF site is tough. Have used "VCSH" in most TAFs. For BTV, any shower may end up being a rain shower. As we move into the evening, snow showers will become more locked to the higher terrain of the Adirondacks, the Green Mountains and northeast VT. Expecting some of these snow showers to back in from the mountains and affect BTV as well later tonight and early Friday. IFR conditions are expected for that reason at the sites that will be most affected. Snow showers will begin to abate by late Friday morning, with MVFR to VFR conditions across the region. Outlook... Friday Night: Mainly VFR, with local MVFR possible. Slight chance SHSN. Saturday: VFR. NO SIG WX. Saturday Night: VFR. NO SIG WX. Sunday: VFR. NO SIG WX. Sunday Night: VFR. NO SIG WX. Monday: VFR. NO SIG WX. Monday Night: VFR. NO SIG WX. Tuesday: VFR. NO SIG WX.
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&& .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Deal NEAR TERM...Deal/Nash SHORT TERM...Banacos LONG TERM...Banacos AVIATION...Nash

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