Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 251804 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 204 PM EDT Sun Sep 25 2016 .SYNOPSIS... Tranquil early fall weather will persist through Monday, as a large area of Canadian high pressure crosses the region. The crisp air mass will allow areas frost to develop once again tonight, with lows generally ranging through the 30s. Developing southerly winds will allow for moderating temperatures on Monday, with high temperatures reaching the mid to upper 60s in most valley locations. A frontal system approaching from the west will bring our next rainfall event Monday night into Tuesday. && .NEAR TERM /THROUGH MONDAY/... As of 204 PM EDT Sunday...It`s another gorgeous early fall afternoon across the North Country with temperatures warming into the mid to upper 50s currently under sunny to mostly sunny skies. Cyclonic flow from a departing trough continues to produce some fair weather cumulus across Northeast Vermont, which will keep temps down a bit in the low/mid 50s for highs, but elsewhere more sunshine is being seen so temps will bump a few degrees from current values to daily highs in the mid 50s to low 60s. For tonight, surface high pressure extending from James Bays southward into the Northeast very slowly drifts eastward, continuing to crest over the region. Any lingering clouds across northeast Vermont will trend towards clear, and with little airmass change from last night and winds aloft lighter, we should see even better radiative cooling conditions than this morning. Despite 925-850mb temps warmer than last night, surface temps area-wide should be a few degrees cooler producing more areal coverage of frost. Have gone ahead and hoisted frost advisories and freeze warnings for just about all of the BTV CWA, excluding Grand Isle County where warmer Lake Champlain waters should keep temps in the upper 30s to low 40s. Elsewhere, lows will widely ranging through the 30s, with some upper 20s possible in the Northeast Kingdom and locally low/mid 20s in the colder hollows of the Northern Adirondacks (i.e. KSLK). In addition, unlike last night where winds aloft mitigated fog development, expect to see some patchy dense fog develop in the usual climo favored river valleys after midnight. On Monday, the aforementioned high shifts off the New England coast allowing winds to shift to the south and temperatures to warm to more seasonal values in the mid to upper 60s. We`ll start the Monday under full sunshine with any morning fog burning off, but as we progress into the afternoon we anticipate some increasing mid and upper level clouds from west as a large closed low approaches. Any rain showers associated with this system should hold off until Monday night though. && .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY/... As of 422 AM EDT Sunday...A cold front will move east from the Great lakes Monday night with rain showers developing over northern New York. Expecting this rain shower activity to move into Vermont mainly after 06Z Tuesday. Have gone with likely or categorical pops. Models showing mid level dry slot to move into the region early Tuesday morning over northern New York, and across Vermont Tuesday morning. Expecting rain shower activity to be over across the region by 18Z Tuesday, as mid level dry slot will be over the region. The only exception to this will be over the Saint Lawrence valley where models hinting at moisture moving northeast from Lake Ontario, so have kept in slight chance pops for showers there. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... As of 422 AM EDT Sunday...Models have a closed upper low over the western Great Lakes Tuesday night, but GFS and ECMWF have vastly different solutions as to the forecast track of this upper closed low through Saturday. This leads to a rather low confidence forecast, especially from Thursday through Saturday. Have gone with a dry forecast across the region Tuesday night through Wednesday night, as GFS and ECMWF in fairly good agreement on this. ECMWF takes this closed upper low over the western Great Lakes and moves it southward to the southern Appalachians and then retrogrades it back to the western Ohio valley by early Friday night, as an upper ridge builds northwest from the Atlantic across New England and northern New York. The GFS model takes this upper low over the western Great Lakes Tuesday night and moves it southeast across the Ohio valley and into southern New England by early Friday night. The ECMWF suggests a mainly dry forecast Thursday and Friday across the region, while the GFS model hints at a showery forecast from Thursday through Saturday. Have opted to stay with the superblend pops from Thursday through Saturday and have low chance pops for showers during this period. Given the significant differences in the location of the closed upper low during the period from the ECMWF and GFS models, forecaster confidence is low through the long term period. && .AVIATION /18Z Sunday THROUGH Friday/... Through 18Z Monday...Mainly VFR conditions are once again expected through the period, with the typical exception being the high likelihood of VLIFR in FG/FZFG at KSLK/KMPV from 05-13Z. North- Northwest winds 8-10 knots with gusts 16-20 knots persist through the daylight hours, then abates to nearly calm overnight. Outlook 18z Monday through Friday... 18z Mon - 00z Tue: Mainly VFR. 00z Tue - 00z Wed: VFR trending to a mix of VFR/MVFR in scattered showers. 00z Wed - 00z Sat: Mainly VFR with isolated MVFR cigs. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...Freeze Warning from 1 AM to 8 AM EDT Monday for VTZ003-004-007- 008-010-017. Frost Advisory from 1 AM to 8 AM EDT Monday for VTZ002-005-006- 009-011-012-016-018-019. NY...Freeze Warning from 1 AM to 8 AM EDT Monday for NYZ026-027- 029>031-034. Frost Advisory from 1 AM to 8 AM EDT Monday for NYZ028-035-087. && $$ SYNOPSIS...Banacos/Lahiff NEAR TERM...Lahiff SHORT TERM...WGH LONG TERM...WGH AVIATION...Lahiff is the U.S. government's official web portal to all federal, state and local government web resources and services.