Area Forecast Discussion
Issued by NWS Burlington, VT

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476 FXUS61 KBTV 240217 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 1017 PM EDT Mon Apr 23 2018 .SYNOPSIS... High pressure will continue to provide ideal spring weather to the region with fair skies and seasonably mild temperatures expected through Tuesday. Low pressure lifting out of the Ohio Valley and Mid Atlantic States will bring the next round of showers and a period of steadier rainfall on Wednesday into Thursday. && .NEAR TERM /THROUGH TUESDAY NIGHT/... As of 1016 PM EDT Monday...No changes were needed with this update. Skies remain clear and winds are light to near calm across much of the region. This has allowed temperatures to start to drop; already down to 30F at SLK. Have made some slight adjustments to temperatures to match the current trends, but overall the forecast remains unchanged. Previous discussion...Just an outstanding day unfolding today as deep layer high pressure remains bridged across the northeastern quarter of the nation. Deep layer mixing and full sun has allowed temperatures to climb into the 60s in many locations which has helped erase sore memories of our cold stretch and snow of late late winter/early spring for many. With the ridge in place a persistence forecast will be offered with just some passing high clouds and quiet weather expected through tomorrow. Similar to last night, forecast lows tonight were heavily governed by blended MOS output showing inherent variability during light wind/clear sky nocturnal regimes. In general, values should fall into the upper 20s to mid 30s in the mountains, and from the mid 30s to lower 40s in the St. Lawrence and Champlain Valleys where light south/southwest winds around 5 mph will likely keep the near-surface layer mixed. Highs on Tuesday to be the warmest of the work week - mainly 60s to locally around 70 in mildest locales under light to modest south/southwest return flow as mean 925-850 mb thermal profiles warm by about 2 degrees. By tomorrow night changes will be in the air as southern stream energy across the Tennessee/Lower Ohio Valley lifts northeast and merges with a digging northern stream upper trough approaching from the west. The idea of thickening clouds along with showers/light rain arriving from the south and west later at night or toward morning still looks on track and given consistency in this morning`s model output I`ve largely kept close to our prior forecast in this regard. Lows to remain milder than past nights with continued light south flow and clouds - mainly 40s with a few upper 30s in coldest northern mountain hollows. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY/... As of 326 PM EDT Monday...Wednesday will bring a return of slightly more active weather to the forecast area as a more dynamic pattern replaces the ridging over New England. Energy associated with a shearing northern stream shortwave will dig into the Great Lakes Region Wednesday morning, supporting synoptic scale ascent ahead over the northeastern US ahead of the vort max. At the same time, a cutoff low over the southeastern US will gradually lift northeastward to the Mid- Atlantic Coast Wednesday. Low level southeasterly flow ahead of this cyclone will result in decent Atlantic-moisture advection that will feed into the better dynamics moving in from the west. The individual features will linger over the Northeast through Thursday, then phase and quickly exit to the northeast as a jet carries the strengthening low to the Canadian Maritimes Thursday night. The net result of this setup will be a rainy Wednesday through Thursday afternoon, with showers lingering in higher elevations through Thursday evening. All said and done, it looks like most areas will pick up between a half inch to nine tenths of an inch of rain during this time period. Higher terrain will generally see the most QPF, while the Champlain Valley and Connecticut Valley will see QPF values on the lower end of this spectrum. Daytime high temperatures Wednesday and Thursday will top out in the low to mid 50s, while overnight lows Wednesday night will be moderated by the overcast skies, dropping only into the 40s in most locations. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... As of 326 PM EDT Monday...By Thursday evening, the widespread rain will have ended, with only some lingering showers remaining in higher elevations. Friday will be a nice break in between systems as the now-phased shortwave quickly exits to the northeast and some weak ridging tries to build in. We should get some decent warm air advection Friday as southwesterly flow increases during the day ahead of an upstream digging trough. 925 mb temperatures will climb to 10 to 15 degrees C during the day, and sunny skies will rapidly warm surface temperatures to the mid to upper 60s. Enjoy it while you can however, as clouds will build Friday evening through Friday night ahead of the next disturbance. The weekend will feature a setup similar to the earlier midweek system, with a southern stream upper wave/weak surface low interacting with a more potent northern stream shortwave over the Mid-Atlantic/northeastern US region. The timing/degree of phasing of the systems remains yet to be determined, which could have implications on the more precise timing/location of precipitation. Of higher certainty however is that broad cyclonic flow will exist over the northeastern US Saturday, regardless of whether or not the systems phase, resulting in a fairly wet beginning to the weekend. The good news however, is that the coldest air that has loitered over the northeast for most of the first half of April will be dislodged well to our north over northeastern Canada for the long term, resulting in no foreseeable temperature plunges to finish out the month. Our average highs/lows for this time of year are in the upper 50s/upper 30s, and the longterm pattern suggests that we`ll remain fairly close to climatology through the weekend. Friday will be the warmest day in the longterm, with high temps in the 60s, followed by a slight cool down with highs in the 50s over the weekend. The longwave pattern going into the following week is showing signs of a building Bermuda High to our south, which would provide a warm start to May for us if the pattern pans out. Safe to say spring is here to stay. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... Through 00Z Wednesday...VFR conditions will persist through the next 24 hours with just some passing scattered high cirrus AOA 20,000 ft. Light winds overnight will trend south to southwesterly from 6 to 12 knots with occasional gusts to 20 kts possible at KBTV/KSLK/KMSS after 13z Tuesday. Only real concern is some occasional southwesterly LLWS to 35kt at KMSS terminal in the 06-12Z time frame as stronger flow aloft pushes into the region. Outlook... Tuesday Night: VFR. Likely RA, Chance SHRA. Wednesday: Mainly MVFR, with local IFR possible. Definite RA. Wednesday Night: MVFR. Likely RA. Thursday: Mainly MVFR, with local IFR possible. Likely SHRA. Thursday Night: Mainly VFR, with local MVFR possible. Chance SHRA. Friday: VFR. Slight chance SHRA. Friday Night: Mainly VFR, with local MVFR possible. Chance SHRA. Saturday: Mainly VFR, with local MVFR possible. Chance SHRA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...JMG NEAR TERM...Hastings/JMG SHORT TERM...RSD LONG TERM...RSD AVIATION...Hastings/JMG

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