Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 212347 AFDBTV AREA FORECAST DISCUSSION National Weather Service Burlington VT 647 PM EST Thu Feb 21 2019 .SYNOPSIS... Gusty westerly winds will shift to the northwest late this afternoon before weakening after midnight night. While a few showers are possible through the afternoon and evening hours, the areal coverage will diminish as large scale high pressure builds into the region on Friday. Expect more seasonable temperatures Friday and Saturday with highs in the 30s and lows in the mid teens to mid 20s. The next chance of precipitation comes late Saturday night and Sunday where a mix of snow, freezing rain and sleet will be possible before changing over to all rain during the afternoon hours on Sunday. Strong and gusty southwesterly winds ranging from 25 to 40 mph will develop on Sunday as a surface low tracks to our west. Much colder air will move into the North Country on Monday and Tuesday with the return of below normal temperatures to start the upcoming work week. && .NEAR TERM /THROUGH FRIDAY NIGHT/... As of 643 PM EST Thursday...Overall forecast is in good shape this evening based on observations and radar trends. Have continued to mention chc pops across the northern Dacks into the mountains of central/northern VT. However, depth of moisture is limited along with forcing, so any accumulation will be light. MRMS radar data continues to show some activity upstream across southern Canada, which will rotate into our northern mountains overnight, especially as 925mb to 850mb winds becoming more northwest in direction. These changing winds will help to enhance modest low level caa, as temps atop Whiteface are now in the upper teens. Lows generally in the teens mountains sites to mid 20s warmer valleys. Updated to capture latest obs, otherwise forecast in good shape. Previous discuss below: A few breaks in the clouds have begun to develop across the Champlain Valley this afternoon but these breaks are few and far between. Nevertheless, temperatures have finally warmed into the 40s in response to increased insolation. Looking at observations across the forecast area, the strongest winds currently reside in the Champlain Valley which is attributed to the warmer temperatures at the surface. The warmer surface temps have steepened low level lapse rates as temperatures aloft begin to cool. This has helped and will continue to help mix stronger winds down to the surface through the afternoon hours. The gusty winds will likely continue through at least midnight and possibly a few hours thereafter. With the continued cold air advection, the low level lapse rates will remain steep enough to mix winds down from between 3500 and 5000 ft. The core of strong winds in the mixed layer will shift eastward through the overnight hours and by Friday morning winds will generally be 10 mph or less. There are still a few snow/rain showers residing across northern New York and northern Vermont this afternoon with a weak deformation zone situated across the region. Thanks to the dry-slot that developed this morning, moisture has been lacking with has reduced both areal coverage and intensity of any linger shower activity. This deformation zone will dissipate after midnight with synoptic scale ridging building across the region heading into Friday. In addition, surface high pressure will be centered across the North Country Friday afternoon which will reduce precipitation chances to zero come Friday. Temperatures will be more seasonable Friday with highs in the 30s and lows in the mid teens to mid 20s. && .SHORT TERM /SATURDAY THROUGH MONDAY/... As of 345 PM EST Thursday...Expect a quiet start to the weekend as broad high pressure crests over the region. The nice weather will come to an end during the overnight hours Saturday as the high departs to the east. A deepening low pressure system will be digging into the Great Lakes region Saturday evening lifting a warm front and precipitation along with it late Saturday night into Sunday morning. Southerly warm air advection should bring a warm nose into Northern New York leading to some periods of some mixed precipitation overnight before transitioning to all rain by mid morning. Across Vermont it will be a different story as we`ll have to wait and see how strong the coastal low develops. The NAM really deepens that secondary low and forced colder air in east of the Greens which will hold on to some wintry precip well into the afternoon hours. I choose to offer a solution sort of in between because the NAM is an outlier with regards to the thermal profiles but I do agree with slightly colder temperatures being more likely across eastern Vermont where its notoriously hard to scour out cold temps. The general consensus of medium ranged models is that the warm nose should be somewhere between +2 to +4 and thats plenty enough to melt any ice crystals aloft. By the afternoon/early evening its a moot point as we`ll be sitting solidly in the warm sector of the low pressure system and everywhere should see rain. The amount of precip will heavily depend on a strong southwesterly jet which will lead to shadowing across portions of the Champlain Valley. That strong low level jet will also be the forcing for some blustery winds across the Saint Lawrence Valley Sunday and then across the rest of the North Country Sunday night into Monday. Wind gusts based off the latest round of guidance should solidly be in the 35- 40 mph range with a few gusts up to 45 possible. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... As of 345 PM EST Thursday...The work week should be relatively quiet with a few weak impulses that pass through under broad upper level cyclonic flow. Based on latest trends we should have a couple of seasonable cool days to start with temperatures pushing back to near normal by the middle of the week. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... Through 00Z Saturday...Flight conditions are currently VFR at all TAF sites, except SLK. A weak boundary moving south will cause ceilings to lower from 04Z to 09Z with KMPV, KRUT, and KSLK seeing ceilings fall to 1500-2500ft agl. Elsewhere, scattered cover at 2500ft agl is indicated. Light showers will follow the boundary south, but none appear likely to impact TAF sites at this time. Winds will be out of the west-northwest with a few sites becoming more northwesterly after 04Z. Wind speeds and gusts will be gradually diminishing with higher gusts ceasing about 09Z. Wind speeds should settle around 5 to 10 knots. After 09Z, ceilings will begin to lift again with all sites VFR, except at SLK, where ceilings will remain MVFR until mid-day around 19Z. Outlook... Friday Night: VFR. NO SIG WX. Saturday: VFR. NO SIG WX. Saturday Night: Mainly VFR, with local MVFR possible. Chance SN, Likely FZRA, Likely PL. Sunday: Mainly MVFR, with local VFR possible. Windy with gusts to 30 kt. Definite RA, Definite FZRA. Sunday Night: Mainly VFR, with areas MVFR and IFR possible. Windy with gusts to 35 kt. Likely SHSN, Likely SHRA. Monday: VFR. Windy with gusts to 35 kt. Chance SHSN. Monday Night: VFR. Slight chance SHSN. Tuesday: VFR. NO SIG WX. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Clay NEAR TERM...Clay/Taber SHORT TERM...Deal LONG TERM...Deal AVIATION...Haynes

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