Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 190030 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 730 PM EST Sun Feb 18 2018 .SYNOPSIS... Dry conditions continue overnight with ridge of surface high pressure building over the area. A significant warming trend is expected Monday through Wednesday of this week, along with periods of rain. Record high temperatures are possible Tuesday and Wednesday, with highs well into the 50s and possibly lower 60s. A flood watch is in effect. && .NEAR TERM /THROUGH MONDAY NIGHT/...
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As of 729 PM EST Sunday...High pressure will remain over the region tonight, before sliding eastward on Monday. Clouds will increase overnight with mid-high clouds moving into our area from west to east. Low temperatures will be mild overnight with increasing southerly return flow and plenty of clouds across the region. Low temperatures will only drop into the upper teens to mid 20s. High clouds exit the region to our east Monday morning with sunny skies developing by mid-morning and temperatures warming well above normal into the 40s areawide. This is in response to the aforementioned high shifting offshore and a warm southerly return flow developing in advance of a warm front lifting northward from the Ohio and Tennessee Valleys through the day. Most of the day will remain dry, but chances for showers increase during the late afternoon into evening hours, especially across northern New York where rain looks to move in around the evening rush hour. The rain will initially be pretty spotty and showery in nature. Overnight Monday into Tuesday chances for precipitation will increase as a surface boundary stalled out to our North will be focus for several low pressure areas to pass through. Cold front will sink towards our forecast area Monday night, and best chance for rain will be along the international border, especially in the Saint Lawrence Valley in Northern New York. Our region will remain in the warm sector, with minimum temperatures only dipping to the mid 30s to around 40. Precipitation will mainly be in the form of rain with only a small chance of freezing rain and light icing in some of the colder valleys of Eastern Vermont where some cold air tends to linger the longest, though not expecting a lot of rainfall there initially anyway.
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&& .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... As of 420 PM EST Sunday...The concern for this period will be the flooding potential. See the hydrology section below for details. The warm front will remain poised to our north Tuesday and Tuesday night with waves of low pressure traversing along the boundary. Moisture will increase through the day Tuesday as PWATs approach 1.50 inches. These factors will result in periods of rain through the period, with the steadiest precipitation falling over far northern VT, the northern Adirondacks, and the Saint Lawrence Valley. Temperatures will be quite mild Tuesday, in the lower to mid 50s for most, but still a bit short of daily record highs. Dewpoints will rise through the 40s, exacerbating snowmelt from the warm temperatures. After a brief drop in the evening, temperatures may actually rise back into the mid 50s overnight Tuesday night, particularly for areas west of the Greens. As such, record warm low temperatures may be set; these data are included in the Climate section below. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... As of 420 PM EST Sunday...Very mild conditions expected on Wednesday as temperatures sky rocket into the upper 50s to lower 60s. Some locations in the southern Champlain Valley and lower Connecticut River valley could actually approach 70, especially if they see any breaks in the cloud cover. Daily record highs will be threatened in many locations; see the Climate section below. The warm front will begin to slowly move south as a cold front late in the day, slowly shifting the rain back toward central portions of our forecast area. There are still some timing differences in exactly when the front will make its southward push, but cooler and drier air will follow in its wake, bringing an end to the rain, perhaps changing to snow late. Did note that the GFS is slower with the frontal passage, which would extend the precipitation into Thursday morning. Rainfall amounts through Wednesday evening will mainly be in the 0.50 to 1.50 inch range across the northern areas of our forecast area, while central and southern Vermont will get less than a half inch. Runoff from snowmelt and rainfall will continue through at least part of the night, so area waterways will need to be watched even once temperatures drop back below freezing. For Thursday through Sunday...looking cooler and fairly active as the northeastern CONUS remains under fast zonal flow with low pressure systems progged to move through every day or two. While temperatures will be cooler than what we`ll see in the middle of the week, they`ll still be above normal, generally in the mid 30s to mid 40s during the day, overnight lows in the teens and 20s. There`s little model agreement on whether precipitation will fall as rain or have stayed close to a model blend on temperatures which resulted in a lot of rain/snow mix through the end of the week. && .AVIATION /01Z MONDAY THROUGH FRIDAY/... Through 00Z Tuesday...High pressure cresting over the region overnight will keep TAFs VFR and winds light through the morning hours. There are some patchy mid level clouds lingering over the northern Adirondacks and areas of Vermont, however expect these to decrease by the early morning hours as drier air works its way down under the building high. By 12Z however, cloud cover will start to thicken and increase through the day in advance of an approaching system from the southwest. By 21Z, VFR conditions will deteriorate to MVFR and IFR as rain starts to spread over the region. Light winds overnight will become gusty from the southwest during the daytime hours tomorrow. A low-level jet overhead will result in some LLWS at SLK between 11Z and 14Z. Outlook... Monday Night: Mainly MVFR, with local IFR possible. Chance RA, Definite FZRA. Tuesday: Mainly MVFR, with areas IFR possible. Definite RA. Tuesday Night: Mainly MVFR, with local IFR possible. Chance RA. Wednesday: Mainly MVFR, with local VFR possible. Chance RA. Wednesday Night: Mainly MVFR, with local IFR possible. Chance SHRA, Chance SHSN. Thursday: Mainly VFR, with areas MVFR possible. Slight chance SHSN. Thursday Night: VFR. NO SIG WX. Friday: VFR. Slight chance SHRA, Slight chance SHSN. && .HYDROLOGY... As of 420 PM EST Sunday...A 48-hour period of anomalously warm temperatures will affect the region from Monday through Wednesday afternoon. Periods of rainfall, modest winds and dewpoint temperatures climbing into the 40s to lower 50s will foster rapid snowmelt and ice break-up across the entire area. Also boosting confidence are extremely high thawing degree hour totals - averaging 900 to 1200 over the Tuesday/Wednesday time frame. The model consensus continues to show totals to average from 0.5 to 1.5 inches across far northern VT into the northern Adirondacks and SLV. Lesser amounts generally under a half an inch are expected across central and southern VT. Taking this all into account, modest to substantial river rises look highly probable starting Monday night and continuing into Wednesday, supported by NAEFS/SREF MMEFS hydrograph data. While widespread open water flooding is not expected, several rivers may approach minor flood. With numerous ice jams in place from the substantial thaw this past January, localized high water/flood concerns near these features remains a real concern as ice break-up occurs. && .CLIMATE... Here are the current record high temperatures for February 20th and 21st: Record High Temperatures: ............Feb 20th....Feb 21st.... BTV.............58 (1981)...59 (1981)... MPV.............56 (1994)...57 (1953)... MSS.............63 (1994)...62 (1953)... St. Johnsbury...60 (1981)...62 (1981)... Record High-Minimum Temperatures: ............Feb 20th....Feb 21st.... BTV.............50 (1981)...49 (1981)... MPV.............47 (1981)...47 (1981)... MSS.............47 (1994)...41 (1981)... St. Johnsbury...40 (1981)...46 (1981)... && .BTV WATCHES/WARNINGS/ADVISORIES... VT...Flood Watch from late Monday night through Wednesday evening for VTZ001>012-016>019. NY...Flood Watch from late Monday night through Wednesday evening for NYZ026>031-034-035-087. && $$ SYNOPSIS...Neiles NEAR TERM...Banacos/Neiles SHORT TERM...Hastings LONG TERM...Hastings AVIATION...RSD HYDROLOGY...Hastings CLIMATE...TEAM BTV is the U.S. government's official web portal to all federal, state and local government web resources and services.