Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 221135 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 735 AM EDT Tue May 22 2018 .SYNOPSIS... Cloudy skies and periods of showers are expected today into this evening as weak low pressure crosses the region. A cold front will cross the area by Wednesday afternoon with little fanfare other than a few showers or perhaps an isolated storm across northern counties. Behind this front fair and seasonably warm weather is expected through the remainder of the work week. && .NEAR TERM /THROUGH WEDNESDAY/...
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As of 735 AM EDT Tuesday...The current forecast remains on track as we progress toward mid-morning. Scattered to numerous showers to advect into the forecast area later this morning, and especially this afternoon with best coverage generally across central/southern counties. Have a great day. Prior discussion... Kind of a "meh" day on tap for our area as we continue to watch weak low pressure and associated moisture streak east/northeast from the eastern Great Lakes and Ohio Valley this morning. While we`ll maintain higher chance to likely pops across our area by this afternoon, several factors argue for a low impact event with generally light QPF expected. These are namely 1) a fairly dry boundary layer through early afternoon, 2) anticyclonic, confluent flow aloft, and 3) a general lack of large-scale forcing for upward vertical motions. As such, while aforementioned pops will top out in the 50-70% range this afternoon and early evening our latest QPF has been reduced significantly, in some cases by as much as 50% from prior forecasts. This suggests 18-hr totals ending by midnight or so to generally range from a tenth to one quarter inch with locally lighter totals in portions of the broader valleys. Any thunder threat will remain well south of our area. Highs today will be significantly cooler than yesterday given widespread cloud cover and shower activity - mainly 60s under light south to southwesterly flow. Scattered to numerous evening showers then gradually shift east and end overnight as surface high pressure noses into the area. Skies will trend partly cloudy over time, especially north and west as low temperatures range from 46 to 54 or so. Some patchy fog will also be possible, mainly in the Adirondacks. By Wednesday a well advertised cold front will drop southward through the region as flow veers from southerly to north/northwesterly by afternoon. As mentioned last night, we`ll be on the back side of this front and parent upper trough with better moisture and attendant forcing generally lying off to our northeast. This morning`s 00Z guidance still advertises a lower end threat for a few showers across far northern counties, especially northern VT by later in the morning and afternoon as the front passes through with southern counties remaining largely dry. Low level lapse rates will remain quite steep with a mid level instability layer developing between 850 and about 600 mb where a weak capping layer will likely take shape. Whether any updrafts can become robust enough to generate in-cloud graupel and thunder remains in question. However, given modest convergence along the boundary, lower-end CAPE values of a few hundred J/Kg and blended MOS thunder progs from 10- 18% I`ll maintain an isolated storm threat across mainly northeastern VT counties accordingly. High temperatures will trend warmer once again due to higher coverage of partial sunshine - mainly 70s.
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&& .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... As of 335 AM EDT Tuesday...The end of the work week will be relatively quiet with no active weather expected. Broad high pressure with anticyclonic flow is expected both Thursday and Friday. The northwesterly winds behind a front on Wednesday will usher in slightly cooler temps so expected highs on Thursday in the upper 60s to low 70s but by Friday morning southerly flow sets up and we`ll see warming temperatures with highs on Friday in the upper 70s to low 80s under partly cloudy skies. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... As of 335 AM EDT Tuesday...As we head into the weekend the prognosis is getting clearer that Saturday will likely be the wetter of the two days. There`s still some discontinuity between the guidance suite but the general idea is that an upper level trough over the Maritimes will drag a frontal system through the North Country. The question is how far south does the boundary go. The GFS stalls the boundary over southern New England while the EC stalls the system along the international border. I`ve leaned with a blend of the new guidance along with much of the previous forecast to trend the chances for rain a little bit lighter on Sunday afternoon and evening as there`s some idea of weak ridging building in. With the continued varying solutions we`ll continue to monitor but confidence isn`t super high one way or another. Coming out of the weekend its much of the same in that models are all over the place largely based on how they handle the system moving in over the weekend. With the GFS dry and the EC wet I`ve offered the idea of slight chance to change pops and will adjust accordingly with newer guidance. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/...
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Through 12Z Wednesday...VFR through 18Z, then deteriorating conditions thereafter as areas of showers push into the region with approach of weak low pressure and associated moisture from the Great Lakes. During this period conditions lower to MVFR with patchy IFR in favored locales, especially from the 20-01Z time frame onward. Winds light and generally less than 10 kts through the period. Some indications of partial clearing late in the forecast period, but enough uncertainty to warrant omission at this point. Outlook... Wednesday: VFR. Slight chance SHRA, Slight chance TSRA. Wednesday Night: VFR. NO SIG WX. Thursday: VFR. NO SIG WX. Thursday Night: VFR. NO SIG WX. Friday: VFR. Slight chance SHRA. Friday Night: VFR. Chance SHRA. Saturday: Mainly MVFR, with local IFR possible. Chance SHRA.
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&& .MARINE... As of 335 AM EDT Tuesday...A Lake Wind Advisory is in effect for today, with the main period of stronger winds occurring this afternoon and early evening. During this period southerly winds will average from 15 to 25 kts with occasional gusts to near 30 kts on portions of the broad lake from the Charlotte Ferry crossing northward. Bays and inlets with southerly exposures will also see enhanced winds with a light chop expected. These conditions could prove hazardous to inexperienced mariners, especially those with small craft such as kayaks and canoes. The southerly winds will abate later this evening. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...JMG NEAR TERM...JMG SHORT TERM...Deal LONG TERM...Deal AVIATION...JMG MARINE...JMG

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