Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 220735 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 335 AM EDT Tue May 22 2018 .SYNOPSIS...
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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.
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&& .NEAR TERM /THROUGH WEDNESDAY/...
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As of 335 AM EDT Tuesday...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 338 PM EDT Monday...No real big changes from the previous forecast thinking for the middle to end of the work week with models remaining very consistent. Overall big picture highlights an upper trough with some modest shortwave energy tracking through ME/NH skirting our northeast zones on Wednesday, followed by high pressure for Thursday and Friday. Outside of a few showers and perhaps an isolated thunderstorms across northern areas Wednesday, the rest of the week will be dry with temps ranging through the 70s on Wednesday, cooler in the upper 60s to low 70s for Thursday, and significantly warmer in the upper 70s to low 80s on Friday. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... As of 338 PM EDT Monday..Still a ton of uncertainty for the holiday weekend with little model run to run consistency. Latest GFS and Canadian GEM show a frontal zone and digging upper trough over central Quebec dropping southward into the Northeast Friday night through Saturday, with an upper level ridge and surface high pressure building in for Sunday and Monday. This is in stark contrast to previous runs, while the ECMWF has remained more consistent showing the trough well farther northeast over the Canadian maritimes. The ECMWF still highlights a frontal zone moving over the region Friday night into Saturday, but without the trough to kick it out, wetter and warmer conditions prevail through the weekend. Moderate forecast confidence at this point that we`ll see some rainfall Friday night into Saturday, but beyond that confidence is very low. Stay tuned. && .AVIATION /08Z TUESDAY THROUGH SATURDAY/... Through 06Z 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 20-23Z time frame onward. Winds light and generally less than 10 kts through the period. 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. NO SIG WX. Friday Night: VFR. Chance SHRA. Saturday: Mainly MVFR, with local IFR possible. Chance SHRA. && .MARINE...
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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.
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&& .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...JMG NEAR TERM...JMG SHORT TERM...Lahiff LONG TERM...Lahiff AVIATION...JMG MARINE...JMG

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