Area Forecast Discussion
Issued by NWS Burlington, VT

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801 FXUS61 KBTV 232342 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 742 PM EDT Sun Jul 23 2017 .SYNOPSIS... Chances for precipitation increase tonight though as an upper level trough will bring widespread rain to the region late tonight through Tuesday along with much cooler temperatures. The showers will be heavy at times over northern New York. High pressure and warmer temperatures should return by Wednesday however a frontal system will bring showers and thunderstorms on Thursday. && .NEAR TERM /THROUGH MONDAY NIGHT/... As of 219 PM EDT Sunday...Our brief reprieve of calm weather ends this evening as an upper level low over the Great Lakes will bring showers back to the North Country to start the work week. As the upper level low tracks towards the Saint Lawrence valley a series of low pressure systems will bring widespread rainfall to the region. The first of those lows will move into northern New York which happens this evening ushers in thicker cloud cover and enhanced PWAT. Consensus of the guidance brings the PWATs to 1.5-1.6 across the Saint Lawrence valley with 1.2-1.4 across Vermont which is slightly above normal based on the ALY sounding climatology. As the showers increase through the Monday it should be pretty much a washout across the North Country. Temps will be seasonable cold as we`ll be 15 degrees below normal. Concerning the showers, with the above normal PWATs and persistent rainfall, I did keep with the previous forecaster`s idea that the rainfall will be heavy at times. As the first surface low tracks up the Saint Lawrence it should bring a burst of moderate rainfall overnight and then as the upper level low tracks closer the parent low will pivot and begin to dive southeast. This should mean that northern New York receives the most significant rainfall as the energy from the systems will be focused on that area for the longest period of time whereas eastern Vermont will see slightly less total rainfall. Between 1-2 inches will fall over northern New York with between 0.5-1 inch of rain should fall over Vermont. Flooding isn`t currently a concern because RFC flash flood guidance is nearly 2 inches in the 1 hour and between 2-3 in the 3 hour range. There should be enough instability and cold air aloft to support some embedded thunder with the showers mainly over northern New York. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY/... As of 321 PM EDT Sunday...Mid-level trough over the North Country will continue producing showers on Tuesday into Tuesday evening. The trough will be replaced with high pressure Tuesday night with diminishing cloud cover allowing for possible fog development towards early Wednesday morning. At the surface, the ridge of high pressure will crest over the region early Wednesday, then slide off the New England coast during the day. Southwest flow will return, filtering in warmer air. Seasonably cold temperatures on Tuesday with maxes generally in the 60s and mins Tuesday night in the 50s will recover on Wednesday as maxes reach the mid to upper 70s. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... As of 321 PM EDT Sunday...Surface ridge continues to slide into the Atlantic as frontal system approaches the North Country from the northwest on Wednesday night. Expect this boundary to bring showers late Wednesday night through Thursday. At this point, models diverge on sensible weather Thursday night into Friday, but trending to keep precipitation and associated low further south, possibly affecting the southern half of the forecast area. GFS and ECMWF agree on another ridge of high pressure building in from Canada for the weekend. Temperatures throughout the period expected to be near normal. && .AVIATION /00Z MONDAY THROUGH FRIDAY/...
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Through 00Z Tuesday...VFR conditions starting the period are expected to deteriorate as a low pressure system will bring showers to the North Country between 8-10z Monday. Ceilings should be mostly VFR until late in the period when MVFR ceilings will be possible most likely at SLK/MPV. OVC 2500-3000 feet ceilings should move into the region between 13-15z tomorrow expect for PBG where downsloping should keep ceilings as VFR. Showers will start light after 09Z and then become more widespread and heavier with visibility dropping to MVFR and even briefly IFR as heavier showers pass over the region. Slight improvement in intensity of showers and visibility will come very late in the period for eastern TAF sights while western sites will not see improvement until after the end of the period. Winds will be southeast at less than 10 knots during the overnight hours and then 05-10 knots with gusts up to 18 knots Monday afternoon. Outlook... Monday Night: MVFR. Likely SHRA. Tuesday: VFR/MVFR. Chance SHRA. Tuesday Night: VFR. Patchy FG. Wednesday: VFR. NO SIG WX. Wednesday Night: VFR. Slight Chance SHRA. Thursday: VFR. Likely SHRA...Slight Chance TSRA. Thursday Night: VFR. Chance SHRA. Friday: VFR. Chance SHRA.
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&& .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Deal NEAR TERM...Deal SHORT TERM...KGM LONG TERM...KGM AVIATION...Deal/Verasamy

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