Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 180721 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 321 AM EDT Tue Jul 18 2017 .SYNOPSIS... A ridge of high pressure will bring warmer and drier conditions to the area today and tomorrow before another frontal system moves in on Thursday and Friday with a chance of showers and thunderstorms. A little bit cooler and drier weather are likely by Saturday under high pressure from Canada. && .NEAR TERM /THROUGH WEDNESDAY/... As of 233 AM EDT Tuesday...Areas of fog after yesterdays rain will be burning off this morning as weak high pressure moves into the region and gives us a decent day today. The upper level trof is moving out with warm advection aloft but can`t quite rule out an isolated shower with CAPE values between 250-500 J/kg especially far NE VT under exiting trof axis. 850 temps of 14C will bring temps into the 80s across our forecast area. Tonight should be mostly clear under weak high pressure centered a bit to our south, short wave ridging aloft, and low PWs less than 0.75". Northern St. Lawrence and Champlain valleys will hold onto a weak pressure gradient favoring a bit of a SW and S flow overnight, elsewhere calm or light variable winds will allow for dense river valley fog to form as is typical for this time of year as we enter the time of year with the highest frequency of occurrence for radiational fog. A weak westerly flow on Wed with mostly sunny skies and 850 temps up to 16C will again bring temps into the 80s perhaps topping out around 88 at BTV. A weak cold front moving through Ontario late in the day will bring about a bit of an increase in CAPE (near 500-750 J/kg), PW (1.50"), and clouds in the St. Lawrence Valley late in the day, so just a slight chance of a shower or thunderstorm there. && .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/... As of 321 AM EDT Tuesday...Overall Wednesday night and Thursday looking pretty good with weak high pressure over the area. Any convection near the Canadian Border Wednesday night should dissipate as the night wears on with the loss of instability. Highs on Thursday will be in the low to mid 80s and dew points in the 60 to 65 degree range. These conditions should be sufficient to produce instability Thursday afternoon and forcing from the mountains should be able to produce some showers and possibly a thunderstorm. Parameters for organized storms do not look like they will be a factor. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... As of 321 AM EDT Tuesday...Northwest flow aloft develops over the area Thursday night into Friday and it looks like a front will move down over our area and enhance the potential for showers and storms. This may be the best day with respect to areal coverage of the convection. Thermal boundary becomes established just to our south over the weekend as the flow aloft remains from the west and northwest. A series of shortwaves will move through the flow and continue to enhance the potential for some showers or storms. Unfortunately longer range data has not had any consistency with respect to timing of these features and best approach at this time will be to mention a chance of showers or storms over the weekend and early next week. High temperatures will be trending down toward seasonal normals and maybe even slightly below normal by early next week. && .AVIATION /07Z TUESDAY THROUGH SATURDAY/... Through 06z Wednesday...VLIFR fog at KSLK and KMPV, IFR expected at KPBG, with possible MVFR at KMSS and KRUT until 12-13Z. VFR will return aft 13z persist throughout the day. At KBTV VAD wind shows low level winds of 15-20 knots and should keep boundary layer mixed throughout most of the night preventing fog development. Expecting SCT cumulus development by late morning and dissipating by sunset. Fog developing again late tonight at KSLK with KMPV following aft 06z. Winds generally calm/light variable becoming south to southwest at 5 to 10 knots during the day then calm again after sunset tonight. Outlook... Wednesday: VFR. Slight Chance SHRA...Slight Chance TSRA. Wednesday Night: VFR. Slight Chance SHRA...Slight Chance TSRA. Thursday: VFR. Chance SHRA...Slight Chance TSRA. Thursday Night: VFR. Slight Chance SHRA. Friday: VFR. Chance SHRA...Chance TSRA. Friday Night: VFR. Slight Chance SHRA. Saturday: VFR. NO SIG WX. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Sisson NEAR TERM...Sisson SHORT TERM...Evenson LONG TERM...Evenson AVIATION...Sisson

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