Area Forecast Discussion
Issued by NWS Burlington, VT

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548 FXUS61 KBTV 240529 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 129 AM EDT Tue Oct 24 2017 .SYNOPSIS... A deep trough of low pressure over the Ohio Valley this evening will shift into the Great Lakes tonight and Tuesday providing the North Country with a windy and wet Tuesday and Tuesday night. The rain will end from west to east during the early morning hours on Wednesday, with total rainfall in the 1 to 2 inch range over much of the area. && .NEAR TERM /THROUGH TONIGHT/...
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As of 129 AM EDT Tuesday...Overall forecast in good shape with just a few tweaks to match the current conditions. Otherwise will mainly see clouds increase...winds increasing...and eventually precipitation chances increasing through the early morning hours which is covered nicely in the going forecast. Previous Discussion... Big picture highlights strong high pressure anchored off the eastern seaboard while a deep upper trough is digging into the Ohio Valley this afternoon. As the low strengthens and shifts north/northwestward into the Great Lakes, the attending frontal boundary will tap into sub-tropical moisture from the Gulf of Mexico, readily seen on today`s blended TPW products. Some of this deeper moisture is already working into the region this afternoon with surface dewpoints rising into the mid 50s, and a low marine stratus layer working up the southern Champlain and Connecticut River valleys. As the front tracks through the region late tonight through Tuesday, the deep moisture combined with strong surface to mid-level winds paralleling the front will develop a band of moderate to locally heavy rain moving over northern New York during the morning hours, and Vermont in the afternoon and evening. Ahead of the front, winds will continue to become increasingly gusty with the mean 925mb flow from the south/southeast strengthening to 40-50kts. With a more southerly component to the direction versus southeast, true downslope effects won`t be realized despite gusts in the 30-40mph range. The wind combined with falling leaves could present an issue with clogged drains in urban areas, especially considering QPF should be fairly widespread in the 1-2" range. Rivers should be able to handle the QPF, so don`t think we`ll have any concerns there.
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&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY/... As of 350 PM EDT Monday...Models continue to show the back edge of precipitation associated with cold front exiting central and eastern VT on Wednesday. With the 500mb trough lagging behind flow will generally be parallel to the front, making for a more gradual end to rain showers across central and eastern VT. SW flow behind the front could also filter in moist air and clouds from Lake Ontario with just a slight to low chance of some showers over the Adirondacks into the Champlain Valley late Wednesday into Wednesday night. The aforementioned 500mb trough looks to swing through the area sometime Thursday, keeping chance of showers over the North Country. Temperatures running 5-10 degrees above normal Wednesday and Wednesday night will cool to near to slight above normal on Thursday. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... As of 350 PM EDT Monday...12Z ECMWF is slower to progress the 500mb trough eastward, keeping chance of showers over eastern portions of the North Country Thursday night, while the GFS shows slight ridging and PWATs falling to less than half an inch. Friday looks to be dry with increasing southerly flow ahead of another system approaching from the west. Models diverge on evolution of this system and its upper level support as we head into the weekend. At this point in time, Saturday looks to be mostly dry with a longwave trough digging south and east into the western Great Lakes region Saturday night. Potential development of a coastal closed low at the surface Sunday could bring warm moist air into the Northeast Sunday into Monday. Chance of showers continues into Monday night. Above normal temperatures are expected throughout the period. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... Through 00Z Wednesday...VFR conditions will continue overall across the region through 12Z Tuesday, with the exception being KMPV where marine MVFR stratus advecting northward will build into eastern Vermont after 06Z. Elsewhere, expanding cirrus deck will just gradually lower through the night. After 12Z, low clouds shift into portions of northern New York, mainly affecting KPBG while rain shifts over KMSS and KSLK and gradually shifts eastward reaching KPBG/KBTV/KRUT after 17Z. Rain will be heavy at times with visibility decreasing to MVFR conditions at times. Winds will continue to be increasingly gusty from the south/southeasterly in the 15-25kt range through 12Z, strengthening to 25-40kts east of KMSS thereafter. Outlook... Tuesday Night: VFR. Windy with gusts to 30 kts. Definite RA...Chance SHRA. Wednesday: VFR. Chance SHRA. Wednesday Night: VFR. Chance SHRA. Thursday: VFR. Chance SHRA. Thursday Night: VFR. Slight Chance SHRA. Friday: VFR. NO SIG WX. Friday Night: VFR. NO SIG WX. Saturday: VFR. Slight Chance SHRA. && .MARINE... A lake wind advisory is in effect through at least Tuesday. Winds will be from the south at 15 to 30 knots tonight, but increase into the 25 to 35 knot range on Tuesday. Winds of this magnitude will create rather choppy conditions, especially on the northern portions of the lake, and waves will build into the 4 to 6 foot range by Tuesday. && .EQUIPMENT... MPV is not transmitting due to a communications outage. FAA is aware of the problem. We do not have an estimated return to service. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Lahiff NEAR TERM...Evenson/Lahiff SHORT TERM...KGM LONG TERM...KGM AVIATION...Lahiff/Verasamy MARINE...Evenson EQUIPMENT...BTV

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