Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 200934 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 534 AM EDT Thu Oct 20 2016 .SYNOPSIS... Strengthening surface low pressure system will bring widespread rain to the North Country Thursday afternoon through Sunday. Occasionally heavy rainfall expected, especially this evening into early Friday. As the front pushes east of the area by early next week a return to seasonably cooler weather is expected. && .NEAR TERM /THROUGH FRIDAY/... As of 510 AM EDT Thursday...Today looks to be the beginning of a pattern change as 500mb trough continues to dig south and gradually east over the central USA. Rain will encroach upon the St Lawrence Valley and Adirondacks in the early afternoon associated with frontal system moving in from the SW. Question remains how far north and east it will spread before the deepening trough and surface low riding up the frontal boundary causes area of rain to pivot north and west sometime on Friday. Strong low level deformation associated with front moves into St Lawrence this afternoon into tonight, leading to heavier rainfall for Nrn NY, before weakening on Friday. Another consideration for Friday is sub-tropical system weakening as it heads north far off the Carolina coast, but moisture looks to get absorbed or wrapped into the low affecting the Northeast, and could result in resurgence of heavier precip over eastern VT late Friday into Friday night, per the 00Z ECMWF. This may be dependent on when the 500mb trough becomes more neutral or negatively tilted late Friday. Winds another concern as strong low level jet enters the region this afternoon. Southerly jet of 40-55kts at 850mb stays over the North Country through Friday. This will lead to strong winds across the higher terrain. Best chances for strong winds to mix into the valleys would be early Friday as the precip shield pivots slightly NW, allowing for breaks in precip over VT. Have gusts up to 15-25kts across most of the area on Friday, before the surface low tracks over the area. In summary, cloudy and wet pattern expected throughout the near term with temperatures in the mid 50s to mid 60s today as we remain in the warm sector. Tonight temperatures remain mild in the mid 40s to upper 50s. Forecast max temperatures tricky on Friday as the surface low and associated front traverse across the North Country. Timing of FROPA will dictate wind shift of NW-N and colder air filtering in. && .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
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As of 534 AM EDT Thursday...Models in good agreement with bringing abundant moisture into the north country through the period. Have gone with categorical pops for Friday night and Saturday. Expecting precipitation to become more showery Saturday night, as surface low pressure area moves north into Quebec Saturday night. Models showing a closed upper low will move into the region late Saturday and Saturday night which will produce dynamical cooling aloft, so expecting rain to change to snow over the higher elevations of the Adirondacks and Green Mountains late Saturday into Saturday night. Some locally heavy snow is possible over the higher summits of the Adirondacks and Green Mountains Saturday night.
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As of 534 AM EDT Thursday...Expecting rainfall amounts from Thursday through Sunday to be around 2 to 4 inches across the north country. Some locally heavy snowfall is possible Sunday over the higher summits of the Adirondacks and Green Mountains on Sunday. The region will remain under cyclonic flow from the surface low pressure area over eastern Canada Sunday through Monday night, so have chance pops for rain and snow shower in the forecast. A high pressure area over the western Great Lakes on Tuesday will build slowly east and bring mainly fair and dry weather to the north country Tuesday night and Wednesday.
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&& .AVIATION /09Z Thursday THROUGH Monday/... Through 06z Friday...VFR conditions except at KSLK with IFR to VLIFR possible this morning. MPV could see brief period of LIFR/VLIFR centered around 10Z. In the late morning ceilings lower to around 4000-5000 feet as a front will bring rain showers to most terminals. Expect rain to affect MSS/SLK/PBG/BTV by early afternoon. Possible periods of MVFR with confidence of MVFR cigs and vsbys at MSS/SLK around 19Z onward. PBG/BTV/MPV could see MVFR conditions after 00Z Friday. Winds vary greatly due to proximity to front. Overall expect southerly winds, possibly gusting at times in the afternoon as low level jet moves over the North Country late this afternoon into evening. Cannot rule out possible LLWS, especially heading into the overnight. Outlook 06z Friday through Monday... 06z Friday through 00z Monday: A prolonged period of unsettled conditions is expected with widespread MVFR/IFR in periods of rain. 00z Monday through 00z Tuesday: A mix of VFR/MVFR...with VFR/IFR possible in showers. && .HYDROLOGY... As of 510 AM EDT Thursday...A widespread and long duration rainfall of 2 to 4 inches with isolated higher amounts expected to start midday Thursday and ending Sunday. There will be some breaks throughout the event, especially across portions of Vermont. Given most of the region is in moderate to severe drought...we are not anticipating any widespread hydro issues. However...some minor urban and street flooding is possible associated with the heavier rainfall rates on Friday with leaves clogging storm drains. Otherwise...some modest rises in local rivers and streams are likely this weekend...but no widespread flooding is anticipated. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Lahiff/KGM NEAR TERM...KGM SHORT TERM...WGH LONG TERM...WGH AVIATION...KGM HYDROLOGY...Taber/KGM is the U.S. government's official web portal to all federal, state and local government web resources and services.