Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 201434 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 1034 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/...
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As of 1024 AM EDT Thursday...Rain showers are baring down on Nrn NY. Overall Forecast in good shape with increasing clouds this morning, and steadier precip making its way NE towards the North Country. 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. The HRRR seems to have the best handle on the near term precip for the St Lawrence Valley, so have opted to up the PoPs and QPF slightly to show the hightened band of precip making it`s way north this afternoon. Another concern is the band of precipitation looks to be more narrow and than first thought, which looks like it will focus the precip over the valley and western Dacks. Will look to make more adjustments as the precip moves into the valley. Strong low level deformation associated with front moves into St Lawrence later this afternoon and 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.
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&& .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/... 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. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... 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. && .AVIATION /15Z Thursday THROUGH Monday/... Through 12z Friday...VFR conditions prevail through the rest of the morning. Rain moving into Nrn NY this morning will be light at first. Expect cigs to lower to MVFR in the early afternoon for MSS/SLK and mid-late afternoon for PBG and BTV as rain moves into the area. Rain could be heavy at times, with MVFR/brief IFR possible, especially in the evening hours. Widespread MVFR expected after 00Z/Friday and persisting throughout the overnight. Calm winds will increase with VRB around 5kts this morning, continuing to increase out of the south and 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 12z Friday through Monday... 12z 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/MV 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.