Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 210800 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 400 AM EDT Fri Oct 21 2016 .SYNOPSIS... Strengthening surface low pressure system has started bringing widespread rain to the North Country and will continue to do so through Sunday. Occasionally heavy rainfall is expected across the Saint Lawrence Valley and Northern Adirondacks through Friday. As the front pushes east of the area by early next week a return to drier weather and seasonably cooler temperatures is expected. && .NEAR TERM /THROUGH SATURDAY/... As of 203 AM EDT Friday...Rain over Nrn NY continues with most of VT remaining dry outside of NW VT. Breaks in the Champlain valley as water vapor hits development of baroclinic leaf around wrn Ohio. This will likely result in area of rain pivoting more westward over the North Country...keeping St Lawrence and Adirondacks in the rain through Friday afternoon. Previous discussion...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 are also 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 will be very 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, especially through the valleys and lower terrain. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
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As of 400 AM EDT Friday...Rain will gradually change to snow over the higher elevations of the Adirondacks and Green Mountains Saturday night as a closed upper low moves over the region which will provide dynamical cooling aloft with a change to snow over the higher elevations. Have leaned toward the warmer GFS MOS guidance for min temperatures Saturday night, as the NAM MOS guidance looks too cold. Also, combination of cloud cover and gusty west winds will help to keep air well mixed and will help to keep temperatures up. Thus, have lowered snowfall amounts a bit from the previous forecast given a slower changeover to snow in the higher elevations. Models showing precipitation winding down across the region Sunday morning, with most of the activity done by midday on Sunday. Models show the region will still be under cyclonic flow Sunday night from the departing surface low pressure area over Quebec Sunday night. Have kept in some slight chance pops for rain or snow showers Sunday night.
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As of 400 AM EDT Friday...The north country remains under cyclonic flow from the departing surface low pressure area over eastern Quebec Monday and Tuesday. Thus, have kept in slight or low chance pops for rain or snow showers for Monday and Tuesday. High pressure will build slowly east from the Great Lakes Tuesday night, with mainly fair and dry weather from Tuesday night through early Thursday. On Thursday, a warm front will approach the region from the Great lakes and the Ohio valley. Have put in a chance of rain showers into the forecast for mainly Thursday afternoon.
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&& .AVIATION /08Z Friday THROUGH Tuesday/... Through 06z Saturday...MVFR/IFR conditions persist throughout this long duration event, coming to an end Sunday night. Rain more persistent over Nrn NY this morning through early afternoon. Then increased moisture from subtropical system feeds into the NE low affecting our area Friday afternoon. This will allow resurgence in moisture and rain to spread east as the NE low swings from PA to the srn New England coast Friday night. Winds gusty where it isn`t raining and LLWS possible over SLK this morning. Low level jet weakens and exits east early Friday. Outlook 06z Saturday through Tuesday... 06z Saturday through 00z Monday: A prolonged period of unsettled conditions is expected with widespread MVFR/IFR in periods of rain. 00z Monday through 00z Wednesday: A mix of VFR/MVFR with upslope showers in NW flow. && .HYDROLOGY... As of 350 PM EDT Thursday...A widespread and long duration rainfall of 1 to 3 inches with amounts near 4 inches across the St Lawrence Valley from tonight through 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. The latest guidance from the NERFC brings Ausable River near minor flood stage by Saturday Afternoon. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...KGM/MV NEAR TERM...Evenson/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.