Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 211747 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 147 PM EDT Fri Oct 21 2016 .SYNOPSIS... Rain event persists over the North Country as a mid-level longwave trough continues to dig south and east from Canada. This trough will become negatively tilted late Friday into early Saturday, keeping frontal boundary, associated surface low pressure system and rain over the region through Saturday night/early Sunday. Colder air will filter in behind this system along with northwest flow producing upslope rain and snow showers Sunday through Tuesday. Another surface low pressure system looks to affect the Northeast Thursday. && .NEAR TERM /THROUGH SATURDAY/...
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As of 133 PM EDT Friday...Precip across the Adirondacks and St Lawrence Valley has shifted west for now and has led to a short break until and additional moisture from the south moves in later this afternoon. The first sign of tropical moisture is moving from the south as well up the NY/MA boarder and into Southern VT. This will lead to enhanced activity for the next few hours over Central and then Northern VT over the next few hours. Wit the positioning of surface low pressure, winds directions are markedly sharp the region with northern winds West of the northern half Champlain Valley and areas east of the Greens and south of the of Rutland still southerly and gusty. This has led to a wide temperature scale with 40`s and 50`s in the northern flow areas and 60`s to 70`s in the southern influenced areas. As the Low progresses the northerly flow and lower temps should move across all of Vt by evening. Models continue to indicate more moisture from coastal system will continue to feed into the NE low pressure system latter this evening . This combined with diffluent mid-level flow will result in possible periods of moderate rain over VT, mainly during the overnight hours. Saturday morning, models find more consensus on surface low positioning along the southern New England coast, traversing northward during the day. This means deep NW flow over the North Country will bring in colder air and terrain enhanced rain showers.
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&& .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... 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. && .LONG TERM /MONDAY THROUGH THURSDAY/... 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. && .AVIATION /18Z Friday THROUGH Wednesday/... Through 12z Saturday...Varying flight conditions across the North Country. Mostly 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. While Champlain Valley sites will see periods of VFR with downsloping winds aiding in low level drying. Increased moisture from subtropical system feeds into the NE low affecting our area Friday afternoon. This will result in widespread MVFR conditions returning to the Champlain Valley around 20Z. KMSS/KMPV/KSLK...persistent IFR/LIFR conditions expected for the next 24 hrs. KPBG/KBTV/KRUT...MVFR with breaks of VFR early today, deteriorating to MVFR in mid-afternoon through tonight. Low level wind shear this morning before winds mix down this morning. Then winds shift out of the north this afternoon. KMSS/KSLK already experiencing north winds continue til tonight. Outlook 12z Saturday through Tuesday... 12z 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 425 AM EDT Friday...Rainfall amounts ranging from 1-1.5 inches have already fallen across the St Lawrence Valley, northeastward across the northern Champlain Valley this morning. Rain will continue today through Sunday, being most persistent over the St Lawrence Valley and Adirondacks. An additional 1 to 3 inches is expected. 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...KGM/MV NEAR TERM...KGM SHORT TERM...WGH LONG TERM...WGH AVIATION...KGM HYDROLOGY...KGM is the U.S. government's official web portal to all federal, state and local government web resources and services.