Area Forecast Discussion
Issued by NWS Burlington, VT

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279 FXUS61 KBTV 231735 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 135 PM EDT Thu Mar 23 2017 .SYNOPSIS... A strong area of high pressure will crest over the North Country this afternoon bringing mostly sunny conditions and light winds. Temperatures will moderate a bit, with daytime highs mainly in the upper 20s to lower 30s. A warm front will approach from the southwest on Friday, with overcast skies and a developing wintry mix across the North Country. Some light accumulations of snow and sleet are expected Friday morning before transitioning to mostly rain later in the day. The frontal zone will become quasi-stationary near or just south of our region over the weekend, with the potential for additional mixed wintry precipitation later in the weekend. && .NEAR TERM /UNTIL 8 PM THIS EVENING/... As of 713 AM EDT Thursday...Strong sfc anticyclone (1036mb) centered over wrn NY at 11z/Thu will be our controlling wx feature today as it translates ewd across the nern CONUS. A chilly start at sunrise with -18F at KSLK and +3F at KBTV (within 2 deg of a record low at BTV). Air mass will undergo some moderation today, aided by sunny skies and a relatively high late March sun angle. Looking for afternoon highs 27-32F, warmest in the Champlain/St. Lawrence/CT river valleys. Once nocturnal inversions mix out, will see NW winds generally 5-10 mph thru mid aftn, then becoming light and variable toward this evening. PoPs NIL, but will see some increasing cirrus clouds from the west late this afternoon into this evening. && .SHORT TERM /8 PM THIS EVENING THROUGH FRIDAY NIGHT/... As of 200 AM EDT Thursday....High pressure shifts east of our longitude overnight and into the Gulf of Maine by 09-12z Friday. This will allow for a light S-SW return flow to develop. Aloft, will see a warm front approaching from wrn NY and sern Ontario, and increasing 850-700mb WAA will result in thickening mid-level overcast. These factors will keep overnight temperatures generally in the mid teens to lower 20s, with a tendency for a slow rise in temps toward daybreak Friday, especially west of the Green Mtns. Moderately strong 850-700mb WAA with approaching warm front brings developing stratiform precipitation beginning during Friday morning from SW-NE. It appears thermal profiles will initially support snow, with a transition to sleet/rain as the day progresses. Subfreezing thermal profiles will persist longest across central/ern VT and in the nrn Adirondacks, where 1-3" of wet snow/sleet are forecast. Should see generally 1" or less wet snow in the Champlain Valley as PBL temperatures warm more quickly thru the 30s. Could see some minor impacts to travel especially around the time of onset of the mixed wintry precipitation (and especially away from the Champlain Valley), and will continue to highlight in the Hazardous Weather Outlook. Afternoon highs on Friday generally 36-39F, except 33-34F across portions of ern/nern VT. First wave of low-level WAA passes to our east Friday evening/night, but E-W oriented low-level frontal zone will become quasi-stationary across nrn NY/nrn VT. May be a tendency for a shallow nly wind shift after midnight with strong high pressure building into wrn Quebec, so we`ll need to monitor trends with the frontal position overnight with possible shallow CAA near the intl border. Anticipate continued overcast skies, but with just very light rain/drizzle or isolated pockets of snow/sleet/freezing drizzle across far nrn areas. Temperatures will generally hold in the low-mid 30s. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 309 AM EDT Thursday...Interesting forecast with rather active period expected and above normal chances for mixed precipitation. Large high builds down from Canada on Saturday and pushes surface boundary southward out of the area...which will help bring precipitation to an end during the morning hours. Highs will range from the mid 30s along the Canadian border to the upper 30s and mid 40s elsewhere. Northwest flow aloft Saturday night continue to bring colder and drier air into the region. An upper trough will move east from the Ohio Valley and this will allow the boundary that moved out of our area on Saturday to return northward into our region and enhance the potential for precipitation...especially Sunday afternoon and night. Thermal profile suggests mixed precipitation with surface cold air holding in the longest across eastern Vermont Sunday night into Monday. Precipitation should become rather widespread Sunday night into the first part of Monday as the trough moves across the area. Will have to monitor this situation closely in case there will be a need for a winter weather advisory. There will be a brief respite in precipitation Monday night into the first part of Tuesday...but another trough of low pressure will move toward the region later Tuesday into Wednesday and bring more precipitation to the area. Still cannot rule out some mixed precipitation...but at this time looking at either rain or snow with this system. The precipitation should be fairly widespread as well given the strength of the upper trough moving into the region. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/...
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Through 18Z Friday...VFR through 12Z as high pressure gives way to approaching warm front and associated pcpn. SKC expected through 00Z, then slowly thickening/lowering VFR OVC in the 00Z to 12Z time frame. Winds light/modest northwesterly through 00Z, trending light overnight. After 12Z Friday widespread snow overspreads all terminals, likely transitioning to a snow/sleet/rain mix from Champlain Valley terminals west toward the end of this forecast cycle. Winds trending southerly 5 to 15 knots, most pronounced at KBTV/KPBG where valley channeling effects may push gusts near 25 kts. Outlook 18Z Friday through Tuesday... 18Z Friday through 18Z Saturday...widespread light mixed pcpn likely, slowly settling southward and lessening in coverage by Saturday afternoon affecting mainly southern terminals at that point. Highest threat of mix to occur at northern terminals. 18Z Saturday through 12Z Sunday...trending mainly VFR/pcpn-free as Canadian high pressure noses briefly southward into the area. 12Z Sunday through 12Z Tuesday...widespread mixed pcpn and/or rain return to the region. 12Z Tuesday onward...light and spotty mixed pcpn transitions toward a period of steadier rains by Wednesday.
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&& .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Banacos NEAR TERM...Banacos SHORT TERM...Banacos LONG TERM...Evenson AVIATION...JMG

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