Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 250804 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 404 AM EDT Thu May 25 2017 .SYNOPSIS... Gusty downslope winds are expected today, especially across the southern and central western slopes of the Green Mountains with isolated power outages possible. A band of light rain will lift from south to north across the North Country today...with rainfall amounts generally less than a quarter of an inch. Steadier rain will redevelop tonight and continue into Friday. The upcoming weekend with feature a dry Saturday with some scattered showers possible late Sunday into Monday. && .NEAR TERM /THROUGH TONIGHT/... As of 402 AM EDT Thursday...Wind advisory in effect from 11 AM Thursday to Midnight for localized gusts to 50 mph along the central and southern western slopes of the Green Mountains. Forecast concerns today are winds...followed by timing of light rain showers. Water vapor shows deep closed full latitude mid/upper level trof across the Ohio Valley with strong feed of deep layer moisture over the eastern conus. Surface analysis places 994mb low pres over central Ohio this morning...with developing gradient associated with departing 1015mb high pres and increasing 925mb to 850mb wind profiles. Winds are tricky local btv 2 and 4km...along with the latest 3km NAM show some uncertainty in magnitude and areal coverage of strongest wind fields. Unlike the wind event on May 5th, the 925mb to 850mb winds are 10 to 15 knots weaker on all solutions...along with weaker low pres and departing high pres. BTV 2km and Nam 3km continue to show strongest core of 925mb winds of 45 to 55 knots across central/southern Greens between 18z-00z today. Investigating sounding data closely shows bottom of the mix layer around 40 to 42 knots at Rutland...but thinking with some downslope warming and better mixing...some slightly stronger gusts are possible. This thinking also matches the surface gust potential off the NAM 3km...which shows values between 40 and 45 knots across the central/southern western slopes of the Green Mountains...but values quickly taper off over the northern core of strongest 925mb winds weakens. Thinking gusts between 45 and 50 mph looks good from just east of Danby to Wallingford to just east of Rutland to East Middlebury with 35 to 45 mph for Nashville/Underhill areas. Some isolated power outages possible...along with some downed small trees and limbs...but less impact than the May 5th event. Models in good agreement with band of warm air advection rain showers lifting from south to north across our cwa between 15z and 20z today. Expecting a 2 to 4 hour window of mainly light rain showers...which will be highly terrain driven in terms of qpf placement...given the low level wind fields. Qpf will range from <0.10 along the downsloping regions of the western slopes/eastern CPV/NEK and western dacks...with a 0.25 or so on the southeast upslope areas of the eastern dacks/southeast greens. The initial surge of favorable lift/upper level divergence will be north of our cwa by 20z today...resulting in much less areal coverage of precip and mainly over the se upslope regions. Meanwhile...water vapor shows potent 5h vort in the flow aloft over central NC...will help to enhance shower/storms across the mid Atlantic States this aftn. This deeper moisture and stronger lift will help to redevelop another round of rain showers aft 06z tonight. Expecting heavier qpf values with amounts between 0.25 and 0.50...mainly CPV and points east. Temps mainly upper 50s to upper 60s today and holding in the 50s overnight with clouds/precip. && .SHORT TERM /FRIDAY/... As of 445 PM EDT Wednesday...During the day Thursday, vertically stacked low pressure system will slowly track from the Ohio river valley Northeastward towards our CWA. Light rain will spread southwest to northeast across our forecast area, especially after 15z. Low pressure system then tracks off the coast of New England overnight and into the Gulf of Maine on Friday. Two areas of deeper low level moisture will miss us, one to our Northwest and one to our Southeast. Have lowered rainfall totals a bit, mainly a third of an inch to an inch of rain is expected. GFS is showing an evident dry slot moving across our area from 18z through about 03-06z. During this time will see some winds mix down to the surface on strong low level east/southeast jet, strong Easterly flow will cause downsloping in Rutland County as well as Eastern Addison and Eastern Chittenden counties. Have issued a wind advisory, please see NPW. As low pushes east off the New England coast Friday best forcing goes with it and precipitation will become more showery. Temperatures will remain mild through the period, generally 50s at night and 60s during the day. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... As of 340 PM EDT Wednesday...The synoptic pattern will be shifting towards a more pleasant weekend as vertically stacked low pressure system will be pulling off the New England coastline. This leaves a few scattered showers over the eastern portion of Vermont as the moisture will be decreasing through the evening hours. The more welcomed portion of the forecast will be the high pressure that builds in for Memorial Day weekend. As ridging occurs at the surface there may be a stray shower or two but otherwise we can expect highs in the upper 60s to lower 70s with partly cloudy skies with a few breaks in the that areal coverage. The latest trends in the guidance has been to slow down how quickly the next system is to move into the region. In the broad sense, an upper level low pressure system will track west of the Great Lakes and lift a warm front through the North Country and then later on will swing a cold front through. The timing on this has been even further delayed such that we may get through much of Sunday with quiet weather and nice conditions to be outdoors or perhaps going for a run. Towards Sunday evening and into Monday morning, expect that warm front to lift north and bring a chance for scattered showers into Monday. By Monday mid-morning early afternoon a pre- frontal trough will swing through with shortwave energy aloft and bring showers with perhaps some embedded thunderstorms. The GFS depicts decent instability with marginal elevated instability along with decent 0-6km shear and moderate lapse rates. So the idea of some showers with embedded thunderstorms looks good based on the 12z guidance timing. Heading into the rest of the mid week we should see a break on Tuesday before the actual front swings through on Wednesday renewing our chances for showers. Temps through the period will be depend on the timing of the fronts but the general idea is upper 60s to lower 70s for high and lows starting off in the upper 40s over the weekend and gradually warming to the low to mid 50s by mid week. && .AVIATION /08Z THURSDAY THROUGH MONDAY/... Through 06Z Friday...Aviation concerns will be gusty southeast winds at Rutland today...followed by lowering cigs with some mvfr conditions expected by this evening. As low pres approaches...gusty southeast winds will develop with localized gusts to 40 knots possible at Rut between 17z-01z today. Expect areas of moderate to severe turbulence...especially near the terrain. Meanwhile...a ribbon of rain will move from south to north across our taf sites btwn 15-21z with mainly vfr conditions...trending toward mvfr cigs at mpv/mss/pbg by 00z this evening. As winds shift to the north...expect lowering cigs at btv/rut by 06z Friday. Downslope southeast flow will keep vfr conditions at rut/btv through today. Additional showers are expected to redevelop aft 04z tonight and continue into Friday. Outlook... Friday: VFR/MVFR. Likely SHRA...RA. Friday Night: VFR. Slight Chance SHRA. Saturday: VFR. Slight Chance SHRA. Saturday Night: VFR. NO SIG WX. Sunday: VFR. Chance SHRA. Sunday Night: VFR. Chance SHRA...TSRA. Memorial Day: VFR/MVFR. Chance SHRA...TSRA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...Wind Advisory from 11 AM this morning to midnight EDT tonight for VTZ011-017>019. NY...None. && $$ SYNOPSIS...Taber NEAR TERM...Taber SHORT TERM...Neiles LONG TERM...Deal AVIATION...Taber is the U.S. government's official web portal to all federal, state and local government web resources and services.