Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 261115 AFDBTV AREA FORECAST DISCUSSION National Weather Service Burlington VT 715 AM EDT Fri Apr 26 2019 .SYNOPSIS... A warm front associated with a developing storm system over the Ohio Valley will produce occasional showers today. As surface low pressure deepens, gusty southeast winds will develop along the Western Slopes this afternoon with the threat for scattered showers. Additional showers will develop along a cold front this evening with cool and unsettled weather anticipated for Saturday. Highs will range from the mid 40s eastern Vermont to upper 50s parts of the Champlain and Saint Lawrence Valleys, but cool back into the 30s and 40s on Saturday with some snow showers possible in the mountains. && .NEAR TERM /THROUGH SATURDAY/... As of 709 AM EDT Friday...Updated to expand 100% further north based on radar and observations. Also, cut temps by several degrees east of the Green Mountains where current readings are in the mid 30s to lower 40s. Several bands of rain will move across the cwa this morning, but still anticipating a decrease in areal coverage of precip this aftn as gusty southeast downslope winds develop. Precip will become more trrn focused on the southeast upslope side of the eastern dacks and portions of the southern/central Greens. Additional bands of occasional showers will become more widespread again this evening ahead of boundary. Water vapor shows maturing cyclone over the Ohio Valley with development of full latitude trof across the eastern Conus. Good moisture advection and associated lift associated with 925mb to 700mb waa will produce a 2 to 4 hour window of rain showers this morning across our cwa. After initial band of precip exits our northern cwa by 17z, expect more scattered trrn focused precip to develop as southeast 925mb to 850mb wind fields increase btwn 45 to 60 knots. Latest 00z guidance show deepening low pres over the Eastern Great lakes will track ne with a tightening sfc gradient anticipated as it encounters sfc high pres over northern Maine. This will produce gusty southeast downslope winds of 20 to 30 mph with localized gusts up to 50 mph along the western slopes. Thinking strongest winds with best mixing will occur btwn 2 PM and 8 PM this evening. Also, expect a secondary area of gusty winds across the northern slopes of the dacks near Malone with isolated gusts btwn 40 and 45 mph, just short of advisory criteria. The cool east/southeast flow will help advect modified Atlantic air mass into eastern/central VT, with temps mainly in the m/u 40s, while downslope sections of the CPV/western dacks warm into the mid/upper 50s to near 60f. Tonight, expect showers to redevelop along a sfc cold front/occlusion as 985mb low pres lifts into southern Canada. Latest RAP and HRRR show weak/narrow axis of some instability with CAPE values of 100 to 300 j/kg, especially across the southern SLV and western dacks, so would not be surprised of a rumble or two of thunder. The combination of strong 5h energy associated with developing negatively tilted mid/upper level trof along with advection of pw values near 1.0, support the idea of cat pops again overnight. Moderate to strong 925mb to 850mb caa develops on brisk westerly winds by 12z Saturday. Expect lingering rain showers to switch to some snow showers across the dacks, as 925mb to 850mb temps drop below 0c by 15z. Some minor accumulation is possible above 1500 feet on Saturday morning. Otherwise, expect a cold, cloudy, and raw Saturday with rain and mountain snow showers likely thru most of the morning hours. Some drier air develops late in the after with precip become more trrn focused btwn 18z-21z. Highs range from near freezing dack summits to mid/upper 30s greens to lower 40s slv to mid/upper 40s cpv and lower ct river valley. Event total qpf will range btwn 0.50 to 1.0 over the next 24 to 30 hours, which will produce some sharp in bank rises on local streams and rivers. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY/... As of 321 AM EDT Friday...Wrap around mountain showers will gradually wind down Saturday night as the upper low and best moisture push east of the area. Temperatures will drop into the lower to mid 30s, with upper 20s possible in the Adirondacks and Northeast Kingdom. Hence anticipate lingering rain showers could mix with/change to snow late, mainly over higher elevations. Snow accumulations, if any, would be minimal. Ridging and drier conditions briefly move in early Sunday morning, but this will be short lived as yet another shortwave brings showery conditions by afternoon. The bulk of the precip will be across central and southern portions of our forecast area, and given the system`s quick movement, don`t anticipate more than a tenth of an inch of rainfall across much of the region. Thickening cloud cover and cold air advection setting up in the afternoon will keep temperatures down in the 40s, with a few spots possibly peaking up above 50. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... As of 321 AM EDT Friday...Lots of uncertainty through much of next week, particularly from Tuesday onward. High pressure builds across the area on Sunday night, cresting overhead Monday morning. It`s a pretty cold airmass settling in, with 925mb temps progged to be -4C to -8C by 12z Monday. Question is how much radiational cooling we can get; clouds will decrease late Sunday night/early Monday, but we`ll still be under a bit of a pressure gradient, especially in eastern VT. Note that the MEX MOS continues to go quite cold, especially in NY; 26/00z guidance says a low of 15 Monday morning at KSLK. This is likely overdone, so have stayed close to the warmer Euro MOS for temps. This gives Sunday night lows in the mid 20s to lower 30s across the North Country. Monday will be dry with the high slowly crossing the area. Uncertainty grows thereafter with the longer- range guidance continuing to have any real model-to-model or run-to- run consistency. Anticipate rounds of showers as a series of shortwaves slide through the zonal flow aloft, but exactly where, when, and how intense this precipitation will be is very much still up in the air. Regardless, the cool and showery pattern looks to persist through much of next week. Stayed close to a model blend for Tue-Thu timeframe due to the uncertainty. && .AVIATION /11Z FRIDAY THROUGH TUESDAY/... Through 12Z Saturday...Aviation forecast will be challenging over the next 12 to 24 hours. All taf sites start out at vfr conditions this morning, but based on upstream obs expect some mvfr cigs/vis in the heavier showers between 12z-16z. Conditions will improve to vfr again, especially rut/btv and slk with downslope winds. However, more precip redevelops this evening with cigs trending toward mvfr. Breezy to gusty southeast winds will develop at 15 to 30 knots with localized higher gusts possible near Rutland this aftn. These winds associated with a strong low level jet of 45 to 55 knots will create areas of turbulence and wind shear, especially near complex terrain. Winds threat diminishes overnight, as cigs lower to mvfr with potential ifr cigs at mpv/mss and slk, as winds shift to the southwest. Some rain/snow showers with vis around 2sm likely at slk toward 12z Saturday. Outlook... Saturday: Mainly VFR, with areas MVFR possible. Chance SHRA. Saturday Night: Mainly VFR, with local MVFR possible. Chance SHRA, Slight chance SHSN. Sunday: VFR. Slight chance SHRA. Sunday Night: VFR. NO SIG WX. Monday: VFR. NO SIG WX. Monday Night: VFR. Chance SHRA, Chance SHSN. Tuesday: Mainly MVFR, with areas VFR possible. Chance SHRA. && .HYDROLOGY... As of 400 AM EDT Friday...Our latest forecast maintains continuity suggesting widespread light to moderate rainfall will affect the region on today into Saturday. Storm total rainfall ending at 18Z Saturday should range from 0.50 to 1.0 inch. With limited additional runoff input from snowmelt and the fact that vegetative green-up will begin to absorb some of the rainfall the threat of widespread stream/river flooding is not expected at this time. Lake Champlain remains in minor flood stage with levels generally ranging from 100.6 to 100.7 feet as of 400 AM Friday. With gusty south to southeasterly winds forecast on the lake today, enhanced wave action and seiche effects will likely push levels near or slightly above 101.0 feet (moderate flood level) across northern lake waters for a period of time. As such, those with interests in these areas should monitor the latest forecasts and take appropriate action as necessary to protect property. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...Wind Advisory from 1 PM this afternoon to 11 PM EDT this evening for VTZ016>019. NY...None. && $$ SYNOPSIS...Taber NEAR TERM...Taber SHORT TERM...Hastings LONG TERM...Hastings AVIATION...Taber HYDROLOGY...JMG

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