Area Forecast Discussion
Issued by NWS Burlington, VT
Issued by NWS Burlington, VT
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334 FXUS61 KBTV 070047 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 847 PM EDT Thu Jun 6 2024 .SYNOPSIS... Moderate to locally heavy rain showers are expected this evening as a front moves through. The rest of the week into early next week will feature cool temperatures and shower chances most days as an upper-level low stalls overhead. && .NEAR TERM /THROUGH SATURDAY/... As of 736 PM EDT Thursday...Forecast is largely on track. A line of showers with embedded downpours and isolated thunder associated with the occluded front is approaching the Champlain Valley. Isolated gusts of up to 40 mph are possible. Forecast remains largely on track. When thunder roars, go indoors. PREVIOUS DISCUSSION...A cold front will sweep through from west to east this evening, with the frontal passage marked by a line of moderate to locally heavy rain showers with some embedded thunderstorms. Expect the heavy showers to move through northern NY between 3 PM and 7 PM, moving into the Champlain Valley between 6 PM and 10 PM. During the evening hours, the rain showers will become lighter as the line moves into eastern Vermont. The main hazard this evening associated with the showers/storms will just be locally heavy rainfall, with precipitable water values analyzed between 1.5 and 1.8 inches in northern NY and relatively deep warm cloud depths. Rainfall amounts upstream have locally exceed 1.3 inches in places, but most areas have picked up between a quarter and three quarters of an inch. Storm total precipitation amounts for our forecast area this evening range from 0.75 to 1.1 inch over northern NY and into northwestern VT, then generally around a half inch for eastern VT. We should be able to handle these amounts without any real issues, although we could see some ponding of water in poor drainage areas. Will be watching hydro closely through the evening. Overnight tonight, showers will weaken and diminish in coverage. We will see some patchy fog/mist form, especially over valleys in eastern Vermont. Overnight lows will be in the low to upper 50s. The core of a deep upper-level low will shift into southeastern Ontario Friday. As the low approaches our forecast area, mid-level height falls, steepening lapse rates, and multiple shortwaves rotating around the upper low will promote showery conditions. Expect coverage and intensities of showers to increase through the day along with increasing diurnal instability. 700 to 850 mb lapse rates will peak around 7.5 to 8.5 deg C/km Friday midday/afternoon, coincident with blossoming coverage of showers. Between 100 and 500 J/kg SBCAPE will develop during the afternoon, highest over northern and western counties (closest to the core of the low), thus expect some isolated embedded thunderstorms within the showers. Potential for developing instability and thunderstorms will remain dependent on any clearing in the clouds. Even if we do see thunderstorms, severe weather isn`t expected as the better shear will remain displaced to the east of the best instability. High temperatures for Friday will be in the low to mid 70s for much of the area, locally in the upper 70s to 80 in the Champlain and Connecticut River Valleys. Showers will diminish in coverage Friday night with the loss of diurnal instability. Overnight lows will be in the 50s for most areas, locally in the upper 40s in the Adirondacks. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... As of 316 PM EDT Thursday...Overall, the weekend will be showery as an upper level low will be in place to the north of the region. However, the showers will be on and off so it will not be raining the entire time, especially in the broad valleys. Diurnal heating and cold temperatures aloft will cause scattered to numerous showers to develop in the afternoons. Two shortwaves pivoting around this low will pass through, one around Saturday morning and one late in the day on Sunday into Sunday night. Very weak ridging will build in Saturday night. Because of the cold air aloft, there will still be daytime showers when the ridging is in place but they should be less numerous than in the shortwaves. The shortwave Sunday night should be able to keep some showers over the area at night, even without the diurnal heating. There is the chance for an isolated thunderstorm on Saturday or Sunday afternoon, but they would be non- severe and a vast majority of the convective showers will contain no thunder. Temperatures during this period will be slightly under normal to around normal. Highs will be between 65-75 and lows will be in the 50s and upper 40s. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... As of 316 PM EDT Thursday...One final shortwave pivots through on Monday and it will help increase the showers again during the day. These showers look to be lighter and less widespread than over the weekend and the chance of thunder looks lower as well. The upper level low should mostly move out of the region Monday night and ridging will begin to build in. A lingering shower is possible on Tuesday but it looks like it should be mostly dry. A weak storm system will move through the region later in the week but right now it looks like it will relatively unimpactful. Temperatures should trend above average by mid to late week but any significant heat looks unlikely. && .AVIATION /01Z FRIDAY THROUGH TUESDAY/... Through 00Z Friday...Cold front continues to track east. The tropical airmass is causing rain in a narrow band to produce 3/4SM to 2SM visibility and quick accumulations. Periodically, there have been embedded gusts within the line, but the winds are expected to weaken heading east. After 04z, shower activity will shift east. Some LLWS is possible at KEFK and KMPV through about 05z along the frontal axis with south winds around 35 knots at 2000 ft agl. As skies clear tonight and with recent rain and very humid conditions, fog will be possible, but not guaranteed due to 15 knot winds just off the surface. Beyond 10z or 11z fog should dissipate, with mainly south to southwest winds across the region at 5 to 10 knots. Pop up showers and a few storms will develop beyond 15z Friday. Outlook... Friday Night: Mainly VFR, with local MVFR possible. Chance SHRA. Saturday: Mainly VFR, with areas MVFR possible. Chance SHRA. Saturday Night: Mainly VFR, with local MVFR possible. Chance SHRA. Sunday: Mainly VFR, with local MVFR possible. Likely SHRA, Slight chance TSRA. Sunday Night: Mainly VFR, with local MVFR possible. Chance SHRA. Monday: Mainly MVFR, with local IFR possible. Chance SHRA. Monday Night: Mainly VFR, with areas MVFR possible. Slight chance SHRA. Tuesday: VFR. Slight chance SHRA. && .CLIMATE... Based on the current forecast, daily records are possible at some climate sites. Record daily precipitation is possible at Massena and Plattsburgh today. Record Precipitation: June 6: KPBG: 1.05/2008 KMSS: 1.09/1953 && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Duell NEAR TERM...Chai/Duell SHORT TERM...Myskowski LONG TERM...Myskowski AVIATION...Haynes CLIMATE...Kutikoff/Kremer