Area Forecast Discussion
Issued by NWS Burlington, VT
Issued by NWS Burlington, VT
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812 FXUS61 KBTV 231323 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 923 AM EDT Mon Sep 23 2024 .SYNOPSIS... Stationary high pressure across New England will remain in place through Tuesday. An approaching frontal system from the Great Lakes region will spread mid and upper level clouds across the North Country today, along with a chance for light rain showers across the St. Lawrence Valley. A stronger upper level low will finally bring a wetting rain to the region Wednesday into Thursday. Temperatures will slowly trend downward over the next several days, but generally remain above average for late September. && .NEAR TERM /THROUGH TUESDAY/... As of 913 AM EDT Monday...Despite light radar returns over northern NY, no measurable precipitation has been reported at the surface in our CWA. Further west however, observations show of a few hundredths of an inch just east of Lake Ontario, so still think we will squeak out some sprinkles into Saint Lawrence County this morning. The incoming rain continues to run up against ridging just to the east. Have made some updates to hourly temperatures this morning as strong temperatures gradient is observed over Vermont. Currently reporting temps in the upper 50s to around 60 in the CPV, and then in the low to mid 40s east of the Greens as relatively cooler onshore air wraps up and around the ridge axis. As the ridge gradually shifts east, temps over eastern Vermont will moderate a bit, and the temperature gradient will lessen as the day progresses. Previous discussion follows... Previous discussion...High pressure will continue to dominate across the region today while a weakening shortwave trough approaches from the Great Lakes. Fairly widespread shower activity associated with the trough can be seen marching eastward into eastern Ontario/western NY early this morning. The question remains how long this precipitation can hold together as it encounters the persistent ridge and drier airmass over our region. While hi-res guidance is somewhat mixed on how extensive shower coverage will be, expect at least a few showers will make it into the St Lawrence Valley a bit later this morning. Have increased PoPs just a bit through early afternoon across St Lawrence County with isolated to widely scattered activity seems most likely. Regardless, any showers will be light with just a few hundredths of rainfall expected. From the Adirondacks eastward, main impact from the trough will be ample cloud cover with perhaps just a few sprinkles west of the Champlain Valley. This increased cloud cover will serve to keep temperatures a bit cooler than previous days; highs will generally6 be in the mid 60s to around 70F. A tightening pressure gradient between the weakening trough and resident ridge will keep south to southeast winds a little on the breezy side, generally 5 to 10 mph with gusts around 15 mph. Any showers that do make it into the St Lawrence Valley will dissipate late this afternoon and evening, with dry weather expected through the remainder of the near term period thereafter. Clouds will lessen overnight, and anticipate partly to mostly clear skies by daybreak Tuesday. Clouds will begin to increase again late Tuesday ahead of our next system, especially across northern NY. After lows mid 40s to mid 50s tonight, the increased sunshine on Tuesday will allow temperatures to warm into the upper 60s to low 70s. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/... As of 310 AM EDT Monday...Tuesday night into Wednesday will start with a warm front trying its best to push against our persistent dry, high pressure. There will be a shortwave riding over an upper ridge axis along coastal England that will slowly give way. With a pocket of deep moisture associated with the shortwave, we will observe a surge of precipitation lift northwards and exit north along the international border midday. There should be a brief break in precipitation heading into Wednesday night. Breezy southeast to southerly flow is expected as well with gusts 15 to 25 mph. With rain showers and the developing warm front, it`ll be a fairly cool day. Some locations east of the Greens may struggle to climb above 60, while the rest of the region should at least lower to mid 60s. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... As of 310 AM EDT Monday...Models are in great agreement, despite a relatively complicated set up. An upper low across the Mississippi River Valley will fail to phase with the northern stream trough and rather begin to interact with a developing tropical cyclone. So a strong northern stream upper low will dive southeast across the North Country Wednesday night into Thursday bringing additional rounds of showers until the attendant surface low and potent cold front dive southeast Thursday night. Higher moisture fluxes will remain south as the future tropical systems gets entangled with the upper low across the lower Mississippi River Valley. In the wake of the cold front, strong mid- level ridging will build over the weekend and shunt any tropical moisture away from our region. Despite the strength of the cold front, the brunt of cold advection will be to our east, and so we will likely end warmer behind the system simply from the lack of cloud cover and increasing thicknesses with mid- level ridging. So the weekend is shaping up to be a gorgeous one across the region, with near to slightly above normal temperatures in the mid 60s to lower 70s during the day and 40s to lower 50s at night. && .AVIATION /13Z MONDAY THROUGH FRIDAY/... Through 12Z Tuesday...VFR conditions will prevail over the next 24 hours with a mix of BKN-OVC mid/high clouds expected through the daylight hours today. Clouds will start to scatter out after 00z Tuesday. A few showers will be possible in the St Lawrence Valley until about 18z, but no visibility restrictions expected at this time. South to southeast winds 4 to 8 kt, with some gusts to around 15 kt possible at KPBG/KBTV, trending back toward light and variable after 00z Tue. Outlook... Tuesday: VFR. NO SIG WX. Tuesday Night: VFR. Slight chance SHRA. Wednesday: Mainly MVFR, with areas VFR possible. Chance SHRA. Wednesday Night: Mainly MVFR, with local IFR possible. Likely SHRA. Thursday: Mainly MVFR, with local IFR possible. Chance SHRA. Thursday Night: Mainly VFR, with local MVFR possible. Slight chance SHRA. Friday: Mainly VFR, with local IFR possible. NO SIG WX. && .MARINE... As of 315 AM EDT Monday...A Lake Wind Advisory is in effect through this morning. South winds of 15 to 25 kt will persist through about mid morning, with the strongest winds occurring over the broad lake. Wave heights of 3 to 5 ft can be expected on the broad lake, with 1 to 3 ft elsewhere. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Hastings NEAR TERM...Duell/Hastings SHORT TERM...Haynes LONG TERM...Haynes AVIATION...Hastings MARINE...Hastings