Area Forecast Discussion
Issued by NWS Burlington, VT
Issued by NWS Burlington, VT
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899 FXUS61 KBTV 061128 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 728 AM EDT Sat Jul 6 2024 .SYNOPSIS... Numerous showers and thunderstorms will roll through the forecast area this morning, with more hit or miss activity this afternoon before dissipating after sunset. Drier days are forecast for Sunday and Monday although remaining humid at the ground and warm. Another round of showers and thunderstorms likely late Tuesday into Wednesday along a cold front passage. Slightly cooler and less humid air returns midweek. && .NEAR TERM /THROUGH SUNDAY/... As of 728 AM EDT Saturday...Overnight convection is coming to an end across northern New York and northern Vermont as it shifts east of the CT River Valley within the next hour. An abundance of lightning and heavy rain was observed with several locations reporting 1-1.5" of rain in a short period of time. As this activity winds down, remnant showers and isolated thunder from an MCS that developed across eastern PA will shift through southern Vermont through mid-morning with additional light to moderate rain there. After all the morning convection passes after the noon hour, we should see breaks of sunshine develop and with surface dewpoints still well into the upper 60s to lower 70s instability will grow with progged SBCAPE`s in the 1000-1500 J/kg range. A weak cold front to our west and some embedded shortwave energy riding northeastward ahead of the parent upper trough over the Great Lakes should provide the necessary lift to spark some additional showers and thunderstorms in the afternoon, but should be fairly widely scattered. Some storms could become strong, though as the previous forecaster mentioned, the presence of some mid- level dry air and 50-60kts of 0-6km shear may hamper updraft development. Certainly areas to watch for isolated flash flooding will be where the greatest rainfall footprints are from the morning convection, which will likely be across Rutland, Windsor, and Orange counties. Convection generally dissipates after sunset but with the frontal passage not expected until after midnight, the warm and humid airmass will likely support some isolated showers and perhaps some embedded thunder through the first half of the overnight. Drier conditions generally follow for Sunday though a weak boundary north of the border may help to spark some isolated showers across border towns. Not enough to cancel any outdoor plans for sure, but temps will once again be rising into the mid/upper 80s and dewpoints remain in the 60s producing a moderate heat risk for some VT locales. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... As of 351 AM EDT Saturday...Sunday night should be cooler than of late, with mostly clear skies and light winds promoting good radiational cooling. Some of the colder hollows could see lows in the lower 50s with upper 50s to low 60s for many locations. Warmest spots would once again be across the urban centers of the Champlain valley with lows in the mid 60s. Surface high pressure moves overhead on Monday, which should prove to be a decent day for outdoor activities with comfortable humidity. Temperatures will once again peak in the mid 80s to near 90, but with mixing up to 850-800mb, lower dew points should be mixed down to the surface so expect plentiful sunshine with breezy southwest winds helping to make being outdoors rather pleasant for the North Country in mid July. By Monday night, winds will shift to the south as an upper level disturbance approaches from the Great Lake with overnight lows generally in the 60s. && .LONG TERM /TUESDAY THROUGH FRIDAY/... As of 351 AM EDT Saturday...Upper ridging starts to break down on Tuesday as a positively tilted upper level trough approaches from the Great Lakes. As such, shower and thunderstorm chances do return on Tuesday. NAEFS ensemble situational awareness table shows PWATs and IVT rising to over 90th percentile for our region later Tuesday into Wednesday, so multiple rounds of heavy rainfall is certainly possible with a slow-moving cold front nearby providing the focus for scattered to numerous thunderstorms. Looking upstream, the anomalous PWAT plume appears to have its origins in the Gulf of Mexico. The orientation of the approaching upper trough does allow for the possibility of TC Beryl- related moisture to stream towards the Northeast. PWATs rise to around 2 inches on Tuesday with some deterministic guidance even showing upwards of 2.3 to 2.5 inches. For reference, the daily max of climatology for Albany, NY upper air site around mid July is around 2.1 inches. Fortunately for our area, the consensus of guidance shunts the plume of richest PWATs south of our area later Tuesday into early Wednesday. There are indications that the unusually moist air mass could coincide with the better dynamics for stronger storms that would further enhance the rainfall, but mid- range guidance still unsurprisingly differ on the timing of the surface cold front. Right now, WPC has continued to highlight a marginal risk for excessive rainfall for Day 4 (Tuesday into Tuesday night) across the entire CWA but not Day 5 (Wednesday into Wednesday night). Those with outdoor plans middle of next week are advised to stay up to date with the latest forecast. Additionally, if drier weather were to prevail, parts of the Champlain valley and Connecticut valley could see heat index values rise into the lower and mid 90s. WPC heat risk does highlight potential for widespread moderate heat-related impacts for Tuesday so the temperature trends are worth monitoring as well in addition to heavy rainfall and thunderstorms. Cold front should finally clear the region later Wednesday into Thursday, leading to at least a couple of days with more seasonable temperatures (upper 70s to mid 80s) and comfortable humidity (dew points in the 50s) for mid July standards. Having said that, the aforementioned plume of tropical enhanced moisture continues to linger across the Mid Atlantic states into Southern New England. By Friday, a warm front may be lifting northwards again and we might once again get into the more humid if not oppressive air mass. Stay tuned. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... Through 12Z Sunday...Lingering low clouds from overnight convection across central/northern areas will be lifting to VFR within the next couple of hours, with a brief period of MVFR/IFR likely at KRUT as remnants of another convective complex shifts through. After 15Z, isolated showers and thunderstorms are possible through the afternoon, but confidence on hitting a terminal is low so have only included VCSH. After 00Z, convective wanes and skies should trend clearer, but this opens the door for IFR fog to develop. Best chance of occurrence is at KSLK, KMPV, and KEFK. Outlook... Sunday: VFR. Slight chance SHRA, Slight chance TSRA. Sunday Night: VFR. Patchy BR. Monday: VFR. NO SIG WX. Monday Night: VFR. NO SIG WX. Tuesday: VFR. Chance SHRA, Slight chance TSRA. Tuesday Night: MVFR/IFR conditions possible. Likely SHRA, Slight chance TSRA. Wednesday: Mainly MVFR, with local IFR possible. Chance SHRA, Slight chance TSRA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Lahiff NEAR TERM...Lahiff SHORT TERM...Chai LONG TERM...Chai AVIATION...Lahiff