184 FXUS61 KBTV 282313 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 713 PM EDT Sun Jun 28 2026 .WHAT HAS CHANGED... As of 312 PM EDT Sunday... Temperatures for Tuesday and Wednesday have been reduced slightly to account for increased cloud cover and precipitation chances. Dangerous heat still looks on track Wednesday through the holiday weekend. The threat for severe weather has increased for Wednesday. && .KEY MESSAGES... As of 312 PM EDT Sunday... 1. Dangerous heat expected on Wednesday. Heat headlines will likely be needed in the coming days. 2. Strong to severe thunderstorms possible Tuesday and Wednesday. 3. Dangerously hot and humid conditions prevail into next weekend with daily chances of scattered showers and thunderstorms expected. && .DISCUSSION... As of 312 PM EDT Sunday... KEY MESSAGE 1: We will see a gradual warming trend over the next several days with temperature slowly approaching 90 degrees by Tuesday afternoon across southern Vermont. The latest deterministic and ensemble guidance has dropped temperature a few degrees Tuesday afternoon as increased cloud cover and rain chances from a shortwave trough moving overhead will coincide with peak heating. Nevertheless, temperatures in the mid to upper 80s with dewpoints climbing into the mid 60s can be expected. The jury is still out on how warm Wednesday will be as cloud cover is expected to persist across the region in the wake of widespread showers and thunderstorms that will be exiting the region Wednesday morning. This will initially stunt our diurnal heating which may limit our ability to warm into the mid 90s. Another fly in the ointment will be scattered to numerous showers and thunderstorms Wednesday afternoon may also inhibit heating. The NBM thinks we could warm all the way up to 97 degrees in the wider valleys on Wednesday but the latest thinking is that we will likely be more in the 90-94 range with the possibility of not even breaking 90 degrees in some areas. Still, with dewpoints surging into the lower 70s Wednesday afternoon, heat indices will climb between 95 and 103 for most, if not all, locations. This would warrant the issuance of a heat advisory if trends continue to show these heat indices and confidence increases. KEY MESSAGE 2: Surface high pressure will shift off to the east Tuesday morning while we remain under the northern periphery of an impressive 500 mb high pressure system. Models continue to keep the center of the upper level high well to our south which will leave us with northwesterly flow aloft. Several shortwave disturbances are expected to move through the region on Tuesday and Wednesday with scattered to numerous showers and thunderstorms. Tuesday will be the tricky day as the shortwave timing will likely be during the evening and overnight hours, thus limiting surface instability. The NAM and GFS both show elevated thunderstorms capable of small hail and very heavy rain but without these storms being rooted in the boundary layer, it's very likely we see any strong to severe wind gusts. Nevertheless, it's impressive to see what the models are showing overnight as it's not a typical set-up for some stronger thunderstorms. Wednesday looks significantly more likely that we could see severe weather across the Northeast. Temperatures at or above 90 degrees, dewpoints near or above 70 degrees, and a strong shortwave should all come together to produce a robust round of thunderstorms during the afternoon hours. Models are showing CAPE values between 1500 and 2000 J/kg and 0-6 km shear of 40-45 knots. This is plenty for some supercells to develop so it'll be worth watching closely as Wednesday approaches. KEY MESSAGE 3: Large scale synoptic pattern shows mid/upper lvl ridge anchored over the central Appalachian Mtns thru most of the upcoming week, while the westerly flow aloft with embedded s/w's are progged to be near the International Border. This expanding heat ridge wl produce dangerously hot and humid conditions for Thurs and Friday, with the peak of the conditions expected on Thurs. The latest heat risk analysis shows widespread moderate to major impacts with localized extreme values possible in the Champlain Valley on Thurs and Friday, with slight improvement by Saturday. Current forecast by WPC shows highs on Thurs upper 80s to mid 90s, with some localized upper 90s expected near VSF, while dwpts are in the 60s, supporting heat index values btwn 95 and 100 degrees. Similar type conditions are forecasted by WPC for Friday, before cooler and slightly drier air develops by next Saturday. The chances for thunderstorms wl be closely associated with timing of s/w energy in the westerly flow aloft for Thurs thru next weekend. The expanding ridge axis on Thurs may push the strongest dynamics along and north of the International Border, while mid lvl cap is possible acrs most of our cwa. As better dynamics and moisture arrive late Thurs into next weekend, the idea of aftn/evening showers and storms looks reasonable. Given the progged sfc based CAPE values in the 1500-2500 J/kg and 0-6km deep layer shear of 30 to 40 knots, the potential for strong to severe storms wl need to be watched. Also, the nw to se orientation of multiple rounds of daily convection with favorable pw's and high precip efficiency (high precip rates), given the tall convective structure, localized heavy rainfall and flash flooding will be possible too. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... Through 00Z Tuesday...High pressure with light winds and mainly clear skies/VFR expected overnight. Just an outside chance of some brief, patchy IFR in fog/mist at KSLK/KMPV in the 09-11Z time frame. Confidence of this occurring is modest at best, however, as we've had another 24 hours to dry out the surface/top soil layers. After 12Z Monday, VFR continues under light northerly flow less than 10 knots as high pressure remains atop the region. Outlook... Monday Night: VFR. NO SIG WX. Tuesday: VFR. Chance SHRA, Slight chance TSRA. Tuesday Night: Mainly VFR, with areas MVFR possible. Chance SHRA, Chance TSRA. Wednesday: Mainly VFR, with local MVFR possible. Chance SHRA, Chance TSRA. Wednesday Night: VFR. Chance SHRA, Chance TSRA. Thursday: Mainly VFR, with local MVFR possible. Chance SHRA, Chance TSRA. Thursday Night: VFR. Chance SHRA, Slight chance TSRA. Friday: VFR. Chance SHRA, Chance TSRA. && .CLIMATE... Extreme heat and humidity is possible later this week, especially on Wednesday and Thursday, which could lead to some daily records. Below are the current daily high and low temperature records in jeopardy at our area climate sites. Record High Temperatures: June 30: KBTV: 93/2018 July 1: KBTV: 96/2018 KMPV: 92/2018 KPBG: 94/1968 KMSS: 94/2018 July 2: KBTV: 97/2018 KMPV: 90/2018 KMSS: 94/2018 July 3: KMPV: 91/2002 Record High Minimum Temperatures: July 1: KBTV: 76/2018 KPBG: 73/1971 KSLK: 69/2018 July 2: KPBG: 77/2002 KSLK: 68/2002 July 3: KBTV: 76/1911 KPBG: 73/2002 July 4: KPBG: 71/1973 KSLK: 67/1952 && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ WHAT HAS CHANGED...Clay DISCUSSION...Taber/Clay AVIATION...JMG CLIMATE...NWS BTV