382 FXUS61 KBTV 291928 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 328 PM EDT Mon Jun 29 2026 .WHAT HAS CHANGED... As of 325 PM EDT Monday... Excessive Heat Watch has been issued for the Champlain Valley and Eastern Windsor County in Vermont from 16Z Weds through 23Z Friday for daily heat index values near 105 degrees. && .KEY MESSAGES... As of 325 PM EDT Monday... 1. Major to localized extreme heat risk expected Wednesday thru Friday with heat index values near 105 degrees possible in the Champlain Valley/Eastern Windsor and 95 to 100 elsewhere. 2. Daily chances for showers and thunderstorms increase on Tuesday and continue through Thursday, some localized strong to severe storms possible. 3. Dangerously hot and humid conditions will linger into the holiday weekend along with daily chances of showers and thunderstorms. && .DISCUSSION... As of 325 PM EDT Monday... KEY MESSAGE 1: A long and dangerous heat wave is expected to impact the fa from Weds into the upcoming holiday weekend, as a strong mid/upper lvl heat ridge builds acrs the central Appalachian Mountains. Progged 925mb temps are expected to be in the 26-29C range for Weds and Thurs, which is 99th-100th percentile for our cwa, indicating the significance of this upcoming heat wave. In addition, 2m dwpts wl continue to climb Tues thru Thurs with many areas seeing values in the 68-75F range, during max heating. This wl create heat index values around 105F in the watch area and 95 to 100F outside the watch, where eventually heat advisories wl likely be needed. The warmest day continues to be Thursday acrs our cwa with high temps in the lower 90s mtns to upper 90s warmer valleys. A few record high temps are likely to be broken on during this heat wave. The boundary layer moisture wl result in very muggy conditions overnight with lows upper 60s to upper 70s most nights. KEY MESSAGE 2: Very challenging fcst with regards to thunderstorm potential and intensity on Tues and Weds, given large spread in potential solutions from CAMS. SPC has upgraded most of our cwa to slight risk (2 out of 5) for severe with 15% wind and 5% tornado prob. Mid/upper lvl ridge over the Ohio Valley/Great Lakes wl be expanding toward our cwa, while convectively induced vorts wl be ejecting from northern Rockies trof acrs southern Canada and diving southeast acrs the Mid Atlantic/NE CONUS Tues thru Thurs. On Tues the heat/humidity and associated instability wl be expanding northward toward our cwa, creating a potential boundary for convection to follow. The best instability looks to be located acrs our western and central cwa, with less over the NEK. HREF mean CAPE shows values near 300 J/kg over the NEK, 1000 J/kg CPV and 1500 J/kg over the SLV on Tues aftn with 0 to 6 km shear of 40 to 50 knots. Guidance spread is rather large on placement of convection on Tuesday with some CAMS having the convection over central NY, while others have it over central Maine. However, the gradient is progged to be acrs our cwa and that is typically a place where convection likes to travel. The HRRR/RRFS and RAP indicate a potential busy day for convection, while NAM3KM/ARW and WRF NSSL is much less robust with convection. An EML was evident in some guidance as warm dry air in the 700-500mb layer was progged to advect off the southern Rockies and move around the periphery of ridge and toward the northeast CONUS late Tues into Weds. If convection does occur, given available instability/shear and pw's surging above 1.50", gusty winds, hail and heavy down pours are possible. Have not placed enhanced wording in grids yet, given the uncertainty in timing/placement of convection for Tues. Similar type of scenario is expected on Weds and Thurs with daily potential for strong to locally severe thunderstorms. If you have outdoor plans, please keep an eye to the sky and be ready to seek shelter if threatening weather approaches your location this week. KEY MESSAGE 3: Friday is likely to be our third day in a row with at least heat advisory conditions in place as maximum temperatures reach the upper 80s to mid 90s. Have a chance of showers and thunderstorms mentioned on Friday as a weak cold front will drop into our area from Canada. This front will then remain draped somewhere across or very near to our forecast area through the weekend. This means there will be additional chances for showers and thunderstorms on both Saturday and Sunday, but it may not be as hot as previous days since clouds and precipitation can help damper the afternoon maximum temperatures. Each day should be a few degrees cooler than the previous day. Minimum temperatures remaining in the 70s in some locations will make it tough to cool off and accumulating warm days will take its toll. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... Through 18Z Tuesday...Through 18Z Tuesday...Very quiet aviation forecast period over the next 24 hours at all 7 terminals. Winds will be light and skies mostly clear with only FEW to SCT mid to high clouds at times. PBG has developed a light lake breeze this afternoon with winds out of the east off the lake which will become light to calm overnight. Do not believe we will reach crossover temperatures overnight, so left mention of fog out of the forecast at this time. Outlook... Tuesday Night: VFR. Chance SHRA, Chance TSRA. Wednesday: VFR. Chance SHRA, Chance TSRA. Wednesday Night: VFR. Chance TSRA, Slight chance SHRA. Thursday: VFR. Slight chance SHRA, Slight chance TSRA. Thursday Night: VFR. Chance SHRA, Chance TSRA. Friday: Mainly VFR, with local MVFR possible. Chance SHRA, Slight chance TSRA. Friday Night: VFR. Slight chance SHRA, Slight chance TSRA. Independence Day: Mainly VFR, with local MVFR possible. 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...Extreme Heat Watch from Wednesday afternoon through Friday evening for VTZ001-002-005-009-011-021. NY...Extreme Heat Watch from Wednesday afternoon through Friday evening for NYZ028-035. && $$ WHAT HAS CHANGED...Taber DISCUSSION...Taber/Neiles AVIATION...Neiles CLIMATE...NWS BTV