textproduct: Burlington

WHAT HAS CHANGED

As of 404 PM EDT Friday...

An Air Quality Alert has been issued for central and northern Vermont from 7 AM tomorrow morning to Midnight Saturday night due to Canadian wildfire smoke

KEY MESSAGES

As of 247 PM EDT Friday...

1. Today will be the last day of this heat wave with dangerous conditions continuing through the afternoon into the evening.

2. More thunderstorms are expected today and tomorrow with a few stronger storms possible again this afternoon.

3. Warm weather will linger into next week, along with daily chances of showers and thunderstorms.

DISCUSSION

As of 247 PM EDT Friday...

KEY MESSAGE 1: Today will mark our third consecutive and final day of our heat wave with widespread heat index values in excess of 90, with near 100F in the Champlain Valley and eastern Windsor County in Vermont. While temperatures today will be a degree or two lower than yesterday, in addition to lower dewpoints into the 60s, today's heat conditions will still be oppressive as heat impacts tend to be cumulative. With past overnight lows remaining warm, heat stress compounds on itself over days of prolonged heat. As such, we have continued the Extreme Heat Warning and Heat Advisories until 7 PM tonight. By this evening a cold front will track south from Canada leading to a relative reprieve from the heat into Independence Day. Highs will lower into the low to mid 80s, with increasingly dry air filtering in as well. Dewpoints throughout the day tomorrow will decrease behind the front falling into the low to mid 50s by tomorrow evening. Winds with the passage of the front will not be overly strong with only a light breeze overnight. Sunday will feel much more refreshing even with temperatures running a couple degrees warmer than average in the low/mid 80s.

In addition to falling temperatures and dewpoints, the passage of the cold front will bring some smoke south from Canada due to wildfires in both the Intermountain West and western Quebec. Reduced air quality is expected tomorrow for most of Vermont, beginning in the morning across northern Vermont, and by the early afternoon in southern Vermont.

KEY MESSAGE 2: Continued chances for showers and thunderstorms will exist this afternoon, though coverage and intensity will be less than previous days. SPC mesoanalysis denotes the axis of greatest instability is shifted to our southwest along the Lake Ontario lake breeze and southwest towards Rutland and Windham Counties in Vermont. Current GOES-19 satellite denotes an area of mid to upper clouds traversing the Ontario Peninsula in addition to bubbling cumulus towers along the western and northern Lake Ontario lake breeze. CAMs denote this activity associated with a weak shortwave drifting in the St. Lawrence Valley and tracking to the southeast before weakening over the Adirondacks. The timing of these showers and embedded thunderstorms will be between 5-9 PM. Given CAPE gradient is nudged south of our areas, the environment today does not look quite as favorable for severe activity. Most thunderstorms today will be more garden variety with some frequent lightning. Though a stronger thunderstorm with localized gusty winds may be possible. SPC continues to show a Marginal Risk (level 1 of 5) for stronger storms southwest of a line from Ogdensburg, NY to Rutland, VT. A few terrain driven showers and an isolated rumble of thunder is also possible across northern and central Vermont generally between 6-9 PM, though shower chances drop off quickly after 9 PM, as these showers will be tied to daytime heating.

Overnight tonight, a cold front will pass from north to south with a chance for showers and a morning rumble of thunder, primarily south of I-89, as it interacts with better CAPE profiles in southern Vermont. Showers will be isolated to scattered, and chances for severe weather are low to nil. The front will slow as it approaches southern Vermont with showers potentially lingering towards the late morning which may impact morning outdoor activities associated with Independence Day. Winds will not be overly strong with the front given the weaker thermal/pressure gradients, but some gusts to 20 mph will be possible along Lake Champlain and up to 30 mph for ridges. Drier air will advect southward with cooling temperatures aloft tomorrow afternoon. Models denote a few weak shortwaves behind the front tomorrow afternoon which could lead to an isolated shower areawide, though better chances will be located over the higher terrain. Any shower activity should taper off by mid to late tomorrow afternoon, just in time for dry and more comfortable conditions for afternoon and evening outdoor activities. Sunday will remain dry behind the front with transient high pressure overhead. By Monday, southwest flow is favored to return while diffluence increases aloft. A few showers and thunderstorms will be possible as instability increases from southwest to northeast through the day. so

KEY MESSAGE 3: Heading into next week, warm weather will linger, although temperatures and heat indices will not be as warm as currently. At this time, high temperatures are most likely to range in the 80s and lower 90s with chances for showers and thunderstorms each afternoon through midweek. Overnight lows remain on the warmer side, generally in the 60s, which may lead to accumulating heat impacts. The first part of the week won't be too hot though.

AVIATION /00Z SATURDAY THROUGH WEDNESDAY/

Through 00Z Sunday...VFR conditions currently prevail across all terminals, and are expected to persist through most of the forecast period. Potential for MVFR CIGs return overnight for EFK/MPV/SLK. Aft 12z...VFR with isold-sct -SHRA KRUT aft 16z. Winds will mainly be WNW at 5-10 kts.

Outlook...

Saturday Night: VFR. NO SIG WX. Sunday: VFR. NO SIG WX. Sunday Night: VFR. NO SIG WX. Monday: VFR. Chance SHRA. Monday Night: VFR. Chance SHRA. Tuesday: VFR. Chance SHRA. Tuesday Night: VFR. Slight chance SHRA. Wednesday: VFR. Slight chance SHRA.

CLIMATE

Extreme heat and humidity will continue today, which could lead to some daily records being tied or eclipsed. Below are the current daily high and low temperature records in jeopardy at our area climate sites.

Record High Temperatures:

July 3: KMPV: 91/2002

Record High Minimum Temperatures:

July 4: KPBG: 71/1973 KSLK: 67/1952

BTV WATCHES/WARNINGS/ADVISORIES

VT...Air Quality Alert from 7 AM Saturday to midnight EDT Saturday night for VTZ001>010-016>018. NY...None.