textproduct: Burlington

WHAT HAS CHANGED

As of 232 AM EDT Friday...

No significant changes were made to the previous forecast as unusual heat continues for one more day.

KEY MESSAGES

As of 232 AM 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 232 AM EDT Friday...

KEY MESSAGE 1: Today will mark our third consecutive day with widespread heat index values in excess of 90. The Champlain Valley remains and hottest locale with high temperatures in the mid 90s support heat index values to around 100. While today's conditions will be slightly less oppressive than recent, heat impacts tend to be cumulative. Therefore, have opted to keep the Extreme Heat Warning in effect in the Champlain Valley and portions of the Connecticut River Valley rather than downgrading to an advisory. Fortunately, conditions trend drier Saturday as a relative cold front drops out of Canada. Winds will not be overly strong, but there is a decent dew point gradient and cool air advection that will support highs in the 80s Saturday and Sunday with dew points decreasing into the 60s and 50s respectively. Sunday will feel much more refreshing even with temperatures running a couple degrees warmer than average in the low/mid 80s.

KEY MESSAGE 2: The axis of highest instability for this afternoon will be tilting to a southwest/northeast orientation leaving much of Vermont in a general thunderstorm area while portions of southern Vermont and northern New York remain in an area with a marginal threat of a stronger variety thunderstorm. One significant change is from recent conditions will be the decrease in strength of the CAPE gradient in the vicinity of Ottawa. Still, PWATs remain elevated, so it's feasible that heat/instability will be enough to fire convection along the CAPE gradient and push a few storms through portions of northern New York in more of a northwest to southeast direction. For northern Vermont, the threat for thunderstorms will be more conditional on whether convection can get going over terrain with outflows driving surface convergence resulting in more isolated coverage of showers and thunderstorms; best chances remain over terrain.

An approaching boundary will keep some shower chances ongoing overnight and support very isolated thunderstorms overnight into Saturday. Can't rule out thunderstorms through the morning to around noon Saturday for northern Vermont. The front drops south through the day shunting convection chances southward as well. Winds will not be overly strong 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. 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.

KEY MESSAGE 3: Heading into next week, warm weather looks to linger, although temperatures and heat indices will not be as warm as the week above. At this time, high temperatures are most likely to range in the 80s and lower 90s with chances for showers and thunderstorms throughout the week. Overnight lows look to remain on the warmer side, generally in the 60s, which may lead to accumulating heat impacts. Although it looks like it won't be quite as hot as earlier in the week, it is important to remember to drink water and take frequent breaks if working outside, especially with such an extended period of warmer weather. While there will likely be several chances for afternoon shower and thunderstorm chances, there is still a lot of uncertainty at this point.

AVIATION /12Z FRIDAY THROUGH TUESDAY/

Through 12Z Saturday...VFR conditions currently prevail across all terminals, and are expected to persist through most of the forecast period. Winds will trend light and variable overnight, before increasing out of west/northwest towards the afternoon, with gusts between 15 ans 25 knots will be possible. Additional shower and thunderstorm chances will be possible throughout the forecast period, but there is low confidence in areal coverage and extent of any possible showers, so have left mention of them out of the forecast at this time. Potential for MVFR CIGs return overnight as a few showers remain possible for EFK/MPV/SLK. Should showers be persistent on these terminals, then a period of IFR cannot be ruled completely out either.

Outlook...

Independence Day: VFR. Chance SHRA, Slight chance TSRA. 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. 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...Heat Advisory until 7 PM EDT this evening for VTZ003-004- 006>008-010-016>020. Extreme Heat Warning until 7 PM EDT this evening for VTZ001- 002-005-009-011-021. NY...Heat Advisory until 7 PM EDT this evening for NYZ026-027- 029>031-034-087. Extreme Heat Warning until 7 PM EDT this evening for NYZ028- 035.