textproduct: Burlington

WHAT HAS CHANGED

As of 225 AM EDT Wednesday...

No significant changes were made with this forecast package. Dangerous heat will continue through much of the second half of the week, and Excessive Heat Warnings and Heat Advisories remain in place through Friday. While showers and thunderstorms are still possible each afternoon, strength and areal coverage is still very uncertain.

KEY MESSAGES

As of 225 AM EDT Wednesday...

1. Major to localized extreme heat risk is expected through Friday with widespread heat index values of 95F to 105F. Some locations could exceed 105F heat index due to very warm air temperatures and dewpoints rising into the 70s.

2. Daily chances for showers and thunderstorms will continue through Friday. Some of these could be strong to severe, but there remains considerable uncertainty in areal coverage and timing.

3. Dangerously hot and humid conditions will linger into the holiday weekend along with daily chances of showers and thunderstorms.

DISCUSSION

As of 225 AM EDT Wednesday...

KEY MESSAGE 1: A prolonged and dangerous heat wave will impact Vermont and northern New York through the latter half of the week as a strong heat ridge builds into the central Appalachians. Widespread temperatures in the upper 80s to mid 90s start today and will persist through at least Friday. Thursday will be the warmest day with just about everyone hitting 90F, and some locations could approach 100F. Unfortunately, humidity will also be on the increase; dewpoints will be in the upper 60s to mid 70s. This will not only make for dangerous heat index values exceeding 100F in places, it will keep the overnights very warm and muggy, limiting any relief from the hot and humid daytime hours. We'll see a bit of a respite from the humidity Friday and Saturday, but it will still be very warm and muggy.

Heat related impacts will increase through the week due to the cumulative effects from the prolonged heat wave. Please make sure to take proper heat safety precautions, including limiting your time outdoors and seeking indoor shelter with air conditioning. Check on your relatives and neighbors, especially if they are elderly. And don't forget about your pets; bring them indoors or provide them with ample shade and fresh cool water.

KEY MESSAGE 2: A swath of light to moderate rain with embedded rumbles of thunder continues to push south-southeastward across the region early this morning. This should gradually weaken and remain elevated through daybreak. Thereafter, there remains considerable uncertainty on convective potential over the next few days. Heat and humidity will combine to create impressive SB CAPE values of 2000-3000 J/kg today and 1000-2000 J/kg on Thursday, with some indications of values exceeding 3000 J/kg at times. Shear will be less impressive, generally 25-35 kt depending on the model and day, perhaps increasing to 40+ kt Thursday afternoon. With no strong forcing mechanism other than the abundant instability, expect mainly terrain- induced convection today, generally remaining isolated to perhaps scattered in coverage. Strong to severe thunderstorms can't be ruled out given the large CAPE values; SPC continues to encompass our entire forecast area in a Slight Risk (level 2 out of 5) in their latest Day 1 severe outlook. And as one would expect with the amount of humidity, we're also in WPC's Marginal Risk (level 1 out of 4) for excessive rainfall. Any storms that pop up today would at the least produce heavy rainfall, though widespread flooding is not anticipated.

Additional thunderstorms are possible Thursday and Friday, though marginal mid-level lapse rates due to loss of the EML will limit instability and likely areal coverage/intensity for any convection on Friday. We are included in a Marginal Risk (level 1 out of 5) in SPC's Day 2 severe outlook. Friday is more uncertain, both in areal coverage and potential storm severity. Still, given the upcoming holiday festivities, we urge everyone to stay tuned to later forecast updates as strong/severe thunderstorms can't be totally ruled out any one day.

KEY MESSAGE 3: Heading through the weekend into next week, warm weather looks to linger, although temperatures and heat indices will not be as warm as the week above. Current forecast shows temperatures generally in the 80s areawide, with temperatures gradually trending cooler heading into the start of next 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. There looks to be chances for showers and thunderstorms throughout the weekend with the proximity of the frontal boundary moving through the area, which may also help keep temperatures cooler. There continues to be a lot of uncertainty in this time range in regards to precipitation chances heading into next week, with a wide range of model solutions.

AVIATION /06Z WEDNESDAY THROUGH SUNDAY/

Through 06Z Thursday...Primarily VFR conditions across terminals as showers and thunderstorms continue to move through the region overnight. Shower activity is expected to persist for the next few hours, before tapering off towards 09Z. Some more widespread MVFR ceilings are possible through the early morning, generally between 09Z and 15Z, with all terminals expected to improve back towards VFR. Some additional shower/thunderstorms will be possible tomorrow afternoon, but there continues to be low confidence in any timing or impacts. Southerly winds will generally be less than 10 knots throughout the forecast period, with some channeled southwesterly winds at KMSS tomorrow afternoon making it a little breezier.

Outlook...

Thursday: VFR. Chance SHRA, Chance TSRA. Thursday Night: VFR. Chance SHRA, Chance TSRA. Friday: VFR. Slight 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. Saturday Night: Mainly VFR, with local MVFR possible. Slight chance SHRA. Sunday: VFR. Slight chance SHRA, Slight chance TSRA.

CLIMATE

Extreme heat and humidity will affect the region for the latter half of the week, 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:

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...Heat Advisory from noon today to 7 PM EDT Friday for VTZ003- 004-006>008-010-016>020. Extreme Heat Warning from noon today to 7 PM EDT Friday for VTZ001-002-005-009-011-021. NY...Heat Advisory from noon today to 7 PM EDT Friday for NYZ026- 027-029>031-034-087. Extreme Heat Warning from noon today to 7 PM EDT Friday for NYZ028-035.