Area Forecast Discussion

WHAT HAS CHANGED

As of 231 PM EDT Thursday...

Forecast is on track with building heat and thunderstorms possible this afternoon and tomorrow afternoon.

KEY MESSAGES

As of 231 PM EDT Thursday...

1. Building heat and humidity will impact the region with potentially dangerous conditions today in Windsor County and more widespread for Friday.

2. Isolated to scattered thunderstorms are expected today with a cold front potentially bringing stronger thunderstorms Friday afternoon.

3. More seasonable temperatures are expected for next week, with additional chances for showers.

DISCUSSION

As of 231 PM EDT Thursday...

KEY MESSAGE 1: Current temperatures as of 2 PM range from upper 70s in the Northeast Kingdom up to around 90 degrees in the southern Champlain valley and northern Connecticut river valley. Heat index values are pushing into the lower 90s in some spots. Some showers and a few thunderstorms may form this afternoon limiting max temperatures slightly. Tomorrow, temperatures will be even warmer as 925mb temps rise in the 23-27C range. Ridging will be sufficient to cap morning/early afternoon convection from the Champlain Valley eastward, so heat indices are expected to climb into the mid/upper 90s for the Champlain Valley and portions of the Connecticut River Valley. Heat advisory for parts of the region remains in place, see NPW for further info.

KEY MESSAGE 2: We continue to expect isolated to scattered thunderstorms this afternoon into the evening hours. Thus far, not much upstream to look at, though there are some signals of clouds bubbling up. With high temperatures and dewpoints this afternoon, shouldn't take too much to get some storms going. Not anticipating as much coverage as last night. A few of these storms could be heavy rainers with 1.5+inches of PWAT and expected slow movement.

Friday should be busier than today. Temperatures will be quite warm in the afternoon once again. CAPE will build beneath a capping inversion until a cold front sweeps through the region. Shear will increase to around 30kts supporting more favorable dynamics for organized convection. Shear coupled with 1500 to potentially 2500 J/kg CAPE will support at least isolated stronger variety thunderstorms. SPC also has most of the region under a Slight risk of severe thunderstorms given heat, moisture, and a good triggering mechanism. While storms are expected to be moving, some locations that have received heavy rainfall may be susceptible to flooding. This will be especially true for areas where roads have washed out.

KEY MESSAGE 3: As we head into the beginning of next week, temperatures look to trend back towards seasonable normals after a stretch of hot and humid weather as a weak upper level trough shunts the warmer air to the south. High temperatures for next week look to generally be in the 70s to lower 80s across the region, with dewpoints generally in the 40s and 50s making it feel much more comfortable than the current weather. A few chances of diurnally driven showers and possibly a thunderstorm will be possible afternoon with the upper level trough and cooler air aloft, but exact timing and location will be difficult to pinpoint, although no day looks to be a complete washout at this point.

AVIATION /00Z FRIDAY THROUGH TUESDAY/

Through 00Z Saturday...VFR conditions currently prevail across all terminals this evening. There have been a few pop-up showers but not near terminal sites and activity should diminish. Humid airmass, calm windsand plentiful rainfall yesterday indicated stratus and fog possible for our typical KSLK, KMPV sites with potential IFR/LIFR in the 07-11z timeframe. Elsewhere some cloud cover but should still be VFR/MVFR.

VFR conditions aft 12z Friday with light winds (5-6kts)with showers and possible TSRA developing in northern NY in the 18-21z timeframe and in VT from 20-23z. Right now it looks scattered so not all locations will witness a TSRA.

Outlook...

Friday Night: VFR. Chance SHRA. Saturday: VFR. NO SIG WX. Saturday Night: VFR. NO SIG WX. Sunday: VFR. Chance SHRA, Slight chance TSRA. Sunday Night: Mainly VFR, with local MVFR possible. Definite SHRA, Chance TSRA. Monday: Mainly VFR, with local MVFR possible. Slight chance SHRA. Monday Night: VFR. NO SIG WX. Tuesday: VFR. Slight chance SHRA.

CLIMATE

Record High Temperatures:

June 11: KMPV: 88/2017

June 12: KBTV: 94/2017 KMPV: 88/2017 KPBG: 94/2017 KMSS: 89/2005 KSLK: 90/1933

Record High Minimum Temperatures:

June 11: KBTV: 71/2017 KPBG: 70/1976 KSLK: 66/1984

June 12: KBTV: 71/2017 KPBG: 67/2017 KSLK: 62/1996

BTV WATCHES / WARNINGS / ADVISORIES

VT...Heat Advisory from noon to 8 PM EDT Friday for VTZ001-002-005- 009-011-021. Heat Advisory until 8 PM EDT this evening for VTZ021. NY...Heat Advisory from noon to 8 PM EDT Friday for NYZ028-035.