textproduct: Gray - Portland

WHAT HAS CHANGED

Only minor adjustments needed to the going forecast at this time.

KEY MESSAGES

1. High pressure slides offshore tonight, then low pressure brings the chance for severe storms and rain on Saturday.

2. Seasonable summertime conditions expected into next week, with another chance for widespread showers and storms Tuesday and Wednesday.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

High pressure slides offshore during the overnight hours tonight. Another seasonably cool night is expected, with lows dipping into the upper 40s to mid 50s across most of the area. Clouds begin to increase from the west during the overnight hours.

Low pressure tracks through the Saint Lawrence Valley during the daytime tomorrow. Temperatures have a brief window to warm up before increased cloud cover and showers arrive, with New Hampshire and western Maine holding the best chance to warm into the 80s. Additionally, smoke is also expected to make a return during the daytime tomorrow on southwesterly flow. This will keep temps from reaching their full potential, and is also likely to bring some reduced air quality.

Showers and storms arrive from the west during the afternoon hours. There remains a marginal risk for severe storms across most of New Hampshire to the Maine border. Wind gusts look to be the main concern with these storms. The storms then push through during the late afternoon and evening hours, moving offshore by midnight.

The cold front likely takes until near daybreak on Sunday to fully clear the area. This keeps overnight lows on the milder side, with lows generally ranging from the mid 50s across the north, to mid 60s along the coast.

KEY MESSAGE 2 DESCRIPTION...

We dry out on Sunday in the wake of a cold front on gusty NW winds up to G30 MPH. Low humidity values will be present with highs around 70 in the mountains and around 80 on the coastal plain and across southern NH.

Dry weather continues with SFC high pressure moving well to our southeast. As such, this will set up a southerly return flow regime with warmer temperatures and slightly more humidity.

A fairly deep short wave trough will approach Tuesday and Wednesday. This will bring increasing chances for widespread showers and perhaps a few thunderstorms Tuesday through Wednesday evening due to the slow-moving nature of the trough. Heavy downpours will be possible as PWATs rise to above 1.5 inches. A few strong to severe thunderstorms as well depending on the positioning of a warm front and any potential sunny breaks.

Finally, still monitoring how much wildfire smoke will affect the region into next week, as those Canadian wildfires are expected to continue burning for the foreseeable future. It seems plausible a stronger burst of northwest flow on Sunday will push the smoke plume south of New England, but there is a potential it could return north/overhead sometime next week with periods of decreased air quality.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/

Through Saturday night...VFR prevails into Saturday morning, and then restrictions are possible at all terminals during the afternoon and evening hours in showers and thunderstorms. Some valley fog is possible tomorrow night, but otherwise VFR returns once the showers and storms move offshore around midnight.

Outlook...

Sunday: Conditions expected to return to VFR in the morning, except lingering MVFR ceilings and SHRA possible at HIE.

Monday: VFR expected.

Tuesday-Wednesday: MVFR to IFR possible with increasing chances for SHRA and a few TSRA.

MARINE

Southerly winds freshen on Saturday ahead of an approaching cold front. Gale force gusts are likely further offshore, with high end SCA conditions likely across the coastal waters and bays Saturday afternoon into the nighttime. A few gusts to 35kt are possible. Seas then take until at least Sunday morning to lower below 5ft.

Sunday-Thursday... The front crosses early Sunday morning, shifting winds to W and NW. Seas could stay above 5 ft much of the day Sunday. High pressure builds in for Monday, keeping conditions under SCA levels, and then the next front brings another chance at SCA conditions toward the middle of next week (be Tues-Weds or Weds- Thurs).

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...Small Craft Advisory from 2 PM Saturday to 8 AM EDT Sunday for ANZ150-152-154. Small Craft Advisory from 2 PM Saturday to 2 AM EDT Sunday for ANZ151-153. Gale Warning from 4 PM Saturday to 2 AM EDT Sunday for ANZ180- 182.