textproduct: Gray - Portland

WHAT HAS CHANGED

A coastal flood statement has been issued for the southern coasts for tonight's high tide.

KEY MESSAGES

1. Smoke from wildfires in Ontario shifts south of the area this evening before meandering back north Thursday into southern NH and SW Maine.

2. An isolated thunderstorm or two could bring gusty winds through this evening. Cold front brings scattered showers and thunderstorms Thursday afternoon. Storms Thursday afternoon could produce strong winds, mainly across the mountains towards the Maine coast.

3. High astronomical tides bring water levels to near flood stage again tonight.

4. Seasonable summertime conditions continue from the end of the week and into next week, with at least a couple chance for rain.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

A seasonably strong mid level gradient and upper jet continues to channel wild fire smoke from Ontario towards the Northeast this afternoon based on the latest satellite imagery. The centroid of the smoke plume has gradually shifted south through today and recent runs of the HRRR show this plume will continue to shift south through tonight. This will lead to cleaner looking skies across but far SW Maine with smoke still impacting portions of southern and western NH. Smoke should clear south of New Hampshire tonight. Recent runs of HRRR show that the smoke plume will shift back north Thursday morning into south-central NH and far SW Maine. A cold front will cross Thursday afternoon and evening that will shift the smoke south of the area by Thursday night.

KEY MESSAGE 2 DESCRIPTION...

Residual boundary layer moisture combined with filtered surface heating has allowed for 250 to 500 J/kg of MU CAPE to develop this afternoon. CAMs suggest an isolated thunderstorm or two could develop through early this evening. PoPs are limited to 15 to 25 percent across the mountains towards the Mid Coast and any sustain storm could produce some gusty winds.

A cold front approaches from the north Thursday and its passage will be well timed with peak heating. Boundary layer moisture will be limited, keeping CAPE less than 1000 J/kg. CAMs generally advertise a broken line of showers and storms moving south from the mountains towards the Maine coast Thursday afternoon and evening. Steep low level lapse rates and strong winds in the low levels may allow for storms to produce gusty winds approaching 50 mph. Storms will dissipate Thursday evening with the loss of heating.

KEY MESSAGE 3 DESCRIPTION...

High astronomical tides bring water levels to near flood stage again tonight. A coastal flood statement has been issued addressing this. With west-northwest winds through the overnight, residual surge should gradually decrease through high tide tonight, so water levels are expected to be slightly lower than last night's high tide.

KEY MESSAGE 4 DESCRIPTION...

A seasonable summertime pattern settles in by the end of the week, with temperatures in the 70s to low 80s across most of the area. A trough settles across northeastern Quebec and Labrador, keeping a west-northwesterly flow ongoing into the weekend. This keeps seasonable airmasses from interior Canada present into early next week, and also presents the chance for showers and storms this weekend as a low pressure system traverses the jet stream between the trough and a ridge to the southwest.

There's still some uncertainty on the rain timing for this weekend, but at this time it looks like rain chances increase by Saturday afternoon and into the overnight hours. Scattered showers would still be possible on Sunday, but Sunday looks like the drier day overall.

The pattern looks to remain pretty consistent for early to midweek next week with continued highs in the 70s and low 80s each day. The next chance for widespread showers would likely arrive around the Wednesday timeframe, with the chance for some tropical moisture to be drawn northward along the Eastern Seaboard and into New England.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

Through Thursday night...Mainly VFR. Gusty WNW winds subside this evening. WNW winds will increase Thursday morning gusting to 20 kts during the afternoon. Scattered TSRA will track from the mountains towards the Maine coast Thursday afternoon bringing potential for TEMPO restrictions at HIE, AUG, RKD, and PWM. Storm chances diminish Thursday evening with winds subsiding Thursday night.

Outlook...

Friday - Saturday Morning: VFR Prevails.

Saturday Afternoon - Sunday Morning: MVFR to IFR possible with widespread showers and storms likely.

Sunday Afternoon - Tuesday: VFR returns and prevails, with scattered afternoon showers possible across northern terminals. Nighttime valley fog will be possible.

MARINE

Winds and seas remain below SCA thresholds through Thursday night. Offshore winds turn SW Thursday ahead of a cold front. The front crosses Thursday evening shifting winds back offshore Friday.

Fair conditions prevail from Friday into Saturday. A cold front then crosses the waters late Saturday night and Sunday. SCA conditions in westerly flow are possible behind the front late Sunday and into Monday. Broad high pressure returns early next week with fair conditions.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...None.