textproduct: Gray - Portland

WHAT HAS CHANGED

No significant changes were made to the previous forecast.

KEY MESSAGES

1. High pressure brings mostly dry weather and seasonable temperatures through the weekend.

2. A ridge gives way to a troughing pattern by late this weekend and into next week, with generally seasonable days and a couple chances for rain.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

Northwesterly winds will ease early this evening with mainly clear skies expected tonight. These clear skies and light winds will allow for strong radiational cooling. Forecast lows range from the lower 40s across the northern valleys with upper 40s to lower 50s in most other locations. Valley fog is possible towards dawn, which may result in some localized visibility restrictions.

Surface high pressure will remain centered over New England on Friday into Friday night. This will result in mainly sunny skies and near average high temperatures into the lower 80s in most locations south of the mountains. Radiational cooling is likely once again Friday night with low temperatures falling into the 40s and 50s, coolest in valley locations.

Pleasant conditions are then expected this weekend with continued low humidity and comfortable high temperatures into the lower 80s and low temperatures mainly into the 50s.

KEY MESSAGE 2 DESCRIPTION...

An upper level low becomes stationary and deepens across Hudson Bay by this weekend. A ridge passes through New England early this weekend, and then as the upper level low strengthens, troughing becomes more favored into the Northeast by early next week.

With high pressure at the surface, a mainly sunny day with highs in the upper 70s to mid 80s is expected for Saturday. The high slides offshore during the day, bringing in a steady southeasterly flow along the coast that knocks temps back by the afternoon hours.

Sunday sees a few more clouds and is likely cooler by a few degrees in easterly flow as a plume of moisture mostly passes offshore. There is still a small chance that this could trend a little closer and bring a chance for showers on the coast on Sunday, but at this point the forecast looks mainly dry.

By Monday and Tuesday, a slow moving system approaches from the west. This brings an increasing chance for showers into western New Hampshire on Monday, and then showers and storms are likely across most of the area by Tuesday. Temperatures still look to warm into the upper 70s to mid 80s each day, with any showers and storms primarily in the afternoon hours. The front associated with the system likely takes until Wednesday to clear through New England, so a chance for showers and storms continues into Wednesday as well.

By late in the week, ridging likely begins to build back in as the trough weakens, favoring a return to drier and slightly warming conditions.

AVIATION /18Z THURSDAY THROUGH TUESDAY/

Through 18Z Friday: VFR conditions expected. The exception is at KLEB and KHIE where some valley FG is possible, especially between 09Z-13Z Friday. NW winds will become light and variable this evening and remain light on Friday. An afternoon sea breeze is possible across coastal TAF sites on Friday. No LLWS is anticipated through the period.

Outlook...

Saturday - Monday: VFR prevails.

Monday Night - Wednesday: Showers and storms likely bring brief periods of MVFR to IFR conditions. But outside of any rain, mainly MVFR to VFR ceilings are expected.

Wednesday Night - Thursday: Mainly VFR likely.

MARINE

Seas outside of the bays and east of Portland will remain at 3-6 ft through late this evening. Otherwise, winds and seas will remain below SCA criteria through Friday night. Mainly fair conditions are expected this weekend through Monday as high pressure slides east of the Gulf of Maine. A cold front then slowly approaches from the west, with SCA conditions in southerly flow possible by Tuesday, and continuing into Wednesday. High pressure then returns by late week.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...Small Craft Advisory until 2 AM EDT Friday for ANZ150-152.