textproduct: Gray - Portland

WHAT HAS CHANGED

Updated the aviation section for the 12Z TAF package.

KEY MESSAGES

1. Expect fair weather with a significant warmup today and Thursday.

2. Very warm and mostly dry conditions continue on Friday before a cold front brings increasing chances for showers and scattered thunderstorms over the weekend.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

As an upper low continues to move well out to sea, the pressure gradient and winds will continue to relax this morning. Fog will once again be possible over the Connecticut River Valley but shouldn't last much longer than 12z or so.

High pressure settles in for today and Thursday with an upper level ridge axis approaching. This pattern will promote a significant warmup with dry and fair conditions. Highs today will mainly range from the lower 70s north to the lower 80s south. Most will then see highs in the lower to upper 80s on Thursday. Lows will be mild for this time of year tonight and Thursday night, mainly in the 50s with some 40s in the mountains.

KEY MESSAGE 2 DESCRIPTION...

Friday will again be very warm with temperatures well into the 80s across the region, possibly even 90 degrees in parts of southern NH. A cold front enters the picture later in the day from the north, which may bring a a couple of isolated showers or storms across far northern areas, but most will remain dry.

The front sags southward Friday night and over the weekend with increasing chances for showers and storms. Highest chances will be across the northern areas into the first part of Saturday, so those south of the mountains could see another warm day before more clouds fill in and showers/storms increase in coverage.

Showers remain likely Saturday night into Sunday (and a few storms possible) with cooler temperatures on Sunday thanks to the clouds and precip. Although there are still some timing differences, there's a strengthening signal in the ensembles for a north to south drying trend later Sunday or Sunday night as the front pushes farther south and high pressure starts to build in.

Southern areas may hold onto a few showers on Monday, but there's more support for upper ridging to build toward the Northeast to bring mostly dry conditions with a warming trend toward the middle of next week. That said, if the center of the upper high remains more toward the Great Lakes, can't rule out a couple of disturbances riding on top of the ridge into New England.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

Through 12Z Thu...VFR conditions will generally prevail with an afternoon seabreeze possible both today and Thu. Light and variable winds during the morning will become S-SE in the afternoon across coastal/southern TAF sites behind the sea breeze. Light winds will return at night.

Outlook:

Thursday night: VFR expected.

Friday: VFR expected. Can't rule out a shower or storm near HIE, but for now it looks like most precip will remain to the north.

Friday night-Saturday night: A cold front brings increasing chances for showers and storms and MVFR to IFR restrictions across the region, mainly for northern TAF sites Friday night and then generally areawide Saturday into Saturday night.

Sunday: Continued chances for showers/storms and IFR restrictions, especially the first half of the day on Sunday. Improvement from north to south is possible late in the day into Sunday, but this depends on how quickly the front pushes south.

Monday: Mostly VFR, but can't rule out a few lingering showers across southern NH.

MARINE

Conditions will remain below SCA levels through Thursday with warming temperatures as high pressure dominates the weather pattern.

Friday-Wednesday...Conditions likely remain below SCA levels Friday into Saturday with winds out of the south to southwest as a cold front approaches from the north. This brings increasing chances for showers and storms Saturday into Sunday and possibly marine fog as well. The front looks to cross the waters either late Saturday night or Sunday with north to northeast winds possibly reaching SCA levels Sunday into Sunday night. High pressure building toward New England should then keep winds and seas below SCA levels early next week.

GYX WATCHES/WARNINGS/ADVISORIES

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