textproduct: Gray - Portland

WHAT HAS CHANGED

Most of the lightning and small hail activity has subsided as we approach sunset, but scattered showers will likely continue through the night. No major changes were needed for this update.

KEY MESSAGES

1. Low pressure brings showers and storms into the overnight hours tonight.

2. Some scattered showers remain possible on Monday, with highs generally in the 60s.

3. A warmup and mainly dry weather is expected Tue-Fri.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

Another low pressure system dives southward into New England through the afternoon today and tonight. This one won't be as organized or as strong as the one yesterday, but it brings with it widespread showers and thunderstorms. These continue to increase in coverage through the afternoon hours as colder air moves in aloft. This colder air aloft also increases the chance for heavier showers and storms to contain small hail, and bring some gusty winds at times.

The coverage of the showers and storms decreases overnight, but are likely to continue through the overnight hours near the low pressure center. This center is expected to pivot through southern Maine, and then slip offshore by the morning hours on Monday.

KEY MESSAGE 2 DESCRIPTION...

As the low moves away, a period of relatively drier conditions moves in for Monday. However, with cold air aloft following the low, isolated pop up showers will be possible again by the afternoon hours on Monday. Cool Canadian air follows the low, yielding highs in the 60s across most of Northern New England. Even where the most sunshine holds on through the day, mid 60s look like the high end for temps tomorrow.

Skies clear tomorrow night as drier air moves in. This brings another seasonably cool night, with lows dropping into the upper 30s to low 40s. A small area of high pressure passes through early in the overnight. With all the recent rainfall, some patchy fog will be possible tomorrow night through the valleys. Clouds then increase toward morning as a weak trough pivots in from the north.

KEY MESSAGE 3 DESCRIPTION...

The upper level troughing will lessen Tuesday as it gradually gets replaced by short wave ridging by later in the day. This should lessen coverage of diurnal showers and allow for warmer weather. However, lingering cold air aloft working in tandem with weak low level convergence should allow for widely scattered showers and perhaps isolated thunderstorms during the afternoon, especially on the coastal plain.

Overhead ridging with further strengthen on Wednesday and Thursday with dry weather and highs in the 70s on Wednesday and 80s on Thursday.

Chances for showers increase some late Friday as a cold front may begin to sag southward out of Canada. However, mainly dry weather is expected with summer-like highs well into the 80s. The threat may continue into Sunday depending on frontal position.

AVIATION /00Z MONDAY THROUGH FRIDAY/

Ceilings will mainly be in MVFR categories at most terminals through the evening with scattered showers. Ceilings likely fall to IFR at most terminals overnight, and then MVFR to VFR returns with clearing skies Monday morning. Scattered showers are possible tomorrow afternoon. VFR prevails tomorrow night, but some valley fog is possible.

Outlook:

Tuesday: VFR with isolated showers possible on the coastal plain in the afternoon. Light north winds becoming southerly on the coastal plain during the afternoon.

Tuesday night: VFR expected.

Wednesday/Wednesday night: VFR with light winds.

Thursday/Friday: High pressure is favored with VFR conditions.

MARINE

Conditions remain below SCA levels through Monday night. A weak low pressure system tracks southeastward through the Gulf of Maine late tonight and Monday morning. A small high pressure system passes through tomorrow night.

Fair weather Tue-Fri with winds and seas remaining below SCA thresholds.

GYX WATCHES/WARNINGS/ADVISORIES

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