textproduct: Gray - Portland

WHAT HAS CHANGED

For forecast is generally evolving as expected. No major changes.

KEY MESSAGES

1. Wet weather continues on and off through Memorial Day. An isolated thunderstorm is possible late tonight or early Memorial Day across portions of coastal/interior Maine.

2. A fairly unsettled but unimpactful 2nd half of the week is expected, with cooler temperatures and scattered showers likely.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

The initial push of light to moderate rain continues to spread across the forecast area from southwest to northeast this afternoon but we could see a little bit of a break/dry slotting later in the afternoon or evening before the main wave pushes through overnight/Monday morning. RAP soundings indicate that we could see some pockets of MUCAPE around 100 J/kg or so tonight and early Monday over coastal Maine and portions of the interior. Thus, have included mention of isolated thunder here.

Rain should move out of the forecast area gradually from west to east Monday late morning/early afternoon, but a few showers could linger, especially in the mountains. Storm totals have come in a bit higher in general across all of New Hampshire and western Maine as we could see some heavier rain tonight into Monday under convection, generally a half inch to an inch with locally higher amounts possible along the coast.

Regarding temperatures, it will remain cool today with highs mainly in the 50s. Tonight's lows will mainly dip into the low to mid 40s with a few upper 40s possible along the coast and a few upper 30s in the mountains. Highs should recover nicely on Monday, especially south of the mountains were we should see widespread values in the mid 60s to the mid 70s. The mountains will see highs in the mid 50s to the mid 60s. Monday night lows are forecast to range from the upper 40s to the lower 50s.

KEY MESSAGE 2 DESCRIPTION... Through the 2nd half of next week, a 500mb ridge builds in the central US. The amplification of this ridge is likely to push an upper-level low southward into the Canadian Maritimes. This will allow for an unsettled and cooler end of next week.

Wednesday morning, a surface low moves southeastward across the region. Instability exists with minimal energy and an early frontal passage time should allow for more showery weather across the area rather than thunderstorm activity. The cold front moves across by the end of the day, allowing for even cooler temperatures to arrive on Thursday. Temperatures on Wednesday will range from lower 70s in the north, to low to mid 80s across southern NH.

Just like Wednesday, some instability may also exist on Thursday but temperatures will be too cold to generate enough diurnal heating to produce convection. Thursday should start dry but become more unsettled by the end of the day. Thus, more showery and rainy weather is likely Thursday evening with rain chances a bit higher over Maine. Showery conditions look to continue into the weekend. High temperatures look to be in the mid-60s along the coast through the remainder of the week, near 70F elsewhere.

AVIATION /00Z MONDAY THROUGH FRIDAY/

The full range of flight categories exists currently across the forecast area as showers continue to slowly drift eastward. VFR conditions still currently in place across eastern parts of the forecast area as well as north of the mtns. While IFR and lower CIGs and occasionally low VIS have crept into portions of southeastern and central parts of the forecast area. The general expectation is for that to expand up to the southeast slopes of the mtns thru the overnight so that widespread IFR or lower exists. Some fog may develop near the coast even as the threat of showers diminishes overnight. I can't rule out a rumble of thunder as more rain/showers develop after midnight, but confidence is low enough to not include in the TAFs at this time. After that rainfall moves thru the area we will see gradual improvement early to mid afternoon on Monday but some MVFR CIGs will likely hang around. By late afternoon, most sites should improve to VFR categories but some lingering MVFR is possible in the mountains, potentially impacting HIE.

OUTLOOK:

Monday night: VFR conditions expected.

Tuesday: VFR conditions expected.

Tuesday night: MVFR possible in the mountains with showers and isolated thunder.

Wednesday: MVFR possible due to showers and possible thunder.

Wednesday night: MVFR possible due to showers.

Thursday: MVFR possible due to showers, mainly in the mountains.

Thursday night: MVFR possible due to showers.

Friday: MVFR possible due to showers.

Friday night: MVFR possible due to showers.

MARINE

High pressure continues its slow retreat today and southeast or east southeast winds will slowly increase overnight into Monday. While wind gusts will generally stay below 25 kt for most of the waters, seas are forecast to build into the 5 to 7 foot range Monday. Current forecasts are for periods to be in the high single digits, so seas may approach high surf advisory criteria.

Generally relatively light winds are expected Tuesday through the remainder of next week. Seas of 3-6ft are expected Tuesday morning, but will decrease to 2-4ft by Wednesday morning. Seas of 2-4ft expected beyond Wednesday.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...Small Craft Advisory from 2 AM Monday to 8 AM EDT Tuesday for ANZ150-152-154.