textproduct: Gray - Portland

WHAT HAS CHANGED

No major changes were needed for this forecast package. A beautiful afternoon continues across the region.

KEY MESSAGES

1. Dry weather continues through Thursday with warming temperatures.

2. Warm temperatures expected Friday before a cold front brings a chance of showers Friday night and slightly cooler but still above normal temperatures over the weekend.

3. Even warmer temperatures are possible early next week ahead but will come with chances for rain showers.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

High pressure is dominating the weather pattern over New England this afternoon. The high will slide off into the waters this evening and an upper ridge axis moves across the region overnight. This should lead to optimal radiational cooling conditions under a clear sky and calm winds. Thus, we trended more towards the NBM 10th percentile for lows tonight, ranging from the low to mid teens north, to the low to mid 20s south.

On Thursday, we will transition back to southwest flow aloft as the next trough starts to approach. A cold front will also start it's approach which will lead to a tightening pressure gradient and gusty southerly winds through the day. Sustained values will mainly be in the 10 to 15 mph range outside of the higher terrain (where we could see readings more in the 20 to 25 mph range). Gusts will mainly be in the 25 to 30 mph range. The atmosphere will also remain fairly dry on Thursday outside of coastal areas which may see a dewpoint bump with the return flow. Outside of the coast in western Maine, afternoon relative humidity will dip into the 20 to 30 percent range. Much of New Hampshire will be even drier with widespread minimum humidity values in the 20 to 25 percent range. Some readings in the upper teens are not out of the question over southern New Hampshire. The warmup also continues on Thursday with highs forecast to range from the upper 40s and lower 50s north, to the mid to upper 50s over southern New Hampshire, and mainly in the lower 50s across coastal and interior Maine.

KEY MESSAGE 2 DESCRIPTION...

Friday will be even warmer than Thursday as southwesterly flow continues to bring warmer air into the region ahead of a cold front. New Hampshire and interior western ME are expected to climb well into the 50s and 60s, but the cooler locations will be along and closer to the coast, especially from near Portland to Rockland where the onshore flow could hold temps in the 40s to lower 50s.

The cold front crosses northern New England Friday night, bringing a round of rain showers along with it. Rainfall amounts are expected to be light and mostly in the 0.10" to 0.25" range with most of the precip ending by sunrise Saturday.

Temperatures come down a bit behind the front on Saturday but will still be near or just above normal with most in the seeing highs in the 50s with mostly-partly sunny skies. The exception will be the mountains where more clouds and a chance for rain and snow showers will keep temps in the 40s. It will also be breezy with gusts of 25 to 30 mph based on forecast soundings, but these will dimninish toward sunset as we lose daytime mixing and high pressure builds more overhead. Dry conditions continue into Sunday, but the high will begin to shift to the south and east as a front approaches. High temperatures will again be mostly in the 50s, and the WAA may bring parts of southern NH closer to 60 degrees.

KEY MESSAGE 3 DESCRIPTION...

As mentioned earlier, a frontal boundary enters the picture early next week as low pressure passes near or just north of the Great Lakes and eventually into the Canadian Maritimes. We could see a couple of very warm days as this front looks to remain north of the area for at least Monday and possibly Tuesday before it potentially crosses into or even south of northern New England Wednesday. At the same time, multiple waves aloft could bring rounds of showers and more cloudiness, which could hinder warming to an extent.

There remains a decent spread in temperature guidance, so it's still uncertain how warm we will actually get. However, the encouraging news is that even the NBM 10th percentile would result in above normal temps, and even the 25th percentile is a fair amount warmer than that. As of right now, Tuesday looks to be the warmer of the days, but that can certainly change.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

VFR expected through at least Thursday. We could have some stratus or marine fog develop Thursday night near the coast, but otherwise VFR. While winds will be light and variable the rest of today and tonight, they will be on the increase on Thursday. Southerly winds will become a bit breezy in the afternoon with gusts up to 25 knots possible.

Outlook...

Friday: Low stratus or fog may occur near the coast at times with the higher potential for RKD. Otherwise VFR.

Friday night: MVFR to IFR restrictions possible as a cold front brings a chance of rain showers and perhaps fog and low stratus outside of precipitation.

Saturday-Sunday: VFR expected, except MVFR cigs possible at HIE on Saturday.

Monday: Restrictions possible with a chance for rain showers.

MARINE

Conditions remain below SCA thresholds until Thursday when southerly flow increases and some 25 kt gusts return. Thursday into Thursday night will have to watch for marine fog/stratus formation as moisture returns northward.

Friday-Wednesday...SCA conditions possible as a cold front approaches and crosses Friday into Friday night. There may also continue to be marine fog and stratus until the front passes. High pressure builds across the waters over the weekend, and then SCA conditions are possible as south to southwest flow increases late Sunday into Monday with the high shifting to the south and east and a frontal boundary approaching from the north and west. The front may move toward or into the waters Tuesday or Wednesday of next week with more SCA conditions possible.

GYX WATCHES/WARNINGS/ADVISORIES

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