textproduct: Gray - Portland

WHAT HAS CHANGED

A beautiful evening continues across most of New England with diminishing winds and a few clouds scattered around. No major changes were needed for this forecast update. Just blended in the latest observations of the sensible weather fields and freshened up the aviation forecast.

KEY MESSAGES

1. Temperatures run below normal tonight through Friday night. Sunshine Friday morning gives way to afternoon clouds and scattered showers.

2. The first half of the weekend looks wet, followed by warmer and somewhat drier conditions on Sunday.

3. Much of next week looks cooler with multiple chances for rain.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

Broad troughing over eastern North America will persist going into the weekend. Clouds that have developed this afternoon with the aid of surface heating will dissipate this evening with the setting sun. Clearing skies and light winds will allow for lows around 30F across the north and upper 30s along the coast.

Skies will start off mostly sunny Friday morning followed by building cu fields with combination of cyclonic flow aloft and surface heating. An embedded short wave will provide added lift Friday afternoon that will result in widely scattered showers with snow showers in the mountains above 3000 feet. Highs on Friday will range from 50F across the north to the low 60s along the coast. WNW winds will be breezy with gusts 20 to 25 mph during the afternoon. Friday night will be similar to tonight with lows ranging from 30F north to 40F across southern NH and coastal Maine.

KEY MESSAGE 2 DESCRIPTION... Saturday looks cool with highs generally in the 50s as clouds increase through the day. A weak area of low pressure accompanies a warm front as it lifts northward through the day, helping to enhance shower coverage. Showers look likely to reach southern New Hampshire by mid to late morning, and then slowly spread north and eastward through the afternoon hours. The coast stands the highest chance to see the rain, while northern areas toward the Canadian border are more likely to stay dry.

The rain mostly pushes off to the north and east of the area by midnight Saturday night. Mainly cloudy skies linger through the overnight, with lows generally in the upper 30s to mid 40s.

By Sunday, the area looks positioned to break into the warm sector ahead of an approaching cold front for at least a few hours. The southerly wind direction keeps the coast mainly in the 50s, while more clouds do the same across the north. Elsewhere, highs warm into the 60s with breaks of sun, and some low 70s are possible across southern New Hampshire. As the front approaches from the west during the day, scattered afternoon instability showers and an isolated thunderstorm are likely. This cold front then clears the region Sunday night, with cooler air following in behind it for early next week.

KEY MESSAGE 3 DESCRIPTION... The aforementioned cold front only slowly moves away from the coastline on Monday. A wave of low pressure develops along this front through the Mid Atlantic and rides northward through the day. At this point the bulk of the moisture looks to miss offshore, but the system looks close enough to likely bring a round of rain to at least the coastline through the day. This system remains the subject of greater uncertainty, and is likely to continue to wobble around a bit on the models over the next couple of days.

By Tuesday the front pushes far enough offshore to keep any substantial moisture away. However, a trough deepens across the Northeast, bringing a cool airmass to both the surface and aloft. Highs look to mostly top out in the 50s on Tuesday and Wednesday, with lows in the 30s at night. With the cold air aloft, pop up instability showers would be likely each afternoon after a bright start to the day.

By late in the week, moderating conditions are possible as the trough begins to weaken. However, this is far from a given as models indicate a cut off low likely develops as a weak ridge splits the trough. Anyone under the cut off low would expect to continue to see cool and showery conditions, but at this point it remains unclear whether that would be us in northern New England, or areas off to our south.

AVIATION /00Z FRIDAY THROUGH TUESDAY/

Through Friday night: Mainly VFR through the period. Winds will continue to diminish through the evening with dissipating cloud cover overnight. WNW winds will gust around 20 kts Friday afternoon with broken skies. Scattered SHRA are possible Friday afternoon while confidence in coverage is not high enough to put in the TAF. Any TAF site that sees a SHRA could see brief restrictions.

Outlook...

Saturday-Saturday night: Clouds thicken as showers spread northeastward through the day. MVFR conditions likely expand through the afternoon hours, with IFR possible along the coast. At least MVFR conditions likely linger at most terminal Saturday night.

Sunday: Improvement to VFR is likely through the morning, and then scattered showers are possible in the afternoon and evening.

Sunday Night-Monday: MVFR is possible along the coast with periods of light rain, while VFR conditions are more likely inland.

Tuesday-Wednesday: VFR likely prevails, but brief restrictions with afternoon showers will be possible each day.

MARINE

Winds and seas remain below SCA thresholds tonight through Friday night. Offshore winds tonight shift out of the SW with gusts to 20 kts Friday afternoon followed by diminishing winds Friday night.

SCA conditions are possible ahead of a cold front Saturday night and Sunday. The front then slowly crosses the waters on Monday. Low pressure likely tracks well east of the Gulf of Maine on Tuesday. Broad high pressure gradually builds across the waters through midweek.

GYX WATCHES/WARNINGS/ADVISORIES

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