textproduct: Gray - Portland

WHAT HAS CHANGED

Little change to the going forecast today.

KEY MESSAGES

1. Dry weather continues through Friday with lighter winds. Cold temperatures tonight and early Saturday morning may allow for patchy frost development in northern zones.

2. Rain showers are expected Saturday night into Sunday morning, especially across southern zones. Mainly dry weather is then expected once again to start the work week.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

Dry weather is expected today with lighter winds. Still, the pressure gradient with support 20 to perhaps 25 MPH gusts at times. It will be cooler than yesterday, with highs mainly in the 70s with low humidity.

High pressure begins to move in from the west tonight which will mean decoupling in the low levels, especially western and northern zones. This will lead to chilly overnight lows, with readings dipping into the mid to upper 30s in the northern zones, with 40s most elsewhere.

High pressure pushes off to our east on Saturday with return flow allowing for southerly SFC winds and widespread 70s for highs. High clouds may increase late in the day.

KEY MESSAGE 2 DESCRIPTION...

Showers are expected Saturday night and into Sunday, as a cold front moves eastward across the area. Ahead of the front, the convective environment is meek, with conditional instability through much of the thermal profile. Ensembles have been hinting at showers that produce more meaningful rainfall Saturday night given that PWATs are in the 90-95th percentile there. Once these showers pass however, PWATs will drop significantly as the cold front pushes eastward. So any showers that develop along the passing cold front on Sunday should be much drier and produce lesser rainfall amounts. As it stands now, it is likely that most people see a little rain Saturday night and into Sunday. Southern NH should see more rainfall than the rest of NH and western Maine.

After the cold front passes, high pressure moves in and will allow for fair and crisp fall weather on Monday and Tuesday. Highs look to be in the lower 70s.

With high pressure overhead, Monday night also looks to be clear and feature a period of calmer winds. This could allow for radiational cooling and cold low temperatures, with areas north of the mountains potentially breaking 40F Tuesday morning.

AVIATION /12Z FRIDAY THROUGH TUESDAY/

Any lingering valley fog clears from LEB by mid morning. VFR conditions continue today with northwesterly wind gusts 15-20 kts at most terminals. This should be strong enough to keep the seabreeze offshore. Valley fog is likely tonight. On Saturday, VFR conditions continue with relatively light southerly SFC winds.

Outlook:

Saturday Night-Sunday: MVFR possible, especially at NH terminals in showers, mostly through Sunday morning.

Sunday night-Monday: Generally VFR.

Tuesday: VFR expected.

MARINE

High pressure nears today and moves across the waters Saturday. This keeps conditions below SCA criteria. Wind direction will remain steady offshore today and southerly on Saturday.

Conditions should remain below SCA thresholds for the most part through Tuesday.

GYX WATCHES/WARNINGS/ADVISORIES

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