textproduct: Gray - Portland

WHAT HAS CHANGED

No significant changes with this forecast update.

KEY MESSAGES

1. Scattered showers and thunderstorms Sunday with lighter winds.

2. Low pressure moves in late Monday into Tuesday, bringing a soaking rain to New England. Weather remains unsettled through the remainder of next week.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

Vertically stack low pressure system will pull northeast away from the area tonight into Sunday allowing gusty winds to subside. On Sunday, cooling temperatures aloft combined with higher dewpoints than today will yield 1000-1200 J/kg of SB CAPE by early afternoon. While a weak wave will be crossing late morning, short wave ridging will attempt to build in from the west during the afternoon limiting support for ascent. Surface heating should allow for cu fields to blossom late morning with CAMs showing instability driven showers and storms developing early afternoon. Coverage will be more widespread than today while many areas stand to finish the day without measurable rainfall. Shear will be next to non-existent limiting the threat for organized convection, with more in the way of pulse storms expected. Relatively steep mid level lapse rates and freezing levels below 10kFT may allow for stronger cells to produce hail. Steep low level lapse rates may allow for gusty outflow winds with any core collapses. Convection will wane with the loss of heating during the evening. Highs on Sunday will range from the upper 60s north to upper 70s south.

KEY MESSAGE 2 DESCRIPTION...

A relatively zonal mid-level pattern is likely through the remainder of next week. This will allow for the potential to see multiple low pressure systems move across northern New England.

From Monday afternoon into Tuesday, decaying low pressure from the Ohio River valley will arrive in New England, bringing meaningful rainfall to the area. PWATs look to be near the 75th percentile, which could allow for a more soaking rain but flooding of any kind looks unlikely at the moment. With the center of low tracking along the Gulf of Maine, rainfall amounts are likely to the highest south of the mountains. Ensemble probabilities show a 55% chance this area gets more than 1 inch of rain. Locations north of the mountains could see up to a half inch or so.

Through the second half of the week, instability over the area is likely to generate scattered showers and thunderstorms. Temperatures also look a little warmer, with high temperatures in the upper 70s and lower 80s through the rest of the week. Wednesday has the best chance to be the driest day of the three, with scattered thunderstorms appearing more likely for Thursday and Friday.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

Through Sunday night: Gusty winds will diminish around 00Z this evening. Mainly VFR tonight, while patchy fog cannot be ruled out at LEB and HIE. Mainly VFR Sunday with scattered TSRA developing around 18Z and last until around 00Z. Scattered TSRA will bring the potential for localized restrictions. Depending on rainfall Sunday some patchy fog may be possible Sunday night. Otherwise, VFR.

Outlook:

Monday: AM VFR, MVFR in the evening due to rain and thunderstorms.

Tuesday: AM MVFR, improving to VFR by the end of the day.

Wednesday: VFR likely.

Thursday-Friday: MVFR likely due to showers and thunderstorms.

MARINE

Gusty offshore winds will diminish this evening. Winds and seas will remain below SCA thresholds Sunday into Sunday night.

Light, variable winds and seas of around 2-4ft are expected through all of next week. One potential exception to this may be late Monday into Tuesday. This is due to low pressure moving across the area, and some southeasterly SCA gusts are possible especially over the open waters. Seas also could be a little bit elevated on Tuesday as well, with occasional 3-5ft seas possible as well. Conditions return to baseline by the end of the day Tuesday.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...Small Craft Advisory until 7 PM EDT this evening for ANZ153.