textproduct: Gray - Portland

WHAT HAS CHANGED

No significant changes at this time.

KEY MESSAGES

1. A cutoff low in the Great Lakes brings unsettled conditions into the start of the week with generally light rainfall amounts.

2. Mostly dry conditions through mid week with comfortable dew points. Humidity increases by late week ahead of another system.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

A cut off low remains in the Great Lakes region for the next few days. Moisture continues to be drawn northward into New England, while a wave of moisture passes by offshore. This brings low level moisture, sprinkles, and intermittent drizzle through the first half of the day today, especially along the Maine coast. New Hampshire sees more of the way of breaks of sun today, especially across western areas.

The warmer conditions across western NH provide more instability ahead of an approaching cold front extending from the cut off low. Given the set up, a few strong to severe storms are possible across New Hampshire today, with wind gusts and hail both a concern. The marine layer looks to limit the potential across Maine, with a gradual weakening trend expected as the storms move eastward.

The front won't pass east of the area until Monday, bringing another night of low clouds, fog, and scattered showers tonight along the coast and in Maine. Lows generally bottom out in the mid 50s to low 60s across the area, with some drier air working in behind the front across western New Hampshire by daybreak on Monday.

The front will likely be passing through Maine during the day on Monday. This brings a chance for scattered thunderstorms by midday, with a chance for a strong storm possible across parts of Central Maine. The front then clears the area by late in the day, with drier air working in late in the day.

KEY MESSAGE 2 DESCRIPTION...

Upper-level low will continue to spin through Quebec Tuesday before finally ejecting out of the area by Wednesday. Likely will have another day of diurnal clouds/brief downpours fueled by the cold pool aloft, focused in the higher terrain in the north. Dew points will remain comfortable with the westerly flow, however. On Wednesday the low loses its grip with brief height rises bringing tranquil conditions.

By late week ensembles show another wave heading our way. With a developing trough to our west, likely will see southerly flow developing and returning humidity northward. Both the GFS and ECMWF fully occlude this low in Canada, similar to the previous system. However the placement of the low has trended further north up towards Hudson Bay rather than central Quebec. If this comes to fruition, it would suggest more of a glancing blow to the trough. As such expecting forcing to be a bit more nebulous, but there will still be the potential for widespread precipitation if sufficient moisture can be advected into the region. At minimum looks like a period of more humid conditions Thurs-Fri with southerly flow developing. Temperatures are lower confidence given cloud cover and potential onshore flow, but with 850 mb temps hanging out around 13- 15 C, no signs for hot temperatures. Deterministic guidance currently suggests a chance for rain late Thurs especially across New Hampshire, but Friday will probably bring a higher chance to the entire forecast area.

AVIATION /03Z SUNDAY THROUGH THURSDAY/

Marine FG/stratus lingers through late morning to early afternoon along the coast and at Maine sites with IFR-LIFR. Valley FG is also likely through mid morning. Scattered SHRA are possible. Fog scatters out as rain showers lift across the area from west to east through the day. Some improvement to MVFR and VFR is possible by evening. TSRA is possible between 2-8PM, mainly across New Hampshire terminals. Storms will be capable of locally strong winds and possible GR. IFR to LIFR is likely along the coast and at Maine terminals again tonight with marine fog and stratus likely returning. Conditions then improve to MVFR and VFR from west to east during the day on Monday, with showers and storms possible across eastern terminals Monday afternoon.

Outlook:

Monday night: VFR conditions expected.

Tuesday: Local MVFR or lower possible in showers.

Tuesday night and Wednesday: VFR conditions expected.

Thursday: Mainly VFR but local MVFR or lower in showers late in the day.

MARINE

Conditions remain below SCA levels through Monday as a slow moving cold front approaches the waters today, and passes through on Monday. Reduced visibility in marine fog is likely through midday Monday. Fair conditions then prevail through midweek as broad high pressure builds across the waters. A cold front then approaches the waters late in the week.

GYX WATCHES/WARNINGS/ADVISORIES

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