textproduct: Gray - Portland

SYNOPSIS

Temperatures remain below normal through Monday. Some light snow is possible again Monday afternoon into Monday night as another clipper system crosses. A warming trend builds into the Northeast US mid to late week. A better chance for more widespread wintry precip comes Tuesday evening and Wednesday.

NEAR TERM /UNTIL 6 AM MONDAY MORNING/

830pm Update...Temperatures are cooling, but at a slower rate due to clouds pushing across the area. Have moderated temps through the evening as a result, but still foresee a good window of radiational cooling after midnight.

Previous Discussion... High pressure approaches from the west this afternoon and will allow for clearing skies across the region. Skies should go near completely clear overnight, and winds will gradually calm this evening and through the overnight hours. Fresh snow, calm winds, clear skies and persistent cold air advection through this afternoon will allow for substantial radiational cooling tonight. Lows are expected to drop to near -20F across valley locations north of the mountains. Outside of this area, lows are expected to range from around -15F in the foothills to near 0F in Manchester and across southeastern NH. For this reason, I opted to issue Cold Weather Advisories across the northern tier of NH and western ME. Wind chills are likely to be below zero everywhere by Monday morning.

SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/

Monday will start off as a very cold but mostly tranquil day, with increasing cloudiness through the day. Temperatures should be able to rebound somewhat quickly, with highs in the teens up north and lower 20s across southern NH. A clipper moves over southern New England Monday evening and is expected to put down a quick inch or two of snow across southern NH. However, a coating is possible anywhere south of the mountains. Low temperatures will also struggle to bottom out tomorrow night with the clouds overhead. This will allow for a much warmer night Monday night than tonight, with lows ranging from single digits above 0F north of the mountains all the way to upper teens in southern NH.

LONG TERM /TUESDAY THROUGH SUNDAY/

Key messages:

-Widespread light snow remains likely Tuesday night into Wednesday with mixed wintry precipitation possible. Slippery travel is likely, especially for the Wednesday morning commute.

-The pattern will remain active with additional precipitation possible Friday night into Saturday.

-Above normal temperatures are possible Thursday through the upcoming weekend.

The clipper system will continue pushing east Tuesday, but lingering low-level moisture will keep skies cloudy for the most part, especially south of the mountains. Forecast soundings do also suggest the possibility of freezing drizzle Tuesday morning, which will be something to keep an eye on. The rest of the daytime hours should remain dry with temperatures in the mid 20s to low 30s.

Widespread precipitation is still on track Tuesday evening into at least Wednesday afternoon, but fortunately it looks to arrive after the Tuesday evening commute. However, slippery travel is looking likely for the Wednesday morning commute with a variety of precip types possible. This is owed to a shortwave trough quickly crossing the Great Lakes with surface low trekking toward New England Tuesday night and a secondary low developing near the coast on Wednesday. Initially, forecast soundings show precip as snow Tuesday evening into the first part of Tuesday night. As the night goes on and into Wednesday morning, surface temperatures for the most part are expected to remain subfreezing with CAD in place, but warming temperatures aloft may lead to a period of freezing rain and or sleet, especially from the foothills southward. The models have trended faster with this system, and precip is expected to gradually end Wednesday afternoon and evening, although some impacts to the evening commute are still possible.

Other than lingering upslope precip Wednesday night into Thursday, building high pressure will bring dry conditions and warmer temps...with highs climbing to the mid 30s to lower 40s.

Above normal temperatures are likely to continue into Friday, and possibly Saturday as a well, but that depends on the evolution and track of any upcoming low pressure system(s). There is a good signal for another chance at widespread precip as early as Friday or more Friday night and Saturday, but confidence in details is low. Some ensemble solutions are warmer with more a northerly low track while some are colder and farther south or in between. So rain and snow and even a wintry mix are possible at this point. Whatever ends up happening, the system may be past by Sunday to bring a drying trend to finish up the weekend.

AVIATION /01Z MONDAY THROUGH FRIDAY/

Short Term...VFR expected through Monday morning. A disturbance will bring thickening and lowering clouds Monday afternoon west to east with SN. This will lower ceilings to MVFR for most terminals south of WVL to BML, with MVFR to IFR vis for these locations Mon afternoon through Mon evening.

Long Term...Can't completely rule out a brief period of freezing drizzle Tuesday morning, but otherwise MVFR to IFR ceilings may hold on through at least part of Tuesday. Widespread restrictions then become likely Tuesday evening through at least Wednesday afternoon as low pressure moves across New England. Snow is expected in the mountains, but southern and coastal terminals could see all precipitation types with this system. Conditions should improvement Wednesday evening into Wednesday night with VFR for Thursday, except the usual lingering restrictions at HIE. Another system could bring more restrictions to the region Friday and/or Saturday.

MARINE

Short Term...SCA northwesterly winds expected through the night. Combined with cold temperatures, light to moderate freezing spray is expected. Winds diminish Monday morning, with light and variable winds expected Monday afternoon through Tuesday morning. Seas of 1-3ft expected this afternoon through Tuesday morning.

Long Term...Low pressure including a weak secondary low developing near the coast will bring mostly rain to the waters Tuesday night into Wednesday, but there may be a period of mixed precipitation closer to the coast and bays. SCA conditions are also possible, especially late Wednesday into Wednesday night once winds turn W-NW as the low lifts into the Maritimes. High pressure builds in for Thursday before another system approaches either Friday or Saturday.

GYX WATCHES/WARNINGS/ADVISORIES

ME...Cold Weather Advisory until 9 AM EST Monday for MEZ007>009- 012>014-033. NH...Cold Weather Advisory until 9 AM EST Monday for NHZ001>006. MARINE...Small Craft Advisory until 7 AM EST Monday for ANZ150-152-154. Freezing Spray Advisory until 7 AM EST Monday for ANZ150-151.