textproduct: Gray - Portland

SYNOPSIS

A weak area of low pressure will bring some light snow to southern areas through this morning. Another shot of cold air builds into the region Monday. A couple of weak disturbances bring chances for snow showers Monday night and again Wednesday. Temperatures will warm above normal the second half of the week as an area of low pressure tracks northwest of New England.

NEAR TERM /UNTIL 6 PM THIS EVENING/

645 AM Update...Light snow continues to stream northeastward across southern NH northeastward to the Maine coastal plain. The northern NH mountains are getting into it as well. While the snow is light in intensity there are occasional transient bands that are efficient accumulators. Have increased snow amounts by a half inch to one inch in some areas just inland front the coast as well as portions of southern NH. Roads will be slippery.

Previously...

A weak area of low pressure will pass southeast of Nantucket this morning as an H5 s/wv trof swings east across New England while becoming negatively tilted. A sfc trof is progged to develop near the ME coast this morning in response to the passing s/wv, and this should allow for some light snow across much of southwestern ME south of the foothills as well as NH, mainly from the Lakes Region and points south.

Forecast soundings show a nearly saturated -12C to -18C layer with decent cross hair omega within this layer for a few hours across these locations. Despite low QPF of generally a tenth of an inch or less, snow- liquid ratios (SLRs) of between 12-15:1 will likely allow for some southern locations to receive between 1-2" of snow with perhaps some locally higher amounts. Given the cold antecedent airmass and road temperatures, this could result in locally slippery travel today.

Any lingering light snow will move offshore by early this evening with some clearing developing behind it. High temperatures will remain cool with readings into the 20s/lower 30s. Northwesterly winds will also increase late in the day with gusts up to ~25 mph, which will make it feel colder.

SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/

Tonight will be blustery with gusty northwesterly winds continuing and lows falling into the single digits and lower teens. Some upslope snow is possible across the mtns and towards the Canadian Border.

On Monday H8s will fall to around -15C, which despite a good amount of sunshine will limit high temperatures to the teens and 20s from north to south. Windchill values will be into the single digits either side of zero.

LONG TERM /MONDAY NIGHT THROUGH SATURDAY/

Monday night/Tuesday morning lows will be very similar to Monday morning lows but with less wind. The warmup then begins in earnest on Tuesday afternoon as highs rise into upper teens and lower 20s north, to the upper 20s and lower 30s south. By Thursday, the NBM has forecast highs ranging from the low to mid 30s north, to the low to mid 40s south. There are also some signals in the long term ensembles that these warmer temperatures could extend into Friday and the weekend.

Regarding precipitation chances, a couple of weak shortwave troughs will approach on Monday night and again Wednesday. Low chances of light snow are possible Monday night with low chances of light rain or snow mid-week. A stronger (but progressive) system with more widespread chances of precipitation looks possible Thursday/Friday but details remain unclear this far out. As of now, impact would likely be minimal given the progressive nature.

AVIATION /12Z SUNDAY THROUGH THURSDAY/

Short Term...-SN will likely result in MVFR/IFR restrictions at times between 04Z-18Z today. Conditions will improve later Sunday with gusty NW winds developing. Some gusts up to 25 kts are possible. VFR conditions will then prevail Sunday night through at least Monday.

Long Term...Outside of snow showers at KHIE Monday night and again Wednesday, conditions will mainly be VFR into Thursday morning. Low pressure brings potential for restrictions late Thursday through Thursday night.

MARINE

Short Term...Gale force NW winds are possible tonight into Monday morning behind a cold front. Seas will build to 1-3 ft in the bays with 3-5 ft across the outer waters. Light freezing spray is also possible tonight as much colder air arrives.

Long Term...NW winds will gust to 30 kts Monday into Monday night. Winds and seas drop below SCA thresholds Tuesday. SW winds increase Tuesday night through Wednesday and may approach Gale force Wednesday as low pressure passes north of New England. Winds briefly turn offshore Wednesday night into Thursday morning before increasing out of the south late Thursday ahead of the next low pressure system.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...Gale Watch from this evening through Monday afternoon for ANZ150-152-154. Small Craft Advisory from 2 PM this afternoon to 3 PM EST Monday for ANZ151-153.