textproduct: Gray - Portland

SYNOPSIS

A coastal storm passes well out to sea tonight into Sunday but may be close enough for a little light snow along the coast and over southern New Hampshire. That will be followed up by another very cold Monday with gusty winds. Expect the wind chills to remain in the teens and single digits.

NEAR TERM /THROUGH TODAY/

Winds continue to ease through the overnight hours as a ridge axis of high pressure builds in from the west. Winds likely dont go completely calm in most spots until near sunrise, if at all. At the same time, clouds begin to overspread from the west, which limits the radiational cooling effects through daybreak.

During the daytime today, an elongated shortwave pivots through northern New England around a more broad trough. This brings just enough instability and moisture to bring some intermittent snow showers during the late morning and afternoon hours. A little bit more moisture feeds into the MidCoast off the ocean, so a steadier burst of light snow may bring up to about a half inch here. Other than similarly light accumulations across the higher terrain, no accumulation is expected elsewhere.

SHORT TERM /TONIGHT THROUGH SUNDAY/

An Alberta Clipper slides south of New England tonight and tomorrow, and begins to develop into a strong ocean storm as it moves out to sea. Clouds from this developing system keeps temps warmer tonight, with lows mainly in the teens to low 20s.

Along the coast, just enough moisture may extend from the western edge of the developing system to bring some periods of light snow along the coastal plain late tonight and tomorrow. Accumulations would remain very light, with little more than a coating expected. There is also a decent chance that this moisture remains entirely offshore, so we'll have to monitor just how far west the moisture actually extends as the system is developing.

As the system continues to move out to sea and strengthen, an increasing northerly wind develops for the afternoon and evening hours tomorrow. The next shot of cold air begins to move in on this northerly wind tomorrow, with highs topping out in the 20s to near 30. Temps steadily fall during the afternoon hours as the CAA increases.

LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/

The next shot of arctic air pushes in overnight Sunday, leading to frigid temperatures Monday morning and blustery conditions through the day. Lows are forecast to mainly range from around zero across portions of the north, to the upper single digits and lower teens south. Strengthening westerly winds will lead to widespread below zero wind chills Monday morning with some double digit readings below zero across the north. Some low probability snow chances may hang around into Monday morning near the coast and through the day across the mountains in the upslope regime.

It should stay cold and windy through the day on Monday with highs only rising into the upper single digits across portions of the north, to the lower 20s south. With winds remaining gusty through the day, wind chill values will likely remain below zero north and only rise into the single digits above most elsewhere.

Tuesday morning lows will be very similar to Monday 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 30 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 night. Low chances of light snow are possible Monday night with low chances of light rain or snow mid-week. A stronger system with more widespread chances of precipitation looks possible to end the work week but details remain unclear this far out.

AVIATION /06Z SATURDAY THROUGH WEDNESDAY/

Short Term...MVFR ceilings linger at HIE through at least tonight. Light snow showers are possible at all terminals late this morning and afternoon, but would likely only bring brief MVFR restrictions. Light snow and MVFR conditions are possible again across coastal terminals late tonight and Sunday morning.

Long Term...A few lingering snow showers could lead to some MVFR conditions for a few sites Sunday night into Monday morning. Otherwise, expect VFR conditions through Monday aside from upslope snow showers around HIE. Another couple of weak systems may bring light precipitation to parts of the region Monday night and again on Wednesday, but widespread restrictions look unlikely.

MARINE

Short Term...SCA conditions ease through daybreak. Another period of SCA conditions is likely this afternoon and tonight across the outer waters in southwesterly flow. A developing ocean storm tracks south of the Gulf of Maine tomorrow, with northerly winds increasing to SCA levels by tomorrow afternoon.

Long Term...SCA conditions are likely late Sunday through Monday. Northwest winds increase as the low deepens over the Canadian Maritimes and there may also be a period of gales. Conditions improve Tuesday before a cold front approaches and crosses mid week, likely bring at least SCA conditions and possibly gales. Another frontal system is then possible late in the week.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...Small Craft Advisory until 4 AM EST Saturday for ANZ150-152- 154.