textproduct: Gray - Portland

SYNOPSIS

Cold front pushes through this evening, bringing with it blustery conditions through Tuesday. The remainder of the week remains cold with a possible arctic front and snow shower activity New Year's Eve night. Cold temperatures and mountain snow shower activity last into the weekend.

NEAR TERM /THROUGH TONIGHT/

Impacts and Key Messages: * Gusty winds tonight pose an elevated power outage risk in areas that have seen higher end ice accumulations. * Travel may be slick again overnight as temperatures crash well below freezing.

Precipitation is still moving through the area this afternoon with the southern half of the CWA pretty much transitioned to plain rain. To the north precipitation is lighter, but falling on freezing surfaces, so caution is still needed there. Was able to trim the Winter Weather Advisories another tier inland as air and road temperatures are slowly creeping above freezing. Elsewhere, the cold air damming is holding in just like we thought it would with air temperatures stuck around 32-34F north of the foothills and right down through the Monadnock region of New Hampshire. As a result road temperatures are also stuck around 31-32F and Winter Weather Advisories will stay in place for those locations. Winter Storm Warnings will also stay in place as power outage data shows around 20,000 outages within the warning area at the time of this writing. This will only be further exacerbated as winds pick up this evening. That being said, we went ahead and issued a wind advisory to amplify the messaging that regardless of the fact that wind gusts are marginal, the additional ice load will make it easier for outages to occur. Winds pick up immediately after precipitation tapers off tonight as cold air roars back into the region behind the front. BUFKIT soundings and the latest CAMs suggest that gusts in the 25-35 mph range will be able to mix down from the fringes of a low level jet late Monday Night as the pressure gradient begins to tighten. These gusts are going to elevate the power outage threat in those areas that saw the most ice accretion on trees and power lines. On the other hand, these winds are going to help to dry out roads some before temperatures come crashing down. Travel is likely going to be slick in some spots again overnight as damp untreated roads ice back up.

SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/

Impacts and Key Messages: * Gusty winds during the day Tuesday continue to pose a power outage risk and may also delay power restoration efforts in some areas.

More frequent gusts in the 35-40 mph range are expected during the day Tuesday as the pressure gradient continues to tighten over the area. This may hamper some of the power restoration as well as pose a risk for additional outages in the hardest hit areas. Skies are going to remain on the cloudier side as we stay in the vicinity of the upper low, so temperatures aren't going to move all that much from the morning lows. It looks like areas south of the mountains rise into the upper teens and low 20s. Up north temperatures mostly remain in the single digits and low teens. Windchills end up below zero for much of the area during the day and into the night. Upslope snow showers are likely to persist in the mountains as we remain in northwest flow with the trough overhead.

Wind gusts decrease after sunset as the pressure gradient begins to relax. The upper low departs to the northeast allowing for skies to clear some. The gradient still looks tight enough for winds to remains somewhat breezy, so most locations won't completely decouple, but the fresh air mass overhead will still support a very cold night. Temperatures fall into the single digits and low teens in the southern half of the CWA, and just on the either side of zero for the northern half.

LONG TERM /WEDNESDAY THROUGH MONDAY/

* Cold air with sub-zero wind chill temperatures expected at periods through the weekend * Potential snow shower activity on New Years Eve night associated with a cold front.

Forecast Details: This period of the forecast can be summarized as broad cyclonic flow across the Northeast that will lead to a cold week with no major precipitation makers on the horizon. Model guidance is very good agreement of below normal 500mb heights over the region through the weekend. This will support below normal temperatures to start the new year with rapid ice growth on area rivers and lakes that haven't frozen over yet. One feature of interest is a shortwave trough on New Year Eve's night that will have an arctic frontal boundary associated with it. Snow shower activity will occur Wednesday night into Thursday morning and will most likely be heaviest in the mountains and along the Mid-coast. Overall light snow is expected, but could bring late night travel impacts. Cold wind chill temps to start the new year with sub-zero temperatures. Light snow showers to continue in the mountains on and off Friday into Saturday, but overall dry and cold weather is expected.

AVIATION /18Z MONDAY THROUGH SATURDAY/

Short Term...Widespread IFR/LIFR continues into the evening with gradual improvement expected as precipitation comes to an end. Conditions improve to VFR overnight tonight and prevail through Tuesday night. Westerly wind gusts increase to 25-30kts overnight tonight, lasting through the day Tuesday.

Long Term...No significant aviation weather impacts are expected on Wednesday, snow shower activity associated with a cold front could bring tempo IFR conditions Wednesday night but overall snowfall amounts look light, two exceptions could be Rockland & Whitefield where light snow is possible through early Thursday morning. Cold and breezy weather is expected into the weekend with no snow expected through this period.

MARINE

Short Term...Winds increase to Gale force tonight as a front sweeps over the waters. Gale force gusts are expected to persist through Tuesday night. During this same time period seas build to 5-9ft. Gale force gusts taper off Wednesday morning, but gusts greater than 25 kts and the elevated seas will remain.

Long Term...Broad cyclonic flow is expected through the forecast period. This will keep a persistent offshore flow across the coastal waters. This will lead to a long duration of SCA conditions from Wednesday into the weekend most likely as reinforcing shots of cold air and fronts move across the area keep things windy over the outer coastal waters.

GYX WATCHES/WARNINGS/ADVISORIES

ME...Winter Weather Advisory until 7 PM EST this evening for MEZ007>009-012>014-033. Wind Advisory from 7 PM this evening to 7 PM EST Tuesday for MEZ007>009-012>014-018>021-033. NH...Winter Weather Advisory until 7 PM EST this evening for NHZ001- 002-011-015. Wind Advisory from 7 PM this evening to 7 PM EST Tuesday for NHZ001>009. Winter Storm Warning until 7 PM EST this evening for NHZ003>009. MARINE...Gale Warning from 7 PM this evening to 7 AM EST Wednesday for ANZ150-152-154. Gale Warning from 7 PM this evening to 1 AM EST Wednesday for ANZ151-153.