textproduct: Gray - Portland

SYNOPSIS

An upper level disturbance will cross New England on Friday bringing a round of snow showers and potential squalls, especially in the mountains. After high pressure quickly moves near the region Saturday into Saturday night, low pressure will draw moisture and precipitation back into the region Sunday. High pressure then tracks through New England Monday and Monday night.

NEAR TERM /THROUGH TONIGHT/

Quiet weather continues on this Thanksgiving Day with a surface ridge over the area. Winds will gust upwards of 25 mph over the next few hours and then will ease around 4 PM as the sun goes down.

For tonight, skies will be mostly clear to partly cloudy with seasonably cool temperatures in the 20s for overnight lows. A shortwave trough stemming from an upper low in Quebec will approach late and may result in a few snow showers in the mountains toward daybreak.

SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/

The upper-low will slowly move to the east across Quebec and send a pretty vigorous shortwave through New England Friday morning and afternoon. This will not only get snow showers going in the mountains but will also increase chances for snow showers outside the mountains as Froude numbers from the NAM and GFS show flow becoming unblocked/supercritical through the course of the morning and afternoon. Based forecast soundings depicting steep low-level lapse rates, upwards of 100 J/kg of MUCAPE, and sufficient moisture, there's potential for some of the snow showers to be heavy with a few snow squalls also possible, which could even make it all the way to the coast.

Outside of snow showers/squalls, expect partly to mostly cloudy skies south of the mountains with blustery conditions as gusty westerly winds will keep wind chills in the 20s. Based on forecast soundings, looks like gusts will be generally in the 25 to 35 mph range with a few over 40 mph on the higher end.

Snow showers will wind down south of the mountains as we lose daylight and as the shortwave crosses to the east. The mountains will stay mostly cloudy with snow showers continuing through Friday night as flow and moisture will remain conducive for upslope precipitation. There may continue to be a bit of spill over into the foothills as Froudes remain above 1 but not as high as during the day Friday. It will be chilly night as temperatures drop into the 20s, but with it remaining breezy, wind chills will be in the 10s, possibly single digits across the north.

LONG TERM /SATURDAY THROUGH THURSDAY/

Key Messages: * Blustery yet again Saturday with gusts 20 to 35 mph. These weaken during the afternoon with light winds by the evening. * Quick moving system through the Great Lakes and Quebec brings next chance of rain and snow Sunday. * Active pattern continues with low pressure tracking into the Gulf of Maine Tuesday into Wednesday. Uncertainty remains with placement of the low and resulting precipitation amounts/types.

Details: The region will still be under a tight pressure gradient Saturday as low pressure pulls north and high pressure follows north from the Mid-Atlantic. The channeled NW flow will make for another blustery and cool day with highs in the mid 20s to upper 30s. Exiting wind field slackens afternoon, but the morning will be capable of gusts 20-35 mph, especially once daytime mixing picks up.

After noontime, ridging works its way into the Northeast and gradient winds subside. After a blustery start, the evening will trend quite calm with little to no breeze after sunset. While clouds will be thickening ahead of next weather system Sunday, there may be a window of good radiational cooling in the evening to midnight hour. This could lower minimum temps Sat night from the going forecast which calls for teens to lower 20s.

Next system arrives during the day Sunday featuring a wintry start with trend towards rain for the coast and some of the interior. Cold air will be entrenched ahead of the low as it tracks through the Great Lakes and into Quebec. However, the escaping high pres to the east and low to the west will open WAA into the coast. Temps here may rise into the upper 30s to around 40 before more steady precipitation arrives later. Thus accumulating snow on the coast remains unlikely. Further inland, particularly the mountains, snow is more likely for duration of the event. Question here will be how well the warmer air percolates into the valleys. This may result in a more elevation dependent accumulation event in the northwestern CWA. While the system is progressive, model guidance is pretty agreeable that greatest precip rates occur during the Sunday afternoon timeframe. Precip ends west to east, with some lighter mtn snow showers continuing overnight.

Active pattern continues into next week as high pressure quickly tracks through on Monday/Mon night, followed by the next system Tuesday into Wednesday. This one has been turning heads as recent deterministic guidance brings strong low pressure into the Gulf of Maine. At this range, there is still a lot of jockeying with the low's track, but consensus has been to include much of the CWA on the cool side, including the coast. Strength of the system will bear watching, should the low track through the western Gulf, accumulating snow would be in the forecast for most points in the forecast area. In addition to placement, pace will also dictate any potential impacts this system may bring.

AVIATION /18Z THURSDAY THROUGH TUESDAY/

Short Term...Expecting prevailing VFR through most of tonight before chances of MVFR ceilings and snow showers increase at HIE and LEB Friday morning and afternoon with IFR visibilities possible at times. These will likely continue at HIE through Friday night. For the rest of the TAF sites, scattered snow showers may produce brief IFR conditions during the day Friday, but these chances will decrease around sunset (~21Z Fri).

For winds, expect gusts around 20 kt through around 21Z before easing this evening. Friday will be breezier with westerly gusts 25- 30 kt, possibly up to 35 kt, during the day.

Long Term...Breezy NW winds continue with VFR Saturday morning and early afternoon with gusts 20-30 kts. These do taper off through the afternoon, with light winds overnight. Clouds thicken and lower into Sunday morning with MVFR ceilings expanding and some IFR as well. SN and RA will move in with these clouds, with greatest rates in the afternoon. Precip should trend RA along the coast, with SN causing more vis issues inland from a line AUG, LEW, IZG, and CON for the afternoon. Conditions look to improve Sunday night as the system departs north.

MARINE

Short Term...Solid SCA conditions continue over the waters through tonight before the gradient tightens Friday, resulting in westerly gales over the outer waters and SCA conditions. Winds and seas should begin to come down overnight Friday and toward daybreak Saturday.

Long Term...Winds remain breezy Saturday, falling below 25 kts for Sat evening through Sunday morning. High pressure quickly passes Sat night, with another system approaching Sunday. This will bring the potential for Gales Sunday night. High pressure passes the waters on Monday.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...Small Craft Advisory until 10 AM EST Friday for ANZ150-152-154. Gale Warning from 10 AM Friday to 7 AM EST Saturday for ANZ150- 152-154. Small Craft Advisory from 10 AM Friday to 7 AM EST Saturday for ANZ151. Small Craft Advisory until 7 AM EST Saturday for ANZ153.