textproduct: Gray - Portland

WHAT HAS CHANGED

Little change to the going forecast this evening other than to increase clouds through about midnight in the interior.

KEY MESSAGES

1. Warmer temperatures in store for Saturday.

2. An area of snow will move across the forecast area Sunday resulting in a quick but light accumulation of snow.

3. Next week harbors a couple chances for precipitation, mainly in the Tuesday/Tuesday night and late week timeframe, as well as a fairly confident signal for a late week warm up. This pattern could result in mixed wintry precipitation for a portion of the area, as well as snowmelt/and some river ice rot during the daytime.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...A cold front will approach the region Sat and will affect sensible weather in two ways. One will be warm advection and compressional warming ahead of the front will allow temps to climb into the 40s. There may even be a run at 50 degrees for a few locations. Across the interior the southwest flow may also fail to really scour out the low level cold, especially with deep snow cover, and afternoon readings could end up closer to 40. The second factor will be showers along the front. Given the mild temps these may be rain or snow depending on location and time of arrival. And precip may be briefly heavy as it moves thru quickly during the afternoon and evening. This will mainly affect the mtns and maybe clip the lower Kennebec River Valley.

KEY MESSAGE 2 DESCRIPTION... A trough passing through New England will bring a period of light snow to the forecast area Sunday. Forecast accumulations come out to just around an inch, but will push through the CWA through the day. Morning travel could be slick across much of NH, with the afternoon focus on ME.

Overall lift is limited despite a deepening DGZ. Thus would expect increased snow rates to be brief within the event. NBM v5 probabilities of exceeding 2" are also below 20% for the area through Sunday evening.

The passing trough will welcome back much cooler temperatures overnight, with lows plummeting back into the single digits above and below zero.

KEY MESSAGE 3 DESCRIPTION... Three topics for next week featuring two main precip windows and then a warming temperature trend. The two precip makers still have a wide range of outcomes, with even the warming trend including an asterisk with it.

Focusing first on the early to mid week system, it follows on the heels of exiting high pressure across the eastern CONUS. Highs don't get as much glory as their counterparts, but the increasing chance of a 1040mb MSLP high through the Northeast represents a strong high for this time of year. It will be responsible for a cool down Sunday night through Monday night (highs in the teens and 20s, lows in the single digits above and below zero), and also swift return, warming, flow into the middle of the week. QPF presentation of low pressure flatly exiting the Great Lakes and Ohio Valley is represented across guidance, but some hints of phasing and different transit speed leaves a lot on the table for potential totals and temperature profiles. Given the chance for above freezing temperature layers in this system, mixed precip may be possible for a portion of the area. For now this could materialize across the southern third of the forecast area.

Into late week, another system looks possible, along with a likely warmup. This will again likely feature strong high pressure, instead positioned to the north and west. Will need to watch how much dry air could be forced into northern New England for late week that could temper QPF expectations. This high will also play a role in how far north the second system pushes, thus exactly how warm it gets late week will also depend on this weather system. For now, highs in the 40s Wed-Thurs and maybe Friday will be possible. As with the early week system, a chance for mixed precip also exists with the next round. As ensembles struggle represent CAD, would need rely on broad pattern recognition should overnight temps in the teens and 20s lock in across the interior.

AVIATION /00Z SATURDAY THROUGH WEDNESDAY/

Through 18z Saturday...VFR conditions prevail thru Sat afternoon. Some high clouds tonight will not impact flight conditions. An approaching cold front may bring scattered rain and snow showers to the mtns Sat afternoon. Local MVFR or lower conditions are possible, mainly at HIE.

Outlook...

Saturday Night: Continued VFR overnight with thickening and lowering cigs.

Sunday: MVFR cigs with MVFR to IFR vis in SN.

Sunday Night thru Monday Night: Improving to VFR in the evening and overnight as high pressure settles overhead.

Tuesday and Tuesday Night: Skies thicken and lower with the chance of SN reducing visibility. Uncertainty on timing and exact impacts.

MARINE

Southwest winds will increase tonight ahead of an approaching cold front. Warm advection over cold ocean waters will struggle to mix down the strongest wind gusts, but a period of marginal SCA gusts is expected Sat. SCA remain in effect for all waters. Winds and seas will begin to diminish Sat night.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...Small Craft Advisory until 10 PM EST Saturday for ANZ150-152- 154. Small Craft Advisory from 11 PM this evening to 4 PM EST Saturday for ANZ151-153.