textproduct: Gray - Portland

WHAT HAS CHANGED

As of 7 PM have updated PoPs and Wx for the next few hours based on latest radar imagery showing an area of moderate to heavy snow showers moving southeastward out of Oxford County ME. These should make it to the coast. A broken line of snow showers also exists across portions of central and northern NH and we will watch the progress of these as well. Will continue to issue occasional SPSs for this activity mainly for low vsbys and locally slick travel.

KEY MESSAGES

1) Winds become gusty tonight out of the west behind a cold front. Gusts up to 40 mph will be possible and a snow squall or two is not out of the question.

2) Above normal temperatures expected through midweek with a weak system bringing light rain and snow showers Tuesday night into Wednesday.

3) Temperatures trend colder the second half of the week with potential for more widespread wintry precipitation Thursday into Friday.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION... As one low continues moving out to sea, another will move off to our north which will keep the weather unsettled across the forecast area. Dry slotting in between the two lows will give us a little bit of break in precipitation, but should see some more snow showers later today.

The northern low will drag a surface boundary across the forecast area tonight, shifting winds to out of the west as they become gusty on the backside. Forecast soundings continue to show the potential for widespread 30 to 40 mph gusts through Monday morning. Snow shower activity will also continue behind the front in upslope flow. RAP snow squall parameters generally max out over central and southern New Hampshire overnight, so a couple of snow squalls are not out of the question. While snow showers will mainly be in the mountains, forecast Froude numbers greater than 1 overnight suggest the potential for some showers making their way out of the mountains, possibly into the better environment for squalls. That being said, it appears the best environment for snow squalls will mainly be south of our area. Winds will gradually diminish through the day on Monday, but plenty of upslope snow showers continue in the mountains.

Regarding temperatures, tonight's lows will range from the upper single digits north, to the upper teens and lower 20s south. Behind the front, Monday's highs are forecast to range from the lower 20s north, to the low/mid 30s south. Monday night lows will mainly dip into the upper teens to mid 20s.

KEY MESSAGE 2 DESCRIPTION... Above normal temperatures expected through midweek with a weak system bringing light rain and snow showers Tuesday night into Wednesday.

South to southwest flow and WAA increases Tuesday and Wednesday as low pressure tracks across Quebec and sends a cold front toward New England. Highs are expected to reach the mid 30s to low 40s Tuesday with low to mid 40s possible south of the mountains on Wednesday.

QPF is expected to be light with the low and front...generally a tenth of an inch or less with the higher amounts across the north. This may produce an inch or two of snow Tuesday night into Wednesday morning across the north and mostly rain to the south, although there still could be flakes mixing in at times, especially toward the foothills.

KEY MESSAGE 3 DESCRIPTION... Global models and ensembles are in pretty good agreement for the second half of the workweek in depicting a 500mb trough digging into the Mid-Atlantic and closing off before lifting to the northeast and developing a coastal low. This will bring the next opportunity for widespread precipitation to New England starting as a early as Wednesday night and then into Thursday and Friday. Initially, ptype may be more of a rain and snow mix Wednesday night, but temperature profiles are expected to cool as the low begins to close off and high pressure to the north help lock in the north/northeast flow to bring in the colder air. So eventually ptype is expected to become mostly snow, but uncertainty in the track also make amounts very uncertain at this point.

High pressure brings dry conditions for Saturday, and there is already a decent signal in the ensembles this far out of another chance at widespread precip on Sunday.

AVIATION /00Z MONDAY THROUGH FRIDAY/

Precipitation has ended across most of the area but IFR to MVFR ceilings will continue to linger through at least the early afternoon hours. Some light snow showers will also be possible at HIE and AUG this afternoon. Southern New Hampshire terminals will likely see improvement to VFR early in the afternoon with Maine sites seeing VFR improvement later in the afternoon or in the evening. HIE will likely see MVFR conditions remain in place through at least Monday morning with restrictions potentially returning Monday night.

Outlook:

Tuesday: VFR prevails at most terminals. MVFR possible at HIE.

Tuesday night: IFR possible in snow showers at LEB and HIE. MVFR possible in rain showers elsewhere.

Wednesday: LEB and HIE gradually improve to MVFR as snow tapers off. VFR to possibly MVFR prevails at all other terminals.

Wednesday night IFR possible in snow showers at LEB and HIE. MVFR restrictions more likely at other terminals in light rain early but could lower to IFR if rain transitions to snow.

Thursday and Friday: More widespread precipitation (mostly snow) and IFR flight restrictions possible.

MARINE

Low pressure over the Gulf of Maine will continue moving out to sea today. Westerly winds increase late today and strengthen to gales across the outer waters as another low deepens across the Canadian Maritimes tonight into Monday. Gales should relax through the afternoon on Monday but SCA conditions will remain possible through Monday night. SCA conditions remain likely in the bays as well today through at least Monday.

Tuesday-Sunday...Conditions may briefly fall below SCA levels early Tuesday, but S-SW winds likely increase back to SCA levels later in the day through Wednesday as low pressure passes to the north and a frontal boundary potentially stalls somewhere in the vicinity. Low pressure lifting to the north or northeast along this boundary will likely bring additional periods of SCA conditions and possibly gales through late week. High pressure brings brief improvement Saturday before another system potentially approaches Sunday.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...Gale Warning until 1 PM EST Monday for ANZ150-152-154. Gale Warning from 1 AM to 9 AM EST Monday for ANZ151-153.