textproduct: Gray - Portland

WHAT HAS CHANGED

Allowed the small craft advisory to expire. Also, blended in the latest surface observations to better align the forecast. Otherwise, no major changes were needed at this time.

KEY MESSAGES

1. Cold weather continues through Monday. A weather system approaches from the west on Tuesday likely spreading snow across central and southern zones for the evening commute.

2. Low pressure brings a round of light snow and mixed precip late Tuesday into Tuesday night.

3. Mild air makes northward progress into New England mid to late week, with more chances for precip late week.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION... Fair but cold weather is expected today. Low pressure will approach from the west on Tuesday and will likely spread a wet snow across southern and central zones by the time of the evening commute. This may cause for slippery conditions on colder untreated surfaces.

KEY MESSAGE 2 DESCRIPTION... A wave of low pressure rides eastward into New England late Tuesday and into Tuesday night, spreading snow from south to north during the afternoon and evening hours. After temps warm into the upper 30s to near 40 during the day, they quickly drop back to near freezing once the snow arrives. There likely won't be much accumulation during the daylight hours following the mild day, but the snow will then stick after sunset.

Some warmer air progresses in aloft across southern NH, so some sleet and freezing rain will be possible here and into southwest Maine after the period of snow. Some plain rain is also possible through the Seacoast as temperatures may creep back up just above freezing toward the end of the event.

There does look to be a tapering off in the snowfall toward northern areas, with limited accumulations across the north. In central and southern areas that remain snow, a general 1-3 inches of snow is expected. Some locally higher amounts are possible, with a narrow band of higher ratio snow possible where temps sit at about 30-31 degrees Friday night.

KEY MESSAGE 3 DESCRIPTION... Warmer air then has some success in mixing to the ground on Wednesday, with temps warming into the 40s to near 50 in many areas. The cool air then tries to make a comeback on Thursday with a backdoor cold front. Models still remain split on whether this front pushes back through and brings cooler air, or if mild temps hold on for one more day. History suggests that the cool air will find it's way back in sooner given the time of year and lingering nearby front.

Another wave of low pressure then approaches on Friday. Models have been back and forth on how much moisture will make it from this system, but they have trended colder ahead of any moisture that does make it. This would lead to a snowier solution across northern and eastern areas, with more of a mix toward the south and west. We'll continue to monitor this, as there are models that show very little moisture making it into the region as well.

AVIATION /12Z MONDAY THROUGH FRIDAY/

Through 12Z Tuesday: VFR conditions with light winds this morning increasing to 10-15 kts this afternoon out of the NW. Winds will become light and variable tonight with VFR conditions continuing. No LLWS is anticipated through the period.

Outlook...

Tuesday/Tuesday night: Snow will overspread the region from W-E during the afternoon and evening before gradually ending overnight Tuesday night. Also can't rule out a brief period of -PL/-FZRA or even RA at MHT, CON, PSM, and PWM.

Wednesday - Wednesday night: Improving conditions with any leftover precip coming to an end in the morning. Mainly VFR otherwise.

Thursday - Friday: Several rounds of mixed precip and IFR are possible through this time period.

MARINE

Small craft conditions are expected to develop tonight and last into Tuesday in the southerly flow regime. SCA to near marginal gales are possible in southerly flow Tuesday night. Conditions ease as high pressure crosses the waters on Wednesday. Then, SCA conditions in northeasterly flow are possible as early as Thursday, but more likely Friday, as a backdoor cold front crosses the waters.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...Freezing Spray Advisory until 1 PM EST this afternoon for ANZ150>154.