textproduct: Gray - Portland

WHAT HAS CHANGED

Chances for widespread snow late Tuesday into Wednesday have increased along with snowfall amounts.

KEY MESSAGES

1. Gusty winds continue through today with a cold air mass in place. Wind chills will be -15F to -25F across much of New Hampshire and interior western Maine where Cold Weather Advisories are in place through mid morning.

2. Widespread snow is likely late Tuesday into Wednesday. Accumulating snow will bring potential impacts to the Tuesday evening commute and the Wednesday morning commute.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION... Another cold morning is store for much of the area. The wind in some areas have gone calm allowing temperatures to radiate quickly with KHIE at -21F as of this writing. Areas that remain breezy will see wind chills below zero with areas in the Advisory seeing wind chills of -15F to -25F below.

Northwest winds will remain breezy through today with gusts up to 25 mph. Temperatures will be warmer than yesterday, but still seasonably cold with highs in the teens and 20s. Winds relax tonight allowing for favorable radiational cooling. This will bring another night with temperatures well below zero across the north and near zero across the south.

KEY MESSAGE 2 DESCRIPTION... Model trends are showing a signal for higher snowfall totals for Tuesday afternoon/night's system. The snow will arrive with a mid- level warm front passing southeastward. The increase in snow amounts makes sense given a few factors. First, the surface low is in an upper- level divergence zone, which will allow for the low to strengthen with its passage. Next, the potential development of a TROWAL with this system may bring the possibility of mesoscale snowbanding, especially along the frontal boundary. Third, southerly flow at the onset of the system's arrival may also allow for some upslope enhancement in the mountains, especially the southern half.

Despite the increase in expected snowfall, mostly only minor accumulations are likely. At the moment, we have about 3-5 inches of snow, and perhaps reaching over 6 inches locally. Still, impacts should remain limited to just some minor travel impacts during the Tuesday evening and Wednesday AM commute. Snow showers may continue through the remainder of the day Wednesday as the surface trough lingers over the area.

AVIATION /06Z MONDAY THROUGH FRIDAY/

Through 00z Tuesday: VFR with some MVFR ceilings towards HIE. There is some uncertainty on how much coverage these clouds produce. There will be a lower jet of 40 kt winds moving through tonight, creating some LLWS for most interior terminals. LLWS should slacken Mon morning as surface winds again pick up due to mixing.

Outlook...

Monday Night: VFR with no sig wx.

Tuesday: IFR or lower conditions developing later in the day.

Tuesday Night: IFR or lower conditions in light snow.

Wednesday: Widespread IFR ending, but lingering local IFR or lower possible in snow showers.

Wednesday Night: VFR conditions expected.

Thursday: VFR conditions expected.

Thursday Night: VFR conditions expected.

Friday: VFR conditions expected.

MARINE

Northwest winds diminish some through morning while gusts will continue to be in the 25 to 30 kts range into tonight. Moderate freezing spray is likely into mid morning. Winds and seas drop below SCA thresholds Monday night.

Winds and seas will continue to diminish Tue and remain below SCA thresholds. Towards the weekend conditions well outside the bays may approach marginal SCA criteria, but largely expecting the majority of the marine zones to stay below headline.

GYX WATCHES/WARNINGS/ADVISORIES

ME...Cold Weather Advisory until 10 AM EST this morning for MEZ007- 012-018-019-033. NH...Cold Weather Advisory until 10 AM EST this morning for NHZ001>011-015. MARINE...Small Craft Advisory until 1 AM EST Tuesday for ANZ150-152-154. Freezing Spray Advisory until 10 AM EST this morning for ANZ150>154. Small Craft Advisory until 4 PM EST this afternoon for ANZ151- 153.