textproduct: Gray - Portland

WHAT HAS CHANGED

Chances for snow have shifted south through Wednesday night and snowfall amounts have come down.

KEY MESSAGES

1. A stalled frontal boundary will provide a focus for rain and snow to develop near the NH/MA border this afternoon with precipitation becoming all snow this evening before ending around midnight. Overall this system has trended drier with snowfall amounts around a coating to an inch across the southern counties of NH. Some slick travel is still possible for the evening commute.

2. An active pattern is expected over the weekend, with one system likely to move through the area on Friday evening. While conditions look supportive of mostly snow, there remains a wide spread of solutions for snow magnitude and where it falls. More unsettled weather may be possible in the Sunday/Monday timeframe.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION... A cold front crossing the region early this morning will stall across southern New England through tonight. Latest available 00z guidance has trended drier with precipitation that forms along this boundary with many model solutions keeping precipitation confined south of the NH/MA border. The latest NBM has come down significantly in both chances for snow and snow accumulations. Chances for snow are now confined to the southern tier of counties in New Hampshire with PoPs topping out around 50 percent along the NH/MA border. Likewise, snow amounts of a coating to an inch are confined to an area from Keene to Manchester and points southward. The best chances for accumulating snow will occur around the time for the evening commute some slick travel still remains possible. Chances for snow will diminish between 10 PM and Midnight tonight.

KEY MESSAGE 2 DESCRIPTION... An occluding low over the Great Lakes on Thursday may allow for the development of low pressure over the east coast on Friday. The redevelopment should limit warm air advection into the northeast, which will allow for temperatures to stay colder across the region. For most across our area, thermal profiles generally look to be supportive of mostly snow despite above freezing high temperatures on Friday and Saturday. The low could intensify as it leaves New England, with measurable snow possible across New Hampshire and Maine. At this point, models seem to be struggling the most with QPF, as some members have a much broader shield of snow over the area than others. Slick and snow covered roads are possible for the Friday evening and Saturday morning commutes.

We are keeping an eye on a potential system in the Sunday/Monday timeframe as well. A lot of uncertainty exists with this potential system, with all solutions remaining on the table.

AVIATION /04Z WEDNESDAY THROUGH SUNDAY/

Through 00Z Thursday...Ceilings have scattered across southern TAF sites with all sites trending towards VFR between 07Z and 11Z. Clouds thicken and lower across southern NH starting around 18Z. Some light snow will be possible near the NH/MA border from 21Z until 04Z. KMHT will see the best chance to see some MVFR during this time while remaining TAF sites likely stay VFR.

Outlook...

Wednesday Night: MVFR cigs may remain across far southern NH, trending to VFR overnight.

Thursday and Thursday night: VFR w/ no sig wx.

Friday and Friday night: MVFR cigs approach from the west across NH with SN. IFR vis possible in SN.

Saturday: Uncertainty how quickly SN exits east along with ceiling restrictions.

Saturday night and Sunday: Trend should be VFR with high pressure to the north.

MARINE

Seas along the outer waters will run near 5 feet through today followed by a period of northerly winds gusting 20-25 kts tonight. Have hoisted an SCA for the outer waters through 12z Thursday. High pressure building in from the north brings quiet conditions over the waters Thursday.

Low pressure tracks across southern New England Friday into Saturday bringing increased NE flow. This will bring a period of SCA conditions with gusts up to 30 kts. In NE winds, wave heights should respond, building 5 to 6 ft off the NH seacoast and southern ME coast.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...Small Craft Advisory until 7 AM EST Thursday for ANZ150-152- 154.