textproduct: Gray - Portland

WHAT HAS CHANGED

No significant changes since the last forecast package.

KEY MESSAGES

1. Cold air arriving on gusty winds will continue dangerously cold wind chills through mid morning. It will remain cold and windy through the afternoon with wind chills staying near or below zero across the area.

2. There is a chance of light snow Tuesday into Wednesday. The timing may be such that it impacts the AM commute on Wednesday.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION... Cold air advection is underway early this morning as northwest winds have climbed to 20 to 30 mph across the area. These winds will continue through the morning as air temperatures drop to -5F to -10F across the mountains and western New Hampshire. These temperatures combined with the wind will bring wind chills around -25F with the Extreme Cold Warning and Cold Weather Advisories remaining in effect. Temperatures will not drop as low farther east while the remaining Cold Weather Advisory remains in effect for windchills of -15F to -20F. In the higher terrain wind chills will be much colder around -40F.

There will be more in the way of sunshine today while temperatures will remain below normal. Highs will range from the single digits north of the mountains to the teens to low 20s south of the mountains. Winds will remain steady through today as the pressure gradient does not relax much with gusts to 20-30 mph. This will keep wind chills below zero for much of the area. Winds come down some tonight while it will remain cold with wind chills -5F to -15F south to north.

KEY MESSAGE 2 DESCRIPTION... An Alberta Clipper will move through the northeast Tuesday night and into Wednesday morning. The cold air overhead will allow for the snow to be on the lighter and drier side, with snow ratios in the range of 12-16:1. Travel impacts to the Wednesday morning commute are likely but should be minor with most of the snowfall wrapping up by the AM commute. In addition, snowfall amounts will be fairly light with about 1-3 inches expected across NH and Western Maine. Some upslope enhancement may allow for some localized 3-6 inch totals in the White Mountains.

AVIATION /03Z SUNDAY THROUGH THURSDAY/

Through Sunday: Conditions have largely improved to VFR with VFR likely to prevail into Sunday. A cold front has now crossed much of the area with gusty NW winds to around 20 to 30 kts, continuing Sunday. Winds slacken into Sunday evening, but steady winds should continue. Otherwise VFR.

Outlook...

Tonight: VFR expected with WNW winds 10 to 20 kts.

Monday: VFR conditions expected.

Monday Night: VFR conditions expected.

Tuesday: Increasing clouds and lowering CIGs but mostly VFR expected thru evening.

Tuesday Night: Areas of IFR in light snow.

Wednesday: IFR conditions improving but may continue to be local IFR or lower in snow showers.

Wednesday Night: VFR conditions expected.

Thursday: VFR conditions expected.

MARINE

A strong cold front has pushed through the waters with northwest winds gusting to around 35 kts. Winds drop slightly this afternoon but will remain around 30 kts through tonight. The combination of the cold airmass and gusty winds will create an extended period of moderate freezing spray through tonight.

SCA conditions are likely to continue through Tuesday morning, with winds going below SCA levels during the day. Sub-SCA levels continue through the remainder of the week.

GYX WATCHES/WARNINGS/ADVISORIES

ME...Cold Weather Advisory until 10 AM EST Sunday for MEZ007>009- 012-013-018-019-033. NH...Cold Weather Advisory until 10 AM EST Sunday for NHZ001>006- 009-010-012-013. Extreme Cold Warning until 10 AM EST Sunday for NHZ007-008-011- 015. MARINE...Gale Warning until 1 PM EST Sunday for ANZ150>154. Freezing Spray Advisory until 7 AM EST Monday for ANZ150>154.