textproduct: Gray - Portland

WHAT HAS CHANGED

Snowfall totals across southern NH into southwestern Maine have increased slightly to approach 20 inches.

Gale watch has been upgraded to a gale warning.

KEY MESSAGES

1. Bitterly cold weather continues even as winds finally relax. Cold weather advisories remain in effect for much of the mtns and foothills.

2. Major winter storm begins this afternoon and continues thru Mon. Widespread double digit snowfall is anticipated, and amounts approaching 18 inches are possible for southern NH and parts of southwestern Maine. All snow is expected but significant travel disruptions are likely beginning Sun night thru Mon morning.

3. Below normal temperatures continue Tuesday through the end of the work week. After the winter storm moves out Monday night into Tuesday morning, low chances for snow return by the end of the week outside of some periodic mountain snow showers.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION: As anticipated where winds have gone calm temps have already fallen to or below NBM min temps. At the same time a pesky band of cirrus is drifting north across the forecast area and stalling the temp drop. Either way it remains very cold and cold weather advisories remain in effect. Calm locales in the northern valleys will likely make a run at 20 below, while places that maintain a slight breeze will hit 20 below on wind chill.

KEY MESSAGE 2 DESCRIPTION: Consensus is growing that a major nor'easter will impact the area this afternoon thru Mon with widespread double digit snowfall totals.

Timing is maybe the most high confidence aspect of the storm. Snow is expected to rapidly break out from southwest to northeast between around 1 pm and 4 pm. In addition the heaviest snowfall rates are anticipated between 7 pm and 1 am.

Overall the evolution of the storm is impressive from a modeling perspective. All guidance indicates an intense push of warm air advection induced frontogenesis will translate across much of the Northeast. The combined lift, QPF, and snow ratios suggest 2 to 3 inches per hour is not out of the question as this forcing moves thru. The key is that it is moving at 700 mb. This will likely bring a fairly uniform snowfall to much of the forecast area. Then the 850 mb front lifts towards our southern zones then stalls and drifts eastward thru the duration of the storm. This forcing is likely what will give us our highest snowfall totals as it will have the longest residence time over the same areas. Overall there was little change to the previous snowfall forecast except to include a small area of 18-24 inches where guidance is showing strong agreement.

The worst of the conditions will last at least several hours at any given location. Travel will be dangerous Sun night into Mon morning.

KEY MESSAGE 3 DESCRIPTION: After the aforementioned winter storm exits the region, mostly tranquil but brisk weather is expected. This is due to the presence of an upper-level low over Quebec. The upper-level low will continue to gyrate through the week, allowing for persistent doses of arctic air with no signs of a thaw in sight. High temperatures through most of next week look to be in the teens, with lows often in the single digits or below zero. Despite the cold temperatures, winds should be on the calmer side, with perhaps a light northwest breeze on Tuesday. So while this week will feel brisk, the wind chills should not be nearly as bad as they were this morning (Jan 24). Other than the chillier temperatures, minimal impacts are expected after Tuesday morning.

AVIATION /06Z SUNDAY THROUGH THURSDAY/

VFR conditions are expected to prevail thru midday. Snow will quickly move into the region from southwest to northeast and conditions are expected to drop rapidly from VFR to LIFR, generally between 18 and 21z. The heaviest snowfall, in excess of 1 inch per hour over southern NH and southwestern Maine, is expected between 00z and 09z Mon. While VIS is likely to be one quarter mile or less at times anyway, very near the coast northeast surface gusts may approach 20 to 25 kt thru Mon morning.

Outlook:

Monday: Areas of IFR. Snow continues but intensity will be diminishing. Winds shifting to north northwest and gusts around 20 kt.

Monday Night: Trending VFR. Winds shift NW 15 to 20 kts. HIE may keep MVFR ceilings with light SN.

Tuesday, Wednesday, and Thursday: Mostly VFR with no sig wx. W winds 15 to 20 kts. MVFR ceilings may remain NW of the Whites.

MARINE

Winds continue to diminish but will remain breezy across the waters thru morning. With temps remaining very cold freezing spray will still be a hazard and the freezing spray advisory remains in effect thru mid morning. Then attention will quickly turn to developing nor'easter. Northeast winds will steadily increase in the afternoon with gale force wind gusts possible on the outer waters around midnight. The gale watch has been upgraded to a gale warning. Overnight Sun into Mon will be the heaviest snowfall, and visibility of one quarter mile or less is possible over the coastal waters. Those winds will gradually back to north northwesterly thru midday Mon as they slowly diminish.

Gale force westerly winds with 8-12ft seas expected Monday night and into Tuesday morning. Winds and seas lower to SCA levels by the end of the day Tuesday, with 3-6ft seas expected Tuesday and through the end of the day Wednesday. Beyond Wednesday, expect winds and seas to go back and forth between normal and SCA conditions.

GYX WATCHES/WARNINGS/ADVISORIES

ME...Cold Weather Advisory until 7 AM EST Sunday for MEZ007>009- 012>014-033. Winter Storm Warning from 7 PM Sunday to 1 AM EST Tuesday for MEZ007>009-012>014-019>022-024>028-033. Winter Storm Warning from 1 PM Sunday to 7 PM EST Monday for MEZ018-023. NH...Cold Weather Advisory until 7 AM EST Sunday for NHZ001>004. Winter Storm Warning from 1 PM Sunday to 7 PM EST Monday for NHZ001>015. MARINE...Freezing Spray Advisory until 10 AM EST Sunday for ANZ150>154. Gale Warning from midnight Sunday night to 4 PM EST Monday for ANZ150-152-154. Small Craft Advisory from 1 AM to 7 PM EST Monday for ANZ151- 153.