textproduct: Gray - Portland

SYNOPSIS

Low pressure passing southeast of Cape Cod will continue to pull away from the area tonight with snow near the coast ending this evening. Another shot of cold air builds into the region Monday. A weak disturbance may bring a few snow showers to the mountains on Wednesday. Temperatures will warm above normal the second half of the week as an area of low pressure tracks northwest of New England.

NEAR TERM /THROUGH TONIGHT/

Snow has been falling this morning, with most places reporting near 1-2 inches of snow so far. The snow is coming from a low currently offshore from the Mid-Atlantic. This low will move eastward through the day, with light snow likely to continue. At this point, things are starting to wrap up but up to another inch or so could be possible across southern NH and the coastal plain as a weak norlun trough enhances instability behind the low.

Tonight, northerly flow will kick back up again as a pressure gradient tightens over the region. This will allow for cold air advection through the night, with low temperatures expected to be chilly. However, the persistent light northerly wind at night will prevent radiational cooling and should keep the boundary layer mixed through the night. Both of these factors will lead to a blustery and cold night tonight, but lows will stay above 0F for the most part. Looking at lower single-digits across the north, with lower teens along the coast.

SHORT TERM /MONDAY THROUGH MONDAY NIGHT/

Weak high pressure moves into the area to start the day on Monday. Tranquil but cloudy weather is expected through the day. Northwesterly winds and a cold airmass overhead will likely make Monday a cold and blustery one. High temperatures look to be in the teens and lower 20s for most.

Troughing continues Monday night, with lows remaining in the single digits and teens. Radiational cooling is possible with mostly calm winds and clearing skies in the forecast Monday night.

LONG TERM /TUESDAY THROUGH SUNDAY/

Overview:

An active pattern is likely through the long term period as a series of low pressure systems track across southeast Canada. A warming trend is expected to start Tuesday with temperatures climbing above normal Thursday into Friday. The most robust system will cross Thursday night into Friday with a period of rain to the Canadian Border likely before precipitation changes to snow showers Friday afternoon. Temperatures turn colder over the weekend with another low pressure system bringing chances for light snow.

Key Messages:

*A rain on snow event is looking likely Thursday night into Friday morning. At this time the system looks progressive enough to limit rainfall amounts and the duration of snow melt.

Forecast Details:

High pressure centered south of New England Tuesday will provide mostly fair weather with moderating temperatures. Highs will range from the 20s north to 30s across the south. Low pressure tracks across James Bay into Quebec Tuesday night through Wednesday. Warm air advection ahead of the system will bring temperatures into the mid 30s to low 40s. The trailing cold front will sag into northern zones Wednesday afternoon bringing chances for snow showers in the mountains.

Deep southwest flow will develop Thursday ahead of an area of low pressure moving into the Great Lakes region. This will allow temperatures to climb above freezing across much the area by Thursday afternoon with southern areas getting into the low 40s. Warm air advection may result in some light snow/wintry mix in the mountains Thursday afternoon before mainly rain overspreads the area Thursday night. Low pressure will progress quickly through Quebec Friday morning with rain changing to a brief period of snow in the mountains. Ensemble means are generally 0.5 to 0.75 inches for rainfall with this system and the window for snow melt will be around 12 hours. This should keep hydro issues at a minimum, while trends will be monitored for any signal of higher rainfall amounts. The cold front will cross through the area by Friday evening with temperatures dropping into the single digits north to teens south Friday night.

High pressure briefly builds in Saturday before the next low pressure system approaches from the west. This system will track more west to east across northern New England bringing potential for more in the way of snow Saturday night.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

Short Term...Restrictions are likely through this afternoon as snow moves through the area. Restrictions lift overnight as low pressure moves away. Some lower CIGs are possible tomorrow morning but VFR is generally expected tomorrow and will continue through Tuesday morning.

Long Term...Mainly VFR Tuesday into Thursday morning. A cold front crosses Thursday night through Friday bringing mainly rain and likely periods of restrictions. Southerly winds aloft will also bring the threat of LLWS Thursday night.

MARINE

Short Term...Northwest winds will pick up this afternoon as a pressure gradient sets up over the waters. These winds are likely to strengthen to Gale force winds by this evening and will continue through tomorrow afternoon. Northwest winds gradually slacken through the remainder of the day Monday, with westerly winds of 12-21kts expected by Tuesday morning. Seas are expected to be 4-7ft from now through Tuesday morning.

Long Term...Winds and seas will be low SCA thresholds Tuesday. SW winds increase Tuesday night through Wednesday with gusts to Gale force possible over the outer waters. Winds turn briefly offshore Wednesday night before another surge of southerly flow Thursday ahead of a cold front. Southerly winds will approach Gale force Thursday night.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...Gale Warning from 7 PM this evening to 1 PM EST Monday for ANZ150-152-154. Small Craft Advisory until 3 PM EST Monday for ANZ151-153.