textproduct: Gray - Portland

WHAT HAS CHANGED

Temperatures are on their way down with thin high cloud and near calm wind. Many locations have fallen 6 to 10 degrees over the past hour, particularly inland. Have adjusted this trend over the next few hour before clouds thicken.

KEY MESSAGES

1. Low pressure crosses on Friday, bringing beneficial rainfall to the area.

2. A seasonably cold airmass pushes in behind the system to start the weekend, with wintry conditions across the higher terrain.

3. Mild and dry conditions look to persist from Sunday through much of next week as high pressure dominates over the Northeast.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

High pressure passes through this evening, and quickly moves off to the east through the overnight hours. Meanwhile, low pressure tracks eastward through the Great Lakes overnight tonight, with rain pushing into western New Hampshire by sunrise tomorrow.

Periods of rain and showers move through during the morning, and become more showery by the afternoon across much of New Hampshire and western Maine. Low pressure tracks near the Canadian border through the day, with a cold front crossing through late in the day and through the evening hours. Some additional pop up showers or even a few thunderstorms will be possible across southern New Hampshire where a few peaks of sun help temps push into the mid 60s during the day. Overall around a half inch of rainfall is expected, with a little less across southern areas, and a little more to the north.

KEY MESSAGE 2 DESCRIPTION...

The low pressure system deepens across the Canadian Maritimes on Saturday, while high pressure is building westward into New England. This sets up a gusty northwesterly wind, and transports a Canadian airmass that's cold for mid October. Wind gusts of 25-35 mph are expected through the daytime, while highs range from the 30s across the north, to only near 50 along the coast.

Across the higher terrain, wintertime conditions are expected from Friday night through Sunday morning. Accumulating snowfall across the upslope terrain, temperatures in the teens, and wind chills well below zero are all expected. Wind gusts over 100 mph are expected on Mount Washington on Saturday. Any hikers or those above 2500ft should plan for wintertime conditions this weekend.

Scattered snow showers across the mountains on Saturday morning gradually decrease in coverage through the day, but a few flurries are likely to drift downwind of the mountains through the day while gradually drying up.

Saturday night will then by far be the coldest night of the season across the area. Widespread lows in the 20s and breezy conditions are in store for Saturday night. Lows below freezing are expected to the coastline across the region as well.

KEY MESSAGE 3 DESCRIPTION...

High pressure crests over the region on Sunday and looks to stay nosed in through at least the daylight hours of next Thursday. This will bring an extended period of mild daytime temperatures, and likely some pretty chilly nights due to radiational cooling, as well as dry weather.

Sunday will be the transition day with high temperatures in the low to mid-50s with mostly clear skies, but after a raw Saturday this will probably feel comfortable. Afterwards, most days should feature abundant sunshine with high temperatures in the upper 50s and 60s. Periods of clouds are possible with subtle troughing aloft, but the midlevel airmass looks very dry which will preclude any threat for precipitation. Low temperatures look to be generally around normal being in the upper 20s to mid-30s north to south, but of course any night where strong radiational cooling takes place, can end up quite cold. Looking at long range ensembles 850-700 mb temperatures stay right around the 0 C mark through this stretch so certainly some cold nights could come to fruition, but nothing crazy.

AVIATION /00Z FRIDAY THROUGH TUESDAY/

Through 00z Saturday...VFR continues through midnight local. Clouds will begin thickening and lowering amid onshore flow, and most interior locations will see MVFR cigs becoming dominant shortly after daybreak. Expect a hard crash to IFR cigs for southern NH through the morning, with southern ME following into the early afternoon. HIE may be the only TAF that stays VFR/MVFR through Fri, other than a period of RA BR. There is a weak signal for a period of BR/FG following an initial round of rain in the morning and early afternoon across the forecast area, before the cold front brings another round of showers later in the afternoon with a wind shift. Cigs outside of the mountains trend VFR into the evening, but winds will increase from the NW.

Outlook:

Saturday...MVFR/IFR cigs could remain for HIE through the morning with -SHRASN, otherwise VFR expected. The most notable feature for the day will be NW gusts 25 to 30 kts, slackening in the evening.

Sunday-Tuesday...High pressure brings an extended period of VFR conditions with no sig wx. Wind will tend to follow typical diurnal patterns.

MARINE

Southerly winds freshen ahead of an approaching cold front tonight, with SCA conditions across the waters by mid morning on Friday. The cold front crosses through tomorrow night, with SCA conditions continuing in northwesterly winds late Friday night through Saturday evening. Winds gradually ease Saturday night.

Sub-SCA conditions are expected Sunday through much of next week as high pressure settles over the waters.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...Small Craft Advisory from 8 AM Friday to midnight EDT Saturday night for ANZ150>154.