textproduct: Gray - Portland

WHAT HAS CHANGED

No significant changes with this forecast update.

KEY MESSAGES

1. Low pressure tracking across northern Quebec will drag a cold front across the area tonight bringing widespread showers. Rainfall amounts will be light.

2. Gusty winds with lower humidity Thursday. Mostly dry weather then looks to continue through most of the weekend. Next low impact precipitation chances return Sunday into the next work week.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

The backdoor front that moved through yesterday will lift northward as a warm front today as a strong area of low pressure over Hudson Bay moves into Quebec. The warm front will provide a focus for clouds today with mostly cloudy skies across much of the area by this morning. As deeper moisture arrives there will be chances for isolated showers while the bulk of the shower activity arrives with the approaching cold front this evening through tonight.

Showers and thunderstorms will form along and ahead of the cold front across the eastern Great Lakes into New York late this afternoon. Instability will be waning as thunderstorms move across Vermont and approach the CT Valley after sunset. A few rumbles of thunder remain possible tonight while most areas will see 4 to 6 hour window of showers overnight. High PWATs may allow periods of moderate rainfall while overall rainfall amounts will be light with many areas likely only picking up a tenth of an inch. Showers will end NW to SE going into Thursday morning.

KEY MESSAGE 2 DESCRIPTION...

We could see a few lingering showers Thursday morning but this activity will be brief as high pressure settles in behind a pair of cold fronts.

Westerly winds will already be breezy Thursday morning but will turn fairly gusty in the afternoon behind the secondary cold front after it sweeps through. Strong cold air advection, steep low-level lapse rates, and decent 3-hour pressure rises (2 to 4 mb) will provide favorable conditions for gusty winds to mix their way down to the surface. The NAM still seems to be a bit of a stronger outlier with regards to winds at the top of the mixed layer, but widespread gusts in the 25 to 35 mph seem reasonable with some isolated gusts up to 40 mph.

High temperatures on Thursday will be warmer for those ahead of the secondary front with some low to mid 80s possible across the southern half of New Hampshire and interior/coastal Maine. Thursday night will see some cooler lows behind the front, but lingering breezy winds and cloud cover will keep temperatures from bottoming out too much. Forecast lows range from the mid to upper 40s north, to the mid to upper 50s south and along the coast.

Not much has changed with regards to Friday's forecast and beyond: cooler, dry, and breezy with northwest winds gusting up to 25 mph through the first part of the day. Highs will mainly range from the low to mid 60s north, to the low to mid 70s south. Winds then relax under a clear sky Friday night which will lead to favorable radiational cooling conditions. Expect widespread lows in the low to mid 40s with some mid to upper 30s possible in the northern valleys.

The next trough and front will approach on Sunday or Monday, leading to our next chances of precipitation which appears to be low impact at this time. Expect highs mainly in the 70s through the weekend and into the next work week with a couple of lower 80s across far southern New Hampshire.

AVIATION /01Z WEDNESDAY THROUGH SUNDAY/

Through tonight...Mainly VFR conditions expected through today, except for some local IFR or lower in fog at LEB and HIE early this morning. Clouds thicken and lower through today with MVFR cigs possible by this evening. Cigs continue to lower tonight with SHRA likely bringing widespread MVFR to IFR for several hours around 06Z. Conditions improve NW to SE early Thursday morning as winds turn westerly and SHRA exit offshore.

Outlook:

Thursday: Mainly VFR with west winds gusting 25-30 kt, possibly as high as 35 kt.

Thursday night-Saturday: Mainly VFR. Valley fog possible at HIE and LEB by Friday night.

Sunday-Sunday night: Generally VFR, with MVFR possible as showers move into the area.

MARINE

Winds and seas stay below SCA thresholds into this afternoon. Southerly winds increase late afternoon and turn southwest tonight with SCA conditions expected for all waters overnight. SW winds to 25 kts and seas around 5 feet will keep SCA conditions going outside the bays Thursday with winds subsiding Thursday afternoon and night as they shift W to NW. High pressure builds in Friday through Saturday for quiet conditions on the waters. The next system approaches Sunday bringing southerly winds approaching 25 kts.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...Small Craft Advisory from 8 PM Wednesday to 8 PM EDT Thursday for ANZ150-152-154. Small Craft Advisory from 8 PM Wednesday to 8 AM EDT Thursday for ANZ151-153.