textproduct: Gray - Portland

WHAT HAS CHANGED

Minor update to near term T/Tds to align with observed trends and to update the Aviation section for the 12z TAFs.

KEY MESSAGES

1. Dry weather continues through the Tuesday with near seasonable temperatures.

2. Wet weather makes a return for the second half of the week.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

No high impact weather is expected through Tuesday as high pressure ridging continues to hold firm across New England. With the high pressure system nearby or just to the east we can expect onshore flow much of the time which will keep temperatures from getting too warm, especially at the coast. Dry weather continues as well.

KEY MESSAGE 2 DESCRIPTION...

Wednesday kicks off a pattern change to rainy conditions, but precipitation chances peak Thursday and Friday, where a soaking rain looks increasingly likely. Wednesday shows scattered (20-40%) rain chances as some remnant energy with the offshore coastal low may phase with the incoming shortwave from the Great Lakes. By Thursday, precipitation chances are widespread (80-100%) as the main trough axis moves in. Some newer guidance is suggesting a dual low pressure structure, with a second low forming near the New England coast as the first low cuts north into Quebec. This may lead to locally enhanced precipitation totals in our vicinity. By Friday, model spread becomes evident, as some guidance members suggest a more progressive system with improving conditions, but others show the second low cutting off over New England, leading to continued rainy conditions into the weekend (although it is unlikely to be raining the entire time).

How much precipitation is on the way? NBM has a widespread 1-2 inches across the entire forecast area, specifically for the ensemble mean from Wednesday-Friday, and some eye-popping values for the 90th percentile (2-4 inches). Keep in mind this is representing a three day rainfall. Therefore, right now we are not concerned about excessive rainfall, but regardless there is the potential for a soaking rainfall which could help make a much needed dent in the current drought conditions. Finally, with cooling temperatures aloft, there is the chance for some mountain snow.

AVIATION /12Z SUNDAY THROUGH THURSDAY/

Through tonight...VFR prevails through today with light east to southeast winds. Winds diminish tonight with VFR expected.

Outlook:

Monday/Monday Night: VFR expected. E winds at 5-10 kts. Coastal terminals may see winds up to 15 kts with an afternoon sea breeze.

Tuesday/Tuesday Night: VFR expected. E-SE winds at 10-20 kts.

Wednesday/Wednesday Night: Lowering ceilings with restrictions likely with developing RA. Winds may exceed 15 kts.

Thursday/Thursday Night: Restrictions likely to continue along with periods of RA. Winds up to 25 kts at coastal terminals.

MARINE

Sub-sca conditions are expected through Tuesday as high pressure builds over the waters.

SCA conditions likely Tuesday night through at least Thursday due to building seas outside of the bays as low pressure crosses over the Gulf of ME. Gale conditions possible for the outer waters Thursday-Friday with gusts up to 40 kts.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...None.