textproduct: Gray - Portland

WHAT HAS CHANGED

No significant changes with this forecast update.

KEY MESSAGES

1. A cool and dry airmass remains in place through today. There will be potential for elevated fire weather concerns today with min RH around 20-25 percent, although winds will be light.

2. Temperatures moderate mid week with chances for light precipitation Wednesday into Thursday.

3. Warmer temperatures and dry northwest flow will bring potential fire weather concerns Thursday and Friday across southern New Hampshire.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

High pressure crests over the area this morning yielding a cold start to the day with morning lows in the teens north and 20s south. Mostly sunny skies to start will transition to mix a sun and clouds during the afternoon with highs in the 40s north to low 50s across southern New Hampshire. Winds will be light, although model soundings continue to show mixing to around 800 mb that should allow for dew points to drop into the single digits across the interior. This will result in min RH dropping to around 20 to 25 percent early this afternoon across the interior. A sea breeze will develop late morning and press inland through the afternoon helping to increase RH along the coast into the interior. Winds will generally be 10 mph or less across the interior with the sea breeze bringing gusts upwards of 15 mph along the coast.

KEY MESSAGE 2 DESCRIPTION...

A weak frontal system will cross tonight through Wednesday bringing more in the way of clouds and slight chances for snow showers from the foothills northward and slight chances for rain showers south of the foothills. With dry air in place, any measurable precipitation from this system will be hard to come by. Highs on Wednesday will mainly be in the 40s with low 50s across southern NH.

A short wave will drop southeast out of Canada Wednesday night and Thursday. This system will also be lacking moisture, but will again bring slight chances for mountain snow showers and rain showers to the south. Temperatures do moderate aloft leading to highs ranging from the mid 40s north to upper 50s south.

KEY MESSAGE 3 DESCRIPTION...

The risk for fire weather concerns increase at the end of the week. Modestly warmer conditions are forecast with a light northwesterly diurnal breeze. These winds could allow for some downsloping enhancement, and could allow for stronger mixing and a drier column south of the mountains. Saturday could be another dry day too, with temperatures and dewpoints generally running about 5 degrees warmer than on Friday. Dry conditions are favored through the rest of the weekend, though relative humidity could improve and become more moist for Sunday.

AVIATION /09Z TUESDAY THROUGH SATURDAY/

Through 12z Wednesday...VFR today. A sea breeze will bring a southerly wind shift and some gusts to PSM/PWM/RKD early this afternoon, before winds slacken again in the evening. Expect a more widespread thickening and lowering of cloud bases this evening, with MVFR settling over much of NH by 12z Wed. Some uncertainty if a second area of MVFR ceilings develop along and inland from the ME Midcoast early Wed morning, but overall trend will be MVFR towards noontime. SHRASN arrives with these lowered ceilings, with SN causing decreased vis for foothill and mountain locations.

Outlook:

Wednesday- Wednesday night: Low ceilings and low chances for rain showers will bring periods of MVFR. Otherwise, periods of VFR are likely.

Thursday: Chances for rain and mountain snow chances will bring the potential for restrictions. Southern NH TAF sites likely remain VFR.

Friday: VFR conditions expected.

Saturday and Sunday: VFR most likely.

MARINE

Winds and seas generally remain below SCA thresholds through the end of the week and into the weekend. High pressure builds in from the west and settles south of the waters tonight. Offshore winds early this morning turn onshore today. Southerly winds increase tonight and Wednesday with the passing of a weak frontal system that will bring low clouds and chances for showers and possibly some fog. Winds turn offshore Thursday through Friday.

GYX WATCHES/WARNINGS/ADVISORIES

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