textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes to the forecast.

KEY MESSAGES

- A few leftover showers possible this evening, otherwise drying out tonight followed by sunshine and seasonably mild conditions Friday.

- Cooler this weekend. Risk for showers as a low pressure passes by offshore.

- Becoming warmer for most of next week. Although, unsettled conditions return toward the end of next week.

DISCUSSION

KEY MESSAGE 1...A few leftover showers possible this evening, otherwise drying out tonight followed by sunshine and seasonably mild conditions Friday.

Bulk of shower activity has lifted to the north and east. Still some leftover drizzle and patchy fog which will improve by late afternoon. We can't rule out a spot shower this evening as mid level shortwave moves through. Otherwise, drying out overnight as weak front passes followed by NW flow and decreasing PWATs. This will lead to a mostly sunny day on Friday with diurnal CU developing as upper low resides to the north with relatively cold temps aloft. Seasonable temps expected with highs low-mid 60s, except cooler higher terrain.

Dry weather continues into Fri night but another shortwave approaching from the west may bring a few showers mostly after midnight, especially in the interior.

KEY MESSAGE 2...Cooler this weekend. Risk for showers as a low pressure passes by offshore.

The big question for this weekend revolves around how closely a low pressure will get to southern New England. Projected mid level flow has a trough axis west of the Appalachians, with the consensus storm track over the Mid Atlantic into the North Atlantic. A subtle shift in the orientation of this flow could force a storm track closer to our region, with a great risk for showers Saturday Night into Sunday.

Expecting a low track about 125 miles SE of the 40N/70W benchmark at the closest approach of a low pressure Saturday night at present. Latest consensus model output slightly increased rainfall chances across the Cape and islands, as well as portions of the coastal plains of MA and RI. Not looking at much rainfall when all is done by Sunday afternoon. Expecting amounts 0.10 inch or less north and west of I-495, with perhaps 0.50-0.75 inch across the Cape and islands. Will be monitoring the actual approach of this low pressure over the coming days.

KEY MESSAGE 3...Becoming warmer for most of next week. Although, unsettled conditions return toward the end of next week.

High pressure well to our south early next week should boost high temperatures into the 60s Monday and the 70s for Tuesday. Thinking it will remain mainly dry Monday, but then a cold front should pass by sometime Tuesday with a risk for showers. The greatest risk for showers looks to be sometime Wednesday night into Thursday as a low pressure moves through the Great Lakes and pushes a couple of fronts across our region.

AVIATION /18Z THURSDAY THROUGH TUESDAY/

Forecaster Confidence Levels...

Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent.

18z TAF Update...Moderate confidence.

MVFR-IFR conditions persist into the evening, then gradual improvement to VFR from W to E during the night, although patchy fog may develop overnight in spots. VFR continues Fri into Fri night but scattered showers may develop late Fri night in the interior. Winds becoming NW 5-10 kt into this evening increasing to 10-15 kt Fri then becoming light to calm Fri night.

KBOS Terminal...Moderate confidence in TAF. Main uncertainty is the when conditions fully improve to VFR

KBDL Terminal...Moderate confidence in TAF.

Outlook /Saturday through Tuesday/...

Saturday: VFR. Chance SHRA.

Saturday Night: Mainly VFR, with local MVFR possible. Chance SHRA.

Sunday: VFR. Breezy. Chance SHRA.

Sunday Night: VFR.

Monday: VFR. Breezy.

Monday Night: VFR. Breezy. Slight chance SHRA.

Tuesday: VFR. Windy with local gusts up to 30 kt. Slight chance SHRA.

MARINE

Forecaster Confidence Levels...

Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent.

Generally light winds, becoming NW, into Fri then becoming SW late Fri into Fri night. Seas 4-6 ft over outer waters will subside late tonight into Fri. SCA for seas will continue until this time.

Outlook /Saturday through Tuesday/...

Saturday: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers.

Saturday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers.

Sunday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers.

Sunday Night: Winds less than 25 kt. Areas of seas approaching 5 ft.

Monday: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Seas up to 5 ft.

Monday Night: Moderate risk for Small Craft Advisory winds with local gusts up to 30 kt. Seas up to 5 ft.

Tuesday: Strong winds with gusts up to 30 kt. Areas of rough seas.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 6 PM EDT Friday for ANZ250. Small Craft Advisory until 2 AM EDT Friday for ANZ251. Small Craft Advisory until 2 AM EDT Saturday for ANZ254>256.