textproduct: Boston / Norton

WHAT HAS CHANGED

Increasing confidence in a soggy, wet weather pattern for early to middle of next week.

KEY MESSAGES

- Scattered showers and embedded thunderstorms weaken and dissipate by sundown, with clearing skies overnight. Patchy fog possible.

- Slow-moving frontal boundary nearby Southern New England could favor several opportunities for showers and thunderstorms Monday through Wednesday, with street flooding possible.

DISCUSSION

KEY MESSAGE 1...Scattered showers and embedded thunderstorms weaken and dissipate by sundown, with clearing skies overnight. Patchy fog possible.

Upper level low continues to pull away this afternoon into tonight. However scattered instability type showers have developed this afternoon in a weakly-unstable convective setting, with a couple being capable of a few lightning strikes. Expect activity to move gradually off to the south and east, with diminishing coverage and strength as we move toward sunset. Severe weather is not expected, and even lightning will be tough to come by. We do clear out tonight, and with that comes the risk for patchy fog; the more typically favored areas are most susceptible to patchy fog development.

Saturday into Sunday otherwise looks favorable with full sun and seasonable temps, with seabreezes at the coast.

KEY MESSAGE 2...Slow-moving frontal boundary nearby Southern New England could favor several opportunities for showers and thunderstorms Monday through Wednesday, with street flooding possible.

Latest ensembles point to an unsettled and potentially active early to midweek as a slow-moving frontal boundary remains nearby or over Southern New England, with an influx of subtropical moisture on southwesterly flow aloft. Main risk this front will bring to Southern New England is another period of soaking downpours given the slow-moving frontal zone interacting with the highly moisture- rich airmass preceding it. It's still uncertain what the highest rain totals would look like and where they would fall, but with a few spot areas in interior Southern New England having registered quite a bit of rain in the last 48 hours, there would be some risk for localized street flooding. Probabilities for rainfall over 1" in 24 hours has increased into the lower to moderate (20-40%) range. Severe weather potential looks limited.

AVIATION /20Z FRIDAY THROUGH WEDNESDAY/

Forecaster Confidence Levels...

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

18z TAF Update:

Through 00z Saturday: High confidence.

Mainly VFR outside of SCT SHRA/psbl isolated TS (best chance of TS mainly BDL). SHRA/TS should begin to weaken by 00z Sat. Light north winds, seabreezes near the eastern MA coast.

Tonight: High confidence, though moderate on fog coverage.

Lingering SHRA thru 01z but should trend dry thereafter. VFR through midnight, but patchy fog could develop overnight. Best chance at BDL, BED and ORH. SW winds around 5 kt, becoming light/calm overnight.

Saturday: High confidence.

VFR. SW winds around 5-10 kt, with seabreezes developing at BOS around 14-15z.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Saturday Night through Wednesday/...

Sunday: VFR. Breezy.

Sunday Night: Mainly VFR, with local IFR possible. Chance SHRA.

Monday: Mainly VFR, with local IFR possible. Breezy. SHRA likely, chance TSRA.

Monday Night: Mainly VFR, with local MVFR possible. Breezy. Chance SHRA, chance TSRA.

Tuesday through Wednesday: VFR. Chance SHRA, slight chance TSRA.

MARINE

Forecaster Confidence Levels...

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

Winds and seas below small craft advisory levels through Saturday night. Light northerly winds tonight, shifting to light SW overnight. SW winds pick up to around 10-15 kt, and increasing to 15-20 kt Saturday overnight. Seas 3 ft or less through tonight, then increase to 3-4 ft.

Outlook /Saturday Night through Wednesday/...

Sunday: Winds less than 25 kt.

Sunday Night: Winds less than 25 kt. Chance of rain showers, slight chance of thunderstorms.

Monday: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Local rough seas. Chance of rain showers, slight chance of thunderstorms.

Monday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Chance of rain showers, chance of thunderstorms.

Tuesday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers, slight chance of thunderstorms.

Tuesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers, slight chance of thunderstorms.

Wednesday: Winds less than 25 kt. Slight chance of rain showers.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...High Risk for Rip Currents until 11 PM EDT this evening for MAZ022- 024. RI...None. MARINE...None.