textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes to the forecast.

KEY MESSAGES

- Mostly dry with above normal temperatures continuing through the weekend with humidity on the decrease.

- Expecting showers and thunderstorms Sunday night with the risk for severe weather remaining low.

- Seasonable temperatures and lower humidity returns through the first half of next week before a return to a more active pattern late-week.

DISCUSSION

KEY MESSAGE 1... Mostly dry with above normal temperatures continuing through the weekend with humidity on the decrease.

Temperatures remain in the upper 80s to low 90s through the weekend as an unseasonably warm airmass remains draped over New England. However, there will be a noticeable difference in the "feels like" temperatures compared to the last few days as dewpoints drop to the mid to upper 50s in the wake of a cold front pushing offshore this morning. With a ridging pattern moving into place aloft, expecting conditions to remain dry through most of Sunday.

KEY MESSAGE 2...Expecting showers and thunderstorms Sunday night with the risk for severe weather remaining low.

A cold front pushing into Southern New England Sunday night will increase the risk for showers and thunderstorms. Instability likely remains low heading into the overnight hours, despite elevated shear magnitudes, which will help to mitigate the risk for storms to turn severe. Uncertainty still remains in rainfall totals, with the latest suite of guidance indicating 2.0"+ PWATs could stretch anywhere from DelMarVa to Portland, ME. The ECMWF is the most aggressive, bringing 2.0-2.15" PWATs along the entirety of the I-95 corridor, but the GFS and Canadian guidance keep that deep moisture further south across Long Island. The latest round of ensembles and AI ensembles continue to keep the worst PWATs off our southern waters; however, there is a noticeable northward trend from run-to-run. Certainly something to keep an eye on as the day progresses.

KEY MESSAGE 3...Seasonable temperatures and lower humidity returns through the first half of next week before a return to a more active pattern late-week.

A cooler and much drier airmass then works into Southern New England Monday into Tuesday. Latest guidance shows 850 mb temps now dropping to around +8 to +10C, some 5-7C lower than we've been seeing. Highs are likely to drop into the low 80s, with dewpoints plummeting into the mid 40s to mid 50s, bringing about much more comfortable "feels like" temperatures. Temperatures will start to climb again heading into Wednesday, but are still seasonable in the low to mid 80s with still tolerable humidity levels.

More active weather looks to develop around Thursday or Thursday night, as a stronger disturbance aloft moves in and sweeps a cold front through Southern New England. This could bring a better shot at showers/storms, although it's still too early for specifics at this timeframe.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

Forecaster Confidence Levels...

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

18Z TAF Update...

Through Tonight: High confidence.

VFR. NW winds around 8-12 kts, but shift to W around 5-8 kt after 20z. Seabreezes expected to push in by 20z, with some areas already seeing local seabreezes, namely on the south shore and some spots along the south coast. Winds shift SW late tonight/early Sunday morning around 5-10 kt.

Sunday: High confidence.

VFR. SW winds increasing to 10-15 kt, with gusts to 25 kt.

Sunday Night: Moderate confidence.

Areas of MVFR to IFR possible with incoming SHRA and TSRA associated with a passing cold front. Winds prevailing out of the south from 10-15 kt sustained, shifting NW in the wake of the front. Gusts to 25 kt expected to continue through at least the first half of the nighttime period.

KBOS Terminal...High confidence in TAF. Late-day seabreeze expected to move in by 20z, as it has already reached the south shore.

KBDL Terminal...High confidence in TAF.

Outlook /Sunday Night through Thursday/...

Sunday Night: Mainly VFR, with local MVFR possible. Breezy. SHRA likely, chance TSRA.

Monday: VFR. Breezy.

Monday Night: VFR.

Tuesday: VFR. Breezy.

Tuesday Night: VFR.

Wednesday: VFR. Breezy. Slight chance SHRA.

MARINE

Forecaster Confidence Levels...

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

Through Sunday Morning...High confidence.

Seas generally 1-3 ft, except 3-4 ft across the far outer waters through Sunday morning. Otherwise, winds remain below SCA levels.

Outlook /Sunday Night through Thursday/...

Sunday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of seas approaching 5 ft. Rain showers likely, chance of thunderstorms.

Monday: Winds less than 25 kt.

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

Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft.

Tuesday Night: Winds less than 25 kt.

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

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...None.