textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes to the forecast.

KEY MESSAGES

- Summerlike temperatures with tolerable humidity levels and dry weather through the workweek.

- Unsettled and cooler conditions late this weekend into early next week.

DISCUSSION

KEY MESSAGE 1...Summerlike temperatures with tolerable humidity levels and dry weather through the workweek.

High pressure both at surface and aloft will continue to govern Southern New England's weather through the rest of the workweek. Full sunshine is expected through at least Friday, with an increase in 925-850 mb temps both Thursday and on Friday. By Friday, 850 mb temps rise to around +13 to +15C. This combo of full sun, SW flow and warming lower-atmospheric temps will bring about a spell of above-normal temperatures running about 10 degrees warmer compared to early- June climatology. Highs away from the coast should top out in the mid/upper 80s (to low 90s CT and Merrimack Valleys) tomorrow and upper 80s to low/mid 90s on Friday. The drier air and lack of recent significant rainfall could support slightly warmer temps. At night, lows should drop into the mid 50s to low 60s. Other than along the South Coast where mixing looks more shallow, mixing should be pretty good on both days and that should keep humidity levels to around tolerable levels (e.g. dewpoint temps in the 50s). Overall summerlike temperatures but without the "stickiness" we tend to see with temps this warm. That's reflected in the heat indices, which are similar to or even lower than the air temps. SW winds should also be just strong enough to preclude eastern and southern- coastal seabreezes.

KEY MESSAGE 2...Unsettled and cooler conditions late this weekend into early next week.

Gaining confidence that most of Saturday will remain dry for most across southern New England. Also gaining confidence that Sunday will features showers for most. Drier weather looking more likely for early next week.

Latest guidance has come into better agreement with the overall synoptic pattern heading into this weekend, but there still remains some timing differences. One of these is the timing of a cold front approaching our region from northern New England and upstate NY. Continue to think this front will only reach southern NH/VT late in the day Saturday. That said, still a risk for scattered showers or thunderstorms during the afternoon just from the heat and humidity.

Showers becoming more likely Saturday night into Sunday as the aforementioned front slowly moves south across our region. Expecting drier conditions to gradually develop from north to south Monday. Mainly dry weather expected Tuesday into Wednesday.

Above normal temperatures Saturday will be noticeably lower Sunday, but Monday actually looks like the coldest day in this part of the forecast. Temperatures should trend back above normal by Wednesday.

AVIATION /00Z THURSDAY THROUGH MONDAY/

Forecaster Confidence Levels...

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

Tonight: High confidence.

VFR. North winds around 5-10 kt interior SNE airports through early evening, with seabreezes along the southern and eastern coasts, trending to SW around 5-10 kt through tonight. There is an outside shot at patchy fog or stratus bringing local IFR conditions to ACK but seems too unlikely for a TAF mention.

Thursday and Thursday Night: High confidence, though moderate on seabreeze potential.

VFR through 12z Friday. SW winds around 8-12 kt, with occasional gusts to 20-22 kt restricted to the Cape and Islands. Thinking SW winds prevail even at BOS and PVD who are more prone to seabreezes, but if winds can stay light enough they could briefly turn onshore/SE starting 16-17z. Winds remain SW 5-10 kt overnight.

KBOS...High confidence in TAF. SW winds remain around 10 kt through the morning hours Thursday. There is a window for a possible SE seabreeze around 16-21z but think SW winds prevail much of Thursday.

KBDL...High confidence in TAF.

Outlook /Friday through Monday/...

Friday through Friday Night: VFR.

Saturday: VFR. Breezy. Slight chance SHRA, slight chance TSRA.

Saturday Night: Mainly VFR, with local IFR possible. Breezy. Chance SHRA, slight chance TSRA.

Sunday: VFR. Breezy. SHRA likely, chance TSRA.

Sunday Night: VFR. Breezy. SHRA likely, slight chance TSRA.

Monday: 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 Thursday Night: High confidence.

Winds and seas should remain below SCA criterion through Thursday night. SW winds develop tonight at around 10-15 kt and should run around 15-20 kt Thursday. There is a low risk for Small Craft Advisory-level gusts around the Cape and Islands waters (Buzzards Bay/Vineyard and Nantucket Sounds) which typically blow stronger on SW flow. Seas 3 ft or less on all waters.

Outlook /Friday through Monday/...

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

Friday Night: Winds less than 25 kt. Seas up to 5 ft.

Saturday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft.

Saturday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Chance of rain showers.

Sunday: Winds less than 25 kt. Seas up to 5 ft. Rain showers likely, slight chance of thunderstorms.

Sunday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Chance of rain showers, slight chance of thunderstorms.

Monday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Seas up to 5 ft. Chance of rain showers.

BOX WATCHES/WARNINGS/ADVISORIES

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