textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes to the forecast.

KEY MESSAGES

- Mainly dry with seasonable temperatures through this weekend.

- Periodic chances for scattered showers & thunderstorms with summerlike humidity both return in the late Mon through Wed timeframe...perhaps lingering into Thu.

DISCUSSION

KEY MESSAGE 1...Mainly dry with seasonable temperatures through this weekend.

A surface high pressure will dominate our weather through this weekend. It will remain relatively cool for late July with comfortable humidity for most. Once of the more uncertain aspects to this forecast will be the winds.

Gusty W to NW winds early this afternoon will continue to subside into this evening. Not as confident this will lead to an east coast sea-breeze for most, as the gradient wind would be more likely to keep it just offshore. As this high pressure moves overhead tonight into Friday, winds become very light/calm. Have greater confidence in sea-breezes developing Friday.

KEY MESSAGE 2...Periodic chances for scattered showers & thunderstorms with summerlike humidity both return in the late Mon through Wed timeframe...perhaps lingering into Thu.

The next shortwave trough approaches the region from the west in the late Mon-Wed timeframe. This will allow southerly flow to bring typical summerlike humidity back to southern New England. This will also bring a return to period chances of showers and thunderstorms to the region in the late Mon-Wed time frame...perhaps lingering int Thu if trough is slower to depart. As is typical this time of year...that entire period will not be a washout with many hours of dry weather. While specific timing is impossible to pinpoint...afternoon/evenings will be favored given diurnal heating/instability. Pwats on the order of 1.50 to 2" will bring the risk of localized heavy rainfall within any convection.

Temperatures fairly seasonable for this time of year. Lows may be a bit above normal with highs a touch below normal given the increasing low level moisture for the middle of next week. Nothing though really out of the ordinary for July standards.

AVIATION /18Z THURSDAY THROUGH TUESDAY/

Forecaster Confidence Levels...

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

Through 00Z...High confidence.

VFR. Winds WNW to NW for most terminals 5-10 kts. Sea-breezes likely for the coastal areas developing 18-20Z as NW winds weaken.

Tonight through Friday Night...High confidence.

VFR. Light to calm winds overnight out of the S to SW, shift more towards S to SE for Friday, then finally more E to NE late Friday night.

KBOS Terminal...High confidence in TAF.

Lower confidence in a sea-breeze developing after this afternoon. Gusty NW winds are more likely to keep the sea-breeze front over the harbor. There is still a low chance for a brief sea-breeze right before the evening push.

KBDL Terminal...High confidence in TAF.

Outlook /Saturday through Tuesday/...

Saturday: VFR. Breezy.

Saturday Night through Sunday Night: VFR.

Monday: VFR. Slight chance SHRA, slight chance TSRA.

Monday Night: VFR. Chance SHRA.

Tuesday: Mainly VFR, with local IFR possible. Breezy. Chance SHRA, chance TSRA.

MARINE

Forecaster Confidence Levels...

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

Through Friday Night...High confidence.

Winds and seas continue to subside into tonight as a high pressure moves over the waters Friday. Lingering rough seas across the coastal waters behind a cold front. Did tweak the end timing of the current Small Craft Advisories to account for observed trends.

High Surf Advisory remains in effect for exposed southern coastlines through this evening. Prolonged period of higher seas and SW flow have increased the risk for rip currents. The higher risk decreases Friday.

Outlook /Saturday through Tuesday/...

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

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

Sunday Night through Monday: Winds less than 25 kt.

Monday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers.

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

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...High Surf Advisory until 8 PM EDT this evening for MAZ020>024. RI...High Surf Advisory until 8 PM EDT this evening for RIZ006>008. MARINE...Small Craft Advisory until 7 PM EDT this evening for ANZ254- 256. Small Craft Advisory until 11 PM EDT this evening for ANZ255.