textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes.

KEY MESSAGES

- Drier and warmer Friday with only some scattered afternoon showers and a mix of clouds and sun.

- A cold front brings the return of rain Sunday night and Monday, perhaps lingering into Tuesday.

- Drying and warming trend toward Wed/Thu.

DISCUSSION

KEY MESSAGE 1...Drier and warmer Friday with only some scattered afternoon showers and a mix of clouds and sun.

Finally some mid level height rises today as weak ridging builds in with building high pressure at the surface. Even so, the trough is slow to exit and cyclonic flow with a cold pool aloft (500 mb temps - 10 to -12C) will, after more sun/clearing in the morning, allow for diurnal cumulus to pop us as well as some widely scattered afternoon showers. That being said, the airmass is drier under backing NW flow and most locations will be dry. Regardless, the airmass will be warming allowing highs to get back into the upper 70s and low 80s. Light winds mean coastal seabreezes keep the immediate coastline comfortably in the mid 70s.

KEY MESSAGE 2...A cold front brings the return of rain Sunday night and Monday, perhaps lingering into Tuesday.

After drier and warmer (mid to upper 80s) weather on Saturday under a brief ridge of high pressure the patterns again begins to break down toward the end of the weekend/start of the work week. This is also where we begin to see model consensus decrease, so confidence in exact timing details is low. That being said, there is good agreement that an upper trough will dig into the east coast pulling a deep plume of subtropical moisture north ahead of it and into New England centered around Monday. The GFS is the more amplified solution with a stronger southern cut-off low lingering into next week and higher rainfall totals for SNE. A key component will be the cold front which crosses the region on Monday focusing the best forcing for ascent coincident with PWATs over 2". Considering the rain some locations have gotten this week (5+ inches in localized spots), while it doesn't appear overly concerning WRT flooding it is worth watching. There remains a question as to how long rain lingers, potentially into Tuesday for some locations.

KEY MESSAGE 3...Drying and warming trend toward Wed/Thu.

Western Atlantic high pressure then builds west as mid level ridging follows and we'll see a drier and steadily warming period Wed/Thu. This may be a brief respite before more unsettled weather on the horizon.

AVIATION /12Z FRIDAY THROUGH TUESDAY/

Forecaster Confidence Levels...

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

12z TAF Update:

Today...High confidence.

VFR. Light N winds with coastal sea breezes. Slight chance of some scattered showers. Low probability of TS towards central MA and into RI. Included as PROB30s at ORH and PVD for the time being, but would not be surprised to see those change to SHRA or erased altogether depending on how any showers pop up today.

Tonight...High confidence.

VFR for most with highest chances for MVFR towards the Cape and Islands. Some IFR possible in any fog that develops tonight, especially towards the Cape and Islands, along with in the CT River valley. Light SW winds generally at or below 5 kt, going calm towards the interior.

Saturday...High confidence.

VFR. SW winds 5-10 kts.

KBOS Terminal...Moderate to high confidence in TAF. Seabreezes develop Fri 14-15z. Low probability for SHRA this afternoon; too low to include in TAF at this time.

KBDL Terminal...High confidence in TAF. Chance for IFR visby in any fog that develops tonight between 10z-12z.

Outlook /Saturday Night through Tuesday/...

Saturday Night: VFR.

Sunday: VFR. Breezy. Slight chance SHRA.

Sunday Night: VFR. Chance SHRA, slight chance TSRA.

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

Monday Night: VFR. Breezy. Chance SHRA.

Tuesday: VFR.

MARINE

Forecaster Confidence Levels...

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

Winds N/NW tonight as the low pressure just offshore continues shifting into the Maritimes. Seas continue to diminish heading into the weekend, 2-3 feet. Winds become lighter Friday and shift more to the SW heading into Friday night and Saturday. Fog expected to develop over much of the southern waters and off the east coast of Cape Cod.

Outlook /Saturday Night through Tuesday/...

Saturday Night through Sunday: Winds less than 25 kt.

Sunday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers, slight chance of thunderstorms.

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

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

BOX WATCHES/WARNINGS/ADVISORIES

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