textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes to the forecast.

KEY MESSAGES

- Mostly pleasant conditions on tap today until scattered showers move in later this afternoon and linger through the night.

- A sharp temperature drop is then expected for the start of the week followed by a return to dry, fall-like conditions.

DISCUSSION

KEY MESSAGE 1...Mostly pleasant conditions on tap today until scattered showers move in later this afternoon and linger through the night.

High pressure sitting over Maine will push into the Canadian Maritimes today, lending clear skies and cooler temperatures in the mid to low 60s for most of the day. A weak low then pushes east off the DelVarVa coast, bringing chances for showers to southern New England into the afternoon and overnight hours. Most of the latest guidance suite is indicating this will be a scattered event, with the heaviest rain bands staying offshore; however, the NAMNST and HREF are the most aggressive, not only indicating more of a stratiform rain, but in bringing some heavier bands inland. Highest confidence in heaviest rainfall remains along the south coast, Cape, and Islands, especially after 7PM and through the overnight hours.

KEY MESSAGE 2...A sharp temperature drop is then expected for the start of the week followed by a return to dry, fall-like conditions.

A deepening low is expected to track east across the James Bay and into Quebec Monday with a strong high pressures system over the Great Lakes following on its heels for the start of the work week. A significantly cooler airmass sinks south into New England, with the latest guidance indicating the 540mb line sinking well into northern New England, possibly as far south as southern NH, by early Tuesday morning. 850mb temperatures likely drop to near or just below 0C by Tuesday morning. Most guidance also suggests 925mb temps drop to as low at +1C or +2C. This would support surface highs near 60 degrees with nighttime lows possibly falling into the 30s through Wednesday.

A brief warm-up to the low 70s may be possible late week as the high pushes east Thursday. Otherwise, prolonged west-southwest flow will mark the return of drier conditions and seasonable temperatures to southern New England for the end of the week.

AVIATION /08Z SUNDAY THROUGH THURSDAY/

Forecaster Confidence Levels...

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

06z TAF Update...

Tonight...High confidence.

Generally VFR, except some patchy BR possible in the usual radiator spots. N/NE winds less than 10 kts.

Sunday and Sunday Night...High confidence in trends, moderate confidence in timing of showers.

VFR through much of Sunday with increasing mid-level clouds. Ceilings lower to MVFR from SW to NE between 20z-00z. Showers become more widespread Sunday evening and overnight, reducing visibilities to 3-5SM at times. Ceilings lower to MVFR/IFR overnight into early Monday morning.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Monday Night through Thursday/...

Monday Night through Tuesday: VFR. Breezy.

Tuesday Night: VFR.

Wednesday through Thursday: VFR. Breezy.

MARINE

Forecaster Confidence Levels...

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

Through Monday...High confidence.

Calm conditons continue through the first half of Sunday. High pressure located near the Great Lakes tracks east- northeast across northern New England Sunday as weak low pressure develops near the Mid- Atlantic coast Sunday afternoon, then tracks northeast toward southern New England Sunday night.

Seas are generally 2-4 feet through much of Sunday, though build to 5+ feet across the outer, ocean waters Sunday night. East to northeast winds are generally 10-15 knots, with gusts increasing to 20-25 knots Monday. SCA will likely be needed for Monday night into Tuesday.

Outlook /Monday Night through Thursday/...

Monday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas.

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

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

Wednesday through Thursday: Winds less than 25 kt.

BOX WATCHES/WARNINGS/ADVISORIES

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