textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes to the forecast.

KEY MESSAGES

- Scattered showers into this evening. Becoming drier overnight into Monday. Below normal temperatures continue.

- Spot showers and cooler temperatures linger through Tuesday.

- Lingering uncertainty regarding late week rain chances and temperatures.

DISCUSSION

KEY MESSAGE 1...Scattered showers into this evening. Becoming drier overnight into Monday. Below normal temperatures continue.

Cold pool aloft along with the passage of a mid level shortwave will bring scattered showers to our region into this evening. Can see a case where these showers persist longer past sunset due to cold pool aloft, but that has a lower probability of occurring. Some of the stronger showers, or even an isolated thunderstorm, could generate some graupel.

This low pressure moves offshore tonight, allowing weak high pressure to arrive from southeast Canada. This will bring drier weather, but also keep temperatures lower into Monday Night.

KEY MESSAGE 2...Spot showers and cooler temperatures linger through Tuesday.

The 500mb blocking pattern finally starts to push out over the Atlantic on Tuesday, but southern New England will stubbornly remain beneath an upper-level trough. As the heights slowly increase, temperatures aloft should also begin to increase, roughly a 5C increase at 850mb. This should support a return to seasonable temperatures, with highs in the low to mid 70s with local sea breezes. Coastal areas may end up a bit cooler in the upper 60s where the sea breeze sets up. Some model guidance is indicating a quick-moving piece of shortwave energy shifting southward across New England, resulting in low-end chances for a pop-up shower or two Tuesday afternoon.

KEY MESSAGE 3...Lingering uncertainty regarding late week rain chances and temperatures.

Uncertainty remains quite high for the second half of next week. Generally, guidance is favoring a warmer and drier solution, with indications that a low could spin up off the southeastern US coast and remain south of the 40N/70W benchmark. If this is the case, then we could see a several day stretch of dry conditions and temperatures soar well above seasonable levels, into the mid 80s, close to 90 in the CT River Valley. However, some members of the ensembles are showing the low could pass north of the benchmark, leading to more showery and cooler conditions brushing the South Coast and Cape/Islands.

AVIATION /00Z MONDAY THROUGH FRIDAY/

Forecaster Confidence Levels...

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

Tonight...Moderate Confidence.

Mainly VFR. Risk for scattered showers and an isolated thunderstorm or two should end by midnight. Potential for MVFR ceilings to push in after 06Z for the east coast/Cape terminals, including BOS. Light NW flow then turns N-NE.

Monday and Monday Night...High Confidence.

VFR. Light N to NE winds Monday becoming variable Monday Night. Low end chance (less than 10 percent) that some -SHRA develops and makes is as far south as BOS before the morning. Not confident enough to add to TAF at this time.

KBOS...Moderate confidence in TAF trends. Hit-and-miss showers remain through midnight with very low risk of an isolated thunderstorm in the vicinity of the terminal. Stratus deck towards the Monday morning push could have lower bases.

KBDL...High confidence in TAF.

Outlook /Tuesday through Friday/...

Tuesday through Thursday Night: VFR.

Friday: Mainly VFR, with local IFR possible. Breezy.

MARINE

Forecaster Confidence Levels...

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

Through Monday Night...High Confidence.

Wind speeds expected to be generally less than 20 kt through Monday, and less than 10 kt most of Monday night. Rough seas across the outer nearshore waters from yesterday will take longer to subside. Small Craft Advisories continue for these waters into tonight.

Outlook /Tuesday through Friday/...

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

Tuesday Night through Wednesday Night: Winds less than 25 kt.

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

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

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ250. Small Craft Advisory until 7 AM EDT Monday for ANZ254-255. Small Craft Advisory until 4 AM EDT Monday for ANZ256.