textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes to the forecast.

KEY MESSAGES

- Dry with below normal temperatures through Tuesday night.

- Above normal temps return Wed through the end of the week with high temps mainly in the 70s to near 80. A few showers possible sometime late Thu into early Fri...But dry weather dominates.

- Possible return for unsettled weather towards the back half of the upcoming weekend.

DISCUSSION

KEY MESSAGE 1...Dry with below normal temperatures through Tuesday night.

A large high pressure arrives from the west tonight. Gusty winds subside around sunset, then become light and variable late this evening. Expecting decent radiational cooling conditions, leading to low temperatures about 5-10 degrees below normal. The cooler conditions continue into Tuesday night with light E to SE winds. This high pressure should be over the North Atlantic Tuesday night, shifting winds more from the S to SW.

KEY MESSAGE 2...Above normal temperatures return midweek and last through the end of the week. Dry weather dominates, though a few showers are possible sometime in the late Thursday-early Friday timeframe.

High pressure continues to dominate this week's pattern, keeping generally dry conditions in place for southern New England. A strong upper level ridge set up across the southeast US will build partly into the northeastern US midweek before flattening out on its northern tier Thursday into Friday. A trough remains well to our north in Canada, and between these two large features, surface high pressure remains affixed over much of the northern and northeastern US. With a surge in warmer mid level air coming in from the west during this period, more above-normal temperatures make a return across southern New England; highs climb back up into the 70s and may creep into the low 80s.

High pressure loosens its grip over the region slightly late Thursday into Friday as a shortwave tracks toward the region. NAEFS guidance signaled a return of more anomalous moisture with the westerly flow, indicating PWATs about a standard deviation or two above normal for this time of year. Ahead of any possible showers with the incoming shortwave/frontal system, it may feel a bit more humid on Thursday. Guidance currently favors showers moving through the region late Thursday into Friday morning, though timing may fluctuate slightly between now and then. Dry conditions follow as drier air aloft is advected in, though the higher than normal temperatures may remain Friday afternoon before cooler temperatures take hold for Saturday.

KEY MESSAGE 3...Possible return for unsettled weather towards the back half of the upcoming weekend.

The ridge to our south appears to break down a bit going into the weekend, which may introduce increased chances for more unsettled conditions. Latest ensemble guidance hints at the second half of the weekend as the likely timeframe with strong low pressure tracking towards the region from the Plains and Great Lakes. Given how far out this event is, much will likely change over future updates.

AVIATION /18Z MONDAY THROUGH SATURDAY/

Forecaster Confidence Levels...

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

Through 00Z...High confidence.

VFR with gusty NW to N winds. Gusts up to 25 kt. Winds diminish toward sunset.

Tonight...High confidence.

Winds becoming calm/light from a N direction except N-NE at 5 to 15 knots along the immediate coast, Cape and Islands.

Tuesday...High confidence.

VFR. NE to E winds 5-10 kt becoming S to SE along portions of the immediate coast.

Tuesday night...High confidence.

VFR. Winds becoming light S to SW.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Wednesday through Saturday/...

Wednesday through Wednesday Night: VFR.

Thursday: Mainly VFR, with local MVFR possible.

Thursday Night: Mainly VFR, with local MVFR possible. Chance SHRA, slight chance TSRA.

Friday through Friday Night: Mainly VFR, with local MVFR possible.

Saturday: Mainly VFR, with local MVFR possible. Slight chance SHRA.

MARINE

Forecaster Confidence Levels...

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

High pressure moves over the waters late Tuesday, then offshore Tuesday night. Gusty NW to N winds diminish towards sunset tonight. Expecting relatively light winds and seas through Tuesday night. Marginal Small Craft Advisory conditions will end later this afternoon. The existing headlines may be canceled early. Will continue to monitor through this afternoon.

Outlook /Wednesday through Saturday/...

Wednesday through Thursday: Winds less than 25 kt.

Thursday Night: Winds less than 25 kt. Chance of rain showers, slight chance of thunderstorms.

Friday: Winds less than 25 kt. Slight chance of rain showers.

Friday Night through Saturday: Winds less than 25 kt.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 2 AM EDT Tuesday for ANZ231>235-237- 250-254>256.