textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes to the forecast since the last update.

KEY MESSAGES

- Unseasonable warmth and dry weather hold through at least mid to late week. Maximum temperatures peak in the upper 60s to low and mid 70s potentially putting daily records in jeopardy.

- Unsettled weather with continued warmer temperatures expected later this week heading into the weekend, which would feature periodic chances for rain.

DISCUSSION

KEY MESSAGE 1...Dry with anomalous warmth continuing into mid-week. Daily high in the upper 60s to low 70s, with isolated readings into the mid-70s flirting with daily records.

High confidence in continued dry and warm conditions through late week. Mid-level ridge remains dominant across the eastern CONUS, with the ridge axis moving over the region through at least Wednesday. Deep-layer subsidence combined with 925mb temps in the +11C to +14C range will yield an uncharacteristically warm airmass through Friday. Dry soil conditions and full solar insolation will continue the chance for high temps to overperform vs the NBM/MOS consensus. Thus, have bumped high temperatures on Wednesday and Thursday in the CT and Merrimack Valleys up 3-5 degrees. Doing so yields highs in the mid and even upper 70s across these regions. These readings would potentially challenge daily maximum temperature records both Wednesday and Thursday. Additionally, a SSW return flow will help to increase surface dew point temperatures into the 50s and 60s Wednesday night through Friday. This results in elevated nocturnal minimums and so both high and low maximum temperature records may be challenged through the week. More details in the climate section below.

KEY MESSAGE 2...Unsettled weather with continued warmer temperatures expected later this week heading into the weekend, which would feature periodic chances for rain.

A thermal ridge is expected to continue building over southern New England towards the midweek timeframe, which will be supportive of above-normal temperatures continuing for Wednesday and Thursday this week. 925 mb temperatures between 12-16C along with SW to S flow will bring the possibility of highs in the upper 60s into the low/mid 70s across southern New England Wednesday and Thursday. Ensembles have quite high probabilities of highs exceeding 70F Wednesday afternoon, and these remain somewhat elevated (up to 90% in southern parts of the coastal plain) for Thursday afternoon as well. Guidance doesn't indicate much with regards to a return to more mild temperatures until the second half of the weekend as the ridging shifts off to the east, but that could vary depending on how the approaching system evolves and tracks across the region.

Ensembles have continued to show a consensus with regards to the return of more unsettled weather for the second half of this week. A mid to upper level trough is expected to move in from the west, which will help advect in an anomalous moisture plume around 2 to 3 standard deviations above normal over southern New England. Closer to the surface, a frontal system associated with a previously more developed low pressure is expected to track across the region, bringing good chances for wetting rains towards the end of the week. Exact timing is still a bit uncertain, but latest guidance is leaning towards onset being Thursday evening at the earliest in western MA and CT, then tracking eastward through Friday. Showers may even linger into Sunday for parts of the region. Ensemble probabilities with regards to totals have not changed much from the overnight forecast, with probabilities for 24-hr totals >= 0.5" (period ending Saturday morning) generally between 30-70% across ensemble suites. Notably, though, the Canadian and ECMWF ensembles distribute these probabilities across the majority of southern New England as the front tracks from west to east, while the GEFS has a more focused footprint of higher probabilities and totals over Cape Cod and some of the coastal plain in SE MA. Given the spread in guidance, there is still decent uncertainty regarding the progression and development of the surface features that would really enhance rainfall totals and even introduce the chance for some rumbles of thunder.

AVIATION /10Z TUESDAY THROUGH SATURDAY/

Forecaster Confidence Levels...

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

12z TAF Update...High confidence.

VFR. This will persist through the middle of the week. Mid to high level cloudiness expected periodically. Winds generally SW at 5-15 kt in the afternoons. Low chance of MVFR/IFR and fog across the south coast and islands tonight into early Wednesday morning. Greatest chance will be between 06-12z Wednesday morning.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Wednesday through Saturday/...

Wednesday: VFR. Breezy.

Wednesday Night: VFR.

Thursday: Mainly VFR, with local MVFR possible. Breezy. Slight chance RA.

Thursday Night: Mainly VFR, with local MVFR possible. Chance RA.

Friday: Mainly VFR, with local IFR possible. RA likely, slight chance TSRA.

Friday Night: Mainly MVFR, with local IFR possible. RA, slight chance TSRA.

Saturday: Mainly VFR, with local MVFR possible. Chance RA.

MARINE

Forecaster Confidence Levels...

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

Through Wednesday...High confidence.

An upper level ridge of high pressure will keep winds/seas below small craft advisory thresholds through the middle of the week. Nonetheless...we may have some SW wind gusts of 20+ knots at times particularly nearshore during the afternoons. This may result in some choppy seas at times...but thinking we should remain below the need for headlines. Greatest chance of 20+ knot winds is this afternoon across the SE waters.

Outlook /Wednesday through Saturday/...

Wednesday: Winds less than 25 kt. Patchy fog. Local visibility 1 to 3 nm.

Wednesday Night: Winds less than 25 kt.

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

Thursday Night: Winds less than 25 kt. Seas up to 5 ft. Chance of rain.

Friday: Winds less than 25 kt. Seas up to 5 ft. Rain likely, slight chance of thunderstorms.

Friday Night: Winds less than 25 kt. Seas up to 5 ft. Rain, slight chance of thunderstorms.

Saturday: Winds less than 25 kt. Rough seas up to 9 ft. Rain likely, slight chance of thunderstorms.

CLIMATE

Persistent unseasonable warmth over the next several day will challenge calendar-day record highs and record high minimums across southern New England climate sites.

Daily Record Highs to Watch:

Boston (BOS): Wednesday 78F (1987)|Thursday 79F (1994)

Hartford/Bradley (BDL): Wednesday 78F (1987)|Thursday 75F (2022)

Providence (PVD): Wednesday 77F (1987)|Thursday 75F (1994)

Worcester (ORH): Wednesday 74F (1987)|Thursday 73F (1994)

Daily Record Lows to Watch:

Boston (BOS): Thursday 56F (1994)|Friday 57F (2020)

Hartford/Bradley (BDL): Thursday 55F (1994)|Friday 56F (2020)

Providence (PVD): Thursday 56F (1994)|Friday 58F (2020)

Worcester (ORH): Thursday 55F (1994)| 55F (2020)

BOX WATCHES/WARNINGS/ADVISORIES

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