textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes to the forecast. 18Z aviation update.

KEY MESSAGES

- Unseasonable warmth continues for the next couple of days.

- Wet and unsettled weather returns Thursday into this weekend. Continued above normal temperatures before cooler conditions arrive Sunday and beyond.

DISCUSSION

KEY MESSAGE 1...Unseasonable warmth continues for the next couple of days.

High pressure centered to our SE will maintain southwest winds through tonight, becoming more southerly on Thursday. As of 1 PM this afternoon, no record highs have been tied or broken but temperatures are within a few degrees of the records. See the climate section below for more details.

There may be record maximum low temperatures for Thursday and Friday, and high temperatures for Thursday at least approach records for the day.

KEY MESSAGE 2...Wet and unsettled weather returns Thursday into this weekend. Continued above normal temperatures before cooler conditions arrive Sunday and beyond.

Chances of rain begin on Thursday, mainly over the western zones, but no impacts expected during the day. A cold front slowing its eastward progression then enters the region late Thursday night. A wave of low pressure is progged to form along this front as a closed 500mb low approaches the Northeast. This combination will help to bring a prolonged period of rainfall with the highest overall chances of rain occurring Friday morning through early Saturday morning.

Rainfall could be heavy at times Friday and Friday night. PWATs will likely be in the range of 1.50 to 1.75 inches and perhaps enough CAPE over SE zones for a rumble of thunder and localized heavier downpours. Extra synoptic lift is anticipated during this period as well with the region progged to be in the right entrance region of an upper jet streak. The higher rainfall amounts are anticipated over the SE zones. Fortunately, we've been very dry and flash flood guidance is high. Still not expecting flash flooding to be an issue, though potential rain amounts have increased from the previous forecast and will need to see if guidance trends wetter and is more consistent with the location of the axis of highest precip. Some poor drainage/urban flooding is possible, especially given the leaves blocking drainage this time of year. There continues to be a marginal risk within the Excessive Rainfall Outlook for Friday into Saturday.

Rain chances drop off Saturday morning but showers will continue to be possible through Sunday morning with a cyclonic flow overhead; nothing like Friday/Friday night though. NW flow ushers in a colder, albeit closer to normal, airmass for early next week with high temperatures returning to the 50s.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

Forecaster Confidence Levels...

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

Today...High confidence.

VFR. Winds SSW/SW at 5-15 kt. Few gusts to 15-25 kts for coastal terminals through this afternoon.

Tonight...Moderate confidence.

VFR to start, likely falling to MVFR and IFR after 06z due to lower ceilings. S to SSW winds overnight at 5-10 kt, with some areas in the higher elevations seeing occasional 15-20 kt gusts after 06z.

Thursday...Moderate confidence.

Areas of MVFR and IFR to start. Slow improvement to VFR from SE to NW. IFR could linger across the higher terrain of central and western MA into evening.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Thursday through Monday/...

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

Friday: MVFR/IFR conditions possible. RA, slight chance TSRA eastern terminals.

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

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

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

Sunday: VFR. Breezy. Slight chance RA.

MARINE

Forecaster Confidence Levels...

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

Through Thursday night...High confidence.

Surface high pressure stays positioned SE of the waters into Thursday. Gusts for the rest of the day will be 20-25kt, but there will probably be a few gusts 25kt+ mainly near the Cape/Islands as this has already occurred at a few mesonet locations. Gusts likely aren't consistent enough 25kt+ over a period to warrant Small Craft Advisories at this time. Winds diminish tonight, and then again anticipating isolated gusts 25kt+ Thursday afternoon for the same areas.

Outlook /Thursday Night through Sunday/...

Thursday Night: Winds less than 25 kt. Seas building up to 4 ft. Chance of rain.

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

Friday Night: Winds less than 25 kt. Local rough seas. Rain, slight chance of thunderstorms. Local visibility 1 to 3 nm.

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

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

Sunday: Wind gusts around 25 kt. Chance of rain in the morning.

CLIMATE

Persistent unseasonable warmth over the next couple of days 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.