textproduct: Boston / Norton

WHAT HAS CHANGED

Forecast remains on track.

KEY MESSAGES

- Showers move out of southern New England by 7-8AM. Drier and slightly cooler afterwards.

- High astronomical tides and up to one-foot of storm surge could cause minor coastal flooding for the evening high tides tonight and Tuesday night.

- Near seasonable temperatures and dry conditions followed by more unsettled weather at the end of the work week.

DISCUSSION

KEY MESSAGE 1...Showers move out of southern New England by 7-8AM. Drier and slightly cooler afterwards.

Any lingering showers this morning should move out of southern New England by 7-8 AM. In the wake of the cold front, skies clear and temperatures fall to more seasonable... upper 70s across the interior to low to mid 80s across RI and the eastern coastal plain. Dewpoints will also be on the decrease, down to the 50s across most of the region. High pressure starts to build in as a surface ridge develops. Lows across the interior tonight may fall to the low 50s with mid/upper 50s into the coastal plain. Winds go light to calm with clearer skies, lending some favorability to a possible radiational cooling setup.

KEY MESSAGE 2...High astronomical tides and up to one-foot of storm surge could cause minor coastal flooding for the evening high tides tonight and Tuesday night.

Astronomical tides will be peaking around 12.0 feet at Boston Harbor this evening and will remain elevated into Tuesday night. Latest storm surge forecast data from P-ETSS and Stevens Institute continue to indicate about a half to up to one foot of storm surge through Tuesday evening's tide cycle.

This is a low-ceiling coastal flooding scenario, with splashover or at worst minor coastal flooding in the usual vulnerable shoreline roads (including but not limited to Easy Street in Nantucket and Morrissey Blvd in Boston). Given the influx of visitors to Southern New England who may not be as familiar with coastal flooding, we opted to continue Coastal Flood Statements for much of the southern and eastern coast with a Coastal Flood Advisory remaining in effect for Nantucket through Tuesday night.

KEY MESSAGE 3...Expecting a more active pattern to return during the second half of the week.

Temperatures will start to climb again heading into Wednesday, but are still seasonable in the low to mid 80s with tolerable humidity levels. Long-range guidance continues to disagree regarding precipitation chances Wednesday, with the GFS (and ensembles) bringing light shower chances back Wednesday during the daytime while the ECMWF and Canadian (and ensembles) hold off until Thursday. Regardless, more active weather looks to develop around Thursday or Thursday night, as a stronger disturbance aloft moves in and sweeps a cold front through Southern New England. This could bring higher chances for showers and/or thunderstorms.

Expecting a front to push offshore sometime on Friday, bringing clearing skies and dry conditions to southern New England as we head into the weekend. Temperatures should climb to slightly above normal, in the mid to upper 80s, but dewpoints should return to comfortable levels, in the upper 40s to upper 50s.

AVIATION /15Z MONDAY THROUGH FRIDAY/

Forecaster Confidence Levels...

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

15z TAF Update:

Monday: High confidence. Moderate for sea breeze potential.

Conditions improve to VFR behind the front as NW flow develops. Generally NW winds 8-12 kts. Occasional gusts up to 20 kts, mainly at BDL and ORH. Potential for a sea breeze for the coastal terminals after 19Z; however, confidence is lower.

Monday Night: High Confidence.

VFR. NW winds 5-10 kts.

Tuesday: High Confidence.

VFR. Light NW winds less than 10 kts. Local sea breezes.

KBOS Terminal...Moderate confidence in trends. Outside shot at a seabreeze after 20z, but it would hinge on NW winds subsiding early enough which is not likely.

KBDL Terminal...High confidence in trends.

Outlook /Tuesday Night through Friday/...

Tuesday Night through Wednesday Night: VFR.

Thursday: Mainly VFR, with local MVFR possible. Windy with local gusts up to 30 kt. Chance SHRA, slight chance TSRA.

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

Juneteenth: VFR. Breezy. Slight chance SHRA.

MARINE

Forecaster Confidence Levels...

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

Monday....High confidence.

Seas remain 4-5 ft across the southern waters, but drop to 2-4 ft across the northern waters. Likewise, wind gusts remain around 20 kts across the southern waters and drop to near 10 kts across the northern waters.

Monday Night...High confidence.

Localized parts of the southern outer waters early Monday night may see seas to 5 ft before settling to 2-4 ft overall heading into Tuesday morning. Winds remain NW, sustained between 10-15 kt with not much in the way of wind gusts.

Tuesday...High confidence.

Seas generally 2-4 ft. NW winds turning SW with some gusts up to 20 kts possible.

Outlook /Tuesday Night through Friday/...

Tuesday Night: Winds less than 25 kt.

Wednesday through Wednesday Night: Winds less than 25 kt. Slight chance of rain showers.

Thursday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Local rough seas. Slight chance of rain showers.

Thursday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 8 ft. Chance of rain showers.

Juneteenth: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Chance of rain showers.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...Coastal Flood Advisory until 2 AM EDT Tuesday for MAZ024. RI...None. MARINE...None.