textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes to the forecast.

DISCUSSION

KEY MESSAGE 1...Spotty light showers/drizzle tonight but much of the time it will be dry. More humid Sun with a few showers & t-storms possible especially near & west of the CT River Valley where an isolated strong-severe t-storm or two is possible.

Weak offshore low pressure will continue to result in moist/light NE low level flow into tonight. The result will be rather cloudy skies tonight with just some spotty light showers/drizzle at times...but this activity will be quite light with much of the time featuring dry weather. Some shortwave energy may allow for a few elevated heavier showers and perhaps a couple t-storms to develop near the southeast New England coast toward daybreak...mainly near the Cape and Islands. Some of the earlier model guidance has this activity further west...but latest indicating that the main risk for this will be towards the Cape and Islands closer to the shortwave energy.

Overnight low temps will only drop into the lower to middle 60s given clouds and an abundance of low level moisture. Areas of fog will be possible too...especially near the coast and in the Worcester Hills.

Again...we will need to watch for a few showers and isolated t- storms near the Cape and Islands early Sun morning. Otherwise...the main concern for a few showers and thunderstorms will be Sun afternoon/early evening given diurnal instability and shortwave energy to our west. The bulk of the height falls/forcing will be to our west. Therefore...greatest risk for a few showers and thunderstorms will be near and west of the CT River Valley Sun afternoon/early evening. Instability will be limited by a lot of cloud cover...but effective shear of 40+ knots will result in the low risk for an isolated strong to severe severe thunderstorm or two. Main severe weather risk would be a very localized damaging wind gusts and brief torrential rainfall. Greatest risk for this would near and west of the CT River Valley. That being said...much of the day will feature dry weather...but with a bit more humidity compared to this afternoon. Highs will be in the 70s to near 80.

KEY MESSAGE 2...Drier with a return to seasonable temperatures next week. Rain chances return Thursday/Friday.

A post-frontal air mass will usher in drier conditions and warmer temperatures with westerly winds Monday. As skies gradually clear from the dreary weekend, dewpoints will begin to drop slightly... into the upper 50s as opposed to the low to mid 60s we've been seeing. High pressure begins to slowly build Tuesday into Wednesday, prolonging the clear skies, drier weather, and warmer temperatures through the middle of the week. Chances for rain showers return Thursday and Friday as a low pressure system develops over the Great Lakes and meanders east through southern Ontario. Some uncertainty regarding the onset of the showers as there's little consistency in the global ensembles on the actual placement of the low as it tracks through Canada.

AVIATION /19Z SATURDAY THROUGH THURSDAY/

Forecaster Confidence Levels...

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

18z TAF Update...

This afternoon through tonight...Moderate confidence.

Mainly MVFR conditions at mid-aftternoon will deteriorate to generally IFR with localized IFR cigs/vsbys tonight. A few spotty showers/light drizzle and fog patches are possible at times too. Perhaps a few heavier showers and isolated t-storms graze areas towards the Cape and Islands toward daybreak Sun. Calm/light NE winds.

Sunday and Sunday night...Moderate confidence.

Mainly IFR with localized LIFR conditions Sun morning should improve to mainly MVFR-VFR levels by Sun afternoon/night. A few showers and t-storms are possible too with the greatest risk near and west of the CT River Valley during the afternoon/early evening. Light ENE gradually becoming light S by Sun night.

KBOS Terminal...Moderate confidence in TAF.

KBDL Terminal...Moderate confidence in TAF.

Outlook /Monday through Thursday/...

Monday: VFR. Breezy.

Monday Night: VFR.

Tuesday through Wednesday: VFR. Breezy.

Wednesday Night: VFR.

Thursday: Mainly VFR, with local IFR possible. Slight chance SHRA.

MARINE

Forecaster Confidence Levels...

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

Tonight through Sunday night...High confidence.

A wave of low pressure across the waters will be lifting into the Canadian Maritimes tonight. The pressure gradient though will remain weak enough to keep winds/seas below small craft advisory thresholds through Sunday night. Areas of fog will reduce visibilities for mariners at times especially later tonight into Sun morning.

Outlook /Monday through Thursday/...

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

Monday Night through Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft.

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

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

Wednesday Night through Thursday: Winds less than 25 kt.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...High Risk for Rip Currents until 6 PM EDT this evening for MAZ019- 022. RI...None. MARINE...None.