textproduct: Boston / Norton

WHAT HAS CHANGED

The River Flood Warning for the Taunton River at Bridgewater was extended into Wednesday night based on latest NERFC river forecasts. Otherwise no significant changes.

KEY MESSAGES

- Dry, with temperatures trending above normal through the end of the week

- Next chance for showers arrives Friday with a sweeping cold front followed by a sharp drop in temperatures.

- A secondary, sharp temperature drop is expected with potential for more showers heading into next week.

DISCUSSION

KEY MESSAGE 1...Dry, with temperatures trending above normal through the end of the week

Surface high pressure and a mid-level ridge have started to build in, bringing a warmer and drier airmass to southern New England. This will enhance the warming trend throughout the week, allowing temperatures to climb into the low 70s today, mid to upper 70s by Thursday, and near 80 by Friday. Despite the high pressure, lingering low-level moisture from the previous weekend's nor'easter will lead to quite a bit of cloud cover over the next few days.

KEY MESSAGE 2...Next chance for showers arrives Friday with a sweeping cold front followed by a sharp drop in temperatures.

The next round of showers arrives sometime Friday as a low pressure system moves across Ontario and Quebec Thursday and Friday and a trailing cold front sweeps through New England Friday. Some uncertainty still remains on the exact timing of when the front will pass, but latest guidance has honed in on the evening/overnight hours into Saturday morning. Regardless, not expecting much QPF out of this... less than a quarter inch likely. Most guidance is showing the front stalling out somewhere south of our waters,

Once the low moves through Quebec, a rather strong continental high pressure system will build over Ontario, sinking those +4C to +6C 850mb temperatures down into New England and sharply dropping surface temperatures through the weekend... overnight temps likely drop into the upper 30s to low 40s and daytime highs in the mid 60s.

KEY MESSAGE 3...A secondary, sharp temperature drop is expected with potential for more showers heading into next week.

Towards the second half of the weekend and into early next week, ensemble guidance is suggesting the potential for a deepening low to sweep across the James Bay, possibly bringing another round of shower to southern New England heading into Monday morning. A strong high pressure system builds in right on the heels of the low, bringing a secondary shot of even colder air to New England. 850mb temperatures could drop to near or just below 0C by Tuesday, supporting surface highs in low 50s with nighttime lows possibly falling into the 30s.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

Forecaster Confidence Levels...

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

18z TAF Update:

Rest of Today...High confidence.

SCT-BKN MVFR/VFR through 00z. Light northerly winds turning SW late in the day; ESE seabreezes BOS and PVD continue through 00z.

Tonight...High confidence.

Mainly VFR, though patchy fog/mist could possibly develop with the wet ground and light southwest winds. Greatest chance for fog and mist across interior terminals like BDL.

Thursday...High confidence.

VFR. SW wind 8-12 kt.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...Moderate confidence in TAF.

Outlook /Thursday Night through Monday/...

Thursday Night: VFR. Breezy.

Friday through Friday Night: VFR. Breezy. Chance SHRA.

Saturday through Saturday Night: VFR.

Sunday: VFR. Slight chance SHRA.

MARINE

Forecaster Confidence Levels...

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

Overall high confidence.

High pressure builds off the east coast, setting up southwest flow across the region today and continuing into Friday. Seas build towards 5 feet by late Thursday/early Friday across the southern waters due to the sustained southwest winds.

Outlook /Thursday Night through Monday/...

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

Friday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft.

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

Saturday: Winds less than 25 kt. Seas up to 5 ft.

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

Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers.

BOX WATCHES/WARNINGS/ADVISORIES

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