textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes.

KEY MESSAGES

- Rain overspreads the region Sunday afternoon and lasts through the night.

- Dry Monday then a few rounds of showers, first later Tuesday into Tuesday night, then around Friday into Saturday.

DISCUSSION

KEY MESSAGE 1...Rain overspreads the region Sunday afternoon and lasts through the night.

Some decent cooling tonight as we've managed to hold off the clouds through 2AM but moisture streaming out ahead of the approaching system will mean a partly to mostly cloudy start to the day by sunrise. Regional radar shows returns as far north as central NY but the heavier rain actually reaching the ground confined to PA for now. This precipitation shield will continue to expand north and east through Sunday overspreading western CT/MA by late morning/early afternoon and eastern MA by mid afternoon to early evening. Continuing to expect a widespread moderate rainfall as anomolous moisture originating from the Gulf makes its way overhead with isentropic forcing for ascent as well as a 30-45 kt LLJ. The core of this jet fortunately remains aloft and offshore to the south so while winds will be breezy, the main impact from this system is 12-18 hours of rainfall. When all is said and done we expect a quick 0.75"-1" of rainfall, as high as 1.5" along the immediate south coast.

KEY MESSAGE 2...Dry Monday then a few rounds of showers, first later Tuesday into Tuesday night, then around Friday into Saturday.

Brief respite from the rain comes Monday as most all of southern New England should be done with the rain by 8am with drier air and clearing skies following shortly behind on N/NW flow. After a brief warm-up Monday into the mid 60s and low 70s (CT Valley) 925mb temps quickly drop back to the 9-11C range on Tuesday (similar to Sunday). This means the return of highs in the low 60s. The brief drop in temps precedes a subtle shortwave passing to our north late Tuesday. Return flow ahead of the trough brings a surge in temps and dewpoints Tuesday night/Wednesday making Wednesday the warmest day of the week. There is potential for lower or even upper 70s, though confidence is low at this point that we'll get that warm. EPS ensembles have a >50% chance of >70F for much of the region while the GEFS odds are even better. A cold front then drops through sometime Wednesday bringing a much cooler end to the week. This frontal system brings rain around late Tuesday into early Wednesday then our next system doesn't arrive until around Friday.

AVIATION /06Z SUNDAY THROUGH THURSDAY/

Forecaster Confidence Levels...

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

06Z update...

Through 12Z: High confidence.

VFR. Light and variable winds.

Sunday and Sunday Night: High confidence.

VFR much of the day, lowering to MVFR then IFR from west to east, as early as 20Z for western terminals and 00z for eastern terminals. S/SE winds 5-10 kts with RA arriving from west to east generally between 16Z-21Z. RA continues overnight, exiting from west to east 10-14z.

Monday: High confidence.

N winds 5-10 kts. IFR cigs to start, lifting to VFR from west to east 12-17Z except for FMH/HYA/ACK which may linger through 21Z.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Monday Night through Thursday/...

Monday Night: Mainly VFR, with local MVFR possible.

Tuesday: Mainly VFR, with areas MVFR possible. Chance SHRA.

Tuesday Night: Mainly VFR, with local IFR possible. Breezy. Chance SHRA, slight chance TSRA.

Wednesday through Thursday: VFR. Breezy.

MARINE

Forecaster Confidence Levels...

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

Through Monday: High confidence.

Sunday winds increase again ahead of approaching low pressure, S/SW 10-15 kts gusting 15-20 kts. The remnants of Hurricane Isaias arrive Sunday PM, building seas 5 to 10 ft and wind gusts 23 to 30 knots by Sunday night. SCAs are in effect starting 8PM Sunday evening for the southern waters, 15-20 kts with gusts to 25kt possible, especially on the southern outer waters. Seas 6-9 ft on southern waters, 3-6 ft on the eastern waters.

Outlook /Monday Night through Thursday/...

Monday Night: Winds less than 25 kt. Areas of rough seas.

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

Tuesday Night: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Seas up to 5 ft. Chance of rain showers, slight chance of thunderstorms.

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

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

Thursday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Local rough seas.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 8 PM this evening to 8 PM EDT Monday for ANZ235-237-254>256.