textproduct: Boston / Norton

WHAT HAS CHANGED

Flood watch has been cancelled. Small craft advisories for Boston Harbor and Narragansett Bay have also been taken down as conditions begin to improve.

KEY MESSAGES

- Slowly improving weather overnight and Tuesday as the nor'easter weakens and moves away

- Warm and Dry conditions arrive Wednesday through Friday followed by a chance for rainy and unsettled conditions this weekend

DISCUSSION

KEY MESSAGE 1...Slowly improving weather overnight and Tuesday as the nor'easter weakens and moves away.

Although the low level swirl around the center of the nor'easter south of Long Island looks impressive on satellite imagery, the storm is quickly weakening as it's starting to move more quickly to the northeast. Still a good amount of moisture, wrapped around the circulation, producing a fairly large area of light rainfall. However as the dynamics weaken, the rainfall intensity is also on a downward trend. Expect most areas will see less than 1/2" of additional rainfall from this point forward. Models are all in good agreement in taking the low across the Cape overnight and then into the Gulf of Maine on Tuesday. Surface winds will slowly transition from NNE to NNW and then NW by Tuesday morning - except across our southern coastal waters and Nantucket, which will see winds go from the SE to SW and eventually W since the low center will pass north of those areas. Model forecast cross-sections indicate low level moisture will be slow to leave tomorrow, so expect a generally mostly cloudy day. Better chances for some afternoon sunshine will be across western areas. There is no blob of cold air that will come in behind the nor'easter, and in fact 925mb temperatures will be a little warmer than they were today. So given that and some breaks of sunshine, temperatures will be in the mid to upper 60s for most, and a few locations - especially in the CT River Valley - could hit 70F.

Also, given the downward trends in rainfall, have gone ahead and cancelled the Flood Watch. Although some minor flooding is still expected along portions of the Taunton River, we don't anticipate any increase in risk for flooding across the area.

KEY MESSAGE 2...Warm and Dry conditions arrive Wednesday through Friday followed by a chance for rainy and unsettled conditions this weekend.

A mid-level ridge builds across the southeastern CONUS this week, while surface high pressure settles south of the region Wednesday through Friday, leading to a stretch of quieter and warmer weather. Guidance hints at a weak northern-stream shortwave Wednesday night into early Thursday, followed by a secondary shortwave Thursday night into Friday. PWATs Wednesday night into Thursday remain below 1.2 inches and do not align particularly well with the best forcing. Outside of a brief light shower, would anticipate more clouds than anything. PWATs increase to around 1.5 inches Thursday night with the passage of the secondary weak shortwave, when a few light showers could brush the region. No significant impacts are anticipated with either disturbance. Temperatures trend warmer through the middle and latter half of the week, though the latest guidance has trended somewhat cooler compared to previous runs. Highs generally return to the lower and middle 70s, with Thursday potentially the warmest day as temperatures reach the middle to upper 70s. No notable cold is expected overnight, with lows generally falling into the 50s.

Forecast becomes a bit more interesting by late next week as a strong continental high pressure system arrives from SE Canada. Guidance shows a rather sharp drop in temperatures with 850 temps falling from +15-17C Friday to +4-6C on Saturday. Beyond this front, guidance is beginning to come into better agreement with depicting a strong area of low pressure across SE Canada on Sunday. There remains a variety of solutions with the GFS/ICON depicting secondary cyclogenesis along a frontal boundary near the Carolinas and the ECMWF/CMC leaning more towards a strong frontal boundary. In any case, the second half of the weekend looks wet and unsettled. Behind this feature, guidance depicts a much colder airmass moving in from Canada with 850mb temps falling below zero later Monday through Wednesday. These mid- level temps would support highs in the 40s and 50s with nighttime lows possibly falling into the 30s depending on radiational cooling.

AVIATION /00Z TUESDAY THROUGH SATURDAY/

Forecaster Confidence Levels...

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

00z TAF Update...

Overall moderate confidence.

IFR to occasionally LIFR conditions will continue through the evening and much of the overnight. Although areas of -RA and -SHRA will slowly wind down later this evening, low ceilings and BR will persist in most areas. Probably some -DZ mixed in as well. The timing of the -SHRA and lower visibility/ceiling conditions are just estimates.

As we get into Tuesday morning, we should see improving conditions to at least MVFR in most areas, and perhaps VFR conditions developing by early afternoon across western areas. Guidance suggests low level moisture will remain in place, resulting in widespread ceilings of 2000-2500ft for most areas much of the day. Basically what you see this afternoon across western NY and PA will be what is over our area tomorrow.

VFR conditions should build in Tuesday night.

KBOS Terminal...Moderate confidence in TAF. NNE winds continue to fall and will shift to the NNW in the coming hours. Mostly IFR conditions overnight with periods of LIFR likely through at least 09z. Gradual improvement towards MVFR by tomorrow afternoon.

KBDL Terminal...Moderate confidence in TAF.

Outlook /Tuesday Night through Saturday/...

Wednesday through Wednesday Night: VFR.

Thursday through Thursday Night: VFR. Breezy.

Friday: VFR. Slight chance SHRA.

Friday Night: VFR. Chance SHRA.

Saturday: VFR.

MARINE

Forecaster Confidence Levels...

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

Overall high confidence.

The nor'easter is weakening and beginning to move more quickly to the northeast. The center will pass over Cape Code overnight and then move into the Gulf of Maine for tomorrow. As that happens, winds will continue to diminish. Seas will also continue to subside, but that process will take a bit longer than the winds, especially for the outer waters off the eastern MA coasts. High pressure does move across the region later tomorrow, and then will set up off the US east coast and provide an extended period of SW winds for the middle through end of the week.

Outlook /Tuesday Night through Saturday/...

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

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

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

Friday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers.

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

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...Coastal Flood Advisory until midnight EDT tonight for MAZ007- 015-016-019-022>024. RI...None. MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ231>235-237. Small Craft Advisory until 2 PM EDT Tuesday for ANZ250-251. Small Craft Advisory until 8 AM EDT Tuesday for ANZ254. Small Craft Advisory until 2 AM EDT Tuesday for ANZ255-256.