textproduct: Boston / Norton

WHAT HAS CHANGED

Tweaked sky cover and temperatures for today this morning. Increased rain chances and winds for the late week/weekend storm as confidence increases.

KEY MESSAGES

- A drier, warmer, and increasingly sunny Monday. Low clouds and rain showers return Tuesday/Tuesday night with a rumble of thunder possible.

- Drying out Wednesday, and especially Thursday, under high pressure.

- Next, stronger storm system arrives Friday into Saturday.

DISCUSSION

KEY MESSAGE 1...A drier, warmer, and increasingly sunny Monday. Low clouds and rain showers return Tuesday/Tuesday night with a rumble of thunder possible.

Latest satellite data showed some breaks in the clouds from southeast NH, across north central MA, into portions of northern CT. More stubborn lower clouds remained across southeast MA and much of RI. Tweaked the timing of this clearing for today. This timing will be crucial for temperatures as well. Full sunshine should be able to boost temperatures towards the upper 60s to lower 70s with 850mb temperatures of +10-15C. The longer the clouds linger, the more likely temperatures stay in the 60s. Tweaked afternoon temperatures down slightly this morning, but they should still be a least 10 degrees higher across interior southern New England than Sunday.

Things change tonight as a low center over the Great Lakes approaches while high pressure sits over Nova Scotia. This initially turns surface flow out of the northeast advecting cooler, saturated air onshore making for low clouds with patchy drizzle to start Tuesday. This brings highs back into the 60s. The warm front lifts north Tuesday afternoon bringing scattered rain showers which continue until the cold front drops through sometime Wednesday. SNE will be socked in with clouds all of Tuesday and Tuesday night as moisture remains trapped under a strong inversion. Could even see some rumbles of thunder given some weak elevated instability above that inversion. Elevated dewpoints will also lead to mild lows, in the upper 50s and lower 60s.

KEY MESSAGE 2...Drying out Wednesday, and especially Thursday, under high pressure.

Wednesday things begin to dry out behind the cold front and the inversion mixes out allowing for a mix of clouds and sun. However, a stronger reinforcing cold front brings a much cooler and drier airmass for Thursday as high pressure arrives. 925mb temps drop to near 6C leading to highs only in the low 60s under mostly sunny skies.

KEY MESSAGE 3...Next, stronger storm system arrives Friday into Saturday.

Our next storm, this one likely stronger than the mid week system, originates out west Thursday. A low forms in the lee of the Rockies, phasing with another low over the Great Lakes as it is swept east by a northern stream trough. It then strengthens as it moves over or near New England Friday into Saturday. This pulls a lot of moisture into the region and with good dynamics including potential for a strong 45-55kt LLJ and favorable placement beneath the RRQ of a 160kt upper jet, we should see a windy and very rainy Friday-Saturday. Timing and other details are uncertain at this time, but confidence in at least a decently strong weather system is increasing.

AVIATION /13Z MONDAY THROUGH FRIDAY/

Forecaster Confidence Levels...

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

Today: High confidence in trends, but moderate on timing improvement.

IFR ceilings continue across RI and southeast MA. VFR Anticipating slow improvement to IFR ceilings toward MVFR by 14-16z from northwest to southeast, then trending SCT VFR by 17-19z (periodic MVFR ceilings thru 19z). North winds around 5-10 kt, decreasing in speed to around 5 kt by afternoon.

Tonight: High confidence in trends but moderate on timing backdoor cold front.

VFR early tonight; then a backdoor cold front progresses southward from NH/ME. Timing approximately 02-04z for BED, and around 04-07z for the remaining TAFs. This will bring lowering ceilings again into the MVFR-IFR range, light -RA and winds turning NE around 5-10 kt, strongest near the coast.

Tuesday: Moderate confidence.

MVFR-IFR ceilings, with lighter rains or drizzle. Possible MVFR-VFR optimism by mid to late afternoon. NE/E winds around 5-10 kt, turning SE/S by afternoon and increasing to around 10 kt.

KBOS Terminal...High confidence in trends, moderate confidence in timing. Slow improvement from IFR by 14-15z, then MVFR thru 17z before trending MVFR/VFR. Backdoor cold front brings NE winds late tonight (after 04z Tue).

KBDL Terminal...High confidence in TAF.

Outlook /Tuesday Night through Friday/...

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

Wednesday through Thursday: VFR. Breezy.

Thursday Night: VFR. Chance SHRA.

Friday: VFR. Windy with local gusts up to 30 kt. SHRA.

MARINE

Forecaster Confidence Levels...

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

Through Monday: High confidence.

The remnants of Hurricane Isaias are currently working their way across the southern waters. Seas 5 to 10 ft and wind gusts 20-30 knots. SCAs are in effect 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.

Monday night: High confidence.

NE winds 10-15 kts with gusts 20-25 kts on the eastern waters. Seas 3-5 ft.

Tuesday: High confidence.

SE winds 10-15 kts with increasing gusts to 20 kts. Seas 3-5 ft. RA over the eastern waters.

Outlook /Tuesday Night through Friday/...

Tuesday Night: Moderate risk for Small Craft Advisory winds with gusts up to 25 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.

Wednesday Night: Winds less than 25 kt. Seas up to 5 ft. Slight chance of rain showers.

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

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

Friday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Local rough seas. Rain showers likely, slight chance of thunderstorms.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 11 PM EDT this evening for ANZ235- 237. Small Craft Advisory from 8 PM this evening to 2 AM EDT Wednesday for ANZ250. Small Craft Advisory until 8 PM EDT Wednesday for ANZ254. Small Craft Advisory until 8 AM EDT Tuesday for ANZ255-256.