textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes in this forecast package.

KEY MESSAGES

- Areas of patchy fog this morning followed by a quick warm up

- Unseasonably warm temps Sun through Wed with near record high temps into the 90s possible Tue and/or Wed.

- Strong to severe thunderstorms possible by Tue with perhaps a better potential by Wed but a lot needs to be sorted out.

- Seasonable temperatures return by next Thu and Fri.

DISCUSSION

KEY MESSAGE 1...Areas of patchy fog this morning followed by a quick warm up

A mid-level ridge aloft has slowly built over southern New England this evening. Mostly clear skies has allowed near- surface temperatures to cool enough to match dew point temperatures in the low to mid 40s. With a shallow inversion in place, the boundary layer has slowly saturated with fog development at a few locations in southern New England, mainly in the radiator areas. Expect patchy fog development to continue through sunrise. Thereafter, any areas of fog will lift after sun rise. West/southwest flow will begin to advect a warmer air mass over the region, beginning a period of above normal temperatures that will persist through the middle of next week. With diurnal mixing and 925 hPa temps rising to 18-20C, we can expect high temperatures in the mid to upper 70s for most locations in southern New England this afternoon with near 80 possible in the CT River Valley. The Cape and Islands will be cooler given the proximity to the ocean with highs in the upper 60s/low 70s. Overall a very pleasant spring day to start the weekend.

KEY MESSAGE 2...Unseasonably warm temps Sun through Wed with near record high temps into the 90s possible Tue and/or Wed.

High confidence continues in a pattern change to unseasonable warm temperatures for the first half of next week and potentially flirting with record highs on Tue/Wed. GEFS/EPS guidance continue to show a building Bermuda High pressure system resulting in above to well above normal height fields.

W-SW flow should push high temps into the 80s on Sun away from the Cape and Islands. A weak backdoor cold front may bring briefly cooler temps Mon...mainly on the immediate coast. Highs Mon on the immediate coast probably in the upper 60s and 70s while 80+ risk will be confined to the interior. The hottest days look to be Tue and/or Wed depending on the timing of a cold front. 925T near +24C should result in the potential for high temperatures to climb into the 90s away from any modified marine influences. This may result in record high temperatures being challenged at least in areas away from the south coast.

KEY MESSAGE 3...Strong to severe thunderstorms possible by Tue with perhaps a better potential by Wed but a lot needs to be sorted out.

Quite the ways out there...especially for a convective forecast. That being said...there are some signals for potentially strong to severe thunderstorms later Tue and perhaps a better chance by Wed. This will be dependent upon the timing of a cold front...but given anomalous/near record warmth the potential is there. In fact...much of our machine learning guidance indicates some modest severe weather probabilities for a Day 4-5 forecast...so this is certainly something to watch.

KEY MESSAGE 4...Seasonable temperatures return by next Thu and Fri.

The long range guidance is in good agreement in the return of seasonable temperatures by Thu and Fri behind the mid-week cold front.

AVIATION /12Z SATURDAY THROUGH WEDNESDAY/

Forecaster Confidence Levels...

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

12Z TAF Update...High confidence

Today through Tomorrow...High Confidence

VFR conditions through tomorrow, except LIFR at ACK through 13z today when FG lifts out. Steady southwest winds around 10 knots today with some gusts of 20+ knots possible during the mid- afternoon hours. Southwest winds should be strong enough to fend off a sea- breeze. Steady west winds continue overnight and become more west/northwest on Sunday.

KBOS...High confidence in TAF

KBDL...High confidence in TAF.

Outlook /Sunday Night through Wednesday/...

Sunday Night through Monday Night: VFR.

Tuesday: VFR. Breezy. Slight chance SHRA, slight chance TSRA.

Tuesday Night: VFR. Breezy.

Wednesday: VFR. Breezy. Chance SHRA, slight chance TSRA.

MARINE

Forecaster Confidence Levels...

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

SCAs remain in effect on most waters as easterly swell brings elevated seas in the 4-7 ft range tonight. Winds shift more SW tonight into Saturday, getting up to around 15 kt sustained Saturday afternoon. Gusts to 25 kt possible then as well. Fog possible again tonight over the waters.

Given the continued elevated seas and increase in winds tomorrow, SCAs have been extended through Saturday into part of Saturday night. Winds and seas are expected to remain elevated then, and possibly into Sunday morning.

Outlook /Sunday Night through Wednesday/...

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

Monday through Monday Night: Winds less than 25 kt.

Tuesday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of seas approaching 5 ft.

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

Wednesday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from noon today to 8 PM EDT this evening for ANZ231>234. Small Craft Advisory until 2 AM EDT Sunday for ANZ235-237-251. Small Craft Advisory until 4 AM EDT Sunday for ANZ250-254>256.