textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes.

KEY MESSAGES

- Dry and milder Friday, then scattered showers developing Friday night.

- Dry this weekend, other than brief scattered showers early Sat morning. Seasonable weekend with highs in the middle 50s to the lower 60s.

- Summer-like warmth arrives early next week. Highs well into the 60s to the lower 70s Mon and potentially 80+ Tue. Duration of warmth is uncertain, with backdoor cold front lurking nearby midweek. Other than a few brief showers possible at times...dry weather dominates.

DISCUSSION

KEY MESSAGE 1...Dry and milder Friday, then scattered showers developing Friday night.

High pres lingers just off the SNE coast tonight before moving further offshore Fri. One more chilly night tonight, although not as cold as last night with lows in the 30s. Then we expect a notable temp recovery Fri, especially away from the south coast as SW flow brings warmer low level temps. Soundings do show a rather shallow boundary layer to about 950 mb where temps increase to 12-14C. With mostly sunny skies, this will support highs into the upper 60s in the interior, but SW flow will keep temps in the 50s near the south coast. SW winds will gust to 20-25 mph at times, up to 30 mph on Cape Cod.

Then Fri night decent mid level shortwave passes to the north with a modest low level jet developing ahead of an advancing cold front. Modest forcing confined with PWATs briefly increasing to around 1" ahead of the front will lead to scattered showers moving across the region during the late evening and overnight. The front is expected to move offshore late Fri night with drying by Sat morning.

KEY MESSAGE 2...Dry this weekend, other than brief scattered showers early Sat morning. Seasonable weekend with highs in the middle 50s to the lower 60s.

A low amplitude northern stream short wave and attending cold front move through the region early Sat, 06z to 12z west to east. Rainfall amounts will be very light and short-lived (1-3 hrs) in a given location. Moisture/PWAT plume is centered over Cape and Islands 12z Sat, with rapid drying thereafter as PWATs plunge to 40% of normal and surface dew pts fall into the 20s during the afternoon. Hence, scattered showers over Cape Cod and Islands at 12z Sat, exit rapidly offshore with dry weather overspreading the region after sunrise from NW to SE. Modest post frontal CAA with 850 mb temps cooling off to -2C to +2C by 18z Sat. Model soundings support mixing beyond 850 mb, yielding NW winds 15-25 mph. Thus, a cool NW breeze but abundant sunshine and deep blyr mixing will help offset with max temps in the upper 50s high terrain, to the lower 60s in the coastal plain, including Boston- Providence corridor. Given the deep blyr mixing, we will lower the surface dew pts given fire weather concerns. 1035 mb high builds overhead Sat night, yielding ideal radiational cooling. Thus, we will adjust mins to reflect the cooler MOS guidance here. Other than a chilly Sunday morning, very pleasant weather continues Sunday afternoon with rising heights over SNE. Surface ridge overhead will promote chilly afternoon seabreezes for the coastal plain. However, seasonable temps away from the coast, with highs 55-60, but only upper 40s to lower 50s along/near the shore.

KEY MESSAGE 3...Summer-like warmth arrives early next week. Highs well into the 60s to the lower 70s Mon and potentially 80+ Tue. Duration of warmth is uncertain, with backdoor cold front lurking nearby midweek. Other than a few brief showers possible at times...dry weather dominates.

High amplitude east coast ridge will provide multiple warm days next week. Some uncertainty on duration of warmth, with potential backdoor cold front sometime mid to late next week. All ensemble systems offer low to moderate probs of 80+ Tue/Wed/Thu next week. However, at this time range, low predictability regarding timing and amplitude of short wave energy riding over the top of the East Coast Ridge and resulting backdoor cold fronts. This large spread in timing and amplitude is evident when evaluating individual ensemble members, along with AI models and the UKMET. Thus, the overall theme remains warm to very warm, along with mainly dry weather next week. There could be a brief interruption to the summer-warmth sometime around midweek, especially eastern MA given potential for a backdoor cold front, but confidence remains low on details. As for precip chance, a warm front will cross the region Sun night with the potential for a brief round of scattered showers. A few brief showers also possible mid week. Otherwise, dry weather dominates.

AVIATION /18Z THURSDAY THROUGH TUESDAY/

Forecaster Confidence Levels...

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

18z TAF Update...High confidence.

Mainly VFR through Fri, but SCT-BKN MVFR cigs may develop tonight. Areal coverage uncertain. SW gusts increase to 20 kt during Fri, with some G25 kt possible over Cape Cod. Areas of MVFR cigs developing late Fri night as scattered showers move through.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Saturday through Tuesday/...

Saturday: VFR. Breezy.

Saturday Night through Sunday: VFR.

Sunday Night: VFR. Breezy. Chance SHRA.

Monday: VFR. Windy with local gusts up to 30 kt. Slight chance SHRA.

Monday Night: VFR. Breezy. Slight chance SHRA.

Tuesday: VFR.

MARINE

Forecaster Confidence Levels...

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

Tonight through Friday night...High confidence.

A period of S wind gusts to 25 kt expected over NE MA waters this evening as low level winds increase and we have issued a SCA for these waters. Otherwise, light S-SW winds tonight increasing Fri with gusts to 20-25 kt developing during the afternoon and evening, especially over easter n MA waters. Light seas building to 5 ft over outer waters late Fri and Fri night. SCAs may be needed on some of the waters.

Outlook /Saturday through Tuesday/...

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

Sunday: Winds less than 25 kt. Seas locally approaching 5 ft.

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

Monday: Strong winds with gusts up to 30 kt. Areas of rough seas. Slight chance of rain showers.

Monday Night: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Slight chance of rain showers.

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

CLIMATE

Since we are potentially looking at our first 80-degree temperatures of the season early next week, here are some stats regarding average, earliest, and latest 80-degree temperatures.

Note that Hartford (Bradley) already hit 80 degrees this year back on March 31.

Boston: Average May 4, Earliest March 21, 1921, Latest June 16, 1924

Providence: Average May 4, Earliest March 20, 1945, Latest June 18, 1924

Hartford: Average April 28, Earliest March 9, 2016, Latest June 15, 1924

Worcester: Average May 4, Earliest March 15, 1990, Latest June 10, 1997

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 7 PM this evening to 2 AM EDT Friday for ANZ250-251.