textproduct: Boston / Norton

WHAT HAS CHANGED

Small craft headlines issued for all waters overnight and especially Thursday for gusty southwest winds and rough seas.

KEY MESSAGES

- Warming trend continues with unseasonably mild conditions Thursday. Widely scattered showers possible tonight into Thursday.

- A strong cold front brings rainy and cooler conditions Friday into the weekend.

DISCUSSION

KEY MESSAGE 1...Warming trend continues with unseasonably mild conditions Thursday. Widely scattered showers possible tonight into Thursday.

Weak subsidence behind a departing northern stream shortwave and high pressure to our south will bring dry conditions through today. Despite sunshine giving way to increasing clouds today, persistent south to southwest winds will continue the warming trend.

Another weak shortwave passes by tonight. Not looking like there is much low level humidity to work with. As a result, expecting widely scattered light rain showers after midnight into Thursday. The greatest risk will be north of the Mass Pike, simply due to proximity to the mid level forcing. Increasing risk for light rain later int he day as a cold front approaches from the northwest.

Becoming unseasonably mild Thursday as increasing SW flow develops ahead of an approaching cold front. Expect breezy conditions with 20- 30 mph gusts at times.

KEY MESSAGE 2...A strong cold front brings rainy and cooler conditions Friday into the weekend.

A strong cold front approaches southern New England Thursday night into early Friday morning, bringing another widespread, soaking rain. Ensemble guidance is currently indicating a surge of moist air ahead of the front, enhancing PWATs to 1.10"-1.25"... roughly 200-250 percent of normal for this time of year. Currently thinking this rain would last through the night and into a good portion of Friday morning, but it's still a little early to nail down exact timing... regardless, southern New England could potentially see up to 0.5" of rain.

Post-FROPA on Friday, a drier airmass will push into the region. Winds pick up as the boundary layer becomes well mixed throughout the day, with 20-30mph winds possible. As this drier airmass moves through, it will also bring dropping 850mb temps with ensembles indicating temps dropping down to -16C... roughly a -17C temperature anomaly. High temps likely occur early Friday morning before falling throughout the day with strong cold air advection. Highs struggle into the upper 30s to lower 40s on Saturday and Sunday before rebounding into the low 50s for the start of the next work week.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

Forecaster Confidence Levels...

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

18Z TAF Update...

Through 00Z...High Confidence

VFR. Winds becoming more steady out of the south/south southwest around 10 knots. Still an outside chance for a sea-breeze at BOS for a couple hours between 18-20Z.

Tonight...High confidence.

Mainly VFR conditions...But can not rule out brief marginal MVFR cigs possible toward daybreak along with a brief spot shower or two. S-SW winds may gust to between 20 and 25 knots near the coast late tonight with a strengthening LLJ. We have also included LLWS for the Cape/Islands as that southwest LLJ strengthens to around 50 knots.

Tomorrow...High confidence.

VFR conditions dominate outside perhaps some brief marginal MVFR cigs during the early-mid morning hours. SW wind gusts of 20-30 knots develop. Generally dry weather...but a few spot showers possible mainly early in the morning and perhaps later in the day near the NH border. Strong LLWS possible over the south coast with 40-50 knots of shear to 2000 feet.

Tomorrow Night...Moderate Confidence.

Conditions deteriroate to MVFR tomorrow night with -RA overspreading the region from west to east. Southwest winds becoming northwest between 06 and 12Z Friday.

KBOS Terminal...Moderate confidence.

Increased confidence that a sea-breeze will not occur today, but there does remain a slight chance for some onshore flow between 18-20Z.

KBDL Terminal...High confidence.

Outlook /Thursday Night through Monday/...

Thursday Night: Mainly MVFR, with areas VFR possible. Windy with local gusts up to 30 kt. RA likely.

Friday: VFR. Breezy. Chance RA.

Friday Night: VFR. Breezy.

Saturday through Saturday Night: VFR.

Sunday: VFR. Breezy.

MARINE

Forecaster Confidence Levels...

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

Today Through Thursday...High confidence.

Winds/seas remain below small craft advisory thresholds today. SW winds increase again late tonight and especially Thursday with 25 to 30 knot wind gusts. Rough seas should redevelop across the coastal waters with a south to southwest exposure during the day Thursday. Small Craft Advisories have been issued.

Outlook /Thursday Night through Monday/...

Thursday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Rain.

Friday: Winds less than 25 kt. Areas of rough seas. Chance of rain.

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

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

Saturday Night through Sunday: Winds less than 25 kt.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 8 AM Thursday to midnight EDT Thursday night for ANZ230-236. Small Craft Advisory from 5 AM Thursday to 8 AM EDT Friday for ANZ231>234-251. Small Craft Advisory from 5 AM Thursday to 5 PM EDT Friday for ANZ235-237. Small Craft Advisory from 11 PM this evening to 2 PM EDT Friday for ANZ250. Small Craft Advisory from 5 AM Thursday to 8 PM EDT Friday for ANZ254>256.