textproduct: Boston / Norton

WHAT HAS CHANGED

Gale Warnings hoisted for Buzzards Bay, Cape Cod Bay and Nantucket Sound later tonight into Thursday morning.

KEY MESSAGES

- Increasing clouds today especially across northern MA. Highs in the middle 70s-lower 80s. A few brief light showers possible toward evening especially across western and northern MA.

- Gusty SW winds tonight into Thu and becoming humid as well. Brief round of showers tonight into early Thu especially in northern MA. Unseasonably warm Thu...Highs middle to upper 80s.

- Dry and very pleasant weather follows Fri into Sat. Highs in the 70s with low humidity. Quite cool Fri night/Sat am with lows in the 40s to the lower 50s and perhaps even some upper 30s in the normally coolest low lying locations.

- Above normal temps return for the first half of next week with a brief round of scattered showers possible late Sat night-Sun am.

DISCUSSION

KEY MESSAGE 1...Increasing clouds today especially across northern MA. Highs in the middle 70s-lower 80s. A few brief light showers possible toward evening especially across western and northern MA.

Large high pressure moves off the coast today as a cold front and shortwave energy approach from the west. This will result in increasing southwest flow today and a gradual increase in humidity. We also do expect to see an increase in clouds in the warm advection pattern and developing southwest LLJ as the day wears along. In fact... we may see a few brief light showers toward evening especially across western and northern MA. High temperatures will mainly be in the middle 70s to the lower 80s. A southwest breeze will also kick in during the afternoon with gusts on the order of 15 to 25 mph.

KEY MESSAGE 2...Gusty SW winds tonight into Thu and becoming humid as well. Brief round of showers tonight into early Thu especially in northern MA. Unseasonably warm Thu...Highs middle to upper 80s.

As the actual cold front approaches from the west tonight into early Thu the southwest LLJ will increase further. All the guidance is in fairly good agreement in a southwest LLJ peaking between 45 and 55 knots over this time. Bufkit soundings also indicate some modest mixing too. This should yield southwest wind gusts of 20 to 30 mph with a few brief gusts near 35 mph in the Worcester Hills and near the I-95 corridor. However...the strongest winds will likely be towards the Cape/Islands particularly in the climatologically favored spots with this setup near Buzzards Bay/Upper Cape. GFS/NAM soundings near KFMH indicating brief 35-45 mph wind gusts and not out of the question a few spots briefly flirt with Wind Advisory criteria.

Lastly...the other issue will be potential for some showers. Pwats are quite impressive on the order of 2+ inches tonight into early Thu. However...the better dynamics will be to our north and the soundings indicate some mid level dry air which will be limiting factors. Nonetheless...we still expect a brief round of showers tonight into early Thu especially across northern MA. However...they will not last long at a given location. In fact...plenty of sunshine should develop on Thu and 925T on the order of +20C to +22C should yield highs in the middle to upper 80s in many locations. Westerly wind gusts of 20-30 mph are also expected with a bit of humidity too...especially during the first half of the day.

KEY MESSAGE 3...Dry and very pleasant weather follows Fri into Sat. Highs in the 70s with low humidity. Quite cool Fri night/Sat am with lows in the 40s to the lower 50s and perhaps even some upper 30s in the normally coolest low lying locations.

Post frontal airmass will result in beautiful weather Fri into Sat with low humidity. Plenty of sunshine expected both days with highs in the 70s along with very comfortable humidity. High pressure overhead will allow for lows in the the 40s to the lower 50s with even some upper 30s possible in the normally coolest low-lying locations.

KEY MESSAGE 4...Above normal temps return for the first half of next week with a brief round of scattered showers possible late Sat night- Sun am.

High pressure moves off the coast for the second half of the weekend as a warm front crosses the region. This may bring a brief period of scattered showers to the region late Sat night into Sun morning. Its main impact will be a southwest flow of warmer air working back into the region. Ensembles are in agreement in above normal height fields and 2 meter temp anomalies for the first half of next week. This supports above normal temps for the first half of next week...mainly in the upper 70s to the middle 80s.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

Forecaster Confidence Levels...

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

12z TAF Update...

Today...High confidence.

Low end VFR or borderline MVFR through most of the day. Light ESE winds becoming S-SW at 8-14 knots this afternoon. Winds may gust to between 20 and 25 knots this afternoon...strongest of those towards the south coast.

Tonight and Thursday...High confidence.

Mainly VFR but some brief MVFR conditions mainly late tonight into early Thursday in a round of brief showers. SW winds of 10 to 20 knots with gusts up to 30 knots especially across the Worcester Hills as well as the I-95 corridor. Strongest winds will be towards the Cape/Islands...especially in the vicinity of the Upper Cape where brief SW wind gusts of 35-40 knots are possible.

SW winds become more W during the day on Thu with gusts on the order of 20 to 30 knots.

KBOS Terminal...High confidence in TAF. ESE sea breeze develops this morning. The sea breeze should kick out in the 18z-20z time frame with the wind turning S.

KBDL Terminal...High confidence in TAF.

Outlook /Thursday Night through Sunday/...

Thursday Night through Friday: VFR. Breezy.

Friday Night through Saturday: VFR.

Saturday Night: VFR. Slight chance SHRA.

Sunday: 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.

Today through Thursday...High confidence.

An approaching cold front will result in a developing southwest level jet later today. The southwest low level jet peaks later tonight into early Thu when 925 mb winds reach between 45 and 55 knots. While not all of this will mix down...we expect widespread southwest wind gusts of 25 to 35 knots where have continued strong small craft headlines for most waters...but brief gale force gusts are certainly possible. We did upgrade Buzzards and Cape Cod Bay as well as Nantucket sound to Gale Warnings. Based on pattern recognition...a brief period of SW wind gusts of 35-40 knots appears reasonable and is supported by Bufkit soundings.

Outlook /Thursday Night through Sunday/...

Thursday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Chance of rain showers.

Friday through Saturday Night: Winds less than 25 kt.

Sunday: Winds less than 25 kt. Chance of rain showers.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 8 PM this evening to 8 PM EDT Thursday for ANZ230-235>237-250-251-254>256. Gale Warning from 10 PM this evening to noon EDT Thursday for ANZ231>234.