Hyannis, MA Weather

What Has Changed

Marine headlines (Gale Warnings and Small Craft Advisories) have been extended through Wednesday night. Gusty northeast winds and rough seas continue. Otherwise, no significant changes.

Key Messages

- A distant Nor'Easter brings hazardous marine conditions, with gusty northeast breezes over land through Thursday. Other than some light rain showers on Wednesday in southeast New England, dry weather otherwise prevails.

- Prolonged stretch of dry weather Friday into early next week, except for a brief risk of showers across the eastern coastal waters Friday morning. Cooler Friday, followed by moderating temperatures into early next week.

Discussion

KEY MESSAGE 1...A distant Nor'Easter brings hazardous marine conditions, with gusty northeast breezes over land through Thursday. Other than some light rain showers on Wednesday in southeast New England, dry weather otherwise prevails.

Nor'Easter located well offshore (well south of 40N/70W) will continue to slowly meander nearly in place through most of Wednesday, then gradually peel off toward the NE and ENE later on Wednesday and into the waters south of the Canada Maritimes Thursday. Meanwhile, an expansive area of high pressure continues to govern much of New England with sunny skies, but is driving a tight NE gradient bringing breezy to gusty conditions, with the strongest gusts (35-40 mph) closer to Cape Cod and Nantucket.

There remains no major changes to the forecast, messaging and projected impacts from this system specific to Southern New England. The main impacts continue to be primarily over the southern/southeast waters with building rough seas and gale- force winds, with some beach erosion to east-facing beach exposures. Over land, the main impacts continue to be breezy to gusty northeast winds, in particular for southeast New England. These gusts should again fall into the 20-25 mph range over the interior, but reach into the 25-35 mph range for most of the coastal plain away from Cape Cod, and could gust up to 40 mph for Nantucket. Guidance does show more in the way of cloud cover for Wednesday and Thursday for the southeast New England coastal plain, with light rain showers as well, but there ends up being several hours of dry weather in between. Best chance for rain ends up being on Wednesday, as the circulation pulls away and a reinforcing shot of cooler air as high pressure builds back southward into Thursday.

Expect plentiful sunshine away from the coasts, with seasonably mild days (upper 50s to lower 60s) and cool nights (mid 30s to low 40s). Near the eastern and southeast coasts, cloud cover and stiff onshore breezes will result in a narrower range in temperatures, with lows in the mid 40s to low 50s, and highs in the mid to mid/upper 50s. It will feel a bit cooler with the northerly breezes though.

KEY MESSAGE 2...Prolonged stretch of dry weather Friday into early next week, except for a brief risk of showers across the eastern coastal waters Friday morning. Cooler Friday, followed by moderating temperatures into early next week.

Once the nor'easter departs farther offshore, a large high pressure over eastern Canada takes over. This high pressure shifts south across the Northeast, reaching the central Appalachians by Monday. Friday looks to be the coldest day of this portion of the forecast, followed by a warming trend this weekend into at least Monday. Some question as to how quickly a cold front moves past our region Monday night into Tuesday. At present, Tuesday looks like we'll be on the colder side of this front. However, this timing is not locked in yet.

Aviation

Forecaster Confidence Levels...

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

Through Tonight: High confidence.

VFR. Potential exists for lower-end VFR ceilings to arrive by the pre-dawn hours, thinking it will now be slightly later Wednesday morning. North to northeast winds gusting to 25-35 kt for the Cape and Islands terminals, but remaining around 20-25 kt elsewhere. Gusts should run about 5 kt lighter tonight with less mixing.

Wednesday and Wednesday Night: High confidence, though moderate on rain shower coverage in southeast New England.

Low clouds (VFR/fringe-MVFR range) and possible light -RA for the Cape airports through this period, although visibilities will not be restricted and rain may not be necessarily persistent with dry periods in between. Away from the Cape and Islands, SCT-BKN VFR decks prevail to I-95, with decreasing cloudiness further into the interior. NE winds resume around 25-35 kt for the Cape and Islands, and around 20-25 kt over land. Gusts then decrease around 5 kt or so for the evening.