textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes to the forecast.

KEY MESSAGES

- Quiet and dry stretch of weather today through the end of the work week.

- Potentially unsettled and cooler conditions this weekend into early next week.

DISCUSSION

KEY MESSAGE 1...Quiet and dry stretch of weather today through the end of the work week.

Fairly high confidence in dry weather this week as surface high pressure and mid-level ridging develop across the Northeast. Right on cue following a cool and damp weekend, warmer and drier weather returns to southern New England. There have not been any wholesale changes to the forecast, as we continue to anticipate a period of dry and warmer weather today through the end of the work week.

Today, the mid-level trough and shortwave push east. While PWATs are quite low, the combination of modest mid-level lift, a cold pool aloft, and a few hundred J/kg of CAPE suggests a brief and very isolated pop-up shower cannot be ruled out. Otherwise, expect diurnal cloud development this afternoon due to daytime heating and deep boundary layer mixing. With 850 mb temperatures around +8C, highs should reach the lower to middle 70s.

Mid-level ridging and surface high pressure develop Wednesday through Friday, with increasing 850 mb temperatures between +13C and +15C Thursday and Friday. While these temperatures alone would support highs in the lower to middle 80s, west-northwest flow aloft descending from the higher terrain of western Massachusetts should promote compressional warming/downsloping. This will likely nudge highs into the upper 80s, perhaps near 90 degrees, especially Friday afternoon across the Connecticut River Valley, where probabilities exceed 75 percent.

KEY MESSAGE 2...Potentially unsettled and cooler conditions this weekend into early next week.

Looking toward the weekend, forecast confidence lowers due to variability among guidance. The broad thinking remains that surface high pressure shifts offshore, mid-level heights fall, and cooler temperatures advect aloft.

As noted by a previous forecaster, there is a chance much of Saturday remains dry. However, there are enough signals to warrant at least a mention of scattered afternoon showers. By Sunday, a low pressure system passing near a nearly stalled frontal boundary presents a more favorable setup for showers. This front could linger into early next week, continuing at least some risk for showers.

This will clearly be something to watch, as we appear to remain in an unfortunate pattern of cooler and soggier weekends across the Northeast. Temperatures should begin trending cooler Saturday, though the cooldown is expected to become more noticeable Sunday into early next week.

AVIATION /12Z TUESDAY THROUGH SATURDAY/

Forecaster Confidence Levels...

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

12z TAF Update:

Today through Wednesday...High confidence.

VFR. A low chance for a brief (less than 20 percent), isolated shower mainly between 19z-01z, otherwise, dry conditions today through Wednesday. Winds today are from the northwest at 8 to 12 knots for interior locations, while coastal sites experience an onshore wind from the south to southeast. Overnight, light to calm winds prevail, followed by light northwest winds across interior locations as high pressure settles into the region on Wednesday. Coastal locations will have a light onshore wind.

KBOS...High confidence in TAF.

VFR through the TAF period. A sea breeze develops between 15-17z, followed by light winds overnight and then a weak sea breeze on Wednesday.

KBDL...High confidence in TAF.

VFR with northwest winds today and Wednesday, with light to calm winds overnight.

Outlook /Wednesday Night through Saturday/...

Wednesday Night: VFR.

Thursday: VFR. Breezy.

Thursday Night: VFR.

Friday: VFR. Breezy.

Friday Night: VFR.

Saturday: VFR. 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 Wednesday...High confidence.

In general, conditions today through Wednesday will support tranquil boating conditions as surface high pressure remains the dominant feature. Dry weather prevails as well, though there is a very low chance of a pop-up shower mainly this afternoon into the early evening (less than 20 percent), otherwise, dry conditions persist into Wednesday. Winds today are generally from the south to south-southwest at 10 to 15 knots, becoming light and somewhat variable on Wednesday as high pressure settles over the region. However, colder sea surface temperatures relative to warmer land temperatures will promote onshore winds across waters near the immediate coast. Seas generally 2 to 4 feet today, subsiding to 1 to 3 feet on Wednesday.

Outlook /Wednesday Night through Saturday/...

Wednesday Night: Winds less than 25 kt.

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

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

Saturday: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...None.