DAYS 1-5 (JUNE 26-30)
A “quiet” warm front went by overnight. The only evidence you had of it here is the variety of high and mid level clouds that appeared late yesterday and last night, and if watching radar you saw some light showers cross northern New England. This has opened the door for a one-day shot of heat and humidity, though it won’t be nearly as hot as our hot spell of last week, with most areas topping out in the upper 80s to around 90. The exception of course will be the South Coast which will feel a cooling effect from a southwesterly wind coming off the ocean water, which while it has warmed up significantly since spring, is still a couple months from reaching its summer peak. There will be a South Coast sea breeze boundary which can help trigger a few showers and even a thunderstorm this afternoon in an east-west orientation – best guess in the vicinity of I-90 but may be a bit south or even a bit north of there, so watch for developing clouds and you can get a visual clue as to what’s happening before anything forms. Much of the rest of the region will remain rain-free through the daylight hours. It’s later this evening and overnight when a more widespread batch of showers and embedded thunderstorms will move through the region as the cold front moves into and passes through the region. While these showers can linger over eastern areas into early Thursday morning, the bulk of Thursday is going to feature a return to sun, with passing clouds, and lowering humidity, cooler compared to today but still pleasantly warm in the afternoon without the higher dew point air. There is one more trough that has to swing through the region late in the day that can trigger a couple showers and a thunderstorm, but these should be generally isolated to widely scattered and quick-passing if/where they do occur. A fresh Canadian air mass settles in for Thursday night and Friday with low dew points, a cool nighttime and a pleasant daytime. A northwesterly air flow should keep up well into Friday which should prevent sea breezes, but the air will be refreshing anyway, along with plenty of sun to be enjoyed. The weekend will feature some weather changes. High pressure will slide offshore Saturday and a warm front will approach, bringing an increase in clouds. This front may bring some shower activity but right now I feel the bulk of that will occur west and north of Boston later in the day. It’s then overnight and Sunday morning that a cold front will approach and move through with the most widespread shower and potential thunderstorm activity, with a follow-up trough maybe popping a shower or storm in some areas Sunday afternoon before we clear out again. Humidity levels will come up again Saturday into Sunday, but without high heat, and the humidity will then break again later Sunday.
TODAY: Sun/cloud mix. A few showers and possible thunderstorms favoring the I-90 belt mid to late afternoon. Highs 77-84 South Coast region, coolest immediate shoreline, 85-92 elsewhere. DP rises to middle 60s to around 70, highest South Coast. Wind SW 5-15 MPH, a few higher gusts.
TONIGHT: Mostly cloudy. A few showers possible early, then more widespread showers with embedded thunderstorms late evening and overnight. Patchy fog forms. Lows 65-72. DP 60+. Wind SW 5-15 MPH.
THURSDAY: Mostly cloudy with a chance of showers and thunderstorms in the early morning. Partly sunny mid morning on. One more possible shower or thunderstorm mid afternoon to early evening northwest to southeast. Highs 80-87. DP falls below 60 by late-day. Wind W 5-15 MPH shifting to NW late.
THURSDAY NIGHT: Clear. Lows 55-62. DP falls to lower 50s. Wind NW 5-15 MPH.
FRIDAY: Sunny. Highs 75-82. DP lower 50s. Wind NW-N 5-15 MPH.
FRIDAY NIGHT: Clear. Lows 55-62. DP lower 50s. Wind variable under 10 MPH.
SATURDAY: Sunny start, then variably cloudy. Mid afternoon to evening rain showers and a slight chance of thunderstorms favoring central MA and southern NH. Highs 73-80 South Coast, 80-87 elsewhere. DP rises back over 60. Wind S 5-15 MPH.
SATURDAY NIGHT: Mostly cloudy. Showers and possible thunderstorms become more likely from west to east late evening and overnight. Areas of fog overnight. Lows 63-70. DP 60s. Wind SW 5-15 MPH.
SUNDAY: Variably cloudy. Showers most likely in the early to mid morning. An additional shower or thunderstorm possible in the afternoon. Highs 78-85. DP 60+ much of day, lowering late. Wind SW 5-15 MPH, shifting to NW late.
DAYS 6-10 (JULY 1-5)
During this holiday period we’ll see a west to northwest air flow and progressive pattern. A couple disturbances / fronts bring passing shower and t-storm chances, but it’s hard to time these this far in advance. The bulk of the period sees rain-free weather. Temperatures start out coolest, then warm to a little above normal.
DAYS 11-15 (JULY 6-10)
A similar pattern to the previous period. More detail to come…