After yesterday’s highs in the lower 90s, an intrusion of drier air leaked southward into northern MA last night into this morning. The dewpoints dropped 5-10 degrees which was enough to make a noticeable difference. Unfortunately, that was temporary as the humidity ramps up again today. Is there any real relief in sight? There is a chance that some slightly less humid air will return on Tuesday and Tuesday night following an upper level disturbance which will trigger more widespread showers and storms here tomorrow. This will also be a temporary situation because it will become more humid again Wednesday and Thursday ahead of an approaching cold front which will trigger another round of showers and storms across much of the area during Thursday. Behind this frontal boundary is a nice mass of refreshing dry air associated with a high pressure system crossing the Great Lakes later Thursday and Friday. Extrapolation would support advancing this genuine relief into New England later Friday and next weekend. However, it is July and it appears that the frontal boundary is going to run into stiff resistance as attempts to push offshore. Presently, it appears that it will stall out just offshore as the big high pressure system over the Atlantic restrengthens and reconfigures. This new setup is destined to steer moist air in from the ocean and override the boundary which will slowly shift northwestward into southern New England. Consequently, unsettled, showery and perhaps foggy weather may materialize next weekend. So, although it will turn drier Friday especially north and west of Boston, it looks like the humid air will retreat into the region next weekend.
Back to the more immediate future with today, the threat of showers and storms increases somewhat over the past few days. Over southeastern MA and especially Cape Cod, that threat is very minimal while north and west of the city, its will shoot up. One weakening batch of showers and storms will probably mostly dry up as it pushes into western NH this morning. Its cloud debris will spill over mainly northern MA with a period of cloudiness into midday followed by some sunnier weather this afternoon leading to developing and building clouds for more showers and storms scattered around later this afternoon and early evening. It will still be hot today and with the high to oppressive humidity, another Heat Advisory has been issued by the National Weather Service for parts of the area running from 2 pm to 7 pm. Nevertheless, expect temperatures again cracking 90 degrees making this day 5 of the heat wave. Boston’s projected max of 93 is short of the record of 99 set in 1993. There will not be any decent ventilating wind either as it blows from the west-southwest at 5-15 mph. There is just a low chance that a switch to a feeble sea breeze happens at some beaches with the tide on its way out to be low just after 5:30 pm.
Joe Joyce post the next blog early this evening and I shall return early tomorrow morning.
Enjoy the rest of the holiday weekend!