New month, same story!
What a sloppy atmosphere we're dealing with this holiday weekend! With plenty of heat and humidity, it doesn't take too much to spark storms. And a weak surface boundary stalled out across New England will help to produce scattered rain throughout the course of Sunday.
So far as rain chances go, they'll be lower across northern New England than they will across Southern New England. It's SNE where the air is juiciest and most unstable, with dew points near 70 and highs into the low 80s. In fact, that air is so warm a few thousand feet above us (at 850mb) that if we could manage full sun, temperatures would spike well into the 90s. That being said, there will be too many clouds around to let that happen. Much like yesterday it won't be a washout, but there will be rain to dodge from time to time. And with so much water vapor in the atmosphere, heavy downpours will be possible with isolated areas of flash flooding.
The storm in Needham/Natick/Wellesely this morning is a good example. Torrential rain can add up to 3" in an hour! PWAT (precipitable water) values are extremely high today, near or above 2", which means there's plenty of water in the air above your head! Street flooding can make road impassable, and vivid lightning can be expected too. That is the main threat today. Again, most of the heavy rain potential should be south of Route 2 today south of a stationary front.
The only thing that changes for tomorrow is that the trough to our west deepens, a cold front starts to move in, and showers and storms will become even more numerous/widespread. Otherwise it's status quo, with warm and very humid air in place. That same front will take its sweet time trying to move through, which will keep quite a few clouds and some showers around on Tuesday. But by Tuesday night, we should finally be able to wave goodbye to a very unsettled pattern.
Wednesday is looking delightful at the moment, with a nice north-westerly breeze and highs near 80. A trailing cold front should sweep through again on Thursday, but this one will have a good head of steam going. It may bring a brief afternoon shower, but otherwise will just deliver a nice seasonable air mass for Friday.
Have a great holiday weekend,
E
