Posted by Chris Lambert
A few things are coming together to provide us tropical downpours at times through Wednesday.
An onshore flow coming in from the mid-Atlantic has brought in plenty of moisture across that area the last couple of days. That's moving north. Also the moisture of what's left of Isaac (remnants), is sliding in from the Ohio Valley. Plus, there's a cool front in the Midwest that's moving east, which is helping pull all that moisture north.
So what to expect today? Not everything comes together today, but enough moisture streaming in from our south is enough to provide scattered showers... scattered being the word to focus on. There will be dry times as well today between passing showers so my best advice is to keep the umbrella handy, but know there will be times you wont need it.
Tonight... showers become more numerous, especially northwest of Boston and since the atmosphere is loaded with water vapor, we'll have plenty of moisture to wring out tropical downpours. All of us have the chance for heavy rain after midnight tonight, and through the first half of tomorrow. Many locations pick up 1-3" of water, with locally more in a few towns possible. The rain will be enough to produce localized flooding on the roadways and poor drainage areas tomorrow, but larger streams and rivers should be able to handle the water just fine. No flood watches or warnings are up as of 7AM today... but I wouldn't be surprised to see a few flood advisories or an isolated flood warning pop up once the heaviest rain fills in overnight/tomorrow. At least the lawns will appreciate this one.
After tomorrow, the weather is generally quiet, with just a small chance of a shower/storm Thursday and Saturday.
One big thing we do have to watch for next weekend and early next week is the evolution of what becomes Hurricane Leslie. Right now, the best estimate of Leslie's track would be a few hundred miles east of us. Obviously the track of a hurricane 7 days out can be challenging, so that's certainly a close enough pass where we need to watch it. Even at this track, we'll feel some impacts. The main impact being rough surf, large seas, likely rip currents and possible beach erosion. The height of that concern is Sunday-Tuesday, but we'll have the seas build offshore well before that.