A quick look at the radar this morning tells you all you need to know… expect a good deal of shower activity today with scattered thunderstorms and little in the way of sustained sunshine. A warm front across central Pennsylvania will crawl eastward today before being overtaken by a cold front currently in Ohio. The combination of deep moisture and frontal lifting will yield torrential rainfall in some of the heavier storms, and it’s still not out of the question for a few gusty thunderstorms as well this afternoon, but with less sunshine than previously expected the potential for severe weather is fairly marginal. This could change if we’re wrong and more sunshine is had. We may see a break in the action later this morning before storms move back in early in the afternoon
The cold front will advance eastward and off the coast late tonight, so after a fairly wet evening things should begin to clear out at least a little for the 4th with more sunshine returning. It will be several degrees warmer behind the front owing to sunshine and better mixing, but fortunately dew points till drop off by several degrees making the holiday pretty decent — especially when compared to last year when it ended up 96 and humid! We will run the risk of a breif shower or
thunderstorm, however, in association with a weak upper-level disturbance moving through the region. Rainfall chances are pretty low (10-20%), but considering that it’s a holiday in which plenty of people are outdoors it may be worth keeping in the forecast. By far best chances exist to the south of the DC area… (30% or greater here).
The flow becomes southwesterly on Tuesday and keeps a warm air mass over the region, but given that the upper-level pattern will continue to feature a very broad trough over the Northeast it will not be “hot.” The next decent shot at rainfall looks to be Wednesday night into Thursday as another cold front moves into the Mid-Atlantic region. Expect humidity to surge as well with the end of the week looking quite muggy. The pattern is shaping up to be an active one in the long range…