Rainfall last night was sporadic in spots -- Philadelphia picked up just 0.12" through 5 AM -- but for others was plentiful (see Pottstown's inch plus total). The region is picking up some needed rainfall in today's storm system -- some locations could see over two inches by the time everything winds down later tonight. Additionally, the cooling relief of east winds off of the Atlantic, while adding more "fuel" to the drenching showers, is definitely a nice change of pace from a scorching sun and 100 degree temperatures.
The key to today's rainfall, as we hinted in our daycast this morning, is that it's not a widespread soaking. Since today's rains are of the showery variety and not a solid band of widespread rainfall, some locations will pick up more rain than others. One of the higher resolution versions of the NAM (below) shows the potential for over two inches of rain in spots around the Delaware Valley today. The Euro shows similar potential -- although places the axis of heaviest rainfall potential north of the city (where showers will be more consistent and persistent today).
Places that do see more consistent and persistent shower activity will get upwards of two inches of rain before all is said and done today...and there will be places that end up with just a quarter inch of rainfall while others 20 miles down the road soak to those aforementioned two inch totals. A flash flood watch is out in Central Pennsylvania but not out as of the time of this post locally. While most of the region should get at least some badly needed rain some of it will be of the "too much, too fast" variety...resulting in localized ponding of roadways and areas that don't typically drain well. Even though there isn't a flood watch out locally some of the more susceptible and traditional spots to get a minor flood or ponding situation could see that happen today.
Rains should gradually taper off this evening and tonight as the mid level system pulls off the coast. Thunderstorms may develop south of the city later today, some of which will be locally strong or severe, and bring additional rains to places where they develop.
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