Last night and this morning's fail in the computer models was due in fair part by some dry air that had nudged into the Delaware Valley and helped to shove the rain shield off the coast by about 50 miles. The weak surface high that had brought a relatively "cool" day to the region on Sunday (high of 80) had just enough of a grip on our weather to block a closer to the coast approach by low pressure that pushed off the coast overnight. The only model to hint at this solution was the GFS -- and it handled it rather well.
Today's forecast is a bit "easier" and there's more agreement in the models about scattered showers and storms developing this afternoon as a weak disturbance pushes east into Pennsylvania over the next several hours. Scattered showers and storms will be around, more numerous in Pennsylvania than in Delaware or New Jersey, through the duration of the day.
The NAM (above) and GFS (below) both show the potential at least some scattered shower activity around after 2 PM. A few of these could sneak into the Philadelphia metro after 5 PM but modeling suggests most of these track northeast and track from Central into Northeastern Pennsylvania. A better chance of showers would exist in the Poconos and out to our west than locally.
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