The National Weather Service's Storm Prediction Center has issued a forecast calling for the potential of severe storms today in Philadelphia, Baltimore, and Washington. These cities are in the "slight" risk category, which means that any severe storms that develop will not be widespread. In fact, the Storm Prediction Center believes that there is only a 15% chance of "severe wind" and only a 2% chance of a tornado. Nonetheless, gusts of 30 or 40 miles per hour are not out of the question in some thunderstorms.
A cold front attached to a strong area of low pressure will sweep across the Middle Atlantic states today and tonight. Warm, moist, unstable air ahead of the front will cause the air to become unstable when the colder, drier air behind the front clashes with the air mass already in place over the region. Convective development will produce widespread showers with isolated thunderstorms. As indicated above, isolated storms may reach the severe stage. Tornadoes are not expected, but a tornado watch may need to be issued depending on the ultimate development of these conditions during the day. Some showers may be briefly heavy with localized flooding, although most areas will only see light to moderate showers.
By later this evening, the cold front will progress eastward and the chance of severe weather will decrease dramatically. The air behind the front will be significantly colder with temperatures dropping from the 60s and 70s on Wednesday afternoon into the 20s and 30s by Thursday morning. Highs on Thursday will only reach the 30s on Thursday and Friday. The average high for this time of year is in in the upper 40s around Philadelphia to the lower 50s in Washington DC.
Here are forecasts for specific locations around the Middle Atlantic states:
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