Low pressure will travel quickly from northern Arkansas to western Pennsylvania by later this evening and it will then trek across Pennsylvania early tomorrow. This storm track will first send a warm front through the region this evening and that will then be followed by a strong cold frontal passage early Wednesday. As a result, the next several hours will continue to see a steady, soaking rain, but then the precipitation pattern will evolve into more of a shower/thunderstorm type of pattern from late tonight into tomorrow morning and some of the storms that form can produce heavy rainfall. Also, there is a good chance for some thick fog to develop late tonight and early tomorrow as temperatures actually rise overnight from the current readings in the upper 40’s to near or slightly above 60 degrees by midday on Wednesday. Widespread rainfall amounts from this storm will be in the 1-3 inch range throughout the Mid-Atlantic between now and midday on Wednesday so flash flooding is a concern. Clearing skies then set in for the holiday on Thursday, and it should stay dry on Friday and Saturday as well.