Shower activity has been occurring during the overnight hours as moisture presses northward along areas east of the Appalachians. There has also been patchy fog, which has reduced the visibility to less than a mile in some places. We’ve still got a very unsettled weather pattern to contend with here over the next few days, and the consensus still is that the most widespread and heaviest rain across the Greater Baltimore Area will occur from late tonight into tomorrow. While an additional 0.10-0.25″ of rain is likely today (although a stray thunderstorm may yield somewhat higher amounts), all of the models are still suggesting that a general 1-3 inches of rain will soak the region late tonight, tomorrow and early tomorrow night.
As the latest cool front limps into the Eastern Region today, it then will be destined to slow down even more when it reaches eastern Pennsylvania and upstate New York tonight. Then, as an upper-level low pressure system establishes itself in the Ohio Valley and southeastern Great Lakes tomorrow and tomorrow night, a fairly healthy-looking wave of low pressure on the surface weather map that develops along this old front will be lifting northward tomorrow afternoon and night. Those places, which were the hardest hit by “Lee’s” moisture about two weeks ago, mostly along the Susquehanna River Basin in eastern Pennsylvania, will probably not see the heaviest rain this time around. However, that general 1-3 inches which we’re calling for along the I-95 corridor will probably be enough to generate some nuisance flooding on a few streets and highways, as well as in areas of poor-drainage. The tendency for that wave of low pressure to start lifting out to the north tomorrow night should allow for the most persistent rain to end by around midnight, but that does not mean we’re expecting any push of drier air to take place in time for the start of the upcoming weekend.
Even though it appears at this point that the weekend won’t bring us the same kind of rainfall totals that we’re anticipating tomorrow, it’ll still be a good idea to keep the umbrella and the rest of your rain gear handy.