The relentless parade of stalling cold fronts over the Mid-Atlantic will bring more rain to the region this weekend. The weekend will be cool but pleasant for most of the Northeast, but in the vicinity of the stalled cold front, heavy downpours will mark another rainy Saturday.
Summer-like weather will briefly grace the Mid-Atlantic and much of southern New England Friday, with temperatures reaching the upper 70s to mid 80s. This pleasant weather will be erased by surface high pressure over Ontario, which will send a southeastward moving cold front into the Northeast Friday night into Saturday, bringing showers and thunderstorms along with it. Between Friday night and Saturday, the cold front will stall somewhere between northern Virginia and southern New Jersey as previous storms have done. Passing shortwaves will spawn kinks in the front, resulting in the formation of a weak cyclone that will intensify showers and thunderstorms that develop along the front.
The greater Washington, D.C. area has undergone scores of torrential downpours in recent weeks, which ultimately resulted in the devastating flooding of Ellicott City, Maryland two weeks ago. If the cold front stalls over the region flooding woes will resume. Fortunately, the front is currently expected to stall closer to Philadelphia, meaning the heaviest rain should be focused south of I-76 over Pennsylvania, New Jersey, and Delaware. Fewer showers will develop over the Hudson Valley, New York City, Long Island, and southern New England. Ultimately however, the D.C. area will likely be unable to completely escape the heavy rainfall threat, with the front resuming southward Sunday.
Temperatures will be about seasonal along and in the vicinity of the stalled front, with high temperatures in the upper 70s. Saturday will be much cooler than normal over most of New York and New England, with temperatures in the low 60s to around 70. Despite this cool weather, these areas will remain dry throughout the weekend.
As low pressure clears the coast Sunday, the cold front will shift southward. Skies will begin to clear in southeastern New York and the northern two-thirds of New Jersey and Pennsylvania, but temperatures will be stuck in the 60s to near 70. As the front progresses southward, it will return heavy rain chances to Maryland, Delaware, and northern Virginia, which have only just begun to dry out from the last few weeks of flooding rains.
There is a great deal of uncertainty regarding the southward progression of the front, with numerical weather prediction varying in its speed and location. The GFS depicts the front clearing the area by Sunday night, stalling near Virginia Beach. Hopefully this turns out to be the case, since the Euro and various members of the GFS and ECMWF ensembles keep the Washington area wet through early next week. If this were true, widespread flooding will resume for areas already inundated over the last few weeks.
This situation will need to be monitored closely and WeatherOptics will provide updates as the uncertainty clears.