A low pressure system, now located in eastern Canada, has been dragging a cool front across interior parts of the Northeast and mid-Atlantic states during the night. That front will be pulling away from the coast early today. This will be an honest to goodness “cool front” for many folks in the Eastern Region. But for others, especially in southeastern New England and on Long Island, it’ll just be a trough of low pressure that will cause a wind shift. In fact, since temperatures were no higher than the lower 50s yesterday across coastal Connecticut, today should actually turn out to be a little milder with a westerly component to the surface wind and the sun managing to come out.
Yesterday, a warm sector managed to get pinched off over central and southern New Jersey, as well as southeastern Pennsylvania, Delaware and Maryland. While it reached 86 degrees at BWI and 88 at the Maryland Science Center, most communities about 150 miles to the north and east were no higher than the upper 60s and lower 70s. And, as we highlighted earlier, many south-facing shores were no higher than the 50s. Today, the marine influence will be wiped out by the prevailing offshore winds, which could gust as high as 30 mph. Under a mostly clear sky tonight, those winds should diminish rather quickly, and most temperatures will drop into the 30s and lower 40s. The coldest spots well inland from the coastal plain may even be near or slightly below the freezing mark at daybreak tomorrow. A wedge of high pressure building down from the Great Lakes and interior parts of the Northeast will keep the weather dry across much of the region tomorrow, although any morning sun will tend to fade behind increasing clouds. And, with a colder start to the day (compared to today), most afternoon temperatures will be hard-pressed to get out of the lower-50s.
A warm front tomorrow is going to be pressing northeastward through the Ohio Valley and into the mid-Atlantic states. Therefore, some steady precipitation spreading out across the central Appalachians during the morning should start to advance eastward during the afternoon. Our current thinking is that it’ll start to rain (albeit lightly) across most of eastern Pennsylvania late tomorrow afternoon, and then New Jersey, much of southeastern New York and southern New England will see it start to rain tomorrow night (earliest in western zones, but later in eastern areas). That rain tomorrow night should taper to a few showers by early on Saturday.