A very warm and more humid day is in store for most of the Eastern Region this Friday as high pressure currently located near the coast continues to glide slowly out into the Atlantic. But, most locations will have a good deal of sunshine with temperatures poised to soar into the mid and upper 80s this afternoon. Some local thermometers, especially south of the Mason-Dixon Line, will wind up near or slightly above 90.
While a couple of spots will get a brief shower or thunderstorm before the day is over, or even early Friday night — it is more obvious that we’ll be seeing a greater distribution of showers and thunderstorms occurring here from Saturday afternoon into Saturday night. In the short term, it is prudent to allow for something both later Friday and early Friday night, and then watch the radars closely as the situation warrants. A strong cold front will generate showers and thunderstorms in areas surrounding the Great Lakes on Friday, and then across the Ohio Valley Friday night and early Saturday morning.
As this front presses eastward Saturday, dewpoint temperatures in areas along the coastal plain are expected to surge into the upper 60s and lower 70s ahead of the boundary. Daytime temperatures along the I-95 corridor will peak in the upper 80s or lower 90s before some showers and a drenching thunderstorm roll in. Most of the rain will occur after 2 p.m. and before 10 p.m. or 11 p.m. — except perhaps in extreme South Jersey and the Delmarva Peninsula, where the front and its convection could linger into the overnight hours.
The rainfall we’re expecting should average 0.25 – 0.50″, although some places that encounter a drenching downpour could get over an inch. Perceptible water values, or a model’s interpretation of how much rain could fall based on mathematics (output based on an integrated vertical column of air) would suggest some of the absolute highest totals would be between 1.5″ and 2.0.” Wind shear, or winds that change direction rapidly with increasing height, doesn’t appear as if it will be a key player, so thunderstorms will probably only produce wind gusts of 40 or 45 mph, at the very most. As this front finally manages to press to the south and east of the area on Sunday morning, any residual clouds will manage to break for some sunshine. And, in addition to being noticeably cooler, it will also become much less humid.
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