WEATHER BLOG: Not A Washout Weekend
A front is slicing west to east across the area right now so a cooler, drier NW flow is sweeping across the area and some lingering clouds will eventually give way to a good deal of sunshine later Friday in the wake of the cold front.
Surface high pressure off to the west will control the weather later Friday behind the cool front and with strong sunshine and well-aligned winds, we mix down from above 850mb to the surface later Friday. With winds at 850mb around 30-35 knots, that should translate to wind gusts in the 30-40 mph range throughout the day as sunshine allows those stronger winds aloft to be translated down to the surface.
Cold advection aloft will continue throughout the day Friday and with the cooler air aloft/upper trough, a stray shower or sprinkle in the high ground of western Maryland cannot be ruled out. But in the city we should have too much down sloping, and forecast soundings show plenty of dry air on the down sloping northwest flow so we should have a good deal of sunshine despite the cool, gusty winds.
Friday afternoon supports highs a bit lower than 62. We elected to keep continuity and keep the high around 60 Friday afternoon.
On a bright sunny day in late April, we will be hard pressed to be more than 7 degrees below normal– we think.
Winds settle down some Friday night as we lose heating of the day/mixing and the gradient weakens as high pressure builds eastward. Areas outside the towns and cities may see a frost or even a hard freeze with clear skies, lighter winds and a fresh cool air mass building in.
The surface high retreats Saturday, so although we should start the day bright and sunny, mid and high level clouds increase in the afternoon as a wave of low pressure skirts by to our south along the frontal boundary late Saturday and Saturday night, bringing a period of rain to the area Saturday afternoon into Saturday night, with average rainfall amounts probably 1/4 to 1/2 of an inch.