The Washington Post

Behind today’s busted forecast: the wedge always wins

Temperatures at about 5,000 feet (or 850 mb) this afternoon are around 12-15 C, which - ordinarily - translates to temperatures near the ground in the 70s F (at least mid-20s c) *if* there is sunshine (and not a cold layer of air near the ground). (

We won’t get out of the 50s today and we may not go above 55 in the immediate D.C. area. Meanwhile in Staunton, Va. it’s 70. So cruel.

The warm air at higher altitudes coming over top of the cool air at the ground caused the thick blanket of fog. (This is known as advection fog - we wrote about this last month under similar circumstances ). The graphic above shows the orientation of the wedge as marked by the warm front in west central Va. cutting southeast towards Virginia Beach. South of the wedge, temperatures rise into the 70s. To the north, it’s mainly in the 50s and foggy - as illustrated by conditions in the District this afternoon.

This wedge was caused by high pressure off the coast of New England, the circulation around which delivered this clammy air. Even though this marine weather system is not particularly impressive or strong, it’s proven to be enough to spoil what appeared to be a promising January thaw.

Jason is the Washington Post’s weather editor and Capital Weather Gang's chief meteorologist. He earned a master's degree in atmospheric science, and spent 10 years as a climate change science analyst for the U.S. government. He holds the Digital Seal of Approval from the National Weather Association.

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