The Storm Prediction Center has placed the Washington DC Region under either a “slight” (yellow area in below image) or “enhanced” (orange area in below image) risk for severe thunderstorms this afternoon. A warm front will be advancing northward through the Mid-Atlantic while a cold front moves southeastward out of Pennsylvania.
Severe Thunderstorm Risk Categories Explained
Wind Shear and Tornadoes
Wind shear is defined as winds that change in direction and speed as you move higher in the atmosphere. Wind shear values will increase between 40 and 45 knots this afternoon, aiding in some storms to become rotating super cells. The main threat with today’s storms will be damaging winds in excess of 60mph and large (1 to 2″ diameter) hail. Additionally a few storms may spawn a few tornadoes.
Timing Today’s Severe Thunderstorms
The latest high-resolution models indicate storms will likely fire anytime today after 2 or 3pm and advance into the immediate metro area just in time for rush hour (4 to 6pm).