The video footage above (YouTube) was filmed in Ohio during the infamous June 29, 2012 derecho that impacted the Washington Region during the evening hours.
Several Mesoscale Convective Systems (MCS) will likely impact the Washington Region this afternoon.
I am currently watching one MCS over Ohio that is moving fairly quickly toward the east-south-east which may impact the D.C. Region between 3 and 7PM, according to the latest high-resolution models.
Damaging straight-line winds in excess of 70 mph are possible with this line of thunderstorms as it races through the DC Region later this afternoon. These storms will have the potential to knock out power to thousands, snap trees and bring down power lines. Please pay close attention to the National Weather Service as the Storm Prediction Center may issue Severe Thunderstorm Watches across the Washington Area this afternoon.
For those of you across central Virginia, lower-southern Maryland, north-central Virginia and the Northern Neck of Virginia, a second MCS may impact your area later on this evening between 7PM and 11PM.
Now would be a good time to secure loose objects in your yard, stacking chairs, patio furniture in case Severe Thunderstorm Warnings are issued for your location.
- Lapse rates are a bit steeper this afternoon so these storms will also pose a threat of hail. The tornado threat today is low but not zero as wind shear values are not strong enough for a widespread tornado threat (shear values will increase on Sunday evening as an upper-level trough approaches).
- Keep a close eye to your favorite local media outlet & the National Weather Service. Be prepared to find a safe place in your home away from windows in the lowest level and for those of you who live in a very wooded area, please have a plan to protect yourself in case trees do come down.
- Most of us remember the Derecho that impacted the DC Area in 2012. The Washington Area is on the northern periphery of an upper-level high pressure system today. The jet stream will be roaring overhead later this afternoon and the contrast between the high heat and humidity and the relatively cooler air just to our north will provide the necessary ingredients for these large thunderstorm complexes to strengthen during peak daytime heating as they cross our region this afternoon.