Comment Hundreds of trees were downed and hundreds of thousands of people lost power Tuesday afternoon and evening as three clusters of storms roared through the Washington area. The storms were fueled by warm and moist air moving over the region and were fueled and sustained by strong high-altitude winds along an approaching cold front. Two bands in particular are responsible for the lion’s share of the damage. They were both arched arc-shaped lines that swept from west to east. The first plowed from Washington County to Cecil County in northern Maryland in the late afternoon. The second hit Northern Virginia, the District and central Maryland during the evening. Both brought down dozens of trees and power lines – some to homes and cars. The DC area is being cleaned up after a severe storm A third, somewhat less intense cluster was spotted over north central Virginia and southern Maryland late in the evening, leaving behind scattered reports of damaging winds and at least one case of flash flooding. In total, the National Weather Service received about 150 reports of damage from the three complexes. Pockets of hail also formed within the storms, some as large as half dollars. PowerOutage.US reported that more than 70,000 outages still remained Wednesday afternoon, nearly 24 hours after the storm — the majority in northern Maryland. All three bands produced downward bursts of violent winds that fell to the ground and spread outward. The National Weather Service received about 40 reports of winds between 39 and 70 mph. Here are some of the top gusts recorded:
Centerville: 70 mph Leesburg: 62 mph Washington Dulles International Airport: 60 mph Quantico: 59 mph Reagan National Airport: 52 mph
Within a one-county radius of Washington, concentrated damage was reported near Chantilly, Olney, College Park and Bowie. Olney appeared to be hardest hit, where trees damaged up to 20 homes and displaced about half a dozen families. Damage was also extensive in College Park, where a man was seriously injured when a tree fell on a house. The Weather Service concluded that peak winds in the area reached 80 to 90 mph and that the winds were blowing in a straight line, ruling out a tornado. 608p: Radar shows very strong winds just east of College Park towards the Greenbelt…probably headed for Glenn Dale. Take shelter in this area, possible microburst with winds 60-70 plus mph. pic.twitter.com/2rddBQMpxr — Capital Weather Gang (@capitalweather) July 12, 2022 “Straight-line winds from storms can cause tornado-like damage,” the Weather Service wrote in a storm survey. “Yesterday afternoon’s estimated winds in College Park are equivalent to those of a low-level EF1 tornado.” The stunning sunset features red skies, lightning and rainbows — all at the same time The storm that caused the severe wind damage in Olney and College Park is known as a long-haul bow echo. A bow echo, unlike a supercell which is organized around a rotating updraft, is activated by a strong downdraft. The surge of strong downwind causes the front of the storm line to roll outward, racing ahead of neighboring areas. Bow echoes often travel at high speeds of at least 40 to 50 mph. 556p: Heavy storm from Olney to Arlington to Burke. College Park, Capitol Hill, Old Town, Fort Washington, you’re next. Strong winds, hail, lightning and flooding on the way. pic.twitter.com/ynqOH8bPla — Capital Weather Gang (@capitalweather) July 12, 2022 The radar image below shows the bow started over West Virginia, south of Romney, between 3 and 4 p.m., as tracked by the National Weather Service’s Storm Prediction Center. The National Weather Service office in Sterling, Va., has issued an ongoing series of severe thunderstorm warnings ahead of this storm up the Chesapeake Bay. The next figure shows the storm at 5:30 PM as it approached Interstate 95. The arc shape is unmistakable. The northern end of the bow echo had developed into a comma-like structure and may have contained a large vortex, as is common in this type of storm. The strong downdraft along the leading edge of the storm created an ominous cloud – where moist air rises a few hundred feet and then condenses into a low cloud. This north party head produced a strong downdraft that impacted the subdivision just south of downtown Olney at 6 p.m. An enlargement of the cell is shown in the next figure. The heavy rain echo mass at the northern end of the bow is shown in the left panel. The right panel is Doppler velocity and reveals air currents hidden in the rain. The white circle encloses the area affected by the blast, but the most extreme winds were confined to the pink sub-region, just southwest of Olney. This is a strong flow away from the radar, to the northeast. The green adjacent area represents strong flow to the southwest. Taken together, these two patches indicate strongly divergent airflow. The assumption here is that an intense downdraft core hit the surface at an impact point shown by the white “X”. The white arrows show the bidirectional outflow from the impact point. Winds in the pink area must have generated winds of at least 60 mph, possibly stronger given the size of the trees that were downed. Many people hear a sudden roar as the wind rapidly accelerates to high speeds during a downburst. After the storm, the extent of tree damage can seem incredible. Based on the level of damage and the roar, many assumed a tornado had occurred. But similar to the situation in College Park, the radar shows a divergent, rectilinear wind pattern, rather than the rotating signature that would be associated with a tornado. As the bow echo approached, the ominous shelf cloud was a sight to behold. We received dozens of cloud photos from readers and are sharing a sample below:
