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On Wednesday afternoon, two strong thunderstorms hit areas south of Washington; the cities of Fredericksburg and Warrenton were particularly hard hit. While the immediate area of DC was spared these initial blows, it was soaked by a relentless stream of turbulent cells on Wednesday night. This “rain train” caused areas of flooding and puzzled storm watchers by its unusual north-south movement.
Storms in Fredericksburg and Warrenton – with expected winds above 80 mph – felled hundreds of trees and caused more than 100,000 power outages.
Storm Fredericksburg first developed north of the county before breaking out in Prince William County, where it first caused wind damage. The storm then headed south on Interstate 95, knocking down trees and wires all the way, ending south of Richmond. According to reports from the National Weather Service, the winds were strong enough to knock siding off homes and even displace a canopy from its base.
It was the super-intense storm that had hit Fredericksburg earlier with strong gusts of wind. Fast forward to about 25 seconds. https://t.co/zzIzt9xbx9
– Capital Weather Gang (@capitalweather) June 22, 2022
The storm in Warrenton was relatively intense. It initially caused damage to trees in the southern counties of Loudoun and the northern counties of Fauquier around Middleberg and the plains. He felled “dozens of trees” near Marshall, according to the meteorological service. In the west-central county of Foquier, including Warrenton, there were “hundreds of downed trees, many in homes with at least three structures collapses,” the meteorological service said. The storm also felled trees around Culpepper before the storm subsided.
Amid numerous storms in the region, there have been several reports of homes struck by lightning. At least one firefighter was injured in a lightning strike at a home in Ludun County.
The DC region is waking up from downed trees, power outages and some floods
The storms lined up from north to south like trains on a railroad track, unloading heavy rainfall in some areas.
Some of the heaviest rains focused along and just west of Interstate 81, where streams overflowed and roads were closed.
Around Washington, a drill cage train that stretched all the way north to central Pennsylvania passed through the area, beginning at about 7:30 p.m., and continuing well after midnight. Mild floods were reported along Rock Creek at Cheryl and Beach shops, where several vehicles were blocked or disabled.
Usually one to two inches of rain fell in the Beltway area; in the wider region, the amounts range from about 0.1 to over 3 inches. Here are some of the totals:
- Woodbridge: 3.1 inches
- Front royal: 2.5 inches
- Fairfax: 2.29 inches
- Fort Belvoir: 2.18 inches
- Reagan National Airport: 1.86 inches
- Rockville: 1.78 inches
- Winchester: 1.4 inches
- Dulles: 1.00 inches
- BWI Marshall: 0.66 inches
Explanation of the storm
The storms in Fredericksburg and Warrenton were isolated and occurred approximately one hour and 40 miles apart. The systems were compact, arc-shaped complexes of thunderstorms that traveled rapidly from north to south – an atypical movement for our region in the summer.
The storms began and traced along a north-south oriented frontier and were driven by a deep wind from the north.
The first complex froze near Dale City at about 2:15 p.m. and was traced south on I-95 before dispersing south of Richmond. The radar animation of the system is shown below. In the animation, the left panel shows radar reflection (rain intensity), while the right panel reveals the wind speed obtained by Doppler.
The stormy complex begins as a wavy, solid arc of cells, which then quickly twists and extends to the south. A strong tide of descending wind was responsible for the transformation in the form of a bow. These winds were detected by Doppler radar in Stirling, Virginia, and shown by spots of orange on the front edge of the nose.
The image below reveals the peak strength of these winds – almost 88 mph, and in the range of 78 to 96 mph at other times. At this distance from the radar, the lowest scanning beam was several thousand feet above the ground, so these values do not reflect wind speeds on the ground. But they reveal the intense momentum in this downward flow – a large percentage of which has undoubtedly come to the surface to create damage.
The second complex developed south of Purcellville shortly after 4 p.m., expanding into a bow complex as it moved rapidly south. The trail of the storm took the core of the wind just west of downtown Warrenton, as can be seen in the radar circuit below.
442p: A dangerous storm hits Warrenton and could hit Culpeper shortly after 5p. This storm will knock down trees. Wind 60-80 mph. pic.twitter.com/0mss82gqJw
– Capital Weather Gang (@capitalweather) June 22, 2022
Peak Doppler wind speeds ranged from 90 to 95 mph, as shown in the following radar image:
Strong winds are the result of a rectilinear current called a downward blast, which occurs when an extremely strong downward current hits the surface and the airflow flows out along the ground, literally like a gust of wind. The strongest winds appear in the direction in which the storm is moving.
The large number of trees and the extent of the devastation look like a “dereho”, but in fact none of these turbulent complexes qualify as a dereho; derechos shall be determined by a minimum path of continuous wind damage of at least 250 miles.
Storm cell training and heavy rain
Some places in the region took a few inches of rain from this event, others not so much. Interestingly, the heaviest rains fell in long, parallel, narrow corridors oriented from north to south.
945p: Still a lot of rain going from north to south (yes – that’s unusual). Be careful to drive near streams and turn around if you encounter standing water. pic.twitter.com/lVgTmv0ZTZ
– Capital Weather Gang (@capitalweather) June 23, 2022
This type of situation can occur when the frontal boundary that serves to lift air in thunderstorms – in this case, an almost stationary front oriented from north to south – is aligned parallel to the steering flow established by a deep layer. winds above the ground.
The deep winds were from a very unusual direction for the end of June – to the north – as the jet stream, a river of fast-flowing air in the upper atmosphere, is in a strongly distorted pattern. A heat dome is placed above the southeastern part, and the jet stream along which the storms move moves over it, sinking sharply over the northeast.
Severe heat scorches southeast, with record highs forecast for Thursday
A dramatic radar image (above) shows one of these rain trains in action in the middle of the evening; the corridor stretches from Harrisburg, Pennsylvania, to downtown Washington.
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