Thursday, June 25, 2015

48 Hours of Storms in 6 Weather Images: Midwest Derecho, Tornadoes and Northeast Severe Thunderstorms

Jon Erdman
Published: June 24,2015

True to June's form, a 48-hour period from Sunday night through Tuesday night spawned tornadoes, a derecho in the Plains and Upper Midwest and a  squall line in the Northeast that knocked out power to hundreds of thousands.
(MORE: Northeast Severe Weather Recap | Midwest Tornadoes/Derecho | What is a Derecho?)
The weather imagery from this severe-palooza was impressive. We geek out a bit and share some of our favorite images from the events.

Intense Winds Detected By Radar

Doppler velocity (left) and reflectivity (right) from the NWS-Sioux Falls Doppler radar at 4:59 a.m. CDT on June 22, 2015 centered on Garretson, South Dakota, just northeast of Sioux Falls. Annotated at left are radar-detected wind speeds aloft. A subsequent NWS storm survey estimated surface winds up to 100 mph in Garretson.
(NWS-Sioux Falls, South Dakota)

"Fried Egg" On Satellite

The Midwest derecho on June 22, 2015 is hard to miss in this infrared satellite image taken at 8:15 a.m. CDT. The pink shadings over northern Iowa and southeast Minnesota correspond to the highest cloud tops associated with the most vigorous thunderstorms. The NWS-Des Moines office noted those highest thunderstorm cloud tops were as cold as -114 degrees Fahrenheit. Thunderstorm clusters with this distinct satellite signature are known as mesoscale convective systems.

Supercells (and Waves) Visible From Space

Visible satellite image of supercell thunderstorms in Iowa and Illinois at 7:15 p.m. CDT on June 22, 2015. Albia, Iowa was struck by an EF1 tornado about 22 minutes prior to this image. About an hour prior to this image, an EF3 tornado struck southwest of Marysville, Iowa. Four minutes after this image, a tornado was reported near Edgington, Illinois. Notice the overshooting tops, indicative of the severe thunderstorms in progress, as well as the gravity waves produced atop the cirrus shield from the overshooting tops punching into more stable air, initiating those waves.

Northeast Squall Line From Space

Visible satellite image of the squall line of severe thunderstorms racing through the MId-Atlantic states on June 23, 2015 at 6:00 p.m. EDT. Near the time of this image, a 72 mph wind gust was clocked at Philadelphia International Airport and the line of storms was moving into the Washington, D.C. metro area. As of early afternoon the following day, 419,000 customers were still without power from the severe thunderstorms.

South Jersey "Commahead"

NWS-Mount Holly, New Jersey, Doppler radar with 3D enhancement over southern New Jersey on June 23, 2015 at 7:05 p.m. EDT. Notice the sharp bookend vortex - rotating commahead - in red in the top-center part of the image. This bow echo was responsible for numerous wind gusts from 65-75 mph across southeast Pennsylvania and southern New Jersey downing trees and power lines, and damaging the roof at the Seneca High School gym in Tabernacle Township, New Jersey.
(Sarah Dillingham - The Weather Channel)
 


Tallying the Reports

Locations of high winds/wind damage (blue triple-arrow symbols), tornadoes (red tornado symbols) and large hail (white circles) from the evening of June 21 through June 23. According to the Storm Prediction Center, using a method to filter out redundant reports of the same event, there were roughly 800 reports of severe weather over that time period in the U.S. The majority of these were associated with the Midwest derecho, tornadoes, and Northeast severe storms, though a number of pulse severe thunderstorms with bursts of high winds also occurred in the Southeast U.S. during that time.
(Storm Prediction Center, Google Earth)

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