|This area shows pictures taken from the infamous series of severe thunderstorms affecting the areas near and around Saint Louis, Missouri during the period from July 18 through Junly 21, 2006. Most notably, a major progressive derecho crossing Illinois to the southwest slammed the City of Saint Louis directly during it's journey on July 19, 2006. This became a very destructive wind storm unleashing large hail and winds up to 95-MPH, or more! Extensive damage was caused by this event alone, leaving several people dead, power out to over 500,000 people (some for over a week), and damage in the millions. Another similar storm, an HP supercell and bow-segment produced another round of 80-MPH plus winds and hail on July 21, over nearly the same areas affected 2 days prior. These two major events also produced isolated tornadoes as well. I did perform a few interceptions on these extreme severe weather events (commonly called XDW for eXtreme Damaging Wind) near Saint Louis and neighboring Illinois as well as southwestwards to the Ozark foothills. Details with pictures appear below on these events.|
Severe weather abounds during the spring, summer, and even fall in portions of the Central United States. In July and August, most severe weather occurs in the upper plains and northern Midwestern USA (such as Illinois). The week of July 18 through July 31 was no exception as some rather strong and interesting events unfolded. The first began as a bow-echo system of severe thunderstorms in SE Minnesota on July 19. This storm propagated east, then southeast, and then towards the south and southwest causing a swath of wind damage from NW Illinois then through and past Saint Louis, Missouri. Another wind and rain event occurred closer to Saint Louis on July 21, farther damaging and insulting what damage was done on July 19. These events are broken up based on chases conducted during the same week and are shown in greater detail below.
The image above is an annotated diagram showing both the reflectivity (left) and storm velocity (right) of a supercell storm about 60 miles southwest of Saint Louis over the Ozark foothills (near Reynolds County). The small but intense storm developed along a boundary with northwest winds aloft providing the directional shear necessary (note the storm oriented NW to SE). The storm was producing penny to nickel sized hail and 70 MPH winds as this image was being processed. The storm is on the limit of the WSR-88D range, that's why the "no data", depicted by magenta, appears on the lower portion of the storm. The storm eventually produced golfball-sized hail and 80-MPH winds near Reynolds County, then later, baseball-sized hail near Texas, Missouri! The storm is moving SOUTHWEST (deviant right moving) due to a motion vector between the NNW flow aloft and westward advancing boundary.
|Here is a view of the updraft side of the developing supercell storm in Missouri. The view is to the west, and notice the updraft is on the NW side of the storm. Also visible is the tilting (or slanting) of the cumulus towers in the foreground, due to directional shear. Also note the crisp edge of the anvil to the upper-right. The core of the storm is to the left.|
|Here is the wall cloud (with possible funnel clouds) looking south near the main updraft of the supercell. Note the "stinger" inflow cloud extending from the wall cloud (center) to the left. The green hue is caused by hail, behind the wall cloud, about golfball-sized at the time this picture was taken. Also, interesting in this picture, looking south, winds are blowing from the left to right, indicating rotation (mesocyclone). The storm rotated hard, but did not produce tornadoes.|
|Here is some tree damage produced by the 70-80 MPH winds associated with the core of the supercell storm. The storm also knocked out power as well.|
|A nice display of mammatus clouds also appeared on the backside of the storm complex at dusk.|
The image above is from the Storm Prediction Center's product on storm reports for July 19, 2006. What is quite interesting are the numerous reports of blue dots (wind damage) that arc from Minnesota, through Illinois, then cross St Louis into Missouri. Green dots indicate hail reports, and red ones are tornadoes (due to embedded supercells). The black square indicates where winds over 75 MPH (65 Knots) were reported. Also note the "curved" shape of the damage reports, denoting an initial SE motion, then turning south and SW later.
The annotated radar image above shows the bow and progressive derecho as it was blasting towards the southeast in Illinois and about 50 miles northwest of Springfield. One key feature in both the reflectivity image (left) and velocity image (right) is the radar presentation of the powerful gust front associated with this storm system. In the reflectivity image, the gust front shows ahead of the heavy precipitation cores as an arc shaped curved line. In the velocity image, yellow shades appear as inflow appear ahead of the gust front (away from the radar) as darker shades of blue appear behind it (indicating at least 60 Knots of outflow winds towards the radar)! Also note a small velocity couplet (blue next to yellow) appears on the velocity image denoting rotation in one of the intense cells in the line (embedded supercell) correlating by higher reflectivity in the image to the left. This HP supercell helped maintain the bow and derecho structure and allowed it to back-build to the south, and eventually, southwest.
Here is an annotated diagram of both reflectivity and velocity imagery just before the storm system, and associated derecho, was about to move into the Saint Louis metropolitan area. Note that the winds in the velocity image are near 80 knots! The core of the southern and southwestern cell (maybe a "tail-end charley" HP supercell, is higher than 65 dBz, indicating large hail.
About the same time as the radar image(s) above, this is the storm complex in both visible and color-enhanced infrared channels. Note the impressive overshooting tops of the storm complex, especially on its SW side, as well as very cold (very high) cloud tops colder than -70 degrees C.
|This is a view of the sun about 30 miles south of Springfield, Illinois while heading north in Interstate 55. The "watery" appearance is caused by the sun filtering through high cirrus and ice clouds that are blown off from thunderstorms in the rapidly approaching storm complex, which was about 50 miles away then this picture was taken.|
|Here is a view of the intense lead gust front about 5 miles south of Springfield, Illinois while headed north on Interstate 55. The gust front had winds gusting well over 70-MPH at this point.|
|Here is another view, looking out from inside the storm, of the intense lead gust front while headed south on Interstate 55 out of Springfield, Illinois. 70-MPH plus winds associated with this gust front preceded the arrival of rain and hail. Note the dust getting kicked up.|
|Visibility drops to near zero in ferocious 80-MPH winds and hail mid way between Springfield, Illinois and St Louis, Missouri just west of Interstate 55.|
|Here is another picture, taken in the northern portions of St Louis, Missouri, of a line of cars trapped as trees and powerlines fall on the road. Note the car turning around at the head of the traffic jam. Winds gusted to near 100-MPH in this portion of the storm system.|
The annotated SPC storm reports product above clearly shows the path of wind damage (blue dots) extending from just NW of St Louis, Missouri to southern Illinois. This storm system began as a bow-segment with an embedded HP supercell (mesocyclone). The HP storm strengthened within this line, and produced another round of winds over 80-MPH (denoted by black squares, one right over St Louis). An additional 250,000 people lost power from this storm system in St Louis alone, in the SAME areas affected by the derecho event 2 days prior. Note the tornado report (red dot) in Illinois as the HP supercell did spawn a tornado as well.
|The HP storm arrives at about 11 AM in the NW suberbs of St Louis (near St Charles) with 60-70 MPH winds. In this picture, flags are being blown by the strong winds.|
|The storm continues to intensify as it moves eastward at nearly 50-MPH. Winds easily gusted over 80-MPH with hail to golfball sized. In this picture, a large tree branch became airborn and came to rest in a power pole.|
|Strong winds and hail whip sideways as in a hurricane. Many road signs and construction equipment was blown over.|
|In this picture, you can see the sheets of rain blasting across the roadway at well over 70-MPH. The objects in the background are construction signs that were also blown over.|
|The storms caused extensive flight delays, and I myself became affected as I had to fly home to FL on the evening of July 21. A two hour delay, due to weather, caused me to miss my connection in Atlanta, causing another 8 hour delay and frustration. From the air, once above the low clouds and out of St Louis, the flight path had to cross the same complex of storms that passed through St Louis earlier. In this picture, the canopy of anvil clouds can be seen barely visible by the setting sun at about 25,000 feet. The active thunderstorm cells themselves are to the far right in the picture.|
|While flying through and around the complex of storms, somewhere over Kentucky / Illinois, snowflakes become visible - Illuminated by the wing-tip strobes and anti-collision lights. Lightning was all around us too and made for a very bumpy ride.|
|Here is a picture, illuminated by lightning, of a descrete thunderstorm cell where the cumulus structure is revealed. This was just after getting past the worst of the storms, at 33,000 feet somewhere over Tennessee.|
|Now farther away from the line of severe thunderstorms, and beginning our descent into Atlanta, lightning illuminates the active cells in the line like a "string of pearls". The yellow "glow" in the clouds to the right is from the lights of Atlanta, Georgia.|
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