Severe Weather Pummels the Region - August 18-20, 2011


August 18, 2011

After what has been a quiet past few weeks with a lack of widespread severe weather in the region, conditions rapidly changed on Thursday as a favorable setup for severe thunderstorm activity developed in the mid-section of the country.  Very warm and humid air lifted northward into the region, while cooler air lingered in the western Great Lakes.  The battleground between these two types of air mass established itself from Nebraska to western Iowa, northern Kansas and northern Missouri.

Our first round of severe thunderstorms developed during the evening and overnight hours of Thursday August 18, 2011.  Scattered supercell thunderstorms developed over eastern Nebraska and western Iowa, producing very large hail and heavy rain, widely impacting the Omaha metro.  While this soon to be large cluster of thunderstorms was beginning to develop over western Nebraska, an isolated supercell drifted towards the city of Maryville, MO.  As this storm rolled through the city,  winds greater than 80 mph even approaching 100 mph created extreme damage.  This storm crushed numerous corn fields and produced extensive hail damage.  Quickly filling in behind this supercell was the aforementioned developing mesoscale convective system (MCS) capable of producing extreme winds.  This system quickly became organized and pushed from north to south down the Missouri river Thursday night.  Winds were estimated between 60 and 80 mph, as damage was reported from St. Joseph, to Leavenworth and across the Kansas City metropolitan areas.  Extensive tree and powerline damage was reported with upwards of 100,000 customers without power at the height of the event.  This storm system even knocked down the primary radio tower for the Missouri State Patrol in St. Joseph, MO.

This thunderstorm complex continued to push south and east, finally reaching the Missouri State Fair around 1 am Friday morning.  Measured winds of 62 mph caused havoc at the fairgrounds, blowing over tents and leading to the evacuation of the nearby campers and campgrounds.  Damage cleanup at the fairgrounds caused the fair to open up their gates well into the daytime hours of Friday.

Radar Animation - Click on the Image for a Larger Version  


August 20, 2011

After a quiet day on Friday, thunderstorms once again developed late Friday evening along a boundary of very warm temperatures in the Southern Plains and cooler temperatures in the Mid-Missouri River valley.  This time, a developing cluster of storms over east central Kansas rapidly transitioned into a wind producing MCS as it approached and crossed the Kansas City metro.  Ahead of this complex however, a very strong storm dropping south out of Nebraska first produced extreme hail the up to the size of 4.5" in the city of Leavenworth, KS. This storm however decreased in intensity as it entered Kansas City, setting the stage for the strong wind producing MCS in east central Kansas to become the main threat.  Measured wind speeds between 60 and 80 mph raced through the Kansas City metro with this second system, causing additional tree and power line damage leading to even more power outages. 

As this storm system moved eastward it did begin to weaken, however was still able to produce upwards of 50 mph winds at the Missouri State Fair. 


Radar Animation - Click on the Image for a Larger Version  

 While the severe weather conditions were not liked, much of the area did received highly beneficial rainfall.  The Kansas City International Airport (KMCI) recorded a record daily rainfall for the 20th of 2.40", breaking the previous record of 2.17" set back in 1964.  Throughout the 3 days of thunderstorms KMCI recorded 3.90" of rain, finally jumping the location back above normal for the year. Rainfall reports were just as generous over the remainder of the region, with upwards of 2-4" in most locations during the past 3 days.

7 Day Regional Rainfall Totals (please click on image for larger version OR Interactive Map)

Severe Weather Report Maps:

Please click on each image for a larger version, or if you want to see specific storm reports in an interactive format please click on the link embedded below the pictures.

August 18-19, 2011 Click here to view the interactive map August 19-20, 2011 Click Here to View the Interactive Map



Damage Photos from Maryville, MO - August 18, 2011


Damage Pictures from near Maryville, MO
Estimated Wind Speed 80-100 MPH
(click to enlarge)
Vinyl Siding Damage Maryville Water Dept Building Roof Damage From An Old Building
Siding and Roof Damage N Of Maryville Roof Damage 1 Mile East of Maryville Gas Station Canopy Winston, MO

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