...Straight Line Wind Damage Hits During the Overnight Hours - June 11, 2009...

Yet another severe thunderstorm pummeled portions of extreme Northeastern Kansas as well as locations south of St. Joseph, MO during the overnight hours of the 10th.  This storm developed ahead of a weak mid-level wave which was crossing the lower Missouri River Valley after midnight.  As the storm developed across western portions of Atchison County in Kansas and then began to collapse across eastern portions of the county, it produced strong wind damage near the city of Atchison and further east towards Rushville and DeKalb.  Earlier today, a NWS storm survey team travelled to the impacted areas, reporting all damage which occurred was due to straight line winds and microburst winds greater than 60 mph with other damage created by large damaging hail.  These winds were strong enough to overturn a camper trailer just east of the city of Atchison, KS injuring the occupants of the trailer.  This storm also produced damage to a grain bin, along with fairly widespread flattening of brush, grass, and crops in the area.

The following are images of the estimated storm track, along with the radar indicated path of the strongest winds associated with this storm.  There is likely additional minor agricultural damage from this storm (white shaded area)  not indicated on these maps. 

Storm Track of highest winds Storm Track
Image of Storm Track and Potential Wind Damage Storm Track as Indicated by Reports

 

This isolated storm continued to track across northern Missouri through the night, and while the wind damage subsided, this storm still produced tennis ball size hail further east towards the city of Holt, MO.  Radar Images below capture this storm at its strongest points, with image A showing the intense outflow of winds as this storm initially collapsed near Atchison, KS.   Image B depicts this storm further east, depicting how the winds spread out away from the core of the storm with some redevelopment displayed. Finally image C depicts the storm as it recycled and restrengthened to produce tennis ball size hail near Holt, MO.

 Click on the Image for a Larger Version Click on the Image for a Larger Version  Click on the Image for a Larger Version 
 Image A: Initial Strong Winds
 Image B: Storm Continues to Spread
 Image C: Redeveloped Storm

The radar image timelapse below shows a 3D rendering of the wind storm at it moved across Atchison, Buchanan, and Platte Counties early this morning.  3D rendering allows weather forecasters to view a specific storm at multiple angles and view only certain portions of the storm to look for certain characteristics.  Forecasters will often look at how high a certain reflectivity is above the ground and above the freezing level of the storm.  Large (or high) reflectivity values above the freezing level in the atmosphere indicate the presence of a large amount of scatterers (what the radar beam bounces off of).  These scatterers (both raindrops and hail) also provide valuable information about the winds at a certain level.  At the height of this storm, the freezing level was around 12,000 ft AGL, with the Pleasant  Hill radar indicating 70 dBZ reflectivity levels above this level for a sustained amount of time prior to the onset of strong winds.  What these images also show is that this core of high reflectivities began to decend as it crossed Atchison, KS as the updraft of the storm was no longer able to sustain the high volumes of scatterers aloft.  The strong downward motion of these scatterers, as indicated on radar by descending reflectivities, is a strong indication of damaging straight line winds rushing downward in the core of the storm. 

Time: 1140 PM CDT Time: 1144 PM CDT Time: 1149 PM CDT Time: 1153 PM CDT


Damage Photography:

Several images of the storm damage have been taken this morning.  Below you will find both from the NWS storm survey as well as photos submitted directly to us at the National Weather Service.

Tipped Over Trailer East of Atchison Corn Damaged by Large Hail
Trailer Tipped Over Near Atchison, KS Corn Damage From Large Hail
Grain Bin Damaged by High Winds Uprooted Tree Damage
Grain Bin Damaged by High Winds Uprooted Tree Damage

 Hail Photography:

Hail Images Courtesy WDAF FOX4: Holt, MO Hail Images Courtesy WDAF FOX4: Holt, MO

 


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