Sunday, April 25, 2010

Mississippi Tornado Outbreak of 4-24-10 - Part II

Below are screenshots of Nexrad Level II data, corresponding as closely as possible to the damage reports that I highlighted on the Part I blog (map #3) concerning yesterdays tornado outbreak across Mississippi.


Unless otherwise noted, all images were taken from the Jackson, MS (DGX) radar and depict the 0.5 degree elevation scan.  


The first shots are from 16:09Z (11:09 a.m central time) when the first tornado damage report was received near Tallulah, LA:


16:09Z (11:09am) Reflectivity Image


Corresponding Storm-Relative Velocity Image



Now we'll jump ahead about 50 minutes, as the dangerous storm was approaching Yazoo City (where extensive damage, numerous deaths and injuries were about to take place) from the Southwest:

17:00Z (12 Noon) Reflectivity Image

Corresponding Storm-Relative Velocity Image


 
17:05Z (12:05pm) Reflectivity Image

Corresponding Storm-Relative Velocity Image


17:09Z (12:09pm) Reflectivity Image

Corresponding Storm-Relative Velocity Image

About this time (17:09Z/12:09pm central time) is when really interesting signatures began to appear on the radar imagery, unfortunately the result of the intense damage that was being done in the Yazoo City area.

When examining the above storm-relative (SR) velocity image with a slightly different color scale, you can actually begin to see a "donut-hole" that emerges immediately Southwest of the center of Yazoo City:

Another view of the 17:09Z Storm Relative Velocity Image



Shortly thereafter, on the 17:14Z (12:14pm) images, you can also begin to see the enormous debris field being carried by the circulation show up on the reflectivity imagery as well:

17:14Z (12:14pm) Reflectivity Image

Corresponding Storm-Relative Velocity Image


The 17:19Z (12:19pm) imagery shows the deadly storm exiting the immediate Yazoo City area.  So much debris has now been sucked up by the storm that it is even more evident on the reflectivity imagery: 




Corresponding Storm Relative Velocity Image.  Small white circle depicts approximate location of the debris field indicated on the corresponding reflectivity image.



17:50Z (12:50pm) Reflectivity Image.  Note small debris field still visible, noted by white circle.

Corresponding 17:50Z Storm Relative Velocity Image.  Small white circle shows approximately location of the debris field indicated on the corresponding reflectivity image.


With the storm now nearing the outer limits of the most effective range of the Jackson radar, the images as the beast nears the French Camp area are not quite as crisp and telling, though you can still clearly see a well-defined circulation center on the velocity image.

 
18:27Z (1:27pm) Reflectivity Image

Corresponding Storm Relative Velocity Image


Shortly after 2pm, the storm passed about 5 miles North of Starkville.  We've had to switch to the Columbus AFB radar (GWX) for the following images.  Keep in mind there are thunderstorms ongoing over and near the radar site, so at least some minor distortion of the imagery is likely.

19:06Z (2:06pm) Reflectivity Image from the Columbus AFB (GWX) Radar

Corresponding Storm-Relative Velocity Image

I'll probably make at least one more radar-specific post after more of the ground-truth reports and survey data are in...








 

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