Storm Chase 6-19-09 (this may take a few moments to load....there are lots of pictures)

Please note that we are trained professionals and storm chasing should not be done by just anyone. If a storm is nearing please take the appropriate measures of taking shelter in a sturdy structure away from all windows in the central most part of the building. Do not attempt to recreate any of the actions taken by the chasers.

Area Covered (click the image for an interactive display on Google Maps):

On Friday, June 19th a major and widespread severe weather event was predicted by the Storm Prediction Center. Although the main risk was widespread damaging winds and large hail, there was a minimal risk for tornadoes in the southern Great Lakes region. Travis Swiger and I decided to chase on this day as there was both good directional and speed shear through the lower atmosphere that would allow updrafts of any individual cells to rotate. There was also going to be outflow boundaries from the cold pools left behind from early morning convection. This convection was expected to cross the northern half of Indiana and Ohio leaving the boundary through the mid-to-southern sections of these states. Upon waking up on Friday morning, strong to severe thunderstorms were traveling southeast across Ohio from northern Indiana and southern Michigan. These storms had very heavy rain, constant cloud to ground lightning, strong winds and even some hail (1.00" hail reported in Logan-Hocking Co and Lancaster-Fairfield Co). These storms caused flash flooding and streams and rivers to reach and sometimes even overspread their banks. This was the expected convection that would lay down the elements for tornadic activity later in the west that we expected to occur. Soon after the storm in Athens was over we proceeded to take on our trip out to western Ohio/eastern Indiana and stop in Dayton to wait for afternoon storms to fire.

As we were leaving Athens Co we saw some of the flash flooding occuring just north of Nelsonville on U.S. 33. Remeber that you should never cross flooded streets. We did because we had no choice, there was to much traffic to turn around and were forced through it. Luckily we didn't get into any trouble. The slogan of the chase, "turn around, don't drown".
Here is the U.S. 33 flooded that we were forced to cross:
Click all the images for the bigger, more detailed image.

Here is a swollen creek north of Nelsonville:


We arrived in the Dayton area around 12pm. Upon looking at data, we were pleasantly surprised. The boundary was shifting south as planned and another boundary was drapped over northwest Indiana to southern Illinios. This would give us an area of boundary intersection and convergence in northern/north central Indiana, an ideal area for storms to develop. LCL's were much lower than previously thought and surface winds had increased more than expected out of the south/southwest creating more lower level shear. Bulk shear had also increased to 50+ knots. Coupled with dewpoints shooting up to the lower to mid 70s and ongoing surface heating allowing temperatures to reach the high 80s low 90s were increasing the chance of tornadic and isolated supercells. The Storm Prediction Center seemed to agree as half an hour later they increased the probablity of torndoes to 10% in the central region of Indiana and a tornado watch was issued. With this information we decided to cross the border and head into Indiana to get in better position for storms firing later.

We decided to start to swing north, closer to the intersection of the boundaries along Indiana SR9 and to avoid the metropolis of Indianapolis. There had been a consistent cumulus field since we entered Indiana that was just begging for convection but the cap held firmily not allowing vertical development and permitting more surface heating. We stopped in Anderson to get another look at the current conditions in the atmosphere. The cumulus field had actually begun to fall apart and clear skies were beginning to rule worring us that the cap may not break. Luckily another cluster of storms had developed over extreme northern Indiana and southern Michigan a few hours before hand and moved east into northwest Ohio. This played well because since the old boundaries had time to mix out they weren't going to help us anymore. Instead, this new cluster laid down a new boundary in northern Indiana that was beginning to become the focal point for convection around Plymouth. We decided to start heading north as this may be the only chance we would have in daylight. The cell quickly became stronger and went severe warned. We began hustling as we were about 100 miles away from the cell. On our way north the storm went tornado warned and began a right turn, classic supercell characteristics for tornadoes. This worked in our favor as the storm was coming towards us and would cut down on the time and distance to reach it.

We made it to Wabash, IN and coming into the city we saw the updraft towers about 30 miles away. Thank goodness for flat terrain as it allowed for so much visibility. The storm remained alone and didn't have any other cells to interfere with it. Here was the updraft tower shooting up into the anvil of the storm in the background behind the weak cumulus:

Here is the radar grab from the storm at that time:


It was a classic supercell with a hook on the southwest side and a unique V-notch in the other part of the storm facing east (white v symbol) that is a characteristic of a strong supercell. The storm was moving along the old outflow boundary (labeled by the purple line with dots), had its own cold pool being wrapped around it (represented by the blue cold front line and blue arrows), had a distinct hook on it (represented by the purple occluded front line), and had strong southernly wind flow pushing warm moist air into the storm (red arrows). The area of convergence (a mini, microscale low) of all the winds is where the occluded front is, within the hook, and is the most likely place for a tornado to occur in this tornado warned storm.

Shooting out of Wabash we finally got our first look at the base of the southern portion of the supercell looking north. A feature that was very interesting was the top of the updraft tower. It was shooting up and actually breaking off the initial anvil leaving a small break of blue sky between the overshooting top and the anvil.I have never heard or seen of this happening before, but it sure looked neat!


Getting closer we saw the remnants of the first mesocyclone:


Here is the radar shot of the coinciding radar:


After finally finding a road that went east the mesocyclone began to tighten up:


Here is the radar image of the shot:


We were lucky enough to get to see the storm go through several cycles and produce several rotating wall clouds and a funnel. The second meso development was the closest to producing the tornado as it dropped a funnel towards the ground. Here you can see the RFD (Rear Flank Downdraft) wrapping up into the meso tightening it:


And is shown here on radar and by the corresponding couplet on velocity:



Although the couplet on the base velocity doesn't appear that significant and is quite broad, looking into the upper levels of the storm you can see very rapid and tight rotation in the couplet:


All these images are from the southwest of the storm looking east/northeast into the hook portion of the storm. Here is the quick funnel that dropped with the second mesocyclone:


The funnel quickly dissipated and a new RFD began to cut into the newly developing meso as the storm cycled quickly. This RFD could be seen by the clear slot cutting into the clouds from the top left to the middle right:


A much stronger rotating wall cloud began to take shape at the base of the new, third mesocyclone. Although it never produced a tornado or even a funnel cloud it was very photogentic. Here is the wall cloud wrapping up even more:


A tail began to form on both sides showing the strength of the updraft and its drawing moisture in from around it as it rotated. This would eventually lead to its death as it drew in cooler air from the FFD (Forward Flank Downdraft) and the end of the tornadic potential to the storm. Here is the rapidly rotating wall cloud with tails, take note of the clear slot of the RFD still very much evident:


You can see the hook still very much evident on radar and the multiple mesocyclones in different stages by the couplets on the velocity:



You can also see an area of heavier precipitation in the upper level of the storm not noticable from the base radar scan when compared above. This is an area of hail and rain being suspended by the strong updraft, also known as the BWER (Boundary Weak Echo Region):


Finally the last mesocyclone that developed in the final cycle of the supercell's life developed. It was weak but hung low and was very ominous overtop of Huntington:


The weakening couplet can be seen on velocity, and the shrinking hook on radar as it tried one last time to develop a tornado:



We then had another first occur as the supercell rapidly died off. The rotation began to go horizontal in the upper levels as it became outflow dominant. This forced the rotating updraft to take on a very unique look as a roll cloud. I personally have never seen one before and it was very stunning. You can even see the spiral of the rotation vividly as it goes into whats left of the thunderstorm.


Here is the coinciding radar and velocity scans for that time period:



After that picture the supercell completely died off. It went from a severe thunderstorm to a bunch of precipitationless high clouds in the matter of twenty minutes. It has to be the quickest death of the storm that I have ever witnessed. In its time however, it was a very beautiful storm, especially for a local chase. Here is the radar scan not even 25 minutes after the last radar scan above:


An interesting note on the sudden death of the storm. It seems that the storm followed the outflow boundary from the earlier cluster through its whole life. As time went on the boundary farther towards the east had more time to mix with the surrounding atmosphere. Looking at radar you notice that right before the storms death the boundary is no longer noticable on the radar. My theory on the death of this storm is that with the boundary mixing reduced any or all convergance that was possible along the boundary and therefore not permitting an updraft to contine for the supercell.

Here is the full life cycle of the storm on radar, about a two hour loop:


All in all, the trip lasted about 13 hours. We traveled around 600 miles. Although we didn't get a tornado we put ourselves in the absolute best position we could of and would have been witness to one had it occured. There was a reported tornado a few minutes before we got on the storm by the public, however, there has been no confirmation as there was no damage found in the vicinity of the report as of Sunday 6/21/09. Here is the storm reports from that day to end things.



Christopher Redmond
cr898005@ohio.edu

Travis Swiger
ts280204@ohio.edu