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4/30/10 and 5/1/10 Chase Recap: Arkansas High Risk Bust

Chase Stats
SPC Outlook: HIGH
States Driven: MO, AR, MS, TN
Departure City: Pevely, MO
Target City: Stuttgart, AR
Ending City: Blytheville, AR
Outcome: Lowering/Wall Cloud
Chase Pics: Gallery

*Please note the stats above are only for 5/1/10*

April 30th was a Friday, and I could not get out of class until 2:15PM. The SPC had upgraded most of IL into the MDT category, and I was eager to chase. We left right after class, and headed towards Chicago. A big blob of what was probably elevated crapvection was pushing east from Davenport, IA, and a few discrete cells were forming in IL. We then headed south on I-55 towards Bloomington, and then west on Highway 24 towards Eureka, and Peoria. A cell was coming up from the south towards Peoria, so we decided to intercept it just south of Peoria. The storm was nothing spectacular, and we didn't even see a shelf cloud. Continuing south on 24, storms were firing down in AR, and were going tornado warned. The MD that the SPC had outlined was way too far north for this day. I looked over some models, and outlooks for the next day, and decided it would be a good day to chase tomorrow in eastern Arkansas. We got back on I-55, and headed south towards St. Louis, MO. Eventually after checking with like 5 hotels we got a room south of St. Louis in Pevely, MO, which would also make for a little shorter drive the next day.

Essentially April 30th was more of a driving day, as there were no spectacular storms. Waking up in the morning, we headed on our way south towards Arkansas. The SPC had issued a High risk for the day, and I was excited, as it would be my first High risk chase. Blytheville, AR was our first stop, and we filled up on gas, and got some snacks. I highly recommend the Jack Link's Matador snack sticks, they are tasty! We continued south, until we hit I-40, where we headed west. By now there was a nice boundary showing up on radar just the southeast of Little Rock. This boundary was oriented in a SW to NE fashion, so I decided to head a little farther south than Brinkley, and head towards Stuttgart, AR. We topped off the tank in Stuttgart, and headed southwest out of town, where we met up with Ben Holcomb. Soon we had a few other chasers stop by including Kevin Crawmer, Jesse Risley, and Mike Brady. A moderate cap was still in place over much of the area, and it was slowly eroding as time went on. Eventually all broke loose, and numerous cells started firing in southern Arkansas.

We waited a little bit, and then targeted the cell in the SE corner of Arkansas. We chose this as it looked the beast of the cells that were out there, and it had all the clean inflow into it. There were no other storms around it to rob it of its inflow. After crossing the Arkansas River, the terrain became less favorable for chasing. There were many more trees, and it was pretty difficult to find a clear open spot for viewing. We never did find a great spot for viewing, although there was a slight clearing just northwest of Monticello, AR. We watched the storm come towards us, and observed a nice bowl shaped lowering. It was rotating nicely, but never fully condensated to the ground, nor was there a debris cloud. Our shortcut to keep up with the storm was cut off when we found out the road had a gate across it. This would be the last chance at keeping up with the storm, as storm motions were around 65mph. The rest of the night we played catch up, driving through Arkansas, into Mississippi, and then up towards Memphis, TN were we abandoned the chase. We then drove back up to Blytheville, and stayed the night at a Super 8.

We did see a nice supercell, with wall cloud, but overall the day was a High risk bust. I will follow up with a little post storm analysis on possible reasons why these storms for the majority did not produce tornadoes.

Here is the 0z sounding taken at the NWS in Little Rock that night. As you can see, there is plenty of CAPE, and a good amount of shear in the atmosphere for supercells. There is plenty of helicity (turning of the winds with height), and lapse rates on this sounding aren't too bad. Surface winds are also lacking as you will see later.

The two animations above of base reflectivity, and visible satellite show an explosion of cells around 0z. For sustained supercells, you want them to be as discrete as possible. The more cells you have, the more they inhibit other cells-they sort of compete for the atmosphere. Congestion of cells on that day may have inhibited supercells from getting the "key ingredients" needed to sustain a mesocyclone and/or tornado.

Low level lapse rates around storm initiation were terrible. As shown above, they were around 5.5 to 6 C/km. Steeper lapse rates create more buoyancy, and enhance the updraft. This is crucial for supercellular development.

Shown above are charts of dewpoint temperature, as well as surface winds. Arkansas had plenty of moisture, around 75 C in the SE quadrant of the state. Surface winds are also very weak, and will not enhance the updraft, and allow fast rising motion. It appears that maybe the two biggest factors may have been the low level lapse rates, and the surface winds all being below average, and contributing the weaker updrafts.