Ramblings of a Graduate Student

The VORTEX 2 armada woke up this morning in Denver, Colorado with high hopes for a successful deployment. The forecast over the past few days seemed to indicate that the tornado potential today would be higher than it had been recently. Unfortunately, this did not turn out to be the case. I have to admit that other job responsibilities prevented me from following the weather evolution this afternoon, so I’m not entirely sure why the atmosphere was so devoid of severe thunderstorms in eastern Wyoming and western Nebraska. However, I do know that none of them (up to now and to my knowledge) have produced tornadoes.

With this said, the armada did target a transient supercell-like thunderstorm that developed near 00 UTC (7 PM CDT) in Goshen county, Wyoming. This thunderstorm appeared early on to be a fairly healthy, albeit small, supercell thunderstorm. Unfortunately, it appeared this thunderstorm was unable to draw warm, moist surface air up into it’s updraft. This result in the supercell to remain “elevated” and severely limited the rotation (tornado) chances. This was a real shame because the VORTEX 2 crew had what I consider to be their best deployment in the two years this project has been running. As far as I could tell, every radar was in position, ever mobile mesonet was in position, and all other assets were also in position. Too bad the atmosphere failed to cooperate. The image above is of the target storm moving east into Scottsbluff, Nebraska – a city that has been hit by severe thunderstorms nearly every night for the past several days. This is the town that VORTEX 2 sampled a brief tornado in just a few days ago!

In any event, forecasts continue to indicate that tornado chances are higher tomorrow than today, so the armada should once again have a decent chance at observing a tornado. Let’s just hope that if a tornado does develop, it is in an area where there are sufficient roads for the armada to collect data!

Well today was the first day of real operations.  The armada spent the night in Clinton, OK in preparation of a chase today in either SW Kansas or the southern TX panhandle.  During our 9AM conference call, we decided that the chance of severe thunderstorms developing in SW Kansas was pretty slim (due to a strong cap, or warm air aloft).  Thus, we targest an area NE of Lubbock, TX and SW of Childress, TX.   A big concern we had was a lack of shear (change of wind speed and direction with height) which would tend to cause thunderstorms to be “multi-cellular” and not the “supercell” storms that produce the majority of tornadoes.  However, after two days of not seeing anything, the armada decided to at least go see a thunderstorm.

The armada departed Clinton, OK around 10:30 AM with an initial target of Shamrock, TX, when an update would be provided.  Stopping there would give the armada a chance to head south, if needed, or continue on toward Amarillo where they could take the interstate to Lubbock.  On the way to Shamrock, the FC (field coordinator) made the call to head on to Amarillo and then head south via I27.   The armada arrived in Tulia, TX by early afternoon, where they spent most of the afternoon waiting for the atmosphere to decide what it wanted to do.  (Note, the Texas Tech group actually played a game of whiffle ball to pass the time!)

Thunderstorms began developing to the west of Lubbock around 4PM in a region of very dry low-level air.  This is bad for tornadoes.  Tornadoes need warm, moist air at the surface because this air is unstable and wants to rise.  A tornado, afterall, is nothing but a rapidly, rotating column of rising air extending out of a thunderstorm.  Additionally, similar to how sweating when you are outside is designed to keep you cool, rain falling into dry air causes the temperature to fall.  This rain cooled air then accelerates away from the thunderstorm causing the thunderstorm to become “elevated” above the cool air and reduces the chance of tornadoes.  Well the first storm that developed did just this.  It quickly became elevated and “gusted out”.

To the southeast of this initial storm (east, northeast of Lubbock) a cluster of new thunderstorms developed in an area of slightly better moisture.  The armada was faced with a very tough decision: Go after the elevated, but better looking storm to the north, or take a chance on the weaker storm in a region of slightly better moisture.  The armada waited as long as they could to make a decision…even moving east from Tulia to Silverton, TX…but ultimately waited a little too long.  They tried to head north to the initially better looking storm, only to get hit with the cold air coming out from this storm.  Meanwhile, the storm to the southeast began to look  a lot better.  The armada then tried to catch back up to the eastern storm, but essentially was playing catch up the entire time.  In fact, in addition to playing catch up, the armada spent a considerable amount of time dodging storms that were developing all around them that began producing hail.  I should also mention that our communication systems do not work very well in this part of the country.  Cell phones were having a hard time keeping signal, and the canyons made it difficult for our line-of-sight radio signals to make it to the appropriate personnel.

Eventually the armada made it to the city where they were spending the night (have to read tomorrow to find out where!) and decided that even though a nearby storm was looking “interesting” they would end operations for the night due to everyone being exhausted from a long day and night was falling.

Here in the VOC, we spent most of the day preparing forecasts for today’s operations and planning for tomorrow’s operation.  It appears now that the armada will be operating somewhere in western Oklahoma in hopes that a storm can develop along the southern edge of what is feared to be a pretty strong squall line.  Model forecast fields indicate the presence of extreme instability in Oklahoma, so very large hail will be a very big concern.  Depending on the evolution of tonight’s thunderstorms, there might be a small tornado risk in this area as well.

We’ll see what happens!