Ramblings of a Graduate Student

As I mentioned in yesterday’s post, it finally happened.  The VORTEX II armada captured a tornado.  They started out the day in Sterling, KS and were faced with the decision of staying in the same general area / heading slightly SE or heading up NE of the Cheyenne ridge.  Field coordinator David Dowell and myself gave passionate arguments for targeting Wyoming which helped turn the tide…and this is what the armada did.

They started out by heading to Kimball, NE (which is in the far southwest county of the NE panhandle) and watched thunderstorms develop to their west.  As the thunderstorms moved closer to the armada, it became clear that the southern most storm had developed supercellular characteristics.  After a brief discussion, the armada decided to make this the target storm and they deployed on it.  As they approached the storm from the east, the National Weather Service office in Cheyenne, Wyoming issued a tornado warning on the storm.  While the storm was not producing a tornado at that precise moment, the storm certainly looked like it was getting ready to produce one.  The Weather Channel broke in to their regularly scheduled program began streaming live video of the supercell thunderstorm.

As the armada sent probes 1, 2, and 3 into the region of the thunderstorm that was about to produce the tornado, very large hail began to fall on the vehicles.  In fact, probes 1 and 3 received so much hail that the damage forced them to abandon all other missions for that day.  They were forced to stay behind the armdada and have their windows repaired.

While the probes were being pelted by hail greater than 4.50″  (softball size), the supercell began to develop a rapidly rotating wall cloud that went on to produce a tornado (carried live by the Weather Channel).  The storm was sampled from start to finish by the armada (and The Weather Channel).

Once the tornado dissipated, the armada tried to reposition themselves to try and observe any additional tornadoes that might develop.  This proved a difficult task due to the poor road network and storm motion.  Fortunately for the armada, the storm did not produce an additional tornado, so they didn’t miss one due to poor roads.

When operations where finally called off, the armada had a long drive back to their hotel (Kearney, NE).  To make matters worse, the storms they had been targetting all day had grown together and formed what is known as a Mesoscale Convective System (MCS; really just a really big cluster of thunderstorms interacting and aiding one another).  This MCS repeatedly had transient rotational signatures, extremely large hail, and damaging winds that tracked all along the roads the armada needed to travel in order to reach their hotel.  Because of this, I kept the VORTEX II Operations Center open until after 1 AM CDT.  I’m happy to report that every vehicle made it back safely…except probes 1 and 3 which were forced to stay in Cheyenne for repairs.

The tornado was preliminarily rated an EF-1 on the Enhanced Fujita scale.  For more information, including pictures of the tornado, please visit the NWS Weather Forecast Office in Cheyenne, WY

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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!

This morning I got out of bed a little before 7 AM and headed into the National Weather Center to prepare the initial weather briefing for VORTEX II.  To me this was simply a formality as I’ve been preparing and giving weather briefings to a handful of VORTEX II participants for two weeks now, but to the roughly 100+ scientists affiliated with this project this was the beginning – the beginning of the “great tornado hunt”.  As I looked through this morning’s numerical weather prediction models, I realized that there was hardly any chance for severe thunderstorms and tornadoes across the VORTEX II domain so at 9 AM I gave the bad news to the rest of the scientists – based on the forecast, there was no chance of capturing a tornado.  Based on this forecast, the V2 steering committee decided to call a “maintenance day” which meant no operations but people should work on getting their equipment ready.

While I can’t go into specifics, it does appear that there might be a better chance of seeing severe thunderstorms and supercells tomorrow.  For the safety of the V2 crew, I can’t say where this chance of severe weather might be.  In fact, you’ll get that a lot on this blog.  The fear is that if people knew the V2 armada would be operating in their area they would be tempted to go out and either try to catch a glimpse of the armada, or worse, follow it.  This would prove detrimental to us being able to conduct our research and also pose a safety hazard if the storm change directions rapidly.  I can, however, say that the potential for tomorrow does not have a high risk of tornadoes with it, so the V2 crew might use this case as practice.  Tuesday and Wednesday actually appear to be the better days for severe weather and the armada is really gearing up for that.  Thus, even if the armada does not attempt to collect data tomorrow, there is a good chance they will leave and head toward the target area for Tuesday.

Anyways, I’m still at the VORTEX II Operations Center and am about to head home for the evening.  I’ll try to post pictures and more information about the VOC in future posts, but for now, I’m going to head home for dinner.  Most nights, I won’t have this luxury!

Feel free to post any questions you might have, and if I can, I’ll answer them.

Happy Mothers Day to all the moms and moms-to-be!

VORTEX II (Verification of the Origin of Rotation in Tornadoes EXPeriment) is scheduled to begin on 10 May and last through 13 June.  I’ll be manning the VORTEX II Operations Center (VOC) here in Norman on a daily basis.  In addition to this, I’m currently writing code (in my spare time) to generate images of model output for use by forecasters in the VOC.  All of this is on top of my current research and school work – which includes making corrections to a journal article and editing a political science paper that needs to be submittd ASAP.  This is certainly a rough end of the semester; and it only goes down hill from there.