Tuesday, February 10, 2009

Timing and Location

How annoying the timing and the location of certain events can be. Though some may get lucky, many southern plains chasers are learning this today with a moderate risk issued, and tornadic storms likely to develop this evening. However, most of the potentially violent weather will likely be over poor terrain, and potentially nearing dark as the sun still goes down around 5:30 at this time of the year.

We here in the Ohio Valley will get our turn with the system tonight and tomorrow morning. While the a kinematic system of this magnitude will raise some eyebrows, the timing and location of this system couldn't be worse. Earlier runs were showing a very good April-like system coming into the area on Wednesday afternoon leaving a large warm sector over chaseable central Illinois. However, the opposite of what I had hoped would happen materialized and the NAM fell more into line with the GFS and the system really sped up.

Severe weather potential remains, and will likely unfold over parts of Illinois and the Ohio Valley. However, rather than being in the mid-afternoon with plenty of destabilization we'll likely be relying more on the kinematic side of the system to realize the severe potential. When this happens, more often than not the tornado potential is minimized and strong wind gusts rule the day. While some significant wind damage is a good possibility, it isn't exactly the cat's meow when it comes to chasing eye candy.

Then we have the location. I love high winds. I love nothing more (okay, I love a few things more) than to park it in front of a significant wind damage producing bow echo and watch everything get blown over. Given the time of the year, after a long winter I'll often take this over nothing. But again, the location is also screwy with this system. Rather than that nice fat warm sector over flat central Illinois, the prime area will likely be pushed a bit further south. The models currently have the warm front swinging as far north as Interstate 74 by 9 am. With such a high qpf forecast on the north side of the warm front I'm weary of buying into such a northward swing. This means that the prime area for severe weather will more or less ride right along the jungle that follows the Ohio River. Tornadic storms are possible in Tennessee and Kentucky, some of which is chaseable terrain but for this system I will not make such a journey.

All whining aside, should we really see such a northward push with the dry slot and warm sector tomorrow morning we may see decent severe weather possibilities in parts of central Illinois. I will be watching the Interstate 70 corridor from St. Louis, across south central Illinois towards Indianapolis. We'll likely see a large area of thunderstorms and rain develop around the Ohio River tonight, with the severe squall line forming in Arkansas at the same time. Severe storms will likely spread into southern Missouri later in the night with a northward push of the other convective area near the Ohio River, lifting the rain and thunderstorms into central Illinois. Towards sunrise, severe thunderstorms, potentially tornadic should be ongoing from St. Louis southward into Arkansas, to near Memphis. A couple strong overnight tornadoes are possible across that line and west overnight. Should the warm sector surge north fast enough, we may see a continuation of the severe area of thunderstorms across the southern half of Illinois, Kentucky and Tennessee and then parts to the east in Indiana towards noon. Again, should the warm sector clear out fast enough, I would not rule out a couple tornado reports from 6 AM to 1 PM from St. Louis to Indianapolis along Interstate 70. The more likely scenario will however be primarily wind damage.

With such a complicated scenario, it's best to ask me what I really think 24 hours from now.

Instead of chasing in Oklahoma, I'll likely spend the rest of today finishing getting the car ready for that epic first chase of the year. Should that first chase take place tomorrow morning, we shall see.


Unknown said...

I'm with you on the time of day factor being unfavorable. Around the time of passage i'll be either getting off work or near to it. Might be too close to get to a decent location SE of Decatur in time but who knows. Good luck to you in whatever you end up doing. p

Andrew Pritchard said...

I never really buy into the 18Z model runs, but if you do this time they've slowed the system down a little bit.