FCST: Thursday April 6th
Active early spring pattern continues with another powerful system coming into the plains on Thursday. Main concerns for chasing at this point are moisture quality and instability, along with very fast storm motions. As we saw on March 12th (a day I was under 2 separate mesos), in these situations you typically have one chance at a storm as it passes. Exactly where you decide to do your "toro!" is key...you really want to see the storm at peak intensity. In the case of the second storm I was on March 12th, had I chose my spot one county to the NE, I would have seen a strong tornado.
Models are in good agreement as far as timing of this trough, and the new 00Z 4/4 NAM has changed for the better it would seem. The trough over the E is not as far south, which will help moisture return a tad. And, the dryline is farther W than previously progged, now over ERN KS/OK at 00Z Friday instead of way far E into wrn MO. NAM is still holding near 60 surface dewpoints all the way up into Nebraska and SWRN IA, which when combined with very cold temps aloft creates some decent instability with MLCAPE of around 1800 according to forecast soundings. Keep in mine moisture "depth" may not be great, and if it mixes out, which it probably will, we will be left with upper 50s dewpoints. However, that's no different than March 12th and you know what happened that day. The key is keeping steep low to mid level lapse rates, for example 700-500 mb. I like to say, "Lapse rates over 8, tornadoes will be great", referring to 7-5 lapse rates over 8 c/km. Anyhow, I will likely chase Thursday.
Models are in good agreement as far as timing of this trough, and the new 00Z 4/4 NAM has changed for the better it would seem. The trough over the E is not as far south, which will help moisture return a tad. And, the dryline is farther W than previously progged, now over ERN KS/OK at 00Z Friday instead of way far E into wrn MO. NAM is still holding near 60 surface dewpoints all the way up into Nebraska and SWRN IA, which when combined with very cold temps aloft creates some decent instability with MLCAPE of around 1800 according to forecast soundings. Keep in mine moisture "depth" may not be great, and if it mixes out, which it probably will, we will be left with upper 50s dewpoints. However, that's no different than March 12th and you know what happened that day. The key is keeping steep low to mid level lapse rates, for example 700-500 mb. I like to say, "Lapse rates over 8, tornadoes will be great", referring to 7-5 lapse rates over 8 c/km. Anyhow, I will likely chase Thursday.
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