Extended Forecast

052117 Extended Forecast Map

Welp, time to start looking ahead to our next chance for tornadoes. Still a long ways out and the GFS has been very inconsistent with the placement and extent of any severe weather/tornado threat for Friday, so take the above map with a huge grain of salt. As a matter of fact I based that map off guidance from the 00z and 06Z runs of the GFS. As I type this the 12Z run just came out and it has shifted the threat area south with mid level flow being too weak for supercells over the northern portion of the threat area on the above map.

Good quality moisture has already been pushed into southern Texas. Although there will be some modest return flow of moisture into the southern plains tomorrow, moisture quality will not be good enough for a tornado threat. Things will remain quiet through the week as a trough dives south over the plains and northerly winds keep quality moisture over the Gulf of Mexico. As the trough pushes east around the middle of the week, SW flow aloft will setup a lee side low and moisture should start advecting back north into the plains on Thursday. There is some chance for severe weather on Thursday along a dryline, but for now my guess is moisture quality won’t be quite good enough yet for a meaningful tornado threat. It’s something to watch though. By Friday better quality moisture should be in the plains with dewpoints in the upper 60’s/low 70’s being forecast. The focus for severe storms and tornadoes would be a surface low in the central plains and a dryline running south from there. There is not a strong trough with this setup. It will be modest southwest flow with small waves working through it. This makes it difficult to judge the exact location and extent of any threat, especially this far out. That being said, it’s kind of pointless getting into any details about what the GFS is showing. It has jumped around a lot over the last 4 runs, with the latest run keeping stronger mid level winds/favorable deep layer shear farther south in Oklahoma. I’ll be keeping an eye on it and update regularly. My guess is that Friday will be our next chase day. With good quality moisture and strong instability in place, it won’t take a whole lot in the way of shear to support a tornado threat. One thing I do like about these types of SW flow/low amplitude disturbance type setups is that there is little forcing, so you’re likely to get discrete storms and directional shear can be really good. I am a huge fan of both. Anyway, I’m watching each model run so I’ll be going over this setup as it evolves at least once or twice a day, so check back for updates if you’re interested.

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