Wednesday Severe Potential
Models have come into pretty good agreement on Wednesday. As a shortwave swings east from the Pacific Northwest into some modest ridging over the Mississippi Valley, the stage is set for severe weather.
By Wednesday afternoon, the models show a surface low developing over the west-central Plains. While the moisture influx has come into question, the GFS continues to advect 60F dew-points all the way to portions of Nebraska. The Euro has been fairly steady with dew-points in the upper 50s to lower 60s, while the NAM is somewhat less impressive. Kinematic support is essentially a given with a low-level jet increasing to 40-60kt at 850mb by late afternoon and early evening. Instability and more-so capping were bigger question marks. There is strong support for a corridor of moderate instability from north Texas up into central Kansas ahead of the surface low. SBCAPE is progged in at around 2000 J/kg over much of the area. The GFS has been inconsistent in terms of how much of the cap can be eroded before maximum heating is lost. Again, the NAM is slightly less impressive and the GFS is the most bullish of the latest model guidance.
The focus for isolated supercells will largely be just ahead of a dryline. The parameters would suggest a threat for very large hail and damaging winds from far northwest Texas into western Oklahoma, much of Kansas and perhaps extending into adjacent Nebraska and Iowa. While tornadoes are also possible, it’s a bit too soon to say how widespread or intense that threat could be. It will likely come down to just how much of a moisture influx is realized into Kansas and points north. At the moment, trends favor less in the way of a tornado potential.
A fair analog is May 17th, 2005. The setup then was similar, albeit a few hundred miles further north, to what is expected this Wednesday. The only other notable difference was dew-points in the lower 60s. This time around, it would appear that realistically, dews will be in the range of the upper 50s to around 60. Nonetheless, the similarities make it a good match. Then, there were 62 hail reports, 11 wind reports and 3 reports of tornadoes. The focus was over Nebraska into South Dakota for most of the severe weather. Due to the further south track expected for Wednesday, that would translate into the Kansas/Nebraska area this time around.
While some activity is possible on Thursday, the greatest severe threat targets Wednesday. There could be a continued active pattern to close out April as a deeper trough is modeled to dig into the West Coast by this upcoming weekend.
Stay tuned for more information later Monday into Tuesday.
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