Sunday Severe Threat - Oklahoma Skies
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April 23, 2016 2:11PM CDT

While everyone is talking about Tuesday(not that it isn't warranted) I've been keeping close tabs on tomorrow(Sunday) as well. While synoptically not "as" impressive as a setup as Tuesday, a passing short wave and favorable thermodynamic environment will promote the risk for severe storms mainly late Sunday afternoon through the evening hours. 

The latest day two outlook from the Storm Prediction Center(SPC) highlights a large swath of the central and southern plains in a slight risk(level 2/5) for severe weather Sunday. The latest trend has been to expand the higher severe probabilities a little farther southwest into more of northern Oklahoma as latest high resolution models are fairly aggressive in QPF development along the dryline tomorrow evening. 

Strong south/southeasterly low level winds will lead to a fairly rapid return of deep gulf moisture ahead of a sharpening dryline across western Oklahoma late Sunday afternoon. This process is already underway with south winds coming up and dews have been slowly but surely rising. 

If you are planning on participating in the memorial marathon in downtown OKC tomorrow the weather shouldn't give you any problems. Just a bit windy and warm. 

The 4KM NAM depicts surface dewpoints in the mid 60s as moisture pools ahead of the dryline Sunday evening. 

With the increasing moisture and warm temperatures, surface based instability should become elevated by peak heating. SBCAPE values approaching 3000j/kg will be more than sufficient to promote vigorous updraft growth. 

Later in the evening low level winds will really ramp up with the nocturnal increase of the low level jet. This will create favorable low level shear for rotating low level mesocyclones with any supercells that can persist and overcome boundary layer stabilization/decoupling with the loss of daytime heating. The tornado threat with storms tomorrow will be highest during the 7-10pm time frame across northern Oklahoma tomorrow with any supercells that are still present. Perhaps the biggest inhibiting factor for a more robust tornado threat will be the uncertainty regarding surface based moisture. If we get the dews that the 4KM NAM is depicting above then watch out. I feel the 4KM NAM may be slightly overdoing moisture quality, especially looking at current observations across south Texas with mid 50 dews still all the way down across the Rio Grande valley and far south Texas. However the mesoanalysis surface obs page is going to get a good workout tomorrow by chasers and meteorologists alike. Time will tell. 

This graphic shows the 4KM NAM simulated composite reflectivity for around 7pm CDT tomorrow evening. It's fairly aggressive with convective development along the dryline. I'm not sure just how much coverage of storms there will be(especially south of I-40) tomorrow considering there will be a pretty stout CAP in place and the better forcing for ascent will be across far northern Oklahoma and Kansas closer to the upper level system. However, any storms that do develop tomorrow will be capable of substantial severe weather including very large hail, damaging winds, and even tornadoes. Will likely be chasing somewhere over northwestern or northern Oklahoma tomorrow. 

Tuesday still looks like a big day for severe storms for N TX/OK/KS. Lots of variability in the models though and I refuse to get too specific until we get a little closer. My best advice is to stay abreast of the latest forecasts and make sure you are prepared for the possibility of severe storms. Stay tuned. 

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