SEVERE WEATHER ACROSS SOUTHERN PLAINS (5/23/2011)

The weather pattern hasn’t really changed much over the past couple of days in the Southern and Central Plains region.  A rather stationary frontal boundary, along with a dryline, has prevailed over this area, which has been the main culprit for the severe weather in Oklahoma, Kansas and Missouri past few days.  Pretty much the entire Southern Plains is under the gun for severe weather today, again.  Best chance for severe weather will depend on the location of the dryline and diurnal heating.  Surface-based (SB) CAPE (shown below) values are pretty impressive, especially in northwestern Texas and north-central Oklahoma.

Figure 1. 17Z 5/23 SPC analysis of SBCAPE (contoured), energy to fuel storms. Shaded is SBCIN

Because one factor cannot be looked at when forecasting severe weather, we’ll take a look at bulk shear (sfc-6km) values.  Along with CAPE, wind shear is important in keeping the structure of a storm alive.  As the heating of the day continues, temperature and pressure gradients will tighten, that will produce stronger shear for these storms.  At 17Z, the strongest shear values from surface to 6km look to be in northeastern Oklahoma/northwestern Arkansas.  Again, shear values will likely get stronger as the heating of the day continues.

Figure 2. Wind shear values (sfc-6km) at 17Z 5/23/2011.

Something to look for at the surface would be dewpoint temperatures.  Thunderstorms usually generate off of higher dewpoints.  Also, looking at dewpoints gives you an idea of where the dryline is located, if applicable.  If enough lift, moisture, and energy are present, thunderstorms will fire along or just east of the dryline.  Figure 3, below, contours the air temperatures in red/purple, shades the dewpoint temperatures in green and aqua blue, and contours the surface pressure in solid black.  Notice where the dryline is currently (18Z) located, western Oklahoma/central Kansas.  Since drylines move eastward during the day, this dryline will probably do the same as the day continues.

Figure 3. SPC Surface map showing temperature, dewpoints, and surface pressure.

Based on just these three things (SBCAPE, Shear, Dewpoint), I would say northwest Texas, western/central/north-central Oklahoma, and central/south-central Kansas will experience the worst of the severe weather today in the Southern Plains.  This is not to say that other areas in the Southern Plains won’t.  Of course, there are many, many more things we could look at, but these 3 will do for now.  Northern Arkansas as well as much of Missouri are still in a threat for severe weather that includes significant hail, gusty winds, and isolated tornadoes.

HPC Surface Analysis 15Z 110523

Figure 4. HPC surface analysis at 15Z. Frontal boundary has been oscillating back and forth over the past few days, causing severe storms in Texas, Oklahoma, Kansas, Missouri, Arkansas, Iowa, Nebraska, Minnesota, Wisconsin, Illinois, and many more states

About Brian

University of Oklahoma graduate with a degree in Meteorology. Follow me on Twitter: @WeatherInformer
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