Tuesday, May 10, 2011

Update on Wednesday's Severe Weather Potential

Several rounds of severe weather, some potentially significant, appear likely for Wednesday.  The situation is a bit more complex than "normal".  The goal of this post is to clarify how the situation is most likely to unfold, at least as we understand things at this time...

The first image below is the latest severe weather outlook from the SPC in Norman, OK, valid for Wednesday & Wednesday Night.  In general, severe thunderstorms are possible anywhere within the areas outlined in yellow.  An "enhanced" threat of severe weather (i.e., more widespread and potentially more significant) exists within the area outlined in red:

Large hail, damaging winds and isolated tornadoes are possible with any severe thunderstorms that form on Wednesday, into Wednesday night.

An enhanced risk of very large hail, damaging winds and possibly stronger and/or long track tornadoes exists within the black hatched area on the image below.  This enhanced risk is particularly high over the areas in purple, from portions of central & western Kansas into western Oklahoma:

At this time, it appears that organized severe thunderstorm development will take place in 3 primary "waves" on Wednesday, as noted by the image below:

The earliest potential for severe thunderstorm development is expected to take place from late morning to early afternoon across portions of central and southern Texas.  Large hail & damaging winds will be the primary threat in this region, although isolated tornadoes also cannot be ruled out.  This development will take place in association with an upper-level weather disturbance that is forecast to move out over the region ahead of the surface dryline.

The next wave of severe weather is expected to begin by midday or early afternoon across portions of central and northwest Kansas, along and ahead of the dryline and an even stronger upper-level weather disturbance.  Large hail, damaging winds and tornadoes will all be possible with this activity.

A third region of organized severe thunderstorm development is expected to extend from southern Kansas into much of central Oklahoma, along and ahead of the dryline and upper-level weather disturbance.  This activity is likely to form by mid to late afternoon, or during the more "traditional" time that you would expect severe weather to form.  The coincidence of the strongest low-level moisture & instability, stronger middle & upper level winds and energy all suggest that severe weather in this region may be particularly strong.  This would include the potential for very large hail, damaging winds and tornadoes, some of which could be strong and/or long-tracked.

Severe thunderstorm activity would initially develop along the Western border areas of each of the above regions, then spread East/Northeastward over time.

Residents throughout the severe weather outlook areas should pay very close attention to the weather on Wednesday.  Keep in mind that the above scenarios are based on the most current data available and could change.  Listen for later statements & forecasts and be prepared to seek shelter if threatening weather approaches or a warning is issued for your area.

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