Friday, March 30, 2012

Severe Thunderstorms Possible Southern Plains; OH Valley/Midwest Today...

Severe thunderstorms are forecast within two areas today, as noted in yellow on the above image.

The first, and at least initially the most pronounced, is likely to be over portions of the Midwest and Ohio valley region.  A moist, unstable airmass is in place and will interact with an upper-level weather disturbance to initiate thunderstorm development by mid to late afternoon, likely near the Western edge of the severe weather outlook area initially.

Once developed, this activity will move and/or develop to the East over the Ohio Valley region into this evening.

Large hail and damaging winds are the primary threats in this region, however a few tornadoes cannot be ruled out with any particularly well organized, and especially isolated, storms.

Further West and Southwest, a "conditional" risk of severe weather exists over portions of the southern Plains for late this afternoon into this evening.  The atmosphere over this region will become very unstable by this afternoon, along and South of a weak boundary along the Kansas/Oklahoma border, and along and East of a surface dryline.

The most likely form of severe weather in this region will be the potential for very large (2 inch diameter or greater) hail, as shown by the yellow shaded and black hatched area on the image below:

I point out that the risk of severe weather is "conditional" for two reasons:  (1).  the atmosphere over much of this region, especially in southern Oklahoma and Texas, is "capped" and (2).  while there will be at least some weak upper-level support to help break the cap, the timing and exact location of that support is in question at this time.

If thunderstorms are able to form in this region, they will likely become severe.  The most likely time for this to take place would be late this afternoon into this evening.  I will continue to monitor incoming data and will provide an update on the Southern Plains as the situation becomes more clear during the day today...

If you live in either of the severe weather threat areas for today, please remain on the alert.  Review your severe weather safety tips and be sure to identify the best sheltering option for you and your family at home, work or school.

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