Severe Storms Possible Thursday.


Tuesday, April 12th 2011, 3:07 pm
By: News On 6


Alan spent a great deal of time in his morning discussion going over some of the parameters that could produce severe storms in E OK this coming Thursday. Thought a graphical depiction would also help to explain why what does happen will be confined to the eastern part of the state.

The map on the right shows surface features related to the wind and moisture fields at 7 PM Thursday. In this case, the colors represent dew point temperature which is a measure of how much moisture is available. A very sharp E-W gradient in moisture is clearly depicted along and just east of I-35.

The other depicted variable is what is referred to as streamlines which shows the wind field. That clearly shows why there is such a sharp gradient in moisture as a westerly wind component is co-located with the drier air and a southerly wind component is co-located with the moisture. Some moisture in W Kansas and far NW Ok has wrapped around the main surface low which is located in Nebraska at the map time. Clearly, the greater surface moisture extends from E Neb southward across E Ok and into Tx. That is also where the greater instability will exist.

This is a very clear depiction of the forecast position of the dry line and as was the case this past Sunday, storms are expected to be developing along and ahead of that feature and quickly move on eastward. There are also some significant differences between this situation and this past Sunday, not the least of which is the orientation of the streamlines. Last Sunday, the winds gradually veered from S to SW to W minimizing the convergence along the dry line. If this forecast verifies, the change in wind direction is much sharper which will result in greater convergence; therefore more widespread thunderstorm activity.

Obviously, there are also some limiting factors or we would go with a higher rain chance. Bottom line is that storms in E Ok are going to be a good bet for late Thursday and some will likely be severe.

In the meantime, light winds and sunny skies have produced the nicest day in awhile for us today. Not for long though as gusty southerly winds will be kicking back up again on Wed creating another very high fire danger situation. Temperatures will remain well above normal this afternoon and again Wed afternoon. Thursday will also be quite warm, but once those storms move through much cooler air will follow for Friday and to start the coming weekend.

Preliminary data also suggests another system early next week with a decent shot at rain/storms. In fact, a more active pattern appears likely for much of that following week so perhaps we will eventually get a good, soaking rain. Not going to get your hopes up too much just yet, but it does appear like a more active pattern over the next two weeks.

As always, stay tuned and check back for updates.

Dick Faurot