Tuesday, April 29, 2008

And now we anticipate...

We are in Forth Worth tonight. Same place as last night. Today we went to the Fort Worth Stockyards and a Texas Rangers Baseball game. Not what I mind doing but not what I wanted to do. I want to chase.

This spring has been outrageous in terms of its weirdness. Dry air beyond belief, not just at the surface but through the lower half of the atmosphere. Despite strong southerly winds today across Texas, we still only have dew points in the thirties. Mid 50's are close by the coast however and we still have 40 hours of recovery time. Gives you some idea on how deep the intrusion of dryness reached into the Gulf of Mexico. In January it would be strong. Near May it is ridiculous.

But we hope to make that all go away this Thursday with a major outbreak of tornadic supercells. At least, that is what the models are calling for. Here is how it plays out:

The closed low ejects into the southern plains and at the base of that trough a 50+ knot jet pushes into the increasingly warm and moist air mass. Model forecasts are calling for mid 60 dew points to make it toward the OK/KS border. Even if this is a little overdone, it is still pretty healthy.This results in CAPE's progged well over 3000 J/kg.

The positives: Shear is out of control. There is no doubt that storms will quickly become severe and supercellular. A cold front through IA/MO/KS will intersect a dry line through central OK into TX approximately along I-35. The triple point should establish somewhere in NC OK. This is the default no-brainer place to start looking. Storms should fire down the dry line. Given strong capping, good forcing is needed but should allow for discreet supercells, each capable of producing tornadoes, and some significant. 0-1 helicities exceed 150 J/kg and 0-3 values exceed 400 J/kg!

The negatives: Moisture is on its way back and it needs to be there to create a great environment. NAM overforecasts the dews by some amount and may be over zealous with the actual values. Lower dew points mean more difficult to over come the capping inversion. Although the models do not generate precip, there are adequate indications that convective forcing should take place. Also, low-level winds are progged to back with the development of a secondary low over northwest OK. The strength of this feature in actuality will determine how good the environment becomes. Models also indicate some cirrus overcast which will limit visibility and perhaps lower the heating. These details are yet to become apparent.

This will be May 1 and it is in an area that is due for severe again. I feel it will happen. I just hope we are at the right storm at the right time and acting safely!

On Friday, despite problems with convection that may be ongoing, there is a strong signal that IL will be in for a pretty intense severe weather episode. After that, we will be close to home and will probably be home a day early.


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