Could Oklahoma City See Severe Weather on Thursday?

That is the age old question right now. Will Oklahoma City’s chances run out for severe weather? Thursday is starting to look more & more promising. A dryline will set up near US-81 late Thursday afternoon. If we can break the cap, due to the potent nature of this system coming in, we could be looking at an upper level severe weather outbreak for Oklahoma City. People east of US-81 in Oklahoma, Kansas & Texas need to keep an eye out on this situation. Look for more updates on this. Let’s look at the Day 3 Convective Outlook from the Storm Prediction Center to see what they say.

Day 3 convective outlook corr 1
National Weather Service Storm Prediction Center Norman OK
0336 am CDT Tuesday Apr 12 2011

Valid 141200z – 151200z

There is a slight risk of severe thunderstorms across parts of the Southern Plains…Central Plains…Ozarks and middle-MO valley…

Southern and Central Plains/Ozarks and middle-MO valley: An impressive upper-level trough with a negative tilt is forecast to move into the southern High Plains Thursday. A well-defined 70 to 90 knots middle-level jet is forecast to move through the base of the trough with the exit region spreading eastward across the Southern Plains. This feature will create strong deep layer shear profiles creating a favorable shear environment for severe storms. Ahead of the system…a strengthening low-level jet should transport moisture northward with the models developing an axis of moderate instability across eastern OK and eastern Kansas Thursday afternoon. Forecast soundings diminish a strong capping inversion around 21z with storms initiating just to the east of a dryline oriented north to south along the I-35 corridor. As storm coverage increases during the late afternoon and early evening…the environment should support supercell development especially beneath the exit region of the middle-level jet where 0-6 km shear values are forecast to be in the 50 to 60 knots range.

Forecast soundings by early evening across eastern OK…western Arkansas and southeastern Kansas show looped hodographs with 0-3 km storm relative helicities in the 400 to 450 m2/s2 range. The low-level shear should increase by early evening as the low-level jet strengthens…supporting a tornado threat with the more dominant supercell storms. In addition…moderate instability…steep middle-level lapse rates and 500 mb temperatures of -14 to -16 c should be favorable for large hail. A threat for very large hail…>= 2 inches in diameter…will also be possible with the better organized supercells. The severe threat should extend as far north as Kansas City where the NAM shows a 995 mb surface low just to the east of the upper-level low. Backed southeasterly winds ahead of the surface low and strong low-level shear should also be sufficient for a tornado threat in NE Kansas and western MO where cold temperatures aloft will also make large hail possible as well.

On the southern edge of the slight risk area about 100 statute miles south of the Red River…forecast soundings maintain a strong capping inversion through the afternoon and evening. This suggests the threat for severe storms should drop off quickly from north to south across the Ark/La/Tex. The severe threat in the Ozarks is expected to weaken during the late evening but a marginal severe threat could continue into the overnight period as an mesoscale convective system or convective cluster moves eastward into the lower to middle-MS valley.


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