Severe Weather Today: 5/14/15

The Storm Prediction Center (SPC) has issued a Slight Risk for severe weather today over western Texas.

Associated with the Slight Risk is a 2% Tornado Threat Ring.

The visible satellite image over the threat area today is interesting. At first glance, you see a light cirrus blanket over the whole region. But, under closer inspection, there is a lower cloud deck. This lower deck has a few cumulus fields, most notably near my old friend, Fort Stockton, TX. In fact, under really close inspection, you can see a light boundary that stretches from Oklahoma City, OK, to Chillicothe, TX to approximately Fort Stockton, TX. There is also a faint boundary that extends southwest from southeastern Oklahoma, just north of the Dallas/Fort Worth Metro area, into this other boundary.

The enhanced infrared imagery shows that some of the clouds are quite thick in the threat area. However, notice how the bands of thicker clouds are oriented northwest to southeast.

The 12Z upper air sounding near Midland/Odessa, TX is not very impressive. There is a little Convective Available Potential Energy (CAPE), but there is also a large capping inversion in place. The surface was relatively damp, with a dewpoint depression of only 3 F (65 F surface temperature – a dewpoint of 62 F), but then there is a thick, extremely dry layer above 850 mb.

The deep-layer shear is not impressive (24 kts), but the low-level shear is great (30 kts). Southerly winds at the surface, shifting west as we climb higher into the atmosphere.

The SPC Mesoscale Analysis surface observations chart shows southern or southeasterly winds across most of Texas. There are a few smaller anomalies worth examining, however. Near Dallas, and up in the Panhandle Region, winds are from the southwest. This would normally bring drier air into the region. This is the case in the Panhandle, as dewpoints are only in the 50s here. However, the Dallas area still has dewpoints in the low 70s, as even the “drier” air has dewpoints in the upper 60s or lower 70s.

More importantly, there is a visible dryline that extends through west Texas from just east of Fort Stockton, TX, to just east of Childress, TX, and then it juts east through Oklahoma, passing just east of Woodward, OK. In some places, the moisture gradient is quite large; the dewpoint drops from 66F to 57F as you travel north in western Oklahoma. This dryline marks the western edge of our cumulus field that is present on the visible satellite imagery.

The Normalized CAPE chart shows an axis of stronger values from the Big Bend Region to Andrews County, TX. However, I am also intrigued by the region east of Childress, TX. That area coincided with the sharpest dewpoint boundary as well.

The effective bulk shear is unimpressive all over the state of Texas. The best we may get is if the shear maxima over northern Mexico trains northeast into the Big Bend region.

I threw the supercell composite chart on here, just for fun. I should point out that the supercell composite is 0.5 just west of my house here in Rio Rancho, NM. I’ll have to keep an eye on this as well. Overall, it is not impressive anywhere in Texas, due to the low shear.

If I were chasing today, I would make the best of it. I don’t see a huge potential for rotating storms, given the low shear. I was drawn north towards Childress, but the shear is so low there, and likely won’t increase enough to support severe storms. However, farther south, there is increasing shear as the trough pushes east. This area is heavily capped though, and I’m not optimistic about it either. Chances are, I would hang out somewhere between Post, TX; Snyder, TX; and Clairemont, TX; enjoy the smell of oil from the Permian Basin, and wait for a subtle change in shear. I think going farther south is just going to put me into a more heavily-capped region.

Thank you for reading my prediction.

The Severe Weather Outlook is from the Storm Prediction Center website.
The satellite imagery is from the NOAA Satellite and Information Service.
The surface observation and upper level charts are from Unisys Weather.

About highplainschasing

This blog is about my tales in storm chasing. My name is Seth Price and I am an instrumentation instructor at New Mexico Tech. My amateur radio call sign is N3MRA.
This entry was posted in Practicing Concepts, Predictions, Satellite Imagery and tagged , , , , , , , . Bookmark the permalink.

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