Permian Basin First Dryline Initiation Thunderstorm(s) of Year 2008

During the early morning hours of March 17th low level moisture continued to advect into the Permian Basin via a strong LLJ in advance of a deeply amplified positively tilted Upper Level Trough associated with a Closed Upper Level Low centered in southern Arizona and northern Sonora Mexico. Below is a the RUC model 500 MB wind screen capture as of 1200Z March 17th. As the author drove to work it was apparent that bountiful Gulf mositure had returned to the Permian Basin overnight and throughout the early morning as the outside lower atmosphere was very hazy (2M dewpoints of 60 degrees very near the

2M air temperature of 63 degrees). The wind had blown steadily at sustained rates of 25-30 mph with gust to 35 mph from the south and southeast advecting moisture transport northward (see the moisture transport image from the 850 MB Theta E, 0900Z, below). Also note the difference in atmospheric moisture content between the 00Z March 17th MAF Skew T diagram with respect to the 1200Z March 17th. Once arriving at work in downtown Midland at 1200 Z, the author

noted a low level clearing approaching from the southwest to northeast indicating that the dryline was nearing and soon any convection initiation would be drawing to a close for the Central Permian Basin (see 2M dewpoint at 0300Z/ 17th) . Below from the SPC, is a 850 MB analysis (1200Z) denoting the advancing dryline at lower levels and a 500 MB (1200Z) denoting the strong mid level winds associated with right exit maxima region around strong Upper Level Cold Core Low. Although wind profiles demonstrated strong speed shear, directional shear from 0-6km was not that impressive thus limiting any storm development along dryline forcing from significantly rotating. Below, are SBCAPE values from the SPC at 1200Z. Also included is a synoptic surface map at 1230Z showing surface low(s) and associated dryline and a Theta E streamline (College of Dupage) in western Permian Basin. The last following images are from MAF NWS WSR-88 Doppler Radar of developing convection along advancing dryline beginning with capture at 1230Z followed by 1242Z, 1252Z, and 1302Z. Looking from an office building in Midland toward the east at 1330Z, one could see strong northeastward shearing (65-70 knots at mid-level) of convectiving cumulus clouds parrallel with the advancing dryline. The convective cumulus small towers were rapdily advancing southeast by northeast away from the Permian Basin and never approached severe limits. By 1300Z the surface dewpoint had dropped to 30 degress from 60 degrees at 1200Z.

SuperCell Martin County, Howard County,Texas, April 23, 2007

The following images were captured from a quickly exploding "tail-end Charlie" Supercell apart of an equally initiated multi-celled complex which developed northeast of Midland around 2300 Z on April 23, 2007. Synoptically, the Permian Basin was a very favorable region for Supercell initiation due to 1), abundant low level moisture via a strong LLJ and 2), good upper air dynamics inclusive of cold air aloft and vorticity via an Upper Level Low ejecting shortwaves . These attributes provided high CAPE values and adequate directional and speed shear, however a very strong CINH was prohibiting convection". Once forcing overcame the "Cap", locally, strong initiation rapidly ensued. The fist image, above, was taken east of Stanton in Martin County from beneath Rain Free Base looking further northeast at FFD (southeastern facing shelf cloud) and main Rain/Hail core in left center foreground.

The next image, above, shows the incising RFD near Stanton as viewed overhead. Continuing to drive east along Interstate 20 the next image shows the RFD to the left of a developing lowering of the Updraft Intake Region near Big Spring Texas. The next image is taken just north of the townsite of Coahoma, Tx from beneath the Rain Free Base and Updraft Intake Center looking back to the southwest at the Rear Flanking Line.

Driving
north on SH 820 from Coahoma, a postion was established to view the Mesocyclone from the southwest side or from the RFD perspective whereby the following below image was captured showing aforementioned cutting into the Rain Free Base region. The next image was taken just a short time later at an apparent funnel cloud as viewed from the southwest looking northeast just to the right of the previously captured RFD.

The next image is viewed at same location, southwest side of Supercell, but looking directly overhead at Towering Storm Tower noting crispness of nimbocumulus clouds. The next image is of Fractus Scud clouds proximal to the Updraft Center and adjacent Inflow Band. The next image is taken from Old Colorado City Highway east of Coahoma looking east at maturing Supercell Storm Towers and heavy rain/hail core beneath.

The last image was captured at same locale, on Old Colorado City Hwy, looking distant northeast at lowered Wall Cloud just to the right of the road and Inflow Bands associated with the Rear Flanking Line. A tornado was witnessed by the public, near this time, at the townsite of Loriane but a survey review from MAF NWS determined that damage enountered was the result of straight line winds from the RFD.

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