HP SuperCell Evoution into Multicell "Bow Echo", Southeastern Ward and North-Central Pecos Counties, Texas, May 25, 2008

The setup for Sunday afternoon was favorable for severe convection due to abundant instability (low level moisture coupled with adequate steep mid and lower lapse rates; SBCAPE values exceeding 3500 J/kg) and adequate speed/directional shear (>30knot effective bulk shear). The only question remained in what manner would convection be initiated being that a deepening Upper Level Low had retrograded further to the west, centered in southwestern Arizona, providing southwesterly winds aloft but with less speed maxima. A potential sharpening of the dryline appeared to be the best source of lift during the afternoon and early evening hours before loss of solar insolation. The SPC placed the western, northern, central, and southern portions of the Permian Basin under a severe thunderstorm watch during the early afternoon until early evening. The author left Midland at 2045Z, targeting convection initiation along the dryline near Pecos, Texas along interstate 20. The above radar image was taken in route at 2115Z to emphasize the targeted HP SuperCell which had just been tornado warned by NWS/MAF.

At a position just to the west of Odessa the first digital image, below, was captured viewing the spreading anvil over interstate 20, looking southwest at sheared storm tower, background lower center, apart of the Rear Flanking Line. The next image is a zoom of the overhanging anvil from the same position looking directly overhead noting impressive

Mammatus cloud formations. The author continued west on interstate 20 with the intent to turn south on SH 18, south of Monahans, in order to position along the southeast side of the evolved SuperCell. It was noted as driving toward this positioning that frequent cloud to ground lightening was occuring beneath the anvil canopy. The next image is of a grass wildfire ignited by lightning near the intersection of SH 18 and RR 1776 south of Monahans at 2155Z.

The following two images are, first, a radar capture at 2200Z along RR 1776, near SH 18, showing position of author's truck with relation to storm and, second, a photograph of saucer-shaped Rain Free Base, as viewed from the northeast looking southwest.

The next image portrays a lowered wall cloud, partially obscurred by rain,beneath storm base, as storm advances toward author. The radar capture, at 2215Z showing the position of the author's truck at the intersection of RR 1219 and SW 18 just north of Grandfalls. hook .

The author had to continue southward along SH 18 due to the advancement of the main updraft core which was to the southeast. The next image is south of Grandfalls at 2300Z looking west at rain cooled moist inflow toward updraft.

The following image is capturing the southeastern side of storm base, as viewed from the east, revealing inflow band into storm base from the south.

The next image, above, was taken a short time later noting larger, south entering, inflow bands into the Rain Free Base area.

Moist cooled air continued to condense near the circulation updraft as noted on the next image, left. Rotation was suggested by noting the storm tower's updraft base, next two images, demonstrating coiled striations.

Last indication, as noted on next image below and subsequent radar capture at 2330Z, of moist inflow into this SuperCell lowered updraft intake before morphing into a squall line due to strong rear inflow jet dominance, noted on last radar capture (last image), which eventually formed a "bowed"multi-celled squall line.

But before losing its once dominate status the updraft performed the best visual presentation of a lowered Wall Cloud with small associated Tail Cloud pointing toward the precipitation core as the Updraft neared SH 18 between Grandfalls and Ft Stockton. The next image is a zoom of the previous, moments later. Another view of the Tail Cloud up close.

The last image, below, is a radar capture of the bow echo configuration noting the strong rear inflow jet notch to the northwest of the author's truck, at center of the concentric rings, where straight-line winds were estimated at 65 mph when encountered shortly thereafter.