LP (Updraft dominate) High Based Cells Northeastern Permian Basin, April 26, 2008

A return of Low Level Moisture proceeding the arrival of Upper Level dynamic Forcing, east of the dry-line, allowed for severe weather potential and the Central and Eastern Permian Basin were included in a slight category by the SPC. A developing Theta-E Ridge trending southeast to northwest due to warm moist air advecting from the Gulf was established by 1800Z. During the next several hours drier air was filtering into the Central Permian Basin where dew points had dropped into the high 30's to low 40's. A decision was made to target the Eastern Permian Basin as Cumulus development was beginning to occur by 2230Z in Sterling County, where low level moisture was still potent. The 500MB winds were generally trending west to east and the 300MB winds a little north of west to east. Steep lower and mid layer lapse rates were noted and Lifted Indices were greater than -5 (SB CAPE between 1500-2000 J/kG) which suggested rapid storm tower convection once initiated. The first image is of a developing Storm Tower(s) complex as viewed from west looking east on SH 158, 3 miles east of intersection SH 137 at 2330Z in Glasscock County (Towers are in Sterling County). A decision was made after arriving in Garden City to take FM 33 north to Big Spring and target the quickly convecting Storm Towers and developing LP Supercell occurring in eastern Howard County as shown from the next image approximately 8 miles north of Garden City looking north-northeast at 0000Z. The next image was taken at the intersection of FM 461 and SH 87, near Forsan in southeast Howard County at 0010Z, looking northnorth-east. The next image is while driving north on FM 821 in eastern Howard County, looking NNE, noting the crispness, scalloped grooves, of southern tower as it convects upward toward the Equilibrium Level. The next image is a zoom of the previous. The author continued north on FM 821 until intersecting Interstate 20 and then proceeded east capturing the next image, at 0030Z, of the updraft intake area (slightly lowered Wall Cloud), center, an attached small "Beavers Tail" inflow band attached to Shelf Cloud, right, and an associated hail shaft, left, that had begun to fall from this LP cell. Storm movement is slightly south of parallel to Interstate, away from camera. The complex appeared to be back-building with newer convection occurring west of previous. The next image is a closer viewed portion of the updraft region and RFD notching. The next photograph is taken from Interstate 20 near the Howard and Mitchell County boundary, looking southeast, beneath Rain Free Base of current chased storm toward a distant spreading Anvil from earlier convection in Coke and Sterling counties,background, and new convecting storm towers, foreground. Hail, generally nickel size but some quarter size was encounter-ed near Westbrook, Mitchell County, at 0100Z. The authored traveled to Colorado City, remaining in hail, and turned south on SH 208 to "punch the core" of a another backbuilding complex which was moving southeast. Approximately 6-8 miles south of said State Highway intense hail was encountered, generally nickel size but some larger but falling very densely. The next image(s), approximately at 0110Z to 0130Z, is of hailstone covered State Highway south of Colorado City in Mitchell County.

The first image from a video still, below, is of accumulation of nickel and quarter size hail forming levees between channelized rushing water runoff on SH 208. The next image also from a video still is looking south while driving on lithified hailstone ice. The last image is at 0130Z looking at hail accumulation on SH 208 and adjoining farm furrowed fields approximately 10 miles south-southeast of Colorado City, Mitchell County.

High Based LP Cell Northwestern Dawson County, Texas, April 23, 2008

The following images are of a High Based LP Cell taken several hours later from the earlier described,( previous Blog-below), Low Based Circulation Storm. The images were taken along Ranch Rd 829 several miles south of the SH 180 intersection, looking to the NNW at initiation along a west to east trending warm front and a north to south trending dry-line. The first image, above, is capturing a spreading Anvil canopy above a high based Rain Free Base and aslo denoting the Rear Flanking Line with a small Roll Cloud beneath at lower left. The second image is looking west at the developing Rear Flanking Line obscuring the sun. Note the tapering Roll Cloud beneath. The final two images are taken as the LP Cell with attendant Roll Cloud slowly advanced to the eastsoutheast.

Low Level SuperCell Circulation, Martin County, Texas, April 23, 2008

The above two images were taken from a developing Supercell in southeastern Gaines/northwestern Martin County(s) at approximately 2240Z while positioned at the Seminole Pipeline Compressor (Patricia Station) along SH 349, 25 miles north of Midland, as viewed from south looking northwest. A ragged updraft region is noted with associated scud clouds. The third image is a capture of a well defined crisp wall cloud beneath the Rear Flanking Line (but tilted to main storm tower) and left of a RFD incisement with noted dust blowing from northeast to southwest at lower left. The fourth image captures the advancing RFD incising into updraft intake area and a small tail cloud at far right. The remaining images below are taken a short time later, approx-imately 2315Z on Ranch Rd 829 in north central Martin County looking to the southeast from behind the RFD and Clear Slot, viewing low level rotation with associated Scud clouds. Note on second to last image the strong RFD winds blowing sand across road. The final image is of a very low circulation center and Wall Cloud with rainbow on the left of image and Rear Flanking Line on right of image, as viewed from behind the RFD region. This Supercell was tornado warned by NWS/MAF with Doppler Radar.

Permian Basin Severe Weather, April 9th, 2008

The synoptic events leading to eventual severe weather, abruptly initiated approximately at 0230Z , west of Odessa and trending north-south along the rejuvenated dryline was an interesting scenario to witness. During the afternoon, between 1900-2200Z, high base (roots around the 850MB layer) convection produced storm towers proximal to a slowly northward advancing surface warm front due to an increasing LLJ advecting moist Gulf air from the southeast overriding cooler entrenched continental polar air. Locally within the Central and Eastern Permian Basin, this convection was concentrated in Reagan, Glasscock, and Sterling counties and movement was to the northeast. During this time frame, dry surface air had already passed east of Midland from the advancing dry-line (2M dew points had fallen from the high 50's to around 30 degrees). The first image is of a convecting storm tower (updraft dominated and first indication of lowering of convective condensation level) captured along SH 158, three miles east of intersection SH 137, in Glasscock county at 2105Z, looking southwest. The second image is of the sheared, northeast trending, canopy storm tower of previously captured developing cell with small underlying Mammatus clouds as viewed from observer's vantage point directly overhead, demonstrating strong upper level winds. The third image is a zoomed capture of updraft intake region.





My thoughts at the time was that further develop-ment and intensifi-cation was probable along said warm front boundary and to the north but east of advancing dry-line which had already traversed Midland. I had to return to Midland and could not await further initiation at current locale or proceed further east, being somewhat disappointed in not witnessing a Supercell. Driving back to Midland I was expecting to encounter crisp dry blue skies but instead noted hazy conditions indicating a return of moisture. I drove to a multi-storied parking garage and captured the next image looking east at continued cumulus accretion and developing cumulonimbus. The wind had changed direction from previous southwest to now northerly, the dry-line was retreating and convection was firing near this Triple Point (advancing cold air from north, and well tuned slightly retreating north-south trending demarcation between moist warm air, east and dry air,west). An amplified Upper Level Trough with wind maxima, cold air aloft, and height falls was continuing to advance from west to east and intensifying surface cyclogensis, currently responsible for halting the warm front's advance and advecting cooler air south, was shortly progged to reestablish a returned progressive eastward surge of the well defined dry-moist boundary. The timing of the dry-line eastern surge coupled with the Upper Level support and the locale of the Triple Point, separating unstable from stable air mass surface boundary(s), was not immediately known but became readily apparent at approximately 0230Z west of Odessa. The final image is from MAF WSR-88D radar taken at 0304Z as the advancing squall line composed of intense multicelled storm towers, firing along a bulging dryline and centered over Midland. Note from radar capture the strongly northeast sheared echos ahead of the advancing squall line ( mini Derecho, bowing, with associated strong straight line winds). At the author's residence, near downtown Midland, marble size hail was encountered. Rainfall rates were estimated at around 2"/hour during the brief intense deluge which lasted approximately 20 minutes. Intense cloud to cloud and cloud to ground lightning was noted and wind gust were estimated at approximately 35-45mph. The squall line was advancing at a rate of approximately 45mph. Channel 9 meteorologist, Tom Tefertiller, indicated from VIPIR software that tennis-ball size hail was probable at certain locales along the multi-celled complex based on VIL profiles.

Severe Weather Threat for Wednesday April 9th, 2008

The 1200Z Wednesday MAF Skew T is very impressive and demonstrates the deepening moisture return from an intensifying Low Level Jet. The sheared wind profile is very supportive of rotating storms which may initiate near an advancing dryline suggested from the RUC to be proximal to the central Permian Basin by 0Z Thursday (7pm Wednesday local). Refer to the projected position of the 2M dew point at 0Z Thursday accompanied by the 500 MB speed of right exit region around intensifying Upper Level Trough at same time (0Z).

Severe Weather Possibe Late Wednesday early Thursday, 9th and 10th, 2008

The WRF model indicates Severe Weather is a possiblility for the Central and Eastern Permian Basin beggininng late Wednesday and culminating at maximum potential around 0600Z Thursday when interaction between intensifying Upper Level Trough with associated "right exit region" embedded short waves converge over 850MB Theta E Ridge from enhanced LLJ. The GFS solution is a little faster in timing than WRF which could increase severe threat if aided by solar insolation. At left, is the WRF 500 MB wind speed predicted at 0600Z Thursday followed by the 850 MB Theta E. The finale image is MLCAPE values as predicted by WRF at 0600Z Thursday.