Thunderstorm Stage(s) With Associated Wet Microburst As Viewed From Midland, Looking ENE, June 7, 2009

Attached is series of a maturing convective tower, during, 1)late stage growth , 2)collapsing downdraft, and 3)dissipation stage. During the collapsing stage a wet microburst was noted. The images were taken from Midland looking toward the east/northeast during late afternoon, Sunday. The first image depicts the late stage growth of a vertically (little associated upper level tilt) oriented updraft tower with crisp edges and indication of some mid level rotation due to helix configuration. Note the convex protruding dome centered above "helix" tower.

The next image illustrates the wet microburst, during collapsing downdraft stage as noted by inverted V shaped rain and core descending beneath prior updaft region. The image has been color enhanced in order to provide resolution to outflow processes which include Virga to the left of the microburst at contact stage. Note the convex dome has collapsed and suspended rain and hail descended.

The final image denotes the dissipation stage, after microburst event, whereby the cloud structures are less crisp and the once helix shaped tower, flattened.

Small Wet Microburst(s) Associated With High Based MultiCelled Convection, East Central Midland County, Texas, June 6th, 2009

The early evening of June 6, between approximately 2330Z through 0130Z, produced multi celled clusters in Eastern Midland and Glasscock Counties. Very steep lapse rates at low and mid levels combined with surface dew points in the low 50's coupled with strong surface heating provided lifted indices below -5 at timing of initial convection. The forced lifting was suspected to be along a sharpened dry line which trended NE-SW very near MAF. Comparing MAF 00Z sounding with earlier 1200Z there was an increase of mid to upper level winds from southwestern advancing embedded shortwave. Developed Cells were high based and produced noted downburst from visual observations, at a distant, as well as personal observation of wet microburst as encountered. The first image is of an evolving downburst (pre contact stage) taken around 2345Z from Midland, looking distant approximately 15 miles, toward the south/southeast.

The next image is inferred to be at contact stage of a wet microburst, taken shortly thereafter, but not able to see ground from vantage point to see outward spread.


At this time it was decided to drive southeast along SH 158 toward Spraberry. In transit and along Florida Avenue nearing the Interstate 20 intersection, very strong straight line winds from combined outflow of suspected distant multiple small wet microbursts were encountered and judged to be in excess of 45 mph by witnessing fully extended whipping flags. In addition blowing dust had reduced visibility dramatically. While driving along SH 158 approximately 10 miles from Midland one east bound lane was obstructed by wind transported debris ( road construction materials). The strongest winds were encountered approximately 5 miles south of the SH 158 and 137 intersection accompanied by very heavy mixture of hail and rain which reduced visibility to less than 100 feet. Wind speeds were estimated to have exceeded 60 mph. It was assumed that such occurrence was right beneath a small wet microburst at the contact stage. The next image, on SH 137, was taken after visibility cleared enough in order to photograph during the outburst stage and presumed to have been directly earlier beneath the contact stage. The next two images were taken a short time later with clearing skies from the north which highlighted the rainbow, first, and second image of heavy runoff of rain and melted hail alongside road.

The final image was taken of another small wet microburst during the cushion stage as the moving multicelled complex continued to produce downbursts as it entered central Glasscock County County. Note the upward curling of rain/hail during this cycle of the small microburst on the left central side of image above ground level.