9:30 AM CDT | June 24, 2018
Severe Storms fired in western North Texas late yesterday. These organized into Supercells capable of Very Large Hail and Damaging Winds. Baseball-size Hail was reported to the west of Abilene in Colorado City. A 87 MPH Wind Gust was reported with a storm north of Grape Creek, which is located to the northwest of San Angelo. There was another intense Supercell that was located north of Olney that was capable of 80 MPH Winds and Softball-size Hail. As of this post, however, there have been no reports confirming those possible hazards, as it tracked over a fairly rural area.
The atmosphere was primed for strong winds to be carried down to the surface as storms collapsed. We discussed this here on the blog and Facebook page yesterday. What also happened was a phenomena called a "heat burst". It typically occurs during the evening or overnight hours with collapsing thunderstorms. Basically, there has to be dry air very high in the atmosphere. Precipitation falling into dry air aloft will cause the air to cool through latent heat absorption. With a heat burst, however, the precipitation that cooled the air aloft has been vaporized. It can no longer absorb heat, so as the air rapidly accelerates toward the surface, it heats up. At the surface, you see strong winds, warming temperatures, and falling dew points and humidity.
Take a look at the observations from Eastland, Texas. At 12:15 AM, the temperature was 79*F with a dew point of 63*F. By 12:55 AM, the temperature had risen to 96*F! The dew point had dropped to 45*F. The environment gradually stabilized over the next few hours with upper-70*F's returning before 5:00 AM. Other locations reported heat bursts too, but they were not as intense as what was seen in Eastland. Abilene, Coleman, San Angelo, Ranger, and Comanche reported heat bursts. Coleman's temperature went from 93*F at 9:54 PM to 72*F at 10:34 PM as a result of rain from a thunderstorm. By 11:14 PM, it had risen to 84*F from a heat burst. The temperature fluctuated, rising to 88*F at 1:34 AM. It was around 2:30 AM by the time temperatures returned to the 70*F's.