2 July 2020
Have you ever heard of a heat burst? If you have, you probably have not experienced one. These rare events are very localised and do not last long. I was lucky enough to experience one in Oklahoma City in the 1990’s but few meteorologists I know can say they were in one. An exception to the rule is my friend Richard “Heatwave” Berler. Richard is the Chief Meteorologist for KGNS TV in Laredo, Texas and he saw one last month. Below is his description:
Guest Post Richard Berler
A weather event, rarely observed, passed over the northern portion of Laredo, Texas at about 5 am Wednesday, June 10,2020. Hot downdraft winds occasionally reach the surface follow weakening nighttime thunderstorms. This phenomenon is often referred to as a heat burst.
They are rare because heated air from above usually does not have enough momentum to pierce through cooler air that often resides near the surface during the nighttime hours. That said, they may not be as rare as the occasional observations might suggest due their often very small ‘footprint”, the small amount of time that their impact is felt, and the tendency for these events to occur late at night. These factors likely mean that a given heat burst will have a good chance of missing an urban center, and due to their fleeting existence and time of day of occurrence, very few people are up to witness them.
In my case, the only other time that I’ve experienced a heat burst in Laredo was 40 years ago at ~1 am on May 24, 1980. A thunderstorm passed through Laredo around the 10 pm news time on the 23rd, dropping the temperature into the high 60’s. I went into a Denny’s Restaurant after the newscast, and when I came out, it felt hot and dry! The airport temperature had jumped up to 90ºF, and the dewpoint had dropped to 54ºF, indicative of dry air having arrived at the surface from drier conditions aloft. By the 2 am observation, the heat burst was gone, our temperature and dewpoint had returned to the 70’s.
The June 10, 2010 event was much more pronounced, and with the help of a variety of government agency and private weather stations, it was possible to see how sharp the boundary around it (in North Laredo) was. In this case, the thermometer that I am in charge of for the National Climate Center (NCEIS) read 86F before the storm arrived after the previous day’s ~100ºF heat. At 3:31 am during the height of the thunderstorm ( 1.51” of rain that fell), we bottomed out at 66F. The heat burst arrived over north Laredo at ~4:45 am, and peaked just after 5 am, and was over just after 5:10 am. My government thermometer reached 99ºF at 5:02 am! The airport on the east edge of town appears to have been near the southern edge of the heat burst. They reached 95ºF just after 5 am with a 54F dewpoint.