A heat burst occurred over parts of northwest Oklahoma last night, beginning around 10 pm and lasting until around 5 am. Temperatures well after dark warmed above 90 degrees, and winds gusted 55 to 65 mph at times as seen in the map below. The event lasted between one and two hours at a specific site, which is right about average. Luckily, no damage was reported with the strong winds.
We are getting into that time of year when heat bursts become more common, and many questions arise about the origins of these phenomenon. More research has been done on heat bursts recently, so we are getting a better understanding on why they occur, and can even forecast these in advance. Some facts about heat bursts are:
Last night a thunderstorm complex moved out of the Texas panhandle and moved into stable air over Oklahoma. The 00Z upper air sounding out of Dodge City, KS (close to where the heat burst occurred) showed a large column of dry air below 500 mb. The sounding from Norman, OK also showed the column of dry air, although not quite as significant. As the thunderstorms moved east into this less favorable environment, they began to decay. Basically, the updraft in the thunderstorm shut off, leaving only the downdraft portion of the storm. As the precipitation in the downdraft fell into the environmental dry air, it evaporated and cooled. The cooler air was now very dense and further accelerated toward the ground. After all the precipitation has evaporated, the air no longer cools, but begins to warm up due to compression. The air now is warming dramatically and has now become more buoyant (warmer than its surroundings), and it slows down. Even though it is slowing down, the downward momentum is so great that the downdraft makes it all the way to the surface. Winds in excess of 50 mph were reported, and temperatures warmed into the upper 80s and lower 90s. The peak wind gust occurred at Gage ASOS, measuring 66 mph and the highest temperature occurred in Harper county, reporting 93 degrees.
Significant heat burst events have occurred in the past, with the most signficant even occurring on May 22nd, 1996. The temperature at Chickasha and Ninnekah both rose above 100 degrees, and winds in excess of 60 mph were reported over several areas in southwest Oklahoma. Damage to trees, power lines, and rooftops was reported. Other stories (unverified) claim to have seen the temperature rise well over 100 degrees. These extreme events are rare, but are quite signficant when they occur.