Drought has rapidly expanded across parts of the nation, including livestock production areas over the Southeast U.S. and Texas.
A flash drought is defined as the sudden onset of unusually high temperatures along with significant decreases in soil moisture. Flash droughts tend to intensify rapidly over the spring and summer months.
There are two types of flash droughts.
A Type 1 flash drought is based on unusually high temperatures which increase evapotranspiration and decrease soil moisture. Type 1 flash droughts are most likely within areas shaded in green (left). Type 1 Flash Drought Only about 4-5% of total record. Occur in the eastern U.S. with maxima over the North Central U.S. and the Ohio River Basin (areas shaded in green above.) Primarily temperature driven. Can only occur in vegetation dense areas.
A Type 2 flash drought starts from the lack of spring rainfall. With a lack of rainfall, evapotranspiration decreases, setting the stage for possible (negative) feedback and resulting unusually hot temperatures. Type 2 Flash Drought More common than Type 1, about 5-8% of total record. Maximum over the Southern Plains and the Gulf states (areas shaded in red above). Mainly precipitation driven - tends to occur during meteorological drought. Lack of precipitation will increase surface temperatures and result in heat waves.
Drought has rapidly developed and expanded across parts of the eastern U.S., especially Mid-Atlantic and southeastern states. This drought formed due to a significant lack of rainfall over the late summer and so far early this fall. As this drought formed rapidly, generally over the past 30 to 60 days, it seems to fit the pattern for a Type 2 Flash Drought.
Extensive drought covers much of Texas. Some areas are reporting extreme (D3 - red) conditions.
Drought within this area developed slower -- entering the summer months. Due to the gradual development of drought in Texas, it is more likely a traditional drought than a flash drought.
Persistent patterns of temperature and precipitation lead to the formation of droughts. It will take a sustained and significant change in these patterns, or an unusual event such as an inland-moving tropical system, to begin to ease these drought impacts.
Fall is typically one of the quietest times of the year so it is likely that drought impacts could persist over the Southeast U.S. and Texas through much of the remainder of 2019.
Here is NOAA’s drought outlook through the end of the year.