A “flash drought” is similar to a “flash flood.” In a flash drought, a sudden, unexpected burst of high temperatures and low humidity comes into an area and stays for an extended period of time.
 
The term “flash drought” was used in 2001 by climatologist Mark Svoboda of the National Drought Mitigation Center (NDMC) at the University of Nebraska-Lincoln, and the NDMC possibly coined the term.
 
   
Google News Archive
28 August 2001, Ludington (MI) Daily News, “State’s farmers battling high weather” by Patti Klevorn (AP), pg. A3, col. 5:
Mark Svoboda, a climatologist with the National Drought Mitigation Center at the University of Nebraska-Lincoln, said Michigan and Ohio have the only areas of severa drought in the Midwest.

Svoboda said he considers the recent dry weather a flash drought.
 
“This is really come on hard and fast,” he said. “You have a. time with no and high temperatures, and things can deteriorate pretty rapidly.”
 
15 December 2001, St. Albans (VT) Messenger, “A flash flood? How about a flash drought?” by Christopher Graff (AP), pg. 4, col. 1:
The summer changed the picture so quickly and so dramatically that state climatologist Lesley-Ann Dupigny-Giroux said climatologists are “exploring the concept of a flash drought in a similar fashion to the speed with which flash floods develop.”
 
Google Books
Forest Insect and Disease Conditions in the United States
United States. Forest Service, United States. Forest Pest Management, United States. Forest Health Protection
The Service, 2007
Pg. 171:
A term, “flash drought,” was coined by the Minnesota State Climatologic group to refer to a relatively sudden drought onset brought on by the prolonged absence of significant precipitation during the middle of a hot growing season.
   
Mother Jones
Flash Drought
—By Julia Whitty | Thu Aug. 11, 2011 12:44 PM EDT
This week’s US Drought Monitor reports the sudden emergence of drought in the Corn Belt states of South Dakota, Iowa, Illinois, and Indiana. Extreme heat combined with below average rainfall have stressed corn plants—often in areas where planting was already behind schedule due to an extremely wet spring.
   
NPR
‘Flash Drought’ Threatens To Destroy Mo. Crops
MAY 28, 2012 3:00 PM ET
ADAM ALLINGTON
Climatologists call it a “flash drought,” a sudden, unexpected burst of high temperatures and low humidity that can wither crops in a matter of days. And with temperatures hovering above 90 degrees, farmers worry the weather could have disastrous consequences on corn and other crops.
 
CBS News
By KAREN BROWN August 2, 2012, 6:22 AM
Drought decimates Arkansas’ famed cattle industry
(CBS News) SEARCY, Ark. - One by one, long cattle trailers in bright green and barnyard red slowly pull up to the Arkansas Cattle Auction.
(...)
The extreme flash drought—meaning it came on unexpectedly and isn’t letting up—is decimating Arkansas’ cattle industry. Without grass to graze on, owners are having to dip into their winter hay if they have it, or pay $70 per bail of hay that in good times would cost $40.
 
Sugar Land (TX) Sun
Commissioners issue burn ban in county
Posted: Tuesday, August 11, 2015 7:15 pm
By Rod Evans
(...)
While the U.S. Drought Monitor, established in 1999 and produced jointly by the National Oceanic and Atmospheric Administration, the U.S. Department of Agriculture and the National Drought Mitigation Center, indicates that much of southeast Texas is experiencing “abnormally dry” conditions and is not officially in a drought, Stuart Coombs, a wildland and urban interface specialist with the Texas A&M Forest Service, says the entire region has drifted toward drought status since the rains of May and early June evaporated.
 
“The current drying trend is no parallel with conditions of the 2011 fire season,” Coombs said. “That year resulted in a longer period of time where drought conditions eventually evolved into a real significant drought. The term that’s been coined recently is ‘flash drought,’ which is what the Fort Bend County area is in. It refers to the rapid swing from the wet conditions in early June to what we’ve experience in July and August.”
 
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Jasper-Newton-Sabine Counties Emergency Management
August 11, 2015
Flash drought is the term of the day. Flash drought was coined for the rapid swing from wet conditions in June to the dry conditions presently.
 
The eastern Piney Woods has seen its driest 30-day period of record, which dates back 121 years. The upper Texas coast is currently experiencing the second driest 30-day period, and the Texas Hill Country is going through its third driest.