(AP) — A so-called heat burst caused temperatures to briefly soar in southern Nebraska.

Rick Chermok, of the National Weather Service, says the temperature in Lincoln rose from 73 to 91 degrees between 8 a.m. and 9 a.m. Tuesday.

In Grand Island, it spiked from 73 to 99 degrees between 2 a.m. and 5 a.m.

Similar surges were noted in Hastings, Kearney and elsewhere.

Heat bursts occur when specific conditions exist.

Thunderstorms must be diminishing above a layer of dry air. Rain from those storm falls into drier air and evaporate, making the air cooler than surrounding air.

The cooler air sinks, causing atmospheric pressure to increase and warm the air again. Because of momentum, the air pushes to the surface and spreads out, causing temperatures to spike and winds to increase.