The diurnal temperature pattern is usually pretty straightforward. On most days, the temperature rises during the day when the sun is up, and falls at night. Occasionally, the temperature will fall during the day after a cold front passes. Sometimes, the temperature rises slightly at night after a warm from passes. Rarely, though, does the temperature rise at night like it did last night in Nebraska. A heat burst occurred in the early-morning hours on June 11, 2013 that sent the temperature soaring from the 70s to the upper 90s in parts of Nebraska. A warm and muggy night turned into a hot and dry night as strong winds descended out of a weakening thunderstorm. The following data is fromt the National Weather Service office in Hastings, NE.
Before Heat Burst
After Heat Burst
|Grand Island Airport ASOS||73/67 (2:53 a.m.)||99/41 (5:10 a.m.)|
|Hastings Airport ASOS||73/66 (1:53 a.m.)||97/39 (3:53 a.m.)|
|Holdrege Airport AWOS||77/68 (12:35 a.m.)||88/47 (2:35 a.m.)|
|Kearney Airport AWOS||75/66 (12:55 a.m.)||97/43 (3:15 a.m.)|
|Lexington Airport AWOS||79/68 (11:55 p.m.)||87/48 (2:15 a.m.)|
|Aurora Airport AWOS||73/63 (5:37 a.m.)||91/46 (6:38 a.m.)|
A heat burst occurs when a thunderstorm weakens over a layer of dry air. Rain falling through the dry air will evaporate causing the air to cool. The area of cooler air is more dense than the surrounding air and it continues to descend. When the precipitation associated with the descending air completely evaporates, it can no longer cool, but the momentum built up by the descending parcel of air is strong enough that it continues moving toward the ground at a high rate of speed. When dry air descends it heats up, and the result at the surface is a strong burst of wind that brings much warmer, drier air.