Heat burst
From Wikipedia, the free encyclopedia
A heat burst is a rare atmospheric phenomenon characterised by gusty winds and a rapid increase in temperature and decrease in dew point. Heat bursts typically occur during night-time and are associated with decaying thunderstorms. While this phenomenon is not fully understood, it is theorized that the event is caused when rain evaporates (virga) into a parcel of cold dry air high in the atmosphere making the air more dense than its surroundings.[1] The parcel descends rapidly, warming due to compression, overshoots its equilibrium level and reaches the surface, similar to a downburst.[2] Recorded temperatures during heat bursts have reached well above 90 °F (32 °C), sometimes rising by 20 °F (11 °C) or more within only a few minutes. More extreme events have also been documented, where temperatures have been reported to exceed 130 °F (54 °C), although such extreme events have never been officially verified. Heat bursts are also characterised by extremely dry air and are sometimes associated with very strong, even damaging, winds.
[edit] Documented Cases
- Emporia, Kansas saw its reported temperature jump from 71 °F (22 °C) to 91 °F (33 °C) between 4:44am and 5:11am (CDT) on 25 May 2008[3] as the result of wind activity from a slow moving thunderstorm some 40 miles to the southwest.
- On 16 July 2006, a heat burst formed in Western Minnesota, pushing Canby's temperature to 100 °F (38 °C), and causing a wind gust of 63 mph (55 kn/101 km/h). The dew point fell from 70 °F (21 °C) to 32 °F (0 °C) over the course of one hour.[4]
- Hastings, Nebraska experienced a heat burst during the early morning of 20 June 2006 when surface temperatures abruptly increased from approximately 75 °F (24 °C) to 94 °F (34 °C).[citation needed]
- Oklahoma, May 22-23, 1996: The temperature in the towns of Chickasha rose from 87.6 °F (31 °C) to 101.9 °F (39 °C) in just 25 minutes, while the temperature at Ninnekah rose from 87.9 °F (31 °C) to 101.4 °F (39 °C) in 40 minutes. In addition, wind damage was reported as winds gusted to 95 mph (83 kn/153 km/h) in Lawton, 67 mph (58 kn/108 km/h) in Ninnekah, and 63 mph (55 kn/101 km/h) in Chickasha. [5]
- Minnesota and South Dakota, March 26, 1998: A temperature increase of 10-20 °F (6-11 °C) was reported in the towns of Marshall, Minnesota, Sioux Falls, South Dakota, Brookings, South Dakota, and Montrose, South Dakota during a two-hour period.[6]
- In 1960, the town of Kopperl, Texas, experienced a heat burst sending the air temperature to near 140 °F (60 °C), supposedly causing cotton crops to become desiccated and drying out vegetation.[7]
- In Portugal in July 1949, a heat burst reportedly drove the air temperature from 38 °C (100 °F) to 70 °C (158 °F) two minutes later (note that the highest temperature formally recognised on the Earth was 57.8 °C (136 °F) in Libya in 1922, and the former record has not been verified).[8]
[edit] External links
- P11.13 THE 22-23 MAY 1996 HEATBURST: A SEVERE WIND EVENT
- What is a Heat Burst?
- Heat Burst Affected Portions of west central and central Minnesota
[edit] References
- ^ Oklahoma "heat burst" sends temperatures soaring. USA Today. Retrieved on 2007-05-09.
- ^ Johnson, Jeffrey (December 2003). "Examination of a Long-Lived Heat Burst Event in the Northern Plains". National Weather Digest 27: 27–34. National Weather Association.
- ^ Special Weather Statement. National Weather Service, Topeka, Kansas. Retrieved on 2008-05-25.
- ^ Late Night Heat Burst in Western Minnesota on July 16-17, 2006. National Weather Service, Twin Cities. Retrieved on 2007-05-09.
- ^ Cappella, Chris (1999-06-23). Heat burst captured by weather network. USA Today. Retrieved on 2007-05-09.
- ^ Heitkamp; Holmes. Tri State Area Heat Burst March 26, 1998. Retrieved on 2007-05-09.
- ^ Petricic, Dusan (2000). "It's Raining Eels: A Compendium of Weird Weather". Scientific American Presents: 54–55. ISSN: 1048-0943.
- ^ Freaks of the Storm, Randy Cerveny 2006, ISBN 1-56025-801-2