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Heat burst

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In meteorology, a heat burst is a rare atmospheric phenomenon characterised by gusty winds and a rapid increase in temperature and decrease in dew point (moisture). Heat bursts typically occur during night-time and are associated with decaying thunderstorms.[1]

Although 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 denser than its surroundings.[2] The parcel descends rapidly, warming due to compression, overshoots its equilibrium level and reaches the surface, similar to a downburst.[3]

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 120 °F (49 °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.

Some documented cases

  • Bussey, Iowa, 3 May 2012: The temperatures shot from about 74 °F (23 °C) to about 85 °F (29 °C) degrees while peak wind gusts jumped from around 15 mph to about 60 mph.[4][5]
  • Torcy, Seine-et-Marne, 29 April 2012 : while an area of low pressure moved from the southwest of France to the northwest, the wind suddenly increased between 10 pm and midnight in areas to the south of Paris. Sustained winds topped 45 km/h (28 mph) at the station of Torcy (Seine-et-Marne) with gusts of up to 110km/h (69 mph). At the same time, the temperature rose from 13.4 °C (56.1 °F) at 11 pm to 24 °C (75 °F) at midnight. The vertical temperature profile was similar to that observed during dry downbursts, with a very strong helicity (700 m²/s²) and a strong shear (60 kts) but with only a weak instability (CAPE levels of 100 to 200 J/Kg). No thunderstorms developed over the region, however light rain was reported (due to evaporation in dry low level boundary layer). Other stations in the area also experienced the phenomenon but not as dramatically as in Torcy.[6]
  • Atlantic, Iowa, 23 August 2011: The observation at the Atlantic AWOS at 7:25 pm local time had a temperature of 102 °F (39 °C) and a dew point of 7 °F (−14 °C). Three observations prior to this (6:55 pm), the temperature was 88 °F (31 °C) and the dew point was 64 °F (18 °C). The 7 °F (−14 °C) dew point is considered likely to be incorrect, however, as AWOS stations have been known to have issues with dew points in low humidity environments. Scattered wind damage was also reported in association with the heat bursts, with one wind observation as high as 60 miles per hour (97 km/h).[7][8][9]
  • Indianapolis, Indiana, 3 July 2011: Observations around 1:30 am EDT in the area indicated the temperature rose and the dew point dropped nearly 15 °F (8 °C) in a less than an hour, causing the relative humidity to drop nearly 40-50%. Winds increased rapidly, with gusts to near 50 mph (80 km/h). One NWS Indianapolis employee reported that his neighbor's patio furniture ended up in his backyard. The observation site at Eagle Creek Airpark (KEYE) best observed the temperature, dew point, and pressure changes. The site at Indianapolis International Airport (KIND) observed the strongest wind gusts associated with the heat burst.[10]
  • Wichita, Kansas, 9 June 2011: Temperatures rose from 85 to 102 °F (29 to 39 °C) between 12:22 and 12:42 am. The heat burst caused some wind damage (40–50 mph or 64–80 km/h) and local residents reported the phenomenon to area weather stations.[11]
  • Buenos Aires, Argentina, 29 October 2009: After a day with extremely high and unusual temperatures that peaked over 93.9 °F (34.4 °C) (air temperature 101.6 °F (38.7 °C)), at late midnight temperatures rose from 87.8 to 94.2 °F (31.0 to 34.6 °C) in a matter of minutes with wind gusts over 37 miles per hour (60 km/h)[12]
  • Delmarva Peninsula, 26 April 2009: Temperatures rose from 68 to 87 °F (20 to 31 °C) between 10:00 pm and 2:00 am following a series of heat bursts across the Eastern Shore. Double-digit temperature increases were reported from 1:00 to 2:00 am at Salisbury, Maryland (+13), Ocean City, Maryland (+11), and Wallops Island, Virginia (+10).[13]
  • Sioux Falls, South Dakota, 3 August 2008: Temperatures rose rapidly from the lower 70 to 101 °F (21 to 38 °C) in a matter of minutes. Wind speeds also rose with gusts up to 50–60 mph (80–97 km/h).[14]
  • Cozad, Nebraska, 26 June 2008: Wind gusts reached 75 miles per hour (121 km/h), as the temperature rose 20 °F (11 °C)[15] in a matter of minutes.[16]
  • Midland, Texas, 16 June 2008: At 11:25 pm a wind gust of 62 mph (100 km/h) occurred, and the temperature rose from 71 to 97 °F (21.7 to 36.1 °C) in minutes.[17] (These measurements were taken from miles away, and theories point to 80–100 mph (130–160 km/h) winds in a 2–3-block perimeter.)[18]
  • Emporia, Kansas, 25 May 2008: Reported temperature jumped from 71 to 91 °F (21.7 to 32.8 °C) between 4:44 and 5:11 am (CDT)[19] as the result of wind activity from a slow moving thunderstorm some 40 miles (64 km) to the southwest.
  • Canby, Minnesota, 16 July 2006: A heat burst formed in Western Minnesota, pushing Canby's temperature to 100 °F (37.8 °C), and causing a wind gust of 63 mph (55 kn; 101 km/h). The dew point fell from 70 to 32 °F (21 to 0 °C) over the course of one hour.[20]
  • Hastings, Nebraska, 20 June 2006: During the early morning the surface temperature abruptly increased from approximately 75 to 94 °F (23.9 to 34.4 °C).[21][22]
  • Sheppard Air Force Base Wichita Falls, Texas, 12 June 2004: During late evening the surface temperature abruptly increased from approximately 83 to 94 °F (28.3 to 34.4 °C) and causing a wind gust of 72 mph (63 kn; 116 km/h). The dew point fell from 70 to 39 °F (21.1 to 3.9 °C)[23][24]
  • Minnesota and South Dakota, 26 March 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.[25]
  • Oklahoma, 22–23 May 1996: The temperature in the towns of Chickasha rose from 87.6 to 101.9 °F (30.9 to 38.8 °C) in just 25 minutes, while the temperature at Ninnekah rose from 87.9 to 101.4 °F (31 to 39 °C) in 40 minutes. In addition, wind damage was reported as winds gusted to 95 mph (153 km/h) in Lawton, 67 mph (108 km/h) in Ninnekah, and 63 mph (101 km/h) in Chickasha.[26]
  • Kopperl, Texas, 1960: A heat burst sent the air temperature to near 140 °F (60 °C), supposedly causing cotton crops to become desiccated and drying out vegetation.[27]
  • Portugal, 6 July 1949: A heat burst reportedly drove the air temperature from 38 to 70 °C (100.4 to 158.0 °F) two minutes later (note that the highest temperature formally recognized on the Earth is 56.7 °C (134.1 °F) in Death Valley in 1913.).[28]
  • Cherokee, Oklahoma, 11 July 1909: at 3:00 in the morning, a heat burst south of Cherokee, Oklahoma reportedly caused the temperature to rise briefly to 136 °F (57.8 °C), desiccating crops in the area.[29]

See also

References

  1. ^ American Meteorological Society. (2000). Glossary of Meteorology. American Meteorological Society. ISBN 1-878220-34-9.
  2. ^ "Oklahoma "heat burst" sends temperatures soaring". USA Today. 8 July 1999. Retrieved 9 May 2007.
  3. ^ Johnson, Jeffrey (2003). "Examination of a Long-Lived Heat Burst Event in the Northern Plains". National Weather Digest. 27. National Weather Association: 27–34. {{cite journal}}: Unknown parameter |month= ignored (help) [dead link]
  4. ^ "Rare phenomenon leads to bizarre weather event in Central Iowa". Des Moines Register.
  5. ^ "Rare heat burst just occurred in Iowa". KCCI.
  6. ^ "24°C en Île-de-France la nuit dernière, des rafales à 110 km/h !". METEO CONSULT - La Chaine Météo / Groupe Figaro.
  7. ^ "Heat Burst Affects Southwest Iowa". National Weather Service Des Moines, Iowa.
  8. ^ "Rare "Heat burst" hits Atlantic area". Radio Iowa.
  9. ^ "Temps Rocket From 80s to 102 in Minutes". KCCI.
  10. ^ "Heat Burst Occurs in the Indianapolis Area".
  11. ^ http://www.kwch.com/kwch-jab-did-you-feel-this-mornings-heat-burst-20110609,0,5006130.story
  12. ^ Heat Burst in Buenos Aires
  13. ^ http://www.erh.noaa.gov/akq/wx_events/severe/HeatBurst42609/heatburst_20090426.htm
  14. ^ Convective Heat Burst moves across Sioux Falls
  15. ^ http://www.evri.com/location/cozad-nebraska-0xfa154
  16. ^ NTV - KHGI/KWNB/WSWS-CA - Where your news comes first. - Grand Island, Kearney, Hastings, Lincoln | Cozad Witnesses Rare Weather
  17. ^ http://www.mywesttexas.com/articles/2008/06/17/news/top_stories/doc4857af7c54b33314052160.txt
  18. ^ Midland Heat Burst - Damage Survey
  19. ^ "Special Weather Statement". National Weather Service, Topeka, Kansas. Retrieved 25 May 2008.
  20. ^ "Late Night Heat Burst in Western Minnesota on 16–17 July 2006". National Weather Service, Twin Cities. Retrieved 9 May 2007.
  21. ^ History : Weather Underground
  22. ^ Heat Bursts Occur Across South-Central Nebraska Early Tuesday Morning, 20 June.
  23. ^ http://www.srh.noaa.gov/oun/wxhistory/gethistory.php?month=06
  24. ^ http://www.storm2k.org/phpbb2/viewtopic.php?f=24&t=31351&start=0&st=0&sk=t&sd=a
  25. ^ Heitkamp. "Tri State Area Heat Burst March 26, 1998". National Weather Service, Sioux Falls. Retrieved 9 May 2007. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  26. ^ Cappella, Chris (23 June 1999). "Heat burst captured by weather network". USA Today. Retrieved 9 May 2007.
  27. ^ Petricic, Dusan (2000). "It's Raining Eels: A Compendium of Weird Weather". Scientific American Presents: 54–55. issn = 1048-0943. {{cite journal}}: Missing pipe in: |id= (help)
  28. ^ Freaks of the Storm, Randy Cerveny 2006, ISBN 1-56025-801-2
  29. ^ Isaac M. Cline, Climatological Data for July, 1909: District No. 7. Lower Mississippi Valley, p 337-338; http://ams.allenpress.com/perlserv/?request=get-toc&issn=1520-0493&volume=37&issue=7 Monthly Weather Review July 1909
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