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20 May 2009 HeatBurst Across South Central North Dakota

Patrick J. Ayd and Joshua W. Scheck NOAA/National Weather Service – Bismarck, ND. 20 May 2009 HeatBurst Across South Central North Dakota. Outline. How rare are heat bursts? Ingredients for a heat burst? Review of the 20 May 2009 Heat Burst Significance in operations. How Rare Are They?.

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20 May 2009 HeatBurst Across South Central North Dakota

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  1. Patrick J. Ayd and Joshua W. Scheck NOAA/National Weather Service – Bismarck, ND 20 May 2009 HeatBurst Across South Central North Dakota

  2. Outline • How rare are heat bursts? • Ingredients for a heat burst? • Review of the 20 May 2009 Heat Burst • Significance in operations

  3. How Rare Are They? • In order for a heat burst to be noticed it either has to be reported by a spotter, or seen within surface observational data. • How often do spotters not report weather phenomena? • Would you notice a rapid rise in temperature at a non ASOS site?

  4. How Rare Are They? • Dependent on the density of the observational network, and actually having the phenomena pass over the sensors. • Do we actively seek to find a heat burst?

  5. How Rare Are They? • The rarity of a heat burst may be due in large part to our inability to sense microscale events and properly analyze all data sources to acknowledge their presence.

  6. Heat Burst • Ingredients: • High LCL • Large subcloud dewpoint depression • Shallow nocturnal inversion – How shallow? • Cumulonimbus cloud/Downdraft initiation

  7. Mesoscale: 20 May 2009 06 UTC HPC Surface Analysis

  8. 07 UTC 850 hPa RUC Analysis

  9. 07 UTC 500 hPa RUC Analysis

  10. 07 UTC 700-500 hPa Lapse Rate

  11. 07 UTC LFC

  12. 07 UTC Downdraft CAPE

  13. 07 UTC MU CAPE/ LCL-LFC RH

  14. 7 UTC 20 May 2009ProximityNAM BUFR Sounding

  15. 00 UTC 20 May 2009Bismarck Sounding

  16. KBIS 4.3 Base Reflectivity

  17. KBIS 4.3 635 UTC

  18. KBIS 4.3 705 UTC

  19. 0705 UTC KBIS 0.5° Velocity

  20. Heat Burst 7 Miles South of St. Anthony • 235 am CDT 20 May 2009 • Two thermometers in spotter’s yard read 90.5 and 95.6 respectively. • 8 foot corral doors blown 25 ft from their rail road ties

  21. Flasher, North Dakota APRS

  22. Tatanka Prairie RAWS

  23. Buffalo

  24. Significance • How does this play into operations?

  25. Significance • Low POD, High FAR for any attempts at High Wind Warnings. • Best served by Nowcasts, SPS and AFDs • Be sure to include inherent uncertainty in the timing, location and severity of the event. • Can we tell the difference between a shallow inversion that can be displaced and one that cannot?

  26. Questions • Thank You

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