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The Extreme East-Central Missouri Flash Flood of 6-7 May 2000 James T. Moore, John P. Gagan

The Extreme East-Central Missouri Flash Flood of 6-7 May 2000 James T. Moore, John P. Gagan Cooperative Institute for Precipitation Systems Department of Earth and Atmospheric Sciences Saint Louis University and Fred H. Glass NWSFO St. Charles, MO.

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The Extreme East-Central Missouri Flash Flood of 6-7 May 2000 James T. Moore, John P. Gagan

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  1. The Extreme East-Central Missouri Flash Flood of 6-7 May 2000 James T. Moore, John P. Gagan Cooperative Institute for Precipitation Systems Department of Earth and Atmospheric Sciences Saint Louis University and Fred H. Glass NWSFO St. Charles, MO Hydrometeorology Course for RFC/HPCFriday, 8 December 2000

  2. Extreme Heavy Rain in Franklin County, Missouri • Occurred during the nighttime and early hours of 6-7 May 2000 • Rainfall exceeding 4 inches (100 mm) fell over a 5500 km2 area, with embedded amounts over 12 inches (300 mm) • There were two fatalities and property damage of over 100 million dollars • 379 structures damaged or destroyed in Franklin County; declared a disaster area by the President • Flat Creek in Franklin County rose about 15 feet (4.57 m) destroying two mobile home parks.

  3. Flat Creek Watershed – Union, MO

  4. Infrared Satellite Imagery Valid 1815 UTC 5 May 2000 to 1815 UTC 6 May 2000

  5. NIDS Radar Imagery Valid 0134 to 1800 UTC 6 May 2000 http://www.rap.ucar.edu/staff/pneilley/NIDS_archives.html

  6. 24-Hour Precipitation Analysis for the Period Ending 1200 UTC 7 May 2000

  7. Accumulated Rainfall (Grey) 30 Minute Rainfall (Blue)

  8. GOES-8 Infrared Satellite Loop Valid 1815 UTC 6 May 2000 to 1815 UTC 7 May 2000

  9. Pre-storm Environment • Weakening mid-level cyclonic vortex (MCV) with warm core characteristics moving northeasterly from northeast Oklahoma into central Missouri. • Very moist tropospheric conditions: • 1000-500 mb mean relative humidity values > 80% • Lower tropospheric dewpoints in lower-middle teens ºC • PWs of 1.19 - 1.47 inches (153-216%) • warm cloud depths ranged from 3.1 –3.3 km • Weak instability with CAPEs between 500-1000 J kg-1 • Weak vertical wind shear in the mid-upper levels • Strong Low-Level Jet (LLJ) from the south-southwest (at times exceeding 50 knots)

  10. 925 mb surface 7 May 2000 00 UTC ---- Isodrosotherms

  11. 925 mb surface 7 May 2000 12 UTC ---- Isodrosotherms

  12. 850 mb surface 7 May 2000 00 UTC --- Isotachs

  13. 850 mb surface 7 May 2000 12 UTC --- Isotachs

  14. 500 mb surface 7 May 2000 00 UTC --- Isotherms

  15. 500 mb surface 7 May 2000 12 UTC --- Isotherms

  16. 250 mb surface 7 May 2000 00 UTC --- Isotachs

  17. 250 mb surface 7 May 2000 12 UTC --- Isotachs

  18. THE EVENT • A mesoscale convective system (MCS) formed near the center of the MCV and created an outflow boundary at the surface • This outflow boundary was weak, due to the very moist atmosphere in which it formed, and moved very little during the nighttime hours of 7 May 2000 • The southwesterly LLJ was strong and wide. It flowed nearly perpendicular to the outflow boundary, veering as time progressed, and acted as a focusing mechanism for convection

  19. THE EVENT (cont.) • The steering flow (from 700 mb to 300 mb) was predominantly westerly, veering as time progressed, and was oriented parallel to the outflow boundary • The nature of the training changed with time from west-east to northwest-southeast in concert with a change in cell motion • This change in cell motion was related to veering of the cloud-layer wind

  20. Surface Analysis Valid 00 UTC 7 May 2000 14 15 13 16 17 11 10 18 10 11 11 12 17 12 13 14 15 16 18

  21. Surface Analysis Valid 04 UTC 7 May 2000

  22. Surface Analysis Valid 06 UTC 7 May 2000

  23. Surface efor 06 UTC 7 May 2000

  24. Surface Analysis Valid 08 UTC 7 May 2000

  25. Surface efor 08 UTC 7 May 2000

  26. Surface Analysis Valid 10 UTC 7 May 2000

  27. Surface efor 10 UTC 7 May 2000

  28. RUC Initialization Composite Chart Valid 12 UTC 6 May 2000 Precipitable Water (1.2 inches) 1000-500mb Mean RH (%) K-Index(28)

  29. RUC Initialization Composite Chart Valid 00 UTC 7 May 2000 Precipitable Water (1.2 inches) 1000-500mb Mean RH (%) K-Index(28)

  30. RUC Initialization Composite Chart Valid 12 UTC 7 May 2000 Precipitable Water (1.3 inches) 1000-500mb Mean RH (%) K-Index(28)

  31. Springfield, MO (SGF) Skew-T Valid 00 UTC 7 May 2000 wcd = 3.02 km

  32. Springfield, MO (SGF) Skew-T Valid 12 UTC 7 May 2000 wcd = 3.27 km

  33. Lincoln, IL (ILX) Skew-T Valid 00 UTC 7 May 2000 wcd = 3.0 km

  34. Lincoln, IL (ILX) Skew-T Valid 12 UTC 7 May 2000 wcd = 3.31 km

  35. RUC Initialization 950 mb to 850 mb Layer-Averaged Wind Vectors and Isotachs Valid 00 UTC 7 May 2000

  36. RUC Initialization 950 mb to 850 mb Layer-Averaged Wind Vectors and Isotachs Valid 03 UTC 7 May 2000

  37. RUC Initialization 950 mb to 850 mb Layer-Averaged Wind Vectors and Isotachs Valid 06 UTC 7 May 2000

  38. RUC Initialization 950 mb to 850 mb Layer-Averaged Wind Vectors and Isotachs Valid 09 UTC 7 May 2000

  39. RUC Initialization 950 mb to 850 mb Layer-Averaged Wind Vectors and Isotachs Valid 12 UTC 7 May 2000

  40. Vertical Wind Profile Display from the KLSX WSR-88D Valid 0600 UTC to 0700 UTC 7 May 2000

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