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19 July 2006 Derecho: A Meteorological Perspective and Lessons Learned from this Event

19 July 2006 Derecho: A Meteorological Perspective and Lessons Learned from this Event. Ron W. Przybylinski, James E. Sieveking, Benjamin D. Sipprell NOAA / National Weather Service St. Louis Jared L. Guyer NOAA/NWS/NCEP Storm Prediction Center. 2009 Spring Media Workshop.

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19 July 2006 Derecho: A Meteorological Perspective and Lessons Learned from this Event

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  1. 19 July 2006 Derecho:A Meteorological Perspective and Lessons Learned from this Event Ron W. Przybylinski, James E. Sieveking, Benjamin D. Sipprell NOAA / National Weather Service St. LouisJared L. GuyerNOAA/NWS/NCEP Storm Prediction Center 2009 Spring Media Workshop

  2. Outline of this Presentation • Synoptic scale conditions the morning of 19 July 2006 • Storm overview (large scale perspective) • Mesoscale Environment during the afternoon of 19 July 2006 over southern Iowa, Missouri and Illinois. • WSR-88D Doppler radar analysis of the storm complex from WFO Lincoln Illinois and WFO St. Louis perspectives. • Some final comments

  3. Upper Air Analysis - 1200 UTC 19 July 2006 250 mb analysis 500 mb analysis

  4. Upper Air Analysis - 1200 UTC 19 July 2006 850 mb analysis RUC 700-500 mb lapse rate (°C km-1)

  5. 1200 UTC DVN Observed Raob

  6. Radar Imagery Composites and 06z SPC Outlook Composite base reflectivity 1210 UTC SPC radar animation 1200-1315 UTC

  7. Radar Imagery Composites and 13z SPC Outlook Composite base reflectivity 1610 UTC SPC radar animation 1454-1615 UTC

  8. Hourly MCS Track and Storm Reports

  9. 1800 UTC Surface Analysis 19 July 2006

  10. RUC 00-hr Sounding for SPI at 2100 UTC

  11. 18 19 20 21 22 17 Winchester, IL (WNC) Profiler 1700 - 2200 UTC

  12. SPC Mesoscale analysis for MLCAPE and 0-6 km bulk shear at 2300 UTC MLCAPE ranged from 2000 – 6000 J kg-1 acrosseastern Missouri throughwest-central Illinois Deep layer shear weak with magnitudes of 10 – 22 m s-1

  13. RUC 00-hr Sounding for STL at 2300 UTC

  14. Parker’s Study on Linear MCS archetypes The 19 July 2006 Damaging Wind Convective system followed theParallel Stratiform (PS) archetype

  15. WSR-88D Radar Imageryfrom Lincoln Illinois (KILX)at 2138 UTC Parallel Stratiform Parker and Johnson 2000

  16. Conceptual model of a multicell cluster storm complex.(NSSL)

  17. KLSX radar imagery for 2332 UTC 2332 UTC Radar imagery from St. Louis (KLSX). The strongest winds were associated with convective segment #3 (larger echo mass).Several witnessesover southern Macoupin County experience hail up to nickel size with the stronger downbursts behind the leading gust front.

  18. I Was Here! 7:01 PM CDT Reflectivity (left), Base velocity (right). The strongest winds were detected with the higher reflectivity cores over northwest Madison County Illinois.

  19. Loop of the evolution of a single severe cell over the western part of the storm complex.

  20. Bunker Hill ASOS / AWOS Surface Observation sites around the GreaterSt. Louis metro area.

  21. When was the last time we documented a case similarto the July 19, 2006 Derecho? Aug 10, 1992. The convective complex formed just southwest of KLSXand moved south-southward through west-central Arkansas. Widespread wind damage occurred with this derecho.

  22. The July 19 2006 damage map reveals that much of the downbursts was oriented from north-northeast to south-southwest – an unusual direction.This direction of damaging winds future intensified the degree of damage over the greater St. Louis metro area.

  23. Tower Grove Park

  24. Summary • On 19 July 2006 formed over northeast Iowa and causedsevere wind damage from parts of northeast Iowa through central Illinois and then south-southwest across the Greater St. Louis metro area and then into southwest Missouri.(A typical movement). • -Over 500,000 people were without power from this windstorm. The oppressive HEAT AND HUMIDTYafter this event brought suffering to a large part of the population. - The environment over the Mid-Mississippi Valley regionwas extremely unstable with ML CAPEs of 2600 to 6000 J/Kg while a deep layer shear was weak (< 22 m s-1 )

  25. RUC sounding at 2300 UTC from STL showed a very weak cap.- The upper-level ridge over the central plains built eastwardinto Illinois allowing the MCS to move in a south-southwestdirection during the late afternoon and evening. - The overall storm morphology took on the characteristics of “parallel stratiform” type system where three convective segments showed “pulse – multicellular” characteristics. - Convective segment #3 (eastern most storm) was themost consistent storm complex of the three groups. -

  26. Surface winds along the leading edge of the gustfront varied between 20 to 31 m s-1. - The strongest surface winds were associated with the isolated convective towers through the area of mature convection. Wind speed estimates – 40 m s-1 • - This wind storm was one of the more challenging cases, from both a national and local WFO perspective.

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