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Analysis and Prediction of Convective Initiation on 24 May, 2002

Analysis and Prediction of Convective Initiation on 24 May, 2002. June 14, 2004 Toulouse 2 nd IHOP_2002 Science Meeting. Ming Xue, William Martin and Geoffrey Stano School of Meteorology and Center for Analysis and Prediction of Storms University of Oklahoma.

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Analysis and Prediction of Convective Initiation on 24 May, 2002

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  1. Analysis and Prediction of Convective Initiation on 24 May, 2002 June 14, 2004 Toulouse 2nd IHOP_2002 Science Meeting Ming Xue, William Martin and Geoffrey Stano School of Meteorology and Center for Analysis and Prediction of Storms University of Oklahoma

  2. Our work on May 24, 2002 CI Case • MS Thesis work of Geoffrey Stano: Multi-scale study based-on ADAS analyses including special IHOP data sets, and by examining observations directly. • High-resolution simulation study (focus of this talk) • Very large (~2000) ensemble and adjoint I.C. sensitivity study. dP/dqv sensitivity fields.

  3. Objectives • Understand convective initiation in this case • Predict and understand the convective systems involved • Assess the sensitivity of precipitation forecast to initial conditions

  4. Methodology • Make use of special data sets collected during IHOP • Create high-resolution gridded data to perform diagnostic analysis and for model initialization • Verify model simulations against available data • Analyze realistic high-resolution model simulations to understand CI process

  5. Synopsis of the Event • Convection started between 20:00 and 20:30 UTC in Texas panhandle area along a dryline. An intensive observation of IHOP_2002. • Rapidly developed into a squall line and advanced across Oklahoma and northern Texas • SPC reported almost 100 incidents of large hail, 15 wind reports, and two tornadoes in central Texas

  6. Time and Location of Initiation(17UTC – 22 UTC)

  7. Isotach Analysis: 250mb 19 UTC 20 UTC TX Panhandle located at left-rear of upper level jet A short wave trough moved over western TX

  8. CIN and CAPE Analyses CIN 19UTC CIN 20UTC CAPE 20UTC CAPE 19UTC

  9. Results of Stano’s diagnostic study • Favorable condition pointing to initial initiation near Childress, TX • Placement of 250mb jet max and minimum • Surface heating and high surface dew points • Low Convective Inhibition values • Causes for initiation • Weakening of cap over the boundary layer by turbulently mixing • Break down of cap led to higher CAPE values • Convergence along the dryline or possibly from the cold front approaching dryline • More specifics limited by data resolutions

  10. Model Simulation Study • Model can provide much more complete data in both space and time • Easier to examine cause and effect • Model fields are dynamically consistent • Caution - model solution may deviate from truth therefore verification against truth is necessary

  11. Forecast Grids 4

  12. Model Configurations • 1 km grid nested inside 3 km one • ADAS analyses for ICs and 3 km BCs • NCEP ETA 18UTC and 00UTC analyses and 21UTC forecast used as analysis background • ARPS model with full physics, including ice microphysics + soil model + PBL and SGS turbulence • LBCs every 3h for 3km grid and every 15min for 1 km grid • 6 hour simulation/forecast, starting at 18 UTC

  13. OBS Used by ADAS • ARM • COAG • IHOP Composite Upper Air - rawinsondes • KS Ground Water District 5 • OK Mesonet • SAO • SW Kansas Mesonet • Western TX Mesonet • Profiler data absent

  14. Surface Data Sets

  15. Upper-Air Observing Sites

  16. Dropsondes on 20 UTC Isodrosotherms

  17. 20:02UTC

  18. 20:32UTC

  19. 21:02UTC

  20. 21:32UTC

  21. 22:02UTC

  22. 22:58UTC

  23. 23:58UTC

  24. Animation 20UTC-00UTC, KLBB radar

  25. Animation 20UTC-00UTC, KFRD radar

  26. 3km model simulation/forecast

  27. 1 km simulation

  28. T=2.5h 20:30UTC

  29. T=3.0h 21:00UTC

  30. T=3.5h 21:30UTC

  31. T=4.0h 22:00UTC

  32. T=4.5h 22:30UTC

  33. T=5h 23:00Z T=5h 23:00Z

  34. T=5.5h 23:30Z T=5h 23:00Z

  35. Animations • Surface reflectivity • 2km level w, winds See movies (18:30 UTC – 00:00 UTC)

  36. See Movies

  37. 19:16UTC

  38. 19:45UTC

  39. 20:30UTC

  40. 23:00UTC

  41. Vertical cross-section animations • w and q • w and qv • qv and qe See Movies

  42. See Movies

  43. +

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