1 / 26

A Comparison of Iowa Flash Flood Events and Eight Common Features of Excessive Rainfall for 2006-2011

Brittany Konradi 1 Mentors: Melinda Beerends 2 and Dr. Kristie Franz 1 Iowa State University 1 , NWS Des Moines 2. A Comparison of Iowa Flash Flood Events and Eight Common Features of Excessive Rainfall for 2006-2011. Outline. Background Information Methodology Analysis and Results

azana
Télécharger la présentation

A Comparison of Iowa Flash Flood Events and Eight Common Features of Excessive Rainfall for 2006-2011

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Brittany Konradi1 Mentors: Melinda Beerends2 and Dr. Kristie Franz1 Iowa State University1, NWS Des Moines2 A Comparison of Iowa Flash Flood Events and Eight Common Features of Excessive Rainfall for 2006-2011

  2. Outline • Background Information • Methodology • Analysis and Results • Conclusions • Future Work

  3. Background • Flash flood occurs within 6 hours of a causative event • Flood forecasts • Flash flood guidance (FFG) software from local river forecast center (RFC) • Soil conditions, estimated precipitation, river levels, and terrain • Current variable checklist is small • Improve checklist

  4. Motivation • Second-most deadly weather event in the United States • First is heat-related events • Damages and fatalities are increasing • Antecedent environmental conditions and location

  5. Hypothesis • When environmental and antecedent conditions meet the criteria of Maddox et al. (1979), a flash flood event will occur in Iowa.  

  6. Data • Archived data • Iowa Environmental Mesonet • Storm Prediction Center • NCDC (National Climatic Data Center) StormData • Wunderground • University of Wyoming soundings • AWIPS (Advanced Weather Interactive Processing System)

  7. Case Selection • Watches, Warnings, and LSRs • Ice jams • 1. Watch and warning issued, and flash flood reported • 2. Watch issued, and no flash flood reported • 3. No watch issued, and flash flood reported

  8. Cases

  9. Maddox et al. (1979) • Eight criteria • Associated with convective storms. • Surface dew points are high. • High moisture content is present throughout the layer • Weak to moderate vertical wind shear throughout the layer • Repeatedly move over the same area • Weak, mid-tropospheric, meso-α scale trough • Meso-α scale = 200-2000 km (squall lines, MCSs, tropical cyclones) • Very near the mid-tropospheric, large-scale ridge position • Occurs during the nighttime hours

  10. Results: Convective (#1) and Motion (#5) • Lightning strikes and slow motion • Case 1 (10/14/2007) • Case 3 (5/10/2008)

  11. Results: Dew Point (#2) • Threshold: Climatological average

  12. Results: Moisture (#3) • High moisture throughout layer • Moisture transport vectors, Θe, and precipitablewater • Equivalent potential temperature = total moisture and heat • Case 1 • Case 3

  13. Results: Precipitable Water (#3) • Threshold: Climatological average

  14. Results: Shear (#4) • Threshold: Weak to Moderate shear • Slower storm motion

  15. Results: Shear (#4) • Threshold: • Veering near surface • Uni-directional aloft • Increasing in magnitude with height • Case 1 (left) • Ideal Maddox (middle) • Case 3 (right)

  16. Results: Set-up (#6, #7) • Thresholds: • Weak, mid-tropospheric, meso-α scale trough • 500 mbanalysis • Mid-tropospheric, large-scale ridge position • Maddox et al (1979) ideal set-up • Double jet streaks • Strong moisture axis at all levels • Developing cyclone

  17. Results: Set-up • Case 1 • SW trough • Large-scale ridge 300 mb 500 mb Surface 850 mb

  18. Results: Set-up • Case 3 • Short-wave trough • Large-scale trough 500 mb 300 mb 850 mb Surface

  19. Results: Nighttime event (#8) • Nighttime event • 3Z to 12 Z • Low-level jet

  20. Results: Antecedent Precipitation

  21. Results: Criteria Comparison

  22. Conclusion • Moisture and forcing • Cyclone maturity and weak to moderate shear • Flood events meet more criteria

  23. Future Work • More cases • Only spring and fall events • Freezing level • Winds increase with height in radiosonde • LLJ influence

  24. References • Ashley, S. T. and W. S. Ashley, 2008: Flood Fatalities in the United States. J. Appl. Meteor. Climatol., 47, 805–818. • Ashley, W. S., 2007: Spatial and Temporal Analysis of Tornado Fatalities in the United States: 1880–2005. Wea. Forecasting, 22, 1214–1228. • Doswell, C. A., H. E. Brooks, and R. A. • Maddox, 1996: Flash Flood Forecasting: An Ingredients-Based Methodology. Wea. Forecasting, 11, 560–581. • European Space Agency, cited 2009: SMOS Scientific Objectives. [Available online at http://www.esa.int/esaLP/ESAS7C2VMOC_LPsmos_0.html.] • Funk, Theodore W., 1991: Forecasting Techniques Utilized by the Forecast Branch of the National Meteorological Center During a Major Convective Rainfall Event. Wea. Forecasting, 6, 548–564. • Junker, N. W., R. S. Schneider, and S. L. Fauver, 1999: A Study of Heavy Rainfall Events during the Great Midwest Flood of 1993. Wea. Forecasting, 14, 701–712. • Maddox, R. A., C. F. Chappell, and L. R. Hoxit, 1979: Synoptic and Meso-α Scale Aspects of Flash Flood Events1. Bull. Amer. Meteor. Soc., 60, 115–123. • Morss, Rebecca E., 2010: Interactions among Flood Predictions, Decisions, and Outcomes: Synthesis of Three Cases. Natural Hazards Review,11, 3, 83. • WFO DMX Station Duty Manual, Vol. 1, Section 5.2, 2011. • Roebber, P. J., and J. Eise, 2001: The 21 June 1997 Flood: Storm-Scale Simulations and Implications for Operational Forecasting. Wea. Forecasting, 16, 197–218

  25. Acknowledgements • Mindy Beerends • Kristie Franz

  26. Questions? Vortex Insurance Agency cited 2009. [Available online at http://www.vortexinsuranceagency.com/AboutUs/InsuranceOrDerivative.aspx.]

More Related