1. 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

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 CaseStart (UTC)End (UTC)Flood Event Watch 110/14/2007 21:00 10/15/2007 8:48Yes 24/25/2008 2:004/25/2008 16:53Yes 35/11/2008 0:005/11/2008 8:57NoYes 47/7/2010 8:007/7/2010 18:00YesNo 58/9/2010 3:008/10/2010 15:00YesNo 65/25/2011 8:005/26/2011 2:20NoYes

9. Maddox et al. (1979)  Eight criteria 1. Associated with convective storms. 2. Surface dew points are high. 3. High moisture content is present throughout the layer 4. Weak to moderate vertical wind shear throughout the layer 5. Repeatedly move over the same area 6. Weak, mid-tropospheric, meso- α scale trough  Meso- α scale = 200-2000 km (squall lines, MCSs, tropical cyclones) 7. Very near the mid-tropospheric, large-scale ridge position 8. 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 CaseT d Climate Avg (˚F) 14 Oct 2007 42.6 25 Apr 2008 41.5 10 May 2008 46.1 7 Jul 2010 64.3 9 Aug 2010 64.2 25 May 2011 52.0

12. Results: Moisture (#3)  High moisture throughout layer  Moisture transport vectors, Θ e, and precipitable water  Equivalent potential temperature = total moisture and heat  Case 1  Case 3

13. Results: Precipitable Water (#3)  Threshold: Climatological average CasePwat Climate Avg (in.) 14 Oct 2007 0.53 25 Apr 2008 0.75 10 May 2008 0.93 7 Jul 20101.22 9 Aug 2010 1.1 25 May 2011 1.06

14. Results: Shear (#4)  Threshold: Weak to Moderate shear  Slower storm motion CriteriaThreshold 0-1 km shear < 12 kts 0-6 km shear < 35 kts Effective shear < 25 kts

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 mb analysis  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 850 mb Surface 500 mb 300 mb

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

20. Results: Antecedent Precipitation

21. Results: Criteria Comparison CaseFlood EventConvectiveDew PointMoisture Content 1YesXXX 2 XXX 3NoX 4YesXXX 5 XXX 6NoXX CaseVertical shearSame AreaSW Trough RidgeNight 1XXXX 2XX X 3 X X 4XX X 5XX XX 6 X

22. Conclusion  Moisture and forcing  Cyclone maturity and weak to moderate shear  Flood events meet more criteria CaseFlood Event Watch Criteria Met 1Yes 7 2 6 3NoYes 3 4 No 6 5YesNo 7 6 Yes 3

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 Events 1. 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.] http://www.vortexinsuranceagency.com/AboutUs/InsuranceOrDerivative.aspx