TORNADOES: PAST, PRESENT, AND FUTURE

Transcription

1 TORNADOES: PAST, PRESENT, AND FUTURE VICTOR GENSINI, PH.D. ASSOCIATE PROFESSOR METEOROLOGY PROGRAM COLLEGE OF DUPAGE (NEXLAB) GLEN ELLYN, THIS RESEARCH AIMS TO OBJECTIVELY RECONSTRUCT HAZARDOUS CONVECTIVE WEATHER IN THE UNITED STATES AND PROJECT POTENTIAL CHANGES IN A FUTURE CLIMATE AS SIMULATED BY A GLOBAL CLIMATE MODEL. 14 FEBRUARY 2017 NATIONAL TORNADO SUMMIT 1 Global Temperature (Land and Ocean) Temperature Anomaly = Hansen et al. (2001) Image courtesy of Dr. Walker Ashley MOTIVATION WHAT MAY HAPPEN TO FUTURE SEVERE WEATHER ACTIVITY IF BUSINESS-AS-USUAL EMISSIONS CONTINUE? PAST PRESENT FUTURE 1

2 PAST REPORTS HAVE CAVEATS INGREDIENTS BASED APPROACH Apples Sugar Flour Egg Shear of the vertical wind Lift Instability Moisture Tippett, M. K., J. T. Allen, V. A. Gensini, and H. E. Brooks, 2015: Climate and hazardous convective weather. Cur. Climate Change Rep. DOI: /s Doswell, C.A. III, H.E. Brooks and R.A. Maddox (1996): Flash flood forecasting: An ingredientsbased methodology. Wea. Forecasting, 11, ENVIRONMENTAL APPROACH GLOBAL TORNADO ENVIRONMENTS Brooks, H. E., J. W. Lee, and J. P. Craven, 2003: The spatial distribution of severe thunderstorm and tornado environments from global reanalysis data. Atmos. Res., 67-68, Updated by Gensini (2014) from Brooks, H. E., J. W. Lee, and J. P. Craven, 2003: The spatial distribution of severe thunderstorm and tornado environments from global reanalysis data. Atmos. Res., 67-68,

3 23 June April May 2013 WHAT HAS THE PAST TOLD US ABOUT TORNADOES? PEOPLE IN NEBRASKA FILM TORNADOES WITHOUT WEARING PANTS TORNADO REPORTS ARE NOT A RELIABLE METRIC NO SIGNIFICANT TREND IN ENVIRONMENTS TO THIS POINT SLIGHT INCREASE IN INTERANNUAL VARIABILITY Gensini, V. A., and W. S. Ashley, 2011: Climatology of potentially severe convective environments from the North American regional reanalysis. Electronic J. Severe Storms Meteor., 6 (8), TORNADO FORECASTS PRESENT % 3000 Total F0-F1 F2-F3 F4-F5 80.0% 70.0% Fatalities By Decade % 50.0% 40.0% 30.0% 20.0% Percentage of Fatalities by F-Scale % 0 0.0%

4 NATIONAL WEATHER SERVICE (W-E-A) Make shelters great again! TORNADO SENSATIONALISM 4

5 May 20, 2013 Moore, OK EF5, 24 fatalities, 246 injuries Humans modify the local environment! More so now than *ever* before! The Expanding Bull s-eye Effect Ashley, W. S., S. Strader, T. Rosencrants, and A. J. Krmenec, 2014: Spatiotemporal changes in tornado hazard exposure: The case of the expanding bull's eye effect in Chicago, IL. Weather, Climate, and Society, 6,

6 WHAT HAS THE PRESENT TOLD US ABOUT TORNADOES? OUR FORECASTS ARE GETTING BETTER BUT, HAVE WE HIT A CRITICAL POINT? EXPOSURE & VULNERABILITY ARE KEY FUTURE JUST WHEN YOU THINK WHAT HAS/WILL HAPPEN(ED) TO SEVERE STORMS? SPATIO-TEMPORAL FREQUENCY INTENSITY Trapp et al. (2007)? Jan Dec Gensini et al. (2013) Diffenbaugh et al. (2013) DYNAMICAL DOWNSCALING DYNAMICAL DOWNSCALING Advantages Disadvantages Can resolve climate variables on scales not resolvable by GCMs or RCMs Only as good as current microphysics (i.e., still a model!) Work in this area for purposes of severe weather is relatively new. -Severe Convection needs to be below 4km grid spacing. Customizable for stakeholder Takes on biases of parent model Computationally expensive Gensini, V. A., and T. L. Mote, 2015: Downscaled estimates of late 21st century severe weather from CCSM3. Climatic Change, 129, Gensini, V. A., and T. L. Mote, 2014: Estimations of hazardous convective weather in the United States using dynamical downscaling. J. Climate, 27, Trapp, R. J., E. Robinson, M. Baldwin, N. Diffenbaugh, and B. Schwedler, 2011: Regional climate of hazardous convective weather through high-resolution dynamical downscaling. Climate Dyn.,37, Helps verify or refute statistical downscaling 6

7 INTRODUCTION PAST PRESENT FUTURE GWO/PREDICTION March May 2090 WHAT MAY THE FUTURE HOLD FOR TORNADOES? GREATER NUMBER OF ENVIRONMENTS Z > 50 dbz Early season (March) shows largest increase ALSO AN INCREASE IN VARIABILITY EXPOSURE & VULNERABILITY ARE STILL KEY JUST WHEN YOU THINK 7

8 SPRINGTIME TORNADOES AND THE GLOBAL WIND OSCILLATION (SUBSEASONAL PREDICTION OF TORNADOES) Gensini, V. A., and A. J. Marinaro, 2015: Tornado activity in the United States related to global relative angular momentum. Mon. Wea. Rev., 144, WHAT IS THE GLOBAL WIND OSCILLATION (GWO)? AAM sink through -frictional & mountain torque Meridional momentum transport AAM source through + frictional torque More info on github: Westerlies Trades 8

9 resulting in broad zonal Pacific Jet. Meridional momentum transport Meridional momentum transport It s the subsequent extension and breakdown of this jet into the western CONUS that forecasters can/should anticipate. Westerlies Westerlies Trades Trades TORNADOES BY GWO PHASE ~1 F2/Day ~1 F3/ 3 Days ~1 F2/ 13 Days ~1 F3/ 34 Days 9

10 SPATIAL PLOTS 10

11 PHASE SPACE March-June F/EF March-June F/EF1 11

12 Decreasing M R - Torque +Africa +PNA Pattern F2 ~8x less likely Mar-May 2011 Mar-May 2013 F2 ~3x less likely DY14 DY7 F2 ~15x more likely DY28 Start Increasing M R + Torque +E. Indian Ocean -PNA Pattern March-June F/EF2 Mar-May 2011 Mar-May 2013 ~60 day orbit in 2016 Mar 75 Apr 758 May 326 TOTAL Tornadoes - 1,195 Mar 18 Apr 86 May 267 TOTAL Tornadoes PLOTS AVAILABLE AT: SUMMARY ABOVE PHASES BELOW PHASES AMPLITUDE, EFFICIENCY WHERE DO WE GO FROM HERE? 12

13 POTENTIAL PRODUCT? Forecasts issued on Sunday evening for Weeks 2 and 3. In the process of creating forecast tools Join us! INTRODUCTION PAST PRESENT FUTURE GWO/PREDICTION THANKS! More info: weather.cod.edu/~vgensini gensiniwx.com 13