Recent Trends in Four Common Stability Indices Derived from U.S. Radiosonde Observations

Diana DeRubertis Department of Geography, University of California, Berkeley, Berkeley, California

Search for other papers by Diana DeRubertis in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

Daily sounding-derived atmospheric stability indices are typically employed for short-term severe weather forecasts. Over longer time periods, these indicators may convey changes in the potential for severe storm development over the United States. Daily (0000 UTC) observations from 48 radiosonde stations in the contiguous United States are extracted to assemble a ∼50 yr record of four common stability indices: the Lifted Index, the K-Index, convective available potential energy (CAPE), and the Air Force Severe Weather Threat Index. Because of radiosonde data inhomogeneities, the 1973–97 period is the focus of the analysis. Trends in the mean and extreme values of daily index observations are calculated for spring and summer seasons. In addition, climatological mean indices, as well as the mean frequency of index extremes, are determined for all U.S. regions. At stations free of obvious data discontinuities, the early part of the record (1948–65) is compared with more recent periods.

In spring, few significant changes in either index means or extremes are reported. However, in summer, widespread trends toward enhanced instability appear, particularly in the Lifted Index, the K-Index, and CAPE. Stations in the Plains and southern states show the most consistent increases in severe weather potential, while significant trends in index extremes are uncommon in the western region, possibly due to the rarity of severe weather there.

Corresponding author address: Dr. Diana DeRubertis, 2195 Station Village Way, Apt. #1117, San Diego, CA 92108-6516. Email: diana.derubertis@gmail.com

Abstract

Daily sounding-derived atmospheric stability indices are typically employed for short-term severe weather forecasts. Over longer time periods, these indicators may convey changes in the potential for severe storm development over the United States. Daily (0000 UTC) observations from 48 radiosonde stations in the contiguous United States are extracted to assemble a ∼50 yr record of four common stability indices: the Lifted Index, the K-Index, convective available potential energy (CAPE), and the Air Force Severe Weather Threat Index. Because of radiosonde data inhomogeneities, the 1973–97 period is the focus of the analysis. Trends in the mean and extreme values of daily index observations are calculated for spring and summer seasons. In addition, climatological mean indices, as well as the mean frequency of index extremes, are determined for all U.S. regions. At stations free of obvious data discontinuities, the early part of the record (1948–65) is compared with more recent periods.

In spring, few significant changes in either index means or extremes are reported. However, in summer, widespread trends toward enhanced instability appear, particularly in the Lifted Index, the K-Index, and CAPE. Stations in the Plains and southern states show the most consistent increases in severe weather potential, while significant trends in index extremes are uncommon in the western region, possibly due to the rarity of severe weather there.

Corresponding author address: Dr. Diana DeRubertis, 2195 Station Village Way, Apt. #1117, San Diego, CA 92108-6516. Email: diana.derubertis@gmail.com

Save
  • Angell, J. K., W. P. Elliott, and M. E. Smith, 1984: Tropospheric humidity variations at Brownsville, Texas and Great Falls, Montana, 1958–80. J. Climate Appl. Meteor., 23 , 12861295.

    • Search Google Scholar
    • Export Citation
  • Bluestein, H. B., 1993: Synoptic-Dynamic Meteorology in Midlatitudes. Vol. 2, Oxford University Press, 594 pp.

  • Braun, S. A., and J. P. Monteverdi, 1991: An analysis of mesocyclone-induced tornado occurrence in northern California. Wea. Forecasting, 6 , 1331.

    • Search Google Scholar
    • Export Citation
  • Changnon, S. A., 2001a: Damaging thunderstorm activity in the United States. Bull. Amer. Meteor. Soc., 82 , 597608.

  • Changnon, S. A., 2001b: Thunderstorms Across the Nation. Changnon Climatologist, 93 pp.

  • Changnon, S. A., 2001c: Thunderstorm rainfall in the coterminous United States. Bull. Amer. Meteor. Soc., 82 , 19251940.

  • David, C. L., 1976: A study of upper air parameters at the time of tornadoes. Mon. Wea. Rev., 104 , 546551.

  • Davis, R. E., T. M. Stanmeyer, and G. V. Jones, 1997: A synoptic climatology of tornadoes in Virginia. Phys. Geogr., 18 , 383407.

  • DeGaetano, A. T., and R. J. Allen, 2002: Trends in twentieth-century temperature extremes across the United States. J. Climate, 15 , 31883205.

    • Search Google Scholar
    • Export Citation
  • Easterling, D. R., J. L. Evans, P. Groisman, T. R. Karl, K. E. Kunkel, and P. Ambenje, 2000: Observed variability and trends in extreme climate events. Bull. Amer. Meteor. Soc., 81 , 417426.

    • Search Google Scholar
    • Export Citation
  • Elliott, W. P., and D. J. Gaffen, 1991: On the utility of radiosonde humidity archives for climate studies. Bull. Amer. Meteor. Soc., 72 , 15071520.

    • Search Google Scholar
    • Export Citation
  • Gaffen, D. J., 1993: Historical changes in radiosonde instruments and practices. Rep. 50, WMO/TD- No. 541, World Meteorological Organization, 123 pp.

  • Gaffen, D. J., 1994: Temporal inhomogeneities in radiosonde temperature records. J. Geophys. Res., 99 , 36673676.

  • Gaffen, D. J., and R. J. Ross, 1999: Climatology and trends of U.S. surface humidity and temperature. J. Climate, 12 , 811828.

  • Galway, J. G., 1956: The lifted index as a predictor of latent instability. Bull. Amer. Meteor. Soc., 37 , 528529.

  • George, J. J., 1960: Weather and Forecasting for Aeronautics. Academic Press, 673 pp.

  • Giordano, L. A., 1994: A fingertip guide to key stability and shear index values used in evaluating severe weather and flash flood potential. National Weather Service Eastern Region, ERH Tech. Attachment 94-4, 7 pp.

  • Gordon, J. D., and D. Albert, 2000: A comprehensive severe weather checklist and forecast guide. National Weather Service Central Region, NWS Tech. Service Publication TSP-10.

  • Grazulis, T. P., 1993: A 110-year perspective of significant tornadoes. The Tornado: Its Structure, Dynamics, Prediction and Hazards, Geophys. Monogr., No. 79, Amer. Geophys. Union, 467–478.

  • Hales, J. E., 1985: Synoptic features associated with Los Angeles tornado occurrence. Bull. Amer. Meteor. Soc., 66 , 657662.

  • Hoaglin, D., F. Mosteller, and J. Tukey, 1983: Understanding Robust and Exploratory Data Analysis. Wiley, 527 pp.

  • Houghton, J. T., Y. Ding, D. J. Griggs, M. Noguer, P. J. van der Linden, X. Dai, K. Maskell, and C. A. Johnson, 2001: Climate Change 2001: The Scientific Basis. Cambridge University Press, 881 pp.

    • Search Google Scholar
    • Export Citation
  • Johns, R. H., J. M. Davies, and P. W. Leftwich, 1993: Some wind and instability parameters associated with strong and violent tornadoes, part II. The Tornado: Its Structure, Dynamics, Predictions and Hazards, Geophy. Monogr., No. 79, Amer. Geophys. Union, 583–590.

  • Jones, P. D., T. J. Osborn, K. R. Briffa, C. K. Folland, E. B. Horton, L. V. Alexander, D. E. Parker, and N. A. Rayner, 2001: Adjusting for sampling density in grid-box land and ocean surface temperature time series. J. Geophys. Res., 106 , 33713380.

    • Search Google Scholar
    • Export Citation
  • Karl, T. R., N. Nicholls, and A. Ghazi, 1999: Weather and Climate Extremes:. Changes, Variations, and a Perspective from the Insurance Industry. Kluwer Academic, 349 pp.

    • Search Google Scholar
    • Export Citation
  • Kelly, D. L., J. T. Schaefer, and C. A. Doswell, 1985: Climatology of nontornadic severe thunderstorm events in the United States. Mon. Wea. Rev., 113 , 19972014.

    • Search Google Scholar
    • Export Citation
  • Lanzante, J. R., 1996: Resistant, robust and non-parametric techniques in the analysis of climate data: Theory and examples, including applications to historical radiosonde station data. Int. J. Climatol., 16 , 11971226.

    • Search Google Scholar
    • Export Citation
  • Lau, K-M., J-Y. Lee, K-M. Kim, and I-S. Kang, 2004: The North Pacific as a regulator of summertime climate over Eurasia and North America. J. Climate, 17 , 819833.

    • Search Google Scholar
    • Export Citation
  • Lehmann, E. L., 1975: Nonparametrics: Statistical Methods Based on Ranks. Holden-Day, 457 pp.

  • Meehl, G. A., and Coauthors, 2000: An introduction to trends in extreme weather and climate events: Observations, socioeconomic impacts, terrestrial ecological impacts, and model projections. Bull. Amer. Meteor. Soc., 81 , 413416.

    • Search Google Scholar
    • Export Citation
  • Miller, R. C., 1972: Notes on analysis and severe-storm forecasting procedures of the Military Warning Center. Air Weather Service (MAC), Tech. Rep. 200, Scott Air Force Base, IL, 181 pp.

  • Rasmussen, E. N., and D. O. Blanchard, 1998: A baseline climatology of sounding-derived supercell and tornado forecast parameters. Wea. Forecasting, 13 , 11481164.

    • Search Google Scholar
    • Export Citation
  • Robertson, A. W., and M. Ghil, 1999: Large-scale weather regime and local climate over the western United States. J. Climate, 12 , 17961813.

    • Search Google Scholar
    • Export Citation
  • Ross, R. J., and W. P. Elliott, 2001: Radiosonde-based Northern Hemisphere tropospheric water vapor trends. J. Climate, 14 , 16021612.

    • Search Google Scholar
    • Export Citation
  • Schaefer, J. T., and J. G. Galway, 1982: Population biases in the tornado climatology. Preprints, 12th Conf. on Severe Local Storms, San Antonio, TX, Amer. Meteor. Soc., 51–54.

  • Schultz, P., 1989: Relationship of several stability indices to convective weather events in northeast Colorado. Wea. Forecasting, 4 , 7380.

    • Search Google Scholar
    • Export Citation
  • Trenberth, K. E., and J. W. Hurrell, 1994: Decadal atmosphere-ocean variations in the Pacific. Climate Dyn., 9 , 303319.

  • Wilks, D. S., 1995: : Statistical Methods in the Atmospheric Sciences. Academic Press, 467 pp.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 940 279 33
PDF Downloads 853 237 35