Forecast Evaluation and Applied Statistics

Weather Verification

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Providing meaningful information to scientific developers and operational end users

Welcome to the homepage of the Forecast Evaluation and Applied Statistics group of RAL's Joint Numerical Testbed (JNT). This group was formerly part of the Weather Systems and Assessment Program (WSAP), and was formed out of the earlier forecast verification group within RAL. The new name better reflects the wide variety of projects and activities undertaken by us; including extreme value statistical analysis applied to weather and climate data, weather modification, and the development of a state-of-the-art suite of software tools for performing forecast verification.

The page is organized into a tabbed front page giving information about: relevant software (including many software packages designed by our staff), activities of our group (as well as some related activities by other groups in the Colorado area), related links, and people. Links to pages about specific projects involving our group are given at the right along with upcoming workshops being largely organized by us.

The roots of applied statistics in RAL are in forecast verification, which is the process of determining the quality of forecasts. Below is some further information about this subject.

Statistical verification of forecasts is a critical component of their development. Improvements can be made by evaluating forecast products throughout the development process as deficiencies in the algorithms are discovered. Verification is also beneficial to forecasters and end users because verification findings supply them with objective data about the quality or accuracy of the forecasts, which can feed into decision processes (Brown, 1996).

MET -- Model Evaluation Tools

Forecast verification software initially developed for the WRF model. Developed by John Halley Gotway, Lacey Holland, Randy Bullock, David Ahijevych, Barbara Brown, Chris Davis, and Eric Gilleland

R software packages

Developed primarily by our staff include:

Extremes Toolkit (extRemes)
Graphical User Interface software for weather and climate applications of statistical extreme value analysis. Developed by Eric Gilleland, Rick Katz (ISSE), and Greg Young.

Forecast verification analysis and graphical functions. Developed by and still maintained by Matt Pocernich.

Other statistical software developed at NCAR

IMAGe Software

Other Software

Software for Extreme Value Theory: an informative web page with links originally created by Alec Stephenson, and now maintained by Eric Gilleland.

Reading Groups

The following reading groups are organized within the Forecast Evaluation and Applied Statistics group.


The following is a schedule of meetings organized in full or in part by the Forecast Evaluation and Applied Statistics group.


  • ICP Fall Workshop, 24-25 August, 2009, Boulder, Colorado.
  • DTC Verification Workshop, 26-28 April 2009, Boulder, CO.

Selected Conferences

Selected seminar presentations by our staff.



Extreme events in climate and weather an interdisciplinary workshop (10w5016), Banff Centre, Banff, Alberta, Canada, 22--27 August 2010. Gilleland, E. Some extreme value problems in climatology (pdf)

90th American Meteorological Society Annual Meeting, 16-21 January 2010, Atlanta, Georgia. Gilleland, E, D Ahijevych, BG Brown, B Casati and EE Ebert. Spatial Forecast Verification. 20 January 2010 (pdf).


The Fourth International Verification Methods Workshop. Finnish Meteorological Institute (FMI), Helsinki, Finland, 4-10 June 2009. Gilleland E, J Lindström and F Lindgren. Spatial Forecast Verification: The Image Warp. (pdf)


The 19th TIES Conference 8-13 June 2008 Kelowna, BC Canada. Gilleland E. Spatial Extremes in Atmospheric Problems (invited talk, pdf, References pdf). Lindström J, E Gilleland and F Lindgren. The Image Warp for Gridded Forecast Verification. (invited talk, ppt, pdf).


2007-08 Program on Risk Analysis, Extreme Events and Decision Theory, Opening workshop, 16-19 September, 2007, Statistical and Applied Mathematical Sciences Institute (SAMSI), Research Triangle Park, North Carolina, U.S.A. Gilleland E, Extremes and Atmospheric Data (invited talk, pdf)

Schedule of Seminars


SeminarTime/Place Presenter
Are our Air Traffic Networks Particularly Vulnerable to Spatial Hazards? (abstract)Tuesday, February, 15 at 1:30pm/FL2-1022 (Refreshments at 1:15pm)Wilkinson, Sean M.


SeminarTime/Place Presenter
Circular CAR Modeling of Vector Fields (abstract)Tuesday, November, 2 at 3:00pm/ML-ChapmanModlin, Danny


SeminarTime/Place Presenter


SeminarTime/Place Presenter
- - -
Spatio-Temporal Modeling of Precipitation Using Gaussian Markov Random Fields (abstract, pdf)Wednesday, September 17 at 1:30pm/ML-Chapman (refreshments at 1:15pm)Johan Lindström
Fast Estimation of Spatially Dependent Temporal Trends Using Gaussian Markov Random Fields (abstract, pdf)Wednesday, September 17 at 10:30am/ML-Chapman David Bolin
Between residual tail-dependence and Hüsler-Reiss triangular arrays: Tail-dependence parameters and limiting multivariate EV distributions under a new second order condition. (abstract (pdf)) Friday, July 11 at 10:00am/ML-Chapman Rolf-Dieter Reiss
Statistical interpretation of NWP model output: A survey of methodsMonday, June 16 at 10:00am/FL-MSR (FL2-1022) Laurie Wilson
Image Warping for Forecast Verification (abstract, txt)Tuesday, June 3 at 10:45am/FL-MSR (FL2-1022) Johan Lindström
High-resolution time lagged ensembles: walking the resolution-predictability tightrope (abstract, txt) Wednesday, April 23 at 3:00pm/FL-MSR (FL2-1022) Marion Mittermaier
Rainmakers, scientists and statisticians: The challenges in designing a weather modification experiment (abstract, pdf)Wednedsay, April 9 at 3:00pm/FL2-1001Matt Pocernich
A wavelet-based verification approach to account for the variation in scale representativeness of observation networks (abstract, txt) Tuesday, April 8 at 3:00pm/FL-MSR (FL2-1022) Barbara Casati

Visitor Schedule

30 July - 6 AugustBrian Ancell, Texas Tech University, Atmospheric Sciences Group, Dept. of Geosciences, Lubbock, Texas
1 June - 15 AugustChristopher Bednarczyk, Texas Tech University, Atmospheric Sciences Group, Dept. of Geosciences, Lubbock, Texas
1 June - 15 AugustRoelof Burger, University of Witwatersrand, School of Geography, Archaeology and Environmental Studies, Johannesburg, South Africa
15 August - 14 SeptemberSara Jane Lock, University of Leeds, School of Earth and Environment, Leeds, United Kingdom
15 - 26 AugustMarion Mittermeier, Mesoscale Model Development and Diagnostics Group, NWP, Met Office, United Kingdom
18 September - 1 OctoberDon Morton, University of Alaska, Arctic Region Supercomputing Center, Fairbanks, Alaska
27 June - 6 AugustEsa-Matti Tastula, University of South Florida, College of Marine Science, Saint Petersburg
17 - 23 July Marcus Walter, Cornell University, Earth and Atmospheric Sciences, Ithaca, New York/Good Morning America, New York, New York
1 - 5 November Danny Modlin, North Carolina State University, Dept. of Statistics, Raleigh, North Carolina
31 March - 27 April Barbara Casati, Ouranos Consortium on Regional Climatology and Adaptation to Climate Change, Montreal, Canada
12 - 25 April Marion Mittermaier, Mesoscale Model Development and Diagnostics Group, NWP, Met Office, United Kingdom
2 - 6 June Johan Lindström, Mathematical Statistics, Centre for Mathematical Sciences, Lund University, Lund, Sweden.
10-20 June Laurie Wilson, Science and Technology Branch, Environment Canada, Dorval, Québec, Canada.
11-15 July Rolf-Dieter Reiss, University of Siegen.
3 August - 12 October Johan Lindström, Mathematical Statistics, Centre for Mathematical Sciences, Lund University, Lund, Sweden.

Outside Seminars

The following regularly scheduled seminars are offered by other similar institutions, but are not necessarily affiliated with the Forecast Evaluation and Applied Statistics group.

Selected Publications
Refereed Papers
Non-Refereed Papers
Technical Notes
Books/Book Chapters

Refereed Papers


Gilleland, E., 2011: Spatial Forecast Verification: Baddeley's Delta Metric Applied to the ICP Test Cases, Accepted to Wea. Forecasting

Gilleland, E. and Katz, R.W., 2011: New software to analyze how extremes change over time. Eos, 11 January, 92 (2), 13--14. (pdf)


Gilleland, E., D.A. Ahijevych, B.G. Brown and E.E. Ebert, 2010: Verifying Forecasts Spatially. Bull. Amer. Meteor. Soc., October, 1365--1373.

Heaton, M.J., M. Katzfuss, S. Ramachandar, K. Pedings, E. Gilleland, E. Mannshardt-Shamseldin, and R.L. Smith, 2010: Spatio-Temporal Models for Large-scale Indicators of Extreme Weather. Accepted to Environmetrics

Gilleland, E., J. Lindström, and F. Lindgren, 2010. Analyzing the image warp forecast verification method on precipitation fields from the ICP. Wea. Forecasting, 25, (4), 1249--1262.


Abeysirigunawardena, D.S., E. Gilleland, D. Bronaugh, 2009. Extreme wind regime responses to climate variability and change in the inner-south-coast of British Columbia Canada. Atmosphere-Ocean, 47(1):41--61.

Ahijevych, D., E. Gilleland, B.G. Brown, and E.E. Ebert, 2009. Application of spatial verification methods to idealized and NWP gridded precipitation forecasts. Wea. Forecasting, 24 (6), 1485--1497.

Gilleland, E., D. Ahijevych, B.G. Brown, B. Casati, and E.E. Ebert, 2009. Intercomparison of Spatial Forecast Verification Methods. Wea. Forecasting, 24, 1416--1430, DOI: 10.1175/2009WAF2222269.1.


Gilleland E, TCM Lee, J Halley Gotway, RG Bullock, and BG Brown, 2008. Computationally efficient spatial forecast verification using Baddeley's Δ image metric. Mon. Wea. Rev. 136(5):1747--1757.

Zheng X, and RW Katz, 2008. Simulation of spatial dependence in daily rainfall using multisite generators. Water Resources Research, 44 (in press).

Zheng X, and RW Katz, 2008. Mixture model of generalized chain-dependent processes and its application to simulation of interannual variability of daily rainfall. J. Hydrology, 349:191--199.


Apipattanavis S, G Podesta, B Rajagopalan, and RW Katz, 2007. A semiparametric multivariate and multisite weather generator. Water Resources Research, 43(11): W11401, doi:10.1029/2006WR005714.

Furrer EM, and RW Katz, 2007. Generalized linear modeling approach to stochastic weather generators. Climate Research, 34:129--144.

Habib E, CG Malakpet, A Tokay, and PA Kucera, 2007. Sensitivity of streamflow simulations to temporal variabilitiy and estimation of Z-R relationships. J. Hydrologic Engineering (in review).

Harper BR, RW Katz, and RC Harriss, 2007. Statistical methods for quantifying the effect of the El Nino-Southern Oscillation on wind power in the North Great Plains of the United States. Wind Engineering, 31:123--137.

Lamptey BL, RE Pandya, TT Warner, R Boger, RT Bruintjes, PA Kucera, A Laing, MW Moncrieff, MK Ramamurthy, and TC Spangler, 2007. An Africa initiative sponsored by the University Corporation for Atmospheric Research. Bull. Amer. Meteor. Soc. (in review).


Davis CA, BG Brown, and RG Bullock, 2006a. Object-based verification of precipitation forecasts, Part I: Methodology and application to mesoscale rain areas. Mon. Wea. Rev. 134:1772--1784.

Davis CA, BG Brown, and RG Bullock, 2006b. Object-based verification of precipitation forecasts, Part II: Application to convective rain systems. Mon. Wea. Rev. 134:1785--1795.

Gilleland E and TL Fowler, 2006. Network design for verification of ceiling and visibility forecasts, Environmetrics 17(6):575--589.

Katz RW and M Ehrendorfer, 2006. Bayesian approach to decision making using ensemble weather forecasts. Weather and Forecasting, 21:220--231.


Gochis D, PA Kucera, and co-authors, 2005. Meeting summary of UCAR/NCAR Junior Faculty Forum on Future Scientific Directions: The water cycle across scales working group. Bull. Amer. Meteor. Soc. 86:1743--1746.

Gilleland E and D Nychka, 2005. Statistical Models for Monitoring and Regulating Ground-level Ozone, Environmetrics 16: 535--546.

Katz RW, GS Brush, and MB Parlange, 2005. Statistics of extremes: Modeling ecological disturbances. Ecology, 86:1124--1134.

Stephenson A and E Gilleland, 2005. Software for the Analysis of Extreme Events: The Current State and Future Directions, Extremes 8:87--109.


Kucera PA, CB Young, and WF Krajewski, 2004. Geographic Information System based studies of radar beam blockage: A case study of Guam. J. Atmos. Oceanic Technol. 24:995--1006.

Non-refereed Papers

Ahijevych DA, E Gilleland, BG Brown, EE Ebert, L Holland, and C Davis, 2008. Intercomparison of spatial verification methods. 88th Annual American Meteorological Society (AMS) meeting, New Orleans, Louisiana. 9.1 Probability/Statistics conference.

Gilleland E and RW Katz. "Analyzing seasonal to interannual extreme weather and climate variability with the extremes toolkit (extRemes)", 18th Conference on Climate Variability and Change, 86th American Meteorological Society (AMS) Annual Meeting, 29 January - 2 February, 2006, Atlanta, Georgia. P2.15

Technical Notes

Gilleland, E., L. Chen, M. DePersio, G. Do, K. Eilertson, Y. Jin, E.L. Kang, F. Lindgren, J. Lindström, R.L. Smith, and C. Xia, 2011. Spatial Forecast Verification: Image Warping. NCAR Technical Note, TN-482+STR, 30pp. (to appear)

Gilleland E, 2008. Confidence intervals for forecast verification. Submitted to NCAR Technical Notes (pdf)

Books and Book Chapters

Gilleland E, D Nychka, and U Schneider, 2006. Spatial models for the distribution of extremes, Hierarchical modelling for the Environmental Sciences: statistical methods and applications, Edited by JS Clark and A Gelfand. Oxford University Press, New York pp.170--183. ISBN 0-19-8569671

Note: full phone: 303 - 497 - XXXX | email addresses end in ""

Staff and Primary Contacts

  • BROWN, Barbara | PROJ SCIENTIST III | ph: 8468 | email: bgb
  • NEWMAN, Kathryn | ASSOC SCIENTIST III | ph: 2741 | email: knewman



(See Activities Tab)