Timothy Hewson

Principal Scientist
Forecast Department, Evaluation Section, Forecast Performance and Products

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Tim Hewson leads the team responsible for "Forecast Performance Monitoring" and "Product Development" at ECMWF. As such his primary roles are leading the creation of new types of forecast chart, mainly for forecasters, and managing the production of the "Forecast Daily Report". This report is a high-profile internal document that summarises important aspects of the real-time analyses and forecasts of ECMWF's operational models. It aims to bridge the gap between forecast users and model developers in the Research Department, and is pivotal in paving the way for user-related modelling issues to be resolved.

Previously Tim was a Met Office Chief Forecaster, who carried out various related R&D roles alongside. Indeed At ECMWF he also continues to be involved in wide-ranging internal and external research initiatives.

Professional interests: 
  • Real-time assessment of forecast model performance
  • Invention of new types of forecast chart; optimising the use of colour
  • Mathematical-graphical representation of meteorological features (e.g. fronts, jet streams)
  • Statistical downscaling of model output (rainfall in particular)
  • Understanding and predicting all types of severe weather (notably windstorms in the extra-tropics)
  • Extra-tropical cyclones
  • Predictability at all lead times
  • Training forecast users
  • Collaborative project work - Technical University of Munich (3D graphical display, W2W), University of Bergen (air-sea interaction: UNPACC), University of Geneva (precipitation downscaling, ANYWHERE)
Career background: 
  • Principal Scientist and Team Leader, Forecast Department, ECMWF, 2013-present
  • Senior Scientist (consultant), Operations Department, ECMWF, 2009-2012
  • Chief Forecaster/Researcher, Met Office, Exeter. 2004-2009
  • Sabbatical from Met Office, SUNY, Albany, USA. 2004
  • Research Scientist, Joint Centre for Mesoscale Meteorology (Met Office), Reading University, and Met Office HQ, Bracknell and Exeter, 1990-2003
External recognitions: 
  • Atmospheric Science Letters Annual Editor's award 2016 (for outstanding refereeing)
  • Runner up in the Harry Otten Prize for Innovation in Meteorology - 2015 ("A Global Approach to Predicting Flash Floods")
  • Geophysical Research Letters Editor's Award 2011 (for excellence in refereeing)
  • ECMWF representative on the Working Group for Co-operation between European Forecasters (WGCEF, a EUMETNET initiative)
  • ECMWF representative on the Programme and Science Committee for the European Meteorological Society (EMS)
  • Member of the Royal Meteorological Society



Peer Reviewed Publications

Gascón, E, Hewson, T., Haiden, T. Improving Predictions of Precipitation Type at the Surface: Description and Verification of Two New Products from the ECMWF Ensemble. Wea Forecasting. In press Nov 2017.

Kern, M., Hewson, T., Sadlo, F., Westermann R., Rautenhaus. 2018 (early online release available). Robust Detection and Visualization of Jet-stream Core Lines in Atmospheric Flow. M. IEEE Transactions on Visualization and Computer Graphics 2018. Issue 99. Pp 10.

Frame, T., Harrison, G., Hewson, T., Roberts, N. 2017. Meteorological Risk: extra-tropical cyclones, tropical cyclones and convective storms. Ch. 3.7 in “Science for Disaster Risk Management”. European Commission. Eds: Poljanšek, K., Ferrer, M. M., De Groeve, T., Clark, I. Pp 551.

Swinbank, R., M. Kyouda, P. Buchanan, L. Froude, T.M. Hamill, T.D. Hewson, J.H. Keller, M. Matsueda, J. Methven, F. Pappenberger, M. Scheuerer, H.A. Titley, L. Wilson, and M. Yamaguchi, 2016: The TIGGE Project and Its Achievements. Bull. Amer. Meteor. Soc., 97, 49–67, https://doi.org/10.1175/BAMS-D-13-00191.1

Heizenreder, D., Joe, P., Hewson, T., Wilson, L., Davies, P., de Coning, E. 2015. Development of Applications towards a High Impact Weather Forecast System. Ch. 22 in “Seamless Prediction of the Earth System: From Minutes to Months”. World Meteorological Organisation. Eds: Brunet, G., Jones, S., Ruti. P. Pp 471.

Hewson, T.D. and Neu, U. 2015. Cyclones, Windstorms and the IMILAST project. Tellus A. 67, 27128. http://dx.doi.org/10.3402/tellusa.v67.27128

Neu, U., Akperov, M.G., Bellenbaum, N., Benestad, R., Blender, R., Caballero, R., Cocozza, A., Dacre, H. F., Feng, Y., Fraedrich, K.,  Grieger, J., Gulev, S., Hanley, J., Hewson, T., Inatsu, M., Keay, K., Kew, S.F., Kindem, I., Leckebusch, G.C., Liberato, M. L. R, Lionello, P., Mokhov, I. I., Pinto, J. G., Raible, C. C., Reale, M., Rudeva, I., Schuster, M., Simmonds, I., Sinclair, M., Sprenger, M.,  Tilinina, N. D., Trigo, I. F., Ulbrich, S., Ulbrich, U., Wang, X. L., Wernli, H. 2013. “IMILAST – a community effort to intercompare extratropical cyclone detection and tracking algorithms: assessing method-related uncertainties” Bull. Amer. Meteorol. Soc. 94, 529–547.

Young, M.V. and Hewson, T.D., 2012. “The forecasting challenge of waving cold fronts: Benefits of the ensemble approach” Weather. 67, 296–301.

Haiden, T., Rodwell, M.J., Richardson, D.S., Okagaki, A., Robinson, T., Hewson, T. D. 2012: “Intercomparison of Global Model Precipitation Forecast Skill in 2010/11 Using the SEEPS Score” Mon. Wea. Rev., 140, 2720–2733.

Rodwell, M. J., Richardson, D. S., Hewson, T. D. and Haiden, T.  2010. “A new equitable score suitable for verifying precipitation in numerical weather prediction” Q. J. R. Meteorol. Soc., 136: 1344–1363.

Hewson, T.D. & H.A. Titley, 2010: “Objective identification, typing and tracking of the complete life-cycles of cyclonic features at high spatial resolution” Meteorol. Appl., 17, 355-381.

Hewson, T.D., 2009: “Diminutive frontal waves - A link between fronts and cyclones” J. Atmos. Sci., 66, 116-132.

Berry, G., Thorncroft, C.D., Hewson, T.D. 2007. "African Easterly Waves during 2004 - Analysis Using Objective Techniques" Mon. Wea. Rev. 135. 1251-1267.

Carroll, E.B. and Hewson, T.D. 2005. "NWP Grid Editing at the Met Office" Wea. Forecasting. 20. 1021-1033.

Deveson, A.C.L, Browning, K.A. and Hewson, T.D. 2002. "A classication of FASTEX cyclones using a height-attributable quasi-geostrophic vertical-motion diagnostic" Q. J. R. Meteorol. Soc. 128. 93-117.

Hewson, T.D., Craig, G.C. and Claud, C. 2000. "Evolution and mesoscale structure of a polar low outbreak" Q. J. R. Meteorol. Soc. 126. 1031-1063.

Joly, A., Hewson, T.D. and others. 1999. "Overview of the field phase of the Fronts and Atlantic Storm-Track Experiment (FASTEX) project" Q. J. R. Meteorol. Soc. 125. 3131-3163.

Hewson, T.D. 1998. "Objective Fronts" Meteorol. Appl. 5. 37-65.

Hewson, T.D. 1997. "Objective Identification of Frontal Wave Cyclones" Meteorol. Appl. 4. 311-315.

Hewson, T.D. 1997. "Case Work during the Summer Study Week on Extra-Tropical Cyclones" Meteorol. Appl. 4. 375-378.

Browning, K.A., Clough, S.A., Davitt, C.S.A., Roberts, N.M., Hewson, T.D. and Healey, P.G.W. 1995. "Observations of the mesoscale sub-structure in the cold air of a developing frontal cyclone" Q. J. R. Meteorol. Soc. 121. 1229-1254.

Hewson, T.D. and Gait, N.J. 1992 "Hoar Frost Deposition on Roads" Meteorol. Mag. 121. 1-21.

Hewson, T.D. 1991. "Temperature Predictions for the UK Winter" Meteorol. Mag. 120. 1-11.


Other Publications

Pillosu, F. and Hewson, T. 2017. New point-rainfall forecasts for flash flood prediction. ECMWF Newsletter No. 153. 4-5.

Hewson, T. Use and verification of ECMWF products in Member and Co-operating States (2016). 2017. Technical Memorandum 797. ECMWF.

Haiden, T., Hewson, T., Janousek, M., Richardson, D. 2016. Forecast Performance 2015. ECMWF Newsletter No. 146. 5-6.

Richardson, D. Zsoter, E., Magnusson, L. Hewson, T., Rabier, F. 2015. Forecasts for US east coast snow storm in January 2015. 2015. ECMWF Newsletter No. 143. 6-7.

Magnusson, L., Hewson, T. Forecasts for a fatal blizzard in Nepal in October 2014. 2015. ECMWF Newsletter No. 142. 8.

Hewson, T.D., Magnusson, L., Breivik, O., Prates, F., Tsonevsky, I., de Vries, H. (J.W.). 2014. Windstorms in northwest Europe in late 2013. ECMWF Newsletter, No 139, 122-128.

Forbes, R., Tsonevsky, I., Hewson, T., Leutbecher, M. Towards predicting high-impact freezing rain events. 2014. ECMWF Newsletter. No. 141, 15-21.

Haiden, T., Bauer, P., Bidlot, J.-R., Ferranti, L. Hewson, T., Prates, F., Richardson, D.S., Vitart, F. Evaluation of ECMWF forecasts, including 2013-2014 upgrades. 2014. Technical Memorandum 742. ECMWF.

T. Haiden, L. Magnusson, I. Tsonevsky, F. Wetterhall, L. Alfieri, F. Pappenberger, P. De Rosnay, J. Munoz-Sabater, G. Balsamo, C. Albergel, R. Forbes, T. Hewson, S. Malardel, D.S. Richardson. 2014. ECMWF forecast performance during the June 2013 flood in Central Europe. Technical Memorandum 723. ECMWF.

D.S. Richardson, J.-R. Bidlot, L. Ferranti, A Ghelli, T. Haiden, T. Hewson, M. Janousek, F. Prates, F. Vitart. 2012. Verification statistics and evaluations of ECMWF forecasts in 2011-2012. Technical Memorandum 688. ECMWF.

Haiden, T. M. Rodwell, D.S. Richardson, A. Okagaki, T. Robinson, T. Hewson. 2012. Intercomparison of global model precipitation forecast skill in 2010/11 using the SEEPS score. Technical Memorandum 665. ECMWF.

D.S. Richardson, J.-R. Bidlot, L. Ferranti, A Ghelli, T. Haiden, T. Hewson, M. Janousek, F. Prates, F. Vitart. 2011. Verification statistics and evaluations of ECMWF forecasts in 2010-2011. Technical Memorandum 654. ECMWF.

M. Rodwell, T. Jung, P. Bechtold, P. Berrisford, N. Bormann, C. Cardinali, L. Ferranti, T. Hewson, F. Molteni, N.P. Wedi, M. Alonso Balmaseda, G. Balsamo, M. Bonavita, R Buizza, M. Dahoui, A. Garcia-Mendez, M. Leutbecher, P. Lopez, Y. Trémolet, F. Vitart. 2010. Developments in diagnostics research. Technical Memorandum 637. ECMWF.

D.S. Richardson, J.-R. Bidlot, L. Ferranti, A Ghelli, T. Hewson, M. Janousek, F. Prates, F. Vitart. 2010. Verification statistics and evaluations of ECMWF forecasts in 2009-2010. Technical Memorandum 635. ECMWF.

Stephenson, D.B, I.T. Jolliffe, C.A.T. Ferro, C.A. Wilson, M. Sharpe, M. Mittermaier, and T.D. Hewson, 2010: “White Paper Review on the Verification of Warnings” Met Office Forecasting Research Technical Report No. 546, 22 pp.

Hewson, T.D., 2009: “Tracking fronts and extra-tropical cyclones” ECMWF Newsletter, No. 121, 9-19.

D.S. Richardson, J.-R. Bidlot, L. Ferranti, A Ghelli, C. Gibert, T. Hewson, M. Janousek andF. Prates, F. Vitart. 2009. Verification statistics and evaluations of ECMWF forecasts in 2008-2009. Technical Memorandum 606. ECMWF.

Hewson, T.D. 2009. Forecast Product Development at ECMWF. In proceedings of the Twelfth Workshop on Meteorological Operational Systems, 2-6 November 2009. ECMWF, Reading, UK.

Hewson, T.D. 2006. "New Approaches to Verifying Forecasts of Hazardous Weather" Extended abstract for the 2nd THORPEX International Science Symposium, held in Landshut, Germany.

Watkin, H.A. and Hewson, T.D. 2006. "The Development of Feature-based Diagnostics to assess TIGGE handling of High-impact extra-tropical Cyclones" Extended abstract for the 2nd THORPEX International Science Symposium, held in Landshut, Germany.

Hewson, T.D. and Semple, A.T. 2005. "A UK Met Office perspective on the influences of extra-tropical transition on operational forecasts" Extended abstract for the 3rd international conference on Extra-Tropical transition held in Perth, Australia.

Hewson, T.D., 2004. "The value of field modifications in forecasting" Forecasting Research Technical Report no 437. Met Office.

Hewson, T.D., 2002. "A comparison of Cyclone Spectra in forecasts from the Operational (G1) and New Dynamics trial (NT) versions of the unified model - Aug to Dec 2001" Forecasting Research Technical Report no 376. Met Office.

Hewson, T.D., 2001. "The North Sea Storm of 30th October 2000" Weather. 56. 115-116.

Hewson, T.D., 1998. "A Frontal Wave Database". JCMM Internal Report No. 85. Met Office. pp 20.

Clough, S.A., Lean, H.W., Roberts, N.M., Birkett, H., Chaboureau, J-P., Dixon, R., Griffiths, M., Hewson, T.D., Montani, A. 1998. "A JCMM overview of FASTEX IOPs". JCMM Internal Report No. 81. Met Office. pp 63..

Hewson, T.D. 1993. "The fronts 92 experiment : A quicklook atlas" JCMM Internal Report No. 15. Met Office. pp 176.

Hewson, T.D. 1993. "Infrared imagery showing upper level waves - 3 May 1993" Meteorol. Mag. 122. 280-281.

Hewson, T.D. 1993. "Orographic cirrus generated by Iceland and the Faeroe Islands - 4-6 May 1993" Meteorol. Mag. 122. 249-253.

Hewson, T.D. 1993. "Infrared imagery showing cloud evolution in a record(?) Atlantic low - 9/10 January 1993" Meteorol. Mag. 122. 94-96.

Hewson, T.D. 1993. "Thunderstorm activity in a developing cyclone - 4 January 1993" Meteorol. Mag. 122. 96-98.

Hewson, T.D. 1993. "Thunderstorms and a gust front - 9 August 1992" Meteorol. Mag. 122. 18-20.

Hewson, T.D. 1992. "Infrared image of a cloud head - 27 April 1992 at 1800 UTC" Meteorol. Mag. 121. 244.



thumbnail photo of Timothy Hewson
Contact Details:
timothy . hewsonecmwf . int