What's New:

8 June 2018: The most recent version of HAILCAST is now available as part of WRFV4.0.

1 June 2017: An updated version of HAILCAST is now available that uses an adiabatic cloud water profile instead of the CAM cloud water profile to account for precipitation scavenging by insufficiently resolved bounded weak echo regions. The ability to select the timestep interval at which HAILCAST runs within WRF was also added.

17 April 2017: Updated HAILCAST released as an independent module as part of WRFV3.9. Updates include parameterized horizontal motion, embryo sizes and insertion points pegged to observations, and linear ice-collection efficiency function.

14 April 2014: HAILCAST initially released as part of the AFWA diagnostics model in WRFV3.6.1.

Description:

HAILCAST is a one-dimensional, physically-based hail forecasting model. It is a revised version of the coupled cloud and hail model developed by Poolman (1992) and improved upon by Brimelow et al. (2002) and Jewell and Brimelow (2009).

HAILCAST is designed to be embedded within a convective-allowing forecast model. It will produce forecasts of hail size, and if desired, hail density and terminal velocity. Key features include:

• Hailstone growth through liquid water accretion, ice particle collection, condensation, and sublimation
• Explicit calculation of hailstone temperature
• Regimes of wet and dry growth
• Use of multiple initial embryo sizes and insertion temperatures
• Parameterized horizontal motion of the hailstone through the convective updraft
• Variable hail density including rime soaking
• Temperature-dependent ice collection efficiency
• Liquid water shedding
• Enhanced melting during collision with >0°C water

References:

Adams-Selin, R.D. and C.L. Ziegler, 2016: Forecasting hail using a one-dimensional hail growth model within WRF. Mon. Wea. Rev., 144, 4919–4939.

Jewell, R., and J. Brimelow, 2009: Evaluation of Alberta hail growth model using severe hail proximity soundings from the United States.. Wea. Forecasting, 24, 1592–41609.

Brimelow, J. C., G. W. Reuter, and E. R. Poolman, 2002: Modeling maximum hail size in Alberta thunderstorms. Wea. Forecasting, 17, 1048–41062.

Poolman, E. R., 1992: Die voorspelling van haelkorrelgroei in Suid-Afrika (The forecasting of hail growth in South Africa). M.S. thesis, Faculty of Engineering, University of Pretoria, 113 pp.

Download and Instructions:

Code and instructions for using HAILCAST within a convection-allowing model available here.

Code and instructions for using HAILCAST as a 3d hail trajectory model within a steady-state system available here.

Contact Information:

Rebecca Adams-Selin
rselin at aer dot com

All emails will be reviewed. However, help for users is limited, and timely responses are not guaranteed.