Abstract

In the past, vertically integrated liquid water (VILW) and liquid water content (LWC) were used as predictors for hailstone diameter. However, forecasts using these values as primary predictors display little or no skill. Further research on the growth of hailstones produced the HAILCAST model, which was later integrated into the Weather Research and Forecasting (WRF) model to produce the WRF-HAILCAST model. This model included updated hail formation physics including differing hail densities for wet versus dry growth and mass growth due to water vapor deposition and condensation. Despite these updates, the WRF-HAILCAST model falls short in hailstone diameter prediction. Due to its connection with the severity of storms and the amount of precipitation produced, total precipitable water (TPW) may be a viable candidate for further improvement of these forecasts. Hailstone diameter data from the Severe Hazards and Analysis Verification Experiment (SHAVE) from 2014 is compared with the TPW data from the National Centers for Environmental Prediction and the National Center for Atmospheric Research (NCEP/NCAR) 40-year reanalysis archive to determine a correlation between TPW and hailstone diameter. This study found that TPW does not hold a strong positive correlation with hailstone diameter. However, a range of TPW does correlate with ranges of hailstone diameters and was shown to be statistically significant. Since TPW can be measured before a hailstorm occurs these relationships will lead to greater insight for predicting hailstone diameter.

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