4. Forecast Applications

Convection » Microbursts: Wet vs. Dry Forecasting Microburst Wind Gusts

Several indices have been developed to predict convective wind gusts. In the Convective Wind Gusts section, we demonstrated two methods from the U.S. Air Force. Here, we introduce WINDEX (McCann 1994), which was developed as a direct result of microburst research.

WINDEX (WI) is computed as follows:

WINDEX equation to predict convective wind gusts

where:
WI = maximum wind gust (knots)
HM = height of the melting level (km)
RQ = QL/12 but the value for RQ may not exceed 1
QL = mean mixing ratio in lowest 1 kilometer (g/km)
QM = mixing ratio at melting level (g/km)
gamma = Lapse rate from melting level to surface (°C/km)