Heat Burst Index (for extreme Dry Microburst events)
The Heat Burst Index is an empirical index designed to help
forecast the rare "heat burst" event. The heat burst is typically
associated with a decaying thunderstorm, which develops into an extreme Dry
Microburst event that can produce extremely dry air at well over 100 degrees
Fahrenheit with hurricane force winds. There have been
historical reports where heat bursts have carbonized vegetation with brutally
hot and dry winds in just a few minutes
(http://www.accuweather.com/en/weather-blogs/weathermatrix/the-texas-heat-1/4574).
This Heat Burst Index is a composite of key thermodynamic properties associated
with the "Inverted-V"
profile, which is the signature sounding shape often associated with dry microbursts
and heat bursts. This index goes beyond the more limited DMPI (Dry
Microburst Potential Index) parameter, and includes lapse-rates, moisture
profiles, cloud layers, wind shear, energy potential, inversions, and other
physical properties associated with the Inverted-V sounding structure.
This index can out-perform typical CAPE-based storm indices at detecting burst events, because these events often contain little or no CAPE, and they often occur at night.
Suggested index probability thresholds:
Index Probability
-------------------
> 500 Weak
> 750 Moderate
>1000 Strong
See other RAOB parameter display options.
Return to www.raob.com