Leading up to this event, the WFO RAH forecasters used model thicknesses with the TREND technique’s
universal precipitation type nomogram to forecast the predominant p-types and changeovers across the CWA.
The models’ thicknesses proved to be quite accurate and exhibited good run-to-run consistency, which raised
the forecasters’ levels of confidence in the p-type forecasts.
Below is an animation showing the actual thickness values from the GSO soundings taken at 18Z on
December 4, 2002, and 00Z, 06Z, and 12Z on December 5, 2002, plotted on the TREND technique’s universal
p-type nomogram. As the nomogram predicted, precipitation at GSO began as measurable snow and sleet,
followed by a changeover to measurable sleet with freezing rain, and finally to an all-freezing rain event.
RAH P-type Nomogram from 00Z Thursday December 5, 2002.
Click the image to enlarge.