Accuracy of Rapid Update Cycle low-level jet forecasts

A study verifying low-level jet forecasts produced by the Rapid Update Cycle (RUC) model was performed using profiler and wind-turbine tower data. The National Oceanic and Atmospheric Administration’s (NOAA’s) wind profiler data (< 1500 m AGL) were used to evaluate the accuracy of speed, vector, and low-level shear forecasts for 1-,3-,and 6-h RUC forecasts initialized every three hours (0000, 0300, …2100 UTC) from the summer of 2003. In addition, wind tower data obtained for the same period, were obtained from the National Renewable Energy Laboratory (NREL) for six locations in Texas, Kansas, and Oklahoma. These data provide boundary layer observations (50-, 80-, and 110 m) that were used to verify low-level jet forecasts at these locations for the same period.

Preliminary results indicate that the RUC slightly under forecasts the intensity of the low-level jet at the profiler and wind-tower verification sights. As expected, the errors increase with altitude, but shear errors were relatively small. This result suggest that short-term RUC forecasts can provide severe weather forecasters important information about shear profiles crucial to the prediction of severe storms.