Storm Prediction Center forecasting issues related to the 3 May 1999 tornado outbreak

Forecasters at the Storm Prediction Center (SPC) were faced with amny challenges during the 3 May 1999 tornado outbreak. Operational numerical forecast models valid during the outbreak gave inaccurate, inconsistent, and/or ambiguous guidance to forecasters, most notably with varying convective preciptation forecasts and underforecast wind speeds in the middle and upper troposphere, which led forecasters (in the early onvective outlooks) to expect a substantially reduced tornado threat as compared with what was observed.