Forecasters discuss model predictions of extreme precipitation at the Hazardous Weather Testbed during the 'Spring Experiment'. (Photo courtesy Faye Barthold)

Results from HMT-HPC Hazardous Weather Testbed Annual Spring Experiment

Over a five-week period from mid May through mid June 2010, the NOAA Hydrometeorology Testbed at the Hydrometeorological Prediction Center (HMT-HPC) led a quantitative precipitation forecast (QPF) component of the Hazardous Weather Testbed's annual Spring Experiment.

The QPF component explored the use of high resolution (1-4 km) convection-allowing deterministic and ensemble model guidance for forecasting precipitation associated with warm-season convection. During the experiment, participants issued daily experimental probabilistic QPFs indicating the potential for exceeding both 0.5" and 1.0" of precipitation during two near-term six-hour periods. Subsequently participants then subjectively evaluated the quality of their forecasts and the quality of the available model guidance relative to the observed precipitation.

The high-resolution models demonstrated skill in warm-season QPF, which portends well for improved QPFs. In particular, the subjective evaluations showed that 65% of the forecasts from the Storm Scale Ensemble Forecast system (SSEF), a 4-km 26-member ensemble provided by the University of Oklahoma's Center for Analysis and Prediction of Storms (CAPS), and 57% of the forecasts from the WRF-NSSL4, a 4-km deterministic model provided by the National Severe Storms Laboratory (NSSL), provided better forecast guidance than their operational counterparts, namely the Short Range Ensemble Forecast System (SREF) and the North American Mesoscale Model (NAM), respectively.

Participating in this experiment enabled HPC forecasters to gain valuable experience using high-resolution model guidance and to begin determining how best to incorporate this guidance into their forecast process. Work is already underway to expand the QPF component of the 2011 Spring experiment. This work complements similar efforts in HMT-West.