During the IHOP (International H2O Project) the NOAA Forecast Systems Laboratory ran several configurations of the RUC and MM5 models over various domains, in part to provide forecast and nowcast guidance for project operations. IHOP was conducted from 13 May to 25 June 2002, over the Southern Great Plains. The main goal of IHOP was better characterization of the four-dimensional (4-D) distribution of water vapor and its application to improving the understanding and prediction of convection.

The FSL experimental models run during IHOP included the RUC model at 20 km and 10 km horizontal grid resolution, and the MM5 model initialized with LAPS at 12 km and 4 km horizontal grid resolution. Forecasters were able to examine these models in real-time during IHOP using FX-Net, a limited functionality workstation based on AWIPS. In addition, forecasters also had access to the NCEP operational model suite, providing a rare real-time opportunity to study the capabilities of models at different resolutions in predicting what is climatologically in springtime a very wide variety of convective activity.

We give a detailed subjective evaluation of model performance, with emphasis on prediction of low-level boundaries, convective initiation and organization. This is based on a questionaire the forecasters completed in the field, plus notes made in the JOSS log during the experiment, as well as limited post-experiment analysis of the model forecasts. In addition we will be evaluating reruns for interesting cases of MM5 and WRF, both initialized from LAPS, to assess the impact of improved diabatic initialization procedures. The opportunity also exists, with the considerable model diversity available, to study the added value, if any, of this de facto ensemble of forecasts.