Short-term Prediction Research
and Transition Center

Modeling & Data Assimilation Projects

WRF forecasts with the Miami WFO

Over the last few years, research at the SPoRT Center has suggested that the use of high-resolution MODIS SST data in regional numerical weather prediction models can have a significant impact on short-term weather forecasts in coastal regions. In fact, the recent paper by LaCasse et al. (2007) highlights lower atmospheric differences over the ocean from a May 2004 case study period. To help quantify the value of this impact on the WFOs, the SPoRT Center and the Miami National Weather Service Forecast Office (MIA) have begun a project to investigate the impact of using high-resolution MODIS sea surface temperature (SST) fields within the Weather Research and Forecasting (WRF) prediction system. The scientific hypothesis to be tested is: Accurate specification of the lower-boundary forcing within WRF will result in improved land/sea fluxes and hence, more accurate evolution of coastal mesoscale circulations and the sensible weather elements associated with them.

MIA is currently running the WRF system, with the Nonhydrostatic Mesoscale Model dynamic core, in real-time in support of daily forecast operations. Twenty-seven hour forecasts are initialized at 03, 09, 15, and 21 UTC using analyses created by the Local Analysis and Prediction System (LAPS) with the diabatic "hot-start" option. The sea surface temperatures are initialized with the NCEP Real-Time Global (RTG) analyses at 1/12° resolution.

SPoRT will conduct parallel WRF runs that are identical to those executed at MIA in every way except for the use of MODIS SST composites in place of the RTG product. A comparison of the SPoRT and Miami forecasts is planned for Spring 2007. This will include quantitative verification of near-surface temperature and wind forecasts using surface observations. In addition, particular days of interest will be subjectively analyzed to determine the impact on clouds and precipitation.

Surface skin temperature (K) mapped to the 4-km WRF domain including the RTG SSTs (left) or the MODIS SST composite (right) valid at 9 UTC 16 February 2007.