A number of National Weather Service offices run their own local versions of high resolution numerical weather models to help provide additional information to their forecasters. SPoRT’s partners in the Mobile, Alabama NWS office are currently running the Weather Research and Forecasting (WRF) version three model. In this example, Mobile’s local WRF model combined with high resolution sea surface temperatures derived by MODIS, successfully “spun-up” a closed low in the last model run before Tropical Storm Claudette made landfall on August 17th.
In other runs without the MODIS data, the WRF model did not resolve the low due to the small scale of the tropical storm. To be fair, this run likely contained horizontal accelerations that indicated strengthening. However, the North American Model produced a broad surface low that was far west of the official landfall in Okaloosa County, Florida. Lastly, the Rapid Update Cycle model put a broad surface low into Mobile Bay.
In this example, the WRF run with the MODIS sea surface temperatures developed a closed surface low that made landfall in the correct location. The images below show the progression of the model output leading up to landfall. The addition of the MODIS data, combined with the WRF’s ability to “spin-up” horizontal accelerations, make this a great example of how a local model can help forecasters modify a forecast in these short-term situations.
To keep track of these modeling efforts in Mobile, check out the great real-time modeling page put together by their ITO, Ray Ball. (http://www.srh.noaa.gov/mob/wrf.php)