In Oct 1997, Air Force Weather Agency (AFWA) began running the Penn State University/National Center for Atmospheric Research (PSU/NCAR) Mesoscale Model Version 5 (MM5) over the CONtinental United States (CONUS) at a resolution of 36 km. Since the Spring of 1998, AFWA has been running three inner nests within the CONUS window. Output from these windows are used by the CONUS Severe Weather Forecast Operations Branch, and disseminated to operational customers worldwide via the World Wide Web. These inner nests have a resolution of 12 km and cover an 1130 km by 1370 km region.
AFWA has been experimenting with a 4 km "inner inner" nest for weather support during severe weather season and for support to space shuttle operations. With this higher resolution, the forecasters supporting various missions around the world could be able to identify those minute mesoscale changes in the form of wind, moisture, and stability patterns which could help provide better lead time for tornadoes, large hail, high wind events, and those convective elements which could force the delay or postponement of shuttle launches. Severe storm indices have been developed using MM5 (including Lifted Index, Moisture Convergence, and CAPE), but have only been used operationally at resolutions of 12 and 36 km. The two cases to be presented are from early April 1998 (severe tornadic storms over the lower Mississippi River valley) and from mid June 1998 (severe tornadic storms over eastern Nebraska). At 4 km resolution, the MM5 proved to be very valuable.
The 8th Conference on Aviation, Range, and Aerospace Meteorology