Development and validation of GFS downscaled numerical guidance

The NAM "smartinit" code has been adapted to work for GFS so that EMC can provide downscaled GFS numerical guidance for up to eight days. The first implementation is scheduled to take place in September 2010 and will only cover Guam domain. In addition to providing Guam forecasters sensible weather forecasts at 2.5 km NDFD resolution, this implementation will also produce the background fields needed for the Guam Real-Time Mesoscale Analysis. The second implementation is planned for next year and will cover NDFD 2.5 km CONUS and Hawaii grids.

The purpose of this paper is to 1) describe the methodology that is used to downscale GFS surface fields, and to 2) show examples of downscaled GFS forecasts as compared to the original GFS forecasts. Results of objective verifications will also be shown to compare the forecast errors of downscaled GFS surface fields with those of other models.