This Partners project is a follow-on effort from an ongoing Cooperative project between SUNY Albany and the NWS Storm Prediction Center on upper-level closed lows that move across northern Mexico from the Gulf of Mexico or the eastern North Pacific during the warm season. In that study, researchers have found that many of these events are partially or completely missed by the operational GFS forecasts. At issue is to what extent the failure of the GFS to simulate many of these severe weather-producing upper-level closed lows is a manifestation of the recent degradation of the Mexican radiosonde network.