Far Upstream Precursors to Severe and Extreme Weather over the Midwestern United States
These two MCSs serve as motivation for a climatology of EML days and their relationship to severe weather over the Midwestern United States. The climatology illustrates that severe weather reports near Minneapolis, MN during the summer are twice as numerous on EML days as compared to normal. The increase in severe weather reports are primarily driven by more large hail and severe wind, which account for 95% of all severe weather reports on EML days. A time-lagged composite analysis indicates that RWT amplification over the central North Pacific and RWT dispersion across the eastern North Pacific and North American, as occurred prior to the 30 June–1 July period, is a common upstream precursor to EML days over the Midwestern United States. These results suggest that investigations of far upstream precursors to RWT amplification and dispersion over the North Pacific may be particularly useful in better understanding warm-season severe weather outbreaks over North America.