*Where Did All of the Severe Weather Go?*

Storm Chase 2009

Since we have been on the storm chase there have only been 11 tornadoes reported in the Great Plains.  Such a small number is absolutely unheard of for the severe weather month of May.  We were truly blessed to have seen the tornado in Ponca City, OK.  This rare severe weather event is due to a REX block.  This particular block usually occurs in the spring near the west coast, but this time it occurred on the east coast.  It has two adjacent highs and low pressure systems.  The jet stream is located extremely north (closed to Canada) and the subtropical jet is located extremely south (below Florida), causing the airflow to have a backward ‘S’ flow pattern. The low pressure system moving east toward Florida is set up underneath a high pressure system in the eastern US, causing a  backward ‘S’ flow pattern.  That flow pattern blocks systems from flowing through the Great Plains, allowing clear skies.  This is extremely rare because it is early for the tropical waters to be warm enough to be disturbed.