It was around 8:30 p.m. that a sudden deepening of water on the streets NOT near creeks and irrigation ditches began to develop.     This "surge" can be traced eastward at just under one mph through eyewitness interviews and logs of E-911 calls.
          This figure shows a few locations where the sudden surge was observed.   Times of the various observations are; 'a' (~8:30 p.m.);   'b' (~9:00 p.m.);   'c' (~9:30 p.m.);   'd' (~10:00 p.m.);   'e' (10:20 - 10:25 p.m.);   'f' (10:52 p.m., exactly),   and 'g' (12:15 a.m.).     Also, you can click here for a map of a few discharge estimates made following the flood.