Texas/Oklahoma flooding, record rains, Lake Texoma flooding

The jet stream patterns that have set up the current
wet situation in Texas. From Weather.com here
on May 24.

Over 350 homes in Hays County, Texas, are gone, and more than 1000 are damaged according to reports coming out this Memorial Day weekend. At least one person in Texas and two in Oklahoma have died as a result of the storms. The Blanco River surged up 28' in 2 hours as the flood surged to 40', three times the flood level.  And as of this (Sunday) evening, more rains are expected, perhaps 3-5" more.
 
Lake Texoma is the 12th largest US Army Corps of Engineers lake, behind the Denison Dam on the Red River.  It spans both Bryan County, Oklahoma, and Grayson County, Texas at the confluence of the Red and Washita Rivers. The dam site is 5 miles northwest of Denison, Texas. It is a popular lake, attracting about 6 million visitors per year. Water is pouring over the

Lake Texoma Spillway the morning of Sunday,
May 24. From TKKToday here. This is an excellent
site to see current and forecasted conditions as well
as helicopter footage of the flooding.

spillway of the dam for only the fourth time in its history as the inflow to the Lake is 300,000 cubic feet per second (for reference, this is about ten times the maximum discharge of Glen Canyon Dam, and three times the discharge during the 1983 crisis at Glen Canyon Dam). The Denison Dam here was built during World War II, finished in 1944, in order to control flooding along the Red River. spillway previously in 1957, 1990, and 2007. Water pouring over the spillway goes back into the Red River and is not considered a danger to those living in Denison.

U.S. Severe weather map as of 12:26 a.m. GMT (7:26 p.m.
CDT) on May 25 from www.wunderground.com here

As explained on Weather.com with the graphic at the top of this post, in April, the conditions that were causing the drought this past winter in California shifted. The subtropical jet has a trough per the southwest, allowing cyclonic storms to breed over the rockies. These, in turn, enhanced the flow of warm moist air up from the Gulf of Mexico for the past six weeks.

As the severe weather map shows, much of the central U.S. is experiencing severe weather in the form of flood warnings and watches, tornado warnings (red), and high wind advisories (blue and pale green near Chicago).