Flood waters from North Dakota’s Souris River are pouring over the levees protecting Minot, North Dakota today, and flood heights are expected to rise to the highest levels in recorded history tonight. The Lake Darling flood control reservoir located about 15 miles upstream from Minot is full to overflowing, and record releases of water are occurring to prevent the lake’s dam from over-topping. By this weekend, the Army Corps of Engineers will open the dam’s flood gates to a maximum flow rate of 20,000 cubic feet per second, which is roughly double the flow rate that the levees in Minot can handle. Water began flowing over the levees yesterday, forcing the mandatory evacuation of 12,000 residents. By Sunday, water levels on the Souris River are expected to peak at four feet above the previous all-time flood height, set in 1881. Torrential rainfall in Canada on Sunday and Monday, combined with very heavy rainfall and snow melt over North Dakota over the past month, are responsible for the record flood. The Souris River Basin near the Rafferty Dam in Saskatchewan received four to seven inches of rain Sunday into Monday. Flood heights along the Souris River near the Canadian border upstream from Minot are already two feet above the previous all-time highest mark, and that pulse of water is now arriving in Minot. The unprecedented flood is expected to keep much of Minot underwater for at least two weeks. Fortunately, no new heavy rains are expected over the next five days, though up to 1/2″ of rain could fall over portions of the Souris River watershed.

Figure 1. Still frame from a Youtube video of the Souris River in Minot, North Dakota flowing over the levees in that town. The video was shot on Wednesday June 22, 2011, from a North Dakota National Guard helicopter.

Figure 2. Observed (blue line) and forecast (green line) stage of the Souris River in Minot, North Dakota. The river is currently at its 3rd highest level on record, and is expected to rise above the record flood stage of 1558′ tonight. The record was set back in 1881. Image credit: NOAA AHPS.

Record rains in China kill 175, do $5 billion in damage
Torrential rains triggered severe flooding in eastern China this week, with the death toll for June floods now standing at 175, with 86 people missing. Ironically, the same region experienced severe drought at the beginning of June. The estimated $5 billion in damage from the floods would make 2011 the third most expensive year for floods in China in the past decade. This year is the second consecutive year floods have caused exceptional damage in China. Last year, Western China saw summer precipitation more than 200% above average, and torrential monsoon rains triggered catastrophic landslides that killed 2137 people and did $759 million in damage. Monsoon floods in China killed an additional 1911 people, affected 134 million, and did $18 billion in damage in 2010, according to the WHO Collaborating Centre for Research on the Epidemiology of Disasters (CRED). This was the 2nd most expensive flooding disaster in Chinese history, behind the $30 billion price tag of the 1998 floods that killed 3656 people. China had floods in 1915, 1931, and 1959 that killed 3 million, 3.7 million, and 2 million people, respectively, but no damage estimates are available for these floods. During the period 2000 – 2009, China averaged $3.7 billion in damage and 674 deaths per year due to floods and landslides, according to the WHO Collaborating Centre for Research on the Epidemiology of Disasters. This does not include the toll from typhoons. Speaking of typhoons, Tropical Storm Meari, currently located a few hundred miles east of the Philippines’ Luzon Island, is expected to track north-northwestwards towards China today and Friday. By Saturday, Meari is expected to be a Category 1 typhoon, and will spread heavy rains over eastern China, worsening the flooding situation there–though the heaviest rains will likely remain offshore.

Figure 3. Rainfall amounts in excess of 18 inches (450 mm) fell in Eastern China southeast of Shanghai in a 1-week period, June 13 -19, 2011. A China Daily report from June 18 described the rains in parts of Zhejiang Province as unprecedented. High waters broke 100-meter (300-foot) holes in levees, inundating nearby villages. Some homes were buried in 3 meters (10 feet) of water. This image is based on data from the Multisatellite Precipitation Analysis produced at Goddard Space Flight Center, which estimates rainfall by combining measurements from many satellites and calibrating them using rainfall measurements from the Tropical Rainfall Measuring Mission (TRMM) satellite. Image credit: NASA.

Figure 4. Visitors watch as water gushes out from the Xiaolangdi Reservoir on the Yellow River in Central China’s Henan province, June 22, 2011. Image credit: Xinhua.

The Atlantic is quiet
The Atlantic is quiet, but several models, including the NOGAPS and GFS, are predicting that a tropical disturbance capable of becoming a tropical depression could form in the southern Gulf of Mexico in the Bay of Campeche Tuesday or Wednesday. There will be a strong ridge of high pressure over the Gulf next week, which would tend to keep any storm that might form far to the south, with impacts limited to Mexico and perhaps South Texas.

Jeff Masters