FGUS63 KKRF 131651 ESGKRF _MKCESGKRF SPRING FLOOD OUTLOOK NATIONAL WEATHER SERVICE MISSOURI BASIN RIVER FORECAST CENTER PLEASANT HILL, MO MARCH 13, 2024 NARRATIVE PART 1 OF 1 ATTN WFO'S SERVED BY MBRFC. This Spring Flood Outlook is not for public release until Thursday, 14 March 2024. This Spring Outlook is for the Missouri River drainage which includes rivers in Montana, Wyoming, Colorado, North and South Dakota, Nebraska, Kansas, Iowa, Minnesota, and Missouri. SPRING FLOOD OUTLOOK Flood risk this Spring within the Missouri River basin continues to vary from near-normal to below-normal. No areas have an above-normal risk for flooding this Spring. To provide context, a normal risk indicates that a location that typically experiences Spring time flooding is likely to see flooding again this year. However, a normal risk for flooding does not necessarily mean that a location is expected to flood. For those locations which do not typically experience flooding, a normal risk simply indicates that flooding is again not expected this year. By the same token, a reduced risk of flooding does not necessarily mean that flooding is not expected. On the other hand, an increased risk does not necessarily indicate flooding is likely. While soil moisture conditions have improved over the past year, the US Drought Monitor valid 05 March 2024 still shows 65% of the Missouri River basin as being abnormally dry. This drier than normal soil moisture condition plays a key role in the reduced flood risk found in many areas of the basin. Mountain snowpack is well below average in the Milk, upper Missouri, and Yellowstone River basins. The headwaters of the Platte River system are faring much better, with a near-average snowpack. Flooding in the mountainous areas due to snowmelt alone is not likely this year. Water supply forecasts issued in early March by the National Weather Service project lower than average April-September runoff volumes for most of the mountainous west. More information regarding current Water Supply Forecasts can be accessed at weather.gov/mbrfc/water There is almost a complete absence of plains snow in the Missouri River basin at this time. While the absence of plains snow figures into the reduction of Spring flood risk, it has allowed a decent frost depth to develop in some areas. Frozen ground could play a significant role in enhancing runoff across portions of North Dakota and Montana. With the warmer-than-normal temperatures experienced across the basin over the past couple of months, river ice along many of the rivers in the northern plains is either rotting in place, or has moved out altogether. Although the risk for future ice jam break-up flooding is now considered low, wherever river ice remains, so does the risk for ice jam flooding. Please note, the probabilistic quantifications that form the basis for this Spring Flood Outlook do not take into account the presence of river ice. Springtime flooding in the lower one-third of the basin, including eastern Kansas and the state of Missouri, is driven by the thunderstorm activity typically seen in this area this time of year. Late last week, one tributary located in southern Missouri experienced minor flooding due to receiving about an inch of rain. And so it comes as no surprise that the NWS is projecting continued, on-again, off-again, episodic flooding in the lower basin as we close out the Spring and enter into early Summer. The following state by state flood potential discussions are based on long-range probabilistic river outlooks developed this week. Again, it must be stressed, these outlooks do not take into account the presence of river ice. In Kansas, Stranger Creek is expected to have moderate level flooding, while the Little Osage, Big Blue, and Marias des Cygnes Rivers are projected to have minor flooding. In the state of Missouri, the Grand, Crooked, and Blackwater Rivers are outlooked to experience moderate flooding, as do Hinkson and Big Creeks. The Chariton, Tarkio, Platte, Little Blue, Lamine, Moreau, Big Piney, Little Osage, Marmaton, and Sac Rivers are projected to see minor flooding, as does Wakenda, Moniteau and Petite Saline Creeks. The Missouri River downstream of Kansas City to the mouth is also likely to experience minor flooding between now and mid-June. Looking just beyond the 90-day typical outlook window, minor flooding is possible along the Nebraska City through Atchison reach of the lower Missouri River. These projections of river stages are based on current observed states of streamflow, soil moisture, and snowpack, coupled with future precipitation and temperature patterns and anticipated operational hydrologic changes such as reservoir releases and canal diversions. "Outlooks" are provided for long-range (weeks to months) projections based on climatological patterns of precipitation and temperature. "Forecasts" are provided for short-term (days) projections based on forecast patterns of precipitation and temperature. The uncertainty of these products varies from season to season and location to location. The uncertainty of forecasts tend be less than the uncertainty of outlooks due to their shorter lead time. Users of these products are encouraged to contact their nearest National Weather Service Forecast Office for continued updates of meteorological conditions which can have significant impacts on flood preparedness planning and flood fighting activities. For additional quantitative information please refer to AHPS products for probabilistic outlooks of potential flooding. Refer to short-term flood forecasts and products, if any are currently issued, for information about ongoing or near-term anticipated flooding. This is the last scheduled Spring Outlook of the 2024 season. Should significant changes occur subsequent to this Outlook, additional Outlooks can be released to update expected conditions. Additional river information, including the monthly Water Supply Outlook, can be accessed at the following URL: http://weather.gov/mbrfc Current Snow Conditions The conditions listed below are based on observations and model data as of Wednesday morning, March 13th. Montana, Wyoming, and Colorado Plains Snow depths are generally less than 2 inches with water equivalents less than 0.5 inches across the plains of Montana, Wyoming, and Colorado. Mountainous West Snowpack conditions in the mountainous areas of the basin (as of 12z on March 13th) are generally below normal. In Montana, the Jefferson, Musselshell, Missouri headwaters, Sun, Teton, and Marais River basins are reporting a below normal snowpack (60-80%). The St. Mary and Milk basins are reporting a below normal snowpack (65-75%). In Wyoming, the Tongue, Bighorn, Powder, Wind, and Yellowstone River basins are reporting a below normal snowpack (60-90%). The higher elevations of the North Platte River basin are reporting a below to near normal snowpack (80-100%). In Colorado, the higher elevations of the South Platte River basin are reporting a near normal snowpack (90-100%). An incoming major winter storm could dump 1 to 3 feet of snow over the high elevations of Colorado and Wyoming beginning tonight. North Dakota No snow is being reported across the state of North Dakota. South Dakota The Black Hills in South Dakota have 10-16 inches of snow depth with water equivalents in the 1-3 inch range. Less than one inch of snow depth is being reported across the remainder of the state. Iowa, Nebraska, Missouri, and Kansas No snow is being reported across Iowa, Nebraska, Missouri, and Kansas. Current Soil Moisture Conditions The US Drought Monitor indicates that portions of the Missouri River basin are experiencing below normal soil moisture conditions. Moderate to severe drought is indicated across portions of Montana, northern Wyoming, northern Kansas, southeastern Nebraska, and western Iowa. Abnormally dry to moderate drought is indicated across southern Wyoming, North Dakota, South Dakota, and Missouri. Isolated frost depth reports suggest that soils across Montana, Wyoming, northern South Dakota, and North Dakota have frost penetration ranging from 0.5-3 feet. Frost depths of less than 0.5 feet are being reported across southern South Dakota, Colorado, Kansas, Nebraska, Iowa, and Missouri. Current River Conditions Generally, river levels across the basin are currently running below normal, or estimated to be so if the rivers are frozen. The exception is across southwestern Missouri where rivers are flowing near to slightly above normal due to recent rain. A summary of river flow conditions at selected river stations for March 13th follows: Long Term Current Mean (CFS) (CFS) James River - Huron, SD 411 548 Big Sioux River - Akron, IA 2250 440 Platte River - Louisville, NE 10000 6280 Kansas River - Desoto, KS 3460 1140 Gasconade River - Jerome, MO 2750 2900 Missouri River - Omaha, NE 22400 16100 Missouri River - Rulo, NE 37500 21900 Missouri River - St. Joseph, MO 40000 24300 Missouri River - Waverly, MO 46500 26100 Missouri River - Hermann, MO 72700 39700 END MBRFC $$