FGUS73 KLSX 141813 ESFLSX ILC001-009-013-027-051-149-MOC051-053-071-073-099-111-113-127- 137-151-163-173-183-189-221-291800- PROBABILISTIC HYDROLOGIC OUTLOOK NATIONAL WEATHER SERVICE ST. LOUIS MO 110 PM CST Thu Mar 14 2024 ...Spring Flood and Water Resources Outlook Number 3... ...Near-normal flood chances along the Illinois River... ...Below-normal flood chances along the Mississippi and Missouri rivers... ...Below-normal flood chances along most local tributaries... This outlook uses the term St. Louis Service Area to refer to the Mississippi River from above Canton, Missouri to below Chester, Illinois; the Missouri River above Jefferson City, Missouri to its confluence with the Mississippi River; the Illinois River downstream from Beardstown, Illinois to its confluence with the Mississippi River; and for tributaries of these rivers in central and eastern Missouri and in west central and southwest Illinois. The probabilities within this outlook are not skewed by any ongoing flooding nor by any anticipated excessive rainfall. This outlook is based on current streamflows and soil moisture over the area; upstream snowpack in the Mississippi, Missouri, and Illinois river basins; and forecast rainfall over the next two weeks to three months. More-than-expected rainfall could cause additional flooding over the area, while less-than-expected rainfall could keep rivers from reaching the crests considered likely. The lower Missouri River basin continues to experience widespread persistent drought. This is particularly true across Iowa, southeastern Nebraska, and much of northeastern Kansas. This coupled with low flow along the Missouri and a lack of snow cover continues to render below-normal flood probabilities from Jefferson City to St. Charles. The only two locations where minor flooding is likely this spring through mid-June are at Chamois and at Hermann. These minor flood probabilities are 22 to 27 percent below historical norms. In the Mississippi River basin, the snow water content in the headwaters is non-existent. Streamflow along the Mississippi River has fallen back to well-below-normal levels this month, though it is forecast to rise several feet at St. Louis and at Chester in response to this week's convective rainfall. That said, the lack of snow cover combined with below-normal soil moisture in place from the Twin Cities to south of St. Louis results in a below-normal risk of flooding along the Missouri-Illinois stretch of the Mississippi River. In fact, even minor flooding is unlikely at any forecast point along the Missouri-Illinois border through mid-June. There are near- to below-normal flood chances along most local streams in the St. Louis Service Area over the next 90 days. Over much of eastern and central Missouri, stream flows have fallen below the 25th percentile for mid-March, with several locations below the 10th percentile. Similarly low flows are in place across southern Illinois. For the St. Louis service area, outlooks from the Climate Prediction Center indicate a likelihood of near-normal temperatures and near- to above-normal precipitation for both the next 6-10 day period and the 8-14 day period. Meanwhile, the outlook for the 3 months from April through June indicates a slight likelihood for above-normal temperatures, equal chances of below-, near-, and above-normal precipitation over most of the service area, and a slight favoring of above-normal precipitation over southeastern Missouri and southern Illinois. In Table 1 below, the current (CS) and historical (HS) or normal probabilities of exceeding minor, moderate, and major flood stages are listed for the valid time period. CS values indicate the probability of reaching a flood category based on current conditions. HS values indicate the probability of reaching a flood category based on historical or normal conditions. When the value of CS is more than HS, the probability of exceeding that level is higher than normal. When the value of CS is less than HS, the probability of exceeding that level is lower than normal. ...Table 1--Probabilities for minor...moderate and major flooding... Valid Period: 03/18/2024 - 06/16/2024 : Current and Historical : Chances of Exceeding : Flood Categories : as a Percentage (%) Categorical : Flood Stages (FT) : Minor Moderate Major Location Minor Mod Major : CS HS CS HS CS HS -------- ----- ----- ----- : --- --- --- --- --- --- :Mississippi River Canton 15.0 20.0 25.0 : 19 63 <5 16 <5 <5 LaGrange 17.0 23.0 25.0 : 12 53 <5 10 <5 <5 Quincy 19.0 22.0 26.0 : 14 56 8 28 <5 10 Lock & Dam 21 18.0 21.0 25.0 : 13 55 7 26 <5 10 Hannibal 17.0 22.0 24.0 : 20 61 6 14 <5 10 Saverton 16.0 20.0 24.0 : 24 64 8 39 <5 11 Louisiana 15.0 20.0 25.0 : 37 73 8 33 <5 8 Clarksville 25.0 31.0 33.0 : 37 73 7 28 <5 13 Winfield 26.0 30.0 34.0 : 30 67 8 43 <5 10 Grafton 20.0 24.0 29.0 : 20 67 6 19 <5 6 Mel Price LD 21.0 29.0 34.0 : 37 74 14 21 <5 9 St. Louis 30.0 35.0 40.0 : 28 56 15 34 8 14 Herculaneum 26.0 32.0 37.0 : 36 60 16 36 9 15 Chester 27.0 35.0 40.0 : 46 79 22 41 13 22 :North Fabius River Ewing 11.0 17.0 20.0 : 49 51 14 15 9 10 :Middle Fabius River Ewing 12.0 17.0 20.0 : 48 46 13 14 10 10 :South Fabius River Taylor 10.0 14.0 19.0 : 30 48 12 14 <5 <5 :North River Palmyra 13.0 16.0 22.0 : 20 26 9 10 <5 <5 :Mid Fork Salt River Holliday 17.0 22.0 26.0 : 54 54 <5 <5 <5 <5 :Salt River New London 19.0 25.0 27.0 : <5 <5 <5 <5 <5 <5 :Cuivre River Troy 21.0 25.0 29.0 : 51 53 20 22 7 8 Old Monroe 24.0 27.0 30.0 : 26 60 14 26 <5 14 :Dardenne Creek St. Peters 18.0 20.0 23.0 : 36 36 28 28 8 8 :Meramec River Steelville 12.0 20.0 25.0 : 45 41 <5 <5 <5 <5 Sullivan 11.0 20.0 29.0 : 64 64 12 12 <5 <5 :Bourbeuse River Union 15.0 22.0 26.0 : 52 50 11 11 <5 <5 :Meramec River Pacific 15.0 23.0 27.0 : 37 40 7 7 <5 <5 :Big River Byrnesville 16.0 20.0 28.0 : 42 48 18 20 <5 <5 :Meramec River Eureka 19.0 26.0 31.0 : 36 41 15 17 7 7 Valley Park 18.0 21.0 27.0 : 44 48 30 37 16 25 Fenton 23.0 29.0 32.0 : 39 50 17 24 12 14 Arnold 24.0 35.0 38.0 : 45 78 21 28 12 22 :Kaskaskia River Vandalia 18.0 24.0 26.0 : 74 80 31 36 17 19 Carlyle 16.5 23.0 27.0 : 38 76 <5 <5 <5 <5 New Athens 79.0 82.0 85.0 : 36 41 34 34 25 28 :La Moine River Ripley 22.0 23.0 27.0 : 37 45 33 37 10 11 :Moreau River Jefferson City 17.0 25.0 29.0 : 62 75 41 50 20 28 :Hinkson Creek Columbia 15.0 18.0 20.0 : 64 56 58 31 53 9 :Maries River Westphalia 10.0 15.0 20.0 : 43 44 21 23 <5 <5 :Gasconade River Rich Fountain 20.0 25.0 30.0 : 28 40 18 25 6 10 :Missouri River Jefferson City 23.0 25.0 30.0 : 46 69 29 55 16 25 :Osage River St. Thomas 23.0 30.0 35.0 : 10 17 <5 <5 <5 <5 Mari-Osa Campgrou 19.0 22.0 25.0 : 42 60 22 31 14 22 :Missouri River Chamois 17.0 28.0 31.0 : 57 79 13 17 <5 10 Hermann 21.0 26.0 33.0 : 54 79 26 47 20 21 Washington 20.0 28.0 31.0 : 46 73 20 21 8 19 St. Charles 25.0 30.0 36.0 : 48 75 22 26 6 14 Legend CS = Conditional Simulation (Current Outlook) HS = Historical Simulation FT = Feet In Table 2 below...the 95 through 5 percent columns indicate the probability of exceeding the listed stage levels (FT) for the valid time period. ...Table 2--Exceedance Probabilities... Chance of Exceeding Stages at Specific Locations Valid Period: 03/18/2024 - 06/16/2024 Location 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :Mississippi River Canton 6.2 6.8 8.9 11.7 14.3 16.4 18.9 LaGrange 7.1 7.7 9.8 12.6 15.2 17.3 19.8 Quincy 12.2 12.4 12.9 14.8 17.5 19.9 23.1 Lock & Dam 21 6.6 7.5 10.0 13.0 16.3 18.6 21.8 Hannibal 11.0 11.4 12.6 14.6 16.3 18.9 22.3 Saverton 7.3 8.1 9.9 13.2 15.9 19.0 22.7 Louisiana 12.0 12.0 12.1 13.8 16.3 19.1 21.9 Clarksville 17.8 18.4 20.2 23.5 26.7 29.6 32.3 Winfield 17.7 18.3 20.3 23.7 27.0 29.7 32.2 Grafton 15.2 15.4 15.8 16.8 19.7 21.5 24.5 Mel Price LD 9.6 11.0 13.6 20.0 24.4 31.3 32.7 St. Louis 11.8 14.4 18.2 24.9 31.6 39.0 41.0 Herculaneum 9.9 12.5 16.3 22.8 29.3 36.7 38.7 Chester 14.0 16.1 21.6 26.7 33.2 42.8 43.5 :North Fabius River Ewing 5.8 6.9 8.5 10.9 14.2 19.8 22.3 :Middle Fabius River Ewing 5.0 6.2 8.5 11.1 15.3 20.0 22.2 :South Fabius River Taylor 4.9 5.5 6.7 8.8 11.1 14.9 18.3 :North River Palmyra 5.3 5.5 7.6 8.9 11.6 15.8 18.1 :Mid Fork Salt River Holliday 10.5 11.7 15.5 17.1 18.9 20.7 21.5 :Salt River New London 4.8 6.5 9.1 9.4 10.6 12.6 13.4 :Cuivre River Troy 10.5 11.7 16.1 21.6 24.4 28.4 29.4 Old Monroe 14.2 15.2 17.0 21.0 25.0 27.8 29.0 :Dardenne Creek St. Peters 7.1 8.5 10.4 15.1 20.7 22.6 23.8 :Meramec River Steelville 4.1 5.1 6.8 10.9 13.9 16.1 19.6 Sullivan 6.8 7.5 9.2 13.2 16.6 20.6 25.6 :Bourbeuse River Union 8.0 9.5 11.5 15.1 19.4 22.9 25.6 :Meramec River Pacific 4.2 6.8 9.9 13.9 17.2 22.1 26.0 :Big River Byrnesville 7.2 8.4 11.3 14.8 18.4 22.4 25.2 :Meramec River Eureka 8.6 9.5 13.7 16.3 21.7 28.0 34.9 Valley Park 8.9 9.8 12.3 14.8 24.4 34.4 38.6 Fenton 13.3 15.9 18.1 21.1 26.7 34.1 37.9 Arnold 13.6 15.4 21.3 23.3 31.8 39.0 40.9 :Kaskaskia River Vandalia 10.4 14.3 16.9 21.9 25.2 27.1 28.5 Carlyle 12.2 12.5 13.9 16.2 19.3 21.1 21.3 New Athens 70.0 70.8 72.4 75.8 85.0 89.6 92.3 :La Moine River Ripley 11.3 13.3 16.9 19.6 25.3 27.1 28.2 :Missouri River Jefferson City 10.2 14.0 17.0 21.4 25.1 35.2 35.9 :Osage River St. Thomas 7.4 10.2 11.8 12.9 15.1 23.1 24.4 Mari-Osa Campgrou 8.3 12.5 13.8 17.5 20.7 27.0 29.9 :Missouri River Chamois 8.6 11.7 13.5 18.8 22.9 29.0 30.5 Hermann 12.5 15.2 16.9 21.9 26.6 34.3 35.3 Washington 10.3 12.1 13.7 18.9 22.8 30.1 32.7 St. Charles 17.6 19.1 20.3 24.4 27.6 35.1 36.3 In Table 3 below...the 95 through 5 percent columns indicate the probability of falling below the listed stage levels (FT) for the valid time period. ...Table 3--Nonexceedance Probabilities... Chance of Falling Below Stages at Specific Locations Valid Period: 03/18/2024 - 06/16/2024 Location 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :Mississippi River Canton 4.7 4.5 4.3 3.5 2.9 2.5 2.1 LaGrange 5.6 5.4 5.2 4.4 3.8 3.4 3.0 Quincy 11.8 11.7 11.7 11.2 10.9 10.9 10.9 Lock & Dam 21 5.2 5.0 4.8 4.1 3.4 3.0 2.6 Hannibal 10.3 10.2 10.1 9.9 9.8 9.6 9.5 Saverton 6.0 5.8 5.6 4.9 4.4 4.0 3.9 Louisiana 11.9 11.9 11.9 11.9 11.8 11.8 11.8 Clarksville 16.1 16.0 15.6 14.5 14.0 13.5 13.2 Winfield 15.9 15.8 15.4 14.4 13.9 13.4 13.0 Grafton 15.0 15.0 14.9 14.8 14.7 14.6 14.5 Alton 19.0 18.8 17.6 15.8 14.3 14.3 14.3 Mel Price LD 5.6 5.6 5.2 4.7 4.1 3.0 2.9 Chester 6.2 5.6 5.0 4.5 4.2 2.3 1.5 :North Fabius River Ewing 3.6 3.6 3.4 3.2 3.0 2.9 2.8 :Middle Fabius River Ewing 3.1 3.1 2.9 2.7 2.6 2.5 2.3 :South Fabius River Taylor 1.9 1.7 1.5 1.5 1.3 1.3 1.0 :North River Palmyra 3.7 3.6 3.5 3.4 3.1 2.6 2.6 :Mid Fork Salt River Holliday 4.5 4.4 4.2 4.1 4.0 3.7 3.7 :Salt River New London 4.8 4.7 4.2 3.4 2.1 1.9 1.9 :Cuivre River Troy 5.6 5.5 5.3 5.2 5.1 4.9 4.9 Old Monroe 12.1 11.9 11.3 10.1 9.5 9.4 9.3 :Dardenne Creek St. Peters 1.7 1.6 1.5 1.4 1.3 1.2 1.1 :Meramec River Steelville 2.3 2.3 2.0 1.8 1.7 1.6 1.5 Sullivan 4.2 4.1 3.7 3.5 3.2 3.2 3.0 :Bourbeuse River Union 2.5 2.4 2.3 2.2 2.0 1.9 1.8 :Big River Byrnesville 3.1 2.7 2.5 2.1 1.9 1.7 1.6 :Meramec River Eureka 4.0 3.8 3.5 3.2 3.0 2.9 2.8 Fenton 3.6 3.5 2.6 2.1 1.8 1.2 1.2 Arnold 7.9 7.7 7.4 7.0 6.7 6.5 6.4 :Kaskaskia River Vandalia 6.5 4.8 2.9 2.1 1.8 1.5 1.5 Carlyle 10.8 10.3 5.7 5.5 5.5 5.5 5.5 New Athens 69.3 69.0 68.8 68.6 68.5 68.5 68.5 :La Moine River Ripley 5.9 5.4 5.1 4.8 4.5 4.4 4.3 :Missouri River Jefferson City 1.2 1.2 1.2 1.2 1.2 1.2 1.2 :Osage River St. Thomas 3.6 3.1 2.6 2.5 2.5 2.4 2.0 :Missouri River Hermann 2.2 2.2 2.1 2.1 2.1 2.1 2.1 Washington 0.5 0.4 0.4 0.4 0.4 0.4 0.4 St. Charles 7.2 7.2 7.2 7.2 7.2 7.2 7.1 These long-range probabilistic outlooks contain forecast values that are calculated using multiple season scenarios from 30 or more years of climatological data...including current conditions of the river...soil moisture...snow cover...and 30 to 90 day long-range outlooks of temperature and precipitation. By providing a range of probabilities...the level of risk associated with long-range planning decisions can be determined. These probabilistic forecasts are part of the National Weather Service's advanced hydrologic prediction service. Visit our web site weather.gov/lsx for more weather and water information. The next 90-day outlook will be issued on or about the 28th of March. $$ Fuchs