####018011124#### FGUS73 KBIS 281840 ESFBIS NDC009-013-023-049-069-075-079-101-301845- Probabilistic Hydrologic Outlook National Weather Service Bismarck ND 140 PM CDT Thu Mar 28 2024 This Flood and Water Resources Outlook is for the Souris River basin of North Dakota, covering the period of 1 April through 30 June, 2024. This is a routine monthly issuance of flood probabilities for NWS forecast locations. These probabilities are issued on, or around, the fourth Thursday of every month. The following message has four sections. The first provides some text on the highlights of this outlook and conditions affecting the local hydrology. The second section gives the current and normal/historical risks of flooding as determined by the Ensemble Streamflow Forecast model of the National Weather Service. The third section gives the current probabilities for reaching flood stage at the listed forecast locations. And finally, the fourth section covers the risk of the river sites falling below the listed stages. ...Flood Outlook Highlights... The snowpack across the Souris River basin has been in the process of melting its snowpack on and off again over the past several weeks. In general though, the North Dakota portion of the basin is largely snow free with the exception of modest snow coverage in the Turtle Mountain area, and again in the western part of the basin along the Missouri Coteau and part of the Long Creek watershed. In general though, there is not enough snow to really enhance the risk of widespread flooding. Accordingly, the vast majority of the risk of flooding found in the below tables is proportional to the risk of heavy spring rains and the region's entry into its severe thunderstorm season. Overall though, widespread flooding at this point does not appear to be a significant concern without remarkably large amounts of spring rain. ...Snowpack Conditions... Snow continues to come and go with no significant accumulation of water on top of the ground. Where snow does exist in the Turtle Mountain, Missouri Coteau, and Long Creek areas, snow-water equivalent in the snowpack likely ranges from a trace up to maybe one-half of an inch of water. ...Soil Conditions... Soil moisture values across the Souris River Basin in North Dakota are now considered to be near normal across the region with the exception of a somewhat below normal portion north and east of Minot. Frost depth remains highly variable this year and is now even more complicated as recent warm weather had started thawing the ground surface before cold weather once again moved into the region. This leaves at least a part of the area with a frozen ground surface on top of maybe a few inches of thawed soil before it once again cools to below freezing at depth. What this suggests it that although overall frost depth may be greater than 30 inches in some areas, once warm weather again enters this part of North Dakota, the soils may quickly thaw and once again become permeable to infiltration of rain and meltwater. ...Current Drought Conditions... The U.S. Drought Monitor reflects D0 (Abnormally Dry) to D1 (Moderate Drought) across most of the Souris River Basin in North Dakota. Only a portion of western Ward and eastern Mountrail counties are not under a current drought designation. Given the time of year, no significant impacts are noted with the current drought designations. However, concerns with increased drought designations going into spring are warranted, especially since climate outlooks and near-term forecasts do not tend to favor a change in existing trends anytime soon. ...Reservoirs and Natural Wetlands... Lake Darling above Minot along with the Canadian reservoirs behind Grant Devine and Rafferty Dams have captured what they could thus far in trying to reach their full supply level before the end of spring. In general though, they all still retain significant capacity to temper runoff from any currently unforeseen heavy spring rains. ...Weather Outlook... The Climate Prediction Center 6-10 day outlook favors near normal temperature and precipitation. This evolves into a near normal temperature with above normal precipitation for the 8-14 day outlooks. Looking out even farther, the weeks 3-4, one-month, and three month outlooks for April, May and June generally favor above normal temperatures with equal chances for above normal, near normal, or below normal precipitation. ...Ice Conditions... Ice is quickly waning across most of North Dakota with most rivers now being at least mostly ice free after those streams experienced runoff in late winter. Wetlands, ponds, lakes, and larger reservoirs are still largely covered in ice of varying thickness and quality. In Table 1 below, the current (CS) and historical (HS) or normal probabilities of exceeding minor...moderate...and major flood stage 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 greater 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: 04/01/2024 - 06/30/2024 : 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 -------- ----- ----- ----- : --- --- --- --- --- --- :Des Lacs Foxholm 1651.0 1653.0 1654.0 : <5 <5 <5 <5 <5 <5 :Souris Sherwood 1623.0 1625.0 1630.0 : <5 12 <5 5 <5 <5 Foxholm 1573.0 1576.0 1578.0 : 10 35 <5 16 <5 <5 Minot 1562.0 1565.0 1570.0 : 6 16 <5 6 <5 <5 Minot 1551.0 1553.0 1557.0 : <5 <5 <5 <5 <5 <5 Logan 1536.0 1538.0 1540.0 : 7 19 <5 <5 <5 <5 Sawyer 1524.0 1526.0 1528.0 : <5 7 <5 <5 <5 <5 Velva 1507.0 1512.0 1517.0 : 5 17 <5 <5 <5 <5 :Wintering Karlsruhe 1509.0 1511.0 1512.0 : 11 16 <5 <5 <5 <5 :Souris Towner 1454.0 1456.0 1458.0 : 39 61 13 26 <5 <5 Bantry 1440.0 1441.0 1443.0 : 39 62 23 41 <5 8 :Willow Creek Willow City 1442.0 1446.0 1448.0 : 27 48 6 20 <5 <5 :Souris Westhope 1414.0 1418.0 1420.0 : 19 52 <5 22 <5 17 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: 04/01/2024 - 06/30/2024 Location 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :Des Lacs Foxholm 1639.3 1639.4 1640.7 1641.8 1643.3 1644.6 1646.2 :Souris Sherwood 1608.9 1609.2 1610.1 1611.9 1614.8 1618.8 1620.3 Foxholm 1571.0 1571.0 1571.0 1571.0 1571.0 1573.1 1576.0 Minot 1554.1 1554.1 1554.1 1554.3 1555.2 1556.6 1562.8 Minot 1542.8 1542.8 1542.9 1543.0 1543.5 1544.1 1547.1 Logan 1526.6 1526.6 1526.7 1527.1 1528.6 1533.1 1537.1 Sawyer 1512.1 1512.1 1512.2 1512.8 1514.5 1521.1 1523.0 Velva 1496.1 1496.1 1496.2 1496.7 1499.0 1505.8 1507.5 :Wintering Karlsruhe 1503.7 1503.7 1504.3 1506.0 1507.8 1509.0 1509.3 :Souris Towner 1452.3 1452.3 1452.6 1453.4 1454.9 1456.1 1456.7 Bantry 1437.8 1437.9 1438.2 1439.3 1440.8 1441.8 1442.3 :Willow Creek Willow City 1437.2 1437.2 1437.2 1438.2 1442.7 1444.7 1446.6 :Souris Westhope 1411.4 1411.4 1411.5 1412.1 1413.0 1415.7 1417.3 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: 04/01/2024 - 06/30/2024 LOCATION 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :Des Lacs Foxholm 1639.5 1639.3 1639.3 1639.2 1638.9 1638.8 1638.7 :Souris Sherwood 1606.8 1606.5 1606.3 1606.1 1605.8 1605.8 1605.8 Foxholm 1566.5 1566.5 1566.5 1566.5 1566.5 1566.5 1566.5 Minot 1551.3 1551.2 1551.0 1550.9 1550.8 1550.6 1550.6 Minot 1541.5 1541.5 1541.4 1541.3 1541.2 1541.1 1541.1 Logan 1521.9 1521.1 1520.2 1520.1 1520.0 1519.8 1519.8 Sawyer 1508.5 1507.9 1507.6 1507.1 1506.7 1506.6 1506.6 Velva 1492.3 1491.7 1491.2 1490.5 1490.2 1490.2 1490.2 :Wintering Karlsruhe 1503.6 1503.6 1503.5 1503.0 1503.0 1503.0 1503.0 :Souris Towner 1448.0 1446.7 1446.1 1445.3 1445.0 1444.7 1444.7 Bantry 1433.5 1432.4 1431.9 1431.1 1430.9 1430.7 1430.7 :Willow Creek Willow City 1437.0 1436.9 1436.7 1436.1 1436.1 1436.1 1436.1 :Souris Westhope 1410.4 1410.3 1410.3 1409.9 1409.6 1409.5 1409.4 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/bis for more weather and water information. The next outlook will be issued by the end of April. $$ Schlag