####018011993#### FGUS73 KBIS 151347 ESFBIS NDC009-013-023-049-069-075-079-101-171400- Probabilistic Hydrologic Outlook National Weather Service Bismarck ND 747 AM CST Thu Feb 15 2024 ZCZC BISWRKESF 142314 TTAA00 KBIS DDHHMM NDC009-013-023-049-069-075-079-101-271800- Probabilistic Hydrologic Outlook National Weather Service Bismarck ND 1207 PM CST Thu Jan 25 2024 ...SPRING FLOOD AND WATER RESOURCES OUTLOOK... This Spring Flood and Water Resources Outlook is for the Souris River basin of North Dakota, covering the period of 19 February through 19 May, 2024. This is the first of a three-part Spring Flood and Water Resources Outlook series. 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 flood risks within the Souris River Basin of North Dakota are well below normal in the upstream forecast locations, and slightly below normal in the most downstream forecast locations of Towner and Bantry. While the overall risk for widespread flooding is below normal, recent snowmelt in the southern part of the Souris River Basin has wetted the surface of the ground and created a near impermeable layer of frozen soil that can lead to significantly enhanced runoff in the event of an early spring rain. This enhanced risk will remain in place until such time as the soils begin to thaw, most likely in March. Overall though, drought concerns also remain elevated and should probably be considered at least as great of a risk as problematic high water. Quite simply, the lack of Snow-Water Equivalent (SWE) on the countryside is reflected in the below normal flood risk. ...Snowpack Conditions... Overall SWE content of the snowpack across the Souris River Basin of North Dakota is below, to well below normal for this time of year. Most of the Souris River Basin has well under an inch of SWE with one-quarter to one-half of an inch common. That being said, all it would take is one significant snow storm to bring the SWE up to around 1.5 inches of water, which is roughly normal for much of the Souris River Basin of North Dakota. Note: There is no such storm in the current forecast, nor do the climate outlooks suggest an unusual risk for such an event. ...Soil Conditions... Soil moisture values across the Souris River Basin are very high in the soil down to about 4 inches (0-10 cm), but begin to fall rapidly with depth to more normal values at a depth of around 40 inches (100 cm). Frost depth is highly variable this year as a mix of very warm weather in December and a good part of January has helped prevent extensive freezing of the soil, but up to 30 inches of frost depth has been observed in some areas. ...Current Drought Conditions... The U.S. Drought Monitor reflects D0 (Abnormally Dry) in the western portion of the Souris River Basin of North Dakota which increases to D2 (Severe Drought) in Towner County. 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 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 their full flood control storage available for spring runoff. The majority of natural wetlands and lakes also are at, or near normal water levels for this time of year as the drier than normal latter half of summer and early fall took a toll on water levels in 2023. ...Weather Outlook... The Climate Prediction Center 6-10 day outlooks favor warmer and drier than normal, while the 8-14 day outlooks hold the favoring for warmer than normal, but precipitation goes to the near normal category. The outlooks for the entire month of February is for an above normal temperature outcome with precipitation being in the equal chances category for above normal, near normal, or below normal precipitation. The longer term three-month outlook for February, March and April continues the favoring for above normal temperatures and equal chances designation for precipitation. In general, this somewhat suggests there's an overall favoring for an earlier than normal spring melt season, but does not rule out a late spring snowstorm. ...Ice Conditions... After recent warm weather, not all rivers remain covered in ice. Lakes and wetlands are generally still ice covered, but thickness is generally less than normal and reports of an early softening of ice, especially near the shoreline, are common. ...Spring Flood Outlook Release Dates... The NWS has set the release dates for the Spring Flood and Water Resources Outlook series as follows: First issuance: February 15, 2024 First update: February 29, 2024 Final update: March 14, 2024 After the official Spring Flood and Water Resource Outlook series, the NWS will return to its routine, monthly issuance of Flood and Water Resource Outlooks on March 28, 2024 unless the spring melt is already in full swing. 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: 02/19/2024 - 05/19/2024 : 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 10 <5 5 <5 <5 Foxholm 1573.0 1576.0 1578.0 : 19 37 6 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 : 9 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 : 8 16 <5 <5 <5 <5 :Wintering Karlsruhe 1509.0 1511.0 1512.0 : 13 14 <5 <5 <5 <5 :Souris Towner 1454.0 1456.0 1458.0 : 47 55 12 28 <5 <5 Bantry 1440.0 1441.0 1443.0 : 50 55 25 40 <5 8 :Willow Creek Willow City 1442.0 1446.0 1448.0 : 41 47 6 19 <5 <5 :Souris Westhope 1414.0 1418.0 1420.0 : 13 49 <5 21 <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: 02/19/2024 - 05/19/2024 Location 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :Des Lacs Foxholm 1640.2 1640.7 1641.1 1641.8 1643.7 1645.6 1647.5 :Souris Sherwood 1610.6 1610.9 1612.1 1614.8 1618.6 1619.9 1621.8 Foxholm 1570.3 1570.9 1571.0 1571.0 1571.6 1573.9 1576.6 Minot 1553.8 1554.2 1554.3 1554.6 1556.0 1557.7 1564.3 Minot 1542.6 1542.8 1542.9 1543.1 1543.8 1545.0 1548.4 Logan 1526.0 1526.6 1526.8 1527.3 1530.0 1534.8 1537.5 Sawyer 1511.5 1512.0 1512.3 1512.9 1516.2 1520.3 1523.5 Velva 1495.4 1496.0 1496.3 1497.0 1501.3 1505.6 1507.9 :Wintering Karlsruhe 1503.9 1504.0 1504.2 1507.2 1508.0 1509.2 1509.3 :Souris Towner 1450.0 1451.5 1452.4 1453.9 1455.0 1456.3 1457.2 Bantry 1435.4 1436.7 1437.9 1440.0 1441.0 1441.9 1442.7 :Willow Creek Willow City 1437.5 1437.6 1437.9 1440.5 1444.0 1444.8 1446.5 :Souris Westhope 1410.8 1411.1 1411.6 1412.3 1413.1 1414.2 1417.0 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: 02/19/2024 - 05/19/2024 LOCATION 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :Des Lacs Foxholm 1638.9 1638.9 1638.9 1638.8 1638.8 1638.8 1638.7 :Souris Sherwood 1606.3 1606.2 1606.2 1606.2 1606.1 1606.1 1606.1 Foxholm 1566.9 1566.5 1566.5 1566.5 1566.5 1566.5 1566.5 Minot 1550.9 1550.9 1550.8 1550.8 1550.7 1550.7 1550.6 Minot 1541.4 1541.3 1541.3 1541.2 1541.2 1541.1 1541.1 Logan 1520.3 1520.2 1520.1 1520.0 1519.9 1519.9 1519.8 Sawyer 1507.7 1507.5 1507.0 1506.7 1506.7 1506.6 1506.6 Velva 1491.5 1491.1 1490.5 1490.2 1490.2 1490.2 1490.2 :Wintering Karlsruhe 1503.3 1503.3 1503.3 1503.2 1503.0 1503.0 1503.0 :Souris Towner 1444.4 1444.4 1444.4 1444.4 1444.4 1444.4 1444.4 Bantry 1430.2 1430.2 1430.2 1430.2 1430.2 1430.2 1430.2 :Willow Creek Willow City 1436.7 1436.7 1436.7 1436.6 1436.3 1436.1 1436.1 :Souris Westhope 1410.0 1409.9 1409.7 1409.4 1409.2 1409.1 1409.1 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/bis for more weather and water information. The next outlook will be issued on February 29th, 2024 $$ Schlag