Flood Potential Outlook
Issued by NWS Bismarck, ND

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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


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