Flood Potential Outlook
Issued by NWS Bismarck, ND
Issued by NWS Bismarck, ND
331
FGUS73 KBIS 222115
ESFBIS
NDC009-013-023-049-069-075-079-101-242100-
Probabilistic Hydrologic Outlook
National Weather Service Bismarck ND
415 PM CDT Thu Aug 22 2024
...FLOOD AND WATER RESOURCES OUTLOOK...
This Flood and Water Resources Outlook is for the Souris River Basin
of North Dakota, covering the period of 26 August through 24
November, 2024. This is a monthly issuance of the 90-day flood risks
for the Souris River Basin of North Dakota. These probabilities are
updated 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...
Risk of widespread flooding is at normal levels for this time of
year within the Souris River basin, which is actually quite low.
This does not suggest flooding cannot take place, but more that it
would take something very significant in the form of a thunderstorm
to initiate flooding along the Souris River and its forecast points.
...Snowpack Conditions...
No snow exists within the Souris River basin of North Dakota.
...Soil Conditions...
Soil moisture values across the Souris River Basin have been falling
over the past month due to lower than normal amounts of rain, and a
period of well above normal temperatures.
...Current Drought Conditions...
Drought, up to D1 (moderate drought) has been creeping into the
western portion of the Souris River Basin. Based on weather
forecasts and outlooks, the most likely future is one of drought
conditions becoming worse over the coming weeks and months.
...Reservoirs and Natural Wetlands...
All major natural wetlands and lakes have been resilient and are
near normal for this time of year. Man-made structures, such as Lake
Darling and the upstream Canadian reservoirs of Grant Devine and
Rafferty continue to fare well despite the intensifying drought in
the western portion of the basin.
...Weather Outlook...
The near term, 6-10 and 8-14 day outlooks favor near normal to below
normal temperatures with near normal precipitation in the 6-10 day
period and slightly favoring below normal precipitation in the 8-14
day outlook. In the longer term weeks 3-4 outlooks, a return to
above normal temperatures is favored with above normal temperatures.
Looking at the full month of September, there is an equal chances
designation for above normal, near normal, and below normal
temperatures and precipitation. Even longer term, the 3-month
outlook for September, October, and November favors above normal
temperatures with an equal chance of above normal, near normal, or
below normal precipitation.
...Ice Conditions...
No ice exists along the Souris River and its tributaries
in North Dakota.
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: 08/26/2024 - 11/24/2024
: 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 <5 <5 <5 <5 <5
Foxholm 1573.0 1576.0 1578.0 : <5 <5 <5 <5 <5 <5
Minot 1562.0 1565.0 1570.0 : <5 <5 <5 <5 <5 <5
Minot 1551.0 1553.0 1557.0 : <5 <5 <5 <5 <5 <5
Logan 1536.0 1538.0 1540.0 : <5 <5 <5 <5 <5 <5
Sawyer 1524.0 1526.0 1528.0 : <5 <5 <5 <5 <5 <5
Velva 1507.0 1512.0 1517.0 : <5 <5 <5 <5 <5 <5
:Wintering
Karlsruhe 1509.0 1511.0 1512.0 : <5 <5 <5 <5 <5 <5
:Souris
Towner 1454.0 1456.0 1458.0 : <5 <5 <5 <5 <5 <5
Bantry 1440.0 1441.0 1443.0 : <5 <5 <5 <5 <5 <5
:Willow Creek
Willow City 1442.0 1446.0 1448.0 : <5 6 <5 <5 <5 <5
:Souris
Westhope 1414.0 1418.0 1420.0 : <5 <5 <5 <5 <5 <5
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: 08/26/2024 - 11/24/2024
Location 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Des Lacs
Foxholm 1638.9 1638.9 1638.9 1638.9 1640.1 1640.9 1642.5
:Souris
Sherwood 1606.0 1606.0 1606.0 1606.6 1607.5 1610.3 1611.9
Foxholm 1566.5 1566.5 1566.5 1566.5 1566.5 1567.5 1570.4
Minot 1550.7 1550.7 1550.7 1550.8 1551.2 1551.8 1554.0
Minot 1541.1 1541.1 1541.1 1541.2 1541.5 1541.7 1542.7
Logan 1519.8 1519.8 1519.8 1520.0 1521.3 1523.9 1526.6
Sawyer 1506.6 1506.6 1506.6 1506.9 1508.1 1510.1 1512.9
Velva 1490.2 1490.2 1490.2 1490.4 1492.0 1493.1 1497.5
:Wintering
Karlsruhe 1503.0 1503.0 1503.0 1503.0 1504.2 1505.1 1506.5
:Souris
Towner 1445.8 1445.8 1445.8 1445.8 1446.6 1449.8 1453.6
Bantry 1431.7 1431.7 1431.7 1431.7 1432.4 1435.5 1439.7
:Willow Creek
Willow City 1437.0 1437.0 1437.0 1437.0 1437.3 1439.1 1441.3
:Souris
Westhope 1411.3 1411.3 1411.3 1411.3 1411.3 1412.2 1413.4
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: 08/26/2024 - 11/24/2024
LOCATION 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Des Lacs
Foxholm 1638.8 1638.8 1638.7 1638.7 1638.7 1638.7 1638.7
:Souris
Sherwood 1605.8 1605.8 1605.8 1605.8 1605.8 1605.8 1605.8
Foxholm 1566.5 1566.5 1566.5 1566.5 1566.5 1566.5 1566.5
Minot 1550.7 1550.6 1550.6 1550.6 1550.6 1550.6 1550.6
Minot 1541.1 1541.1 1541.1 1541.0 1541.0 1541.0 1541.0
Logan 1519.8 1519.8 1519.8 1519.7 1519.7 1519.7 1519.7
Sawyer 1506.6 1506.6 1506.6 1506.5 1506.5 1506.5 1506.5
Velva 1490.2 1490.2 1490.2 1490.2 1490.2 1490.2 1490.2
:Wintering
Karlsruhe 1503.0 1503.0 1503.0 1503.0 1503.0 1503.0 1503.0
:Souris
Towner 1445.0 1445.0 1444.8 1444.7 1444.7 1444.7 1444.7
Bantry 1431.0 1430.9 1430.8 1430.7 1430.7 1430.7 1430.7
:Willow Creek
Willow City 1436.7 1436.7 1436.5 1436.1 1436.1 1436.1 1436.1
:Souris
Westhope 1410.0 1410.0 1409.9 1409.8 1409.7 1409.7 1409.7
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 September.
$$
Schlag