Flood Potential Outlook
Issued by NWS Bismarck, ND

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FGUS73 KBIS 231802
ESFBIS
NDC009-013-023-049-061-069-075-079-101-302200-

PROBABILISTIC HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE BISMARCK ND
101 PM CDT THU JUL 23 2015

...Flood and Water Resources Outlook...

This probablistic flood outlook is for the Souris (Mouse) River
basin of North Dakota and covers the period of late Juy through
late October.

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...
In general, risks presented below tend to reflect a seasonally
normal probability of flooding. At this point of the summer,
localized thunderstorms with low to moderate spatial coverage
tend to present the majority of the flood risk and is more of a
problem along the coulees and other small drainages than the Souris
River iteslf.

...Current Conditions...
The Souris River tends to be fairly normal with respect to flow along
its path through North Dakota with little threat of seeing that
change in the near term.

...Weather Outlook...
The near term, 6-10 and 8-14 day outlooks show the region has a
slightly greater than normal chance of below normal precipitation.
Looking longer into the climate outlooks, there is no
strong climate driver in place affecting the North Dakota area.
Hence, the outlook is generally of an equal chance for below normal,
near normal, or above normal temperatures and precipitation.


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 of the model
predicting a rise to 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:  7/27/2015 - 10/25/2015

                                       :    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 River
  Foxholm           16.0   18.0   19.0 :  <5   <5   <5   <5   <5   <5
Souris River
  Sherwood          18.0   20.0   25.0 :  <5   <5   <5   <5   <5   <5
  Foxholm           10.0   13.0   15.0 :  <5   <5   <5   <5   <5   <5
  Minot 4NW         14.0   17.0   22.0 :  <5    5   <5   <5   <5   <5
  Minot Brwy Brdg 1549.0 1551.0 1555.0 :  <5   <5   <5   <5   <5   <5
  Logan             34.0   36.0   38.0 :  <5    5   <5   <5   <5   <5
  Sawyer            22.0   24.0   26.0 :  <5   <5   <5   <5   <5   <5
  Velva           1505.0 1510.0 1515.0 :  <5   <5   <5   <5   <5   <5
Wintering River
  Karlsruhe          7.0    9.0   10.0 :  <5   <5   <5   <5   <5   <5
Souris River
  Towner            52.0   54.0   56.0 :  <5   10   <5   <5   <5   <5
  Bantry            11.0   12.0   14.0 :  <5    8   <5   <5   <5   <5
Willow Creek
  Willow City       10.0   14.0   16.0 :  <5    6   <5   <5   <5   <5
Souris River
  Westhope          10.0   14.0   16.0 :  <5    9   <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:  7/27/2015 - 10/25/2015
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Des Lacs River
Foxholm               5.0    5.0    5.0    5.0    5.9    7.1    7.8
:Souris River
Sherwood              1.9    1.9    1.9    2.3    4.4    6.0    7.0
Foxholm               6.7    6.7    6.7    6.9    7.4    7.6    7.7
Minot 4NW             4.9    4.9    4.9    5.0    5.4    5.6    5.7
Minot Brwy Brdg    1540.5 1540.5 1540.6 1540.7 1541.2 1541.3 1541.4
Logan                21.4   21.4   21.5   21.9   22.7   23.2   24.7
Sawyer                7.6    7.6    7.7    8.0    8.6    9.5   11.3
Velva              1491.2 1491.2 1491.2 1491.5 1491.8 1493.7 1495.2
:Wintering River
Karlsruhe             1.6    1.6    1.6    1.9    2.9    3.6    3.9
:Souris River
Towner               45.2   45.2   45.4   46.2   47.5   50.0   51.8
Bantry                3.2    3.2    3.3    3.9    5.2    7.6    9.8
:Willow Creek
Willow City           4.8    4.8    4.8    4.9    5.7    7.0    8.2
:Souris River
Westhope              7.4    7.4    7.4    7.4    7.4    8.5    9.0

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:  7/27/2015 - 10/25/2015
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
Des Lacs River
  Foxholm             4.6    4.6    4.6    4.6    4.7    4.8    4.8
Souris River
  Sherwood            1.6    1.6    1.6    1.6    1.6    1.7    1.8
  Foxholm             4.5    4.5    4.5    4.5    4.5    4.5    4.5
  Minot 4NW           3.8    3.8    3.8    3.8    3.9    3.9    3.9
  Minot Brwy Brdg  1535.4 1535.4 1535.4 1535.4 1535.8 1536.0 1536.1
  Logan              18.6   18.6   18.6   18.6   18.7   18.7   18.7
  Sawyer              5.4    5.4    5.4    5.4    5.4    5.5    5.5
  Velva            1489.0 1489.0 1489.0 1489.0 1489.0 1489.0 1489.0
Wintering River
  Karlsruhe           1.6    1.6    1.6    1.6    1.6    1.6    1.6
Souris River
  Towner             43.2   43.2   43.2   43.2   43.2   43.3   43.5
  Bantry              1.7    1.7    1.7    1.7    1.7    1.7    1.8
Willow Creek
  Willow City         4.6    4.6    4.6    4.6    4.6    4.6    4.6
Souris River
  Westhope            5.6    5.6    5.6    5.7    5.7    5.8    6.0

These long-range probabilistic outlooks contain forecast values that
are calculated using historical conditions from 30 or more years of
climatological data...and 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 toward the end of next month.

$$



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