Flood Potential Outlook
Issued by NWS Bismarck, ND

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FGUS73 KBIS 292139
ESFBIS

NDC009-013-023-049-061-069-075-079-101-302200-

PROBABILISTIC HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE BISMARCK ND
440 PM CDT FRI APR 29 2016

...Flood and Water Resources Outlook...

This probability based Flood and Water Resources Outlook is
for the Souris (Mouse) River basin of North Dakota and covers the
period of early May through late July.

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...
This outlook contains the probabilities for reaching flood stage
at the forecast points within the Souris River basin of North Dakota.
The Souris River basin remains well below normal with respect to
flood risk with the exception of the Willow Creek sub basin. At this
point, strong thunderstorms producing localized flooding is the
primary source of the existing flood risks.

...Current Conditions...
Despite recent widespread rains, rivers and streams tend to be near
the low end of normal. A fairly dry soil profile coming into April
absorbed the vast majority of recent rains. At this point, soil
moisture levels are much closer to normal levels and any heavy rains
in the near term should be expected to produce greater runoff but
risks associated with widespread flooding are still considered below
normal.

...Weather Outlook...
The month of April has generally been wet across the Souri River
basin of North Dakota. In the near term 6-10 and 8 - 14 day outlooks,
the expectation is for above normal temperatures and a
below normal chance of precipitation. This transitions into an above
normal chance for above normal temperatures and an equal chance for
above normal, near normal, or below normal precipitation pattern in
the one and three month outlooks.

...Important Note On Substantive Changes... Beginning January 1st of
2016, the National Weather Service converted all river gage data in
the Souris River basin of North Dakota to feet above Mean Sea Level
using the North American Vertical Datum of 1988. This included raises
in flood stage definitions by up to one foot at individual locations
in order to continue working with whole numbers. More information on
this can be found on our website, or by contacting Service Hydrologist
Allen Schlag at 701-250-4495.

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: 05/01/2016 - 07/30/2016

                                       :    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         1651.0 1653.0 1654.0    <5   <5   <5   <5   <5   <5
Souris River
  Sherwood        1623.0 1625.0 1630.0    <5   <5   <5   <5   <5   <5
  Foxholm         1573.0 1576.0 1578.0    <5   24   <5    6   <5   <5
  Minot 4NW       1562.0 1565.0 1570.0    <5    8   <5   <5   <5   <5
  Minot Brwy Brdg 1551.0 1553.0 1557.0    <5   <5   <5   <5   <5   <5
  Logan           1536.0 1538.0 1540.0    <5   10   <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    9   <5   <5   <5   <5
Wintering River
  Karlsruhe       1509.0 1511.0 1512.0    <5   <5   <5   <5   <5   <5
Souris River
  Towner          1454.0 1456.0 1458.0    13   43   <5   17   <5   <5
  Bantry          1440.0 1441.0 1443.0    13   42    8   26   <5   <5
Willow Creek
  Willow City     1442.0 1446.0 1448.0     9   26    6    7   <5   <5
Souris River
  Westhope        1414.0 1418.0 1420.0     9   39    5   15   <5   10

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: 05/01/2016 - 07/30/2016
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Des/ Lacs River
Foxholm             1639.5 1639.5 1639.5 1640.7 1641.9 1643.1 1643.9
:Souris River
Sherwood            1606.5 1606.5 1606.9 1608.3 1611.5 1615.3 1618.5
Foxholm             1566.6 1566.6 1566.6 1566.6 1570.4 1571.0 1572.8
Minot 4NW           1551.1 1551.1 1551.1 1551.6 1553.9 1555.0 1556.7
Minot Brwy Brdg     1538.4 1538.4 1538.7 1541.1 1543.0 1543.4 1544.4
Logan               1520.1 1520.1 1520.3 1522.8 1525.9 1528.0 1532.2
Sawyer              1507.5 1507.5 1507.6 1509.3 1511.4 1514.3 1518.5
Velva               1491.5 1491.5 1491.7 1492.9 1496.0 1499.8 1504.2
:Wintering River
Karlsruhe           1504.1 1504.1 1504.1 1504.2 1504.8 1506.7 1507.9
:Souris River
Towner              1445.8 1445.8 1445.8 1448.4 1452.0 1455.0 1455.7
Bantry              1431.8 1431.8 1431.8 1434.0 1437.4 1440.7 1441.3
:Willow Creek
Willow City         1438.8 1438.8 1438.8 1438.8 1438.8 1441.6 1446.6
:Souris River
Westhope            1410.7 1410.7 1410.7 1410.8 1411.7 1413.7 1418.1

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: 05/01/2016 - 07/30/2016
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
Des Lacs River
  Foxholm           1639.4 1639.3 1639.2 1639.0 1639.0 1639.0 1639.0
Souris River
  Sherwood          1606.2 1606.1 1605.6 1605.5 1605.5 1605.5 1605.5
  Foxholm           1566.6 1566.6 1566.6 1566.6 1566.6 1566.6 1566.6
  Minot 4NW         1551.0 1551.0 1550.9 1550.7 1550.6 1550.6 1550.6
  Minot Brwy Brdg   1538.1 1537.9 1537.2 1536.6 1536.2 1536.2 1536.2
  Logan             1520.1 1520.1 1519.9 1519.8 1519.7 1519.7 1519.7
  Sawyer            1507.3 1507.1 1506.7 1506.6 1506.5 1506.5 1506.5
  Velva             1491.2 1490.8 1490.2 1490.2 1490.2 1490.2 1490.2
Wintering River
  Karlsruhe         1503.5 1503.2 1502.9 1502.8 1502.8 1502.8 1502.8
Souris River
  Towner            1444.4 1444.4 1444.4 1444.4 1444.4 1444.4 1444.4
  Bantry            1430.6 1430.6 1430.6 1430.6 1430.6 1430.5 1430.5
Willow Creek
  Willow City       1436.7 1436.3 1436.0 1436.0 1436.0 1436.0 1436.0
Souris River
  Westhope          1410.1 1410.1 1409.5 1409.2 1409.2 1409.2 1409.2

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.

$$
ajs


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