Flood Potential Outlook
Issued by NWS Bismarck, ND

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FGUS73 KBIS 272230
ESFBIS
NDC009-013-023-049-061-069-075-079-101-302200-

PROBABILISTIC HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE BISMARCK ND
430 PM CST MON DEC 27 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 late December through late March.

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 issuance of the monthly probabilistic hydrologic outlook does
encompass the earlier few weeks of the typical spring flood season
in its effective time period. Accordingly, this tends to raise the
probabilities in the below tables, more to timing than actual
snowpack. However, the region has indeed put on yet another blanket
of widespread snow over the Christmas holiday and that extra
water has not been included in the model runs for this outlook.
Importantly, there is still plenty of winter left for the snow to
either disappear due to sublimation, or for additional snow to add
to what has quickly become a memorable entry into winter. All that
aside, the general message to remember is that there is already
enough snow on the countryside to put the risk of spring flooding
at normal to above normal levels. The February issuance of the
Spring Flood and Hydrologic Resources Outlook will provide the best
assessment of the risk prior to the onset of the spring flood
season.

...Current Conditions...
Rivers, lakes, and reservoirs are near their normal
levels for this time of year with no significant concerns. Due to
the late November and Christmas storms, snow cover is not uniformly
distributed, but present across most of central and western North
Dakota. Soil moisture has also risen to something in the upper range
of normal to well above normal since mid-November as the result
of widespread rain and snow on warm ground in late November. Snow
water equivalent in the Souris River basin is higher in the southern
extent of the basin near Minot.

...Weather Outlook...
The near term 6-10 and 8-14 day outlooks depict a well above
normal chance for colder than normal temperatures and
precipitation. Looking out farther at the one-month outlook and
the region is still favored for below normal temperatures with
an equal chance for above normal, near normal, and below normal
precipitation. Even farther out, the three-month outlooks continue
to favor colder than normal temperatures with a slight
above normal probability of above normal precipitation.


...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: 12/25/2016 - 03/25/2017
                                       :    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    18    7   10   <5   <5   <5
  Minot 4NW       1562.0 1565.0 1570.0     8   <5   <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    13   <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 River
  Karlsruhe       1509.0 1511.0 1512.0    <5   <5   <5   <5   <5   <5
Souris River
  Towner          1454.0 1456.0 1458.0    55   17   17    5   <5   <5
  Bantry          1440.0 1441.0 1443.0    51   14   39    6   <5   <5
Willow Creek
  Willow City     1442.0 1446.0 1448.0    21    6   <5   <5   <5   <5
Souris River
  Westhope        1414.0 1418.0 1420.0    28    7   <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: 12/25/2016 - 03/25/2017
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Des/ Lacs River
Foxholm             1639.1 1639.1 1641.1 1645.2 1647.4 1649.0 1649.4
:Souris River
Sherwood            1606.1 1607.5 1611.5 1616.5 1618.4 1621.0 1622.0
Foxholm             1568.6 1568.7 1569.0 1570.0 1572.3 1575.9 1576.5
Minot 4NW           1551.7 1551.8 1552.6 1556.8 1558.8 1560.6 1563.1
Minot Brwy Brdg     1541.3 1541.5 1542.5 1544.5 1545.8 1547.1 1548.5
Logan               1522.2 1522.3 1524.0 1530.8 1534.4 1536.4 1536.9
Sawyer              1508.5 1508.7 1509.8 1517.0 1519.8 1522.0 1522.6
Velva               1492.2 1492.2 1492.8 1502.3 1505.1 1506.5 1506.8
:Wintering River
Karlsruhe           1502.8 1502.8 1503.0 1504.9 1507.3 1508.2 1508.6
:Souris River
Towner              1445.9 1446.0 1446.4 1454.2 1455.8 1456.5 1456.7
Bantry              1431.9 1432.0 1432.4 1440.1 1441.3 1441.9 1442.0
:Willow Creek
Willow City         1436.1 1436.1 1436.1 1437.0 1439.0 1443.2 1444.2
:Souris River
Westhope            1409.8 1409.8 1409.9 1412.1 1414.4 1416.1 1416.8

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: 12/25/2016 - 03/25/2017
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
Des Lacs River
  Foxholm           1639.0 1639.0 1639.0 1639.0 1639.0 1638.8 1638.8
Souris River
  Sherwood          1605.5 1605.5 1605.5 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         1550.8 1550.8 1550.7 1550.7 1550.7 1550.6 1550.6
  Minot Brwy Brdg   1537.1 1537.1 1536.7 1536.7 1536.6 1536.2 1536.1
  Logan             1519.9 1519.9 1519.9 1519.8 1519.8 1519.8 1519.8
  Sawyer            1506.7 1506.6 1506.6 1506.6 1506.6 1506.6 1506.6
  Velva             1490.2 1490.2 1490.2 1490.2 1490.2 1490.2 1490.2
Wintering River
  Karlsruhe         1502.8 1502.8 1502.8 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            1430.4 1430.4 1430.4 1430.4 1430.4 1430.3 1430.3
Willow Creek
  Willow City       1436.0 1436.0 1436.0 1436.0 1436.0 1436.0 1436.0
Souris River
  Westhope          1408.9 1408.9 1408.8 1408.8 1408.8 1408.8 1408.8

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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