National Weather Service United States Department of Commerce

Areas of Excessive Rainfall Today; Dangerous Heat Redeveloping Over the Southwest; Dry Thunderstorms in the Great Basin

Heavy to excessive rainfall may bring flooding today to parts of the southern Rockies, eastern Mid-Atlantic, and ArkLaTex regions. Dangerous heat will redevelop Friday through this weekend into next week over much of southern California and the Desert Southwest. Dry thunderstorms continue to pose a threat for new wildfire starts across parts of the Great Basin today and Friday. Read More >

Missouri and James River Basins

 

...SPRING FLOOD AND WATER RESOURCES OUTLOOK...

This probabilistic Flood and Water Resources outlook is for
the Missouri and James River basins of North Dakota and covers
the period of late March through late June.

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 risk of flooding this spring has changed remarkably after
the past couple of wet weeks, but risks are still not considered
overly threatening. Perhaps the most notable change is found
in the upper James River Basin of North Dakota where there is
more snow on the ground.  Other places, like those west of the
Missouri River, have received fair amounts of moisture over the
past couple of weeks, but have also slowly melted a good fraction
of it off under very favorable conditions. Much of the risk for
flooding in the below tables is due to the hydrologic models
use of climatologically normal temperature ranges that would
encourage a rapid melt. However, no forecast or outlook for
temperatures suggest a rapid rise to above normal temperatures.
Hence, a continuation of slightly below normal temperatures for now
will help slowly melt the existing snowpack, and in turn, lessen
the overall risk of widespread problems.

One of the items of interest not included in the tables below is the
runoff for the Missouri and Yellowstone Rivers. Mountain snowpack in
the headwaters of both the Yellowstone and Missouri River basins is
above normal. However, as noted in the prior issuances of
this outlook, this alone does not suggest a troublesome runoff
event, as prior high runoff years included significant spring rains
on the plains of Montana and North Dakota.

High water due to ice jams is also not included in the below tables.
While there are no indications that ice jams will be a major problem
on the small streams, the Yellowstone and Missouri Rivers above
Williston have some risk of ice jams. The plains of Montana have
begun to see meltwater in their streams with at least some
expectation for ice problems along the Yellowstone River, which will
eventually work their way towards North Dakota.

...Current Conditions...
Rivers, lakes, and reservoirs have started to slowly come to life
during this third week of March. Thus far, river rises have been
minimal and pose no threat. They do however suggest that pathways
for rain and meltwater are being cleared and will provide more
efficient transport. Snow cover in the southwestern corner of the
state remains below normal, but increases as one goes east of
the Missouri River. The upper reaches of the James River basin
contains what is probably the highest snow water equivalent (SWE)
at around two inches.  However, even in areas that have decent
snowpack, the liquid equivalent is much below that of recent
problematic springs. Soil moisture levels also remain well below
normal across the state, and wetlands tend to be down from prior
years due to precipitation deficits last summer. Frost
depth is significant in many areas, but soil temperatures are
rising and should help encourage infiltration of meltwater under
most melt scenarios.

...Weather Outlook... The near term 6-10 and 8-14 day outlooks
depict a well above normal chance for colder than normal
temperatures with near normal precipitation. The one-month and
three-month outlooks favor cooler than normal temperatures and
above normal 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 a 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.


                 Chance of Exceeding Stages at Specific Locations
                     Valid Period:  03/25/2018  - 06/23/2018

                                       :    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
--------           -----  -----  ----- : ---  ---  ---  ---  ---  ---
:Pipestem Creek
Pingree             11.0   13.0   15.0 :  54   12   <5   <5   <5   <5
:James River
Grace City          12.0   14.0   15.0 :  61   15   28    8   17    7
Lamoure             14.0   16.0   18.0 :  32    9   20    5   14   <5
:Cannonball River
Regent              22.0   24.0   26.0 :  <5   <5   <5   <5   <5   <5
:Cedar Creek
Raleigh             12.0   14.0   16.0 :  <5   <5   <5   <5   <5   <5
:Cannonball River
Breien              10.0   20.0   23.0 :  26   37   <5   <5   <5   <5
:Beaver Creek
Linton              12.0   14.0   16.0 :  13   33   <5    7   <5   <5
:Little Muddy River
Williston           10.0   12.0   14.0 :  10   46   <5   28   <5   14
:Little Missouri
Marmarth            18.0   23.0   30.0 :  <5    5   <5   <5   <5   <5
:Little Missouri River
Medora              15.0   18.0   20.0 :  20    7    8    5   <5    5
Watford City        20.0   24.0   30.0 :  <5   <5   <5   <5   <5   <5
:Knife River
Manning             15.0   17.0   20.0 :  15   23   <5   <5   <5   <5
:Spring Creek
Zap                 14.0   18.0   20.0 :  15   24    8    9    7    6
:Knife River
Hazen               21.0   24.0   25.0 :  18   36   15   18    7   11
:Heart River
Mandan              17.0   23.0   28.0 :  12    9   <5   <5   <5   <5
:Apple Creek
Menoken             15.0   16.0   17.0 :  39   53   29   47    6   28

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: 03/25/2018  - 06/23/2018
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Pipestem Creek
Pingree              10.0   10.4   10.7   11.1   11.6   12.3   12.9
:James River
Grace City           10.1   10.8   11.4   12.8   14.1   18.2   20.9
Lamoure               9.3    9.4    9.5   10.0   15.3   18.1   18.3
:Cannonball River
Regent                6.2    6.2    6.3    7.7    9.6   12.0   12.5
:Cedar Creek
Raleigh               3.0    3.0    3.6    4.5    6.5    7.5    8.8
:Cannonball River
Breien                5.8    5.8    6.2    7.8   10.1   12.8   15.1
:Beaver Creek
Linton                5.1    5.3    5.8    6.6    8.9   13.0   13.7
:Little Muddy River
Williston             4.7    4.7    5.1    6.8    8.0   10.0   11.5
:Little Missouri
Marmarth              4.7    4.8    5.7    8.1   12.5   15.3   17.1
:Little Missouri River
Medora                6.2    6.3    6.9    9.2   13.4   17.0   18.8
Watford City          2.5    2.6    3.2    4.9    8.8   12.3   14.0
:Knife River
Manning               7.5    7.5    8.4    9.6   12.6   15.9   16.1
:Spring Creek
Zap                   6.7    7.2    8.0   10.0   12.8   17.1   25.1
:Knife River
Hazen                 6.0    6.4    9.1   13.3   19.4   24.3   26.3
:Heart River
Mandan                4.6    6.2    7.5    9.5   11.8   17.4   21.5
:Apple Creek
Menoken               9.1    9.8   11.1   12.9   16.2   16.6   17.1

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:  03/25/2018  - 06/23/2018
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Pipestem Creek
Pingree               4.6    4.6    4.6    4.6    4.6    4.6    4.6
:James River
Grace City            4.0    4.0    4.0    4.0    4.0    4.0    4.0
Lamoure               6.8    6.8    6.8    6.8    6.8    6.8    6.8
:Cannonball River
Regent                4.8    4.8    4.7    4.6    4.5    4.5    4.5
:Cedar Creek
Raleigh               1.0    0.9    0.8    0.6    0.3    0.3    0.3
:Cannonball River
Breien                2.8    2.7    2.6    2.5    2.4    2.4    2.4
:Beaver Creek
Linton                4.3    4.3    4.3    4.3    4.3    4.3    4.3
:Little Muddy River
Williston             4.7    4.7    4.6    4.6    4.5    4.4    4.4
:Little Missouri
Marmarth              1.7    1.6    1.5    1.3    1.3    1.2    1.2
:Little Missouri River
Medora                2.3    2.3    2.1    1.9    1.9    1.8    1.7
Watford City          0.1    0.1   -0.1   -0.2   -0.3   -0.4   -0.4
:Knife River
Manning               6.4    6.4    6.4    6.3    6.3    6.3    6.3
:Spring Creek
Zap                   4.9    4.9    4.9    4.9    4.8    4.8    4.8
:Knife River
Hazen                 1.1    1.1    1.1    1.1    0.9    0.9    0.9
:Heart River
Mandan               -0.1   -0.1   -0.2   -0.4   -0.5   -0.6   -0.7
:Apple Creek
Menoken               5.0    5.0    5.0    5.0    4.9    4.7    4.6

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 April 26th.

 

 

 

Souris (Mouse) River Basin


...SPRING 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 March through late June.

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 recent snowy weather has added what can best be called beneficial
moisture to the Souris River basin, but has not significantly changed
the prospects for flooding. All river forecast locations remain below
historical risks for flooding with most being well below normal.

This does not suggest though that there will be no episodes of high
water, only that any problematic high water should be relatively
isolated, minor in nature, and the result of heavy spring rains.

...Current Conditions...
Lake Darling, Rafferty Reservoir, and Grant Devine (formerly
known as Alameda Reservoir) are all at or below their normal
winter levels. Small rivers also remain slightly below normal to
near normal for this time of year. Wetlands, after a dry summer
and fall, tend to have slightly lower water levels than the past
several years. Similarly, soil moisture levels are below normal to
well below normal. Snow cover, while greater than that of a couple
weeks ago is still below normal amounts going into the spring melt.

One flood risk not included in the below tables is that resulting
from ice jams. While ice jams and the high water they can cause
are not mathematically predictable, a lack of strong runoff due to
melting snow minimizes the risk of ice jams.

...Weather Outlook...
The near term 6-10 and 8-14 day outlooks depict a well above
normal chance for colder than normal temperatures with near normal
precipitation. The one-month and three-month outlooks favor cooler
than normal temperatures and 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 had 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: 03/25/2018 - 06/23/2018
                                       :    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   11   <5   <5   <5   <5
  Foxholm         1573.0 1576.0 1578.0     9   32   <5   12   <5   <5
  Minot 4NW       1562.0 1565.0 1570.0    <5   11   <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     8   16   <5   <5   <5   <5
  Sawyer          1524.0 1526.0 1528.0    <5    7   <5   <5   <5   <5
  Velva           1507.0 1512.0 1517.0     5   14   <5   <5   <5   <5
Wintering River
  Karlsruhe       1509.0 1511.0 1512.0    <5    6   <5   <5   <5   <5
Souris River
  Towner          1454.0 1456.0 1458.0    28   61   10   24   <5    5
  Bantry          1440.0 1441.0 1443.0    28   59   19   38   <5    6
Willow Creek
  Willow City     1442.0 1446.0 1448.0    11   38   <5   14   <5   <5
Souris River
  Westhope        1414.0 1418.0 1420.0    19   46    5   23   <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: 03/25/2018 - 06/23/2018
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Des/ Lacs River
Foxholm             1641.3 1641.5 1641.8 1642.2 1643.1 1646.1 1647.8
:Souris River
Sherwood            1610.7 1610.8 1611.7 1612.8 1615.3 1618.0 1620.7
Foxholm             1567.2 1569.1 1570.3 1570.9 1571.3 1572.2 1576.0
Minot 4NW           1552.0 1552.2 1553.4 1554.3 1555.0 1560.3 1561.5
Minot Brwy Brdg     1542.1 1542.2 1542.9 1543.2 1543.3 1546.5 1547.4
Logan               1523.4 1523.6 1525.7 1526.9 1528.0 1535.0 1536.7
Sawyer              1509.7 1509.8 1511.3 1512.5 1513.8 1520.6 1522.5
Velva               1492.9 1493.1 1495.6 1496.7 1499.7 1505.5 1507.4
:Wintering River
Karlsruhe           1504.8 1505.0 1505.2 1505.4 1506.0 1508.2 1508.9
:Souris River
Towner              1447.5 1448.5 1451.3 1452.8 1454.9 1456.0 1456.9
Bantry              1433.2 1434.1 1436.5 1438.4 1440.7 1441.5 1442.3
:Willow Creek
Willow City         1437.1 1437.2 1437.4 1437.7 1438.3 1443.3 1445.6
:Souris River
Westhope            1410.8 1411.0 1411.3 1412.3 1413.5 1415.7 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: 03/25/2018 - 06/23/2018
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
Des Lacs River
  Foxholm           1638.8 1638.8 1638.8 1638.8 1638.8 1638.8 1638.8
Souris River
  Sherwood          1605.6 1605.6 1605.6 1605.6 1605.5 1605.5 1605.5
  Foxholm           1566.5 1566.5 1566.5 1566.5 1566.5 1566.5 1566.5
  Minot 4NW         1550.5 1550.5 1550.5 1550.5 1550.5 1550.5 1550.5
  Minot Brwy Brdg   1536.6 1536.1 1533.5 1533.5 1533.5 1533.5 1533.5
  Logan             1519.9 1519.9 1519.9 1519.8 1519.6 1519.2 1519.2
  Sawyer            1506.7 1506.6 1506.6 1506.5 1506.5 1506.2 1506.2
  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 1430.4 1430.4
Willow Creek
  Willow City       1435.5 1435.5 1435.5 1435.5 1435.5 1435.5 1435.5
Souris River
  Westhope          1409.0 1409.0 1409.0 1409.0 1409.0 1409.0 1409.0

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 on April 26th.