...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.
...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.
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