Flood Potential Outlook
Issued by NWS Omaha/Valley, NE

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NEC003-023-025-037-039-053-055-067-095-107-109-119-127-139-141-143-
147-151-153-155-159-167-173-IAC071-085-133-137-145-155-202110-

PROBABILISTIC HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
310 PM CST THU FEB 19 2015

...Spring Flood and Water Resources Outlook #1...

This flood outlook is for the National Weather Service (NWS)
Omaha/Valley Hydrologic Services Area.  This area includes eastern
Nebraska and portions of southwest Iowa. It includes portions of
the following rivers and their tributaries.

Missouri River from Decatur to Rulo
Niobrara River from Verdel to the Missouri River
Big Blue River from Surprise to the Kansas border
Elkhorn River from Neligh to the Platte River confluence
Platte River from Duncan to the Missouri River confluence
Other tributaries to the Missouri River in Iowa and Nebraska

               ** Current Flood Outlook Highlights **

* The risk of flooding for the remainder of winter and into
mid-spring is near to below normal. Locally heavy spring rains will
cause flooding in localized areas as is the case every year. This
outlook is directed towards flooding on a larger scale.

* Current conditions are not conducive to major, large-scale
flooding.

* The threat for localized ice jam flooding is below normal.

* Graphics for select river gauges are available on our website at:
http://water.weather.gov/ahps2/index.php?wfo=oax

* The next outlook will be issued on March 5th.

.Overview: A meager snowpack, shallow frost depths and lack of
widespread significant fall/winter precipitation all indicate a low
threat for large-scale spring flooding.

.Mountain Snowpack: The latest snow water equivalent observations
indicate the mountain snowpack is just below average for this time
of year for the Missouri River headwaters. By February 15, normally
70% of the peak water equivalent has accumulated. For the Platte
River the mountain snowpack is a little more below average with most
basins reporting 75-85% of average.

.Plains Snowpack: Through mid-February, the Plains snowpack is
widespread but snow water equivalent values are low. In its
current state, the snowmelt from this snowpack would not appreciably
increase the spring flood threat.

.Ice Jam Threat: Several ice jams have already occurred this winter.
Most have been minor but some flooding of low-lying areas have
occurred. Along the usual ice jam prone rivers a majority of the ice
has already moved out with only frazil, or slush, ice remaining. This
frazil ice could still cause a minor ice jam,especially along the
Platte and Elkhorn rivers. But overall we would categorize the
remaining ice jam threat as low.

.Frost Depths: The latest reports indicate frost depths are around a
half foot across the area. Frost depths have decreased over the past
few weeks due to a couple warm spells. Due to frost depths being
fairly shallow across the area, they should not contribute to the
flood threat unless heavy rain were to fall on the ground before it
thaws completely.

.Current River Conditions: Due to remnant ice cover current flow
values are hard to come by across the area. What flow values are
available indicate area rivers are generally near normal. The
Missouri River is running above normal, largely due to slightly
above normal releases from Gavins Point Dam.

.Climate Outlook for the next two weeks (through March 4th): There
is a 40 to 50% chance for temperatures to be below-normal and a 33%
chance for precipitation to be near to below-normal.

.Climate Outlook for March: The Climate Prediction Center predicts
an equal chance for temperatures and precipitation to be below, near
or above normal.

To follow are sections describing the threat for flooding for
select river basins.


             ***************************************
             * Missouri River from Decatur to Rulo *
             ***************************************

Overview: As of February 19, the river continues to run above
normal, largely due to the slightly above-normal releases from
Gavins Point Dam. While this doesn`t translate directly to increased
flood potential, starting at a higher point than normal does tilt
the odds that direction. With around 30% of the mountain snowpack
still to fall, a lot can change relative to the Missouri
River flood potential. Mountain snowpack in the headwaters of the
Missouri River,as of February 18th, is 92% of average. At this
point, it is safe to say locations along the Missouri River, below
the Platte River confluence, have a greater than normal chance for
at least reaching flood stage this spring.

                      Average                 Recent Streamflow
                    Streamflow    Long-term      as a % of
                   Past 14 Days   mean flow    long-term mean
--------------------------------------------------------------------
Missouri River:
  at Decatur          21,473       20,200         106%
  at Omaha            23,294       21,300         109%
  at Nebraska City    33,969       27,900         122%
  at Rulo             34,608       29,800         116%


                           ******************
                           * Niobrara River *
                           ******************

                           Chance of Reaching
                              Flood Stage           Chance of
                          Compared to Normal      Minor Flooding
--------------------------------------------------------------------
Niobrara River:
  at Verdel                  Near Normal             <5%

Ponca Creek:
  at Verdel                    7% Less                7%


                         ************************
                         * Big Blue River Basin *
                         ************************

                          Chance of Reaching
                             Flood Stage            Chance of
                          Compared to Normal      Minor Flooding
--------------------------------------------------------------------
Big Blue River:
  at Surprise                   1% Less                9%
  at Seward                     7% Greater            16%
  at Crete                      2% Less               26%
  at Beatrice                  14% Less                8%
  at Barneston                  4% Less                9%

Lincoln Creek:
  at Seward                     4% Greater            27%

W Fk Big Blue River:
  at Dorchester                 7% Less               15%

Turkey Creek:
  at Wilber                     5% Less               33%

Little Blue River
  at Deweese                    4% Less                9%
  at Fairbury                  Near Normal            <5%


                         ***********************
                         * Elkhorn River Basin *
                         ***********************

Overview: Some intact ice cover remains along the Elkhorn River,
though much of this ice is not thick enough to create ice jam
concerns. While the overall ice jam threat is low, a small ice jam
should not be ruled out until a substantial warm-up occurs.

                          Chance of Reaching
                             Flood Stage             Chance of
                          Compared to Normal      Minor Flooding
--------------------------------------------------------------------
Elkhorn River:
  at Neligh                   Near Normal             <5%
  at Norfolk                  Near Normal             <5%
  at Pilger                   Near Normal             <5%
  at West Point                1% Greater              6%
  at Winslow                  Near Normal             <5%
  at Waterloo                 Near Normal             <5%

N Fk Elkhorn River:
  at Pierce                    2% Less                 7%

Maple Creek:
  at Nickerson                 7% Less                 5%

Logan Creek:
  at Uehling                  Near Normal             <5%


                         **********************
                         * Platte River Basin *
                         **********************

Overview: For the lower Platte River, a small threat for ice jams
does remain. During the week of January 26th a majority of the
intact ice cover move through the Platte River system, largely
due to increased flows from the Loup River. This ice movement did
result in a fairly significant ice jam near the Two Rivers State
Park Recreation Area. On January 29th the ice jam released on its
own. In recent weeks another small ice jam formed in the same area,
however the effects were minor and it did not persist long. Due to
recent cold temperatures, the river remains full of frazil ice, also
known as slush ice. Until a substantial warm-up occurs, the possibly
for a minor ice jam remains. Mountain snowpack in the headwaters of
the Platte River is around 83% of average.

                           Chance of Reaching
                              Flood Stage           Chance of
                          Compared to Normal      Minor Flooding
--------------------------------------------------------------------
Platte River:
  at Duncan                     1% Less               <5%
  at North Bend                 7% Less                6%
  at Leshara                    8% Less                9%
  at Ashland                    8% Less               11%
  at Louisville                13% Less                7%

Shell Creek:
  at Columbus                 Near Normal              5%

Salt Creek:
  at Roca                     Near Normal              8%
  at Lincoln                    1% Less                8%
  at Greenwood                Near Normal             14%
  at Ashland                   5% Greater             35%

Wahoo Creek:
 at Ithaca                     7% Greater             42%


                *******************************************
                * Other tributaries to the Missouri River *
                *******************************************

                                 Chance of Reaching
                                     Flood Stage        Chance of
                                 Compared to Normal   Minor Flooding
--------------------------------------------------------------------
Maple River at Mapleton
Little Sioux River at Turin
Soldier River at Pisgah             Near Normal           <5%
Boyer River at Logan                 5% Greater           11%
Weeping Water Creek at Union         2% Less               9%

Nishnabotna River:
  East Nishnabotna at Red Oak        4% Less              24%
  West Nishnabotna at Hancock        8% Less              23%
  West Nishnabotna at Randolph       2% Less              24%
  Nishnabotna at Hamburg            16% Less              29%

Little Nemaha River at Auburn        2% Less              11%
N Fk Big Nemaha River at Humboldt   Near Normal           <5%
Big Nemaha River at Falls City       4% Less              <5%
Nodaway River at Clarinda           Near Normal           <5%

To follow are three tables which provide more detailed information
about the flooding threat this spring.

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.


...Table 1--Probabilities for minor...moderate and major flooding...
                    Valid Period:  2/21/2015 - 5/22/2015

                                       :    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
--------           -----  -----  ----- : ---  ---  ---  ---  ---  ---
:Niobrara River
Verdel               7.0    9.0   10.0 :  <5   <5   <5   <5   <5   <5
:Ponca Creek
Verdel              12.0   15.0   17.0 :   7   14   <5    7   <5   <5
:Elkhorn River
Neligh              11.0   12.0   14.0 :  <5   <5   <5   <5   <5   <5
Norfolk             12.0   13.0   17.0 :  <5   <5   <5   <5   <5   <5
:North Fork Elkhorn River
Pierce              12.0   14.0   16.0 :   7    9    6   <5    6   <5
:Elkhorn River
Pilger              12.0   14.0   15.0 :  <5   <5   <5   <5   <5   <5
West Point          12.0   16.0   18.7 :   6    5   <5   <5   <5   <5
Winslow             18.0   20.0   24.0 :  <5   <5   <5   <5   <5   <5
:Logan Creek
Uehling             18.0   19.0   21.0 :  <5   <5   <5   <5   <5   <5
:Maple Creek
Nickerson           11.5   13.0   17.0 :   5   12   <5    6   <5   <5
:Elkhorn River
Waterloo            17.0   18.0   21.0 :  <5   <5   <5   <5   <5   <5
:Platte River
Duncan               8.0    9.0   10.0 :  <5    6   <5   <5   <5   <5
:Shell Creek
Columbus            20.0   21.0   22.0 :   5    5   <5   <5   <5   <5
:Platte River
North Bend           8.0   12.0   15.0 :   6   13   <5   <5   <5   <5
Leshara              8.0   10.0   12.0 :   9   17   <5   <5   <5   <5
Ashland             20.0   22.0   26.0 :   8   19   <5   <5   <5   <5
:Salt Creek
Roca                19.0   23.0   26.0 :   8    8   <5   <5   <5   <5
Lincoln             20.5   26.5   33.0 :   8    9   <5   <5   <5   <5
Greenwood           20.0   24.0   27.0 :  14   14    7    7    5   <5
:Wahoo Creek
Ithaca              19.0   22.0   23.0 :  42   35   15    7   <5   <5
:Salt Creek
Ashland             16.0   20.0   23.0 :  35   30   <5   <5   <5   <5
:Platte River
Louisville           9.0   11.0   12.0 :   7   20   <5   <5   <5   <5
:Big Blue River
Surprise             7.0   10.0   12.0 :   9   10   <5   <5   <5   <5
:Lincoln Creek
Seward              15.0   17.0   20.0 :  27   23    8    8   <5   <5
:Big Blue River
Seward              18.0   22.0   27.0 :  16    9   <5   <5   <5   <5
:West Fork Big Blue River
Dorchester          15.0   22.0   24.4 :  15   22   <5   <5   <5   <5
:Big Blue River
Crete               21.0   25.0   29.0 :  26   28   <5    6   <5   <5
:Turkey Creek
Wilber              12.5   16.0   21.0 :  33   38   <5   <5   <5   <5
:Big Blue River
Beatrice            18.0   26.0   32.0 :   8   22   <5   <5   <5   <5
Barneston           20.0   27.0   34.0 :   9   13   <5    6   <5   <5
:Little Blue River
Fairbury            18.5   20.0   26.0 :  <5   <5   <5   <5   <5   <5
:Maple River
Mapleton            21.0   24.0   27.0 :  <5   <5   <5   <5   <5   <5
:Little Sioux River
Turin               25.0   28.0   34.5 :  12    7   <5   <5   <5   <5
:Soldier River
Pisgah              28.0   29.0   30.0 :  <5   <5   <5   <5   <5   <5
:Boyer River
Logan               19.0   22.0   25.0 :  11    6   <5   <5   <5   <5
:Weeping Water Creek
Union               25.0   28.0   30.0 :   9   11   <5   <5   <5   <5
:East Nishnabotna River
Red Oak             18.0   22.0   27.0 :  24   28    5    8   <5   <5
:West Nishnabotna River
Hancock             14.0   19.0   23.0 :  23   31   11   14   <5   <5
Randolph            19.0   22.0   24.0 :  24   26   11    6   <5   <5
:Nishnabotna River
Hamburg             25.0   27.0   33.0 :  29   45   13   19   <5   <5
:Little Nemaha River
Auburn              22.0   23.0   27.0 :  11   13    6   11   <5   <5
:North Fork Big Nemaha River
Humboldt            28.0   29.5   31.0 :  <5   <5   <5   <5   <5   <5
:Big Nemaha River
Falls City          27.0   33.0   36.0 :  <5    9   <5   <5   <5   <5
:Nodaway River
Clarinda            23.0   26.0   29.0 :  <5   <5   <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: 2/21/2015 - 5/22/2015
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Niobrara River
Verdel                3.1    3.1    3.2    3.4    3.7    4.1    4.5
:Ponca Creek
Verdel                4.5    4.7    5.2    6.5    8.1   11.0   12.8
:Elkhorn River
Neligh                1.9    2.5    3.7    4.9    5.8    6.5    7.4
Norfolk               2.4    2.5    2.9    3.8    4.5    5.2    8.1
:North Fork Elkhorn River
Pierce                2.7    2.9    3.5    5.0    8.2   10.9   17.2
:Elkhorn River
Pilger                7.2    7.5    8.0    8.6    9.1    9.8   11.6
West Point            6.6    7.0    7.6    8.4    9.3   10.8   12.3
Winslow               8.4    8.9    9.9   11.0   13.8   15.6   17.3
:Logan Creek
Uehling               2.8    3.2    4.6    6.9   10.4   13.7   15.4
:Maple Creek
Nickerson             5.1    5.6    6.2    7.4    8.4   10.5   11.8
:Elkhorn River
Waterloo              3.6    4.2    5.7    7.2   10.0   13.0   14.7
:Platte River
Duncan                4.2    4.2    4.2    4.6    5.5    6.2    7.7
:Shell Creek
Columbus              5.2    5.4    6.4   10.4   15.6   18.9   20.0
:Platte River
North Bend            4.7    4.9    5.2    6.0    6.7    7.4    8.1
Leshara               4.8    5.0    5.4    6.4    7.2    7.9    8.6
Ashland              17.3   17.4   17.6   18.3   19.0   19.8   20.2
:Salt Creek
Roca                  2.1    3.2    4.6    7.3   13.5   18.3   19.8
Lincoln               2.7    3.8    5.3   10.2   15.0   18.7   24.4
Greenwood             2.9    4.9    6.5   12.6   17.9   21.6   26.6
:Wahoo Creek
Ithaca                3.8    6.1   11.0   16.1   21.7   22.1   22.6
:Salt Creek
Ashland               7.0    8.8    9.7   13.5   17.4   18.4   19.6
:Platte River
Louisville            3.9    4.2    4.8    6.2    7.6    8.8    9.1
:Big Blue River
Surprise              1.3    1.3    2.8    3.2    4.8    6.9    9.1
:Lincoln Creek
Seward                3.9    3.9   10.1   12.2   15.3   16.4   17.8
:Big Blue River
Seward                1.5    2.1    7.0   11.1   15.7   18.3   20.1
:West Fork Big Blue River
Dorchester            2.8    2.8    6.7   10.3   13.4   16.6   18.8
:Big Blue River
Crete                 6.9    7.5   12.6   16.6   21.2   23.3   24.7
:Turkey Creek
Wilber                1.4    3.1    7.2   10.6   12.8   14.7   15.6
:Big Blue River
Beatrice              4.0    5.1    8.1   10.9   15.5   17.4   18.5
Barneston             5.5    6.6    9.3   12.8   16.3   19.6   24.3
:Little Blue River
Fairbury              8.3    8.6   10.7   12.6   15.3   16.2   17.4
:Maple River
Mapleton              7.8    8.5    9.9   12.8   15.3   19.1   20.1
:Little Sioux River
Turin                 9.6   10.7   11.9   16.7   18.4   25.8   26.3
:Soldier River
Pisgah                4.8    5.6    6.5    7.9    9.7   11.4   12.1
:Boyer River
Logan                 6.8    7.4    8.5    9.8   14.2   20.2   21.5
:Weeping Water Creek
Union                 2.6    3.7    6.9    8.7   17.1   24.3   26.0
:East Nishnabotna River
Red Oak               7.0    8.6   10.7   14.1   17.7   21.4   22.0
:West Nishnabotna River
Hancock               4.3    5.4    7.4    9.0   12.2   19.7   22.0
Randolph              9.0   10.5   12.9   15.8   18.7   22.2   23.0
:Nishnabotna River
Hamburg              10.1   12.8   16.8   21.4   25.1   27.5   28.5
:Little Nemaha River
Auburn                3.8    6.7    9.4   12.4   18.3   22.7   23.0
:North Fork Big Nemaha River
Humboldt              4.4    5.3    7.2    9.0   12.3   15.4   16.9
:Big Nemaha River
Falls City            6.2    8.1   10.5   14.2   18.4   22.6   26.4
:Nodaway River
Clarinda             10.8   12.0   12.6   13.9   17.3   21.4   21.7

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: 2/21/2015 - 5/22/2015
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Niobrara River
Verdel                3.0    3.0    3.0    3.0    2.9    2.9    2.9
:Ponca Creek
Verdel                4.3    4.3    4.2    4.2    4.1    3.5    3.5
:Elkhorn River
Neligh                1.9    1.9    1.4    0.8    0.6    0.6    0.6
Norfolk               2.2    2.2    2.1    2.0    1.9    1.8    1.8
:North Fork Elkhorn River
Pierce                2.7    2.7    2.6    2.5    2.3    2.2    2.1
:Elkhorn River
Pilger                7.1    7.0    7.0    6.7    6.5    6.4    6.3
West Point            6.3    6.2    6.2    5.9    5.6    5.4    5.3
Winslow               7.7    7.7    7.7    7.3    6.9    6.7    6.7
:Logan Creek
Uehling               2.6    2.6    2.4    2.3    2.2    2.1    2.1
:Maple Creek
Nickerson             1.0    1.0    1.0    1.0    1.0    1.0    1.0
:Elkhorn River
Waterloo              2.4    2.4    2.4    2.1    1.8    1.7    1.5
:Platte River
Duncan                3.9    3.8    3.5    3.2    3.1    3.0    3.0
:Shell Creek
Columbus              0.6    0.6    0.6    0.6    0.6    0.6    0.6
:Platte River
North Bend            3.8    3.6    3.3    3.1    2.8    2.7    2.6
Leshara               4.3    4.2    4.1    3.8    3.5    3.4    3.3
Ashland              17.0   17.0   16.8   16.7   16.6   16.5   16.5
:Salt Creek
Roca                  1.6    1.6    1.6    1.6    1.6    1.6    1.6
Lincoln               2.5    2.5    2.5    2.5    2.5    2.5    2.5
Greenwood             2.6    2.6    2.6    2.6    2.6    2.6    2.6
:Wahoo Creek
Ithaca                3.7    3.7    3.7    3.7    3.7    3.7    3.6
:Salt Creek
Ashland               6.6    6.6    6.6    6.5    6.5    6.4    6.4
:Platte River
Louisville            3.2    3.1    3.0    2.4    2.0    1.6    1.3
:Big Blue River
Surprise              1.1    1.1    1.1    1.1    1.0    1.0    1.0
:Lincoln Creek
Seward                3.9    3.9    3.9    3.9    3.9    3.8    3.7
:Big Blue River
Seward                1.5    1.5    1.5    1.4    1.3    1.3    1.3
:West Fork Big Blue River
Dorchester            2.8    2.8    2.8    2.8    2.7    2.6    2.6
:Big Blue River
Crete                 6.9    6.9    6.9    6.9    6.8    6.7    6.7
:Turkey Creek
Wilber                1.4    1.3    1.3    1.0    0.7    0.4    0.3
:Big Blue River
Beatrice              3.2    3.2    3.2    3.2    3.1    3.1    3.1
Barneston             3.4    3.4    3.4    3.4    3.3    3.2    3.2
:Little Blue River
Fairbury              7.7    7.7    7.7    7.7    7.6    7.5    7.5
:Maple River
Mapleton              5.3    5.3    5.3    5.3    5.3    5.2    5.2
:Little Sioux River
Turin                 7.5    7.5    7.4    7.4    7.3    7.3    7.2
:Soldier River
Pisgah                3.2    3.2    3.2    3.2    3.2    3.1    3.1
:Boyer River
Logan                 3.3    3.3    3.3    3.3    3.2    3.2    3.2
:Weeping Water Creek
Union                 2.0    2.0    2.0    2.0    2.0    2.0    2.0
:East Nishnabotna River
Red Oak               5.9    5.9    5.9    5.8    5.7    5.7    5.6
:West Nishnabotna River
Hancock               2.0    2.0    2.0    2.0    1.9    1.9    1.8
Randolph              7.8    7.8    7.8    7.7    7.3    7.1    6.9
:Nishnabotna River
Hamburg               8.6    8.6    8.5    8.4    8.1    7.7    7.6
:Little Nemaha River
Auburn                2.6    2.6    2.6    2.6    2.2    1.8    1.8
:North Fork Big Nemaha River
Humboldt              2.0    2.0    2.0    2.0    2.0    2.0    2.0
:Big Nemaha River
Falls City            3.8    3.8    3.8    3.7    3.6    3.5    3.5
:Nodaway River
Clarinda             10.6   10.6   10.6   10.6   10.5   10.5   10.5

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/oax for more weather and water
information.

Question regarding this outlook should be directed to:

David Pearson
National Weather Service Omaha
Senior Service Hydrologist
david.pearson@noaa.gov
402-359-5732

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