Flood Potential Outlook
Issued by NWS Great Falls, MT

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MTZALL-171800-

WATER SUPPLY AND FLOOD OUTLOOK
NATIONAL WEATHER SERVICE GREAT FALLS MT
330 PM MST THU FEB 16 2017

...Spring Flood and Water Resources Outlook...

...The potential for spring flooding for Montana east of the
Continental Divide during spring of 2017 is near or below normal...

This report is based upon conditions as of February 15, 2017.

OVERVIEW...
Mountain snowpack and snow water equivalent (SWE) is slightly
below normal in most basins. Exceptions include the Sun,
Teton and Marias Basin and the Upper Yellowstone Basin both of which
are well above the seasonal normal. At the other end of the spectrum,
the Smith, Judith, and Musselshell Basin is well below normal in terms
of SWE. At this point 30% of our snow accumulation period remains so
there is reason to believe that mountain snowpack will continue to
increase into spring.

Some snowpack remains over the eastern plains, but is otherwise non-
existent. Soil remains near or below freezing statewide, so moisture
will not yet permeate the ground.

CHANCES FOR MAJOR, MODERATE, or MINOR FLOODING...
Based on the current mountain snowpack, there is little threat  from
significant flooding on rivers east of the Continental Divide. However,
minor flooding is possible along tributaries of the Milk and
Yellowstone Rivers where higher SWE values are found.

CURRENT RIVER CONDITIONS...
With recent warm temperatures, many Montana streams and rivers have
opened. Streamflows west of the Continental Divide are generally near
or slightly above their long term median. East of the divide most
streamflows are mainly near normal with some above normal readings on
tributaries of the Yellowstone River in southern Montana.

Current streamflow forecasts anticipate near normal to slightly below
normal flows for the upcoming runoff season for Montana east and west
of the Continental Divide.

CURRENT SOIL CONDITIONS...
Soils are generally wetter than normal across Montana east of the
Continental Divide. Soils are also mostly unfrozen across western and
central Montana.

SOIL TEMPERATURE AND MOISTURE OBSERVATIONS FROM ACROSS MONTANA
SOIL TEMPERATURE IS IN DEGREES FAHRENHEIT.
Data as of February 15, 2017

SOIL TEMPERATURE /F/ AT LISTED DEPTH
              ELEV   2IN   4IN  6IN  8IN  12IN  20IN  30IN  40IN
Alberton NR   6150          33        34          35          36
Bozeman ExpSt 4774    30    31        30          32
Bozeman 12SE  6860                    33          34          35
Brusett 4SE   2643    31    30        30          31          29
Cameron 15SW  8800          32        32          32          34
Cooke City NR 8700          31        31          32           M
Conrad Scan   3706    32    31        32          30          34
Flattop Mtn   6300                    32
Great Falls   3776          32        33          33          34
Havre Scan    2710    32    32        32          33          34
Jordan Scan   2820    31    32        31          32           M
Lakeview Nr   7400          32        32          28          34
Lakeview 15nw 7800          32        33          34          35
Lincoln 11se  7020          32        32          34
Lindsay Scan  2680    32    32        32          33          35
Lookout Pass  5140           M        34          35           M
Many Glacier  4900                    34
Maxville NR   7210          33        34          34          35
Moccasin Scan 4256    32    32        32          33          35
Mt Lockhart   6400          33        32          33          34
Neihart 12SE  8100          31        31          32          33
Poplar 13NE   2085    29    30        29          29          33
Three Fks Scn 4775    32    32        31          33          36
Tiber Dam Scn 3225    27    29        29          28          31
Utica 11sw    5070    31    30        30          31          31
W Yellowst So 8150          33        32          34          35
White SS 13SE 7600          31        31          32          33

GROUND TEMPERATURE /F/ AT THE SURFACE AND 18 INCHES DEEP AT MT DOT
SITES

Aberdeen Hill 4101    30                      32
Alzada DOT    4327    27                      32
Arrow Creek   3956    26                      34
Avon North    5085    18                      18
Bearsmouth    3901    20                      32
Beaver Hill   2551    31                      32
Biddle DOT    3418    27                      32
Big Hole Pass 7400    23                      20
Boulder Pass  5600    26                      32
Bowmans Cornr 4301    35                      31
Bozeman Pass  5748    23                      33
Bull Mountain 3898    29                      32
Comerstown    2099    30                      40
Cow Creek     2500    29                      31
Crystal Creek 3030    19                      29
Deep Creek    5870    20                      30
Dearborn      3500    38                      31
Denton DOT    3557    28                      31
E Livingston  4555    37                      37
Ekalaka DOT   3687    29                      30
Essex DOT     3875    19                      27
Garrison DOT  4327    20                      31
Georgetown Lk 6339    15                      28
Geyser DOT    4138    39                      32
Government Hl 3165    28                      32
Greenough Hl  4070    20                      30
Hays DOT      3697    28                      30
Helmville DOT 4199    17                      31
Hillside DOT  2998    29                      32
Hysham Hills  3549    32                      32
Ingomar DOT   3018    24                      30
Inverness     3300    27                       M
Judith Gap    4677    27                      32
Karst DOT     5698    25                      30
Lame Deer     4327     M                       M
Lewistown Dvd 4622    30                      27
Lindsay Div   3198     M                       M
Loma DOT      2557    28                      31
Lookout Pass  4540    23                      30
Macdonald Pss 6320    23                      29
Malta South   3122    32                      31
Mcdonalds DOT 2401    28                      29
Monarch Canyn 5218    32                      31
Monida Pass   6824    19                      29
Navaho DOT    2570    26                      29
Ninemile DOT  4301    19                      27
Norris Hill   5695    29                      31
Pendroy DOT   4199    26                      31
Raynolds Pass 6778    19                      30
Reedpoint DOT 3890    21                      32
Rogers Pass   5406    31                      31
Roscoe Hill   5337    28                      31
Saco DOT      2177    26                      34
Sieben DOT    4040    25                      31
Sioux Pass    2480    29                      30
Swan Lake     3567    22                      30
Sweeney Creek 2598    28                      33
Sweet Grass   3690    37                      31
Trout Creek   2384    21                      31
Two Medicine  4920    39                      30
US2 Stateline 2099    29                      28
Yaak Hill     2201    24                      31
Yellowstone B 3194    32                      34

FROST...DEPTH OF SURFACE THAWED / DEPTH OF FROST PENETRATION...INCHES
WHEN FROST PENETRATION VALUES ARE LARGE, THESE VALUES MAY BE
OVERESTIMATED BY A FOOT OR MORE.

Glasgow                0    44
Great Falls            5    18

SOIL MOISTURE /VOLUMETRIC SOIL MOISTURE IN PERCENT/ AT LISTED DEPTH
SOIL MOISTURE IS IN UNITS OF PERCENT VOLUMETRIC SOIL MOISTURE.
VALUES AT OR NEAR ZERO MAY BE ERRONEOUS.
               ELEV   2IN   4IN  6IN  8IN  12IN  20IN  30IN  40IN
Alberton NR   6150          22       30          10          13
Bozeman 12SE  6860                   16          40          33
Brusett 4SE   2643     9    10        7           4           7
Cameron 15SW  8800           M       35          38          41
Conrad Scan   3706    20    22       21          24          36
Cooke City NR 8700           8        0           5           M
Flattop Mtn   6300                   24
Havre Scan    2710    13    16       24          27          23
Jordan Scan   2820    16    20       24          23          14
Lakeview Near 7400           8        8          34          26
Lakeview 15NW 7800          25       14          28          23
Lincoln 11SE  7020          18       18          17           M
Lindsay Scan  2860     8     8        9           5          10
Lookout Pass  5140           M       39          35
Many Glacier  4900                    9
Maxville NR   7210           0        0           0           7
Moccasin Scan 4256    18    19       22          15           8
Mt Lockhart   6400          33       34          33
Neihart 12SE  8100          20       22          28          32
Three Fks Scn 4775    16    20       28          37           8
Tiber Dam Scn 3225    11    18       23           7           4
Utica 11SW    5070     7    11        8          10           7
W Yellowst So 8150          22       23          26          31
White SS 13SE 7600           1        2           3          23


CURRENT SNOW CONDITIONS...
As of February 15, for individual basins, the Natural Resources
Conservation Service, NRCS, is reporting conditions in Montana
ranging from above to below normal.

Montana Watershed Current Snow Water Equivalent percent of Normal`
Watershed                       SWE
Bitterroot                      99%
Flathead                        96%
Gallatin                        90%
Headwaters Upper Missouri       94%
Headwaters Mainstem Missouri    91%
Jefferson                       93%
Kootenai                        94%
Lower Clark Fork                93%
Madison                        100%
St. Marys Milk                105%
Sun-Teton-Marias               119%
Smith-Judith-Musselshell        68%
Upper Clark Fork                90%
Upper Yellowstone              127%

Below are conditions as of February 15, for select individual SNOTEL
sites for basins in Montana. The information provided for each site
includes site elevation...current snow water equivalent, median SWE
for the date, median peak SWE, average date of the median peak SWE,
current SWE as a percent of median, current SWE as a percent of the
median peak, current snow depth and the current snow density.
Additionally, a basin-wide percent of average SWE is provided. This
is an abbreviated list...only those sites with the maximum...nearest
to median...and the minimum percent SWE for each basin are provided.
The list is sorted by major river basin.

SNOTEL SITE       ELEV CURR   MED   MED  MED PK  PCT  PCT SNOW  SNOW
                        SWE   SWE  PEAK   DATE   MED PEAK DPTH DENSITY
Kootenai River Basin
 Garver Creek     4250  7.7   7.1   9.2  Mar 28  110   84   40    19
 Grave Creek      4300 11.6  11.8  14.6  Mar 26   99   79   48    24
 Hawkins Lake     6450 19.2  17.1  26.0  May 03  112   73   74    26
 Stahl Peak       6030 28.8  24.3  36.7  May 07  120   78   94    31
Basin Index (%)                                   94   70

Flathead River Basin
 Bisson Creek     4920  6.0   7.1  10.0  Apr 05   87   61   22    27
 Flattop Mtn.     6300 30.4  30.5  43.4  Apr 13  100   70  101    30
 Many Glacier     4900 12.8  10.2  12.6  Mar 30  125  102   47    27
Basin Index (%)                                   97   71

Upper Clark Fork River Basin
 Basin Creek      7180  3.6   5.0   9.0  May 05   73   40   17    21
 North Fork Jocko 6330 21.3  29.9  42.5  Apr 11   72   50   68    31
 Rocker Peak      8000  8.0   9.0  15.3  May 10   89   52   35    23
Basin Index (%)                                   91   66

Bitterroot River Basin
 Daly Creek       5780  8.2   7.3   9.7  Mar 29  114   85   32    26
 Skalkaho Summit  7250 14.3  15.1  22.2  Apr 10   95   64   56    26
 Twin Lakes       6400 24.9  26.9  35.7  Apr 04   94   70   76    33
Basin Index (%)                                  100   76

Lower Clark Fork River Basin
 Hoodoo Basin     6050 26.4  27.5  40.1  Apr 18   96   66    86   31
 Humboldt Gulch   4250  9.4   8.8  10.1  Feb 23  107   93    29   32
 Lolo Pass        5240 20.6  19.5  27.1  Apr 01  105   75    62   33
Basin Index (%)                                   94   71

Jefferson River Basin
 Clover Meadow    8600  7.7  10.8  17.6  Apr 25   72   44    33   23
 Darkhorse Lake   8600 21.6  19.5  31.2  May 11  112   69    73   30
 Short Creek      7000  3.2   3.9   5.8  Apr 09   84   55    18   18
Basin Index (%)                                   94   61

Madison River Basin
 Black Bear       8170 29.4  26.9   37.4 Apr 30  110   79    91   32
 Lone Mountain    8880 11.0  12.0   18.9 May 11   92   58    42   26
 Tepee Creek      8000  7.7   9.3   13.4 May 01   84   57    32   24
Basin Index (%)                                  100   66

Gallatin River Basin
 Carrot Basin     9000 19.1  18.1   28.9 May 07  106   66    74   26
 Lick Creek       6860  5.2   6.9   11.5 Apr 05   76   45    22   24
 Shower Falls     8100 11.3  13.7   25.7 May 15   84   44    45   25
Basin Index (%)                                   91   55

Missouri Headwaters
 Black Bear       8170 29.4  26.9   37.4 Apr 30  110   79    91   32
 Lower Twin       7900  9.8  11.8   19.3 May 15   84   51    40   25
 Short Creek      7000  3.2   3.9    5.8 Apr 09   84   55    18   18
Basin Index (%)                                   96   63

Headwaters Missouri Mainstem
 Frohner Meadow   6480  6.4   5.2    7.6 Apr 11  125   84    27   24
 Nevada Ridge     7020 11.0   9.6   14.3 Apr 06  116   77    42   26
 Rocker Peak      8000  8.0   9.0   15.3 May 10   89   52    35   23
Basin Index (%)                                   94   65

Smith, Judith, and Musselshell River Basins
 Crystal Lake     6050  4.9   8.4   13.2 Apr 13   58   37    19   26
 Porcupine        6500  3.3   4.6    6.0 Apr 09   72   55    14   24
 Spur Park        8100 10.8  13.9   22.7 May 04   78   47    42   26
Basin Index (%)                                   68   46

Sun, Teton, and Marias River Basins
 Badger Pass      6900 22.6  20.9   31.3 Apr 13  108   72    73   31
 Waldron          5600 10.2   7.2   10.8 Apr 05  142   94    42   24
 Wood Creek       5960  6.9   6.5    8.6 Apr 11  108   80    26   27
Basin Index (%)                                  120   84

Missouri Mainstem River Basin
 Badger Pass      6900 22.6  20.9   31.3 Apr 13  108   72    73   31
 Porcupine        6500  3.3   4.6    6.0 Apr 09   72   55    14   24
 Wood Creek       5960  6.9   6.5    8.6 Apr 11  108   80    26   27
Basin Index (%)                                   92   63

St mary and Milk River Basin
 Flattop Mtn.     6300 30.4  30.5   43.4 Apr 13  100   70   101   30
 Many Glacier     4900 12.8  10.2   12.6 Mar 30  125  102    47   27
 Rocky Boy        4700  3.4   3.6    4.4 Mar 12   94   77     8   43
Basin Index (%)                                  105   83

Upper Yellowstone River Basin
 Fisher Creek     9100 29.2  22.7   34.4 May 12  130   85   105   28
 Porcupine        6500  3.3   4.6    6.0 Apr 09   72   55    14   24
 Sylvan Road      7120 13.2   8.6   11.1 Apr 02  155  119    48   28
Basin Index (%)                                  127   82

Lower Yellowstone River Basin
 Bear Trap Meadow 8200  3.8   3.7    5.2 Mar 24  103   73    21   18
 Cold Springs     9630  9.2   4.9    7.1 Apr 01  188  130    40   23
 Evening Star     9200 27.6  17.1   25.6 May 12  161  108   100   28
Basin Index (%)                                  144   87


This outlook contains a generalized summary of snowmelt flood potential.
Above normal future snow accumulations combined with heavy rains and
rapid melt will increase the current flood potential. Below normal
future precipitation and gradual or intermittent freezing and thawing
will decrease the magnitude of the current assessment. Additionally,
when the remaining frozen rivers and streams thaw, ice jams may develop
causing higher river levels and possible flooding. Ice jam flooding will
continue to be a threat for some locations through April.

Projections of river stages are based on current observed states of
streamflow, soil moisture, and snow pack, coupled with future
precipitation and temperature patterns and anticipated operational
hydrologic changes such as reservoir releases and canal diversions.
Outlooks are provided for long-range projections...weeks to months...
based on climatological patterns of precipitation and temperature.
Forecasts are provided for short-term projections...days...based on
future forecasted patterns of precipitation and temperature. The
uncertainty of these products varies from season to season and site
to site. In recent years, outlook crests have been above the observed
crest about as often as they have been below the observed crest. The
uncertainty of forecasts tends to be less than the uncertainty of
outlooks due to their shorter lead time. Users of these products are
encouraged to contact their nearest National Weather Service Forecast
Office for continued updates of meteorological conditions which can
have significant impacts on flood planning and flood fighting activities.

Outlook numbers for locations not represented in NWS AHPS products are
not being issued with this product. For additional quantitative
information, please refer to AHPS products for probabilistic forecasts
of potential flooding. Refer to flood forecasts, if any are currently
issued, for information about ongoing or anticipated flooding.

$$

.END/BRITTON


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