Flood Potential Outlook
Issued by NWS Great Falls, MT

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HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE GREAT FALLS MT
434 PM MST THU FEB 19 2015

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

This outlook is for the rivers of Montana east of the Continental Divide.

...The potential for spring flooding for Montana east of the Continental Divide during spring of 2015 is near to below normal...

Overall, mountain snowpack is near average. Snowpack over the plains is shallow. Frozen ground conditions are primarily limited to northeast and eastern Montana. Precipitation during the summer and fall of 2014 have provided for moist antecedent soil conditions. With a near average snowpack, and generally open, albeit moist, soils, the chance of widespread significant flooding either in the mountainous areas or on the plains is unlikely.

Some minor ice jam flooding has already occurred. Ice jam flooding is possible over the next 4 to 8 weeks as spring break-up occurs.

CHANCES FOR MAJOR FLOODING
Based on the snowpack as of February 19 in the mountains of Montana and the snow cover over the plains...
* A 10 to 15 percent chance of major flooding on the Shields River near Livingston.
* All other sites east of the Continental Divide have a less than 10 percent chance of minor flooding due to snowmelt.

CHANCES FOR MODERATE FLOODING
Based on the current snowpack in the mountains of Montana and the current snow cover over the plains, outlooks show...
* A 15 to 20 percent chance of moderate flooding on the Shields River near Livingston
* All other sites east of the Continental Divide have a less than 10 percent chance of minor flooding due to snowmelt.

CHANCES FOR MINOR FLOODING
Based on the current snowpack in the mountains of Montana and the current snow cover over the plains, outlooks show...
* A 10 to 15 percent chance of minor flooding on Gallatin River near Logan
* A 10 to 15 percent chance of minor flooding on Beaver Creek near Hinsdale
* A 20 to 25 percent chance of minor flooding on the Shields River near Livingston.
* A 35 to 40 percent chance of minor flooding on the Clarks Fork of the Yellowstone near Belfry.
* A 35 to 40 percent chance of minor flooding on the Clarks Fork of the Yellowstone near Edgar.
* All other sites east of the Continental Divide have a less than 10 percent chance of minor flooding due to snowmelt.

CURRENT RIVER CONDITIONS...
With recent warm temperatures, many Montana streams and rivers east of the Continental Divide have opened though some, particularly in northern and eastern Montana, are still in ice. Of those rivers that are open, most currently have flows near to well above their long term median.

CURRENT SOIL CONDITIONS...
Soils are wetter than normal across Montana east of the Continental Divide. Frost depth reports indicate soil is mostly unfrozen across western and central Montana. In eastern Montana frost depth ranges from a few inches to over 2 feet in depth.

SOIL TEMPERATURE /DEGREES F/ AT LISTED DEPTH
                2IN   4IN  6IN  8IN  12IN  20IN  25IN  30IN  40IN
 ALBERTON              33        34          35               36
 BOZEMAN EXP STN 34    34        33          35
 BOZEMAN 12SE                    34          34               35
 CAMERON 15SW          32        32          33               34
 COOKE CITY            32        32          33                M
 CONRAD SCAN     33    34        33          32               36
 FLATTOP MOUNTAIN                34
 GREAT FALLS     37    38        38          39
 HAVRE SCAN      33    33        33          35               37
 HELENA                41        40
 JORDAN SCAN     31    32        32          32                M
 LAKEVIEW              32        32          28               34
 LAKEVIEW 15NW         32        33          34               36
 LINCOLN 11SE          32        33          35
 LINDSAY SCAN    28    29        31          34               35
 LOOKOUT PASS           M        34          34                M
 MANY GLACIER                    34
 MAXVILLE              33        34          35               36
 MOCCASIN SCAN   33    34        36          37               38
 MOSBY 19NNE                      M
 MOUNT LOCKHART        33        33          34               34
 NEIHART 12SE          32        32          33               33
 SIDNEY 6NW      25              27
 SIDNEY 8SW      24              26
 SIDNEY SCAN     23    23        25          30                M
 THREE FRKS SCAN 36    37        38          38               39
 TIBER DAM SCAN  32    32        32          34               36
 WEST YELLOWSTONE      33        32          33               35
 WEST YELLOWST S       33        32          34               35
 WHT SULPHUR 13SE      32        32          32               34


GROUND TEMPERATURE /DEGREES F/ AT THE SURFACE AND 18 INCHES DEEP AT MONTANA DEPARTMENT OF TRANSPORTATION SITES

               SURFACE                  18IN
 ABERDEEN HILL   28                      35
 ALZADA DOT      23                      32
 ARROW CREEK     72                      39
 AVON NORTH      26                      26
 BEARSMOUTH DOT  29                      39
 BEAVER HILL     24                      25
 BIDDLE DOT      22                      29
 BIG HOLE PASS   21                      21
 BOULDER PASS    28                      36
 BOWMANS CORNER  33                      39
 BOZEMAN PASS    31                      42
 BULL MOUNTAIN   31                      37
 COMERSTOWN      16                      18
 COW CREEK       25                      27
 CRYSTAL CREEK   26                      35
 DEARBORN        44                      44
 DENTON DOT      29                      35
 EAST LIVINSTON  39                      46
 EKALAKA DOT     22                      32
 ESSEX DOT       26                      21
 GARRISON DOT    26                      37
 GEORGETOWN LAK  23                      32
 GEYSER DOT      35                      37
 GOVERNMENT HIL  25                      32
 GREENOUGH HILL  25                      34
 HAYS DOT        41                      32
 HELMVILLE DOT   26                      37
 HILLSIDE DOT    23                      31
 HYSHAM HILLS    29                      37
 INGOMAR DOT     23                      33
 INVERNESS       29                       M
 JUDITH GAP      31                      36
 KARST DOT       28                      35
 LAME DEER       25                      32
 LEWISTOWN DVD   27                      31
 LINDSAY DIVIDE  22                      28
 LOMA DOT        27                      36
 MACDONALD PASS  27                      32
 MCDONALDS DOT   21                      21
 MONARCH CANYON  22                      31
 MONIDA PASS     34                      36
 NAVAHO DOT      18                      20
 NINEMILE DOT    28                      33
 NORRIS HILL     31                      33
 PENDROY DOT     29                      32
 RAYNOLDS PASS   23                      32
 REEDPOINT DOT   39                      41
 ROGERS PASS     31                      35
 ROSCOE HILL     38                      25
 SACO DOT        21                      35
 SIEBEN DOT      36                      27
 SIOUX PASS      20                      30
 SWAN LAKE       26                      32
 SWEENEY CREEK   25                      33
 SWEET GRASS     30                      33
 TROUT CREEK     31                      37
 TWO MEDICINE    31                      32
 US2 STATELINE   19                      21
 YAAK HILL       27                      27
 YELLOWSTONE B   28                      40


SOIL MOISTURE /VOLUMETRIC SOIL MOISTURE IN PERCENT/ AT LISTED DEPTH
Soil moisture is in units of percent volumetric soil moisture. Field capacity of silt loam and clay loam soils is approximately 35 percent of volumetric soil moisture. Values at or near zero may be erroneous.

                2IN   4IN  6IN  8IN  12IN  20IN  25IN  30IN  40IN
 ALBERTON NR           22       30           8                13
 BOZEMAN 12SE                   20          41                46
 CAMERON 15SW          16       39          39                41
 CONRAD SCAN     32    32       29          35                37
 COOKE CITY NR         16        0           8                 M
 FLATTOP MOUNTAIN               36
 HAVRE SCAN      26    29       32          24                26
 JORDAN SCAN     16    20       24          26                15
 LAKEVIEW NEAR         10       13          34                26
 LAKEVIEW 18NW         30       18          27                16
 LINCOLN 11SE          22       22          18                 9
 LINDSAY SCAN     8     6       10          11                12
 LOOKOUT PASS           M       39          34
 MANY GLACIER                   11
 MAXVILLE NR           13        7           0                14
 MOCCASIN SCAN   27    29       30          21                12
 MOUNT LOCKHART        37       36          34
 NEIHART 12SE          30       32          29                33
 SIDNEY SCAN      9    10       16          15                 M
 THREE FKS SCAN  19    29       36          39                 7
 TIBER DAM SCAN  38    34       34           5                 4
 WEST YELLOWSTO        18        5           4                 0
 WEST YELLOW S         20       22          24                30
 WHITE SULPH 13SE       2        5          11                24


CURRENT SNOW CONDITIONS...
As of February 19, for individual basins, the Natural Resources Conservation Service, NRCS, is reporting conditions in Montana ranging from near to below normal. More than half the major watersheds, including Flathead, Upper Clark Fork, Bitterroot, Jefferson, Gallatin, Missouri Mainstem, Smith/Judith/Musselshell, and Upper Yellowstone, are reporting 100 to 112 percent of median. The Lower Clark Fork, Madison, and Sun/Teton/Marias are between 70 and 90 percent of normal. The Kootenai is at 67 percent of normal. Snow depths throughout the eastern plains of Montana range from 0 to 2 inches with the exception of the northeast corner of the state where isolated areas have snow up to 12 inches deep. Snow water equivalents, SWE, generally vary from 0 to 1.5 inches with isolated areas of northeast Montana having a SWE of 2 to 4 inches. Far southeast Alberta and southern Saskatchewan show conditions similar to northeast Montana. By late February,Montana is approximately three-quarters of the way through the main snow
fall period. There are still six to eight weeks remaining until the seasonal snowpack peak is reached.

Below are conditions as of February 19 2014 for some 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 percent SWE...the median percent SWE 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
  Poorman Creek  5100  14.3  27.1  36.2   6-Apr   53   40   39     37
  Hand Creek     5035   5.6   8.6  11.1  31-Mar   65   50   14     41
  Garver Creek   4250   5.3   7.6   9.2  28-Mar   70   58   17     31
  Stahl Peak     6030  23.5  25.3  36.7   7-May   93   64   64     37
Basin Index                                       67   50

FLATHEAD RIVER BASIN
  Many Glacier   4900   3.6  10.7  12.6  30-Mar   34   29   12     30
  Bisson Creek   4920   7.2   7.5  10.0   5-Apr   96   72   22     33
  Emery Creek    4350  10.9  11.3  13.7  31-Mar   96   80   30     36
  Moss Peak      6780  33.1  25.7  39.1  11-May  129   85   89     37
Basin Index                                      100   73

UPPER CLARK FORK RIVER BASIN
  Combination    5600   2.0   3.7   4.5  25-Mar   54   44    6     33
  Rocker Peak    8000  10.8   9.4  15.3  10-May  115   71   37     29
  Stuart Mtn     7400  27.4  23.8  31.2   7-Apr  115   88   76     36
  Peterson Mdws  7200   8.5  6.5   10.9  26-Apr  131   78   29     29
Basin Index                                      112   78

BITTERROOT RIVER BASIN
  Twelvemile Ck  5600  10.8  13.2  14.9  17-Mar   82   72   30     36
  Nez Perce Cp   5650  10.7   9.9  13.1   4-Apr  108   82   37     29
  Skalkaho Smt   7250  17.1  15.8  22.2  10-Apr  108   77   51     34
  Saddle Mtn     7940  21.4  17.8  24.0  17-Apr  120   89   65     33
Basin Index                                      102   79

LOWER CLARK FORK RIVER BASIN
  Lookout        5140   9.2  22.7  26.6  27-Mar   41   35   26     35
  Hoodoo Basin   6050  23.8  29.5  40.1  18-Apr   81   59   69     34
  Stuart Mtn     7400  27.4  23.8  31.2   7-Apr  115   88   76     36
Basin Index                                       73   57

JEFFERSON RIVER BASIN
  Lakeview Rdg   7400   4.1   7.6  10.8  10-Apr   54   38   17     24
  Frohner Mdw    6480   5.8   5.4   7.6  11-Apr  107   76   17     34
  Darkhorse Lk   8600  25.5  20.6  31.2  11-May  124   82   73     35
Basin Index                                      100   68

MADISON RIVER BASIN
  Lower Twin     7900   7.9  12.3  19.3  15-May   64   41   40     20
  Albro Lake     8300  11.2  12.9  20.0  23-Apr   87   56   39     29
  West Yellowstn 6700   7.3   8.0  10.2   1-Apr   91   72   26     28
Basin Index                                       84   58

GALLATIN RIVER BASIN
  Carrot Basin   9000  16.6  18.8  28.9   7-May   88   57   56     30
  Lone Mountain  8880  10.7  12.2  18.9  11-May   88   57   36     30
  Lick Creek     6860   7.1   7.4  11.5   5-Apr   96   62   23     31
  Brackett Creek 7320  19.4  13.4  20.8  15-Apr  145   93   57     34
Basin Index                                      103   67

MISSOURI HEADWATERS
  Lakeview Ridge 7400   4.1   7.6  10.8  10-Apr   54   38   17     24
  Lick Creek     6860   7.1   7.4  11.5   5-Apr   96   62   23     31
  Brackett Creek 7320  19.4  13.4  20.8  15-Apr  145   93   57     34
Basin Index                                       98   67

HEADWATERS MISSOURI MAINSTEM
  Tizer Basin    6880   5.7   6.8   9.9  10-Apr   84   58   21     27
  Frohner Meadow 6480   5.8   5.4   7.6  11-Apr  107   76   17     34
  Nevada Ridge   7020  12.4  10.1  14.3   6-Apr  123   87   38     33
Basin Index                                      105   71

SMITH, JUDITH, AND MUSSELSHELL RIVER BASINS
  Porcupine      6500   2.8   4.8   6.0   9-Apr   58   47    8     34
  Stringer Creek 6550   8.9   8.0  10.5   6-Apr  111   85   33     27
  Deadman Creek  6450   9.7   7.5   9.7   2-Apr  129  100   29     33
Basin Index                                      110   76

SUN, TETON AND MARIAS RIVER BASINS
  Dupuyer Creek  5750   1.6   6.4   9.2  11-Apr   25   17    7     23
  Waldron        5600   6.4   7.8  10.8   5-Apr   82   59   20     32
  Badger Pass    6900  23.4  21.8  31.3  13-Apr  107   75   65     36
Basin Index                                       89   64

MISSOURI MAINSTEM RIVER BASIN
  Dupuyer Creek  5750   1.6   6.4   9.2  11-Apr   25   17    7     23
  Badger Pass    6900  23.4  21.8  31.3  13-Apr  107   75   65     36
  Crystal Lake   6050   9.2   8.6  13.2  13-Apr  107   70   38     24
  Frohner Meadow 6480   5.8   5.4   7.6  11-Apr  107   76   17     34
  Deadman Creek  6450   9.7   7.5   9.7   2-Apr  129  100   29     33
Basin Index                                      103   72

ST. MARY AND MILK RIVER BASINS
  Many Glacier   4900   3.6  10.7  12.6  30-Mar   34   29   12     30
  Flattop Mtn.   6300  30.3  32.1  43.4  13-Apr   94   70   87     35
  Rocky Boy      4700   4.0   3.8   4.4  12-Mar  105   91   10     40
Basin Index                                       81   63

UPPER YELLOWSTONE RIVER BASIN
  Burnt Mtn      5880   1.8   3.7   4.8  25-Mar   49   38   10     18
  Fisher Creek   9100  26.0  24.1  34.4  12-May  108   76   81     32
  Two Ocean Plat 9240  21.5  20.0  29.9   4-May  108   72   67     32
  Beartooth Lake 9360  17.6  15.6  23.6  24-Apr  113   75   60     29
  Monument Peak  8850  15.9  14.1  21.6   9-May  113   74   56     28
  Brackett Creek 7320  19.4  13.4  20.8  15-Apr  145   93   57     34
Basin Index                                      110   74

LOWER YELLOWSTONE RIVER BASIN
  St Lawrence At 8620   3.0   4.8   6.9   8-Apr   62   43   17     17
  Burgess Jnctn  7880   8.1   7.6  12.7  22-Apr  107   64   37     22
  Sucker Creek   8880   8.8   8.2  12.7  24-Apr  107   69   40     22
  Dome Lake      8880   8.7   8.0  12.0  15-Apr  109   72   40     22
  Bear Trap Mdw  8200   6.5   3.9   5.2  24-Mar  167  125   34     19
Basin Index                                      105   68

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 sig
nificant 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.

The next spring outlook is scheduled for release on March 5th.

$$

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