Souris River Basin Flood Outlook...updated March 5th

Souris Basin

PROBABILISTIC HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE BISMARCK ND
0847 AM CST FRI MAR 5 2010

...FLOOD AND WATER RESOURCES OUTLOOK FOR THE SOURIS (MOUSE) RIVER
BASIN...

THIS OUTLOOK CONTAINS QUALITATIVE TEXT AND DETAILED PROBABILITY
TABLES WHICH DESCRIBE THE POTENTIAL FOR FLOODING IN THE SOURIS RIVER
BASIN OF NORTH CENTRAL NORTH DAKOTA DURING THE NEXT 90 DAYS.

...ADVANCED HYDROLOGIC PREDICTION SERVICES (AHPS) ENABLE THE
NATIONAL WEATHER SERVICE TO PROVIDE LONG-RANGE PROBABILISTIC RIVER
OUTLOOKS...

                 LONG-RANGE PROBABILISTIC OUTLOOK
                 VALID 9 MARCH 2010 - 7 JUNE 2010

THE THREE MONTH CLIMATE OUTLOOKS COVERING MARCH...APRIL...AND MAY
SHOW NO STRONG INDICATION OF ABOVE OR BELOW NORMAL CONDITIONS FOR
TEMPERATURE AND PRECIPITATION. THESE OUTLOOKS CAN BE VIEWED ON THE
INTERNET AT:

                   HTTP://WWW.CPC.NCEP.NOAA.GOV

AT THIS POINT...ALL RIVERS AND STREAMS REMAIN UNDER NORMAL WINTER
CONDITIONS AND SHOULD REMAIN THAT WAY UNTIL AT LEAST THE SECOND WEEK
OF MARCH.  AS WE ENTER THE MIDDLE OF MARCH THIS SHOULD START TO
CHANGE AS THIS PERIOD HISTORICALLY MARKS THE BEGINNING OF
THE SPRING MELT IN THE SOUTHERN AND SOUTHWESTERN PARTS OF NORTH
DAKOTA...WITH THE SOURIS RIVER BASIN TENDING TO BE IN ACTIVE MELT BY
THE THIRD OR FOURTH WEEK OF MARCH.

THE GOOD NEWS FOR MUCH OF WESTERN NORTH DAKOTA...INCLUDING THE
SOURIS BASIN...IS THE RELATIVELY DRY SECOND HALF OF FEBRUARY AND
EARLY MARCH.  THIS IS REFLECTED IN SLIGHTLY LOWER PROBABILITIES
FOR REACHING THE MODERATE AND MAJOR FLOOD STAGES IN MANY RIVER
GAUGES ACROSS THE BASIN.  HOWEVER...WHILE THE PROBABILITIES HAVE
LOWERED...SIGNIFICANT RISK REMAINS BASED UPON THE EXISTING WATER
CONTENT ACROSS THE BASIN AND THE UNCERTAINTY OF AMOUNT...TIMING...
AND LOCATION OF PRECIPITATION DURING MARCH.

EVEN THOUGH ONLY MODEST AMOUNTS OF MELTING ON CITY STREETS AND
HIGHWAYS HAVE BEEN OBSERVED...THE SOURIS RIVER BELOW LAKE DARLING
IS STARTING TO SLOWLY RISE AS RELEASES FROM LAKE DARLING ARE BEING
RAMPED UP IN ANTICIPATION OF HIGHER THAN NORMAL RUNOFF ABOVE THE
RESERVOIR. 

AS MINOT CONTINUES TO BE THE CENTER OF THE HEAVIEST SNOWPACK IN
THE SOURIS RIVER BASIN...THIS WILL MOST LIKELY TRANSLATE INTO A
HIGHER CONCERN FOR OVERLAND AND SMALL STREAM FLOODING AROUND
THE MINOT AREA...AND RIVER FLOODING FARTHER DOWNSTREAM AS THIS
WATER ENTERS THE SOURIS RIVER. 

THE PROBABILITIES OF FLOODING CONTAINED IN THIS HYDROLOGIC OUTLOOK
WERE DEVELOPED USING SNOWFALL AND SNOW WATER EQUIVALENT DATA CURRENT
THROUGH 2 MARCH 2010.  GIVEN THE SIGNIFICANTLY ABOVE NORMAL
SNOWPACK ACROSS MOST OF THE STATE...THE RISKS FOR FLOODING ARE ALSO
WELL ABOVE NORMAL AS WE APPROACH THE SPRING MELT SEASON. 

THE WILLOW CREEK AND WINTERING RIVER SITES OF WILLOW CITY
AND KARLSRUHE CONTINUE TO SHOW SIGNIFICANT PROBABILITIES OF MINOR TO
MODERATE MINOR FLOODING.   

ONE SHOULD NOTE THOUGH THAT WHILE THE SOURIS RIVER BASIN CURRENTLY
HAS A SNOWPACK SIMILAR TO THAT OF 2009 WHICH PRODUCED WIDESPREAD
FLOODING...THE EFFECT OF A VERY WET 2009 MARCH ON FLOODING SHOULD
NOT BE IGNORED.  MARCH OF 2009 WAS UNUSUALLY WET WITH MINOT HAVING
ITS NINTH WETTEST MARCH IN THE HISTORICAL RECORD.  OTHER LOCATIONS
THAT HAD WETTER MARCHES ALSO HAD MORE PROBLEMS WITH FLOODING AND
LOCATIONS WITH DRYER MARCHES EXPERIENCED THE LEAST PROBLEMS.

SO WHILE A HIGH DEGREE OF CERTAINTY EXISTS FOR SPRING FLOODING...
THE SEVERITY WILL STILL BE DETERMINED BY THE TIMING...LOCATION...
AND AMOUNT OF MARCH PRECIPITATION.

IMPORTANTLY...THE PROBABILITIES FOR FLOODING IN THIS HYDROLOGIC
OUTLOOK DO NOT INCLUDE RISK ASSOCIATED WITH ICE JAM RELATED
FLOODING.  TIMING AND SEVERITY OF ICE JAMS DEFY STATISTICAL
FORECASTING METHODS...ALTHOUGH ICE JAMS DO TEND TO FORM IN
HISTORICALLY KNOWN LOCATIONS TYPICALLY ASSOCIATED WITH BRIDGES...
MEANDERS IN CHANNEL...OR OTHER FEATURES THAT IMPEDE FLOW. 
 

TABLE 1 SHOWS THE PROBABILITY OF EXCEEDING THE DEFINED FLOOD STAGES.
FOR MORE DETAILS SUCH AS CHANCES OF EXCEEDING CERTAIN STAGES AT
SPECIFIC LOCATIONS REFER TO TABLE 2.


   
    TABLE 1. CHANCES OF EXCEEDING FLOOD STAGE AT SPECIFIC           
             LOCATIONS IN THE SOURIS RIVER BASIN.


             VALID 9 MARCH 2010 - 7 JUNE 2010

                                                          DEPARTURE
                         ---------FLOOD STAGES---------   FROM NORMAL
                         MINOR     MODERATE    MAJOR      OF REACHING 
LOCATION                 STG  PCT   STG  PCT   STG  PCT   FLOOD STAGE
---------------------------------------------------------------------
DES LACS RIVER
  FOXHOLM                16   4%    18   3%    19   1%    NEAR NORMAL
SOURIS RIVER
  SHERWOOD 15W           18  23%    20  13%    25  ---    NEAR NORMAL
  FOXHOLM 3E             10  57%    13  44%    15   3%    18% GREATER
  MINOT 4NW              14  47%    17  13%    22   3%    25% GREATER
  MINOT-BRDWY BRDG     1549   8%  1551   4%  1555   1%    NEAR NORMAL
  LOGAN                  34  73%    36  36%    38   1%    50% GREATER
  SAWYER                 22  68%    24  26%    26   4%    45% GREATER
  VELVA                1505  70%  1510   3%  1515  ---    46% GREATER
WINTERING RIVER
  KARLSRUHE 6N            7  96%     9   1%    10  ---    88% GREATER
SOURIS RIVER
  TOWNER                 52 >98%    54  96%    56   9%            NA
  BANTRY 8E              11 >98%    12 >98%    14   6%            NA
WILLOW CREEK
  WILLOW CITY 7W         10  96%    14  55%    16   9%    59% GREATER
SOURIS RIVER
WESTHOPE 7NNE            10 >98%    14  57%    16  24%            NA

FS  = FLOOD STAGE
--- = STATISTICAL DISTRIBUTION COMPLETELY BELOW THIS STAGE
NA  = NOT APPLICABLE

IN TABLE 2 BELOW...THE 90 THROUGH 10 PERCENT COLUMNS GIVE THE CHANCE THE
RIVER AT THE GIVEN LOCATION WOULD RISE ABOVE THE INDICATED STAGE LEVELS
WITHIN THE NEXT 90 DAYS.

EXAMPLE: DES LACS RIVER AT FOXHOLM HAS A FLOOD STAGE OF 16 FEET. IN
THE NEXT THREE MONTHS THERE IS A 90 PERCENT CHANCE THAT THE RIVER
WILL RISE TO AT LEAST 8.9 FEET...BUT ONLY A 10 PERCENT CHANCE THAT IT
WILL RISE ABOVE 14.5 FEET.

     TABLE 2. CHANCES OF EXCEEDING STAGES AT SPECIFIC LOCATIONS IN THE
     BISMARCK HYDROLOGIC SERVICE AREA.

                            ALL STAGES ARE IN FEET
                       VALID 9 MARCH 2010 - 7 JUNE 2010

LOCATION   FS (FT)   90%    80%    70%    60%    50%    40%    30%    20%    10%
________   ______    ___    ___    ___    ___    ___    ___    ___    ___    ___
DES LACS RIVER
FOXHOLM       16     8.9    9.5    9.9   10.6   11.0   11.4   12.3   12.9   14.5
SOURIS RIVER
SHERWOOD 15W  18     7.0    8.5    9.2   10.7   12.2   15.5   17.3   19.2   21.4
FOXHOLM 3E    10     7.6    8.1    8.5    9.5   11.9   13.2   13.8   14.2   14.4
MINOT 4NW     14    10.1   11.0   12.7   13.4   13.9   14.4   15.4   16.5   18.4
MINOT BWY BR 1549 1543.5 1543.8 1544.7 1545.1 1545.3 1545.7 1546.2 1547.0 1548.6
LOGAN         36    31.1   32.6   34.8   35.5   35.7   35.8   36.2   36.8   37.1
SAWYER        22    18.1   19.7   21.8   22.5   23.0   23.4   23.9   24.7   25.4
VELVA        1505 1501.8 1503.2 1505.0 1505.7 1506.2 1506.6 1506.8 1507.6 1508.5
TOWNER 1NW    52    54.4   54.7   55.0   55.2   55.3   55.4   55.5   55.7   56.0
BANTRY 8E     11    12.5   12.7   12.9   13.0   13.1   13.2   13.3   13.5   13.8
WESTHOPE 7NNE 10    12.0   12.4   13.4   13.9   14.6   15.1   15.8   16.5   17.8

WINTERING RIVER
KARLSRUHE 5NE  7     7.3    7.6    7.7    7.9    8.0    8.1    8.3    8.5    8.6

WILLOW CREEK
WILLOW CITY 7W 10   11.8   12.6   13.5   13.9   14.2   14.5   15.0   15.4   16.1

 
TABLE 3 PROVIDES PROBABILISTIC FORECASTS FOR "HOW LOW COULD THE RIVER GO?"
THIS FEATURE IS INCLUDED ON OUR AHPS WEB PAGES FOR EACH FORECAST POINT IN
THE SOURIS RIVER BASIN THAT HAS PROBABILISTIC GRAPHICS PRODUCED FOR THEM.
PROBABILISTIC LOW FLOW INFORMATION PROVIDES USEFUL INFORMATION DURING
DROUGHTS...AND FOR RIVER USERS INTERESTED IN FISHERIES...INDUSTRIAL
DISCHARGES...DILUTION RATIOS...RECREATION...IRRIGATION...AND NAVIGATION.
IT AIDS IN ASSESSING RISK DURING SITUATIONS WHERE LOW FLOWS MAY BE
CRITICAL TO OPERATIONS.

TABLE 3. CHANCES OF FALLING BELOW INDICATED STAGE AT SPECIFIC LOCATIONS IN THE
BISMARCK HYDROLOGIC SERVICE AREA.

                           ALL STAGES ARE IN FEET
                      VALID 9 MARCH 2010 - 7 JUNE 2010

LOCATION    FS (FT)  10%    20%    30%    40%    50%    60%    70%    80%    90%
________    _______  ___    ___    ___    ___    ___    ___    ___    ___    ___

DES LACS RIVER
FOXHOLM       16     4.5    4.5    4.5    4.5    4.5    4.5    4.5    4.5    4.5

SOURIS RIVER
SHERWOOD 15W  18     0.9    0.9    0.9    0.9    0.9    0.9    0.9    0.9    0.9
FOXHOLM 3E    10     4.5    4.5    4.6    4.6    4.6    4.6    4.7    5.0    5.4
MINOT 4NW     14     3.8    3.8    3.8    3.8    4.1    4.2    4.3    4.5    4.6
MINOT BWY BR 1549 1532.0 1532.0 1532.0 1532.1 1536.8 1537.4 1538.4 1539.3 1539.7
LOGAN         36    18.7   18.7   18.7   19.0   20.3   20.6   21.0   21.9   22.4
SAWYER        22     5.3    5.3    5.3    5.5    6.3    6.6    6.7    7.3    7.7
VELVA        1505 1489.0 1489.0 1489.0 1489.0 1489.9 1490.3 1490.5 1491.0 1491.2
TOWNER 1NW    52    43.2   43.2   43.2   43.2   43.2   43.2   43.2   43.2   43.2
BANTRY 8E     11     1.4    1.4    1.4    1.4    1.4    1.4    1.4    1.4    1.4
WESTHOPE 7NNE 10     5.4    5.4    5.4    5.5    5.6    6.0    6.3    6.6    6.8


WINTERING RIVER
KARLSRUHE 5NE  7     2.7    2.7    2.7    2.7    2.7    2.7    2.7    2.7    2.7

WILLOW CREEK
WILLOW CITY 7W 10    4.9    4.9    4.9    4.9    4.9    4.9    4.9    4.9    4.9


THE NUMBERS CONTAINED IN TABLE 3 REPRESENT NATURAL FLOWS. THAT
IS...FLOW UNAFFECTED BY MAN-MADE STRUCTURES IN THE BASIN SUCH AS
DIVERSION DAMS AND RESERVOIRS.  

THIS LONG-RANGE PROBABILISTIC OUTLOOK CONTAINS FORECAST VALUES THAT
ARE CALCULATED USING HISTORICAL WEATHER PATTERNS FROM 30 OR MORE
YEARS OF CLIMATOLOGICAL DATA WITH CURRENT CONDITIONS OF THE
RIVER...SNOWPACK...AND SOIL MOISTURE. BY PROVIDING THE COMPLETE
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.

THIS OUTLOOK IN GRAPHICAL FORM ALONG WITH GRAPHS OF STAGE...FLOW...
AND VOLUME ARE AVAILABLE ON THE NATIONAL WEATHER SERVICE WEBSITE. 
OTHER USEFUL LINKS INCLUDING EXPLANATIONS OF THIS PRODUCT AND
CURRENT INFORMATION FOR ALL 13 RIVER FORECAST POINTS IN THE SOURIS
RIVER BASIN ARE AVAILABLE ON OUR WEB SITE. FIVE-DAY FORECASTS ARE
ALSO AVAILABLE WHEN THE RIVER AT A FORECAST POINT IS NEAR OR ABOVE
FLOOD STAGE.

VISIT OUR HOME PAGE AT: HTTP://WWW.WEATHER.GOV/BIS FOR MORE WEATHER
AND FLOOD INFORMATION.

THE NEXT AHPS FORECAST WILL BE ISSUED 19 MARCH 2010. 

IF YOU HAVE ANY QUESTIONS...CONTACT THE NWS AT 701-250-4495.

$$

 


 
 


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