National Weather Service Text Product Display

Flood Potential Outlook
Issued by NWS Bismarck, ND
Versions: 1 2 3 4 5 6 7 8
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FGUS73 KBIS 041955
ESFBIS
NDC009-013-023-049-061-069-075-079-101-101800-

PROBABILISTIC HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE BISMARCK ND
246 PM CDT THU APR 4 2013

...FLOOD AND WATER RESOURCES OUTLOOK...

THIS PROBABILISTIC FLOOD OUTLOOK IS FOR THE SOURIS (MOUSE) RIVER
BASIN OF WESTERN AND CENTRAL NORTH DAKOTA...COVERING THE TIME PERIOD
OF APRIL 10 THROUGH JULY 9.

THE FOLLOWING MESSAGE HAS FOUR SECTIONS...THE FIRST PROVIDES SOME
TEXT ON HIGHLIGHTS OF THIS PRODUCT AND CONDITIONS AFFECTING LOCAL
HYDROLOGY. THE SECOND GIVES THE CURRENT AND NORMAL/HISTORICAL
CHANCES OF RIVER LOCATIONS REACHING THEIR MINOR...MODERATE AND
MAJOR FLOOD CATEGORY...THE THIRD GIVES THE CURRENT CHANCES OF
RIVER LOCATIONS RISING ABOVE RIVER STAGES LISTED...AND THE FINAL
SECTION COVERS THE RISK OF RIVERS FALLING BELOW LISTED STAGES.

...FLOOD OUTLOOK OVERVIEW HIGHLIGHTS...

THIS OUTLOOK CONTAINS UPDATED PROBABILISTIC TABLES FOR THE RISKS
ASSOCIATED WITH REACHING THE DEFINED FLOOD STAGES. THE SPRING
SNOWMELT IS LATE THIS YEAR AND HAS CREATED AN ENHANCED RISK OF
REACHING MINOR AND MODERATE DEFINITIONS OF FLOODING...BUT NOT MUCH
EXTRA RISK OF REACHING MAJOR FLOOD STAGE. IMPORTANT IN UNDERSTANDING
THESE NUMBERS IS THAT THE RISKS PRESENTED DO NOT INCORPORATE THE
CURRENT RELEASES FROM THE UPSTREAM RESERVOIRS. INSTEAD THESE NUMBERS
ARE BASED ON THE EVENTUAL DRAWDOWN LEVELS OF THE RESERVOIRS AND USE
OF THAT EXTRA STORAGE TO DAMPEN THE EVENTUAL SPRING MELT PEAKS.

...CURRENT CONDITIONS...

THE SOURIS RIVER IS STILL LARGELY FROZEN OVER AND NOT RECEIVING ANY
SIGNIFICANT RUNOFF FROM SNOW MELTWATER. HIGHER WATER LEVELS ALONG THE
SOURIS RIVER OVER THE PAST TWO WEEKS ARE DUE TO RELEASES FROM
UPSTREAM DAMS AS THEY ARE BEING DRAWN DOWN TO INCREASE FLOOD STORAGE.

...WEATHER OUTLOOK...

THE 6 TO 10 AND 8-14 DAY AND ONE-MONTH OUTLOOKS ALL FAVOR BELOW
NORMAL TO NEAR NORMAL TEMPERATURES...AND NORMAL PRECIPITATION.

...SUMMARY OF HYDROLOGIC CONDITIONS...

SUBSTANTIAL INCREASES IN FLOW OUT OF RAFFERTY...BOUNDARY...AND
ALAMEDA DAM IN SASKATCHEWAN HAVE PROMPTED INCREASED FLOWS OUT OF LAKE
DARLING IN NORTH DAKOTA. THESE FLOWS ARE MAKING THEIR WAY THROUGH THE
SOURIS RIVER OF NORTH DAKOTA AND ARE PUSHING AN ICE COVERED SOURIS TO
FLOOD STAGE...OR NEAR FLOOD STAGE...AT ALL LOCATIONS. SO FAR THERE
HAVE BEEN NO ICE RELATED FLOOD PROBLEMS REPORTED...BUT THE HIGHER
WATER LEVELS HAVE INCREASED THE RISK OF ICE RELATED FLOODING.


...LONG-RANGE PROBABILISTIC RIVER OUTLOOK BY FLOOD CATEGORY...


                           SOURIS RIVER BASIN
                    LONG-RANGE PROBABILISTIC OUTLOOK
               VALID FROM APRIL 10, 2013  TO JULY 9, 2013

THE TABLE BELOW GIVES BOTH THE CURRENT CHANCES (CS) AND THE
NORMAL/HISTORICAL CHANCES (HS) FOR EXCEEDING THE MINOR...MODERATE
AND MAJOR FLOOD STAGES AT THE RIVER FORECAST POINT LOCATIONS DURING
THE VALID PERIOD OF THIS OUTLOOK.

        PROBABILITIES FOR MINOR...MODERATE AND MAJOR FLOODING
                     FROM  4/10/2013 TO 7/9/2013

TABLE 1                                  : CURRENT AND HISTORICAL
                                         : CHANCES OF EXCEEDING FLOOD
                                         : CATEGORY IN PERCENT (%)
                         CATEGORICAL     :
                      FLOOD STAGES (FT)  :  MINOR   MODERATE  MAJOR
LOCATION            MINOR    MOD   MAJOR :  CS HS    CS HS    CS HS
--------            ------ ------ ------ : --- ---  --- ---  --- ---
DES LACS RIVER.....
  FOXHOLM             16.0   18.0   19.0 :  29  <5    8  <5   <5  <5
SOURIS RIVER.....
  SHERWOOD            18.0   20.0   25.0 : >95  <5  >95  <5   <5  <5
  SOURIS NR FOXHOLM   10.0   13.0   15.0 : >95  41  >95  31   21  <5
  MINOT 4NW           14.0   17.0   22.0 : >95  16   42  <5   <5  <5
  MINOT             1549.0 1551.0 1555.0 :  19  <5    6  <5   <5  <5
  LOGAN               34.0   36.0   38.0 : >95  19   34   6   <5  <5
  SAWYER              22.0   24.0   26.0 : >95  18  >95   9   <5  <5
  VELVA             1505.0 1510.0 1515.0 : >95  13   <5  <5   <5  <5
WINTERING RIVER.....
  KARLSRUHE            7.0    9.0   10.0 :  50   6   <5  <5   <5  <5
SOURIS RIVER.....
  TOWNER              52.0   54.0   56.0 : >95  59  >95  44   37   8
  BANTRY              11.0   12.0   14.0 : >95  59  >95  49   26  <5
WILLOW CREEK.....
  WILLOW CITY         10.0   14.0   16.0 : >95  36   80  11   24  <5
SOURIS RIVER.....
  WESTHOPE            10.0   14.0   16.0 : >95  52  >95  19   90  16

LEGEND:
    CS  =  CONDITIONAL SIMULATION (OUTLOOK FOR CURRENT CONDITIONS)
    HS  =  HISTORICAL SIMULATION  (HISTORICAL RISK FOR THIS SEASON)
    FT  =  FEET ABOVE GAGE ZERO DATUM


...LONG-RANGE PROBABILISTIC OUTLOOK BY RIVER STAGE...


                          SOURIS RIVER BASIN
                    LONG-RANGE PROBABILISTIC OUTLOOK

THE TABLE BELOW GIVES THE CURRENT 95 THROUGH 5 PERCENT CHANCES FOR
EXCEEDING RIVER STAGES AT THE RIVER FORECAST POINT LOCATIONS DURING
THE VALID PERIOD OF THIS OUTLOOK.

EXAMPLE: DURING THE VALID TIME OF THIS OUTLOOK...THERE IS A
         95 PERCENT CHANCE FOR THE SOURIS RIVER AT SHERWOOD TO
         RISE ABOVE 20.8 FEET AND ONLY A 10 PERCENT CHANCE THAT
         IT WILL RISE ABOVE 17.6 FEET.

           PROBABILITIES FOR EXCEEDING LISTED RIVER STAGES
                     FROM  4/10/2013 TO 7/9/2013
TABLE 2

LOCATION              95%    90%    75%    50%    25%    10%    05%
--------             -----  -----  -----  -----  -----  -----  -----
DES LACS RIVER.....
  FOXHOLM             12.7   13.2   14.1   15.0   16.6   17.6   18.5
SOURIS RIVER.....
  SHERWOOD            20.8   21.3   21.8   22.1   22.9   23.3   23.6
  SOURIS NR FOXHOLM   14.5   14.6   14.7   14.7   14.9   15.9   16.8
  MINOT 4NW           16.1   16.1   16.2   16.4   17.8   19.1   20.5
  MINOT             1546.7 1546.7 1546.7 1546.9 1548.7 1549.7 1551.8
  LOGAN               35.4   35.4   35.5   35.6   36.3   36.9   37.0
  SAWYER              24.1   24.1   24.2   24.4   25.0   25.5   25.7
  VELVA             1505.7 1505.7 1505.8 1506.1 1507.0 1507.9 1508.4
WINTERING RIVER.....
  KARLSRUHE            6.2    6.4    6.6    7.1    7.7    8.5    8.5
SOURIS RIVER.....
  TOWNER              55.5   55.5   55.6   55.8   56.2   56.5   57.1
  BANTRY              13.3   13.3   13.4   13.6   14.0   14.3   14.5
WILLOW CREEK.....
  WILLOW CITY         12.8   13.5   14.3   15.2   16.1   17.1   17.5
SOURIS RIVER.....
  WESTHOPE            14.9   16.1   16.7   18.2   19.4   21.4   23.1



...LONG-RANGE PROBABILISTIC OUTLOOK BY RIVER STAGE...


                          SOURIS RIVER BASIN
                    LONG-RANGE PROBABILISTIC OUTLOOK

THE TABLE BELOW GIVES THE CURRENT 95 THROUGH 5 PERCENT CHANCES FOR
THE RIVERS TO FALL BELOW THE LISTED RIVER STAGES AT THE RIVER
FORECAST POINT LOCATIONS DURING THE VALID PERIOD OF THIS OUTLOOK.

EXAMPLE: DURING THE VALID TIME OF THIS OUTLOOK...THERE IS A
         95 PERCENT CHANCE FOR THE SOURIS RIVER AT SHERWOOD TO
         REMAIN ABOVE 1.8 FEET AND ONLY A 5 PERCENT CHANCE THAT
         IT WILL FALL BELOW 1.1 FEET.

         PROBABILITIES FOR FALLING BELOW LISTED RIVER STAGES
                         4/10/2013 - 7/9/2013

TABLE 3

LOCATION              95%    90%    75%    50%    25%    10%    05%
--------             -----  -----  -----  -----  -----  -----  -----
DES LACS RIVER.....
  FOXHOLM              6.0    5.9    5.5    4.8    4.5    4.4    4.4
SOURIS RIVER.....
  SHERWOOD             1.8    1.7    1.1    1.1    1.1    1.1    1.1
  SOURIS NR FOXHOLM    5.0    4.7    4.7    4.5    4.5    4.5    4.5
  MINOT 4NW            5.0    4.8    4.4    4.1    3.9    3.9    3.8
  MINOT             1541.2 1540.4 1538.2 1537.3 1536.6 1535.6 1535.5
  LOGAN               23.8   23.2   20.9   20.0   19.2   18.8   18.8
  SAWYER               9.3    8.9    6.7    6.4    5.8    5.4    5.4
  VELVA             1491.9 1491.8 1490.7 1490.2 1489.4 1489.0 1489.0
WINTERING RIVER.....
  KARLSRUHE            2.4    2.3    2.0    1.2    1.2    1.2    1.2
SOURIS RIVER.....
  TOWNER              43.2   43.2   43.2   43.2   43.2   43.2   43.2
  BANTRY               2.0    1.8    1.7    1.7    1.7    1.7    1.7
WILLOW CREEK.....
  WILLOW CITY          4.9    4.6    4.6    4.6    4.6    4.6    4.6
SOURIS RIVER.....
  WESTHOPE             7.2    6.8    6.3    5.7    5.6    5.5    5.4


...THE OUTLOOK PRODUCTION PROCESS...

THIS LONG RANGE PROBABILISTIC OUTLOOK IS BASED ON A SERIES OF PEAK
RIVER LEVELS OR CRESTS TAKEN FROM THE FORECAST HYDROGRAPH RESULTS
OF THE NWS ENSEMBLE STREAMFLOW PREDICTION MODEL (ESP). THE MODEL
IS RUN FOR MULTIPLE SCENARIOS STARTING AT CURRENT RIVER...SNOW AND
SOIL CONDITIONS AND USING NEARLY 50 YEARS OF PAST PRECIPITATION AND
TEMPERATURE CONDITIONS IN THE HISTORICAL RECORD. THESE CRESTS CAN
THEN
BE RANKED FROM LOWEST TO HIGHEST...AND THEN BE ASSIGNED AN
EXCEEDANCE PROBABILITY. FOR EXAMPLE...FOR A SERIES OF 50 YEARS...
THE LOWEST RANKED CREST HAS 49 CRESTS ABOVE IT AND SINCE 95 PERCENT
OF THE CRESTS ARE ABOVE IT... IT IS ASSIGNED A 95 PERCENT
PROBABILITY OF EXCEEDANCE (POE).

THE PROBABILITIES CAN BE USED FOR RISK MANAGEMENT BY COMPARING THIS
YEARS CURRENT TEMPERATURE AND PRECIPITATION OUTLOOKS WITH
THOSE OF PAST YEARS USED IN THE HYDRO OUTLOOK. THEY CAN ALSO BE
USED AS AN INDICATION OF THE RANGE OF CRESTS THAT MAY BE EXPECTED
DURING THE VALID PERIOD OF THE OUTLOOK.

BY PROVIDING A RANGE OF PEAK RIVER LEVEL PROBABILITIES..THE NWS IS
IS CONTRIBUTING TO THE AREAS DECISION SUPPORT SERVICES THAT HELP
WITH LONG RANGE FLOOD PLANNING AND RESPONSE READINESS.  THIS OUTLOOK
IS A PART OF NOAA/S NATIONAL WEATHER SERVICE/S AHPS (ADVANCED
HYDROLOGIC PREDICTION SERVICES).

THIS OUTLOOK WAS PRODUCED USING PRECIPITATION AND TEMPERATURES
FOR THE YEARS 1948 THROUGH 2006.

...ADDITIONAL INFORMATION SOURCES...

THE AHPS LONG RANGE PROBABILISTIC HYDROLOGIC OUTLOOKS ARE ISSUED
NEAR THE END OF EACH MONTH. HOWEVER...SPRING FLOOD AND WATER
RESOURCES OUTLOOKS ARE ISSUED SEVERAL TIMES DURING THE CRITICAL
SPRING MELT PERIOD...USUALLY ON THURSDAYS BEGINNING IN LATE
FEBRUARY OR EARLY MARCH AND ENDING IN EARLY APRIL...DEPENDING
ON THE SPRING FLOODING CONDITIONS.

THIS OUTLOOK IS ALSO PRESENTED AS GRAPHS OF THE PROBABILITY OF STAGE
EXCEEDANCE FOR THE FULL PERIOD AND FOR WEEKLY INTERVALS DURING THE
PERIOD. THESE GRAPHS...TOGETHER WITH EXPLANATIONS THAT HELP IN
INTERPRETING THEM ARE AVAILABLE FROM THE NWS BISMARCK AHPS WEB
PAGE ON THE INTERNET AT:

        WWW.WEATHER.GOV/BISMARCK OR WEATHER.GOV/BIS

  THEN CLICK ON THE "RIVERS AND LAKES AHPS"ON THE TAB ABOVE THE
MAP...
  OR ON THE LINK IN THE BLUE-LEFT-HAND BANNER.

CURRENT RIVER CONDITIONS FOR ALL FORECAST POINTS WITHIN THE SOURIS
RIVER BASIN ARE AVAILABLE ON OUR WEB SITE...AS WELL AS THE FORECASTS
WHEN THE RIVER AT THE FORECAST POINT IS IN OR NEAR FLOOD.

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

PROBABILISTIC HYDROLOGIC OUTLOOKS WILL BE ISSUED MONTHLY THROUGHOUT
THE REST OF THE YEAR DURING THE LATER PART OF THE MONTH OR AS
CONDITIONS WARRANT.


$$
AJS
National Weather Service Weather Forecast Office
