Flood Potential Outlook
Issued by NWS Bismarck, ND

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NDC001-007-011-015-021-025-029-031-033-037-041-043-045-047-051-
053-055-057-059-065-083-085-087-089-093-103-105-301800-

PROBABILISTIC HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE BISMARCK ND
1210 PM CDT WED MAR 27 2013


...FLOOD AND WATER RESOURCES OUTLOOK...

THIS PROBABILISTIC FLOOD OUTLOOK IS FOR THE MISSOURI AND JAMES RIVER
BASINS OF WESTERN AND CENTRAL NORTH DAKOTA...COVERING THE TIME PERIOD
OF MARCH 30 THROUGH JUNE 28 2013.

THE FOLLOWING MESSAGE HAS THREE 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 FINAL SECTION GIVES THE CURRENT CHANCES
OF RIVER LOCATIONS RISING ABOVE LISTED RIVER STAGES.


...FLOOD OUTLOOK OVERVIEW HIGHLIGHTS...

ALL FORECAST POINTS WITHIN THE MISSOURI AND JAMES RIVER BASINS
IN NORTH DAKOTA HAVE A LOW RISK OF FLOODING FROM SNOW MELT.
THE MAJORITY OF LOCATIONS HAVE A BELOW NORMAL RISK FOR FLOODING
WHEN COMPARED TO THEIR HISTORICAL AVERAGES.


...CURRENT CONDITIONS...

THE VERY THIN AMOUNTS OF SNOW THAT REMAIN ACROSS THE
CANNONBALL...HEART...KNIFE...LITTLE MISSOURI...APPLE CREEK...
AND BEAVER CREEK BASINS WILL RAPIDLY BE DEPLETED AND LARGELY
INFILTRATE INTO THE GROUND AS THE TOP SOIL THAWS.

THE JAMES RIVER BASIN STILL CONTAINS AN APPRECIABLE SNOWPACK
WITH APPROXIMATELY TWO TO FOUR INCHES OF SNOW WATER EQUIVALENT.
FROST DEPTHS ACROSS THE BASIN ARE IN 35 TO 40 INCH RANGE WITH
TOP SOILS WETTED BY FALL RAINS. THIS MAY ACT TO ENAHNCE RUNOFF
UNTIL THE TOP SOIL AND ANY ICE LAYERS AT THE BOTTOM OF THE
SNOWPACK CAN THAW.

...WEATHER OUTLOOK...

TEMPERATURES ARE FORECAST TO TREND NEAR NORMAL IN MARCH 28
TO 30 TIMEFRAME ACROSS MUCH OF THE MISSOURI BASIN WITH HIGHS
IN THE 40S. GIVEN THE IMPACT FROM THE SNOWPACK...TEMPERATURES
ACROSS THE JAMES BASIN FOR THIS TIMEFRAME ARE EXPECTED TO BE
SLIGHTLY BELOW NORMAL IN THE MID TO UPPER 30S. A COOL DOWN
IS POSSIBLE FOR LATE SUNDAY INTO TUESDAY WITH SUB-FREEZING
HIGHS ACROSS THE JAMES RIVER BASIN. THEREAFTER FOR APRIL 3
THROUGH 8...LONG RANGE OUTLOOKS FAVOR BELOW NORMAL
TEMPERATURES AND THE CHANCE OF ABOVE NORMAL PRECIPITATION.


...SUMMARY OF HYDROLOGIC CONDITIONS...

ICE IN RIVER AND STREAM SYSTEMS IN THE MISSOURI BASIN IS
LIMITED AT BEST. THE JAMES BASIN DOES REMAIN ICE COVERED
AND THIS WILL POSE AN ICE JAM THREAT ONCE RUNOFF COMMENCES
AND THE ICE IS LIFTED AND POTENTIALLY BREAKS UP.


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

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.



                    JAMES AND MISSOURI RIVER BASINS
                    LONG-RANGE PROBABILISTIC OUTLOOK

        PROBABILITIES FOR MINOR...MODERATE AND MAJOR FLOODING
                    FROM  3/30/2013 TO 6/28/2013 Z

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
--------            ------ ------ ------ : --- ---  --- ---  --- ---
LITTLE MUDDY CREEK.....
  WILLISTON           10.0   12.0   14.0 :  22  52   <5  21   <5   6
LITTLE MISSOURI RIVER.....
  MARMARTH            18.0   23.0   30.0 :  <5   5   <5  <5   <5  <5
  MEDORA              15.0   18.0   20.0 :  <5   7   <5   6   <5   5
  WATFORD CITY        20.0   24.0   30.0 :  <5  <5   <5  <5   <5  <5
KNIFE RIVER.....
  MANNING             15.0   17.0   20.0 :   6  18   <5  <5   <5  <5
SPRING CREEK.....
  ZAP                 14.0   18.0   20.0 :   5  18   <5   5   <5  <5
KNIFE RIVER.....
  HAZEN               21.0   24.0   25.0 :   7  30   <5  11   <5   7
HEART RIVER.....
  MANDAN              17.0   23.0   28.0 :  <5   6   <5  <5   <5  <5
APPLE CREEK.....
  MENOKEN             15.0   16.0   17.0 :  37  55   27  44    6  22
CANNONBALL RIVER.....
  REGENT              22.0   24.0   26.0 :  <5  <5   <5  <5   <5  <5
CEDAR CREEK.....
  RALEIGH             12.0   14.0   16.0 :  <5  <5   <5  <5   <5  <5
CANNONBALL RIVER.....
  BREIEN              10.0   20.0   23.0 :   8  33   <5  <5   <5  <5
BEAVER CREEK.....
  LINTON               9.0   11.0   13.0 :  36  45   22  33   14  19
JAMES RIVER.....
  GRACE CITY          12.0   14.0   15.0 :  <5  10   <5   6   <5   5
PIPESTEM CREEK.....
  PINGREE              9.0   11.0   13.0 :  12  13   <5   8   <5  <5
JAMES RIVER.....
  LAMOURE             14.0   16.0   18.0 :   5   9   <5   5   <5  <5

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


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


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
         50 PERCENT CHANCE FOR THE LITTLE MUDDY CREEK AT WILLISTON
         TO RISE ABOVE ____ FEET AND ONLY A 10 PERCENT CHANCE THAT
         IT WILL RISE ABOVE ___ FEET.


                    JAMES AND MISSOURI RIVER BASINS
                    LONG-RANGE PROBABILISTIC OUTLOOK
           PROBABILITIES FOR EXCEEDING LISTED RIVER STAGES
                                 FROM
TABLE 2

LOCATION              95%    90%    75%    50%    25%    10%    05%
--------            ------ ------ ------ ------ ------ ------ ------
LITTLE MUDDY CREEK.....
  WILLISTON            7.4    7.6    8.3    8.9    9.6   11.2   11.7
LITTLE MISSOURI RIVER.....
  MARMARTH             1.8    1.8    1.8    2.9    4.1    8.0    8.3
  MEDORA               1.9    1.9    2.2    3.1    4.8    8.8    9.0
  WATFORD CITY         1.0    1.0    1.0    2.0    4.0    5.0    5.6
KNIFE RIVER.....
  MANNING              7.3    7.3    7.4    8.7   10.7   13.4   15.5
SPRING CREEK.....
  ZAP                  5.4    5.5    6.0    8.7   11.3   12.2   13.9
KNIFE RIVER.....
  HAZEN                3.1    3.1    4.5    9.4   14.1   16.9   23.2
HEART RIVER.....
  MANDAN               1.9    2.0    2.3    3.4    6.6    8.4   10.0
APPLE CREEK.....
  MENOKEN              5.7    5.7    6.5    9.6   16.1   16.6   17.3
CANNONBALL RIVER.....
  REGENT               2.0    2.0    2.5    6.6    8.0   10.2   10.9
CEDAR CREEK.....
  RALEIGH              1.1    1.3    2.2    3.8    4.7    5.4    6.1
CANNONBALL RIVER.....
  BREIEN               5.3    5.3    5.4    6.9    8.3    9.7   11.1
BEAVER CREEK.....
  LINTON               5.7    5.8    6.3    7.0   10.4   14.3   15.4
JAMES RIVER.....
  GRACE CITY           4.8    4.9    5.2    5.6    6.5    8.5    9.4
PIPESTEM CREEK.....
  PINGREE              5.3    5.4    5.7    6.0    7.5   10.2   10.6
JAMES RIVER.....
  LAMOURE              8.7    8.7    8.7    8.8    9.3   10.0   13.8


...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 25 OR MORE YEARS OF PAST PRECIPITATION AND
TEMPERATURE CONDITIONS IN THE HISTORICAL RECORD. THESE CRESTS CAN
THEN BE RANKED FROM LOWEST TO HIGHEST...AND 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 1978 THROUGH 2002.

. 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.


$$

AYD
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