PROBABILISTIC HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE BISMARCK ND
ISSUED WED OCT 30, 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 OCTOBER THROUGH LATE DECEMBER.
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…
THE RISK OF FLOODING DURING THIS TIME OF YEAR IS QUITE LOW.
HOWEVER…WHILE NOT INCLUDED IN THE BELOW TABULAR DATA…EARLY WINTER
IS A TIME OF THE YEAR WHEN ICE FORMATION CAN PRODUCE UNUSUALLY HIGH
WATER. THIS WOULD BE THE MOST LIKELY CAUSE OF ANY FLOODING DURING
THE VALID PERIOD OF LATE OCTOBER THROUGH LATE JANUARY…ESPECIALLY
ON THE MISSOURI RIVER.
…CURRENT CONDITIONS…
THE UNUSUALLY WET FALL HAS LEFT THE REGION WITH SOME OF THE HIGHEST
SOIL MOISTURE LEVELS IN RECENT YEARS. THIS ALSO PRODUCES STRONG
BASEFLOW INTO LOCAL STREAMS AND RIVERS…SUGGESTING THEY WILL
EVENTUALLY ICE OVER AT HIGHER THAN NORMAL LEVELS. ALONG WITH THE
HIGH SOIL MOISTURE…WETLANDS ARE ALSO AT OR ABOVE NORMAL LEVELS
FOR THIS TIME OF YEAR.
…WEATHER OUTLOOK…
IN THE SHORTER 6 TO 10 AND 8 TO 14 DAY OUTLOOKS…THE COOLER THAN
NORMAL WEATHER IS LIKELY TO CONTINUE WITH NEAR NORMAL TO ABOVE
NORMAL PRECIPITATION. A NEUTRAL EL NINO SOUTHERN OSCILLATION
PROVIDES LITTLE IN THE WAY OF CLIMATE EXPECTATIONS FOR THE COMING
WINTER. THIS LACK OF A SIGNIFICANT CLIMATE SIGNAL PUTS THE REGION
IN THE EQUAL CHANCES CATEGORY FOR ABOVE NORMAL…NORMAL…OR BELOW
NORMAL TEMPERATURES AND PRECIPITATION.
…SUMMARY OF HYDROLOGIC CONDITIONS…
THE ABNORMALLY HIGH SOIL MOISTURE AND WETLANDS SUGGEST A GREATER RISK
OF PROBLEMATIC HIGH WATER COME NEXT SPRING AS FROZEN WET SOILS ARE
MUCH LESS PERMEABLE THAN COLD DRY SOILS. HOWEVER…THIS IS ONLY ONE
OF SEVERAL RISK FACTORS THAT WILL EVENTUALLY DICTATE SNOWMELT RUNOFF
NEXT SPRING. EVENTUAL WATER CONTENT OF THE SNOWPACK AND MELT CONDITIONS
WILL REMAIN UNCERTAIN UNTIL WE ARE MUCH CLOSER TO SPRING.
…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 10/26/2013 TO 1/24/2014 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 : 5 5 5 5 5 5
LITTLE MISSOURI RIVER…..
MARMARTH 18.0 23.0 30.0 : 5 5 5 5 5 5
MEDORA 15.0 18.0 20.0 : 5 5 5 5 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 : 5 5 5 5 5 5
SPRING CREEK…..
ZAP 14.0 18.0 20.0 : 5 6 5 5 5 5
KNIFE RIVER…..
HAZEN 21.0 24.0 25.0 : 5 5 5 5 5 5
HEART RIVER…..
MANDAN 17.0 23.0 28.0 : 5 5 5 5 5 5
APPLE CREEK…..
MENOKEN 15.0 16.0 17.0 : 5 5 5 5 5 5
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 : 5 5 5 5 5 5
BEAVER CREEK…..
LINTON 9.0 11.0 13.0 : 5 5 5 5 5 5
JAMES RIVER…..
GRACE CITY 12.0 14.0 15.0 : 5 5 5 5 5 5
PIPESTEM CREEK…..
PINGREE 9.0 11.0 13.0 : 5 5 5 5 5 5
JAMES RIVER…..
LAMOURE 14.0 16.0 18.0 : 5 5 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 4.6 FEET AND ONLY A 10 PERCENT CHANCE THAT
IT WILL RISE ABOVE 7.3 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 4.6 4.6 4.6 4.6 5.5 7.3 8.7
LITTLE MISSOURI RIVER…..
MARMARTH 2.4 2.4 2.4 3.0 4.0 5.1 13.5
MEDORA 3.3 3.3 3.3 3.4 4.5 8.4 15.4
WATFORD CITY 1.5 1.5 1.5 1.5 1.6 7.3 13.1
KNIFE RIVER…..
MANNING 6.5 6.5 6.5 6.5 7.8 9.1 13.1
SPRING CREEK…..
ZAP 5.2 5.2 5.2 5.2 7.0 8.6 11.6
KNIFE RIVER…..
HAZEN 2.2 2.2 2.2 2.2 5.4 10.5 19.2
HEART RIVER…..
MANDAN 3.2 3.2 3.2 3.2 3.8 7.1 9.0
APPLE CREEK…..
MENOKEN 5.4 5.4 5.4 5.4 7.2 13.1 14.4
CANNONBALL RIVER…..
REGENT 5.0 5.0 5.3 6.1 6.5 7.1 7.4
CEDAR CREEK…..
RALEIGH 2.4 2.4 2.4 2.6 3.5 4.0 6.9
CANNONBALL RIVER…..
BREIEN 4.2 4.2 4.2 5.0 6.6 7.2 10.0
BEAVER CREEK…..
LINTON 4.6 4.6 4.6 4.6 5.9 6.2 7.0
JAMES RIVER…..
GRACE CITY 4.7 4.7 4.7 4.7 4.7 4.8 5.4
PIPESTEM CREEK…..
PINGREE 5.1 5.1 5.1 5.1 5.1 5.3 5.8
JAMES RIVER…..
LAMOURE 7.8 7.8 7.8 7.8 7.8 7.9 8.2
…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 2009.
. 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 CLINK 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.
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PROBABILISTIC HYDROLOGIC OUTLOOK
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