PROBABILISTIC HYDROLOGIC OUTLOOK
 NATIONAL WEATHER SERVICE BISMARCK ND

…FLOOD OUTLOOK OVERVIEW HIGHLIGHTS…

OVERALL THE FLOOD RISK ACROSS THE MISSOURI AND JAMES RIVER BASINS

REMAINS NEAR NORMAL TO SOMEWHAT ELEVATED. DESPITE RECENT YEARS WHERE

THE GREATEST CONTRIBUTOR TO FLOOD RISK WAS READILY APPARENT IN THE

SNOWPACK ON THE GROUND…THIS YEAR THE RISK COMES PRIMARILY FROM THE

FROZEN WET SOILS ACROSS SOUTHERN AND WESTERN NORTH DAKOTA AND THE

POSSIBILITY OF SPRING RAINS ON THOSE NEARLY IMPERMEABLE SOILS. THE

ONE RIVER WITH A GREATER THAN NORMAL RISK OF MINOR FLOODING NOT DUE

PRIMARILY TO THE SOIL CONDITIONS IS THE LITTLE MISSOURI RIVER WHICH

HAS AN ABOVE NORMAL SNOWPACK IN ITS HEADWATERS.

 

…CURRENT CONDITIONS…

SOIL MOISTURE AND FROST DEPTH ARE HIGHLY UNUSUAL ACROSS MOST OF

NORTH DAKOTA THIS YEAR. AN UNUSUALLY WET FALL AND EARLY COLD WEATHER

COMBINED TO CREATE DEEP FROST AND NEARLY IMPERMEABLE SOILS OVER

LARGE AREAS. NATIONAL WEATHER SERVICE SITES ARE RECORDING 49 INCHES

OF FROST IN THE BISMARCK AREA TO OVER 57 INCHES IN THE WILLISTON

AREA. OTHER RELIABLE REPORTS OF FROZEN WATER LINES AT DEPTHS OF 6.5

FEET SUGGEST THESE DEEPER FROST DEPTHS ARE NOT ISOLATED AND

REPRESENT A GREAT PORTION OF NORTH DAKOTA. RIVERS GENERALLY WENT

INTO WINTER ON THE HIGH RANGE OF NORMAL FOR WATER LEVELS. THIS HAS

RESULTED IN GREATER THAN NORMAL VOLUMES OF ICE IN THE RIVERS AND

STREAMS. SNOWPACK AND MOST IMPORTANTLY…ITS WATER CONTENT…IS

GENERALLY BELOW NORMAL ACROSS MOST OF SOUTHERN AND WESTERN NORTH

DAKOTA. SMALL AREAS OF OVER 2 INCHES OF WATER EQUIVALENT ARE PRESENT

IN THE APPLE CREEK…BEAVER CREEK…AND UPPER JAMES RIVER BASIN. THE

REST OF THE REGION IS GENERALLY AROUND AN INCH OR LESS OF WATER

EQUIVALENT ON AVERAGE.

 

…WEATHER OUTLOOK…

OVER THE COMING WEEKEND AND INTO EARLY NEXT WEEK…MUCH OF SOUTHERN

AND WESTERN NORTH DAKOTA ARE GOING TO EXPERIENCE TEMPERATURES WELL

ABOVE FREEZING FOR DAYTIME HIGHS AND OVERNIGHT LOWS RIGHT AROUND

FREEZING. THESE WARMER TEMPERATURES ARE EXPECTED TO MODERATE BY THE

MIDDLE OF NEXT WEEK. THERE IS NO EXPECTATION OF SIGNIFICANT

PRECIPITATION OVER THE NEXT WEEK ALTHOUGH MODEST AMOUNTS ARE

POSSIBLE. IN THE LONGER TERM ONE MONTH OUTLOOKS…THE REGION IS

FAVORED FOR BELOW NORMAL TEMPERATURES AND BELOW NORMAL

PRECIPITATION. AS ONE LOOKS EVEN LONGER TERM AT THE THREE MONTH

OUTLOOKS…BELOW NORMAL TEMPERATURES ARE STILL FAVORED WITH AN EQUAL

CHANCE OF BELOW NORMAL…NORMAL…OR ABOVE NORMAL PRECIPITATION.

 

…SUMMARY OF HYDROLOGIC CONDITIONS…

RIVERS ARE GENERALLY COVERED IN A THICKER THAN NORMAL…AND STILL

COMPETENT SHEET OF ICE. ALL DAMS HAVE THEIR FULL FLOOD CONTROL

STORAGE AVAILABLE TO THEM EVEN THOUGH SOME…SUCH AS DICKINSON DAM

AND HEART BUTTE DAM…ARE NOTABLY ABOVE THEIR AVERAGE RESERVOIR

ELEVATION FOR THIS TIME OF YEAR.

 

…NEAR TERM EXPECTATIONS FOR 8 MARCH TO 12 MARCH…TEMPERATURES

ABOVE FREEZING…EVEN FOR ONLY TWO TO FOUR DAYS…WILL KICK OFF THE

SPRING MELT THIS WEEKEND IN AREAS WITH RELATIVELY THIN SNOWCOVER.

AREAS WITH THICKER SNOW COVER WILL RESIST THE MELT FOR THE FIRST

NICE DAY OR TWO BEFORE PRODUCING APPRECIABLE RUNOFF…IN PARTICULAR

THE NORTHERN JAMES RIVER BASIN IS MOST LIKELY TO RESIST THE EARLY

EFFECTS OF THE WARM WEATHER AS THE THICKER SNOWPACK WILL TAKE MORE

TIME TO WARM…RIPEN…AND MELT. OVERALL…RIVERS AND STREAMS ACROSS

THE REGION ARE STILL HOLDING AN ABOVE NORMAL VOLUME OF ICE. EVEN AS

MANY LOCATIONS ARE EXPECTED TO START RECEIVING SNOWMELT RUNOFF…THE

RUNOFF VOLUMES ARE NOT LIKELY GOING TO BE ENOUGH TO WARRANT UNDUE

CONCERNS OF ICE JAM RELATED FLOODING IN THE SHORT TERM. THE MOST

LIKELY OUTCOME WILL BE INSTREAM RISES WHICH CAN MAKE ICE MORE

HAZARDOUS FOR RECREATIONAL USERS AS OPPOSED TO LIFTING…BREAKING…

AND MOBILIZING THE ICE WHICH ENHANCES RISKS FOR ICE JAM FLOODING.

 

…FIRST LOOK AT MISSOURI RIVER RUNOFF…

SNOWPACK ON THE PLAINS OF MONTANA AND NORTH DAKOTA THAT CONTRIBUTE

TO THE MISSOURI RIVER IS NOT GOING TO SIGNIFICANTLY CONTRIBUTE TO

MISSOURI RIVER FLOWS THIS YEAR. RUNOFF FROM SPRING RAINS IS STILL A

WILDCARD AT THIS POINT OF THE YEAR…BUT THERE IS NO REASON TO

EXPECT THE NEAR RECORD TO RECORD SPRING RAINS THAT CONTRIBUTED TO

THE MISSOURI RIVER PROBLEMS IN 2011. MOUNTAIN SNOWPACK IS WELL ABOVE

NORMAL IN THE UPPER YELLOWSTONE AND MISSOURI RIVER HEADWATERS. THIS

ABOVE NORMAL SNOWPACK SUGGESTS A GOOD YEAR FOR RUNOFF IN THE

MISSOURI RIVER OVERALL…BUT STILL WELL BELOW WHAT WOULD BE NEEDED

TO CREATE SIGNIFICANT PROBLEMS.

 

 

…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 3/8/2014 TO 6/6/2014 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 : 72 50 39 25 5 11

LITTLE MISSOURI RIVER…..

MARMARTH 18.0 23.0 30.0 : 16 5 5 5 5 5

MEDORA 15.0 18.0 20.0 : 20 7 17 5 16 5

WATFORD CITY 20.0 24.0 30.0 : 5 5 5 5 5 5

KNIFE RIVER…..

MANNING 15.0 17.0 20.0 : 17 17 5 5 5 5

SPRING CREEK…..

ZAP 14.0 18.0 20.0 : 25 22 9 6 6 5

KNIFE RIVER…..

HAZEN 21.0 24.0 25.0 : 35 28 15 11 12 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 : 58 57 44 48 7 26

CANNONBALL RIVER…..

REGENT 22.0 24.0 26.0 : 5 5 5 5 5 5

CEDAR CREEK…..

RALEIGH 12.0 14.0 16.0 : 19 5 6 5 5 5

CANNONBALL RIVER…..

BREIEN 10.0 20.0 23.0 : 98 48 11 5 5 5

BEAVER CREEK…..

LINTON 9.0 11.0 13.0 : 31 37 14 28 8 12

JAMES RIVER…..

GRACE CITY 12.0 14.0 15.0 : 5 9 5 6 5 5

PIPESTEM CREEK…..

PINGREE 11.0 13.0 15.0 : 7 5 5 5 5 5

JAMES RIVER…..

LAMOURE 14.0 16.0 18.0 : 11 10 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 8.2 FEET AND ONLY A 10 PERCENT CHANCE THAT

IT WILL RISE ABOVE 13.2 FEET.

 

 

JAMES AND MISSOURI RIVER BASINS

LONG-RANGE PROBABILISTIC OUTLOOK

PROBABILITIES FOR EXCEEDING LISTED RIVER STAGES

FROM 3/8/2014 TO 6/6/2014 Z

 

TABLE 2

 

LOCATION 95% 90% 75% 50% 25% 10% 05%

——– —— —— —— —— —— —— ——

LITTLE MUDDY CREEK…..

WILLISTON 8.2 8.8 9.9 11.3 12.3 13.2 13.7

LITTLE MISSOURI RIVER…..

MARMARTH 5.6 5.8 7.4 11.1 14.3 19.4 20.3

MEDORA 6.8 7.1 8.5 11.9 14.3 20.9 21.4

WATFORD CITY 3.7 3.8 5.5 8.3 10.3 17.3 17.8

KNIFE RIVER…..

MANNING 7.4 7.7 9.1 11.2 14.2 15.7 16.3

SPRING CREEK…..

ZAP 5.0 5.7 7.5 10.5 14.3 17.8 21.2

KNIFE RIVER…..

HAZEN 3.9 4.7 9.0 15.6 22.2 25.3 26.1

HEART RIVER…..

MANDAN 2.7 2.9 4.2 7.7 11.8 14.8 16.7

APPLE CREEK…..

MENOKEN 9.6 9.9 12.3 15.7 16.4 16.7 17.4

CANNONBALL RIVER…..

REGENT 6.0 6.1 7.9 9.0 12.2 15.3 16.6

CEDAR CREEK…..

RALEIGH 8.2 8.4 9.1 10.1 11.5 13.1 14.1

CANNONBALL RIVER…..

BREIEN 11.6 12.3 13.5 14.9 16.6 20.2 20.6

BEAVER CREEK…..

LINTON 5.7 5.7 6.3 7.4 9.4 12.1 15.1

JAMES RIVER…..

GRACE CITY 5.3 5.5 6.1 6.8 8.2 10.4 11.6

PIPESTEM CREEK…..

PINGREE 5.9 6.0 7.0 8.1 9.8 10.5 11.3

JAMES RIVER…..

LAMOURE 7.8 7.9 8.1 8.7 9.7 14.4 16.1

 

 

…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.