261  
FGUS73 KBIS 151843  
ESFBIS  
 
PROBABILISTIC HYDROLOGIC OUTLOOK  
NATIONAL WEATHER SERVICE BISMARCK ND  
937 AM CST THU FEB 15 2018  
 
   
..SPRING FLOOD AND WATER RESOURCES OUTLOOK
 
 
THIS PROBABILISTIC FLOOD AND WATER RESOURCES OUTLOOK IS FOR  
THE MISSOURI AND JAMES RIVER BASINS OF NORTH DAKOTA AND COVERS  
THE PERIOD OF MID-FEBRUARY THROUGH MID-MAY.  
 
THE FOLLOWING MESSAGE HAS FOUR SECTIONS. THE FIRST PROVIDES SOME  
TEXT ON THE HIGHLIGHTS OF THIS OUTLOOK AND CONDITIONS AFFECTING  
THE LOCAL HYDROLOGY. THE SECOND SECTION GIVES THE CURRENT AND  
NORMAL/HISTORICAL RISKS OF FLOODING AS DETERMINED BY THE ENSEMBLE  
STREAMFLOW FORECAST MODEL OF THE NATIONAL WEATHER SERVICE. THE  
THIRD SECTION GIVES THE CURRENT PROBABILITIES FOR REACHING FLOOD  
STAGE AT THE LISTED FORECAST LOCATIONS. AND FINALLY, THE FOURTH  
SECTION COVERS THE RISK OF THE RIVER SITES FALLING BELOW THE  
LISTED STAGES.  
   
..FLOOD OUTLOOK HIGHLIGHTS
 
 
THIS ISSUANCE OF THE MONTHLY PROBABILISTIC HYDROLOGIC OUTLOOK  
PROVIDES AN EARLY LOOK AT THE SPRING MELT SEASON. DUE TO BELOW  
NORMAL SNOWFALL, DRY SOILS, AND MORE AVAILABLE SPACE IN NATIVE  
WETLANDS, THE RISK OF WIDESPREAD FLOODING THIS SPRING IS WELL BELOW  
NORMAL. WHILE THE SPRING MELT SEASON IS STILL TOO FAR IN THE  
FUTURE TO RULE OUT AT LEAST SOME FLOODING, IT WOULD TAKE WELL ABOVE  
NORMAL PRECIPITATION GOING FORWARD TO BRING THE RISK UP TO  
HISTORICALLY NORMAL LEVELS. AT THIS POINT, THE MOISTURE DEFICITS OF  
LAST SUMMER AND FALL, AND THIS WINTER, ENHANCE THE RISK OF DROUGHT  
INTENSIFICATION ONCE WE GET PAST THE SPRING MELT SEASON. SO WHILE IT  
IS STILL A LITTLE EARLY FOR SPRING PROGNOSTICATIONS, THE RISKS SEEM  
TO BE TILTED MORE IN FAVOR OF A LACK OF NORMAL SPRING RUNOFF THAN OF  
WIDESPREAD FLOODING.  
 
ONE OF THE THINGS NOT INCLUDED IN THE BELOW TABLE IS THE RUNOFF FOR  
THE MISSOURI AND YELLOWSTONE RIVERS. WHILE WE ARE ABOUT HALF THROUGH  
THE SNOW ACCUMULATION SEASON FOR THE MOUNTAINS, IT IS ACTUALLY ABOVE  
NORMAL IN THE HEADWATERS FOR BOTH THE YELLOWSTONE AND MISSOURI RIVER  
BASINS. HOWEVER, THIS ALONE DOES NOT SUGGEST A TROUBLESOME RUNOFF  
EVENT AS PREVIOUS HIGH RUNOFF YEARS INCLUDED SIGNIFICANT SPRING RAINS  
ON THE PLAINS OF MONTANA AND NORTH DAKOTA.  
 
HIGH WATER DUE TO ICE JAMS IS ALSO NOT INCLUDED IN THE BELOW TABLES.  
HOWEVER, THE LACK OF A SIGNIFICANT SNOWPACK SUGGESTS SMALL RIVERS OF  
WESTERN AND CENTRAL NORTH DAKOTA WILL HAVE TROUBLE GENERATING ENOUGH  
RUNOFF TO LIFT AND MOBILIZE THE ICE. TO CREATE ICE PROBLEMS WOULD  
REQUIRE SIGNIFICANT, AND EARLY, SPRING RAINS.  
   
..CURRENT CONDITIONS
 
 
RIVERS, LAKES, AND RESERVOIRS ARE NEAR TO SLIGHTLY BELOW NORMAL  
FOR THIS TIME OF THE YEAR. MOST OF NORTH DAKOTA REMAINS WELL BELOW  
NORMAL FOR SNOW COVER WITH NEAR ZERO WATER EQUIVALENT IN THE  
SOUTHERNMOST TIER OF COUNTIES TO A WIDESPREAD 0.25 - 0.5 INCHES OF  
WATER ACROSS MOST OF CENTRAL AND WESTERN NORTH DAKOTA. THE HEAVIEST  
SNOWPACK IS IN THE UPPER JAMES RIVER BASIN, AND THAT IS STILL BELOW  
NORMAL AT ABOUT AN INCH OF WATER. SOIL MOISTURE LEVELS ARE ALSO WELL  
BELOW NORMAL ACROSS MOST OF THE STATE. SIMILARLY, WETLANDS TEND TO  
BE DOWN FROM THE RECENT HIGHS OF THE PAST SEVERAL YEARS. WESTERN AND  
CENTRAL PARTS OF THE STATE ARE CURRENTLY UNDER MODERATE TO SEVERE  
DROUGHT DESIGNATIONS, MOSTLY DUE TO THE DRY SUMMER AND FALL.  
   
..WEATHER OUTLOOK
 
THE NEAR TERM 6-10 AND 8-14 DAY GENERALLY  
FAVOR A COOLER THAN NORMAL PATTERN WITH NEAR NORMAL PRECIPITATION.  
THIS TILT TOWARDS COOLER THAN NORMAL TEMPERATURES CONTINUES THROUGH  
THE ONE-MONTH OUTLOOK WITH A SLIGHT FAVORING OF ABOVE NORMAL  
PRECIPITATION FOR WESTERN NORTH DAKOTA, AND NEAR NORMAL PRECIPITATION  
FOR THE REST OF THE STATE. LOOKING LONGER TERM AT THE THREE-MONTH  
OUTLOOK AND WE SEE A SLIGHT FAVORING OF BELOW NORMAL TEMPERATURES  
IN THE WESTERN HALF OF NORTH DAKOTA WITH AN OVERALL SLIGHTLY  
ENHANCED CHANCE FOR ABOVE NORMAL PRECIPITATION.  
 
IN TABLE 1 BELOW, THE CURRENT (CS) AND HISTORICAL (HS) OR NORMAL  
PROBABILITIES OF EXCEEDING MINOR, MODERATE, AND MAJOR FLOOD  
STAGES ARE LISTED FOR THE VALID TIME PERIOD.  
 
CS VALUES INDICATE THE PROBABILITY OF REACHING A FLOOD CATEGORY  
BASED ON CURRENT CONDITIONS.  
 
HS VALUES INDICATE THE PROBABILITY OF REACHING A FLOOD CATEGORY  
BASED ON HISTORICAL OR NORMAL CONDITIONS.  
 
WHEN THE VALUE OF CS IS MORE THAN HS, THE PROBABILITY OF  
EXCEEDING THAT LEVEL IS HIGHER THAN NORMAL. WHEN THE VALUE OF CS IS  
LESS THAN HS, THE PROBABILITY OF EXCEEDING THAT LEVEL IS LOWER  
THAN NORMAL.  
 
CHANCE OF EXCEEDING STAGES AT SPECIFIC LOCATIONS  
VALID PERIOD: 02/17/2018 - 05/18/2018  
 
: CURRENT AND HISTORICAL  
: CHANCES OF EXCEEDING  
: FLOOD CATEGORIES  
: AS A PERCENTAGE (%)  
CATEGORICAL :  
FLOOD STAGES (FT) : MINOR MODERATE MAJOR  
LOCATION MINOR MOD MAJOR : CS HS CS HS CS HS  
-------- ----- ----- ----- : --- --- --- --- --- ---  
:PIPESTEM CREEK  
PINGREE 11.0 13.0 15.0 : <5 12 <5 <5 <5 <5  
:JAMES RIVER  
GRACE CITY 12.0 14.0 15.0 : <5 15 <5 9 <5 7  
LAMOURE 14.0 16.0 18.0 : <5 9 <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 : 25 48 <5 <5 <5 <5  
:BEAVER CREEK  
LINTON 12.0 14.0 16.0 : 5 30 <5 7 <5 <5  
:LITTLE MUDDY RIVER  
WILLISTON 10.0 12.0 14.0 : <5 49 <5 27 <5 14  
:LITTLE MISSOURI  
MARMARTH 18.0 23.0 30.0 : <5 5 <5 <5 <5 <5  
:LITTLE MISSOURI RIVER  
MEDORA 15.0 18.0 20.0 : <5 7 <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 21 <5 <5 <5 <5  
:SPRING CREEK  
ZAP 14.0 18.0 20.0 : <5 24 <5 9 <5 6  
:KNIFE RIVER  
HAZEN 21.0 24.0 25.0 : <5 32 <5 18 <5 11  
:HEART RIVER  
MANDAN 17.0 23.0 28.0 : <5 9 <5 <5 <5 <5  
:APPLE CREEK  
MENOKEN 15.0 16.0 17.0 : 20 54 8 48 <5 28  
 
LEGEND  
CS = CONDITIONAL SIMULATION (CURRENT OUTLOOK)  
HS = HISTORICAL SIMULATION  
FT = FEET  
 
IN TABLE 2 BELOW, THE 95 THROUGH 5 PERCENT COLUMNS INDICATE THE  
PROBABILITY OF EXCEEDING THE LISTED STAGE LEVELS (FT) FOR THE VALID  
TIME PERIOD.  
   
..TABLE 2--EXCEEDANCE PROBABILITIES
 
 
CHANCE OF EXCEEDING STAGES  
AT SPECIFIC LOCATIONS  
VALID PERIOD: 02/17/2018 - 05/18/2018  
LOCATION 95% 90% 75% 50% 25% 10% 5%  
-------- ------ ------ ------ ------ ------ ------ ------  
:PIPESTEM CREEK  
PINGREE 4.9 4.9 5.0 5.3 5.8 7.8 9.1  
:JAMES RIVER  
GRACE CITY 4.2 4.3 4.5 4.9 6.1 7.2 8.4  
LAMOURE 6.7 6.7 6.9 7.2 7.5 8.2 9.4  
:CANNONBALL RIVER  
REGENT 5.0 5.3 6.1 6.7 7.7 8.8 9.4  
:CEDAR CREEK  
RALEIGH 1.1 1.8 3.4 4.7 6.2 7.3 8.0  
:CANNONBALL RIVER  
BREIEN 3.0 3.4 5.9 8.0 10.0 12.1 13.6  
:BEAVER CREEK  
LINTON 4.4 4.6 5.0 5.4 7.1 9.7 11.9  
:LITTLE MUDDY RIVER  
WILLISTON 4.5 4.5 4.5 5.2 6.3 8.2 8.8  
:LITTLE MISSOURI  
MARMARTH 2.0 2.5 3.4 4.2 5.9 9.6 13.6  
:LITTLE MISSOURI RIVER  
MEDORA 2.6 3.3 4.6 5.6 7.1 9.2 13.9  
WATFORD CITY 0.1 0.4 1.4 2.1 3.3 5.0 9.3  
:KNIFE RIVER  
MANNING 6.3 6.3 6.3 7.3 9.1 9.9 10.2  
:SPRING CREEK  
ZAP 5.0 5.0 5.3 6.5 9.0 11.0 12.3  
:KNIFE RIVER  
HAZEN 1.1 1.1 3.1 6.0 10.4 13.8 15.7  
:HEART RIVER  
MANDAN -0.1 0.2 1.8 3.0 4.9 6.8 9.4  
:APPLE CREEK  
MENOKEN 5.1 5.3 6.0 7.9 14.5 15.6 16.5  
 
IN TABLE 3 BELOW, THE 95 THROUGH 5 PERCENT COLUMNS INDICATE THE  
PROBABILITY OF FALLING BELOW THE LISTED STAGE LEVELS (FT) FOR THE  
VALID TIME PERIOD.  
   
..TABLE 3--NONEXCEEDANCE PROBABILITIES
 
 
CHANCE OF FALLING BELOW STAGES  
AT SPECIFIC LOCATIONS  
VALID PERIOD: 02/17/2018 - 05/18/2018  
LOCATION 95% 90% 75% 50% 25% 10% 5%  
-------- ------ ------ ------ ------ ------ ------ ------  
:PIPESTEM CREEK  
PINGREE 4.9 4.9 4.9 4.9 4.9 4.9 4.9  
:JAMES RIVER  
GRACE CITY 4.2 4.2 4.2 4.2 4.2 4.2 4.2  
LAMOURE 6.6 6.6 6.6 6.6 6.6 6.6 6.6  
:CANNONBALL RIVER  
REGENT 4.4 4.4 4.4 4.4 4.4 4.4 4.4  
:CEDAR CREEK  
RALEIGH 0.7 0.7 0.7 0.7 0.3 0.3 0.3  
:CANNONBALL RIVER  
BREIEN 2.4 2.4 2.4 2.4 2.4 2.4 2.4  
:BEAVER CREEK  
LINTON 4.3 4.3 4.3 4.3 4.3 4.2 4.2  
:LITTLE MUDDY RIVER  
WILLISTON 4.5 4.5 4.4 4.4 4.4 4.3 4.3  
:LITTLE MISSOURI  
MARMARTH 1.0 1.0 1.0 1.0 1.0 1.0 0.9  
:LITTLE MISSOURI RIVER  
MEDORA 1.4 1.4 1.4 1.4 1.4 1.4 1.3  
WATFORD CITY -0.6 -0.6 -0.6 -0.6 -0.6 -0.8 -1.0  
:KNIFE RIVER  
MANNING 6.3 6.3 6.3 6.3 6.3 5.9 5.5  
:SPRING CREEK  
ZAP 5.0 5.0 4.9 4.9 4.9 4.9 4.9  
:KNIFE RIVER  
HAZEN 1.1 1.1 1.1 1.1 1.0 0.9 0.9  
:HEART RIVER  
MANDAN -0.5 -0.5 -0.5 -0.5 -0.5 -0.7 -0.8  
:APPLE CREEK  
MENOKEN 4.2 4.2 4.2 4.2 4.2 4.1 4.0  
 
THESE LONG-RANGE PROBABILISTIC OUTLOOKS CONTAIN FORECAST VALUES THAT  
ARE CALCULATED USING MULTIPLE SEASON SCENARIOS FROM 30 OR MORE YEARS  
OF CLIMATOLOGICAL DATA, INCLUDING CURRENT CONDITIONS OF THE  
RIVER, SOIL MOISTURE, SNOW COVER, AND 30 TO 90 DAY LONG-RANGE  
OUTLOOKS OF TEMPERATURE AND PRECIPITATION. BY PROVIDING A 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.  
 
VISIT OUR WEB SITE WEATHER.GOV/BIS FOR MORE WEATHER AND WATER  
INFORMATION.  
 
THE NEXT OUTLOOK WILL BE ISSUED ON MARCH 1ST, 2018.  
 

 
 
AJS  
 
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