632  
FGUS73 KBIS 262045  
ESFBIS  
NDC009-013-023-049-061-069-075-079-101-302200-  
 
PROBABILISTIC HYDROLOGIC OUTLOOK  
NATIONAL WEATHER SERVICE BISMARCK ND  
340 PM CDT THU OCT 26 2017  
   
..FLOOD AND WATER RESOURCES OUTLOOK
 
 
THIS PROBABILITY BASED FLOOD AND WATER RESOURCES OUTLOOK IS  
FOR THE SOURIS (MOUSE) RIVER BASIN OF NORTH DAKOTA AND COVERS THE  
PERIOD OF LATE OCTOBER THROUGH LATE JANUARY, 2018.  
 
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  
FINDS THE REGION WITH LITTLE RISK OF WIDESPREAD RIVER FLOODING,  
WHICH IS NORMAL FOR THIS TIME OF YEAR.  
   
..CURRENT CONDITIONS
 
 
RESERVOIRS ARE ALREADY NEAR, OR BELOW WINTER DRAWDOWN LEVELS IN THE  
BASIN. RELATIVELY DRIER CONDITIONS OVER THE EARLY PART OF FALL HAVE  
ALSO LOWERED SOIL MOISTURE TO SLIGHTLY BELOW NORMAL LEVELS.  
SIMILARLY, MANY WETLANDS ACROSS THE REGION HAVE ALSO FALLEN TO BELOW  
THE LEVELS SEEN IN THE LAST FEW YEARS EVEN THOUGH MANY REMAIN ABOVE  
LONG-TERM HISTORICAL LEVELS.  
   
..WEATHER OUTLOOK
 
 
THE CPC OUTLOOKS PRETTY ARE PRETTY CONSISTENT GOING INTO  
NOVEMBER WITH A WELL ABOVE NORMAL CHANCE FOR BELOW NORMAL  
TEMPERATURES AND ABOVE NORMAL PRECIPITATION. HOWEVER, THE ONE-MONTH  
GRAPHICS SUGGEST OVERALL UNCERTAINTY WITH NOVEMBER AS THE REGION  
IS GENERALLY IN THE EQUAL CHANCES CATEGORY FOR BOTH TEMPERATURE  
AND PRECIPITATION. SIMILARLY, THE THREE-MONTH OUTLOOK COVERING  
NOVEMBER THROUGH JANUARY IS FAIRLY NEUTRAL BUT THE WINTER OUTLOOK  
COVERING DECEMBER THROUGH FEBRUARY OUTLOOK SUGGESTS COOLER AND  
WETTER THAN NORMAL.  
   
..IMPORTANT NOTE ON SUBSTANTIVE CHANGES
 
BEGINNING JANUARY 1ST OF  
2016, THE NATIONAL WEATHER SERVICE CONVERTED ALL RIVER GAGE DATA IN  
THE SOURIS RIVER BASIN OF NORTH DAKOTA TO FEET ABOVE MEAN SEA LEVEL  
USING THE NORTH AMERICAN VERTICAL DATUM OF 1988. THIS INCLUDED RAISES  
IN FLOOD STAGE DEFINITIONS BY UP TO ONE FOOT AT INDIVIDUAL LOCATIONS  
IN ORDER TO CONTINUE WORKING WITH WHOLE NUMBERS. MORE INFORMATION ON  
THIS CAN BE HAD BY CONTACTING SERVICE HYDROLOGIST ALLEN SCHLAG  
AT 701-250-4495.  
 
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 OF THE MODEL  
PREDICTING A RISE TO 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.  
 
   
..TABLE 1--PROBABILITIES FOR MINOR...MODERATE AND MAJOR FLOODING
 
 
VALID PERIOD: 10/29/2017 - 01/27/2018  
 
: 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  
-------- ----- ----- ----- : --- --- --- --- --- ---  
DES LACS RIVER  
FOXHOLM 1651.0 1653.0 1654.0 <5 <5 <5 <5 <5 <5  
SOURIS RIVER  
SHERWOOD 1623.0 1625.0 1630.0 <5 <5 <5 <5 <5 <5  
FOXHOLM 1573.0 1576.0 1578.0 <5 <5 <5 <5 <5 <5  
MINOT 4NW 1562.0 1565.0 1570.0 <5 <5 <5 <5 <5 <5  
MINOT BRWY BRDG 1551.0 1553.0 1557.0 <5 <5 <5 <5 <5 <5  
LOGAN 1536.0 1538.0 1540.0 <5 <5 <5 <5 <5 <5  
SAWYER 1524.0 1526.0 1528.0 <5 <5 <5 <5 <5 <5  
VELVA 1507.0 1512.0 1517.0 <5 <5 <5 <5 <5 <5  
WINTERING RIVER  
KARLSRUHE 1509.0 1511.0 1512.0 <5 <5 <5 <5 <5 <5  
SOURIS RIVER  
TOWNER 1454.0 1456.0 1458.0 <5 <5 <5 <5 <5 <5  
BANTRY 1440.0 1441.0 1443.0 <5 <5 <5 <5 <5 <5  
WILLOW CREEK  
WILLOW CITY 1442.0 1446.0 1448.0 <5 5 <5 <5 <5 <5  
SOURIS RIVER  
WESTHOPE 1414.0 1418.0 1420.0 <5 <5 <5 <5 <5 <5  
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: 10/29/2017 - 01/27/2018  
LOCATION 95% 90% 75% 50% 25% 10% 5%  
-------- ------ ------ ------ ------ ------ ------ ------  
DES LACS RIVER  
FOXHOLM 1639.3 1639.3 1639.3 1639.3 1639.5 1639.8 1640.1  
SOURIS RIVER  
SHERWOOD 1607.6 1607.9 1608.3 1608.4 1608.6 1608.7 1608.7  
FOXHOLM 1566.5 1566.5 1566.5 1566.5 1566.5 1566.5 1566.5  
MINOT 4NW 1551.0 1551.0 1551.0 1551.0 1551.0 1551.2 1551.3  
MINOT BRWY BRDG 1537.9 1537.9 1537.9 1537.9 1538.3 1538.8 1539.4  
LOGAN 1520.0 1520.0 1520.0 1520.0 1520.1 1520.3 1520.9  
SAWYER 1506.7 1506.7 1506.7 1506.7 1507.2 1507.7 1507.9  
VELVA 1490.2 1490.2 1490.2 1490.2 1490.5 1491.3 1491.6  
WINTERING RIVER  
KARLSRUHE 1502.8 1502.8 1502.8 1502.8 1502.8 1503.3 1503.8  
SOURIS RIVER  
TOWNER 1445.7 1445.7 1445.7 1445.7 1445.7 1445.7 1445.8  
BANTRY 1431.9 1431.9 1431.9 1431.9 1431.9 1431.9 1431.9  
WILLOW CREEK  
WILLOW CITY 1436.0 1436.0 1436.0 1436.0 1436.0 1436.3 1436.6  
SOURIS RIVER  
WESTHOPE 1409.8 1409.8 1409.8 1409.8 1409.8 1409.8 1410.1  
 
   
..TABLE 3--NONEXCEEDANCE PROBABILITIES
 
 
CHANCE OF FALLING BELOW STAGES  
AT SPECIFIC LOCATIONS  
VALID PERIOD: 10/29/2017 - 01/27/2018  
LOCATION 95% 90% 75% 50% 25% 10% 5%  
-------- ------ ------ ------ ------ ------ ------ ------  
DES LACS RIVER  
FOXHOLM 1639.2 1639.1 1639.0 1639.0 1639.0 1639.0 1639.0  
SOURIS RIVER  
SHERWOOD 1605.5 1605.5 1605.5 1605.5 1605.5 1605.5 1605.5  
FOXHOLM 1566.5 1566.5 1566.5 1566.5 1566.5 1566.5 1566.5  
MINOT 4NW 1550.9 1550.9 1550.8 1550.7 1550.7 1550.7 1550.7  
MINOT BRWY BRDG 1537.5 1537.3 1536.9 1536.7 1536.7 1536.7 1536.7  
LOGAN 1520.0 1519.9 1519.8 1519.8 1519.8 1519.8 1519.8  
SAWYER 1506.7 1506.7 1506.6 1506.6 1506.6 1506.6 1506.6  
VELVA 1490.2 1490.2 1490.2 1490.2 1490.2 1490.2 1490.2  
WINTERING RIVER  
KARLSRUHE 1502.8 1502.8 1502.8 1502.8 1502.8 1502.8 1502.8  
SOURIS RIVER  
TOWNER 1445.0 1444.9 1444.8 1444.8 1444.8 1444.8 1444.8  
BANTRY 1431.2 1431.1 1431.0 1431.0 1431.0 1431.0 1431.0  
WILLOW CREEK  
WILLOW CITY 1436.0 1436.0 1436.0 1436.0 1436.0 1436.0 1436.0  
SOURIS RIVER  
WESTHOPE 1409.4 1409.4 1409.4 1409.4 1409.4 1409.4 1409.4  
 
THESE LONG-RANGE PROBABILISTIC OUTLOOKS CONTAIN FORECAST VALUES THAT  
ARE CALCULATED USING HISTORICAL CONDITIONS FROM 30 OR MORE YEARS OF  
CLIMATOLOGICAL DATA...AND 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 NEAR THE END OF NEXT MONTH.  
 

 
AJS  
 
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