547
FGUS73 KBIS 261727
ESFBIS
NDC009-013-023-049-069-075-079-101-270130-
PROBABILISTIC HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE BISMARCK ND
1127 AM CST THU FEB 26 2026
..SPRING FLOOD AND WATER RESOURCES OUTLOOK
THIS SPRING FLOOD AND WATER RESOURCES OUTLOOK IS FOR THE SOURIS
RIVER BASIN OF NORTH DAKOTA, COVERING THE PERIOD OF 02 MARCH
THROUGH 31 MAY, 2026. THIS OUTLOOK IS THE SECOND OF THREE IN A SERIES
OF OUTLOOKS THAT THE NATIONAL WEATHER SERVICE COLLECTIVELY REFERS TO
AS THE SPRING FLOOD AND WATER RESOURCES OUTLOOKS. THIS WILL BE
FOLLOWED BY SPRING FLOOD AND WATER RESOURCES OUTLOOKS TO BE ISSUED
ON 26 FEBRUARY, AND 12 MARCH, 2026. ON MARCH 26TH, THE NATIONAL
WEATHER SERVICE WILL REVERT BACK TO ITS NORMAL ISSUANCE OF THE
90-DAY PROBABILISTIC OUTLOOKS, USUALLY ON, OR ABOUT THE 4TH THURSDAY
OF EVERY MONTH.
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 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
RECENT AIRBORNE SNOW SURVEYS HAVE REVEALED MORE THAN EXPECTED
AMOUNTS OF SNOW-WATER EQUIVALENT (SWE) IN THE SOURIS RIVER BASIN OF
NORTH DAKOTA. IN SHORT, THE VISUAL LOSS OF SNOW DURING RECENT WARM
WEATHER IS DECEPTIVE. WIDESPREAD TWO TO ALMOST THREE INCHES OF SWE
REMAINS ACROSS MUCH OF THE SOURIS RIVER BASIN OF NORTH DAKOTA, WITH
UP TO A LITTLE OVER FOUR INCHES OF SWE IN THE TURTLE MOUNTAIN AREA.
FOR SURE, SOME OF THIS SWE IS NOW TRAPPED IN THE UPPER FEW INCHES OF
THE LOCAL SOILS. WHILE THIS WATER IS NOT READILY AVAILABLE TO RUN
OFF INTO THE LOCAL STREAMS, IT HAS CREATED A NEARLY IMPERMEABLE
GROUND SURFACE WHICH WILL ENHANCE RUNOFF FROM ANY MELTING SNOW OR
EARLY SPRING RAINS.
THIS NEW DATA RAISES THE RISK OF FLOODING AT SOME LOCATIONS TO NEAR,
OR ABOVE NORMAL RISK LEVELS. THE KEY HERE IS THAT THE SOILS ARE NOW
WIDELY WET AND FROZEN EVEN AS THE SWE SITTING ON THE GROUND IS NOT
ALARMING IN AND OF ITSELF. THE AREA WITH THE HIGHEST SWE IS IN AND
AROUND THE TURTLE MOUNTAIN AREA, BUT SINCE IT HAS NOT YET
EXPERIENCED SIGNIFICANT MELTING OF ITS SNOWPACK, THE SOILS UNDER THE
SNOW ARE NOT LIKELY AS IMPERMEABLE AS THE WESTERN AND SOUTHERN PARTS
OF THE BASIN.
IN GENERAL, THE RISK OF FLOODING AT FORECAST POINTS FROM THE SOURIS
RIVER NEAR SHERWOOD ON DOWN THROUGH MINOT AND OVER TO VELVA REMAIN
SOMEWHAT BELOW NORMAL TO NEAR NORMAL. HOWEVER, FROM THE SOURIS
RIVER NEAR TOWNER ON UP THROUGH WESTHOPE, FLOOD RISK IS ELEVATED.
THIS ELEVATED FLOOD RISK ALSO INCLUDES THE WINTERING RIVER AND
WILLOW CREEK WATERSHEDS.
LOOKING AT EXPECTATIONS FOR WEATHER GOING INTO EARLY MARCH, IT IS
LIKELY THAT WARM WEATHER IN EARLY MARCH WILL FURTHER ERODE THE
SNOWPACK...ESPECIALLY IN THE SOUTHERN AND WESTERN PARTS OF THE
BASIN. HOWEVER, THE EXTENT TO WHICH THIS WILL OCCUR, OR HOW MUCH
RUNOFF MAY BE GENERATED IS HIGHLY SPECULATIVE AT THIS POINT BECAUSE
IT IS NOT LIKELY THAT THIS WILL BE OF A LONG ENOUGH DURATION TO SEE
THE MELT AND RUNOFF TO CONCLUSION.
..SNOWPACK CONDITIONS
THE SNOW ACCUMULATION SEASON STARTED OUT WITH AN ABOVE NORMAL AMOUNT
OF SNOW AND ITS ACCOMPANYING SNOW-WATER EQUIVALENT (SWE) IN EARLY
DECEMBER. HOWEVER, A FAIRLY WARM STRETCH IN EARLY JANUARY MELTED
MUCH OF THE EARLY SNOWPACK, ESPECIALLY IN THE SOUTHERN AND WESTERN
PORTION OF THE SOURIS RIVER BASIN OF NORTH DAKOTA. WHILE THERE WAS
SURELY SOME SWE LOST TO EVAPORATION AND SUBLIMATION, MUCH OF THE
MELTWATER REMAINS IN THE BASIN IN THE FORM OF ICE ON THE GROUND, OR
IT INFILTRATED INTO THE GROUND BEFORE REFREEZING AS SOIL MOISTURE.
RECENT AIRBORNE SURVEYS PAINT A MUCH WETTER PICTURE THAN PREVIOUSLY
BELIEVED WITH NEARLY ALL OF THE CENTRAL PORTION OF THE SOURIS RIVER
BASIN OF NORTH DAKOTA WITH TWO TO ALMOST THREE INCHES OF SWE SITTING
ON THE GROUND, OR IN THE UPPER FEW INCHES OF THE LOCAL SOILS. SWE
VALUES IN THE TURTLE MOUNTAIN AREA ARE HIGHER, WITH FOUR PLUS INCHES
LIKELY.
..CURRENT DROUGHT CONDITIONS
THERE ARE NO DROUGHT DESIGNATIONS WITHIN THE SOURIS RIVER BASIN OF
NORTH DAKOTA.
..RESERVOIRS AND NATURAL WETLANDS
RESERVOIRS AND NATURAL WETLANDS ARE GENERALLY WELL WITHIN THE NORMAL
RANGE OF THEIR LONG-TERM TRENDS FOR THIS TIME OF YEAR. ALL FLOOD
CONTROL PROJECTS ARE AT, OR BELOW, THEIR DESIRED WINTER LEVELS IN
PREPARATION FOR THE SPRING MELT SEASON.
..SOIL CONDITIONS
AGAIN, DUE TO THE WIDESPREAD MELTING OF THE SNOWPACK OVER MUCH OF
THE SOURIS RIVER BASIN OF NORTH DAKOTA, NEAR SURFACE SOIL MOISTURE
TENDS TO BE VERY HIGH. THE UPPER 4 INCHES OF THE SOIL PROFILE TENDS
TO BE AROUND THE 95TH PERCENTILE FOR THE VAST MAJORITY OF THE BASIN,
WITH ONLY THE TURTLE MOUNTAIN AREA BEING MUCH MORE NORMAL AS IT
EXPERIENCED THE LEAST AMOUNT OF EARLY JANUARY MELT. SOIL
TEMPERATURES ALSO VARY CONSIDERABLY ACROSS THE BASIN WITH AREAS
HAVING LITTLE SNOW TO INSULATE THE GROUND SHOWING BELOW FREEZING
TEMPERATURES DOWN TO AS MUCH AS 39 INCHES, WHILE AREAS HAVING BEEN
CONSISTENTLY COVERED WITH SNOW SINCE EARLY DECEMBER HAVING FREEZING
TEMPERATURES DOWN TO AROUND 20-31 INCHES.
IN SHORT, THE SOILS ALL ACROSS THE BASIN ARE WET, FROZEN, AND WELL
CAPABLE OF ENHANCING OBSERVED RUNOFF FROM A GIVEN SNOWPACK OR EARLY
SPRING RAIN EVENT. OR, IN THE MORE EXTREME OF CASES FOR A SPRING
MELT, A WARM RAIN EVENT ON TOP OF AN ALREADY MELTING SNOWPACK.
WEATHER OUTLOOK...
THE NEAR-TERM 6-10 AND 8-14 DAY WEATHER OUTLOOKS FAVOR ABOVE
NORMAL TEMPERATURES AND ABOVE NORMAL PRECIPITATION. THE ONE-MONTH
OUTLOOKS FOR THE MONTH OF MARCH SLIGHTLY FAVORS BELOW NORMAL
TEMPERATURES FOR THE SOURIS RIVER BASIN OF NORTH DAKOTA, BUT HAS THE
AREA IN THE EQUAL CHANCES CATEGORY FOR BELOW NORMAL, NEAR NORMAL, OR
ABOVE NORMAL PRECIPITATION.
LOOKING EVEN LONGER TERM, THE 3-MONTH OUTLOOKS COVERING MARCH,
APRIL, AND MAY SLIGHTLY FAVORS BELOW NORMAL TEMPERATURES IN THE
EASTERN PART OF THE BASIN, WITH THE WESTERN PORTION IN THE EQUAL
CHANCES CATEGORY. PRECIPITATION IS ALSO IN THE EQUAL CHANCES
CATEGORY FOR BELOW NORMAL, NEAR NORMAL, OR ABOVE NORMAL
PRECIPITATION.
IN TABLE 1 BELOW, THE CURRENT (CS) AND HISTORICAL (HS) OR NORMAL
PROBABILITIES OF EXCEEDING MINOR...MODERATE...AND MAJOR FLOOD STAGE
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 GREATER 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: 02/16/2026 - 05/17/2026
: 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
FOXHOLM 1651.0 1653.0 1654.0 : <5 <5 <5 <5 <5 <5
:SOURIS
SHERWOOD 1623.0 1625.0 1630.0 : 17 11 <5 5 <5 <5
FOXHOLM 1573.0 1576.0 1578.0 : 42 36 23 16 <5 <5
MINOT 1562.0 1565.0 1570.0 : 11 16 6 6 <5 <5
MINOT 1551.0 1553.0 1557.0 : <5 <5 <5 <5 <5 <5
LOGAN 1536.0 1538.0 1540.0 : 23 19 <5 <5 <5 <5
SAWYER 1524.0 1526.0 1528.0 : 5 7 <5 <5 <5 <5
VELVA 1507.0 1512.0 1517.0 : 13 16 <5 <5 <5 <5
:WINTERING
KARLSRUHE 1509.0 1511.0 1512.0 : 12 14 <5 <5 <5 <5
:SOURIS
TOWNER 1454.0 1456.0 1458.0 : 89 55 37 28 <5 <5
BANTRY 1440.0 1441.0 1443.0 : 94 56 67 41 7 9
:WILLOW CREEK
WILLOW CITY 1442.0 1446.0 1448.0 : >95 47 52 20 12 6
:SOURIS
WESTHOPE 1414.0 1418.0 1420.0 : 80 53 12 23 <5 17
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: 02/16/2026 - 05/17/2026
LOCATION 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:DES LACS
FOXHOLM 1642.5 1642.7 1643.3 1645.2 1647.5 1649.0 1650.6
:SOURIS
SHERWOOD 1613.7 1614.6 1616.4 1618.1 1622.6 1623.4 1624.2
FOXHOLM 1570.6 1570.6 1570.7 1572.6 1575.8 1576.7 1577.1
MINOT 1554.5 1554.7 1554.9 1556.5 1559.9 1562.2 1566.2
MINOT 1543.1 1543.2 1543.4 1544.0 1545.1 1546.7 1550.5
LOGAN 1527.3 1527.6 1528.1 1530.0 1535.5 1537.2 1538.0
SAWYER 1512.8 1513.1 1514.1 1516.8 1521.5 1523.0 1524.4
VELVA 1497.0 1497.2 1498.8 1502.6 1506.3 1507.5 1508.8
:WINTERING
KARLSRUHE 1506.8 1506.9 1507.4 1507.9 1508.6 1509.2 1509.3
:SOURIS
TOWNER 1453.6 1454.0 1454.6 1455.6 1456.5 1457.0 1457.5
BANTRY 1439.8 1440.2 1440.8 1441.5 1442.2 1442.7 1443.3
:WILLOW CREEK
WILLOW CITY 1444.0 1444.2 1445.2 1446.0 1447.1 1448.4 1448.8
:SOURIS
WESTHOPE 1413.2 1413.5 1414.2 1415.6 1417.3 1418.1 1419.5
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:
LOCATION 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:DES LACS
FOXHOLM 0.0 0.0 0.0 0.0 0.0 0.0 0.0
:SOURIS
SHERWOOD 0.0 0.0 0.0 0.0 0.0 0.0 0.0
FOXHOLM 0.0 0.0 0.0 0.0 0.0 0.0 0.0
MINOT 0.0 0.0 0.0 0.0 0.0 0.0 0.0
MINOT 0.0 0.0 0.0 0.0 0.0 0.0 0.0
LOGAN 0.0 0.0 0.0 0.0 0.0 0.0 0.0
SAWYER 0.0 0.0 0.0 0.0 0.0 0.0 0.0
VELVA 0.0 0.0 0.0 0.0 0.0 0.0 0.0
:WINTERING
KARLSRUHE 0.0 0.0 0.0 0.0 0.0 0.0 0.0
:SOURIS
TOWNER 0.0 0.0 0.0 0.0 0.0 0.0 0.0
BANTRY 0.0 0.0 0.0 0.0 0.0 0.0 0.0
:WILLOW CREEK
WILLOW CITY 0.0 0.0 0.0 0.0 0.0 0.0 0.0
:SOURIS
WESTHOPE 0.1 0.1 0.1 0.1 0.0 0.0 0.0
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 12 MARCH.
SCHLAG
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