Spring Flood Outlook / Climate Review & Outlook

PROBABILISTIC HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE HASTINGS NE
341 AM CST THU JAN 27 2011

...SPRING FLOOD AND WATER RESOURCES OUTLOOK NUMBER 1...

THIS OUTLOOK IS FOR THE HASTINGS HYDROLOGIC SERVICE AREA /HSA/. IN
SOUTH CENTRAL NEBRASKA THIS OUTLOOK INCLUDES THE
PLATTE...LOUP...LITTLE BLUE...AND REPUBLICAN RIVERS AND THEIR
TRIBUTARIES. IN NORTH CENTRAL KANSAS...THE SOLOMON RIVER AND ITS
TRIBUTARIES ARE INCLUDED.

...SHORT TERM HYDROLOGIC OUTLOOK...JANUARY 27 TO FEBRUARY 17...

SIGNIFICANT SNOWMELT TODAY INTO FRIDAY MAY CAUSE FLOODING THAT COULD
LAST INTO THE WEEKEND OR EARLY NEXT WEEK ACROSS PORTIONS OF SOUTH
CENTRAL NEBRASKA.

A SOLID SNOWPACK OF 2 TO 8 INCHES REMAINS IN PLACE ACROSS MUCH OF
SOUTH CENTRAL NEBRASKA. IF YOU MELTED THIS SNOW DOWN...THE LIQUID
EQUIVALENT RANGES FROM AROUND 1 INCH TO 1.5 INCHES. HIGH
TEMPERATURES TODAY WILL CLIMB INTO THE 40S AND SOME AREAS
MAY EVEN APPROACH 50 DEGREES BY FRIDAY. THESE TEMPERATURES WILL
RESULT IN RAPID SNOWMELT.

FROST DEPTH MEASUREMENTS SHOW THAT THE GROUND IS FROZEN SOLID FROM
THE SURFACE TO A DEPTH OF 15 TO 25 INCHES. CONSEQUENTLY...SNOWMELT
RUNOFF WILL BE EXTENSIVE AS THE GROUND WILL NOT HAVE TIME TO THAW
AND WILL BE UNABLE TO QUICKLY ABSORB MUCH OF THE MOISTURE.

RIVER GAUGE SITES ALONG THE PLATTE...NORTH LOUP...AND LOUP RIVERS
SHOW THAT IN SOME AREAS THESE RIVERS ARE ALREADY RUNNING VERY
HIGH AND JUST BELOW FLOOD STAGE. CONSEQUENTLY...ANY ADDITIONAL
RUNOFF MAY QUICKLY PUSH THESE RIVERS INTO FLOOD. ICE JAMS HAVE
ALREADY CAUSED NUMEROUS PROBLEMS ALONG THE PLATTE RIVER AND MANY
OF THESE JAMS HAVE YET TO FULLY BREAK UP. THEREFORE...ADDITIONAL
RUNOFF COULD RENEW ICE JAM FLOODING ALONG PORTIONS OF THE PLATTE
RIVER. ALTHOUGH THERE HAVE BEEN NO SERIOUS ICE JAMS YET THIS
SEASON WITHIN THE LOUP RIVER BASIN...THIS BASIN IS AN ICE JAM
PRONE AREA. THEREFORE...WHEN THE ICE BEGINS TO BREAK UP THE NEXT
SEVERAL DAYS...ICE JAM FLOODING MAY ALSO OCCUR WITHIN THE LOUP RIVER
BASIN.

ALTHOUGH THE ICE WILL BEGIN TO BREAK UP THE NEXT FEW DAYS WITHIN THE
PLATTE AND LOUP RIVER BASINS...THE WARM UP WILL BE SHORT LIVED AND
SUBSTANTIAL ICE MAY POTENTIALLY REMAIN IN THESE RIVER SYSTEMS
THROUGH MUCH OF FEBRUARY. CONSEQUENTLY...THE THREAT OF OCCASIONAL
ICE JAM FLOODING WILL ALSO PERSIST IN THESE AREAS UNTIL MOST OF THE
ICE CAN MELT AWAY.

THE GREATEST THREAT FOR SNOWMELT RUNOFF FLOODING WILL BE WITHIN
THE PLATTE AND LOUP RIVER BASINS. HOWEVER...OTHER BASINS SUCH AS
THE LITTLE BLUE AND WEST FORK OF THE BIG BLUE WILL ALSO BE AT LEAST
SOMEWHAT SUSCEPTIBLE TO SNOW MELT FLOODING.

FURTHER SOUTH...THERE IS LITTLE TO NO SNOW REMAINING ACROSS THE
REPUBLICAN AND SOLOMON RIVER BASINS OF EXTREME SOUTH CENTRAL
NEBRASKA AND NORTH CENTRAL KANSAS. THEREFORE...SNOW MELT FLOODING IS
NOT EXPECTED OVER THESE AREAS.

...LONG TERM HYDROLOGIC OUTLOOK...MID FEBRUARY THROUGH APRIL...

SPRING FLOOD OUTLOOKS ARE ROUTINELY ISSUED FROM LATE JANUARY
THROUGH MARCH TO GIVE ADVANCED NOTICE OF POSSIBLE FLOODING.  THEY
ARE BASED ON SOIL MOISTURE...SNOWPACK MAGNITUDE...STREAMFLOW
CONDITIONS...AND THE LONG RANGE FORECAST OF FUTURE TEMPERATURE AND
PRECIPITATION PATTERNS.

THE FREQUENTLY BELOW NORMAL TEMPERATURES THIS PAST JANUARY HAVE
RESULTED IN ABNORMALLY THICK RIVER ICE WITHIN THE PLATTE AND LOUP
RIVER BASINS. IT MAY TAKE AWHILE FOR ALL OF THIS ICE TO MELT OFF AND
CONSEQUENTLY THE POTENTIAL OF ICE JAM FLOODING ISSUES ON THE
PLATTE...NORTH LOUP...MIDDLE LOUP...AND LOUP RIVERS MAY LINGER
THROUGH MUCH OF FEBRUARY.

THERE ARE SEVERAL FACTORS THAT CURRENTLY APPEAR FAVORABLE FOR SPRING
FLOODING AND SEVERAL OTHER FACTORS THAT WOULD BE UNFAVORABLE. ONE
FAVORABLE FACTOR IS THAT A MAJORITY OF STREAMS AND RIVERS ACROSS
SOUTH CENTRAL NEBRASKA AND FAR NORTH CENTRAL KANSAS HAVE BEEN
RUNNING AT ABOVE NORMAL STAGES. ANOTHER FAVORABLE FACTOR IS THE NEAR
NORMAL TO ABOVE NORMAL MOUNTAIN SNOWPACK OVER THE NORTH AND SOUTH
PLATTE RIVER BASINS WITH EARLY JANUARY SNOWPACK CURRENTLY RUNNING AT
90 TO 130 PERCENT OF AVERAGE. ADDITIONALLY THE LIQUID CONTENT IN OUR
CURRENT SNOWPACK IS RUNNING ABOVE NORMAL FOR THIS TIME OF YEAR
ACROSS THE PLATTE AND LOUP RIVER BASINS. HOWEVER...MUCH OF THIS SNOW
MAY MELT IN THE SHORT TERM...HAVING A LARGER IMPACT ON SHORT TERM
FLOOD POTENTIAL AND LESS IMPACT ON THE LONG TERM SPRING FLOOD
OUTLOOK.

SEVERAL FACTORS THAT WOULD SUGGEST A LESSER THREAT OF SPRING
FLOODING INCLUDE OUR CURRENT SOIL MOISTURE CONDITIONS AND LONG RANGE
FORECAST PROJECTIONS. SOIL CONDITIONS ARE ABNORMALLY DRY DUE LARGELY
IN PART TO AN ABNORMALLY DRY FALL. IN ADDITION...THE FEBRUARY
THROUGH APRIL LONG RANGE PRECIPITATION FORECAST IS INDICATING BETTER
ODDS AT SEEING DRIER THAN NORMAL CONDITIONS DUE TO THE CURRENT LA
NINA.

WHEN TAKING INTO CONSIDERATION ALL FACTORS...MOST RIVER GAUGING
SITES WILL SEE A NEAR NORMAL THREAT OF SPRING FLOODING.

...CLIMATOLOGICAL REVIEW...

TEMPERATURE WISE...THE MONTHS OF OCTOBER...NOVEMBER...DECEMBER AND
JANUARY HAVE BEEN A TALE OF CONTRASTS ACROSS SOUTH CENTRAL NEBRASKA
AND NORTH CENTRAL KANSAS...WITH THE AUTUMN MONTHS CHECKING IN WARMER
THAN AVERAGE...AND THE WINTER MONTHS COLDER THAN AVERAGE. BASED ON
30-YEAR AVERAGES FROM 1971-2000...READINGS ACROSS THE AREA IN
OCTOBER REGISTERED 2-4 DEGREES ABOVE AVERAGE...WHILE NOVEMBER
TEMPERATURES WERE 1-2 DEGREES ABOVE AVERAGE. A DOWNWARD TREND
STARTED IN DECEMBER...WITH TEMPERATURES GENERALLY ENDING UP
WITHIN 1 DEGREE EITHER SIDE OF AVERAGE. JANUARY THUS FAR HAS
FEATURED NOTABLY COLDER READINGS 3-6 DEGREES BELOW AVERAGE. DUE TO
THESE CONTRASTS LARGELY BALANCING EACH OTHER OUT...OVERALL AVERAGE
TEMPERATURES FOR THE LAST 4 MONTHS ARE GENERALLY WITHIN 1 DEGREE OF
NORMAL FOR MOST OF THE HASTINGS HSA. FOCUSING ON THE JANUARY
COLD...THE AVERAGE DAILY TEMPERATURE AT GRAND ISLAND THROUGH THE
25TH WAS ONLY 17.3 DEGREES...OR 4.8 DEGREES BELOW AVERAGE. THIS
RANKS AS THE 18TH-COLDEST FIRST 25 DAYS OF JANUARY...BASED ON 117
YEARS OF RECORDS DATING TO 1895.

PRECIPITATION WISE...THE MONTHS OF OCTOBER...NOVEMBER AND DECEMBER
FEATURED A PRONOUNCED DEFICIT COMPARED TO THE 30-YEAR AVERAGE...WITH
MOST OF THE HASTINGS HSA ONLY RECEIVING BETWEEN 0.75 AND 1.5 INCHES
DURING THIS TIME...OR GENERALLY 2 TO 2.5 INCHES BELOW AVERAGE FOR
THE 3-MONTH PERIOD AS A WHOLE. PUT ANOTHER WAY...MOST OF THE HSA
ONLY SAW 25-40 PERCENT OF NORMAL PRECIPITATION AMOUNTS FOR THIS
PERIOD. AT GRAND ISLAND...TOTAL PRECIPITATION FOR THESE 3 MONTHS
TOTALED ONLY 0.98 OF AN INCH...MARKING THE 11TH-DRIEST
OCTOBER-DECEMBER PERIOD ON RECORD DATING TO 1896...AND THE DRIEST
SINCE 1999. NOT SURPRISINGLY...BY THE END OF DECEMBER THE U.S.
DROUGHT MONITOR INDICATED ABNORMALLY DRY CONDITIONS ACROSS NEARLY
ALL OF SOUTH CENTRAL NEBRASKA AND NORTH CENTRAL KANSAS...AND A SMALL
AREA OF D1 MODERATE DROUGHT AFFECTING PHILLIPS AND ROOKS COUNTIES IN
WESTERN PORTIONS OF NORTH CENTRAL KANSAS.

FORTUNATELY...THE FIRST 3 WEEKS OF JANUARY PROVIDED SOME
MUCH-NEEDED MOISTURE MAINLY IN THE FORM OF SNOW...ESPECIALLY ACROSS
SOUTH CENTRAL NEBRASKA...WITH LESSER AMOUNTS IN NORTH CENTRAL
KANSAS. MOST OF THIS SNOW OCCURRED DURING TWO MAIN EVENTS...ONE
FOCUSED ON THE 9TH-10TH...AND ANOTHER ON THE 19TH. THE PROLONGED
SNOW EVENT ON THE 9TH-10TH WAS THE SNOW HIGHLIGHT OF THE WINTER SO
FAR...BLANKETING MOST OF SOUTH CENTRAL NEBRASKA WITH 7-12
INCHES...AND NORTH CENTRAL KANSAS WITH 5-9 INCHES.

THROUGH JANUARY 25TH...MOST OF SOUTH CENTRAL NEBRASKA HAS RECEIVED
BETWEEN 0.75 AND 1.5 INCHES OF PRECIPITATION LIQUID EQUIVALENT FOR
THE MONTH...OR ABOUT 150 TO 200 PERCENT OF NORMAL. MOST OF THE NORTH
CENTRAL KANSAS PORTION OF THE HSA HAS RECEIVED AROUND 0.50 TO 0.75
INCH LIQUID EQUIVALENT...GENERALLY RANGING FROM AROUND 150 PERCENT
OF NORMAL NEAR THE NEBRASKA BORDER...TO NEAR NORMAL OR EVEN SLIGHTLY
BELOW NORMAL SOUTH OF HIGHWAY 24. AT GRAND ISLAND SINCE JANUARY
1ST...1.44 INCHES OF LIQUID PRECIPITATION HAS FALLEN...MAINLY FROM
18.1 INCHES OF SNOW...RANKING THE FIRST 25 DAYS OF JANUARY AS THE
3RD-WETTEST ON RECORD. DESPITE THIS RECENT RALLY IN
PRECIPITATION...ABNORMALLY DRY CONDITIONS CONTINUE TO DOMINATE MOST
OF THE HASTINGS HSA HEADING INTO THE END OF THE MONTH.

AVERAGE 4-INCH SOIL TEMPERATURES ACROSS THE HASTINGS HSA DURING THE
PAST WEEK WERE TYPICALLY RUNNING IN THE 31-32 DEGREE RANGE...WHICH
RANGES FROM NEAR NORMAL TO 2 DEGREES ABOVE NORMAL.

...CLIMATOLOGICAL OUTLOOK...

WHILE THE NEXT FEW DAYS WILL FEATURE WELL-ABOVE AVERAGE TEMPERATURES
ACROSS THE ENTIRE HASTINGS HSA...THE LATEST 6-10 AND 8-14 DAY
OUTLOOKS FROM THE CLIMATE PREDICTION CENTER...VALID FROM THE END OF
JANUARY THROUGH THE FIRST WEEK OF FEBRUARY...INDICATE A DRASTIC
CHANGE WITH BELOW AVERAGE TEMPERATURES DOMINATING THE REGION AS A
STRONG PUSH OF ARCTIC AIR MAKES ITS WAY SOUTHWARD INTO THE PLAINS
AND SLOWLY MODERATES. THE LATEST LOCAL FORECASTS FOR EARLY NEXT WEEK
CALL FOR HIGH TEMPERATURES ONLY BETWEEN 10-20 DEGREE FOR MOST OF THE
HSA. TYPICALLY...HIGH TEMPERATURES DURING THE NEXT FEW WEEKS AVERAGE
IN THE LOW TO MID 30S ACROSS MOST OF SOUTH CENTRAL NEBRASKA...AND
UPPER 30S TO LOWER 40S IN NORTH CENTRAL KANSAS.

PRECIPITATION WISE DURING THE NEXT 6-14 DAYS...BELOW AVERAGE AMOUNTS
ARE CURRENTLY ANTICIPATED...ALTHOUGH THERE ARE SOME INDICATIONS THAT
AT LEAST LIGHT SNOW ACCUMULATIONS WILL OCCUR DURING THE JANUARY
31ST-FEBRUARY 1ST TIME FRAME.

LOOKING INTO THE MONTH OF FEBRUARY AS A WHOLE...THE LATEST MONTHLY
OUTLOOK CALLS FOR NEAR NORMAL TEMPERATURES...AND NEAR NORMAL TO
SLIGHTLY BELOW NORMAL PRECIPITATION ACROSS THE HSA. BASED ON
1971-2000 DATA...AVERAGE HIGH TEMPERATURES BY THE END OF FEBRUARY
ARE IN THE LOW TO MID 40S IN SOUTH CENTRAL NEBRASKA...AND MID TO
UPPER 40S IN NORTH CENTRAL KANSAS. AVERAGE PRECIPITATION IN FEBRUARY
IS GENERALLY IN THE 0.50 TO 0.75 INCH RANGE.

THE LATEST 30-90 DAY OUTLOOK VALID FOR THE MONTHS OF
FEBRUARY...MARCH AND APRIL SHOWS NO STRONG SIGNALS FAVORING
EITHER ABOVE OR BELOW AVERAGE TEMPERATURES...AND SUGGESTS A
CONTINUATION OF BELOW AVERAGE PRECIPITATION. BY APRIL 1ST...HIGH
TEMPERATURES TYPICALLY AVERAGE IN THE MID TO UPPER 50S IN SOUTH
CENTRAL NEBRASKA...AND LOWER 60S IN NORTH CENTRAL KANSAS.
TYPICALLY...TOTAL PRECIPITATION WITHIN THE HASTINGS HSA DURING
FEBRUARY...MARCH AND APRIL TOTALS AROUND 5 TO 5.5 INCHES.

CURRENT LONG TERM FORECAST TRENDS ARE HEAVILY INFLUENCED BY AN
ONGOING MODERATE TO STRONG LA NINA EPISODE. LA NINA IS SIGNALED BY
COOLER-THAN-NORMAL SEA SURFACE TEMPERATURES IN THE CENTRAL AND
EASTERN EQUATORIAL PACIFIC OCEAN. DURING LA NINA EPISODES...THE
WEATHER ACROSS THE HASTINGS HSA IS USUALLY HIGHLY VARIABLE...BUT
TENDS TO FAVOR SLIGHTLY WARMER THAN AVERAGE TEMPERATURES...AND BELOW
AVERAGE PRECIPITATION. THE LATEST ENSO COMPUTER MODEL FORECASTS
INDICATE THAT THE CURRENT LA NINA IS NEAR PEAK INTENSITY...BUT IS
EXPECTED TO PERSIST INTO THE SPRING MONTHS WITH AT LEAST MODERATE
INTENSITY. THERE REMAINS CONSIDERABLE UNCERTAINTY AS TO WHETHER LA
NINA CONDITIONS WILL PERSIST INTO THE SUMMER OR BEYOND...BUT THE
MAJORITY OF ENSO MODEL PREDICTIONS INDICATE A RETURN TO ENSO-NEUTRAL
CONDITIONS DURING THE LATTER HALF OF 2011.

GIVEN THE COMBINED EFFECTS OF WELL-BELOW AVERAGE PRECIPITATION OVER
THE BALANCE OF THE LAST SEVERAL MONTHS...AND THE PERSISTENCE OF AT
LEAST MODERATE LA NINA CONDITIONS INTO THE SPRING...THE LATEST U.S.
SEASONAL DROUGHT OUTLOOK VALID THROUGH APRIL CALLS FOR THE CONTINUED
DEVELOPMENT OF DROUGHT CONDITIONS ACROSS MOST OF SOUTH CENTRAL
NEBRASKA AND NORTH CENTRAL KANSAS...WITH MODERATE DROUGHT CONDITIONS
PERSISTING ACROSS PARTS OF NORTH CENTRAL KANSAS MAINLY ALONG AND
WEST OF THE HIGHWAY 183 CORRIDOR.

...ADVANCED HYDROLOGIC PREDICTION SERVICE PROBABILISTIC OUTLOOK...

THIS LONG-RANGE PROBABILISTIC OUTLOOK CONTAINS 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...AND 30 TO 90 DAY LONG-RANGE OUTLOOKS OF TEMPERATURE
AND PRECIPITATION. BY PROVIDING THE COMPLETE 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. HOWEVER...IT SHOULD BE NOTED THAT THESE PROBABILITIES DO NOT
TAKE INTO CONSIDERATION THE POSSIBILITY OF ICE JAMS...WHICH MAY
ENHANCE FLOOD POTENTIAL IN ICE JAM PRONE AREAS.

THE VALUES IN THE TABLE BELOW ARE VALID FROM JAN 30 2011 TO APR 30
2011.

IN THE TABLE BELOW...THE 90 THROUGH 10 PERCENT COLUMNS INDICATE THE
CHANCE THAT A LOCATION ON A RIVER COULD RISE ABOVE THE LISTED STAGE
LEVELS IN THE NEXT 90 DAYS. FOR EXAMPLE: THE LITTLE BLUE RIVER NEAR
DEWEESE HAS A FLOOD STAGE OF 10 FEET. THERE IS A 20 PERCENT CHANCE
THAT THE RIVER WILL RISE ABOVE 8.0 FEET IN THE NEXT 90 DAYS.


                         ALL STAGES IN FEET


LOCATION         FS(FT)   90%  80%  70%  60%  50%  40%  30%  20%  10%
--------                       ------    ---      ---       ---      ---      ---      ---      ---       ---       ---
BEAVER CREEK
BEAVER CITY        11.0    3.0    3.0     3.0     3.0     3.1    3.2     4.3    6.1     10.6

BOW CREEK
STOCKTON              9.0    3.7    3.7     3.7     3.7     3.7    3.9     4.5    5.4       6.2

CEDAR RIVER
FULLERTON            9.0    4.3    4.7     5.2     5.5     5.9    6.3     6.6    7.4       8.2

LITTLE BLUE RIVER
DEWEESE              10.0    3.6    4.4     4.9     5.5     6.0    6.5     7.3    8.0       9.1

LOUP RIVER
GENOA                      9.0     6.2   6.5     6.8      7.2     7.5    7.9     8.3    8.8       9.8

MIDDLE LOUP RIVER
SAINT PAUL             8.0     3.0   3.0     3.2      3.4      3.5    3.7     4.0   4.2        4.6

MUD CREEK
SWEETWATER       15.0   9.0    9.3   10.0    10.3   10.6  11.5   11.9  12.8    15.6

NORTH FORK SOLOMON RIVER
GLADE                      11.0   3.4   3.4     3.4      3.4      3.4     4.1     4.9    6.1      7.3

NORTH LOUP RIVER
SAINT PAUL              5.5    3.6   3.7     3.7      4.0       4.0     4.2    4.3    4.6      5.5


SAPPA CREEK
BEAVER CITY         16.0    3.2   3.2      3.2     3.2       3.2     3.3     3.8   8.5     12.7
STAMFORD             19.0    7.5   7.5      7.5     7.5       7.7     8.0     9.8  10.9    13.7

SOUTH LOUP RIVER
RAVENNA                5.0      3.2   3.3      3.6     3.8       3.9     4.1     4.3    4.4     4.9
SAINT MICHAEL     6.5      3.8   3.9      4.2     4.5       4.7     4.8     5.3    5.7     6.6

WOOD RIVER
ALDA                     10.0      4.5   4.5       4.5     4.8      5.6      6.5     6.8    8.3     9.3
GIBBON               15.0      4.2    4.2      4.2     4.4      5.4      6.3      7.0    9.6   11.2
RIVERDALE        11.0      2.1    2.1      2.1     2.4       3.1      3.7     4.2    6.1     8.6


...FUTURE OUTLOOKS...

THE NEXT OUTLOOK WILL BE ISSUED ON THURSDAY FEBRUARY 17TH.

&&

ADDITIONAL CLIMATE INFORMATION FOR THE REGION CAN BE OBTAINED AT:
WWW.HPRCC.UNL.EDU

ADDITIONAL INFORMATION ON CLIMATOLOGICAL OUTLOOKS CAN BE FOUND AT:
WWW.CPC.NCEP.NOAA.GOV

FURTHER INFORMATION ON DROUGHT CONDITIONS CAN BE OBTAINED AT:
WWW.DROUGHT.GOV
WWW.DROUGHT.UNL.EDU

INFORMATION ON MOUNTAIN SNOWPACK CAN BE FOUND AT:
WWW.WCC.NRCS.USDA.GOV/FTPREF/DOWNLOADS/WSF/201101WSFWWW.PDF

VISIT OUR WEB SITE AT: WWW.WEATHER.GOV/HASTINGS
FOR MORE WEATHER AND FLOOD INFORMATION.

$$

WESELY/PFANNKUCH



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