Flood Potential Outlook
Issued by NWS Raleigh/Durham, NC

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WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE RALEIGH NC
300 PM EST THU MAR 5 2015

...WINTER/SPRING FLOOD POTENTIAL OUTLOOK FOR CENTRAL NORTH
CAROLINA...

...THE RISK OF RIVER FLOODING ACROSS CENTRAL NORTH CAROLINA THROUGH
SPRING IS NEAR NORMAL.....

PRECIPITATION SUMMARY

PRECIPITATION ACROSS CENTRAL NORTH CAROLINA FOR THE WATER YEAR
(OCTOBER 2014 TO PRESENT) CONTINUES TO SHOW A MARKED GRADIENT RANGING
FROM BELOW NORMAL (AS LITTLE AS 70% OF NORMAL) ACROSS THE WEST IN THE
YADKIN/PEE DEE RIVER BASIN TO AS MUCH AS 120% ABOVE NORMAL ACROSS
THE EAST (GENERALLY THE MID TO LOWER REACHES OF THE CAPE FEAR...
NEUSE...AND TAR RIVER BASINS).

THE RAINFALL DEFICIT IN THE YADKIN RIVER BASIN NOTED ABOVE IS THE
PRIMARY DRIVER FOR MAINTAINING ABNORMALLY DRY DROUGHT CONDITIONS IN
THE NORTHWEST PIEDMONT...WHERE THE DEFICIT SINCE OCTOBER HOVERS FROM
70 TO 80 PERCENT OF NORMAL IN FORSYTH...GUILFORD...AND DAVIDSON
COUNTIES.

THE FOLLOWING TABLES SUMMARIZE PRECIPITATION AND MONTHLY DEFICITS.

               PRECIPITATION (INCHES)/DEPARTURE FROM NORMAL
               WATER YEAR (BEGINNING 1 OCTOBER 2014)TO DATE

    MONTH           RDU           GSO        FAYETTEVILLE
---------------------------------------------------------------------

  OCTOBER       2.18/-1.07     2.01/-1.12     1.31/-1.90
  NOVEMBER      3.78/ 0.66     3.33/ 0.22     2.84/ 0.07
  DECEMBER      4.97/ 1.90     2.21/-0.77     4.22/ 1.57
  JANUARY       3.35/-0.15     2.04/-1.02     4.37/ 1.07
  FEBRUARY      2.91/-0.32     2.64/-0.32     3.28/ 0.52
  MARCH TO DATE 0.76/ 0.11     0.62/ 0.04     0.22/-0.29

  TOTALS       17.95/ 1.13    12.85/-2.97    16.24/ 1.02

  % OF NORMAL      107             81            107


                            ACTUAL   NORMAL  DEPARTURE  PERCENT
                             PCPN     PCPN   FROM NORM  OF NORM

RALEIGH-DURHAM INTERNATIONAL AIRPORT (RDU)

 LAST   7 DAYS   02/26/2015   1.48    0.88      0.60      168%
 LAST  14 DAYS   02/19/2015   2.04    1.74      0.30      117%
 LAST  30 DAYS   02/03/2015   3.28    3.52     -0.24       93%
 LAST  90 DAYS   12/05/2014  11.99    9.91      2.08      121%
 LAST 180 DAYS   09/06/2014  22.68   20.26      2.42      112%
 LAST 365 DAYS   03/05/2014  56.95   43.34     13.61      131%

PIEDMONT TRIAD INTERNATIONAL AIRPORT (GSO)

 LAST   7 DAYS   02/26/2015   0.67    0.80     -0.13       84%
 LAST  14 DAYS   02/19/2015   1.48    1.60     -0.12       92%
 LAST  30 DAYS   02/03/2015   2.55    3.22     -0.67       79%
 LAST  90 DAYS   12/05/2014   7.18    9.05     -1.87       79%
 LAST 180 DAYS   09/06/2014  13.89   19.14     -5.25       73%
 LAST 365 DAYS   03/05/2014  34.69   42.20     -7.51       82%

FAYETTEVILLE AIRPORT (FAY)

 LAST   7 DAYS   02/26/2015   0.81    0.71      0.10      114%
 LAST  14 DAYS   02/19/2015   2.04    1.43      0.61      143%
 LAST  30 DAYS   02/03/2015   2.99    3.01     -0.02       99%
 LAST  90 DAYS   12/05/2014  12.01    8.67      3.34      139%
 LAST 180 DAYS   09/06/2014  22.37   18.76      3.61      119%
 LAST 365 DAYS   03/05/2014  42.86   44.46     -1.60       96%

STREAMFLOW AND LAKE LEVELS

IN THE SHORT TERM...THERE HAVE BEEN THREE SIGNIFICANT (>0.25
INCHES) REASONABLY WIDESPREAD PRECIPITATION EVENTS ACROSS CENTRAL NORTH
CAROLINA FROM LATE FEBRUARY INTO EARLY MARCH. THIS INCLUDED AN
ANOMALOUS LATE SEASON SNOWSTORM WHICH PRODUCED SNOWFALL RANGING FROM
3 TO AS MUCH AS 9 INCHES ACROSS A COUPLE OF NORTHERN TIERS OF
COUNTIES NEAR THE VIRGINIA BORDER. THE NET RESULTS WERE SIGNFICANT
RISES ON EASTERN RIVERS...WHICH REMAINED BELOW MINOR FLOOD STAGE DUE
IN LARGE PART TO THE DELAYED RUNOFF OF SNOWMELT. AVERAGE STREAMFLOW
FOR THE PAST 4 WEEKS REFLECTS THE SAME PATTERN...WITH FLOWS IN THE
NORMAL RANGE OVER THE EASTERN HALF OF THE AREA...AND BELOW NORMAL IN
THE WEST.

THE LARGER WATER SUPPLY RESERVOIRS LOCATED IN CENTRAL NC...FALLS
LAKE AND LAKE JORDAN...BOTH OPERATED BY THE U.S. ARMY CORPS OF
ENGINEERS...HAD ONLY 50 TO 60 PERCENT OF NORMAL INFLOW FOR FEBRUARY.
BOTH LAKES BENEFITTED FROM THE SNOWSTORM IN LATE FEBRUARY...
HOWEVER...AND REBOUNDED SO THAT BOTH ARE CURRENTLY AROUND A FOOT
ABOVE THEIR TARGET POOL ELEVATIONS.

SHORT TERM FORECAST

AN ACTIVE SOUTHERN BRANCH OF THE JET STREAM IS EXPECTED TO PRODUCE A
WET PERIOD ACROSS THE STATE...AND ESPECIALLY ACROSS THE SOUTH AND
EAST...DURING THE WEEK OF MARCH 8TH. HOWEVER...THERE IS NO CLEAR
SIGNAL FOR A RAINFALL EVENT THAT MIGHT INCREASE CONFIDENCE IN HAVING
A WIDESPREAD HEAVY EVENT. IN THE SHORT TERM...IT IS ESTIMATED THAT
WE WOULD REQUIRE A WIDESPREAD EVENT OF ~1.5 INCHES OF RAIN TO CAUSE
RIVER FLOODING OF ANY CONSEQUENCE. AS SUCH...THE SHORT RANGE CHANCE
FOR RIVER FLOODING IS CLASSIFIED AS NEAR NORMAL HEADING INTO MID
MARCH.

LONG TERM PRECIPITATION OUTLOOK

CLIMATOLOGICALLY...THE FREQUENCY OF RIVER FLOODING PEAKS IN MARCH
AND APRIL OVER CENTRAL NORTH CAROLINA. AN EL NINO ADVISORY HAS BEEN
POSTED WITH AN INCREASED (50% - 60%) CHANCE OF WEAK EL NINO
CONDITIONS DEVELOPING DURING THE SPRING. WHILE THIS WOULD MARGINALLY
INCREASE THE PROBABILITY OF ENHANCED RAIN OVER THE SOUTHEASTERN
UNITED STATES...THE LATE DEVELOPMENT AND 50% PROBABILITY OF ITS
DEVELOPING DO NOT INCREASE CONFIDENCE IN RIVER FLOODING TO A
SIGNIFICANT DEGREE. AS SUCH...THE LONGER RANGE CHANCE FOR RIVER
FLOODING REMAINS CATEGORIZED AS NEAR NORMAL.

ADDITIONAL DETAILS MAY BE FOUND AT THE CLIMATE PREDICTION CENTER
WEBSITE:

HTTP://WWW.CPC.NCEP.NOAA.GOV

IN SUMMARY...CURRENT CONDITIONS ARE RATHER WET ACROSS EASTERN NORTH
CAROLINA. CONDITIONS IN THE WEST HAVE IMPROVED MARGINALLY...BUT ARE
STILL ABNORMALLY DRY. THERE ARE NO SYSTEMS IN THE SHORT RANGE
FORECAST LIKELY TO PRODUCE ENOUGH PRECIPITATION (>1.5 INCHES) TO
CAUSE RIVER FLOODING OF ANY CONSEQUENCE. AS SUCH...THE CHANCE FOR
RIVER FLOODING THROUGH MID MARCH IS CATEGORIZED AS NEAR NORMAL.

THERE HAS BEEN A SHIFT TOWARDS A MARGINALLY WETTER OUTLOOK FOR THE
SPRING DUE TO POTENTIAL DEVELOPMENT OF A WEAK EL NINO. HOWEVER...
THERE IS NOT ENOUGH CONFIDENCE IN THIS PATTERN CHANGE YET TO
CONSIDER THE CHANCE OF RIVER FLOODING TO BE ABOVE NORMAL. THUS THE
CHANCE FOR RIVER FLOODING FOR THE SPRING IS ALSO CATEGORIZED AS NEAR
NORMAL.

THE NEXT WINTER/SPRING FLOOD POTENTIAL OUTLOOK WILL BE ISSUED ON
MARCH 19TH.

MLM



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