Flood Potential Outlook
Issued by NWS Raleigh/Durham, NC

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Winter/Spring Flood Potential Outlook
National Weather Service Raleigh, NC
115 PM EST Mon Jan 23 2017

...THE CHANCE OF RIVER FLOODING FROM LATE JANUARY THROUGH SPRING IS
NEAR NORMAL...

Precipitation Summary

Rainfall has been sparse over eastern NC during the past 2 weeks,
but the western Piedmont (the Yadkin and Haw river basins) were
the beneficiaries of a two-plus inch rainfall event over the
weekend of the 21st. This was a particularly favorable distribution,
as the maximum rainfall fell over the only area in the Raleigh
hydrologic service area which was still suffering from moderate
drought.

See www.water.weather.gov for detailed rainfall analysis.

Precipitation and departure from normal:

          Precipitation (inches) and departure from normal
            for the water year beginning 1 October 2016

    Month                RDU            GSO        Fayetteville
------------------------------------------------------------------

  October             7.10/ 3.85     3.91/ 0.78    15.07/11.81
  November            0.60/-2.52     1.02/-2.09     0.81/-1.96
  December            2.19/-0.88     1.70/-1.28     2.64/-0.01
  January(to date)    3.41/ 0.92     4.21/ 2.01     2.34/ 0.21

Total precip   (YTD) 13.30/ 1.37    10.84/-0.58    20.86/10.05
Percent normal (YTD)     111             95            193

                  Begin     Actual   Normal  Departure  Percent
                  date       Pcpn     Pcpn   from norm  of norm

Raleigh-Durham International Airport (RDU)

 LAST   7 DAYS   06/04/2014   0.31    0.83     -0.52       37%
 LAST  14 DAYS   05/28/2014   0.44    1.70     -1.26       26%
 LAST  30 DAYS   05/12/2014   4.31    3.43      0.88      126%
 LAST  90 DAYS   03/13/2014  11.69    9.90      1.79      118%
 LAST 180 DAYS   12/13/2013  24.71   20.11      4.60      123%
 LAST 365 DAYS   06/11/2013  44.49   43.34      1.15      103%

PIEDMONT TRIAD INTERNATIONAL AIRPORT (GSO)

 LAST   7 DAYS   06/04/2014   1.01    0.88      0.13      115%
 LAST  14 DAYS   05/28/2014   1.53    1.77     -0.24       86%
 LAST  30 DAYS   05/12/2014   3.30    3.52     -0.22       94%
 LAST  90 DAYS   03/13/2014   9.44   10.53     -1.09       90%
 LAST 180 DAYS   12/13/2013  22.22   19.76      2.46      112%
 LAST 365 DAYS   06/11/2013  45.90   42.20      3.70      109%

FAYETTEVILLE AIRPORT (FAY)

 LAST   7 DAYS   06/04/2014   0.08    1.02     -0.94        8%
 LAST  14 DAYS   05/28/2014   0.53    2.09     -1.56       25%
 LAST  30 DAYS   05/12/2014   4.16    3.91      0.25      106%
 LAST  90 DAYS   03/13/2014  10.00    9.84      0.16      102%
 LAST 180 DAYS   12/13/2013  21.73   18.59      3.14      117%
 LAST 365 DAYS   06/11/2013  42.93   44.46     -1.53       97%

Streamflow and lake levels

Streamflow on streams and rivers across west-central NC are well
above normal, flowing in 90th percentile for the time of year.
All others are on the high side of normal.

See https://waterwatch.usgs.gov for additional details.

The major water supply and flood control reservoirs in central NC
are Falls Lake and B. Everett Jordan Lake, both operated by the U.S.
Army Corps of Engineers. Falls Lake elevation is at 252.0 feet,
which is half a foot above its target elevation. B. Everett Jordan
Lake elevation is 216.8 feet, a foot above target elevation. As
such, water allocations for water supply and power generation are
100 percent at both lakes, with ~98% of flood storage available
should that capacity be needed.

See www.epec.saw.usace.army.mil for additional details.

Short term forecast

A transition to northwest flow leading to a cooler and drier
pattern is underway early this week. As such, both temperatures
and rainfall into early February are expected to be below normal.
The chance of river flooding in the short term is below normal.

Longer term precipitation outlook

We are currently in a weakening La Nina phase of the El
Nino/Southern Oscillation (ENSO) cycle. A pronounced La Nina
typically produces an increased chance for warmer and drier than
normal conditions during the winter/spring over central NC. As the
La Nina phase is expected to continue weakening and become neutral
over the next 1-2 months, the tendency towards drier conditions will
be diminishing as well. With the antecedent near normal moisture
conditions and weakening climatological signal favoring drier
conditions, the longer range chance of river flooding is near
normal.

Additional details and discussion may be found at the Climate
Prediction Center website: http://www.cpc.ncep.noaa.gov

In summary, current hydrologic conditions are near normal across
central NC. There no hints of any system in the near-term which
would be capable of producing significant rain, thus there is
a below normal chance for flooding through early February.
Similarly, there are no strong climatological signals which might
point towards prolonged wet periods in the longer range outlook.
However, given the lower confidence in this outlook, the chance
of river flooding for mid-February through Spring is near normal.

The next scheduled Winter/Spring flood outlook will be issued
on February 2nd.

For additional hydrologic or weather information, visit our website
at www.weather.gov/raleigh.

MLM



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