Flood Potential Outlook
Issued by NWS Greer, SC

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302117-

SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
517 PM EDT THU MAR 16 2017

...The sixth and final Spring Flood Potential Outlook increases
flood potential SLIGHTLY for mainstem rivers across the central and
southern North Carolina mountains from WELL-BELOW NORMAL to BELOW
NORMAL while flood potential for the rest of the Western Carolinas
and northeast Georgia remains BELOW NORMAL to WELL-BELOW NORMAL
through April 2017...

=====================
ABOUT THIS PRODUCT...
=====================

Every two weeks from January through mid-March, NWS Greenville-
Spartanburg (GSP) issues a Flood Potential Outlook for the entire
service area (see county-to-region legend at the end of this outlook
for a list of counties serviced by NWS GSP).  These outlooks
forecast the potential for runoff, small stream, and mainstem river
flooding through late April, or the end of the winter recharge
season. The outlook is prepared based on an assessment of several
hydrometeorological factors, including recent and forecasted
precipitation and observed soil moisture, groundwater levels,
streamflows, reservoir levels, and recent flooding events.

This product is also located at:

http://weather.gov/gsp/floodoutlook

For additional hydrological and meteorological information please
visit:

http://weather.gov/gsp/drought

===============
HISTORICALLY...
===============

The mainstem river flood season typically begins in late December.
The quantity...frequency...magnitude...and significance of river
flood events often increases through late winter with a peak in
early to mid-March. While the mainstem river flood season typically
ends by late April for the region, small stream flash flooding can
occur year-round.  The mainstem flood season began with severe to
extreme drought across much of the region and, as a result, it will
take more frequent and more significant precipitation through April
to increase the chance of mainstem flood occurrence across the
region.

=============================================
14-DAY OBSERVED PRECIPITATION and FLOODING...
=============================================

For the LATEST PRECIPITATION ESTIMATES for the region, please visit:
http://water.weather.gov/precip or http://climate.ncsu.edu/precip

---------------------------------------------------------------------

REGION        OBSERVED    % OF      MAINSTEM    SMALL STREAM
              PRECIP      NORMAL    FLOODING    FLOODING
              (in)

NC Piedmont   0.40-2.00 |  40- 90 | None      | None
NC Foothills  1.00-2.00 |  50- 95 | None      | None
NC Nrn Mnts   1.50-1.90 |  50- 95 | NA        | None
NC Cntl Mnts  1.00-4.50 |  70-120 | None      | None
NC Srn Mnts   1.40-3.70 |  40-110 | None      | None

SC Mnts       1.70-2.50 |  40- 60 | NA        | None
SC Foothills  1.50-2.50 |  40- 80 | None      | None
SC Piedmont   1.20-2.60 |  50-110 | None      | None

GA NE Mnts/   1.50-3.50 |  40- 90 | None      | None
   Foothills
GA Piedmont   1.10-2.20 |  30- 80 | None      | None

---------------------------------------------------------------------

==========================
SNOW DEPTH and FORECAST...
==========================

All current snowpack in the region will melt by March 20th given a
return to normal to above-normal temperatures.

---------------------------------------------------------------------

REGION        SNOW   SNOW WATER  7-DAY SNOWFALL
              DEPTH  EQUIVALENT  FORECAST
              (in)   (in)        (in)

NC Piedmont   None | None      | None
NC Foothills  None | None      | None
NC Nrn Mnts   0-4  | 0-0.50    | T-1 (Highest Elevs. Only)
NC Cntl Mnts  0-4  | 0-1       | None
NC Srn Mnts   0-2  | 0-0.25    | None

SC Mnts       0-T  | 0-0.05    | None
SC Foothills  None | None      | None
SC Piedmont   None | None      | None

GA NE Mnts/   0-T  | 0-0.05    | None
   Foothills
GA Piedmont   None | None      | None

---------------------------------------------------------------------

=============================================================
1-10 DAY FUTURE PRECIPITATION FORECAST and FLOOD POTENTIAL...
=============================================================

The current 10-Day precipitation forecast is promising and would
provide some notable water recharge.  If every 10-day period
featured this amount of rainfall through mid-April, the chances
for small-stream and, to a lesser extent, mainstem river flooding
would increase at least slightly for most regions.

* The precipitation outlook is based on the best available guidance
at the issuance time of this statement.

For the LATEST FORECAST for the region, please visit:
http://weather.gov/gsp
and enter your zip code or click on the Watch, Warning, and
Advisories (WWA) map.

For the LATEST DISCUSSION for the region, please visit:
http://weather.gov/gsp
and click on the Forecaster`s Discussion link below the WWA map

---------------------------------------------------------------------

REGION        10-DAY      MAINSTEM     SMALL STREAM
              PRECIP      FLOOD PTNTL  FLOOD PTNTL
              (in)

NC Piedmont   0.75-1.25 | Zero       | Zero
NC Foothills  1.00-2.00 | Zero       | Zero
NC Nrn Mnts   1.50-1.75 | NA         | Zero
NC Cntl Mnts  1.50-2.50 | Zero       | Very Slight
NC Srn Mnts   2.00-3.25 | Zero       | Very Slight

SC Mnts       2.00-3.00 | NA         | Zero
SC Foothills  1.00-2.50 | Zero       | Zero
SC Piedmont   1.00-1.50 | Zero       | Zero

GA NE Mnts/   2.00-3.00 | Zero       | Near Zero
   Foothills
GA Piedmont   0.75-2.00 | Zero       | Zero

---------------------------------------------------------------------

==================================
8-90 DAY PRECIPITATION OUTLOOKS...
==================================

For the latest 8-14 Day Outlook, please visit:
http://www.cpc.ncep.noaa.gov/products/predictions/814day/
interactive/index.php

For the latest 15-30 Day Outlook and Discussion, please visit:
http://www.cpc.ncep.noaa.gov/products/predictions/WK34/

For the latest 30-90 Day Outlooks, please visit:
http://www.cpc.ncep.noaa.gov/products/predictions/long_range/

---------------------------------------------------------------------

REGION        8-14 DAY          15-30 DAY         30-90 DAY
              PRECIP            PRECIP            PRECIP
              OUTLOOK           OUTLOOK           OUTLOOK

NC Piedmont   Slight Abv Nrml | Above Normal    | Equal Chances
NC Foothills  Slight Abv Nrml | Above Normal    | Equal Chances
NC Nrn Mnts   Above Normal    | Above Normal    | Equal Chances
NC Cntl Mnts  Above Normal    | Above Normal    | Equal Chances
NC Srn Mnts   Slight Abv Nrml | Above Normal    | Equal Chances

SC Mnts       Slight Abv Nrml | Above Normal    | Equal Chances
SC Foothills  Slight Abv Nrml | Above Normal    | Equal Chances
SC Piedmont   Slight Abv Nrml | Slight Abv Nrml | Equal Chances

GA NE Mnts/   Slight Abv Nrml | Slight Abv Nrml | Equal Chances
   Foothills
GA Piedmont   Slight Abv Nrml | Slight Abv Nrml | Equal Chances

Note that Equal-Chances means there are equal chances for
above-normal...normal...and below-normal precipitation during
the given period.  In other words, there is no clear signal for
precipitation during the given period.

---------------------------------------------------------------------

=====================================================================
HYDROLOGIC SUMMARY...
=====================================================================

--------------------
..IMPORTANT NOTES...
--------------------

It is very important to note that flash flooding and flooding
of smaller tributaries is still very possible during periods of
drought.  Several important and damaging flash floods have
were observed this past summer despite the drought.  Residents are
strongly encouraged to heed related flood advisories and warnings,
even during significant drought.

The winter and early spring months are a critical time for the water
system as widespread winter precipitation normally restores
streamflows and reservoir levels following the spotty, convective
nature of precipitation during the summer and the drier weeks of
early fall.  This recharge of the water system is critical for
adequate water supply heading into the late spring and summer of
2017.  When the winter begins in a significant drought, it takes a
greater amount of precipitation to adequately complete this recharge.

---------------------------
..SOIL and CROP MOISTURE...
---------------------------

More frequent precipitation events have allowed soil moisture values
to recover slightly from the extreme anomalies present last autumn,
but the precipitation has not been frequent or significant enough
to allow for full recharge.  The effects of this incomplete recharge
can be measured throughout all hydrologic systems as without adequate
soil moisture content, saturation, runoff, and subsurface
infiltration cannot sufficiently occur.

----------------
..GROUNDWATER...
----------------

Most wells across the region have seen modest decreases in water
depth below the surface as rainfall amounts have increased across the
region since the very dry months of October and November.  However,
many of these wells are still well below their monthly median levels
and remain below the 50th percentile.  Therefore, groundwater
recharge has remained anemic this winter and is forecasted to remain
weak through early April.

---------------
..STREAMFLOW...
---------------

Winter 2016-2017 was a whipsaw of monthly precipitation totals, with
December being below-normal, January being near-normal to slightly
above-normal, and February being well-below normal.  January`s
rainfall was sufficient enough to allow for modest recovery in
streamflows across the area. However, the devastatingly low
precipitation values in February returned many area rivers to near
record lows.  Therefore, a prolonged period of near-normal
rainfall would be required to erase medium-range (i.e., 28-day)
deficits.  The southern North Carolina Piedmont within the lower
Catawba and upper Rocky River basins once had near-normal to slightly
above-normal streamflows and was no longer in any drought
classification, but that has since changed as precip deficits
increased once again.

---------------
..RESERVOIRS...
---------------

Even though the majority of the region has received below-normal to
slightly below normal precipitation since late November, it has been
enough to bring most major reservoirs in the region back to target
elevations for this time of year.  In most reservoirs across the
Catawba, Nantahala, Little Tennessee, and Tuckasegee river basins,
pool elevations are actually near their target pools, while
Tennessee Valley Authority (TVA) projects are at or above their
flood guide curves (i.e., winter target pools).

However, guide curves are rapidly rising as operators prepare
to increase storage for summer demands. This means that if rainfall
does not increase, prompting an increase in stream flows into
major area reservoirs, actual pool elevations will hold steady
or fall as target pool elevations rise, increasing storage deficits
as summer approaches and demand peaks.

Finally, the significant exception to reservoir recharge has been in
the Savannah Basin, where Lake Hartwell remains over 9 feet below
winter full pool. This is a significant deficit that will only be
erased by a prolonged period of above-normal rainfall.

==========================
LONG-TERM FLOOD OUTLOOK...
==========================

Therefore, given current antecedent conditions and long-range
precipitation guidance, the long-term flood outlook through the
end of April 2017 is as follows...

---------------------------------------------------------------------

REGION        RUNOFF            SMALL             MAINSTEM
              POTENTIAL         STREAMS           RIVERS

NC Piedmont   Slight Blw Nrml | Slight Blw Nrml | Below Normal
NC Foothills  Slight Blw Nrml | Slight Blw Nrml | Well-Below Normal
NC Nrn Mnts   Near Normal     | Near Normal     | NO MAINSTEMS
NC Cntl Mnts  Slight Blw Nrml | Slight Blw Nrml | Below Normal
NC Srn Mnts   Slight Blw Nrml | Below Normal    | Below Normal

SC Mnts       Slight Blw Nrml | Below Normal    | NO MAINSTEMS
SC Foothills  Below Normal    | Below Normal    | Well-Below Normal
SC Piedmont   Slight Blw Nrml | Below Normal    | Well-Below Normal

GA NE Mnts/   Slight Blw Nrml | Below Normal    | Well-Below Normal
   Foothills
GA Piedmont   Below Normal    | Well-Below Nrml | Near Zero

---------------------------------------------------------------------

==================
ACKNOWLEDGMENTS...
==================

The precipitation analysis is derived from quality-controlled
gridded precipitation estimates produced at the Lower Mississippi
River Forecast Center (LMRFC) and the Southeast River Forecast
Center (SERFC).

The 1-10 day future precipitation is derived from guidance produced
by NWS Greenville-Spartanburg.

The long-term precipitation outlooks are derived from guidance
produced at the Climate Prediction Center (CPC).

Streamflow information is courtesy of the United States Geological
Survey (USGS).

Reservoir information is courtesy of Duke Energy...Georgia Power...
and the US Army Corps of Engineers (USACE).

The general outlook is produced in collaboration with the LMRFC and
the SERFC.

=====================
NEXT ISSUANCE DATE...
=====================

No additional Flood Outlook Products will be issued this spring.
The next Winter/Spring Flood Outlook Product will be issued in early
January, 2018.

=======================
ADDITIONAL RESOURCES...
=======================

For the latest LEVELS of streams and mainstem rivers across the
region please visit and bookmark:

http://water.weather.gov/ahps2/
area.php?wfo=gsp&hydro_type=0&hsa_type=1

For the latest status of DROUGHT conditions across the region please
visit and bookmark:

http://weather.gov/gsp/drought

==========================
COUNTY TO REGION LEGEND...
==========================

------------
..GEORGIA...
------------

COUNTY         REGION

Elbert         GA Piedmont
Franklin       GA Piedmont
Habersham      GA NE Mountains/Foothills
Hart           GA Piedmont
Rabun          GA NE Mountains/Foothills
Stephens       GA NE Mountains/Foothills

-------------------
..NORTH CAROLINA...
-------------------

COUNTY         REGION (SUBREGION)

Alexander      NC Foothills (Northern)
Avery          NC Northern Mountains
Buncombe       NC Central Mountains
Burke          NC Foothills (Northern)
Cabarrus       NC Piedmont (Southern)
Caldwell       NC Foothills (Northern)
Catawba        NC Foothills (Northern)
Cleveland      NC Piedmont (Southern)
Davie          NC Piedmont (Northwest)
Gaston         NC Piedmont (Southern)
Graham         NC Central Mountains
Haywood        NC Central Mountains
Henderson      NC Southern Mountains
Iredell        NC Piedmont (Northwest)
Jackson North  NC Central Mountains
Jackson South  NC Southern Mountains
Lincoln        NC Piedmont (Southern)
Macon          NC Southern Mountains
Madison        NC Central Mountains
McDowell       NC Foothills (Northern)
Mecklenburg    NC Piedmont (Southern)
Mitchell       NC Northern Mountains
Polk           NC Foothills (Southern)
Rowan          NC Piedmont (Northwest)
Rutherford     NC Foothills (Southern)
Swain          NC Central Mountains
Transylvania   NC Southern Mountains
Union          NC Piedmont (Southern)
Yancey         NC Northern Mountains

-------------------
..SOUTH CAROLINA...
-------------------

COUNTY         REGION (SUBREGION)

Abbeville      SC Piedmont (Lower)
Anderson       SC Piedmont (Northern)
Cherokee       SC Piedmont (Northern)
Chester        SC Piedmont (Eastern)
Greenville     SC Mountains/Foothills
Greenwood      SC Piedmont (Lower)
Laurens        SC Piedmont (Lower)
Oconee         SC Mountains/Foothills
Pickens        SC Mountains/Foothills
Spartanburg    SC Mountains/Foothills
Union          SC Piedmont (Eastern)
York           SC Piedmont (Eastern)

========================
MAINSTEM RIVER LEGEND...
========================

REGION        RIVER

NC Piedmont   Catawba           (Heavily Regulated)
              South Fork Catawba
              Rocky
              Yadkin            (Regulated)
NC Foothills  Broad             (Regulated)
              Catawba           (Regulated)
NC Nrn Mnts   NONE
NC Cntl Mnts  French Broad
              Little Tennessee
              Nantahala
              Oconaluftee
              Pigeon
              Tuckasegee
NC Srn Mnts   French Broad
              Little Tennessee
              Nantahala          (Regulated)
              Tuckasegee         (Regulated)
SC Mnts       NO MAINSTEM RIVERS
SC Foothills  Chatooga
              Enoree
              Pacolet
              Reedy
              Saluda             (Slightly Regulated)
              Savannah           (Heavily Regulated)
              Toxaway/Seneca     (Heavily Regulated)
              Tyger
SC Piedmont   Broad              (Regulated)
              Pacolet
              Reedy
              Saluda             (Regulated)
              Savannah           (Heavily Regulated)
              Tyger
GA NE Mnts/   Chatooga
   Foothills  Tallulah/Tugaloo   (Regulated)
GA Piedmont   Broad
              Savannah           (Heavily Regulated)

========================
QUESTIONS or COMMENTS...
========================

This product has undergone several revisions and enhancements during
the most recent flood outlook period.  Additional enhancements are
planned for future flood outlooks. Your feedback and recommendations
are encouraged in order to ensure this product meets user needs.
Please direct feedback, recommendations, questions, and comments to:

National Weather Service
Weather Forecast Office - Greenville-Spartanburg
1549 GSP Drive
Greer SC 29651
Phone 864-848-9970 x234
joshua.palmer@noaa.gov

$$

JMP




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