Spring Flood Outlook 2018

Winter/Spring Flood Potential Outlook
National Weather Service Columbia SC
439 PM EDT Wed Apr 11 2018


...Spring Flood Potential Outlook...

...Expect below normal to near normal potential of river flooding
across the Midlands and Central Savannah River Area...

This Spring Flood Potential Outlook is for rivers and tributaries
of the Central Savannah River Basin...East-Central Georgia and
Central South Carolina including the following:

Savannah River Basin Downstream of R. B. Russell Reservoir and
upstream from Burtons Ferry...

The Edisto River basin upstream of the Bamberg and Orangeburg
County line in South Carolina...

The Santee River Basin upstream of the Clarendon and Berkeley
County line and downstream on the Saluda and Broad Rivers at the
Greenwood/Saluda...Laurens/Newberry...Union/Fairfield and the
Chester/Fairfield County lines in South Carolina...

The Wateree River System downstream of Great Falls South
Carolina...

The Great Pee Dee River Basin in Chesterfield County in South
Carolina...

           ...Summary of Recent Weather Events...

Over the last 14 days ending April 11 2018...the hydrologic area
received rainfall amounts that ranged from one half inch up to 2
inches. The heaviest rain fell across the eastern Midlands and
along and south of the I-20 corridor. This ranges from 50 to 90
percent across the western and central Midlands and Central
Savannah River Area up to 100 to 150 percent of normal across the
eastern Midlands.

           ...Soul Moisture-Drought Conditions...

Here is a breakdown of the current conditions across the Midlands
and CSRA.

Rainfall over the past 2 weeks has been at or below normal across
the Midlands and CSRA. This has resulted in a slight increase of
D0, abnormally dry, coverage. This extends across nearly all of
the central and eastern Midlands. The area of D1, moderate
drought, has increased across the Central Savannah River Area and
along the coast of South Carolina. The area of D2, severe drought,
has crept westward from the Lowcountry and coastal areas into the
far eastern and southern Midlands. This includes portions of the
counties of Orangeburg, Bamberg and Barnwell. Rainfall amounts
around one inch are expected over the next 7 days.

Go to www.drought.gov for more details.


           ...River and Stream Flow...

Looking at the 14 day stream flow average compared to historical
streamflows for April 11 2018 show most of the stream basins
across the Midlands and CSRA have much below to below normal flow
conditions. The stream basins that are near normal flows include
the Santee River Basin. The stream basins that have flows that
are much below to below normal flows include the Savannah River
Basin, the Edisto River Basin, the Lynches River basin, the Pee
Dee River Basin, Saluda River Basin and the Catawba River Basin.
Note, many stream flows across the area are impacted by reservoir
project operations.

Broad River Basin: Below Normal flows
Catawba/Wateree River Basin: Much Below Normal/Below Normal flows
Saluda River Basin: Below Normal flows
Santee River Basin: Near Normal flows
Edisto River Basin: Much Below Normal flows
Savannah River Basin: Much Below Normal flows

           ...Reservoir Levels...

Reservoir pool elevations rose over the past 2 weeks across the
Midlands and CSRA. Areas along the Savannah River Basin are
below normal for their early Spring target pool/guide curves.
The Saluda...Santee and Wateree Basins remain near or just above
their Winter target pool/guide curves. Note, reservoir pool
elevations are dependent on project operations.

Lake Thurmond (FP 330.0 Feet)...
Mar 29 2018    327.27 Feet
Apr 11 2018    327.39 Feet
Difference Plus  0.12 Feet

Lake Greenwood (FP 440.0 Feet)...
Mar 29 2018    438.14 Feet
Apr 11 2018    438.93 Feet
Difference Plus  0.79 Feet

Lake Murray (FP 360.0 Feet)...
Mar 29 2018    357.98 Feet
Apr 11 2018    358.11 Feet
Difference Plus  0.13 Feet

Lake Marion (FP 76.8 Feet)...
Mar 29 2018     75.30 Feet
Apr 11 2018     75.21 Feet
Difference Minus 0.09 Feet

Lake Wateree (FP 100.00 Feet)...
Mar 29 2018     97.49 Feet
Apr 11 2018     97.43 Feet
Difference Minus 0.06 Feet

Data for this segment was gathered from the United States
Geological Survey...the United States Army Corps of
Engineers...Duke Energy...South Carolina Electric and
Gas...Greenwood County and Santee Cooper.


      ...Precipitation and Temperature Outlooks...

Near Term...A cold front will move across the area on Sunday. This
will bring a chance of showers and thunderstorms to the region.
Rainfall totals are expected to be around 1 inch.

Please see the Gridded Forecasts for the chance of rain over the
next 7 days at weather.gov/cae.

The 8 to 14 day outlook for the period April 18 to 24 calls for a
33 to 40 percent chance of above normal temperatures with a 33 to
40 percent chance of above normal precipitation.

The 30-day outlook for April 2018 indicates equal chances for
above, below and normal temperatures along with a 33 to 40 percent
chance of above normal precipitation.

The 3-month outlook for April, May and June calls for a 50 to 60
percent chance of above normal temperatures along with equal
chances for above, below and normal precipitation.

Go to the Climate Prediction Center webpage at
www.cpc.ncep.noaa.gov for more details and the latest outlooks.

                   ...Summary/Outlook...

Due to the recent rainfall deficits over the past couple of
months, the Spring Flood Outlook calls for a reduced risk of river
flooding across Central South Carolina and East-Central Georgia.

Historically...the River Flood Season begins in early to mid
January with the number of river flood events increasing through
late Winter into early Spring. The peak occurs in early to mid
March then begins to end in late April for the region.

The medium to long range precipitation guidance indicates little
confidence in the region receiving above normal precipitation
through the Spring season. Stream flows, on average, have
continued to be much below normal to below normal across much of
the region through the Winter and into Spring. However, over the
past couple of weeks most reservoir pool heights have risen. The
area Reservoirs along the Savannah River are running below target
pool or guide curves. The Santee and Catawba River Reservoirs are
running near or just above normal for their target pool/guide
curves for late March. This combined with the gradual increase in
pool heights for Summer recreation indicates the the risk of river
flooding downstream from these projects is below normal.

The next schedule Winter/Spring Flood Outlook is scheduled for
Thursday April 26 2018.


                ...Questions and Comments...

If you have any questions or comments about this outlook please
contact...

The National Weather Service
2909 Aviation Way
West Columbia SC 29170
Phone: 803-822-8135
Internet Address: caewx@noaa.gov
Senior Service Hydrologist:
Leonard.Vaughan@noaa.gov


$$

Vaughan