Mesoscale Precipitation Discussion 0854...Corrected
NWS Weather Prediction Center College Park MD
101 AM EDT Mon Sep 17 2018

Corrected for change to areas affected

Areas affected...eastern SC into south-central NC/southeastern NC

Concerning...Heavy rainfall...Flash flooding possible

Valid 170430Z - 171000Z

SUMMARY...Intense rainfall rates peaking in the 2-3 in/hr range
are expected to continue affecting portions of eastern SC into
south-central/southeastern NC through 10Z. Additional flash
flooding is likely.

DISCUSSION...The 00Z RAOB from CHS showed 1640 J/kg MLCAPE,
embedded within a lingering pool of higher instability seen on RAP
analyses over coastal SC, with 1000 J/kg extending 50-100 miles
inland. KLTX radar from 04Z showed that an intense band of heavy
rain extended from Horry county in far eastern SC into Columbus
and Bladen counties of southeastern NC. Dual-pol estimates from
within this band peaked in the 2.5 to 3.5 in/hr range between
03-04Z, with at least one observation from Wunderground.com to the
southwest of Loris, SC...indicating 3 in/hr ending 03Z.
Precipitable water values remain high (2.1-2.4 inches per RAOB/GPS
data) despite having come down slightly from Saturday. Ample
instability and persistent low level convergent flow has been
supporting the long lived, semi-continuous heavy rain band from
far eastern SC into southern/southeastern NC for the past 6 hours.

As the low level circulation tied to Florence moves toward the
north-northwest through 12Z per recent RAP runs, the best axis of
low level convergence should also translate toward the
north/north-northwest which would mean disruption of the ongoing
axis of heavy rain in favor of redevelopment or translation toward
the north and/or northwest. Some recent development of convection
has been noted north of Florence, SC, but it is unclear if that is
the beginning of a new intense rain band or if the ongoing band of
heavy rain along the eastern SC/NC border will simply translate
north. Either way, locations in eastern SC into south-central to
southeastern NC are in an elevated risk area for 2-3 in/hr rain
rates through 10Z. Outside of the intense rain band over the SC/NC
border, continued periods of heavy rain with rates peaking in the
1-2 in/hr  range are expected. Given double digit rainfall over
the past couple of days for these locations, continued
major/catastrophic flooding/flash flooding ie expected.

Otto

ATTN...WFO...CAE...CHS...GSP...ILM...RAH...

ATTN...RFC...SERFC...

LAT...LON   36048050 35977977 35957916 35497864 34717834
            33837834 33517863 32807938 32717972 32957998
            33648013 33778017 34478065 35228073 35758066