Mesoscale Precipitation Discussion 0703...Corrected
NWS Weather Prediction Center College Park MD
742 PM EDT Mon Aug 20 2018

Corrected for repetition in the last line

Areas affected...NC

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

Valid 202336Z - 210406Z

Summary...Showers and thunderstorms are developing over an area
with recent heavy rainfall.  Hourly rain totals to 2.5" with local
amounts to 4" are possible through 04z.

Discussion...A boundary across NC has been acting as a focus for
showers and thunderstorms over the past couple hours.  Some of the
thunderstorms are aligning into a band ahead of what appears to be
a mesocyclone moving out of western NC.  Precipitable water values
are 1.75-2.25".  ML CAPE values of 2000-2500 J/kg exist in this
region.  Effective bulk shear of 20-30 kts is helping to organize
thunderstorm activity.  The flow aloft is divergent in the wake of
an upper level low moving out into the western Atlantic, with an
apparent jet streak punching down from central VA into northern NC
per water vapor imagery.

The mesoscale guidance shows a scattershot signal of local amounts
in the 3-4" range over the next several hours.  The 18z HREF
probabilities of 1"+ an hour begin to relent beyond 04z, which
defined the time horizon of the MPD.  Given the available
moisture, 2.5" an hour rates are possible where cell merge, train,
backbuild, or where mesocyclones appear.  There is special concern
in NC as conditions have been wet lately, with pockets of 3-5" of
rain during the past couple days and two week precipitation
anomalies showing pockets of 200-300% of normal.  Given the
organized nature of some of the thunderstorm activity and the
partially saturated conditions, flash flooding is considered
possible. 

RotER

ATTN...WFO...AKQ...GSP...ILM...MHX...RAH...RNK...

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

LAT...LON   36358066 36237779 36097641 35427661 35037699
            34667782 34857968 35368032 36338147