Mesoscale Precipitation Discussion 0549
NWS Weather Prediction Center College Park MD
223 PM EDT Sat Jul 28 2018

Areas affected...eastern NC

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

Valid 281822Z - 290020Z

SUMMARY...Thunderstorms with 3-5 inch rainfall potential are
expected to develop through the remainder of the afternoon and
continue into the evening over eastern NC. Flash flooding will be
possible, especially with overlap of these heavy rains with wet
antecedent conditions and/or locally sensitive areas.

DISCUSSION...At 18Z, visible satellite imagery showed the early
development of convection near and east of a stationary front
which extended from near ORF to just east of RDU to CAE. The
environment along and east of the front was fairly moist with
precipitable water values ranging from ~1.75 inches to the west,
to 2.25 inches along the coast. Wind shear is fairly weak with
cloud bearing mean flow of roughly 10-20 kt from the southwest and
area VAD wind plots at 850 showed 10-15 kt magnitudes at KRAX,
KMHX AND KTLX from the west to southwest.

Thunderstorms are expected to continue to expand over the next
couple of hours amid increasing CAPE values given mostly clear
skies across western portions of the Coastal Plain. Given the
generally weak low-mid level flow, limited organization of
individual cells is expected, but increasing coverage could lead
to an overall progression of storms toward the south. Cell mergers
and storm scale boundary collisions along with possible
interaction with an advancing sea breeze may cause locally very
heavy rainfall over a 1-2 hour period. Given many locations over
eastern NC have experienced over 300 percent of normal rainfall
over the last week so flash flood potential is locally a bit
higher than given a similar setup otherwise. Rainfall rates
between 2-3 in/hr overall are expected, lasting for 1-2 hours at
times.

Otto

ATTN...WFO...AKQ...ILM...MHX...RAH...

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

LAT...LON   36297691 36017555 35427528 34857548 34417655
            34157843 34737949 35877824