Mesoscale Precipitation Discussion 0645
NWS Weather Prediction Center College Park MD
1122 PM EDT Sun Aug 12 2018

Areas affected...eastern NC

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

Valid 130319Z - 130830Z

Summary...Flash flooding will be possible across portions of
eastern NC through at least 09Z. 3-4 inches in 2-3 hours could
fall in a couple of locations.

Discussion...03Z regional radar imagery showed a small cluster of
thunderstorms producing KRAX estimated 1-2 in/hr rain rates over
south-central NC with an embedded mesoscale circulation over Hoke
county, tracking toward the east. Surface observations depicted a
slowly sagging outflow boundary just ahead of the small
thunderstorm cluster arcing from near OCW to just south of FAY.
Southwesterly 850 mb flow of roughly 10 kt was overrunning the
outflow with scattered thunderstorms located just north of the
outflow boundary. Despite fading with the onset of nocturnal
cooling, MLCAPE should remain sufficient to support heavy rainfall
rates with CAPE values increasing toward the east along with
stronger 850 mb flow of roughly 20 kt closer to the coast.

Southwesterly flow nearly parallel to the outflow boundary and
similar low level inflow/cloud-bearing winds may cause training of
heavy rain cores across portions of eastern NC as the ongoing
thunderstorm cluster over south-central NC continues to move east
over the next few hours. Precipitable water values near 2 inches,
remaining instability and upper support in the form of speed
divergence tied to a 70-90 kt speed max located over the northern
Mid-Atlantic region are expected to continue convection well into
the night. Beyond 06Z, additional convection is forecast by recent
runs of the HRRR to develop near the central and southern NC coast
which will have the potential to train and may combine with
activity propagating eastward from east-central NC allowing for
brief cell mergers. Given Flash Flood Guidance is generally 2.5 to
3.5 inches in 3 hours, flash flooding will be possible.

Otto

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

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

LAT...LON   36167677 36137609 35797537 35177529 34707586
            34467686 34417886 34797968 35477905 35957787