Mesoscale Precipitation Discussion 0856
NWS Weather Prediction Center College Park MD
605 AM EDT Mon Sep 17 2018

Areas affected...central/eastern NC into central VA

Concerning...Heavy rainfall...Flash flooding likely

Valid 171004Z - 171600Z

SUMMARY...Intense rainfall rates peaking in the 1.5-2.5 in/hr
range are expected to affect portions of central/eastern NC into
central VA through 15Z. Possible training heavy rain could also
move into the coastal SC/NC border over the next few hours.
Additional flash flooding is likely for northern regions, with
possible flash flooding over eastern SC/southern NC.

DISCUSSION...Radar imagery at 0930Z showed 2-3 relatively narrow
axes of training heavy rainfall over central NC, focused within
low level confluent flow well east of the low level circulation
associated with Tropical Depression Florence. KRAX rainfall rates
were 1.5-2.5 in/hr within these bands and appeared to be reliable
given a report near I-40 east of Clinton, NC ending 08Z of 2.5
in/hr...near KRAX estimates. The SPC mesoanalysis page showed
MLCAPE of 500-1500 J/kg over south-central NC at 09Z, a 200-400
J/kg rise over the past 3 hours.

As the 850 mb low tied to Florence over eastern KY continues to
move to the NNE, low level bands of confluence are forecast to
slowly shift northward into portions of central VA. Southerly
850-700 mb flow will continue to push moisture toward the north
over the next 3-6 hours, along with steadily increasing
instability. Aloft, flow is diffluent with an upper level
anticyclone centered over the NC coast, and southerly flow over
the Appalachians ahead of an upper level trough axis located over
the lower Ohio Valley.

Farther south, radar imagery showed intense convection offshore of
southern SC as of 0930Z. This area also lies within an axis of 850
mb confluence/convergence which weakly extends northward toward
the coast. There is some potential for this axis of heavy rain to
expand north into far eastern SC and southeastern NC where heavy
rain has plagued the region over the past 24-48 hours. Rain rates
of 1-2 in/hr will be possible along with flash flooding.

Otto

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

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

LAT...LON   38277831 38037761 36897740 35547752 34257805
            32827863 32577900 32837924 33757930 34387919
            34647933 34717963 34607989 34608022 34778046
            35048047 35688028 36567984 37317938 37717903