Mesoscale Precipitation Discussion 886
NWS Weather Prediction Center College Park MD
1202 AM EDT Sun Sep 23 2018

Areas affected...South-central VA and north-central NC

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

Valid 230401Z - 231001Z

Summary...Slow-moving showers and thunderstorms will continue to
develop and focus along and to the north of a stationary fronts. 
Periods of training convection are likely and this could lead to
additional instances of flash flooding.

Discussion...Regional Doppler radar imagery depicts numerous
slow-moving showers and thunderstorms near the North
Carolina-Virginia border.  The convection has been focusing just
north of a quasi-stationary front with considerable over-running
of low level moisture over this boundary.  The latest SPC
mesoanalysis is indicating MUCAPE on the order of 500 to 750 J/kg
over this region. Ascent is also being aided by modest right
entrance upper jet dynamics and a weak shortwave approaching the
southern Appalachians.

The PWs across the region remain nearly 2 standard deviations
above normal with values approaching 1.75 inches, and this will be
conducive to highly efficient rainfall processes given the focused
moisture convergence.  Recent high res model runs vary in their
placement of the highest QPF maxima, with the HRRR and ARW having
a good depiction based on current radar trends.  The WRF, NAM, and
ECMWF appear to be displaced too far north with the main QPF axis.
 Rainfall amounts of 2 to locally 4 inches will be possible
through 10Z, which may cause some additional flash flooding given
the overall wet antecedent conditions.

D. Hamrick

ATTN...WFO...AKQ...LWX...RAH...RNK...

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

LAT...LON   38137882 38087798 38057733 37967690 37737658
            37437618 37047599 36497578 36267592 36157633
            36197736 36257858 36187946 36047994 36278030
            36558055 37168074 37658052 37988014 38127962