Mesoscale Precipitation Discussion 0820
NWS Weather Prediction Center College Park MD
916 PM EDT Mon Sep 10 2018

Areas affected...South Central SC...East Central GA...

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

Valid 110115Z - 110515Z

SUMMARY...Nearly stationary, slight backbuilding/repeat highly
efficient cells may produce isolated flash flooding.

DISCUSSION...Surface analysis and 850mb VWP/RAOB suite, suggest a
weak surface to boundary layer wave in east central GA just NE of
MLJ.  While winds are weak, the inflection has allowed for
increased moisture and mass piling to sprout convection.  The
piling supports increase of local moisture with sfc Tds in the mid
to upper 70s near AGS to CAE, and total PWATs in the 2.25" range
(and mid-levels at around 90% RH).  This suggests highly efficient
rainfall processes with rates of 2.5"/hr likely. 

The confluence is located in weak mid-level steering flow
supporting near zero cell motions to the northeast countered by
propagation vectors equally weak but opposite supporting
chaotic/stationary cells. So with modest unobstructed/cooled
inflow from the south cells could hang around for 2-3 hours. 
While the FFG values are very high, these rates in short duration
may be close enough to support possible flash flooding conditions,
especially given proximity to urban centers along I-20 between
Augusta and Columbia. 

Gallina

ATTN...WFO...CAE...CHS...FFC...GSP...

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

LAT...LON   34378110 34118042 33718037 33308092 33088150
            32968199 33018276 33208297 33578299 33998253
            34158184