Mesoscale Precipitation Discussion 0852...Corrected
NWS Weather Prediction Center College Park MD
509 PM EDT Sun Sep 16 2018

Corrected for Flash Flooding Likely in Concerning Line

Areas affected...Western NC...Ext Eastern TN...Southwest VA...

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

Valid 162100Z - 170300Z

SUMMARY...Strong moisture flux and persistent orographic ascent to
lead to 3-4" totals in next 6hrs in complex terrain, leading to
likely flash flooding. 

DISCUSSION...Analysis places surface to 850mb low lifting NW
across Upstate SC, however, strong height-falls associated with
mid-level center near Charlotte, NC is tightening and enhancing
confluent moisture flux across central NC.  As such 850mb flow is
surging around 50-55kt from the due east into the terrain of
western NC with over 1.25" inches of precipitable water (per CIRA
LPW sfc-850mb layer) continuing.   In the next few hours, the
confluent bands near the apex of the wave will surge northwest and
850mb winds will veer sightly to orient more perpendicular to NW
NC mountains and support up to 1"/hr rates and totals of 3-4". 
Further south, in SW NC...weak damning sfc NE winds will slacken
and turn more easterly and mid-level dry (drier) slot should
rotate through and reduce orographic ascent and moisture
flux...but an additional 1.5-2.5" is likely to continue flash
flooding threat there as well.

RAP analysis suggests relatively clear air across central VA has
supported increased instability with MUCAPEs of 500-1000 noted and
surface T to 80 and Tds in mid-70s. This is currently being
advected 925-850mb) into the SW VA and likely to enhance showers
with perhaps isolated embedded convective elements, further
suggesting increased rain rates/totals and likely flash flooding
this evening into tonight. 

Gallina

ATTN...WFO...GSP...MRX...RAH...RNK...

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

LAT...LON   37997952 37547902 37127914 36377978 36008043
            35308141 35238265 35538332 35648339 36268318
            36878212 37548085 37948002