Mesoscale Precipitation Discussion 0627
NWS Weather Prediction Center College Park MD
327 PM EDT Fri Aug 10 2018

Areas affected...Southern MS & Eastern LA

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

Valid 101925Z - 110025Z

Summary...Thunderstorms within a zone of low-level convergence
should allow for hourly rain totals to 2.5" with local amounts to
4" over the next five hours.

Discussion...Thunderstorms are forming within a zone of 850 hPa
convergence in a divergent environment aloft between an upper low
near the Lower Ohio Valley, an upper low in the eastern Gulf, and
a small upper level disturbance offshore southern LA. 
Precipitable water values of 2-2.25" lie here per GPS data. 
Inflow is generally out of the west-northwest at 15 kts.  ML CAPE
values of 2000-2500 J/kg lie across the area.

While convection is expected to remain pulse due to a lack of
effective bulk shear, the degree of instability and low-level
convergence could yield heavy rainfall from east-central LA into
southeast LA and southern MS.  The mesoscale guidance has a
reasonable signal for heavy rain, generally showing local amounts
of 4" over the next five hours.  The available instability should
allow convection to thrive for 4-5 hours, which is also reflected
in the 12z HREF probabilities of 1"+ in an hour.  Where cells
collide or briefly train, hourly rain totals to 2.5" are possible.

Roth

ATTN...WFO...JAN...LCH...LIX...MOB...SHV...

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

LAT...LON   31498942 31088826 30388830 30238974 30739207
            30889234 31389220 31399117 31429031