Mesoscale Precipitation Discussion 0688
NWS Weather Prediction Center College Park MD
1215 PM EDT Sat Aug 18 2018

Areas affected...Far southeast AR...Central MS

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

Valid 181615Z - 182015Z

Summary...Heavy showers and thunderstorms will continue over the
next few hours with some gradual expansion in coverage. Some
additional potential exists for flash flooding.

Discussion...The latest GOES-16 IR satellite imagery shows cooling
convective tops over areas of far southeast AR and across central
MS in association with a mid level trough that is seen digging
across portions of the lower MS and TN Valleys. The boundary layer
ahead of the trough axis is becoming increasingly unstable with
MLCAPE of 1500+ j/kg and this should foster a bit more convective
organization and coverage going through the early to mid afternoon
hours.

PWATS across the region are quite high and on the order of about
2.25 inches. This will favor extremely heavy rainfall rates that
may approach 3 inches/hr in some cases given efficient rainfall
processes and the strengthening thermodynamic profiles.

The latest 12Z hires model consensus favors as much as 3 to 4
inches going through mid-afternoon, and gradually the signal for
heavy rainfall will become more focused farther to south across
areas of southern MS by later this afternoon.

Many areas of southeast AR and central MS saw heavy rain
yesterday, and thus given the relatively wet antecedent
conditions, the additional rainfall will foster concerns for some
additional flash flooding.

Orrison

ATTN...WFO...BMX...JAN...LZK...MEG...

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

LAT...LON   33959099 33959045 33748965 33478886 32828833
            32038877 32139015 32619125 33129178 33759165