Mesoscale Precipitation Discussion 0988
NWS Weather Prediction Center College Park MD
754 AM EDT Tue Oct 16 2018

Areas affected...In and near Central MS

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

Valid 161154Z - 161803Z

Summary...A moist airmass with limited, but slightly growing,
instability, should be able to foster hourly rain totals to 1"
with local amounts of 3-4" through 18z.

Discussion...An elevated slice of a warm front (near 850 hPa)
returning across southeast LA and southern MS combined with the
eastern branch of the low-level jet is leading to fresh convection
in an near central MS at this time.  Precipitable water values are
~1.75" per GPS data.  MU CAPE values of ~200 J/kg lies here per
SPC mesoanalyses, which has slightly grown as of late.  Effective
bulk shear is 30-40 kts, which along with fairly unidirectional
flow with height appears to be organizing activity into a band
which has shown occasional backbuilding character to the south.

Most of the mesoscale guidance is having issues with this band,
with the 00z WRF NSSL doing rather well.  As precipitable water
values are forecast to eclipse 2" and MU CAPE should at least hold
its own, ~60% of the PW value should be realized as an hourly rain
total, which has occurred overnight to the west across northwest
LA and portions of TX.  The 00z WRF NSSL advertises local amounts
of 3-4" which could occur in a few hours and challenge the recent
flash flood guidance values despite dryness over the past couple
weeks.  Issues are most likely in urbanized areas.

Roth

ATTN...WFO...BMX...JAN...MEG...SHV...

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

LAT...LON   34008769 33548627 32648890 32209212 32959154