Mesoscale Precipitation Discussion 1003
NWS Weather Prediction Center College Park MD
1207 AM EDT Thu Nov 01 2018

Areas affected...Louisiana...Western MS...Far Southeast Arkansas

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

Valid 010406Z - 011006Z

Summary...Ongoing broken lines of convection will move into
portions of Louisiana...far western Mississippi...and far southern
Arkansas during the overnight hours. With an axis of instability
and high PWATs, convection will be capable of producing hourly
totals of 1-2" in a training environment which could lead to flash
flooding.

Discussion...GOES-16 water vapor imagery with 500 mb heights
showed strong vorticity maxima tracking across west-central Texas.
Ahead of this feature lies a broad area of upper level divergence.
The 00z LCH sounding depicted nearly unidirectional flow in the
low to mid levels, pumping Gulf moisture into the region. A recent
mesoanalysis showed PWATs around 1.9" which is around 2 SD above
the mean.

Recent radar trends show well established line of convection
moving across far southeast Texas and will push across much of
Louisiana into western Mississippi during the early morning hours.
Hourly rates of 1-2" have been observed per latest returns from
LZK, LCH, and HGX.

Through 10z, the latest run of HREF shows potential for areal
averages of 1-2" across central/southern LA and western MS. Some
hi-res members show potential for locally 3-4". The main limiting
factor for more widespread flash flooding issues to develop is the
1) forward speed of convection and 2) dry antecedent
conditions/higher FFG.

However, the intense hourly rates may overcome these factors and
lead to localized flash flooding concerns overnight. 

Taylor

ATTN...WFO...JAN...LCH...LIX...LZK...SHV...

ATTN...RFC...LMRFC...WGRFC...

LAT...LON   34079128 33489008 32638988 30968995 29609033
            29169090 29489217 29529275 29699368 31379347
            33449234