Mesoscale Precipitation Discussion 0100
NWS Weather Prediction Center College Park MD
953 PM EDT Thu Mar 14 2024

Areas affected...Northeast TX...Southeast OK...Arkansas...Eastern
TN...Northern MS...

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

Valid 150155Z - 150730Z

SUMMARY...Expanding linear convective complex favorably oriented
to the deep layer steering flow will allow for areas of intense
rainfall rates over 2"/hr and streaks of 3-5" resulting in likely
incidents of flash flooding across Northeast TX into Western TN
overnight.

DISCUSSION...GOES-E 10.3um showing a cooling and expanding
convective complex from the Red River of SE OK and NE TX across AR
nosing toward W TN at this time.  Internally, numerous
overshooting tops dotting the center of the complex with -70C
indicating maturing/strong updrafts within the favorably unstable
environment across the warm sector.  To exacerbate the issue,
orientation of the overshooting tops denote the growing concern
for favorable mergers and training cells; this is related to the
exiting of a mid-level shortwave/mature MCV racing across the
Mid-Mississippi Valley into S IL.  As a result, the associated
meso-high blow echo is orienting the outflow boundary toward the
strengthening southwesterly LLJ and southerly/nearly orthogonal
surface flux across central AR.  Ample low level moisture with Tds
in the upper 60s to low 70s with modestly steep mid-level lapse
rates results in ample unstable air with CAPE values still in the
2000-3000 J/kg range (even in an elevated nature).

As such, strong moisture flux/strong updrafts (as noted by the
instability and overshooting tops) suggest increasing moisture
flux and rainfall efficiency, with hourly rates up to 2"/hr in the
cores, though 15-minute rainfall totals of 1-1.3" are likely given
00z HRRR and additive WoFS totals.  While a mid-level jet is
translating over the top of the complex now, increasing cell
motions, but as noted, weak inflection lifting northeast through
the flow should allow for some timing (2-4hrs) of favorable
training orientation before weak height-falls and right entrance
upper level dynamics allows for some forward (southeast)
propagation of the line/complex after 07z).   As a result, of the
efficient rain and training, streaks of training cells mainly out
of SE OK across central AR will allow for streaks of 3-5" totals
and continue likely flash flooding...given the longer duration
potential there.

However, other streaks further downstream into W TN/NW MS as well
as favorable upstream/back-building near the nose of the
EML/Western Gulf LLJ confluence across NE TX, may support similar
rates but shorter duration for spots of 2-4" and possible
incidents of flash flooding as well.

Gallina

ATTN...WFO...FWD...JAN...LZK...MEG...OHX...OUN...SHV...TSA...

ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC...

LAT...LON   36338831 36068758 35368774 33959029 32469541
            32719744 33869742 35309502 35949260 36249043