158
AWUS01 KWNH 141252
FFGMPD
MOZ000-ARZ000-141830-

Mesoscale Precipitation Discussion 0881
NWS Weather Prediction Center College Park MD
851 AM EDT Wed Aug 14 2024

Areas affected...Northwest/North-central MO to
North-central/Northeast AR...

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

Valid 141250Z - 141830Z

SUMMARY...A pair of mature warm advection induced MCSs are likely
to continue and merge over the next few hours.  Reducing
convergence should help to reduce coverage and intensity of
rainfall but a swath of 2-4" due to training may still pose
possible localized flash flooding through early afternoon.

DISCUSSION...GOES-E 10.3um shows a slowly decaying MCC with
increasingly more isolated overshooting tops to -80C across NE to
north-central MO with impressive outflow feathering of cirrus
along nearly all quadrants of the complex indicative of the
continued solid outflow and maintenance of the complex as it rolls
southeastward along the 500-1000 thickness gradient.   Downstream,
a more linear warm advection complex remains across south-central
MO into north-central and northeast AR.  Very cold tops with the
upstream edge continuing to develop/cool maintains solid potential
for heavy rainfall rates and training for flash flooding.   While
diurnal weakening of the MCSs is to be expected due to slacking
LLJ, current VWP trends are maintaining at 25-30kts of 850mb flow
perpendicular to the frontal zone still supporting solid
insentropic ascent and moisture convergence.

Veering with height even by 700mb shows steering remains NNW to
SSE becoming more due south into AR, at the northeast edge of the
synoptic ridge over TX/OK. This helps to concentrate enhanced
moisture up to 2.25" while also supporting a steering flow mainly
parallel to the ascent/convergence axis.   MUCAPE remains
sufficient at 1500-2000 J/kg along the western edge of the
complexes.  So rainfall efficiency will remain solid in the
2-2.5"/hr range.

The upstream MCC had generated a stronger cold pool and stronger
mid-level `dry-slot` jet that is mixing some increased momentum
air downward to advance southward propagation a bit faster.   WAA
along/ahead of the wave will help to fill in convective line
through central MO, but the upstream convective line will surge
southward effectively collecting the training axis across
south-central MO as long as the LLJ winds do not diminish too much
too quickly.  As such, an axis of 2-4" totals can be expected
across central to south-central MO and likely intersect areas
already experiencing flash flooding conditions as noted by MRMS
Flash with 200-600 cfs/smi.  As such, flash flooding is likely to
continue across that area.

Further south into northern AR, environmental parameters diverge a
bit with deeper layer flow/steering becomes a bit more divergent
through depth; moisture axis shifts eastward , while LLJ further
veers to more westerly supporting a more westward propagation
vector which also aligns with the instability axis further west.
This adds to a bit more uncertainty in placement and potential for
higher rainfall totals...but still intensity of rainfall over 2"
and spots of 3"+ still have solid potential for localized flash
flooding conditions through early afternoon as well.

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...EAX...LSX...LZK...MEG...SGF...

ATTN...RFC...ABRFC...LMRFC...MBRFC...NCRFC...NWC...

LAT...LON   40109349 39639225 38749149 36599130 35779028
            34959032 34669137 35029232 35909296 36689309
            37649339 38439381 38849424 39309465 39629478
            39999441