AWUS01 KWNH 261642
FFGMPD
TXZ000-262230-

Mesoscale Precipitation Discussion 1192
NWS Weather Prediction Center College Park MD
1141 AM EST Thu Dec 26 2024

Areas affected...East Central and Southeast Texas...

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

Valid 261645Z - 262230Z

SUMMARY...Increasing convection is developing along confluence
lines within the strengthening warm conveyor belt.  Upstream
moisture flux/instability advection likely to aid in storm-scale
backbuilding resulting in periods of training.  Rates increasing
from 1.25 toward 2"/hr by 21z will allow for localized spots of
2-4" in the next 6 hours.  Localized flash flooding will be
possible.

DISCUSSION...A highly dynamic setup is trying to rapidly evolve an
strengthening thermodynamic environment conducive of strong
thunderstorms with intense rainfall potential for this evening.=20
However, in the interim, smaller pockets of unstable air and
strong dynamic ascent patterns will produce widely scattered cells
that will have the capability of producing locally 2-4" totals by
22z and may induce localized flash flooding.

GOES-E WV suite shows a highly amplified upper level pattern with
dual jets flanking a weakly negative tilt orientation across the
Red River Valley into central TX; the upstream jet across E NM is
about 110-120kts decelerating and descending across the Hill
country before rounding the base and entering a broad
strengthening 100 kt jet entance across much of central TX into E
OK, though broader diffluence is supportive of divergence aloft
across the Mid-Texas Gulf Coast into SE TX. attm.  The old
stationary boundary extends from near Ardmore to west of DFW metro
toward Austin and just west of BEA/NOG under influence of the
highly unstable western Gulf of Mexico.  The strengthening LLJ
aligns with the natural confluence of the western Gulf and is
surging deeper moisture/instability along a rising warm coastal
front through the Coastal Plain at this time; intersecting with
the old surface boundary near KT20.  This LLJ will act as a solid
warm conveyor belt with embedded N-S confluence lines until the
main upper-level height-falls and effective mid-level cold front
presses south and eastward into the evening hours.  The building
heat from slightly clearing skies has brought temps in the low 70s
with similar high 60s and low 70s Tds and increasing MLCAPEs to
1500-2000 J/kg with the warm front.  Convergence from
southeasterly surface low should provide sufficient convergence
for scattered thunderstorm development.  Recent Lightningcast
products have been rapidly increasing signals throughout the warm
sector with a few cells even further north into east-central TX;
with expected further expansion with further surface
heating/instability growth.

Cells that do develop will be ingesting solid 1.25-1.5" total PWat
air within 30-35kt increasingly confluent flow, which should
support back-building environment.  Given the 850-700mb warm
sector low-level shear profiles will support solid bulk shear
values for organized updrafts with some rotation, further
increasing moisture flux convergence and loading in the lower
profile for efficient rainfall production.  Rates of 1.25"/hr will
increase to near 2"/hr over the next 6 hours and while coverage is
likely to be more scattered in nature initially, the backbuilding
and favorable orientation of convergence bands to the mean
steering will allow for short-term periods of localized training
to allow for some localized spots of 2-4"; with greater
probability initially closer to the coast and along the rising
warm front.  This may intersect areas that received 2-4" of rain
two days ago, as NASA SPoRT 0-40cm soil saturation ratios are
modestly high particularly north and east of the Houston Metro,
but there were some spots southwest that show 200-400% above
normal precip anomalies on AHPS.  With all this considered
scattered incidents of flash flooding are considered possible
before evening but will be increasing with time (and after 22z)
across the area of concern.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!83k89vQkL0se-6SxlNfGWD-VH7qKLS8PCzmL9AIX5ULv-DJljqIl3izLKVzxx1HlQKCv=
ZErtIX9-PAavlPWwysaZmIk$  for graphic product...

ATTN...WFO...CRP...EWX...FWD...HGX...LCH...SHV...

ATTN...RFC...WGRFC...NWC...

LAT...LON   32249475 31939413 31449382 31059379 30229390=20
            29509439 28239651 28449693 29519697 30789716=20
            31529678 31979601 32219541=20

=3D =3D =3D
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