BBS: TELESC.NET.BR
Assunto: MESO: Nws Weather Prediction Center College Park Md
De: COD Weather Processor
Data: Wed, 27 May 2026 06:11:36 +0000
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AWUS01 KWNH 270611
FFGMPD
TXZ000-271200-
Mesoscale Precipitation Discussion 0254
NWS Weather Prediction Center College Park MD
210 AM EDT Wed May 27 2026
Areas affected...South Texas...
Concerning...Heavy rainfall...Flash flooding likely
Valid 270610Z - 271200Z
SUMMARY...Flattening squall line with upstream deepening wave,
likely to result in expanding convective environment with ample
training/repeating opportunities and likely result in 3-5" totals
DISCUSSION...Regional RADAR shows mature progressive squall line
crossing along I-10 through the central Texas Coastal Plain with
the anti-cyclonic rotor of the squall resulting in a flattening
west to east outflow boundary across south-central to southern
Texas. A strong, broad super-cell anchors the base of the line
with overshooting tops colder than -80C. Surface and VWP show
southeasterly veering to southerly at 15-20kts and 35-40kts,
respectively intersecting this boundary, leading to strong
isentropic ascent. The advected air remains very unstable with
MLCAPEs of 3500-4000 J/kg with mid to upper 70s Tds; resulting in
strong to extreme moisture flux convergence 20+ kg/m/s.
GOES-E WV suite notes and upstream speed max in the sub-tropical
jet is dipping the orientation ever so slightly to support
diffluence aloft, which is also aiding development of an embedded
shortwave feature near 27.5N102W, leading to a new convective
cluster over the Sierra Madre, still fairly displaced from the
deeper surface to 850mb moisture. However, CIRA LPW does note
that downstream of the wave, cross Mexican 850-700 and 700-500
moisture connection intersects over the Lower Rio Grande Valley to
support 2-2.25" total PWats. The combination of the approaching
upper-level forcing with the isentropical ascent/convergence is
likely to fill in the line between the upstream cluster and the
tail of the squall. Strength of updrafts and flux convergence
will support very intense sub-hourly burst, but hourly
rates/totals of 2-3" are probable along the axis due to deep layer
steering supporting repeating/training environment. There remains
some uncertainty to the vigor of the cold pool generation and
therefore the propagation vectors are wavering between due east
and southeast within the Hi-Res CAM guidance suite. No deviation
may result in the most extreme totals from Webb to San Patricio
county with localized spots in excess of 6-7" by 12z; while more
deviation to the southeast will broaden the overall heavy rainfall
coverage to 3-4" areal expectations.=20=20
While FFG values are naturally high, the shear moisture flux and
rates with any increased residency, which looks very likely, will
result in flash flooding conditions; if duration would to align
with urban locations, such as Corpus Christi; inundation flooding
could be considerable.
Gallina
...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!8O3XZqK8S-30Y47xAsJel_YCB0ORWKjuTdXMYWfd5selvNjk3eIZe_hUkWhezQJ550KM=
pa2ekzjYHR9GcOuMyDMn5Qw$ for graphic product...
ATTN...WFO...BRO...CRP...EWX...
ATTN...RFC...FWR...NWC...
LAT...LON 29029723 28579667 28179654 27659707 26889741=20
26759840 26999955 28430046 28889905=20
=3D =3D =3D
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