AWUS01 KWNH 222115
FFGMPD
TXZ000-230215-

Mesoscale Precipitation Discussion 0304
NWS Weather Prediction Center College Park MD
514 PM EDT Wed May 22 2024

Areas affected...west-central to central TX

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

Valid 222113Z - 230215Z

Summary...Thunderstorm will pose an isolated flash flood threat to
portions of west-central into central TX through 02Z. Rainfall
rates with areas of training and merging cells may exceed 2 in/hr,
producing spotty 3-5 inch totals through 02Z.

Discussion...Regional radar imagery at 21Z indicated widely
scattered thunderstorms including supercells just south of a cold
front and ahead of a dryline over central to west-central TX. The
environment across this region of TX, which includes the Hill
Country, was represented by impressive MLCAPE of 3000-5000 J/kg
with little to no CIN just ahead of the cold front and east of the
dryline but values of 50+ J/kg near San Antonio and parts of the
I-35 corridor via the 21Z SPC mesoanalysis. Precipitable water
values were 1.7 to 2.0 inches per recent GPS data and the 18Z FWD
sounding with plenty of shear for organized cells. Cell coverage
was expanding just north of the Colorado River across Coleman and
Brown into Mills counties with an average movement off toward the
east at 25-35 kt but with upstream regeneration promoting
MRMS-derived rainfall rates over 2 in/hr.

The recent expansion of cells over central TX and the potential
for cell training and merging of thunderstorms will carry the
potential for rainfall rates in excess of 2 inches in an hour or
less time over the next few hours. Little latitudinal movement of
the front is expected over the next few hours but cold pool
development and some further upstream convective development
anticipated in the direction of the triple point combined with the
general eastward cell movement will favor some isolated locations
with potential for 3-5 inch totals through 02Z. Flash flooding
will be possible, especially with overlap of sensitive terrain in
the Hill Country.

Otto

ATTN...WFO...EWX...FWD...MAF...SJT...

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

LAT...LON 32249880 32029699 30789661 30239796 30170001
30160124 30310223 30990157 31670147 32040059


= = =
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AWUS01 KWNH 051207
FFGMPD
TXZ000-051730-

Mesoscale Precipitation Discussion 0399
NWS Weather Prediction Center College Park MD
807 AM EDT Wed Jun 05 2024

Areas affected...Heart of Texas into Southeast Texas...

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

Valid 051215Z - 051730Z

SUMMARY...Rapidly weakening MCS with a few lingering over-running
thunderstorms capable of very intense rain rates and sub-hourly
rain totals of 1-3". Incidents of flash flooding are becoming
less likely with exception of urban areas and expansion/
reinundation of already flooded areas.

DISCUSSION...Regional RADAR mosaic and GOES-E 10.3um IR loop shows
a very broad decaying MCS with rapidly accelerating outflow
boundary bisecting LA from NE to WSW extending into southeast TX.
However, a few areas of remaining cold tops exist along the upwind
edge. This aligns with deeper moisture flux coming off the
Western Gulf coastal confluence axis that continues to stream
northward on 20-25kts of 925-850mb flow. Surface Tds are very
rich with mid to upper 70s dotted with an spot 80F dewpoint but
the q-axis remains from South Padre Island north through Victoria
into the upwind edge with 1.7" total PWats while further east are
sub 1.5". The instability axis is also further west of the q-axis
but still shows a greater intersection with the upwind edge; with
MLCAPE values of 3000+ J/kg. As such, the over-running and deep
moisture convergence in proximity to mature thunderstorms and
their associated cold pools aid toward maintenance of the
convective lines.

The lead line does appear to be slowing likely due to a shallowing
of the cold pool and increasing distance from the leading outflow
edge, and is probable to merge with the stronger wave over the
next few hours in the vicinity of Limestone/Falls to Houston
counties. Flux convergence will likely continue to support 2"+/hr
rates, though minus the timing of the merger, is likely to be
limited to a sub-hourly rain total and spots of 1.5-2.5" are more
likely the range of expected totals as the outflows/convergence
continues to surge southward into the moisture/instability axis
and eventually Gulf of Mexico. While these are quick hitters, that
will result in limited infiltration and increased run-off for
potential for flash flooding, especially in urban centers and
locations further north and east in eastern and southeastern TX
where grounds are already saturated/flooded.

Deeper layer steering of the deeper cells is becoming more west to
east in further distance from the MCV in AR, this may allow for
some increased duration too for repeating before the propagation
vectors dominate to the south, additionally supporting localized
maxima up to 2-3" in spots more likely over the next 1-3 hours.

Gallina

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

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

LAT...LON 32139658 32059595 31629499 31099427 30549382
29899393 29549447 29209518 29009578 29089679
29339731 29859779 30449799 31049800 31429783
31769756 31959731
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AWUS01 KWNH 191251
FFGMPD
TXZ000-191850-

Mesoscale Precipitation Discussion 0467
NWS Weather Prediction Center College Park MD
850 AM EDT Wed Jun 19 2024

Areas affected...South-Central to Southeast TX

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

Valid 191250Z - 191850Z

SUMMARY...The broken outer rainbands associated with Potential
Tropical Cyclone One will be arriving this morning across
south-central to southeast TX. Heavy rainfall rates and eventually
some concerns for training convection will support a gradually
increasing threat for flash flooding.

DISCUSSION...Potential Tropical Cyclone One remains situated down
over the southern Gulf of Mexico early this morning, but the
broken outer rainbands around the northwest flank of the system's
circulation are approaching the middle and lower TX coastlines and
will begin to move inland over the next several hours.

Cloud top temperatures in the GOES-E IR satellite imagery have
been tending to cool a bit overall over the last couple of hours
with the offshore activity, and this is largely be driven by
increasing low-level moisture flux convergence and instability
transport focusing along inverted surface trough. MLCAPE values
offshore over the western Gulf of Mexico are on the order of 1500
to 2500 J/kg, and with notable low-level speed convergence and
even frictional convergence near the coast, there will likely be
an increased level of convection becoming concentrated very close
to the coast and also just inland over the next several hours.

The environment is extremely moist around the northwest quadrant
of the system circulation, with PWs that are on the order of 2.4
to 2.6 inches based on early-morning GPS-derived data and the
latest CIRA-ALPW data shows highly concentrated moisture all the
way through the top of the vertical column. The very deep warm
cloud layer environment coupled with the instability transport and strengthening vertical ascent along the coast will support these
bands of convection producing extremely high rainfall rates that
should easily reach into the 2 to 3 inch/hour range, and may
approach 4 inches/hour for some of the stronger convective cells
by midday that will likely arrive once stronger instability begins
to overspread the coast.

Dry antecedent conditions will initially cut down on the flash
flooding risk, but over time, the arrival of heavier rainfall
rates and eventually cell-training concerns, should elevate the
flash flood threat. As depicted by the 06Z HREF consensus,
rainfall amounts going through early afternoon may reach 3 to 6
inches, and this will at a minimum support an urban flash flood
threat. Trends will be closely monitored over the next several
hours, and additional MPDs will be issued this afternoon
accordingly.

Orrison

ATTN...WFO...BRO...CRP...EWX...HGX...

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

LAT...LON 29459553 28979521 28499599 27799680 26799716
25779721 25699802 25969846 26839867 27859840
28639783 29289677
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AWUS01 KWNH 180935
FFGMPD
LAZ000-TXZ000-181400-

Mesoscale Precipitation Discussion 0647
NWS Weather Prediction Center College Park MD
534 AM EDT Thu Jul 18 2024

Areas affected...Hill Country of Texas east through the Piney
Woods

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

Valid 180934Z - 181400Z

Summary...A corridor of thunderstorms with heavy rainfall will
continue to drop southward through the morning along a nearly
stationary front. These thunderstorms will contain rainfall rates
of 2-3"/hr, which could produce locally more than 4" of rain.
Flash flooding is possible.

Discussion...The regional radar mosaic early this morning
indicates an expanding line of thunderstorms from far western
Louisiana through central Texas. These storms are developing along
a stationary front which should sag slowly southward as a weak
cold front later this morning. North of this boundary, a potent
shortwave noted in WV imagery and in SPC RAP Differential
Vorticity fields is spinning southward, enhancing lift in a region
already favorable through isentropic upglide of a modest LLJ and
beneath a subtle mid-level deformation axis. Thermodynamics across
Texas remain supportive of heavy rainfall, with PWs measured by
GPS of 1.9 to 2.1 inches collocated with MUCAPE exceeding 2000
J/kg. The overlap of ascent into this airmass is providing the
favorable conditions for increasing thunderstorm development, and
recent radar-estimated rain rates from KGRK WSR-88D have been as
high as 2.5"/hr.

The CAMs this morning all offer differing solutions to the
evolution of this convection, but while spatial coverage and
footprint vary, the intensity is well aligned among the various
models which increases confidence in a heavy rain event. The 850mb
LLJ is already beginning to slowly veer as noted in regional VWPs,
and is expected to become westerly by late morning. This will
limit the isentropic ascent and slowly reduce moisture transport
northward, but will also then become more aligned to the advancing
front, helping to turn the mean cloud-layer 0-6km winds parallel
to the front as well. Additionally, the propagation vectors will
become increasingly anti-parallel to the mean flow as the LLJ
veers, suggesting continued backbuilding of echoes to the SW and
along the front into the greater instability. With both HREF and
REFS probabilities for 2"/1hr accumulations reaching 40%, this
could result in 2-3" of rain along the boundary, with locally 4+"
possible as noted by the neighborhood probabilities. The
discussion area was drawn to somewhat emulate the EAS
probabilities which are highest across the Hill Country, Balcones
Escarpment, and along portions of I-35.

Recent rainfall across this region has generally been below normal
the last 7 days according to AHPS, but locally, NASA SPoRT 0-10cm
RSM is above 70%. This indicates that some infiltration of heavy
rain is likely, which is reflected by the higher FFG and
corresponding 3-hr FFG exceedance probabilities peaking at just
10-20%. However, the favorable setup for training of 2-3"/hr rain
rates could still overwhelm soils, especially in urban areas or
the across any more sensitivesoils, leading to rapid runoff and
instances of flash flooding.

Weiss

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

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

LAT...LON 31969389 31959322 31719285 30559369 30129502
29899686 29939839 30429957 30880043 31290077
31570017 31709930 31719830 31789713 31819532

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AWUS01 KWNH 031228
FFGMPD
TXZ000-031826-

Mesoscale Precipitation Discussion 0968
NWS Weather Prediction Center College Park MD
827 AM EDT Tue Sep 03 2024

Areas affected...much of Texas

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

Valid 031226Z - 031826Z

Summary...Areas of flash flooding are likely to continue through
at least the early afternoon hours (18Z/1p CDT).

Discussion...Much of Texas remains under the influence of broad
mid/upper difluence associated with a mid-leel wave over the
TransPecos. Additionally, low-level convergence continues in the
vicinity of a surface front subjectively analyzed from near JCT
eastward through central Louisiana near ESF. Across most of the
discussion area, the combination of 2+ inch PW values,
orographic/frontal confluence, weak inhibition, and at least 1000
J/kg MUCAPE was contributing to deep convection. The strongest
updrafts were located across the southern 1/3rd of Texas where
instability was strongest. Meanwhile, weak steering flow was
contributing to slow storm motions, and spots of 1-2.5 inch/hr
rain rates were occasionally observed - highest near deeper
convection across south Texas.

The ongoing scenario should continue to support scattered
instances of flash flooding throughout the day today. Further
compounding potential runoff issues are antecedent rainfall, which
has totaled 2-8 inches over the past 24 hours across broad parts
of Texas Midland to Abilene and in more localized spots near Del
Rio and along the Texas Coast. Areas of FFG exceedance are
expected throughout the day as deep convection lingers and
continues to result in spots of 1-2.5 inch/hr rain rates through
at least the early afternoon. In the near term, the greatest
concern for flash flood potential resides near Del Rio (where deep
convection was resulting in near 3 inch/hr rates over FFGs between
0.25-1.5 inch/hr) and across a large part of west-central Texas
where lighter rainfall continues and FFGs are between 0-1 inch/hr.

Slight risk areas are valid for much of the discussion area in the
D1 Excessive Rainfall Outlook, and expansions of that risk to
cover more of south Texas are anticipated at or before the 16Z
Outlook Update.

Cook

ATTN...WFO...CRP...EWX...FWD...HGX...LUB...MAF...OUN...SJT...

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

LAT...LON 33479778 33139704 32479689 31509744 30749750
30089734 29389646 28849589 27909632 27439733
27539951 28650052 29840109 31620133 33060056
33359945
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AWUS01 KWNH 041222
FFGMPD
TXZ000-041821-

Mesoscale Precipitation Discussion 0974
NWS Weather Prediction Center College Park MD
821 AM EDT Wed Sep 04 2024

Areas affected...south Texas through the middle Texas coast

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

Valid 041221Z - 041821Z

Summary...Persistent onshore flow was contributing to scattered
areas of heavy rainfall especially along coastal areas near Corpus
Christi. Isolated instances of flash flooding are expected to
continue through 18Z/1p CDT today.

Discussion...Deep, slow-moving convection continues to drift
onshore from northwestern Gulf of Mexico waters into the
discussion area. The onshore flow regime is being maintained due
to a weak surface low near Brownsville and east-southeasterly
850mb flow on the northeastern side of that cyclone. That
enhancement of low-level flow was maintaining strong buoyancy
(1500 J/kg MLCAPE) along and just inland from Texas coastal areas,
while low-level convergence was promoting continued updrafts amid
a very moist airmass (2.5+ inch PW values). This regime was
continuing to support local 1-3 inch/hr rain rates at times
especially with more persistent convection as noted with
convection near Port Aransas and just north of Brownsville.

The ongoing scenario supporting flash flooding will evolve very
slowly today. Spots of 1-3 inch/hr rain rates remain likely as
convection slowly streams westward toward Texas coastal areas
today. These heavier rain rates could also materialize as far
north as the Galveston area as well. FFG thresholds vary
spatially, and generally range from 1.5-3.5 inches/hr.
Isolated/localized flash flood potential is expected to persist
through at least 18Z today in this regime, with the most
pronounced threat existing where 1) >1 hour of heavier rainfall
persists and/or 2) in low-lying/sensitive areas.

Cook

ATTN...WFO...BRO...CRP...HGX...LCH...

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

LAT...LON 29899443 29479412 28739523 28229646 27159711
26169708 25819715 25769774 26399870 27419880
28479787 29529608
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