AWUS01 KWNH 030902
FFGMPD
LAZ000-TXZ000-031501-

Mesoscale Precipitation Discussion 0213
NWS Weather Prediction Center College Park MD
502 AM EDT Fri May 03 2024

Areas affected...southeast Texas

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

Valid 030901Z - 031501Z

Summary...Deepening convection is forming in areas that received
abundant rainfall yesterday. Sensitive ground conditions will
likely promote additional runoff and flash flood concerns through
15Z today.

Discussion...Renewed development of convection was ongoing in
earnest this morning generally from Bryan/College Station
east-southeastward through Gulf waters just south of Cameron, LA
over the past hour or so. These storms were developing along
remnant outflow from prior convection yesterday morning, with
subtle 850mb confluence aiding updrafts amid 1500-2000 J/kg MLCAPE
and abundant moisture (1.8 inch PW). Unfortunately,
east-northeasterly storm motions were fostering movement of
convection into areas of southeast Texas that received abundant
(2-7 inch) rainfall totals from yesterday, with ongoing
flood/flash flood impacts continuing. The renewed convective
development is likely to worsen ongoing flooding and cause new
flash flooding in at least a few areas across southeast Texas
through the morning.

Models/observations suggest that convection will persist across
the discussion area through at least 15Z, with areas of 1-1.5
inch/hr rain rates materializing as convection deepens and
matures. Localized areas of cell mergers could prolong rain rates
in a few spots as well. FFGs are quite low (0.25-1 inch/hr
thresholds), further highlighting the sensitivity of the ground
conditions across the discussion area. Flash flooding is likely
in this regime.

Cook

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

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

LAT...LON 31239501 31069405 30499324 30019309 29689339
29499411 29629501 29799611 30079670 30489671
30859634 31209564

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AWUS01 KWNH 051329
FFGMPD
TXZ000-051800-

Mesoscale Precipitation Discussion 0228
NWS Weather Prediction Center College Park MD
929 AM EDT Sun May 05 2024

Areas affected...Portions of Southeast Texas

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

Valid 051328Z - 051800Z

SUMMARY...Flash flooding likely as storms developing along a
boundary west of Houston track along the boundary over
hydrologically sensitive areas west of Houston and into the
Houston Metro. Considerable urban flash flooding potential is
increasing.

DISCUSSION...Training convection developing west of Houston is
moving east towards Houston this morning. The storms have formed
along an outflow boundary that was set by the MCS that is
departing off to the east. CAMs guidance suggests the boundary
will remain nearly stationary through the day. Abundant Gulf
moisture moving in from the Gulf will continue to feed moisture
and instability into the storms through midday. Thus, the
potential for significant, considerable, and high-impact urban
flash flooding is increasing.

CAMs guidance remains in poor agreement on how this boundary will
behave through the day today. Much of the guidance is much further
south with the boundary than where it has actually developed.
However, they are in better agreement that the boundary convection
will not only continue to develop, but gradually backbuild west to
as far as the Rio Grande. Should that occur a follow-up MPD may be
needed. For now, the area of concern remains for portions of
Southeast Texas, as regardless of how far west the convection
develops later, storms are likely to continue in the highlighted
area.

Wegman

ATTN...WFO...EWX...HGX...

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

LAT...LON 30299528 30279493 29879455 29419472 29279486
29179521 28919548 28869636 29179688 29339743
29749751 30129726 30159733 30259708 30249631
30259575

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AWUS01 KWNH 161145
FFGMPD
TXZ000-161730-

Mesoscale Precipitation Discussion 0272
NWS Weather Prediction Center College Park MD
744 AM EDT Thu May 16 2024

Areas affected...North Texas into the Rolling Plains

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

Valid 161143Z - 161730Z

Summary...Clusters of showers and thunderstorms will expand
through the morning while diving southeast through northern parts
of Texas. Rainfall rates of 1-2"/hr will be common, which could
result in 2-3" of rainfall. Flash flooding is possible.

Discussion...The GOES-E IR imagery this morning indicates an
expanding area of cooling cloud tops across western OK and into
northern TX, with temperatures within the most intense updrafts
falling to nearly -70C. Trends in the satellite suggest cloud tops
are cooling more rapidly than earlier, which is indicative of the
strengthening convection noted via the regional radar mosaic.
These thunderstorms are forming in the vicinity of a surface low
along a stationary front analyzed by WPC, with favorable low-level
convergence aiding the ascent. Rainfall rates within this
deepening convection have been estimated via KFWS WSR-88D to be
above 1"/hr, and although mesonet observations indicate limited
total rainfall so far, it is likely intensity and accumulations
will ramp up through the morning.

As this cluster sinks southeast, it will encounter a more
favorable environment for intensification. The 850mb LLJ is
progged to remain 25-35 kts, originating from an area of SBCAPE
above 3000 J/kg accompanied by PWs in excess of 1.75 inches. This
overlap of moisture and instability will surge northward on this
LLJ, enhancing the already favorable thermodynamics, and
converging along the nose of the jet into the elevated front to
provide additional ascent. At the same time, broad divergence
downstream of a mid-trough pivoting across NM will combine with
the LFQ of a jet streak rotating through the base of this trough
to drive pronounced synoptic ascent, and this should fuel an
expansion and intensification of convection. Although high-res
models are struggling to initialize current activity, there is
good agreement that thunderstorms will surge southward while
organizing and expanding in response to 25-45 kts of bulk shear
and impressive elevated WAA. The convection may generally remain
progressive, especially along the elevated front, but the
combination cold pool/stationary front sagging southeast may
permit some training back to the SW, enhancing at times the
duration of the 1-2"/hr rain rates. This will result in locally as
much as 3" of rain as reflected by HREF probabilities reaching
20-30% in the next 6 hours.

40cm soil moisture according to NASA SPoRT is above the 90th, and
even 95th, percentile in many areas due to recent heavy rainfall.
This suggests that despite FFG that has recovered to 2-2.5"/3hrs,
which has only a 10-20% chance of exceedance according to the
HREF, these soils are likely hydrophobic which could result in
rapid runoff leading to at least isolated instances of flash
flooding. The greatest risk for this will be across less
permeable/urban areas, or atop the most saturated soils.


Weiss

ATTN...WFO...FWD...LUB...MAF...OUN...SJT...

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

LAT...LON 33649831 33519766 33129703 32649662 32259649
31819665 31749746 31739803 31529885 31319948
31050010 31050074 31210113 31460126 32140101
33119998 33519901

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