AWUS01 KWNH 201324

FFGMPD

LAZ000-TXZ000-201730-



Mesoscale Precipitation Discussion 0479

NWS Weather Prediction Center College Park MD

923 AM EDT Sat Jun 20 2026



Areas affected...Eastern Texas and Southwest Louisiana



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



Valid 201322Z - 201730Z



Summary...Clusters of showers and thunderstorms will gradually

sink southeast this morning with rainfall rates of 2-3"/hr. This

will continue the ongoing flash flood risk for a few more hours.



Discussion...The regional radar mosaic early this morning shows a

small cluster of thunderstorms in the vicinity of Waco, TX and

extending east towards LA. This cluster is moving slowly E/SE, and

is being driven by a potent shortwave noted in the GOES-E WV

imagery, with an attendant MCV likely in place as well based on

circulation evident in reflectivity. Rainfall rates within this

cluster have been measured by MRMS to be more than 2"/hr, and

several mesonet sites across Limestone and Leon counties have

received 4-5" of rain so far this morning.



As the shortwave/MCV track slowly southeast the next few hours,

they will encounter extremely favorable thermodynamics to continue

to support heavy rainfall. PWs as measured by GPS are well over 2

inches, with accompanying MUCAPE approaching 3000 J/kg. Broad

troughing aloft (within which this shortwave is embedded) will

additionally support ascent, so even though the LLJ is progged to

gradually veer, weakening the thermodynamic advection, there

should still be sufficient thermodynamics and kinematics for this

cluster to persist. This is reflected by several more hours of

robust simulated reflectivity in high-res guidance, as well as

only a slow wane in elevated (>50%) probabilities for at least

1"/hr rainfall rates. This will support additional rainfall of

2-4" of rainfall (40-60% chance of at least 3" in the next 6

hours) across portions of eastern Texas including the eastern

Texas Triangle and the Piney Woods, leading to isolated to

scattered instances of flash flooding through the remainder of the

morning hours.



As this cluster begins to decay, secondary development may occur

farther southeast as the shortwave continues to dive southward and

a bay breeze develops. There is more uncertainty into this

development at this time, but high-res guidance and accompanying

probabilistic information suggest slow moving storms may develop

as early as 15Z from near Houston, TX through SW LA, with

additional heavy rain rates fueled by rich theta-e air lifting off

the Gulf. Storm motions along this boundary may just be around 5

kts and parallel to the boundary, suggesting an increasing flash

flood risk due to training cells leading to 2-4" of rainfall atop

saturated soils.





Weiss



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



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



ATTN...RFC...FWR...ORN...NWC...



LAT...LON   32299545 32109451 31939424 31619356 31289286 

            30859224 30499205 30229217 30009288 29619391 

            29469427 29299481 29299516 29339549 29489579 

            29729609 30009645 30519675 31209698 31839704 

            32289644