602
AWUS01 KWNH 231717
FFGMPD
TXZ000-232016-

Mesoscale Precipitation Discussion 0307
NWS Weather Prediction Center College Park MD
116 PM EDT Thu May 23 2024

Areas affected...Texas Hill Country

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

Valid 231716Z - 232016Z

Summary...A localized area of backbuilding storms has materialized
across the Texas Hill Country. Additional backbuilding will
support a localized corridor of flash flooding through the next
few hours.

Discussion...Radar continues to track a focused corridor of slow
moving thunderstorms across the Texas Hill Country between KGRK
and KDYX. Rainfall rates upwards of 2-3 inches were estimated by
recent MRMS scans and KGRK, although some hail contamination may
be present. Over the last 30 minutes, the backbuilding nature of
these storms combined with intense rainfall rates led to a quick
uptick in CREST Unit Streamflows upwards of 200-400 cfs/smi.

The mesoscale environment around this activity will remain quite
favorable to maintain some backbuilding organized deep convection
for at least a few more hours. Recent GPS data indicated PWATS
near the inflow region of these storms were around 1.70-1.9", with
steep 8 degree mid-level lapse rates available to foster extreme
instability (3000-4000+ J/kg MUCAPE) for this convection to tap
into. Effective shear upwards of 50-60 kts across Central Texas
will also maintain supercellular storm profiles, with slow Bunkers
storm motions of 10-15 kts noted to enhance longevity of rainfall.


Through the next several hours, the threat of localized
backbuilding slow moving storms will continue as aggressive
destabilization continues upstream and a weak shortwave trough
approaches the area. CAMS continue to struggle mightily with under
initializing the ongoing convection and killing it off too
quickly. However, given the highly moist and unstable environment
in place with sufficient forcing from the shortwave, dryline, and
composite outflow the threat of focused flash flooding should
persist for at least several more hours.

Asherman

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

ATTN...WFO...FWD...SJT...

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

LAT...LON   32059724 31599637 31179627 30959725 31179881
            31469933 31979909