613
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

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

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