Subj : MESO: Mesoscale Discussion 0858
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sun May 18 2025 18:59:15

ACUS11 KWNS 181859
SWOMCD
SPC MCD 181858=20
TXZ000-OKZ000-182130-

Mesoscale Discussion 0858
NWS Storm Prediction Center Norman OK
0158 PM CDT Sun May 18 2025

Areas affected...Northwest to west-central Texas

Concerning...Severe potential...Watch likely=20

Valid 181858Z - 182130Z

Probability of Watch Issuance...80 percent

SUMMARY...Thunderstorm development along the dryline is expected
roughly between 20-22 UTC across northwest to west-central Texas.
The convective environment will support supercells capable of large
hail, severe gusts, and a few tornadoes. Watch issuance is likely as
storms begin to develop.

DISCUSSION...Recent GOES visible imagery shows shallow, but slowly
deepening, cumulus along and just ahead of a sharpening dryline as
it continues to mix east and boundary-layer depth increases amid
filtered diurnal heating. Latest RAP/HRRR forecast soundings suggest
any lingering MLCIN will be minimized as surface temperatures warm
into the 92-95 F range over the next few hours within the warm
sector. Regional VWPs show flow within the lowest 2-3 km AGL
oriented roughly along the dryline, which should promote adequate
residence times for parcels to reach their LFCs and initiate deep
convection. Latest high-res solutions suggest this should occur
generally between 20-22 UTC. Thunderstorms will mature within a very
unstable air mass with MLCAPE values exceeding 4000 J/kg and
effective shear on the order of 40-50 knots. Limited directional
shear will initially promote splitting supercells with an attendant
very large hail threat (most probable max hail size may be 2-3
inches in diameter). Southeasterly low-level winds across northwest
TX may support adequate low-level veering for some tornado threat.
Further south (roughly south of I-20), 1.5 to 2.5 km LCL heights and
more backed low-level flow will modulate the initial tornado
potential. After 00 UTC a strengthening low-level jet will increase
low-level hodograph curvature and support an increasing tornado
threat with any remaining discrete right-moving supercells across
much of central/northern TX. Watch issuance will likely be needed as
thunderstorm initiation becomes more imminent.

...Moore/Hart.. 05/18/2025

....Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj=
g!5zsBoE66gKx-A5aXNRdYK71Hv6n9fYs9RNOshyWr-nhhSll8g70AVvNe3qgx3tjR1rjoFRhuv=
mn0ImOd7IrBYSlK7Gc$  for graphic product...

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

LAT...LON   30980132 31340102 32480013 32860000 33250004 33760012
            34079996 34279965 34239910 34149872 33989849 33609835
            33029840 32379865 31779894 31059956 30879979 30480066
            30370100 30450133 30660147 30980132=20

MOST PROBABLE PEAK TORNADO INTENSITY...100-130 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN


=3D =3D =3D
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