ACUS11 KWNS 181640
SWOMCD
SPC MCD 181640=20
ARZ000-MOZ000-OKZ000-181845-

Mesoscale Discussion 0857
NWS Storm Prediction Center Norman OK
1140 AM CDT Sun May 18 2025

Areas affected...Northeast Oklahoma into northwest Arkansas and far
southwest Missouri

Concerning...Severe potential...Watch possible=20

Valid 181640Z - 181845Z

Probability of Watch Issuance...40 percent

SUMMARY...Elevated thunderstorms developing across northeast
Oklahoma into northwest Arkansas and southwest Missouri may pose a
hail threat through early afternoon. Confidence in the coverage and
duration of this threat is uncertain, but convective trends will be
monitored.

DISCUSSION...Isentropic ascent over a residual convective outflow
across northeast OK/northwest AR has promoted scattered
thunderstorms within the past hour. Based on forecast soundings and
surface observations, this convection is likely being driven by
ascent within the 850-700 mb level on the eastern fringe of an EML.
Steep lapse rates above this layer (around 8 C/km) is supporting
MUCAPE values between 1500-2000 J/kg, and strong flow within the
850-250 mb layer is supportive effective shear values around 50
knots. Consequently, organized convection is possible and may pose a
severe hail threat through the next few hours. Weak ascent along the
outflow boundary may be insufficient for sustained deep convection
despite the favorable convective environment, and stable conditions
in place downstream across northern AR/southern MO should limit the
spatial extent of the threat. As such, overall coverage, duration,
and intensity is uncertain. However, if convection can persist
through mid afternoon, additional heating may support a higher
potential for sustained/intense storms. Watch issuance is currently
not likely, but convective trends will continue to be monitored
given the environment.

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

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!6ZhZPoBcUK4WNlkKpUhVrzSAj498QpMqYfJteRqcfacr4CeaaQJaN4RdJmWMvaGCclWsGZAAr= 2bYODSOyRsjcHmI5AU$ for graphic product...

ATTN...WFO...LZK...SGF...TSA...

LAT...LON 35089407 35239499 35779567 35999572 36219568 36719447
36709389 36459356 36179327 35929306 35639287 35389299
35269311 35139351 35089407=20

MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN


=3D =3D =3D
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