ACUS01 KWNS 180542
SWODY1
SPC AC 180540

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1240 AM CDT Sun May 18 2025

Valid 181200Z - 191200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF KANSAS AND OKLAHOMA...

...SUMMARY...
Severe thunderstorms capable of all severe hazards are expected
later today across portions of the central and southern Plains. The
potential for a few strong tornadoes exists across parts of Kansas
and Oklahoma.

...Central/Southern Plains...

Strong upper trough is digging southeast across the Great Basin
early this morning. This feature is forecast to advance into the
Four Corners region by 18z as 500mb speed max translates across AZ
into NM. By early evening, strongest mid-level flow is forecast to
extend across northeast NM into western KS. This evolution will
suppress the height field across the central High Plains such that
large-scale forcing will likely influence the dry line as far south
as I-40 near the TX/OK border.

While several 00z models struggle to develop convection along the
dry line, strong boundary-layer heating is expected across the
southern High Plains. Zero-3km lapse rates will approach dry
adiabatic by late afternoon as surface temperatures soar through the
mid 90s across the eastern TX Panhandle into the TX South Plains. As
a result, deep thermals are expected and isolated thunderstorms
should develop as CINH will prove minimal.

Scattered convection is currently noted across northeast OK into
southeast KS/southwest MO. This activity will likely persist into
the early parts of the day1 period. Strongest low-level moisture
surge should be across western OK into extreme southwest KS as LLJ
will focus across this portion of the Plains early in the period.
While early-day convection may generate locally severe hail/wind,
the primary concern for severe will be with late-day convection.
Current thinking is strong heating along the dry line will prove
instrumental in thunderstorm development as convective temperatures
are breached, sometime after 22z. Primary corridor for initiation
should be across southwest KS into northwest OK. This activity will
be strongly sheared and supercells should mature quickly as they
move northeast toward/across the warm front draped downstream across
KS. Very large hail and tornadoes are certainly a concern with
surface-based convection, while hail is the primary concern with
elevated convection north of the warm front.

It's not entirely clear how much convection will develop along the
dry line south of I40, especially across TX. However, minimal
inhibition warrants concern, as any updrafts that evolve within a
strongly sheared and buoyant air mass should produce at least large hail.

Farther north, left-exit region of mid-level jet will encourage a
secondary corridor of strong/severe thunderstorms from northeast CO
into western NE. Surface low is expected to track across eastern CO
into western KS which will maintain a moist/upslope component to
boundary layer across this portion of the High Plains. Strong
low-level warm advection will assist organized convection as it
spreads northeast during the overnight hours.

..Darrow/Halbert.. 05/18/2025

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