ACUS03 KWNS 171924
SWODY3
SPC AC 171924
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0224 PM CDT Sat May 17 2025
Valid 191200Z - 201200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE CENTRAL PLAINS INTO MISSOURI...
...SUMMARY...
Severe storms with all severe weather hazards remain likely from
portions of the Midwest to the southern Plains on Monday.
...Synopsis...
The embedded mid-level impulse (responsible for Day 2 severe) will
approach the Great Lakes region as the primary upper trough ejects
into the Plains states on Monday. Some surface low strengthening is
expected along or just north of the KS/OK border by afternoon,
supporting a sharpening dryline along the I-35 corridor, with a warm
front draped from eastern NE to the OH River. Scattered to
potentially widespread thunderstorm development is likely by mid
afternoon along the warm front and ahead of the dryline. With strong
vertical wind shear and instability in place over the Plains to the
Midwest, severe storms with all convective hazards are likely.
Strong thunderstorms may also develop further east along the warm
front over the TN Valley as well.
...Portions of the central Plains into the Midwest...
Scattered showers and thunderstorms may be ongoing at the start of
the period (12Z Monday morning). However, gradual clearing of this precipitation and associated cloud cover should support
destabilization along and south of a warm front during the
afternoon. Boundary layer heating, along with increasing deep-layer
ascent from the approaching upper trough, will encourage the
development of several thunderstorms along the warm front during the
afternoon, from far eastern NE to the MO/IL border. On the warm side
of the front, 70+ F surface dewpoints beneath steep mid-level lapse
rates will boost MLCAPE to over 3000 J/kg amid 50 kts of effective
bulk shear. NAM forecast soundings depict enlarged hodographs as
well. Supercells may develop along the warm front, accompanied by
large hail. Storms that can remain surface based, along or just
south of the warm front, will have the best chance to produce
tornadoes.
...Portions of the central into southern Plains...
Modest to considerable cloud cover, perhaps accompanied by showers,
may overspread parts of the central and southern Plains Monday
morning. Nonetheless, enough clearing should take place ahead of a
sharpening dryline by afternoon to support considerable
destabilization given steep mid-level lapse rates from an EML. The
dryline should be positioned just west of I-35 by mid-afternoon,
with surface dewpoints ahead of the dryline exceeding upper 60s to
70 F, supporting well over 3000 J/kg MLCAPE on a widespread basis.
Strong southwesterly mid-level flow overspreading southeasterly
surface flow ahead of the low will result in over 50 kts of
effective bulk shear. By mid afternoon, at least scattered supercell development is expected all along the dryline, from southeast NE to
central OK, with more isolated supercell coverage likely over
northern into central TX. Given ample buoyancy and deep-layer shear,
large hail is expected, with very large hail over 2 inches in
diameter likely with the more dominant supercell structures. By late
afternoon into early evening, the strengthening of the low-level jet
over central and eastern KS/OK will support substantial low-level
veering of the vertical wind profile, with notable low-level
hodograph size/curvature in forecast soundings. As such, the more
dominant, right-moving supercells will have the potential to produce
tornadoes, and at least a few strong tornadoes are possible.
...Portions of the TN Valley...
Multiple rounds of thunderstorms are possible along a residual
baroclinic boundary across the TN Valley, both during the morning
hours, and later in the evening. While not quite as unstable as
points farther to the west, modest mid-level lapse rates amid
elongated hodographs should support multicells, supercells, and
short line segments. The stronger storms may be capable of isolated
instances of large hail, gusty winds, and perhaps a brief tornado.
..Squitieri.. 05/17/2025
$$
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