283
ACUS02 KWNS 051739
SWODY2
SPC AC 051737

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1237 PM CDT Sun May 05 2024

Valid 061200Z - 071200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS
WEST-CENTRAL/CENTRAL OKLAHOMA AND SOUTH-CENTRAL KANSAS...

...SUMMARY...
Numerous severe thunderstorms are expected to develop and move
eastward Monday afternoon through Monday night across parts of the
southern/central Plains. Multiple strong/potentially long-track
tornadoes, very large to giant hail, and severe/damaging winds all
appear likely.

...Synopsis...
Upper cyclone apparent in Sunday morning satellite imagery over
northern/central CA and the western Great Basin is expected to
devolve into an open wave as it progresses eastward. This wave is
forecast to continue eastward through the central Rockies and into
the central Plains on Monday, becoming increasingly negatively
tilted as it does. Strong mid-level flow will accompany this system,
spreading eastward/northeastward into the central Plains early
Monday and into the southern High Plains by Monday afternoon.
Additional maturing into a closed mid-latitude cyclone is possible
across the northern High Plains late Monday evening/early Tuesday
morning.

Progression of this shortwave trough will contribute to significant
mass response across the Plains, with strong low-level moisture
advection resulting in mid 60s dewpoints to the OK/KS border by the
early afternoon. Low 60s dewpoints will likely reach into eastern NE
by the late afternoon. This increasing low-level moisture beneath
steep mid-level lapse rates/cold mid-level temperatures will result
in a moderate to strongly unstable airmass ahead of the approaching
shortwave across much of OK, KS, and NE. Numerous severe
thunderstorms are expected to develop as this wave interacts with
this airmass, beginning during the late morning/early afternoon
across SD/NE and then expanding southward across KS into OK
throughout the remainder of the afternoon into the evening.
Significant-severe weather is possible, including the potential for
giant hail from 3" to 4" in diameter, gusts around 80 mph, and
strong/potentially long-track tornadoes.

...Much of central/eastern NE and south-central/southeast SD into
western/northern/eastern KS and western MO...
Strong height falls associated with this system will likely begin
early Monday across NE and western/northern KS, interacting with the
moderately moist and buoyant air mass expected to be in place. The
cold front associated with this system will likely be moving through
western NE and KS during this period as well. This initial
development may not be overly strong, with the primary strengthening
likely delayed until the afternoon over central NE and north-central
KS where better low-level moisture and stronger buoyancy will be in
place. Given the boundary-parallel orientation of the deep-layer
shear vector and linear forcing along the front, relatively quick
upscale growth into an organized convective line appears likely.
This line would then track quickly eastward/southeastward through
the evening and overnight.

Large to very large hail around 2" to 2.5" in diameter is possible
with the initial more cellular development. Primary threat will
transition to severe gusts around 80 mph once the convective line
organizes and consolidates, which appears likely during the
afternoon. Additionally, despite the transition to a more linear
mode, the tornado threat is expected to increase with eastern
extent, supported by both an increase in low-level moisture/buoyancy
and strengthening low-level kinematic fields. The greater damaging
gust threat will likely extend into more far eastern KS and western
MO, and the higher wind probabilities were expanded eastward to
account for this potential. Some minor southeastward expansion of
the 10% tornado probabilities was made as well.

...Much of OK and adjacent portions of central/southern KS and far
northwest/north-central TX...
Height falls are expected to arrive later, and be more modest,
across OK and adjacent central/south KS than areas farther north.
Some capping appears likely through around 18Z as well. However,
continued low-level moisture advection coupled with daytime heating
is expected to result in air mass destabilization just as the height
falls/large-scale ascent move into the region. This scenario appears
to favor a discrete storm mode from south-central KS into southwest
OK. Overall coverage may be limited, particularly until 00Z, but any
storms that develop should quickly become supercellular and capable
of all severe hazards, including giant hail from 3" to 4" in
diameter, severe gusts to 80 mph, and strong tornadoes.
Additionally, forecast hodographs are quite long, with little
mid-level weakness. Mean storm motion is around 50 kt from 21 to
00Z, with Bunkers right motion around 30 kt. This should be more
than sufficient for storms to remain discrete and maintain supercell
characteristics. This also contributes to a greater potential for
long-track tornadoes. The tornado threat will persist pass sunset
and into the evening, supported by the persistence of ample
low-level moisture/buoyancy and a strengthening low-level jet. Most
current guidance maximizes the STP at 8-10 around 03Z over
south-central OK.

A threat for damaging winds and tornadoes should continue Monday
night into early Tuesday with eastward extent into eastern OK and
western AR given a sufficiently unstable and strongly sheared
environment.

..Mosier.. 05/05/2024

$$