898
ACUS01 KWNS 032000
SWODY1
SPC AC 031958

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0258 PM CDT Mon Jun 03 2024

Valid 032000Z - 041200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE SOUTHERN
GREAT PLAINS INTO THE ARKLATEX AND ACROSS PARTS OF WI/IL/IA...

...SUMMARY...
Strong to severe thunderstorms are possible over parts of the
Mississippi Valley into the Ozark Plateau and southern Plains
through evening.  A more concentrated area of severe thunderstorm
risk may become focused across southwest and southern Oklahoma and
adjacent portions of Texas this evening into early tonight.

...Synopsis...

No changes have been made to severe probabilities with the 20z
outlook update. See MCDs 1150, 1151, and Severe Thunderstorm Watch
385, for short term severe storm info across the ArkLaTex and WI/IL.

Elsewhere, cumulus is deepening across the eastern TX Panhandle into
southwest OK/western north TX in the vicinity of an outflow
boundary. Strong heating into the upper 80s/low 90s F and dewpoints
recovering into the low 70s F is resulting in an axis of strong to
extreme instability. Backed low-level flow near the boundary is
enhancing low-level shear, and the KFDR VWP is showing large
low-level hodographs and 0-1 km SRH near 200 m2/s2. While
large-scale ascent is weak, low-level convergence and strong
instability should be sufficient for a storm or two. While expected
limited storm coverage precludes higher probabilities, significant
severe and a strong tornado will be possible.

..Leitman.. 06/03/2024

.PREV DISCUSSION... /ISSUED 1128 AM CDT Mon Jun 03 2024/

...Southern Plains to the lower MS Valley through tonight...
IR/radar imagery late this morning shows an MCS over central/eastern
OK.  This thunderstorm complex is forecast to continue moving
east-southeast into western AR and potentially the Ark-La-Miss
region by early evening.  Latest thinking is this thunderstorm
activity will serve as a northern bound for Slight-Risk equivalent
wind probabilities due in part to 1) residual cold pool and
associated cloud debris from AR-related storms, 2) weak instability
noted on the 12z Little Rock, AR raob.  It is not clear whether
severe potential rejuvenates with this MCS or if it is primarily
attendant to additional storm development downstream.  Regardless,
it seems some threat for damaging gusts will develop into the
afternoon/evening.

Outflow trailing southwestward from these morning storms will likely
provide a mesoscale focus for supercell development this afternoon
along the stalling boundary in the vicinity of southwest OK border.
Here, rich low-level moisture (boundary-layer dewpoints in the
low-mid 70s) and surface heating will drive MLCAPE to near 5000-6000
J/kg with weakening convective inhibition after peak surface
heating.  At least isolated thunderstorm development is expected
late this afternoon/evening near the outflow/dryline intersection
(close to the southwest OK/southeast TX Panhandle border), and
storms will subsequently move southeastward along the stalled
boundary.  Substantial veering from low-level east-southeasterlies
to 20-30 kt mid-level flow will yield sufficient effective shear
(30-40 kt) for supercells.  Model-based hodographs enlarge
considerably during the 23-01z period, and coupled with the extreme
buoyancy, will favor the potential for a couple of tornadoes
(perhaps one tornado being strong).  Very large hail (up to 3 inches
in diameter) and severe gusts will also be accompanying hazards with
these storms.  A continuation of the evening storm activity or
additional storms associated with warm advection, will be possible
tonight across southern and central OK yielding a severe risk.

...Southern WI and vicinity this afternoon/evening...
No change in forecast thinking from the previously issued forecast.
A remnant MCV over IA will move northeastward over WI this
afternoon, atop a subtle surface front/trough and differential
heating zone.  As heating continues through early afternoon,
temperatures will warm to 75-80 F in cloud breaks and boundary-layer
dewpoints increase to 65-70 F.  This low-level destabilization will
yield moderate buoyancy (MLCAPE near 1500 J/kg) developing in the
warm sector from eastern IA/northwest IL into southern WI.  Despite
some localized enhancement to vertical shear with the remnant MCV,
deep-layer vertical shear will generally remain weak (primarily
supporting multicell clusters and low-end supercell structures).
Thus, expect a few clusters of storms capable of producing
occasional wind damage and isolated large hail of 1-1.5 inches in
diameter for a few hours this afternoon/evening.

...Northeast MT/ND...
A potent mid- to upper-level shortwave trough initially over the
Pacific Northwest this morning will quickly move east into central
MT by early evening.  Models indicate perhaps isolated storms
developing across western ND late this afternoon and widely
scattered storms developing farther west into north-central MT
spreading east.  Forecast sounding profiles indicate weak
instability but perhaps an isolated threat for severe gusts may
develop with the storms.  This activity will likely persist through
the late evening as it moves east.

$$