SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0243 PM CDT Mon Apr 11 2022
Valid 112000Z - 121200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS EASTERN
OKLAHOMA INTO ARKANSAS...
...SUMMARY...
Isolated to scattered severe thunderstorms are expected later this
afternoon into early tonight from parts of northeast Texas to the
Ozarks and Mid-South, with the greatest threat expected over parts
of far eastern Oklahoma and Arkansas. Very large hail, damaging
winds, and a strong tornado or two all appear possible.
...Eastern Oklahoma/Arkansas...
Latest GOES-16 imagery shows signs of decreasing inhibition across
northeast TX into eastern OK. Deepening congestus, increasing echo
tops, and a few lightning strikes are noted across eastern OK along
the stationary boundary, possibly indicating the early signs of
sustained, surface-based convective initiation. These trends are
expected to continue through the late afternoon as inhibition
continues to wane and instability increases to near 2500 J/kg MLCAPE
amid increasing cloud breaks. This is in line with latest guidance,
which shows thunderstorms increasing in coverage after 21 UTC across
eastern OK into central AR (see MCD 447 for additional details).
Small changes are made to the Enhanced risk area to better capture
the northward extent of the developing thunderstorms along the
stationary boundary, but the overall forecast remains on track.
..Moore/Mosier.. 04/11/2022
.PREV DISCUSSION... /ISSUED 1120 AM CDT Mon Apr 11 2022/
...AR to southeast OK/north TX this afternoon into early tonight...
Broadly cyclonic flow aloft will persist over the Plains and western
CONUS, as a lead shortwave trough ejects east-northeastward over
Lake Superior, and an upstream trough will amplify toward the Great
Basin. An outflow boundary across AR and a surface front across
east central and southeast OK have stalled and these boundaries will
provide a focus for additional thunderstorm development later this
afternoon into this evening, as a subtle mid-upper speed max
progresses east-northeastward from the TX Panhandle. Late in the
period, the front will begin to move northward as a warm front
across OK, in response to strong lee cyclogenesis across the central
High Plains (downstream from the Great Basin midlevel trough).
Boundary-layer dewpoints in the mid-upper 60s continue to spread
northward across TX/LA toward southeast OK and AR, to the south of
the front and the outflow boundary across northern AR. Clouds will
tend to slow surface heating in AR where the moist layer is
relatively deep, but convective inhibition is not as strong compared
to areas farther southwest in TX, based on the very warm elevated
mixed layer noted in regional 12z soundings with convective
temperatures at or above 90 F. However, surface heating will be
stronger from southeast OK into northeast and north central TX where
cloud breaks will be more pervasive. Though forcing for ascent and
the prospects for surface-based storm development are uncertain
across north TX along the front and dryline, storm development is
more probable by mid-late afternoon along the front/outflow along
the northeast edge of the stronger surface heating/deeper mixing in
southeast OK. Any storms that form along or just south of the
front/outflow from southeast OK into AR will likely become
supercells, given MLCAPE of 2000-3000 J/kg and effective bulk shear
near 50 kt.
The large buoyancy, northeast extent of the midlevel lapse rates
near or above 8 C/km, and supercell wind profiles will support the
threat for isolated very large hail (potentially near the size of
baseballs). Low-level moisture and hodograph length/clockwise
curvature suggest that tornadoes will be possible with any
persistent supercells, including a strong tornado or two.
Otherwise, storms may persist into the early overnight hours and
evolve into a cluster or two while spreading eastward across AR,
before weakening late tonight as the subtle midlevel trough passes
and background height rises commence over AR.
Read more CHECK UPDATE ZOOM GRAPHIC
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