SPC AC 141938
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0238 PM CDT Sun Aug 14 2022
Valid 142000Z - 151200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS
AFTERNOON/EVENING ACROSS CENTRAL HIGH PLAINS...NORTHWEST ND...AND
EASTERN KY VICINITY...
Scattered convection capable of isolated/marginally severe hail and
wind will spread across portions of the central High Plains,
northwest North Dakota, and eastern Kentucky and vicinity this
afternoon and evening.
Previous forecast remains on track with no changes needed to the
preceding outlook. See discussion below for more details.
.PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 14 2022/
...Central High Plains this afternoon/evening...
Embedded perturbations will move eastward toward the central High
Plains, around the north-northwest periphery of the persistent
midlevel high over the central/southern Plains. Low-level upslope
flow will help maintain boundary-layer dewpoints in the mid 50s to
lower 60s as low-level lapse rates steepen with afternoon
heating/mixing. Midlevel lapse rates will not be particularly steep
within the monsoonal moisture plume, but steepening low-level lapse
rates and modest deep-layer shear will support the potential for a
few storm clusters capable of producing strong/isolated severe
outflow winds this afternoon/evening.
...Northwest ND late this afternoon/evening...
A diffuse surface cyclone/lee trough will persist through the
afternoon near the MT/ND border, near the southern edge of the main
belt of mid-upper westerlies over the southern Prairie Provinces.
Boundary-layer dewpoints in the mid 60s across western ND, near the
east edge of the deeper mixing across MT, will support moderate
buoyancy (MLCAPE of 1500-2000 J/kg) and the potential for isolated
thunderstorm development near the international border by late
afternoon. Assuming a storm or two forms and moves southeastward
into ND, the environment will conditionally favor some potential for
supercells/small clusters capable of producing isolated large hail
and damaging winds for a few hours late this afternoon through late
...Southern IN to eastern KY/western VA this afternoon/evening...
A weak surface cyclone will move southeastward from IN toward
eastern KY, in advance of an embedded speed max digging
southeastward over IL/IN. Though clouds will slow surface heating
some and midlevel lapse rates will not be particularly steep,
boundary-layer dewpoints well into the 60s and surface heating in
cloud breaks will support MLCAPE of 500-1000 J/kg. Deep-layer
northwesterly shear of 35-40 kt will be sufficient for
organized/supercell storms capable of producing marginally severe
hail and isolated wind damage.
...South TX this afternoon...
A tropical low is moving inland over south TX as of late morning,
with some banded convective structures to the east of the center.
Since the low is already inland and is not expected to intensify,
wind profiles/vertical shear are likewise not expected to
strengthen. A weakly rotating storm or two may occur near the lower
TX coast as the convective bands spread westward/inland, but the
threat for tornadoes is too marginal to warrant the addition of an
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