SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0259 PM CDT Sat Apr 06 2024
Valid 062000Z - 071200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL PLAINS...
...SUMMARY...
Severe storms remain possible across parts of the central into
southern Plains this afternoon and early evening. Scattered severe
wind gusts and isolated large hail are the primary risks with the
stronger storms, but a couple of tornadoes may also occur.
...20Z Update...
A band of low-topped convection currently arcs from the NE Panhandle
southeastward towards south-central NE and north-central KS. This
activity is occurring along/near a warm front, but with limited
low-level moisture. Strong low/mid-level flow associated with a deep
cyclone over the central High Plains should support continued
convective organization, with the primary threat remaining severe
wind gusts up to 75 mph. See Mesoscale Discussion 377 for more
details on the near-term severe threat across this area.
Additional thunderstorm development appears likely this afternoon
southward along an eastward-mixing dryline from parts of
north-central to south-central KS, and eventually central OK. Some
severe wind/hail risk will exist with any robust convection that can
be sustained, although shallow low-level moisture continues to be a
potentially limiting factor. Still, the better large-scale
ascent/forcing, and greater thunderstorm coverage, should remain
focused across KS where the Slight Risk is delineated.
Finally, a small westward expansion has been made to the Marginal
Risk across central OK. Latest visible satellite and radar trends
show attempts at convection occurring along the dryline across
north-central OK. Isolated thunderstorms should eventually develop
while posing a risk for marginally severe hail and strong to severe
wind gusts. See Mesoscale Discussion 378 for additional information
on the severe potential across OK this afternoon.
..Gleason.. 04/06/2024
.PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Apr 06 2024/
...Central/Southern Plains...
An increasingly negative-tilt mid/upper-level trough will overspread
the High Plains, with the upper jet exit region influencing the
central Plains as surface cyclogenesis occurs across northeast
Colorado/northwest Kansas into Nebraska through this evening. To the
south of the surface cyclone, a Pacific cold front will gradually
overtake a preceding dryline across the south-central Plains into
this evening. Modest early season low-level moisture (evident in
regional 12z soundings such as Norman/OUN, Fort Worth/FWD, Dodge
City/DDC, and North Platte/LBF) is expected to somewhat limit the
overall magnitude of today's severe risk, with a spatially narrow
corridor of warm-sector dewpoints generally limited to the 40s F
across Nebraska, some low/mid 50s F across Kansas, upper 50s F
across Oklahoma, and low 60s F relegated to north/central Texas, as
strong northward moist advection somewhat compensates for ample
diurnal mixing.
Even with low-level moisture/buoyancy limitations, very strong
large-scale ascent attendant to the ejecting upper-level trough will
aid in initial storm development early this afternoon near the
surface low/triple point vicinity across far northeast Colorado, far
northwest Kansas into western/central Nebraska, as well as other
parts of northern/central Kansas by mid/late afternoon. A few
low-topped supercells may occur before a transition to more linear
modes this evening.
Storms that can acquire supercell characteristics would yield the
greatest threat for isolated large hail (1.0-1.5 inch diameter).
While the tornado threat may tend to be limited by sparse low-level
moisture, sufficient low-level shear/SRH could support at least a
brief tornado threat with any stronger sustained supercell and/or
within a transitioning linear mode, especially in closer proximity
to the surface low over west-central/southern Nebraska and far
northern Kansas. It appears the predominant risk will be severe
gusts in the 60-80 mph range owing to steep 0-2 km lapse rates, very
strong boundary-layer flow, and a more linear mode over time.
While the primary severe risk is expected across parts of Nebraska
and northern Kansas, isolated severe potential will also exist in
vicinity of the dryline/Pacific front as it extends southward from
southern Kansas into central Oklahoma around peak heating. While
boundary layer moisture will be modest, isolated/widely scattered
thunderstorm development is expected toward/after sunset as far
south as I-40 in Oklahoma, and possibly as far south as the Red
River vicinity. That said, some forecast soundings (especially 12z
NAM but also HRRR) reflect some lingering mid-level
inhibition/subsidence that does not fully resolve early this
evening, especially with southward extent, which likely has
implications for the isolated nature of the development as well as a
less-than-typical early April potential for large hail. A few storms
could even develop late tonight in vicinity of the Pacific front
across central Texas toward the Hill Country.
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