LIVE MAP (ABOVE) ... SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Thu May 11 2023
Valid 121200Z - 131200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
MID-MISSOURI VALLEY AREA AND VICINITY...AND FROM OKLAHOMA SOUTHWARD
TO THE RIO GRANDE...
...SUMMARY...
Strong/severe storms are expected to begin during the afternoon,
across a broad area extending from the Mid-Missouri Valley southward
to the Rio Grande Valley. Very large hail and damaging wind gusts
will likely be the primary severe threats over the southern half of
the area into the overnight hours, while damaging winds and hail,
and a couple of tornadoes, will be possible across the Mid Missouri
Valley area through the evening.
...Synopsis...
Weak upper troughing will prevail across much of the Intermountain
Region and into the Plains states on Friday. Within the broad area
of cyclonic flow, a weakening low is forecast to drift slowly
northeastward across western Nebraska, while a second cyclonic
disturbance is forecast to shift northeastward across northern
Mexico, and into western Texas through the second half of the
period. Elsewhere, northwesterly flow aloft will persist across the
Northeast, with ridging across the Southeast and Midwest and also
across the West Coast states.
At the surface, a weak low will drift across western Nebraska
beneath the upper system, while an arcing, very slow-moving cold
front stretches from eastern Nebraska into central Kansas and
western Oklahoma, and into the Texas South Plains during the
afternoon and evening.
...Mid-Missouri Valley area and vicinity...
A cluster of thunderstorms may be ongoing at the start of the period
across portions of western Nebraska near the weakening upper low.
Moderate to strong afternoon destabilization across the Mid Missouri
Valley vicinity will allow additional storm development -- in an
arcing manner extending eastward/southeastward across Nebraska, and
southward across eastern Kansas, with coverage diminishing with
southward extent.
With flow aloft sufficient for organized storms across this area,
the greatest supercell potential is evident at this time from
northeastern Nebraska southeastward toward northeastern Kansas
during the late afternoon, and then spreading east-northeastward
into western Iowa and vicinity during the evening. Along with risk
for locally damaging winds and hail with stronger storms, a couple
of tornadoes will be possible given backed/southeasterly low-level
flow contributing to ample low-level shear. Risk should gradually
diminish into the overnight hours.
...Oklahoma to the Rio Grande...
Thunderstorm development is expected to occur from the central
Oklahoma vicinity southwestward to the Texas South Plains, along a
weak surface baroclinic zone, as daytime heating of a moist
pre-frontal boundary layer yields 3000 to 4000 J/kg mixed-layer CAPE
by late afternoon. While only modest shear is forecast to be
present, mid-level southwesterlies around 25 kts atop low-level
southeasterlies should result in sufficient shear for rotating
updrafts -- and attendant risk for very large hail and locally
damaging wind gusts.
As the weak upper low approaches the Rio Grande during the
afternoon, storms will also increase from the Transpecos region into
the Edwards Plateau area with time. Along wind the favorably strong
CAPE, increasing flow associated with the approaching upper
disturbance will support organized/rotating storms -- which appear
likely to grow upscale into a large MCS through the evening as a
low-level jet increases nocturnally. Very large hail should be the
primary threat initially, but damaging wind potential will likely
increase into the evening, and into the overnight hours as storms
expand/progress east/southeast with time.
..Goss.. 05/11/2023
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