RSS Mesoscale Discussions from Storm Prediction Center
SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0258 PM CDT Fri Apr 26 2024
Valid 262000Z - 271200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL PLAINS/MID MISSOURI VALLEY INTO THE OZARKS AND NORTHEAST
TEXAS...
...SUMMARY...
Tornadoes, including a couple of strong tornadoes, very large hail
(some greater than 2 inches in diameter), and wind damage remain
possible this afternoon/evening from eastern Kansas/Nebraska into
Iowa, western Missouri, eastern Oklahoma, western Arkansas, and
northeast Texas.
...20Z Update...
Adjustments have been made to the Enhanced and Slight Risks across
central/eastern NE into eastern KS/OK to account for latest
observational trends and short-term model guidance. Convection has
recently developed along the dryline across southeast KS, with
additional development possible across north-central into
east-central KS over the next couple of hours. Any supercells that
can persist across this region will pose a threat for very large
hail given steep mid-level lapse rates, strong deep-layer shear, and
sufficient instability. A threat for tornadoes, some strong, will
also exist for these areas with ample low-level shear present per
recent VWPs from KTWX/KEAX. For more details on the near-term severe
threat across this area, see Mesoscale Discussion 531.
A threat for strong tornadoes and large to very large hail continues
across parts of NE with ongoing supercells along/near a warm front.
Multiple supercells have produced tornadoes already, and strong
low-level shear will favor updraft rotation and strong tornado
potential with this activity through the evening as it spreads into
eastern NE and eventually western IA and vicinity. Reference
Mesoscale Discussion 530 for additional information.
Behind the dryline in north-central TX, elevated thunderstorms may
develop late tonight into early Saturday morning. A Marginal Risk
for hail has been maintained across parts of northwest TX to account
for this isolated severe potential.
..Gleason.. 04/26/2024
.PREV DISCUSSION... /ISSUED 1142 AM CDT Fri Apr 26 2024/
...NE/IA/MO/KS...
Water vapor loop shows a strong shortwave trough rotating across
KS/NE. A deep surface low is analyzed ahead of this trough over
central NE, with a dryline extending southward into central KS. A
corridor of ample low-level moisture is present ahead of the dryline
over southeast NE/northeast KS, where daytime heating will lead to
moderate MLCAPE values and rapid thunderstorm development by
mid-afternoon. Backed low-level winds and favorable shear profiles
will promote supercells in the bent-back region of the low, with
very large hail and tornadoes possible. These storms will progress
eastward into western IA and northwest MO through the early evening.
A strong tornado or two is possible in this region.
...OK/MO/AR...
A large nocturnal MCS that affected much of OK has quickly weakened
and departed, with rapid northward return of low-level moisture
occurring in the wake of the system. By mid-afternoon, mid-upper
60s dewpoints are expected along the dryline over east-central OK.
Forecast soundings show very steep mid-level lapse rates and
favorable shear profiles to promote discrete supercells capable of
all severe hazards, including very large hail and strong tornadoes.
Storms will track northeastward into southwest MO and northwest AR
this evening. CAM guidance varies on coverage of storms, but
parameters appear quite strong and warrant an upgrade to ENH given
the conditional risk of significant severe weather.
...Northeast TX...
A third area of significant risk of severe storms lies across parts
of northeast and east-central TX today. A cluster of
severe/supercell storms has formed this morning to the west of Waco,
TX. These storms are expected to increase in coverage through the
afternoon and develop eastward across much of northeast TX.
Forecast soundings show a very moist and unstable environment, with
sufficient low-level and deep-layer shear for persistent supercell
structures and risks of a few tornadoes and very large hail. Given
the number of storms and the favorable environment, have also
upgraded this narrow corridor to ENH.
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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1230 PM CDT Fri Apr 26 2024
Valid 271200Z - 281200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN/CENTRAL PLAINS...
...SUMMARY...
Numerous severe thunderstorms are likely Saturday into Saturday
night. The greatest severe threat is currently anticipated across
parts of the central and southern Plains, where very large hail,
damaging winds, and multiple strong tornadoes will be possible. A
broader area of potential threat will extend from south-central
Texas north-northeastward to the Great Lakes.
...Synopsis...
A shortwave trough over the Upper Midwest Saturday morning should
further de-amplify as it moves across the Great Lakes through the
day in tandem with a weakening surface low. A large-scale upper
trough over the Southwest will eject across the southern/central
Plains through the period, while an attendant 50-70 kt southwesterly
mid-level jet overspreads these same regions. At the surface, lee
cyclogenesis is expected to occur over western KS through Saturday
afternoon, before the low eventually develops towards central KS
Saturday night. A dryline will extend southward from this low across
the southern/central High Plains, and a warm front will extend
northeastward from the low across the central Plains into the Upper
Midwest.
...Southern/Central Plains...
Most guidance develops thunderstorms early Saturday morning across
northwest TX into central OK. This activity will likely be related
to a subtle mid-level shortwave trough ejecting northeastward across
the southern High Plains, along with ascent along a westward
retreating dryline and warm/moist advection attendant to a southerly
low-level jet. Steep lapse rates aloft fostering moderate to strong
MUCAPE, along with sufficient deep-layer shear, should support some
large hail threat with this early day convection. The potential for
these morning thunderstorms to continue into the afternoon across
central/eastern OK and eastern KS remains uncertain. Even so, some
severe threat may persist with this activity as it spreads eastward.
Fairly meridional flow at low/mid levels suggests a messy mode may
develop, with numerous thunderstorm mergers/interactions possible.
In the wake of this activity, it still appears likely that
substantial destabilization will occur along/east of the dryline and
south of the warm front, with daytime heating of a moist low-level
airmass supporting MLCAPE of 2000-3500 J/kg from north-central KS
southward into parts of western OK and northwest TX. As ascent with
the ejecting upper trough overspreads this warm sector, multiple
attempts at supercell development will likely occur both along the
dryline and warm front, as 40-50 kt of deep-layer shear promotes
robust thunderstorm organization. Any supercells that can form and
persist will be capable of producing very large hail in excess of 2
inches in diameter. With time Saturday evening, a steadily
strengthening low-level jet will foster increased low-level shear,
and greater tornado potential. Multiple strong tornadoes appear
possible during the late afternoon to early evening time frame, as
effective SRH of 150-250+ m2/s2 supports low-level updraft rotation.
Locally greater low-level shear will probably be realized along/near
the warm front Saturday evening, and the Enhanced Risk has been
expanded slightly northward to include more of
south-central/southeast NE. It remains unclear how long a discrete
mode will be able to be maintained, as a tendency for convection to
grow upscale into one or more bowing clusters appears likely
Saturday evening/night. As this mode transition occurs and
convection spreads eastward, a greater threat for severe/damaging
winds will probably be realized across the southern/central Plains.
Due to the influence of the morning convection and potential for
messy storm modes/convective evolution Saturday afternoon,
confidence was not high enough to include greater tornado and/or
hail probabilities across the southern/central Plains at this time.
...Northwest Kansas into Southwest Nebraska and Northeast
Colorado...
Low-level easterly flow will maintain modest low-level moisture
within the post-frontal regime from northwest KS/southwest NE into
northeast CO. Steep midlevel lapse rates will support MLCAPE
increasing to around 500 J/kg, with veering wind profiles with
height through mid levels supporting some potential for organized
convection. A supercell or two could evolve within this regime, with
an attendant threat of large hail and possibly a tornado.
...Upper Midwest/Great Lakes...
A mostly separate regime of at least isolated severe thunderstorm
potential remains evident along/ahead of the front from eastern IA
into parts of the Great Lakes region. While the influence of the
weakening shortwave trough initially over the Upper Great Lakes may
remain mostly displaced to the north of the warm sector, diurnal
heating/destabilization and gradually lessening convective
inhibition may support isolated storm development by late afternoon
along the front. Deep-layer shear will remain sufficient for updraft
organization, supporting a potential for supercells and/or stronger
clusters capable of producing severe hail, damaging gusts, and
possibly a tornado or two. Some increase in storm coverage will be
possible into the evening as the cold front moves southeastward.
Thunderstorms should weaken overnight across this region, though a
stronger cluster to two could move from eastern portions of the
central Plains toward the upper MS Valley before the end of the
forecast period.
..Gleason.. 04/26/2024
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