RSS Mesoscale Discussions from Storm Prediction Center
SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0700 AM CDT Tue Apr 28 2026
Valid 281300Z - 291200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN PLAINS INTO THE LOWER MISSISSIPPI VALLEY AND
MID-SOUTH...
...SUMMARY...
Multiple rounds of severe thunderstorms will occur across parts of
the southern Plains into the lower Mississippi/Tennessee Valleys and
Southeast through this evening. Very large to giant hail (2-4+
inches), swaths of severe/damaging winds, and a few tornadoes are
all possible.
...Southern Plains into the Lower Mississippi Valley/Southeast...
With large-scale upper troughing anchored over the Plains and
central Canada, an embedded mid-level shortwave trough will eject
eastward across the southern/central Plains to the lower/mid MS
Valleys by this evening. Rich low-level moisture continues to spread
northward from TX into southern OK this morning in tandem with a
low-level jet, and this trend should continue downstream into the
lower MS Valley through the day as a warm front lifts northward to a
weak surface low across the Ozarks. Another surface low will remain
over northwest TX, with a dryline extending southwestward to the Big
Bend region.
A strongly unstable airmass exists across the southern Plains to the
ArkLaTex, along and near a slowly retreating/northward-returning
warm front. Elevated supercells are ongoing across western north TX.
This activity is being aided by lift and strong deep-layer shear
associated with the ejecting mid-level shortwave trough, and
low-level warm/moist advection. Current expectations are for these
supercells to continue posing a threat for mainly large to very
large hail through the rest of the morning as they spread
east-northeastward across north TX/southern OK. But, eventual
clustering and a greater damaging wind threat may materialize into
the afternoon as this convection crosses the front and accesses
greater instability across AR and the Ozarks.
Additional surface-based convective development is forecast near the
triple point in north-central TX towards the ArkLaTex this
afternoon, where extreme instability (4000+ J/kg MLCAPE) and very
strong deep-layer shear (50-60+ kt) will support the potential for
multiple intense supercells. Very large to giant hail (2-4+ inches)
may occur with the strongest supercells given the overall very
favorable environment and presence of steep mid-level lapse rates.
Some tornado threat may also exist with these supercells, even
though low-level shear is not forecast to be overly strong.
Numerous to widespread convection across the Mid-South to southern
Appalachians has generally diminished in intensity this morning. In
its wake, airmass recovery is anticipated today across the lower MS
Valley and Mid-South. A convectively reinforced front/outflow
boundary from the morning thunderstorms should attempt to lift
northward some through the day, with the greater instability
forecast across the lower MS Valley where steep mid-level lapse
rates are in place. Convective evolution across these areas through
the evening remains unclear, but multiple rounds of supercells and
multicell clusters capable of producing large hail, scattered to
numerous damaging winds, and perhaps a few tornadoes appear likely.
Less instability is forecast to the north of the ongoing convection
across the TN Valley, but some airmass recovery and severe threat
still appears possible by late afternoon/early evening.
..Gleason/Jewell.. 04/28/2026
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SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0227 AM CDT Tue Apr 28 2026
Valid 301200Z - 011200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Probabilities for severe storms Thursday through Thursday night
appear less than 5 percent.
...Discussion...
Models suggest that an elongated area of lower mid-level heights
will continue a slow east-southeastward progression across much of
the upper Mississippi Valley through northern Atlantic Seaboard,
with an embedded cyclonic circulation redeveloping southeastward
through the Great Lakes region. In its wake split westerlies will
remain broadly confluent across and east of the Rockies, as a short
wave perturbation emerges from the subtropical eastern Pacific.
Further suppression of subtropical ridging centered across southern
Mexico appears probable Thursday through Thursday night, but short
wave ridging may persist to the east of the southern Rockies,
downstream of the subtropical perturbation.
Model spread remains sizable concerning the evolution and motion of
the subtropical perturbation, as well as developments within a
branch of westerlies to the north, emanating from the mid-latitude
Pacific. However, to the east of the Rockies, cool surface ridging
is likely to be maintained across much of the Great Plains and
Mississippi Valley into Southeast. While the frontal zone on the
leading edge of this air mass advances away from much of the
Atlantic Seaboard, it is generally forecast to stall across northern
Florida through the northern Gulf or Gulf coast vicinity. More
uncertainty exists, due to model spread, whether it will make
further progress southward through the Texas Big Bend vicinity and
coastal plain, or redevelop northward a bit, north of the coastal
plain and Pecos Valley.
Forcing for ascent associated with lower/mid-tropospheric warm
advection, downstream of the approaching subtropical perturbation,
may contribute to a corridor of increasing thunderstorm development
above the stable surface-based air across parts of the Permian Basin
and Texas South Plains through much of central Texas by late
Thursday night. However, it remains unclear if elevated
destabilization will become supportive of a risk for severe hail,
before convection becomes increasingly widespread.
Otherwise, the front might provide a general focus for widely
scattered thunderstorm activity near the Gulf coast vicinity, while
destabilization beneath cool mid-level air across the Great Basin
into southern Rockies supports scattered, mostly diurnal
thunderstorm activity.
..Kerr.. 04/28/2026
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Day 4-8 Outlook
Day 4-8 Convective Outlook RESENT 1
NWS Storm Prediction Center Norman OK
0423 AM CDT Tue Apr 28 2026
Valid 011200Z - 061200Z
...DISCUSSION...
Medium-range guidance indicates that the evolving split flow may
maintain a broadly confluent mid-level regime across and east of the
Rockies through this period. While a broad area of lower mid-level
heights remains centered across the Ontario/Quebec and Upper Midwest
through Northeast, it appears that a more prominent blocking
ridge/high may evolve upstream near the British Columbia/Pacific
Northwest coast by late this coming weekend into early next week. A
developing low to its southeast may slowly progress inland across
California into the Southwest, with downstream mid-level ridging
building across the Rockies.
There is considerable model spread concerning embedded short wave
developments, but it appears that potential for stronger convection
will remain generally low for the time of year and confined to parts
of the southern tier of the U.S., perhaps including parts of the San
Joaquin Valley, as well as along a lingering frontal zone near or
just south of the Gulf into southern Atlantic coastal plain. Due to
a combination of low predictability and low severe weather
potential, severe weather probabilities are being maintained at less
than 15 percent through this period.
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