RSS Mesoscale Discussions from Storm Prediction Center
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1151 AM CDT Tue Apr 28 2026
Valid 281630Z - 291200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS NORTH
TEXAS...
...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 to Lower Mississippi Valley/Southeast...
Have upgraded portions of North Texas to a Moderate Risk for what is
anticipated to be a semi-focused sub-regional corridor of supercells
including very large hail potential along with some damaging
wind/tornado risk centered on mid-afternoon through
early/mid-evening.
First, a loosely organized complex of storms continues to progress
east-northeastward along the Red River of southeast
Oklahoma/northeast Texas and broader parts of eastern Oklahoma at
late morning. Additional increasingly surface-based development
seems probable on this near-frontal zone and associated moist axis
and thermal gradient that extends east-northeastward to the
Mid-South/ArkLaMiss. This may include supercells as well as the
possibility of an upscale-growing complex. Other initially elevated
severe storms are expected to continue and increase today from
northeast Oklahoma across the Ozarks toward parts of the
Mid-South/Mississippi Valley. Large hail is the initial risk, but a
surface-based storm risk could develop pending boundary layer
warming.
Broadly speaking outside on ongoing storms, a strongly unstable
airmass exists across the southern Plains to the ArkLaTex, along and
near a slowly retreating/northward-returning warm front. This is
beneath relatively strong winds aloft, particularly in
mid/high-levels based on morning upper-air data. Additional intense
surface-based convective development is forecast near the triple
point in north-central Texas 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.
Additional severe storms are expected as far east as Mississippi and
Alabama today -- see Mesoscale Discussion 594 for short-term
details. An additional secondary round of upscale-growing storms
with increasing damaging wind potential could also move into this
same region late today, or more so tonight.
..Guyer/Chalmers.. 04/28/2026
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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1230 PM CDT Tue Apr 28 2026
Valid 291200Z - 301200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN A CORRIDOR
FROM SOUTH-CENTRAL TEXAS INTO PARTS OF THE SOUTHEAST...AND ALSO FROM
THE ALLEGHENY PLATEAU INTO THE MID ATLANTIC...
...SUMMARY...
Widely scattered strong to severe storms may impact a corridor from
south of the Texas Big Bend through the north central Gulf Coast
vicinity Wednesday afternoon into evening, with additional strong
storms posing at least some risk for severe weather across the
Allegheny Plateau into the Mid Atlantic.
...Lower Rio Grande Valley into parts of the Southeast...
Outflow associated with extensive D1/Tuesday convection is forecast
by most guidance to weaken and become increasingly ill defined near
the northwest/north-central Gulf Coast through the day, with the
trailing primary cold front extending from south-central TX into the
Southeast by afternoon.
Details of convective evolution through the day/evening remain
unclear, but with moderate midlevel flow and deep-layer shear
overspreading residual moderate to strong buoyancy, the environment
will again conditionally favor an organized severe threat through
the day and evening.
Some guidance (both regional/global and CAMs) suggests that a
low-amplitude midlevel vorticity maximum may emerge from northern
Mexico and initiate storm development across parts of the Hill
Country and central TX, during the morning, with at least isolated
development also possible into parts of the ArkLaTex/lower MS Valley
and Southeast, near the cold front and any remnant outflow boundary.
Initial discrete development could pose a threat of isolated large
hail, with a conditional very large hail risk with any robust
supercell. With relatively unidirectional deep-layer westerly flow,
one or more eastward-moving clusters may evolve with time and track
in the vicinity of the cold front, posing a threat of at least
isolated wind damage. Parts of the region may require higher severe
probabilities, once mesoscale details come into better focus with
time.
...Allegheny Plateau into the Mid Atlantic...
Within a broad large-scale mid/upper-level trough covering much of
the eastern CONUS, a vigorous shortwave trough is forecast to move
from the Midwest to the Mid Atlantic on Wednesday. A surface low
will move from near the upper OH Valley toward the Delmarva region,
as a trailing cold front moves through parts of the central/southern
Appalachians into parts of VA/MD and the Carolinas.
Potential for substantial destabilization in the wake of morning
precipitation remains uncertain from parts of the Allegheny Plateau
into the Mid Atlantic. Ascent related to the approaching shortwave
trough and favorable wind profiles could support development of
strong clusters or marginal supercells, if sufficient
destabilization occurs. Some threat for damaging wind, a brief
tornado or two, and perhaps isolated hail could develop, though the
magnitude and coverage of these threats remain too uncertain for a
categorical upgrade at this time. Higher severe probabilities may
eventually be needed, if confidence increases in the development of
sustained supercells and/or organized clusters.
..Dean.. 04/28/2026
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