RSS Mesoscale Discussions from Storm Prediction Center
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1108 AM CDT Thu Mar 26 2026
Valid 261630Z - 271200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MIDWEST/OHIO VALLEY...
...SUMMARY...
Scattered severe thunderstorms are expected this afternoon and
evening across parts of the Midwest and Ohio Valley. Large to very
large hail, a few tornadoes, and severe/damaging winds all appear
likely.
...Mid Mississippi Valley into the Midwest/Ohio Valley...
Water-vapor imagery late this morning shows a flattened upper ridge
centered over the south-central U.S. with strong westerly
mid/upper-level flow across the Midwest/Great Lakes. A mid-level
shortwave trough over the northern Rockies will move quickly
east-southeast into the Upper Midwest and act to suppress mid-level
heights across the Midwest/Great Lakes through tonight. Surface
analysis this morning showed a weak low over eastern IA with a
west-east oriented frontal zone extending east across the southern
Great Lakes. If a weak surface reflection is maintained and
develops east across the southern Great Lakes through this evening,
it may notably influence severe potential within a focused corridor
late this afternoon through this evening. The aforementioned front
will gradually push south and serve as the primary impetus for storm
development.
Beneath a capping inversion, moistening will continue with surface
dewpoints rising into the 56-62 deg F range from the mid MS Valley
east into western PA. Upwards of 500-1500 J/kg MLCAPE is likely by
mid afternoon south of the front. A belt of strong, westerly 50-65
kt 700-mb flow is forecast to move from IA and expand spatially
across the warm sector through early evening. This increase in flow
will act to elongate hodographs despite mainly veered southwesterly
surface flow. Recent convection-allowing model guidance varies
considerably on the depiction of cellular versus mostly linear
clusters evolving in the first few hours of the convective life
cycle. Time-lagged HRRR would imply a more spatially and
numerically extensive supercell hail and tornado risk than most of
the 12z HREF HRW members showing less risk of these hazards. The
tornado risk could focus with potential supercells near a weak low
and where surface flow would locally back to southerly. However,
confidence is muted regarding this specific scenario.
Regardless, current expectations are for thunderstorms to quickly
develop along the length of the front from central IL eastward into
IN, southern Lower MI, and northern OH by 19-22Z as diurnal heating
erodes lingering convective inhibition. A mix of supercells and
organized linear clusters will evolve with large to very large hail
possible. A fairly quick transition to more linear structures
appears likely given the frontal forcing, with an increasing threat
for scattered to numerous severe/damaging winds as one or more
clusters spreads east-southeastward across much of the OH Valley
into western/central PA through the late afternoon and evening.
Given the forecast strength of the low to mid-level flow, isolated
gusts of 75+ mph may occur. There is a threat for a few tornadoes
as well with both supercells and embedded mesocirculations within
the linear clusters.
Farther west across the mid MS Valley (MO into eastern KS), there is
lower confidence in warm sector thunderstorm development this
afternoon and evening due to the presence of a stronger cap.
However, elevated convection may occur along/behind the cold front
this evening, with strong deep-layer shear and sufficient MUCAPE
conditionally supporting supercells with mainly a threat for large
hail.
..Smith/Hart.. 03/26/2026
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SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Thu Mar 26 2026
Valid 262000Z - 271200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM CENTRAL
ILLINOIS EASTWARD INTO INDIANA...OHIO...AND EXTREME WESTERN
PENNSYLVANIA...
...SUMMARY...
Scattered severe thunderstorms are expected late this afternoon and
evening across parts of the Midwest and Ohio Valley. Large to very
large hail, a few tornadoes, and damaging winds will all be
possible.
...From northern MO across IL, IN, OH and into western PA...
The air mass continues to heat and destabilize this afternoon ahead
of a cold front, which extends from southern Lower MI westward
toward the MO/IA border at 20Z. The air mass remains capped for
surface-based parcels, but clouds will continue to develop along the
boundary with eventual severe storm development along and behind
much of the front. Stronger heating / larger temp-dew spreads
suggest a lesser tornado risk for western areas, while farther east
conditions appear a bit more favorable with more low-level SRH /
with lake breeze effects. GPS water vapor sensors also show higher
values of PWAT over southern IN and KY which will lift northeastward
across IN/OH/PA later today.
In all areas, steep lapse rates aloft and strong deep-layer shear
beneath northwest flow aloft will support supercells producing
damaging hail. This may occur in both elevated cells north of the
undercutting front, and ahead of it.
For more information see mesoscale discussion #0291.
..Jewell.. 03/26/2026
.PREV DISCUSSION... /ISSUED 1108 AM CDT Thu Mar 26 2026/
...Mid Mississippi Valley into the Midwest/Ohio Valley...
Water-vapor imagery late this morning shows a flattened upper ridge
centered over the south-central U.S. with strong westerly
mid/upper-level flow across the Midwest/Great Lakes. A mid-level
shortwave trough over the northern Rockies will move quickly
east-southeast into the Upper Midwest and act to suppress mid-level
heights across the Midwest/Great Lakes through tonight. Surface
analysis this morning showed a weak low over eastern IA with a
west-east oriented frontal zone extending east across the southern
Great Lakes. If a weak surface reflection is maintained and
develops east across the southern Great Lakes through this evening,
it may notably influence severe potential within a focused corridor
late this afternoon through this evening. The aforementioned front
will gradually push south and serve as the primary impetus for storm
development.
Beneath a capping inversion, moistening will continue with surface
dewpoints rising into the 56-62 deg F range from the mid MS Valley
east into western PA. Upwards of 500-1500 J/kg MLCAPE is likely by
mid afternoon south of the front. A belt of strong, westerly 50-65
kt 700-mb flow is forecast to move from IA and expand spatially
across the warm sector through early evening. This increase in flow
will act to elongate hodographs despite mainly veered southwesterly
surface flow. Recent convection-allowing model guidance varies
considerably on the depiction of cellular versus mostly linear
clusters evolving in the first few hours of the convective life
cycle. Time-lagged HRRR would imply a more spatially and
numerically extensive supercell hail and tornado risk than most of
the 12z HREF HRW members showing less risk of these hazards. The
tornado risk could focus with potential supercells near a weak low
and where surface flow would locally back to southerly. However,
confidence is muted regarding this specific scenario.
Regardless, current expectations are for thunderstorms to quickly
develop along the length of the front from central IL eastward into
IN, southern Lower MI, and northern OH by 19-22Z as diurnal heating
erodes lingering convective inhibition. A mix of supercells and
organized linear clusters will evolve with large to very large hail
possible. A fairly quick transition to more linear structures
appears likely given the frontal forcing, with an increasing threat
for scattered to numerous severe/damaging winds as one or more
clusters spreads east-southeastward across much of the OH Valley
into western/central PA through the late afternoon and evening.
Given the forecast strength of the low to mid-level flow, isolated
gusts of 75+ mph may occur. There is a threat for a few tornadoes
as well with both supercells and embedded mesocirculations within
the linear clusters.
Farther west across the mid MS Valley (MO into eastern KS), there is
lower confidence in warm sector thunderstorm development this
afternoon and evening due to the presence of a stronger cap.
However, elevated convection may occur along/behind the cold front
this evening, with strong deep-layer shear and sufficient MUCAPE
conditionally supporting supercells with mainly a threat for large
hail.
Read more
SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1126 AM CDT Thu Mar 26 2026
Valid 271200Z - 281200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Isolated thunderstorms are expected from the Ohio Valley into the
Carolinas Friday morning into the afternoon, but severe thunderstorm
potential appears limited.
...Synopsis...
An upper trough will pivot across the eastern U.S. on Friday.
Stronger deep-layer west/southwesterly flow will remain focused
across portions of the Midwest/Great Lakes into the Northeast.
Meanwhile, at the surface a cold front extending from the
Mid-Atlantic to the southern Plains will develop south/southeast
through the period, moving offshore by early Saturday. Ahead of the
front, modest boundary-layer moisture (upper 50s to low 60s F
dewpoints) will be in place across the VA Piedmont into the
Carolinas. Steep midlevel lapse rates around 6.5-7 C/km are expected
across the region, and will aid in weak destabilization near the
front. NAM and RAP forecast soundings maintain capping across VA
before the front moves through around midday. Further south across
portions of NC, stronger heating may allow for sufficient mixing and
erosion of weak midlevel capping. A couple of surface-based
thunderstorms could develop near the front and produce gusty winds.
However, overall severe potential is expected to be limited by weak
instability and mostly anafrontal convective processes.
Further west, isolated thunderstorms will be ongoing Friday morning
near/just behind the cold front into the Ohio Valley. This activity
should diminish with time and southward extent through the day.
..Leitman.. 03/26/2026
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SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0144 PM CDT Thu Mar 26 2026
Valid 281200Z - 291200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Isolated thunderstorms will be possible Saturday afternoon across
portions of the Florida peninsula, but the potential for severe
thunderstorms is low.
...Synopsis...
Northwesterly flow aloft will deamplify as an upper trough moves
offshore the eastern U.S. on Saturday. At the surface, a cold front
will extend across the northern Gulf into the FL Peninsula Saturday
morning. As the front develops southward through the day, isolated
thunderstorms are possible across portions of the central/southern
FL Peninsula. Modest instability and weak vertical shear will
preclude severe thunderstorm potential. Elsewhere, a dry and stable
airmass will reside across much of the CONUS in the wake of the
prior cold frontal passage.
..Leitman.. 03/26/2026
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