RSS Mesoscale Discussions from Storm Prediction Center
SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0104 AM CDT Mon Apr 13 2026
Valid 141200Z - 151200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF IOWA INTO NORTHERN ILLINOIS AND SOUTHERN WISCONSIN...
...SUMMARY...
Isolated to scattered severe thunderstorms are expected on Tuesday
and Tuesday night from the Southern Plains to the Great Lakes. Large
to very large hail, a few tornadoes, and damaging wind gusts will be
possible, particularly across parts of eastern Iowa, northern
Illinois, and southern Wisconsin. Additional strong storms, mainly
producing strong wind gusts, will be possible across parts of the
Northeast.
...Synopsis...
A broad swath of enhanced deep-layer southwesterly flow will
overspread the southern High Plains to the Great Lakes on Tuesday.
An upper shortwave trough over the Great Basin will slowly pivot
east through the period, emerging over the central/southern High
Plains by Wednesday morning. A weak shortwave impulse is also
forecast to move across the northern Plains and Upper Midwest. At
the surface, low pressure will be centered over the Mid-MO Valley
for much of the period, with a warm front extending east/northeast
from north-central IA into southern WI and central Lower MI.
Meanwhile, a dryline will extend southwest across eastern KS into
western TX. Ahead of these boundaries, a seasonally moist airmass
will be in place, with mid-60s dewpoints common. The aforementioned
surface boundaries will become a focus severe thunderstorm
development Tuesday afternoon into the nighttime hours.
...Mid-MS Valley and Great Lakes vicinity...
A severe risk is expected to develop by late afternoon within the
warm frontal zone from Iowa into northern IL/southern WI in a
persistent warm advection regime. While height tendencies are
forecast to remain mostly neutral, low-level convergence along the
boundary and a glancing influence from a weak shortwave impulse
migrating across the northern Plains into northern MN/Upper MI
should provide focused ascent. A southwesterly 850-700 mb jet is
also forecast to increase across the region by late afternoon into
evening. Cool temperatures aloft (around -16 C at 500 mb) and steep
midlevel lapse rates atop a moist boundary layer will support MLCAPE
around 2000-3000 J/kg amid elongated/straight hodographs. As a
result, large to very large hail will be possible with initial
supercell thunderstorms. Storm motion and southwesterly deep-layer
flow may result in convection moving to the cool side of the warm
front. Even so, elevated storms will pose a risk for significant
hail. With time, and as the low-level jet increases during the
evening, convection may consolidate/grow upscale into one or most
bowing segments and progress eastward into Lower MI/IN/OH, posing a
continued risk for hail and an increasing risk for damaging wind
gusts.
Any supercells that develop and can be sustained within the warm
sector will also pose a risk for a few tornadoes (some strong), very
large hail and damaging gusts.
...Southern Plains into eastern KS/western MO...
Moderate destabilization is forecast along the surface dryline by
afternoon. Strong heating along/just west of the dryline will
promote mixing, while low-level confluence and subtle height falls
(by 21-00z) provide sufficient forcing for ascent for isolated
thunderstorm development. Supercell wind profiles will be present
amid steep midlevel lapse rates and elongated hodographs. Large to
very large hail, locally strong wind gusts and a couple of tornadoes
will be possible. Storms should develop northward during the evening
into eastern KS and western MO as the low-level jet increases.
...Northeast...
Rounds of thunderstorms are expected during the afternoon and
evening within a warm advection regime. MLCAPE should increase to
around 1000 J/kg within a moistening low-level airmass. Strong
deep-layer westerly flow and steepening low-level lapse rates will
support isolated strong wind gusts across the region.
..Leitman.. 04/13/2026
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SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0216 AM CDT Mon Apr 13 2026
Valid 151200Z - 161200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTION OF
THE SOUTHERN PLAINS INTO SOUTHERN WISCONSIN...
...SUMMARY...
Severe thunderstorms posing a risk for large hail and strong wind
gusts will be possible across portions of the southern Plains toward
the Great Lakes on Wednesday afternoon and evening.
...Southern Plains to Great Lakes...
An upper trough will move from the Plains to the MS Valley vicinity
on Wednesday. As associated corridor of enhanced southwesterly
deep-layer flow will overspread a moist/unstable airmass ahead of a
surface dryline. The southern Plains portion of the dryline will not
move too much on Wednesday. However, the northern extent of this
boundary will intersect a weak surface low moving from the Lower MO
Valley toward Lake Michigan. This portion of the boundary will
advance eastward toward the MS River during the evening/overnight
hours.
Areas of showers and thunderstorms may be ongoing across portions of
the region Wednesday morning. As a result, there is uncertainty
regarding how the boundary layer may recover/destabilize during the
afternoon. Nevertheless, at least pockets of moderate
destabilization (1000-2000 J/kg MLCAPE) are expected within a
corridor along and east of the surface boundary. Effective shear
magnitudes greater than 40 kt will be sufficient for organized
convection, with large hail and strong wind gusts being the primary
hazards.
..Leitman.. 04/13/2026
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Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0344 AM CDT Mon Apr 13 2026
Valid 161200Z - 211200Z
...DISCUSSION...
...Day 4/Thu - Mid-South vicinity...
An upper shortwave trough will develop northeast from eastern OK/TX
to the central/southern Appalachians on Thursday. Convection is
likely to be ongoing from the Mid-MS/Lower OH Valley to the ArkLaTex
region Thursday morning. This will likely temper downstream
destabilization (and overall severe risk), but a few strong storms
are possible across the Mid-South vicinity.
...Day 5/Fri - Southern Plains to Iowa...
Medium range guidance has been consistently showing an upper trough
over the western U.S. developing eastward toward the High Plains
Friday/Friday night. As this occurs, increasing deep-layer
southwesterly flow will overspread a seasonally moist and unstable
airmass. A lee low will deepen over the central/southern High
Plains, with a dryline extending across western OK/TX during the
afternoon. By evening and into the overnight hours, a cold front
will spread southeast across the central/southern Plains and Lower
MO Valley. This pattern will support a risk of severe storms across
the warm sector from OK to IA.
...Days 6-8/Sat-Mon...
Some severe risk may persist into Saturday as a surface low deepens
over the Great Lakes and the cold front from the Day 5/Friday period
continues to sweep east across the Midwest to the Lower MS Valley,
becoming oriented across the Appalachians by Sunday morning. Severe
potential may depend on how convection on Friday evolves and impacts
the downstream airmass heading into Saturday morning, resulting in
low predictability at this time. Strong surface high pressure will
build across the Plains in the wake of the cold front, and Gulf
moisture will become cut-off as the front pushes well south into the
Gulf Basin. This should bring a reprieve from severe thunderstorm
potential Sunday into Monday as surface high pressure envelops much
of the CONUS east of the Rockies by the end of the period.
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