RSS Mesoscale Discussions from Storm Prediction Center
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1229 AM CDT Wed Mar 11 2026
Valid 111200Z - 121200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE LOWER
MISSISSIPPI VALLEY...ACROSS THE TENNESSEE/OHIO VALLEY INTO THE
MIDDLE ATLANTIC...
...SUMMARY...
Isolated to scattered severe thunderstorms are expected today from
the ArkLaTex and Lower Mississippi Valley northeastward through the
Ohio Valley and Mid-Atlantic.
...Ohio Valley/Middle Atlantic...
Northern-stream trough is digging east-southeast across the northern
Rockies/High Plains early this morning and should advance into the
upper MS Valley by 18z as a 500mb speed max translates through the
base of the trough, then increases in intensity as it moves across
lower MI during the afternoon. Large-scale height falls will
overspread the Great Lakes/OH-TN Valley region as southwesterly flow
strengthens across the downstream warm sector. Latest model guidance
suggests the sharp cold front associated with this feature will
extend across lower MI-central IL-northern MO at the start of the
period. This boundary will serve as a primary focus for thunderstorm
development through the period. By mid day, the front will have
surged into northwest OH-central IN and modest boundary layer
heating is expected across the warm sector downstream.
Current thinking is modest destabilization will be noted across much
of the OH/TN Valley such that MLCAPE values should be on the order
of 1500 J/kg within a strongly sheared environment. Forecast
soundings support this and supercells are expected to develop, in
addition to possible line segments and clusters. Large hail is
possible with supercells, along with damaging winds and a risk for a
few tornadoes. This activity will spread east toward the Middle
Atlantic by late afternoon.
...Gulf States...
Positive-tilt short-wave trough is shifting east across west
TX/northeast Mexico. However, this feature is expected to become
more negative tilt by late afternoon as it ejects toward the lower
Sabine River Valley. Seasonally cool 500mb temperatures are noted
with this feature and a focused 70kt midlevel jet is forecast to
translate along the Gulf coast during the latter half of the period.
Left-exit region of this jet will encourage ascent/deep convection.
Latest guidance suggests a surface low may evolve in response,
tracking from the upper TX coast, across southern LA into southern
MS by 12/06z. Some LLJ response is also expected which should aid
organized thunderstorms across the southern Gulf states. Strong
shear favors severe winds along with a risk for tornadoes. Some
consideration was given to increasing severe probabilities ahead of
this feature. This may be done in later outlooks if conditions
continue to evolve toward an organized squall line.
..Darrow/Lyons.. 03/11/2026
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SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1231 AM CDT Wed Mar 11 2026
Valid 121200Z - 131200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
A couple of strong thunderstorms producing gusty winds are possible
across parts of the Southeast on Thursday morning into early
afternoon. However, severe thunderstorm potential appears low.
...Southeast...
An upper trough from the Great Lakes to the central Gulf Coast will
pivot east, moving offshore the Atlantic Seaboard by late
Thursday/early Friday. Thursday morning, a cold front will extend
south/southwest from the Mid-Atlantic coast to southern AL.
Scattered thunderstorms will be ongoing ahead of the front within a
moist warm sector, mainly from the central portions of the Carolinas
into southwest GA and the FL Panhandle. Mid and low-level lapse
rates are forecast to remain modest (6-6.5 C/km), and limited
heating downstream of the front through midday/early afternoon will
be stunted by cloudiness. As a result, instability is expected to
remain modest (500-750 J/kg MLCAPE). Deep-layer westerly flow
parallel to the front will remain fairly robust, with 30-50 kt from
850-500 mb. Coupled with weak instability, a few stronger storms
producing mainly gusty winds will be possible across portions of
northern FL into southeast GA, and perhaps portions of coastal SC.
The front should move offshore by mid-afternoon (arcing
southwestward across north FL and the eastern Gulf). Overall, severe
thunderstorm potential appears limited.
..Leitman.. 03/11/2026
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SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0144 AM CDT Wed Mar 11 2026
Valid 131200Z - 141200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Severe thunderstorms are not expected on Friday.
...Synopsis...
Broad upper troughing will persist over much of the U.S. on Friday.
At the surface, a cold frontal intrusion into the Gulf of America
will leave a dearth of boundary layer moisture east of the Rockies,
and a cool/dry/stable airmass will be in place. The exception will
be across south FL where a seasonally moist boundary layer will
persist south of the diffuse surface boundary. Isolated
thunderstorms will be possible across the southern Peninsula.
However, modest vertical shear, poor lapse rates, and a lack of
large-scale ascent will preclude severe thunderstorm potential.
..Leitman.. 03/11/2026
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Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0252 AM CDT Wed Mar 11 2026
Valid 141200Z - 191200Z
...DISCUSSION...
...Days 4-6/Sat-Mon...
An upper trough will begin to deepen as it moves over the northern
Rockies and into the northern/central High Plains on
Saturday/Saturday night. As this occurs, a lee cyclone will deepen
as it shifts east across the central Plains toward the MO Valley by
early Sunday. Modified Gulf moisture will return northward in
response to increasing southerly low-level flow ahead of the surface
cyclone and attendant cold front. Medium range guidance is in fairly
good agreement that any deeper/higher quality moisture will remain
confined to east TX and the immediate Gulf coast on Sunday. With
northward extent into the Mid-South, Mid-MS and Lower OH, and TN
Valleys, 50s F dewpoints appear more likely. The upper trough will
intensify and shift east across the Midwest and south-central U.S.
on Sunday, but stronger flow aloft will remain displaced from better
quality moisture return. While some severe potential could develop
from east TX into the Lower OH/TN Valleys as a strong cold front
tracks east across the central U.S. on Sunday, probabilities appear
less than 15 percent at this time.
This system will shift east across the eastern U.S. on Monday,
though any severe potential along the East Coast appears low at this
time as the primary forcing for ascent lags behind the surface
front.
...Days 7-8/Tue-Wed...
An amplified upper ridge will build across the western U.S. during
the end of Tuesday and Wednesday while upper troughing persists
across the East. Surface high pressure and the prior cold frontal
passage into the Gulf will leave a stable and dry airmass in place,
precluding severe potential.
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