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 Sat Mar 21 2026
Valid 211200Z - 221200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTHERN APPALACHIAN REGION...
...SUMMARY...
Isolated strong to severe thunderstorms may produce hail to near 1
inch diameter this afternoon and evening across the southern
Appalachian region.
...Southern Appalachians...
Very strong midlevel anticyclone remains anchored over the
southwestern CONUS. This is forcing meaningful short waves across
the northern Rockies/high Plains before digging southeast toward the
eastern portions of the United States. Early this morning,
water-vapor imagery depicts one of these features digging southeast
across eastern SD/NE. By the start of the period this short wave
will extend across IL/southeast MO/northeast AR, then it will
advance into KY/TN by early afternoon.
At the surface, a weak boundary that is draped across VA-northern KY
will gradually lift north and become somewhat diffuse west of the
higher terrain. South of this wind shift, modest boundary-layer
heating will be noted across the Carolinas into the TN Valley such
that 0-3km lapse rates should exceed 7 C/km by peak heating.
Forecast soundings suggest convective temperatures will be
approached, or breached by 21z as temperatures rise through the
upper 70s to near 80F across southeast KY/eastern TN. While
low-level convergence is expected to be somewhat weak, orographic
influences will contribute to the potential for isolated
thunderstorm development ahead of the short wave. Forecast midlevel
flow is expected to be around 30-35kt across this region at 500mb,
so deep-layer shear may prove adequate for a few supercells. If
robust convection develops in this environment then hail on the
order of 1 inch could be noted with the strongest storms. This
activity will spread southeast into the western Carolinas as the
short wave advances downstream. The primary concern for hail will be
during the afternoon/evening hours.
..Darrow/Wendt.. 03/21/2026
Read more
SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0101 AM CDT Sat Mar 21 2026
Valid 221200Z - 231200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE OHIO VALLEY...
...SUMMARY...
Severe thunderstorms with large hail and severe wind gusts are
expected on Sunday afternoon and evening across parts of the Ohio
Valley.
...Ohio Valley/Mid Mississippi Valley...
At mid-levels on Sunday, an amplifying trough will move quickly
east-southeastward across the north-central U.S, as an associated
jet streak translates eastward into the southern Great Lakes. At the
surface, a cold front will advance southward into the Ohio Valley.
South of the front, moderate instability will develop across a moist
airmass by early afternoon, with surface dewpoints in the lower to
mid 60s F. Warming surface temperatures and increasing low-level
convergence will result in convective initiation along parts of the
front during the mid to late afternoon. Storm coverage is forecast
to gradually increase as several clusters or line segments with a
severe threat move southeastward across the Ohio Valley during the
late afternoon and early evening.
During the afternoon from Cincinnati to Pittsburgh, forecast
soundings gradually increase MLCAPE in the 1500 to 2000 J/kg range.
Forecasts just ahead of the front suggest that winds will be veered
to the southwest near the surface, but that strong speed shear will
exist in the lower to mid-levels. 0-6 km shear is forecast to range
from 40 to 50 knots, which should be favorable for severe
thunderstorm development. 700-500 mb lapse rates in the 7.0 to 7.5
C/km range should support supercells with large hail. The supercell
threat is expected to be greatest early in the event, when cells are
more likely to be discrete. A threat for severe wind gusts is also
expected. The wind-damage threat should be concentrated along short
line segments that form in the late afternoon and early evening. A
marginal tornado threat will also be possible.
Further west-southwest into the lower Ohio Valley and mid
Mississippi Valley, the models are forecasting a stout capping
inversion to the south of the front over much of the warm sector.
Near the front in the early evening, the cap is forecast to weaken.
This combined with increasing low-level convergence near the front
should be enough for isolated convective initiation. A marginal
threat for hail and severe wind gusts would be possible with the
stronger cells that can initiate and persist.
..Broyles.. 03/21/2026
Read more
SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0211 AM CDT Sat Mar 21 2026
Valid 231200Z - 241200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CAROLINAS AND GEORGIA...
...SUMMARY...
An isolated severe threat is expected on Monday across parts of the
Carolinas and Georgia.
...Carolinas/Georgia...
An upper-level trough will move eastward to near the Eastern
Seaboard on Monday. At the surface, a cold front is forecast to move
through the Carolinas, and should be positioned from central Georgia
into central South Carolina by Monday afternoon. Ahead of the front,
surface dewpoints in the upper 50s and lower 60s F will contribute
to weak destabilization. Isolated thunderstorms are expected to
develop near the front and move east-southeastward toward the
Atlantic coast during the mid to late afternoon. 0-6 km shear in the
30 to 35 knot range, along with steep low-level lapse rates may be
enough for a marginal wind-damage threat.
..Broyles.. 03/21/2026
Read more
Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0329 AM CDT Sat Mar 21 2026
Valid 241200Z - 291200Z
...DISCUSSION...
...Tuesday/Day 4 to Thursday/Day 6...
An upper-level trough is forecast to move eastward into the western
Atlantic from Tuesday into Wednesday, as a surface high moves
eastward across the eastern U.S. A dry airmass is forecast across
most of the U.S., which should be unfavorable for thunderstorms in
most areas.
On Thursday, a low is forecast to develop in the northern U.S., as
low-level moisture returns quickly northward into the parts of the
Great Plains and Mississippi Valley. Thunderstorms will be possible
across this unstable airmass, mainly Thursday night, along the
southern edge of a passing mid-level jet streak. The greatest
potential for severe thunderstorms is expected from the mid
Mississippi Valley into the Ohio Valley along and near a cold front.
At this time, the amount of spread concerning potential outcomes is
substantial. An area may need to be added once model solutions begin
to agree more, and confidence increases concerning where the
greatest severe threat will be.
...Friday/Day 7 and Saturday/Day 8...
On Friday, the front is forecast to move southward across the
Tennessee Valley, where isolated to scattered strong thunderstorms
will be possible during the day. The front is forecast to move
southward to near the Gulf Coast by Saturday. Isolated storms would
again be possible near the front. Although the current thinking is
that any severe threat will be marginal on Friday and Saturday,
uncertainty is substantial due to the extended range in the forecast
period.
Read more
