RSS Mesoscale Discussions from Storm Prediction Center
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1103 AM CDT Sat Apr 18 2026
Valid 181630Z - 191200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
ACROSS PARTS OF THE UPPER OHIO VALLEY AND LOWER GREAT LAKES
REGION....
...SUMMARY...
Widely scattered strong to severe thunderstorms capable mainly of
damaging winds will be possible today across the Upper Ohio Valley
and Lower Great Lakes.
...Upper OH Valley...
Latest surface analysis shows a cold front pushing eastward across
western OH, associated with a band of widespread clouds and light
precipitation. Mostly clear skies are present ahead of the front,
where temperatures are warming through the 70s. This will lead to a
corridor of marginal afternoon instability and the potential for
scattered thunderstorm intensification along the front. Forecast
soundings show strong mid-level winds and steep low-level lapse
rates, supportive of strong downdrafts in any vigorous convection.
However, CAM guidance is consistent in showing very few
organized/strong storms through the day. Will maintain the SLGT
risk for the conditional risk of a few damaging wind events, but
with limited confidence.
...TX...
Isolated intense thunderstorms have been ongoing this morning in the
post-frontal regime across central TX. These storms have produced
hail and gusty winds for several hours. It appears likely that this
scenario will shift eastward and weaken early this afternoon as the
primary upper jet moves into AR and away from the region, but will
maintain the MRGL risk area for a few more hours and extend it into
parts of AR/LA.
..Hart/Chalmers.. 04/18/2026
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SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0305 PM CDT Sat Apr 18 2026
Valid 182000Z - 191200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS WITHIN THE
CENTRAL APPALACHIANS INTO THE UPPER OHIO VALLEY VICINITY...AND PARTS
OF CENTRAL TEXAS...
...SUMMARY...
Isolated marginally severe hail is possible in portions of central
Texas. Isolated damaging winds remain possible from the central
Appalachians into the Upper Ohio Valley vicinity.
...20Z Update...
Based on observational trends 15% wind probabilities were removed
from the Upper Ohio Valley vicinity. Wind gusts along with weak,
shallow convection (with little lightning) have generally been in
the 30 kt range with isolated cases of low 40 kt gusts. Isolated
wind damage remains possible, but a more organized threat is not
expected given weak buoyancy downstream. Elsewhere, marginally
severe hail remains possible with isolated, elevated convection in
central Texas.
..Wendt.. 04/18/2026
.PREV DISCUSSION... /ISSUED 1103 AM CDT Sat Apr 18 2026/
...Upper OH Valley...
Latest surface analysis shows a cold front pushing eastward across
western OH, associated with a band of widespread clouds and light
precipitation. Mostly clear skies are present ahead of the front,
where temperatures are warming through the 70s. This will lead to a
corridor of marginal afternoon instability and the potential for
scattered thunderstorm intensification along the front. Forecast
soundings show strong mid-level winds and steep low-level lapse
rates, supportive of strong downdrafts in any vigorous convection.
However, CAM guidance is consistent in showing very few
organized/strong storms through the day. Will maintain the SLGT
risk for the conditional risk of a few damaging wind events, but
with limited confidence.
...TX...
Isolated intense thunderstorms have been ongoing this morning in the
post-frontal regime across central TX. These storms have produced
hail and gusty winds for several hours. It appears likely that this
scenario will shift eastward and weaken early this afternoon as the
primary upper jet moves into AR and away from the region, but will
maintain the MRGL risk area for a few more hours and extend it into
parts of AR/LA.
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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1223 PM CDT Sat Apr 18 2026
Valid 191200Z - 201200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Severe thunderstorms are not expected on Sunday.
...Discussion...
An amplified midlevel trough will move eastward from the Great Lakes
into the Northeast on Sunday, while a related cold front moves off
the Eastern Seaboard and the FL Peninsula. Preceding the trough,
large-scale ascent will support isolated/elevated thunderstorms
across coastal New England into the afternoon. Similarly, a couple
thunderstorms are possible ahead of the front over coastal NC and
farther south over the central/southern FL Peninsula (aided by an
Atlantic sea breeze), though much of this activity may develop
offshore. Farther west over the lower Great Lakes, lapse rates will
quickly steepen beneath the core of the midlevel trough, and
sufficient (albeit weak) buoyancy will support a couple
thunderstorms -- given increasing ascent in the left-exit region of
a midlevel jet.
Finally, isolated/elevated thunderstorms will be possible within a
post-frontal air mass across southwest TX, where weak warm-air
advection will develop amid modestly steep midlevel lapse rates.
..Weinman.. 04/18/2026
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SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0215 PM CDT Sat Apr 18 2026
Valid 201200Z - 211200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Severe storms are not expected on Monday.
...Discussion...
A midlevel trough will move from the Northeast off the New England
coast on Monday, while the tail end of a related cold front
continues southward into the Caribbean Sea. North of the front in
southern FL, diurnal heating amid a moist post-frontal air mass
should support isolated to widely scattered thunderstorms, though
weak buoyancy and limited large-scale forcing for ascent should
limit the severe risk.
Farther west, weak low-level warm advection and modest moisture
return ahead of a low-amplitude midlevel impulse moving into south
TX will support a couple rounds of isolated/elevated thunderstorms
across southwest TX. Isolated thunderstorm potential could spread
further north into central TX late in the period, though confidence
in this scenario is currently low. Additional diurnal thunderstorms
are possible across the Southwest as the midlevel moisture impinges
on the region, with most of this activity expected over the higher
terrain.
..Weinman.. 04/18/2026
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