RSS Mesoscale Discussions from Storm Prediction Center
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1251 AM CDT Tue May 12 2026
Valid 121200Z - 131200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
FLORIDA PENINSULA AND PARTS OF THE MIDWEST/GREAT LAKES...
...SUMMARY...
Severe storms will be possible at least on an isolated basis across
parts of the Florida Peninsula today, and potentially parts of the
Great Lakes to Lower Missouri Valley and south-central Plains late
this afternoon and early evening.
...Florida Peninsula...
A front will settle southward today in advance of a low-latitude
shortwave trough crossing the northeast Gulf. A moist and
potentially unstable environment will exist during the afternoon,
especially across the central Peninsula where MLCAPE could exceed
1500 J/kg, although early day clouds and convection near/south of
the front leads to some uncertainty regarding destabilization
details. Regardless, storms should steadily increase in coverage and
intensity through late morning into the afternoon, initially across
the north-central Peninsula, maximizing toward the east coast,
although additional storms may move inland from the Gulf.
Strengthening mid/high-level winds will support upwards of 30-40 kt
effective shear and fairly long/semi-straight hodographs, which
could yield some transient supercell structures pending sufficient
destabilization. Damaging winds and hail will be possible at least
on an isolated basis, and a tornado could occur as well,
particularly near the effective front. A greater confidence in
destabilization and the possibility of more sustained
storms/supercells could warrant a Slight Risk upgrade.
...Wisconsin/Lake Michigan to south-central Plains...
A shortwave trough over the Canadian Prairies will dig southeastward
and amplify toward the Upper Great Lakes through this evening, with
a cold front moving southeastward across these regions. Low-level
moisture will be limited near/ahead of the front, but advection may
be sufficient to counteract mixing to allow surface dewpoints to
reach the 50s F by late afternoon/early evening.
In tandem with the strongest forcing for ascent, and in vicinity of
the surface low/front, isolated to widely scattered development is
initially expected, and most probable, late in the afternoon/early
evening across eastern Wisconsin, with additional storms possible
farther southwest near the front across Illinois/Missouri and
potentially into southeast Kansas/northeast Oklahoma. Where storms
develop/sustain, steep lapse rates and strong west-northwesterly
flow aloft could yield some severe storms capable of hail/damaging
wind.
...Western Oregon/southern Washington...
A few stronger storms with gusty winds and/or sub-severe hail could
develop late in the afternoon and evening regionally in advance an
upper-level trough approaching the coastal Pacific Northwest.
Strengthening deep-layer winds and steepening lapse rates could
plausibly yield some stronger storms, although the potential for
sustained/organized severe storms is currently expected to remain
low.
..Guyer/Weinman.. 05/12/2026
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SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1239 AM CDT Tue May 12 2026
Valid 131200Z - 141200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE OHIO VALLEY...CENTRAL APPALACHIANS...NORTHERN ROCKIES AND GREAT
BASIN...
...SUMMARY...
Thunderstorms with isolated severe wind gusts are expected on
Wednesday across parts of the Ohio Valley, central Appalachians,
northern Rockies and Great Basin. Hail will also be possible in
parts of western Montana.
...Ohio Valley/Central Appalachians...
An upper-level trough will move east-southeastward across the Great
Lakes on Wednesday, as an associated mid-level jet streak translates
southeastward into the Ohio Valley. At the surface, a low will move
eastward across southwestern Ontario as a cold front advances
east-southeastward into the central Appalachians. Ahead of the
front, surface dewpoints in the lower to mid 50s F will contribute
to weak instability as surface temperatures warm during the day.
Increasing low-level convergence near the front will lead to
scattered thunderstorm development, with additional storms forming
due to topographic forcing in the central Appalachians. Ahead of the
front, low to mid-level lapse rates are forecast to become steep in
the afternoon peaking in the 7 to 7.5 C/km range, which should
support a threat for isolated severe wind gusts.
...Northern Rockies/Great Basin...
At mid-levels, a shortwave trough will move through the northwestern
U.S. on Wednesday as a 60 to 80 knot jet streak passes eastward into
the northern Rockies. At the surface, a trough will develop from
western Montana southward into Idaho and Utah, ahead of a cold front
passing through the Pacific Northwest. Near the surface trough, an
axis of instability will be in place by afternoon as surface
temperatures warm into the 80s F. In response, thunderstorms will
form in the higher terrain from western Montana southward into the
deserts of eastern Idaho and northern Utah. Near the instability
axis, low to mid-level lapse rates will be very steep likely
exceeding 9 C/km. This will support a threat for isolated severe
wind gusts. Hail could also occur in the northern Rockies.
..Broyles.. 05/12/2026
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SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0200 AM CDT Tue May 12 2026
Valid 141200Z - 151200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NORTH-CENTRAL OKLAHOMA...CENTRAL KANSAS AND FAR SOUTHERN NEBRASKA...
...SUMMARY...
Thunderstorms with isolated severe gusts and hail will be possible
on Thursday from parts of north-central Oklahoma into central Kansas
and far southern Nebraska.
...North-central Oklahoma/Central Kansas/Far Southern Nebraska...
At mid-levels, a shortwave ridge will move eastward into the Ozarks
and mid to upper Mississippi Valley on Thursday, as a shortwave
trough passes through the Great Plains. Ahead of the trough over the
southern and central Plains, low-level moisture advection will take
place. Surface dewpoints are forecast to increase into the 60s F
over much of Oklahoma northward into central and northern Kansas.
Along this corridor, moderate instability is expected to develop by
afternoon with MLCAPE peaking in the 1500 to 2500 J/kg range. In
addition to the instability, forecast soundings have a capping
inversion in the 850 and 700 mb layer. In the early evening,
large-scale ascent will move across the central Plains, helping to
weaken the cap for a few hours. If convective initiation can take
place, an isolated severe storm would be possible. 0-6 km shear in
the 30 to 40 knot range along with steep mid-level lapse rates could
be enough for hail and isolated severe wind gusts.
..Broyles.. 05/12/2026
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Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0357 AM CDT Tue May 12 2026
Valid 151200Z - 201200Z
...DISCUSSION...
...Friday/Day 4 to Sunday/Day 6...
Over the weekend, mid-level flow is forecast to gradually become
southwesterly across the central U.S. In response, low-level
moisture advection will occur in the Great Plains. By Friday
afternoon, a moist and unstable airmass is forecast to be in place
from north Texas into Oklahoma, eastern Kansas and central to
northern Missouri. Isolated severe storms will be possible within
this airmass Friday afternoon and evening.
On Saturday, a dryline is forecast to develop from the far eastern
Texas Panhandle northward into west-central Kansas. To the east of
the dryline, surface dewpoints in the 60s F will contribute to
moderate instability by afternoon. As a mid-level shortwave trough
approaches in the afternoon, scattered thunderstorms are expected to
form to the east of the dryline from western Oklahoma into central
and eastern Kansas. Supercells with large hail, severe wind gusts,
and a tornado threat could develop.
A surge of deeper low-level moisture is expected across the southern
and central Plains on Sunday, as an upper-level trough moves through
the western U.S. In response, a north-to-south corridor of strong
instability is forecast by afternoon from western Oklahoma north and
northeastward into central and eastern Kansas. Scattered
thunderstorms are expected within this unstable airmass during the
afternoon and evening. MCS development may occur in the evening as a
complex moves northeastward from the central Plains into the mid
Missouri Valley. Supercells with large hail, severe wind gusts and a
tornado threat will be possible.
...Monday/Day 7 and Tuesday/Day 8...
An upper-level trough is forecast to move across the north-central
U.S. on Monday, as a cold front advances southeastward into the mid
Mississippi Valley, Ozarks and southern Plains. Scattered to
numerous thunderstorms are forecast to form ahead of the front in
the afternoon. At this time, model forecasts suggest that
instability and deep-layer shear will be strong enough for severe
storms across a broad area. However, uncertainty exists concerning
the location of the front Monday afternoon. A severe threat area may
be needed in later Outlooks, once confidence increases concerning
the timing of the front.
On Tuesday, the cold front is forecast to move southward into north
Texas and the southern Ozarks. An isolated severe threat could
develop ahead of the front in the afternoon and evening. However,
uncertainty is substantial at this extended range.
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