RSS Mesoscale Discussions from Storm Prediction Center
Public Severe Weather Outlook
PUBLIC SEVERE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0750 AM CDT MON MAY 18 2026
...Severe thunderstorms expected over parts of the south-central
Plains and mid Missouri Valley this afternoon and evening...
* LOCATIONS...
Iowa
Central and Eastern Kansas
Northwest Missouri
Southeast Nebraska
Northern Oklahoma
* HAZARDS...
Several tornadoes, a couple intense
Scattered damaging winds, some hurricane force
Widespread baseball-size hail
* SUMMARY...
Numerous severe thunderstorms are expected this afternoon and
evening across the south-central Plains and mid Missouri Valley.
Supercells capable of producing very large to giant hail and
multiple strong to intense tornadoes are most likely from
central Kansas and southeast Nebraska into Iowa and northwest
Missouri.
Preparedness actions...
Review your severe weather safety procedures for the possibility
of dangerous weather today. Stay tuned to NOAA Weather Radio,
weather.gov, or other media for watches and warnings. A tornado
watch means that conditions are favorable for tornadoes to form
during the next several hours. If a tornado warning is issued for
your area, move to a place of safety, ideally in a basement or
interior room on the lowest floor of a sturdy building.
Read more
SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0744 AM CDT Mon May 18 2026
Valid 181300Z - 191200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
CENTRAL/NORTHEAST KANSAS...SOUTHEAST NEBRASKA...AND FAR NORTHWEST
MISSOURI...
...SUMMARY...
Numerous severe thunderstorms are expected this afternoon and
evening across the south-central Plains and mid Missouri Valley.
Supercells capable of producing very large to giant hail and
multiple strong to intense tornadoes are most likely from central
Kansas and southeast Nebraska into Iowa and northwest Missouri.
...Central Plains into the Midwest/Great Lakes...
Extensive convection continues this morning from western IL into MO
and far eastern KS, aided by warm/moist advection associated with a
40-50 kt southwesterly low-level jet. Gradual destabilization of the
airmass downstream of this ongoing activity is expected today across
the mid MS Valley and Midwest/OH Valley/Great Lakes. Some potential
exists for re-intensification of one or more bowing clusters, with
scattered damaging winds the main concern as low-level lapse rates
gradually steepen. Somewhat less instability and more modest
mid-level flow and related deep-layer shear with eastward extent
into the OH Valley should induce gradual weakening with these
clusters this evening.
The outflow boundary from the morning convection across KS will
likely play a key role in determining the northern extent of
appreciable severe risk later today across the central Plains into
the mid MO Valley. There is concern that this boundary's continued
southward movement this morning and ongoing convection to its north
may hinder/delay destabilization this afternoon ahead of the surface
cold front/dryline. Still, strengthening mid-level flow and
large-scale ascent associated with an ejecting shortwave trough is
expected to overspread the developing warm sector across central KS
into southeast NE by mid to late afternoon.
Even with potential limiting factors such as outflow boundary
placement and residual cloud cover, the presence of very steep lapse
rates aloft (reference 12Z DDC observed sounding) and daytime
heating of a rather moist low-level airmass will likely support
strong to possibly extreme instability south of the cold front and
east of the dryline by early afternoon. Most guidance continues to
suggest that robust thunderstorm initiation will occur by 18-22Z
across central/northeast KS into far southeast NE. These initial
supercells should pose a threat for very large to potentially giant
hail (2-4+ inches in diameter). As low-level shear gradually
increases through late afternoon/early evening in tandem with a
strengthening southerly low-level jet, a focused spatial/temporal
corridor for strong to intense tornadoes should exist across parts
of central/northeast KS into far southeast NE and northwest MO.
Fairly quick upscale growth appears likely by mid to late evening as
thunderstorm mergers/interactions occur, and as the cold front
advances east-southeastward. Even so, a continued threat for QLCS
and embedded supercell tornadoes should continue, as low-level shear
will remain enhanced by a 50+ kt low-level jet. Severe/damaging
winds will also become an increasing concern as convection spreads
eastward in tandem with the cold front. Some severe wind threat may
persist through much of the night since ample instability is
forecast to exist ahead of convection, especially across KS/MO/OK.
...Southern Plains...
Thunderstorm initiation along the dryline this afternoon/early
evening across western OK into western north TX is more uncertain
than locations farther north given expectations for more limited
forcing for ascent. If/where convection does form, there is the
potential for very large hail and a conditional risk for tornadoes
with any persistent supercells, given the presence of steep
mid-level lapse rates, strong instability, moderate deep-layer
shear, and gradually increasing low-level shear this evening. But,
weaker winds above 400 mb by late afternoon/evening may not be
overly favorable for long-lived convection, even if it does form.
...Mid-Atlantic/Northeast...
Influenced by terrain and a surface trough, isolated strong to
severe thunderstorms capable of producing occasional wind damage may
occur this afternoon within a moderately unstable environment.
..Gleason/Marsh.. 05/18/2026
Read more
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1125 AM CDT Mon May 18 2026
Valid 181630Z - 191200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND EVENING OVER PARTS OF EASTERN KANSAS...SOUTHEAST
NEBRASKA...NORTHWEST MISSOURI...AND SOUTHWEST IOWA....
...SUMMARY...
Numerous severe thunderstorms are expected this afternoon and
evening across the south-central Plains and mid Missouri Valley.
Supercells capable of producing very large to giant hail and
multiple strong to intense tornadoes are most likely from central
Kansas and southeast Nebraska into Iowa and northwest Missouri.
...Central Plains...
Morning water vapor loop shows a potent shortwave trough rotating
across the central Rockies into western KS. The primary surface
boundary extends from western IA into central KS, with a pronounced
outflow boundary associated with overnight convection extending from
southeast KS into southern MO. The outflow boundary will lift
northward today, allowing a very moist and extremely unstable air
mass to spread into eastern KS/northwest MO/extreme southeast
NE/southwest IA. This is the area most concerning for intense
supercells later today.
Initial storms are expected to develop by early afternoon near the
triple point of the retreating outflow boundary and cold front.
These storms will track northeastward through the afternoon and
early evening in a strongly sheared environment favorable for
tornadoes, very large hail, and damaging winds. It remains unclear
how stormscale interactions will impact discrete supercell mode, but
strong tornadoes are a concern in this region.
Farther southwest, thunderstorms will develop in vicinity of the
cold front across south-central KS by late afternoon. Recent CAM
solutions suggest these storms may be affected by the linear frontal
forcing, and may be slightly anafrontal. This would lessen the
tornado risk, but very large hail and damaging winds would remain a
concern. No changes have been made to the Moderate Risk area due to
conflicting model signals.
...Western OK/Northwest TX...
Full sunshine will lead to hot temperatures along the dryline over
western OK into northwest TX. At least isolated thunderstorms are
expected to form in this area, with a risk of large hail and
damaging winds. Weak large scale forcing may limit storm duration
and intensity.
...OH Valley/Great Lakes...
A line of thunderstorms along the IL/IN border is tracking
northeastward into a warm/moist air mass. Relatively strong
low-level wind fields and steep low-level lapse rates suggest a
continued risk of scattered wind damage with the strongest storms as
they track across parts of IN/Lower MI/Northwest OH.
..Hart/Halbert.. 05/18/2026
Read more
SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1220 PM CDT Mon May 18 2026
Valid 191200Z - 201200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE GREAT
LAKES INTO SOUTHERN PLAINS...
...SUMMARY...
Widely scattered severe thunderstorms will be possible along a cold
front extending from the Great Lakes into the Ohio Valley and the
southern Plains on Tuesday. Damaging winds and large hail will be
the primary threats.
...Synopsis...
A short-wave trough over the northern Plains into upper MS Valley
Tuesday morning will translate northeast into Ontario with an
associated belt of strong mid-level flow overspreading the Great
Lakes. The stronger mid-level winds will extend southwest into the
central High Plains, downstream from a positively tilted trough
moving through the Great Basin and lower CO Valley.
At the surface, low pressure associated with northern Plains
disturbance will develop from the upper Great Lakes through
southeast Ontario into Quebec. Meanwhile, a trailing cold front will
move through the Great Lakes and OH Valley, with the trailing
extension of the boundary advancing through the mid MS Valley and
southern Plains. The cold front and any preceding outflow boundaries
associated with early-day convection will serve as the main foci for
diurnally enhanced strong to severe storm development.
...Ohio Valley into the Great Lakes and New England...
A southwesterly low-level jet will sustain a moist boundary layer
across the pre-frontal warm sector with dewpoints in the 60s to
perhaps low 70s in the OH Valley. The moisture will combine with
daytime heating to support MLCAPE ranging from 1000-1500 J/kg across
the mid/lower Great Lakes into New England, with as high as
2000-3000 J/kg forecast in the OH Valley. A broad zone of low-level
warm advection coupled with the glancing influence of the Ontario
short-wave trough are expected to support a gradual increase in
thunderstorm coverage and intensity through the afternoon along and
ahead of the synoptic cold front.
The strongest low/mid-level flow and resultant deep-layer shear is
forecast to reside across the Great Lakes and northern New England,
where transient bowing and/or supercell structures appear possible.
Weaker shear with southward extent into the OH Valley will be
supportive of multicell clusters. Damaging wind gusts appear to be
the primary hazard in both regimes, though isolated occurrences of
marginally severe hail are also possible.
...Mid Mississippi Valley into the Southern Plains...
Thunderstorms are expected to be ongoing Tuesday morning along or
ahead of the cold front from the Ozarks into OK. Daytime heating of
the downstream air mass coupled with boundary-layer dewpoints in the
60s to low 70s and steepening mid-level lapse rates with
southwestward extent will support moderate to strong afternoon
instability with MLCAPE of 2000-3000+ J/kg. The 12z models suggest
that a subset of the early-day storms will intensify by afternoon
across the Ozark Plateau with additional thunderstorm development
anticipated along the synoptic cold front and preceding convective
outflow boundaries from the mid MS Valley into the southern Plains.
There is some model signal that one or multiple, weak disturbances
will translate from the southern Plains into Ozark Plateau during
the day, which will aid in the diurnally enhanced storm development.
As alluded to in the synopsis, the strongest mid-level flow and
associated vertical shear is expected remain confined to the
post-frontal air mass. The exception will be across parts of the TX
Permian Basin into the Big Bend and Edwards Plateau, where easterly
low-level winds ahead of front will augment modest mid-level flow to
support 30-40 kt of effective bulk shear. As such, predominant
convective modes will be multicell clusters and line segments
capable of damaging winds and marginally severe hail. Large hail
potential (some hailstones in excess of 2") increases with
southwestward extent into TX owing to steeper mid-level lapse rates
and the potential for supercell storm modes, given the stronger
vertical shear.
..Mead.. 05/18/2026
Read more
Day 4-8 Outlook
Day 4-8 Convective Outlook RESENT 1
NWS Storm Prediction Center Norman OK
0858 AM CDT Mon May 18 2026
Valid 211200Z - 261200Z
...DISCUSSION...
...D4/Thursday - D5/Friday...
On D4/Thursday, a stationary front will extend across the southern
Plains and mid Mississippi Valley and east to the Carolinas.
A few stronger thunderstorms may develop south of this boundary,
however, the strongest upper-level flow will be displaced to the
north, limiting confidence in a more organized severe threat.
Moist southerly return flow will begin across the southern/central
Plains into the weekend. Modest westerly flow across the dryline on
D5/Friday may support some potential for severe storms. Overall,
forcing for ascent will remain limited and there is low confidence
in including a severe risk area at this time.
...D6/Saturday-D8/Monday...
Through the end of the extended period, height rises are expected
across the central US as a high amplitude ridge settles in from the
west. While moisture will continue to move northward into the
central/northern Plains, generally weak flow and subsidence will
keep severe potential low.
Read more
