RSS Mesoscale Discussions from Storm Prediction Center
Public Severe Weather Outlook
PUBLIC SEVERE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0106 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 very large hail and 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.
&&
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SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1255 AM CDT Mon May 18 2026
Valid 181200Z - 191200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS
EASTERN/SOUTH-CENTRAL KANSAS AND SOUTHEAST NEBRASKA/FAR NORTHWEST
MISSOURI...
...SUMMARY...
Numerous severe thunderstorms are expected this afternoon and
evening across the south-central Plains and Middle Missouri Valley.
Supercells capable of very large hail and strong to intense
tornadoes are most likely from central Kansas and southeast Nebraska
into Iowa and northwest Missouri.
...Central Plains and Midwest...
A regional outbreak of severe storms, potentially including
strong/intense tornadoes (EF2/EF3+), is expected across the central
Plains during the late afternoon and evening, although some
uncertainties persist regarding the upper-end magnitude/spatial
details of the heightened tornado potential. An extensive MCS exists
early in the overnight from eastern/central Iowa southwestward into
northeast/central Kansas, where regenerative/repetitive storms
persist.
This MCS should weaken/lose integrity through the early morning,
although convection may regenerate and intensify again along
composite outflow, eastward across the middle Mississippi Valley and
lower Ohio Valley and potentially parts of the Great Lakes within a
destabilizing air mass this afternoon. Damaging winds should be the
most probable risk, although some tornado and hail potential will
exist as well.
The western fringe of this remnant cold pool will modify early today
with a steady northward flux of low-level moisture, with a very
unstable environment unfolding by mid/late afternoon across
south-central/eastern Kansas into far west/northwest Missouri and
Iowa/far southeast Nebraska. As a shortwave trough/speed max emerges
from the central Rockies, deep convective development is expected
along the initially stalled or slow-moving
northeast/southwest-oriented front across central/northeast Kansas
and southeast Nebraska and western Iowa by late afternoon.
This increasingly rich low-level moisture will reside beneath an
elevated mixed layer characterized by 8-9 C/km mid-level lapse
rates, resulting in MLCAPE 3000-4000 J/kg. Mass response to the
ejecting wave, along with a northeastward-translating 60-70 kt
mid-level jet, and a significantly strengthening low-level jet by
sunset, will yield increasingly favorable wind profiles for intense
supercells capable of very large hail and tornadoes. This may
includes strong and potentially intense tornadoes (EF2/EF3+). That
said, the duration of a semi-discrete storm mode remains a key
question, given the parallel orientation of the stalled front and
the deep-layer shear vectors, and that the front will trend more
southeastward-progressive during the evening. Thus, the
strong/potentially intense tornado threat will peak prior to upscale
growth into line segments along the front, with severe outflow gusts
and embedded circulations becoming the main concerns over time
tonight as storms progress east-southeastward across the Lower
Missouri Valley and middle Mississippi Valley.
...Oklahoma and western North Texas...
Storm development along the dryline across western Oklahoma into
western North Texas/Lower Rolling Plains is more uncertain given
more limited forcing for ascent. If/where storms do form, there is
the potential for very large hail and a conditional risk for
tornadoes. A consistently forecast flow weakness above 400 mb
by late afternoon/evening does not appear favorable for particularly
long-lived storms if they do form.
...Mid-Atlantic/Northeast States...
Influenced by terrain and a surface trough, isolated strong to
locally severe storms capable of wind damage could occur this
afternoon within a moderately unstable environment.
..Guyer/Squitieri.. 05/18/2026
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SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1254 AM CDT Mon May 18 2026
Valid 191200Z - 201200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE GREAT
LAKES TO THE 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 mid-level trough will lift across the Great Lakes Region on
D2/Tuesday with a surface low moving east across southern Ontario
and Quebec. A trailing cold front will be located from the Great
Lakes south into the Ohio and mid Mississippi Valleys into the
Southern Plains. Convection will likely be ongoing across this
boundary at the beginning of the D2/Tuesday period.
...Great Lakes Vicinity to the Lower Ohio Valley...
Some convection may be ongoing across the cold front towards the
beginning of the D2 period, with additional development likely by
the afternoon along the eastward shifting cold front. Enhanced
mid-level flow aloft and weak to moderate instability will support
organized storms with potential for damaging winds and isolated
large hail. Additional afternoon thunderstorm development may extend
into the Northeast with potential for large hail and damaging wind.
...Mid Mississippi Valley to Southern Plains...
Convection will be ongoing at the start of the period from the mid
Mississippi Valley driven by the cold front and potential cold pool
propagation. These boundaries will be the focus of
re-intensification of convection in the afternoon. Mid-level flow
aloft will be weaker across the region but sufficient shear for
organization should remain in place. A plume of more favorable
moderate to strong instability will be available across
central/northern Texas into southern Oklahoma. With afternoon
development, steep low to mid level lapse rates and moderate
instability will support potential for a few large hail reports.
With time, upscale growth will support a downstream damaging wind
risk.
..Thornton.. 05/18/2026
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SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0224 AM CDT Mon May 18 2026
Valid 201200Z - 211200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE MID ATLANTIC AND SOUTHERN HIGH PLAINS...
...SUMMARY...
Scattered thunderstorm activity across the Mid-Atlantic region
Wednesday may pose a risk for wind and hail. Isolated thunderstorms
within the upslope regime in western Texas/eastern New Mexico will
also pose a risk for large hail.
...Discussion...
The mid-level trough across the Great Lakes will continue to lift
northward into Canada D3/Wednesday. A cold front will extend from
the Northeast southward across the southern Ohio Valley into the
lower Mississippi Valley and westward into southwestern Texas. Near
the front across the Mid-Atlantic, sufficient deep layer shear and
MLCAPE will be in place to support a few organized storms, with
potential for damaging winds and large hail which supports inclusion
of a Marginal Risk.
Further south across western Texas, isolated to scattered afternoon
thunderstorms may develop south of the front within the upslope flow
regime across western Texas into eastern New Mexico. Though deep
layer shear will be generally weak, moderate instability and steep
low to mid-level lapse rates may support a few instances of large
hail and severe winds.
..Thornton.. 05/18/2026
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