RSS Mesoscale Discussions from Storm Prediction Center
WW 213 TORNADO IA MN NE SD 171840Z - 180300Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 213
NWS Storm Prediction Center Norman OK
140 PM CDT Sun May 17 2026
The NWS Storm Prediction Center has issued a
* Tornado Watch for portions of
Northwest Iowa
Far Southwest Minnesota
Northeast Nebraska
Southeast South Dakota
* Effective this Sunday afternoon and evening from 140 PM until
1000 PM CDT.
* Primary threats include...
A few tornadoes likely with a couple intense tornadoes possible
Scattered damaging winds likely with isolated significant gusts
to 85 mph possible
Scattered large hail likely with isolated very large hail events
to 3 inches in diameter possible
SUMMARY...Thunderstorm coverage and intensity is expected to
increase this afternoon along and ahead of a cold front moving into
the Mid Missouri Valley. Strong buoyancy and shear will favor
supercells with any discrete development. These intense supercells
would be capable of all hazards, including very large hail (up to
3"+ in diameter) and strong tornadoes. More linear development is
expected along the front, with strong gusts and line-embedded
possible, particularly across eastern portions of the watch (i.e.
far northeast Nebraska, far southeast South Dakota, northwest Iowa
and southwest Minnesota).
The tornado watch area is approximately along and 70 statute miles
north and south of a line from 40 miles west northwest of Oneill NE
to 35 miles north of Storm Lake IA. For a complete depiction of the
watch see the associated watch outline update (WOUS64 KWNS WOU3).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Tornado Watch means conditions are favorable for
tornadoes and severe thunderstorms in and close to the watch
area. Persons in these areas should be on the lookout for
threatening weather conditions and listen for later statements
and possible warnings.
&&
AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 3 inches. Extreme turbulence and surface wind
gusts to 75 knots. A few cumulonimbi with maximum tops to 500. Mean
storm motion vector 24035.
...Mosier
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WW 0213 Status Updates
STATUS FOR WATCH 0213 HAS NOT BEEN ISSUED YET
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MD 0750 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF THE FLORIDA PENINSULA INTO NORTH FLORIDA AND CENTRAL GEORGIA
Mesoscale Discussion 0750
NWS Storm Prediction Center Norman OK
0142 PM CDT Sun May 17 2026
Areas affected...portions of the Florida Peninsula into North
Florida and central Georgia
Concerning...Severe potential...Watch unlikely
Valid 171842Z - 172045Z
Probability of Watch Issuance...5 percent
SUMMARY...Widely scattered thunderstorms will pose a risk for
isolated damaging wind gusts/downbursts and small to marginally
severe hail through this evening. Watch issuance is not expected.
DISCUSSION...An increase in convective coverage is expected through
this afternoon from the western Florida Peninsula into southern
Georgia along the Atlantic and Gulf Coast sea breezes. Temperatures
in the low-90s F and dewpoints in the upper-60s to low-70s are
supporting moderate to strong buoyancy, with MLCAPE of 2000-3000+
J/kg analyzed per latest mesoanalysis. Despite moderately strong
northwesterly upper-level flow, meager mid-level flow (less than 15
kts sampled at 500 mb by the 12z TBW/JAX observed soundings) is
forecast to limit effective bulk shear to around 20 kts or less.
While this is expected to largely limit storm organization, a
favorable thermodynamic environment should support pulse-severe type
convection. Steep low-level lapse rates (8+ C/km) and PWAT values of
1.5-1.8+ inches will promote the potential for strong to isolated
damaging downburst winds (likely in the 45-55 mph range). Small to
marginally severe hail may also accompany the strongest convective
cores. Convection will largely be diurnally driven, with coverage
forecast to decrease later this evening owing to nocturnal
cooling/stabilization. Given the expectation for storm organization
and threat magnitude to remain limited, watch issuance is not
expected.
..Chalmers/Mosier.. 05/17/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MFL...MLB...TBW...JAX...FFC...TAE...
LAT...LON 27988296 28448283 28868292 29168312 29558337 30138375
30668391 31198400 31858406 32218392 32568369 32678330
32658319 32548275 32168234 31808217 31478196 31118185
30428179 29768173 29118160 28458146 27558119 26888093
26408085 26118095 25988115 25868145 25898175 26248202
27018253 27458277 27988296
MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN
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MD 0749 CONCERNING SEVERE POTENTIAL...TORNADO WATCH LIKELY FOR SOUTHEAST SD...NORTHEAST NE...NORTHWEST IA...AND SOUTHWEST MN
Mesoscale Discussion 0749
NWS Storm Prediction Center Norman OK
0111 PM CDT Sun May 17 2026
Areas affected...southeast SD...northeast NE...northwest IA...and
southwest MN
Concerning...Severe potential...Tornado Watch likely
Valid 171811Z - 172015Z
Probability of Watch Issuance...95 percent
SUMMARY...Severe potential will increase over the next couple of
hours across southeast South Dakota and northeast Nebraska into
adjacent portions of Minnesota and Iowa. A substantial all-hazards
severe risk is expected by mid-afternoon into this evening. Very
large hail to 3.5 inch diameter, strong tornadoes, and intense wind
gusts to 90 mph appear likely. A tornado watch will likely be issued
by 19z to 20z.
DISCUSSION...A cluster of elevated convection is ongoing across
north-central NE ahead of the surface cold front. The downstream
airmass is quickly destabilizing as rich boundary-layer moisture
(mid to upper 60s F dewpoints) spreads north and west amid strong
heating. Immediately downstream from the ongoing thunderstorm
cluster, latest mesoanalysis indicates weakening midlevel capping.
This is supported by increasing cumulus from Brown to Knox and
Antelope Counties in NE in the vicinity of a quasi-stationary
boundary/warm front. Increasing midlevel southwesterly flow is
evident in the past couple of hours on region VWP. This trend should
continue, with additional strengthening of low-level flow in
response to surface pressure falls. Vertically veering wind profiles
with 40+ kt effective shear magnitudes within moderate to strong
instability (by mid/late afternoon) will support robust supercell
development within the warm sector on the nose of the midlevel dry
slot across the northeast NE vicinity. Discrete supercells will pose
a risk for very large hail, strong tornadoes, and damaging wind
gusts.
Additional linear convection is expected along the cold front,
particularly across SD into southern MN. Given favorable low-level
shear, line-embedded cells/mesovortices will pose a tornado risk
even in linear convection. As linear convection organizes and a
low-level jet increases toward late afternoon into the evening, a
substantial damaging wind risk may evolve.
..Leitman/Mosier.. 05/17/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DMX...FSD...OAX...GID...LBF...UNR...
LAT...LON 41509588 41419680 41489786 41779924 42209988 42570005
42989990 43169978 43529913 44229752 44329681 44329625
44229587 43959537 43419522 42589536 41979555 41509588
MOST PROBABLE PEAK TORNADO INTENSITY...120-145 MPH
MOST PROBABLE PEAK WIND GUST...75-90 MPH
MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN
Read more
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1129 AM CDT Sun May 17 2026
Valid 171630Z - 181200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL PLAINS AND MID MISSOURI VALLEY...
...SUMMARY...
Severe thunderstorms are expected this afternoon into tonight across
parts of the southern/central Plains to the Upper Midwest.
Supercells with very large hail and strong tornadoes are possible
initially this afternoon, before one or more bowing clusters leads
to a greater threat for severe/damaging winds this evening.
...Synopsis...
12Z soundings across the central and southern Plains reveal steep
mid-level lapse rates (8.8 deg C per km at OUN, SGF, and TOP) atop
returning low-level moisture (100 mb mean mixing ratios of 15.4 and
13.1 g/kg at OUN and FWD, respectively). An MCV, from overnight
storms across the Plains, is progressing into northern IL/southern
MN. 12Z DVN sounding sampled a corridor of 50 kt at the base of this
MCV.
Morning surface analysis reveals an intricate surface pattern across
the High Plains/Plains, with multiple lows within the lee troughing
that extends from eastern MT through the central High Plains, a pair
of warm fronts, and a residual outflow boundary across NE. The
deepest surface low is over the far southern CO/KS border vicinity,
with a warm front extending east-northeastward, roughly along the 70
deg F isotherm. A dryline also extends southward from this low into
far west TX. Another low is in place farther north over western NE.
Another warm front, this one along a sharp gradient in low-level
moisture, extends northeastward from this low into far southeast SD
before arcing more eastward across far southern MN and continuing
across from southern WI into central Lower MI. The aforementioned
outflow also extends eastward from this low across central NE.
All of these boundaries will likely influence the severe potential
today, combining with an emerging upper trough and moderate to
strong instability, to support an expansive and complex scenario
today.
...Central Plains into the Upper Midwest...
Expectation is for the northern warm front mentioned in the synopsis
to continue northward throughout the day while as cold front sweeps
southeastward across SD and NE. Thunderstorm development is
anticipated as the cold front interacts with the returning low-level
moisture. Moderate to strong buoyancy (i.e. MLCAPE from 2000 to 3000
J/kg) will support robust thunderstorms from southeast SD through
south-central NE, potentially as far south as central KS. This
activity along the front will become linear quickly with damaging
gusts as the primary risk. Some cell-in-line structures could
support large to very large hail, particularity early in the
convective cycle.
Within this larger area of severe wind and hail potential, two areas
appear to have a greater tornado threat. One is from
northeast/east-central NE into far southeast SD. Here, the influence
of a residual outflow boundary could support more discrete
development ahead of the front. Any discrete development in the warm
sector would likely be supercellular and capable of all hazards,
including very large hail (over 2.5") and a strong tornado. The
other area is where the convective line interacts with the warm
front amid a strengthening low-level jet, likely far northern IA/far
southern MN. Here, increased low-level shear coupled with
augmentation from interaction with the front could result in
significant severe gusts as well as lined-embedded QLCS tornadoes.
...Central High Plains...
Thunderstorm development still appears likely across northeastern CO
this afternoon in a low-level upslope flow regime. This activity
will likely become supercellular and capable of producing large to
very large hail given the presence of steep mid-level lapse rates,
strong deep-layer shear, and moderate instability. Just how far
east/northeast (into central NE) thunderstorms remains strong is a
question of timing. Earlier storms could interact with the front as
it moves through NE, potential leading to persistence or
reintensification. However, later timing would take these storms
into central NE behind the cold front. Steep mid-level lapse rates
in place could still support these storms for a few hours, but the
overall intensity will likely gradually decrease.
...Southern WI into Lower MI...
An MCV is current progressing into northern IL/southern MN. Modest
buoyancy and moderate deep-layer shear will support isolated
elevated thunderstorms capable of small hail and locally strong wind
gusts through early afternoon. This MCV is expected to continue
northeastward into Lower MI, potentially interacting with a warm
front moving north across the region this afternoon. 12Z DVN
sounding sampled enhanced mid-level flow with this MCV, which could
result in enough shear to support organized convection along and
near the warm front later this afternoon/evening. Strong multicells
and an isolated supercell or two could occur, with an attendant risk
for damaging winds, hail, and perhaps a tornado.
...South-Central KS into the eastern TX Panhandle and western OK...
Some guidance continues to show at least isolated high-based
convection developing by late afternoon across parts of
north-central KS southward into the eastern TX Panhandle/western OK.
Any thunderstorms which can be sustained would likely be
supercellular and capable of all severe hazards, including large to
very large hail and tornadoes. Increasing low-level shear after 00Z
supports a conditional risk for a strong tornado.
-- No changes to these areas from the earlier 13Z Outlook --
...Southeast...
On the western periphery of a surface high centered over the western
Atlantic, diurnally maximized thunderstorm development should focus
from the southern Appalachians across GA and the interior/western FL
Peninsula. Even though deep-layer shear will remain weak, a
favorable thermodynamic environment with steepened low-level lapse
rates should support strong to pulse-severe type convection capable
of producing isolated wind damage/downbursts and perhaps marginally
severe hail.
...Central and North Texas/ArkLaTex/Lower Mississippi Valley...
A fairly robust cap is expected to remain across the southern extent
of the warm sector today, with minimal/nebulous large-scale ascent
over the southern Plains. Still, some guidance suggests elevated
thunderstorms may develop through peak afternoon heating across
parts of northeast TX into the ArkLaTex/lower MS Valley in
persistent low-level warm advection regime. If this occurs, then
isolated severe hail and damaging winds would be possible given the
strong MUCAPE forecast.
...Mid-Atlantic...
Mid-level ridging should build over the Mid-Atlantic through the
afternoon, which should tend to suppress most convection. However, a
weak mid-level perturbation noted in water vapor imagery this
morning over OH may support isolated convective development this
afternoon across parts of MD/PA and vicinity. The overall
environment does not appear overly favorable for organized severe
thunderstorms, but gusty winds could occur with any of the stronger
cores that may develop.
..Mosier/Chalmers.. 05/17/2026
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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1230 PM CDT Sun May 17 2026
Valid 181200Z - 191200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM CENTRAL
KANSAS TO SOUTHEAST NEBRASKA...
...SUMMARY...
Numerous severe thunderstorms are expected to develop Monday along a
cold front and dryline extending from the Great Lakes into the
central/southern Plains. Supercells capable of very large hail and
strong to intense tornadoes are most likely from central Kansas into
southeast Nebraska.
...Synopsis...
A midlevel shortwave trough, now approaching the northern Great
Basin, will move to near the Four Corners by Monday morning and then
eject northeastward over northwest KS/NE during the afternoon and to
the upper MS Valley by early Tuesday. This path will be along and
just northwest of a stalled baroclinic zone from the central Plains
into the upper MS Valley, such that the primary height falls and
forcing for ascent will brush the northwest side of the surface warm
sector from KS to IA. A remnant lee cyclone will persist through
the afternoon near the southwest KS/OK Panhandle border, prior to a
surge of the cold front in the immediate wake of the midlevel
trough. Downstream from the ejecting trough, surface cyclogenesis
is expected Monday night from IA into WI along a stalled front.
...KS to IA...
There are a few questions surrounding the forecast for Monday
afternoon/night. The northeast extent of the unstable warm sector
will depend on the persistence of rain-cooled air with morning
convection across IA/northern MO/northwest IL. This convection and
an associated MCV could continue eastward through the day across
central/northern IL, northern IN, northwest OH and Lower MI with the
potential for occasional wind damage and isolated large hail. The
west edge of the remnant cold pool should modify by
afternoon/evening from the MO/KS/NE border area into IA, prior to
thunderstorm development along the stalled front (and immediately in
advance of glancing influence of the ejecting midlevel trough)
21-00z from central KS into southeast NE and western IA.
Rich low-level moisture (boundary-layer dewpoints 68-72 F) is
spreading northward now from TX to OK and will be established in the
warm sector Monday. The moisture will reside beneath an elevated
mixed layer with 8-9 C/km midlevel lapse rates and will combine with
daytime heating to drive MLCAPE of 3000-4000 J/kg. Mass response to
the ejecting wave and the typical evening ramp up of a low-level jet
will result in favorable wind profiles/hodographs for supercells
capable of producing strong-intense tornadoes and very large hail.
The duration of a semi-discrete storm mode is another question,
given the parallel orientation of the stalled front and the
deep-layer shear vectors, in combination with focused ascent. Thus,
the strong 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 into Monday night.
...OK/northwest TX...
Storm development along the dryline to the south in OK/northwest TX
is more uncertain given little forcing for ascent. If storms do
form, there will be a conditional threat for tornadoes and very
large hail. A consistent forecast weakness in the flow above 500 mb
by late afternoon/evening does not appear favorable for particularly
long-lived storms if they do form. The more probable scenario
remains a back-building line of storms along the cold front with
occasional hail/wind Monday night.
..Thompson.. 05/17/2026
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SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0211 PM CDT Sun May 17 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.
...Great Lakes and vicinity...
An ejecting midlevel trough over the upper MS Valley early in the
period will begin to phase with the northern stream while moving
eastward over the Great Lakes. An associated surface cyclone will
move across southern ON/QC, as a trailing cold front progresses
southeastward across the OH/middle MS Valleys and into the southern
Plains. Convection will likely be ongoing at the start of the
period along the cold front from northwest TX and OK to the middle
MS Valley and the vicinity of Lake MI. The stronger low-midlevel
flow will be confined to the area closer to the Great Lakes, where
some diurnal destabilization could allow an uptick in threat for
wind damage and isolated large hail.
...Lower OH Valley into the southern Plains...
Farther southwest, flow aloft will be weaker and convection will be
tied to the slowing front and/or convective outflows from D2
convection persisting into D3. Moderate to strong buoyancy (greater
to the west into TX) is expected just ahead of the front, which
combined with the relatively weak wind profiles, will favor
multicell clusters and line segments capable of producing occasional
wind damage and isolated large hail through the afternoon. There
will be some potential for an isolated supercell or two to move off
the Serranias del Burro into TX where large CAPE will coincide with
the cyclonic side of the subtropical jet and at least marginally
sufficient vertical shear. Otherwise, the pattern will transition
overnight to a weak warm advection regime atop the cool air mass,
where elevated storms could produce large hail from northwest TX
into southern OK.
..Thompson.. 05/17/2026
Read more
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1103 AM CDT Sun May 17 2026
Valid 171700Z - 181200Z
...EXTREMELY CRITICAL FIRE WEATHER AREA FOR PORTIONS OF EXTREME
EASTERN NEW MEXICO...EXTREME SOUTHEASTERN COLORADO...SOUTHWESTERN
KANSAS...AND PARTS OF THE TEXAS AND OKLAHOMA PANHANDLES...
...CRITICAL FIRE WEATHER AREA FOR MUCH OF NEW MEXICO INTO THE
SOUTHERN HIGH PLAINS...
...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE SACRAMENTO VALLEY
IN CALIFORNIA...
The overall forecast remains on track today as the threat of
dangerous fire weather continues across the southern High Plains.
Slight adjustments were made to expand the northern extent of the
Extremely Critical area over far northeastern NM, far southeastern
CO, and southwestern KS. The latest forecast guidance indicates that
the placement of the dryline remains as anticipated with the
previous forecast issuance. That being said, the Extremely Critical
conditions are expected to impact areas just behind the dryline, so
the risk gradient was tightened across this area. Farther west, the
existing Elevated area was expanded, over portions of southern UT
and northern AZ, though fuels are comparatively less receptive. Even
so, fire weather risk amid west-southwesterly winds of 15-25 mph
combined with 10-20% minimum RHs over these regions is worth
highlighting. Additionally, expect winds to quickly turn northerly
behind a significant cold front sweeping across the country, which
will arrive over southern UT around sunset this evening.
..Stearns.. 05/17/2026
.PREV DISCUSSION... /ISSUED 0134 AM CDT Sun May 17 2026/
...Synopsis...
***Dangerous fire weather conditions are expected across the
southern High Plains today***
A deepening mid-level trough across the Rockies will support
appreciable surface low intensification across the central Plains
today. The combination of strong downslope flow from the Rockies, in
tandem with gradient westerly flow, will support very dry and windy
conditions across portions of the Southwest into the southern High
Plains. With above average fuel loading of very dry grasses and
holdovers from previous fires already present across the southern
High Plains, the very dry and windy conditions will promote a
volatile setup for rapid, dangerous wildfire spread potential.
...Southern High Plains...
A dryline will sharpen along the Texas Panhandle/western Oklahoma
border during the afternoon, with a very dry boundary layer expected
to mix up to at least 600 mb behind the dryline, from central New
Mexico into the Texas Panhandle and southwestern Kansas areas. While
gradient westerly surface flow will increase through the day,
downward mixing of stronger flow aloft in the post-dryline
environment will support widespread 25-30 mph sustained
west-southwesterly surface winds amid 5-15 percent RH. These
conditions are likely across much of New Mexico to the immediate
dryline vicinity, where Critical highlights have been maintained.
Extremely Critical highlights have been adjusted to where guidance
consensus shows the longest term overlap of the aforementioned
winds/RH with loaded fuels exceeding the 95th percentile. While the
sustained surface winds may fall just shy of typical Extremely
Critical criteria, the combination of fuel loading and potential
pre-existing holdovers of earlier fire starts suggests that a
volatile landscape will be in place to support dangerous
wildfire-spread potential.
...California Central Valley Region...
Deep-layer north-northwesterly flow will overspread the Central
Valley region as a mid-level jet streak overspreads California on
the backside of an upper trough. Downslope flow from the higher
terrain will support surface winds exceeding 25 mph in spots as RH
dips to the 15-20 percent range. Given dry fuels, Critical
highlights have been introduced to the Sacramento Valley region.
Broader Elevated highlights extend into the San Joaquin Valley,
where 15+ mph sustained northerly winds will overlap with 15-20
percent RH.
...Please see www.spc.noaa.gov/fire for graphic product...
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