RSS Mesoscale Discussions from Storm Prediction Center
No watches are valid as of Tue May 12 22:15:02 UTC 2026.
MD 0709 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR EASTERN WISCONSIN...SOUTHWEST UPPER MICHIGAN...AND NORTHWEST LOWER MICHIGAN
Mesoscale Discussion 0709
NWS Storm Prediction Center Norman OK
0436 PM CDT Tue May 12 2026
Areas affected...Eastern Wisconsin...southwest upper Michigan...and
northwest lower Michigan
Concerning...Severe potential...Watch unlikely
Valid 122136Z - 122330Z
Probability of Watch Issuance...5 percent
SUMMARY...Isolated occurrences of locally strong wind gusts and/or
sub-severe hail are possible with the strongest storms late this
afternoon into early evening. A Severe Thunderstorm Watch is not
anticipated.
DISCUSSION...Recent trends in radar and lightning data indicate a
gradual deepening of convection into thunderstorms across parts of
northeast WI, southwest through north of Green Bay, as of 21:30z.
The developing thunderstorms are occurring in close proximity to an
eastward-moving surface low that is being driven by a potent
short-wave trough moving into the upper Great Lakes. The air mass
ahead of the low and trailing cold front has warmed in to the low to
mid 70s at some locations, which coupled with dewpoints in the 40s
and steep low/mid-level lapse rates is resulting in a pocket of
MUCAPE of up to 500 J/kg.
The current KGRB VWP is sampling 40-50 kt westerly winds in the
2-4-km layer, which could potentially be transferred to the ground
by any stronger downdrafts, resulting in similar surface wind gusts.
Some hail is also possible, given the steep lapse rates and cold
mid-level temperatures. The meager instability is expected to limit
overall hail size, with the majority of hailstones remaining below
1".
Latest short-term guidance suggest that the evolving storms will
spread east across far southwest upper MI and Lake Michigan into
northwest lower MI by 00z. At that time, forecast soundings suggest
that storms will likely be elevated atop a stable near-surface
layer, with the potential for sub-severe hail to continue.
Given the expected marginally of severe-weather potential, a watch
is not expected.
..Mead/Gleason.. 05/12/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...APX...GRR...MQT...GRB...MKX...
LAT...LON 44308913 44998893 45588852 45858738 45678538 45208484
44458504 43888533 43708588 43698700 43708781 43728835
43858889 44308913
MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN
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SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0254 PM CDT Tue May 12 2026
Valid 122000Z - 131200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE GREAT LAKES...CENTRAL PLAINS AND FLORIDA...
...SUMMARY...
Severe storms remain possible across parts of the Florida Peninsula
today, and potentially from southeast Kansas into parts of the Great
Lakes late this afternoon and early evening.
...20z Update Great Lakes...
Afternoon visible imagery shows the cold core of an upper-level
trough beginning to impinging on modest low-level moisture south of
a stalled front near the MI/WI border. While moisture and resulting
buoyancy remain very limited (200-300 J/kg MUCAPE), steep mid-level
lapse rates and continued heating should support enough
destabilization for a few storms this afternoon and evening. Hail is
possible, especially with any storms elevated above the surface
given fairly strong mid-level flow. Have adjusted 5% hail
probabilities northward toward the warm front across the MI/WI
border.
...FL...
Numerous storms are ongoing this afternoon south of an east-west
oriented baroclinic zone across the FL Peninsula. To the south, the
environment remains moderately unstable and sheared, which has
supported a few organized clusters and supercells so far. Hail,
damaging winds, and a brief tornado remain possible with the
strongest storms as the boundary is forecast to sag southward
through tonight. Have removed severe probabilities and trimmed
thunder behind the boundary where the air mass has stabilized.
Otherwise, the prior outlooks remains valid with only minor
adjustments. See the previous discussion for more information.
..Lyons.. 05/12/2026
.PREV DISCUSSION... /ISSUED 1127 AM CDT Tue May 12 2026/
...Florida...
A very moist airmass is in place across the FL Peninsula today, with
surface observations showing dewpoints in the low to mid 70s.
Mesoanalysis estimates MLCAPE is at or above 1500 J/kg for much of
the peninsula already. A shortwave trough is currently moving into
the central Gulf Coast vicinity, with continued
eastward/southeastward progress expected throughout the day. The
prevailing buoyancy coupled with ascent attendant to this wave will
result in scattered to numerous thunderstorms. Low-level flow is
generally weak, but the shift from low-level easterly winds to
moderate southwesterly aloft is supporting moderate deep-layer
vertical shear. Some increased shear is possible in the vicinity of
the east-coast sea-breeze, with the strongest storms anticipated
near this boundary as a result. The overall expectation is for some
organized multicells and a few supercells, posing a risk of damaging
wind gusts and hail, particularly across the east-central portions
of the peninsula.
...Upper Midwest through the Mid MO Valley into southeast
KS/northeast OK...
Recent satellite imagery shows a well-defined shortwave trough
moving through the Upper Midwest towards the Upper Great Lakes.
Surface analysis places the low associated with this shortwave over
the northern MN/WI border vicinity, with an attendant cold front
extending back southwestward through northwest IA,
southeast/south-central NE, and far northwest KS. A modest
pre-frontal trough is in place just ahead of this cold front. The
shortwave trough is forecast to continue eastward, while the cold
front progresses eastward/southeastward. Northern portion of this
front (closer to the surface low and parent shortwave) will make
notably more eastward/southeastward progress than the
southern/western portion, which will move more gradually
southeastward.
Low-level moisture advection is anticipated ahead of the front, but
with mid 50s dewpoints currently in central OK, the extent and
quality of this moisture will likely be somewhat limited. Filtered
heating and mixing could also reduce dewpoints. Even so, dewpoints
will likely still reach at least the mid 40s across southern WI,
gradually increasing into the mid 50s across southeast KS/southwest
MO/northeast OK. This is expected to be enough moisture to support a
narrow corridor of modest buoyancy. Strongest ascent will be near
the surface low and shortwave trough across the Upper/Mid MS Valley,
supporting higher storm coverage than areas farther southwest. A few
high-based storms capable of wind damage and isolated hail are
possible.
Farther southwest, lower storm coverage is expected, particularly
from west-central IL into southeast KS. Thunderstorm chances across
much of this area appear low enough to remove severe probabilities.
The only exception is over the southeast KS/southwest MO vicinity.
Here, greater low to mid-level moisture could still support a storm
or two. Shear is strong enough to support hail with any storms that
mature.
Read more
SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1233 PM CDT Tue May 12 2026
Valid 131200Z - 141200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR NORTH-CENTRAL
MONTANA...
...SUMMARY...
Scattered severe thunderstorms are possible across portions of the
northern High Plains Wednesday afternoon and evening. Severe wind
gusts are the primary hazard.
...Northern Rockies and High Plains into northern Utah...
A potent mid-level shortwave trough over western OR/WA will move
east across the northern Rockies into the northern High Plains as a
downstream ridge shifts east into the Upper Midwest by early
Thursday morning. An attendant 80-90 kt 500 mb speed max will
overspread ID/MT by peak heating as a cold front sweeps east across
portions of the northern Rockies into the northern parts of the
Great Basin. Forcing for ascent and diurnal destabilization will
lead to scattered thunderstorms developing by mid afternoon.
Forecast soundings show large surface temperature-dewpoint
depressions and inverted-V thermodynamic profiles. Increasing flow
through the cloud-bearing layer will result in relatively swift
storm motions within pre-conditioned, dry-adiabatic 0-3 km lapse
rates. Isolated to scattered storms developing over the higher
terrain will move into the lower elevations and increase in coverage
as a couple of linear clusters evolve towards early evening across
central MT, and to a lesser degree, across eastern ID. The primary
risk will be severe gusts (60-80 mph) accompanying the stronger
cores and outflow. Farther south, very deeply mixed boundary layers
evident in forecast soundings across northern UT into southern ID
will favor severe gusts with the stronger cores.
...Ohio Valley/Central Appalachians...
An upper-level trough initially over the central Great Lakes will
move east-southeastward to the Lower Great Lakes and Mid-Atlantic
states vicinity during the period. Strong cyclonically curved,
500-mb flow (50+ kt) will move through the base of the trough. A
surface 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
steepen by midday/early afternoon, lending the potential for several
stronger thunderstorms capable of an isolated risk for wind damage
and localized severe gusts.
...TX Panhandle...
Despite a 500-mb ridge overhead, very strong boundary layer heating
may sufficiently erode convective inhibition and yield a couple of
thunderstorms developing near the Caprock (22-00 UTC). Very steep
lapse rates will support an isolated risk for hail/wind if sustained
storms develop. This activity will likely dissipate by mid evening.
..Smith.. 05/12/2026
Read more
SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0229 PM CDT Tue May 12 2026
Valid 141200Z - 151200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
CENTRAL AND EASTERN KANSAS...
...SUMMARY...
Widely scattered severe thunderstorms are possible on Thursday over
the central Great Plains. Large to very large hail and severe gusts
will likely be the primary severe hazards.
...Central Great Plains into the lower MO Valley...
Weak elevated showers/storms will likely be ongoing over eastern KS
Thursday morning owing to warm advection as low-level southerly flow
strengthens. A mid-level disturbance is forecast to move from the
CO Front Range to the mid MS Valley during the period invoking
poleward moisture transport via southerly flow. Model guidance
suggests surface dewpoints to rise into the 60s deg F in an narrow
tongue along and east of I-35 in OK and I-135 in central KS. An
elevated mixed layer featuring steep 700-500 mb lapse rates (in
excess of 8 deg C/km) will contribute towards maintaining a cap
through mid afternoon as a moderately to locally very unstable
airmass develops east of a dryline. Strong heating and large-scale
ascent associated with the eastward-migrating impulse will act to
erode convective inhibition. Isolated to widely scattered storms
are possible during the 21-00 UTC period. Forecast soundings favor
supercells with mainly a risk for large to very large hail. Severe
gusts are also possible and would likely focus if small clustering
can occur during the early evening as this activity moves east
towards the lower MO Valley. A south-southwesterly LLJ is forecast
to slightly veer and favor strengthening warm-air advection Thursday
night into the lower MO Valley, perhaps facilitating a lingering
risk for wind/hail and/or additional elevated thunderstorms posing
an overnight hail threat.
..Smith.. 05/12/2026
Read more
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0302 PM CDT Tue May 12 2026
Valid 131200Z - 141200Z
...CRITICAL FIRE WEATHER AREA FOR NORTHEASTERN MONTANA INTO FAR
NORTHWESTERN NORTH DAKOTA...
...Northern Montana...
A robust upper-level short wave trough and associated increased
southwest flow aloft will enter the Pacific Northwest and Northern
Rockies Wednesday, bringing widespread fire weather concerns to much
of the Intermountain West. A deepening surface trough across the
southern Canadian Prairies into central MT will usher in stronger
southerly to southeasterly winds of 15-25 mph ahead of the trough.
These winds, along with RH as low as 20-30% amid dry fuels will
promote heightened fire weather threat in portions of the central
and northern Plains. Alignment of RH of 20% or below and winds of
around 25 mph is most likely across northeastern MT and far western
ND where fuels are more receptive.
Increasing mid-level moisture ahead of the upper trough and arrival
of a Pacific cold front should promote isolated to scattered showers
and initially high-based thunderstorms across much of northwestern
MT Wednesday. Latest forecast guidance suggests higher rain amounts
(greater than 0.10") across portions of north central MT. Thus,
isolated dry thunderstorm highlights were trimmed across
north-central MT and shifted slightly southeastward, where fast
northeastward storm motions of 35-45 mph and less thunderstorm
coverage will limit potential for wetting rains.
...Southwest, Upper Snake River Plain and Colorado River Basin...
An expansive fire weather threat remains across much of the
Intermountain West as the upper-level trough and attendant
increasing southwest winds aloft shifts into the Pacific North
west. Dry and breezy southwesterly flow of 15-25 mph (localized 30
mph in the eastern Great Basin) and RH of 10-15% will align with
drying fuels to promote elevated fire weather conditions across
portions of the Great Basin, CO River Basin into central WY.
Forecast thermodynamic profiles (with a prominent dry boundary
layer) will support isolated high-based showers and thunderstorms
over higher terrain of western NM, far eastern AZ, central UT
mountain chain into southwest WY.
..Williams.. 05/12/2026
.PREV DISCUSSION... /ISSUED 0132 AM CDT Tue May 12 2026/
...Synopsis...
An upper level low will move onshore the Pacific Northwest and
transform into an open trough as it moves farther inland. Wedged
between western U.S. troughing and an amplifying longwave trough
over the eastern U.S., upper ridging will slide over the Rocky
Mountain region. Associated with the substantial mid-upper level
pattern, a rapidly evolving lee-side low in the southern Canadian
Prairies and deepening lee surface troughing over the Great Basin
and High Plains will present a multifaceted fire weather setup
across portions of the Intermountain West.
...Northern Montana...
In the southern Canadian Prairies, a rapidly evolving lee low will
promote a dry return flow pattern across the northern High Plains. A
Critical fire weather risk was introduced for northeastern MT and
far northwestern ND where sustained southeasterly winds of 20-25 mph
and 15-20 percent RH will overlap an exceptionally dry fuelscape.
Widespread south-southeasterly winds of 15-20 mph amid 20-25 percent
RH will promote elevated fire weather concerns across much of
central-eastern MT. Fast moving, high based showers and
thunderstorms with limited precipitation are expected across central
and northern MT as broader ascent materializes ahead of an incoming
trough. Resultant instability and a dry boundary layer could
encourage a few lightning ignitions where receptive fuels exist. An
IsoDryT area was introduced to account for this threat.
...Portions of the Southwest into the Snake River Plain and Colorado
River Basin...
As the sharp upper trough and associated mid-level jet shifts over
ID into western MT, deepening surface troughing across the northern
Great Basin and stronger southwesterly flow ahead of the trough will
bring fire weather concerns to much of the Intermountain West.
Southwest winds of 15-25 mph amid very low RH and drying fuels under
successive days of abnormally high temperatures will support an
Elevated fire weather threat across the region. Daytime instability
and increasing mid-level moisture will promote high based convection
along the higher terrain of the Four Corners through central WY into
the Wyoming Basin. Sporadic lightning ignitions are possible where
drier fuels exist, promoting an IsoDryT area.
...Please see www.spc.noaa.gov/fire for graphic product...
Read more
SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0509 PM CDT Tue May 12 2026
Valid 141200Z - 201200Z
...Synopsis...
An upper-level trough ejects into the northern Plains on Day
3/Thursday while a surface low shifts into Manitoba. At the surface,
a strong, dry cold front extending south of the low sweeps into the
Upper Midwest bringing widespread fire weather concerns to portions
of the northern Plains and central High plains. Breezy west winds
and dry conditions should linger over portions of the northern
Plains and Upper Midwest on Day 4/Friday as the surface low
translates eastward into Ontario. A large scale upper trough enters
the western U.S. by the end of the weekend bringing a fire weather
threat, including breezy southwest winds and very dry conditions, to
portions of the Great Basin and Four Corners regions on Day
5/Saturday, shifting into the Southwest by Day 6/Sunday.
...Day 3/Thursday...
...Northern Plains...
Strong, deep layer westerly winds behind a powerful cold front under
a similarly robust mid-level jet will bring a fire weather threat to
much of Northern Plains on Day 3/Thursday. West winds of 35-45 mph
are possible with higher gusts across the Plains of MT and terrain
favored areas in central and eastern WY. A mixed fuels picture
across the region, including green up across southeastern MT and ND,
could somewhat mitigate the fire environment precluding introduction
of 70% critical probabilities within the expanded 40% area.
...Southwest and Southern High Plains...
Surface lee troughing over the TX Panhandle under modest westerly
flow aloft will promote enhanced southwesterly winds from southern
NM into the OK/TX Panhandles Day 3/Thursday. A subtle embedded short
wave feature shifting into Southern Plains could aid in high-based
thunderstorm development across portions of the OK/TX Panhandles,
with deeper boundary layer moisture shunted to the east. A 10% dry
thunderstorm probability was introduced.
...Day 4/Friday - Northern Plains...
Dry, post-frontal westerly flow will continue to bring fire weather
concerns to portions of the Northern Plains on Day 4/Friday. Fuels
remain largely receptive although notable green up in some areas may
suppress wildfire spread potential.
Day 5-6/Saturday-Sunday - Great Basin, Four Corners and Southwest...
A larger scale trough impinges upon the western CONUS by the
weekend, reintroducing dry conditions and breezy southwest winds
into the Great Basin and Four Corners regions by Day 5/Saturday. As
the trough migrates eastward, the fire weather threat shifts into
the Southwest on Day 6/Sunday, where several days of drying could
support a more receptive fuelscape for wildfire spread.
..Williams.. 05/12/2026
...Please see www.spc.noaa.gov/fire for graphic product...
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