RSS Mesoscale Discussions from Storm Prediction Center
No watches are valid as of Tue May 12 07:02:02 UTC 2026.
No Mesoscale Discussions are in effect as of Tue May 12 07:02:02 UTC 2026.
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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SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0129 AM CDT Tue May 12 2026
Valid 121200Z - 131200Z
...Synopsis...
An upper level low will approach the northwestern U.S. coastline as
troughing and an associated mid-level low traverse the Upper Midwest
and Great Lakes region. Between surface high pressure centered over
southern MT and an eastward propagating surface low towards the
Great Lakes, tightened pressure gradients will encourage strong
deep-layer northwesterly flow to overspread a well-mixed
post-frontal airmass across the mid-upper Missouri Valley.
While RH reductions will be modest in the post-frontal airmass
(around 20-30 percent), 15-25 mph sustained northwesterly winds
(localized gusts up to 35 mph) amid very dry fuels will support
Elevated fire-weather conditions. A swath of stronger sustained
northwest winds between 20-30 mph (localized gusts up to 45 mph)
will impact the eastern Dakotas into the mid-upper Missouri Valley.
However, this corridor of stronger winds will be displaced to the
east of a warmer, drier boundary layer and atop fuels recently
transitioning to green up. While RH values are expected to remain
above 25 percent within this region, locally critical fire weather
conditions may emerge in areas of stronger winds and lower RH.
..Elizalde-Garcia.. 05/12/2026
...Please see www.spc.noaa.gov/fire for graphic product...
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SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0132 AM CDT Tue May 12 2026
Valid 131200Z - 141200Z
...CRITICAL FIRE WEATHER AREA FOR NORTHEASTERN MONTANA INTO FAR
NORTHWESTERN NORTH DAKOTA...
...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.
..Elizalde-Garcia.. 05/12/2026
...Please see www.spc.noaa.gov/fire for graphic product...
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