RSS Mesoscale Discussions from Storm Prediction Center
No watches are valid as of Mon May 11 22:32:02 UTC 2026.
No Mesoscale Discussions are in effect as of Mon May 11 22:32:02 UTC 2026.
SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0246 PM CDT Mon May 11 2026
Valid 112000Z - 121200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE LOWER MISSISSIPPI VALLEY...THE FLORIDA ATLANTIC COAST...AND
THE CAROLINA COAST...
...SUMMARY...
Isolated severe storms with locally damaging wind gusts and hail are
possible this afternoon along the Carolina and Florida Atlantic
coasts as well as portions of the lower Mississippi Valley.
...20z Update...
The previous outlook largely remains on track with only minor
adjustments made. Risk probabilities were removed across eastern GA
where latest satellite imagery shows limited vertical development
within a broad cumulus field, likely owing to poor ascent given very
weak low-level convergence along a diffuse frontal zone. Latest
HRRR/RRFS guidance depicts negligible convective signals across this
region through tonight, suggesting the potential for severe
thunderstorms is low. Severe wind probabilities were similarly
trimmed across portions of southern LA where cold outflow associated
with a residual MCV over the northern Gulf is spreading northward.
Ahead of this boundary, temperatures warming into the low 80s within
a moist air mass may still support convection sufficiently deep for
a localized downburst concern (see MCD #706). Elsewhere, the
previous forecast (below) remains on track.
..Moore.. 05/11/2026
.PREV DISCUSSION... /ISSUED 1131 AM CDT Mon May 11 2026/
...Synopsis...
Upper pattern across the CONUS this morning consists of western
ridging and eastern troughing. A pair of shortwave troughs are
embedded within the parent trough, one moving through the middle OH
Valley and the other farther south across TX. A convectively
generated vorticity maximum moving across the western Gulf precedes
the TX shortwave. Farther west, a shortwave trough is moving through
the northern periphery of the upper ridging over northern MT and
adjacent southern Saskatchewan.
Recent surface analysis places a low over the eastern NC/SC border
vicinity, with a cold front extending southwestward through the
Southeast and southern AL through the far western Gulf into Deep
South TX. Another low exists farther northwest over southern
Saskatchewan, with a cold front extending south-southwestward from
this low across eastern into south-central MT.
...Eastern SC/Far Southern NC...
Regional radar imagery shows isolated thunderstorms currently
ongoing near the surface low over the eastern NC/SC border vicinity.
A modest increase in buoyancy is anticipated ahead of these storms
over the next few hours. This buoyancy coupled with strong shear
could result in a few bowing segments capable of damaging gusts.
Additional isolated thunderstorm development is anticipated late
this afternoon as the weak cold front moves eastward across SC.
Moderate buoyancy and shear will support the potential for a few
more robust/organized updrafts capable of isolated hail and/or
damaging gusts.
...Eastern FL...
Warm/moist conditions are expected today over the FL Peninsula, with
temperatures over the interior warming into the 90s. Deep westerly
flow will focus convergence along the east-coast sea-breeze, leading
to scattered afternoon thunderstorms. Sufficient deep-layer vertical
shear may result in isolated strong-severe storms producing
gusty/damaging winds and hail.
...Northern/eastern ND into eastern SD...
Despite limited low-level moisture, modest buoyancy may develop late
this afternoon/early this evening amid cooling mid-level
temperatures and increasing mid-level moisture. This buoyancy will
develop atop a deeply mixed boundary layer, supporting the potential
for strong gusts if any updrafts can deepen/mature. Given the weak
and elevated nature of the buoyancy, developing a mature updraft
capable of lightning will be difficult and the current expectation
is for most of this activity to be shallow and non-lightning
producing. That being said, gusty surface winds are possible with
any convection does develop atop the deeply mixed boundary layer.
...Coastal LA/MS/AL...
The convectively generated shortwave trough over the western Gulf
mentioned in the synopsis (and associated surface low) are expected
to progress eastward throughout the day, while the stronger
shortwave trough back across TX also progress east-southeastward.
Easterly/southeasterly low-level flow will be maintained north of
the Gulf low, increasing low-level convergence along the slow-moving
frontal zone. This convergence will be augmented by ascent attendant
to the TX shortwave, with numerous showers and thunderstorms likely.
Poor lapse rates will limit buoyancy, although moderate deep-layer
shear could support a few deeper, more organized updrafts. Primary
risk over this area is heavy rain (as noted in the WPC Day 1
Excessive Rainfall Outlook), but a few water-loaded downbursts
capable of wind damage are possible as well.
Read more
SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0208 PM CDT Mon May 11 2026
Valid 131200Z - 141200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE OHIO VALLEY AND CENTRAL APPALACHIANS AS WELL AS ACROSS
PORTIONS OF WESTERN MONTANA...
...SUMMARY...
Isolated severe storms will be possible on Wednesday across the Ohio
Valley and central Appalachians as well as portions of western and
central Montana.
... Overview ...
An amplified, yet progressive, midlevel pattern will persist on
Wednesday, with a shortwave trough moving across the northern
Rockies, an amplified ridge across the central US, and an amplified
longwave trough across the East. Embedded within the eastern
longwave trough, a shortwave trough will quickly pivot through the
basal region of the longwave trough, taking on a negative tilt as it
approaches the Mid-Atlantic Coast by the end of the forecast period.
At the surface, a low across Lower Michigan will move east across
the Great Lakes into northern New York and weaken as a new low
develops farther south along the front across the Mid-Atlantic
Region. As the initial low moves east, a surface front will also
move east across the Ohio Valley and approach the Mid-Atlantic
region by the end of the forecast period. Farther west, ahead of the
midlevel shortwave trough moving across the northern Rockies, lee
troughing will develop across the High Plains, with low-level
moisture beginning to return northward into the Central Plains.
... Ohio Valley and the Central Appalachians ...
A dry airmass will be in place across the region at the start of the
forecast period in the wake of a cool, dry anticyclone from the day
before. As the anticyclone moves east off the Atlantic Coast, modest
moisture advection will develop during the late morning into early
afternoon. The 20260511/12Z guidance suite shows varying solutions
regarding the depth and quality of the moisture return, with surface
dewpoints ranging from the upper-40Fs in the drier solutions to
perhaps 60F in the more moist solutions.
The depth and quality of the low level moisture will have an impact
on the resulting degree of instability and thunderstorm
potential/coverage. That said, the degree of forcing along the
surface front should support at least a few thunderstorms despite
instability generally around 500-1000 J/kg or less. The overall
kinematic profiles would support strong, gusty winds with any
thunderstorm that can sustain itself.
... West-central Montana into Central Montana ...
A negatively tilted shortwave trough will move across the area
during the forecast period. Despite very dry low levels initially,
increasing midlevel moisture and steep lapse rates may support a few
hundred joules per kilogram of MUCAPE during the late afternoon and
evening. As strong deep-layer ascent overspreads this environment a
few high-based thunderstorms may develop before the low-levels
moisten. Strong midlevel flow and a dry sub-cloud layer will support
at least a marginal threat for damaging wind gusts. One potential
negative for damaging wind gusts will be widespread cloud cover
associated with the increasing midlevel moisture that inhibits
destabilization. However, even in this scenario, gradient winds will
still pose a threat for damaging winds with any forced convection.
..Marsh.. 05/11/2026
Read more
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0241 PM CDT Mon May 11 2026
Valid 121200Z - 131200Z
A dry, post-frontal northwest flow regime is still expected to bring
a broad fire weather threat to portions of the northern/central
Plains and Upper Midwest on Day 2/Tuesday. A swath of stronger
sustained northwest winds between 15 and 25 mph will impact the
eastern Dakotas into southwestern MN. However, this corridor of
stronger winds will be displaced to the east of a warmer, drier
boundary layer across the northern and central High Plains where
afternoon RH reductions below 20% will be more common. Nonetheless,
the breezy northwest winds and very dry fuels (ERC values in the
95-99th percentile) should support an elevated fire weather concern
for much of the Dakotas, southwest MN into northeastern NE and
northwestern IA. Additionally, some green up of fuels could mitigate
the otherwise Critical fire weather threat across eastern
NE/northwestern IA.
..Williams.. 05/11/2026
.PREV DISCUSSION... /ISSUED 0151 AM CDT Mon May 11 2026/
...Synopsis...
On the backside of a robust midlevel trough and attendant surface
low moving eastward from the northern Plains into the upper Midwest
and eventually the Great Lakes, strong deep-layer northwesterly flow
will overspread a well-mixed post-frontal air mass over the
upper/middle MO Valley during the day. While RH reductions will be
modest in the post-frontal air mass (around 25-30 percent), 20-25
mph sustained northwesterly surface winds (with higher gusts) will
compensate and support elevated to locally critical fire-weather
conditions -- given dry/receptive fuels. If guidance trends any
lower with RH reductions, a targeted Critical area could eventually
be warranted.
...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
0505 PM CDT Mon May 11 2026
Valid 131200Z - 191200Z
...Synopsis...
A potent mid-level trough will move into the northwestern U.S. on
Day 3/Wednesday while an amplifying upper trough and corresponding
surface low move into the Northeast. A deep lee surface trough
evolves across the northern and central High Plains in response to a
mid-level wave ejecting into the northern Plains on Wednesday,
bringing enhanced downslope westerly flow to the central and
southern High Plains on Day 4/Thursday. Fire weather concerns
continue across portions of the Northern Plains Day 5/Friday as dry,
northwest flow in the wake of a cold front impacts the region. The
active wave pattern across the northern CONUS with deeper boundary
layer moisture in place could support more widespread and much
needed rainfall across the Upper Midwest beginning Day 5/Friday and
over the weekend.
...Day 3-4/Wednesday-Thursday...
...Eastern Great Basin into Upper/Lower Colorado River Basin...
A robust mid-level wave will push through the Pacific Northwest Day
3/Wednesday. Stronger southwest flow aloft ahead of the trough and
resultant deepening surface troughing across the northern Great
Basin is expected to bring fire weather concerns to considerable
portions of the Intermountain West. Southwest winds of 15-25 mph
amid low RH and drying fuels under successive days of abnormally
high temperatures should promote a fairly broad fire weather threat
across the eastern Great Basin, northern AZ and CO Plateau.
Increasing mid-level Pacific moisture across the Intermountain West,
arrival of the upper trough into the western U.S. and daytime
instability should allow for high-based convection along higher
terrain of the Upper CO River Basin, Four Corners and into western
NM where more receptive fuels reside. Both critical probability
areas for impactful dry and breezy conditions and dry thunderstorms
were expanded across this region.
...Upper Snake River Plain and Southwest Montana...
Southwest winds of 20-25 mph across eastern ID, with terrain
enhanced winds closer 30-45 mph (with higher gusts) in southwest MT
are expected Day 3/Wednesday as the sharp upper trough and
associated mid-level jet shifts overhead. Dry boundary layer
conditions amid a drying fuelscape combined with the stronger
southwest flow will enhance fire weather concerns across the Upper
Snake River Plain and southwest MT, where 40% critical probabilities
have been introduced.
...Northern Montana...
Fuels remain quite receptive across northern MT where delayed green
up has been noted. A rapidly evolving lee low in the southern
Canadian Prairies will promote a dry return flow pattern across the
northern High Plains where 40% critical probabilities were
maintained. Fast moving, high based showers and thunderstorms are
expected across central and northern MT Wednesday afternoon as broad
ascent materializes ahead of the pronounced short wave trough across
the Pacific Northwest. Limited precipitation with fast moving
thunderstorms could bring a few ignitions to northern MT where fuels
are more receptive, where a 10% dry thunderstorm probability area
was warranted. Strong westerly winds behind a cold front could
impact holdover ignitions on Day 4/Thursday where 40% critical
probabilities were introduced across southeastern MT into portions
of western ND/SD.
...Day 5/Friday - Northern Plains...
Fire weather concerns may linger across portions of the Northern
Plains on Day 5/Friday with dry, post-frontal west/northwest flow in
place, but forecast uncertainty remains precluding introduction of
critical probabilities at this time.
..Williams.. 05/11/2026
...Please see www.spc.noaa.gov/fire for graphic product...
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