RSS Mesoscale Discussions from Storm Prediction Center
No watches are valid as of Sun Jul 12 11:02:01 UTC 2026.
No Mesoscale Discussions are in effect as of Sun Jul 12 11:02:01 UTC 2026.
SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0230 AM CDT Sun Jul 12 2026
Valid 141200Z - 151200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN
NEW ENGLAND...
...SUMMARY...
Severe thunderstorms will be possible during the afternoon and
evening across portions of New England on Tuesday. Additional
strong-to-severe thunderstorms will be possible across parts of
western and central Montana.
... Synopsis ...
An expansive mid-level ridge centered over the north-central US will
begin to retrograde on Tuesday as a strong short-wave trough digs
southeast out of Canada toward New England. As the ridge builds
west, the mid-level height gradient will increase across the
northwestern US as a seasonably strong mid-level trough/closed low
remains anchored off the Washington/Oregon coasts.
... New England ...
Thunderstorms are expected to develop across portions of Quebec on
Tuesday afternoon as a strong mid-level trough and attendant surface
cold front move across the region. Ahead of this cold front,
southwesterly surface winds will transport in rich boundary layer
moisture, which will combine with diurnal heating to support MUCAPE
in the 1500-2500 J/kg range. Strong vertical shear (on the order of
50-60 knots) will overspread the region during the afternoon and
evening, which will support one or more clusters of severe
thunderstorms moving from Quebec into and across portions of New
England during the late afternoon, evening, and early morning hours.
All severe hazards will be possible with any sustained thunderstorm.
One mitigating factor for a more significant severe weather event
will be the timing of the storms. At this time, it appears
thunderstorms will be moving across New England well after peak
heating and into the overnight. Should the timing of storms be
earlier than currently expected, greater coverage of thunderstorms
may result and higher severe probabilities would be warranted.
... Portions of Western and Central Montana ...
Showers and thunderstorms are expected to develop across the higher
terrain of southwest Montana during the afternoon on Tuesday.
Surface moisture will be better (surface dewpoints in the 50Fs) than
in previous days, which should support greater afternoon buoyancy
and in turn stronger thunderstorm updrafts. Strong
south-southwesterly mid-level flow in between the trough to the west
and ridge to the east will support thunderstorm organization and
some severe potential as some of the storms move northeast off the
higher terrain.
..Marsh.. 07/12/2026
Read more
Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Sun Jul 12 2026
Valid 151200Z - 201200Z
...DISCUSSION...
An expansive mid-level ridge centered over the north-central US will
continue to retrograde during the early part of the forecast period,
before becoming centered over the Rockies toward the end of the
upcoming week. A seasonably strong mid-level trough will be
positioned over northern Quebec, positioning strong northwesterly
flow from the Upper Midwest southeast into the Mid-Atlantic and
areas to the northeast. A combination of deterministic and ensemble
forecast solutions, including AI emulators, show one or more
short-wave troughs or jet streaks moving through this enhanced flow
field.
The position of these mid-level features will help drive a surface
front southward across the eastern US that will stretch from
somewhere in the central/north-central US into the Mid-Atlantic. To
the north of this boundary, a seasonably cool, dry airmass should be
found. Along and south of this surface boundary, a very warm, moist,
and unstable airmass will be found.
As the aforementioned short-wave troughs move through the enhanced
mid-level flow, one or more rounds of thunderstorms/mesoscale
convective systems are likely to develop and move east/southeast.
Ensemble guidance continues to show a very unstable airmass (MUCAPE
in excess of 2000-3000 J/kg) along and south of where the surface
boundary resides, with strong vertical shear. The overall pattern
would seem to suggest multiple rounds/days of severe potential, with
prior days' convection likely modulating the where and intensity of
subsequent days' convection.
Given these sensitivities to prior days' convection, there will
likely be run-to-run variability within the deterministic guidance
suite as we approach the latter half of next week. Thus, while
confidence is high in severe potential during the Day 4-8 period
(and perhaps beyond), highlighting specific locations and days of
severe potential will prove challenging, with likely areas changing
from model run-to-run.
... Friday/Day 6 -- Mid-Atlantic Region ...
This evening's deterministic guidance suite (20260712 00 UTC), along
with yesterday morning's deterministic guidance suite (20260711 12
UTC), is faster moving the surface boundary south than last night's
guidance suite (20260711 00 UTC). However, the overall ensemble
guidance continues to suggest severe potential across the region,
owing to differences in the position of the surface boundary and the
timing of mid-level vorticity maxima. Severe probabilities (15%)
have been retained with this forecast in a nod to the ensemble
guidance suite, but if the current trend of pushing the surface
boundary farther south on Thursday (Day 5) continues, severe weather
probabilities may need to be removed as the surface boundary will
push south of the better deep-layer shear.
Read more
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0149 AM CDT Sun Jul 12 2026
Valid 121200Z - 131200Z
...CRITICAL FIRE WEATHER AREA FOR SOUTHERN MONTANA INTO PORTIONS OF
IDAHO AND NORTHERN WYOMING...
...Synopsis...
An upper-level trough and associated jet streak is forecast to
progress east-northeastward from British Columbia into the interior
Canadian provinces today as an upper-level ridge moves from the
Great Basin into the High Plains. Residual flow across the Pacific
Northwest from the ejecting trough and a deepening surface low
across eastern Montana will be responsible for Elevated to Critical
fire-weather concerns across the Intermountain West to the northern
High Plains.
...Southern Montana into portions of Idaho and northern Wyoming...
As a surface low deepens over eastern Montana this afternoon into
the evening, the intensifying surface pressure gradient will result
in sustained winds of 20-25 MPH across much of the area. Relative
humidity of 10-15% is expected across portions of Idaho into
southwestern Montana, and could get as low as 5-10% in south-central
Montana into northern Wyoming. With ERCs largely in the 80th-95th
annual percentiles across the region, Critical fire-weather
conditions are forecast. As the surface low moves eastward and a
cold front moves through the area, winds will shift from largely
southerly to west-northwesterly but should still be gusting 20-25
MPH.
...Northern High Plains...
Strong southeasterly surface flow ahead of the deepening cyclone
should result in sustained 15-20 MPH winds across the far western
Dakotas into portions of Wyoming and Montana. Relative humidity is
forecast to be in the range of 5-15%, getting more moist with
eastward extent. While ERCs are largely in the 90th-95th annual
percentile range, this guidance does not account for live fuels and
the current state of green vegetation. Given the uncertainty in the
quality of fuels with this eastward extent, Elevated fire-weather
highlights have been maintained -- though periods of Critical
meteorological conditions will be possible.
...Southern Oregon into portions of northern Nevada and
California...
Lingering dry and breezy conditions in the wake of the ejecting
mid-level jet streak will persist this afternoon across portions of
northeastern California/northwestern Nevada into southern Oregon.
Winds of 15-20 MPH and relative humidity around 15-20% will overlap
with modestly receptive fuels, resulting in Elevated fire-weather
concerns.
...Southern and Central California...
Isolated to scattered high-based showers appear possible across
portions of California. Occasional lightning is possible, but
limited buoyancy puts the likelihood at less than 10% coverage.
Portions of the Mojave and Sonoran Deserts may see a mix of wet and
dry thunderstorm activity, but uncertainty in the coverage and
rainfall amounts precludes highlights at this time.
..Halbert.. 07/12/2026
...Please see www.spc.noaa.gov/fire for graphic product...
Read more
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0152 AM CDT Sun Jul 12 2026
Valid 131200Z - 141200Z
...Synopsis...
As an upper-level trough and associated jet streak translates
eastward across the Canadian Prairie on Monday, ridging will
intensify over much of the Central US. Southerly and southeasterly
flow around the western periphery of this ridge will transport
monsoonal moisture northward into the Western US, resulting in a few
pockets of dry/wet thunderstorms. Additionally, dry and breezy
conditions across the central and northern High Plains will support
Elevated fire-weather concerns.
...Northern Colorado into Wyoming and portions of western South
Dakota...
Dry and windy conditions are forecast across portions of the central
and northern High Plains on Monday, as surface winds respond to a
lee trough. These winds are anticipated to be around 15-20 MPH, with
relative humidity varying between 10-20%. Dead fuels guidance has
ERCs in the 95th annual percentile range, but some semi-recent
rainfall and live vegetation will serve to reduce some of the
volatility of those fuels. At least Elevated fire-weather concerns
are forecast at this time.
...Southwestern Montana and Northeastern California/Northwestern
Nevada...
Monsoonal moisture transported northward along the western periphery
of the mid-level ridge will bring showers and thunderstorms to
portions of the Intermountain West. While anticipated to be a mix of
wet and dry thunderstorms, isolated dry thunderstorm highlights were
introduced to portions of northeastern California into northwestern
Nevada on Monday. This mix of wet and dry thunderstorms will overlap
with receptive fuels, and lightning on the periphery of the wetter
downdrafts will still be capable of wildfire ignitions.
In far southwestern Montana, a more classic isolated dry
thunderstorm environment is forecast. Precipitable water content of
0.5-0.75" is forecast where HREF/REFS guidance shows thunderstorm
activity developing. Proximity soundings to this thunderstorm
activity shows deep inverted-V profiles and relatively fast storm
motions. This should result in limited precipitation efficiency of
thunderstorm activity overlapping with critically receptive fuels.
..Halbert.. 07/12/2026
...Please see www.spc.noaa.gov/fire for graphic product...
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