RSS Mesoscale Discussions from Storm Prediction Center
No watches are valid as of Wed Jun 18 10:33:01 UTC 2025.
No Mesoscale Discussions are in effect as of Wed Jun 18 10:33:01 UTC 2025.
SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1254 AM CDT Wed Jun 18 2025
Valid 191200Z - 201200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF NEW
ENGLAND INTO THE MID ATLANTIC AND NORTH CAROLINA...
...SUMMARY...
Strong to potentially severe thunderstorms are forecast on Thursday
from parts of New England into the Mid Atlantic and Carolinas.
...Synopsis...
A seasonably deep mid/upper-level trough is forecast to move from
the lower Great Lakes region into the Northeast and Mid Atlantic on
Thursday. A surface low will move across parts of Quebec during the
day and evening, as a trailing cold front moves across parts of New
England, the Mid Atlantic, and Carolinas/Southeast.
An upstream midlevel shortwave trough will move across parts of
northern MN into WI and upper MI by evening. An amplified
mid/upper-level trough will move gradually eastward across the
western CONUS, as an upper-level ridge initially over the southern
Rockies begins to break down and shift eastward. In response to this
trough, a surface low will gradually deepen across the northern High
Plains.
...New England into the Mid Atlantic/Southeast...
Relatively rich low-level moisture will stream northward ahead of
the front approaching New England and the Mid Atlantic during the
day on Thursday. Moderate buoyancy may develop as far north as
northern NY/VT, with pockets of stronger heating/destabilization
farther south into the Mid Atlantic and Carolinas/Southeast.
The strongest deep-layer flow/shear is still expected from
PA/northern NJ northward into New England, where wind profiles will
be conditionally supportive of supercells and organized bowing
segments. Damaging winds and perhaps a tornado could accompany the
strongest storms in this area.
Farther south into the southern Mid Atlantic and Carolinas,
deep-layer flow will be somewhat unidirectional and weaker, but
still sufficient for some organized convection. Clusters capable of
producing scattered wind damage will be possible, especially in
areas where stronger diurnal heating/destabilization occurs.
Deep-layer flow will be rather weak into parts of MS/AL/GA/SC, but
the glancing influence of the mid/upper-level trough and relatively
large MLCAPE and PW will support storms capable of producing
isolated strong/damaging gusts.
...Southwest MT and vicinity...
Weak midlevel height falls are still expected across parts of
western MT Thursday afternoon/evening, in response to the
approaching mid/upper-level trough. Low-level moisture will remain
limited, but strong diurnal heating will support high-based storm
development. Steep low-level lapse rates and relatively strong
midlevel flow will result in potential for isolated severe gusts
during the afternoon and evening as convection spreads eastward.
...Upper Midwest...
Low-level warm advection related to the southeastward-moving
midlevel shortwave trough may aid in storm development on Thursday
from northern MN into parts of WI and upper MI. Moderate instability
and sufficient deep-layer shear will support potential for a few
stronger cells/clusters capable of producing large hail and damaging
wind. Additional strong to locally severe storms may redevelop later
Thursday night across parts of this region, in response to a
nocturnally strengthening low-level jet.
...Northern Plains...
Diurnal heating of an increasingly moist airmass will result in
moderate to strong buoyancy across parts of the northern Plains by
Thursday afternoon. Deep-layer shear will be sufficient for
organized storms, but diurnal storm development remains highly
uncertain amid background midlevel height rises associated with a
building ridge. Development of a storm or two cannot be ruled out
through evening near a surface trough/weak dryline. Elevated storm
coverage may increase somewhat Thursday night in response to a
strengthening low-level jet, which could pose a threat of hail and
localized strong gusts.
..Dean.. 06/18/2025
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SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0230 AM CDT Wed Jun 18 2025
Valid 201200Z - 211200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
NORTHERN PLAINS INTO THE UPPER MIDWEST/GREAT LAKES...
...SUMMARY...
Severe thunderstorms may develop Friday into Friday night across
parts of the northern Plains and upper Midwest.
...Synopsis...
An upper-level ridge is forecast to amplify on Friday from the
southern Plains into parts of the MS/OH Valleys, as a seasonably
deep mid/upper-level trough moves gradually eastward over the West.
Rich low-level moisture will continue to stream northward to the
east of a deepening lee surface cyclone across the northern High
Plains. Multiple shortwaves may emanate out of the western trough
and traverse the periphery of the building ridge from the northern
Rockies/Plains into the Upper Midwest and parts of Great Lakes.
...Northern Great Plains into the Upper Midwest/Great Lakes...
Uncertainty remains high regarding the details of convective
evolution Friday into Friday night, but potential for severe storm
development within a relatively volatile environment remains
evident.
To the east of the High Plains cyclone and trailing surface trough,
and along/south of an effective warm front, strong to extreme
buoyancy will develop Friday afternoon across parts of the
central/northern Plains into the Upper Midwest. Details of diurnal
storm development (if any) within this regime remain unclear.
Warming temperatures aloft may tend to suppress development across
the warm sector, but shortwaves emanating out of the western
mid/upper-level trough may aid in development of an isolated
supercell or two near the surface trough/dryline and/or effective
warm front. Any surface-based development within this regime could
pose a threat for all severe hazards.
A somewhat more likely scenario is for storms to expand in coverage
near/north of the warm front during the evening, in response to a
strengthening low-level jet and related warm-advection regime. Large
to extreme buoyancy and favorable deep-layer shear will support
organized convection, with upscale growth into a potentially intense
MCS possible with time. At this time, the most likely MCS corridor
appears to be somewhere from eastern ND into central/northern MN,
northern WI, and upper MI, though uncertainty remains high due to
varying guidance solutions regarding the location of the warm front
and evolution of the low-level jet.
Despite the remaining uncertainty, a Slight Risk has been added
given the conditional potential for significant severe weather. Some
adjustments to this area will likely be needed with time, along with
possible upgrades.
...Montana...
Low-level easterly flow will transport modest moisture into parts of
central/western MT during the day on Friday. Increasingly difluent
upper-level flow associated with the deep western trough will
support development of scattered to numerous thunderstorms through
the day into Friday night. Elongated hodographs will support
organized storms, with a threat of at least isolated hail and strong
to severe gusts with initial convection over western MT. One or more
clusters may move into central and northeast MT by evening, with a
continued threat of severe gusts and hail. Depending on trends
regarding destabilization, greater severe probabilities may
eventually be needed.
...Lower Great Lakes into the Northeast...
Modest low-level moistening is possible during the day on Friday
from the lower Great Lakes into the Northeast, within a developing
northwesterly flow regime in the wake of a departing mid/upper-level
trough. While wind profiles may become somewhat favorable for
organized convection, relatively cool post-frontal conditions and
generally weak midlevel lapse rates will tend to limit
destabilization, and any foci for robust storm development are not
clear at this time.
..Dean.. 06/18/2025
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Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0342 AM CDT Wed Jun 18 2025
Valid 211200Z - 261200Z
...DISCUSSION...
...D4/Saturday...
An amplified upper-level pattern will continue into Saturday, with a
prominent ridge extending from the Southeast into the Midwest and
Ohio Valley, and a deep trough over much of the West. Large to
extreme buoyancy will again develop across parts of the
central/northern Plains and Upper Midwest, but the influence of the
ridge will tend to suppress storm development across the warm
sector.
While differing in the details, some extended-range guidance
suggests that an MCS (or at least its remnant MCV) that develops
late on D3/Friday will move across the far northern Great Lakes and
adjacent parts of Ontario on Saturday, and potentially into parts of
the lower Great Lakes by Saturday evening. Should such an evolution
occur, some severe threat could accompany this system, but
predictability for such a scenario at this range is inherently low.
Farther west, there is substantial spread in guidance regarding the
magnitude of low-level moisture and instability across parts of MT
and northern WY into western ND on Saturday. However, if stronger
flow associated with the western trough can impinge upon favorable
instability, then an organized severe threat could evolve during the
afternoon and evening.
...D5/Sunday...
The western trough is generally forecast to take on more of a
positive tilt and eventually deamplify on Sunday, as a substantial
shortwave and midlevel jet maximum eject across parts of the
northern High Plains. As this occurs, a cold front will move across
parts of the northern/central Plains. At this time, it appears the
organized severe threat may be limited by very warm temperatures
aloft and a tendency for stronger deep-layer flow to lag behind the
front.
Strong buoyancy may spread into parts of the Ohio Valley and
Northeast on Sunday. Some organized severe potential could develop
within the instability gradient along the periphery of the ridge,
though mesoscale details remain highly uncertain at this time.
...D6/Monday - D8/Wednesday...
Uncertainty increases into early next week regarding evolution of
the synoptic pattern, though guidance generally suggests that an
upper ridge will remain prominent across parts of the eastern CONUS,
while a weak upper trough will persist across parts of the West into
the northern and central Plains. While some severe potential could
evolve across parts of the Great Plains, Great Lakes, and Northeast
along the periphery of the ridge, details regarding favored days and
locations remain highly uncertain.
Read more
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0150 AM CDT Wed Jun 18 2025
Valid 181200Z - 191200Z
...Synopsis...
Within the base of a deep midlevel low off of British Columbia, a
shortwave trough and related midlevel westerly speed maximum will
overspread the Pacific Northwest. As a result, dry/breezy downslope
flow will develop in the Columbia Basin during the afternoon. Here,
around 15 mph sustained westerly surface winds (higher in the
Cascade Gaps) and 20-25 percent RH will favor elevated to locally
critical fire-weather conditions over dry fuels.
..Weinman.. 06/18/2025
...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
0150 AM CDT Wed Jun 18 2025
Valid 191200Z - 201200Z
...CRITICAL FIRE WEATHER AREA FOR NORTHWESTERN NEVADA...
...CRITICAL FIRE WEATHER AREA FOR PARTS OF EASTERN NEVADA...WESTERN
UTAH...AND FAR NORTHWESTERN ARIZONA...
...Synopsis...
Preceding a large-scale trough over the West Coast, moderate-strong
deep-layer southwesterly flow will overspread central CA into the
Great Basin through the afternoon. As this occurs, the surface
pressure gradient will tighten across much of the West -- peripheral
to surface lows evolving over the northern Great Basin and the Lower
CO River Valley.
...Great Basin...
Strong diurnal heating amid a dry antecedent air mass will result in
a deeply mixed boundary layer across much of the Great Basin --
characterized by widespread surface temperatures in the 90s to 100 F
and single-digit RH. At the same time, the deep boundary-layer
mixing into the strong flow aloft, coupled with a tightening
pressure gradient, will yield an expansive area of 25 mph sustained
southwesterly surface winds (with higher gusts). Over portions of
northwest NV and eastern NV/western UT, these hot, dry, and windy
conditions over receptive fuels will lead to critical fire-weather
conditions.
...San Joaquin Valley and adjacent areas...
The tightening pressure gradient and boundary-layer mixing into the
enhanced flow aloft will favor dry/breezy conditions in the San
Joaquin Valley and adjacent areas during the afternoon -- where
elevated fire-weather conditions are expected over any dry/receptive
fuels.
..Weinman.. 06/18/2025
...Please see www.spc.noaa.gov/fire for graphic product...
Read more
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