RSS Mesoscale Discussions from Storm Prediction Center
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1252 AM CDT Thu Jun 19 2025
Valid 191200Z - 201200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE
MIDDLE ATLANTIC...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY...
...SUMMARY...
Severe thunderstorms are expected across much of the Middle Atlantic
region, and to a lesser extent into the Carolinas and over portions
of New England. Severe wind gusts are the primary concern. Isolated
hail and wind threat is expected across the northern Plains into
Minnesota, primarily during the evening/overnight.
...Eastern U.S...
Seasonally strong upper trough is currently located over IL and
should advance into the OH Valley by 18z as stronger 500mb flow
develops across western PA/NY. With time, 50+kt flow should
translate into the Middle Atlantic, coincident/just ahead of the
primary synoptic front. Latest model guidance suggests modest 0-3km
lapse rates will develop by mid day as the boundary layer warms
ahead of the wind shift, especially from the Carolinas into Upstate
NY. In fact, much of the I-95 corridor over the Middle Atlantic will
warm quickly through the 80s to near 90F, effectively removing any
inhibition. As a result, convection should readily develop within a
very moist environment (PWs 1.75-2 inches) characterized by MLCAPE
in excess of 2000 J/kg. Forecast soundings exhibit deep
west-southwesterly flow with 0-6km bulk shear around 30kt. These
profiles favor organized line segments and clusters, and severe wind
gusts will likely be noted with the most robust activity. Convection
should spread off the Middle Atlantic Coast during the evening
hours.
...Northern Plains/Upper MS Valley...
Latest water-vapor imagery depicts a short-wave trough over
southeast BC. This feature will suppress heights across southern
AB/SK early in the period, and a secondary disturbance will eject
across southern SK during the evening. These features are expected
to encourage convective development along the cool side of a
boundary that will be draped from the upper MS Valley-central
ND-southern SK. Low-level warm advection should aid bouts of
elevated convection, but the primary concern is with thunderstorms
that evolve during the early evening. Storms that form over
southeastern SK and southwestern MB will spread southeast toward a
region of increasing low-level warm advection. LLJ is forecast to
increase across eastern SD into southwest MN during the late
evening. Elevated supercells should develop ahead of the Canadian
convection as the LLJ strengthens into the upper Red River Valley.
An MCS may ultimately evolve over the upper MS Valley late in the
period as the LLJ shifts into southeast MN/southwestern WI. Hail and
wind are the primary concern with this activity.
..Darrow/Weinman.. 06/19/2025
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SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Thu Jun 19 2025
Valid 201200Z - 211200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS 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. Significant severe
weather is possible.
...Synopsis...
A seasonably deep mid/upper-level cyclone will move across the
Pacific Northwest on Friday, as the attendant large-scale trough
begins to impinge on the central/northern Great Plains. Downstream,
an upper ridge will gradually shift eastward from the southern
Plains toward the lower MS Valley.
A surface low will deepen across the northern High Plains, with
increasing low-level moisture expected near and east of the low and
trailing dryline/surface trough, and also near/north of a warm front
that will extend east/northeast of the low.
...Dakotas into the Upper Midwest/Great Lakes...
Strong to extreme buoyancy will develop Friday afternoon across much
of the central/northern Plains into the Upper Midwest. Warming
temperatures aloft will result in substantial capping across the
warm sector, and coverage/location of storms within an otherwise
volatile environment remains very uncertain.
Most guidance suggests a mid/upper-level shortwave will emerge from
the western trough and move across the northern Plains sometime
during the afternoon/evening, though differences remain regarding
the timing and amplitude of this shortwave. This shortwave trough
could aid in isolated storm development by late afternoon/early
evening, primarily near or north of the surface low and warm front.
Veering wind profiles will support supercells, with a conditional
threat for very large hail, isolated severe gusts, and also some
tornado potential if any supercells can become surface-based.
Some increase in storm coverage is expected Friday evening into the
overnight, in response to a nocturnally strengthening low-level jet.
Initial development within this regime could be supercellular, with
potential for upscale growth with time. An intense MCS capable of
producing significant severe gusts could evolve with time. Even if
this does not occur, one or more smaller clusters may develop and
track east-southeastward north of the warm front, with very large
buoyancy and sufficient deep-layer shear supporting a threat of
large to very large hail and severe gusts.
Greater severe probabilities may be needed if confidence increases
regarding a sufficient coverage of supercells, and/or development of
an intense MCS.
...Montana...
Low-level easterly flow will support some moistening across much of
MT on Friday, though guidance continues to vary regarding the
magnitude of destabilization during the afternoon and evening.
Large-scale ascent associated with the approaching mid/upper-level
trough will support scattered storm development across western MT
during the afternoon, with sufficient deep-layer shear for some
storm organization. Depending on the extent of downstream
destabilization, some threat for strong to potentially severe storms
may spread into parts of central/eastern MT Friday evening. Greater
severe probabilities may be needed into parts of western/central MT
depending on trends regarding destabilization.
...South-central High Plains...
High-based convection may develop Friday afternoon across parts of
CO/NM, within a very warm and well-mixed environment. While this
convection should generally be disorganized, localized severe gusts
could accompany this convection before it subsides during the
evening.
...Lower Great Lakes...
A northwesterly flow regime will become established across the lower
Great Lakes vicinity on Friday. While large-scale ascent will remain
rather nebulous, and destabilization is expected to be rather
modest, elongated hodographs will conditionally support some storm
organization. A few strong storms capable of locally gusty winds and
perhaps marginal hail cannot be ruled out during the afternoon and
evening.
..Dean.. 06/19/2025
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SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0230 AM CDT Thu Jun 19 2025
Valid 211200Z - 221200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE
NORTHERN PLAINS INTO THE UPPER MIDWEST AND GREAT LAKES...
...SUMMARY...
Strong to locally severe storms are possible Saturday from the
northern Great Plains into the Upper Midwest and Great Lakes.
...Synopsis...
The large-scale pattern on Saturday will not change appreciably,
with a seasonably deep upper trough over the West, and an amplified
upper ridge over the Southeast and Ohio Valley. A lee trough and
surface low will remain in place over the central/northern High
Plains, with an expansive area of rich low-level moisture east of
the low/trough across the Plains and upper Midwest.
...Upper Midwest/Great Lakes...
Confidence is quite low regarding the details of severe-storm
potential on Saturday, though conditional potential remains evident
along the periphery of the upper ridge. An MCS that may develop late
on D2/Friday may be moving across parts of the northern Great Lakes
at the start of the period (and possibly posing a severe-wind
threat), though it is possible that the bulk of this MCS will be in
Ontario through the day. This MCS (or its remnant MCV) may move
southeastward toward the lower Great Lakes and NY/PA by evening, and
could pose some severe threat if it does not become displaced from
the buoyancy reservoir to its southwest.
Some redevelopment cannot be ruled out in the wake of the potential
morning MCS into the upper Great Lakes/Midwest. Buoyancy and shear
will remain favorable for organized severe storms, but confidence is
low regarding coverage and location at this time.
...Northern Plains...
Strong storms that develop on D2/Friday be ongoing Saturday morning
across eastern MT, and could pose an isolated severe hail/wind
threat. Guidance varies regarding instability/moisture across
eastern MT later in the day, but if some diurnal destabilization can
occur, then ascent related to the western trough may aid in
additional strong storm development.
Stronger instability will reside across the Dakotas, and the
greatest relative threat for a couple supercells and/or an organized
storm cluster currently appears to be across parts of ND during the
afternoon and evening. However, confidence is too low for higher
probabilities at this time.
..Dean.. 06/19/2025
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