677
ACUS02 KWNS 190602
SWODY2
SPC AC 190600

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

$$