ACUS48 KWNS 060853
SWOD48
SPC AC 060852

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0352 AM CDT Fri Jun 06 2025

Valid 091200Z - 141200Z

...DISCUSSION...
A large MCS may be ongoing across the Ark-La-Tex vicinity on
D4/Monday morning. This MCS and attendant flow enhancement with its
MCV may support scattered damaging wind potential into the afternoon
downstream across the Deep South. How extensive an organized wind
threat persists is quite nebulous, given background mid-level
westerlies being weaker across the Southeast compared to prior days.

Sub-15 percent severe potential remains apparent across the Upper OH
Valley to Lower Great Lakes on D4/Monday, shifting east into the Northeast/Mid-Atlantic States on D5/Tuesday. A belt of strong
mid-level southwesterlies ahead of broad Great Lakes trough should
overlap parts of a weak cold front arcing south from a primary
surface cyclone over northeast ON to James Bay. Substantial
instability ahead of the front appears uncertain with progged weak
mid-level lapse rates and muted boundary-layer heating where the
stronger flow resides.

During D6-8/Wednesday-Friday, guidance continues to signal a
reduction in severe potential, as predominantly weak deep-layer
shear overlaps areas of moderate to large buoyancy.

..Grams.. 06/06/2025

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ACUS48 KWNS 070842
SWOD48
SPC AC 070841

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0341 AM CDT Sat Jun 07 2025

Valid 101200Z - 151200Z

...DISCUSSION...
Sub-15 percent severe potential remains apparent over the Mid-Atlantic/Northeast States on D4/Tuesday before a cold front
moves offshore. Instability progs remain weak where at least
moderate deep-layer shear is anticipated. It seems plausible that
the northern extent of larger buoyancy will be suppressed south in
the wake of extensive convection through D3 across the Southeast.

On D5-6/Wednesday-Thursday, guidance has trended towards some
amplification of a minor southern-stream shortwave impulse as it
drifts across the southern Great Plains. This could foster mesoscale
corridors of modest shear overlapping plentiful buoyancy in the
south-central states.

Western Gulf moisture will spread north and encompass much of the
central states through next weekend. Various shortwave impulses over
the Northwest may support multiple bouts of mesoscale-driven severe
potential along the northern periphery of the expansive Great Plains
buoyancy plume.

..Grams.. 06/07/2025

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ACUS48 KWNS 080849
SWOD48
SPC AC 080847

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0347 AM CDT Sun Jun 08 2025

Valid 111200Z - 161200Z

...DISCUSSION...
Guidance trends remain supportive of a more active pattern across
the northern High Plains to the Upper Midwest. GEFS-based ML
guidance from SPC and NSSL are now highlighting multiple days with
mesoscale areas of 15 percent probabilities, mainly over the
northern High Plains. Western Gulf moisture will spread north and
encompass much of the central states through next weekend. Various
shortwave impulses ejecting into the Northwest may support multiple
bouts of mesoscale-driven severe potential downstream along the
northern periphery of the expansive Great Plains buoyancy plume. The
initial impulse that is expected to reach northern CA by 12Z
Wednesday has poor predictability with its downstream evolution into
the North-Central States.

Low-probability severe potential may persist for several days with a
minor southern-stream shortwave impulse drifting east from the
southern Great Plains. This could foster daily mesoscale corridors
with a severe threat, as modest shear overlaps plentiful buoyancy
initially over the South-Central States.

..Grams.. 06/08/2025

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ACUS48 KWNS 090849
SWOD48
SPC AC 090847

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0347 AM CDT Mon Jun 09 2025

Valid 121200Z - 171200Z

...DISCUSSION...
Guidance remains supportive of a more active pattern across the
northern High Plains to the Upper Midwest. GEFS-based ML guidance
from SPC and NSSL depict mesoscale areas of 15 percent
probabilities, centered on eastern MT to the Dakotas. While
predictability for a specific day remains too low, the signal exists
for increasing potential during the weekend to early next week.

The initial low-amplitude shortwave trough over WY/eastern MT at 12Z
Thursday is progged to dampen as it moves east into the Upper
Midwest. An area-of-interest is evident over western SD and the NE
Panhandle on D4/Thursday afternoon, but a favorable buoyancy/shear
combination is too spatially confined for a 15 percent highlight.

A broad swath of moderate to strong mid-level southwesterlies may
persist for multiple days across the Northwest, downstream of a
large-scale trough near the West Coast. At the same time, the
expansive buoyancy plume over the central states should increase
northwestward, building higher CAPE into the northern High Plains
this weekend. Still, poor predictability persists with the
spatiotemporal details of individual shortwave impulses that may
support daily severe threats on D6-8/Saturday-Monday.

..Grams.. 06/09/2025

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ACUS48 KWNS 100849
SWOD48
SPC AC 100848

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0348 AM CDT Tue Jun 10 2025

Valid 131200Z - 181200Z

...DISCUSSION...
Models are in good agreement with the overall pattern through about
Sunday/D6, depicting upper ridging over the northern Plains and
rising heights across the Northeast and general troughiness over the
Northwest. During that same period, the disturbance over the
southern Plains is forecast to lift toward the mid MS Valley with
weakening trend.

The greatest risk of severe storms will generally stretch from the
northern Rockies into the northern Plains, as weak but backed
low-level winds maintain a moist plume out of the central Plains and
into MT and the Dakotas.

On Friday/D4, scattered strong storms may occur over central MT,
beneath modest southwest winds aloft and with around 1000 J/kg
MUCAPE. Instability will build further in the Saturday/D5 to
Sunday/D6 time frame, with greater storm coverage expected. However,
winds aloft will be marginal. Still, developing west to northwest
flow aloft could eventually result in an MCS pattern with attendant
wind potential. Predictability is low at this time, but the northern
and central Plains region will be monitored over the next several
days for potential categorical risk outlines.

..Jewell.. 06/10/2025

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ACUS48 KWNS 110839
SWOD48
SPC AC 110838

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0338 AM CDT Wed Jun 11 2025

Valid 141200Z - 191200Z

...DISCUSSION...
For Saturday/D4 into Sunday/D5, moderate southwest flow aloft will
remain over the Pacific Northwest and toward the northern Rockies,
with a gradual flattening of the upper ridge over the northern
Plains. Then through Wednesday/D8, modest west/northwest flow aloft
is likely to persist over the High Plains. Models diverge greatly
after this time frame. However, this pattern will generally favor
daily thunderstorms along the length of the High Plains, from MT
into eastern NM during the afternoon, and persisting into parts of
the Great Plains during the evenings.

The primary driver of severe potential will be a large area of
moderate to strong instability with 2000-3000+ J/kg MUCAPE
developing daily. As storms move off the higher terrain, corridors
of wind damage may materialize. Predictability is low this far out,
but categorical risk upgrades appear likely as these periods get
closer in time. The primary risk appears to be damaging winds, but
sporadic large hail is possible with the late afternoon activity.

..Jewell.. 06/11/2025

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ACUS48 KWNS 120835
SWOD48
SPC AC 120833

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0333 AM CDT Thu Jun 12 2025

Valid 151200Z - 201200Z

...DISCUSSION...
During the Sunday/D4 to Monday/D5 period, an upper ridge is forecast
to remain over the Plains, with modest southwest flow aloft over the
West. Models suggest that around Tuesday/D6, the upper ridge will
break down over the central/northern Plains, although the amplitude
and track of the wave is in question. Ample low-level moisture will
be in place from the Plains to the East Coast, with mid to upper 60s
F as far north as southern parts of the Great Lakes.

As a result of this large area of moisture and instability, widely
scattered thunderstorms will be common each day. The northern Plains
appears to have the greatest change of organized severe storms
includes MCS/s, but predictability is clearly low at this time with
the uncertain wave. However, it appears that the Tuesday/D6 to
Wednesday/D7 time frame may yield a corridor of organized damaging
wind potential over parts of the northern and central plains to
Midwest, and these trends will continue to be monitored.

..Jewell.. 06/12/2025

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ACUS48 KWNS 130901
SWOD48
SPC AC 130859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Fri Jun 13 2025

Valid 161200Z - 211200Z

...DISCUSSION...
...Monday/Day 4 to Wednesday/Day 6...
A mid-level ridge across the Great Plains is forecast to become less
amplified on Monday, as multiple shortwave troughs move through
westerly flow across the north-central states. A moist airmass is
forecast across much of the central and northern Plains, where
moderate to strong instability appears likely to develop by
afternoon. Along the northern edge of the stronger instability,
scattered convective initiation is expected. The instability,
combined with moderate deep-layer shear, should support a severe
threat. Large hail and severe wind gusts will be possible during the
afternoon and evening.

The mid-level ridge is forecast to move eastward into the Missouri
Valley on Tuesday, as a trough moves into the Rockies. At the
surface, a moist airmass is forecast from the central Plains into
the Missouri Valley, where moderate to strong instability appears
likely to develop by afternoon. Large-scale ascent ahead of the
approaching trough is forecast to move into the central Plains
Tuesday evening. As a result, a large area of thunderstorms is
forecast to develop from northern Kansas into much of Nebraska.
Model forecasts suggest that moderate deep-layer shear will be in
place, which would support a large hail and wind-damage threat.

The mid-level trough is forecast to move across the Great Plains on
Wednesday. A moist airmass is forecast to remain in place to the
east of the trough across the lower Missouri and Mississippi
Valleys. Ahead of the trough, moderate instability is forecast by
afternoon. Thunderstorm development is expected with this unstable
airmass from eastern Kansas northeastward into the mid to upper
Mississippi Valley. A severe threat will be possible. The greatest
potential for severe storms could be from northern Missouri into
southern Wisconsin, along and near the axis of a low-level jet.

...Thursday/Day 7 and Friday/Day 8...
From Thursday into Friday, the mid-level trough, and an associated
cold front, is forecast to move from the mid Mississippi Valley to
the Eastern Seaboard. A moist and unstable airmass should be in
place ahead of the trough. Thunderstorm development will be possible
along parts of the front, and across the warm sector. Although a
severe threat may develop as instability increases during the day,
the timing of the front remains questionable and predictability is
low.

..Broyles.. 06/13/2025

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ACUS48 KWNS 140900
SWOD48
SPC AC 140859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Sat Jun 14 2025

Valid 171200Z - 221200Z

...DISCUSSION...
...Tuesday/Day 4 and Wednesday/Day 5...
A mid-level trough is forecast to move into the High Plains on
Tuesday, as a cold front moves southward into the central Plains.
Ahead of the front, a moist and unstable airmass is forecast by
afternoon from Kansas and southeastern Nebraska into northern
Missouri. As surface temperatures warm during the day, thunderstorm
development will likely take place along parts of the front.
Moderate deep-layer shear is forecast across much of the region,
suggesting that storms should become organized. Supercells and short
intense line segments will be possible, with large hail and wind
damage as the primary threats.

The mid-level trough is forecast to move eastward through the
central states on Wednesday, as a cold front advances southeastward
into the lower Missouri Valley and western Great Lakes. Ahead of the
front, an axis of moderate instability is forecast to be in place by
afternoon. Thunderstorm development will be likely along parts of
the front. Moderate deep-layer shear is forecast along and near much
of the instability axis, suggesting that a severe threat will again
be possible during the afternoon and evening.

...Thursday/Day 6 to Saturday/Day 8...
The mid-level trough is forecast to move eastward into the Northeast
on Thursday. Ahead of the trough and its associated cold front,
moderate instability is expected to develop by afternoon.
Thunderstorm development will be most likely from parts of southern
New England southwestward into the Mid-Atlantic. Deep-layer shear
should be sufficient for an isolated severe threat. However, there
is considerable uncertainty due to the issues of frontal timing and
instability magnitude.

From Friday into Saturday, a mid-level ridge is forecast to move
eastward from the northern Plains into the Great Lakes. Although a
moist and unstable airmass will likely be in place across the
north-central U.S., large scale ascent should be weak across most of
the region. For this reason, predictability is low concerning any
potential severe threat.

..Broyles.. 06/14/2025

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ACUS48 KWNS 150900
SWOD48
SPC AC 150859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Sun Jun 15 2025

Valid 181200Z - 231200Z

...DISCUSSION...
...Wednesday/Day 4 and Thursday/Day 5...
A mid-level trough is forecast to move through the Upper Midwest on
Wednesday, as a cold front advances southeastward into the lower
Missouri and mid-Mississippi Valleys. Ahead of the front, moderate
instability is forecast to develop by afternoon. Thunderstorms
appear likely to form along parts of the front, with several
clusters or line segments moving eastward toward the instability
axis during the late afternoon and early evening. Moderate
deep-layer shear should support severe storms with large hail and
wind damage as the primary threats.

The mid-level trough is forecast to move into the lower Great Lakes
and upper Ohio Valley on Thursday, as the cold front advances into
the central Appalachians. As the airmass ahead of the front
destabilizes, scattered thunderstorms are expected to form along and
ahead of the front. The models suggest that moderate deep-layer
shear will be in place across much of the northeastern U.S., which
will likely support organized storms. Damaging winds gusts will be
the most likely severe threat.

...Friday/Day 6 to Sunday/Day 8...
A shortwave mid-level ridge is forecast to move into the upper
Mississippi Valley on Friday. The ridge is forecast to remain over
the region on Saturday as mid-level heights rise. Beneath the ridge,
a moist and unstable airmass will likely be in place from the lower
to mid Missouri Valley northeastward into the western Great Lakes.
Within this airmass, isolated thunderstorm development should take
place both Friday and Saturday afternoon. Instability and deep-layer
shear appear sufficient for a localized severe threat. However, the
presence of the ridge introduces uncertainty as to where the
greatest potential for convection will be. For this reason,
predictability is low.

On Sunday, a mid-level trough is forecast to develop over the
Rockies as a ridge moves into the Great Lakes region. Although a
moist and unstable airmass should be located over parts of the
northern and eastern U.S., large-scale ascent and mid-level flow is
forecast to be relatively weak in most areas. For this reason, any
severe potential is expected to remain isolated.

..Broyles.. 06/15/2025

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