SPC Jul 6, 2025 0100 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 0100Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0800 PM CDT Sat Jul 05 2025

Valid 060100Z - 061200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER FAR
SOUTHEASTERN MONTANA...NORTHEASTERN WYOMING...AND WESTERN SOUTH
DAKOTA...

...SUMMARY...
Scattered severe wind gusts are expected across the northern High
Plains into tonight. Isolated large hail and severe winds gusts are
also possible over the southern High Plains.

...Northern High Plains...
Ahead of a progressive shortwave trough and associated 50-kt
midlevel jet (per VWP data), an upscale-growing cluster of
thunderstorms is advancing east-southeastward from southeast
MT/northeast WY into western SD -- with recent signs of a
rear-inflow jet. Ahead of this cluster, the UNR 00Z sounding sampled
sufficient surface-based instability and an elongated/straight
hodograph (around 40 kt of effective shear), for the maintenance of
this activity with east-southeastward extent. The primary concern
will be scattered severe wind gusts (some 75+ mph possible). See
Severe Thunderstorm Watches 487/488 and MCD 1572 for details.

...Southern High Plains...
Along the northeastern periphery of a midlevel ridge centered over
the Southwest, around 20-30 kt of midlevel northwesterly flow and
steep deep-layer lapse rates/strong buoyancy (see DDC 00Z sounding)
are supporting a few transient severe cells and clusters. Isolated
large hail and locally severe wind gusts are possible with the
stronger/more persistent storms.

...Midwest...
Scattered thunderstorms are spreading eastward along/ahead of a cold
front. While instability is marginal, enhanced low/midlevel flow
(sampled by VWP) may promote locally damaging gusts with any loosely
organized clusters that evolve.

...Coastal Carolinas...
Tropical Storm Chantal will continue tracking northward toward the
SC Coast. Locally enhanced low-level shear ahead of the storm may
promote a couple low-topped supercell structures in the outer rain
bands, with a low-end risk of a couple tornadoes.

..Weinman.. 07/06/2025


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SPC Jul 5, 2025 2000 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 2000Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0210 PM CDT Sat Jul 05 2025

Valid 052000Z - 061200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND EVENING FROM SOUTHEAST MONTANA AND NORTHEAST WYOMING INTO
WESTERN SOUTH DAKOTA...

...SUMMARY...
Scattered severe storms are likely across portions of the northern
High Plains this afternoon through the evening. Severe wind gusts
and large hail are the primary hazards.

...20z Update...
The current D1 Convective Outlook remains on track with no updates
needed. See the previous discussion below for more information.

..Thornton.. 07/05/2025

.PREV DISCUSSION... /ISSUED 1058 AM CDT Sat Jul 05 2025/

...Northern High Plains...
Morning water vapor loop shows a shortwave trough progressing into
southern ID. This feature will move across the northern Rockies,
spreading large scale forcing into much of MT this afternoon.
Scattered thunderstorms are expected to form over the mountains of
southwest MT and northern WY during the early/mid afternoon and
spread eastward into a progressively more moist/buoyant air mass.
Easterly low-level winds in the Plains, coupled with favorable
westerly flow aloft will promote supercell storm structures capable
of large hail. Most 12z CAM guidance suggests upscale growth to
bowing segments as storms track across eastern MT/WY into western
SD, with an increasing risk of significant wind damage.

...CO/KS...
Full sunshine is occurring this morning over northeast CO, leading
to afternoon temperatures in the 90s and steep low-level lapse
rates. High-based convection will form off the foothills during the
afternoon and move into this environment that will be favorable for
strong downdrafts. A consensus of morning model guidance suggests a
cluster of storms will evolve from this area, spreading eastward
into western KS this evening. Locally damaging wind gusts will be
possible. Have extended the SLGT risk southward to include this
scenario.

...SC/NC...
Tropical Storm Chantal will track northward today, approaching the
SC coast by early Sunday morning. Forecast soundings suggest that
low-level shear will steadily increase through the night along the
coast of eastern SC and southern NC. Outer rain bands associated
with the system will pose a MRGL risk of tornadoes.


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SPC Jul 5, 2025 1630 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1630Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1058 AM CDT Sat Jul 05 2025

Valid 051630Z - 061200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND EVENING FROM SOUTHEAST MONTANA AND NORTHEAST WYOMING INTO
WESTERN SOUTH DAKOTA...

...SUMMARY...
Scattered severe storms are likely across portions of the northern
High Plains this afternoon through the evening. Severe wind gusts
and large hail are the primary hazards.

...Northern High Plains...
Morning water vapor loop shows a shortwave trough progressing into
southern ID. This feature will move across the northern Rockies,
spreading large scale forcing into much of MT this afternoon.
Scattered thunderstorms are expected to form over the mountains of
southwest MT and northern WY during the early/mid afternoon and
spread eastward into a progressively more moist/buoyant air mass.
Easterly low-level winds in the Plains, coupled with favorable
westerly flow aloft will promote supercell storm structures capable
of large hail. Most 12z CAM guidance suggests upscale growth to
bowing segments as storms track across eastern MT/WY into western
SD, with an increasing risk of significant wind damage.

...CO/KS...
Full sunshine is occurring this morning over northeast CO, leading
to afternoon temperatures in the 90s and steep low-level lapse
rates. High-based convection will form off the foothills during the
afternoon and move into this environment that will be favorable for
strong downdrafts. A consensus of morning model guidance suggests a
cluster of storms will evolve from this area, spreading eastward
into western KS this evening. Locally damaging wind gusts will be
possible. Have extended the SLGT risk southward to include this
scenario.

...SC/NC...
Tropical Storm Chantal will track northward today, approaching the
SC coast by early Sunday morning. Forecast soundings suggest that
low-level shear will steadily increase through the night along the
coast of eastern SC and southern NC. Outer rain bands associated
with the system will pose a MRGL risk of tornadoes.

..Hart/Jirak.. 07/05/2025


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SPC Jul 5, 2025 1300 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0734 AM CDT Sat Jul 05 2025

Valid 051300Z - 061200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR SOUTHEAST
MONTANA INTO FAR NORTHEAST WYOMING AND EXTREME NORTHWEST SOUTH
DAKOTA...

...SUMMARY...
Scattered severe storms are likely across portions of the northern
High Plains this afternoon through the evening. Severe gusts
ranging from 60-85 mph and large to very large hail are the primary
hazards.

...Northern High Plains...
Water-vapor imagery this morning shows a mid-level trough over the
Pacific Northwest/northern Rockies. A belt of 40-50 kt 500-mb flow
will move east from ID across southern MT and northern WY through
the late evening. In the low levels, surface low pressure will
develop over central WY today to the south of a high centered over
SK/MB, aiding in maintaining an easterly component to low-level flow
across southern MT. The northern periphery of steep 700-500 mb
lapse rates will be atop a destabilizing boundary layer and will
contribute to moderate buoyancy. As large-scale ascent overspreads
south-central MT by early to mid afternoon coincident with eroding
convective inhibition, isolated to scattered thunderstorms are
forecast to develop. Ample deep-layer flow will favor a few
supercells with the early activity as storms mature/organize. An
eastward-moving cluster is forecast to evolve (supported by recent
CAM guidance) during the early evening, with a potential swath of
severe gusts focused over southeast MT into adjacent parts of WY/SD.
As storms move farther east, less buoyancy will tend to limit the
severe risk with east extent into parts of the Dakotas.

...Central-Southern High Plains...
Scattered thunderstorm development is expected this afternoon into
the evening in the vicinity of a lee trough over the central High
Plains and farther south closer to the Raton Mesa. A relatively
moist and moderately unstable airmass (~1000-2500 J/kg MLCAPE) will
support vigorous updrafts mainly in the form of multicells and small
clusters. This activity will likely spread east-southeastward into
the evening hours. Severe gusts and perhaps large hail may accompany
the more intense storms.

...Upper Midwest into the central Plains...
A separate midlevel trough will move eastward across the Upper
Midwest, while a related cold front advances southeastward across
the Upper Midwest and Lower MO Valley during the day. Despite poor
midlevel lapse rates, rich boundary-layer moisture and a belt of
enhanced low/midlevel flow will support a few strong to severe
storms capable of damaging gusts along/ahead of the front.

...Carolina coast...
The low-level wind profile is forecast to gradually strengthen
concurrent with the approach of Tropical Storm Chantal (see the
National Hurricane Center for the latest details regarding Chantal's
forecast track). By the evening, hodographs begin to substantially
enlarge near the coast and the influx of richer low-level moisture
(mid 70s F surface dewpoints) are expected to infiltrate the
immediate coast. As such, a few transient supercells are possible
with an accompanying low risk for a tornado---mainly during the
overnight.

..Smith/Broyles.. 07/05/2025


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