The Storm Prediction Center (SPC) is part of the National Weather Service (NWS) and the National Center for Environmental Prediction (NCEP). Their mission is to provide accurate forecasts and monitor the timing of thunderstorms and severe storms in the United States. The SPC provides convective outlooks on Day 1, Day 2, and Day 3 that reflect the overall level of severe weather hazard through a list of forecast statistics that identify areas at risk of mild thunderstorms and severe thunderstorms across the contiguous United State. For more information on how to read this map, please see the bottom of this page.

SPC activity loop showing a 1 hour radar loop, the current Day 1 convective outlook, and all active watches.

Convective Outlook Day 1

Convective Weather Outlook Day 1

SPC Day 1 Outlook Discussion

ACUS01 KWNS 180549
SWODY1
SPC AC 180548

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1248 AM CDT Mon Aug 18 2025

Valid 181200Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE CENTRAL HIGH PLAINS...

...SUMMARY...
Strong to severe storms capable of damaging winds are possible in
parts of the Upper Midwest today. Isolated to widely scattered
storms with large hail and severe winds are possible in parts of the
central/northern Plains through tonight.

...Central High Plains...
A broad upper trough over the northern Plains will move east today
with an attendant surface low and cold front also moving east.
Behind the departing surface low, weak upslope flow is expected
across portions of western SD, northeastern WY. Strong heating and
steep mid-level lapse rates should allow for diurnal destabilization
with widely scattered thunderstorms expected along a lee trough by
the afternoon. Elongated hodographs, courtesy of 30-40 kt of
westerly flow aloft, will allow for some organized storms including
supercells or clusters. Steep mid-level lapse rates, and moderate
buoyancy will support a hail risk. 

Farther south, stronger heating and mixing will limit low-level
moisture across southeastern WY and northeastern CO. Still, enough
CAPE should be present for scattered high-based storms near peak
heating. The steep low-level lapse rates and any clustering that
develops should support damaging winds as storms spread eastward
into northeast CO and western NE.

Some potential exists for a longer-lived cluster to spread eastward
into central/eastern NE and northern KS overnight. Should this
occur, damaging winds and some hail would be the primary concerns,
though this scenario remains highly uncertain given weaker forecast
low-level jet.

...Midwest...
One or more clusters of thunderstorms or an MCV is expected to be
ongoing at the start of the period in the vicinity of the warm front
across portions of IA/MN, casting significant uncertainty on the
overall convective evolution for the day. Filtered diurnal heating
and nebulous ascent from the broad trough over the northern Plains
could support continuation of these storms and additional
development into southern WI and northern IL this afternoon. While
complications abound, substantial buoyancy (3000-4000 J/kg of
MLCAPE) and dewpoints in the mid 70s F south of the composite
front/remnant outflow will be supportive of occasional vigorous
updrafts. Modest enhancement of the mid and upper-level flow could
support a few semi-organized clusters or transient supercells with
damaging wind potential. Given the potential for outflow or
thunderstorm clusters to significantly alter the environment,
confidence in higher wind probabilities is low.

...Southwest into central Montana...
Despite a strong ridge building into the northern Rockies,
sufficient moisture may promote thunderstorm development in the
higher terrain this afternoon. 20-30 kt of flow aloft will be
sufficient to support at least marginally organized storms. However,
strong mixing during the afternoon could limit buoyancy and storm
coverage. Occasional strong, gusty outflow winds are possible with
any high-based storms, but confidence in severe potential remains
low.

..Lyons/Kerr.. 08/18/2025

$$


Convective Outlook Day 2

Convective Weather Outlook Day 2

SPC Day 2 Outlook Discussion

ACUS02 KWNS 180555
SWODY2
SPC AC 180553

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1253 AM CDT Mon Aug 18 2025

Valid 191200Z - 201200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
A severe threat is not expected across the continental U.S. on
Tuesday or Tuesday night.

...DISCUSSION...
A mid-level ridge will build northward across the central Rockies
and northern High Plains on Tuesday, as a subtle shortwave trough
moves through the Great Lakes region. At the surface, a cold front
will advance southward into the Ohio and mid Mississippi Valleys,
extending westward into the southern Plains. As surface temperatures
warm during the day, low-level convergence near the front will be
favorable for isolated to scattered thunderstorm development.
Limited large-scale ascent and weak deep-layer shear will be
unfavorable for severe storms. Further northwest into the
north-central states, moderate instability will be possible by
Tuesday afternoon, mainly in the Dakotas. However, a severe threat
is not expected due to limited large-scale ascent, minimal low-level
convergence, and weak deep-layer shear. Elsewhere across the
continental U.S., a severe threat is not expected Tuesday and
Tuesday night.

..Broyles.. 08/18/2025

$$


Convective Outlook Day 3

Convective Weather Outlook Day 3

SPC Day 3 Outlook Discussion

ACUS03 KWNS 180714
SWODY3
SPC AC 180713

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0213 AM CDT Mon Aug 18 2025

Valid 201200Z - 211200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
No severe threat is expected across the continental U.S. on
Wednesday or Wednesday night.

...DISCUSSION...
A large area of mid-level high pressure will remain over the
Intermountain West and Rockies on Wednesday, as an associated ridge
moves eastward across the northern Plains. At the surface, a moist
airmass will be in place over much of the eastern two-thirds of the
nation. In spite of this, convective development will be isolated
over much of this airmass during the day on Tuesday. The greatest
convective coverage is expected near a front from the southern
Plains east-northeastward into the southern Appalachians Wednesday
afternoon. Within this corridor, deep-layer shear and large-scale
ascent will remain weak, suggesting that conditions will not be
favorable for severe storms. Further to the east, Hurricane Erin is
expected to remain in the far western Atlantic, and convective
potential is expected to be minimal along the Atlantic Seaboard.
Elsewhere, a severe threat is not expected to develop across the
continental U.S. Wednesday or Wednesday night.

..Broyles.. 08/18/2025

$$


Convective Outlook Day 4-8

Convective Weather Outlook Day 4-8

SPC Day 4-8 Outlook Discussion

ACUS48 KWNS 170855
SWOD48
SPC AC 170854

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0354 AM CDT Sun Aug 17 2025

Valid 201200Z - 251200Z

...DISCUSSION...
...Wednesday/Day 4 to Friday/Day 6...
On Wednesday, a mid-level ridge will likely be in place across the
northern Plains. At the surface, a front is forecast to be located
over the Ozarks and lower Ohio Valley. Moderate instability is
expected to develop to the south of the front, and over parts of the
north-central states. In areas where storms are expected, deep-layer
shear should be weak, suggesting a severe threat is unlikely.

On Thursday, a mid-level shortwave trough and an associated cold
front are forecast to move eastward into the northern Plains. An
axis of moderate instability is forecast ahead of the front. This
combined with moderate deep-layer shear could be enough for an
isolated severe threat during the afternoon and evening, mainly over
eastern North Dakota and northwestern Minnesota.

The front and its associated shortwave trough are forecast to move
into the upper Mississippi and mid Missouri Valleys on Friday.
Moderate instability appears likely to develop ahead of the front
during the afternoon. Along and near the instability axis, the
greatest potential for thunderstorm development could occur in the
central Plains within northwest mid-level flow. An isolated severe
threat will be possible during the late afternoon and early evening.

...Saturday/Day 7 and Sunday/Day 8...
On Saturday and Sunday, an upper-level trough is forecast to remain
over the Great Lakes region. Ahead of the trough, an axis of
instability is forecast to develop in the central Appalachians,
where isolated to scattered thunderstorms will be possible each
afternoon. Moderate deep-layer shear could be sufficient for an
isolated wind-damage threat, mainly in the late afternoon as
low-level lapse rates become steep.

..Broyles.. 08/17/2025


Convective Weather Outlook Legend Data

  • TSTM (light green) – General or non-severe thunderstorms – Delineates, to the right of a line, where a 10% or greater probability of thunderstorms is forecast during the valid period.
  • 1-MRGL (dark green) – Marginal risk – An area of severe storms of either limited organization and longevity, or very low coverage and marginal intensity.
  • 2-SLGT (yellow) – Slight risk – An area of organized severe storms, which is not widespread in coverage with varying levels of intensity.
  • 3-ENH (orange) – Enhanced risk – An area of greater (relative to Slight risk) severe storm coverage with varying levels of intensity.
  • 4-MDT (red) – Moderate risk – An area where widespread severe weather with several tornadoes and/or numerous severe thunderstorms is likely, some of which should be intense. This risk is usually reserved for days with several supercells producing intense tornadoes and/or very large hail, or an intense squall line with widespread damaging winds.
  • 5-HIGH (magenta) – High risk – An area where a severe weather outbreak is expected from either numerous intense and long-tracked tornadoes or a long-lived derecho-producing thunderstorm complex that produces hurricane-force wind gusts and widespread damage. This risk is reserved for when high confidence exists in widespread coverage of severe weather with embedded instances of extreme severe (i.e., violent tornadoes or very damaging convective wind events).

This data is courtesy from the Storm Prediction Center