The Storm Prediction Center convective weather outlook 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 outlooks through a list of forecast statistics. This data identifies areas at risk of mild thunderstorms and severe thunderstorms. For more information on how to read this map, please see the bottom of this page.
Convective Outlook Day 1
SPC Day 1 Outlook Discussion
ACUS01 KWNS 300556 SWODY1 SPC AC 300555 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Tue Jun 30 2026 Valid 301200Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS NORTHERN WISCONSIN AND THE UPPER PENINSULA OF MICHIGAN...PARTS OF NEW YORK AND VERMONT...AND PORTIONS OF THE CENTRAL/SOUTHERN PLAINS...... ...SUMMARY... Severe thunderstorms will be possible from parts of the central High Plains into the Upper Midwest, and across parts of the Northeast on today. ...Synopsis... An upper-level low will move into Saskatchewan/Manitoba today, with west southwesterly flow aloft overspreading portions of northern Minnesota into northern Wisconsin and the Upper Peninsula of Michigan. A frontal boundary will extend from a surface low across Manitoba southward across the Upper Midwest into the Central Plains, with a dryline extending southward into the Southern Plains. Across the Northeast, enhanced northwesterly flow aloft will impinge upon the northeastern periphery of a high amplitude ridge across the eastern US. ...Upper Midwest/Great Lakes... A southwesterly low-level jet is set to increase across central/northern Wisconsin by late afternoon. This in combination with forcing for ascent from the upper-level trough should support convection developing near the surface boundary across northern Wisconsin into the Upper Peninsula of Michigan. To the south/east of the boundary, a very moist air mass with 70s dewpoints is forecast. Strong to extreme instability is forecast across this region amid strong deep layer shear profiles, supporting initial supercells capable of large hail, damaging wind, and perhaps a tornado. With time, clustering may support potential for an increase in damaging wind potential. Guidance also suggests further development may occur by late evening across portions of Nebraska into northern Iowa as the surface boundary begins to shift northward with a short-wave impulse rotating through the upper trough. This will pose some potential for damaging wind and hail through the late evening/overnight period. Forecast soundings suggests this activity may remain elevated, leading to lower confidence in higher probabilities. ...Northeast... A belt of 45 kt northwesterly flow aloft will overspread portions of the Northeast this afternoon. Guidance suggests that thunderstorms will develop across the region by the afternoon. Deep layer shear around 35-40 kts and moderate instability thunderstorm development is forecast across the region. This will support transient supercells before one or more clusters/bowing segments develop and spread south and eastward with damaging wind potential. A stronger supercell or two may be capable of a tornado or two. ...Southern/Central High Plains... A mid-level shortwave will eject across the central Plains this afternoon, with widely scattered thunderstorm development expected near the surface trough/dryline in the afternoon/evening. A southerly low-level jet is progged to increase across the area through the evening. Moderate to strong instability is progged amid steep low to mid-level lapse rates. Initial high-based convection will pose potential for large hail and damaging wind. With clustering/consolidation along outflows, the damaging wind threat will increase with potential for instances of significant winds 70-80 mph. ...Southeastern US... Forecast guidance depicts 25-35 kt mid-level northeasterly flow on the southern periphery of an upper high centered over the OH/TN Valley. A very moist air mass will be present across much of the region and strong destabilization is forecast amid strong daytime heating. Forecast soundings depict around 20-30 kt effective shear magnitudes, supporting some risk of organized cells/clusters. Isolated damaging wind gusts are possible as activity develops west/southwest through early evening. ..Thornton/Chalmers.. 06/30/2026 $$ |
Convective Outlook Day 2
SPC Day 2 Outlook Discussion
ACUS02 KWNS 300608 SWODY2 SPC AC 300607 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0107 AM CDT Tue Jun 30 2026 Valid 011200Z - 021200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE MID-MISSOURI VALLEY INTO CENTRAL WISCONSIN... ...SUMMARY... Isolated to scattered strong to severe storms will again be possible from the central Plains into the Upper Midwest as well the Northeast on Wednesday. Severe wind gusts and large hail are the main concerns. ...Mid-Missouri Valley into central Wisconsin... Models are in general agreement that a cluster/MCS will be ongoing in the eastern South Dakota/southern Minnesota vicinity early Wednesday morning. There is at least some potential for damaging surface gusts with this activity. Further intensification could also occur as the airmass destabilizes in parts of Wisconsin into the afternoon. However the early day activity evolves, an outflow boundary from this activity will serve as a focus for additional afternoon thunderstorms. 70+ F dewpoints to the south of the boundary will again promote strong to locally extreme buoyancy. Moderate to strong mid-level winds on the southern flank of the upper trough in Canada will allow for 40-55 kt of effective shear near the surface boundary. Initial supercells will be capable of large to isolated very large (around 2-2.5 in.) hail and perhaps a tornado or two. Given the instability, strong downdrafts will likely lead to upscale growth relatively quickly. The risk for severe/damaging winds will become the primary hazard with time, particularly if an MCS can develop. A Slight Risk has been added to cover both potential scenarios. ...Northeast... The forecast continues to be uncertain given the nebulous forcing for ascent. Nonetheless, substantial buoyancy will be in place across the region (3000-5000 J/kg MLCAPE). Effective shear of 35-40 kt will promote some storm organization. Model guidance shows variable solutions from more isolated cellular activity to a cluster moving southeastward out of Canada. Given the low confidence in placing more organized activity, a Marginal Risk will be maintained for now. Damaging winds and isolated large hail will be possible. ...Central High Plains... Thunderstorm development is expected within the lee trough during the afternoon. A deeply-mixed boundary layer will promote potential for severe winds especially if any clustering can occur. Shear will be modest and severe coverage is expected to be isolated. ...Southeast... Strong buoyancy will be in place during the afternoon given rich moisture (70+ F dewpoints). Shear will be quite weak with some minor enhancement in the lower Mississippi Valley. Models do show some potential for clustering, but the location is quite variable. Lack of even subtle features to focus convection keeps confidence in a more organized damaging wind threat low. ..Wendt.. 06/30/2026 $$ |
Convective Outlook Day 3
SPC Day 3 Outlook Discussion
ACUS03 KWNS 291900 SWODY3 SPC AC 291900 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0200 PM CDT Mon Jun 29 2026 Valid 011200Z - 021200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL PLAINS TO THE UPPER MIDWEST/GREAT LAKES...AND ACROSS THE NORTHEAST... ...SUMMARY... Isolated strong to severe storms will again be possible from the central Plains into the Upper Midwest as well the Northeast on Wednesday. Severe wind gusts and large hail are the main concerns. ...Synopsis... The overall synoptic pattern will not changes much from Day 2/Tuesday into Day 3/Wednesday. The upper ridge over the eastern U.S. may shift slightly east while an upper trough persists over the West. A series of midlevel shortwave impulses will migrate across the northern Plains and Upper Midwest/Great Lakes vicinity. Enhanced mid/upper flow will persist from the Dakotas into the Great Lakes and over the Northeast. ...Upper Midwest/Great Lakes... A quasi-stationary boundary is forecast to extend from northern WI toward southeast SD Wednesday morning. This boundary may slowly lift northward during the afternoon. The evolution of this boundary will largely be influenced by morning convection that may be ongoing near/north of the boundary across parts of MN/WI at the beginning of the period. Given a very moist airmass, strong to extreme instability is forecast near and south of the boundary. Morning convection could weaken as it lifts north of the boundary, or it could intensify through the day as destabilization occurs, spreading east across the Upper Great Lakes. Another round of convection may develop during the late afternoon into the nighttime hours along the boundary as well. While convective evolution is uncertain, the thermodynamic and kinematic parameter space will support a risk for severe wind gusts and large hail. Enhanced low-level shear near the surface boundary could also result in a corridor of tornado potential. Higher severe probabilities will likely be needed in subsequent outlooks as mesoscale details and convective evolution become more clear and forecast confidence increases. ...Northeast... Large-scale ascent will not be as strong across the region on Wednesday, though forecast guidance does show a shortwave impulse or MCV moving across the area as it crosses the international border from Canada. A very moist and strongly unstable airmass will be in place and strengthening mid/upper northwesterly flow will support some organized severe risk. However, storm coverage remains uncertain. Strong downburst winds and isolated large hail will be possible. The wind risk could increase if sufficient storm coverage/interaction results in clustering/bowing segments, but this scenario is uncertain given a lack of stronger low-level jet. Trends will be monitored and higher severe probabilities may be needed in subsequent outlooks. ...Central High Plains... A surface trough will extend southward from western SD/NE into eastern CO/NM on Wednesday. Southerly low-level flow will maintain modest boundary layer moisture beneath steep midlevel lapse rates. Southerly flow through around 500 mb will be somewhat weak, though southwesterly flow increases substantially above that. This could be sufficient for weakly organized convection developing within upslope flow along the surface trough Wednesday afternoon/evening. Given weaker instability and more modest vertical shear compared to previous days, severe potential is more uncertain. However, strong outflow gusts still appear possible given a deeply mixed boundary layer and inverted-v sub-cloud thermodynamic profiles. ...Southeast... Isolated to scattered thunderstorms are likely to develop on the southern periphery of the upper anticyclone Wednesday afternoon. A very moist and strongly unstable airmass will be in place, but vertical shear appears a bit weaker compared to Day 2/Tuesday. Storm coverage is uncertain, but some risk for locally strong gusts may develop, especially if sufficient clustering can occur to promote forward propagation. ..Leitman.. 06/29/2026 $$ |
Convective Outlook Day 4-8
SPC Day 4-8 Outlook Discussion
ACUS48 KWNS 290901 SWOD48 SPC AC 290859 Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0359 AM CDT Mon Jun 29 2026 Valid 021200Z - 071200Z ...DISCUSSION... The broad trough in the West and ridge in the East will persist through the remainder of the week. A moist airmass across much of the CONUS east of the Rockies will support repeated days of convective activity. Large-scale forcing will remain weak, but shortwave troughs emanating from the western trough will promote development within the Plains and the Upper Midwest where a stalled surface boundary will be positioned. Both Thursday and Friday show potential for MCS development from Nebraska into the Dakotas. Friday will likely have a more prominent shortwave trough as a lifting mechanism. Where this potential severe weather will be focused is not certain given the expected convection that will occur each day prior. For Saturday, some models show the shortwave trough moving into the Upper Midwest where another round of convection may occur. Severe probabilities are certainly possible in the coming days as confidence continues to increase. Another area to watch this week will be the Northeast. Here, stronger northwesterly flow at mid levels will continue into part of the weekend. Depending on how the shortwave trough evolves in the Upper Midwest, this feature may eventually move into the Northeast and promote thunderstorm development late this weekend into next week. Predictability remains too low for highlights, however. ..Wendt.. 06/29/2026
Convective Weather Outlook Legend Data
- TSTMÂ (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-ENHÂ (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. Also, 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