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.
Convective Outlook Day 1
SPC Day 1 Outlook Discussion
ACUS01 KWNS 100049 SWODY1 SPC AC 100048 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0748 PM CDT Wed Jul 09 2025 Valid 100100Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TONIGHT ACROSS PARTS OF THE EASTERN DAKOTAS...CENTRAL AND EASTERN NEBRASKA...SOUTHWESTERN MINNESOTA AND WESTERN IOWA... ...SUMMARY... Scattered strong thunderstorm development, perhaps including an organizing cluster or two, remains possible tonight and could pose a risk for severe wind and hail across the northern Great Plains/Mid Missouri Valley vicinity. ...01Z Update... ...Northern Great Plains/Mid Missouri Valley... Scattered, generally high-based strong thunderstorm development, which initiated within lee surface troughing across the northern high plains, has slowly propagated into the central Dakotas and Nebraska, in the presence of at least modestly sheared, but weak (10-20 kt) westerly deep-layer mean flow. Seasonably moist boundary-layer air (including 70+ F surface dew points) along a baroclinic zone across the central into eastern Dakotas and Nebraska is contributing to a corridor of moderate to strong potential instability, beneath steep lower/mid-tropospheric lapse rates. However, the thermodynamic profiles include very warm elevated mixed-layer air (including 700 mb temperatures of +12 to 14 C), which will contribute to increasingly substantive inhibition with the onset of boundary-layer cooling. It remains unclear how long forcing for ascent will be sufficient to maintain ongoing convective development this evening, but a nocturnally strengthening low-level jet, aided by boundary-layer decoupling, is forecast across western Kansas toward the mid Missouri Valley through 03-06Z. This would seem to offer better potential for the maintenance and perhaps intensification of the cluster now propagating south/southeast of Valentine NE. Otherwise, warm advection aided by the low-level jet could focus renewed thunderstorm initiation and upscale growth on the eastern periphery of the more strongly capping elevated mixed-layer air, across the southeastern South Dakota/eastern Nebraska/western Iowa vicinity later tonight. ..Kerr.. 07/10/2025 $$ |
Convective Outlook Day 2
SPC Day 2 Outlook Discussion
ACUS02 KWNS 091726 SWODY2 SPC AC 091724 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1224 PM CDT Wed Jul 09 2025 Valid 101200Z - 111200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN THE CENTRAL GREAT PLAINS AND THE SOUTHEAST... ...SUMMARY... A corridor of scattered damaging winds is possible Thursday afternoon across a portion of the Southeast. Scattered severe thunderstorms are possible over parts of the central Great Plains, mainly from late afternoon through Thursday night. ...Central States... Much uncertainty plagues this forecast cycle with low predictability across guidance related to the development/evolution of multiple MCVs from D1. These MCVs will meander downstream of a low-amplitude shortwave trough progressing east from the northeast Great Basin into the central Great Plains on D2. Meanwhile, a positive-tilt shortwave trough should amplify from the Canadian Rockies into the southern Prairie Provinces/northern High Plains by early Friday. Have expanded level 1-MRGL risk eastward across the Upper MS Valley for potential diurnal intensification of convection surrounding remnant MCVs. While confidence is quite low in spatiotemporal details and the degree of convective coverage, there is adequate signal across guidance to warrant low-probability severe hail/wind hazards. Primary severe potential will likely commence towards peak heating across the central High Plains ahead of the aforementioned low-amplitude shortwave trough. Hot/deep-mixed thermodynamic profiles are expected from southwest/south-central NE southward, as the dryline reaches central KS. High-based convection in the post-dryline airmass will offer a threat of sporadic severe gusts. As convection impinges on a more buoyant airmass downstream, in tandem with a strengthening low-level jet from the southern High Plains towards eastern NE, an MCS should develop over NE in the evening. A downstream warm-advection arc will aid in sustaining this MCS eastward across a portion of the Mid-MO Valley. A swath of severe wind gusts with embedded severe hail will be possible Thursday night. Farther north in the northern Great Plains, latest signals are for broad, low-probability hail/wind threats. The timing of ascent and strengthening mid/upper-level flow appears delayed until late in the period ahead of the Canadian Rockies/northern High Plains trough. Convective coverage should remain isolated during the late afternoon to early evening along a weak surface front/trough. Modest deep-layer shear during this timeframe will modulate the overall threat as well. Greater convective potential should exist overnight but may largely remain behind the undercutting surface front as it sharpens southeastward. ...East... Weak deep-layer shear will be prevalent across much of the region on Thursday afternoon, south of modest mid-level westerlies across NY/New England associated with a low-amplitude shortwave trough over southeast Canada. Rich boundary-layer moisture will remain prevalent from the DE Valley southward. This will support a primary threat of wet microbursts producing erratic damaging winds. Have maintained a level 2-SLGT risk in a portion of the Southeast for the most probable corridor of widespread thunderstorms producing localized damaging winds. ..Grams.. 07/09/2025 $$ |
Convective Outlook Day 3
SPC Day 3 Outlook Discussion
ACUS03 KWNS 091928 SWODY3 SPC AC 091927 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0227 PM CDT Wed Jul 09 2025 Valid 111200Z - 121200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN CENTRAL KS TO EASTERN IA... ...SUMMARY... Scattered severe thunderstorms are possible, mainly late afternoon and evening on Friday, from central Kansas to eastern Iowa. ...Central States... Primary change this outlook is to add a level 2-SLGT risk for the most probable corridor of severe storms during the late afternoon and evening Friday. Have also expanded the longitudinal extent of the level 1-MRGL in the North-Central States and southward through the southern High Plains. A decaying MCS should be ongoing at 12Z Friday in vicinity of IA. An attendant MCV with this activity may be separate from the mid-level impulse/low-amplitude shortwave trough that is progged to emerge onto the central Great Plains Thursday night. A belt of modestly enhanced mid-level west-southwesterlies ahead of these features will support semi-organized clustering as renewed convective development occurs towards peak heating. This is anticipated from along a retreating large-scale outflow boundary southwestward towards the dryline mixing into central KS. With ample buoyancy, scattered severe storms seem possible with damaging wind as the main hazard. Isolated severe storms are possible across a much broader region. Along the synoptic cold front in northern MN to eastern SD, mid-level flow enhancement should be confined west of the front, owing to the positive-tilt orientation and compact nature of the shortwave trough across the southern Canadian Prairies into the northern Great Plains. Modest mid-level northwesterlies will support an isolated severe threat across the central/southern High Plains, with high-based convection in a limited buoyancy environment. ...East... A low-amplitude mid-level trough will move east from QC to the Canadian Maritimes. Weak height rises will occur in its wake across New England. Still, most guidance suggests isolated thunderstorms will be possible in this region, where moderate effective bulk shear could support an isolated/marginal wind/hail threat Friday afternoon. Farther south, scattered thunderstorms seem probable Friday afternoon from the DE to Savannah Valleys. Prior days of extensive convective overturning should temper PW values/storm coverage to an extent. This suggests wet microburst potential may be subdued. ..Grams.. 07/09/2025 $$ |
Convective Outlook Day 4-8
SPC Day 4-8 Outlook Discussion
ACUS48 KWNS 090820 SWOD48 SPC AC 090818 Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0318 AM CDT Wed Jul 09 2025 Valid 121200Z - 171200Z ...DISCUSSION... The overall large-scale pattern looks to remain characterized by mid-to-upper-level ridging across the western United States with a zonal to broadly cyclonic flow across the northern tier of the US through the forecast period. At the same time, rich/moist low-level moisture looks to remain entrenched across much of the eastern US, sustained in part by broad, southerly flow, albeit with some fluctuations in raw values. Global models continue to be bullish on a seasonably strong cold front pushing south through much of the central US late in the forecast period, ushering in a cooler/drier airmass. Strong-to-locally severe thunderstorms will be possible somewhere across the eastern CONUS every day of the forecast period. However, with synoptic-scale forcing/dynamics primarily constrained to Canada, most thunderstorms will be determined by sub-synoptic/mesoscale details dictated by/reinforced with each prior day's convection. Thus, confidence is too low in any one location on any given day to introduce unconditional severe probabilities at this time. However, some areas/scenarios of interest to monitor include the southern Great Plains on Days 4-5/Saturday-Sunday as a moist, weakly capped environment will exist in proximity to an increasing diffuse surface boundary. Other areas include the East Coast most afternoons and the along and ahead of seasonably strong cold front pushing south through the Great Plains from Days 6-8. For each of the areas of interest/scenarios of interest above, weak effective-layer shear stemming from generally weak tropospheric flow will be a limiting factor for a more organized severe potential and confidence to introduce unconditional probabilities. ..Marsh.. 07/09/2025
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-MDTÂ (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