SEVERE WEATHER OUTLOOK
Day 1 Convective Outlook
Forecast Discussion
SPC AC 231959 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Sun Aug 23 2026 Valid 232000Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN ROCKIES/PLAINS AND GREAT BASIN... ...SUMMARY... Thunderstorms capable of producing large hail and severe wind gusts are forecast across parts of the northern Rockies/Plains this afternoon and evening. Other thunderstorms with mainly a severe wind threat are probable over portions of the northern Great Basin. ...20z Update... ...Northern Rockies/Plains and Great Basin... Subtle adjustments were made to the existing Marginal/Slight risk areas based on ongoing convective trends. Recent CAM/TLE guidance suggests that upscale growth of convection into one or more linear clusters may result in localized corridors of greater damaging/severe wind coverage across portions of northern Utah and central Montana. The evolution of this scenario remains somewhat uncertain, however, which precludes the addition of 30% wind probabilities at this time. See MCDs 2099, 2100, and 2101 for additional short-term details. ...Coastal Carolinas... Recent mesoanalysis and observational data depict modestly elongated hodographs and effective shear around 35 kts in place across portions of the Coastal Carolinas. Despite poor mid-level lapse rates, this may allow for the occurrence of isolated, marginally severe hail with the most robust updraft cores. Thus, a targeted 5% hail probability area was included with this update, which is similarly supported by AI/ML guidance and recent CAM solutions. Elsewhere, the forecast remains largely on track, with only minor adjustments made based on the latest forecast and observational trends. See the discussion below for additional details. ..Chalmers/Moore.. 08/23/2026 .PREV DISCUSSION... /ISSUED 1135 AM CDT Sun Aug 23 2026/ ...Great Basin into the Northern Rockies/High Plains... Water-vapor imagery this morning shows an eastward-migrating shortwave trough over the Pacific Northwest. A belt of 40-50 kt of west-southwesterly mid-level flow will overspread the northern Rockies and adjacent High Plains of central/eastern MT by this afternoon. Heating along with ascent attendant to the disturbance will favor initial storm development over the higher terrain over southwest/western MT. Steepening lapse rates over the High Plains will favor the potential for scattered severe gusts as thunderstorms move/develop over the plains during the late afternoon and evening. A mix of multicells and supercells may yield a risk for severe hail early before upscale growth into linear clusters (60-80 mph gusts) likely evolves during the evening. A somewhat separate area of convection should develop this afternoon across parts of the northern Great Basin and Upper Snake Valley. While mid-level flow will be somewhat weaker across this region compared to locations farther north, the presence of generally 50s surface dewpoints across northern UT and vicinity suggests that sufficient low-level moisture exists to support robust updrafts. Very steep lapse rates will favor ample evaporative cooling in the stronger downdrafts. Scattered severe gusts (60-80 mph) are possible with the stronger thunderstorm cores and outflow. ...Northern/Central Plains... Morning surface analysis places a moisture plume (lower to mid 60s deg F dewpoints) extending from the TX-OK Panhandles north-northwestward through eastern CO/NE Panhandle and into the Black Hills vicinity. It is within this corridor moderate to strong instability is forecast by mid-late afternoon along/east of a lee surface trough. At least isolated thunderstorms should develop by peak afternoon heating across these areas, with west-northwesterly flow strengthening with height through mid/upper levels. Around 35-45 kt of deep-layer shear will support supercells and associated threat for large hail from northeast CO northward into the western Dakotas. Farther south, high-based convection is forecast to slowly spread/move east of the Raton Mesa into the TX-OK Panhandles during the early evening. Very steep lapse rates and inverted-V profiles will favor evaporative cooling and an isolated threat for severe gusts with the stronger downdrafts and outflow surges. ...Northeast... Midday satellite imagery shows an upper trough/low over Ontario with a series of embedded shortwave impulses rotating through its base. A lead disturbance over the Lower Great Lakes will continue to rotate northeastward across the western portion of the Northeast and influence scattered thunderstorm development this afternoon. Heating of an adequately moist airmass but relatively meager mid-level lapse rate environment will result in weak buoyancy developing through mid afternoon as convection deepens. Around 30-35 kt of deep-layer shear will support some updraft organization mainly in the form of bands of storms. An isolated risk for strong to locally severe gusts is expected across much of this region this afternoon. Towards early evening, an upstream impulse will approach the Lake Erie vicinity with some uptick in storm coverage and perhaps a lingering risk for wind damage before this activity weakens by the mid evening. ...Southeast... Isolated to scattered thunderstorms will likely develop along/south of a weak front draped across the lower MS Valley into the Gulf Coast states, and continuing northeastward into the Carolinas. An isolated threat for strong to locally severe gusts may result in pockets of wind damage with the more intense wet microbursts. ...Northeast Oklahoma/Southeast Kansas into the Ozarks... Some modest increase in isentropic ascent associated with a south-southwesterly low-level jet, may aid thunderstorm development late tonight into early Monday morning across parts of northeast OK/southeast KS into the Ozarks. Instability is forecast to remain fairly weak (MUCAPE generally less than 1000 J/kg), but some clustering may occur with a low chance for localized severe gusts. ...Arizona... On the western periphery of a mid-level anticyclone centered over eastern NM, weak southeasterly mid-level flow will remain across southern/central AZ. Model guidance only depicts weak buoyancy across much of central and southern AZ, with the exception of perhaps over far southern AZ. Nonetheless, hot temperatures and a deeply mixed boundary layer lend some potential for a localized microburst risk. NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
Updated: Sun Aug 23 19:59:36 UTC 2026 (
Day 2 Convective Outlook
Forecast Discussion
SPC AC 231728 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1228 PM CDT Sun Aug 23 2026 Valid 241200Z - 251200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE CENTRAL HIGH PLAINS AND THE LOWER MISSISSIPPI VALLEY... ...SUMMARY... Thunderstorms producing scattered severe gusts appear likely across the central High Plains and Lower Mississippi Valley tomorrow (Monday). Isolated severe thunderstorms, posing mainly a damaging/severe gust or sparse hail threat, may also occur across parts of the Northern Great Basin into the southern High Plains, the Gulf to Carolina Coastline, and Maine. ...Synopsis... Upper ridging will persist across the western and central U.S. as an upper trough is poised to traverse the Northeast and impinge on the Atlantic tomorrow (Monday). A pronounced mid-level shortwave trough will crest the ridge and eject into the northern Plains by tomorrow afternoon, encouraging surface lee troughing along the central High Plains to the U.S./Canada border. Adequate low-level moisture advection northward across the Plains, beneath seasonably cooler temperatures aloft, in conjunction with stronger mid-level flow (and thus vertical wind shear), will encourage strong to severe thunderstorm potential over the northern Plains. Meanwhile, some severe threat may exist with storms across the northern Great Basin, Maine, and parts of the Gulf coastline. ...Northern Plains to the central High Plains... Isolated to widely scattered thunderstorms are expected develop ahead of a surface lee trough from the Canadian border to the southern High Plains tomorrow afternoon. Mid to upper flow will be strongest across the northern High Plains into the northern Plains, where 30-40 kts of westerly 500 mb flow will support similar values of effective bulk shear. The latest high-resolution guidance consensus depicts a higher density cluster of multicells and perhaps supercells developing somewhere around the Black Hills of SD and propagating south-southeastward into NE. Given merging cold pools, scattered severe gusts are possible, along with a couple instances of severe hail. Closer to the Canadian border, convective coverage is less certain, though 2000-3000 J/kg MLCAPE and modestly curved/elongated forecast hodographs suggest supercell potential exists in this area. An upgrade to a Slight Risk may be needed pending guidance trends involving greater storm coverage. Tropospheric flow across the southern to central High Plains will be weaker compared to points farther north. However, the presence of a dry boundary layer extending upward to at least 700 mb, amid 1000+ J/kg MLCAPE, should support some risk for dry downbursts with the stronger storm cores, perhaps accompanied by an isolated severe gust threat. ...Portions of the northern Great Basin to the central Rockies... By afternoon peak heating, scattered high-based thunderstorms should develop amid classic inverted-V profiles. Since these storms will develop along the periphery of stronger flow aloft (driven by a departing mid-level shortwave trough), some organization is possible. Multiple dry microbursts may occur, some of which may pose a severe gust threat. An upgrade to a Slight Risk may be needed if guidance consensus trends upward in convective coverage. ...Maine... By late morning into early afternoon, partially clearing skies will encourage surface temperatures to rise into the 70s F, resulting in marginal instability (e.g. a few hundred J/kg MLCAPE) given relatively poor mid-level lapse rates. Nonetheless, a southerly mid- to upper-level jet streak will overspread northern New England during the afternoon, resulting in highly elongated hodographs and 30-40 kts of effective bulk (speed) shear. As such, any storms that can develop and become sustained should become organized multicells capable of supporting a few damaging gusts. ...Portions of the Gulf to Carolina coastlines... By late morning into the afternoon, the heating of a very moist boundary layer (e.g. 70s F surface dewpoints) will yield 2000-4000 J/kg MLCAPE, despite poor mid-level lapse rates. Once convective temperatures are reached, several pulse storms and multicells will develop, capable of producing wet downbursts and at least isolated damaging gusts. Vertical wind shear will be locally stronger along the NC coastline, where a supercell cannot be ruled out. A consensus among CAMS depicts a relatively more organized cluster of multicells emanating from a warm-air-advection regime across the Ozark Valley, which will mature over southern MS into LA. Here, there may be a locally denser cluster of damaging gusts, hence the introduction of Category 2/Slight Risk severe wind probabilities. ..Squitieri.. 08/23/2026 NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z
Updated: Sun Aug 23 17:28:32 UTC 2026 (
Day 3 Convective Outlook
Forecast Discussion
SPC AC 231930 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 PM CDT Sun Aug 23 2026 Valid 251200Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL AND SOUTHERN HIGH PLAINS... ...SUMMARY... At least widely scattered severe storms are likely across portions of the central Plains on Tuesday. More isolated severe storms may also occur across parts of the Southeast and the Upper Mississippi Valley. ...Synopsis... A synoptic scale mid-level anticyclone will overspread most of the western and central CONUS on Tuesday, with multiple mid-level impulses poised to pivot around the anticyclone across the Plains states into the Upper- and Mid-MS Valleys. The most pronounced impulse, in the form of a mid-level shortwave trough, will traverse the northern Plains Tuesday afternoon, supporting a surface trough with a cold front draping southwestward across the Plains. Along and ahead of the cold front, enough deep-layer shear and ascent, in tandem with adequate buoyancy, will support at least scattered severe storms across the southern and central High Plains into the Upper MS Valley. ...Central and southern High Plains... As a mid-level impulse crests the ridge and tracks southeastward across the northern Plains, a cold front will drift south-southeastward across NE. Meanwhile, upslope moist low-level flow will encourage both increased instability and convergence along the immediate lee of the Rockies over NM and CO. 8 C/km mid-level lapse rates will overspread 60s F surface dewpoints, yielding 2000-4000 J/kg MLCAPE, with the strongest buoyancy expected immediately ahead of the cold front over northeast CO into NE. Here, the greatest severe threat exists since 40 kts of effective bulks shear will also coincide with the aforementioned buoyancy, with severe wind- and hail-producing multicells and supercells expected. There is some indication for the potential of cold-pool mergers and subsequent development of an MCS. If this occurs, a severe wind swath would manifest across the central High Plains. Farther south into the southern High Plains, a deep and dry boundary layer will compensate for weaker vertical wind shear to support a severe gust threat in association with dry downbursts, driven by evaporative cooling. ...Upper MS Valley... A narrow tongue of at least mid 60s F surface dewpoints will advect ahead of a surface trough/cold front Tuesday afternoon. Though mid-level lapse rates may be modest, the rich low-level moisture will support 2000-3000 J/kg MLCAPE. Furthermore, southwesterly surface winds beneath stronger northwesterly flow aloft support modestly elongated and curved hodographs, with supercells possible. All severe hazards are possible with these storms, including an instance or two of 2+ inch diameter hail and perhaps a couple of tornadoes. An upgrade to Slight Risk may be needed in future outlooks if consensus and consistency among guidance members indicates relatively greater storm coverage. ...Portions of the Gulf Coast... Another day of deep-layer north-northwesterly flow, atop a very moist boundary layer (i.e. 70s F surface dewpoints), will encourage multicellular development amid 1000-2000 J/kg MLCAPE. The stronger storm cores may support wet downdrafts, the strongest of which may produce isolated wind damage. ..Squitieri.. 08/23/2026 NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z
Updated: Sun Aug 23 19:30:56 UTC 2026 (
