Storm Prediction Center

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0224 AM CDT Mon May 18 2026 Valid 201200Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MID ATLANTIC AND SOUTHERN HIGH PLAINS... ...SUMMARY... Scattered thunderstorm activity across the Mid-Atlantic region Wednesday may pose a risk for wind and hail. Isolated thunderstorms within the upslope regime in western Texas/eastern New Mexico will also pose a risk for large hail. ...Discussion... The mid-level trough across the Great Lakes will continue to lift northward into Canada D3/Wednesday. A cold front will extend from the Northeast southward across the southern Ohio Valley into the lower Mississippi Valley and westward into southwestern Texas. Near the front across the Mid-Atlantic, sufficient deep layer shear and MLCAPE will be in place to support a few organized storms, with potential for damaging winds and large hail which supports inclusion of a Marginal Risk. Further south across western Texas, isolated to scattered afternoon thunderstorms may develop south of the front within the upslope flow regime across western Texas into eastern New Mexico. Though deep layer shear will be generally weak, moderate instability and steep low to mid-level lapse rates may support a few instances of large hail and severe winds. ..Thornton.. 05/18/2026 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0150 AM CDT Mon May 18 2026 Valid 191200Z - 201200Z ...Synopsis... A broad mid-level trough will meander over the Intermountain West tomorrow (Tuesday), encouraging weak surface troughing over the Desert Southwest. Southerly flow will increase with daytime heating and boundary-layer mixing, with 15 mph sustained wind speeds likely amid 15-20 percent RH. Elevated highlights were introduced for central and southern New Mexico and immediate surrounding areas, where fuels are dry. ..Squitieri.. 05/18/2026 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0150 AM CDT Mon May 18 2026 Valid 191200Z - 201200Z ...Synopsis... A broad mid-level trough will meander over the Intermountain West tomorrow (Tuesday), encouraging weak surface troughing over the Desert Southwest. Southerly flow will increase with daytime heating and boundary-layer mixing, with 15 mph sustained wind speeds likely amid 15-20 percent RH. Elevated highlights were introduced for central and southern New Mexico and immediate surrounding areas, where fuels are dry. ..Squitieri.. 05/18/2026 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0150 AM CDT Mon May 18 2026 Valid 191200Z - 201200Z ...Synopsis... A broad mid-level trough will meander over the Intermountain West tomorrow (Tuesday), encouraging weak surface troughing over the Desert Southwest. Southerly flow will increase with daytime heating and boundary-layer mixing, with 15 mph sustained wind speeds likely amid 15-20 percent RH. Elevated highlights were introduced for central and southern New Mexico and immediate surrounding areas, where fuels are dry. ..Squitieri.. 05/18/2026 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0150 AM CDT Mon May 18 2026 Valid 191200Z - 201200Z ...Synopsis... A broad mid-level trough will meander over the Intermountain West tomorrow (Tuesday), encouraging weak surface troughing over the Desert Southwest. Southerly flow will increase with daytime heating and boundary-layer mixing, with 15 mph sustained wind speeds likely amid 15-20 percent RH. Elevated highlights were introduced for central and southern New Mexico and immediate surrounding areas, where fuels are dry. ..Squitieri.. 05/18/2026 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

WW 0219 Status Updates
STATUS REPORT ON WW 219 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 35 NNW IRK TO 5 SSE OTM TO 25 SW CID TO 20 ENE CID TO 10 W DBQ TO 20 SW LNR TO 20 NNW LNR TO 5 SSE VOK. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 0767. ..MARSH..05/18/26 ATTN...WFO...ARX...DMX...DVN... STATUS REPORT FOR WS 219 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS IAC031-061-087-101-103-105-177-183-180740- IA . IOWA COUNTIES INCLUDED ARE CEDAR DUBUQUE HENRY JEFFERSON JOHNSON JONES VAN BUREN WASHINGTON WIC043-103-180740- WI . WISCONSIN COUNTIES INCLUDED ARE GRANT RICHLAND THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 0219 Status Updates
STATUS REPORT ON WW 219 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 35 NNW IRK TO 5 SSE OTM TO 25 SW CID TO 20 ENE CID TO 10 W DBQ TO 20 SW LNR TO 20 NNW LNR TO 5 SSE VOK. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 0767. ..MARSH..05/18/26 ATTN...WFO...ARX...DMX...DVN... STATUS REPORT FOR WS 219 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS IAC031-061-087-101-103-105-177-183-180740- IA . IOWA COUNTIES INCLUDED ARE CEDAR DUBUQUE HENRY JEFFERSON JOHNSON JONES VAN BUREN WASHINGTON WIC043-103-180740- WI . WISCONSIN COUNTIES INCLUDED ARE GRANT RICHLAND THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 219 SEVERE TSTM IA MN WI 180410Z - 180900Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 219 NWS Storm Prediction Center Norman OK 1110 PM CDT Sun May 17 2026 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Eastern Iowa Far Southeastern Minnesota Southwest Wisconsin * Effective this Sunday night and Monday morning from 1110 PM until 400 AM CDT. * Primary threats include... Scattered damaging wind gusts to 65 mph possible A tornado or two possible SUMMARY...A squall line will move into the Watch area from the west tonight. Damaging gusts will be the primary severe hazard with the stronger surges of thunderstorm outflow but a brief tornado is also possible. The severe thunderstorm watch area is approximately along and 40 statute miles east and west of a line from 30 miles east of La Crosse WI to 40 miles south southeast of Ottumwa IA. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU9). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...CONTINUE...WW 216...WW 218... AVIATION...A few severe thunderstorms with hail surface and aloft to inches. Extreme turbulence and surface wind gusts to 55 knots. A few cumulonimbi with maximum tops to 400. Mean storm motion vector 25040. ...Smith Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0124 AM CDT Mon May 18 2026 Valid 181200Z - 191200Z ...EXTREMELY CRITICAL FIRE WEATHER AREA FOR PORTIONS OF EXTREME EASTERN NEW MEXICO...EXTREME SOUTHEASTERN COLORADO...FAR SOUTHWESTERN KANSAS...PARTS OF THE TEXAS AND OKLAHOMA PANHANDLES... ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE SOUTHERN HIGH PLAINS... ...Synopsis... ***Dangerous fire weather conditions expected across parts of the southern High Plains*** ...Southwest into the southern High Plains... A pronounced mid-level trough will eject over the Plains, resulting in surface cyclone deepening over southwest Kansas, which will promote widespread, dangerously dry and windy conditions across parts of the Southwest into the southern High Plains today. A dryline will sharpen across southwestern Kansas into far western Oklahoma and northwest Texas by afternoon, with a very dry boundary layer mixing up to 500 mb in the post-dryline environment. Given strong downward mixing, as well as surface gradient flow with the deepening cyclone, widespread 20-30 mph sustained west-southwesterly surface winds overlapping with 5-15 percent RH is expected. These conditions are likely for several hours across much of New Mexico, to southwestern Kansas and points in between, necessitating the maintenance of Critical highlights. Extremely Critical highlights remain in place where confidence is highest in sustained surface winds exceeding 30 mph amid single-digit RH, and where the ERCs of fuel-loaded grasses exceed the 95th percentile. Guidance consensus suggests that this volatile overlap of favorable meteorological conditions and fuels will occur over extreme eastern New Mexico into the Oklahoma/Texas Panhandles and southwestern Kansas, immediately behind the dryline. The combination of the very strong surface winds/RH, critically dry fuels, and exacerbation of potential holdover fires will all support wildfire spread at a life-threateningly fast pace. The danger to the fire spread may be compounded later in the evening and early overnight hours, when the surface cold front sweeps into the region, resulting in a dramatic shift of the surface winds from westerly to northerly, pivoting any ongoing fire fronts accordingly. ...Sacramento Valley in California... A mid-level north-northwesterly wind maximum will overspread northern California during the afternoon hours, when a dry boundary layer is poised to mix up to the 700-500 mb layer. Such conditions will encourage enough downward mixing, in tandem with downslope flow, to support Elevated wildfire-spread conditions in the Sacramento Valley this afternoon. Sustained northerly surface winds in the 15-20 mph range coinciding with 15-20 percent RH will overlap with receptive fuels for at least a few hours, warranting fire weather highlights. ..Squitieri.. 05/18/2026 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0124 AM CDT Mon May 18 2026 Valid 181200Z - 191200Z ...EXTREMELY CRITICAL FIRE WEATHER AREA FOR PORTIONS OF EXTREME EASTERN NEW MEXICO...EXTREME SOUTHEASTERN COLORADO...FAR SOUTHWESTERN KANSAS...PARTS OF THE TEXAS AND OKLAHOMA PANHANDLES... ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE SOUTHERN HIGH PLAINS... ...Synopsis... ***Dangerous fire weather conditions expected across parts of the southern High Plains*** ...Southwest into the southern High Plains... A pronounced mid-level trough will eject over the Plains, resulting in surface cyclone deepening over southwest Kansas, which will promote widespread, dangerously dry and windy conditions across parts of the Southwest into the southern High Plains today. A dryline will sharpen across southwestern Kansas into far western Oklahoma and northwest Texas by afternoon, with a very dry boundary layer mixing up to 500 mb in the post-dryline environment. Given strong downward mixing, as well as surface gradient flow with the deepening cyclone, widespread 20-30 mph sustained west-southwesterly surface winds overlapping with 5-15 percent RH is expected. These conditions are likely for several hours across much of New Mexico, to southwestern Kansas and points in between, necessitating the maintenance of Critical highlights. Extremely Critical highlights remain in place where confidence is highest in sustained surface winds exceeding 30 mph amid single-digit RH, and where the ERCs of fuel-loaded grasses exceed the 95th percentile. Guidance consensus suggests that this volatile overlap of favorable meteorological conditions and fuels will occur over extreme eastern New Mexico into the Oklahoma/Texas Panhandles and southwestern Kansas, immediately behind the dryline. The combination of the very strong surface winds/RH, critically dry fuels, and exacerbation of potential holdover fires will all support wildfire spread at a life-threateningly fast pace. The danger to the fire spread may be compounded later in the evening and early overnight hours, when the surface cold front sweeps into the region, resulting in a dramatic shift of the surface winds from westerly to northerly, pivoting any ongoing fire fronts accordingly. ...Sacramento Valley in California... A mid-level north-northwesterly wind maximum will overspread northern California during the afternoon hours, when a dry boundary layer is poised to mix up to the 700-500 mb layer. Such conditions will encourage enough downward mixing, in tandem with downslope flow, to support Elevated wildfire-spread conditions in the Sacramento Valley this afternoon. Sustained northerly surface winds in the 15-20 mph range coinciding with 15-20 percent RH will overlap with receptive fuels for at least a few hours, warranting fire weather highlights. ..Squitieri.. 05/18/2026 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0124 AM CDT Mon May 18 2026 Valid 181200Z - 191200Z ...EXTREMELY CRITICAL FIRE WEATHER AREA FOR PORTIONS OF EXTREME EASTERN NEW MEXICO...EXTREME SOUTHEASTERN COLORADO...FAR SOUTHWESTERN KANSAS...PARTS OF THE TEXAS AND OKLAHOMA PANHANDLES... ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE SOUTHERN HIGH PLAINS... ...Synopsis... ***Dangerous fire weather conditions expected across parts of the southern High Plains*** ...Southwest into the southern High Plains... A pronounced mid-level trough will eject over the Plains, resulting in surface cyclone deepening over southwest Kansas, which will promote widespread, dangerously dry and windy conditions across parts of the Southwest into the southern High Plains today. A dryline will sharpen across southwestern Kansas into far western Oklahoma and northwest Texas by afternoon, with a very dry boundary layer mixing up to 500 mb in the post-dryline environment. Given strong downward mixing, as well as surface gradient flow with the deepening cyclone, widespread 20-30 mph sustained west-southwesterly surface winds overlapping with 5-15 percent RH is expected. These conditions are likely for several hours across much of New Mexico, to southwestern Kansas and points in between, necessitating the maintenance of Critical highlights. Extremely Critical highlights remain in place where confidence is highest in sustained surface winds exceeding 30 mph amid single-digit RH, and where the ERCs of fuel-loaded grasses exceed the 95th percentile. Guidance consensus suggests that this volatile overlap of favorable meteorological conditions and fuels will occur over extreme eastern New Mexico into the Oklahoma/Texas Panhandles and southwestern Kansas, immediately behind the dryline. The combination of the very strong surface winds/RH, critically dry fuels, and exacerbation of potential holdover fires will all support wildfire spread at a life-threateningly fast pace. The danger to the fire spread may be compounded later in the evening and early overnight hours, when the surface cold front sweeps into the region, resulting in a dramatic shift of the surface winds from westerly to northerly, pivoting any ongoing fire fronts accordingly. ...Sacramento Valley in California... A mid-level north-northwesterly wind maximum will overspread northern California during the afternoon hours, when a dry boundary layer is poised to mix up to the 700-500 mb layer. Such conditions will encourage enough downward mixing, in tandem with downslope flow, to support Elevated wildfire-spread conditions in the Sacramento Valley this afternoon. Sustained northerly surface winds in the 15-20 mph range coinciding with 15-20 percent RH will overlap with receptive fuels for at least a few hours, warranting fire weather highlights. ..Squitieri.. 05/18/2026 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

Public Severe Weather Outlook
PUBLIC SEVERE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0106 AM CDT MON MAY 18 2026 ...Severe thunderstorms expected over parts of the south-central Plains and mid Missouri Valley this afternoon and evening... * LOCATIONS... Iowa Central and Eastern Kansas Northwest Missouri Southeast Nebraska Northern Oklahoma * HAZARDS... Several tornadoes, a couple intense Scattered damaging winds, some hurricane force Widespread baseball-size hail * SUMMARY... Numerous severe thunderstorms are expected this afternoon and evening across the south-central Plains and mid Missouri Valley. Supercells capable of very large hail and strong to intense tornadoes are most likely from central Kansas and southeast Nebraska into Iowa and northwest Missouri. Preparedness actions... Review your severe weather safety procedures for the possibility of dangerous weather today. Stay tuned to NOAA Weather Radio, weather.gov, or other media for watches and warnings. A tornado watch means that conditions are favorable for tornadoes to form during the next several hours. If a tornado warning is issued for your area, move to a place of safety, ideally in a basement or interior room on the lowest floor of a sturdy building. && Read more

Public Severe Weather Outlook
PUBLIC SEVERE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0106 AM CDT MON MAY 18 2026 ...Severe thunderstorms expected over parts of the south-central Plains and mid Missouri Valley this afternoon and evening... * LOCATIONS... Iowa Central and Eastern Kansas Northwest Missouri Southeast Nebraska Northern Oklahoma * HAZARDS... Several tornadoes, a couple intense Scattered damaging winds, some hurricane force Widespread baseball-size hail * SUMMARY... Numerous severe thunderstorms are expected this afternoon and evening across the south-central Plains and mid Missouri Valley. Supercells capable of very large hail and strong to intense tornadoes are most likely from central Kansas and southeast Nebraska into Iowa and northwest Missouri. Preparedness actions... Review your severe weather safety procedures for the possibility of dangerous weather today. Stay tuned to NOAA Weather Radio, weather.gov, or other media for watches and warnings. A tornado watch means that conditions are favorable for tornadoes to form during the next several hours. If a tornado warning is issued for your area, move to a place of safety, ideally in a basement or interior room on the lowest floor of a sturdy building. && Read more

Public Severe Weather Outlook
PUBLIC SEVERE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0106 AM CDT MON MAY 18 2026 ...Severe thunderstorms expected over parts of the south-central Plains and mid Missouri Valley this afternoon and evening... * LOCATIONS... Iowa Central and Eastern Kansas Northwest Missouri Southeast Nebraska Northern Oklahoma * HAZARDS... Several tornadoes, a couple intense Scattered damaging winds, some hurricane force Widespread baseball-size hail * SUMMARY... Numerous severe thunderstorms are expected this afternoon and evening across the south-central Plains and mid Missouri Valley. Supercells capable of very large hail and strong to intense tornadoes are most likely from central Kansas and southeast Nebraska into Iowa and northwest Missouri. Preparedness actions... Review your severe weather safety procedures for the possibility of dangerous weather today. Stay tuned to NOAA Weather Radio, weather.gov, or other media for watches and warnings. A tornado watch means that conditions are favorable for tornadoes to form during the next several hours. If a tornado warning is issued for your area, move to a place of safety, ideally in a basement or interior room on the lowest floor of a sturdy building. && Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1254 AM CDT Mon May 18 2026 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE GREAT LAKES TO THE SOUTHERN PLAINS... ...SUMMARY... Widely scattered severe thunderstorms will be possible along a cold front extending from the Great Lakes into the Ohio Valley and the southern Plains on Tuesday. Damaging winds and large hail will be the primary threats. ...Synopsis... A mid-level trough will lift across the Great Lakes Region on D2/Tuesday with a surface low moving east across southern Ontario and Quebec. A trailing cold front will be located from the Great Lakes south into the Ohio and mid Mississippi Valleys into the Southern Plains. Convection will likely be ongoing across this boundary at the beginning of the D2/Tuesday period. ...Great Lakes Vicinity to the Lower Ohio Valley... Some convection may be ongoing across the cold front towards the beginning of the D2 period, with additional development likely by the afternoon along the eastward shifting cold front. Enhanced mid-level flow aloft and weak to moderate instability will support organized storms with potential for damaging winds and isolated large hail. Additional afternoon thunderstorm development may extend into the Northeast with potential for large hail and damaging wind. ...Mid Mississippi Valley to Southern Plains... Convection will be ongoing at the start of the period from the mid Mississippi Valley driven by the cold front and potential cold pool propagation. These boundaries will be the focus of re-intensification of convection in the afternoon. Mid-level flow aloft will be weaker across the region but sufficient shear for organization should remain in place. A plume of more favorable moderate to strong instability will be available across central/northern Texas into southern Oklahoma. With afternoon development, steep low to mid level lapse rates and moderate instability will support potential for a few large hail reports. With time, upscale growth will support a downstream damaging wind risk. ..Thornton.. 05/18/2026 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1254 AM CDT Mon May 18 2026 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE GREAT LAKES TO THE SOUTHERN PLAINS... ...SUMMARY... Widely scattered severe thunderstorms will be possible along a cold front extending from the Great Lakes into the Ohio Valley and the southern Plains on Tuesday. Damaging winds and large hail will be the primary threats. ...Synopsis... A mid-level trough will lift across the Great Lakes Region on D2/Tuesday with a surface low moving east across southern Ontario and Quebec. A trailing cold front will be located from the Great Lakes south into the Ohio and mid Mississippi Valleys into the Southern Plains. Convection will likely be ongoing across this boundary at the beginning of the D2/Tuesday period. ...Great Lakes Vicinity to the Lower Ohio Valley... Some convection may be ongoing across the cold front towards the beginning of the D2 period, with additional development likely by the afternoon along the eastward shifting cold front. Enhanced mid-level flow aloft and weak to moderate instability will support organized storms with potential for damaging winds and isolated large hail. Additional afternoon thunderstorm development may extend into the Northeast with potential for large hail and damaging wind. ...Mid Mississippi Valley to Southern Plains... Convection will be ongoing at the start of the period from the mid Mississippi Valley driven by the cold front and potential cold pool propagation. These boundaries will be the focus of re-intensification of convection in the afternoon. Mid-level flow aloft will be weaker across the region but sufficient shear for organization should remain in place. A plume of more favorable moderate to strong instability will be available across central/northern Texas into southern Oklahoma. With afternoon development, steep low to mid level lapse rates and moderate instability will support potential for a few large hail reports. With time, upscale growth will support a downstream damaging wind risk. ..Thornton.. 05/18/2026 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1254 AM CDT Mon May 18 2026 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE GREAT LAKES TO THE SOUTHERN PLAINS... ...SUMMARY... Widely scattered severe thunderstorms will be possible along a cold front extending from the Great Lakes into the Ohio Valley and the southern Plains on Tuesday. Damaging winds and large hail will be the primary threats. ...Synopsis... A mid-level trough will lift across the Great Lakes Region on D2/Tuesday with a surface low moving east across southern Ontario and Quebec. A trailing cold front will be located from the Great Lakes south into the Ohio and mid Mississippi Valleys into the Southern Plains. Convection will likely be ongoing across this boundary at the beginning of the D2/Tuesday period. ...Great Lakes Vicinity to the Lower Ohio Valley... Some convection may be ongoing across the cold front towards the beginning of the D2 period, with additional development likely by the afternoon along the eastward shifting cold front. Enhanced mid-level flow aloft and weak to moderate instability will support organized storms with potential for damaging winds and isolated large hail. Additional afternoon thunderstorm development may extend into the Northeast with potential for large hail and damaging wind. ...Mid Mississippi Valley to Southern Plains... Convection will be ongoing at the start of the period from the mid Mississippi Valley driven by the cold front and potential cold pool propagation. These boundaries will be the focus of re-intensification of convection in the afternoon. Mid-level flow aloft will be weaker across the region but sufficient shear for organization should remain in place. A plume of more favorable moderate to strong instability will be available across central/northern Texas into southern Oklahoma. With afternoon development, steep low to mid level lapse rates and moderate instability will support potential for a few large hail reports. With time, upscale growth will support a downstream damaging wind risk. ..Thornton.. 05/18/2026 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Mon May 18 2026 Valid 181200Z - 191200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN/SOUTH-CENTRAL KANSAS AND SOUTHEAST NEBRASKA/FAR NORTHWEST MISSOURI... ...SUMMARY... Numerous severe thunderstorms are expected this afternoon and evening across the south-central Plains and Middle Missouri Valley. Supercells capable of very large hail and strong to intense tornadoes are most likely from central Kansas and southeast Nebraska into Iowa and northwest Missouri. ...Central Plains and Midwest... A regional outbreak of severe storms, potentially including strong/intense tornadoes (EF2/EF3+), is expected across the central Plains during the late afternoon and evening, although some uncertainties persist regarding the upper-end magnitude/spatial details of the heightened tornado potential. An extensive MCS exists early in the overnight from eastern/central Iowa southwestward into northeast/central Kansas, where regenerative/repetitive storms persist. This MCS should weaken/lose integrity through the early morning, although convection may regenerate and intensify again along composite outflow, eastward across the middle Mississippi Valley and lower Ohio Valley and potentially parts of the Great Lakes within a destabilizing air mass this afternoon. Damaging winds should be the most probable risk, although some tornado and hail potential will exist as well. The western fringe of this remnant cold pool will modify early today with a steady northward flux of low-level moisture, with a very unstable environment unfolding by mid/late afternoon across south-central/eastern Kansas into far west/northwest Missouri and Iowa/far southeast Nebraska. As a shortwave trough/speed max emerges from the central Rockies, deep convective development is expected along the initially stalled or slow-moving northeast/southwest-oriented front across central/northeast Kansas and southeast Nebraska and western Iowa by late afternoon. This increasingly rich low-level moisture will reside beneath an elevated mixed layer characterized by 8-9 C/km mid-level lapse rates, resulting in MLCAPE 3000-4000 J/kg. Mass response to the ejecting wave, along with a northeastward-translating 60-70 kt mid-level jet, and a significantly strengthening low-level jet by sunset, will yield increasingly favorable wind profiles for intense supercells capable of very large hail and tornadoes. This may includes strong and potentially intense tornadoes (EF2/EF3+). That said, the duration of a semi-discrete storm mode remains a key question, given the parallel orientation of the stalled front and the deep-layer shear vectors, and that the front will trend more southeastward-progressive during the evening. Thus, the strong/potentially intense tornado threat will peak prior to upscale growth into line segments along the front, with severe outflow gusts and embedded circulations becoming the main concerns over time tonight as storms progress east-southeastward across the Lower Missouri Valley and middle Mississippi Valley. ...Oklahoma and western North Texas... Storm development along the dryline across western Oklahoma into western North Texas/Lower Rolling Plains is more uncertain given more limited forcing for ascent. If/where storms do form, there is the potential for very large hail and a conditional risk for tornadoes. A consistently forecast flow weakness above 400 mb by late afternoon/evening does not appear favorable for particularly long-lived storms if they do form. ...Mid-Atlantic/Northeast States... Influenced by terrain and a surface trough, isolated strong to locally severe storms capable of wind damage could occur this afternoon within a moderately unstable environment. ..Guyer/Squitieri.. 05/18/2026 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Mon May 18 2026 Valid 181200Z - 191200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN/SOUTH-CENTRAL KANSAS AND SOUTHEAST NEBRASKA/FAR NORTHWEST MISSOURI... ...SUMMARY... Numerous severe thunderstorms are expected this afternoon and evening across the south-central Plains and Middle Missouri Valley. Supercells capable of very large hail and strong to intense tornadoes are most likely from central Kansas and southeast Nebraska into Iowa and northwest Missouri. ...Central Plains and Midwest... A regional outbreak of severe storms, potentially including strong/intense tornadoes (EF2/EF3+), is expected across the central Plains during the late afternoon and evening, although some uncertainties persist regarding the upper-end magnitude/spatial details of the heightened tornado potential. An extensive MCS exists early in the overnight from eastern/central Iowa southwestward into northeast/central Kansas, where regenerative/repetitive storms persist. This MCS should weaken/lose integrity through the early morning, although convection may regenerate and intensify again along composite outflow, eastward across the middle Mississippi Valley and lower Ohio Valley and potentially parts of the Great Lakes within a destabilizing air mass this afternoon. Damaging winds should be the most probable risk, although some tornado and hail potential will exist as well. The western fringe of this remnant cold pool will modify early today with a steady northward flux of low-level moisture, with a very unstable environment unfolding by mid/late afternoon across south-central/eastern Kansas into far west/northwest Missouri and Iowa/far southeast Nebraska. As a shortwave trough/speed max emerges from the central Rockies, deep convective development is expected along the initially stalled or slow-moving northeast/southwest-oriented front across central/northeast Kansas and southeast Nebraska and western Iowa by late afternoon. This increasingly rich low-level moisture will reside beneath an elevated mixed layer characterized by 8-9 C/km mid-level lapse rates, resulting in MLCAPE 3000-4000 J/kg. Mass response to the ejecting wave, along with a northeastward-translating 60-70 kt mid-level jet, and a significantly strengthening low-level jet by sunset, will yield increasingly favorable wind profiles for intense supercells capable of very large hail and tornadoes. This may includes strong and potentially intense tornadoes (EF2/EF3+). That said, the duration of a semi-discrete storm mode remains a key question, given the parallel orientation of the stalled front and the deep-layer shear vectors, and that the front will trend more southeastward-progressive during the evening. Thus, the strong/potentially intense tornado threat will peak prior to upscale growth into line segments along the front, with severe outflow gusts and embedded circulations becoming the main concerns over time tonight as storms progress east-southeastward across the Lower Missouri Valley and middle Mississippi Valley. ...Oklahoma and western North Texas... Storm development along the dryline across western Oklahoma into western North Texas/Lower Rolling Plains is more uncertain given more limited forcing for ascent. If/where storms do form, there is the potential for very large hail and a conditional risk for tornadoes. A consistently forecast flow weakness above 400 mb by late afternoon/evening does not appear favorable for particularly long-lived storms if they do form. ...Mid-Atlantic/Northeast States... Influenced by terrain and a surface trough, isolated strong to locally severe storms capable of wind damage could occur this afternoon within a moderately unstable environment. ..Guyer/Squitieri.. 05/18/2026 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Mon May 18 2026 Valid 181200Z - 191200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN/SOUTH-CENTRAL KANSAS AND SOUTHEAST NEBRASKA/FAR NORTHWEST MISSOURI... ...SUMMARY... Numerous severe thunderstorms are expected this afternoon and evening across the south-central Plains and Middle Missouri Valley. Supercells capable of very large hail and strong to intense tornadoes are most likely from central Kansas and southeast Nebraska into Iowa and northwest Missouri. ...Central Plains and Midwest... A regional outbreak of severe storms, potentially including strong/intense tornadoes (EF2/EF3+), is expected across the central Plains during the late afternoon and evening, although some uncertainties persist regarding the upper-end magnitude/spatial details of the heightened tornado potential. An extensive MCS exists early in the overnight from eastern/central Iowa southwestward into northeast/central Kansas, where regenerative/repetitive storms persist. This MCS should weaken/lose integrity through the early morning, although convection may regenerate and intensify again along composite outflow, eastward across the middle Mississippi Valley and lower Ohio Valley and potentially parts of the Great Lakes within a destabilizing air mass this afternoon. Damaging winds should be the most probable risk, although some tornado and hail potential will exist as well. The western fringe of this remnant cold pool will modify early today with a steady northward flux of low-level moisture, with a very unstable environment unfolding by mid/late afternoon across south-central/eastern Kansas into far west/northwest Missouri and Iowa/far southeast Nebraska. As a shortwave trough/speed max emerges from the central Rockies, deep convective development is expected along the initially stalled or slow-moving northeast/southwest-oriented front across central/northeast Kansas and southeast Nebraska and western Iowa by late afternoon. This increasingly rich low-level moisture will reside beneath an elevated mixed layer characterized by 8-9 C/km mid-level lapse rates, resulting in MLCAPE 3000-4000 J/kg. Mass response to the ejecting wave, along with a northeastward-translating 60-70 kt mid-level jet, and a significantly strengthening low-level jet by sunset, will yield increasingly favorable wind profiles for intense supercells capable of very large hail and tornadoes. This may includes strong and potentially intense tornadoes (EF2/EF3+). That said, the duration of a semi-discrete storm mode remains a key question, given the parallel orientation of the stalled front and the deep-layer shear vectors, and that the front will trend more southeastward-progressive during the evening. Thus, the strong/potentially intense tornado threat will peak prior to upscale growth into line segments along the front, with severe outflow gusts and embedded circulations becoming the main concerns over time tonight as storms progress east-southeastward across the Lower Missouri Valley and middle Mississippi Valley. ...Oklahoma and western North Texas... Storm development along the dryline across western Oklahoma into western North Texas/Lower Rolling Plains is more uncertain given more limited forcing for ascent. If/where storms do form, there is the potential for very large hail and a conditional risk for tornadoes. A consistently forecast flow weakness above 400 mb by late afternoon/evening does not appear favorable for particularly long-lived storms if they do form. ...Mid-Atlantic/Northeast States... Influenced by terrain and a surface trough, isolated strong to locally severe storms capable of wind damage could occur this afternoon within a moderately unstable environment. ..Guyer/Squitieri.. 05/18/2026 Read more