Severe Storms

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0700 AM CDT Fri Apr 18 2025 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE SOUTHERN PLAINS INTO THE MID MISSISSIPPI VALLEY AND UPPER GREAT LAKES... ...SUMMARY... Scattered severe thunderstorms are possible from parts of the southern Plains northeastward toward the upper Great Lakes, mainly from late afternoon into early Saturday morning. Large to very large hail and severe wind gusts should be the main hazards, especially across the southern Plains where storms will be more concentrated. A few tornadoes also appear possible. ...Upper Great Lakes to Mid Mississippi Valley... Ongoing, mostly elevated thunderstorms aided by persistent low-level warm/moist advection and steep mid-level lapse rates should continue to pose a large hail and damaging wind threat as they spread quickly eastward across southern WI this morning. This activity should eventually weaken later this morning as it continues moving across Lower MI into a less unstable environment. Behind this initial activity, the surface warm sector will attempt to spread northward across parts of the Upper Midwest and Great Lakes today, as longwave troughing gradually develops eastward over the northern/central Plains and Southwest. Given the positive tilt/orientation of this upper troughing and enhanced southwesterly flow aloft expected to persist through the period, a strong cold front should make only slow southeastward progress. A cap will likely inhibit surface-based convective development until peak afternoon heating and frontal forcing can help lift parcels to their LFC. Given nebulous forcing aloft, there is still a fair amount of uncertainty regarding overall convective coverage this afternoon/evening. Even so, any thunderstorms that can develop along or ahead of the front could pose a threat for severe hail and damaging winds, with strong deep-layer shear aiding updraft organization. This severe threat may persist for much of the evening, and perhaps continuing into the early overnight hours. ...Southern Plains to the Ozarks... The southern portion of the cold front is forecast to decelerate and eventually stall over parts of OK later today. A dryline will extend southward from a weak frontal low across northwest to west-central TX by late afternoon. Even with widespread mid/high-level cloudiness present, robust daytime heating of the moist warm sector is anticipated across the southern Plains today. The low-level cap should eventually be breached by late afternoon/early evening (around 22-00Z), particularly along/near the cold front, and perhaps the front/dryline intersection as well. Strong southwesterly flow aloft and related deep-layer shear will likely support organized severe convection. Initial supercell development should pose a threat for large to very large hail, potentially up to 2-3 inches in diameter. With time, upscale growth into multiple clusters/short line segments is expected through the evening into early Saturday morning, as a south-southwesterly low-level jet gradually strengthens. An increase in the severe/damaging wind threat is anticipated as this mode transition occurs. The threat for a few tornadoes remains apparent, especially across parts of OK along/south of the front, as favorable low-level shear will be present this evening where supercells may still exist. Even with a higher concentration of thunderstorms expected across the southern Plains, the messy convective mode this evening and tendency for convection to be undercut by the cold front currently limit confidence in delineating a corridor of greater severe hail/wind potential. ..Gleason/Broyles.. 04/18/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0700 AM CDT Fri Apr 18 2025 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE SOUTHERN PLAINS INTO THE MID MISSISSIPPI VALLEY AND UPPER GREAT LAKES... ...SUMMARY... Scattered severe thunderstorms are possible from parts of the southern Plains northeastward toward the upper Great Lakes, mainly from late afternoon into early Saturday morning. Large to very large hail and severe wind gusts should be the main hazards, especially across the southern Plains where storms will be more concentrated. A few tornadoes also appear possible. ...Upper Great Lakes to Mid Mississippi Valley... Ongoing, mostly elevated thunderstorms aided by persistent low-level warm/moist advection and steep mid-level lapse rates should continue to pose a large hail and damaging wind threat as they spread quickly eastward across southern WI this morning. This activity should eventually weaken later this morning as it continues moving across Lower MI into a less unstable environment. Behind this initial activity, the surface warm sector will attempt to spread northward across parts of the Upper Midwest and Great Lakes today, as longwave troughing gradually develops eastward over the northern/central Plains and Southwest. Given the positive tilt/orientation of this upper troughing and enhanced southwesterly flow aloft expected to persist through the period, a strong cold front should make only slow southeastward progress. A cap will likely inhibit surface-based convective development until peak afternoon heating and frontal forcing can help lift parcels to their LFC. Given nebulous forcing aloft, there is still a fair amount of uncertainty regarding overall convective coverage this afternoon/evening. Even so, any thunderstorms that can develop along or ahead of the front could pose a threat for severe hail and damaging winds, with strong deep-layer shear aiding updraft organization. This severe threat may persist for much of the evening, and perhaps continuing into the early overnight hours. ...Southern Plains to the Ozarks... The southern portion of the cold front is forecast to decelerate and eventually stall over parts of OK later today. A dryline will extend southward from a weak frontal low across northwest to west-central TX by late afternoon. Even with widespread mid/high-level cloudiness present, robust daytime heating of the moist warm sector is anticipated across the southern Plains today. The low-level cap should eventually be breached by late afternoon/early evening (around 22-00Z), particularly along/near the cold front, and perhaps the front/dryline intersection as well. Strong southwesterly flow aloft and related deep-layer shear will likely support organized severe convection. Initial supercell development should pose a threat for large to very large hail, potentially up to 2-3 inches in diameter. With time, upscale growth into multiple clusters/short line segments is expected through the evening into early Saturday morning, as a south-southwesterly low-level jet gradually strengthens. An increase in the severe/damaging wind threat is anticipated as this mode transition occurs. The threat for a few tornadoes remains apparent, especially across parts of OK along/south of the front, as favorable low-level shear will be present this evening where supercells may still exist. Even with a higher concentration of thunderstorms expected across the southern Plains, the messy convective mode this evening and tendency for convection to be undercut by the cold front currently limit confidence in delineating a corridor of greater severe hail/wind potential. ..Gleason/Broyles.. 04/18/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0700 AM CDT Fri Apr 18 2025 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE SOUTHERN PLAINS INTO THE MID MISSISSIPPI VALLEY AND UPPER GREAT LAKES... ...SUMMARY... Scattered severe thunderstorms are possible from parts of the southern Plains northeastward toward the upper Great Lakes, mainly from late afternoon into early Saturday morning. Large to very large hail and severe wind gusts should be the main hazards, especially across the southern Plains where storms will be more concentrated. A few tornadoes also appear possible. ...Upper Great Lakes to Mid Mississippi Valley... Ongoing, mostly elevated thunderstorms aided by persistent low-level warm/moist advection and steep mid-level lapse rates should continue to pose a large hail and damaging wind threat as they spread quickly eastward across southern WI this morning. This activity should eventually weaken later this morning as it continues moving across Lower MI into a less unstable environment. Behind this initial activity, the surface warm sector will attempt to spread northward across parts of the Upper Midwest and Great Lakes today, as longwave troughing gradually develops eastward over the northern/central Plains and Southwest. Given the positive tilt/orientation of this upper troughing and enhanced southwesterly flow aloft expected to persist through the period, a strong cold front should make only slow southeastward progress. A cap will likely inhibit surface-based convective development until peak afternoon heating and frontal forcing can help lift parcels to their LFC. Given nebulous forcing aloft, there is still a fair amount of uncertainty regarding overall convective coverage this afternoon/evening. Even so, any thunderstorms that can develop along or ahead of the front could pose a threat for severe hail and damaging winds, with strong deep-layer shear aiding updraft organization. This severe threat may persist for much of the evening, and perhaps continuing into the early overnight hours. ...Southern Plains to the Ozarks... The southern portion of the cold front is forecast to decelerate and eventually stall over parts of OK later today. A dryline will extend southward from a weak frontal low across northwest to west-central TX by late afternoon. Even with widespread mid/high-level cloudiness present, robust daytime heating of the moist warm sector is anticipated across the southern Plains today. The low-level cap should eventually be breached by late afternoon/early evening (around 22-00Z), particularly along/near the cold front, and perhaps the front/dryline intersection as well. Strong southwesterly flow aloft and related deep-layer shear will likely support organized severe convection. Initial supercell development should pose a threat for large to very large hail, potentially up to 2-3 inches in diameter. With time, upscale growth into multiple clusters/short line segments is expected through the evening into early Saturday morning, as a south-southwesterly low-level jet gradually strengthens. An increase in the severe/damaging wind threat is anticipated as this mode transition occurs. The threat for a few tornadoes remains apparent, especially across parts of OK along/south of the front, as favorable low-level shear will be present this evening where supercells may still exist. Even with a higher concentration of thunderstorms expected across the southern Plains, the messy convective mode this evening and tendency for convection to be undercut by the cold front currently limit confidence in delineating a corridor of greater severe hail/wind potential. ..Gleason/Broyles.. 04/18/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0700 AM CDT Fri Apr 18 2025 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE SOUTHERN PLAINS INTO THE MID MISSISSIPPI VALLEY AND UPPER GREAT LAKES... ...SUMMARY... Scattered severe thunderstorms are possible from parts of the southern Plains northeastward toward the upper Great Lakes, mainly from late afternoon into early Saturday morning. Large to very large hail and severe wind gusts should be the main hazards, especially across the southern Plains where storms will be more concentrated. A few tornadoes also appear possible. ...Upper Great Lakes to Mid Mississippi Valley... Ongoing, mostly elevated thunderstorms aided by persistent low-level warm/moist advection and steep mid-level lapse rates should continue to pose a large hail and damaging wind threat as they spread quickly eastward across southern WI this morning. This activity should eventually weaken later this morning as it continues moving across Lower MI into a less unstable environment. Behind this initial activity, the surface warm sector will attempt to spread northward across parts of the Upper Midwest and Great Lakes today, as longwave troughing gradually develops eastward over the northern/central Plains and Southwest. Given the positive tilt/orientation of this upper troughing and enhanced southwesterly flow aloft expected to persist through the period, a strong cold front should make only slow southeastward progress. A cap will likely inhibit surface-based convective development until peak afternoon heating and frontal forcing can help lift parcels to their LFC. Given nebulous forcing aloft, there is still a fair amount of uncertainty regarding overall convective coverage this afternoon/evening. Even so, any thunderstorms that can develop along or ahead of the front could pose a threat for severe hail and damaging winds, with strong deep-layer shear aiding updraft organization. This severe threat may persist for much of the evening, and perhaps continuing into the early overnight hours. ...Southern Plains to the Ozarks... The southern portion of the cold front is forecast to decelerate and eventually stall over parts of OK later today. A dryline will extend southward from a weak frontal low across northwest to west-central TX by late afternoon. Even with widespread mid/high-level cloudiness present, robust daytime heating of the moist warm sector is anticipated across the southern Plains today. The low-level cap should eventually be breached by late afternoon/early evening (around 22-00Z), particularly along/near the cold front, and perhaps the front/dryline intersection as well. Strong southwesterly flow aloft and related deep-layer shear will likely support organized severe convection. Initial supercell development should pose a threat for large to very large hail, potentially up to 2-3 inches in diameter. With time, upscale growth into multiple clusters/short line segments is expected through the evening into early Saturday morning, as a south-southwesterly low-level jet gradually strengthens. An increase in the severe/damaging wind threat is anticipated as this mode transition occurs. The threat for a few tornadoes remains apparent, especially across parts of OK along/south of the front, as favorable low-level shear will be present this evening where supercells may still exist. Even with a higher concentration of thunderstorms expected across the southern Plains, the messy convective mode this evening and tendency for convection to be undercut by the cold front currently limit confidence in delineating a corridor of greater severe hail/wind potential. ..Gleason/Broyles.. 04/18/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0700 AM CDT Fri Apr 18 2025 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE SOUTHERN PLAINS INTO THE MID MISSISSIPPI VALLEY AND UPPER GREAT LAKES... ...SUMMARY... Scattered severe thunderstorms are possible from parts of the southern Plains northeastward toward the upper Great Lakes, mainly from late afternoon into early Saturday morning. Large to very large hail and severe wind gusts should be the main hazards, especially across the southern Plains where storms will be more concentrated. A few tornadoes also appear possible. ...Upper Great Lakes to Mid Mississippi Valley... Ongoing, mostly elevated thunderstorms aided by persistent low-level warm/moist advection and steep mid-level lapse rates should continue to pose a large hail and damaging wind threat as they spread quickly eastward across southern WI this morning. This activity should eventually weaken later this morning as it continues moving across Lower MI into a less unstable environment. Behind this initial activity, the surface warm sector will attempt to spread northward across parts of the Upper Midwest and Great Lakes today, as longwave troughing gradually develops eastward over the northern/central Plains and Southwest. Given the positive tilt/orientation of this upper troughing and enhanced southwesterly flow aloft expected to persist through the period, a strong cold front should make only slow southeastward progress. A cap will likely inhibit surface-based convective development until peak afternoon heating and frontal forcing can help lift parcels to their LFC. Given nebulous forcing aloft, there is still a fair amount of uncertainty regarding overall convective coverage this afternoon/evening. Even so, any thunderstorms that can develop along or ahead of the front could pose a threat for severe hail and damaging winds, with strong deep-layer shear aiding updraft organization. This severe threat may persist for much of the evening, and perhaps continuing into the early overnight hours. ...Southern Plains to the Ozarks... The southern portion of the cold front is forecast to decelerate and eventually stall over parts of OK later today. A dryline will extend southward from a weak frontal low across northwest to west-central TX by late afternoon. Even with widespread mid/high-level cloudiness present, robust daytime heating of the moist warm sector is anticipated across the southern Plains today. The low-level cap should eventually be breached by late afternoon/early evening (around 22-00Z), particularly along/near the cold front, and perhaps the front/dryline intersection as well. Strong southwesterly flow aloft and related deep-layer shear will likely support organized severe convection. Initial supercell development should pose a threat for large to very large hail, potentially up to 2-3 inches in diameter. With time, upscale growth into multiple clusters/short line segments is expected through the evening into early Saturday morning, as a south-southwesterly low-level jet gradually strengthens. An increase in the severe/damaging wind threat is anticipated as this mode transition occurs. The threat for a few tornadoes remains apparent, especially across parts of OK along/south of the front, as favorable low-level shear will be present this evening where supercells may still exist. Even with a higher concentration of thunderstorms expected across the southern Plains, the messy convective mode this evening and tendency for convection to be undercut by the cold front currently limit confidence in delineating a corridor of greater severe hail/wind potential. ..Gleason/Broyles.. 04/18/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0700 AM CDT Fri Apr 18 2025 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE SOUTHERN PLAINS INTO THE MID MISSISSIPPI VALLEY AND UPPER GREAT LAKES... ...SUMMARY... Scattered severe thunderstorms are possible from parts of the southern Plains northeastward toward the upper Great Lakes, mainly from late afternoon into early Saturday morning. Large to very large hail and severe wind gusts should be the main hazards, especially across the southern Plains where storms will be more concentrated. A few tornadoes also appear possible. ...Upper Great Lakes to Mid Mississippi Valley... Ongoing, mostly elevated thunderstorms aided by persistent low-level warm/moist advection and steep mid-level lapse rates should continue to pose a large hail and damaging wind threat as they spread quickly eastward across southern WI this morning. This activity should eventually weaken later this morning as it continues moving across Lower MI into a less unstable environment. Behind this initial activity, the surface warm sector will attempt to spread northward across parts of the Upper Midwest and Great Lakes today, as longwave troughing gradually develops eastward over the northern/central Plains and Southwest. Given the positive tilt/orientation of this upper troughing and enhanced southwesterly flow aloft expected to persist through the period, a strong cold front should make only slow southeastward progress. A cap will likely inhibit surface-based convective development until peak afternoon heating and frontal forcing can help lift parcels to their LFC. Given nebulous forcing aloft, there is still a fair amount of uncertainty regarding overall convective coverage this afternoon/evening. Even so, any thunderstorms that can develop along or ahead of the front could pose a threat for severe hail and damaging winds, with strong deep-layer shear aiding updraft organization. This severe threat may persist for much of the evening, and perhaps continuing into the early overnight hours. ...Southern Plains to the Ozarks... The southern portion of the cold front is forecast to decelerate and eventually stall over parts of OK later today. A dryline will extend southward from a weak frontal low across northwest to west-central TX by late afternoon. Even with widespread mid/high-level cloudiness present, robust daytime heating of the moist warm sector is anticipated across the southern Plains today. The low-level cap should eventually be breached by late afternoon/early evening (around 22-00Z), particularly along/near the cold front, and perhaps the front/dryline intersection as well. Strong southwesterly flow aloft and related deep-layer shear will likely support organized severe convection. Initial supercell development should pose a threat for large to very large hail, potentially up to 2-3 inches in diameter. With time, upscale growth into multiple clusters/short line segments is expected through the evening into early Saturday morning, as a south-southwesterly low-level jet gradually strengthens. An increase in the severe/damaging wind threat is anticipated as this mode transition occurs. The threat for a few tornadoes remains apparent, especially across parts of OK along/south of the front, as favorable low-level shear will be present this evening where supercells may still exist. Even with a higher concentration of thunderstorms expected across the southern Plains, the messy convective mode this evening and tendency for convection to be undercut by the cold front currently limit confidence in delineating a corridor of greater severe hail/wind potential. ..Gleason/Broyles.. 04/18/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0700 AM CDT Fri Apr 18 2025 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE SOUTHERN PLAINS INTO THE MID MISSISSIPPI VALLEY AND UPPER GREAT LAKES... ...SUMMARY... Scattered severe thunderstorms are possible from parts of the southern Plains northeastward toward the upper Great Lakes, mainly from late afternoon into early Saturday morning. Large to very large hail and severe wind gusts should be the main hazards, especially across the southern Plains where storms will be more concentrated. A few tornadoes also appear possible. ...Upper Great Lakes to Mid Mississippi Valley... Ongoing, mostly elevated thunderstorms aided by persistent low-level warm/moist advection and steep mid-level lapse rates should continue to pose a large hail and damaging wind threat as they spread quickly eastward across southern WI this morning. This activity should eventually weaken later this morning as it continues moving across Lower MI into a less unstable environment. Behind this initial activity, the surface warm sector will attempt to spread northward across parts of the Upper Midwest and Great Lakes today, as longwave troughing gradually develops eastward over the northern/central Plains and Southwest. Given the positive tilt/orientation of this upper troughing and enhanced southwesterly flow aloft expected to persist through the period, a strong cold front should make only slow southeastward progress. A cap will likely inhibit surface-based convective development until peak afternoon heating and frontal forcing can help lift parcels to their LFC. Given nebulous forcing aloft, there is still a fair amount of uncertainty regarding overall convective coverage this afternoon/evening. Even so, any thunderstorms that can develop along or ahead of the front could pose a threat for severe hail and damaging winds, with strong deep-layer shear aiding updraft organization. This severe threat may persist for much of the evening, and perhaps continuing into the early overnight hours. ...Southern Plains to the Ozarks... The southern portion of the cold front is forecast to decelerate and eventually stall over parts of OK later today. A dryline will extend southward from a weak frontal low across northwest to west-central TX by late afternoon. Even with widespread mid/high-level cloudiness present, robust daytime heating of the moist warm sector is anticipated across the southern Plains today. The low-level cap should eventually be breached by late afternoon/early evening (around 22-00Z), particularly along/near the cold front, and perhaps the front/dryline intersection as well. Strong southwesterly flow aloft and related deep-layer shear will likely support organized severe convection. Initial supercell development should pose a threat for large to very large hail, potentially up to 2-3 inches in diameter. With time, upscale growth into multiple clusters/short line segments is expected through the evening into early Saturday morning, as a south-southwesterly low-level jet gradually strengthens. An increase in the severe/damaging wind threat is anticipated as this mode transition occurs. The threat for a few tornadoes remains apparent, especially across parts of OK along/south of the front, as favorable low-level shear will be present this evening where supercells may still exist. Even with a higher concentration of thunderstorms expected across the southern Plains, the messy convective mode this evening and tendency for convection to be undercut by the cold front currently limit confidence in delineating a corridor of greater severe hail/wind potential. ..Gleason/Broyles.. 04/18/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0700 AM CDT Fri Apr 18 2025 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE SOUTHERN PLAINS INTO THE MID MISSISSIPPI VALLEY AND UPPER GREAT LAKES... ...SUMMARY... Scattered severe thunderstorms are possible from parts of the southern Plains northeastward toward the upper Great Lakes, mainly from late afternoon into early Saturday morning. Large to very large hail and severe wind gusts should be the main hazards, especially across the southern Plains where storms will be more concentrated. A few tornadoes also appear possible. ...Upper Great Lakes to Mid Mississippi Valley... Ongoing, mostly elevated thunderstorms aided by persistent low-level warm/moist advection and steep mid-level lapse rates should continue to pose a large hail and damaging wind threat as they spread quickly eastward across southern WI this morning. This activity should eventually weaken later this morning as it continues moving across Lower MI into a less unstable environment. Behind this initial activity, the surface warm sector will attempt to spread northward across parts of the Upper Midwest and Great Lakes today, as longwave troughing gradually develops eastward over the northern/central Plains and Southwest. Given the positive tilt/orientation of this upper troughing and enhanced southwesterly flow aloft expected to persist through the period, a strong cold front should make only slow southeastward progress. A cap will likely inhibit surface-based convective development until peak afternoon heating and frontal forcing can help lift parcels to their LFC. Given nebulous forcing aloft, there is still a fair amount of uncertainty regarding overall convective coverage this afternoon/evening. Even so, any thunderstorms that can develop along or ahead of the front could pose a threat for severe hail and damaging winds, with strong deep-layer shear aiding updraft organization. This severe threat may persist for much of the evening, and perhaps continuing into the early overnight hours. ...Southern Plains to the Ozarks... The southern portion of the cold front is forecast to decelerate and eventually stall over parts of OK later today. A dryline will extend southward from a weak frontal low across northwest to west-central TX by late afternoon. Even with widespread mid/high-level cloudiness present, robust daytime heating of the moist warm sector is anticipated across the southern Plains today. The low-level cap should eventually be breached by late afternoon/early evening (around 22-00Z), particularly along/near the cold front, and perhaps the front/dryline intersection as well. Strong southwesterly flow aloft and related deep-layer shear will likely support organized severe convection. Initial supercell development should pose a threat for large to very large hail, potentially up to 2-3 inches in diameter. With time, upscale growth into multiple clusters/short line segments is expected through the evening into early Saturday morning, as a south-southwesterly low-level jet gradually strengthens. An increase in the severe/damaging wind threat is anticipated as this mode transition occurs. The threat for a few tornadoes remains apparent, especially across parts of OK along/south of the front, as favorable low-level shear will be present this evening where supercells may still exist. Even with a higher concentration of thunderstorms expected across the southern Plains, the messy convective mode this evening and tendency for convection to be undercut by the cold front currently limit confidence in delineating a corridor of greater severe hail/wind potential. ..Gleason/Broyles.. 04/18/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0700 AM CDT Fri Apr 18 2025 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE SOUTHERN PLAINS INTO THE MID MISSISSIPPI VALLEY AND UPPER GREAT LAKES... ...SUMMARY... Scattered severe thunderstorms are possible from parts of the southern Plains northeastward toward the upper Great Lakes, mainly from late afternoon into early Saturday morning. Large to very large hail and severe wind gusts should be the main hazards, especially across the southern Plains where storms will be more concentrated. A few tornadoes also appear possible. ...Upper Great Lakes to Mid Mississippi Valley... Ongoing, mostly elevated thunderstorms aided by persistent low-level warm/moist advection and steep mid-level lapse rates should continue to pose a large hail and damaging wind threat as they spread quickly eastward across southern WI this morning. This activity should eventually weaken later this morning as it continues moving across Lower MI into a less unstable environment. Behind this initial activity, the surface warm sector will attempt to spread northward across parts of the Upper Midwest and Great Lakes today, as longwave troughing gradually develops eastward over the northern/central Plains and Southwest. Given the positive tilt/orientation of this upper troughing and enhanced southwesterly flow aloft expected to persist through the period, a strong cold front should make only slow southeastward progress. A cap will likely inhibit surface-based convective development until peak afternoon heating and frontal forcing can help lift parcels to their LFC. Given nebulous forcing aloft, there is still a fair amount of uncertainty regarding overall convective coverage this afternoon/evening. Even so, any thunderstorms that can develop along or ahead of the front could pose a threat for severe hail and damaging winds, with strong deep-layer shear aiding updraft organization. This severe threat may persist for much of the evening, and perhaps continuing into the early overnight hours. ...Southern Plains to the Ozarks... The southern portion of the cold front is forecast to decelerate and eventually stall over parts of OK later today. A dryline will extend southward from a weak frontal low across northwest to west-central TX by late afternoon. Even with widespread mid/high-level cloudiness present, robust daytime heating of the moist warm sector is anticipated across the southern Plains today. The low-level cap should eventually be breached by late afternoon/early evening (around 22-00Z), particularly along/near the cold front, and perhaps the front/dryline intersection as well. Strong southwesterly flow aloft and related deep-layer shear will likely support organized severe convection. Initial supercell development should pose a threat for large to very large hail, potentially up to 2-3 inches in diameter. With time, upscale growth into multiple clusters/short line segments is expected through the evening into early Saturday morning, as a south-southwesterly low-level jet gradually strengthens. An increase in the severe/damaging wind threat is anticipated as this mode transition occurs. The threat for a few tornadoes remains apparent, especially across parts of OK along/south of the front, as favorable low-level shear will be present this evening where supercells may still exist. Even with a higher concentration of thunderstorms expected across the southern Plains, the messy convective mode this evening and tendency for convection to be undercut by the cold front currently limit confidence in delineating a corridor of greater severe hail/wind potential. ..Gleason/Broyles.. 04/18/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0700 AM CDT Fri Apr 18 2025 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE SOUTHERN PLAINS INTO THE MID MISSISSIPPI VALLEY AND UPPER GREAT LAKES... ...SUMMARY... Scattered severe thunderstorms are possible from parts of the southern Plains northeastward toward the upper Great Lakes, mainly from late afternoon into early Saturday morning. Large to very large hail and severe wind gusts should be the main hazards, especially across the southern Plains where storms will be more concentrated. A few tornadoes also appear possible. ...Upper Great Lakes to Mid Mississippi Valley... Ongoing, mostly elevated thunderstorms aided by persistent low-level warm/moist advection and steep mid-level lapse rates should continue to pose a large hail and damaging wind threat as they spread quickly eastward across southern WI this morning. This activity should eventually weaken later this morning as it continues moving across Lower MI into a less unstable environment. Behind this initial activity, the surface warm sector will attempt to spread northward across parts of the Upper Midwest and Great Lakes today, as longwave troughing gradually develops eastward over the northern/central Plains and Southwest. Given the positive tilt/orientation of this upper troughing and enhanced southwesterly flow aloft expected to persist through the period, a strong cold front should make only slow southeastward progress. A cap will likely inhibit surface-based convective development until peak afternoon heating and frontal forcing can help lift parcels to their LFC. Given nebulous forcing aloft, there is still a fair amount of uncertainty regarding overall convective coverage this afternoon/evening. Even so, any thunderstorms that can develop along or ahead of the front could pose a threat for severe hail and damaging winds, with strong deep-layer shear aiding updraft organization. This severe threat may persist for much of the evening, and perhaps continuing into the early overnight hours. ...Southern Plains to the Ozarks... The southern portion of the cold front is forecast to decelerate and eventually stall over parts of OK later today. A dryline will extend southward from a weak frontal low across northwest to west-central TX by late afternoon. Even with widespread mid/high-level cloudiness present, robust daytime heating of the moist warm sector is anticipated across the southern Plains today. The low-level cap should eventually be breached by late afternoon/early evening (around 22-00Z), particularly along/near the cold front, and perhaps the front/dryline intersection as well. Strong southwesterly flow aloft and related deep-layer shear will likely support organized severe convection. Initial supercell development should pose a threat for large to very large hail, potentially up to 2-3 inches in diameter. With time, upscale growth into multiple clusters/short line segments is expected through the evening into early Saturday morning, as a south-southwesterly low-level jet gradually strengthens. An increase in the severe/damaging wind threat is anticipated as this mode transition occurs. The threat for a few tornadoes remains apparent, especially across parts of OK along/south of the front, as favorable low-level shear will be present this evening where supercells may still exist. Even with a higher concentration of thunderstorms expected across the southern Plains, the messy convective mode this evening and tendency for convection to be undercut by the cold front currently limit confidence in delineating a corridor of greater severe hail/wind potential. ..Gleason/Broyles.. 04/18/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0700 AM CDT Fri Apr 18 2025 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE SOUTHERN PLAINS INTO THE MID MISSISSIPPI VALLEY AND UPPER GREAT LAKES... ...SUMMARY... Scattered severe thunderstorms are possible from parts of the southern Plains northeastward toward the upper Great Lakes, mainly from late afternoon into early Saturday morning. Large to very large hail and severe wind gusts should be the main hazards, especially across the southern Plains where storms will be more concentrated. A few tornadoes also appear possible. ...Upper Great Lakes to Mid Mississippi Valley... Ongoing, mostly elevated thunderstorms aided by persistent low-level warm/moist advection and steep mid-level lapse rates should continue to pose a large hail and damaging wind threat as they spread quickly eastward across southern WI this morning. This activity should eventually weaken later this morning as it continues moving across Lower MI into a less unstable environment. Behind this initial activity, the surface warm sector will attempt to spread northward across parts of the Upper Midwest and Great Lakes today, as longwave troughing gradually develops eastward over the northern/central Plains and Southwest. Given the positive tilt/orientation of this upper troughing and enhanced southwesterly flow aloft expected to persist through the period, a strong cold front should make only slow southeastward progress. A cap will likely inhibit surface-based convective development until peak afternoon heating and frontal forcing can help lift parcels to their LFC. Given nebulous forcing aloft, there is still a fair amount of uncertainty regarding overall convective coverage this afternoon/evening. Even so, any thunderstorms that can develop along or ahead of the front could pose a threat for severe hail and damaging winds, with strong deep-layer shear aiding updraft organization. This severe threat may persist for much of the evening, and perhaps continuing into the early overnight hours. ...Southern Plains to the Ozarks... The southern portion of the cold front is forecast to decelerate and eventually stall over parts of OK later today. A dryline will extend southward from a weak frontal low across northwest to west-central TX by late afternoon. Even with widespread mid/high-level cloudiness present, robust daytime heating of the moist warm sector is anticipated across the southern Plains today. The low-level cap should eventually be breached by late afternoon/early evening (around 22-00Z), particularly along/near the cold front, and perhaps the front/dryline intersection as well. Strong southwesterly flow aloft and related deep-layer shear will likely support organized severe convection. Initial supercell development should pose a threat for large to very large hail, potentially up to 2-3 inches in diameter. With time, upscale growth into multiple clusters/short line segments is expected through the evening into early Saturday morning, as a south-southwesterly low-level jet gradually strengthens. An increase in the severe/damaging wind threat is anticipated as this mode transition occurs. The threat for a few tornadoes remains apparent, especially across parts of OK along/south of the front, as favorable low-level shear will be present this evening where supercells may still exist. Even with a higher concentration of thunderstorms expected across the southern Plains, the messy convective mode this evening and tendency for convection to be undercut by the cold front currently limit confidence in delineating a corridor of greater severe hail/wind potential. ..Gleason/Broyles.. 04/18/2025 Read more

WW 0142 Status Updates
STATUS REPORT ON WW 142 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..BROYLES..04/18/25 ATTN...WFO...MKX... STATUS REPORT FOR WS 142 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS WIC021-025-027-045-049-055-059-065-079-089-101-105-127-131-133- 181240- WI . WISCONSIN COUNTIES INCLUDED ARE COLUMBIA DANE DODGE GREEN IOWA JEFFERSON KENOSHA LAFAYETTE MILWAUKEE OZAUKEE RACINE ROCK WALWORTH WASHINGTON WAUKESHA LMZ644-645-646-671-673-675-181240- CW . ADJACENT COASTAL WATERS INCLUDED ARE PORT WASHINGTON TO NORTH POINT LIGHT WI NORTH POINT LIGHT TO WIND POINT WI WIND POINT WI TO WINTHROP HARBOR IL LAKE MICHIGAN FROM PORT WASHINGTON TO NORTH POINT LIGHT WI 5NM Read more

WW 0142 Status Updates
STATUS FOR WATCH 0142 HAS NOT BEEN ISSUED YET Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0234 AM CDT Fri Apr 18 2025 Valid 211200Z - 261200Z ...DISCUSSION... An upper shortwave trough will weaken as it spreads east/northeast from the Mid/Upper MS Valley to the Lower Great Lakes on Day 4/Mon. The associated surface low will likewise shift northeast from eastern IA/IL into Ontario, while a trailing cold front moves across much of the Midwest. Modest boundary-layer moisture will aid in weak destabilization and some low-end severe thunderstorm risk could develop across parts of the Ohio Valley/Lower Great Lakes vicinity. The southern extent of this front will stall across the Mid-South and Sabine Valley. Richer low-level moisture ahead of the surface boundary across parts of the South could support some thunderstorm risk as well, but nebulous forcing and weak vertical shear will limit severe potential. On Days 5-8/Tue-Fri, a low-amplitude, weak flow pattern is forecast. Southerly low-level flow across the Gulf and southern Plains will allow for northward moisture transport across OK/TX and vicinity. Diurnal thunderstorm activity could be possible each day given modest west/southwest flow atop a moist warm sector. However, a rather nondescript surface pattern amid weak large-scale forcing will likely preclude widespread severe potential, though localized areas of severe storms could still occur given favorable moisture/instability, particularly along any dryline features. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0234 AM CDT Fri Apr 18 2025 Valid 211200Z - 261200Z ...DISCUSSION... An upper shortwave trough will weaken as it spreads east/northeast from the Mid/Upper MS Valley to the Lower Great Lakes on Day 4/Mon. The associated surface low will likewise shift northeast from eastern IA/IL into Ontario, while a trailing cold front moves across much of the Midwest. Modest boundary-layer moisture will aid in weak destabilization and some low-end severe thunderstorm risk could develop across parts of the Ohio Valley/Lower Great Lakes vicinity. The southern extent of this front will stall across the Mid-South and Sabine Valley. Richer low-level moisture ahead of the surface boundary across parts of the South could support some thunderstorm risk as well, but nebulous forcing and weak vertical shear will limit severe potential. On Days 5-8/Tue-Fri, a low-amplitude, weak flow pattern is forecast. Southerly low-level flow across the Gulf and southern Plains will allow for northward moisture transport across OK/TX and vicinity. Diurnal thunderstorm activity could be possible each day given modest west/southwest flow atop a moist warm sector. However, a rather nondescript surface pattern amid weak large-scale forcing will likely preclude widespread severe potential, though localized areas of severe storms could still occur given favorable moisture/instability, particularly along any dryline features. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0234 AM CDT Fri Apr 18 2025 Valid 211200Z - 261200Z ...DISCUSSION... An upper shortwave trough will weaken as it spreads east/northeast from the Mid/Upper MS Valley to the Lower Great Lakes on Day 4/Mon. The associated surface low will likewise shift northeast from eastern IA/IL into Ontario, while a trailing cold front moves across much of the Midwest. Modest boundary-layer moisture will aid in weak destabilization and some low-end severe thunderstorm risk could develop across parts of the Ohio Valley/Lower Great Lakes vicinity. The southern extent of this front will stall across the Mid-South and Sabine Valley. Richer low-level moisture ahead of the surface boundary across parts of the South could support some thunderstorm risk as well, but nebulous forcing and weak vertical shear will limit severe potential. On Days 5-8/Tue-Fri, a low-amplitude, weak flow pattern is forecast. Southerly low-level flow across the Gulf and southern Plains will allow for northward moisture transport across OK/TX and vicinity. Diurnal thunderstorm activity could be possible each day given modest west/southwest flow atop a moist warm sector. However, a rather nondescript surface pattern amid weak large-scale forcing will likely preclude widespread severe potential, though localized areas of severe storms could still occur given favorable moisture/instability, particularly along any dryline features. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0234 AM CDT Fri Apr 18 2025 Valid 211200Z - 261200Z ...DISCUSSION... An upper shortwave trough will weaken as it spreads east/northeast from the Mid/Upper MS Valley to the Lower Great Lakes on Day 4/Mon. The associated surface low will likewise shift northeast from eastern IA/IL into Ontario, while a trailing cold front moves across much of the Midwest. Modest boundary-layer moisture will aid in weak destabilization and some low-end severe thunderstorm risk could develop across parts of the Ohio Valley/Lower Great Lakes vicinity. The southern extent of this front will stall across the Mid-South and Sabine Valley. Richer low-level moisture ahead of the surface boundary across parts of the South could support some thunderstorm risk as well, but nebulous forcing and weak vertical shear will limit severe potential. On Days 5-8/Tue-Fri, a low-amplitude, weak flow pattern is forecast. Southerly low-level flow across the Gulf and southern Plains will allow for northward moisture transport across OK/TX and vicinity. Diurnal thunderstorm activity could be possible each day given modest west/southwest flow atop a moist warm sector. However, a rather nondescript surface pattern amid weak large-scale forcing will likely preclude widespread severe potential, though localized areas of severe storms could still occur given favorable moisture/instability, particularly along any dryline features. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0234 AM CDT Fri Apr 18 2025 Valid 211200Z - 261200Z ...DISCUSSION... An upper shortwave trough will weaken as it spreads east/northeast from the Mid/Upper MS Valley to the Lower Great Lakes on Day 4/Mon. The associated surface low will likewise shift northeast from eastern IA/IL into Ontario, while a trailing cold front moves across much of the Midwest. Modest boundary-layer moisture will aid in weak destabilization and some low-end severe thunderstorm risk could develop across parts of the Ohio Valley/Lower Great Lakes vicinity. The southern extent of this front will stall across the Mid-South and Sabine Valley. Richer low-level moisture ahead of the surface boundary across parts of the South could support some thunderstorm risk as well, but nebulous forcing and weak vertical shear will limit severe potential. On Days 5-8/Tue-Fri, a low-amplitude, weak flow pattern is forecast. Southerly low-level flow across the Gulf and southern Plains will allow for northward moisture transport across OK/TX and vicinity. Diurnal thunderstorm activity could be possible each day given modest west/southwest flow atop a moist warm sector. However, a rather nondescript surface pattern amid weak large-scale forcing will likely preclude widespread severe potential, though localized areas of severe storms could still occur given favorable moisture/instability, particularly along any dryline features. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0234 AM CDT Fri Apr 18 2025 Valid 211200Z - 261200Z ...DISCUSSION... An upper shortwave trough will weaken as it spreads east/northeast from the Mid/Upper MS Valley to the Lower Great Lakes on Day 4/Mon. The associated surface low will likewise shift northeast from eastern IA/IL into Ontario, while a trailing cold front moves across much of the Midwest. Modest boundary-layer moisture will aid in weak destabilization and some low-end severe thunderstorm risk could develop across parts of the Ohio Valley/Lower Great Lakes vicinity. The southern extent of this front will stall across the Mid-South and Sabine Valley. Richer low-level moisture ahead of the surface boundary across parts of the South could support some thunderstorm risk as well, but nebulous forcing and weak vertical shear will limit severe potential. On Days 5-8/Tue-Fri, a low-amplitude, weak flow pattern is forecast. Southerly low-level flow across the Gulf and southern Plains will allow for northward moisture transport across OK/TX and vicinity. Diurnal thunderstorm activity could be possible each day given modest west/southwest flow atop a moist warm sector. However, a rather nondescript surface pattern amid weak large-scale forcing will likely preclude widespread severe potential, though localized areas of severe storms could still occur given favorable moisture/instability, particularly along any dryline features. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0234 AM CDT Fri Apr 18 2025 Valid 211200Z - 261200Z ...DISCUSSION... An upper shortwave trough will weaken as it spreads east/northeast from the Mid/Upper MS Valley to the Lower Great Lakes on Day 4/Mon. The associated surface low will likewise shift northeast from eastern IA/IL into Ontario, while a trailing cold front moves across much of the Midwest. Modest boundary-layer moisture will aid in weak destabilization and some low-end severe thunderstorm risk could develop across parts of the Ohio Valley/Lower Great Lakes vicinity. The southern extent of this front will stall across the Mid-South and Sabine Valley. Richer low-level moisture ahead of the surface boundary across parts of the South could support some thunderstorm risk as well, but nebulous forcing and weak vertical shear will limit severe potential. On Days 5-8/Tue-Fri, a low-amplitude, weak flow pattern is forecast. Southerly low-level flow across the Gulf and southern Plains will allow for northward moisture transport across OK/TX and vicinity. Diurnal thunderstorm activity could be possible each day given modest west/southwest flow atop a moist warm sector. However, a rather nondescript surface pattern amid weak large-scale forcing will likely preclude widespread severe potential, though localized areas of severe storms could still occur given favorable moisture/instability, particularly along any dryline features. Read more