Severe Storms

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0458 PM CDT Sat Aug 16 2025 Valid 181200Z - 241200Z ...Day 3-5/Monday-Wednesday... An expanding and strengthening mid-level ridge over the Four Corners region will bring above normal temperatures but relatively light winds to much of the Intermountain West through the midweek. Mid-level troughing across the Pacific Northwest is expected to begin translating northeastward along the northern periphery of the ridge by Day 5/Wednesday, inviting drier conditions to filter into the Northwestern U.S. Ridge positioning will also usher in a northward surge of elevated monsoon moisture into the Desert Southwest by Day 4/Tuesday and by Day 5/Wednesday across the Eastern Great Basin. A dry boundary layer in place across the Four Corners and Great Basin regions will support limited rainfall from higher terrain convection and thunderstorms. Fuels are expected to remain quite dry and receptive across this region with a particular threat from new lightning ignitions. A 10 percent probability area for dry thunderstorms was introduced for Day 5/Wednesday. Farther north, the mid-level trough could support additional thunderstorms across portions of the central/northern ID and western MT Day 4-5/Tuesday-Wednesday but some uncertainty regarding antecedent rainfall distribution along with marginal fuel dryness precludes introduction of dry thunderstorm probabilities at this time. ...Day 6-8/Thursday-Saturday... Deeper monsoon moisture moving into Great Basin, with PWATs around 1.00 inch as well as rising surface dewpoints/relative humidity, should begin to limit dry lightning potential late in the week across the Great Basin and Four Corners regions with at least some wetting rains expected. Nonetheless, multiple days of higher terrain showers and thunderstorms will expand across much of the Intermountain West late next week. Lighter winds overall are expected under a building ridge over the Western U.S. along with steadily increasing temperatures, particularly across the western coastal states. A thermal trough begins to set up across CA late next week, further drying fuelscapes across the region as temperatures reach into the 100s in valley/interior locations. ..Williams.. 08/16/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0458 PM CDT Sat Aug 16 2025 Valid 181200Z - 241200Z ...Day 3-5/Monday-Wednesday... An expanding and strengthening mid-level ridge over the Four Corners region will bring above normal temperatures but relatively light winds to much of the Intermountain West through the midweek. Mid-level troughing across the Pacific Northwest is expected to begin translating northeastward along the northern periphery of the ridge by Day 5/Wednesday, inviting drier conditions to filter into the Northwestern U.S. Ridge positioning will also usher in a northward surge of elevated monsoon moisture into the Desert Southwest by Day 4/Tuesday and by Day 5/Wednesday across the Eastern Great Basin. A dry boundary layer in place across the Four Corners and Great Basin regions will support limited rainfall from higher terrain convection and thunderstorms. Fuels are expected to remain quite dry and receptive across this region with a particular threat from new lightning ignitions. A 10 percent probability area for dry thunderstorms was introduced for Day 5/Wednesday. Farther north, the mid-level trough could support additional thunderstorms across portions of the central/northern ID and western MT Day 4-5/Tuesday-Wednesday but some uncertainty regarding antecedent rainfall distribution along with marginal fuel dryness precludes introduction of dry thunderstorm probabilities at this time. ...Day 6-8/Thursday-Saturday... Deeper monsoon moisture moving into Great Basin, with PWATs around 1.00 inch as well as rising surface dewpoints/relative humidity, should begin to limit dry lightning potential late in the week across the Great Basin and Four Corners regions with at least some wetting rains expected. Nonetheless, multiple days of higher terrain showers and thunderstorms will expand across much of the Intermountain West late next week. Lighter winds overall are expected under a building ridge over the Western U.S. along with steadily increasing temperatures, particularly across the western coastal states. A thermal trough begins to set up across CA late next week, further drying fuelscapes across the region as temperatures reach into the 100s in valley/interior locations. ..Williams.. 08/16/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0458 PM CDT Sat Aug 16 2025 Valid 181200Z - 241200Z ...Day 3-5/Monday-Wednesday... An expanding and strengthening mid-level ridge over the Four Corners region will bring above normal temperatures but relatively light winds to much of the Intermountain West through the midweek. Mid-level troughing across the Pacific Northwest is expected to begin translating northeastward along the northern periphery of the ridge by Day 5/Wednesday, inviting drier conditions to filter into the Northwestern U.S. Ridge positioning will also usher in a northward surge of elevated monsoon moisture into the Desert Southwest by Day 4/Tuesday and by Day 5/Wednesday across the Eastern Great Basin. A dry boundary layer in place across the Four Corners and Great Basin regions will support limited rainfall from higher terrain convection and thunderstorms. Fuels are expected to remain quite dry and receptive across this region with a particular threat from new lightning ignitions. A 10 percent probability area for dry thunderstorms was introduced for Day 5/Wednesday. Farther north, the mid-level trough could support additional thunderstorms across portions of the central/northern ID and western MT Day 4-5/Tuesday-Wednesday but some uncertainty regarding antecedent rainfall distribution along with marginal fuel dryness precludes introduction of dry thunderstorm probabilities at this time. ...Day 6-8/Thursday-Saturday... Deeper monsoon moisture moving into Great Basin, with PWATs around 1.00 inch as well as rising surface dewpoints/relative humidity, should begin to limit dry lightning potential late in the week across the Great Basin and Four Corners regions with at least some wetting rains expected. Nonetheless, multiple days of higher terrain showers and thunderstorms will expand across much of the Intermountain West late next week. Lighter winds overall are expected under a building ridge over the Western U.S. along with steadily increasing temperatures, particularly across the western coastal states. A thermal trough begins to set up across CA late next week, further drying fuelscapes across the region as temperatures reach into the 100s in valley/interior locations. ..Williams.. 08/16/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0458 PM CDT Sat Aug 16 2025 Valid 181200Z - 241200Z ...Day 3-5/Monday-Wednesday... An expanding and strengthening mid-level ridge over the Four Corners region will bring above normal temperatures but relatively light winds to much of the Intermountain West through the midweek. Mid-level troughing across the Pacific Northwest is expected to begin translating northeastward along the northern periphery of the ridge by Day 5/Wednesday, inviting drier conditions to filter into the Northwestern U.S. Ridge positioning will also usher in a northward surge of elevated monsoon moisture into the Desert Southwest by Day 4/Tuesday and by Day 5/Wednesday across the Eastern Great Basin. A dry boundary layer in place across the Four Corners and Great Basin regions will support limited rainfall from higher terrain convection and thunderstorms. Fuels are expected to remain quite dry and receptive across this region with a particular threat from new lightning ignitions. A 10 percent probability area for dry thunderstorms was introduced for Day 5/Wednesday. Farther north, the mid-level trough could support additional thunderstorms across portions of the central/northern ID and western MT Day 4-5/Tuesday-Wednesday but some uncertainty regarding antecedent rainfall distribution along with marginal fuel dryness precludes introduction of dry thunderstorm probabilities at this time. ...Day 6-8/Thursday-Saturday... Deeper monsoon moisture moving into Great Basin, with PWATs around 1.00 inch as well as rising surface dewpoints/relative humidity, should begin to limit dry lightning potential late in the week across the Great Basin and Four Corners regions with at least some wetting rains expected. Nonetheless, multiple days of higher terrain showers and thunderstorms will expand across much of the Intermountain West late next week. Lighter winds overall are expected under a building ridge over the Western U.S. along with steadily increasing temperatures, particularly across the western coastal states. A thermal trough begins to set up across CA late next week, further drying fuelscapes across the region as temperatures reach into the 100s in valley/interior locations. ..Williams.. 08/16/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0458 PM CDT Sat Aug 16 2025 Valid 181200Z - 241200Z ...Day 3-5/Monday-Wednesday... An expanding and strengthening mid-level ridge over the Four Corners region will bring above normal temperatures but relatively light winds to much of the Intermountain West through the midweek. Mid-level troughing across the Pacific Northwest is expected to begin translating northeastward along the northern periphery of the ridge by Day 5/Wednesday, inviting drier conditions to filter into the Northwestern U.S. Ridge positioning will also usher in a northward surge of elevated monsoon moisture into the Desert Southwest by Day 4/Tuesday and by Day 5/Wednesday across the Eastern Great Basin. A dry boundary layer in place across the Four Corners and Great Basin regions will support limited rainfall from higher terrain convection and thunderstorms. Fuels are expected to remain quite dry and receptive across this region with a particular threat from new lightning ignitions. A 10 percent probability area for dry thunderstorms was introduced for Day 5/Wednesday. Farther north, the mid-level trough could support additional thunderstorms across portions of the central/northern ID and western MT Day 4-5/Tuesday-Wednesday but some uncertainty regarding antecedent rainfall distribution along with marginal fuel dryness precludes introduction of dry thunderstorm probabilities at this time. ...Day 6-8/Thursday-Saturday... Deeper monsoon moisture moving into Great Basin, with PWATs around 1.00 inch as well as rising surface dewpoints/relative humidity, should begin to limit dry lightning potential late in the week across the Great Basin and Four Corners regions with at least some wetting rains expected. Nonetheless, multiple days of higher terrain showers and thunderstorms will expand across much of the Intermountain West late next week. Lighter winds overall are expected under a building ridge over the Western U.S. along with steadily increasing temperatures, particularly across the western coastal states. A thermal trough begins to set up across CA late next week, further drying fuelscapes across the region as temperatures reach into the 100s in valley/interior locations. ..Williams.. 08/16/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0458 PM CDT Sat Aug 16 2025 Valid 181200Z - 241200Z ...Day 3-5/Monday-Wednesday... An expanding and strengthening mid-level ridge over the Four Corners region will bring above normal temperatures but relatively light winds to much of the Intermountain West through the midweek. Mid-level troughing across the Pacific Northwest is expected to begin translating northeastward along the northern periphery of the ridge by Day 5/Wednesday, inviting drier conditions to filter into the Northwestern U.S. Ridge positioning will also usher in a northward surge of elevated monsoon moisture into the Desert Southwest by Day 4/Tuesday and by Day 5/Wednesday across the Eastern Great Basin. A dry boundary layer in place across the Four Corners and Great Basin regions will support limited rainfall from higher terrain convection and thunderstorms. Fuels are expected to remain quite dry and receptive across this region with a particular threat from new lightning ignitions. A 10 percent probability area for dry thunderstorms was introduced for Day 5/Wednesday. Farther north, the mid-level trough could support additional thunderstorms across portions of the central/northern ID and western MT Day 4-5/Tuesday-Wednesday but some uncertainty regarding antecedent rainfall distribution along with marginal fuel dryness precludes introduction of dry thunderstorm probabilities at this time. ...Day 6-8/Thursday-Saturday... Deeper monsoon moisture moving into Great Basin, with PWATs around 1.00 inch as well as rising surface dewpoints/relative humidity, should begin to limit dry lightning potential late in the week across the Great Basin and Four Corners regions with at least some wetting rains expected. Nonetheless, multiple days of higher terrain showers and thunderstorms will expand across much of the Intermountain West late next week. Lighter winds overall are expected under a building ridge over the Western U.S. along with steadily increasing temperatures, particularly across the western coastal states. A thermal trough begins to set up across CA late next week, further drying fuelscapes across the region as temperatures reach into the 100s in valley/interior locations. ..Williams.. 08/16/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 1966 CONCERNING SEVERE THUNDERSTORM WATCH 596... FOR SOUTHEAST WISCONSIN...NORTHEAST ILLINOIS...AND NORTHWEST INDIANA
Mesoscale Discussion 1966 NWS Storm Prediction Center Norman OK 0234 PM CDT Sat Aug 16 2025 Areas affected...southeast Wisconsin...northeast Illinois...and northwest Indiana Concerning...Severe Thunderstorm Watch 596... Valid 161934Z - 162100Z The severe weather threat for Severe Thunderstorm Watch 596 continues. SUMMARY...The severe weather threat is increasing through the afternoon. DISCUSSION...A cluster of supercells has developed across central Minnesota. The MKX VWP is sampling around 45 knots of mid-level flow which is resulting in around 40 knots of effective shear. Shear decreases rapidly with southern extent to only around 15 to 20 knots across northern Illinois. Therefore, storms may become less organized and outflow dominant as they congeal and move south across northern Illinois. However, greater instability (3000-4000 J/kg MLCAPE) and near 2 inch PWAT values will support a damaging wind threat as the storm cluster moves south this afternoon and evening. ..Bentley/Mosier.. 08/16/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...IWX...LOT...MKX...DVN... LAT...LON 42908961 43088920 43088827 42948766 42628728 42018704 41668691 41358689 41178707 41188772 41328848 41568885 42068936 42388951 42908961 MOST PROBABLE PEAK WIND GUST...55-70 MPH MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN Read more

WW 0596 Status Updates
STATUS REPORT ON WW 596 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..BENTLEY..08/16/25 ATTN...WFO...LOT...DVN...MKX... STATUS REPORT FOR WS 596 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC007-031-037-043-089-093-097-111-141-177-197-201-162140- IL . ILLINOIS COUNTIES INCLUDED ARE BOONE COOK DE KALB DUPAGE KANE KENDALL LAKE MCHENRY OGLE STEPHENSON WILL WINNEBAGO INC089-127-162140- IN . INDIANA COUNTIES INCLUDED ARE LAKE PORTER WIC021-025-027-039-045-047-049-055-059-065-077-079-101-105-111- 127-133-162140- WI . WISCONSIN COUNTIES INCLUDED ARE COLUMBIA DANE DODGE Read more

WW 0596 Status Updates
STATUS REPORT ON WW 596 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..BENTLEY..08/16/25 ATTN...WFO...LOT...DVN...MKX... STATUS REPORT FOR WS 596 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC007-031-037-043-089-093-097-111-141-177-197-201-162140- IL . ILLINOIS COUNTIES INCLUDED ARE BOONE COOK DE KALB DUPAGE KANE KENDALL LAKE MCHENRY OGLE STEPHENSON WILL WINNEBAGO INC089-127-162140- IN . INDIANA COUNTIES INCLUDED ARE LAKE PORTER WIC021-025-027-039-045-047-049-055-059-065-077-079-101-105-111- 127-133-162140- WI . WISCONSIN COUNTIES INCLUDED ARE COLUMBIA DANE DODGE Read more

MD 1965 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR NORTHEAST IOWA...SOUTHEAST MINNESOTA AND WESTERN WISCONSIN.
Mesoscale Discussion 1965 NWS Storm Prediction Center Norman OK 0205 PM CDT Sat Aug 16 2025 Areas affected...northeast Iowa...southeast Minnesota and western Wisconsin. Concerning...Severe potential...Watch unlikely Valid 161905Z - 162030Z Probability of Watch Issuance...20 percent SUMMARY...Isolated severe storms are possible this afternoon/evening. No watch is anticipated. DISCUSSION...A cluster of storms has developed across southeast Minnesota and western Wisconsin in the wake of the morning MCS. These elevated storms are in a region with strong shear (50+ knots per ARX VWP), but are somewhat removed from the better elevated instability according to SPC mesoanalysis. Therefore, the current location and storm motion favoring movement farther into the cold air would suggest severe potential may be somewhat limited from this activity. If additional storms can develop farther south (across northeast Iowa), they may pose a greater severe potential, but visible satellite trends do not support an imminent threat of additional development in this area. ..Bentley.. 08/16/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GRB...MKX...ARX...MPX...DMX... LAT...LON 44409206 44419092 44719027 44718994 44388950 43798922 43368939 43099022 42889121 42889230 43059311 43529328 44409206 MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 16 2025 Valid 162000Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PART OF SD...AND THIS AFTERNOON THROUGH TONIGHT OVER SOUTHEAST MN...SOUTHERN WI...AND NORTHERN IL... ...SUMMARY... Scattered strong/severe thunderstorms are possible today into tonight across parts of the northern Great Plains into the Midwest and Great Lakes regions. ...20Z Update... The prior forecast reasoning remains valid. Severe probabilities were reduced in parts of northern/central Wisconsin where prior convection has stabilized the boundary layer. Elsewhere, only minor changes were made to the general thunderstorm forecast based on current observational trends. See the previous discussion as well as MCDs 1965/1966 for additional information. ..Wendt.. 08/16/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 16 2025/ ...Upper Midwest into the Mid MS Valley and Upper Great Lakes Region... An expansive MCS continues to move eastward across the Upper Midwest, with a well-defined MCV evident in radar imagery over the central WI/MN border vicinity. This MCS has continued to gradually weaken throughout the morning, but a few strong updrafts persist along its southeastern periphery over central WI. This portion of the MCS is on the far northeastern periphery of the plume of steeper mid-level lapse rates that extends from the northern/central High Plains across the central Plains and into the Mid MS Valley. This plume is observable in the 12Z sounding from DVN and ILX, which sampled 700-500 mb lapse rates of 7.8 and 7.2 deg C per km, respectively. Dewpoints downstream across southern WI, northern IL, and northern IN are in the low 70s, with upper 60s dewpoints also covering much of southern Lower MI. The combination of ample low-level moisture and steep mid-level lapse rates will result in strong to very strong buoyancy to the south of the MCS from the MN/IA border into northern/central IL. Given the lack of a well-defined surface boundary and negligible large-scale ascent, additional thunderstorm development will be associated with outflow from with the MCS, which results in greater-than-average uncertainty for the Day 1 period. Ample moisture and buoyancy downstream of the leading edge of the MCS suggests the greater severe potential this afternoon/evening will likely be associated with redevelopment/reintensification of the MCS. Additionally, even if reintensification does not occur along the leading edge of the MCS this afternoon, most guidance suggests redevelopment does eventually occur this evening along the southern periphery of the MCV circulation as it moves into northern/central WI. Increased severe-wind probabilities (i.e. 15%) were introduced with this outlook to cover both of these potential scenarios. A small 15% hail probability was introduce to cover potential for later evening storms atop the outflow as well. Storms are possible into northern IN and the Lower MI this afternoon and evening as well, but the lower buoyancy should temper the overall coverage and magnitude in these areas. ...SD and Vicinity... A well-defined but rather weak shortwave trough is currently moving through western CO/western WY, and will continue northeastward into eastern WY/western Dakotas by this evening. Similar to yesterday, high-based storms will develop ahead of the approaching shortwave and intensify as they move eastward into a progressively more moist/unstable air mass over west-central SD. Upscale growth into another nocturnal MCS is forecast by most guidance, with the MCS tracking northeastward across western/central SD tonight. Strong to severe gusts are possible with this potential MCS across much of western/central SD. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 16 2025 Valid 162000Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PART OF SD...AND THIS AFTERNOON THROUGH TONIGHT OVER SOUTHEAST MN...SOUTHERN WI...AND NORTHERN IL... ...SUMMARY... Scattered strong/severe thunderstorms are possible today into tonight across parts of the northern Great Plains into the Midwest and Great Lakes regions. ...20Z Update... The prior forecast reasoning remains valid. Severe probabilities were reduced in parts of northern/central Wisconsin where prior convection has stabilized the boundary layer. Elsewhere, only minor changes were made to the general thunderstorm forecast based on current observational trends. See the previous discussion as well as MCDs 1965/1966 for additional information. ..Wendt.. 08/16/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 16 2025/ ...Upper Midwest into the Mid MS Valley and Upper Great Lakes Region... An expansive MCS continues to move eastward across the Upper Midwest, with a well-defined MCV evident in radar imagery over the central WI/MN border vicinity. This MCS has continued to gradually weaken throughout the morning, but a few strong updrafts persist along its southeastern periphery over central WI. This portion of the MCS is on the far northeastern periphery of the plume of steeper mid-level lapse rates that extends from the northern/central High Plains across the central Plains and into the Mid MS Valley. This plume is observable in the 12Z sounding from DVN and ILX, which sampled 700-500 mb lapse rates of 7.8 and 7.2 deg C per km, respectively. Dewpoints downstream across southern WI, northern IL, and northern IN are in the low 70s, with upper 60s dewpoints also covering much of southern Lower MI. The combination of ample low-level moisture and steep mid-level lapse rates will result in strong to very strong buoyancy to the south of the MCS from the MN/IA border into northern/central IL. Given the lack of a well-defined surface boundary and negligible large-scale ascent, additional thunderstorm development will be associated with outflow from with the MCS, which results in greater-than-average uncertainty for the Day 1 period. Ample moisture and buoyancy downstream of the leading edge of the MCS suggests the greater severe potential this afternoon/evening will likely be associated with redevelopment/reintensification of the MCS. Additionally, even if reintensification does not occur along the leading edge of the MCS this afternoon, most guidance suggests redevelopment does eventually occur this evening along the southern periphery of the MCV circulation as it moves into northern/central WI. Increased severe-wind probabilities (i.e. 15%) were introduced with this outlook to cover both of these potential scenarios. A small 15% hail probability was introduce to cover potential for later evening storms atop the outflow as well. Storms are possible into northern IN and the Lower MI this afternoon and evening as well, but the lower buoyancy should temper the overall coverage and magnitude in these areas. ...SD and Vicinity... A well-defined but rather weak shortwave trough is currently moving through western CO/western WY, and will continue northeastward into eastern WY/western Dakotas by this evening. Similar to yesterday, high-based storms will develop ahead of the approaching shortwave and intensify as they move eastward into a progressively more moist/unstable air mass over west-central SD. Upscale growth into another nocturnal MCS is forecast by most guidance, with the MCS tracking northeastward across western/central SD tonight. Strong to severe gusts are possible with this potential MCS across much of western/central SD. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 16 2025 Valid 162000Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PART OF SD...AND THIS AFTERNOON THROUGH TONIGHT OVER SOUTHEAST MN...SOUTHERN WI...AND NORTHERN IL... ...SUMMARY... Scattered strong/severe thunderstorms are possible today into tonight across parts of the northern Great Plains into the Midwest and Great Lakes regions. ...20Z Update... The prior forecast reasoning remains valid. Severe probabilities were reduced in parts of northern/central Wisconsin where prior convection has stabilized the boundary layer. Elsewhere, only minor changes were made to the general thunderstorm forecast based on current observational trends. See the previous discussion as well as MCDs 1965/1966 for additional information. ..Wendt.. 08/16/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 16 2025/ ...Upper Midwest into the Mid MS Valley and Upper Great Lakes Region... An expansive MCS continues to move eastward across the Upper Midwest, with a well-defined MCV evident in radar imagery over the central WI/MN border vicinity. This MCS has continued to gradually weaken throughout the morning, but a few strong updrafts persist along its southeastern periphery over central WI. This portion of the MCS is on the far northeastern periphery of the plume of steeper mid-level lapse rates that extends from the northern/central High Plains across the central Plains and into the Mid MS Valley. This plume is observable in the 12Z sounding from DVN and ILX, which sampled 700-500 mb lapse rates of 7.8 and 7.2 deg C per km, respectively. Dewpoints downstream across southern WI, northern IL, and northern IN are in the low 70s, with upper 60s dewpoints also covering much of southern Lower MI. The combination of ample low-level moisture and steep mid-level lapse rates will result in strong to very strong buoyancy to the south of the MCS from the MN/IA border into northern/central IL. Given the lack of a well-defined surface boundary and negligible large-scale ascent, additional thunderstorm development will be associated with outflow from with the MCS, which results in greater-than-average uncertainty for the Day 1 period. Ample moisture and buoyancy downstream of the leading edge of the MCS suggests the greater severe potential this afternoon/evening will likely be associated with redevelopment/reintensification of the MCS. Additionally, even if reintensification does not occur along the leading edge of the MCS this afternoon, most guidance suggests redevelopment does eventually occur this evening along the southern periphery of the MCV circulation as it moves into northern/central WI. Increased severe-wind probabilities (i.e. 15%) were introduced with this outlook to cover both of these potential scenarios. A small 15% hail probability was introduce to cover potential for later evening storms atop the outflow as well. Storms are possible into northern IN and the Lower MI this afternoon and evening as well, but the lower buoyancy should temper the overall coverage and magnitude in these areas. ...SD and Vicinity... A well-defined but rather weak shortwave trough is currently moving through western CO/western WY, and will continue northeastward into eastern WY/western Dakotas by this evening. Similar to yesterday, high-based storms will develop ahead of the approaching shortwave and intensify as they move eastward into a progressively more moist/unstable air mass over west-central SD. Upscale growth into another nocturnal MCS is forecast by most guidance, with the MCS tracking northeastward across western/central SD tonight. Strong to severe gusts are possible with this potential MCS across much of western/central SD. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 16 2025 Valid 162000Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PART OF SD...AND THIS AFTERNOON THROUGH TONIGHT OVER SOUTHEAST MN...SOUTHERN WI...AND NORTHERN IL... ...SUMMARY... Scattered strong/severe thunderstorms are possible today into tonight across parts of the northern Great Plains into the Midwest and Great Lakes regions. ...20Z Update... The prior forecast reasoning remains valid. Severe probabilities were reduced in parts of northern/central Wisconsin where prior convection has stabilized the boundary layer. Elsewhere, only minor changes were made to the general thunderstorm forecast based on current observational trends. See the previous discussion as well as MCDs 1965/1966 for additional information. ..Wendt.. 08/16/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 16 2025/ ...Upper Midwest into the Mid MS Valley and Upper Great Lakes Region... An expansive MCS continues to move eastward across the Upper Midwest, with a well-defined MCV evident in radar imagery over the central WI/MN border vicinity. This MCS has continued to gradually weaken throughout the morning, but a few strong updrafts persist along its southeastern periphery over central WI. This portion of the MCS is on the far northeastern periphery of the plume of steeper mid-level lapse rates that extends from the northern/central High Plains across the central Plains and into the Mid MS Valley. This plume is observable in the 12Z sounding from DVN and ILX, which sampled 700-500 mb lapse rates of 7.8 and 7.2 deg C per km, respectively. Dewpoints downstream across southern WI, northern IL, and northern IN are in the low 70s, with upper 60s dewpoints also covering much of southern Lower MI. The combination of ample low-level moisture and steep mid-level lapse rates will result in strong to very strong buoyancy to the south of the MCS from the MN/IA border into northern/central IL. Given the lack of a well-defined surface boundary and negligible large-scale ascent, additional thunderstorm development will be associated with outflow from with the MCS, which results in greater-than-average uncertainty for the Day 1 period. Ample moisture and buoyancy downstream of the leading edge of the MCS suggests the greater severe potential this afternoon/evening will likely be associated with redevelopment/reintensification of the MCS. Additionally, even if reintensification does not occur along the leading edge of the MCS this afternoon, most guidance suggests redevelopment does eventually occur this evening along the southern periphery of the MCV circulation as it moves into northern/central WI. Increased severe-wind probabilities (i.e. 15%) were introduced with this outlook to cover both of these potential scenarios. A small 15% hail probability was introduce to cover potential for later evening storms atop the outflow as well. Storms are possible into northern IN and the Lower MI this afternoon and evening as well, but the lower buoyancy should temper the overall coverage and magnitude in these areas. ...SD and Vicinity... A well-defined but rather weak shortwave trough is currently moving through western CO/western WY, and will continue northeastward into eastern WY/western Dakotas by this evening. Similar to yesterday, high-based storms will develop ahead of the approaching shortwave and intensify as they move eastward into a progressively more moist/unstable air mass over west-central SD. Upscale growth into another nocturnal MCS is forecast by most guidance, with the MCS tracking northeastward across western/central SD tonight. Strong to severe gusts are possible with this potential MCS across much of western/central SD. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 16 2025 Valid 162000Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PART OF SD...AND THIS AFTERNOON THROUGH TONIGHT OVER SOUTHEAST MN...SOUTHERN WI...AND NORTHERN IL... ...SUMMARY... Scattered strong/severe thunderstorms are possible today into tonight across parts of the northern Great Plains into the Midwest and Great Lakes regions. ...20Z Update... The prior forecast reasoning remains valid. Severe probabilities were reduced in parts of northern/central Wisconsin where prior convection has stabilized the boundary layer. Elsewhere, only minor changes were made to the general thunderstorm forecast based on current observational trends. See the previous discussion as well as MCDs 1965/1966 for additional information. ..Wendt.. 08/16/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 16 2025/ ...Upper Midwest into the Mid MS Valley and Upper Great Lakes Region... An expansive MCS continues to move eastward across the Upper Midwest, with a well-defined MCV evident in radar imagery over the central WI/MN border vicinity. This MCS has continued to gradually weaken throughout the morning, but a few strong updrafts persist along its southeastern periphery over central WI. This portion of the MCS is on the far northeastern periphery of the plume of steeper mid-level lapse rates that extends from the northern/central High Plains across the central Plains and into the Mid MS Valley. This plume is observable in the 12Z sounding from DVN and ILX, which sampled 700-500 mb lapse rates of 7.8 and 7.2 deg C per km, respectively. Dewpoints downstream across southern WI, northern IL, and northern IN are in the low 70s, with upper 60s dewpoints also covering much of southern Lower MI. The combination of ample low-level moisture and steep mid-level lapse rates will result in strong to very strong buoyancy to the south of the MCS from the MN/IA border into northern/central IL. Given the lack of a well-defined surface boundary and negligible large-scale ascent, additional thunderstorm development will be associated with outflow from with the MCS, which results in greater-than-average uncertainty for the Day 1 period. Ample moisture and buoyancy downstream of the leading edge of the MCS suggests the greater severe potential this afternoon/evening will likely be associated with redevelopment/reintensification of the MCS. Additionally, even if reintensification does not occur along the leading edge of the MCS this afternoon, most guidance suggests redevelopment does eventually occur this evening along the southern periphery of the MCV circulation as it moves into northern/central WI. Increased severe-wind probabilities (i.e. 15%) were introduced with this outlook to cover both of these potential scenarios. A small 15% hail probability was introduce to cover potential for later evening storms atop the outflow as well. Storms are possible into northern IN and the Lower MI this afternoon and evening as well, but the lower buoyancy should temper the overall coverage and magnitude in these areas. ...SD and Vicinity... A well-defined but rather weak shortwave trough is currently moving through western CO/western WY, and will continue northeastward into eastern WY/western Dakotas by this evening. Similar to yesterday, high-based storms will develop ahead of the approaching shortwave and intensify as they move eastward into a progressively more moist/unstable air mass over west-central SD. Upscale growth into another nocturnal MCS is forecast by most guidance, with the MCS tracking northeastward across western/central SD tonight. Strong to severe gusts are possible with this potential MCS across much of western/central SD. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 16 2025 Valid 162000Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PART OF SD...AND THIS AFTERNOON THROUGH TONIGHT OVER SOUTHEAST MN...SOUTHERN WI...AND NORTHERN IL... ...SUMMARY... Scattered strong/severe thunderstorms are possible today into tonight across parts of the northern Great Plains into the Midwest and Great Lakes regions. ...20Z Update... The prior forecast reasoning remains valid. Severe probabilities were reduced in parts of northern/central Wisconsin where prior convection has stabilized the boundary layer. Elsewhere, only minor changes were made to the general thunderstorm forecast based on current observational trends. See the previous discussion as well as MCDs 1965/1966 for additional information. ..Wendt.. 08/16/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 16 2025/ ...Upper Midwest into the Mid MS Valley and Upper Great Lakes Region... An expansive MCS continues to move eastward across the Upper Midwest, with a well-defined MCV evident in radar imagery over the central WI/MN border vicinity. This MCS has continued to gradually weaken throughout the morning, but a few strong updrafts persist along its southeastern periphery over central WI. This portion of the MCS is on the far northeastern periphery of the plume of steeper mid-level lapse rates that extends from the northern/central High Plains across the central Plains and into the Mid MS Valley. This plume is observable in the 12Z sounding from DVN and ILX, which sampled 700-500 mb lapse rates of 7.8 and 7.2 deg C per km, respectively. Dewpoints downstream across southern WI, northern IL, and northern IN are in the low 70s, with upper 60s dewpoints also covering much of southern Lower MI. The combination of ample low-level moisture and steep mid-level lapse rates will result in strong to very strong buoyancy to the south of the MCS from the MN/IA border into northern/central IL. Given the lack of a well-defined surface boundary and negligible large-scale ascent, additional thunderstorm development will be associated with outflow from with the MCS, which results in greater-than-average uncertainty for the Day 1 period. Ample moisture and buoyancy downstream of the leading edge of the MCS suggests the greater severe potential this afternoon/evening will likely be associated with redevelopment/reintensification of the MCS. Additionally, even if reintensification does not occur along the leading edge of the MCS this afternoon, most guidance suggests redevelopment does eventually occur this evening along the southern periphery of the MCV circulation as it moves into northern/central WI. Increased severe-wind probabilities (i.e. 15%) were introduced with this outlook to cover both of these potential scenarios. A small 15% hail probability was introduce to cover potential for later evening storms atop the outflow as well. Storms are possible into northern IN and the Lower MI this afternoon and evening as well, but the lower buoyancy should temper the overall coverage and magnitude in these areas. ...SD and Vicinity... A well-defined but rather weak shortwave trough is currently moving through western CO/western WY, and will continue northeastward into eastern WY/western Dakotas by this evening. Similar to yesterday, high-based storms will develop ahead of the approaching shortwave and intensify as they move eastward into a progressively more moist/unstable air mass over west-central SD. Upscale growth into another nocturnal MCS is forecast by most guidance, with the MCS tracking northeastward across western/central SD tonight. Strong to severe gusts are possible with this potential MCS across much of western/central SD. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 16 2025 Valid 162000Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PART OF SD...AND THIS AFTERNOON THROUGH TONIGHT OVER SOUTHEAST MN...SOUTHERN WI...AND NORTHERN IL... ...SUMMARY... Scattered strong/severe thunderstorms are possible today into tonight across parts of the northern Great Plains into the Midwest and Great Lakes regions. ...20Z Update... The prior forecast reasoning remains valid. Severe probabilities were reduced in parts of northern/central Wisconsin where prior convection has stabilized the boundary layer. Elsewhere, only minor changes were made to the general thunderstorm forecast based on current observational trends. See the previous discussion as well as MCDs 1965/1966 for additional information. ..Wendt.. 08/16/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 16 2025/ ...Upper Midwest into the Mid MS Valley and Upper Great Lakes Region... An expansive MCS continues to move eastward across the Upper Midwest, with a well-defined MCV evident in radar imagery over the central WI/MN border vicinity. This MCS has continued to gradually weaken throughout the morning, but a few strong updrafts persist along its southeastern periphery over central WI. This portion of the MCS is on the far northeastern periphery of the plume of steeper mid-level lapse rates that extends from the northern/central High Plains across the central Plains and into the Mid MS Valley. This plume is observable in the 12Z sounding from DVN and ILX, which sampled 700-500 mb lapse rates of 7.8 and 7.2 deg C per km, respectively. Dewpoints downstream across southern WI, northern IL, and northern IN are in the low 70s, with upper 60s dewpoints also covering much of southern Lower MI. The combination of ample low-level moisture and steep mid-level lapse rates will result in strong to very strong buoyancy to the south of the MCS from the MN/IA border into northern/central IL. Given the lack of a well-defined surface boundary and negligible large-scale ascent, additional thunderstorm development will be associated with outflow from with the MCS, which results in greater-than-average uncertainty for the Day 1 period. Ample moisture and buoyancy downstream of the leading edge of the MCS suggests the greater severe potential this afternoon/evening will likely be associated with redevelopment/reintensification of the MCS. Additionally, even if reintensification does not occur along the leading edge of the MCS this afternoon, most guidance suggests redevelopment does eventually occur this evening along the southern periphery of the MCV circulation as it moves into northern/central WI. Increased severe-wind probabilities (i.e. 15%) were introduced with this outlook to cover both of these potential scenarios. A small 15% hail probability was introduce to cover potential for later evening storms atop the outflow as well. Storms are possible into northern IN and the Lower MI this afternoon and evening as well, but the lower buoyancy should temper the overall coverage and magnitude in these areas. ...SD and Vicinity... A well-defined but rather weak shortwave trough is currently moving through western CO/western WY, and will continue northeastward into eastern WY/western Dakotas by this evening. Similar to yesterday, high-based storms will develop ahead of the approaching shortwave and intensify as they move eastward into a progressively more moist/unstable air mass over west-central SD. Upscale growth into another nocturnal MCS is forecast by most guidance, with the MCS tracking northeastward across western/central SD tonight. Strong to severe gusts are possible with this potential MCS across much of western/central SD. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 16 2025 Valid 162000Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PART OF SD...AND THIS AFTERNOON THROUGH TONIGHT OVER SOUTHEAST MN...SOUTHERN WI...AND NORTHERN IL... ...SUMMARY... Scattered strong/severe thunderstorms are possible today into tonight across parts of the northern Great Plains into the Midwest and Great Lakes regions. ...20Z Update... The prior forecast reasoning remains valid. Severe probabilities were reduced in parts of northern/central Wisconsin where prior convection has stabilized the boundary layer. Elsewhere, only minor changes were made to the general thunderstorm forecast based on current observational trends. See the previous discussion as well as MCDs 1965/1966 for additional information. ..Wendt.. 08/16/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 16 2025/ ...Upper Midwest into the Mid MS Valley and Upper Great Lakes Region... An expansive MCS continues to move eastward across the Upper Midwest, with a well-defined MCV evident in radar imagery over the central WI/MN border vicinity. This MCS has continued to gradually weaken throughout the morning, but a few strong updrafts persist along its southeastern periphery over central WI. This portion of the MCS is on the far northeastern periphery of the plume of steeper mid-level lapse rates that extends from the northern/central High Plains across the central Plains and into the Mid MS Valley. This plume is observable in the 12Z sounding from DVN and ILX, which sampled 700-500 mb lapse rates of 7.8 and 7.2 deg C per km, respectively. Dewpoints downstream across southern WI, northern IL, and northern IN are in the low 70s, with upper 60s dewpoints also covering much of southern Lower MI. The combination of ample low-level moisture and steep mid-level lapse rates will result in strong to very strong buoyancy to the south of the MCS from the MN/IA border into northern/central IL. Given the lack of a well-defined surface boundary and negligible large-scale ascent, additional thunderstorm development will be associated with outflow from with the MCS, which results in greater-than-average uncertainty for the Day 1 period. Ample moisture and buoyancy downstream of the leading edge of the MCS suggests the greater severe potential this afternoon/evening will likely be associated with redevelopment/reintensification of the MCS. Additionally, even if reintensification does not occur along the leading edge of the MCS this afternoon, most guidance suggests redevelopment does eventually occur this evening along the southern periphery of the MCV circulation as it moves into northern/central WI. Increased severe-wind probabilities (i.e. 15%) were introduced with this outlook to cover both of these potential scenarios. A small 15% hail probability was introduce to cover potential for later evening storms atop the outflow as well. Storms are possible into northern IN and the Lower MI this afternoon and evening as well, but the lower buoyancy should temper the overall coverage and magnitude in these areas. ...SD and Vicinity... A well-defined but rather weak shortwave trough is currently moving through western CO/western WY, and will continue northeastward into eastern WY/western Dakotas by this evening. Similar to yesterday, high-based storms will develop ahead of the approaching shortwave and intensify as they move eastward into a progressively more moist/unstable air mass over west-central SD. Upscale growth into another nocturnal MCS is forecast by most guidance, with the MCS tracking northeastward across western/central SD tonight. Strong to severe gusts are possible with this potential MCS across much of western/central SD. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 16 2025 Valid 162000Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PART OF SD...AND THIS AFTERNOON THROUGH TONIGHT OVER SOUTHEAST MN...SOUTHERN WI...AND NORTHERN IL... ...SUMMARY... Scattered strong/severe thunderstorms are possible today into tonight across parts of the northern Great Plains into the Midwest and Great Lakes regions. ...20Z Update... The prior forecast reasoning remains valid. Severe probabilities were reduced in parts of northern/central Wisconsin where prior convection has stabilized the boundary layer. Elsewhere, only minor changes were made to the general thunderstorm forecast based on current observational trends. See the previous discussion as well as MCDs 1965/1966 for additional information. ..Wendt.. 08/16/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 16 2025/ ...Upper Midwest into the Mid MS Valley and Upper Great Lakes Region... An expansive MCS continues to move eastward across the Upper Midwest, with a well-defined MCV evident in radar imagery over the central WI/MN border vicinity. This MCS has continued to gradually weaken throughout the morning, but a few strong updrafts persist along its southeastern periphery over central WI. This portion of the MCS is on the far northeastern periphery of the plume of steeper mid-level lapse rates that extends from the northern/central High Plains across the central Plains and into the Mid MS Valley. This plume is observable in the 12Z sounding from DVN and ILX, which sampled 700-500 mb lapse rates of 7.8 and 7.2 deg C per km, respectively. Dewpoints downstream across southern WI, northern IL, and northern IN are in the low 70s, with upper 60s dewpoints also covering much of southern Lower MI. The combination of ample low-level moisture and steep mid-level lapse rates will result in strong to very strong buoyancy to the south of the MCS from the MN/IA border into northern/central IL. Given the lack of a well-defined surface boundary and negligible large-scale ascent, additional thunderstorm development will be associated with outflow from with the MCS, which results in greater-than-average uncertainty for the Day 1 period. Ample moisture and buoyancy downstream of the leading edge of the MCS suggests the greater severe potential this afternoon/evening will likely be associated with redevelopment/reintensification of the MCS. Additionally, even if reintensification does not occur along the leading edge of the MCS this afternoon, most guidance suggests redevelopment does eventually occur this evening along the southern periphery of the MCV circulation as it moves into northern/central WI. Increased severe-wind probabilities (i.e. 15%) were introduced with this outlook to cover both of these potential scenarios. A small 15% hail probability was introduce to cover potential for later evening storms atop the outflow as well. Storms are possible into northern IN and the Lower MI this afternoon and evening as well, but the lower buoyancy should temper the overall coverage and magnitude in these areas. ...SD and Vicinity... A well-defined but rather weak shortwave trough is currently moving through western CO/western WY, and will continue northeastward into eastern WY/western Dakotas by this evening. Similar to yesterday, high-based storms will develop ahead of the approaching shortwave and intensify as they move eastward into a progressively more moist/unstable air mass over west-central SD. Upscale growth into another nocturnal MCS is forecast by most guidance, with the MCS tracking northeastward across western/central SD tonight. Strong to severe gusts are possible with this potential MCS across much of western/central SD. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 16 2025 Valid 162000Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PART OF SD...AND THIS AFTERNOON THROUGH TONIGHT OVER SOUTHEAST MN...SOUTHERN WI...AND NORTHERN IL... ...SUMMARY... Scattered strong/severe thunderstorms are possible today into tonight across parts of the northern Great Plains into the Midwest and Great Lakes regions. ...20Z Update... The prior forecast reasoning remains valid. Severe probabilities were reduced in parts of northern/central Wisconsin where prior convection has stabilized the boundary layer. Elsewhere, only minor changes were made to the general thunderstorm forecast based on current observational trends. See the previous discussion as well as MCDs 1965/1966 for additional information. ..Wendt.. 08/16/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 16 2025/ ...Upper Midwest into the Mid MS Valley and Upper Great Lakes Region... An expansive MCS continues to move eastward across the Upper Midwest, with a well-defined MCV evident in radar imagery over the central WI/MN border vicinity. This MCS has continued to gradually weaken throughout the morning, but a few strong updrafts persist along its southeastern periphery over central WI. This portion of the MCS is on the far northeastern periphery of the plume of steeper mid-level lapse rates that extends from the northern/central High Plains across the central Plains and into the Mid MS Valley. This plume is observable in the 12Z sounding from DVN and ILX, which sampled 700-500 mb lapse rates of 7.8 and 7.2 deg C per km, respectively. Dewpoints downstream across southern WI, northern IL, and northern IN are in the low 70s, with upper 60s dewpoints also covering much of southern Lower MI. The combination of ample low-level moisture and steep mid-level lapse rates will result in strong to very strong buoyancy to the south of the MCS from the MN/IA border into northern/central IL. Given the lack of a well-defined surface boundary and negligible large-scale ascent, additional thunderstorm development will be associated with outflow from with the MCS, which results in greater-than-average uncertainty for the Day 1 period. Ample moisture and buoyancy downstream of the leading edge of the MCS suggests the greater severe potential this afternoon/evening will likely be associated with redevelopment/reintensification of the MCS. Additionally, even if reintensification does not occur along the leading edge of the MCS this afternoon, most guidance suggests redevelopment does eventually occur this evening along the southern periphery of the MCV circulation as it moves into northern/central WI. Increased severe-wind probabilities (i.e. 15%) were introduced with this outlook to cover both of these potential scenarios. A small 15% hail probability was introduce to cover potential for later evening storms atop the outflow as well. Storms are possible into northern IN and the Lower MI this afternoon and evening as well, but the lower buoyancy should temper the overall coverage and magnitude in these areas. ...SD and Vicinity... A well-defined but rather weak shortwave trough is currently moving through western CO/western WY, and will continue northeastward into eastern WY/western Dakotas by this evening. Similar to yesterday, high-based storms will develop ahead of the approaching shortwave and intensify as they move eastward into a progressively more moist/unstable air mass over west-central SD. Upscale growth into another nocturnal MCS is forecast by most guidance, with the MCS tracking northeastward across western/central SD tonight. Strong to severe gusts are possible with this potential MCS across much of western/central SD. Read more