Severe Storms

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0200 AM CDT Fri Aug 15 2025 Valid 161200Z - 171200Z ...Synopsis... Troughing over the West will gradually intensify Friday as central US ridging also builds and gradually shifts eastward. As western US troughing deepens, southwesterly flow aloft will continue over the Great Basin and Intermountain West. A cold front will move through the Northwest, bringing showers and thunderstorms to parts of OR, WA and northern CA, while dry and breezy conditions will persist over the southern Great Basin. ...Dry Thunderstorms... Across the Northwest and central Rockies, persistent monsoon moisture will be in palace ahead of the upper trough and advancing cold front. Widespread wetting rainfall is expected across much of the Pacific Northwest west of the Cascades. To the east, diurnal heating and more modest moisture should support a relatively dry boundary layer with drier storms. isolated to scattered storms are expected along the cold front from eastern OR into western ID. While some wetting rainfall is possible, the modest moisture and faster storm speed should still support isolated dry thunder potential over the Northeast and central Rockies Friday afternoon into the early evening. ...Southern Great Basin... As the western US trough slowly deepens, southwesterly flow aloft will remain fairly modest over the West. Still, some increase is expected over portions of southern NV and western UT. While not overly strong, afternoon westerly winds near 15 mph appear possible Friday afternoon. With low RH (below 15) locally elevated fire-weather conditions will be possible for a few hours amidst dry fuels. The lack of stronger winds for now precludes elevated Highlights. ..Lyons.. 08/15/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0200 AM CDT Fri Aug 15 2025 Valid 161200Z - 171200Z ...Synopsis... Troughing over the West will gradually intensify Friday as central US ridging also builds and gradually shifts eastward. As western US troughing deepens, southwesterly flow aloft will continue over the Great Basin and Intermountain West. A cold front will move through the Northwest, bringing showers and thunderstorms to parts of OR, WA and northern CA, while dry and breezy conditions will persist over the southern Great Basin. ...Dry Thunderstorms... Across the Northwest and central Rockies, persistent monsoon moisture will be in palace ahead of the upper trough and advancing cold front. Widespread wetting rainfall is expected across much of the Pacific Northwest west of the Cascades. To the east, diurnal heating and more modest moisture should support a relatively dry boundary layer with drier storms. isolated to scattered storms are expected along the cold front from eastern OR into western ID. While some wetting rainfall is possible, the modest moisture and faster storm speed should still support isolated dry thunder potential over the Northeast and central Rockies Friday afternoon into the early evening. ...Southern Great Basin... As the western US trough slowly deepens, southwesterly flow aloft will remain fairly modest over the West. Still, some increase is expected over portions of southern NV and western UT. While not overly strong, afternoon westerly winds near 15 mph appear possible Friday afternoon. With low RH (below 15) locally elevated fire-weather conditions will be possible for a few hours amidst dry fuels. The lack of stronger winds for now precludes elevated Highlights. ..Lyons.. 08/15/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0200 AM CDT Fri Aug 15 2025 Valid 161200Z - 171200Z ...Synopsis... Troughing over the West will gradually intensify Friday as central US ridging also builds and gradually shifts eastward. As western US troughing deepens, southwesterly flow aloft will continue over the Great Basin and Intermountain West. A cold front will move through the Northwest, bringing showers and thunderstorms to parts of OR, WA and northern CA, while dry and breezy conditions will persist over the southern Great Basin. ...Dry Thunderstorms... Across the Northwest and central Rockies, persistent monsoon moisture will be in palace ahead of the upper trough and advancing cold front. Widespread wetting rainfall is expected across much of the Pacific Northwest west of the Cascades. To the east, diurnal heating and more modest moisture should support a relatively dry boundary layer with drier storms. isolated to scattered storms are expected along the cold front from eastern OR into western ID. While some wetting rainfall is possible, the modest moisture and faster storm speed should still support isolated dry thunder potential over the Northeast and central Rockies Friday afternoon into the early evening. ...Southern Great Basin... As the western US trough slowly deepens, southwesterly flow aloft will remain fairly modest over the West. Still, some increase is expected over portions of southern NV and western UT. While not overly strong, afternoon westerly winds near 15 mph appear possible Friday afternoon. With low RH (below 15) locally elevated fire-weather conditions will be possible for a few hours amidst dry fuels. The lack of stronger winds for now precludes elevated Highlights. ..Lyons.. 08/15/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0200 AM CDT Fri Aug 15 2025 Valid 161200Z - 171200Z ...Synopsis... Troughing over the West will gradually intensify Friday as central US ridging also builds and gradually shifts eastward. As western US troughing deepens, southwesterly flow aloft will continue over the Great Basin and Intermountain West. A cold front will move through the Northwest, bringing showers and thunderstorms to parts of OR, WA and northern CA, while dry and breezy conditions will persist over the southern Great Basin. ...Dry Thunderstorms... Across the Northwest and central Rockies, persistent monsoon moisture will be in palace ahead of the upper trough and advancing cold front. Widespread wetting rainfall is expected across much of the Pacific Northwest west of the Cascades. To the east, diurnal heating and more modest moisture should support a relatively dry boundary layer with drier storms. isolated to scattered storms are expected along the cold front from eastern OR into western ID. While some wetting rainfall is possible, the modest moisture and faster storm speed should still support isolated dry thunder potential over the Northeast and central Rockies Friday afternoon into the early evening. ...Southern Great Basin... As the western US trough slowly deepens, southwesterly flow aloft will remain fairly modest over the West. Still, some increase is expected over portions of southern NV and western UT. While not overly strong, afternoon westerly winds near 15 mph appear possible Friday afternoon. With low RH (below 15) locally elevated fire-weather conditions will be possible for a few hours amidst dry fuels. The lack of stronger winds for now precludes elevated Highlights. ..Lyons.. 08/15/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CDT Fri Aug 15 2025 Valid 151200Z - 161200Z ...Synopsis... Broad mid-level ridging over the Central US is forecast to build today, as weak westerly flow passes over it. Weak troughing over the Great Basin will gradually shift eastward bolstering mid-level flow over the region. A weak lee low over the High Plains will support west/southwesterly winds over much of the Great Basin and Intermountain West through this afternoon. 15-20 mph gusts will overlap with very warm and dry conditions (RH below 15) from eastern NV into portions of UT, WY and ID. Several hours of elevated fire weather conditions are probable given very dry and receptive fuels. ...Dry Thunder... Weak height falls from the upper trough over the West will continue to overspread robust monsoon moisture supporting isolated thunderstorms this afternoon. Similar to previous days, a combination of steep mid-level lapse rates and modest mid-level moisture will overlap with dry boundary layer conditions and high cloud bases. This will favor dry storms with limited potential for wetting rainfall. The favorable thermodynamic conditions, coupled with 15-25 knot storm motions over top receptive fuels will continue to support dry lightning potential with these storms over the eastern Great Basin and central Rockies. ..Lyons.. 08/15/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CDT Fri Aug 15 2025 Valid 151200Z - 161200Z ...Synopsis... Broad mid-level ridging over the Central US is forecast to build today, as weak westerly flow passes over it. Weak troughing over the Great Basin will gradually shift eastward bolstering mid-level flow over the region. A weak lee low over the High Plains will support west/southwesterly winds over much of the Great Basin and Intermountain West through this afternoon. 15-20 mph gusts will overlap with very warm and dry conditions (RH below 15) from eastern NV into portions of UT, WY and ID. Several hours of elevated fire weather conditions are probable given very dry and receptive fuels. ...Dry Thunder... Weak height falls from the upper trough over the West will continue to overspread robust monsoon moisture supporting isolated thunderstorms this afternoon. Similar to previous days, a combination of steep mid-level lapse rates and modest mid-level moisture will overlap with dry boundary layer conditions and high cloud bases. This will favor dry storms with limited potential for wetting rainfall. The favorable thermodynamic conditions, coupled with 15-25 knot storm motions over top receptive fuels will continue to support dry lightning potential with these storms over the eastern Great Basin and central Rockies. ..Lyons.. 08/15/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CDT Fri Aug 15 2025 Valid 151200Z - 161200Z ...Synopsis... Broad mid-level ridging over the Central US is forecast to build today, as weak westerly flow passes over it. Weak troughing over the Great Basin will gradually shift eastward bolstering mid-level flow over the region. A weak lee low over the High Plains will support west/southwesterly winds over much of the Great Basin and Intermountain West through this afternoon. 15-20 mph gusts will overlap with very warm and dry conditions (RH below 15) from eastern NV into portions of UT, WY and ID. Several hours of elevated fire weather conditions are probable given very dry and receptive fuels. ...Dry Thunder... Weak height falls from the upper trough over the West will continue to overspread robust monsoon moisture supporting isolated thunderstorms this afternoon. Similar to previous days, a combination of steep mid-level lapse rates and modest mid-level moisture will overlap with dry boundary layer conditions and high cloud bases. This will favor dry storms with limited potential for wetting rainfall. The favorable thermodynamic conditions, coupled with 15-25 knot storm motions over top receptive fuels will continue to support dry lightning potential with these storms over the eastern Great Basin and central Rockies. ..Lyons.. 08/15/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CDT Fri Aug 15 2025 Valid 151200Z - 161200Z ...Synopsis... Broad mid-level ridging over the Central US is forecast to build today, as weak westerly flow passes over it. Weak troughing over the Great Basin will gradually shift eastward bolstering mid-level flow over the region. A weak lee low over the High Plains will support west/southwesterly winds over much of the Great Basin and Intermountain West through this afternoon. 15-20 mph gusts will overlap with very warm and dry conditions (RH below 15) from eastern NV into portions of UT, WY and ID. Several hours of elevated fire weather conditions are probable given very dry and receptive fuels. ...Dry Thunder... Weak height falls from the upper trough over the West will continue to overspread robust monsoon moisture supporting isolated thunderstorms this afternoon. Similar to previous days, a combination of steep mid-level lapse rates and modest mid-level moisture will overlap with dry boundary layer conditions and high cloud bases. This will favor dry storms with limited potential for wetting rainfall. The favorable thermodynamic conditions, coupled with 15-25 knot storm motions over top receptive fuels will continue to support dry lightning potential with these storms over the eastern Great Basin and central Rockies. ..Lyons.. 08/15/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CDT Fri Aug 15 2025 Valid 151200Z - 161200Z ...Synopsis... Broad mid-level ridging over the Central US is forecast to build today, as weak westerly flow passes over it. Weak troughing over the Great Basin will gradually shift eastward bolstering mid-level flow over the region. A weak lee low over the High Plains will support west/southwesterly winds over much of the Great Basin and Intermountain West through this afternoon. 15-20 mph gusts will overlap with very warm and dry conditions (RH below 15) from eastern NV into portions of UT, WY and ID. Several hours of elevated fire weather conditions are probable given very dry and receptive fuels. ...Dry Thunder... Weak height falls from the upper trough over the West will continue to overspread robust monsoon moisture supporting isolated thunderstorms this afternoon. Similar to previous days, a combination of steep mid-level lapse rates and modest mid-level moisture will overlap with dry boundary layer conditions and high cloud bases. This will favor dry storms with limited potential for wetting rainfall. The favorable thermodynamic conditions, coupled with 15-25 knot storm motions over top receptive fuels will continue to support dry lightning potential with these storms over the eastern Great Basin and central Rockies. ..Lyons.. 08/15/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CDT Fri Aug 15 2025 Valid 151200Z - 161200Z ...Synopsis... Broad mid-level ridging over the Central US is forecast to build today, as weak westerly flow passes over it. Weak troughing over the Great Basin will gradually shift eastward bolstering mid-level flow over the region. A weak lee low over the High Plains will support west/southwesterly winds over much of the Great Basin and Intermountain West through this afternoon. 15-20 mph gusts will overlap with very warm and dry conditions (RH below 15) from eastern NV into portions of UT, WY and ID. Several hours of elevated fire weather conditions are probable given very dry and receptive fuels. ...Dry Thunder... Weak height falls from the upper trough over the West will continue to overspread robust monsoon moisture supporting isolated thunderstorms this afternoon. Similar to previous days, a combination of steep mid-level lapse rates and modest mid-level moisture will overlap with dry boundary layer conditions and high cloud bases. This will favor dry storms with limited potential for wetting rainfall. The favorable thermodynamic conditions, coupled with 15-25 knot storm motions over top receptive fuels will continue to support dry lightning potential with these storms over the eastern Great Basin and central Rockies. ..Lyons.. 08/15/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Fri Aug 15 2025 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE NORTHERN HIGH PLAINS EASTWARD TO THE GREAT LAKES... ...SUMMARY... Thunderstorms with a potential for isolated severe gusts and hail will be possible on Saturday from parts of the central and northern Plains eastward to the Great Lakes. ...Central and Northern Plains... At mid-levels, a ridge will move across the northern Plains on Saturday, as southwesterly flow remains from the northern Rockies into the northern High Plains. At the surface, an upslope flow regime will remain in place from the Dakotas into eastern Montana. A surface trough will deepen during the day over the northern High Plains. Although large-scale ascent will remain weak across the region, isolated thunderstorms may develop in the afternoon near the surface trough. Additional isolated storms could develop near and to the north of a front located across northern Nebraska. To the north of the front, a moist and unstable airmass is forecast. Moderate instability will be in place over much of this airmass by afternoon. Although deep-layer shear will remain near or below 35 knots over most of this airmass, low to mid-level lapse rates will be steep. This could be enough for isolated severe gusts and hail with any cell that can develop and persist in the late afternoon and early evening. ...Upper Mississippi Valley/Great Lakes... West-northwesterly mid-level flow will remain in place on Saturday from the upper Mississippi Valley into the Great Lakes, as a mid-level ridge moves across the northern Plains. At the surface, a front is forecast to remain in place from far northern Iowa into southern Wisconsin. From near the boundary southward, surface dewpoints are forecast to be in the lower to mid 70s F. This will contribute to a strongly unstable airmass by afternoon. Although large-scale ascent will remain weak across the region, isolated thunderstorms may develop along pre-existing boundaries or along zones of maximized low-level convergence. NAM forecast soundings near and to the north of the front across the upper Mississippi Valley have 0-6 km shear in the 30 to 40 knot range, with 700-500 mb lapse rates of 7 to 7.5 C/km. This could be enough for isolated rotating storms with potential for hail and severe wind gusts. A potential for severe gusts could extend eastward into parts of the Great Lakes where moderate instability is forecast, but deep-layer shear will be more modest. ..Broyles.. 08/15/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Fri Aug 15 2025 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE NORTHERN HIGH PLAINS EASTWARD TO THE GREAT LAKES... ...SUMMARY... Thunderstorms with a potential for isolated severe gusts and hail will be possible on Saturday from parts of the central and northern Plains eastward to the Great Lakes. ...Central and Northern Plains... At mid-levels, a ridge will move across the northern Plains on Saturday, as southwesterly flow remains from the northern Rockies into the northern High Plains. At the surface, an upslope flow regime will remain in place from the Dakotas into eastern Montana. A surface trough will deepen during the day over the northern High Plains. Although large-scale ascent will remain weak across the region, isolated thunderstorms may develop in the afternoon near the surface trough. Additional isolated storms could develop near and to the north of a front located across northern Nebraska. To the north of the front, a moist and unstable airmass is forecast. Moderate instability will be in place over much of this airmass by afternoon. Although deep-layer shear will remain near or below 35 knots over most of this airmass, low to mid-level lapse rates will be steep. This could be enough for isolated severe gusts and hail with any cell that can develop and persist in the late afternoon and early evening. ...Upper Mississippi Valley/Great Lakes... West-northwesterly mid-level flow will remain in place on Saturday from the upper Mississippi Valley into the Great Lakes, as a mid-level ridge moves across the northern Plains. At the surface, a front is forecast to remain in place from far northern Iowa into southern Wisconsin. From near the boundary southward, surface dewpoints are forecast to be in the lower to mid 70s F. This will contribute to a strongly unstable airmass by afternoon. Although large-scale ascent will remain weak across the region, isolated thunderstorms may develop along pre-existing boundaries or along zones of maximized low-level convergence. NAM forecast soundings near and to the north of the front across the upper Mississippi Valley have 0-6 km shear in the 30 to 40 knot range, with 700-500 mb lapse rates of 7 to 7.5 C/km. This could be enough for isolated rotating storms with potential for hail and severe wind gusts. A potential for severe gusts could extend eastward into parts of the Great Lakes where moderate instability is forecast, but deep-layer shear will be more modest. ..Broyles.. 08/15/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Fri Aug 15 2025 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE NORTHERN HIGH PLAINS EASTWARD TO THE GREAT LAKES... ...SUMMARY... Thunderstorms with a potential for isolated severe gusts and hail will be possible on Saturday from parts of the central and northern Plains eastward to the Great Lakes. ...Central and Northern Plains... At mid-levels, a ridge will move across the northern Plains on Saturday, as southwesterly flow remains from the northern Rockies into the northern High Plains. At the surface, an upslope flow regime will remain in place from the Dakotas into eastern Montana. A surface trough will deepen during the day over the northern High Plains. Although large-scale ascent will remain weak across the region, isolated thunderstorms may develop in the afternoon near the surface trough. Additional isolated storms could develop near and to the north of a front located across northern Nebraska. To the north of the front, a moist and unstable airmass is forecast. Moderate instability will be in place over much of this airmass by afternoon. Although deep-layer shear will remain near or below 35 knots over most of this airmass, low to mid-level lapse rates will be steep. This could be enough for isolated severe gusts and hail with any cell that can develop and persist in the late afternoon and early evening. ...Upper Mississippi Valley/Great Lakes... West-northwesterly mid-level flow will remain in place on Saturday from the upper Mississippi Valley into the Great Lakes, as a mid-level ridge moves across the northern Plains. At the surface, a front is forecast to remain in place from far northern Iowa into southern Wisconsin. From near the boundary southward, surface dewpoints are forecast to be in the lower to mid 70s F. This will contribute to a strongly unstable airmass by afternoon. Although large-scale ascent will remain weak across the region, isolated thunderstorms may develop along pre-existing boundaries or along zones of maximized low-level convergence. NAM forecast soundings near and to the north of the front across the upper Mississippi Valley have 0-6 km shear in the 30 to 40 knot range, with 700-500 mb lapse rates of 7 to 7.5 C/km. This could be enough for isolated rotating storms with potential for hail and severe wind gusts. A potential for severe gusts could extend eastward into parts of the Great Lakes where moderate instability is forecast, but deep-layer shear will be more modest. ..Broyles.. 08/15/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Fri Aug 15 2025 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE NORTHERN HIGH PLAINS EASTWARD TO THE GREAT LAKES... ...SUMMARY... Thunderstorms with a potential for isolated severe gusts and hail will be possible on Saturday from parts of the central and northern Plains eastward to the Great Lakes. ...Central and Northern Plains... At mid-levels, a ridge will move across the northern Plains on Saturday, as southwesterly flow remains from the northern Rockies into the northern High Plains. At the surface, an upslope flow regime will remain in place from the Dakotas into eastern Montana. A surface trough will deepen during the day over the northern High Plains. Although large-scale ascent will remain weak across the region, isolated thunderstorms may develop in the afternoon near the surface trough. Additional isolated storms could develop near and to the north of a front located across northern Nebraska. To the north of the front, a moist and unstable airmass is forecast. Moderate instability will be in place over much of this airmass by afternoon. Although deep-layer shear will remain near or below 35 knots over most of this airmass, low to mid-level lapse rates will be steep. This could be enough for isolated severe gusts and hail with any cell that can develop and persist in the late afternoon and early evening. ...Upper Mississippi Valley/Great Lakes... West-northwesterly mid-level flow will remain in place on Saturday from the upper Mississippi Valley into the Great Lakes, as a mid-level ridge moves across the northern Plains. At the surface, a front is forecast to remain in place from far northern Iowa into southern Wisconsin. From near the boundary southward, surface dewpoints are forecast to be in the lower to mid 70s F. This will contribute to a strongly unstable airmass by afternoon. Although large-scale ascent will remain weak across the region, isolated thunderstorms may develop along pre-existing boundaries or along zones of maximized low-level convergence. NAM forecast soundings near and to the north of the front across the upper Mississippi Valley have 0-6 km shear in the 30 to 40 knot range, with 700-500 mb lapse rates of 7 to 7.5 C/km. This could be enough for isolated rotating storms with potential for hail and severe wind gusts. A potential for severe gusts could extend eastward into parts of the Great Lakes where moderate instability is forecast, but deep-layer shear will be more modest. ..Broyles.. 08/15/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Fri Aug 15 2025 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE NORTHERN HIGH PLAINS EASTWARD TO THE GREAT LAKES... ...SUMMARY... Thunderstorms with a potential for isolated severe gusts and hail will be possible on Saturday from parts of the central and northern Plains eastward to the Great Lakes. ...Central and Northern Plains... At mid-levels, a ridge will move across the northern Plains on Saturday, as southwesterly flow remains from the northern Rockies into the northern High Plains. At the surface, an upslope flow regime will remain in place from the Dakotas into eastern Montana. A surface trough will deepen during the day over the northern High Plains. Although large-scale ascent will remain weak across the region, isolated thunderstorms may develop in the afternoon near the surface trough. Additional isolated storms could develop near and to the north of a front located across northern Nebraska. To the north of the front, a moist and unstable airmass is forecast. Moderate instability will be in place over much of this airmass by afternoon. Although deep-layer shear will remain near or below 35 knots over most of this airmass, low to mid-level lapse rates will be steep. This could be enough for isolated severe gusts and hail with any cell that can develop and persist in the late afternoon and early evening. ...Upper Mississippi Valley/Great Lakes... West-northwesterly mid-level flow will remain in place on Saturday from the upper Mississippi Valley into the Great Lakes, as a mid-level ridge moves across the northern Plains. At the surface, a front is forecast to remain in place from far northern Iowa into southern Wisconsin. From near the boundary southward, surface dewpoints are forecast to be in the lower to mid 70s F. This will contribute to a strongly unstable airmass by afternoon. Although large-scale ascent will remain weak across the region, isolated thunderstorms may develop along pre-existing boundaries or along zones of maximized low-level convergence. NAM forecast soundings near and to the north of the front across the upper Mississippi Valley have 0-6 km shear in the 30 to 40 knot range, with 700-500 mb lapse rates of 7 to 7.5 C/km. This could be enough for isolated rotating storms with potential for hail and severe wind gusts. A potential for severe gusts could extend eastward into parts of the Great Lakes where moderate instability is forecast, but deep-layer shear will be more modest. ..Broyles.. 08/15/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Fri Aug 15 2025 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE NORTHERN HIGH PLAINS EASTWARD TO THE GREAT LAKES... ...SUMMARY... Thunderstorms with a potential for isolated severe gusts and hail will be possible on Saturday from parts of the central and northern Plains eastward to the Great Lakes. ...Central and Northern Plains... At mid-levels, a ridge will move across the northern Plains on Saturday, as southwesterly flow remains from the northern Rockies into the northern High Plains. At the surface, an upslope flow regime will remain in place from the Dakotas into eastern Montana. A surface trough will deepen during the day over the northern High Plains. Although large-scale ascent will remain weak across the region, isolated thunderstorms may develop in the afternoon near the surface trough. Additional isolated storms could develop near and to the north of a front located across northern Nebraska. To the north of the front, a moist and unstable airmass is forecast. Moderate instability will be in place over much of this airmass by afternoon. Although deep-layer shear will remain near or below 35 knots over most of this airmass, low to mid-level lapse rates will be steep. This could be enough for isolated severe gusts and hail with any cell that can develop and persist in the late afternoon and early evening. ...Upper Mississippi Valley/Great Lakes... West-northwesterly mid-level flow will remain in place on Saturday from the upper Mississippi Valley into the Great Lakes, as a mid-level ridge moves across the northern Plains. At the surface, a front is forecast to remain in place from far northern Iowa into southern Wisconsin. From near the boundary southward, surface dewpoints are forecast to be in the lower to mid 70s F. This will contribute to a strongly unstable airmass by afternoon. Although large-scale ascent will remain weak across the region, isolated thunderstorms may develop along pre-existing boundaries or along zones of maximized low-level convergence. NAM forecast soundings near and to the north of the front across the upper Mississippi Valley have 0-6 km shear in the 30 to 40 knot range, with 700-500 mb lapse rates of 7 to 7.5 C/km. This could be enough for isolated rotating storms with potential for hail and severe wind gusts. A potential for severe gusts could extend eastward into parts of the Great Lakes where moderate instability is forecast, but deep-layer shear will be more modest. ..Broyles.. 08/15/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1232 AM CDT Fri Aug 15 2025 Valid 151200Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY... ...SUMMARY... Scattered severe storms are likely over parts of the northern Plains and Upper Mississippi Valley. ...Northern Plains/Upper MS Valley... Broad anticyclonic flow is forecast to continue across the central/southern Plains during the day1 period. Stronger 500mb flow will extend around the periphery of this feature, extending from the northern Rockies-northern Plains-upper Great Lakes. While a few disturbances will eject across the northern Rockies toward the upper MS Valley, latest model guidance suggests heights will actually rise much of the period. One such feature currently extends from eastern WY into northeast CO. Scattered thunderstorms are noted immediately downstream from the Black Hills into western NE. This disturbance should advance into central SD by the start of the period, then into MN by early afternoon. While a few strong storms may be ongoing at the start of the period, renewed development is expected during the afternoon across the upper MS Valley. LLJ is forecast to increase a bit into southwest MN ahead of the short wave, and this should encourage robust convection along a front that will be draped from southwest MN-northern WI. Strong buoyancy will be noted south of the front across much of this region and MLCAPE could exceed 3000 J/kg from MN/IA into SD/NE. While the short wave should encourage organized convection, boundary-layer heating will prove instrumental in thunderstorm development. Forecast soundings suggest CINH weakens considerably by 19-21z and convection should expand in areal coverage as convective temperatures are breached. Wind/hail are the primary risks, though a brief tornado can not be ruled out with any supercell structures. Farther west, convective temperatures will be breached across eastern WY by 22z. Scattered storms will once again develop over the higher terrain/Plains then spread downstream into western SD/northwestern NE during the evening. Some consideration was given to a SLGT risk for this activity but the short-wave trough that should affect this region will eject across northern AZ into southwest WY around 16/00z. Timing of this feature suggests stronger support will not affect this region until well after sunset. ..Darrow/Lyons.. 08/15/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1232 AM CDT Fri Aug 15 2025 Valid 151200Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY... ...SUMMARY... Scattered severe storms are likely over parts of the northern Plains and Upper Mississippi Valley. ...Northern Plains/Upper MS Valley... Broad anticyclonic flow is forecast to continue across the central/southern Plains during the day1 period. Stronger 500mb flow will extend around the periphery of this feature, extending from the northern Rockies-northern Plains-upper Great Lakes. While a few disturbances will eject across the northern Rockies toward the upper MS Valley, latest model guidance suggests heights will actually rise much of the period. One such feature currently extends from eastern WY into northeast CO. Scattered thunderstorms are noted immediately downstream from the Black Hills into western NE. This disturbance should advance into central SD by the start of the period, then into MN by early afternoon. While a few strong storms may be ongoing at the start of the period, renewed development is expected during the afternoon across the upper MS Valley. LLJ is forecast to increase a bit into southwest MN ahead of the short wave, and this should encourage robust convection along a front that will be draped from southwest MN-northern WI. Strong buoyancy will be noted south of the front across much of this region and MLCAPE could exceed 3000 J/kg from MN/IA into SD/NE. While the short wave should encourage organized convection, boundary-layer heating will prove instrumental in thunderstorm development. Forecast soundings suggest CINH weakens considerably by 19-21z and convection should expand in areal coverage as convective temperatures are breached. Wind/hail are the primary risks, though a brief tornado can not be ruled out with any supercell structures. Farther west, convective temperatures will be breached across eastern WY by 22z. Scattered storms will once again develop over the higher terrain/Plains then spread downstream into western SD/northwestern NE during the evening. Some consideration was given to a SLGT risk for this activity but the short-wave trough that should affect this region will eject across northern AZ into southwest WY around 16/00z. Timing of this feature suggests stronger support will not affect this region until well after sunset. ..Darrow/Lyons.. 08/15/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1232 AM CDT Fri Aug 15 2025 Valid 151200Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY... ...SUMMARY... Scattered severe storms are likely over parts of the northern Plains and Upper Mississippi Valley. ...Northern Plains/Upper MS Valley... Broad anticyclonic flow is forecast to continue across the central/southern Plains during the day1 period. Stronger 500mb flow will extend around the periphery of this feature, extending from the northern Rockies-northern Plains-upper Great Lakes. While a few disturbances will eject across the northern Rockies toward the upper MS Valley, latest model guidance suggests heights will actually rise much of the period. One such feature currently extends from eastern WY into northeast CO. Scattered thunderstorms are noted immediately downstream from the Black Hills into western NE. This disturbance should advance into central SD by the start of the period, then into MN by early afternoon. While a few strong storms may be ongoing at the start of the period, renewed development is expected during the afternoon across the upper MS Valley. LLJ is forecast to increase a bit into southwest MN ahead of the short wave, and this should encourage robust convection along a front that will be draped from southwest MN-northern WI. Strong buoyancy will be noted south of the front across much of this region and MLCAPE could exceed 3000 J/kg from MN/IA into SD/NE. While the short wave should encourage organized convection, boundary-layer heating will prove instrumental in thunderstorm development. Forecast soundings suggest CINH weakens considerably by 19-21z and convection should expand in areal coverage as convective temperatures are breached. Wind/hail are the primary risks, though a brief tornado can not be ruled out with any supercell structures. Farther west, convective temperatures will be breached across eastern WY by 22z. Scattered storms will once again develop over the higher terrain/Plains then spread downstream into western SD/northwestern NE during the evening. Some consideration was given to a SLGT risk for this activity but the short-wave trough that should affect this region will eject across northern AZ into southwest WY around 16/00z. Timing of this feature suggests stronger support will not affect this region until well after sunset. ..Darrow/Lyons.. 08/15/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1232 AM CDT Fri Aug 15 2025 Valid 151200Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY... ...SUMMARY... Scattered severe storms are likely over parts of the northern Plains and Upper Mississippi Valley. ...Northern Plains/Upper MS Valley... Broad anticyclonic flow is forecast to continue across the central/southern Plains during the day1 period. Stronger 500mb flow will extend around the periphery of this feature, extending from the northern Rockies-northern Plains-upper Great Lakes. While a few disturbances will eject across the northern Rockies toward the upper MS Valley, latest model guidance suggests heights will actually rise much of the period. One such feature currently extends from eastern WY into northeast CO. Scattered thunderstorms are noted immediately downstream from the Black Hills into western NE. This disturbance should advance into central SD by the start of the period, then into MN by early afternoon. While a few strong storms may be ongoing at the start of the period, renewed development is expected during the afternoon across the upper MS Valley. LLJ is forecast to increase a bit into southwest MN ahead of the short wave, and this should encourage robust convection along a front that will be draped from southwest MN-northern WI. Strong buoyancy will be noted south of the front across much of this region and MLCAPE could exceed 3000 J/kg from MN/IA into SD/NE. While the short wave should encourage organized convection, boundary-layer heating will prove instrumental in thunderstorm development. Forecast soundings suggest CINH weakens considerably by 19-21z and convection should expand in areal coverage as convective temperatures are breached. Wind/hail are the primary risks, though a brief tornado can not be ruled out with any supercell structures. Farther west, convective temperatures will be breached across eastern WY by 22z. Scattered storms will once again develop over the higher terrain/Plains then spread downstream into western SD/northwestern NE during the evening. Some consideration was given to a SLGT risk for this activity but the short-wave trough that should affect this region will eject across northern AZ into southwest WY around 16/00z. Timing of this feature suggests stronger support will not affect this region until well after sunset. ..Darrow/Lyons.. 08/15/2025 Read more