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SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0751 AM CDT Fri Sep 27 2024 Valid 271300Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERNMOST SOUTH CAROLINA OVER PORTIONS OF SOUTHERN/EASTERN NORTH CAROLINA... ...SUMMARY... Tornadoes will be most likely through midday and remain possible into afternoon across parts of the Carolinas and Virginia. ...Synopsis... In mid/upper levels, a zonal to west-southwesterly belt of flow will persist from the northwestern CONUS and western Canada into central Canada, well-removed from a cut-off, cold-core low now evident in moisture-channel imagery over northern MS. This low is expected to pivot slowly northeastward into middle TN by 00Z, then wobble erratically over that area and/or south-central KY through the night as it absorbs the remnant vorticity max from what is now Tropical Storm Helene. ...SC/NC/VA... The path of center of Tropical Storm Helene finally has turned northward. See SPC Tornado watch 688 and associated mesoscale discussions for near-term coverage of the tornado threat over the region. Refer to NHC advisories for the latest track/intensity guidance on Helene. The NHC forecast shows that the center should bend northwestward across southwestern NC, eastern TN and into southern KY through tonight, weakening greatly and becoming more closely conjoined with the mid/upper cyclone. For several more hours, into at least midday, a broad area of strong low-level flow above the surface, and related large low-level shear/hodographs, should extend well east and northeast of center across the outlook area, superimposed over: 1. Relatively maximized low-level convergence, in an arc initially located over eastern SC into southern NC, preceded by well-backed surface winds, and forecast to shift northward to northeastward today; 2. A richly moist, high-theta-e and weak-MLCINH boundary layer advecting inland from the Atlantic and characterized by surface dewpoints commonly in the 70s F. These conditions will yield a favorable environment for tornadoes from any supercells that can cross it, whether within or ahead of the main spiral/convergence band. The most probable area for several supercells to interact with this favorable airmass is over the 10%/"enhanced" tornado-risk area, with potential decreasing westward and northward from there due to weaker instability. Although the supportive low-level airmass will continue to shift northeastward over eastern NC and south-central/southeastern VA this afternoon, tornado potential will diminish with time from midafternoon into early evening. This will occur as convection decreases in coverage and intensity across the area due to a combination of weakening lift and shear, as the remnants of Helene decay rapidly and back well westward away from the area. This process will decouple the remaining stronger low-level flow and isallobaric forcing away from the most-favorable boundary layer near the coast, where hodographs should shrink by the hour this afternoon into evening. ..Edwards/Broyles.. 09/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0751 AM CDT Fri Sep 27 2024 Valid 271300Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERNMOST SOUTH CAROLINA OVER PORTIONS OF SOUTHERN/EASTERN NORTH CAROLINA... ...SUMMARY... Tornadoes will be most likely through midday and remain possible into afternoon across parts of the Carolinas and Virginia. ...Synopsis... In mid/upper levels, a zonal to west-southwesterly belt of flow will persist from the northwestern CONUS and western Canada into central Canada, well-removed from a cut-off, cold-core low now evident in moisture-channel imagery over northern MS. This low is expected to pivot slowly northeastward into middle TN by 00Z, then wobble erratically over that area and/or south-central KY through the night as it absorbs the remnant vorticity max from what is now Tropical Storm Helene. ...SC/NC/VA... The path of center of Tropical Storm Helene finally has turned northward. See SPC Tornado watch 688 and associated mesoscale discussions for near-term coverage of the tornado threat over the region. Refer to NHC advisories for the latest track/intensity guidance on Helene. The NHC forecast shows that the center should bend northwestward across southwestern NC, eastern TN and into southern KY through tonight, weakening greatly and becoming more closely conjoined with the mid/upper cyclone. For several more hours, into at least midday, a broad area of strong low-level flow above the surface, and related large low-level shear/hodographs, should extend well east and northeast of center across the outlook area, superimposed over: 1. Relatively maximized low-level convergence, in an arc initially located over eastern SC into southern NC, preceded by well-backed surface winds, and forecast to shift northward to northeastward today; 2. A richly moist, high-theta-e and weak-MLCINH boundary layer advecting inland from the Atlantic and characterized by surface dewpoints commonly in the 70s F. These conditions will yield a favorable environment for tornadoes from any supercells that can cross it, whether within or ahead of the main spiral/convergence band. The most probable area for several supercells to interact with this favorable airmass is over the 10%/"enhanced" tornado-risk area, with potential decreasing westward and northward from there due to weaker instability. Although the supportive low-level airmass will continue to shift northeastward over eastern NC and south-central/southeastern VA this afternoon, tornado potential will diminish with time from midafternoon into early evening. This will occur as convection decreases in coverage and intensity across the area due to a combination of weakening lift and shear, as the remnants of Helene decay rapidly and back well westward away from the area. This process will decouple the remaining stronger low-level flow and isallobaric forcing away from the most-favorable boundary layer near the coast, where hodographs should shrink by the hour this afternoon into evening. ..Edwards/Broyles.. 09/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0751 AM CDT Fri Sep 27 2024 Valid 271300Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERNMOST SOUTH CAROLINA OVER PORTIONS OF SOUTHERN/EASTERN NORTH CAROLINA... ...SUMMARY... Tornadoes will be most likely through midday and remain possible into afternoon across parts of the Carolinas and Virginia. ...Synopsis... In mid/upper levels, a zonal to west-southwesterly belt of flow will persist from the northwestern CONUS and western Canada into central Canada, well-removed from a cut-off, cold-core low now evident in moisture-channel imagery over northern MS. This low is expected to pivot slowly northeastward into middle TN by 00Z, then wobble erratically over that area and/or south-central KY through the night as it absorbs the remnant vorticity max from what is now Tropical Storm Helene. ...SC/NC/VA... The path of center of Tropical Storm Helene finally has turned northward. See SPC Tornado watch 688 and associated mesoscale discussions for near-term coverage of the tornado threat over the region. Refer to NHC advisories for the latest track/intensity guidance on Helene. The NHC forecast shows that the center should bend northwestward across southwestern NC, eastern TN and into southern KY through tonight, weakening greatly and becoming more closely conjoined with the mid/upper cyclone. For several more hours, into at least midday, a broad area of strong low-level flow above the surface, and related large low-level shear/hodographs, should extend well east and northeast of center across the outlook area, superimposed over: 1. Relatively maximized low-level convergence, in an arc initially located over eastern SC into southern NC, preceded by well-backed surface winds, and forecast to shift northward to northeastward today; 2. A richly moist, high-theta-e and weak-MLCINH boundary layer advecting inland from the Atlantic and characterized by surface dewpoints commonly in the 70s F. These conditions will yield a favorable environment for tornadoes from any supercells that can cross it, whether within or ahead of the main spiral/convergence band. The most probable area for several supercells to interact with this favorable airmass is over the 10%/"enhanced" tornado-risk area, with potential decreasing westward and northward from there due to weaker instability. Although the supportive low-level airmass will continue to shift northeastward over eastern NC and south-central/southeastern VA this afternoon, tornado potential will diminish with time from midafternoon into early evening. This will occur as convection decreases in coverage and intensity across the area due to a combination of weakening lift and shear, as the remnants of Helene decay rapidly and back well westward away from the area. This process will decouple the remaining stronger low-level flow and isallobaric forcing away from the most-favorable boundary layer near the coast, where hodographs should shrink by the hour this afternoon into evening. ..Edwards/Broyles.. 09/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0751 AM CDT Fri Sep 27 2024 Valid 271300Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERNMOST SOUTH CAROLINA OVER PORTIONS OF SOUTHERN/EASTERN NORTH CAROLINA... ...SUMMARY... Tornadoes will be most likely through midday and remain possible into afternoon across parts of the Carolinas and Virginia. ...Synopsis... In mid/upper levels, a zonal to west-southwesterly belt of flow will persist from the northwestern CONUS and western Canada into central Canada, well-removed from a cut-off, cold-core low now evident in moisture-channel imagery over northern MS. This low is expected to pivot slowly northeastward into middle TN by 00Z, then wobble erratically over that area and/or south-central KY through the night as it absorbs the remnant vorticity max from what is now Tropical Storm Helene. ...SC/NC/VA... The path of center of Tropical Storm Helene finally has turned northward. See SPC Tornado watch 688 and associated mesoscale discussions for near-term coverage of the tornado threat over the region. Refer to NHC advisories for the latest track/intensity guidance on Helene. The NHC forecast shows that the center should bend northwestward across southwestern NC, eastern TN and into southern KY through tonight, weakening greatly and becoming more closely conjoined with the mid/upper cyclone. For several more hours, into at least midday, a broad area of strong low-level flow above the surface, and related large low-level shear/hodographs, should extend well east and northeast of center across the outlook area, superimposed over: 1. Relatively maximized low-level convergence, in an arc initially located over eastern SC into southern NC, preceded by well-backed surface winds, and forecast to shift northward to northeastward today; 2. A richly moist, high-theta-e and weak-MLCINH boundary layer advecting inland from the Atlantic and characterized by surface dewpoints commonly in the 70s F. These conditions will yield a favorable environment for tornadoes from any supercells that can cross it, whether within or ahead of the main spiral/convergence band. The most probable area for several supercells to interact with this favorable airmass is over the 10%/"enhanced" tornado-risk area, with potential decreasing westward and northward from there due to weaker instability. Although the supportive low-level airmass will continue to shift northeastward over eastern NC and south-central/southeastern VA this afternoon, tornado potential will diminish with time from midafternoon into early evening. This will occur as convection decreases in coverage and intensity across the area due to a combination of weakening lift and shear, as the remnants of Helene decay rapidly and back well westward away from the area. This process will decouple the remaining stronger low-level flow and isallobaric forcing away from the most-favorable boundary layer near the coast, where hodographs should shrink by the hour this afternoon into evening. ..Edwards/Broyles.. 09/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0751 AM CDT Fri Sep 27 2024 Valid 271300Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERNMOST SOUTH CAROLINA OVER PORTIONS OF SOUTHERN/EASTERN NORTH CAROLINA... ...SUMMARY... Tornadoes will be most likely through midday and remain possible into afternoon across parts of the Carolinas and Virginia. ...Synopsis... In mid/upper levels, a zonal to west-southwesterly belt of flow will persist from the northwestern CONUS and western Canada into central Canada, well-removed from a cut-off, cold-core low now evident in moisture-channel imagery over northern MS. This low is expected to pivot slowly northeastward into middle TN by 00Z, then wobble erratically over that area and/or south-central KY through the night as it absorbs the remnant vorticity max from what is now Tropical Storm Helene. ...SC/NC/VA... The path of center of Tropical Storm Helene finally has turned northward. See SPC Tornado watch 688 and associated mesoscale discussions for near-term coverage of the tornado threat over the region. Refer to NHC advisories for the latest track/intensity guidance on Helene. The NHC forecast shows that the center should bend northwestward across southwestern NC, eastern TN and into southern KY through tonight, weakening greatly and becoming more closely conjoined with the mid/upper cyclone. For several more hours, into at least midday, a broad area of strong low-level flow above the surface, and related large low-level shear/hodographs, should extend well east and northeast of center across the outlook area, superimposed over: 1. Relatively maximized low-level convergence, in an arc initially located over eastern SC into southern NC, preceded by well-backed surface winds, and forecast to shift northward to northeastward today; 2. A richly moist, high-theta-e and weak-MLCINH boundary layer advecting inland from the Atlantic and characterized by surface dewpoints commonly in the 70s F. These conditions will yield a favorable environment for tornadoes from any supercells that can cross it, whether within or ahead of the main spiral/convergence band. The most probable area for several supercells to interact with this favorable airmass is over the 10%/"enhanced" tornado-risk area, with potential decreasing westward and northward from there due to weaker instability. Although the supportive low-level airmass will continue to shift northeastward over eastern NC and south-central/southeastern VA this afternoon, tornado potential will diminish with time from midafternoon into early evening. This will occur as convection decreases in coverage and intensity across the area due to a combination of weakening lift and shear, as the remnants of Helene decay rapidly and back well westward away from the area. This process will decouple the remaining stronger low-level flow and isallobaric forcing away from the most-favorable boundary layer near the coast, where hodographs should shrink by the hour this afternoon into evening. ..Edwards/Broyles.. 09/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0751 AM CDT Fri Sep 27 2024 Valid 271300Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERNMOST SOUTH CAROLINA OVER PORTIONS OF SOUTHERN/EASTERN NORTH CAROLINA... ...SUMMARY... Tornadoes will be most likely through midday and remain possible into afternoon across parts of the Carolinas and Virginia. ...Synopsis... In mid/upper levels, a zonal to west-southwesterly belt of flow will persist from the northwestern CONUS and western Canada into central Canada, well-removed from a cut-off, cold-core low now evident in moisture-channel imagery over northern MS. This low is expected to pivot slowly northeastward into middle TN by 00Z, then wobble erratically over that area and/or south-central KY through the night as it absorbs the remnant vorticity max from what is now Tropical Storm Helene. ...SC/NC/VA... The path of center of Tropical Storm Helene finally has turned northward. See SPC Tornado watch 688 and associated mesoscale discussions for near-term coverage of the tornado threat over the region. Refer to NHC advisories for the latest track/intensity guidance on Helene. The NHC forecast shows that the center should bend northwestward across southwestern NC, eastern TN and into southern KY through tonight, weakening greatly and becoming more closely conjoined with the mid/upper cyclone. For several more hours, into at least midday, a broad area of strong low-level flow above the surface, and related large low-level shear/hodographs, should extend well east and northeast of center across the outlook area, superimposed over: 1. Relatively maximized low-level convergence, in an arc initially located over eastern SC into southern NC, preceded by well-backed surface winds, and forecast to shift northward to northeastward today; 2. A richly moist, high-theta-e and weak-MLCINH boundary layer advecting inland from the Atlantic and characterized by surface dewpoints commonly in the 70s F. These conditions will yield a favorable environment for tornadoes from any supercells that can cross it, whether within or ahead of the main spiral/convergence band. The most probable area for several supercells to interact with this favorable airmass is over the 10%/"enhanced" tornado-risk area, with potential decreasing westward and northward from there due to weaker instability. Although the supportive low-level airmass will continue to shift northeastward over eastern NC and south-central/southeastern VA this afternoon, tornado potential will diminish with time from midafternoon into early evening. This will occur as convection decreases in coverage and intensity across the area due to a combination of weakening lift and shear, as the remnants of Helene decay rapidly and back well westward away from the area. This process will decouple the remaining stronger low-level flow and isallobaric forcing away from the most-favorable boundary layer near the coast, where hodographs should shrink by the hour this afternoon into evening. ..Edwards/Broyles.. 09/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0751 AM CDT Fri Sep 27 2024 Valid 271300Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERNMOST SOUTH CAROLINA OVER PORTIONS OF SOUTHERN/EASTERN NORTH CAROLINA... ...SUMMARY... Tornadoes will be most likely through midday and remain possible into afternoon across parts of the Carolinas and Virginia. ...Synopsis... In mid/upper levels, a zonal to west-southwesterly belt of flow will persist from the northwestern CONUS and western Canada into central Canada, well-removed from a cut-off, cold-core low now evident in moisture-channel imagery over northern MS. This low is expected to pivot slowly northeastward into middle TN by 00Z, then wobble erratically over that area and/or south-central KY through the night as it absorbs the remnant vorticity max from what is now Tropical Storm Helene. ...SC/NC/VA... The path of center of Tropical Storm Helene finally has turned northward. See SPC Tornado watch 688 and associated mesoscale discussions for near-term coverage of the tornado threat over the region. Refer to NHC advisories for the latest track/intensity guidance on Helene. The NHC forecast shows that the center should bend northwestward across southwestern NC, eastern TN and into southern KY through tonight, weakening greatly and becoming more closely conjoined with the mid/upper cyclone. For several more hours, into at least midday, a broad area of strong low-level flow above the surface, and related large low-level shear/hodographs, should extend well east and northeast of center across the outlook area, superimposed over: 1. Relatively maximized low-level convergence, in an arc initially located over eastern SC into southern NC, preceded by well-backed surface winds, and forecast to shift northward to northeastward today; 2. A richly moist, high-theta-e and weak-MLCINH boundary layer advecting inland from the Atlantic and characterized by surface dewpoints commonly in the 70s F. These conditions will yield a favorable environment for tornadoes from any supercells that can cross it, whether within or ahead of the main spiral/convergence band. The most probable area for several supercells to interact with this favorable airmass is over the 10%/"enhanced" tornado-risk area, with potential decreasing westward and northward from there due to weaker instability. Although the supportive low-level airmass will continue to shift northeastward over eastern NC and south-central/southeastern VA this afternoon, tornado potential will diminish with time from midafternoon into early evening. This will occur as convection decreases in coverage and intensity across the area due to a combination of weakening lift and shear, as the remnants of Helene decay rapidly and back well westward away from the area. This process will decouple the remaining stronger low-level flow and isallobaric forcing away from the most-favorable boundary layer near the coast, where hodographs should shrink by the hour this afternoon into evening. ..Edwards/Broyles.. 09/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0751 AM CDT Fri Sep 27 2024 Valid 271300Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERNMOST SOUTH CAROLINA OVER PORTIONS OF SOUTHERN/EASTERN NORTH CAROLINA... ...SUMMARY... Tornadoes will be most likely through midday and remain possible into afternoon across parts of the Carolinas and Virginia. ...Synopsis... In mid/upper levels, a zonal to west-southwesterly belt of flow will persist from the northwestern CONUS and western Canada into central Canada, well-removed from a cut-off, cold-core low now evident in moisture-channel imagery over northern MS. This low is expected to pivot slowly northeastward into middle TN by 00Z, then wobble erratically over that area and/or south-central KY through the night as it absorbs the remnant vorticity max from what is now Tropical Storm Helene. ...SC/NC/VA... The path of center of Tropical Storm Helene finally has turned northward. See SPC Tornado watch 688 and associated mesoscale discussions for near-term coverage of the tornado threat over the region. Refer to NHC advisories for the latest track/intensity guidance on Helene. The NHC forecast shows that the center should bend northwestward across southwestern NC, eastern TN and into southern KY through tonight, weakening greatly and becoming more closely conjoined with the mid/upper cyclone. For several more hours, into at least midday, a broad area of strong low-level flow above the surface, and related large low-level shear/hodographs, should extend well east and northeast of center across the outlook area, superimposed over: 1. Relatively maximized low-level convergence, in an arc initially located over eastern SC into southern NC, preceded by well-backed surface winds, and forecast to shift northward to northeastward today; 2. A richly moist, high-theta-e and weak-MLCINH boundary layer advecting inland from the Atlantic and characterized by surface dewpoints commonly in the 70s F. These conditions will yield a favorable environment for tornadoes from any supercells that can cross it, whether within or ahead of the main spiral/convergence band. The most probable area for several supercells to interact with this favorable airmass is over the 10%/"enhanced" tornado-risk area, with potential decreasing westward and northward from there due to weaker instability. Although the supportive low-level airmass will continue to shift northeastward over eastern NC and south-central/southeastern VA this afternoon, tornado potential will diminish with time from midafternoon into early evening. This will occur as convection decreases in coverage and intensity across the area due to a combination of weakening lift and shear, as the remnants of Helene decay rapidly and back well westward away from the area. This process will decouple the remaining stronger low-level flow and isallobaric forcing away from the most-favorable boundary layer near the coast, where hodographs should shrink by the hour this afternoon into evening. ..Edwards/Broyles.. 09/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0751 AM CDT Fri Sep 27 2024 Valid 271300Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERNMOST SOUTH CAROLINA OVER PORTIONS OF SOUTHERN/EASTERN NORTH CAROLINA... ...SUMMARY... Tornadoes will be most likely through midday and remain possible into afternoon across parts of the Carolinas and Virginia. ...Synopsis... In mid/upper levels, a zonal to west-southwesterly belt of flow will persist from the northwestern CONUS and western Canada into central Canada, well-removed from a cut-off, cold-core low now evident in moisture-channel imagery over northern MS. This low is expected to pivot slowly northeastward into middle TN by 00Z, then wobble erratically over that area and/or south-central KY through the night as it absorbs the remnant vorticity max from what is now Tropical Storm Helene. ...SC/NC/VA... The path of center of Tropical Storm Helene finally has turned northward. See SPC Tornado watch 688 and associated mesoscale discussions for near-term coverage of the tornado threat over the region. Refer to NHC advisories for the latest track/intensity guidance on Helene. The NHC forecast shows that the center should bend northwestward across southwestern NC, eastern TN and into southern KY through tonight, weakening greatly and becoming more closely conjoined with the mid/upper cyclone. For several more hours, into at least midday, a broad area of strong low-level flow above the surface, and related large low-level shear/hodographs, should extend well east and northeast of center across the outlook area, superimposed over: 1. Relatively maximized low-level convergence, in an arc initially located over eastern SC into southern NC, preceded by well-backed surface winds, and forecast to shift northward to northeastward today; 2. A richly moist, high-theta-e and weak-MLCINH boundary layer advecting inland from the Atlantic and characterized by surface dewpoints commonly in the 70s F. These conditions will yield a favorable environment for tornadoes from any supercells that can cross it, whether within or ahead of the main spiral/convergence band. The most probable area for several supercells to interact with this favorable airmass is over the 10%/"enhanced" tornado-risk area, with potential decreasing westward and northward from there due to weaker instability. Although the supportive low-level airmass will continue to shift northeastward over eastern NC and south-central/southeastern VA this afternoon, tornado potential will diminish with time from midafternoon into early evening. This will occur as convection decreases in coverage and intensity across the area due to a combination of weakening lift and shear, as the remnants of Helene decay rapidly and back well westward away from the area. This process will decouple the remaining stronger low-level flow and isallobaric forcing away from the most-favorable boundary layer near the coast, where hodographs should shrink by the hour this afternoon into evening. ..Edwards/Broyles.. 09/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0751 AM CDT Fri Sep 27 2024 Valid 271300Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERNMOST SOUTH CAROLINA OVER PORTIONS OF SOUTHERN/EASTERN NORTH CAROLINA... ...SUMMARY... Tornadoes will be most likely through midday and remain possible into afternoon across parts of the Carolinas and Virginia. ...Synopsis... In mid/upper levels, a zonal to west-southwesterly belt of flow will persist from the northwestern CONUS and western Canada into central Canada, well-removed from a cut-off, cold-core low now evident in moisture-channel imagery over northern MS. This low is expected to pivot slowly northeastward into middle TN by 00Z, then wobble erratically over that area and/or south-central KY through the night as it absorbs the remnant vorticity max from what is now Tropical Storm Helene. ...SC/NC/VA... The path of center of Tropical Storm Helene finally has turned northward. See SPC Tornado watch 688 and associated mesoscale discussions for near-term coverage of the tornado threat over the region. Refer to NHC advisories for the latest track/intensity guidance on Helene. The NHC forecast shows that the center should bend northwestward across southwestern NC, eastern TN and into southern KY through tonight, weakening greatly and becoming more closely conjoined with the mid/upper cyclone. For several more hours, into at least midday, a broad area of strong low-level flow above the surface, and related large low-level shear/hodographs, should extend well east and northeast of center across the outlook area, superimposed over: 1. Relatively maximized low-level convergence, in an arc initially located over eastern SC into southern NC, preceded by well-backed surface winds, and forecast to shift northward to northeastward today; 2. A richly moist, high-theta-e and weak-MLCINH boundary layer advecting inland from the Atlantic and characterized by surface dewpoints commonly in the 70s F. These conditions will yield a favorable environment for tornadoes from any supercells that can cross it, whether within or ahead of the main spiral/convergence band. The most probable area for several supercells to interact with this favorable airmass is over the 10%/"enhanced" tornado-risk area, with potential decreasing westward and northward from there due to weaker instability. Although the supportive low-level airmass will continue to shift northeastward over eastern NC and south-central/southeastern VA this afternoon, tornado potential will diminish with time from midafternoon into early evening. This will occur as convection decreases in coverage and intensity across the area due to a combination of weakening lift and shear, as the remnants of Helene decay rapidly and back well westward away from the area. This process will decouple the remaining stronger low-level flow and isallobaric forcing away from the most-favorable boundary layer near the coast, where hodographs should shrink by the hour this afternoon into evening. ..Edwards/Broyles.. 09/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0751 AM CDT Fri Sep 27 2024 Valid 271300Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERNMOST SOUTH CAROLINA OVER PORTIONS OF SOUTHERN/EASTERN NORTH CAROLINA... ...SUMMARY... Tornadoes will be most likely through midday and remain possible into afternoon across parts of the Carolinas and Virginia. ...Synopsis... In mid/upper levels, a zonal to west-southwesterly belt of flow will persist from the northwestern CONUS and western Canada into central Canada, well-removed from a cut-off, cold-core low now evident in moisture-channel imagery over northern MS. This low is expected to pivot slowly northeastward into middle TN by 00Z, then wobble erratically over that area and/or south-central KY through the night as it absorbs the remnant vorticity max from what is now Tropical Storm Helene. ...SC/NC/VA... The path of center of Tropical Storm Helene finally has turned northward. See SPC Tornado watch 688 and associated mesoscale discussions for near-term coverage of the tornado threat over the region. Refer to NHC advisories for the latest track/intensity guidance on Helene. The NHC forecast shows that the center should bend northwestward across southwestern NC, eastern TN and into southern KY through tonight, weakening greatly and becoming more closely conjoined with the mid/upper cyclone. For several more hours, into at least midday, a broad area of strong low-level flow above the surface, and related large low-level shear/hodographs, should extend well east and northeast of center across the outlook area, superimposed over: 1. Relatively maximized low-level convergence, in an arc initially located over eastern SC into southern NC, preceded by well-backed surface winds, and forecast to shift northward to northeastward today; 2. A richly moist, high-theta-e and weak-MLCINH boundary layer advecting inland from the Atlantic and characterized by surface dewpoints commonly in the 70s F. These conditions will yield a favorable environment for tornadoes from any supercells that can cross it, whether within or ahead of the main spiral/convergence band. The most probable area for several supercells to interact with this favorable airmass is over the 10%/"enhanced" tornado-risk area, with potential decreasing westward and northward from there due to weaker instability. Although the supportive low-level airmass will continue to shift northeastward over eastern NC and south-central/southeastern VA this afternoon, tornado potential will diminish with time from midafternoon into early evening. This will occur as convection decreases in coverage and intensity across the area due to a combination of weakening lift and shear, as the remnants of Helene decay rapidly and back well westward away from the area. This process will decouple the remaining stronger low-level flow and isallobaric forcing away from the most-favorable boundary layer near the coast, where hodographs should shrink by the hour this afternoon into evening. ..Edwards/Broyles.. 09/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0751 AM CDT Fri Sep 27 2024 Valid 271300Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERNMOST SOUTH CAROLINA OVER PORTIONS OF SOUTHERN/EASTERN NORTH CAROLINA... ...SUMMARY... Tornadoes will be most likely through midday and remain possible into afternoon across parts of the Carolinas and Virginia. ...Synopsis... In mid/upper levels, a zonal to west-southwesterly belt of flow will persist from the northwestern CONUS and western Canada into central Canada, well-removed from a cut-off, cold-core low now evident in moisture-channel imagery over northern MS. This low is expected to pivot slowly northeastward into middle TN by 00Z, then wobble erratically over that area and/or south-central KY through the night as it absorbs the remnant vorticity max from what is now Tropical Storm Helene. ...SC/NC/VA... The path of center of Tropical Storm Helene finally has turned northward. See SPC Tornado watch 688 and associated mesoscale discussions for near-term coverage of the tornado threat over the region. Refer to NHC advisories for the latest track/intensity guidance on Helene. The NHC forecast shows that the center should bend northwestward across southwestern NC, eastern TN and into southern KY through tonight, weakening greatly and becoming more closely conjoined with the mid/upper cyclone. For several more hours, into at least midday, a broad area of strong low-level flow above the surface, and related large low-level shear/hodographs, should extend well east and northeast of center across the outlook area, superimposed over: 1. Relatively maximized low-level convergence, in an arc initially located over eastern SC into southern NC, preceded by well-backed surface winds, and forecast to shift northward to northeastward today; 2. A richly moist, high-theta-e and weak-MLCINH boundary layer advecting inland from the Atlantic and characterized by surface dewpoints commonly in the 70s F. These conditions will yield a favorable environment for tornadoes from any supercells that can cross it, whether within or ahead of the main spiral/convergence band. The most probable area for several supercells to interact with this favorable airmass is over the 10%/"enhanced" tornado-risk area, with potential decreasing westward and northward from there due to weaker instability. Although the supportive low-level airmass will continue to shift northeastward over eastern NC and south-central/southeastern VA this afternoon, tornado potential will diminish with time from midafternoon into early evening. This will occur as convection decreases in coverage and intensity across the area due to a combination of weakening lift and shear, as the remnants of Helene decay rapidly and back well westward away from the area. This process will decouple the remaining stronger low-level flow and isallobaric forcing away from the most-favorable boundary layer near the coast, where hodographs should shrink by the hour this afternoon into evening. ..Edwards/Broyles.. 09/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0751 AM CDT Fri Sep 27 2024 Valid 271300Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERNMOST SOUTH CAROLINA OVER PORTIONS OF SOUTHERN/EASTERN NORTH CAROLINA... ...SUMMARY... Tornadoes will be most likely through midday and remain possible into afternoon across parts of the Carolinas and Virginia. ...Synopsis... In mid/upper levels, a zonal to west-southwesterly belt of flow will persist from the northwestern CONUS and western Canada into central Canada, well-removed from a cut-off, cold-core low now evident in moisture-channel imagery over northern MS. This low is expected to pivot slowly northeastward into middle TN by 00Z, then wobble erratically over that area and/or south-central KY through the night as it absorbs the remnant vorticity max from what is now Tropical Storm Helene. ...SC/NC/VA... The path of center of Tropical Storm Helene finally has turned northward. See SPC Tornado watch 688 and associated mesoscale discussions for near-term coverage of the tornado threat over the region. Refer to NHC advisories for the latest track/intensity guidance on Helene. The NHC forecast shows that the center should bend northwestward across southwestern NC, eastern TN and into southern KY through tonight, weakening greatly and becoming more closely conjoined with the mid/upper cyclone. For several more hours, into at least midday, a broad area of strong low-level flow above the surface, and related large low-level shear/hodographs, should extend well east and northeast of center across the outlook area, superimposed over: 1. Relatively maximized low-level convergence, in an arc initially located over eastern SC into southern NC, preceded by well-backed surface winds, and forecast to shift northward to northeastward today; 2. A richly moist, high-theta-e and weak-MLCINH boundary layer advecting inland from the Atlantic and characterized by surface dewpoints commonly in the 70s F. These conditions will yield a favorable environment for tornadoes from any supercells that can cross it, whether within or ahead of the main spiral/convergence band. The most probable area for several supercells to interact with this favorable airmass is over the 10%/"enhanced" tornado-risk area, with potential decreasing westward and northward from there due to weaker instability. Although the supportive low-level airmass will continue to shift northeastward over eastern NC and south-central/southeastern VA this afternoon, tornado potential will diminish with time from midafternoon into early evening. This will occur as convection decreases in coverage and intensity across the area due to a combination of weakening lift and shear, as the remnants of Helene decay rapidly and back well westward away from the area. This process will decouple the remaining stronger low-level flow and isallobaric forcing away from the most-favorable boundary layer near the coast, where hodographs should shrink by the hour this afternoon into evening. ..Edwards/Broyles.. 09/27/2024 Read more

WW 0688 Status Updates
STATUS REPORT ON WW 688 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..BROYLES..09/27/24 ATTN...WFO...RAH...MHX...AKQ...ILM...GSP...RNK...CAE... STATUS REPORT FOR WT 688 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NCC001-007-013-015-017-019-025-029-031-033-037-041-047-049-051- 053-055-057-059-061-063-065-067-069-073-077-079-081-083-085-091- 093-095-101-103-105-107-117-119-123-125-127-129-131-133-135-137- 139-141-143-145-147-151-153-155-157-159-163-165-167-169-171-177- 179-181-183-185-187-191-195-197-271340- NC . NORTH CAROLINA COUNTIES INCLUDED ARE ALAMANCE ANSON BEAUFORT BERTIE BLADEN BRUNSWICK CABARRUS CAMDEN CARTERET CASWELL CHATHAM CHOWAN COLUMBUS CRAVEN CUMBERLAND CURRITUCK DARE DAVIDSON DAVIE DUPLIN DURHAM EDGECOMBE FORSYTH FRANKLIN GATES GRANVILLE GREENE GUILFORD HALIFAX HARNETT HERTFORD HOKE HYDE JOHNSTON JONES LEE LENOIR MARTIN MECKLENBURG MONTGOMERY MOORE NASH NEW HANOVER NORTHAMPTON ONSLOW ORANGE PAMLICO PASQUOTANK PENDER PERQUIMANS PERSON Read more

No watches are valid as of Fri Sep 27 12:02:02 UTC 2024.

000
ABPZ20 KNHC 271144
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Fri Sep 27 2024

For the eastern North Pacific...east of 140 degrees west longitude:

Active Systems:
The National Hurricane Center is issuing advisories on Tropical
Storm John, located very near the coast of southwestern Mexico.

Tropical cyclone formation is not expected during the next 7 days.

$$
Forecaster Cangialosi

5-Day Uncertainty Track last updated Fri, 27 Sep 2024 11:40:25 GMT


Wind Speed Probabilities last updated Fri, 27 Sep 2024 09:35:06 GMT

Issued at 600 AM CST Fri Sep 27 2024 000 WTPZ35 KNHC 271140 TCPEP5 BULLETIN Tropical Storm John Intermediate Advisory Number 18A NWS National Hurricane Center Miami FL EP102024 600 AM CST Fri Sep 27 2024 ...JOHN HUGGING THE COAST... ...CATASTROPHIC FLASH FLOODING AND MUDSLIDES CONTINUE OVER PORTIONS OF SOUTHERN AND SOUTHWESTERN MEXICO... SUMMARY OF 600 AM CST...1200 UTC...INFORMATION ---------------------------------------------- LOCATION...17.9N 102.9W ABOUT 50 MI...75 KM WSW OF LAZARO CARDENAS MEXICO ABOUT 120 MI...190 KM SE OF MANZANILLO MEXICO MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/H PRESENT MOVEMENT...NW OR 320 DEGREES AT 5 MPH...7 KM/H MINIMUM CENTRAL PRESSURE...988 MB...29.18 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: None. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Warning is in effect for... * Punta Maldonado to Manzanillo A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area, in this case within the next 12 hours. For storm information specific to your area, please monitor products issued by your national meteorological service. DISCUSSION AND OUTLOOK ---------------------- At 600 AM CST (1200 UTC), the center of Tropical Storm John was located near latitude 17.9 North, longitude 102.9 West. John is moving toward the northwest near 5 mph (7 km/h) and this motion is expected to continue through today. On the forecast track, the center of John is forecast to move along the coast or just inland of southwestern Mexico later today and tonight. Maximum sustained winds are near 65 mph (100 km/h) with higher gusts. Gradual weakening is expected today, with a faster rate of weakening forecast by tonight while the center begins to interact with the higher terrain of the Sierra Madre Del Sur mountains. Tropical-storm-force winds extend outward up to 160 miles (260 km) from the center. The estimated minimum central pressure is 988 mb (29.18 inches). HAZARDS AFFECTING LAND ---------------------- RAINFALL: Through today, Tropical Storm John is expected to produce rainfall amounts of 10 to 20 inches across portions of the Mexican States of Guerrero and Michoacán. Additional rainfall of 2 to 4 inches with locally up to 6 inches expected across the Mexican States of Colima and western Oaxaca. For a complete depiction of forecast rainfall associated with John, please see the National Weather Service Storm Total Rainfall Graphic, available at hurricanes.gov/graphics_ep5.shtml?rainqpf STORM SURGE: Storm surge is likely to produce coastal flooding near and to the east of where the center makes landfall. Near the coast, the surge will be accompanied by large waves. WIND: Tropical storm conditions are expected to continue across coastal portions of the Tropical Storm Warning area through today. SURF: Swells associated with John are forecast to continue to affect the coast of southern and southwestern Mexico through tonight into Saturday, with the potential for dangerous surf and rip currents. Please see local statements for more information. NEXT ADVISORY ------------- Next complete advisory at 900 AM CST. $$ Forecaster Kelly/Rosado

...JOHN HUGGING THE COAST... ...CATASTROPHIC FLASH FLOODING AND MUDSLIDES CONTINUE OVER PORTIONS OF SOUTHERN AND SOUTHWESTERN MEXICO... As of 6:00 AM CST Fri Sep 27 the center of John was located near 17.9, -102.9 with movement NW at 5 mph. The minimum central pressure was 988 mb with maximum sustained winds of about 65 mph.

MD 2123 CONCERNING TORNADO WATCH 686...687... FOR EASTERN GEORGIA...SOUTH CAROLINA...SOUTHERN NORTH CAROLINA
Mesoscale Discussion 2123 NWS Storm Prediction Center Norman OK 0417 AM CDT Fri Sep 27 2024 Areas affected...Eastern Georgia...South Carolina...Southern North Carolina Concerning...Tornado Watch 686...687... Valid 270917Z - 271115Z The severe weather threat for Tornado Watch 686, 687 continues. SUMMARY...A tornado threat will continue tonight from eastern Georgia into South Carolina and southern North Carolina. DISCUSSION...Tropical Storm Helene is currently moving northward through east-central Georgia. Mosaic radar imagery shows that rainbands extend outward up to 200 statute miles to the north of Helene. Within these rainbands, several discrete cells are ongoing across eastern South Carolina, where the tornado threat is maximized at this time. The WSR-88D VWP at Wilmington, North Carolina appears representative of the environment from the middle South Carolina coast northward to Wilmington, and has 0-6 km shear near 50 knots with 0-3 km storm-relative helicity in the 400 to 500 m2/s2 range. This will continue to support a tornado threat as thunderstorms move north-northwestward across South Carolina over the next several hours. The tornado threat should gradually move northward into southern and central North Carolina. ..Broyles.. 09/27/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...RAH...ILM...CHS...CAE...GSP...JAX...FFC... LAT...LON 33418209 32168234 31598175 31308129 31258061 32037973 32227954 33227865 33927827 34607829 35017883 35147995 34998102 34218187 33418209 Read more