Severe Storms

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Mon Sep 16 2024 Valid 171200Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN THE CENTRAL HIGH PLAINS AND EASTERN MT... ...SUMMARY... Isolated to scattered severe gusts and hail are possible Tuesday across a large swath of the High Plains region, mainly from late afternoon into the evening. The greater concentrations of severe storms may occur over the central High Plains and eastern Montana. ...High Plains... A mid/upper-level shortwave trough initially over the eastern Great Basin will take on a negative tilt as it advances towards the northern High Plains. Deep lee cyclogenesis is expected over far northeast WY/southeast MT, with a warm front arcing east across parts of the Dakotas. This low will advance north then northwestward across eastern MT through 12Z Wednesday. Large-scale ascent will be pronounced within this synoptic regime, with favorable upper-level difluence, mid-level height falls, and low-level convergence. However, weak buoyancy and modest mid-level lapse rates will characterize much of the environment to the south of the surface cyclone and warm front. Aided by a subtropical moisture plume over the Southwest, morning convection near the Four Corners region should move across the higher terrain and expand in coverage into the afternoon. High-based storms over the central and southern High Plains will progress into a well-mixed boundary layer that may initially be devoid of appreciable CAPE. This lack of greater buoyancy during the late afternoon to early evening (outside of areas north of the warm front) yields some uncertainty regarding the degree of storm intensity into the lower elevations. But with scattered to eventually widespread convection expected with time, extensive outflows are expected to push east. The most likely corridor for severe gusts appears to be over the central High Plains where the most pronounced 700-500 mb flow should advance ahead of the negative-tilt shortwave trough. Farther south, a few supercells may initially develop from parts of NM into southeast CO. Modest mid-level lapse rates should temper updraft vigor, but marginally severe hail along with isolated severe gusts will be possible. More favorable low-level moisture with steep mid-level lapse rates will reside near/north of the warm front, supporting moderate buoyancy from northeast MT into ND. While stronger ascent and deep-layer flow may not impinge upon areas north of the front until near sunset, organized storms should develop over the higher terrain by late afternoon and spread north within a backed mid-level flow regime. A few supercells along with an organized cluster or two may impinge on the greater downstream buoyancy plume, maintaining threats for large hail and severe gusts into Tuesday night. ...Eastern NC and southeast VA... While confidence is modest with the probable inland evolution of PTC 8, the bulk signal across guidance is for a weakening low-level wind field by Tuesday morning across the NC/VA coastal plain. The potential for low-topped supercells capable of brief tornadoes appears too low beyond 12Z Tuesday to warrant a risk highlight. ..Grams.. 09/16/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Mon Sep 16 2024 Valid 171200Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN THE CENTRAL HIGH PLAINS AND EASTERN MT... ...SUMMARY... Isolated to scattered severe gusts and hail are possible Tuesday across a large swath of the High Plains region, mainly from late afternoon into the evening. The greater concentrations of severe storms may occur over the central High Plains and eastern Montana. ...High Plains... A mid/upper-level shortwave trough initially over the eastern Great Basin will take on a negative tilt as it advances towards the northern High Plains. Deep lee cyclogenesis is expected over far northeast WY/southeast MT, with a warm front arcing east across parts of the Dakotas. This low will advance north then northwestward across eastern MT through 12Z Wednesday. Large-scale ascent will be pronounced within this synoptic regime, with favorable upper-level difluence, mid-level height falls, and low-level convergence. However, weak buoyancy and modest mid-level lapse rates will characterize much of the environment to the south of the surface cyclone and warm front. Aided by a subtropical moisture plume over the Southwest, morning convection near the Four Corners region should move across the higher terrain and expand in coverage into the afternoon. High-based storms over the central and southern High Plains will progress into a well-mixed boundary layer that may initially be devoid of appreciable CAPE. This lack of greater buoyancy during the late afternoon to early evening (outside of areas north of the warm front) yields some uncertainty regarding the degree of storm intensity into the lower elevations. But with scattered to eventually widespread convection expected with time, extensive outflows are expected to push east. The most likely corridor for severe gusts appears to be over the central High Plains where the most pronounced 700-500 mb flow should advance ahead of the negative-tilt shortwave trough. Farther south, a few supercells may initially develop from parts of NM into southeast CO. Modest mid-level lapse rates should temper updraft vigor, but marginally severe hail along with isolated severe gusts will be possible. More favorable low-level moisture with steep mid-level lapse rates will reside near/north of the warm front, supporting moderate buoyancy from northeast MT into ND. While stronger ascent and deep-layer flow may not impinge upon areas north of the front until near sunset, organized storms should develop over the higher terrain by late afternoon and spread north within a backed mid-level flow regime. A few supercells along with an organized cluster or two may impinge on the greater downstream buoyancy plume, maintaining threats for large hail and severe gusts into Tuesday night. ...Eastern NC and southeast VA... While confidence is modest with the probable inland evolution of PTC 8, the bulk signal across guidance is for a weakening low-level wind field by Tuesday morning across the NC/VA coastal plain. The potential for low-topped supercells capable of brief tornadoes appears too low beyond 12Z Tuesday to warrant a risk highlight. ..Grams.. 09/16/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Mon Sep 16 2024 Valid 171200Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN THE CENTRAL HIGH PLAINS AND EASTERN MT... ...SUMMARY... Isolated to scattered severe gusts and hail are possible Tuesday across a large swath of the High Plains region, mainly from late afternoon into the evening. The greater concentrations of severe storms may occur over the central High Plains and eastern Montana. ...High Plains... A mid/upper-level shortwave trough initially over the eastern Great Basin will take on a negative tilt as it advances towards the northern High Plains. Deep lee cyclogenesis is expected over far northeast WY/southeast MT, with a warm front arcing east across parts of the Dakotas. This low will advance north then northwestward across eastern MT through 12Z Wednesday. Large-scale ascent will be pronounced within this synoptic regime, with favorable upper-level difluence, mid-level height falls, and low-level convergence. However, weak buoyancy and modest mid-level lapse rates will characterize much of the environment to the south of the surface cyclone and warm front. Aided by a subtropical moisture plume over the Southwest, morning convection near the Four Corners region should move across the higher terrain and expand in coverage into the afternoon. High-based storms over the central and southern High Plains will progress into a well-mixed boundary layer that may initially be devoid of appreciable CAPE. This lack of greater buoyancy during the late afternoon to early evening (outside of areas north of the warm front) yields some uncertainty regarding the degree of storm intensity into the lower elevations. But with scattered to eventually widespread convection expected with time, extensive outflows are expected to push east. The most likely corridor for severe gusts appears to be over the central High Plains where the most pronounced 700-500 mb flow should advance ahead of the negative-tilt shortwave trough. Farther south, a few supercells may initially develop from parts of NM into southeast CO. Modest mid-level lapse rates should temper updraft vigor, but marginally severe hail along with isolated severe gusts will be possible. More favorable low-level moisture with steep mid-level lapse rates will reside near/north of the warm front, supporting moderate buoyancy from northeast MT into ND. While stronger ascent and deep-layer flow may not impinge upon areas north of the front until near sunset, organized storms should develop over the higher terrain by late afternoon and spread north within a backed mid-level flow regime. A few supercells along with an organized cluster or two may impinge on the greater downstream buoyancy plume, maintaining threats for large hail and severe gusts into Tuesday night. ...Eastern NC and southeast VA... While confidence is modest with the probable inland evolution of PTC 8, the bulk signal across guidance is for a weakening low-level wind field by Tuesday morning across the NC/VA coastal plain. The potential for low-topped supercells capable of brief tornadoes appears too low beyond 12Z Tuesday to warrant a risk highlight. ..Grams.. 09/16/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Mon Sep 16 2024 Valid 161200Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN PLAINS... ...SUMMARY... Thunderstorms capable of severe gusts and large hail are expected today in parts of the northern Plains. An isolated tornado threat is expected in the Carolinas. Marginally severe wind and hail may occur in parts of the Four Corners and Intermountain West. ...Northern Plains... Southwest mid-level flow will be in place across the north-central U.S. today. A shortwave trough is forecast to move across North Dakota this afternoon. At the surface, a low will deepen across southeast Montana as a warm front moves northward across central and eastern North Dakota. Surface dewpoints near the front will be in the mid to upper 60s F and moderate instability is expected to develop by afternoon. The front will be a focus for convective initiation from late this morning into the afternoon. RAP forecast soundings near the front in east-central North Dakota have 0-6 km shear in the 30 to 35 knot range with some directional shear in the boundary layer. Mid-level lapse rates are forecast to be between 7.5 and 8 C/km. This environment should support supercells with severe gusts and large hail. The event will be driven by mesoscale processes, and the greatest severe threat coverage will likely be located in areas where the maxima in low-level convergence, instability and deep-layer shear become juxtaposed. The severe threat may ramp up during the early evening as a 40 to 50 knot low-level jet strengthens across the northern Plains. ...Eastern North Carolina/Far Eastern South Carolina... A low pressure area off the coast of the Carolinas is forecast to become a tropical storm by the National Hurricane Center and move northwestward into far eastern South Carolina this evening. RAP forecast soundings to the right of the expected landfall at Wilmington, North Carolina have 0-3 km storm-relative helicity increasing to around 150 m2/s2 by early evening with 0-1 km shear reaching the 20 to 25 knot range. This should support an isolated tornado threat as the tropical storm moves inland this evening. This threat may continue into the late evening and overnight along the coast of North Carolina, where moderate instability is forecast. ...Four Corners/Intermountain West... An mid-level low will move northeastward across the Intermountain West today. Ahead of the system, a band of strong large-scale ascent will aid thunderstorm development from the Four Corners region northwestward across parts of Utah. Scattered storms will likely develop and move northeastward across the region during the afternoon. Although instability will remain weak, very steep lapse rates and strong deep-layer shear may support an isolated severe threat. Marginally severe wind and hail will be possible with the stronger cells. ..Broyles/Weinman.. 09/16/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Mon Sep 16 2024 Valid 161200Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN PLAINS... ...SUMMARY... Thunderstorms capable of severe gusts and large hail are expected today in parts of the northern Plains. An isolated tornado threat is expected in the Carolinas. Marginally severe wind and hail may occur in parts of the Four Corners and Intermountain West. ...Northern Plains... Southwest mid-level flow will be in place across the north-central U.S. today. A shortwave trough is forecast to move across North Dakota this afternoon. At the surface, a low will deepen across southeast Montana as a warm front moves northward across central and eastern North Dakota. Surface dewpoints near the front will be in the mid to upper 60s F and moderate instability is expected to develop by afternoon. The front will be a focus for convective initiation from late this morning into the afternoon. RAP forecast soundings near the front in east-central North Dakota have 0-6 km shear in the 30 to 35 knot range with some directional shear in the boundary layer. Mid-level lapse rates are forecast to be between 7.5 and 8 C/km. This environment should support supercells with severe gusts and large hail. The event will be driven by mesoscale processes, and the greatest severe threat coverage will likely be located in areas where the maxima in low-level convergence, instability and deep-layer shear become juxtaposed. The severe threat may ramp up during the early evening as a 40 to 50 knot low-level jet strengthens across the northern Plains. ...Eastern North Carolina/Far Eastern South Carolina... A low pressure area off the coast of the Carolinas is forecast to become a tropical storm by the National Hurricane Center and move northwestward into far eastern South Carolina this evening. RAP forecast soundings to the right of the expected landfall at Wilmington, North Carolina have 0-3 km storm-relative helicity increasing to around 150 m2/s2 by early evening with 0-1 km shear reaching the 20 to 25 knot range. This should support an isolated tornado threat as the tropical storm moves inland this evening. This threat may continue into the late evening and overnight along the coast of North Carolina, where moderate instability is forecast. ...Four Corners/Intermountain West... An mid-level low will move northeastward across the Intermountain West today. Ahead of the system, a band of strong large-scale ascent will aid thunderstorm development from the Four Corners region northwestward across parts of Utah. Scattered storms will likely develop and move northeastward across the region during the afternoon. Although instability will remain weak, very steep lapse rates and strong deep-layer shear may support an isolated severe threat. Marginally severe wind and hail will be possible with the stronger cells. ..Broyles/Weinman.. 09/16/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Mon Sep 16 2024 Valid 161200Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN PLAINS... ...SUMMARY... Thunderstorms capable of severe gusts and large hail are expected today in parts of the northern Plains. An isolated tornado threat is expected in the Carolinas. Marginally severe wind and hail may occur in parts of the Four Corners and Intermountain West. ...Northern Plains... Southwest mid-level flow will be in place across the north-central U.S. today. A shortwave trough is forecast to move across North Dakota this afternoon. At the surface, a low will deepen across southeast Montana as a warm front moves northward across central and eastern North Dakota. Surface dewpoints near the front will be in the mid to upper 60s F and moderate instability is expected to develop by afternoon. The front will be a focus for convective initiation from late this morning into the afternoon. RAP forecast soundings near the front in east-central North Dakota have 0-6 km shear in the 30 to 35 knot range with some directional shear in the boundary layer. Mid-level lapse rates are forecast to be between 7.5 and 8 C/km. This environment should support supercells with severe gusts and large hail. The event will be driven by mesoscale processes, and the greatest severe threat coverage will likely be located in areas where the maxima in low-level convergence, instability and deep-layer shear become juxtaposed. The severe threat may ramp up during the early evening as a 40 to 50 knot low-level jet strengthens across the northern Plains. ...Eastern North Carolina/Far Eastern South Carolina... A low pressure area off the coast of the Carolinas is forecast to become a tropical storm by the National Hurricane Center and move northwestward into far eastern South Carolina this evening. RAP forecast soundings to the right of the expected landfall at Wilmington, North Carolina have 0-3 km storm-relative helicity increasing to around 150 m2/s2 by early evening with 0-1 km shear reaching the 20 to 25 knot range. This should support an isolated tornado threat as the tropical storm moves inland this evening. This threat may continue into the late evening and overnight along the coast of North Carolina, where moderate instability is forecast. ...Four Corners/Intermountain West... An mid-level low will move northeastward across the Intermountain West today. Ahead of the system, a band of strong large-scale ascent will aid thunderstorm development from the Four Corners region northwestward across parts of Utah. Scattered storms will likely develop and move northeastward across the region during the afternoon. Although instability will remain weak, very steep lapse rates and strong deep-layer shear may support an isolated severe threat. Marginally severe wind and hail will be possible with the stronger cells. ..Broyles/Weinman.. 09/16/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Mon Sep 16 2024 Valid 161200Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN PLAINS... ...SUMMARY... Thunderstorms capable of severe gusts and large hail are expected today in parts of the northern Plains. An isolated tornado threat is expected in the Carolinas. Marginally severe wind and hail may occur in parts of the Four Corners and Intermountain West. ...Northern Plains... Southwest mid-level flow will be in place across the north-central U.S. today. A shortwave trough is forecast to move across North Dakota this afternoon. At the surface, a low will deepen across southeast Montana as a warm front moves northward across central and eastern North Dakota. Surface dewpoints near the front will be in the mid to upper 60s F and moderate instability is expected to develop by afternoon. The front will be a focus for convective initiation from late this morning into the afternoon. RAP forecast soundings near the front in east-central North Dakota have 0-6 km shear in the 30 to 35 knot range with some directional shear in the boundary layer. Mid-level lapse rates are forecast to be between 7.5 and 8 C/km. This environment should support supercells with severe gusts and large hail. The event will be driven by mesoscale processes, and the greatest severe threat coverage will likely be located in areas where the maxima in low-level convergence, instability and deep-layer shear become juxtaposed. The severe threat may ramp up during the early evening as a 40 to 50 knot low-level jet strengthens across the northern Plains. ...Eastern North Carolina/Far Eastern South Carolina... A low pressure area off the coast of the Carolinas is forecast to become a tropical storm by the National Hurricane Center and move northwestward into far eastern South Carolina this evening. RAP forecast soundings to the right of the expected landfall at Wilmington, North Carolina have 0-3 km storm-relative helicity increasing to around 150 m2/s2 by early evening with 0-1 km shear reaching the 20 to 25 knot range. This should support an isolated tornado threat as the tropical storm moves inland this evening. This threat may continue into the late evening and overnight along the coast of North Carolina, where moderate instability is forecast. ...Four Corners/Intermountain West... An mid-level low will move northeastward across the Intermountain West today. Ahead of the system, a band of strong large-scale ascent will aid thunderstorm development from the Four Corners region northwestward across parts of Utah. Scattered storms will likely develop and move northeastward across the region during the afternoon. Although instability will remain weak, very steep lapse rates and strong deep-layer shear may support an isolated severe threat. Marginally severe wind and hail will be possible with the stronger cells. ..Broyles/Weinman.. 09/16/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Mon Sep 16 2024 Valid 161200Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN PLAINS... ...SUMMARY... Thunderstorms capable of severe gusts and large hail are expected today in parts of the northern Plains. An isolated tornado threat is expected in the Carolinas. Marginally severe wind and hail may occur in parts of the Four Corners and Intermountain West. ...Northern Plains... Southwest mid-level flow will be in place across the north-central U.S. today. A shortwave trough is forecast to move across North Dakota this afternoon. At the surface, a low will deepen across southeast Montana as a warm front moves northward across central and eastern North Dakota. Surface dewpoints near the front will be in the mid to upper 60s F and moderate instability is expected to develop by afternoon. The front will be a focus for convective initiation from late this morning into the afternoon. RAP forecast soundings near the front in east-central North Dakota have 0-6 km shear in the 30 to 35 knot range with some directional shear in the boundary layer. Mid-level lapse rates are forecast to be between 7.5 and 8 C/km. This environment should support supercells with severe gusts and large hail. The event will be driven by mesoscale processes, and the greatest severe threat coverage will likely be located in areas where the maxima in low-level convergence, instability and deep-layer shear become juxtaposed. The severe threat may ramp up during the early evening as a 40 to 50 knot low-level jet strengthens across the northern Plains. ...Eastern North Carolina/Far Eastern South Carolina... A low pressure area off the coast of the Carolinas is forecast to become a tropical storm by the National Hurricane Center and move northwestward into far eastern South Carolina this evening. RAP forecast soundings to the right of the expected landfall at Wilmington, North Carolina have 0-3 km storm-relative helicity increasing to around 150 m2/s2 by early evening with 0-1 km shear reaching the 20 to 25 knot range. This should support an isolated tornado threat as the tropical storm moves inland this evening. This threat may continue into the late evening and overnight along the coast of North Carolina, where moderate instability is forecast. ...Four Corners/Intermountain West... An mid-level low will move northeastward across the Intermountain West today. Ahead of the system, a band of strong large-scale ascent will aid thunderstorm development from the Four Corners region northwestward across parts of Utah. Scattered storms will likely develop and move northeastward across the region during the afternoon. Although instability will remain weak, very steep lapse rates and strong deep-layer shear may support an isolated severe threat. Marginally severe wind and hail will be possible with the stronger cells. ..Broyles/Weinman.. 09/16/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Mon Sep 16 2024 Valid 161200Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN PLAINS... ...SUMMARY... Thunderstorms capable of severe gusts and large hail are expected today in parts of the northern Plains. An isolated tornado threat is expected in the Carolinas. Marginally severe wind and hail may occur in parts of the Four Corners and Intermountain West. ...Northern Plains... Southwest mid-level flow will be in place across the north-central U.S. today. A shortwave trough is forecast to move across North Dakota this afternoon. At the surface, a low will deepen across southeast Montana as a warm front moves northward across central and eastern North Dakota. Surface dewpoints near the front will be in the mid to upper 60s F and moderate instability is expected to develop by afternoon. The front will be a focus for convective initiation from late this morning into the afternoon. RAP forecast soundings near the front in east-central North Dakota have 0-6 km shear in the 30 to 35 knot range with some directional shear in the boundary layer. Mid-level lapse rates are forecast to be between 7.5 and 8 C/km. This environment should support supercells with severe gusts and large hail. The event will be driven by mesoscale processes, and the greatest severe threat coverage will likely be located in areas where the maxima in low-level convergence, instability and deep-layer shear become juxtaposed. The severe threat may ramp up during the early evening as a 40 to 50 knot low-level jet strengthens across the northern Plains. ...Eastern North Carolina/Far Eastern South Carolina... A low pressure area off the coast of the Carolinas is forecast to become a tropical storm by the National Hurricane Center and move northwestward into far eastern South Carolina this evening. RAP forecast soundings to the right of the expected landfall at Wilmington, North Carolina have 0-3 km storm-relative helicity increasing to around 150 m2/s2 by early evening with 0-1 km shear reaching the 20 to 25 knot range. This should support an isolated tornado threat as the tropical storm moves inland this evening. This threat may continue into the late evening and overnight along the coast of North Carolina, where moderate instability is forecast. ...Four Corners/Intermountain West... An mid-level low will move northeastward across the Intermountain West today. Ahead of the system, a band of strong large-scale ascent will aid thunderstorm development from the Four Corners region northwestward across parts of Utah. Scattered storms will likely develop and move northeastward across the region during the afternoon. Although instability will remain weak, very steep lapse rates and strong deep-layer shear may support an isolated severe threat. Marginally severe wind and hail will be possible with the stronger cells. ..Broyles/Weinman.. 09/16/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Mon Sep 16 2024 Valid 161200Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN PLAINS... ...SUMMARY... Thunderstorms capable of severe gusts and large hail are expected today in parts of the northern Plains. An isolated tornado threat is expected in the Carolinas. Marginally severe wind and hail may occur in parts of the Four Corners and Intermountain West. ...Northern Plains... Southwest mid-level flow will be in place across the north-central U.S. today. A shortwave trough is forecast to move across North Dakota this afternoon. At the surface, a low will deepen across southeast Montana as a warm front moves northward across central and eastern North Dakota. Surface dewpoints near the front will be in the mid to upper 60s F and moderate instability is expected to develop by afternoon. The front will be a focus for convective initiation from late this morning into the afternoon. RAP forecast soundings near the front in east-central North Dakota have 0-6 km shear in the 30 to 35 knot range with some directional shear in the boundary layer. Mid-level lapse rates are forecast to be between 7.5 and 8 C/km. This environment should support supercells with severe gusts and large hail. The event will be driven by mesoscale processes, and the greatest severe threat coverage will likely be located in areas where the maxima in low-level convergence, instability and deep-layer shear become juxtaposed. The severe threat may ramp up during the early evening as a 40 to 50 knot low-level jet strengthens across the northern Plains. ...Eastern North Carolina/Far Eastern South Carolina... A low pressure area off the coast of the Carolinas is forecast to become a tropical storm by the National Hurricane Center and move northwestward into far eastern South Carolina this evening. RAP forecast soundings to the right of the expected landfall at Wilmington, North Carolina have 0-3 km storm-relative helicity increasing to around 150 m2/s2 by early evening with 0-1 km shear reaching the 20 to 25 knot range. This should support an isolated tornado threat as the tropical storm moves inland this evening. This threat may continue into the late evening and overnight along the coast of North Carolina, where moderate instability is forecast. ...Four Corners/Intermountain West... An mid-level low will move northeastward across the Intermountain West today. Ahead of the system, a band of strong large-scale ascent will aid thunderstorm development from the Four Corners region northwestward across parts of Utah. Scattered storms will likely develop and move northeastward across the region during the afternoon. Although instability will remain weak, very steep lapse rates and strong deep-layer shear may support an isolated severe threat. Marginally severe wind and hail will be possible with the stronger cells. ..Broyles/Weinman.. 09/16/2024 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0737 PM CDT Sun Sep 15 2024 Valid 160100Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN PLAINS... ...SUMMARY... Thunderstorms capable of producing isolated severe gusts and hail may occur this evening across parts of the central and northern Plains. ...Central and Northern Plains... Southwest mid-level flow is evident on water vapor imagery over the western U.S., with a subtle shortwave trough moving through the central Rockies. Ahead of the trough, a moist airmass is located over much of the central and northern Plains, where surface dewpoints are generally in the lower to mid 60s F. Due to surface heating, most of the airmass has become moderately unstable. Scattered thunderstorms are ongoing along the western edge of the moist airmass from eastern Colorado into southwest Nebraska and eastern Wyoming. This activity will continue to move northeastward across the central and northern High Plains this evening, with a gradual expansion in coverage expected. WSR-88D VWPs near the instability axis have supercell wind profiles, with veering winds in the low-levels and 0-6 km shear in the 35 to 40 knot range. In addition, forecast soundings have low to mid-level lapse rates around 8 C/km, which is also evident on the 00Z Rapid City sounding. This environment will support an isolated severe threat this evening. Hail and marginally severe wind gusts will be the primary threats. ..Broyles.. 09/16/2024 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0737 PM CDT Sun Sep 15 2024 Valid 160100Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN PLAINS... ...SUMMARY... Thunderstorms capable of producing isolated severe gusts and hail may occur this evening across parts of the central and northern Plains. ...Central and Northern Plains... Southwest mid-level flow is evident on water vapor imagery over the western U.S., with a subtle shortwave trough moving through the central Rockies. Ahead of the trough, a moist airmass is located over much of the central and northern Plains, where surface dewpoints are generally in the lower to mid 60s F. Due to surface heating, most of the airmass has become moderately unstable. Scattered thunderstorms are ongoing along the western edge of the moist airmass from eastern Colorado into southwest Nebraska and eastern Wyoming. This activity will continue to move northeastward across the central and northern High Plains this evening, with a gradual expansion in coverage expected. WSR-88D VWPs near the instability axis have supercell wind profiles, with veering winds in the low-levels and 0-6 km shear in the 35 to 40 knot range. In addition, forecast soundings have low to mid-level lapse rates around 8 C/km, which is also evident on the 00Z Rapid City sounding. This environment will support an isolated severe threat this evening. Hail and marginally severe wind gusts will be the primary threats. ..Broyles.. 09/16/2024 Read more

MD 2068 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF NORTHEASTERN CO...WESTERN NE...EASTERN WY...AND SOUTHWESTERN SD
Mesoscale Discussion 2068 NWS Storm Prediction Center Norman OK 0500 PM CDT Sun Sep 15 2024 Areas affected...portions of northeastern CO...western NE...eastern WY...and southwestern SD Concerning...Severe potential...Watch unlikely Valid 152200Z - 160030Z Probability of Watch Issuance...20 percent SUMMARY...Thunderstorms should increase in strength and coverage while spreading/developing northward across the central/northern High Plains into this evening. The strongest storms will be capable of producing severe wind gusts and isolated large hail. DISCUSSION...Latest water-vapor imagery depicts an embedded midlevel impulse tracking northeastward across portions of northern CO this afternoon, and regional VWP shows around 20-30-kt midlevel flow accompanying this feature. Associated large-scale ascent will promote an increase in thunderstorm development along the central/northern High Plains -- generally focused on the moist side of a lee trough. Steep deep-layer lapse rates (sampled by recent DEN ACARS soundings) amid lower/middle 50s dewpoints are contributing to sufficient buoyancy for gradual updraft intensification. Additionally, the enhanced midlevel southwesterly flow atop low-level southeasterlies is favoring 20-30 kt of effective shear -- sufficient for loosely organized clusters and brief supercell structures. As as result, severe winds gusts and isolated large hail will be possible with the strongest storms as they spread/develop northward into this evening. Given the increasing large-scale ascent and favorable environment for strong convective outflow generation, there may be a tendency for localized upscale growth with time, which would further increase the severe-wind risk. Current expectation is for the marginal deep-layer shear to limit overall convective organization and intensity, and a watch is not currently expected. However, convective trends will be monitored into this evening. ..Weinman/Guyer.. 09/15/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...UNR...GLD...BOU...CYS... LAT...LON 39840198 39800232 40300445 40580467 41730491 42500495 44300429 44540405 44610364 44500315 43990281 43460267 42640275 41560262 40150177 39840198 Read more

No watches are valid as of Sun Sep 15 22:30:02 UTC 2024.

MD 2068 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF NORTHEASTERN CO...WESTERN NE...EASTERN WY...AND SOUTHWESTERN SD
Mesoscale Discussion 2068 NWS Storm Prediction Center Norman OK 0500 PM CDT Sun Sep 15 2024 Areas affected...portions of northeastern CO...western NE...eastern WY...and southwestern SD Concerning...Severe potential...Watch unlikely Valid 152200Z - 160030Z Probability of Watch Issuance...20 percent SUMMARY...Thunderstorms should increase in strength and coverage while spreading/developing northward across the central/northern High Plains into this evening. The strongest storms will be capable of producing severe wind gusts and isolated large hail. DISCUSSION...Latest water-vapor imagery depicts an embedded midlevel impulse tracking northeastward across portions of northern CO this afternoon, and regional VWP shows around 20-30-kt midlevel flow accompanying this feature. Associated large-scale ascent will promote an increase in thunderstorm development along the central/northern High Plains -- generally focused on the moist side of a lee trough. Steep deep-layer lapse rates (sampled by recent DEN ACARS soundings) amid lower/middle 50s dewpoints are contributing to sufficient buoyancy for gradual updraft intensification. Additionally, the enhanced midlevel southwesterly flow atop low-level southeasterlies is favoring 20-30 kt of effective shear -- sufficient for loosely organized clusters and brief supercell structures. As as result, severe winds gusts and isolated large hail will be possible with the strongest storms as they spread/develop northward into this evening. Given the increasing large-scale ascent and favorable environment for strong convective outflow generation, there may be a tendency for localized upscale growth with time, which would further increase the severe-wind risk. Current expectation is for the marginal deep-layer shear to limit overall convective organization and intensity, and a watch is not currently expected. However, convective trends will be monitored into this evening. ..Weinman/Guyer.. 09/15/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...UNR...GLD...BOU...CYS... LAT...LON 39840198 39800232 40300445 40580467 41730491 42500495 44300429 44540405 44610364 44500315 43990281 43460267 42640275 41560262 40150177 39840198 Read more

No Mesoscale Discussions are in effect as of Sun Sep 15 21:33:01 UTC 2024.

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0248 PM CDT Sun Sep 15 2024 Valid 152000Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS... ...SUMMARY... Thunderstorms capable of producing isolated severe gusts and hail may occur today and tonight across parts of the northern/central Plains. ...20z Update... Only minor adjustments were made to the D1 Convective Outlook to account for latest observational trends. See previous discussion below for more information. ..Thornton/Gleason.. 09/15/2024 .PREV DISCUSSION... /ISSUED 1128 AM CDT Sun Sep 15 2024/ ...Northern/Central Plains... An amplified upper trough along/near the West Coast this morning will further evolve into a closed upper low over northern CA and vicinity by late tonight. Ahead of this feature, modestly enhanced south-southwesterly mid-level flow will be in place over much of the western states and Rockies through the period. Although low-level moisture is expected to remain limited over much of this region, isolated strong to severe gusts may occur with any thunderstorms that can develop in a deeply mixed boundary layer favorable for gusty downdraft winds. Latest guidance continues to suggest that a relatively greater concentration of severe potential will be focused across parts of the northern/central Plains late this afternoon through tonight. Across this area, a weak surface lee trough and greater low-level moisture to its east should support weak to moderate instability with daytime heating. Steep mid-level lapse rates should also aid updraft accelerations/intensities, with around 20-30 kt of deep-layer shear supporting modest thunderstorm organization. Isolated severe hail may occur with initially more discrete convection, but a tendency for clustering should lead to a relatively greater wind threat with time as convection spreads generally east-northeastward through the evening. Regardless, the overall severe threat from northeast CO into western NE/SD and vicinity should remain fairly isolated/marginal given the modest deep-layer shear. Low-level warm advection is forecast to increase across much of the northern/central Plains tonight as a southerly low-level jet strengthens. A surface warm front is also expected to lift northward over ND late tonight into early Monday morning. With steepening mid-level lapse rates overspreading the northern Plains in tandem with increasing low-level moisture, ample MUCAPE should be available. Most guidance shows at least isolated convection developing across parts of ND tonight in this favorable thermodynamic environment. Although deep-layer shear may remain fairly modest, it may still be sufficient for updraft organization and an isolated threat for severe hail with any elevated convection that can form. Have therefore expanded the Marginal Risk northward to account for this potential. ...Coastal Carolinas... Latest NHC forecast continues to indicate some potential for sub-tropical or tropical development of a surface low currently off the SC Coast. Regardless of development, it still appears that the more moist/tropical low-level airmass over the Gulf Stream will struggle to advance inland over coastal portions of NC/SC through the end of the Day 1 forecast period early Monday morning (16/12Z). Accordingly, tornado potential with any low-topped supercells on the north to northeast periphery of the surface low should tend to remain offshore until Day 2/Monday (after 16/12Z). Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0248 PM CDT Sun Sep 15 2024 Valid 152000Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS... ...SUMMARY... Thunderstorms capable of producing isolated severe gusts and hail may occur today and tonight across parts of the northern/central Plains. ...20z Update... Only minor adjustments were made to the D1 Convective Outlook to account for latest observational trends. See previous discussion below for more information. ..Thornton/Gleason.. 09/15/2024 .PREV DISCUSSION... /ISSUED 1128 AM CDT Sun Sep 15 2024/ ...Northern/Central Plains... An amplified upper trough along/near the West Coast this morning will further evolve into a closed upper low over northern CA and vicinity by late tonight. Ahead of this feature, modestly enhanced south-southwesterly mid-level flow will be in place over much of the western states and Rockies through the period. Although low-level moisture is expected to remain limited over much of this region, isolated strong to severe gusts may occur with any thunderstorms that can develop in a deeply mixed boundary layer favorable for gusty downdraft winds. Latest guidance continues to suggest that a relatively greater concentration of severe potential will be focused across parts of the northern/central Plains late this afternoon through tonight. Across this area, a weak surface lee trough and greater low-level moisture to its east should support weak to moderate instability with daytime heating. Steep mid-level lapse rates should also aid updraft accelerations/intensities, with around 20-30 kt of deep-layer shear supporting modest thunderstorm organization. Isolated severe hail may occur with initially more discrete convection, but a tendency for clustering should lead to a relatively greater wind threat with time as convection spreads generally east-northeastward through the evening. Regardless, the overall severe threat from northeast CO into western NE/SD and vicinity should remain fairly isolated/marginal given the modest deep-layer shear. Low-level warm advection is forecast to increase across much of the northern/central Plains tonight as a southerly low-level jet strengthens. A surface warm front is also expected to lift northward over ND late tonight into early Monday morning. With steepening mid-level lapse rates overspreading the northern Plains in tandem with increasing low-level moisture, ample MUCAPE should be available. Most guidance shows at least isolated convection developing across parts of ND tonight in this favorable thermodynamic environment. Although deep-layer shear may remain fairly modest, it may still be sufficient for updraft organization and an isolated threat for severe hail with any elevated convection that can form. Have therefore expanded the Marginal Risk northward to account for this potential. ...Coastal Carolinas... Latest NHC forecast continues to indicate some potential for sub-tropical or tropical development of a surface low currently off the SC Coast. Regardless of development, it still appears that the more moist/tropical low-level airmass over the Gulf Stream will struggle to advance inland over coastal portions of NC/SC through the end of the Day 1 forecast period early Monday morning (16/12Z). Accordingly, tornado potential with any low-topped supercells on the north to northeast periphery of the surface low should tend to remain offshore until Day 2/Monday (after 16/12Z). Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0248 PM CDT Sun Sep 15 2024 Valid 152000Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS... ...SUMMARY... Thunderstorms capable of producing isolated severe gusts and hail may occur today and tonight across parts of the northern/central Plains. ...20z Update... Only minor adjustments were made to the D1 Convective Outlook to account for latest observational trends. See previous discussion below for more information. ..Thornton/Gleason.. 09/15/2024 .PREV DISCUSSION... /ISSUED 1128 AM CDT Sun Sep 15 2024/ ...Northern/Central Plains... An amplified upper trough along/near the West Coast this morning will further evolve into a closed upper low over northern CA and vicinity by late tonight. Ahead of this feature, modestly enhanced south-southwesterly mid-level flow will be in place over much of the western states and Rockies through the period. Although low-level moisture is expected to remain limited over much of this region, isolated strong to severe gusts may occur with any thunderstorms that can develop in a deeply mixed boundary layer favorable for gusty downdraft winds. Latest guidance continues to suggest that a relatively greater concentration of severe potential will be focused across parts of the northern/central Plains late this afternoon through tonight. Across this area, a weak surface lee trough and greater low-level moisture to its east should support weak to moderate instability with daytime heating. Steep mid-level lapse rates should also aid updraft accelerations/intensities, with around 20-30 kt of deep-layer shear supporting modest thunderstorm organization. Isolated severe hail may occur with initially more discrete convection, but a tendency for clustering should lead to a relatively greater wind threat with time as convection spreads generally east-northeastward through the evening. Regardless, the overall severe threat from northeast CO into western NE/SD and vicinity should remain fairly isolated/marginal given the modest deep-layer shear. Low-level warm advection is forecast to increase across much of the northern/central Plains tonight as a southerly low-level jet strengthens. A surface warm front is also expected to lift northward over ND late tonight into early Monday morning. With steepening mid-level lapse rates overspreading the northern Plains in tandem with increasing low-level moisture, ample MUCAPE should be available. Most guidance shows at least isolated convection developing across parts of ND tonight in this favorable thermodynamic environment. Although deep-layer shear may remain fairly modest, it may still be sufficient for updraft organization and an isolated threat for severe hail with any elevated convection that can form. Have therefore expanded the Marginal Risk northward to account for this potential. ...Coastal Carolinas... Latest NHC forecast continues to indicate some potential for sub-tropical or tropical development of a surface low currently off the SC Coast. Regardless of development, it still appears that the more moist/tropical low-level airmass over the Gulf Stream will struggle to advance inland over coastal portions of NC/SC through the end of the Day 1 forecast period early Monday morning (16/12Z). Accordingly, tornado potential with any low-topped supercells on the north to northeast periphery of the surface low should tend to remain offshore until Day 2/Monday (after 16/12Z). Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0248 PM CDT Sun Sep 15 2024 Valid 152000Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS... ...SUMMARY... Thunderstorms capable of producing isolated severe gusts and hail may occur today and tonight across parts of the northern/central Plains. ...20z Update... Only minor adjustments were made to the D1 Convective Outlook to account for latest observational trends. See previous discussion below for more information. ..Thornton/Gleason.. 09/15/2024 .PREV DISCUSSION... /ISSUED 1128 AM CDT Sun Sep 15 2024/ ...Northern/Central Plains... An amplified upper trough along/near the West Coast this morning will further evolve into a closed upper low over northern CA and vicinity by late tonight. Ahead of this feature, modestly enhanced south-southwesterly mid-level flow will be in place over much of the western states and Rockies through the period. Although low-level moisture is expected to remain limited over much of this region, isolated strong to severe gusts may occur with any thunderstorms that can develop in a deeply mixed boundary layer favorable for gusty downdraft winds. Latest guidance continues to suggest that a relatively greater concentration of severe potential will be focused across parts of the northern/central Plains late this afternoon through tonight. Across this area, a weak surface lee trough and greater low-level moisture to its east should support weak to moderate instability with daytime heating. Steep mid-level lapse rates should also aid updraft accelerations/intensities, with around 20-30 kt of deep-layer shear supporting modest thunderstorm organization. Isolated severe hail may occur with initially more discrete convection, but a tendency for clustering should lead to a relatively greater wind threat with time as convection spreads generally east-northeastward through the evening. Regardless, the overall severe threat from northeast CO into western NE/SD and vicinity should remain fairly isolated/marginal given the modest deep-layer shear. Low-level warm advection is forecast to increase across much of the northern/central Plains tonight as a southerly low-level jet strengthens. A surface warm front is also expected to lift northward over ND late tonight into early Monday morning. With steepening mid-level lapse rates overspreading the northern Plains in tandem with increasing low-level moisture, ample MUCAPE should be available. Most guidance shows at least isolated convection developing across parts of ND tonight in this favorable thermodynamic environment. Although deep-layer shear may remain fairly modest, it may still be sufficient for updraft organization and an isolated threat for severe hail with any elevated convection that can form. Have therefore expanded the Marginal Risk northward to account for this potential. ...Coastal Carolinas... Latest NHC forecast continues to indicate some potential for sub-tropical or tropical development of a surface low currently off the SC Coast. Regardless of development, it still appears that the more moist/tropical low-level airmass over the Gulf Stream will struggle to advance inland over coastal portions of NC/SC through the end of the Day 1 forecast period early Monday morning (16/12Z). Accordingly, tornado potential with any low-topped supercells on the north to northeast periphery of the surface low should tend to remain offshore until Day 2/Monday (after 16/12Z). Read more