Severe Storms

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Tue May 21 2024 Valid 221200Z - 231200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS NORTH TEXAS...SOUTHEAST OKLAHOMA...AND MUCH OF ARKANSAS TO THE MISSOURI BOOTHEEL VICINITY... ...SUMMARY... Severe thunderstorms posing a risk for damaging gusts and hail will be possible from central Texas into the Ohio Valley and lower Great Lakes vicinity on Wednesday. The highest concentration of damaging gusts and large to very large hail is expected from north Texas to the Missouri Bootheel vicinity. ...Synopsis... An upper shortwave trough will move northeast across the Upper Midwest/Great Lakes vicinity on Wednesday. Meanwhile, convectively enhanced vorticity maxima from the Day 1/Tue period will develop east/northeast across parts of the Ohio Valley/Lower Great Lakes area in broad southwesterly deep-layer flow. Further south, broad, enhanced southwesterly flow will persist over the southern Plains to the Mid-South. One or more shortwave impulses are expected to float through this area ahead of a deepening large-scale western U.S. upper trough. At the surface, an occluding low near the MN/Ontario border will lift north through the period, with a weak surface trough extending into parts of the upper Ohio Valley and lower Great Lakes. The northern extent of a surface cold front will progress eastward across the Great Lakes vicinity. Meanwhile, the front will mainly stall from IN/southern IL into central OK and northwest TX. A dryline will move east into central TX. These boundaries will become the focus for thunderstorm development during the afternoon. ...Texas to Southern IL... A moisture-rich boundary layer will be present, with dewpoints in the upper 60s to low 70s F common. Atop this moist boundary layer, steep midlevel lapse rates around 8 C/km are forecast. This will result in strong to extreme instability (2500-4000 J/kg MLCAPE). Vertical shear will be favorable for supercells, with modestly enlarged low-level hodographs become elongated/straight above 3 km. Significant hail (greater than 2 inch diameter) will be possible with initial supercell development. How long semi-discrete supercells will be maintained is a bit uncertain. Upscale development into bowing segments will likely occur, resulting in an increasing damaging wind risk with time. A 35-45 kt southwesterly low-level jet is forecast to increase by early evening. This will support increasing 0-1 km SRH (to around 200 m2/s2) and a few tornadoes will be possible. A strong tornado cannot be ruled out, especially over parts of AR into north Texas. ...IN/KY to the Lower Great Lakes... Forcing for ascent across the region will mainly be provided by any MCVs from remnant Day 1/Tue convection floating through southwesterly flow, and the eastward-advancing cold front. A moist airmass with dewpoints in mid/upper 60s will be present over IN/OH/KY, with low/mid 60s extending northeast into NY/PA and vicinity. Strong heating and a plume of steep midlevel lapse rates will support moderate destabilization during the late morning/afternoon. Vertical shear will be sufficient for organized cells, though decreasing with northeast extent into eastern NY and the Mid-Atlantic vicinity. Isolated damaging gusts and marginal hail will be possible with thunderstorms into early evening. ..Leitman.. 05/21/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Tue May 21 2024 Valid 221200Z - 231200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS NORTH TEXAS...SOUTHEAST OKLAHOMA...AND MUCH OF ARKANSAS TO THE MISSOURI BOOTHEEL VICINITY... ...SUMMARY... Severe thunderstorms posing a risk for damaging gusts and hail will be possible from central Texas into the Ohio Valley and lower Great Lakes vicinity on Wednesday. The highest concentration of damaging gusts and large to very large hail is expected from north Texas to the Missouri Bootheel vicinity. ...Synopsis... An upper shortwave trough will move northeast across the Upper Midwest/Great Lakes vicinity on Wednesday. Meanwhile, convectively enhanced vorticity maxima from the Day 1/Tue period will develop east/northeast across parts of the Ohio Valley/Lower Great Lakes area in broad southwesterly deep-layer flow. Further south, broad, enhanced southwesterly flow will persist over the southern Plains to the Mid-South. One or more shortwave impulses are expected to float through this area ahead of a deepening large-scale western U.S. upper trough. At the surface, an occluding low near the MN/Ontario border will lift north through the period, with a weak surface trough extending into parts of the upper Ohio Valley and lower Great Lakes. The northern extent of a surface cold front will progress eastward across the Great Lakes vicinity. Meanwhile, the front will mainly stall from IN/southern IL into central OK and northwest TX. A dryline will move east into central TX. These boundaries will become the focus for thunderstorm development during the afternoon. ...Texas to Southern IL... A moisture-rich boundary layer will be present, with dewpoints in the upper 60s to low 70s F common. Atop this moist boundary layer, steep midlevel lapse rates around 8 C/km are forecast. This will result in strong to extreme instability (2500-4000 J/kg MLCAPE). Vertical shear will be favorable for supercells, with modestly enlarged low-level hodographs become elongated/straight above 3 km. Significant hail (greater than 2 inch diameter) will be possible with initial supercell development. How long semi-discrete supercells will be maintained is a bit uncertain. Upscale development into bowing segments will likely occur, resulting in an increasing damaging wind risk with time. A 35-45 kt southwesterly low-level jet is forecast to increase by early evening. This will support increasing 0-1 km SRH (to around 200 m2/s2) and a few tornadoes will be possible. A strong tornado cannot be ruled out, especially over parts of AR into north Texas. ...IN/KY to the Lower Great Lakes... Forcing for ascent across the region will mainly be provided by any MCVs from remnant Day 1/Tue convection floating through southwesterly flow, and the eastward-advancing cold front. A moist airmass with dewpoints in mid/upper 60s will be present over IN/OH/KY, with low/mid 60s extending northeast into NY/PA and vicinity. Strong heating and a plume of steep midlevel lapse rates will support moderate destabilization during the late morning/afternoon. Vertical shear will be sufficient for organized cells, though decreasing with northeast extent into eastern NY and the Mid-Atlantic vicinity. Isolated damaging gusts and marginal hail will be possible with thunderstorms into early evening. ..Leitman.. 05/21/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Tue May 21 2024 Valid 221200Z - 231200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS NORTH TEXAS...SOUTHEAST OKLAHOMA...AND MUCH OF ARKANSAS TO THE MISSOURI BOOTHEEL VICINITY... ...SUMMARY... Severe thunderstorms posing a risk for damaging gusts and hail will be possible from central Texas into the Ohio Valley and lower Great Lakes vicinity on Wednesday. The highest concentration of damaging gusts and large to very large hail is expected from north Texas to the Missouri Bootheel vicinity. ...Synopsis... An upper shortwave trough will move northeast across the Upper Midwest/Great Lakes vicinity on Wednesday. Meanwhile, convectively enhanced vorticity maxima from the Day 1/Tue period will develop east/northeast across parts of the Ohio Valley/Lower Great Lakes area in broad southwesterly deep-layer flow. Further south, broad, enhanced southwesterly flow will persist over the southern Plains to the Mid-South. One or more shortwave impulses are expected to float through this area ahead of a deepening large-scale western U.S. upper trough. At the surface, an occluding low near the MN/Ontario border will lift north through the period, with a weak surface trough extending into parts of the upper Ohio Valley and lower Great Lakes. The northern extent of a surface cold front will progress eastward across the Great Lakes vicinity. Meanwhile, the front will mainly stall from IN/southern IL into central OK and northwest TX. A dryline will move east into central TX. These boundaries will become the focus for thunderstorm development during the afternoon. ...Texas to Southern IL... A moisture-rich boundary layer will be present, with dewpoints in the upper 60s to low 70s F common. Atop this moist boundary layer, steep midlevel lapse rates around 8 C/km are forecast. This will result in strong to extreme instability (2500-4000 J/kg MLCAPE). Vertical shear will be favorable for supercells, with modestly enlarged low-level hodographs become elongated/straight above 3 km. Significant hail (greater than 2 inch diameter) will be possible with initial supercell development. How long semi-discrete supercells will be maintained is a bit uncertain. Upscale development into bowing segments will likely occur, resulting in an increasing damaging wind risk with time. A 35-45 kt southwesterly low-level jet is forecast to increase by early evening. This will support increasing 0-1 km SRH (to around 200 m2/s2) and a few tornadoes will be possible. A strong tornado cannot be ruled out, especially over parts of AR into north Texas. ...IN/KY to the Lower Great Lakes... Forcing for ascent across the region will mainly be provided by any MCVs from remnant Day 1/Tue convection floating through southwesterly flow, and the eastward-advancing cold front. A moist airmass with dewpoints in mid/upper 60s will be present over IN/OH/KY, with low/mid 60s extending northeast into NY/PA and vicinity. Strong heating and a plume of steep midlevel lapse rates will support moderate destabilization during the late morning/afternoon. Vertical shear will be sufficient for organized cells, though decreasing with northeast extent into eastern NY and the Mid-Atlantic vicinity. Isolated damaging gusts and marginal hail will be possible with thunderstorms into early evening. ..Leitman.. 05/21/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1254 AM CDT Tue May 21 2024 Valid 211200Z - 221200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS IN PARTS OF IOWA...NORTHERN MISSOURI...NORTHWEST ILLINOIS...SOUTHWEST WISCONSIN...AND FAR SOUTHEAST MINNESOTA... ...SUMMARY... An outbreak of severe thunderstorms, including the potential for strong tornadoes, is probable today, peaking in the afternoon to early evening. The area most likely to be impacted will include the Mid to Lower Missouri Valley across the Mid to Upper Mississippi Valley to the Lake Michigan vicinity. ...Mid-Lower MO Valley into the western Great Lakes... An MCS and other remnant storm clusters are expected to be ongoing across parts of the Mid-MO Valley to Upper MS Valley at 12Z. How exactly this morning activity evolves eastward is somewhat uncertain. An initial bout of severe wind and hail may persist with this activity through midday. This will likely be over a focused mesoscale corridor, given a stout elevated mixed layer to its south and progressively limited instability to the north. Quick air mass recovery is expected in the wake of this early-day convection within a progressive/highly dynamic synoptic pattern. Pronounced surface cyclogenesis is expected with amplification of a vigorous shortwave trough from the central High Plains to the Upper MS Valley. This will yield substantial amplification of low to mid-level flow, with a belt of 70+ kt 500-mb winds extending from eastern KS and western MO through at least IA this afternoon. As the surface cyclone deepens, an attendant cold front will surge eastward into central IA through northwest MO by 00Z. Very steep mid-level lapse rates will overspread the increasingly moist warm sector, supporting aggressive diurnal destabilization especially on the southern fringe of lingering convection/cloud cover. Initial supercell development should occur near the deepening surface cyclone by midday to early afternoon over the Mid-MO Valley. Increasingly widespread thunderstorm development is expected through the afternoon from the Upper MS Valley southward to the Lower MO Valley. Deep-layer shear will support an initial mixed mode of semi-discrete supercells and embedded supercells in clusters. But by late afternoon, upscale growth into a fast-moving arc of bowing line segments and embedded supercells is expected. Additional supercells should also form downstream along the effective warm front/remnant large-scale outflow that advances north in southern to central WI. Very large hail potential will be most likely with the initial supercell development, and with southern extent where semi-discrete storms should persist longest. Tornadoes, some of which should be strong, appear most probable from northern MO northward into southeast MN and southwest to central WI from both supercell and mesovortex processes. How far north strong-tornado potential can be realized will be modulated by the degree of destabilization in the wake of the early-day convection, but low-level SRH will be quite large. Damaging winds will become increasingly likely later in the afternoon into the evening with gusts of 75-90 mph possible as a well-organized QLCS forms. This should tend to be maximized across parts of central/eastern IA into western IL and northern MO. QLCS intensity should subside after dusk, as convection outpaces larger buoyancy, but a damaging wind threat could persist into Lower MI through the Mid-MO Valley. ...Ozarks to central TX... Convective coverage will decrease with southward extent as large-scale ascent focuses northward toward the Upper MS Valley and western Great Lakes. Nevertheless, scattered severe storms are possible during the late afternoon/evening near where the cold front overtakes the dryline in the Ozarks. More isolated convective coverage is expected southwestward along the dryline in central TX. Large buoyancy and ample deep-layer shear will support a primary threat of very large hail in TX. While a mix of large hail, damaging winds, and a few tornadoes will be possible over the Ozarks. ...New England and northeast NY... A low-amplitude shortwave impulse/remnant MCV will move across southern QC and northern New England. This will result in a band of enhanced westerly deep-layer flow from northern NY into ME. A seasonally moist airmass will be in place with surface dewpoints into the low 60s F, with strong heating and steepening low-level lapse rates. Modest MLCAPE and effective shear from 30-35 kt will support a few organized cells. Moderately elongated hodographs suggest marginally severe hail will be possible along with locally damaging wind gusts. ..Grams/Barnes.. 05/21/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1254 AM CDT Tue May 21 2024 Valid 211200Z - 221200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS IN PARTS OF IOWA...NORTHERN MISSOURI...NORTHWEST ILLINOIS...SOUTHWEST WISCONSIN...AND FAR SOUTHEAST MINNESOTA... ...SUMMARY... An outbreak of severe thunderstorms, including the potential for strong tornadoes, is probable today, peaking in the afternoon to early evening. The area most likely to be impacted will include the Mid to Lower Missouri Valley across the Mid to Upper Mississippi Valley to the Lake Michigan vicinity. ...Mid-Lower MO Valley into the western Great Lakes... An MCS and other remnant storm clusters are expected to be ongoing across parts of the Mid-MO Valley to Upper MS Valley at 12Z. How exactly this morning activity evolves eastward is somewhat uncertain. An initial bout of severe wind and hail may persist with this activity through midday. This will likely be over a focused mesoscale corridor, given a stout elevated mixed layer to its south and progressively limited instability to the north. Quick air mass recovery is expected in the wake of this early-day convection within a progressive/highly dynamic synoptic pattern. Pronounced surface cyclogenesis is expected with amplification of a vigorous shortwave trough from the central High Plains to the Upper MS Valley. This will yield substantial amplification of low to mid-level flow, with a belt of 70+ kt 500-mb winds extending from eastern KS and western MO through at least IA this afternoon. As the surface cyclone deepens, an attendant cold front will surge eastward into central IA through northwest MO by 00Z. Very steep mid-level lapse rates will overspread the increasingly moist warm sector, supporting aggressive diurnal destabilization especially on the southern fringe of lingering convection/cloud cover. Initial supercell development should occur near the deepening surface cyclone by midday to early afternoon over the Mid-MO Valley. Increasingly widespread thunderstorm development is expected through the afternoon from the Upper MS Valley southward to the Lower MO Valley. Deep-layer shear will support an initial mixed mode of semi-discrete supercells and embedded supercells in clusters. But by late afternoon, upscale growth into a fast-moving arc of bowing line segments and embedded supercells is expected. Additional supercells should also form downstream along the effective warm front/remnant large-scale outflow that advances north in southern to central WI. Very large hail potential will be most likely with the initial supercell development, and with southern extent where semi-discrete storms should persist longest. Tornadoes, some of which should be strong, appear most probable from northern MO northward into southeast MN and southwest to central WI from both supercell and mesovortex processes. How far north strong-tornado potential can be realized will be modulated by the degree of destabilization in the wake of the early-day convection, but low-level SRH will be quite large. Damaging winds will become increasingly likely later in the afternoon into the evening with gusts of 75-90 mph possible as a well-organized QLCS forms. This should tend to be maximized across parts of central/eastern IA into western IL and northern MO. QLCS intensity should subside after dusk, as convection outpaces larger buoyancy, but a damaging wind threat could persist into Lower MI through the Mid-MO Valley. ...Ozarks to central TX... Convective coverage will decrease with southward extent as large-scale ascent focuses northward toward the Upper MS Valley and western Great Lakes. Nevertheless, scattered severe storms are possible during the late afternoon/evening near where the cold front overtakes the dryline in the Ozarks. More isolated convective coverage is expected southwestward along the dryline in central TX. Large buoyancy and ample deep-layer shear will support a primary threat of very large hail in TX. While a mix of large hail, damaging winds, and a few tornadoes will be possible over the Ozarks. ...New England and northeast NY... A low-amplitude shortwave impulse/remnant MCV will move across southern QC and northern New England. This will result in a band of enhanced westerly deep-layer flow from northern NY into ME. A seasonally moist airmass will be in place with surface dewpoints into the low 60s F, with strong heating and steepening low-level lapse rates. Modest MLCAPE and effective shear from 30-35 kt will support a few organized cells. Moderately elongated hodographs suggest marginally severe hail will be possible along with locally damaging wind gusts. ..Grams/Barnes.. 05/21/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1254 AM CDT Tue May 21 2024 Valid 211200Z - 221200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS IN PARTS OF IOWA...NORTHERN MISSOURI...NORTHWEST ILLINOIS...SOUTHWEST WISCONSIN...AND FAR SOUTHEAST MINNESOTA... ...SUMMARY... An outbreak of severe thunderstorms, including the potential for strong tornadoes, is probable today, peaking in the afternoon to early evening. The area most likely to be impacted will include the Mid to Lower Missouri Valley across the Mid to Upper Mississippi Valley to the Lake Michigan vicinity. ...Mid-Lower MO Valley into the western Great Lakes... An MCS and other remnant storm clusters are expected to be ongoing across parts of the Mid-MO Valley to Upper MS Valley at 12Z. How exactly this morning activity evolves eastward is somewhat uncertain. An initial bout of severe wind and hail may persist with this activity through midday. This will likely be over a focused mesoscale corridor, given a stout elevated mixed layer to its south and progressively limited instability to the north. Quick air mass recovery is expected in the wake of this early-day convection within a progressive/highly dynamic synoptic pattern. Pronounced surface cyclogenesis is expected with amplification of a vigorous shortwave trough from the central High Plains to the Upper MS Valley. This will yield substantial amplification of low to mid-level flow, with a belt of 70+ kt 500-mb winds extending from eastern KS and western MO through at least IA this afternoon. As the surface cyclone deepens, an attendant cold front will surge eastward into central IA through northwest MO by 00Z. Very steep mid-level lapse rates will overspread the increasingly moist warm sector, supporting aggressive diurnal destabilization especially on the southern fringe of lingering convection/cloud cover. Initial supercell development should occur near the deepening surface cyclone by midday to early afternoon over the Mid-MO Valley. Increasingly widespread thunderstorm development is expected through the afternoon from the Upper MS Valley southward to the Lower MO Valley. Deep-layer shear will support an initial mixed mode of semi-discrete supercells and embedded supercells in clusters. But by late afternoon, upscale growth into a fast-moving arc of bowing line segments and embedded supercells is expected. Additional supercells should also form downstream along the effective warm front/remnant large-scale outflow that advances north in southern to central WI. Very large hail potential will be most likely with the initial supercell development, and with southern extent where semi-discrete storms should persist longest. Tornadoes, some of which should be strong, appear most probable from northern MO northward into southeast MN and southwest to central WI from both supercell and mesovortex processes. How far north strong-tornado potential can be realized will be modulated by the degree of destabilization in the wake of the early-day convection, but low-level SRH will be quite large. Damaging winds will become increasingly likely later in the afternoon into the evening with gusts of 75-90 mph possible as a well-organized QLCS forms. This should tend to be maximized across parts of central/eastern IA into western IL and northern MO. QLCS intensity should subside after dusk, as convection outpaces larger buoyancy, but a damaging wind threat could persist into Lower MI through the Mid-MO Valley. ...Ozarks to central TX... Convective coverage will decrease with southward extent as large-scale ascent focuses northward toward the Upper MS Valley and western Great Lakes. Nevertheless, scattered severe storms are possible during the late afternoon/evening near where the cold front overtakes the dryline in the Ozarks. More isolated convective coverage is expected southwestward along the dryline in central TX. Large buoyancy and ample deep-layer shear will support a primary threat of very large hail in TX. While a mix of large hail, damaging winds, and a few tornadoes will be possible over the Ozarks. ...New England and northeast NY... A low-amplitude shortwave impulse/remnant MCV will move across southern QC and northern New England. This will result in a band of enhanced westerly deep-layer flow from northern NY into ME. A seasonally moist airmass will be in place with surface dewpoints into the low 60s F, with strong heating and steepening low-level lapse rates. Modest MLCAPE and effective shear from 30-35 kt will support a few organized cells. Moderately elongated hodographs suggest marginally severe hail will be possible along with locally damaging wind gusts. ..Grams/Barnes.. 05/21/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1254 AM CDT Tue May 21 2024 Valid 211200Z - 221200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS IN PARTS OF IOWA...NORTHERN MISSOURI...NORTHWEST ILLINOIS...SOUTHWEST WISCONSIN...AND FAR SOUTHEAST MINNESOTA... ...SUMMARY... An outbreak of severe thunderstorms, including the potential for strong tornadoes, is probable today, peaking in the afternoon to early evening. The area most likely to be impacted will include the Mid to Lower Missouri Valley across the Mid to Upper Mississippi Valley to the Lake Michigan vicinity. ...Mid-Lower MO Valley into the western Great Lakes... An MCS and other remnant storm clusters are expected to be ongoing across parts of the Mid-MO Valley to Upper MS Valley at 12Z. How exactly this morning activity evolves eastward is somewhat uncertain. An initial bout of severe wind and hail may persist with this activity through midday. This will likely be over a focused mesoscale corridor, given a stout elevated mixed layer to its south and progressively limited instability to the north. Quick air mass recovery is expected in the wake of this early-day convection within a progressive/highly dynamic synoptic pattern. Pronounced surface cyclogenesis is expected with amplification of a vigorous shortwave trough from the central High Plains to the Upper MS Valley. This will yield substantial amplification of low to mid-level flow, with a belt of 70+ kt 500-mb winds extending from eastern KS and western MO through at least IA this afternoon. As the surface cyclone deepens, an attendant cold front will surge eastward into central IA through northwest MO by 00Z. Very steep mid-level lapse rates will overspread the increasingly moist warm sector, supporting aggressive diurnal destabilization especially on the southern fringe of lingering convection/cloud cover. Initial supercell development should occur near the deepening surface cyclone by midday to early afternoon over the Mid-MO Valley. Increasingly widespread thunderstorm development is expected through the afternoon from the Upper MS Valley southward to the Lower MO Valley. Deep-layer shear will support an initial mixed mode of semi-discrete supercells and embedded supercells in clusters. But by late afternoon, upscale growth into a fast-moving arc of bowing line segments and embedded supercells is expected. Additional supercells should also form downstream along the effective warm front/remnant large-scale outflow that advances north in southern to central WI. Very large hail potential will be most likely with the initial supercell development, and with southern extent where semi-discrete storms should persist longest. Tornadoes, some of which should be strong, appear most probable from northern MO northward into southeast MN and southwest to central WI from both supercell and mesovortex processes. How far north strong-tornado potential can be realized will be modulated by the degree of destabilization in the wake of the early-day convection, but low-level SRH will be quite large. Damaging winds will become increasingly likely later in the afternoon into the evening with gusts of 75-90 mph possible as a well-organized QLCS forms. This should tend to be maximized across parts of central/eastern IA into western IL and northern MO. QLCS intensity should subside after dusk, as convection outpaces larger buoyancy, but a damaging wind threat could persist into Lower MI through the Mid-MO Valley. ...Ozarks to central TX... Convective coverage will decrease with southward extent as large-scale ascent focuses northward toward the Upper MS Valley and western Great Lakes. Nevertheless, scattered severe storms are possible during the late afternoon/evening near where the cold front overtakes the dryline in the Ozarks. More isolated convective coverage is expected southwestward along the dryline in central TX. Large buoyancy and ample deep-layer shear will support a primary threat of very large hail in TX. While a mix of large hail, damaging winds, and a few tornadoes will be possible over the Ozarks. ...New England and northeast NY... A low-amplitude shortwave impulse/remnant MCV will move across southern QC and northern New England. This will result in a band of enhanced westerly deep-layer flow from northern NY into ME. A seasonally moist airmass will be in place with surface dewpoints into the low 60s F, with strong heating and steepening low-level lapse rates. Modest MLCAPE and effective shear from 30-35 kt will support a few organized cells. Moderately elongated hodographs suggest marginally severe hail will be possible along with locally damaging wind gusts. ..Grams/Barnes.. 05/21/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1254 AM CDT Tue May 21 2024 Valid 211200Z - 221200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS IN PARTS OF IOWA...NORTHERN MISSOURI...NORTHWEST ILLINOIS...SOUTHWEST WISCONSIN...AND FAR SOUTHEAST MINNESOTA... ...SUMMARY... An outbreak of severe thunderstorms, including the potential for strong tornadoes, is probable today, peaking in the afternoon to early evening. The area most likely to be impacted will include the Mid to Lower Missouri Valley across the Mid to Upper Mississippi Valley to the Lake Michigan vicinity. ...Mid-Lower MO Valley into the western Great Lakes... An MCS and other remnant storm clusters are expected to be ongoing across parts of the Mid-MO Valley to Upper MS Valley at 12Z. How exactly this morning activity evolves eastward is somewhat uncertain. An initial bout of severe wind and hail may persist with this activity through midday. This will likely be over a focused mesoscale corridor, given a stout elevated mixed layer to its south and progressively limited instability to the north. Quick air mass recovery is expected in the wake of this early-day convection within a progressive/highly dynamic synoptic pattern. Pronounced surface cyclogenesis is expected with amplification of a vigorous shortwave trough from the central High Plains to the Upper MS Valley. This will yield substantial amplification of low to mid-level flow, with a belt of 70+ kt 500-mb winds extending from eastern KS and western MO through at least IA this afternoon. As the surface cyclone deepens, an attendant cold front will surge eastward into central IA through northwest MO by 00Z. Very steep mid-level lapse rates will overspread the increasingly moist warm sector, supporting aggressive diurnal destabilization especially on the southern fringe of lingering convection/cloud cover. Initial supercell development should occur near the deepening surface cyclone by midday to early afternoon over the Mid-MO Valley. Increasingly widespread thunderstorm development is expected through the afternoon from the Upper MS Valley southward to the Lower MO Valley. Deep-layer shear will support an initial mixed mode of semi-discrete supercells and embedded supercells in clusters. But by late afternoon, upscale growth into a fast-moving arc of bowing line segments and embedded supercells is expected. Additional supercells should also form downstream along the effective warm front/remnant large-scale outflow that advances north in southern to central WI. Very large hail potential will be most likely with the initial supercell development, and with southern extent where semi-discrete storms should persist longest. Tornadoes, some of which should be strong, appear most probable from northern MO northward into southeast MN and southwest to central WI from both supercell and mesovortex processes. How far north strong-tornado potential can be realized will be modulated by the degree of destabilization in the wake of the early-day convection, but low-level SRH will be quite large. Damaging winds will become increasingly likely later in the afternoon into the evening with gusts of 75-90 mph possible as a well-organized QLCS forms. This should tend to be maximized across parts of central/eastern IA into western IL and northern MO. QLCS intensity should subside after dusk, as convection outpaces larger buoyancy, but a damaging wind threat could persist into Lower MI through the Mid-MO Valley. ...Ozarks to central TX... Convective coverage will decrease with southward extent as large-scale ascent focuses northward toward the Upper MS Valley and western Great Lakes. Nevertheless, scattered severe storms are possible during the late afternoon/evening near where the cold front overtakes the dryline in the Ozarks. More isolated convective coverage is expected southwestward along the dryline in central TX. Large buoyancy and ample deep-layer shear will support a primary threat of very large hail in TX. While a mix of large hail, damaging winds, and a few tornadoes will be possible over the Ozarks. ...New England and northeast NY... A low-amplitude shortwave impulse/remnant MCV will move across southern QC and northern New England. This will result in a band of enhanced westerly deep-layer flow from northern NY into ME. A seasonally moist airmass will be in place with surface dewpoints into the low 60s F, with strong heating and steepening low-level lapse rates. Modest MLCAPE and effective shear from 30-35 kt will support a few organized cells. Moderately elongated hodographs suggest marginally severe hail will be possible along with locally damaging wind gusts. ..Grams/Barnes.. 05/21/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1254 AM CDT Tue May 21 2024 Valid 211200Z - 221200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS IN PARTS OF IOWA...NORTHERN MISSOURI...NORTHWEST ILLINOIS...SOUTHWEST WISCONSIN...AND FAR SOUTHEAST MINNESOTA... ...SUMMARY... An outbreak of severe thunderstorms, including the potential for strong tornadoes, is probable today, peaking in the afternoon to early evening. The area most likely to be impacted will include the Mid to Lower Missouri Valley across the Mid to Upper Mississippi Valley to the Lake Michigan vicinity. ...Mid-Lower MO Valley into the western Great Lakes... An MCS and other remnant storm clusters are expected to be ongoing across parts of the Mid-MO Valley to Upper MS Valley at 12Z. How exactly this morning activity evolves eastward is somewhat uncertain. An initial bout of severe wind and hail may persist with this activity through midday. This will likely be over a focused mesoscale corridor, given a stout elevated mixed layer to its south and progressively limited instability to the north. Quick air mass recovery is expected in the wake of this early-day convection within a progressive/highly dynamic synoptic pattern. Pronounced surface cyclogenesis is expected with amplification of a vigorous shortwave trough from the central High Plains to the Upper MS Valley. This will yield substantial amplification of low to mid-level flow, with a belt of 70+ kt 500-mb winds extending from eastern KS and western MO through at least IA this afternoon. As the surface cyclone deepens, an attendant cold front will surge eastward into central IA through northwest MO by 00Z. Very steep mid-level lapse rates will overspread the increasingly moist warm sector, supporting aggressive diurnal destabilization especially on the southern fringe of lingering convection/cloud cover. Initial supercell development should occur near the deepening surface cyclone by midday to early afternoon over the Mid-MO Valley. Increasingly widespread thunderstorm development is expected through the afternoon from the Upper MS Valley southward to the Lower MO Valley. Deep-layer shear will support an initial mixed mode of semi-discrete supercells and embedded supercells in clusters. But by late afternoon, upscale growth into a fast-moving arc of bowing line segments and embedded supercells is expected. Additional supercells should also form downstream along the effective warm front/remnant large-scale outflow that advances north in southern to central WI. Very large hail potential will be most likely with the initial supercell development, and with southern extent where semi-discrete storms should persist longest. Tornadoes, some of which should be strong, appear most probable from northern MO northward into southeast MN and southwest to central WI from both supercell and mesovortex processes. How far north strong-tornado potential can be realized will be modulated by the degree of destabilization in the wake of the early-day convection, but low-level SRH will be quite large. Damaging winds will become increasingly likely later in the afternoon into the evening with gusts of 75-90 mph possible as a well-organized QLCS forms. This should tend to be maximized across parts of central/eastern IA into western IL and northern MO. QLCS intensity should subside after dusk, as convection outpaces larger buoyancy, but a damaging wind threat could persist into Lower MI through the Mid-MO Valley. ...Ozarks to central TX... Convective coverage will decrease with southward extent as large-scale ascent focuses northward toward the Upper MS Valley and western Great Lakes. Nevertheless, scattered severe storms are possible during the late afternoon/evening near where the cold front overtakes the dryline in the Ozarks. More isolated convective coverage is expected southwestward along the dryline in central TX. Large buoyancy and ample deep-layer shear will support a primary threat of very large hail in TX. While a mix of large hail, damaging winds, and a few tornadoes will be possible over the Ozarks. ...New England and northeast NY... A low-amplitude shortwave impulse/remnant MCV will move across southern QC and northern New England. This will result in a band of enhanced westerly deep-layer flow from northern NY into ME. A seasonally moist airmass will be in place with surface dewpoints into the low 60s F, with strong heating and steepening low-level lapse rates. Modest MLCAPE and effective shear from 30-35 kt will support a few organized cells. Moderately elongated hodographs suggest marginally severe hail will be possible along with locally damaging wind gusts. ..Grams/Barnes.. 05/21/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1254 AM CDT Tue May 21 2024 Valid 211200Z - 221200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS IN PARTS OF IOWA...NORTHERN MISSOURI...NORTHWEST ILLINOIS...SOUTHWEST WISCONSIN...AND FAR SOUTHEAST MINNESOTA... ...SUMMARY... An outbreak of severe thunderstorms, including the potential for strong tornadoes, is probable today, peaking in the afternoon to early evening. The area most likely to be impacted will include the Mid to Lower Missouri Valley across the Mid to Upper Mississippi Valley to the Lake Michigan vicinity. ...Mid-Lower MO Valley into the western Great Lakes... An MCS and other remnant storm clusters are expected to be ongoing across parts of the Mid-MO Valley to Upper MS Valley at 12Z. How exactly this morning activity evolves eastward is somewhat uncertain. An initial bout of severe wind and hail may persist with this activity through midday. This will likely be over a focused mesoscale corridor, given a stout elevated mixed layer to its south and progressively limited instability to the north. Quick air mass recovery is expected in the wake of this early-day convection within a progressive/highly dynamic synoptic pattern. Pronounced surface cyclogenesis is expected with amplification of a vigorous shortwave trough from the central High Plains to the Upper MS Valley. This will yield substantial amplification of low to mid-level flow, with a belt of 70+ kt 500-mb winds extending from eastern KS and western MO through at least IA this afternoon. As the surface cyclone deepens, an attendant cold front will surge eastward into central IA through northwest MO by 00Z. Very steep mid-level lapse rates will overspread the increasingly moist warm sector, supporting aggressive diurnal destabilization especially on the southern fringe of lingering convection/cloud cover. Initial supercell development should occur near the deepening surface cyclone by midday to early afternoon over the Mid-MO Valley. Increasingly widespread thunderstorm development is expected through the afternoon from the Upper MS Valley southward to the Lower MO Valley. Deep-layer shear will support an initial mixed mode of semi-discrete supercells and embedded supercells in clusters. But by late afternoon, upscale growth into a fast-moving arc of bowing line segments and embedded supercells is expected. Additional supercells should also form downstream along the effective warm front/remnant large-scale outflow that advances north in southern to central WI. Very large hail potential will be most likely with the initial supercell development, and with southern extent where semi-discrete storms should persist longest. Tornadoes, some of which should be strong, appear most probable from northern MO northward into southeast MN and southwest to central WI from both supercell and mesovortex processes. How far north strong-tornado potential can be realized will be modulated by the degree of destabilization in the wake of the early-day convection, but low-level SRH will be quite large. Damaging winds will become increasingly likely later in the afternoon into the evening with gusts of 75-90 mph possible as a well-organized QLCS forms. This should tend to be maximized across parts of central/eastern IA into western IL and northern MO. QLCS intensity should subside after dusk, as convection outpaces larger buoyancy, but a damaging wind threat could persist into Lower MI through the Mid-MO Valley. ...Ozarks to central TX... Convective coverage will decrease with southward extent as large-scale ascent focuses northward toward the Upper MS Valley and western Great Lakes. Nevertheless, scattered severe storms are possible during the late afternoon/evening near where the cold front overtakes the dryline in the Ozarks. More isolated convective coverage is expected southwestward along the dryline in central TX. Large buoyancy and ample deep-layer shear will support a primary threat of very large hail in TX. While a mix of large hail, damaging winds, and a few tornadoes will be possible over the Ozarks. ...New England and northeast NY... A low-amplitude shortwave impulse/remnant MCV will move across southern QC and northern New England. This will result in a band of enhanced westerly deep-layer flow from northern NY into ME. A seasonally moist airmass will be in place with surface dewpoints into the low 60s F, with strong heating and steepening low-level lapse rates. Modest MLCAPE and effective shear from 30-35 kt will support a few organized cells. Moderately elongated hodographs suggest marginally severe hail will be possible along with locally damaging wind gusts. ..Grams/Barnes.. 05/21/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1254 AM CDT Tue May 21 2024 Valid 211200Z - 221200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS IN PARTS OF IOWA...NORTHERN MISSOURI...NORTHWEST ILLINOIS...SOUTHWEST WISCONSIN...AND FAR SOUTHEAST MINNESOTA... ...SUMMARY... An outbreak of severe thunderstorms, including the potential for strong tornadoes, is probable today, peaking in the afternoon to early evening. The area most likely to be impacted will include the Mid to Lower Missouri Valley across the Mid to Upper Mississippi Valley to the Lake Michigan vicinity. ...Mid-Lower MO Valley into the western Great Lakes... An MCS and other remnant storm clusters are expected to be ongoing across parts of the Mid-MO Valley to Upper MS Valley at 12Z. How exactly this morning activity evolves eastward is somewhat uncertain. An initial bout of severe wind and hail may persist with this activity through midday. This will likely be over a focused mesoscale corridor, given a stout elevated mixed layer to its south and progressively limited instability to the north. Quick air mass recovery is expected in the wake of this early-day convection within a progressive/highly dynamic synoptic pattern. Pronounced surface cyclogenesis is expected with amplification of a vigorous shortwave trough from the central High Plains to the Upper MS Valley. This will yield substantial amplification of low to mid-level flow, with a belt of 70+ kt 500-mb winds extending from eastern KS and western MO through at least IA this afternoon. As the surface cyclone deepens, an attendant cold front will surge eastward into central IA through northwest MO by 00Z. Very steep mid-level lapse rates will overspread the increasingly moist warm sector, supporting aggressive diurnal destabilization especially on the southern fringe of lingering convection/cloud cover. Initial supercell development should occur near the deepening surface cyclone by midday to early afternoon over the Mid-MO Valley. Increasingly widespread thunderstorm development is expected through the afternoon from the Upper MS Valley southward to the Lower MO Valley. Deep-layer shear will support an initial mixed mode of semi-discrete supercells and embedded supercells in clusters. But by late afternoon, upscale growth into a fast-moving arc of bowing line segments and embedded supercells is expected. Additional supercells should also form downstream along the effective warm front/remnant large-scale outflow that advances north in southern to central WI. Very large hail potential will be most likely with the initial supercell development, and with southern extent where semi-discrete storms should persist longest. Tornadoes, some of which should be strong, appear most probable from northern MO northward into southeast MN and southwest to central WI from both supercell and mesovortex processes. How far north strong-tornado potential can be realized will be modulated by the degree of destabilization in the wake of the early-day convection, but low-level SRH will be quite large. Damaging winds will become increasingly likely later in the afternoon into the evening with gusts of 75-90 mph possible as a well-organized QLCS forms. This should tend to be maximized across parts of central/eastern IA into western IL and northern MO. QLCS intensity should subside after dusk, as convection outpaces larger buoyancy, but a damaging wind threat could persist into Lower MI through the Mid-MO Valley. ...Ozarks to central TX... Convective coverage will decrease with southward extent as large-scale ascent focuses northward toward the Upper MS Valley and western Great Lakes. Nevertheless, scattered severe storms are possible during the late afternoon/evening near where the cold front overtakes the dryline in the Ozarks. More isolated convective coverage is expected southwestward along the dryline in central TX. Large buoyancy and ample deep-layer shear will support a primary threat of very large hail in TX. While a mix of large hail, damaging winds, and a few tornadoes will be possible over the Ozarks. ...New England and northeast NY... A low-amplitude shortwave impulse/remnant MCV will move across southern QC and northern New England. This will result in a band of enhanced westerly deep-layer flow from northern NY into ME. A seasonally moist airmass will be in place with surface dewpoints into the low 60s F, with strong heating and steepening low-level lapse rates. Modest MLCAPE and effective shear from 30-35 kt will support a few organized cells. Moderately elongated hodographs suggest marginally severe hail will be possible along with locally damaging wind gusts. ..Grams/Barnes.. 05/21/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1254 AM CDT Tue May 21 2024 Valid 211200Z - 221200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS IN PARTS OF IOWA...NORTHERN MISSOURI...NORTHWEST ILLINOIS...SOUTHWEST WISCONSIN...AND FAR SOUTHEAST MINNESOTA... ...SUMMARY... An outbreak of severe thunderstorms, including the potential for strong tornadoes, is probable today, peaking in the afternoon to early evening. The area most likely to be impacted will include the Mid to Lower Missouri Valley across the Mid to Upper Mississippi Valley to the Lake Michigan vicinity. ...Mid-Lower MO Valley into the western Great Lakes... An MCS and other remnant storm clusters are expected to be ongoing across parts of the Mid-MO Valley to Upper MS Valley at 12Z. How exactly this morning activity evolves eastward is somewhat uncertain. An initial bout of severe wind and hail may persist with this activity through midday. This will likely be over a focused mesoscale corridor, given a stout elevated mixed layer to its south and progressively limited instability to the north. Quick air mass recovery is expected in the wake of this early-day convection within a progressive/highly dynamic synoptic pattern. Pronounced surface cyclogenesis is expected with amplification of a vigorous shortwave trough from the central High Plains to the Upper MS Valley. This will yield substantial amplification of low to mid-level flow, with a belt of 70+ kt 500-mb winds extending from eastern KS and western MO through at least IA this afternoon. As the surface cyclone deepens, an attendant cold front will surge eastward into central IA through northwest MO by 00Z. Very steep mid-level lapse rates will overspread the increasingly moist warm sector, supporting aggressive diurnal destabilization especially on the southern fringe of lingering convection/cloud cover. Initial supercell development should occur near the deepening surface cyclone by midday to early afternoon over the Mid-MO Valley. Increasingly widespread thunderstorm development is expected through the afternoon from the Upper MS Valley southward to the Lower MO Valley. Deep-layer shear will support an initial mixed mode of semi-discrete supercells and embedded supercells in clusters. But by late afternoon, upscale growth into a fast-moving arc of bowing line segments and embedded supercells is expected. Additional supercells should also form downstream along the effective warm front/remnant large-scale outflow that advances north in southern to central WI. Very large hail potential will be most likely with the initial supercell development, and with southern extent where semi-discrete storms should persist longest. Tornadoes, some of which should be strong, appear most probable from northern MO northward into southeast MN and southwest to central WI from both supercell and mesovortex processes. How far north strong-tornado potential can be realized will be modulated by the degree of destabilization in the wake of the early-day convection, but low-level SRH will be quite large. Damaging winds will become increasingly likely later in the afternoon into the evening with gusts of 75-90 mph possible as a well-organized QLCS forms. This should tend to be maximized across parts of central/eastern IA into western IL and northern MO. QLCS intensity should subside after dusk, as convection outpaces larger buoyancy, but a damaging wind threat could persist into Lower MI through the Mid-MO Valley. ...Ozarks to central TX... Convective coverage will decrease with southward extent as large-scale ascent focuses northward toward the Upper MS Valley and western Great Lakes. Nevertheless, scattered severe storms are possible during the late afternoon/evening near where the cold front overtakes the dryline in the Ozarks. More isolated convective coverage is expected southwestward along the dryline in central TX. Large buoyancy and ample deep-layer shear will support a primary threat of very large hail in TX. While a mix of large hail, damaging winds, and a few tornadoes will be possible over the Ozarks. ...New England and northeast NY... A low-amplitude shortwave impulse/remnant MCV will move across southern QC and northern New England. This will result in a band of enhanced westerly deep-layer flow from northern NY into ME. A seasonally moist airmass will be in place with surface dewpoints into the low 60s F, with strong heating and steepening low-level lapse rates. Modest MLCAPE and effective shear from 30-35 kt will support a few organized cells. Moderately elongated hodographs suggest marginally severe hail will be possible along with locally damaging wind gusts. ..Grams/Barnes.. 05/21/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1254 AM CDT Tue May 21 2024 Valid 211200Z - 221200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS IN PARTS OF IOWA...NORTHERN MISSOURI...NORTHWEST ILLINOIS...SOUTHWEST WISCONSIN...AND FAR SOUTHEAST MINNESOTA... ...SUMMARY... An outbreak of severe thunderstorms, including the potential for strong tornadoes, is probable today, peaking in the afternoon to early evening. The area most likely to be impacted will include the Mid to Lower Missouri Valley across the Mid to Upper Mississippi Valley to the Lake Michigan vicinity. ...Mid-Lower MO Valley into the western Great Lakes... An MCS and other remnant storm clusters are expected to be ongoing across parts of the Mid-MO Valley to Upper MS Valley at 12Z. How exactly this morning activity evolves eastward is somewhat uncertain. An initial bout of severe wind and hail may persist with this activity through midday. This will likely be over a focused mesoscale corridor, given a stout elevated mixed layer to its south and progressively limited instability to the north. Quick air mass recovery is expected in the wake of this early-day convection within a progressive/highly dynamic synoptic pattern. Pronounced surface cyclogenesis is expected with amplification of a vigorous shortwave trough from the central High Plains to the Upper MS Valley. This will yield substantial amplification of low to mid-level flow, with a belt of 70+ kt 500-mb winds extending from eastern KS and western MO through at least IA this afternoon. As the surface cyclone deepens, an attendant cold front will surge eastward into central IA through northwest MO by 00Z. Very steep mid-level lapse rates will overspread the increasingly moist warm sector, supporting aggressive diurnal destabilization especially on the southern fringe of lingering convection/cloud cover. Initial supercell development should occur near the deepening surface cyclone by midday to early afternoon over the Mid-MO Valley. Increasingly widespread thunderstorm development is expected through the afternoon from the Upper MS Valley southward to the Lower MO Valley. Deep-layer shear will support an initial mixed mode of semi-discrete supercells and embedded supercells in clusters. But by late afternoon, upscale growth into a fast-moving arc of bowing line segments and embedded supercells is expected. Additional supercells should also form downstream along the effective warm front/remnant large-scale outflow that advances north in southern to central WI. Very large hail potential will be most likely with the initial supercell development, and with southern extent where semi-discrete storms should persist longest. Tornadoes, some of which should be strong, appear most probable from northern MO northward into southeast MN and southwest to central WI from both supercell and mesovortex processes. How far north strong-tornado potential can be realized will be modulated by the degree of destabilization in the wake of the early-day convection, but low-level SRH will be quite large. Damaging winds will become increasingly likely later in the afternoon into the evening with gusts of 75-90 mph possible as a well-organized QLCS forms. This should tend to be maximized across parts of central/eastern IA into western IL and northern MO. QLCS intensity should subside after dusk, as convection outpaces larger buoyancy, but a damaging wind threat could persist into Lower MI through the Mid-MO Valley. ...Ozarks to central TX... Convective coverage will decrease with southward extent as large-scale ascent focuses northward toward the Upper MS Valley and western Great Lakes. Nevertheless, scattered severe storms are possible during the late afternoon/evening near where the cold front overtakes the dryline in the Ozarks. More isolated convective coverage is expected southwestward along the dryline in central TX. Large buoyancy and ample deep-layer shear will support a primary threat of very large hail in TX. While a mix of large hail, damaging winds, and a few tornadoes will be possible over the Ozarks. ...New England and northeast NY... A low-amplitude shortwave impulse/remnant MCV will move across southern QC and northern New England. This will result in a band of enhanced westerly deep-layer flow from northern NY into ME. A seasonally moist airmass will be in place with surface dewpoints into the low 60s F, with strong heating and steepening low-level lapse rates. Modest MLCAPE and effective shear from 30-35 kt will support a few organized cells. Moderately elongated hodographs suggest marginally severe hail will be possible along with locally damaging wind gusts. ..Grams/Barnes.. 05/21/2024 Read more

MD 0863 CONCERNING SEVERE THUNDERSTORM WATCH 272... FOR NORTHERN IOWA AND SOUTHERN MINNESOTA
Mesoscale Discussion 0863 NWS Storm Prediction Center Norman OK 1134 PM CDT Mon May 20 2024 Areas affected...northern Iowa and southern Minnesota Concerning...Severe Thunderstorm Watch 272... Valid 210434Z - 210600Z The severe weather threat for Severe Thunderstorm Watch 272 continues. SUMMARY...A new severe weather watch does not appear needed, but WW 272 could be locally extended in time for an hour or two. Thunderstorms are expected to remain rather disorganized with diminishing intensities into the overnight hours. DISCUSSION...Ongoing storms are generally embedded with rather modest southwesterly deep-layer mean flow on the order of 20 kt or a bit less. But, due to pronounced veering of wind fields with height, vertical shear may be contributing to the maintenance of vigorous convection. Even as low-level warm advection maintains lift into the overnight hours, it does appear, though, that the risk for severe hail and wind will begin to wane with further boundary-layer cooling. ..Kerr.. 05/21/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ARX...MPX...DMX...FSD... LAT...LON 42889602 43359555 44169324 44159209 43359195 42889250 42259460 42159550 42889602 Read more

MD 0862 CONCERNING TORNADO WATCH 269...273... FOR PARTS OF NORTHEASTERN COLORADO...NORTHWESTERN KANSAS...SOUTHWESTERN NEBRASKA
Mesoscale Discussion 0862 NWS Storm Prediction Center Norman OK 1059 PM CDT Mon May 20 2024 Areas affected...parts of northeastern Colorado...northwestern Kansas...southwestern Nebraska Concerning...Tornado Watch 269...273... Valid 210359Z - 210600Z The severe weather threat for Tornado Watch 269, 273 continues. SUMMARY...Supercells will continue to pose a risk for large hail, locally damaging wind gusts and perhaps a tornado or two during the couple of hours, before storms evolve into a more organized cluster with potential for more widespread severe gusts perhaps occasionally in excess of 75 mph as early as Midnight-2 AM CDT. Additional severe weather watches will likely be needed downstream later tonight. DISCUSSION...Several sustained discrete supercells have evolved in a developing cluster focused within strong warm advection centered around the 700 mb level. This forcing is forecast to continue slowly developing eastward across the western Kansas/Nebraska border area through 05-07Z. Moistening easterly low-level flow beneath this regime (including mid/upper 60s surface dew points advecting across and east of the McCook NE/Hill City KS vicinities) will continue to support increasingly unstable updraft inflow (including CAPE possibly in excess of 2000-3000 J/kg). As this occurs, substantive further upscale growth and organization seems likely in the presence of strong deep-layer shear. While storm motions are initially slow in the presence of modest southwesterly deep-layer mean flow, which may have weakened some this evening, convective evolution during the next few hours probably will include the development of an increasingly well-defined mesoscale convective vortex. Intensifying rear inflow to the south and southeast of this feature is expected to eventually contribute to a more rapid forward propagation and increasing potential for severe surface gusts. ..Kerr.. 05/21/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...GLD...BOU... LAT...LON 40780197 40910110 40900053 39990031 39820136 39690196 39450294 40160315 40780197 Read more

MD 0861 CONCERNING SEVERE THUNDERSTORM WATCH 271... FOR PARTS OF SOUTHEASTERN NEBRASKA AND SOUTHWESTERN IOWA
Mesoscale Discussion 0861 NWS Storm Prediction Center Norman OK 1001 PM CDT Mon May 20 2024 Areas affected...parts of southeastern Nebraska and southwestern Iowa Concerning...Severe Thunderstorm Watch 271... Valid 210301Z - 210500Z The severe weather threat for Severe Thunderstorm Watch 271 continues. SUMMARY...Stronger storms capable of producing severe hail and wind are becoming more widely scattered to isolated and likely to diminish further through around Midnight CDT. It is not clear that a new severe weather watch will be needed thereafter, until much later tonight. DISCUSSION...Based on the Rapid Refresh, and convective trends, warming in the 700-500 mb layer nosing across the Kansas border into south central and southeastern Nebraska has become increasingly inhibitive to convection, to the south and west of lingering strong storms now northwest of Lincoln and west/north of Omaha. Coupled with continued boundary-layer cooling during the next few hours, generally weakening thunderstorm intensities with diminishing risk for severe hail and wind are anticipated through the 04-06Z time frame. However, upscale growing convection currently still organizing across parts of northeastern Colorado could be accompanied by increasing severe weather potential into the region later tonight (after 4 AM CDT). ..Kerr.. 05/21/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DMX...OAX...GID... LAT...LON 41829647 41789482 41509449 40979502 40859567 40819602 40829672 40839745 41829647 Read more

WW 0273 Status Updates
STATUS REPORT ON WW 273 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..KERR..05/21/24 ATTN...WFO...GLD...LBF... STATUS REPORT FOR WT 273 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS COC125-210540- CO . COLORADO COUNTIES INCLUDED ARE YUMA KSC023-039-137-153-210540- KS . KANSAS COUNTIES INCLUDED ARE CHEYENNE DECATUR NORTON RAWLINS NEC005-029-049-057-063-069-085-087-101-111-113-117-135-145- 210540- NE . NEBRASKA COUNTIES INCLUDED ARE ARTHUR CHASE DEUEL DUNDY FRONTIER GARDEN HAYES HITCHCOCK KEITH Read more

WW 0273 Status Updates
STATUS REPORT ON WW 273 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..KERR..05/21/24 ATTN...WFO...GLD...LBF... STATUS REPORT FOR WT 273 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS COC125-210540- CO . COLORADO COUNTIES INCLUDED ARE YUMA KSC023-039-137-153-210540- KS . KANSAS COUNTIES INCLUDED ARE CHEYENNE DECATUR NORTON RAWLINS NEC005-029-049-057-063-069-085-087-101-111-113-117-135-145- 210540- NE . NEBRASKA COUNTIES INCLUDED ARE ARTHUR CHASE DEUEL DUNDY FRONTIER GARDEN HAYES HITCHCOCK KEITH Read more

WW 0269 Status Updates
STATUS REPORT ON WW 269 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 SSW AKO TO 10 SW AKO TO 10 W IML. REMAINING VALID PORTION OF WW 269 MAY BE ALLOWED TO EXPIRE AT 21/05Z. ..KERR..05/21/24 ATTN...WFO...BOU...GLD... STATUS REPORT FOR WT 269 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS COC121-210500- CO . COLORADO COUNTIES INCLUDED ARE WASHINGTON THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 0269 Status Updates
STATUS REPORT ON WW 269 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 SSW AKO TO 10 SW AKO TO 10 W IML. REMAINING VALID PORTION OF WW 269 MAY BE ALLOWED TO EXPIRE AT 21/05Z. ..KERR..05/21/24 ATTN...WFO...BOU...GLD... STATUS REPORT FOR WT 269 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS COC121-210500- CO . COLORADO COUNTIES INCLUDED ARE WASHINGTON THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more