Severe Storms

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0753 AM CDT Sun Aug 18 2024 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR KANSAS INTO THE WESTERN OZARKS...AND FROM THE MID-ATLANTIC STATES INTO THE DEEP SOUTH... ...SUMMARY... Scattered severe gusts are possible from northern Kansas to the western part of the Ozark Plateau, and in a separate area from the Mid-Atlantic States to the Deep South this afternoon to early evening. ...Rockies/Central Plains... Water-vapor imagery this morning indicates a short-wave trough cresting the Rockies mid-level ridge. This feature is forecast to move southeast with an enhanced belt of 500-mb flow (40-50 kt) moving into the Ozarks late. The 00z MPAS-HT-NSSL model seemed to reasonably depict elevated convection and a small severe cluster this morning over SD and northern NE. Other model guidance varies considerably on the handling of this early day storm activity. A risk for large hail will continue across east-central NE through the late morning in association with WAA-related storms favoring the eastern gradient of moisture/instability where isentropic lift will be maximized. Based on several factors 1) the aforementioned MPAS guidance, 2) enhanced mid to upper-level northwesterly flow per OAX, TOP, and SGF 12 UTC raobs, and a reservoir of higher theta-e across northern OK into KS, it seems possible a forward-propagating cluster/MCS may evolve this afternoon from KS into the western Ozarks. Have increased severe probabilities to account for this forecast evolution. ...Middle Atlantic to Deep South... Not much change in thinking from the prior forecast in that a Great Lakes/OH Valley upper trough will shift east and reach the spine of the Appalachians by early evening. Modest 500mb flow should extend within the base of the trough into the Mid-Atlantic states where shear profiles will be most supportive of organized storm structures (including multicells and transient supercells). Damaging gusts (50-65 mph) will likely be the primary risk, but some risk for hail and perhaps a brief tornado can be expected. The trailing portion of the front across the Deep South will not be particularly convergent as it surges into GA-AL-MS. However, a seasonably moist airmass (15-16 g/kg lowest 100-mb mean mixing ratios) sampled by the 12 UTC Jackson, MS east to the coastal Carolinas raob sites, will undergo strong heating through mid afternoon. Several clusters of strong to severe/damaging thunderstorm clusters are forecast to evolve by mid to late afternoon and push towards the coastal areas by early evening. ...Interior West... Scattered to numerous diurnal thunderstorms are forecast to develop on the western/northern periphery of a mid-level anticyclone centered over northeast NM. An ongoing thunderstorm cluster over central AZ will continue to move northward through the midday. This convection appears to be partly influenced by a weak disturbance of convective origin and is partly evident some augmenting of mid-level flow in the KIWA (Phoenix WSR-88D) VAD data. As a result, greater storm coverage will likely be associated with this feature as it moves into a destabilizing airmass across southern UT by early to mid afternoon. Severe gusts (60-75 mph) are possible with this diurnally enhanced activity from the UT/AZ border northward into MT. ..Smith/Mosier.. 08/18/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0753 AM CDT Sun Aug 18 2024 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR KANSAS INTO THE WESTERN OZARKS...AND FROM THE MID-ATLANTIC STATES INTO THE DEEP SOUTH... ...SUMMARY... Scattered severe gusts are possible from northern Kansas to the western part of the Ozark Plateau, and in a separate area from the Mid-Atlantic States to the Deep South this afternoon to early evening. ...Rockies/Central Plains... Water-vapor imagery this morning indicates a short-wave trough cresting the Rockies mid-level ridge. This feature is forecast to move southeast with an enhanced belt of 500-mb flow (40-50 kt) moving into the Ozarks late. The 00z MPAS-HT-NSSL model seemed to reasonably depict elevated convection and a small severe cluster this morning over SD and northern NE. Other model guidance varies considerably on the handling of this early day storm activity. A risk for large hail will continue across east-central NE through the late morning in association with WAA-related storms favoring the eastern gradient of moisture/instability where isentropic lift will be maximized. Based on several factors 1) the aforementioned MPAS guidance, 2) enhanced mid to upper-level northwesterly flow per OAX, TOP, and SGF 12 UTC raobs, and a reservoir of higher theta-e across northern OK into KS, it seems possible a forward-propagating cluster/MCS may evolve this afternoon from KS into the western Ozarks. Have increased severe probabilities to account for this forecast evolution. ...Middle Atlantic to Deep South... Not much change in thinking from the prior forecast in that a Great Lakes/OH Valley upper trough will shift east and reach the spine of the Appalachians by early evening. Modest 500mb flow should extend within the base of the trough into the Mid-Atlantic states where shear profiles will be most supportive of organized storm structures (including multicells and transient supercells). Damaging gusts (50-65 mph) will likely be the primary risk, but some risk for hail and perhaps a brief tornado can be expected. The trailing portion of the front across the Deep South will not be particularly convergent as it surges into GA-AL-MS. However, a seasonably moist airmass (15-16 g/kg lowest 100-mb mean mixing ratios) sampled by the 12 UTC Jackson, MS east to the coastal Carolinas raob sites, will undergo strong heating through mid afternoon. Several clusters of strong to severe/damaging thunderstorm clusters are forecast to evolve by mid to late afternoon and push towards the coastal areas by early evening. ...Interior West... Scattered to numerous diurnal thunderstorms are forecast to develop on the western/northern periphery of a mid-level anticyclone centered over northeast NM. An ongoing thunderstorm cluster over central AZ will continue to move northward through the midday. This convection appears to be partly influenced by a weak disturbance of convective origin and is partly evident some augmenting of mid-level flow in the KIWA (Phoenix WSR-88D) VAD data. As a result, greater storm coverage will likely be associated with this feature as it moves into a destabilizing airmass across southern UT by early to mid afternoon. Severe gusts (60-75 mph) are possible with this diurnally enhanced activity from the UT/AZ border northward into MT. ..Smith/Mosier.. 08/18/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0753 AM CDT Sun Aug 18 2024 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR KANSAS INTO THE WESTERN OZARKS...AND FROM THE MID-ATLANTIC STATES INTO THE DEEP SOUTH... ...SUMMARY... Scattered severe gusts are possible from northern Kansas to the western part of the Ozark Plateau, and in a separate area from the Mid-Atlantic States to the Deep South this afternoon to early evening. ...Rockies/Central Plains... Water-vapor imagery this morning indicates a short-wave trough cresting the Rockies mid-level ridge. This feature is forecast to move southeast with an enhanced belt of 500-mb flow (40-50 kt) moving into the Ozarks late. The 00z MPAS-HT-NSSL model seemed to reasonably depict elevated convection and a small severe cluster this morning over SD and northern NE. Other model guidance varies considerably on the handling of this early day storm activity. A risk for large hail will continue across east-central NE through the late morning in association with WAA-related storms favoring the eastern gradient of moisture/instability where isentropic lift will be maximized. Based on several factors 1) the aforementioned MPAS guidance, 2) enhanced mid to upper-level northwesterly flow per OAX, TOP, and SGF 12 UTC raobs, and a reservoir of higher theta-e across northern OK into KS, it seems possible a forward-propagating cluster/MCS may evolve this afternoon from KS into the western Ozarks. Have increased severe probabilities to account for this forecast evolution. ...Middle Atlantic to Deep South... Not much change in thinking from the prior forecast in that a Great Lakes/OH Valley upper trough will shift east and reach the spine of the Appalachians by early evening. Modest 500mb flow should extend within the base of the trough into the Mid-Atlantic states where shear profiles will be most supportive of organized storm structures (including multicells and transient supercells). Damaging gusts (50-65 mph) will likely be the primary risk, but some risk for hail and perhaps a brief tornado can be expected. The trailing portion of the front across the Deep South will not be particularly convergent as it surges into GA-AL-MS. However, a seasonably moist airmass (15-16 g/kg lowest 100-mb mean mixing ratios) sampled by the 12 UTC Jackson, MS east to the coastal Carolinas raob sites, will undergo strong heating through mid afternoon. Several clusters of strong to severe/damaging thunderstorm clusters are forecast to evolve by mid to late afternoon and push towards the coastal areas by early evening. ...Interior West... Scattered to numerous diurnal thunderstorms are forecast to develop on the western/northern periphery of a mid-level anticyclone centered over northeast NM. An ongoing thunderstorm cluster over central AZ will continue to move northward through the midday. This convection appears to be partly influenced by a weak disturbance of convective origin and is partly evident some augmenting of mid-level flow in the KIWA (Phoenix WSR-88D) VAD data. As a result, greater storm coverage will likely be associated with this feature as it moves into a destabilizing airmass across southern UT by early to mid afternoon. Severe gusts (60-75 mph) are possible with this diurnally enhanced activity from the UT/AZ border northward into MT. ..Smith/Mosier.. 08/18/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0753 AM CDT Sun Aug 18 2024 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR KANSAS INTO THE WESTERN OZARKS...AND FROM THE MID-ATLANTIC STATES INTO THE DEEP SOUTH... ...SUMMARY... Scattered severe gusts are possible from northern Kansas to the western part of the Ozark Plateau, and in a separate area from the Mid-Atlantic States to the Deep South this afternoon to early evening. ...Rockies/Central Plains... Water-vapor imagery this morning indicates a short-wave trough cresting the Rockies mid-level ridge. This feature is forecast to move southeast with an enhanced belt of 500-mb flow (40-50 kt) moving into the Ozarks late. The 00z MPAS-HT-NSSL model seemed to reasonably depict elevated convection and a small severe cluster this morning over SD and northern NE. Other model guidance varies considerably on the handling of this early day storm activity. A risk for large hail will continue across east-central NE through the late morning in association with WAA-related storms favoring the eastern gradient of moisture/instability where isentropic lift will be maximized. Based on several factors 1) the aforementioned MPAS guidance, 2) enhanced mid to upper-level northwesterly flow per OAX, TOP, and SGF 12 UTC raobs, and a reservoir of higher theta-e across northern OK into KS, it seems possible a forward-propagating cluster/MCS may evolve this afternoon from KS into the western Ozarks. Have increased severe probabilities to account for this forecast evolution. ...Middle Atlantic to Deep South... Not much change in thinking from the prior forecast in that a Great Lakes/OH Valley upper trough will shift east and reach the spine of the Appalachians by early evening. Modest 500mb flow should extend within the base of the trough into the Mid-Atlantic states where shear profiles will be most supportive of organized storm structures (including multicells and transient supercells). Damaging gusts (50-65 mph) will likely be the primary risk, but some risk for hail and perhaps a brief tornado can be expected. The trailing portion of the front across the Deep South will not be particularly convergent as it surges into GA-AL-MS. However, a seasonably moist airmass (15-16 g/kg lowest 100-mb mean mixing ratios) sampled by the 12 UTC Jackson, MS east to the coastal Carolinas raob sites, will undergo strong heating through mid afternoon. Several clusters of strong to severe/damaging thunderstorm clusters are forecast to evolve by mid to late afternoon and push towards the coastal areas by early evening. ...Interior West... Scattered to numerous diurnal thunderstorms are forecast to develop on the western/northern periphery of a mid-level anticyclone centered over northeast NM. An ongoing thunderstorm cluster over central AZ will continue to move northward through the midday. This convection appears to be partly influenced by a weak disturbance of convective origin and is partly evident some augmenting of mid-level flow in the KIWA (Phoenix WSR-88D) VAD data. As a result, greater storm coverage will likely be associated with this feature as it moves into a destabilizing airmass across southern UT by early to mid afternoon. Severe gusts (60-75 mph) are possible with this diurnally enhanced activity from the UT/AZ border northward into MT. ..Smith/Mosier.. 08/18/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0753 AM CDT Sun Aug 18 2024 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR KANSAS INTO THE WESTERN OZARKS...AND FROM THE MID-ATLANTIC STATES INTO THE DEEP SOUTH... ...SUMMARY... Scattered severe gusts are possible from northern Kansas to the western part of the Ozark Plateau, and in a separate area from the Mid-Atlantic States to the Deep South this afternoon to early evening. ...Rockies/Central Plains... Water-vapor imagery this morning indicates a short-wave trough cresting the Rockies mid-level ridge. This feature is forecast to move southeast with an enhanced belt of 500-mb flow (40-50 kt) moving into the Ozarks late. The 00z MPAS-HT-NSSL model seemed to reasonably depict elevated convection and a small severe cluster this morning over SD and northern NE. Other model guidance varies considerably on the handling of this early day storm activity. A risk for large hail will continue across east-central NE through the late morning in association with WAA-related storms favoring the eastern gradient of moisture/instability where isentropic lift will be maximized. Based on several factors 1) the aforementioned MPAS guidance, 2) enhanced mid to upper-level northwesterly flow per OAX, TOP, and SGF 12 UTC raobs, and a reservoir of higher theta-e across northern OK into KS, it seems possible a forward-propagating cluster/MCS may evolve this afternoon from KS into the western Ozarks. Have increased severe probabilities to account for this forecast evolution. ...Middle Atlantic to Deep South... Not much change in thinking from the prior forecast in that a Great Lakes/OH Valley upper trough will shift east and reach the spine of the Appalachians by early evening. Modest 500mb flow should extend within the base of the trough into the Mid-Atlantic states where shear profiles will be most supportive of organized storm structures (including multicells and transient supercells). Damaging gusts (50-65 mph) will likely be the primary risk, but some risk for hail and perhaps a brief tornado can be expected. The trailing portion of the front across the Deep South will not be particularly convergent as it surges into GA-AL-MS. However, a seasonably moist airmass (15-16 g/kg lowest 100-mb mean mixing ratios) sampled by the 12 UTC Jackson, MS east to the coastal Carolinas raob sites, will undergo strong heating through mid afternoon. Several clusters of strong to severe/damaging thunderstorm clusters are forecast to evolve by mid to late afternoon and push towards the coastal areas by early evening. ...Interior West... Scattered to numerous diurnal thunderstorms are forecast to develop on the western/northern periphery of a mid-level anticyclone centered over northeast NM. An ongoing thunderstorm cluster over central AZ will continue to move northward through the midday. This convection appears to be partly influenced by a weak disturbance of convective origin and is partly evident some augmenting of mid-level flow in the KIWA (Phoenix WSR-88D) VAD data. As a result, greater storm coverage will likely be associated with this feature as it moves into a destabilizing airmass across southern UT by early to mid afternoon. Severe gusts (60-75 mph) are possible with this diurnally enhanced activity from the UT/AZ border northward into MT. ..Smith/Mosier.. 08/18/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0753 AM CDT Sun Aug 18 2024 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR KANSAS INTO THE WESTERN OZARKS...AND FROM THE MID-ATLANTIC STATES INTO THE DEEP SOUTH... ...SUMMARY... Scattered severe gusts are possible from northern Kansas to the western part of the Ozark Plateau, and in a separate area from the Mid-Atlantic States to the Deep South this afternoon to early evening. ...Rockies/Central Plains... Water-vapor imagery this morning indicates a short-wave trough cresting the Rockies mid-level ridge. This feature is forecast to move southeast with an enhanced belt of 500-mb flow (40-50 kt) moving into the Ozarks late. The 00z MPAS-HT-NSSL model seemed to reasonably depict elevated convection and a small severe cluster this morning over SD and northern NE. Other model guidance varies considerably on the handling of this early day storm activity. A risk for large hail will continue across east-central NE through the late morning in association with WAA-related storms favoring the eastern gradient of moisture/instability where isentropic lift will be maximized. Based on several factors 1) the aforementioned MPAS guidance, 2) enhanced mid to upper-level northwesterly flow per OAX, TOP, and SGF 12 UTC raobs, and a reservoir of higher theta-e across northern OK into KS, it seems possible a forward-propagating cluster/MCS may evolve this afternoon from KS into the western Ozarks. Have increased severe probabilities to account for this forecast evolution. ...Middle Atlantic to Deep South... Not much change in thinking from the prior forecast in that a Great Lakes/OH Valley upper trough will shift east and reach the spine of the Appalachians by early evening. Modest 500mb flow should extend within the base of the trough into the Mid-Atlantic states where shear profiles will be most supportive of organized storm structures (including multicells and transient supercells). Damaging gusts (50-65 mph) will likely be the primary risk, but some risk for hail and perhaps a brief tornado can be expected. The trailing portion of the front across the Deep South will not be particularly convergent as it surges into GA-AL-MS. However, a seasonably moist airmass (15-16 g/kg lowest 100-mb mean mixing ratios) sampled by the 12 UTC Jackson, MS east to the coastal Carolinas raob sites, will undergo strong heating through mid afternoon. Several clusters of strong to severe/damaging thunderstorm clusters are forecast to evolve by mid to late afternoon and push towards the coastal areas by early evening. ...Interior West... Scattered to numerous diurnal thunderstorms are forecast to develop on the western/northern periphery of a mid-level anticyclone centered over northeast NM. An ongoing thunderstorm cluster over central AZ will continue to move northward through the midday. This convection appears to be partly influenced by a weak disturbance of convective origin and is partly evident some augmenting of mid-level flow in the KIWA (Phoenix WSR-88D) VAD data. As a result, greater storm coverage will likely be associated with this feature as it moves into a destabilizing airmass across southern UT by early to mid afternoon. Severe gusts (60-75 mph) are possible with this diurnally enhanced activity from the UT/AZ border northward into MT. ..Smith/Mosier.. 08/18/2024 Read more

MD 1940 CONCERNING SEVERE THUNDERSTORM WATCH 633... FOR SOUTH-CENTRAL SD...NORTH-CENTRAL/CENTRAL NE
Mesoscale Discussion 1940 NWS Storm Prediction Center Norman OK 0550 AM CDT Sun Aug 18 2024 Areas affected...South-Central SD...North-Central/Central NE Concerning...Severe Thunderstorm Watch 633... Valid 181050Z - 181245Z The severe weather threat for Severe Thunderstorm Watch 633 continues. SUMMARY...Threat for large hail and strong gusts will continues across far south-central South Dakota and north-central/central Nebraska for the next few hours. DISCUSSION...Lead supercell within the elevated cluster of showers and thunderstorms extending from central SD into far north-central NE has maintained its intensity over the past hour while much of the other convection has weakened. Organized character of this storm suggests it will remain strong as it continues southeastward into more of north-central NE over the next hour or so. Thereafter, displacement from the warm-air advection responsible of this storm's initiation could result in a gradual weakening. Until this weakening begins, both large hail and strong gusts are possible with this storm. Farther southwest (i.e. across central NE), elevated thunderstorms continue to push eastward into central NE. These storms developed along the leading edge of the greater large-scale forcing for ascent attendant to a shortwave trough emerging into the central High Plains. Despite moderate buoyancy, these storms have been slow to strengthen. Some strengthening is possible over the next hour or so as forcing for ascent persists and vertical shear increases slightly. Large hail is the primary risk with these storms. ..Mosier.. 08/18/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FSD...OAX...ABR...GID...LBF...UNR... LAT...LON 43830005 43739840 42689760 41229830 41160076 43180075 43830005 Read more

WW 0633 Status Updates
STATUS REPORT ON WW 633 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 NNE VTN TO 35 W YKN. ..MOSIER..08/18/24 ATTN...WFO...OAX...LBF...GID...FSD...UNR... STATUS REPORT FOR WS 633 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NEC003-009-011-015-017-041-071-077-089-093-103-107-115-121-125- 139-143-149-163-175-183-181340- NE . NEBRASKA COUNTIES INCLUDED ARE ANTELOPE BLAINE BOONE BOYD BROWN CUSTER GARFIELD GREELEY HOLT HOWARD KEYA PAHA KNOX LOUP MERRICK NANCE PIERCE POLK ROCK SHERMAN VALLEY WHEELER 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

MD 1939 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR SOUTH-CENTRAL SD...NORTH-CENTRAL NE
Mesoscale Discussion 1939 NWS Storm Prediction Center Norman OK 0223 AM CDT Sun Aug 18 2024 Areas affected...South-Central SD...North-Central NE Concerning...Severe potential...Watch unlikely Valid 180723Z - 181000Z Probability of Watch Issuance...20 percent SUMMARY...Large hail is possible across south-central South Dakota and adjacent north-central Nebraska for the next few hours. DISCUSSION...Isolated thunderstorms have developed across south-central SD amid the warm-air advection regime fostered by the modest low-level jet over the central High Plains. Moderate to strong buoyancy (i.e. MUCAPE from 2000 to 3000 J/kg) is in place from southwest/south-central SD into central NE, with these storms developing near the maximum within this corridor. There is a sharp gradient in buoyancy with northeastward extent, with MUCAPE dropping from 3000 J/kg across southwest SD to less than 500 J/kg across eastern NE. This lack of buoyancy across eastern SD will likely limit storm development to the northeast of the ongoing storms until later this morning. The northwesterly deep-layer vertical shear suggests a southeasterly storm motion will be favored as updrafts mature. Large hail is possible with these storms for the next hour or two. Additional thunderstorm development appears possible to the southwest of the ongoing storms, fostered by a combination of warm-air advection and strengthening large-scale ascent attendant to a shortwave trough currently progressing northeastward through the central Rockies. The aforementioned corridor of moderate to strong buoyancy will support strong updrafts, with the moderate deep-layer vertical shear supporting updraft organization. Consequently, a few storms may become strong enough to produce large hail. ..Mosier/Smith.. 08/18/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FSD...ABR...GID...LBF...UNR...CYS... LAT...LON 44480225 44359977 42269836 41249980 41140134 43130293 44480225 Read more

WW 0633 Status Updates
STATUS FOR WATCH 0633 HAS NOT BEEN ISSUED YET Read more

WW 0633 Status Updates
STATUS FOR WATCH 0633 HAS NOT BEEN ISSUED YET Read more

WW 0633 Status Updates
STATUS FOR WATCH 0633 HAS NOT BEEN ISSUED YET Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0350 AM CDT Sun Aug 18 2024 Valid 211200Z - 261200Z ...DISCUSSION... ...Wednesday/Day 4 to Friday/Day 6... An upper-level ridge is forecast to gradually deamplify, moving from the northern Plains on Wednesday to the Great Lakes on Friday. An axis of instability will likely remain in the central and northern Plains from mid to late week, where isolated to scattered thunderstorms are expected to develop each afternoon and evening. The strongest instability is forecast over the Dakotas on Wednesday, with the ECMWF having SBCAPE peak above 4000 J/kg along the instability axis. This, combined with 0-6 km shear in the 30 to 40 knot range, would support isolated supercell development. Large hail and severe wind gusts would be the primary threats. However, some solutions suggest that the upper-level ridge will be slower to move eastward, which would keep convection more isolated on Wednesday. For this reason, will not add a threat area for Wednesday. A similar setup is forecast on Thursday and Friday, which would support a marginal severe threat across the northern Plains each afternoon and evening. ...Saturday/Day 7 and Sunday/Day 8... On Saturday, some of the medium-range models have an upper-level trough moving through the northern Rockies and Intermountain West. Southwesterly flow would be in place across much of the north-central U.S. Ahead of this feature, scattered thunderstorm would be possible across parts of the northern High Plains and Dakotas. Under this scenario, which is favored by the ECMWF, severe storms would be possible in parts of the northern Plains extending south-southeastward along the instability axis into the mid Missouri Valley. The severe threat would be shifted eastward into the parts of the upper Mississippi Valley on Sunday. For the weekend, other models are considerably slower with the progression of the western U.S. upper-level trough, which adds a lot of forecast uncertainty. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0350 AM CDT Sun Aug 18 2024 Valid 211200Z - 261200Z ...DISCUSSION... ...Wednesday/Day 4 to Friday/Day 6... An upper-level ridge is forecast to gradually deamplify, moving from the northern Plains on Wednesday to the Great Lakes on Friday. An axis of instability will likely remain in the central and northern Plains from mid to late week, where isolated to scattered thunderstorms are expected to develop each afternoon and evening. The strongest instability is forecast over the Dakotas on Wednesday, with the ECMWF having SBCAPE peak above 4000 J/kg along the instability axis. This, combined with 0-6 km shear in the 30 to 40 knot range, would support isolated supercell development. Large hail and severe wind gusts would be the primary threats. However, some solutions suggest that the upper-level ridge will be slower to move eastward, which would keep convection more isolated on Wednesday. For this reason, will not add a threat area for Wednesday. A similar setup is forecast on Thursday and Friday, which would support a marginal severe threat across the northern Plains each afternoon and evening. ...Saturday/Day 7 and Sunday/Day 8... On Saturday, some of the medium-range models have an upper-level trough moving through the northern Rockies and Intermountain West. Southwesterly flow would be in place across much of the north-central U.S. Ahead of this feature, scattered thunderstorm would be possible across parts of the northern High Plains and Dakotas. Under this scenario, which is favored by the ECMWF, severe storms would be possible in parts of the northern Plains extending south-southeastward along the instability axis into the mid Missouri Valley. The severe threat would be shifted eastward into the parts of the upper Mississippi Valley on Sunday. For the weekend, other models are considerably slower with the progression of the western U.S. upper-level trough, which adds a lot of forecast uncertainty. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0350 AM CDT Sun Aug 18 2024 Valid 211200Z - 261200Z ...DISCUSSION... ...Wednesday/Day 4 to Friday/Day 6... An upper-level ridge is forecast to gradually deamplify, moving from the northern Plains on Wednesday to the Great Lakes on Friday. An axis of instability will likely remain in the central and northern Plains from mid to late week, where isolated to scattered thunderstorms are expected to develop each afternoon and evening. The strongest instability is forecast over the Dakotas on Wednesday, with the ECMWF having SBCAPE peak above 4000 J/kg along the instability axis. This, combined with 0-6 km shear in the 30 to 40 knot range, would support isolated supercell development. Large hail and severe wind gusts would be the primary threats. However, some solutions suggest that the upper-level ridge will be slower to move eastward, which would keep convection more isolated on Wednesday. For this reason, will not add a threat area for Wednesday. A similar setup is forecast on Thursday and Friday, which would support a marginal severe threat across the northern Plains each afternoon and evening. ...Saturday/Day 7 and Sunday/Day 8... On Saturday, some of the medium-range models have an upper-level trough moving through the northern Rockies and Intermountain West. Southwesterly flow would be in place across much of the north-central U.S. Ahead of this feature, scattered thunderstorm would be possible across parts of the northern High Plains and Dakotas. Under this scenario, which is favored by the ECMWF, severe storms would be possible in parts of the northern Plains extending south-southeastward along the instability axis into the mid Missouri Valley. The severe threat would be shifted eastward into the parts of the upper Mississippi Valley on Sunday. For the weekend, other models are considerably slower with the progression of the western U.S. upper-level trough, which adds a lot of forecast uncertainty. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0350 AM CDT Sun Aug 18 2024 Valid 211200Z - 261200Z ...DISCUSSION... ...Wednesday/Day 4 to Friday/Day 6... An upper-level ridge is forecast to gradually deamplify, moving from the northern Plains on Wednesday to the Great Lakes on Friday. An axis of instability will likely remain in the central and northern Plains from mid to late week, where isolated to scattered thunderstorms are expected to develop each afternoon and evening. The strongest instability is forecast over the Dakotas on Wednesday, with the ECMWF having SBCAPE peak above 4000 J/kg along the instability axis. This, combined with 0-6 km shear in the 30 to 40 knot range, would support isolated supercell development. Large hail and severe wind gusts would be the primary threats. However, some solutions suggest that the upper-level ridge will be slower to move eastward, which would keep convection more isolated on Wednesday. For this reason, will not add a threat area for Wednesday. A similar setup is forecast on Thursday and Friday, which would support a marginal severe threat across the northern Plains each afternoon and evening. ...Saturday/Day 7 and Sunday/Day 8... On Saturday, some of the medium-range models have an upper-level trough moving through the northern Rockies and Intermountain West. Southwesterly flow would be in place across much of the north-central U.S. Ahead of this feature, scattered thunderstorm would be possible across parts of the northern High Plains and Dakotas. Under this scenario, which is favored by the ECMWF, severe storms would be possible in parts of the northern Plains extending south-southeastward along the instability axis into the mid Missouri Valley. The severe threat would be shifted eastward into the parts of the upper Mississippi Valley on Sunday. For the weekend, other models are considerably slower with the progression of the western U.S. upper-level trough, which adds a lot of forecast uncertainty. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0350 AM CDT Sun Aug 18 2024 Valid 211200Z - 261200Z ...DISCUSSION... ...Wednesday/Day 4 to Friday/Day 6... An upper-level ridge is forecast to gradually deamplify, moving from the northern Plains on Wednesday to the Great Lakes on Friday. An axis of instability will likely remain in the central and northern Plains from mid to late week, where isolated to scattered thunderstorms are expected to develop each afternoon and evening. The strongest instability is forecast over the Dakotas on Wednesday, with the ECMWF having SBCAPE peak above 4000 J/kg along the instability axis. This, combined with 0-6 km shear in the 30 to 40 knot range, would support isolated supercell development. Large hail and severe wind gusts would be the primary threats. However, some solutions suggest that the upper-level ridge will be slower to move eastward, which would keep convection more isolated on Wednesday. For this reason, will not add a threat area for Wednesday. A similar setup is forecast on Thursday and Friday, which would support a marginal severe threat across the northern Plains each afternoon and evening. ...Saturday/Day 7 and Sunday/Day 8... On Saturday, some of the medium-range models have an upper-level trough moving through the northern Rockies and Intermountain West. Southwesterly flow would be in place across much of the north-central U.S. Ahead of this feature, scattered thunderstorm would be possible across parts of the northern High Plains and Dakotas. Under this scenario, which is favored by the ECMWF, severe storms would be possible in parts of the northern Plains extending south-southeastward along the instability axis into the mid Missouri Valley. The severe threat would be shifted eastward into the parts of the upper Mississippi Valley on Sunday. For the weekend, other models are considerably slower with the progression of the western U.S. upper-level trough, which adds a lot of forecast uncertainty. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0350 AM CDT Sun Aug 18 2024 Valid 211200Z - 261200Z ...DISCUSSION... ...Wednesday/Day 4 to Friday/Day 6... An upper-level ridge is forecast to gradually deamplify, moving from the northern Plains on Wednesday to the Great Lakes on Friday. An axis of instability will likely remain in the central and northern Plains from mid to late week, where isolated to scattered thunderstorms are expected to develop each afternoon and evening. The strongest instability is forecast over the Dakotas on Wednesday, with the ECMWF having SBCAPE peak above 4000 J/kg along the instability axis. This, combined with 0-6 km shear in the 30 to 40 knot range, would support isolated supercell development. Large hail and severe wind gusts would be the primary threats. However, some solutions suggest that the upper-level ridge will be slower to move eastward, which would keep convection more isolated on Wednesday. For this reason, will not add a threat area for Wednesday. A similar setup is forecast on Thursday and Friday, which would support a marginal severe threat across the northern Plains each afternoon and evening. ...Saturday/Day 7 and Sunday/Day 8... On Saturday, some of the medium-range models have an upper-level trough moving through the northern Rockies and Intermountain West. Southwesterly flow would be in place across much of the north-central U.S. Ahead of this feature, scattered thunderstorm would be possible across parts of the northern High Plains and Dakotas. Under this scenario, which is favored by the ECMWF, severe storms would be possible in parts of the northern Plains extending south-southeastward along the instability axis into the mid Missouri Valley. The severe threat would be shifted eastward into the parts of the upper Mississippi Valley on Sunday. For the weekend, other models are considerably slower with the progression of the western U.S. upper-level trough, which adds a lot of forecast uncertainty. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0350 AM CDT Sun Aug 18 2024 Valid 211200Z - 261200Z ...DISCUSSION... ...Wednesday/Day 4 to Friday/Day 6... An upper-level ridge is forecast to gradually deamplify, moving from the northern Plains on Wednesday to the Great Lakes on Friday. An axis of instability will likely remain in the central and northern Plains from mid to late week, where isolated to scattered thunderstorms are expected to develop each afternoon and evening. The strongest instability is forecast over the Dakotas on Wednesday, with the ECMWF having SBCAPE peak above 4000 J/kg along the instability axis. This, combined with 0-6 km shear in the 30 to 40 knot range, would support isolated supercell development. Large hail and severe wind gusts would be the primary threats. However, some solutions suggest that the upper-level ridge will be slower to move eastward, which would keep convection more isolated on Wednesday. For this reason, will not add a threat area for Wednesday. A similar setup is forecast on Thursday and Friday, which would support a marginal severe threat across the northern Plains each afternoon and evening. ...Saturday/Day 7 and Sunday/Day 8... On Saturday, some of the medium-range models have an upper-level trough moving through the northern Rockies and Intermountain West. Southwesterly flow would be in place across much of the north-central U.S. Ahead of this feature, scattered thunderstorm would be possible across parts of the northern High Plains and Dakotas. Under this scenario, which is favored by the ECMWF, severe storms would be possible in parts of the northern Plains extending south-southeastward along the instability axis into the mid Missouri Valley. The severe threat would be shifted eastward into the parts of the upper Mississippi Valley on Sunday. For the weekend, other models are considerably slower with the progression of the western U.S. upper-level trough, which adds a lot of forecast uncertainty. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0350 AM CDT Sun Aug 18 2024 Valid 211200Z - 261200Z ...DISCUSSION... ...Wednesday/Day 4 to Friday/Day 6... An upper-level ridge is forecast to gradually deamplify, moving from the northern Plains on Wednesday to the Great Lakes on Friday. An axis of instability will likely remain in the central and northern Plains from mid to late week, where isolated to scattered thunderstorms are expected to develop each afternoon and evening. The strongest instability is forecast over the Dakotas on Wednesday, with the ECMWF having SBCAPE peak above 4000 J/kg along the instability axis. This, combined with 0-6 km shear in the 30 to 40 knot range, would support isolated supercell development. Large hail and severe wind gusts would be the primary threats. However, some solutions suggest that the upper-level ridge will be slower to move eastward, which would keep convection more isolated on Wednesday. For this reason, will not add a threat area for Wednesday. A similar setup is forecast on Thursday and Friday, which would support a marginal severe threat across the northern Plains each afternoon and evening. ...Saturday/Day 7 and Sunday/Day 8... On Saturday, some of the medium-range models have an upper-level trough moving through the northern Rockies and Intermountain West. Southwesterly flow would be in place across much of the north-central U.S. Ahead of this feature, scattered thunderstorm would be possible across parts of the northern High Plains and Dakotas. Under this scenario, which is favored by the ECMWF, severe storms would be possible in parts of the northern Plains extending south-southeastward along the instability axis into the mid Missouri Valley. The severe threat would be shifted eastward into the parts of the upper Mississippi Valley on Sunday. For the weekend, other models are considerably slower with the progression of the western U.S. upper-level trough, which adds a lot of forecast uncertainty. Read more