Severe Storms

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0142 AM CDT Thu Aug 08 2019 Valid 091200Z - 101200Z ...Synopsis... The overall synoptic pattern should remain similar throughout the D2/Thu forecast period. A longwave trough will begin to make eastward progression toward Oregon and northern California, resulting in strengthening mid-level flow from Nevada northward through western Idaho as a mid-level ridge keeps hold over the central Rockies and vicinity. Lift from the approaching trough and maintenance of mid-level moisture should promote a few thunderstorms during the afternoon and evening, while strengthening wind fields will result in elevated to locally critical fire weather in the western Great Basin. ...Much of Nevada and far northeastern California for dry/windy conditions... Vertical mixing processes beneath strengthening flow aloft and a strengthening surface trough across the region will result in areas of 20+ mph surface winds from afternoon onward, especially from southern and central Nevada northwestward through the lee of the Sierras. While critical wind fields will be exceeded in a few areas, RH values will be borderline critical based on latest forecast guidance. Furthermore, areas of thunderstorm development should also temper boundary-layer RH values in a few areas, with any critical fire weather conditions being brief and localized. Fuels are dry, however, and fire spread may occur with any ongoing fires especially where critical thresholds can be met for any length of time. ...Much of Oregon, far northern California, northern/central Nevada, and western Idaho for thunderstorms... Isolated to scattered thunderstorms are expected to develop from afternoon onward and should move north fairly quickly (25-35 kts) given the enhanced mid-level wind fields across the region. Cores should be wetter than in the previous day, however, given higher tropospheric moisture content and greater lift/ascent associated with the approach of the mid-level trough. Still, scattered, northward-moving clusters of storms should be most concentrated across southern/central Oregon and northeast Nevada/southwest Idaho and will be capable of isolated dry lightning strikes that will cause a few fire starts given dry fuels. ..Cook.. 08/08/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0142 AM CDT Thu Aug 08 2019 Valid 091200Z - 101200Z ...Synopsis... The overall synoptic pattern should remain similar throughout the D2/Thu forecast period. A longwave trough will begin to make eastward progression toward Oregon and northern California, resulting in strengthening mid-level flow from Nevada northward through western Idaho as a mid-level ridge keeps hold over the central Rockies and vicinity. Lift from the approaching trough and maintenance of mid-level moisture should promote a few thunderstorms during the afternoon and evening, while strengthening wind fields will result in elevated to locally critical fire weather in the western Great Basin. ...Much of Nevada and far northeastern California for dry/windy conditions... Vertical mixing processes beneath strengthening flow aloft and a strengthening surface trough across the region will result in areas of 20+ mph surface winds from afternoon onward, especially from southern and central Nevada northwestward through the lee of the Sierras. While critical wind fields will be exceeded in a few areas, RH values will be borderline critical based on latest forecast guidance. Furthermore, areas of thunderstorm development should also temper boundary-layer RH values in a few areas, with any critical fire weather conditions being brief and localized. Fuels are dry, however, and fire spread may occur with any ongoing fires especially where critical thresholds can be met for any length of time. ...Much of Oregon, far northern California, northern/central Nevada, and western Idaho for thunderstorms... Isolated to scattered thunderstorms are expected to develop from afternoon onward and should move north fairly quickly (25-35 kts) given the enhanced mid-level wind fields across the region. Cores should be wetter than in the previous day, however, given higher tropospheric moisture content and greater lift/ascent associated with the approach of the mid-level trough. Still, scattered, northward-moving clusters of storms should be most concentrated across southern/central Oregon and northeast Nevada/southwest Idaho and will be capable of isolated dry lightning strikes that will cause a few fire starts given dry fuels. ..Cook.. 08/08/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0142 AM CDT Thu Aug 08 2019 Valid 091200Z - 101200Z ...Synopsis... The overall synoptic pattern should remain similar throughout the D2/Thu forecast period. A longwave trough will begin to make eastward progression toward Oregon and northern California, resulting in strengthening mid-level flow from Nevada northward through western Idaho as a mid-level ridge keeps hold over the central Rockies and vicinity. Lift from the approaching trough and maintenance of mid-level moisture should promote a few thunderstorms during the afternoon and evening, while strengthening wind fields will result in elevated to locally critical fire weather in the western Great Basin. ...Much of Nevada and far northeastern California for dry/windy conditions... Vertical mixing processes beneath strengthening flow aloft and a strengthening surface trough across the region will result in areas of 20+ mph surface winds from afternoon onward, especially from southern and central Nevada northwestward through the lee of the Sierras. While critical wind fields will be exceeded in a few areas, RH values will be borderline critical based on latest forecast guidance. Furthermore, areas of thunderstorm development should also temper boundary-layer RH values in a few areas, with any critical fire weather conditions being brief and localized. Fuels are dry, however, and fire spread may occur with any ongoing fires especially where critical thresholds can be met for any length of time. ...Much of Oregon, far northern California, northern/central Nevada, and western Idaho for thunderstorms... Isolated to scattered thunderstorms are expected to develop from afternoon onward and should move north fairly quickly (25-35 kts) given the enhanced mid-level wind fields across the region. Cores should be wetter than in the previous day, however, given higher tropospheric moisture content and greater lift/ascent associated with the approach of the mid-level trough. Still, scattered, northward-moving clusters of storms should be most concentrated across southern/central Oregon and northeast Nevada/southwest Idaho and will be capable of isolated dry lightning strikes that will cause a few fire starts given dry fuels. ..Cook.. 08/08/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0142 AM CDT Thu Aug 08 2019 Valid 091200Z - 101200Z ...Synopsis... The overall synoptic pattern should remain similar throughout the D2/Thu forecast period. A longwave trough will begin to make eastward progression toward Oregon and northern California, resulting in strengthening mid-level flow from Nevada northward through western Idaho as a mid-level ridge keeps hold over the central Rockies and vicinity. Lift from the approaching trough and maintenance of mid-level moisture should promote a few thunderstorms during the afternoon and evening, while strengthening wind fields will result in elevated to locally critical fire weather in the western Great Basin. ...Much of Nevada and far northeastern California for dry/windy conditions... Vertical mixing processes beneath strengthening flow aloft and a strengthening surface trough across the region will result in areas of 20+ mph surface winds from afternoon onward, especially from southern and central Nevada northwestward through the lee of the Sierras. While critical wind fields will be exceeded in a few areas, RH values will be borderline critical based on latest forecast guidance. Furthermore, areas of thunderstorm development should also temper boundary-layer RH values in a few areas, with any critical fire weather conditions being brief and localized. Fuels are dry, however, and fire spread may occur with any ongoing fires especially where critical thresholds can be met for any length of time. ...Much of Oregon, far northern California, northern/central Nevada, and western Idaho for thunderstorms... Isolated to scattered thunderstorms are expected to develop from afternoon onward and should move north fairly quickly (25-35 kts) given the enhanced mid-level wind fields across the region. Cores should be wetter than in the previous day, however, given higher tropospheric moisture content and greater lift/ascent associated with the approach of the mid-level trough. Still, scattered, northward-moving clusters of storms should be most concentrated across southern/central Oregon and northeast Nevada/southwest Idaho and will be capable of isolated dry lightning strikes that will cause a few fire starts given dry fuels. ..Cook.. 08/08/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0110 AM CDT Thu Aug 08 2019 Valid 081200Z - 091200Z ...Synopsis... Deep southerly flow between a longwave trough over the northeastern Pacific and a longwave ridge centered over the Great Basin will maintain mid-level moisture in a corridor from Nevada northward to northern Washington State today. Heating beneath this moist plume will promote areas of isolated to scattered thunderstorms, which will serve as the main focus for fire weather threats across the West. ...Nevada, Idaho, southwestern Montana, central and eastern Oregon, and central and eastern Washington State... The aforementioned synoptic pattern and surface heating will foster development and gradual expansion of convective coverage - likely beginning around mid-morning across Nevada and expanding northward through the afternoon and evening. These storms will occur atop widespread areas of dry fuels, favoring lightning-related fire ignition and spread. Additionally, gusty/erratic downburst winds will complicate fire suppression efforts near ongoing fires in the region. The greatest coverage of storms is expected to occur across portions of Nevada during the afternoon, where 40%+ coverage of lightning strikes are expected. The primary limiting factor for a greater fire-weather threat in this area will be wetting thunderstorm cores and the likelihood of upscale growth of convection into bands/linear segments. The wetting rainfall should keep dry lightning relatively isolated in this area. Likewise, slow-moving convection across Idaho/southwestern Montana should also limit the extent of dry lightning and also result in heavy rainfall in localized areas. The extent of isolated dry lightning strikes will eventually reach Washington State later in the day (late afternoon through early evening). ..Cook.. 08/08/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0110 AM CDT Thu Aug 08 2019 Valid 081200Z - 091200Z ...Synopsis... Deep southerly flow between a longwave trough over the northeastern Pacific and a longwave ridge centered over the Great Basin will maintain mid-level moisture in a corridor from Nevada northward to northern Washington State today. Heating beneath this moist plume will promote areas of isolated to scattered thunderstorms, which will serve as the main focus for fire weather threats across the West. ...Nevada, Idaho, southwestern Montana, central and eastern Oregon, and central and eastern Washington State... The aforementioned synoptic pattern and surface heating will foster development and gradual expansion of convective coverage - likely beginning around mid-morning across Nevada and expanding northward through the afternoon and evening. These storms will occur atop widespread areas of dry fuels, favoring lightning-related fire ignition and spread. Additionally, gusty/erratic downburst winds will complicate fire suppression efforts near ongoing fires in the region. The greatest coverage of storms is expected to occur across portions of Nevada during the afternoon, where 40%+ coverage of lightning strikes are expected. The primary limiting factor for a greater fire-weather threat in this area will be wetting thunderstorm cores and the likelihood of upscale growth of convection into bands/linear segments. The wetting rainfall should keep dry lightning relatively isolated in this area. Likewise, slow-moving convection across Idaho/southwestern Montana should also limit the extent of dry lightning and also result in heavy rainfall in localized areas. The extent of isolated dry lightning strikes will eventually reach Washington State later in the day (late afternoon through early evening). ..Cook.. 08/08/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0110 AM CDT Thu Aug 08 2019 Valid 081200Z - 091200Z ...Synopsis... Deep southerly flow between a longwave trough over the northeastern Pacific and a longwave ridge centered over the Great Basin will maintain mid-level moisture in a corridor from Nevada northward to northern Washington State today. Heating beneath this moist plume will promote areas of isolated to scattered thunderstorms, which will serve as the main focus for fire weather threats across the West. ...Nevada, Idaho, southwestern Montana, central and eastern Oregon, and central and eastern Washington State... The aforementioned synoptic pattern and surface heating will foster development and gradual expansion of convective coverage - likely beginning around mid-morning across Nevada and expanding northward through the afternoon and evening. These storms will occur atop widespread areas of dry fuels, favoring lightning-related fire ignition and spread. Additionally, gusty/erratic downburst winds will complicate fire suppression efforts near ongoing fires in the region. The greatest coverage of storms is expected to occur across portions of Nevada during the afternoon, where 40%+ coverage of lightning strikes are expected. The primary limiting factor for a greater fire-weather threat in this area will be wetting thunderstorm cores and the likelihood of upscale growth of convection into bands/linear segments. The wetting rainfall should keep dry lightning relatively isolated in this area. Likewise, slow-moving convection across Idaho/southwestern Montana should also limit the extent of dry lightning and also result in heavy rainfall in localized areas. The extent of isolated dry lightning strikes will eventually reach Washington State later in the day (late afternoon through early evening). ..Cook.. 08/08/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0110 AM CDT Thu Aug 08 2019 Valid 081200Z - 091200Z ...Synopsis... Deep southerly flow between a longwave trough over the northeastern Pacific and a longwave ridge centered over the Great Basin will maintain mid-level moisture in a corridor from Nevada northward to northern Washington State today. Heating beneath this moist plume will promote areas of isolated to scattered thunderstorms, which will serve as the main focus for fire weather threats across the West. ...Nevada, Idaho, southwestern Montana, central and eastern Oregon, and central and eastern Washington State... The aforementioned synoptic pattern and surface heating will foster development and gradual expansion of convective coverage - likely beginning around mid-morning across Nevada and expanding northward through the afternoon and evening. These storms will occur atop widespread areas of dry fuels, favoring lightning-related fire ignition and spread. Additionally, gusty/erratic downburst winds will complicate fire suppression efforts near ongoing fires in the region. The greatest coverage of storms is expected to occur across portions of Nevada during the afternoon, where 40%+ coverage of lightning strikes are expected. The primary limiting factor for a greater fire-weather threat in this area will be wetting thunderstorm cores and the likelihood of upscale growth of convection into bands/linear segments. The wetting rainfall should keep dry lightning relatively isolated in this area. Likewise, slow-moving convection across Idaho/southwestern Montana should also limit the extent of dry lightning and also result in heavy rainfall in localized areas. The extent of isolated dry lightning strikes will eventually reach Washington State later in the day (late afternoon through early evening). ..Cook.. 08/08/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 1673 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR KANSAS
Mesoscale Discussion 1673 NWS Storm Prediction Center Norman OK 0101 AM CDT Thu Aug 08 2019 Areas affected...Kansas Concerning...Severe potential...Watch unlikely Valid 080601Z - 080830Z Probability of Watch Issuance...20 percent SUMMARY...A potential for hail and marginally severe wind gusts will exist tonight along a west-northwest to east-southeast corridor from northwest to southeast Kansas. Although weather watch issuance appears unlikely, the situation will continue to be monitored. DISCUSSION...The latest surface analysis shows a quasi-stationary front located from southwest Kansas into northern Oklahoma. An axis of moderate instability is analyzed by the RAP to the north of the front where MLCAPE is peaked in the 2,000 to 2,500 J/kg range. A cluster of strong thunderstorms is located near the Colorado-Kansas line just to the west of the strongest instability. These storms will continue to move eastward into the instability maximum over the next few hours helping to sustain updraft intensity. The Goodland WSR-88D VWP has about 30 kt of deep-layer shear. This combined with mid-level lapse rates around 8.0 C/km (evident on the RAP analysis) should support hail with the stronger updrafts. Marginally severe wind gusts will also be possible along the leading edge of the MCS. Further to the southeast across central and southeastern Kansas, MLCIN is substantially stronger. For this reason, the convection will remain be elevated in nature tonight. Even so, instability aloft and effective shear around 30 kt as estimated by the RAP and evident on regional WSR-88D VWPs should support a marginal hail threat. ..Broyles/Edwards.. 08/08/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...SGF...TOP...ICT...GID...DDC...GLD... LAT...LON 39609890 38479607 37729509 37379493 37129508 37019540 37109607 37479677 38079797 38709973 38990092 39100165 39530190 39900150 40030056 39609890 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Thu Aug 08 2019 Valid 091200Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF CENTRAL OREGON AND OVER WESTERN PORTIONS OF THE NORTHERN PLAINS... ...SUMMARY... Strong to severe thunderstorms are possible across portions of the northern Plains, as well as parts of central Oregon, Friday afternoon and evening. Large hail and damaging wind gusts will be the main concern. ...Central Oregon Vicinity... South/southwesterly deep layer flow will strengthen on Friday as an upper low pivots eastward over northern CA and OR. This deep-layer southerly flow will bring monsoonal moisture northward into the region, and surface dewpoints climbing into the low to mid 50s are possible. As heights fall and temperatures aloft cool, steep midlevel lapse rates will overspread the region, while strong surface heating results in scattered thunderstorm development during the afternoon. MLCAPE values will generally range from 500-1000 J/kg and effective shear greater than 35 kt is forecast. This should result in organized cells with rotating updrafts capable of large hail. Additionally, where deep boundary-layer mixing occurs, inverted-v sub-cloud thermodynamic profiles suggest cells also will pose a locally damaging wind threat. While not expected to be the main threat, guidance does suggest there could be a threat for a weak/brief tornado over central OR as a southeastward-progressing cold front moves toward the area after 00z. Any cells interacting with the boundary could result in lowered LCLs and enhanced SRH. However, this threat appears rather conditional and uncertain. ...Northern Plains into the Central High Plains Vicinity... The upper ridge will continue to be oriented from central TX north/northwest into MT on Friday. A couple of shortwave impulses are forecast to migrate through the ridge, providing support for strong to severe storms. The first, and stronger impulse, will eject eastward from the northern Rockies into the northern Plains. This should allow suppression of the upper ridge and associated midlevel capping through increased forcing for ascent, as boundary-layer moisture increases on strengthening low-level southeasterly flow. A weak low/surface trough will extend from eastern MT into western SD and thunderstorms are expected to develop during the afternoon along this boundary and shift east through the evening. Midlevel lapse rates will be unimpressive across the region due to warm temperatures aloft under the influence of the upper ridge, but strong heating and surface dewpoints in the 60s will result in moderate to strong instability (MLCAPE 2000-3500) in the presence of supercell vertical wind profiles. In fact, long, straight forecast hodographs indicate potential for storms dominated by hail production. Additionally, steep low-level lapse rates will support locally damaging winds as well. Some guidance suggest some upscale growth is possible as a 40 kt southerly low level jet develops during the evening across central NE/SD. If this occurs, a damaging wind threat could develop and probabilities may need adjusted in subsequent outlooks. More subtle monsoon-related impulses will float across the central Rockies and trigger thunderstorms over higher terrain during the afternoon. While deep-layer flow is weaker compared to further north, effective shear around 40 kt and steep lapse rates in the presence of 2000-3000 J/kg MLCAPE should maintain storms eastward over the adjacent High Plains. Isolated large hail and strong wind gusts will be the main concern with this convection. ...Ozarks into northern MS and western TN... Guidance continues to suggest that a likely MCV will progress east/southeast from the Ozarks into northern MS. A very moist and unstable downstream airmass will support strong to severe storms, with damaging winds being the main concern, aided by PW values greater than 2 inches and effective shear greater than 25 kt. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% - Slight ..Leitman.. 08/08/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Thu Aug 08 2019 Valid 091200Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF CENTRAL OREGON AND OVER WESTERN PORTIONS OF THE NORTHERN PLAINS... ...SUMMARY... Strong to severe thunderstorms are possible across portions of the northern Plains, as well as parts of central Oregon, Friday afternoon and evening. Large hail and damaging wind gusts will be the main concern. ...Central Oregon Vicinity... South/southwesterly deep layer flow will strengthen on Friday as an upper low pivots eastward over northern CA and OR. This deep-layer southerly flow will bring monsoonal moisture northward into the region, and surface dewpoints climbing into the low to mid 50s are possible. As heights fall and temperatures aloft cool, steep midlevel lapse rates will overspread the region, while strong surface heating results in scattered thunderstorm development during the afternoon. MLCAPE values will generally range from 500-1000 J/kg and effective shear greater than 35 kt is forecast. This should result in organized cells with rotating updrafts capable of large hail. Additionally, where deep boundary-layer mixing occurs, inverted-v sub-cloud thermodynamic profiles suggest cells also will pose a locally damaging wind threat. While not expected to be the main threat, guidance does suggest there could be a threat for a weak/brief tornado over central OR as a southeastward-progressing cold front moves toward the area after 00z. Any cells interacting with the boundary could result in lowered LCLs and enhanced SRH. However, this threat appears rather conditional and uncertain. ...Northern Plains into the Central High Plains Vicinity... The upper ridge will continue to be oriented from central TX north/northwest into MT on Friday. A couple of shortwave impulses are forecast to migrate through the ridge, providing support for strong to severe storms. The first, and stronger impulse, will eject eastward from the northern Rockies into the northern Plains. This should allow suppression of the upper ridge and associated midlevel capping through increased forcing for ascent, as boundary-layer moisture increases on strengthening low-level southeasterly flow. A weak low/surface trough will extend from eastern MT into western SD and thunderstorms are expected to develop during the afternoon along this boundary and shift east through the evening. Midlevel lapse rates will be unimpressive across the region due to warm temperatures aloft under the influence of the upper ridge, but strong heating and surface dewpoints in the 60s will result in moderate to strong instability (MLCAPE 2000-3500) in the presence of supercell vertical wind profiles. In fact, long, straight forecast hodographs indicate potential for storms dominated by hail production. Additionally, steep low-level lapse rates will support locally damaging winds as well. Some guidance suggest some upscale growth is possible as a 40 kt southerly low level jet develops during the evening across central NE/SD. If this occurs, a damaging wind threat could develop and probabilities may need adjusted in subsequent outlooks. More subtle monsoon-related impulses will float across the central Rockies and trigger thunderstorms over higher terrain during the afternoon. While deep-layer flow is weaker compared to further north, effective shear around 40 kt and steep lapse rates in the presence of 2000-3000 J/kg MLCAPE should maintain storms eastward over the adjacent High Plains. Isolated large hail and strong wind gusts will be the main concern with this convection. ...Ozarks into northern MS and western TN... Guidance continues to suggest that a likely MCV will progress east/southeast from the Ozarks into northern MS. A very moist and unstable downstream airmass will support strong to severe storms, with damaging winds being the main concern, aided by PW values greater than 2 inches and effective shear greater than 25 kt. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% - Slight ..Leitman.. 08/08/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Thu Aug 08 2019 Valid 091200Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF CENTRAL OREGON AND OVER WESTERN PORTIONS OF THE NORTHERN PLAINS... ...SUMMARY... Strong to severe thunderstorms are possible across portions of the northern Plains, as well as parts of central Oregon, Friday afternoon and evening. Large hail and damaging wind gusts will be the main concern. ...Central Oregon Vicinity... South/southwesterly deep layer flow will strengthen on Friday as an upper low pivots eastward over northern CA and OR. This deep-layer southerly flow will bring monsoonal moisture northward into the region, and surface dewpoints climbing into the low to mid 50s are possible. As heights fall and temperatures aloft cool, steep midlevel lapse rates will overspread the region, while strong surface heating results in scattered thunderstorm development during the afternoon. MLCAPE values will generally range from 500-1000 J/kg and effective shear greater than 35 kt is forecast. This should result in organized cells with rotating updrafts capable of large hail. Additionally, where deep boundary-layer mixing occurs, inverted-v sub-cloud thermodynamic profiles suggest cells also will pose a locally damaging wind threat. While not expected to be the main threat, guidance does suggest there could be a threat for a weak/brief tornado over central OR as a southeastward-progressing cold front moves toward the area after 00z. Any cells interacting with the boundary could result in lowered LCLs and enhanced SRH. However, this threat appears rather conditional and uncertain. ...Northern Plains into the Central High Plains Vicinity... The upper ridge will continue to be oriented from central TX north/northwest into MT on Friday. A couple of shortwave impulses are forecast to migrate through the ridge, providing support for strong to severe storms. The first, and stronger impulse, will eject eastward from the northern Rockies into the northern Plains. This should allow suppression of the upper ridge and associated midlevel capping through increased forcing for ascent, as boundary-layer moisture increases on strengthening low-level southeasterly flow. A weak low/surface trough will extend from eastern MT into western SD and thunderstorms are expected to develop during the afternoon along this boundary and shift east through the evening. Midlevel lapse rates will be unimpressive across the region due to warm temperatures aloft under the influence of the upper ridge, but strong heating and surface dewpoints in the 60s will result in moderate to strong instability (MLCAPE 2000-3500) in the presence of supercell vertical wind profiles. In fact, long, straight forecast hodographs indicate potential for storms dominated by hail production. Additionally, steep low-level lapse rates will support locally damaging winds as well. Some guidance suggest some upscale growth is possible as a 40 kt southerly low level jet develops during the evening across central NE/SD. If this occurs, a damaging wind threat could develop and probabilities may need adjusted in subsequent outlooks. More subtle monsoon-related impulses will float across the central Rockies and trigger thunderstorms over higher terrain during the afternoon. While deep-layer flow is weaker compared to further north, effective shear around 40 kt and steep lapse rates in the presence of 2000-3000 J/kg MLCAPE should maintain storms eastward over the adjacent High Plains. Isolated large hail and strong wind gusts will be the main concern with this convection. ...Ozarks into northern MS and western TN... Guidance continues to suggest that a likely MCV will progress east/southeast from the Ozarks into northern MS. A very moist and unstable downstream airmass will support strong to severe storms, with damaging winds being the main concern, aided by PW values greater than 2 inches and effective shear greater than 25 kt. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% - Slight ..Leitman.. 08/08/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Thu Aug 08 2019 Valid 091200Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF CENTRAL OREGON AND OVER WESTERN PORTIONS OF THE NORTHERN PLAINS... ...SUMMARY... Strong to severe thunderstorms are possible across portions of the northern Plains, as well as parts of central Oregon, Friday afternoon and evening. Large hail and damaging wind gusts will be the main concern. ...Central Oregon Vicinity... South/southwesterly deep layer flow will strengthen on Friday as an upper low pivots eastward over northern CA and OR. This deep-layer southerly flow will bring monsoonal moisture northward into the region, and surface dewpoints climbing into the low to mid 50s are possible. As heights fall and temperatures aloft cool, steep midlevel lapse rates will overspread the region, while strong surface heating results in scattered thunderstorm development during the afternoon. MLCAPE values will generally range from 500-1000 J/kg and effective shear greater than 35 kt is forecast. This should result in organized cells with rotating updrafts capable of large hail. Additionally, where deep boundary-layer mixing occurs, inverted-v sub-cloud thermodynamic profiles suggest cells also will pose a locally damaging wind threat. While not expected to be the main threat, guidance does suggest there could be a threat for a weak/brief tornado over central OR as a southeastward-progressing cold front moves toward the area after 00z. Any cells interacting with the boundary could result in lowered LCLs and enhanced SRH. However, this threat appears rather conditional and uncertain. ...Northern Plains into the Central High Plains Vicinity... The upper ridge will continue to be oriented from central TX north/northwest into MT on Friday. A couple of shortwave impulses are forecast to migrate through the ridge, providing support for strong to severe storms. The first, and stronger impulse, will eject eastward from the northern Rockies into the northern Plains. This should allow suppression of the upper ridge and associated midlevel capping through increased forcing for ascent, as boundary-layer moisture increases on strengthening low-level southeasterly flow. A weak low/surface trough will extend from eastern MT into western SD and thunderstorms are expected to develop during the afternoon along this boundary and shift east through the evening. Midlevel lapse rates will be unimpressive across the region due to warm temperatures aloft under the influence of the upper ridge, but strong heating and surface dewpoints in the 60s will result in moderate to strong instability (MLCAPE 2000-3500) in the presence of supercell vertical wind profiles. In fact, long, straight forecast hodographs indicate potential for storms dominated by hail production. Additionally, steep low-level lapse rates will support locally damaging winds as well. Some guidance suggest some upscale growth is possible as a 40 kt southerly low level jet develops during the evening across central NE/SD. If this occurs, a damaging wind threat could develop and probabilities may need adjusted in subsequent outlooks. More subtle monsoon-related impulses will float across the central Rockies and trigger thunderstorms over higher terrain during the afternoon. While deep-layer flow is weaker compared to further north, effective shear around 40 kt and steep lapse rates in the presence of 2000-3000 J/kg MLCAPE should maintain storms eastward over the adjacent High Plains. Isolated large hail and strong wind gusts will be the main concern with this convection. ...Ozarks into northern MS and western TN... Guidance continues to suggest that a likely MCV will progress east/southeast from the Ozarks into northern MS. A very moist and unstable downstream airmass will support strong to severe storms, with damaging winds being the main concern, aided by PW values greater than 2 inches and effective shear greater than 25 kt. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% - Slight ..Leitman.. 08/08/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1148 PM CDT Wed Aug 07 2019 Valid 081200Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OHIO VALLEY INTO CENTRAL NEW YORK AND PENNSYLVANIA... ...SUMMARY... Areas of hail and strong wind gusts are likely from the Ohio Valley eastward into central New York and Pennsylvania. Isolated severe hail is possible across parts of the High Plains. ...Synopsis... A broad area of cyclonic flow aloft will stretch from the upper MS Valley across the Great Lakes and the Northeast. A leading wave will move across New England during the day, with a secondary stronger wave moving into western NY and PA by 00Z. A cold front will progress across Lakes Ontario and Erie by 18Z, and will trail westward across central OH and IN. Ahead of the front, widespread low to mid 60s F dewpoints will exist beneath cool profiles aloft supporting strong to locally severe storms. To the west, an upper ridge will exist over the Rockies, with northwest flow over the Plains. A weak area of low pressure will exist over the TX Panhandle and western OK, with a stationary front extending eastward over northern OK or near the KS border. Ample low-level moisture will exist over the central Plains, with easterly winds north of the front aiding destabilization across the High Plains late in the day. ...OH Valley into the Northeast... An arcing line of storms is likely to develop by 18Z from western NY into northwest PA along the cold front, with additional development westward into OH and IN later in the afternoon. Northwest flow aloft will have a large component perpendicular to the boundary, with strong winds in the upper levels. This suggests the dominant storm mode will be cellular, with large hail likely. Little low-level shear/SRH suggests very low tornado risk, though damaging winds will be possible as storms form during peak heating with steep boundary layer lapse rates and 25-30 kt westerly 850 mb winds. ...Central and northern High Plains and northern Oklahoma into southern Kansas... Strong heating will occur beneath the upper ridge, while easterly surface winds maintain 50s dewpoints into eastern WY and CO. This will support afternoon development over the higher terrain, with activity slowly moving eastward through evening. Weak low-level winds beneath modest mid to upper flow will support a few slow-moving cells or propagating outflows, with marginal hail or wind will be possible. To the east into OK and KS, convection is likely to be ongoing early in the day north of the front from KS into western MO in a warm advection regime. Heating will occur upstream across TX and OK, resulting in areas of strong instability. New development is likely during the late afternoon and evening along the east-west front, with locally severe wind gusts or hail possible. ..Jewell/Cook.. 08/08/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1148 PM CDT Wed Aug 07 2019 Valid 081200Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OHIO VALLEY INTO CENTRAL NEW YORK AND PENNSYLVANIA... ...SUMMARY... Areas of hail and strong wind gusts are likely from the Ohio Valley eastward into central New York and Pennsylvania. Isolated severe hail is possible across parts of the High Plains. ...Synopsis... A broad area of cyclonic flow aloft will stretch from the upper MS Valley across the Great Lakes and the Northeast. A leading wave will move across New England during the day, with a secondary stronger wave moving into western NY and PA by 00Z. A cold front will progress across Lakes Ontario and Erie by 18Z, and will trail westward across central OH and IN. Ahead of the front, widespread low to mid 60s F dewpoints will exist beneath cool profiles aloft supporting strong to locally severe storms. To the west, an upper ridge will exist over the Rockies, with northwest flow over the Plains. A weak area of low pressure will exist over the TX Panhandle and western OK, with a stationary front extending eastward over northern OK or near the KS border. Ample low-level moisture will exist over the central Plains, with easterly winds north of the front aiding destabilization across the High Plains late in the day. ...OH Valley into the Northeast... An arcing line of storms is likely to develop by 18Z from western NY into northwest PA along the cold front, with additional development westward into OH and IN later in the afternoon. Northwest flow aloft will have a large component perpendicular to the boundary, with strong winds in the upper levels. This suggests the dominant storm mode will be cellular, with large hail likely. Little low-level shear/SRH suggests very low tornado risk, though damaging winds will be possible as storms form during peak heating with steep boundary layer lapse rates and 25-30 kt westerly 850 mb winds. ...Central and northern High Plains and northern Oklahoma into southern Kansas... Strong heating will occur beneath the upper ridge, while easterly surface winds maintain 50s dewpoints into eastern WY and CO. This will support afternoon development over the higher terrain, with activity slowly moving eastward through evening. Weak low-level winds beneath modest mid to upper flow will support a few slow-moving cells or propagating outflows, with marginal hail or wind will be possible. To the east into OK and KS, convection is likely to be ongoing early in the day north of the front from KS into western MO in a warm advection regime. Heating will occur upstream across TX and OK, resulting in areas of strong instability. New development is likely during the late afternoon and evening along the east-west front, with locally severe wind gusts or hail possible. ..Jewell/Cook.. 08/08/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1148 PM CDT Wed Aug 07 2019 Valid 081200Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OHIO VALLEY INTO CENTRAL NEW YORK AND PENNSYLVANIA... ...SUMMARY... Areas of hail and strong wind gusts are likely from the Ohio Valley eastward into central New York and Pennsylvania. Isolated severe hail is possible across parts of the High Plains. ...Synopsis... A broad area of cyclonic flow aloft will stretch from the upper MS Valley across the Great Lakes and the Northeast. A leading wave will move across New England during the day, with a secondary stronger wave moving into western NY and PA by 00Z. A cold front will progress across Lakes Ontario and Erie by 18Z, and will trail westward across central OH and IN. Ahead of the front, widespread low to mid 60s F dewpoints will exist beneath cool profiles aloft supporting strong to locally severe storms. To the west, an upper ridge will exist over the Rockies, with northwest flow over the Plains. A weak area of low pressure will exist over the TX Panhandle and western OK, with a stationary front extending eastward over northern OK or near the KS border. Ample low-level moisture will exist over the central Plains, with easterly winds north of the front aiding destabilization across the High Plains late in the day. ...OH Valley into the Northeast... An arcing line of storms is likely to develop by 18Z from western NY into northwest PA along the cold front, with additional development westward into OH and IN later in the afternoon. Northwest flow aloft will have a large component perpendicular to the boundary, with strong winds in the upper levels. This suggests the dominant storm mode will be cellular, with large hail likely. Little low-level shear/SRH suggests very low tornado risk, though damaging winds will be possible as storms form during peak heating with steep boundary layer lapse rates and 25-30 kt westerly 850 mb winds. ...Central and northern High Plains and northern Oklahoma into southern Kansas... Strong heating will occur beneath the upper ridge, while easterly surface winds maintain 50s dewpoints into eastern WY and CO. This will support afternoon development over the higher terrain, with activity slowly moving eastward through evening. Weak low-level winds beneath modest mid to upper flow will support a few slow-moving cells or propagating outflows, with marginal hail or wind will be possible. To the east into OK and KS, convection is likely to be ongoing early in the day north of the front from KS into western MO in a warm advection regime. Heating will occur upstream across TX and OK, resulting in areas of strong instability. New development is likely during the late afternoon and evening along the east-west front, with locally severe wind gusts or hail possible. ..Jewell/Cook.. 08/08/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1148 PM CDT Wed Aug 07 2019 Valid 081200Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OHIO VALLEY INTO CENTRAL NEW YORK AND PENNSYLVANIA... ...SUMMARY... Areas of hail and strong wind gusts are likely from the Ohio Valley eastward into central New York and Pennsylvania. Isolated severe hail is possible across parts of the High Plains. ...Synopsis... A broad area of cyclonic flow aloft will stretch from the upper MS Valley across the Great Lakes and the Northeast. A leading wave will move across New England during the day, with a secondary stronger wave moving into western NY and PA by 00Z. A cold front will progress across Lakes Ontario and Erie by 18Z, and will trail westward across central OH and IN. Ahead of the front, widespread low to mid 60s F dewpoints will exist beneath cool profiles aloft supporting strong to locally severe storms. To the west, an upper ridge will exist over the Rockies, with northwest flow over the Plains. A weak area of low pressure will exist over the TX Panhandle and western OK, with a stationary front extending eastward over northern OK or near the KS border. Ample low-level moisture will exist over the central Plains, with easterly winds north of the front aiding destabilization across the High Plains late in the day. ...OH Valley into the Northeast... An arcing line of storms is likely to develop by 18Z from western NY into northwest PA along the cold front, with additional development westward into OH and IN later in the afternoon. Northwest flow aloft will have a large component perpendicular to the boundary, with strong winds in the upper levels. This suggests the dominant storm mode will be cellular, with large hail likely. Little low-level shear/SRH suggests very low tornado risk, though damaging winds will be possible as storms form during peak heating with steep boundary layer lapse rates and 25-30 kt westerly 850 mb winds. ...Central and northern High Plains and northern Oklahoma into southern Kansas... Strong heating will occur beneath the upper ridge, while easterly surface winds maintain 50s dewpoints into eastern WY and CO. This will support afternoon development over the higher terrain, with activity slowly moving eastward through evening. Weak low-level winds beneath modest mid to upper flow will support a few slow-moving cells or propagating outflows, with marginal hail or wind will be possible. To the east into OK and KS, convection is likely to be ongoing early in the day north of the front from KS into western MO in a warm advection regime. Heating will occur upstream across TX and OK, resulting in areas of strong instability. New development is likely during the late afternoon and evening along the east-west front, with locally severe wind gusts or hail possible. ..Jewell/Cook.. 08/08/2019 Read more

MD 1672 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR SOUTHERN SD...NORTHERN NE
Mesoscale Discussion 1672 NWS Storm Prediction Center Norman OK 1113 PM CDT Wed Aug 07 2019 Areas affected...Southern SD...Northern NE Concerning...Severe potential...Watch unlikely Valid 080413Z - 080545Z Probability of Watch Issuance...20 percent SUMMARY...Some hail threat, along with gusty winds, are possible with storms along the SD/NE border region for the next several hours. Severe thunderstorm watch is not anticipated. DISCUSSION...Weak warm advection appears mostly responsible for recent elevated convection along the SD/NE border. This activity is developing just north of a weak front that is sagging slowly south across the central Plains. Forecast soundings across the central Plains exhibit more than adequate cloud-layer shear for sustained updrafts; however, forecast hail algorithm is not particularly aggressive with with values generally on the order of 1" or less. Even so, hail likely accompanies more organized supercells. Will continue to monitor this region but it remains unclear whether this activity will achieve sustained severe levels warranting a severe thunderstorm watch. ..Darrow/Hart.. 08/08/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FSD...OAX...LBF...UNR... LAT...LON 43560014 42829688 42059777 42700072 43180136 43560014 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0800 PM CDT Wed Aug 07 2019 Valid 080100Z - 081200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS... ...SUMMARY... Scattered storms are expected tonight across parts of the Central Plains, with hail or wind possible. Otherwise, a decreasing severe threat is expected across the Great Lakes, Mid Atlantic, and Lower Mississippi Valley where isolated strong wind gusts remain possible. ...Central Plains... A moist and unstable air mass remains over much of the central states, with sporadic storms across many states. One possible corridor of focused severe threat is expected to develop along and north of a stationary front extending from eastern CO across KS and into southwest MO. Southwesterly 850 mb winds are expected to increase tonight, which will increase warm advection near this boundary. The steep lapse rate environment beneath modest northwest flow aloft should support scattered storms in a northwest-southeast zone along the front, with hail and locally damaging wind gusts possible. ...WI.. Cooler and drier air will continue to surge across WI behind a cold front, and will continue to support scattered thunderstorms. The instability axis currently extends northeastward out of IA and into WI, and this is where isolated marginally severe storms are possible. A weakening trend is expected with the loss of heating, thus the threat may only exist for a couple hours. ..Jewell.. 08/08/2019 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0800 PM CDT Wed Aug 07 2019 Valid 080100Z - 081200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS... ...SUMMARY... Scattered storms are expected tonight across parts of the Central Plains, with hail or wind possible. Otherwise, a decreasing severe threat is expected across the Great Lakes, Mid Atlantic, and Lower Mississippi Valley where isolated strong wind gusts remain possible. ...Central Plains... A moist and unstable air mass remains over much of the central states, with sporadic storms across many states. One possible corridor of focused severe threat is expected to develop along and north of a stationary front extending from eastern CO across KS and into southwest MO. Southwesterly 850 mb winds are expected to increase tonight, which will increase warm advection near this boundary. The steep lapse rate environment beneath modest northwest flow aloft should support scattered storms in a northwest-southeast zone along the front, with hail and locally damaging wind gusts possible. ...WI.. Cooler and drier air will continue to surge across WI behind a cold front, and will continue to support scattered thunderstorms. The instability axis currently extends northeastward out of IA and into WI, and this is where isolated marginally severe storms are possible. A weakening trend is expected with the loss of heating, thus the threat may only exist for a couple hours. ..Jewell.. 08/08/2019 Read more