Severe Storms

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook RESENT 1 NWS Storm Prediction Center Norman OK 0302 AM CDT Mon Sep 09 2019 Valid 111200Z - 121200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN PLAINS INTO THE UPPER MISSISSIPPI VALLEY... ...SUMMARY... Thunderstorms associated with large hail and damaging wind gusts are expected to develop on Wednesday from parts of the central and northern Plains eastward into the Upper Mississippi Valley. ...Central and Northern Plains/Upper Mississippi Valley... A shortwave ridge is forecast to move northeastward into the Upper Mississippi Valley on Wednesday as an upper-level trough moves across the Intermountain West. Southwest mid-level flow will be in place across the central and northern Plains as a surface low moves eastward into the central High Plains. A well-defined warm front is forecast to extend eastward from the surface low from southern South Dakota into far northern Iowa. Surface dewpoints south of the front should be in the upper 60s to near 70 F, aiding the development of an east to west axis of moderate instability by afternoon. The latest model runs continue to develop elevated convection during the day to the north of the warm front and have the strongest instability further to the west in southeastern South Dakota. The current thinking is that surface-based thunderstorms will develop in the late afternoon on the western edge of this pocket of strong instability from south-central South Dakota into north-central Nebraska. This convection should spread east-northeastward across southeastern South Dakota from late afternoon to mid evening. NAM and GFS forecast soundings to the west of Sioux Falls for early Wednesday evening continue to show a favorable environment for severe storms with strong instability, moderate deep-layer shear and steep mid-level lapse rates. This environment should support supercells with large hail. Wind damage may also occur especially if an MCS can develop during the evening as the GFS and ECMWF suggest. Although a capping inversion will limit convective development across the mid Missouri Valley, confidence is higher that a cluster of strong to severe thunderstorms will develop in southeastern South Dakota. For this reason, a 15 percent contour has been continued in that area for this outlook. ..Broyles.. 09/09/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226 AM CDT Mon Sep 09 2019 Valid 111200Z - 121200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN PLAINS INTO THE UPPER MISSISSIPPI VALLEY... ...SUMMARY... Thunderstorms associated with large hail and damaging wind gusts are expected to develop on Wednesday from parts of the central and northern Plains eastward into the Upper Mississippi Valley. ...Central and Northern Plains/Upper Mississippi Valley... A shortwave ridge is forecast to move northeastward into the Upper Mississippi Valley on Wednesday as an upper-level trough moves across the Intermountain West. Southwest mid-level flow will be in place across the central and northern Plains as a surface low moves eastward into the central High Plains. A well-defined warm front is forecast to extend eastward from the surface low from southern South Dakota into far northern Iowa. Surface dewpoints south of the front should be in the upper 60s to near 70 F, aiding the development of an east to west axis of moderate instability by afternoon. The latest model runs continue to develop elevated convection during the day to the north of the warm front and have the strongest instability further to the west in southeastern South Dakota. The current thinking is that surface-based thunderstorms will develop in the late afternoon on the western edge of this pocket of strong instability from south-central South Dakota into north-central Nebraska. This convection should spread east-northeastward across southeastern South Dakota from late afternoon to mid evening. NAM and GFS forecast soundings to the west of Sioux Falls for early Wednesday evening continue to show a favorable environment for severe storms with strong instability, moderate deep-layer shear and steep mid-level lapse rates. This environment should support supercells with large hail. Wind damage may also occur especially if an MCS can develop during the evening as the GFS and ECMWF suggest. Although a capping inversion will limit convective development across the mid Missouri Valley, confidence is higher that a cluster of strong to severe thunderstorms will develop in southeastern South Dakota. For this reason, a 15 percent contour has been continued in that area for this outlook. ..Broyles.. 09/09/2019 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0134 AM CDT Mon Sep 09 2019 Valid 101200Z - 111200Z ...Synopsis... Broad mid/upper-level cyclonic flow is forecast to remain over the western CONUS Day 2/Tuesday. As this occurs, an area of enhanced mid-level flow -- located near the base of the trough -- is forecast to strengthen while overspreading portions of Southern California, the Southwest, and the southern Great Basin. ...Southern California: Santa Barbara and Ventura Counties... Gusty Sundowner winds are forecast to continue through Day 2/Tuesday across eastern Santa Barbara and western Ventura Counties. While minimum RH values are forecast to be a bit higher than previous days (e.g., 20-25%), elevated fire weather conditions will likely persist given the gusty winds and receptive fuels. As with previous nights, locally elevated conditions may remain overnight at higher elevations (e.g., > 1 kft) due to relatively poor RH recoveries and lingering gusty winds. ...Nevada/Utah/Arizona... While strong/gusty winds are forecast across portions of southern Nevada/Utah and northern Arizona, increasing low-level moisture should temper fire weather conditions relative to recent days. Nevertheless, locally elevated conditions are possible. ..Elliott.. 09/09/2019 ...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 0134 AM CDT Mon Sep 09 2019 Valid 101200Z - 111200Z ...Synopsis... Broad mid/upper-level cyclonic flow is forecast to remain over the western CONUS Day 2/Tuesday. As this occurs, an area of enhanced mid-level flow -- located near the base of the trough -- is forecast to strengthen while overspreading portions of Southern California, the Southwest, and the southern Great Basin. ...Southern California: Santa Barbara and Ventura Counties... Gusty Sundowner winds are forecast to continue through Day 2/Tuesday across eastern Santa Barbara and western Ventura Counties. While minimum RH values are forecast to be a bit higher than previous days (e.g., 20-25%), elevated fire weather conditions will likely persist given the gusty winds and receptive fuels. As with previous nights, locally elevated conditions may remain overnight at higher elevations (e.g., > 1 kft) due to relatively poor RH recoveries and lingering gusty winds. ...Nevada/Utah/Arizona... While strong/gusty winds are forecast across portions of southern Nevada/Utah and northern Arizona, increasing low-level moisture should temper fire weather conditions relative to recent days. Nevertheless, locally elevated conditions are possible. ..Elliott.. 09/09/2019 ...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 0134 AM CDT Mon Sep 09 2019 Valid 101200Z - 111200Z ...Synopsis... Broad mid/upper-level cyclonic flow is forecast to remain over the western CONUS Day 2/Tuesday. As this occurs, an area of enhanced mid-level flow -- located near the base of the trough -- is forecast to strengthen while overspreading portions of Southern California, the Southwest, and the southern Great Basin. ...Southern California: Santa Barbara and Ventura Counties... Gusty Sundowner winds are forecast to continue through Day 2/Tuesday across eastern Santa Barbara and western Ventura Counties. While minimum RH values are forecast to be a bit higher than previous days (e.g., 20-25%), elevated fire weather conditions will likely persist given the gusty winds and receptive fuels. As with previous nights, locally elevated conditions may remain overnight at higher elevations (e.g., > 1 kft) due to relatively poor RH recoveries and lingering gusty winds. ...Nevada/Utah/Arizona... While strong/gusty winds are forecast across portions of southern Nevada/Utah and northern Arizona, increasing low-level moisture should temper fire weather conditions relative to recent days. Nevertheless, locally elevated conditions are possible. ..Elliott.. 09/09/2019 ...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 0134 AM CDT Mon Sep 09 2019 Valid 101200Z - 111200Z ...Synopsis... Broad mid/upper-level cyclonic flow is forecast to remain over the western CONUS Day 2/Tuesday. As this occurs, an area of enhanced mid-level flow -- located near the base of the trough -- is forecast to strengthen while overspreading portions of Southern California, the Southwest, and the southern Great Basin. ...Southern California: Santa Barbara and Ventura Counties... Gusty Sundowner winds are forecast to continue through Day 2/Tuesday across eastern Santa Barbara and western Ventura Counties. While minimum RH values are forecast to be a bit higher than previous days (e.g., 20-25%), elevated fire weather conditions will likely persist given the gusty winds and receptive fuels. As with previous nights, locally elevated conditions may remain overnight at higher elevations (e.g., > 1 kft) due to relatively poor RH recoveries and lingering gusty winds. ...Nevada/Utah/Arizona... While strong/gusty winds are forecast across portions of southern Nevada/Utah and northern Arizona, increasing low-level moisture should temper fire weather conditions relative to recent days. Nevertheless, locally elevated conditions are possible. ..Elliott.. 09/09/2019 ...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 0134 AM CDT Mon Sep 09 2019 Valid 101200Z - 111200Z ...Synopsis... Broad mid/upper-level cyclonic flow is forecast to remain over the western CONUS Day 2/Tuesday. As this occurs, an area of enhanced mid-level flow -- located near the base of the trough -- is forecast to strengthen while overspreading portions of Southern California, the Southwest, and the southern Great Basin. ...Southern California: Santa Barbara and Ventura Counties... Gusty Sundowner winds are forecast to continue through Day 2/Tuesday across eastern Santa Barbara and western Ventura Counties. While minimum RH values are forecast to be a bit higher than previous days (e.g., 20-25%), elevated fire weather conditions will likely persist given the gusty winds and receptive fuels. As with previous nights, locally elevated conditions may remain overnight at higher elevations (e.g., > 1 kft) due to relatively poor RH recoveries and lingering gusty winds. ...Nevada/Utah/Arizona... While strong/gusty winds are forecast across portions of southern Nevada/Utah and northern Arizona, increasing low-level moisture should temper fire weather conditions relative to recent days. Nevertheless, locally elevated conditions are possible. ..Elliott.. 09/09/2019 ...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 0132 AM CDT Mon Sep 09 2019 Valid 091200Z - 101200Z ...Synopsis... A broad area of cyclonic flow -- attendant to a deepening mid/upper-level longwave trough -- is forecast to remain over the western CONUS through today. As this occurs, an area of enhanced mid-level flow near the base of the trough is forecast to strengthen while overspreading portions of southern California, the Southwest, and the southern Great Basin. ...Nevada/Utah/Arizona... Efficient vertical mixing of the aforementioned enhanced mid-level flow should allow for several hours of sustained surface winds of 15-20 mph (locally greater) this afternoon. Elevated to locally critical fire weather conditions are likely as these winds overlap near-critical RH values (e.g., around 15%) and receptive fuels. Currently, the expected brief/spotty nature of critical fire weather conditions precludes upgrading to a critical fire weather area. Locally elevated fire weather conditions are also possible in the lee of the Sierra Mountains over portions of western Inyo County in California, where several fires -- including the Taboose fire -- are ongoing. However, the limited coverage of elevated fire weather conditions precludes expanding the current area farther west. ...Southern California: Santa Barbara and Ventura Counties... Locally elevated fire weather conditions may be ongoing at higher elevations (e.g., > 1 kft) of eastern Santa Barbara and western Ventura Counties this morning due to poor overnight RH recoveries and lingering gusty Sundowner winds. While surface winds are forecast to become less gusty during the late morning, elevated fire weather conditions are expected to redevelop by afternoon as surface winds increase. Elevated fire weather conditions may persist through tonight due to poor overnight RH recoveries and gusty winds. ..Elliott.. 09/09/2019 ...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 0132 AM CDT Mon Sep 09 2019 Valid 091200Z - 101200Z ...Synopsis... A broad area of cyclonic flow -- attendant to a deepening mid/upper-level longwave trough -- is forecast to remain over the western CONUS through today. As this occurs, an area of enhanced mid-level flow near the base of the trough is forecast to strengthen while overspreading portions of southern California, the Southwest, and the southern Great Basin. ...Nevada/Utah/Arizona... Efficient vertical mixing of the aforementioned enhanced mid-level flow should allow for several hours of sustained surface winds of 15-20 mph (locally greater) this afternoon. Elevated to locally critical fire weather conditions are likely as these winds overlap near-critical RH values (e.g., around 15%) and receptive fuels. Currently, the expected brief/spotty nature of critical fire weather conditions precludes upgrading to a critical fire weather area. Locally elevated fire weather conditions are also possible in the lee of the Sierra Mountains over portions of western Inyo County in California, where several fires -- including the Taboose fire -- are ongoing. However, the limited coverage of elevated fire weather conditions precludes expanding the current area farther west. ...Southern California: Santa Barbara and Ventura Counties... Locally elevated fire weather conditions may be ongoing at higher elevations (e.g., > 1 kft) of eastern Santa Barbara and western Ventura Counties this morning due to poor overnight RH recoveries and lingering gusty Sundowner winds. While surface winds are forecast to become less gusty during the late morning, elevated fire weather conditions are expected to redevelop by afternoon as surface winds increase. Elevated fire weather conditions may persist through tonight due to poor overnight RH recoveries and gusty winds. ..Elliott.. 09/09/2019 ...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 0132 AM CDT Mon Sep 09 2019 Valid 091200Z - 101200Z ...Synopsis... A broad area of cyclonic flow -- attendant to a deepening mid/upper-level longwave trough -- is forecast to remain over the western CONUS through today. As this occurs, an area of enhanced mid-level flow near the base of the trough is forecast to strengthen while overspreading portions of southern California, the Southwest, and the southern Great Basin. ...Nevada/Utah/Arizona... Efficient vertical mixing of the aforementioned enhanced mid-level flow should allow for several hours of sustained surface winds of 15-20 mph (locally greater) this afternoon. Elevated to locally critical fire weather conditions are likely as these winds overlap near-critical RH values (e.g., around 15%) and receptive fuels. Currently, the expected brief/spotty nature of critical fire weather conditions precludes upgrading to a critical fire weather area. Locally elevated fire weather conditions are also possible in the lee of the Sierra Mountains over portions of western Inyo County in California, where several fires -- including the Taboose fire -- are ongoing. However, the limited coverage of elevated fire weather conditions precludes expanding the current area farther west. ...Southern California: Santa Barbara and Ventura Counties... Locally elevated fire weather conditions may be ongoing at higher elevations (e.g., > 1 kft) of eastern Santa Barbara and western Ventura Counties this morning due to poor overnight RH recoveries and lingering gusty Sundowner winds. While surface winds are forecast to become less gusty during the late morning, elevated fire weather conditions are expected to redevelop by afternoon as surface winds increase. Elevated fire weather conditions may persist through tonight due to poor overnight RH recoveries and gusty winds. ..Elliott.. 09/09/2019 ...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 0132 AM CDT Mon Sep 09 2019 Valid 091200Z - 101200Z ...Synopsis... A broad area of cyclonic flow -- attendant to a deepening mid/upper-level longwave trough -- is forecast to remain over the western CONUS through today. As this occurs, an area of enhanced mid-level flow near the base of the trough is forecast to strengthen while overspreading portions of southern California, the Southwest, and the southern Great Basin. ...Nevada/Utah/Arizona... Efficient vertical mixing of the aforementioned enhanced mid-level flow should allow for several hours of sustained surface winds of 15-20 mph (locally greater) this afternoon. Elevated to locally critical fire weather conditions are likely as these winds overlap near-critical RH values (e.g., around 15%) and receptive fuels. Currently, the expected brief/spotty nature of critical fire weather conditions precludes upgrading to a critical fire weather area. Locally elevated fire weather conditions are also possible in the lee of the Sierra Mountains over portions of western Inyo County in California, where several fires -- including the Taboose fire -- are ongoing. However, the limited coverage of elevated fire weather conditions precludes expanding the current area farther west. ...Southern California: Santa Barbara and Ventura Counties... Locally elevated fire weather conditions may be ongoing at higher elevations (e.g., > 1 kft) of eastern Santa Barbara and western Ventura Counties this morning due to poor overnight RH recoveries and lingering gusty Sundowner winds. While surface winds are forecast to become less gusty during the late morning, elevated fire weather conditions are expected to redevelop by afternoon as surface winds increase. Elevated fire weather conditions may persist through tonight due to poor overnight RH recoveries and gusty winds. ..Elliott.. 09/09/2019 ...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 0132 AM CDT Mon Sep 09 2019 Valid 091200Z - 101200Z ...Synopsis... A broad area of cyclonic flow -- attendant to a deepening mid/upper-level longwave trough -- is forecast to remain over the western CONUS through today. As this occurs, an area of enhanced mid-level flow near the base of the trough is forecast to strengthen while overspreading portions of southern California, the Southwest, and the southern Great Basin. ...Nevada/Utah/Arizona... Efficient vertical mixing of the aforementioned enhanced mid-level flow should allow for several hours of sustained surface winds of 15-20 mph (locally greater) this afternoon. Elevated to locally critical fire weather conditions are likely as these winds overlap near-critical RH values (e.g., around 15%) and receptive fuels. Currently, the expected brief/spotty nature of critical fire weather conditions precludes upgrading to a critical fire weather area. Locally elevated fire weather conditions are also possible in the lee of the Sierra Mountains over portions of western Inyo County in California, where several fires -- including the Taboose fire -- are ongoing. However, the limited coverage of elevated fire weather conditions precludes expanding the current area farther west. ...Southern California: Santa Barbara and Ventura Counties... Locally elevated fire weather conditions may be ongoing at higher elevations (e.g., > 1 kft) of eastern Santa Barbara and western Ventura Counties this morning due to poor overnight RH recoveries and lingering gusty Sundowner winds. While surface winds are forecast to become less gusty during the late morning, elevated fire weather conditions are expected to redevelop by afternoon as surface winds increase. Elevated fire weather conditions may persist through tonight due to poor overnight RH recoveries and gusty winds. ..Elliott.. 09/09/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1246 AM CDT Mon Sep 09 2019 Valid 101200Z - 111200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHWEST AND NORTH-CENTRAL NEBRASKA... ...SUMMARY... Thunderstorms associated with severe wind gusts, isolated large hail and perhaps a tornado threat will be possible across parts of the central Plains on Tuesday. ...Central and Northern Plains... A shortwave ridge will move northeastward across the northern Plains as southwest mid-level flow becomes established in its wake. At the surface, a lee trough will deepen as a corridor of maximized low-level moisture sets up from Iowa into northern Nebraska by afternoon. Thunderstorm development appears most likely to occur during the late afternoon along the western edge of the strongest instability from southeast Wyoming into northwest Nebraska. A cluster of storms is forecast to develop and move eastward across the central Plains during the late afternoon and early evening. NAM and GFS forecast soundings at 00Z/Wednesday across northwestern and north-central Nebraska show MLCAPE of 2000 to 3000 J/kg, 0-6 km shear of 45 to 50 kt and steep mid-level lapse rates. This should be favorable for supercell development. Supercells should be capable of isolated large hail, wind damage and perhaps a tornado threat. Confidence has increased that a cluster of severe storms will move eastward from northwest Nebraska into north-central Nebraska by early evening. For this reason, a slight risk area has been added for this outlook. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% - Slight ..Broyles.. 09/09/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1246 AM CDT Mon Sep 09 2019 Valid 101200Z - 111200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHWEST AND NORTH-CENTRAL NEBRASKA... ...SUMMARY... Thunderstorms associated with severe wind gusts, isolated large hail and perhaps a tornado threat will be possible across parts of the central Plains on Tuesday. ...Central and Northern Plains... A shortwave ridge will move northeastward across the northern Plains as southwest mid-level flow becomes established in its wake. At the surface, a lee trough will deepen as a corridor of maximized low-level moisture sets up from Iowa into northern Nebraska by afternoon. Thunderstorm development appears most likely to occur during the late afternoon along the western edge of the strongest instability from southeast Wyoming into northwest Nebraska. A cluster of storms is forecast to develop and move eastward across the central Plains during the late afternoon and early evening. NAM and GFS forecast soundings at 00Z/Wednesday across northwestern and north-central Nebraska show MLCAPE of 2000 to 3000 J/kg, 0-6 km shear of 45 to 50 kt and steep mid-level lapse rates. This should be favorable for supercell development. Supercells should be capable of isolated large hail, wind damage and perhaps a tornado threat. Confidence has increased that a cluster of severe storms will move eastward from northwest Nebraska into north-central Nebraska by early evening. For this reason, a slight risk area has been added for this outlook. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% - Slight ..Broyles.. 09/09/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1246 AM CDT Mon Sep 09 2019 Valid 101200Z - 111200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHWEST AND NORTH-CENTRAL NEBRASKA... ...SUMMARY... Thunderstorms associated with severe wind gusts, isolated large hail and perhaps a tornado threat will be possible across parts of the central Plains on Tuesday. ...Central and Northern Plains... A shortwave ridge will move northeastward across the northern Plains as southwest mid-level flow becomes established in its wake. At the surface, a lee trough will deepen as a corridor of maximized low-level moisture sets up from Iowa into northern Nebraska by afternoon. Thunderstorm development appears most likely to occur during the late afternoon along the western edge of the strongest instability from southeast Wyoming into northwest Nebraska. A cluster of storms is forecast to develop and move eastward across the central Plains during the late afternoon and early evening. NAM and GFS forecast soundings at 00Z/Wednesday across northwestern and north-central Nebraska show MLCAPE of 2000 to 3000 J/kg, 0-6 km shear of 45 to 50 kt and steep mid-level lapse rates. This should be favorable for supercell development. Supercells should be capable of isolated large hail, wind damage and perhaps a tornado threat. Confidence has increased that a cluster of severe storms will move eastward from northwest Nebraska into north-central Nebraska by early evening. For this reason, a slight risk area has been added for this outlook. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% - Slight ..Broyles.. 09/09/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1246 AM CDT Mon Sep 09 2019 Valid 101200Z - 111200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHWEST AND NORTH-CENTRAL NEBRASKA... ...SUMMARY... Thunderstorms associated with severe wind gusts, isolated large hail and perhaps a tornado threat will be possible across parts of the central Plains on Tuesday. ...Central and Northern Plains... A shortwave ridge will move northeastward across the northern Plains as southwest mid-level flow becomes established in its wake. At the surface, a lee trough will deepen as a corridor of maximized low-level moisture sets up from Iowa into northern Nebraska by afternoon. Thunderstorm development appears most likely to occur during the late afternoon along the western edge of the strongest instability from southeast Wyoming into northwest Nebraska. A cluster of storms is forecast to develop and move eastward across the central Plains during the late afternoon and early evening. NAM and GFS forecast soundings at 00Z/Wednesday across northwestern and north-central Nebraska show MLCAPE of 2000 to 3000 J/kg, 0-6 km shear of 45 to 50 kt and steep mid-level lapse rates. This should be favorable for supercell development. Supercells should be capable of isolated large hail, wind damage and perhaps a tornado threat. Confidence has increased that a cluster of severe storms will move eastward from northwest Nebraska into north-central Nebraska by early evening. For this reason, a slight risk area has been added for this outlook. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% - Slight ..Broyles.. 09/09/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Mon Sep 09 2019 Valid 091200Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE IOWA/SOUTHERN MINNESOTA VICINITY... ...SUMMARY... Thunderstorms capable of producing large hail, and strong/gusty winds, and possibly a tornado will be possible across parts of the northern Plains and upper Mississippi Valley Monday afternoon and evening. A few strong/severe storms may also occur over the southern Virginia/northeast North Carolina area. ...Synopsis... A short-wave trough is forecast to shift northeastward across the central and northern Plains, toward the upper Mississippi Valley through the day, ahead of a much larger trough gradually evolving southeastward across the West. Meanwhile, a weak short-wave trough will move quickly east-southeastward from the upper Ohio Valley across the Mid Atlantic region through the first half of the period. Otherwise, short-wave troughing will prevail across the southeastern quarter of the country. At the surface, a baroclinic zone extending from Montana southeastward across the mid Missouri Valley is forecast to shift gradually northeastward across the northern Plains/upper Mississippi Valley/upper Great Lakes region through the period. Meanwhile, a weak/remnant front is forecast to linger from the northeast North Carolina area west-southwestward across the Southeast states, south of Northeast U.S. high pressure. ...Parts of the central and northern Plains into the Upper Midwest... Scattered to isolated thunderstorms are forecast to be ongoing across the risk area at the start of the period, in conjunction with the short-wave trough advancing northeastward across the central/northern Plains. The effects of this convection complicate the forecast -- particularly as it pertains to areas where storm reintensification and/or redevelopment may be most concentrated during the afternoon. Overall, a moist boundary layer will remain in place near and south of the warm front, such that where heating can occur, moderate instability will evolve. As such, storm development is expected, and at this time it appears will be most concentrated over the Iowa/southern Minnesota vicinity near where the warm front is expected to reside during the afternoon. Other, more isolated storms may develop southwestward across Nebraska and into western Kansas, though with this area in the wake of the short-wave troughing, subsidence should limit storm coverage across this region. Still, with ample instability and modest shear, a stronger storm or two may produce large hail or gusty winds during the afternoon. Still, greater risk will remain farther north, nearer the northeastward-advancing warm front and ahead of the mid-level feature. With stronger flow aloft across this region, organized storms are expected -- though mode remains uncertain. Any isolated cells which can develop -- particularly near the warm front -- would be capable of producing large hail and locally damaging winds, and possibly a tornado. However, a more clustered/loosely linear storm mode appears likely to evolve, with attendant risks for mainly damaging winds and hail. As a south-southwesterly low-level jet strengthens into the evening, elevated convection should increase in coverage into the Great Lakes area, where some risk for hail may linger well after dark. ...Southern Virginia/northeast North Carolina... As a short-wave trough moves quickly across the central Appalachians and into the Mid Atlantic region through the afternoon, a few thunderstorms are forecast to develop -- possibly over the higher terrain, as well as in the vicinity of the surface boundary progged to be lingering over the northeast North Carolina area. An amply moist/unstable environment will support the storms, and with moderate mid-level west-northwesterly flow shifting across the region, a few stronger storms may evolve. As such, local risk for damaging winds -- and possibly marginal hail -- remains apparent, prior to the onset of diurnal cooling. ..Goss/Elliott.. 09/09/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Mon Sep 09 2019 Valid 091200Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE IOWA/SOUTHERN MINNESOTA VICINITY... ...SUMMARY... Thunderstorms capable of producing large hail, and strong/gusty winds, and possibly a tornado will be possible across parts of the northern Plains and upper Mississippi Valley Monday afternoon and evening. A few strong/severe storms may also occur over the southern Virginia/northeast North Carolina area. ...Synopsis... A short-wave trough is forecast to shift northeastward across the central and northern Plains, toward the upper Mississippi Valley through the day, ahead of a much larger trough gradually evolving southeastward across the West. Meanwhile, a weak short-wave trough will move quickly east-southeastward from the upper Ohio Valley across the Mid Atlantic region through the first half of the period. Otherwise, short-wave troughing will prevail across the southeastern quarter of the country. At the surface, a baroclinic zone extending from Montana southeastward across the mid Missouri Valley is forecast to shift gradually northeastward across the northern Plains/upper Mississippi Valley/upper Great Lakes region through the period. Meanwhile, a weak/remnant front is forecast to linger from the northeast North Carolina area west-southwestward across the Southeast states, south of Northeast U.S. high pressure. ...Parts of the central and northern Plains into the Upper Midwest... Scattered to isolated thunderstorms are forecast to be ongoing across the risk area at the start of the period, in conjunction with the short-wave trough advancing northeastward across the central/northern Plains. The effects of this convection complicate the forecast -- particularly as it pertains to areas where storm reintensification and/or redevelopment may be most concentrated during the afternoon. Overall, a moist boundary layer will remain in place near and south of the warm front, such that where heating can occur, moderate instability will evolve. As such, storm development is expected, and at this time it appears will be most concentrated over the Iowa/southern Minnesota vicinity near where the warm front is expected to reside during the afternoon. Other, more isolated storms may develop southwestward across Nebraska and into western Kansas, though with this area in the wake of the short-wave troughing, subsidence should limit storm coverage across this region. Still, with ample instability and modest shear, a stronger storm or two may produce large hail or gusty winds during the afternoon. Still, greater risk will remain farther north, nearer the northeastward-advancing warm front and ahead of the mid-level feature. With stronger flow aloft across this region, organized storms are expected -- though mode remains uncertain. Any isolated cells which can develop -- particularly near the warm front -- would be capable of producing large hail and locally damaging winds, and possibly a tornado. However, a more clustered/loosely linear storm mode appears likely to evolve, with attendant risks for mainly damaging winds and hail. As a south-southwesterly low-level jet strengthens into the evening, elevated convection should increase in coverage into the Great Lakes area, where some risk for hail may linger well after dark. ...Southern Virginia/northeast North Carolina... As a short-wave trough moves quickly across the central Appalachians and into the Mid Atlantic region through the afternoon, a few thunderstorms are forecast to develop -- possibly over the higher terrain, as well as in the vicinity of the surface boundary progged to be lingering over the northeast North Carolina area. An amply moist/unstable environment will support the storms, and with moderate mid-level west-northwesterly flow shifting across the region, a few stronger storms may evolve. As such, local risk for damaging winds -- and possibly marginal hail -- remains apparent, prior to the onset of diurnal cooling. ..Goss/Elliott.. 09/09/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Mon Sep 09 2019 Valid 091200Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE IOWA/SOUTHERN MINNESOTA VICINITY... ...SUMMARY... Thunderstorms capable of producing large hail, and strong/gusty winds, and possibly a tornado will be possible across parts of the northern Plains and upper Mississippi Valley Monday afternoon and evening. A few strong/severe storms may also occur over the southern Virginia/northeast North Carolina area. ...Synopsis... A short-wave trough is forecast to shift northeastward across the central and northern Plains, toward the upper Mississippi Valley through the day, ahead of a much larger trough gradually evolving southeastward across the West. Meanwhile, a weak short-wave trough will move quickly east-southeastward from the upper Ohio Valley across the Mid Atlantic region through the first half of the period. Otherwise, short-wave troughing will prevail across the southeastern quarter of the country. At the surface, a baroclinic zone extending from Montana southeastward across the mid Missouri Valley is forecast to shift gradually northeastward across the northern Plains/upper Mississippi Valley/upper Great Lakes region through the period. Meanwhile, a weak/remnant front is forecast to linger from the northeast North Carolina area west-southwestward across the Southeast states, south of Northeast U.S. high pressure. ...Parts of the central and northern Plains into the Upper Midwest... Scattered to isolated thunderstorms are forecast to be ongoing across the risk area at the start of the period, in conjunction with the short-wave trough advancing northeastward across the central/northern Plains. The effects of this convection complicate the forecast -- particularly as it pertains to areas where storm reintensification and/or redevelopment may be most concentrated during the afternoon. Overall, a moist boundary layer will remain in place near and south of the warm front, such that where heating can occur, moderate instability will evolve. As such, storm development is expected, and at this time it appears will be most concentrated over the Iowa/southern Minnesota vicinity near where the warm front is expected to reside during the afternoon. Other, more isolated storms may develop southwestward across Nebraska and into western Kansas, though with this area in the wake of the short-wave troughing, subsidence should limit storm coverage across this region. Still, with ample instability and modest shear, a stronger storm or two may produce large hail or gusty winds during the afternoon. Still, greater risk will remain farther north, nearer the northeastward-advancing warm front and ahead of the mid-level feature. With stronger flow aloft across this region, organized storms are expected -- though mode remains uncertain. Any isolated cells which can develop -- particularly near the warm front -- would be capable of producing large hail and locally damaging winds, and possibly a tornado. However, a more clustered/loosely linear storm mode appears likely to evolve, with attendant risks for mainly damaging winds and hail. As a south-southwesterly low-level jet strengthens into the evening, elevated convection should increase in coverage into the Great Lakes area, where some risk for hail may linger well after dark. ...Southern Virginia/northeast North Carolina... As a short-wave trough moves quickly across the central Appalachians and into the Mid Atlantic region through the afternoon, a few thunderstorms are forecast to develop -- possibly over the higher terrain, as well as in the vicinity of the surface boundary progged to be lingering over the northeast North Carolina area. An amply moist/unstable environment will support the storms, and with moderate mid-level west-northwesterly flow shifting across the region, a few stronger storms may evolve. As such, local risk for damaging winds -- and possibly marginal hail -- remains apparent, prior to the onset of diurnal cooling. ..Goss/Elliott.. 09/09/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Mon Sep 09 2019 Valid 091200Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE IOWA/SOUTHERN MINNESOTA VICINITY... ...SUMMARY... Thunderstorms capable of producing large hail, and strong/gusty winds, and possibly a tornado will be possible across parts of the northern Plains and upper Mississippi Valley Monday afternoon and evening. A few strong/severe storms may also occur over the southern Virginia/northeast North Carolina area. ...Synopsis... A short-wave trough is forecast to shift northeastward across the central and northern Plains, toward the upper Mississippi Valley through the day, ahead of a much larger trough gradually evolving southeastward across the West. Meanwhile, a weak short-wave trough will move quickly east-southeastward from the upper Ohio Valley across the Mid Atlantic region through the first half of the period. Otherwise, short-wave troughing will prevail across the southeastern quarter of the country. At the surface, a baroclinic zone extending from Montana southeastward across the mid Missouri Valley is forecast to shift gradually northeastward across the northern Plains/upper Mississippi Valley/upper Great Lakes region through the period. Meanwhile, a weak/remnant front is forecast to linger from the northeast North Carolina area west-southwestward across the Southeast states, south of Northeast U.S. high pressure. ...Parts of the central and northern Plains into the Upper Midwest... Scattered to isolated thunderstorms are forecast to be ongoing across the risk area at the start of the period, in conjunction with the short-wave trough advancing northeastward across the central/northern Plains. The effects of this convection complicate the forecast -- particularly as it pertains to areas where storm reintensification and/or redevelopment may be most concentrated during the afternoon. Overall, a moist boundary layer will remain in place near and south of the warm front, such that where heating can occur, moderate instability will evolve. As such, storm development is expected, and at this time it appears will be most concentrated over the Iowa/southern Minnesota vicinity near where the warm front is expected to reside during the afternoon. Other, more isolated storms may develop southwestward across Nebraska and into western Kansas, though with this area in the wake of the short-wave troughing, subsidence should limit storm coverage across this region. Still, with ample instability and modest shear, a stronger storm or two may produce large hail or gusty winds during the afternoon. Still, greater risk will remain farther north, nearer the northeastward-advancing warm front and ahead of the mid-level feature. With stronger flow aloft across this region, organized storms are expected -- though mode remains uncertain. Any isolated cells which can develop -- particularly near the warm front -- would be capable of producing large hail and locally damaging winds, and possibly a tornado. However, a more clustered/loosely linear storm mode appears likely to evolve, with attendant risks for mainly damaging winds and hail. As a south-southwesterly low-level jet strengthens into the evening, elevated convection should increase in coverage into the Great Lakes area, where some risk for hail may linger well after dark. ...Southern Virginia/northeast North Carolina... As a short-wave trough moves quickly across the central Appalachians and into the Mid Atlantic region through the afternoon, a few thunderstorms are forecast to develop -- possibly over the higher terrain, as well as in the vicinity of the surface boundary progged to be lingering over the northeast North Carolina area. An amply moist/unstable environment will support the storms, and with moderate mid-level west-northwesterly flow shifting across the region, a few stronger storms may evolve. As such, local risk for damaging winds -- and possibly marginal hail -- remains apparent, prior to the onset of diurnal cooling. ..Goss/Elliott.. 09/09/2019 Read more