Severe Storms

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0727 AM CDT Thu Sep 19 2019 Valid 191300Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TODAY NEAR THE UPPER TX COAST...AND THIS AFTERNOON/EVENING FOR PARTS OF THE CENTRAL AND SOUTHERN HIGH PLAINS... ...SUMMARY... Thunderstorms capable of isolated damaging winds and marginally severe hail will be possible in parts of the central and southern High Plains this afternoon and evening. A brief tornado or two will also be possible near the upper Texas coast. ...Central/southern High Plains this afternoon/evening... A midlevel trough will move eastward over NV/ID and UT by tonight, with subtle/diffuse speed maxima preceding the trough from the southern Rockies to the central High Plains. An associated broad surface low will form in WY and move toward the northern High Plains by early Friday, with a lee trough extending southeastward into eastern CO. Surface heating and boundary-layer dewpoints in the 60s east of the lee trough will contribute to MLCAPE near 2000 J/kg this afternoon/evening. Forcing for ascent will be weak at best on the larger scale, with storm initiation relying on surface heating to remove convective inhibition. Still, scattered thunderstorms are expected to form this afternoon and persist into this evening along and east of the lee trough, and along the northwest edge of a midlevel moisture plume across the southern High Plains. Steep lapse rates will promote some potential for strong outflow winds with downbursts, as well as marginally severe hail. Deep-layer vertical shear will be weak across western KS where multicell clusters will be the main storm mode, and slightly stronger across the TX Panhandle where some transient supercell structures will be possible. ...Southeast TX today... Extreme rainfall has occurred overnight between Houston and Beaumont with training convection which has been maintained by 35 kt south-southwesterly inflow of 100 mb mean mixing ratios near 19 g/kg (77-80 F dewpoints) into a stationary, rain-reinforced boundary. Back-building to the west will become more probable during the day with the stronger low-level inflow focused into the west flank of the ongoing convection, and as surface heating occurs to the west. There will still be sufficient low-level shear/hodograph curvature for a few rotating storms and a brief/weak tornado or two in this band the first half of the day, with a gradual decrease in low-level flow/shear is expected by later this afternoon. ...Northern High Plains through tonight... The richer low-level moisture is confined to NE/KS this morning, and moisture is likely to remain limited across eastern WY through most of the afternoon. Moisture will increase farther west and north tonight, but this will also be accompanied by a capped boundary layer. Since the limited moisture will likewise limit buoyancy during the diurnal heating cycle, severe storms appear unlikely this afternoon. The cap and only weak forcing for ascent until Friday morning also suggests that any severe threat overnight will remain too low to warrant an outlook area. ..Thompson/Kerr.. 09/19/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0727 AM CDT Thu Sep 19 2019 Valid 191300Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TODAY NEAR THE UPPER TX COAST...AND THIS AFTERNOON/EVENING FOR PARTS OF THE CENTRAL AND SOUTHERN HIGH PLAINS... ...SUMMARY... Thunderstorms capable of isolated damaging winds and marginally severe hail will be possible in parts of the central and southern High Plains this afternoon and evening. A brief tornado or two will also be possible near the upper Texas coast. ...Central/southern High Plains this afternoon/evening... A midlevel trough will move eastward over NV/ID and UT by tonight, with subtle/diffuse speed maxima preceding the trough from the southern Rockies to the central High Plains. An associated broad surface low will form in WY and move toward the northern High Plains by early Friday, with a lee trough extending southeastward into eastern CO. Surface heating and boundary-layer dewpoints in the 60s east of the lee trough will contribute to MLCAPE near 2000 J/kg this afternoon/evening. Forcing for ascent will be weak at best on the larger scale, with storm initiation relying on surface heating to remove convective inhibition. Still, scattered thunderstorms are expected to form this afternoon and persist into this evening along and east of the lee trough, and along the northwest edge of a midlevel moisture plume across the southern High Plains. Steep lapse rates will promote some potential for strong outflow winds with downbursts, as well as marginally severe hail. Deep-layer vertical shear will be weak across western KS where multicell clusters will be the main storm mode, and slightly stronger across the TX Panhandle where some transient supercell structures will be possible. ...Southeast TX today... Extreme rainfall has occurred overnight between Houston and Beaumont with training convection which has been maintained by 35 kt south-southwesterly inflow of 100 mb mean mixing ratios near 19 g/kg (77-80 F dewpoints) into a stationary, rain-reinforced boundary. Back-building to the west will become more probable during the day with the stronger low-level inflow focused into the west flank of the ongoing convection, and as surface heating occurs to the west. There will still be sufficient low-level shear/hodograph curvature for a few rotating storms and a brief/weak tornado or two in this band the first half of the day, with a gradual decrease in low-level flow/shear is expected by later this afternoon. ...Northern High Plains through tonight... The richer low-level moisture is confined to NE/KS this morning, and moisture is likely to remain limited across eastern WY through most of the afternoon. Moisture will increase farther west and north tonight, but this will also be accompanied by a capped boundary layer. Since the limited moisture will likewise limit buoyancy during the diurnal heating cycle, severe storms appear unlikely this afternoon. The cap and only weak forcing for ascent until Friday morning also suggests that any severe threat overnight will remain too low to warrant an outlook area. ..Thompson/Kerr.. 09/19/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0727 AM CDT Thu Sep 19 2019 Valid 191300Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TODAY NEAR THE UPPER TX COAST...AND THIS AFTERNOON/EVENING FOR PARTS OF THE CENTRAL AND SOUTHERN HIGH PLAINS... ...SUMMARY... Thunderstorms capable of isolated damaging winds and marginally severe hail will be possible in parts of the central and southern High Plains this afternoon and evening. A brief tornado or two will also be possible near the upper Texas coast. ...Central/southern High Plains this afternoon/evening... A midlevel trough will move eastward over NV/ID and UT by tonight, with subtle/diffuse speed maxima preceding the trough from the southern Rockies to the central High Plains. An associated broad surface low will form in WY and move toward the northern High Plains by early Friday, with a lee trough extending southeastward into eastern CO. Surface heating and boundary-layer dewpoints in the 60s east of the lee trough will contribute to MLCAPE near 2000 J/kg this afternoon/evening. Forcing for ascent will be weak at best on the larger scale, with storm initiation relying on surface heating to remove convective inhibition. Still, scattered thunderstorms are expected to form this afternoon and persist into this evening along and east of the lee trough, and along the northwest edge of a midlevel moisture plume across the southern High Plains. Steep lapse rates will promote some potential for strong outflow winds with downbursts, as well as marginally severe hail. Deep-layer vertical shear will be weak across western KS where multicell clusters will be the main storm mode, and slightly stronger across the TX Panhandle where some transient supercell structures will be possible. ...Southeast TX today... Extreme rainfall has occurred overnight between Houston and Beaumont with training convection which has been maintained by 35 kt south-southwesterly inflow of 100 mb mean mixing ratios near 19 g/kg (77-80 F dewpoints) into a stationary, rain-reinforced boundary. Back-building to the west will become more probable during the day with the stronger low-level inflow focused into the west flank of the ongoing convection, and as surface heating occurs to the west. There will still be sufficient low-level shear/hodograph curvature for a few rotating storms and a brief/weak tornado or two in this band the first half of the day, with a gradual decrease in low-level flow/shear is expected by later this afternoon. ...Northern High Plains through tonight... The richer low-level moisture is confined to NE/KS this morning, and moisture is likely to remain limited across eastern WY through most of the afternoon. Moisture will increase farther west and north tonight, but this will also be accompanied by a capped boundary layer. Since the limited moisture will likewise limit buoyancy during the diurnal heating cycle, severe storms appear unlikely this afternoon. The cap and only weak forcing for ascent until Friday morning also suggests that any severe threat overnight will remain too low to warrant an outlook area. ..Thompson/Kerr.. 09/19/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0727 AM CDT Thu Sep 19 2019 Valid 191300Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TODAY NEAR THE UPPER TX COAST...AND THIS AFTERNOON/EVENING FOR PARTS OF THE CENTRAL AND SOUTHERN HIGH PLAINS... ...SUMMARY... Thunderstorms capable of isolated damaging winds and marginally severe hail will be possible in parts of the central and southern High Plains this afternoon and evening. A brief tornado or two will also be possible near the upper Texas coast. ...Central/southern High Plains this afternoon/evening... A midlevel trough will move eastward over NV/ID and UT by tonight, with subtle/diffuse speed maxima preceding the trough from the southern Rockies to the central High Plains. An associated broad surface low will form in WY and move toward the northern High Plains by early Friday, with a lee trough extending southeastward into eastern CO. Surface heating and boundary-layer dewpoints in the 60s east of the lee trough will contribute to MLCAPE near 2000 J/kg this afternoon/evening. Forcing for ascent will be weak at best on the larger scale, with storm initiation relying on surface heating to remove convective inhibition. Still, scattered thunderstorms are expected to form this afternoon and persist into this evening along and east of the lee trough, and along the northwest edge of a midlevel moisture plume across the southern High Plains. Steep lapse rates will promote some potential for strong outflow winds with downbursts, as well as marginally severe hail. Deep-layer vertical shear will be weak across western KS where multicell clusters will be the main storm mode, and slightly stronger across the TX Panhandle where some transient supercell structures will be possible. ...Southeast TX today... Extreme rainfall has occurred overnight between Houston and Beaumont with training convection which has been maintained by 35 kt south-southwesterly inflow of 100 mb mean mixing ratios near 19 g/kg (77-80 F dewpoints) into a stationary, rain-reinforced boundary. Back-building to the west will become more probable during the day with the stronger low-level inflow focused into the west flank of the ongoing convection, and as surface heating occurs to the west. There will still be sufficient low-level shear/hodograph curvature for a few rotating storms and a brief/weak tornado or two in this band the first half of the day, with a gradual decrease in low-level flow/shear is expected by later this afternoon. ...Northern High Plains through tonight... The richer low-level moisture is confined to NE/KS this morning, and moisture is likely to remain limited across eastern WY through most of the afternoon. Moisture will increase farther west and north tonight, but this will also be accompanied by a capped boundary layer. Since the limited moisture will likewise limit buoyancy during the diurnal heating cycle, severe storms appear unlikely this afternoon. The cap and only weak forcing for ascent until Friday morning also suggests that any severe threat overnight will remain too low to warrant an outlook area. ..Thompson/Kerr.. 09/19/2019 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0353 AM CDT Thu Sep 19 2019 Valid 221200Z - 271200Z ...DISCUSSION... On Sunday/D4, a shortwave trough is forecast to move across the upper Mississippi Valley and Great Lakes, though models differ on speed and amplification. Regardless, thunderstorms are likely along the cold front, roughly from Lower Michigan into Missouri. Unidirectional southwest winds along the front suggest a degree of wind threat, though predictability is currently low. This trough will continue eastward into Monday/D5, but instability will be low over the Ohio Valley and Northeast. Meanwhile to the west, good model agreement exists with an upper low that is forecast to drop south across Nevada and into Arizona on Monday/D5. Increasing winds aloft as well as upslope along the rim with gulf moisture suggest a few severe storms are possible. Veering winds with height, good speed shear aloft and MLCAPE of 1000-1500 J/kg also indicate supercell potential or bowing segments. If model trends persist, severe probabilities may be added in future outlooks. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0353 AM CDT Thu Sep 19 2019 Valid 221200Z - 271200Z ...DISCUSSION... On Sunday/D4, a shortwave trough is forecast to move across the upper Mississippi Valley and Great Lakes, though models differ on speed and amplification. Regardless, thunderstorms are likely along the cold front, roughly from Lower Michigan into Missouri. Unidirectional southwest winds along the front suggest a degree of wind threat, though predictability is currently low. This trough will continue eastward into Monday/D5, but instability will be low over the Ohio Valley and Northeast. Meanwhile to the west, good model agreement exists with an upper low that is forecast to drop south across Nevada and into Arizona on Monday/D5. Increasing winds aloft as well as upslope along the rim with gulf moisture suggest a few severe storms are possible. Veering winds with height, good speed shear aloft and MLCAPE of 1000-1500 J/kg also indicate supercell potential or bowing segments. If model trends persist, severe probabilities may be added in future outlooks. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0353 AM CDT Thu Sep 19 2019 Valid 221200Z - 271200Z ...DISCUSSION... On Sunday/D4, a shortwave trough is forecast to move across the upper Mississippi Valley and Great Lakes, though models differ on speed and amplification. Regardless, thunderstorms are likely along the cold front, roughly from Lower Michigan into Missouri. Unidirectional southwest winds along the front suggest a degree of wind threat, though predictability is currently low. This trough will continue eastward into Monday/D5, but instability will be low over the Ohio Valley and Northeast. Meanwhile to the west, good model agreement exists with an upper low that is forecast to drop south across Nevada and into Arizona on Monday/D5. Increasing winds aloft as well as upslope along the rim with gulf moisture suggest a few severe storms are possible. Veering winds with height, good speed shear aloft and MLCAPE of 1000-1500 J/kg also indicate supercell potential or bowing segments. If model trends persist, severe probabilities may be added in future outlooks. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0353 AM CDT Thu Sep 19 2019 Valid 221200Z - 271200Z ...DISCUSSION... On Sunday/D4, a shortwave trough is forecast to move across the upper Mississippi Valley and Great Lakes, though models differ on speed and amplification. Regardless, thunderstorms are likely along the cold front, roughly from Lower Michigan into Missouri. Unidirectional southwest winds along the front suggest a degree of wind threat, though predictability is currently low. This trough will continue eastward into Monday/D5, but instability will be low over the Ohio Valley and Northeast. Meanwhile to the west, good model agreement exists with an upper low that is forecast to drop south across Nevada and into Arizona on Monday/D5. Increasing winds aloft as well as upslope along the rim with gulf moisture suggest a few severe storms are possible. Veering winds with height, good speed shear aloft and MLCAPE of 1000-1500 J/kg also indicate supercell potential or bowing segments. If model trends persist, severe probabilities may be added in future outlooks. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0232 AM CDT Thu Sep 19 2019 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS KANSAS...NORTHERN MISSOURI AND IOWA... ...SUMMARY... Severe storms are possible across parts of the Plains on Saturday, most notably from Kansas into Iowa. ...Synopsis... An upper trough will move east across the northern Plains and toward the Great Lakes, with a broad zone of strong southwest winds aloft encompassing much of the central and northern Plains, upper MS valley and Great Lakes. The primary surface trough will extend from northern ND and MN into Ontario, with a cold front roughly from MN to KS by Saturday afternoon. Ahead of this front, mid to upper 60s F dewpoints will be widespread, and will contribute to areas of moderate instability. The most favorable combination of instability, lift, and shear appears to be from KS northeastward into IA and northern MO, although severe storm potential exists as far north as MN and WI. ...Central Plains... Upper 60s to near 70 F dewpoints are forecast to move north over OK, KS, MO and IA, with a cold front roughly from central KS into western IA by peak heating. Given the very moist air mass, capping will be minimal and storms may form early in the day from KS into MO in the moist sector with isolated severe possible. Veering winds with height and favorable effective SRH may favor a couple supercells producing either strong wind gusts or a brief/weak tornado. The most likely time for concentrated severe storms will be during the late afternoon and evening, beneath a strengthening 40-50 kt low-level jet centered over KS. Good model agreement exists within the zone from KS into northern MO and IA depicting significant storm coverage. Damaging wind appears to be the main concern during the evening, and storms may persist into IA and even western IL given strong westerlies aloft. ...Upper Mississippi Valley... Scattered storms are expected throughout the day from MN into WI. Early day storms may be associated with warm advection at 850 mb, with a secondary area of storms along the cold front as it moves across MN during the day. Marginal instability is forecast, with long hodographs suggesting a wind or marginal hail threat. It appears that a dry slot will move over the region during the day, with veering winds above the surface. In addition, 850 mb wind convergence will focus farther north into Ontario, with some models showing speed divergence over MN. Therefore at this time, only isolated severe storms are forecast. ..Jewell.. 09/19/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0232 AM CDT Thu Sep 19 2019 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS KANSAS...NORTHERN MISSOURI AND IOWA... ...SUMMARY... Severe storms are possible across parts of the Plains on Saturday, most notably from Kansas into Iowa. ...Synopsis... An upper trough will move east across the northern Plains and toward the Great Lakes, with a broad zone of strong southwest winds aloft encompassing much of the central and northern Plains, upper MS valley and Great Lakes. The primary surface trough will extend from northern ND and MN into Ontario, with a cold front roughly from MN to KS by Saturday afternoon. Ahead of this front, mid to upper 60s F dewpoints will be widespread, and will contribute to areas of moderate instability. The most favorable combination of instability, lift, and shear appears to be from KS northeastward into IA and northern MO, although severe storm potential exists as far north as MN and WI. ...Central Plains... Upper 60s to near 70 F dewpoints are forecast to move north over OK, KS, MO and IA, with a cold front roughly from central KS into western IA by peak heating. Given the very moist air mass, capping will be minimal and storms may form early in the day from KS into MO in the moist sector with isolated severe possible. Veering winds with height and favorable effective SRH may favor a couple supercells producing either strong wind gusts or a brief/weak tornado. The most likely time for concentrated severe storms will be during the late afternoon and evening, beneath a strengthening 40-50 kt low-level jet centered over KS. Good model agreement exists within the zone from KS into northern MO and IA depicting significant storm coverage. Damaging wind appears to be the main concern during the evening, and storms may persist into IA and even western IL given strong westerlies aloft. ...Upper Mississippi Valley... Scattered storms are expected throughout the day from MN into WI. Early day storms may be associated with warm advection at 850 mb, with a secondary area of storms along the cold front as it moves across MN during the day. Marginal instability is forecast, with long hodographs suggesting a wind or marginal hail threat. It appears that a dry slot will move over the region during the day, with veering winds above the surface. In addition, 850 mb wind convergence will focus farther north into Ontario, with some models showing speed divergence over MN. Therefore at this time, only isolated severe storms are forecast. ..Jewell.. 09/19/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0232 AM CDT Thu Sep 19 2019 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS KANSAS...NORTHERN MISSOURI AND IOWA... ...SUMMARY... Severe storms are possible across parts of the Plains on Saturday, most notably from Kansas into Iowa. ...Synopsis... An upper trough will move east across the northern Plains and toward the Great Lakes, with a broad zone of strong southwest winds aloft encompassing much of the central and northern Plains, upper MS valley and Great Lakes. The primary surface trough will extend from northern ND and MN into Ontario, with a cold front roughly from MN to KS by Saturday afternoon. Ahead of this front, mid to upper 60s F dewpoints will be widespread, and will contribute to areas of moderate instability. The most favorable combination of instability, lift, and shear appears to be from KS northeastward into IA and northern MO, although severe storm potential exists as far north as MN and WI. ...Central Plains... Upper 60s to near 70 F dewpoints are forecast to move north over OK, KS, MO and IA, with a cold front roughly from central KS into western IA by peak heating. Given the very moist air mass, capping will be minimal and storms may form early in the day from KS into MO in the moist sector with isolated severe possible. Veering winds with height and favorable effective SRH may favor a couple supercells producing either strong wind gusts or a brief/weak tornado. The most likely time for concentrated severe storms will be during the late afternoon and evening, beneath a strengthening 40-50 kt low-level jet centered over KS. Good model agreement exists within the zone from KS into northern MO and IA depicting significant storm coverage. Damaging wind appears to be the main concern during the evening, and storms may persist into IA and even western IL given strong westerlies aloft. ...Upper Mississippi Valley... Scattered storms are expected throughout the day from MN into WI. Early day storms may be associated with warm advection at 850 mb, with a secondary area of storms along the cold front as it moves across MN during the day. Marginal instability is forecast, with long hodographs suggesting a wind or marginal hail threat. It appears that a dry slot will move over the region during the day, with veering winds above the surface. In addition, 850 mb wind convergence will focus farther north into Ontario, with some models showing speed divergence over MN. Therefore at this time, only isolated severe storms are forecast. ..Jewell.. 09/19/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1248 AM CDT Thu Sep 19 2019 Valid 201200Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER THE NORTHERN PLAINS... ...SUMMARY... Scattered severe storms are possible on Friday across the northern Plains, with isolated activity into the central and southern High Plains. ...Synopsis... An upper trough will move east across the Rockies and into the Plains, with moderate southwesterly winds aloft enhancing shear profiles. Low pressure will develop from eastern WY into ND, with a cold front moving across the Dakotas and Nebraska overnight. Ahead of the front and east of the High Plains lee trough, southerly winds will maintain 60s F dewpoints, with moderate instability developing due to cooling aloft and daytime heating. Elsewhere, high pressure will maintain relatively stable conditions over much of the East. ...Northern Plains... Capping is expected to erode by early afternoon across the warm sector, with a rapid increase in storm coverage along and east of the cold front from far eastern MT/WY into the central and western Dakotas. Deep-layer shear will be modest initially as the stronger winds aloft remain to the west, suggesting mixed storm mode. However, stronger low-level shear and SRH will exist over ND into northwest MN, where a tornado or two is possible. Otherwise, large hail and damaging winds are expected for the remainder of the Slight Risk area. ...Central and southern High Plains... An axis of moderate instability is forecast to develop near the lee trough and dryline from eastern CO into far eastern NM where southeast surface winds will maintain low-level moisture. Models suggest early day storms are possible over the southern High Plains, which increases uncertainty regarding afternoon storm chances. While low-level convergence will exist near the lee trough from CO into KS, most of the lift associated with the upper trough will remain to the north. Conditionally, heating near the dryline may support at least isolated storms along the lee trough from CO to NM to the TX Panhandle. Lengthening hodographs will favor cells capable of large hail. If predictability regarding storm coverage increases in later outlooks, a Slight Risk may be considered. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% - Slight ..Jewell.. 09/19/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1248 AM CDT Thu Sep 19 2019 Valid 201200Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER THE NORTHERN PLAINS... ...SUMMARY... Scattered severe storms are possible on Friday across the northern Plains, with isolated activity into the central and southern High Plains. ...Synopsis... An upper trough will move east across the Rockies and into the Plains, with moderate southwesterly winds aloft enhancing shear profiles. Low pressure will develop from eastern WY into ND, with a cold front moving across the Dakotas and Nebraska overnight. Ahead of the front and east of the High Plains lee trough, southerly winds will maintain 60s F dewpoints, with moderate instability developing due to cooling aloft and daytime heating. Elsewhere, high pressure will maintain relatively stable conditions over much of the East. ...Northern Plains... Capping is expected to erode by early afternoon across the warm sector, with a rapid increase in storm coverage along and east of the cold front from far eastern MT/WY into the central and western Dakotas. Deep-layer shear will be modest initially as the stronger winds aloft remain to the west, suggesting mixed storm mode. However, stronger low-level shear and SRH will exist over ND into northwest MN, where a tornado or two is possible. Otherwise, large hail and damaging winds are expected for the remainder of the Slight Risk area. ...Central and southern High Plains... An axis of moderate instability is forecast to develop near the lee trough and dryline from eastern CO into far eastern NM where southeast surface winds will maintain low-level moisture. Models suggest early day storms are possible over the southern High Plains, which increases uncertainty regarding afternoon storm chances. While low-level convergence will exist near the lee trough from CO into KS, most of the lift associated with the upper trough will remain to the north. Conditionally, heating near the dryline may support at least isolated storms along the lee trough from CO to NM to the TX Panhandle. Lengthening hodographs will favor cells capable of large hail. If predictability regarding storm coverage increases in later outlooks, a Slight Risk may be considered. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% - Slight ..Jewell.. 09/19/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1248 AM CDT Thu Sep 19 2019 Valid 201200Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER THE NORTHERN PLAINS... ...SUMMARY... Scattered severe storms are possible on Friday across the northern Plains, with isolated activity into the central and southern High Plains. ...Synopsis... An upper trough will move east across the Rockies and into the Plains, with moderate southwesterly winds aloft enhancing shear profiles. Low pressure will develop from eastern WY into ND, with a cold front moving across the Dakotas and Nebraska overnight. Ahead of the front and east of the High Plains lee trough, southerly winds will maintain 60s F dewpoints, with moderate instability developing due to cooling aloft and daytime heating. Elsewhere, high pressure will maintain relatively stable conditions over much of the East. ...Northern Plains... Capping is expected to erode by early afternoon across the warm sector, with a rapid increase in storm coverage along and east of the cold front from far eastern MT/WY into the central and western Dakotas. Deep-layer shear will be modest initially as the stronger winds aloft remain to the west, suggesting mixed storm mode. However, stronger low-level shear and SRH will exist over ND into northwest MN, where a tornado or two is possible. Otherwise, large hail and damaging winds are expected for the remainder of the Slight Risk area. ...Central and southern High Plains... An axis of moderate instability is forecast to develop near the lee trough and dryline from eastern CO into far eastern NM where southeast surface winds will maintain low-level moisture. Models suggest early day storms are possible over the southern High Plains, which increases uncertainty regarding afternoon storm chances. While low-level convergence will exist near the lee trough from CO into KS, most of the lift associated with the upper trough will remain to the north. Conditionally, heating near the dryline may support at least isolated storms along the lee trough from CO to NM to the TX Panhandle. Lengthening hodographs will favor cells capable of large hail. If predictability regarding storm coverage increases in later outlooks, a Slight Risk may be considered. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% - Slight ..Jewell.. 09/19/2019 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1247 AM CDT Thu Sep 19 2019 Valid 201200Z - 211200Z ...Synopsis... The mid-level trough from Day1/Thursday will shift east on Friday which will increase fire weather concerns in portions of the central Rockies and the central High Plains. Deep mixing will strengthen surface winds across much of this region with wind speeds of 20 to 30 mph expected. Relative humidity will vary across the area from around 15 percent up to 30 percent. Locally critical fire weather conditions are possible within the broader elevated delineation, but the highest likelihood of critical conditions remains ambiguous at this time. Winds are expected to be strongest in Wyoming where relative humidity will be the highest, and lightest in eastern Utah where relative humidity will be the lowest. In eastern Colorado, both winds and relative humidity are expected to be borderline critical. Will continue to monitor the forecast for potential critical additions, especially if forecast guidance is drier or lee cyclogenesis is stronger, both of which would likely increase the likelihood of critical fire weather conditions. ..Bentley.. 09/19/2019 ...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 1247 AM CDT Thu Sep 19 2019 Valid 201200Z - 211200Z ...Synopsis... The mid-level trough from Day1/Thursday will shift east on Friday which will increase fire weather concerns in portions of the central Rockies and the central High Plains. Deep mixing will strengthen surface winds across much of this region with wind speeds of 20 to 30 mph expected. Relative humidity will vary across the area from around 15 percent up to 30 percent. Locally critical fire weather conditions are possible within the broader elevated delineation, but the highest likelihood of critical conditions remains ambiguous at this time. Winds are expected to be strongest in Wyoming where relative humidity will be the highest, and lightest in eastern Utah where relative humidity will be the lowest. In eastern Colorado, both winds and relative humidity are expected to be borderline critical. Will continue to monitor the forecast for potential critical additions, especially if forecast guidance is drier or lee cyclogenesis is stronger, both of which would likely increase the likelihood of critical fire weather conditions. ..Bentley.. 09/19/2019 ...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 1247 AM CDT Thu Sep 19 2019 Valid 201200Z - 211200Z ...Synopsis... The mid-level trough from Day1/Thursday will shift east on Friday which will increase fire weather concerns in portions of the central Rockies and the central High Plains. Deep mixing will strengthen surface winds across much of this region with wind speeds of 20 to 30 mph expected. Relative humidity will vary across the area from around 15 percent up to 30 percent. Locally critical fire weather conditions are possible within the broader elevated delineation, but the highest likelihood of critical conditions remains ambiguous at this time. Winds are expected to be strongest in Wyoming where relative humidity will be the highest, and lightest in eastern Utah where relative humidity will be the lowest. In eastern Colorado, both winds and relative humidity are expected to be borderline critical. Will continue to monitor the forecast for potential critical additions, especially if forecast guidance is drier or lee cyclogenesis is stronger, both of which would likely increase the likelihood of critical fire weather conditions. ..Bentley.. 09/19/2019 ...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 1246 AM CDT Thu Sep 19 2019 Valid 191200Z - 201200Z ...CRITICAL FIRE WEATHER AREA FOR FAR SOUTHEAST NEVADA...NORTHWEST ARIZONA...AND A LARGE PORTION OF UTAH... ...Synopsis... A strong mid-level jet will spread across the Great Basin today ahead of a mid-level closed low. Some of these strong winds are expected to transport toward the surface through deep vertical mixing. Surface winds could be quite strong (30 to 35 mph) in northwest Arizona and southwest Utah with some gusts approaching 50 mph. In addition, this pre-frontal airmass will feature dry surface conditions and RH values around 10 to 20 percent. 20 to 30 mph surface winds are expected farther northeast into most of Wyoming where relative humidity will also be in the 15 to 20 percent range. Isolated critical conditions will be possible in this region, but no critical area was added here due to borderline relative humidity and relatively sparse fuels. ..Bentley.. 09/19/2019 ...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 1246 AM CDT Thu Sep 19 2019 Valid 191200Z - 201200Z ...CRITICAL FIRE WEATHER AREA FOR FAR SOUTHEAST NEVADA...NORTHWEST ARIZONA...AND A LARGE PORTION OF UTAH... ...Synopsis... A strong mid-level jet will spread across the Great Basin today ahead of a mid-level closed low. Some of these strong winds are expected to transport toward the surface through deep vertical mixing. Surface winds could be quite strong (30 to 35 mph) in northwest Arizona and southwest Utah with some gusts approaching 50 mph. In addition, this pre-frontal airmass will feature dry surface conditions and RH values around 10 to 20 percent. 20 to 30 mph surface winds are expected farther northeast into most of Wyoming where relative humidity will also be in the 15 to 20 percent range. Isolated critical conditions will be possible in this region, but no critical area was added here due to borderline relative humidity and relatively sparse fuels. ..Bentley.. 09/19/2019 ...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 1246 AM CDT Thu Sep 19 2019 Valid 191200Z - 201200Z ...CRITICAL FIRE WEATHER AREA FOR FAR SOUTHEAST NEVADA...NORTHWEST ARIZONA...AND A LARGE PORTION OF UTAH... ...Synopsis... A strong mid-level jet will spread across the Great Basin today ahead of a mid-level closed low. Some of these strong winds are expected to transport toward the surface through deep vertical mixing. Surface winds could be quite strong (30 to 35 mph) in northwest Arizona and southwest Utah with some gusts approaching 50 mph. In addition, this pre-frontal airmass will feature dry surface conditions and RH values around 10 to 20 percent. 20 to 30 mph surface winds are expected farther northeast into most of Wyoming where relative humidity will also be in the 15 to 20 percent range. Isolated critical conditions will be possible in this region, but no critical area was added here due to borderline relative humidity and relatively sparse fuels. ..Bentley.. 09/19/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more