Severe Storms

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1254 AM CDT Tue Aug 20 2019 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE NORTHEAST... ...SUMMARY... Scattered storms, some severe, are possible Wednesday over parts of the Northeast, and over much of the central Plains into the mid Mississippi Valley. Damaging wind gusts and marginal hail are possible in both regions. ...Synopsis... An upper low will move from Ontario into Quebec, with a leading shortwave trough moving across the Great Lakes during the day and New England overnight. A cold front will stretch from southwest Ontario to IL by late afternoon, with mid to upper 60s F dewpoints spreading into the Northeast. Aiding moisture advection as well as low-level shear will be southwesterly 850 mb winds increasing to 25-30 kt, while mid to upper level winds increase throughout the period. To the west, a convectively reinforced boundary is expected across northern MO, KS, and into eastern CO, with a very moist and unstable air mass to the south. Bouts of thunderstorms are likely throughout the period near this boundary, with the greatest concentration over MO, closer to the Great Lakes trough influence. ...Northeastern states... Heating will lead to numerous thunderstorms across the moist sector by 18Z over much of NY and northeast PA, expanding across New England during the afternoon. Around 30-35 kt of deep-layer shear and 100-150 m2/s2 effective SRH will be sufficient to sustain severe storms, including isolated supercells capable of marginal hail, a brief/weak tornado, or damaging wind. Due to the expected large number of storms, mergers are likely, and a few line segments may form as well. Storms may persist well into the evening and overnight into northern New England when the stronger height falls occur. ...Central Plains into the Mid MS and lower OH Valley... Storms are expected to be ongoing from NE across MO and into IL Wednesday morning along an east-west oriented front, and where substantial instability will exist. This outflow-reinforced front will likely translate south during the day, with continuous areas of storms over KS, MO, and IL. Winds aloft will generally be westerly and below 20 kt, thus disorganized storms are most likely. However, a few small bows are possible, with localized areas of wind damage. Given such strong instability, the strongest storms may produce hail. To the west, east/northeast surface winds will bring a moist air mass into east-central WY and CO, where capping will be a concern. Storms are likely to form over the higher terrain, with a narrow north-south zone of hail or wind threat. Other storms are likely farther south in the well-mixed and hot air, from northeast NM across northern OK and AR, with localized downbursts possible. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 15% - Slight Hail: 5% - Marginal ..Jewell.. 08/20/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1254 AM CDT Tue Aug 20 2019 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE NORTHEAST... ...SUMMARY... Scattered storms, some severe, are possible Wednesday over parts of the Northeast, and over much of the central Plains into the mid Mississippi Valley. Damaging wind gusts and marginal hail are possible in both regions. ...Synopsis... An upper low will move from Ontario into Quebec, with a leading shortwave trough moving across the Great Lakes during the day and New England overnight. A cold front will stretch from southwest Ontario to IL by late afternoon, with mid to upper 60s F dewpoints spreading into the Northeast. Aiding moisture advection as well as low-level shear will be southwesterly 850 mb winds increasing to 25-30 kt, while mid to upper level winds increase throughout the period. To the west, a convectively reinforced boundary is expected across northern MO, KS, and into eastern CO, with a very moist and unstable air mass to the south. Bouts of thunderstorms are likely throughout the period near this boundary, with the greatest concentration over MO, closer to the Great Lakes trough influence. ...Northeastern states... Heating will lead to numerous thunderstorms across the moist sector by 18Z over much of NY and northeast PA, expanding across New England during the afternoon. Around 30-35 kt of deep-layer shear and 100-150 m2/s2 effective SRH will be sufficient to sustain severe storms, including isolated supercells capable of marginal hail, a brief/weak tornado, or damaging wind. Due to the expected large number of storms, mergers are likely, and a few line segments may form as well. Storms may persist well into the evening and overnight into northern New England when the stronger height falls occur. ...Central Plains into the Mid MS and lower OH Valley... Storms are expected to be ongoing from NE across MO and into IL Wednesday morning along an east-west oriented front, and where substantial instability will exist. This outflow-reinforced front will likely translate south during the day, with continuous areas of storms over KS, MO, and IL. Winds aloft will generally be westerly and below 20 kt, thus disorganized storms are most likely. However, a few small bows are possible, with localized areas of wind damage. Given such strong instability, the strongest storms may produce hail. To the west, east/northeast surface winds will bring a moist air mass into east-central WY and CO, where capping will be a concern. Storms are likely to form over the higher terrain, with a narrow north-south zone of hail or wind threat. Other storms are likely farther south in the well-mixed and hot air, from northeast NM across northern OK and AR, with localized downbursts possible. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 15% - Slight Hail: 5% - Marginal ..Jewell.. 08/20/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1254 AM CDT Tue Aug 20 2019 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE NORTHEAST... ...SUMMARY... Scattered storms, some severe, are possible Wednesday over parts of the Northeast, and over much of the central Plains into the mid Mississippi Valley. Damaging wind gusts and marginal hail are possible in both regions. ...Synopsis... An upper low will move from Ontario into Quebec, with a leading shortwave trough moving across the Great Lakes during the day and New England overnight. A cold front will stretch from southwest Ontario to IL by late afternoon, with mid to upper 60s F dewpoints spreading into the Northeast. Aiding moisture advection as well as low-level shear will be southwesterly 850 mb winds increasing to 25-30 kt, while mid to upper level winds increase throughout the period. To the west, a convectively reinforced boundary is expected across northern MO, KS, and into eastern CO, with a very moist and unstable air mass to the south. Bouts of thunderstorms are likely throughout the period near this boundary, with the greatest concentration over MO, closer to the Great Lakes trough influence. ...Northeastern states... Heating will lead to numerous thunderstorms across the moist sector by 18Z over much of NY and northeast PA, expanding across New England during the afternoon. Around 30-35 kt of deep-layer shear and 100-150 m2/s2 effective SRH will be sufficient to sustain severe storms, including isolated supercells capable of marginal hail, a brief/weak tornado, or damaging wind. Due to the expected large number of storms, mergers are likely, and a few line segments may form as well. Storms may persist well into the evening and overnight into northern New England when the stronger height falls occur. ...Central Plains into the Mid MS and lower OH Valley... Storms are expected to be ongoing from NE across MO and into IL Wednesday morning along an east-west oriented front, and where substantial instability will exist. This outflow-reinforced front will likely translate south during the day, with continuous areas of storms over KS, MO, and IL. Winds aloft will generally be westerly and below 20 kt, thus disorganized storms are most likely. However, a few small bows are possible, with localized areas of wind damage. Given such strong instability, the strongest storms may produce hail. To the west, east/northeast surface winds will bring a moist air mass into east-central WY and CO, where capping will be a concern. Storms are likely to form over the higher terrain, with a narrow north-south zone of hail or wind threat. Other storms are likely farther south in the well-mixed and hot air, from northeast NM across northern OK and AR, with localized downbursts possible. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 15% - Slight Hail: 5% - Marginal ..Jewell.. 08/20/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1254 AM CDT Tue Aug 20 2019 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE NORTHEAST... ...SUMMARY... Scattered storms, some severe, are possible Wednesday over parts of the Northeast, and over much of the central Plains into the mid Mississippi Valley. Damaging wind gusts and marginal hail are possible in both regions. ...Synopsis... An upper low will move from Ontario into Quebec, with a leading shortwave trough moving across the Great Lakes during the day and New England overnight. A cold front will stretch from southwest Ontario to IL by late afternoon, with mid to upper 60s F dewpoints spreading into the Northeast. Aiding moisture advection as well as low-level shear will be southwesterly 850 mb winds increasing to 25-30 kt, while mid to upper level winds increase throughout the period. To the west, a convectively reinforced boundary is expected across northern MO, KS, and into eastern CO, with a very moist and unstable air mass to the south. Bouts of thunderstorms are likely throughout the period near this boundary, with the greatest concentration over MO, closer to the Great Lakes trough influence. ...Northeastern states... Heating will lead to numerous thunderstorms across the moist sector by 18Z over much of NY and northeast PA, expanding across New England during the afternoon. Around 30-35 kt of deep-layer shear and 100-150 m2/s2 effective SRH will be sufficient to sustain severe storms, including isolated supercells capable of marginal hail, a brief/weak tornado, or damaging wind. Due to the expected large number of storms, mergers are likely, and a few line segments may form as well. Storms may persist well into the evening and overnight into northern New England when the stronger height falls occur. ...Central Plains into the Mid MS and lower OH Valley... Storms are expected to be ongoing from NE across MO and into IL Wednesday morning along an east-west oriented front, and where substantial instability will exist. This outflow-reinforced front will likely translate south during the day, with continuous areas of storms over KS, MO, and IL. Winds aloft will generally be westerly and below 20 kt, thus disorganized storms are most likely. However, a few small bows are possible, with localized areas of wind damage. Given such strong instability, the strongest storms may produce hail. To the west, east/northeast surface winds will bring a moist air mass into east-central WY and CO, where capping will be a concern. Storms are likely to form over the higher terrain, with a narrow north-south zone of hail or wind threat. Other storms are likely farther south in the well-mixed and hot air, from northeast NM across northern OK and AR, with localized downbursts possible. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 15% - Slight Hail: 5% - Marginal ..Jewell.. 08/20/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0102 AM CDT Tue Aug 20 2019 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDDLE MS VALLEY... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN MN... ...SUMMARY... An organized cluster of thunderstorms capable of severe wind gusts and hail will overspread portions of the middle Mississippi and lower Ohio Valleys today. Hail and isolated strong winds are also possible across portions of Minnesota this morning. ...Mid MS Valley eastward across the OH Valley... An organized MCS will likely be moving through south-central/southeast IA early this morning. Expectation is for this MCS to be near its mature phase at this point with a well-developed rear-inflow jet and strong cold pool resulting in strong wind gusts. A few of these gusts could be greater than 75 mph. As the MCS continues southeastward through northwest MO and central IL later this morning and into the early afternoon, it is expected to gradually lose intensity as its cold pool accelerates and loses depth. By the time the MCS reaches IN and western KY, it is expected to be characterized by weakly organized multicells along the cold pool. Even with this anticipated weakening, strong wind gusts are still possible. ...Central High Plains/Central Plains... A cold front is expected to push into the Upper Midwest and central Plains, likely extending from western WI southwestward into northeastern CO during the late afternoon. Moist upslope flow is anticipated into eastern WY/northeast CO behind this front, with the resulting convergence along the lee trough expected to result in thunderstorm initiation. Downstream environment characterized by strong buoyancy and at least moderate vertical shear will support supercell storm structures capable of very large hail and strong wind gusts. These storms are expected to continue eastward into NE during the evening. A strengthening low-level jet will lead to a reinvigoration of any ongoing storms and/or development of new storms, primarily across central and eastern NE. Given the presence of ample low-level moisture and steep mid-level lapse rates, large hail is probable with these storms. Isolated very large hail (i.e. greater than 2" in diameter) is possible. Dry mid-levels could also contribute to strong wind gusts. ...Upper Midwest... Ample low-level moisture and steep mid-level lapse rates will result in strong buoyancy ahead of the approaching cold front this morning across northern/central MN. Stable low-levels (below 850 mb) will likely limit storm strength but large hail and occasional strong gusts through the stable layer are possible. ...Northern Mid-Atlantic... Showers and thunderstorms will likely develop during the afternoon within the moist and diurnally destabilized air mass across the region. Vertical shear will be weak, leading to predominately disorganized, outflow-dominant multicells. Even so, the very moist air mass and steep low-level lapse rates support water-loaded downbursts capable of damaging wind gusts. ..Mosier/Nauslar.. 08/20/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0102 AM CDT Tue Aug 20 2019 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDDLE MS VALLEY... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN MN... ...SUMMARY... An organized cluster of thunderstorms capable of severe wind gusts and hail will overspread portions of the middle Mississippi and lower Ohio Valleys today. Hail and isolated strong winds are also possible across portions of Minnesota this morning. ...Mid MS Valley eastward across the OH Valley... An organized MCS will likely be moving through south-central/southeast IA early this morning. Expectation is for this MCS to be near its mature phase at this point with a well-developed rear-inflow jet and strong cold pool resulting in strong wind gusts. A few of these gusts could be greater than 75 mph. As the MCS continues southeastward through northwest MO and central IL later this morning and into the early afternoon, it is expected to gradually lose intensity as its cold pool accelerates and loses depth. By the time the MCS reaches IN and western KY, it is expected to be characterized by weakly organized multicells along the cold pool. Even with this anticipated weakening, strong wind gusts are still possible. ...Central High Plains/Central Plains... A cold front is expected to push into the Upper Midwest and central Plains, likely extending from western WI southwestward into northeastern CO during the late afternoon. Moist upslope flow is anticipated into eastern WY/northeast CO behind this front, with the resulting convergence along the lee trough expected to result in thunderstorm initiation. Downstream environment characterized by strong buoyancy and at least moderate vertical shear will support supercell storm structures capable of very large hail and strong wind gusts. These storms are expected to continue eastward into NE during the evening. A strengthening low-level jet will lead to a reinvigoration of any ongoing storms and/or development of new storms, primarily across central and eastern NE. Given the presence of ample low-level moisture and steep mid-level lapse rates, large hail is probable with these storms. Isolated very large hail (i.e. greater than 2" in diameter) is possible. Dry mid-levels could also contribute to strong wind gusts. ...Upper Midwest... Ample low-level moisture and steep mid-level lapse rates will result in strong buoyancy ahead of the approaching cold front this morning across northern/central MN. Stable low-levels (below 850 mb) will likely limit storm strength but large hail and occasional strong gusts through the stable layer are possible. ...Northern Mid-Atlantic... Showers and thunderstorms will likely develop during the afternoon within the moist and diurnally destabilized air mass across the region. Vertical shear will be weak, leading to predominately disorganized, outflow-dominant multicells. Even so, the very moist air mass and steep low-level lapse rates support water-loaded downbursts capable of damaging wind gusts. ..Mosier/Nauslar.. 08/20/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0102 AM CDT Tue Aug 20 2019 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDDLE MS VALLEY... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN MN... ...SUMMARY... An organized cluster of thunderstorms capable of severe wind gusts and hail will overspread portions of the middle Mississippi and lower Ohio Valleys today. Hail and isolated strong winds are also possible across portions of Minnesota this morning. ...Mid MS Valley eastward across the OH Valley... An organized MCS will likely be moving through south-central/southeast IA early this morning. Expectation is for this MCS to be near its mature phase at this point with a well-developed rear-inflow jet and strong cold pool resulting in strong wind gusts. A few of these gusts could be greater than 75 mph. As the MCS continues southeastward through northwest MO and central IL later this morning and into the early afternoon, it is expected to gradually lose intensity as its cold pool accelerates and loses depth. By the time the MCS reaches IN and western KY, it is expected to be characterized by weakly organized multicells along the cold pool. Even with this anticipated weakening, strong wind gusts are still possible. ...Central High Plains/Central Plains... A cold front is expected to push into the Upper Midwest and central Plains, likely extending from western WI southwestward into northeastern CO during the late afternoon. Moist upslope flow is anticipated into eastern WY/northeast CO behind this front, with the resulting convergence along the lee trough expected to result in thunderstorm initiation. Downstream environment characterized by strong buoyancy and at least moderate vertical shear will support supercell storm structures capable of very large hail and strong wind gusts. These storms are expected to continue eastward into NE during the evening. A strengthening low-level jet will lead to a reinvigoration of any ongoing storms and/or development of new storms, primarily across central and eastern NE. Given the presence of ample low-level moisture and steep mid-level lapse rates, large hail is probable with these storms. Isolated very large hail (i.e. greater than 2" in diameter) is possible. Dry mid-levels could also contribute to strong wind gusts. ...Upper Midwest... Ample low-level moisture and steep mid-level lapse rates will result in strong buoyancy ahead of the approaching cold front this morning across northern/central MN. Stable low-levels (below 850 mb) will likely limit storm strength but large hail and occasional strong gusts through the stable layer are possible. ...Northern Mid-Atlantic... Showers and thunderstorms will likely develop during the afternoon within the moist and diurnally destabilized air mass across the region. Vertical shear will be weak, leading to predominately disorganized, outflow-dominant multicells. Even so, the very moist air mass and steep low-level lapse rates support water-loaded downbursts capable of damaging wind gusts. ..Mosier/Nauslar.. 08/20/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0102 AM CDT Tue Aug 20 2019 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDDLE MS VALLEY... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN MN... ...SUMMARY... An organized cluster of thunderstorms capable of severe wind gusts and hail will overspread portions of the middle Mississippi and lower Ohio Valleys today. Hail and isolated strong winds are also possible across portions of Minnesota this morning. ...Mid MS Valley eastward across the OH Valley... An organized MCS will likely be moving through south-central/southeast IA early this morning. Expectation is for this MCS to be near its mature phase at this point with a well-developed rear-inflow jet and strong cold pool resulting in strong wind gusts. A few of these gusts could be greater than 75 mph. As the MCS continues southeastward through northwest MO and central IL later this morning and into the early afternoon, it is expected to gradually lose intensity as its cold pool accelerates and loses depth. By the time the MCS reaches IN and western KY, it is expected to be characterized by weakly organized multicells along the cold pool. Even with this anticipated weakening, strong wind gusts are still possible. ...Central High Plains/Central Plains... A cold front is expected to push into the Upper Midwest and central Plains, likely extending from western WI southwestward into northeastern CO during the late afternoon. Moist upslope flow is anticipated into eastern WY/northeast CO behind this front, with the resulting convergence along the lee trough expected to result in thunderstorm initiation. Downstream environment characterized by strong buoyancy and at least moderate vertical shear will support supercell storm structures capable of very large hail and strong wind gusts. These storms are expected to continue eastward into NE during the evening. A strengthening low-level jet will lead to a reinvigoration of any ongoing storms and/or development of new storms, primarily across central and eastern NE. Given the presence of ample low-level moisture and steep mid-level lapse rates, large hail is probable with these storms. Isolated very large hail (i.e. greater than 2" in diameter) is possible. Dry mid-levels could also contribute to strong wind gusts. ...Upper Midwest... Ample low-level moisture and steep mid-level lapse rates will result in strong buoyancy ahead of the approaching cold front this morning across northern/central MN. Stable low-levels (below 850 mb) will likely limit storm strength but large hail and occasional strong gusts through the stable layer are possible. ...Northern Mid-Atlantic... Showers and thunderstorms will likely develop during the afternoon within the moist and diurnally destabilized air mass across the region. Vertical shear will be weak, leading to predominately disorganized, outflow-dominant multicells. Even so, the very moist air mass and steep low-level lapse rates support water-loaded downbursts capable of damaging wind gusts. ..Mosier/Nauslar.. 08/20/2019 Read more

WW 0601 Status Updates
STATUS FOR WATCH 0601 HAS NOT BEEN ISSUED YET Read more

WW 0601 Status Updates
STATUS FOR WATCH 0601 HAS NOT BEEN ISSUED YET Read more

WW 0601 Status Updates
STATUS FOR WATCH 0601 HAS NOT BEEN ISSUED YET Read more

MD 1805 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PORTIONS OF EASTERN ND INTO NORTHWESTERN MN
Mesoscale Discussion 1805 NWS Storm Prediction Center Norman OK 1122 PM CDT Mon Aug 19 2019 Areas affected...Portions of eastern ND into northwestern MN Concerning...Severe potential...Watch possible Valid 200422Z - 200615Z Probability of Watch Issuance...60 percent SUMMARY...An increasing threat for large hail and eventually damaging winds may require watch issuance in the next 1-2 hours. DISCUSSION...A pair of supercells has recently developed across north-central ND just to the east of a weak surface low. These storms are likely elevated at the moment owing to substantial convective inhibition, but they will pose an isolated large hail risk in the short term owing to moderate to strong elevated instability coupled with effective bulk shear around 50 kt. Additional storms are expected to develop along a southward-moving cold front in the vicinity of the international border in the next couple of hours. Upscale growth into a MCS appears probable, and a damaging wind threat may increase through the overnight. Watch issuance is possible in the next 1-2 hours depending on observational trends. ..Gleason/Grams.. 08/20/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DLH...FGF...BIS... LAT...LON 47919969 48360008 48770002 49059929 49039565 48709425 47659421 47069433 46499491 46449610 46509681 46719798 47559828 47919969 Read more

No watches are valid as of Tue Aug 20 04:07:01 UTC 2019.

MD 1804 CONCERNING SEVERE POTENTIAL...SEVERE THUNDERSTORM WATCH LIKELY FOR PORTIONS OF WESTERN/CENTRAL IA...FAR SOUTHEASTERN SD...FAR SOUTHWESTERN MN...AND FAR EASTERN NE
Mesoscale Discussion 1804 NWS Storm Prediction Center Norman OK 1105 PM CDT Mon Aug 19 2019 Areas affected...Portions of western/central IA...far southeastern SD...far southwestern MN...and far eastern NE Concerning...Severe potential...Severe Thunderstorm Watch likely Valid 200405Z - 200600Z Probability of Watch Issuance...80 percent SUMMARY...A threat for mainly large hail should increase over the next couple of hours as storms increase in coverage and intensity. Severe Thunderstorm Watch issuance is likely. DISCUSSION...A well-defined surface warm front extends eastward from a low over western SD across southern SD, roughly along the NE/IA border, and into southern IA. Warm air advection is occurring atop this front as a southwesterly low-level jet gradually strengthens late this evening. The VWP from KOAX has shown an increase in the 0-2 km layer over the past couple of hours, generally to around 30-35 kt above 1 km. Ascent associated with this low-level jet has encouraged elevated showers to develop across parts of northwestern IA, with a few recent lightning strikes noted with this activity. The 00Z sounding from OAX showed very steep mid-level lapse rates (around 8.6 C/km in the 700-500 mb layer) associated with an EML were present across this region. These lapse rates aloft coupled with ample low-level moisture are supporting moderate to very strong instability along and to the cool side of the front (MUCAPE of 2000-4500+) per latest mesoanalysis. Westerly winds strengthen with height through mid levels, and a subtle vorticity maximum along the NE/SD border maximum noted on water vapor may provide an additional source of lift to encourage at least scattered storm development. Around 40-50 kt of effective bulk shear will likely remain across this region through the overnight hours, which will support supercells initially. Given the large degree of elevated instability and strong shear present, robust updrafts appear likely. Large hail should be the primary hazard with initial storm development, with these storms likely remaining elevated above a near-surface stable layer to the cool side of the surface front. However, there is some potential for upscale growth into a MCS later tonight across parts of central IA, which could result in an eventual damaging wind threat materializing. Watch issuance is likely in the next couple of hours to address the initial large hail risk. ..Gleason/Grams.. 08/20/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MPX...DMX...FSD...OAX... LAT...LON 42999379 42499378 41829411 41399485 41359556 41539614 42029655 42799688 43569680 43709587 43659501 43559445 42999379 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0758 PM CDT Mon Aug 19 2019 Valid 200100Z - 201200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN IA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN MN... ...SUMMARY... Large hail and damaging gusts are expected late tonight across Iowa and northern Minnesota. ...01Z Update... ...Northern Plains into the Upper Midwest... A thunderstorm or two is still possible across ND and northeast SD as the front moves eastward tonight. Later tonight, increased storm coverage is anticipated along the front as it moves through northern MN. Moderate buoyancy and enhanced westerly flow aloft will result in an environment supportive of strong, organized updrafts. Potential for severe hail and strong wind gusts appears high enough to merit an increase in wind/hail probabilities and a Slight Risk. ...IA... Severe thunderstorms are still expected to develop late tonight amidst ample low-level moisture and a strong low-level jet. Large hail (isolated over 2" in diameter) will be the primary hazard with the initial development with the threat then shifting to strong wind gusts as upscale growth occurs. Primary change over this area was to pull the Slight Risk back farther west (to the MO River) to account for a greater potential for storms farther west. ..Mosier.. 08/20/2019 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0758 PM CDT Mon Aug 19 2019 Valid 200100Z - 201200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN IA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN MN... ...SUMMARY... Large hail and damaging gusts are expected late tonight across Iowa and northern Minnesota. ...01Z Update... ...Northern Plains into the Upper Midwest... A thunderstorm or two is still possible across ND and northeast SD as the front moves eastward tonight. Later tonight, increased storm coverage is anticipated along the front as it moves through northern MN. Moderate buoyancy and enhanced westerly flow aloft will result in an environment supportive of strong, organized updrafts. Potential for severe hail and strong wind gusts appears high enough to merit an increase in wind/hail probabilities and a Slight Risk. ...IA... Severe thunderstorms are still expected to develop late tonight amidst ample low-level moisture and a strong low-level jet. Large hail (isolated over 2" in diameter) will be the primary hazard with the initial development with the threat then shifting to strong wind gusts as upscale growth occurs. Primary change over this area was to pull the Slight Risk back farther west (to the MO River) to account for a greater potential for storms farther west. ..Mosier.. 08/20/2019 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0758 PM CDT Mon Aug 19 2019 Valid 200100Z - 201200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN IA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN MN... ...SUMMARY... Large hail and damaging gusts are expected late tonight across Iowa and northern Minnesota. ...01Z Update... ...Northern Plains into the Upper Midwest... A thunderstorm or two is still possible across ND and northeast SD as the front moves eastward tonight. Later tonight, increased storm coverage is anticipated along the front as it moves through northern MN. Moderate buoyancy and enhanced westerly flow aloft will result in an environment supportive of strong, organized updrafts. Potential for severe hail and strong wind gusts appears high enough to merit an increase in wind/hail probabilities and a Slight Risk. ...IA... Severe thunderstorms are still expected to develop late tonight amidst ample low-level moisture and a strong low-level jet. Large hail (isolated over 2" in diameter) will be the primary hazard with the initial development with the threat then shifting to strong wind gusts as upscale growth occurs. Primary change over this area was to pull the Slight Risk back farther west (to the MO River) to account for a greater potential for storms farther west. ..Mosier.. 08/20/2019 Read more

MD 1803 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF SOUTHERN ILLINOIS AND VICINITY
Mesoscale Discussion 1803 NWS Storm Prediction Center Norman OK 0707 PM CDT Mon Aug 19 2019 Areas affected...portions of southern Illinois and vicinity Concerning...Severe potential...Watch unlikely Valid 200007Z - 200130Z Probability of Watch Issuance...5 percent SUMMARY...Thunderstorms continue to develop across portions of southern Illinois and vicinity with large hail and damaging wind gusts possible. A watch is unlikely. DISCUSSION...A hot, moist, and unstable airmass is across the mid Mississippi Valley with surface temperatures in the 90s F and dewpoints 70+ F. MLCAPE of 3000-4500 J/kg has resulted and as convective temperatures have been breached, thunderstorms have developed this evening. While flow/shear are rather weak across the area, the large buoyancy will help compensate with marginally large hail possible. Water-loaded downdrafts coupled with steep low-level lapse rates may result in damaging wind gusts as well. Storms will likely weaken after sunset and given the lack of organization/shear, the severe threat should remain isolated and marginal. ..Nauslar/Grams.. 08/20/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...IND...PAH...ILX...LSX... LAT...LON 38479044 38919030 39408965 39628902 39748826 39638771 39358726 38748743 38228813 37898920 37778986 38219038 38479044 Read more

MD 1802 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF WESTERN/SOUTHERN ND INTO NORTHERN SD
Mesoscale Discussion 1802 NWS Storm Prediction Center Norman OK 0606 PM CDT Mon Aug 19 2019 Areas affected...Portions of western/southern ND into northern SD Concerning...Severe potential...Watch unlikely Valid 192306Z - 200100Z Probability of Watch Issuance...20 percent SUMMARY...An isolated large hail and wind threat should increase this evening. A watch will probably not be needed unless greater than expected storm coverage occurs. DISCUSSION...A surface trough is located across western ND at 23Z per observations. Weak low-level convergence along this boundary has fostered a gradually deepening cumulus field across this region, and convective initiation may occur over the next couple of hours (through 02Z). The lack of more obvious large-scale ascent suggests overall storm coverage will probably remain isolated. Low-level moisture return is occurring across the central into northern Plains early this evening, with upper 60s to lower 70s surface dewpoints extending as far north as the ND/SD border region as of 23Z. Modestly steepened mid-level lapse rates have overspread this region from the higher terrain of the northern Rockies/High Plains, which combined with the returning low-level moisture and strong diurnal heating is supporting weak to moderate instability along and just ahead of the surface trough. RAP forecast soundings across western ND show a veering wind profile through about 3 km, with generally westerly winds strengthening with height through the remainder of the troposphere. Resultant effective bulk shear of 45-50 kt will easily support supercells with an associated large hail threat. Some severe wind gusts may also occur where low-level lapse rates have become steepened. Current expectations are for a relatively greater severe threat to develop across southwestern ND initially, as somewhat greater low-level moisture and stronger instability should be present. There is some potential for a supercell or two to move east-southeastward through the evening along the ND/SD border along an instability gradient. Overall storm coverage is still somewhat uncertain, and a watch will probably not be issued unless at least a few supercells develop. ..Gleason/Grams.. 08/19/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ABR...BIS...UNR... LAT...LON 45890317 46860339 48290315 49060286 49020145 48030148 47100138 46520064 46010031 45590046 45280099 45310174 45520262 45890317 Read more

MD 1802 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF WESTERN/SOUTHERN ND INTO NORTHERN SD
Mesoscale Discussion 1802 NWS Storm Prediction Center Norman OK 0606 PM CDT Mon Aug 19 2019 Areas affected...Portions of western/southern ND into northern SD Concerning...Severe potential...Watch unlikely Valid 192306Z - 200100Z Probability of Watch Issuance...20 percent SUMMARY...An isolated large hail and wind threat should increase this evening. A watch will probably not be needed unless greater than expected storm coverage occurs. DISCUSSION...A surface trough is located across western ND at 23Z per observations. Weak low-level convergence along this boundary has fostered a gradually deepening cumulus field across this region, and convective initiation may occur over the next couple of hours (through 02Z). The lack of more obvious large-scale ascent suggests overall storm coverage will probably remain isolated. Low-level moisture return is occurring across the central into northern Plains early this evening, with upper 60s to lower 70s surface dewpoints extending as far north as the ND/SD border region as of 23Z. Modestly steepened mid-level lapse rates have overspread this region from the higher terrain of the northern Rockies/High Plains, which combined with the returning low-level moisture and strong diurnal heating is supporting weak to moderate instability along and just ahead of the surface trough. RAP forecast soundings across western ND show a veering wind profile through about 3 km, with generally westerly winds strengthening with height through the remainder of the troposphere. Resultant effective bulk shear of 45-50 kt will easily support supercells with an associated large hail threat. Some severe wind gusts may also occur where low-level lapse rates have become steepened. Current expectations are for a relatively greater severe threat to develop across southwestern ND initially, as somewhat greater low-level moisture and stronger instability should be present. There is some potential for a supercell or two to move east-southeastward through the evening along the ND/SD border along an instability gradient. Overall storm coverage is still somewhat uncertain, and a watch will probably not be issued unless at least a few supercells develop. ..Gleason/Grams.. 08/19/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ABR...BIS...UNR... LAT...LON 45890317 46860339 48290315 49060286 49020145 48030148 47100138 46520064 46010031 45590046 45280099 45310174 45520262 45890317 Read more