Storm Prediction Center

No Mesoscale Discussions are in effect as of Fri Jul 17 08:01:02 UTC 2026.

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0255 AM CDT Fri Jul 17 2026 Valid 201200Z - 251200Z ...DISCUSSION... ...Days 4-6/Mon-Wed -- Great Lakes/Midwest to the Mid-Atlantic/Northeast... A shortwave upper trough initially over the Canadian Prairies and northern Plains will develop east/southeast across the Upper Midwest/Great Lakes on Monday, then the Ohio Valley and Mid-Atlantic vicinity on Tuesday. Meanwhile, another upper shortwave trough will develop across the Great Lakes to the Northeast/Mid-Atlantic on Wednesday. These features will support enhancement of mid/upper level flow as a surface low tracks across Ontario/Quebec and New England during this time. A trailing cold front will likewise progress east/southeast over this three day period, with a very moist and unstable airmass present ahead of the front. This overall pattern will likely bring multiple days of severe storm potential from the Upper Midwest/Great Lakes to portions of the Ohio Valley, Northeast and Mid-Atlantic vicinity Monday through Wednesday, necessitating severe probabilities. While these areas may shift some over the coming day as the timing of mesoscale features and influence of prior days convection becomes more clear, these general regions are most likely to see at least isolated to widely scattered damaging wind potential as the upper trough and surface cold front sweep across the area. ...Days 7-8/Thu-Fri... Surface high pressure building behind the aforementioned surface cold front will become centered over the Midwest late in the forecast period. Upper troughing will persist across the East while an amplified upper ridge remains oriented from TX to MT. Overall, severe potential appears low late in the forecast period. Read more

MD 1640 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR EDWARDS PLATEAU OF TX
Mesoscale Discussion 1640 NWS Storm Prediction Center Norman OK 0202 AM CDT Fri Jul 17 2026 Areas affected...Edwards Plateau of TX Concerning...Severe potential...Watch unlikely Valid 170702Z - 170800Z Probability of Watch Issuance...20 percent SUMMARY...The environment within a mesoscale area may continue to support a couple of weak supercells during the overnight. A brief tornado is possible. DISCUSSION...KDFX radar imagery at 0700 UTC shows several distinct updrafts within a southwest to northeast-oriented thunderstorm cluster (i.e., evident via echo top imagery). A stationary mid-level low over the Permian Basin will promote a persistent and unchanging flow regime across the Edwards Plateau and Hill Country through tonight. KDFX VAD data has shown some modest enhancement to easterly to southerly flow within the surface to 2 km layer during the past 3 hours (i.e., strengthening of 5-10 kt). Furthermore, the presence of a very moist boundary layer (lower to mid 70s F surface dewpoints) and adequate buoyancy may combine with the enlarged low-level hodographs to support intermittent supercell structures for the next several hours. Accompanying this episodic intensification of a couple of storms into supercells, a brief tornado cannot be ruled out. Will continue to monitor mesoscale trends. ..Smith.. 07/17/2026 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...EWX...SJT... LAT...LON 29920076 30340064 30929953 30849913 30619902 30299906 29610047 29650069 29920076 MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0150 AM CDT Fri Jul 17 2026 Valid 181200Z - 191200Z ...Synopsis... Between a midlevel trough moving across BC and an expansive large-scale ridge over the central/western CONUS, enhanced deep-layer south-southwesterly flow will overspread a deep/dry boundary layer (around 10-15 percent RH) in the lee of the northern Sierra and Cascades. These dry conditions combined with around 15 mph sustained west-southwesterly surface winds will favor elevated fire-weather conditions during the afternoon, given dry/receptive fuels. ..Weinman.. 07/17/2026 ...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 0150 AM CDT Fri Jul 17 2026 Valid 181200Z - 191200Z ...Synopsis... Between a midlevel trough moving across BC and an expansive large-scale ridge over the central/western CONUS, enhanced deep-layer south-southwesterly flow will overspread a deep/dry boundary layer (around 10-15 percent RH) in the lee of the northern Sierra and Cascades. These dry conditions combined with around 15 mph sustained west-southwesterly surface winds will favor elevated fire-weather conditions during the afternoon, given dry/receptive fuels. ..Weinman.. 07/17/2026 ...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 0149 AM CDT Fri Jul 17 2026 Valid 171200Z - 181200Z ...Synopsis... A midlevel low will move northward along the Pacific Northwest coast today. Between this feature and an expansive upper ridge over the Rockies and Great Basin, a belt of enhanced south-southwesterly low/mid-level flow will overspread the northern Great Basin and Northwest. Downslope-enhanced warming/drying in the lee of the northern Cascades and Columbia Basin will result in deep boundary-layer mixing (10-15 percent RH). These warm/dry conditions combined with around 15 mph sustained southwesterly winds atop receptive fuels will yield elevated fire-weather conditions during the afternoon. ..Weinman.. 07/17/2026 ...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 0149 AM CDT Fri Jul 17 2026 Valid 171200Z - 181200Z ...Synopsis... A midlevel low will move northward along the Pacific Northwest coast today. Between this feature and an expansive upper ridge over the Rockies and Great Basin, a belt of enhanced south-southwesterly low/mid-level flow will overspread the northern Great Basin and Northwest. Downslope-enhanced warming/drying in the lee of the northern Cascades and Columbia Basin will result in deep boundary-layer mixing (10-15 percent RH). These warm/dry conditions combined with around 15 mph sustained southwesterly winds atop receptive fuels will yield elevated fire-weather conditions during the afternoon. ..Weinman.. 07/17/2026 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0126 AM CDT Fri Jul 17 2026 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF SC/NC INTO SOUTHEAST VA... ...SUMMARY... Isolated to widely scattered strong to severe thunderstorms may pose a risk for damaging wind gusts across portions of the southern Appalachians to the coastal Carolinas/southeast Virginia vicinity on Sunday. ...Southern Appalachians to Coastal Carolinas/Southeast Virginia... Upper troughing will persist across the eastern U.S. on Sunday. A couple of embedded vorticity maxima within the base of the trough will move across the southern Appalachians/southern Mid-Atlantic region through early evening. Deep layer westerly flow will remain modest, but a very moist and strongly unstable airmass will be in place. Large instability coupled with PW values near 2 inches will support isolated severe storms capable of damaging wind gusts. A corridor of relative greater risk may develop from southeast VA into eastern NC near a stalled frontal boundary and where vertical shear may be modestly stronger (25 kt effective shear). ...Eastern ND into northern MN... Northwesterly flow aloft will strengthen on Sunday/Sunday night as upper ridging flattens a bit as an upper shortwave trough emerges over the Canadian Prairies. Vertically veering wind profiles will foster 30+ kt effective shear magnitudes and a few organized cells could develop. Some potential for capping could limit storm coverage, but any storm that develops could be a higher-based supercell capable of severe hail and strong gusts. ..Leitman.. 07/17/2026 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0126 AM CDT Fri Jul 17 2026 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF SC/NC INTO SOUTHEAST VA... ...SUMMARY... Isolated to widely scattered strong to severe thunderstorms may pose a risk for damaging wind gusts across portions of the southern Appalachians to the coastal Carolinas/southeast Virginia vicinity on Sunday. ...Southern Appalachians to Coastal Carolinas/Southeast Virginia... Upper troughing will persist across the eastern U.S. on Sunday. A couple of embedded vorticity maxima within the base of the trough will move across the southern Appalachians/southern Mid-Atlantic region through early evening. Deep layer westerly flow will remain modest, but a very moist and strongly unstable airmass will be in place. Large instability coupled with PW values near 2 inches will support isolated severe storms capable of damaging wind gusts. A corridor of relative greater risk may develop from southeast VA into eastern NC near a stalled frontal boundary and where vertical shear may be modestly stronger (25 kt effective shear). ...Eastern ND into northern MN... Northwesterly flow aloft will strengthen on Sunday/Sunday night as upper ridging flattens a bit as an upper shortwave trough emerges over the Canadian Prairies. Vertically veering wind profiles will foster 30+ kt effective shear magnitudes and a few organized cells could develop. Some potential for capping could limit storm coverage, but any storm that develops could be a higher-based supercell capable of severe hail and strong gusts. ..Leitman.. 07/17/2026 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0126 AM CDT Fri Jul 17 2026 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF SC/NC INTO SOUTHEAST VA... ...SUMMARY... Isolated to widely scattered strong to severe thunderstorms may pose a risk for damaging wind gusts across portions of the southern Appalachians to the coastal Carolinas/southeast Virginia vicinity on Sunday. ...Southern Appalachians to Coastal Carolinas/Southeast Virginia... Upper troughing will persist across the eastern U.S. on Sunday. A couple of embedded vorticity maxima within the base of the trough will move across the southern Appalachians/southern Mid-Atlantic region through early evening. Deep layer westerly flow will remain modest, but a very moist and strongly unstable airmass will be in place. Large instability coupled with PW values near 2 inches will support isolated severe storms capable of damaging wind gusts. A corridor of relative greater risk may develop from southeast VA into eastern NC near a stalled frontal boundary and where vertical shear may be modestly stronger (25 kt effective shear). ...Eastern ND into northern MN... Northwesterly flow aloft will strengthen on Sunday/Sunday night as upper ridging flattens a bit as an upper shortwave trough emerges over the Canadian Prairies. Vertically veering wind profiles will foster 30+ kt effective shear magnitudes and a few organized cells could develop. Some potential for capping could limit storm coverage, but any storm that develops could be a higher-based supercell capable of severe hail and strong gusts. ..Leitman.. 07/17/2026 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1232 AM CDT Fri Jul 17 2026 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE OHIO VALLEY INTO THE MID-ATLANTIC AND SOUTHERN NEW ENGLAND... ...SUMMARY... Severe thunderstorms are expected across portions of the Ohio Valley and Lower Great Lakes into the Mid-Atlantic, mainly Saturday afternoon into the evening. Some threat may linger into late Saturday night. ...Ohio Valley/Great Lakes to Mid-Atlantic... An upper shortwave trough over the Great Lakes is expected to amplify as it pivots east across the Ohio Valley and into the Mid-Atlantic/Northeast region on Saturday. As this occurs, deep-layer flow will increase, with guidance suggesting 850-500 mb flow in the 40-50 kt range will be common. At the surface, low pressure will deepen as it shifts east across Ontario and Quebec. A trailing cold front will develop south/southeast across the region during the late afternoon into nighttime hours. Ahead of the front, a quasi-warm front is expect to be oriented across the Mid-Atlantic and will lift northward through the day within a strong warm advection regime. Initially modest boundary layer moisture across PA, northward through the Hudson Valley will rapidly moisten ahead of the approaching cold front. A corridor of moderate to strong destabilization is expected from the Mid-MS and OH Valleys into the Mid-Atlantic. Convection may be ongoing across parts of PA/NY into the Mid-Atlantic Saturday morning within the strong warm advection regime. Some potential for an initial round of severe storms could accompany this activity, especially near the surface warm front. Additional thunderstorms will develop during the afternoon near a prefrontal trough and along higher terrain in VA/NC. Vertical shear will be somewhat less with southward extent, but scattered cells and clusters will develop east through early evening posing a risk for damaging wind gusts. Supercell wind profiles are apparent in forecast soundings and a tornado risk is also possible, especially near the surface warm front and prefrontal trough where 0-1 km SRH will be maximized. Substantial thunderstorm development is also expected within a second corridor near the surface cold front from southern Quebec into MI/IN/IL by midday. Surface dewpoints in the mid 60s to low 70s F will provide ample support for 2000+ J/kg MLCAPE from the Mid MS Valley toward western PA. Organized cells and line segments will pose a risk for damaging wind swaths across the region. Some uncertainty still exists due to effects from morning convection and possible impacts from persistent smoke across parts of the Mid-Atlantic. However, the overall pattern supports a broad area of severe potential, with several swaths of damaging winds and a few tornadoes expected. ...MT/ID... A plume of steep midlevel lapse rates will overspread the area on the southern periphery of stronger southwesterly flow aloft as an shortwave upper trough shifts east across the Canadian Rockies. Ample midlevel moisture amid steep lapse rates will foster MLCAPE near 1000 J/kg. Forecast soundings also indicate elongated/straight hodographs amid 35 kt effective shear magnitudes. Isolated organized cells will pose a risk for hail and strong wind gusts through early evening. ..Leitman.. 07/17/2026 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1232 AM CDT Fri Jul 17 2026 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE OHIO VALLEY INTO THE MID-ATLANTIC AND SOUTHERN NEW ENGLAND... ...SUMMARY... Severe thunderstorms are expected across portions of the Ohio Valley and Lower Great Lakes into the Mid-Atlantic, mainly Saturday afternoon into the evening. Some threat may linger into late Saturday night. ...Ohio Valley/Great Lakes to Mid-Atlantic... An upper shortwave trough over the Great Lakes is expected to amplify as it pivots east across the Ohio Valley and into the Mid-Atlantic/Northeast region on Saturday. As this occurs, deep-layer flow will increase, with guidance suggesting 850-500 mb flow in the 40-50 kt range will be common. At the surface, low pressure will deepen as it shifts east across Ontario and Quebec. A trailing cold front will develop south/southeast across the region during the late afternoon into nighttime hours. Ahead of the front, a quasi-warm front is expect to be oriented across the Mid-Atlantic and will lift northward through the day within a strong warm advection regime. Initially modest boundary layer moisture across PA, northward through the Hudson Valley will rapidly moisten ahead of the approaching cold front. A corridor of moderate to strong destabilization is expected from the Mid-MS and OH Valleys into the Mid-Atlantic. Convection may be ongoing across parts of PA/NY into the Mid-Atlantic Saturday morning within the strong warm advection regime. Some potential for an initial round of severe storms could accompany this activity, especially near the surface warm front. Additional thunderstorms will develop during the afternoon near a prefrontal trough and along higher terrain in VA/NC. Vertical shear will be somewhat less with southward extent, but scattered cells and clusters will develop east through early evening posing a risk for damaging wind gusts. Supercell wind profiles are apparent in forecast soundings and a tornado risk is also possible, especially near the surface warm front and prefrontal trough where 0-1 km SRH will be maximized. Substantial thunderstorm development is also expected within a second corridor near the surface cold front from southern Quebec into MI/IN/IL by midday. Surface dewpoints in the mid 60s to low 70s F will provide ample support for 2000+ J/kg MLCAPE from the Mid MS Valley toward western PA. Organized cells and line segments will pose a risk for damaging wind swaths across the region. Some uncertainty still exists due to effects from morning convection and possible impacts from persistent smoke across parts of the Mid-Atlantic. However, the overall pattern supports a broad area of severe potential, with several swaths of damaging winds and a few tornadoes expected. ...MT/ID... A plume of steep midlevel lapse rates will overspread the area on the southern periphery of stronger southwesterly flow aloft as an shortwave upper trough shifts east across the Canadian Rockies. Ample midlevel moisture amid steep lapse rates will foster MLCAPE near 1000 J/kg. Forecast soundings also indicate elongated/straight hodographs amid 35 kt effective shear magnitudes. Isolated organized cells will pose a risk for hail and strong wind gusts through early evening. ..Leitman.. 07/17/2026 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1232 AM CDT Fri Jul 17 2026 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE OHIO VALLEY INTO THE MID-ATLANTIC AND SOUTHERN NEW ENGLAND... ...SUMMARY... Severe thunderstorms are expected across portions of the Ohio Valley and Lower Great Lakes into the Mid-Atlantic, mainly Saturday afternoon into the evening. Some threat may linger into late Saturday night. ...Ohio Valley/Great Lakes to Mid-Atlantic... An upper shortwave trough over the Great Lakes is expected to amplify as it pivots east across the Ohio Valley and into the Mid-Atlantic/Northeast region on Saturday. As this occurs, deep-layer flow will increase, with guidance suggesting 850-500 mb flow in the 40-50 kt range will be common. At the surface, low pressure will deepen as it shifts east across Ontario and Quebec. A trailing cold front will develop south/southeast across the region during the late afternoon into nighttime hours. Ahead of the front, a quasi-warm front is expect to be oriented across the Mid-Atlantic and will lift northward through the day within a strong warm advection regime. Initially modest boundary layer moisture across PA, northward through the Hudson Valley will rapidly moisten ahead of the approaching cold front. A corridor of moderate to strong destabilization is expected from the Mid-MS and OH Valleys into the Mid-Atlantic. Convection may be ongoing across parts of PA/NY into the Mid-Atlantic Saturday morning within the strong warm advection regime. Some potential for an initial round of severe storms could accompany this activity, especially near the surface warm front. Additional thunderstorms will develop during the afternoon near a prefrontal trough and along higher terrain in VA/NC. Vertical shear will be somewhat less with southward extent, but scattered cells and clusters will develop east through early evening posing a risk for damaging wind gusts. Supercell wind profiles are apparent in forecast soundings and a tornado risk is also possible, especially near the surface warm front and prefrontal trough where 0-1 km SRH will be maximized. Substantial thunderstorm development is also expected within a second corridor near the surface cold front from southern Quebec into MI/IN/IL by midday. Surface dewpoints in the mid 60s to low 70s F will provide ample support for 2000+ J/kg MLCAPE from the Mid MS Valley toward western PA. Organized cells and line segments will pose a risk for damaging wind swaths across the region. Some uncertainty still exists due to effects from morning convection and possible impacts from persistent smoke across parts of the Mid-Atlantic. However, the overall pattern supports a broad area of severe potential, with several swaths of damaging winds and a few tornadoes expected. ...MT/ID... A plume of steep midlevel lapse rates will overspread the area on the southern periphery of stronger southwesterly flow aloft as an shortwave upper trough shifts east across the Canadian Rockies. Ample midlevel moisture amid steep lapse rates will foster MLCAPE near 1000 J/kg. Forecast soundings also indicate elongated/straight hodographs amid 35 kt effective shear magnitudes. Isolated organized cells will pose a risk for hail and strong wind gusts through early evening. ..Leitman.. 07/17/2026 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Fri Jul 17 2026 Valid 171200Z - 181200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF THE NORTHERN ROCKIES...GREAT LAKES AND OHIO VALLEY TO THE SOUTHERN APPALACHIANS.... ...SUMMARY... Strong to potentially severe storms are possible today across parts of western Montana and northern Idaho, and also across parts of the Upper Midwest and northern Great Lakes. More isolated strong to severe storms with damaging gusts are possible over parts of the Ohio Valley and southern Appalachians. ...Northern Rockies and Adjacent Plains... An upper low over the Pacific Northwest is forecast to lift slowly northward as an expansive upper ridge continues to build across the western US. East of the low, a broad area of monsoon moisture will persist over much of the Rocky Mountains. Weak ascent on the periphery of the upper low and diurnal heating across the higher terrain should allow for scattered thunderstorm development through the afternoon. While displaced from the core of the stronger flow aloft as the upper low drifts to the north, sufficient effective shear of 25-35 kt will exist for occasional storm organization. Isolated hail and severe gusts could accompany the strongest storms into the evening across ID and western MT. ...Upper Midwest and northern Great Lakes... An upper trough initially over AB/SK will move southward into the northern Great Lakes by early Saturday. A belt of stronger mid-level flow accompanying the upper trough will aid in deepening a surface low as it moves into western ON. A warm front will lift north with the deepening low over the Upper Midwest. A cold front trailing the surface low will provide a focus for thunderstorm development over northern MN, WI and the UP of MI this afternoon and evening. A cluster of elevated thunderstorms is likely to be ongoing early in the period near or just across the international border. These storms could reinvigorate with a risk for some damaging gusts and hail, though confidence in the convective evolution is low. Later in the day ahead of the cold front, moderate buoyancy and sufficient deep-layer shear will conditionally support a threat for isolated supercells or organized multicell clusters, with a threat of hail and damaging winds. Any persistent supercell may also pose at least a brief tornado threat, especially in closer proximity to the surface low and warm front where low-level shear will be maximized. As the main upper trough continues to southeast one or more clusters of strong to severe storms may persist into the overnight along the warm front. However, confidence in this scenario is lower owing to the prior convection and uncertainties of diurnal development along the cold front. Still, a strengthening wind field and ample moisture could support a risk for damaging winds into northern Lower MI overnight. ...OH Valley to the southern Appalachians... A warm and seasonably moist air mass will support moderate to locally strong buoyancy beneath the upper ridge from the OH valley toward the Southeast and southern Appalachians. A weak, convectively enhanced sub-tropical disturbance moving northward and the higher terrain should focus more widespread diurnal thunderstorm activity from portions of IN/OH, into eastern KY/TN, the western Carolinas and northern GA. Despite weak deep-layer shear below 20 kt, moderate to strong MLCAPE (2000-3000 J/kg) and PWATS exceeding 2 inches may allow for sporadic damaging gusts with any stronger multicell clusters. ...FL... CAM guidance shows vigorous storm development just offshore of the FL Gulf Coast Friday morning, in association with a weak midlevel trough/low. Additional storm development is expected by afternoon across much of the peninsula. Large buoyancy and high PWATs suggest localized strong to severe gusts cannot be ruled out near the coast and inland this afternoon. ..Lyons/Weinman.. 07/17/2026 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Fri Jul 17 2026 Valid 171200Z - 181200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF THE NORTHERN ROCKIES...GREAT LAKES AND OHIO VALLEY TO THE SOUTHERN APPALACHIANS.... ...SUMMARY... Strong to potentially severe storms are possible today across parts of western Montana and northern Idaho, and also across parts of the Upper Midwest and northern Great Lakes. More isolated strong to severe storms with damaging gusts are possible over parts of the Ohio Valley and southern Appalachians. ...Northern Rockies and Adjacent Plains... An upper low over the Pacific Northwest is forecast to lift slowly northward as an expansive upper ridge continues to build across the western US. East of the low, a broad area of monsoon moisture will persist over much of the Rocky Mountains. Weak ascent on the periphery of the upper low and diurnal heating across the higher terrain should allow for scattered thunderstorm development through the afternoon. While displaced from the core of the stronger flow aloft as the upper low drifts to the north, sufficient effective shear of 25-35 kt will exist for occasional storm organization. Isolated hail and severe gusts could accompany the strongest storms into the evening across ID and western MT. ...Upper Midwest and northern Great Lakes... An upper trough initially over AB/SK will move southward into the northern Great Lakes by early Saturday. A belt of stronger mid-level flow accompanying the upper trough will aid in deepening a surface low as it moves into western ON. A warm front will lift north with the deepening low over the Upper Midwest. A cold front trailing the surface low will provide a focus for thunderstorm development over northern MN, WI and the UP of MI this afternoon and evening. A cluster of elevated thunderstorms is likely to be ongoing early in the period near or just across the international border. These storms could reinvigorate with a risk for some damaging gusts and hail, though confidence in the convective evolution is low. Later in the day ahead of the cold front, moderate buoyancy and sufficient deep-layer shear will conditionally support a threat for isolated supercells or organized multicell clusters, with a threat of hail and damaging winds. Any persistent supercell may also pose at least a brief tornado threat, especially in closer proximity to the surface low and warm front where low-level shear will be maximized. As the main upper trough continues to southeast one or more clusters of strong to severe storms may persist into the overnight along the warm front. However, confidence in this scenario is lower owing to the prior convection and uncertainties of diurnal development along the cold front. Still, a strengthening wind field and ample moisture could support a risk for damaging winds into northern Lower MI overnight. ...OH Valley to the southern Appalachians... A warm and seasonably moist air mass will support moderate to locally strong buoyancy beneath the upper ridge from the OH valley toward the Southeast and southern Appalachians. A weak, convectively enhanced sub-tropical disturbance moving northward and the higher terrain should focus more widespread diurnal thunderstorm activity from portions of IN/OH, into eastern KY/TN, the western Carolinas and northern GA. Despite weak deep-layer shear below 20 kt, moderate to strong MLCAPE (2000-3000 J/kg) and PWATS exceeding 2 inches may allow for sporadic damaging gusts with any stronger multicell clusters. ...FL... CAM guidance shows vigorous storm development just offshore of the FL Gulf Coast Friday morning, in association with a weak midlevel trough/low. Additional storm development is expected by afternoon across much of the peninsula. Large buoyancy and high PWATs suggest localized strong to severe gusts cannot be ruled out near the coast and inland this afternoon. ..Lyons/Weinman.. 07/17/2026 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Fri Jul 17 2026 Valid 171200Z - 181200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF THE NORTHERN ROCKIES...GREAT LAKES AND OHIO VALLEY TO THE SOUTHERN APPALACHIANS.... ...SUMMARY... Strong to potentially severe storms are possible today across parts of western Montana and northern Idaho, and also across parts of the Upper Midwest and northern Great Lakes. More isolated strong to severe storms with damaging gusts are possible over parts of the Ohio Valley and southern Appalachians. ...Northern Rockies and Adjacent Plains... An upper low over the Pacific Northwest is forecast to lift slowly northward as an expansive upper ridge continues to build across the western US. East of the low, a broad area of monsoon moisture will persist over much of the Rocky Mountains. Weak ascent on the periphery of the upper low and diurnal heating across the higher terrain should allow for scattered thunderstorm development through the afternoon. While displaced from the core of the stronger flow aloft as the upper low drifts to the north, sufficient effective shear of 25-35 kt will exist for occasional storm organization. Isolated hail and severe gusts could accompany the strongest storms into the evening across ID and western MT. ...Upper Midwest and northern Great Lakes... An upper trough initially over AB/SK will move southward into the northern Great Lakes by early Saturday. A belt of stronger mid-level flow accompanying the upper trough will aid in deepening a surface low as it moves into western ON. A warm front will lift north with the deepening low over the Upper Midwest. A cold front trailing the surface low will provide a focus for thunderstorm development over northern MN, WI and the UP of MI this afternoon and evening. A cluster of elevated thunderstorms is likely to be ongoing early in the period near or just across the international border. These storms could reinvigorate with a risk for some damaging gusts and hail, though confidence in the convective evolution is low. Later in the day ahead of the cold front, moderate buoyancy and sufficient deep-layer shear will conditionally support a threat for isolated supercells or organized multicell clusters, with a threat of hail and damaging winds. Any persistent supercell may also pose at least a brief tornado threat, especially in closer proximity to the surface low and warm front where low-level shear will be maximized. As the main upper trough continues to southeast one or more clusters of strong to severe storms may persist into the overnight along the warm front. However, confidence in this scenario is lower owing to the prior convection and uncertainties of diurnal development along the cold front. Still, a strengthening wind field and ample moisture could support a risk for damaging winds into northern Lower MI overnight. ...OH Valley to the southern Appalachians... A warm and seasonably moist air mass will support moderate to locally strong buoyancy beneath the upper ridge from the OH valley toward the Southeast and southern Appalachians. A weak, convectively enhanced sub-tropical disturbance moving northward and the higher terrain should focus more widespread diurnal thunderstorm activity from portions of IN/OH, into eastern KY/TN, the western Carolinas and northern GA. Despite weak deep-layer shear below 20 kt, moderate to strong MLCAPE (2000-3000 J/kg) and PWATS exceeding 2 inches may allow for sporadic damaging gusts with any stronger multicell clusters. ...FL... CAM guidance shows vigorous storm development just offshore of the FL Gulf Coast Friday morning, in association with a weak midlevel trough/low. Additional storm development is expected by afternoon across much of the peninsula. Large buoyancy and high PWATs suggest localized strong to severe gusts cannot be ruled out near the coast and inland this afternoon. ..Lyons/Weinman.. 07/17/2026 Read more

WW 0491 Status Updates
STATUS REPORT ON WW 491 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 60 ESE MOT TO 25 SE DVL TO 20 NNE JMS. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1639 ..MEAD..07/17/26 ATTN...WFO...FGF...BIS... STATUS REPORT FOR WS 491 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NDC027-031-103-170440- ND . NORTH DAKOTA COUNTIES INCLUDED ARE EDDY FOSTER WELLS THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 0491 Status Updates
STATUS REPORT ON WW 491 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 60 ESE MOT TO 25 SE DVL TO 20 NNE JMS. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1639 ..MEAD..07/17/26 ATTN...WFO...FGF...BIS... STATUS REPORT FOR WS 491 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NDC027-031-103-170440- ND . NORTH DAKOTA COUNTIES INCLUDED ARE EDDY FOSTER WELLS THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 491 SEVERE TSTM ND 162320Z - 170500Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 491 NWS Storm Prediction Center Norman OK 620 PM CDT Thu Jul 16 2026 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Northeast North Dakota * Effective this Thursday night from 620 PM until Midnight CDT. * Primary threats include... Scattered large hail and isolated very large hail events to 2 inches in diameter possible Scattered damaging wind gusts to 70 mph possible SUMMARY...A cluster of thunderstorms will likely develop this evening and track eastward across the watch area. The strongest cells will pose a risk of large hail and damaging wind gusts. The severe thunderstorm watch area is approximately along and 60 statute miles north and south of a line from 55 miles west of Devils Lake ND to 15 miles north northeast of Grand Forks ND. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU1). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && AVIATION...A few severe thunderstorms with hail surface and aloft to 2 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 28030. ...Hart Read more

MD 1638 CONCERNING SEVERE THUNDERSTORM WATCH 491... FOR NORTH-CENTRAL NORTH DAKOTA
Mesoscale Discussion 1638 NWS Storm Prediction Center Norman OK 0925 PM CDT Thu Jul 16 2026 Areas affected...north-central North Dakota Concerning...Severe Thunderstorm Watch 491... Valid 170225Z - 170400Z The severe weather threat for Severe Thunderstorm Watch 491 continues. SUMMARY...The threat for large hail and a brief tornado or two continues across western portions of the watch area. DISCUSSION...As of 2:15Z, volumetric radar data indicates a supercell over southern Benson County moving at 325/20 kt. The storm has remained anchored to a boundary that extends to the south-southwest with a recent tornado report near Maddock. Latest objective analysis indicates 0-3-km CAPE as high as 150-175 J/kg along the boundary, and while low-level shear is not overly strong, the storm-boundary interaction will support a continued risk for a brief tornado or two for the next 1-2 hours. Despite echo tops approaching 65 kft at times, large hail has remained limited. However, given the persistent supercell structures, at least marginally severe hail will remain a threat. ..Mead.. 07/17/2026 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FGF...BIS... LAT...LON 47909996 48229997 48529960 48389878 47809862 47569874 47499960 47909996 MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN Read more