Aggregator

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0745 AM CDT Sat Jul 19 2025 Valid 191300Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS...MIDWEST/GREAT LAKES...AND VIRGINIA/NORTH CAROLINA... ...SUMMARY... Scattered damaging winds are possible today across parts of the Midwest/Great Lakes and southern Mid-Atlantic. Scattered large to very large hail and severe gusts are possible across the northern/central Plains during the late afternoon and evening. ...Midwest/Great Lakes... A small thunderstorm cluster ongoing this morning across southern/eastern IA should continue to track east-southeastward along an instability gradient across parts of northern MO, IL, and perhaps IN into at least the early afternoon. With sufficient organization and evidence of a cold pool, this cluster may pose a threat for strong to locally damaging winds. Reference Mesoscale Discussion 1719 for more details. The potential for additional strong to severe thunderstorms across the Midwest and Great Lakes regions remains somewhat unclear given rather nebulous/weak forcing aloft. Stronger westerly mid-level flow associated with upper troughing over eastern Canada should tend to remain mostly displaced to the north of the surface warm sector. Still, daytime heating of a moist low-level airmass will likely encourage the development of moderate to locally strong instability by early to mid afternoon away from convective influences. Somewhat stronger flow aloft and related deep-layer shear should be present this afternoon across Lower MI. A mix of multicells and marginal supercells may spread eastward from ongoing activity across WI, or develop separately over this area while posing a threat for isolated severe hail and damaging winds. Farther south into the Midwest/OH Valley, weaker deep-layer shear and the bulk of convection-allowing model guidance suggests that multicell clusters should be the main convective mode. One or more of these clusters will probably persist from the ongoing activity this morning, or develop this afternoon along its outflow. Scattered severe/damaging winds will likely be the main threat as these thunderstorms move east-southeastward this afternoon into early evening across much of the OH Valley/Midwest. This convection should eventually weaken this evening as it encounters a less unstable airmass across the Lower Great Lakes and central Appalachians. ...Virginia/North Carolina... The Mid-Atlantic region will once again reside between upper troughing to the north over the Northeast/eastern Canada, and a mid/upper-level anticyclone anchored over the Southeast. The primary synoptic front remains draped generally east-west along/near the MD/PA/DE border. A very moist low-level airmass remains in place to the south of this boundary, with surface dewpoints generally in the low to mid 70s. A similar convective scenario to yesterday is forecast again today. Diurnal heating of this moist airmass will likely encourage moderate to locally strong MLCAPE by early afternoon, even though mid-level lapse rates are expected to remain poor. Around 15-25 kt of mid-level westerly flow should enable thunderstorms that initially develop over the Appalachians/Blue Ridge to advance eastward towards the lower elevations/coastal regions of VA/NC this afternoon and early evening. Scattered damaging winds should be the main threat with loosely organized multicells/clusters. Isolated hail may occur with the stronger cores as well. ...Northern/Central Plains... An upper trough/low is expected to persist today over western Canada. On the southern periphery of this feature, a weak mid-level shortwave trough should move eastward across the northern Rockies/High Plains through this evening. Weaker mid-level westerly flow will remain farther south into the central High Plains. At the surface, a lee trough will extend southward from eastern MT to eastern CO. Generally low to mid 60s surface dewpoints should exist this afternoon along/east of the lee trough, with greater low-level moisture present near a remnant front/boundary in NE. Isolated thunderstorms across northeast MT may pose an isolated hail threat this morning. Current expectations are for scattered thunderstorms to develop initially over the higher terrain of the northern/central Rockies this afternoon, with additional development farther east along the lee trough. As this convection spreads eastward into a moderately to strongly unstable airmass across the northern/central High Plains, it should strengthen. Weak low-level winds are forecast to veer and increase with height through mid/upper levels, supporting strong deep-layer shear and the potential for supercells. Scattered large hail will be possible with any supercells that can persist, with most guidance indicating a greater concentration of severe thunderstorms across eastern MT into western ND, and separately across western/central NE. Given the presence of steep mid-level lapse rates and 40-50+ kt of deep-layer shear, isolated very large hail appears possible. If one or more clusters can develop from the initial supercells, then a greater threat for severe gusts would be realized this evening with eastward extent across the northern/central Plains. There is low confidence in this scenario occurring, however. ..Gleason/Bentley.. 07/19/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0745 AM CDT Sat Jul 19 2025 Valid 191300Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS...MIDWEST/GREAT LAKES...AND VIRGINIA/NORTH CAROLINA... ...SUMMARY... Scattered damaging winds are possible today across parts of the Midwest/Great Lakes and southern Mid-Atlantic. Scattered large to very large hail and severe gusts are possible across the northern/central Plains during the late afternoon and evening. ...Midwest/Great Lakes... A small thunderstorm cluster ongoing this morning across southern/eastern IA should continue to track east-southeastward along an instability gradient across parts of northern MO, IL, and perhaps IN into at least the early afternoon. With sufficient organization and evidence of a cold pool, this cluster may pose a threat for strong to locally damaging winds. Reference Mesoscale Discussion 1719 for more details. The potential for additional strong to severe thunderstorms across the Midwest and Great Lakes regions remains somewhat unclear given rather nebulous/weak forcing aloft. Stronger westerly mid-level flow associated with upper troughing over eastern Canada should tend to remain mostly displaced to the north of the surface warm sector. Still, daytime heating of a moist low-level airmass will likely encourage the development of moderate to locally strong instability by early to mid afternoon away from convective influences. Somewhat stronger flow aloft and related deep-layer shear should be present this afternoon across Lower MI. A mix of multicells and marginal supercells may spread eastward from ongoing activity across WI, or develop separately over this area while posing a threat for isolated severe hail and damaging winds. Farther south into the Midwest/OH Valley, weaker deep-layer shear and the bulk of convection-allowing model guidance suggests that multicell clusters should be the main convective mode. One or more of these clusters will probably persist from the ongoing activity this morning, or develop this afternoon along its outflow. Scattered severe/damaging winds will likely be the main threat as these thunderstorms move east-southeastward this afternoon into early evening across much of the OH Valley/Midwest. This convection should eventually weaken this evening as it encounters a less unstable airmass across the Lower Great Lakes and central Appalachians. ...Virginia/North Carolina... The Mid-Atlantic region will once again reside between upper troughing to the north over the Northeast/eastern Canada, and a mid/upper-level anticyclone anchored over the Southeast. The primary synoptic front remains draped generally east-west along/near the MD/PA/DE border. A very moist low-level airmass remains in place to the south of this boundary, with surface dewpoints generally in the low to mid 70s. A similar convective scenario to yesterday is forecast again today. Diurnal heating of this moist airmass will likely encourage moderate to locally strong MLCAPE by early afternoon, even though mid-level lapse rates are expected to remain poor. Around 15-25 kt of mid-level westerly flow should enable thunderstorms that initially develop over the Appalachians/Blue Ridge to advance eastward towards the lower elevations/coastal regions of VA/NC this afternoon and early evening. Scattered damaging winds should be the main threat with loosely organized multicells/clusters. Isolated hail may occur with the stronger cores as well. ...Northern/Central Plains... An upper trough/low is expected to persist today over western Canada. On the southern periphery of this feature, a weak mid-level shortwave trough should move eastward across the northern Rockies/High Plains through this evening. Weaker mid-level westerly flow will remain farther south into the central High Plains. At the surface, a lee trough will extend southward from eastern MT to eastern CO. Generally low to mid 60s surface dewpoints should exist this afternoon along/east of the lee trough, with greater low-level moisture present near a remnant front/boundary in NE. Isolated thunderstorms across northeast MT may pose an isolated hail threat this morning. Current expectations are for scattered thunderstorms to develop initially over the higher terrain of the northern/central Rockies this afternoon, with additional development farther east along the lee trough. As this convection spreads eastward into a moderately to strongly unstable airmass across the northern/central High Plains, it should strengthen. Weak low-level winds are forecast to veer and increase with height through mid/upper levels, supporting strong deep-layer shear and the potential for supercells. Scattered large hail will be possible with any supercells that can persist, with most guidance indicating a greater concentration of severe thunderstorms across eastern MT into western ND, and separately across western/central NE. Given the presence of steep mid-level lapse rates and 40-50+ kt of deep-layer shear, isolated very large hail appears possible. If one or more clusters can develop from the initial supercells, then a greater threat for severe gusts would be realized this evening with eastward extent across the northern/central Plains. There is low confidence in this scenario occurring, however. ..Gleason/Bentley.. 07/19/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0745 AM CDT Sat Jul 19 2025 Valid 191300Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS...MIDWEST/GREAT LAKES...AND VIRGINIA/NORTH CAROLINA... ...SUMMARY... Scattered damaging winds are possible today across parts of the Midwest/Great Lakes and southern Mid-Atlantic. Scattered large to very large hail and severe gusts are possible across the northern/central Plains during the late afternoon and evening. ...Midwest/Great Lakes... A small thunderstorm cluster ongoing this morning across southern/eastern IA should continue to track east-southeastward along an instability gradient across parts of northern MO, IL, and perhaps IN into at least the early afternoon. With sufficient organization and evidence of a cold pool, this cluster may pose a threat for strong to locally damaging winds. Reference Mesoscale Discussion 1719 for more details. The potential for additional strong to severe thunderstorms across the Midwest and Great Lakes regions remains somewhat unclear given rather nebulous/weak forcing aloft. Stronger westerly mid-level flow associated with upper troughing over eastern Canada should tend to remain mostly displaced to the north of the surface warm sector. Still, daytime heating of a moist low-level airmass will likely encourage the development of moderate to locally strong instability by early to mid afternoon away from convective influences. Somewhat stronger flow aloft and related deep-layer shear should be present this afternoon across Lower MI. A mix of multicells and marginal supercells may spread eastward from ongoing activity across WI, or develop separately over this area while posing a threat for isolated severe hail and damaging winds. Farther south into the Midwest/OH Valley, weaker deep-layer shear and the bulk of convection-allowing model guidance suggests that multicell clusters should be the main convective mode. One or more of these clusters will probably persist from the ongoing activity this morning, or develop this afternoon along its outflow. Scattered severe/damaging winds will likely be the main threat as these thunderstorms move east-southeastward this afternoon into early evening across much of the OH Valley/Midwest. This convection should eventually weaken this evening as it encounters a less unstable airmass across the Lower Great Lakes and central Appalachians. ...Virginia/North Carolina... The Mid-Atlantic region will once again reside between upper troughing to the north over the Northeast/eastern Canada, and a mid/upper-level anticyclone anchored over the Southeast. The primary synoptic front remains draped generally east-west along/near the MD/PA/DE border. A very moist low-level airmass remains in place to the south of this boundary, with surface dewpoints generally in the low to mid 70s. A similar convective scenario to yesterday is forecast again today. Diurnal heating of this moist airmass will likely encourage moderate to locally strong MLCAPE by early afternoon, even though mid-level lapse rates are expected to remain poor. Around 15-25 kt of mid-level westerly flow should enable thunderstorms that initially develop over the Appalachians/Blue Ridge to advance eastward towards the lower elevations/coastal regions of VA/NC this afternoon and early evening. Scattered damaging winds should be the main threat with loosely organized multicells/clusters. Isolated hail may occur with the stronger cores as well. ...Northern/Central Plains... An upper trough/low is expected to persist today over western Canada. On the southern periphery of this feature, a weak mid-level shortwave trough should move eastward across the northern Rockies/High Plains through this evening. Weaker mid-level westerly flow will remain farther south into the central High Plains. At the surface, a lee trough will extend southward from eastern MT to eastern CO. Generally low to mid 60s surface dewpoints should exist this afternoon along/east of the lee trough, with greater low-level moisture present near a remnant front/boundary in NE. Isolated thunderstorms across northeast MT may pose an isolated hail threat this morning. Current expectations are for scattered thunderstorms to develop initially over the higher terrain of the northern/central Rockies this afternoon, with additional development farther east along the lee trough. As this convection spreads eastward into a moderately to strongly unstable airmass across the northern/central High Plains, it should strengthen. Weak low-level winds are forecast to veer and increase with height through mid/upper levels, supporting strong deep-layer shear and the potential for supercells. Scattered large hail will be possible with any supercells that can persist, with most guidance indicating a greater concentration of severe thunderstorms across eastern MT into western ND, and separately across western/central NE. Given the presence of steep mid-level lapse rates and 40-50+ kt of deep-layer shear, isolated very large hail appears possible. If one or more clusters can develop from the initial supercells, then a greater threat for severe gusts would be realized this evening with eastward extent across the northern/central Plains. There is low confidence in this scenario occurring, however. ..Gleason/Bentley.. 07/19/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0745 AM CDT Sat Jul 19 2025 Valid 191300Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS...MIDWEST/GREAT LAKES...AND VIRGINIA/NORTH CAROLINA... ...SUMMARY... Scattered damaging winds are possible today across parts of the Midwest/Great Lakes and southern Mid-Atlantic. Scattered large to very large hail and severe gusts are possible across the northern/central Plains during the late afternoon and evening. ...Midwest/Great Lakes... A small thunderstorm cluster ongoing this morning across southern/eastern IA should continue to track east-southeastward along an instability gradient across parts of northern MO, IL, and perhaps IN into at least the early afternoon. With sufficient organization and evidence of a cold pool, this cluster may pose a threat for strong to locally damaging winds. Reference Mesoscale Discussion 1719 for more details. The potential for additional strong to severe thunderstorms across the Midwest and Great Lakes regions remains somewhat unclear given rather nebulous/weak forcing aloft. Stronger westerly mid-level flow associated with upper troughing over eastern Canada should tend to remain mostly displaced to the north of the surface warm sector. Still, daytime heating of a moist low-level airmass will likely encourage the development of moderate to locally strong instability by early to mid afternoon away from convective influences. Somewhat stronger flow aloft and related deep-layer shear should be present this afternoon across Lower MI. A mix of multicells and marginal supercells may spread eastward from ongoing activity across WI, or develop separately over this area while posing a threat for isolated severe hail and damaging winds. Farther south into the Midwest/OH Valley, weaker deep-layer shear and the bulk of convection-allowing model guidance suggests that multicell clusters should be the main convective mode. One or more of these clusters will probably persist from the ongoing activity this morning, or develop this afternoon along its outflow. Scattered severe/damaging winds will likely be the main threat as these thunderstorms move east-southeastward this afternoon into early evening across much of the OH Valley/Midwest. This convection should eventually weaken this evening as it encounters a less unstable airmass across the Lower Great Lakes and central Appalachians. ...Virginia/North Carolina... The Mid-Atlantic region will once again reside between upper troughing to the north over the Northeast/eastern Canada, and a mid/upper-level anticyclone anchored over the Southeast. The primary synoptic front remains draped generally east-west along/near the MD/PA/DE border. A very moist low-level airmass remains in place to the south of this boundary, with surface dewpoints generally in the low to mid 70s. A similar convective scenario to yesterday is forecast again today. Diurnal heating of this moist airmass will likely encourage moderate to locally strong MLCAPE by early afternoon, even though mid-level lapse rates are expected to remain poor. Around 15-25 kt of mid-level westerly flow should enable thunderstorms that initially develop over the Appalachians/Blue Ridge to advance eastward towards the lower elevations/coastal regions of VA/NC this afternoon and early evening. Scattered damaging winds should be the main threat with loosely organized multicells/clusters. Isolated hail may occur with the stronger cores as well. ...Northern/Central Plains... An upper trough/low is expected to persist today over western Canada. On the southern periphery of this feature, a weak mid-level shortwave trough should move eastward across the northern Rockies/High Plains through this evening. Weaker mid-level westerly flow will remain farther south into the central High Plains. At the surface, a lee trough will extend southward from eastern MT to eastern CO. Generally low to mid 60s surface dewpoints should exist this afternoon along/east of the lee trough, with greater low-level moisture present near a remnant front/boundary in NE. Isolated thunderstorms across northeast MT may pose an isolated hail threat this morning. Current expectations are for scattered thunderstorms to develop initially over the higher terrain of the northern/central Rockies this afternoon, with additional development farther east along the lee trough. As this convection spreads eastward into a moderately to strongly unstable airmass across the northern/central High Plains, it should strengthen. Weak low-level winds are forecast to veer and increase with height through mid/upper levels, supporting strong deep-layer shear and the potential for supercells. Scattered large hail will be possible with any supercells that can persist, with most guidance indicating a greater concentration of severe thunderstorms across eastern MT into western ND, and separately across western/central NE. Given the presence of steep mid-level lapse rates and 40-50+ kt of deep-layer shear, isolated very large hail appears possible. If one or more clusters can develop from the initial supercells, then a greater threat for severe gusts would be realized this evening with eastward extent across the northern/central Plains. There is low confidence in this scenario occurring, however. ..Gleason/Bentley.. 07/19/2025 Read more

WW 0525 Status Updates
STATUS REPORT ON WW 525 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 15 WNW DSM TO 10 NE DSM TO 20 NNE OXV TO 25 NE OXV TO 30 N OTM TO 30 WSW CID TO 20 WSW CID TO 15 NW CID TO 20 NNW CID TO 35 N CID TO 45 NW DBQ. ..BENTLEY..07/19/25 ATTN...WFO...DVN...DMX... STATUS REPORT FOR WS 525 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS IAC031-055-057-087-095-101-103-105-107-113-115-117-123-125-135- 139-179-181-183-191340- IA . IOWA COUNTIES INCLUDED ARE CEDAR DELAWARE DES MOINES HENRY IOWA JEFFERSON JOHNSON JONES KEOKUK LINN LOUISA LUCAS MAHASKA MARION MONROE MUSCATINE WAPELLO WARREN WASHINGTON 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

000
ABNT20 KNHC 191230
TWOAT

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Sat Jul 19 2025

For the North Atlantic...Caribbean Sea and the Gulf of America:

Central Tropical Atlantic:
A tropical wave interacting with a broad area of low pressure is
producing disorganized showers and thunderstorms about 900 miles
west-southwest of the Cabo Verde Islands. Environmental conditions
are marginally conducive for gradual development of this system
during the next few days, as it moves westward to west-northwestward
around 10 mph. By the middle of next week, environmental
conditions are forecast to become unfavorable for further
development.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 7 days...low...20 percent.

$$
Forecaster Hagen

872
ABPZ20 KNHC 191214
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Sat Jul 19 2025

For the eastern and central North Pacific east of 180 longitude:

Well Southwest of the Baja California Peninsula:
A large area of disorganized showers and thunderstorms, associated
with a tropical wave, is located about 1300 miles southwest of the
Baja California peninsula. Environmental conditions are marginally
conducive for development of this system during the next few days
as it moves west-northwestward at 10 to 15 mph. However, by the
early to middle part of next week, conditions are expected to become
unfavorable for further development.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 7 days...low...30 percent.

$$
Forecaster Beven

WW 0525 Status Updates
STATUS REPORT ON WW 525 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 35 NW DSM TO 45 NNE OXV TO 35 ENE ALO. ..GLEASON..07/19/25 ATTN...WFO...DVN...DMX... STATUS REPORT FOR WS 525 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS IAC011-013-019-031-055-057-087-095-099-101-103-105-107-113-115- 117-123-125-135-139-153-157-171-179-181-183-191240- IA . IOWA COUNTIES INCLUDED ARE BENTON BLACK HAWK BUCHANAN CEDAR DELAWARE DES MOINES HENRY IOWA JASPER JEFFERSON JOHNSON JONES KEOKUK LINN LOUISA LUCAS MAHASKA MARION MONROE MUSCATINE POLK POWESHIEK TAMA WAPELLO WARREN WASHINGTON 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 0525 Status Updates
STATUS FOR WATCH 0525 HAS NOT BEEN ISSUED YET Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0347 AM CDT Sat Jul 19 2025 Valid 221200Z - 271200Z ...DISCUSSION... Medium-range guidance continues to indicate a belt of strengthening west-northwesterly flow across Ontario, Quebec and adjacent portions of the U.S. Upper Midwest/Great Lakes toward the St. Lawrence Valley and Northeast during the middle to latter portions of the coming work week. This is forecast to occur as a notable mid-level low, digging southeast of the Canadian Arctic latitudes over the next couple of days, accelerates east-southeast of the Canadian Northwest Territories through the Hudson Bay vicinity and northern Quebec, to the north of an increasingly prominent high becoming centered over the Ohio/Tennessee Valleys by next Wednesday/Thursday. Potential forcing for ascent associated with smaller-scale perturbations emerging from initial troughing across the Pacific Northwest, or other more subtle perturbations migrating around the northwestern periphery of the high, before progressing eastward along the southern periphery of this regime remain much more unclear. However, guidance remains suggestive that moistening beneath a plume of eastward advecting elevated mixed-layer air might become supportive of destabilization conducive to the evolution of progressive organized clusters of storms capable of producing swaths of strong to severe gusts, in the presence of favorable shear. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0347 AM CDT Sat Jul 19 2025 Valid 221200Z - 271200Z ...DISCUSSION... Medium-range guidance continues to indicate a belt of strengthening west-northwesterly flow across Ontario, Quebec and adjacent portions of the U.S. Upper Midwest/Great Lakes toward the St. Lawrence Valley and Northeast during the middle to latter portions of the coming work week. This is forecast to occur as a notable mid-level low, digging southeast of the Canadian Arctic latitudes over the next couple of days, accelerates east-southeast of the Canadian Northwest Territories through the Hudson Bay vicinity and northern Quebec, to the north of an increasingly prominent high becoming centered over the Ohio/Tennessee Valleys by next Wednesday/Thursday. Potential forcing for ascent associated with smaller-scale perturbations emerging from initial troughing across the Pacific Northwest, or other more subtle perturbations migrating around the northwestern periphery of the high, before progressing eastward along the southern periphery of this regime remain much more unclear. However, guidance remains suggestive that moistening beneath a plume of eastward advecting elevated mixed-layer air might become supportive of destabilization conducive to the evolution of progressive organized clusters of storms capable of producing swaths of strong to severe gusts, in the presence of favorable shear. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0347 AM CDT Sat Jul 19 2025 Valid 221200Z - 271200Z ...DISCUSSION... Medium-range guidance continues to indicate a belt of strengthening west-northwesterly flow across Ontario, Quebec and adjacent portions of the U.S. Upper Midwest/Great Lakes toward the St. Lawrence Valley and Northeast during the middle to latter portions of the coming work week. This is forecast to occur as a notable mid-level low, digging southeast of the Canadian Arctic latitudes over the next couple of days, accelerates east-southeast of the Canadian Northwest Territories through the Hudson Bay vicinity and northern Quebec, to the north of an increasingly prominent high becoming centered over the Ohio/Tennessee Valleys by next Wednesday/Thursday. Potential forcing for ascent associated with smaller-scale perturbations emerging from initial troughing across the Pacific Northwest, or other more subtle perturbations migrating around the northwestern periphery of the high, before progressing eastward along the southern periphery of this regime remain much more unclear. However, guidance remains suggestive that moistening beneath a plume of eastward advecting elevated mixed-layer air might become supportive of destabilization conducive to the evolution of progressive organized clusters of storms capable of producing swaths of strong to severe gusts, in the presence of favorable shear. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0347 AM CDT Sat Jul 19 2025 Valid 221200Z - 271200Z ...DISCUSSION... Medium-range guidance continues to indicate a belt of strengthening west-northwesterly flow across Ontario, Quebec and adjacent portions of the U.S. Upper Midwest/Great Lakes toward the St. Lawrence Valley and Northeast during the middle to latter portions of the coming work week. This is forecast to occur as a notable mid-level low, digging southeast of the Canadian Arctic latitudes over the next couple of days, accelerates east-southeast of the Canadian Northwest Territories through the Hudson Bay vicinity and northern Quebec, to the north of an increasingly prominent high becoming centered over the Ohio/Tennessee Valleys by next Wednesday/Thursday. Potential forcing for ascent associated with smaller-scale perturbations emerging from initial troughing across the Pacific Northwest, or other more subtle perturbations migrating around the northwestern periphery of the high, before progressing eastward along the southern periphery of this regime remain much more unclear. However, guidance remains suggestive that moistening beneath a plume of eastward advecting elevated mixed-layer air might become supportive of destabilization conducive to the evolution of progressive organized clusters of storms capable of producing swaths of strong to severe gusts, in the presence of favorable shear. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0347 AM CDT Sat Jul 19 2025 Valid 221200Z - 271200Z ...DISCUSSION... Medium-range guidance continues to indicate a belt of strengthening west-northwesterly flow across Ontario, Quebec and adjacent portions of the U.S. Upper Midwest/Great Lakes toward the St. Lawrence Valley and Northeast during the middle to latter portions of the coming work week. This is forecast to occur as a notable mid-level low, digging southeast of the Canadian Arctic latitudes over the next couple of days, accelerates east-southeast of the Canadian Northwest Territories through the Hudson Bay vicinity and northern Quebec, to the north of an increasingly prominent high becoming centered over the Ohio/Tennessee Valleys by next Wednesday/Thursday. Potential forcing for ascent associated with smaller-scale perturbations emerging from initial troughing across the Pacific Northwest, or other more subtle perturbations migrating around the northwestern periphery of the high, before progressing eastward along the southern periphery of this regime remain much more unclear. However, guidance remains suggestive that moistening beneath a plume of eastward advecting elevated mixed-layer air might become supportive of destabilization conducive to the evolution of progressive organized clusters of storms capable of producing swaths of strong to severe gusts, in the presence of favorable shear. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0347 AM CDT Sat Jul 19 2025 Valid 221200Z - 271200Z ...DISCUSSION... Medium-range guidance continues to indicate a belt of strengthening west-northwesterly flow across Ontario, Quebec and adjacent portions of the U.S. Upper Midwest/Great Lakes toward the St. Lawrence Valley and Northeast during the middle to latter portions of the coming work week. This is forecast to occur as a notable mid-level low, digging southeast of the Canadian Arctic latitudes over the next couple of days, accelerates east-southeast of the Canadian Northwest Territories through the Hudson Bay vicinity and northern Quebec, to the north of an increasingly prominent high becoming centered over the Ohio/Tennessee Valleys by next Wednesday/Thursday. Potential forcing for ascent associated with smaller-scale perturbations emerging from initial troughing across the Pacific Northwest, or other more subtle perturbations migrating around the northwestern periphery of the high, before progressing eastward along the southern periphery of this regime remain much more unclear. However, guidance remains suggestive that moistening beneath a plume of eastward advecting elevated mixed-layer air might become supportive of destabilization conducive to the evolution of progressive organized clusters of storms capable of producing swaths of strong to severe gusts, in the presence of favorable shear. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0347 AM CDT Sat Jul 19 2025 Valid 221200Z - 271200Z ...DISCUSSION... Medium-range guidance continues to indicate a belt of strengthening west-northwesterly flow across Ontario, Quebec and adjacent portions of the U.S. Upper Midwest/Great Lakes toward the St. Lawrence Valley and Northeast during the middle to latter portions of the coming work week. This is forecast to occur as a notable mid-level low, digging southeast of the Canadian Arctic latitudes over the next couple of days, accelerates east-southeast of the Canadian Northwest Territories through the Hudson Bay vicinity and northern Quebec, to the north of an increasingly prominent high becoming centered over the Ohio/Tennessee Valleys by next Wednesday/Thursday. Potential forcing for ascent associated with smaller-scale perturbations emerging from initial troughing across the Pacific Northwest, or other more subtle perturbations migrating around the northwestern periphery of the high, before progressing eastward along the southern periphery of this regime remain much more unclear. However, guidance remains suggestive that moistening beneath a plume of eastward advecting elevated mixed-layer air might become supportive of destabilization conducive to the evolution of progressive organized clusters of storms capable of producing swaths of strong to severe gusts, in the presence of favorable shear. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0347 AM CDT Sat Jul 19 2025 Valid 221200Z - 271200Z ...DISCUSSION... Medium-range guidance continues to indicate a belt of strengthening west-northwesterly flow across Ontario, Quebec and adjacent portions of the U.S. Upper Midwest/Great Lakes toward the St. Lawrence Valley and Northeast during the middle to latter portions of the coming work week. This is forecast to occur as a notable mid-level low, digging southeast of the Canadian Arctic latitudes over the next couple of days, accelerates east-southeast of the Canadian Northwest Territories through the Hudson Bay vicinity and northern Quebec, to the north of an increasingly prominent high becoming centered over the Ohio/Tennessee Valleys by next Wednesday/Thursday. Potential forcing for ascent associated with smaller-scale perturbations emerging from initial troughing across the Pacific Northwest, or other more subtle perturbations migrating around the northwestern periphery of the high, before progressing eastward along the southern periphery of this regime remain much more unclear. However, guidance remains suggestive that moistening beneath a plume of eastward advecting elevated mixed-layer air might become supportive of destabilization conducive to the evolution of progressive organized clusters of storms capable of producing swaths of strong to severe gusts, in the presence of favorable shear. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0347 AM CDT Sat Jul 19 2025 Valid 221200Z - 271200Z ...DISCUSSION... Medium-range guidance continues to indicate a belt of strengthening west-northwesterly flow across Ontario, Quebec and adjacent portions of the U.S. Upper Midwest/Great Lakes toward the St. Lawrence Valley and Northeast during the middle to latter portions of the coming work week. This is forecast to occur as a notable mid-level low, digging southeast of the Canadian Arctic latitudes over the next couple of days, accelerates east-southeast of the Canadian Northwest Territories through the Hudson Bay vicinity and northern Quebec, to the north of an increasingly prominent high becoming centered over the Ohio/Tennessee Valleys by next Wednesday/Thursday. Potential forcing for ascent associated with smaller-scale perturbations emerging from initial troughing across the Pacific Northwest, or other more subtle perturbations migrating around the northwestern periphery of the high, before progressing eastward along the southern periphery of this regime remain much more unclear. However, guidance remains suggestive that moistening beneath a plume of eastward advecting elevated mixed-layer air might become supportive of destabilization conducive to the evolution of progressive organized clusters of storms capable of producing swaths of strong to severe gusts, in the presence of favorable shear. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0347 AM CDT Sat Jul 19 2025 Valid 221200Z - 271200Z ...DISCUSSION... Medium-range guidance continues to indicate a belt of strengthening west-northwesterly flow across Ontario, Quebec and adjacent portions of the U.S. Upper Midwest/Great Lakes toward the St. Lawrence Valley and Northeast during the middle to latter portions of the coming work week. This is forecast to occur as a notable mid-level low, digging southeast of the Canadian Arctic latitudes over the next couple of days, accelerates east-southeast of the Canadian Northwest Territories through the Hudson Bay vicinity and northern Quebec, to the north of an increasingly prominent high becoming centered over the Ohio/Tennessee Valleys by next Wednesday/Thursday. Potential forcing for ascent associated with smaller-scale perturbations emerging from initial troughing across the Pacific Northwest, or other more subtle perturbations migrating around the northwestern periphery of the high, before progressing eastward along the southern periphery of this regime remain much more unclear. However, guidance remains suggestive that moistening beneath a plume of eastward advecting elevated mixed-layer air might become supportive of destabilization conducive to the evolution of progressive organized clusters of storms capable of producing swaths of strong to severe gusts, in the presence of favorable shear. Read more