Severe Storms

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0643 AM CST Sun Nov 05 2023 Valid 051300Z - 061200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATER THIS AFTERNOON INTO TONIGHT ALONG THE OR AND EXTREME NORTHWEST CA COASTS... ...SUMMARY... Isolated wind damage and a tornado or two will be possible later this afternoon into tonight along the Oregon and extreme northwest California coasts. ...Synopsis... A midlevel shortwave trough over the northern Rockies this morning will progress eastward to the upper Great Lakes by Tuesday morning. Though low-level moisture will be limited along the path of this trough, relatively steep midlevel lapse rates and sufficient midlevel moisture will support weak buoyancy rooted in the 850-700 mb layer (MUCAPE of 100-300 J/kg). Forcing for ascent in the left exit region of the mid-upper jet could support some weak elevated convection with isolated lightning flashes this evening near the SD/ND border and overnight into WI. Lingering moisture/weak buoyancy through the period could support isolated lightning flashes across ID/southern MT and vicinity, per the 12z BOI sounding. ...OR/northwest CA coasts later this afternoon into tonight... Water vapor imagery reveals a series of embedded shortwave troughs moving generally eastward toward OR later today into tonight, with multiple clusters of thunderstorms well offshore. A feed of conditionally unstable low-midlevel lapse rates and weak buoyancy (200-300 J/kg SBCAPE) will favor low-topped convection and occasional lightning flashes this afternoon into tonight as the waves progress inland, especially along the OR coast. Forecast wind profiles show sufficient hodograph length and low-level curvature for low-topped supercells with some potential to produce isolated strong gusts and possibly a tornado or two. ..Thompson.. 11/05/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0643 AM CST Sun Nov 05 2023 Valid 051300Z - 061200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATER THIS AFTERNOON INTO TONIGHT ALONG THE OR AND EXTREME NORTHWEST CA COASTS... ...SUMMARY... Isolated wind damage and a tornado or two will be possible later this afternoon into tonight along the Oregon and extreme northwest California coasts. ...Synopsis... A midlevel shortwave trough over the northern Rockies this morning will progress eastward to the upper Great Lakes by Tuesday morning. Though low-level moisture will be limited along the path of this trough, relatively steep midlevel lapse rates and sufficient midlevel moisture will support weak buoyancy rooted in the 850-700 mb layer (MUCAPE of 100-300 J/kg). Forcing for ascent in the left exit region of the mid-upper jet could support some weak elevated convection with isolated lightning flashes this evening near the SD/ND border and overnight into WI. Lingering moisture/weak buoyancy through the period could support isolated lightning flashes across ID/southern MT and vicinity, per the 12z BOI sounding. ...OR/northwest CA coasts later this afternoon into tonight... Water vapor imagery reveals a series of embedded shortwave troughs moving generally eastward toward OR later today into tonight, with multiple clusters of thunderstorms well offshore. A feed of conditionally unstable low-midlevel lapse rates and weak buoyancy (200-300 J/kg SBCAPE) will favor low-topped convection and occasional lightning flashes this afternoon into tonight as the waves progress inland, especially along the OR coast. Forecast wind profiles show sufficient hodograph length and low-level curvature for low-topped supercells with some potential to produce isolated strong gusts and possibly a tornado or two. ..Thompson.. 11/05/2023 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0221 AM CST Sun Nov 05 2023 Valid 081200Z - 131200Z ...DISCUSSION... Phased shortwave troughs are expected to result in modest upper troughing from the northern Plains/Canadian Prairies into central CA early D4/Wednesday morning. Northern-stream shortwave is forecast to make quick eastward progress while the southern-stream shortwave trough trends slower as it moves over the Southwest. At the same time, a surface low initially over KS/OK will likely move quickly northeastward across the Mid MS Valley and much of the OH Valley. Cold front attendant to this low will sweep southward/southeastward in its wake, moving through OK and the TX Panhandle and Mid MS and OH Valleys. Thunderstorms along this front will be limited by warm mid-level temperatures and resulting convective inhibition. Thunderstorm chances appear to increase on D5/Thursday across the southern Plains as the front continues gradually southward and the southern-stream shortwave trough mentioned previously continues eastward into the region. Buoyancy should remain modest, keeping severe potential low. By D6/Friday, dry and stable conditions are likely across the majority of the CONUS, with the exception of the Southeast and FL. A few thunderstorm appear possible as the front continues southeastward across the Southeast and FL on D6/Friday and D7/Saturday, but scant buoyancy will again limit the severe potential. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0221 AM CST Sun Nov 05 2023 Valid 081200Z - 131200Z ...DISCUSSION... Phased shortwave troughs are expected to result in modest upper troughing from the northern Plains/Canadian Prairies into central CA early D4/Wednesday morning. Northern-stream shortwave is forecast to make quick eastward progress while the southern-stream shortwave trough trends slower as it moves over the Southwest. At the same time, a surface low initially over KS/OK will likely move quickly northeastward across the Mid MS Valley and much of the OH Valley. Cold front attendant to this low will sweep southward/southeastward in its wake, moving through OK and the TX Panhandle and Mid MS and OH Valleys. Thunderstorms along this front will be limited by warm mid-level temperatures and resulting convective inhibition. Thunderstorm chances appear to increase on D5/Thursday across the southern Plains as the front continues gradually southward and the southern-stream shortwave trough mentioned previously continues eastward into the region. Buoyancy should remain modest, keeping severe potential low. By D6/Friday, dry and stable conditions are likely across the majority of the CONUS, with the exception of the Southeast and FL. A few thunderstorm appear possible as the front continues southeastward across the Southeast and FL on D6/Friday and D7/Saturday, but scant buoyancy will again limit the severe potential. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0221 AM CST Sun Nov 05 2023 Valid 081200Z - 131200Z ...DISCUSSION... Phased shortwave troughs are expected to result in modest upper troughing from the northern Plains/Canadian Prairies into central CA early D4/Wednesday morning. Northern-stream shortwave is forecast to make quick eastward progress while the southern-stream shortwave trough trends slower as it moves over the Southwest. At the same time, a surface low initially over KS/OK will likely move quickly northeastward across the Mid MS Valley and much of the OH Valley. Cold front attendant to this low will sweep southward/southeastward in its wake, moving through OK and the TX Panhandle and Mid MS and OH Valleys. Thunderstorms along this front will be limited by warm mid-level temperatures and resulting convective inhibition. Thunderstorm chances appear to increase on D5/Thursday across the southern Plains as the front continues gradually southward and the southern-stream shortwave trough mentioned previously continues eastward into the region. Buoyancy should remain modest, keeping severe potential low. By D6/Friday, dry and stable conditions are likely across the majority of the CONUS, with the exception of the Southeast and FL. A few thunderstorm appear possible as the front continues southeastward across the Southeast and FL on D6/Friday and D7/Saturday, but scant buoyancy will again limit the severe potential. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0221 AM CST Sun Nov 05 2023 Valid 081200Z - 131200Z ...DISCUSSION... Phased shortwave troughs are expected to result in modest upper troughing from the northern Plains/Canadian Prairies into central CA early D4/Wednesday morning. Northern-stream shortwave is forecast to make quick eastward progress while the southern-stream shortwave trough trends slower as it moves over the Southwest. At the same time, a surface low initially over KS/OK will likely move quickly northeastward across the Mid MS Valley and much of the OH Valley. Cold front attendant to this low will sweep southward/southeastward in its wake, moving through OK and the TX Panhandle and Mid MS and OH Valleys. Thunderstorms along this front will be limited by warm mid-level temperatures and resulting convective inhibition. Thunderstorm chances appear to increase on D5/Thursday across the southern Plains as the front continues gradually southward and the southern-stream shortwave trough mentioned previously continues eastward into the region. Buoyancy should remain modest, keeping severe potential low. By D6/Friday, dry and stable conditions are likely across the majority of the CONUS, with the exception of the Southeast and FL. A few thunderstorm appear possible as the front continues southeastward across the Southeast and FL on D6/Friday and D7/Saturday, but scant buoyancy will again limit the severe potential. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0157 AM CDT Sun Nov 05 2023 Valid 061200Z - 071200Z ...NO CRITICAL AREAS... ...Synopsis... As a strong mid-level jet continues to drift south through the day on Monday, some dry and breezy conditions are expected to develop across Nevada. Dry conditions are expected across much of the Southwest. However, winds remain light in this region which should alleviate most fire weather concerns. There may be some increase in initial attack across Nevada, but due to currently moist fuels, no large fires are anticipated. Elsewhere, dry conditions are expected from the Southeast into the Carolinas. However, the new large fire threat should remain minimal due to light winds. ..Bentley.. 11/05/2023 ...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 0157 AM CDT Sun Nov 05 2023 Valid 061200Z - 071200Z ...NO CRITICAL AREAS... ...Synopsis... As a strong mid-level jet continues to drift south through the day on Monday, some dry and breezy conditions are expected to develop across Nevada. Dry conditions are expected across much of the Southwest. However, winds remain light in this region which should alleviate most fire weather concerns. There may be some increase in initial attack across Nevada, but due to currently moist fuels, no large fires are anticipated. Elsewhere, dry conditions are expected from the Southeast into the Carolinas. However, the new large fire threat should remain minimal due to light winds. ..Bentley.. 11/05/2023 ...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 0157 AM CDT Sun Nov 05 2023 Valid 061200Z - 071200Z ...NO CRITICAL AREAS... ...Synopsis... As a strong mid-level jet continues to drift south through the day on Monday, some dry and breezy conditions are expected to develop across Nevada. Dry conditions are expected across much of the Southwest. However, winds remain light in this region which should alleviate most fire weather concerns. There may be some increase in initial attack across Nevada, but due to currently moist fuels, no large fires are anticipated. Elsewhere, dry conditions are expected from the Southeast into the Carolinas. However, the new large fire threat should remain minimal due to light winds. ..Bentley.. 11/05/2023 ...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 0157 AM CDT Sun Nov 05 2023 Valid 051200Z - 061200Z ...NO CRITICAL AREAS... ...Synopsis... An elongated upper-level jet will extend from the eastern Pacific into the central Rockies today. A weak mid-level shortwave is expected to cross the Rockies today which will assist in cyclogenesis across the Plains. The majority of strong winds will be where fuels remain moist and relative humidity remains high. Some dry and breezy conditions are expected across southeast Wyoming, beneath the stronger mid-level jet, but fuels in this region are moist and therefore, fire weather concerns should remain minimal. An extended dry spell across the Southeast and into the Carolinas continues to cure fuels in the region. Fuels are starting to reach critically dry levels in spots, but winds should remain light for the remainder of this weekend and into early next week. Therefore, some increase in initial attack is likely, but winds should remain too light for a greater threat. ..Bentley.. 11/05/2023 ...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 0157 AM CDT Sun Nov 05 2023 Valid 051200Z - 061200Z ...NO CRITICAL AREAS... ...Synopsis... An elongated upper-level jet will extend from the eastern Pacific into the central Rockies today. A weak mid-level shortwave is expected to cross the Rockies today which will assist in cyclogenesis across the Plains. The majority of strong winds will be where fuels remain moist and relative humidity remains high. Some dry and breezy conditions are expected across southeast Wyoming, beneath the stronger mid-level jet, but fuels in this region are moist and therefore, fire weather concerns should remain minimal. An extended dry spell across the Southeast and into the Carolinas continues to cure fuels in the region. Fuels are starting to reach critically dry levels in spots, but winds should remain light for the remainder of this weekend and into early next week. Therefore, some increase in initial attack is likely, but winds should remain too light for a greater threat. ..Bentley.. 11/05/2023 ...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 0157 AM CDT Sun Nov 05 2023 Valid 051200Z - 061200Z ...NO CRITICAL AREAS... ...Synopsis... An elongated upper-level jet will extend from the eastern Pacific into the central Rockies today. A weak mid-level shortwave is expected to cross the Rockies today which will assist in cyclogenesis across the Plains. The majority of strong winds will be where fuels remain moist and relative humidity remains high. Some dry and breezy conditions are expected across southeast Wyoming, beneath the stronger mid-level jet, but fuels in this region are moist and therefore, fire weather concerns should remain minimal. An extended dry spell across the Southeast and into the Carolinas continues to cure fuels in the region. Fuels are starting to reach critically dry levels in spots, but winds should remain light for the remainder of this weekend and into early next week. Therefore, some increase in initial attack is likely, but winds should remain too light for a greater threat. ..Bentley.. 11/05/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1247 AM CDT Sun Nov 05 2023 Valid 061200Z - 071200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms are possible from the Pacific Northwest into Idaho and far southwest Montana, as well as over Lower Michigan, on Monday. ...Synopsis and Discussion... Surface low is forecast to be over western Lake Superior early Monday morning, with a cold front extending southwestward from this low to another secondary low over central KS. The primary low is expected to progress eastward throughout the day, moving across the Upper Great Lakes and northeast Ontario into southern Quebec, just ahead of its parent shortwave trough. Portion of the front close to the low will make steady eastward progress across the Upper Great Lakes and OH Valley. Some modest buoyancy is possible across Lower MI within the warm-air advection zone ahead of the front, contributing to the potential for a few deeper updrafts and isolated lightning flashes. Southern portion of the front is expected to stall across KS and MO amid persistent low-level moisture return. Low-level convergence will be sustained along this boundary throughout much of the day, with dewpoints south of the boundary approaching 60 deg F. Even so, warm mid-level temperatures are expected to prevent deep convection and limit thunderstorm chances. Farther west, a pair of shortwave troughs are expected to impact the Pacific Northwest. The lead wave will likely move through early Monday, continuing eastward into the northern Rockies Monday evening. A second, more amplified wave will follow in the wake of the first, approaching the Pacific Northwest and northern/central CA coast early Tuesday morning. Cold mid-level temperatures amid favorable large-scale forcing for ascent will support the potential for a few deeper convective cores capable of lightning from eastern OR into southern ID during the afternoon and evening. Multiple rounds of convection are also possible along the coast as the shortwaves move through. Cold mid-level temperatures will support modest buoyancy over this region as well, with some isolated lightning possible. ..Mosier.. 11/05/2023 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1247 AM CDT Sun Nov 05 2023 Valid 061200Z - 071200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms are possible from the Pacific Northwest into Idaho and far southwest Montana, as well as over Lower Michigan, on Monday. ...Synopsis and Discussion... Surface low is forecast to be over western Lake Superior early Monday morning, with a cold front extending southwestward from this low to another secondary low over central KS. The primary low is expected to progress eastward throughout the day, moving across the Upper Great Lakes and northeast Ontario into southern Quebec, just ahead of its parent shortwave trough. Portion of the front close to the low will make steady eastward progress across the Upper Great Lakes and OH Valley. Some modest buoyancy is possible across Lower MI within the warm-air advection zone ahead of the front, contributing to the potential for a few deeper updrafts and isolated lightning flashes. Southern portion of the front is expected to stall across KS and MO amid persistent low-level moisture return. Low-level convergence will be sustained along this boundary throughout much of the day, with dewpoints south of the boundary approaching 60 deg F. Even so, warm mid-level temperatures are expected to prevent deep convection and limit thunderstorm chances. Farther west, a pair of shortwave troughs are expected to impact the Pacific Northwest. The lead wave will likely move through early Monday, continuing eastward into the northern Rockies Monday evening. A second, more amplified wave will follow in the wake of the first, approaching the Pacific Northwest and northern/central CA coast early Tuesday morning. Cold mid-level temperatures amid favorable large-scale forcing for ascent will support the potential for a few deeper convective cores capable of lightning from eastern OR into southern ID during the afternoon and evening. Multiple rounds of convection are also possible along the coast as the shortwaves move through. Cold mid-level temperatures will support modest buoyancy over this region as well, with some isolated lightning possible. ..Mosier.. 11/05/2023 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1247 AM CDT Sun Nov 05 2023 Valid 061200Z - 071200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms are possible from the Pacific Northwest into Idaho and far southwest Montana, as well as over Lower Michigan, on Monday. ...Synopsis and Discussion... Surface low is forecast to be over western Lake Superior early Monday morning, with a cold front extending southwestward from this low to another secondary low over central KS. The primary low is expected to progress eastward throughout the day, moving across the Upper Great Lakes and northeast Ontario into southern Quebec, just ahead of its parent shortwave trough. Portion of the front close to the low will make steady eastward progress across the Upper Great Lakes and OH Valley. Some modest buoyancy is possible across Lower MI within the warm-air advection zone ahead of the front, contributing to the potential for a few deeper updrafts and isolated lightning flashes. Southern portion of the front is expected to stall across KS and MO amid persistent low-level moisture return. Low-level convergence will be sustained along this boundary throughout much of the day, with dewpoints south of the boundary approaching 60 deg F. Even so, warm mid-level temperatures are expected to prevent deep convection and limit thunderstorm chances. Farther west, a pair of shortwave troughs are expected to impact the Pacific Northwest. The lead wave will likely move through early Monday, continuing eastward into the northern Rockies Monday evening. A second, more amplified wave will follow in the wake of the first, approaching the Pacific Northwest and northern/central CA coast early Tuesday morning. Cold mid-level temperatures amid favorable large-scale forcing for ascent will support the potential for a few deeper convective cores capable of lightning from eastern OR into southern ID during the afternoon and evening. Multiple rounds of convection are also possible along the coast as the shortwaves move through. Cold mid-level temperatures will support modest buoyancy over this region as well, with some isolated lightning possible. ..Mosier.. 11/05/2023 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1247 AM CDT Sun Nov 05 2023 Valid 061200Z - 071200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms are possible from the Pacific Northwest into Idaho and far southwest Montana, as well as over Lower Michigan, on Monday. ...Synopsis and Discussion... Surface low is forecast to be over western Lake Superior early Monday morning, with a cold front extending southwestward from this low to another secondary low over central KS. The primary low is expected to progress eastward throughout the day, moving across the Upper Great Lakes and northeast Ontario into southern Quebec, just ahead of its parent shortwave trough. Portion of the front close to the low will make steady eastward progress across the Upper Great Lakes and OH Valley. Some modest buoyancy is possible across Lower MI within the warm-air advection zone ahead of the front, contributing to the potential for a few deeper updrafts and isolated lightning flashes. Southern portion of the front is expected to stall across KS and MO amid persistent low-level moisture return. Low-level convergence will be sustained along this boundary throughout much of the day, with dewpoints south of the boundary approaching 60 deg F. Even so, warm mid-level temperatures are expected to prevent deep convection and limit thunderstorm chances. Farther west, a pair of shortwave troughs are expected to impact the Pacific Northwest. The lead wave will likely move through early Monday, continuing eastward into the northern Rockies Monday evening. A second, more amplified wave will follow in the wake of the first, approaching the Pacific Northwest and northern/central CA coast early Tuesday morning. Cold mid-level temperatures amid favorable large-scale forcing for ascent will support the potential for a few deeper convective cores capable of lightning from eastern OR into southern ID during the afternoon and evening. Multiple rounds of convection are also possible along the coast as the shortwaves move through. Cold mid-level temperatures will support modest buoyancy over this region as well, with some isolated lightning possible. ..Mosier.. 11/05/2023 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1241 AM CDT Sun Nov 05 2023 Valid 051200Z - 061200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Several rounds of scattered thunderstorms are expected across the Pacific Northwest this afternoon through early Monday morning. ...Synopsis... The upper-level ridge across the central CONUS will flatten through the day on Sunday. Farther west, a mid-level trough will approach the Pacific Northwest coast. At the surface, a surface low will develop across the northern Plains in response to a shortwave moving through the region. In addition, a surface low will develop off the Oregon coast and approach the Pacific Northwest coastline near the end of the period. ...Pacific Northwest Coast... Temperatures will start to cool aloft by later this afternoon off the Oregon coast. These cooling temperatures over the marine airmass will result in an increase in thunderstorm activity during the afternoon which will persist through the overnight period. Forecast soundings show marginal instability (~250 J/kg MLCAPE) and strong shear with some low-level turning. The most favorable period for rotating updrafts and potentially some enhanced low-level rotation is expected late in the period 06Z to 12Z when the surface low approaches the coast. As this occurs, cooling temperatures aloft should result in maximum instability with some backing surface winds ahead of the approaching surface low. This pattern loosely matches previous patterns which have resulted in tornadoes in the northern California/Oregon coast environment. However, at this time, forecast instability and low-level streamwise vorticity remains too limited for a marginal risk along the coast. ..Bentley.. 11/05/2023 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1241 AM CDT Sun Nov 05 2023 Valid 051200Z - 061200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Several rounds of scattered thunderstorms are expected across the Pacific Northwest this afternoon through early Monday morning. ...Synopsis... The upper-level ridge across the central CONUS will flatten through the day on Sunday. Farther west, a mid-level trough will approach the Pacific Northwest coast. At the surface, a surface low will develop across the northern Plains in response to a shortwave moving through the region. In addition, a surface low will develop off the Oregon coast and approach the Pacific Northwest coastline near the end of the period. ...Pacific Northwest Coast... Temperatures will start to cool aloft by later this afternoon off the Oregon coast. These cooling temperatures over the marine airmass will result in an increase in thunderstorm activity during the afternoon which will persist through the overnight period. Forecast soundings show marginal instability (~250 J/kg MLCAPE) and strong shear with some low-level turning. The most favorable period for rotating updrafts and potentially some enhanced low-level rotation is expected late in the period 06Z to 12Z when the surface low approaches the coast. As this occurs, cooling temperatures aloft should result in maximum instability with some backing surface winds ahead of the approaching surface low. This pattern loosely matches previous patterns which have resulted in tornadoes in the northern California/Oregon coast environment. However, at this time, forecast instability and low-level streamwise vorticity remains too limited for a marginal risk along the coast. ..Bentley.. 11/05/2023 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1241 AM CDT Sun Nov 05 2023 Valid 051200Z - 061200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Several rounds of scattered thunderstorms are expected across the Pacific Northwest this afternoon through early Monday morning. ...Synopsis... The upper-level ridge across the central CONUS will flatten through the day on Sunday. Farther west, a mid-level trough will approach the Pacific Northwest coast. At the surface, a surface low will develop across the northern Plains in response to a shortwave moving through the region. In addition, a surface low will develop off the Oregon coast and approach the Pacific Northwest coastline near the end of the period. ...Pacific Northwest Coast... Temperatures will start to cool aloft by later this afternoon off the Oregon coast. These cooling temperatures over the marine airmass will result in an increase in thunderstorm activity during the afternoon which will persist through the overnight period. Forecast soundings show marginal instability (~250 J/kg MLCAPE) and strong shear with some low-level turning. The most favorable period for rotating updrafts and potentially some enhanced low-level rotation is expected late in the period 06Z to 12Z when the surface low approaches the coast. As this occurs, cooling temperatures aloft should result in maximum instability with some backing surface winds ahead of the approaching surface low. This pattern loosely matches previous patterns which have resulted in tornadoes in the northern California/Oregon coast environment. However, at this time, forecast instability and low-level streamwise vorticity remains too limited for a marginal risk along the coast. ..Bentley.. 11/05/2023 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1241 AM CDT Sun Nov 05 2023 Valid 051200Z - 061200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Several rounds of scattered thunderstorms are expected across the Pacific Northwest this afternoon through early Monday morning. ...Synopsis... The upper-level ridge across the central CONUS will flatten through the day on Sunday. Farther west, a mid-level trough will approach the Pacific Northwest coast. At the surface, a surface low will develop across the northern Plains in response to a shortwave moving through the region. In addition, a surface low will develop off the Oregon coast and approach the Pacific Northwest coastline near the end of the period. ...Pacific Northwest Coast... Temperatures will start to cool aloft by later this afternoon off the Oregon coast. These cooling temperatures over the marine airmass will result in an increase in thunderstorm activity during the afternoon which will persist through the overnight period. Forecast soundings show marginal instability (~250 J/kg MLCAPE) and strong shear with some low-level turning. The most favorable period for rotating updrafts and potentially some enhanced low-level rotation is expected late in the period 06Z to 12Z when the surface low approaches the coast. As this occurs, cooling temperatures aloft should result in maximum instability with some backing surface winds ahead of the approaching surface low. This pattern loosely matches previous patterns which have resulted in tornadoes in the northern California/Oregon coast environment. However, at this time, forecast instability and low-level streamwise vorticity remains too limited for a marginal risk along the coast. ..Bentley.. 11/05/2023 Read more