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MD 0434 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF EXTREME NORTHERN CALIFORNIA INTO CENTRAL OREGON
Mesoscale Discussion 0434 NWS Storm Prediction Center Norman OK 0325 PM CDT Sat Apr 13 2024 Areas affected...portions of extreme northern California into central Oregon Concerning...Severe potential...Watch unlikely Valid 132025Z - 132300Z Probability of Watch Issuance...20 percent SUMMARY...Thunderstorms are expected to gradually increase in both coverage and intensity through the afternoon. Hail and strong wind gusts will be the main threats, though a brief tornado cannot be completely ruled out. The severe threat should remain isolated and a WW issuance is not expected. DISCUSSION...Despite limited surface heating, increasing deep-layer ascent, driven by the approach of a mid-level jet streak, is contributing to a gradual increase in thunderstorm coverage across parts of southern OR/northern CA. Temperatures are warming into the mid 50s F, with dewpoints near 40 F in place, supporting around 1000 J/kg SBCAPE, but under 500 J/kg of MLCAPE. Given widespread clouds in place, the boundary layer remains moist, but also cool, with the aforementioned CAPE constrained to short and narrow profiles (per 19Z RAP forecast soundings) despite steep tropospheric lapse rates in place. Shear profiles favor some severe potential, with forecast soundings showing curved and elongated hodographs, with up to 50 kts of effective bulk shear in place. As such, multicells and supercells should be the primary mode of convection, with gusty winds and hail the main threats. A brief tornado also cannot be ruled out, especially to the immediate lee of the southern Cascades, where 20Z mesoanalysis depicts a local maxima in low-level vertical vorticity coinciding with over 100 J/kg of 0-3 km CAPE. Any supercell that manages to develop and traverse this local corridor may stretch the vorticity and spawn a brief landspout/supercell hybrid tornado, though this scenario remains highly conditional. Furthermore, the overall severe threat is expected to remain isolated and a WW issuance is not anticipated. ..Squitieri/Leitman.. 04/13/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BOI...PDT...MFR...PQR... LAT...LON 41392088 41442137 41572172 41962219 42292234 43162272 43782296 44272288 44682207 44752089 44592016 44331969 44191956 43271975 42671993 42022009 41532055 41392088 Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0342 PM CDT Sat Apr 13 2024 Valid 151200Z - 211200Z A potent upper-level trough will enter the Four Corners region and eject into the southern Plains on Monday. This feature will be the primary driver of fire weather concerns in the coming days. As this trough lifts into the Midwest/Great Lakes Tuesday into Wednesday, it is forecast to weaken while another upper-level trough moves through the northern Plains and eventually the Great Lakes region by the weekend. Models have general agreement that flow aloft will become more zonal through the week. At the surface, a deep lee cyclone along the CO/KS border will develop Monday afternoon, lifting northeastward with time along with its parent upper trough. Another weaker lee cyclone may develop in the southern High Plains around midweek. As the next trough moves eastward, a cold front is expected to push into parts of the southern Plains late next week. ...Central/Southern High Plains... The deep lee cyclone and strong upper-level winds will combine to produce widespread elevated to critical fire weather across parts of New Mexico into West Texas and the central High Plains vicinity on Monday. Critical fire weather appears most likely along and east of the central/southern Rockies. While some of these areas have somewhat marginal fuel receptiveness, the potential for locally extremely critical conditions should act to compensate. RH could broadly fall to near 10% with winds of 20-35 mph (gusts of 40-50 mph). The eastern extent of the risk, particularly for parts of the Texas Panhandle/South Plain, will be determined by how much fuels have dried since the last round of precipitation a few days ago. Fire weather concerns are expected to continue into Tuesday behind the Pacific front for parts of southeastern New Mexico and West Texas. Depending on where precipitation occurs on Monday, some eastward expansion of probabilities could occur as similarly dry/windy conditions are possible into the Rolling Plains/Hill Country. For Wednesday, uncertainty remains as to the degree of fire weather risk. Given the more zonal upper-level pattern, fire weather risk should be much more spatially restricted. Models have shown increased agreement in a modest lee cyclone developing in the southern High Plains. While some elevated fire weather could occur in northeast New Mexico into southeast Colorado, critical fire weather potential is too low for highlights. ..Wendt.. 04/13/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0342 PM CDT Sat Apr 13 2024 Valid 151200Z - 211200Z A potent upper-level trough will enter the Four Corners region and eject into the southern Plains on Monday. This feature will be the primary driver of fire weather concerns in the coming days. As this trough lifts into the Midwest/Great Lakes Tuesday into Wednesday, it is forecast to weaken while another upper-level trough moves through the northern Plains and eventually the Great Lakes region by the weekend. Models have general agreement that flow aloft will become more zonal through the week. At the surface, a deep lee cyclone along the CO/KS border will develop Monday afternoon, lifting northeastward with time along with its parent upper trough. Another weaker lee cyclone may develop in the southern High Plains around midweek. As the next trough moves eastward, a cold front is expected to push into parts of the southern Plains late next week. ...Central/Southern High Plains... The deep lee cyclone and strong upper-level winds will combine to produce widespread elevated to critical fire weather across parts of New Mexico into West Texas and the central High Plains vicinity on Monday. Critical fire weather appears most likely along and east of the central/southern Rockies. While some of these areas have somewhat marginal fuel receptiveness, the potential for locally extremely critical conditions should act to compensate. RH could broadly fall to near 10% with winds of 20-35 mph (gusts of 40-50 mph). The eastern extent of the risk, particularly for parts of the Texas Panhandle/South Plain, will be determined by how much fuels have dried since the last round of precipitation a few days ago. Fire weather concerns are expected to continue into Tuesday behind the Pacific front for parts of southeastern New Mexico and West Texas. Depending on where precipitation occurs on Monday, some eastward expansion of probabilities could occur as similarly dry/windy conditions are possible into the Rolling Plains/Hill Country. For Wednesday, uncertainty remains as to the degree of fire weather risk. Given the more zonal upper-level pattern, fire weather risk should be much more spatially restricted. Models have shown increased agreement in a modest lee cyclone developing in the southern High Plains. While some elevated fire weather could occur in northeast New Mexico into southeast Colorado, critical fire weather potential is too low for highlights. ..Wendt.. 04/13/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0342 PM CDT Sat Apr 13 2024 Valid 151200Z - 211200Z A potent upper-level trough will enter the Four Corners region and eject into the southern Plains on Monday. This feature will be the primary driver of fire weather concerns in the coming days. As this trough lifts into the Midwest/Great Lakes Tuesday into Wednesday, it is forecast to weaken while another upper-level trough moves through the northern Plains and eventually the Great Lakes region by the weekend. Models have general agreement that flow aloft will become more zonal through the week. At the surface, a deep lee cyclone along the CO/KS border will develop Monday afternoon, lifting northeastward with time along with its parent upper trough. Another weaker lee cyclone may develop in the southern High Plains around midweek. As the next trough moves eastward, a cold front is expected to push into parts of the southern Plains late next week. ...Central/Southern High Plains... The deep lee cyclone and strong upper-level winds will combine to produce widespread elevated to critical fire weather across parts of New Mexico into West Texas and the central High Plains vicinity on Monday. Critical fire weather appears most likely along and east of the central/southern Rockies. While some of these areas have somewhat marginal fuel receptiveness, the potential for locally extremely critical conditions should act to compensate. RH could broadly fall to near 10% with winds of 20-35 mph (gusts of 40-50 mph). The eastern extent of the risk, particularly for parts of the Texas Panhandle/South Plain, will be determined by how much fuels have dried since the last round of precipitation a few days ago. Fire weather concerns are expected to continue into Tuesday behind the Pacific front for parts of southeastern New Mexico and West Texas. Depending on where precipitation occurs on Monday, some eastward expansion of probabilities could occur as similarly dry/windy conditions are possible into the Rolling Plains/Hill Country. For Wednesday, uncertainty remains as to the degree of fire weather risk. Given the more zonal upper-level pattern, fire weather risk should be much more spatially restricted. Models have shown increased agreement in a modest lee cyclone developing in the southern High Plains. While some elevated fire weather could occur in northeast New Mexico into southeast Colorado, critical fire weather potential is too low for highlights. ..Wendt.. 04/13/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0342 PM CDT Sat Apr 13 2024 Valid 151200Z - 211200Z A potent upper-level trough will enter the Four Corners region and eject into the southern Plains on Monday. This feature will be the primary driver of fire weather concerns in the coming days. As this trough lifts into the Midwest/Great Lakes Tuesday into Wednesday, it is forecast to weaken while another upper-level trough moves through the northern Plains and eventually the Great Lakes region by the weekend. Models have general agreement that flow aloft will become more zonal through the week. At the surface, a deep lee cyclone along the CO/KS border will develop Monday afternoon, lifting northeastward with time along with its parent upper trough. Another weaker lee cyclone may develop in the southern High Plains around midweek. As the next trough moves eastward, a cold front is expected to push into parts of the southern Plains late next week. ...Central/Southern High Plains... The deep lee cyclone and strong upper-level winds will combine to produce widespread elevated to critical fire weather across parts of New Mexico into West Texas and the central High Plains vicinity on Monday. Critical fire weather appears most likely along and east of the central/southern Rockies. While some of these areas have somewhat marginal fuel receptiveness, the potential for locally extremely critical conditions should act to compensate. RH could broadly fall to near 10% with winds of 20-35 mph (gusts of 40-50 mph). The eastern extent of the risk, particularly for parts of the Texas Panhandle/South Plain, will be determined by how much fuels have dried since the last round of precipitation a few days ago. Fire weather concerns are expected to continue into Tuesday behind the Pacific front for parts of southeastern New Mexico and West Texas. Depending on where precipitation occurs on Monday, some eastward expansion of probabilities could occur as similarly dry/windy conditions are possible into the Rolling Plains/Hill Country. For Wednesday, uncertainty remains as to the degree of fire weather risk. Given the more zonal upper-level pattern, fire weather risk should be much more spatially restricted. Models have shown increased agreement in a modest lee cyclone developing in the southern High Plains. While some elevated fire weather could occur in northeast New Mexico into southeast Colorado, critical fire weather potential is too low for highlights. ..Wendt.. 04/13/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0342 PM CDT Sat Apr 13 2024 Valid 151200Z - 211200Z A potent upper-level trough will enter the Four Corners region and eject into the southern Plains on Monday. This feature will be the primary driver of fire weather concerns in the coming days. As this trough lifts into the Midwest/Great Lakes Tuesday into Wednesday, it is forecast to weaken while another upper-level trough moves through the northern Plains and eventually the Great Lakes region by the weekend. Models have general agreement that flow aloft will become more zonal through the week. At the surface, a deep lee cyclone along the CO/KS border will develop Monday afternoon, lifting northeastward with time along with its parent upper trough. Another weaker lee cyclone may develop in the southern High Plains around midweek. As the next trough moves eastward, a cold front is expected to push into parts of the southern Plains late next week. ...Central/Southern High Plains... The deep lee cyclone and strong upper-level winds will combine to produce widespread elevated to critical fire weather across parts of New Mexico into West Texas and the central High Plains vicinity on Monday. Critical fire weather appears most likely along and east of the central/southern Rockies. While some of these areas have somewhat marginal fuel receptiveness, the potential for locally extremely critical conditions should act to compensate. RH could broadly fall to near 10% with winds of 20-35 mph (gusts of 40-50 mph). The eastern extent of the risk, particularly for parts of the Texas Panhandle/South Plain, will be determined by how much fuels have dried since the last round of precipitation a few days ago. Fire weather concerns are expected to continue into Tuesday behind the Pacific front for parts of southeastern New Mexico and West Texas. Depending on where precipitation occurs on Monday, some eastward expansion of probabilities could occur as similarly dry/windy conditions are possible into the Rolling Plains/Hill Country. For Wednesday, uncertainty remains as to the degree of fire weather risk. Given the more zonal upper-level pattern, fire weather risk should be much more spatially restricted. Models have shown increased agreement in a modest lee cyclone developing in the southern High Plains. While some elevated fire weather could occur in northeast New Mexico into southeast Colorado, critical fire weather potential is too low for highlights. ..Wendt.. 04/13/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0342 PM CDT Sat Apr 13 2024 Valid 151200Z - 211200Z A potent upper-level trough will enter the Four Corners region and eject into the southern Plains on Monday. This feature will be the primary driver of fire weather concerns in the coming days. As this trough lifts into the Midwest/Great Lakes Tuesday into Wednesday, it is forecast to weaken while another upper-level trough moves through the northern Plains and eventually the Great Lakes region by the weekend. Models have general agreement that flow aloft will become more zonal through the week. At the surface, a deep lee cyclone along the CO/KS border will develop Monday afternoon, lifting northeastward with time along with its parent upper trough. Another weaker lee cyclone may develop in the southern High Plains around midweek. As the next trough moves eastward, a cold front is expected to push into parts of the southern Plains late next week. ...Central/Southern High Plains... The deep lee cyclone and strong upper-level winds will combine to produce widespread elevated to critical fire weather across parts of New Mexico into West Texas and the central High Plains vicinity on Monday. Critical fire weather appears most likely along and east of the central/southern Rockies. While some of these areas have somewhat marginal fuel receptiveness, the potential for locally extremely critical conditions should act to compensate. RH could broadly fall to near 10% with winds of 20-35 mph (gusts of 40-50 mph). The eastern extent of the risk, particularly for parts of the Texas Panhandle/South Plain, will be determined by how much fuels have dried since the last round of precipitation a few days ago. Fire weather concerns are expected to continue into Tuesday behind the Pacific front for parts of southeastern New Mexico and West Texas. Depending on where precipitation occurs on Monday, some eastward expansion of probabilities could occur as similarly dry/windy conditions are possible into the Rolling Plains/Hill Country. For Wednesday, uncertainty remains as to the degree of fire weather risk. Given the more zonal upper-level pattern, fire weather risk should be much more spatially restricted. Models have shown increased agreement in a modest lee cyclone developing in the southern High Plains. While some elevated fire weather could occur in northeast New Mexico into southeast Colorado, critical fire weather potential is too low for highlights. ..Wendt.. 04/13/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0342 PM CDT Sat Apr 13 2024 Valid 151200Z - 211200Z A potent upper-level trough will enter the Four Corners region and eject into the southern Plains on Monday. This feature will be the primary driver of fire weather concerns in the coming days. As this trough lifts into the Midwest/Great Lakes Tuesday into Wednesday, it is forecast to weaken while another upper-level trough moves through the northern Plains and eventually the Great Lakes region by the weekend. Models have general agreement that flow aloft will become more zonal through the week. At the surface, a deep lee cyclone along the CO/KS border will develop Monday afternoon, lifting northeastward with time along with its parent upper trough. Another weaker lee cyclone may develop in the southern High Plains around midweek. As the next trough moves eastward, a cold front is expected to push into parts of the southern Plains late next week. ...Central/Southern High Plains... The deep lee cyclone and strong upper-level winds will combine to produce widespread elevated to critical fire weather across parts of New Mexico into West Texas and the central High Plains vicinity on Monday. Critical fire weather appears most likely along and east of the central/southern Rockies. While some of these areas have somewhat marginal fuel receptiveness, the potential for locally extremely critical conditions should act to compensate. RH could broadly fall to near 10% with winds of 20-35 mph (gusts of 40-50 mph). The eastern extent of the risk, particularly for parts of the Texas Panhandle/South Plain, will be determined by how much fuels have dried since the last round of precipitation a few days ago. Fire weather concerns are expected to continue into Tuesday behind the Pacific front for parts of southeastern New Mexico and West Texas. Depending on where precipitation occurs on Monday, some eastward expansion of probabilities could occur as similarly dry/windy conditions are possible into the Rolling Plains/Hill Country. For Wednesday, uncertainty remains as to the degree of fire weather risk. Given the more zonal upper-level pattern, fire weather risk should be much more spatially restricted. Models have shown increased agreement in a modest lee cyclone developing in the southern High Plains. While some elevated fire weather could occur in northeast New Mexico into southeast Colorado, critical fire weather potential is too low for highlights. ..Wendt.. 04/13/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0342 PM CDT Sat Apr 13 2024 Valid 151200Z - 211200Z A potent upper-level trough will enter the Four Corners region and eject into the southern Plains on Monday. This feature will be the primary driver of fire weather concerns in the coming days. As this trough lifts into the Midwest/Great Lakes Tuesday into Wednesday, it is forecast to weaken while another upper-level trough moves through the northern Plains and eventually the Great Lakes region by the weekend. Models have general agreement that flow aloft will become more zonal through the week. At the surface, a deep lee cyclone along the CO/KS border will develop Monday afternoon, lifting northeastward with time along with its parent upper trough. Another weaker lee cyclone may develop in the southern High Plains around midweek. As the next trough moves eastward, a cold front is expected to push into parts of the southern Plains late next week. ...Central/Southern High Plains... The deep lee cyclone and strong upper-level winds will combine to produce widespread elevated to critical fire weather across parts of New Mexico into West Texas and the central High Plains vicinity on Monday. Critical fire weather appears most likely along and east of the central/southern Rockies. While some of these areas have somewhat marginal fuel receptiveness, the potential for locally extremely critical conditions should act to compensate. RH could broadly fall to near 10% with winds of 20-35 mph (gusts of 40-50 mph). The eastern extent of the risk, particularly for parts of the Texas Panhandle/South Plain, will be determined by how much fuels have dried since the last round of precipitation a few days ago. Fire weather concerns are expected to continue into Tuesday behind the Pacific front for parts of southeastern New Mexico and West Texas. Depending on where precipitation occurs on Monday, some eastward expansion of probabilities could occur as similarly dry/windy conditions are possible into the Rolling Plains/Hill Country. For Wednesday, uncertainty remains as to the degree of fire weather risk. Given the more zonal upper-level pattern, fire weather risk should be much more spatially restricted. Models have shown increased agreement in a modest lee cyclone developing in the southern High Plains. While some elevated fire weather could occur in northeast New Mexico into southeast Colorado, critical fire weather potential is too low for highlights. ..Wendt.. 04/13/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0238 PM CDT Sat Apr 13 2024 Valid 132000Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF OREGON AND ADJACENT NORTHEASTERN CALIFORNIA... ...SUMMARY... Thunderstorms with isolated severe hail and strong wind gusts remain possible this afternoon and early evening across parts of Oregon. ...Discussion... Current forecast reasoning, and the MRGL risk area across parts of the Oregon vicinity, appear to remain valid at this time, and thus no changes are being implemented in this forecast update. The most appreciable change has been to remove the small thunder areas from the central U.S., as any lightning should remain sparse at best, and to add a small thunder area over northern Maine where sporadic lightning is ongoing, and may continue for a couple of hours. ..Goss.. 04/13/2024 .PREV DISCUSSION... /ISSUED 1106 AM CDT Sat Apr 13 2024/ ...Far Northeast California into Oregon... An upper low off the northern/central CA coast will continue to slowly migrate east through tonight. Deep-layer south/southeasterly flow on the northeast periphery of this cyclone will advect a plume of midlevel moisture and steep lapse rates over the area. Heating through broken cloud cover will allow temperatures to warm into the 60s F by mid-afternoon and MLCAPE around 500-1000 J/kg is forecast. Moderate deep shear, with 0-6km effective shear magnitudes near 35 kt will support organized clusters, or perhaps a supercell, developing in the 20-22z time frame. Isolated large hail around 1 to 1.5 inches in diameter will be possible with the strongest cells given steep lapse rates and favorable shear in the 4-6 km layer. In addition to hail, a deeply-mixed sub-cloud layer will result in inverted-v thermodynamic profiles, and isolated strong gusts may occur. While low-level moisture will remain a limiting factor for tornado potential, a brief spin-up can not be ruled out. Enlarged low-level hodographs are evident in forecast soundings and effective SRH will increase to 100-200 m2/s2 by 22-00z amid 0-3km MLCAPE near 100 J/kg. Have added a 2 percent tornado probability to reflect this low, but non-zero potential. Uncertainty in storm coverage will preclude an upgrade to Slight risk at this time. ...Great Lakes... A low-amplitude shortwave trough migrating through large-scale northwesterly flow regime will foster elevated thunderstorm development during the evening/overnight. Weak instability (MUCAPE generally less than 500 J/kg) will limit storm intensity, though steep midlevel lapse rates and cool temperatures aloft may be sufficient for a few instances of small hail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0238 PM CDT Sat Apr 13 2024 Valid 132000Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF OREGON AND ADJACENT NORTHEASTERN CALIFORNIA... ...SUMMARY... Thunderstorms with isolated severe hail and strong wind gusts remain possible this afternoon and early evening across parts of Oregon. ...Discussion... Current forecast reasoning, and the MRGL risk area across parts of the Oregon vicinity, appear to remain valid at this time, and thus no changes are being implemented in this forecast update. The most appreciable change has been to remove the small thunder areas from the central U.S., as any lightning should remain sparse at best, and to add a small thunder area over northern Maine where sporadic lightning is ongoing, and may continue for a couple of hours. ..Goss.. 04/13/2024 .PREV DISCUSSION... /ISSUED 1106 AM CDT Sat Apr 13 2024/ ...Far Northeast California into Oregon... An upper low off the northern/central CA coast will continue to slowly migrate east through tonight. Deep-layer south/southeasterly flow on the northeast periphery of this cyclone will advect a plume of midlevel moisture and steep lapse rates over the area. Heating through broken cloud cover will allow temperatures to warm into the 60s F by mid-afternoon and MLCAPE around 500-1000 J/kg is forecast. Moderate deep shear, with 0-6km effective shear magnitudes near 35 kt will support organized clusters, or perhaps a supercell, developing in the 20-22z time frame. Isolated large hail around 1 to 1.5 inches in diameter will be possible with the strongest cells given steep lapse rates and favorable shear in the 4-6 km layer. In addition to hail, a deeply-mixed sub-cloud layer will result in inverted-v thermodynamic profiles, and isolated strong gusts may occur. While low-level moisture will remain a limiting factor for tornado potential, a brief spin-up can not be ruled out. Enlarged low-level hodographs are evident in forecast soundings and effective SRH will increase to 100-200 m2/s2 by 22-00z amid 0-3km MLCAPE near 100 J/kg. Have added a 2 percent tornado probability to reflect this low, but non-zero potential. Uncertainty in storm coverage will preclude an upgrade to Slight risk at this time. ...Great Lakes... A low-amplitude shortwave trough migrating through large-scale northwesterly flow regime will foster elevated thunderstorm development during the evening/overnight. Weak instability (MUCAPE generally less than 500 J/kg) will limit storm intensity, though steep midlevel lapse rates and cool temperatures aloft may be sufficient for a few instances of small hail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0238 PM CDT Sat Apr 13 2024 Valid 132000Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF OREGON AND ADJACENT NORTHEASTERN CALIFORNIA... ...SUMMARY... Thunderstorms with isolated severe hail and strong wind gusts remain possible this afternoon and early evening across parts of Oregon. ...Discussion... Current forecast reasoning, and the MRGL risk area across parts of the Oregon vicinity, appear to remain valid at this time, and thus no changes are being implemented in this forecast update. The most appreciable change has been to remove the small thunder areas from the central U.S., as any lightning should remain sparse at best, and to add a small thunder area over northern Maine where sporadic lightning is ongoing, and may continue for a couple of hours. ..Goss.. 04/13/2024 .PREV DISCUSSION... /ISSUED 1106 AM CDT Sat Apr 13 2024/ ...Far Northeast California into Oregon... An upper low off the northern/central CA coast will continue to slowly migrate east through tonight. Deep-layer south/southeasterly flow on the northeast periphery of this cyclone will advect a plume of midlevel moisture and steep lapse rates over the area. Heating through broken cloud cover will allow temperatures to warm into the 60s F by mid-afternoon and MLCAPE around 500-1000 J/kg is forecast. Moderate deep shear, with 0-6km effective shear magnitudes near 35 kt will support organized clusters, or perhaps a supercell, developing in the 20-22z time frame. Isolated large hail around 1 to 1.5 inches in diameter will be possible with the strongest cells given steep lapse rates and favorable shear in the 4-6 km layer. In addition to hail, a deeply-mixed sub-cloud layer will result in inverted-v thermodynamic profiles, and isolated strong gusts may occur. While low-level moisture will remain a limiting factor for tornado potential, a brief spin-up can not be ruled out. Enlarged low-level hodographs are evident in forecast soundings and effective SRH will increase to 100-200 m2/s2 by 22-00z amid 0-3km MLCAPE near 100 J/kg. Have added a 2 percent tornado probability to reflect this low, but non-zero potential. Uncertainty in storm coverage will preclude an upgrade to Slight risk at this time. ...Great Lakes... A low-amplitude shortwave trough migrating through large-scale northwesterly flow regime will foster elevated thunderstorm development during the evening/overnight. Weak instability (MUCAPE generally less than 500 J/kg) will limit storm intensity, though steep midlevel lapse rates and cool temperatures aloft may be sufficient for a few instances of small hail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0238 PM CDT Sat Apr 13 2024 Valid 132000Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF OREGON AND ADJACENT NORTHEASTERN CALIFORNIA... ...SUMMARY... Thunderstorms with isolated severe hail and strong wind gusts remain possible this afternoon and early evening across parts of Oregon. ...Discussion... Current forecast reasoning, and the MRGL risk area across parts of the Oregon vicinity, appear to remain valid at this time, and thus no changes are being implemented in this forecast update. The most appreciable change has been to remove the small thunder areas from the central U.S., as any lightning should remain sparse at best, and to add a small thunder area over northern Maine where sporadic lightning is ongoing, and may continue for a couple of hours. ..Goss.. 04/13/2024 .PREV DISCUSSION... /ISSUED 1106 AM CDT Sat Apr 13 2024/ ...Far Northeast California into Oregon... An upper low off the northern/central CA coast will continue to slowly migrate east through tonight. Deep-layer south/southeasterly flow on the northeast periphery of this cyclone will advect a plume of midlevel moisture and steep lapse rates over the area. Heating through broken cloud cover will allow temperatures to warm into the 60s F by mid-afternoon and MLCAPE around 500-1000 J/kg is forecast. Moderate deep shear, with 0-6km effective shear magnitudes near 35 kt will support organized clusters, or perhaps a supercell, developing in the 20-22z time frame. Isolated large hail around 1 to 1.5 inches in diameter will be possible with the strongest cells given steep lapse rates and favorable shear in the 4-6 km layer. In addition to hail, a deeply-mixed sub-cloud layer will result in inverted-v thermodynamic profiles, and isolated strong gusts may occur. While low-level moisture will remain a limiting factor for tornado potential, a brief spin-up can not be ruled out. Enlarged low-level hodographs are evident in forecast soundings and effective SRH will increase to 100-200 m2/s2 by 22-00z amid 0-3km MLCAPE near 100 J/kg. Have added a 2 percent tornado probability to reflect this low, but non-zero potential. Uncertainty in storm coverage will preclude an upgrade to Slight risk at this time. ...Great Lakes... A low-amplitude shortwave trough migrating through large-scale northwesterly flow regime will foster elevated thunderstorm development during the evening/overnight. Weak instability (MUCAPE generally less than 500 J/kg) will limit storm intensity, though steep midlevel lapse rates and cool temperatures aloft may be sufficient for a few instances of small hail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0238 PM CDT Sat Apr 13 2024 Valid 132000Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF OREGON AND ADJACENT NORTHEASTERN CALIFORNIA... ...SUMMARY... Thunderstorms with isolated severe hail and strong wind gusts remain possible this afternoon and early evening across parts of Oregon. ...Discussion... Current forecast reasoning, and the MRGL risk area across parts of the Oregon vicinity, appear to remain valid at this time, and thus no changes are being implemented in this forecast update. The most appreciable change has been to remove the small thunder areas from the central U.S., as any lightning should remain sparse at best, and to add a small thunder area over northern Maine where sporadic lightning is ongoing, and may continue for a couple of hours. ..Goss.. 04/13/2024 .PREV DISCUSSION... /ISSUED 1106 AM CDT Sat Apr 13 2024/ ...Far Northeast California into Oregon... An upper low off the northern/central CA coast will continue to slowly migrate east through tonight. Deep-layer south/southeasterly flow on the northeast periphery of this cyclone will advect a plume of midlevel moisture and steep lapse rates over the area. Heating through broken cloud cover will allow temperatures to warm into the 60s F by mid-afternoon and MLCAPE around 500-1000 J/kg is forecast. Moderate deep shear, with 0-6km effective shear magnitudes near 35 kt will support organized clusters, or perhaps a supercell, developing in the 20-22z time frame. Isolated large hail around 1 to 1.5 inches in diameter will be possible with the strongest cells given steep lapse rates and favorable shear in the 4-6 km layer. In addition to hail, a deeply-mixed sub-cloud layer will result in inverted-v thermodynamic profiles, and isolated strong gusts may occur. While low-level moisture will remain a limiting factor for tornado potential, a brief spin-up can not be ruled out. Enlarged low-level hodographs are evident in forecast soundings and effective SRH will increase to 100-200 m2/s2 by 22-00z amid 0-3km MLCAPE near 100 J/kg. Have added a 2 percent tornado probability to reflect this low, but non-zero potential. Uncertainty in storm coverage will preclude an upgrade to Slight risk at this time. ...Great Lakes... A low-amplitude shortwave trough migrating through large-scale northwesterly flow regime will foster elevated thunderstorm development during the evening/overnight. Weak instability (MUCAPE generally less than 500 J/kg) will limit storm intensity, though steep midlevel lapse rates and cool temperatures aloft may be sufficient for a few instances of small hail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0238 PM CDT Sat Apr 13 2024 Valid 132000Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF OREGON AND ADJACENT NORTHEASTERN CALIFORNIA... ...SUMMARY... Thunderstorms with isolated severe hail and strong wind gusts remain possible this afternoon and early evening across parts of Oregon. ...Discussion... Current forecast reasoning, and the MRGL risk area across parts of the Oregon vicinity, appear to remain valid at this time, and thus no changes are being implemented in this forecast update. The most appreciable change has been to remove the small thunder areas from the central U.S., as any lightning should remain sparse at best, and to add a small thunder area over northern Maine where sporadic lightning is ongoing, and may continue for a couple of hours. ..Goss.. 04/13/2024 .PREV DISCUSSION... /ISSUED 1106 AM CDT Sat Apr 13 2024/ ...Far Northeast California into Oregon... An upper low off the northern/central CA coast will continue to slowly migrate east through tonight. Deep-layer south/southeasterly flow on the northeast periphery of this cyclone will advect a plume of midlevel moisture and steep lapse rates over the area. Heating through broken cloud cover will allow temperatures to warm into the 60s F by mid-afternoon and MLCAPE around 500-1000 J/kg is forecast. Moderate deep shear, with 0-6km effective shear magnitudes near 35 kt will support organized clusters, or perhaps a supercell, developing in the 20-22z time frame. Isolated large hail around 1 to 1.5 inches in diameter will be possible with the strongest cells given steep lapse rates and favorable shear in the 4-6 km layer. In addition to hail, a deeply-mixed sub-cloud layer will result in inverted-v thermodynamic profiles, and isolated strong gusts may occur. While low-level moisture will remain a limiting factor for tornado potential, a brief spin-up can not be ruled out. Enlarged low-level hodographs are evident in forecast soundings and effective SRH will increase to 100-200 m2/s2 by 22-00z amid 0-3km MLCAPE near 100 J/kg. Have added a 2 percent tornado probability to reflect this low, but non-zero potential. Uncertainty in storm coverage will preclude an upgrade to Slight risk at this time. ...Great Lakes... A low-amplitude shortwave trough migrating through large-scale northwesterly flow regime will foster elevated thunderstorm development during the evening/overnight. Weak instability (MUCAPE generally less than 500 J/kg) will limit storm intensity, though steep midlevel lapse rates and cool temperatures aloft may be sufficient for a few instances of small hail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0238 PM CDT Sat Apr 13 2024 Valid 132000Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF OREGON AND ADJACENT NORTHEASTERN CALIFORNIA... ...SUMMARY... Thunderstorms with isolated severe hail and strong wind gusts remain possible this afternoon and early evening across parts of Oregon. ...Discussion... Current forecast reasoning, and the MRGL risk area across parts of the Oregon vicinity, appear to remain valid at this time, and thus no changes are being implemented in this forecast update. The most appreciable change has been to remove the small thunder areas from the central U.S., as any lightning should remain sparse at best, and to add a small thunder area over northern Maine where sporadic lightning is ongoing, and may continue for a couple of hours. ..Goss.. 04/13/2024 .PREV DISCUSSION... /ISSUED 1106 AM CDT Sat Apr 13 2024/ ...Far Northeast California into Oregon... An upper low off the northern/central CA coast will continue to slowly migrate east through tonight. Deep-layer south/southeasterly flow on the northeast periphery of this cyclone will advect a plume of midlevel moisture and steep lapse rates over the area. Heating through broken cloud cover will allow temperatures to warm into the 60s F by mid-afternoon and MLCAPE around 500-1000 J/kg is forecast. Moderate deep shear, with 0-6km effective shear magnitudes near 35 kt will support organized clusters, or perhaps a supercell, developing in the 20-22z time frame. Isolated large hail around 1 to 1.5 inches in diameter will be possible with the strongest cells given steep lapse rates and favorable shear in the 4-6 km layer. In addition to hail, a deeply-mixed sub-cloud layer will result in inverted-v thermodynamic profiles, and isolated strong gusts may occur. While low-level moisture will remain a limiting factor for tornado potential, a brief spin-up can not be ruled out. Enlarged low-level hodographs are evident in forecast soundings and effective SRH will increase to 100-200 m2/s2 by 22-00z amid 0-3km MLCAPE near 100 J/kg. Have added a 2 percent tornado probability to reflect this low, but non-zero potential. Uncertainty in storm coverage will preclude an upgrade to Slight risk at this time. ...Great Lakes... A low-amplitude shortwave trough migrating through large-scale northwesterly flow regime will foster elevated thunderstorm development during the evening/overnight. Weak instability (MUCAPE generally less than 500 J/kg) will limit storm intensity, though steep midlevel lapse rates and cool temperatures aloft may be sufficient for a few instances of small hail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0238 PM CDT Sat Apr 13 2024 Valid 132000Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF OREGON AND ADJACENT NORTHEASTERN CALIFORNIA... ...SUMMARY... Thunderstorms with isolated severe hail and strong wind gusts remain possible this afternoon and early evening across parts of Oregon. ...Discussion... Current forecast reasoning, and the MRGL risk area across parts of the Oregon vicinity, appear to remain valid at this time, and thus no changes are being implemented in this forecast update. The most appreciable change has been to remove the small thunder areas from the central U.S., as any lightning should remain sparse at best, and to add a small thunder area over northern Maine where sporadic lightning is ongoing, and may continue for a couple of hours. ..Goss.. 04/13/2024 .PREV DISCUSSION... /ISSUED 1106 AM CDT Sat Apr 13 2024/ ...Far Northeast California into Oregon... An upper low off the northern/central CA coast will continue to slowly migrate east through tonight. Deep-layer south/southeasterly flow on the northeast periphery of this cyclone will advect a plume of midlevel moisture and steep lapse rates over the area. Heating through broken cloud cover will allow temperatures to warm into the 60s F by mid-afternoon and MLCAPE around 500-1000 J/kg is forecast. Moderate deep shear, with 0-6km effective shear magnitudes near 35 kt will support organized clusters, or perhaps a supercell, developing in the 20-22z time frame. Isolated large hail around 1 to 1.5 inches in diameter will be possible with the strongest cells given steep lapse rates and favorable shear in the 4-6 km layer. In addition to hail, a deeply-mixed sub-cloud layer will result in inverted-v thermodynamic profiles, and isolated strong gusts may occur. While low-level moisture will remain a limiting factor for tornado potential, a brief spin-up can not be ruled out. Enlarged low-level hodographs are evident in forecast soundings and effective SRH will increase to 100-200 m2/s2 by 22-00z amid 0-3km MLCAPE near 100 J/kg. Have added a 2 percent tornado probability to reflect this low, but non-zero potential. Uncertainty in storm coverage will preclude an upgrade to Slight risk at this time. ...Great Lakes... A low-amplitude shortwave trough migrating through large-scale northwesterly flow regime will foster elevated thunderstorm development during the evening/overnight. Weak instability (MUCAPE generally less than 500 J/kg) will limit storm intensity, though steep midlevel lapse rates and cool temperatures aloft may be sufficient for a few instances of small hail. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0131 PM CDT Sat Apr 13 2024 Valid 141200Z - 151200Z No changes to the ongoing forecast. ..Wendt.. 04/13/2024 .PREV DISCUSSION... /ISSUED 0146 AM CDT Sat Apr 13 2024/ ...Synopsis... Fire weather conditions are expected again on Sunday across a broad swath of the Four Corners region with more concentrated areas of elevated conditions across the southern High Plains. The upper low currently off the central CA coast is forecast to move onshore over the next 48 hours, reaching the lower CO River Valley region by late Sunday. This will result in surface pressure falls across much of the intermountain West with an accompanying uptick in low-level winds. Widespread fire weather conditions are anticipated across much of the Four Corners region, but fuel analyses suggest that most fuels are currently not receptive. A weaker low-level mass response is anticipated further east across the southern High Plains, but corridors of dry/windy conditions are anticipated over areas with receptive fuels. ...Southeast NM to the southern Permian Basin... Both deterministic and ensemble guidance show the potential for pockets of elevated fire weather conditions across NM into adjacent areas of western TX and southern CO. However, the most consistent signal among all solutions appears to be across southeast NM into the southern Permian Basin where 15-20 mph winds and RH in the single digits to low teens are expected. This signal is likely attributable to topographical influences with enhanced downslope warming/drying in the lee of the Guadelupe Mountains within a modest west/southwesterly flow regime. Dry grasses across this region should support the fire weather concern, and fuel guidance will be monitored across the Four Corners region given the relatively higher confidence for elevated (to locally critical) fire weather conditions. ...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 0131 PM CDT Sat Apr 13 2024 Valid 141200Z - 151200Z No changes to the ongoing forecast. ..Wendt.. 04/13/2024 .PREV DISCUSSION... /ISSUED 0146 AM CDT Sat Apr 13 2024/ ...Synopsis... Fire weather conditions are expected again on Sunday across a broad swath of the Four Corners region with more concentrated areas of elevated conditions across the southern High Plains. The upper low currently off the central CA coast is forecast to move onshore over the next 48 hours, reaching the lower CO River Valley region by late Sunday. This will result in surface pressure falls across much of the intermountain West with an accompanying uptick in low-level winds. Widespread fire weather conditions are anticipated across much of the Four Corners region, but fuel analyses suggest that most fuels are currently not receptive. A weaker low-level mass response is anticipated further east across the southern High Plains, but corridors of dry/windy conditions are anticipated over areas with receptive fuels. ...Southeast NM to the southern Permian Basin... Both deterministic and ensemble guidance show the potential for pockets of elevated fire weather conditions across NM into adjacent areas of western TX and southern CO. However, the most consistent signal among all solutions appears to be across southeast NM into the southern Permian Basin where 15-20 mph winds and RH in the single digits to low teens are expected. This signal is likely attributable to topographical influences with enhanced downslope warming/drying in the lee of the Guadelupe Mountains within a modest west/southwesterly flow regime. Dry grasses across this region should support the fire weather concern, and fuel guidance will be monitored across the Four Corners region given the relatively higher confidence for elevated (to locally critical) fire weather conditions. ...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 0131 PM CDT Sat Apr 13 2024 Valid 141200Z - 151200Z No changes to the ongoing forecast. ..Wendt.. 04/13/2024 .PREV DISCUSSION... /ISSUED 0146 AM CDT Sat Apr 13 2024/ ...Synopsis... Fire weather conditions are expected again on Sunday across a broad swath of the Four Corners region with more concentrated areas of elevated conditions across the southern High Plains. The upper low currently off the central CA coast is forecast to move onshore over the next 48 hours, reaching the lower CO River Valley region by late Sunday. This will result in surface pressure falls across much of the intermountain West with an accompanying uptick in low-level winds. Widespread fire weather conditions are anticipated across much of the Four Corners region, but fuel analyses suggest that most fuels are currently not receptive. A weaker low-level mass response is anticipated further east across the southern High Plains, but corridors of dry/windy conditions are anticipated over areas with receptive fuels. ...Southeast NM to the southern Permian Basin... Both deterministic and ensemble guidance show the potential for pockets of elevated fire weather conditions across NM into adjacent areas of western TX and southern CO. However, the most consistent signal among all solutions appears to be across southeast NM into the southern Permian Basin where 15-20 mph winds and RH in the single digits to low teens are expected. This signal is likely attributable to topographical influences with enhanced downslope warming/drying in the lee of the Guadelupe Mountains within a modest west/southwesterly flow regime. Dry grasses across this region should support the fire weather concern, and fuel guidance will be monitored across the Four Corners region given the relatively higher confidence for elevated (to locally critical) fire weather conditions. ...Please see www.spc.noaa.gov/fire for graphic product... Read more