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SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1200 AM CST Fri Dec 29 2023 Valid 301200Z - 311200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms may occur Saturday across portions of California. Severe thunderstorms are not expected. ...Synopsis and Discussion... Isolated thunderstorms may be ongoing at the start of the period Saturday morning along/near parts of the CA Coast in association with an upper trough. Cold mid-level temperatures and modest daytime heating should support enough weak instability for occasional lighting flashes with low-topped convection through the morning as the upper trough moves eastward across CA and towards the Great Basin. Moisture and instability should eventually become too meager to foster a meaningful threat of lightning with eastward extent over the Sierras. Elsewhere across the CONUS, dry and/or stable conditions will likely preclude thunderstorms. ..Gleason.. 12/29/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1200 AM CST Fri Dec 29 2023 Valid 301200Z - 311200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms may occur Saturday across portions of California. Severe thunderstorms are not expected. ...Synopsis and Discussion... Isolated thunderstorms may be ongoing at the start of the period Saturday morning along/near parts of the CA Coast in association with an upper trough. Cold mid-level temperatures and modest daytime heating should support enough weak instability for occasional lighting flashes with low-topped convection through the morning as the upper trough moves eastward across CA and towards the Great Basin. Moisture and instability should eventually become too meager to foster a meaningful threat of lightning with eastward extent over the Sierras. Elsewhere across the CONUS, dry and/or stable conditions will likely preclude thunderstorms. ..Gleason.. 12/29/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1200 AM CST Fri Dec 29 2023 Valid 301200Z - 311200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms may occur Saturday across portions of California. Severe thunderstorms are not expected. ...Synopsis and Discussion... Isolated thunderstorms may be ongoing at the start of the period Saturday morning along/near parts of the CA Coast in association with an upper trough. Cold mid-level temperatures and modest daytime heating should support enough weak instability for occasional lighting flashes with low-topped convection through the morning as the upper trough moves eastward across CA and towards the Great Basin. Moisture and instability should eventually become too meager to foster a meaningful threat of lightning with eastward extent over the Sierras. Elsewhere across the CONUS, dry and/or stable conditions will likely preclude thunderstorms. ..Gleason.. 12/29/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1200 AM CST Fri Dec 29 2023 Valid 301200Z - 311200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms may occur Saturday across portions of California. Severe thunderstorms are not expected. ...Synopsis and Discussion... Isolated thunderstorms may be ongoing at the start of the period Saturday morning along/near parts of the CA Coast in association with an upper trough. Cold mid-level temperatures and modest daytime heating should support enough weak instability for occasional lighting flashes with low-topped convection through the morning as the upper trough moves eastward across CA and towards the Great Basin. Moisture and instability should eventually become too meager to foster a meaningful threat of lightning with eastward extent over the Sierras. Elsewhere across the CONUS, dry and/or stable conditions will likely preclude thunderstorms. ..Gleason.. 12/29/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1200 AM CST Fri Dec 29 2023 Valid 301200Z - 311200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms may occur Saturday across portions of California. Severe thunderstorms are not expected. ...Synopsis and Discussion... Isolated thunderstorms may be ongoing at the start of the period Saturday morning along/near parts of the CA Coast in association with an upper trough. Cold mid-level temperatures and modest daytime heating should support enough weak instability for occasional lighting flashes with low-topped convection through the morning as the upper trough moves eastward across CA and towards the Great Basin. Moisture and instability should eventually become too meager to foster a meaningful threat of lightning with eastward extent over the Sierras. Elsewhere across the CONUS, dry and/or stable conditions will likely preclude thunderstorms. ..Gleason.. 12/29/2023 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1116 PM CST Thu Dec 28 2023 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for thunderstorms appears negligible across much of the nation today, but showers and isolated thunderstorms are possible near southern Oregon through northern and central California coastal areas this evening through early Saturday. ...Discussion... A significant short wave trough, which has emerged from a strong, zonal mid/upper jet extending across the southern mid-latitude western through central Pacific, maintains considerable strength as it slowly progresses across the eastern Pacific. However, models indicate considerable deformation and weakening of this feature as it continues eastward into an amplified split flow, which includes building large-scale mid/upper ridging across and inland of the Pacific coast. While an initially broad and deep, associated occluding cyclone is forecast to weaken while migrating north-northeastward into areas offshore of the British Columbia coast, models indicate that the trailing front will advance inland across the Pacific coast. Based on forecast soundings and other model output, relatively warm layers in mid/upper levels probably will minimize the risk for convection capable of producing lightning along and ahead of the surface front. However, in the post-frontal regime, the leading edge of the stronger mid-level cooling (including 500 mb temperatures approaching and falling below -24 C) may begin contributing to thermodynamic profiles more conducive to weak low-topped thunderstorm activity by this evening, near southern Oregon/northern California coastal areas. A similar environment may gradually develop southward near central California coastal through 12Z Saturday. ..Kerr.. 12/29/2023 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1116 PM CST Thu Dec 28 2023 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for thunderstorms appears negligible across much of the nation today, but showers and isolated thunderstorms are possible near southern Oregon through northern and central California coastal areas this evening through early Saturday. ...Discussion... A significant short wave trough, which has emerged from a strong, zonal mid/upper jet extending across the southern mid-latitude western through central Pacific, maintains considerable strength as it slowly progresses across the eastern Pacific. However, models indicate considerable deformation and weakening of this feature as it continues eastward into an amplified split flow, which includes building large-scale mid/upper ridging across and inland of the Pacific coast. While an initially broad and deep, associated occluding cyclone is forecast to weaken while migrating north-northeastward into areas offshore of the British Columbia coast, models indicate that the trailing front will advance inland across the Pacific coast. Based on forecast soundings and other model output, relatively warm layers in mid/upper levels probably will minimize the risk for convection capable of producing lightning along and ahead of the surface front. However, in the post-frontal regime, the leading edge of the stronger mid-level cooling (including 500 mb temperatures approaching and falling below -24 C) may begin contributing to thermodynamic profiles more conducive to weak low-topped thunderstorm activity by this evening, near southern Oregon/northern California coastal areas. A similar environment may gradually develop southward near central California coastal through 12Z Saturday. ..Kerr.. 12/29/2023 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1116 PM CST Thu Dec 28 2023 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for thunderstorms appears negligible across much of the nation today, but showers and isolated thunderstorms are possible near southern Oregon through northern and central California coastal areas this evening through early Saturday. ...Discussion... A significant short wave trough, which has emerged from a strong, zonal mid/upper jet extending across the southern mid-latitude western through central Pacific, maintains considerable strength as it slowly progresses across the eastern Pacific. However, models indicate considerable deformation and weakening of this feature as it continues eastward into an amplified split flow, which includes building large-scale mid/upper ridging across and inland of the Pacific coast. While an initially broad and deep, associated occluding cyclone is forecast to weaken while migrating north-northeastward into areas offshore of the British Columbia coast, models indicate that the trailing front will advance inland across the Pacific coast. Based on forecast soundings and other model output, relatively warm layers in mid/upper levels probably will minimize the risk for convection capable of producing lightning along and ahead of the surface front. However, in the post-frontal regime, the leading edge of the stronger mid-level cooling (including 500 mb temperatures approaching and falling below -24 C) may begin contributing to thermodynamic profiles more conducive to weak low-topped thunderstorm activity by this evening, near southern Oregon/northern California coastal areas. A similar environment may gradually develop southward near central California coastal through 12Z Saturday. ..Kerr.. 12/29/2023 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1116 PM CST Thu Dec 28 2023 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for thunderstorms appears negligible across much of the nation today, but showers and isolated thunderstorms are possible near southern Oregon through northern and central California coastal areas this evening through early Saturday. ...Discussion... A significant short wave trough, which has emerged from a strong, zonal mid/upper jet extending across the southern mid-latitude western through central Pacific, maintains considerable strength as it slowly progresses across the eastern Pacific. However, models indicate considerable deformation and weakening of this feature as it continues eastward into an amplified split flow, which includes building large-scale mid/upper ridging across and inland of the Pacific coast. While an initially broad and deep, associated occluding cyclone is forecast to weaken while migrating north-northeastward into areas offshore of the British Columbia coast, models indicate that the trailing front will advance inland across the Pacific coast. Based on forecast soundings and other model output, relatively warm layers in mid/upper levels probably will minimize the risk for convection capable of producing lightning along and ahead of the surface front. However, in the post-frontal regime, the leading edge of the stronger mid-level cooling (including 500 mb temperatures approaching and falling below -24 C) may begin contributing to thermodynamic profiles more conducive to weak low-topped thunderstorm activity by this evening, near southern Oregon/northern California coastal areas. A similar environment may gradually develop southward near central California coastal through 12Z Saturday. ..Kerr.. 12/29/2023 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1116 PM CST Thu Dec 28 2023 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for thunderstorms appears negligible across much of the nation today, but showers and isolated thunderstorms are possible near southern Oregon through northern and central California coastal areas this evening through early Saturday. ...Discussion... A significant short wave trough, which has emerged from a strong, zonal mid/upper jet extending across the southern mid-latitude western through central Pacific, maintains considerable strength as it slowly progresses across the eastern Pacific. However, models indicate considerable deformation and weakening of this feature as it continues eastward into an amplified split flow, which includes building large-scale mid/upper ridging across and inland of the Pacific coast. While an initially broad and deep, associated occluding cyclone is forecast to weaken while migrating north-northeastward into areas offshore of the British Columbia coast, models indicate that the trailing front will advance inland across the Pacific coast. Based on forecast soundings and other model output, relatively warm layers in mid/upper levels probably will minimize the risk for convection capable of producing lightning along and ahead of the surface front. However, in the post-frontal regime, the leading edge of the stronger mid-level cooling (including 500 mb temperatures approaching and falling below -24 C) may begin contributing to thermodynamic profiles more conducive to weak low-topped thunderstorm activity by this evening, near southern Oregon/northern California coastal areas. A similar environment may gradually develop southward near central California coastal through 12Z Saturday. ..Kerr.. 12/29/2023 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1116 PM CST Thu Dec 28 2023 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for thunderstorms appears negligible across much of the nation today, but showers and isolated thunderstorms are possible near southern Oregon through northern and central California coastal areas this evening through early Saturday. ...Discussion... A significant short wave trough, which has emerged from a strong, zonal mid/upper jet extending across the southern mid-latitude western through central Pacific, maintains considerable strength as it slowly progresses across the eastern Pacific. However, models indicate considerable deformation and weakening of this feature as it continues eastward into an amplified split flow, which includes building large-scale mid/upper ridging across and inland of the Pacific coast. While an initially broad and deep, associated occluding cyclone is forecast to weaken while migrating north-northeastward into areas offshore of the British Columbia coast, models indicate that the trailing front will advance inland across the Pacific coast. Based on forecast soundings and other model output, relatively warm layers in mid/upper levels probably will minimize the risk for convection capable of producing lightning along and ahead of the surface front. However, in the post-frontal regime, the leading edge of the stronger mid-level cooling (including 500 mb temperatures approaching and falling below -24 C) may begin contributing to thermodynamic profiles more conducive to weak low-topped thunderstorm activity by this evening, near southern Oregon/northern California coastal areas. A similar environment may gradually develop southward near central California coastal through 12Z Saturday. ..Kerr.. 12/29/2023 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1116 PM CST Thu Dec 28 2023 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for thunderstorms appears negligible across much of the nation today, but showers and isolated thunderstorms are possible near southern Oregon through northern and central California coastal areas this evening through early Saturday. ...Discussion... A significant short wave trough, which has emerged from a strong, zonal mid/upper jet extending across the southern mid-latitude western through central Pacific, maintains considerable strength as it slowly progresses across the eastern Pacific. However, models indicate considerable deformation and weakening of this feature as it continues eastward into an amplified split flow, which includes building large-scale mid/upper ridging across and inland of the Pacific coast. While an initially broad and deep, associated occluding cyclone is forecast to weaken while migrating north-northeastward into areas offshore of the British Columbia coast, models indicate that the trailing front will advance inland across the Pacific coast. Based on forecast soundings and other model output, relatively warm layers in mid/upper levels probably will minimize the risk for convection capable of producing lightning along and ahead of the surface front. However, in the post-frontal regime, the leading edge of the stronger mid-level cooling (including 500 mb temperatures approaching and falling below -24 C) may begin contributing to thermodynamic profiles more conducive to weak low-topped thunderstorm activity by this evening, near southern Oregon/northern California coastal areas. A similar environment may gradually develop southward near central California coastal through 12Z Saturday. ..Kerr.. 12/29/2023 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0634 PM CST Thu Dec 28 2023 Valid 290100Z - 291200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of thunderstorms appears negligible across the U.S. through tonight. ...01Z Update... A large, vigorous short wave trough has emerged from a strong, zonal mid/upper jet extending across the southern mid-latitude western through central Pacific. However, models suggest that this feature, and an associated surface cyclone, will slowly begin to weaken while gradually progressing across the eastern mid-latitude Pacific, toward the Pacific coast, through 12Z Friday. With the leading edge of the stronger mid-level cooling forecast to remain well offshore through the remainder of this period (and generally not forecast to reach Oregon/California coastal areas until tomorrow evening), appreciable boundary-layer destabilization appears unlikely. Models do suggest that lower/mid-tropospheric warm advection and moistening may contribute to an inland spreading band of weak elevated destabilization across northern California and southern Oregon coastal areas around or after 29/08-10Z. However, a combination of weak mid/upper forcing for upward vertical motion and relatively warm layers aloft appear to preclude an appreciable risk for convection capable of producing lightning. ..Kerr.. 12/29/2023 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0634 PM CST Thu Dec 28 2023 Valid 290100Z - 291200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of thunderstorms appears negligible across the U.S. through tonight. ...01Z Update... A large, vigorous short wave trough has emerged from a strong, zonal mid/upper jet extending across the southern mid-latitude western through central Pacific. However, models suggest that this feature, and an associated surface cyclone, will slowly begin to weaken while gradually progressing across the eastern mid-latitude Pacific, toward the Pacific coast, through 12Z Friday. With the leading edge of the stronger mid-level cooling forecast to remain well offshore through the remainder of this period (and generally not forecast to reach Oregon/California coastal areas until tomorrow evening), appreciable boundary-layer destabilization appears unlikely. Models do suggest that lower/mid-tropospheric warm advection and moistening may contribute to an inland spreading band of weak elevated destabilization across northern California and southern Oregon coastal areas around or after 29/08-10Z. However, a combination of weak mid/upper forcing for upward vertical motion and relatively warm layers aloft appear to preclude an appreciable risk for convection capable of producing lightning. ..Kerr.. 12/29/2023 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0634 PM CST Thu Dec 28 2023 Valid 290100Z - 291200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of thunderstorms appears negligible across the U.S. through tonight. ...01Z Update... A large, vigorous short wave trough has emerged from a strong, zonal mid/upper jet extending across the southern mid-latitude western through central Pacific. However, models suggest that this feature, and an associated surface cyclone, will slowly begin to weaken while gradually progressing across the eastern mid-latitude Pacific, toward the Pacific coast, through 12Z Friday. With the leading edge of the stronger mid-level cooling forecast to remain well offshore through the remainder of this period (and generally not forecast to reach Oregon/California coastal areas until tomorrow evening), appreciable boundary-layer destabilization appears unlikely. Models do suggest that lower/mid-tropospheric warm advection and moistening may contribute to an inland spreading band of weak elevated destabilization across northern California and southern Oregon coastal areas around or after 29/08-10Z. However, a combination of weak mid/upper forcing for upward vertical motion and relatively warm layers aloft appear to preclude an appreciable risk for convection capable of producing lightning. ..Kerr.. 12/29/2023 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0634 PM CST Thu Dec 28 2023 Valid 290100Z - 291200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of thunderstorms appears negligible across the U.S. through tonight. ...01Z Update... A large, vigorous short wave trough has emerged from a strong, zonal mid/upper jet extending across the southern mid-latitude western through central Pacific. However, models suggest that this feature, and an associated surface cyclone, will slowly begin to weaken while gradually progressing across the eastern mid-latitude Pacific, toward the Pacific coast, through 12Z Friday. With the leading edge of the stronger mid-level cooling forecast to remain well offshore through the remainder of this period (and generally not forecast to reach Oregon/California coastal areas until tomorrow evening), appreciable boundary-layer destabilization appears unlikely. Models do suggest that lower/mid-tropospheric warm advection and moistening may contribute to an inland spreading band of weak elevated destabilization across northern California and southern Oregon coastal areas around or after 29/08-10Z. However, a combination of weak mid/upper forcing for upward vertical motion and relatively warm layers aloft appear to preclude an appreciable risk for convection capable of producing lightning. ..Kerr.. 12/29/2023 Read more

No Mesoscale Discussions are in effect as of Thu Dec 28 23:38:01 UTC 2023.

No watches are valid as of Thu Dec 28 23:38:01 UTC 2023.

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0351 PM CST Thu Dec 28 2023 Valid 301200Z - 051200Z Critical fire-weather conditions are not expected during the extended forecast period, though locally elevated conditions are possible over the southern High Plains on D4/Sunday. On D3/Saturday, a midlevel shortwave ridge will be in place over the southern Rockies, with enhanced west-northwest flow along the northern periphery of this feature. This will promote lee troughing/weak lee cyclogenesis and locally dry/breezy conditions across parts of the southern High Plains during the afternoon. Overall, a minimal overlap of dry/breezy conditions and marginal fuels should limit fire-weather concerns. Thereafter, a southern-stream jet max will track eastward from southern CA and overspread the southern Rockies on D4/Sunday. The strong westerly downslope flow will maintain a weak lee cyclone (ahead of an approaching cold front from the north) and favor dry/windy conditions across southeast NM into West TX. While locally elevated conditions are possible, marginal fuels should limit the potential for critical conditions. Elsewhere across the CONUS, fire-weather concerns appear minimal. ..Weinman.. 12/28/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more