Severe Storms

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1154 PM CST Mon Dec 30 2024 Valid 311200Z - 011200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PART OF THE CENTRAL APPALACHIANS AND MID-ATLANTIC... ...SUMMARY... Isolated severe thunderstorms, associated with marginally severe gusts, hail and possibly a brief tornado, are expected to develop today from the central Appalachians into the Mid-Atlantic. ...Central Appalachians/Mid-Atlantic... A negative-tilted mid-level trough will move eastward into the central Appalachian Mountains today, as a 90 to 100 knot mid-level jet moves through the northern Gulf Coast states. At the surface, a low will move through the Ohio Valley, as a warm front advances northward into the Mid-Atlantic. This afternoon, scattered thunderstorms are expected to develop near a cold pocket aloft associated with the mid-level low. In addition, a line of thunderstorms is forecast to develop in the central Appalachians, where lift will be enhanced by the left exit region of the mid-level jet. RAP forecast soundings across the central Appalachians by early afternoon have MUCAPE in the 300 to 500 J/kg range, and steepen low-level lapse rates to around 7 C/km. This should be enough for isolated severe gusts along the leading edge of the strongly-forced the line. In addition, afternoon forecast soundings in the Mid-Atlantic have 0-3 km storm-relative helicity in the 250 to 350 m2/s2 range suggesting that a marginal tornado threat will also be possible. Hail could also occur with cells embedded in the more organized parts of the line. The severe threat is expected to continue into the late afternoon, as the line of storms moves through the Mid-Atlantic region. ..Broyles/Thornton.. 12/31/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1154 PM CST Mon Dec 30 2024 Valid 311200Z - 011200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PART OF THE CENTRAL APPALACHIANS AND MID-ATLANTIC... ...SUMMARY... Isolated severe thunderstorms, associated with marginally severe gusts, hail and possibly a brief tornado, are expected to develop today from the central Appalachians into the Mid-Atlantic. ...Central Appalachians/Mid-Atlantic... A negative-tilted mid-level trough will move eastward into the central Appalachian Mountains today, as a 90 to 100 knot mid-level jet moves through the northern Gulf Coast states. At the surface, a low will move through the Ohio Valley, as a warm front advances northward into the Mid-Atlantic. This afternoon, scattered thunderstorms are expected to develop near a cold pocket aloft associated with the mid-level low. In addition, a line of thunderstorms is forecast to develop in the central Appalachians, where lift will be enhanced by the left exit region of the mid-level jet. RAP forecast soundings across the central Appalachians by early afternoon have MUCAPE in the 300 to 500 J/kg range, and steepen low-level lapse rates to around 7 C/km. This should be enough for isolated severe gusts along the leading edge of the strongly-forced the line. In addition, afternoon forecast soundings in the Mid-Atlantic have 0-3 km storm-relative helicity in the 250 to 350 m2/s2 range suggesting that a marginal tornado threat will also be possible. Hail could also occur with cells embedded in the more organized parts of the line. The severe threat is expected to continue into the late afternoon, as the line of storms moves through the Mid-Atlantic region. ..Broyles/Thornton.. 12/31/2024 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0656 PM CST Mon Dec 30 2024 Valid 310100Z - 311200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms will be possible tonight in parts of the mid Mississippi and lower Ohio Valleys, but no severe threat is expected. ...DISCUSSION... A shortwave trough, evident on water vapor imagery over the central U.S., will move eastward across the mid Mississippi Valley tonight. Isolated thunderstorm development is expected after midnight ahead of the trough over parts of the mid Mississippi and lower Ohio Valleys, where surface dewpoints will mostly be in the 40s F. RAP forecast soundings in the lower Ohio Valley later tonight suggest that a boundary layer temperature inversion will be in place, which will keep thunderstorms elevated in nature. Although the stronger cells could produce gusty winds, instability should be too weak for a severe threat. Elsewhere across the continental U.S., thunderstorms are not expected to develop through tonight. ..Broyles.. 12/31/2024 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0656 PM CST Mon Dec 30 2024 Valid 310100Z - 311200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms will be possible tonight in parts of the mid Mississippi and lower Ohio Valleys, but no severe threat is expected. ...DISCUSSION... A shortwave trough, evident on water vapor imagery over the central U.S., will move eastward across the mid Mississippi Valley tonight. Isolated thunderstorm development is expected after midnight ahead of the trough over parts of the mid Mississippi and lower Ohio Valleys, where surface dewpoints will mostly be in the 40s F. RAP forecast soundings in the lower Ohio Valley later tonight suggest that a boundary layer temperature inversion will be in place, which will keep thunderstorms elevated in nature. Although the stronger cells could produce gusty winds, instability should be too weak for a severe threat. Elsewhere across the continental U.S., thunderstorms are not expected to develop through tonight. ..Broyles.. 12/31/2024 Read more

No watches are valid as of Mon Dec 30 23:59:02 UTC 2024.

No Mesoscale Discussions are in effect as of Mon Dec 30 23:59:02 UTC 2024.

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0344 PM CST Mon Dec 30 2024 Valid 011200Z - 071200Z An upper-level ridge will build over the West late Day 3/Wednesday into Day 5/Friday while an upper-level trough deepens over the eastern US. An upper-level trough is forecast to move over the West late Day 5/Friday and Day 6/Saturday then over the southern and central Plains on Day 7/Sunday into Day 8/Monday. Dry conditions will persist for much of the southwest US and southern/central High Plains through the outlook period. ...Day 3/Wednesday - Day 4/Thursday: Southern California... A relatively isolated weak to moderate Santa Ana wind event will continue across of the Transverse Ranges into Day 4/Thursday evening. Locally critical winds/RH remain likely in the mountains and adjacent foothills of Ventura and western Los Angeles Counties, mostly on southern/ocean facing slopes. 40% probabilities have been maintained, but a Day 1/2 Critical area cannot be ruled out in future outlooks. Another Santa Ana wind event is possible starting on Day 7/Sunday and lasting through early next week. Forecast uncertainty precludes adding probabilities at this time, but if model trends hold, probabilities will be necessary in future outlooks. ...Day 6/Saturday - Day 7/Sunday: Southwest and southern High Plains... The trough forecast to move over the West on Day 5/Friday - Day 6/Saturday will likely lead to elevated/locally critical fire weather conditions across portions of the Southwest and southern High Plains on Day 6/Saturday - Day 7/Sunday. The timing and track of the upper-level trough are still somewhat uncertain, but the last few model runs seem to be coalescing around a solution. Future outlooks will likely introduce probabilities for critical fire weather this weekend across portions of the Southwest and southern High Plains. ..Nauslar.. 12/30/2024 ...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 0344 PM CST Mon Dec 30 2024 Valid 011200Z - 071200Z An upper-level ridge will build over the West late Day 3/Wednesday into Day 5/Friday while an upper-level trough deepens over the eastern US. An upper-level trough is forecast to move over the West late Day 5/Friday and Day 6/Saturday then over the southern and central Plains on Day 7/Sunday into Day 8/Monday. Dry conditions will persist for much of the southwest US and southern/central High Plains through the outlook period. ...Day 3/Wednesday - Day 4/Thursday: Southern California... A relatively isolated weak to moderate Santa Ana wind event will continue across of the Transverse Ranges into Day 4/Thursday evening. Locally critical winds/RH remain likely in the mountains and adjacent foothills of Ventura and western Los Angeles Counties, mostly on southern/ocean facing slopes. 40% probabilities have been maintained, but a Day 1/2 Critical area cannot be ruled out in future outlooks. Another Santa Ana wind event is possible starting on Day 7/Sunday and lasting through early next week. Forecast uncertainty precludes adding probabilities at this time, but if model trends hold, probabilities will be necessary in future outlooks. ...Day 6/Saturday - Day 7/Sunday: Southwest and southern High Plains... The trough forecast to move over the West on Day 5/Friday - Day 6/Saturday will likely lead to elevated/locally critical fire weather conditions across portions of the Southwest and southern High Plains on Day 6/Saturday - Day 7/Sunday. The timing and track of the upper-level trough are still somewhat uncertain, but the last few model runs seem to be coalescing around a solution. Future outlooks will likely introduce probabilities for critical fire weather this weekend across portions of the Southwest and southern High Plains. ..Nauslar.. 12/30/2024 ...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 0344 PM CST Mon Dec 30 2024 Valid 011200Z - 071200Z An upper-level ridge will build over the West late Day 3/Wednesday into Day 5/Friday while an upper-level trough deepens over the eastern US. An upper-level trough is forecast to move over the West late Day 5/Friday and Day 6/Saturday then over the southern and central Plains on Day 7/Sunday into Day 8/Monday. Dry conditions will persist for much of the southwest US and southern/central High Plains through the outlook period. ...Day 3/Wednesday - Day 4/Thursday: Southern California... A relatively isolated weak to moderate Santa Ana wind event will continue across of the Transverse Ranges into Day 4/Thursday evening. Locally critical winds/RH remain likely in the mountains and adjacent foothills of Ventura and western Los Angeles Counties, mostly on southern/ocean facing slopes. 40% probabilities have been maintained, but a Day 1/2 Critical area cannot be ruled out in future outlooks. Another Santa Ana wind event is possible starting on Day 7/Sunday and lasting through early next week. Forecast uncertainty precludes adding probabilities at this time, but if model trends hold, probabilities will be necessary in future outlooks. ...Day 6/Saturday - Day 7/Sunday: Southwest and southern High Plains... The trough forecast to move over the West on Day 5/Friday - Day 6/Saturday will likely lead to elevated/locally critical fire weather conditions across portions of the Southwest and southern High Plains on Day 6/Saturday - Day 7/Sunday. The timing and track of the upper-level trough are still somewhat uncertain, but the last few model runs seem to be coalescing around a solution. Future outlooks will likely introduce probabilities for critical fire weather this weekend across portions of the Southwest and southern High Plains. ..Nauslar.. 12/30/2024 ...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 0344 PM CST Mon Dec 30 2024 Valid 011200Z - 071200Z An upper-level ridge will build over the West late Day 3/Wednesday into Day 5/Friday while an upper-level trough deepens over the eastern US. An upper-level trough is forecast to move over the West late Day 5/Friday and Day 6/Saturday then over the southern and central Plains on Day 7/Sunday into Day 8/Monday. Dry conditions will persist for much of the southwest US and southern/central High Plains through the outlook period. ...Day 3/Wednesday - Day 4/Thursday: Southern California... A relatively isolated weak to moderate Santa Ana wind event will continue across of the Transverse Ranges into Day 4/Thursday evening. Locally critical winds/RH remain likely in the mountains and adjacent foothills of Ventura and western Los Angeles Counties, mostly on southern/ocean facing slopes. 40% probabilities have been maintained, but a Day 1/2 Critical area cannot be ruled out in future outlooks. Another Santa Ana wind event is possible starting on Day 7/Sunday and lasting through early next week. Forecast uncertainty precludes adding probabilities at this time, but if model trends hold, probabilities will be necessary in future outlooks. ...Day 6/Saturday - Day 7/Sunday: Southwest and southern High Plains... The trough forecast to move over the West on Day 5/Friday - Day 6/Saturday will likely lead to elevated/locally critical fire weather conditions across portions of the Southwest and southern High Plains on Day 6/Saturday - Day 7/Sunday. The timing and track of the upper-level trough are still somewhat uncertain, but the last few model runs seem to be coalescing around a solution. Future outlooks will likely introduce probabilities for critical fire weather this weekend across portions of the Southwest and southern High Plains. ..Nauslar.. 12/30/2024 ...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 0344 PM CST Mon Dec 30 2024 Valid 011200Z - 071200Z An upper-level ridge will build over the West late Day 3/Wednesday into Day 5/Friday while an upper-level trough deepens over the eastern US. An upper-level trough is forecast to move over the West late Day 5/Friday and Day 6/Saturday then over the southern and central Plains on Day 7/Sunday into Day 8/Monday. Dry conditions will persist for much of the southwest US and southern/central High Plains through the outlook period. ...Day 3/Wednesday - Day 4/Thursday: Southern California... A relatively isolated weak to moderate Santa Ana wind event will continue across of the Transverse Ranges into Day 4/Thursday evening. Locally critical winds/RH remain likely in the mountains and adjacent foothills of Ventura and western Los Angeles Counties, mostly on southern/ocean facing slopes. 40% probabilities have been maintained, but a Day 1/2 Critical area cannot be ruled out in future outlooks. Another Santa Ana wind event is possible starting on Day 7/Sunday and lasting through early next week. Forecast uncertainty precludes adding probabilities at this time, but if model trends hold, probabilities will be necessary in future outlooks. ...Day 6/Saturday - Day 7/Sunday: Southwest and southern High Plains... The trough forecast to move over the West on Day 5/Friday - Day 6/Saturday will likely lead to elevated/locally critical fire weather conditions across portions of the Southwest and southern High Plains on Day 6/Saturday - Day 7/Sunday. The timing and track of the upper-level trough are still somewhat uncertain, but the last few model runs seem to be coalescing around a solution. Future outlooks will likely introduce probabilities for critical fire weather this weekend across portions of the Southwest and southern High Plains. ..Nauslar.. 12/30/2024 ...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 0344 PM CST Mon Dec 30 2024 Valid 011200Z - 071200Z An upper-level ridge will build over the West late Day 3/Wednesday into Day 5/Friday while an upper-level trough deepens over the eastern US. An upper-level trough is forecast to move over the West late Day 5/Friday and Day 6/Saturday then over the southern and central Plains on Day 7/Sunday into Day 8/Monday. Dry conditions will persist for much of the southwest US and southern/central High Plains through the outlook period. ...Day 3/Wednesday - Day 4/Thursday: Southern California... A relatively isolated weak to moderate Santa Ana wind event will continue across of the Transverse Ranges into Day 4/Thursday evening. Locally critical winds/RH remain likely in the mountains and adjacent foothills of Ventura and western Los Angeles Counties, mostly on southern/ocean facing slopes. 40% probabilities have been maintained, but a Day 1/2 Critical area cannot be ruled out in future outlooks. Another Santa Ana wind event is possible starting on Day 7/Sunday and lasting through early next week. Forecast uncertainty precludes adding probabilities at this time, but if model trends hold, probabilities will be necessary in future outlooks. ...Day 6/Saturday - Day 7/Sunday: Southwest and southern High Plains... The trough forecast to move over the West on Day 5/Friday - Day 6/Saturday will likely lead to elevated/locally critical fire weather conditions across portions of the Southwest and southern High Plains on Day 6/Saturday - Day 7/Sunday. The timing and track of the upper-level trough are still somewhat uncertain, but the last few model runs seem to be coalescing around a solution. Future outlooks will likely introduce probabilities for critical fire weather this weekend across portions of the Southwest and southern High Plains. ..Nauslar.. 12/30/2024 ...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 0141 PM CST Mon Dec 30 2024 Valid 302000Z - 311200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected through tonight. ...20z Update... The previous forecast remains on track with no changes required. Latest guidance continues to suggest that a swath of weak thunderstorms will overspread the OH River Valley late tonight into early Tuesday morning. Some solutions, notably recent runs of the HRRR and RAP, hint that a corridor of surface-based convection may develop from northwest KY/southern IN into north-central KY/southwest OH between 07-12 UTC along the primary surface trough. SBCAPE/lifted indices will remain fairly limited (250-500 J/kg and -1 to -2 C respectively) and modulate overall convective intensity; however, 40 knot, nearly uni-directional flow within the 0-1 km layer may promote sporadic damaging wind gusts during the pre-dawn hours. Consideration was given for 5% wind probabilities, but the overall convective signal in recent guidance remains too limited to garner sufficient confidence in this potential threat. ..Moore.. 12/30/2024 .PREV DISCUSSION... /ISSUED 1022 AM CST Mon Dec 30 2024/ ...OH Valley tonight... An 80-100 knot mid-level jet max will move quickly eastward across the central Plains today, and into the mid MS Valley tonight. Strong cyclogenesis will occur in advance of this system over MO/IL, with the primary baroclinic zone sweeping across AR into KY/TN. Strengthening southerly low-level winds in the warm sector of the deepening low will result in broad low-level warm/moist advection, and perhaps just enough CAPE for a few thunderstorms late tonight across the lower and middle OH Valley. Forecast soundings show impressive low-level shear profiles, but thermodynamics are quite weak with surface-based convection unlikely. Thus the severe threat is low. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0141 PM CST Mon Dec 30 2024 Valid 302000Z - 311200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected through tonight. ...20z Update... The previous forecast remains on track with no changes required. Latest guidance continues to suggest that a swath of weak thunderstorms will overspread the OH River Valley late tonight into early Tuesday morning. Some solutions, notably recent runs of the HRRR and RAP, hint that a corridor of surface-based convection may develop from northwest KY/southern IN into north-central KY/southwest OH between 07-12 UTC along the primary surface trough. SBCAPE/lifted indices will remain fairly limited (250-500 J/kg and -1 to -2 C respectively) and modulate overall convective intensity; however, 40 knot, nearly uni-directional flow within the 0-1 km layer may promote sporadic damaging wind gusts during the pre-dawn hours. Consideration was given for 5% wind probabilities, but the overall convective signal in recent guidance remains too limited to garner sufficient confidence in this potential threat. ..Moore.. 12/30/2024 .PREV DISCUSSION... /ISSUED 1022 AM CST Mon Dec 30 2024/ ...OH Valley tonight... An 80-100 knot mid-level jet max will move quickly eastward across the central Plains today, and into the mid MS Valley tonight. Strong cyclogenesis will occur in advance of this system over MO/IL, with the primary baroclinic zone sweeping across AR into KY/TN. Strengthening southerly low-level winds in the warm sector of the deepening low will result in broad low-level warm/moist advection, and perhaps just enough CAPE for a few thunderstorms late tonight across the lower and middle OH Valley. Forecast soundings show impressive low-level shear profiles, but thermodynamics are quite weak with surface-based convection unlikely. Thus the severe threat is low. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0141 PM CST Mon Dec 30 2024 Valid 302000Z - 311200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected through tonight. ...20z Update... The previous forecast remains on track with no changes required. Latest guidance continues to suggest that a swath of weak thunderstorms will overspread the OH River Valley late tonight into early Tuesday morning. Some solutions, notably recent runs of the HRRR and RAP, hint that a corridor of surface-based convection may develop from northwest KY/southern IN into north-central KY/southwest OH between 07-12 UTC along the primary surface trough. SBCAPE/lifted indices will remain fairly limited (250-500 J/kg and -1 to -2 C respectively) and modulate overall convective intensity; however, 40 knot, nearly uni-directional flow within the 0-1 km layer may promote sporadic damaging wind gusts during the pre-dawn hours. Consideration was given for 5% wind probabilities, but the overall convective signal in recent guidance remains too limited to garner sufficient confidence in this potential threat. ..Moore.. 12/30/2024 .PREV DISCUSSION... /ISSUED 1022 AM CST Mon Dec 30 2024/ ...OH Valley tonight... An 80-100 knot mid-level jet max will move quickly eastward across the central Plains today, and into the mid MS Valley tonight. Strong cyclogenesis will occur in advance of this system over MO/IL, with the primary baroclinic zone sweeping across AR into KY/TN. Strengthening southerly low-level winds in the warm sector of the deepening low will result in broad low-level warm/moist advection, and perhaps just enough CAPE for a few thunderstorms late tonight across the lower and middle OH Valley. Forecast soundings show impressive low-level shear profiles, but thermodynamics are quite weak with surface-based convection unlikely. Thus the severe threat is low. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0141 PM CST Mon Dec 30 2024 Valid 302000Z - 311200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected through tonight. ...20z Update... The previous forecast remains on track with no changes required. Latest guidance continues to suggest that a swath of weak thunderstorms will overspread the OH River Valley late tonight into early Tuesday morning. Some solutions, notably recent runs of the HRRR and RAP, hint that a corridor of surface-based convection may develop from northwest KY/southern IN into north-central KY/southwest OH between 07-12 UTC along the primary surface trough. SBCAPE/lifted indices will remain fairly limited (250-500 J/kg and -1 to -2 C respectively) and modulate overall convective intensity; however, 40 knot, nearly uni-directional flow within the 0-1 km layer may promote sporadic damaging wind gusts during the pre-dawn hours. Consideration was given for 5% wind probabilities, but the overall convective signal in recent guidance remains too limited to garner sufficient confidence in this potential threat. ..Moore.. 12/30/2024 .PREV DISCUSSION... /ISSUED 1022 AM CST Mon Dec 30 2024/ ...OH Valley tonight... An 80-100 knot mid-level jet max will move quickly eastward across the central Plains today, and into the mid MS Valley tonight. Strong cyclogenesis will occur in advance of this system over MO/IL, with the primary baroclinic zone sweeping across AR into KY/TN. Strengthening southerly low-level winds in the warm sector of the deepening low will result in broad low-level warm/moist advection, and perhaps just enough CAPE for a few thunderstorms late tonight across the lower and middle OH Valley. Forecast soundings show impressive low-level shear profiles, but thermodynamics are quite weak with surface-based convection unlikely. Thus the severe threat is low. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0141 PM CST Mon Dec 30 2024 Valid 302000Z - 311200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected through tonight. ...20z Update... The previous forecast remains on track with no changes required. Latest guidance continues to suggest that a swath of weak thunderstorms will overspread the OH River Valley late tonight into early Tuesday morning. Some solutions, notably recent runs of the HRRR and RAP, hint that a corridor of surface-based convection may develop from northwest KY/southern IN into north-central KY/southwest OH between 07-12 UTC along the primary surface trough. SBCAPE/lifted indices will remain fairly limited (250-500 J/kg and -1 to -2 C respectively) and modulate overall convective intensity; however, 40 knot, nearly uni-directional flow within the 0-1 km layer may promote sporadic damaging wind gusts during the pre-dawn hours. Consideration was given for 5% wind probabilities, but the overall convective signal in recent guidance remains too limited to garner sufficient confidence in this potential threat. ..Moore.. 12/30/2024 .PREV DISCUSSION... /ISSUED 1022 AM CST Mon Dec 30 2024/ ...OH Valley tonight... An 80-100 knot mid-level jet max will move quickly eastward across the central Plains today, and into the mid MS Valley tonight. Strong cyclogenesis will occur in advance of this system over MO/IL, with the primary baroclinic zone sweeping across AR into KY/TN. Strengthening southerly low-level winds in the warm sector of the deepening low will result in broad low-level warm/moist advection, and perhaps just enough CAPE for a few thunderstorms late tonight across the lower and middle OH Valley. Forecast soundings show impressive low-level shear profiles, but thermodynamics are quite weak with surface-based convection unlikely. Thus the severe threat is low. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0141 PM CST Mon Dec 30 2024 Valid 302000Z - 311200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected through tonight. ...20z Update... The previous forecast remains on track with no changes required. Latest guidance continues to suggest that a swath of weak thunderstorms will overspread the OH River Valley late tonight into early Tuesday morning. Some solutions, notably recent runs of the HRRR and RAP, hint that a corridor of surface-based convection may develop from northwest KY/southern IN into north-central KY/southwest OH between 07-12 UTC along the primary surface trough. SBCAPE/lifted indices will remain fairly limited (250-500 J/kg and -1 to -2 C respectively) and modulate overall convective intensity; however, 40 knot, nearly uni-directional flow within the 0-1 km layer may promote sporadic damaging wind gusts during the pre-dawn hours. Consideration was given for 5% wind probabilities, but the overall convective signal in recent guidance remains too limited to garner sufficient confidence in this potential threat. ..Moore.. 12/30/2024 .PREV DISCUSSION... /ISSUED 1022 AM CST Mon Dec 30 2024/ ...OH Valley tonight... An 80-100 knot mid-level jet max will move quickly eastward across the central Plains today, and into the mid MS Valley tonight. Strong cyclogenesis will occur in advance of this system over MO/IL, with the primary baroclinic zone sweeping across AR into KY/TN. Strengthening southerly low-level winds in the warm sector of the deepening low will result in broad low-level warm/moist advection, and perhaps just enough CAPE for a few thunderstorms late tonight across the lower and middle OH Valley. Forecast soundings show impressive low-level shear profiles, but thermodynamics are quite weak with surface-based convection unlikely. Thus the severe threat is low. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0141 PM CST Mon Dec 30 2024 Valid 302000Z - 311200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected through tonight. ...20z Update... The previous forecast remains on track with no changes required. Latest guidance continues to suggest that a swath of weak thunderstorms will overspread the OH River Valley late tonight into early Tuesday morning. Some solutions, notably recent runs of the HRRR and RAP, hint that a corridor of surface-based convection may develop from northwest KY/southern IN into north-central KY/southwest OH between 07-12 UTC along the primary surface trough. SBCAPE/lifted indices will remain fairly limited (250-500 J/kg and -1 to -2 C respectively) and modulate overall convective intensity; however, 40 knot, nearly uni-directional flow within the 0-1 km layer may promote sporadic damaging wind gusts during the pre-dawn hours. Consideration was given for 5% wind probabilities, but the overall convective signal in recent guidance remains too limited to garner sufficient confidence in this potential threat. ..Moore.. 12/30/2024 .PREV DISCUSSION... /ISSUED 1022 AM CST Mon Dec 30 2024/ ...OH Valley tonight... An 80-100 knot mid-level jet max will move quickly eastward across the central Plains today, and into the mid MS Valley tonight. Strong cyclogenesis will occur in advance of this system over MO/IL, with the primary baroclinic zone sweeping across AR into KY/TN. Strengthening southerly low-level winds in the warm sector of the deepening low will result in broad low-level warm/moist advection, and perhaps just enough CAPE for a few thunderstorms late tonight across the lower and middle OH Valley. Forecast soundings show impressive low-level shear profiles, but thermodynamics are quite weak with surface-based convection unlikely. Thus the severe threat is low. Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0104 PM CST Mon Dec 30 2024 Valid 011200Z - 021200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are not expected Wednesday. ...Synopsis... A broad area of west/northwesterly mid/upper flow will overspread much of the CONUS on Wednesday, with a more amplified upper trough beginning to develop late in the period over the West. At the surface, a deep surface low will lift northeast across the Northeast, with surface high pressure building in its wake over much of the U.S. Dry and stable conditions will preclude thunderstorm potential. ..Leitman.. 12/30/2024 Read more