Severe Storms

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0147 AM CDT Mon Sep 23 2019 Valid 241200Z - 251200Z ...Synopsis... A closed mid/upper-level low is forecast to gradually shift from the Desert Southwest to Baja California through Day 2/Tuesday. ...Southern California... Pockets of elevated to locally critical fire weather conditions will likely be ongoing early Day 2/Tuesday across the mountains of Ventura, Los Angeles, and Santa Barbara Counties as increasing offshore surface winds overlap areas with poor overnight RH recoveries. While winds are forecast to weaken through the day as upper-level support associated with the aforementioned upper low shifts away from the area, elevated fire weather conditions should remain as RH values continue to decrease. At least locally elevated fire weather conditions are possible into Day 2/Tuesday night as RH recoveries remain poor amidst breezy winds. ...Northern California... Pockets of elevated to locally critical fire weather conditions will likely be ongoing across the higher elevations (e.g., > 1 kft) of the North/East Bay Hills, the Diablo Range, the Northern Coast Mountains, and the western slopes of the Northern Sierra's and adjacent foothills Day 2/Tuesday morning as poor overnight RH recoveries occur in conjunction with gusty surface winds. By afternoon, elevated fire weather conditions should spread to the lower elevations of the Sacramento Valley as sustained surface winds of around 15 mph develop in conjunction with near critical RH values. At least locally elevated fire weather conditions are possible at higher elevations (e.g., > 1 kft) into Day 2/Tuesday night as RH recoveries remain poor amidst breezy winds. ..Elliott.. 09/23/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0145 AM CDT Mon Sep 23 2019 Valid 231200Z - 241200Z ...Synopsis... A strong mid/upper-level trough is forecast to become cutoff from the main flow as it moves from the Great Basin southeastward to the Southwest Desert through tonight. As this occurs, an area of enhanced northerly mid-level flow -- located on the west side of the trough -- will overspread much of California as it shifts southward through the day. ...Northern California... Breezy northerly low-level flow is forecast to develop during the early afternoon across portions of the Sacramento Valley and adjacent Coastal Mountains behind the aforementioned mid-level trough. While sustained surface winds are forecast to generally remain around 10-20 mph (locally greater), wind gusts of 30-40 mph are possible. Elevated to locally critical fire weather conditions are likely as these winds overlap minimum RH values of 15-20% (locally lower) and at least marginally receptive fuels. Poor overnight RH recoveries (15-25%) and lingering breezy/gusty northerly winds should continue to foster elevated to locally critical fire weather conditions late this evening and into tonight across the higher elevations (e.g., > 1 kft) of the North/East Bay Hills, the Diablo Range, and the Northern Coast Mountains. Additionally, gusty northeasterly downslope winds (gusts up to 50 mph) on the western slopes of the Northern Sierra's and adjacent foothills should promote elevated to locally critical fire weather conditions late this evening/tonight amidst poor overnight RH recoveries (around 20-25%). ...Southern California... A dry offshore low-level flow is forecast to increase late tonight over the mountains of Ventura, Los Angeles, and Santa Barbara Counties as the aforementioned area of enhanced mid-level flow overspreads the area. While the timing of the stronger winds and RH reductions remains somewhat uncertain, at least a few hours of elevated to locally critical fire weather conditions are possible late tonight. ..Elliott.. 09/23/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0145 AM CDT Mon Sep 23 2019 Valid 231200Z - 241200Z ...Synopsis... A strong mid/upper-level trough is forecast to become cutoff from the main flow as it moves from the Great Basin southeastward to the Southwest Desert through tonight. As this occurs, an area of enhanced northerly mid-level flow -- located on the west side of the trough -- will overspread much of California as it shifts southward through the day. ...Northern California... Breezy northerly low-level flow is forecast to develop during the early afternoon across portions of the Sacramento Valley and adjacent Coastal Mountains behind the aforementioned mid-level trough. While sustained surface winds are forecast to generally remain around 10-20 mph (locally greater), wind gusts of 30-40 mph are possible. Elevated to locally critical fire weather conditions are likely as these winds overlap minimum RH values of 15-20% (locally lower) and at least marginally receptive fuels. Poor overnight RH recoveries (15-25%) and lingering breezy/gusty northerly winds should continue to foster elevated to locally critical fire weather conditions late this evening and into tonight across the higher elevations (e.g., > 1 kft) of the North/East Bay Hills, the Diablo Range, and the Northern Coast Mountains. Additionally, gusty northeasterly downslope winds (gusts up to 50 mph) on the western slopes of the Northern Sierra's and adjacent foothills should promote elevated to locally critical fire weather conditions late this evening/tonight amidst poor overnight RH recoveries (around 20-25%). ...Southern California... A dry offshore low-level flow is forecast to increase late tonight over the mountains of Ventura, Los Angeles, and Santa Barbara Counties as the aforementioned area of enhanced mid-level flow overspreads the area. While the timing of the stronger winds and RH reductions remains somewhat uncertain, at least a few hours of elevated to locally critical fire weather conditions are possible late tonight. ..Elliott.. 09/23/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0145 AM CDT Mon Sep 23 2019 Valid 231200Z - 241200Z ...Synopsis... A strong mid/upper-level trough is forecast to become cutoff from the main flow as it moves from the Great Basin southeastward to the Southwest Desert through tonight. As this occurs, an area of enhanced northerly mid-level flow -- located on the west side of the trough -- will overspread much of California as it shifts southward through the day. ...Northern California... Breezy northerly low-level flow is forecast to develop during the early afternoon across portions of the Sacramento Valley and adjacent Coastal Mountains behind the aforementioned mid-level trough. While sustained surface winds are forecast to generally remain around 10-20 mph (locally greater), wind gusts of 30-40 mph are possible. Elevated to locally critical fire weather conditions are likely as these winds overlap minimum RH values of 15-20% (locally lower) and at least marginally receptive fuels. Poor overnight RH recoveries (15-25%) and lingering breezy/gusty northerly winds should continue to foster elevated to locally critical fire weather conditions late this evening and into tonight across the higher elevations (e.g., > 1 kft) of the North/East Bay Hills, the Diablo Range, and the Northern Coast Mountains. Additionally, gusty northeasterly downslope winds (gusts up to 50 mph) on the western slopes of the Northern Sierra's and adjacent foothills should promote elevated to locally critical fire weather conditions late this evening/tonight amidst poor overnight RH recoveries (around 20-25%). ...Southern California... A dry offshore low-level flow is forecast to increase late tonight over the mountains of Ventura, Los Angeles, and Santa Barbara Counties as the aforementioned area of enhanced mid-level flow overspreads the area. While the timing of the stronger winds and RH reductions remains somewhat uncertain, at least a few hours of elevated to locally critical fire weather conditions are possible late tonight. ..Elliott.. 09/23/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 AM CDT Mon Sep 23 2019 Valid 241200Z - 251200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER EASTERN NEBRASKA...IOWA...SOUTHERN MINNESOTA...AND WESTERN WISCONSIN... ...SUMMARY... Severe storms are possible Tuesday across much of Iowa, western Wisconsin, eastern Nebraska, and southern Minnesota, with isolated storms from parts of the central Plains to the Upper Great Lakes. A few strong storms may linger over southern Arizona as well. ...Synopsis... Strong cyclonic flow aloft will broaden over the north-central U.S. with the nose of an upper level jet developing across the Dakotas, MN, and WI. Cooling aloft will coincide with this jet max which will work with a cold front to provide a focus for severe storms. The front will stretch roughly from southern MN into eastern NE by 00Z, with increasing low-level moisture aiding destabilization. The tail end of this front will stall over KS, where a moist and unstable air mass will remain. To the west, an upper low will continue dropping south across western AZ and into the northern Gulf of CA, with cool temperatures aloft and antecedent moisture maintaining a risk of thunderstorms mainly over southern AZ. ...IA/MN/WI area, and NE/KS... Southwest surface winds will increase throughout the period, with 30-40 kt at 850 mb aiding moisture transport ahead of the cold front. At least mid 60s F dewpoints are expected to spread north into southern MN, with upper 60s F possible depending on evapotranspiration and mixing. This should yield at least 2000 J/kg MUCAPE, with steep lapse rates aloft. Storms are expected to form late in the day along the front where the cap will be breached due to lift. The increasing west/northwest winds aloft will result in favorable shear vector orientation along the front for supercells, a few of which may produce very large hail. A tornado or two is possible as well with effective SRH increasing above 200 m2/s2. The main limiting factors to an Enhanced Risk category are expected storms coverage due to capping and boundary layer moisture quality. Isolated severe storms are possible as far southwest as eastern Nebraska along the front, where dewpoints are likely to be higher, though large-scale lift will not be as favorable. Isolated severe storms capable of hail or wind may also occur over central KS during the afternoon as heating will be strong over southwest KS ahead of the boundary. A storm or two may approach northern OK during the evening. ...Southern AZ... Scattered thunderstorms are likely to be ongoing over parts of southern AZ, and cool temperatures aloft may support a few strong storms with gusty winds or small hail. Additional storms cannot be ruled out during the afternoon with heating, while temperatures aloft remain cool. By this time, shear will be weaker, thus widespread severe is not expected. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% SIG - Slight ..Jewell.. 09/23/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 AM CDT Mon Sep 23 2019 Valid 241200Z - 251200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER EASTERN NEBRASKA...IOWA...SOUTHERN MINNESOTA...AND WESTERN WISCONSIN... ...SUMMARY... Severe storms are possible Tuesday across much of Iowa, western Wisconsin, eastern Nebraska, and southern Minnesota, with isolated storms from parts of the central Plains to the Upper Great Lakes. A few strong storms may linger over southern Arizona as well. ...Synopsis... Strong cyclonic flow aloft will broaden over the north-central U.S. with the nose of an upper level jet developing across the Dakotas, MN, and WI. Cooling aloft will coincide with this jet max which will work with a cold front to provide a focus for severe storms. The front will stretch roughly from southern MN into eastern NE by 00Z, with increasing low-level moisture aiding destabilization. The tail end of this front will stall over KS, where a moist and unstable air mass will remain. To the west, an upper low will continue dropping south across western AZ and into the northern Gulf of CA, with cool temperatures aloft and antecedent moisture maintaining a risk of thunderstorms mainly over southern AZ. ...IA/MN/WI area, and NE/KS... Southwest surface winds will increase throughout the period, with 30-40 kt at 850 mb aiding moisture transport ahead of the cold front. At least mid 60s F dewpoints are expected to spread north into southern MN, with upper 60s F possible depending on evapotranspiration and mixing. This should yield at least 2000 J/kg MUCAPE, with steep lapse rates aloft. Storms are expected to form late in the day along the front where the cap will be breached due to lift. The increasing west/northwest winds aloft will result in favorable shear vector orientation along the front for supercells, a few of which may produce very large hail. A tornado or two is possible as well with effective SRH increasing above 200 m2/s2. The main limiting factors to an Enhanced Risk category are expected storms coverage due to capping and boundary layer moisture quality. Isolated severe storms are possible as far southwest as eastern Nebraska along the front, where dewpoints are likely to be higher, though large-scale lift will not be as favorable. Isolated severe storms capable of hail or wind may also occur over central KS during the afternoon as heating will be strong over southwest KS ahead of the boundary. A storm or two may approach northern OK during the evening. ...Southern AZ... Scattered thunderstorms are likely to be ongoing over parts of southern AZ, and cool temperatures aloft may support a few strong storms with gusty winds or small hail. Additional storms cannot be ruled out during the afternoon with heating, while temperatures aloft remain cool. By this time, shear will be weaker, thus widespread severe is not expected. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% SIG - Slight ..Jewell.. 09/23/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 AM CDT Mon Sep 23 2019 Valid 241200Z - 251200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER EASTERN NEBRASKA...IOWA...SOUTHERN MINNESOTA...AND WESTERN WISCONSIN... ...SUMMARY... Severe storms are possible Tuesday across much of Iowa, western Wisconsin, eastern Nebraska, and southern Minnesota, with isolated storms from parts of the central Plains to the Upper Great Lakes. A few strong storms may linger over southern Arizona as well. ...Synopsis... Strong cyclonic flow aloft will broaden over the north-central U.S. with the nose of an upper level jet developing across the Dakotas, MN, and WI. Cooling aloft will coincide with this jet max which will work with a cold front to provide a focus for severe storms. The front will stretch roughly from southern MN into eastern NE by 00Z, with increasing low-level moisture aiding destabilization. The tail end of this front will stall over KS, where a moist and unstable air mass will remain. To the west, an upper low will continue dropping south across western AZ and into the northern Gulf of CA, with cool temperatures aloft and antecedent moisture maintaining a risk of thunderstorms mainly over southern AZ. ...IA/MN/WI area, and NE/KS... Southwest surface winds will increase throughout the period, with 30-40 kt at 850 mb aiding moisture transport ahead of the cold front. At least mid 60s F dewpoints are expected to spread north into southern MN, with upper 60s F possible depending on evapotranspiration and mixing. This should yield at least 2000 J/kg MUCAPE, with steep lapse rates aloft. Storms are expected to form late in the day along the front where the cap will be breached due to lift. The increasing west/northwest winds aloft will result in favorable shear vector orientation along the front for supercells, a few of which may produce very large hail. A tornado or two is possible as well with effective SRH increasing above 200 m2/s2. The main limiting factors to an Enhanced Risk category are expected storms coverage due to capping and boundary layer moisture quality. Isolated severe storms are possible as far southwest as eastern Nebraska along the front, where dewpoints are likely to be higher, though large-scale lift will not be as favorable. Isolated severe storms capable of hail or wind may also occur over central KS during the afternoon as heating will be strong over southwest KS ahead of the boundary. A storm or two may approach northern OK during the evening. ...Southern AZ... Scattered thunderstorms are likely to be ongoing over parts of southern AZ, and cool temperatures aloft may support a few strong storms with gusty winds or small hail. Additional storms cannot be ruled out during the afternoon with heating, while temperatures aloft remain cool. By this time, shear will be weaker, thus widespread severe is not expected. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% SIG - Slight ..Jewell.. 09/23/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1234 AM CDT Mon Sep 23 2019 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE DESERT SOUTHWEST... ...SUMMARY... Thunderstorms with wind damage and isolated large hail will be possible today across parts of Arizona. Storms with a few strong wind gusts will be possible in parts of the Northeast. ...Desert Southwest... An upper-level low will dig southward across the Desert Southwest today. At the surface, a low will deepen across far southeastern California as a moist airmass advects slowly northward across southwestern Arizona. Surface dewpoints will reach the upper 60s and lower 70s F across parts of southwest Arizona where moderate instability should be in place by midday. Model forecasts suggest scattered thunderstorms will develop across south-central Arizona during the afternoon with convection spreading east-northeastward into north-central Arizona by early evening. RAP forecast soundings in the 21Z to 00Z timeframe across south-central Arizona show MLCAPE values reaching the 1500 to 2500 J/kg range. Wind profiles show substantial speed shear in the low to mid-levels with 850 to 500 mb lapse rates around 7.0 c/km. This should support the development of supercells with isolated large hail and wind damage. If cells can congeal into a bowing line segment, then the more dominant threat could transition toward wind damage by early evening. ...Northeast... An upper-level trough will move across the lower Great Lakes region today as southwest mid-level flow remains over much of the Northeast. At the surface, a low will develop across southern Quebec as a corridor of maximized low-level moisture sets up ahead of a cold front moving southeastward into the Northeast. Scattered thunderstorms are forecast to develop this afternoon along and ahead of the front across western Pennsylvania, New York and western New England. Surface dewpoints in the mid 60s F will contribute to weak destabilization ahead of the front. In addition, strong deep-layer shear will be present making condition supportive of an isolated severe threat. Short multicell line segments should be able to produce a few marginally severe wind gusts this afternoon especially as low-level lapse rates become maximized. ..Broyles/Elliott.. 09/23/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1234 AM CDT Mon Sep 23 2019 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE DESERT SOUTHWEST... ...SUMMARY... Thunderstorms with wind damage and isolated large hail will be possible today across parts of Arizona. Storms with a few strong wind gusts will be possible in parts of the Northeast. ...Desert Southwest... An upper-level low will dig southward across the Desert Southwest today. At the surface, a low will deepen across far southeastern California as a moist airmass advects slowly northward across southwestern Arizona. Surface dewpoints will reach the upper 60s and lower 70s F across parts of southwest Arizona where moderate instability should be in place by midday. Model forecasts suggest scattered thunderstorms will develop across south-central Arizona during the afternoon with convection spreading east-northeastward into north-central Arizona by early evening. RAP forecast soundings in the 21Z to 00Z timeframe across south-central Arizona show MLCAPE values reaching the 1500 to 2500 J/kg range. Wind profiles show substantial speed shear in the low to mid-levels with 850 to 500 mb lapse rates around 7.0 c/km. This should support the development of supercells with isolated large hail and wind damage. If cells can congeal into a bowing line segment, then the more dominant threat could transition toward wind damage by early evening. ...Northeast... An upper-level trough will move across the lower Great Lakes region today as southwest mid-level flow remains over much of the Northeast. At the surface, a low will develop across southern Quebec as a corridor of maximized low-level moisture sets up ahead of a cold front moving southeastward into the Northeast. Scattered thunderstorms are forecast to develop this afternoon along and ahead of the front across western Pennsylvania, New York and western New England. Surface dewpoints in the mid 60s F will contribute to weak destabilization ahead of the front. In addition, strong deep-layer shear will be present making condition supportive of an isolated severe threat. Short multicell line segments should be able to produce a few marginally severe wind gusts this afternoon especially as low-level lapse rates become maximized. ..Broyles/Elliott.. 09/23/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1234 AM CDT Mon Sep 23 2019 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE DESERT SOUTHWEST... ...SUMMARY... Thunderstorms with wind damage and isolated large hail will be possible today across parts of Arizona. Storms with a few strong wind gusts will be possible in parts of the Northeast. ...Desert Southwest... An upper-level low will dig southward across the Desert Southwest today. At the surface, a low will deepen across far southeastern California as a moist airmass advects slowly northward across southwestern Arizona. Surface dewpoints will reach the upper 60s and lower 70s F across parts of southwest Arizona where moderate instability should be in place by midday. Model forecasts suggest scattered thunderstorms will develop across south-central Arizona during the afternoon with convection spreading east-northeastward into north-central Arizona by early evening. RAP forecast soundings in the 21Z to 00Z timeframe across south-central Arizona show MLCAPE values reaching the 1500 to 2500 J/kg range. Wind profiles show substantial speed shear in the low to mid-levels with 850 to 500 mb lapse rates around 7.0 c/km. This should support the development of supercells with isolated large hail and wind damage. If cells can congeal into a bowing line segment, then the more dominant threat could transition toward wind damage by early evening. ...Northeast... An upper-level trough will move across the lower Great Lakes region today as southwest mid-level flow remains over much of the Northeast. At the surface, a low will develop across southern Quebec as a corridor of maximized low-level moisture sets up ahead of a cold front moving southeastward into the Northeast. Scattered thunderstorms are forecast to develop this afternoon along and ahead of the front across western Pennsylvania, New York and western New England. Surface dewpoints in the mid 60s F will contribute to weak destabilization ahead of the front. In addition, strong deep-layer shear will be present making condition supportive of an isolated severe threat. Short multicell line segments should be able to produce a few marginally severe wind gusts this afternoon especially as low-level lapse rates become maximized. ..Broyles/Elliott.. 09/23/2019 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0742 PM CDT Sun Sep 22 2019 Valid 230100Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHERN PLAINS AND OZARKS... ...SUMMARY... Marginally severe wind gusts will be possible over the next few hours this evening from central Oklahoma northeastward into central Missouri. ...Southern Plains/Ozarks... The latest water vapor imagery shows west southwesterly mid-level flow over the southern Plains and mid Mississippi Valley. At the surface, a cold front is moving southeastward across central Oklahoma and north-central Missouri. Thunderstorms are ongoing just ahead of the front. Surface dewpoints ahead of the front are generally in the lower 70s F which is contributing to an axis of moderate instability (MLCAPE 1000 to 1500 J/kg). This combined with 35 to 40 kt of 0-6 km shear evident on regional WSR-88D VWPs should be sufficient for a marginal severe threat this evening with strong wind gusts possible. ..Broyles.. 09/23/2019 Read more

No watches are valid as of Sun Sep 22 22:32:02 UTC 2019.

No Mesoscale Discussions are in effect as of Sun Sep 22 22:32:02 UTC 2019.

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Sun Sep 22 2019 Valid 222000Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS EXTENDING FROM PARTS OF OKLAHOMA NORTHEASTWARD TO INDIANA... ...SUMMARY... Isolated damaging winds, and perhaps a tornado or two, will remain possible through this evening from parts of Oklahoma to Indiana. ...20Z Update... No changes have been made to the Marginal Risk extending from central OK northeastward to IL and far northwestern IN. A broad area of persistent rain showers across parts of MO into IL has hampered diurnal heating and the development of instability across this area. Relatively better, but still limited, severe potential may exist in a narrow corridor from parts of northern/central OK into southeastern KS and far western MO ahead of a surface cold front. MLCAPE around 500-1000 J/kg is in place across this region as some cloud breaks have allowed for modest diurnal heating. Strong shear remains over this region, which may support isolated strong/gusty downdraft winds. An isolated/marginal severe risk may also exist from the St. Louis metro area northeastward into central IL through the rest of the afternoon, as a small increase in instability in the presence of strong shear has occurred on the eastern edge of the broad precipitation shield over MO. ..Gleason.. 09/22/2019 .PREV DISCUSSION... /ISSUED 1117 AM CDT Sun Sep 22 2019/ ...OK to IL... No changes have been made to the ongoing forecast. A band of relatively fast winds aloft extends from the southern and central Plains into the mid MS valley and Great Lakes region today. A strong shortwave trough embedded in this flow over western KS/OK will track into MO/IL during this forecast period. Considerable cloud cover and areas of precipitation will continue to affect the MRGL risk corridor this afternoon. Despite the weak instability and poor lapse rates, forecast soundings show sufficient vertical shear to pose a limited risk of a storm or two becoming intense with damaging wind potential and some tornado risk. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Sun Sep 22 2019 Valid 222000Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS EXTENDING FROM PARTS OF OKLAHOMA NORTHEASTWARD TO INDIANA... ...SUMMARY... Isolated damaging winds, and perhaps a tornado or two, will remain possible through this evening from parts of Oklahoma to Indiana. ...20Z Update... No changes have been made to the Marginal Risk extending from central OK northeastward to IL and far northwestern IN. A broad area of persistent rain showers across parts of MO into IL has hampered diurnal heating and the development of instability across this area. Relatively better, but still limited, severe potential may exist in a narrow corridor from parts of northern/central OK into southeastern KS and far western MO ahead of a surface cold front. MLCAPE around 500-1000 J/kg is in place across this region as some cloud breaks have allowed for modest diurnal heating. Strong shear remains over this region, which may support isolated strong/gusty downdraft winds. An isolated/marginal severe risk may also exist from the St. Louis metro area northeastward into central IL through the rest of the afternoon, as a small increase in instability in the presence of strong shear has occurred on the eastern edge of the broad precipitation shield over MO. ..Gleason.. 09/22/2019 .PREV DISCUSSION... /ISSUED 1117 AM CDT Sun Sep 22 2019/ ...OK to IL... No changes have been made to the ongoing forecast. A band of relatively fast winds aloft extends from the southern and central Plains into the mid MS valley and Great Lakes region today. A strong shortwave trough embedded in this flow over western KS/OK will track into MO/IL during this forecast period. Considerable cloud cover and areas of precipitation will continue to affect the MRGL risk corridor this afternoon. Despite the weak instability and poor lapse rates, forecast soundings show sufficient vertical shear to pose a limited risk of a storm or two becoming intense with damaging wind potential and some tornado risk. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Sun Sep 22 2019 Valid 222000Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS EXTENDING FROM PARTS OF OKLAHOMA NORTHEASTWARD TO INDIANA... ...SUMMARY... Isolated damaging winds, and perhaps a tornado or two, will remain possible through this evening from parts of Oklahoma to Indiana. ...20Z Update... No changes have been made to the Marginal Risk extending from central OK northeastward to IL and far northwestern IN. A broad area of persistent rain showers across parts of MO into IL has hampered diurnal heating and the development of instability across this area. Relatively better, but still limited, severe potential may exist in a narrow corridor from parts of northern/central OK into southeastern KS and far western MO ahead of a surface cold front. MLCAPE around 500-1000 J/kg is in place across this region as some cloud breaks have allowed for modest diurnal heating. Strong shear remains over this region, which may support isolated strong/gusty downdraft winds. An isolated/marginal severe risk may also exist from the St. Louis metro area northeastward into central IL through the rest of the afternoon, as a small increase in instability in the presence of strong shear has occurred on the eastern edge of the broad precipitation shield over MO. ..Gleason.. 09/22/2019 .PREV DISCUSSION... /ISSUED 1117 AM CDT Sun Sep 22 2019/ ...OK to IL... No changes have been made to the ongoing forecast. A band of relatively fast winds aloft extends from the southern and central Plains into the mid MS valley and Great Lakes region today. A strong shortwave trough embedded in this flow over western KS/OK will track into MO/IL during this forecast period. Considerable cloud cover and areas of precipitation will continue to affect the MRGL risk corridor this afternoon. Despite the weak instability and poor lapse rates, forecast soundings show sufficient vertical shear to pose a limited risk of a storm or two becoming intense with damaging wind potential and some tornado risk. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Sun Sep 22 2019 Valid 231200Z - 241200Z Consensus among guidance exists that the LAX/TPH pressure gradient will increase late Monday into early Tuesday morning. Accordingly, high resolution guidance has forecast 15-25 mph winds in the higher terrain of Los Angeles/Ventura counties. There is still uncertainty with regard to how low overnight RH will drop in these areas as well as how long these conditions will occur. Nonetheless, trends in guidance suggest an increase in fire weather concerns for these areas and elevated highlights have been introduced for that reason. ..Wendt.. 09/22/2019 .PREV DISCUSSION... /ISSUED 0130 AM CDT Sun Sep 22 2019/ ...Synopsis... A strong mid/upper-level trough -- and associated area of enhanced mid-level flow -- is forecast to gradually move southeastward from the Great Basin to the Desert Southwest Day 2/Monday. ...Northern California... Elevated to locally critical fire weather conditions are expected Day 2/Monday across portions of the Sacramento Valley (especially western portions of the valley) and adjacent North Coast Ranges, as dry/gusty low-level northerly flow -- beneath the aforementioned area of enhanced mid-level flow -- overlaps near critical minimum RH values and at least marginally receptive fuels. Elevated fire weather conditions may also persist into the overnight due to poor RH recoveries and lingering gusty/breezy surface winds -- especially in terrain favored areas of the North Coast Ranges. ...Southern California... While a combination of increasing offshore surface flow and poor overnight RH recoveries may promote at least locally elevated fire weather conditions late overnight Day 2/Monday, the uncertainty regarding timing/coverage of any fire weather conditions precludes a fire weather area at this time. ...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 0259 PM CDT Sun Sep 22 2019 Valid 231200Z - 241200Z Consensus among guidance exists that the LAX/TPH pressure gradient will increase late Monday into early Tuesday morning. Accordingly, high resolution guidance has forecast 15-25 mph winds in the higher terrain of Los Angeles/Ventura counties. There is still uncertainty with regard to how low overnight RH will drop in these areas as well as how long these conditions will occur. Nonetheless, trends in guidance suggest an increase in fire weather concerns for these areas and elevated highlights have been introduced for that reason. ..Wendt.. 09/22/2019 .PREV DISCUSSION... /ISSUED 0130 AM CDT Sun Sep 22 2019/ ...Synopsis... A strong mid/upper-level trough -- and associated area of enhanced mid-level flow -- is forecast to gradually move southeastward from the Great Basin to the Desert Southwest Day 2/Monday. ...Northern California... Elevated to locally critical fire weather conditions are expected Day 2/Monday across portions of the Sacramento Valley (especially western portions of the valley) and adjacent North Coast Ranges, as dry/gusty low-level northerly flow -- beneath the aforementioned area of enhanced mid-level flow -- overlaps near critical minimum RH values and at least marginally receptive fuels. Elevated fire weather conditions may also persist into the overnight due to poor RH recoveries and lingering gusty/breezy surface winds -- especially in terrain favored areas of the North Coast Ranges. ...Southern California... While a combination of increasing offshore surface flow and poor overnight RH recoveries may promote at least locally elevated fire weather conditions late overnight Day 2/Monday, the uncertainty regarding timing/coverage of any fire weather conditions precludes a fire weather area at this time. ...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 0259 PM CDT Sun Sep 22 2019 Valid 231200Z - 241200Z Consensus among guidance exists that the LAX/TPH pressure gradient will increase late Monday into early Tuesday morning. Accordingly, high resolution guidance has forecast 15-25 mph winds in the higher terrain of Los Angeles/Ventura counties. There is still uncertainty with regard to how low overnight RH will drop in these areas as well as how long these conditions will occur. Nonetheless, trends in guidance suggest an increase in fire weather concerns for these areas and elevated highlights have been introduced for that reason. ..Wendt.. 09/22/2019 .PREV DISCUSSION... /ISSUED 0130 AM CDT Sun Sep 22 2019/ ...Synopsis... A strong mid/upper-level trough -- and associated area of enhanced mid-level flow -- is forecast to gradually move southeastward from the Great Basin to the Desert Southwest Day 2/Monday. ...Northern California... Elevated to locally critical fire weather conditions are expected Day 2/Monday across portions of the Sacramento Valley (especially western portions of the valley) and adjacent North Coast Ranges, as dry/gusty low-level northerly flow -- beneath the aforementioned area of enhanced mid-level flow -- overlaps near critical minimum RH values and at least marginally receptive fuels. Elevated fire weather conditions may also persist into the overnight due to poor RH recoveries and lingering gusty/breezy surface winds -- especially in terrain favored areas of the North Coast Ranges. ...Southern California... While a combination of increasing offshore surface flow and poor overnight RH recoveries may promote at least locally elevated fire weather conditions late overnight Day 2/Monday, the uncertainty regarding timing/coverage of any fire weather conditions precludes a fire weather area at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1228 PM CDT Sun Sep 22 2019 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTHERN/CENTRAL ARIZONA... ...SUMMARY... Scattered storms, some of which may be severe with damaging winds and large hail, appear possible over much of Arizona on Monday. ...Arizona into Southwestern New Mexico... Embedded within large-scale upper troughing over much of the western CONUS, an upper trough/low will develop southward across the western Great Basin into the Southwest through the period. In advance of this feature, low-level moisture is forecast to rapidly increase along the CA/AZ border eastward into southern/central AZ by early Monday morning. There are some indications that isolated showers/storms may be ongoing at the start of the period Monday morning across mainly southern AZ. The effect that this possible early convection may have on destabilization and severe storm potential later in the day remains unclear. Regardless, strengthening west-southwesterly winds at mid levels in combination with increasing instability suggest that at least isolated severe storms will be possible across much of southern/central AZ Monday afternoon and evening. MLCAPE should reach to around 1000-1500 J/kg from the Mogollon Rim southward, with locally higher values possible in far western AZ. 35-50 kt of effective bulk shear will support supercells, with initial convective development probably occurring along or just east of the CA/AZ border. Isolated large hail will be possible with these mainly discrete storms, as generally straight hodographs become elongated at mid/upper levels. As storms spread eastward through the afternoon, some clustering may occur as low-level lapse rates steepen through diurnal heating and mixing of the boundary layer. Damaging winds may become an increasing concern with eastward extent across southern/central AZ into Monday evening if this upscale growth occurs. An isolated severe threat may persist Monday night into parts of southwestern NM before instability eventually wanes. Across northern AZ, both low-level moisture and related instability are forecast to be weaker, with a more isolated/marginal hail/wind threat. ...Northeast... An upper trough/low will move quickly eastward from the Great Lakes across the Northeast, OH Valley, and Mid-Atlantic on Monday. Strong mid/upper-level winds will be present across these regions in association with the upper trough/low. At the surface, a cold front will likewise sweep eastward across these regions through the day. Mid-level lapse rates over these areas are expected to remain quite meager, and widespread cloudiness will likely be present. But, surface dewpoints generally in the low to mid 60s ahead of the front and modest diurnal heating will probably support weak instability by Monday afternoon along/ahead of the front. MLCAPE should generally remain at or below 500 J/kg. This meager instability will probably temper the overall severe threat, even though strong shear will be present owing to the strengthening wind field through mid/upper levels. While some strong/gusty downdraft winds cannot be completely ruled out with rain showers or any low-topped storms that develop, the lack of stronger forecast instability precludes introduction of 5% severe probabilities for wind at this time. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 15% - Slight Hail: 15% - Slight ..Gleason.. 09/22/2019 Read more