Severe Storms

WW 0653 Status Updates
STATUS REPORT ON WW 653 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 40 N PHX TO 25 ENE PHX TO 35 SE GBN. ..SPC..09/15/19 ATTN...WFO...PSR... STATUS REPORT FOR WS 653 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS AZC013-150240- AZ . ARIZONA COUNTIES INCLUDED ARE MARICOPA THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 653 SEVERE TSTM AZ 142145Z - 150500Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 653 NWS Storm Prediction Center Norman OK 345 PM MDT Sat Sep 14 2019 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Southern Arizona * Effective this Saturday afternoon and evening from 345 PM until 1100 PM MDT. * Primary threats include... Isolated significant damaging wind gusts to 75 mph possible SUMMARY...Thunderstorms will continue to increase over the mountains, with some of the storms and their related outflows expected to move onto the desert floor this evening. Severe-caliber winds/blowing dust will be possible. The severe thunderstorm watch area is approximately along and 50 statute miles north and south of a line from 55 miles west northwest of Gila Bend AZ to 90 miles east of Phoenix AZ. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU3). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && AVIATION...A few severe thunderstorms with hail surface and aloft to 1 inch. Extreme turbulence and surface wind gusts to 65 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 07015. ...Guyer Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0748 PM CDT Sat Sep 14 2019 Valid 150100Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF CENTRAL AND SOUTHERN AZ... ...SUMMARY... Isolated to scattered severe wind gusts are possible the remainder of the evening across southern and central Arizona. Isolated severe storms with large hail and damaging wind gusts are possible from the Upper Midwest to the central Great Plains through tonight. ...01z Update... The Marginal risk area has been removed from the Appalachians as convection has diminished with loss of daytime heating. A few storms will linger another 1-2 hours, but severe threat is expected to be low the remainder of the evening. The Marginal risk area across the Upper Midwest has been modified based on latest hi-res guidance trends and surface observations. The biggest change was to trim some of the area across central MN into northern WI. Thunderstorms from earlier this afternoon have largely weakened, and additional convection forming that far north overnight does not appear likely. Latest hi-res guidance has trended toward additional development later this evening/overnight ahead of a weak surface boundary/low as the low level jet increases and stronger warm advection shifts east from southern WI into northern IL. Expect that a line/cluster of storms will develop western/central IL and shift east into southern WI/northern IL, posing mainly a threat for marginal hail and possibly some strong gusts. Given latest trends, have expanded the Marginal risk on the southern end across southern IA/northern IL. Thunderstorms continue to shift westward off of higher terrain across central AZ. Strong gusts will continue to be possible with this activity for several more hours this evening. The severe threat should diminish after 06z as convection approaches the Lower CO Valley. ..Leitman.. 09/15/2019 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0748 PM CDT Sat Sep 14 2019 Valid 150100Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF CENTRAL AND SOUTHERN AZ... ...SUMMARY... Isolated to scattered severe wind gusts are possible the remainder of the evening across southern and central Arizona. Isolated severe storms with large hail and damaging wind gusts are possible from the Upper Midwest to the central Great Plains through tonight. ...01z Update... The Marginal risk area has been removed from the Appalachians as convection has diminished with loss of daytime heating. A few storms will linger another 1-2 hours, but severe threat is expected to be low the remainder of the evening. The Marginal risk area across the Upper Midwest has been modified based on latest hi-res guidance trends and surface observations. The biggest change was to trim some of the area across central MN into northern WI. Thunderstorms from earlier this afternoon have largely weakened, and additional convection forming that far north overnight does not appear likely. Latest hi-res guidance has trended toward additional development later this evening/overnight ahead of a weak surface boundary/low as the low level jet increases and stronger warm advection shifts east from southern WI into northern IL. Expect that a line/cluster of storms will develop western/central IL and shift east into southern WI/northern IL, posing mainly a threat for marginal hail and possibly some strong gusts. Given latest trends, have expanded the Marginal risk on the southern end across southern IA/northern IL. Thunderstorms continue to shift westward off of higher terrain across central AZ. Strong gusts will continue to be possible with this activity for several more hours this evening. The severe threat should diminish after 06z as convection approaches the Lower CO Valley. ..Leitman.. 09/15/2019 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0748 PM CDT Sat Sep 14 2019 Valid 150100Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF CENTRAL AND SOUTHERN AZ... ...SUMMARY... Isolated to scattered severe wind gusts are possible the remainder of the evening across southern and central Arizona. Isolated severe storms with large hail and damaging wind gusts are possible from the Upper Midwest to the central Great Plains through tonight. ...01z Update... The Marginal risk area has been removed from the Appalachians as convection has diminished with loss of daytime heating. A few storms will linger another 1-2 hours, but severe threat is expected to be low the remainder of the evening. The Marginal risk area across the Upper Midwest has been modified based on latest hi-res guidance trends and surface observations. The biggest change was to trim some of the area across central MN into northern WI. Thunderstorms from earlier this afternoon have largely weakened, and additional convection forming that far north overnight does not appear likely. Latest hi-res guidance has trended toward additional development later this evening/overnight ahead of a weak surface boundary/low as the low level jet increases and stronger warm advection shifts east from southern WI into northern IL. Expect that a line/cluster of storms will develop western/central IL and shift east into southern WI/northern IL, posing mainly a threat for marginal hail and possibly some strong gusts. Given latest trends, have expanded the Marginal risk on the southern end across southern IA/northern IL. Thunderstorms continue to shift westward off of higher terrain across central AZ. Strong gusts will continue to be possible with this activity for several more hours this evening. The severe threat should diminish after 06z as convection approaches the Lower CO Valley. ..Leitman.. 09/15/2019 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0748 PM CDT Sat Sep 14 2019 Valid 150100Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF CENTRAL AND SOUTHERN AZ... ...SUMMARY... Isolated to scattered severe wind gusts are possible the remainder of the evening across southern and central Arizona. Isolated severe storms with large hail and damaging wind gusts are possible from the Upper Midwest to the central Great Plains through tonight. ...01z Update... The Marginal risk area has been removed from the Appalachians as convection has diminished with loss of daytime heating. A few storms will linger another 1-2 hours, but severe threat is expected to be low the remainder of the evening. The Marginal risk area across the Upper Midwest has been modified based on latest hi-res guidance trends and surface observations. The biggest change was to trim some of the area across central MN into northern WI. Thunderstorms from earlier this afternoon have largely weakened, and additional convection forming that far north overnight does not appear likely. Latest hi-res guidance has trended toward additional development later this evening/overnight ahead of a weak surface boundary/low as the low level jet increases and stronger warm advection shifts east from southern WI into northern IL. Expect that a line/cluster of storms will develop western/central IL and shift east into southern WI/northern IL, posing mainly a threat for marginal hail and possibly some strong gusts. Given latest trends, have expanded the Marginal risk on the southern end across southern IA/northern IL. Thunderstorms continue to shift westward off of higher terrain across central AZ. Strong gusts will continue to be possible with this activity for several more hours this evening. The severe threat should diminish after 06z as convection approaches the Lower CO Valley. ..Leitman.. 09/15/2019 Read more

WW 0653 Status Updates
STATUS REPORT ON WW 653 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 60 NE PHX TO 50 E PHX TO 45 NNW TUS. ..SPC..09/15/19 ATTN...WFO...PSR... STATUS REPORT FOR WS 653 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS AZC013-021-150140- AZ . ARIZONA COUNTIES INCLUDED ARE MARICOPA PINAL THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 0653 Status Updates
STATUS REPORT ON WW 653 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 65 NE PHX TO 65 E PHX TO 40 NNE TUS. ..SPC..09/14/19 ATTN...WFO...PSR... STATUS REPORT FOR WS 653 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS AZC007-013-021-150040- AZ . ARIZONA COUNTIES INCLUDED ARE GILA MARICOPA PINAL THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

MD 1977 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR WESTERN INTO NORTH-CENTRAL KS...SOUTHEAST NE
Mesoscale Discussion 1977 NWS Storm Prediction Center Norman OK 0615 PM CDT Sat Sep 14 2019 Areas affected...Western into north-central KS...Southeast NE Concerning...Severe potential...Watch unlikely Valid 142315Z - 150115Z Probability of Watch Issuance...20 percent SUMMARY...While extent of storm development remains uncertain, isolated strong thunderstorms are possible this evening with a conditional risk of locally severe wind gusts and hail. Watch issuance is currently not anticipated. DISCUSSION...Cumulus has been gradually increasing along a weak surface boundary from western KS northeastward into south-central NE. Strong heating and sufficient low-level moisture have allowed MLCAPE values to rise into the 2000-3500 J/kg range across this region, per recent mesoanalyses. This area is on the southern fringe of stronger midlevel flow, with effective shear ranging from 20-25 kt across western KS to around 30 kt into southeast NE. This environment would conditionally support organized multicells, or even potentially a supercell or two where shear is slightly stronger into north-central KS/southeast NE. Large-scale ascent is weak at best across this area, and the extent of storm development (if any) remains uncertain at this time. If deep convection can be sustained, locally severe wind gusts and some hail will be possible. Given uncertainty regarding storm coverage, and the likelihood that any severe threat would only last until around 01-02Z before MLCINH increases, watch issuance is unlikely. ..Dean/Guyer.. 09/14/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...OAX...TOP...ICT...GID...DDC... LAT...LON 38769988 39869886 40769804 41039762 41239685 41319641 40899609 40019648 39319726 38779814 38549869 38289969 38220023 38320043 38769988 Read more

MD 1978 CONCERNING SEVERE THUNDERSTORM WATCH 653... FOR AZ
Mesoscale Discussion 1978 NWS Storm Prediction Center Norman OK 0653 PM CDT Sat Sep 14 2019 Areas affected...AZ Concerning...Severe Thunderstorm Watch 653... Valid 142353Z - 150200Z The severe weather threat for Severe Thunderstorm Watch 653 continues. SUMMARY...Gusty winds remain possible with thunderstorms this evening. DISCUSSION...Scattered thunderstorms are slowly organizing along the higher terrain of Gila/Yavapai Counties. This activity is beginning to surge a bit as it propagates southwest at roughly 20kt toward lower desert regions. While deep-layer shear does not favor fast-moving storms, low sub-cloud layer RH will prove conducive for gusty downdrafts where temp/dew point spreads are on the order of 45-50F. Unless/until a more substantial cold pool can evolve, severe wind gusts should remain more isolated in nature. Deep convection is expected to gradually spread across the remainder of ww653 over the next few hours. ..Darrow.. 09/14/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...TWC...FGZ...PSR... LAT...LON 32431238 33941311 34561222 33841136 32641121 32431238 Read more

No Mesoscale Discussions are in effect as of Sat Sep 14 22:19:08 UTC 2019.

WW 0653 Status Updates
STATUS FOR WATCH 0653 HAS NOT BEEN ISSUED YET Read more

WW 653 SEVERE TSTM AZ 142145Z - 150500Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 653 NWS Storm Prediction Center Norman OK 345 PM MDT Sat Sep 14 2019 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Southern Arizona * Effective this Saturday afternoon and evening from 345 PM until 1100 PM MDT. * Primary threats include... Isolated significant damaging wind gusts to 75 mph possible SUMMARY...Thunderstorms will continue to increase over the mountains, with some of the storms and their related outflows expected to move onto the desert floor this evening. Severe-caliber winds/blowing dust will be possible. The severe thunderstorm watch area is approximately along and 50 statute miles north and south of a line from 55 miles west northwest of Gila Bend AZ to 90 miles east of Phoenix AZ. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU3). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && AVIATION...A few severe thunderstorms with hail surface and aloft to 1 inch. Extreme turbulence and surface wind gusts to 65 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 07015. ...Guyer Read more

No watches are valid as of Sat Sep 14 20:53:01 UTC 2019.

MD 1976 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR CENTRAL/SOUTHERN AZ
Mesoscale Discussion 1976 NWS Storm Prediction Center Norman OK 0321 PM CDT Sat Sep 14 2019 Areas affected...Central/Southern AZ Concerning...Severe potential...Watch possible Valid 142021Z - 142215Z Probability of Watch Issuance...60 percent SUMMARY...Increasing thunderstorm coverage is anticipated across southern/central AZ over the next several hours. Strong wind gusts are possible and trends will be monitored for possible watch issuance. DISCUSSION...Moisture continues to advect northward/northeastward into southern/central AZ as an MCV currently near the far southeast NM/Mexico border slowly moves north. Dewpoints across much of the region have remained steady or slightly increased, evidence of low-level moisture advection amidst strong daytime heating across central AZ. At least modest convective inhibition remains in place across much of the region, but continued heating and moisture advection is expected erode this inhibition while also increasing buoyancy. As a result of the decreasing convective inhibition, increasing buoyancy, and lift resulting from the approaching MCV (as well as orographic effects), thunderstorm coverage is expected to gradually increase over the next hour or two. In addition to this increasing thunderstorm coverage, enhanced easterly flow around the eastern/northeastern periphery of the MCV is expected to spread into more of central AZ. Recent EMX VAD has sampled this increased easterly flow well. Consequently, storms will likely move off the higher terrain and into the Lower Desert with an attendant risk for strong wind gusts. Convective trends are being monitored for potential watch issuance. ..Mosier/Guyer.. 09/14/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...TWC...FGZ...PSR... LAT...LON 31641036 31621124 31951237 32501296 33641300 34241279 34561237 34601171 34361109 33951077 33401040 32701012 32021006 31641036 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0239 PM CDT Sat Sep 14 2019 Valid 142000Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF SOUTHERN ARIZONA... ...SUMMARY... Isolated to scattered severe wind gusts are possible this afternoon and evening across southern and central Arizona. Isolated severe storms with large hail and damaging wind gusts are possible from the Upper Midwest to the central Great Plains through tonight. ...Discussion... Only minor adjustments have been made to the previous forecast. ..Dial.. 09/14/2019 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Sep 14 2019/ ...Southern/central AZ... An MCV over western Chihuahua will drift north-northwestward across southeast AZ through tonight. 50s surface dew points are common across southern AZ amid easterly flow north of this MCV. In conjunction with ample heating northwest of the thicker cloud cover near the MCV, a modestly buoyant air mass with MLCAPE approaching 1000 J/kg should develop by peak heating. 15-25 kt east-northeast 700-500 mb winds around the north side of the MCV will be favorable for cells and semi-organized clusters to spread off the Mogollon Rim into the lower deserts with a threat for severe gusts. Whether more organized clustering can evolve is uncertain compared to the significant severe wind event two weeks ago, but there is at least sufficient damaging wind potential to warrant a Slight Risk across parts of the Gila Valley. ...Upper Midwest to the central Great Plains... Elevated thunderstorms are ongoing in western IA on the leading edge of a low-level warm theta-e advection plume. This plume and attendant zone of ascent will spread east-northeast across the Upper MS Valley into tonight in advance of a low-amplitude shortwave trough near the ND/MB border that will move east-southeast into Lake Superior. This elevated convection will pose a threat for isolated large hail, mainly this evening into tonight with a probable decay cycle this afternoon. A risk for locally damaging winds may also develop tonight towards the IA/IL/WI border region if a cluster can become semi-organized. In the wake of the warm advection regime, storm initiation will depend on weak low-level ascent along a surface trough that extends southwestward across NE/KS. Stronger surface heating and deeper mixing is expected along the trough in KS, with lesser mixing depths and a greater probability of maintaining MLCIN through the afternoon in the warm sector farther northeast. Thus, surface-based thunderstorm development should be sparse and may struggle to be sustained during the late afternoon/early evening. If surface-based storms can form as far northeast as southern MN this afternoon, vertical shear profiles will be sufficient for supercells. Weaker vertical shear is expected with southwestward extent into southwest KS, where high-based storms would pose a threat for isolated severe wind and hail. ...Central Appalachians... A narrow corridor of weak to modest buoyancy is expected with scattered storms along a cold front and over the higher terrain through early evening. Isolated strong downburst winds are possible on the periphery of weak to moderate mid-level southwesterlies. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0239 PM CDT Sat Sep 14 2019 Valid 142000Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF SOUTHERN ARIZONA... ...SUMMARY... Isolated to scattered severe wind gusts are possible this afternoon and evening across southern and central Arizona. Isolated severe storms with large hail and damaging wind gusts are possible from the Upper Midwest to the central Great Plains through tonight. ...Discussion... Only minor adjustments have been made to the previous forecast. ..Dial.. 09/14/2019 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Sep 14 2019/ ...Southern/central AZ... An MCV over western Chihuahua will drift north-northwestward across southeast AZ through tonight. 50s surface dew points are common across southern AZ amid easterly flow north of this MCV. In conjunction with ample heating northwest of the thicker cloud cover near the MCV, a modestly buoyant air mass with MLCAPE approaching 1000 J/kg should develop by peak heating. 15-25 kt east-northeast 700-500 mb winds around the north side of the MCV will be favorable for cells and semi-organized clusters to spread off the Mogollon Rim into the lower deserts with a threat for severe gusts. Whether more organized clustering can evolve is uncertain compared to the significant severe wind event two weeks ago, but there is at least sufficient damaging wind potential to warrant a Slight Risk across parts of the Gila Valley. ...Upper Midwest to the central Great Plains... Elevated thunderstorms are ongoing in western IA on the leading edge of a low-level warm theta-e advection plume. This plume and attendant zone of ascent will spread east-northeast across the Upper MS Valley into tonight in advance of a low-amplitude shortwave trough near the ND/MB border that will move east-southeast into Lake Superior. This elevated convection will pose a threat for isolated large hail, mainly this evening into tonight with a probable decay cycle this afternoon. A risk for locally damaging winds may also develop tonight towards the IA/IL/WI border region if a cluster can become semi-organized. In the wake of the warm advection regime, storm initiation will depend on weak low-level ascent along a surface trough that extends southwestward across NE/KS. Stronger surface heating and deeper mixing is expected along the trough in KS, with lesser mixing depths and a greater probability of maintaining MLCIN through the afternoon in the warm sector farther northeast. Thus, surface-based thunderstorm development should be sparse and may struggle to be sustained during the late afternoon/early evening. If surface-based storms can form as far northeast as southern MN this afternoon, vertical shear profiles will be sufficient for supercells. Weaker vertical shear is expected with southwestward extent into southwest KS, where high-based storms would pose a threat for isolated severe wind and hail. ...Central Appalachians... A narrow corridor of weak to modest buoyancy is expected with scattered storms along a cold front and over the higher terrain through early evening. Isolated strong downburst winds are possible on the periphery of weak to moderate mid-level southwesterlies. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0239 PM CDT Sat Sep 14 2019 Valid 142000Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF SOUTHERN ARIZONA... ...SUMMARY... Isolated to scattered severe wind gusts are possible this afternoon and evening across southern and central Arizona. Isolated severe storms with large hail and damaging wind gusts are possible from the Upper Midwest to the central Great Plains through tonight. ...Discussion... Only minor adjustments have been made to the previous forecast. ..Dial.. 09/14/2019 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Sep 14 2019/ ...Southern/central AZ... An MCV over western Chihuahua will drift north-northwestward across southeast AZ through tonight. 50s surface dew points are common across southern AZ amid easterly flow north of this MCV. In conjunction with ample heating northwest of the thicker cloud cover near the MCV, a modestly buoyant air mass with MLCAPE approaching 1000 J/kg should develop by peak heating. 15-25 kt east-northeast 700-500 mb winds around the north side of the MCV will be favorable for cells and semi-organized clusters to spread off the Mogollon Rim into the lower deserts with a threat for severe gusts. Whether more organized clustering can evolve is uncertain compared to the significant severe wind event two weeks ago, but there is at least sufficient damaging wind potential to warrant a Slight Risk across parts of the Gila Valley. ...Upper Midwest to the central Great Plains... Elevated thunderstorms are ongoing in western IA on the leading edge of a low-level warm theta-e advection plume. This plume and attendant zone of ascent will spread east-northeast across the Upper MS Valley into tonight in advance of a low-amplitude shortwave trough near the ND/MB border that will move east-southeast into Lake Superior. This elevated convection will pose a threat for isolated large hail, mainly this evening into tonight with a probable decay cycle this afternoon. A risk for locally damaging winds may also develop tonight towards the IA/IL/WI border region if a cluster can become semi-organized. In the wake of the warm advection regime, storm initiation will depend on weak low-level ascent along a surface trough that extends southwestward across NE/KS. Stronger surface heating and deeper mixing is expected along the trough in KS, with lesser mixing depths and a greater probability of maintaining MLCIN through the afternoon in the warm sector farther northeast. Thus, surface-based thunderstorm development should be sparse and may struggle to be sustained during the late afternoon/early evening. If surface-based storms can form as far northeast as southern MN this afternoon, vertical shear profiles will be sufficient for supercells. Weaker vertical shear is expected with southwestward extent into southwest KS, where high-based storms would pose a threat for isolated severe wind and hail. ...Central Appalachians... A narrow corridor of weak to modest buoyancy is expected with scattered storms along a cold front and over the higher terrain through early evening. Isolated strong downburst winds are possible on the periphery of weak to moderate mid-level southwesterlies. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0239 PM CDT Sat Sep 14 2019 Valid 142000Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF SOUTHERN ARIZONA... ...SUMMARY... Isolated to scattered severe wind gusts are possible this afternoon and evening across southern and central Arizona. Isolated severe storms with large hail and damaging wind gusts are possible from the Upper Midwest to the central Great Plains through tonight. ...Discussion... Only minor adjustments have been made to the previous forecast. ..Dial.. 09/14/2019 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Sep 14 2019/ ...Southern/central AZ... An MCV over western Chihuahua will drift north-northwestward across southeast AZ through tonight. 50s surface dew points are common across southern AZ amid easterly flow north of this MCV. In conjunction with ample heating northwest of the thicker cloud cover near the MCV, a modestly buoyant air mass with MLCAPE approaching 1000 J/kg should develop by peak heating. 15-25 kt east-northeast 700-500 mb winds around the north side of the MCV will be favorable for cells and semi-organized clusters to spread off the Mogollon Rim into the lower deserts with a threat for severe gusts. Whether more organized clustering can evolve is uncertain compared to the significant severe wind event two weeks ago, but there is at least sufficient damaging wind potential to warrant a Slight Risk across parts of the Gila Valley. ...Upper Midwest to the central Great Plains... Elevated thunderstorms are ongoing in western IA on the leading edge of a low-level warm theta-e advection plume. This plume and attendant zone of ascent will spread east-northeast across the Upper MS Valley into tonight in advance of a low-amplitude shortwave trough near the ND/MB border that will move east-southeast into Lake Superior. This elevated convection will pose a threat for isolated large hail, mainly this evening into tonight with a probable decay cycle this afternoon. A risk for locally damaging winds may also develop tonight towards the IA/IL/WI border region if a cluster can become semi-organized. In the wake of the warm advection regime, storm initiation will depend on weak low-level ascent along a surface trough that extends southwestward across NE/KS. Stronger surface heating and deeper mixing is expected along the trough in KS, with lesser mixing depths and a greater probability of maintaining MLCIN through the afternoon in the warm sector farther northeast. Thus, surface-based thunderstorm development should be sparse and may struggle to be sustained during the late afternoon/early evening. If surface-based storms can form as far northeast as southern MN this afternoon, vertical shear profiles will be sufficient for supercells. Weaker vertical shear is expected with southwestward extent into southwest KS, where high-based storms would pose a threat for isolated severe wind and hail. ...Central Appalachians... A narrow corridor of weak to modest buoyancy is expected with scattered storms along a cold front and over the higher terrain through early evening. Isolated strong downburst winds are possible on the periphery of weak to moderate mid-level southwesterlies. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0155 PM CDT Sat Sep 14 2019 Valid 151200Z - 161200Z ...CRITICAL FIRE WEATHER AREA FOR NORTHWEST NV...NORTHEAST CA...SOUTHEAST OR...SOUTHWEST ID... ...CRITICAL FIRE WEATHER AREA FOR CENTRAL/EASTERN NV... Minor modifications were made to the outlook based on latest high-resolution guidance and observations. Wind gusts of 50+ mph may occur across portions of northwest Nevada tomorrow with locally extremely critical conditions still possible. Otherwise, the forecast remains on track, and please see the discussion below for more details. ..Nauslar.. 09/14/2019 .PREV DISCUSSION... /ISSUED 0100 AM CDT Sat Sep 14 2019/ ...Synopsis... A vigorous upper trough is forecast to amplify and shift eastward across the Pacific Coast into the Great Basin/interior Northwest by Monday morning. At the surface, low pressure will deepen from the northern Great Basin into portions of the northern High Plains, with a surface trough extending southward into the central/southern High Plains. ...Great Basin and vicinity... As low/midlevel flow increases in advance of the strong upper trough, a broad area of elevated to potentially critical fire weather conditions is forecast to develop from the Great Basin and vicinity eastward into portions of southern WY. Within this region, critical conditions are likely over northwest NV and adjacent portions of northeast CA, southeast OR, and far southwest ID. In this area, sustained winds of 20-30 mph will combine with minimum RH values of 8-15%, with localized areas of extremely critical conditions possible. Another region of potentially critical conditions is forecast over portions of central/eastern NV, where sustained winds of 15-25 mph are forecast in conjunction with minimum RH values of 10-15%. The onset of critical conditions in these areas may occur as early as late morning, with critical conditions potentially persisting into late Sunday night across the westernmost critical area. ...Please see www.spc.noaa.gov/fire for graphic product... Read more