Severe Storms

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1235 AM CDT Sat Aug 31 2019 Valid 311200Z - 011200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected across the continental U.S. today. ...DISCUSSION... An upper-level trough will move across the Mississippi Valley today as an upper-level ridge moves slowly eastward across the northern Rockies and Four Corners region. At the surface, a post-frontal airmass will be in place across much of the central and eastern U.S. Thunderstorm development may take place across parts of the mid Mississippi and Ohio Valleys southwestward into parts of the southern Plains. Instability and deep-layer shear are forecast to be too weak for a severe threat across these areas today through tonight. ..Broyles/Squitieri.. 08/31/2019 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0743 PM CDT Fri Aug 30 2019 Valid 310100Z - 311200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE HIGH PLAINS AND MID MISSISSIPPI VALLEY... ...SUMMARY... Marginally severe thunderstorms with hail and strong wind gusts will be possible this evening across parts of the High Plains. A few storms with strong wind gusts will also be possible in the mid Mississippi Valley. ...High Plains... The latest water vapor imagery shows a west to northwest mid-level flow pattern over the central U.S. with a subtle shortwave trough moving through the central High Plains. Thunderstorms have developed just ahead of the trough along a corridor of moderate instability from the western Texas Panhandle into eastern Colorado and western Nebraska. MLCAPE values across this area estimated by the RAP to be in the 1000 to 2000 J/kg range. This combined with 0-6 km shear of 40 to 50 kt, evident on regional WSR-88D VWPs and steep low to mid-level lapse rates should be enough for a marginal severe threat this evening. The stronger storms could produce hail and isolated wind gusts approaching severe limits. ...Mid Mississippi Valley... The latest water vapor imagery shows an upper-level trough over the Ozarks. Ahead of the trough, a cold front is located from southern Missouri into southern Illinois. Thunderstorms have developed along the front on the northwestern edge of a moist airmass with surface dewpoints from the mid 60s to lower 70s F. This is contributing to a corridor of moderate instability across southern Illinois into southern Indiana. As the MCV associated with the convective complex moves eastward, a marginal severe threat will likely continue along this corridor of instability. A few strong wind gusts are expected to be the primary hazard. ..Broyles.. 08/31/2019 Read more

WW 0629 Status Updates
STATUS REPORT ON WW 629 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 45 WNW POF TO 10 S STL TO 30 ENE ALN. WW 629 WILL BE ALLOWED TO EXPIRE AT 310100Z. ..GLEASON..08/31/19 ATTN...WFO...LSX... STATUS REPORT FOR WS 629 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC005-027-119-133-157-163-189-310100- IL . ILLINOIS COUNTIES INCLUDED ARE BOND CLINTON MADISON MONROE RANDOLPH ST. CLAIR WASHINGTON MOC093-099-123-179-186-187-189-221-510-310100- MO . MISSOURI COUNTIES INCLUDED ARE IRON JEFFERSON MADISON REYNOLDS STE. GENEVIEVE ST. FRANCOIS ST. LOUIS WASHINGTON MISSOURI INDEPENDENT CITIES INCLUDED ARE ST. LOUIS CITY Read more

WW 629 SEVERE TSTM IL MO 302045Z - 310100Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 629 NWS Storm Prediction Center Norman OK 345 PM CDT Fri Aug 30 2019 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Southwest Illinois Eastern Missouri * Effective this Friday afternoon and evening from 345 PM until 800 PM CDT. * Primary threats include... Isolated very large hail events to 2 inches in diameter possible Isolated damaging wind gusts to 70 mph possible A tornado or two possible SUMMARY...Isolated severe storms may further develop and increase in coverage/intensity from east-central/southeast Missouri into southwest Illinois through early evening. Large hail, locally damaging winds and perhaps a tornado will all be possible, particularly along/south of the I-44 corridor. The severe thunderstorm watch area is approximately along and 50 statute miles north and south of a line from 45 miles west northwest of Farmington MO to 35 miles east southeast of Scott Afb IL. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU9). 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 2 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 25020. ...Guyer Read more

MD 1904 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR FAR EASTERN WYOMING INTO EXTREME SOUTHWESTERN SOUTH DAKOTA AND EXTREME WESTERN NEBRASKA
Mesoscale Discussion 1904 NWS Storm Prediction Center Norman OK 0554 PM CDT Fri Aug 30 2019 Areas affected...Far eastern Wyoming into extreme southwestern South Dakota and extreme western Nebraska Concerning...Severe potential...Watch unlikely Valid 302254Z - 310030Z Probability of Watch Issuance...5 percent SUMMARY...Isolated damaging wind gusts and perhaps large hail are possible with the stronger storms developing off of the higher terrain. Given the isolated and brief nature of the severe threat, a WW issuance is not currently anticipated. DISCUSSION...Convection has recently begun to intensify along the higher terrain in far eastern WY with the aid of afternoon peak heating and the approach of a vort max in central WY. Buoyancy across the discussion area is rather modest, with steep mid-level lapse rates of around 8 C/km fostering MLCAPE values mainly between 500-1000 J/kg. Combined with effective bulk shear values between 40-50 knots, organization into multicellular clusters and perhaps brief, transient supercell structures are possible. Organization and acquired mid-level rotation of the more robust storms may pose a threat for a few severe hail stones. Though low-level lapse rates are not particularly steep, a dry sub-cloud layer extending up to 600 mb suggests that adequate evaporative cooling may also transpire to support a few damaging wind gusts with the most intense storms. Nonetheless, the isolated nature of the severe threat precludes a WW issuance. ..Squitieri/Dial.. 08/30/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...UNR...CYS... LAT...LON 41540490 42810572 43330580 43680560 43850501 43850414 43030344 41810287 41460293 41190400 41540490 Read more

WW 0629 Status Updates
STATUS REPORT ON WW 629 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1903. ..GLEASON..08/30/19 ATTN...WFO...LSX... STATUS REPORT FOR WS 629 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC005-027-119-133-157-163-189-302340- IL . ILLINOIS COUNTIES INCLUDED ARE BOND CLINTON MADISON MONROE RANDOLPH ST. CLAIR WASHINGTON MOC071-093-099-123-179-183-186-187-189-221-510-302340- MO . MISSOURI COUNTIES INCLUDED ARE FRANKLIN IRON JEFFERSON MADISON REYNOLDS ST. CHARLES STE. GENEVIEVE ST. FRANCOIS ST. LOUIS WASHINGTON MISSOURI INDEPENDENT CITIES INCLUDED ARE ST. LOUIS CITY Read more

WW 629 SEVERE TSTM IL MO 302045Z - 310100Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 629 NWS Storm Prediction Center Norman OK 345 PM CDT Fri Aug 30 2019 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Southwest Illinois Eastern Missouri * Effective this Friday afternoon and evening from 345 PM until 800 PM CDT. * Primary threats include... Isolated very large hail events to 2 inches in diameter possible Isolated damaging wind gusts to 70 mph possible A tornado or two possible SUMMARY...Isolated severe storms may further develop and increase in coverage/intensity from east-central/southeast Missouri into southwest Illinois through early evening. Large hail, locally damaging winds and perhaps a tornado will all be possible, particularly along/south of the I-44 corridor. The severe thunderstorm watch area is approximately along and 50 statute miles north and south of a line from 45 miles west northwest of Farmington MO to 35 miles east southeast of Scott Afb IL. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU9). 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 2 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 25020. ...Guyer Read more

MD 1903 CONCERNING SEVERE THUNDERSTORM WATCH 629... FOR PORTIONS OF EASTERN MO INTO SOUTHWESTERN IL
Mesoscale Discussion 1903 NWS Storm Prediction Center Norman OK 0515 PM CDT Fri Aug 30 2019 Areas affected...Portions of eastern MO into southwestern IL Concerning...Severe Thunderstorm Watch 629... Valid 302215Z - 302345Z The severe weather threat for Severe Thunderstorm Watch 629 continues. SUMMARY...Isolated severe threat, including the potential for a brief tornado or two, should continue near and south of the St. Louis metro through the early evening. DISCUSSION...A supercell that formed earlier this afternoon along a surface boundary across eastern MO produced large hail up to 2.5 inches in diameter. This storm has also shown occasional low-level rotation as it approached the St. Louis metro area over the past hour or so. Although low-level flow across this region is not overly strong, it does veer substantially from northeasterly along and just north of the surface boundary to south-southwesterly at mid levels per recent VWPs from KLSX. This veering is contributing to around 40-50 kt of effective bulk shear, which will continue to support organized thunderstorms, including supercells, in the short term. Around 100-150 m2/s2 of effective SRH should also promote some potential for low-level rotation within any supercell that can maintain itself along/near the surface boundary through the early evening. A isolated, brief tornado remains possible, along with a large hail and damaging straight-line wind threat. This isolated severe risk will likely diminish later this evening (generally after 01Z) as the loss of diurnal heating results in a gradually stabilizing boundary layer and diminishing instability. ..Gleason.. 08/30/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LSX... LAT...LON 38219113 38619078 38809034 38978947 38748929 38328930 38188974 37789024 37349063 37339115 38219113 Read more

WW 0629 Status Updates
STATUS FOR WATCH 0629 HAS NOT BEEN ISSUED YET Read more

MD 1902 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR THE I-25 CORRIDOR AND VICINITY
Mesoscale Discussion 1902 NWS Storm Prediction Center Norman OK 0313 PM CDT Fri Aug 30 2019 Areas affected...the I-25 corridor and vicinity Concerning...Severe potential...Watch unlikely Valid 302013Z - 302245Z Probability of Watch Issuance...20 percent SUMMARY...Storms are developing over the Front Range and eastern slopes of the southern Rockies into northern New Mexico. These storms will likely slowly move to the east in the next few hours with severe hail and wind possible. DISCUSSION...Multiple embedded disturbances are evident in west/northwest flow aloft over the central/northern Rockies and vicinity via water vapor imagery. A surface front that was pushed up to the eastern slopes of the Rockies will continue to slowly retreat with the passage of upper-level disturbances aloft and insolation continuing across the High Plains. Upslope, east/southeast flow will continue and with the aforementioned insolation, terrain circulations will become deep enough to establish surface-based convection. Storms may initially be elevated, but should become surface-based this afternoon/evening. Current MLCAPE is around 500 J/kg per mesoanalysis, but this will increase as insolation and moist advection via east/southeast low-level flow continue and likely reach 1000-1500 J/kg by late afternoon/early evening. Effective bulk shear will also increase as mid-level flow strengthens with forecast guidance indicating 25-40 knots. As a result, severe hail and wind will be possible with isolated to scattered storms developing along the I-25 corridor. A watch issuance is unlikely at this time, but convective trends will be monitored. ..Nauslar/Guyer.. 08/30/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PUB...BOU...CYS...ABQ... LAT...LON 35520520 36070512 37080504 39780529 40840547 41270554 41480542 41500457 41040378 39750338 37910346 36610363 35930386 35510412 35320436 35160465 35130501 35320513 35520520 Read more

MD 1901 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF CENTRAL/SOUTHERN INDIANA INTO SOUTHERN OHIO
Mesoscale Discussion 1901 NWS Storm Prediction Center Norman OK 0301 PM CDT Fri Aug 30 2019 Areas affected...Parts of central/southern Indiana into southern Ohio Concerning...Severe potential...Watch unlikely Valid 302001Z - 302200Z Probability of Watch Issuance...5 percent SUMMARY...Scattered strong storms may continue to develop across the region and pose at least some risk for hail and locally damaging wind gusts. Barring signs of the development of a more substantive thunderstorm cluster which could produce more widespread damaging wind gusts, a severe weather watch probably will not be needed. DISCUSSION...A narrow corridor of seasonably moist air has been maintained along and south of a surface front (roughly just south of the Interstate 70 corridor). This appears to be contributing to moderate CAPE on the order of 1500-2000+ J/kg, which is supporting the initiation of thunderstorms near/east of Indianapolis IN into areas near/north of Cincinnati OH, as inhibition continues to weaken with daytime heating. Large-scale mid/upper support for convective development, if any, is unclear. Additionally, the region is generally south of the strong mid-level jet extending across the Great Lakes through the Northeast. However, ambient westerly flow where the storms are initiating appears around 20-30 kts, and this may be enough to contribute to at least some organization to convection as storms increase and intensify in the peak late afternoon instability. Some of these could pose a risk for marginally severe hail and localized potentially damaging wind gusts before diminishing this evening. ..Kerr/Guyer.. 08/30/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PBZ...RLX...ILN...LMK...IND...ILX... LAT...LON 39758653 39838503 39848350 39908235 39678118 38878114 38628268 38868496 38768695 38858771 39288785 39608733 39758653 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Fri Aug 30 2019 Valid 302000Z - 311200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL PLAINS...AND FROM SOUTHEAST MISSOURI EASTWARD INTO SOUTHWEST OHIO... ...SUMMARY... Isolated severe thunderstorms are possible this afternoon and evening across parts of the High Plains this afternoon, into central Kansas overnight, and from southeast Missouri/southern Illinois into southwest Ohio. ...High Plains into central Kansas... Capping remains over most of the area as of 20Z except over the mountains. Ample heating will erode inhibition later today, with isolated marginally severe storms capable of hail and gusty winds from eastern WY into CO, supported by modest northwest flow aloft. Overnight, additional storms in a separate regime are expected to develop from southwest NE into central KS, where warm advection will occur with strengthening southwest 850 mb winds. Lapse rates aloft will remain relatively steep for this time of year, supporting substantial elevated instability. Scattered storms are forecast by many models, and may be capable of marginal hail. If a large enough cluster of storms can form late in the period, severe wind gusts will be possible as well despite the relatively cool boundary layer. As such, have expanded 5% severe probabilities eastward into KS. ...North TX... Storms propagating southward along a long-lived outflow boundary continue to produce gusty winds, though nearly all below severe limits. The presence of 2000 J/kg MLCAPE may support periodic upticks in core intensity, but coverage appears to be decreasing with time as winds aloft are weak. The 18Z FWD sounding also shows a formidable midlevel subsidence inversion. As such, have opted to not add any additional severe probabilities ahead of the outflow boundary. ...MO into OH... A small area of unstable air ahead of an MCV may provide enhanced shear for an isolated supercell, with either brief tornado, damaging wind, or marginal hail threat. For more information see mesoscale discussions 1900 and 1901. ..Jewell.. 08/30/2019 .PREV DISCUSSION... /ISSUED 1129 AM CDT Fri Aug 30 2019/ ...High Plains... Post-frontal upslope flow will be common from northeast New Mexico to eastern Wyoming today, maintaining upper 40s to mid 50s surface dewpoints at peak heating. This should support a plume of modest MLCAPE of 500-1500 J/kg. Stronger/confluent mid-level westerlies will generally be confined to the Wyoming portion of the region where 500-mb flow of 35-45 kt is anticipated, with weaker winds southward along the Front Range. Isolated to scattered thunderstorms are expected to develop by mid to late afternoon over the higher terrain. A few of these storms should become supercellular for a couple hours across eastern Wyoming to northeast Colorado. Abundant MLCIN with eastward extent on the plains and lack of stronger forcing for ascent should keep severe hail and wind coverage low. ...South-central/southeast Missouri to southern Ohio... An MCV continues to move slowly eastward over west-central Missouri late this morning. While this MCV may tend to weaken today, a belt of modestly enhanced low/mid-level winds accompanying the MCV will coincide with a front across south-central/southeast Missouri into southern Illinois. There is a risk for a couple supercells capable of a tornado and isolated damaging winds, particularly along and south/southeast of I-44 in southeast Missouri, as well as southwest Illinois. Farther to the east, a weakly convergent surface front might aid in small multicell clusters capable of locally damaging wind across southern Indiana/northern Kentucky to southern Ohio. ...Southern Plains... Composite outflow/effective front continues to progress south/southwestward across the Texas Panhandle and Red River vicinity. Surface-based late afternoon redevelopment will probably be confined to the Texas Panhandle and possibly far western Oklahoma near the intersection of the composite outflow/front and dryline. A few severe thunderstorms are possible, but weakening deep-layer shear across the region will serve to limit the overall risk. ...Southeast Arizona... On the immediate southern periphery of an upper ridge, isolated thunderstorms are expected to develop over/near the mountains of southeast Arizona and drift west-southwestward with aid of modestly enhanced easterly mid-level winds. A reservoir of moist/unstable air may allow for some relatively stout storms, with strong/gusty outflow winds a possibility as they move across southeast Arizona. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Fri Aug 30 2019 Valid 302000Z - 311200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL PLAINS...AND FROM SOUTHEAST MISSOURI EASTWARD INTO SOUTHWEST OHIO... ...SUMMARY... Isolated severe thunderstorms are possible this afternoon and evening across parts of the High Plains this afternoon, into central Kansas overnight, and from southeast Missouri/southern Illinois into southwest Ohio. ...High Plains into central Kansas... Capping remains over most of the area as of 20Z except over the mountains. Ample heating will erode inhibition later today, with isolated marginally severe storms capable of hail and gusty winds from eastern WY into CO, supported by modest northwest flow aloft. Overnight, additional storms in a separate regime are expected to develop from southwest NE into central KS, where warm advection will occur with strengthening southwest 850 mb winds. Lapse rates aloft will remain relatively steep for this time of year, supporting substantial elevated instability. Scattered storms are forecast by many models, and may be capable of marginal hail. If a large enough cluster of storms can form late in the period, severe wind gusts will be possible as well despite the relatively cool boundary layer. As such, have expanded 5% severe probabilities eastward into KS. ...North TX... Storms propagating southward along a long-lived outflow boundary continue to produce gusty winds, though nearly all below severe limits. The presence of 2000 J/kg MLCAPE may support periodic upticks in core intensity, but coverage appears to be decreasing with time as winds aloft are weak. The 18Z FWD sounding also shows a formidable midlevel subsidence inversion. As such, have opted to not add any additional severe probabilities ahead of the outflow boundary. ...MO into OH... A small area of unstable air ahead of an MCV may provide enhanced shear for an isolated supercell, with either brief tornado, damaging wind, or marginal hail threat. For more information see mesoscale discussions 1900 and 1901. ..Jewell.. 08/30/2019 .PREV DISCUSSION... /ISSUED 1129 AM CDT Fri Aug 30 2019/ ...High Plains... Post-frontal upslope flow will be common from northeast New Mexico to eastern Wyoming today, maintaining upper 40s to mid 50s surface dewpoints at peak heating. This should support a plume of modest MLCAPE of 500-1500 J/kg. Stronger/confluent mid-level westerlies will generally be confined to the Wyoming portion of the region where 500-mb flow of 35-45 kt is anticipated, with weaker winds southward along the Front Range. Isolated to scattered thunderstorms are expected to develop by mid to late afternoon over the higher terrain. A few of these storms should become supercellular for a couple hours across eastern Wyoming to northeast Colorado. Abundant MLCIN with eastward extent on the plains and lack of stronger forcing for ascent should keep severe hail and wind coverage low. ...South-central/southeast Missouri to southern Ohio... An MCV continues to move slowly eastward over west-central Missouri late this morning. While this MCV may tend to weaken today, a belt of modestly enhanced low/mid-level winds accompanying the MCV will coincide with a front across south-central/southeast Missouri into southern Illinois. There is a risk for a couple supercells capable of a tornado and isolated damaging winds, particularly along and south/southeast of I-44 in southeast Missouri, as well as southwest Illinois. Farther to the east, a weakly convergent surface front might aid in small multicell clusters capable of locally damaging wind across southern Indiana/northern Kentucky to southern Ohio. ...Southern Plains... Composite outflow/effective front continues to progress south/southwestward across the Texas Panhandle and Red River vicinity. Surface-based late afternoon redevelopment will probably be confined to the Texas Panhandle and possibly far western Oklahoma near the intersection of the composite outflow/front and dryline. A few severe thunderstorms are possible, but weakening deep-layer shear across the region will serve to limit the overall risk. ...Southeast Arizona... On the immediate southern periphery of an upper ridge, isolated thunderstorms are expected to develop over/near the mountains of southeast Arizona and drift west-southwestward with aid of modestly enhanced easterly mid-level winds. A reservoir of moist/unstable air may allow for some relatively stout storms, with strong/gusty outflow winds a possibility as they move across southeast Arizona. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Fri Aug 30 2019 Valid 302000Z - 311200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL PLAINS...AND FROM SOUTHEAST MISSOURI EASTWARD INTO SOUTHWEST OHIO... ...SUMMARY... Isolated severe thunderstorms are possible this afternoon and evening across parts of the High Plains this afternoon, into central Kansas overnight, and from southeast Missouri/southern Illinois into southwest Ohio. ...High Plains into central Kansas... Capping remains over most of the area as of 20Z except over the mountains. Ample heating will erode inhibition later today, with isolated marginally severe storms capable of hail and gusty winds from eastern WY into CO, supported by modest northwest flow aloft. Overnight, additional storms in a separate regime are expected to develop from southwest NE into central KS, where warm advection will occur with strengthening southwest 850 mb winds. Lapse rates aloft will remain relatively steep for this time of year, supporting substantial elevated instability. Scattered storms are forecast by many models, and may be capable of marginal hail. If a large enough cluster of storms can form late in the period, severe wind gusts will be possible as well despite the relatively cool boundary layer. As such, have expanded 5% severe probabilities eastward into KS. ...North TX... Storms propagating southward along a long-lived outflow boundary continue to produce gusty winds, though nearly all below severe limits. The presence of 2000 J/kg MLCAPE may support periodic upticks in core intensity, but coverage appears to be decreasing with time as winds aloft are weak. The 18Z FWD sounding also shows a formidable midlevel subsidence inversion. As such, have opted to not add any additional severe probabilities ahead of the outflow boundary. ...MO into OH... A small area of unstable air ahead of an MCV may provide enhanced shear for an isolated supercell, with either brief tornado, damaging wind, or marginal hail threat. For more information see mesoscale discussions 1900 and 1901. ..Jewell.. 08/30/2019 .PREV DISCUSSION... /ISSUED 1129 AM CDT Fri Aug 30 2019/ ...High Plains... Post-frontal upslope flow will be common from northeast New Mexico to eastern Wyoming today, maintaining upper 40s to mid 50s surface dewpoints at peak heating. This should support a plume of modest MLCAPE of 500-1500 J/kg. Stronger/confluent mid-level westerlies will generally be confined to the Wyoming portion of the region where 500-mb flow of 35-45 kt is anticipated, with weaker winds southward along the Front Range. Isolated to scattered thunderstorms are expected to develop by mid to late afternoon over the higher terrain. A few of these storms should become supercellular for a couple hours across eastern Wyoming to northeast Colorado. Abundant MLCIN with eastward extent on the plains and lack of stronger forcing for ascent should keep severe hail and wind coverage low. ...South-central/southeast Missouri to southern Ohio... An MCV continues to move slowly eastward over west-central Missouri late this morning. While this MCV may tend to weaken today, a belt of modestly enhanced low/mid-level winds accompanying the MCV will coincide with a front across south-central/southeast Missouri into southern Illinois. There is a risk for a couple supercells capable of a tornado and isolated damaging winds, particularly along and south/southeast of I-44 in southeast Missouri, as well as southwest Illinois. Farther to the east, a weakly convergent surface front might aid in small multicell clusters capable of locally damaging wind across southern Indiana/northern Kentucky to southern Ohio. ...Southern Plains... Composite outflow/effective front continues to progress south/southwestward across the Texas Panhandle and Red River vicinity. Surface-based late afternoon redevelopment will probably be confined to the Texas Panhandle and possibly far western Oklahoma near the intersection of the composite outflow/front and dryline. A few severe thunderstorms are possible, but weakening deep-layer shear across the region will serve to limit the overall risk. ...Southeast Arizona... On the immediate southern periphery of an upper ridge, isolated thunderstorms are expected to develop over/near the mountains of southeast Arizona and drift west-southwestward with aid of modestly enhanced easterly mid-level winds. A reservoir of moist/unstable air may allow for some relatively stout storms, with strong/gusty outflow winds a possibility as they move across southeast Arizona. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Fri Aug 30 2019 Valid 302000Z - 311200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL PLAINS...AND FROM SOUTHEAST MISSOURI EASTWARD INTO SOUTHWEST OHIO... ...SUMMARY... Isolated severe thunderstorms are possible this afternoon and evening across parts of the High Plains this afternoon, into central Kansas overnight, and from southeast Missouri/southern Illinois into southwest Ohio. ...High Plains into central Kansas... Capping remains over most of the area as of 20Z except over the mountains. Ample heating will erode inhibition later today, with isolated marginally severe storms capable of hail and gusty winds from eastern WY into CO, supported by modest northwest flow aloft. Overnight, additional storms in a separate regime are expected to develop from southwest NE into central KS, where warm advection will occur with strengthening southwest 850 mb winds. Lapse rates aloft will remain relatively steep for this time of year, supporting substantial elevated instability. Scattered storms are forecast by many models, and may be capable of marginal hail. If a large enough cluster of storms can form late in the period, severe wind gusts will be possible as well despite the relatively cool boundary layer. As such, have expanded 5% severe probabilities eastward into KS. ...North TX... Storms propagating southward along a long-lived outflow boundary continue to produce gusty winds, though nearly all below severe limits. The presence of 2000 J/kg MLCAPE may support periodic upticks in core intensity, but coverage appears to be decreasing with time as winds aloft are weak. The 18Z FWD sounding also shows a formidable midlevel subsidence inversion. As such, have opted to not add any additional severe probabilities ahead of the outflow boundary. ...MO into OH... A small area of unstable air ahead of an MCV may provide enhanced shear for an isolated supercell, with either brief tornado, damaging wind, or marginal hail threat. For more information see mesoscale discussions 1900 and 1901. ..Jewell.. 08/30/2019 .PREV DISCUSSION... /ISSUED 1129 AM CDT Fri Aug 30 2019/ ...High Plains... Post-frontal upslope flow will be common from northeast New Mexico to eastern Wyoming today, maintaining upper 40s to mid 50s surface dewpoints at peak heating. This should support a plume of modest MLCAPE of 500-1500 J/kg. Stronger/confluent mid-level westerlies will generally be confined to the Wyoming portion of the region where 500-mb flow of 35-45 kt is anticipated, with weaker winds southward along the Front Range. Isolated to scattered thunderstorms are expected to develop by mid to late afternoon over the higher terrain. A few of these storms should become supercellular for a couple hours across eastern Wyoming to northeast Colorado. Abundant MLCIN with eastward extent on the plains and lack of stronger forcing for ascent should keep severe hail and wind coverage low. ...South-central/southeast Missouri to southern Ohio... An MCV continues to move slowly eastward over west-central Missouri late this morning. While this MCV may tend to weaken today, a belt of modestly enhanced low/mid-level winds accompanying the MCV will coincide with a front across south-central/southeast Missouri into southern Illinois. There is a risk for a couple supercells capable of a tornado and isolated damaging winds, particularly along and south/southeast of I-44 in southeast Missouri, as well as southwest Illinois. Farther to the east, a weakly convergent surface front might aid in small multicell clusters capable of locally damaging wind across southern Indiana/northern Kentucky to southern Ohio. ...Southern Plains... Composite outflow/effective front continues to progress south/southwestward across the Texas Panhandle and Red River vicinity. Surface-based late afternoon redevelopment will probably be confined to the Texas Panhandle and possibly far western Oklahoma near the intersection of the composite outflow/front and dryline. A few severe thunderstorms are possible, but weakening deep-layer shear across the region will serve to limit the overall risk. ...Southeast Arizona... On the immediate southern periphery of an upper ridge, isolated thunderstorms are expected to develop over/near the mountains of southeast Arizona and drift west-southwestward with aid of modestly enhanced easterly mid-level winds. A reservoir of moist/unstable air may allow for some relatively stout storms, with strong/gusty outflow winds a possibility as they move across southeast Arizona. Read more

No watches are valid as of Fri Aug 30 19:29:07 UTC 2019.

MD 1900 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR SOUTH CENTRAL THROUGH EAST CENTRAL MISSOURI
Mesoscale Discussion 1900 NWS Storm Prediction Center Norman OK 0226 PM CDT Fri Aug 30 2019 Areas affected...South central through east central Missouri Concerning...Severe potential...Watch unlikely Valid 301926Z - 302130Z Probability of Watch Issuance...20 percent SUMMARY...Strong thunderstorms may impact areas near/southeast of Interstate 44, from south central Missouri into the St. Louis Metropolitan area, by 4-6 PM. This may include potential for a relatively brief, weak tornado or two. Barring increasing signs for the development of a more substantive tornado threat, a severe weather watch will probably not be needed. DISCUSSION...Weak mid-level troughing appears to be slowly turning eastward across central/southern Missouri. An embedded mesoscale convective vortex to the southwest of Jefferson City is supporting continuing convection, with newer thunderstorm development initiating near Vichy, in the vicinity of a surface low center along a weak frontal zone extending northeastward into the St. Louis Metropolitan area. Additional thunderstorms also appear to be forming west of Fort Leonard Wood, in closer proximity to the lower/mid tropospheric low center. Mixed-layer CAPE still appears relatively modest and confined to a narrow corridor along the frontal zone, but it does appear to be increasing with breaks in overcast. Within the next few hours, it may exceed 1000 J/kg, in the presence of at least moderate deep-layer shear beneath a belt of 30-40 kt southwesterly flow around the 500 level. This regime may become supportive of organized convection, including discrete supercells. Although low-level wind fields (and hodographs) are weak, there does appear potential for at least relatively brief, weak tornadoes, generally in association with the intensification of ambient vertical vorticity along the surface boundary. Otherwise, stronger storms may pose some risk for hail and locally stronger surface gusts, before weakening this evening. ..Kerr/Guyer.. 08/30/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LSX...SGF... LAT...LON 37509129 36999186 37009247 37569257 38189195 38559126 38579084 38789051 38729002 38159005 37509129 Read more

MD 1899 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR NORTH CENTRAL TEXAS
Mesoscale Discussion 1899 NWS Storm Prediction Center Norman OK 1245 PM CDT Fri Aug 30 2019 Areas affected...North central Texas Concerning...Severe potential...Watch unlikely Valid 301745Z - 301945Z Probability of Watch Issuance...20 percent SUMMARY...Strong thunderstorms may impact much of the Dallas-Fort Worth Metroplex by 2-4 PM, accompanied by gusty surface winds, some of which could approach or briefly exceed severe limits. Barring substantive further organization of storms suggesting increasing potential for widespread severe gusts, a severe weather watch issuance is not anticipated. DISCUSSION...A gradual intensification of thunderstorm development appears underway, south of the Red River, to the northwest and north of the Dallas-Fort Worth Metroplex. This appears largely supported by lifted along a southward advancing, convectively generated surface cold pool, perhaps aided by weak low-level warm advection. It appears to be occurring beneath a weak mid-level ridge axis (around 700 mb), where mean wind fields and vertical shear are generally weak. However, light west-northwesterly flow further aloft probably will support a continued southward propagation into the Metroplex during the next few hours. Low-level lapse rates are becoming fairly steep with continued insolation and boundary-layer mixing ahead of the cold pool. With surface temperatures already exceeding 90 F, dew points near 70 F are appear to be contributing to CAPE on the order of 2000 J/kg. Inflow of this air seems likely to maintain vigorous thunderstorm development, with further intensification possible, accompanied by increasing potential for strong surface gusts in association with localized downbursts, as well as along the strengthening gust front. ..Kerr/Guyer.. 08/30/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...SHV...FWD... LAT...LON 33239823 33229718 33389657 33639624 33719558 33009544 32209654 32199783 32749866 33239823 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Fri Aug 30 2019 Valid 311200Z - 011200Z ...NO CRITICAL AREAS... Tomorrow's fire weather forecast remains on track, with no changes needed at this time. See previous discussion below for more information. ..Elliott.. 08/30/2019 .PREV DISCUSSION... /ISSUED 0146 AM CDT Fri Aug 30 2019/ ...Synopsis... The developing mid-level ridge on Day 1 will become fully fortified across the western CONUS on Day 2/Saturday. Weaker winds aloft and associated synoptic scale forcing suggest that relatively quiescent fire weather conditions will prevail across much of the western CONUS. The only minor exceptions at this time appear to be around the Snake River Plain/Great Divide Basin areas, where diurnal boundary layer mixing may encourage locally elevated wind/RH conditions across terrain favoring locations, and in parts of northwest New Mexico, where a few dry lightning strikes atop modestly dry fuels may support a few ignitions. ...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 1230 PM CDT Fri Aug 30 2019 Valid 311200Z - 011200Z ...NO CRITICAL AREAS... Tomorrow's fire weather forecast remains on track, with no changes needed at this time. See previous discussion below for more information. ..Elliott.. 08/30/2019 .PREV DISCUSSION... /ISSUED 0146 AM CDT Fri Aug 30 2019/ ...Synopsis... The developing mid-level ridge on Day 1 will become fully fortified across the western CONUS on Day 2/Saturday. Weaker winds aloft and associated synoptic scale forcing suggest that relatively quiescent fire weather conditions will prevail across much of the western CONUS. The only minor exceptions at this time appear to be around the Snake River Plain/Great Divide Basin areas, where diurnal boundary layer mixing may encourage locally elevated wind/RH conditions across terrain favoring locations, and in parts of northwest New Mexico, where a few dry lightning strikes atop modestly dry fuels may support a few ignitions. ...Please see www.spc.noaa.gov/fire for graphic product... Read more