Severe Storms

MD 1745 CONCERNING SEVERE POTENTIAL...SEVERE THUNDERSTORM WATCH LIKELY FOR SOUTHEAST ND...EASTERN SD AND EXTREME SOUTHWEST MN
Mesoscale Discussion 1745 NWS Storm Prediction Center Norman OK 0118 PM CDT Thu Aug 15 2019 Areas affected...southeast ND...eastern SD and extreme southwest MN Concerning...Severe potential...Severe Thunderstorm Watch likely Valid 151818Z - 151945Z Probability of Watch Issuance...80 percent SUMMARY...Large hail and damaging wind gusts will be possible this afternoon and evening across parts of southeast North Dakota into eastern South Dakota and perhaps southwest Minnesota. DISCUSSION...Modest heating to the east of a surface cold front/trough across southeast ND into eastern SD will continue this afternoon. Weak to moderate instability is currently present across the region, aided by low 60s surface dewpoints beneath midlevel lapse rates around 6.5-7.5 C/km. A shortwave impulse will continue eastward across the Dakotas this afternoon, providing greater forcing for ascent and helping to erode remaining MLCINH. This should result in increasing convective coverage and intensity along the surface boundary over the next few hours. High-based cells may initially develop, supported by 40 kt effective shear. An attendant threat of large hail and damaging downburst winds is possible with these initial storms. As linear ascent increases, upscale growth into one or more bowing segments is expected, increasing damaging wind potential into this evening with eastward extent. A severe thunderstorm watch will likely be needed for portions of the region by 20z. ..Leitman/Grams.. 08/15/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MPX...FGF...FSD...ABR...BIS...UNR... LAT...LON 46559740 45429632 44549613 43759621 43119715 43019815 43029881 43240007 43990083 44570074 45659996 46399930 46539894 46669824 46559740 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1228 PM CDT Thu Aug 15 2019 Valid 161200Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL HIGH PLAINS...CENTRAL PLAINS...AND MID MS VALLEY... ...SUMMARY... Severe storms are possible from the central High Plains across Kansas and Missouri and into western Illinois Friday. ...Synopsis... A belt of enhanced westerly flow aloft will extend from the northern Great Basin eastward into the middle MS Valley early Friday morning, just ahead of a low-amplitude shortwave trough. This shortwave (and associated cold temperatures aloft) is expected to continue eastward across the central Plains with the attendant jet streak progressing eastward just ahead of it. Farther north, a strong shortwave trough is expected to move into the Canadian Prairie Provinces and northern Rockies late Friday evening through early Saturday morning. Early Friday morning surface pattern will likely feature a low centered near the central MN/WI border with a cold front extending southwestward into central KS and then back northwestward into northeast CO. A moist air mass will be in place south of this outflow-reinforced boundary, with afternoon dewpoints in the mid to upper 60s. Low 70s dewpoints are possible in the immediate vicinity of this composite boundary, which is expected to remain largely stationary across central KS and central MO throughout the day. This front is expected to be the focus for severe thunderstorms during the late afternoon/early evening and continuing overnight. Severe thunderstorms are also possible across southern portions of northern High Plains and central High Plains during the afternoon and evening. ...Central Plains into the Middle MS Valley... Showers and thunderstorms (remnant from an overnight MCS across KS) will likely be ongoing early Friday morning across central/southern MO. Outflow from these storms (which will likely extend back into central KS) will act as the effective front separating the warm and moist conditions across southern KS/MO/IL and the southern Plains from the cooler conditions across northern KS/MO and the remainder of the central Plains and middle MS Valley. This front is expected to act as the primary corridor for thunderstorm development, although two different forcing mechanisms appear possible. The first potential impetus for convective initiation is convergence along the front amidst diurnal destabilization. However, given the relatively warm layer between 850 and 700 mb and lack of stronger large-scale forcing for ascent, there is some question whether storms will be able to develop along the front during the late afternoon/early evening. If storms do develop, very strong buoyancy will contribute to strong updrafts capable of large hail and strong wind gusts. The lack of stronger vertical shear suggest storms should quickly become outflow dominant. Given the presence of a surface boundary, a brief tornado or two is also possible. The second impetus for convective initiation near the front is the low-level jet, which is expected to strengthen across the TX Panhandle, western OK, and southern KS Friday evening. Warm-air advection into the frontal zone is expected to result in the development of elevated thunderstorms from east-central KS, central MO, and far west-central IL. Mid-level flow will be stronger here and the potential exist for more organized storms capable of large hail. Isolated very large hail (i.e. diameter greater than 2") is possible. ...Northern/Central High Plains... Isolated thunderstorms will likely be ongoing across portions of the NE Panhandle and vicinity as a subtle shortwave move through the region. Higher thunderstorm coverage is anticipated during the afternoon when storms are expected to develop amidst upslope flow into the lee trough. The approaching shortwave trough will provide additional support for vertical ascent. Most probable location for initial storm development is across northeast/east-central CO and vicinity, with storm motion then taking the storms into western KS. Development a forward-propagating MCS is possible, with the frontal zone acting a favored corridor for propagation and the strengthening low-level jet providing additional moisture. Higher probabilities may be needed is subsequent outlooks if this potential becomes more probable. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% SIG - Slight Hail: 15% SIG - Slight ..Mosier.. 08/15/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1228 PM CDT Thu Aug 15 2019 Valid 161200Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL HIGH PLAINS...CENTRAL PLAINS...AND MID MS VALLEY... ...SUMMARY... Severe storms are possible from the central High Plains across Kansas and Missouri and into western Illinois Friday. ...Synopsis... A belt of enhanced westerly flow aloft will extend from the northern Great Basin eastward into the middle MS Valley early Friday morning, just ahead of a low-amplitude shortwave trough. This shortwave (and associated cold temperatures aloft) is expected to continue eastward across the central Plains with the attendant jet streak progressing eastward just ahead of it. Farther north, a strong shortwave trough is expected to move into the Canadian Prairie Provinces and northern Rockies late Friday evening through early Saturday morning. Early Friday morning surface pattern will likely feature a low centered near the central MN/WI border with a cold front extending southwestward into central KS and then back northwestward into northeast CO. A moist air mass will be in place south of this outflow-reinforced boundary, with afternoon dewpoints in the mid to upper 60s. Low 70s dewpoints are possible in the immediate vicinity of this composite boundary, which is expected to remain largely stationary across central KS and central MO throughout the day. This front is expected to be the focus for severe thunderstorms during the late afternoon/early evening and continuing overnight. Severe thunderstorms are also possible across southern portions of northern High Plains and central High Plains during the afternoon and evening. ...Central Plains into the Middle MS Valley... Showers and thunderstorms (remnant from an overnight MCS across KS) will likely be ongoing early Friday morning across central/southern MO. Outflow from these storms (which will likely extend back into central KS) will act as the effective front separating the warm and moist conditions across southern KS/MO/IL and the southern Plains from the cooler conditions across northern KS/MO and the remainder of the central Plains and middle MS Valley. This front is expected to act as the primary corridor for thunderstorm development, although two different forcing mechanisms appear possible. The first potential impetus for convective initiation is convergence along the front amidst diurnal destabilization. However, given the relatively warm layer between 850 and 700 mb and lack of stronger large-scale forcing for ascent, there is some question whether storms will be able to develop along the front during the late afternoon/early evening. If storms do develop, very strong buoyancy will contribute to strong updrafts capable of large hail and strong wind gusts. The lack of stronger vertical shear suggest storms should quickly become outflow dominant. Given the presence of a surface boundary, a brief tornado or two is also possible. The second impetus for convective initiation near the front is the low-level jet, which is expected to strengthen across the TX Panhandle, western OK, and southern KS Friday evening. Warm-air advection into the frontal zone is expected to result in the development of elevated thunderstorms from east-central KS, central MO, and far west-central IL. Mid-level flow will be stronger here and the potential exist for more organized storms capable of large hail. Isolated very large hail (i.e. diameter greater than 2") is possible. ...Northern/Central High Plains... Isolated thunderstorms will likely be ongoing across portions of the NE Panhandle and vicinity as a subtle shortwave move through the region. Higher thunderstorm coverage is anticipated during the afternoon when storms are expected to develop amidst upslope flow into the lee trough. The approaching shortwave trough will provide additional support for vertical ascent. Most probable location for initial storm development is across northeast/east-central CO and vicinity, with storm motion then taking the storms into western KS. Development a forward-propagating MCS is possible, with the frontal zone acting a favored corridor for propagation and the strengthening low-level jet providing additional moisture. Higher probabilities may be needed is subsequent outlooks if this potential becomes more probable. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% SIG - Slight Hail: 15% SIG - Slight ..Mosier.. 08/15/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1228 PM CDT Thu Aug 15 2019 Valid 161200Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL HIGH PLAINS...CENTRAL PLAINS...AND MID MS VALLEY... ...SUMMARY... Severe storms are possible from the central High Plains across Kansas and Missouri and into western Illinois Friday. ...Synopsis... A belt of enhanced westerly flow aloft will extend from the northern Great Basin eastward into the middle MS Valley early Friday morning, just ahead of a low-amplitude shortwave trough. This shortwave (and associated cold temperatures aloft) is expected to continue eastward across the central Plains with the attendant jet streak progressing eastward just ahead of it. Farther north, a strong shortwave trough is expected to move into the Canadian Prairie Provinces and northern Rockies late Friday evening through early Saturday morning. Early Friday morning surface pattern will likely feature a low centered near the central MN/WI border with a cold front extending southwestward into central KS and then back northwestward into northeast CO. A moist air mass will be in place south of this outflow-reinforced boundary, with afternoon dewpoints in the mid to upper 60s. Low 70s dewpoints are possible in the immediate vicinity of this composite boundary, which is expected to remain largely stationary across central KS and central MO throughout the day. This front is expected to be the focus for severe thunderstorms during the late afternoon/early evening and continuing overnight. Severe thunderstorms are also possible across southern portions of northern High Plains and central High Plains during the afternoon and evening. ...Central Plains into the Middle MS Valley... Showers and thunderstorms (remnant from an overnight MCS across KS) will likely be ongoing early Friday morning across central/southern MO. Outflow from these storms (which will likely extend back into central KS) will act as the effective front separating the warm and moist conditions across southern KS/MO/IL and the southern Plains from the cooler conditions across northern KS/MO and the remainder of the central Plains and middle MS Valley. This front is expected to act as the primary corridor for thunderstorm development, although two different forcing mechanisms appear possible. The first potential impetus for convective initiation is convergence along the front amidst diurnal destabilization. However, given the relatively warm layer between 850 and 700 mb and lack of stronger large-scale forcing for ascent, there is some question whether storms will be able to develop along the front during the late afternoon/early evening. If storms do develop, very strong buoyancy will contribute to strong updrafts capable of large hail and strong wind gusts. The lack of stronger vertical shear suggest storms should quickly become outflow dominant. Given the presence of a surface boundary, a brief tornado or two is also possible. The second impetus for convective initiation near the front is the low-level jet, which is expected to strengthen across the TX Panhandle, western OK, and southern KS Friday evening. Warm-air advection into the frontal zone is expected to result in the development of elevated thunderstorms from east-central KS, central MO, and far west-central IL. Mid-level flow will be stronger here and the potential exist for more organized storms capable of large hail. Isolated very large hail (i.e. diameter greater than 2") is possible. ...Northern/Central High Plains... Isolated thunderstorms will likely be ongoing across portions of the NE Panhandle and vicinity as a subtle shortwave move through the region. Higher thunderstorm coverage is anticipated during the afternoon when storms are expected to develop amidst upslope flow into the lee trough. The approaching shortwave trough will provide additional support for vertical ascent. Most probable location for initial storm development is across northeast/east-central CO and vicinity, with storm motion then taking the storms into western KS. Development a forward-propagating MCS is possible, with the frontal zone acting a favored corridor for propagation and the strengthening low-level jet providing additional moisture. Higher probabilities may be needed is subsequent outlooks if this potential becomes more probable. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% SIG - Slight Hail: 15% SIG - Slight ..Mosier.. 08/15/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1228 PM CDT Thu Aug 15 2019 Valid 161200Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL HIGH PLAINS...CENTRAL PLAINS...AND MID MS VALLEY... ...SUMMARY... Severe storms are possible from the central High Plains across Kansas and Missouri and into western Illinois Friday. ...Synopsis... A belt of enhanced westerly flow aloft will extend from the northern Great Basin eastward into the middle MS Valley early Friday morning, just ahead of a low-amplitude shortwave trough. This shortwave (and associated cold temperatures aloft) is expected to continue eastward across the central Plains with the attendant jet streak progressing eastward just ahead of it. Farther north, a strong shortwave trough is expected to move into the Canadian Prairie Provinces and northern Rockies late Friday evening through early Saturday morning. Early Friday morning surface pattern will likely feature a low centered near the central MN/WI border with a cold front extending southwestward into central KS and then back northwestward into northeast CO. A moist air mass will be in place south of this outflow-reinforced boundary, with afternoon dewpoints in the mid to upper 60s. Low 70s dewpoints are possible in the immediate vicinity of this composite boundary, which is expected to remain largely stationary across central KS and central MO throughout the day. This front is expected to be the focus for severe thunderstorms during the late afternoon/early evening and continuing overnight. Severe thunderstorms are also possible across southern portions of northern High Plains and central High Plains during the afternoon and evening. ...Central Plains into the Middle MS Valley... Showers and thunderstorms (remnant from an overnight MCS across KS) will likely be ongoing early Friday morning across central/southern MO. Outflow from these storms (which will likely extend back into central KS) will act as the effective front separating the warm and moist conditions across southern KS/MO/IL and the southern Plains from the cooler conditions across northern KS/MO and the remainder of the central Plains and middle MS Valley. This front is expected to act as the primary corridor for thunderstorm development, although two different forcing mechanisms appear possible. The first potential impetus for convective initiation is convergence along the front amidst diurnal destabilization. However, given the relatively warm layer between 850 and 700 mb and lack of stronger large-scale forcing for ascent, there is some question whether storms will be able to develop along the front during the late afternoon/early evening. If storms do develop, very strong buoyancy will contribute to strong updrafts capable of large hail and strong wind gusts. The lack of stronger vertical shear suggest storms should quickly become outflow dominant. Given the presence of a surface boundary, a brief tornado or two is also possible. The second impetus for convective initiation near the front is the low-level jet, which is expected to strengthen across the TX Panhandle, western OK, and southern KS Friday evening. Warm-air advection into the frontal zone is expected to result in the development of elevated thunderstorms from east-central KS, central MO, and far west-central IL. Mid-level flow will be stronger here and the potential exist for more organized storms capable of large hail. Isolated very large hail (i.e. diameter greater than 2") is possible. ...Northern/Central High Plains... Isolated thunderstorms will likely be ongoing across portions of the NE Panhandle and vicinity as a subtle shortwave move through the region. Higher thunderstorm coverage is anticipated during the afternoon when storms are expected to develop amidst upslope flow into the lee trough. The approaching shortwave trough will provide additional support for vertical ascent. Most probable location for initial storm development is across northeast/east-central CO and vicinity, with storm motion then taking the storms into western KS. Development a forward-propagating MCS is possible, with the frontal zone acting a favored corridor for propagation and the strengthening low-level jet providing additional moisture. Higher probabilities may be needed is subsequent outlooks if this potential becomes more probable. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% SIG - Slight Hail: 15% SIG - Slight ..Mosier.. 08/15/2019 Read more

MD 1744 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PORTIONS OF EASTERN OH...WESTERN/CENTRAL PA...FAR SOUTHERN NY...WESTERN MD...NORTHERN/EASTERN WV...AND NORTHERN/CENTRAL VA
Mesoscale Discussion 1744 NWS Storm Prediction Center Norman OK 1215 PM CDT Thu Aug 15 2019 Areas affected...Portions of eastern OH...western/central PA...far southern NY...western MD...northern/eastern WV...and northern/central VA Concerning...Severe potential...Watch possible Valid 151715Z - 151915Z Probability of Watch Issuance...40 percent SUMMARY...The threat for large hail and damaging winds with scattered storms should continue to increase this afternoon. Watch issuance is possible, with a relatively greater chance from eastern Ohio into Pennsylvania. DISCUSSION...Convection will likely continue to increase in coverage and intensity this afternoon across eastern OH into parts of the Mid-Atlantic as a weak shortwave trough moves eastward across the Great Lakes and OH Valley through this evening. Low-level flow over these regions remains generally weak, but west-southwesterly winds do strengthen through mid levels. Resultant 35-45 kt of effective bulk shear will likely promote discrete storm modes, with some supercell structures possible. A moist low-level airmass is also present across these areas per 12Z soundings and latest surface observations. Additional diurnal heating through the remainder of the afternoon will contribute to moderate instability, with MLCAPE of 1500-2000 J/kg expected. Somewhat greater storm coverage may be realized across eastern OH into western/central PA and vicinity, which will be closer to the modest large-scale ascent associated with the approaching shortwave trough. Farther south into western MD and northern/central VA, weak low-level easterly upslope flow has encouraged isolated storms along/east of the Blue Ridge Mountains. A similar instability/shear parameter space will exist across both regions, with isolated large hail and damaging wind gusts possible. Additional storms may form along a lake breeze in northeastern OH/northwestern PA, and along a weak surface trough in eastern OH. Observational trends will continue to be closely monitored for possible watch issuance this afternoon. Severe Thunderstorm Watch potential seems relatively greater across parts of eastern OH into PA and vicinity based on latest short-term model trends. ..Gleason/Grams.. 08/15/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BGM...AKQ...BUF...CTP...LWX...RNK...PBZ...CLE... LAT...LON 41687628 41397619 41007628 38967718 37997749 37377785 37257844 37447893 37937909 38877903 39467940 39848020 40548141 41058213 41258209 41508131 42068004 42297882 42287759 42027675 41687628 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1134 AM CDT Thu Aug 15 2019 Valid 151700Z - 161200Z At least locally elevated fire weather conditions may expand into portions of northwest Colorado, west of the Rockies in the lower terrain areas this afternoon. However, the sparse and relatively brief nature of these conditions precludes an expansion of the elevated delineation into this area. Otherwise, the previous forecast remains on track. Please see below for details. ..Squitieri.. 08/15/2019 .PREV DISCUSSION... /ISSUED 1246 AM CDT Thu Aug 15 2019/ ...Synopsis... A couple of shortwave troughs - one over the northern Plains and another Idaho - will gradually amplify southward/southeastward during the period. These shortwaves will result in a belt of enhanced mid-level flow extending from Oregon east-southeastward to Nebraska. This flow will strengthen atop a warming, yet dry low-level airmass across portions of Idaho and Wyoming, resulting in elevated to locally critical fire weather conditions. ...Eastern Idaho into southern Wyoming... Beneath strengthening mid-level flow, insolation and vertical mixing processes during peak heating hours will result in areas of 15-25 mph westerly surface flow - strongest across the Snake River Plain and areas of southern Wyoming. Meanwhile, RH values will fall to around 15% or so even though models/point forecast soundings indicate the potential for mid/high level clouds to slow boundary layer mixing some. Given areas of dry fuels across the region, atmospheric conditions are most consistent with elevated fire weather thresholds, though a few areas of critical fire weather may occur on a localized basis. ...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 1134 AM CDT Thu Aug 15 2019 Valid 151700Z - 161200Z At least locally elevated fire weather conditions may expand into portions of northwest Colorado, west of the Rockies in the lower terrain areas this afternoon. However, the sparse and relatively brief nature of these conditions precludes an expansion of the elevated delineation into this area. Otherwise, the previous forecast remains on track. Please see below for details. ..Squitieri.. 08/15/2019 .PREV DISCUSSION... /ISSUED 1246 AM CDT Thu Aug 15 2019/ ...Synopsis... A couple of shortwave troughs - one over the northern Plains and another Idaho - will gradually amplify southward/southeastward during the period. These shortwaves will result in a belt of enhanced mid-level flow extending from Oregon east-southeastward to Nebraska. This flow will strengthen atop a warming, yet dry low-level airmass across portions of Idaho and Wyoming, resulting in elevated to locally critical fire weather conditions. ...Eastern Idaho into southern Wyoming... Beneath strengthening mid-level flow, insolation and vertical mixing processes during peak heating hours will result in areas of 15-25 mph westerly surface flow - strongest across the Snake River Plain and areas of southern Wyoming. Meanwhile, RH values will fall to around 15% or so even though models/point forecast soundings indicate the potential for mid/high level clouds to slow boundary layer mixing some. Given areas of dry fuels across the region, atmospheric conditions are most consistent with elevated fire weather thresholds, though a few areas of critical fire weather may occur on a localized basis. ...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 1134 AM CDT Thu Aug 15 2019 Valid 151700Z - 161200Z At least locally elevated fire weather conditions may expand into portions of northwest Colorado, west of the Rockies in the lower terrain areas this afternoon. However, the sparse and relatively brief nature of these conditions precludes an expansion of the elevated delineation into this area. Otherwise, the previous forecast remains on track. Please see below for details. ..Squitieri.. 08/15/2019 .PREV DISCUSSION... /ISSUED 1246 AM CDT Thu Aug 15 2019/ ...Synopsis... A couple of shortwave troughs - one over the northern Plains and another Idaho - will gradually amplify southward/southeastward during the period. These shortwaves will result in a belt of enhanced mid-level flow extending from Oregon east-southeastward to Nebraska. This flow will strengthen atop a warming, yet dry low-level airmass across portions of Idaho and Wyoming, resulting in elevated to locally critical fire weather conditions. ...Eastern Idaho into southern Wyoming... Beneath strengthening mid-level flow, insolation and vertical mixing processes during peak heating hours will result in areas of 15-25 mph westerly surface flow - strongest across the Snake River Plain and areas of southern Wyoming. Meanwhile, RH values will fall to around 15% or so even though models/point forecast soundings indicate the potential for mid/high level clouds to slow boundary layer mixing some. Given areas of dry fuels across the region, atmospheric conditions are most consistent with elevated fire weather thresholds, though a few areas of critical fire weather may occur on a localized basis. ...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 1134 AM CDT Thu Aug 15 2019 Valid 151700Z - 161200Z At least locally elevated fire weather conditions may expand into portions of northwest Colorado, west of the Rockies in the lower terrain areas this afternoon. However, the sparse and relatively brief nature of these conditions precludes an expansion of the elevated delineation into this area. Otherwise, the previous forecast remains on track. Please see below for details. ..Squitieri.. 08/15/2019 .PREV DISCUSSION... /ISSUED 1246 AM CDT Thu Aug 15 2019/ ...Synopsis... A couple of shortwave troughs - one over the northern Plains and another Idaho - will gradually amplify southward/southeastward during the period. These shortwaves will result in a belt of enhanced mid-level flow extending from Oregon east-southeastward to Nebraska. This flow will strengthen atop a warming, yet dry low-level airmass across portions of Idaho and Wyoming, resulting in elevated to locally critical fire weather conditions. ...Eastern Idaho into southern Wyoming... Beneath strengthening mid-level flow, insolation and vertical mixing processes during peak heating hours will result in areas of 15-25 mph westerly surface flow - strongest across the Snake River Plain and areas of southern Wyoming. Meanwhile, RH values will fall to around 15% or so even though models/point forecast soundings indicate the potential for mid/high level clouds to slow boundary layer mixing some. Given areas of dry fuels across the region, atmospheric conditions are most consistent with elevated fire weather thresholds, though a few areas of critical fire weather may occur on a localized basis. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Thu Aug 15 2019 Valid 151630Z - 161200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS EASTERN KS... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF NORTHERN/CENTRAL GREAT PLAINS AND NORTHEAST STATES... ...SUMMARY... Severe thunderstorms are most likely to be centered on eastern Kansas during the late afternoon and evening. Severe hail and wind gusts may be significant with a few tornadoes also possible. ...Central/eastern KS vicinity... An MCS is ongoing across eastern NE with a trailing composite outflow/cold front extending into far northwest KS. Waning low-level warm advection through the next few hours should inhibit substantial strengthening across the Lower MS Valley. The trailing outflow will be the primary focus for late afternoon to early evening redevelopment. Low-level convergence should support initial storms from north-central into northeast KS. A plume of upper 60s surface dew points at present across central KS will be maintained as richer boundary-layer moisture advects north from OK, beneath the eastern extent of the elevated mixed layer. Ample diabatic heating will yield large buoyancy with MLCAPE likely reaching 2500-3500 J/kg. A veering wind profile with height will support initial supercells, with hodograph enlargement occurring through the evening as a southwesterly low-level jet intensifies. The setup should foster a risk for very large hail and a few tornadoes. However, the overall mode may tend to grow upscale into clusters and an MCS relatively quickly given the strengthening forcing for ascent during the evening. This may result in the predominant threat becoming severe wind gusts (a few of which may be significant) as an MCS develops bowing structures across eastern KS towards western MO/northern OK. Overall severe threat should subside overnight with the most likely MCS track approaching the Ozark Plateau. 12Z non-HRRR HREF members are more consistent with this overall scenario than recent HRRR runs, with the parent RAP maintaining more pronounced MLCIN in much of the warm sector. Nevertheless, an Enhanced Slight Risk appears warranted given the potential for a higher-end intensity/coverage scenario. ...SD vicinity... A low-amplitude shortwave trough and attendant surface boundary will move east across the Dakotas. Ample diabatic heating is underway downstream across central to eastern SD north of the NE MCS. Presence of upper 50s to low 60s boundary-layer dew points will support MLCAPE of at least 1500-2000 J/kg. While low-level shear will be weak, robust speed shear from 700 mb on up will foster an elongated mid/upper-level hodograph favorable for mid-level rotation and an eventual eastward-progressing MCS with potential for a brief bow. Initial large hail transitioning to predominant severe wind gusts should be the main threats before activity weakens in western MN. ...Eastern WY and NE Panhandle... Residual low-level moisture (corridor of upper 50s surface dew points) within a weak upslope regime north of the trailing composite outflow/cold front over northeast CO will support a conditional supercell environment favorable for large hail. However, storm coverage appears likely to be rather isolated at peak heating in the wake of the shortwave trough crossing the Dakotas. Greater confidence in storms exists early Friday morning ahead of the next upstream shortwave impulse. ...Eastern OH and PA vicinity... A low-amplitude upper trough from eastern Lake Superior to western OH will gradually move east with an attendant weak surface cyclone drifting across northern OH. Relatively cool temperatures aloft atop a plume of mid to upper 60s surface dew points should result in MLCAPE reaching 1500-2000 J/kg during the next few hours. Though low-level flow/shear will be weak, there will be sufficient deep-layer vertical shear for multiple mid-level rotating updrafts as scattered storms develop from the Upper OH Valley/Lower Great Lakes regions across the lee of the Appalachians. Convection should remain predominantly discrete, yielding a risk for both severe hail and damaging winds, with these threats waning after dusk. ..Grams/Gleason.. 08/15/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Thu Aug 15 2019 Valid 151630Z - 161200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS EASTERN KS... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF NORTHERN/CENTRAL GREAT PLAINS AND NORTHEAST STATES... ...SUMMARY... Severe thunderstorms are most likely to be centered on eastern Kansas during the late afternoon and evening. Severe hail and wind gusts may be significant with a few tornadoes also possible. ...Central/eastern KS vicinity... An MCS is ongoing across eastern NE with a trailing composite outflow/cold front extending into far northwest KS. Waning low-level warm advection through the next few hours should inhibit substantial strengthening across the Lower MS Valley. The trailing outflow will be the primary focus for late afternoon to early evening redevelopment. Low-level convergence should support initial storms from north-central into northeast KS. A plume of upper 60s surface dew points at present across central KS will be maintained as richer boundary-layer moisture advects north from OK, beneath the eastern extent of the elevated mixed layer. Ample diabatic heating will yield large buoyancy with MLCAPE likely reaching 2500-3500 J/kg. A veering wind profile with height will support initial supercells, with hodograph enlargement occurring through the evening as a southwesterly low-level jet intensifies. The setup should foster a risk for very large hail and a few tornadoes. However, the overall mode may tend to grow upscale into clusters and an MCS relatively quickly given the strengthening forcing for ascent during the evening. This may result in the predominant threat becoming severe wind gusts (a few of which may be significant) as an MCS develops bowing structures across eastern KS towards western MO/northern OK. Overall severe threat should subside overnight with the most likely MCS track approaching the Ozark Plateau. 12Z non-HRRR HREF members are more consistent with this overall scenario than recent HRRR runs, with the parent RAP maintaining more pronounced MLCIN in much of the warm sector. Nevertheless, an Enhanced Slight Risk appears warranted given the potential for a higher-end intensity/coverage scenario. ...SD vicinity... A low-amplitude shortwave trough and attendant surface boundary will move east across the Dakotas. Ample diabatic heating is underway downstream across central to eastern SD north of the NE MCS. Presence of upper 50s to low 60s boundary-layer dew points will support MLCAPE of at least 1500-2000 J/kg. While low-level shear will be weak, robust speed shear from 700 mb on up will foster an elongated mid/upper-level hodograph favorable for mid-level rotation and an eventual eastward-progressing MCS with potential for a brief bow. Initial large hail transitioning to predominant severe wind gusts should be the main threats before activity weakens in western MN. ...Eastern WY and NE Panhandle... Residual low-level moisture (corridor of upper 50s surface dew points) within a weak upslope regime north of the trailing composite outflow/cold front over northeast CO will support a conditional supercell environment favorable for large hail. However, storm coverage appears likely to be rather isolated at peak heating in the wake of the shortwave trough crossing the Dakotas. Greater confidence in storms exists early Friday morning ahead of the next upstream shortwave impulse. ...Eastern OH and PA vicinity... A low-amplitude upper trough from eastern Lake Superior to western OH will gradually move east with an attendant weak surface cyclone drifting across northern OH. Relatively cool temperatures aloft atop a plume of mid to upper 60s surface dew points should result in MLCAPE reaching 1500-2000 J/kg during the next few hours. Though low-level flow/shear will be weak, there will be sufficient deep-layer vertical shear for multiple mid-level rotating updrafts as scattered storms develop from the Upper OH Valley/Lower Great Lakes regions across the lee of the Appalachians. Convection should remain predominantly discrete, yielding a risk for both severe hail and damaging winds, with these threats waning after dusk. ..Grams/Gleason.. 08/15/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Thu Aug 15 2019 Valid 151630Z - 161200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS EASTERN KS... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF NORTHERN/CENTRAL GREAT PLAINS AND NORTHEAST STATES... ...SUMMARY... Severe thunderstorms are most likely to be centered on eastern Kansas during the late afternoon and evening. Severe hail and wind gusts may be significant with a few tornadoes also possible. ...Central/eastern KS vicinity... An MCS is ongoing across eastern NE with a trailing composite outflow/cold front extending into far northwest KS. Waning low-level warm advection through the next few hours should inhibit substantial strengthening across the Lower MS Valley. The trailing outflow will be the primary focus for late afternoon to early evening redevelopment. Low-level convergence should support initial storms from north-central into northeast KS. A plume of upper 60s surface dew points at present across central KS will be maintained as richer boundary-layer moisture advects north from OK, beneath the eastern extent of the elevated mixed layer. Ample diabatic heating will yield large buoyancy with MLCAPE likely reaching 2500-3500 J/kg. A veering wind profile with height will support initial supercells, with hodograph enlargement occurring through the evening as a southwesterly low-level jet intensifies. The setup should foster a risk for very large hail and a few tornadoes. However, the overall mode may tend to grow upscale into clusters and an MCS relatively quickly given the strengthening forcing for ascent during the evening. This may result in the predominant threat becoming severe wind gusts (a few of which may be significant) as an MCS develops bowing structures across eastern KS towards western MO/northern OK. Overall severe threat should subside overnight with the most likely MCS track approaching the Ozark Plateau. 12Z non-HRRR HREF members are more consistent with this overall scenario than recent HRRR runs, with the parent RAP maintaining more pronounced MLCIN in much of the warm sector. Nevertheless, an Enhanced Slight Risk appears warranted given the potential for a higher-end intensity/coverage scenario. ...SD vicinity... A low-amplitude shortwave trough and attendant surface boundary will move east across the Dakotas. Ample diabatic heating is underway downstream across central to eastern SD north of the NE MCS. Presence of upper 50s to low 60s boundary-layer dew points will support MLCAPE of at least 1500-2000 J/kg. While low-level shear will be weak, robust speed shear from 700 mb on up will foster an elongated mid/upper-level hodograph favorable for mid-level rotation and an eventual eastward-progressing MCS with potential for a brief bow. Initial large hail transitioning to predominant severe wind gusts should be the main threats before activity weakens in western MN. ...Eastern WY and NE Panhandle... Residual low-level moisture (corridor of upper 50s surface dew points) within a weak upslope regime north of the trailing composite outflow/cold front over northeast CO will support a conditional supercell environment favorable for large hail. However, storm coverage appears likely to be rather isolated at peak heating in the wake of the shortwave trough crossing the Dakotas. Greater confidence in storms exists early Friday morning ahead of the next upstream shortwave impulse. ...Eastern OH and PA vicinity... A low-amplitude upper trough from eastern Lake Superior to western OH will gradually move east with an attendant weak surface cyclone drifting across northern OH. Relatively cool temperatures aloft atop a plume of mid to upper 60s surface dew points should result in MLCAPE reaching 1500-2000 J/kg during the next few hours. Though low-level flow/shear will be weak, there will be sufficient deep-layer vertical shear for multiple mid-level rotating updrafts as scattered storms develop from the Upper OH Valley/Lower Great Lakes regions across the lee of the Appalachians. Convection should remain predominantly discrete, yielding a risk for both severe hail and damaging winds, with these threats waning after dusk. ..Grams/Gleason.. 08/15/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Thu Aug 15 2019 Valid 151630Z - 161200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS EASTERN KS... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF NORTHERN/CENTRAL GREAT PLAINS AND NORTHEAST STATES... ...SUMMARY... Severe thunderstorms are most likely to be centered on eastern Kansas during the late afternoon and evening. Severe hail and wind gusts may be significant with a few tornadoes also possible. ...Central/eastern KS vicinity... An MCS is ongoing across eastern NE with a trailing composite outflow/cold front extending into far northwest KS. Waning low-level warm advection through the next few hours should inhibit substantial strengthening across the Lower MS Valley. The trailing outflow will be the primary focus for late afternoon to early evening redevelopment. Low-level convergence should support initial storms from north-central into northeast KS. A plume of upper 60s surface dew points at present across central KS will be maintained as richer boundary-layer moisture advects north from OK, beneath the eastern extent of the elevated mixed layer. Ample diabatic heating will yield large buoyancy with MLCAPE likely reaching 2500-3500 J/kg. A veering wind profile with height will support initial supercells, with hodograph enlargement occurring through the evening as a southwesterly low-level jet intensifies. The setup should foster a risk for very large hail and a few tornadoes. However, the overall mode may tend to grow upscale into clusters and an MCS relatively quickly given the strengthening forcing for ascent during the evening. This may result in the predominant threat becoming severe wind gusts (a few of which may be significant) as an MCS develops bowing structures across eastern KS towards western MO/northern OK. Overall severe threat should subside overnight with the most likely MCS track approaching the Ozark Plateau. 12Z non-HRRR HREF members are more consistent with this overall scenario than recent HRRR runs, with the parent RAP maintaining more pronounced MLCIN in much of the warm sector. Nevertheless, an Enhanced Slight Risk appears warranted given the potential for a higher-end intensity/coverage scenario. ...SD vicinity... A low-amplitude shortwave trough and attendant surface boundary will move east across the Dakotas. Ample diabatic heating is underway downstream across central to eastern SD north of the NE MCS. Presence of upper 50s to low 60s boundary-layer dew points will support MLCAPE of at least 1500-2000 J/kg. While low-level shear will be weak, robust speed shear from 700 mb on up will foster an elongated mid/upper-level hodograph favorable for mid-level rotation and an eventual eastward-progressing MCS with potential for a brief bow. Initial large hail transitioning to predominant severe wind gusts should be the main threats before activity weakens in western MN. ...Eastern WY and NE Panhandle... Residual low-level moisture (corridor of upper 50s surface dew points) within a weak upslope regime north of the trailing composite outflow/cold front over northeast CO will support a conditional supercell environment favorable for large hail. However, storm coverage appears likely to be rather isolated at peak heating in the wake of the shortwave trough crossing the Dakotas. Greater confidence in storms exists early Friday morning ahead of the next upstream shortwave impulse. ...Eastern OH and PA vicinity... A low-amplitude upper trough from eastern Lake Superior to western OH will gradually move east with an attendant weak surface cyclone drifting across northern OH. Relatively cool temperatures aloft atop a plume of mid to upper 60s surface dew points should result in MLCAPE reaching 1500-2000 J/kg during the next few hours. Though low-level flow/shear will be weak, there will be sufficient deep-layer vertical shear for multiple mid-level rotating updrafts as scattered storms develop from the Upper OH Valley/Lower Great Lakes regions across the lee of the Appalachians. Convection should remain predominantly discrete, yielding a risk for both severe hail and damaging winds, with these threats waning after dusk. ..Grams/Gleason.. 08/15/2019 Read more

MD 1743 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF SOUTHEAST NE...NORTHEAST KS AND FAR NORTHWEST MO
Mesoscale Discussion 1743 NWS Storm Prediction Center Norman OK 1111 AM CDT Thu Aug 15 2019 Areas affected...portions of southeast NE...northeast KS and far northwest MO Concerning...Severe potential...Watch unlikely Valid 151611Z - 151815Z Probability of Watch Issuance...20 percent SUMMARY...Sporadic strong gusts are possible with east/southeastward progressing band of storms through early afternoon. DISCUSSION...An MCS over southeast NE will continue to track east/southeast at around 35-40 kt over the next few hours. After initial weakening earlier in the morning, this system appears to be maintaining current intensity with some periodic increases in strength. The most recent measured wind gust with the system was 47 mph at KHSI at 1451Z. The expectation is that the line segment will continue east/southeast along/just north of instability gradient oriented across central/eastern KS. The overnight southwesterly low level jet should continue to weaken through midday, and downstream anvil debris will inhibit stronger destabilization. The exception may be along the southern fringes of the MCS where cloud cover is thinner, and where any renewed convection will be closer to the moist axis and increasing instability. As low level lapse rates steepen to the south across KS, some intermittent strong gusts are possible. However, overall severe threat is expected to remain limited as the bulk of this system remains north and east of a more favorable severe environment. A watch is not expected at this time, but trends will continue to be monitored. ..Leitman/Grams.. 08/15/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...EAX...OAX...TOP...GID... LAT...LON 40479790 40819753 40709630 40429500 40139454 39719432 39159429 38939435 38849471 39019568 39279674 39569797 39829854 40029851 40359804 40479790 Read more

No Mesoscale Discussions are in effect as of Thu Aug 15 13:54:03 UTC 2019.

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0750 AM CDT Thu Aug 15 2019 Valid 151300Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO TONIGHT FROM PARTS OF KS TO SD AND WY... ...SUMMARY... Scattered severe storms are expected across parts of the central Plains through tonight. Large to very large hail and severe gusts are forecast with the stronger storms. ...KS to SD and WY through tonight... A thunderstorm cluster in central NE has been maintained this morning by warm advection on the nose of a 30-40 kt low-level jet and frontogenesis in the 850-700 mb layer. This convection will likely persist into early afternoon while moving southeastward into southeast NE/northeast KS. Convective evolution thereafter is somewhat in question, with the possibility of the storms weakening, or for additional development by mid afternoon along the southwest flank of the outflow across central KS. The latter scenario would continuously reinforce the cold pool and shunt the severe hail/wind threat to the south. If the convection weakens across northeast KS by mid afternoon, there will be potential for redevelopment on the edge of the modifying cold pool by this evening. The potential for supercells with very large hail and a tornado or two will depend heavily on the MCS weakening by early afternoon, and then the cold pool having several hours to modify by this evening such that surface-based storms can form along the edge of the remnant cold pool, where low-level shear will be strongest. The MCS should stabilize central NE enough to lower the severe threat through the afternoon/evening. Outflow will reinforce a baroclinic zone and upslope flow into WY this afternoon, though the boundary layer will likely remain relatively cool/capped. Late this evening, isolated storms may form in upslope flow regime, in an environment conditionally favorable for supercells with large hail. Farther north in SD, some moistening and surface heating west-northwest of the morning convection could result in sufficient destabilization for a few severe storms this afternoon. The focus for thunderstorm development will be a weak surface trough in advance of a midlevel shortwave trough moving east-southeastward from MT. Assuming MLCAPE can increase to 1500+ J/kg this afternoon, deep-layer shear will be sufficient for organized/supercell storms capable of producing large hail and damaging winds from about 20-00z. ...OH/PA area this afternoon/evening... A series of low-amplitude speed maxima aloft will progress eastward this afternoon from roughly northern IN to western PA. Similar to the previous two days farther west, surface heating within a residual moist boundary layer and a weak surface low/trough, plus lake-enhanced boundaries, will help focus thunderstorm development this afternoon from eastern OH/WV into central PA and far western NY. Though low-level flow/shear will be weak, there will be sufficient deep-layer vertical shear for a low-end supercell threat, based on moderate buoyancy (MLCAPE near 1500 J/kg). A few damaging winds and isolated large hail will be the main threats. ..Thompson/Kerr.. 08/15/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0750 AM CDT Thu Aug 15 2019 Valid 151300Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO TONIGHT FROM PARTS OF KS TO SD AND WY... ...SUMMARY... Scattered severe storms are expected across parts of the central Plains through tonight. Large to very large hail and severe gusts are forecast with the stronger storms. ...KS to SD and WY through tonight... A thunderstorm cluster in central NE has been maintained this morning by warm advection on the nose of a 30-40 kt low-level jet and frontogenesis in the 850-700 mb layer. This convection will likely persist into early afternoon while moving southeastward into southeast NE/northeast KS. Convective evolution thereafter is somewhat in question, with the possibility of the storms weakening, or for additional development by mid afternoon along the southwest flank of the outflow across central KS. The latter scenario would continuously reinforce the cold pool and shunt the severe hail/wind threat to the south. If the convection weakens across northeast KS by mid afternoon, there will be potential for redevelopment on the edge of the modifying cold pool by this evening. The potential for supercells with very large hail and a tornado or two will depend heavily on the MCS weakening by early afternoon, and then the cold pool having several hours to modify by this evening such that surface-based storms can form along the edge of the remnant cold pool, where low-level shear will be strongest. The MCS should stabilize central NE enough to lower the severe threat through the afternoon/evening. Outflow will reinforce a baroclinic zone and upslope flow into WY this afternoon, though the boundary layer will likely remain relatively cool/capped. Late this evening, isolated storms may form in upslope flow regime, in an environment conditionally favorable for supercells with large hail. Farther north in SD, some moistening and surface heating west-northwest of the morning convection could result in sufficient destabilization for a few severe storms this afternoon. The focus for thunderstorm development will be a weak surface trough in advance of a midlevel shortwave trough moving east-southeastward from MT. Assuming MLCAPE can increase to 1500+ J/kg this afternoon, deep-layer shear will be sufficient for organized/supercell storms capable of producing large hail and damaging winds from about 20-00z. ...OH/PA area this afternoon/evening... A series of low-amplitude speed maxima aloft will progress eastward this afternoon from roughly northern IN to western PA. Similar to the previous two days farther west, surface heating within a residual moist boundary layer and a weak surface low/trough, plus lake-enhanced boundaries, will help focus thunderstorm development this afternoon from eastern OH/WV into central PA and far western NY. Though low-level flow/shear will be weak, there will be sufficient deep-layer vertical shear for a low-end supercell threat, based on moderate buoyancy (MLCAPE near 1500 J/kg). A few damaging winds and isolated large hail will be the main threats. ..Thompson/Kerr.. 08/15/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0750 AM CDT Thu Aug 15 2019 Valid 151300Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO TONIGHT FROM PARTS OF KS TO SD AND WY... ...SUMMARY... Scattered severe storms are expected across parts of the central Plains through tonight. Large to very large hail and severe gusts are forecast with the stronger storms. ...KS to SD and WY through tonight... A thunderstorm cluster in central NE has been maintained this morning by warm advection on the nose of a 30-40 kt low-level jet and frontogenesis in the 850-700 mb layer. This convection will likely persist into early afternoon while moving southeastward into southeast NE/northeast KS. Convective evolution thereafter is somewhat in question, with the possibility of the storms weakening, or for additional development by mid afternoon along the southwest flank of the outflow across central KS. The latter scenario would continuously reinforce the cold pool and shunt the severe hail/wind threat to the south. If the convection weakens across northeast KS by mid afternoon, there will be potential for redevelopment on the edge of the modifying cold pool by this evening. The potential for supercells with very large hail and a tornado or two will depend heavily on the MCS weakening by early afternoon, and then the cold pool having several hours to modify by this evening such that surface-based storms can form along the edge of the remnant cold pool, where low-level shear will be strongest. The MCS should stabilize central NE enough to lower the severe threat through the afternoon/evening. Outflow will reinforce a baroclinic zone and upslope flow into WY this afternoon, though the boundary layer will likely remain relatively cool/capped. Late this evening, isolated storms may form in upslope flow regime, in an environment conditionally favorable for supercells with large hail. Farther north in SD, some moistening and surface heating west-northwest of the morning convection could result in sufficient destabilization for a few severe storms this afternoon. The focus for thunderstorm development will be a weak surface trough in advance of a midlevel shortwave trough moving east-southeastward from MT. Assuming MLCAPE can increase to 1500+ J/kg this afternoon, deep-layer shear will be sufficient for organized/supercell storms capable of producing large hail and damaging winds from about 20-00z. ...OH/PA area this afternoon/evening... A series of low-amplitude speed maxima aloft will progress eastward this afternoon from roughly northern IN to western PA. Similar to the previous two days farther west, surface heating within a residual moist boundary layer and a weak surface low/trough, plus lake-enhanced boundaries, will help focus thunderstorm development this afternoon from eastern OH/WV into central PA and far western NY. Though low-level flow/shear will be weak, there will be sufficient deep-layer vertical shear for a low-end supercell threat, based on moderate buoyancy (MLCAPE near 1500 J/kg). A few damaging winds and isolated large hail will be the main threats. ..Thompson/Kerr.. 08/15/2019 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0347 AM CDT Thu Aug 15 2019 Valid 181200Z - 231200Z ...DISCUSSION... On Sun/D4, an upper trough will lift north out of the Upper MS Valley and into Ontario, with rising heights across the central states. As such, little large-scale support will be available to focus severe storms, although isolated storms are possible across parts of the central Plains where instability will be large. By Mon/D5, an upper high will build over the southern High Plains, with zonal flow along the northern tier of states. Nocturnal storms are possible across the upper MS Valley late Monday in a warm advection regime. While areas of damaging wind cannot be ruled out with an MCS, predictability is low. The upper high will remain in place or retrograde slightly through the remainder of the period, and southerly winds across the Plains will maintain a somewhat moist, unstable air mass. However, predictability for any minor disturbance within the northwest flow that may focus storms across the northern Plains is low. Read more