SPC MD 1746

5 years 11 months ago
MD 1746 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF SOUTHEAST WY INTO THE NE PANHANDLE
Mesoscale Discussion 1746 NWS Storm Prediction Center Norman OK 0255 PM CDT Thu Aug 15 2019 Areas affected...parts of southeast WY into the NE Panhandle Concerning...Severe potential...Watch unlikely Valid 151955Z - 152130Z Probability of Watch Issuance...5 percent SUMMARY...Isolated strong to severe storms could produce large hail and gusty winds into the evening hours. DISCUSSION...Isolated elevated storms have developed along a surface boundary this afternoon across east-central WY. Surface dewpoints in the 50s to near 60 F beneath steep midlevel lapse rates is resulting in around 500-1000 J/kg MLCAPE. While instability is modest, effective shear greater than 45 kt is supportive of at least briefly rotating updrafts/weak supercells. Overall longevity of strong/severe storms should be limited by modest instability and weak forcing for ascent further removed from the influence of the shortwave impulse ejecting across the Dakotas. Briefly intense, isolated cells could produce large hail and gusty winds into the evening as convection shifts southeast. A watch is not expected given the isolated nature of the threat. ..Leitman/Grams.. 08/15/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...CYS... LAT...LON 42950568 43010475 42780310 42430207 42150183 41810188 41640219 41650278 41880434 42270555 42510587 42720587 42950568 Read more

SPC Day 2 Fire Weather Outlook

5 years 11 months ago
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0228 PM CDT Thu Aug 15 2019 Valid 161200Z - 171200Z The elevated area was expanded eastward across south-central Wyoming, and southward to include more of east-central Utah and west-central Colorado, as more widespread elevated wind/RH conditions are expected in these regions based on latest model guidance. Otherwise, the previous forecast remains on track (please see below for more details). ..Squitieri.. 08/15/2019 .PREV DISCUSSION... /ISSUED 1249 AM CDT Thu Aug 15 2019/ ...Synopsis... Elevated fire weather conditions will once again develop across portions of the Intermountain West on D2/Fri. A belt of enhanced mid-level flow will sag southward across portions of Idaho, Wyoming, and northern Colorado as a broad mid-level trough amplifies across the Canadian Rockies. This broadly cyclonic flow pattern will extend eastward across the Plains and through the Great Lakes as well, while weak ridging persists across the southern tier of the CONUS. ...Southwestern Wyoming, northwestern Colorado, and northeastern Utah... Heating/insolation beneath the increasingly strong mid-level flow across the region will result in areas of 15-25 mph surface flow during the afternoon and evening hours. Meanwhile, much of the region has been precipitation free over the last 1-2 weeks except for in higher elevations. RH values will also fall to near critical thresholds in a few areas and fall to as low as 7-10% in northeastern Utah. Widespread elevated fire weather conditions are most likely within the delineated area, though locally elevated fire weather conditions will also extend southward across eastern Utah/western Colorado and also within the Snake River Plain in Idaho where dry fuels exist and local terrain enhancements increase wind speeds. Furthermore, locally critical conditions are likely especially across northeastern Utah and northwestern Colorado, and if models trend any stronger with wind speeds, critical upgrades will need to be introduced. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook

5 years 11 months ago
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0228 PM CDT Thu Aug 15 2019 Valid 161200Z - 171200Z The elevated area was expanded eastward across south-central Wyoming, and southward to include more of east-central Utah and west-central Colorado, as more widespread elevated wind/RH conditions are expected in these regions based on latest model guidance. Otherwise, the previous forecast remains on track (please see below for more details). ..Squitieri.. 08/15/2019 .PREV DISCUSSION... /ISSUED 1249 AM CDT Thu Aug 15 2019/ ...Synopsis... Elevated fire weather conditions will once again develop across portions of the Intermountain West on D2/Fri. A belt of enhanced mid-level flow will sag southward across portions of Idaho, Wyoming, and northern Colorado as a broad mid-level trough amplifies across the Canadian Rockies. This broadly cyclonic flow pattern will extend eastward across the Plains and through the Great Lakes as well, while weak ridging persists across the southern tier of the CONUS. ...Southwestern Wyoming, northwestern Colorado, and northeastern Utah... Heating/insolation beneath the increasingly strong mid-level flow across the region will result in areas of 15-25 mph surface flow during the afternoon and evening hours. Meanwhile, much of the region has been precipitation free over the last 1-2 weeks except for in higher elevations. RH values will also fall to near critical thresholds in a few areas and fall to as low as 7-10% in northeastern Utah. Widespread elevated fire weather conditions are most likely within the delineated area, though locally elevated fire weather conditions will also extend southward across eastern Utah/western Colorado and also within the Snake River Plain in Idaho where dry fuels exist and local terrain enhancements increase wind speeds. Furthermore, locally critical conditions are likely especially across northeastern Utah and northwestern Colorado, and if models trend any stronger with wind speeds, critical upgrades will need to be introduced. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook

5 years 11 months ago
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0228 PM CDT Thu Aug 15 2019 Valid 161200Z - 171200Z The elevated area was expanded eastward across south-central Wyoming, and southward to include more of east-central Utah and west-central Colorado, as more widespread elevated wind/RH conditions are expected in these regions based on latest model guidance. Otherwise, the previous forecast remains on track (please see below for more details). ..Squitieri.. 08/15/2019 .PREV DISCUSSION... /ISSUED 1249 AM CDT Thu Aug 15 2019/ ...Synopsis... Elevated fire weather conditions will once again develop across portions of the Intermountain West on D2/Fri. A belt of enhanced mid-level flow will sag southward across portions of Idaho, Wyoming, and northern Colorado as a broad mid-level trough amplifies across the Canadian Rockies. This broadly cyclonic flow pattern will extend eastward across the Plains and through the Great Lakes as well, while weak ridging persists across the southern tier of the CONUS. ...Southwestern Wyoming, northwestern Colorado, and northeastern Utah... Heating/insolation beneath the increasingly strong mid-level flow across the region will result in areas of 15-25 mph surface flow during the afternoon and evening hours. Meanwhile, much of the region has been precipitation free over the last 1-2 weeks except for in higher elevations. RH values will also fall to near critical thresholds in a few areas and fall to as low as 7-10% in northeastern Utah. Widespread elevated fire weather conditions are most likely within the delineated area, though locally elevated fire weather conditions will also extend southward across eastern Utah/western Colorado and also within the Snake River Plain in Idaho where dry fuels exist and local terrain enhancements increase wind speeds. Furthermore, locally critical conditions are likely especially across northeastern Utah and northwestern Colorado, and if models trend any stronger with wind speeds, critical upgrades will need to be introduced. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook

5 years 11 months ago
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0228 PM CDT Thu Aug 15 2019 Valid 161200Z - 171200Z The elevated area was expanded eastward across south-central Wyoming, and southward to include more of east-central Utah and west-central Colorado, as more widespread elevated wind/RH conditions are expected in these regions based on latest model guidance. Otherwise, the previous forecast remains on track (please see below for more details). ..Squitieri.. 08/15/2019 .PREV DISCUSSION... /ISSUED 1249 AM CDT Thu Aug 15 2019/ ...Synopsis... Elevated fire weather conditions will once again develop across portions of the Intermountain West on D2/Fri. A belt of enhanced mid-level flow will sag southward across portions of Idaho, Wyoming, and northern Colorado as a broad mid-level trough amplifies across the Canadian Rockies. This broadly cyclonic flow pattern will extend eastward across the Plains and through the Great Lakes as well, while weak ridging persists across the southern tier of the CONUS. ...Southwestern Wyoming, northwestern Colorado, and northeastern Utah... Heating/insolation beneath the increasingly strong mid-level flow across the region will result in areas of 15-25 mph surface flow during the afternoon and evening hours. Meanwhile, much of the region has been precipitation free over the last 1-2 weeks except for in higher elevations. RH values will also fall to near critical thresholds in a few areas and fall to as low as 7-10% in northeastern Utah. Widespread elevated fire weather conditions are most likely within the delineated area, though locally elevated fire weather conditions will also extend southward across eastern Utah/western Colorado and also within the Snake River Plain in Idaho where dry fuels exist and local terrain enhancements increase wind speeds. Furthermore, locally critical conditions are likely especially across northeastern Utah and northwestern Colorado, and if models trend any stronger with wind speeds, critical upgrades will need to be introduced. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC MD 1745

5 years 11 months ago
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 Aug 15, 2019 1730 UTC Day 2 Convective Outlook

5 years 11 months ago
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 Aug 15, 2019 1730 UTC Day 2 Convective Outlook

5 years 11 months ago
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 Aug 15, 2019 1730 UTC Day 2 Convective Outlook

5 years 11 months ago
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 Aug 15, 2019 1730 UTC Day 2 Convective Outlook

5 years 11 months ago
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 MD 1744

5 years 11 months ago
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

5 years 11 months ago
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

5 years 11 months ago
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

5 years 11 months ago
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

5 years 11 months ago
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 Aug 15, 2019 1630 UTC Day 1 Convective Outlook

5 years 11 months ago
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 Aug 15, 2019 1630 UTC Day 1 Convective Outlook

5 years 11 months ago
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 Aug 15, 2019 1630 UTC Day 1 Convective Outlook

5 years 11 months ago
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 Aug 15, 2019 1630 UTC Day 1 Convective Outlook

5 years 11 months ago
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
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