Severe Storms

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 PM CDT Fri Sep 20 2019 Valid 210100Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN PLAINS AND CENTRAL HIGH PLAINS... ...SUMMARY... Scattered severe storms capable of producing wind damage, isolated large hail and a couple tornadoes are possible this evening across parts of the northern Plains, with more isolated severe storms possible in parts of the southern High Plains. ...Northern Plains/Central High Plains... The latest water-vapor imagery shows an upper-level low over the northern Rockies with southwest mid-level flow over the northern Plains. A couple perturbations in the flow appear to be moving across the northern Plains. The first is located in central North Dakota where numerous thunderstorms are ongoing. The second is located in western Nebraska where scattered thunderstorms are ongoing. At the surface, a cold front is located from far northeastern Wyoming northeastward into central North Dakota. To the east of the front, a moderately to strongly unstable airmass is present. This is coincident with moderate deep-layer shear which will support a severe threat this evening. The mass of convection over east-central North Dakota is expected to organize into a nearly continuous line and move slowly east-northeastward. This line will likely be accompanied with wind damage and isolated large hail. More discrete cells should continue to develop to the east of this line across eastern North Dakota and northwestern Minnesota. The stronger cells within this cluster may obtain supercell characteristics and have isolated large hail, wind damage and a tornado or two...see MCD 1991. Further southwest across northwest Nebraska and central South Dakota, a low-level jet will strengthen this evening. In response, thunderstorm coverage should gradually increase as storms develop across southern and central South Dakota over the next few hours. The strengthening low-level jet will create long hodographs favorable for rotating storms. A few that become supercells will have potential to produce large hail and an isolated tornado threat. As storm coverage becomes more numerous late this evening, wind damage and hail should become the predominant severe threat. ...Southern Plains... The latest water-vapor imagery shows southwest mid-level flow over the southern Plains with a minor shortwave trough located over southern Oklahoma. Scattered thunderstorms are ongoing near the shortwave trough. Near the trough, the airmass is moderately unstable with 0-6 km shear in the 30 to 35 kt range. This should be enough for a marginal severe threat for another hour or two as a bowing line segment moves eastward across northwest Texas and far southern Oklahoma. Isolated damaging wind gusts and hail will be possible. ..Broyles.. 09/21/2019 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 PM CDT Fri Sep 20 2019 Valid 210100Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN PLAINS AND CENTRAL HIGH PLAINS... ...SUMMARY... Scattered severe storms capable of producing wind damage, isolated large hail and a couple tornadoes are possible this evening across parts of the northern Plains, with more isolated severe storms possible in parts of the southern High Plains. ...Northern Plains/Central High Plains... The latest water-vapor imagery shows an upper-level low over the northern Rockies with southwest mid-level flow over the northern Plains. A couple perturbations in the flow appear to be moving across the northern Plains. The first is located in central North Dakota where numerous thunderstorms are ongoing. The second is located in western Nebraska where scattered thunderstorms are ongoing. At the surface, a cold front is located from far northeastern Wyoming northeastward into central North Dakota. To the east of the front, a moderately to strongly unstable airmass is present. This is coincident with moderate deep-layer shear which will support a severe threat this evening. The mass of convection over east-central North Dakota is expected to organize into a nearly continuous line and move slowly east-northeastward. This line will likely be accompanied with wind damage and isolated large hail. More discrete cells should continue to develop to the east of this line across eastern North Dakota and northwestern Minnesota. The stronger cells within this cluster may obtain supercell characteristics and have isolated large hail, wind damage and a tornado or two...see MCD 1991. Further southwest across northwest Nebraska and central South Dakota, a low-level jet will strengthen this evening. In response, thunderstorm coverage should gradually increase as storms develop across southern and central South Dakota over the next few hours. The strengthening low-level jet will create long hodographs favorable for rotating storms. A few that become supercells will have potential to produce large hail and an isolated tornado threat. As storm coverage becomes more numerous late this evening, wind damage and hail should become the predominant severe threat. ...Southern Plains... The latest water-vapor imagery shows southwest mid-level flow over the southern Plains with a minor shortwave trough located over southern Oklahoma. Scattered thunderstorms are ongoing near the shortwave trough. Near the trough, the airmass is moderately unstable with 0-6 km shear in the 30 to 35 kt range. This should be enough for a marginal severe threat for another hour or two as a bowing line segment moves eastward across northwest Texas and far southern Oklahoma. Isolated damaging wind gusts and hail will be possible. ..Broyles.. 09/21/2019 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 PM CDT Fri Sep 20 2019 Valid 210100Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN PLAINS AND CENTRAL HIGH PLAINS... ...SUMMARY... Scattered severe storms capable of producing wind damage, isolated large hail and a couple tornadoes are possible this evening across parts of the northern Plains, with more isolated severe storms possible in parts of the southern High Plains. ...Northern Plains/Central High Plains... The latest water-vapor imagery shows an upper-level low over the northern Rockies with southwest mid-level flow over the northern Plains. A couple perturbations in the flow appear to be moving across the northern Plains. The first is located in central North Dakota where numerous thunderstorms are ongoing. The second is located in western Nebraska where scattered thunderstorms are ongoing. At the surface, a cold front is located from far northeastern Wyoming northeastward into central North Dakota. To the east of the front, a moderately to strongly unstable airmass is present. This is coincident with moderate deep-layer shear which will support a severe threat this evening. The mass of convection over east-central North Dakota is expected to organize into a nearly continuous line and move slowly east-northeastward. This line will likely be accompanied with wind damage and isolated large hail. More discrete cells should continue to develop to the east of this line across eastern North Dakota and northwestern Minnesota. The stronger cells within this cluster may obtain supercell characteristics and have isolated large hail, wind damage and a tornado or two...see MCD 1991. Further southwest across northwest Nebraska and central South Dakota, a low-level jet will strengthen this evening. In response, thunderstorm coverage should gradually increase as storms develop across southern and central South Dakota over the next few hours. The strengthening low-level jet will create long hodographs favorable for rotating storms. A few that become supercells will have potential to produce large hail and an isolated tornado threat. As storm coverage becomes more numerous late this evening, wind damage and hail should become the predominant severe threat. ...Southern Plains... The latest water-vapor imagery shows southwest mid-level flow over the southern Plains with a minor shortwave trough located over southern Oklahoma. Scattered thunderstorms are ongoing near the shortwave trough. Near the trough, the airmass is moderately unstable with 0-6 km shear in the 30 to 35 kt range. This should be enough for a marginal severe threat for another hour or two as a bowing line segment moves eastward across northwest Texas and far southern Oklahoma. Isolated damaging wind gusts and hail will be possible. ..Broyles.. 09/21/2019 Read more

MD 1992 CONCERNING SEVERE THUNDERSTORM WATCH 655... FOR FAR EASTERN WYOMING...THE NEBRASKA PANHANDLE...AND WESTERN SOUTH DAKOTA
Mesoscale Discussion 1992 NWS Storm Prediction Center Norman OK 0753 PM CDT Fri Sep 20 2019 Areas affected...far eastern Wyoming...the Nebraska Panhandle...and western South Dakota Concerning...Severe Thunderstorm Watch 655... Valid 210053Z - 210300Z The severe weather threat for Severe Thunderstorm Watch 655 continues. SUMMARY...Isolated severe risk persists across portions of WW 655. DISCUSSION...Latest radar loop shows isolated stronger cells occurring at this time across parts of eastern Wyoming and northern portions of the Nebraska Panhandle, moving toward southwestern South Dakota. The storms are ongoing near and ahead of the southeastward-moving cold front, within an amply unstable airmass, and may expand in coverage over the next couple of hours as a southerly low-level jet strengthens over the region. Along with ongoing risk for hail with a few of the strongest storm cores, damaging-wind potential may increase, if storms can organize/grow upscale in conjunction with the developing LLJ. ..Goss.. 09/21/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ABR...LBF...UNR...CYS... LAT...LON 41800484 42730448 44120471 44820314 45000215 44920081 44350038 42710078 41520267 41800484 Read more

WW 0654 Status Updates
STATUS REPORT ON WW 654 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 35 SW MBG TO 40 NE Y22 TO 45 WSW BIS TO 25 N BIS TO 50 NNE BIS TO 60 SW DVL TO 30 WNW DVL TO 65 N DVL. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1991 ..KARSTENS..09/21/19 ATTN...WFO...FGF...BIS...ABR... STATUS REPORT FOR WS 654 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NDC005-015-019-027-029-037-043-059-071-083-085-095-103-210140- ND . NORTH DAKOTA COUNTIES INCLUDED ARE BENSON BURLEIGH CAVALIER EDDY EMMONS GRANT KIDDER MORTON RAMSEY SHERIDAN SIOUX TOWNER WELLS SDC021-031-041-107-129-210140- SD . SOUTH DAKOTA COUNTIES INCLUDED ARE CAMPBELL CORSON DEWEY POTTER WALWORTH THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE Read more

WW 0656 Status Updates
STATUS FOR WATCH 0656 HAS NOT BEEN ISSUED YET Read more

WW 0655 Status Updates
STATUS REPORT ON WW 655 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..GOSS..09/20/19 ATTN...WFO...CYS...LBF...UNR...ABR... STATUS REPORT FOR WS 655 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NEC013-031-045-123-157-161-165-210040- NE . NEBRASKA COUNTIES INCLUDED ARE BOX BUTTE CHERRY DAWES MORRILL SCOTTS BLUFF SHERIDAN SIOUX SDC007-033-047-055-065-071-075-093-095-102-103-117-119-121-137- 210040- SD . SOUTH DAKOTA COUNTIES INCLUDED ARE BENNETT CUSTER FALL RIVER HAAKON HUGHES JACKSON JONES MEADE MELLETTE OGLALA LAKOTA PENNINGTON STANLEY SULLY TODD ZIEBACH WYC015-027-210040- WY Read more

MD 1990 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR EASTERN NEW MEXICO INTO THE TEXAS PANHANDLE
Mesoscale Discussion 1990 NWS Storm Prediction Center Norman OK 0608 PM CDT Fri Sep 20 2019 Areas affected...eastern New Mexico into the Texas Panhandle Concerning...Severe potential...Watch unlikely Valid 202308Z - 210115Z Probability of Watch Issuance...20 percent SUMMARY...Limited/local risk for hail/wind may spread east out of eastern New Mexico into the Texas Panhandle over the next few hours. WW issuance is not anticipated at this time. DISCUSSION...Latest visible imagery shows isolated thunderstorms developing over east-central and northeastern New Mexico, with another cluster of storms near the Texas Panhandle/New Mexico border. The strongest storm is indicated over southwestern Quay County, New Mexico, and appears to be occurring at the intersection of a dryline, and an outflow boundary associated with the aforementioned cluster of storms to the northeast of this cell near the Texas/New Mexico border. The initiation area is characterized by a relatively moist (low 60s dewpoints) boundary layer, which -- in conjunction with diurnal heating -- is yielding 500 to 1500 J/kg mixed-layer CAPE. Ascent across the region is potentially being aided by a weak/subtle vort max shifting northeastward across the area per WV imagery. While storms would otherwise be expected to diminish with the loss of diurnal heating early this evening, some CAM runs hint that storms may grow upscale into a small bowing cluster. Should this occur, severe risk could become locally enhanced -- but even so, the limited areal and temporal nature of the risk suggests that a WW will likely remain unnecessary. ..Goss/Edwards.. 09/20/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LUB...AMA...MAF...ABQ... LAT...LON 33210530 34000514 34650475 35160427 35410350 35940309 36400241 36120191 35180196 34240265 33200372 33080504 33210530 Read more

MD 1991 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR CENTRAL/EASTERN NORTH DAKOTA AND NORTHWEST MINNESOTA
Mesoscale Discussion 1991 NWS Storm Prediction Center Norman OK 0650 PM CDT Fri Sep 20 2019 Areas affected...Central/Eastern North Dakota and Northwest Minnesota Concerning...Severe potential...Watch likely Valid 202350Z - 210115Z Probability of Watch Issuance...80 percent SUMMARY...Ongoing clusters of severe storms will likely enter/continue downstream of WW 654. A new watch will likely be issued within the next 1-2 hours. DISCUSSION...Regional radar shows multiple clusters of storms throughout the warm sector over portions of central/eastern North Dakota. Convection that developed along/near a cold front within WW 654 has congealed into a north-south oriented line, with the strongest storms currently residing in northeastern North Dakota along/near a warm front. Other convection has freely developed within the warm sector across portions of southeastern North Dakota in response to a subtle mid-level short-wave trough in concert with synoptic-scale height falls. Although uncertainty exists in the short-term evolution of the ongoing convective clusters, it seems likely that upscale growth of storms over central North Dakota will continue and begin exiting WW 654 within the next 1-2 hours. Meanwhile, storms across southeast North Dakota should persist. Mesoanalysis over this region shows 3000 J/kg of MLCAPE amidst weak deep-layer shear. However, RAP soundings indicate the potential for an uptick in low-level shear, perhaps to 30-35 kt. Large hail and damaging wind gusts remain the primary threats with this activity. Thus, a new watch will likely be needed for areas downstream of WW 654. ..Karstens/Edwards.. 09/20/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MPX...FGF...ABR...BIS... LAT...LON 45999877 46450032 47850052 48839993 49029857 48929557 47899511 46629504 45959591 45999877 Read more

MD 1990 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR EASTERN NEW MEXICO INTO THE TEXAS PANHANDLE
Mesoscale Discussion 1990 NWS Storm Prediction Center Norman OK 0608 PM CDT Fri Sep 20 2019 Areas affected...eastern New Mexico into the Texas Panhandle Concerning...Severe potential...Watch unlikely Valid 202308Z - 210115Z Probability of Watch Issuance...20 percent SUMMARY...Limited/local risk for hail/wind may spread east out of eastern New Mexico into the Texas Panhandle over the next few hours. WW issuance is not anticipated at this time. DISCUSSION...Latest visible imagery shows isolated thunderstorms developing over east-central and northeastern New Mexico, with another cluster of storms near the Texas Panhandle/New Mexico border. The strongest storm is indicated over southwestern Quay County, New Mexico, and appears to be occurring at the intersection of a dryline, and an outflow boundary associated with the aforementioned cluster of storms to the northeast of this cell near the Texas/New Mexico border. The initiation area is characterized by a relatively moist (low 60s dewpoints) boundary layer, which -- in conjunction with diurnal heating -- is yielding 500 to 1500 J/kg mixed-layer CAPE. Ascent across the region is potentially being aided by a weak/subtle vort max shifting northeastward across the area per WV imagery. While storms would otherwise be expected to diminish with the loss of diurnal heating early this evening, some CAM runs hint that storms may grow upscale into a small bowing cluster. Should this occur, severe risk could become locally enhanced -- but even so, the limited areal and temporal nature of the risk suggests that a WW will likely remain unnecessary. ..Goss/Edwards.. 09/20/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LUB...AMA...MAF...ABQ... LAT...LON 33210530 34000514 34650475 35160427 35410350 35940309 36400241 36120191 35180196 34240265 33200372 33080504 33210530 Read more

WW 0654 Status Updates
STATUS REPORT ON WW 654 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 35 NW PIR TO 40 WNW MBG TO 40 NE Y22 TO 45 SSW N60 TO 10 SSW N60 TO 30 ESE MOT TO 80 NNW DVL. ..KARSTENS..09/20/19 ATTN...WFO...FGF...BIS...ABR... STATUS REPORT FOR WS 654 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NDC005-015-019-027-029-031-037-043-047-049-051-055-057-059-065- 069-071-079-083-085-093-095-103-202340- ND . NORTH DAKOTA COUNTIES INCLUDED ARE BENSON BURLEIGH CAVALIER EDDY EMMONS FOSTER GRANT KIDDER LOGAN MCHENRY MCINTOSH MCLEAN MERCER MORTON OLIVER PIERCE RAMSEY ROLETTE SHERIDAN SIOUX STUTSMAN TOWNER WELLS SDC021-031-041-107-129-202340- SD . SOUTH DAKOTA COUNTIES INCLUDED ARE CAMPBELL CORSON DEWEY POTTER WALWORTH Read more

WW 654 SEVERE TSTM ND SD 201850Z - 210300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 654 NWS Storm Prediction Center Norman OK 150 PM CDT Fri Sep 20 2019 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Central North Dakota North-Central South Dakota * Effective this Friday afternoon and evening from 150 PM until 1000 PM CDT. * Primary threats include... Scattered large hail likely with isolated very large hail events to 2.5 inches in diameter possible Scattered damaging wind gusts to 70 mph likely A tornado or two possible SUMMARY...Thunderstorms will intensify this afternoon over parts of the central Dakotas, with a few storms becoming severe. Large hail is the primary threat, with an increasing risk of damaging winds by early evening. An isolated tornado or two is also possible. The severe thunderstorm watch area is approximately along and 75 statute miles east and west of a line from 70 miles northeast of Minot ND to 25 miles south of Mobridge SD. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU4). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && AVIATION...A few severe thunderstorms with hail surface and aloft to 2.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 25030. ...Hart Read more

No Mesoscale Discussions are in effect as of Fri Sep 20 22:03:09 UTC 2019.

WW 0655 Status Updates
STATUS FOR WATCH 0655 HAS NOT BEEN ISSUED YET Read more

WW 0655 Status Updates
STATUS FOR WATCH 0655 HAS NOT BEEN ISSUED YET Read more

WW 655 SEVERE TSTM NE SD WY 202200Z - 210700Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 655 NWS Storm Prediction Center Norman OK 400 PM MDT Fri Sep 20 2019 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Northwestern Nebraska Central and southwestern South Dakota Extreme eastern Wyoming * Effective this Friday afternoon and Saturday morning from 400 PM until 100 AM MDT. * Primary threats include... Scattered large hail and isolated very large hail events to 2 inches in diameter possible Scattered damaging wind gusts to 70 mph possible A tornado or two possible SUMMARY...An isolated supercell is ongoing over extreme eastern Wyoming at issuance time, with additional convection expected to fill in and move across the watch area through the remainder of this evening on either side of a slow-moving front. Large hail and severe gusts are the main concerns, though a tornado cannot be ruled out this evening. The severe thunderstorm watch area is approximately along and 80 statute miles east and west of a line from Scottsbluff NE to 55 miles northwest of Pierre SD. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU5). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...CONTINUE...WW 654... AVIATION...A few severe thunderstorms with hail surface and aloft to 2 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 22030. ...Edwards Read more

WW 0654 Status Updates
STATUS REPORT ON WW 654 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 35 NW PIR TO 40 WNW MBG TO 40 NE Y22 TO 30 ENE DIK. ..KARSTENS..09/20/19 ATTN...WFO...FGF...BIS...ABR... STATUS REPORT FOR WS 654 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NDC005-009-015-019-027-029-031-037-043-047-049-051-055-057-059- 065-069-071-075-079-083-085-093-095-101-103-202240- ND . NORTH DAKOTA COUNTIES INCLUDED ARE BENSON BOTTINEAU BURLEIGH CAVALIER EDDY EMMONS FOSTER GRANT KIDDER LOGAN MCHENRY MCINTOSH MCLEAN MERCER MORTON OLIVER PIERCE RAMSEY RENVILLE ROLETTE SHERIDAN SIOUX STUTSMAN TOWNER WARD WELLS SDC021-031-041-107-129-202240- SD . SOUTH DAKOTA COUNTIES INCLUDED ARE CAMPBELL CORSON DEWEY POTTER WALWORTH Read more

WW 0654 Status Updates
STATUS REPORT ON WW 654 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..DIAL..09/20/19 ATTN...WFO...FGF...BIS...ABR... STATUS REPORT FOR WS 654 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NDC005-009-015-019-027-029-031-037-043-047-049-051-055-057-059- 065-069-071-075-079-083-085-093-095-101-103-202140- ND . NORTH DAKOTA COUNTIES INCLUDED ARE BENSON BOTTINEAU BURLEIGH CAVALIER EDDY EMMONS FOSTER GRANT KIDDER LOGAN MCHENRY MCINTOSH MCLEAN MERCER MORTON OLIVER PIERCE RAMSEY RENVILLE ROLETTE SHERIDAN SIOUX STUTSMAN TOWNER WARD WELLS SDC021-031-041-107-129-202140- SD . SOUTH DAKOTA COUNTIES INCLUDED ARE CAMPBELL CORSON DEWEY POTTER WALWORTH Read more

MD 1989 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR EASTERN WYOMING...NORTHWEST NEBRASKA AND WESTERN SOUTH DAKOTA
Mesoscale Discussion 1989 NWS Storm Prediction Center Norman OK 0307 PM CDT Fri Sep 20 2019 Areas affected...eastern Wyoming...northwest Nebraska and western South Dakota Concerning...Severe potential...Watch possible Valid 202007Z - 202200Z Probability of Watch Issuance...40 percent SUMMARY...Storms are expected to increase in coverage and intensity this afternoon into the evening, posing a risk for isolated large hail, damaging wind and a tornado or two. Depending on convective trends, a WW might be needed by 22Z. DISCUSSION...A couple of storms are in the process of developing over the higher terrain of southeast WY as well as farther north over the Black Hills of western SD. This regime is mostly post-frontal with a quasi-stationary or slow moving cold front from the western Dakotas into southeast WY where surface dewpoints are in the 50s and temperatures are rising through the 70s. Latest objective analysis show 500-1000 J/kg MLCAPE in the post-frontal regime with 1500-2000 j/kg farther east in warm sector. Storms are expected to increase in coverage from eastern WY into western SD and northwest NE as deeper forcing for ascent accompanying an upstream shortwave trough spreads east above the destabilizing boundary layer. Winds aloft will strengthen with approach of the shortwave trough, supporting 40-50 kt effective bulk shear and some supercell structures. Isolated large hail and damaging wind will be the main threats. A secondary branch of the low-level jet is forecast to increase this evening from western NE into western SD in response to the approaching upper trough. A small window might exist by early evening in this region for a couple of tornadoes, before the surface layer begins to decouple. ..Dial/Hart.. 09/20/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...UNR...CYS... LAT...LON 41720495 43370439 45040367 44840190 43720179 42030322 41720495 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0249 PM CDT Fri Sep 20 2019 Valid 202000Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING OVER PORTIONS OF THE NORTHERN PLAINS... ...SUMMARY... Scattered severe storms capable of producing wind damage, isolated large hail and a couple tornadoes are possible this afternoon and evening across the northern Plains, with more isolated severe storms possible in parts of the southern High Plains. ...Discussion... No change was made to the severe probabilities. The forecast appears on track. Minor changes were made to the 10-percent thunderstorm probability line across the central Great Lakes and the central FL Peninsula. ..Smith.. 09/20/2019 .PREV DISCUSSION... /ISSUED 1115 AM CDT Fri Sep 20 2019/ ...Northern and Central Plains... Morning water vapor loop shows a large upper trough over the western US, with southwesterly midlevel flow strengthening across the Rockies and High Plains. Several weak impulses are noted from CO northeastward into the Dakotas, with clusters of showers and thunderstorms occurring at this time. The timing and effects of this ongoing convection will result in a rather complex forecast for this afternoon and evening. Activity currently over the western Dakotas is expected to intensify later today as air mass destabilizes and winds aloft strengthen. Occasionally severe storms are expected to affect parts of central and northeast ND into central SD through the mid-late afternoon, with damaging winds, hail, and a couple of tornadoes possible. Later this afternoon, forcing associated with the a stronger shortwave trough will help to initiate thunderstorms from southern MT into eastern WY. These storms will be in a favorable environment for supercells early in the convective life cycle, capable of large hail and a couple of tornadoes. These storms will likely congeal and grow upscale during the evening as they track across parts of NE/SD with a continued threat of damaging winds and hail. ...Southern Plains... A weak remnant outflow boundary extends from near LBB into southern OK. Thunderstorms are expected to develop in vicinity of this boundary this afternoon in a moist and very unstable air mass. Deep-layer shear will be marginal for convective organization. However, convergence along the boundary coupled with slightly enhanced low-level shear may be sufficient for a few supercell storms capable of hail, damaging winds, and perhaps a tornado. Read more