Severe Storms

WW 0555 Status Updates
STATUS REPORT ON WW 555 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 ESE VIH TO 20 SSW FAM TO 15 E CGI TO 20 ENE CGI TO 20 SE MDH TO 25 SSW EVV TO 45 W SDF. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1654 ..DEAN..08/06/19 ATTN...WFO...PAH...LSX...ILX...IND...LMK... STATUS REPORT FOR WS 555 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC003-069-087-127-151-153-181-070040- IL . ILLINOIS COUNTIES INCLUDED ARE ALEXANDER HARDIN JOHNSON MASSAC POPE PULASKI UNION INC123-147-173-070040- IN . INDIANA COUNTIES INCLUDED ARE PERRY SPENCER WARRICK KYC007-033-035-039-047-055-059-075-083-091-101-105-107-139-143- 145-149-157-177-183-219-221-225-233-070040- KY Read more

WW 555 SEVERE TSTM IL IN KY MO 061850Z - 070200Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 555 NWS Storm Prediction Center Norman OK 150 PM CDT Tue Aug 6 2019 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of southern Illinois southern Indiana western Kentucky southeast Missouri * Effective this Tuesday afternoon and evening from 150 PM until 900 PM CDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible Isolated large hail events to 1 inch in diameter possible SUMMARY...Scattered multicell storms will continue to intensify within a strongly unstable environment and become capable of producing isolated damaging wind and possibly some hail through early evening. The severe thunderstorm watch area is approximately along and 80 statute miles north and south of a line from 10 miles north northwest of Farmington MO to 30 miles east northeast of Evansville IN. 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. && AVIATION...A few severe thunderstorms with hail surface and aloft to 1 inch. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 29035. ...Dial Read more

MD 1654 CONCERNING SEVERE THUNDERSTORM WATCH 555... FOR SOUTHEAST MO...NORTHEAST AR...SOUTHERN IL...SOUTHWEST IN...WESTERN KY...WESTERN TN
Mesoscale Discussion 1654 NWS Storm Prediction Center Norman OK 0543 PM CDT Tue Aug 06 2019 Areas affected...Southeast MO...Northeast AR...Southern IL...Southwest IN...Western KY...Western TN Concerning...Severe Thunderstorm Watch 555... Valid 062243Z - 070015Z The severe weather threat for Severe Thunderstorm Watch 555 continues. SUMMARY...Threat for hail and locally damaging wind will spread southward with time into early evening. Some risk may extend south of WW 555, though new watch issuance is considered unlikely. DISCUSSION...Clusters of thunderstorms are ongoing across WW 555 as of 2230Z. Some storm consolidation has been noted across southeast IL/far southwest IN into western KY, while convection has been somewhat more discrete further west into southeast MO. Moderate-to-strong buoyancy (MLCAPE of 1500-3000 J/kg) is in place across the region, with effective shear of 30-40 kt across southeast MO and somewhat weaker shear (25-35 kt) further east per recent mesoanalyses. Where some upscale growth has occurred across the eastern portion of WW 555, damaging wind has likely become the primary risk, though instances of marginally severe hail will remain possible. Hail will continue to be a threat across the western portion of WW 555, where shear is somewhat stronger and a somewhat more discrete mode has been noted. Isolated damaging wind will also be threat in the western portion of the watch. With time, some threat for hail and damaging wind will likely spread southward out of WW 555 into portions of northeast AR and western TN. Due to uncertainty regarding the longevity of the severe threat, watch issuance in this area is currently unlikely, though watch potential will be reconsidered if there is an increase in convective organization this evening. ..Dean/Thompson.. 08/06/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LMK...OHX...PAH...MEG...LSX...LZK...SGF... LAT...LON 38289136 37589009 37348961 37328930 37758914 37848849 38078759 38148728 38048688 37858647 37458638 37008659 36698694 36248764 36068846 35908916 35878956 35839004 35949039 36249068 36769098 37329127 38139171 38289136 Read more

WW 0556 Status Updates
STATUS REPORT ON WW 556 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 W Y22 TO 30 NNW Y22 TO 45 ENE DIK TO 35 SSW N60 TO 30 SE N60 TO 45 ESE MOT. ..JEWELL..08/06/19 ATTN...WFO...BIS...ABR... STATUS REPORT FOR WS 556 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NDC001-015-021-029-031-037-041-043-045-047-051-059-065-083-085- 093-103-062340- ND . NORTH DAKOTA COUNTIES INCLUDED ARE ADAMS BURLEIGH DICKEY EMMONS FOSTER GRANT HETTINGER KIDDER LAMOURE LOGAN MCINTOSH MORTON OLIVER SHERIDAN SIOUX STUTSMAN WELLS SDC013-021-031-041-045-049-059-065-069-089-107-115-119-129- 062340- SD . SOUTH DAKOTA COUNTIES INCLUDED ARE BROWN CAMPBELL CORSON DEWEY EDMUNDS FAULK HAND HUGHES HYDE MCPHERSON POTTER SPINK SULLY WALWORTH Read more

WW 556 SEVERE TSTM ND SD 061950Z - 070400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 556 NWS Storm Prediction Center Norman OK 250 PM CDT Tue Aug 6 2019 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of central and southern North Dakota northern South Dakota * Effective this Tuesday afternoon and evening from 250 PM until 1100 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 possible A tornado or two possible SUMMARY...Severe storms are expected to increase in coverage this afternoon and continue into the evening. Initial primary threat will be supercells with large to very large hail and downburst winds, though a brief tornado cannot be ruled out. Threat will transition to damaging wind as storms develop southeast into South Dakota this evening. The severe thunderstorm watch area is approximately along and 85 statute miles east and west of a line from 15 miles east northeast of Garrison ND to 75 miles south southwest of Aberdeen SD. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU6). 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 555... 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 31035. ...Dial Read more

MD 1653 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR SOUTHEAST KANSAS INTO SOUTHWEST MISSOURI
Mesoscale Discussion 1653 NWS Storm Prediction Center Norman OK 0452 PM CDT Tue Aug 06 2019 Areas affected...southeast Kansas into southwest Missouri Concerning...Severe potential...Watch unlikely Valid 062152Z - 070015Z Probability of Watch Issuance...5 percent SUMMARY...Widely spaced storms are likely to continue for a few hours mainly from southern Kansas into southwest Missouri, and isolated severe wind gusts or marginal hail is possible. DISCUSSION...Strong instability has developed this afternoon near a weak wind shift extending from central KS into southern MO. The 18Z LMN sounding shows tall CAPE profiles with relatively cool temperatures in the upper levels, in addition to 40-60 kt northwest winds. The strongest instability stretches from southeast KS into southwest MO where dewpoints remain in the 70s F. Despite weak low-level winds, strong updrafts and at least modest deep-layer shear will likely allow for a few slow-moving cells to persist through early evening. Locally severe downbursts are possible, and marginal hail may occur as well. ..Jewell/Thompson.. 08/06/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LZK...SGF...EAX...TSA...TOP...ICT...OUN...DDC... LAT...LON 36749123 36509125 36279142 36159209 36259497 36939917 37279971 37729995 37969984 38179952 38339895 38449784 38379684 38249493 38159392 37939263 37479169 36749123 Read more

MD 1652 CONCERNING SEVERE THUNDERSTORM WATCH 555... FOR EAST CENTRAL AND SOUTHEAST MISSOURI...SOUTHERN ILLINOIS...SOUTHWESTERN INDIANA...AND WESTERN KENTUCKY
Mesoscale Discussion 1652 NWS Storm Prediction Center Norman OK 0347 PM CDT Tue Aug 06 2019 Areas affected...east central and southeast Missouri...southern Illinois...southwestern Indiana...and western Kentucky Concerning...Severe Thunderstorm Watch 555... Valid 062047Z - 062245Z The severe weather threat for Severe Thunderstorm Watch 555 continues. SUMMARY...Storms -- and attendant severe risk -- continue moving across WW 555. DISCUSSION...Latest radar loop shows isolated severe storms -- capable of producing locally damaging winds and hail -- moving south-southeastward across the mid Mississippi and lower Ohio Valleys -- in and near WW 555. At this time, the most intense storms are evolving over southeast Illinois, where a convective cluster appears to be evolving. Should this evolution continue, risk for damaging winds would likely increase. Elsewhere, more isolated severe risk persists, with additional clustering possible. Depending upon evolution of the convection over the next couple of hours, a southward expansion of the WW may be required. ..Goss.. 08/06/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LMK...OHX...IND...PAH...ILX...MEG...LSX...LZK... SGF... LAT...LON 39148709 38318660 36058645 35719044 37089104 38319141 38989126 39148709 Read more

WW 0555 Status Updates
STATUS REPORT ON WW 555 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..GOSS..08/06/19 ATTN...WFO...PAH...LSX...ILX...IND...LMK... STATUS REPORT FOR WS 555 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC003-005-025-027-033-047-049-051-055-059-065-069-077-079-081- 087-101-119-121-127-133-145-151-153-157-159-163-165-181-185-189- 191-193-199-062140- IL . ILLINOIS COUNTIES INCLUDED ARE ALEXANDER BOND CLAY CLINTON CRAWFORD EDWARDS EFFINGHAM FAYETTE FRANKLIN GALLATIN HAMILTON HARDIN JACKSON JASPER JEFFERSON JOHNSON LAWRENCE MADISON MARION MASSAC MONROE PERRY POPE PULASKI RANDOLPH RICHLAND ST. CLAIR SALINE UNION WABASH WASHINGTON WAYNE WHITE WILLIAMSON INC027-037-051-055-083-101-125-129-147-153-163-173-062140- IN . INDIANA COUNTIES INCLUDED ARE Read more

WW 0556 Status Updates
STATUS REPORT ON WW 556 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..BENTLEY..08/06/19 ATTN...WFO...BIS...ABR... STATUS REPORT FOR WS 556 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NDC001-015-021-025-029-031-037-041-043-045-047-051-055-057-059- 065-083-085-089-093-103-062140- ND . NORTH DAKOTA COUNTIES INCLUDED ARE ADAMS BURLEIGH DICKEY DUNN EMMONS FOSTER GRANT HETTINGER KIDDER LAMOURE LOGAN MCINTOSH MCLEAN MERCER MORTON OLIVER SHERIDAN SIOUX STARK STUTSMAN WELLS SDC013-021-031-041-045-049-059-065-069-089-107-115-119-129- 062140- SD . SOUTH DAKOTA COUNTIES INCLUDED ARE BROWN CAMPBELL CORSON DEWEY EDMUNDS FAULK HAND HUGHES HYDE MCPHERSON POTTER SPINK SULLY WALWORTH Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0312 PM CDT Tue Aug 06 2019 Valid 062000Z - 071200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SD AND FAR NORTHEASTERN NE... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE MID MS VALLEY... ...SUMMARY... Scattered severe thunderstorms are expected across the northern Plains late this afternoon and evening, particularly across parts of the central/eastern Dakotas and eastern Nebraska, where storms may become capable of producing very large hail and damaging wind gusts. Other storms with locally strong to severe wind gusts are expected over a portion of the mid Mississippi Valley region. ...20Z Update... Thunderstorms have recently developed across parts of western/central ND along and just ahead of a surface cold front. Current expectations are for this activity to spread southeastward into south-central ND and north-central SD through the remainder of the afternoon. Large hail will likely be the main threat initially with supercells, with some potential for greater than 2 inch in diameter hailstones with the most robust storms. Upscale growth into a southward-moving line segment still seems probable across SD this evening, with damaging winds perhaps becoming more likely. Based on where storms are initiating this afternoon, there is some concern that the corridor of greatest severe wind potential may extend farther west into central SD where the greatest instability is forecast to be present this evening. Have expanded the Slight Risk for hail into more of ND to account for observational trends, and the Enhanced Risk for severe winds has been expanded westward to include much of central SD. See Mesoscale Discussion 1651 for more information on the near-term severe threat across this region. The Marginal Risk has also been extended northwestward to include parts of northeastern MT. A storm or two may form in an area of low-level convergence across far southwestern Saskatchewan over the next couple of hours. Although low-level moisture remains limited across this region (surface dewpoints generally in the mid to upper 40s), strong northwesterly flow aloft should support updraft rotation with mainly an isolated hail risk. Minor adjustments have been made to the Slight Risk across southern IL and vicinity to include more of east-central/southeastern MO based on latest radar and observational trends. The Marginal Risk has also been trimmed across parts of the OH Valley to account for the latest surface cold front position. ..Gleason.. 08/06/2019 .PREV DISCUSSION... /ISSUED 1126 AM CDT Tue Aug 06 2019/ ...Northern and central Plains region... A corridor of richer low-level moisture with low 60s F dewpoints will advect northward into the northern Plains ahead of a southeast-advancing cold front and beneath a plume of steep mid-level lapse rates. With strong diabatic heating, these processes will result in moderate instability from southern ND through SD into NE with up to 2000-2500 J/kg MLCAPE expected. Most CAM solutions are similar with evolving scenario indicating storms will initiate over southern ND where the cold front intercepts the corridor of richer low-level moisture and where the cap should weaken sufficiently with deep boundary layer mixing by late this afternoon. A belt of stronger northwesterly mid-level winds will overspread this region contributing to 40-50 kt effective bulk shear. Supercells with the potential for very large hail will be the initial primary threat, though a brief tornado or two cannot be ruled out. Storms will eventually evolve into lines/clusters as they develop south, with primary threat transitioning to damaging wind into the evening. ...Lower Ohio Valley region... Strong diabatic heating of a moist boundary layer with low 70s F dewpoints will result in moderate to strong instability 2000-2500 J/kg MLCAPE in this region this afternoon. WV imagery shows a shortwave trough embedded within a northwesterly flow regime over IA moving southeast. At least modest forcing for ascent attending this feature and convergence along a front and pre-frontal trough should be sufficient to initiate storms from southern IL, southwest IN into western KY this afternoon. Northwesterly wind profiles with 30-35 kt above 700 mb and steepening low-level lapse rates should be sufficient for some storms to produce locally strong to damaging wind gusts through early or mid evening. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0312 PM CDT Tue Aug 06 2019 Valid 062000Z - 071200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SD AND FAR NORTHEASTERN NE... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE MID MS VALLEY... ...SUMMARY... Scattered severe thunderstorms are expected across the northern Plains late this afternoon and evening, particularly across parts of the central/eastern Dakotas and eastern Nebraska, where storms may become capable of producing very large hail and damaging wind gusts. Other storms with locally strong to severe wind gusts are expected over a portion of the mid Mississippi Valley region. ...20Z Update... Thunderstorms have recently developed across parts of western/central ND along and just ahead of a surface cold front. Current expectations are for this activity to spread southeastward into south-central ND and north-central SD through the remainder of the afternoon. Large hail will likely be the main threat initially with supercells, with some potential for greater than 2 inch in diameter hailstones with the most robust storms. Upscale growth into a southward-moving line segment still seems probable across SD this evening, with damaging winds perhaps becoming more likely. Based on where storms are initiating this afternoon, there is some concern that the corridor of greatest severe wind potential may extend farther west into central SD where the greatest instability is forecast to be present this evening. Have expanded the Slight Risk for hail into more of ND to account for observational trends, and the Enhanced Risk for severe winds has been expanded westward to include much of central SD. See Mesoscale Discussion 1651 for more information on the near-term severe threat across this region. The Marginal Risk has also been extended northwestward to include parts of northeastern MT. A storm or two may form in an area of low-level convergence across far southwestern Saskatchewan over the next couple of hours. Although low-level moisture remains limited across this region (surface dewpoints generally in the mid to upper 40s), strong northwesterly flow aloft should support updraft rotation with mainly an isolated hail risk. Minor adjustments have been made to the Slight Risk across southern IL and vicinity to include more of east-central/southeastern MO based on latest radar and observational trends. The Marginal Risk has also been trimmed across parts of the OH Valley to account for the latest surface cold front position. ..Gleason.. 08/06/2019 .PREV DISCUSSION... /ISSUED 1126 AM CDT Tue Aug 06 2019/ ...Northern and central Plains region... A corridor of richer low-level moisture with low 60s F dewpoints will advect northward into the northern Plains ahead of a southeast-advancing cold front and beneath a plume of steep mid-level lapse rates. With strong diabatic heating, these processes will result in moderate instability from southern ND through SD into NE with up to 2000-2500 J/kg MLCAPE expected. Most CAM solutions are similar with evolving scenario indicating storms will initiate over southern ND where the cold front intercepts the corridor of richer low-level moisture and where the cap should weaken sufficiently with deep boundary layer mixing by late this afternoon. A belt of stronger northwesterly mid-level winds will overspread this region contributing to 40-50 kt effective bulk shear. Supercells with the potential for very large hail will be the initial primary threat, though a brief tornado or two cannot be ruled out. Storms will eventually evolve into lines/clusters as they develop south, with primary threat transitioning to damaging wind into the evening. ...Lower Ohio Valley region... Strong diabatic heating of a moist boundary layer with low 70s F dewpoints will result in moderate to strong instability 2000-2500 J/kg MLCAPE in this region this afternoon. WV imagery shows a shortwave trough embedded within a northwesterly flow regime over IA moving southeast. At least modest forcing for ascent attending this feature and convergence along a front and pre-frontal trough should be sufficient to initiate storms from southern IL, southwest IN into western KY this afternoon. Northwesterly wind profiles with 30-35 kt above 700 mb and steepening low-level lapse rates should be sufficient for some storms to produce locally strong to damaging wind gusts through early or mid evening. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0312 PM CDT Tue Aug 06 2019 Valid 062000Z - 071200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SD AND FAR NORTHEASTERN NE... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE MID MS VALLEY... ...SUMMARY... Scattered severe thunderstorms are expected across the northern Plains late this afternoon and evening, particularly across parts of the central/eastern Dakotas and eastern Nebraska, where storms may become capable of producing very large hail and damaging wind gusts. Other storms with locally strong to severe wind gusts are expected over a portion of the mid Mississippi Valley region. ...20Z Update... Thunderstorms have recently developed across parts of western/central ND along and just ahead of a surface cold front. Current expectations are for this activity to spread southeastward into south-central ND and north-central SD through the remainder of the afternoon. Large hail will likely be the main threat initially with supercells, with some potential for greater than 2 inch in diameter hailstones with the most robust storms. Upscale growth into a southward-moving line segment still seems probable across SD this evening, with damaging winds perhaps becoming more likely. Based on where storms are initiating this afternoon, there is some concern that the corridor of greatest severe wind potential may extend farther west into central SD where the greatest instability is forecast to be present this evening. Have expanded the Slight Risk for hail into more of ND to account for observational trends, and the Enhanced Risk for severe winds has been expanded westward to include much of central SD. See Mesoscale Discussion 1651 for more information on the near-term severe threat across this region. The Marginal Risk has also been extended northwestward to include parts of northeastern MT. A storm or two may form in an area of low-level convergence across far southwestern Saskatchewan over the next couple of hours. Although low-level moisture remains limited across this region (surface dewpoints generally in the mid to upper 40s), strong northwesterly flow aloft should support updraft rotation with mainly an isolated hail risk. Minor adjustments have been made to the Slight Risk across southern IL and vicinity to include more of east-central/southeastern MO based on latest radar and observational trends. The Marginal Risk has also been trimmed across parts of the OH Valley to account for the latest surface cold front position. ..Gleason.. 08/06/2019 .PREV DISCUSSION... /ISSUED 1126 AM CDT Tue Aug 06 2019/ ...Northern and central Plains region... A corridor of richer low-level moisture with low 60s F dewpoints will advect northward into the northern Plains ahead of a southeast-advancing cold front and beneath a plume of steep mid-level lapse rates. With strong diabatic heating, these processes will result in moderate instability from southern ND through SD into NE with up to 2000-2500 J/kg MLCAPE expected. Most CAM solutions are similar with evolving scenario indicating storms will initiate over southern ND where the cold front intercepts the corridor of richer low-level moisture and where the cap should weaken sufficiently with deep boundary layer mixing by late this afternoon. A belt of stronger northwesterly mid-level winds will overspread this region contributing to 40-50 kt effective bulk shear. Supercells with the potential for very large hail will be the initial primary threat, though a brief tornado or two cannot be ruled out. Storms will eventually evolve into lines/clusters as they develop south, with primary threat transitioning to damaging wind into the evening. ...Lower Ohio Valley region... Strong diabatic heating of a moist boundary layer with low 70s F dewpoints will result in moderate to strong instability 2000-2500 J/kg MLCAPE in this region this afternoon. WV imagery shows a shortwave trough embedded within a northwesterly flow regime over IA moving southeast. At least modest forcing for ascent attending this feature and convergence along a front and pre-frontal trough should be sufficient to initiate storms from southern IL, southwest IN into western KY this afternoon. Northwesterly wind profiles with 30-35 kt above 700 mb and steepening low-level lapse rates should be sufficient for some storms to produce locally strong to damaging wind gusts through early or mid evening. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0312 PM CDT Tue Aug 06 2019 Valid 062000Z - 071200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SD AND FAR NORTHEASTERN NE... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE MID MS VALLEY... ...SUMMARY... Scattered severe thunderstorms are expected across the northern Plains late this afternoon and evening, particularly across parts of the central/eastern Dakotas and eastern Nebraska, where storms may become capable of producing very large hail and damaging wind gusts. Other storms with locally strong to severe wind gusts are expected over a portion of the mid Mississippi Valley region. ...20Z Update... Thunderstorms have recently developed across parts of western/central ND along and just ahead of a surface cold front. Current expectations are for this activity to spread southeastward into south-central ND and north-central SD through the remainder of the afternoon. Large hail will likely be the main threat initially with supercells, with some potential for greater than 2 inch in diameter hailstones with the most robust storms. Upscale growth into a southward-moving line segment still seems probable across SD this evening, with damaging winds perhaps becoming more likely. Based on where storms are initiating this afternoon, there is some concern that the corridor of greatest severe wind potential may extend farther west into central SD where the greatest instability is forecast to be present this evening. Have expanded the Slight Risk for hail into more of ND to account for observational trends, and the Enhanced Risk for severe winds has been expanded westward to include much of central SD. See Mesoscale Discussion 1651 for more information on the near-term severe threat across this region. The Marginal Risk has also been extended northwestward to include parts of northeastern MT. A storm or two may form in an area of low-level convergence across far southwestern Saskatchewan over the next couple of hours. Although low-level moisture remains limited across this region (surface dewpoints generally in the mid to upper 40s), strong northwesterly flow aloft should support updraft rotation with mainly an isolated hail risk. Minor adjustments have been made to the Slight Risk across southern IL and vicinity to include more of east-central/southeastern MO based on latest radar and observational trends. The Marginal Risk has also been trimmed across parts of the OH Valley to account for the latest surface cold front position. ..Gleason.. 08/06/2019 .PREV DISCUSSION... /ISSUED 1126 AM CDT Tue Aug 06 2019/ ...Northern and central Plains region... A corridor of richer low-level moisture with low 60s F dewpoints will advect northward into the northern Plains ahead of a southeast-advancing cold front and beneath a plume of steep mid-level lapse rates. With strong diabatic heating, these processes will result in moderate instability from southern ND through SD into NE with up to 2000-2500 J/kg MLCAPE expected. Most CAM solutions are similar with evolving scenario indicating storms will initiate over southern ND where the cold front intercepts the corridor of richer low-level moisture and where the cap should weaken sufficiently with deep boundary layer mixing by late this afternoon. A belt of stronger northwesterly mid-level winds will overspread this region contributing to 40-50 kt effective bulk shear. Supercells with the potential for very large hail will be the initial primary threat, though a brief tornado or two cannot be ruled out. Storms will eventually evolve into lines/clusters as they develop south, with primary threat transitioning to damaging wind into the evening. ...Lower Ohio Valley region... Strong diabatic heating of a moist boundary layer with low 70s F dewpoints will result in moderate to strong instability 2000-2500 J/kg MLCAPE in this region this afternoon. WV imagery shows a shortwave trough embedded within a northwesterly flow regime over IA moving southeast. At least modest forcing for ascent attending this feature and convergence along a front and pre-frontal trough should be sufficient to initiate storms from southern IL, southwest IN into western KY this afternoon. Northwesterly wind profiles with 30-35 kt above 700 mb and steepening low-level lapse rates should be sufficient for some storms to produce locally strong to damaging wind gusts through early or mid evening. Read more

WW 0556 Status Updates
STATUS FOR WATCH 0556 HAS NOT BEEN ISSUED YET Read more