Severe Storms

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0234 AM CDT Wed Aug 07 2019 Valid 091200Z - 101200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN AND CENTRAL PLAINS...AND ACROSS PARTS OF OR INTO SOUTHEAST WA AND NORTHWEST ID... ...SUMMARY... Strong to severe thunderstorms are possible across portions of the northern and central Plains Friday afternoon and evening. Additional strong storms are possible across parts of the Pacific Northwest. ...Northern and Central Plains... The upper ridge will meander eastward over the Plains on Friday. A couple of shortwave impulses will float through the ridge in northwesterly deep-layer flow. The first ejects eastward from the northern Rockies as an upstream upper trough begins to move inland over the Pacific Northwest. This impulse will aid in weak surface cyclogenesis over the western Dakotas. Strengthening low-level south/southeasterly flow will transport low to mid 60s surface dewpoints northwestward into far eastern MT/WY/CO and across parts of the Dakotas/NE/KS. Strong heating will lead to moderate/strong destabilization by early afternoon with steep midlevel lapse rates in place beneath the upper ridge. Forecast soundings suggest shear profiles capable of supporting rating updrafts and large hail will be possible with initial storms from eastern MT/WY toward western ND/SD. Some tornado threat cannot be ruled out in the vicinity of the surface low where backed low level flow will maximize SRH coincident with mean mixing ratios approaching 14 g/kg. A 40 kt south/southwesterly low level jet is then forecast to increase during the evening and overnight hours, which could lead to upscale growth and increase in damaging wind potential across parts of SD. Given several periods of convection in days leading up to Friday and model differences in exact location of surface features, will introduce Marginal severe probs at this time, though upgrades in subsequent outlooks are possible. Further south, convection will develop over the higher terrain in CO. As convection moves off of higher terrain, high-based cells could produce hail and possibly strong gusts. However, the threat appears more conditional southward across eastern CO into parts of southeast WY and NE where capping may be stronger. Additionally, forecast soundings show weak midlevel flow, which could hinder storm organization/longevity of intense updrafts. ...Pacific Northwest... Thunderstorms will develop during the afternoon ahead of an upper shortwave trough moving onshore and a surface cold front moving inland during the evening. Modest boundary layer moisture with dewpoints in the upper 40s to low 50s and strong heating will result in MLCAPE values as high as 1500 J/kg with inverted-v thermodynamic profiles beneath the cloud bases. Strong southwesterly deep layer flow and effective shear values greater than 40 kt will lead to fast moving storms capable of strong downburst winds. Additionally, steep midlevel lapse rates could result in marginally severe hail. ..Leitman.. 08/07/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0234 AM CDT Wed Aug 07 2019 Valid 091200Z - 101200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN AND CENTRAL PLAINS...AND ACROSS PARTS OF OR INTO SOUTHEAST WA AND NORTHWEST ID... ...SUMMARY... Strong to severe thunderstorms are possible across portions of the northern and central Plains Friday afternoon and evening. Additional strong storms are possible across parts of the Pacific Northwest. ...Northern and Central Plains... The upper ridge will meander eastward over the Plains on Friday. A couple of shortwave impulses will float through the ridge in northwesterly deep-layer flow. The first ejects eastward from the northern Rockies as an upstream upper trough begins to move inland over the Pacific Northwest. This impulse will aid in weak surface cyclogenesis over the western Dakotas. Strengthening low-level south/southeasterly flow will transport low to mid 60s surface dewpoints northwestward into far eastern MT/WY/CO and across parts of the Dakotas/NE/KS. Strong heating will lead to moderate/strong destabilization by early afternoon with steep midlevel lapse rates in place beneath the upper ridge. Forecast soundings suggest shear profiles capable of supporting rating updrafts and large hail will be possible with initial storms from eastern MT/WY toward western ND/SD. Some tornado threat cannot be ruled out in the vicinity of the surface low where backed low level flow will maximize SRH coincident with mean mixing ratios approaching 14 g/kg. A 40 kt south/southwesterly low level jet is then forecast to increase during the evening and overnight hours, which could lead to upscale growth and increase in damaging wind potential across parts of SD. Given several periods of convection in days leading up to Friday and model differences in exact location of surface features, will introduce Marginal severe probs at this time, though upgrades in subsequent outlooks are possible. Further south, convection will develop over the higher terrain in CO. As convection moves off of higher terrain, high-based cells could produce hail and possibly strong gusts. However, the threat appears more conditional southward across eastern CO into parts of southeast WY and NE where capping may be stronger. Additionally, forecast soundings show weak midlevel flow, which could hinder storm organization/longevity of intense updrafts. ...Pacific Northwest... Thunderstorms will develop during the afternoon ahead of an upper shortwave trough moving onshore and a surface cold front moving inland during the evening. Modest boundary layer moisture with dewpoints in the upper 40s to low 50s and strong heating will result in MLCAPE values as high as 1500 J/kg with inverted-v thermodynamic profiles beneath the cloud bases. Strong southwesterly deep layer flow and effective shear values greater than 40 kt will lead to fast moving storms capable of strong downburst winds. Additionally, steep midlevel lapse rates could result in marginally severe hail. ..Leitman.. 08/07/2019 Read more

MD 1659 CONCERNING SEVERE THUNDERSTORM WATCH 557... FOR PORTIONS OF CENTRAL AND SOUTHERN NE
Mesoscale Discussion 1659 NWS Storm Prediction Center Norman OK 0222 AM CDT Wed Aug 07 2019 Areas affected...portions of central and southern NE Concerning...Severe Thunderstorm Watch 557... Valid 070722Z - 070845Z The severe weather threat for Severe Thunderstorm Watch 557 continues. SUMMARY...At least isolated severe gust/hail potential may continue in remaining parts of the watch area past its original 8Z expiration, with some potential to spread south of I-80. As such, portions of the watch are being extended in both southward extent and time. Persistence southward into KS at severe levels appears less probable, given the weaker parameters in that region, but trends will be monitored. DISCUSSION...A persistent complex of strong-severe thunderstorms, with a couple of marginally severe measured gusts since 05Z, is undergoing a gradual evolution from forward-dominant propagational motion component to mixed forward/rear. This is occurring in a warm-advection and moisture-transport regime atop the cold pool, with a modest upstream LLJ -- manifest by 30-kt southwesterly 850-mb winds at the LNX and UEX radar sites. Surface mesoanalysis shows a quasistationary frontal zone from the GRI/HSI area southeastward across northeastern KS near FRI and TOP, with only minor movement at most being expected during the next several hours. Convection should continue to be maximized in the associated instability/buoyancy gradient, just over the cool side of the surface boundary, across portions of central/southern NE. Modified RAOBs and model soundings indicate a transition from around 2000- 2500 J/kg MLCAPE and MUCAPE on the warm side of the boundary, over central/south-central NE where surface dew points remain in the mid 60s to low 70s F, to less than 250 J/kg close to the Missouri River. However, continued severe-gust potential at the surface likely will be rendered isolated and episodic given the nocturnally stabilizing boundary layer with MLCINH in the 150-400 J/kg range. Ambient deep shear is strong, with 50-70-kt northwesterly effective-shear vectors common over the region, and some forward propagation with damaging- wind threat may persist with the leading convection toward the GRI/HSI/HJH areas. Hail potential will exist with the most intense trailing cells over the cold pool. ..Edwards.. 08/07/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...OAX...GID...LBF... LAT...LON 42219934 41889877 41419801 40939758 40459734 40149756 40139889 40649939 41429970 42059968 42219934 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CDT Wed Aug 07 2019 Valid 081200Z - 091200Z ...Synopsis... The upper ridge across the Southwest into the Intermountain West is expected to shift slowly eastward on Thursday, as a deep upper trough approaches the Pacific Coast. Gradually increasing moisture in advance of the upper trough will continue to support at least isolated thunderstorm activity across portions of the Great Basin and interior Northwest. ...Central/northern NV into the interior Northwest... Thunderstorm coverage will likely increase compared to D1/Wednesday across central/northern NV into the interior Northwest on Thursday, as moisture gradually increases and the deep upper trough impinges on the region. Given the presence of potentially scattered thunderstorms overlapping regions of receptive fuels, lightning-related ignitions will again be possible, though there will also be greater potential for rainfall compared to D1/Wednesday. The greatest thunderstorm coverage is forecast to be over central/northern NV, but due to lingering uncertainty regarding convective evolution and potentially greater rainfall with any thunderstorm activity, the ISODRYT area is maintained in this outlook with no upgrade at this time. ..Dean.. 08/07/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CDT Wed Aug 07 2019 Valid 081200Z - 091200Z ...Synopsis... The upper ridge across the Southwest into the Intermountain West is expected to shift slowly eastward on Thursday, as a deep upper trough approaches the Pacific Coast. Gradually increasing moisture in advance of the upper trough will continue to support at least isolated thunderstorm activity across portions of the Great Basin and interior Northwest. ...Central/northern NV into the interior Northwest... Thunderstorm coverage will likely increase compared to D1/Wednesday across central/northern NV into the interior Northwest on Thursday, as moisture gradually increases and the deep upper trough impinges on the region. Given the presence of potentially scattered thunderstorms overlapping regions of receptive fuels, lightning-related ignitions will again be possible, though there will also be greater potential for rainfall compared to D1/Wednesday. The greatest thunderstorm coverage is forecast to be over central/northern NV, but due to lingering uncertainty regarding convective evolution and potentially greater rainfall with any thunderstorm activity, the ISODRYT area is maintained in this outlook with no upgrade at this time. ..Dean.. 08/07/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CDT Wed Aug 07 2019 Valid 081200Z - 091200Z ...Synopsis... The upper ridge across the Southwest into the Intermountain West is expected to shift slowly eastward on Thursday, as a deep upper trough approaches the Pacific Coast. Gradually increasing moisture in advance of the upper trough will continue to support at least isolated thunderstorm activity across portions of the Great Basin and interior Northwest. ...Central/northern NV into the interior Northwest... Thunderstorm coverage will likely increase compared to D1/Wednesday across central/northern NV into the interior Northwest on Thursday, as moisture gradually increases and the deep upper trough impinges on the region. Given the presence of potentially scattered thunderstorms overlapping regions of receptive fuels, lightning-related ignitions will again be possible, though there will also be greater potential for rainfall compared to D1/Wednesday. The greatest thunderstorm coverage is forecast to be over central/northern NV, but due to lingering uncertainty regarding convective evolution and potentially greater rainfall with any thunderstorm activity, the ISODRYT area is maintained in this outlook with no upgrade at this time. ..Dean.. 08/07/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CDT Wed Aug 07 2019 Valid 081200Z - 091200Z ...Synopsis... The upper ridge across the Southwest into the Intermountain West is expected to shift slowly eastward on Thursday, as a deep upper trough approaches the Pacific Coast. Gradually increasing moisture in advance of the upper trough will continue to support at least isolated thunderstorm activity across portions of the Great Basin and interior Northwest. ...Central/northern NV into the interior Northwest... Thunderstorm coverage will likely increase compared to D1/Wednesday across central/northern NV into the interior Northwest on Thursday, as moisture gradually increases and the deep upper trough impinges on the region. Given the presence of potentially scattered thunderstorms overlapping regions of receptive fuels, lightning-related ignitions will again be possible, though there will also be greater potential for rainfall compared to D1/Wednesday. The greatest thunderstorm coverage is forecast to be over central/northern NV, but due to lingering uncertainty regarding convective evolution and potentially greater rainfall with any thunderstorm activity, the ISODRYT area is maintained in this outlook with no upgrade at this time. ..Dean.. 08/07/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CDT Wed Aug 07 2019 Valid 081200Z - 091200Z ...Synopsis... The upper ridge across the Southwest into the Intermountain West is expected to shift slowly eastward on Thursday, as a deep upper trough approaches the Pacific Coast. Gradually increasing moisture in advance of the upper trough will continue to support at least isolated thunderstorm activity across portions of the Great Basin and interior Northwest. ...Central/northern NV into the interior Northwest... Thunderstorm coverage will likely increase compared to D1/Wednesday across central/northern NV into the interior Northwest on Thursday, as moisture gradually increases and the deep upper trough impinges on the region. Given the presence of potentially scattered thunderstorms overlapping regions of receptive fuels, lightning-related ignitions will again be possible, though there will also be greater potential for rainfall compared to D1/Wednesday. The greatest thunderstorm coverage is forecast to be over central/northern NV, but due to lingering uncertainty regarding convective evolution and potentially greater rainfall with any thunderstorm activity, the ISODRYT area is maintained in this outlook with no upgrade at this time. ..Dean.. 08/07/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CDT Wed Aug 07 2019 Valid 071200Z - 081200Z ...CRITICAL FIRE WEATHER AREA FOR DRY THUNDERSTORMS ACROSS PORTIONS OF NORTHEAST OREGON... ...Synopsis... Some dampening of the persistent upper ridge over the Southwest and Great Basin is expected today, as the upper low off of the Pacific coast gradually shifts eastward and smaller-scale shortwave troughs move around the periphery of the ridge. Moisture will gradually increase into portions of the Great Basin, supporting a threat of isolated to widely scattered thunderstorms. ...Interior Northwest into northwest NV... At least isolated thunderstorm coverage is expected this afternoon into tonight across portions of the interior Northwest into northwest NV, with some potential for scattered coverage across portions of northeast OR and also across northwest NV. While some increase in moisture is forecast compared to Tuesday, substantial rainfall is generally not expected across the region, and thunderstorm activity will pose a risk of ignitions given the presence of receptive fuels. The greatest confidence in the development of scattered thunderstorms amidst dry fuels is over portions of northeast OR, where a scattered dry-thunderstorm delineation has been included. A separate area across northwest NV may require an upgrade in the Day 1 update if confidence increases in storm coverage across this region. ..Dean.. 08/07/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CDT Wed Aug 07 2019 Valid 071200Z - 081200Z ...CRITICAL FIRE WEATHER AREA FOR DRY THUNDERSTORMS ACROSS PORTIONS OF NORTHEAST OREGON... ...Synopsis... Some dampening of the persistent upper ridge over the Southwest and Great Basin is expected today, as the upper low off of the Pacific coast gradually shifts eastward and smaller-scale shortwave troughs move around the periphery of the ridge. Moisture will gradually increase into portions of the Great Basin, supporting a threat of isolated to widely scattered thunderstorms. ...Interior Northwest into northwest NV... At least isolated thunderstorm coverage is expected this afternoon into tonight across portions of the interior Northwest into northwest NV, with some potential for scattered coverage across portions of northeast OR and also across northwest NV. While some increase in moisture is forecast compared to Tuesday, substantial rainfall is generally not expected across the region, and thunderstorm activity will pose a risk of ignitions given the presence of receptive fuels. The greatest confidence in the development of scattered thunderstorms amidst dry fuels is over portions of northeast OR, where a scattered dry-thunderstorm delineation has been included. A separate area across northwest NV may require an upgrade in the Day 1 update if confidence increases in storm coverage across this region. ..Dean.. 08/07/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CDT Wed Aug 07 2019 Valid 071200Z - 081200Z ...CRITICAL FIRE WEATHER AREA FOR DRY THUNDERSTORMS ACROSS PORTIONS OF NORTHEAST OREGON... ...Synopsis... Some dampening of the persistent upper ridge over the Southwest and Great Basin is expected today, as the upper low off of the Pacific coast gradually shifts eastward and smaller-scale shortwave troughs move around the periphery of the ridge. Moisture will gradually increase into portions of the Great Basin, supporting a threat of isolated to widely scattered thunderstorms. ...Interior Northwest into northwest NV... At least isolated thunderstorm coverage is expected this afternoon into tonight across portions of the interior Northwest into northwest NV, with some potential for scattered coverage across portions of northeast OR and also across northwest NV. While some increase in moisture is forecast compared to Tuesday, substantial rainfall is generally not expected across the region, and thunderstorm activity will pose a risk of ignitions given the presence of receptive fuels. The greatest confidence in the development of scattered thunderstorms amidst dry fuels is over portions of northeast OR, where a scattered dry-thunderstorm delineation has been included. A separate area across northwest NV may require an upgrade in the Day 1 update if confidence increases in storm coverage across this region. ..Dean.. 08/07/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CDT Wed Aug 07 2019 Valid 071200Z - 081200Z ...CRITICAL FIRE WEATHER AREA FOR DRY THUNDERSTORMS ACROSS PORTIONS OF NORTHEAST OREGON... ...Synopsis... Some dampening of the persistent upper ridge over the Southwest and Great Basin is expected today, as the upper low off of the Pacific coast gradually shifts eastward and smaller-scale shortwave troughs move around the periphery of the ridge. Moisture will gradually increase into portions of the Great Basin, supporting a threat of isolated to widely scattered thunderstorms. ...Interior Northwest into northwest NV... At least isolated thunderstorm coverage is expected this afternoon into tonight across portions of the interior Northwest into northwest NV, with some potential for scattered coverage across portions of northeast OR and also across northwest NV. While some increase in moisture is forecast compared to Tuesday, substantial rainfall is generally not expected across the region, and thunderstorm activity will pose a risk of ignitions given the presence of receptive fuels. The greatest confidence in the development of scattered thunderstorms amidst dry fuels is over portions of northeast OR, where a scattered dry-thunderstorm delineation has been included. A separate area across northwest NV may require an upgrade in the Day 1 update if confidence increases in storm coverage across this region. ..Dean.. 08/07/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CDT Wed Aug 07 2019 Valid 071200Z - 081200Z ...CRITICAL FIRE WEATHER AREA FOR DRY THUNDERSTORMS ACROSS PORTIONS OF NORTHEAST OREGON... ...Synopsis... Some dampening of the persistent upper ridge over the Southwest and Great Basin is expected today, as the upper low off of the Pacific coast gradually shifts eastward and smaller-scale shortwave troughs move around the periphery of the ridge. Moisture will gradually increase into portions of the Great Basin, supporting a threat of isolated to widely scattered thunderstorms. ...Interior Northwest into northwest NV... At least isolated thunderstorm coverage is expected this afternoon into tonight across portions of the interior Northwest into northwest NV, with some potential for scattered coverage across portions of northeast OR and also across northwest NV. While some increase in moisture is forecast compared to Tuesday, substantial rainfall is generally not expected across the region, and thunderstorm activity will pose a risk of ignitions given the presence of receptive fuels. The greatest confidence in the development of scattered thunderstorms amidst dry fuels is over portions of northeast OR, where a scattered dry-thunderstorm delineation has been included. A separate area across northwest NV may require an upgrade in the Day 1 update if confidence increases in storm coverage across this region. ..Dean.. 08/07/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

WW 0557 Status Updates
STATUS REPORT ON WW 557 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 NNW ANW TO 20 NE ANW TO 25 NNW ONL TO 20 NNE ONL TO 45 W OFK TO 20 WNW OLU. ..EDWARDS..08/07/19 ATTN...WFO...OAX...LBF...GID...FSD...UNR... STATUS REPORT FOR WS 557 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NEC009-011-017-041-071-077-089-093-115-125-149-163-175-183- 070740- NE . NEBRASKA COUNTIES INCLUDED ARE BLAINE BOONE BROWN CUSTER GARFIELD GREELEY HOLT HOWARD LOUP NANCE ROCK SHERMAN VALLEY WHEELER THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 0557 Status Updates
STATUS REPORT ON WW 557 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 NNW ANW TO 20 NE ANW TO 25 NNW ONL TO 20 NNE ONL TO 45 W OFK TO 20 WNW OLU. ..EDWARDS..08/07/19 ATTN...WFO...OAX...LBF...GID...FSD...UNR... STATUS REPORT FOR WS 557 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NEC009-011-017-041-071-077-089-093-115-125-149-163-175-183- 070740- NE . NEBRASKA COUNTIES INCLUDED ARE BLAINE BOONE BROWN CUSTER GARFIELD GREELEY HOLT HOWARD LOUP NANCE ROCK SHERMAN VALLEY WHEELER THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 0557 Status Updates
STATUS REPORT ON WW 557 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 NNW ANW TO 20 NE ANW TO 25 NNW ONL TO 20 NNE ONL TO 45 W OFK TO 20 WNW OLU. ..EDWARDS..08/07/19 ATTN...WFO...OAX...LBF...GID...FSD...UNR... STATUS REPORT FOR WS 557 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NEC009-011-017-041-071-077-089-093-115-125-149-163-175-183- 070740- NE . NEBRASKA COUNTIES INCLUDED ARE BLAINE BOONE BROWN CUSTER GARFIELD GREELEY HOLT HOWARD LOUP NANCE ROCK SHERMAN VALLEY WHEELER THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 0557 Status Updates
STATUS REPORT ON WW 557 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 NNW ANW TO 20 NE ANW TO 25 NNW ONL TO 20 NNE ONL TO 45 W OFK TO 20 WNW OLU. ..EDWARDS..08/07/19 ATTN...WFO...OAX...LBF...GID...FSD...UNR... STATUS REPORT FOR WS 557 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NEC009-011-017-041-071-077-089-093-115-125-149-163-175-183- 070740- NE . NEBRASKA COUNTIES INCLUDED ARE BLAINE BOONE BROWN CUSTER GARFIELD GREELEY HOLT HOWARD LOUP NANCE ROCK SHERMAN VALLEY WHEELER THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 557 SEVERE TSTM NE SD 070120Z - 070800Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 557 NWS Storm Prediction Center Norman OK 820 PM CDT Tue Aug 6 2019 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Parts of north central and central Nebraska Parts of south central and southeast South Dakota * Effective this Tuesday night and Wednesday morning from 820 PM until 300 AM CDT. * Primary threats include... Scattered large hail and isolated very large hail events to 2 inches in diameter possible Isolated damaging wind gusts to 70 mph possible SUMMARY...Clusters of severe storms, including some supercells, will continue to spread south-southeastward from South Dakota into Nebraska overnight, with additional storm development also possible. The storm environment will favor large hail and damaging gusts as the primary severe threats through the early morning hours. The severe thunderstorm watch area is approximately along and 55 statute miles east and west of a line from 45 miles north of Chamberlain SD to 55 miles south southeast of Burwell NE. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU7). 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...WW 556... AVIATION...A few severe thunderstorms with hail surface and aloft to 2 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 32030. ...Thompson Read more

MD 1658 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF NORTHERN/CENTRAL AL AND NORTHEASTERN MS
Mesoscale Discussion 1658 NWS Storm Prediction Center Norman OK 0123 AM CDT Wed Aug 07 2019 Areas affected...portions of northern/central AL and northeastern MS Concerning...Severe potential...Watch unlikely Valid 070623Z - 070900Z Probability of Watch Issuance...20 percent SUMMARY...Isolated damaging gusts, some near severe limits, may occur with a southeastward-moving band of thunderstorms during the next few hours. A watch is not currently expected. DISCUSSION...A loosely organized, multicellular thunderstorm cluster was evident at 06Z crossing from southern TN into portions of northeastern MS and northern AL along an instability gradient. The thermodynamic environment was characterized by rich low-level moisture -- manifest in low/mid 70s F surface dew points, though modified 00Z BMX RAOB and RAP soundings indicate only about 1.3- 1.5-inch total PW thanks to a dry layer above the surface. Nocturnal stabilization, and the presence of that dry layer, has offsetting effects: 1. Rendering MUCAPE unrepresentative on the high side while minimizing MLCAPE, with the latter ranging from around 1000 J/kg in central MS to only around 250 J/kg in northeastern AL, and 2. Support evaporative cooling and downdraft acceleration in that layer just above the surface. It is uncertain how much such downward parcel acceleration can overcome a gradually cooling near-surface layer (with associated increase in static stability) to render severe wind at the surface, but damaging gusts cannot be ruled out in the most intense cores. Kinematically, low-level flow should remain very weak, with west-northwesterly to northwesterly 850-mb winds minimizing storm-relative flow in the inflow layer. Regardless, the forward-propagational component of convective motion should be sufficient to sustain some inflow for a few more hours, amidst about 30-40 kt ambient effective-shear magnitudes. While a severe (50+ kt) gust cannot be ruled out, the potential currently appears too isolated and marginal for a watch. ..Edwards/Broyles.. 08/07/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BMX...HUN...MEG...JAN... LAT...LON 34848893 34838883 34788818 34788747 34628674 33718643 33168655 32948804 33218903 34908918 34848893 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Wed Aug 07 2019 Valid 081200Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL IN INTO OH...THE NORTHERN WV PANHANDLE...WESTERN PA AND FAR WESTERN NY... ...SUMMARY... Strong to severe thunderstorms capable of large hail and locally damaging wind gusts are expected Thursday afternoon and evening across portions of the Midwest from Indiana to western Pennsylvania and far western New York. ...Ohio Valley/Lower Great Lakes Vicinity... An upper trough over the upper Great Lakes will pivot eastward across the Midwest on Thursday, spreading strong northwesterly deep-layer flow across the region. At the surface, west/southwesterly low-level winds will transport mid to upper 60s F dewpoints eastward across the Ohio Valley toward the lower Great Lakes ahead of a southeastward-advancing cold front. Strong heating in this corridor of richer boundary-layer moisture will result in moderate instability (1500-2500 J/kg MLCAPE) in the presence of 30-40 kt effective shear. Convection may be ongoing Thursday morning across southwest MI and should increase and intensify by early afternoon across OH/IN, shifting southeast toward western NY/PA through the afternoon/evening. Vertical shear will support sustained cells with rotating updrafts and perhaps even some supercell structures, and long, straight forecast hodographs indicate a threat for large hail. While midlevel lapse rates are modest (around 6.5 C/km), CAPE/shear parameters should compensate some and most intense cells will be capable of large hail. 0-3 km lapse rates are also modest, but relatively fast storm motion could result in locally strong wind gusts. The severe threat becomes more uncertain/conditional with westward extent into west-central IN and IL. While steeper lapse rates and stronger instability will be in place with similar shear profiles as those to the east, forecast soundings indicate this area may be under the influence of midlevel subsidence. This scenario would suppress convection across the area. However, if storms do develop further west, thermodynamic and kinematic parameters certainly would support a severe threat. ...Portions of the High Plains into KS/OK... The upper ridge will shift east on Thursday, becoming oriented over the northern High Plains southward to western TX during the second half of the period. This will keep the region on the southern fringes of stronger northwesterly deep-layer flow. At the surface, a warm front will stall near the OK/KS border and be a focus for potential heavy rain. Some severe threat could develop in the vicinity of the warm front, but several rounds of convection between now and then is resulting in too much uncertainty in evolution of the boundary layer across that area. What does seem more likely is at least a low-end severe threat across parts of the High Plains from northeast NM into eastern CO/WY, southwest SD and perhaps as far east as the NE Panhandle far western KS. Southeasterly upslope low-level flow will transport low 50s dewpoints westward along the I-25 corridor, with low to mid 60s further east. Strong heating will result in storm development over higher terrain by early afternoon. Midlevel flow will be somewhat weak, but effective shear greater than 40 kt and MLCAPE as high as 1500 J/kg should support sporadic strong cells capable of hail and perhaps locally damaging gusts during the afternoon and early evening. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% - Slight ..Leitman.. 08/07/2019 Read more