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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Thu Aug 08 2019 Valid 091200Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN PLAINS AND OREGON... ...SUMMARY... Isolated severe thunderstorms will be possible across portions of the northern Plains as well as parts Oregon and vicinity, mainly Friday afternoon and evening. Large hail and damaging wind gusts should be the main threats, but a couple tornadoes may also occur across parts of western/central South Dakota. ...Northern/Central Plains... A shortwave trough will round an upper ridge centered over the Rockies and encourage thunderstorms to develop by Friday afternoon along a surface trough/front located across the northern High Plains. Some storms may be ongoing Friday morning, which could limit destabilization with northward extent into ND. Upper 60s to lower 70s surface dewpoints will combine with strong diurnal heating to result in around 1500-3000 J/kg of MLCAPE, with the greatest instability expected across western/central SD. A veering/strengthening wind profile will likely support 35-50 kt of effective bulk shear, with supercells expected initially. Isolated large hail will probably be the main threat with this initially discrete convection. Storms may potentially grow upscale into a MCS across central SD Friday evening as a southerly low-level jet strengthens. If this occurs, then severe winds would become the primary severe threat. Given the veering low-level wind profile, a couple tornadoes also cannot be ruled out late Friday afternoon/evening, mainly across parts of western/central SD. Farther south, shear is forecast to be weaker across the central High Plains, but isolated large hail and strong/gusty winds could occur with the strongest storms. ...Pacific Northwest... An upper low over the eastern Pacific will approach the OR/CA Coast by Friday evening, with mid-level southerly winds forecast to strengthen across much of OR in response. Low-level southerly flow should transport low to mid 50s surface dewpoints into western OR, with values generally decreasing into the mid/upper 40s along and east of the Cascade crest. Mid-level lapse rates should steepen across this region through the day, which combined with diurnal heating should support around 500-1250 J/kg of MLCAPE. As wind fields increase by mid afternoon, around 30-40 kt of effective bulk shear should also develop. A vorticity maximum embedded within the upper low will likely encourage convective initiation along and east the Cascades by early afternoon. Storms should subsequently spread north-northeastward into eastern OR and parts of southern WA. The forecast combination of instability and shear suggests updrafts will become organized, with both a isolated large hail and severe wind gust threat existing through Friday evening. ...Virginia/North Carolina... A belt of 30-40 kt westerly flow will likely remain over much of VA/NC through the period. At the surface, a stalled front should be located west/east from WV into northern/central VA and the Delmarva Peninsula Friday afternoon. Large-scale forcing for ascent may remain somewhat nebulous across this area, but some guidance does suggest isolated to scattered storm development may occur along the front in central VA and then spread southeastward Friday afternoon and evening. NAM/RAP forecast soundings across this region show around 1500-2000 J/kg of MLCAPE and 30-40 kt of effective bulk shear. Both multicells and marginal supercell structures will be possible. Isolated large hail may occur with semi-discrete convection initially, with a damaging wind threat potentially increasing if storms can form into a small southeastward-moving cluster. ...Ozarks into the Mid-South/Lower Mississippi Valley and Southeast... A couple of MCVs from prior convection will likely be located across these regions Friday morning. Diurnal heating of a very moist low-level airmass will result in moderate to strong instability developing along/south of a convectively reinforced surface boundary. Around 20-30 kt of mid-level west-northwesterly flow should overlie these areas. Some modest storm organization may be realized, with potential for clustering of storms as they move east-southeastward through early Friday evening. Strong/gusty downdraft winds producing isolated damage may occur. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% - Slight ..Gleason.. 08/08/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Thu Aug 08 2019 Valid 091200Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN PLAINS AND OREGON... ...SUMMARY... Isolated severe thunderstorms will be possible across portions of the northern Plains as well as parts Oregon and vicinity, mainly Friday afternoon and evening. Large hail and damaging wind gusts should be the main threats, but a couple tornadoes may also occur across parts of western/central South Dakota. ...Northern/Central Plains... A shortwave trough will round an upper ridge centered over the Rockies and encourage thunderstorms to develop by Friday afternoon along a surface trough/front located across the northern High Plains. Some storms may be ongoing Friday morning, which could limit destabilization with northward extent into ND. Upper 60s to lower 70s surface dewpoints will combine with strong diurnal heating to result in around 1500-3000 J/kg of MLCAPE, with the greatest instability expected across western/central SD. A veering/strengthening wind profile will likely support 35-50 kt of effective bulk shear, with supercells expected initially. Isolated large hail will probably be the main threat with this initially discrete convection. Storms may potentially grow upscale into a MCS across central SD Friday evening as a southerly low-level jet strengthens. If this occurs, then severe winds would become the primary severe threat. Given the veering low-level wind profile, a couple tornadoes also cannot be ruled out late Friday afternoon/evening, mainly across parts of western/central SD. Farther south, shear is forecast to be weaker across the central High Plains, but isolated large hail and strong/gusty winds could occur with the strongest storms. ...Pacific Northwest... An upper low over the eastern Pacific will approach the OR/CA Coast by Friday evening, with mid-level southerly winds forecast to strengthen across much of OR in response. Low-level southerly flow should transport low to mid 50s surface dewpoints into western OR, with values generally decreasing into the mid/upper 40s along and east of the Cascade crest. Mid-level lapse rates should steepen across this region through the day, which combined with diurnal heating should support around 500-1250 J/kg of MLCAPE. As wind fields increase by mid afternoon, around 30-40 kt of effective bulk shear should also develop. A vorticity maximum embedded within the upper low will likely encourage convective initiation along and east the Cascades by early afternoon. Storms should subsequently spread north-northeastward into eastern OR and parts of southern WA. The forecast combination of instability and shear suggests updrafts will become organized, with both a isolated large hail and severe wind gust threat existing through Friday evening. ...Virginia/North Carolina... A belt of 30-40 kt westerly flow will likely remain over much of VA/NC through the period. At the surface, a stalled front should be located west/east from WV into northern/central VA and the Delmarva Peninsula Friday afternoon. Large-scale forcing for ascent may remain somewhat nebulous across this area, but some guidance does suggest isolated to scattered storm development may occur along the front in central VA and then spread southeastward Friday afternoon and evening. NAM/RAP forecast soundings across this region show around 1500-2000 J/kg of MLCAPE and 30-40 kt of effective bulk shear. Both multicells and marginal supercell structures will be possible. Isolated large hail may occur with semi-discrete convection initially, with a damaging wind threat potentially increasing if storms can form into a small southeastward-moving cluster. ...Ozarks into the Mid-South/Lower Mississippi Valley and Southeast... A couple of MCVs from prior convection will likely be located across these regions Friday morning. Diurnal heating of a very moist low-level airmass will result in moderate to strong instability developing along/south of a convectively reinforced surface boundary. Around 20-30 kt of mid-level west-northwesterly flow should overlie these areas. Some modest storm organization may be realized, with potential for clustering of storms as they move east-southeastward through early Friday evening. Strong/gusty downdraft winds producing isolated damage may occur. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% - Slight ..Gleason.. 08/08/2019 Read more

WW 0562 Status Updates
STATUS FOR WATCH 0562 HAS NOT BEEN ISSUED YET Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1121 AM CDT Thu Aug 08 2019 Valid 081630Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF PA/NY/OH/WV... ...SUMMARY... The greatest concentration of potentially severe storms today is expected across the lower Great Lakes and northern/central Appalachians to the mid/upper Ohio Valley. ...Synopsis... A large trough will continue moving across eastern Canada and the eastern U.S. today, with another large trough surrounding a very slow-moving upper low over the eastern Pacific. In between, ridging will continue to prevail over the Rockies and south-central U.S. through tonight. At the surface, a weak pressure field prevails. A subtle cool front will continue crossing the lower Great Lakes/Ohio Valley today, while remnants of a prior/weak front linger from the southeastern U.S. west-northwestward into the Oklahoma vicinity. These two boundaries, and weak disturbances aloft crossing the Great Basin area ahead of the Pacific low/trough, will support showers and thunderstorm activity, along with limited/local severe risk. ...NY/PA/OH/WV vicinity... Showers and thunderstorms are ongoing across western New York and adjacent northwest Pennsylvania, near a very weak cool front moving across the region. As heating continues into the afternoon, resulting in additional/modest destabilization, an increase in convective coverage is expected, along with some uptick in intensity -- aided by moderate westerly/west-northwesterly flow through a deep layer. With this flow promoting rather quick eastward storm motion, stronger convective elements will be capable of producing gusty/damaging winds, that may reach severe levels locally. Risk should continue through the afternoon, diminishing with the onset of diurnal cooling early this evening. For additional short-term information, please refer to SWOMCD #1674. ...Southern KS/OK east-southeast to northern MS... A large area of weak convection is ongoing from the southern Plains, east across the Ozarks to the northern Mississippi Vicinity. An outflow boundary is observed from Oklahoma southeast to northern Mississippi, on the southern fringe of a stronger west-northwest to east-southeast band of storms. Some intensification of storms within this band, and/or new convective development near the aforementioned outflow, may -- given the favorably moist/gradually destabilizing airmass away from active convection -- intensify to occasionally severe levels. Gusty/locally damaging winds may occur with the strongest storms, along with some risk for large hail. Storms -- and possibly some severe risk -- will continue into the overnight hours, as a south-southwesterly low-level jet develops across the southern Plains, aiding continued storm development/sustenance. ...Central and southern high Plains... Daytime heating of a seasonally moist boundary layer across the high Plains region will permit afternoon destabilization, supporting development of scattered to isolated thunderstorms. Mid-level flow is not particularly strong across the region (generally 20 to 30 kt from the west), a weak easterly component to the low-level flow will help to provide both ample shear for a few organized storms, as well as some tendency for storms to progress southeastward off the higher terrain. The strongest storms/storm clusters may be capable of producing gusty/damaging winds, along with some hail risk. Severe risk should gradually decrease through the evening, as convection weakens. ...Parts of the Great Basin and vicinity... A relatively moist low-level airmass resides across the Great Basin vicinity, with dewpoints in the low 50s. Showers and isolated thunderstorms are ongoing across parts of the region -- partly in response to several disturbances aloft moving across the area, embedded within cyclonic upper flow surrounding the eastern Pacific upper low. Clearing is noted in morning visible imagery across parts of Nevada away from ongoing convection, which will aid in afternoon destabilization, and an associated increase in convective coverage. Given moderate deep-layer southwesterly flow supporting semi-organized cells/clusters, potential for locally damaging winds will exist with a few of the strongest storms, before convection weakens this evening. ..Goss.. 08/08/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1121 AM CDT Thu Aug 08 2019 Valid 081630Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF PA/NY/OH/WV... ...SUMMARY... The greatest concentration of potentially severe storms today is expected across the lower Great Lakes and northern/central Appalachians to the mid/upper Ohio Valley. ...Synopsis... A large trough will continue moving across eastern Canada and the eastern U.S. today, with another large trough surrounding a very slow-moving upper low over the eastern Pacific. In between, ridging will continue to prevail over the Rockies and south-central U.S. through tonight. At the surface, a weak pressure field prevails. A subtle cool front will continue crossing the lower Great Lakes/Ohio Valley today, while remnants of a prior/weak front linger from the southeastern U.S. west-northwestward into the Oklahoma vicinity. These two boundaries, and weak disturbances aloft crossing the Great Basin area ahead of the Pacific low/trough, will support showers and thunderstorm activity, along with limited/local severe risk. ...NY/PA/OH/WV vicinity... Showers and thunderstorms are ongoing across western New York and adjacent northwest Pennsylvania, near a very weak cool front moving across the region. As heating continues into the afternoon, resulting in additional/modest destabilization, an increase in convective coverage is expected, along with some uptick in intensity -- aided by moderate westerly/west-northwesterly flow through a deep layer. With this flow promoting rather quick eastward storm motion, stronger convective elements will be capable of producing gusty/damaging winds, that may reach severe levels locally. Risk should continue through the afternoon, diminishing with the onset of diurnal cooling early this evening. For additional short-term information, please refer to SWOMCD #1674. ...Southern KS/OK east-southeast to northern MS... A large area of weak convection is ongoing from the southern Plains, east across the Ozarks to the northern Mississippi Vicinity. An outflow boundary is observed from Oklahoma southeast to northern Mississippi, on the southern fringe of a stronger west-northwest to east-southeast band of storms. Some intensification of storms within this band, and/or new convective development near the aforementioned outflow, may -- given the favorably moist/gradually destabilizing airmass away from active convection -- intensify to occasionally severe levels. Gusty/locally damaging winds may occur with the strongest storms, along with some risk for large hail. Storms -- and possibly some severe risk -- will continue into the overnight hours, as a south-southwesterly low-level jet develops across the southern Plains, aiding continued storm development/sustenance. ...Central and southern high Plains... Daytime heating of a seasonally moist boundary layer across the high Plains region will permit afternoon destabilization, supporting development of scattered to isolated thunderstorms. Mid-level flow is not particularly strong across the region (generally 20 to 30 kt from the west), a weak easterly component to the low-level flow will help to provide both ample shear for a few organized storms, as well as some tendency for storms to progress southeastward off the higher terrain. The strongest storms/storm clusters may be capable of producing gusty/damaging winds, along with some hail risk. Severe risk should gradually decrease through the evening, as convection weakens. ...Parts of the Great Basin and vicinity... A relatively moist low-level airmass resides across the Great Basin vicinity, with dewpoints in the low 50s. Showers and isolated thunderstorms are ongoing across parts of the region -- partly in response to several disturbances aloft moving across the area, embedded within cyclonic upper flow surrounding the eastern Pacific upper low. Clearing is noted in morning visible imagery across parts of Nevada away from ongoing convection, which will aid in afternoon destabilization, and an associated increase in convective coverage. Given moderate deep-layer southwesterly flow supporting semi-organized cells/clusters, potential for locally damaging winds will exist with a few of the strongest storms, before convection weakens this evening. ..Goss.. 08/08/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1121 AM CDT Thu Aug 08 2019 Valid 081630Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF PA/NY/OH/WV... ...SUMMARY... The greatest concentration of potentially severe storms today is expected across the lower Great Lakes and northern/central Appalachians to the mid/upper Ohio Valley. ...Synopsis... A large trough will continue moving across eastern Canada and the eastern U.S. today, with another large trough surrounding a very slow-moving upper low over the eastern Pacific. In between, ridging will continue to prevail over the Rockies and south-central U.S. through tonight. At the surface, a weak pressure field prevails. A subtle cool front will continue crossing the lower Great Lakes/Ohio Valley today, while remnants of a prior/weak front linger from the southeastern U.S. west-northwestward into the Oklahoma vicinity. These two boundaries, and weak disturbances aloft crossing the Great Basin area ahead of the Pacific low/trough, will support showers and thunderstorm activity, along with limited/local severe risk. ...NY/PA/OH/WV vicinity... Showers and thunderstorms are ongoing across western New York and adjacent northwest Pennsylvania, near a very weak cool front moving across the region. As heating continues into the afternoon, resulting in additional/modest destabilization, an increase in convective coverage is expected, along with some uptick in intensity -- aided by moderate westerly/west-northwesterly flow through a deep layer. With this flow promoting rather quick eastward storm motion, stronger convective elements will be capable of producing gusty/damaging winds, that may reach severe levels locally. Risk should continue through the afternoon, diminishing with the onset of diurnal cooling early this evening. For additional short-term information, please refer to SWOMCD #1674. ...Southern KS/OK east-southeast to northern MS... A large area of weak convection is ongoing from the southern Plains, east across the Ozarks to the northern Mississippi Vicinity. An outflow boundary is observed from Oklahoma southeast to northern Mississippi, on the southern fringe of a stronger west-northwest to east-southeast band of storms. Some intensification of storms within this band, and/or new convective development near the aforementioned outflow, may -- given the favorably moist/gradually destabilizing airmass away from active convection -- intensify to occasionally severe levels. Gusty/locally damaging winds may occur with the strongest storms, along with some risk for large hail. Storms -- and possibly some severe risk -- will continue into the overnight hours, as a south-southwesterly low-level jet develops across the southern Plains, aiding continued storm development/sustenance. ...Central and southern high Plains... Daytime heating of a seasonally moist boundary layer across the high Plains region will permit afternoon destabilization, supporting development of scattered to isolated thunderstorms. Mid-level flow is not particularly strong across the region (generally 20 to 30 kt from the west), a weak easterly component to the low-level flow will help to provide both ample shear for a few organized storms, as well as some tendency for storms to progress southeastward off the higher terrain. The strongest storms/storm clusters may be capable of producing gusty/damaging winds, along with some hail risk. Severe risk should gradually decrease through the evening, as convection weakens. ...Parts of the Great Basin and vicinity... A relatively moist low-level airmass resides across the Great Basin vicinity, with dewpoints in the low 50s. Showers and isolated thunderstorms are ongoing across parts of the region -- partly in response to several disturbances aloft moving across the area, embedded within cyclonic upper flow surrounding the eastern Pacific upper low. Clearing is noted in morning visible imagery across parts of Nevada away from ongoing convection, which will aid in afternoon destabilization, and an associated increase in convective coverage. Given moderate deep-layer southwesterly flow supporting semi-organized cells/clusters, potential for locally damaging winds will exist with a few of the strongest storms, before convection weakens this evening. ..Goss.. 08/08/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1121 AM CDT Thu Aug 08 2019 Valid 081630Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF PA/NY/OH/WV... ...SUMMARY... The greatest concentration of potentially severe storms today is expected across the lower Great Lakes and northern/central Appalachians to the mid/upper Ohio Valley. ...Synopsis... A large trough will continue moving across eastern Canada and the eastern U.S. today, with another large trough surrounding a very slow-moving upper low over the eastern Pacific. In between, ridging will continue to prevail over the Rockies and south-central U.S. through tonight. At the surface, a weak pressure field prevails. A subtle cool front will continue crossing the lower Great Lakes/Ohio Valley today, while remnants of a prior/weak front linger from the southeastern U.S. west-northwestward into the Oklahoma vicinity. These two boundaries, and weak disturbances aloft crossing the Great Basin area ahead of the Pacific low/trough, will support showers and thunderstorm activity, along with limited/local severe risk. ...NY/PA/OH/WV vicinity... Showers and thunderstorms are ongoing across western New York and adjacent northwest Pennsylvania, near a very weak cool front moving across the region. As heating continues into the afternoon, resulting in additional/modest destabilization, an increase in convective coverage is expected, along with some uptick in intensity -- aided by moderate westerly/west-northwesterly flow through a deep layer. With this flow promoting rather quick eastward storm motion, stronger convective elements will be capable of producing gusty/damaging winds, that may reach severe levels locally. Risk should continue through the afternoon, diminishing with the onset of diurnal cooling early this evening. For additional short-term information, please refer to SWOMCD #1674. ...Southern KS/OK east-southeast to northern MS... A large area of weak convection is ongoing from the southern Plains, east across the Ozarks to the northern Mississippi Vicinity. An outflow boundary is observed from Oklahoma southeast to northern Mississippi, on the southern fringe of a stronger west-northwest to east-southeast band of storms. Some intensification of storms within this band, and/or new convective development near the aforementioned outflow, may -- given the favorably moist/gradually destabilizing airmass away from active convection -- intensify to occasionally severe levels. Gusty/locally damaging winds may occur with the strongest storms, along with some risk for large hail. Storms -- and possibly some severe risk -- will continue into the overnight hours, as a south-southwesterly low-level jet develops across the southern Plains, aiding continued storm development/sustenance. ...Central and southern high Plains... Daytime heating of a seasonally moist boundary layer across the high Plains region will permit afternoon destabilization, supporting development of scattered to isolated thunderstorms. Mid-level flow is not particularly strong across the region (generally 20 to 30 kt from the west), a weak easterly component to the low-level flow will help to provide both ample shear for a few organized storms, as well as some tendency for storms to progress southeastward off the higher terrain. The strongest storms/storm clusters may be capable of producing gusty/damaging winds, along with some hail risk. Severe risk should gradually decrease through the evening, as convection weakens. ...Parts of the Great Basin and vicinity... A relatively moist low-level airmass resides across the Great Basin vicinity, with dewpoints in the low 50s. Showers and isolated thunderstorms are ongoing across parts of the region -- partly in response to several disturbances aloft moving across the area, embedded within cyclonic upper flow surrounding the eastern Pacific upper low. Clearing is noted in morning visible imagery across parts of Nevada away from ongoing convection, which will aid in afternoon destabilization, and an associated increase in convective coverage. Given moderate deep-layer southwesterly flow supporting semi-organized cells/clusters, potential for locally damaging winds will exist with a few of the strongest storms, before convection weakens this evening. ..Goss.. 08/08/2019 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1059 AM CDT Thu Aug 08 2019 Valid 081700Z - 091200Z The forecast remains on track. Minor modifications have been made to the ISODRYT area based on latest observations and model guidance. Two shortwave troughs are evident in satellite water vapor imagery in northern Nevada and near the southern California coast. These features are already promoting thunderstorm activity and are expected to continue doing so into the afternoon/evening. Thunderstorm coverage may approach 40% within portions of Oregon, but GPS satellite and forecast soundings show increasing PWAT values which will help to mitigate some of the threat for ignitions. ..Wendt.. 08/08/2019 .PREV DISCUSSION... /ISSUED 0110 AM CDT Thu Aug 08 2019/ ...Synopsis... Deep southerly flow between a longwave trough over the northeastern Pacific and a longwave ridge centered over the Great Basin will maintain mid-level moisture in a corridor from Nevada northward to northern Washington State today. Heating beneath this moist plume will promote areas of isolated to scattered thunderstorms, which will serve as the main focus for fire weather threats across the West. ...Nevada, Idaho, southwestern Montana, central and eastern Oregon, and central and eastern Washington State... The aforementioned synoptic pattern and surface heating will foster development and gradual expansion of convective coverage - likely beginning around mid-morning across Nevada and expanding northward through the afternoon and evening. These storms will occur atop widespread areas of dry fuels, favoring lightning-related fire ignition and spread. Additionally, gusty/erratic downburst winds will complicate fire suppression efforts near ongoing fires in the region. The greatest coverage of storms is expected to occur across portions of Nevada during the afternoon, where 40%+ coverage of lightning strikes are expected. The primary limiting factor for a greater fire-weather threat in this area will be wetting thunderstorm cores and the likelihood of upscale growth of convection into bands/linear segments. The wetting rainfall should keep dry lightning relatively isolated in this area. Likewise, slow-moving convection across Idaho/southwestern Montana should also limit the extent of dry lightning and also result in heavy rainfall in localized areas. The extent of isolated dry lightning strikes will eventually reach Washington State later in the day (late afternoon through early evening). ...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 1059 AM CDT Thu Aug 08 2019 Valid 081700Z - 091200Z The forecast remains on track. Minor modifications have been made to the ISODRYT area based on latest observations and model guidance. Two shortwave troughs are evident in satellite water vapor imagery in northern Nevada and near the southern California coast. These features are already promoting thunderstorm activity and are expected to continue doing so into the afternoon/evening. Thunderstorm coverage may approach 40% within portions of Oregon, but GPS satellite and forecast soundings show increasing PWAT values which will help to mitigate some of the threat for ignitions. ..Wendt.. 08/08/2019 .PREV DISCUSSION... /ISSUED 0110 AM CDT Thu Aug 08 2019/ ...Synopsis... Deep southerly flow between a longwave trough over the northeastern Pacific and a longwave ridge centered over the Great Basin will maintain mid-level moisture in a corridor from Nevada northward to northern Washington State today. Heating beneath this moist plume will promote areas of isolated to scattered thunderstorms, which will serve as the main focus for fire weather threats across the West. ...Nevada, Idaho, southwestern Montana, central and eastern Oregon, and central and eastern Washington State... The aforementioned synoptic pattern and surface heating will foster development and gradual expansion of convective coverage - likely beginning around mid-morning across Nevada and expanding northward through the afternoon and evening. These storms will occur atop widespread areas of dry fuels, favoring lightning-related fire ignition and spread. Additionally, gusty/erratic downburst winds will complicate fire suppression efforts near ongoing fires in the region. The greatest coverage of storms is expected to occur across portions of Nevada during the afternoon, where 40%+ coverage of lightning strikes are expected. The primary limiting factor for a greater fire-weather threat in this area will be wetting thunderstorm cores and the likelihood of upscale growth of convection into bands/linear segments. The wetting rainfall should keep dry lightning relatively isolated in this area. Likewise, slow-moving convection across Idaho/southwestern Montana should also limit the extent of dry lightning and also result in heavy rainfall in localized areas. The extent of isolated dry lightning strikes will eventually reach Washington State later in the day (late afternoon through early evening). ...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 1059 AM CDT Thu Aug 08 2019 Valid 081700Z - 091200Z The forecast remains on track. Minor modifications have been made to the ISODRYT area based on latest observations and model guidance. Two shortwave troughs are evident in satellite water vapor imagery in northern Nevada and near the southern California coast. These features are already promoting thunderstorm activity and are expected to continue doing so into the afternoon/evening. Thunderstorm coverage may approach 40% within portions of Oregon, but GPS satellite and forecast soundings show increasing PWAT values which will help to mitigate some of the threat for ignitions. ..Wendt.. 08/08/2019 .PREV DISCUSSION... /ISSUED 0110 AM CDT Thu Aug 08 2019/ ...Synopsis... Deep southerly flow between a longwave trough over the northeastern Pacific and a longwave ridge centered over the Great Basin will maintain mid-level moisture in a corridor from Nevada northward to northern Washington State today. Heating beneath this moist plume will promote areas of isolated to scattered thunderstorms, which will serve as the main focus for fire weather threats across the West. ...Nevada, Idaho, southwestern Montana, central and eastern Oregon, and central and eastern Washington State... The aforementioned synoptic pattern and surface heating will foster development and gradual expansion of convective coverage - likely beginning around mid-morning across Nevada and expanding northward through the afternoon and evening. These storms will occur atop widespread areas of dry fuels, favoring lightning-related fire ignition and spread. Additionally, gusty/erratic downburst winds will complicate fire suppression efforts near ongoing fires in the region. The greatest coverage of storms is expected to occur across portions of Nevada during the afternoon, where 40%+ coverage of lightning strikes are expected. The primary limiting factor for a greater fire-weather threat in this area will be wetting thunderstorm cores and the likelihood of upscale growth of convection into bands/linear segments. The wetting rainfall should keep dry lightning relatively isolated in this area. Likewise, slow-moving convection across Idaho/southwestern Montana should also limit the extent of dry lightning and also result in heavy rainfall in localized areas. The extent of isolated dry lightning strikes will eventually reach Washington State later in the day (late afternoon through early evening). ...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 1059 AM CDT Thu Aug 08 2019 Valid 081700Z - 091200Z The forecast remains on track. Minor modifications have been made to the ISODRYT area based on latest observations and model guidance. Two shortwave troughs are evident in satellite water vapor imagery in northern Nevada and near the southern California coast. These features are already promoting thunderstorm activity and are expected to continue doing so into the afternoon/evening. Thunderstorm coverage may approach 40% within portions of Oregon, but GPS satellite and forecast soundings show increasing PWAT values which will help to mitigate some of the threat for ignitions. ..Wendt.. 08/08/2019 .PREV DISCUSSION... /ISSUED 0110 AM CDT Thu Aug 08 2019/ ...Synopsis... Deep southerly flow between a longwave trough over the northeastern Pacific and a longwave ridge centered over the Great Basin will maintain mid-level moisture in a corridor from Nevada northward to northern Washington State today. Heating beneath this moist plume will promote areas of isolated to scattered thunderstorms, which will serve as the main focus for fire weather threats across the West. ...Nevada, Idaho, southwestern Montana, central and eastern Oregon, and central and eastern Washington State... The aforementioned synoptic pattern and surface heating will foster development and gradual expansion of convective coverage - likely beginning around mid-morning across Nevada and expanding northward through the afternoon and evening. These storms will occur atop widespread areas of dry fuels, favoring lightning-related fire ignition and spread. Additionally, gusty/erratic downburst winds will complicate fire suppression efforts near ongoing fires in the region. The greatest coverage of storms is expected to occur across portions of Nevada during the afternoon, where 40%+ coverage of lightning strikes are expected. The primary limiting factor for a greater fire-weather threat in this area will be wetting thunderstorm cores and the likelihood of upscale growth of convection into bands/linear segments. The wetting rainfall should keep dry lightning relatively isolated in this area. Likewise, slow-moving convection across Idaho/southwestern Montana should also limit the extent of dry lightning and also result in heavy rainfall in localized areas. The extent of isolated dry lightning strikes will eventually reach Washington State later in the day (late afternoon through early evening). ...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 1059 AM CDT Thu Aug 08 2019 Valid 081700Z - 091200Z The forecast remains on track. Minor modifications have been made to the ISODRYT area based on latest observations and model guidance. Two shortwave troughs are evident in satellite water vapor imagery in northern Nevada and near the southern California coast. These features are already promoting thunderstorm activity and are expected to continue doing so into the afternoon/evening. Thunderstorm coverage may approach 40% within portions of Oregon, but GPS satellite and forecast soundings show increasing PWAT values which will help to mitigate some of the threat for ignitions. ..Wendt.. 08/08/2019 .PREV DISCUSSION... /ISSUED 0110 AM CDT Thu Aug 08 2019/ ...Synopsis... Deep southerly flow between a longwave trough over the northeastern Pacific and a longwave ridge centered over the Great Basin will maintain mid-level moisture in a corridor from Nevada northward to northern Washington State today. Heating beneath this moist plume will promote areas of isolated to scattered thunderstorms, which will serve as the main focus for fire weather threats across the West. ...Nevada, Idaho, southwestern Montana, central and eastern Oregon, and central and eastern Washington State... The aforementioned synoptic pattern and surface heating will foster development and gradual expansion of convective coverage - likely beginning around mid-morning across Nevada and expanding northward through the afternoon and evening. These storms will occur atop widespread areas of dry fuels, favoring lightning-related fire ignition and spread. Additionally, gusty/erratic downburst winds will complicate fire suppression efforts near ongoing fires in the region. The greatest coverage of storms is expected to occur across portions of Nevada during the afternoon, where 40%+ coverage of lightning strikes are expected. The primary limiting factor for a greater fire-weather threat in this area will be wetting thunderstorm cores and the likelihood of upscale growth of convection into bands/linear segments. The wetting rainfall should keep dry lightning relatively isolated in this area. Likewise, slow-moving convection across Idaho/southwestern Montana should also limit the extent of dry lightning and also result in heavy rainfall in localized areas. The extent of isolated dry lightning strikes will eventually reach Washington State later in the day (late afternoon through early evening). ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Thu Aug 8 16:02:02 UTC 2019.

MD 1674 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR CENTRAL AND NORTHERN NY...NORTH-CENTRAL PA
Mesoscale Discussion 1674 NWS Storm Prediction Center Norman OK 1058 AM CDT Thu Aug 08 2019 Areas affected...central and northern NY...north-central PA Concerning...Severe potential...Watch possible Valid 081558Z - 081730Z Probability of Watch Issuance...60 percent SUMMARY...The potential for strong to locally severe gusts (45-60mph) will probably increase through midday and into the early afternoon as a squall line moves from western into central and northern NY. DISCUSSION...Radar mosaic shows a squall line over western NY as of 1150am EDT. The 7am Buffalo raob showed meager buoyancy and relatively weak westerly flow from just above the surface through 300mb. Surface heating has occurred this morning with temperatures on the NY Mesonet rising into the upper 70 to lower 80s degrees F immediately east of the squall line. KIAG measured a 40kt gust at 1039am. The NY Mesonet has up until recently only observed 33mph at 3 sites thus far. However, the NY Mesonet Batavia site very recently observed a measured gust of 47mph. RAP forecast soundings show several hundred J/kg MLCAPE developing by early afternoon across central NY. As the mid-level shortwave trough over Ontario and the lower Great Lakes progresses eastward, storm intensity is forecast to increase aided in part by the associated forcing for ascent and diurnal destabilization. Isolated wind damage owing to gusts ranging from 45-55mph (locally up to 60mph) is possible. ..Smith/Goss.. 08/08/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BTV...ALY...BGM...BUF...CTP...PBZ... LAT...LON 41337933 42517802 43417715 44647615 45047477 44377401 43217406 42047485 41397611 41337933 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0756 AM CDT Thu Aug 08 2019 Valid 081300Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE LOWER GREAT LAKES AND NORTH-CENTRAL APPALACHIANS TO THE MID/UPPER OHIO VALLEY... ...SUMMARY... The greatest concentration of potentially severe storms today should be from the lower Great Lakes and north-central Appalachians to the mid/upper Ohio Valley. ...Synopsis... In mid/upper levels, the CONUS subset of the large-scale pattern will continue to feature a mean ridge in the West, from a TX anticyclone to the northern Rockies, and troughing from eastern Canada down the Appalachians. However, some breakdown of the ridging will occur as a series of variably amplified shortwave impinges on its northwestern parts. Two of those perturbations follow each other in quick succession and are evident in moisture channel imagery: the first from over northwestern NV to southwestern UT, the second over the Pacific, approaching the CA Channel Islands. Both of these features will move northeastward across the Great Basin through the period, with the leading one reaching the northern Rockies by 12Z. A series of shortwaves also will traverse the extensive cyclonic- flow field over the Great Lakes and Northeast regions, anchored by a large cyclone over far northern ON and Hudson Bay. Among those is a convectively enhanced vorticity lobe, now apparent in satellite and composited radar imagery from Lake Huron to northern/eastern IN. This perturbation will pivot across the Lower Great Lakes and adjoining states through tonight, following a leading shortwave now ejecting across New England. Meanwhile, in a zone of weaker, difluent flow aloft, convectively induced vorticity lobes will move slowly southeastward over a corridor from KS to the Mid-South. At the surface, 11Z analysis showed a cold front from northwestern Lake Huron across central Lake Michigan, central IA and northern NE, becoming a warm front over southeastern MT to a low near GTF. The eastern portion of this front should proceed eastward across the lower Great Lakes, much of New England, and parts of the Mid- Atlantic through the period. An outflow-reinforced baroclinic zone was evident over northern MS, northern AR, and northern OK, quasistationary except for a southward shunting by convective processes over OK and parts of northern AR. ...Lower Great Lakes to Ohio Valley... Widely scattered to scattered thunderstorms will develop from late morning through the afternoon over western parts of the outlook area, moving somewhat southeastward across the central Appalachians region and eastward to east-northeastward over NY, in close accordance with the cyclonic ambient-flow pattern. Convection should increase in coverage/intensity as it moves into a favorably moist and destabilizing boundary layer. Occasional large hail and damaging to severe gusts will be the main concerns. Activity may form along but mainly ahead of the surface cold front, in areas of weak pre-frontal surface troughing and low-level convergence/heating where MLCINH is locally minimized. Sever hours of strong, direct heating of the near-surface layer with 60s F dew points should occur over most of the area, given the lack of clouds evident in satellite imagery. Meanwhile, the large-scale lift/DCVA field of the shortwave trough should provide supportive destabilization aloft. This should permit a patchy prefrontal corridor of 1000-1500 J/kg MLCAPE to develop, atop steep boundary- layer lapse rates and a well-mixed subcloud layer. Lack of stronger shear area-wide will be a limiting factor for an even better- organized event, though pockets of 30-40 kt effective-shear magnitudes appear possible. Severe potential should weaken with eastward extent and time this evening, into a stabilizing thermodynamic regime. ...Eastern Rockies to central/southern Plains... Two physically distinct regimes will contribute to strong/severe thunderstorm potential today into this evening, with activity moving generally eastward to southeastward around the upper high/ridge. These areas have been split up spatially due to convective/precip trends since the prior outlook: 1. A large area of precip and embedded, non-severe thunderstorms in evident initially from central KS across northeastern OK to the Ozarks of northern AR, supported by warm advection and related lift to LFC northeast of the surface front. A brief/isolated severe-hail event cannot be ruled out in this regime for a few more hours. Additional, widely scattered to scattered thunderstorms are expected to form this afternoon along associated outflow/differential-heating boundaries, offering the threat for isolated large hail and damaging to severe gusts. MCVs now apparent over the northeastern TX Panhandle and west-central KS may provide mesoscale mass-response enhancement in support of storm organization as they shift east-southeastward to southeastward. More-sustained diurnal heating of the favorably moist boundary layer over eastern OK and AR will yield 2000-3000 J/kg MLCAPE, transitioning to 1000-2000 J/kg under more cloud cover to the west. Weak low/middle-level winds and lack of stronger shear should limit overall organization, though localized clustering of damaging gusts may occur where driven by aggregation of multicellular cold pools. 2. Farther west, scattered thunderstorms should develop this afternoon over the eastern WY mountains southward over the CO Front Range and Sangre de Cristos, as well as adjoining foothills and eastward-extending topographic ridges. Sporadic/isolated damaging gusts and severe hail will be possible from the most intense cores. Formation of one or two small MCSs with locally maximized wind-corridor potential also cannot be ruled out as convection moves onto the adjoining High Plains, and into a well-heated/mixed boundary layer supporting a transition from mixed hail/wind threat to mostly wind. In the absence of substantial upper forcing or LLJ activity, convection generally should weaken this evening in keeping with stabilization of the nocturnal boundary layer. ...Great Basin to extreme southern ID... Isolated thunderstorms already have been noted over the southern Sierra and northwest of LAS during the pre-dawn hours, beneath the leading shortwave perturbation. Episodic, widely scattered to scattered thunderstorms are possible across a large part of the Great Basin today in association with both mid/upper level troughs. At least marginal unconditional risk for strong/locally severe gusts is apparent from midday through afternoon -- mainly over areas of western UT and eastern NV that can diabatically destabilize through pre-existing cloud cover, ahead of the densest cloud/precip areas. Thermodynamic support also will be provided by a plume of low-level monsoonal moisture. Preconvective, lower-elevation surface dew points commonly in the 40s over western parts of the outlook area 50s in UT will support MLCAPE mainly in the 500-1000 J/kg range, locally a bit lower or higher. Slight enhancement to the ambient southwest flow is possible in mid/upper levels near each trough, leading to modest but sufficient deep shear for storm organization. Some clustering and cold-pool aggregation may occur as well in support of a more-concentrated wind swath within this broader area, but this depends on mesoscale to storm-scale processes still unresolved. The overall threat should diminish with time this evening int ID and central UT as nocturnal/diabatic stabilization and outflow stabilize the boundary layer. ..Edwards/Broyles.. 08/08/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0756 AM CDT Thu Aug 08 2019 Valid 081300Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE LOWER GREAT LAKES AND NORTH-CENTRAL APPALACHIANS TO THE MID/UPPER OHIO VALLEY... ...SUMMARY... The greatest concentration of potentially severe storms today should be from the lower Great Lakes and north-central Appalachians to the mid/upper Ohio Valley. ...Synopsis... In mid/upper levels, the CONUS subset of the large-scale pattern will continue to feature a mean ridge in the West, from a TX anticyclone to the northern Rockies, and troughing from eastern Canada down the Appalachians. However, some breakdown of the ridging will occur as a series of variably amplified shortwave impinges on its northwestern parts. Two of those perturbations follow each other in quick succession and are evident in moisture channel imagery: the first from over northwestern NV to southwestern UT, the second over the Pacific, approaching the CA Channel Islands. Both of these features will move northeastward across the Great Basin through the period, with the leading one reaching the northern Rockies by 12Z. A series of shortwaves also will traverse the extensive cyclonic- flow field over the Great Lakes and Northeast regions, anchored by a large cyclone over far northern ON and Hudson Bay. Among those is a convectively enhanced vorticity lobe, now apparent in satellite and composited radar imagery from Lake Huron to northern/eastern IN. This perturbation will pivot across the Lower Great Lakes and adjoining states through tonight, following a leading shortwave now ejecting across New England. Meanwhile, in a zone of weaker, difluent flow aloft, convectively induced vorticity lobes will move slowly southeastward over a corridor from KS to the Mid-South. At the surface, 11Z analysis showed a cold front from northwestern Lake Huron across central Lake Michigan, central IA and northern NE, becoming a warm front over southeastern MT to a low near GTF. The eastern portion of this front should proceed eastward across the lower Great Lakes, much of New England, and parts of the Mid- Atlantic through the period. An outflow-reinforced baroclinic zone was evident over northern MS, northern AR, and northern OK, quasistationary except for a southward shunting by convective processes over OK and parts of northern AR. ...Lower Great Lakes to Ohio Valley... Widely scattered to scattered thunderstorms will develop from late morning through the afternoon over western parts of the outlook area, moving somewhat southeastward across the central Appalachians region and eastward to east-northeastward over NY, in close accordance with the cyclonic ambient-flow pattern. Convection should increase in coverage/intensity as it moves into a favorably moist and destabilizing boundary layer. Occasional large hail and damaging to severe gusts will be the main concerns. Activity may form along but mainly ahead of the surface cold front, in areas of weak pre-frontal surface troughing and low-level convergence/heating where MLCINH is locally minimized. Sever hours of strong, direct heating of the near-surface layer with 60s F dew points should occur over most of the area, given the lack of clouds evident in satellite imagery. Meanwhile, the large-scale lift/DCVA field of the shortwave trough should provide supportive destabilization aloft. This should permit a patchy prefrontal corridor of 1000-1500 J/kg MLCAPE to develop, atop steep boundary- layer lapse rates and a well-mixed subcloud layer. Lack of stronger shear area-wide will be a limiting factor for an even better- organized event, though pockets of 30-40 kt effective-shear magnitudes appear possible. Severe potential should weaken with eastward extent and time this evening, into a stabilizing thermodynamic regime. ...Eastern Rockies to central/southern Plains... Two physically distinct regimes will contribute to strong/severe thunderstorm potential today into this evening, with activity moving generally eastward to southeastward around the upper high/ridge. These areas have been split up spatially due to convective/precip trends since the prior outlook: 1. A large area of precip and embedded, non-severe thunderstorms in evident initially from central KS across northeastern OK to the Ozarks of northern AR, supported by warm advection and related lift to LFC northeast of the surface front. A brief/isolated severe-hail event cannot be ruled out in this regime for a few more hours. Additional, widely scattered to scattered thunderstorms are expected to form this afternoon along associated outflow/differential-heating boundaries, offering the threat for isolated large hail and damaging to severe gusts. MCVs now apparent over the northeastern TX Panhandle and west-central KS may provide mesoscale mass-response enhancement in support of storm organization as they shift east-southeastward to southeastward. More-sustained diurnal heating of the favorably moist boundary layer over eastern OK and AR will yield 2000-3000 J/kg MLCAPE, transitioning to 1000-2000 J/kg under more cloud cover to the west. Weak low/middle-level winds and lack of stronger shear should limit overall organization, though localized clustering of damaging gusts may occur where driven by aggregation of multicellular cold pools. 2. Farther west, scattered thunderstorms should develop this afternoon over the eastern WY mountains southward over the CO Front Range and Sangre de Cristos, as well as adjoining foothills and eastward-extending topographic ridges. Sporadic/isolated damaging gusts and severe hail will be possible from the most intense cores. Formation of one or two small MCSs with locally maximized wind-corridor potential also cannot be ruled out as convection moves onto the adjoining High Plains, and into a well-heated/mixed boundary layer supporting a transition from mixed hail/wind threat to mostly wind. In the absence of substantial upper forcing or LLJ activity, convection generally should weaken this evening in keeping with stabilization of the nocturnal boundary layer. ...Great Basin to extreme southern ID... Isolated thunderstorms already have been noted over the southern Sierra and northwest of LAS during the pre-dawn hours, beneath the leading shortwave perturbation. Episodic, widely scattered to scattered thunderstorms are possible across a large part of the Great Basin today in association with both mid/upper level troughs. At least marginal unconditional risk for strong/locally severe gusts is apparent from midday through afternoon -- mainly over areas of western UT and eastern NV that can diabatically destabilize through pre-existing cloud cover, ahead of the densest cloud/precip areas. Thermodynamic support also will be provided by a plume of low-level monsoonal moisture. Preconvective, lower-elevation surface dew points commonly in the 40s over western parts of the outlook area 50s in UT will support MLCAPE mainly in the 500-1000 J/kg range, locally a bit lower or higher. Slight enhancement to the ambient southwest flow is possible in mid/upper levels near each trough, leading to modest but sufficient deep shear for storm organization. Some clustering and cold-pool aggregation may occur as well in support of a more-concentrated wind swath within this broader area, but this depends on mesoscale to storm-scale processes still unresolved. The overall threat should diminish with time this evening int ID and central UT as nocturnal/diabatic stabilization and outflow stabilize the boundary layer. ..Edwards/Broyles.. 08/08/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0756 AM CDT Thu Aug 08 2019 Valid 081300Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE LOWER GREAT LAKES AND NORTH-CENTRAL APPALACHIANS TO THE MID/UPPER OHIO VALLEY... ...SUMMARY... The greatest concentration of potentially severe storms today should be from the lower Great Lakes and north-central Appalachians to the mid/upper Ohio Valley. ...Synopsis... In mid/upper levels, the CONUS subset of the large-scale pattern will continue to feature a mean ridge in the West, from a TX anticyclone to the northern Rockies, and troughing from eastern Canada down the Appalachians. However, some breakdown of the ridging will occur as a series of variably amplified shortwave impinges on its northwestern parts. Two of those perturbations follow each other in quick succession and are evident in moisture channel imagery: the first from over northwestern NV to southwestern UT, the second over the Pacific, approaching the CA Channel Islands. Both of these features will move northeastward across the Great Basin through the period, with the leading one reaching the northern Rockies by 12Z. A series of shortwaves also will traverse the extensive cyclonic- flow field over the Great Lakes and Northeast regions, anchored by a large cyclone over far northern ON and Hudson Bay. Among those is a convectively enhanced vorticity lobe, now apparent in satellite and composited radar imagery from Lake Huron to northern/eastern IN. This perturbation will pivot across the Lower Great Lakes and adjoining states through tonight, following a leading shortwave now ejecting across New England. Meanwhile, in a zone of weaker, difluent flow aloft, convectively induced vorticity lobes will move slowly southeastward over a corridor from KS to the Mid-South. At the surface, 11Z analysis showed a cold front from northwestern Lake Huron across central Lake Michigan, central IA and northern NE, becoming a warm front over southeastern MT to a low near GTF. The eastern portion of this front should proceed eastward across the lower Great Lakes, much of New England, and parts of the Mid- Atlantic through the period. An outflow-reinforced baroclinic zone was evident over northern MS, northern AR, and northern OK, quasistationary except for a southward shunting by convective processes over OK and parts of northern AR. ...Lower Great Lakes to Ohio Valley... Widely scattered to scattered thunderstorms will develop from late morning through the afternoon over western parts of the outlook area, moving somewhat southeastward across the central Appalachians region and eastward to east-northeastward over NY, in close accordance with the cyclonic ambient-flow pattern. Convection should increase in coverage/intensity as it moves into a favorably moist and destabilizing boundary layer. Occasional large hail and damaging to severe gusts will be the main concerns. Activity may form along but mainly ahead of the surface cold front, in areas of weak pre-frontal surface troughing and low-level convergence/heating where MLCINH is locally minimized. Sever hours of strong, direct heating of the near-surface layer with 60s F dew points should occur over most of the area, given the lack of clouds evident in satellite imagery. Meanwhile, the large-scale lift/DCVA field of the shortwave trough should provide supportive destabilization aloft. This should permit a patchy prefrontal corridor of 1000-1500 J/kg MLCAPE to develop, atop steep boundary- layer lapse rates and a well-mixed subcloud layer. Lack of stronger shear area-wide will be a limiting factor for an even better- organized event, though pockets of 30-40 kt effective-shear magnitudes appear possible. Severe potential should weaken with eastward extent and time this evening, into a stabilizing thermodynamic regime. ...Eastern Rockies to central/southern Plains... Two physically distinct regimes will contribute to strong/severe thunderstorm potential today into this evening, with activity moving generally eastward to southeastward around the upper high/ridge. These areas have been split up spatially due to convective/precip trends since the prior outlook: 1. A large area of precip and embedded, non-severe thunderstorms in evident initially from central KS across northeastern OK to the Ozarks of northern AR, supported by warm advection and related lift to LFC northeast of the surface front. A brief/isolated severe-hail event cannot be ruled out in this regime for a few more hours. Additional, widely scattered to scattered thunderstorms are expected to form this afternoon along associated outflow/differential-heating boundaries, offering the threat for isolated large hail and damaging to severe gusts. MCVs now apparent over the northeastern TX Panhandle and west-central KS may provide mesoscale mass-response enhancement in support of storm organization as they shift east-southeastward to southeastward. More-sustained diurnal heating of the favorably moist boundary layer over eastern OK and AR will yield 2000-3000 J/kg MLCAPE, transitioning to 1000-2000 J/kg under more cloud cover to the west. Weak low/middle-level winds and lack of stronger shear should limit overall organization, though localized clustering of damaging gusts may occur where driven by aggregation of multicellular cold pools. 2. Farther west, scattered thunderstorms should develop this afternoon over the eastern WY mountains southward over the CO Front Range and Sangre de Cristos, as well as adjoining foothills and eastward-extending topographic ridges. Sporadic/isolated damaging gusts and severe hail will be possible from the most intense cores. Formation of one or two small MCSs with locally maximized wind-corridor potential also cannot be ruled out as convection moves onto the adjoining High Plains, and into a well-heated/mixed boundary layer supporting a transition from mixed hail/wind threat to mostly wind. In the absence of substantial upper forcing or LLJ activity, convection generally should weaken this evening in keeping with stabilization of the nocturnal boundary layer. ...Great Basin to extreme southern ID... Isolated thunderstorms already have been noted over the southern Sierra and northwest of LAS during the pre-dawn hours, beneath the leading shortwave perturbation. Episodic, widely scattered to scattered thunderstorms are possible across a large part of the Great Basin today in association with both mid/upper level troughs. At least marginal unconditional risk for strong/locally severe gusts is apparent from midday through afternoon -- mainly over areas of western UT and eastern NV that can diabatically destabilize through pre-existing cloud cover, ahead of the densest cloud/precip areas. Thermodynamic support also will be provided by a plume of low-level monsoonal moisture. Preconvective, lower-elevation surface dew points commonly in the 40s over western parts of the outlook area 50s in UT will support MLCAPE mainly in the 500-1000 J/kg range, locally a bit lower or higher. Slight enhancement to the ambient southwest flow is possible in mid/upper levels near each trough, leading to modest but sufficient deep shear for storm organization. Some clustering and cold-pool aggregation may occur as well in support of a more-concentrated wind swath within this broader area, but this depends on mesoscale to storm-scale processes still unresolved. The overall threat should diminish with time this evening int ID and central UT as nocturnal/diabatic stabilization and outflow stabilize the boundary layer. ..Edwards/Broyles.. 08/08/2019 Read more

000
ABPZ20 KNHC 081140
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Thu Aug 8 2019

For the eastern North Pacific...east of 140 degrees west longitude:

A low pressure area is forecast to form a few hundred miles south
or southwest of the southern coast of Mexico by the end of the week
or early next week. Thereafter, environmental conditions are
expected to be somewhat conducive for development, and a tropical
depression could form next week while it moves west-northwestward at
10 to 15 mph, offshore of the southwestern coast of Mexico.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...medium...50 percent.

$$
Forecaster Pasch

000
ABNT20 KNHC 081102
TWOAT

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Thu Aug 8 2019

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

Tropical cyclone formation is not expected during the next 5 days.

$$
Forecaster Stewart

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0335 AM CDT Thu Aug 08 2019 Valid 111200Z - 161200Z ...DISCUSSION... Forecast guidance generally maintains a strong upper anticyclone over the south-central U.S. Meanwhile, less-amplified, but still progressive northern-stream flow will bring several shortwave impulses across the northern Plains, Great Lakes and Northeast during the forecast period, though timing of these features and any mesoscale influences from multiple days of convection over the next week is uncertain. This is in part due to inconsistency between forecast models and also poor resolution of finer-scale features at these timescales. As a result, predictability is too low to include severe probabilities at this time. Read more