Severe Storms

MD 1686 CONCERNING SEVERE POTENTIAL...SEVERE THUNDERSTORM WATCH LIKELY FOR PORTIONS OF EASTERN OR...FAR SOUTHEAST WA...SOUTHWEST AND CENTRAL ID AND WESTERN MT
Mesoscale Discussion 1686 NWS Storm Prediction Center Norman OK 1241 PM CDT Sat Aug 10 2019 Areas affected...portions of eastern OR...far southeast WA...southwest and central ID and western MT Concerning...Severe potential...Severe Thunderstorm Watch likely Valid 101741Z - 101945Z Probability of Watch Issuance...80 percent SUMMARY...Thunderstorms will increase in coverage and intensity from far eastern OR into central ID and western MT over the next couple of hours. Large hail and damaging winds will be the main threats with these storms and a watch will likely be needed. DISCUSSION...Forcing for ascent is increasing across the northern Rockies late this morning, per increasing thunderstorm activity near the OR/ID border and more recently across central ID. Strong heating to the north and east of this activity is resulting in a quickly destabilizing airmass characterized by unusually high dewpoints, ranging from the low to mid 50s F mostly, but several areas are approaching 60F. As a result, MLCAPE increasing to around 1500 J/kg is expected in a swath from central ID into western MT by early afternoon. This should result in vigorous thunderstorm development over the next couple of hours over higher terrain. Effective shear greater than 35 kt will allow cells to quickly become organized with rotating updrafts and possibly some supercell structures. Midlevel lapse rates are very steep, as evident in 12z regional RAOBs. Combined with favorable vertical shear profiles, large hail will be possible. Furthermore, storms will likely be high-based as boundary layer moisture mixes out with increased heating. Steepening low level lapse rates will result and fast storm motion will aid in strong wind gust potential as well. Where higher dewpoints are maintained, forecast guidance suggests there could be a brief, conditional tornado threat, mainly over parts of western MT where east/southeasterly low level flow will enhanced effective SRH. However, this threat is more uncertain than the expected large hail and strong, locally damaging gusts. The severe threat will continue to increase over the next couple of hours as additional heating reduces inhibition and forcing for ascent continues to increase. A severe thunderstorms watch will likely be needed by 19 or 20z. ..Leitman/Grams.. 08/10/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...TFX...PIH...MSO...BOI...OTX...PDT... LAT...LON 45411096 44971189 44531336 44011425 43211496 42591549 42261634 42171700 42421794 43091864 44141957 44701987 45251985 45931919 46631814 47021743 47471571 47751386 47711302 47411188 46831112 45861101 45411096 Read more

MD 1685 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR SOUTHEAST NC...NORTHEAST SC
Mesoscale Discussion 1685 NWS Storm Prediction Center Norman OK 1237 PM CDT Sat Aug 10 2019 Areas affected...Southeast NC...Northeast SC Concerning...Severe potential...Watch unlikely Valid 101737Z - 101930Z Probability of Watch Issuance...20 percent SUMMARY...A few thunderstorms capable of locally damaging winds and perhaps some hail are possible this afternoon. Watch issuance is currently considered unlikely due to the limited areal extent of the threat. DISCUSSION...As of 1730Z, cumulus is increasing along a weak surface boundary across southeast NC, and also along the sea breeze from coastal portions of northeast SC into southeast NC. Temperatures rising into the low 90s F combined with rich low-level moisture are resulting in the development of moderate buoyancy, with MLCAPE already in the 1000-1500 J/kg range (per recent mesoanalyses) and some further increase possible this afternoon. Meanwhile, moderate mid/upper-level flow on the periphery of a deep upper trough over the Northeast is resulting in effective shear of 25-35 kt across the region. This shear will be sufficient to support some updraft organization with any deep convection that develops this afternoon. Locally damaging wind will be a threat given the potential for water-loading within a very moist environment, while any well-organized multicell or supercell structures that develop will have some hail potential, despite relatively warm temperatures aloft. The areal extent of the primary threat is expected to remain confined to near the coast, and the number of storms within the threat area remains uncertain given generally limited large-scale ascent across the region. Given these factors, watch issuance is considered unlikely, though a conditional severe threat will be present with any storms this afternoon. ..Dean/Grams.. 08/10/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MHX...RAH...ILM...CHS... LAT...LON 33777808 33407864 32887915 32827977 33147970 33917917 35067849 35167796 35237724 35227676 35097640 34887622 34777647 34667654 34457699 34177744 33777808 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1234 PM CDT Sat Aug 10 2019 Valid 111200Z - 121200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR SOUTHWEST NEBRASKA... ...SUMMARY... Areas of strong to severe storms are expected over portions of the northern through central High Plains Sunday afternoon into Sunday night. Large hail and severe gusts are the primary threats. ...Synopsis... Upper trough now approaching northern CA will transition to an open wave and continue through the northern Rockies and northern High Plains Sunday and Sunday night, flattening the northern periphery of an upper ridge centered over the southern Plains. A mid-level disturbance of convective origin was analyzed over far southeast AZ midday Saturday. The disturbance is forecast to move north and northeastward across western NM/CO before reaching northeast CO by early evening Sunday. Sunday morning a cold front will extend from northern MN southwest into northeast WY. The western extension of this boundary will stall before moving north as a warm front through eastern MT. A secondary front will extend from a weak surface low in IA westward through southern NE. The western extension of this boundary will stall near the KS/NE border. ...Central High Plains region... Early-day storms are forecast over KS/NE into the lower MO Valley within zone of isentropic ascent. This activity is expected to diminish as it moves east-southeastward during the day. In wake of morning storms, rich low-level moisture with mid-upper 60s F dewpoints and diabatic warming will support a corridor of moderate to strong instability (2000-2500 J/kg MLCAPE) in vicinity of the stalled front over northern KS/southern NE. Easterly upslope flow will exist north of this boundary, and storms are expected to develop over the higher terrain in association with the central Rockies impulse, as well as near the front/lee trough intersection during the late afternoon and spread east during the evening. A belt of moderate (30-35 kt) southwesterly mid-level winds will overspread the central High Plains from northeast CO into southwest NE. Some supercells are possible early over CO before outflow becomes more pervasive and storms grow upscale into clusters/lines as they develop east towards the KS/NE/CO border before spreading east overnight. Severe gusts will be the primary hazard once storms grow upscale. ...Northern Rockies through northern High Plains... Moist axis will be shunted southwestward by the south-advancing cold front, before retreating back north as a warm front through eastern MT. The corridor of modest low-level moisture with upper 50s F dewpoints beneath steep mid-level lapse rates will support moderate instability (1500-2000 J/kg from central MT through northeast WY and possibly southwest SD) as the surface layer warms during the afternoon. Storms are expected to develop over the higher terrain and spread northeast through the relatively narrow instability corridor during the afternoon and early evening. A belt of stronger winds aloft accompanying the upper trough will support 40-45 kt effective bulk shear supportive of organized storms. Large hail and severe gusts associated with high-based supercells will likely transition into outflow-efficient clusters capable of severe gusts. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 30% - Enhanced Hail: 15% - Slight ..Smith.. 08/10/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1234 PM CDT Sat Aug 10 2019 Valid 111200Z - 121200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR SOUTHWEST NEBRASKA... ...SUMMARY... Areas of strong to severe storms are expected over portions of the northern through central High Plains Sunday afternoon into Sunday night. Large hail and severe gusts are the primary threats. ...Synopsis... Upper trough now approaching northern CA will transition to an open wave and continue through the northern Rockies and northern High Plains Sunday and Sunday night, flattening the northern periphery of an upper ridge centered over the southern Plains. A mid-level disturbance of convective origin was analyzed over far southeast AZ midday Saturday. The disturbance is forecast to move north and northeastward across western NM/CO before reaching northeast CO by early evening Sunday. Sunday morning a cold front will extend from northern MN southwest into northeast WY. The western extension of this boundary will stall before moving north as a warm front through eastern MT. A secondary front will extend from a weak surface low in IA westward through southern NE. The western extension of this boundary will stall near the KS/NE border. ...Central High Plains region... Early-day storms are forecast over KS/NE into the lower MO Valley within zone of isentropic ascent. This activity is expected to diminish as it moves east-southeastward during the day. In wake of morning storms, rich low-level moisture with mid-upper 60s F dewpoints and diabatic warming will support a corridor of moderate to strong instability (2000-2500 J/kg MLCAPE) in vicinity of the stalled front over northern KS/southern NE. Easterly upslope flow will exist north of this boundary, and storms are expected to develop over the higher terrain in association with the central Rockies impulse, as well as near the front/lee trough intersection during the late afternoon and spread east during the evening. A belt of moderate (30-35 kt) southwesterly mid-level winds will overspread the central High Plains from northeast CO into southwest NE. Some supercells are possible early over CO before outflow becomes more pervasive and storms grow upscale into clusters/lines as they develop east towards the KS/NE/CO border before spreading east overnight. Severe gusts will be the primary hazard once storms grow upscale. ...Northern Rockies through northern High Plains... Moist axis will be shunted southwestward by the south-advancing cold front, before retreating back north as a warm front through eastern MT. The corridor of modest low-level moisture with upper 50s F dewpoints beneath steep mid-level lapse rates will support moderate instability (1500-2000 J/kg from central MT through northeast WY and possibly southwest SD) as the surface layer warms during the afternoon. Storms are expected to develop over the higher terrain and spread northeast through the relatively narrow instability corridor during the afternoon and early evening. A belt of stronger winds aloft accompanying the upper trough will support 40-45 kt effective bulk shear supportive of organized storms. Large hail and severe gusts associated with high-based supercells will likely transition into outflow-efficient clusters capable of severe gusts. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 30% - Enhanced Hail: 15% - Slight ..Smith.. 08/10/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1234 PM CDT Sat Aug 10 2019 Valid 111200Z - 121200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR SOUTHWEST NEBRASKA... ...SUMMARY... Areas of strong to severe storms are expected over portions of the northern through central High Plains Sunday afternoon into Sunday night. Large hail and severe gusts are the primary threats. ...Synopsis... Upper trough now approaching northern CA will transition to an open wave and continue through the northern Rockies and northern High Plains Sunday and Sunday night, flattening the northern periphery of an upper ridge centered over the southern Plains. A mid-level disturbance of convective origin was analyzed over far southeast AZ midday Saturday. The disturbance is forecast to move north and northeastward across western NM/CO before reaching northeast CO by early evening Sunday. Sunday morning a cold front will extend from northern MN southwest into northeast WY. The western extension of this boundary will stall before moving north as a warm front through eastern MT. A secondary front will extend from a weak surface low in IA westward through southern NE. The western extension of this boundary will stall near the KS/NE border. ...Central High Plains region... Early-day storms are forecast over KS/NE into the lower MO Valley within zone of isentropic ascent. This activity is expected to diminish as it moves east-southeastward during the day. In wake of morning storms, rich low-level moisture with mid-upper 60s F dewpoints and diabatic warming will support a corridor of moderate to strong instability (2000-2500 J/kg MLCAPE) in vicinity of the stalled front over northern KS/southern NE. Easterly upslope flow will exist north of this boundary, and storms are expected to develop over the higher terrain in association with the central Rockies impulse, as well as near the front/lee trough intersection during the late afternoon and spread east during the evening. A belt of moderate (30-35 kt) southwesterly mid-level winds will overspread the central High Plains from northeast CO into southwest NE. Some supercells are possible early over CO before outflow becomes more pervasive and storms grow upscale into clusters/lines as they develop east towards the KS/NE/CO border before spreading east overnight. Severe gusts will be the primary hazard once storms grow upscale. ...Northern Rockies through northern High Plains... Moist axis will be shunted southwestward by the south-advancing cold front, before retreating back north as a warm front through eastern MT. The corridor of modest low-level moisture with upper 50s F dewpoints beneath steep mid-level lapse rates will support moderate instability (1500-2000 J/kg from central MT through northeast WY and possibly southwest SD) as the surface layer warms during the afternoon. Storms are expected to develop over the higher terrain and spread northeast through the relatively narrow instability corridor during the afternoon and early evening. A belt of stronger winds aloft accompanying the upper trough will support 40-45 kt effective bulk shear supportive of organized storms. Large hail and severe gusts associated with high-based supercells will likely transition into outflow-efficient clusters capable of severe gusts. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 30% - Enhanced Hail: 15% - Slight ..Smith.. 08/10/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1234 PM CDT Sat Aug 10 2019 Valid 111200Z - 121200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR SOUTHWEST NEBRASKA... ...SUMMARY... Areas of strong to severe storms are expected over portions of the northern through central High Plains Sunday afternoon into Sunday night. Large hail and severe gusts are the primary threats. ...Synopsis... Upper trough now approaching northern CA will transition to an open wave and continue through the northern Rockies and northern High Plains Sunday and Sunday night, flattening the northern periphery of an upper ridge centered over the southern Plains. A mid-level disturbance of convective origin was analyzed over far southeast AZ midday Saturday. The disturbance is forecast to move north and northeastward across western NM/CO before reaching northeast CO by early evening Sunday. Sunday morning a cold front will extend from northern MN southwest into northeast WY. The western extension of this boundary will stall before moving north as a warm front through eastern MT. A secondary front will extend from a weak surface low in IA westward through southern NE. The western extension of this boundary will stall near the KS/NE border. ...Central High Plains region... Early-day storms are forecast over KS/NE into the lower MO Valley within zone of isentropic ascent. This activity is expected to diminish as it moves east-southeastward during the day. In wake of morning storms, rich low-level moisture with mid-upper 60s F dewpoints and diabatic warming will support a corridor of moderate to strong instability (2000-2500 J/kg MLCAPE) in vicinity of the stalled front over northern KS/southern NE. Easterly upslope flow will exist north of this boundary, and storms are expected to develop over the higher terrain in association with the central Rockies impulse, as well as near the front/lee trough intersection during the late afternoon and spread east during the evening. A belt of moderate (30-35 kt) southwesterly mid-level winds will overspread the central High Plains from northeast CO into southwest NE. Some supercells are possible early over CO before outflow becomes more pervasive and storms grow upscale into clusters/lines as they develop east towards the KS/NE/CO border before spreading east overnight. Severe gusts will be the primary hazard once storms grow upscale. ...Northern Rockies through northern High Plains... Moist axis will be shunted southwestward by the south-advancing cold front, before retreating back north as a warm front through eastern MT. The corridor of modest low-level moisture with upper 50s F dewpoints beneath steep mid-level lapse rates will support moderate instability (1500-2000 J/kg from central MT through northeast WY and possibly southwest SD) as the surface layer warms during the afternoon. Storms are expected to develop over the higher terrain and spread northeast through the relatively narrow instability corridor during the afternoon and early evening. A belt of stronger winds aloft accompanying the upper trough will support 40-45 kt effective bulk shear supportive of organized storms. Large hail and severe gusts associated with high-based supercells will likely transition into outflow-efficient clusters capable of severe gusts. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 30% - Enhanced Hail: 15% - Slight ..Smith.. 08/10/2019 Read more

No Mesoscale Discussions are in effect as of Sat Aug 10 16:39:06 UTC 2019.

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1137 AM CDT Sat Aug 10 2019 Valid 101700Z - 111200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF EASTERN NEVADA INTO FAR WEST-CENTRAL UTAH... The isolated dry thunderstorm delineation has been extended farther eastward into Idaho, where greater confidence exists for lightning atop fuels that are at least modestly receptive to fire spread. A scattered dry thunderstorm delineation was considered for parts of Oregon into Idaho, given the expected overall density of lightning. Nonetheless, wetting rains from the previous day's thunderstorm activity, combined with the expected relatively widespread coverage of heavier precipitation today, have precluded the need for a scattered dry thunderstorm area. Still, new fire ignitions are possible with strikes on the periphery of storm cores. In addition, strong to severe wind gusts may promote erratic surface conditions amidst complex terrain to potentially locally enhance fire starts or agitate ongoing fires in the absence of heavier rain, and assuming receptive fuels are present. Please see the Day 1 Convective Outlook for more details pertaining to the severe threat. Otherwise, the previous forecast remains on track. Please see below for more details. ..Squitieri.. 08/10/2019 .PREV DISCUSSION... /ISSUED 1247 AM CDT Sat Aug 10 2019/ ...Synopsis... A mid-level trough just off the northern California coast will begin to transition into an open wave and take on a negative tilt while ejecting toward Idaho today. As this occurs, a belt of enhanced mid-level flow will shift eastward toward the western Great Basin, overspreading dry areas of NV/UT/ID during peak heating hours. Meanwhile, areas of thunderstorms will once again affect portions of the Northwest, with isolated dry thunderstorm potential expected during the afternoon, evening, and overnight. ...Eastern Nevada, western Utah, and eastern Idaho... Beneath the belt of enhanced mid/upper flow, vertical mixing processes and a favorable surface gradient will favor increased surface winds within this corridor during peak heating hours. Areas of 15-25 mph south-southwesterly winds will become common amidst critically low RH values and broad areas of dry fuels in areas unaffected by recent rainfall. At this time, it appears that the greatest confidence of critical fire weather thresholds being exceeded will occur across east-central NV, far west-central UT, although locally critical fire weather can be expected as far north as eastern Idaho. ...Northern California through Washington and eastward into western Idaho for thunderstorms... The presence of cool temperatures aloft associated with the mid-level trough resulted in broad areas of wetting thunderstorms especially from central into north-central Oregon this afternoon and evening. These wetting downpours have undoubtedly altered fuel states in several areas, and widespread wetting thunderstorms are also expected to develop and migrate from south to north this afternoon and evening also. The isolated dry thunder area covers the potential for dry lightning strikes on the periphery of wetting thunderstorm cores in areas that continue to have cured fuels that can sustain fires. ...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 1137 AM CDT Sat Aug 10 2019 Valid 101700Z - 111200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF EASTERN NEVADA INTO FAR WEST-CENTRAL UTAH... The isolated dry thunderstorm delineation has been extended farther eastward into Idaho, where greater confidence exists for lightning atop fuels that are at least modestly receptive to fire spread. A scattered dry thunderstorm delineation was considered for parts of Oregon into Idaho, given the expected overall density of lightning. Nonetheless, wetting rains from the previous day's thunderstorm activity, combined with the expected relatively widespread coverage of heavier precipitation today, have precluded the need for a scattered dry thunderstorm area. Still, new fire ignitions are possible with strikes on the periphery of storm cores. In addition, strong to severe wind gusts may promote erratic surface conditions amidst complex terrain to potentially locally enhance fire starts or agitate ongoing fires in the absence of heavier rain, and assuming receptive fuels are present. Please see the Day 1 Convective Outlook for more details pertaining to the severe threat. Otherwise, the previous forecast remains on track. Please see below for more details. ..Squitieri.. 08/10/2019 .PREV DISCUSSION... /ISSUED 1247 AM CDT Sat Aug 10 2019/ ...Synopsis... A mid-level trough just off the northern California coast will begin to transition into an open wave and take on a negative tilt while ejecting toward Idaho today. As this occurs, a belt of enhanced mid-level flow will shift eastward toward the western Great Basin, overspreading dry areas of NV/UT/ID during peak heating hours. Meanwhile, areas of thunderstorms will once again affect portions of the Northwest, with isolated dry thunderstorm potential expected during the afternoon, evening, and overnight. ...Eastern Nevada, western Utah, and eastern Idaho... Beneath the belt of enhanced mid/upper flow, vertical mixing processes and a favorable surface gradient will favor increased surface winds within this corridor during peak heating hours. Areas of 15-25 mph south-southwesterly winds will become common amidst critically low RH values and broad areas of dry fuels in areas unaffected by recent rainfall. At this time, it appears that the greatest confidence of critical fire weather thresholds being exceeded will occur across east-central NV, far west-central UT, although locally critical fire weather can be expected as far north as eastern Idaho. ...Northern California through Washington and eastward into western Idaho for thunderstorms... The presence of cool temperatures aloft associated with the mid-level trough resulted in broad areas of wetting thunderstorms especially from central into north-central Oregon this afternoon and evening. These wetting downpours have undoubtedly altered fuel states in several areas, and widespread wetting thunderstorms are also expected to develop and migrate from south to north this afternoon and evening also. The isolated dry thunder area covers the potential for dry lightning strikes on the periphery of wetting thunderstorm cores in areas that continue to have cured fuels that can sustain fires. ...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 1137 AM CDT Sat Aug 10 2019 Valid 101700Z - 111200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF EASTERN NEVADA INTO FAR WEST-CENTRAL UTAH... The isolated dry thunderstorm delineation has been extended farther eastward into Idaho, where greater confidence exists for lightning atop fuels that are at least modestly receptive to fire spread. A scattered dry thunderstorm delineation was considered for parts of Oregon into Idaho, given the expected overall density of lightning. Nonetheless, wetting rains from the previous day's thunderstorm activity, combined with the expected relatively widespread coverage of heavier precipitation today, have precluded the need for a scattered dry thunderstorm area. Still, new fire ignitions are possible with strikes on the periphery of storm cores. In addition, strong to severe wind gusts may promote erratic surface conditions amidst complex terrain to potentially locally enhance fire starts or agitate ongoing fires in the absence of heavier rain, and assuming receptive fuels are present. Please see the Day 1 Convective Outlook for more details pertaining to the severe threat. Otherwise, the previous forecast remains on track. Please see below for more details. ..Squitieri.. 08/10/2019 .PREV DISCUSSION... /ISSUED 1247 AM CDT Sat Aug 10 2019/ ...Synopsis... A mid-level trough just off the northern California coast will begin to transition into an open wave and take on a negative tilt while ejecting toward Idaho today. As this occurs, a belt of enhanced mid-level flow will shift eastward toward the western Great Basin, overspreading dry areas of NV/UT/ID during peak heating hours. Meanwhile, areas of thunderstorms will once again affect portions of the Northwest, with isolated dry thunderstorm potential expected during the afternoon, evening, and overnight. ...Eastern Nevada, western Utah, and eastern Idaho... Beneath the belt of enhanced mid/upper flow, vertical mixing processes and a favorable surface gradient will favor increased surface winds within this corridor during peak heating hours. Areas of 15-25 mph south-southwesterly winds will become common amidst critically low RH values and broad areas of dry fuels in areas unaffected by recent rainfall. At this time, it appears that the greatest confidence of critical fire weather thresholds being exceeded will occur across east-central NV, far west-central UT, although locally critical fire weather can be expected as far north as eastern Idaho. ...Northern California through Washington and eastward into western Idaho for thunderstorms... The presence of cool temperatures aloft associated with the mid-level trough resulted in broad areas of wetting thunderstorms especially from central into north-central Oregon this afternoon and evening. These wetting downpours have undoubtedly altered fuel states in several areas, and widespread wetting thunderstorms are also expected to develop and migrate from south to north this afternoon and evening also. The isolated dry thunder area covers the potential for dry lightning strikes on the periphery of wetting thunderstorm cores in areas that continue to have cured fuels that can sustain fires. ...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 1137 AM CDT Sat Aug 10 2019 Valid 101700Z - 111200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF EASTERN NEVADA INTO FAR WEST-CENTRAL UTAH... The isolated dry thunderstorm delineation has been extended farther eastward into Idaho, where greater confidence exists for lightning atop fuels that are at least modestly receptive to fire spread. A scattered dry thunderstorm delineation was considered for parts of Oregon into Idaho, given the expected overall density of lightning. Nonetheless, wetting rains from the previous day's thunderstorm activity, combined with the expected relatively widespread coverage of heavier precipitation today, have precluded the need for a scattered dry thunderstorm area. Still, new fire ignitions are possible with strikes on the periphery of storm cores. In addition, strong to severe wind gusts may promote erratic surface conditions amidst complex terrain to potentially locally enhance fire starts or agitate ongoing fires in the absence of heavier rain, and assuming receptive fuels are present. Please see the Day 1 Convective Outlook for more details pertaining to the severe threat. Otherwise, the previous forecast remains on track. Please see below for more details. ..Squitieri.. 08/10/2019 .PREV DISCUSSION... /ISSUED 1247 AM CDT Sat Aug 10 2019/ ...Synopsis... A mid-level trough just off the northern California coast will begin to transition into an open wave and take on a negative tilt while ejecting toward Idaho today. As this occurs, a belt of enhanced mid-level flow will shift eastward toward the western Great Basin, overspreading dry areas of NV/UT/ID during peak heating hours. Meanwhile, areas of thunderstorms will once again affect portions of the Northwest, with isolated dry thunderstorm potential expected during the afternoon, evening, and overnight. ...Eastern Nevada, western Utah, and eastern Idaho... Beneath the belt of enhanced mid/upper flow, vertical mixing processes and a favorable surface gradient will favor increased surface winds within this corridor during peak heating hours. Areas of 15-25 mph south-southwesterly winds will become common amidst critically low RH values and broad areas of dry fuels in areas unaffected by recent rainfall. At this time, it appears that the greatest confidence of critical fire weather thresholds being exceeded will occur across east-central NV, far west-central UT, although locally critical fire weather can be expected as far north as eastern Idaho. ...Northern California through Washington and eastward into western Idaho for thunderstorms... The presence of cool temperatures aloft associated with the mid-level trough resulted in broad areas of wetting thunderstorms especially from central into north-central Oregon this afternoon and evening. These wetting downpours have undoubtedly altered fuel states in several areas, and widespread wetting thunderstorms are also expected to develop and migrate from south to north this afternoon and evening also. The isolated dry thunder area covers the potential for dry lightning strikes on the periphery of wetting thunderstorm cores in areas that continue to have cured fuels that can sustain fires. ...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 1137 AM CDT Sat Aug 10 2019 Valid 101700Z - 111200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF EASTERN NEVADA INTO FAR WEST-CENTRAL UTAH... The isolated dry thunderstorm delineation has been extended farther eastward into Idaho, where greater confidence exists for lightning atop fuels that are at least modestly receptive to fire spread. A scattered dry thunderstorm delineation was considered for parts of Oregon into Idaho, given the expected overall density of lightning. Nonetheless, wetting rains from the previous day's thunderstorm activity, combined with the expected relatively widespread coverage of heavier precipitation today, have precluded the need for a scattered dry thunderstorm area. Still, new fire ignitions are possible with strikes on the periphery of storm cores. In addition, strong to severe wind gusts may promote erratic surface conditions amidst complex terrain to potentially locally enhance fire starts or agitate ongoing fires in the absence of heavier rain, and assuming receptive fuels are present. Please see the Day 1 Convective Outlook for more details pertaining to the severe threat. Otherwise, the previous forecast remains on track. Please see below for more details. ..Squitieri.. 08/10/2019 .PREV DISCUSSION... /ISSUED 1247 AM CDT Sat Aug 10 2019/ ...Synopsis... A mid-level trough just off the northern California coast will begin to transition into an open wave and take on a negative tilt while ejecting toward Idaho today. As this occurs, a belt of enhanced mid-level flow will shift eastward toward the western Great Basin, overspreading dry areas of NV/UT/ID during peak heating hours. Meanwhile, areas of thunderstorms will once again affect portions of the Northwest, with isolated dry thunderstorm potential expected during the afternoon, evening, and overnight. ...Eastern Nevada, western Utah, and eastern Idaho... Beneath the belt of enhanced mid/upper flow, vertical mixing processes and a favorable surface gradient will favor increased surface winds within this corridor during peak heating hours. Areas of 15-25 mph south-southwesterly winds will become common amidst critically low RH values and broad areas of dry fuels in areas unaffected by recent rainfall. At this time, it appears that the greatest confidence of critical fire weather thresholds being exceeded will occur across east-central NV, far west-central UT, although locally critical fire weather can be expected as far north as eastern Idaho. ...Northern California through Washington and eastward into western Idaho for thunderstorms... The presence of cool temperatures aloft associated with the mid-level trough resulted in broad areas of wetting thunderstorms especially from central into north-central Oregon this afternoon and evening. These wetting downpours have undoubtedly altered fuel states in several areas, and widespread wetting thunderstorms are also expected to develop and migrate from south to north this afternoon and evening also. The isolated dry thunder area covers the potential for dry lightning strikes on the periphery of wetting thunderstorm cores in areas that continue to have cured fuels that can sustain fires. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Sat Aug 10 2019 Valid 101630Z - 111200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF ID/MT/WY AND EASTERN NC... ...SUMMARY... Scattered severe thunderstorms with large hail and damaging wind gusts are most likely across parts of Idaho, Montana, Wyoming, and eastern North Carolina. The severe threat should be greatest during the late afternoon to early evening. ...Northwest... A closed mid-level low near the CA/OR coastal border will gradually evolve into an open wave while ejecting towards the OR/ID border through tonight, as other subtle speed maxima rotate around the eastern periphery of the low. A plume of weak to moderate buoyancy will develop at peak heating, arcing from OR/ID east across the northern Rockies and High Plains where scattered thunderstorms will likely form by late afternoon. Greatest effective shear should be centered across southern MT where weak low-level easterlies will be present beneath southwesterlies aloft that strengthen with height. This should yield an elongated, straight-line hodograph favorable for several splitting supercell structures. Large hail and severe wind gusts will be the primary hazards. Relatively high LCLs may limit the overall tornado threat, but brief ones are possible where 50s surface dew points can be sustained. ...Eastern NC... Sea breeze circulations along with a weakly convergent quasi-stationary front should be the focus for isolated to perhaps scattered thunderstorm development during the next few hours. Rich boundary-layer moisture characterized by low to mid 70s surface dew points exists over coastal southern NC into SC which will result in a confined corridor of MLCAPE in excess of 2000 J/kg. A few cells should briefly organize amid 30-40 kt 500-mb west-northwesterlies. Isolated large hail and damaging winds are anticipated. A marginal severe threat may persist into tonight amid weak low-level warm advection. ...Central High Plains to IA vicinity... A messy/low confidence scenario is anticipated through tonight with multiple MCVs and lingering cloud debris across the region. Forcing for ascent will likely persist across the Mid-MO Valley in a zone of low-level warm advection. Pockets of greater surface heating are apparent within cloud breaks into IA which combined with low-level moistening should support weak to moderate MLCAPE. Moderate enlargement/curvature to the low-level hodograph may foster a conditional brief tornado/locally damaging wind risk. Relatively warm profiles aloft and weak mid-level lapse rates will be unfavorable for large hail. Otherwise, scattered late afternoon storms should develop off the southern Rockies across eastern CO. Modest effective shear may be adequate to support multicell clustering as convection impinges on substantially greater buoyancy across KS/NE. Low-level warm advection will also increase across KS tonight in response to a nocturnal low-level jet, when more widespread convection is expected in the form of multiple clusters. Given the shear profiles, convection may be only weakly organized and slow-moving. But a threat for locally severe wind gusts should exist given heavy precipitation loading amid PW in excess of 2 inches. ..Grams/Dean.. 08/10/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Sat Aug 10 2019 Valid 101630Z - 111200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF ID/MT/WY AND EASTERN NC... ...SUMMARY... Scattered severe thunderstorms with large hail and damaging wind gusts are most likely across parts of Idaho, Montana, Wyoming, and eastern North Carolina. The severe threat should be greatest during the late afternoon to early evening. ...Northwest... A closed mid-level low near the CA/OR coastal border will gradually evolve into an open wave while ejecting towards the OR/ID border through tonight, as other subtle speed maxima rotate around the eastern periphery of the low. A plume of weak to moderate buoyancy will develop at peak heating, arcing from OR/ID east across the northern Rockies and High Plains where scattered thunderstorms will likely form by late afternoon. Greatest effective shear should be centered across southern MT where weak low-level easterlies will be present beneath southwesterlies aloft that strengthen with height. This should yield an elongated, straight-line hodograph favorable for several splitting supercell structures. Large hail and severe wind gusts will be the primary hazards. Relatively high LCLs may limit the overall tornado threat, but brief ones are possible where 50s surface dew points can be sustained. ...Eastern NC... Sea breeze circulations along with a weakly convergent quasi-stationary front should be the focus for isolated to perhaps scattered thunderstorm development during the next few hours. Rich boundary-layer moisture characterized by low to mid 70s surface dew points exists over coastal southern NC into SC which will result in a confined corridor of MLCAPE in excess of 2000 J/kg. A few cells should briefly organize amid 30-40 kt 500-mb west-northwesterlies. Isolated large hail and damaging winds are anticipated. A marginal severe threat may persist into tonight amid weak low-level warm advection. ...Central High Plains to IA vicinity... A messy/low confidence scenario is anticipated through tonight with multiple MCVs and lingering cloud debris across the region. Forcing for ascent will likely persist across the Mid-MO Valley in a zone of low-level warm advection. Pockets of greater surface heating are apparent within cloud breaks into IA which combined with low-level moistening should support weak to moderate MLCAPE. Moderate enlargement/curvature to the low-level hodograph may foster a conditional brief tornado/locally damaging wind risk. Relatively warm profiles aloft and weak mid-level lapse rates will be unfavorable for large hail. Otherwise, scattered late afternoon storms should develop off the southern Rockies across eastern CO. Modest effective shear may be adequate to support multicell clustering as convection impinges on substantially greater buoyancy across KS/NE. Low-level warm advection will also increase across KS tonight in response to a nocturnal low-level jet, when more widespread convection is expected in the form of multiple clusters. Given the shear profiles, convection may be only weakly organized and slow-moving. But a threat for locally severe wind gusts should exist given heavy precipitation loading amid PW in excess of 2 inches. ..Grams/Dean.. 08/10/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Sat Aug 10 2019 Valid 101630Z - 111200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF ID/MT/WY AND EASTERN NC... ...SUMMARY... Scattered severe thunderstorms with large hail and damaging wind gusts are most likely across parts of Idaho, Montana, Wyoming, and eastern North Carolina. The severe threat should be greatest during the late afternoon to early evening. ...Northwest... A closed mid-level low near the CA/OR coastal border will gradually evolve into an open wave while ejecting towards the OR/ID border through tonight, as other subtle speed maxima rotate around the eastern periphery of the low. A plume of weak to moderate buoyancy will develop at peak heating, arcing from OR/ID east across the northern Rockies and High Plains where scattered thunderstorms will likely form by late afternoon. Greatest effective shear should be centered across southern MT where weak low-level easterlies will be present beneath southwesterlies aloft that strengthen with height. This should yield an elongated, straight-line hodograph favorable for several splitting supercell structures. Large hail and severe wind gusts will be the primary hazards. Relatively high LCLs may limit the overall tornado threat, but brief ones are possible where 50s surface dew points can be sustained. ...Eastern NC... Sea breeze circulations along with a weakly convergent quasi-stationary front should be the focus for isolated to perhaps scattered thunderstorm development during the next few hours. Rich boundary-layer moisture characterized by low to mid 70s surface dew points exists over coastal southern NC into SC which will result in a confined corridor of MLCAPE in excess of 2000 J/kg. A few cells should briefly organize amid 30-40 kt 500-mb west-northwesterlies. Isolated large hail and damaging winds are anticipated. A marginal severe threat may persist into tonight amid weak low-level warm advection. ...Central High Plains to IA vicinity... A messy/low confidence scenario is anticipated through tonight with multiple MCVs and lingering cloud debris across the region. Forcing for ascent will likely persist across the Mid-MO Valley in a zone of low-level warm advection. Pockets of greater surface heating are apparent within cloud breaks into IA which combined with low-level moistening should support weak to moderate MLCAPE. Moderate enlargement/curvature to the low-level hodograph may foster a conditional brief tornado/locally damaging wind risk. Relatively warm profiles aloft and weak mid-level lapse rates will be unfavorable for large hail. Otherwise, scattered late afternoon storms should develop off the southern Rockies across eastern CO. Modest effective shear may be adequate to support multicell clustering as convection impinges on substantially greater buoyancy across KS/NE. Low-level warm advection will also increase across KS tonight in response to a nocturnal low-level jet, when more widespread convection is expected in the form of multiple clusters. Given the shear profiles, convection may be only weakly organized and slow-moving. But a threat for locally severe wind gusts should exist given heavy precipitation loading amid PW in excess of 2 inches. ..Grams/Dean.. 08/10/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Sat Aug 10 2019 Valid 101630Z - 111200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF ID/MT/WY AND EASTERN NC... ...SUMMARY... Scattered severe thunderstorms with large hail and damaging wind gusts are most likely across parts of Idaho, Montana, Wyoming, and eastern North Carolina. The severe threat should be greatest during the late afternoon to early evening. ...Northwest... A closed mid-level low near the CA/OR coastal border will gradually evolve into an open wave while ejecting towards the OR/ID border through tonight, as other subtle speed maxima rotate around the eastern periphery of the low. A plume of weak to moderate buoyancy will develop at peak heating, arcing from OR/ID east across the northern Rockies and High Plains where scattered thunderstorms will likely form by late afternoon. Greatest effective shear should be centered across southern MT where weak low-level easterlies will be present beneath southwesterlies aloft that strengthen with height. This should yield an elongated, straight-line hodograph favorable for several splitting supercell structures. Large hail and severe wind gusts will be the primary hazards. Relatively high LCLs may limit the overall tornado threat, but brief ones are possible where 50s surface dew points can be sustained. ...Eastern NC... Sea breeze circulations along with a weakly convergent quasi-stationary front should be the focus for isolated to perhaps scattered thunderstorm development during the next few hours. Rich boundary-layer moisture characterized by low to mid 70s surface dew points exists over coastal southern NC into SC which will result in a confined corridor of MLCAPE in excess of 2000 J/kg. A few cells should briefly organize amid 30-40 kt 500-mb west-northwesterlies. Isolated large hail and damaging winds are anticipated. A marginal severe threat may persist into tonight amid weak low-level warm advection. ...Central High Plains to IA vicinity... A messy/low confidence scenario is anticipated through tonight with multiple MCVs and lingering cloud debris across the region. Forcing for ascent will likely persist across the Mid-MO Valley in a zone of low-level warm advection. Pockets of greater surface heating are apparent within cloud breaks into IA which combined with low-level moistening should support weak to moderate MLCAPE. Moderate enlargement/curvature to the low-level hodograph may foster a conditional brief tornado/locally damaging wind risk. Relatively warm profiles aloft and weak mid-level lapse rates will be unfavorable for large hail. Otherwise, scattered late afternoon storms should develop off the southern Rockies across eastern CO. Modest effective shear may be adequate to support multicell clustering as convection impinges on substantially greater buoyancy across KS/NE. Low-level warm advection will also increase across KS tonight in response to a nocturnal low-level jet, when more widespread convection is expected in the form of multiple clusters. Given the shear profiles, convection may be only weakly organized and slow-moving. But a threat for locally severe wind gusts should exist given heavy precipitation loading amid PW in excess of 2 inches. ..Grams/Dean.. 08/10/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 AM CDT Sat Aug 10 2019 Valid 101300Z - 111200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO THIS EVENING FOR PARTS OF OR...ID...MT AND NC... ...SUMMARY... Severe storms producing large hail and locally damaging wind gusts are expected from eastern Oregon into western and southern Montana during the afternoon and evening. A cluster of storms, some severe, is also expected over eastern North Carolina during the afternoon. Other isolated activity is likely from the Black Hills into the central High Plains with marginal hail and wind. ...Northern Rockies this afternoon/evening... A closed midlevel low near the northern CA coast this morning will evolve gradually into an open wave while ejecting northeastward toward ID by tonight, as other subtle speed maxima rotate around the eastern periphery of the low. Northeast of the ongoing convection across northern CA, surface heating beneath relatively cool midlevel temperatures will contribute to MLCAPE of 500-1000 J/kg, within a corridor of deep-layer southerly shear of 35-50 kt. Scattered thunderstorm development is likely in the zone of ascent immediately northeast of the ejecting trough, where a few storms could produce damaging outflow winds and isolated large hail. Farther northeast into ID and MT, broken bands of convection are expected this afternoon as surface heating over the high terrain coincides with ascent accompanying a lead speed max aloft. Storm development should extend eastward across southern MT through the afternoon. Surface heating and boundary-layer dewpoints in the 50s beneath steep midlevel lapse rates will drive moderate buoyancy (MLCAPE up to 1500 J/kg). Meanwhile, low-level easterly flow beneath southwesterly flow aloft will result in long hodographs favoring supercells. The stronger storms will be capable of producing large hail and damaging winds, primarily from mid afternoon into this evening. ...Eastern NC this afternoon... A quasi-stationary front just inland from the NC coast, in conjunction with local sea breeze circulations, will help focus thunderstorm development this afternoon. Rich low-level moisture (boundary-layer dewpoints in the mid-upper 70s) along the coast and strong surface heating inland along the boundary will contribute to MLCAPE in excess of 2000 J/kg. West-northwesterly flow aloft and any sea breeze augmentation of near-surface, south-southeasterly flow will result in sufficient vertical shear for organized clusters and/or some supercell structures, with the potential to produce damaging winds and isolated large hail. ...Central Plains vicinity this afternoon into tonight... A messy scenario is unfolding across CO/NE/IA/KS today into tonight with multiple MCVs, ongoing convection, and cloud debris within the northeast extent of the southern Rockies monsoonal moisture plume. Forcing for ascent will likely persist across IA in a zone of low-level warm advection, and some low-level moistening and destabilization is expected. However, relatively warm profiles aloft and modest lapse rates do not appear favorable for large hail, and it is not clear if storms will be rooted clearly at the surface where low-level shear/hodograph curvature will be stronger. Farther west, forcing for ascent will be weak and confined to a diffuse surface boundary into southeast NE, which could focus isolated strong thunderstorm development this evening. A few diurnal storms are expected in the developing upslope flow regime by this evening across eastern CO and western KS. Farther east, clouds will likely slow surface heating and a lingering EML will be warm enough to maintain some convective inhibition through much of the afternoon. Low-level warm advection will increase across KS tonight in response to a weak nocturnal low-level jet, when more widespread convection is expected in one or more clusters. Lingering steep low-midlevel lapse rates and PW in excess of 2 inches will support some threat for isolated strong/damaging winds with heavy precipitation loading, and perhaps isolated marginally severe hail. ..Thompson/Kerr.. 08/10/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 AM CDT Sat Aug 10 2019 Valid 101300Z - 111200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO THIS EVENING FOR PARTS OF OR...ID...MT AND NC... ...SUMMARY... Severe storms producing large hail and locally damaging wind gusts are expected from eastern Oregon into western and southern Montana during the afternoon and evening. A cluster of storms, some severe, is also expected over eastern North Carolina during the afternoon. Other isolated activity is likely from the Black Hills into the central High Plains with marginal hail and wind. ...Northern Rockies this afternoon/evening... A closed midlevel low near the northern CA coast this morning will evolve gradually into an open wave while ejecting northeastward toward ID by tonight, as other subtle speed maxima rotate around the eastern periphery of the low. Northeast of the ongoing convection across northern CA, surface heating beneath relatively cool midlevel temperatures will contribute to MLCAPE of 500-1000 J/kg, within a corridor of deep-layer southerly shear of 35-50 kt. Scattered thunderstorm development is likely in the zone of ascent immediately northeast of the ejecting trough, where a few storms could produce damaging outflow winds and isolated large hail. Farther northeast into ID and MT, broken bands of convection are expected this afternoon as surface heating over the high terrain coincides with ascent accompanying a lead speed max aloft. Storm development should extend eastward across southern MT through the afternoon. Surface heating and boundary-layer dewpoints in the 50s beneath steep midlevel lapse rates will drive moderate buoyancy (MLCAPE up to 1500 J/kg). Meanwhile, low-level easterly flow beneath southwesterly flow aloft will result in long hodographs favoring supercells. The stronger storms will be capable of producing large hail and damaging winds, primarily from mid afternoon into this evening. ...Eastern NC this afternoon... A quasi-stationary front just inland from the NC coast, in conjunction with local sea breeze circulations, will help focus thunderstorm development this afternoon. Rich low-level moisture (boundary-layer dewpoints in the mid-upper 70s) along the coast and strong surface heating inland along the boundary will contribute to MLCAPE in excess of 2000 J/kg. West-northwesterly flow aloft and any sea breeze augmentation of near-surface, south-southeasterly flow will result in sufficient vertical shear for organized clusters and/or some supercell structures, with the potential to produce damaging winds and isolated large hail. ...Central Plains vicinity this afternoon into tonight... A messy scenario is unfolding across CO/NE/IA/KS today into tonight with multiple MCVs, ongoing convection, and cloud debris within the northeast extent of the southern Rockies monsoonal moisture plume. Forcing for ascent will likely persist across IA in a zone of low-level warm advection, and some low-level moistening and destabilization is expected. However, relatively warm profiles aloft and modest lapse rates do not appear favorable for large hail, and it is not clear if storms will be rooted clearly at the surface where low-level shear/hodograph curvature will be stronger. Farther west, forcing for ascent will be weak and confined to a diffuse surface boundary into southeast NE, which could focus isolated strong thunderstorm development this evening. A few diurnal storms are expected in the developing upslope flow regime by this evening across eastern CO and western KS. Farther east, clouds will likely slow surface heating and a lingering EML will be warm enough to maintain some convective inhibition through much of the afternoon. Low-level warm advection will increase across KS tonight in response to a weak nocturnal low-level jet, when more widespread convection is expected in one or more clusters. Lingering steep low-midlevel lapse rates and PW in excess of 2 inches will support some threat for isolated strong/damaging winds with heavy precipitation loading, and perhaps isolated marginally severe hail. ..Thompson/Kerr.. 08/10/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 AM CDT Sat Aug 10 2019 Valid 101300Z - 111200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO THIS EVENING FOR PARTS OF OR...ID...MT AND NC... ...SUMMARY... Severe storms producing large hail and locally damaging wind gusts are expected from eastern Oregon into western and southern Montana during the afternoon and evening. A cluster of storms, some severe, is also expected over eastern North Carolina during the afternoon. Other isolated activity is likely from the Black Hills into the central High Plains with marginal hail and wind. ...Northern Rockies this afternoon/evening... A closed midlevel low near the northern CA coast this morning will evolve gradually into an open wave while ejecting northeastward toward ID by tonight, as other subtle speed maxima rotate around the eastern periphery of the low. Northeast of the ongoing convection across northern CA, surface heating beneath relatively cool midlevel temperatures will contribute to MLCAPE of 500-1000 J/kg, within a corridor of deep-layer southerly shear of 35-50 kt. Scattered thunderstorm development is likely in the zone of ascent immediately northeast of the ejecting trough, where a few storms could produce damaging outflow winds and isolated large hail. Farther northeast into ID and MT, broken bands of convection are expected this afternoon as surface heating over the high terrain coincides with ascent accompanying a lead speed max aloft. Storm development should extend eastward across southern MT through the afternoon. Surface heating and boundary-layer dewpoints in the 50s beneath steep midlevel lapse rates will drive moderate buoyancy (MLCAPE up to 1500 J/kg). Meanwhile, low-level easterly flow beneath southwesterly flow aloft will result in long hodographs favoring supercells. The stronger storms will be capable of producing large hail and damaging winds, primarily from mid afternoon into this evening. ...Eastern NC this afternoon... A quasi-stationary front just inland from the NC coast, in conjunction with local sea breeze circulations, will help focus thunderstorm development this afternoon. Rich low-level moisture (boundary-layer dewpoints in the mid-upper 70s) along the coast and strong surface heating inland along the boundary will contribute to MLCAPE in excess of 2000 J/kg. West-northwesterly flow aloft and any sea breeze augmentation of near-surface, south-southeasterly flow will result in sufficient vertical shear for organized clusters and/or some supercell structures, with the potential to produce damaging winds and isolated large hail. ...Central Plains vicinity this afternoon into tonight... A messy scenario is unfolding across CO/NE/IA/KS today into tonight with multiple MCVs, ongoing convection, and cloud debris within the northeast extent of the southern Rockies monsoonal moisture plume. Forcing for ascent will likely persist across IA in a zone of low-level warm advection, and some low-level moistening and destabilization is expected. However, relatively warm profiles aloft and modest lapse rates do not appear favorable for large hail, and it is not clear if storms will be rooted clearly at the surface where low-level shear/hodograph curvature will be stronger. Farther west, forcing for ascent will be weak and confined to a diffuse surface boundary into southeast NE, which could focus isolated strong thunderstorm development this evening. A few diurnal storms are expected in the developing upslope flow regime by this evening across eastern CO and western KS. Farther east, clouds will likely slow surface heating and a lingering EML will be warm enough to maintain some convective inhibition through much of the afternoon. Low-level warm advection will increase across KS tonight in response to a weak nocturnal low-level jet, when more widespread convection is expected in one or more clusters. Lingering steep low-midlevel lapse rates and PW in excess of 2 inches will support some threat for isolated strong/damaging winds with heavy precipitation loading, and perhaps isolated marginally severe hail. ..Thompson/Kerr.. 08/10/2019 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0342 AM CDT Sat Aug 10 2019 Valid 131200Z - 181200Z ...DISCUSSION... Model consensus is that the synoptic upper pattern will trend to a quasi-zonal regime over most of the northern tier states days 4-5 before another upper trough amplifies over the Pacific Northwest and moves into the northern Plains in the 6-7 day time frame. The richer moisture will be shunted south of the stronger winds aloft by a cold front advancing southeast through the OH Valley region days 4-5. However, by days 6-7 moisture will gradually return through the Plains downstream from an approaching northern stream trough. While at least a modest threat for severe weather may exist along front from the Middle Atlantic into the southern portion of the OH Valley day 4, and then the northern Plains days 6-7, overall predictability with this pattern remains low. Read more