Severe Storms

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 AM CDT Mon Aug 05 2024 Valid 051300Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER OHIO VALLEY INTO NEW ENGLAND...ACROSS PORTIONS OF THE UPPER MIDWEST...AND FROM NORTHERN FLORIDA INTO SOUTHERN GEORGIA AND SOUTHEAST SOUTH CAROLINA... ...SUMMARY... Severe thunderstorms are possible today and tonight from the Upper Ohio Valley into New England, across portions of the Upper Midwest, and from northern Florida into southern Georgia and southeast South Carolina. ...Synopsis... With height falls well underway on its northern rim -- over the northern Rockies -- the Four Corners regional anticyclone has become ore zonally elongated, with a shift/reformation of the associated 500-mb high over the San Juan Mountains or adjoining San Luis Valley. Through the period, associated ridging will extend east-southeastward across southern KS to AR, west-southwestward over the LAS area to southern CA, and will rebuild northwestward over the northern Rockies. The latter will occur as a series of closely spaced shortwave perturbations -- apparent in moisture-channel imagery from the western Dakotas to north-central MT -- shift eastward across the Dakotas to MN by 00Z. These features then should cross WI and Lake Michigan tonight. Just west of the ridge, a weak shortwave trough now over the central/northern Sierra should move north-northeastward toward the northern Rockies through the day. Farther east, a strong shortwave trough was evident over northern ON north of Lake Superior, in the southwest quadrant of a vast cyclone covering most of eastern Canada. This trough should move east-southeastward across southernmost QC to ME by 06Z, then over the Canadian Maritimes. At the surface, 11Z analysis showed a wavy, slow-moving (mostly stationary) frontal zone from central New England to a weak low over southern Lake Huron, across southern Lake Michigan and northern IA, to another low over south-central SD between PIR-VTN, then across central WY. As the mid/upper shortwave trough approaches and grazes the area, the eastern part of the front should move slowly southeastward across the Lower Great Lakes, Adirondacks, White Mountains and much of ME by 00Z. The trailing part should drift southward into northern parts of OH/IN/IL, then decelerate/stall overnight. The SD low should ripple east-southeastward along the front and across the Siouxland region by 00Z, then over northern IA tonight. The trailing cold front from there should extend across eastern NE, northwestern KS and southeastern CO by 00Z, stalling overnight over southwestern KS and southeastern CO in response to cyclogenesis near LAA. ...FL/GA/SC -- Hurricane Debby... Hurricane Debby has made landfall in the FL "Big Bend" coastal area, and the center is forecast by NHC to proceed slowly northeastward over the FL/GA line through the period. See SPC Tornado Watch 596 and related mesoscale discussions for near-term potential. Refer to latest NHC advisories for forecast track/intensity of Debby, and tropical watches/warnings. The existing tornado potential southeast of center largely is expected to translate along with Debby, while expanding northeastward to the Atlantic Coast of northeastern FL and GA, as favorable low-level theta-e advection from the Atlantic destabilizes the nearshore airmass there. An extensive area of precip northeast through north of center should be maintained, substantially restricting instability over northwestern FL and southwestern/ south-central GA to the left of the forecast center track, and reinforcing the baroclinic gradient there. That should act as a buoyancy-limiting northwestern bound to the supercell/tornado threat. Meanwhile, as low-level flow veers further on the FL West Coast through the remainder of this morning, and weaker lift with a more skeletal convective structure moves across the area south of center, supercell/tornado potential will diminish there. The optimal CAPE/shear parameter space should shift through northern FL into southeastern GA today, while expanding along the GA and eventually SC Coast later today through tonight. ...Northeast and Great Lakes to upper Mississippi Valley... Through tonight, multiple rounds of strong to severe convection are possible across this lengthy but relatively narrow corridor near the front, through tonight. Damaging winds will be the main concern in the Northeast, though enough low-level shear/hodograph enlargement exists in forecast soundings across parts of northern New England to support some supercell potential. Meanwhile, supercells with large hail and a tornado threat may develop before dark or in early evening between southern MN and southern Lake Michigan. Activity overall should evolve upscale to a more clustered, wind-driven threat with time, lasting later in the evening over western areas. Surface-based development is likely to occur earlier in the eastern "slight risk" area -- from midday through this afternoon, as peripheral mass response to the Canadian perturbation increases low-level convergence and tightens the height gradient aloft. The latter will increase deep shear, though nearly unidirectional wind profiles should persist over the corridor, except in parts of north-central New England and northern IA/southern MN, each to the east of frontal-wave lows. Strong diurnal warming will occur in conjunction with favorable low-level moisture, with surface dewpoints commonly in the mid/upper 60s from OH eastward and low 70s from northern IN across the upper Mississippi Valley. This should yield peak/preconvective MLCAPE ranging from around 500-1500 J/kg over the Northeast -- where midlevel lapse rates will be weaker -- to 2000-3000 J/kg in a narrow corridor near the front from northern OH to the IA/MN border vicinity. However, capping will be stronger over the IA/MN/WI part of the front, and diurnal development/ coverage accessing the greatest surface-based buoyancy is more uncertain than evening/overnight severe hail/gust potential near and north of the front. ...Northern Rockies and vicinity... Isolated to scattered thunderstorms are expected to develop this afternoon and evening over much of ID into western MT, as modest large-scale ascent preceding the shortwave trough spreads across diurnally heated higher elevations. Development will be supported further by at least marginally favorable moisture, represented by lower-elevation surface dewpoints now in the upper 40s to low 60s F, and not expected to dry very much via mixing through early/mid afternoon. Still, heating/mixing should be strong enough to build steep low/middle-level lapse rates and "inverted-v" thermodynamic profiles supporting strong/isolated severe gusts, Some of this activity also may take the form of dry thunderstorms, especially in eastern areas -- see SPC Fire Weather products for more on that concern. ..Edwards/Grams.. 08/05/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 AM CDT Mon Aug 05 2024 Valid 051300Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER OHIO VALLEY INTO NEW ENGLAND...ACROSS PORTIONS OF THE UPPER MIDWEST...AND FROM NORTHERN FLORIDA INTO SOUTHERN GEORGIA AND SOUTHEAST SOUTH CAROLINA... ...SUMMARY... Severe thunderstorms are possible today and tonight from the Upper Ohio Valley into New England, across portions of the Upper Midwest, and from northern Florida into southern Georgia and southeast South Carolina. ...Synopsis... With height falls well underway on its northern rim -- over the northern Rockies -- the Four Corners regional anticyclone has become ore zonally elongated, with a shift/reformation of the associated 500-mb high over the San Juan Mountains or adjoining San Luis Valley. Through the period, associated ridging will extend east-southeastward across southern KS to AR, west-southwestward over the LAS area to southern CA, and will rebuild northwestward over the northern Rockies. The latter will occur as a series of closely spaced shortwave perturbations -- apparent in moisture-channel imagery from the western Dakotas to north-central MT -- shift eastward across the Dakotas to MN by 00Z. These features then should cross WI and Lake Michigan tonight. Just west of the ridge, a weak shortwave trough now over the central/northern Sierra should move north-northeastward toward the northern Rockies through the day. Farther east, a strong shortwave trough was evident over northern ON north of Lake Superior, in the southwest quadrant of a vast cyclone covering most of eastern Canada. This trough should move east-southeastward across southernmost QC to ME by 06Z, then over the Canadian Maritimes. At the surface, 11Z analysis showed a wavy, slow-moving (mostly stationary) frontal zone from central New England to a weak low over southern Lake Huron, across southern Lake Michigan and northern IA, to another low over south-central SD between PIR-VTN, then across central WY. As the mid/upper shortwave trough approaches and grazes the area, the eastern part of the front should move slowly southeastward across the Lower Great Lakes, Adirondacks, White Mountains and much of ME by 00Z. The trailing part should drift southward into northern parts of OH/IN/IL, then decelerate/stall overnight. The SD low should ripple east-southeastward along the front and across the Siouxland region by 00Z, then over northern IA tonight. The trailing cold front from there should extend across eastern NE, northwestern KS and southeastern CO by 00Z, stalling overnight over southwestern KS and southeastern CO in response to cyclogenesis near LAA. ...FL/GA/SC -- Hurricane Debby... Hurricane Debby has made landfall in the FL "Big Bend" coastal area, and the center is forecast by NHC to proceed slowly northeastward over the FL/GA line through the period. See SPC Tornado Watch 596 and related mesoscale discussions for near-term potential. Refer to latest NHC advisories for forecast track/intensity of Debby, and tropical watches/warnings. The existing tornado potential southeast of center largely is expected to translate along with Debby, while expanding northeastward to the Atlantic Coast of northeastern FL and GA, as favorable low-level theta-e advection from the Atlantic destabilizes the nearshore airmass there. An extensive area of precip northeast through north of center should be maintained, substantially restricting instability over northwestern FL and southwestern/ south-central GA to the left of the forecast center track, and reinforcing the baroclinic gradient there. That should act as a buoyancy-limiting northwestern bound to the supercell/tornado threat. Meanwhile, as low-level flow veers further on the FL West Coast through the remainder of this morning, and weaker lift with a more skeletal convective structure moves across the area south of center, supercell/tornado potential will diminish there. The optimal CAPE/shear parameter space should shift through northern FL into southeastern GA today, while expanding along the GA and eventually SC Coast later today through tonight. ...Northeast and Great Lakes to upper Mississippi Valley... Through tonight, multiple rounds of strong to severe convection are possible across this lengthy but relatively narrow corridor near the front, through tonight. Damaging winds will be the main concern in the Northeast, though enough low-level shear/hodograph enlargement exists in forecast soundings across parts of northern New England to support some supercell potential. Meanwhile, supercells with large hail and a tornado threat may develop before dark or in early evening between southern MN and southern Lake Michigan. Activity overall should evolve upscale to a more clustered, wind-driven threat with time, lasting later in the evening over western areas. Surface-based development is likely to occur earlier in the eastern "slight risk" area -- from midday through this afternoon, as peripheral mass response to the Canadian perturbation increases low-level convergence and tightens the height gradient aloft. The latter will increase deep shear, though nearly unidirectional wind profiles should persist over the corridor, except in parts of north-central New England and northern IA/southern MN, each to the east of frontal-wave lows. Strong diurnal warming will occur in conjunction with favorable low-level moisture, with surface dewpoints commonly in the mid/upper 60s from OH eastward and low 70s from northern IN across the upper Mississippi Valley. This should yield peak/preconvective MLCAPE ranging from around 500-1500 J/kg over the Northeast -- where midlevel lapse rates will be weaker -- to 2000-3000 J/kg in a narrow corridor near the front from northern OH to the IA/MN border vicinity. However, capping will be stronger over the IA/MN/WI part of the front, and diurnal development/ coverage accessing the greatest surface-based buoyancy is more uncertain than evening/overnight severe hail/gust potential near and north of the front. ...Northern Rockies and vicinity... Isolated to scattered thunderstorms are expected to develop this afternoon and evening over much of ID into western MT, as modest large-scale ascent preceding the shortwave trough spreads across diurnally heated higher elevations. Development will be supported further by at least marginally favorable moisture, represented by lower-elevation surface dewpoints now in the upper 40s to low 60s F, and not expected to dry very much via mixing through early/mid afternoon. Still, heating/mixing should be strong enough to build steep low/middle-level lapse rates and "inverted-v" thermodynamic profiles supporting strong/isolated severe gusts, Some of this activity also may take the form of dry thunderstorms, especially in eastern areas -- see SPC Fire Weather products for more on that concern. ..Edwards/Grams.. 08/05/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 AM CDT Mon Aug 05 2024 Valid 051300Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER OHIO VALLEY INTO NEW ENGLAND...ACROSS PORTIONS OF THE UPPER MIDWEST...AND FROM NORTHERN FLORIDA INTO SOUTHERN GEORGIA AND SOUTHEAST SOUTH CAROLINA... ...SUMMARY... Severe thunderstorms are possible today and tonight from the Upper Ohio Valley into New England, across portions of the Upper Midwest, and from northern Florida into southern Georgia and southeast South Carolina. ...Synopsis... With height falls well underway on its northern rim -- over the northern Rockies -- the Four Corners regional anticyclone has become ore zonally elongated, with a shift/reformation of the associated 500-mb high over the San Juan Mountains or adjoining San Luis Valley. Through the period, associated ridging will extend east-southeastward across southern KS to AR, west-southwestward over the LAS area to southern CA, and will rebuild northwestward over the northern Rockies. The latter will occur as a series of closely spaced shortwave perturbations -- apparent in moisture-channel imagery from the western Dakotas to north-central MT -- shift eastward across the Dakotas to MN by 00Z. These features then should cross WI and Lake Michigan tonight. Just west of the ridge, a weak shortwave trough now over the central/northern Sierra should move north-northeastward toward the northern Rockies through the day. Farther east, a strong shortwave trough was evident over northern ON north of Lake Superior, in the southwest quadrant of a vast cyclone covering most of eastern Canada. This trough should move east-southeastward across southernmost QC to ME by 06Z, then over the Canadian Maritimes. At the surface, 11Z analysis showed a wavy, slow-moving (mostly stationary) frontal zone from central New England to a weak low over southern Lake Huron, across southern Lake Michigan and northern IA, to another low over south-central SD between PIR-VTN, then across central WY. As the mid/upper shortwave trough approaches and grazes the area, the eastern part of the front should move slowly southeastward across the Lower Great Lakes, Adirondacks, White Mountains and much of ME by 00Z. The trailing part should drift southward into northern parts of OH/IN/IL, then decelerate/stall overnight. The SD low should ripple east-southeastward along the front and across the Siouxland region by 00Z, then over northern IA tonight. The trailing cold front from there should extend across eastern NE, northwestern KS and southeastern CO by 00Z, stalling overnight over southwestern KS and southeastern CO in response to cyclogenesis near LAA. ...FL/GA/SC -- Hurricane Debby... Hurricane Debby has made landfall in the FL "Big Bend" coastal area, and the center is forecast by NHC to proceed slowly northeastward over the FL/GA line through the period. See SPC Tornado Watch 596 and related mesoscale discussions for near-term potential. Refer to latest NHC advisories for forecast track/intensity of Debby, and tropical watches/warnings. The existing tornado potential southeast of center largely is expected to translate along with Debby, while expanding northeastward to the Atlantic Coast of northeastern FL and GA, as favorable low-level theta-e advection from the Atlantic destabilizes the nearshore airmass there. An extensive area of precip northeast through north of center should be maintained, substantially restricting instability over northwestern FL and southwestern/ south-central GA to the left of the forecast center track, and reinforcing the baroclinic gradient there. That should act as a buoyancy-limiting northwestern bound to the supercell/tornado threat. Meanwhile, as low-level flow veers further on the FL West Coast through the remainder of this morning, and weaker lift with a more skeletal convective structure moves across the area south of center, supercell/tornado potential will diminish there. The optimal CAPE/shear parameter space should shift through northern FL into southeastern GA today, while expanding along the GA and eventually SC Coast later today through tonight. ...Northeast and Great Lakes to upper Mississippi Valley... Through tonight, multiple rounds of strong to severe convection are possible across this lengthy but relatively narrow corridor near the front, through tonight. Damaging winds will be the main concern in the Northeast, though enough low-level shear/hodograph enlargement exists in forecast soundings across parts of northern New England to support some supercell potential. Meanwhile, supercells with large hail and a tornado threat may develop before dark or in early evening between southern MN and southern Lake Michigan. Activity overall should evolve upscale to a more clustered, wind-driven threat with time, lasting later in the evening over western areas. Surface-based development is likely to occur earlier in the eastern "slight risk" area -- from midday through this afternoon, as peripheral mass response to the Canadian perturbation increases low-level convergence and tightens the height gradient aloft. The latter will increase deep shear, though nearly unidirectional wind profiles should persist over the corridor, except in parts of north-central New England and northern IA/southern MN, each to the east of frontal-wave lows. Strong diurnal warming will occur in conjunction with favorable low-level moisture, with surface dewpoints commonly in the mid/upper 60s from OH eastward and low 70s from northern IN across the upper Mississippi Valley. This should yield peak/preconvective MLCAPE ranging from around 500-1500 J/kg over the Northeast -- where midlevel lapse rates will be weaker -- to 2000-3000 J/kg in a narrow corridor near the front from northern OH to the IA/MN border vicinity. However, capping will be stronger over the IA/MN/WI part of the front, and diurnal development/ coverage accessing the greatest surface-based buoyancy is more uncertain than evening/overnight severe hail/gust potential near and north of the front. ...Northern Rockies and vicinity... Isolated to scattered thunderstorms are expected to develop this afternoon and evening over much of ID into western MT, as modest large-scale ascent preceding the shortwave trough spreads across diurnally heated higher elevations. Development will be supported further by at least marginally favorable moisture, represented by lower-elevation surface dewpoints now in the upper 40s to low 60s F, and not expected to dry very much via mixing through early/mid afternoon. Still, heating/mixing should be strong enough to build steep low/middle-level lapse rates and "inverted-v" thermodynamic profiles supporting strong/isolated severe gusts, Some of this activity also may take the form of dry thunderstorms, especially in eastern areas -- see SPC Fire Weather products for more on that concern. ..Edwards/Grams.. 08/05/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 AM CDT Mon Aug 05 2024 Valid 051300Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER OHIO VALLEY INTO NEW ENGLAND...ACROSS PORTIONS OF THE UPPER MIDWEST...AND FROM NORTHERN FLORIDA INTO SOUTHERN GEORGIA AND SOUTHEAST SOUTH CAROLINA... ...SUMMARY... Severe thunderstorms are possible today and tonight from the Upper Ohio Valley into New England, across portions of the Upper Midwest, and from northern Florida into southern Georgia and southeast South Carolina. ...Synopsis... With height falls well underway on its northern rim -- over the northern Rockies -- the Four Corners regional anticyclone has become ore zonally elongated, with a shift/reformation of the associated 500-mb high over the San Juan Mountains or adjoining San Luis Valley. Through the period, associated ridging will extend east-southeastward across southern KS to AR, west-southwestward over the LAS area to southern CA, and will rebuild northwestward over the northern Rockies. The latter will occur as a series of closely spaced shortwave perturbations -- apparent in moisture-channel imagery from the western Dakotas to north-central MT -- shift eastward across the Dakotas to MN by 00Z. These features then should cross WI and Lake Michigan tonight. Just west of the ridge, a weak shortwave trough now over the central/northern Sierra should move north-northeastward toward the northern Rockies through the day. Farther east, a strong shortwave trough was evident over northern ON north of Lake Superior, in the southwest quadrant of a vast cyclone covering most of eastern Canada. This trough should move east-southeastward across southernmost QC to ME by 06Z, then over the Canadian Maritimes. At the surface, 11Z analysis showed a wavy, slow-moving (mostly stationary) frontal zone from central New England to a weak low over southern Lake Huron, across southern Lake Michigan and northern IA, to another low over south-central SD between PIR-VTN, then across central WY. As the mid/upper shortwave trough approaches and grazes the area, the eastern part of the front should move slowly southeastward across the Lower Great Lakes, Adirondacks, White Mountains and much of ME by 00Z. The trailing part should drift southward into northern parts of OH/IN/IL, then decelerate/stall overnight. The SD low should ripple east-southeastward along the front and across the Siouxland region by 00Z, then over northern IA tonight. The trailing cold front from there should extend across eastern NE, northwestern KS and southeastern CO by 00Z, stalling overnight over southwestern KS and southeastern CO in response to cyclogenesis near LAA. ...FL/GA/SC -- Hurricane Debby... Hurricane Debby has made landfall in the FL "Big Bend" coastal area, and the center is forecast by NHC to proceed slowly northeastward over the FL/GA line through the period. See SPC Tornado Watch 596 and related mesoscale discussions for near-term potential. Refer to latest NHC advisories for forecast track/intensity of Debby, and tropical watches/warnings. The existing tornado potential southeast of center largely is expected to translate along with Debby, while expanding northeastward to the Atlantic Coast of northeastern FL and GA, as favorable low-level theta-e advection from the Atlantic destabilizes the nearshore airmass there. An extensive area of precip northeast through north of center should be maintained, substantially restricting instability over northwestern FL and southwestern/ south-central GA to the left of the forecast center track, and reinforcing the baroclinic gradient there. That should act as a buoyancy-limiting northwestern bound to the supercell/tornado threat. Meanwhile, as low-level flow veers further on the FL West Coast through the remainder of this morning, and weaker lift with a more skeletal convective structure moves across the area south of center, supercell/tornado potential will diminish there. The optimal CAPE/shear parameter space should shift through northern FL into southeastern GA today, while expanding along the GA and eventually SC Coast later today through tonight. ...Northeast and Great Lakes to upper Mississippi Valley... Through tonight, multiple rounds of strong to severe convection are possible across this lengthy but relatively narrow corridor near the front, through tonight. Damaging winds will be the main concern in the Northeast, though enough low-level shear/hodograph enlargement exists in forecast soundings across parts of northern New England to support some supercell potential. Meanwhile, supercells with large hail and a tornado threat may develop before dark or in early evening between southern MN and southern Lake Michigan. Activity overall should evolve upscale to a more clustered, wind-driven threat with time, lasting later in the evening over western areas. Surface-based development is likely to occur earlier in the eastern "slight risk" area -- from midday through this afternoon, as peripheral mass response to the Canadian perturbation increases low-level convergence and tightens the height gradient aloft. The latter will increase deep shear, though nearly unidirectional wind profiles should persist over the corridor, except in parts of north-central New England and northern IA/southern MN, each to the east of frontal-wave lows. Strong diurnal warming will occur in conjunction with favorable low-level moisture, with surface dewpoints commonly in the mid/upper 60s from OH eastward and low 70s from northern IN across the upper Mississippi Valley. This should yield peak/preconvective MLCAPE ranging from around 500-1500 J/kg over the Northeast -- where midlevel lapse rates will be weaker -- to 2000-3000 J/kg in a narrow corridor near the front from northern OH to the IA/MN border vicinity. However, capping will be stronger over the IA/MN/WI part of the front, and diurnal development/ coverage accessing the greatest surface-based buoyancy is more uncertain than evening/overnight severe hail/gust potential near and north of the front. ...Northern Rockies and vicinity... Isolated to scattered thunderstorms are expected to develop this afternoon and evening over much of ID into western MT, as modest large-scale ascent preceding the shortwave trough spreads across diurnally heated higher elevations. Development will be supported further by at least marginally favorable moisture, represented by lower-elevation surface dewpoints now in the upper 40s to low 60s F, and not expected to dry very much via mixing through early/mid afternoon. Still, heating/mixing should be strong enough to build steep low/middle-level lapse rates and "inverted-v" thermodynamic profiles supporting strong/isolated severe gusts, Some of this activity also may take the form of dry thunderstorms, especially in eastern areas -- see SPC Fire Weather products for more on that concern. ..Edwards/Grams.. 08/05/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 AM CDT Mon Aug 05 2024 Valid 051300Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER OHIO VALLEY INTO NEW ENGLAND...ACROSS PORTIONS OF THE UPPER MIDWEST...AND FROM NORTHERN FLORIDA INTO SOUTHERN GEORGIA AND SOUTHEAST SOUTH CAROLINA... ...SUMMARY... Severe thunderstorms are possible today and tonight from the Upper Ohio Valley into New England, across portions of the Upper Midwest, and from northern Florida into southern Georgia and southeast South Carolina. ...Synopsis... With height falls well underway on its northern rim -- over the northern Rockies -- the Four Corners regional anticyclone has become ore zonally elongated, with a shift/reformation of the associated 500-mb high over the San Juan Mountains or adjoining San Luis Valley. Through the period, associated ridging will extend east-southeastward across southern KS to AR, west-southwestward over the LAS area to southern CA, and will rebuild northwestward over the northern Rockies. The latter will occur as a series of closely spaced shortwave perturbations -- apparent in moisture-channel imagery from the western Dakotas to north-central MT -- shift eastward across the Dakotas to MN by 00Z. These features then should cross WI and Lake Michigan tonight. Just west of the ridge, a weak shortwave trough now over the central/northern Sierra should move north-northeastward toward the northern Rockies through the day. Farther east, a strong shortwave trough was evident over northern ON north of Lake Superior, in the southwest quadrant of a vast cyclone covering most of eastern Canada. This trough should move east-southeastward across southernmost QC to ME by 06Z, then over the Canadian Maritimes. At the surface, 11Z analysis showed a wavy, slow-moving (mostly stationary) frontal zone from central New England to a weak low over southern Lake Huron, across southern Lake Michigan and northern IA, to another low over south-central SD between PIR-VTN, then across central WY. As the mid/upper shortwave trough approaches and grazes the area, the eastern part of the front should move slowly southeastward across the Lower Great Lakes, Adirondacks, White Mountains and much of ME by 00Z. The trailing part should drift southward into northern parts of OH/IN/IL, then decelerate/stall overnight. The SD low should ripple east-southeastward along the front and across the Siouxland region by 00Z, then over northern IA tonight. The trailing cold front from there should extend across eastern NE, northwestern KS and southeastern CO by 00Z, stalling overnight over southwestern KS and southeastern CO in response to cyclogenesis near LAA. ...FL/GA/SC -- Hurricane Debby... Hurricane Debby has made landfall in the FL "Big Bend" coastal area, and the center is forecast by NHC to proceed slowly northeastward over the FL/GA line through the period. See SPC Tornado Watch 596 and related mesoscale discussions for near-term potential. Refer to latest NHC advisories for forecast track/intensity of Debby, and tropical watches/warnings. The existing tornado potential southeast of center largely is expected to translate along with Debby, while expanding northeastward to the Atlantic Coast of northeastern FL and GA, as favorable low-level theta-e advection from the Atlantic destabilizes the nearshore airmass there. An extensive area of precip northeast through north of center should be maintained, substantially restricting instability over northwestern FL and southwestern/ south-central GA to the left of the forecast center track, and reinforcing the baroclinic gradient there. That should act as a buoyancy-limiting northwestern bound to the supercell/tornado threat. Meanwhile, as low-level flow veers further on the FL West Coast through the remainder of this morning, and weaker lift with a more skeletal convective structure moves across the area south of center, supercell/tornado potential will diminish there. The optimal CAPE/shear parameter space should shift through northern FL into southeastern GA today, while expanding along the GA and eventually SC Coast later today through tonight. ...Northeast and Great Lakes to upper Mississippi Valley... Through tonight, multiple rounds of strong to severe convection are possible across this lengthy but relatively narrow corridor near the front, through tonight. Damaging winds will be the main concern in the Northeast, though enough low-level shear/hodograph enlargement exists in forecast soundings across parts of northern New England to support some supercell potential. Meanwhile, supercells with large hail and a tornado threat may develop before dark or in early evening between southern MN and southern Lake Michigan. Activity overall should evolve upscale to a more clustered, wind-driven threat with time, lasting later in the evening over western areas. Surface-based development is likely to occur earlier in the eastern "slight risk" area -- from midday through this afternoon, as peripheral mass response to the Canadian perturbation increases low-level convergence and tightens the height gradient aloft. The latter will increase deep shear, though nearly unidirectional wind profiles should persist over the corridor, except in parts of north-central New England and northern IA/southern MN, each to the east of frontal-wave lows. Strong diurnal warming will occur in conjunction with favorable low-level moisture, with surface dewpoints commonly in the mid/upper 60s from OH eastward and low 70s from northern IN across the upper Mississippi Valley. This should yield peak/preconvective MLCAPE ranging from around 500-1500 J/kg over the Northeast -- where midlevel lapse rates will be weaker -- to 2000-3000 J/kg in a narrow corridor near the front from northern OH to the IA/MN border vicinity. However, capping will be stronger over the IA/MN/WI part of the front, and diurnal development/ coverage accessing the greatest surface-based buoyancy is more uncertain than evening/overnight severe hail/gust potential near and north of the front. ...Northern Rockies and vicinity... Isolated to scattered thunderstorms are expected to develop this afternoon and evening over much of ID into western MT, as modest large-scale ascent preceding the shortwave trough spreads across diurnally heated higher elevations. Development will be supported further by at least marginally favorable moisture, represented by lower-elevation surface dewpoints now in the upper 40s to low 60s F, and not expected to dry very much via mixing through early/mid afternoon. Still, heating/mixing should be strong enough to build steep low/middle-level lapse rates and "inverted-v" thermodynamic profiles supporting strong/isolated severe gusts, Some of this activity also may take the form of dry thunderstorms, especially in eastern areas -- see SPC Fire Weather products for more on that concern. ..Edwards/Grams.. 08/05/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 AM CDT Mon Aug 05 2024 Valid 051300Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER OHIO VALLEY INTO NEW ENGLAND...ACROSS PORTIONS OF THE UPPER MIDWEST...AND FROM NORTHERN FLORIDA INTO SOUTHERN GEORGIA AND SOUTHEAST SOUTH CAROLINA... ...SUMMARY... Severe thunderstorms are possible today and tonight from the Upper Ohio Valley into New England, across portions of the Upper Midwest, and from northern Florida into southern Georgia and southeast South Carolina. ...Synopsis... With height falls well underway on its northern rim -- over the northern Rockies -- the Four Corners regional anticyclone has become ore zonally elongated, with a shift/reformation of the associated 500-mb high over the San Juan Mountains or adjoining San Luis Valley. Through the period, associated ridging will extend east-southeastward across southern KS to AR, west-southwestward over the LAS area to southern CA, and will rebuild northwestward over the northern Rockies. The latter will occur as a series of closely spaced shortwave perturbations -- apparent in moisture-channel imagery from the western Dakotas to north-central MT -- shift eastward across the Dakotas to MN by 00Z. These features then should cross WI and Lake Michigan tonight. Just west of the ridge, a weak shortwave trough now over the central/northern Sierra should move north-northeastward toward the northern Rockies through the day. Farther east, a strong shortwave trough was evident over northern ON north of Lake Superior, in the southwest quadrant of a vast cyclone covering most of eastern Canada. This trough should move east-southeastward across southernmost QC to ME by 06Z, then over the Canadian Maritimes. At the surface, 11Z analysis showed a wavy, slow-moving (mostly stationary) frontal zone from central New England to a weak low over southern Lake Huron, across southern Lake Michigan and northern IA, to another low over south-central SD between PIR-VTN, then across central WY. As the mid/upper shortwave trough approaches and grazes the area, the eastern part of the front should move slowly southeastward across the Lower Great Lakes, Adirondacks, White Mountains and much of ME by 00Z. The trailing part should drift southward into northern parts of OH/IN/IL, then decelerate/stall overnight. The SD low should ripple east-southeastward along the front and across the Siouxland region by 00Z, then over northern IA tonight. The trailing cold front from there should extend across eastern NE, northwestern KS and southeastern CO by 00Z, stalling overnight over southwestern KS and southeastern CO in response to cyclogenesis near LAA. ...FL/GA/SC -- Hurricane Debby... Hurricane Debby has made landfall in the FL "Big Bend" coastal area, and the center is forecast by NHC to proceed slowly northeastward over the FL/GA line through the period. See SPC Tornado Watch 596 and related mesoscale discussions for near-term potential. Refer to latest NHC advisories for forecast track/intensity of Debby, and tropical watches/warnings. The existing tornado potential southeast of center largely is expected to translate along with Debby, while expanding northeastward to the Atlantic Coast of northeastern FL and GA, as favorable low-level theta-e advection from the Atlantic destabilizes the nearshore airmass there. An extensive area of precip northeast through north of center should be maintained, substantially restricting instability over northwestern FL and southwestern/ south-central GA to the left of the forecast center track, and reinforcing the baroclinic gradient there. That should act as a buoyancy-limiting northwestern bound to the supercell/tornado threat. Meanwhile, as low-level flow veers further on the FL West Coast through the remainder of this morning, and weaker lift with a more skeletal convective structure moves across the area south of center, supercell/tornado potential will diminish there. The optimal CAPE/shear parameter space should shift through northern FL into southeastern GA today, while expanding along the GA and eventually SC Coast later today through tonight. ...Northeast and Great Lakes to upper Mississippi Valley... Through tonight, multiple rounds of strong to severe convection are possible across this lengthy but relatively narrow corridor near the front, through tonight. Damaging winds will be the main concern in the Northeast, though enough low-level shear/hodograph enlargement exists in forecast soundings across parts of northern New England to support some supercell potential. Meanwhile, supercells with large hail and a tornado threat may develop before dark or in early evening between southern MN and southern Lake Michigan. Activity overall should evolve upscale to a more clustered, wind-driven threat with time, lasting later in the evening over western areas. Surface-based development is likely to occur earlier in the eastern "slight risk" area -- from midday through this afternoon, as peripheral mass response to the Canadian perturbation increases low-level convergence and tightens the height gradient aloft. The latter will increase deep shear, though nearly unidirectional wind profiles should persist over the corridor, except in parts of north-central New England and northern IA/southern MN, each to the east of frontal-wave lows. Strong diurnal warming will occur in conjunction with favorable low-level moisture, with surface dewpoints commonly in the mid/upper 60s from OH eastward and low 70s from northern IN across the upper Mississippi Valley. This should yield peak/preconvective MLCAPE ranging from around 500-1500 J/kg over the Northeast -- where midlevel lapse rates will be weaker -- to 2000-3000 J/kg in a narrow corridor near the front from northern OH to the IA/MN border vicinity. However, capping will be stronger over the IA/MN/WI part of the front, and diurnal development/ coverage accessing the greatest surface-based buoyancy is more uncertain than evening/overnight severe hail/gust potential near and north of the front. ...Northern Rockies and vicinity... Isolated to scattered thunderstorms are expected to develop this afternoon and evening over much of ID into western MT, as modest large-scale ascent preceding the shortwave trough spreads across diurnally heated higher elevations. Development will be supported further by at least marginally favorable moisture, represented by lower-elevation surface dewpoints now in the upper 40s to low 60s F, and not expected to dry very much via mixing through early/mid afternoon. Still, heating/mixing should be strong enough to build steep low/middle-level lapse rates and "inverted-v" thermodynamic profiles supporting strong/isolated severe gusts, Some of this activity also may take the form of dry thunderstorms, especially in eastern areas -- see SPC Fire Weather products for more on that concern. ..Edwards/Grams.. 08/05/2024 Read more

WW 0596 Status Updates
STATUS REPORT ON WW 596 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1822. ..GRAMS..08/05/24 ATTN...WFO...JAX...TBW...MLB...CHS... STATUS REPORT FOR WT 596 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS FLC001-003-007-017-019-023-031-035-041-049-053-057-069-075-081- 083-089-095-097-101-103-105-107-109-115-117-119-125-127- 051340- FL . FLORIDA COUNTIES INCLUDED ARE ALACHUA BAKER BRADFORD CITRUS CLAY COLUMBIA DUVAL FLAGLER GILCHRIST HARDEE HERNANDO HILLSBOROUGH LAKE LEVY MANATEE MARION NASSAU ORANGE OSCEOLA PASCO PINELLAS POLK PUTNAM ST. JOHNS SARASOTA SEMINOLE SUMTER UNION VOLUSIA GAC025-029-039-049-051-109-127-179-183-191-229-267-299-305- 051340- GA . GEORGIA COUNTIES INCLUDED ARE Read more

WW 0596 Status Updates
STATUS REPORT ON WW 596 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1822. ..GRAMS..08/05/24 ATTN...WFO...JAX...TBW...MLB...CHS... STATUS REPORT FOR WT 596 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS FLC001-003-007-017-019-023-031-035-041-049-053-057-069-075-081- 083-089-095-097-101-103-105-107-109-115-117-119-125-127- 051340- FL . FLORIDA COUNTIES INCLUDED ARE ALACHUA BAKER BRADFORD CITRUS CLAY COLUMBIA DUVAL FLAGLER GILCHRIST HARDEE HERNANDO HILLSBOROUGH LAKE LEVY MANATEE MARION NASSAU ORANGE OSCEOLA PASCO PINELLAS POLK PUTNAM ST. JOHNS SARASOTA SEMINOLE SUMTER UNION VOLUSIA GAC025-029-039-049-051-109-127-179-183-191-229-267-299-305- 051340- GA . GEORGIA COUNTIES INCLUDED ARE Read more

MD 1821 CONCERNING TORNADO WATCH 595... FOR WEST-CENTRAL TO NORTH FL
Mesoscale Discussion 1821 NWS Storm Prediction Center Norman OK 0409 AM CDT Mon Aug 05 2024 Areas affected...west-central to north FL Concerning...Tornado Watch 595... Valid 050909Z - 051045Z The severe weather threat for Tornado Watch 595 continues. SUMMARY...Threat for a couple tornadoes should primarily be confined to the west-central Florida Peninsula through sunrise, but should increase later this morning across parts of central and north Florida. Replacement of WW 595 is expected before its 10Z expiration. DISCUSSION...Transient rotation within outer-band thunderstorms has largely been confined to the west-central FL Peninsula over the past several hours. This near-term threat is roughly centered from Sarasota to western Lake counties, largely south through northeast of Tampa Bay. The 06Z TBW sounding sampled a favorable environment for a couple tornadoes, characterized by MLCAPE near 1000 J/kg amid 0-1 km SRH of 150-200 m2/s2. As limited diabatic surface heating occurs after sunrise beneath the extensive cloud canopy surrounding slow-moving Debby, a gradual boost to MLCAPE should occur farther north and inland. Recent CAM guidance suggests potential for intermediate banded structures to reform north of the Tampa Bay area as this occurs, which would yield a larger spatial extent of the tornado threat. The east-central/ northeast coast of the peninsula will likely have a near-term nil threat owing to meager MLCAPE of about 250 J/kg per the 06Z JAX/XMR soundings, and may struggle to appreciably increase until late morning if an outer band can separately form off the east coast and spread inland. CAM guidance suggests this may tend to focus from the FL/GA border northward later this morning. ..Grams/Edwards.. 08/05/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MLB...TBW...JAX...TAE... LAT...LON 29268304 29848299 30038265 30048230 29688178 29188156 28458142 27888150 27398168 26948211 27088242 27348258 28388281 29268304 Read more

WW 0596 Status Updates
STATUS FOR WATCH 0596 HAS NOT BEEN ISSUED YET Read more

WW 0596 Status Updates
STATUS FOR WATCH 0596 HAS NOT BEEN ISSUED YET Read more

WW 0596 Status Updates
STATUS FOR WATCH 0596 HAS NOT BEEN ISSUED YET Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0353 AM CDT Mon Aug 05 2024 Valid 081200Z - 131200Z ...DISCUSSION... Latest (05/00z) ECENS/GEFS output suggests than an initially prominent mid-level ridge over the Canadian Northwest Territories will gradually become suppressed, with the center of higher heights shifting east-southeastward toward northern Manitoba through early this weekend. Preceding this feature, it appears that a significant positively tilted trough will pivot through northwestern Ontario and the upper Great Lakes, before digging through the lower Great Lakes and upper Ohio Valley vicinity. As this occurs, it appears that Debby's remnant lower/mid-level circulation will finally accelerate northeastward out of the Southeast, and offshore of the Mid Atlantic coast by next weekend. While it might not be out of the question that this could occur in a manner supportive of an appreciable increase in potential for convection capable of producing tornadoes across parts of the Carolinas, Virginia and Delmarva Peninsula vicinity, probabilities for this still seem generally low at this time. Otherwise, modest westerly to northwesterly mid/upper flow developing across the northern Rockies into northern and central U.S. Great Plains, around the periphery of a prominent ridge shifting from the Four Corners into southern Great Plains, may be conditionally supportive of organized convective development through much of the period. However, guidance continues to generally indicate that seasonably modest destabilization will tend to limit the severe weather potential. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0353 AM CDT Mon Aug 05 2024 Valid 081200Z - 131200Z ...DISCUSSION... Latest (05/00z) ECENS/GEFS output suggests than an initially prominent mid-level ridge over the Canadian Northwest Territories will gradually become suppressed, with the center of higher heights shifting east-southeastward toward northern Manitoba through early this weekend. Preceding this feature, it appears that a significant positively tilted trough will pivot through northwestern Ontario and the upper Great Lakes, before digging through the lower Great Lakes and upper Ohio Valley vicinity. As this occurs, it appears that Debby's remnant lower/mid-level circulation will finally accelerate northeastward out of the Southeast, and offshore of the Mid Atlantic coast by next weekend. While it might not be out of the question that this could occur in a manner supportive of an appreciable increase in potential for convection capable of producing tornadoes across parts of the Carolinas, Virginia and Delmarva Peninsula vicinity, probabilities for this still seem generally low at this time. Otherwise, modest westerly to northwesterly mid/upper flow developing across the northern Rockies into northern and central U.S. Great Plains, around the periphery of a prominent ridge shifting from the Four Corners into southern Great Plains, may be conditionally supportive of organized convective development through much of the period. However, guidance continues to generally indicate that seasonably modest destabilization will tend to limit the severe weather potential. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0353 AM CDT Mon Aug 05 2024 Valid 081200Z - 131200Z ...DISCUSSION... Latest (05/00z) ECENS/GEFS output suggests than an initially prominent mid-level ridge over the Canadian Northwest Territories will gradually become suppressed, with the center of higher heights shifting east-southeastward toward northern Manitoba through early this weekend. Preceding this feature, it appears that a significant positively tilted trough will pivot through northwestern Ontario and the upper Great Lakes, before digging through the lower Great Lakes and upper Ohio Valley vicinity. As this occurs, it appears that Debby's remnant lower/mid-level circulation will finally accelerate northeastward out of the Southeast, and offshore of the Mid Atlantic coast by next weekend. While it might not be out of the question that this could occur in a manner supportive of an appreciable increase in potential for convection capable of producing tornadoes across parts of the Carolinas, Virginia and Delmarva Peninsula vicinity, probabilities for this still seem generally low at this time. Otherwise, modest westerly to northwesterly mid/upper flow developing across the northern Rockies into northern and central U.S. Great Plains, around the periphery of a prominent ridge shifting from the Four Corners into southern Great Plains, may be conditionally supportive of organized convective development through much of the period. However, guidance continues to generally indicate that seasonably modest destabilization will tend to limit the severe weather potential. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0353 AM CDT Mon Aug 05 2024 Valid 081200Z - 131200Z ...DISCUSSION... Latest (05/00z) ECENS/GEFS output suggests than an initially prominent mid-level ridge over the Canadian Northwest Territories will gradually become suppressed, with the center of higher heights shifting east-southeastward toward northern Manitoba through early this weekend. Preceding this feature, it appears that a significant positively tilted trough will pivot through northwestern Ontario and the upper Great Lakes, before digging through the lower Great Lakes and upper Ohio Valley vicinity. As this occurs, it appears that Debby's remnant lower/mid-level circulation will finally accelerate northeastward out of the Southeast, and offshore of the Mid Atlantic coast by next weekend. While it might not be out of the question that this could occur in a manner supportive of an appreciable increase in potential for convection capable of producing tornadoes across parts of the Carolinas, Virginia and Delmarva Peninsula vicinity, probabilities for this still seem generally low at this time. Otherwise, modest westerly to northwesterly mid/upper flow developing across the northern Rockies into northern and central U.S. Great Plains, around the periphery of a prominent ridge shifting from the Four Corners into southern Great Plains, may be conditionally supportive of organized convective development through much of the period. However, guidance continues to generally indicate that seasonably modest destabilization will tend to limit the severe weather potential. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0353 AM CDT Mon Aug 05 2024 Valid 081200Z - 131200Z ...DISCUSSION... Latest (05/00z) ECENS/GEFS output suggests than an initially prominent mid-level ridge over the Canadian Northwest Territories will gradually become suppressed, with the center of higher heights shifting east-southeastward toward northern Manitoba through early this weekend. Preceding this feature, it appears that a significant positively tilted trough will pivot through northwestern Ontario and the upper Great Lakes, before digging through the lower Great Lakes and upper Ohio Valley vicinity. As this occurs, it appears that Debby's remnant lower/mid-level circulation will finally accelerate northeastward out of the Southeast, and offshore of the Mid Atlantic coast by next weekend. While it might not be out of the question that this could occur in a manner supportive of an appreciable increase in potential for convection capable of producing tornadoes across parts of the Carolinas, Virginia and Delmarva Peninsula vicinity, probabilities for this still seem generally low at this time. Otherwise, modest westerly to northwesterly mid/upper flow developing across the northern Rockies into northern and central U.S. Great Plains, around the periphery of a prominent ridge shifting from the Four Corners into southern Great Plains, may be conditionally supportive of organized convective development through much of the period. However, guidance continues to generally indicate that seasonably modest destabilization will tend to limit the severe weather potential. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0353 AM CDT Mon Aug 05 2024 Valid 081200Z - 131200Z ...DISCUSSION... Latest (05/00z) ECENS/GEFS output suggests than an initially prominent mid-level ridge over the Canadian Northwest Territories will gradually become suppressed, with the center of higher heights shifting east-southeastward toward northern Manitoba through early this weekend. Preceding this feature, it appears that a significant positively tilted trough will pivot through northwestern Ontario and the upper Great Lakes, before digging through the lower Great Lakes and upper Ohio Valley vicinity. As this occurs, it appears that Debby's remnant lower/mid-level circulation will finally accelerate northeastward out of the Southeast, and offshore of the Mid Atlantic coast by next weekend. While it might not be out of the question that this could occur in a manner supportive of an appreciable increase in potential for convection capable of producing tornadoes across parts of the Carolinas, Virginia and Delmarva Peninsula vicinity, probabilities for this still seem generally low at this time. Otherwise, modest westerly to northwesterly mid/upper flow developing across the northern Rockies into northern and central U.S. Great Plains, around the periphery of a prominent ridge shifting from the Four Corners into southern Great Plains, may be conditionally supportive of organized convective development through much of the period. However, guidance continues to generally indicate that seasonably modest destabilization will tend to limit the severe weather potential. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0353 AM CDT Mon Aug 05 2024 Valid 081200Z - 131200Z ...DISCUSSION... Latest (05/00z) ECENS/GEFS output suggests than an initially prominent mid-level ridge over the Canadian Northwest Territories will gradually become suppressed, with the center of higher heights shifting east-southeastward toward northern Manitoba through early this weekend. Preceding this feature, it appears that a significant positively tilted trough will pivot through northwestern Ontario and the upper Great Lakes, before digging through the lower Great Lakes and upper Ohio Valley vicinity. As this occurs, it appears that Debby's remnant lower/mid-level circulation will finally accelerate northeastward out of the Southeast, and offshore of the Mid Atlantic coast by next weekend. While it might not be out of the question that this could occur in a manner supportive of an appreciable increase in potential for convection capable of producing tornadoes across parts of the Carolinas, Virginia and Delmarva Peninsula vicinity, probabilities for this still seem generally low at this time. Otherwise, modest westerly to northwesterly mid/upper flow developing across the northern Rockies into northern and central U.S. Great Plains, around the periphery of a prominent ridge shifting from the Four Corners into southern Great Plains, may be conditionally supportive of organized convective development through much of the period. However, guidance continues to generally indicate that seasonably modest destabilization will tend to limit the severe weather potential. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0353 AM CDT Mon Aug 05 2024 Valid 081200Z - 131200Z ...DISCUSSION... Latest (05/00z) ECENS/GEFS output suggests than an initially prominent mid-level ridge over the Canadian Northwest Territories will gradually become suppressed, with the center of higher heights shifting east-southeastward toward northern Manitoba through early this weekend. Preceding this feature, it appears that a significant positively tilted trough will pivot through northwestern Ontario and the upper Great Lakes, before digging through the lower Great Lakes and upper Ohio Valley vicinity. As this occurs, it appears that Debby's remnant lower/mid-level circulation will finally accelerate northeastward out of the Southeast, and offshore of the Mid Atlantic coast by next weekend. While it might not be out of the question that this could occur in a manner supportive of an appreciable increase in potential for convection capable of producing tornadoes across parts of the Carolinas, Virginia and Delmarva Peninsula vicinity, probabilities for this still seem generally low at this time. Otherwise, modest westerly to northwesterly mid/upper flow developing across the northern Rockies into northern and central U.S. Great Plains, around the periphery of a prominent ridge shifting from the Four Corners into southern Great Plains, may be conditionally supportive of organized convective development through much of the period. However, guidance continues to generally indicate that seasonably modest destabilization will tend to limit the severe weather potential. Read more