Aggregator

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1019 AM CST Tue Nov 05 2024 Valid 051630Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF LOUISIANA.... ...SUMMARY... Locally damaging winds and perhaps a tornado or two may occur across a portion of the Lower and Mid Mississippi Valleys, and central to southern Wisconsin. ...LA/MS... A large upper trough is present today over the central US, with the primary surface boundary extending from eastern AR southward into central LA. Scattered thunderstorms have been occurring along and ahead of this boundary, including several storms exhibiting low and mid level rotation. Winds aloft are expected to weaken through the day, but there is a continued chance of isolated tornadoes for a few hours late this morning and early afternoon. Therefore have added a small SLGT risk area. Please refer to MCD #2213 for further details on this environment. ...AR/TN/KY/IN... A narrow line of thunderstorms is noted along the boundary across eastern AR. Several morning CAM solutions suggest this line may maintain some character through the afternoon and it tracks northeastward across parts of the mid MS Valley. Visible satellite imagery shows breaks in the clouds across this region, providing some heating and destabilization. Also, low level wind fields will remain rather strong ahead of the convection. This may be sufficient for locally gusty/damaging wind gusts this afternoon. ....WI... A few low-topped showers and thunderstorms will likely form later this afternoon near a deepening surface low over WI. Widespread clouds will limit destabilization, but there is some potential for locally gusty/damaging winds during the peak-heating period. ..Hart/Supinie.. 11/05/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1019 AM CST Tue Nov 05 2024 Valid 051630Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF LOUISIANA.... ...SUMMARY... Locally damaging winds and perhaps a tornado or two may occur across a portion of the Lower and Mid Mississippi Valleys, and central to southern Wisconsin. ...LA/MS... A large upper trough is present today over the central US, with the primary surface boundary extending from eastern AR southward into central LA. Scattered thunderstorms have been occurring along and ahead of this boundary, including several storms exhibiting low and mid level rotation. Winds aloft are expected to weaken through the day, but there is a continued chance of isolated tornadoes for a few hours late this morning and early afternoon. Therefore have added a small SLGT risk area. Please refer to MCD #2213 for further details on this environment. ...AR/TN/KY/IN... A narrow line of thunderstorms is noted along the boundary across eastern AR. Several morning CAM solutions suggest this line may maintain some character through the afternoon and it tracks northeastward across parts of the mid MS Valley. Visible satellite imagery shows breaks in the clouds across this region, providing some heating and destabilization. Also, low level wind fields will remain rather strong ahead of the convection. This may be sufficient for locally gusty/damaging wind gusts this afternoon. ....WI... A few low-topped showers and thunderstorms will likely form later this afternoon near a deepening surface low over WI. Widespread clouds will limit destabilization, but there is some potential for locally gusty/damaging winds during the peak-heating period. ..Hart/Supinie.. 11/05/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1019 AM CST Tue Nov 05 2024 Valid 051630Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF LOUISIANA.... ...SUMMARY... Locally damaging winds and perhaps a tornado or two may occur across a portion of the Lower and Mid Mississippi Valleys, and central to southern Wisconsin. ...LA/MS... A large upper trough is present today over the central US, with the primary surface boundary extending from eastern AR southward into central LA. Scattered thunderstorms have been occurring along and ahead of this boundary, including several storms exhibiting low and mid level rotation. Winds aloft are expected to weaken through the day, but there is a continued chance of isolated tornadoes for a few hours late this morning and early afternoon. Therefore have added a small SLGT risk area. Please refer to MCD #2213 for further details on this environment. ...AR/TN/KY/IN... A narrow line of thunderstorms is noted along the boundary across eastern AR. Several morning CAM solutions suggest this line may maintain some character through the afternoon and it tracks northeastward across parts of the mid MS Valley. Visible satellite imagery shows breaks in the clouds across this region, providing some heating and destabilization. Also, low level wind fields will remain rather strong ahead of the convection. This may be sufficient for locally gusty/damaging wind gusts this afternoon. ....WI... A few low-topped showers and thunderstorms will likely form later this afternoon near a deepening surface low over WI. Widespread clouds will limit destabilization, but there is some potential for locally gusty/damaging winds during the peak-heating period. ..Hart/Supinie.. 11/05/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1019 AM CST Tue Nov 05 2024 Valid 051630Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF LOUISIANA.... ...SUMMARY... Locally damaging winds and perhaps a tornado or two may occur across a portion of the Lower and Mid Mississippi Valleys, and central to southern Wisconsin. ...LA/MS... A large upper trough is present today over the central US, with the primary surface boundary extending from eastern AR southward into central LA. Scattered thunderstorms have been occurring along and ahead of this boundary, including several storms exhibiting low and mid level rotation. Winds aloft are expected to weaken through the day, but there is a continued chance of isolated tornadoes for a few hours late this morning and early afternoon. Therefore have added a small SLGT risk area. Please refer to MCD #2213 for further details on this environment. ...AR/TN/KY/IN... A narrow line of thunderstorms is noted along the boundary across eastern AR. Several morning CAM solutions suggest this line may maintain some character through the afternoon and it tracks northeastward across parts of the mid MS Valley. Visible satellite imagery shows breaks in the clouds across this region, providing some heating and destabilization. Also, low level wind fields will remain rather strong ahead of the convection. This may be sufficient for locally gusty/damaging wind gusts this afternoon. ....WI... A few low-topped showers and thunderstorms will likely form later this afternoon near a deepening surface low over WI. Widespread clouds will limit destabilization, but there is some potential for locally gusty/damaging winds during the peak-heating period. ..Hart/Supinie.. 11/05/2024 Read more

MD 2213 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR MUCH OF LOUISIANA AND INTO SOUTHWESTERN MISSISSIPPI
Mesoscale Discussion 2213 NWS Storm Prediction Center Norman OK 1006 AM CST Tue Nov 05 2024 Areas affected...much of Louisiana and into southwestern Mississippi Concerning...Severe potential...Watch possible Valid 051606Z - 051700Z Probability of Watch Issuance...40 percent SUMMARY...Occasionally rotating storms are expected over the next few hours across parts of Louisiana and adjacent southwestern Mississippi, ahead of the advancing cold front. Current indications are that WW issuance will remain unnecessary. DISCUSSION...Latest observational data shows a cold front advancing across western Louisiana and far southeastern Texas at this time, with a band of generally weak convection along and behind the boundary. Meanwhile, with a very moist warm-sector boundary layer contributing to 500 to 1000 J/kg mixed-layer CAPE per RAP-based objective analysis, widely scattered pre-frontal storms have evolved, with a couple of the longer-lived updrafts exhibiting low-level rotation. Thus far, intensity of the updrafts and strength of rotation has remained somewhat limited generally -- suggesting only weak/brief tornado potential; a recent tornado has been reported but with a storm that is exhibiting only limited low-level rotation suggestive of limited tornado intensity. Given observed winds veering gradually with height but only moderate in magnitude, the current/limited degree of updraft rotation should be maintained. With that said, we will continue to monitor convective evolution over the next couple of hours, as an increase in coverage of the stronger updrafts could require closer examination of potential for WW issuance. ..Goss/Hart.. 11/05/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...JAN...LIX...LCH...SHV... LAT...LON 29829370 31299302 32729238 32969185 31619093 30109069 29189116 29829370 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0650 AM CST Tue Nov 05 2024 Valid 051300Z - 061200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS A PORTION OF THE SABINE TO LOWER MISSISSIPPI VALLEYS...AND CENTRAL TO SOUTHERN WISCONSIN... ...SUMMARY... A brief tornado or two and locally damaging winds may occur across a portion of the Sabine to Lower Mississippi Valleys, and central to southern Wisconsin. ...Synopsis... Mid/upper-level longwave troughing has become well-established over the western CONUS. That will persist through this and more outlook periods, as a series of synoptic to large shortwave troughs traverses the associated cyclonic-flow field. The leading such perturbation -- now located from the central Plains south- southwestward over the southern High Plains to far west TX -- will eject northeastward and weaken. By 00Z, the residual, strongly positively tilted trough should extend from a vorticity max over western WI, across central/southwestern MO to central TX. The perturbation will deamplify greatly overnight and accelerate to a position near the western QC/ON border, Lake Huron and IN by 12Z. Meanwhile, an upstream shortwave trough -- evident in moisture- channel imagery over ID -- will dig southeastward and strengthen greatly through the period. By 12Z, it should be oriented northeast/southwest through a developing 500-mb low over the Four Corners. The 11Z surface analysis showed an elongated area of low pressure from southern WI to northwestern MO, with cold front through central OK and north-central/central TX. The front was preceded by an extensive convective band and associated outflow boundary from central IL to central AR, east TX, and deep south TX. By 00Z, the front should catch up (or nearly so) to what remains of the convective boundary, with the combined baroclinic zone extending from a consolidated low over northern WI across the Mid-South region to the northwestern Gulf shelf waters off TX. By 12Z, the front should extend from Lower MI across western portions of KY/TN/MS to southwestern LA and the northwestern Gulf. ...Sabine to Lower Mississippi Valleys... The ongoing convective band, near the western edge of the "Marginal Risk" area, should weaken overall through mid-morning. However, an isolated damaging gust or brief tornado cannot be ruled out in the meantime with any associated or preceding cell that may take advantage of lingering favorable deep shear and high theta-e, in a northward-narrowing corridor. After a relative lull of a few hours, widely scattered to scattered thunderstorms are forecast along the boundary this afternoon into early evening, with isolated damaging gusts and/or a tornado possible. Afternoon boundary-layer destabilization is anticipated ahead of the convective boundary, from both fragmented/cloud- modulated surface heating and low-level theta-e advection. A corridor of surface dewpoints in the upper 60s to low 70s F will persist an expand slightly northward ahead of the boundary. With no antecedent EML and minimal MLCINH, this should offset modest midlevel lapse rates enough to result in effectively uninhibited buoyancy, supporting an increase in convective coverage and local intensity this afternoon. Peak MLCAPE should range from around 500-800 J/kg over a narrow corridor of the Mid-South, widening/increasing to around 1000-1500 J/kg over southern LA. By contrast, lift along the boundary, and in the form of deep-layer ascent preceding the weakening mid/upper trough, will be greater over the Mid-South, until some nebulous point where too little instability exists to support organized convection. The outlook has been elongated northward somewhat to cover the marginal-buoyancy plume near the Mississippi River. ...WI... Isolated to widely scattered, shallow thunderstorms are possible this afternoon, in an arc near the front and the organizing surface low. A few cells may produce damaging gusts. A brief tornado also may occur, especially with any cells that can linger within a narrow zone of overlap between favorably, isallobarically backed near- surface winds and weak boundary-layer instability. A low-confidence and quite conditional scenario exists here, with abundant antecedent clouds and precip likely to limit destabilization for most of the day. Forecast soundings suggest enough large-scale ascent aloft to cool midlevels a degree or two C, though lapse rates still will be meager. Areas that can experience a couple hours of relatively unimpeded heating may attain 250-500 J/kg MLCAPE. ..Edwards/Mosier.. 11/05/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0650 AM CST Tue Nov 05 2024 Valid 051300Z - 061200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS A PORTION OF THE SABINE TO LOWER MISSISSIPPI VALLEYS...AND CENTRAL TO SOUTHERN WISCONSIN... ...SUMMARY... A brief tornado or two and locally damaging winds may occur across a portion of the Sabine to Lower Mississippi Valleys, and central to southern Wisconsin. ...Synopsis... Mid/upper-level longwave troughing has become well-established over the western CONUS. That will persist through this and more outlook periods, as a series of synoptic to large shortwave troughs traverses the associated cyclonic-flow field. The leading such perturbation -- now located from the central Plains south- southwestward over the southern High Plains to far west TX -- will eject northeastward and weaken. By 00Z, the residual, strongly positively tilted trough should extend from a vorticity max over western WI, across central/southwestern MO to central TX. The perturbation will deamplify greatly overnight and accelerate to a position near the western QC/ON border, Lake Huron and IN by 12Z. Meanwhile, an upstream shortwave trough -- evident in moisture- channel imagery over ID -- will dig southeastward and strengthen greatly through the period. By 12Z, it should be oriented northeast/southwest through a developing 500-mb low over the Four Corners. The 11Z surface analysis showed an elongated area of low pressure from southern WI to northwestern MO, with cold front through central OK and north-central/central TX. The front was preceded by an extensive convective band and associated outflow boundary from central IL to central AR, east TX, and deep south TX. By 00Z, the front should catch up (or nearly so) to what remains of the convective boundary, with the combined baroclinic zone extending from a consolidated low over northern WI across the Mid-South region to the northwestern Gulf shelf waters off TX. By 12Z, the front should extend from Lower MI across western portions of KY/TN/MS to southwestern LA and the northwestern Gulf. ...Sabine to Lower Mississippi Valleys... The ongoing convective band, near the western edge of the "Marginal Risk" area, should weaken overall through mid-morning. However, an isolated damaging gust or brief tornado cannot be ruled out in the meantime with any associated or preceding cell that may take advantage of lingering favorable deep shear and high theta-e, in a northward-narrowing corridor. After a relative lull of a few hours, widely scattered to scattered thunderstorms are forecast along the boundary this afternoon into early evening, with isolated damaging gusts and/or a tornado possible. Afternoon boundary-layer destabilization is anticipated ahead of the convective boundary, from both fragmented/cloud- modulated surface heating and low-level theta-e advection. A corridor of surface dewpoints in the upper 60s to low 70s F will persist an expand slightly northward ahead of the boundary. With no antecedent EML and minimal MLCINH, this should offset modest midlevel lapse rates enough to result in effectively uninhibited buoyancy, supporting an increase in convective coverage and local intensity this afternoon. Peak MLCAPE should range from around 500-800 J/kg over a narrow corridor of the Mid-South, widening/increasing to around 1000-1500 J/kg over southern LA. By contrast, lift along the boundary, and in the form of deep-layer ascent preceding the weakening mid/upper trough, will be greater over the Mid-South, until some nebulous point where too little instability exists to support organized convection. The outlook has been elongated northward somewhat to cover the marginal-buoyancy plume near the Mississippi River. ...WI... Isolated to widely scattered, shallow thunderstorms are possible this afternoon, in an arc near the front and the organizing surface low. A few cells may produce damaging gusts. A brief tornado also may occur, especially with any cells that can linger within a narrow zone of overlap between favorably, isallobarically backed near- surface winds and weak boundary-layer instability. A low-confidence and quite conditional scenario exists here, with abundant antecedent clouds and precip likely to limit destabilization for most of the day. Forecast soundings suggest enough large-scale ascent aloft to cool midlevels a degree or two C, though lapse rates still will be meager. Areas that can experience a couple hours of relatively unimpeded heating may attain 250-500 J/kg MLCAPE. ..Edwards/Mosier.. 11/05/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0650 AM CST Tue Nov 05 2024 Valid 051300Z - 061200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS A PORTION OF THE SABINE TO LOWER MISSISSIPPI VALLEYS...AND CENTRAL TO SOUTHERN WISCONSIN... ...SUMMARY... A brief tornado or two and locally damaging winds may occur across a portion of the Sabine to Lower Mississippi Valleys, and central to southern Wisconsin. ...Synopsis... Mid/upper-level longwave troughing has become well-established over the western CONUS. That will persist through this and more outlook periods, as a series of synoptic to large shortwave troughs traverses the associated cyclonic-flow field. The leading such perturbation -- now located from the central Plains south- southwestward over the southern High Plains to far west TX -- will eject northeastward and weaken. By 00Z, the residual, strongly positively tilted trough should extend from a vorticity max over western WI, across central/southwestern MO to central TX. The perturbation will deamplify greatly overnight and accelerate to a position near the western QC/ON border, Lake Huron and IN by 12Z. Meanwhile, an upstream shortwave trough -- evident in moisture- channel imagery over ID -- will dig southeastward and strengthen greatly through the period. By 12Z, it should be oriented northeast/southwest through a developing 500-mb low over the Four Corners. The 11Z surface analysis showed an elongated area of low pressure from southern WI to northwestern MO, with cold front through central OK and north-central/central TX. The front was preceded by an extensive convective band and associated outflow boundary from central IL to central AR, east TX, and deep south TX. By 00Z, the front should catch up (or nearly so) to what remains of the convective boundary, with the combined baroclinic zone extending from a consolidated low over northern WI across the Mid-South region to the northwestern Gulf shelf waters off TX. By 12Z, the front should extend from Lower MI across western portions of KY/TN/MS to southwestern LA and the northwestern Gulf. ...Sabine to Lower Mississippi Valleys... The ongoing convective band, near the western edge of the "Marginal Risk" area, should weaken overall through mid-morning. However, an isolated damaging gust or brief tornado cannot be ruled out in the meantime with any associated or preceding cell that may take advantage of lingering favorable deep shear and high theta-e, in a northward-narrowing corridor. After a relative lull of a few hours, widely scattered to scattered thunderstorms are forecast along the boundary this afternoon into early evening, with isolated damaging gusts and/or a tornado possible. Afternoon boundary-layer destabilization is anticipated ahead of the convective boundary, from both fragmented/cloud- modulated surface heating and low-level theta-e advection. A corridor of surface dewpoints in the upper 60s to low 70s F will persist an expand slightly northward ahead of the boundary. With no antecedent EML and minimal MLCINH, this should offset modest midlevel lapse rates enough to result in effectively uninhibited buoyancy, supporting an increase in convective coverage and local intensity this afternoon. Peak MLCAPE should range from around 500-800 J/kg over a narrow corridor of the Mid-South, widening/increasing to around 1000-1500 J/kg over southern LA. By contrast, lift along the boundary, and in the form of deep-layer ascent preceding the weakening mid/upper trough, will be greater over the Mid-South, until some nebulous point where too little instability exists to support organized convection. The outlook has been elongated northward somewhat to cover the marginal-buoyancy plume near the Mississippi River. ...WI... Isolated to widely scattered, shallow thunderstorms are possible this afternoon, in an arc near the front and the organizing surface low. A few cells may produce damaging gusts. A brief tornado also may occur, especially with any cells that can linger within a narrow zone of overlap between favorably, isallobarically backed near- surface winds and weak boundary-layer instability. A low-confidence and quite conditional scenario exists here, with abundant antecedent clouds and precip likely to limit destabilization for most of the day. Forecast soundings suggest enough large-scale ascent aloft to cool midlevels a degree or two C, though lapse rates still will be meager. Areas that can experience a couple hours of relatively unimpeded heating may attain 250-500 J/kg MLCAPE. ..Edwards/Mosier.. 11/05/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0650 AM CST Tue Nov 05 2024 Valid 051300Z - 061200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS A PORTION OF THE SABINE TO LOWER MISSISSIPPI VALLEYS...AND CENTRAL TO SOUTHERN WISCONSIN... ...SUMMARY... A brief tornado or two and locally damaging winds may occur across a portion of the Sabine to Lower Mississippi Valleys, and central to southern Wisconsin. ...Synopsis... Mid/upper-level longwave troughing has become well-established over the western CONUS. That will persist through this and more outlook periods, as a series of synoptic to large shortwave troughs traverses the associated cyclonic-flow field. The leading such perturbation -- now located from the central Plains south- southwestward over the southern High Plains to far west TX -- will eject northeastward and weaken. By 00Z, the residual, strongly positively tilted trough should extend from a vorticity max over western WI, across central/southwestern MO to central TX. The perturbation will deamplify greatly overnight and accelerate to a position near the western QC/ON border, Lake Huron and IN by 12Z. Meanwhile, an upstream shortwave trough -- evident in moisture- channel imagery over ID -- will dig southeastward and strengthen greatly through the period. By 12Z, it should be oriented northeast/southwest through a developing 500-mb low over the Four Corners. The 11Z surface analysis showed an elongated area of low pressure from southern WI to northwestern MO, with cold front through central OK and north-central/central TX. The front was preceded by an extensive convective band and associated outflow boundary from central IL to central AR, east TX, and deep south TX. By 00Z, the front should catch up (or nearly so) to what remains of the convective boundary, with the combined baroclinic zone extending from a consolidated low over northern WI across the Mid-South region to the northwestern Gulf shelf waters off TX. By 12Z, the front should extend from Lower MI across western portions of KY/TN/MS to southwestern LA and the northwestern Gulf. ...Sabine to Lower Mississippi Valleys... The ongoing convective band, near the western edge of the "Marginal Risk" area, should weaken overall through mid-morning. However, an isolated damaging gust or brief tornado cannot be ruled out in the meantime with any associated or preceding cell that may take advantage of lingering favorable deep shear and high theta-e, in a northward-narrowing corridor. After a relative lull of a few hours, widely scattered to scattered thunderstorms are forecast along the boundary this afternoon into early evening, with isolated damaging gusts and/or a tornado possible. Afternoon boundary-layer destabilization is anticipated ahead of the convective boundary, from both fragmented/cloud- modulated surface heating and low-level theta-e advection. A corridor of surface dewpoints in the upper 60s to low 70s F will persist an expand slightly northward ahead of the boundary. With no antecedent EML and minimal MLCINH, this should offset modest midlevel lapse rates enough to result in effectively uninhibited buoyancy, supporting an increase in convective coverage and local intensity this afternoon. Peak MLCAPE should range from around 500-800 J/kg over a narrow corridor of the Mid-South, widening/increasing to around 1000-1500 J/kg over southern LA. By contrast, lift along the boundary, and in the form of deep-layer ascent preceding the weakening mid/upper trough, will be greater over the Mid-South, until some nebulous point where too little instability exists to support organized convection. The outlook has been elongated northward somewhat to cover the marginal-buoyancy plume near the Mississippi River. ...WI... Isolated to widely scattered, shallow thunderstorms are possible this afternoon, in an arc near the front and the organizing surface low. A few cells may produce damaging gusts. A brief tornado also may occur, especially with any cells that can linger within a narrow zone of overlap between favorably, isallobarically backed near- surface winds and weak boundary-layer instability. A low-confidence and quite conditional scenario exists here, with abundant antecedent clouds and precip likely to limit destabilization for most of the day. Forecast soundings suggest enough large-scale ascent aloft to cool midlevels a degree or two C, though lapse rates still will be meager. Areas that can experience a couple hours of relatively unimpeded heating may attain 250-500 J/kg MLCAPE. ..Edwards/Mosier.. 11/05/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0650 AM CST Tue Nov 05 2024 Valid 051300Z - 061200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS A PORTION OF THE SABINE TO LOWER MISSISSIPPI VALLEYS...AND CENTRAL TO SOUTHERN WISCONSIN... ...SUMMARY... A brief tornado or two and locally damaging winds may occur across a portion of the Sabine to Lower Mississippi Valleys, and central to southern Wisconsin. ...Synopsis... Mid/upper-level longwave troughing has become well-established over the western CONUS. That will persist through this and more outlook periods, as a series of synoptic to large shortwave troughs traverses the associated cyclonic-flow field. The leading such perturbation -- now located from the central Plains south- southwestward over the southern High Plains to far west TX -- will eject northeastward and weaken. By 00Z, the residual, strongly positively tilted trough should extend from a vorticity max over western WI, across central/southwestern MO to central TX. The perturbation will deamplify greatly overnight and accelerate to a position near the western QC/ON border, Lake Huron and IN by 12Z. Meanwhile, an upstream shortwave trough -- evident in moisture- channel imagery over ID -- will dig southeastward and strengthen greatly through the period. By 12Z, it should be oriented northeast/southwest through a developing 500-mb low over the Four Corners. The 11Z surface analysis showed an elongated area of low pressure from southern WI to northwestern MO, with cold front through central OK and north-central/central TX. The front was preceded by an extensive convective band and associated outflow boundary from central IL to central AR, east TX, and deep south TX. By 00Z, the front should catch up (or nearly so) to what remains of the convective boundary, with the combined baroclinic zone extending from a consolidated low over northern WI across the Mid-South region to the northwestern Gulf shelf waters off TX. By 12Z, the front should extend from Lower MI across western portions of KY/TN/MS to southwestern LA and the northwestern Gulf. ...Sabine to Lower Mississippi Valleys... The ongoing convective band, near the western edge of the "Marginal Risk" area, should weaken overall through mid-morning. However, an isolated damaging gust or brief tornado cannot be ruled out in the meantime with any associated or preceding cell that may take advantage of lingering favorable deep shear and high theta-e, in a northward-narrowing corridor. After a relative lull of a few hours, widely scattered to scattered thunderstorms are forecast along the boundary this afternoon into early evening, with isolated damaging gusts and/or a tornado possible. Afternoon boundary-layer destabilization is anticipated ahead of the convective boundary, from both fragmented/cloud- modulated surface heating and low-level theta-e advection. A corridor of surface dewpoints in the upper 60s to low 70s F will persist an expand slightly northward ahead of the boundary. With no antecedent EML and minimal MLCINH, this should offset modest midlevel lapse rates enough to result in effectively uninhibited buoyancy, supporting an increase in convective coverage and local intensity this afternoon. Peak MLCAPE should range from around 500-800 J/kg over a narrow corridor of the Mid-South, widening/increasing to around 1000-1500 J/kg over southern LA. By contrast, lift along the boundary, and in the form of deep-layer ascent preceding the weakening mid/upper trough, will be greater over the Mid-South, until some nebulous point where too little instability exists to support organized convection. The outlook has been elongated northward somewhat to cover the marginal-buoyancy plume near the Mississippi River. ...WI... Isolated to widely scattered, shallow thunderstorms are possible this afternoon, in an arc near the front and the organizing surface low. A few cells may produce damaging gusts. A brief tornado also may occur, especially with any cells that can linger within a narrow zone of overlap between favorably, isallobarically backed near- surface winds and weak boundary-layer instability. A low-confidence and quite conditional scenario exists here, with abundant antecedent clouds and precip likely to limit destabilization for most of the day. Forecast soundings suggest enough large-scale ascent aloft to cool midlevels a degree or two C, though lapse rates still will be meager. Areas that can experience a couple hours of relatively unimpeded heating may attain 250-500 J/kg MLCAPE. ..Edwards/Mosier.. 11/05/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0650 AM CST Tue Nov 05 2024 Valid 051300Z - 061200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS A PORTION OF THE SABINE TO LOWER MISSISSIPPI VALLEYS...AND CENTRAL TO SOUTHERN WISCONSIN... ...SUMMARY... A brief tornado or two and locally damaging winds may occur across a portion of the Sabine to Lower Mississippi Valleys, and central to southern Wisconsin. ...Synopsis... Mid/upper-level longwave troughing has become well-established over the western CONUS. That will persist through this and more outlook periods, as a series of synoptic to large shortwave troughs traverses the associated cyclonic-flow field. The leading such perturbation -- now located from the central Plains south- southwestward over the southern High Plains to far west TX -- will eject northeastward and weaken. By 00Z, the residual, strongly positively tilted trough should extend from a vorticity max over western WI, across central/southwestern MO to central TX. The perturbation will deamplify greatly overnight and accelerate to a position near the western QC/ON border, Lake Huron and IN by 12Z. Meanwhile, an upstream shortwave trough -- evident in moisture- channel imagery over ID -- will dig southeastward and strengthen greatly through the period. By 12Z, it should be oriented northeast/southwest through a developing 500-mb low over the Four Corners. The 11Z surface analysis showed an elongated area of low pressure from southern WI to northwestern MO, with cold front through central OK and north-central/central TX. The front was preceded by an extensive convective band and associated outflow boundary from central IL to central AR, east TX, and deep south TX. By 00Z, the front should catch up (or nearly so) to what remains of the convective boundary, with the combined baroclinic zone extending from a consolidated low over northern WI across the Mid-South region to the northwestern Gulf shelf waters off TX. By 12Z, the front should extend from Lower MI across western portions of KY/TN/MS to southwestern LA and the northwestern Gulf. ...Sabine to Lower Mississippi Valleys... The ongoing convective band, near the western edge of the "Marginal Risk" area, should weaken overall through mid-morning. However, an isolated damaging gust or brief tornado cannot be ruled out in the meantime with any associated or preceding cell that may take advantage of lingering favorable deep shear and high theta-e, in a northward-narrowing corridor. After a relative lull of a few hours, widely scattered to scattered thunderstorms are forecast along the boundary this afternoon into early evening, with isolated damaging gusts and/or a tornado possible. Afternoon boundary-layer destabilization is anticipated ahead of the convective boundary, from both fragmented/cloud- modulated surface heating and low-level theta-e advection. A corridor of surface dewpoints in the upper 60s to low 70s F will persist an expand slightly northward ahead of the boundary. With no antecedent EML and minimal MLCINH, this should offset modest midlevel lapse rates enough to result in effectively uninhibited buoyancy, supporting an increase in convective coverage and local intensity this afternoon. Peak MLCAPE should range from around 500-800 J/kg over a narrow corridor of the Mid-South, widening/increasing to around 1000-1500 J/kg over southern LA. By contrast, lift along the boundary, and in the form of deep-layer ascent preceding the weakening mid/upper trough, will be greater over the Mid-South, until some nebulous point where too little instability exists to support organized convection. The outlook has been elongated northward somewhat to cover the marginal-buoyancy plume near the Mississippi River. ...WI... Isolated to widely scattered, shallow thunderstorms are possible this afternoon, in an arc near the front and the organizing surface low. A few cells may produce damaging gusts. A brief tornado also may occur, especially with any cells that can linger within a narrow zone of overlap between favorably, isallobarically backed near- surface winds and weak boundary-layer instability. A low-confidence and quite conditional scenario exists here, with abundant antecedent clouds and precip likely to limit destabilization for most of the day. Forecast soundings suggest enough large-scale ascent aloft to cool midlevels a degree or two C, though lapse rates still will be meager. Areas that can experience a couple hours of relatively unimpeded heating may attain 250-500 J/kg MLCAPE. ..Edwards/Mosier.. 11/05/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0650 AM CST Tue Nov 05 2024 Valid 051300Z - 061200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS A PORTION OF THE SABINE TO LOWER MISSISSIPPI VALLEYS...AND CENTRAL TO SOUTHERN WISCONSIN... ...SUMMARY... A brief tornado or two and locally damaging winds may occur across a portion of the Sabine to Lower Mississippi Valleys, and central to southern Wisconsin. ...Synopsis... Mid/upper-level longwave troughing has become well-established over the western CONUS. That will persist through this and more outlook periods, as a series of synoptic to large shortwave troughs traverses the associated cyclonic-flow field. The leading such perturbation -- now located from the central Plains south- southwestward over the southern High Plains to far west TX -- will eject northeastward and weaken. By 00Z, the residual, strongly positively tilted trough should extend from a vorticity max over western WI, across central/southwestern MO to central TX. The perturbation will deamplify greatly overnight and accelerate to a position near the western QC/ON border, Lake Huron and IN by 12Z. Meanwhile, an upstream shortwave trough -- evident in moisture- channel imagery over ID -- will dig southeastward and strengthen greatly through the period. By 12Z, it should be oriented northeast/southwest through a developing 500-mb low over the Four Corners. The 11Z surface analysis showed an elongated area of low pressure from southern WI to northwestern MO, with cold front through central OK and north-central/central TX. The front was preceded by an extensive convective band and associated outflow boundary from central IL to central AR, east TX, and deep south TX. By 00Z, the front should catch up (or nearly so) to what remains of the convective boundary, with the combined baroclinic zone extending from a consolidated low over northern WI across the Mid-South region to the northwestern Gulf shelf waters off TX. By 12Z, the front should extend from Lower MI across western portions of KY/TN/MS to southwestern LA and the northwestern Gulf. ...Sabine to Lower Mississippi Valleys... The ongoing convective band, near the western edge of the "Marginal Risk" area, should weaken overall through mid-morning. However, an isolated damaging gust or brief tornado cannot be ruled out in the meantime with any associated or preceding cell that may take advantage of lingering favorable deep shear and high theta-e, in a northward-narrowing corridor. After a relative lull of a few hours, widely scattered to scattered thunderstorms are forecast along the boundary this afternoon into early evening, with isolated damaging gusts and/or a tornado possible. Afternoon boundary-layer destabilization is anticipated ahead of the convective boundary, from both fragmented/cloud- modulated surface heating and low-level theta-e advection. A corridor of surface dewpoints in the upper 60s to low 70s F will persist an expand slightly northward ahead of the boundary. With no antecedent EML and minimal MLCINH, this should offset modest midlevel lapse rates enough to result in effectively uninhibited buoyancy, supporting an increase in convective coverage and local intensity this afternoon. Peak MLCAPE should range from around 500-800 J/kg over a narrow corridor of the Mid-South, widening/increasing to around 1000-1500 J/kg over southern LA. By contrast, lift along the boundary, and in the form of deep-layer ascent preceding the weakening mid/upper trough, will be greater over the Mid-South, until some nebulous point where too little instability exists to support organized convection. The outlook has been elongated northward somewhat to cover the marginal-buoyancy plume near the Mississippi River. ...WI... Isolated to widely scattered, shallow thunderstorms are possible this afternoon, in an arc near the front and the organizing surface low. A few cells may produce damaging gusts. A brief tornado also may occur, especially with any cells that can linger within a narrow zone of overlap between favorably, isallobarically backed near- surface winds and weak boundary-layer instability. A low-confidence and quite conditional scenario exists here, with abundant antecedent clouds and precip likely to limit destabilization for most of the day. Forecast soundings suggest enough large-scale ascent aloft to cool midlevels a degree or two C, though lapse rates still will be meager. Areas that can experience a couple hours of relatively unimpeded heating may attain 250-500 J/kg MLCAPE. ..Edwards/Mosier.. 11/05/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0650 AM CST Tue Nov 05 2024 Valid 051300Z - 061200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS A PORTION OF THE SABINE TO LOWER MISSISSIPPI VALLEYS...AND CENTRAL TO SOUTHERN WISCONSIN... ...SUMMARY... A brief tornado or two and locally damaging winds may occur across a portion of the Sabine to Lower Mississippi Valleys, and central to southern Wisconsin. ...Synopsis... Mid/upper-level longwave troughing has become well-established over the western CONUS. That will persist through this and more outlook periods, as a series of synoptic to large shortwave troughs traverses the associated cyclonic-flow field. The leading such perturbation -- now located from the central Plains south- southwestward over the southern High Plains to far west TX -- will eject northeastward and weaken. By 00Z, the residual, strongly positively tilted trough should extend from a vorticity max over western WI, across central/southwestern MO to central TX. The perturbation will deamplify greatly overnight and accelerate to a position near the western QC/ON border, Lake Huron and IN by 12Z. Meanwhile, an upstream shortwave trough -- evident in moisture- channel imagery over ID -- will dig southeastward and strengthen greatly through the period. By 12Z, it should be oriented northeast/southwest through a developing 500-mb low over the Four Corners. The 11Z surface analysis showed an elongated area of low pressure from southern WI to northwestern MO, with cold front through central OK and north-central/central TX. The front was preceded by an extensive convective band and associated outflow boundary from central IL to central AR, east TX, and deep south TX. By 00Z, the front should catch up (or nearly so) to what remains of the convective boundary, with the combined baroclinic zone extending from a consolidated low over northern WI across the Mid-South region to the northwestern Gulf shelf waters off TX. By 12Z, the front should extend from Lower MI across western portions of KY/TN/MS to southwestern LA and the northwestern Gulf. ...Sabine to Lower Mississippi Valleys... The ongoing convective band, near the western edge of the "Marginal Risk" area, should weaken overall through mid-morning. However, an isolated damaging gust or brief tornado cannot be ruled out in the meantime with any associated or preceding cell that may take advantage of lingering favorable deep shear and high theta-e, in a northward-narrowing corridor. After a relative lull of a few hours, widely scattered to scattered thunderstorms are forecast along the boundary this afternoon into early evening, with isolated damaging gusts and/or a tornado possible. Afternoon boundary-layer destabilization is anticipated ahead of the convective boundary, from both fragmented/cloud- modulated surface heating and low-level theta-e advection. A corridor of surface dewpoints in the upper 60s to low 70s F will persist an expand slightly northward ahead of the boundary. With no antecedent EML and minimal MLCINH, this should offset modest midlevel lapse rates enough to result in effectively uninhibited buoyancy, supporting an increase in convective coverage and local intensity this afternoon. Peak MLCAPE should range from around 500-800 J/kg over a narrow corridor of the Mid-South, widening/increasing to around 1000-1500 J/kg over southern LA. By contrast, lift along the boundary, and in the form of deep-layer ascent preceding the weakening mid/upper trough, will be greater over the Mid-South, until some nebulous point where too little instability exists to support organized convection. The outlook has been elongated northward somewhat to cover the marginal-buoyancy plume near the Mississippi River. ...WI... Isolated to widely scattered, shallow thunderstorms are possible this afternoon, in an arc near the front and the organizing surface low. A few cells may produce damaging gusts. A brief tornado also may occur, especially with any cells that can linger within a narrow zone of overlap between favorably, isallobarically backed near- surface winds and weak boundary-layer instability. A low-confidence and quite conditional scenario exists here, with abundant antecedent clouds and precip likely to limit destabilization for most of the day. Forecast soundings suggest enough large-scale ascent aloft to cool midlevels a degree or two C, though lapse rates still will be meager. Areas that can experience a couple hours of relatively unimpeded heating may attain 250-500 J/kg MLCAPE. ..Edwards/Mosier.. 11/05/2024 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0337 AM CST Tue Nov 05 2024 Valid 081200Z - 131200Z ...DISCUSSION... ...D4-5/Friday-Saturday... Guidance suggests acceleration of the Southwest upper trough should occur across the southern High Plains to central Great Plains. After an initially inverted surface trough on D3/Thursday, surface cyclone development is expected. Overall model trends have been for greater amplification of the trough and attendant surface reflection. But spatial spread, that is noticeable on Thursday, increases further into Friday-Saturday. In addition, very large spread persists with the potential track of TC Rafael in the Gulf. This may render peripheral impacts on the surrounding low-level moisture plume ahead of the Great Plains wave. As such, confidence is low for determining probable mesoscale-focused severe potential on D4-5 across the south-central states. ...D8/Tuesday... After a potential quiet period of severe potential on D6-7, guidance consensus indicates an amplified upper trough should progress into the West early next week. This may eventually overlap a broadening warm/moist sector emanating north from the western Gulf and yield a return to increasing severe potential towards mid-week. Poor run-to-run continuity and large ensemble spread exists with the evolution of this trough for now. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0337 AM CST Tue Nov 05 2024 Valid 081200Z - 131200Z ...DISCUSSION... ...D4-5/Friday-Saturday... Guidance suggests acceleration of the Southwest upper trough should occur across the southern High Plains to central Great Plains. After an initially inverted surface trough on D3/Thursday, surface cyclone development is expected. Overall model trends have been for greater amplification of the trough and attendant surface reflection. But spatial spread, that is noticeable on Thursday, increases further into Friday-Saturday. In addition, very large spread persists with the potential track of TC Rafael in the Gulf. This may render peripheral impacts on the surrounding low-level moisture plume ahead of the Great Plains wave. As such, confidence is low for determining probable mesoscale-focused severe potential on D4-5 across the south-central states. ...D8/Tuesday... After a potential quiet period of severe potential on D6-7, guidance consensus indicates an amplified upper trough should progress into the West early next week. This may eventually overlap a broadening warm/moist sector emanating north from the western Gulf and yield a return to increasing severe potential towards mid-week. Poor run-to-run continuity and large ensemble spread exists with the evolution of this trough for now. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0337 AM CST Tue Nov 05 2024 Valid 081200Z - 131200Z ...DISCUSSION... ...D4-5/Friday-Saturday... Guidance suggests acceleration of the Southwest upper trough should occur across the southern High Plains to central Great Plains. After an initially inverted surface trough on D3/Thursday, surface cyclone development is expected. Overall model trends have been for greater amplification of the trough and attendant surface reflection. But spatial spread, that is noticeable on Thursday, increases further into Friday-Saturday. In addition, very large spread persists with the potential track of TC Rafael in the Gulf. This may render peripheral impacts on the surrounding low-level moisture plume ahead of the Great Plains wave. As such, confidence is low for determining probable mesoscale-focused severe potential on D4-5 across the south-central states. ...D8/Tuesday... After a potential quiet period of severe potential on D6-7, guidance consensus indicates an amplified upper trough should progress into the West early next week. This may eventually overlap a broadening warm/moist sector emanating north from the western Gulf and yield a return to increasing severe potential towards mid-week. Poor run-to-run continuity and large ensemble spread exists with the evolution of this trough for now. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0337 AM CST Tue Nov 05 2024 Valid 081200Z - 131200Z ...DISCUSSION... ...D4-5/Friday-Saturday... Guidance suggests acceleration of the Southwest upper trough should occur across the southern High Plains to central Great Plains. After an initially inverted surface trough on D3/Thursday, surface cyclone development is expected. Overall model trends have been for greater amplification of the trough and attendant surface reflection. But spatial spread, that is noticeable on Thursday, increases further into Friday-Saturday. In addition, very large spread persists with the potential track of TC Rafael in the Gulf. This may render peripheral impacts on the surrounding low-level moisture plume ahead of the Great Plains wave. As such, confidence is low for determining probable mesoscale-focused severe potential on D4-5 across the south-central states. ...D8/Tuesday... After a potential quiet period of severe potential on D6-7, guidance consensus indicates an amplified upper trough should progress into the West early next week. This may eventually overlap a broadening warm/moist sector emanating north from the western Gulf and yield a return to increasing severe potential towards mid-week. Poor run-to-run continuity and large ensemble spread exists with the evolution of this trough for now. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0337 AM CST Tue Nov 05 2024 Valid 081200Z - 131200Z ...DISCUSSION... ...D4-5/Friday-Saturday... Guidance suggests acceleration of the Southwest upper trough should occur across the southern High Plains to central Great Plains. After an initially inverted surface trough on D3/Thursday, surface cyclone development is expected. Overall model trends have been for greater amplification of the trough and attendant surface reflection. But spatial spread, that is noticeable on Thursday, increases further into Friday-Saturday. In addition, very large spread persists with the potential track of TC Rafael in the Gulf. This may render peripheral impacts on the surrounding low-level moisture plume ahead of the Great Plains wave. As such, confidence is low for determining probable mesoscale-focused severe potential on D4-5 across the south-central states. ...D8/Tuesday... After a potential quiet period of severe potential on D6-7, guidance consensus indicates an amplified upper trough should progress into the West early next week. This may eventually overlap a broadening warm/moist sector emanating north from the western Gulf and yield a return to increasing severe potential towards mid-week. Poor run-to-run continuity and large ensemble spread exists with the evolution of this trough for now. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0337 AM CST Tue Nov 05 2024 Valid 081200Z - 131200Z ...DISCUSSION... ...D4-5/Friday-Saturday... Guidance suggests acceleration of the Southwest upper trough should occur across the southern High Plains to central Great Plains. After an initially inverted surface trough on D3/Thursday, surface cyclone development is expected. Overall model trends have been for greater amplification of the trough and attendant surface reflection. But spatial spread, that is noticeable on Thursday, increases further into Friday-Saturday. In addition, very large spread persists with the potential track of TC Rafael in the Gulf. This may render peripheral impacts on the surrounding low-level moisture plume ahead of the Great Plains wave. As such, confidence is low for determining probable mesoscale-focused severe potential on D4-5 across the south-central states. ...D8/Tuesday... After a potential quiet period of severe potential on D6-7, guidance consensus indicates an amplified upper trough should progress into the West early next week. This may eventually overlap a broadening warm/moist sector emanating north from the western Gulf and yield a return to increasing severe potential towards mid-week. Poor run-to-run continuity and large ensemble spread exists with the evolution of this trough for now. Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0222 AM CST Tue Nov 05 2024 Valid 071200Z - 081200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN PARTS OF CENTRAL/WEST-CENTRAL TX... ...SUMMARY... Isolated severe thunderstorms are possible, beginning Thursday afternoon across central/west-central parts of Texas. ...TX... Modified moisture return from the western Gulf will increase across much of TX in advance of a slow-moving mid/upper trough over AZ/NM. A surface anticyclone over the central High Plains will support ridging southward across the southern High Plains, with an inverted trough developing to its east. 00Z models differ substantially in the location of this trough, largely bracketed by a farther east GFS and west ECMWF. This yields longitudinal uncertainty with the potential severe-storm corridor. Much of the convective development will probably be elevated to the cool side of the surface trough. Even so, a threat for severe hail should exist given favorably strong southwesterly speed shear. Surface-based buoyancy should struggle to develop north/west of central TX, ahead of the inverted trough. This may be adequate for a confined corridor of surface-based supercell threat starting Thursday afternoon. Given the spatial uncertainties and relatively nebulous setup, only low severe probabilities appear warranted. ...Central/eastern Gulf Coast... Per the latest NHC forecast and probable compact nature of strong low-level winds surrounding TC Rafael, a coastal tornado threat appears unlikely on Thursday to early Friday. Still, with large spread in guidance regarding the evolution of TC Rafael in the eastern to central Gulf, there remains potential for a tornado-threat highlight during this time frame in later outlooks. ..Grams.. 11/05/2024 Read more