SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1223 PM CDT Wed Aug 28 2024 Valid 291200Z - 301200Z ...NO CRITICAL AREAS... The previous forecast (see below) remains on track. ..Weinman.. 08/28/2024 .PREV DISCUSSION... /ISSUED 0152 AM CDT Wed Aug 28 2024/ ...Synopsis... Upper ridging will build over the Interior West as a mid-level trough impinges on the Upper Mississippi Valley tomorrow (Thursday). As a result, surface high pressure and associated quiescent fire weather conditions will settle over the northern Rockies into the Great Basin and Four Corners regions. 15-25 percent RH will be common across much of the Intermountain West by afternoon peak heating, with stronger gusts most likely in localized, terrain-favoring areas. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1223 PM CDT Wed Aug 28 2024 Valid 291200Z - 301200Z ...NO CRITICAL AREAS... The previous forecast (see below) remains on track. ..Weinman.. 08/28/2024 .PREV DISCUSSION... /ISSUED 0152 AM CDT Wed Aug 28 2024/ ...Synopsis... Upper ridging will build over the Interior West as a mid-level trough impinges on the Upper Mississippi Valley tomorrow (Thursday). As a result, surface high pressure and associated quiescent fire weather conditions will settle over the northern Rockies into the Great Basin and Four Corners regions. 15-25 percent RH will be common across much of the Intermountain West by afternoon peak heating, with stronger gusts most likely in localized, terrain-favoring areas. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1141 AM CDT Wed Aug 28 2024 Valid 281700Z - 291200Z The previous forecast (see below) remains on track, and no changes were needed with this update. ..Weinman.. 08/28/2024 .PREV DISCUSSION... /ISSUED 0149 AM CDT Wed Aug 28 2024/ ...Synopsis... A mid-level trough will traverse the northern Rockies today, encouraging strong surface lee troughing over the northern Plains. By afternoon, isallobaric and downslope flow will promote dry and windy conditions over portions of the central and northern Rockies. 15-25 mph sustained west-southwesterly surface winds will overlap with 15-20 percent RH, from portions of southeast Montana into central Wyoming. Elevated highlights have been maintained in central Wyoming, where dry and windy conditions will best overlap with fuels that are at least marginally receptive to wildfire spread. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1141 AM CDT Wed Aug 28 2024 Valid 281700Z - 291200Z The previous forecast (see below) remains on track, and no changes were needed with this update. ..Weinman.. 08/28/2024 .PREV DISCUSSION... /ISSUED 0149 AM CDT Wed Aug 28 2024/ ...Synopsis... A mid-level trough will traverse the northern Rockies today, encouraging strong surface lee troughing over the northern Plains. By afternoon, isallobaric and downslope flow will promote dry and windy conditions over portions of the central and northern Rockies. 15-25 mph sustained west-southwesterly surface winds will overlap with 15-20 percent RH, from portions of southeast Montana into central Wyoming. Elevated highlights have been maintained in central Wyoming, where dry and windy conditions will best overlap with fuels that are at least marginally receptive to wildfire spread. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1136 AM CDT Wed Aug 28 2024 Valid 281630Z - 291200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTH DAKOTA/SOUTH DAKOTA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDWEST/OHIO VALLEY TO MID-ATLANTIC... ...SUMMARY... Severe thunderstorms are expected across parts of the Dakotas and from the Ohio Valley to the Mid-Atlantic Coast. ...Dakotas... Have upgraded portions of south-central North Dakota/north-central South Dakota to a categorical Enhanced Risk for what should be a relatively greater likelihood and concentration of severe storms late this afternoon through early/mid-evening. A prominent upper-level trough centered over western Montana and southern Alberta will continue generally eastward over the Canadian Prairies and toward the northern High Plains, with a trough-preceding/basal upper-level jet resulting in considerably strengthening southwesterly winds aloft by peak heating into tonight. This will be atop an increasingly moist boundary layer (dewpoints increasing through the 60s F) ahead of a surface low across South Dakota and a front extending northward into North Dakota. Thunderstorms should develop near the front by late afternoon/early evening, perhaps initially across North Dakota where overall forcing will be greater, and subsequently southward into South Dakota where richer low-level moisture and greater buoyancy will reside. Given steep lapse rates and the reservoir of instability, these initial storms should be supercells capable of very large hail amidst strengthening flow aloft. Large to very large hail and severe wind gusts will be the most common hazards, although a tornado risk may also exist particularly across north-central South Dakota/far south-central North Dakota near the surface low/warm front-related triple point where moisture/low-level SRH will be maximized. Over time, relatively weak mid-level flow may encourage a transition to messier, quasi-linear modes with embedded LEWP/bow formations for a few hours. Activity should weaken overnight as it moves into stabilizing boundary-layer air, though a 45-55-kt low-level jet may encourage persistence of a cluster or two tonight into the eastern Dakotas. ...Midwest/Ohio Valley to Mid-Atlantic States... Widely scattered to scattered thunderstorms will pose a risk for damaging winds particularly mid/late afternoon through early/mid-evening regionally. Some hail may also occur on a more marginal and isolated basis. This severe risk will primarily span parts of Indiana/Ohio eastward to the coastal Mid-Atlantic/Delmarva vicinity, although the overall extent and magnitude of today's risk is still a bit uncertain. The boundary layer will not be overly moist by late-summer standards, particularly across the middle Ohio River Valley, but a relatively richer moist axis (through the lowest 2-3 km AGL) extends this morning from the upper Ohio Valley eastward toward the coastal Mid-Atlantic/Northeast. The boundary layer will also not be overly unstable later today, with severe-adequate MLCAPE generally limited to 2000 J/kg MLCAPE. Aside from differential heating related to last night's convection across the Midwest, several impetuses for thunderstorm development to the south of the primary Great Lakes front may include the eastward transitions of MCVs across southeast Lower Michigan and north-central Illinois, which should be influential into the Lake Ontario/New York/northern Pennsylvania and lower/middle Ohio Valley vicinities, respectively, later this afternoon and evening. Effective shear will tend to be limited to 20-25 kt, but slowly-increasing-with-height deep-layer westerlies will support multicell-related damaging wind/some hail potential as low-level lapse rates steepen and the boundary layer moderately destabilizes this afternoon. ..Guyer/Wendt.. 08/28/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1136 AM CDT Wed Aug 28 2024 Valid 281630Z - 291200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTH DAKOTA/SOUTH DAKOTA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDWEST/OHIO VALLEY TO MID-ATLANTIC... ...SUMMARY... Severe thunderstorms are expected across parts of the Dakotas and from the Ohio Valley to the Mid-Atlantic Coast. ...Dakotas... Have upgraded portions of south-central North Dakota/north-central South Dakota to a categorical Enhanced Risk for what should be a relatively greater likelihood and concentration of severe storms late this afternoon through early/mid-evening. A prominent upper-level trough centered over western Montana and southern Alberta will continue generally eastward over the Canadian Prairies and toward the northern High Plains, with a trough-preceding/basal upper-level jet resulting in considerably strengthening southwesterly winds aloft by peak heating into tonight. This will be atop an increasingly moist boundary layer (dewpoints increasing through the 60s F) ahead of a surface low across South Dakota and a front extending northward into North Dakota. Thunderstorms should develop near the front by late afternoon/early evening, perhaps initially across North Dakota where overall forcing will be greater, and subsequently southward into South Dakota where richer low-level moisture and greater buoyancy will reside. Given steep lapse rates and the reservoir of instability, these initial storms should be supercells capable of very large hail amidst strengthening flow aloft. Large to very large hail and severe wind gusts will be the most common hazards, although a tornado risk may also exist particularly across north-central South Dakota/far south-central North Dakota near the surface low/warm front-related triple point where moisture/low-level SRH will be maximized. Over time, relatively weak mid-level flow may encourage a transition to messier, quasi-linear modes with embedded LEWP/bow formations for a few hours. Activity should weaken overnight as it moves into stabilizing boundary-layer air, though a 45-55-kt low-level jet may encourage persistence of a cluster or two tonight into the eastern Dakotas. ...Midwest/Ohio Valley to Mid-Atlantic States... Widely scattered to scattered thunderstorms will pose a risk for damaging winds particularly mid/late afternoon through early/mid-evening regionally. Some hail may also occur on a more marginal and isolated basis. This severe risk will primarily span parts of Indiana/Ohio eastward to the coastal Mid-Atlantic/Delmarva vicinity, although the overall extent and magnitude of today's risk is still a bit uncertain. The boundary layer will not be overly moist by late-summer standards, particularly across the middle Ohio River Valley, but a relatively richer moist axis (through the lowest 2-3 km AGL) extends this morning from the upper Ohio Valley eastward toward the coastal Mid-Atlantic/Northeast. The boundary layer will also not be overly unstable later today, with severe-adequate MLCAPE generally limited to 2000 J/kg MLCAPE. Aside from differential heating related to last night's convection across the Midwest, several impetuses for thunderstorm development to the south of the primary Great Lakes front may include the eastward transitions of MCVs across southeast Lower Michigan and north-central Illinois, which should be influential into the Lake Ontario/New York/northern Pennsylvania and lower/middle Ohio Valley vicinities, respectively, later this afternoon and evening. Effective shear will tend to be limited to 20-25 kt, but slowly-increasing-with-height deep-layer westerlies will support multicell-related damaging wind/some hail potential as low-level lapse rates steepen and the boundary layer moderately destabilizes this afternoon. ..Guyer/Wendt.. 08/28/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Wed Aug 28 2024 Valid 281300Z - 291200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OHIO VALLEY TO THE NORTHERN MID-ATLANTIC COAST...AND ACROSS PARTS OF NORTH AND SOUTH DAKOTA... ...SUMMARY... Severe thunderstorms are expected from the Ohio Valley to the northern Mid-Atlantic Coast, and across parts of North and South Dakota. ...Synopsis... In mid/upper levels, a progressive northern-stream pattern will prevail through the period, with the main feature being a cyclone now apparent in moisture-channel imagery near the southeastern corner of BC. The associated 500-mb low should move eastward roughly along, or just north of, the international border through the period, with the accompanying trough extending south- southwestward. By 00Z, the low should be near the southwestern corner of SK, with trough to northern UT. By 12Z, the low should reach extreme south-central SK, with trough across central MT to southwestern WY. Downstream, a complex but much lower-amplitude shortwave trough was evident over Lake Superior and adjoining portions of ON and western U.P. of MI. One part of this perturbation should break eastward to the St. Lawrence Valley by the end of the period, while the trailing part drifts eastward over Lake Superior and the U.P. Of perhaps greater direct influence on convective potential, an MCV was apparent in composited radar imagery over southeastern IA. The associated perturbation should move across much of central IL today, reaching western OH by 12Z tomorrow. The 11Z surface analysis showed a cold front from northern ME west- southwestward across Lake Ontario and southern Lower MI, becoming quasistationary for the time being across southern parts of Lake Michigan and WI, to northeastern NE, then a warm front over southwestern SD, to a low over southeastern MT. This front is expected to move southeastward by 00Z to coastal NS, Cape Cod, Long Island, northern parts of MD/WV, and southern parts of OH/IN/IL, becoming a diffuse warm front northwestward over central IA, southwestern MN and central ND. There it will be overtaken by another cold front -- initially analyzed through the low over eastern MT and across northwestern WY. By 00Z, this second, stronger cold front should extend from central ND across central/ southwestern SD to east-central WY. By 12Z, the western cold front should extend from a low over southeastern ND or northeastern SD across south-central SD, western NE and northeastern CO. ...Ohio Valley to Mid-Atlantic... Widely scattered to scattered thunderstorms are expected along and south of the front today from IN to the Mid-Atlantic Coast, and perhaps the southern New England Coast/Long Island vicinity. Damaging gusts and isolated large hail will be possible. Coverage of convection is uncertain, but relative concentrations may develop downshear from what is now disorganized/nonsevere convection over OH (in the same UVV field), and ahead of the MCV over parts of IL/IN, becoming organized across parts of IN/OH. Diurnal heating of a favorably moist airmass is expected to weaken already modest ambient MLCINH along the outlook corridor by late morning. With lift along the front and prefrontal outflow/differential-heating boundaries, growth of morning to early afternoon development into one or more complexes appears to be a plausible scenario, rendering a greater wind than hail threat. Surface dewpoints commonly in the mid 60s to low 70s F will offset modest mid/upper-level lapse rates enough to contribute to peak/preconvective MLCAPE in the 800-1500 J/kg range from OH eastward, and 1000-2000 J/kg back into portions of IN. Weak, generally veered low/middle-level flow will limit vertical shear. Still, nearly unidirectional westerly flow through a deep layer will foster movement of convection parallel to the low-level moisture-instability axis. ...Dakotas... A line or arc of scattered thunderstorms should develop along/near the cold front during late afternoon into evening, perhaps initially over ND where deep-layer forcing will be stronger, then southward into greater capping in SD, as the front impinges on greater moisture and lingering boundary-layer instability. Ahead of the cold front, enough easterly component to near-surface flow will develop to support moist advection into the convective genesis zone, with surface dewpoints into the 60s F becoming common. Capping at the base of a modest EML will suppress development for much of the afternoon, especially over SD, but once frontal lift overcomes it, a corridor of 2000-3000 J/kg MLCAPE should be available southwest of (and parallel to) the warm front. Though the strongest flow aloft and large-scale ascent will remain behind the cold front, the eastern rim of stronger height falls will spread over the frontal zone, with enough mass response to both foster favorable vertical shear for supercells and enhanced storm-relative flow in low levels. Effective-shear magnitudes of 30-40 kt (locally higher) and broad low-level hodographs along and south of the warm front should foster supercell development, until mergers and upscale growth occur. Large to very large hail and severe gusts will be the main concerns, though a tornado is possible. However, relatively weak midlevel flow may encourage a transition to messier, quasi- linear mode with embedded LEWP/bow formations for a few hours. Activity should weaken overnight as it moves into stabilizing boundary-layer air, though a 45-55-kt LLJ may encourage persistence of a cluster or two tonight into the eastern Dakotas. ..Edwards/Bentley.. 08/28/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Wed Aug 28 2024 Valid 281300Z - 291200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OHIO VALLEY TO THE NORTHERN MID-ATLANTIC COAST...AND ACROSS PARTS OF NORTH AND SOUTH DAKOTA... ...SUMMARY... Severe thunderstorms are expected from the Ohio Valley to the northern Mid-Atlantic Coast, and across parts of North and South Dakota. ...Synopsis... In mid/upper levels, a progressive northern-stream pattern will prevail through the period, with the main feature being a cyclone now apparent in moisture-channel imagery near the southeastern corner of BC. The associated 500-mb low should move eastward roughly along, or just north of, the international border through the period, with the accompanying trough extending south- southwestward. By 00Z, the low should be near the southwestern corner of SK, with trough to northern UT. By 12Z, the low should reach extreme south-central SK, with trough across central MT to southwestern WY. Downstream, a complex but much lower-amplitude shortwave trough was evident over Lake Superior and adjoining portions of ON and western U.P. of MI. One part of this perturbation should break eastward to the St. Lawrence Valley by the end of the period, while the trailing part drifts eastward over Lake Superior and the U.P. Of perhaps greater direct influence on convective potential, an MCV was apparent in composited radar imagery over southeastern IA. The associated perturbation should move across much of central IL today, reaching western OH by 12Z tomorrow. The 11Z surface analysis showed a cold front from northern ME west- southwestward across Lake Ontario and southern Lower MI, becoming quasistationary for the time being across southern parts of Lake Michigan and WI, to northeastern NE, then a warm front over southwestern SD, to a low over southeastern MT. This front is expected to move southeastward by 00Z to coastal NS, Cape Cod, Long Island, northern parts of MD/WV, and southern parts of OH/IN/IL, becoming a diffuse warm front northwestward over central IA, southwestern MN and central ND. There it will be overtaken by another cold front -- initially analyzed through the low over eastern MT and across northwestern WY. By 00Z, this second, stronger cold front should extend from central ND across central/ southwestern SD to east-central WY. By 12Z, the western cold front should extend from a low over southeastern ND or northeastern SD across south-central SD, western NE and northeastern CO. ...Ohio Valley to Mid-Atlantic... Widely scattered to scattered thunderstorms are expected along and south of the front today from IN to the Mid-Atlantic Coast, and perhaps the southern New England Coast/Long Island vicinity. Damaging gusts and isolated large hail will be possible. Coverage of convection is uncertain, but relative concentrations may develop downshear from what is now disorganized/nonsevere convection over OH (in the same UVV field), and ahead of the MCV over parts of IL/IN, becoming organized across parts of IN/OH. Diurnal heating of a favorably moist airmass is expected to weaken already modest ambient MLCINH along the outlook corridor by late morning. With lift along the front and prefrontal outflow/differential-heating boundaries, growth of morning to early afternoon development into one or more complexes appears to be a plausible scenario, rendering a greater wind than hail threat. Surface dewpoints commonly in the mid 60s to low 70s F will offset modest mid/upper-level lapse rates enough to contribute to peak/preconvective MLCAPE in the 800-1500 J/kg range from OH eastward, and 1000-2000 J/kg back into portions of IN. Weak, generally veered low/middle-level flow will limit vertical shear. Still, nearly unidirectional westerly flow through a deep layer will foster movement of convection parallel to the low-level moisture-instability axis. ...Dakotas... A line or arc of scattered thunderstorms should develop along/near the cold front during late afternoon into evening, perhaps initially over ND where deep-layer forcing will be stronger, then southward into greater capping in SD, as the front impinges on greater moisture and lingering boundary-layer instability. Ahead of the cold front, enough easterly component to near-surface flow will develop to support moist advection into the convective genesis zone, with surface dewpoints into the 60s F becoming common. Capping at the base of a modest EML will suppress development for much of the afternoon, especially over SD, but once frontal lift overcomes it, a corridor of 2000-3000 J/kg MLCAPE should be available southwest of (and parallel to) the warm front. Though the strongest flow aloft and large-scale ascent will remain behind the cold front, the eastern rim of stronger height falls will spread over the frontal zone, with enough mass response to both foster favorable vertical shear for supercells and enhanced storm-relative flow in low levels. Effective-shear magnitudes of 30-40 kt (locally higher) and broad low-level hodographs along and south of the warm front should foster supercell development, until mergers and upscale growth occur. Large to very large hail and severe gusts will be the main concerns, though a tornado is possible. However, relatively weak midlevel flow may encourage a transition to messier, quasi- linear mode with embedded LEWP/bow formations for a few hours. Activity should weaken overnight as it moves into stabilizing boundary-layer air, though a 45-55-kt LLJ may encourage persistence of a cluster or two tonight into the eastern Dakotas. ..Edwards/Bentley.. 08/28/2024 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Wed Aug 28 2024 Valid 311200Z - 051200Z ...DISCUSSION... Medium-range global models continue to suggest limited severe potential Days 4-5 (Saturday and Sunday) largely within the northeastern quarter of the country, followed by several days of what appears likely to be minimal severe risk through the remainder of the period. Day 4/Saturday, upper-level height falls are progged to shift across the Great Lakes/Midwest/Northeast, as a strengthening upper trough advances east-southeastward across Ontario and the Upper Great Lakes region. A weak cold front will cross the Lower Great Lakes/Appalachians, with likelihood for showers and thunderstorms accompanying this front. However, with stronger flow aloft limited to areas from Pennsylvania northward, where instability should remain limited, overall severe risk appears at this time to remain too low to warrant inclusion of a risk area associated with this frontal passage. Limited severe potential may also exist for a few hours in the afternoon and early evening over the Upper Mississippi Valley area, as a stronger/reinforcing cold front surges southeastward out of Canada across the Upper Mississippi Valley and Great Lakes region and into central Plains and Upper Midwest overnight. Though only modest moisture -- and thus weak afternoon pre-frontal destabilization -- is expected, low-topped convection is expected during the afternoon across parts of Upper Michigan/Wisconsin and perhaps Minnesota. Strong northwesterly flow aloft would support fast-moving storms, and possibly a risk for damaging winds locally. Again though, this potential appears too limited/uncertain to include a risk area at this time. Day 5, the surging cold front is forecast to shift southeastward into the Northeast/New England, and southward across the Ohio Valley area. Similar to Day 4 potential for low-topped storms farther northwest, convection will likely develop along the front through the afternoon -- particularly across the New England vicinity. However, given the frontal passage the prior day, questions with respect to available moisture -- and thus destabilization potential -- exist at this time. As such, despite the strong front and strong flow aloft, severe risk again appears limited and uncertain, precluding introduction of a risk area for now. The cold front is expected to have moved offshore of New England and the Mid-Atlantic region by the start of Day 6, becoming quasistationary in a west-to-east manner across the Southeast and Mid South, on the southern fringe of a Canadian High settling into the northeastern quarter of the country. While convection will likely occur near and south of this front where moist Gulf air will remain in place, this region will remain well south of the enhanced flow aloft. Therefore, severe risk appears minimal -- and should remain so through the end of the period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Wed Aug 28 2024 Valid 311200Z - 051200Z ...DISCUSSION... Medium-range global models continue to suggest limited severe potential Days 4-5 (Saturday and Sunday) largely within the northeastern quarter of the country, followed by several days of what appears likely to be minimal severe risk through the remainder of the period. Day 4/Saturday, upper-level height falls are progged to shift across the Great Lakes/Midwest/Northeast, as a strengthening upper trough advances east-southeastward across Ontario and the Upper Great Lakes region. A weak cold front will cross the Lower Great Lakes/Appalachians, with likelihood for showers and thunderstorms accompanying this front. However, with stronger flow aloft limited to areas from Pennsylvania northward, where instability should remain limited, overall severe risk appears at this time to remain too low to warrant inclusion of a risk area associated with this frontal passage. Limited severe potential may also exist for a few hours in the afternoon and early evening over the Upper Mississippi Valley area, as a stronger/reinforcing cold front surges southeastward out of Canada across the Upper Mississippi Valley and Great Lakes region and into central Plains and Upper Midwest overnight. Though only modest moisture -- and thus weak afternoon pre-frontal destabilization -- is expected, low-topped convection is expected during the afternoon across parts of Upper Michigan/Wisconsin and perhaps Minnesota. Strong northwesterly flow aloft would support fast-moving storms, and possibly a risk for damaging winds locally. Again though, this potential appears too limited/uncertain to include a risk area at this time. Day 5, the surging cold front is forecast to shift southeastward into the Northeast/New England, and southward across the Ohio Valley area. Similar to Day 4 potential for low-topped storms farther northwest, convection will likely develop along the front through the afternoon -- particularly across the New England vicinity. However, given the frontal passage the prior day, questions with respect to available moisture -- and thus destabilization potential -- exist at this time. As such, despite the strong front and strong flow aloft, severe risk again appears limited and uncertain, precluding introduction of a risk area for now. The cold front is expected to have moved offshore of New England and the Mid-Atlantic region by the start of Day 6, becoming quasistationary in a west-to-east manner across the Southeast and Mid South, on the southern fringe of a Canadian High settling into the northeastern quarter of the country. While convection will likely occur near and south of this front where moist Gulf air will remain in place, this region will remain well south of the enhanced flow aloft. Therefore, severe risk appears minimal -- and should remain so through the end of the period. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0229 AM CDT Wed Aug 28 2024 Valid 301200Z - 311200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM LAKES HUDSON AND ERIE WEST-SOUTHWESTWARD ACROSS THE MIDWEST... ...SUMMARY... Strong/locally severe storms will be posible from Lakes Huron and Erie southwesteward into the Midwest Friday. ...Synopsis... An upper trough will continue moving slowly eastward out of the north-central U.S. across the Great Lakes and Midwest on Friday, though the more vigorous portion of the trough is forecast to eject northeastward across Ontario into the Hudson Bay region. At the surface, a cold front is forecast to continue eastward across the Great Lakes region, southeastward across the Midwest, and southward across the Plains. By the end of the period, the front should extend from the Lower Great Lakes west-southwestward across the Ohio Valley, and into Oklahoma and northern Texas. ...Lower Michigan/northern Ohio/northwestern Pennsylvania across the Midwest... Afternoon destabilization across the Midwest ahead of the advancing cold front will support development of scattered thunderstorms. While stronger flow aloft will remain to the cool side of the front, moderate low- to mid-level westerlies extending south into the Midwest states should allow a few stronger storms to evolve, including a few small clusters/line segments. The strongest storms will pose some risk for marginal hail and wind gusts capable of mainly tree damage, into the evening hours before a nocturnal convective decrease commences. ..Goss.. 08/28/2024 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0152 AM CDT Wed Aug 28 2024 Valid 291200Z - 301200Z ...NO CRITICAL AREAS... ...Synopsis... Upper ridging will build over the Interior West as a mid-level trough impinges on the Upper Mississippi Valley tomorrow (Thursday). As a result, surface high pressure and associated quiescent fire weather conditions will settle over the northern Rockies into the Great Basin and Four Corners regions. 15-25 percent RH will be common across much of the Intermountain West by afternoon peak heating, with stronger gusts most likely in localized, terrain-favoring areas. ..Squitieri.. 08/28/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0149 AM CDT Wed Aug 28 2024 Valid 281200Z - 291200Z ...Synopsis... A mid-level trough will traverse the northern Rockies today, encouraging strong surface lee troughing over the northern Plains. By afternoon, isallobaric and downslope flow will promote dry and windy conditions over portions of the central and northern Rockies. 15-25 mph sustained west-southwesterly surface winds will overlap with 15-20 percent RH, from portions of southeast Montana into central Wyoming. Elevated highlights have been maintained in central Wyoming, where dry and windy conditions will best overlap with fuels that are at least marginally receptive to wildfire spread. ..Squitieri.. 08/28/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0104 AM CDT Wed Aug 28 2024 Valid 291200Z - 301200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF MINNESOTA AND WESTERN WISCONSIN...AND INTO IOWA... ...SUMMARY... Severe thunderstorms are possible on Thursday from portions of the Upper/Middle Mississippi Valley to the central Plains. A few strong storms also will be possible over portions of the Virginia and North Carolina vicinity. ...Synopsis... While weak upper short-wave troughing shifts across the Northeast on Thursday, a much stronger trough/low will continue to advance into/across the north-central U.S. through the period. At the surface, a cold front is forecast to sag southward across the Mid-Atlantic region in lee of the Appalachians, while a more substantial cold front shifts eastward/southeastward across the Plains through the period. ...Mid and Upper Mississippi Valley area to the central Plains... As the upper low and associated trough extending southward across the northern Plains gradually advances, eastward progression of the associated cold front will result in afternoon storm development from western Minnesota southwestward into Kansas. While both instability and shear are expected to diminish gradually with southwestward extent along the front, 2500 to 3500 J/kg mixed-layer CAPE is forecast by late afternoon from central Minnesota into far northeastern Nebraska and Iowa, along with 0-6 km shear in the 35 to 45 kt range. This will support vigorous storms, and attendant risks for large hail and damaging wind gusts. With time, linear/upscale organization is expected to occur, with severe risk shifting across the Upper Midwest/upper Mississippi Valley region through the evening hours. Lesser risk with southwestward extent should gradually diminish after sunset. ...Virginia/North Carolina vicinity... As weak mid-level short-wave troughing shifts across the Northeast, a cold front back-dooring southward in lee of the Appalachians may focus development of afternoon showers and thunderstorms. Rather weak northwesterly flow aloft, but moderate destabilization that is expected to occur, will likely support a few multicell clusters, along with attendant risks for marginal hail and minor wind damage. Risk should remain confined to the afternoon and early evening hours, diminishing in tandem with nocturnal stabilization. ..Goss.. 08/28/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0104 AM CDT Wed Aug 28 2024 Valid 291200Z - 301200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF MINNESOTA AND WESTERN WISCONSIN...AND INTO IOWA... ...SUMMARY... Severe thunderstorms are possible on Thursday from portions of the Upper/Middle Mississippi Valley to the central Plains. A few strong storms also will be possible over portions of the Virginia and North Carolina vicinity. ...Synopsis... While weak upper short-wave troughing shifts across the Northeast on Thursday, a much stronger trough/low will continue to advance into/across the north-central U.S. through the period. At the surface, a cold front is forecast to sag southward across the Mid-Atlantic region in lee of the Appalachians, while a more substantial cold front shifts eastward/southeastward across the Plains through the period. ...Mid and Upper Mississippi Valley area to the central Plains... As the upper low and associated trough extending southward across the northern Plains gradually advances, eastward progression of the associated cold front will result in afternoon storm development from western Minnesota southwestward into Kansas. While both instability and shear are expected to diminish gradually with southwestward extent along the front, 2500 to 3500 J/kg mixed-layer CAPE is forecast by late afternoon from central Minnesota into far northeastern Nebraska and Iowa, along with 0-6 km shear in the 35 to 45 kt range. This will support vigorous storms, and attendant risks for large hail and damaging wind gusts. With time, linear/upscale organization is expected to occur, with severe risk shifting across the Upper Midwest/upper Mississippi Valley region through the evening hours. Lesser risk with southwestward extent should gradually diminish after sunset. ...Virginia/North Carolina vicinity... As weak mid-level short-wave troughing shifts across the Northeast, a cold front back-dooring southward in lee of the Appalachians may focus development of afternoon showers and thunderstorms. Rather weak northwesterly flow aloft, but moderate destabilization that is expected to occur, will likely support a few multicell clusters, along with attendant risks for marginal hail and minor wind damage. Risk should remain confined to the afternoon and early evening hours, diminishing in tandem with nocturnal stabilization. ..Goss.. 08/28/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1247 AM CDT Wed Aug 28 2024 Valid 281200Z - 291200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE OHIO VALLEY/MIDDLE ATLANTIC AND OVER THE DAKOTAS... ...SUMMARY... Severe thunderstorms are expected from the Ohio Valley to the northern Mid-Atlantic coast, and across parts of North and South Dakota. ...Ohio Valley/Middle Atlantic... Upper ridge is gradually breaking down over the Ohio Valley, as heights are suppressed along the southern fringe of stronger flow, in association with a progressive short-wave trough. Additionally, a weak disturbance is currently located over northern MO which should advance into Indiana by 18z. Aforementioned Great Lakes short-wave trough will encourage a surface boundary to sag south into the OH Valley by mid day. This boundary will likely serve as the primary focus for robust convective development later today. Early this morning, leading edge of a larger complex of convection has advanced into northwest OH. This activity will propagate downstream into western PA later this morning, and some intensification may occur along the leading edge of the MCS carcass as boundary-layer heating aids destabilization. If so, this activity would progress southeast toward MD/DE/southern NJ with an attendant risk for primarily wind. Upstream, a secondary corridor of robust convection should evolve ahead of the northern MO disturbance that tracks into IN by midday. Strongest corridor of instability will extend across southern IL into central OH ahead of this feature/surface front. While deep-layer flow will remain seasonally weak, damaging winds along with some hail risk will be noted with this robust convection. Convective temperatures will be breached early, and surface-based updrafts may begin to organize by 17-18z. ...Dakotas... Strong short-wave trough will migrate across the northern Rockies into eastern MT by 29/12z. 60-120m, 12hr mid-level height falls will develop ahead of this feature across eastern MT/western ND during the latter half of the period. This strong short wave will result in a pronounced surface front that will surge into the western Dakotas by 18z, then into the eastern Dakotas by the end of the period. Very strong surface heating is forecast across the High Plains of SD extending into extreme southern ND. This will result in a narrow corridor of strong buoyancy by early afternoon, but capping will hold until 22-23z as temperatures warm through the mid 90s. NAM forecast sounding for PIR at 23z exhibits negligible inhibition with ample 0-6km shear for supercells and very steep lapse rates. Models also suggest LLJ will strengthen ahead of the front, and this will support organized, longer-lived updrafts. Scattered supercells should evolve ahead of the front, and will pose a risk for very large hail and damaging winds. A tornado can not be ruled out with early evening supercells. ..Darrow/Squitieri.. 08/28/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1247 AM CDT Wed Aug 28 2024 Valid 281200Z - 291200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE OHIO VALLEY/MIDDLE ATLANTIC AND OVER THE DAKOTAS... ...SUMMARY... Severe thunderstorms are expected from the Ohio Valley to the northern Mid-Atlantic coast, and across parts of North and South Dakota. ...Ohio Valley/Middle Atlantic... Upper ridge is gradually breaking down over the Ohio Valley, as heights are suppressed along the southern fringe of stronger flow, in association with a progressive short-wave trough. Additionally, a weak disturbance is currently located over northern MO which should advance into Indiana by 18z. Aforementioned Great Lakes short-wave trough will encourage a surface boundary to sag south into the OH Valley by mid day. This boundary will likely serve as the primary focus for robust convective development later today. Early this morning, leading edge of a larger complex of convection has advanced into northwest OH. This activity will propagate downstream into western PA later this morning, and some intensification may occur along the leading edge of the MCS carcass as boundary-layer heating aids destabilization. If so, this activity would progress southeast toward MD/DE/southern NJ with an attendant risk for primarily wind. Upstream, a secondary corridor of robust convection should evolve ahead of the northern MO disturbance that tracks into IN by midday. Strongest corridor of instability will extend across southern IL into central OH ahead of this feature/surface front. While deep-layer flow will remain seasonally weak, damaging winds along with some hail risk will be noted with this robust convection. Convective temperatures will be breached early, and surface-based updrafts may begin to organize by 17-18z. ...Dakotas... Strong short-wave trough will migrate across the northern Rockies into eastern MT by 29/12z. 60-120m, 12hr mid-level height falls will develop ahead of this feature across eastern MT/western ND during the latter half of the period. This strong short wave will result in a pronounced surface front that will surge into the western Dakotas by 18z, then into the eastern Dakotas by the end of the period. Very strong surface heating is forecast across the High Plains of SD extending into extreme southern ND. This will result in a narrow corridor of strong buoyancy by early afternoon, but capping will hold until 22-23z as temperatures warm through the mid 90s. NAM forecast sounding for PIR at 23z exhibits negligible inhibition with ample 0-6km shear for supercells and very steep lapse rates. Models also suggest LLJ will strengthen ahead of the front, and this will support organized, longer-lived updrafts. Scattered supercells should evolve ahead of the front, and will pose a risk for very large hail and damaging winds. A tornado can not be ruled out with early evening supercells. ..Darrow/Squitieri.. 08/28/2024 Read more

MD 2022 CONCERNING SEVERE THUNDERSTORM WATCH 658...660... FOR NORTHERN IN...SOUTHWEST MI
Mesoscale Discussion 2022 NWS Storm Prediction Center Norman OK 0829 PM CDT Tue Aug 27 2024 Areas affected...Northern IN...southwest MI Concerning...Severe Thunderstorm Watch 658...660... Valid 280129Z - 280300Z The severe weather threat for Severe Thunderstorm Watch 658, 660 continues. SUMMARY...The damaging-wind threat is expected to spread southeastward with a small storm cluster. DISCUSSION...A small storm cluster that formed from initial supercell development near/north of Chicago has accelerated southeastward and become better organized this evening, with rather strong velocities (60-70 kt at 3-5 km ARL) noted from KLOT/KIWX radars. While MLCINH increases with southeastward extent, strong buoyancy and the current organized nature of this cluster will continue to support a threat of severe/damaging gusts across a larger part of northern IN and southwest MI into late evening. Isolated hail will also be possible with the strongest embedded updrafts within this cluster. ..Dean.. 08/28/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...IWX...LOT... LAT...LON 42068664 42008612 41908554 41708516 41418500 41128513 40928551 40938599 41088662 41338727 41638722 42068664 Read more

MD 2023 CONCERNING SEVERE THUNDERSTORM WATCH 658... FOR PARTS OF NORTHERN IL INTO EXTREME NORTHWEST IN
Mesoscale Discussion 2023 NWS Storm Prediction Center Norman OK 0939 PM CDT Tue Aug 27 2024 Areas affected...Parts of northern IL into extreme northwest IN Concerning...Severe Thunderstorm Watch 658... Valid 280239Z - 280415Z The severe weather threat for Severe Thunderstorm Watch 658 continues. SUMMARY...Some threat for hail and damaging wind may persist through late evening. DISCUSSION...Convection has largely become outflow dominant this evening across northern IL, within an environment that is strongly unstable (with MLCAPE of 3000-4000 J/kg), but with only weak to marginal deep-layer shear. Favorable thermodynamic profiles (as noted on the 00Z ILX/DVN soundings) will continue to support briefly intense updrafts with isolated hail potential. A large area of convective outflow has moved into western IL from northeast MO/southeast IA, with smaller outflows being generated by redeveloping storms within the primary instability axis. Locally damaging winds may accompany this outflow-dominant convection through late evening, before increasingly extensive convective overturning results in a weakening trend overnight. ..Dean.. 08/28/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LOT...ILX...DVN... LAT...LON 41079060 41458884 41528784 41558737 41418713 41118715 40818752 40538853 40428999 40439026 40509056 41079060 Read more

WW 0660 Status Updates
STATUS REPORT ON WW 660 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..DEAN..08/28/24 ATTN...WFO...IWX... STATUS REPORT FOR WS 660 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS INC017-039-049-069-085-087-091-099-103-113-131-141-149-169-181- 183-280340- IN . INDIANA COUNTIES INCLUDED ARE CASS ELKHART FULTON HUNTINGTON KOSCIUSKO LAGRANGE LA PORTE MARSHALL MIAMI NOBLE PULASKI ST. JOSEPH STARKE WABASH WHITE WHITLEY MIC021-027-149-280340- MI . MICHIGAN COUNTIES INCLUDED ARE BERRIEN CASS ST. JOSEPH THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more