SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1224 PM CDT Fri Aug 23 2024 Valid 241200Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE FOUR CORNERS REGION INTO THE CENTRAL HIGH PLAINS...AND OVER MAINLY WESTERN MISSOURI... ...SUMMARY... Marginally severe storms will be possible on Saturday across the Four Corners region eastward across the central High Plains. A small area of wind or small hail potential may also develop early over parts of western Missouri. ...Synopsis... On Saturday, a large upper trough will affect much of the West, with the primary vorticity max moving across the Great Basin. Southwest 500 mb winds in excess of 50 kt will overspread much of that area, extending into northern Rockies Meanwhile, an upper high will hold from the central and southern Plains to the mid MS Valley through Sunday morning. At the surface, a cold front will roughly stretch from central MT into central NV during the late afternoon, pushing east into the western Dakotas and southeast across UT and southern NV into Sunday morning. The better moisture and instability will be shunted east across far eastern UT and into CO, as low-level drying occurs over AZ and UT with persistent southwesterly winds. Farther east into the Plains, a plume of mid to upper 60s F dewpoints will develop northward across the MO Valley and toward the upper MS Valley late, aided by a heating/deepening boundary layer and around 30 kt southerly winds at 850 mb. This will also result an unstable air mass, with early-day thunderstorms expected over western MO and toward the mid MO Valley. ...Four Corners to the central High Plains... A fetch of midlevel moisture will remain over the area, which is also on the eastern fringe of the stronger flow aloft. Deep-layer effective shear will average 35-40 kt, a will conditionally favor scattered fast-moving cells. Storms are likely to form my early afternoon over far eastern UT into western CO, and extending southward across western NM. Sufficient shear and instability will favor marginal hail with the strongest cells, while favorable diurnal timing will and steep low-level lapse rates will be conducive for strong wind gusts. ...Parts of central and western MO early... Models are in good agreement with the development of a robust cluster of storms in the early-day warm advection regime centered over western MO. Given weak northwest flow aloft and a moistening low-level air mass, it is conceivable that any large cluster of storms could potentially forward-propagate southward across much of western MO. As such, low severe probabilities have been added. Shear will remain weak, but moderate instability may allow for very brief hail. ..Jewell.. 08/23/2024 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1158 AM CDT Fri Aug 23 2024 Valid 231700Z - 241200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE GREAT BASIN... The Isolated Dry Thunderstorm highlights were expanded into southwest Montana, where forecast soundings suggest the potential for fast-moving, high-based thunderstorms over modestly receptive fuels this afternoon. Some of these storms will be capable of producing severe wind gusts (around 60 mph), aided by enhanced deep-layer flow/shear and deep inverted-V thermodynamic profiles. For details on the severe-thunderstorm risk, see the SPC Day 1 Convective Outlook. Additionally, the Critical area in the Great Basin was expanded slightly eastward and southward, where the latest high-resolution guidance has increased confidence in the overlap of 20-30 mph sustained southerly surface winds and single-digit to lower-teens RH. Over portions of the southern Plains, very hot and dry conditions will develop this afternoon, which combined with breezy/gusty southerly surface winds, may promote locally elevated fire-weather conditions. There will also be some potential for an isolated lightning-induced ignition with thunderstorms over north-central TX. Overall, the fire-weather risk across this region appears too localized for highlights. ..Weinman.. 08/23/2024 .PREV DISCUSSION... /ISSUED 0144 AM CDT Fri Aug 23 2024/ ...Synopsis... A mid-level trough will enter portions of the Pacific Northwest, with enhanced mid-level flow overspreading portions of the Great Basin and vicinity. Afternoon heating/mixing will result in sustained surface winds of 20-25 mph while RH values drop into the teens, resulting in Elevated to Critical fire-weather conditions for this region. In addition, forcing for ascent associated with the aforementioned trough will allow for thunderstorms to develop across the Pacific Northwest, with a mix of wet and dry storms expected. Given dry/receptive fuels across the region, the area delineating isolated dry thunderstorm potential has been maintained. ...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 1127 AM CDT Fri Aug 23 2024 Valid 231630Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTHWEST/NORTH-CENTRAL MONTANA... ...SUMMARY... Strong to severe storms with severe wind gusts and some hail are possible across Montana, the Intermountain West and central Rockies, southeast Arizona to extreme southwestern New Mexico, and parts of the High Plains. ...Intermountain West to northern Rockies... The lead portion of an upper trough centered along the coastal Pacific Northwest will shift north-northeastward over the northern Intermountain region in tandem with the exit region of a strengthening mid/upper-level jet. Scattered thunderstorms are expected in this regime preceding the Pacific Coast trough, with initial development over the higher terrain ahead of the surface cold front. Isolated severe gusts and marginally severe hail will be possible, with the potential for a more focused corridor of stronger wind gusts across northwest/north-central Montana late this afternoon through early evening. Additional thunderstorms should form this afternoon across east/northeast Oregon, northern/eastern Idaho, to western Wyoming, and southeastward into Utah/western Colorado, as eastern fringes of large-scale ascent preceding the Pacific Northwest trough and embedded shortwaves overlie destabilizing, elevated terrain. Throughout the corridor, sufficient deep-layer shear (30-45 kt) should exist for organized multicells and small bowing/outflow-driven clusters, and perhaps a few supercells, with some hail and severe-caliber wind gusts possible. ...High Plains... Isolated to widely scattered thunderstorms are expected to form over the central/northern Rockies, as well as near the lee trough over eastern Montana this afternoon, with another favored corridor across the central High Plains including northeast Colorado/western Nebraska. Activity should move east-northeastward across the adjoining High Plains. This convection will encounter a diurnally destabilizing, well-mixed boundary layer with steep low-level lapse rates, supporting isolated severe wind gusts. Isolated large hail also will be possible. Strongly difluent mid/upper-level flow will exist over most of this corridor, between the Pacific Northwest cyclone and the southern Plains anticyclone, with speeds generally increasing northwestward and low-level moisture greater southward across the central High Plains. Still, sufficient moisture should persist near the Montana lee trough, along with enough veering with height over the entire area to yield enough deep shear (30+ kt effective-shear magnitudes) for organized convection. ...Southeast Arizona/far southwest New Mexico... Widely scattered to scattered thunderstorms are expected to develop this afternoon with a relatively moist air mass and ample insolation. Increasing mid-level southerlies around the western rim of the anticyclone should enable 20-30 kt effective-shear magnitudes, and enough northward storm motion to augment already strong downbursts from the most intense cells locally. An instance or two of marginally severe hail could also occur. ..Guyer/Wendt.. 08/23/2024 Read more

No Mesoscale Discussions are in effect as of Fri Aug 23 14:04:01 UTC 2024.

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Fri Aug 23 2024 Valid 231300Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS MONTANA...THE INTERMOUNTAIN WEST AND CENTRAL ROCKIES...SOUTHEAST ARIZONA TO EXTREME SOUTHWESTERN NEW MEXICO...AND THE CENTRAL AND NORTHERN HIGH PLAINS... ...SUMMARY... Strong to severe storms with severe gusts and possibly some hail are possible across Montana, the Intermountain West and central Rockies, southeast Arizona to extreme southwestern New Mexico, and the central and northern High Plains. ...Synopsis... A highly amplified but somewhat progressive mid/upper-level pattern is in place over the CONUS, led by a cyclone departing New England for the Canadian Maritimes. Weak mean troughing will persist in its wake over the Atlantic Coast States. A persistent anticyclone -- initially centered over southwestern OK -- should expand somewhat across the southern/central Plains while its 500-mb high drifts northeastward over OK through the period. West Coast troughing is anchored by a strong cyclone -- initially centered just off the OR Coast. This feature should shift eastward/inland through tonight, while breaking up into a couple strong shortwave troughs as internal vorticity maxima pivot over the Northwest and northern CA. A broad fetch of downstream southwest flow will extend across the Great Basin, Intermountain West, and northern/central Rockies. Moisture-channel imagery indicates embedded shortwave troughs over southeastern ID -- forecast to move northeastward over the northern Rockies today -- and over the Four Corners region. The latter perturbation should cross much of western/northern CO and southern WY today, reaching to WY/NE border vicinity by 00Z, then northeastward to eastern SD by 12Z. 11Z surface analysis showed a longstanding, quasistationary to warm frontal zone, from northern FL across the northeastern Gulf shelf waters to southern LA, north-central TX, southwestern OK, to a low over the northern TX Panhandle. This boundary still defines the northern rim of the richest Gulf moisture/theta-e, and should drift northward over the southern Plains through the period while moving little elsewhere. A low was drawn over eastern WA, with cold front across northeastern OR, central NV to south-central CA. This low should occlude and move northward into southern BC today, while the cold front moves slowly eastward across ID and northern NV, and loses definition farther south. A secondary low should form by 00Z over northwestern MT and move northeastward to the southern AB/SK border region by 12Z. Meanwhile, a lee trough will strengthen and extend from the secondary low southeastward over central/eastern MT, then over eastern arts of WY/CO. The trough should move northeastward over more of eastern MT, and into the western Dakotas, overnight. ...Intermountain West to northern Rockies... Scattered thunderstorms are expected in the field of southwesterly mid/upper flow, preceding the Pacific Coast trough, and mostly ahead of the surface cold front. Within that plume, isolated severe gusts and marginally severe hail will be possible. Severe potential may begin as early as midday to early afternoon -- and continue through the afternoon -- across parts of the eastern Great Basin/western Colorado Plateau region. This will occur as clearing behind the shortwave trough permits sustained heating of higher terrain from the Wasatch Range southward and southeastward. Additional thunderstorms should form this afternoon from western WY and eastern ID across western MT, as eastern fringes of large-scale ascent preceding the Pacific Northwest trough and embedded shortwaves overlie destabilizing, elevated terrain. A monsoonal plume and associated parallel moisture-transport vectors will ensure sufficient boundary-layer moisture supply, even through the diurnal heating/mixing process, with somewhat less moisture and deeper inverted-v thermodynamic profiles northward. MLCAPE should range from around 1000-2000 J/kg in southern UT, in richest moisture, to around 200-800 J/kg over the northern Rockies, in stronger flow aloft. Throughout the corridor, sufficient deep shear (30-45 kt) should exist for organized multicells, small bowing/ outflow-driven clusters, and perhaps a few supercells. Despite the weak moisture, enough is apparent to suggest isolated severe-gust potential into parts of eastern WA and northeastern OR, including areas of dry-thunder potential in the fire-weather outlook. ...Northern/central High Plains... Isolated to widely scattered thunderstorms are expected to form over the central/northern Rockies, as well as near the lee trough over eastern MT this afternoon. Activity should move northeastward to eastward across the adjoining High Plains. Along the way, this convection will encounter a diurnally destabilizing, well-mixed boundary layer with steep low-level lapse rates, supporting isolated severe gusts. Isolated large hail also will be possible. Strongly difluent mid/upper-level flow will exist over most of this corridor, between the Northwest cyclone and the southern Plains anticyclone, with speeds generally increasing northwestward and low-level moisture greater southward down the central High Plains. Still, sufficient moisture should persist near the MT lee trough, along with enough veering with height over the entire area to yield enough deep shear (30+ kt effective-shear magnitudes) for organized convection. Interestingly, most progs show a relative minimum in convective coverage in the area of greatest midlevel DCVA/ascent head of the ejecting shortwave trough, compared to farther north and south. For now, a long 5%/Marginal outlook will be maintained, with the understanding that conditional/localized concentrations of severe-gust potential in particular may exist where upscale aggregation can occur. Potential for activity to persist later into the evening is most apparent over the southern part of the outlook area, which has been expanded somewhat eastward accordingly. ...Southeastern AZ, extreme southwestern NM... Widely scattered to scattered thunderstorms are expected to develop this afternoon in a plume of monsoonal moisture and favorable surface heating today from western Chihuahua across southeastern AZ and southwestern NM, north-northeastward over eastern AZ and western NM. Increasing midlevel southerlies around the western rim of the anticyclone should enable 20-30 kt effective-shear magnitudes, and enough northward storm motion to augment already strong downbursts from the most intense cells locally. Isolated, marginally severe hail also may occur in some cores. Forecast soundings reasonably suggest that lower-elevation dewpoints, remaining in the 50s to near 60 F through most of the heating/mixing cycle, contribute to MLCAPE in the 1000-2000 J/kg range. ..Edwards/Bentley.. 08/23/2024 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0401 AM CDT Fri Aug 23 2024 Valid 261200Z - 311200Z ...DISCUSSION... Models continue to suggest potential for severe weather across parts of the Upper Mississippi Valley area Day4/Monday, as a mid-level short-wave trough is shunted northeastward across this region by the persistent central U.S. ridge. Timing of the advance of this feature differs between the GFS and ECMWF, casting some uncertainty, but enough agreement exists to maintain a 15% probability area across this region. One other area of interest Day 4/Monday is across portions of the southern New England/Mid-Atlantic vicinity within a northwesterly flow regime on the southwestern side of New England/Canadian Maritimes upper low. Enhanced northwesterlies aloft would be sufficient to produce rather fast-moving bands of storms, but degree of instability remains a substantial question at this time. With intensity of the convection thus still uncertain, will refrain at this time from introducing a risk area. As the north-central U.S. mid-level feature moves into/across Ontario Day 5, a decrease in severe risk is expected despite a weak frontal advance southeastward across the Great Lakes into the Ohio Valley. Beyond Day 5, models begin to deviate substantially, particularly with respect to their handling of the next trough expected to progress eastward across the Canadian Prairie and northwestern/north-central CONUS. While some severe potential could accompany this feature, particularly if an evolution that resembles the stronger ECMWF solution plays out, uncertainty precludes any reasonable assessment of severe potential. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0401 AM CDT Fri Aug 23 2024 Valid 261200Z - 311200Z ...DISCUSSION... Models continue to suggest potential for severe weather across parts of the Upper Mississippi Valley area Day4/Monday, as a mid-level short-wave trough is shunted northeastward across this region by the persistent central U.S. ridge. Timing of the advance of this feature differs between the GFS and ECMWF, casting some uncertainty, but enough agreement exists to maintain a 15% probability area across this region. One other area of interest Day 4/Monday is across portions of the southern New England/Mid-Atlantic vicinity within a northwesterly flow regime on the southwestern side of New England/Canadian Maritimes upper low. Enhanced northwesterlies aloft would be sufficient to produce rather fast-moving bands of storms, but degree of instability remains a substantial question at this time. With intensity of the convection thus still uncertain, will refrain at this time from introducing a risk area. As the north-central U.S. mid-level feature moves into/across Ontario Day 5, a decrease in severe risk is expected despite a weak frontal advance southeastward across the Great Lakes into the Ohio Valley. Beyond Day 5, models begin to deviate substantially, particularly with respect to their handling of the next trough expected to progress eastward across the Canadian Prairie and northwestern/north-central CONUS. While some severe potential could accompany this feature, particularly if an evolution that resembles the stronger ECMWF solution plays out, uncertainty precludes any reasonable assessment of severe potential. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0245 AM CDT Fri Aug 23 2024 Valid 251200Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE EASTERN DAKOTAS AND INTO NORTHERN MINNESOTA... ...SUMMARY... Severe weather risk is expected across the northern Plains area, and in a more isolated manner southwestward into the southern Rockies on Sunday. ...Synopsis... A persistent central U.S. upper ridge will be suppressed southward with time on Sunday, as a western U.S. trough shifts northeastward across the Intermountain West toward -- and eventually into -- the northern Plains/central High Plains area. At the surface, a cold front will accompany the upper system, shifting eastward into the northern/central Plains area, and southeastward across the southern Rockies. This front will focus convective development through the period. ...Northern Plains area southwestward into the southern Rockies... Daytime heating of a moist pre-frontal boundary layer will result in strong destabilization within an axis focused across the eastern Dakotas. While a low-level capping inversion should inhibit widespread convective development, isolated storms are forecast to initiate during the afternoon. As the upper trough advances, a lead belt of moderate -- 30 to 40 kt -- southwesterly flow is forecast atop the frontal zone. Resulting shear will support organized/rotating updrafts, and as such, attendant risks for large hail and damaging wind gusts. Farther southwestward along the front, a much less unstable airmass is anticipated -- into the central High Plains and southern Rockies. However, a deep mixed layer promoting potential for evaporatively driven downdraft acceleration, and the aforementioned/enhanced belt of southwesterlies at mid levels, suggest potential for damaging wind gusts with a few of the stronger storms/bands of storms which evolve during the afternoon and evening. ..Goss.. 08/23/2024 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0148 AM CDT Fri Aug 23 2024 Valid 241200Z - 251200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF NORTHERN/CENTRAL WYOMING... ...Synopsis... A mid-level trough over the Pacific Northwest will shift east and allow a belt of enhanced mid-level flow to overspread parts of the eastern Great Basin and the Northern Rockies. Afternoon heating/mixing will allow for sustained winds of 20-25 mph across the region while RH values fall into the upper teens and low 20s F. Fuels across portions far eastern Great Basin appear marginally receptive, and Elevated highlights have been maintained for this region, whereas fuels across parts of Wyoming appear more receptive where a Critical delineation has been added. In addition, potential for isolated dry thunderstorms has been introduced for the northern Great Basin in association with forcing from the advancing trough. Fuels in this region remain receptive to large-fire spread amid PWAT values that are projected to remain below 0.75 inches. ..Karstens.. 08/23/2024 ...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 0144 AM CDT Fri Aug 23 2024 Valid 231200Z - 241200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE GREAT BASIN... ...Synopsis... A mid-level trough will enter portions of the Pacific Northwest, with enhanced mid-level flow overspreading portions of the Great Basin and vicinity. Afternoon heating/mixing will result in sustained surface winds of 20-25 mph while RH values drop into the teens, resulting in Elevated to Critical fire-weather conditions for this region. In addition, forcing for ascent associated with the aforementioned trough will allow for thunderstorms to develop across the Pacific Northwest, with a mix of wet and dry storms expected. Given dry/receptive fuels across the region, the area delineating isolated dry thunderstorm potential has been maintained. ..Karstens.. 08/23/2024 ...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 0113 AM CDT Fri Aug 23 2024 Valid 241200Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE FOUR CORNERS REGION EASTWARD ACROSS THE CENTRAL HIGH PLAINS... ...SUMMARY... Marginally severe storms will be possible on Saturday across the Four Corners region eastward across the central High Plains. ...Synopsis... Large-scale upper ridging is forecast to prevail over the Plains Saturday, while a sharp trough advances slowly across the West. Meanwhile, weak troughing will prevail over the Northeast. At the surface, high pressure will prevail east of the Mississippi Valley, while a remnant baroclinic zone extends from the northern High Plains south-southeastward into the Kansas through most of the period. ...Four Corners area east-northeastward across the central High Plains... As upper troughing moves slowly eastward across the Intermountain West, modest destabilization across the Four Corners states will support isolated to scattered thunderstorm development. Though instability will remain weak, a belt of stronger mid-level flow on the eastern periphery of the aforementioned trough will allow a few stronger storms to evolve. This, combined with dry sub-cloud layer, suggests that locally damaging winds will be possible. By late afternoon and into the evening, storm development is forecast to increase across eastern Colorado and into the Nebraska Panhandle region -- in the vicinity of the surface boundary. While flow aloft will be weaker across this area, the strongest storms may produce damaging wind gusts and hail. Risk should diminish through late evening in tandem with nocturnal low-level stabilization. ..Goss.. 08/23/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0113 AM CDT Fri Aug 23 2024 Valid 241200Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE FOUR CORNERS REGION EASTWARD ACROSS THE CENTRAL HIGH PLAINS... ...SUMMARY... Marginally severe storms will be possible on Saturday across the Four Corners region eastward across the central High Plains. ...Synopsis... Large-scale upper ridging is forecast to prevail over the Plains Saturday, while a sharp trough advances slowly across the West. Meanwhile, weak troughing will prevail over the Northeast. At the surface, high pressure will prevail east of the Mississippi Valley, while a remnant baroclinic zone extends from the northern High Plains south-southeastward into the Kansas through most of the period. ...Four Corners area east-northeastward across the central High Plains... As upper troughing moves slowly eastward across the Intermountain West, modest destabilization across the Four Corners states will support isolated to scattered thunderstorm development. Though instability will remain weak, a belt of stronger mid-level flow on the eastern periphery of the aforementioned trough will allow a few stronger storms to evolve. This, combined with dry sub-cloud layer, suggests that locally damaging winds will be possible. By late afternoon and into the evening, storm development is forecast to increase across eastern Colorado and into the Nebraska Panhandle region -- in the vicinity of the surface boundary. While flow aloft will be weaker across this area, the strongest storms may produce damaging wind gusts and hail. Risk should diminish through late evening in tandem with nocturnal low-level stabilization. ..Goss.. 08/23/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Fri Aug 23 2024 Valid 231200Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF MT INTO THE INTERMOUNTAIN WEST/EASTERN GREAT BASIN...PARTS OF THE CENTRAL/NORTHERN HIGH PLAINS...AND SOUTHEAST AZ INTO EXTREME SOUTHWEST NM... ...SUMMARY... Strong to severe storms with severe gusts and possibly some hail are possible across Montana, the Intermountain West and central Rockies, southeast Arizona, and the central and northern High Plains. ...Synopsis... A seasonably deep mid/upper-level trough will persist over the West today. A strong embedded shortwave trough and attendant midlevel jet maximum will move quickly northeastward from the Great Basin into the interior Northwest/northern Rockies through the day. A surface low is forecast to deepen across western MT through the day, in conjunction with the passage of the shortwave trough. A weaker surface low may move gradually northeastward across the southern High Plains. Relatively rich low-level moisture will extend from TX/OK into the central/northern High Plains, while a plume of monsoonal moisture will persist from the Southwest/southern Rockies into eastern parts of the Great Basin. ...Parts of UT/western CO into the interior Northwest and western/central MT... Stronger ascent related to the ejecting shortwave trough over the interior Northwest may remain somewhat displaced from better moisture/instability through the day. However, it will likely aid in the development of scattered thunderstorms across a broad region from UT/western CO into parts of the Northwest/northern Rockies. The combination of relatively high-based convection and increasing low/midlevel flow will support a threat of at least isolated severe gusts across a broad region from the eastern Great Basin into parts of ID/MT. Steep lapse rates and sufficient deep-layer shear could also support an isolated hail threat, where sufficient pre-convective buoyancy can be realized. The Marginal Risk has been expanded across much of western/central MT, due to increased confidence in sufficiently deep convection to support a severe-wind threat. Portions of the Marginal Risk may eventually need greater wind probabilities, if confidence increases in one or more corridors where a greater coverage of severe gusts will be possible. Some severe-wind threat could also evolve west of the current Marginal across parts of OR/WA/western ID, in closer proximity to the shortwave trough, but confidence is lower at this time due to very limited forecast buoyancy in this area. ...Parts of the High Plains... Moderate to locally strong buoyancy is forecast to develop this afternoon across much of the High Plains, along/east of a wavy surface trough extending between the surface lows across MT and the southern High Plains. However, large-scale ascent will likely remain rather nebulous across this region, and the details of storm development and coverage remain uncertain. While midlevel flow will be somewhat weaker compared to areas farther west, it will remain sufficient to support effective shear of 30+ kt, conditionally supporting organized convection. Any sustained storms that can develop and be maintained during the afternoon/evening would pose a threat of isolated hail and severe gusts. ...Southeast AZ vicinity... Scattered thunderstorms are again expected across southeast AZ into adjacent southwest NM. A modest increase in midlevel flow could support somewhat more organized storms compared to Thursday. Moderate buoyancy and effective shear increasing into the 20-25 kt range will support a threat of localized strong/severe gusts and possibly some hail with the strongest storms. ..Dean.. 08/23/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Fri Aug 23 2024 Valid 231200Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF MT INTO THE INTERMOUNTAIN WEST/EASTERN GREAT BASIN...PARTS OF THE CENTRAL/NORTHERN HIGH PLAINS...AND SOUTHEAST AZ INTO EXTREME SOUTHWEST NM... ...SUMMARY... Strong to severe storms with severe gusts and possibly some hail are possible across Montana, the Intermountain West and central Rockies, southeast Arizona, and the central and northern High Plains. ...Synopsis... A seasonably deep mid/upper-level trough will persist over the West today. A strong embedded shortwave trough and attendant midlevel jet maximum will move quickly northeastward from the Great Basin into the interior Northwest/northern Rockies through the day. A surface low is forecast to deepen across western MT through the day, in conjunction with the passage of the shortwave trough. A weaker surface low may move gradually northeastward across the southern High Plains. Relatively rich low-level moisture will extend from TX/OK into the central/northern High Plains, while a plume of monsoonal moisture will persist from the Southwest/southern Rockies into eastern parts of the Great Basin. ...Parts of UT/western CO into the interior Northwest and western/central MT... Stronger ascent related to the ejecting shortwave trough over the interior Northwest may remain somewhat displaced from better moisture/instability through the day. However, it will likely aid in the development of scattered thunderstorms across a broad region from UT/western CO into parts of the Northwest/northern Rockies. The combination of relatively high-based convection and increasing low/midlevel flow will support a threat of at least isolated severe gusts across a broad region from the eastern Great Basin into parts of ID/MT. Steep lapse rates and sufficient deep-layer shear could also support an isolated hail threat, where sufficient pre-convective buoyancy can be realized. The Marginal Risk has been expanded across much of western/central MT, due to increased confidence in sufficiently deep convection to support a severe-wind threat. Portions of the Marginal Risk may eventually need greater wind probabilities, if confidence increases in one or more corridors where a greater coverage of severe gusts will be possible. Some severe-wind threat could also evolve west of the current Marginal across parts of OR/WA/western ID, in closer proximity to the shortwave trough, but confidence is lower at this time due to very limited forecast buoyancy in this area. ...Parts of the High Plains... Moderate to locally strong buoyancy is forecast to develop this afternoon across much of the High Plains, along/east of a wavy surface trough extending between the surface lows across MT and the southern High Plains. However, large-scale ascent will likely remain rather nebulous across this region, and the details of storm development and coverage remain uncertain. While midlevel flow will be somewhat weaker compared to areas farther west, it will remain sufficient to support effective shear of 30+ kt, conditionally supporting organized convection. Any sustained storms that can develop and be maintained during the afternoon/evening would pose a threat of isolated hail and severe gusts. ...Southeast AZ vicinity... Scattered thunderstorms are again expected across southeast AZ into adjacent southwest NM. A modest increase in midlevel flow could support somewhat more organized storms compared to Thursday. Moderate buoyancy and effective shear increasing into the 20-25 kt range will support a threat of localized strong/severe gusts and possibly some hail with the strongest storms. ..Dean.. 08/23/2024 Read more

MD 1975 CONCERNING SEVERE THUNDERSTORM WATCH 644... FOR CENTRAL HIGH PLAINS
Mesoscale Discussion 1975 NWS Storm Prediction Center Norman OK 0844 PM CDT Thu Aug 22 2024 Areas affected...Central High Plains Concerning...Severe Thunderstorm Watch 644... Valid 230144Z - 230345Z The severe weather threat for Severe Thunderstorm Watch 644 continues. SUMMARY...Wind/hail threat will spread across eastern portions of ww644 over the next several hours. DISCUSSION...Scattered high-based convection that initiated over the higher terrain of central/southern CO has matured into an MCS that is now advancing into northwest KS. Over the last hour or so, a weak MCV appears to have developed which is now just south of AKO, supporting the overall organization of this complex. 1km AGL southeasterly inflow across western KS is on the order of 25-30kt, which will encourage propagation across at least the western portions of the main instability corridor. 00z soundings from the central High Plains exhibit substantial CINH, and further boundary-layer stabilization is expected as surface temperatures cool. Given the organization of this complex, further propagation is likely into the eastern-most portions of the watch; however, updraft intensities have likely peaked and gradual weakening can be expected by 03-04z. Until then, damaging winds will likely be the primary risk. ..Darrow.. 08/23/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...GLD...PUB...BOU... LAT...LON 40200372 40500082 38750082 38450370 40200372 Read more

WW 0644 Status Updates
STATUS REPORT ON WW 644 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 45 SSE ITR TO 10 ESE ITR TO 20 NNW ITR TO 25 SSE AKO TO 25 W AKO. ..SPC..08/23/24 ATTN...WFO...GLD...BOU... STATUS REPORT FOR WS 644 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS COC121-125-230240- CO . COLORADO COUNTIES INCLUDED ARE WASHINGTON YUMA KSC023-071-109-153-181-193-199-203-230240- KS . KANSAS COUNTIES INCLUDED ARE CHEYENNE GREELEY LOGAN RAWLINS SHERMAN THOMAS WALLACE WICHITA NEC057-087-230240- NE . NEBRASKA COUNTIES INCLUDED ARE DUNDY HITCHCOCK Read more

WW 644 SEVERE TSTM CO KS NE 222325Z - 230500Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 644 NWS Storm Prediction Center Norman OK 525 PM MDT Thu Aug 22 2024 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Eastern Colorado Western Kansas Far Southwest Nebraska * Effective this Thursday afternoon and evening from 525 PM until 1100 PM MDT. * Primary threats include... Scattered damaging winds and isolated significant gusts to 75 mph possible Isolated very large hail events to 2 inches in diameter possible SUMMARY...Thunderstorms should continue to congeal into a cluster this evening while moving eastward across eastern Colorado into western Kansas, with mainly a threat for scattered severe/damaging winds around 60-70 mph. Isolated gusts up to 75 mph appear possible, along with occasional large hail around 1-1.75 inches in diameter. The severe thunderstorm watch area is approximately along and 60 statute miles north and south of a line from 5 miles north northwest of Limon CO to 50 miles east northeast of Goodland KS. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU4). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && AVIATION...A few severe thunderstorms with hail surface and aloft to 2 inches. Extreme turbulence and surface wind gusts to 65 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 25025. ...Gleason Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0800 PM CDT Thu Aug 22 2024 Valid 230100Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... Storms capable of producing severe wind gusts and isolated hail remain possible over parts of the central High Plains this evening. ...Central High Plains... Storms have intensified early this evening across eastern CO, with several measured severe gusts (including 68 kt at Lamar, CO), and large hail reported west of Goodland near the CO/KS border. Moderate to locally strong buoyancy and sufficient deep-layer shear will continue to support organized convection through the evening. Isolated supercells with a short-term threat of hail, severe gusts, and possibly a brief tornado will continue to be possible in the vicinity of a stationary surface boundary across northwest KS. A continued tendency toward one or more outflow-driven clusters is expected with time, with a threat of 60-80 mph wind gusts spreading across parts of western KS. An eventual weakening trend is expected with time later tonight, as MLCINH increases with time and eastward extent. ..Dean.. 08/23/2024 Read more

MD 1974 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR CENTRAL HIGH PLAINS
Mesoscale Discussion 1974 NWS Storm Prediction Center Norman OK 0551 PM CDT Thu Aug 22 2024 Areas affected...Central High Plains Concerning...Severe potential...Watch possible Valid 222251Z - 230045Z Probability of Watch Issuance...60 percent SUMMARY...Convection is expected to increase in areal coverage across the central High Plains over the next few hours. Hail/wind are possible with these storms as they spread across eastern Colorado toward northwest Kansas. DISCUSSION...Strong surface heating has contributed to very steep 0-3km lapse rates across eastern Colorado. Scattered robust convection has developed off the higher terrain which is now propagating over lower elevations where temperatures remain in the 90s. Over the next few hours, this activity will spread into a corridor of somewhat stronger low-level convergence characterized by higher boundary-layer moisture and stronger instability. Diagnostic data suggests MLCAPE values are near 2000 J/kg near the CO/KS border where surface dew points are holding above 60F. While satellite imagery does not explicitly reflect any short-wave troughs, modest 500mb southwesterly flow does extend across this region and 0-6km bulk shear is at least 30kt. This environment is supportive of supercells and ongoing activity should continue to grow upscale into the early evening. With time, LLJ is forecast to increase across the TX Panhandle into western KS so a larger complex of storms could emerge. Hail/wind are the primary threats. ..Darrow/Gleason.. 08/22/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DDC...GLD...PUB...BOU... LAT...LON 39290438 40480325 39570110 37690229 39290438 Read more

WW 0644 Status Updates
STATUS FOR WATCH 0644 HAS NOT BEEN ISSUED YET Read more