WW 676 SEVERE TSTM KS 180005Z - 180400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 676 NWS Storm Prediction Center Norman OK 705 PM CDT Tue Sep 17 2024 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Southwest Kansas * Effective this Tuesday evening from 705 PM until 1100 PM CDT. * Primary threats include... Scattered damaging winds and isolated significant gusts to 75 mph possible SUMMARY...A line of high-based thunderstorms will spread into southwest Kansas through the evening, posing a risk of locally damaging wind gusts. The severe thunderstorm watch area is approximately along and 35 statute miles east and west of a line from 55 miles north northwest of Garden City KS to 20 miles west southwest of Liberal KS. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU6). 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. && OTHER WATCH INFORMATION...CONTINUE...WW 674...WW 675... AVIATION...A few severe thunderstorms with hail surface and aloft to 1 inch. Extreme turbulence and surface wind gusts to 65 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 24035. ...Hart Read more

WW 0674 Status Updates
STATUS REPORT ON WW 674 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..SPC..09/17/24 ATTN...WFO...PUB...ABQ... STATUS REPORT FOR WS 674 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS COC003-009-011-021-023-025-027-041-043-055-061-071-089-099-101- 109-119-172240- CO . COLORADO COUNTIES INCLUDED ARE ALAMOSA BACA BENT CONEJOS COSTILLA CROWLEY CUSTER EL PASO FREMONT HUERFANO KIOWA LAS ANIMAS OTERO PROWERS PUEBLO SAGUACHE TELLER NMC005-007-009-011-019-021-027-033-037-041-047-055-059-172240- NM . NEW MEXICO COUNTIES INCLUDED ARE CHAVES COLFAX CURRY DE BACA GUADALUPE HARDING LINCOLN MORA QUAY ROOSEVELT SAN MIGUEL TAOS UNION Read more

MD 2080 CONCERNING SEVERE THUNDERSTORM WATCH 674... FOR SOUTHEAST COLORADO INTO EASTERN NEW MEXICO
Mesoscale Discussion 2080 NWS Storm Prediction Center Norman OK 0404 PM CDT Tue Sep 17 2024 Areas affected...Southeast Colorado into eastern New Mexico Concerning...Severe Thunderstorm Watch 674... Valid 172104Z - 172300Z The severe weather threat for Severe Thunderstorm Watch 674 continues. SUMMARY...The severe threat continues across WW 674 with an increasing wind threat emerging across southeast Colorado and predominantly a hail threat across east/northeast New Mexico. DISCUSSION...Large scale ascent associated with the main upper wave continues to overspread the central Rockies with an uptick in convection noted across south-central CO over the past half hour. A combination of orographic ascent and deep-layer shear oriented along the terrain/initiation zone have favored a linear storm mode with pockets of enhanced low-level velocity noted from the KPUX radar. Downstream from this developing line, MLCAPE continues to increase to around 1000 J/kg in conjunction with strengthening deep-layer shear as the mid-level jet overspreads the region. Consequently, further intensification of this line appears probable with a corresponding increase in severe wind potential downstream across southeast/east-central CO. Further south across eastern NM, more discrete storm mode has supported a few supercells with notable MRMS hail signatures. Weaker forcing for ascent and 30-45 knots of effective bulk shear should continue to favor discrete/semi-discrete cells with a continued risk for large hail for the next few hours. The eastward extent of the risk remains somewhat nebulous as buoyancy decreases into the TX Panhandle due to somewhat shallower mid-level lapse rates; however, convective trends will continue to be monitored. ..Moore.. 09/17/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GLD...AMA...PUB...BOU...ABQ... LAT...LON 37900229 36100294 34800325 34230345 33850386 33670417 33600450 33600470 33730486 34010508 34220519 34550521 35660506 36580479 37480471 38120491 38430499 38710490 39550247 39370203 38990185 38500198 37900229 Read more

WW 0675 Status Updates
STATUS REPORT ON WW 675 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..SPC..09/17/24 ATTN...WFO...BOU...GLD...LBF...CYS... STATUS REPORT FOR WS 675 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS COC001-005-017-039-063-073-075-087-095-115-121-123-125-172240- CO . COLORADO COUNTIES INCLUDED ARE ADAMS ARAPAHOE CHEYENNE ELBERT KIT CARSON LINCOLN LOGAN MORGAN PHILLIPS SEDGWICK WASHINGTON WELD YUMA KSC023-071-109-153-181-193-199-203-172240- KS . KANSAS COUNTIES INCLUDED ARE CHEYENNE GREELEY LOGAN RAWLINS SHERMAN THOMAS WALLACE WICHITA NEC005-007-013-029-033-045-049-057-069-075-085-087-091-101-105- 111-117-123-135-157-161-165-172240- NE Read more

WW 675 SEVERE TSTM CO KS NE WY 172055Z - 180300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 675 NWS Storm Prediction Center Norman OK 255 PM MDT Tue Sep 17 2024 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Northeast and East-Central Colorado Northwest Kansas Western Nebraska Eastern Wyoming * Effective this Tuesday afternoon and evening from 255 PM until 900 PM MDT. * Primary threats include... Widespread damaging winds likely with isolated significant gusts to 80 mph possible Isolated large hail events to 1 inch in diameter possible SUMMARY...High-based convection should gradually increase in coverage and intensity as it spreads northeastward across the central High Plains this afternoon and evening. Numerous strong to severe wind gusts should be the main threat with this activity, with the highest gusts potentially reaching up to 70-80 mph. The severe thunderstorm watch area is approximately along and 80 statute miles east and west of a line from 35 miles south southwest of Burlington CO to 60 miles north northeast of Torrington WY. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU5). 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. && OTHER WATCH INFORMATION...CONTINUE...WW 674... AVIATION...A few severe thunderstorms with hail surface and aloft to 1 inch. Extreme turbulence and surface wind gusts to 70 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 24040. ...Gleason Read more

WW 0674 Status Updates
STATUS REPORT ON WW 674 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..SPC..09/17/24 ATTN...WFO...PUB...ABQ... STATUS REPORT FOR WS 674 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS COC003-009-011-021-023-025-027-041-043-055-061-071-089-099-101- 109-119-172240- CO . COLORADO COUNTIES INCLUDED ARE ALAMOSA BACA BENT CONEJOS COSTILLA CROWLEY CUSTER EL PASO FREMONT HUERFANO KIOWA LAS ANIMAS OTERO PROWERS PUEBLO SAGUACHE TELLER NMC005-007-009-011-019-021-027-033-037-041-047-055-059-172240- NM . NEW MEXICO COUNTIES INCLUDED ARE CHAVES COLFAX CURRY DE BACA GUADALUPE HARDING LINCOLN MORA QUAY ROOSEVELT SAN MIGUEL TAOS UNION Read more

WW 674 SEVERE TSTM CO NM 171845Z - 180100Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 674 NWS Storm Prediction Center Norman OK 1245 PM MDT Tue Sep 17 2024 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of South-Central and Southeast Colorado Eastern New Mexico * Effective this Tuesday afternoon and evening from 1245 PM until 700 PM MDT. * Primary threats include... Scattered damaging winds likely with isolated significant gusts to 75 mph possible Isolated large hail events to 1.5 inches in diameter possible SUMMARY...Thunderstorms that have developed over the higher terrain of the southern/central Rockies will continue to move quickly east-northeastward this afternoon and early evening. They should also intensify over the next several hours while posing a threat for mainly severe damaging winds up to 65-75 mph. Isolated large hail around 1-1.5 inches in diameter may also occur. The severe thunderstorm watch area is approximately along and 60 statute miles east and west of a line from 35 miles east northeast of Pueblo CO to 5 miles southwest of Roswell NM. 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 1.5 inches. Extreme turbulence and surface wind gusts to 65 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 24040. ...Gleason Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0411 PM CDT Tue Sep 17 2024 Valid 191200Z - 251200Z An active mid-level flow regime is expected across the CONUS over the next seven days. A mid-level trough and speed max will pass through the southern Rockies and Plains late this week and into the weekend. A strong lee cyclone will support gusty winds and low humidity. However, widespread rainfall is also expected. Behind the trough, high pressure and higher-latitude zonal flow will develop over the Northwest early next week. Some potential for easterly offshore could develop, but significant forecast uncertainty is present in the medium range. This suggests the threat for fire-weather conditions is relatively low. ...Southern Plains... As the aforementioned trough ejects eastward, strong southwesterly flow aloft will overspread much of the southern Rockies and High Plains. Currently, area fuels are not receptive to fire spread. Additional precipitation also appears likely over the next few days. However, strong lee cyclogenesis is also expected to bolster surface winds (20-25 mph) over much of the Plains through the end of the week and into the early weekend. Some potential for drying mid week could support at least some low-end fire-weather concerns if fuels are able to dry. While this is uncertain, some risk for fire-weather concerns is possible. ...West Coast... Late in the weekend and into early next week, some model guidance shows the development of high pressure across the Great Basin, while broad weak troughing could intensify off the West Coast. Should this occur, offshore pressure gradients may develop, and could support some dry and breezy conditions across parts of CA and the coastal ranges of WA and OR. However, forecast and fuels uncertainty is significant, and no probabilities will be introduced until a clearer solution develops. ..Lyons.. 09/17/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0411 PM CDT Tue Sep 17 2024 Valid 191200Z - 251200Z An active mid-level flow regime is expected across the CONUS over the next seven days. A mid-level trough and speed max will pass through the southern Rockies and Plains late this week and into the weekend. A strong lee cyclone will support gusty winds and low humidity. However, widespread rainfall is also expected. Behind the trough, high pressure and higher-latitude zonal flow will develop over the Northwest early next week. Some potential for easterly offshore could develop, but significant forecast uncertainty is present in the medium range. This suggests the threat for fire-weather conditions is relatively low. ...Southern Plains... As the aforementioned trough ejects eastward, strong southwesterly flow aloft will overspread much of the southern Rockies and High Plains. Currently, area fuels are not receptive to fire spread. Additional precipitation also appears likely over the next few days. However, strong lee cyclogenesis is also expected to bolster surface winds (20-25 mph) over much of the Plains through the end of the week and into the early weekend. Some potential for drying mid week could support at least some low-end fire-weather concerns if fuels are able to dry. While this is uncertain, some risk for fire-weather concerns is possible. ...West Coast... Late in the weekend and into early next week, some model guidance shows the development of high pressure across the Great Basin, while broad weak troughing could intensify off the West Coast. Should this occur, offshore pressure gradients may develop, and could support some dry and breezy conditions across parts of CA and the coastal ranges of WA and OR. However, forecast and fuels uncertainty is significant, and no probabilities will be introduced until a clearer solution develops. ..Lyons.. 09/17/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Tue Sep 17 2024 Valid 172000Z - 181200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... Thunderstorms capable of producing scattered to numerous severe wind gusts and isolated large hail should occur this afternoon and evening across much of the High Plains. Some of the wind gusts may be significant (75+ mph). ...20Z Update... Relatively minor adjustments were made to the wind probabilities across parts of the southern Rockies/High Plains where convection has increased and shown some signs of linear organization. A significant wind gust or two is possible as this activity tracks north-northeastward into better moisture. The remainder of the forecast remains on track and is unchanged. ..Wendt.. 09/17/2024 .PREV DISCUSSION... /ISSUED 1126 AM CDT Tue Sep 17 2024/ ...High Plains and Central/Southern Rockies... Expansions have been made to the Slight and Enhanced Risks across the northern/central High Plains to account for latest trends in guidance and observations. The Marginal Risk has also been expanded westward to include more of western CO and western/central WY, where isolated strong to severe winds are already ongoing with high-based convection. A strong upper trough/low over the Great Basin will pivot east-northeastward across the northern/central Rockies through this evening. An associated 50-60 kt mid-level jet will move eastward across the central/southern Rockies this afternoon, and over parts of the adjacent High Plains through this evening. As large-scale ascent with the upper trough and mid-level jet overspreads these regions, a surface low is forecast to deepen over eastern MT through this evening, while another low also develops over the central High Plains. A surface trough will extend southward from the central High Plains low, and it should sharpen as it develops eastward across the central/southern High Plains through the day. Greater low-level moisture, characterized by generally mid 50s to low 60s surface dewpoints, will gradually increase today along/east of the surface trough, while remaining more limited across the higher terrain of the central/southern Rockies. Moderate instability should develop to the east of the surface trough across much of the High Plains through peak afternoon heating. Strengthening deep-layer shear with the approach of the mid-level jet will support organized convection, including some potential for initial supercells across the northern High Plains (eastern MT and vicinity). Related threat for large hail will exist with any of this more discrete convection. Otherwise, thunderstorms will continue to develop this afternoon over the central/southern Rockies while producing isolated strong to severe wind gusts in a weakly unstable but strongly sheared environment. This activity will eventually spread off the higher terrain and into the central/southern High Plains. Steepened low-level lapse rates with robust daytime heating, along with more limited/shallow low-level moisture along/west of the surface trough, will likely support a gradually increasing severe wind threat with the high-based convection spreading east-northeastward across the southern/central Rockies. As these clusters and linear segments encounter greater low-level moisture and related instability along/east of the surface trough across the High Plains late this afternoon into early evening, the threat for scattered to numerous severe wind gusts should increase. This may particularly be the case across parts of the central High Plains, where the best combination of steepened low-level lapse rates, moderate instability, moderate to strong deep-layer shear, and greatest linear convective signal exists in 12Z guidance. Some chance for isolated gusts of 75+ mph may also be realized across this region with the more intense clusters spreading east-northeastward in tandem with the mid-level jet. The threat for severe winds is expected to gradually decrease with eastward extent across the Plains this evening as convection encounters increasing MLCIN with nocturnal cooling of the boundary layer. ...Florida... A weak mid/upper-level low will remain centered over the Southeast today. Modest mid-level westerly flow will persist over FL on the southern periphery of the upper low. Scattered to numerous thunderstorms should develop later this afternoon along/south of a remnant front, and along the Atlantic Coast sea breeze. Even with daytime heating of a rather moist low-level airmass, poor mid-level lapse rates should temper updraft intensities to some extent, even as moderate instability develops. That said, the stronger cores may be capable of producing isolated strong to damaging winds, with 20-25 kt of deep-layer shear aiding in modest thunderstorm organization. Some adjustments have been made to the Marginal Risk across parts of the FL Peninsula, based on latest observational trends and 12Z guidance. ...Southeast Virginia/Northeast North Carolina... A weak convective band is ongoing across far northeast NC into southeast VA, on the northeast side of a mid/upper-level low over the Southeast. Occasional strong/gusty winds may occur with the more robust cores this afternoon as the convective band pivots further into southeast VA. Even so, weak instability, modest low/mid-level flow, and related weak shear should temper overall thunderstorm organization. Accordingly, severe wind potential should remain low. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0242 PM CDT Tue Sep 17 2024 Valid 181200Z - 191200Z ...NO CRITICAL AREAS... ...20z Update... Model and observational trends continue to suggest widespread wetting rainfall is likely over much of the central and northern High Plains late D1/Tuesday into early D2/Wednesday. Thus, despite strong winds and pockets of lower humidity, the availability of dry fuels appears limited. See the previous discussion for more details. ..Lyons.. 09/17/2024 .PREV DISCUSSION... /ISSUED 0156 AM CDT Tue Sep 17 2024/ ...Synopsis... Strong deep-layer southwesterly flow will overspread the Dakotas, within the base of a negatively tilted midlevel trough/low moving northeastward across the northern High Plains. A tight pressure gradient peripheral to a related surface cyclone over eastern MT will promote strong post-frontal surface winds across western SD. While these winds and around 20 percent RH would typically warrant fire-weather highlights, substantial precipitation over the past week, and additional expected rainfall on Day 1/Tuesday, limit confidence in fuel receptiveness. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 2078 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR SOUTHEAST COLORADO INTO EASTERN NEW MEXICO
Mesoscale Discussion 2078 NWS Storm Prediction Center Norman OK 0125 PM CDT Tue Sep 17 2024 Areas affected...Southeast Colorado into eastern New Mexico Concerning...Severe potential...Watch likely Valid 171825Z - 172030Z Probability of Watch Issuance...80 percent SUMMARY...Thunderstorms developing across central to northern New Mexico are expected to increase in coverage and intensity through the afternoon hours. Trends are being monitored, and watch issuance is anticipated soon. DISCUSSION...Over the past 30-60 minutes, initially weak convection across central to northern NM has shown signs of steady intensification via increased lightning activity and steadily cooling cloud-top temperatures. This uptick is largely being driven by diurnal destabilization as temperatures warm into the low to mid 80s, which is eroding MLCIN and bolstering MLCAPE to around 1000 J/kg across northern NM. Further intensification downstream across northeast/eastern NM and southeast CO appears likely as storms migrate into a relatively more moist/buoyant environment where southerly low-level winds are maintaining dewpoints in the upper 50s to low 60s. 30-40 knot mid-level flow should spread east in tandem with the deepening convection, which should provide adequate deep-layer shear for organized convection. Based on recent radar trends, a mix of semi-discrete clusters and supercells appears likely with an attendant risk of large hail (most likely between 1.0 to 1.5 inches in diameter) and strong to severe winds. Watch issuance will likely be needed soon as convection continues to intensify and poses a greater severe threat. ..Moore/Gleason.. 09/17/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...AMA...PUB...ABQ... LAT...LON 33400537 34760565 35270600 35800617 36550610 37160577 37590516 37890430 38000351 37650305 36910283 36010290 35080304 34410318 33980341 33580373 33310498 33400537 Read more

MD 2079 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR EASTERN WYOMING...NORTHEASTERN/EAST CENTRAL COLORADO...ADJACENT SOUTHWESTERN SOUTH DAKOTA AND WESTERN NEBRASKA
Mesoscale Discussion 2079 NWS Storm Prediction Center Norman OK 0208 PM CDT Tue Sep 17 2024 Areas affected...eastern Wyoming...northeastern/east central Colorado...adjacent southwestern South Dakota and western Nebraska Concerning...Severe potential...Watch possible Valid 171908Z - 172145Z Probability of Watch Issuance...60 percent SUMMARY...High-based thunderstorm development appears increasingly probable across and east of the Front Range by 3-5 PM MDT, accompanied by increasing potential for strong to severe wind gusts while spreading through the adjacent high plains through early evening. One or two severe weather watches are possible, though timing remains somewhat uncertain. DISCUSSION...Downstream of a vigorous short wave trough pivoting northeastward toward the Wyoming/Colorado Rockies, southwesterly mid/upper flow is in the process of strengthening. This is forecast to include speeds of 40-70+ kt in the 500-300 mb layer across and northeast of the Front Range, above a boundary layer across the high plains which is becoming strongly heated and deeply mixed. Surface temperature/dew points already have commonly reached 40-45 degrees across much of eastern Colorado and Wyoming. While boundary-layer moisture content is generally low, various model output indicates that steepening lower/mid-tropospheric lapse rates, along the leading edge of mid-level cooling now approaching the Front Range, will support increasing high-based convective development along and east of the higher terrain by 20-22Z. Updrafts might not be particularly intense, at least initially as activity begins to spread toward the high plains, but sub-cloud evaporative cooling and downward mixing of cloud-bearing mean flow on the order of 50 kt are likely to contribute to the risk for strong to severe downbursts. Thereafter, the potential for strong to severe wind gusts may gradually become more widespread as convective outflow becomes more widespread and strengthens while surging northeastward and eastward. ..Kerr/Gleason.. 09/17/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...UNR...GLD...PUB...BOU...CYS... LAT...LON 43860453 43310377 42380364 41490341 39840284 38860290 38430401 39050489 40020512 41470531 42270551 43080550 43860453 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0152 PM CDT Tue Sep 17 2024 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE UPPER MIDWEST... ...SUMMARY... Scattered severe thunderstorms are possible from mid-afternoon to early evening on Thursday across central to eastern Minnesota and north-central Iowa. ...Upper Midwest... Minor adjustments (mainly eastward expansion) to severe probabilities have been made based on latest forecast guidance for the Day 3/Thursday period, but overall forecast philosophy remains unchanged from the previous outlook. A negatively tilted upper shortwave trough will shift east/northeast from the northern Plains/Canadian Prairies toward the Upper Midwest and western Ontario. Mid/upper west/southwesterly flow will remain somewhat enhanced (around 30-40 kt 850-700 mb flow) through around 00z before the system as a whole weakens. At the surface, a cold front will extend roughly north to south/southwest from western MN into southeast NE at midday. Ahead of this feature, southerly low-level flow will maintain 60s F dewpoints across IA into eastern MN/western WI. The warm sector will remain rather narrow due to generally high pressure and a drier boundary layer over much of the Midwest east of the MS River. Nevertheless, within the axis of greater moisture/low-level theta-e, around 1000-2000 J/kg MLCAPE is forecast. Organized thunderstorm clusters and line segments will pose a risk of isolated severe gusts and hail through early evening. The severe risk should rapidly diminish beyond 00z with loss of daytime heating, limited moisture/instability with eastward extent, and weakening deep-layer flow. ..Leitman.. 09/17/2024 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0152 PM CDT Tue Sep 17 2024 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE UPPER MIDWEST... ...SUMMARY... Scattered severe thunderstorms are possible from mid-afternoon to early evening on Thursday across central to eastern Minnesota and north-central Iowa. ...Upper Midwest... Minor adjustments (mainly eastward expansion) to severe probabilities have been made based on latest forecast guidance for the Day 3/Thursday period, but overall forecast philosophy remains unchanged from the previous outlook. A negatively tilted upper shortwave trough will shift east/northeast from the northern Plains/Canadian Prairies toward the Upper Midwest and western Ontario. Mid/upper west/southwesterly flow will remain somewhat enhanced (around 30-40 kt 850-700 mb flow) through around 00z before the system as a whole weakens. At the surface, a cold front will extend roughly north to south/southwest from western MN into southeast NE at midday. Ahead of this feature, southerly low-level flow will maintain 60s F dewpoints across IA into eastern MN/western WI. The warm sector will remain rather narrow due to generally high pressure and a drier boundary layer over much of the Midwest east of the MS River. Nevertheless, within the axis of greater moisture/low-level theta-e, around 1000-2000 J/kg MLCAPE is forecast. Organized thunderstorm clusters and line segments will pose a risk of isolated severe gusts and hail through early evening. The severe risk should rapidly diminish beyond 00z with loss of daytime heating, limited moisture/instability with eastward extent, and weakening deep-layer flow. ..Leitman.. 09/17/2024 Read more

WW 0674 Status Updates
STATUS FOR WATCH 0674 HAS NOT BEEN ISSUED YET Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1208 PM CDT Tue Sep 17 2024 Valid 181200Z - 191200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE GREAT PLAINS... ...SUMMARY... Isolated severe wind and hail are possible across a portion of the Great Plains during the late afternoon and evening on Wednesday. ...Great Plains... A stacked cyclone will slowly shift east/northeast from eastern MT to southern SK/MB on Wednesday into early Thursday. At the surface, a dryline will be oriented from the eastern Dakotas into western/central NE, then southward across western KS and into the OK/TX Panhandle vicinity. With time, a cold front will merge with this feature on the northern end across the Dakotas during the nighttime hours. Deep-layer south/southwesterly flow will remain somewhat enhanced across the northern/central Plains toward the Upper Midwest as the mid/upper trough shifts east. Around 30-35 kt effective shear magnitudes are forecast along the extent of the dryline. Meanwhile, surface dewpoints in the 60s will be maintained ahead of the surface boundary in a persistent southerly low-level warm advection regime. Midlevel temperatures are forecast to be somewhat warm, precluding steeper lapse rates. Nevertheless, 1000-2000 J/kg MLCAPE is expected, with the greatest instability expected near/north of the Mid-MO Valley. Weakening convection may be ongoing Wednesday morning in the vicinity of the Mid-MO valley, with areas of cloud cover extending northward into MN. Where stronger heating occurs, low-level convergence along the surface dryline and any remnant outflow boundaries may focus thunderstorm development during the afternoon. Large-scale ascent will be nebulous, with stronger forcing focused near/north of the international border. Instability and shear will decrease with southward extent into KS and the southern Plains. This will limit coverage and intensity of convection to some degree. Nevertheless, isolated strong to severe storms may pose a risk for locally damaging gusts and hail. Additional thunderstorms may develop overnight as the surface cold front overtakes the dryline from the far eastern Dakotas into MN. This activity will be driven by warm advection and likely be elevated. Severe potential currently appears low beyond the 03-06z time frame. ..Leitman.. 09/17/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1126 AM CDT Tue Sep 17 2024 Valid 171630Z - 181200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... Thunderstorms capable of producing scattered to numerous severe wind gusts and isolated large hail should occur this afternoon and evening across much of the High Plains. Some of the wind gusts may be significant (75+ mph). ...High Plains and Central/Southern Rockies... Expansions have been made to the Slight and Enhanced Risks across the northern/central High Plains to account for latest trends in guidance and observations. The Marginal Risk has also been expanded westward to include more of western CO and western/central WY, where isolated strong to severe winds are already ongoing with high-based convection. A strong upper trough/low over the Great Basin will pivot east-northeastward across the northern/central Rockies through this evening. An associated 50-60 kt mid-level jet will move eastward across the central/southern Rockies this afternoon, and over parts of the adjacent High Plains through this evening. As large-scale ascent with the upper trough and mid-level jet overspreads these regions, a surface low is forecast to deepen over eastern MT through this evening, while another low also develops over the central High Plains. A surface trough will extend southward from the central High Plains low, and it should sharpen as it develops eastward across the central/southern High Plains through the day. Greater low-level moisture, characterized by generally mid 50s to low 60s surface dewpoints, will gradually increase today along/east of the surface trough, while remaining more limited across the higher terrain of the central/southern Rockies. Moderate instability should develop to the east of the surface trough across much of the High Plains through peak afternoon heating. Strengthening deep-layer shear with the approach of the mid-level jet will support organized convection, including some potential for initial supercells across the northern High Plains (eastern MT and vicinity). Related threat for large hail will exist with any of this more discrete convection. Otherwise, thunderstorms will continue to develop this afternoon over the central/southern Rockies while producing isolated strong to severe wind gusts in a weakly unstable but strongly sheared environment. This activity will eventually spread off the higher terrain and into the central/southern High Plains. Steepened low-level lapse rates with robust daytime heating, along with more limited/shallow low-level moisture along/west of the surface trough, will likely support a gradually increasing severe wind threat with the high-based convection spreading east-northeastward across the southern/central Rockies. As these clusters and linear segments encounter greater low-level moisture and related instability along/east of the surface trough across the High Plains late this afternoon into early evening, the threat for scattered to numerous severe wind gusts should increase. This may particularly be the case across parts of the central High Plains, where the best combination of steepened low-level lapse rates, moderate instability, moderate to strong deep-layer shear, and greatest linear convective signal exists in 12Z guidance. Some chance for isolated gusts of 75+ mph may also be realized across this region with the more intense clusters spreading east-northeastward in tandem with the mid-level jet. The threat for severe winds is expected to gradually decrease with eastward extent across the Plains this evening as convection encounters increasing MLCIN with nocturnal cooling of the boundary layer. ...Florida... A weak mid/upper-level low will remain centered over the Southeast today. Modest mid-level westerly flow will persist over FL on the southern periphery of the upper low. Scattered to numerous thunderstorms should develop later this afternoon along/south of a remnant front, and along the Atlantic Coast sea breeze. Even with daytime heating of a rather moist low-level airmass, poor mid-level lapse rates should temper updraft intensities to some extent, even as moderate instability develops. That said, the stronger cores may be capable of producing isolated strong to damaging winds, with 20-25 kt of deep-layer shear aiding in modest thunderstorm organization. Some adjustments have been made to the Marginal Risk across parts of the FL Peninsula, based on latest observational trends and 12Z guidance. ...Southeast Virginia/Northeast North Carolina... A weak convective band is ongoing across far northeast NC into southeast VA, on the northeast side of a mid/upper-level low over the Southeast. Occasional strong/gusty winds may occur with the more robust cores this afternoon as the convective band pivots further into southeast VA. Even so, weak instability, modest low/mid-level flow, and related weak shear should temper overall thunderstorm organization. Accordingly, severe wind potential should remain low. ..Gleason/Moore.. 09/17/2024 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1128 AM CDT Tue Sep 17 2024 Valid 171700Z - 181200Z ...17z Update... No changes. Spotty elevated conditions are possible owing to strong southerly winds ahead of a cold front. Strong gusts may linger after the frontal passage and with shower/thunderstorms expected later today. Fire concerns will remain highest within patchy dry fuels across the southern most portions of the NE panhandle where less rainfall and lower humidity recoveries have occurred. See the prior discussion. ..Lyons.. 09/17/2024 .PREV DISCUSSION... /ISSUED 0156 AM CDT Tue Sep 17 2024/ ...Synopsis... A large-scale trough, accompanied by strong deep-layer south-southwesterly flow, will overspread the northern/central Rockies and adjacent High Plains. A related lee cyclone will deepen near western SD, promoting a tight pressure gradient and 20-25 mph sustained southerly surface winds (with higher gusts) over portions of western NE during the afternoon. Here, diurnal heating along the western edge of the richer boundary-layer moisture plume should yield 20-30 percent RH. Despite these marginal RH reductions, the strong/gusty winds will still favor a few hours of elevated fire-weather conditions, before a cold front and related precipitation overspread the area during the evening. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Tue Sep 17 13:58:02 UTC 2024.