Severe Storms

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0652 PM CST Thu Feb 08 2024 Valid 090100Z - 091200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDWEST... ...SUMMARY... A few strong/severe thunderstorms remain possible this evening across parts of southeast Wisconsin, northern Illinois, and the southern Lake Michigan vicinity. ...01z Update... Strong 500mb speed max is translating northeast across IL toward northern IN in association with a midlevel short-wave trough that is currently located over the upper MS Valley. This feature appears to be influencing strong/severe convection over the upper Midwest, especially across southern WI/northern IL. Very steep lapse rates are noted north of the jet, due in large part to very cold 500mb temperatures, and some boundary-layer heating. While surface dew points have held in the mid-upper 40s, surface-based parcels have proven buoyant, and several supercells evolved within the aforementioned corridor of strong convection. Latest radar data suggests the strongest convection will soon spread across southern Lake MI where buoyancy is weaker. This should lead to weaker updrafts over the next few hours and the prospect for severe should wane with eastward progression this evening. ..Darrow.. 02/09/2024 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0652 PM CST Thu Feb 08 2024 Valid 090100Z - 091200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDWEST... ...SUMMARY... A few strong/severe thunderstorms remain possible this evening across parts of southeast Wisconsin, northern Illinois, and the southern Lake Michigan vicinity. ...01z Update... Strong 500mb speed max is translating northeast across IL toward northern IN in association with a midlevel short-wave trough that is currently located over the upper MS Valley. This feature appears to be influencing strong/severe convection over the upper Midwest, especially across southern WI/northern IL. Very steep lapse rates are noted north of the jet, due in large part to very cold 500mb temperatures, and some boundary-layer heating. While surface dew points have held in the mid-upper 40s, surface-based parcels have proven buoyant, and several supercells evolved within the aforementioned corridor of strong convection. Latest radar data suggests the strongest convection will soon spread across southern Lake MI where buoyancy is weaker. This should lead to weaker updrafts over the next few hours and the prospect for severe should wane with eastward progression this evening. ..Darrow.. 02/09/2024 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0652 PM CST Thu Feb 08 2024 Valid 090100Z - 091200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDWEST... ...SUMMARY... A few strong/severe thunderstorms remain possible this evening across parts of southeast Wisconsin, northern Illinois, and the southern Lake Michigan vicinity. ...01z Update... Strong 500mb speed max is translating northeast across IL toward northern IN in association with a midlevel short-wave trough that is currently located over the upper MS Valley. This feature appears to be influencing strong/severe convection over the upper Midwest, especially across southern WI/northern IL. Very steep lapse rates are noted north of the jet, due in large part to very cold 500mb temperatures, and some boundary-layer heating. While surface dew points have held in the mid-upper 40s, surface-based parcels have proven buoyant, and several supercells evolved within the aforementioned corridor of strong convection. Latest radar data suggests the strongest convection will soon spread across southern Lake MI where buoyancy is weaker. This should lead to weaker updrafts over the next few hours and the prospect for severe should wane with eastward progression this evening. ..Darrow.. 02/09/2024 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0652 PM CST Thu Feb 08 2024 Valid 090100Z - 091200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDWEST... ...SUMMARY... A few strong/severe thunderstorms remain possible this evening across parts of southeast Wisconsin, northern Illinois, and the southern Lake Michigan vicinity. ...01z Update... Strong 500mb speed max is translating northeast across IL toward northern IN in association with a midlevel short-wave trough that is currently located over the upper MS Valley. This feature appears to be influencing strong/severe convection over the upper Midwest, especially across southern WI/northern IL. Very steep lapse rates are noted north of the jet, due in large part to very cold 500mb temperatures, and some boundary-layer heating. While surface dew points have held in the mid-upper 40s, surface-based parcels have proven buoyant, and several supercells evolved within the aforementioned corridor of strong convection. Latest radar data suggests the strongest convection will soon spread across southern Lake MI where buoyancy is weaker. This should lead to weaker updrafts over the next few hours and the prospect for severe should wane with eastward progression this evening. ..Darrow.. 02/09/2024 Read more

No watches are valid as of Thu Feb 8 23:46:02 UTC 2024.

No Mesoscale Discussions are in effect as of Thu Feb 8 23:46:02 UTC 2024.

MD 0114 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR NORTH-CENTRAL IL
Mesoscale Discussion 0114 NWS Storm Prediction Center Norman OK 0444 PM CST Thu Feb 08 2024 Areas affected...north-central IL Concerning...Severe potential...Watch unlikely Valid 082244Z - 082345Z Probability of Watch Issuance...20 percent SUMMARY...Localized risk for a brief tornado or two may focus through 6pm CST across north-central IL. DISCUSSION...A focused mesoscale corridor across north-central IL is becoming slightly more favorable for mesocyclones and the potential for a brief tornado over the next hour or so. The latest forecast soundings show rapid mid-level cooling (500 mb temperatures plunging into the minus mid 20s deg C). Surface analysis shows a slightly more moisture-rich airmass with dewpoints near 50 deg F across north-central IL. The small surface temperature/dewpoint spreads and adequate buoyancy and enlarged hodographs all suggest the potential for a narrow window of opportunity for a brief tornado or two during the next hour or so. ..Smith/Hart.. 02/08/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LOT...ILX...DVN... LAT...LON 41118942 41488880 41418846 41048848 40708902 40638950 40788965 41118942 Read more

MD 0113 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF NORTHERN IL INTO EXTREME EASTERN IA/SOUTHERN WI
Mesoscale Discussion 0113 NWS Storm Prediction Center Norman OK 0253 PM CST Thu Feb 08 2024 Areas affected...Parts of northern IL into extreme eastern IA/southern WI Concerning...Severe potential...Watch unlikely Valid 082053Z - 082330Z Probability of Watch Issuance...20 percent SUMMARY...A supercell or two may develop later this afternoon. Large hail, gusty winds, and possibly a tornado will all be possible, though coverage of the threat is expected to remain isolated. DISCUSSION...Convection is gradually deepening within a cumulus field this afternoon from eastern IA/northeast MO into western IL, in advance of a mid/upper-level trough approaching the upper MS Valley. Low-level moisture remains rather modest across the region, with surface dewpoints generally in the mid/upper 40s F. However, seasonably strong diurnal heating beneath cold temperatures aloft is supporting MLCAPE of around 500 J/kg, along with diminishing MLCINH. Destabilization should spread into a larger portion of northern IL and southern WI through late afternoon, in conjunction with eastward progression of the midlevel cold pool. The primary midlevel vorticity maximum and attendant surface cyclone are moving northeastward across MN, and large-scale ascent may remain rather modest across the effective warm sector. However, a low-amplitude shortwave is moving through the base of the mid/upper-level trough near the IA/MO border, and may aid in thunderstorm development as any remaining convective inhibition is removed. Strong deep-layer shear across the region will conditionally support organized convection, and a supercell or two may eventually evolve out of initial storm development. Steep tropospheric lapse rates will support large hail and locally gusty winds with the strongest storms. Also, despite less than ideal low-level moisture, a tornado cannot be ruled out given the presence of favorable low-level shear and lapse rates. At this time, coverage of the severe threat is expected to remain rather isolated. ..Dean/Goss.. 02/08/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LOT...ILX...MKX...DVN...ARX... LAT...LON 42549087 42829082 43078992 42928936 42378892 41368878 40758891 40618938 40569005 40959076 41299078 42549087 Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0338 PM CST Thu Feb 08 2024 Valid 101200Z - 161200Z Early in the extended forecast period, a strong western US trough is forecast to deepen over the southern Plains before ejecting into the central and southern US early next week. Strong low pressure is expected to develop over the southern Rockies and track eastward, bringing widespread precipitation to the southern and central US. The exception will be across parts of South TX. Here, dry and breezy conditions may support some potential for critical fire-weather conditions through early next week. Otherwise, active mid-level flow will favor a transition to cooler and wetter conditions through the remainder of next week. This will limit the risk for critical fire-weather conditions. ...Southern Plains to south TX... As low pressure intensifies this weekend, gusty downslope winds are expected to develop from the southern Plains, toward the Rio Grande Valley, and eventually Deep South TX. Sheltered from the highest expected precipitation, and within the dry warm sector, afternoon RH values below 25% appear likely from D3/Sat through D5/Mon. The combination of dry downslope and breezy conditions may support elevated to locally critical fire-weather concerns through the weekend and into early next week. However, significant uncertainty remains regarding the availability of dry fuels. Preceding days of dry and breezy may allow for some curing ahead of the favorable meteorological conditions. Still, confidence in more widespread critical fire-weather conditions is too low to introduce probabilities. Elsewhere, fire-weather concerns appear low through the remainder of the forecast period as much cooler/wetter conditions and weaker winds are expected to develop. ..Lyons.. 02/08/2024 ...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 0338 PM CST Thu Feb 08 2024 Valid 101200Z - 161200Z Early in the extended forecast period, a strong western US trough is forecast to deepen over the southern Plains before ejecting into the central and southern US early next week. Strong low pressure is expected to develop over the southern Rockies and track eastward, bringing widespread precipitation to the southern and central US. The exception will be across parts of South TX. Here, dry and breezy conditions may support some potential for critical fire-weather conditions through early next week. Otherwise, active mid-level flow will favor a transition to cooler and wetter conditions through the remainder of next week. This will limit the risk for critical fire-weather conditions. ...Southern Plains to south TX... As low pressure intensifies this weekend, gusty downslope winds are expected to develop from the southern Plains, toward the Rio Grande Valley, and eventually Deep South TX. Sheltered from the highest expected precipitation, and within the dry warm sector, afternoon RH values below 25% appear likely from D3/Sat through D5/Mon. The combination of dry downslope and breezy conditions may support elevated to locally critical fire-weather concerns through the weekend and into early next week. However, significant uncertainty remains regarding the availability of dry fuels. Preceding days of dry and breezy may allow for some curing ahead of the favorable meteorological conditions. Still, confidence in more widespread critical fire-weather conditions is too low to introduce probabilities. Elsewhere, fire-weather concerns appear low through the remainder of the forecast period as much cooler/wetter conditions and weaker winds are expected to develop. ..Lyons.. 02/08/2024 ...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 0338 PM CST Thu Feb 08 2024 Valid 101200Z - 161200Z Early in the extended forecast period, a strong western US trough is forecast to deepen over the southern Plains before ejecting into the central and southern US early next week. Strong low pressure is expected to develop over the southern Rockies and track eastward, bringing widespread precipitation to the southern and central US. The exception will be across parts of South TX. Here, dry and breezy conditions may support some potential for critical fire-weather conditions through early next week. Otherwise, active mid-level flow will favor a transition to cooler and wetter conditions through the remainder of next week. This will limit the risk for critical fire-weather conditions. ...Southern Plains to south TX... As low pressure intensifies this weekend, gusty downslope winds are expected to develop from the southern Plains, toward the Rio Grande Valley, and eventually Deep South TX. Sheltered from the highest expected precipitation, and within the dry warm sector, afternoon RH values below 25% appear likely from D3/Sat through D5/Mon. The combination of dry downslope and breezy conditions may support elevated to locally critical fire-weather concerns through the weekend and into early next week. However, significant uncertainty remains regarding the availability of dry fuels. Preceding days of dry and breezy may allow for some curing ahead of the favorable meteorological conditions. Still, confidence in more widespread critical fire-weather conditions is too low to introduce probabilities. Elsewhere, fire-weather concerns appear low through the remainder of the forecast period as much cooler/wetter conditions and weaker winds are expected to develop. ..Lyons.. 02/08/2024 ...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 0338 PM CST Thu Feb 08 2024 Valid 101200Z - 161200Z Early in the extended forecast period, a strong western US trough is forecast to deepen over the southern Plains before ejecting into the central and southern US early next week. Strong low pressure is expected to develop over the southern Rockies and track eastward, bringing widespread precipitation to the southern and central US. The exception will be across parts of South TX. Here, dry and breezy conditions may support some potential for critical fire-weather conditions through early next week. Otherwise, active mid-level flow will favor a transition to cooler and wetter conditions through the remainder of next week. This will limit the risk for critical fire-weather conditions. ...Southern Plains to south TX... As low pressure intensifies this weekend, gusty downslope winds are expected to develop from the southern Plains, toward the Rio Grande Valley, and eventually Deep South TX. Sheltered from the highest expected precipitation, and within the dry warm sector, afternoon RH values below 25% appear likely from D3/Sat through D5/Mon. The combination of dry downslope and breezy conditions may support elevated to locally critical fire-weather concerns through the weekend and into early next week. However, significant uncertainty remains regarding the availability of dry fuels. Preceding days of dry and breezy may allow for some curing ahead of the favorable meteorological conditions. Still, confidence in more widespread critical fire-weather conditions is too low to introduce probabilities. Elsewhere, fire-weather concerns appear low through the remainder of the forecast period as much cooler/wetter conditions and weaker winds are expected to develop. ..Lyons.. 02/08/2024 ...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 0338 PM CST Thu Feb 08 2024 Valid 101200Z - 161200Z Early in the extended forecast period, a strong western US trough is forecast to deepen over the southern Plains before ejecting into the central and southern US early next week. Strong low pressure is expected to develop over the southern Rockies and track eastward, bringing widespread precipitation to the southern and central US. The exception will be across parts of South TX. Here, dry and breezy conditions may support some potential for critical fire-weather conditions through early next week. Otherwise, active mid-level flow will favor a transition to cooler and wetter conditions through the remainder of next week. This will limit the risk for critical fire-weather conditions. ...Southern Plains to south TX... As low pressure intensifies this weekend, gusty downslope winds are expected to develop from the southern Plains, toward the Rio Grande Valley, and eventually Deep South TX. Sheltered from the highest expected precipitation, and within the dry warm sector, afternoon RH values below 25% appear likely from D3/Sat through D5/Mon. The combination of dry downslope and breezy conditions may support elevated to locally critical fire-weather concerns through the weekend and into early next week. However, significant uncertainty remains regarding the availability of dry fuels. Preceding days of dry and breezy may allow for some curing ahead of the favorable meteorological conditions. Still, confidence in more widespread critical fire-weather conditions is too low to introduce probabilities. Elsewhere, fire-weather concerns appear low through the remainder of the forecast period as much cooler/wetter conditions and weaker winds are expected to develop. ..Lyons.. 02/08/2024 ...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 0338 PM CST Thu Feb 08 2024 Valid 101200Z - 161200Z Early in the extended forecast period, a strong western US trough is forecast to deepen over the southern Plains before ejecting into the central and southern US early next week. Strong low pressure is expected to develop over the southern Rockies and track eastward, bringing widespread precipitation to the southern and central US. The exception will be across parts of South TX. Here, dry and breezy conditions may support some potential for critical fire-weather conditions through early next week. Otherwise, active mid-level flow will favor a transition to cooler and wetter conditions through the remainder of next week. This will limit the risk for critical fire-weather conditions. ...Southern Plains to south TX... As low pressure intensifies this weekend, gusty downslope winds are expected to develop from the southern Plains, toward the Rio Grande Valley, and eventually Deep South TX. Sheltered from the highest expected precipitation, and within the dry warm sector, afternoon RH values below 25% appear likely from D3/Sat through D5/Mon. The combination of dry downslope and breezy conditions may support elevated to locally critical fire-weather concerns through the weekend and into early next week. However, significant uncertainty remains regarding the availability of dry fuels. Preceding days of dry and breezy may allow for some curing ahead of the favorable meteorological conditions. Still, confidence in more widespread critical fire-weather conditions is too low to introduce probabilities. Elsewhere, fire-weather concerns appear low through the remainder of the forecast period as much cooler/wetter conditions and weaker winds are expected to develop. ..Lyons.. 02/08/2024 ...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 0338 PM CST Thu Feb 08 2024 Valid 101200Z - 161200Z Early in the extended forecast period, a strong western US trough is forecast to deepen over the southern Plains before ejecting into the central and southern US early next week. Strong low pressure is expected to develop over the southern Rockies and track eastward, bringing widespread precipitation to the southern and central US. The exception will be across parts of South TX. Here, dry and breezy conditions may support some potential for critical fire-weather conditions through early next week. Otherwise, active mid-level flow will favor a transition to cooler and wetter conditions through the remainder of next week. This will limit the risk for critical fire-weather conditions. ...Southern Plains to south TX... As low pressure intensifies this weekend, gusty downslope winds are expected to develop from the southern Plains, toward the Rio Grande Valley, and eventually Deep South TX. Sheltered from the highest expected precipitation, and within the dry warm sector, afternoon RH values below 25% appear likely from D3/Sat through D5/Mon. The combination of dry downslope and breezy conditions may support elevated to locally critical fire-weather concerns through the weekend and into early next week. However, significant uncertainty remains regarding the availability of dry fuels. Preceding days of dry and breezy may allow for some curing ahead of the favorable meteorological conditions. Still, confidence in more widespread critical fire-weather conditions is too low to introduce probabilities. Elsewhere, fire-weather concerns appear low through the remainder of the forecast period as much cooler/wetter conditions and weaker winds are expected to develop. ..Lyons.. 02/08/2024 ...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 0338 PM CST Thu Feb 08 2024 Valid 101200Z - 161200Z Early in the extended forecast period, a strong western US trough is forecast to deepen over the southern Plains before ejecting into the central and southern US early next week. Strong low pressure is expected to develop over the southern Rockies and track eastward, bringing widespread precipitation to the southern and central US. The exception will be across parts of South TX. Here, dry and breezy conditions may support some potential for critical fire-weather conditions through early next week. Otherwise, active mid-level flow will favor a transition to cooler and wetter conditions through the remainder of next week. This will limit the risk for critical fire-weather conditions. ...Southern Plains to south TX... As low pressure intensifies this weekend, gusty downslope winds are expected to develop from the southern Plains, toward the Rio Grande Valley, and eventually Deep South TX. Sheltered from the highest expected precipitation, and within the dry warm sector, afternoon RH values below 25% appear likely from D3/Sat through D5/Mon. The combination of dry downslope and breezy conditions may support elevated to locally critical fire-weather concerns through the weekend and into early next week. However, significant uncertainty remains regarding the availability of dry fuels. Preceding days of dry and breezy may allow for some curing ahead of the favorable meteorological conditions. Still, confidence in more widespread critical fire-weather conditions is too low to introduce probabilities. Elsewhere, fire-weather concerns appear low through the remainder of the forecast period as much cooler/wetter conditions and weaker winds are expected to develop. ..Lyons.. 02/08/2024 ...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 0154 PM CST Thu Feb 08 2024 Valid 082000Z - 091200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF FAR EASTERN IOWA...NORTHERN ILLINOIS...AND SOUTHERN WISCONSIN... ...SUMMARY... A few strong/severe thunderstorms remain possible this afternoon through early evening across parts of far eastern Iowa, northern Illinois, southern Wisconsin, and the southern Lake Michigan vicinity. ...20Z Update... Recent surface observations show upper 40s surface dewpoints present across southern/central IL and vicinity, with clearing occurring across parts of eastern IA and western/central IL beneath a mid-level dry slot. Recent visible satellite imagery also shows shallow cu development across northeastern MO and central/eastern IA as large-scale ascent attendant to an upper trough overspreads the warm/moist sector. Current expectations are for isolated, low-topped thunderstorms to develop by 22-23Z across far eastern IA and northern IL. Even though low-level moisture will likely remain shallow/limited, with surface dewpoints generally in the mid to upper 40s, rather cold mid-level temperatures and steepened lapse rates aloft should still aid in the development of around 500 J/kg of MLCAPE. Coupled with strong deep-layer shear, this weak instability should support organized convection, including the potential for a supercell or two. Isolated severe hail, strong/damaging winds, and perhaps a tornado all appear possible with this activity as it spreads quickly northeastward across northern IL and southern WI through the early evening before weakening. Given the limited thermodynamic environment and latest surface observations, have maintained the Marginal Risk with no changes. ..Gleason.. 02/08/2024 .PREV DISCUSSION... /ISSUED 1030 AM CST Thu Feb 08 2024/ ...Synopsis... A mid-level short-wave trough now crossing the Middle Missouri Valley/central Plains will continue progressing northeastward today and tonight, while a second feature now in the vicinity of the Lower Colorado Valley shifts eastward through the period. Meanwhile, upper ridging over the East will be shunted progressively eastward by the aforementioned advance of short-wave troughs farther west. At the surface, a rather deep (990 mb) surface cyclone is currently analyzed near the ND/SD/MN border intersection, with a cold front extending southward across the Middle Missouri Valley into Kansas. This boundary, and the advance of the upper trough, may support isolated late afternoon strong/potentially severe convective development across eastern Iowa/northwestern Illinois. Elsewhere, showers and scattered thunderstorms are expected to evolve across the Four Corners states ahead of the aforementioned upper trough, and overnight thunder may evolve within an area of broad/weak QG ascent over parts of the Lower Mississippi and Tennessee Valleys. Severe weather is not expected in these areas. ...Eastern Iowa/northern Illinois/southern Wisconsin vicinity... Low-level moisture remains a primary uncertainty today, with respect to potential strong/severe storm development. Dewpoints remain in the upper 30s/low 40s across the Iowa/Illinois area, where model forecast soundings -- particularly the RAP -- have consistently indicated upper 40s to low 50s dewpoints by late afternoon. This degree of moistening still appears to be a bit aggressive, with middle to upper 40s largely anticipated. With that said, very cold air aloft/steep lapse rates will continue to overspread this region, and the deep-layer wind field is conditionally quite supportive of severe/supercell storms. At this time, we will maintain MRGL risk and all-hazard, low-probability outlook. A couple of storms may develop by late afternoon, in the eastern Iowa/northwestern Illinois vicinity, and then shift eastward/east-northeastward through early evening, before weakening. However, evolution of moisture through the day will be closely watched, as the more aggressive RAP model solution -- should it appear more likely to occur -- would require consideration for an upgrade to the outlook at 20Z. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0154 PM CST Thu Feb 08 2024 Valid 082000Z - 091200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF FAR EASTERN IOWA...NORTHERN ILLINOIS...AND SOUTHERN WISCONSIN... ...SUMMARY... A few strong/severe thunderstorms remain possible this afternoon through early evening across parts of far eastern Iowa, northern Illinois, southern Wisconsin, and the southern Lake Michigan vicinity. ...20Z Update... Recent surface observations show upper 40s surface dewpoints present across southern/central IL and vicinity, with clearing occurring across parts of eastern IA and western/central IL beneath a mid-level dry slot. Recent visible satellite imagery also shows shallow cu development across northeastern MO and central/eastern IA as large-scale ascent attendant to an upper trough overspreads the warm/moist sector. Current expectations are for isolated, low-topped thunderstorms to develop by 22-23Z across far eastern IA and northern IL. Even though low-level moisture will likely remain shallow/limited, with surface dewpoints generally in the mid to upper 40s, rather cold mid-level temperatures and steepened lapse rates aloft should still aid in the development of around 500 J/kg of MLCAPE. Coupled with strong deep-layer shear, this weak instability should support organized convection, including the potential for a supercell or two. Isolated severe hail, strong/damaging winds, and perhaps a tornado all appear possible with this activity as it spreads quickly northeastward across northern IL and southern WI through the early evening before weakening. Given the limited thermodynamic environment and latest surface observations, have maintained the Marginal Risk with no changes. ..Gleason.. 02/08/2024 .PREV DISCUSSION... /ISSUED 1030 AM CST Thu Feb 08 2024/ ...Synopsis... A mid-level short-wave trough now crossing the Middle Missouri Valley/central Plains will continue progressing northeastward today and tonight, while a second feature now in the vicinity of the Lower Colorado Valley shifts eastward through the period. Meanwhile, upper ridging over the East will be shunted progressively eastward by the aforementioned advance of short-wave troughs farther west. At the surface, a rather deep (990 mb) surface cyclone is currently analyzed near the ND/SD/MN border intersection, with a cold front extending southward across the Middle Missouri Valley into Kansas. This boundary, and the advance of the upper trough, may support isolated late afternoon strong/potentially severe convective development across eastern Iowa/northwestern Illinois. Elsewhere, showers and scattered thunderstorms are expected to evolve across the Four Corners states ahead of the aforementioned upper trough, and overnight thunder may evolve within an area of broad/weak QG ascent over parts of the Lower Mississippi and Tennessee Valleys. Severe weather is not expected in these areas. ...Eastern Iowa/northern Illinois/southern Wisconsin vicinity... Low-level moisture remains a primary uncertainty today, with respect to potential strong/severe storm development. Dewpoints remain in the upper 30s/low 40s across the Iowa/Illinois area, where model forecast soundings -- particularly the RAP -- have consistently indicated upper 40s to low 50s dewpoints by late afternoon. This degree of moistening still appears to be a bit aggressive, with middle to upper 40s largely anticipated. With that said, very cold air aloft/steep lapse rates will continue to overspread this region, and the deep-layer wind field is conditionally quite supportive of severe/supercell storms. At this time, we will maintain MRGL risk and all-hazard, low-probability outlook. A couple of storms may develop by late afternoon, in the eastern Iowa/northwestern Illinois vicinity, and then shift eastward/east-northeastward through early evening, before weakening. However, evolution of moisture through the day will be closely watched, as the more aggressive RAP model solution -- should it appear more likely to occur -- would require consideration for an upgrade to the outlook at 20Z. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0154 PM CST Thu Feb 08 2024 Valid 082000Z - 091200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF FAR EASTERN IOWA...NORTHERN ILLINOIS...AND SOUTHERN WISCONSIN... ...SUMMARY... A few strong/severe thunderstorms remain possible this afternoon through early evening across parts of far eastern Iowa, northern Illinois, southern Wisconsin, and the southern Lake Michigan vicinity. ...20Z Update... Recent surface observations show upper 40s surface dewpoints present across southern/central IL and vicinity, with clearing occurring across parts of eastern IA and western/central IL beneath a mid-level dry slot. Recent visible satellite imagery also shows shallow cu development across northeastern MO and central/eastern IA as large-scale ascent attendant to an upper trough overspreads the warm/moist sector. Current expectations are for isolated, low-topped thunderstorms to develop by 22-23Z across far eastern IA and northern IL. Even though low-level moisture will likely remain shallow/limited, with surface dewpoints generally in the mid to upper 40s, rather cold mid-level temperatures and steepened lapse rates aloft should still aid in the development of around 500 J/kg of MLCAPE. Coupled with strong deep-layer shear, this weak instability should support organized convection, including the potential for a supercell or two. Isolated severe hail, strong/damaging winds, and perhaps a tornado all appear possible with this activity as it spreads quickly northeastward across northern IL and southern WI through the early evening before weakening. Given the limited thermodynamic environment and latest surface observations, have maintained the Marginal Risk with no changes. ..Gleason.. 02/08/2024 .PREV DISCUSSION... /ISSUED 1030 AM CST Thu Feb 08 2024/ ...Synopsis... A mid-level short-wave trough now crossing the Middle Missouri Valley/central Plains will continue progressing northeastward today and tonight, while a second feature now in the vicinity of the Lower Colorado Valley shifts eastward through the period. Meanwhile, upper ridging over the East will be shunted progressively eastward by the aforementioned advance of short-wave troughs farther west. At the surface, a rather deep (990 mb) surface cyclone is currently analyzed near the ND/SD/MN border intersection, with a cold front extending southward across the Middle Missouri Valley into Kansas. This boundary, and the advance of the upper trough, may support isolated late afternoon strong/potentially severe convective development across eastern Iowa/northwestern Illinois. Elsewhere, showers and scattered thunderstorms are expected to evolve across the Four Corners states ahead of the aforementioned upper trough, and overnight thunder may evolve within an area of broad/weak QG ascent over parts of the Lower Mississippi and Tennessee Valleys. Severe weather is not expected in these areas. ...Eastern Iowa/northern Illinois/southern Wisconsin vicinity... Low-level moisture remains a primary uncertainty today, with respect to potential strong/severe storm development. Dewpoints remain in the upper 30s/low 40s across the Iowa/Illinois area, where model forecast soundings -- particularly the RAP -- have consistently indicated upper 40s to low 50s dewpoints by late afternoon. This degree of moistening still appears to be a bit aggressive, with middle to upper 40s largely anticipated. With that said, very cold air aloft/steep lapse rates will continue to overspread this region, and the deep-layer wind field is conditionally quite supportive of severe/supercell storms. At this time, we will maintain MRGL risk and all-hazard, low-probability outlook. A couple of storms may develop by late afternoon, in the eastern Iowa/northwestern Illinois vicinity, and then shift eastward/east-northeastward through early evening, before weakening. However, evolution of moisture through the day will be closely watched, as the more aggressive RAP model solution -- should it appear more likely to occur -- would require consideration for an upgrade to the outlook at 20Z. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0154 PM CST Thu Feb 08 2024 Valid 082000Z - 091200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF FAR EASTERN IOWA...NORTHERN ILLINOIS...AND SOUTHERN WISCONSIN... ...SUMMARY... A few strong/severe thunderstorms remain possible this afternoon through early evening across parts of far eastern Iowa, northern Illinois, southern Wisconsin, and the southern Lake Michigan vicinity. ...20Z Update... Recent surface observations show upper 40s surface dewpoints present across southern/central IL and vicinity, with clearing occurring across parts of eastern IA and western/central IL beneath a mid-level dry slot. Recent visible satellite imagery also shows shallow cu development across northeastern MO and central/eastern IA as large-scale ascent attendant to an upper trough overspreads the warm/moist sector. Current expectations are for isolated, low-topped thunderstorms to develop by 22-23Z across far eastern IA and northern IL. Even though low-level moisture will likely remain shallow/limited, with surface dewpoints generally in the mid to upper 40s, rather cold mid-level temperatures and steepened lapse rates aloft should still aid in the development of around 500 J/kg of MLCAPE. Coupled with strong deep-layer shear, this weak instability should support organized convection, including the potential for a supercell or two. Isolated severe hail, strong/damaging winds, and perhaps a tornado all appear possible with this activity as it spreads quickly northeastward across northern IL and southern WI through the early evening before weakening. Given the limited thermodynamic environment and latest surface observations, have maintained the Marginal Risk with no changes. ..Gleason.. 02/08/2024 .PREV DISCUSSION... /ISSUED 1030 AM CST Thu Feb 08 2024/ ...Synopsis... A mid-level short-wave trough now crossing the Middle Missouri Valley/central Plains will continue progressing northeastward today and tonight, while a second feature now in the vicinity of the Lower Colorado Valley shifts eastward through the period. Meanwhile, upper ridging over the East will be shunted progressively eastward by the aforementioned advance of short-wave troughs farther west. At the surface, a rather deep (990 mb) surface cyclone is currently analyzed near the ND/SD/MN border intersection, with a cold front extending southward across the Middle Missouri Valley into Kansas. This boundary, and the advance of the upper trough, may support isolated late afternoon strong/potentially severe convective development across eastern Iowa/northwestern Illinois. Elsewhere, showers and scattered thunderstorms are expected to evolve across the Four Corners states ahead of the aforementioned upper trough, and overnight thunder may evolve within an area of broad/weak QG ascent over parts of the Lower Mississippi and Tennessee Valleys. Severe weather is not expected in these areas. ...Eastern Iowa/northern Illinois/southern Wisconsin vicinity... Low-level moisture remains a primary uncertainty today, with respect to potential strong/severe storm development. Dewpoints remain in the upper 30s/low 40s across the Iowa/Illinois area, where model forecast soundings -- particularly the RAP -- have consistently indicated upper 40s to low 50s dewpoints by late afternoon. This degree of moistening still appears to be a bit aggressive, with middle to upper 40s largely anticipated. With that said, very cold air aloft/steep lapse rates will continue to overspread this region, and the deep-layer wind field is conditionally quite supportive of severe/supercell storms. At this time, we will maintain MRGL risk and all-hazard, low-probability outlook. A couple of storms may develop by late afternoon, in the eastern Iowa/northwestern Illinois vicinity, and then shift eastward/east-northeastward through early evening, before weakening. However, evolution of moisture through the day will be closely watched, as the more aggressive RAP model solution -- should it appear more likely to occur -- would require consideration for an upgrade to the outlook at 20Z. Read more