853 ACUS01 KWNS 190058 SWODY1 SPC AC 190056 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0756 PM CDT Tue Mar 18 2025 Valid 190100Z - 191200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST KANSAS TO FAR EASTERN IOWA... ...SUMMARY... Isolated, marginally severe hail is possible by late tonight in a corridor from north central Kansas through central Iowa. ...Discussion... 00Z Surface analysis shows a 989mb surface low in west-central Kansas this evening. Ahead of this surface low, a low-level jet is strengthening (now 50 kts below 1km on the KICT VWP). This low-level jet is forecast to strengthen to 65 to 70 knots by 06Z which will be crucial for low-level moistening and thunderstorm potential later tonight. The 00Z RAOB from TOP showed a very dry profile. However, slightly better moisture is in place across central Oklahoma with a 8C dewpoint at 850mb at OUN. Forecast guidance continues to indicate that enough of this moisture will advect north into warm frontal zone across northeast Kansas and Iowa for weak to moderate instability by 08-10Z. If sufficient moistening occurs for 1000 J/kg MUCAPE early Wednesday morning, supercells capable of large hail will be possible given 40-45 knots of effective shear. Expanded the marginal slightly east this outlook to account for latest HRRR placement of the strongest storms early Wednesday morning. ..Bentley.. 03/19/2025 $$  089 ACUS11 KWNS 190532 SWOMCD SPC MCD 190532 NEZ000-KSZ000-COZ000-190930- Mesoscale Discussion 0239 NWS Storm Prediction Center Norman OK 1232 AM CDT Wed Mar 19 2025 Areas affected...Northeast Colorado into northwest Kansas into Nebraska Concerning...Blizzard Valid 190532Z - 190930Z SUMMARY...The onset of blizzard conditions is occurring across northeast CO; blizzard conditions will spread east and become more widespread through the early morning hours. DISCUSSION...Surface observations and web cams across northeast CO and adjacent areas of KS and NE are beginning to report significant visibility reductions below 1/2 mile as a combination of cold air advection and wet-bulb cooling support rapid cooling and saturation of low-level temperature profiles across the region. This comes as an intense surface low begins to mature to the east across central/western KS with 25-35 mph northerly gradient winds. Downstream across northern KS and southern NE, temperatures remain well above freezing, but similar rapid cooling/saturation is expected over the next few hours as sub-freezing temperatures are advected south and precipitation becomes more widespread and intense within the deformation/frontogenetical zone of the cyclone. Latest CAM guidance continues to suggest the potential for organized snow banding across northern KS into southern/central NE between 06-12 UTC with snowfall rates between 1-2 in/hour. Despite the relatively warm temperatures for a winter storm, blowing snow model output suggests that this combination of heavy snowfall rates and strong northerly winds (gusting between 40-60 mph) will support widespread visibility reductions below 1/4 mile with periods of whiteout conditions. ..Moore.. 03/19/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...OAX...ICT...GID...LBF...DDC...GLD...PUB...BOU... CYS... LAT...LON 40259814 39749845 39289877 38999908 38779952 38689982 38570048 38490119 38500186 38590247 38890310 39180356 39700378 40160385 40690367 41010312 41170255 41370177 41440121 41620032 42009861 42069803 42019755 41859718 41539698 41199690 40919713 40719747 40259814  608 ACUS02 KWNS 190553 SWODY2 SPC AC 190551 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1251 AM CDT Wed Mar 19 2025 Valid 201200Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorm development will be possible on Thursday in parts of the Mid-Atlantic and northern Rockies. A severe threat is not expected. ...DISCUSSION... At mid-levels on Thursday, a trough will move across the Ohio and Tennessee Valleys, as a fetch of southwest flow strengthens along the East Coast. At the surface, a pre-frontal trough will move across the Atlantic Coastal Plains. Ahead of the front, surface dewpoints are expected to reach the 50s F across the Mid-Atlantic, where weak destabilization will occur. Forecast soundings near the moist axis Thursday afternoon in central Virginia have MUCAPE peaking around 250 J/kg. As the exit region of the mid-level jet passes by, 0-6 km shear is forecast to be in the 80 to 90 knot range. Although thunderstorms will be possible across parts of the Mid-Atlantic Thursday afternoon, the instability is expected to be too weak for a severe threat. Elsewhere, isolated thunderstorms will be possible ahead of a shortwave mid-level trough, across parts of the northern Rockies and northern High Plains. No severe threat is expected across the continental U.S. Thursday and Thursday night. ..Broyles.. 03/19/2025 $$  581 ACUS01 KWNS 190557 SWODY1 SPC AC 190555 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Wed Mar 19 2025 Valid 191200Z - 201200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS CENTRAL ILLINOIS INTO FAR WESTERN INDIANA... ...SUMMARY... Scattered severe thunderstorms are possible on Wednesday across parts of central Illinois to western Indiana from mid-afternoon to early evening. Several tornadoes, large hail, and damaging wind gusts will be possible. ...Synopsis... A strong mid-level low will move from northeast Kansas this morning to Lower Michigan by 12Z Thursday. A strong mid-level jet streak along the southeastern periphery of this area of low pressure will translate from northeast Oklahoma to central Illinois. Meanwhile a surface low within the left exit region of this upper-level jet will move from northeast Kansas to north-central Illinois. ...Central Illinois into north-central Illinois and western Indiana... A rapidly changing environment is forecast across Illinois today. Extensive cloudcover is expected across the state for much of the day as low-level moisture streams north within a narrow corridor ahead of the cold front. However, by mid to late afternoon, some clearing is expected which may allow for some brief heating and destabilization across central Illinois. In fact, the HRRR shows what appears to be a dryline by mid afternoon. Mid-level temperatures will be very cold (-22C at 500mb and -4C at 700mb) which will allow for rapid destabilization with only slight heating. Once destabilization begins ahead of the cold front/dry line, expect thunderstorm development. The wind profile across central and northern Illinois will support supercells, but the intensity of these supercells will be modulated by the instability. 250-500 J/kg MLCAPE will likely be sufficient for supercells capable of all severe weather hazards. However, if greater destabilization occurs, such as shown by the 00Z HRRR/ 03Z RAP, an even more volatile environment would be present. 56-57F dewpoints would support 1000+ J/kg MLCAPE which is very significant in the low-topped environment with an EL below 30kft. HRRR/RAP soundings show STP values around 2-3 with very favorable low-level hodograph shapes. Therefore, in the higher instability scenario, multiple tornadic supercells would be possible with the potential for strong (EF2+) tornadoes. While uncertainties remain regarding dewpoints and the amount of clearing/heating along/ahead of the front, an enhanced risk upgrade seems prudent given the expectation for several supercells capable of all hazards and the conditional potential for a more volatile environment. ...Southern Indiana southward to MS/AL... Additional thunderstorms are expected to develop along the cold front across Indiana at the nose of the mid-level jet streak during the evening as rapid ascent and mid-level cooling erodes inhibition. Forecast sounding show an environment favorable for supercells capable of all severe weather hazards to persist across Indiana before eventually outrunning the instability somewhere near the Ohio border. Mid-level cooling will not be as great farther south across KY/TN and into MS/AL. However, greater low-level moisture (upper 50s to low 60s dewpoints) should compensate with a few scattered supercells possible with a primary threat of large hail and damaging wind gusts during the evening. ..Bentley.. 03/19/2025 $$  960 ACUS03 KWNS 190717 SWODY3 SPC AC 190715 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0215 AM CDT Wed Mar 19 2025 Valid 211200Z - 221200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms will be possible on Friday across parts of the Pacific Northwest, but no severe threat is expected. ...DISCUSSION... A shortwave mid-level trough will move into the Pacific Northwest on Friday. Ahead of this feature, large-scale ascent and mid-level moisture may be sufficient for isolated thunderstorm development across parts of Washington, northern Oregon and northern Idaho. No severe threat is expected to develop. ..Broyles.. 03/19/2025 $$  650 ACUS48 KWNS 190852 SWOD48 SPC AC 190850 Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0350 AM CDT Wed Mar 19 2025 Valid 221200Z - 271200Z ...DISCUSSION... ...Saturday/Day 4 to Sunday/Day 5... A mid-level trough will move through the central U.S. on Saturday and Sunday, as moisture advection takes place across the southern Plains, lower Mississippi Valley and Ark-La-Tex. Thunderstorm development will likely take place ahead of the trough on Sunday afternoon and evening, along the northern edge of the moist airmass from the Red River Valley eastward into the lower Mississippi Valley. A threat for large hail and severe wind gusts will be possible within the more organized components of a developing MCS. The MCS is forecast to move southeastward through the lower Mississippi valley during the overnight period. ...Monday/Day 6 to Wednesday/Day 8... On Monday, the trough is forecast to become amplified across the Ohio and Tennessee Valleys, as a cold front moves southward through the Gulf Coast states. Isolated severe storms could occur near the central Gulf Coast early in the day, but the majority of the storms are expected to move offshore into the Gulf. On Tuesday and Wednesday, surface high pressure is forecast to settle over the eastern half of the nation. This dry and cool airmass will make conditions unfavorable for thunderstorms over most of the continental U.S. ..Broyles.. 03/19/2025  205 ACUS11 KWNS 190938 SWOMCD SPC MCD 190937 ILZ000-IAZ000-191130- Mesoscale Discussion 0240 NWS Storm Prediction Center Norman OK 0437 AM CDT Wed Mar 19 2025 Areas affected...Parts of IA into extreme northwest IL Concerning...Severe potential...Watch unlikely Valid 190937Z - 191130Z Probability of Watch Issuance...5 percent SUMMARY...Isolated hail and strong thunderstorm gusts are possible early this morning. DISCUSSION...An arc of elevated convection has recently intensified from west-central into eastern IA, aided by ascent attendant to a powerful cyclone moving across KS, and within an environment characterized by MUCAPE of around 500 J/kg and cold temperatures aloft. Increasing midlevel flow northeast of the cyclone is supporting effective shear of 30-40 kt, assuming a sufficiently deep updraft. Some transient storm organization will remain possible through the early morning, with a favorable thermodynamic environment for production of small to isolated severe hail, as noted earlier north of Omaha. Localized strong gusts also cannot be ruled out with any more organized and sustained cells. ..Dean/Thompson.. 03/19/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DVN...ARX...DMX...FSD... LAT...LON 42609501 43149325 42999171 41919009 40439084 41449350 41949503 42189528 42609501  962 ACUS11 KWNS 191054 SWOMCD SPC MCD 191054 MNZ000-IAZ000-NEZ000-SDZ000-KSZ000-191600- Mesoscale Discussion 0241 NWS Storm Prediction Center Norman OK 0554 AM CDT Wed Mar 19 2025 Areas affected...Parts of western/central KS into central/eastern NE...northwest IA...and extreme southeast SD/south-central MN Concerning...Blizzard Valid 191054Z - 191600Z SUMMARY...Blizzard conditions will gradually spread eastward through the morning. Snow rates of 1-2+ inches per hour are possible, along with widespread 50-60+ mph gusts. DISCUSSION...Blizzard conditions are ongoing this morning from southwest/south-central NE into western KS, to the northwest of a powerful 987 mb cyclone centered over northeast KS. Very strong deep-layer ascent will continue to support heavy precipitation rates through the morning, aided by very favorable low/midlevel frontogenesis, and the presence of elevated buoyancy and regenerative convection along the eastern periphery of heavier precipitation, near the midlevel dry slot. The heaviest precipitation rates will gradually shift eastward through the morning, in conjunction with the movement of the cyclone, while low-level cold advection and strong ascent result in cooling of the column and a changeover to snow in areas that are currently in the mid/upper 30s F. Meanwhile, very strong low-level flow increasing to near/above 70 kt at 1 km AGL (as noted on the KUEX VWP) will continue to support wind gusts in the 50-70 mph range (as already noted through the night across parts of KS/NE), resulting in widespread blowing snow and blizzard conditions. Short-term guidance generally suggests that the heaviest snow rates will become focused from central/northern KS into northeast NE/northwest IA later this morning. Areas within the most intense snow bands may experience rates of 1-2+ inches per hour, along with wind gusts near/above 60 mph, near-zero visibility, and occasional lightning. A rather sharp gradient in snow rates is expected along the eastern periphery of the heavier precipitation, though the very strong wind gusts may result in blizzard conditions even in areas that experience only light to moderate snow. ..Dean.. 03/19/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MPX...DMX...FSD...OAX...TOP...ICT...GID...LBF... DDC...GLD... LAT...LON 38510077 40719967 42119789 43089633 43699472 43879405 43959356 42839368 42219429 40569637 39399748 38399811 38009859 37749935 37659990 37690043 37810075 38510077  501 ACUS01 KWNS 191246 SWODY1 SPC AC 191245 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0745 AM CDT Wed Mar 19 2025 Valid 191300Z - 201200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FOR PARTS OF CENTRAL/NORTHERN ILLINOIS AND WEST CENTRAL INDIANA... ...SUMMARY... Scattered severe thunderstorms are possible this afternoon/evening from central/northern Illinois to western Indiana. A few tornadoes, large hail, and damaging wind gusts will be possible. ...IL/IN this afternoon into early tonight... A deep (989 mb) cyclone near the northeast KS/northwest MO border will move northeastward to northern IL by this evening and Lower MI overnight, in conjunction with a deep midlevel trough and 100+ kt midlevel jet streak. Elevated convection is ongoing this morning in a zone of focused ascent with warm advection/frontogenesis across IA, where isolated large hail may occur with MUCAPE around 500 J/kg and steep midlevel lapse rates/cool midlevel temperatures. The warm sector of the cyclone is characterized by a narrow/modest corridor of returning moisture (low-mid 50s boundary-layer dewpoints) that will overspread MO/IL through the afternoon. Surface heating in cloud breaks, continued moisture advection and relatively cool midlevel temperatures will all contribute to warm sector destabilization (MLCAPE 500-750 J/kg) through the afternoon across IL. Surface-based thunderstorm development will become probable by early-mid afternoon in a broken band along and just ahead of a remnant dryline moving from MO into IL, and storms will subsequently move eastward/northeastward into IN by early tonight before weakening gradually. The deeper buoyancy profiles will be on the cyclonic side of the midlevel jet, where 500 mb temperatures will be < -20 C. Forecast wind profiles suggest supercell potential with long hodographs (effective bulk shear vectors >50 kt), and sufficient low-level hodograph curvature/shear for tornado potential. The primary uncertainty centers of the degree of low-level moistening/destabilization, and the current forecast represents a conditional/reasonable worst case scenario. Otherwise, occasional large hail (1-1.5 inches in diameter) will be possible in IL this afternoon/evening, and the threat for damaging gusts (60-70 mph) and a couple of tornadoes will persist into IN through early tonight. ...TN/MS/AL this afternoon/evening... Boundary-layer dewpoints will slowly increase to the upper 50s/lower 60s ahead of the surface wind shift moving across AR/LA this afternoon. Forcing for ascent should be sufficient to remove the cap, allowing some deep convection in a broken band this afternoon/evening. Buoyancy will be relatively weak compared to the vertical shear, so it will be difficult to get sustained severe storms and isolated wind damage will be the most probable threat. ..Thompson/Dean.. 03/19/2025 $$  497 ACUS11 KWNS 191433 SWOMCD SPC MCD 191433 ILZ000-WIZ000-191630- Mesoscale Discussion 0242 NWS Storm Prediction Center Norman OK 0933 AM CDT Wed Mar 19 2025 Areas affected...parts of northeastern Iowa...northern Illinois...southern Wisconsin Concerning...Severe potential...Watch unlikely Valid 191433Z - 191630Z Probability of Watch Issuance...20 percent SUMMARY...Thunderstorms approaching the Greater Milwaukee and Chicago metropolitan areas may continue to pose a risk for small to marginally severe hail before weakening by midday into early afternoon. DISCUSSION...Observational data indicate some recent intensification of thunderstorm activity in an arcing northeastward advancing band spreading into/across parts of southern Wisconsin and northern Illinois. Based on forecast soundings, this convection is rooted within elevated moisture return and destabilization based near the 700 mb level, beneath an initial surge of cooling further aloft. Most unstable CAPE may be as high as 750+ J/kg along this corridor, with shear within the elevated convective layer strong, which may continue to support sub-severe to marginally severe hail in stronger cells another few hours. Into midday day, as activity spreads towards/into the Greater Milwaukee and Chicago vicinities, the latest Rapid Refresh suggests that this convection will probably tend to weaken as storm inflow trends less unstable. ..Kerr/Leitman.. 03/19/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LOT...MKX...DVN...ARX... LAT...LON 42819067 43178997 42848824 41578784 40938846 41208911 41958954 42819067  073 ACUS01 KWNS 191600 SWODY1 SPC AC 191559 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1059 AM CDT Wed Mar 19 2025 Valid 191630Z - 201200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FOR PARTS OF CENTRAL/NORTHERN ILLINOIS AND WEST CENTRAL INDIANA... ...SUMMARY... Scattered severe thunderstorms are possible this afternoon/evening from central/northern Illinois to western Indiana. A few tornadoes, large hail, and damaging wind gusts will be possible. ...IL/IN vicinity into early tonight... A deep (990mb) surface low over northwest MO this morning will continue to shift east into northern IL through late afternoon, and into IN/MI and southern Ontario overnight. Meanwhile, the exit region of a 90-100+ kt 500 mb jet will overspread IL/IN this afternoon into early evening. Cloud cover and elevated convection this morning across IA and northern IL, along with lofted dust moving over the region may inhibit heating to some degree into the afternoon. Furthermore, boundary layer moisture is expected to remain modest, most likely in the 51-54 F range given 15z upstream observations in the low 50s F. If any stronger heating occurs, mixing may further limit dewpoints from climbing into the mid/upper 50s F as suggested by some forecast guidance. Nevertheless, cold temperatures aloft (-17 C on 12z RAOBs from DVN) will support steep midlevel lapse rates and modest destabilization into the early afternoon. A dryline is noted across central MO at 15z. This feature will continue to sweep east into the afternoon and become a focus for stronger thunderstorm development across IL by 18-19z. Vertical shear will be favorable for supercells given elongated hodographs with enlarged, looping low-level hodographs. These vertical wind profiles are already evident in VWP data from DVN and LOT where a west to east oriented surface warm front is roughly aligned across east-central IA/northern IL. Evolution of modest boundary layer moisture will be key for determining the tornado risk this afternoon across IL/IN. If dewpoints can reach 55-56 F, a localized area of enhanced tornado potential may develop. While some risk for tornadoes will still exist with lower dewpoints, the risk would be more muted and likely less intense. Given the conditional risk for a strong tornado or two, will maintain the 10 percent SIG tornado risk. Otherwise, somewhat low-topped supercells will also pose a risk for damaging gusts of 60-70 mph and isolated large hail up to 1-1.5 inches in diameter. Isolated convection may develop southward along the dryline/cold front into western/central KY by late afternoon before convection weakens after sunset. ...TN/MS/AL vicinity this afternoon/evening... Dewpoints have gradually increased into the mid 50s late this morning. Continued warm advection ahead of a wind shift this afternoon should allow dewpoints to reach the upper 50s to low 60s F. While forcing for ascent will be weak compared to further north, it should be sufficient to erode capping in the persistent warm advection regime. Instability will remain modest, generally near/less than 500 J/kg MLCAPE. While vertical shear will be quite strong, this should limit updraft intensity/longevity. A broken band of storms may still pose a risk for a few strong gusts. ..Leitman/Bunting.. 03/19/2025 $$  529 ACUS11 KWNS 191622 SWOMCD SPC MCD 191621 ILZ000-IAZ000-MOZ000-191845- Mesoscale Discussion 0243 NWS Storm Prediction Center Norman OK 1121 AM CDT Wed Mar 19 2025 Areas affected...central Illinois Concerning...Severe potential...Watch possible Valid 191621Z - 191845Z Probability of Watch Issuance...60 percent SUMMARY...A gradual intensification of thunderstorm activity is likely across parts of southeastern Iowa into west central into central Illinois through 1-3 PM CDT. This may include increasing potential for a couple of tornadoes, severe hail and locally strong surface gusts. Trends are being monitored for the possibility of a watch, which appears more probable across parts of central/eastern Illinois later this afternoon. DISCUSSION...Scattered, modest convective development has been occurring to the east-northeast of a deep, occluding cyclone now centered north of Kansas City. This has been focused along a dryline, which may continue to become better defined into early afternoon, as the Rapid Refresh suggests that the trailing cold front may not quite overtake it. The leading edge of the primary cooling at mid-levels is contributing to steepening lapse rates along the dryline and, with a gradual moistening (surface dew points increasing through the lower 50s) of the boundary-layer ahead of it, appreciable further destabilization is expected. It appears that this may include mixed-layer CAPE increasing to 500-1000 j/kg in a corridor from near the triple point across the southeastern Iowa vicinity into central Illinois. As this occurs, initially scattered, low-topped thunderstorm development is likely to undergo a gradual intensification, beneath an intense south-southwesterly mid/upper jet. Low-level hodographs remain rather modest to weak, and Rapid Refresh forecast soundings suggest that this may not change much until later this afternoon across parts of east central Illinois (roughly near/east of the Bloomington and Decatur vicinities). However, it is possible that ambient vertical vorticity and steepening low-level lapse rates along the dryline, near the triple point, may support potential for at least a couple of generally brief/weak tornadoes, in addition to severe hail and locally strong surface gusts. ..Kerr/Leitman.. 03/19/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LOT...ILX...LSX...DVN... LAT...LON 41469066 41088906 38938848 38998954 39438987 39639122 40889185 41469066  542 ACUS02 KWNS 191637 SWODY2 SPC AC 191636 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1136 AM CDT Wed Mar 19 2025 Valid 201200Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorm development will be possible on Thursday in parts of the Mid-Atlantic and northern Rockies. A severe threat is not expected. ...Synopsis... A mid-level trough will traverse the Rockies as a second upper trough ejects into the Atlantic tomorrow (Thursday). A surface cold front will accompany the East Coast trough, immediately preceded by marginal low-level moisture (e.g. low 50s F surface dewpoints). Scant buoyancy, driven by the meager low-level moisture, may encourage the development of a few thunderstorms from the Mid Atlantic to Carolina Piedmont region. Given relatively strong flow just above the boundary layer, strong wind gusts may occur with a few of the storms, but confidence in any appreciable severe gust coverage is too low for the addition of severe probabilities at this time. Otherwise, the only other location where lightning flashes may be observed is over the northern Rockies, where a plume of cold temperatures aloft, associated with the western trough, may promote enough buoyancy (albeit scant) to support a few thunderstorms. ..Squitieri.. 03/19/2025 $$  424 ACUS11 KWNS 191717 SWOMCD SPC MCD 191717 WIZ000-MIZ000-MNZ000-192015- Mesoscale Discussion 0244 NWS Storm Prediction Center Norman OK 1217 PM CDT Wed Mar 19 2025 Areas affected...Central WI...southern MI Upper Peninsula Concerning...Heavy snow Valid 191717Z - 192015Z SUMMARY...Heavy snow, with rates of 1 to 2 inches per hour, will continue and expand northeast across the discussion area this afternoon. DISCUSSION...Upper-level low pressure over northeast KS will continue moving steadily east as an accompanying surface low moves from northern MO into northern IL by late afternoon. As surface temperatures cool, snow will expand in coverage in response to increasing large-scale ascent and spread northeast through late afternoon. Intensifying frontogenetic forcing within the 850-700 mb layer will contribute to snowfall rates of one inch per hour becoming widespread, and weak elevated buoyancy/embedded convective elements will result in areas of locally higher rates of up to 2 inches per hour. As the surface low moves east-northeast, strong/gusty north to northeast winds of 30 to 45 mph with higher gusts will result in areas of whiteout conditions. ..Bunting.. 03/19/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MQT...GRB...DLH...ARX...MPX... LAT...LON 44879176 45958887 45948825 45868769 45548739 45218731 44858762 44588854 44408918 44069019 43859097 43959155 44229180 44429185 44679185 44879176  687 ACUS03 KWNS 191853 SWODY3 SPC AC 191852 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0152 PM CDT Wed Mar 19 2025 Valid 211200Z - 221200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms will be possible on Friday across parts of the Pacific Northwest and the Midwest, but no severe threat is expected. ...Synopsis... A pronounced, coupled mid-level/surface trough will traverse the Midwest into the OH Valley as a mid-level impulse tracks from the Pacific Northwest to the northern Rockies on Friday. Some of the latest guidance depicts a plume of cooler temperatures aloft accompanying the Midwest/OH Valley mid-level trough, which may support a few lightning flashes over these regions Friday into Friday night. Likewise, cooler temperatures aloft will overspread portions of the Pacific Northwest into the northern Rockies as this mid-level trough passes overhead, perhaps resulting in enough buoyancy to support a few lightning flashes. ..Squitieri.. 03/19/2025 $$  280 ACUS11 KWNS 191925 SWOMCD SPC MCD 191925 INZ000-KYZ000-TNZ000-ILZ000-192130- Mesoscale Discussion 0245 NWS Storm Prediction Center Norman OK 0225 PM CDT Wed Mar 19 2025 Areas affected...parts of southern Illinois and Indiana...western Kentucky Concerning...Severe potential...Watch possible Valid 191925Z - 192130Z Probability of Watch Issuance...60 percent SUMMARY...Thunderstorm development east of the Mississippi River, into areas south of the Ohio River, appears increasingly possible by 5-7 PM CDT, if not a bit earlier. This may include the evolution of a broken line with embedded supercells, posing at least the risk for severe hail and wind. DISCUSSION...From around the Greater St. Louis area southward, convective development along the dryline still appears suppressed by mid-level subsidence and warming to the east and south of the intense cyclonic mid-level jet nosing through the middle Mississippi Valley. However, better low-level moisture return (characterized by mid 50s F surface dew points) is ongoing across the Missouri Bootheel and adjacent portions of western Kentucky through southern Illinois. As this continues, coincident with the eastward progression of the mid-level trough, it appears that mid-level forcing for ascent and cooling aloft may gradually overcome inhibition and support increasing thunderstorm development, perhaps into areas south of the Ohio River by early evening. Rapid Refresh forecast soundings indicate considerable strengthening and enlargement of the low-level hodographs around this same time, though perhaps with a tendency for the hodographs to trend more linear as thunderstorms finally initiate with the removal of the mid-level inhibition. Regardless, strong deep-layer shear will be supportive of organized convection, including supercells, with potential to produce at least severe hail and wind. ..Kerr/Leitman.. 03/19/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LMK...OHX...IND...PAH... LAT...LON 36788895 38078861 38888669 38518637 37378714 36618804 36788895  811 ACUS01 KWNS 192000 SWODY1 SPC AC 191958 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Wed Mar 19 2025 Valid 192000Z - 201200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FOR PARTS OF CENTRAL/NORTHERN ILLINOIS AND WEST CENTRAL INDIANA... ...SUMMARY... Scattered severe thunderstorms are expected this afternoon/evening from central/northern Illinois to western Indiana. A few tornadoes, large hail, and damaging wind gusts will be possible. ...20Z Update... The primary change with this update was a southward extension of the Slight risk area to the TN/KY border. Current expectations are for a broken band of thunderstorms to track eastward into this area this afternoon into the evening. Here, filtered diurnal heating amid gradual boundary-layer moistening should yield enough low-level destabilization for a threat of scattered severe wind gusts and an embedded tornado risk -- given favorable low-level hodograph size and curvature. Elsewhere, severe probabilities were trimmed from the west behind the eastward-advancing dryline. For details on the near-term severe risk, reference Tornado Watch #57 and MCD #245. ..Weinman.. 03/19/2025 .PREV DISCUSSION... /ISSUED 1059 AM CDT Wed Mar 19 2025/ ...IL/IN vicinity into early tonight... A deep (990mb) surface low over northwest MO this morning will continue to shift east into northern IL through late afternoon, and into IN/MI and southern Ontario overnight. Meanwhile, the exit region of a 90-100+ kt 500 mb jet will overspread IL/IN this afternoon into early evening. Cloud cover and elevated convection this morning across IA and northern IL, along with lofted dust moving over the region may inhibit heating to some degree into the afternoon. Furthermore, boundary layer moisture is expected to remain modest, most likely in the 51-54 F range given 15z upstream observations in the low 50s F. If any stronger heating occurs, mixing may further limit dewpoints from climbing into the mid/upper 50s F as suggested by some forecast guidance. Nevertheless, cold temperatures aloft (-17 C on 12z RAOBs from DVN) will support steep midlevel lapse rates and modest destabilization into the early afternoon. A dryline is noted across central MO at 15z. This feature will continue to sweep east into the afternoon and become a focus for stronger thunderstorm development across IL by 18-19z. Vertical shear will be favorable for supercells given elongated hodographs with enlarged, looping low-level hodographs. These vertical wind profiles are already evident in VWP data from DVN and LOT where a west to east oriented surface warm front is roughly aligned across east-central IA/northern IL. Evolution of modest boundary layer moisture will be key for determining the tornado risk this afternoon across IL/IN. If dewpoints can reach 55-56 F, a localized area of enhanced tornado potential may develop. While some risk for tornadoes will still exist with lower dewpoints, the risk would be more muted and likely less intense. Given the conditional risk for a strong tornado or two, will maintain the 10 percent SIG tornado risk. Otherwise, somewhat low-topped supercells will also pose a risk for damaging gusts of 60-70 mph and isolated large hail up to 1-1.5 inches in diameter. Isolated convection may develop southward along the dryline/cold front into western/central KY by late afternoon before convection weakens after sunset. ...TN/MS/AL vicinity this afternoon/evening... Dewpoints have gradually increased into the mid 50s late this morning. Continued warm advection ahead of a wind shift this afternoon should allow dewpoints to reach the upper 50s to low 60s F. While forcing for ascent will be weak compared to further north, it should be sufficient to erode capping in the persistent warm advection regime. Instability will remain modest, generally near/less than 500 J/kg MLCAPE. While vertical shear will be quite strong, this should limit updraft intensity/longevity. A broken band of storms may still pose a risk for a few strong gusts. $$  967 ACUS11 KWNS 192037 SWOMCD SPC MCD 192037 INZ000-ILZ000-192230- Mesoscale Discussion 0246 NWS Storm Prediction Center Norman OK 0337 PM CDT Wed Mar 19 2025 Areas affected...eastern Illinois into far western Indiana Concerning...Tornado Watch 57... Valid 192037Z - 192230Z The severe weather threat for Tornado Watch 57 continues. SUMMARY...Strong to severe thunderstorm development is likely to continue to increase during the next few hours, including the potential for supercells with tornadoes across much of east central Illinois into the Indiana state border vicinity through 5-7 PM CDT. DISCUSSION...Aided by stronger mid-level forcing for ascent and cooling, within the exit region of the intense mid-level jet nosing through the middle Mississippi Valley, an intensifying and evolving broken line of thunderstorms appears likely to spread across and east of the Interstate 55 corridor of central Illinois through 21-22Z. This is where 20Z surface observations indicate that rapid (2-hourly in excess of 4 mb) surface pressure falls are maximized, and lower 50s surface dew points are being maintained with perhaps some further increase ongoing farther east, into the vicinity of the Indiana state border vicinity. More discrete thunderstorms are now initiating farther south, between Taylorville and Salem, which are likely to continue rapidly moving north-northeastward within 50-60 kt south-southwesterly deep-layer mean flow. Rapid Refresh forecast soundings continue to suggest that this will coincide with enlarging clockwise-curved low-level hodographs near/east of Kankakee, Champaign, Decatur vicinities, where south to southwesterly flow is forecast to intensify within the 850-700 mb layer through 22-00Z. And it still appears the low-level thermodynamic profiles may become conducive to supercell tornadoes, perhaps including a strong tornado or two. ..Kerr.. 03/19/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...IND...PAH...LOT...ILX...LSX... LAT...LON 41618831 41418744 38798741 38288815 38388861 40008935 41618831  033 ACUS11 KWNS 192157 SWOMCD SPC MCD 192156 INZ000-ILZ000-192330- Mesoscale Discussion 0247 NWS Storm Prediction Center Norman OK 0456 PM CDT Wed Mar 19 2025 Areas affected...parts of eastern Illinois and into western Indiana Concerning...Tornado Watch 57... Valid 192156Z - 192330Z The severe weather threat for Tornado Watch 57 continues. SUMMARY...Severe/isolated tornado risk continues across Tornado Watch 57, with the greatest short-term tornado potential appearing most likely over east-central Illinois and western Indiana. DISCUSSION...Latest radar loop shows scattered strong/locally severe storms in a north-south Zone centered over the eastern half of Illinois. Within this zone, modest CAPE but strong flow aloft will continue to support organized storms, and with dewpoints over the northern half of the watch in the low 50s, strong/damaging wind gusts appear to be the primary risk. Over southeastern portions of the watch -- i.e. east-central Illinois and into western Indiana -- slightly richer low-level moisture is evident, with mid 50s dewpoints prevalent. Here too, more substantial low-level veering with height is evident (surface to 1 KM shear 35 kt at this time is indicated at IND). These two factors suggest that greatest tornado risk within the WW may exist across this portion of the watch over the next 1 to 2 hours. With time, overall severe risk is forecast to shift gradually eastward in tandem with progression of the storms and associated cold front. New WW -- or WW extensions -- will likely need to be considered into more of Indiana over the next couple of hours. ..Goss.. 03/19/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...IWX...IND...PAH...LOT...ILX... LAT...LON 39378817 40248812 40818712 40668631 39798577 38998594 38498729 38658853 39378817  119 ACUS11 KWNS 192225 SWOMCD SPC MCD 192224 KYZ000-INZ000-ILZ000-200030- Mesoscale Discussion 0248 NWS Storm Prediction Center Norman OK 0524 PM CDT Wed Mar 19 2025 Areas affected...portions of the lower Ohio River Valley Concerning...Tornado Watch 58... Valid 192224Z - 200030Z The severe weather threat for Tornado Watch 58 continues. SUMMARY...Thunderstorms are beginning to develop across southeast Illinois into western Kentucky. These storms are expected to intensify and pose a severe threat as they move eastward across the lower Ohio River Valley over the next few hours. DISCUSSION...Very gradually deepening convection, cooling cloud-top temperatures, and occasional lightning flashes have been noted over the past 30-60 minutes across the lower OH River Valley. Despite the slow convective evolution thus far, a combination of steadily improving low-level moisture (in the form of mid 50s dewpoints) and increasing deep-layer ascent within the left-exit region of the mid-level jet should lead to a gradual increase in storm coverage over the next 1-2 hours across southern IN and western KY. Buoyancy within the narrow warm sector will remain fairly meager (around 500 J/kg MLCAPE), but low to mid-level winds have been increasing over the past hour with the approach of the mid-level jet, which is bolstering low to mid-level wind shear per regional VWPs. This favorable kinematic profile should compensate for the limited buoyancy and support organized convection downstream from where cells are currently developing. Given nearly 300 m2/s2 0-1 km SRH and 50-60 knot flow sampled within the lowest 1-2 km, severe gusts and tornadoes should remain the primary hazard. ..Moore.. 03/19/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LMK...IND...PAH... LAT...LON 36858879 37378858 38198811 38398792 38508771 38588640 38528602 38358581 37938585 37668601 37368625 37138646 37058674 36698840 36728869 36788878 36858879  342 ACUS11 KWNS 192334 SWOMCD SPC MCD 192334 ALZ000-TNZ000-KYZ000-MSZ000-200130- Mesoscale Discussion 0249 NWS Storm Prediction Center Norman OK 0634 PM CDT Wed Mar 19 2025 Areas affected...Western and middle Tennessee into northern Mississippi and northwest Alabama Concerning...Severe potential...Watch unlikely Valid 192334Z - 200130Z Probability of Watch Issuance...20 percent SUMMARY...Thunderstorm development is expected between 7-9 PM CDT across western Tennessee and northern to central Mississippi with a downstream risk for severe hail and damaging winds. The risk is expected to remain sufficiently isolated to preclude watch issuance. DISCUSSION...GOES visible imagery shows gradually deepening cumulus along and just ahead of a diffuse dryline/Pacific front from western TN southward into MS. This trend is expected to continue as mid-level temperatures continue to cool with the eastward progression of the primary trough axis, resulting in improving 700-500 mb lapse rates that will be more favorable for sustained convection. This trend is already being observed further north across the lower OH River Valley, suggesting that thunderstorm development is becoming more likely for areas further south. Modest surface moisture (mid 50s dewpoints) will continue to limit overall buoyancy values (MLCAPE should be maximized around 500-750 J/kg), but wind fields over the region are supporting elongated hodographs that will promote organization of the more intense updrafts. Weak off-boundary storm motions/deep-layer shear vectors suggest that a combination of semi-discrete cells and clusters is likely later this evening as storms move into middle TN and northwest AL. Given the convective environment and trends in latest CAM guidance, a few of the more intense cells/clusters may pose a severe hail/wind threat through the late evening. ..Moore/Hart.. 03/19/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...OHX...BMX...HUN...PAH...MEG...JAN... LAT...LON 32909031 35998919 36458887 36538846 36628750 36588700 36448652 36178623 35758610 35048619 34208674 33358759 32638848 32468899 32458937 32478982 32549002 32679022 32909031