Severe Storms

WW 146 SEVERE TSTM IA MN 192050Z - 200400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 146 NWS Storm Prediction Center Norman OK 350 PM CDT Wed Apr 19 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Northwest to north-central Iowa Far southwest Minnesota * Effective this Wednesday afternoon and evening from 350 PM until 1100 PM CDT. * Primary threats include... Scattered large hail and isolated very large hail events to 2 inches in diameter possible Isolated damaging wind gusts to 60 mph possible A tornado or two possible SUMMARY...A supercell cluster should develop northeast from the Mid-Missouri Valley and pose a primary threat of large hail north of the surface warm front. The severe thunderstorm watch area is approximately along and 45 statute miles north and south of a line from 50 miles west southwest of Worthington MN to 30 miles northeast of Fort Dodge IA. 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. && AVIATION...A few severe thunderstorms with hail surface and aloft to 2 inches. Extreme turbulence and surface wind gusts to 50 knots. A few cumulonimbi with maximum tops to 450. Mean storm motion vector 23030. ...Grams Read more

WW 0145 Status Updates
STATUS FOR WATCH 0145 HAS NOT BEEN ISSUED YET Read more

WW 145 TORNADO IA KS MO NE 192045Z - 200400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 145 NWS Storm Prediction Center Norman OK 345 PM CDT Wed Apr 19 2023 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Western Iowa Northeast Kansas Northwest Missouri Southeast Nebraska * Effective this Wednesday afternoon and evening from 345 PM until 1100 PM CDT. * Primary threats include... A few tornadoes possible Scattered large hail and isolated very large hail events to 3 inches in diameter likely Scattered damaging winds and isolated significant gusts to 75 mph possible SUMMARY...Multiple supercell clusters should develop across the Mid-Missouri Valley into northeast Kansas this evening. Greater tornado threat should be near the surface warm front, with very large hail the most probable threat in terms of coverage. The tornado watch area is approximately along and 60 statute miles east and west of a line from 25 miles east southeast of Manhattan KS to 35 miles north northeast of Denison IA. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU5). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Tornado Watch means conditions are favorable for tornadoes and 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. && AVIATION...Tornadoes and a few severe thunderstorms with hail surface and aloft to 3 inches. Extreme turbulence and surface wind gusts to 65 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 22030. ...Grams Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Wed Apr 19 2023 Valid 192000Z - 201200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS NORTHEAST KANSAS...SOUTHEAST NEBRASKA...NORTHWEST MISSOURI...AND SOUTHWEST IOWA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS CENTRAL OKLAHOMA INTO WESTERN NORTH TEXAS... ...SUMMARY... Multiple rounds of scattered severe thunderstorms are expected from late afternoon into tonight across the Mid-Missouri Valley. Very large hail is likely, and significant severe wind gusts along with a few tornadoes will be possible. A conditional threat for isolated significant severe storms also exists farther south into western/central Oklahoma and western north Texas this evening. ...Discussion... The only substantial changes this outlook update include the following: 1) shift the severe probabilities farther east where the dryline has moved east across parts of northern and western OK. 2) Reduced severe probabilities across northern OK/far south-central KS and bifurcated Slight-Risk equivalent severe probabilities into a northern and southern area. This change appears supported by both a strong consensus in model guidance showing the favored corridor for thunderstorms (severe) along the dryline to be over southwest and central OK later this afternoon/evening. Additionally, some of the model guidance simulating storms was aggressive with boundary-layer moisture compared to the 19 UTC Norman, OK raob (11.9 g/kg mean w). Specifically, the NSSL ARW high-resolution model was nearly 2 g/kg lowest 100 mb mean mixing ratio too moist. The 12 UTC FV3 model run depicted the boundary layer structure very well when compared to the observed raob. It remains plausible both based on the FV3 and observational trends that one or a couple of storms will develop along the dryline and potentially pose a severe hazard. Elsewhere, the forecast remains on track and no change was warranted. ..Smith.. 04/19/2023 .PREV DISCUSSION... /ISSUED 1139 AM CDT Wed Apr 19 2023/ ...Mid-MO Valley... Three rounds of severe potential appear increasingly evident across the Mid-MO Valley vicinity beginning in the late afternoon and continuing tonight. The first should consist of elevated thunderstorms north of the slow-moving/quasi-stationary warm front that is arcing east of the initial primary surface cyclone over southeast NE. This activity near the NE/SD/IA border will probably evolve into a couple of elevated supercells within an eastward-moving cluster, owing to favorable cloud-bearing shear along the northern gradient of the peak buoyancy plume across the central Great Plains. Large hail will be the primary hazard. A separate area of dryline to warm-sector storm development is anticipated towards the KS/NE/MO/IA border during the early evening in the exit region of a strengthening low-level jet in OK/KS/MO. This ascent combined with the boundary-layer thermal ridge from western OK to central/eastern KS should be enough to overcome the pronounced elevated mixed-layer across the Great Plains. 12Z NAM guidance remains terribly inconsistent with the 00Z ECMWF, recent RAP guidance, and comparison to surface observations. It is already much too cool with current temperatures with it's typical too cool/moist boundary layer. It appears more likely that a relatively well-mixed boundary layer within this portion of the warm/moist sector will be characterized by surface dew points from 58-61 F as storms form. This will seemingly support a mix of large hail, damaging wind gusts, and a couple tornadoes with supercells that initially form. Given a relatively confined buoyancy plume, regenerative convection is likely through the evening, yielding a broadening cluster with embedded supercell structures. Tonight, a third round of severe storms should develop near the south-central NE/north-central KS border. This should occur as a lee cyclone over the central High Plains shifts east, in association with a shortwave impulse progressing through the basal portion of the broader mid-level trough over the West. A surge of low-level moisture northwestward amid an intense 60-70 kt low-level jet should support emerging elevated supercell clusters that track east overnight, potentially merging with lingering convection downstream. Severe wind gusts and large hail will be the primary threats. ...Western/central OK into western north TX... Storm development is uncertain along the dryline during the late afternoon to early evening, given little in the way of height falls/forcing for ascent, and the presence of a substantial warm-sector cap. Storm initiation will rely on the depth of mixing with surface heating along the dryline, and on parcel residence time in the dryline zone of ascent. Flow in the 850-700 mb layer will be a bit more parallel to the dryline compared to yesterday, which may allow long enough residence times to reach an LFC. If storms form, the environment favors a threat of isolated very large hail with any sustained supercell. During the evening, substantial intensification of the low-level jet and an increase in boundary-layer moisture renders concern for a conditional strong tornado threat after dusk. Overall moisture appears a bit less compared to past nocturnal intense tornado events and confidence is low in whether a supercell or two can become established prior to increasing MLCIN during the late evening. As such, confidence in occurrence/coverage is low, but intensity is conditionally significant. Read more

MD 0560 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR FAR SOUTHEAST SD...FAR SOUTHWEST MN...FAR EASTERN NE...WESTERN IA...NORTHEAST KS...NORTHWEST MO
Mesoscale Discussion 0560 NWS Storm Prediction Center Norman OK 0245 PM CDT Wed Apr 19 2023 Areas affected...Far Southeast SD...Far Southwest MN...Far Eastern NE...Western IA...Northeast KS...Northwest MO Concerning...Severe potential...Watch likely Valid 191945Z - 192215Z Probability of Watch Issuance...95 percent SUMMARY...Thunderstorm development is anticipated across the Mid MO Valley later this afternoon. These storms will be capable of all severe hazards, including tornadoes and very large hail. Multiple watches will be needed to address this threat over the region. DISCUSSION...Recent surface analysis places a low about 25 miles west of LNK in southeast NE. A warm front extends northward from this low into more of east-central NE and then back eastward across central IA. Additionally, a cold front extends southwestward back through central KS to a triple point north of Medicine Lodge KS (P28). Visible satellite imagery has shown a trend towards increasingly agitated cumulus ahead of the surface low across eastern NE and downstream within the warm sector across IA. Temperatures have now reached the low to mid 70s across much of the warm sector, with dewpoints generally in the upper 50s to low 60s. Expectation is for modest heating to continue for the next few hours while the surface low shifts eastward and the warm front gradually lifts north. Resulting destabilization coupled with mesoscale ascent will likely result in thunderstorm initiation in and around the surface low and perhaps along the cold front into northeast KS. Steep lapse rate environment will support strong buoyancy and the potential for large to very large hail, particularly with initial development. A corridor of higher tornado risk appears possible near the warm front, where backed surface winds are more likely. Given the initially discrete storm mode, some tornado risk is anticipated ahead of the cold front and surface low as well. Thunderstorm may also develop north of the warm front as warm-air advection increases, with some potential for already developed storms to cross this boundary as well. Given the elevated character of these storms, hail will be the primary severe risk. ..Mosier/Grams.. 04/19/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MPX...DMX...EAX...FSD...OAX...TOP...ICT... LAT...LON 38319520 38499658 39109707 39669707 40929697 42339677 43039674 43439649 43649590 43649525 43429461 42899419 41589387 40159369 38679406 38319520 Read more

MD 0559 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR NORTHERN ILLINOIS TO SOUTHERN WISCONSIN
Mesoscale Discussion 0559 NWS Storm Prediction Center Norman OK 0242 PM CDT Wed Apr 19 2023 Areas affected...Northern Illinois to southern Wisconsin Concerning...Severe potential...Watch unlikely Valid 191942Z - 192145Z Probability of Watch Issuance...5 percent SUMMARY...Thunderstorms ongoing and developing within a strong warm air advection regime will likely continue to pose a severe hail threat for the next few hours. Watch issuance is not anticipated. DISCUSSION...A convective band across southern WI has maintained intensity over the past hour per GOES IR imagery. Additionally, new cell development is noted across northern IL in the vicinity of a surface warm front. Strong lift across this region is being driven by a deep zone of isentropic ascent, which is expected to continue through the next few hours ahead of the approaching upper wave to the west. MUCAPE across the region is expected to remain near 1000-2000 J/kg as differential warm advection in the 850-700 mb layer maintains steep mid-level lapse rates. With effective bulk shear near 40-45 knots, organized convection will remain possible and may pose an isolated large hail risk. While more isolated discrete cells/clusters are probable to the south of the convective band across WI, storm longevity remains questionable given observed lifespans of recent cells. The band itself is expected to gradually migrate east/southeast over the next few hours, and will continue to pose at least a transient hail threat as stronger updrafts embedded within the line develop. ..Moore/Grams.. 04/19/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LOT...ILX...MKX...DVN...ARX... LAT...LON 40519020 41459036 43399044 43898962 43718815 43548781 42558762 40638823 40018886 40108971 40519020 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0236 PM CDT Wed Apr 19 2023 Valid 201200Z - 211200Z ...CRITICAL FIRE WEATHER AREA FOR FOR PORTIONS OF CENTRAL NEW MEXICO... ...Central Appalachians... Dry southerly winds may support locally elevated fire-weather conditions Thursday afternoon over much of the central OH River Valley into the central Appalachians. While models differ on the coverage of RH below 30% owing to differences in cloud cover and mixing, at least some coverage of RH below 30% is expected Thursday afternoon. Surface winds of 15-20 mph may also overlap with some of the lower RH for a few hours as the surface low deepens over the upper Midwest. Recent fuel guidance trends have been drier than previously suggested, which lends additional confidence to at least a few hours of locally elevated fire-weather potential Thursday afternoon. An Elevated has been introduced given the potential for fire-weather concerns. ..Lyons.. 04/19/2023 .PREV DISCUSSION... /ISSUED 0221 AM CDT Wed Apr 19 2023/ ...Synopsis... A mid-level trough will deepen across the central U.S. tomorrow/Thursday, resulting in deep-layer westerly flow across the southern and central Plains. By afternoon peak heating, dry downslope flow will contribute to widespread 15+ mph sustained westerly surface winds amid 15-20 percent RH, necessitating the introduction of Elevated highlights from New Mexico into western Kansas. An enhanced corridor of 20+ mph sustained winds are likely across northern/central New Mexico toward the Texas Panhandle, where Critical highlights have also been added. At least locally Elevated conditions may develop across portions of the Ohio Valley during the afternoon as strong southerly flow will coincide with a deep, dry boundary layer. Central into eastern Kentucky seem to be the most likely location to experience Elevated conditions. However, the latest guidance has not come into consensus regarding how low RH will drop during the afternoon, with some guidance showing RH dropping to 25 percent and other members showing 40 percent values. As such, confidence is too low to introduce Elevated highlights this outlook. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Wed Apr 19 2023 Valid 201200Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF THE MIDDLE MISSISSIPPI VALLEY INTO THE ARKLATEX AND CENTRAL TEXAS... ...SUMMARY... Widely scattered severe thunderstorms capable of hail and severe gusts are possible from parts of mid Mississippi Valley southwestward into the Ark-La-Tex and central Texas Thursday afternoon and Thursday night. ...Synopsis... A mid-level low will migrate slowly eastward across the Upper Midwest with a larger-scale trough longitudinally located over the Great Plains. An embedded disturbance/mid-level speed max will quickly move from KS/NE Thursday morning to WI by early evening. In the low levels, a surface low will develop northeastward from IA into the Upper Great Lakes and occlude, while a trailing cold front will push east/southeast across the mid MS Valley into the southern Great Plains. ...Ozarks/Ark-La-Tex/Southern Plains... A cold front will bisect OK and extend north-northeastward into eastern KS/western MO during the morning and continue east-southeast through peak heating. A reservoir of adequately rich low-level moisture --characterized by mid-upper 60s dewpoints-- will reside across the Ozarks southward into north TX. Strong heating will contribute to a moderate to very unstable airmass by early-mid afternoon. MLCAPE is forecast to range from near 1000 J/kg over southern MO to 3500 J/kg over central TX. As the cap weakens near the front during peak heating, scattered thunderstorms are forecast to develop. Moderate to strong deep-layer shear will promote storm organization. Supercells capable of large to very large hail will be possible from north TX southward along the I-35 corridor into central TX. Additional storm development is likely during the evening with upscale growth in one or more bands of storms likely during the evening into the overnight. The severe risk will likely lessen as storms move east nearing the MS River and moving towards the Gulf Coast late. ...Mid MS Valley and WI... At the start of the Day-2 period, a 60-kt LLJ will be located over the lower MO Valley. This feature's associated warm-air advection will promote scattered showers/thunderstorms during the morning across northern MO into the eastern half of IA and parts of adjacent IL/WI during the morning. Elevated buoyancy amidst strong shear will lend a conditional risk for strong and locally severe thunderstorms. Isolated large hail and perhaps damaging gusts may accompany this activity. It remains a bit uncertain whether this early day thunderstorm activity will continue and/or additional storms will redevelop via cloud breaks/heating during the midday into the afternoon, especially with north extent. Nonetheless, it seems a severe risk may develop during the afternoon and perhaps linger into the evening with a broken band of storms from the mid MS Valley northward into WI. If greater destabilization can occur from IL into southern WI, a focused threat for damaging gusts and perhaps a tornado or two could materialize Thursday afternoon/early evening. Uncertainty is high regarding this scenario and will defer this possibility to later outlooks. ..Smith.. 04/19/2023 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1141 AM CDT Wed Apr 19 2023 Valid 191700Z - 201200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF NEW MEXICO ONTO THE SOUTHERN HIGH PLAINS.... ...Southern Plains... Minor adjustments have been made to the northern end of the Elevated and Critical areas across southern KS. The northward limit of critical fire-weather conditions is uncertain today given the cold front has progressed slightly farther south than previous guidance. Otherwise, the forecast remains unchanged. ...Mid Atlantic... Strong mid-level flow lingering over the eastern US may support a few hours of breezy winds across portions of NJ and southern NY State. RH values are expected to be only marginally supportive given cooler temperatures in the post-frontal air mass. However, with winds near 15 mph, at least a few hours of locally elevated fire-weather conditions may develop within areas of moderately receptive fuels. ..Lyons.. 04/19/2023 .PREV DISCUSSION... /ISSUED 0153 AM CDT Wed Apr 19 2023/ ...Synopsis... A mid-level trough will overspread the central U.S. today, resulting in surface low development and the eastward surge of a dryline during the afternoon. Widespread dry and windy conditions are expected in the post-dryline environment, with Critical highlights maintained where 20+ mph sustained westerly surface winds will overlap with 10-20 percent RH and dry fuels for several hours. Dry and windy conditions are also expected immediately behind the cold front across western into central Nebraska, where Elevated highlights remain. Here, dry downslope flow will contribute to overlapping 15 mph sustained northwesterly winds and 15-20 percent RH by afternoon peak heating. Elevated highlights have been adjusted where the aforementioned Elevated meteorological surface conditions coincide with dry fuels that have not experienced recent rainfall. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 1139 AM CDT Wed Apr 19 2023 Valid 191630Z - 201200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS MID-MO VALLEY... CORRECTED FOR HAIL AND CATEGORICAL LINES IN IL ...SUMMARY... Multiple rounds of scattered severe thunderstorms are expected from late afternoon into tonight across the Mid-Missouri Valley. Very large hail is likely, and significant severe wind gusts along with a few tornadoes will be possible. A conditional threat for isolated significant severe storms also exists farther south into western/central Oklahoma and western north Texas this evening. ...Mid-MO Valley... Three rounds of severe potential appear increasingly evident across the Mid-MO Valley vicinity beginning in the late afternoon and continuing tonight. The first should consist of elevated thunderstorms north of the slow-moving/quasi-stationary warm front that is arcing east of the initial primary surface cyclone over southeast NE. This activity near the NE/SD/IA border will probably evolve into a couple of elevated supercells within an eastward-moving cluster, owing to favorable cloud-bearing shear along the northern gradient of the peak buoyancy plume across the central Great Plains. Large hail will be the primary hazard. A separate area of dryline to warm-sector storm development is anticipated towards the KS/NE/MO/IA border during the early evening in the exit region of a strengthening low-level jet in OK/KS/MO. This ascent combined with the boundary-layer thermal ridge from western OK to central/eastern KS should be enough to overcome the pronounced elevated mixed-layer across the Great Plains. 12Z NAM guidance remains terribly inconsistent with the 00Z ECMWF, recent RAP guidance, and comparison to surface observations. It is already much too cool with current temperatures with it's typical too cool/moist boundary layer. It appears more likely that a relatively well-mixed boundary layer within this portion of the warm/moist sector will be characterized by surface dew points from 58-61 F as storms form. This will seemingly support a mix of large hail, damaging wind gusts, and a couple tornadoes with supercells that initially form. Given a relatively confined buoyancy plume, regenerative convection is likely through the evening, yielding a broadening cluster with embedded supercell structures. Tonight, a third round of severe storms should develop near the south-central NE/north-central KS border. This should occur as a lee cyclone over the central High Plains shifts east, in association with a shortwave impulse progressing through the basal portion of the broader mid-level trough over the West. A surge of low-level moisture northwestward amid an intense 60-70 kt low-level jet should support emerging elevated supercell clusters that track east overnight, potentially merging with lingering convection downstream. Severe wind gusts and large hail will be the primary threats. ...Western/central OK into western north TX... Storm development is uncertain along the dryline during the late afternoon to early evening, given little in the way of height falls/forcing for ascent, and the presence of a substantial warm-sector cap. Storm initiation will rely on the depth of mixing with surface heating along the dryline, and on parcel residence time in the dryline zone of ascent. Flow in the 850-700 mb layer will be a bit more parallel to the dryline compared to yesterday, which may allow long enough residence times to reach an LFC. If storms form, the environment favors a threat of isolated very large hail with any sustained supercell. During the evening, substantial intensification of the low-level jet and an increase in boundary-layer moisture renders concern for a conditional strong tornado threat after dusk. Overall moisture appears a bit less compared to past nocturnal intense tornado events and confidence is low in whether a supercell or two can become established prior to increasing MLCIN during the late evening. As such, confidence in occurrence/coverage is low, but intensity is conditionally significant. ..Grams/Thornton.. 04/19/2023 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0241 PM CDT Tue Apr 18 2023 Valid 182000Z - 191200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PARTS OF THE CENTRAL STATES... ...SUMMARY... Isolated severe thunderstorms are possible from parts of the southern Great Plains northward into the Mid Missouri Valley/Upper Midwest and westward into Wyoming. Large hail and severe wind gusts will be the hazards with the stronger storms late this afternoon into tonight. ...Discussion... No change is warranted to the previous convective outlook. ..Smith.. 04/18/2023 .PREV DISCUSSION... /ISSUED 1126 AM CDT Tue Apr 18 2023/ ...Central/southern Great Plains to Mid-MO Valley/Upper Midwest... Modified moisture return is occurring from the southern Great Plains ahead of a deepening lee cyclone over the central High Plains. But guidance has above-average spread in the degree of this return into KS and southern NE by early evening, lowering confidence in the overall environment and sustenance of deep convection given the stout elevated mixed-layer over the moist sector. Based on 12Z observed soundings, GOES PW imagery, and 16Z surface observations, it appears that the drier spectrum of guidance is more reasonable with the magnitude of this return, suggesting mid 40s to mid 50s surface dew points north of OK by 00Z. This should be adequate to support isolated high-based thunderstorms along the dryline in the western KS vicinity during the late afternoon to early evening. This activity will pose a threat for isolated large hail and localized severe wind gusts. Still, morning HRRR runs are insistent that even this scenario will fail, with effectively no sustained deep convection along the entire dryline. During the evening, a strengthening low-level jet will yield warm theta-e advection tonight. This might support any lingering dryline storms spreading northeast towards the Mid-MO Valley or more likely the development of elevated thunderstorms where ascent can overcome the stout elevated mixed-layer. Steep mid-level lapse rates and favorable cloud-layer shear will conditionally support a few elevated supercells, although the predominant convective mode should tend towards clusters northeast of the surface warm front. Isolated large hail appears to be the main threat. ...WY to western SD/NE... An elongated upper trough over the Northwest should consolidate across the northern Great Plains tonight. This will occur as a piece of the strong mid-level jet across northern/central CA and the Sierras ejects across the central Rockies to the Black Hills vicinity. This strengthening flow regime and large-scale ascent will aid in scattered high-based, low-topped convection across WY this afternoon and spreading into western SD/NE this evening. With surface dew points only in the 20s to low 30s, buoyancy will likely remain scant. But inverted-v thermodynamic profiles will support a threat for sporadic severe wind gusts. Read more

No watches are valid as of Tue Apr 18 19:46:02 UTC 2023.

No Mesoscale Discussions are in effect as of Tue Apr 18 19:46:02 UTC 2023.

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0150 PM CDT Tue Apr 18 2023 Valid 191200Z - 201200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE SOUTHERN HIGH PLAINS AND CENTRAL/EASTERN NEW MEXICO... The previous outlook remains valid with no major changes. See the prior discussion. ..Lyons.. 04/18/2023 .PREV DISCUSSION... /ISSUED 0120 AM CDT Tue Apr 18 2023/ ...Synopsis... A mid-level trough will eject into the Plains tomorrow/Wednesday, with surface lee troughing expected across the northern Plains, and surface low development across the southern Plains. Across the southern Plains, a dryline will rapidly advance eastward across western Oklahoma and Kansas, with widespread dry and windy conditions expected across the southern High Plains. Critical highlights have been added across much of New Mexico into far southeast Colorado into the Oklahoma and Texas Panhandles, where widespread 20 mph sustained westerly winds will overlap with 10-20 percent RH and dry fuels. Elevated highlights have also been introduced farther north across western into central Nebraska, where overlapping 15-20 percent RH and 15+ mph sustained northwesterly surface winds will occur behind a passing surface cold front. While portions of Nebraska may experience thunderstorms before the cold front moves through, these storms are expected to be isolated. As such, widespread appreciable rainfall accumulations appear unlikely, and fuels are expected to be receptive enough to support wildfire spread. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1229 PM CDT Tue Apr 18 2023 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF WESTERN OKLAHOMA AND INTO CENTRAL KANSAS AND INTO CENTRAL IOWA... ...SUMMARY... Severe thunderstorms with the potential for giant hail, a risk for a couple of tornadoes, and severe gusts will be possible late Wednesday afternoon into Wednesday night across parts of the central states. ...Central Great Plains into the mid-upper MS Valley... A stationary mid-level low over western ND and associated larger-scale trough over the Interior West, will result in a belt of strengthening southwesterly mid- to high-level flow across the central-southern Great Plains into parts of the Corn Belt. A surface low initially over ND will occlude and weaken while another surface low develops over the KS during the day. A frontal zone will extend from the northern low southward to near the IA/NE border and to the low over KS. A dryline will extend southward from central KS through western OK and west-central TX. Southerly low-level flow will advect moisture northward from the TX/OK into KS and eastern NE with surface dewpoints forecast to reach the upper 50s to near 60 deg F over western IA to the lower-mid 60s over central KS/western OK. Strong diurnal heating is forecast over the Great Plains in the warm sector ahead of a 70-kt 500-mb speed max forecast to move into KS during the overnight. Of particular note, a low-level thermal ridge is forecast to extend from the TX Panhandle northeastward into central KS abutting the dryline near the I-135 corridor. It is on the northeast periphery of the steep 0-3-km lapse rates and beneath the left exit region of the upper jet that convective initiation is most probable during the late afternoon/early evening. Forecast soundings show a moderate to very unstable boundary layer (MLCAPE ranging from 2000 J/kg near the IA/NE border to 3000 J/kg near the dryline). As the cap weakens by mid-late afternoon, widely spaced CI attempts will likely become evident. It seems plausible isolated storms will eventually develop near/northeast of the triple point with the potential for rapid supercell development. Forecast hodographs enlarge in the lowest 2-km AGL layer during the 22z-01z period, and in addition to risk for very large hail, a tornado threat may also develop. Storm coverage is expected to increase during the evening as the LLJ intensifies and into the overnight and perhaps preferentially develop along the front while growing upscale and moving east into the lower MO Valley late. A lingering hail/wind risk will probably accompany this activity. Farther south along the dryline over south-central KS to near the Red River, the leading edge of strong, westerly 80-90 kt 200-mb flow will overspread the warm sector by late afternoon, thereby elongating the hodograph. Very strong heating may lead to local erosion of the cap with one or a few updrafts becoming sustained and quickly evolving to a discrete supercell mode. A conditionally very favorable environment over OK for a giant-hail risk (diameters 3+ inches) may develop with any supercell. As this activity matures during the early evening, increasing CINH with east extent and with the onset of diurnal cooling will combine to limit the tornado risk before CINH eventually overwhelms lingering updrafts and coincides to a dissipation of the storm activity by mid evening. ...TX dryline... Model guidance currently indicates a paucity of convective potential along the dryline over parts of northwest TX southward to the Edwards Plateau. A conditionally very unstable boundary layer and deep-layer shear will support supercell potential. Any storm that manages to develop will likely pose a large-hail threat for at least an hour or two before this risk diminishes by mid evening. ..Smith.. 04/18/2023 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1136 AM CDT Tue Apr 18 2023 Valid 181700Z - 191200Z ...CRITICAL FIRE WEATHER AREA FOR MUCH OF NEW MEXICO AND THE SOUTHERN/CENTRAL HIGH PLAINS... ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF CENTRAL AND EASTERN VIRGINIA... ...Mid Atlantic... Early morning observations show clear skies and surface temperatures quickly warming into the 60s and 70s F over much of DelMarVa into southern NJ. Dry surface conditions with RH values in the low 20s were being observed along with westerly surface winds near 20 mph. Current trends lend higher confidence in widespread elevated and critical conditions developing this afternoon over mostly receptive fuels. Fire-weather concerns will likely continue into this early evening before wind slacken and humidity recovers. Otherwise, the previous forecast remains valid with no changes. ..Lyons.. 04/18/2023 .PREV DISCUSSION... /ISSUED 0116 AM CDT Tue Apr 18 2023/ ...Synopsis... A mid-level trough will approach the Plains while a second trough ejects into the Atlantic today. Surface low development is likely across the central High Plains, with a dryline poised to advance eastward across western Kansas into the Texas Panhandle. Behind the dryline, 20+ mph sustained westerly surface winds amid 15 percent RH will promote widespread Critical conditions from central New Mexico/Colorado into southwest Kansas and the Oklahoma/Texas Panhandles. Along/immediately ahead of the dryline, an isolated thunderstorm or two may develop from southwestern Kansas into northwestern Texas. Given relatively low confidence in thunderstorm initiation, isolated dry thunderstorm highlights have been withheld this outlook. Nonetheless, any storms that can develop should be high-based, and a couple of dry strikes are possible immediately after initiation before storms can mature. Across the Mid Atlantic, a corridor of dry westerly surface winds appear likely this afternoon from eastern West Virginia to the Atlantic Seaboard given the passage of a surface lee trough. Elevated highlights have been added where surface wind speeds are expected to reach 15 mph amid 20-30 percent RH for at least a few hours, and where fuels are dry enough to support wildfire-spread. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1126 AM CDT Tue Apr 18 2023 Valid 181630Z - 191200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PARTS OF THE CENTRAL STATES... ...SUMMARY... Isolated severe thunderstorms are possible from parts of the southern Great Plains northward into the Mid Missouri Valley/Upper Midwest and westward into Wyoming. Large hail and severe wind gusts will be the hazards with the stronger storms late this afternoon into tonight. ...Central/southern Great Plains to Mid-MO Valley/Upper Midwest... Modified moisture return is occurring from the southern Great Plains ahead of a deepening lee cyclone over the central High Plains. But guidance has above-average spread in the degree of this return into KS and southern NE by early evening, lowering confidence in the overall environment and sustenance of deep convection given the stout elevated mixed-layer over the moist sector. Based on 12Z observed soundings, GOES PW imagery, and 16Z surface observations, it appears that the drier spectrum of guidance is more reasonable with the magnitude of this return, suggesting mid 40s to mid 50s surface dew points north of OK by 00Z. This should be adequate to support isolated high-based thunderstorms along the dryline in the western KS vicinity during the late afternoon to early evening. This activity will pose a threat for isolated large hail and localized severe wind gusts. Still, morning HRRR runs are insistent that even this scenario will fail, with effectively no sustained deep convection along the entire dryline. During the evening, a strengthening low-level jet will yield warm theta-e advection tonight. This might support any lingering dryline storms spreading northeast towards the Mid-MO Valley or more likely the development of elevated thunderstorms where ascent can overcome the stout elevated mixed-layer. Steep mid-level lapse rates and favorable cloud-layer shear will conditionally support a few elevated supercells, although the predominant convective mode should tend towards clusters northeast of the surface warm front. Isolated large hail appears to be the main threat. ...WY to western SD/NE... An elongated upper trough over the Northwest should consolidate across the northern Great Plains tonight. This will occur as a piece of the strong mid-level jet across northern/central CA and the Sierras ejects across the central Rockies to the Black Hills vicinity. This strengthening flow regime and large-scale ascent will aid in scattered high-based, low-topped convection across WY this afternoon and spreading into western SD/NE this evening. With surface dew points only in the 20s to low 30s, buoyancy will likely remain scant. But inverted-v thermodynamic profiles will support a threat for sporadic severe wind gusts. ..Grams/Thornton.. 04/18/2023 Read more

No watches are valid as of Mon Apr 17 21:31:01 UTC 2023.

No Mesoscale Discussions are in effect as of Mon Apr 17 21:31:01 UTC 2023.

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0251 PM CDT Mon Apr 17 2023 Valid 172000Z - 181200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE SOUTHERN HIGH PLAINS... ...SUMMARY... Isolated severe wind gusts and small to marginally severe hail will be possible between 4 to 9 PM CDT across parts of west Texas and southeast New Mexico. ...Discussion... The only change made to the previous convective outlook is to remove low-severe probabilities over South FL. Convective overturning coupled with veering low-level flow --coincident with a cool front-- will combine to diminish the risk for severe thunderstorms the remainder of the afternoon. ..Smith.. 04/17/2023 .PREV DISCUSSION... /ISSUED 1123 AM CDT Mon Apr 17 2023/ ...Southeast FL... A near-term threat for a severe storm or two should persist for a couple more hours attendant to a minor southern-stream mid-level trough passing across the southern peninsula. Within a lingering combination of moderate buoyancy and deep-layer shear, weak supercells will remain capable of producing small to marginally severe hail and locally strong gusts. Low-level winds appear to be in the process of weakening and becoming more veered, which will result in a decreasing threat later this afternoon. ...West TX and southeast NM... Northwest of the more substantial moisture return, deep boundary-layer mixing will support at least isolated high-based thunderstorms along a lee trough during the late afternoon and early evening. Inverted-v thermodynamic profiles with DCAPE of 1000-1500 J/kg will favor strong to locally severe outflow gusts with semi-organized cells, based on the steep lapse rates and moderately elongated, straight hodographs. An LP-supercell with a marginal hail threat is plausible towards the Big Bend/Lower Pecos Valley owing to greater elongation of the hodograph and MLCAPE near 500 J/kg. Read more