Severe Storms

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1212 PM CDT Sat Sep 17 2022 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS CENTERED OVER CENTRAL ILLINOIS AND INTO INDIANA... ...SUMMARY... Risk for severe storms is evident across an area centered over central Illinois and into Indiana Sunday afternoon and evening. ...Synopsis... Gradual amplification of the upper flow field over the U.S. is expected to continue Sunday, as a low just off the California coast deepens as it retrogrades slowly southwestward. In response to the deepening low, riding centered over Texas is progged to expand northward across the southern Plains and into the central U.S. and the Rockies. A weak cyclonic disturbance is forecast to crest the developing ridge, crossing the northern Plains and then Upper Mississippi Valley through the day, and then pivoting east-southeastward across the Upper Great Lakes and Mid Ohio Valley overnight. At the surface, a cold front is forecast to shift across the Upper Midwest and into the Great Lakes and Mid Mississippi Valley region through the day, and should focus an area of vigorous convection over the corn belt region during the afternoon and overnight. ...Mid Mississippi and Lower Ohio Valley region... As the upper disturbance crests the ridge, and the weak cold front advances east-southeastward toward the Midwest, diurnal heating of a moist boundary layer will support moderate destabilization, with mixed-layer CAPE values peaking in the 2000 to 3000 J/kg range through late afternoon. The degree of instability in tandem with ascent focused at low levels in the vicinity of the front will support vigorous storm initiation -- likely in the southeastern Iowa/northeastern Missouri/west-central Illinois area initially. With initial storm mode expected to be isolated, and aided by strengthening/weakly veering flow with height, a few rotating storms are expected to evolve -- accompanied by all-hazards severe potential. With time, storms should tend to congeal -- likely into multiple clusters, with redevelopment of storms that move across some of the same areas possible given increasingly west-northwesterly flow aloft atop a persistent feed of high low-level theta-e air from the southwest. As this upscale growth occurs, risk for damaging winds and hail will likely be maintained into the evening, as convection spreads eastward/southeastward with time. Storms will likely spread into the Mid Ohio Valley region late, though severe potential should wane overnight as the airmass stabilizes diurnally. ..Goss.. 09/17/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1135 AM CDT Sat Sep 17 2022 Valid 171700Z - 181200Z ...NO CRITICAL AREAS... Dry and breezy conditions are ongoing across portions of the Southwest, but fuels remain moist across this region. Therefore, fire weather conditions remain minimal. Elsewhere, light winds preclude widespread fire weather concerns. See previous discussion below. ..Bentley.. 09/17/2022 .PREV DISCUSSION... /ISSUED 1259 AM CDT Sat Sep 17 2022/ ...Synopsis... A predominantly weak, zonal flow pattern across the CONUS will begin to break down throughout the day as a mid-level trough enters portions of the Pacific Northwest and northern California coast. Consequently, broad 20-25 kt southwesterly flow will overspread much of the West. At the surface, a cold front will move through portions of the Pacific Northwest. In advance of this front, diurnally driven southwesterly winds will develop, perhaps reaching sustained values of 15-20 mph, while RH values fall into the upper teens. These conditions may support a localized threat for elevated fire-weather conditions, mainly across northwest Nevada and far southeast Oregon. Otherwise, fire-weather concerns are expected remain low elsewhere across the CONUS. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1127 AM CDT Sat Sep 17 2022 Valid 171630Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS NORTHERN MN AND THE MID-MO VALLEY... ...SUMMARY... A couple tornadoes, scattered severe hail, and isolated damaging winds are possible across a portion of northern Minnesota during the late afternoon to early evening. Scattered large hail, damaging winds, and a brief tornado are also possible this evening across a portion of the Mid-Missouri Valley. ...Central to northern MN... A low-amplitude shortwave trough approaching the Upper Red River Valley will move across northern MN into northwest ON by this evening. Partial cloud breaks are evident ahead of this wave mixed with patches of persistent but thinning low-level stratus. The 12Z NAM appears overdone with MLCAPE magnitude given its depiction of mean mixing ratios from 14-15 g/kg later today when upstream 12Z observed soundings sampled only 12-13 g/kg at most. With the EML plume and attendant steep mid-level lapse rates also displaced south of this region, MLCAPE will probably only peak towards 1500 J/kg. Surface-based thunderstorm development will likely be focused in a confined corridor near the evolving frontal wave, currently over northeast SD, as it tracks east-northeast into northern MN. 12Z guidance has generally trended toward a weaker depiction of low-level mass response relative to the 00Z ECMWF, suggesting low-level hodograph curvature may remain small except along the surface warm front. Favorable elongation of the mid to upper hodograph given speed shear with height amid southwest flow should support a few discrete supercells. Severe hail will probably be the primary hazard in coverage, but a couple tornadoes are possible if activity can remain rooted where SRH is enhanced along the west/east-oriented warm front. These threats will likely diminish into late evening as activity spreads towards northeast MN. ...IA to central KS... A weakening MCS persists across southern IA and northwest MO with large-scale outflow analyzed from the I-70 corridor in northeast KS arcing to the northwest in central NE. Air mass recovery will occur across the Mid-MO Valley into this evening, but will clearly be impacted by this morning's activity, which renders uncertainty in just how intense redevelopment this evening will truly be. A hot air mass will be prevalent from the southern High Plains into central KS. Isolated high-based thunderstorms will probably develop along the dryline to triple-point intersection with a threat for isolated severe gusts and hail. More prevalent convective redevelopment will occur atop the residual outflow/differential heating zone this evening as a southwesterly low-level jet intensifies. Forecast soundings differ, but given the presence of the upstream EML and limited time for intense boundary-layer heating it appears most probable that convection will be rooted from elevated parcels, especially with time after dusk. This renders low confidence in a greater tornado threat despite low-level hodographs becoming highly enlarged. With weak changes in magnitude in winds with height above 700 mb, a cluster convective mode should dominate. This should subdue the large hail threat and the weak low-level lapse rates deeper into IA should limit the overall severe wind threat with northeast extent as well. Still with upscale growth into a slow-moving MCS and embedded organized updrafts probable this evening, will maintain a cat 2 severe risk delineation. ..Grams/Lyons.. 09/17/2022 Read more

No Mesoscale Discussions are in effect as of Fri Sep 16 17:49:02 UTC 2022.

No watches are valid as of Fri Sep 16 17:49:02 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1234 PM CDT Fri Sep 16 2022 Valid 171200Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MINNESOTA/IOWA AREA... ...SUMMARY... Isolated severe thunderstorms -- and local/all-hazards severe potential -- are expected Saturday from parts of the Upper Mississippi Valley area/Upper Midwest into/across portions of the Mid Missouri Valley. ...Synopsis... An initially low-amplitude upper flow pattern over the U.S. will gradually amplify, especially over the West. This amplification will result from a broad low from British Columbia to just off the Pacific Northwest Coast early in the day, that is expected to strengthen/consolidate as it shifts southward to just off the northern California coast late. As this occurs, ridging will begin to expand across the south-central U.S., while a belt of fast southwesterly flow in between the two features persists from the Intermountain West to the Upper Great Lakes. At the surface, the primary feature of interest will be a weak low -- forecast to evolve over the eastern South Dakota/southwestern Minnesota border area during the afternoon. A weak cool front should extend south-southwestward across eastern Nebraska and into Kansas, while the warm front extends east-northeastward across northern Minnesota. The main severe potential Saturday should reside in the vicinity of the warm sector of this system. ...Minnesota to southwestern Wisconsin/Iowa, and southwestward across northeastern Kansas... Though hindered in some areas by ongoing/remnant clouds/convection early in the period, daytime heating and low-level moist advection within the southerly flow regime will result in moderate afternoon airmass destabilization from the Upper Midwest into Kansas. As a short-wave trough crosses the Dakotas early and eventually approaches Minnesota, ascent -- focused near a weak low progged to evolve near the South Dakota/Minnesota border -- will likely result in isolated storm development by late afternoon. Farther south, focus for convective initiation appears more nebulous, without a clear low-level focusing mechanism. Still, low-level warm advection across this region should result in isolated to scattered convective development -- initially during the afternoon, with a second round of storms possible as a southerly low-level jet intensifies overnight. With 35 to 40 kt west-southwesterly mid-level flow spreading across the area with time, atop low-level southerlies, a few of the stronger storms will likely acquire rotation -- posing risk for hail and/or locally damaging wind gusts. A tornado or two may also occur -- with a favored area possibly over central/northern Minnesota near the anticipated low/warm frontal position. Storms will likely continue -- especially across the Iowa vicinity -- overnight, aided by persistent low-level warm advection, though any lingering severe potential should wane gradually through late evening. ..Goss.. 09/16/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1144 AM CDT Fri Sep 16 2022 Valid 161700Z - 171200Z ...NO CRITICAL AREAS... Some dry and breezy conditions are expected across portions of New Mexico, but fuels are very moist across the region. Therefore, fire weather concerns remain low. ..Bentley.. 09/16/2022 .PREV DISCUSSION... /ISSUED 0158 AM CDT Fri Sep 16 2022/ ...Synopsis... An upper-level shortwave trough currently over Nevada is forecast to move east-northeastward toward the central/northern Plains today. Meanwhile, another upper-level shortwave trough will move onto the Pacific Northwest coast as an upper low deepens offshore. At the surface, a lee trough will deepen over the High Plains throughout the day. Overall, the overlap of strong winds and low RH with dry fuels appears minimal across the CONUS, limiting the fire-weather concerns today. ...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 1053 AM CDT Fri Sep 16 2022 Valid 161630Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS WESTERN TO CENTRAL NEBRASKA... ...SUMMARY... Isolated to perhaps scattered severe thunderstorms are anticipated across a portion of the central Great Plains, centered on 3 to 10 PM CDT. ...Central Great Plains... A low-amplitude shortwave trough over the central Rockies will move east-northeast into the Dakotas by tomorrow morning. Large-scale ascent associated with this wave will impinge on a destabilizing downstream air mass to aid in scattered thunderstorms over the higher terrain spreading across the High Plains later this afternoon. This initial activity will be high-based, forming over weak but sufficient moisture and deep/well-mixed sub-cloud layers. Wind profiles west of the lee trough will be nearly unidirectional, limiting effective shear, despite gradually increasing mid/upper-level speeds. Scattered strong to isolated severe gusts and small to marginally severe hail will be the main hazards this afternoon amid moderate mid-level lapse rates. Thunderstorms forming on or crossing the lee trough may eventually gain greater severe potential in the early evening, as activity impinges on a more favorably moist boundary layer, currently evident in GOES PW imagery across the eastern half of NE. While the expectation is for the character of convection to be outflow-dominant/cold-pool-driven by this point, sufficient veering and strengthening of the wind profile with height will yield an elongated hodograph that would support potential for a few embedded supercells. The more probable evolution is for this to maintain persistence of a mostly isolated and marginal severe wind/hail threat after dusk into the late evening, before convective intensities subside overnight. ...Southern High Plains... Isolated thunderstorms should develop along a portion of the dryline centered on the Panhandles where surface temperatures breach 90 F. Modest mid-level lapse rates and weak buoyancy will be limiting factors to storm intensity. But 20-25 kt effective shear and steep low-level lapse rates could support locally strong gusts in the more robust storms during the late afternoon to early evening. ..Grams/Moore.. 09/16/2022 Read more

No watches are valid as of Thu Sep 15 17:43:02 UTC 2022.

No Mesoscale Discussions are in effect as of Thu Sep 15 17:43:02 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1213 PM CDT Thu Sep 15 2022 Valid 161200Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS CENTERED OVER PORTIONS OF WESTERN AND CENTRAL NEBRASKA... ...SUMMARY... Severe thunderstorms are possible across portions of the central High Plains and central Plains on Friday. ...Synopsis... Broad/low-amplitude cyclonic flow will persist across the western and north-central U.S. Friday, while cyclonic flow also persists across the Northeast. In between, weak ridging will prevail from the Great Lakes to the Gulf of Mexico. Weak short-wave disturbances/cyclonic vorticity maxima will progress east-northeastward across the Rockies and central U.S. with time, embedded within the weakly cyclonic west-southwesterlies. At the surface, high pressure will prevail over most of the eastern half of the country. Lee troughing is expected across the High Plains vicinity, with weak cyclogenesis expected across the eastern Wyoming vicinity as one of the aforementioned vorticity maxima shifts across this region during the afternoon and evening hours. ...Eastern Wyoming/northeastern Colorado east-southeastward to eastern Nebraska... As a weak lee low/trough strengthens a bit with time, the combination of increasing ascent, and afternoon heating/destabilization, should support storm development over the central High Plains. Initial convection should evolve over portions of eastern Wyoming and northeastern Colorado, in an isolated/cellular manner. Given low-level southeasterlies beneath moderate mid-level west-southwesterlies, shear will likely prove sufficient for multicell/local supercell organization, and attendant risk for hail and/or damaging wind gusts with the stronger updrafts. As storms shift eastward with time toward lower elevations through late afternoon/early evening, greater instability anticipated with eastward extent may support upscale/linear growth. Models continue to suggest evolution of an at least loosely organized convective band, that would shift across parts of southern South Dakota and Nebraska with time. While surface wind-gust potential will likely become more hindered with time as the boundary layer cools/stabilizes through the evening, it appears at this time that potential warrants upgrade to a small SLGT risk/15% wind probability, centered from the Nebraska Panhandle into central portions of the state for the late afternoon/early-evening time period. ..Goss.. 09/15/2022 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1113 AM CDT Thu Sep 15 2022 Valid 151630Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL AND SOUTHERN PLAINS.... ...SUMMARY... Isolated severe-thunderstorm gusts are possible this afternoon/early evening across portions of the central Plains and southern High Plains. ...Central and Southern Plains... A broad but weak upper trough will persist across the Rockies and western states today, with a shortwave trough apparent on WV approaching eastern CO/western KS. This will result in relatively cool temperatures aloft and moderately steep mid-level lapse rates over much of the central and southern Plains today, along with a corridor of around 1000 J/kg of afternoon MLCAPE. A consensus of 12z CAM solutions show multiple clusters of thunderstorms from west TX northward into parts of KS/NE/SD this afternoon. Forecast soundings show rather weak mid-level winds, which should limit the degree of convective organization. However, steep low-level lapse rates and merging outflows will lead to localized gusty winds in the strongest clusters. ..Hart/Lyons.. 09/15/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1039 AM CDT Thu Sep 15 2022 Valid 151700Z - 161200Z ...NO CRITICAL AREAS... The previous forecast (see below) remains on track. ..Squitieri.. 09/15/2022 .PREV DISCUSSION... /ISSUED 1222 AM CDT Thu Sep 15 2022/ ...Synopsis... Large-scale troughing and enhanced west-southwesterly midlevel flow will persist across the western CONUS, while a few embedded shortwave impulses overspread the north-central Rockies. At the surface, lee troughing accompanied by a tight pressure gradient will persist over the Plains. This pattern will once again favor breezy/gusty southerly surface winds across most of the Plains, though sufficient boundary-layer moisture should limit any substantial RH reductions. Given the marginal RH and ongoing precipitation over modestly receptive fuels, Elevated highlights have been withheld despite the breezy/gusty surface winds. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Wed Sep 14 17:59:02 UTC 2022.

No Mesoscale Discussions are in effect as of Wed Sep 14 17:59:02 UTC 2022.

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1240 PM CDT Wed Sep 14 2022 Valid 151200Z - 161200Z ...NO CRITICAL AREAS... The previous forecast remains on track, with no changes or additions made. Please see the previous forecast below for more details. ..Squitieri.. 09/14/2022 .PREV DISCUSSION... /ISSUED 0139 AM CDT Wed Sep 14 2022/ ...Synopsis... Broad midlevel troughing and moderate west-southwesterly flow aloft will persist over the western CONUS, supporting the maintenance of a surface lee trough over the Plains. Breezy southerly surface winds will continue to affect the central and southern Plains owing to a tight pressure gradient peripheral to the lee trough, though sufficient boundary-layer moisture and cloud coverage should temper RH reductions. The marginal RH and continued shower/thunderstorm development should generally limit fire-weather concerns despite the breezy/gusty surface winds. ...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 1220 PM CDT Wed Sep 14 2022 Valid 151200Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTHERN AND CENTRAL PLAINS... ...SUMMARY... Isolated to widely scattered high-based storms capable of damaging wind gusts are possible from the Texas Panhandle, to central Kansas, and into central/eastern Nebraska Thursday. ...Southern and central Plains... Broad troughing across the western US is forecast to continue through Thursday as high pressure shifts eastward. Embedded within the broader trough, a subtle shortwave is expected to move over the southern and central Plains Thursday afternoon and evening. Trailing from a weak surface low across the Dakotas, a lee trough/low will support increasing southerly flow across much of the Plains. Modest moisture return (surface dewpoints in the 50s to low 60s F) will filter westward toward the surface boundary where plentiful diurnal heating is expected. Storms will be possible along the entire corridor from NE into the TX Panhandle, though there remains some uncertainty on convective coverage given the subtle forcing for ascent. Current hi-res guidance suggests the greatest storm coverage will remain closer to the surface low across central and eastern NE, where low-level flow is expected to be locally stronger. By early to mid afternoon, convective development along the length of the lee trough is expected. With only modest surface moisture return forecast, regional model soundings show weak buoyancy profiles generally less than 1000 J/kg of MLCAPE. Modest flow aloft associated with the shortwave trough should also limit effective shear to 20-25 kt. Storm organization potential will likely remain localized and tied to consolidating outflow/clustering of any multi-cell storms that persist. Should this occur, a well-mixed boundary layer with steep low-level lapse rates and LCLs near 2 km may support an isolated risk for damaging outflow winds given the potential for stronger downdrafts. ...Rest of US... Scattered to numerous thunderstorms are also anticipated across the FL Peninsula, as a moist low-level airmass interacts with a weak stationary front across the region. Weak vertical shear will keep storms unorganized with only locally stronger wind gusts expected. Isolated to scattered thunderstorms are also expected across the northern Rockies and Great Basin, ahead of a low-amplitude shortwave trough over the western CONUS. Limited buoyancy and shear should preclude severe storms. ..Lyons/Jewell.. 09/14/2022 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1053 AM CDT Wed Sep 14 2022 Valid 141630Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING OVER PORTIONS OF THE SOUTHERN HIGH PLAINS... ...SUMMARY... Storms capable of isolated severe gusts will be possible this afternoon and evening over portions of the southern High Plains. ...Southern High Plains... A weak/broad trough is present today over the western US, with weak but cyclonic flow across the southern High Plains. Strong heating over the higher terrain of eastern NM will lead to scattered thunderstorms by late afternoon, spreading slowly eastward into west TX. Winds aloft are rather weak, but steep low-level lapse rates and CAM solutions of growing clusters of storms may result in localized gusty/damaging winds for a few hours this evening. ..Hart/Moore.. 09/14/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1050 AM CDT Wed Sep 14 2022 Valid 141700Z - 151200Z ...NO CRITICAL AREAS... The previous forecast remains on track. The latest guidance consensus suggests that a couple of hours of widespread Elevated conditions may occur across western Nebraska into far northwest Kansas. However, clouds and occasional showers will continue to overspread the central Plains through the day, with potentially heavier rains possible through Day 2/tomorrow. As such, significant wildfire-spread potential should be somewhat limited, precluding the addition of any fire weather highlights. ..Squitieri.. 09/14/2022 .PREV DISCUSSION... /ISSUED 0138 AM CDT Wed Sep 14 2022/ ...Synopsis... A large-scale ridge will remain centered over the MS Valley, while broad midlevel troughing and enhanced west-southwesterly flow aloft persist over the western states. Embedded within the west-southwesterly flow, a series of low-amplitude shortwave troughs will cross the Rockies, reinforcing a surface lee trough over the northern and central High Plains. ...Central High Plains... Southerly surface winds will strengthen across the Plains in response to the deepening lee trough. At the same time, increasing boundary-layer moisture and scattered to broken mid/high-level clouds may limit RH reductions where the breezy winds are expected. Despite the marginal RH reductions, 20-25 mph sustained southerly surface winds (with 30-35 mph gusts) could yield locally elevated fire-weather conditions during the late morning/early afternoon hours. This will especially be the case over parts of northeast CO, northwest KS, and southwest NE -- where pockets of 25 percent minimum RH will be possible prior to the development of showers and storms. With that said, the aforementioned cloud coverage, widely scattered showers and storms, and marginal fuels cast uncertainty on the overall fire-weather threat -- precluding Elevated highlights at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Tue Sep 13 18:01:02 UTC 2022.