Severe Storms

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0744 AM CDT Sat May 14 2022 Valid 141300Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FROM THE GREAT LAKES TO THE LOWER MS VALLEY...AND THIS AFTERNOON INTO TONIGHT FOR PARTS OF WEST TX TO SOUTHEAST NE/NORTHEAST KS... ...SUMMARY... Strong to locally severe thunderstorms are possible across parts of the Great Plains, Mississippi Valley, and Great Lakes regions, mainly this afternoon and evening. Isolated hail and damaging wind gusts will be the primary threats. Some threat may redevelop late tonight across parts of Nebraska and Kansas. ...Synopsis... The persistent midlevel low over the Southeast is in the process of evolving into more of an open wave, and a primary embedded shortwave trough will eject north-northeastward from NC to southern New England by early Sunday. This pattern evolution will be in response to gradual upstream height falls across the upper Midwest and upper MS Valley, downstream from modest height rises over the northern Great Basin and northern Rockies. Within the primary jet, an embedded shortwave trough over MN/WI will eject northeastward toward ON, and an upstream shortwave trough over the northern High Plains will amplify some while digging southeastward over the middle MO Valley. The surface synoptic boundaries will remain rather diffuse today into early tonight, prior to some sharpening of a front near the KS/NE border by the end of the period. ...West TX to western KS this afternoon/evening... A somewhat diffuse dryline is expected this afternoon from western KS southward into west TX, where surface heating and deep mixing could allow isolated thunderstorm development by mid-late afternoon. A high-based supercell or two with isolated large hail and strong-severe outflow gusts will be possible, given sufficiently long hodographs with effective bulk shear greater than 40 kt. ...Lower MS Valley to the Great Lakes this afternoon/evening... Deep-layer flow/shear will be very weak from the lower OH River into MI, where surface heating will drive MLCAPE of 1000-2000 J/kg (weaker north) and DCAPE near 1000 J/kg. Weak low-level convergence and minimal convective inhibition should support widely-scattered to scattered thunderstorm development by mid-late afternoon, with the potential for isolated wind damage with downbursts. Somewhat richer low-level moisture and larger CAPE are expected farther south into the lower MS Valley region, though there is some uncertainty regarding the lingering influence of ongoing morning convection across the Ark-La-Miss. Where pockets of stronger surface heating occur, especially in conjunction with lingering outflow boundaries, a few multicell clusters with strong/isolated damaging downburst winds will be possible. ...Southeast NE/northeast KS 06-12z Sunday... The aforementioned shortwave trough and low-level frontogenesis, interacting with steep midlevel lapse rates and MUCAPE near 1500 J/kg, will likely result in the formation of elevated thunderstorm clusters early Sunday morning. This convection will pose mainly an isolated large hail threat during this forecast period, before evolving into more of a damaging wind threat during the day Sunday (D2). ..Thompson.. 05/14/2022 Read more

No watches are valid as of Fri May 13 14:02:02 UTC 2022.

No Mesoscale Discussions are in effect as of Fri May 13 14:02:02 UTC 2022.

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook RESENT 1 NWS Storm Prediction Center Norman OK 0816 AM CDT Fri May 13 2022 Valid 131300Z - 141200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO EARLY TONIGHT FROM CENTRAL OK INTO MO... ...SUMMARY... Scattered afternoon and evening thunderstorms are expected Friday from the Upper Great Lakes to the southern Great Plains. The stronger storms will be capable of damaging gusts and hail. ...Upper MS Valley to the southern Plains through early tonight... Only small changes to the large-scale pattern are expected through early Saturday, as a weakening midlevel low will persist over the Southeast, and the primary belt of westerlies aloft will remain from the Pacific Northwest to the northern Plains/upper MS Valley. In the wake of an embedded shortwave trough and occluding cyclone moving north-northeastward to southern MB and western ON, a trailing cold front will make slow southeastward progress from WI to MO and OK. Despite some low-level drying the past few days as a result of retrogression of the Southeast midlevel low, boundary-layer dewpoints remain mostly in the mid 60s ahead of the slow-moving cold front and residual outflow boundaries. The corridor of richer pre-frontal moisture will be narrowest to the north toward WI, and somewhat broader to the south toward MO and OK. Overnight/morning convection raises some uncertainty in the forecast for this afternoon/evening. It appears some of the convection may persist long enough from northeast OK to northwest MO to influence later storm development through the stabilizing effects of lingering clouds into the afternoon. Any persistent differential heating zones and/or convective outflows could also serve to focus afternoon storm development. With MLCAPE near 3000 J/kg expected and modest vertical shear, a mix of multicell clusters and some supercells will be possible later this afternoon into early tonight from OK into MO. Occasional damaging gusts and isolated large hail will be the main threats. The window of opportunity for severe storms toward WI will be smaller and more marginal, given relatively weak vertical shear and weaker buoyancy in a narrower corridor compared to the MO-OK area. Farther southwest in TX, aside from isolated morning storms, deep mixing with strong surface heating should support at least isolated thunderstorm development later this afternoon along and immediately east of a remnant dryline/front. Inverted-V profiles will support high-based storms with the threat of strong downburst winds. Mid-upper westerly flow and straight hodographs could be sufficient for some splitting supercells with isolated large hail. ...Lower MS Valley this afternoon/evening... Along a diffuse front near the MS River and beneath modest (20-25 kt) northerly flow aloft, daytime heating and boundary-layer dewpoints in the 68-70 F range will contribute to MLCAPE of 2500-3000 J/kg. Scattered thunderstorm development is expected along the diffuse front by mid afternoon, and multicell clusters will subsequently spread southward across the Ark-La-Miss through this evening. Vertical shear will be relatively weak, but midlevel lapse rates/buoyancy will be sufficiently large to support marginally severe hail. Steep low-level lapse rates, DCAPE near 1000 J/kg, and precipitation loading suggest that strong outflow gusts will be the main concern. ..Thompson.. 05/13/2022 Read more

No watches are valid as of Thu May 12 14:46:01 UTC 2022.

No Mesoscale Discussions are in effect as of Thu May 12 14:46:01 UTC 2022.

Public Severe Weather Outlook
PUBLIC SEVERE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0758 AM CDT THU MAY 12 2022 ...Severe thunderstorms expected over parts of the northern/central Plains into the Upper Midwest this afternoon and evening... * LOCATIONS... Western Minnesota Eastern South Dakota Southeastern North Dakota * HAZARDS... Widespread damaging winds, some hurricane force A few tornadoes Scattered large hail, some baseball size * SUMMARY... Severe thunderstorm gusts (some near 75 mph), large hail and a few tornadoes are expected today over parts of the eastern Dakotas, eastern Nebraska, western Iowa, and central/southern Minnesota. Preparedness actions... Review your severe weather safety procedures for the possibility of dangerous weather today. Stay tuned to NOAA Weather Radio, weather.gov, or other media for watches and warnings. A watch means that conditions are favorable for severe thunderstorms over the next several hours. If a severe thunderstorm warning is issued for your area, move to a place of safety, ideally in an interior room on the lowest floor of a sturdy building. && ..Gleason.. 05/12/2022 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0753 AM CDT Thu May 12 2022 Valid 121300Z - 131200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF EASTERN SOUTH DAKOTA...PARTS OF WESTERN MINNESOTA AND SOUTHEASTERN NORTH DAKOTA... ...SUMMARY... Severe thunderstorm gusts (some near 75 mph), large hail and a few tornadoes are expected today over parts of the eastern Dakotas, eastern Nebraska, western Iowa, and central/southern Minnesota. ...Synopsis... The mid/upper-level pattern will feature mean troughing over the western CONUS, a lengthy but weakening ridge from west-central MX across the Arklatex to southern ON, and a broad/retrograding Atlantic cyclone, forecast to move westward and ashore over much of the southeastern Atlantic Coast overnight. Within the southwest- flow field preceding the western larger-scale trough, an intense shortwave trough is apparent in moisture-channel imagery from near the ID/WY border across eastern UT. This perturbation, with a negative tilt and embedded low apparent near the southwest corner of WY -- is expected to eject northeastward through the period, reaching southeastern MT, western SD and the NE Panhandle by 00Z. By 12Z tomorrow, a well-defined 500-mb low should be apparent near the ND/SK/MB border confluence, with trough southeastward over southeastern SD. The 11Z surface analysis depicted a surface low over southwestern NE, with cold front across northern CO, and warm front over southeastern SD, extreme southern MN, and southern WI. The low should move northeastward to a frontal triple point over northeastern SD by 00Z, with an occluded low developing farther northwest and near the mid/upper cyclone center over northwestern SD/southwestern ND. By then, the warm front -- likely reinforced by outflow from earlier/morning convection to its north -- should extend from the triple point across southeastern ND, north-central MN, northern WI and the western U.P. of MI. The cold front should extend across eastern SD (likely behind a line of convection), south-central NE, western KS, and southeastern CO. A dryline will intersect the front over west-central KS, extending south-southwestward over the eastern TX Panhandle, the Permian Basin and the Big Bend region with isolated strong-severe convection possible late this afternoon. By 12Z, the triple-point low should lose definition, as the western low deepens and becomes nearly stacked with its midlevel counterpart. The cold front should extend across northern, central and southwestern MN, northwestern IA, southeastern NE, central KS, northwestern OK, the southern TX Panhandle, and southeastern NM. ...North-central Plains/Upper Midwest... Scattered to numerous thunderstorms are expected to develop in an arc near the surface low and cold front by mid/late afternoon, from eastern SD across central/eastern NE and into at least northern KS. A brief interval, early in the convective cycle, may support discrete to semi-discrete supercells before the convection becomes quasi-linear, and that accounts for potential for significant-severe hail in western parts of the outlook area. However, the most common severe type should evolve quickly to thunderstorm gusts -- some of which may be significant (65+ kt) strength, especially from parts of eastern SD and southeastern ND into western MN. The addition of the significant-wind area technically triggers a "moderate" categorical level, though the overall scenario hasn't changed in a major way from that discussed in the previous outlook. A few tornadoes also are possible -- especially near the surface warm front, where large buoyancy, backed near-surface winds and enlarged hodographs/SRH will yield the most favorable parameter space. The main uncertainty regarding the density and intensity of the tornado threat involves convective mode, which may be largely to entirely quasi-linear by the time activity encounters the largest combination of low-level buoyancy/shear with surface-based inflow parcels. The warm sector is forecast to destabilize throughout the day, with a combination of at least weak large-scale ascent (increasing northward), diurnal heating and related lift from below, and ultimately frontal convergence, eliminating a basal EML inversion and supporting convection initiation. Activity is expected to intensify quickly as it impinges on a narrow but very favorable prefrontal corridor where 60s to near 70 F surface dewpoints contribute to MLCAPE in the 3500-4500 J/kg range in and near the "moderate" area, decreasing gradually with southward extent as more low-level moisture is mixed out. Low-level and deep shear will be greatest near the triple point and warm front, with 300-500 J/kg effective SRH and 45-55-kt effective-shear magnitudes, also decreasing southward toward KS. A substantial component of mid/upper winds parallel to the axis of convective forcing indicates potential for fairly fast merging of early discrete and sporadically supercellular convection, forming a QLCS. Surges of wind from resulting LEWP/bowing segments will pose the greatest overall severe hazard, with line-embedded mesovortices and perhaps a few associated tornadoes also possible. With the warm sector's not being very broad, the convective event should diminish late this evening into early overnight hours as it outruns the most favorable instability. ...Central/southern MS and vicinity... Widely scattered thunderstorms should develop this afternoon into early evening, in a moist, well-heated and weakly capped environment, along and west of a nearly north-south low-level baroclinic zone separating the lower-theta-e air related to the cyclone from the ambient Gulf warm sector. Activity should move generally southwestward, offering isolated severe downbursts. As the mid/upper low moves toward the Atlantic Coast, and associated cyclonic flow spreads across more of the Southeast, a channel of enhanced northeast flow aloft (40-50 kt at 500 mb, 75-85 kt at 250 mb) will shift slowly westward across GA/AL. While the outlook area will be off the western rim of the strongest flow aloft, increasing winds are expected to support seasonally fast southwestward movement of multicellular clusters forming on the boundary and in the nearby warm sector. MLCAPE of 1500-2000 J/kg (locally higher) should develop atop a well-mixed boundary layer supporting downdraft- acceleration potential and strong/isolated severe gusts. ..Edwards/Gleason.. 05/12/2022 Read more

No watches are valid as of Wed May 11 14:56:01 UTC 2022.

MD 0720 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR CENTRAL AND WESTERN LOWER MICHIGAN
Mesoscale Discussion 0720 NWS Storm Prediction Center Norman OK 0954 AM CDT Wed May 11 2022 Areas affected...central and western Lower Michigan Concerning...Severe potential...Watch unlikely Valid 111454Z - 111730Z Probability of Watch Issuance...20 percent SUMMARY...A cluster of storms may persist today, with marginal wind or hail threat from central into southwest Lower Michigan. DISCUSSION...A cluster of storms is propagating slowly southward across central Lower MI, within the MLCAPE cape gradient and beneath the upper ridge. While shear will remain weak today, boundary-layer heating may aid continued redevelopment of updrafts along the south/southwestern flank of this cluster. Periodic strong cores with marginal hail may occur as midlevel lapse rates are steep, with isolated strong to severe gusts as well. ..Jewell/Mosier.. 05/11/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DTX...APX...GRR... LAT...LON 43758432 42788446 42118484 42078614 42428618 42998613 43578576 43768562 43918536 43948501 43828458 43758432 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 0831 AM CDT Wed May 11 2022 Valid 111300Z - 121200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF CENTRAL/SOUTHERN MINNESOTA AND SURROUNDING STATES... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE SOUTHERN HIGH PLAINS...AND SURROUNDING THE ENHANCED RISK IN THE UPPER MIDWEST... CORRECTED FOR INCORRECT WIND PROBABILITY LINE ...SUMMARY... Severe thunderstorms are expected this afternoon/evening over the north-central states. Very large hail, wind, and a threat for tornadoes is expected. Additionally, widely scattered severe thunderstorms are anticipated across the southern High Plains. Wind/hail are the primary threats. ...Synopsis... The large-scale mid/upper-level pattern will continue to feature mean troughing over western North America, a lengthy and positively tilted ridge from west of the central MX Pacific Coast across the Arklatex to the St. Lawrence Valley, and a retrograding/cutoff synoptic-scale cyclone offshore from the Carolinas and GA. For this period, the two most convectively crucial features aloft will be ejecting northeastward from or ahead of the mean trough, in southwesterly flow: 1. A strong shortwave trough -- now including a compact closed cyclone over the Sierra of northern CA and NV. This feature will pivot slowly eastward over the Great Basin today, then turn northeastward tonight, reaching the Star Valley area of western WY and south-southeastward near the CO/UT line by 12Z tomorrow. 2. A former southern-stream shortwave trough that ejected northeastward out of northwestern MX yesterday, with convectively induced vorticity supplementation last night into early this morning over the southern High Plains. A primary/embedded MCV is evident in satellite and especially composited radar-reflectivity animations over west-central/southwestern KS, with a vorticity lobe and lesser MCV(s) across western OK. This perturbation, as a whole, will move northeastward across the central Plains this morning, reaching southwestern MN, western IA and northeastern KS by 00Z. The trough should reach Lake Superior and western Upper MI by the end of the period. At the surface, 11Z analysis showed a low over southeastern CO near the KS line, with wavy warm front northeastward across northeastern KS, south-central/eastern NE, central IA, and southern WI. A dryline was drawn from the low across the northwestern TX Panhandle, southeastern NM and far west TX, and this boundary should move little today before retreating deeper into NM overnight. The low should merge with another initially drawn over southeastern WY, then migrate erratically around northeastern CO, extreme southeastern WY and the southwestern NE Panhandle through 06Z, before moving northeastward to the western Sandhills by 12Z. The warm front should move northward through the remainder of eastern NE and IA, and into eastern SD, southern/central MN and western/southern WI by 00Z. This boundary then should decelerate over northeastern SD and central MN before being overtaken by convection. ...Upper Midwest... See SPC mesoscale discussion 719 for near-term coverage of isolated/elevated convection with hail risk over southeastern SD. Otherwise, scattered thunderstorms are expected to develop mainly this afternoon, in an arc, over southwestern parts of the outlook area, and move northward to northeastward, offering all severe hazards, including at least a few tornadoes and some large to very large hail. Early-stage supercells are expected, with evolution to an MCS over parts of southern/central MN late this afternoon into this evening. As the upscale growth occurs, the hail hazard will diminish (especially in magnitude), while the wind threat increases and becomes more dense. The severe threat will increase with time and northward extent this afternoon across eastern NE, western IA, the Siouxland area, and southwestern MN as the MCV and its accompanying wind/UVV fields impinge on a very moist, well-heated, increasingly weakly capped boundary layer, along and south of the warm front. Accompanying the ejecting shortwave trough/MCV will be mesoscale midlevel speed maxima -- roughly 55-65 kt at 500 mb and 55-65 kt at 700 mb, as evident in regional VWP and reasonably progged by models that resolve the perturbation best. These features should contribute to a corridor of enhanced vertical shear, both directly via strengthening/veering wind profiles with height, and through low-level mass response along the warm front and nearby warm sector. As these winds shift into the convective transition regime, they may enhance the damaging-gust threat with the upscale clustering across southern/central MN as well, near and south of the warm front where large CAPE still will remain available to storm inflow. Supercellular tornadoes will be possible in the warm sector, where LCLs may be lower than forecast by RAP-based models that tend to overmix a bit. However, this threat is more probable close to the warm front for any relatively discrete cells and/or QLCS segments that can interact with the front's backed flow, larger hodographs and enhanced low-level vorticity. Surface dew points in the upper 60s to low 70s F will support MLCAPE in the 3500-4000 J/kg range along and south of the warm front, with 40-50-kt effective-shear magnitudes and 200-400 J/kg effective SRH. The transition toward more-clustered convective mode should occur as flow aloft backs in response to the passing perturbation, becoming less orthogonal to the orientation of the axis of convective lift. The resulting MCS should have the potential for downward momentum transfer from strong midlevel flow, while being maintained by forced ascent of very moist inflow air along and south of the warm front. Activity should diminish overnight farther east across parts of central/northern WI and perhaps western Upper MI as inflow-layer instability gets weaker. ...Southern High Plains... Widely scattered to scattered thunderstorms are forecast to develop this afternoon near the dryline, with large hail expected. The potential also exists for a few smaller-scale clusters to evolve upscale for a few hours and offer localized concentrations of damaging gusts. Initiation and maturation of this convection should be strongly tied to diurnal heating/lift processes, and should diminish after about 03Z as the boundary layer stabilizes downshear from the convection. Strong boundary-layer heating/mixing, and resultant presence of steep low-level lapse rates and favorable DCAPE, will support maintenance of hail and acceleration of downdrafts to ground. Peak/preconvective MLCAPE in the 1000-1500 J/kg range will be attained beneath modest mid/upper-level flow, but amidst enough veering with height in the wind profile to support 30-35-kt effective-shear magnitudes. Mostly multicells, with some transient supercellular structures, are possible, also supporting the threat for large hail. ...WY/MT/western to central Dakotas... Isolated to widely scattered thunderstorms are possible late this afternoon into evening, beginning over areas of modest but sustained upslope lift in northeastern WY, and spreading/developing northeastward in sporadic fashion, potentially as far northeast as the western/central ND/SD border region overnight. The main threats will be isolated large hail and strong/briefly severe gusts. Large-scale ascent will increase this evening and overnight across the region, as the strong shortwave trough pivots out of the Great Basin and approaches. This will destabilize midlevels, and by extension with an improved warm-advection response, low levels as well. Areas of surface heating/mixing may permit surface-based development late this afternoon over northeastern WY north/northwest of the surface low, with additional/elevated initiation probable thereafter. Though buoyancy will be meager (MUCAPE generally 300-800 J/kg), favorable deep shear (effective-shear magnitudes around 50-65 kt) will favor supercell potential. Any late-developing activity overnight near the SD/ND line will have access to somewhat richer low-level moisture, in an elevated warm-advection plume extending westward from the regime related to the ENH outlook described above. Elevated MUCAPE may reach 1500-2500 J/kg amidst 50-60-kt effective-shear magnitude, suggesting a large-hail threat, conditionally risking significant-severe (2+ inches) hail in any sustained activity. Convective coverage concerns and elevated-initiation uncertainties preclude an upgrade for that region at this time. ..Edwards/Gleason.. 05/11/2022 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 0848 AM CDT Tue May 10 2022 Valid 101300Z - 111200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF NORTHWEST TEXAS AND SOUTHWESTERN OKLAHOMA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE ENHANCED AREA OVER THE SOUTHERN HIGH PLAINS...AND OVER PARTS OF WISCONSIN AND SOUTHERN UPPER MICHIGAN... CORRECTED FOR REMOVAL OF DOUBLED OUTLOOK LINES ...SUMMARY... Severe thunderstorm winds will be a hazard over parts of the southern High Plains today into this evening, along with isolated hail. Very large hail, isolated severe gusts and a tornado threat will develop this afternoon over parts of Wisconsin and vicinity. ...Synopsis... Little change is expected through this period in the highly amplified, positively tilted, mid/upper-level pattern across the CONUS. Mean troughing will persist from northern Canada, west of Hudson Bay, across the U.S. Northwest and CA. A broad, intermittently closed cyclone -- initially located over parts of northern CA, western OR and adjoining Pacific waters -- is expected to move slowly southeastward, its 500-mb low reaching central CA near FAT by 12Z tomorrow. As that occurs, height rises are expected over the northern Plains and Upper Midwest. A southern-stream perturbation is evident in moisture-channel imagery over western Chihuahua and parts of Sinaloa in northwestern MX. This feature will move northeastward today, reaching parts of far west TX and NM, the proceed to the southern High Plains by the end of the period. Elsewhere, a large, long-lasting, cut-off synoptic cyclone east of the Carolinas will begin to retrograde southwestward today, while its center remains well offshore. A very long ridge will persist from central MX across the Arklatex, lower Ohio Valley, southern ON, and southern QC. The 11Z surface analysis showed a low over north-central KS between HYS-CNK, with a warm to quasistationary front northeastward to a weak low and outflow-boundary intersection over southwestern WI. The outflow boundary extended eastward from there across southern Lake Michigan, and should retreat northward over southern/central WI today while becoming more poorly defined. Farther north, the front was drawn north-northeastward from southwestern WI across western Upper MI, and should move little through most of the day before settling southward tonight. A weak cold to stationary front trailed from the KS low across the northern TX Panhandle to southeastern CO, and should move little through the period. The dryline intersected that front near P28, and extended across the western OK/TX border region, to near LBB, FST and the Big Bend region. The dryline may retreat somewhat westward/northwestward across the Panhandle, South Plains and Permian Basin today. ...Southern High Plains... Highly variable thunderstorm coverage (from isolated to numerous) is possible in the outlook area today. The most probable area for a relatively dense concentration of convection should begin with early/organizing stages this afternoon over the South Plains/southern Panhandle/Permian Basin area. Activity then should aggregate upscale and move eastward to northeastward off the Caprock, then and across parts of northwest TX and southwestern OK this evening. Severe wind -- with at least isolated downdrafts potentially reaching 65-kt significant criteria, should accompany this activity. Despite a lack of stronger flow aloft, thermodynamically supported potential exists for cold-pool mergers and forward propagation to drive severe-thunderstorm clusters eastward into a slowly stabilizing nocturnal boundary layer over more of northwest TX and western OK this evening, before activity weakens with continued inflow-layer stabilization. Initiation will be supported by a combination of dryline lift, intense surface heating and related MLCINH removal along/east of the dryline, steep low/middle-level lapse rates ahead of the ejecting MX perturbation, and favorable low-level moisture. Surface dew points ranging from the mid 50s F just east of the dryline, to the mid-60s east of the Caprock, will support MLCAPE commonly 3000-4000 J/kg, atop a deep, well-mixed subcloud layer supporting around 1500 J/kg DCAPE. Modest mid/upper winds and related lack of more-robust vertical shear will keep activity predominantly multicellular in mode, though large hail may be noted, mainly in earlier stages of the convective process while convection is still rather discrete. ...WI and vicinity... Scattered thunderstorms are expected to develop this afternoon across western/northern parts of the outlook area and move roughly eastward into an increasingly favorable environment for supercells, with severe hail (some of it very large/damaging at 2+ inches diameter), a tornado threat, and sporadic damaging gusts. Amidst ambient, weak height rises, large-scale support aloft will be minimal at most. However, that should be more than offset for the purpose of severe potential by moderately to strongly unstable thermodynamic profiles, weak capping, boundaries, and favorable deep shear. As the outflow boundary retreats northward today and diffuses, a combination of diurnal heating and most advection will contribute to substantial low-level destabilization, with surface dew points increasing to the mid/upper 60s at least into southern/central WI. This will support peak/preconvective MLCAPE increasing into the 2500-4000 J/kg range over southern and central WI, diminishing northward into southern Upper MI. Forecast orientation and strength of deep-shear vectors suggests convection can maintain discrete to semi-discrete modes well into maturation, with supercell potential in the thermodynamically favorably modified outflow environment. Two-dimensional hail models applied to forecast soundings reasonably suggest any supercells over the region could produce very large and damaging hail. Considerable uncertainty, and inconsistency in guidance, remains as to the potential for upscale growth of convection across the region, and the potential for any such activity to coalesce cold pools enough to transition to a forward-propagational complex. Should that occur, severe potential may extend across Lake Michigan into western Lower MI and/or northern IL, aside from any isolated convection that may develop over those areas during the daytime. ..Edwards/Gleason.. 05/10/2022 Read more

No watches are valid as of Tue May 10 13:53:01 UTC 2022.

No Mesoscale Discussions are in effect as of Tue May 10 13:53:02 UTC 2022.

No Mesoscale Discussions are in effect as of Mon May 9 15:16:10 UTC 2022.

WW 0193 Status Updates
STATUS FOR WATCH 0193 HAS NOT BEEN ISSUED YET Read more

WW 193 SEVERE TSTM MN WI 091425Z - 092000Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 193 NWS Storm Prediction Center Norman OK 925 AM CDT Mon May 9 2022 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Far East-Central Minnesota Northwest Wisconsin * Effective this Monday morning and afternoon from 925 AM until 300 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 70 mph possible SUMMARY...A cluster of strong to severe thunderstorms is currently moving east across east-central Minnesota. These storms should continue moving into northwest Wisconsin within the next hour or so, with at least some threat for large hail. The severe thunderstorm watch area is approximately along and 40 statute miles east and west of a line from 30 miles west southwest of Eau Claire WI to 75 miles north of Eau Claire WI. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU3). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...CONTINUE...WW 192... AVIATION...A few severe thunderstorms with hail surface and aloft to 2 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 24045. ...Mosier/Guyer Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0755 AM CDT Mon May 09 2022 Valid 091300Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER THE UPPER MISSISSIPPI VALLEY REGION... ...SUMMARY... Large hail, damaging gusts, and a few tornadoes are all possible over the upper Mississippi Valley region today into this evening. ...Synopsis... The basic mid/upper-level pattern through the period will feature a positively tilted mean trough over western parts of Canada and the CONUS, with numerous embedded shortwaves/vorticity maxima. Meanwhile, an already high-amplitude downstream ridge -- now extending from central MX across the Arklatex, lower Ohio Valley, southern ON, and southern QC -- will amplify further, while moving little. A long-lived synoptic cyclone will remain over Atlantic waters east of the Carolinas. The southwest-flow belt downstream from the western mean trough will cover most of the Rockies, Great Plains, mid/upper Mississippi Valley, and Upper Midwest. An embedded/leading shortwave trough with convective vorticity augmentation -- now apparent in moisture-channel imagery and composited radar fields over SD -- will eject northeastward across ND and northern MN today. By 00Z, a closed 500-mb low should develop along the shortwave trough, over southern MB, with the trough extending southeastward to northern MN. The perturbation will eject northeastward over MB and northwesternmost ON tonight, leaving behind rising heights across the central/northern Plains and Upper Midwest. At the surface, 11Z analysis showed a low over northern NE near ONL, with cold front southwestward across northwestern KS, becoming quasistationary over east-central CO. A warm front was drawn southeastward across eastern NE, northeastern KS, southwestern MO, and eastern AR. A dryline intersected the cold front over southern NE, and extended southward to western OK, then south-southwestward across the TX Permian Basin. That low is expected to move north-northeastward across southeastern MB by 00Z, with cold front trailing through eastern MN, southwestern IA, southeastern NE, and northwestern KS, to another low related to both lee troughing and baroclinic processes over northeastern CO. By 12Z, the cold front should be decelerating across parts of Lake Superior, Upper MI, WI, and southern IA, then quasistationary to a low over central or north-central KS, then a cold front again southwestward across parts of the OK/TX Panhandles. By mid/late afternoon, the dryline should shift eastward to eastern KS, central OK, western north TX, and the Edwards Plateau, before retreating westward/northwestward overnight. ...Upper Mississippi Valley region... Multiple convective episodes are expected over the region through late evening, collectively contributing to the potential for large hail, damaging gusts and a few tornadoes. The initial episode is manifest as an arc of strong/isolated severe thunderstorms with mainly a hail threat over portions of northeastern SD, southeastern ND and west-central/southwestern MN. This activity is occurring in a zone of strong low-level warm advection and moisture transport, occurring as part of the mass response to the deepening low-level cyclone. See SPC mesoscale discussion 697 and severe-thunderstorm watch 192 for near-term details. For at least a few hours, this activity will move over a relatively stable boundary layer left from the nocturnal near-surface cooling, reinforced by precip. However, with favorable effective shear and buoyancy above the boundary layer, sporadic large hail will remain possible. A conditional threat will develop for some of this complex's gusts to penetrate to the surface later this morning, as a combination of warm advection, vertical mixing and weak diurnal heating destabilize the boundary layer. Behind the initial activity, a narrow, fairly fast-moving plume of superimposed low- and middle-level destabilization may develop this afternoon. Activity could be strongly tilted amidst effective-shear magnitudes of 60-75 kt, based on modified forecast soundings. Meanwhile, even with only meager low-level airmass recovery via warm advection and brief diurnal heating, cooling aloft should steepen deep-layer lapse rates enough for surface-based convection as far north as at least some of northern MN, with weak CINH and frontal lift forcing convection. Offering specifics on buoyancy always is a low-predictability endeavor in these limited-recovery, fast-flow, "bent-back arc" scenarios. Still, 250-500 J/kg MLCAPE appears possible in a narrow plume just ahead of the front over northern MN, increasing to 1500-3000 J/kg in a narrow corridor shifting eastward across southern MN and western WI. This may support a mix of multicells and supercells in an arc over MN, perhaps shifting/backbuilding into northwestern WI. A few tornadoes, occasional hail, and strong-damaging gusts all will be possible. Either backbuilding of the MN/WI arc, or initially separate development, will be possible late this afternoon into this evening along the cold front, over parts of WI into IA, also offering a multi-hazard severe threat. Boundary-layer moisture and lapse rates will be most favorable in this regime, but with only glancing influence of large-scale support aloft from the shortwave trough, before large-scale subsidence increases. Still, a line of convection may build along the boundary for a few hours, as frontal lift takes advantage of MLCINH minimized by both theta-e advection and residual diurnal warmth. 35-50 kt effective-shear magnitudes suggest blended supercell/multicell modes within the convective band, with well-mixed subcloud layers supporting survival of strong-severe gusts and large hail to the surface, before activity diminishes overnight. ..Edwards/Gleason.. 05/09/2022 Read more

WW 0192 Status Updates
STATUS FOR WATCH 0192 HAS NOT BEEN ISSUED YET Read more

WW 192 SEVERE TSTM MN 091255Z - 091800Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 192 NWS Storm Prediction Center Norman OK 755 AM CDT Mon May 9 2022 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Central Minnesota * Effective this Monday morning and afternoon from 755 AM until 100 PM CDT. * Primary threats include... Scattered large hail likely with isolated very large hail events to 2.5 inches in diameter possible Isolated damaging wind gusts to 70 mph possible SUMMARY...Thunderstorms, moving rapidly northeastward across the watch area this morning, will continue to offer occasional severe hail -- some potentially significant (2+ inches in diameter). The severe thunderstorm watch area is approximately along and 50 statute miles either side of a line from 40 miles northwest of Redwood Falls MN to 60 miles east of Brainerd MN. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU2). 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 2.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 22045. ...Edwards Read more