MD 0786 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR PORTIONS OF SOUTHERN AND CENTRAL MINNESOTA INTO NORTHWEST WISCONSIN
Mesoscale Discussion 0786 NWS Storm Prediction Center Norman OK 1208 PM CDT Thu May 15 2025 Areas affected...Portions of southern and central Minnesota into Northwest Wisconsin Concerning...Severe potential...Watch likely Valid 151708Z - 151945Z Probability of Watch Issuance...80 percent SUMMARY...Severe storms capable of all severe hazards (including very large hail and strong tornadoes) are expected this afternoon. Timing of storm development is uncertain, but one or more watches are likely early this afternoon. DISCUSSION...Potent mid-level ascent continues to lift into southern and central Minnesota late this morning. Earlier elevated convection north of the Twin Cities has weakened substantially and very minimal outflow is evident from that activity. A narrow warm sector is lifting ahead of a dryline feature. Despite cloud cover, temperatures continue to warm into the low/mid 70s F and cumulus are beginning to deepen along the dryline. Given the forcing for ascent, initiation of stronger storms within the next 2-3 hours appears reasonable and is supported by most recent CAM guidance. Strong effective shear across the surface boundaries should support at least initially discrete storms. Strong forcing aloft may promote some areas of quicker upscale growth into line segments. Mid-level lapse rates advecting into the region will support large/very large hail. Low-level southeasterly winds will promote large low-level hodographs (already evident on the KMPX VAD). Tornadoes, some potentially strong, will be possible. The tornado risk will likely be greater with southeastward extent on account of the broader warm sector. Scattered severe gusts are also expected given convective transport of strong low-level flow to the surface. The timing of development remains the biggest uncertainty along with the relatively narrow zone of tornado risk in Minnesota. One ore more watches are likely early this afternoon. ..Wendt/Mosier.. 05/15/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DLH...ARX...MPX...FGF... LAT...LON 44109429 45039564 45879603 46339554 46449406 45999278 45559214 44569190 43879237 43579286 44109429 MOST PROBABLE PEAK TORNADO INTENSITY...100-130 MPH MOST PROBABLE PEAK WIND GUST...55-70 MPH MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN Read more

WW 0252 Status Updates
STATUS FOR WATCH 0252 HAS NOT BEEN ISSUED YET Read more

WW 252 SEVERE TSTM AR KY MO TN 151855Z - 160000Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 252 NWS Storm Prediction Center Norman OK 155 PM CDT Thu May 15 2025 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of North-Central into Northeast Arkansas Far Western Kentucky Far Southeast Missouri Far Northwest Tennessee * Effective this Thursday afternoon and evening from 155 PM until 700 PM CDT. * Primary threats include... Scattered large hail likely with isolated very large hail events to 2.5 inches in diameter possible Scattered damaging wind gusts to 70 mph likely SUMMARY...Line of storms moving through north-central Arkansas continues to organize as it moves quickly eastward. The downstream airmass is warm and buoyant, suggesting the potential for this cluster to continue over the next few hours. Strong gusts and large to very large hail are possible with this cluster, as well any other storms that develop across the region. The severe thunderstorm watch area is approximately along and 75 statute miles east and west of a line from 15 miles east northeast of Poplar Bluff MO to 55 miles east southeast of Russellville AR. 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. && OTHER WATCH INFORMATION...CONTINUE...WW 251... 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 26040. ...Mosier Read more

WW 0251 Status Updates
STATUS FOR WATCH 0251 HAS NOT BEEN ISSUED YET Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1220 PM CDT Thu May 15 2025 Valid 161200Z - 171200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTHEAST MISSOURI...SOUTHERN ILLINOIS/INDIANA...AND CENTRAL AND WESTERN KENTUCKY... ...SUMMARY... A regional outbreak of severe thunderstorms is likely across parts of the middle Mississippi and Ohio Valleys Friday afternoon into Friday night. This may include a few intense supercells posing a risk for large hail and tornadoes. During the evening into the overnight hours, this will include an upscale growing and organizing bowing line of storms posing a risk for strong, damaging winds and a continuing risk for tornadoes. ...A regional outbreak of severe storms is expected on Friday across portions of the Mid-South to the Ohio Valley... ...Synopsis... An upper cyclone over the Upper Midwest and attendant shortwave trough will develop east/northeast across much of the Midwest and TN Valley. A swath of strong mid/upper southwesterly flow will accompany this system. Forecast guidance shows a 70-90 kt 500 mb jet spreading across the Mid-MS to OH Valley, while 850-700 mb increases to 40-60 kt by midday. This will result in supercell wind profiles, support widespread organized convection. Favorable deep-layer shear will extend downstream into the central Appalachians and Mid-Atlantic vicinity as well. At the surface, low pressure will shift east from northern MN into the Upper Great Lakes. A warm from southern MO into the OH Valley Friday morning is forecast to lift northward through the afternoon, allowing rich boundary layer moisture (mid/upper 60s F dewpoints) to overspread much of the Lower OH Valley, with a large warm sector in place across a broad region from east TX to the Great Lakes and eastward toward the Mid-Atlantic coast. Corridors of moderate to strong destabilization during the day and into the nighttime hours will support several areas of severe storms from east Texas into much of the Midwest and the Mid-Atlantic, some of which could be significant. ...Mid-MS Valley into the OH/TN Valley Vicinity... Forecast guidance depicts potential for remnant convection from Day 1/Thu ongoing across KY or TN Friday morning. Current expectation is that this activity will dissipate or weaken as it shifts east toward the central Appalachians. Strong warm advection should allow for rapid airmass recovery in the way of any morning thunderstorm activity. By midday, a very moist (mid 60s to low 70s F dewpoints) airmass will be in place beneath steep midlevel lapse rates, fostering MLCAPE around 2500-3500 J/kg from southeast MO northward to around the I-70 corridor and east toward the IN/KY. One or more clusters of convection is expected to develop by early afternoon within the strong warm advection regime and as large-scale ascent increases with the approach of the upper trough and an eastward-advancing cold front extending from eastern IA/western MO into central OK/TX around midday. Supercell wind profiles with enlarged low-level hodographs becoming elongated above 2-3 km within a volatile thermodynamic environment suggests convection will rapidly intensify. Any convection that remains discrete will pose a risk for very large hail (up to 3.5 inches), tornadoes (a few may be strong), and damaging gusts. With time, consolidation of thunderstorm clusters is expected and an organized bow is forecast to move across the OH/TN Valley region. Intense, damaging gusts greater than 70 kt will be possible once this occurs. Additional convection is expected to develop during the evening ahead of the advancing cold front from northern AR into western TN/KY. If this activity can remain discrete, supercells will pose an all-hazards severe risk. Eventually, this activity should become linear, but will still have an attendant wind/tornado risk, with a gradual weakening trend during the overnight hours expected across MS/AL/GA. ...Central Appalachians to Mid-Atlantic... Thunderstorms may be ongoing Friday morning across parts of PA and spread east/southeast through early afternoon as a lead upper shortwave impulse moves across the Northeast. Moistening and heating ahead of this activity will support moderate to strong destabilization, especially from the Chesapeake Bay vicinity southward across the VA/NC Piedmont. The initial round of thunderstorms may pose a risk for locally strong gusts and hail before moving offshore the NJ/DE/MD coast during the early afternoon. During the evening/overnight hours, a mature bowing MCS is expected to move over the WV/VA/NC mountains and spread east across the region, posing a risk for swaths of strong to damaging wind gusts. Forecast guidance varies in timing and exact evolution of this system across the region, but portions of the area may need higher probabilities in subsequent outlooks. ...WI/MI... Thunderstorms are expected to develop ahead of the surface low and cold front during the afternoon and evening. Cold temperatures aloft will support steep midlevel lapse rates and weak to moderate instability despite more modest boundary layer moisture. Favorable shear will support organized convection capable of isolated damaging gusts and hail. ...ArkLaTex vicinity... A more conditional risk of significant severe thunderstorms will exist across northeast TX into southern AR/northwest LA. A very moist and strongly unstable airmass will be in place, and forecast guidance suggests capping should erode along/ahead of the surface dryline. Low-level convergence along the surface boundary is not expected to be strong, and large-scale ascent will be nebulous, with neutral height tendencies expected. Nevertheless, at least a few storms are expected to develop during/just after peak heating. Supercell wind profiles, with long/straight hodographs are apparent in forecast soundings. Furthermore, thermodynamic profiles will be very favorable for large hail, while steepening low-level lapse rates will support strong outflow winds. Isolated significant hail (to 2.5 inches) is possible in addition to sporadic damaging gusts. ..Leitman.. 05/15/2025 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1137 AM CDT Thu May 15 2025 Valid 151700Z - 161200Z Cooler temperatures and lighter boundary layer winds will mitigate fire weather concerns across southeastern Arizona today, necessitating a slight pullback in Elevated highlights. Stronger mid-level winds and efficient mixing will continue to support an elevated fire weather threat across southern New Mexico into far west Texas. Downslope/leeward enhancement of surface winds should also occur across the High Plains of northeastern New Mexico. ..Williams.. 05/15/2025 .PREV DISCUSSION... /ISSUED 0104 AM CDT Thu May 15 2025/ ...Synopsis... An upper trough will quickly move eastward over the central US with accompanying strong mid-level flow. A deepening lee cyclone will intensify further as it move into the Upper Midwest tonight. As the low deepens, a Pacific cold front and tailing dryline will move quickly through the Rockies, into the Plains and Midwest States. Cooler temperatures, gusty westerly winds and some precipitation are possible along and behind the front through tonight. Elevated fire-weather conditions are possible over parts of the southern Plains and Southwest. ...Southwest... Persistent westerly flow will continue across the Southwest today and tonight as a weak pacific front moves over the Rockies. This will support another day of dry and windy conditions across parts of eastern AZ and southern NM. Despite somewhat cooler temperatures behind the front, downsloping and deep vertical mixing will support RH below 20% and winds of 15-20% amidst dry fuels. Widespread elevated to locally critical conditions are expected. Some fire-weather risk may also extend into West TX behind an eastward mixing dryline. However, winds here may be somewhat weaker despite very warm surface temperatures and lower humidity. Locally elevated conditions are possible within drying fuels. ...Central plains and Midwest... Gusty westerly winds are possible behind the advancing cold front from parts of the central Plains into western IA and MO this afternoon. While gusts may reach 20-25 mph, RH values are not expected to be critical with cooler temperatures. Additionally, recent wetting rainfall may temporarily limit available fuels. This suggests any fire-weather concerns will be localized and short lived. ...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 1128 AM CDT Thu May 15 2025 Valid 151630Z - 161200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS EAST-CENTRAL MINNESOTA...MUCH OF WISCONSIN...SOUTHERN AND WESTERN LOWER MICHIGAN...NORTHEAST ILLINOIS...NORTHERN INDIANA AND NORTHWEST OHIO... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF VIRGINIA AND NORTHEAST NORTH CAROLINA... ...SUMMARY... Severe thunderstorms are expected across parts of the upper Mississippi River Valley and Great Lakes this afternoon and evening. Tornadoes, some of which could be strong, and very large hail and damaging winds will be possible. Severe thunderstorms are also expected through the lower Ohio River Valley, Ozarks and in parts of the Mid-Atlantic. ...Mid to Upper Mississippi Valley/Great Lakes/Ohio Valley... Recent satellite imagery shows an upper low over SD, with a negatively tilted shortwave trough moving into the Mid MO Valley. Surface analysis places an occluded surface low associated with this system over southeast ND, with an occluded front extending southeastward to a triple point over far southeast SD. A cold front extends south-southeastward from this front across far western IA and into far northeast MO before arcing more southwestward across far western MO and more southwestward across western OK. A warm front extends easterward from this triple point across southern MN and then more southeastward across southwest WI and northern IL. These boundaries, including the occluded front, will all act in tandem with increasing large-scale forcing for ascent to force thunderstorm development this afternoon and evening. The ongoing storms from eastern SD into central MN are confirmation of the buoyancy sampled in the 12Z MPX sounding. Expectation is for instability to build across the region as heating and low-level moisture advection occur amid steep mid-level lapse rates. Airmass destabilization and thunderstorm development is anticipated first from the eastern Dakotas into MN, the occluded front as it shifts northward as both the primary surface low and triple point low shift northwestward. Additional development is then anticipated farther southeast along the warm front across WI. Storms that develop in the vicinity of the occluded front will likely have elevated structures, with large hail as the primary risk. Some isolated very large hail (i.e. greater than 2" in diameter) is possible. Farther southeast, the corridor along the warm front appears very favorable for supercells capable of all severe hazards, including very large hail, strong wind gusts, and tornadoes. A locally higher tornado potential may exist from central into southeastern WI from 18Z-22Z. Deeper mixing is anticipated farther south into northern IL, but the overall environment will still support robust, organized updrafts. There may be some trend initially for these storms to quickly become outflow dominant, but strengthening mid-level flow across the region after 21Z should aid in maintaining a more organized mode. Upscale growth into a organized MCS appears probable after 00Z, with the potential for significant-severe gusts as this line moves eastward in southern Lower MI. The threat for damaging gusts and isolated hail will persist throughout the night across Lower MI and the middle/upper OH Valley. ...Ozarks into the TN Valley... Additional thunderstorm development is anticipated this afternoon across AR as a cold front pushes eastward across the region. Moderate to strong flow aloft should allow for storms to move off this boundary quickly into a strongly buoyant airmass downstream. Warm air aloft could limit overall storm longevity during the afternoon/early evening, but the warm/dry mid-levels are conducive for producing strong outflows capable of damaging gusts. Whether or not organization will occur along these outflows is uncertain, but a conditional risk for continued damaging gusts exists into TN. Additional thunderstorms are possible during the evening and overnight in the wake of the front. Persistent steep mid-level lapse rates and strong shear will support large hail with some of these storms. ...Central Appalachians/Mid-Atlantic... Large-scale height rises are expected across the region, but diurnal heating and orographic effects will aid in thunderstorm development across the higher terrain this afternoon. Northwesterly flow aloft will favor a southeastward storm motion within an environment of moderate/locally strong instability. 35-45 kts of northwesterly deep shear is anticipated, supporting supercell structures and clusters, posing a risk for large hail and damaging winds. The overall hodograph structure and resulting storm motion appears favorable for some very large hail over 2" in diameter as well. ..Mosier.. 05/15/2025 Read more

No watches are valid as of Thu May 15 14:02:02 UTC 2025.

No Mesoscale Discussions are in effect as of Thu May 15 14:02:02 UTC 2025.

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Thu May 15 2025 Valid 151300Z - 161200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS EAST-CENTRAL MINNESOTA...MUCH OF WISCONSIN...SOUTHERN AND WESTERN LOWER MICHIGAN...NORTHEAST ILLINOIS...NORTHERN INDIANA AND NORTHWEST OHIO... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF VIRGINIA AND NORTHEAST NORTH CAROLINA... ...SUMMARY... Severe thunderstorms are expected across parts of the upper Mississippi River Valley and Great Lakes this afternoon and evening. Tornadoes, some of which could be strong, and very large hail and damaging winds will be possible. Severe thunderstorms are also expected through the lower Ohio River Valley, Ozarks and in parts of the Mid-Atlantic. ...Mid to Upper Mississippi Valley/Great Lakes/Ohio Valley... A deepening surface low will gradually consolidate as it moves north across the eastern Dakotas today, and a warm front will lift north through the OH Valley and into WI/Lower MI late this afternoon. As strong large-scale ascent develops in association with a northeast-moving/negatively-tilted upper trough and left exit region of a 300-mb jet streak, rapid thunderstorm development, or re-intensification of ongoing storms, is expected from near the surface low east/southeast along an arcing occluded/cold front over central MN/western WI/northeast IL. A broken line of semi-discrete cells is anticipated within a strongly unstable and amply-sheared environment supporting supercell storm structures. Large hail, possibly very large and in excess of 2.5 inches in diameter, will be possible in addition to damaging wind gusts. Low-level shear will support the potential for tornadoes with mature supercells, and the risk for strong tornadoes will exist, especially towards evening as low-level shear increases. Storms should tend to merge into clusters or line segments with time, especially across southern lower MI/northern IN/OH, where significant severe wind potential will exist with an eastward moving complex of storms. The 30% wind/sig severe wind area was extended east into southeast lower MI based on latest hi-res guidance. ...Ozarks... Thunderstorms have developed along the Red River in southeast OK/western AR this morning, along the southern periphery of stronger mid-level flow and with moderate elevated buoyancy. Although larger-scale forcing remains nebulous, these storms may continue to intensify and become surface based with time with the onset of diurnal destabilization. Strong southwesterly flow will contribute to ample deep-layer shear for supercells or a small cluster. Severe hail and perhaps wind will be the primary severe hazards as storms move across AR towards the mid-Mississippi Valley, and the Slight (Level 2) Risk has been extended southwest across northern AR for this potential. ...Central Appalachians/Mid-Atlantic... Scattered thunderstorms are expected to develop in response to diurnal heating and across the higher terrain this afternoon, and move southeast within an environment of moderate/locally strong surface-based instability and 35-40 kts of northwesterly deep shear. In this parameter space, supercell structures and clusters will be possible and pose a risk for large hail and damaging winds. Trends in the 00z HREF and early morning hi-res guidance were the basis for extending the Slight (Level 2) Risk southeast across portions of northeast NC. ..Bunting/Dean.. 05/15/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Thu May 15 2025 Valid 151300Z - 161200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS EAST-CENTRAL MINNESOTA...MUCH OF WISCONSIN...SOUTHERN AND WESTERN LOWER MICHIGAN...NORTHEAST ILLINOIS...NORTHERN INDIANA AND NORTHWEST OHIO... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF VIRGINIA AND NORTHEAST NORTH CAROLINA... ...SUMMARY... Severe thunderstorms are expected across parts of the upper Mississippi River Valley and Great Lakes this afternoon and evening. Tornadoes, some of which could be strong, and very large hail and damaging winds will be possible. Severe thunderstorms are also expected through the lower Ohio River Valley, Ozarks and in parts of the Mid-Atlantic. ...Mid to Upper Mississippi Valley/Great Lakes/Ohio Valley... A deepening surface low will gradually consolidate as it moves north across the eastern Dakotas today, and a warm front will lift north through the OH Valley and into WI/Lower MI late this afternoon. As strong large-scale ascent develops in association with a northeast-moving/negatively-tilted upper trough and left exit region of a 300-mb jet streak, rapid thunderstorm development, or re-intensification of ongoing storms, is expected from near the surface low east/southeast along an arcing occluded/cold front over central MN/western WI/northeast IL. A broken line of semi-discrete cells is anticipated within a strongly unstable and amply-sheared environment supporting supercell storm structures. Large hail, possibly very large and in excess of 2.5 inches in diameter, will be possible in addition to damaging wind gusts. Low-level shear will support the potential for tornadoes with mature supercells, and the risk for strong tornadoes will exist, especially towards evening as low-level shear increases. Storms should tend to merge into clusters or line segments with time, especially across southern lower MI/northern IN/OH, where significant severe wind potential will exist with an eastward moving complex of storms. The 30% wind/sig severe wind area was extended east into southeast lower MI based on latest hi-res guidance. ...Ozarks... Thunderstorms have developed along the Red River in southeast OK/western AR this morning, along the southern periphery of stronger mid-level flow and with moderate elevated buoyancy. Although larger-scale forcing remains nebulous, these storms may continue to intensify and become surface based with time with the onset of diurnal destabilization. Strong southwesterly flow will contribute to ample deep-layer shear for supercells or a small cluster. Severe hail and perhaps wind will be the primary severe hazards as storms move across AR towards the mid-Mississippi Valley, and the Slight (Level 2) Risk has been extended southwest across northern AR for this potential. ...Central Appalachians/Mid-Atlantic... Scattered thunderstorms are expected to develop in response to diurnal heating and across the higher terrain this afternoon, and move southeast within an environment of moderate/locally strong surface-based instability and 35-40 kts of northwesterly deep shear. In this parameter space, supercell structures and clusters will be possible and pose a risk for large hail and damaging winds. Trends in the 00z HREF and early morning hi-res guidance were the basis for extending the Slight (Level 2) Risk southeast across portions of northeast NC. ..Bunting/Dean.. 05/15/2025 Read more

MD 0785 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR SOUTHEAST SD...SOUTHERN MN...EXTREME NORTHEAST NE/NORTHWEST IA
Mesoscale Discussion 0785 NWS Storm Prediction Center Norman OK 0723 AM CDT Thu May 15 2025 Areas affected...Southeast SD...southern MN...extreme northeast NE/northwest IA Concerning...Severe potential...Watch unlikely Valid 151223Z - 151400Z Probability of Watch Issuance...20 percent SUMMARY...A threat for strong to isolated severe storms may continue through the morning. DISCUSSION...A long-lived storm cluster is ongoing this morning across south-central MN. This system has persisted longer than most guidance would suggest, and is likely being aided by persistent moisture transport associated with a strong low-level jet. While this system remains relatively disorganized with outflow tending to outpace the deeper convection, localized strong wind gusts and hail will be possible, especially where new updrafts develop and briefly intensify behind the outflow. To the southwest, renewed storm development is underway across southeast SD and far northeast NE, immediately in advance of a compact but vigorous midlevel shortwave trough moving across north-central NE/south-central SD. Rather strong low-level southeasterly flow will maintain moisture transport into the region through the morning ahead of a cold front, and development of somewhat more organized convection will be possible with time. In the short term, convection will tend to be somewhat elevated, but could become rooted closer to the surface later this morning, especially with southeast extent. Some hail and strong-gust potential could evolve if convection is able to deepen and intensify within this regime. With the threat expected to remain rather isolated over the next 1-2 hours, short-term watch issuance is considered unlikely. Trends will continue to be monitored for intensification with time this morning. ..Dean/Bunting.. 05/15/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ARX...MPX...DMX...FSD...OAX...ABR... LAT...LON 43759861 44979732 45289595 45409490 45409384 45129316 44599296 44179290 43649334 43539415 43479504 43269575 42909627 42609653 42449683 42619714 42779752 42999832 43759861 MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH MOST PROBABLE PEAK WIND GUST...55-70 MPH MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN Read more

MD 0784 CONCERNING SEVERE THUNDERSTORM WATCH 250... FOR PARTS OF EASTERN SD INTO SOUTHWEST MN AND FAR NORTHWEST IA
Mesoscale Discussion 0784 NWS Storm Prediction Center Norman OK 0404 AM CDT Thu May 15 2025 Areas affected...Parts of eastern SD into southwest MN and far northwest IA Concerning...Severe Thunderstorm Watch 250... Valid 150904Z - 151030Z The severe weather threat for Severe Thunderstorm Watch 250 continues. SUMMARY...An isolated severe threat may spread northeast out of WW 250 with time this morning. DISCUSSION...A long-lived storm cluster has evolved into a bowing MCS (with embedded cellular elements) from far eastern SD into southwest MN, and strong to locally severe gusts have been reported over the last hour to the northeast of Sioux Falls, SD. Small mesovortices have occasionally been noted along the leading edge of the line, and a threat for localized severe gusts could be maximized with these features, especially where the outflow has not surged ahead of the deeper convection. The northern portion of the line will tend to move into a cooler and less unstable environment with time, though more substantial moisture return above the surface could maintain robust elevated convection through the early morning. The southern portion of the line will be in closer proximity to increasing MLCAPE and weaker MLCINH, though lingering near-surface stability may hamper reintensification potential. An isolated severe threat may spread northeast out of WW 250 with time, though the need for downstream watch issuance is uncertain. ..Dean/Bunting.. 05/15/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MPX...DMX...FSD...ABR... LAT...LON 44179616 45139736 45729686 45619575 45459489 45319442 45059420 44679403 44419403 43999424 43239470 42899540 42889580 43099623 44179616 MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH MOST PROBABLE PEAK WIND GUST...55-70 MPH MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0358 AM CDT Thu May 15 2025 Valid 181200Z - 231200Z ...DISCUSSION... Medium-range guidance indicates that the persistent, prominent mid/upper ridging across the mid-latitude and subtropical eastern Pacific will become suppressed late this coming weekend into early next week, before breaking down through the remainder of this period. As it does, amplified downstream troughing is forecast to emerge from the Intermountain West. Sunday, this may commence gradually, with one significant lead short wave perturbation pivoting north-northeast of the southern Rockies, accompanied by cyclogenesis across eastern Colorado, as an upstream perturbation continues to dig toward the Four Corners region. It appears that this trailing perturbation will then pivot across the southern Rockies through the central/southern Great Plains by late Monday, perhaps accompanied by renewed cyclogenesis across the Texas Panhandle into central Great Plains. Both days, the dryline and warm front may provide focus for organized severe convective development, including supercells, in the presence of strong deep-layer shear and thermodynamic profiles characterized by steep lapse rates and sizable CAPE. It appears that a substantive risk for strong to severe thunderstorms will persist into at least Tuesday, within a broadening warm sector as the cyclone and associated mid-level troughing shift a bit more rapidly eastward across the middle Mississippi Valley. Convective potential becomes more unclear Wednesday into Thursday as the cyclone likely weakens and synoptic developments become more uncertain across the East. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0358 AM CDT Thu May 15 2025 Valid 181200Z - 231200Z ...DISCUSSION... Medium-range guidance indicates that the persistent, prominent mid/upper ridging across the mid-latitude and subtropical eastern Pacific will become suppressed late this coming weekend into early next week, before breaking down through the remainder of this period. As it does, amplified downstream troughing is forecast to emerge from the Intermountain West. Sunday, this may commence gradually, with one significant lead short wave perturbation pivoting north-northeast of the southern Rockies, accompanied by cyclogenesis across eastern Colorado, as an upstream perturbation continues to dig toward the Four Corners region. It appears that this trailing perturbation will then pivot across the southern Rockies through the central/southern Great Plains by late Monday, perhaps accompanied by renewed cyclogenesis across the Texas Panhandle into central Great Plains. Both days, the dryline and warm front may provide focus for organized severe convective development, including supercells, in the presence of strong deep-layer shear and thermodynamic profiles characterized by steep lapse rates and sizable CAPE. It appears that a substantive risk for strong to severe thunderstorms will persist into at least Tuesday, within a broadening warm sector as the cyclone and associated mid-level troughing shift a bit more rapidly eastward across the middle Mississippi Valley. Convective potential becomes more unclear Wednesday into Thursday as the cyclone likely weakens and synoptic developments become more uncertain across the East. Read more

WW 0249 Status Updates
STATUS REPORT ON WW 249 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 10 NNE OFK TO 25 SSW YKN TO 20 WSW FSD TO 30 W BKX TO 10 NNE HON. ..DEAN..05/15/25 ATTN...WFO...OAX...LBF...GID...FSD... STATUS REPORT FOR WS 249 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NEC051-150840- NE . NEBRASKA COUNTIES INCLUDED ARE DIXON SDC027-150840- SD . SOUTH DAKOTA COUNTIES INCLUDED ARE CLAY THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 0250 Status Updates
STATUS REPORT ON WW 250 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..DEAN..05/15/25 ATTN...WFO...FSD... STATUS REPORT FOR WS 250 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS IAC021-035-041-059-093-119-141-143-149-167-193-150840- IA . IOWA COUNTIES INCLUDED ARE BUENA VISTA CHEROKEE CLAY DICKINSON IDA LYON O'BRIEN OSCEOLA PLYMOUTH SIOUX WOODBURY MNC033-063-081-083-101-105-117-133-150840- MN . MINNESOTA COUNTIES INCLUDED ARE COTTONWOOD JACKSON LINCOLN LYON MURRAY NOBLES PIPESTONE ROCK NEC043-150840- NE . NEBRASKA COUNTIES INCLUDED ARE Read more

WW 250 SEVERE TSTM IA MN NE SD 150635Z - 151400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 250 NWS Storm Prediction Center Norman OK 135 AM CDT Thu May 15 2025 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Northwest Iowa Southwest Minnesota Extreme northeast Nebraska Southeast South Dakota * Effective this Thursday morning from 135 AM until 900 AM CDT. * Primary threats include... Scattered damaging wind gusts to 70 mph likely Isolated very large hail events to 2 inches in diameter possible A tornado or two possible SUMMARY...A line of severe thunderstorms will continue moving northeast across the watch area this morning with a risk for damaging wind gusts and isolated large hail. The severe thunderstorm watch area is approximately along and 35 statute miles east and west of a line from 25 miles east northeast of Brookings SD to 30 miles east southeast of Sioux City IA. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU0). 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 249... 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 24035. ...Bunting Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0229 AM CDT Thu May 15 2025 Valid 171200Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SATURDAY ACROSS PARTS OF EASTERN NORTH CAROLINA...EASTERN VIRGINIA...CENTRAL AND EASTERN MARYLAND...DELAWARE...SOUTHEASTERN PENNSYLVANIA...CENTRAL AND SOUTHERN NEW JERSEY AND LATE SATURDAY INTO SATURDAY NIGHT ACROSS PARTS OF WEST CENTRAL THROUGH NORTH CENTRAL TEXAS...EASTERN OKLAHOMA AND SOUTHWESTERN INTO CENTRAL ARKANSAS... ...SUMMARY... Severe thunderstorms are possible Saturday across parts of the Mid Atlantic, and late Saturday into Saturday night across parts of the southeastern Great Plains. ...Discussion... Downstream of a persistent, prominent mid-level ridge across the southern mid-latitude and subtropical eastern Pacific, models indicate that large-scale troughing will continue to dig inland of the Pacific coast through this period. It appears that this will include one notable embedded smaller-scale perturbation digging across the Sierra Nevada, toward the Four Corners, and a trailing perturbation digging across the Pacific Northwest coast. Farther downstream, it appears that one or two more modest short wave impulses, within a belt of westerlies emanating from the subtropical eastern Pacific, may accelerate across the northern Mexican Plateau through the southern Great Plains and lower Mississippi Valley, around the northwestern periphery of broad mid/upper ridging centered over the Gulf Basin. To the north of this ridge, large-scale ridging within the mid-latitude westerlies is forecast to overspread much of the interior U.S., with a remnant downstream cyclone and associated troughing progressing across parts of the Northeast and Mid Atlantic. In lower levels, models generally indicate that a significant cold front will advance southeast of the lower Great Lakes and Ohio Valley, while stalling across parts of the Mid South into central Great Plains. However, this is likely to be preceded by a weaker front, largely driven or reinforced by outflow from Friday/Friday night convection. ...Mid Atlantic... Strong convectively augmented westerly lower/mid-tropospheric flow (in excess of 50 kt in the 850-700 mb layer) is likely to spread east of the Allegheny and Blue Ridge Mountains, coincident with the convective outflow boundary by early Saturday. The extent and intensity of continuing convective development along the gust front at the outset of the period remains unclear. However, if the severe storm cluster from Friday night does not maintain strength with a continuing risk for severe wind gusts into and across the Mid Atlantic early Saturday, it is possible that destabilization ahead of the surface boundary could become sufficient for considerable re-intensification of thunderstorm activity along it, before it advances offshore. ...Southeastern Great Plains... Beneath steep lower/mid-tropospheric lapse rates, models indicate that seasonably moist air will maintain a reservoir of large CAPE along and south of the initial pre-frontal wind shift/convective outflow, roughly across the Ark-La-Texas, and east of a sharpening dryline, across western North Texas toward the Del Rio TX area by late afternoon. Aided by forcing for ascent and strengthening westerly mid/upper flow associated with the subtropical perturbations, isolated to scattered supercells may initiate and propagate off the retreating dryline by late afternoon. Other strong to severe thunderstorm development is possible, aided by forcing for ascent associated with warm advection, where mid-level inhibition will be weaker along and north of the initial pre-frontal wind shift, and perhaps near the surface front across northern Oklahoma into north central Arkansas. ..Kerr.. 05/15/2025 Read more

MD 0783 CONCERNING SEVERE THUNDERSTORM WATCH 249... FOR NORTHEAST NE...SOUTHEAST SD...NORTHWEST IA...SOUTHWEST MN
Mesoscale Discussion 0783 NWS Storm Prediction Center Norman OK 0108 AM CDT Thu May 15 2025 Areas affected...Northeast NE...southeast SD...northwest IA...southwest MN Concerning...Severe Thunderstorm Watch 249... Valid 150608Z - 150745Z The severe weather threat for Severe Thunderstorm Watch 249 continues. SUMMARY...Some severe threat could spread northeast overnight. DISCUSSION...A long-lived storm cluster is moving northeastward across northeast NE and southeast SD early this morning, downstream of a midlevel shortwave trough and possible MCV over north-central NE. A rather strong low-level jet (evident on the KOAX and KFSD VWPs) and favorable upper-level difluence will help to maintain convection through the overnight hours. Moderate buoyancy will spread into a larger portion of eastern SD and southwest MN overnight, while modestly favorable deep-layer shear will continue to support organized convection. The strongest storms within this cluster will continue to be capable of producing isolated large hail and strong to locally severe gusts. Some increase in severe-wind potential is possible if more organized upscale growth occurs overnight, though this potential remains uncertain. Also, while the bulk of convection may remain somewhat elevated, there remains some conditional potential for near-surface-based supercells within the southern part of the cluster, and a tornado cannot be ruled out. With WW 249 scheduled to expire at 3 AM CDT, new watch issuance is possible overnight, depending on short-term observational trends. ..Dean/Bunting.. 05/15/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MPX...FSD...OAX...ABR...GID...LBF... LAT...LON 41569836 42179845 43439770 44719794 44939635 44539570 44009534 43049538 42369564 41699654 41569748 41569788 41569836 MOST PROBABLE PEAK TORNADO INTENSITY...85-115 MPH MOST PROBABLE PEAK WIND GUST...65-80 MPH MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN Read more