
Mesoscale Discussion 0496
NWS Storm Prediction Center Norman OK
1137 AM CDT Wed Apr 22 2026
Areas affected...far southern Lower MI...northern IN...and northwest
OH
Concerning...Severe potential...Watch unlikely
Valid 221637Z - 221900Z
Probability of Watch Issuance...20 percent
SUMMARY...Thunderstorm coverage will increase over the next couple
of hours, and storms will persist into early evening. The strongest
storms may produce marginally severe hail near 1 inch diameter and
locally strong gusts. A watch is not currently expected.
DISCUSSION...An isolated thunderstorm over southeast Lake Michigan
has persisted over the past hour as it slowly approaches the MI/IN
coast. During this time, MRMS MESH has estimated hail to near 1
inch. Most recently, 5 and 7 km CAPPI has decreased and echo tops
have lowered. It is unclear if this storm will continue inland. If
so, it could become reinvigorated as it moves into modestly better
low-level moisture near a surface boundary extending west to east
across far southern Lower MI/northern IN and northwest OH.
Additional storm development is expected near/south of this surface
boundary over the next couple of hours as strong heating continues.
Steepened low-level lapse rates may support locally strong gusts
with this activity. Additionally, cool temperature aloft are
supporting modest midlevel lapse rates, fostering MUCAPE around 1000
J/kg. Strengthening northwesterly flow aloft may aid in a few better
organized cells capable of producing marginally severe hail through
early evening. Given the overall modest environment, a severe
thunderstorm watch is not currently expected.
..Leitman/Mosier.. 04/22/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CLE...ILN...DTX...IWX...GRR...IND...LOT...
LAT...LON 41868712 42048692 42258625 42318524 42308506 42238434
41998372 41738331 41508318 40638316 40268362 40158458
40348532 40858626 41368683 41758706 41868712
MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN
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Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1222 PM CDT Wed Apr 22 2026 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTHERN KANSAS INTO SOUTHERN MINNESOTA... ...SUMMARY... Severe thunderstorms will be possible from southern Kansas into southern Minnesota on Thursday. Large hail to very large hail, damaging winds, and a few tornadoes are possible. ...Synopsis... A short-wave trough initially over the northern High Plains Thursday morning is forecast to shift east across the northern Plains into the upper MS Valley in tandem with a belt of 50-60 kt south-southwest winds in the mid levels. A secondary, lower-latitude disturbance will advance into western KS and the OK/TX panhandles late Thursday afternoon into evening, along with a more zonal mid/upper-level jet streak. At the surface, the primary cyclone attendant to the northern Plains system is expected to undergo occlusion over southern into central Manitoba, while a trailing cold front progresses east through the northern Plains into the upper MS Valley. A pre-frontal trough or pseudo-dryline will precede the cold front, extending from western MN through western IA and eastern NE into central KS by early to mid afternoon. A secondary surface low is forecast to deepen across portions of southwest KS or northwest OK Thursday afternoon in response to the approach of the lower-latitude disturbance mentioned above. A more classic dryline will extend south from that low through western OK into western north TX during the peak of the diurnal heating cycle. ...Upper MS Valley and upper Midwest through the mid/lower MO Valley into central/eastern KS... A broad, nocturnal, low-level wind maximum will develop across the Great Plains tonight (Wed. night), enhancing the poleward flux of an increasingly moist boundary layer beneath a residual EML plume residing across the same region. The moisture increase beneath a capping inversion at the base of the EML may result in considerable cloud cover Thursday afternoon across portions of the warm sector air mass. Where cloud breaks occur, model soundings indicate the potential for MLCAPE to approach 1000-1500 J/kg across portions of southern MN to as high as 2000-3000+ J/kg in central and eastern KS. By early to mid afternoon, convergence along the pre-frontal trough/dryline coupled with increasing height falls/forcing for ascent are expected to support widely scattered thunderstorms from portions of central and southern MN through eastern NE and western IA, into at least northeast KS. While the strongest mid/upper-level wind fields are expected to remain to the immediate west of the initiating boundary, a corridor of 40-45 kt effective bulk shear will overlie the western fringe of the warm sector, supporting organized multicells and supercells as the initial storm mode with an attendant threat for large to very large hail and a few tornadoes. Subsequent upscale growth into a broken band of storms is expected Thursday evening into Thursday night across portions of eastern MN into western WI, western and central IA, southeast NE, northeast KS, and northwest MO. Damaging wind potential will increase with that mode change, with a continued risk for a few tornadoes. The most favorable overlap of moderate to strong instability and vertical wind shear is expected to develop across central into eastern KS Thursday afternoon into evening. Here, a few intense supercells capable of all severe-weather hazards appear possible, and a categorical upgrade to a level 3/Enhanced Risk may be required in subsequent Day 1 outlooks. ...OK into north TX... Moderate to strong instability (MLCAPE of 2500-3500 J/kg) is expected to develop east of the dryline by late afternoon into early evening on Thursday. However, strong capping at the base of the EML casts considerable uncertainty on whether storms can develop. While the strongest forcing for ascent associated with the secondary short-wave trough is expected to remain across KS, subtle mid-level height falls are forecast across northern OK. Otherwise, strong heating to the west of the dryline and resultant deepening circulations along it will be the primary mechanism responsible for any storm development. On the condition that isolated storms develop and become sustained, the kinematic environment will support supercells capable of very large hail and tornadoes. This is especially the case during the evening hours as low-level shear strengthens in response to the amplification of the low-level jet. ..Mead.. 04/22/2026Read more

Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1128 AM CDT Wed Apr 22 2026 Valid 221630Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FOR PARTS OF THE HIGH PLAINS/NORTHERN PLAINS...AND ACROSS FAR SOUTHERN LOWER MICHIGAN...NORTHEAST INDIANA INTO NORTHERN OHIO... ...SUMMARY... Isolated strong-severe thunderstorms with strong gusts and hail will be possible across parts of the High Plains this afternoon and evening, as well as from northeast Indiana into northern Ohio. ...Synopsis... Recent surface analysis shows an airmass modifying under low-level moisture advection across the southern and central Plains, with mid 50s dewpoints reaching through central KS and into eastern NE/western IA. This moderate low-level moisture also extends eastward from IA into northern IL and IN, just south of a stationary boundary that demarcates a drier, more stable airmass across much of the Great Lakes from the modifying airmass farther south/southwest. This analysis also reveals a pair of surface lows, one over north-central MT and the other over far northeast WY/far southeast MT, linked by modest surface troughing. A wavy surface trough also extends southward to another low over southeast CO. Thunderstorm development is anticipated today/tonight near these lows and their related surface boundaries. In particular, strong to isolated severe thunderstorms appear possible near the northeast WY/far southeast MT low as it moves eastward across SD, as well as in the vicinity of the stationary boundary across northern IN and OH. ...IN/OH... Weak surface low over southern Lower MI has already contributed to thunderstorm development. The airmass downstream of this low, and south of the stationary boundary that extends east-to-west near the MI and IN/OH border vicinity, will likely destabilize throughout the day amid continued low-level moisture advection and strong diurnal heating. This destabilization coupled with low-level convergence near the low and boundary will support increasing thunderstorm coverage. Deep-layer wind profiles will be modest, but cool mid-level temperatures and weak-moderate buoyancy could support isolated severe hail and gusty outflow winds with the strongest storms. ...High Plains... Primary surface low over central MT is forecast to deepen today as a closed upper low currently over the Great Basin ejects northeastward while evolving towards a more open wave. At the same time, a secondary surface low (currently over far northeast WY/far southeast MT) is forecast to move eastward across SD, interacting with the modifying airmass across the northern/central Plains. Expectation is for this airmass to be deeply mixed, with perhaps some minimal buoyancy atop the well-mixed boundary layer. Development of a few high-based thunderstorms is possible this afternoon/evening from NE into SD, as well as northeast MT, along the trough where deep mixing and inverted-v profiles will favor strong outflow gusts. Farther south, an even more conditional risk is anticipated along a sharpening dryline from southwest NE and western KS into west TX. Given the limited large-scale forcing and only weak low-level convergence, warm mid-level temperatures and related capping associated with a notable elevated mixed layer will likely suppress thunderstorm development. Here, deep-layer vertical shear will be sufficient for supercells, and a conditional risk for large hail and strong gusts exists with any updrafts that are able to persist and mature. ...Western/Central NE into the Dakotas... Additional thunderstorms are possible tonight from western/central NE into the Dakotas as an eastward-progressing cold front interacts with low-level moisture continuing to advect northward across the Plains and a strengthening low-level jet. These storms will likely be elevated behind the front, with some isolated hail possible early in the convective cycle. Additionally, mid-level dry air will likely remain across the region, supporting the potential for strong outflow gusts despite the storms elevated character. ..Mosier/Lyons.. 04/22/2026Read more

Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1049 AM CDT Wed Apr 22 2026 Valid 221700Z - 231200Z ...CRITICAL FIRE WEATHER AREA FOR EAST-CENTRAL NEW MEXICO INTO THE NORTHERN HIGH PLAINS... ...CRITICAL FIRE WEATHER AREA FOR NORTH-CENTRAL NEBRASKA INTO CENTRAL SOUTH DAKOTA... ...Morning Update... No changes were made to the previous forecast. Despite good overnight humidity recoveries across portions of the High Plains, widespread surface RH is decreasing rapidly as temperatures rise and deeper mixing into a dry airmass aloft ensues. Along the lee of the Rockies into central MT, surface observations depict poor overnight humidity recoveries have resulted in widespread 15-25 percent RH this morning. High cloud cover east of the Divide will slowly clear out late this morning before more spotty clouds build in this evening. However, as the surface low strengthens across eastern MT, strong surface winds and a deepening dry airmass aloft will continue to support critically low RH atop very dry fuels. A 700 mb 50-70 kt jet will develop east of the Laramie range through southwestern SD this evening as the surface low strengthens, dragging a cold front across the central Plains tonight. Strong west-northwesterly winds of 20-30 mph will continue behind the front east of the Laramie Range into the NE Panhandle with RH only increasing to 30-50 percent. These conditions will likely persist through nearly the entire overnight period, further exacerbating the fire environment. See the previous discussion for more information. ..Elizalde-Garcia.. 04/22/2026 .PREV DISCUSSION... /ISSUED 1256 AM CDT Wed Apr 22 2026/ ...Synopsis... A robust and progressive upper-level trough will move into the Northern Rockies through today with an associated strong mid-level jet stretching from the southern Great Basin to the Northern Plains. An incipient lee surface low will deepen across eastern MT, while strengthening lee troughing extends southward into the central and southern High Plains. The broad southwest flow aloft and surface troughing will support a expansive fire weather threat across much of High Plains. Ascent ahead of the upper trough will aid in high based thunderstorm development along a dry line across portions of the Central Plains. ...Southwest and portions of the High Plains... A broad fire weather concern is still expected across portions of the Southwest and High Plains corridor. The approaching mid-level trough and related jet along with strengthening lee surface troughing amid dry and breezy conditions will promote Critical fire weather conditions across much of the High Plains, with a more expansive Elevated fire weather concern into the northern High Plains and Upper Midwest. The strongest southwest winds of 25-30 mph will be focused across WY and southeastern MT, more coincident with the mid-level jet max. Southwest winds of 20-25 mph along the central and southern High Plains are expected by this afternoon while downslope trajectories yield single digit RH values atop very dry and still dormant fuels. Critical fire weather highlights were maintained for this region with a locally Extremely Critical fire weather threat, including 30+ mph winds with higher gusts, possible in favored terrain gaps of the CO Front Range. ...North-central Nebraska into central South Dakota... Increasing southerly winds approaching 30 mph by mid afternoon attributed to a deepening surface trough are expected across portions of NE Sandhills northward into central SD. Delayed boundary layer moisture return should result in critically low RH of 10-15% by peak afternoon heating. These conditions combined with very receptive fuels will promote several hours of critical fire weather conditions through the early afternoon. Initial influx of thunderstorms could produce strong to locally severe wind gusts late this afternoon, before improving conditions including potential for wetting rains move into the area this evening. ...Far southwestern South Dakota, western Nebraska, far eastern Colorado and western KS... Isolated high based thunderstorms are possible this afternoon across portions of the central Plains stretching southward from southwestern SD almost to the OK Panhandle. The incoming upper trough and associated ascent and convergence along the dry line should allow for isolated thunderstorms to develop by early afternoon. Deeper boundary layer moisture will reside across the Southern Plains with precipitable water values of 0.50"-0.70" just east of the dry line supporting only minimal precipitation as thunderstorms propagate eastward through the evening. Isolated Dry Thunderstorm highlights were extended farther south into far southeastern CO and western KS based on latest forecast guidance. ...Piedmont and portions of Mid Atlantic... West to southwest winds ahead of a cold front will affect portions of the Mid Atlantic and Piedmont today where fuels remain critically dry. Wind speeds of 10-15 mph along with RH falling into the 20-25% during the afternoon will yield elevated fire weather concerns for southern VA, much of NC and northern SC. An embedded mid-level wave within broader northwest flow and modest 850 mb northwest winds will enhance downslope drying in the lee of the Blue Ridge Mountains in western NC, resulting in RH of around 15% in some areas by peak afternoon heating. ...Please see www.spc.noaa.gov/fire for graphic product...Read more