| 15% |
| 30% |
| Thunderstorms |
| 1: Marginal |
| 2: Slight |
| 3: Enhanced |
| 4: Moderate |
| 5: High |
| 2% |
| 5% |
| 10% |
| 15% |
| 30% |
| 45% |
| 60% |
 | Sig |
| 5% |
| 15% |
| 30% |
| 45% |
| 60% |
| Sig |
| 5% |
| 15% |
| 30% |
| 45% |
| 60% |
| Sig |
000 ACUS01 KWNS 290545 SWODY1 SPC AC 290544 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1244 AM CDT Mon Apr 29 2024 Valid 291200Z - 301200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF SOUTH TEXAS INTO THE LOWER MISSISSIPPI VALLEY... ...SUMMARY... Marginally severe wind gusts and hail will be possible today from parts of south Texas northeastward into the lower Mississippi Valley. ...South Texas/Lower Mississippi Valley... At the start of the period, a linear MCS will be ongoing from the southeast Texas Coast northeastward into the lower Mississippi Valley. The strongest part of the MCS is expected to be in southern Louisiana during the first three hours of the period, from 12Z to 15Z. The wind-damage threat is expected to remain isolated as it moves southeastward across the Louisiana Coast this morning. A marginal wind-damage threat is also expected further northeast into south-central Mississippi from this morning into early afternoon. However, instability should remain very weak, limiting the severe threat potential. Further southwest into south Texas, a moist and unstable airmass will be in place from the Rio Grande River eastward to the middle Texas Coast. Along the northern edge of this moist airmass, isolated storms may develop this afternoon. Moderate deep-layer shear should be enough to support a marginal severe threat. However, any threat should be very isolated. ..Broyles/Thornton.. 04/29/2024 $$
000 ACUS02 KWNS 290611 SWODY2 SPC AC 290610 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0110 AM CDT Mon Apr 29 2024 Valid 301200Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR EASTERN NE...WESTERN IA...NORTHWEST MO...EASTERN KS...SOUTHEAST SD...SOUTHWEST MN... ...SUMMARY... Severe thunderstorms will be possible on Tuesday from parts of the mid/upper Mississippi Valley into the central/southern Plains. The greatest threat is expected from eastern Nebraska into parts of western Iowa and southwest Minnesota, with a risk of very large hail, severe wind gusts, and a few tornadoes. ...Synopsis... An amplified mid/upper-level shortwave trough is forecast to move eastward from the northern Rockies into parts of the northern Plains on Tuesday, as an attendant strong mid/upper-level jet overspreads the central Plains. A surface wave is forecast to move from the central Plains toward the upper MS Valley, with a separate low expected to largely remain in place across the southern High Plains. ...Upper MS Valley into the southern Plains... An active severe weather day appears possible from eastern NE/southeast SD into western IA/southwest MN, though uncertainty remains regarding the quality of moisture return and primary storm mode. Modest low-level moisture will stream northward through the day from the southern Plains into the central Plains and upper MS Valley, in response to the approaching shortwave trough. While the richest moisture will likely remain displaced southward of the shortwave track, 50s to near 60F dewpoints could spread as far north as eastern NE/western IA and southern MN by Tuesday afternoon. This moistening beneath steep midlevel lapse rates will support diurnal destabilization, with peak MLCAPE ranging from around 500 J/kg across southern MN to greater than 1500 J/kg across the central/southern Plains. Thunderstorm development is expected along a cold front by mid afternoon across northeast NE into southeast SD, with somewhat later initiation possible southward into southeast NE/northeast KS, as strong ascent overspreads the region. Quick evolution into supercells will be possible due to very favorable deep-layer shear, though some evolution toward a linear or cluster mode will be possible with time as storms move eastward. Any persistent supercells will pose a threat of potentially very large hail (greater than 2 inches in diameter). Any notable upscale growth could also be accompanied by severe wind gusts (potentially in excess of 75 mph), especially in areas where stronger heating occurs prior to storm arrival. Some tornado threat would also accompany any stronger supercells, though the magnitude of the tornado risk will be dependent on the quality of low-level moisture return, which remains uncertain at this time. Greater severe probabilities may eventually be needed once confidence increases regarding moisture and primary storm mode. More isolated development appears possible into the southern Plains, where a supercell or two could develop with a threat of hail and localized severe gusts. ...Parts of PA into central NY... A weakening upper-level trough will move across parts of the OH Valley on Tuesday. While the surface pattern will be rather nebulous, modest low-level moisture will support at least weak diurnal destabilization. Modestly supportive deep-layer shear could support a few strong storms during the afternoon from parts of PA into central NY. No probabilities were added due to uncertainty regarding the magnitude of destabilization, but some isolated severe threat could eventually evolve depending on trends regarding the extent of heating and low-level moisture across the region. ..Dean.. 04/29/2024 $$
000 ACUS03 KWNS 290731 SWODY3 SPC AC 290730 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 AM CDT Mon Apr 29 2024 Valid 011200Z - 021200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE CENTRAL/SOUTHERN GREAT PLAINS... ...SUMMARY... Scattered severe thunderstorms will be possible across parts of the central and southern Plains on Wednesday. A few tornadoes will be possible (including potential for a strong tornado), in addition to large to very large hail and damaging winds. ...Synopsis... In the wake of a strong shortwave trough moving toward the upper Great Lakes, a broad upper trough is forecast to move slowly eastward toward the central CONUS on Wednesday. A surface low is forecast to deepen across the south-central High Plains, with rich low-level moisture expected to stream northward across the warm sector. A dryline will extend south of the low during the afternoon, while a warm front will move northward toward the KS/NE border. Farther south, a secondary mid/upper-level jet maximum may overspread parts of west/southwest TX. ...Parts of the central/southern Plains... A favorable conditional environment for severe thunderstorms will likely develop across parts of the warm sector on Wednesday, and supercells capable of all severe hazards will be possible. Storm coverage and evolution remain uncertain, however. Steep midlevel lapse rates atop rich low-level moisture (with dewpoints in the mid 60s to near 70 F) will support strong destabilization along/east of the dryline and south of the warm front by Wednesday afternoon. Mid/upper-level flow will remain relatively modest across most of the warm sector, but veering wind profiles will support effective shear generally above 40 kt, sufficient for supercell development in the presence of strong instability. The primary uncertainty is the coverage and location of storm diurnal storm development, with only subtle vorticity maxima expected to overspread the warm sector. However, at least isolated storm development will be possible near the dryline, with increasing storm coverage expected near the warm front by afternoon/evening. Any sustained supercells will pose a threat of very large hail and tornadoes, with a strong tornado possible as the low-level jet increases into the evening. MCS development will also be possible Wednesday evening near/north of the warm front, aided by a strong low-level jet. Farther south, the subtle subtropical shortwave trough could support a secondary maximum of storm coverage from southwest into central TX, though this scenario is more uncertain. The Marginal Risk has been expanded across much of TX, with some potential for initial isolated supercells to evolve into one or more storm clusters into Wednesday evening as they move eastward. ..Dean.. 04/29/2024 $$
000 ACUS48 KWNS 290845 SWOD48 SPC AC 290844 Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0344 AM CDT Mon Apr 29 2024 Valid 021200Z - 071200Z ...DISCUSSION... ...D4/Thursday - Southern Plains into the mid/upper Mississippi Valley... Extensive convection appears likely from the southern Plains northeastward into the mid/upper MS Valley on Thursday, as a relatively deep upper trough continues to impinge upon a broad and moist warm sector. Deep-layer shear will be sufficient to support organized convection, and pockets of severe potential are likely to evolve within this regime. However, most guidance suggests that one or more MCSs will be ongoing Thursday morning, with widespread cloudiness and precipitation possible across much of the warm sector. Storm redevelopment will be possible as a cold front moves into the region, but magnitude of instability and potential influence of convective outflow remain too uncertain to delineate a 15% area. ...D5/Friday into D8/Monday... Predictability regarding the synoptic pattern wanes rather quickly by the weekend. In general, a cold front is expected to move southeastward on D5/Friday and then stall from the southern Plains into the lower MS Valley. Rich low-level moisture will support daily destabilization along/south of the front. However, potential for either storm development across TX or for moisture/instability to be drawn northward into a larger portion of the Plains remains quite uncertain into early next week. ..Dean.. 04/29/2024
