Severe Storm Outlook Narrative (AC)
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Issued by NWS
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900 ACUS01 KWNS 280600 SWODY1 SPC AC 280559 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Tue May 28 2024 Valid 281200Z - 291200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR NORTHWEST INTO NORTH/CENTRAL TEXAS... ...SUMMARY... Widespread strong to severe storms are expected over much of Texas later today, with potential for significant damaging wind and areas of very large hail. ...Southern Plains... Rich low-level moisture and strong to extreme instability (MLCAPE of 3000-5000 J/kg) will be in place at the start of the forecast period across much of Texas, to the south of a surface front draped from northwest into east TX, and to the east of a dryline across southwest TX. Strong elevated buoyancy will extend north of the boundary into parts of OK. Elevated convection will likely be ongoing this morning, mainly near/north of the front. Large hail and locally gusty winds will be possible with these elevated storms. Evolution of the morning convection will be crucial in determining the magnitude and location of the greatest severe threat later in the day. It is possible that morning storms will grow upscale and move southeastward along the instability gradient, which would push the outflow-reinforced front southward through the day. Any upscale growth during the morning could result in an MCS posing a risk of severe wind gusts potentially into parts of northeast TX and northwest LA. If outflow does not become too expansive during the morning, then intense storm development will be possible this afternoon in the vicinity of the dryline across west TX. While midlevel flow will not be very strong, substantial veering with height will support sufficient effective shear for supercell development. Very large hail (greater than 2 inches in diameter) and localized severe gusts could accompany any supercell. Some tornado threat could also evolve, especially near the dryline/front intersection, as well as with any supercell that survives into the richer low-level moisture east of the dryline. A southeastward-moving MCS could evolve out of initial supercell development, which would pose a threat of very damaging wind gusts (potentially in excess of 80 mph) if the initially very favorable thermodynamic environment is not disrupted by early-day outflow. If convective outflow surges across much of TX relatively early in the day, then potential for a longer-lived and organized MCS will be reduced. However, even in this scenario, a few intense cells/clusters capable of very large hail and significant severe gusts will still be possible. At this time, the area of greatest confidence in higher-end severe potential lies roughly from the TX Big Country region into parts of central/north TX. The southeastward and westward extent of the greater threat will be determined in part by the evolution of the outflow-reinforced front through the day. ...Eastern OR into northern ID into western MT... A strong mid/upper-level shortwave trough will move eastward across the Pacific Northwest later today into tonight. While moisture will be limited ahead of this system, steep low/midlevel lapse rates will support modest destabilization, and scattered thunderstorm development will be possible this afternoon into the evening. Stronger flow aloft will be displaced westward of storm development, but deep-layer shear may still be sufficient to support a few stronger cells/clusters capable of isolated severe gusts and perhaps some hail. ...Southern WI into Northern IL/IN... A few strong storms will be possible this afternoon into the early evening from southern WI into parts of northern IL/IN. While low-level moisture and deep-layer shear will generally be modest, cold temperatures aloft will support MLCAPE rising into the 500-1000 J/kg range. A couple stronger multicells could become capable of producing hail. Strong wind gusts could also accompany the strongest storms, especially where greater pre-storm heating can occur through the day. ..Dean/Moore.. 05/28/2024 $$