Severe Storm Outlook Narrative (AC)
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Issued by NWS
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313 ACUS01 KWNS 192001 SWODY1 SPC AC 192000 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Sun May 19 2024 Valid 192000Z - 201200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF OK... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE PLAINS AND SOUTHEAST FLORIDA... ...SUMMARY... Numerous severe thunderstorms capable of widespread damaging winds and giant hail are expected this afternoon and evening across portions of Kansas and northern Oklahoma. Gusts of 75-100 mph are possible, along with very large hail and a few tornadoes. ...20z Update... No consequential changes to forecast reasoning and current Day 1 Outlook. Main severe risk as depicted by MDT/ENH risks appears to be steadily unfolding generally as expected, including intense storm development along the boundary in north-central Kansas, with higher-based storms also steadily increasing across southeast Colorado and the Oklahoma/Texas Panhandles. Semi-discrete supercells are still expected before cell mergers/aggregating cold pools lead to potentially significant severe wind potential across southwest/central Kansas and nearby northern Oklahoma, which is consistent with latest WoFS forecasts. ..Guyer.. 05/19/2024 .PREV DISCUSSION... /ISSUED 1120 AM CDT Sun May 19 2024/ ...KS/OK... Morning water vapor imagery shows a shortwave trough over northern AZ. This feature is expected to accelerate eastward this afternoon, with an associated mid/upper level jet max nosing into the central High Plains. This will lead to scattered high-based thunderstorms over southeast CO by mid-afternoon, capable of locally gusty winds and hail. As this activity builds eastward across the dryline, rapid intensification of supercell storms is expected. Forecast soundings show a relatively deep boundary-layer, but large CAPE values and dry-adiabatic mid-level lapse rates. Deep-layer shear profiles will promote rotating storms capable of very large hail, damaging winds, and a tornado or two across southwest KS and any more isolated cells that form southward along the dryline into western Oklahoma. As this activity moves eastward, congealing outflows will likely result in a fast-moving QLCS capable of widespread significant wind damage for a few hours. It remains unclear how far east this threat will persist, but given current model guidance, will not change the ongoing bounds of the ENH/MDT risk areas in eastern KS. ...Eastern FL... A surface cold front is sagging southward across the central FL peninsula today. Along and ahead of the front, very warm/moist low-level conditions persist with dewpoints in the low-mid 70s and strong daytime heating occurring. It appears likely that at least scattered thunderstorms will form near/along the east-coast sea breeze later this afternoon. Any storm that can intensify before it moves offshore would potentially acquire supercell characteristics and pose a risk of large hail and damaging wind gusts. See mesoscale discussion #829 for further details. ...SD/NE/Northeast CO... Strong heating is occurring across much of western SD/NE, where southerly low-level winds are helping to transport 50s dewpoints in the region. A weak shortwave trough currently over WY will approach the region by mid-afternoon, helping to initiate scattered thunderstorms from the Black Hills region southward into western NE and northeast CO. These storms will be relatively high-based, but in an environment of sufficient vertical shear to promote organized multicell or supercell structures capable of damaging winds and hail. Storms will persist through much of the evening and spread into central SD/NE before weakening. $$