SPC AC 041959 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Fri Apr 04 2025 Valid 042000Z - 051200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ARKLATEX TO SOUTHEAST MISSOURI... ...SUMMARY... Several clusters of severe storms are expected from central Texas across the ArkLaTex and into the lower Ohio Valley through tonight. The greatest threat for tornadoes, large hail and damaging winds will be from the ArkLaTex across western Arkansas into southeast Missouri, including potential for strong to potentially intense tornadoes. ...20z Update... Morning and early afternoon observations show the frontal zone gradually expanding north/northwest from the ArkLaTex to the mid MS and lower OH Valleys. As strong mid-level flow overlaps with the destabilizing air mass, several clusters of severe thunderstorms appear are ongoing and are likely to continue, with a risk for all hazards into tonight. Minor changes were made to the northern end of the outlook area, in accordance with the latest observations/guidance. ...ArkLaTex... The primary surface-based convective band, forming along and east of the surface front from northeast TX to southern AR should continue intensify with several supercells likely emerging and tracking through the MDT Risk Corridor. Additional, more isolated storms are possible within a pre-frontal confluence axis and across the warm sector this afternoon. The 18z SHV and LZK soundings show very favorable thermodynamic profiles, with considerable low-level hodograph curvature (ESRH 330-500 m2/s2) and deep-layer shear supportive for intense supercells. With observed and forecast STP of 5+, several tornadoes, some of which may be strong to intense appear likely into this evening. The primary limiting factor for higher probabilities continues to be the more meridional and front parallel flow near the baroclinic zone. The numerous storm interactions should favor upscale growth as a QLCS gradually emerges later this afternoon/evening. ...Lower OH and TN valley... Weak convective development within the broader warm sector has been noted early this afternoon across parts of TN and southern KY. Strong diurnal heating amid 70s F surface dewpoints and steep low-level lapse rates may allow these storms to slowly intensify through the afternoon. Displaced from the deeper ascent near the front, storm coverage and organization are expected to be somewhat less than farther southwest. Still, 40+ kt of effective shear with modestly large clockwise curved hodographs suggests some potential for supercellular activity, with a risk for damaging gusts, hail, and a couple tornadoes. The greater severe concern is expected later tonight as upscale growth from the convection over the MS Valley moves eastward. A QLCS with embedded supercellular elements appears likely across parts of western KY and TN into central KY and southern OH. Damaging gusts and tornadoes are expected. Given the robust destabilization now ongoing south of the warm front, have opted to expand the SLGT and the ENH farther east across KY and TN for a damaging wind and tornado threat. ...West TX... Model guidance continues to show a broad area of elevated convection developing after dark. Significant hail and some damaging winds are possible with elevated supercells tracking north from the Edwards Plateau toward the Red River tonight. ..Lyons.. 04/04/2025 .PREV DISCUSSION... /ISSUED 1129 AM CDT Fri Apr 04 2025/ ...ArkLaTex to the lower OH Valley through tonight... An amplified midlevel trough over the Southwest will move slowly eastward, while embedded/subtle speed maxima eject northeastward over the southern Plains. Additionally, large-scale ascent will be enhanced within the right-entrance region of the upper jet over the upper Midwest. At the surface, a baroclinic zone is expected to move northward today across AR/western TN/KY in response to a weak wave developing northeastward from northeast TX toward northwest AR this afternoon and southeast MO tonight. The depth of the cool air at LZK diminished substantially from 00z to 12z, which supports northward mixing of the front and warm sector this afternoon. Within the surface warm sector, a very moist air mass is in place with low 70s boundary-layer dewpoints beneath midlevel lapse rates of 7.5-8.5 C/km. Daytime heating in cloud breaks will contribute to MLCAPE of 2000-3000 J/kg and weakening convective inhibition by early-mid afternoon, when thunderstorm development is expected both along the surface front and in the open warm sector. Storm development will be most concentrated along the front where ascent will be focused and training storms are likely. More isolated storms will also be possible farther east in the warm sector from AR into western TN/KY by mid-late afternoon. Deep-layer vertical shear/hodograph length will be favorable for supercells, with substantial low-level hodograph curvature (effective SRH near or above 300 m2/s2, especially near and just southeast of the front in AR). Given the fairly strong low-level shear and a relatively moist environment in the low levels, supercells will be capable of producing a few strong (EF2-EF3) tornadoes this afternoon into this evening in the Moderate risk area. Otherwise, very large hail to baseball size and damaging gusts will be possible with the supercells and embedded/organized storm clusters training along the baroclinic zone. North of the front, organized storms will be capable of producing large hail and occasional damaging gusts. ...Edwards Plateau to north TX late tonight... Similar to the previous two nights, another round of elevated thunderstorms is expected near and after 06z from the Edwards Plateau into north TX and perhaps southeast OK. The storm environment will be favorable for both elevated supercells with very large hail and bowing clusters with some potential for damaging winds to the surface. CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
Category: Watches, Warnings, Advisories, & Hazards