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SPC Apr 4, 2025 1630 UTC Day 1 Convective Outlook

5 months 1 week ago

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1129 AM CDT Fri Apr 04 2025 Valid 041630Z - 051200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FROM THE 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. ...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. ..Thompson/Jirak.. 04/04/2025 Read more