1PM Day 3 Convective Outlook for Wednesday, March 4. THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTH TX TO WESTERN AR
SUMMARY
Isolated to scattered severe thunderstorms may occur from mid-afternoon to evening Wednesday, centered on parts of north Texas to western Arkansas. Large hail should be the primary hazard.
Synopsis
A lower-amplitude shortwave impulse will gradually move from the central Great Plains to the Mid/Lower MO Valley, while a much more amplified trough digs across the West. Surface cyclone reflection will be nebulous in association with the lead wave, along a front that should be quasi-stationary on Wednesday afternoon/evening. The trailing portion of this front will advance north as a warm front in west TX, downstream of the amplified wave in the West.
Central TX to western AR
Initially steep mid-level lapse rates in conjunction with further boundary-layer moistening in the warm sector ahead of the front should yield a broad plume of moderate MLCAPE from 1000-2000 J/kg by mid-afternoon across much of central/eastern TX into eastern OK. Weak mid-level height falls trailing from the NE/KS shortwave trough and adequate convergence along the quasi-stationary should support increasing convective development towards late afternoon. Deep-layer shear with southern extent in TX will be weak owing to the compactness of the jetlet attendant to the aforementioned trough. Effective bulk shear should commonly hold around 15-25 kts. Shear values will increase north of the Red River, but remain modest relative to early spring climo. Transient supercell structures that evolve into mainly multicell clusters are the anticipated modes. At least isolated severe hail is anticipated, primarily in the mid-afternoon to early evening, before organized cellular structures diminish. The paucity of cyclogenesis/stronger deep-layer shear and modest large-scale ascent may help marginalize the overall severe threat.
Ozarks to the Lower OH Valley
Multiple rounds of convective potential are expected through the period. Elevated storms should be ongoing on Wednesday morning and will help define the northern extent of any surface-based destabilization into the Mid-MS/Lower OH Valleys. The degree of warm-sector insolation is questionable with potential for repeated convective regeneration ahead of the KS/NE shortwave trough. Conditionally, moderately favorable deep-layer shear could support a few supercells and/or linear clusters near the quasi-stationary front. As such, a swath of low severe probabilities remains warranted, mainly from mid-afternoon into the evening Wednesday.