1PM Day 1 Convective Outlook for Friday, February 13. THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHERN PLAINS
SUMMARY
Isolated strong to severe thunderstorms may produce occasional hail and gusty winds this evening into the overnight hours across parts of the southern Plains.
20Z Update
No changes needed to the ongoing forecast.
Recent satellite imagery continues to show a shortwave trough extending from the western Great Basin to off the central Baja Peninsula. A lead vorticity maximum is ejecting northeastward ahead of the main shortwave across northern Mexico, and ascent attendant to this feature will likely begin interacting with the northwestern periphery of the returning low-level moisture this evening. As mentioned in the previous discussion, this interaction should support isolated thunderstorms across northwest TX and southwest OK. Isolated hail is the primary risk with this activity.
Thunderstorm coverage is expected to expand tonight from northwest TX/southwest OK into much of west TX as persistent large-scale ascent is augmented by a strengthening low-level jet and associated warm-air advection. A few stronger storms and/or clusters remain possible overnight, with perhaps even an embedded supercell. A transition to a mix of hail/wind potential is still expected during the overnight hours as the convective mode trends more linear. Isolated strong to severe storms will remain possible across OK overnight, supported by strengthening warm-air advection, strong shear, and modest buoyancy.
Southern Plains
An upper trough over Baja California late this morning will move eastward across the Southwest/northern Mexico into the southern Rockies by early Saturday morning. Gradually strengthening low-level flow will continue to advect somewhat richer moisture northwestward from the TX Hill Country (mostly 50s surface dewpoints) into parts of west TX and western/central OK through the period. Modestly steepened mid-level lapse rates present will support around 500-1000 J/kg MUCAPE by this evening across the southern High Plains. Various NAM/RAP forecast soundings show strong effective bulk shear (around 50-70 kt) this evening/overnight as southwesterly mid/upper-level flow strengthens with the approach of the upper trough, which will likely support thunderstorm organization.
Isolated thunderstorms should initially develop on the northwest periphery of the low-level moisture return over parts of northwest TX and vicinity late this afternoon/early evening with some hail threat. As large-scale ascent associated with the upper trough approaches the southern High Plains later this evening, a more extensive southwest to northeast corridor of convection is expected. One or more clusters may eventually evolve into linear bands and develop east-northeastward along/near an eastward-moving Pacific front.
One of these linear clusters with perhaps embedded supercells seems likely to occur early Saturday morning (after 14/06Z) from parts of west into northwest TX as stronger forcing for ascent overspreads this region. Mainly an isolated severe hail risk with the strongest updrafts this afternoon/evening should transition to a mix of hail/wind potential during the overnight hours as the convective mode becomes more linear. Strengthening low-level warm-air advection over OK tonight will favor primarily elevated strong to locally severe thunderstorms capable of occasional hail, perhaps extending as far north as southern KS during the pre-dawn hours Saturday.