1PM Day 1 Convective Outlook for Sunday, March 1. THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF CENTRAL OKLAHOMA
SUMMARY
A few instances of severe hail are likely across central Oklahoma into the evening hours. An instance or two of hail or damaging gusts may still occur over southern parts of the Florida Peninsula this afternoon.
20Z Update
The primary change made to this outlook was to add a Slight risk to portions of OK, while also expanding the Marginal risk to the south and west across southern portions of the state. Confidence is increasing for the initiation of a few supercell thunderstorms across central OK this afternoon ahead of a frontal boundary. Current OK Mesonet surface observations depict a tongue of 59-60 F surface dewpoints, which are advecting northward across the southern portions of the state, toward the OKC metropolitan area. At least some mid-level clouds persist over and around the metro, suggesting that low-level moisture may not appreciably mix out through the remainder of the afternoon. As such, the current moisture profile, beneath 6.5-7 C/km mid-level lapse rates, will yield thin surface-based buoyancy profiles, with 1000/500 ML/SBCAPE by afternoon peak heating. Current INX/TLX VAD profiles depict hodographs with modest 0-3 km curvature, and RAP forecast soundings suggest that elongated mid-level hodographs should persist into the evening hours, resulting in appreciable deep-layer shear for supercell structures. While buoyancy will be relatively meager overall, a few hail reports at least in the 1-2 inch diameter range appears plausible this afternoon and evening.
Otherwise, the previous forecast remains on track, with an instance or two of hail/strong wind gusts possible with thunderstorms developing off of sea-breeze boundaries over far southern FL over the next few hours.
Oklahoma
A mid-level disturbance near the CO-KS border this morning will quickly move east to the Ozarks by mid evening. Glancing large-scale ascent associated with this feature and associated low-level warm/moist advection will contribute to isolated to scattered thunderstorms later this afternoon and into the evening from near the Red River into the Ozarks. A stalled cold front paralleling the I-44 corridor will likely serve as a focus for thunderstorm development as an axis of weak buoyancy develops within a narrow moist plume (50s deg F surface dewpoints) extending from north TX into central OK. Forecast soundings show elongated hodographs and upwards of 1000 J/kg MUCAPE, supporting an environment potentially capable of a couple stronger storms that could yield a risk for hail/wind during the 22-04z period.
South Florida
A weak mid-level trough over the eastern Gulf will move east-southeastward across the FL Peninsula by early evening. Accompanying weak ascent with this upper feature and differential heating near a frontolytic boundary will support isolated to widely scattered thunderstorms developing this afternoon across parts of south FL. Around 1000 J/kg of MLCAPE is probable by early to mid afternoon. Weak flow in the surface-3km layer will limit overall hodograph length beneath 50-kt westerly flow at 300 mb. A couple of the stronger thunderstorms may pose a risk for marginally severe hail and perhaps gusts approaching 60 mph.