SPC Mar 13, 2025 1730 UTC Day 2 Convective Outlook
SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1228 PM CDT Thu Mar 13 2025 Valid 141200Z - 151200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS IN SOUTHEAST IA...EASTERN MO...IL...FAR WESTERN KY/NORTHWEST TN/NORTHEAST AR... ...SUMMARY... A regional outbreak of severe storms is likely over the Lower/Mid-Missouri/Mississippi Valleys and Lower Ohio Valley late Friday afternoon into Saturday morning. Tornadoes, several of which could be strong, widespread damaging winds with gusts from 70 to 90 mph, and scattered large hail up to baseball size will be possible. ...Synopsis... Primary change this outlook cycle has been to mainly expand MRGL/SLGT/ENH damaging wind probabilities west to north in the Lower/Mid-MO Valley. No change to the level 4/MDT risk with greater uncertainty over the southern extent of widespread damaging wind potential into the Mid-South, but where strong tornado potential persists. ...Lower/Mid-MO, Mid-MS, and Lower OH Valleys... A powerful shortwave trough will amplify from the southern High Plains into the Upper MS Valley. This will induce further deepening of an intense surface cyclone across the central Great Plains to the Mid-MO Valley. Initial surface-based thunderstorm development is expected by early to mid-afternoon along the northwest periphery of a modified moisture plume emanating north from the South-Central States. Well-mixed, inverted-v thermodynamic profiles will support downward momentum transport in the left-exit region of an intense 700-mb jet curling across the Ozarks to the Mid-MS Valley. This should yield a rapidly progressing QLCS from the Lower to Mid-MO Valley across much of the Mid-MS Valley into Friday evening, with semi-discrete supercells trailing to the southeast portion of the convective plume. Given the fast low to mid-level flow regime, embedded gusts from 60-80 kts should be common along with a QLCS/embedded supercell tornado threat. The latter will be greater with southeast extent where a ribbon of somewhat richer low-level moisture should reach the Mid-MS Valley. Convection should tend to weaken overnight more quickly on the north end of the outlook area as it outpaces the confined surface-based instability plume. But some overnight damaging wind/tornado potential should persist across the Lower OH Valley. ...Mid-South to Lower MS and TN Valleys... South of the QLCS regime, forecast confidence in sustaining deep convection lowers with southern extent. Persistent southerly low-level flow will bring mid to upper 60s F dewpoints northward across the region by Friday evening/night. Forecast soundings indicate rather favorable thermodynamic and kinematic profiles, conditionally supporting intense and long-track supercells. Neutral to weak mid-level height falls are expected, with the strong low-level jet tending to shift north/east of the Lower MS Valley overnight. This suggests forcing mechanisms will be modest, which is likely behind guidance spread with the depiction of deep convection during the evening and overnight. A few broken to semi-discrete supercells appear most probable in the Mid-South, posing a risk for strong tornadoes, significant damaging wind gusts, and very large hail. These threats appear more conditional farther south/east in the Lower MS and TN Valleys. ..Grams.. 03/13/2025
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