SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1042 AM CST Sat Feb 15 2025 Valid 151630Z - 161200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE LOWER MISSISSIPPI VALLEY...MID-SOUTH...AND SOUTHEAST... ...SUMMARY... Severe thunderstorms are expected from parts of far east Texas into much of the lower Mississippi Valley and Southeast this afternoon through the overnight. Several tornadoes and scattered to numerous damaging wind gusts should be the primary threats. A few strong tornadoes are also possible. ...Synopsis... Water-vapor imagery this morning shows a potent mid-level trough over the Permian Basin pivoting east through the base of a larger scale trough forecast to shift from the Rockies east into the MS Valley. A complex surface pattern is evident with a low over OK with an accompanying trailing cold front, while a maritime boundary/residual frontal zone is draped over east TX arcing northeastward into the MS/AR/TN border region and then southeastward into the northeast Gulf of America. As the cyclone consolidates and moves eastward this afternoon into AR, the aforementioned composite boundary will advance northward as a warm front into the Mid South and towards the southern Appalachians late. The cold front is forecast to push southeast and overtake the western portion of the warm sector late today into tonight and provide a focus for numerous developing thunderstorms in the form of a squall line. ...East Texas into the Lower Mississippi Valley and Southeast... Strong low-level warm advection has resulted in scattered showers/thunderstorms mainly north of the warm front from AR east into TN. Southerly flow will promote poleward moist advection with 60s deg F dewpoints spreading north across the lower MS Valley into parts of the Mid South. The destabilizing warm sector will remain capped during the day before stronger large-scale ascent approaching from the west results in a extensive thunderstorm development from the Ark-La-Tex northeast into eastern AR/western TN/KY. Filtered daytime heating and low-level moistening will aid in the development of around 500-1000 J/kg of MLCAPE by mid to late afternoon. Surface-based thunderstorms are forecast to develop by mid afternoon near or on the cold front from east TX into the Mid South. Only a narrow window of opportunity for supercells will likely occur before rapid upscale growth into an extensive squall line by early evening. Strong 0-3 km shear, aided by a 45-55+ kt low-level jet, will easily aid updraft rotation and organized severe thunderstorms. Ample low-level shear will support a threat for several line-embedded tornadoes beginning from late this afternoon through early Sunday morning. The potential for supercells ahead of the line will likely remain limited but will be greatest perhaps over the southern parts of MS/AL tonight. However, if cellular structures are maintained in the large-scale thunderstorm band, an accompanying risk for tornadoes may focus there and with any bowing inflections in the line. Given the low CAPE/high shear setup with relatively modest lapse rates and moist profiles, scattered to numerous severe/damaging winds will likely occur with the squall line as it matures. Have increased damaging wind probabilities from parts of MS into AL where confidence is greatest for damaging gusts later tonight. A continued tornado/damaging wind risk will become increasingly confined to the Gulf coastal plain late tonight into the early Sunday morning hours. ..Smith/Supinie.. 02/15/2025
