SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0938 AM CST Sun Jan 05 2025 Valid 051630Z - 061200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE LOWER MISSISSIPPI VALLEY... ...SUMMARY... Severe thunderstorms are expected this afternoon and evening from the Sabine River Valley into the Mid-South and central Gulf Coast states. Tornadoes and scattered severe/damaging winds should be the primary threats. A couple of strong tornadoes may also occur. ...Synopsis... Water-vapor imagery this morning shows a mid- to upper-level trough over the central U.S. A powerful mid-level shortwave trough will move through the base of the larger-scale trough over OK and move into the lower OH Valley/Mid South with an accompanying 100-kt 500mb speed max over the central Gulf Coast states by early Monday morning. In the low levels, a cyclone over northeast OK will develop east into the KY/TN border region late. An accompanying cold front over the southern Great Plains this morning will sweep southeastward into the lower MS Valley by late afternoon before moving into the southern Appalachians and FL Panhandle by daybreak Monday. ...East Texas into the Mid-South and central Gulf Coast states... A weak thunderstorm band this morning from western AR into northeast TX has developed immediately ahead of the front in response to intensifying large-scale ascent and strong low-level warm/moist advection. Despite a pronounced capping inversion noted on the 12z Shreveport, LA raob, additional moistening/destabilization and ascent will promote additional storm development late this morning into the afternoon. Model guidance shows only weak elevated instability over northeast AR into western TN, but larger buoyancy will exist over southern AR/LA/east TX where 500-1000 J/kg MLCAPE is expected. Model forecast soundings show enlarged hodographs across the surface-based warm sector with 0-1 km SRH generally in the 250-500 m2/s2 range. It appears a mix of pre-frontal and frontal thunderstorm activity will evolve late this morning through the early evening. The stronger and more persistent updrafts ahead of the front will likely become supercellular and pose a risk for tornadoes, including the possibility for strong tornadoes. Damaging gusts and perhaps some tornado risk will likely evolve with the frontal convection (QLCS) as it gradually intensifies this afternoon and likely persists across the coastal plain through tonight. Have increased low-severe probabilities farther east into southeast AL where model guidance shows weak destabilization prior to frontal passage late tonight. ..Smith/Weinman.. 01/05/2025