Strong to severe thunderstorms appear possible across Alabama on Sunday during the afternoon and evening hours. At this time, damaging winds, hail, and tornadoes are possible, with the greatest threat along and south of I-20.
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Sat Apr 18 2020 Valid 191200Z - 201200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM THE SABINE RIVER EASTWARD INTO SOUTH CAROLINA... ...SUMMARY... Severe storms are likely Sunday from east Texas to South Carolina. The greatest threat appears to be from Louisiana to Georgia, with significant severe including tornadoes and damaging winds. Large hail is likely over much of the area as well. ...Synopsis... A progressive shortwave trough will move from the southern Plains into the lower MS Valley during the day, and will continue to the GA/SC/NC coast by Monday morning. The entire southeastern region will be under the influence of strong westerly winds aloft which will strengthen as the upper trough approaches. Southwesterly 850 mb winds will increase in response to the wave, reaching 50+ kt by 00Z from MS eastward to the coast. At the surface, low pressure will develop near the ArkLaTex by late afternoon as a warm front lifts north across the southeastern states, oriented roughly from southern AR into northern MS, AL, and GA at 18Z. Meanwhile, a cold front/dryline will develop over east TX. Across the warm sector, rich moisture with 65-70 F dewpoints will result in moderate instability. The low, likely associated with widespread convection, will translate eastward along the synoptic front overnight, reaching NC by 12Z Monday. ...Southeastern states... Substantial instability will already be in place Sunday morning from TX into the lower MS Valley, with rapid destabilization expected behind the warm front farther east into GA. Midlevel lapse rates aloft will be modestly steep, averaging 6.5 to 7.0 C/km. Early day storms related to warm advection will be present over AL and GA, and they will likely be elevated with perhaps a hail threat initially. As the air mass warms, a wind or tornado threat could develop in the vicinity of this activity as it continues east. To the west, storms are likely to be severe by 18Z near the Sabine Valley/ArkLaTex. Here, long hodographs but modest low-level SRH may result in cells capable of very large hail, and perhaps an eventual MCS with damaging-wind threat. A severe wind corridor may thus develop during the day across northern MS, AL, and GA. There is also a threat of daytime supercells, possibly tornadic, as the small capping inversion is eroded by early afternoon. During the evening and overnight, low-level shear will increase further, and models suggest southern AL into GA may be a favored area for tornadoes. Bows or isolated supercells are possible into SC early Monday morning as the relatively cooler air mass is destroyed by the warm front.