The high SB CAPE on the SPC meso page is probably being shown due to a few stations with anomalously high Td, namely KMTN (Martin St Airport), KNHK (NAS Patuxent) and KNAK (Naval Academy). Their proximity to the water may be representative of the local conditions near the observation site but it's similar to how DCA can torch if the winds flip to the SW or back to the SE off the water. The ML CAPE values are more realistic, and even then might be a ~100 j/kg too high because they are incorporating the above stations.