Our first high risk of the year

Today SPC has issued a high risk (for tornadoes) for the Ohio river valley region. Part of the risk for tornadoes hinges on just how much low-level helicity there will be, and low-level helicity (at least the storm-relative part, SRH) depends heavily on storm motions. If storms move more easterly, they will have very high amounts of SRH to work with, and likely produce tornadoes. If they move more northeasterly, SRH will be correspondingly lower.