Valid 311630Z – 011200Z
…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS
NORTHERN/EASTERN KY TO CENTRAL/SOUTHERN WV…
Isolated, marginally severe thunderstorms are possible across parts
of the Ohio Valley to central Applachians between 2 to 8 PM EDT.
…Ohio Valley to central Appalachians…
Robust boundary-layer heating near a weakly convergent
quasi-stationary front, ahead of a decaying mid-level impulse,
should aid in isolated thunderstorms forming by mid afternoon. A
confined corridor of modest buoyancy should develop, characterized
by MLCAPE of 1000-1500 J/kg. While low-level winds will be weak, a
belt of 25-30 kt 500-mb southwesterlies should support transient
updraft rotation in a few cells. This may yield locally strong wind
gusts along with marginally severe hail.
…Northern Nebraska to southern/eastern South Dakota…
While overall forcing for ascent will be limited, sufficient
moist/convergence could influence isolated thunderstorm development
near a weak surface/boundary across northern Nebraska/southern South
Dakota. If storms develop, a severe storm or two cannot be entirely
ruled out given adequate buoyancy and moderately strong
northwesterly flow aloft. Storms are a bit more likely to develop
later tonight across eastern South Dakota with increasing warm
advection, although hail potential will tend to be limited by modest
mid-level lapse rates. Overall scenario across the region currently
appears too marginal/uncertain to warrant severe probabilities.
An isolated storm or two could develop over/near the mountains of
southeast Arizona this afternoon and drift generally westward.
However, storm organization should be limited by weaker mid-level
winds, while the strongest updrafts should be relegated to south of
the international border. As such, severe wind probabilities do not