METEOROLOGIST JEFF HABY
Low level moisture is assessed by examining
boundary layer dewpoints.
Severe thunderstorms are more likely when
dewpoint is 55 F or higher, all else being equal. Low dewpoint values
latent heat release and
significantly reduce the
Tornadoes are more likely when the
LCL is relatively low as
compared to relatively high. The depth of moisture in the lower troposphere and the rate of moisture
advection are also important to examine.
While a lack of moisture in the lower troposphere reduces the severe storm threat, a lack of moisture
in the middle troposphere is helpful to the severe storm threat if there is abundant moisture
in the lower troposphere.
Convective (potential) instability is present in this situation.
The advection of higher dew point values into the boundary layer can increase
instability in a severe
weather situation. This is often accomplished by advection from a warm ocean source.