The low level jet is a high speed return of warm and moist air from the south or southeast; moisture
source is the Gulf of Mexico
Most common and intense over the Plains states and Southeast states
The low level jet occurs in the warm sector of a developing mid-latitude cyclone
in the Central and Eastern U.S.; occurs generally ahead of the cold front boundary
Intensity of low level jet is increased due to
temperature gradient between cooler high elevations in the
high plains compared to warmer East Great Plains at night. Can also intensify by the warm sector of
a mid-latitude cyclone being east of the cold sector.
Low level jet adds heat, mass and momentum to developing thunderstorm and produces low level speed and
directional shear (results in very high Helicity values)
Produces abundant WAA (warm air advection) that may
break a weak to moderate cap. WAA produces broad
synoptic scale uplift
Strongest low level jet winds are generally at the top of
Planetary Boundary Layer due to less
friction than at the surface
Advection may well be over 65 miles per hour
EXAMPLE:
![[ Low Level Jet ]](../gif/llj.gif)
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