METEOROLOGIST JEFF HABY
1. What is MPL?
The MPL (Maximum Parcel Level) is the maximum height a thunderstorm will build in the atmosphere using
pure buoyancy theory. The MPL is higher than the
EL (Equilibrium Level) since updraft momentum carries the updraft
higher as the updraft decelerates.
2. How is MPL determined?
First, the amount of
CAPE is determined between the
Level of Free Convection and the Equilibrium Level. Once this
area of CAPE is found, an equal area of negative CAPE is filled in above the EL. The top of this area of
negative CAPE is the MPL.
The sounding below has an EL of 159 mb and a MPL of 89 mb. The area of negative
CAPE (parcel colder than environment) between 159 and 89 mb is equal to the amount of positive
CAPE between 809 mb and 159 mb. The negative CAPE is in a more compressed vertical distance due to
the intense stability encountered as the tropopause is entered.
3. Operational significance of MPL:
UPDRAFT: A MPL much higher than that EL indicates an intense updraft.
a. Both the CAPE and negative CAPE calculated from pure buoyancy theory do not take into consideration the
mass of water (in all three phases) in the air.
Mass reduces CAPE while enhancing negative CAPE.