Justin Lane of the NWS in Greer, SC now presenting on tornado outbreaks associated with landfalling tropical cyclones (LTCs)
Majority of tornado outbreaks in LTCs occur with mid-level drying. Best helicity n the NE quadrant. There is also a marked increase in vertical shear over land.
Highest tornado probability about 240 km northeast of center of the storm.
Ivan produced 114 tornadoes in two days across the SE US... including 25 in Georgia. All in the right front quadrant. Second largest STC outbreak on record. Almost all tornadoes to the east and northeast of Alabama.
Largest tornado outbreak in GA recorded history.
Top four LTC tornado producers:
1. Allen
2. Andrew
3. Beryl
4. Beulah
Parameters for tornadoes in an LTC situation:
CAPE leaning toward moderate instability (850-900 CAPE)
Mid level dry air
High SRH (250-350)
Low LCL heights
Weak baroclinic bountary
Mid level dry air means: stepper mid-level lapse rates. Colder FFD/enhanced surface baroclinity... meaning low level mesocyclogenesis.
Warm RFD processes (related to low LCL heights) may be a necessary condition for tornadogenesis.
After watching this presentation I realize how fortunate we were not to have tornadoes with Ivan in Alabama. Guess we really have to look out a hurricane with landfall over Louisiana or Mississippi!
Good to see JOHN WALKER here along with many others from the University of South Alabama.
More to come...
Majority of tornado outbreaks in LTCs occur with mid-level drying. Best helicity n the NE quadrant. There is also a marked increase in vertical shear over land.
Highest tornado probability about 240 km northeast of center of the storm.
Ivan produced 114 tornadoes in two days across the SE US... including 25 in Georgia. All in the right front quadrant. Second largest STC outbreak on record. Almost all tornadoes to the east and northeast of Alabama.
Largest tornado outbreak in GA recorded history.
Top four LTC tornado producers:
1. Allen
2. Andrew
3. Beryl
4. Beulah
Parameters for tornadoes in an LTC situation:
CAPE leaning toward moderate instability (850-900 CAPE)
Mid level dry air
High SRH (250-350)
Low LCL heights
Weak baroclinic bountary
Mid level dry air means: stepper mid-level lapse rates. Colder FFD/enhanced surface baroclinity... meaning low level mesocyclogenesis.
Warm RFD processes (related to low LCL heights) may be a necessary condition for tornadogenesis.
After watching this presentation I realize how fortunate we were not to have tornadoes with Ivan in Alabama. Guess we really have to look out a hurricane with landfall over Louisiana or Mississippi!
Good to see JOHN WALKER here along with many others from the University of South Alabama.
More to come...
on March 5, 2005, 9:44 am
Rob Howard currently speaking on data that the University of Louisiana at Monroe collected when Hurricane Frances made landfall.
Definitely some interesting stuff and look foward to listening to the rest of the speakers today.
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