Hurricane Charley Aug. 2004

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Hurricane CharleyAug. 2004

• Rapid Intensification and Trough Interaction
• By Andy Latto

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Objectives

• What is trough interaction?
• EFC Theory (Eddy Flux Convergence)
• Potential Vorticity PV
• Models incorporating and forecasting trough
  interaction.

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Trough Interaction

• Dynamical and thermodynamic interaction between a
  hurricane vortex and upper level trough.
• Trough needs to be close but not too close to
  storm for positive interaction (lt 400 to 1000km)
• Trough acts as a catalyst and storm responds
  positively or negatively.

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Trough Interaction Theories

• EFC
• PV 2 Added heating (omega) aloft forces a
  stronger thermal gradient below.
• Enhanced outflow due to increase in upper level
  flow.
• Potential Vorticity According to QG Theory,
  added positive vorticity advection increasing
  with height causes low level ascent.

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Hurricane Charley
August 2004
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Hurricane Charley

• Rapid Intensification -24 hPa in 6 hours

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Models Used

• GFDL

• AVN

• Uses Axi-symmetic vortex
• Adds in asymmetric vortex
• Triple-nested movable mesh
• 1/12 degree resolution
• Good for hurricane intensity
• Problems with initialization

• Global Model
• 100KM resolution
• Good for synoptic scale flows
• Bad for hurricane intensity

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GFDL Aug . 12th 00Z Initialization
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GFDL Aug 13th 06Z Initialization
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GFDL Aug 13th 18Z Initialization
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AVHRR imagery SST Aug 12th
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GFDL Aug 13th 00Z Initialization
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GFDL Aug 13th 00Z 18hr. forecast
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AVN Aug 13th 6 hour forecast
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GFDL Aug 13th 00Z 18hr forecast
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GFDL Aug 13th 18Z initialization
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AVN Aug 13th 00Z 18 hour forecast
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Results / Conclusion

• EFC and PV during trough interaction can either
  strengthen or weaken a TC
• Excess vertical shear caused by either PV of EFC
  is negative factor for intensification. (Balance
  is important)
• Rapid intensification of TCs is believed to need
  trough interaction, in part to occur.
• Better data analysis, more offshore vertical
  data, and incorporation of data/equations into
  models necessary for accurate forecasting of
  trough interactions.
• Lots theories at work here, and more work needs
  to be done to confirm these ideas.

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ANY

• QUESTIONS?????????????????????????????????????????
  ???
• References are in typed paper