Notes from the 2/13 CSTAR TC/QPF conference call

Notes from 2/13/13 CSTAR QPF conference call

6 participants

  • Barrett Smith (RAH)
  • Gary Lackmann (NCSU)
  • Jordan Dale (NCSU)
  • David Roth (HPC)
  • Jonathan Blaes (RAH)
  • Josh Palmer (SERFC)

Most of the call covered the following topics:

  • Jordan took a few minutes to review his WRF model simulations of Hurricane Ernesto (2006).  He ran a lagged average, physics, and data source ensemble for a control run. Interestingly, every model run exhibits a westward bias when compared to the official track for Ernesto.
  • A simulation using GFS initialization from 12Z, 30 August was selected as the control run, as it exhibited the best representation of QPF, with the least track error.
  • Weak cold air damming was observed, and verified with a technique from Bailey et al. (2007), as Hurricane Ernesto approached the Carolina. It is hypothesized that model simulations may not be accurately resolving the cold air damming, which would allow the simulated hurricane to move further inland instead of being steered further east.
  • The development of cold air damming may have been linked to a Predecessor Rain Event that occurred over NC/VA prior to landfall, leading to a rain-cooled and stable airmass ahead of the approaching TC.  Jordan has started work on removing Hurricane Ernesto’s vortex from the control run.
  • Early results suggest that the Predecessor Rain Event still occurred, even when the hurricane circulation was removed (4km grid-spacing run). QPF was similar in both the control run and experimental (no-TC) run.  Further examination of the simulations is ongoing.
  • An experimental WRF run without terrain is being considered as a way to remove the cold air damming airmass.
  • The next call is tentatively scheduled for Wednesday, March 6th.
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