points exceeded v_cfl over an isolated mountain/volcano (~5km high) at 1km resolution

[xiaominghu]

I try to run WRF 4.6.1 over a mountainous region, my 3 km resolution run works fine.
But when I nest a 1km resolution domain, it complains about "points exceeded v_cfl = 2 in domain d03", see detailed message in https://caps.ou.edu/micronet/Region...NNEDMF.2025040200_cfloverMisti/rsl.error.0316
The location (Max W: 142 201 5 W: -18.55 w-cfl: 3.06) points to an isolated mountain/volcano about ~5km high (as shown in the attached figure).
I tried different physics, different vertical layers, different time steps, all did not work. If I use too small a time step, e.g., 5s, it crashes because of segmentation fault.
Are there any other ways I can try? Thanks

Here are the wrfinput wrfbdy and namelist.input

https://caps.ou.edu/micronet/Regionalclimate/WRFV4.6.1/WRF1km_PeruHu2023JGRConfigMYNNEDMF.2025040200_cfloverMisti/wrfinput_d01

https://caps.ou.edu/micronet/Regionalclimate/WRFV4.6.1/WRF1km_PeruHu2023JGRConfigMYNNEDMF.2025040200_cfloverMisti/wrfinput_d02

https://caps.ou.edu/micronet/Regionalclimate/WRFV4.6.1/WRF1km_PeruHu2023JGRConfigMYNNEDMF.2025040200_cfloverMisti/wrfinput_d03

https://caps.ou.edu/micronet/Regionalclimate/WRFV4.6.1/WRF1km_PeruHu2023JGRConfigMYNNEDMF.2025040200_cfloverMisti/wrfbdy_d01

https://caps.ou.edu/micronet/Regionalclimate/WRFV4.6.1/WRF1km_PeruHu2023JGRConfigMYNNEDMF.2025040200_cfloverMisti/namelist.input

 

[William.Hatheway]

A couple things I have tried over the Himalayas that might help in the &dynamics section

 epssm                               = 0.9,                         ! time off-centering for vertical sound waves

 etac                                = 0.02  ! znw(k) < etac; eta surfaces are isobaric

Now I'm not 100% certain what these do exactly to the model, I found them buried in the old forums posts, but it did make the cfl violations go away.

 

[xiaominghu]

Excellent! I put epssm = 0.5, 0.5, 0.5, and it worked like a charm! thank you so much!!

 

[William.Hatheway]

Excellent! I put epssm = 0.5, 0.5, 0.5, and it worked like a charm! thank you so much!!

Happy to help