How to improve convection triggering?

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meteoadriatic
Posts: 1515
Joined: Wed Aug 19, 2009 10:05 am

Re: How to improve convection triggering?

Post by meteoadriatic » Sun Nov 19, 2017 3:50 pm

I tried to find some useful information about RH based KF trigger (3) but there is almost nothing available. However I gave it a shot and it does look good on first glance. MSKF seems drier yes.

But I don't think that convection parametrization is main problem because in certain situations that I mentioned at thread opening, convection permitting runs like 4x4km or finer grids without cu_physics are also dry which leads to conclusion that something other is wrong also. My point here is that we should not rely on convection parametrization to fix what explicit triggering does not see. It is acceptable on coarse grids but for fine grids using cu_physics to "improve" convection is not what we want really even if scheme could work on finer grid like MSKF. I still suspect in PBL schemes but as summer is behind that problem does not have my full attention at the moment. However from March 2018 this will again become problem I suspect.

I never got anything back from wrfhelp after I reported several big convection misses that GFS forecasted at least little bit better than any WRF configuration I tried. They said that they are investigating but never replied again. I guess, they also did not find anything useful.

meteoadriatic
Posts: 1515
Joined: Wed Aug 19, 2009 10:05 am

Re: How to improve convection triggering?

Post by meteoadriatic » Sun Nov 19, 2017 10:33 pm

alfe wrote:
Sun Nov 19, 2017 2:26 pm
@norulz :
are you tracking the "Medicane" case ? If yes it would be interesting if you could share what you have got as a comparison between WRF and observation !
For me, it is too far to the east to track it...
Here is mine on 10km grid:
Image

norulz
Posts: 74
Joined: Thu Mar 12, 2015 1:43 pm

Re: How to improve convection triggering?

Post by norulz » Sun Nov 19, 2017 11:22 pm

I didn't follow the storm in Greece closely last week.

I have, however, been able in the past to forecast a Mesoscale Convective Vortex (MCV) that occurred on 25 Oct 2015 hitting Alexandria, Egypt and 6 hours later Beirut, Lebanon. It also spawning supercells that caused extensive damage in Israel.
WRF showed this monster, some 50 kms wide with sustained winds of 70kts and gusts of 100kts. It showed up on 4km grid and 12 km grid. GFS at the same time showed nothing.
There is a report from a yacht that was in direct course of the vortex, measured 70 kts wind and saw the eye of the vortex passing over them.

Here it is on 12km grid
Image

and here on 4km grid
Image
Image

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