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26 Sep 2020

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WRF 4km - Difference in precipitation forecast between 00Z23SEP2021&12Z23SEP2021 2 years 6 months ago #890

ameerrh Topic Author Offline Junior Member Posts: 32 Thank you received: 0	Hi, Why there is a big difference in precipitation forecast between the two references 00Z23SEP2021 & 12Z23SEP2021 in the WRF Israel 4km? Ref:12Z23SEP2021 seems to underestimate the precipitation significantly. This is very clear when comparing the two references 00Z and 12Z as shown in the screenshots below. I think there is an issue. Screenshots for the Ref: 00Z23SEP2021 Attachments:
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WRF 4km - Difference in precipitation forecast between 00Z23SEP2021&12Z23SEP2021 2 years 6 months ago #891

ameerrh Topic Author Offline Junior Member Posts: 32 Thank you received: 0	Screenshots for the Ref: 12Z23SEP2021 for the same forecast times as in the screenshots above. Attachments:
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WRF 4km - Difference in precipitation forecast between 00Z23SEP2021&12Z23SEP2021 2 years 6 months ago #892

davidgal Offline Administrator Posts: 299 Karma: 1 Thank you received: 73	Hi, There is an explanation. The 12z run is using a different configuration to try to improve precipitation forecasts. The 00Z run is without any changes. For the next few rainy days I will be trying different cumulus, micro-physics and radiation schemes on the model. I already see that the cumulus scheme is not so great. David
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WRF 4km - Difference in precipitation forecast between 00Z23SEP2021&12Z23SEP2021 2 years 6 months ago #893

ameerrh Topic Author Offline Junior Member Posts: 32 Thank you received: 0	Hi, I think there was an issue in the precipitation forecast and also in the simulated radar reflectivity (dBZ) forecast for the last days in the 12z run with this different configuration. Was this issue caused by the settings of this new configuration or is there another reason? Has this different configuration been used in the last few days without the cumulus scheme? Thanks
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WRF 4km - Difference in precipitation forecast between 00Z23SEP2021&12Z23SEP2021 2 years 6 months ago #894

davidgal
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Posts: 299
Karma: 1
Thank you received: 73

The 12Z forecast has been running with a different configuration for the last few weeks. When there is no precipitation in the atmosphere the difference will not be noticed.
Now that there was some precipitation in the last two days the differences are noticeable. From the last 12Z forecast the cumulus scheme is the same as the 00Z forecast but the radiation (both short and longwave) and the microphysics schemes are different.
David

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WRF 4km - Difference in precipitation forecast between 00Z23SEP2021&12Z23SEP2021 2 years 6 months ago #895

ameerrh Topic Author Offline Junior Member Posts: 32 Thank you received: 0	Hi, I also noticed that the forecast of simulated radar reflectivity (dBZ) is different in the 12z run. Is this due to the use of different radiation and the microphysics schemes? Can this change in the simulated radar reflectivity forecasting (as shown in screenshots below) be considered an issue or is it evidence of improved forecasting? Attachments:
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WRF 4km - Difference in precipitation forecast between 00Z23SEP2021&12Z23SEP2021

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