Rapid Refresh (RAP) and High-Resolution Rapid Refresh (HRRR) Forum
cold air damming/outbreaks this week in RUC
Posted By: Stan Benjamin
Date: 30-January-04 0143Z
This is a post of general weather interest. We here at FSL monitor the use of the RUC in NWS WFO area forecast discussions (AFDs) (look at http://ruc.fsl.noaa.gov/sfd). With the hazardous weather over the eastern half ot the country, this week has had the heaviest use of the RUC in AFDs that we have yet seen. Maybe the AFDs have just been longer in general this week with the rather dramatic winter weather.
Here is the theme that we've seen mentioned in the AFDs this week -- the RUC has done very well with the cold air damming in the east and cold air outbreak in the midwest and appears to have maintained these features better than the other models. See Julian date 04028 especially. If this is true, it would maybe be attributable to a combination of factors: 1) very low vertical and horizontal diffusion, 2) interaction between the cloud microphysics with more explicit hydrometeor types forecast and radiation, and 3) cycling of snow cover in the hourly RUC assimilation cycle.
To round things out, we also noted some problems with the Washington/Oregon snow/freezing rain event in early January in that the RUC (like other models) washed out the cold wedge prematurely. Maybe there were more subtle mesoscale issues that the RUC could not capture at 20km, such as the gap flow down the Columbia into Portland.
Any comments on RUC behavior, good or bad, would be welcome to help us learn more. You can post or write directly to me. Thanks. If you look at the AFDs yourself through this web site, the html versions have 'RUC' highlighted (helpful) but also have some repeated AFDs (annoying).
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