Rapid Refresh (RAP) and High-Resolution Rapid Refresh (HRRR) Forum
WHICH FORECAST IS USED ON THE SOUNDINGS PAGE
Posted By: Bill Moninger In Response To: Too many forecasts in soundings (Scott Dennstaedt)
Date: 20-September-07 1536Z
In Response To: Too many forecasts in soundings (Scott Dennstaedt)
for the model soundings display at http://rucsoundings.noaa.gov/, the algorithm used is to find the sounding at each requested valid time with the shortest forecast projection. That is, an analysis will be used in preference to a 1h forecast, a 1h forecast is preferred over a 2h forecast, etc.
In the disk directory from which the soundings display gets its data, for the Op20 cycle, 0,1,3,6,9 h forecasts are saved from each hour's model run, and 12 h forecasts are also saved from those runs that occur on a multiple of 3 hours (00, 03 UTC, etc.).
So, if was about 1145 UTC when you asked for the "latest" 12h of forecast soundings (as apparently it was), you'd get the analysis from the 11 UTC run (valid at 11 UTC), the 1,2, and 3h forecasts from that same run (valid at 12, 13, and 14 UTC), the 6h forecast from the run at 9 UTC (valid at 15 UTC), the 6h forecast from the 10 UTC run (valid at 16 UTC), and the 6h forecast from the 11 UTC run (valid at 17 UTC), and so on.
If you want to *force* the display to show a particular forecast projection at a particular "Start time" (i.e., valid time), you can put the negative of the desired forecast projection in the 'Number of hours' box, e.g. "-6" to get a 6h forecast. Of course, there's no guarantee that the forecast projection you desire will be available for the valid time you specify.
Sorry to go into so much detail, but this question comes up periodically, and I thought it would be good to have a thorough answer in the record.
Messages In This Thread
Rapid Refresh (RAP) and High-Resolution Rapid Refresh (HRRR) Forum is maintained by RR/RAP Forum Administrators with WebBBS 5.12.