okie333 Posted February 2, 2011 Share Posted February 2, 2011 The 06Z NAM and the 00Z and 06Z GFS all initialialized with a laughably low snow depth in the Southern Plains. The runs can safely be thrown out since they would likely be too warm. Maps later (I'm on my iPhone right now). Link to comment Share on other sites More sharing options...
baroclinic_instability Posted February 2, 2011 Share Posted February 2, 2011 I would concur with that. The snow depth map does not look nearly high enough in some of the southern plains states and into the Ozarks. Link to comment Share on other sites More sharing options...
okie333 Posted February 2, 2011 Author Share Posted February 2, 2011 I would concur with that. The snow depth map does not look nearly high enough in some of the southern plains states and into the Ozarks. That map's from yesterday morning at midnight. Try the maps on twisterdata for those model runs. Link to comment Share on other sites More sharing options...
okie333 Posted February 2, 2011 Author Share Posted February 2, 2011 12Z NAM has the same issue. Link to comment Share on other sites More sharing options...
okie333 Posted February 2, 2011 Author Share Posted February 2, 2011 12Z GFS has it too. I believe all model runs today will need to be thrown out (unless you can prove that the ensembles and foreign models aren't suffering from this). Link to comment Share on other sites More sharing options...
Zombie-Snowpocalypse Posted February 2, 2011 Share Posted February 2, 2011 I would concur with that. The snow depth map does not look nearly high enough in some of the southern plains states and into the Ozarks. Nice map, what site did you grab it from? Link to comment Share on other sites More sharing options...
WxUSAF Posted February 2, 2011 Share Posted February 2, 2011 12Z GFS has it too. I believe all model runs today will need to be thrown out (unless you can prove that the ensembles and foreign models aren't suffering from this). This is really not that big a deal. I'd be suspicious of the surface temps the models are spitting out in that area, but that's it. This does not invalidate any of the runs. Link to comment Share on other sites More sharing options...
okie333 Posted February 2, 2011 Author Share Posted February 2, 2011 This is really not that big a deal. I'd be suspicious of the surface temps the models are spitting out in that area, but that's it. This does not invalidate any of the runs. I would also be suspicious of p-type, QPF, pressure, wind, snowmelt, soil moisture... basically anything with "Surface", "2m", or "10m" in its descriptor or any quantity derived from any of these quantities. Over time the effects expand to other regions, and the non-surface quantities start to be affected as well. Link to comment Share on other sites More sharing options...
WxUSAF Posted February 2, 2011 Share Posted February 2, 2011 I would also be suspicious of p-type, QPF, pressure, wind, snowmelt, soil moisture... basically anything with "Surface", "2m", or "10m" in its descriptor or any quantity derived from any of these quantities. Over time the effects expand to other regions, and the non-surface quantities start to be affected as well. Minor effects for your immediate area. This would not noticeably effect anywhere else. I'm sure there are far more errors that are also insignificant in the grand scheme. From HPC: http://www.hpc.ncep....ons/pmdhmd.html 12Z/02 NAM AND GFS EVALUATIONSANY INITIALIZATION ERRORS WITH THE NAM AND GFS DO NOT APPEAR TO SIGNIFICANTLY IMPACT THEIR SOLUTIONS. Link to comment Share on other sites More sharing options...
Ian Posted February 2, 2011 Share Posted February 2, 2011 So basically the 8" on the 6Z DGEX may still happen... but with the sole exception that there's around 8-12" still on the ground at that time? huh? Link to comment Share on other sites More sharing options...
dtk Posted February 2, 2011 Share Posted February 2, 2011 I don't understand your point about the DGEX (or why you would even use it to make your case). Here is the 12z NAM initial snow depth for reference/those interested: Link to comment Share on other sites More sharing options...
DaculaWeather Posted February 2, 2011 Share Posted February 2, 2011 It comes from here http://www.nohrsc.nws.gov/ The site is VERY slooooooow right now. Link to comment Share on other sites More sharing options...
dtk Posted February 2, 2011 Share Posted February 2, 2011 Even still, a snow depth error (actually, more so snow versus no snow) would have an impact on near surface temperatures (though these fields need to be taken with a grain of salt to begin with). The notion that it will immediately impact everything is way overstated. Link to comment Share on other sites More sharing options...
dtk Posted February 2, 2011 Share Posted February 2, 2011 I wasn't trying to make a point.I was just showing a model run. Fine, but you showed something that is completely irrelevant to the topic you started (this thread). The snow plot you showed is the snow accumulation for the DGEX run (84-192 hours), and has absolutely nothing to do with the snow depth (analysis/initial conditions) for the NAM (what you showed is not snow depth, but snow accumulation). If you look at the actual plots, you'll see the the 6z DGEX has another storm (mostly overrunning type precip) running up the plains in the 5-6.5 day forecast. Link to comment Share on other sites More sharing options...
okie333 Posted February 3, 2011 Author Share Posted February 3, 2011 00Z NAM has error still. 00Z GFS fixes it minus a narrow strip near the OK/MO border (and maybe some places farther west, and possibly parts of the OV). 06Z NAM should have it fixed too. Link to comment Share on other sites More sharing options...
dtk Posted February 3, 2011 Share Posted February 3, 2011 00Z NAM has error still. 00Z GFS fixes it minus a narrow strip near the OK/MO border (and maybe some places farther west, and possibly parts of the OV). 06Z NAM should have it fixed too. How about showing some examples and giving evidence instead of spewing this out as if it is some sort of "truth". Link to comment Share on other sites More sharing options...
k*** Posted February 3, 2011 Share Posted February 3, 2011 lol Link to comment Share on other sites More sharing options...
okie333 Posted February 3, 2011 Author Share Posted February 3, 2011 How about showing some examples and giving evidence instead of spewing this out as if it is some sort of "truth". First map was the last unaffected model run, followed by two affected model runs, and one that fixed some regions (like mine) and "broke" some other regions (like the southern OV). Link to comment Share on other sites More sharing options...
dtk Posted February 3, 2011 Share Posted February 3, 2011 First map was the last unaffected model run, followed by two affected model runs, and one that fixed some regions (like mine) and "broke" some other regions (like the southern OV). To be honest, I don't really see anything terribly egregious or widespread (to the point you can simply say toss a solution). The surface fields (like snow depth) are not actually analyzed every cycle like the atmospheric variables [they are updated by ingesting a combination of AFWA and IMS analyses, and for the NAM this only occurs at 06z]. This is why you see "corrections" corresponding to that time. In between cycles (say from 12z to 18z), the difference in the initial snow depth is from melting or snow accumulation from the model itself. For more information, a brief description can be found here: http://www.emc.ncep.noaa.gov/jcsda/ggayno/snow.txt As myself and others have pointed out, "errors" in this field will most directly impact surface temperatures but probably not much more in a gross fashion (for example, if an underestimate in snow depth results in a particular point going snow-free too early in the forecast). Link to comment Share on other sites More sharing options...
SpeedyWX Posted February 3, 2011 Share Posted February 3, 2011 OT -- you gotta love that the scale on the map in Post #2 goes to more than 65 feet of snow!!! Cheers! Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.