BTW, the latest GFS at 96 hours (one of the models) is suggesting 20 inches for Eastern Iowa.
http://grib2.com/gfs/CONUS_GFS0P5_SFC_ACCUM-SNOW_96HR.gif
http://grib2.com/gfs/CONUS_GFS0P5_SFC_ACCUM-SNOW_96HR.gif
Weather Thread 1/30-2/2: Possible Major Storm
- Thread starter Iastfan112
- Start date
So whats the difference between the NAM and GFS models? Which one is more accurate? because NAM says that I'll be getting 12-16 inches, and GFS is between 5 and 9.
As of a week ago slightly above normal in DSM, a little bit more above normal in Waterloo.
Different data assimilation, NAM is higher resolution mid range model as well as being regionally based, GFS is a global long range model.
exactly one inch above normal for the winter (normal snowfall for this time of year is just under 21 inches). Also as of early this morning when Saturday's climate summary was released, the NWS was reporting a snow depth in DSM at either the airport or weather office in Johnston of 5 inches, of course that depth varies from one part of the metro to another.
In theory, NAM (North American Mesoscale Model) has finer resolution while the GFS (Global Forecast System) is, well, global. Since the GFS is not as fine of resolution it can be run out to longer times, but with finer resolution the NAM should be more accurate in the short term. But, in reality, that is not exactly the case every time.
Since the GFS does not have a fine resolution, it tends to "smear out" precip features, meaning a greater area resolved as seeing precip, but not many local maxima, while the NAM can theoretically pinpoint the precip better, and show more in terms of local maxes. Again, doesn't always mean much.
For whatever reason, it seems like the NAM has been going on the crazy high end for a lot of the snow events this season. Hasn't been wrong every time, but have definitely seen a trend of it being somewhat of an outlier in terms of totals.
So far Des Moines has 21.8". Normal to this point is 20.8"
For the Chicago area, a Blizzard Watch has replaced the Winter Storm Watch and I wouldn't be surprised to see more Blizzard Watch's go up later this afternoon.
Blizzard Watch just issued for greater Chicago area. Tom Skilling is talking about the possibility of a record breaker here in Chicago, which would mean 2 feet of snow. Most QPFs are coming in greater than 1.6, with the NAM showing greater than 2 inches. 14-1 average ratios. This is setting up to be a baby maker.
pink =12-15in
red=15-18in
with des moines kinda on the border, looks like earl's calling for about 15" here. ****
