Horrible Moisture

Saturday's 12Z/18Z runs trapped a boatload of low level moisture over MI with high pressure overhead, leading to complete OVC and temperatures only in the lower-60's for southern MI during the heart of the day. Something catastrophic would have to take place for that to happen in mid-July around here, and by 00Z Sunday it looked MUCH better but those two runs were horrid.

Thanks - sorry about forgetting the timestamp! I was referring to today the 10th, and clearly NAMY is much more likely to verify than the NAM...

Rob and others --

I removed my examples from the string because I found out that that particular NAMY run (that looked much better than the NAM with its 2-m temps) was started from different initial conditions from usual, because the 18 UTC NDAS (the NAM Data Assimilation System) failed and the NAMY for 12 UTC 9 July was started from interpolated [b]GFS[/b] initial conditions, so it wasn't a clean comparison. Not only that, but the NAM overamplified a trough to create a 570-dm 500-hPa low over southwest lower MI while the NAMY had something that just progressed along; probably the right answer on the 2-m temps was the result of the initial system being weaker in the NAMY as the initial condition was interpolated from a coarser model.

That being said, the cool bias seems to be seen quite a bit in the NAM. One of the culprits that has been discussed is too little vertical mixing. Rest assured the problem *is* being worked on, and that there are some possible improvements in the works. Timing on getting anything implemented, however, is unknown at this time.

Bill