MOS Watching in Memphis

Yesterday, I picked three cities in the northern and central Plains to follow for lows Thursday morning, highs Thursday afternoon, and lows Friday morning. I want to get a handle on how MOS and raw guidance handle the arctic air mass. So far, model guidance has not busted as bad as I thought it would. Granted, today's high in Kansas City was definitely lower than any of the guidance suggested. Areas further south and east across Missouri and northern Arkansas were consistently 3-5 degrees cooler today than what MOS products were forecasting yesterday.

The further south you go, MOS products will likely have similar or even worse errors because this arctic air mass is a statistical anomaly. Although this air mass is much colder than normal for cities like Omaha and Des Moines, the MOS products should have plenty of these cold anomalies incorporated into its records. In other words, it's much more common for these cities to have cold outbreaks during the middle of winter. On the other hand, cold outbreaks are less common across the South, and there aren't as many of these anomalies built into the MOS records. As a result, look for MOS products to struggle with this arctic air mass across the Mid South. I'll add Memphis to the end of this list, and we'll see how well the models perform tomorrow.

Omaha, NE
12Z NAM MOS -- 2/13/3
12Z GFS MOS -- 3/14/4
18Z NAM RAW -- 3/14/5
18Z GFS RAW -- 4/14/5
Thursday morning low: 5
Thursday afternoon high: 14

Des Moines, IA
12Z NAM MOS -- 3/11/0
12Z GFS MOS -- 2/10/-1
18Z NAM RAW -- -2/11/8
18Z GFS RAW -- 0/9/-5
Thursday morning low: 3
Thursday afternoon high: 12

Kansas City, MO
12Z NAM MOS -- 13/25/8
12Z GFS MOS -- 13/28/14
18Z NAM RAW -- 16/26/16
18Z GFS RAW -- 17/24/16
Thursday morning low: 15
Thursday afternoon high: 23

Memphis, TN (forecast for Friday afternoon high)
12Z NAM MOS -- 42
12Z GFS MOS -- 36
12Z NAM RAW -- 34
12Z GFS RAW -- 30
I think the raw guidance is on the right track for Memphis, but the MOS products should bust badly on the high. It will be interesting to watch what happens.