A quick peek at the new 12Z run of the NAM shows a nicely developed surface low in the Gulf of Mexico Thursday evening south of Gulf Shores, with a large precipitation mass over Alabama. This confirms our forecast trend for Thursday.
Of course, the NAM shows the lower atmosphere warm enough for all rain, which might be correct for the I-20 corridor (see the early morning discussion). BUT, the NAM will have no clue about the cold air near the surface. The sounding from Birmingham this morning shows the cold air only about 1,800 feet thick, and there is no way the NAM or the the GFS has the resolution to handle that. Birmingham has now dropped into the 30s; just recently the MOS guidance from both models thought we would be in the 50s today. Forget those MOS numbers in shallow cold air... they stink.
The GFS is out to 54 hours at this moment, and it will probably look like the NAM... finally catching on to the idea of a storm in the Gulf later in the week. And, like the NAM, it won't understand the shallow cold air near the surface.
Bottom line is that at first glance on the 12Z guidance I don't see anything to change the thinking from what is posted below... if this were January, we could be in big trouble. Still, there is a real chance of a wintry mix mainly for areas north of U.S. 278 Thursday, and maybe a small window for some bridge icing as far south as Birmingham early Thursday morning. But, mostly a cold rain around here.
By the way, J.B. Elliott reports seeing the cold air so far this season in the Yukon; he found a -51 this morning (he will have more on these observations here later)... makes you wonder about the latter half of the month.
Headed out for a number of chores... will have a full post by 3:30...
Of course, the NAM shows the lower atmosphere warm enough for all rain, which might be correct for the I-20 corridor (see the early morning discussion). BUT, the NAM will have no clue about the cold air near the surface. The sounding from Birmingham this morning shows the cold air only about 1,800 feet thick, and there is no way the NAM or the the GFS has the resolution to handle that. Birmingham has now dropped into the 30s; just recently the MOS guidance from both models thought we would be in the 50s today. Forget those MOS numbers in shallow cold air... they stink.
The GFS is out to 54 hours at this moment, and it will probably look like the NAM... finally catching on to the idea of a storm in the Gulf later in the week. And, like the NAM, it won't understand the shallow cold air near the surface.
Bottom line is that at first glance on the 12Z guidance I don't see anything to change the thinking from what is posted below... if this were January, we could be in big trouble. Still, there is a real chance of a wintry mix mainly for areas north of U.S. 278 Thursday, and maybe a small window for some bridge icing as far south as Birmingham early Thursday morning. But, mostly a cold rain around here.
By the way, J.B. Elliott reports seeing the cold air so far this season in the Yukon; he found a -51 this morning (he will have more on these observations here later)... makes you wonder about the latter half of the month.
Headed out for a number of chores... will have a full post by 3:30...
on December 5, 2005, 10:08 am
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