Issued at 8:39 PM CST, Tuesday, December 22nd, 2009
…All headlines remain in effect, refer to previous updates for that information…
00z NAM concerns me somewhat, not so much the track or timing as that remains largely unchanged from previous runs, but the latest NAM surges the 540 thickness contour well west toward Central Minnesota toward late Thursday Night and Friday as the main surface low forms across Arkansas then lifts almost due north, if not a little northwest of north as it reaches Central Iowa by Friday Morning. The low is expected to deepen to around 989-993 mb by Thursday Night/Friday.
The 850 mb temperatures per latest NAM hover around the zero degree C range from Thursday Afternoon through Friday across all of Northwest Wisconsin back through the Twin Ports and south through Pine County, while surface temps get awfully close to that low 30 degree range across Northwest Wisconsin back through Northeast and Eastcentral Minnesota.
Bottom line is that we could end up seeing more ice or sleet to go along with the snow across portions of our area with this storm.
Forcing looks to be quite intense, however, and the strong forcing in place north of the surface low could create enough dynamic cooling to keep precipitation falling as snow.
The 00z NAM from This Evening continues to crank out very heavy QPF across Northern Minnesota and Northwest Wisconsin…In fact, if precipitation falls mostly as snow here in Duluth/Superior, then we should have no problem reaching 12″, probably even more than that by Saturday based on the QPF being generated by the NAM.
Still thinking all of our area will see at least 6″ of snow from this storm between Thursday and Saturday, with an increasing potential for sleet and some ice accumulations as well…Especially in Northwestern Wisconsin and possibly into Eastern and Northeast Minnesota.
There will likely be an axis of snow totals which will reach 12-20″ somewhere in Northcentral…Eastcentral…Or Northeast Minnesota.
This is a dangerous storm anyway you slice it. Stay tuned for further updates.
Tim
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