Is There Snow on the Way?

The 06Z NAM shows us getting about 1/4" water equivalent precipitation between 10AM and 10PM on Thursday (07 Jan); with the expected temperatures in the low 20s, we would expect almost 6" snow. One can only hope. We are within the "at least 10% probability" area for >4" snowfall on the HPC Day 3 outlook.

Overnight we got another dusting of lake effect snow; and reportedly west and northwest of here was another nightmare on the roads. I experienced mostly just wet roads coming into downtown from northeast Fort Wayne; of course, the roads were still mostly snow-packed in Arlington Park (though less than 1/2" thick), despite their attempts at scraping them early this morning.

UPDATE 05 Jan at 22:40 EST

The 06 Jan 00Z NAM has weakened the Thursday storm a bit, promising us only about 4" snow; possibly some slightly heavier snow south of us (from Indy down to Louisville) and also west of us (over Illinois). The storm appears to break apart as it leaves Illinois, with the stronger branch heading up the Ohio Valley (joined by a weak impulse out of the Gulf of Mexico) and then spinning up into a strong storm well off the coast of Maine and the Canadian maritime provinces.

UPDATE 06 Jan at 09:55 EST

I checked my original math (actually, I couldn't read my own writing), and yesterday's 06Z NAM predicted about 4" snow; so the computer model really hadn't changed that much. Today's 06Z NAM still shows us getting about 4" snow between 8AM Thursday and 4AM Friday.

I don't see that impulse from the Gulf joining in and breaking up the storm that I saw on the 00Z NAM; but the western half of the cold front does run into more moisture over east Texas, so the heaviest precipitation area migrates there.

The storm finally wraps into a well-defined low off the coast of Maine by 7PM Friday; but the precipitation stays off the coast, even as the low parallels the Canadian Maritimes.

The winds off Lake Michigan are currently forecast to be too northerly for us to get any of the lake effect snow in the aftermath of this system; but it looks like South Bend should get an additional 6" lake effect snow through Saturday afternoon, and Indy might even get a couple additional inches on Friday.

UPDATE 06 Jan at 19:50 EST

The 18Z NAM has Fort Wayne getting about 3.5" snow between 8AM and 9PM Thursday, and then another 1" snow between 5AM and 2PM Friday. The lake effect snow in the wake of this system is not forecast to be as strong as earlier forecasts; there will be lake effect snow in South Bend, but moderate only for a few hours on Saturday (so probably only 2 to 3").

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awc 2010-01-05 09:41