(12-24-10) White Christmas Almost Here!

Models continue to come into agreement that main surface low will move into the Gulf of Mexico. However, a nice dip in the jet stream in the mid layers of the atmosphere will cause enough spin in the atmosphere to produce upward motion needed to produce snow. The timeline still looks like the main brunt of the snow will beging late this evening. At 8am this morning, snow is already moving into southern Illinois, but I think that since the air is not saturated yet, it will take a while for this to reach the ground. It still looks like it will be late afternoon into the evening hours before we start to see much in the way of snow here in Dubois County.

To that effect, the National Weather Service in Louisville has placed us under a Winter Weather Advisory beginning at 6pm tonight and lasting through Noon on Christmas. While this won't be a major blizzard by any means, a few inches are expected to fall. Bufkit sounds place snow ratios in the 13:1 to 17:1 range with a QPF (quantitative precipitation forcast - liquid precip in other words) at about a quarter of an inch. That would be just over 3 inches of snow at the 13:1 ratio and about 4 inches at the 17:1 ratio. All in all, I think a solid 2-4 inches is a pretty good estimate of what to expect. Some areas of Southern Indiana may get less and I hope we're one of them!

As you can see in the graphic below, the HPC has placed us at the edge of a moderate risk (40%) for having snowfall at least 4 inches. There is some pretty strong agreement among all models and forecasters now that we'll see a decent snowfall.






Again, travel conditions tonight could get very rough, so pay close attention to the road, slow down to a reasonable speed and don't go out unless you have to once the snow begins. Have a very Merry Christmas and I'll return to blogging in a couple of days.