Monday, November 28, 2011

How Much We Talking?

Everyone wants to know "How much?". That is not an easy question to answer. The reason being that it will be difficult to accurately measure the amount of snow we could see. A lot of this snow is going to melt as it falls through the sky. A lot of it is going to melt as it hits the ground.

I am still feeling pretty good about my projection as to where there could be snow. If anything, I might need to drop my line a little further south. Perhaps something along the lines of "south and east of a line from Murray, KY to New Madrid, MO to Malden, MO to Jonesboro, AR.

Rain is going to continue to fall. Forecast models are still on to that solution. The problem is the temperature profile of the atmosphere. In other words, if you go outside and look straight up, I am looking at the temperatures at different altitudes. In my previous post I went through and showed you what the models were indicating temperatures would be like at the surface and at 5,000 feet. The short range models, specifically the Rapid Update Cycle, are keeping the temperatures pretty close to what I mentioned before.

Cold air is on the move through Missouri. At 2pm CT, it is 33° F in Rolla, Missouri. Temperatures in southeast Missouri, western Kentucky, northwest Tennessee and northeast Arkansas are hovering in the upper 30's.

The tricky part is determining how much moisture will there be to interact with the strengthening cold air later this evening and tonight. Models are indicating that ss the colder air moves in the moisture will begin to move out.

Temperatures at the surface should be a degree or two above freezing as we go through the late night hours. So anything that falls is going to start to melt as it approaches the surface. That is why I don't think we will see any accumulation on roadways. The ground is just too warm. However, we could see a little snow accumulate on elevated surfaces (deck railings) and on grass.

I've extrapolated the following data from a recent run of the RUC model. I am going to use a snow to liquid ratio of 4:1. That is a low ratio as normally, you will see snow to liquid ratios of 10:1. Although, we can see snow ratios as high as 30:1 and as low as 1:1.

CITY | Rainfall amount interacting with below freezing air aloft | Snow
Blytheville, AR | 0.2" | 0.8"
Dyersburg, TN | 0.18" | 0.7"
Jackson, TN | 0.06" | .25"
Jonesboro, AR | .29" | 1.1"
Murray, KY | 0.02" | 0.1"
Walnut Ridge, AR | 0.17" | 0.7"

Keep in mind that the above numbers are if we were able to squeeze out every little bit of moisture and make it in to snow. I just don't think that's going to be the case tonight.

My "Freak Out Meter" is still pretty low with this system. I'm still giving it a 1 out of 10.

No comments: