How Much Snow Will Fall?

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The winter storm is now crossing into northwest Utah on its way southeast and gathering strength. It will move into northern New Mexico tomorrow morning and then turn east. 
Circle is current position of the low pressure system.


Here is a computerized snow prediction forecast from the southern half of the Plains east along Interstate 40 valid through Thursday afternoon. 

If you are traveling, it shows poor driving conditions on I-35 between Dallas and Emporia, KS and just about all of I-40 from Amarillo through Nashville. Keep in mind that 6 inches or more of snow in southern Oklahoma east through Arkansas and Tennessee is much more of a problem than farther north because of the relative lack of snow clearing equipment.

When viewing these maps, you cannot take them too literally. The small features like the 10" amounts are small enough they might not be placed just right*.  I think the 10" shown in Wichita is at the high end of what we will receive, I think the actual amount will be 5 to 10". Amounts may be a little too high elsewhere.

[If you are not interested in meteorological explanation, stop here.]

Why might the computer forecast be a little high? The reason is that the weather balloons and satellite sensors this evening shows that the Gulf of Mexico moisture has not crossed the coast back into Texas.
Satellite sensed atmospheric moisture. The yellow amounts
(which are in millimeters) need to get into the storm for
ten inch or more amounts to occur. 
Right now, the atmosphere is just too dry. If it were forecast to stay that way, the forecast would be straightforward. But, here is the complicating factor (and why meteorologists tear out their hair): A low-level jet stream that does not currently exist is forecast to form tomorrow morning and is expected to intensity.
Red arrow represents 3,000 ft. jet stream with 55 mph winds.
This forecast is valid noon tomorrow. 
The low level jet might be able to bring up enough moisture for the storm to squeeze out ten inch amounts in a few areas, if the jet is as strong as predicted (55 mph X 12 hours = 660 miles).

I'll update the forecast tomorrow morning when we have a better idea as to whether that moisture will make it in time to increase the snowfall amounts. Meantime, get ready for another blast of snow.

Farther east, the storm is expected to weaken after it passes western Arkansas. But, even a few inches of snow can cause major driving problems in Tennessee.


* Last week's blizzard was so large, our techniques worked quite well. Small features (i.e., smaller than 50 miles on all sizes) aren't forecast as consistently.

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