A cold front will move across portions of the eastern half of the nation over the next 24 hours or so. Let’s take a look at potential rainfall accumulations, especially in light of areas of the prolonged drought.
First, the current set-up: The first image shows the position of the cold front. Ahead of this front, shaded in green, are pockets of enhanced precipitable water (PW). PW is a good indicator of the total amount of moisture in the atmosphere. The higher the PW values, the greater the potential is for heavy rainfall.
Areas of showers and storms have formed within the region of higher PW, and ahead of the cold front. As this front pushes east over the next 24 hours, showers and storms will also move east. However, just because there is ample moisture, heavy rain is not assured. In the case of this system, the overall upper atmospheric energy, or “upper support,” is weak, and further weakens with time. Consequently, the overall precipitation pattern likely will remain unorganized or scattered in coverage, especially as it moves into Georgia.
Let’s take a look at a couple of models; the first will a short-term model for the next 15 hours, and the second is a medium-term model which captures the entire event. The short-term model shows accumulated rainfall, with heavier amounts in yellow. Unfortunately for Texas and Oklahoma, rainfall remains east once again. The medium-term models more clearly indicates how amounts taper off further east. Heaviest rainfall, averaging between 0.50 and 1.0 inches, will align from Louisiana northward across Mississippi, and brush western and northern Alabama. If you read the latest BWO newsletter, you might remember this is a typical December rainfall alignment.
Finally, much of the nation is in desperate need of rain. The following image shows that the current rainfall is in-between two cores of drought, and at least with this system, heaviest rainfall will remain outside areas that need it most.