The weather set up for today and tomorrow for Jefferson County is fairly complex. For the initial set up we know that is has been very hot and humid for the last couple of days. This heat and moisture is the fuel for spring thunderstorms. The first graphic we will look at is the national weather map from the NWS.
The first thing that stands out is the yellow hashed area that represents the area of suspected severe thunderstorm activity. What I am looking for here is what is going to initiate the storms to develop. I see a surface low that is projected to move from West to East across the State today into tomorrow. The second thing I see here is the two stationary front lines extending from the low. What is missing from this graphic is the dry-line that extends south from the low along the western flank of the yellow hashed area. From this graphic it appears that the storms will be initiated around or just ahead of this dry-line as the surface low moves across the State. The other thing that catches my attention is the intersection of the fronts and the dry-line. This is what we sometimes hear as a triple point.
Now, I need to try and figure out how quickly this low is projected to move across the State to try and gauge the impact and timing that the storms will have on the County. I turn to the weather models to get a rough idea of timing and severity. Below are the early morning model runs for 2pm and 5pm from the NWS.
Comparing the two graphics, I look for the circular clear area that denotes where the low is and the initiating line which is the dry-line extending from the low. Comparing these it appears that this low is moving very slowly across the State and we will be impacted by this system for quite a while.
Next I want to know how severe these storms are expected to be. For that I have to differ to the experts and I go straight to the Storm Prediction Center webpage and look at thier convective outlook.
This graphic shows the greatest threat of severe weather is along that dry-line we identified earlier. Next I look at the tornadic threat graphic.
Looks like we are in the 2% probability range. Next I look at the damaging wind graphic.
We are in the 15% probability range here. Next it’s to the hail graphic.
Here we are looking at 15% probability, but we are close to the 30% area.
This leads me to expect that this afternoon around 4pm we will start to get impacted by mature thunderstorms with the potential of hail, damaging winds and a very slight chance of a tornado. In addition I am expecting that there will be multiple waves of storms throughout the evening and into tomorrow.
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