Saturday, February 11, 2012

Building Evidence for Active Severe Weather Season

Here is a randomly selected image of today's 6z GFS Ensemble mean 500mb height anomalies. The run time does not matter. What matters is what is being shown on the image.
There is a ridge positioned in the North Pacific, right under a strong low pressure system. Occasionally, this ridge will try to make a move towards Alaska but is being blocked by the strong low pressure system. These two opposing forces appear to be sticking around for a while. What the strong low pressure system does is throw storm systems down into the US, seen by the blue areas in the US. Another thing to notice is the potential jet stream. Look closely at the eastern US. Can you see a tight area of lines? While this is the 500mb level, not the 300mb level, it can be determined that within that region a stronger than normal jet stream is present. 
Let's skip ahead into March and April.
If this pattern sticks around, here is what we will see: A constant stream of storm systems being thrown at the US. These systems strengthen as they gather energy from the above-normal temp. Gulf of Mexico. The warm, humid sector out ahead of the storm, combined with a strong jet stream, would easily make for a tornado/severe thunderstorm event. 
Luckily, Spring is a time of change the atmosphere goes through. The lucky part is how this change ought to break down one or both pieces of the Pacific Block (not an actual pattern name, the 'Pacific Block' I am referencing is the semi-permanent high pressure and low pressure systems). 
Even so, this semi-permanent low pressure system over the Pacific will likely stay put in the Pacific and continue to throw storm systems towards the US. This continues to increase the potential for some active spring weather.

Any questions may be asked below.
Side note: The personal spring severe weather forecasts have been delayed for a little while. My apologies.



Anonymous said...

so when can we expect the personal forecasts now?

Anonymous said...

does this mean an outbreak is coming soon? I will go tell my family about this potentially major tornado.

Aran said...

So it still looks likely for an active spring in the midwest?

Andrew said...

Anonymous #1: Soon.

Anonymous #2: Not 'soon', but maybe starting in the next few months.

Aran: Yes.

Anonymous said...

Hey Andrew, can you include my town, Bethel, Conn., in your Personal Severe Weather Forecast®? Thank you!

- Reid