Tuesday, September 6, 2011

Tropical Patterns

Katia has reached major hurricane status in the Atlantic. After Irene lashed the Carolinas and skirted the Northeast, Katia has a lot of east-coasters holding their breath. As Katia formed, I had mentioned that the storm track appeared to take it out to sea and avoid being the second storm to hit the east coast in a month. So far, so good. Here are computer models for Katia's track.

All models have the storm re-curving out to sea. However, a common issue with tropical forecast is that a forecaster may wind up "riding" the models and forecasting what the computers spit out. When it comes to tropical forecasting, patterns almost work better than guidance.

Gut feelings often can be the best forecasting tool, assuming you have knowledge of the situation. Now, being from the Pacific Northwest, I obviously have little knowledge of topical histories. But having picked up a few hints along my studies have helped me to generate some opinions about the 2011 tropical season. My gut instinct was that Katia would curve out to sea. Here is why I stated that.

Take a look at Katia's actual track below.
Let's take a look at where Katia formed. Katia got tropical depression status at roughly 26 degrees West latitude and a day later was a tropical storm at roughly 33 degrees West latitude. So Katia formed rather quickly off the west coast of Africa. Through historical observations made, it has been determined that 90% of all tropical cyclones that develop EAST of 35 degrees West latitude will RE-CURVE off to sea. That is the exact situation we have with Katia. This was my first clue.

My second clue came through a process called teleconnectoins. Meteorologists use teleconnections in order to "anticipate" what may come down the road for a specific location but is used in the most general sense. The basics of this is this: what is occurring in the western Pacific (off coast of China/Japan) will occur on the U.S. east coast roughly 6-10 days later. Nothing is specific, it just assumes general trough/ridge patterns. Teleconnections can help forecast the track of a storm brewing in the Atlantic. When Katia formed, I took a look at what was occurring in the western Pacific. A trough was located just off the coast of Japan. So I inferred that this trough would generally move eastward and ultimately pull Katia out to sea when she wanders towards the U.S. coast!

I've been told it's better to go down on your own forecast than someone else's. So I decided to own my gut instinct and say what I thought; Katia will miss the U.S. and re-curve out to sea. I'm more than happy to live and die by my own forecast. That was a valuable advice given to me by one of my teachers whom I greatly respect.

Looking ahead, we have a new tropical disturbance developing in the east Pacific. Invest-95 has a high probability of becoming a tropical cyclone. Let's compare the track of Katia to that of Invest-95. 

Invest-95 has formed a little south of Katia's track, and is forecasted to track a bit north of Irene's path. Lots of time however for Invest-95 to change, so I'm not making a call on this yet.

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