Tuesday, September 21, 2010

Tropical Moisture - A Weather Model's Worst Enemy

September 21, 2010
5:43 P.M.
Hey guys, I have some breaking news! Ok, just kidding, it's not really breaking news. The weather models are acting up (I wish they weren't, THAT would be breaking news!). Tropical systems are being entrained in the westerly flow. This doesn't necessarily mean we will have a big storm (although since there are high PW values, we could get a good dose of rain). What it DOES mean is that the computer models are all over the place. They typically have a hard time deciphering what will exactly occur in situations like this, and this specific situation is no different. Take a look at the forecast model yesterday showing a large low pressure center off of our coast early Monday...

And now look at what today's run gave for the same time; a much weaker storm that actually doesn't even end up hitting the coast at all (goes north into the Alaskan panhandle).
As you can see, these are vastly different scenarios, and if you looked at the other frames following them, you'd see even more drastic differences in the way they unfold. One could give a solid inch of rain to the lowlands in 24 hours with much more in the mountains, as well as generating swells in the region of 15-20 feet. On the other hand, the latter, more recent solution doesn't even impact us. Hopefully, as forecasting technology gets better, occurances like these will be more common. Now you can see why the National Weather Service can have a tough time forecasting storms!

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