April Flowers bring May Snow Showers, May 10, 2008

Working the West desk the biggest issue will be Denver.

Denver is a weird place weather-wise. It can easily be in the 70’s one day and the next snowing. This happens a lot. The reason is the close proximity to the mountains, the high elevation, the way the Rockies are situated across North America and other things.

So when I came onto shift, the forecast had already been changed once to put thunder into the forecast. The biggest issue we could see was the chance for snow mixed with rain. The temperatures above the surface were cold enough to support snow, but the surface temps were going to be near 50 degrees. So the only way snow was going to fall was for the rain to fall from a cumulonimbus cloud and due to dry air near the surface the rain evaporates which cools the temperature enough. As this evaporation is occurring the air is becoming more moist and eventually it can rain, but also now the temperature is cold enough to support a mix of rain and wet snow.

I have seen it snow with temperatures in the 40’s so I know it can.

The conflict I faced was how to play the forecast. There was a chance of rain, snow, hail, and thunder. I really didn’t want to play thunder snow, but I wanted to play snow. So I mentioned a chance for off and on rain/snow showers with CB’s to hint at the possibility of thunderstorms.

Sure enough at the peak time for the precip, thunder hit the airport with hail being reported. However, the bigger issue was the winds. The system causing the rain/snow was growing stronger and so the winds were increasing.

If there were any delays, it was likely due to the winds before the rain/snow.

Coming up on Tuesday, an even colder and bigger storm may bring all snow to Denver, but that will have to wait.

As for San Francisco, the stratus like I thought and forecast did not come in.

Probably the best t.v. job in the country is in San Francisco. The public could care less about the stratus, so all they have to do is say partly cloudy every morning.  Also, the Bay Area is always nice temperature-wise.

Stratus will likely return on Sunday morning and it may stay in through the afternoon. That being said, there will be very warm conditions next week with highs near 80 in San Francisco.

With the warm conditions in San Francisco, expect to see wildfires in Southern California as the strong, dry Santa Ana winds will be going.

One other thing going on that most people I don’t think associate with the weather, but is a concern to aviation are volcanoes. In the last week, two major eruptions of two volcanoes we hardly ever deal with, in fact one that we never deal with, have gone off. Chaiten in southern Chile and Etna in Sicily. Volcanic ash is very dangerous to the engines on airplanes. You won’t necessarily crash, but it can damage the plane.

Also, Chicago is not going to be good on Sunday.

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