Sunday, January 11, 2009

Sunday Weather Questions & Answers

Today starts the beginning of the American Meteorological Society convention in Phoenix. 4 days of weather fun that I am missing out on but I am sure Nolan will catch me up on all the happenings.

I am loving all the comments over the past few days. Everything from Meteor Wayne talking about the meteor sightings across the Great White North, all the way to the several questions you have asked me.

So let's tackle a few...

CA-TY-3 from near Douglas City, California -- for those who have never heard of this location, it is located in northwest California, just below Oregon.

In the southern extent of the Cascades, it sounds like an amazing place to live. Click here to learn more about Trinity County.

Much of California is currently experiencing some type of drought conditions, with the worst in the northern and central portion of the state.

If you do not have the US Drought Monitor already bookmarked, here is a link for you. It is a great web site. Click here.

The question of is La Nina causing this dry spell came up, and where can one go to find out if rain is on the way.

You all know there is no such thing an an accurate long-term forecast. We can try and predict trends based off current happenings on a global level, but even trends may need updating every 10 days or so.

The Climate Prediction Center is a great web site to bookmark if you want to monitor these trends.

Click here and you will see that in the short-term, the west looks like it will remain dry. But looking in the 1 to 3 month window, there are equal chances for precipitation --- this means equal chances for below, above, or simply normal precipitation.

Pretty vague, I know -- but that is just about all a forecaster can do when there is no strong data to sway the pendulum one way or another.

La Nina conditions are currently developing in the equatorial Pacific. The Climate Prediction Center issues an update every Monday of the year on the current status of El Nino or La Nina conditions.

These updates are somewhat technical but full of great color charts and graphs. Click here and you can check these updates out for yourself.

The weather pattern we have been seeing over the past few weeks, where there is a large ridge of high pressure over the west and a trough of low pressure in the east is pretty typical during a La Nina weather pattern.

Essentially, storms slam into the Pacific Northwest, cruise along the Canadian border and dive southeast into the Ohio River valley -- following the upper level wind pattern, or jet stream.

A picture of common weather expected during the January to March time frame for both El Nino and La Nina is depicted below.

Now this La Nina is just setting up, the future weather impacts on the lower 48 and even the globe will depend on how long it lasts and how strong it gets.

So does the future look good for rain in northern California? Just a gut feeling, I would say it looks not so good, but I am basing that off the little bit of climatology I know for your part of the country.

This is the rainy season and you aren't getting it --- so if nothing changes in the near future, it may be a dry year for you -- but again, that is just a thought -- I have no hard evidence to yes or no on the rain.

BettyAnne wrote from Washington state asking for more western information.

As many of you know from watching the news, Washington and Oregon have been hit with a series of storms for several weeks now.

Not to mention, unusually cold air filtered into the region, bringing record to snow to places like Seattle, Spokane and Portland.

There have been widespread power outages, avalanches, and road closures.

Here in Colorado, once the cold weather settles in after Labor Day, the mountains go without rain for months. It's all snow.

In Washington, that isn't always the case. For the most part this winter, much of the mountain precipitation has been snow, with snow levels often between 500 and 2,000 feet.

This most recent storm had origins near Hawaii, and it brought a lot of warm, Pacific air with it.

Snow levels rose to 8,000 feet in some cases -- and once a warm rain fell on all that snow, combined with all the saturated locations at lower levels from the stormy past few months, a huge flood event began.

And Sandy99 -- I love your comment.

1. Author of "Hot Lies" claies that most official US weather recording stations do not meet critieria and many are locate over pavement, heating units and BBQ grills. He postulates that this accounts for poor measurement of US temps and he implied this is why our temps are rising. Is this true?

Absolutely NOT! Official weather stations are almost always at US Airports. Great care is taken as to where the station is placed, what surrounds it, etc.

A statement like that to me is a "hot lie" and was written without much research or care about US weather station and where they are located.

First order weather stations, your major ones, such as Denver, Dallas, Atlanta, Chicago, Minneapolis, etc. -- these weather stations are all on the property of the international airport.

Why? Well most of them are funded by the Federal Aviation Administration.

In the event a weather station does need to be in a less than ideal place, such as on a rooftop --- which is and would be rare -- additional equipment is installed to ensure an accurate reading is taking place and a lot of quality control goes into making sure the station takes accurate data.

The National Climate Data Center has a great web site where you can interactively search for the weather stations near you. Click here.

Finally, when weather systems push across the United States, where do they go?

Well, they follow the jet stream around the entire planet. Much of the weather that impacts the USA moves out over the Atlantic and slams into Europe.

Now characteristics of the weather systems may change because there is a lot of space between here and there and a lot of ground (or shall I say ocean) to cover.

Maybe this will be helpful --- maybe not. If your eyes cross a bit once you look at these maps, don't feel bad. Mine do too.

Try and locate the United States and then Europe in the picture below. (it is hard, the lines aren't heavy).

The US is kind of at the bottom center, just above the key.

The warmer colors are warmer air and the cooler colors the cool air. Where the gradient is tight, or temperatures change rapidly over a short distance is essentially where the jet stream is currently located.

So storms follow that track around the globe and bring unsettled weather to places it crosses.

So you can see the big trough of high pressure (warm air) in the west and the large dip of cool air, showing the trough of low pressure, over the eastern part of the US.

If you are feeling brave and want to look at computer models on the global scale, following this link.Click here.

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