Thursday, January 8, 2009

Cloud Charts & Omega Block Answers

A comment was left on my Happy New Year blog entry asking for resources to identify clouds.

Click here for the official National Weather Service/NASA cloud chart. It will open up in a PDF file and you can either save it to your desktop, or print a copy if you have a color printer.

And yesterday's blog sparked a thought that I didn't completely answer in the blog entry itself, and that is how long does an omega block pattern last and what does it take to break it up.

Good question -- and there is no answer.

The length of an omega block pattern depends on the strength of the high and low pressure systems that are interacting.

So let's say you have a block pattern made up of a trough of low pressure in the middle with a ridge of high pressure on each side.

The ridge of high pressure to the east is typically what is "blocking" the flow of weather -- so the Omega Block pattern will potentially last until something gives -- meaning either that eastern ridge of high pressure just breaks down and weakens, OR -- if something in the upper air pattern comes along that is stronger and forces the pattern to shift or move out.

I read several forecast discussions today from Pueblo, Colorado to Little Rock, Arkansas --- and Goodland, Kansas to Minneapolis/St. Paul, Minnesota --- everyone is now talking about the models becoming more consistent with an arctic outbreak next week.

It looks like very cold air is on the way, but the big questions are the timing and exactly how long the air mass will stick around and how much territory will the air mass cover.

Very exciting stuff -- can't wait to see what happens!


  1. It is getting cold! I wish I could keep up with CoCoRaHS, but we are moving to the city. Can I still make reports there?

  2. Chris:
    I thought I'd share a link with you and other weather watchers. There is a vast wealth of info on this site and I have found it to be extremely helpful and informative - especially during hurricane season. It's

  3. Great blog! I appreciate the link to the chart. I have an older version in my office, but I would love to get this one in poster size. Is a high quality poster sized print available anywhere?

    Come check out my weather blog at Have a terrific weekend!

  4. Is it my imagination or has it generally been windier than normal here in the midwest the past year. My location is NW KY.

  5. The link does not work for me.

  6. Thanks for the cloud chart. The most helpful resource I have used.

  7. These charts are fantastic. does anyone know where I can find online sites that are looking for forecasters