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Weather Q & A

Weather Q & A

by Steve Templeton

KMOV.com

Posted on November 18, 2009 at 10:47 PM

Updated Monday, Nov 23 at 6:04 PM

 

So in my last blog I talked about how the 7th graders at Carrollton Middle School are following the blog this week.  And they have a lot of questions, so let's dive in...

 I'll post the question they asked and then answer it below:

Why does the rain to snow ratio increase as air gets colder? (In the previous blog we talked about how much snowfall all this rain would be equivalent to)
Because colder air is typically dry air.  Without as much moisture in the air, the snowflakes have more air pockets and the snow is more of that fluffy snow.  Also, this type of snow is not great for making snowballs because it falls apart easily.  For decent snowballs you want temperatures around 28 to 32. 

Has there been a change in the atmosphere to cause this much rain?
Recently (the past 4 days) our rain can be attributed to a cut-off low pressure system.  Basically, that's a rain system that got cut-off from the flow in the atmosphere that moves weather from West to East.  Since it's been cut-off it doesn't move much until something comes a long to push it out.  That's finally happening Thursday and Friday. 

How do you measure how dry the air is?

Instruments such as a hygrometer or even a Sling Psychrometer measure humidity in the air.   

How often do you use the computer for forecasting precipitation? Are there other resources you use? If so, which is the most reliable?

I use computer projections for forecasting everyday.   A lot of the forecast model information is available on line, like here (http://www.meteo.psu.edu/~gadomski/ewall.html).  It will look confusing to you, but my job is to interpret these and other forecast models and come up with what I think the forecast will be based on the computers and my knowledge and experience.  As for one model being the most reliable, unfortunately it doesn't exist.  Some models work well one week and then do poorly the next.  What I do is look for consistency in the forecast projections.  Also, I know from my experience which computer models tend to produce too much rainfall or move a low pressure in too quickly or clear out the clouds too fast or produce temperatures that are way cooler for no apparent reason.  Some days I see one model showing a high of 65 and another a high of 45.  It's my job to figure out why one is warm, the other is cool and which one will be right.

Thanks for blogging with me Carrollton!  I love that you guys are totally into weather.  If something comes up during your weather unit and you need my help explaining it, don't hesitate to email me.

Steve Templeton

 

 

 

 

 

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