Tuesday, November 10, 2009

Skew-Ts

As promised... here's a brief intro on how to read soundings or "Skew-Ts".
Every Skew-T diagram has 2 "curves" the one on the left (green) is always the dew point temperature. The one on the right is always the actual temperature (red) with respect to height.
The circles with lines coming out of them on the right side of the diagram show us what direction the wind is coming from at each height and how strong the winds are at that height. The longer the line and closer to purple on the rainbow spectrum... the stronger the wind.
We can use the dew point and temperature "curves" to determine cloud cover and rain if we use forecast soundings... so "Skew-Ts" of what some models think the atmosphere will look like in the future. On a day like today, the temperature and dew point "curves" are very far apart at the surface (or the bottom of the plot) and the two stay decently apart from each other as you go up in height. That means that we have a very dry and stable atmosphere so we should expect sunshine with no clouds.
But we take a look at a sounding for Friday (this is the forecast sounding for 1pm on Friday) when our next BIG system is expected to bring rain showers and the profile looks incredibly different. The dew point and temperatures "curves" coincide which means that they are the same temperature. (I circled them in yellow) When that happens, it's indicating that there's 100% humidity at that level, which means clouds and rain showers are likely to occur at that time. And Bufkit (which is the program I use to get these forecast soundings) lets you know on the left side that it's going to rain as indicated by the 2 green dots with the letter "R". One dot means a little rain, 2 dots is moderate rain, three dots is heavier rain, and four dots is the heaviest rain.

That's pretty much what you need to know when it comes to soundings... of course we can go way more in depth with these but that's more along the lines of college meteorology courses. At Iowa State, we spent two plus weeks just on Skew-T plots, that's how much information we can get from these diagrams. Pretty neat! If you want to know more, here's a decent site to check out.

Enjoy the dew point and temperature curves being so far apart today!
~KDLT Meteorologist Jesse Ritka

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