How to Read A Skew-T Diagram

[Wx4cast]

The individual white charts that I posted in the LES thread are cold "soundings" in this case forecast sounding from a particular model (in this case the GFS) for both a particular location and specific time.

In simplicity it is a plot of air temperature (the red line) and dew point temperature (the green line) versus height. Height is plotted not in feet but millibars. Along the righ vertical asix going up is the forecast wind speed and direction (in degrees). On the direction shaft you will see lines (called barbs) a full barb is - to 10kts, a 1/2 barb is 5kts and pennants are 50 kts. So for example if you had a pennant followed by two full barbs and a half-barb the wind speed would 75kts (I use knots on my forecast sounding data, some plots use meters/sec)

The far right data blocks show forecast instability parameters, shear and helicity/holicity values as well as layer thickness'. Thickness is basically the distance between two pressure levels. The greater the distance between levels the higher the thicknes, the warmer the air. The less the distance between the layers the "colder" the air. Thickness data can be useful in determining precipitation type (or p-type). Perhaps at some later date I'll post a brief write-up on how you can use thickness info to forecast p-type.

Anyway more on skew-T's can be found here: Skew-T How to and here More about a skew T

The stretched T-sec maps are what is called a time section. Forecast hours are at the bottom and it is read from RIGHT TO LEFT..Thus the initial model time (0 or 00 hr) is the first hour the last hour is 168 or 7 days hence. Analyzed on the T-secs that I posted are relative humidity (contoured/shaded: dark green is > or = to 70%).

Wind direction and speed is plotted along chosen vertical time axis'. Dashed lines (isotherms) are temps in degrees C 0C is blue and the lavender/purple isotherms are the favored snow growth zone temperatures.

For more (brief summary) of snow growth go to: Snow Growth Dotted yellow lines are vertical velocity (upwards) only.

[Andyace]

The individual white charts that I posted in the LES thread are cold "soundings" in this case forecast sounding from a particular model (in this case the GFS) for both a particular location and specific time.

In simplicity it is a plot of air temperature (the red line) and dew point temperature (the green line) versus height. Height is plotted not in feet but millibars. Along the righ vertical asix going up is the forecast wind speed and direction (in degrees). On the direction shaft you will see lines (called barbs) a full barb is - to 10kts, a 1/2 barb is 5kts and pennants are 50 kts. So for example if you had a pennant followed by two full barbs and a half-barb the wind speed would 75kts (I use knots on my forecast sounding data, some plots use meters/sec)

The far right data blocks show forecast instability parameters, shear and helicity/holicity values as well as layer thickness'. Thickness is basically the distance between two pressure levels. The greater the distance between levels the higher the thicknes, the warmer the air. The less the distance between the layers the "colder" the air. Thickness data can be useful in determining precipitation type (or p-type). Perhaps at some later date I'll post a brief write-up on how you can use thickness info to forecast p-type.

Anyway more on skew-T's can be found here: Skew-T How to and here More about a skew T

The stretched T-sec maps are what is called a time section. Forecast hours are at the bottom and it is read from RIGHT TO LEFT..Thus the initial model time (0 or 00 hr) is the first hour the last hour is 168 or 7 days hence. Analyzed on the T-secs that I posted are relative humidity (contoured/shaded: dark green is > or = to 70%).

Wind direction and speed is plotted along chosen vertical time axis'. Dashed lines (isotherms) are temps in degrees C 0C is blue and the lavender/purple isotherms are the favored snow growth zone temperatures.

For more (brief summary) of snow growth go to: Snow Growth Dotted yellow lines are vertical velocity (upwards) only.

Thank you so much for sharing your knowledge.

[ayuud]

Thanks man

[LakeEffectKing]

Excellent Andy!

If I might add, here's a site that is just chuck full of educational info on the SKEW-T:

http://www.theweatherprediction.com/thermo/parameters/

And the mother page has AWE INSPIRING information!!!!!!!!!

One of my favorite resources on the web:

http://www.theweatherprediction.com/

(Don't forget to scroll down!!.....and scroll....and scroll!!!!!!

Get through all the information and you should get an honorary red tag!!!

[Wx4cast]

Excellent Andy!

If I might add, here's a site that is just chuck full of educational info on the SKEW-T:

http://www.theweathe...rmo/parameters/

And the mother page has AWE INSPIRING information!!!!!!!!!

One of my favorite resources on the web:

http://www.theweatherprediction.com/

(Don't forget to scroll down!!.....and scroll....and scroll!!!!!!

Get through all the information and you should get an honorary red tag!!!

Ah yes, Haby's site. Good ones George...

[Andyace]

I love learning this stuff, I wish I could take a class on it. Seeing and listening to a meteorologist go over it would be the easiest way to learn.

[Tornado Girl]

Andy, all I can say is excellent

Here is a clip that explains an "Inverted-V Sounding"

http://www.accuweath...-inverted-v.asp

This is a link to a PDF file that goes into a little more detail on Skew-T/Log-P Diagrams, in case anyone wants to dive in a little deeper.

http://kiwi.atmos.co...ew-T-Manual.pdf

[Wx4cast]

Tornado Girl thank you; you are too kind.

Folks TG is also very knowledgeable on Stuve Diagrams, Tephigrams and Elsasser Diagrams, too

[Wx4cast]

I love learning this stuff, I wish I could take a class on it. Seeing and listening to a meteorologist go over it would be the easiest way to learn.

That might be helpful but to be honest the really best way is to just immerse yourself in it. Read it apply it see what you can do with what you read and learned. Then if you have questions you can ask.

[Tornado Girl]

Tornado Girl thank you; you are too kind.

Folks TG is also very knowledgeable on Stuve Diagrams, Tephigrams and Elsasser Diagrams, too

I'm sure, I don't know as much as you on the subject...But, what can I say I love thermodynamics

[hudsonvalley21]

Thanks to all that posted. Excellant topic and a great way to learn. Maybe the mods can create a new weather fourm and call it weather 101. :thumbsup: