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The Sounding Tutorial Thread

wx_guy

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Soundings are some of the most important forecasting and real-time analysis tools meteorologists have, and they are a brilliant creation that house a myriad of dense information in a screen. However, for most laypeople, they are obscure and hide their secrets. This thread is designed to teach about soundings, particularly the SharpPy soundings that the SPC, Pivotal Weather, Tropical Tidbits, etc. uses. I HIGHLY recommend downloading SharpPy as a standalone program (can be downloaded on any OS by searching Google! ) because the downloadable program has some more interactivity and features than those on other websites. (Disclaimer: I do still use the others, but having the program is nice to be able to dig deeper!)


Here's an example sounding. Let's dig into the major components! PLEASE feel free to add your own tips and tricks, as Soundings are notoriously complex, nuanced, and confusing for non-meteorologists! (Disclaimer #2: I am NOT a meteorologist, just an enthusiast, so feel free to correct or explain anything I don't explain well. Thanks!)


1705712406500.png


1) Skew-T log p diagram: The main feature in the top-left is called the Skew-T plot. It shows the distribution of temperature and moisture in the atmosphere. The red line is the temp, the green line is the dew point. At the bottom is the surface and you go upward through the atmosphere as you move up the plot. The x-axis is the temperature in C, and the y-axis is the height depicted in millibars of pressure, with 1000 mb being near the surface usually. There are actually a TON more features on the Skew T plot that others that post can elaborate on if they wish, but this plot is extremely useful for various metrics of the atmosphere at any given time. Many of the statistics derived further below can be found in the Skew T plot.

2) Hodograph: The top-right is the hodograph, probably the most well-known feature for tornado and severe weather enthusiasts. It depicts the changes in winds as you move upward through the atmosphere. Curved hodographs or "sickle-shaped" ones, especially in the lower atmosphere (the red part), can be a sign that streamwise vorticity can be turned vertical and lend itself to tornado activity. There are several other quantities shown on the hodograph, such as the storm motion (using Bunkers method) and the Confidi vectors, which will be talked about later.

3) Storm Slinky: This, to the bottom-left of the hodograph, shows the horizontal movement/structure of a parcel of air as it moves vertically into a storm. Kidney-bean shaped storm slinky patterns are common indicators correlated to severe weather and rotating updrafts. The white line shows the storm motion for right-moving supercells. The degrees given shows the vertical slant of the air column with respect to the horizon, so a number near 90 shows a stacked vertical storm whereas lower numbers like 45 or 50 denote very tilted storms. This can be useful to know in figuring out supercell development and overall storm structure.

4) Theta-E Profile: To the right of the Storm Slinky is the Theta-E profile. This shows the "equivalent potential energy" of the atmosphere, starting at the surface and moving upward. Theta-E is measured in Kelvin, degrees K, and roughly combines temperature and moisture into a unified metric of thermal energy of a parcel moving through the layers of the atmosphere. For severe weather, a large Theta-E at the surface and a much lower Theta-E higher up, with a big change as you move vertically, is often looked for. In the example shown, the Theta-E is almost perfectly stable through the atmosphere, so severe weather is much less of a threat.

5) Storm Relative Wind vs Height: To the right of the Theta-E Profile is the Storm Relative Wind vs Height plot. This gives the storm winds (in knots, along the x-axis), at different levels of kilometers (the y-axis) high in the atmosphere. Three bars are shown, a red bar (bottom), a blue bar (middle) and a purple bar (top), indicating the average storm relative winds at the lower levels, mid-levels, and upper-levels, respectively. The dotted white line at 15 kts is often shown as a threshold sufficient for severe weather if the red bar is above it. The purple dotted line separates the threshold between "high precipitation supercells" and "classic supercells" (the purple bar's location is what to look at), and the right edge (at 70 its) is the threshold between "classic supercells" and "low precipitation supercells". Taken together, this and the Theta-E profile can give valuable information into storm mode and what kind of storms may form.


(continued...)
 

wx_guy

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6) Possible Hazard Type: To the right of the Storm Relative Wind vs Height profile is the Possible Hazard Type algorithm. This is a decision tree that deterministically decides threats based on other parameters derived inside the sounding -- it is NOT dynamic or "smart" and does not evaluate based on any nuanced criteria. Instead, if the parameters are met for a certain threat, it is displayed. In this sense, the Possible Hazard Type is relatively crude and is more of a "gut check" that should NOT be relied on. It is easy to look at the sounding and immediately look at the Hazard Type, but deep care should be taken here because it does not factor in the totality of the circumstances. Use it judiciously with other information, not in a vacuum.

7) Thermodynamics: To the bottom left, below the Skew T diagram, is the thermodynamic profile. This contains many stats which are useful. First is CAPE, or the "storm fuel", the convective energy available for a storm to tap into. It is measured at the surface (SFC), the Mixed Layer (ML), the Forecasted CAPE (FCST) <I've read this should only be used in the morning, because it forecasts the afternoon CAPE for that day, and at other times in the day, this is not representative of the actual CAPE.>, and the Most Unstable parcel (MU), which often overestimates the actual CAPE but is sometimes useful. Next, the CINH measures the cap on the atmosphere, if any. The LI, or Lifted Index, is a useful single metric that shows the relative buoyancy of a parcel of air and the instability of the atmosphere as a whole. The LCL, LFC, and EL all give measures of how parcels rise through the air and can correlate roughly to the cloud base and height. PW is precipitable water, and measures how much water can be squeezed out of the air. You can see the Relative Humidity in the lower levels and mid levels as well. DCAPE is a measures of Downdraft energy and is strongly related to the likelihood of microbursts and severe downdraft winds, with numbers of 800+ bad and 1200+ very bad. The Lapse Rates at various levels are shown in the bottom-left and is super important to measure the instability of the air and the ability of the atmosphere to create severe weather. Finally, there's the Composite indices for severe weather - the Supercell parameter, the different Significant Tornado Parameters, and the Significant Hail Parameter. There's a lot of other statistics here as well. Maybe other posts can illuminate them!

8) Kinematics: To the right of the Thermodynamics profile is the Kinematics profile. Here, you can find the Storm Relative Winds, Storm Relative Helicity, and Shear metrics (measured in knots) at various levels, as well as bulk shear. Bunkers Right and Bunkers Left are shown here, too, for right-moving supercells and left-moving supercells. (To get expected storm motion, add 180 degrees to the given degrees - so in this example, Bunkers Right is 255 degrees, so swing that around the circle 180 degrees (in this case you actually have to subtract 180 degrees to remain in the 0-360 range), and you get 75 degrees, or basically East-North East for the expected storm motion. You can check this by looking at the white line in the Storm Slinky, which also shows this.) The second number next to the degrees in the Bunkers Right and Bunkers Left is the expected storm motion, in knots, so the right-moving cells will be expected to move at 8 knots, or about 10 mph. The Confidi upshear and downshear vectors are given, too, and these (from my understanding - please feel free to correct me!) give the expected speed/motion of propagating squall lines (like derechos) and back building setups. Finally, wind barbs give a quick glance at the winds at 1 km and 6 km.

9) The Soundings Analog Retrieval System: This gives two mini-displays, one for Supercells, and one for Significant Hail. Both use ~1000 or so historical soundings and serve up any close or semi-close matches to the current sounding. The Supercells version shows matching supercells of non-tornado variety ("NON"), weaker Ef0-EF1 tornadoes ("WEAK"), and stronger more established tornadoes ("SIG") of EF2 and greater. If you're using the SharpPy program, you can even click on each one to view the actual sounding it comes from (you can't really do this on the website-hosted versions). The Significant Hail version shows soundings that had significant severe hail, along with the size of the hail reported, in inches. At the bottom of each inset, if there is any matching data, it will name how many loose or close matches there were, along with probabilities in that set of (for tornadoes) EF3 and higher tornadoes and (for hail) 2-inch or higher hail. Since the SharpPy program lets you view the actual soundings to compare, this entire feature is much more useful in SharpPy than in website-hosted versions.

10) Significant Tornado Probabilities: This final display in the bottom-right shows the box plots of historical tornadoes versus the current STP value. Look and see where the horizontal colored line intersects the box plots for the most probable tornado strengths. The inset in the top-right also breaks apart the components of the STP calculation and shows probabilities of significant tornado in a supercell based on each component. Each box plot's center is the median STP value for each tornado strength in the historical database used, with the boxes denoting the middle 50 percent of STP values for each strength. The vertical lines (or "whiskers") extending from the boxes are outliers.

==============

There's my summary! Feel free to add to it, explain other statistics, correct anything, etc. I'm hoping this helps make Soundings accessible to more enthusiasts like me! They truly are a wealth of information and invaluable for looking at models and observations.
 

Tanner

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6) Possible Hazard Type: To the right of the Storm Relative Wind vs Height profile is the Possible Hazard Type algorithm. This is a decision tree that deterministically decides threats based on other parameters derived inside the sounding -- it is NOT dynamic or "smart" and does not evaluate based on any nuanced criteria. Instead, if the parameters are met for a certain threat, it is displayed. In this sense, the Possible Hazard Type is relatively crude and is more of a "gut check" that should NOT be relied on. It is easy to look at the sounding and immediately look at the Hazard Type, but deep care should be taken here because it does not factor in the totality of the circumstances. Use it judiciously with other information, not in a vacuum.

7) Thermodynamics: To the bottom left, below the Skew T diagram, is the thermodynamic profile. This contains many stats which are useful. First is CAPE, or the "storm fuel", the convective energy available for a storm to tap into. It is measured at the surface (SFC), the Mixed Layer (ML), the Forecasted CAPE (FCST) <I've read this should only be used in the morning, because it forecasts the afternoon CAPE for that day, and at other times in the day, this is not representative of the actual CAPE.>, and the Most Unstable parcel (MU), which often overestimates the actual CAPE but is sometimes useful. Next, the CINH measures the cap on the atmosphere, if any. The LI, or Lifted Index, is a useful single metric that shows the relative buoyancy of a parcel of air and the instability of the atmosphere as a whole. The LCL, LFC, and EL all give measures of how parcels rise through the air and can correlate roughly to the cloud base and height. PW is precipitable water, and measures how much water can be squeezed out of the air. You can see the Relative Humidity in the lower levels and mid levels as well. DCAPE is a measures of Downdraft energy and is strongly related to the likelihood of microbursts and severe downdraft winds, with numbers of 800+ bad and 1200+ very bad. The Lapse Rates at various levels are shown in the bottom-left and is super important to measure the instability of the air and the ability of the atmosphere to create severe weather. Finally, there's the Composite indices for severe weather - the Supercell parameter, the different Significant Tornado Parameters, and the Significant Hail Parameter. There's a lot of other statistics here as well. Maybe other posts can illuminate them!

8) Kinematics: To the right of the Thermodynamics profile is the Kinematics profile. Here, you can find the Storm Relative Winds, Storm Relative Helicity, and Shear metrics (measured in knots) at various levels, as well as bulk shear. Bunkers Right and Bunkers Left are shown here, too, for right-moving supercells and left-moving supercells. (To get expected storm motion, add 180 degrees to the given degrees - so in this example, Bunkers Right is 255 degrees, so swing that around the circle 180 degrees (in this case you actually have to subtract 180 degrees to remain in the 0-360 range), and you get 75 degrees, or basically East-North East for the expected storm motion. You can check this by looking at the white line in the Storm Slinky, which also shows this.) The second number next to the degrees in the Bunkers Right and Bunkers Left is the expected storm motion, in knots, so the right-moving cells will be expected to move at 8 knots, or about 10 mph. The Confidi upshear and downshear vectors are given, too, and these (from my understanding - please feel free to correct me!) give the expected speed/motion of propagating squall lines (like derechos) and back building setups. Finally, wind barbs give a quick glance at the winds at 1 km and 6 km.

9) The Soundings Analog Retrieval System: This gives two mini-displays, one for Supercells, and one for Significant Hail. Both use ~1000 or so historical soundings and serve up any close or semi-close matches to the current sounding. The Supercells version shows matching supercells of non-tornado variety ("NON"), weaker Ef0-EF1 tornadoes ("WEAK"), and stronger more established tornadoes ("SIG") of EF2 and greater. If you're using the SharpPy program, you can even click on each one to view the actual sounding it comes from (you can't really do this on the website-hosted versions). The Significant Hail version shows soundings that had significant severe hail, along with the size of the hail reported, in inches. At the bottom of each inset, if there is any matching data, it will name how many loose or close matches there were, along with probabilities in that set of (for tornadoes) EF3 and higher tornadoes and (for hail) 2-inch or higher hail. Since the SharpPy program lets you view the actual soundings to compare, this entire feature is much more useful in SharpPy than in website-hosted versions.

10) Significant Tornado Probabilities: This final display in the bottom-right shows the box plots of historical tornadoes versus the current STP value. Look and see where the horizontal colored line intersects the box plots for the most probable tornado strengths. The inset in the top-right also breaks apart the components of the STP calculation and shows probabilities of significant tornado in a supercell based on each component. Each box plot's center is the median STP value for each tornado strength in the historical database used, with the boxes denoting the middle 50 percent of STP values for each strength. The vertical lines (or "whiskers") extending from the boxes are outliers.

==============

There's my summary! Feel free to add to it, explain other statistics, correct anything, etc. I'm hoping this helps make Soundings accessible to more enthusiasts like me! They truly are a wealth of information and invaluable for looking at models and observations.
Man, this is so helpful. I appreciate this!
 

wx_guy

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Dude, this is great. Hopefully I'll be able to start pursuing higher education in meteorology this year, but for now I have this thread lol. Thanks!
Yeah, for sure! Happy to contribute!
 

Austin Dawg

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Thanks I plan on coming back to this and studying it when I have more time. Thanks a lot.


ETA - I finally had a chance to read this tonight or to come in on making a very complicated graph a little easier to read for those of us at home in the armchairs and recliners.
 
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catatonia

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Thank you so much for this. Soundings can be intimidating to look at ... like you wrote, there's so much data packed into one to decipher ... but it's real handy to have this summary.
 

joshoctober16

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so ive been wondering a few questions about the sounding...

1: what is best to check if the storm clouds will look more like this (super sharp puffy outline)
1707850411179.png
and less like this? (fuzzy less dense less puffy)
1707850557211.png
ive seen the super puffy type during very cold weather sometimes.

2:What makes a storm have more chance of having lightning? i have notice massive 3000+ cape days with barely any lightning and there are days with just 400 cape with a lot of lightning...

3:Bow echo/QLSC/Outflow bust days , is there any way to know if situations where all the storms will all get close and be all outflowish like the famous may 20 2019? i barely see any blue sky bust risk , but i sware the outflow, cluster bust risk days are getting more common...

4:missing info...
pretty much theres 2 that theres like no way to check them and there both seen here.
1707851012377.png
where is the LR 0-1 km? and how can i check the surface relative vorticity? im asking this because ive seen days in my area that could be very landspout prone if i could know if the 0-1 km lapse rate and surface vorticity can be found..... (this winter, during a very cold day and with snow showers every other thing that wasn't the 0-1 km lapse rates or SRV were max out for non supercell tornadoes, i also remember seeing rotation in the sky and a small funnel)

5:future parameters
while there are the 2 things i mention above, there is likely something else that could be helpful for the future and its right here
1707851380934.png
adding a SFC-0.5km spot, im hearing it could be a new useful thing to have.
 
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