SBCAPE vs MLCAPE: Which One Is More Useful?
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- čas přidán 11. 07. 2024
- Brief discussion of surface-based CAPE (SBCAPE) and mixed-layer CAPE (MLCAPE), what they mean, how they differ, and why one is much more useful than the other when making a severe weather forecast.
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Awesome video. 🙂👍
Thank you!
@@ConvectiveChronicles Your welcome.
This is a great video! Would it be possible to do another one similar to this but on MUCAPE as well, please? :)
Thank you! MUCAPE is a lot simpler; it’s the CAPE calculated using the parcel that has the highest equivalent potential temperature (basically, the temperature of a parcel of which all the water is squeezed out then brought down to 1000mb). It’s only used for elevated convection scenarios. I talk about MUCAPE in this video here: czcams.com/video/BRjJsYfwUbo/video.html
Thanks for another lesson! What does the dotted red line leading up from the surface (seemingly paralleling the env. temp line) represent? I see this often but don't recall seeing it mentioned in the skew-t lessons. Thanks again!
Thank you for watching! That dashed red line is the environmental virtual temperature profile…it’s basically a slight temperature correction that takes into account moisture. In essence, two air samples with the same virtual temperature have the same density, regardless of their actual temperature or moisture content. I discuss how virtual temperature is actually calculated in the following video: czcams.com/video/pBkvpNUPDDc/video.html
@@ConvectiveChronicles Thanks Trey. That's my lesson for tonight then!. Really appreciate all of your efforts!
You bet; please let me know if you have any questions!
Thanks for this explanation - I'm a high schooler who makes weather forecasts for my friends, and when forecasting storms I certainly find MLCAPE to be more useful, and this explains why
Just a quick question: does the MLCAPE over SBCAPE rule apply for tornadoes as well? Since tornadoes are obviously surface based and can't occur in elevated storms, does that mean SBCAPE does a better job with that? Would a storm that enters an area of higher area of SBCAPE be more of a tornado threat than one that is in an area where there's less SBCAPE, given all else is equal? Or is MLCAPE still a better tool for forecasting tornadoes? Just curious, since I'm still learning
Excellent questions…I’d say that SBCAPE and MLCAPE don’t necessarily differentiate between tornadic and nontornadic environments. The value of SBCAPE by itself (and MLCAPE for that matter) doesn’t tell you whether storms will be surface based or not; instead, the overall distribution of the CAPE throughout the entire profile will help in that regard. Shear parameters have a lot more impact on how favorable an environment is for tornadoes than instability parameters do, but updrafts (i.e. storms) themselves will be more robust in higher-CAPE (including SBCAPE) environments. But again, it’s the overall distribution of that CAPE (where are capping inversions, skinny vs fat CAPE, etc.) that’s more important than the actual CAPE values themselves. Hope this helps; let me know if you have any other questions.
@@ConvectiveChronicles Thank you!
what is FCST surface? (forcast surface)
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does that mean what they THINK the peak CAPE will be? (like when the cap breaks... or during peak heating, ETC)
never find.... found it (was a hard google however..... had to "force" results that included FCST)
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an estimate of the afternoon maximum temperature is combined with the mean mixing ratio in the lowest 100 mb of the sounding. The afternoon temperature is derived from taking the parcel at 850 mb dry adiabatically to the ground, and then adding a 2 C superadiabatic "contact" layer.
Yep, exactly. I talked about that toward the end of my soundings series; I’ve never used it or seen it used in any normal severe weather application.
Hehe I am surprised I never commentated on this one before. MLCAPE is always the go to. SBCAPE has....well....it's there and I only glance at it just to be funny but MLCAPE is always gonna be the go to.
Do you look for a MLCAPE value to be greater or equal to a number to signify a favorable environment for tornadoes? What value would that be?
There isn’t really a threshold value of MLCAPE for tornadic activity…it all depends on the setup. I’ve seen tornadoes occur with 100-200 j/kg, and I’ve chased setups with 7000 j/kg that don’t produce much at all.
@@ConvectiveChronicles Gotcha I didn't know if it was like 3CAPE where you said greater than or equal to 50j/kg. Thank you!