A guide to reading Skew-T Log-P diagrams. Temperature, dewpoint, wind shear, CAPE, CIN, LCL, LFC, EL. The classic loaded-gun supercell sounding profile and where to find current soundings.
A Skew-T (technically "Skew-T Log-P") is the chart meteorologists use to plot a vertical sounding of the atmosphere — temperature, dewpoint, wind, and humidity at every altitude from the surface to the stratosphere. It's the densest forecast tool in operational meteorology. Once you can read one, you stop guessing what the model is doing — you can see why.
Where the two traces are far apart, the layer is dry. Where they're close together or touching, the layer is moist or saturated. The shape of those near/far zones tells you where clouds form and where dry-air entrainment will eat into a storm.
Down the right side of the chart you'll see wind symbols, one per altitude. Each barb shows wind speed (number of feathers) and direction (the line points the direction wind is FROM). Reading the wind profile from surface to ~6 km tells you about shear, which determines whether storms are pulse, multicell, or supercell.
1. Surface conditions — temperature, dewpoint, wind at the bottom of the chart. 2. Cap strength — sharp warm-nose at 700-850 mb? If so, storms unlikely until convergence/heating breaks it. 3. Moisture profile — dewpoint and temperature traces close in the low levels (humid)? Then divergent in mid-levels (dry-air aloft, the "loaded gun" sounding)? 4. Shear profile — do the wind barbs change direction with height (directional shear) and increase in speed (speed shear)? Both needed for supercells. 5. CAPE — eyeball the size of the positively-buoyant area.
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