Jackson, MS sounding

KJAN · 00Z Oct 7 launch · 101 m elevation

The 00Z Oct 7 launch on a Skew-T log-p, the key drawn on it. The hodograph is the wind through the lowest six kilometres, coloured by height: red near the ground, amber to three kilometres, green above. The 12Z Oct 6 launch is the faint trace behind it.

Barely any instability with little to hold storms down (CAPE 3 J/kg). The column is moist. The freezing level is about 14,700 ft up.

CAPE: 3 J/kg · none
CIN: 0 J/kg · weak cap
LCL: 892 hPa · 18.9°C
Lifted index: -4.9 · unstable
K index: 33.1
Precipitable water: 41.8 mm

Reading a sounding

A radiosonde goes up on a balloon twice a day and reports temperature, humidity and wind all the way through the atmosphere. On a Skew-T the temperature axis leans right as you go up, so a parcel of air rising without exchanging heat - the faint purple lines - runs nearly straight up the page, and the gap between the red temperature trace and the green dewpoint trace is how dry each layer is.

CAPE is the energy a surface parcel would pick up rising through the profile: the area where the dashed parcel path sits to the right of the red trace. CIN is the energy holding it down first - the cap. The hodograph is the wind with height; a curve that turns clockwise with height is what rotating storms are made of.

Nearby launches

Slidell, LA Birmingham, AL Little Rock, AR Shreveport, LA Lake Charles, LA Peachtree City, GA

Source: National Weather Service radiosonde observations for KJAN, via the Iowa Environmental Mesonet RAOB archive. Indices are computed here from the surface parcel and can differ from SPC’s.