Hodograph

The hodograph plots wind speed and direction for every wind observation, and it connects them with a trace that is color coded by height of the observation. Wind vectors are mentally visualized by imagining a line drawn from the center of the origin to a point on the hodograph trace.

The hodograph contains the following primary features:

x-axis - east-west wind directions relative to the origin with the convention of 90 degrees to the left of the origin and 270 degrees to the right of the origin

y-axis -north-south wind directions relative to the origin with the convention of 180 degrees above the origin and 360 degrees below the origin

white rings - wind speeds every 20 kts

red line - wind observations from surface-3km ASL

green line -wind observations from 3-6km ASL

yellow line - wind observations from 6-9km ASL

cyan line - wind observations from 9-12km ASL

purple line -wind observations from 12+ km ASL

cursor readout (top) - wind direction (degrees) and speed (kts and m/s) at the cursor position are displayed in blue at the top of the hodograph

Critical Angle (bottom) - angle (degrees) between the surface storm-relative wind (SRW) and the sfc-500m shear vector

Large Critical Angles imply large values of streamwise vorticity near the ground and an enhanced potential for low-level rotation.