SKEWT: A LOOK AT 03 KM SHEAR
 
METEOROLOGIST JEFF HABY
1. What is 03 KM SHEAR?
03 KM SHEAR is
speed shear between the surface and 3 km above the surface.
2. How is 03 KM SHEAR determined?
The formula is the change in wind speed (m/s) divided by the change in distance (m). This number is then multiplied by
1000 to simplify the number. The units come out to s^1. These units result from m/s divided by m.
Example: The surface wind speed is 7 m/s while the wind speed 3 km up is 25 m/s. This gives a change in
wind speed of 25  7 = 18 m/s. The change in distance is 3 km = 3,000 m
18/3,000 = 0.006 s^1 * 1000 = 6 units of shear
3. Operational significance of 03 KM SHEAR:
0 to 3  Weak 
4 to 5  Moderate 
6 to 8  Large 
8+  Severe 
UPDRAFT: Speed shear
tilts a storms updraft thus increasing its longevity.
HELICITY: Strong speed shear is one factor than leads to high Helicity values.


