[--MAIN HOME--] [--ALL HABYHINTS--] [--FACEBOOK PAGE--] THE JET STREAM AND SUPERCELLS METEOROLOGIST JEFF HABY The jet stream is an important component to supercell enhancement and propagation. The ingredients for a thunderstorm are moisture, instability and lift. A supercell has an extra ingredient of wind shear. The jet stream produces strong vertical wind shear. The low levels of the troposphere may have winds 2 to 3 times as less as the wind in the core of the jet. When a thunderstorm develops, the top of the storm will feel a stronger wind than the base. This tilts the thunderstorm as it rises in the vertical. Tilting of storms make them more potentially severe because the updraft is displaced from the downdraft. When the updraft is displaced from the downdraft, the updraft will not be cancelled by the downdraft. Shear is enhanced even further if the low-level winds are more than a 40-degree directional difference from the jet stream winds. A veering profile with southerly winds in the low levels and westerly winds aloft in a strong wind environment will produce a large directional shear. Being in a favorable quadrant (right rear or left front) of a jet streak is often over-rated. Supercells can form in any quadrant of a jet streak. Thermodynamic instability, moisture convergence, and low level lifting (WAA, fronts, etc.) may far outweigh any convergence produced aloft by the left rear and right front quadrants of a jet streak. This is especially true for low-topped mini-supercells. The middle and upper level wind is the steering wind for storms. Supercells tend to follow about 30 degrees to the right of the mean 700 to 500 millibar wind.