bunkers_storm_motion

metpy.calc.bunkers_storm_motion(pressure, u, v, height)

Calculate right-mover and left-mover supercell storm motions using the Bunkers method.

This is a physically based, shear-relative, and Galilean invariant method for predicting supercell motion. Full atmospheric profiles of wind components, as well as pressure and heights, need to be provided so that calculation can properly calculate the required surface to 6 km mean flow.

The calculation in summary is (from [Bunkers2000]):

• surface to 6 km non-pressure-weighted mean wind

• a deviation from the sfc to 6 km mean wind of 7.5 m s−1

• a 5.5 to 6 km mean wind for the head of the vertical wind shear vector

• a surface to 0.5 km mean wind for the tail of the vertical wind shear vector

Parameters:

• pressure (pint.Quantity) – Pressure from full profile

• u (pint.Quantity) – Full profile of the U-component of the wind

• v (pint.Quantity) – Full profile of the V-component of the wind

• height (pint.Quantity) – Full profile of height

Returns:

• right_mover ((pint.Quantity, pint.Quantity)) – Scalar U- and V- components of Bunkers right-mover storm motion

• left_mover ((pint.Quantity, pint.Quantity)) – Scalar U- and V- components of Bunkers left-mover storm motion

• wind_mean ((pint.Quantity, pint.Quantity)) – Scalar U- and V- components of surface to 6 km mean flow

Examples

>>> from metpy.calc import bunkers_storm_motion, wind_components
>>> from metpy.units import units
>>> p = [1000, 925, 850, 700, 500, 400] * units.hPa
>>> h = [250, 700, 1500, 3100, 5720, 7120] * units.meters
>>> wdir = [165, 180, 190, 210, 220, 250] * units.degree
>>> sped = [5, 15, 20, 30, 50, 60] * units.knots
>>> u, v = wind_components(sped, wdir)
>>> bunkers_storm_motion(p, u, v, h)
(<Quantity([22.09618172 12.43406736], 'knot')>,
<Quantity([ 6.02861839 36.76517865], 'knot')>,
<Quantity([14.06240005 24.599623  ], 'knot')>)

Notes

Only functions on 1D profiles (not higher-dimension vertical cross sections or grids). Since this function returns scalar values when given a profile, this will return Pint Quantities even when given xarray DataArray profiles.

Changed in version 1.0: Renamed heights parameter to height

Examples using metpy.calc.bunkers_storm_motion

Sounding Calculation Examples

Sounding Calculation Examples