ARPS(Advanced Regional Prediction System )Version 4.5.1.

Center for Analysis and Prediction of Storms (CAPS), Oklahoma University

•tridimensional• compressible • non hydrostatic• resolution 1km •Navier-Stokes equations• Generalized coordinate systemParameterized microphysics (Kessler and Lin)

Main Equations

•Prognostic equations for u, v, w,, p’ and Where: : water vapor, cloud water , rain water, cloud ice, snow and hail (graupel)•Equation of state

SqGDqGqV

qW

qv

quq

t

q

c

))(

(

)(

*

*

****

Conservation equations for mixing ratios (vapor qv,

cloud water qc , rain water qr, cloud ice qi, snow qs

and hail qh.)advection

sedimentation mixing

Sources (microphysical processes)

General simulation parameters.

• Domain: 90x96x20 km • Horizontal Resolution : 1 km• Vertical Resolution : 0.5 km • Time Resolution: 6 s• Lateral Boundary Conditions: Open (Klemp and

Wilhemson, 1978) • Top and Bottom B.C. Zero normal gradient• Considered:

Orography, Radiative effects, Land Use, Coriolis.

July 2, 2001 Severe storm

Convection initiated with an ellipsoidal perturbation

Θmax= 4KCentral coordinates: x=50 km, y=37 km, z=1.5 kmDimensions: 10x30x1.5 km (Simulating the form and

dimensions of a preexisting storm)

•Control output : every 60 s

•Total simulation time: 3 h

• Environment:

• Radiosounding 13:00 LST

• Camagüey, Cuba (21°25' N , 77°10' W)

Domain:

Camagüey, Cuba (A 90 x 90 km square, with lower-left vertix at 21°25' N , 77°10' W)

Domain:

Camagüey, Cuba (A 90 x 90 km square, with lower-left vertix at 21°25' N , 77°10' W)

Sounding for July 21, 2001

Hodograph

t = 30 min., t = 50 min., t = 70 minVertical Vorticity (x 10-5 s-1), z = 6 km

w(m/s)

Vertical Vorticity, z = 9 km

t=50 min, z=9 km t=70 min., z=9 km

Reflectivity (dBZ)n and w (m/s)

W(m/s)

32

48

48 60

qc and qR (g/kg) for the Wmax. slice in the Y-Z plane

qi and qH (g/kg) for for the Wmax. slice in the Y-Z plane

qc and qR (g/kg) for theWmax. slice in the Y-Z plane

qi and qH (g/kg) for theWmax. slice in the Y-Z plane

Trajectories of the centers of both cells and the center of the system. Point labels indicate simulation time.

Left moving cell

Center of the system

Right moving cell

Left moving cell

Center of the system

Right moving cell

CAPPI

3-4 km

CAPPI

9-10 km

CONCLUSIONS• Low precipitations supercell system, generated in

an environment of high instability, and clockwise turning hodograph with low wind speeds at the lower levels and strong, and nearly unidirectional wind shear at heights from 6 to 12 km.

• Split storm structure, more clear at upper levels• Left moving cell disspated by the entrainment of

cold air, generated in the central downdraft at low and middle levels, conditioned by the wind profile.