From the science director summary Note the location and orientation (SW-NEish) of the storm cloud

From the science director summary Note the location and orientation (SW-NE-ish) of the storm cloud

WRF Upward moisture flux at surface; 10m wind vectors 15/07/07 11Z

Upward moisture flux at surface; 10m wind vectors 15/07/07 12Z

Upward moisture flux at surface; 10m wind vectors 15/07/07 13Z

Upward moisture flux at surface; 10m wind vectors 15/07/07 14Z

Upward moisture flux at surface; 10m wind vectors 15/07/07 14Z Wind starts to veer to the south

Upward moisture flux at surface; 10m wind vectors 15/07/07 14Z Relatively high upward moisture flux Convergence lines forming

Upward moisture flux at surface; 10m wind vectors 15/07/07 15Z Strong convergence; relatively high upward moisture flux “upwind” of the convergence line

Upward moisture flux at surface; 10m wind vectors 15/07/07 16Z Strong convergence; relatively low upward moisture flux “upwind” of the convergence line

15/07/07 14Z Upward moisture flux at surface

Landsat 7 Image: exact same coverage as previous slide Date of image: unknown Note fair weather cumulus in the same location as the 15/07/07 convergence line. Is this a persistant feature?

10m wind vectors over orography with cross-section of W over the convergence line; 14Z +ve vertical velocities not appreciable above 5km Wave-like features +ve W -ve W

Summary Initial impressions suggest that for WRF There is a strong convergence zone in the region of the observed cloud. The convergence line has a similar orientation to the cloud signature seen in the remote sensing data. This convergence zone forms about 13Z and persists until 16Z; however, at the latter time, the upward moisture flux in the region of the convergence has dropped dramatically. This agrees with reality: the cloud had diminished by 16Z The convergence is caused by wind veering to the north- west of where we expect the cloud to be. Flow chanelling? Flow blocking?