Windhoek — Conveniently, "weather" happened on the eve of going to press. Wednesday morning's skies revealed a persistence of the recent favourable cloud patterns, but with a difference.

Early morning observation saw low cloud, orographic cumulus, above the Auas Mountains. This mass of moist air is typical of a summer pattern and not much was expected of it but before midday, active cumulus build-up was widespread: with a few raindrops.

Persistent inflow of moist air from both the Gulf of Guinea area and mid-subcontinent was maintaining the build-up. Convergence of the two inflows was to complement this potential.

Conditions over a relatively small area covering the Windhoek valley and its surrounding mountains sparked a storm typical of a summer weather pattern. A similar out-of-season pattern also created the unexpected inflow of the moist year.

White streaks showed the presence of hail across Katutura and the Northern Industrial Area marking the beginning of the real storm. Rain accentuates the visible activity of the high-above-ground convection and turbulence within the cumulonimbus cloud.

For the next 60 minutes, the storm cell moved southeast across central Windhoek and faded.

The storm intensity and the large individual drops indicated the air mass' tropical source.

Reports of 21mm and 20mm top the list while measures above 10mm extended from Eros and southwards. The western suburbs were on the edge though with 7mm or so.

From detail to hand, this is the most prominent event recorded during this current season.

Was this the wettest ever for Windhoek? No, but it does make May 2009 an outstanding month in Windhoek.

Still too early to call since May is now only halfway, it may eventually turn out wetter than 1921, the wettest May on record so far.