Location: Iraq, Persian Gulf
The Quas is a moderate to gale-force southeasterly wind in the Persian Gulf, most frequent between December and April, when eastward travelling winter depressions from the Mediterranean Sea moving across the Middle East become reinvigorated over warm Persian Gulf waters.
Initially dry, the warm and steady southeast wind will pick up large quantities of moisture due to its long fetch across the sea. The air-mass is becoming increasingly unstable, both by moisture input below and the arrival of the westerly upper-air through from the Mediterranean. The Quas is accompanied by gloomy, damp weather with squally thunderstorms, which will give way to rain and drizzle eventually.
After the passage of the depression the Quas is often followed by the strong southwesterly Suahili wind, which is a local name to a wind that actually belongs to the big Gibli and Sirocco family. The Quas is also called Sharki sometimes, especially more inland when it is turning dry and dusty.