I think the lake effect requires air which is colder than the water. The lowermost level of air warms and accepts water vapor, which immediately rises, re-freez

I think the lake effect requires air which is colder than the water. The lowermost level of air warms and accepts water vapor, which immediately rises, re-freezes, and is entrained as ice and blown out onto land. Lake-effect precipitation does form over seas, but you need the air temperature above the surface layer to fall below zero. As for the rain in Saudi Arabia, there is a mountain range along the coast south of Mecca, and I think the area gets rain because of orographic uplift. When the wind blows across the Red Sea it does pick up a lot of moisture, just not enough to cause rain, because the air is so hot and can hold so much moisture overall. But it gets forced up over the mountains, cools, and passes saturation humidity, and the excess water becomes rain. You can see where the mountain range ends on an annual precipitation map of SA. Sorry to rain on your parade.