Why does western Washington see fewer thundershowers than elsewhere in the United States?
Keep in mind that thundershowers require moist air to be lifted; that source of lift, or rising air, often comes from much warmer air near the ground compared to air higher in the atmosphere. It bubbles up through the cooler air aloft like a hot air balloon. Most of our disturbances (especially those capable of generating heavy showers) move from off the Pacific ocean. The sea surface temperatures are cool there, typically in the fifties. Not the stuff typically capable of generating lift. By contrast, the steamy air masses that produce thundershowers from the Rockies east move off the Gulf of Mexico, where the water is much warmer-in the seventies to near eighty degrees. Now we certainly see some thundershowers here...usually when the ground warms and much cooler air moves in aloft.
