The Nation's Weather 07.21.09

By WEATHER UNDERGROUND (AP)

Severe weather was expected to track through the Central Plains and into the Mid-Mississippi River Valley on Tuesday.

Forecasters called for a strong low pressure system developing over the Central Rockies to continue kicking up severe weather and pull warm and moist air in from the Gulf of Mexico. Flow around this system was forecast to create a warm front capable of triggering heavy showers and thunderstorms with periods of heavy downpours, strong winds, and hail. Tornado development was likely with this system. The strongest storms were anticipated to track through Missouri with new rainfall amounts between 1 to 2 inches, while scattered showers were forecast to extend from the Mississippi to the Central and Southern Plains.

Meanwhile, in the East, a trough was expected to linger over the East Coast due to a hovering ridge of high pressure sitting offshore. Forecasters didn't expect this ridge to allow storm propagation or for scattered showers to persist over the coasts of New England. They expected new rainfall amounts of less than a quarter of an inch with more in areas of thunderstorm development. The Southeast was expected to continue to see hot and humid weather with highs in the mid-90s, however, scattered shower and thunderstorm development wasn't likely.

In the West, high pressure was forecast to continue dominating the weather across the West Coast. The Pacific Northwest was expected to reach into the 80s again, while Southwest should surpass 100 degrees again on Wednesday.

Temperatures in the Lower 48 states Monday ranged from a low of 31 degrees at Stanley, Idaho to a high of 125 degrees at Death Valley, Calif.