United States

A duo of storm systems is pushing inland along the Pacific coast with areas of rain, cooler air and thunderstorms.

The storms will move inland over the West thanks to a plunge in the jet stream, which is a zone of steering winds high in the atmosphere.

The dip in the jet stream will allow much cooler air to press eastward across the West through the end of the week.

Areas from Los Angeles and San Diego to San Francisco, Portland and Seattle along the West Coast will partake in the rain, as will many inland cities in the West.

Southwest Storm

As the more southern of the two systems moves inland today, the combination of moisture and plunging temperatures in the upper levels of the atmosphere can bring locally heavy rainfall and small hail, as well as locally gusty thunderstorms in California and the Southwest.

A waterspout could be produced along the Southern California coast.

Snow levels will be very high, above pass levels in California with the storm system. By the time it is cool enough for snow at the passes, the moisture will have left most areas.

While much of the moisture will be squeezed out over the Sierra Nevada, some moisture in the form of spotty showers and thunderstorms will reach across the deserts and into the southern Rockies today.

It is possible that a few of the storms will become heavy enough to even cause hail, isolated flash flooding and locally damaging wind. This could occur as far south as the Mexico border in California, from near and north of I-10 in western and central Arizona, and then near and north of U.S. Route 60 in eastern Arizona and New Mexico.

Southeast of this zone, it is unlikely any thunderstorm will have much moisture with it, but there can be enough wind to kick up dust and cause minor property damage.

Northwest Storm

The more northerly and larger of the two storm systems will move eastward at a slower pace.

However, that northern Pacific storm will spread areas of rain and locally heavy, gusty thunderstorms from northern California to Washington and British Columbia to the northern Great Basin and the northern Rockies today.

Snow levels will lower significantly with the storm in the Northwest and moisture will linger a while longer, when compared to the Southwest.

As a result, some snowflakes could reach pass level and a few inches of snow are possible over the high country in the Northwest.

Plains Problems

As the storm duo reaches the Continental Divide by late today into Friday, a zone of drenching rain is likely to develop over portions of the central and northern Plains with the risk of a severe weather outbreak over part of the central and southern Plains.