A potent upper-level low will continue directing subtropical moisture over much of California today.
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Heavy coastal and low elevation rain, thunderstorms, heavy mountain snow and high winds are all expected from this Atmospheric River event.
Excessive Rainfall leading to Flash Flooding is possible for much of the state today.
A Slight Risk of Excessive Rainfall (level 2/4) is in effect from Humboldt to Orange County as well as over parts of the Sacramento Valley and along upslope portions of the Sierra.
A Slight Risk of Severe Thunderstorms is in effect for parts of the Sacramento Valley where an isolated tornado will be possible.
A targeted Moderate Risk of Excessive Rainfall is in effect for Santa Barbara and Ventura where heavy rainfall will focus, especially over elevated terrain.
Heavy Snow will blanket the Sierra Nevada and Shasta Siskiyous today as well, with those mountains forecast to receive 1-3 feet (isolated higher) of snow by Tuesday morning.
The moisture feed into California will weaken considerably and sag south on Tuesday, but the threat of Flash Flooding will persist across southern California, in particular.
Upslope flow into the Transverse ranges will support a renewed threat of Flash Flooding.
A Slight Risk of Excessive Rainfall is in effect from Humboldt down through San Diego County on Tuesday mainly due to sensitive soils from today's heavy rain.
Up to a foot of additional snow accumulations with locally higher amounts are possible over the Sierra and Shasta Siskiyous on Tuesday.
Damaging wind gusts should continue into Wednesday morning before gradually weakening.
Elsewhere, lake effect snow will come to an end this afternoon across the Lower Great Lakes.
Upper level ridging with embedded shortwave energy will support a warming trend acrosss the Great Plains and Mississippi Valley through midweek when anomalous temperatures are expected to reach their peak for the week.
High temperatures will be between 15-25 degrees above average by Wednesday over much of the central U.S. ■
A strong storm that originated over the Pacific has tracked through the Great Basin and is currently transitioning across the Rockies to redevelop across the central High Plains later today into early Saturday morning.