A large & cold winter storm with plenty of subtropical moisture will dive into the Desert Southwest early Monday setting up a rare winter storm with accumulating snowfall for St. George. The National Weather Service has issued Winter Weather Advisories and Winter Storm Warnings for Central and Southern Utah beginning at 5 AM Monday through Tuesday morning.
As this storm dives South, it will feed into the Pacific Ocean for additional moisture as the storm tracks into the Southwest. Ahead of the arrival of the winter storm, a Southerly wind flow will begin to increase helping to aid in an increase of snow and higher snowfall amounts for the South facing, upslope favored mountain ranges of Southern Utah. Unusually cold air will accompany this storm allowing for snow levels to drop below 2,000 ft by Tuesday morning.
St. George may mix with rain and snow Monday morning before switching back to all rain through the day Monday as warmer air is advected into the area. A brief break in the precipitation may occur for a time in the early afternoon before the bulk of the precipitation and snowfall arrives late Monday through sunrise Tuesday morning. At this time, the coldest airmass will be over the area allowing for all locations across Southern Utah to switch to snow.
Once the transition to snow begins, most locations will see several inches of accumulating snow, especially along I-15 North of St. George, higher mountain valleys and Southern mountains of Utah. With significant snowfall expected for most, travel will be hindered with many snow-covered or slick roads, including I-15. This will lead to a high impact winter storm as winter driving conditions are expected.
Those living in the Southern end of Washington County can expect to pick up 1-3″, including St. George, Ivins, Bloomington & Santa Clara. Higher amounts of 5-12″ are expected the farther North you travel into Washington Co., including Zion National Park. Many SW Utah cities are forecast to pick up 4-7″ with locally higher amounts and as much as 2 feet or more in the Pine Valley mountains.
Central Utah could also see several inches of snow, especially areas favored in a Southerly flow like Castle Country. A large majority of Central Utah is under a winter weather advisory through 5 PM Tuesday as light to moderate snowfall will lead to travel impacts in this area as well.
When driving in snow, it is important to allow for plenty of distance between cars, slow down, have proper tires for the conditions and if you are in a heavy snow zone, have a 72-hour emergency kit ready.
The Pinpoint Weather Team is tracking this latest winter storm and will be providing updates on-air and online throughout the storm at abc4.com/weather.