Weekend weather blog: Breaking down our cold and active stretch of weather

The temperature can affect the texture of the snow
Published: Dec. 26, 2021 at 5:30 PM MST
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TWIN FALLS, Idaho (KMVT/KSVT) — Just in time for Christmas, a storm system brought in some snow during the morning hours of Friday. Areas saw as much as 4 inches by the time the sunset on Friday. And before we knew it, yet another system made its way into the area for Christmas morning.

This dropped another 1 to 2 inches of snow for those of us in the Magic Valley, with higher amounts in the South Hills and Wood River Valley. After a little break on Saturday afternoon, yet another quick inch or two (with higher amounts in the Wood River Valley and South Hills) fell late Saturday night and early Sunday morning.

Snowfall over the last 72 hours (NOAA)
Snowfall over the last 72 hours (NOAA)(NOAA)

Above, you can see the total amount of snow that fell over the last 72 hours. Twin Falls, between all three events, saw around 6 inches, with peaks in Blaine county seeing at least 30 inches and peaks of the South Hills such as Pomerelle seeing up to 2 feet.

And yet, there’s more snow on the way. What’s with this pattern bringing us so much active weather and cool temperatures. To understand this, we need to look above the earth’s surface, up much higher in the atmosphere.

Rap 500 mb analysis (NAS) (Pivotal Weather)
Rap 500 mb analysis (NAS) (Pivotal Weather)(Pivotal Weather)

The above image shows atmospheric energy and pressure aloft. Within the three circles are three energy maximums that came through - the one over eastern South Dakota being the remnants of Friday’s system, the one over Wyoming the being remnants of this morning’s system, and the one-off the Washington/Oregon coast being a system expected to come through late tonight and tomorrow.

There’s one common theme with each system - they’re rotating around a large upper level arctic low pressure. These types of large-scale aloft low-pressure systems can stay stationary over an area for quite some time, allowing multiple smaller-scale changes in pressure to generate storm systems that rotate around them.

Eventually, the energy associated with these large-scale features allows them to slowly but surely track eastward. As the center of this particular system begins to track eastward, very cold temperatures associated with the area of low pressure will move in with it.

This is expected to happen in a few days. So what will be the end result at the surface? very cold temperatures after 1 or 2 more rounds of snow. By Tuesday morning, much of the region will likely see 1 to 3 additional inches of snow, with temperatures only reaching into the lower teens for highs - even in the Magic Valley.

The upper-level low will, fortunately, continue to move off to the east by the end of the week, bringing some slightly warmer temperatures in for Friday. However, it looks like another setup like this will be expected for the end of next weekend into the beginning of next week.

Needless to say, it’s going to be feeling ice cold with the pattern that will continue to impact us in the short and mid-term. It may be a good time to sit inside next to the fireplace and drink some hot cocoa while you can. 2021 has definitely been a year of extremes - and the last week is certainly looking like the year of extremes will close out with a bang.

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