Temps Soar Into 90s Across Midwest

While many across the Lower 48 have been enjoying a relatively warm and dry start to autumn, Siberian snow has already been growing and may add a chill to your winter forecast.

Introduction On Siberian Snow Pack

One of these key players is Siberian snow cover, particularly early in the fall season. Increased snow cover across eastern Russia leads to increased reflection of sunlight and anomalously colder temperatures at the surface for the time of year.

As this early, unusually cold air mass builds over Siberia, it impacts weather patterns further down the jet stream across the Northern Hemisphere. The increased snow cover across Siberia is found to be connected with warm conditions across the eastern Arctic, increasing the probability of a polar vortex disruption during the winter season.

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Polar vortex disruptions are often responsible for dumping arctic air into the U.S. Lower 48. During these polar vortex disruptions, cross-polar flow can often ensue. Cross-polar flow describes the transport of frigid Siberian air into North America, and consequently, parts of the U.S.

(MORE: What Is The Polar Vortex?)

Polar vortex disruptions are one of the key culprits for severe cold waves in recent U.S. memory, and they are encouraged by increased Siberian snowpack during the fall season.

What Does the Siberian Snow Pack Look Like Today?

Snow cover across Siberia has been quickly increasing throughout September, according to Rutgers University. Today, much of the Russian interior between the Ural Mountains in the west and Pacific Coast in the east has an above-average snowpack. The few exceptions are along Russia’s Arctic Coastline in the north.

Looking ahead at the forecast, Russia will likely see a continued increase in snowpack along its southern borders with Mongolia and China with an active storm track. This will further serve to grow the extent of Siberian snow cover as we enter October.

What Else Can Control Our Winters?

While the Siberian snowpack alone does not ensure a cold winter, it is one of the key players behind our winter forecast. Other key drivers behind U.S. winters include ENSO (El Niño and La Niña) and water temperatures in the North Pacific.

Currently, NOAA predicts a 71% chance of La Niña conditions for October through December and a 54% chance for December through February. La Niña is generally indicative of warmer, drier conditions in the southern tier along with cooler, wetter and snowier conditions in the northern tier.

(MORE: What La Niña Means For This Winter)

Moreover, the North-Central Pacific is experiencing a marine heatwave, and this could cause downstream impacts on the U.S. weather pattern during the winter months. However, the extent and degree of those impacts remain unclear at this time.

With the fall Siberian snowpack off to a quick start, it is possible that any potential cold shots during the winter could be more potent, even if the North Pacific and La Niña do not necessarily support that across much of the country.

In other words, it is possible that this winter could feature frequent ‘weather whiplash’ or an alternation between warm, dry conditions and wet, cold or snowy conditions.

According to NOAA’s Climate Outlook, warmer conditions are favored this winter across the Desert Southwest, Gulf Coast and East Coast. Colder conditions are favored across the Pacific Northwest with near-average conditions being favored across the Northern Plains, Midwest and Great Lakes.

(MORE: Our October Outlook)

Hayden Marshall is a meteorologist intern and First-Year Master's Student at the Georgia Institute of Technology. He has been following weather content over the past three years as a Storm Spotter and weather enthusiast. He can be found on Instagram and Linkedin.