U.S. Winter Storms February 2021

First Posting | Summary
Posting Date: February 18, 2021, 6:30:00 AM

From February 13 through February 16, several atmospheric phenomena combined to wreak havoc across the continental United States, the likes of which has not been seen in many years.

Meteorological Analysis

Weeks beforehand, part of the polar vortex broke loose and began traversing the northern United states. This pool of extreme cold air remained stationary for days in southern Canada as a low-pressure system moved onto the West Coast. At the same time, a large-scale atmospheric teleconnection called the Arctic Oscillation, which had been negative all season, reached its most negative value of the season around mid-February. When the Arctic Oscillation (a reflection of pressure differences farther north by the North Pole) becomes negative it favors a weaker more meandering jet stream, meaning storm systems will move farther south. 

As a result, the low-pressure system from the West Coast weakened and redeveloped past the Rockies and in a somewhat unusually southern location—in the Gulf of Mexico off the coast of Texas. Given the cyclonic, or anti-clockwise flow of these systems, this allowed the cold pool of air sitting across the Northern Plains and southern Canada to be funneled down into the Sun Belt and Texas region. The result was a storm somewhat weak in pressure (only  dropping  to 992 mb) but loaded with plenty of cold air as well as moisture from the Gulf that caused snowfall and ice across a region normally spared these events. As the storm moved east and north, it took this cold air, lift, and moisture across the Southeastern and Mid-Atlantic states, allowing for severe weather of both the summer and winter variety. 

U.S. Snow and Low Temperature Records Fell

This combination of atmospheric ingredients resulted in 39 of 48 continental U.S. states to fall under some type of winter weather advisory or storm alert—the largest region under a winter storm warning since 2005. Farther north, the brutal cold and wind resulted in wind chills of -10° to -30°F.  Although the storm was physically very far away, this abnormally cold air, blowing over the Great Lakes, caused substantial lake effect snow in the Chicago and Indiana lake towns, which resulted in more than 1 to nearly 2 feet of snow in these locales. More than 2,000 cold temperature records were set, from New Orleans (25°F, record was 29° in 1993) to Dallas (-1°F, record was 12° in 1903) to -31°F in Lincoln Nebraska. Wind chills in the Dallas region reached as low as -15°F and between 3 and 6 inches of snow blanketed the area. Farther east, the storm’s cold front caused severe thunderstorms and tornadoes in Georgia, North Carolina, and Florida. In regions where not only warm air worked in aloft from the storm's southerly flow, but also abnormally cold yet shallow air remained close to the surface, ice accumulated instead of snow. Ice accretions were found from Oregon City, which received 1.5 inches of ice, all the way through to the Southeastern states of Louisiana, Mississippi, Tennessee, and Kentucky, where 0.5 inches of ice accumulation was found.  

With more than 100 million Americans affected, as of February 16, the country set a new record for the largest area of the United States ever blanketed in snow, 73% of the nation (since 2003 satellite records were kept). From Washington to Maine, the winter storm of mid-February 2021 is a strong reminder of the shear mass (and scale) of disruption and destruction that extratropical cyclones are capable of. 

Reported Damage and Disruption

Southern states in particular are poorly equipped to deal with severe winter conditions. Unplowed or icy roads and overpasses have led to innumerable accidents throughout the Deep South and Midwest. Many major highways have been closed either because of blockages caused by multi-vehicle crashes or to prevent them from occurring. Air travel has been seriously affected, with thousands of flights from multiple airports canceled.

Power outages impacting at least 10 states from Louisiana to Oregon have been widespread, and in some locations prolonged. The extreme winter weather is directly to blame for some, but others have been rolling blackouts implemented to prevent further, more widespread, and uncontrolled outages following unprecedented spikes in demand.

Texas

Governor of Texas Greg Abbott had issued a disaster declaration in all 254 counties on February 12; U.S. President Joseph R. Biden, Jr., approved the Texas emergency declaration on February 14. Texas, the only state to have its own grid, has been particularly badly hit, with more than 4.3 million outages reported at the peak and more than 2.8 million without power as of February 17, until 8,000 megawatts were added to the Texas grid, enough power for about 1.6 million customers, according to the Electric Reliability Council of Texas. More than half a million customers in Texas remain without power today, according to PowerOutage.us. Dozens of shelters that had been opened to warm Texas residents had to shut due to power loss.

Power supply issues led to major water line breaks in Galveston, Texas, and the imposition of a “Stage 5” water restriction; once supplies are restored, the city will have to issue a boil water notice. Oil wells and refineries, including the largest in the U.S. (The Motiva Enterprises complex in Port Arthur) have shut down operations because of the low temperatures and power outages. Natural gas and other pipeline operations have also been affected. Even agriculture has not escaped unscathed. In Texas—a major producer of citrus fruit—the grapefruit harvest was only half complete when the cold weather struck, for example, but it will be several weeks before the damage done can be assessed.

COVID-19 Complications

The extreme conditions have also impaired the COVID-19 response. The Centers for Disease Control and Prevention warned of likely widespread delays in the shipping and distribution of vaccine because of treacherous travel conditions impacting the major shipping hubs of Memphis, Tennessee, and Louisville, Kentucky. Many vaccination appointments have been canceled across the country because clinics have had to close and/or because of these supply issues; in Miami-Dade County, for example, about 2,000 appointments for a second dose were postponed. Southern states have fared worst, but even in New Hampshire appointments on February 16 had to be rescheduled or canceled. And in Texas a public health facility rushed to use 8,000 doses of the vaccine before they spoiled after it lost power and its backup generator also failed.

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Posting Date: February 18, 2021, 6:30:00 AM