Bitterly Cold Temperatures

      The prolonged period of bitterly cold temperatures is setting numerous records across the central and eastern U.S. A long-lived Arctic outbreak has brought dangerously cold conditions to much of the central and eastern United States since Christmastime and will continue through this week.

This prolonged cold spell has already been notable for several reasons, including its severity, duration and widespread impacts. Wind chill warnings and advisories stretched from the Canadian border in the northern Plains to the Gulf Coast which is not something you see every day. It was minus 58 degrees in Hettinger, North Dakota last Sunday morning. These cold temperatures have a number of effects.

      The frigid weather is the byproduct of a bomb cyclone and polar vortex and wind chills in one part of New Hampshire were forecast to hit negative 100 degrees. The wind steals your breath and freezes your eyelashes. Cold stabs your face and numbs your earlobes to rubber. Toes and fingers, including those wrapped in multiple layers of clothing, can quickly go numb and the wind turns snowflakes into projectiles that feel as if they are piercing any skin that is exposed.

      The cold weather can affects one's blood pressure. Lower temperatures narrow the blood vessels, which elevates blood pressure. The constriction of blood vessels in colder conditions is actually a survival mechanism that helps conserve heat and maintain body temperature, it provides less room for blood to move around.

      According to a 1961 study on seasonal variations in blood pressure it was found that cold weather can increase a person’s blood pressure. It was also found that low temperatures are strongly associated with increased hospital admissions for acute heart attacks, stroke and result in higher cardiovascular mortality. How much blood pressure increases in cold weather depends on variables including the current temperature, wind chill, how long a person is exposed to colder weather and the person’s health.

     University of Florida researchers found that being exposed to a temperature of 52 degrees Fahrenheit for only five minutes can cause a significant increase in blood pressure. Blood pressure elevations in winter were highest among people aged 80 and older. To combat the impact of lower temperatures on blood pressure, guess what the recommended solution is? Keep warm.

      Another side effect of extreme cold temperatures is the vulnerability of power systems. Sometimes the power goes out, but why would power go out when it’s cold outside? The electric system consists of thousands of components that are mostly electro-mechanical, with lots of moving parts and these systems work best when they operate in the middle of the temperature and moisture/humidity range they were designed for.

      When they are new, these devices are designed and rated to operate correctly in even extreme temperatures. But as they age they may not operate well in extreme conditions. When it gets too cold, hot, or moist, many of these devices operate slower, faster, or less predictably than they normally would especially when they are called upon to perform really hard work, such as a circuit breaker or switch opening fast enough to protect the system from a short circuit caused by a tree branch falling on a line.

      Trees and other nearby items can pose a threat to power lines. But even if there is no snow and ice to send branches tumbling onto the above-ground lines, tree roots can cause problems by providing a pathway for ice to build up around lines underground. In both cases the lines are already stiffer than usual from the cold, making them more vulnerable.

      Wind can also cause problems by blowing tree limbs into lines or rocking trees hard enough to have the roots of the trees rub against the underground lines. Over 40 percent of outages come from trees, and another 20 percent come from animals. In cold weather, a warm transformer can be very inviting to a small animal or bird, which can result in malfunctions.

      Another issue with extreme temperatures is that consumer demand for energy is higher. This can result in local or widespread overloads that may cause service to some areas to go offline or switch to rotating blackouts.

      The polar vortex isn't the only reason for these cold temperatures. A polar vortex is a swirling mass of frigid air typically found over the Arctic that occasionally ventures southward. But the vortex is just one of the culprits.

      The jet stream is a river of wind that typically sits about 20,000 feet (6,100 m) or more above the Earth's surface and influences how air masses and weather systems are distributed. The jet stream guides weather systems across the country and also separates warm air masses in the South from those cold air masses in the North. When the jet stream is north of a particular location, that region usually experiences mild weather because the jet stream is blocking the cold air. But when the jet stream has plunges south the cold air generated by the polar vortex has plunges with it.

      The “bombs” are low pressure systems thatbcause a strong bend in the jet stream pattern, forming a sort of slide through which cold air from the Arctic whooshes down into states east of the Rocky Mountains.