According to AboutEducation.com, Heat Waves are a series of days or temperatures that create a safety hazard for anyone exposed to the heat. A heat wave can be an extended period of days with higher than normal temperatures. A heat wave can also be shorter in length, but with abnormally high temperatures.
There are 4 Environmental Factors that help cause Heat Waves. These factors are:
- Absence of polar air masses that might move into the region.
- Strong surface heating, typically occurring when the sky is clear during the summer time.
- Dry conditions on the ground.
- Intensity of surface heating and limited vertical mixing.
Absence of Polar Air Masses
One reason the absence of polar air masses helps create heat waves is due to the fact that a Jetstream separates polar and tropical air. When the Jetstream is far to the North, this means that polar air masses stay further north. For Anchorage, this might need to be further North than it typically is for the continental US states.
Strong Surface Heating
Cloud free skies under high pressure allow for the formation of a warm air dome, which adds to a heat wave. Because of this, strong solar heating plus subsidence create strong surface heating.
Dry Conditions on the Ground
If less energy goes into evaporation cooling, then more energy is available to heat the ground. Also, what helps add to heat waves are drought conditions (which we will talk about in another blog post) that lead to a rapid heating, further drying the ground.
Limited Vertical Mixing
Most heat waves are characterized by a strong inversion at altitudes from 1-3 km. If the air below the inversion is hot and moist, the trapping of air near the surface will lead to a perpetuation of high heat indices at the surface.
The problem with finding a definitive definition is that a heat wave is relative based on the city, region, or type of heat experienced during this “wave.” However, typically a heat wave occurs over the warmer summer months, when temperatures are already high, causing problems to the city and citizens due to even higher temperatures.
According to US Climate Data, in Anchorage, the average high temperature year-round never reaches higher than 65 degrees Fahrenheit. This is much different than other cities in the U.S., Phoenix for example, where average high temperatures don’t creep below 66 degrees Fahrenheit. There might be temperatures in these cities that fluctuate, but for the most part the highs over the course of the year remain similar.
Determining a heat wave for Anchorage doesn’t seem as hard as it would be for Phoenix, as temperatures have occasionally reached in the 80s, which have been cited as heat waves before.
As a group, our definition for a heat wave in Anchorage would be: any temperature reaching or exceeding 79 degrees Fahrenheit for three or more days consecutively. This is due to the fact that, according to the National Weather Forecast, Anchorage has never seen a temperature above 85 degrees Fahrenheit.
In June of 2015, Anchorage, as well as the rest of the state of Alaska, experienced a major heat wave. This had been a continuation of an usually warm winter, a record high temperature month of May, and a result that many in Alaska expected to last.
According to Market Watch, “Temperatures in Alaska’s biggest city hit 83 degrees on Monday and Tuesday, records for both calendar days and just two degrees shy of the June record set in 1969. Temperatures could again hit 80 on Wednesday. In Los Angeles, temperatures on Monday and Tuesday didn’t crack 80.”
Experts expected the heat wave to last until the end of the month, however, the damage had already been done. A dry winter led to many destructive wildfires. Even though it wasn’t a record number of wildfires, it was more destructive due to the amount of homes that were burned, this time around, in the process.
Because of all of the increased heat in the region, surface temperatures far above normal as well as earlier melting of winter ice has been more prevalent.
For the safety of Anchorage, a heat wave is particularly bad for the city. Not only are heat waves particularly devastating for citizens, as the table below will show different degrees of heat-related medical problems, but the decreased safety due to wild fires, animal shortages and being urban rather than rural contribute to dangers posed by high temperatures.
Sources are hyperlinked, however, here are more sources that we used: