This year alone has already had remarkable rainfall events around the world resulting in historic flooding. Just in the month of July, several European countries and central China suffered massive flooding. Last month in August, middle Tennessee had heavy rainfall and mammoth flooding.
And then so far this month, Hurricane Ida’s substantial rainfall generated considerable flooding in Louisiana, and the remnants of Ida dumped never seen before rain in New Jersey and New York, creating flash floods and urban flooding into places that have never previously had flooding. Each of these flooding events resulted in loss of life.
What is causing all these heavy rainfall events and subsequent extraordinary flooding, and could it happen here in the North Sound?
The World Attribution Initiative recently reviewed fresh peer-reviewed studies that analyzed how our warming world affected maximum 1-day and 2-day rainfall events in the wake of the July European floods. Studies involving the August and September flood events are underway.
The analysis confirmed that a warmer air mass holds more moisture, and the old adage of what goes up, must come back down, holds true. A climate of just a couple of degrees Fahrenheit (F) warmer holds about 3 to 19 percent more water in the atmosphere, resulting in a factor of 1.2 to 1.4 increase in rainfall amounts. If the climate is about 3 to 4 degrees F warmer, the amount of water the air can hold goes up another 3 to 19 percent more, and can produce another additional factor of 1.2 to 1.4 increase in rainfall amounts on top of just a two degree F warming. And that rainfall comes down in greater intensity.
The European substantial rainfall and massive flooding reflected these extreme statistics. It is expected similar study results will reflect the middle Tennessee and Ida ample rain and flood outcomes.
The 2010 decade was the warmest on record around the world. With a warmer atmosphere that can hold more water, the North Sound could potentially have record rainfall events producing significant flooding. The most likely cause for heavy rainfall in the North Sound come from what are called Atmospheric Rivers – a.k.a. – the Pineapple Express. These rivers of subtropical moisture can carry a lot of water well up into the atmosphere and dump a lot rain.
Most of the region’s big floods are the result of an Atmospheric River, hovering over the area for a few days and cause area rivers to surge well above flood stage. With today’s warmer air mass, the amount of available water and resulting rainfall could increase to levels not previously seen.
September is National Preparedness Month. With fall and winter just around the corner, now is the time to prepare for not only heavy rainfall producing flooding and possible landslides, but also strong damaging winds and lowland snow and ice. For helpful tips and checklists for your home, car, pets and more, go to ready.gov/ or takewinterbystorm.org .
In addition, learn what hazards can impact your home or business by visiting the Snohomish County Hazard Explorer, an interactive mapping tool of area natural hazards. To get alerts, Snohomish County Emergency Management offers a variety of resources that can best fit your needs. Skagit and Island County Emergency Management have similar resources. Having an all-hazards NOAA Weather Radio is one key resource for your home, car, business and more.
To help protect you, your family and business, take action today and you will be in a better position to endure whatever nature throws at us this winter season and beyond.