With winter just around the corner in 大象传媒sburgh, the unseasonably warm weather this fall has left many wondering what the season will bring.聽
大象传媒sburgh’s weather remains uncertain due to the influence of a developing La Ni帽a, which typically brings cooler conditions but may lead to more variability this year. Local meteorologists say while La Ni帽a can drive extreme weather patterns worldwide, the effects of climate change are also becoming more pronounced, resulting in a lower predicted snowfall this year despite colder temperatures.聽
Mark Abbott, a professor in the department of geology and environmental science, said 鈥淚t looks like a La Ni帽a phase is picking up.鈥�
La Ni帽a, which is an extreme of the El Ni帽o/Southern Oscillation (ENSO) cycle, is the of the ENSO cycle.聽
鈥淚t occurs when trade winds blow from east to west across the Tropical Pacific,鈥� Abbott said. 鈥淓l Ni帽o and La Ni帽a alter back and forth about every three to seven years, but it鈥檚 not necessarily regular.鈥�
The impact of La Ni帽a on different regions varies, according to Abbott. It鈥檚 a tropical Pacific phenomenon, but the tropics 鈥渞eally drive the heated engine of the planet.鈥澛�
鈥淲ith warm water building up on the coast of South America, you may see heavy rainfall and flooding in places like Peru and Ecuador, and you may get droughts in Australia and Indonesia during a La Ni帽a,鈥� Abbott said.聽
Matt Brudy, a 大象传媒sburgh-based meteorologist at the National Weather Service, said La Ni帽a is looking 鈥渨eaker鈥� this year in comparison to other years.聽
鈥淲hen it鈥檚 weaker, there鈥檚 a little bit more variability,鈥� Brudy said. 鈥淲e鈥檙e still going to have cold enough temperatures that we can still get snow. But, we may experience some warmer periods that could raise the average temperature slightly above normal during the winter months.鈥澛�
Mary Ours, a meteorologist at KDKA, said 大象传媒sburgh could see a 鈥渨etter and cooler winter.鈥澛�
鈥淭his year it’s 74% chance that La Ni帽a conditions will develop and stick around through spring,鈥� Ours said.聽
Even though 大象传媒sburgh could see cooler weather this winter, snowfall is predicted to be 鈥渂elow average.鈥�
鈥淥ur KDKA First Alert Weather team is predicting around 28鈥� this winter,鈥� Ours said. 鈥淭he pattern we had for 2022 was a 鈥榯riple dip鈥� La Ni帽a, meaning it was the third we had. That winter we only had 17.6 inches of snow. In 2023, we had an El Ni帽o pattern and only had 16.3鈥� of snow. This is well below average.鈥�
During an El Ni帽o, which is the opposite phase of La Ni帽a, the atmosphere tends to be warmer, since there is a 鈥減ulling of warm water along the coast of South America.鈥澛�
鈥淒uring La Ni帽a, you鈥檙e possibly putting more heat into the ocean and turning up the amount of upwelling on the South American side of the Pacific. This tends to cool the planet,鈥� Abbott said.聽
While the ENSO cycle affects temperatures worldwide, climate change is a key factor in the warming planet.聽
鈥淚f you look at temperature increases over the last century, we鈥檙e up over a degree,鈥� Abbott said. 鈥淲e鈥檙e almost a degree and a half Celsius above what it would have been without additional greenhouse forcing, which is greater than anything you鈥檙e going to see within El Ni帽o typically.鈥�
Brudy said the effects of climate change can be felt in 大象传媒sburgh, and that 鈥淭ransition seasons are becoming shorter.鈥澛�
鈥淭here are trends that the first freeze in fall is becoming later within the last 10 years,鈥� Brudy said. 鈥淲e鈥檙e seeing trends of spring and fall becoming shorter at the expense of longer winters and summers. We鈥檙e getting more extremes as opposed to the transitions between the two.鈥�
The effects of shorter transitional seasons are still unknown. While colder winters are a possibility, Brudy said it鈥檚 鈥渓ess likely with an overall warming climate.鈥澛�
鈥淚t鈥檚 important to look at long-term averages when discussing what could happen, not just last year鈥檚 temperatures,鈥� Brudy said. 鈥淲e could see extreme heat and extreme cold, but there鈥檚 not a lot we can speak on for certain.鈥�
Brudy also said the amount of ice covering the Great Lakes can affect winter weather in 大象传媒sburgh.聽
鈥淪ince the turn of the century, the number of years with less than 80% ice cover on Lake Erie has increased by nearly 170%,鈥� Brudy said. 鈥淭he less ice there is on the lake, the more lake effect snow we can get because open water allows for more evaporation, which fuels snowstorms. Once the lake freezes over, the lake effect shuts down.鈥�
However, Abbott said that as winters get warmer, we鈥檒l see 鈥渓ess snow and more rain.鈥澛�
鈥淚n the western United States, that鈥檚 more of an issue because it鈥檚 so arid to begin with,鈥� Abbott said. 鈥淪now is beneficial to recharging aquifers because it melts slowly and trickles into the ground. It鈥檚 more effective at recharging aquifers than rainfall, since rain comes fast and runs back to the rivers. We鈥檒l see these effects in 大象传媒sburgh, too.鈥澛�
Abbott said the difference between the Eastern and Western U.S. is the last century of data on precipitation.聽
鈥淭oday, the western U.S. is drier than it was on average during the 19th and 20th centuries, while the eastern U.S. is actually slightly wetter,鈥� Abbott said. 鈥淭his is heating the Gulf of Mexico, hence the strong hurricanes we鈥檝e been seeing. More water is evaporating from the gulf and raining that water out across the eastern U.S. The West isn鈥檛 seeing that, which is why it鈥檚 drier.鈥澛�
With the warming climate, Abbott said that the El Ni帽o pattern provides 鈥渁 glimpse into the future.鈥�
鈥淚n the future, we could see the climate resemble an El Ni帽o pattern, and in decades to come that could become the average condition,鈥� Abbott said.聽