This tends to focus storminess across the Ohio Valley and Great Lakes, leaving the Carolinas high and dry with warmer than normal temperatures.īelow average water temperatures developed across the tropical east Pacific ocean during the summer of 2020, and La Niña officially began in September. The position of the polar jet stream also lifts farther north during La Niña. Typical winter jet stream with temperature & precipitation anomalies during La Niñaĭuring La Niña, cool water in the tropical Pacific causes fewer thunderstorms to form there, leading to a weaker subtropical jet stream that brings less moisture and less rainfall to the southern United States during the winter. There is no definite pattern to how often El Niños or La Niñas occur, but a complete cycle usually lasts 2 to 5 years. The warm phase of this cycle is called El Niño, and the cold phase is called La Niña. The tropical eastern Pacific Ocean displays a natural cycle in water temperatures which is part of the El Niño Southern Oscillation (ENSO). This lowers (but doesn't eliminate) the chances of very cold temperatures. The warm phase of the AMO we're in began around 1996 and will continue this winter. This cool phase is associated with more frequent cold air outbreaks along the East Coast. This is followed by an approximately 30 year long cool period when North Atlantic Ocean water temperatures cool by approximately 0.5 degrees Celsius. This warm phase of the AMO is associated with fewer outbreaks of arctic cold along the U.S. For approximately 30 years water temperatures averaged across the North Atlantic Ocean are warm. North Atlantic Ocean water temperatures naturally warm and cool in a 60-to-70 year cycle called the Atlantic Multidecadal Oscillation, or AMO. Graph of North Atlantic Ocean temperature anomalies showing the pattern we call the Atlantic Multidecadal Oscillation (AMO). Fortunately there are other factors that are correlated with longer term trends in temperature and precipitation during the winter. There are many factors that influence our wintertime weather across North and South Carolina. The movement of highs, lows, cold fronts, and warm fronts control our day-to-day weather but become impossible to forecast with any accuracy more than eight or nine days in advance. Higher chances of below-normal precipitation are forecast across the Carolinas. Precipitation outlook for this coming winter. Slightly higher chances of above-normal temperatures are forecast across the Carolinas. Temperature outlook for this coming winter. Outlooks from the NWS Climate Prediction Center indicate above-normal temperatures should continue through the upcoming winter season (December 2020 through February 2021) along with an increased likelihood for drier than normal weather. So far 2020 has been one of the warmest years in recorded history across the eastern Carolinas with temperatures running 2 to 3 degrees above normal.
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