Will El Niño Drop Great Lakes Water Levels?
A Warmer Winter Ahead?
El Nino is expected to develop in the next two months and continue through winter. The stronger the El Nino is, the higher the potential impact on Michigan’s winter.
When the ocean temperature on surface waters climb above normal temperatures, an El Nino condition exists. The ocean temperatures along the Equator from South America to the western Pacific look to support the El Nino determination. The warmer water affects air circulation and a domino effect on worldwide weather patterns results.
Michigan and the Great Lakes have increased chances of warmer and drier than average conditions in the winter during an El Nino. The chances of the milder winter increase as the water temperature increases.
Great Lakes Water Levels Look to Drop for Winter 2018-2019
The Army Corp of Engineers in Detroit reported that the summer of 2018 was rather hot across the Great Lakes basin. Many places throughout the region experienced a top 10 warmest summer based on average temperature over the 3 month time period. This edition of the Water Level Outlook incorporates the projection of water levels if Net Basin Supply (NBS) values are similar to those seen during the years when a hot summer was experienced in the Great Lakes basin followed by either a warm or cold October through December. The purple plume represents the range of water levels given the NBS scenarios of the hottest 14 summers occurred. The blue and red lines represent the NBS scenarios if a hot summer was followed by either a cold or warm October to December, respectively. The most recent coordinated 6-month forecast is also shown for comparison.
Last El Nino was 2016
The Detroit Offices of the Army Corps of Engineers are noted in 2016 that regional climatic forecasts were influenced by strong El Niño conditions. These conditions were anticipated to continue throughout the winter and into the spring of 2016. Climate forecasts show warm winter temperatures accompanied by drier conditions, especially after November. The outlook graphics show monthly mean water levels that could significantly drop over the next year. This potential mirrors the current water levels and the conditions that were experienced during the two strongest El Niño periods on record 1982-83 and 1997-98.
Could Lake Levels Drop Again?
The 12-month water level outlook was produced by simulating the routing of an ensemble of 12-month sequences of Net Basin Supply (NBS, which represents the combined impacts of precipitation over the lake, runoff to the lake, and evaporation from the lake). The ensemble consists of 12-month NBS sequences taken directly from the coordinated record of residual net basin supply. The grey shaded area depicts the range of possible water level outcomes given current existing conditions and the range of NBS that has previously been observed. The red and blue lines represent projected water levels simulated using NBS sequences that correspond with the two strongest El Niño periods on record (blue: 1982-83 and red: 1997-98). The most recent coordinated 6-month forecast is also shown for comparison.
2013-14 was the lowest recorded water levels in lakes Michigan-Huron since 1963.
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