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Great Lakes Water Level Outlook- April 2020 Edition - Updated May 2020

Outlook Summary:

This product is not an official forecast of Great Lakes water levels. Rather, this product is meant to illustrate outcomes that would occur under historical weather and water supply condition, with scenarios chosen based on similarities to recent conditions. For the official forecast, please see our Monthly Bulletin of Great Lakes Water Levels.

 

Monthly mean water levels continue to be near or above record high levels across the Great Lakes. These near record high water levels have been a result of persistent wet conditions that have existed over the past several months to years. Water levels follow a seasonal cycle where water levels rise in the spring due to increased precipitation and enhanced runoff from snowmelt. In the fall, the lakes generally decline due to an increase in evaporation as temperatures decline and cold air moves over the relatively warm lake waters. We refer to the combined effect of precipitation over the lake, evaporation from the lake, and runoff to the lake as Net Basin Supply (NBS). This past winter the Great Lakes basin experienced low ice cover with the maximum total ice cover peaking at 19.5%. Over the past decade, there have been two other winters, 2012 and 2017, which also had ice cover below  20%. A common question is how a warmer winter marked by low ice cover will impact water levels in the future spring, summer, and fall? This edition of the Water Level Outlook incorporates the projection of water levels if the NBS over the next 12 months is similar to what occurred in 2012-13 or 2017-18. The purple line represents the 2012-13 scenario, while the blue line represents the 2017-18 scenario. Comparing these two year following a warm winter with low ice cover highlights the wide range of possible conditions that could follow. The most recent coordinated 6-month forecast is also shown for comparison.



Click on the individual graphics to view a larger, printer-friendly image (pdf).




 



 
 
* For the official 6-month forecast of all lakes, including Lake Ontario, see the Monthly Bulletin of Great Lakes Water Levels.
 

 

Click here to obtain the full Great Lakes Water Level Outlook document (pdf)

Great Lakes Water Level Outlook Data

 

To view the water level outlook data in tabular format, click on the links below.

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Lake Superior

Monthly Mean Water Level (meters IGLD)

  May-20 Jun-20 Jul-20 Aug-20 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Mar-21 Apr-21
2012-13 183.67 183.79 183.84 183.80 183.69 183.61 183.55 183.47 183.40 183.34 183.30 183.32
2017-18 183.68 183.78 183.85 183.89 183.92 183.92 183.85 183.78 183.72 183.65 183.59 183.54
Ensemble Median 183.67 183.75 183.81 183.83 183.82 183.78 183.73 183.65 183.56 183.50 183.46 183.50
Long Term Average 183.37 183.45 183.51 183.54 183.54 183.52 183.47 183.41 183.33 183.27 183.24 183.26
Long Term Maximum 183.77 183.84 183.86 183.86 183.86 183.91 183.89 183.81 183.70 183.63 183.61 183.68
Long Term Minimum 182.76 182.85 182.96 183.01 183.02 183.10 183.01 182.92 182.83 182.76 182.74 182.72

 

Lake Michigan-Huron

Monthly Mean Water Level (meters IGLD)

 

  May-20 Jun-20 Jul-20 Aug-20 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Mar-21 Apr-21
2012-13 177.34 177.34 177.31 177.22 177.08 176.95 176.86 176.79 176.76 176.76 176.76 176.87
2017-18 177.39 177.50 177.55 177.51 177.44 177.40 177.37 177.29 177.25 177.26 177.26 177.28
Ensemble Median 177.37 177.42 177.44 177.41 177.35 177.26 177.18 177.12 177.07 177.03 177.04 177.08
Long Term Average 176.49 176.56 176.59 176.57 176.52 176.45 176.39 176.35 176.30 176.29 176.31 176.39
Long Term Maximum 177.28 177.33 177.39 177.39 177.38 177.50 177.38 177.26 177.18 177.11 177.12 177.23
Long Term Minimum 175.74 175.76 175.78 175.77 175.76 175.70 175.65 175.61 175.57 175.59 175.58 175.61

 

Lake St. Clair

Monthly Mean Water Level (meters IGLD)

 

  May-20 Jun-20 Jul-20 Aug-20 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Mar-21 Apr-21
2012-13 175.92 175.88 175.81 175.71 175.60 175.51 175.45 175.40 175.43 175.46 175.48 175.59
2017-18 175.96 176.04 175.99 175.94 175.85 175.79 175.82 175.79 175.69 175.79 175.86 175.92
Ensemble Median 175.92 175.93 175.90 175.84 175.76 175.68 175.62 175.60 175.56 175.56 175.60 175.70
Long Term Average 175.14 175.19 175.21 175.17 175.10 175.01 174.93 174.93 174.85 174.80 174.92 175.06
Long Term Maximum 175.89 175.99 176.04 175.96 175.86 175.96 175.82 175.80 175.80 175.80 175.80 175.82
Long Term Minimum 174.42 174.45 174.50 174.41 174.34 174.27 174.18 174.24 173.88 173.89 174.05 174.32

 

Lake Erie

Monthly Mean Water Level (meters IGLD)

 

  May-20 Jun-20 Jul-20 Aug-20 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Mar-21 Apr-21
2012-13 175.03 174.95 174.85 174.76 174.66 174.59 174.54 174.51 174.51 174.56 174.61 174.71
2017-18 175.14 175.18 175.14 175.09 174.95 174.80 174.80 174.82 174.77 174.85 174.93 175.00
Ensemble Median 175.05 175.04 174.99 174.90 174.79 174.68 174.61 174.61 174.63 174.63 174.70 174.81
Long Term Average 174.32 174.35 174.34 174.27 174.18 174.08 174.01 174.01 174.01 174.00 174.09 174.24
Long Term Maximum 175.05 175.14 175.13 175.02 174.87 174.94 174.85 174.89 174.86 174.78 174.88 174.98
Long Term Minimum 173.44 173.45 173.45 173.43 173.38 173.30 173.20 173.19 173.21 173.18 173.20 173.38

 

Lake Superior

Monthly Mean Water Level (ft IGLD)

  May-20 Jun-20 Jul-20 Aug-20 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Mar-21 Apr-21
2012-13 602.60 602.97 603.15 603.02 602.67 602.41 602.20 601.94 601.72 601.52 601.39 601.46
2017-18 602.62 602.97 603.18 603.33 603.42 603.41 603.20 602.96 602.77 602.54 602.34 602.15
Ensemble Median 602.59 602.85 603.04 603.11 603.09 602.96 602.79 602.53 602.23 602.02 601.91 602.03
Long Term Average 601.61 601.87 602.07 602.17 602.17 602.10 601.94 601.74 601.48 601.28 601.18 601.25
Long Term Maximum 602.92 603.15 603.22 603.22 603.22 603.38 603.31 603.05 602.69 602.46 602.40 602.62
Long Term Minimum 599.61 599.90 600.26 600.43 600.46 600.72 600.43 600.13 599.84 599.61 599.54 599.48

 

Lake Michigan-Huron

Monthly Mean Water Level (ft IGLD)

 

  May-20 Jun-20 Jul-20 Aug-20 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Mar-21 Apr-21
2012-13 581.82 581.82 581.73 581.43 580.96 580.55 580.25 580.03 579.93 579.91 579.92 580.27
2017-18 582.00 582.33 582.51 582.38 582.14 582.02 581.91 581.67 581.52 581.56 581.56 581.64
Ensemble Median 581.92 582.09 582.15 582.05 581.85 581.56 581.28 581.11 580.95 580.82 580.83 580.98
Long Term Average 579.04 579.27 579.36 579.30 579.13 578.90 578.71 578.58 578.41 578.38 578.44 578.71
Long Term Maximum 581.63 581.79 581.99 581.99 581.96 582.35 581.96 581.56 581.30 581.07 581.10 581.46
Long Term Minimum 576.57 576.64 576.71 576.67 576.64 576.44 576.28 576.15 576.02 576.08 576.05 576.15

 

Lake St. Clair

Monthly Mean Water Level (ft IGLD)

 

  May-20 Jun-20 Jul-20 Aug-20 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Mar-21 Apr-21
2012-13 577.16 577.03 576.80 576.48 576.12 575.81 575.63 575.46 575.55 575.64 575.72 576.08
2017-18 577.29 577.55 577.41 577.22 576.92 576.75 576.85 576.75 576.42 576.74 576.97 577.17
Ensemble Median 577.16 577.19 577.12 576.91 576.63 576.38 576.19 576.11 575.98 575.99 576.13 576.43
Long Term Average 574.61 574.77 574.84 574.70 574.48 574.18 573.92 573.92 573.65 573.49 573.88 574.34
Long Term Maximum 577.07 577.40 577.56 577.30 576.97 577.30 576.84 576.77 576.77 576.77 576.77 576.84
Long Term Minimum 572.24 572.34 572.51 572.21 571.98 571.75 571.46 571.65 570.47 570.51 571.03 571.92

 

Lake Erie

Monthly Mean Water Level (ft IGLD)

 

  May-20 Jun-20 Jul-20 Aug-20 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Mar-21 Apr-21
2012-13 574.24 573.99 573.66 573.35 573.03 572.80 572.62 572.54 572.54 572.70 572.87 573.18
2017-18 574.61 574.75 574.62 574.43 573.99 573.50 573.49 573.54 573.41 573.64 573.93 574.13
Ensemble Median 574.33 574.28 574.10 573.82 573.47 573.11 572.88 572.87 572.94 572.94 573.17 573.53
Long Term Average 571.92 572.01 571.98 571.75 571.46 571.13 570.90 570.90 570.90 570.87 571.16 571.65
Long Term Maximum 574.31 574.61 574.57 574.21 573.72 573.95 573.65 573.79 573.69 573.43 573.75 574.08
Long Term Minimum 569.03 569.06 569.06 569.00 568.83 568.57 568.24 568.21 568.27 568.18 568.24 568.83

 

Detroit District Disclaimer

NOTICE: All data contained herein is preliminary in nature and therefore subject to change. The data is for general information purposes ONLY and SHALL NOT be used in technical applications such as, but not limited to, studies or designs. All critical data should be obtained from and verified by the United States Army Corps of Engineers, Detroit District, Engineering and Technical Services, Great Lakes Hydraulics and Hydrology Office, 477 Michigan Ave., Detroit, MI 48226. The United States of America assumes no liability for the completeness or accuracy of the data contained herein and any use of such data inconsistent with this disclaimer shall be solely at the risk of the user.