Looking ahead in the current NWS Lower Mississippi River summary, many U.S. rivers will be falling lower by the end of the month, even with the current rain forecast. As far as the snow, it becomes more of a factor in the spring when the melt reaches the rivers. It is important to note the water content of the snow that falls, i.e. powdery versus heavy wet snow. According to Accuweather, powdery snow contains less water; on average, 5 inches of dry snow will melt to only 0.5 inch of water. Wet snow, on the other hand, can equal up to an inch of water for every 5 inches of snow.
Currently, according to the Jan. 25 U.S. snow depth map released by the NOAA Office of Water Prediction (OWP) National Water Center, seasonal accumulation of snow cover is the lowest for this date in nearly 15 years at this time (https://www.nohrsc.noaa.gov/…).
The latest Midwestern Regional Climate Center Accumulated Winter Season Index (AWSSI) map shows that many of the states along the U.S. river system have had mild winter conditions. Of course, it’s only January, and things could change. But the lack of snowfall up to this point along the river system is noticeable (https://mrcc.illinois.edu/…).
The low water conditions on the Mississippi River have persisted since fall 2020. Going back to early October 2020, the Mississippi River level at St. Louis was nearing 1 foot above zero gauge, and the Mississippi River in Memphis, Tennessee, was 2.5 feet below the low stage of 5 feet. Currently, the level at St. Louis is expected to reach the 1-foot stage next week, and Memphis is currently at 0.7 below zero gauge.
While barges have been able to move smoothly the past few weeks, if river levels continue to fall, that could create slowdowns and/or stoppages if areas in the Lower Mississippi River need to be dredged due to shoaling, or worse, if barges are grounded in extreme low-water spots.
NWS Hydrograph Mississippi River St. Louis, Missouri: https://water.weather.gov/…
NWS Hydrograph Mississippi River at Memphis, Tennessee:
NWS Lower Mississippi River summary:
Mary Kennedy can be reached at firstname.lastname@example.org
Follow her on Twitter @MaryCKenn
(c) Copyright 2021 DTN, LLC. All rights reserved.