National Weather Service United States Department of Commerce

Accumulating Snow For Many Tue - Be Ready For Wintry Travel

A very early season winter storm will bring a few inches of snow to the region Tuesday into Tuesday night. While the higher accumulations will hold to grassy and other colder surfaces, many roads will accrue snow - resulting in slippery travel. Be ready to exercise your winter driving skills where the snow falls. Read More >

NOAA's CPC Winter 2020-21 Outlook
for the Upper Mississippi River Valley


Released: October 15, 2020
Next Update: November 19, 2020

 

Bottom Line for the Local Area...


NOAA's Climate Prediction Center (CPC) forecast for the upcoming winter months of December-February:

Temperatures: Equal chances of warmer-than-normal, near-normal, and colder-than-normal. 

  • While this La Niña is expected to be moderate to strong, these winters can be highly variable.  Since 1950, there have been 4 moderate (1955-56, 1970-71, 1984-85, and 2010-11) La NiñasAll of these were among the coldest third of winters. There have been 7 strong (1949-50, 1973-74, 1975-76, 1988-89, 1998-99, 1999-2000, and 2007-08) La Niñas since 1950Six of these 7 La Niñas were either among the warmest third (3 La Niñas) of winters or had near-normal temperatures (3 La Niñas). 
  • In addition, there has been no temperature trend for winters during the past 15 years.  There has been nearly an even split between warmer-than-normal and colder-than-normal.

Precipitation: Wetter-than-normal is slightly favored.  This does not necessarily imply that this winter will end up being snowier-than-normal. 

  • This was based more on climate trends than La Niña.  During the past decade, Rochester MN has had 9 wetter-than-normal winters, and La Crosse WI has had 7 wetter-than-normal winters.    
  • Like temperatures, moderate and strong La Niñas can be highly variable with their winter precipitation totals.  The 4 moderate La Niñas were either among the wettest third (3 La Niñas) or driest third (1 La Niña).  During the 7 strong La Niñas, 4 had near-normal precipitation, 2 were among the driest third, and 1 was among the wettest third. 

Background...


A moderate to strong La Niña is favored to develop during the remainder of the Northern Hemisphere autumn and peak out in either December or January. Due to this, the CPC winter temperature and precipitation outlooks are consistent with typical La Niña impacts. 

The last time that there was a La Niña winter was 2017-18 (weak).

Besides La Niña, this winter will also be affected by:

  • Arctic Oscillation (AO) and North Atlantic Oscillation (NAO) - These oscillations can influence the number of Arctic air masses that penetrate into the Southern United States and nor'easters on the East Coast.
  • Eastern Pacific Oscillation (EPO) - This can affect the location of where the cold air masses will be located in the northern United States
  • Madden-Julian Oscillation (MJO) - This can affect both temperatures and precipitation in the weekly time scale.