Persistent mild weather as El Nino takes charge

The large scale pattern that is typically associated with El Nino has arrived. The cold patterns that have been dominating our weather over much of the past two years are gone and may not return for several months. El Nino refers to a large area of warmer than normal ocean temperatures along the equator in the central and eastern Pacific Ocean. See the following link for more information:

http://www.elnino.noaa.gov/

The area of warmer than normal water is large enough that it affects the global atmospheric circulation. Thus, El Nino can have a strong impact on winter temperatures in Minnesota, more often making them significantly warmer than average.

Out of 18 El Nino winters since 1950, winter (Dec-Jan-Feb) temperatures in Grand Rapids have been above average 11 times and below average 7 times. The average Grand Rapids winter temperature for all years since 1950 is 11.2 degrees F. During El Nino events, the mean winter temperature has been 13.1 degrees F, nearly 2 degrees above average. The warmest of the El Nino events was in 1997-1998 when Grand Rapids winter temperature averaged over 22 degrees F, which is also Grand Rapids' warmest winter on record. This winter will see the strongest El Nino since the 1997-98 event. It is interesting to note that during the 1960s and 1970s, most El Nino winters were below average in temperature, so we're not guaranteed a warm winter, but since 1980, all of them have been warm, so my bet will be on warm temperatures (that's the global trend anyway).

As far as snow is concerned, snowfall tends to be below average: 47.9 inches during El Nino seasons versus 59.9 for all others (since 1950). 56.3" has been the average snowfall for all winters (including El Nino) since 1950. Out of 18 El Nino winters, 15 had less than this average. However, there have been exceptions. The winters of 1966, 1969, and 1970 all had over 70 inches of snow. The primary reason for reduced snowfall is the split flow in the jet stream, which keeps the cold air to the north of Minnesota and the storm track mostly to the south.

For the deer hunting rifle opener, we'll have mild weather with temperature in the 50s. If we get more sun than forecast, the airmass will be warm enough for temperatures in the 60s, but 50s looks more likely at this point. Sunday will see warm, sunnier weather with temperatures in the 50s. Thereafter, the weather should be mostly dry and mild through about November 15, and the mild pattern will likely persist through at least November 20 and perhaps the rest of the winter.