It is a fair bet that we would get near universal agreement that the weekend of November 15-16 was incredibly nice, even the slightly cooler Sunday that followed a truly remarkable Saturday. Both Milwaukee and Madison set all-time record high temperatures for November 15 at 69 and 68 degrees Fahrenheit, respectively.
Apart from the fact that each city recorded highs that were at least 20 degrees lower the very next day (46 for Milwaukee and 48 for Madison), the weekend was also noteworthy for another meteorological reason: At least for Madison, November 15 is the date on which the probability of precipitation falling as snow first reaches 50%. This means that, from here on out, if precipitation is in the forecast, there is at least an even chance that it will fall as snow. Only 10 days later comes the average date of our first 1-inch snowfall.
So if the thought occurred to you as you enjoyed an almost summery day on November 15 that we were way over our meteorological skis, you were exactly right.
Currently the tropical Pacific Ocean is undergoing a weak La Nina event, which means the ocean temperatures in the central tropical Pacific are slightly cooler than normal. Such an anomaly does not have a very consistent impact on the winter weather over our region, unlike its opposite, the El Nino.
In fact, the latest outlook for this winter (December, January and February), released by the Climate Diagnostics Center on October 16, suggests that we have “equal chances” of being warmer or colder than normal in southern Wisconsin. The same forecast suggests “leaning above” for our precipitation outlook for the winter.
Of course, neither of these outlooks precludes us being visited by either a big snow or a frigid cold air outbreak during our coming winter. However, it may be that the winter will feature only limited appearances by such events.
Steve Ackerman and Jonathan Martin, professors in the UW-Madison department of atmospheric and oceanic sciences, are guests on WHA radio (970 AM) at noon the last Monday of each month. Send them your questions at stevea@ssec.wisc.edu or jemarti1@wisc.edu.
