Winter 2012 – 2013 Weather Outlook (November Update)
From Meteorologist Rich Apuzzo
The autumn of 2012 surprised many forecasters who thought that the warm pattern for most of the nation in the winter, spring and summer would continue. Persistence forecasting…simply going with the same pattern until something big happens…is fine in many situations, but when looking at seasonal forecasts it’s a bad idea. I have been producing long-range forecasts for years and experience has shown that one season doesn’t drive the next. A warm spring doesn’t mean a hot summer, and a hot summer doesn’t mean we’ll have a mild winter, nor does it suggest that winter will turn colder. The weather from one season to the next is not dependent on the previous season. It all depends on the weather patterns, and if they’re changing, your forecast must change.
Last summer I predicted a significant period of cooling for August, followed by a colder-than-normal autumn, and I based the forecasts on ocean temperature anomalies, solar output, drought patterns and tropical activity. Sure enough we had an August that started hot and then had two weeks of below normal temperatures in the Ohio Valley, before ending only slightly above normal in temperatures. September, October and November were all below normal, with November being the coldest (relative to normal).
The forecast was perfect, for both temperatures and rainfall, and in September I produced my first winter forecast using the same analysis. I looked at ocean temperature trends in the Atlantic and Pacific, with a focus on the equatorial Pacific where El Ninos and La Ninas develop. I also considered the weak solar cycle, the ongoing Plains drought and the generally quiet hurricane season (relative to U.S. impacts). My thinking since then hasn’t changed, so I’ll first cover the various ingredients to the forecast and then we’ll look at what I expect for December, January and February.
We’re in a period when the Pacific Ocean waters are colder than normal and likely to stay there for the next 10-15 years. At the same time the Atlantic Ocean is warmer than normal, but has been trending cooler with a reasonable expectation that it will also be colder than normal, probably by 2018 and possibly sooner. Looking at ocean temperatures alone favors weather patterns seen in the 1960s as well as the mid 1940s and the late 1980s to 1991. More on that in a moment.
Within the Pacific Ocean basin we have a region that, according to extensive research, significantly impacts our weather patterns, especially in the winter. It’s called the “ENSO region”, and ENSO stands for El Nino Southern Oscillation. The area is approximately between 5 degrees north and south latitude, extending along the equator from west of South America to almost Indonesia. When the water temperatures in this area are above normal for an extended period of time (at least 3 months) we call it an El Nino. When the waters are cooler than normal, it’s called La Nina. When the water temperatures are near the long-term average, the area is considered to be in a neutral phase which some call “La Nada”. I use that term as well since it fits with the other two.
As we head into winter, the equatorial waters are near normal, to slightly above normal, putting us in a neutral (La Nada) phase. Models are forecasting the waters to cool slightly, but remain within the neutral range through February. Adding that to the mix, we still have matching years in the 1940s, mid to late 1950s, 1960s and 2001.
The sun is in one of the weakest solar cycles in the last 200 years, and we have data back to the 1700s. Looking for other years with weaker solar cycles using the results above I found five solid matches and three years that are close. Using these years as a baseline (analogs) we can look forward. Here’s what happens when we look at the analog winter temperatures. The cool colors are areas with below normal temperatures while the warmer colors represent areas of above normal warmth.
I examined numerous years that fit our current global patterns and they all show the same trends…colder than normal weather for each of the winter months, with the heart of the cold in January. It’s normally our coldest winter month anyway, so a below normal January means that we’ll likely be extremely cold at times.
For precipitation, here’s what the analogs show.
It may look like a dry winter, but I need to make an important point here. Snow falls at an average ratio of 10 inches of snow to 1 inch of liquid, and in very cold air we can have ratios of 30 inches of snow to 1 inch of liquid…sometimes higher. If the winter is below normal in liquid precipitation, which is what the above maps show, it may be well above normal in snowfall since each month is expected to be quite cold.
Considering our analogs (above) and the current trends, here is what I expect. The winter will be colder than normal with a temperature range from 175 to 550 total degrees below normal (-1.9 to -6.0 degrees per day), and I expect 25 to 45 inches of snowfall in the Cincinnati area.
Because of an unusually cold and snowy start to the season in Canada (where some locations set records for November snowfall), the analogs may actually be too warm for the winter, but there’s another potential issue. Bitter cold in Canada contrasting with tropical warmth from the Gulf of Mexico can lead to extreme temperature battles, and that fuels large, windy winter storms with heavy rain, freezing rain and snow…and a much greater blizzard potential for our region. Keep an eye on southern Canada for blasts of bitter cold and watch the southern Plains for storm development that can tap into tropical moisture. This should be an interesting winter.
Keep Your Eyes on the Sky and Enjoy the Changing Weather!
Skyeye Weather LLC