The Winter Forecast – Shovel ReadyOctober 27th, 2011 at 10:15 pm by Bill Steffen under Bill's Blog, Weather
This is going to be a winter, if you get my drift! The first map is the average North American winter conditions for La Nina. The second map is global sea surface temperatures, with the blue colors indicating areas where the water is colder than average, and yellow/orange where sea surface temperatures are warmer than average – click on the maps to enlarge) This is the second year in a row that we are heading into winter with La Nina (characterized by colder than average water temperatures along the Equator in the Pacific Ocean west of S. America). The La Nina this year is not as strong as the La Nina of one year ago. Here’s a map showing what last winter was like over the U.S. – only two of 48 states were colored warm. So, the first place to begin a winter forecast is with the general conditions favored by La Nina, shown in the map on the left. We see colder than average weather from Alaska down through the Pacific Northwest, Northern Rockies and Northern Plains…with warmer than average conditions on the whole from Arizona east across the southern U.S. to the Mid-Atlantic States (though Florida and the Southeast can get some good cold shots in early winter when we have La Nina). This provides a greater contrast than usual between warm to the south and cold to the north, implying some hefty storms this winter. The battle zone in between the warm air to the south and the cold air to the north will be the mean storm track for the winter…you can see the tendency for above average winter precipitation from the Pacific Northwest, across the Rockies (Denver’s already had a decent snowstorm this week), into the Ohio Valley. Areas on the northern edge of the avearge storm track will see above average snowfall, and that’s where the Southern Great Lakes is going to be this winter. (Click on “read on” to continue…).
If you look on the sea surface anomaly map on the right above, you can also see blue color (colder sea surface temperatures) in the shape of a backwards “C” across the northern Pacific, past Alaska and down the West Coast of the U.S. and northwest Mexico. That pattern is called a cold PDO (Pacific Decadal Oscillation). Look at this graph of the PDO over the past 110 years (side note…the PDO Graph is actually a better fit to U.S. temperatures over the past century than CO2. Note how temperatures tend to go down during extended periods with general cold PDOs like the 50s to 70s and then warmer with the warmer phase of the PDO, like during the 80s, 90s and 2000s). Note this article mentions the tendency for above average precipitation in the Great Lakes during winter when there is a cold PDO.
I’ve looked at so much more…what happened in years when we had both a La Nina and a large number of Atlantic basin hurricanes (we’re already up to the letter “R” this season), the water temperature of the Great Lakes (a little warmer than average) and Hudson Bay, the early season cold across Alaska and Northern Canada (the average temperature for the town of Alert has been -1.9°F for October), the growth of the Arctic icecap (about the same place as this time in 2009 and more ice than 2008 or 2007), the (rather anemic start to the) solar cycle. When all these factors came together, what happened during the following winter?
So, I’m forecasting 89″ of snow for Grand Rapids, 76″ for Kalamazoo, and 98″ for Holland and 100″ for Muskegon. Above normal snowfall is likely over most all of southern Great Lakes. We have a decent chance of a freezing rain event again this year (the ice storm along I-94 on 2/20/11 was described as the worst in that area in nearly a decade). We’ll see more than our fair share of challenging driving, as storms bring a lovely combination of fluffier lake-effect and the heavier snow that can come from low pressure centers. Storm systems that come up into Lower Michigan or go just north of us will bring a fun mix of precipitation (snow to freezing rain/sleet to rain and back to snow) I think the overall winter temperature is about 1 degree cooler than average for Grand Rapids and 1-2 degrees below average for Kalamazoo. I think this will be a longer winter. Last year, we didn’t get much snow before Dec. 1, and not much after 2/28. This year, I think snow starts around mid-November with snow lingering until at least early March. I think there is an above average chance of a White Christmas (80% for G.R. as opposed to the average 57%) and I think the period from mid-November to early January will, on the whole be colder than average in West Michigan.
This will be a good year to take a southern vacation…after a cool December, temperatures should moderate in Florida during the latter half of winter. The Pacific Northwest looks cool and wet (could Seattle get snow this winter??) with lots of snow in the Cascades up into southern Alaska and east across the Rockies. I also think the coming spring will bring an above average number of tornadoes. La Ninas usually have about 20% more tornadoes than average, and the upper atmosphere is ever so slightly cooler relative to the ground when you look at NASA upper atmosphere temperatures. The contrast between cold to the north and warm to the south means an above average number of strong to violent tornadoes (which until 2010 had been trending down in the U.S. since the 1970s). Hopefully, they won’t hit populated cities as much as last year (Joplin, Birmingham, Tuscaloosa, Springfield MA, Minneapolis).
I’ll continue to add more as we head into the winter. By the way, here’s the Old Farmer’s Almanac Forecast (I don’t agree with their cool and snowy winter in the south or the dry winter in the Ohio Valley/southern Great Lakes). The 90-day forecast from the Climate Prediction Center looks pretty good to me. Here’s the National Weather Service Winter Forecast and this also looks pretty good. Again, note the greater contrast of temperatures (colder than average to the north and warmer than average to the south). That means some big storm systems this winter and spring. I’ll link to Bill Marino’s forecast when that comes out at the GRR NWS site. He’s going 85″ for the winter. Craig James has a forecast of 90″ – so…either brilliant minds think alike, or we’re all mediocre-ologists.
Don’t be afraid to get that season ski pass or to line up a snowplow service for the season. Save a couple extra dollars for the heating bills this winter. Remember to observe odd/even parking if that applies, make sure your pets and animals are comfy and keep checking here at Bill’s Blog and on WOOD-TV for the latest winter weather updates.