Local Data Suggests
Temperatures: Normal to Above
Snowfall and Rainfall: Normal to Above depending on location
Using the expected dominant storm tracks for the upcoming winter, it is likely much of the region will experience normal to above normal precipitation with above normal snowfall /5.0"+/ around Detroit's northern and western suburbs north into the Flint and Saginaw Valley; to around normal /within 5.0"/ over the far Southeast corner of Lower Michigan (south of Detroit). Mixed precipitation events seem to be a higher than normal risk.
Broad Scale Discussion
1 - La Nina
The strength of the previous La Nina 2010-11 is quite evident by the below normal SST's dipping to -2.0C as opposed this winter's expected ~ -.7C to -1.1C
October 2016 Average SST's
Multivariate ENSO Index 1950 - early 2016 shows up to the strong El Nino of the past year and note the strong La Nina during the Winter of 2010-11.
The Southern Oscillation Index /SOI/ below shows well the recent negative corresponding values in conjunction to our recent strong El Nino. Remember; an above normal SST is reflective of a negative SOI.
Latest Modeling Projections of the expected weak La Nina to Neutral conditions
Corresponding Analogue Years by SOI values (positive = La Nina)
(only numerical values for the first two analogues available)
1878 4 -8.2 1
1878 5 2.5 4
1878 6 -3.2 5
1878 7 14.8 4
1878 8 12.4 2
1878 9 17.5 2
1878 10 11.7 2
1878 11 14.4 2
1878 12 16.6 2
1879 1 12.1 2
1879 2 14.1 2
1879 3 10.8 2
1879 4 10.9 2
Available SOI Graphs below from analogues years reflect Neutral to ModerateSOI 1889-901889 4 -0.8 41889 5 -1.2 51889 6 18.4 41889 7 1.4 31889 8 2.1 51889 9 11.1 41889 10 4.7 21889 11 22.0 41889 12 20.7 21890 1 20.3 21890 2 10.6 21890 3 11.8 21890 4 5.7 2
La Ninas after strong El Ninos.
Latest SOI data through October shows a Neutral to weak La Nina state
2-Pacific Decadal Oscillation /PDO/ and associated subset EPO
There were only two winters in this winter's outlook research that contained a warm state PDO while the La Nina developed and prevailed; the Winter of 1878-79 and 1983-84. The 1878-79 La Nina winter was fairly weak while the 1983-84 La Nina winter was a bit more developed. Curiously, those two winters were our coldest in this season's analogues.
3-North Atlantic/Arctic Oscillation /NAO & AO/
Projections of this winter's NAO/AO are variable. One scientist who bases NAO/AO trend expectations and subsequent winter temperatures, Judah Cohen , strongly bases the winter temperature projection on early snowfall across Eurasia along with sea ice coverage in the early Autumn. His research has shown that these variables affect the NAO/AO development and positioning.. At this time with higher than normal snowfall coverage in that area and weaker ice formation in the Arctic this fall, projections are for a colder winter for almost all of the eastern U.S (excepting New England). Mr. Cohen has a nice update here every week or so on current and expected trends.
Solar cycle actual effects on short term weather and longer term climate variability remain a controversial subject. I've read several articles which support or are against their shorter term winter relevancy. Some theorize that both natural solar cycles and man's influence affect our climate. I am in favor of the solar cycle being somewhat relevant and sometimes giving the present winter cycle a "little kick" in regard to hemispheric wind flow patterns and resulting temperatures. Studies out of Europe for example, do in fact make the connection to wintertime effects.
Comparing solar cycles of the past analogue winters to the present as a possible influence only and not a major contributor. While the solar cycle was in various modes, the tendency is for these La Nina's to Neutral winters to occur during the mid to lower part of the cycle or during an overall, weaker cycle (like the one we have entered, below).
The closest previous solar cycles (strength and positioning) during the analogue winters to this upcoming winter occurred in; the winter's of 1897-98, 1973-74, 2007-08 (averaged normal temperatures). Besides those winters, the winters that also occurred during the decline but near or at the lull of the solar cycle (like next winter, 2017-18 for example) are; 1878-79, 1889-90, 1964-65 and 2010-11. Therefore, we have seven (out of 11) analogue winters in the study that were near this winter's expected solar cycle positioning. The winter of 1998-99 was near the same positioning but was during the incline.
Winter 2016-17 Analogues
(click on table to enlarge)
Analogue Research and Results
As stated above, the analogue years were quite variable but with a tendency toward below normal temperatures. Remember, looking at Detroit alone, you run into the influenced heat island normals, which then would tend to skew the averages below normal slightly, since they are warmer (than the 100 year) - get it? Anyway, all three cities suggest a normal winter when the variances are averaged. Looking at the individual winters, there still remains a preference for a below normal winter. Winter's were most active mid to late winter, with the highest snowfalls mid winter. Looking at December's alone; suggests that the winters (notable snows) started generally mid to late month, somewhat later than average. Back to the entire winter; the second preference was for a normal winter and the least was for an above normal. This certainly fits La Nina winters but we are not dealing with just a La Nina winter. The analogues represent quite a range Neutral to moderate La Ninas and still I was only able to find 11 that match the past strong El Nino melding into a Neutral to moderate La Nina by the next winter season.
Even with the dominant normal to below normal winters; there were a decent showing of above normal winters, enough to pull the averages back to near normal. As mentioned above, the coldest winters were found when the rare warm PDO existed above the cool La Nina, as in this present year. Studies have found this tends to dampen the effects of the La Nina.
The split in the temperature pattern (above normal Southeast to below North) is well displayed during the analogue years
In addition with the conflicting and variable types of air masses in the same location, note heavier precipitation in the battle zone below.
Winter 2016-17 Upper Wind Anomalies & Projected Storm Tracks
The upper wind anomaly pattern from all analogue winters shows a marked difference in jet preferences and placing upper Lows and ridging when compared to a typical La Nina pattern. While the semi-permanent eastern Canadian Low is represented by the lobe of negative anomalies south of Hudson & James Bays; the most predominate departures in the upper wind anomalies materialized over western Canada and the Northwestern US. It's almost like the typical La Nina upper wind trough pattern shifts back west at times and creates the negative departures over that region. Referring to the typical La Nina map (above), the ridging is dominant on the West Coast of Canada and to a lesser extent, the US which would negate the coldest of winters.
Resulting Storm Tracks This Winter
What do the models have to say about the winter? Mild to warm everywhere if you look as of November 2016
||PAC calib. prob fcst
Forecasted precipitation trends for the winter generally follow the analogue years trend
||PAC calib. prob fcst
I'll be back at times when notable storms and/or temperature changes are expected to affect the region along with other historic storm information for the winter!
Making weather fun while we all learn,
Bill Deedler - SEMI_WeatherHistorian