Download RaysWeather.Com 2016-2017 Winter Fearless Forecast

Author: Dr. Ray Russell
Founder and President
of RaysWeather.Com
Date: October 15, 2016
RaysWeather.Com 2016-2017 Winter Fearless Forecast
Background
We had an impressively warm summer and early fall. The first frost has not even occurred for most of
the Southern Appalachians, with the exception of deeper valleys on the nights of October 11 th and 12th.
This year's "leaf season" is the latest in my 25 years living in Boone. As a result, it seems that
anticipation for winter weather is suppressed across the region. But one good cold snap will rev up the
anticipation.
Through the years, the RWC Fearless forecast has performed better than most; however, after a nearperfect 2013-14 forecast, both 2014-15 and 2015-16 were less than stellar to say the least.
Table 1: Accuracy of Last Year’s RWC Fearless Winter Forecast
Location
Forecast
Snowfall
Asheville, NC
Banner Elk, NC
Beech Mtn, NC
Boone, NC
Hendersonville
Hickory
Independence, VA
Jefferson and West
Jefferson
Lenoir
Morganton
Sparta
Spruce Pine
Sugar Mountain
Waynesville
Actual - Forecast
20"
67"
110"
54"
15"
9"
29"
35"
Actual
Snowfall
11"
38"
70"
25"
11"
6"
17"
15"
11"
12"
31"
27"
105"
19"
5"
8"
14"
19"
66"
9"
-6"
-4"
-17"
-9"
-39"
-10"
-9"
-29"
-40"
-29"
-3"
-20"
(Actual reports even within each location varied from site to site. I chose a snowfall total that fairly
represented the average for each location.)
Overall, actual snow totals were one-half to two-thirds of the forecast amounts. Temperatures were
forecast to be slightly below average but were actually slightly above average. However, several aspects
of last year's forecast did work out; we predicted: 1) a late start to winter (wow, was that true!), 2) that
the bulk of snow would come in January and February (that worked out), and 3) that it would be a
strong El Niño season but that El Niño would wane by the end of winter (an accurate prediction). So in
essence, the players lined up on the field correctly but underperformed expectations. We expected a
couple of big storms in the core of winter; the ingredients never came together. It happens to the best
of long-range forecasts.
Summary of the Fearless Forecast for Winter 2016-2017
Snow lovers will hope we are wrong; however, most signals at this point indicate a drier than average
winter with less than average snowfall and temperatures near average.
 20-25% less snow than the long-term average
 Temperatures averaging near to one degree above long-term averages.
Below are forecast totals for many locations in the Southern Appalachians. (Note: The forecast snowfall
total includes snow/ice falling between October 2016 and May 2017.)
Table 2: Specific 2016-17 Snowfall Forecasts for Selected Locations
Location
Asheville, NC
Banner Elk, NC
Beech Mountain, NC
Boone, NC
Galax, VA
Hendersonville, NC
Hickory, NC
Independence, VA
Jefferson and West Jefferson
Lenoir, NC
Morganton, NC
Mt. Airy, NC
Old Fort, NC
Sparta, NC
Spruce Pine, NC
Sugar Mountain, NC
Waynesville, NC
Wilkesboro and N. Wilkesboro
Wytheville, VA
Expected Total Snow/Ice for
Winter 2016-2017
10"
34"
70"
30"
15"
6"
5"
16"
20"
5"
6"
9"
6"
16"
19"
70"
9"
8"
17"
Happy Skiing and Snowboarding! We’ll keep you informed with the most reliable day-to-day forecasts
for the Southern Appalachians and Foothills all winter.
This forecast does not come out of thin air. It comes from serious analysis; continue reading for the
explanation.
Fearless Forecast Rationale
ENSO Analysis
As always, the first data points for a Winter forecast are the current state and forecast for the El
Niño/Southern Oscillation (ENSO). ENSO is a measure of large-scale weather conditions in the Equatorial
Pacific. It fluctuates between El Niño (associated with warmer than average sea surface temperatures in
the Equatorial Pacific) and La Niña (associated with colder than average sea surface temperatures in the
Equatorial Pacific).
Currently, the ENSO is classified as Neutral, but it is bordering on a weak La Niña. Figure 1 shows the Sea
Surface Temperature Anomaly from October 7, 2016. In spite of warmer than average Sea Surface
Temperatures (SST) across much of the Atlantic and Pacific Oceans, you see a thin band of cooler than
average temperatures in the Equatorial Pacific (the darker blues). Those cooler ocean temperatures may
be the beginning of a weak La Niña.
Figure 1: Sea Surface Temperature Anomaly 10/7/2016
(from www.ospo.noaa.gov/Products/ocean/sst/anomaly/index.html)
In contrast, last year at this time, one of the strongest El Niños on record was in progress. The El Niño
weakened in late winter and ended abruptly in Spring, 2016. A slow drift toward La Niña commenced
during the summer. That trend may result in an official classification of La Niña in the next couple
months (but barely). From there, it's about a 50/50 chance of ENSO remaining as a weak La Niña
through the coming winter or drifting back to neutral conditions. Figure 2 below shows current ENSO
model predictions. To be classified as a La Niña, the index in Figure 2 needs to be -.5 or below for 3
consecutive months.
For simplicity sake, we'll call the ENSO forecast "Weak La Niña"; the difference between an index of -.4
and -.6 will make little practical difference in our winter forecast.
Figure 3 shows snow data from Boone, NC. You see
seasonal snow data for 57-years classified by ENSO
type (Strong El Niño through Strong La Niña). The
graph also shows the long-term average and a 10year moving average. Note that the average
snowfall for Neutral Winters is only 1" greater than
Weak La Niña Winters.
Based on expected ENSO conditions, we chose 10
Best Fit Winters. All these winters were either
Neutral ENSO Winters but shaded on the negative
side of the index or Weak El Niño Winters with
index values less than 1. The Best Fit Winters are:
2013-14, 2007-08, 2005-06, 2003-04, 2001-02,
1996-97, 1990-91, 1985-86, 1983-84, 1974-75.
Figure 2: Forecast for ENSO (from
www.cpc.ncep.noaa.gov/products/
analysis_monitoring/enso_advisory/ensodisc.html)
Average total snowfall in the Best Fit Winters in
Boone, NC, is 32.2", 22% less than the long-term
average of 41.1". Also, only 2 of these winters had snowfall greater than the 10-moving average at the
time. Figure 4 shows the Best Fit Winters relative to their 10-year moving average.
Figure 3: Total Winter Snowfall in Boone, NC, Classified by ENSO (ENSO classifications derived from
www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml)
Figure 4: Best Fit Winters Total Snowfall Compared to Their 10-year Average.
Figure 5 compares Best Fit Winter Snowfall with all Weak La Niña Winters and all other Winters. Note
that all three classifications are similar in months other than January and February. This usually results
from drier than average weather in the Southeast U. S. La Niña winters tend to lack consistent transport
of energy from the Equatorial Pacific region into the Gulf and the Southeast U. S. Instead, the Pacific
flow is directed toward the Northwest U. S. and Western Canada and then across thousands of miles of
land before reaching the Southeast—that's a much drier flow pattern. See Figure 6 for a depiction of the
typical La Niña pattern in winter.
Figure 5: Snow totals from our Best-Fit Winters (2013-14, 2007-08, 2005-06, 2003-04, 2001-02, 1996-97,
1990-91, 1985-86, 1983-84, and 1974-75) compared with all Weak La Niña Winters and
all other winters. Snow totals shown are from Boone, NC.
La Niña winters can be relatively cold
for the Southern Appalachians
because of the predominant
northwest flow. They are also prone
to "northwest flow snow events" that
favor the west side of the
Appalachians for snowfall. But the
greatest factor in our winter may be
dry conditions. Our exceptionally dry
late summer and fall will "aid and
abet" a continuation of less than
average precipitation well into
winter.
Figure 7 compares average
temperatures in our Best Fit Winters
with all Weak La Niña Winters and all
other winters. Note that there's very
little temperature differences between
the three lines (so close it was almost
impossible to label all the lines
clearly!). However, the Best Fit
Winters and the Weak La Niña Winters
tended slightly colder than other
winters.
The main takeaways from the analysis
of ENSO forecast for the coming winter
are:
1. Moderate confidence in less
snow than average.
2. Temperatures in our Best Fit
Winters tend to be slightly
below average.
Figure 6: El Nino Winter Climate Pattern
(from www.meted.ucar.edu)
Figure 7: Average temperatures from our Best-Fit Winters
compared with all La Nina Winters and all other winters.
Temperature data is from Boone, NC.
Climate Change
While we have hinted at effects of Climate Change in our previous Fearless Forecasts, we have never
specifically addressed that issue. First of all, climate change is real. If you are interested in a good source
of scientific data and analysis on the subject, see http://climate.nasa.gov/evidence/. But two items
demonstrating effects of climate change are shown in graphs below: Diminishing Arctic Ice (Figure 8)
and Average Temperatures in North America (Figure 9). July 2016 was the warmest month ever
recorded (at the time), only be exceeded by August 2016. 2016 has been amazingly warm compared to
any year in recorded history. The areal extent of Arctic Sea Ice is persistently at or less than 2 standard
deviations below the 30-year mean.
Figure 9: Average Temperature in North America (from
http://data.giss.nasa.gov/gistemp/news/20160912/)
Figure 8: Extent of Arctic Ice (from
nsidc.org/arcticseaicenews/)
However, the effects of climate change are not linear or uniform in either time or space. Warming, that
has been experienced across most of the world, has not evidenced itself as strongly in the Southeast U.
S. A report in https://data.globalchange.gov/report/nca3/chapter/southeast/figure/southeasttemperature-observed-and-projected analyzes data in the Southeast U. S. through 2012. It will be
interesting to see the same result holds after the last couple years are added to the dataset. Figure 10
shows average annual temperature in Boone, NC through 2015. The Boone data is consistent with the
globalchange.gov report. (The "Dust Bowl Years are clearly evident in the 1930s and 1940s.)
Figure 10: Average Annual Temperature for Boone, NC
However, even though temperatures have not yet shown warming since the 1980s, the amount of snow
overall has definitely decreased as shown in the Figure 11.
Figure 11: Average Annual Temperature in Boone, NC
Regarding the winter forecast as it relates to climate change data, our takeaway is to shade snow totals
lower than the 57-year average but favor temperatures not far from long-term averages.
The North Atlantic Oscillation Wildcard
Every year, the North Atlantic Oscillation (NAO) is the wild card for long-range winter forecasts. Without
belaboring the details, the NAO is the North Atlantic's distant cousin of ENSO. (See
https://climate.ncsu.edu/climate/patterns/NAO.html for details on both the Arctic Oscillation and NAO.)
I know of no reliable way to forecast the NAO three to four months in advance. If the ENSO state tends
toward neutral, the NAO tends to produce even more variable results in the Eastern U. S.
Summary
Long-range winter forecast is always a risky proposition. Don't put much stock in this or any other longrange forecast. But here's what we think:
 Moderate confidence in a drier than average winter.
 Moderate confidence in less than average snow.
 Less confidence in temperatures near or slightly above average.
Yes, there will still be skiing in the Western North Carolina!!!