Today - Transition day as high pressure starts breaking down... Warmer temperatures and partly cloudy skies are expected. Low pressure from an earlier storm retrograded west and forms a new weak low to the west/ southwest, and this low is expected to pull some moisture in from the Pacific mainly...

Monday through Wednesday - Low pressure to the west pushes moisture and some instability across the area from out of the southwest. Showers are expected mainly each afternoon, with isolated thunderstorms across the Roaring Fork Valley/ Aspen, and the rest of western Colorado, best across the San Juan Mountains. Snow levels will run around 9,000 (early/ night) to 10,000 feet (mid-day) Monday and Tuesday, with some mostly light snow above those elevations, 4" max in a 24 hour period for the higher mountain areas above 10,000 feet. Snow levels drop on Wednesday as the weakened and colder core of the low moves across the area.

LONGER RANGE: Late next week we start warming up under unseasonably strong high pressure ridging across the western US, and this holds for most of the rest of October. No major systems are expected to pass through, though we may see showers now and again with weak perturbances in the flow aloft. Around Halloween/ early November there are signals that we may see a tropical system move into the picture, with significant rains and high mountain snows (mostly near/ above 10,000 feet) possible if this gets swept in across Colorado. Summit County could get hit nicely with heavy and great base building snow, as mid and upper mountain Aspen-Snowmass would also. We will be watching... CM 

Fri, August 31st, 2018 (begun this article)
Sunday September 23, 2018 (I finally finished it!)

MODOKI EL NINO = bad, REGULAR EL NINO = usually good, WEAK EL NINO to ENSO Neutral = can be good (due also to other factors)! There are many possibilities with the last one (the one we think is coming) but we will nail it down for you! 

Central and Western Colorado, Aspen-Snowmass to Durango
FALL and WINTER SEASON FORECAST FROM SNOWFORECAST.COM!

...WHAT IS THE FORECAST?...
OCTOBER - (Slightly above average snowfall and below average temperatures) Early season cold and October snows are expected for the ski resorts, with most snow and coldest temperatures being east of Vail Pass and the divide, but more than the average of 10" of snow that Aspen averages in town (more on the mountain), as storms drop in out of Canada for the most part, carrying the bulk of moisture and cold air to northern Colorado and to the east of the Vail Pass and the divide. There will be enough cold and snow to test out snowmaking equipment. The early snows will open the usual 10,000ft+ resorts early, and help to chill the soil for good base building as we move into November... We also expect the usual transition season cut-off and closed low pressure systems to move in from the west and deliver some surprises (snow then best for Aspen and southwest Colorado)... "Cut-off" means the low is cut off from and not being pushed around by, the storm steering flow (usually at 500mb).
NOVEMBER - (Near to above average snowfall, and below average temperatures) Near to above average early season snow overall across the region and no snow level issues, with cold systems out of Canada diving through and hitting all areas, as high pressure ridging offshore of the west coast allows storms to develop and move south from out of Canada, moving in with below average temperatures and some extreme record cold. We expect some early opening days on good bases. Snow is expected to be well preserved as colder than usual air helps to protect the snow...
DECEMBER - (Near to above average snowfall and near to below average temperatures through mid December, then dropping off to near average snowfall and near average temperatures in late December on some good bases). Some significant snowfall events through mid and maybe into late December, and near to below average temperatures should combine to be great for Christmas-New Year skiing/ boarding, then incoming storms start shifting to the south on a different storm track, with lighter snows for Aspen and good for southwest Colorado as we move into the holidays.
JANUARY ONWARD, MORE COMING SOON - ? Stay tuned, but a brief synopsis: Dry for most of January with above average temperatures as high pressure ridging builds in, and the east coast gets hammered with cold and snow. Storms return in February with near to above average snowfall and near average temperatures for Aspen-Snowmass, then March through the rest of the season looks near to warmer than average in temperature, with below average snows. April could produce some big storms and powder days to pass through the region, building the late season snowpack. More details are coming, and I will be naming resorts and forecasting long range snow totals. CM

...WHAT ARE THE FACTORS AND OPINIONS?...
Here are my August 31 observations: An El Nino that "wants" to happen, but meager warming to even some cooling in the key Nino regions (recent), and a mostly neutral status (currently) is not showing much hope for any El Nino pattern that may be classified as moderate or strong. In fact, I will say that we will not see a moderate or strong El Nino SST pattern this 2018-2019 season, and the NOAA forecasted weak El Nino is looking like a "maybe".
And, my September 15 observations: Latest guidance indicates that the El Nino SST anomaly will be weak, at best, in my opinion. Here is why: Cooler eastern Pacific waters (Nino 3.4 region)/ Subsurface waters heat content (180-100W Lat) has decreased/ and the current pattern is showing mostly a general cooling and not warming overall, though in the last 7 days, eastern Pacific surface waters off the coast of Ecuador (means "Equator") have warmed . Its mid September and this El Nino event should be a bit more evident. Its not. Even NOAA has backed off a bit with a 65% chance of El Nino formation, instead of the 70% they had called for early on in the summer when this anomaly looked more likely. For them to back off a bit like that indicates definite lost confidence, and this is not surprising, as I lost confidence in it occurring myself, back in July. Things work a bit slower in these large organizations, while us "loose cannons" (whatever in the hell that means) can blast off at will. Haha.


*An El Nino is still favored according to the above Climate Prediction Center chart*



*We have seen some areas of cooling in the Nino 1+2 and 3 regions, as this El Nino struggles to form. This is indicating cooling in the subsurface waters, which is a factor that is looked at for potential SST's*



*As of Sep 12, there is some warming going on again in the referenced "Nino 3" region, so overall there is a positive SST anomaly, but mostly less than +.5 (in yellow on the above chart), which is the threshold that needs to be met for 3 consecutive months before an actual El Nino pattern is recognized. For now we are in an "ENSO neutral" status.

SOLAR MINIMUM: In terms of sunspot activity, there is currently almost none, or even "none", zero, zilch, nada, many days. Decreased or zero sunspot activity also affects our weather patterns. The chart below shows how we are in a solar "grand minimum" right now:


We have seen some recent serious weather extremes this Summer of 2018, and have no reason to believe that we will not see similar extremes this fall and winter in North America:

From extreme heat in Europe, notably northern Europe:




To extreme snow and cold in August:

 NOAA: So to reiterate, NOAA (the National Oceanic and Atmospheric Administration) was forecasting a 60% likelihood for formation of an El Nino SST pattern this fall, and a 70% chance for the winter, 2018-2019, while now those forecasts are down to 50-55% and 65-70%, respectively. Large organizations like NOAA are not going to go backward on the forecast (decreased % chance), like this without very good reason, like, "its not happening like we thought it would guys"...

SNOWFORECAST.COM: At this point, a "weak" El Nino SST anomaly is the forecast from NOAA. I have believed since June that this would be a weak El Nino pattern that sets up, based on the afore-mentioned trend, but am now wondering if this El Nino will even show up at all. We think that the weak El Nino or no El Nino is going to turn out well for Aspen and southwest Colorado as it is combined with weak sunspot activity (solar minimum) for expected colder air (and stronger storms that reach the area) this winter overall. If an El Nino, weak, does form, it is looking more likely to be the Modoki version, which on average, sucks (dry) all across the western US. Thankfully, as a weak factor (there are other factors), a weak El Nino of any kind will have a "weaker" influence on the weather patterns we see this fall and winter, THANKFULLY. We are also looking (currently) at a weakly negative PDO (Pacific Decadal Oscillation, more of a long term state of ocean water temps), which will not help in the El Nino department. Neutral to "very weak El Nino" is what we are forecasting as we move into fall and maybe through the winter, at best +.5 which is barely classified as an El Nino. As well, with the Grand Solar Minimum, expect the unexpected, and so far, that has proven true in many parts of the world. How will all of these factors; Weak El Nino, or even "ENSO Neutral" SST anomaly, neutral PDO, GSM (solar), and my own intuition, affect the southwest and western Colorado forecast? Just scroll back to the top to find out!

Feel free to share this, but please cite credit to snowforecast.com. Thank you! CM

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Some References:
COLD AND SNOW:  https://www.theweek.info/index.php?newsid=3760 (Salzburg, over 1 foot of snow in August!)
HEAT:  https://www.washingtonpost.com/news/capital-weather-gang/wp/2018/07/17/scorching-scandinavia-record-breaking-heat-hits-norway-finland-and-sweden (90+ degrees in Norway, all time record high temps!)
Great resource for current SST’s and anomalies:
https://www.tropicaltidbits.com/analysis/ocean/
International Research Institute:
https://iri.columbia.edu/our-expertise/climate/forecasts/enso/current/?enso_tab=enso-cpc_plume
Latest ENSO Discussion:
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.php
Space Weather ("Solar Minimum"):
https://www.swpc.noaa.gov/products/solar-cycle-progression
NCEP model forecast SST anomalies (1 model forecasting La Nina):
http://www.cpc.ncep.noaa.gov/products/NMME/current/tmpsfc_Seas2.html
The ONE outlier model forecasting La Nina:
http://www.cpc.ncep.noaa.gov/products/NMME/current/images/NASA_GEOS5v2_ensemble_tmpsfc_season2.png
Loads of the latest SST charts from ESRL, knock yourself out:
https://www.esrl.noaa.gov/psd/map/clim/sst.shtml
Best anomaly chart (in my opinion):
https://www.esrl.noaa.gov/psd/map/images/sst/sst.anom.hov.gif

Detailed ENSO Discussion from NOAA:
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf
More info/ charts on Modoki El Nino:
http://www.jamstec.go.jp/frcgc/research/d1/iod/enmodoki_home_s.html.en
El Nino/ La Nina years/ ONI:
http://ggweather.com/enso/oni.htm
A GREAT resource for "no BS" historical ski season info:
http://bestsnow.net/
Latest PDO and history:
http://research.jisao.washington.edu/pdo/PDO.latest.txt