October 2017 Northern Hemisphere Preliminary Seasonal Snow Forecast

Wow is it that time of year already? Arapahoe Basin just opened in Colorado and the North American snow season is underway. Europe’s glaciers are open for skiing and Japan is getting it’s first couple of snowfalls. Winter is coming, so now we need to take a little look at what is happening in the world’s climate at the moment.

ENSO

ENSO is currently in a Neutral phase. Most, if not all forecasts show a cooling in ENSO region temperatures to potentially La Niña levels. Below is a NMME + IMME ENSO plume.

The North American Multi Model Ensemble(containing 8 North American models, including the NASA, CFS, GFDL and CMC models) average shows a Borderline La Niña. The International Multi Model Ensemble(CFS, MetFrance, ECMWF and UKMO Seasonal models combined) shows more cooling than the NMME, and goes for a Weak La Niña(which is stronger than a Borderline La Niña).

This is the ECMWF ENSO plume. The ECMWF seasonal forecast is considered one of the best seasonal models in the world and is a very exclusive model. The EC averaged is going for a Weak La Niña.

Some noticed an increase in Nino 3+4 SST anomalies over September. However as this chart below illustrates, subsurface sea temperatures in the Niño region of the Pacific are still colder than normal.

If the cold subsurface water anomalies go to the surface, we could be getting a proper La Niña. SOI is indicating a La Niña and cloudiness anomalies near the IDL agree somewhat. Trade winds have been weaker than normal, which doesnt occur in a La Niña and has been causing all the warming of Niño SSTAs in September. I am personally favouring a Borderline to Weak La Niña (-0.6 to -1.0).

Siberian Snow Cover

The latest daily Siberian Snow Cover anomaly shows somewhat increased snow anomalies in Siberia. The latest EC Weeklies run shows somewhat decreased Siberian snowfall this coming week, neutral next week and somewhat increased Siberian snowfall in the two weeks after next week. The latest GFS run shows colder than normal temperatures over much of Siberia over this week and into the next. However the last few days of the GFS run shows a warming in Siberia. The Siberian High is currently stronger than normal, but is forecast to weaken over the next two weeks.

Pacific Decadal Oscillation

The PDO has recently been in a weak cold phase. Current EC forecasts show no major PDO signal in the North Pacific, with a major warm SST anomaly towards the tropics and another warm SST anomaly towards the Kamchatka peninsula. If we can get some cooler SSTAs, there might be an affect on the jetstream, like last season.

QBO

The QBO is currently in a negative or easterly phase. The SAO is currently in a positive or westerly phase. Short term EC shows a slight weakening in the QBO jet, but many commentators have said that the QBO will come back to increasing easterly anomalies. For information on QBO Impacts, look here.

Seasonal Models

This is the 500mb anomaly product of the EC Seasonal model, for months December, January and February. According to EC, both the European and Japanese Alps are subject to a higher chance of ridging. For Western North America, December brings troughing to the NW and ridging to the SW. January brings ridging to the region and Feburary continues that trend, except for Far NW USA and British Columbia.

The CFS forecast for DJF shows ridging for SW America and neutral conditions for the PNW and BC. It also shows a higher chance of ridging over the European and Japanese Alps.

JAMSTEC doesn’t have a 500mb anomaly chart, so I am showing the 2m Temp DJF chart. It shows milder weather across the US, except the Rockies that look colder than normal. The Japanese and European Alps look warmer than normal.

There seems to be somewhat of a consensus among these particular models, of a ridging and warm winter for the European and Japanese Alps. There isn’t as much as a consensus for North America.

Thank you so much for reading this seasonal outlook for the Northern Hemisphere.

Seasonal outlooks tend to have bias and errors, due to the fact that these forecasts are so far out. So don’t use these outlooks to make important decisions. These outlooks are meant to be interesting information, that can help to see what the season might be like.

This took a lot of work, so I appreciate your support. Starting from the first weekend of November, I will issue the European Alps Season Forecast, and then the Japanese Snow Season Outlook the next weekend, and then finally the North American Snow Season Outlook the week after. This timetable is fluid, but expect these outlooks around then. They will all be done by December. The plan for winter is to start the long term outlooks in Early December, and each region will get an outlook every 3 weeks. Again this is fluid and may change. This season will feature new Monthly Control maps. It will also include Climate Driver outlooks.

Thanks again for reading, follow me on Twitter @longrangesnow and subscribe to my email list by clicking on the tab on the main header above.

Stay Cool

Snowy Hibbo

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