Ski Season Update

December 1, 2014

So much for a nice November start to the ski season!  No Mt. Hood areas have been able to open anything other than a run or two.  But it’s a brand new month full of white possibilities…so what do I see?

1. At least one more week of temperatures continuing warmer than normal.

2. No pass elevation snow in the next week.  Great driving!

3.  More rain than snow will fall below the 6,000′ elevation.

4.  Snow WILL fall at times above 6,000′, so the base should gradually grow above Timberline Lodge and on the upper half of Mt. Hood Meadows.  Skibowl may be left out in the cold (or warm in this case) for another week or so.

MarkSnow_MtHoodFcst_2013

There were two reasons we didn’t see a decent snowpack start to build in November.  One is the persistence of ridging over or near the West Coast, which means warmer than normal upper-level temperatures.  So when we did get precipitation, more of it fell as rain than we would typically see.   The other reason is that we saw weak systems most of the month due to energy in the jet stream splitting at times.  The total rainfall at PDX was only about half of the November average.

So we need more precipitation and cooler temps.  Unfortunately I don’t see a change in the next 7-10 days.  There ARE hints that heading into mid December we could see cooler westerly flow and wetter weather.  Take a look at the GFS & GEM ensemble 500mb height anomaly for next Tuesday (the 9th)  gfs_8days gem_8days They are both similar.  But one week later, 15 days out on the 16th of the month?  Quite a bit different.  The GFS pushes the ridging to the east with a cooler and wet westerly flow…lots of Cascade snow. gfs_15days  But the GEM keeps strong ridging along the coastline for that entire week and it’s still there on that date

gem_15days

The ECMWF at 12z looked more like the GFS above…definitely wetter.

It’s possible a developing El Nino is affecting our “winter” weather pattern already.  As of today’s weekly ENSO update,  the ONI is now +1.0, which is on the border between weak and moderate El Nino.  The monthly ENSO diagnostic discussion comes out Thursday and they will probably say we are officially in EL NINO CONDITIONS.  Just to avoid arguing in the comments, here is NOAA’s definition:

nino

Note the last paragraph implies we are about to head into, or are already in, EL NINO CONDITIONS.

Chief Meteorologist Mark Nelsen