January 2018: Much Different Than 2017!

January 8, 2018

9pm Monday

As I mentioned almost a week ago, the weather the past couple of weeks has been very S-L-O-W.  Check out how different the first week of the month has been compared to last year!

Winter Snow_Ice Compare

So far this winter (beginning December 1st), we’ve seen temperatures near normal, but it’s sure been a bit drier than normal.  Most obvious has been the lack of mountain snowfall.  You see all of Oregon is at/below 50% of average “snow water” for this date:

Snowpack Oregon Plus Facts

At this point last winter we were finishing up our 2nd ice storm of the season with two more to go.   That was the weekend snow then ice event (very similar to what just happened Christmas Eve).  The big snowstorm followed just two days later (a Tuesday evening).  So far this month is running warmer than the past 4 Januarys…yes, quite a change.

Looking ahead, we are still in a split-flow pattern early this week, with big rains falling way down in southern Oregon.  That continues the next two days, then a more organized Pacific frontal system moves inland Wednesday night and Thursday.  This gives us a nice rainy/windy 12 hours…ah, back to normal!

Then an upper-level ridge of high pressure pops up over the West Coast through the MLK weekend.  East wind SHOULD clear out the metro area for some sunshine Saturday and Sunday, although we’re still deep in inversion season so it won’t get much above 50.

There are signs of a pattern change which now appears to only be 8-10 days away.  Models and their ensembles want to develop upper-level troughing over the western USA or at the least a wet/stormier westerly flow.  I’m talking sometime after next Tuesday, depending on the model.   Note the ECMWF ensemble 500mb height anomaly for NEXT week and the FOLLOWING WEEK (the 2nd half of January) shows the lower heights along the entire West Coast and a much warmer eastern USA:

And the same two-week precipitation anomaly maps show a wetter than normal West Coast:

This WOULD be the change to typical La Nina conditions many of us have been looking for if it comes to fruition.  We’ll see.  The ECMWF is pretty clear, check out the 850mb ensemble chart; excellent agreement on those temps going down beginning on the 16th. NEXT week is consistently cooler than normal at 4,000′ in the Cascades.

ecmwf_850mbtimeseries

This could mean we’ll finally start building a good base of snow in the Cascades.  What we DON’T see in the next 8-10 days is a pattern that would get snow/ice in the lowlands.  So it’s probably safe to say the first three weeks of January will not be featuring any snow/ice events.

Chief Meteorologist Mark Nelsen