Mild & Drier First Half of November

November 3, 2014

6pm Monday…

The screaming message on weather models/maps for the next 7-14 days is that we’re going to see a big slowdown in the weather.  An upper-level ridge of one sort or another, or split-flow, will dominate the western part of the USA for most/all of the first half of November.  That includes us of course.  The eastern USA will be unusually cold at the same time.  Sound familiar?  This is what we saw during a good chunk of last winter.  7Day_PulloutScene6

Now does that mean the ski season is “over” before it started?  Of course not.  This may be a transient pattern and we have the best Thanksgiving to Valentine’s Day ever recorded up there…we don’t know.  That said, it’s pretty obvious this will not be a ski season that starts unusually early.  Note the ECMWF meteogram shows little/no rain for a week starting this coming Thursday evening and what does fall will be mainly rain.  Snow levels the rest of this week are mainly at/above 8,000′:

ecm_meteogram

The GFS is similar: gfs_meteo

Not totally dry, but quite a bit different from the past 3+ weeks.

Last night’s run of the ECMWF shed a little more light on how long this pattern COULD last.  It implies the ridging along the West Coast will stick around for about 3 weeks.  Here are the Week 1, 2, & 3 500mb ensemble anomaly maps:

500za_week1_bg_NA

500za_week2_bg_NA

500za_week3_bg_NA

The ridge is still there from the 16th through 23rd of the month.  But then a slight change just beyond…

500za_week4_bg_NA

It’s not a return to a real wet pattern, but not a big ridge either.  Could be a cooler pattern where we get weaker/colder systems coming down from the northwest.  We’ll see.

Chief Meteorologist Mark Nelsen


GFS Upgrade Next Month

November 3, 2014

I’ve mentioned in the past the GFS (Global Forecast System) model has fallen behind at least one or two other models the past few years as the USA has fallen behind on some aspects of numerical weather prediction.  It’s widely acknowledged the ECMWF is the #1 global model most of the time.

But there is a glimmer of hope coming next month.  On December 9th, the GFS will see an upgrade.  I found this summary on a weather forum so I’ll just copy/paste the details:

-Finer horizontal grid, 23km to 12km
-High resolution deterministic forecast extended from 8 days to 10 days
-Output datasets available to 0.25deg in addition to current 0.5deg

And here’s what one poster in the UK thought about it…

– GFS still isn’t likely to verify as well as ECM because it will continue to run 4x daily with a lighter data payload. 

– Automated forecasts should be marginally better across the board and possibly noticeably better for some locations due to the increased resolution of the output datasets where they are used. In the UK locations on the south western peninsula may benefit significantly

What this doesn’t mean:
– A forecasting revolution. We’re at the stage and have been for a long time when finer model grids and higher resolution output datasets lead to marginal improvements

So what does this mean for us in the Pacific Northwest?

1. It’s true that this isn’t any sort of miracle cure, but the GFS should do a bit better than it has the past few years.

2. In areas with lots of topography it should help a lot…like right here!   The resolution change from 27 to 13km will handle the Cascades/Coast Ranges better.  Shorter distance between forecast points means better topography for the model to see.  Of course the Columbia River Gorge is far narrower than 13km so it still won’t be there, but at least it’ll be seen as a lower pass than just a dip in the Cascades.  That will help some in the winter.

WeatherBell is a subscription service that offers thousands of maps and we subscribe to it at FOX12.  They have put the parallel run on their website so you can compare maps.  Take a look at this morning’s GFS map for this coming Friday morning:

gfs_27km

and then the upgraded model

gfs_13km

Do you see the extra detail?  It’s quite noticeable in the Gorge area and southwest Washington.

Assuming the government doesn’t have some sort of issue implementing this, the new data will start flowing just over a month from now.

Chief Meteorologist Mark Nelsen