Whew! 70s In The Cascades

January 17, 2013

Well if today didn’t scream INVERSION!  I don’t know what did.  30s and 40s in the Valleys; 60s and even 70s in the mountains.  Check out the warmest I could find in the Cascades:

MarkInversion_70s

It also hit 74 at Abernathy Mtn near Castle Rock and 73 at Marys Peak near Philomath.  I added the disco ball for effect…

There was one big surprise today.  The east wind was strong enough (at least above the surface) to dry out the lowest 1500′ of the atmosphere all the way down to Salem and up to Woodland.  So mostly sunny skies throughout just about the entire Willamette Valley.  What a way to screw up a low cloud vs. sun forecast.  Much better than the other way around!

What about tomorrow?  Since we only have east wind at the surface east of I-205 and dewpoints are around 30 degrees, I think we’re headed towards widespread fog and freezing fog for the Friday morning commute.  Models say the easterly flow blasting through the Gorge (gusting 50-60 mph right now) will slow to a trickle by daybreak.  Not sure if I believe that since the gradient has been around 6 millibars all day and shows no sign of slackening.  But our gloomy Friday forecast is based on the fog developing tonight in the lower elevations and sticking around most of tomorrow.  As a result, our forecast is only for 40 at PDX tomorrow.  There is also no sign of east wind returning much this weekend, so we clouded up the weekend forecast too.  What a pain to figure out fog vs. clouds vs. sun each day…

All models agree on the ridge breaking down Tuesday and Wednesday with a cool and wet trough moving through.  Then another colder trough late next week.  The ECMWF and GFS have snow down into the hills again about 8-9 days from now (around next Friday-Saturday) with that 2nd trough.  850mb temps are down to about -6.  Of course that is still quite a ways away so it could end up either colder or warmer as we get closer.     You can see good agreement on the cool trough looking at the 12z ECMWF 500mb ensemble height anomaly for Day10 (a week from Sunday):

ecmwf_240

That will leave just 5 days to go in January…who knows what happens in those last 5 days, although hints are that ridging returns around that time (2 weeks from now).  Note the same map 5 days later shows that idea:

ecmwf_360

The 18z GFS ensemble chart is similar:

tseries_850t_000-384_Portland

And the 12z GEM:

gem_360

which never inspires a lot of faith in me anyway. 

This January will likely go down as a drier and colder month than normal, probably the coldest January in about 20 years here.  I’ve got 2 other thoughts:

1. If it’s the coldest in 20 years, it’ll be without any decent cold weather records.  Just consistently cool through just about the whole month.

2. Other than that, not much to write home about this month…move along to February.

Speaking of, since I haven’t shown enough maps, here is Week 3 and Week 4 from last night’s ECMWF monthly run:
500za_week3_bg_NA

500za_week4_bg_NA

Chief Meteorologist Mark Nelsen


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