high pressure

6pm Wednesday...

Today was a great late October day; early fog/clouds then afternoon sunshine.  Temperatures peaked out around 60 in the metro area, perfectly normal for October 23rd.

Looking at all the maps/charts/models this afternoon, the most obvious feature is a persistent upper-level ridge near the West Coast of North America for at least the next 7-10 days.  One weak weather system slides through the ridge Friday for clouds and a few sprinkles/shower, but that’s about it.  Take a look at the current pattern at 500 millibars (around 18,000′)

Mark Jet Stream

Behind that weak system, the ridge pops up again but farther west.  This gives us cool northerly flow again; like we have seen twice so far this fall season.  Although this time the core of cold air is farther east.  The view Saturday…

Mark Jet Stream2

This setup in the cool season (we’re just about there) typically features very dry air coming down from the north or east.  Low relative humidity = not much cloud cover or valley fog.  So this weekend will feature abundant sunshine and a “cool-ish” feel.  That’s perfect pumpkin patch weather.  Our wet ground will be drying out nicely.

That ridge is probably going to remain near or just west of the West Coast through next week.   And it’s quite a block in the atmosphere.  Look at the high/warm anomalies stretching north to the Arctic Monday afternoon (red/pink colors).  On the backside see those low/cold anomalies from Hudson Bay all the way down to Baja California!

eurmon29th

Jumping ahead to NEXT Friday (the 1st), the ridge is still there.  Maybe a bit farther west

eurfri1st

These last two images are from the EPS (ECMWF ensembles), but other models are similar.  The screaming message here is that we’re going to be quite dry for the next 10 days.  We’ll probably see a gusty east wind develop after Saturday as well.  That plus dry air should keep fog to a minimum.  Take a look at the WRF-GFS cross-section that covers Saturday afternoon (right side) to next Wednesday afternoon.  Lots of easterly flow, especially early in the period.

kpdx.x.th

This will be our first drier than average October in 6 years.

October Rain Stats

It’s interesting that during the Autumn of 2013 we saw a similar rainfall setup; a very wet September then a dry October.  That also happens to be the last time we were in ENSO-neutral conditions leading into the winter.  That refers to no El Nino or La Nina in the tropical Pacific.   Speaking of…I’m working on some winter thoughts this evening.  I should be able to get a post done for that by early next week.

Enjoy this last weekend of October!

Chief Meteorologist Mark Nelsen

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