A Dry October…So Far

October 18, 2015

10pm Sunday…

I just noticed we’ve still only had .43″ rain at PDX since the beginning of the month

MarkOctoberRain

Of course it’s only the 18th and anyone that has lived here very long knows the wet season can kick in quickly in the last week or so of October.  As a result it would be premature to say it’s going to be a real dry October.  That said, I don’t see much rain between now and next Sunday.  That means less than 1″ in the bucket with just the last week of the month to go.  It could end up being like 2011 or 2013.

This shouldn’t be a real surprise in a strong El Nino fall.  I used the great NCDC anomaly plot tool to make a map showing precipitation anomaly during strong El Nino Octobers. That would include 1957, 1965, 1972, 1982, 1987, 1991, 1997 and 2009.

ElNino_Oct

Look at the drier than normal Pacific Northwest west of the Cascades.  Novembers are similar with an even more pronounced dry anomaly.  Many of those years we saw ridging and/or split flow…like what we have been seeing in the maps for the next 10 days.  I remember 1997 was right after I got married…lots of east wind and sunshine with mild temps.

ElNino_Nov

What about December?  Different story.  In many of those years wetter weather showed up during the month

ElNino_Dec

There you go…pretty strong signal for drier than normal weather through Thanksgiving.  That doesn’t mean DRY in late fall,  but drier than normal.  We’ll see how it turns out.

Today was a crazy weather day at the extreme northern edge of the metro area.  Okay, not really metro area but pretty close.  A band of rain set up just to our north and sat over the same area for many hours.  While we saw little or no rain today down here in town, it was dumping buckets of rain in St. Helens and Woodland.  Take a look at the totals:

MarkRain_NorthMetroDownpours

Good for you folks, a soaking is much-needed for our trees and shrubs.  I don’t see that anytime in the next 6 days though.  We have a weak and splitting system both Monday and late Wednesday.  Other than that most likely dry through Saturday.

Chief Meteorologist Mark Nelsen