Wet & Windy Monday, Then Mild November Weather Ahead

November 12, 2017

7pm Sunday

So far November has been cooler than normal in Portland and rainfall just slightly below normal…the temps:

It appears the middle & 2nd half of the month will likely be milder (compared to normal).  That’s because all models are advertising a typical onshore-flow pattern with wet weather systems frequently moving through the area the next 10 days.  None of these the next week appear to be a big storm by any means.  In fact I don’t see a setup for widespread flooding or damaging wind.  But we DO have one strong low pressure system moving by offshore overnight and the back side of it will swing onto the Washington coast by midday tomorrow (the poisonous tail of the bent-back occlusion!).  That’s some serious weather nerd lingo there.  That has prompted NWS to issue a High Wind Warning for the Coast and Wind Advisory for the valleys:

The 980-985mb low is a little farther offshore than we would typically “want to see” for a significant windstorm in our area.  And here in the valleys the isobars (lines of equal pressure) are not oriented right for a big south wind in the valley.  Still, gusts 30-40 mph can bring down a tree just about anywhere or cause some outages…so expect some of that tomorrow.  Strongest wind both areas will likely be around midday.  If you are right on a beach or exposed headland I suppose you could easily get a gust higher than 65 mph too, and somewhere north of the Columbia River on the beaches I could see gusts above 65 mph too as that occlusion comes onshore midday.  Those numbers are for 95% of the coastal population.

One other thing about tomorrow, it IS the type of day (based on several parameters) in which we have seen funnel clouds or worse out at the coastline in the past.  No, I’m not saying there is going to be a tornado on the beaches Monday, but SOME TORNADOES IN THE PAST AT THE COASTLINE HAVE OCCURRED WITH THE METEOROLOGICAL SETUP WE HAVE IN PLACE TOMORROW.  We’ll be keeping an eye out of course.

Beyond tomorrow we have a few colder systems coming through which means snow in the mountains!  Keep in mind there is still around 20″ on the ground at 6,000′ (Timberline Lodge).  ECMWF projects maybe 2-3 feet of fresh snow above 4,000′ through Friday.  We’ll see if the weekend precipitation either shows up or is cold enough for snow up there.

This should be enough to open more runs/lifts at Timberline and maybe enough to get Meadows open for the weekend before Thanksgiving too.  And there appears to be plenty more valley rain and mountain snow beyond as we head into Thanksgiving Week.  Take a look at the ensemble-average upper-level flow (lines) and departure from normal (colors) this Thursday.  These are the ECMWF ensembles.

Cool troughing over us later this week means near normal temps and plenty of mountain snow.  Then 4 days later…the Monday of Thanksgiving Week

Troughing is a bit farther offshore, this is a mild and generally wet pattern.  Then Thanksgiving itself…11 days away:

All models keep showing ridging over the Western USA, but we appear to be on the edge of that, and over the past few days they have been shoving it farther east.  Again, this is a wet pattern with near normal temps.  Maybe a bit above normal in the lowlands since we’ll have a lot of cloud cover (no cold nights).  Looks great for mountain snowpack building too.  When the weather pattern appears to be somewhat settled in the longer-range, I show this “12 DAY TREND” graphic in the 2nd half of the 10pm newscast.

Right now some of you may be wondering if there’s any chance for snow/ice at Thanksgiving (my wife just asked today!).   Or if there will be any sort of dry spell so you can finish up an outdoor project.  That’s why I created this graphic…to give you a “peek” farther ahead without any sort of detail.  No one can forecast exactly what’s going to happen in two weeks (or even 10 days), but in times like this we can sometimes give a general idea of the trend.

Chief Meteorologist Mark Nelsen