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  • Updated

Friday, July 30th, 12:30 P.M. 

After a warm start to the day, temps will soar close to 100° in the Portland metro area this afternoon/early evening. We are keeping an eye on some clouds and showers over the Cascades this afternoon. I can't rule out the chance for a brief shower or thunderstorm in the metro area or central valley this afternoon and evening.

High pressure will slowly back off over the weekend, but we will still have a southerly wind overhead. Thin smoke and high elevation clouds will be possible at times, and isolated storms could fire up during the afternoons & evenings along the Cascades and east of the mountains. Highs should trend back into mid 90s to upper 80s Saturday and Sunday.

High pressure will continue to inch away from the Pacific Northwest next week, resulting in cooler temperatures. Afternoon highs will slowly trend back down into the 80s, with overnight lows in the upper 50s and low 60s. 

  • Posted

7pm Tuesday…

Hopefully you’ve paid close attention to our forecasts the past few days.  If so, you’ve finished up any project that requires dry weather and are now ready for a week of rain.  No, it’s not going to rain for the next 168 hours non-stop.  Instead, we’ll see a succession of wet Pacific weather systems moving into the Pacific Northwest.

After a very wet September, the faucet has shut off this first half of October.  We’ve seen little/no rain the past 10 days in the Portland metro area

Rain PDX Last 10 Days

And of course it’s been a very cool 1st half of October; temperatures are running 5 degrees below average at PDX so far… THIS HAS BEEN THE COLDEST 1ST HALF OF OCTOBER IN PORTLAND IN MY LIFETIME!  Only two have started colder, October 1968 and October 1949.  Those were followed by some interesting winters…just throwing that out there.  I highly doubt what happens the first two weeks of October means anything about the upcoming winter.  Notice the last few Octobers have been wetter than average

October Rain Stats

A cool upper-level trough (dip in the jet stream) is sitting in the Eastern Pacific and moves a bit closer tomorrow

ecmwf-nw-z500_speed-1248800

Tonight a weather system is sitting offshore; it’ll move inland Wednesday morning.  That system will be quickly overtaken by a cold front by tomorrow afternoon.  So we get two waves of rain tomorrow.  Behind that cold front, Thursday and Friday will feature the usual cold showers mixed with sunbreaks.  Friday night and Saturday a quick-moving trough spins up a surface low pressure system offshore.  Models are showing quite a slug of rain and gusty southerly wind with this one.

ecmwf-nw-z500_speed-1486400

That said, I don’t see any hints that we’re entering a real stormy pattern with multiple areas of deep low pressure tracking along the coastline.  We’re just going to see a parade of wet and breezy  systems moving overhead.  In October, in this pattern, it’s possible to get those waterspouts or weak tornadoes too if the pattern is just right.  We’ll be on the lookout for that.

Now that you’ve finished planting your spring bulbs, garlic, or cover crops, you’re probably wondering how much rain is on the way?  Quite a bit!  The WRF-GFS from UW shows less than 2.50″ in the western valleys ending next Tuesday

pcpt.180.0000

ECMWF, GFS, & GEM models all show somewhere between 1.50″ and 3.00″ in the western valleys of Oregon and SW Washington.   Maybe 5-10″ wettest parts of Cascades and Coast Range.  This isn’t enough to cause flooding when spread out over a week, but it’ll help recharge groundwater I suppose

This is the reason that I’ve been saying to “wrap up all your dry weather projects” by tonight.  It’s going to be quite wet over this upcoming week.

What about more dry days?  Models are suggesting we get some sort of upper-level ridging over the USA West Coast starting a week from now.  All three of the above models show a strong ridge right over us 8-10 days out.  Here’s Friday the 25th

It’ll be interesting to see if we get a setup we’ve seen twice this autumn; a trough suddenly comes across the ridge, pushing it back to the west and putting us under cold northerly flow.  There are a few hints of that in the 12z ECMWF ensemble chart; some ensemble members take quite a dip in the 2nd week.

tseries_850t_000-360_Portland (2)

To wrap it up…enjoy your inside time this next week.  And enjoy the gentle Pacific Northwest rains splashing on your roof.

Chief Meteorologist Mark Nelsen

  • Posted

Well, it’s time…time to “Fork Winter”.  Winter is cooked & finished west of the Cascades.   Put a fork in it!

Wayne requested I formally admit Winter 2019 is over during the 10pm newscast.  I assumed it was obvious this time around.  It’s so late in the season and we have 60s coming up later this week.  By the way, thanks again to John Rinier for that nice huge wooden fork!

Capture

What does “winter is over” mean in our climate?

Mark Winter is Over1

What could we still see?

Mark Winter is Over2

Now that first one is VERY unlikely, especially considering I don’t see any cold airmasses approaching in the next 10 days.  Typically I’ve put the fork in winter during late February, and of course it’s relatively easy to get a brief wet AM snowfall in early March.  Far less likely in late March.  Of course we can still get a frost the 2nd half of March, but we’re done with those low-mid 20s for the season.

Remember we’ve seen some strong wind in April recently.  Peak gust of 56 mph in early April 2017 during a rare late-season windstorm.

So yes…it’s time to get your snow tires off, uncover your faucets, and open up your crawl space.  Spring is on the way!

Mark Winter is Over13