Lots of Weather Action!

October 21, 2010

Here’s the 8-14 day 500mb height forecast and anomaly from CPC.  You can see the troughing forecast to persist off the West Coast and strong jet stream aimed towards us…looks wet!  In fact I see the 00z GFS has pretty much destroyed any chance of a several-day dry spell.  Our wording “Rainy Season Begins” on the 7 Day forecast the first part of this week seems to be correct at this point.

Tonight’s system is pathetic, tomorrow night’s should be quite a bit juicier, and Saturday night’s the strongest.  In the last 24 hours models have backed off on the position of the strong low Saturday night and Sunday morning.  It’s now projected to be a bit farther northwest, but still very deep…955-960 millibars.  That’s respectable even in mid-winter.  Now if we could just get one of those say, on a line from Astoria to Yakima???  A statement I probably wouldn’t repeat on-air I suppose.

Snow levels still drop Monday and Tuesday for some snow in the passes.

By the way, we’ve dropped the old Typepad weather blog.  We started that in late November 2005.  In fact the very first few posts are here on this blog if you go back to that month.  But there’s no reason to be paying for both.  We changed over to WordPress about 18 months ago and I’ve transferred most of the old posts.  Some did not make it; it was a REAL pain to get that info over here.  Unfortunately I see a good chunk of December 2008 didn’t make it.  Couldn’t it have been a July???

Chief Meteorologist Mark Nelsen

A Quick Post

October 20, 2010

Got a bit behind tonight; but after lots of long posts, it’s probably time for a quickie now anyway.

Southerly surge moving up the Coast tonight…one last taste of the warm season onshore-offshore flow pattern before we head into the colder season I suppose.

Models have converged on 3 organized weather systems impacting us between now and Sunday.  First one is pathetic and may or may not give us a shower tomorrow evening.

2nd system is more organized, although associated with a decaying low pressure system too.  That one moves through Friday night.

3rd system is by far the strongest.  Depth of the low and position are still getting shifted around by various model runs.  The 00z GFS has the low much closer and deeper as it runs into the northern tip of Vancouver Island early Sunday morning.  We’ll see how the next 48 hours of model runs change things.  If the stronger solution plays out, that means high winds on the Coast (60+ mph gusts) Saturday night.

After a break the middle of next week there appears to be more action as we head into the Halloween weekend.  That’s a long ways out though!

Chief Meteorologist Mark Nelsen

One More Spectacular Day

October 19, 2010

Today was the best so far during this sunny period in my opinion.  A cool start, but then a noticeably warmer afternoon.  Looks like the western suburbs were warmest with highs into the lower 70s.  Tomorrow should be just a few notches higher since easterly flow is increasing pretty quickly this evening plus the atmosphere overhead will warm up too.

Not much change in the rest of the 7 Day forecast; lots of action beyond Friday.  I don’t see any real strong storms coming through, but still a good slug of rain with a cold front sometime between late Saturday and Sunday afternoon. 

Snow levels are still on tap to drop down below 4,000′ Sunday evening or night.  It’ll be the first snow of the season at the passes.  I checked the records and see Government Camp gets snow in October about every other year.  Last year was a big one with an early start to the wet season…19″ that month.  Snowiest October up there since 1991.

Chief Meteorologist Mark Nelsen

Sunshine Continues…

October 18, 2010

What a great sunset!…I got a bunch of pictures from viewers tonight…this one from the Turner area southeast of Salem.  It’s been an incredible stretch of weather the last week with some really nice sunrises and sunsets.

I have relatives in town from Hawaii (you can probably take a wild guess that’s not where I’m from), and apparently they have hit the jackpot weatherwise;  a good 7-10 days of mostly sunny weather that began last Tuesday and continues through this coming Thursday.  We’ve been lucky to have just enough offshore flow and low enough dewpoints to keep the fog at bay. 

The lack of fog (for more than a few hours in localized spots at least) continues through Thursday since we’ll get increasing offshore or easterly flow tomorrow and Wednesday.  In fact for those two days the flow goes easterly at all levels below 5,000′ except here at the surface.  That should give us some warming…we’re playing it pretty conservative here with 68 the next two days, but it could easily be in the 70-73 degree range if easterly wind were to actually surface at PDX either tomorrow or Wednesday afternoon.  Thursday should be cooler as we lose the offshore flow.

The really BIG story is the well-advertised change coming up this weekend.  Models have been showing this for a few days…the beginning of the rainy season.  By that phrase I mean that we are done with many consecutive dry days and warm (65-75) temps.  Sure enough, when you look through the maps for the next 7-10 days there is no dry period after Thursday.  Now most years it happens somewhere between mid-October and mid-November.  Last year it was wet from mid-October onward.   This year it should be right on time.

So get anything done in the garden, painting, gutters, etc…that you don’t want to do during a November dry spell;  which usually tends to be quite a bit cooler.

As for details on the weekend weather…I don’t see a big windstorm, but a rainy and windy weekend.  Models are all over the place with low pressure depth and placement.  The trend on the GFS the last few runs is to bring heavier rain farther south right on into Oregon.  But it’s only Monday…we’ll see.

For the skiers and snowboarders;  the snow level stays high until Monday and Tuesday when it plummets below 4,000′ for the first time this season.  Winter is almost here in the Cascades.

Chief Meteorologist Mark Nelsen

Winter Weather Meeting Saturday

October 14, 2010

Good times ahead for the weather enthusiast.  It’s time for the 18th annual What Will the Winter Be Like meeting at OMSI.  Hard to believe we’ve been doing this since the early 1990s!  It used to be held in a small conference room and maybe 15-20 people would show up.  Now we regularly see more than 100.  I wouldn’t be surprised if we approach 300 this year.

You are invited…as the event is open to the public.  The meeting basically consists of 3­-4 forecasters getting up and giving their thoughts about what might happen during the upcoming winter.  A lot of times they are wrong, sometimes they are right, but there is always lots of good discussion.  Last year one person forecast 6 snow events in Portland; you are welcome to ask him about it this year!  Also lots of discussion about La Nina, MJO, QBO, and other big phrases.  The event is held in the auditorium and lasts about 2 hours.  I will be there, but I just give a review of the previous year’s weather.  You’ve seen my thoughts about the upcoming winter in previous posts about La Nina.  You can click on the tab above labelled LA NINA 2010.  Another member or two of the FOX12 weather team may show up too.

Other meeting details are here at the…Oregon AMS website.

We have an incredible stretch of late October sunny weather on the way tomorrow through at least the middle of the week.  Enjoy the sunshine!…I will be off tomorrow, but back at work Monday.

Chief Meteorologist Mark Nelsen

Bright Sunshine and Strong Wind

October 13, 2010

We saw our first strong Gorge wind of the season in the far east Metro area and Western Columbia River Gorge today.  The pressure gradient from Portland to The Dalles was up to -6.7 millibars at one point…pretty good for mid-October and just a sign of things to come as we get deeper into Fall.  Of course the big east wind season is in the winter, generally November to February, then it disappears quickly in early March.  The reason is the cooling of the continent while the ocean stays about the same temperature (a few degrees cooler).  Cooler land = heavier & cooler air overhead = high pressure.  Higher pressure east of the Cascades and lower pressure west means wind funnels through the only sea-level gap in the Cascades (the Gorge).  The wind then spreads out and slows rapidly, in most weather patterns, as it exits the Gorge.  Today was a prime example of a “gorge-only” wind event.  Sometimes the east wind also goes over the Cascades, bringing more widespread gusts to the entire Metro area.

Of course the result was a bright and warm Autumn day…temperatures into the lower 70s around town today.  I had more than one comment from the public that just loves this weather.  Cool and clear in the morning, warm and sunny in the afternoon.  The easterly wind also gave us great visibility too.

The wind goes away this evening…in fact the gradient is already down to around 2+ millibars.  We go to weak onshore flow tomorrow, so expect a drop in the temps as a front approaches, but still a real nice day, until we get some evening sprinkles.

The 7­­­­-10 Day Outlook still looks very boring for us weather weenies.  In general a ridge of high pressure or split flow through at least the middle of next week.  One change in the weather will be a cooler atmosphere Friday through Monday.  That plus relatively dry air and mostly clear skies at night could mean the first frost for outlying areas.  I mentioned this on Monday and it still seems likely even now.

Chief Meteorologist Mark Nelsen

Cool Nights Return

October 11, 2010

A chilly night ahead tonight!  At 10pm the entire metro area (except right in the city) is in the 40s, some of the outlying areas already down in the lower 40s.  We’ll definitely have more 30s in the morning and in more places that haven’t seen 30s yet.  At my home I haven’t been below 42 yet this season and I’m already down to 42 right now.  There are some scattered high clouds moving through from a warm front well to our northwest, but there isn’t much else to inhibit the strong radiational cooling.  

Some spotty fog is definitely likely in the low spots overnight.  Offshore flow is gradually developing, but gradient is just now beginning to turn to easterly, so that won’t help too much.  We get some easterly wind through the Columbia River Gorge and out into the Metro area tomorrow, so it’ll be warmer and dry once the fog gets mixed out.  Then it’s on to our strongest east wind of the season so far on Wednesday morning.  Somewhere around 5-6 millibars easterly gradient through the Gorge.  That should give us gusts in the 30-35 mph range east metro and 40-45 mph in the western Gorge.  Thursday the offshore flow dies down as a very weak front approaches. 

We get some clouds and maybe a few showers late Thursday night or Friday morning, otherwise I don’t see a good chance for rain in the next 7 days.  Definitely no imminent start to the rainy season (many consecutive days of rain).  Actually it looks real boring the next 7-10 days.  Enjoy the sunshine!

By the way, tomorrow is the 48 year anniversary of the Columbus Day Storm…Wolf Read’s site is the best at taking an “exhaustive” look at the storm:


Chief Meteorologist Mark Nelsen