Stormy Weather Ahead; Winter Meeting Today

November 17, 2012


It appears that REAL November weather is on the way, with many storms/frontal systems ready to impact the Pacific Northwest in several different ways over the next week (and beyond).   The main issues (threats) will be possible flooding and/or damaging wind.

First, don’t forget the previous posting, the OMSI winter weather meeting starts in just 2.5 hours!  I’ll be manning the rafffle box.


Now, on to the weather:

We have a cold front just offshore this morning, with rain showers ahead of it in the mild airmass.  The steady rain with the front will be here in the middle of the day with a break behind the main rain band occurring in the late afternoon and evening.   This first system is pretty weak, it’s just “opening the door”…

From Sunday afternoon through Tuesday morning, a baroclinic zone (boundary between warm and cool air) sets up right over Oregon and Washington, first mainly over Washington, then sliding well down into Oregon Tuesday.  This is an “atmospheric river” event with plenty of moisture to work with; thus a flooding threat depending on where the heaviest rain falls.  

Our 12z RPM (sometimes too wet in the past, but not always) shows the heavy rain:

Several deep areas of low pressure will track along this zone during the period:

Low #1:  This one is somewhat weak, maybe even just an open wave (not a closed area of low pressure).  It is that cluster of clouds/rain behind the main cold front.  It’ll move up along Vancouver Island late this evening and very early Sunday morning.  A decent burst of wind/rain in the middle of tonight with this.

Low#2:  Much stronger/deeper low, maybe 982-988 mb runs right into central Vancouver Island late Sunday evening.  Strong wind at the coast tomorrow evening through the middle of night.

Low#3:  Similar strength and only 8-12 hours behind the first one as it rides along a baroclinic zone (frontal system) sitting just to our north.  Similar location for landfall, maybe a little farther south.

So if you want to go see stormy weather at the Coast, the 24 hour period from Sunday afternoon through Monday afternoon looks best.

Neither of these lows (as of this morning) is enough to give us a big windstorm, but gusts to 70 mph along the coast and 40-45 mph here in the valleys will be the strongest we’ve seen so far this season.

We’ll see about the rain, it’s always tough to know exactly where the heaviest rain will line up.  I remember exactly one year ago we had the heavy rain band sit right over us a little longer than expected the Tuesday before Thanksgiving, giving us some minor flooding.

Finally, snowfall in the Cascades.  Good news and bad news.  The good news is that we could see 10-15″ in the norhtern Oregon Cascades in the next 3 days. 

Most of that will be later today through Sunday morning and then again Monday night and Tuesday morning.  The bad news is that the Mt. Hood ski resorts will be in the warm part of the storm from Sunday evening through Monday afternoon.  Many inches of rain will fall all the way up to 7,000′ during that time.  You can see the difference on the map above; note most of the Washington Cascades on the colder side of the baroclinic zone more of the time equals much higher totals.  Add the new snow and heavy rain together and I’d gamble base totals won’t change between now and midday Tuesday.  Or, pray that the whole zone is 100 miles farther south and feet of snow will dump on Mt. Hood the next few days.

Okay, off to the meeting and on to exciting weather!

By the way, no sign of real cold air for lower elevation snow in the next 7-10 days…in case you were wondering.

Chief Meteorologist Mark Nelsen




Winter Weather Meeting Just 3 Days Away

November 14, 2012

Don’t forget, the best “wishcasting” of the year always happens at the annual Oregon AMS winter weather meeting…details are below.

As for our current weather…FOGGY.  Lots of dense fog developing this evening.  A perfect setup with clear skies, high dewpoints, and cooling temps.

East wind picks up the next few hours in the western Gorge, so a clear night on the extreme eastern edge of the metro area.

Latest 00z GFS is cooler Tuesday-Wednesday, more like the 12z ECMWF.  We may yet open up Timberline and Meadows for Thanksgiving Friday!  We’ll see.  Meanwhile, a great picture from Don Best this evening; sunset at Rockaway Beach.


20th Annual Winter Weather Forecast Conference

Saturday, November 17th 2012 @ 10 AM.
Oregon Museum of Science and Industry (OMSI), main auditorium, 1945 S.E.
Water Ave. in Portland.

This meeting is free and open to all ages of the general
public. Free parking in all OMSI parking lots.

The Oregon Chapter of the American Meteorological Society (AMS) is proud to
announce the 20th Annual Winter Weather Forecast Conference on Saturday, November 17th
2012 beginning at 10 AM in Portland. Meteorologists from across the Pacific Northwest will
once again descend on the Oregon Museum of Science and Industry (OMSI) to give their
prognostications for the upcoming winter. Will El Nino arrive, bringing with it warmer and drier
weather or will it remain at bay for what could be a “wild weather ride” this winter? Don’t miss
this ever-popular free public meeting. A $300 Davis home weather station will also be raffled
off at the end of the meeting.
Conference Rundown

Welcome & Opening Remarks:
Steve Pierce, Oregon AMS President

OMSI Update:
Jim Todd, OMSI Planetarium Manager

Review of 2011-2012 Weather:
Mark Nelsen, Chief Meteorologist – KPTV/KPDX

2012/13 Winter Weather Forecasts

Clinton Rockey – National Weather Service Portland
Kyle Dittmer, Hydrologist/Meteorologist – CRITFC
George Taylor, Climatologist/Meteorologist – Applied Climate Services
Jim Little, Meteorologist – Oregon Department of Forestry

Audience Question/Answer Session with Forecasters

Raffle – $300 Davis Home Weather Station & More

Please note — OMSI’s main auditorium will hold approximately 300 guests. Please arrive
early in order to be assured a seat. Once standing room capacity has been met, the only
additional viewing area will be from the hallway outside. For complete meeting details,
including overnight accommodations in and around Portland, please see the Oregon AMS
web site at:

CONTACT: Oregon AMS President, Steve Pierce at: or
503-504-2075. Oregon AMS web site:

Active Weather Ahead

November 13, 2012

Finally, some weather action is on the horizon.  It’s been a very slow Fall weatherwise.  The first 40 days were bone dry with lots of sun; of course that’s nice when it’s still warm!  Then around October 11th the rains moved in.  We had some early season snow in the Cascades before Halloween.  Remember the base totals up around 20-30 inches?  The warmer rain around Halloween washed that away.  Now the first half of November has been real dead.  We can’t even get a gusty east wind out of the Gorge!  Probably no one complaining about that one though.

Now it appears we have a change towards a stormier westerly or southwest jet stream type pattern.  One in which we get numerous storms moving in from one of those two directions.

The 12z ECMWF and the 00z GFS are both very wet from Saturday through the middle of next week.   Both have more typical (for November) deep surface lows tracking near the Pacific Northwest coast at times.  This is a pattern in which we can get strong wind at the coastline and sometimes inland as well.  Something to keep an eye on.  Right now I don’t see anything that makes me think “WINDSTORM 2012!”

Once we get to Sunday and Monday, all eyes will be on the Cascades for two reasons; skiing and travel.  Next week is a big travel week of course with Thanksgiving right around the corner.  The 00z GFS came in quite warm later Monday and Tuesday as a cold upper trough briefly amplifies well offshore.  If so, 24 hours of heavy rain could delay ski area openings beyond a week from Friday (the day after Thanksgiving).  Otherwise, all other models seem to point to plenty of snow in the Cascades Saturday through next week.

Speaking of wind and windstorms, I’m giving my usual post-winter wrapup this Saturday at the AMS meeting at OMSI.  I just finished the presentation.   One of the slides is below.  What’s been missing here in western Oregon lately?  I still think we are overdue for a windstorm.  We haven’t seen a southerly gust above 53 mph in 12 years!!!  Now from about 1995 to 2006 ASOS anemometers (the instruments at airports) were using a 5 second gust, which meant a bit lower speeds than before and after that time.  For example, in the 1995 storm the ASOS measured 62 mph, but the old, shorter gust recorder at PDX recorded 74 mph.  For the purposes of this graph though, even sub-53mph speeds for 12 years seems like a long stretch.  Will this be the winter?  We’ll see.  The good news is that most likely we’ll see it coming days ahead of time; as with the 2006, 2000, and 1995 storms.  The only windstorm that has sneaked up on us in the past 20 years is the “South Valley Surprise” of 2002.

Chief Meteorologist Mark Nelsen

El Nino Is Dead (Mostly)

November 8, 2012

Today CPC (Climate Prediction Center) officially pulled the plug on the possibility of El Nino this winter.  From late spring through summer, climate models tried to develop a moderate strength El Nino for the fall and winter.  El Nino is a warming of the equatorial Pacific, La Nina is cooling.  The whole package is ENSO (El Nino-Southern Oscillation). 

The equatorial Pacific did indeed warm during the summer to marginal El Nino conditions, but then it stalled and actually cooled back closer to normal.   The main region used to determine the status of ENSO is called Nino 3.4.  Here’s a chart of all the ENSO regions over the past year:

You notice the 3.4 region warms, then cools close to normal recently (right side).  Officially, El Nino conditions are  0.5 or higher in this region.  So it was marginal in the summer, but is definitely now on the warm side of “neutral” and it appears that will continue the next couple of months, which is all that matters for our winter. 

So what does it mean for this winter?  Well, out of the last 3 official neutral winters (2008/2009,  2003/2004,  & 2001/2002) two saw significant ice/snow storms here in the Portland Metro Area.  Now many would argue 2008-2009 was a La Nina winter since it was right on the line between La Nina and neutral.  Good point, only adds to the mystery if you ask me.  If you take the 3 neutral winters before that you find 2 more years in which we had some good snow/ice action.

About a month ago, I looked much farther back in history to see what kind of winters we have had when we have weak El Ninos or neutral years that are on the warm side (like this coming winter).  I saved that very detailed post as a tab.  Click on WINTER 2012-2013 THOUGHTS up above.

Chief Meteorologist Mark Nelsen

Athena The Storm; What a Dumb Idea!

November 7, 2012

Something really weird happened today in the meteorological world.  One weather company (The Weather Channel Company) decided, on its own, that winter storms would each get a name this season.  Of course most of you probably heard about this a month or so ago, but today the first storm “Athena” was christened…it’s the nor’easter heading up the coast.   This came to my attention today because we received a fancy little graphic from our weather software vendor (WSI).  They are owned by the same company…surprise.  Take a look at those names!  More weirdness…in my opinion.  It’s going to be REAL cute when people are dying from Blizzard PLATO or Ice Storm GANDOLF.  I don’t plan to use it of course, but thought you might like to see the list.

You can probably tell by the title of the post and my comments that I think it’s ridiculous…why?

  • If any one company/organization starts naming storms, then why can’t others?  Can you say CONFUSION?
  • The National Weather Service is NOT participating, they even issued a memo today forbidding their forecasters from using the names.
  • What areas does it apply to?  What kind of storms?  Just Nor’easters?  Big Midwest storms?  A wet storm on the West Coast that dumps 5 feet of snow in the Cascades or Sierra Nevada?  And who decides?  Apparently one corporation will?
  • Will a so-so storm along the East Coast get a name but a major storm in the N. Plains not get a name?


Moving on to current weather; cool air has moved in as expected.  Showers were very sparse this afternoon (as expected) too.  Now as an upper-level disturbance drops down through the offshore waters tonight and tomorrow, shower activity picks up at the beaches and in the Coast Range.  00z models keep insisting little or no rain makes it out of the Coast Range and into the Valleys; thus the dry forecast for tomorrow.  There is a chance a shower could bubble up overhead, but at least in November a surprise shower isn’t as big of a deal as it is in May or June!  No lawns to mow and no painting/staining of decks…

The air mass get’s progressively colder through Saturday with 850mb temps down to around -5c by Saturday morning.  That’s chilly even for winter; so with full sunshine Saturday we’ll still have a tough time hitting 50 degrees.  And either Saturday or Sunday morning’s we should finally get a frost in the city with the drier air/lower dew-point filtering in from the north behind tomorrow’s system.

There is a change in the longer range compared to the posting I made 48 hours ago and it’s all about location.  Models had been showing an upper level height anomaly out around 160W this weekend and beyond.  Now, after this weekend, it appears to set up slightly farther west, which means the cold trough I thought would sit near us most of next week will be offshore.  This is the ECMWF ensemble 500mb height anomaly for about 10 days from now, showing the trough centered well offshore.

If so, that’s significantly warmer.  This also has a major impact on the start of ski operations in the Cascades:


Other than a couple of inches Friday, no snow until Sunday night.  Then at best maybe 6-8″ up there through Tuesday.  Then with a new trough digging well offshore, we’re in mild southwest flow but most rain stays offshore.  If so, that means only 5-10″ on the ground a week from NEXT Friday, the 16th.  Not only will there be no skiing for the 2nd weekend of November, but probably not the 3rd weekend either, that’s the weekend before Thanksgiving.  This is not unusual.  I think the higher ski areas consider a Thanksgiving opening a nice start and anything before that is icing on the cake.  So no reason to freak out; but the point is no early opening for the ski season this year.

Chief Meteorologist Mark Nelsen

A SLOW Election Night in the Weather Center

November 7, 2012

Everything is working out as planned this evening.  A cold front moved through earlier this evening with very light rain.  But that was it.  A non-eventful front as expected.

Tonight was sure relaxing…in the weather center.   The news people had the busiest night of the year.  Wayne & Shauna were on the set (same room as me) from 4:00-11:30pm except for one hour from 7-8pm.  But there were no weather segments after the 6pm show!  It was a great evening to check out maps, return emails, schedule school visits, shop for cheap airfare for March (there isn’t any) etc…  I love big election nights!

Anyway, not much to report for the next 5 days, mainly dry with Thursday’s system curling well to our south, then a few pop up showers under the chilly upper-level low Friday afternoon.  Note how dry our RPM is for the next 3 days:

Temps will be quite a bit cooler now until further notice.

By the way, Mt. Hood Meadows was warmer than Portland today; 60 vs. 59.  Don’t worry, I already put a note in for next Monday’s report card with a big X; the expected breakout from low clouds to sun just ahead of the front didn’t materialize from Salem north.  I thought there would be more mixing.

Next week looks wetter, but not unusually cool.

Chief Meteorologist Mark Nelsen

Cool & Dry November Weather On The Way

November 5, 2012

Highlights This Evening

  • One more warm day tomorrow with temps well into the 60s
  • Enjoy it, I don’t see any more of the warm stuff on the way; last mid 60s until February?
  • Much cooler the rest of the week and into the weekend
  • Not much rain between now and Sunday!
  • First Frost is possible even in urban areas Friday or Saturday morning.

I was sick the last half of last week, plus the weather has been dead, so not much to talk about anyway.  But finally some interesting weather coming up over the next 7-10 days…hopefully.

5 out of the last 9 days we’ve tied or broken record warm low temps.  We won’t today since we’re already down to 54 at 9pm and it’ll be lower before midnight.  That’s a long stretch of warm nights!  Yesterday Salem and Eugene were into the 70s for record highs too.  It’s been nice to be outside with no jacket in November, but now it’s going to cool off.

The Big Picture
It appears a longwave upper-level ridge is going to be taking up residence out around 160W  off/on the next 10 days or so, which means a trough located most of the time along or off the West Coast.  There is amazing model agreement on this general plan in fact through the 10-14 day period.  Here are the 500mb height anomaly (all ensembles) maps from the 00z GFS, 12z GEM, & 12z ECMWF for 10 days from now: 

They all look pretty much the same don’t they?

Here’s the brand new 00z GFS model 850mb ensemble chart, very good agreement on below average 850mb temps through the next 9 days:

This means cooler than average weather returns.  We are just about into the time of year (mid November through early March) when “cooler than average” means real chilly.  So it’s going to be quite a change the next few days going from well above normal temps to a few degrees below normal.  And it goes without saying that after about November 15th, we watch very closely to see if that perfect snow or cold pattern will show up.  You usually want the ridge a little bit closer for an “arctic outbreak”, but with the ridge a little farther away, it can be a great snow pattern for the foothills and Cascades.  Right now nothing looks too interesting on the maps for the next week.  We have a first cold upper trough moving down over us Wednesday-Saturday.  We don’t get dry offshore flow, but even so it might be a cold enough atmosphere (-5 deg @850mb) that we get clearing and finally get a frost in the city (or at my house, I still haven’t been below 36…cheated…).  With an upper-level trough digging so sharply over us Wednesday and Thursday, the main precip action is farther south.  In fact the rain we have in the forecast for Thursday may never make it into NW Oregon east of the Coast Range as that system heads into California.

What about skiing? 
Very little moisture means little/no snow through Saturday, so no skiing for this 2nd weekend in November.  But with a cold trough over us next week, a couple wet storms could get some areas open for the weekend before Thanksgiving?  Think positive, but I definitely don’t see an early start to the ski season though this year (well before Thanksgiving).

Lower Elevation Snow?
This is the general pattern in which we would expect to see snow at least down to 2,000′, in fact I thought that would happen Thursday/Friday, but now just about all the moisture is farther south.   As of this evening, I don’t see anything on the maps through the next 7-8 days which would bring snow any lower than that.

Here’s what is NOT in the plan for the next 7-10 days:

  • Warm and Wet weather (we had enough of that for 3 weeks)
  • A Windstorm Pattern

Chief Meteorologist Mark Nelsen