Travel Forecasts

November 23, 2015

11pm Monday…

Lots of people heading out on the road Tuesday and Wednesday…those will be the worst travel days weather-wise across the Pacific Northwest.

All dry Wednesday afternoon and beyond, so travel home Friday-Sunday will be good region-wide.

MarkTraffic_RoadsWinterNorthwest

 

MarkTraffic_RoadsWinterNorthwest2

 

MarkTraffic_RoadsWinterNorthwest3

Drive carefully the next 24 hours!

Chief Meteorologist Mark Nelsen


ECMWF Weekly Maps

November 23, 2015

3rd run in the past 10 days showing quite a bit of ridging lingering near us to the north and east.  Very interesting that WeatherBELL forecast this “classic” El Nino pattern for a winter average.

Weeks 1-4, click on each for a larger view

While examining the dailies it looked less ridgy to me in that last week, with heights actually a bit below normal overhead.  The 32 day rain total for the Willamette Valley is about 4″ with the ensembles and only around 2″ on the control run.  That control run only showed 1′ or so of snow in the Cascades…we’ll hope that’s not the case.  The ensembles had 2-3′ of snow in the Cascades by Christmas Eve (Day 32)

Big picture:  Warmer than normal mountain temps are possible along with drier than normal weather through the next 2+ weeks.

 

Chief Meteorologist Mark Nelsen


Is It Going To Snow In the Lowlands? No

November 22, 2015

9pm Sunday…

The most useful indicator for snow chances the Portland Metro Area the next few days will be the web site  http://isitsnowinginpdx.com/  This is one of my favorite sites; which 364.5 days of the year displays this:

 

Capture.PNG

Looking for a day off work or school Tuesday…it’s pretty unlikely that’s going to happen.  The colder models have slowly been coming around to the slightly warmer ECMWF and GEM models for Monday night and Tuesday so…

  • Steady rain develops in western Oregon/Washington Monday evening.
  • It turns to cold showers daybreak Tuesday morning
  • Sticking snow at that time reaches the lowest point around 1,500′.  That’s the top of the Coast Range summits, Welches area, and the very top of Bald Peak possibly.
  • Anywhere else in the hills could see a “sloppy mix” of snow/rain showers around daybreak but no accumulation with temps above freezing.
  • The rest of us just see a few light & chilly showers tapering off through the day with mainly dry conditions by Tuesday afternoon
  • Traffic in the lower elevations will not be affected by snow this week; continue with your usual and customary Thanksgiving Preps!

I do expect 5-10″ in the Cascade passes by Tuesday midday, which means snowy driving through at least midday Wednesday.  Then the snow will gradually work off the roadways.

Why am I so negative about low elevation snow?  Model 850mb temps have ever so slowly risen to around -4 to -5 with the precipitation Tuesday morning.  That’s not lowland snow material.  We need -7 with onshore flow, and it doesn’t help that our ocean is running several degrees above normal.  The air will be coming in off that ocean Monday night and Tuesday morning.  I notice the WRF-GFS maps are looking less and less snowy…this evenings’s run:

or_snow72.84.0000

and our RPM evening run:

RPM_SNOW_00z

Beyond that we should just be dry and chilly (but sunny) Wednesday through most of the holiday weekend…very nice.

Chief Meteorologist Mark Nelsen

 


Will There Be Skiing For Thanksgiving?

November 20, 2015

Good news this evening…there will be a limited opening at 3 Oregon Ski Areas tomorrow.  And I do mean LIMITED.

That said, you can go up, have some fun in the (ahhh…) sun, plus enjoy drinks/food/entertainment.  But you won’t slide on the snow too far.  At least it’s a start.

Timberline will open their Bruno beginner lift, Meadows has the Buttercup lift going, and Bachelor opens just a terrain park accessed by a lift.

You can see why the terrain will be limited to a few swaths of snow; the current snow depths at the base areas:

  • 10″ Mt. Hood Meadows
  • 15″ Mt. Bachelor
  • 19″ Timberline

Typically you need 25″ or more to open at least a few lifts and 50″ to open the majority of resort acreage.

So will we see SOME sort of real opening for Thanksgiving weekend?  It’s going to be a close call; totally dependent on just one more snow event in the next 8-10 days.  That’s later Monday and Tuesday.  Right now this is what I’m thinking:

MarkSnow_MtHoodFcstThe ECMWF and GEM models today were drier than this, but the GFS has been wetter (whiter?).  This 5-9″ forecast then is more or less an average of the two.

Assuming we get less than a foot, it’s still going to be tough to open another lift or two.  Since we don’t see any good system other than this in the next 10+ days,  all hope for some skiable terrain in the month of November is riding on Monday’s system.

Now you skiers/snowboarders don’t need to get all worked up (for now…) since it’s definitely not unusual to see ski areas remain closed over Thanksgiving.  Take a look at Mt. Hood Meadows base total from past years on November 25th (next Wednesday).  This year I’m guessing it’ll be 15-20″ by that time.

MarkSnowPack_MeltingQuickly2

IGNORE THE BANNER, that is a graphic from a blog post last year at this time.

Look at 2007 and 2008!  Terrible start, but those were BIG snow years with great skiing, especially 2007-2008.  It just took awhile for things to get going.

So my gut feeling is that we will see extremely limited terrain available for snow play through the Thanksgiving Weekend.

Chief Meteorologist Mark Nelsen

 

 


ECMWF Monthly Run

November 19, 2015

Hmmm, the past two runs (Sunday and last night’s) of the ECMWF run out to 32 days shows the dramatic pattern change will stick around.  That’s the change from very wet to very dry.

We know what’s happening over the next week…upper-level ridging to our west and we’ll be in cool northerly flow.

500za_week1_bg_NA

But then look at the following 3 weeks, ridging slides over and/or northeast of us in southern Canada.  with action apparently going by to the south:

500za_week2_bg_NA

500za_week3_bg_NA

500za_week4_bg_NA

I looked at the daily maps on the WeatherBELL site (can’t show them here) and it definitely is not a DRY pattern, but drier than normal.  Those maps also show cooler than average temps.

There you go…remember it’s just one run (two in this case) of one long-range model.

Chief Meteorologist Mark Nelsen

 


Colder & Drier Next 7-10 Days

November 18, 2015

11pm Wednesday…This first half of November has been extremely wet to the north and west of the Portland metro area.  Here in Portland precipitation has been about average and a bit below normal (so far) in southern Oregon.

MarkRain_NW_TotalsThose Washington and coastal rain totals have been amazing.  11″ at Olympia just a little past halfway through the month…

But things are about to change…I think splitting systems and upper-level ridging nearby will be the dominant theme for the next 10 days.

Next week (Thanksgiving Week!) ridging to our northwest will allow a surge of colder air to slip south.  That happens Tuesday and Wednesday.  Models earlier today were VERY cold, and I didn’t jump on that right away.  This evenings runs of the GEM, ECMWF, & GFS are a bit more reasonable with a very chilly, but mainly dry pattern most of next week.  You get the general picture here:

MarkJetStream

Is it cold enough that we could see snow?  Possible, but as of now I’d lean towards scattered showers Tuesday and/or early Wednesday and then just turning mainly sunny and cool heading into Thanksgiving.  That’s definitely subject to change since we’re talking about something 6-7 days away, thus the reason I’m not all excited about it yet.

By the way, the 15 day ensemble charts from the GEM/GFS/ECMWF all show the ridging developing early next week hangs around for the next two weeks, but flopping more right over us or just north.  Here are the 500mb height anomaly maps for around December 3rd…two weeks from now.  Click on each for a larger view:

The good news is that the weekend looks really nice with abundant sunshine, comfortable days, and chilly nights!  We should see the most widespread frost so far over the weekend.

Chief Meteorologist Mark Nelsen

 


Windstorm Wrap & Possible Gorge Snow Tonight

November 18, 2015

9am Wednesday…

I had two days off and flew back into PDX around 4pm yesterday…a bit bumpy!  A huge change to go from warm and sunny southern California to pouring/sideways rain on the way home.  Then 30 minutes after I got home the power went off for the next 5 hours.  My wife didn’t seem to appreciate it when I remarked something like “this great!  Better than coming home to boring 45 degrees and cloudy…”.  She just doesn’t share the weather geekery!


 

Tuesday’s windstorm was a rare event in the western/central Columbia River Gorge and then out into the Columbia Basin.  The 69 mph gust (near ground level) at Bonneville Dam was the strongest wind I’ve seen at that location.  In fact I can’t remember a damaging westerly wind event in the past 20 years in that area.  Even the sensor at Vista House, all of 18″ out from the stone wall, somehow recorded a gust to 48 mph (direction is broken) from the southwest.  Biddle Butte, at 1,400′ above Cape Horn, had a gust to 59 mph.  I haven’t seen that the past few years either.  Due to those strong winds lots of trees fell across or near I-84 so the freeway has been closed for about 12 hours eastbound.

In Eastern Washington it gusted to 71 mph at Spokane; more damage/outages in that metro area than the 1996 ice storm.  I also saw reference to that gust being the strongest non-thunderstorm wind gust on record for them.  Don’t know if that’s true or not.  But a huge windstorm for the Inland Northwest.

Of course for much of the Portland Metro area the wind wasn’t anything out of the ordinary for November, lots of gusts 30-40 mph, barely even worth of a wind advisory.  This was a Gorge and East of the Cascades event.

11_17_PeakMetroGustsPDX actually gusted to 43 mph; the 40 was a mistake.  Note the Troutdale profiler (in place for research this winter and next) shows 60-70 mph wind just 1,500-2000′ above the surface

11_17_Profiler_HighlightedWind

The pressure gradients were amazing for this event.  17 millibars from Eugene to Olympia shows the potential was there for much stronger wind in the metro area.  A typical guess for south wind in our area is 3.2 X EUG-OLM gradient.  That gives gusts 50-60 mph in our area.  We underachieved a bit.  And 27 millibars from North Bend (OR) to Spokane!  About the highest I’ve seen.

Models showed a very tight gradient ahead of the cold front, maybe a little weaker than what actually showed up westside and definitely underdone a bit in Eastern Washington.  Here’s the 4pm forecast from yesterday morning’s WRF-GFS:

11_17_WindStorm12hrWRFFcst

I checked the 4/3 km high-res run for the western/central Gorge and that didn’t capture the big surge of wind.  We still have some things to learn!


 

WHAT’S AHEAD?

We have a weak system moving through the area tonight on a totally different track.  No dramatic rain/wind issues with this one, because it’s a weak surface low coming right across the central Willamette Valley.  The bulk of the rain/snow is headed south of the Columbia River…maybe .50-.75″ of rain overnight total in the metro area, then drying quickly Thursday.

There is one interesting part; with the surface low approaching wind turns easterly in the Gorge and light easterly in the metro area.  That means snow will fall to relatively low elevations in the central/eastern Gorge.  Note the morning WRF sounding for Hood River at 7am Thursday:

hdrvr.27.0000.snd

Expect 1-3″ snow up around 500-1,000′ in the central/eastern Gorge overnight.  Just rain at the west end.  It could even be white for the first time this season down in Hood River by sunrise.  Winter is getting closer!

Chief Meteorologist Mark Nelsen