Gorge Wind Storm Dying Down

December 11, 2017

9pm Monday…

The most damaging east wind storm in the western Gorge the past 9 years is finally ramping down this evening…slowly.

Pressure gradients from Portland to The Dalles have dropped dramatically from 12 millibars earlier to only 7.3 now.  Generally the higher the number the stronger the wind.

Capture

Windspeed has been slow to respond, but it should continue to drop tonight and be in a more manageable and typical 50-60 mph range tomorrow through Thursday.  Maybe even lighter if we get lucky.

We haven’t seen such high wind for several days since the January 2009 event.  Take a look at the past 7 days down at Rooster Rock:

Mark Gorge Wind 7 Day Gusts

I don’t have all the numbers from Corbett but they were similar, peaking around 80-88 for several days.  Keep in mind that in most winters at that location gusts above 75 are rare.  Last year I think it hit 80 or 82 once.

The Vista House wind sensor is gone.  It was beat up for a few days and then wasn’t there when I drove by this morning.  Probably out in Troutdale somewhere…note the last few wind reports around sunrise.  It made one last stand at 7:06am and then that was it.

VistaHouseLastWind_12_11_17

The damage hit home today when a friend’s home was demolished by a fir tree last night.  While she was sleeping the tree crashed into her home,  impaling her in the abdomen.  She is still in the hospital and I pray for a speedy recovery.  I do know she’s a tough one!  I’ve always considered the east wind a nuisance (enough to move a couple of miles out of it) and somewhat interesting since it brings ice/snow, but that’s it.  This is the first time I’ve seen someone nearly die from that wind.  It gives you a different perspective as a forecaster…

This is the first time since that 2009 event we’ve seen lots of trees have falling for 3-5 days on homes, powerlines, and roads in a relatively small area up there.  It’s interesting windspeeds have NOT been exceptional in the Troutdale/Gresham area…just incredibly annoying.  That’s different from the 2009 event when the 60 mph gusts spread all the way out to Orient/Gresham/Troutdale areas.  But the weather setup has been the same otherwise:  A sharp upper-level ridge, extremely warm overhead airmass, and 10-12 millibar easterly gradient through the Gorge.

Looking ahead, the wind is still expected to stop Thursday night.  West wind will be breezy through the Gorge Friday.

Chief Meteorologist Mark Nelsen

 


2 Evening Questions: When Will the Wind Stop? What About Ice/Snow?

December 10, 2017

8pm Sunday

I was in 3 different public places today in the Gresham/Troutdale area.  The question was the same :  “I’m tired of the wind; I hate it.  WHEN is it going to stop?”

Answer:  Friday the cold east wind will be gone.   Bonus:  At least it won’t be quite as strong Tuesday-Thursday.

25152133_1150190618451601_900884798337528793_n

Today was day #4 of strong easterly wind across the central/eastside metro area.  That doesn’t count the previous day (Wednesday) when it wasn’t as strong out there, but everyone in the metro area saw at least SOME wind.  It appears there will be 3-4 more strong east wind days.  I drove by the Vista House wind sensor today; it’s bent a little more back against the building and far from horizontal.   There were plenty of people walking (stumbling & crawling) around though!

Wind Metro Peak Gusts East Wind

HIGHLIGHTS

  1. Cross-Cascade pressure gradient is now the strongest we’ve seen so far for this event at 8pm.  Over 12 millibars from Portland to The Dalles.  The wind is just as strong now as anytime since Thursday and will remain in the same range through at least midday Monday.
  2. There have been power outages that come & go as more trees fall.  Expect more of those tonight and Monday, then fewer downed trees with more reasonable wind Tuesday.
  3. Peak gusts continue in the 70-80 mph range in Corbett area and 45-60 mph range in “upper” Troutdale.  I see two home weather stations have gone over 50 mph up there today.  I think this is the first time I’ve seen it gust above 80 mph on multiple days at that Corbett sensor that has been in place for 4/5 years.  This is an unusual event even for such a windy place.
  4. The weather we’ve seen this weekend continues through Thursday for all of us…valley sun, mountain warmth, & a mild coastline.
  5. There is no sign of a stormy weather pattern, lowland snow/ice, or flooding in the next 7-10 days.  Our slow start to storm season ’17-’18 continues.

Check out those morning lows in the calm locations…some of these are the coldest of winter so far:

Looking farther ahead…I’m confident we’ll be back to showers/rain/clouds/mild temps by Friday. Of course then the question is:

IS THERE A CHANCE WE GET FREEZING RAIN OR SNOW DURING THE TRANSITION BACK TO WET & MILD?

Answer:  A very small chance, it’s unlikely we get ice/snow this time around…whew!

All models are in great agreement that a cold front swings through here in Friday.  That reverses the pressure gradient quickly.  In fact I expect a mild & gusty WESTERLY wind through the Gorge by Friday afternoon.  This is not the usual ice-storm setup with a low coming up from the southwest.  In this case the front is sweeping in straight from west to east.  It wouldn’t be cold enough for snow anyway since the air overhead will be very mild.  At this point models show some weak precipitation arriving Thursday night and early Friday.  Assuming we don’t drop down to freezing Thursday night we’ll be too warm in the metro area for freezing rain.  Assuming precipitation makes it into the Gorge early Friday morning and the wind hasn’t reversed yet, there could be a very brief period of freezing rain out there (central/east Gorge only).  Lots of assumptions though.  I’d give the chance of freezing rain in the metro area about 10% right now and a 50/50 chance of something brief in the Gorge.  So again, this isn’t the setup for an ice/snow event in our area.  Don’t change any of your plans for Friday.  It’s most likely we just have some light rain and Friday ends up around 48 in the afternoon.

Beyond that some snow will likely fall in the Cascades Friday (a little) and then rain or a mix of rain/snow at the ski resorts over the weekend.  Another shot of snow is likely the early part of NEXT week and then…the bad news…models are pushing another warm ridge overhead as we head into Christmas weekend.  That’s almost two weeks away.  Here’s the ECMWF ensemble average of 500mb heights on Christmas Day.  Don’t place bets on a snowy Christmas!

 

Chief Meteorologist Mark Nelsen


High Winds, Cold Nights, & Another Dry Week

December 8, 2017

6pm Friday

For such a “boring” weather pattern the details for the weather geeks have been fascinating the past 24 hours.  Consider that:

  1. Temperatures soared into the 50s on Mt. Hood today…55 at Timberline Lodge!  In fact a few spots in the western Cascade foothills were in the 60s.
  2. Meanwhile, as expected, temperatures in the lowlands have continued to drop as cool air becomes established in the valleys & Gorge under an inversion.  Today was the coldest day so far this winter at PDX.  That’s right, you need to go UP at least a thousand feet to warm up!

3.  That’s due to the end of the mild downsloping wind off the Cascades.  Now all that air moving from east to west across the state has to squeeze through a very shallow layer under the inversion through the Gorge.  Check out the metro peak wind gusts…all areas west/south/north mainly calm…

4. Yet within the Gorge and far east metro the wind has continued to pick up.  The wind at Corbett has gusted above 70 mph every 10 minute period since 3pm…that’s unusually strong even for them.  The raging wind continues through the weekend.

I notice temperatures in the mountains will probably warm a few more degrees by Sunday as 850mb temps rise into the mid teens.  The strongest wind event I remember in the Gorge was when 850mb temps got up around +18 in January 2009.  That really squeezes the air down and speeds it up.  By the way, I drove by the Vista House wind sensor at midday.  It looks beat up, bent down and back a bit, which accounts for the “low” wind speed there the past two days.  Combine the wind and cooling airmass coming through the Gorge and it feels like mid-winter out there.  Here are the 6pm windchill values.

Ice has also begun to form on Gorge waterfalls.  It will be a great weekend to check out the wind, waves, and icy waterfalls in the Gorge.  I found this just on the road to Vista House at midday:

And the river will look like this pic from Kirk Mattila.

With such a dry airmass and our long winter nights, temperatures in calm areas have been plummeting.  Check out the mid 20s in many areas this morning.  Expect more of the same the next few days:

 

This general pattern continues through about Wednesday next week.  That will be our 10th dry day in Portland.  However it appears things will be changing after that time.  The most reliable model and its ensembles show onshore flow (and the end of the cold east wind) Thursday/Friday next week as the strong upper-level ridge flattens and systems go by to our north.  This happens to be the one pattern that can minimize or eliminate the threat for snow/freezing rain as we go back to milder weather.  We’ll see how it pans out, but we might be back to gray and drippy conditions later next Thursday or more likely Friday west of the Cascades.

Beyond that, models are in disagreement whether we go into a cooler/showery pattern with the big ridge moving farther west offshore, or stay in milder westerly flow with weak ridging.  The net effect doesn’t appear to be a return into a soaking wet November-like pattern.  Note the ensemble average precipitation from the ECMWF is only 1″ in the week leading up to Christmas.

So enjoy at least another 5 days of dry weather with sunshine, then most likely we’ll turn at least a little wet and much grayer late next week.

Chief Meteorologist Mark Nelsen


Here Comes The Wind!

December 5, 2017

7pm Tuesday

I mentioned in Sunday’s post that we’re in this weather pattern for the long haul.  Now, two days later, all models are keeping us dry or almost dry through the beginning of many school’s Christmas Vacation.  That’s Saturday the 16th for many kids.  Some schools are waiting one more week though…it’s a bit staggered this year.   Regardless, I’m quite confident the weather pattern will be VERY slow the next 10+ days.  Check out the ECMWF model’s ensemble precipitation forecast.

ecmwf_24hrqpf

It looks extremely complicated but it’s really not.   Each horizontal line on the upper half of the image is just one of 51 ensemble members; a slightly different version of the same model run.  We’re looking at 24 hour rain/snow totals.  Time goes from today on the left side to two weeks from now on the right side.  The bottom section is just the average of all of those ensembles.  Two key points here  1) The first decent rain chance isn’t until Friday/Saturday the 15th/16th.  2) Very few members show a rainy pattern and 3) A few produce no rain at all through the 19th/20th.

High pressure is developing east of the Cascades and will strengthen as cool air deepens in the lower elevations over there…

Mark EastWind ColdAir Builds Basin

That cool/dense air can only move through the Cascades in the Gorge if it’s less than 3,000′ thick.  That layer of cool air gets squeezed down much thinner as it moves into Western Oregon.  The wind accelerates as it moves from Cascade Locks to the Troutdale/Camas areas.  This pattern will continue as long as the upper-level ridge sits along the West Coast…through the next 10 days.  So you folks in the western Gorge and eastern metro area have a long period of screaming easterlies ahead…sorry!  This will be what we call a “gap wind” event where the areas downwind from the Gorge get the wind, the yellow areas on the map:

Warnings Gorge and Metro East Wind

Other parts of the metro area stick with mainly light wind.  The strongest wind will at the western “exit region” of the Gorge.

Warnings Gorge and Metro East Wind2

Peak gusts there should generally be in the 60-80 mph range the next few days.  Of course if you’re right on an exposed point (Crown Point), the wind can be even stronger.  This is the setup where you can easily record 100+ mph gusts on the steps at Vista House.  Enjoy, but bring a ski mask and a thick jacket!

Temperatures will be gradually cooling at the lower elevations the next few days (no more 50 degree highs!) while the mountains warm up as the upper-level ridge builds overhead.

On a brighter note, today’s sunset is the earliest of the year…it’ll be 4:27pm for the next 10 days.  By New Year’s Eve we’ll gain 10 minutes of daylight in the evening.  Summer isn’t far away right?

Chief Meteorologist Mark Nelsen


Rare “December Drought” & LOTS of Chilly East Wind On The Way

December 3, 2017

7pm Sunday

We’re drying out this evening and now you can say GOODBYE to the rain for quite a while.  Meteorological Winter (December-February) is going to start out very dry.  It’s possible we won’t see any significant rain for more than 10 days!

The typical westerly jet stream (our storm machine) we see in winter is heading much farther north this week and beyond.  A strong upper-level ridge of high pressure is developing along the west coast of North America and it’s going to stick around for an unusually long period of time.    You can see on the forecast chart from the ECMWF model for this coming Wednesday:

The lines are the actual model ensemble average (51 different runs of the same model) and the colors represent deviation from normal for this time of year.  Huge above average heights all along the West Coast, and well below normal in the Eastern USA.  Then let’s move ahead to ONE WEEK LATER…same thing!  If this pans out, expect dry conditions all across the far western USA for the next 10 days.  All models are in good agreement with this scenario as well.

Looking farther ahead, here’s the view at Day #15, Monday the 18th.

This is the beginning of the first week of Christmas Vacation for lots of kids (some like mine don’t start that 1st week until Friday the 22nd).  The ridge is still there, but a bit weaker, and more likely we’d see some mild westerly flow breaking through at times.  All global models show this same scenario through the next two weeks.  Either a dry & warm upper-level ridge over us or wet at times & warm (this last map).  NONE show a cold and wet or cold and dry pattern in the mountains.  Let’s cover the main effects from this upcoming weather pattern:

 

INVERSIONS

Notice I said it’s a warm UPPER-LEVEL ridge.  At our latitude in winter when it warms up overhead with strong high pressure, it won’t be warm down in the valleys where most of us live.  A strong inversion will form under the warm air in the mountains; that starts Tuesday.  That’s because the long nights and very weak daytime sunshine doesn’t allow the surface layer of cold nighttime air to warm up.  Assuming these stagnant conditions continue, it will actually cool a bit over a period of days or a week.  That’s why you’ll notice my current 7 Day forecast is warmest on Tuesday (when the first east wind arrives), then turns cooler later this week and into next weekend.  East of the Cascades a cool pool of air will form below about 3-4,000′ in the Columbia Basin.  That pool of cold air is heavy and dense.  It’ll be trapped over there except for one spot it can move at sea-level…through the Columbia River Gorge.  Yes, we have unending days of…

EAST WIND

It’s time!  Every winter those of you at the west end of the Gorge and east Portland metro area suffer through long periods of cold east wind.  That begins Tuesday afternoon and continues until further notice.  I can’t tell you when it will stop this time around…sometime the following week maybe?  At first you can expect temperatures in the 40s out there (Tuesday), but then as the cold air gets established east of the Cascades the airmass will cool.  By next weekend you’ll be only in the 30s with east wind gusts in the 60-80 mph range anytime beyond Wednesday.  It’s going to be a long haul folks!  Tie everything down.  Rumor says Wednesday could be a “Vista House Day” for the weather geeks.  But…there is one huge benefit to that dry east wind…

SUNSHINE

Yep, we’ve got day after day of sunshine coming.  In the metro area we’ll start with areas of fog Tuesday, but Wednesday and beyond it’ll be too dry to support fog for us.  This is the cool/crisp weather I personally prefer in December IF we can’t get any good storms.  If you live from Salem south in the valley it’s possible your fog lingers all day Tuesday and part of the day Wednesday, it depends on how much drier air works into the valley midweek.

TIME TO WRAP PIPES?

I don’t think you need to do it although why not do it now for the season and be done with it?  In calm areas this week I could see low temperatures drop into the 22-26 degree range (after Wednesday).  Windy areas may not drop to freezing at all.  Those temperatures generally aren’t cold enough to cause big issues, but again, you could just get it done for the season.

CASCADE SKIING

We are very lucky some snow showed up this week, because I don’t see a pattern that brings snow to the ski resorts in the next 10 days.  Timberline & Meadows are open, with 2.5-3 foot bases.  Good enough with modern grooming techniques and short sunny days around 45-55 degrees won’t melt much but that snowpack will become a little…er…consolidated (an icy brick).  Again, groomed runs should be just fine though.   Hoodoo, Skibowl, & Willamette Pass all need more snow to open.  Hopefully some surprise can show up near the start of Christmas Break.

Is this a rare event?  Yes and no.  I’ve gone back and looked over the records.  Let’s assume we go 10 days without rain (a relatively big assumption at this point).  That has only happened in 7 Decembers out of around 80 years of records at PDX.  We had 11 consecutive dry days in 2009, and 14 in 2005 and 12 in 1989.  All 3 were followed by great skiing the 2nd part of winter.  It also happened in 1993 and 1980, those two weren’t very good snow seasons in the Cascades.

Enjoy the next week!  Chief Meteorologist Mark Nelsen

 


Fresh Mountain Snow and a Very Dry December Start

November 30, 2017

10pm Thursday

Today was a gray day but only around .10″ fell in much of the metro area…a classic “soggy” but not “soaking” Pacific Northwest day.  The month ends in just two hours;  it was a slightly wetter than average November in Portland.

Mark November Rain

The first day of December (tomorrow) looks dry as we wait for a weakening cold front to move inland during the evening.  Another chance to hang your Christmas lights and stay dry.   For you skiers/snowboarders this is the plan for tomorrow and the weekend:

Snow Report2

There is only one wet day in our 7 Day Forecast this evening and that would be Saturday.  That’s because next week a new weather pattern takes hold.  It’s a pattern we never saw last winter;  a big “blocking” ridge of high pressure parked over the west coast of North America for many days, possibly well beyond a week.  For comparison, the last time we saw 7 consecutive dry days in December was 4 years ago.  Back in December 2011 we went 9 consecutive days without rain so it’s a rare event but it DOES happen.  Take a look at the upper-level map (500 millibars) for Tuesday.

gfs_tuesday

You see the big ridge developing along the West Coast and a very cold trough pushing cold air down over the Great Lakes.  Next week I’m sure the national weather story will be winter arriving in the eastern half of the country.

In this pattern we’ll see surface high pressure set up east of the Cascades.  That will push a strong easterly wind through the Columbia River Gorge.  Tuesday is the beginning of that setup and it’s possible that east wind will continue for at least week!  In December an east wind is cold as the valleys cool off and stay chilly under wintertime inversions.  The Cascades will turn quite warm next week, likely well into the 40s or even 50s at the ski resorts.  But blue sky and clear/cold nights will keep snow melt to a minimum.

That upper-level ridge sticks around on ALL models through the next two weeks.  Check out the GEM (Canadian) ensemble average for Thursday the 14th:

gem_thursday14th

and the ECMWF ensembles…similar setup with a cold eastern US and mild west (above the inversions):

ecmwf_thurs14th

On a side note, are you are headed out to a tree farm this weekend?  Then Sunday is your day.  It should be mainly (or all) dry.  Saturday looks like a soaker.

Mark Christmas Tree Forecast

Chief Meteorologist Mark Nelsen


No Frost Yet In Portland

November 28, 2017

7pm Tuesday

If you are a gardener like me there’s a decent chance you are staring out the window at a relatively green garden as we head toward December 1st.  I have only had a low temperature of 30 degrees at my home and the banana trees barely look touched by frost and the annuals are rotting, but still alive due to no significant freezing action.  See the lows so far this fall around the metro area.

Mark Low So Far This Winter

The temperature needs to drop down into the upper 20s to really kill off many annuals and very few of us have seen that.  Not on the map is downtown Portland which has only seen a 37 degree temperature.  This is a bit late, but not too unusual.

Mark First Frost Last Few Years

And having a first frost in early December sure is not indicative of the winter to come.  Last year it didn’t happen until December 6th and we know how winter (brrr!) turned out.  It’s more an indication of the weather pattern from Halloween into December.  For frost we need clear nights and a relatively dry airmass to allow temps to drop.  When we have constant rain that doesn’t happen.

But fear not, I expect frost for almost all of us at some point next week.  An east wind pattern is coming much of next week (after Monday).  The result should be widespread freezing for just about all of us west of the Cascades.  Dry offshore flow in December means fog and/or frost west of the Cascades.  It’s likely downtown Portland and a few windy spots in the western Gorge still won’t drop to freezing.

Speaking of dry, the big change is still on for next week.  Bad news for ski areas that are only going to pick up a maximum of 2 feet new snow the next few days, then dry out.

Snow MtHood Outlook

But it’s good news in the lowlands, a chance to hang your Christmas Lights and not get soaked maybe?

Chief Meteorologist Mark Nelsen