Ice Storm Warning: Lots of Ice Next 18 Hours

January 7, 2017

11:00pm Saturday…

We’re done with the snow part of our storm since warm air has moved in overhead; just as forecast by models.

Wanderer’s Peak at 4,000′ SE of Estacada is above freezing now, and Horse Creek weather station at 3,700′ east of Silverton is up to 37 with a southerly breeze.  So now we’re into the ice storm part of this event.  The NWS has issued an Ice Storm Warning due to this development.

markwarnings_winter-wx-advisory

Freezing rain showers have picked up on radar now and we’re about to get a bunch over the metro area.  Those showers continue tonight as the glazing of ice starts to thicken on trees/powerlines/roads etc…

marksnowovernight

But the heaviest rain (freezing rain) arrives tomorrow morning/midday as a cold front approaches.  At the same time the cold easterly flow will strengthen again from the Gorge.  Expect the cold wind to pour back out over the east side of the metro area again during the day.  This will keep temps below freezing.

marksnowiceimpactstimeline

As mentioned in the previous posting, we expect up to 1/2″ ice accumulation across a good portion of the metro area during the daytime tomorrow.

As the cold front passes overhead tomorrow afternoon that will totally kill the high pressure east of the mountains.  That also “closes our freezer door” west of the Cascades meaning the Gorge east wind ends and temperatures rise through the evening.  The slow thaw will be on tomorrow night and Monday.  I’m ignoring some models that show a breezy south wind up the valley tomorrow evening.  If that were to happen we’d see temperatures pop up to 45 quickly.

Chief Meteorologist Mark Nelsen


3pm: Forecast Changes A Bit

January 7, 2017

Well, there always has to be some sort of twist & turn to the weather drama right?  We’ve got one now.

First, the initial part of this storm has worked out great:  Trace to 2″ snowfall in the metro area.  We’ve seen that, with heaviest totals south and west as expected.  But now the change…

It’s pretty obvious looking at satellite/radar & short-term models that we’re going to see far less precipitation in the next 12 hours than we have been anticipating.

What does that mean?  There may not be much of anything falling out of the sky between 4pm this afternoon and 8am Sunday…mostly likely just scattered light freezing rain showers.  This is very good news and means we may avoid a really bad ice storm and instead just get light accumulations of the glaze ice overnight.

Take a look at the latest HRRR model for 4pm and again at 10pm:

hrrr_4pm

hrr_10pm

There ARE scattered showers around, but just not a lot of precipitation in general.  I still expect streets to further ice up during the night.

Then as the cold front (overhead) approaches mid-morning Sunday, the steady freezing rain picks up.  It may even be heavy at times.  I still expect temperatures to remain below freezing through the daylight hours Sunday.  Here is the precipitation forecast from the ECMWF from 4pm today to 4pm tomorrow, the time in which we expect it to be all freezing rain, it’s estimating about 1/2″, enough to cause plenty of trouble, but definitely not a severe ice storm:

ecmwf_precip_24_portland_7

Here’s our updated forecast for the metro area…notice the lighter ice glazing.  That’s VERY good news!

marksnow_otherareas

Chief Meteorologist Mark Nelsen


Noon Update: Snow Arriving

January 7, 2017

I noticed, like many of you did, that precipitation briefly began as freezing rain or ice pellets in most of the valley and Portland area.  That’s because there is warmer air overhead (above 2,000′), but it was quite dry to begin.  Once that initial precipitation fell, the temperatures cooled below freezing up there and now most of us are back to pure snow.  It’s snowing at a pretty good clip here at home (about to head to work).  Roads are turning snowy/ice in much of the valley too.

sherwood

salem

So the general forecast is still on track…snow to freezing rain this evening.  Here is an updated forecast for all the areas:

PORTLAND/VANCOUVER METRO HIGHLIGHTS

A Winter Storm Warning is in effect

  • I expect a Trace-2″ snow before a changeover to ice pellets and then freezing rain around sunset (4:45pm) “Deepest” snow likely west and south metro, lightest north (Clark Co.) & east
  • Temperatures have likely peaked for today and may drop a degree or two with heavier precip arriving
  • Strong east wind continues central/east metro area.  Gusts 40-50 mph = drifting and blowing snow.
  • Then freezing rain is the precipitation type through Sunday evening.
  • For much of the metro area, this means an ice storm begins this evening and continues through Sunday evening as the cold east wind continues to blow.  Expect 1/2 to 1″ ice accumulation which will bring down trees/limbs/powerlines.
  • I don’t expect temperatures to go above freezing in the metro area until Sunday night.
  • A slow thaw (no real warm south wind) begins after sunset Sunday and continues through midday Monday.  Many roads will still see lots of ice leftover even on Monday AM.

IMPORTANT NOTES FOR THE METRO AREA

  1. All roads will be frozen all today (unless they’ve been treated with gallons of some sort of de-icer) and most of them stay frozen Sunday.  ODOT says they may finally be using salt in specific trouble spots on freeways from what I hear, so it’ll be interesting to see if it’s effective during freezing rain.  By Monday afternoon I think main roads should be back to normal for most parts of the metro area.
  2. Probably still lots of school closures Monday AM

WESTERN VALLEYS FROM LONGVIEW TO EUGENE

The same general plan with snow to freezing rain today.  Parts of the valley could see up to 3″ of snow, but I think Trace-2″ is most likely.  It’ll be lightest to the north around Longview.  Then freezing rain through at least Sunday midday.  Expect up to 3/4″ ice accumulation by midday Sunday.  This could be a damaging ice storm for many of you.  The valley will warm up above freezing probably Sunday evening a bit quicker than here in Portland.  Then the event will finally be over.

OREGON and SW WASHINGTON COAST

Temps will be slow to warm, but this will be a relatively minor event at the coastline compared to valleys.  Temps will eventually go above freezing by this evening.  So expect a Trace to 2″ snow by late afternoon with a wintry mix of ice pellets to freezing rain.  Then just rain well after dark.  The coastline should be all above freezing later tonight through Sunday.

COLUMBIA RIVER GORGE

As always, this area is the biggest problem because it’s the meeting ground of the Pacific moisture and cold eastside temps.  It’s the only place between Canada and California where that happens.  Today’s snow will be accompanied by the usual blizzard-like conditions at the west end due to the strong wind.  By this evening the far west end (Corbett/Washougal) will transition to freezing rain like the rest of the metro area, but the east end stays as snow through midday Sunday in the deeper cold pool.  The wind ends Sunday evening, but I don’t see a warming west wind; your snow isn’t going anywhere afterward for Monday/Tuesday.  Expect a total of 6-10″ at the east end, and a big ice storm again at the west end.  There will be some thawing Monday at the far west end.  A second, even wetter storm arrives later Tuesday and goes into Wednesday as the cold east wind returns.  This could be a real whopper with heavy snow east and snow or freezing rain west end.  Details uncertain on this one 3 days out, but prepare for an extended period of difficult travel in the Gorge this afternoon – Wednesday.

CENTRAL & NE OREGON

More snow…  Expect severe blowing snow and blizzardlike conditions again on I-84 through the Blue Mountains and Ladd Canyon.  Winds are gusting near 70 mph on I-84 right now in Ladd Canyon.  The Grand Ronde and Baker Valleys will be a mess with the blowing snow this evening.  All areas get at least 2″ out of the storm, but many higher mountains will see 6″ or more.

We will likely be on-air much of this afternoon/evening on FOX12 so my time will be a bit limited for the blog.

Don’t forget to keep at least one eye peeled on those outside conditions!

funny_kid_licking_window

Chief Meteorologist Mark Nelsen

 


Strongest Gorge Wind In Several Years

January 7, 2017

9:30am Saturday…

Unusually strong wind is blasting the west end of the Columbia River Gorge this morning.

With approaching low pressure and strong high pressure to the east, the pressure gradient has jumped to the highest we’ve seen it in a least 3 years.  Around 13 millibars from The Dalles to Portland.  I don’t remember the last time I’ve seen it that high.  I’ve never seen it above 14 millibars.  That equates to a damaging wind.  Portland pressure is the bottom line and The Dalles is up top.

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Peak gust at Corbett school was 77 mph this morning, also the highest in several years.

corbettwind

The Vista House wind sensor is a bit beat up this winter, I’ve noticed speeds have been a bit low during several events.  There has been a gust to 83 mph there.  Note these speeds are occurring with temperatures in the upper teens!  Anyone want to go hang out on those Vista House steps and get an accurate reading???  I didn’t think so.

Peak gusts have been in the 40-50 mph range in the far eastern suburbs of Troutdale and Gresham.

The strong (damaging in spots) wind will continue through Sunday afternoon, then go mainly calm Monday and most of Tuesday.

Chief Meteorologist Mark Nelsen