Wet Weekend!

January 16, 2015

11pm Friday…

We’ve got a very wet system moving in tonight.  I think 1-2″ rain is likely in the valleys west of the Cascades, not flooding-worthy, but quite a soaker!

A secondary surface low develops west of the Oregon Coast around 4pm tomorrow and deepens about 10 millibars by early Sunday morning making landfall along Vancouver Island.  This is a setup for strong winds at the beaches.  Gusts in the 60+ range are likely late in the evening and early overnight hours.  Gusts 30-40 mph are likely here in the valleys too

MarkWarnings_Wind_Coast_Valleys2 MarkWarnings_Wind_Coast_Valleys

The mountains are going to be assaulted by at least 2-3″ of rain tomorrow and tomorrow night.  Not good, but definitely not enough to dramatically wash away the base totals.  But SATURDAY IS NOT THE DAY TO SKI.  Much better Sunday and Monday as snow levels fall to around 4,000′, then almost down to 3,000′ Monday morning. MarkSnow_MtHoodFcst  Apparently that’s the best we can get this season because we are going right back into upper-level ridging for at least next calendar week.

Long range maps are still hanging onto the ridging in general through the end of the month, although there are quite a few variations on what comes through the ridge precip-wise and how many times it flattens.  Here’s the GFS ensemble 500mb height map for NEXT Sunday:


Then a week later…Saturday the 30th:


The big ridge is gone but weak ridging is still over us with troughing offshore.  Looks a bit wetter then.

The ECMWF (from this morning) is similar but without the cold trough in the eastern Pacific.


GEM (Canadian) is surprisingly similar to the ECMWF:


As I mentioned in a post earlier this week, looks to me like January may go down as a real boring weather month.

Chief Meteorologist Mark Nelsen

Poll: Do You Think It Will Snow In Portland This Winter?

January 14, 2015

It’s been way too long since we’ve done a poll.  How about this…Will it Snow in Portland this Winter?

  • The official observing site is in Parkrose at the NWS Office.
  • They have recorded a TRACE once, but nothing measurable (.1″ or more).
  • November 13th was the Trace.

Here’s a graph showing Portland snowfall for the past 28 winters:


Last winter’s total of 8″ was a combination of early December snow and then again in early February.  In 3 of the past 19 winters we have seen measurable snow in March.  That’s 2006, 2009, & 2012.  It’s far more interesting to me that February has only seen snow 3 of the past 19 years as well.  Historically December and January are generally our “snow months”.

By the way, to make things a bit more fair for the non-weather watcher, I don’t see a snow producing pattern in the next 10 days at least.  No model is showing any hint of “snow action” through the end of the month.

Chief Meteorologist Mark Nelsen

ECMWF Ensemble Maps & Warm Rain Ahead

January 12, 2015

It’s Monday afternoon, which means 4 maps (1 for each week) from the ECMWF ensembles that take us through the first week of February.  Geez, is February just a few weeks away???  They show the 500mb height and anomaly for each of the next 4 weeks.  This is from last night’s run.  Also, more bad news for skiers; Hoodoo has now closed after just under two weeks of skiing there.  And the important MLK weekend coming up appears to be at least a partial washout.  Models have been trending higher and higher with snow levels.  Aim for Monday, although Sunday may not be bad at the higher parts of the open resorts.  I don’t see any snow at Government Camp until next Monday, and even then it may be just a dusting as cooler air arrives.

Week 1…now through Sunday, ridging overhead the next couple of days and then it gets squished by a strong westerly jet approaching the Pacific Northwest.  You can see a strong trough to our west, but it never moves inland.  As a result we get surges of rain Thursday-Sunday in the southwesterly flow.


Week 2…late this Sunday through all next calendar week…Surprise!  The ridging bounces back over us, mainly dry and not much happening.  With the ridge slightly to the west, we get cool easterly wind most likely.  This takes us through the 25th.


Week 3…the ridge retrogrades (moves west an north).  If so, this would be the time when we could get a shot of cold air from the north on the backside of the ridge.  Maybe.  So 2-3 weeks from now we might see some arctic action on the maps to get us all worked up.  This takes us to February 1st.


Week 4…first week of February.  Can’t quite tell what’s going on exactly but the troughing is getting  quite strong across the Eastern Pacific again and it could be turning very wet with this pattern all along the West Coast.


Remember as always that this is just one monthly run of the ECMWF, but it’s annoying that a strong ridge keeps wanting to pop up over/near us for the 3RD WINTER IN A ROW!  No anger there, just annoyed.

Short term, we have east wind picking up tonight through late Wednesday.  Easterly gradient peaks around 8 millibars through the Gorge tomorrow afternoon and night.  That should be enough to clear out any fog that develops overnight here in the metro area.

I’m surprised again at how warm the Thursday-Sunday systems are…much like we’ve seen so far this winter.  850 mb temps between +2 and +7 during the whole period means no snow below 5,000′.   The snow level should move up and down between 5-7,000′ through the weekend.  Right now it appears Saturday could be the worst with a rain out at both ski areas on Mt. Hood.  Wy’East is getting a nice winter coat this year up top, but he’s not looking so good down at the bottom.

Remember the good old days when we could have a week or two of snow levels between 1,000 & 3,000′?  I think it was the winter of 2007-2008 when for two months (late December to late February) I never forecast a snow level HIGHER than 4,000′.  We haven’t seen consistently low snow levels since the winter of 2011-2012.  Yikes…

If you’re looking for a good snowstorm here in Portland, that’s not in the cards unless we get some of that cold air+moisture between weeks 2 & 3.  We still haven’t seen measurable snow so it’ll be interesting to see if we end up with a “zero” winter.  Quite possible after the overachieving 8″ last winter.

Chief Meteorologist Mark Nelsen

Wild Gorge Wind, Ski Areas Close, & A Look Ahead

January 8, 2015

8pm Thursday…

Forget about the fog, wind is the weather story in the metro area this evening!  Easterly pressure gradients have jumped much higher than models forecast, currently approaching 10 millibars from Troutdale to The Dalles.  Combine that with the very shallow inversion over us and the easterly flow of wind is being squeezed down to a very small area at the west end of the Columbia River Gorge.  That means very high wind speeds.  Vista House gusted to 91 mph after 5pm, which is only one mph lower than the highest I’ve seen there the past 3 winters.  It’s safe to say it’s gusting over 110 mph on those special “Steve Pierce/Keely Chalmers”  steps.  Corbett has been gusting around 70 mph too.  It’ll continue all night out there.

Over the past few hours the wind has been spreading farther west across the metro area.  We’ve gone from calm to gusting 25-30 mph on our brand new FOX12 weather sensor on the roof on the west side of town along US 26.  I see gusts 30-35 mph at Sunset Transit Center and I205/Division too.  Winds should peak overnight or tomorrow morning and then gradually drop off all areas the rest of tomorrow through Saturday.

Let’s talk snowpack…the warm temperatures have slowly taken their toll on the snowpack the past 4 days.  As I’ve mentioned in the past, the weak sun angle and short days of January mean even 55 degree days don’t melt much snow up there.  Warm rain is far worse.  Of course 55 degrees in March or April up there will melt the snow more efficiently.  Regardless, the ski areas that have been skiing on just a few Christmas storms have now closed.  Mt. Hood Skibowl announced today that they are suspending lift operations until new snow falls…from their Facebook page:


Willamette Pass and Mt. Ashland ski areas have closed as well.  There is still 33″ and 44″ at Meadows and Timberline.  That along with modern grooming techniques is enough to allow for lots of skiing, but it’s hard to believe we’re sitting here a year later and once again we are in this position (a terrible snowpack).  Right now most of the Cascades only have about 30% of normal snowpack:


Pretty bad eh?  Not quite as bad as last year, but close.

What’s ahead?  Little or no snow in the Cascades for the next week.  But likely a change late next week.  This has been hinted at by models for a few days now.  Notice the ECMWF showing precipitation arriving next Thursday:


Will it be snow or rain in the mountains?  Check out the ECMWF 850mb ensemble chart from this morning’s run:


Consider pass-elevation snow to be right around the “zero” line.  Looking at the chart, that means we get rid of the very warm air overhead and drop to more normal 4,000-5,000′ snow levels during that wet period.  Note that not all ensemble members are in agreement, but in general it looks cool enough to drop some decent snow in the mountains just in time for the MLK 3 day weekend.

Farther ahead?  The monthly run of the ECMWF was last night and here are the 4 weekly charts:





It doesn’t look like the wet pattern starting a week from now sticks around for more than a week.  Notice the following two weeks show ridging just to our north or northwest; similar to what we’ve seen this winter so far.  That last week is interesting in that it doesn’t show any significant ridging nearby.

Chief Meteorologist Mark Nelsen

January Inversion Is Back

January 6, 2015

Hmmm, seems like we’ve done this recently.  That’s right…January we’ve seen some of our strongest east wind and longest foggy periods the past few years.  Here we are again.  The view from our Skyline Camera at 10pm:


I made a gamble in last night’s forecast; that the clouds would linger through the night and then break in the morning, giving us a very warm day.  Instead the clouds broke in the middle of the night and fog developed.  Now what happens in January with no wind and a foggy morning?  Yes, the fog doesn’t go away quickly, if at all.  As a result high temps stayed in the 40s.

Meanwhile the warmest airmass in over a month has arrived above the cool air here in the valleys.  At 10pm it’s warmer at Timberline (52) than New Orleans, Houston, & Pensacola!  A bit lower, on the west slopes of the Cascades and in Coast Range, temperatures soared into the 60s.  MarkInversion_70s  Tomorrow we may even see a 70 in a spot or two.

What about the fog?  If you live south of Tualatin I think it’s unlikely you see any sun the next 3 days.  Yes, that means in Salem it’ll likely be gloomy through the end of the workweek.  Increasing easterly wind out of the Gorge is going to clear out most of the metro area by tomorrow afternoon though.  That east wind will reach “winter-strength” (gusts 60-70 in Gorge and 30-40 east metro) Thursday and may clear out skies all the way down to Woodburn or so.  If you are lucky.

Enjoy the sun at the higher elevations and take some Vitamin D pills if you live in the Valley the next few days…

Chief Meteorologist Mark Nelsen

ECMWF Weekly Maps

January 5, 2015

It’s Monday afternoon, which means 4 maps (1 for each week) from the ECMWF ensembles.  They show the 500mb height and anomaly for each of the next 4 weeks.

Week 1, we already know a big ridge is over us for the next 7 days.  No surprise here


Week 2, a change, some wet weather systems and a bit of a stormier pattern.  Could end up being on the warm side though…maybe.  Not a pattern that would produce much snow below 3,000′.  But this could give us some big dumps for the ski areas just in time for MLK weekend around the 18th.


Week 3, more action farther south into California, or what you see could be an average of several lows moving by to the south.  Looks like early December’s pattern with ridging developing to our north again while California gets soaked.


Week 4 looks similar to what we have right now.  This would say ridging returns at the end of January and early February.


Always remember, this is one run from the ECMWF model.  But always fun to look ahead, and also compare with the last two monthly runs.

Chief Meteorologist Mark Nelsen

Mild 1st Half of January

January 5, 2015

We are in for a very mild, and drier than normal first half of January.  If you live below 4,000′ in or west of the Cascades snow is not going to happen the next 10-15 days.  Upper-level ridging wants to hang on, just like last winter.  Actually this entire winter has seen the warmer/ridging pattern, minus a week or so around Christmas Break.  Check out the ECMWF 850mb ensemble chart.  Time goes from left to right, the zero line means 32 degree temps around 4-5,000′.  Note most of the time it’s above freezing up at Government Camp’s elevation through mid-month.  The middle of this week it’ll get up around 50 up there.  Luckily snow doesn’t melt much with the short days and weak sunshine in January even with the warm temps.  It’s the warm rain that does it.  Also note not a single ensemble member says snow levels will get even close to the valley.  Note to Weather Geeks:  Nothing interesting is happening this first half of the month, continue with your non-weather lives.  We’ve sure had some boring Januarys the past few years.


geez, the 12z GFS chart is even a bit worse for the same period:


It implies some mountain snow in time for MLK weekend…ski areas will definitely need it by then!  Of course that’s almost 2 weeks away so that could change for better, or worse.

Chief Meteorologist Mark Nelsen