Snowy In Cascades; 80s Possible Next Week

April 23, 2014

10pm Wednesday…

Quite a dump of snow in the Cascades this afternoon/evening.

Sophie Hood Snow Totals

Looks like a foot or so has fallen so far above about 5,000′, with lighter amounts (just a few inches) down in the passes.  The snow level has zoomed up to around 6,000′ this evening in advance of the cold that moves through late tonight.  I expect another 3-5″ with the showers tomorrow, but no snow back down to the passes until tomorrow night.  This snow is overdue, because we’d typically see about 2′ of snow each April at Government Camp.  Check out the past 6 years up there…those were some cold/snowy Aprils around 2010!


Here in the lowlands a very wet afternoon/evening as expected.  The rain was slow to arrive but now it’s here to stay through sunrise.

Thursday will be a showers and sunbreaks sort of day, same thing for Friday.  One more cold front moves into the Pacific Northwest Saturday and then a warm front drags across Sunday.  Then after ALL THAT, we see some warmer and drier weather.

By Tuesday and Wednesday a strong upper-level ridge will build right along the West Coast in advance of a cold digging upper-level trough in the east Pacific.  The GFS has finally come around to the sharper ridging the ECMWF has been showing.


We haven’t seen this pattern so far this spring with such highly amplified troughs and ridges.  It appears it won’t stick around long, but it will be a dramatic change with offshore flow and sunshine.  The ECMWF continues to be the warmest, showing 850mb temps +14 next Wednesday with easterly wind all the way to the beaches with a thermal trough.  That would give us a high temperature of 80-85 degrees in Portland.  I didn’t go that wild with temps (yet), but the main point is that we’ll likely see our warmest temps so far this spring for the last two days of April.  That’s AFTER 4 more days of wet weather.

Here are the 850mb ensemble charts from the 18z GFS and 12z ECMWF showing the sharp jump in upper-level temps the middle of next week:




Chief Meteorologist Mark Nelsen

6-7 Wet Days Ahead

April 21, 2014

11pm Monday…

The forecast for the next week is pretty clear; wet with cooler than average temperatures for late April.  This has been well-advertised on models and in forecasts, so I got my lawn mowed, burned some debris, and planted a few things that could use a week-long soaking.  Hope you all got anything taken care of that needs to be done outside too!

A chilly upper-level trough is about to move inland this evening.  It’s quite a pocket of chilly air; snow levels should dip down to around 3,000′ by sunrise.  Not a whole lot of moisture left at that time for big Cascade snowfall, but for the first time this month we should solidly white pass highways right at daybreak.

Then we’re into the showers/sunbreaks routine tomorrow as the strong April sunshine heats the ground, contributing to weak instability in the atmosphere.  With such a chilly air mass it’s possible you could see brief hail or thunder at your house if you live inland between the Coast Range and Cascades.

Wednesday and Thursday look WET!  Take a look at our RPM rain accumulation graphic:


Several surges of rain move through along with gusty southerly wind; looks more like early March than late April.  But we’ve been a bit above average so far this month temperature-wise so now it’s time to be a bit cooler (thus an “average”).

What about Cascade snow?  Quite a bit up around 5,000′, not too much below:


The milder than average temps the first part of April have accelerated the normal spring melt below about 5,000′ in the Cascades.  Note the snow water equivalent at 4,800′ Santiam Pass (Hogg Pass SNOTEL):


The solid blue line is this snow season’s SWE, the light blue is average.  You can see the plummeting values the first half of this month.

Up at the lower elevations of Timberline Ski Area at 5400′ the story is a bit better:


With all the snow coming the next week at that elevation we’ll probably see the highest values of the season coming up, a “second peak”.  Interesting that at that site the average does linger at the maximum for a little over a month, then there is a quick fall-off as temperatures warm rapidly in late May.

Enjoy the rain…

There is some hope on the horizon.  Models give us at least some brief ridging about a week from now (NEXT Tuesday/Wednesday).  Take a look at the 850mb chart from the 00z GFS showing temperatures at the 5,000′ elevation returning to normal or a bit above after next Monday.


You can see how the very warm 00z GFS operational run is quite an outlier.  I doubt we’ll be seeing a +17 deg C. temperature on the last day of April.  That would be a high temperature well into the 80s.  But it appears it will be warmer and drier right after our 7 Day forecast ends.  The 12z ECMWF was very warm as well and warmer than most of its ensemble members.  Here is the operational run showing high temps up around 80 at the same time:



Chief Meteorologist Mark Nelsen


Easter Weekend: Wet, then Warm/Dry

April 18, 2014

11pm Friday…

Here’s our latest forecast for Easter Weekend:


quite a change from Saturday to Sunday.   I think Sunday afternoon will be one of those real nice spring afternoons…good enough for a BBQ!

Southerly flow pushes lots of high/mid clouds over us Monday with a shower possible just about anytime.

By Monday night, a chilly upper-level trough is approaching, increasing shower activity.  This leads us into a pretty long spell of cool and showery weather.  A 2nd cold trough settles in late next week and into the last weekend of the month.

Take a look at the 12z ECMWF and 00z GFS ensemble charts, you can see the below average temps through the next 7+ days beyond Tuesday.  Also notice very good agreement through that period too.

tseries_850t_000-384_Portland (1) tseries_850t_000-360_Portland

Better get your lawn mowed either Sunday or Monday!

 Chief Meteorologist Mark Nelsen

Dry Start To April; Make Up Time Next 7 Days

April 16, 2014

11pm Wednesday…

April has been quite dry so far, with less than 1″ rain falling in the past two weeks:


But it looks like that will change tomorrow, and again next week with a few wet weather systems moving through our area.  You can see from the chart below that as of mid-April we are about halfway between the wettest and driest time of the year in any average year; April is one of the 6 driest months…typically.

A nice cold front moves through the region Thursday afternoon, giving us a rainy and breezy day.  Beyond that the Easter Weekend is looking like a mix of wet and dry, with the rain likely arriving sometime Saturday midday or afternoon and then disappearing around daybreak Easter Morning.  Those of you headed to sunrise services outside will PROBABLY stay dry.  The rest of the day looks dry as well.  If so, it’ll be our 3rd dry Easter.  Remember last year?


It was incredible; both days of that weekend were 77 degrees and mostly sunny!  No such weather this year, but once again at least it appears dry.  Next week looks showery and cool to me; we have cool upper level troughs either sitting over the area or swinging through most of the time.  You can see the below average 850mb temps on the 12z ECMWF ensemble chart:


The ensemble average temp drops below average next Monday and stays there for the following week or so.  Interesting that a few members try to warm us up with some ridging NEXT weekend, but just a few.

So…get ready for showers and chilly temps next week!

Chief Meteorologist Mark Nelsen

Lunar Eclipse Tonight

April 14, 2014

5:30pm Monday…

It’s a total lunar eclipse tonight:  First “chunk” starts disappearing out of the moon at 10:59pm, then progressively gets “eaten” up until the entire moon goes nearly black for a little over an hour starting at 12:08pm.  Some have been calling it a “blood moon”, but it’s only expected to be a yellowish-orange due to the lack of dust in the earth’s atmosphere right now.


Here’s the problem, we’ll have a lot of clouds arriving about that time so we may or may not actually see it here west of the Cascades.  For MOST OF US, I think there will be breaks in the cloud cover; at least enough to see it part of the time.  Most likely the clouds will be packing up against the Cascade foothills as we head towards midnight, so those areas on the east side of the Willamette Valley and in the foothills have a smaller chance of seeing the eclipse.  The best chance overall is east of the Cascades, or east of Cascade Locks in the Gorge.  Take a look at our RPM forecast for 1am and you get the idea:


Chief Meteorologist Mark Nelsen

Beautiful April Weather Continues

April 10, 2014

10pm Thursday…

Another sunny and warm day today…66 here in Portland for the official high today.  Today was our 5th day in the 60s (or 70s), and it appears we have at least 4 more.  Many years we don’t see a warm and dry stretch that long in the month of April.  Take a look at the sunset this evening!


Photo by Michael Trofimov.  One more picture came in today from Gene Blick, showing a nearly snow-free Lost Lake basin:


As I’ve mentioned a bunch of times during the late winter and early spring, we’ve had unusually low snowpack below about 4,000′.  Luckily the northern Oregon ski areas had enough snow in February and again in later March to prolong the ski season a bit.  Both Mt. Hood Skibowl and Hoodoo Ski Area have their final weekend coming up; both will be closed for the season after Sunday.   Mt. Ashland was never able to open this season for the first time in its history.  Of course higher up on Mt. Bachelor and Mt. Hood the end of the ski season comes later.  Interest sure wanes at the ski areas in April, especially when we have such terrific weather in the lowlands.  I know it really annoys the ski area operators since they always have more snow on the ground in April and May than early on in November when just about everyone tries to get up on the slopes.  Then, this time of year (in a normal year) there is plenty of snow but interest totally drops off.  I have the feeling the reason is that in November/December it’s usually wet and always chilly outside, so why not head up to the snow and enjoy it?  But we have limited warm weather and sunshine around here in the lowlands so when it finally shows up in spring we want to do all the things we couldn’t do in the winter.  Like bicycling, running, hiking, golfing, gardening etc…  Maybe it’s really just the opposite of November; there is pent-up demand to get outside and do things in the lowlands this time of year so snowplay in the mountains seems so…winterlike.

Okay, enough about that.  Let’s move on to the forecast.

No big changes the next 4 days as upper level ridging builds along the coast and then shifts inland Sunday.  When that happens Sunday, we’ll see a “thermal trough” develop along the coastline with easterly wind from the Cascades all the way to the beaches.  That means one very warm day…probably into the 70s out there too!


Of course we’ll be much warmer here in the valleys as well.  I think MOS temperatures (derived from model information) are too cool with high temps right around 70 degrees.   Just as in the winter, I think they are allowing too much cool air down into Eastern Washington and Oregon.  My April temperature chart shows an 850mb temperature around +9 (models agree on this) with strong easterly flow should give us a high temperature between 74-78 degrees.  Up until the 00z GFS, models have been showing a big marine push Monday afternoon as an upper level trough approaches the Northwest.  The 00z GFS splits that trough, prolonging the warm weather and possibly giving us temperatures closer to 80 Monday.  It IS the GFS, so I ignored it and went with the ECMWF for making my 7 Day forecast.

Beyond that, cooler and wetter weather comes back, although I don’t see an unusually cold and wet pattern.  Take a look at the 12z ECMWF ensemble chart, showing temperatures at about 5,000′ over Oregon over the next 10 days:


Notice the long period of near average temperatures after the warm period Sunday-Monday.

Enjoy the sunshine this weekend!  I plan to clean up the last of the ice storm mess (flames!) in my yard from early March, take a long bike ride, and soak in some rays.

Chief Meteorologist Mark Nelsen


75 Degrees Monday! Mild Weather For The Week Ahead

April 7, 2014

We didn’t hit the record, but the high of 75 degrees in Portland today was the warmest since September 19th!


Quite an achievement considering we started with low clouds/fog in some areas this morning and no easterly wind surfacing in the metro area.  There was a light east wind in the Gorge the first half of the day with gusts around 30 mph in the Corbett area.  A big help was the warmer than expected 850mb temp; it was +11.8 degrees over Salem at 5pm.  That easily pushed us into the mid 70s.  In past cases, that same temperature with easterly flow has given us a high temp between 78-82 degrees in April, so it could be even warmer!  Take a look at the maximum temperature each of the last 9 years in the month of April here in Portland:


Last year we didn’t see 70s until later in the month, when we had a 4 day stretch.

Tomorrow will be a little cooler, but still very warm.  A weak cold front sweeps across the region tomorrow night, giving us a quick shot of rain.  I expect less than .20″ here in Portland.

Then we get weak ridging through this upcoming weekend.  The ECMWF had a chilly trough swinging by just to our east on Saturday, so it was cooler Friday and Saturday.  I ignored that since its ensemble members didn’t support that idea.  Either solution is dry, so it appears we have very little rain in the next 7 days.

Enjoy the mild and mainly dry weather the next few days!  Our 7 day forecast is real pleasant for early-mid April:

7 Day

Models show temperatures near or maybe a little above average in the next 10-15 days.  I sure don’t see a long cool/wet period;  more likely just typical warm, then cooler weather periods.  You can see this on the 850mb temp chart from the 12z ECMWF and the new 00z GFS:





Chief Meteorologist Mark Nelsen



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