A Chilly & Windy March Weekend

February 28, 2014

The first weekend of March is here!  Hard to believe, but meteorologically we’re heading into spring now.  Of course this weekend will feel more like winter than spring, especially in the Gorge and east of the Cascades.  Here are my latest thoughts on this weekend:




Basically I still think the WRF-GFS and NAM are far too cold.  We’ll know by sunrise.  The WRF-GFS says we’ll be about 36 at sunrise and down to 30 by noon!  Anyone with experience around here knows that’s extremely unlikely on March 1st under our current weather pattern.    The 12z ECMWF was a little cool for me to totally say NO SNOW here in the metro area, but I think that even these “warmer” models are a little too chilly.  Notice this shows temps just barely above freezing late Saturday night and early Sunday morning, then southerly flow takes over and we warm up.  All models agree on the rapid warmup from midday Sunday through Sunday night, so at least that part of the forecast is easy.  By the way I really like the mild temps next week; it’s going to feel like (very) early spring.



As for that WRF-GFS; very strange.  Note that this evening’s run still tries to drop up to 2″ across the “east wind zone” of the metro area by early Sunday morning:


But at the same time the sounding shows temps well above freezing during the night around 2,000!


What???  Another reason to ignore it this time around.

The National Weather Service does have a Winter Storm Watch out for the entire Columbia River Gorge (and the valleys around it) for late Saturday through Sunday.  Seems like a good call assuming the moisture shows up.  Not sure if we’ll actually see it cold enough for any big issues on I-84.  It may just be during the night Saturday night through early Sunday.  We’ll see.  This all hinges on how much cold air actually makes it south into the Gorge.  I see the WRF-GFS claims it’ll be 20-25 degrees all day tomorrow at Hood River and The Dalles.  If models are off on the intensity of cold air by 10 degrees then we’ll be out of it in the Gorge by Sunday afternoon.

Stay warm this weekend!

Chief Meteorologist Mark Nelsen

RIP Vista House Anemometer

February 28, 2014

I drove down to Crown Point on the way to work to see what happened to the wind gauge.  Here you go:


A little hard to see (click for a larger pic), but it appears the whole arm and cup assembly either bent or partially broke off.  Now it’s wrapped around the gutter drainage pipe.  Notice the wind direction vane behind the pipe!

Poor little guy, but he made it through two and a half winters in that spot.  Not bad considering you can buy a replacement for just $110!  We’ll see if we can get it on a stronger arm/mast.

Chief Meteorologist Mark Nelsen

Warm Friday, Then March Starts Chilly!

February 27, 2014

I didn’t take a long vacation, just 5-6 days, but apparently there was some excitement while I was gone.  Models (mainly the GFS and for about 2 days) showed a big arctic blast for the first weekend of March.  But now we’re back to reality and I’m working again.  Here are a few highlights:

1. Friday looks great!  Offshore flow on the last day of February with at least partly cloudy skies means 50s and maybe even a few places west of the Cascades around 60.

2. Colder east wind starts blowing tomorrow night and continues through at least Sunday morning.  It’s going to be colder and it’ll FEEL a lot colder than Friday.

3.  IF we get some sort of frozen precipitation west of the Cascades this weekend (snow, sleet, or freezing rain), it will only be cold enough from late Saturday evening through Sunday morning.  Keep in mind that it’s extremely rare to get freezing rain in March in Portland.  In fact I haven’t seen it this late in the season in my 22 years of forecasting in Portland.

4.   If you live at the Coast, or south of the metro area (Wilsonville south to Eugene), forget about anything frozen…too mild.

5.  If you live in the Gorge, snow or freezing rain could linger until Monday morning.  This might be a rare early March ice storm there.  I’ve only seen freezing rain once in 22 years of forecasting here in the Columbia River Gorge.

6.  My gut feeling?  Our forecast models are likely overplaying the cold air that will come down from the north tomorrow night and Saturday and the metro area won’t see anything frozen.  Also I feel at this time that it won’t be a “major” snow/ice event in the Gorge, but just unusually late in the season.

I’ve looked at all the 00z models this evening.  And after several poor performances by the GFS and WRF-GFS the past few months, I finally broke down today and decided to try the ECMWF products over at WeatherBELL.  Quite a bit more detail on those than I get from my data provider.  I think it’ll be worth the $180/year…especially if I can get the boss to cover that!  Anyway, the ECMWF never went as crazy with the cold air to start with since it showed the upper level low sliding down through Western Canada, then retrograding out to the west as westerly flow returned back over us.    Once again, it just does a better job in general than the GFS and apparently that disparity is about to become even more pronounced.  Cliff Mass had an excellent blog post this week pointing out the disappointing developments in numerical weather modeling.  Basically the ECMWF is going to be getting a resolution increase, thus the GFS will be left even farther behind with no sign of improvement here in the USA.

Tomorrow looks excellent with offshore flow picking up during the day, but no significant advection of cold air from the northeast yet.  Hard to believe it’s the last day of February, but mild offshore flow and mostly sunny skies should push us well into the 50s.  Assuming cloud cover doesn’t thicken too quickly, some spots will get up around 60.

Then tomorrow night and Saturday models say the cold air from the big arctic high over Alberta surges south into Eastern Washington and is drawn into the Columbia River Gorge.  This is where I think models are being too aggressive with the cold air.  There’s very little upper-level support.  Consider that in each arctic air event this winter (all two), models overdid the initial push of cold air, and they were too fast both times as well.    Take a look at the WRF-GFS for 7am Saturday.  I find it extremely hard to believe that it’ll be 13 degrees at 2,000′ at the eastern end of the Columbia River Gorge in this setup.  That same model shows a HIGH of 34 Saturday…no, it’s unlikely that we’ll even get BELOW 34 Saturday morning since the wind will probably pick up during the night.


I did notice the 00z WRF-GFS is slightly warmer than the 12z GFS from earlier today; only a couple of degrees, but it’s headed in the right direction.  Our RPM is especially uneventful for the whole weekend.  Note the high of 42 Saturday and mid-upper 40s late Sunday as the milder southerly wind kicks in.  Also notice how it’s pretty much dry through Sunday afternoon.  But, this model has been a star performer so far this winter:


As a result, my 7 Day forecast didn’t go as cold as some models would suggest; but similar to the ECMWF, showing temps hovering within a few degrees of 40 from late Friday night through Saturday afternoon.  Then Saturday night is our chance for snow or freezing rain assuming more moisture shows up than either the WRF-GFS, GFS, or RPM show.  The ECMWF was much juicier from later Saturday through early Sunday and I’m trusting that one more.

By Sunday afternoon the cold air is disappearing as a weak southerly flow starts in the valley.  And Monday we should actually have a breezy south wind; pushing temps well into the 40s.  This is assuming models ARE too aggressive with the cold to start with.

We’ll see tomorrow if models back off on the cold air a bit further or not; another good 24 hours of model riding!

By the way, would you people prodding each other in the comments a couple of days ago knock it off?  Again…40+ year old guys acting like its middle school.  Amazing.

Chief Meteorologist Mark Nelsen

Vacation Time: Vista House Sensor Dies

February 25, 2014

As mentioned in the post last Thursday, I’m on vacation for a week. But I was just checking out the strong wind in the Gorge. Looks like Corbett gusted to 77 mph early today. So I went to the Vista House sensor. It may have physically broken, or is beating itself against the side of the building. It was gusting in the 70-80 mph range and then has mostly gone dead with just occasional gusts. It lived a good life though. Made it through 3 winters! That’s all. I’ll be back online Thursday. One more day of this


A Last Gasp Of Winter? A Snowy Gorge Likely Monday

February 20, 2014

10pm Thursday…

The next 3 days look very nice weatherwise…partly cloudy skies with just a few sprinkles likely on Friday morning.  There will be rain and snow to our north in much of Washington later Saturday and Sunday, but at this point it appears it’ll all stay to our north.

I had a grand plan for this evening since I’ll be on vacation tomorrow through Wednesday.  I was hoping to put the chance of snow/freezing rain in the Gorge and north central Oregon to rest this evening for the first part of next week and then (see previous post) tell the viewers that winter is pretty much wrapped up in the lowlands of Western Oregon/Washington.  But then the 00z GFS came in even a little colder with some “backdoor arctic seepage” Monday and Tuesday.  Ewww…what is that?  It’s cold air that gradually works its way down from Canada, into Eastern Washington, and then through the Columbia River Gorge and into the Portland metro area. That’s as opposed to an arctic blast that brings cold air across the entire region.

As a result there will be no “Winter is Over” proclamation for now.

Our RPM clearly shows rain approaching the coast quickly on Sunday evening, as does the GFS and ECMWF.  At the same time pressures are lowering to our west with an approaching “warm front like”  system, high pressure and cold air is building east of the mountains.  The result is a very strong east wind (8-10 millibars) through the Gorge.  850mb temps are below zero eastside and just a few degrees above zero westside.  It will be a very shallow cold air mass west of the Cascades as a result.  My current forecast even assumes the GFS/WRF-GFS is bringing down too much cold air eastside.  In fact take a look at the snow forecast from the WRF from late Sunday night through early Tuesday morning:


I think the snow west of the Cascades probably won’t happen as I mentioned, but look at the healthy totals in the Gorge!  A good 6-10″ from Bonneville to Hood River!  And snow all the way down into central Oregon too as the cold air pushes south.  You can also see with the east wind the WRF is trying to create the same heavier snow up against the Coast Range and in Columbia county that we’ve seen a couple of times this winter.   Again, I’m assuming it’s bringing too much cold air down at that time.  Note the 2 day rain totals from the same model:


IF the air is cold enough in the Gorge, which it appears to be, that’s plenty to support those snow totals.  The reason is that moist and mild westerly flow is undercutting the upper level ridge over us.

So it boils down to this:

MONDAY IN METRO AREA:  A cold and rainy day in the Portland metro area, instead of high temps around 50 or so on Sunday, temps will hover in the upper 30s to around 40 all day.  A gusty east wind 20-30 mph will make it feel colder!  Could see freezing rain as close as Corbett and the hills above Washougal in the Gorge.

TUESDAY IN METRO AREA:  Still chilly and breezy eastside.  Showers taper off, temps creep into the mid 40s.

MONDAY/TUESDAY  IN THE GORGE:  Some sort of snowfall is looking more likely this evening.  Depending on how cold the air mass is, could be just 2-3″ or if it’s as cold as these models show and with plenty of moisture, could be two days of snow with 6-10″ with freezing rain at the western end.  Extremely slow warmup Tuesday/Wednesday with cold easterly flow continuing.

Now keep in mind if models warm Monday/Tuesday significantly, none of this will happen.  Keep on top of the latest forecasts!  And the 00z ECMWF was significantly drier than the GFS.  The 00z GEM would be just barely cold enough for that snow too.  So still up in the air for sure.  Maybe LIKELY is too strong of a word.  We’ll see.

Chief Meteorologist Mark Nelsen

Long Range Outlook

February 20, 2014

Just checked out all the maps/models and made the 7 Day forecast.  Not a whole lot going on the next few days.  Friday should be dry!

It appears some sort of upper level ridging is going to be near/along the West Coast for the next 10 days or so.  This time it won’t be totally dry though because it doesn’t appear to be a big blocking ridge that shunts storms well away from our area.  Note the ECMWF ensemble forecast of upper level heights for this coming Tuesday.


You see the above average heights over us.  Then by next Friday a nice cold trough runs right into California…good news for  them!


Beyond that, ridging builds along the coast again during the first full week in March.  Here’s one week later on March 7th:


These maps tell me we are done with the stormy weather for now, and it’s on to a more “March-like” pattern with wet periods mixed with drier weather at times.   Not a real warm pattern, but we should see our first 60-65 degree temp at some point between day 7-14.   With a chilly and wet February, one thing we did miss out on was any sort of “false spring” type weather.  In many Februarys we have at least a day or two in the lower 60s…not this year!

Here are the ensemble charts from the 12z ECMWF and 12z GFS, showing no sign of real cold air, but no huge ridges either.  Interesting to note that these would say no “lower Cascades & foothill ” snow in the next two weeks either.  I’m talking the 1,000-2,500′ elevations where some people live west of the Cascades.  This is an area that has seen an unusually low snow total this season.  It’s been arctic air with snow in the lowlands, or good snow higher up in the Cascades.   Almost none of the cold/wet shower pattern with snow levels around 1,000′ to 2,000′ the whole winter.  I’ve only had 7.5″ the whole winter at my home east of Corbett at 1,000′.



And some more maps, the ECMWF monthly run from last night, showing average 500mb heights.  Each map covers a whole week.  You see the ridging, and then by the 4th week just a jumbled mess.





Chief Meteorologist Mark Nelsen

The Big Dump of Snow

February 19, 2014

What a crazy 3 weeks in the Cascades, and it’s topped off by an extremely heavy snowfall this evening.  As of 10pm Timberline has seen 20″ of snow in the past 24 hours!  Mt. Hood Meadows has seen over 100″ of snow this month.  Snow depth is up to 118″ at Meadows and 133″ at Timberline.  That’s getting very close to normal at those elevations.

So what’s the big picture look like?  Take a look at the big jump in percentage of normal snowpack at two sites around Mt. Hood.  The first is the usual snow measuring site below Timberline.  The other is near Mt. Defiance west of Hood River at a lower elevation:


Not so bad eh?  And I see more through tomorrow, and then a bit more Monday & Tuesday before we dry out.

Friday through Sunday looks uneventful in our area as cooler air filters down from the north.  Temperatures will be below normal (52-53 highs are normal).  But then things get interesting Monday.  That’s because all models advertise a cold arctic high dropping down to our east with the cold air just missing us Sunday.  Then as low pressure gets closer to us Monday, strong offshore flow pulls cold air down into the eastern side of Washington and northern Oregon.  Models are forecasting 8-10 millibars easterly gradient through the Gorge on Monday.  Then moisture overruns that cold air.  Sound familiar?  Yes, similar to what we had the first week of February but the atmosphere is 10-15 degrees warmer and the cold air doesn’t spill south into the Willamette Valley.  Tonight’s 00z run of the WRF-GFS is about the 4th in a row to show the same thing, and the ECMWF, with its lower resolution looks about the same.  They all have precipitation in here Monday.  Below is what the WRF-GFS is forecasting for snow.  This HAS backed off substantially the last few runs; at one point it showed many inches right over Portland :


As a result, I think there is a decent chance a snow/ice event is headed for at least the central/eastern Columbia River Gorge.  Could be freezing rain at the west end of the Gorge too.  OR, models may be pulling too much cold air down into the Columbia Basin so it’ll only be marginal even in the Gorge.  Luckily it’s still 5 days away.

Regardless, all models show precipitation and a strong east wind Monday and Tuesday…a chilly last few days of February!

Chief Meteorologist Mark Nelsen