Spring Break Is Here!

March 23, 2018

I’ll be on vacation, travelling through parts of the West and spending some time at home over the next week.  Likely no posts, unless I have a spectacular picture to share.

Chief Meteorologist Mark Nelsen

Cold Showers & Foothill Snow Ahead

March 21, 2018

7pm Wednesday

Weather was pretty boring today with light rain moving north out of California.  Thursday and Friday should be more interesting as we get into a typical spring “showers and sunbreaks” pattern.

A strong cold front moves inland tomorrow morning, lowering snow levels quickly from around 5,000′ to 2,000′ by afternoon.  Cool showers follow the front tomorrow night, Friday, & Friday night.  During this time models are advertising 850mb temps (the temp in Celsius around 5,000′) between -5 & -6 over us.  This isn’t a cold enough airmass to get sticking snow to sea level, but vigorous showers should at least get us a mix of rain/snow during the coldest times of day.  I think it’s unlikely we even get sticking snow down to 1,000′ in the metro area; although that could easily happen in the Coast Range and Cascade foothills (nighttime hours).  More likely if you live at/above 1,500′ you’ll get some sticking snow at times.

Snow Spring Headlines

This is not a real wet pattern.  Check out total snowfall through this entire event, forecast by RPM model

RPM Snow Accumulation

Now beyond Friday night we dry out once again with weak ridging in place for much of Oregon’s Spring Break.  Note the ECMWF model ensembles showing a drier pattern beyond Friday.  Many of the individual members give us several days of dry weather next week.


And of course that means temperatures will come back up above normal for the last week of the month.  Pretty good ensemble agreement on that, showing quite a rise after Tuesday.


By the way, with snow coming down into the foothills again, you might wonder how late in the season we’ve seen snow at PDX?  It was on THIS date, March 21s, 2012.


Those records just go back to 1938.  Downtown records go back much farther, but it gets trickier since hail/graupel was added into the “snow column” for observations back then.  I see a 0.3″, 0.1″, & 0.1″ on April 9, 1933, April 14, 1903, & April 14, 1924.  On all of those dates temps didn’t drop below 35 degrees.  On April 7th, 1933 there was a 1.4″ total.  But again, the low was 36!  Must have been deep hail or graupel.

Portland Snow Latest

Chief Meteorologist Mark Nelsen

A Typical March…So Far

March 18, 2018

6pm Sunday

Time is flying by!  We’re already in the 2nd half of March, into the 3rd week of the month.  So what’s ahead?  First a look back; temperatures across the USA so far this month have been cool in the West/East and warm in the middle.  Here in the metro area we’re right at the average temperature so far.


Precipitation has been lighter than average again this month in most of NW Oregon and SW Washington.


We had one brief “wind storm” on the 8th, otherwise nothing real significant has occurred in our area during this first month of Spring.  We haven’t seen a lot of new snow in the Cascades.  But near average temperatures and occasional light snowfall have kept the snowpack on the ground from melting.  Note it’s still quite a low snowpack year with very little time left to catch up now.  Only the NE mountains and Mt. Hood area are reasonably close to normal.

Snowpack Oregon Plus Facts

The next two days look dry as most action heads into SW Oregon and California.  But later this week a cold upper-level low settles in just offshore.  That gives ALL of the West Coast a nice soaking.  Note the hefty totals even down into Southern California; this is a forecast from the ECMWF model for the next 7 days:

ECMWF Precipitation Accumulation

This also means Wednesday through next weekend will feature lowering snow levels with lots of cold lowland showers.  Considering it’s late March, most likely we’ll get some sort of hail/thunder action with the showers at some point between Thursday and Sunday.  We’re overdue for a funnel cloud pic too!

ECMWF Snow Level From 850mb Temps LONG TERM

Notice the sticking snow level may go below 2,000′ at times.  That’s why your weather app may be showing snowflakes mixed in Friday/Saturday.

Can we get sticking snow this late in the year in the lowlands?  YES!  It’s extremely rare but it does happen.  The latest measurable snow at either the Portland Airport or Portland NWS forecast office (the past 80 years) fell on March 21, 2012.   0.5″ was recorded that night as a steady/heavy & wet snow fell throughout the Willamette Valley.  It was only 1-2 days away from Spring Break, but it didn’t feel like it.  The pic is from a viewer


I don’t see that coming later this week, but those of you in the hills might see snowflakes mixed in at times.

The ECMWF model shows rain backing off AFTER this coming weekend.  Note the drop off in precipitation intensity around the 26th-27th.


The blue lines in the bottom section are the ensemble average, and each horizontal line in the top section is one of the ensemble members.  So there may yet be hope for some dry weather part way into Spring Break…we’ll see.

Enjoy the next two mainly dry days!

Chief Meteorologist Mark Nelsen

Warm Spell Ends Tonight

March 12, 2018

7pm Monday

Now THAT was a nice early spring warm spell wasn’t it?  Check out the high temperatures today; several stations are likely to tie or exceed records for the day (Salem and some coastal stations)

Todays Observed Highs OrWa 2017

Portland didn’t quite make it to 70, most likely due to a little TOO much easterly wind.  Notice the coolest spot in the metro area was Troutdale; well exposed to the gusty east wind all day long.

PDX Observed High Today

I now owe Brian MacMillan an iced coffee tomorrow afternoon…I was going for 70.

Even if today is the warmest day of March (a possibility), it’ll be higher than last year.  In March 2017 we didn’t even get above 61 degrees!

March Warmest Temp

Notice when we get above 70 it is typically in the latter half of the month.

We’re headed back to “reality” the next 5-7 days, which means highs in the 50s and occasional showers.  An upper-level low will linger along the West Coast with most energy headed into California.  In fact rain will be significantly heavier in California than the Pacific Northwest.  The result should be a mix of clouds, sun, and occasional light showers Wednesday through the weekend.  But I don’t see an unusually wet weather pattern.

So far this March I’ve been surprised we haven’t seen a pattern that would bring snow down into relatively low elevations; typical in late February/March in La Nina winters.  The pattern for the next week does not look especially cool either, with a snow level between 2,000′ & 4,000′ most of the time.  There is no sign of snow sticking down around 1,500′ or lower…I’m taking my snow tires off after a trip to the mountains Thursday.

Chief Meteorologist Mark Nelsen

Our First Spring “Mini Heat Wave” Sunday & Monday

March 9, 2018

5pm Friday

Today was a pleasant day with just a few sprinkles here and there.  Of course the first week of March has been cool across the West, leftovers of the cool troughing that has lingered over us (or just offshore) since the middle of February.  But get ready for MUCH warmer temperatures the next 3 days.

Spring in our area (March through May) is typically a series of wet or mainly wet days interspersed with a few dry days.  Occasionally from now through May we’ll see a period of temperatures well above average; a spring “heat wave”.  Obviously it isn’t really hot and sure isn’t a real heat wave, but just much warmer than the average high for the date.  This is going to happen Saturday through Monday, especially Sunday-Monday.  Our average high is in the mid 50s in the middle of March, and we’ll be a good 10-15 degrees warmer than that.

Why so warm?  Several reasons:

  1. A cold and deep storm out in the Eastern Pacific will push warm air north along the West Coast

2. Easterly “offshore” wind will be blowing through the Gorge and over the Cascades.  This time it won’t be a cold wind (except mornings east metro and western Gorge).  An offshore wind in March helps warm us up a bit and dries out the airmass nicely.

3. Lots of sunshine.  Saturday will be mainly sunny, although during the late afternoon & evening skies WILL cloud up as a weak disturbance passes overhead.  Sunday should be totally sunny.  Monday starts sunny but skies cloud up in the afternoon.

How warm could we get?  850mb temps (temp in Celsius around 4,000′) peak out around +6 to +8 on Sunday and +8 to +10 on Monday.  Past cases say that if everything is perfect, this setup in March could give us high temperatures in the lower 70s.  But in the case of this weekend I don’t think it’ll be “perfect”.  Lots of clouds arrive midday/afternoon Monday.  So for now we don’t have a 70 in the forecast.  Still, highs between 65-70 are quite deluxe for March 11th/12th!

This won’t last long, we’re headed back to typical cool showers Tuesday and beyond.  Model agreement is good on this.  Check out the sharp change beginning Tuesday on the ECMWF ensemble forecast for Portland


  • Enjoy our first real warm spring weekend!
  • It won’t be totally sunny Saturday & Monday, but you’ll enjoy the warmest temperatures we’ve seen so far this season with ample sunshine.
  • Record highs are unlikely, although Monday will be close.


If you live in the eastern metro area close to the Gorge, or in the western Gorge, the east wind will blow the next 3 days.  Sure, it won’t be a real cold wind, but it’ll feel much cooler than 60-70 degrees.  Peak gusts will likely be in the 30-50 mph range in the Gorge and 20-35 mph range in the east metro area (east of I-205).  This happens during March warm spells, just like in mid-late October when that wind turns a bit cooler.

How many of you remember this early March “heat wave” in 2005?

I’ve never seen anything like it in the first half of March during my entire career.  Day after day with solid sunshine and highs in the low-mid 70s.  Note the 5 consecutive record highs that still stand 13 years later.  This is the ONLY such occurrence in Portland’s daily weather records anytime in the year.

Chief Meteorologist Mark Nelsen



Windiest Day of the “Storm Season” In Portland

March 8, 2018

7:00pm Thursday

What a blustery March day!  The wind was a bit stronger than I expected along the coastline, but reasonable inland.

Peak gust at PDX was 42 mph around 8:30am…I slept through it since I work the late shift.

Wind Peak Gust PDX

Hard to believe but that IS the highest gust we have seen since last April’s windstorm.   This winter has been marked by a real lack of southerly wind events or storms.

Here are some other gusts in the metro area.

Wind Metro Peak Gusts Today

All of the airport locations were between 30 & 50 mph.  That’s a bit stronger than I expected and pretty impressive for a weakening low pressure system moving up the coastline!  I forecast 30-40 mph gusts.  Those numbers only include the southerly wind, not the earlier strong east wind coming out of the Gorge.

Now out on the central Oregon coast it was quite strong.  70 on the Yaquina Bay Bridge and 60-70 within a few coastal towns.

Coast Peak Wind Gusts

Once again this was one of the strongest events of our storm season.

Coming up we have the nicest/warmest weather of our early spring season.  After leftover clouds and maybe a shower tomorrow it appears high pressure will build over the western USA through Monday.  A deep upper-level low develops well offshore and pumps warm air up over us.  This can be a classic setup for very warm spring temperatures.  As of today models are showing 850mb temps up around +7 to +10 both Sunday and Monday.  What happens if we combine that with offshore wind and mainly sunny skies (especially Sunday)?  Past cases tell us we should top out between 67 & 73 degrees in this setup.

An issue for some of us is that the east wind will be blowing all 3 days of our early spring warm spell.  It’s not going to feel as warm in Troutdale, Camas, & into the west end of the Gorge.  Gusts are likely to be in the 30-50mph range out there.  But that’s what happens in March when you get an easterly wind.

Chief Meteorologist Mark Nelsen



Looks & Feels like Spring! Plus Winter 2017-18 Wrap-Up

March 6, 2018

5pm Tuesday

Feels like spring doesn’t it?  Seems appropriate since we’re heading into the 2nd week of March, but that sunshine and afternoon temps near 60 sure felt nice didn’t it?  Before looking forward, let’s look back at this winter we just “endured”.  That’s a bit dramatic, since the only thing we had to endure was some slippery driving Christmas Eve/Day and again the last week of February.  What an easy winter west of the Cascades!  Meteorological winter has now ended and we are in spring…the 3 months between winter and summer.  Calendar makers prefer the late March to late June definition, although that doesn’t follow the sun’s movement or weather very well.


Take a look at temps…a slightly cool December, a “crazy warm” January, then a cool February.  February of course is interesting because the first week or so was very warm, then the next three weeks were cool.  Overall it was a “warm” winter.


Then precipitation…drier than normal

December was well below normal and in February we only saw half of our typical precipitation.  January was just slightly wet.

Note the dry weather covered most of the American West this winter.  The only wet areas were up near the Canadian border, northern Washington/Idaho/Wyoming, and all of Montana.  You can see the result on current snowpack:

Well below normal in Oregon (even with a snowy 2nd half of February).  You can’t make up a whole season of low snowfall in just a couple or three weeks.  But check out those numbers in Eastern Washington, north Idaho, & Montana…big snow there!  This means the Columbia River will have plenty of water this summer, even though most streams in Oregon will be running lower than normal.  Of course if we suddenly turn wetter through May, things could change.


Looking ahead, we’ve got a classic spring mix of wet days and some sunshine and warm temps too.    Take a look at the ECMWF 850mb ensemble temperature for the next 15 days.

You can see the above average temps right now, then another warm period Saturday through Monday.  Then it’s pretty obvious we’ll be entering a cool/wet period by the middle of next week.  There seems to be pretty good agreement with the general pattern, although some disagreement on how quickly a cool trough moves inland early next week.

It appears to me this means we have some nice spring weather coming up again tomorrow, plus this coming weekend.  The ECMWF ensembles show the warmest weather so far this season for Sunday/Monday; highs into the lower 60s.  These numbers are likely underdone, at this point something around 65 or so seems reasonable with offshore flow Sunday/Monday.


You can also see the period of cool/wet weather Tuesday and beyond next week.  So enjoy some mild weather for the next 6 days, classic cool/wet March weather will return!

Chief Meteorologist Mark Nelsen