Warmest February on Record: Final Numbers

February 29, 2016

5pm Monday…

February was not only the warmest on record here in Portland, but also warmer than a typical March!  Today’s low of 45 and high of 52 are the final numbers of the month, so now we can calculate the numbers:


A full 5.5 degrees above average!  This JUST BARELY beats February last year for the top spot…by all of .1 degree.


These past two Februarys have been a far cry from the cool and wet February 2014 (with the snow & ice) haven’t they?

March is sure looking wet, at least the first two weeks.  Check out the GFS meteogram…the ECMWF is similar:


Temperatures should be near normal, but then it turns cooler about a week from now as a cold upper-level trough edges closer.  You can also see the shift to cooler on the ECMWF monthly maps from last night.

Week 1 & Week 2 (these next two work weeks)


Then in week 3 & 4 the trough weakens and retreats farther west along with the ridging over us and north.  This would imply spring starts the 2nd half of the month:

For the real geeks, here are the precipitation anomaly maps for the 4 week period showing much drier weather after the 2nd week…we’ll see.

Chief Meteorologist Mark Nelsen

Shrinking Snowpack In Lower Cascades

February 26, 2016

11pm Friday…

Take a look at the change in snowpack in the mountains over the past two months…





Quite a change isn’t it?  What was turning out to be a HUGE year for snowpack (and water supplies) across the region has now turned into a ho-hum snowpack.   Most areas are probably okay for water this coming dry season, but as of now the current snowpack probably won’t help entirely erase the drought in parts of Eastern Oregon.


It’s due to a classic El Nino split jet stream and subtropical ridging along the West Coast.  We’ve been seeing that for the past 8 weeks, since right after the New Year.  This is VERY NORMAL in an El Nino winter…most of the action tends to happen in the first half of the winter.    Due to this, we’ve had very warm weather as detailed in posts over the past few weeks.  Look at the snow depth (in red) and snow water equivalent (blue) at two sites near 4,000′ SE of Multnomah Falls and just east of Trillium Lake so far this year.  You see the snow depth at both peaked in late December, with a 2nd max just a couple weeks ago.  These lower elevations typically peak in the next few weeks even in a normal winter, as a result most likely below the 4,000′ elevation we’ll see the snowpack continue to dwindle in early/mid March with no cold/wet pattern in site.

Luckily for ski areas the few cold/wet systems have arrived just ahead of or during the weekends when most crowds hit (this evening’s rain wasn’t real helpful for night skiing).

As of now there appears to be enough snow to keep even the lower ski areas open until Spring Break (begins 3 weeks from today), unless we get some unusually warm rains.

Looking ahead, it sure does look like March with mild temperatures and occasional rain.  You do see breaks in the rain in the GFS meteogram from tonight’s 00z run:


Enjoy the dry day Saturday and if we get lucky maybe a hail shower or rumble of thunder Sunday afternoon?  Sorry, that’s the most excitement I can find in the weekend forecast.

Chief Meteorologist Mark Nelsen


Warmest So Far Today; But Rains Return

February 25, 2016

11pm Thursday…

What a day!  Felt more like early April with high temperatures up into the low-mid 60s across the metro area


Off the map, Battle Ground hit 71, Roseburg 72, & Forks (WA) made it to 70.  Quite a taste of spring.

That changes somewhat the next few days as rain returns.  Some rain Friday afternoon and then quite a bit more on Sunday.

Models are looking wetter for much of next week; just in time for March!


This winter will go down as the 4th warmest in Portland’s history, at least at the airport.  A mild winter is to be expected in an El Nino year here in the Pacific Northwest.  At least that has turned out well.  But no so much with the precipitation forecast.  IN GENERAL, El Nino years give us normal or drier than normal weather from northern Oregon north into British Columbia.  Meanwhile MOST El Ninos give southern California a soaking…but not this year.  The much anticipated drought-busting winter has been a no-show.  Take a look at rain since January 1st


Those are definitely not the numbers you want to see to end a drought down there.  It seems to me that we’ve been seeing a very persistent subtropical ridge along the West Coast (relative to normal), diverting wet systems farther north than normal.  Basically the whole pattern seems shifted to the north this year.  Just a guess.  The graphic below represents what I’m thinking.  The MOST EL NINOS FOLLOW THIS PATTERN text refers to an earlier part of the scene where the wetter than normal is down in California.


We’ll see how March goes, but California is just about out of time to get the big rains.  There ARE hints on the monthly ECMWF maps from last night though.  Look at the pattern showing lower than normal heights to our south and persistent ridging over/north of us through the next 4 weeks.  This pattern could produce better rainfall for California…we’ll see.

Chief Meteorologist Mark Nelsen

More Warm Weather Facts

February 23, 2016

10pm Tuesday…

Just made this pic for the 10pm newscast:


Two very warm Februarys; and today we “only” hit 59, but some parts of the metro area made it into the lower 60s


Looks like a lot more cloud cover tomorrow, especially west of I-5 as a cold front dies over the coastline.  East of I-5 and over the Cascades quite a bit more sunshine.  Beyond that, Thursday is looking quite warm, we’re forecasting 65 degrees.  We’ll see how that works out.

Chief Meteorologist Mark Nelsen

A Milder & Drier Week

February 22, 2016

The weather is a bit slow this evening, as it has been most of the last 6 weeks.  After some cool and showery days late last week now we’ve dried out.  February here in Portland is running 2nd warmest on record, behind last year:


Notice how warm these past two Februarys have been compared to previous years?  In fact the last “cold” month (relative to normal) WAS 2 years ago…February 2014.  It’s been a long two years of mild to very warm to record-breaking warm weather!  You can see the toll it has taken on our mountain snowpack.  The northern Oregon Cascades are below normal now with the southern/eastern half of the state above normal but nowhere near where it was 6 weeks ago:


Looking ahead, a mild week with upper-level ridging along the West Coast


There was quite a bit of dense fog around this morning, but with a drier atmosphere Tuesday morning the fog shouldn’t be as widespread.  Plus easterly flow has begun overhead and when that happens the fog layer tends to be very thin.

How warm later this week?  Not excessively warm, just 8-12 degrees above normal.  I doubt we get above 65 degrees, but we may exceed the highest we’ve seen so far this month (63).

Showers do return as some weak systems move through the ridge over the weekend, but in general we stay mild through the end of meteorological winter early next week.  Spring begins mild the middle of next week too.  Here are the 4 ECMWF weekly maps, showing 500mb height anomaly among the ensembles.  No changes, quite a consistent forecast over the past 2-3 weeks.  These forecasts are doing much better than back in November when they showed ridging in December…that didn’t work out well…


Chief Meteorologist Mark Nelsen

ECMWF Monthly Run

February 18, 2016

Looks similar to what we’ve been seeing for a few weeks on these maps; higher than normal upper-level heights continue for the foreseeable future in Western Canada.

We are on the edge of that ridging so not a real dry pattern but systems should continue to be mainly weak and we’ll see warmer than normal temperatures as we head into the first couple weeks of March.  Our long slow march through late winter/early spring is here.  Unlikely we’ll see snow below 2,000′ again in this pattern.

The 18z GFS ensemble system supports the general warming pattern starting the middle of next week:


I was just mentioning to Liana this evening that it appears Sunday or Monday morning could be the only chance for a freezing temperature at PDX this month.  By that time we will have only seen one frost in 6 weeks in Portland!  Strange stuff…

Chief Meteorologist Mark Nelsen

Wettest Winter on Record at PDX

February 17, 2016

10pm Wednesday…

We only had one lightning strike today…near Crown Point, but at least we got a rain record out of the evening downpours!  As of 9pm it’s the wettest December-February (meteorological winter) on record at PDX.


As you see, the records go back 78 years.  What a soaker and of course we still have another 12 days to go.  So we’ll go well beyond that record.

Speaking of rain; very good news up in the Willamette River watershed.  The reservoirs are filling right on time this year.


The whole system is at 26% of it’s full “summer level”.  Sounds low right?  But that’s normal because the Army Corps of Engineers keeps reservoirs low in the winter.  Then around February 1st, as peak flood season passes, they start holding back water the last part of winter and capture the spring snowmelt too.  They started a little early at Detroit Lake in mid January; in the past 30 days the level has risen 45 feet!  It took until early April last year to get to this level…big improvement.  And this year we have a bunch of snow in the Cascades so there WILL be a healthy spring melt.  BIG PICTURE:  WATER ACTIVITIES ON THESE RESERVOIRS SHOULD BE IN GOOD SHAPE THIS COMING SUMMER.

Chief Meteorologist Mark Nelsen