A Taste of Summer For Early May

April 30, 2013

It appears that we are headed for an unusually long period of warm and dry weather.   Unusual because it’s rare to have a solid week or more in early May with temps in the 75-85 degree range, and mostly sunny or sunny skies.

The Highlights

  • There is no rain in sight…at least not through the middle of NEXT week.  Every month so far this year has been drier than average, and April ended up a little drier than normal too.
  • Mostly sunny or sunny skies are likely starting tomorrow for at least 6 days!  Maybe longer
  • Temperatures warm dramatically tomorrow, and continue rising through the weekend
  • This weekend will feel like summer; temps should top out in the mid 80s both days


Technical info:

I had 3 days off and during that time it was interesting to see how the maps changed…more of the same progression we’ve seen in the models the past few weeks.  Specifically, an upper-level ridge is forecast to build more directly over the West Coast but then ends up back in its favored position a ways offshore.  This leads to a very warm 7 Day forecast and then we have to back off a bit.   Last Thursday and Friday both the GFS and ECMWF were showing 850mb temps (celsius temp near 5,000′) up around +14 to +17 for tomorrow (Wednesday) afternoon.  Instead it’s going to be around +5 to +7.  That’s a huge change.  In the end (for the rest of this week) it won’t matter to the average person because the ridge is still close enough to give us weak offshore low-level flow and warm sunshine.


So for the next few days we do have the upper level ridge gradually edging closer, thus the warming atmosphere overhead; we go from that +6 or so tomorrow afternoon to +11-+14 Friday-Saturday afternoon.  Very good agreement on all models with that.  Then a slight change.  Models are forecasting a bit of a “Rex Block” Sunday through much of next week.  That tends to be a very stable upper-level pattern with an upper high centered north of an upper-level low to its south.  The orientation of the upper high north of us may give us good offshore flow Saturday through early next week as well.   Notice the 00z WRF-GFS cross-section showing very little low level moisture until next Tuesday-Wednesday too, thus the very sunny 7 Day forecast:


notice the time goes from right to left, so the right side of the chart is Sunday morning and the left side is Wednesday morning.

The ECMWF does go for more of the offshore ridging instead of a rex block setup over us earlier next week so it isn’t quite as warm.  Here’s the 00z GFS ensemble 500mb forecast for NEXT Wednesday:


and the 12z ECMWF map for the same time:



Either way, one thing is certain, our drier than normal spring weather is going to continue.  For you gardeners, it’ll be time to start watering this weekend, especially those new plants you’ve put in.  Enjoy the sunshine!

Chief Meteorologist Mark Nelsen


A Few Maps for Tuesday Afternoon

April 30, 2013

I had the weekend and Monday off for some kid’s events so a bit delinquent on posting.    So I’m back in the saddle and looking carefully at the weather maps/models…I’ll post a few thoughts later.  I have some other office issues and a project I need to get done.

But for now, here are the latest 18z GFS and 12z ECMWF ensemble charts…very warm for early May:





And then the monthly ECMWF maps from Sunday night’s run:




  Chief Meteorologist Mark Nelsen

Episode 30: Snow Pack, Weather Questions and New Promos

April 26, 2013

Fresh podcast just posted this afternoon…enjoy!

Northwest Weather Podcast

This week, the guys talk mountain snow pack and what areas could see drought conditions this summer.

Plus, they’ll answer your weather questions and break down our Cities of the Week!

Mark and Brian will also take you behind the scenes of the new set of weather promos.  Take a look at one of our newest spots.

View original post

First 80 For Some; More Warmth to Come

April 26, 2013

6pm Friday…

Salem hit 81 degrees this Friday afternoon; making it the warmest day so far this spring.  80 degree highs were also recorded at McMinnville and Aurora.


Here in Portland we topped out at 78 degrees, once again the warmest day so far this season.

The decent, dare I say “nice”, forecast for the weekend continues.  Sure, it’ll drop 10-15 degrees from today over the course of the weekend, but it’s a huge improvement over the cool and showery weather we’ve seen each weekend this month.

We might see a sprinkle late Saturday night or early Sunday morning as a weak system drags across the area, but the main chance for rain is 24 hours later.  That will be Sunday night and early Monday morning.

The forecast keeps looking warmer; models today have speeded up the departure of the cool trough early next week.  We are already getting warmer north-northeast flow by Tuesday afternoon if they are correct.

Both the 12z/18z GFS and the 12z ECMWF show 850 mb temps in the +12 to +14 range next Wednesday afternoon and +14 to +16 range Thursday.  That’s with a thermal trough west of the Cascades and easterly low level flow.  According to my chart for April that would give us 80/83 degree highs for PDX Wed/Thur.  The chart for May is warmer:  82/87.  So I stayed a little on the low end going for 80/83 on the 7 Day forecast.

Agreement on models is pretty good through Thursday, then is all over the place.  Note the 12z ECMWF ensemble chart:


I see by the end of next week it’ll either be -5 or +21…extremely low confidence on any one solution.

and the 12z GFS ensemble chart:


same thing, but not as extreme.

Enjoy the (mainly) dry weekend…

Chief Meteorologist Mark Nelsen

Forecast Keeps Getting Warmer; Maybe 80 Friday?

April 24, 2013

We hit 75 in Portland today, a good 7 degree jump from yesterday due to an easterly “offshore” wind flow.  That east wind even made it to some spots on the coast;  Tillamook made it to at least 75 as well and Astoria hit 71.  Very nice for late April!  Here are the metro highs:


Remember last week when we had to back off the 80 degree forecast for today?  Lots of complaints that the forecast is “always” doing that.  Well in the case of this week we’re going back the other way, so the forecast CAN get warmer.  Why?  Models have backed off and slowed down the cold weekend trough approaching and that prolongs our little warm spell.

Upper level heights actually rise (instead of falling) the next two days and temperatures warm in the atmosphere as a result.   The 12z and 18z NAM both show 2-4 degrees surface temp warming total through Friday.  The GFS is similar.  That would put us around 77-80 degrees by Friday.  Maybe I have a cool bias and should have gone with that 80 after all?  Just a couple of days later instead.  The 12z WRF-GFS says we hit 80 Friday here in Portland.

Big picture:

  • Two more days of sunny or mostly sunny skies.  Even Saturday could be mostly sunny
  • Temperatures will reach between 75-80 degrees both afternoons
  • Saturday is looking like a nice day now as the cooler/showery weather is pushed back a day
  • Not much rain Sunday, just much cooler and more cloud cover


The ensemble charts sure say spring!  Warm to cool Sunday/Monday then back to above average.

12z GFS…


12z ECMWF…



Chief Meteorologist Mark Nelsen

Record Lows & A Look Ahead

April 23, 2013

11pm Tuesday…

The chilly and very dry air mass gave tons of weather stations east of the Cascades record lows on Tuesday morning.  Here’s a list from the Pendleton NWS:

STATION                  PREVIOUS        NEW        RECORDS
                          RECORD/YEAR     RECORD     BEGAN

 *JOHN DAY(CITY), OR      20 / 1960       19         1891
 *LA GRANDE(CITY), OR     25 / 1992       25 (TIED)  1887
 *LONG CREEK, OR          18 / 2008       18 (TIED)  1908
 MEACHAM, OR              21 / 2011       20         1929
 *MONUMENT 2, OR          24 / 1992       19         1915
 *MORO, OR                26 / 2011       25         1897
 PENDLETON(AIRPORT), OR   30 / 2011       26         1934
 *PENDLETON(CITY), OR     29 / 2011       26         1889
 *SISTERS, OR             17 / 2002       17 (TIED)  1958
 REDMOND, OR              20 / 1961       18         1941
 THE DALLES, OR           30 / 1972       28         1929
 *GOLDENDALE, WA          24 / 1920       22         1905

Burns was 13 degrees and Baker City was 12, both records for the date.  As you see below, Baker City hasn't seen a 12 degree temp in the 2nd half of April since the airport records began in the early 1940s!


Coming up…for those of you who think the 7 Day forecast never actually improves with time but most likely goes downhill?  Not this time; it appears Thursday and Friday we’ll see temps stay in the mid 70s.  The 00z WRF-GFS even tries to get us close to 80 on Friday…we’ll see.

So we may end up with 5 days of straight sunshine for this workweek!

Here’s the new 00z GFS ensemble chart:


You can still see the chilly showers for the weekend, but HUGE variety of solutions by the time we get to Tuesday.  Anywhere from -4 to +17 at 850mb!  There seems to be a “cold cluster” like the chilly/showery ECMWF, and a cluster showing upper level heights rising dramatically…Roll the dice…

Chief Meteorologist Mark Nelsen

Larch Mtn. Road Snow Update

April 23, 2013

3:30pm Tuesday…

The snow line has retreated in the past two weeks on the west slopes of the Cascades.  I rode my bike up there in the bright sunshine this morning; just perfect with temps in the 50s, 1 vehicle and 1 bicycle passing me in one hour and 30 minutes!

Three weeks ago I ran into solid snow right after the snow gate.  Today I made it almost all the way to the “big corner” (where the road suddenly swings hard to the right in a switchback with a guardrail) with just a few thin patches of snow.  But  there was a solid area of snow just in front of that corner; so basically the road is passable up to 3,000′.  This is where I stopped since I wasn’t in the mood for wet feet again, and this job thing gets in the way of personal afternoon recreation too.



It’s great cycling with no cars beyond the snow gate; sometimes I get really crazy and ride on the wrong side of the road.  I know…real wild.

A perfect day today and we have several more to go.  We just made the fresh 7 Day forecast and you’ll notice it’s a bit warmer Thursday-Friday.  It appears that lowering surface pressure to the north keeps us from getting a strong onshore push those two days, so minimal low clouds and a warm atmosphere continues overhead.  That snow patch in the pic above will definitely be getting smaller.

For tomorrow, the weak offshore flow returns.  Combine that with a little warmer air mass overhead and we should pop temps up 4-7 degrees over today’s highs.  So we stayed with a 75 degree forecast.

Chief Meteorologist Mark Nelsen