Easter Weekend: Enjoy!

March 29, 2013

Sunday AM Update:

Saturday’s high of 77 in Portland was our warmest March day since 1994!  And quite close to the warmest March day ever (80).  Enjoy your Easter Sunday!

Friday Evening…

Here’s the latest forecast…we will likely tie or break a record high tomorrow and be quite close to a record Sunday.  The records at PDX are 74 tomorrow and 71 Sunday.  Luckily models are backing off on bringing much cloud cover up into northern Oregon for Sunday afternoon.

 March will “go out like a lamb” won’t it Sunday?


I considered turning off comments for the weekend to force us all outside, but decided against a “nanny-blog” solution.  Plus, from today’s (lack of) activity on the comments, I can tell that won’t be a problem.

I will however be disappearing from the online world this weekend though!

Chief Meteorologist Mark Nelsen

A Very Dry March

March 28, 2013

It appears our last decent chance for rain this month has passed now.  Other than a sprinkle tomorrow (very unlikely) or an unexpected northward move of Sunday’s rain into our area, we’re going to be left with 1.46″ rain for the month.  Wow, and we had only about that much in February too!  Really weird if you think about it. 

So how does that rank?  In the spirit of the season…bring on the bunnies!


It’ll likely be the 3rd driest, behind two drier ones in the 60s.  The airport records go back to around 1940.  It hasn’t been exceptionally warm, but we’ve just continued to see very weak weather systems.  I think we’ve had one good rainy/windy storm in a month or so.  That’s it.  A collection of weak systems and occasional upper-level ridging meant more sunshine than normal and much drier than average.

March is going to go out with a “warm weather bang” this weekend.  We raised the forecast temperatures for tomorrow and Saturday on our 7 Day forecast this afternoon/evening.  Today we hit 67 in Portland with partly cloudy skies, no offshore flow and a +3.4 degree temp at 850mb (5,000′) .  850mb temps rise about 10-11 degrees fahrenheit from there by Saturday afternoon.   No, I don’t think surface temps will jump 10 degrees, but it’ll be close.  Previous cases of sunshine, light east wind, and 850mb temps of +10 in March have given us 72-76 degree highs here in Portland.  So I think 74 is a good number for that day.  That would also tie the record high for the date.

Sunday is a tough call temp-wise.  Models are insistent on keeping all cloud cover and rain from Eugene south into SW Oregon; I’m not too worried about that.  We do start with east wind and then go calm in the afternoon here in the metro area.  Usually those conditions keep the high temperature about the same as the east wind day (Saturday) even though the atmosphere is a little cooler up above (+7 to +8).  I’m sticking with 70, but assuming it remains sunny we could be just as warm Sunday.

I clouded up Monday and Tuesday a bit more due to some sort of weak marine push coming in from the SW Sunday night.  Well back down into the 60s.  I’m going 65 but it could easily be “only” 60 or even lower if low clouds linger.

If you plan on travelling this weekend, keep in mind the weather system in California will be sending clouds and rain showers as far north as Florence, Eugene, & Bend during the day Sunday.  It wont be a beautiful Easter Sunday in SW Oregon.

Chief Meteorologist Mark Nelsen

A Bunch of Maps

March 28, 2013

Here you go, a bunch of maps to peruse.  Big picture = mild and dry or mild and more dry than wet the next week or so.  All ensembles are above average (wow, we haven’t said that much during spring the last few years) through about the 5th-6th of April.  Models also try to raise heights above average again about 12-15 days from now.

Here are the latest two ensemble charts:

tseries_850t_000-360_Portland tseries_850t_000-384_Portland

And last night’s run of the ECMWF  out to one month.  Same idea, then weakening ridging by mid-month and maybe some troughing late month.





Rainbow Pics

March 27, 2013

I think we received about 10 viewer pics showing rainbows this evening.  This one is my favorite from Darrick Williams in Salem, click on the image for a larger view:


Thunderstorms Popping Up Westside

March 27, 2013


Looks like 3 strikes just north of Albany in the past 20 minutes with a thunderstorm right over Turner, headed towards Aumsville right now.


Two other showers looking pretty intense may be about to spit out some strikes/rumbles around Newberg/Sherwood and Molalla/Colton.  All storms are headed north-northeast.  They should all die down after sunset (7:30pm).

My favorite radar site for tracking the storms (when not at work) is here: 


Chief Meteorologist Mark Nelsen


7 Day Getting Warmer; New Podcast Posted

March 26, 2013

Steph and I bumped up temps a little on the 7 day this afternoon and I added a couple of degrees again this evening.  Models have been very consistent with a warm atmosphere overhead, sunshine, and offshore flow (at least on Saturday and probably Sunday) pushing temps at least to 70 degrees.  My “magic chart” shows a +10 at 850mb Saturday afternoon with offshore flow producing a high at PDX between 70-75 degrees.  Regardless, this weekend will be the warmest we’ve seen so far this spring and far better than we saw in March last year.


Right now we are running 3rd driest March at PDX.  We’ll probably get a little tomorrow afternoon or Thursday and that could bump us out of the top 5.  We’ll see.


We’ve got a fresh NW Weather Podcast posted!  Brian, Mark, & introducing Joe Raineri as our newest member of the weather team. Lots of fun, a recap of the “big” Hockinson tornado last week (don’t miss the telethon for the victims of the great twister!) and a look back at our sad (boring) winter:  You can check it out here:  http://t.co/OVx2jV0g5b

Joe started last week and he’ll be reporting weekday mornings and filling in weatherwise as well.  In fact his first weather shift is next Monday at 5pm.

Chief Meteorologist Mark Nelsen

A Very Dry March; Mild Weather Continues

March 25, 2013

9:45pm Monday…


What a difference one year makes!  Our temps this month are running slightly below average, but rainfall is WAY below normal.  And this weekend was great with excellent weather for getting outdoor projects done; so now my back is tired and I’m “relaxing” at work. 

Last year was our wettest ever March with 7.93″, constant rain and several bouts of wet snow to the lowest elevations.  This year no snow at the lowest elevations and very little even up around 1,500′.  Last year I had 20″ of snow at 1,000′ in March; this year just 1/2″ last Friday morning.  Right now we are at 1.46″ rainfall for the month.  Even if we somehow squeeze out another .50″ in the next 3-4 days (unlikely), that means we’ll be below 2″ for a monthly total.   That’s only happened twice in the past 20 years (2004 & 1994).  This March has been a very nice payback for the really wet March weather we’ve seen the past two years.  It’s especially pleasing that the eastern part of the USA is whining about how “winter won’t let go” as we finally get some nice spring weather for once.

I might be jumping the gun a bit, but a cursory glance at past springs shows that the under 2″ March totals are frequently  followed by a drier than average spring.  Interesting eh?

The next few days involve a real pain for forecasting.  Models are showing weak southwest flow over the Pacific Northwest as a new upper low develops in the Eastern Pacific to our southwest.   So we just have leftover moisture over us that afternoon heating work on.  Most likely we’ll see pop-up showers Wednesday-Thursday afternoons, possibly tomorrow or Friday too.  I’m not really seeing any low lifted index numbers or high CAPE; both would be an indication of nice spring convection.  But we could have some weak “action” those afternoons.  We’ll see what happens each day.

Beyond that, models all agree that the upper-low sits just off or on the California coastline over the weekend with upper-level heights rising off the SW BC coastline.  This is a nice block pattern with offshore surface flow and a warm atmosphere overhead.  The last few days of March we can get some very warm weather out of this.  850mb temps are forecast around +8 to +10 with abundant sunshine and some offshore flow.  That means high temps the warmest we’ve seen so far this spring; right around 70 degrees.  A +10 with perfect offshore wind flow and totally sunny skies has pushed the PDX high as high as 74 degrees in the past in the month of March (according to my chart).

So, it’s a risky forecast, not because of uncertainty, but because it’s a holiday weekend (Easter) and I REALLY don’t want to screw up the forecast.   Nothing’s worse than forecasting a nice weekend on a Monday and then having to back off on that later in the week.

Here are the two ensemble charts from today, the 12z GFS and the 12z ECMWF, click for a better view:

tseries_850t_000-360_Portland tseries_850t_000-384_Portland

Note the unusually high uncertainty beyond Sunday.  Models are all over the place for next week, although splitty flow seems to want to continue.  Split-flow is terrible in winter because it leads to boring weather and weak storms.  But split flow in the spring often means warmer than average weather and sometimes thunderstorm setups.  Example A:  a new wrinkle on the brand new 00z GFS, the upper-low to the south this weekend moves off to the east and ridging stays right over us on days 7-8 (MON-TUE) instead of a cold trough coming in from the north…very nice if you want mild spring weather to continue.

By the way, I’ll have very low tolerance for misbehavior or drama this week on the blog comments.  It’s been real mellow on here; could we keep it that way for a while longer?

Chief Meteorologist Mark Nelsen