Mellow Midsummer Weather

July 24, 2016

9pm Sunday…

I’m back from vacation and working hard in the weather center this evening.  Well, the weather is slow so I’ve spent more time on normal/mundane “office tasks”.  Such as: catching up on emails, doing schedules, planning software upgrades etc…and I even vacuumed out the dirty area behind the green wall that’s been bothering me for months.  I think I had empty boxes and junk  thrown back there from almost two years ago.  As a result I’ve kept quite busy considering it’s almost the slowest time of the year weather-wise.  I think only September and early October are more boring for us.

HIGHLIGHTS FOR THE NEXT 7 DAYS

  1. Cooler the next two days, but temperatures just come back down to about normal
  2. A 3 day period of very warm to hot weather Wednesday-Friday
  3. This will be the first hot weather since early June.  That’s if you define 90+ as “hot weather”
  4. 95+ is unlikely, and no records will be broken
  5. Back to typical clouds/sun mix with highs 75-85 the first week of August

 

Speaking of slow weather, we are in the warmest few weeks of the year and our 7 day forecast takes us through the last day of July now (next Sunday).  So far this month has been a notch cooler than average here in Portland and right at normal in Salem and Eugene.  The Oregon coast has been warmer than normal; not sure why unless it’s the lack of strong northerly wind compared to some other summers?  You can see in general the farther north you go along the West Coast the cooler it has been compared to normal:

anomimage

Compared to California which has been normal to slightly above.  Nothing too dramatic west of the Cascades/Sierra anywhere along the coastline.  Yet east of the Cascades the cool July sticks out in Oregon, Washington, & Idaho.  I would guess no one is complaining in those typically hot areas.

Today’s 88 in Portland was the 2nd warmest of the month.  Seems strange to say we haven’t hit 90 in Portland this month…and it’s the 24th of July.

Even more strange, we’ve gone through 7 weeks in the middle of summer in Portland without hitting 90 degrees!  That’s a huge contrast to the past 3 Julys.  More like 2012 which was not exceptionally cool by any means but 90+ held off until early August.  Clearly something “switched” after the first week of June this year as mentioned in a previous posting.  We went from a crazy warm spring again to just about normal now for the past 7 weeks.

Looking ahead, we have a weak marine push tonight and then a bit more tomorrow night.  The result is a few more patches of morning clouds and slightly cooler temps each day.  Then Wednesday through Friday we get 3 days of very warm to hot temperatures.  Right now I’m going with 88-92-95.  Hardly record-breaking hot weather (records 100-107) in this upcoming period) but the warmest we’ve seen since early June.  The reason is weak and “flat” upper-level ridging developing along the West Coast.

Take a look at the 500mb pattern for Friday morning, the peak of the warming overhead:

500vty_f120_bg_NA

You can see an upper-level disturbance dropping out of Alaska and it’s headed right into the Pacific Northwest next weekend.  Thus a very quick cooldown next Saturday/Sunday…could even bring a spot of drizzle inland next Sunday AM.  This is in stark contrast to what models were showing 2-4 days ago.  At that time models were giving us a big heat wave with temperatures well above 100 degrees.  This graphic tells the story, although it does use the typically inferior GFS model:

Capture

Let me explain.  Each HORIZONTAL line is one run of the GFS.  The latest is on the bottom.  These are 850mb temperatures, which means temperatures in celsius around 5,000′ elevation.  Go UP the chart to go back in time for the forecast for any particular date which is VERTICAL.  Focus on the circled areas; next Friday-Sunday.  See that 72 hours ago up to 48 hours ago the GFS was giving us +25 to even a +28 temperature.  That’s up in the 103-107 range with any sort of offshore flow.  I’m sure some of your automated apps showed 100+ weather during that period.  Since 48 hours ago models have continued to gradually back off on temperatures AND cut off the end of the heat wave.  So we no longer really have a heatwave forecast.  It’ll be plenty hot late week, but nothing unusual for late July.  I think most of us would agree that’s a good thing!

Looking farther ahead, we return to average temperatures for the first week of August.  Other than the drizzle possibility, no rain is in sight.  Keep watering!

Chief Meteorologist Mark Nelsen


Vacation Time

July 14, 2016

511646_12704_613757

Cue the Mark vacation jokes in 3…2…1…

I’ll be off on vacation for a wedding and a little trip up to B.C. mountain biking, plus painting my house through next week.  I’ll miss 6 work days and be back on Sunday the 24th.  Likely no posts during that time.

It’s the best & warmest weather of the year in the Pacific Northwest (mid-July to mid-August) so get outside and enjoy it!

Chief Meteorologist Mark Nelsen

 


This July Is Sure Different!

July 12, 2016

9pm Tuesday…

It finally happened!  Tuesday I received my first two “I HATE THIS SUMMER” emails.  Actually they were more like “WHAT’S GOING ON?” emails lamenting the lack of warm weather this summer so far…  Here’s one, click for a better view:

Capture

Let’s look at the facts first.  Temperature anomaly (departure from the average) for the past 10 days:

anomaly_10days

Coolest part of the USA compared to average is right over in the NE part of Oregon and northern Rockies.  July so far…

anomaly_july

Same general idea with a good chunk of the USA cooler than normal.  Now back 30 days; that started just a few days after our 100 degree Sunday!

anomaly_30days

This coolish pattern has been going on awhile…as mentioned in previous posts, it appears some sort of climate “switch” was switched on/off after the first week of June.

But we haven’t been all that cool; in fact Salem and Eugene have seen perfectly normal temps for July!  The coast has actually been warmer than normal.  So it’s not like we’ve seen a “chilly” July.   I think we have just become comfortable with warmer than normal temps of the past few summers, or at least we get used to it.  Specifically many of us have expected we can go out and enjoy those water sports just about any day in July and not be chilled.

This one graphic  tells the story:

Mark_80DegreeJulyDays

Last year 25 days at/above 80 degrees, this year it appears we’ll see 5-6 at most in the first 20 days of the month.  That’s MUCH different than the past 3-4 years!

The reason we are seeing the much cooler temps?  A flattened western USA upper-level ridge along with cool upper-level troughs wanting to hang out near the West Coast.

WHAT’S AHEAD?

Models beyond the 7-10 day period have been quite poor at forecasting this pattern.  They have been continuously pushing the ridge back to it’s typical summertime position in the 10-15 day timeframe.  So confidence on a switch to normal or above normal weather is quite low until it shows up within the 7-10 day period.  That said, we do have some warmer and sunny weather the next 3 days, then models have backed off a bit on the upper-level low this weekend.    The ECMWF ensembles keep us near/below normal for the next 10 days.

ecmwf

The GFS ensembles are a bit warmer, but I’ll trust the ECMWF for now and assume this pattern will continue through at least the 20th-22nd of the month.

By the way, there was quite a bit of frost in south central and southeast Oregon Monday morning.  Burns dropped to 30 degrees, although not as cold as the record July cold temp…25 degrees back in July 1986.

MarkTemperature_BurnsRecordLow

Winter is never TOO far away in Burns is it?

Chief Meteorologist Mark Nelsen


A Soaking For Some This Weekend

July 10, 2016

9pm Sunday…

Not such a bad weekend in the metro area, definitely better than I expected.  At my home I had very little rain Saturday and Sunday.  Definitely some wet stuff on Friday though, especially early and again after dark.

Luckily some of the driest parts of our region DID get a soaking…very rare in mid July!

MarkRainJulySoaking

Today there was almost no shower activity, or at least very light showers in the metro area.  Yet somehow 3 cold-core funnels were spotted.  Remember these are not dangerous and just indicate some twisting or rolling of the air above.  If one develops well and touches the ground then that would be called a tornado.  I have not seen any pictures but the NWS did get those reports from Kalama, North Plains, & Canby.

KPTV_Default

This work week Monday-Friday appears to be mainly dry, but with temperatures remaining mainly below normal.  The one shower chance is Tuesday.  And the warmest days should be Wednesday/Thursday.

Models are showing another cool upper-level low dropping into the Pacific Northwest next weekend.  As of now, the moisture supply appears to be far more limited compared to what we’ve seen THIS weekend.  So I just put a chance of showers with cooler temperatures next weekend.  We’ll see how things develop the next few days.  IF YOU HAVE BIG OUTDOOR PLANS FOR THIS COMING WEEKEND pay close attention to the forecast.  But for now there is no reason to freak out…yet.

Chief Meteorologist Mark Nelsen

 


July Turns Cool: A Short-Term Climate Shift?

July 6, 2016

Remember the record-breaking “heat” earlier this spring with a bunch of 80s in April and May?  It’s payback time and that is the big weather news this week.  It appears we have a cool July developing for the first time in years.  

FORECAST QUESTIONS:

Will we get a big soaking this weekend?  I don’t think so, at least not in the lowlands.  Note the RPM total showing light amounts in the valleys…no models are showing more than 1/2″ rain.

RPM_RAIN_NWOREGON

Will my wedding/garden party get rained on Friday, Saturday or Sunday?  Possibly, but the pattern for Friday/Saturday is a showery one, not the “all day downpour” stuff.  Current thinking is that portions of each day will be wet but as of now we can’t time those showers.  Our RPM (not always a stellar performer) actually has most rain offshore Saturday with just a few light showers in the valleys.  That would be nice.

QUITE A CHANGE THIS JULY!

The last two Julys have been real scorchers.  2015 was the 2nd hottest on record and 2014 was the 4th hottest.  2013 was just a little above average.  This follows 3 very cool Julys:  2010-2011-2012.  Take a look at the past 30 years in the western lowlands of Oregon…this is a bunch of weather stations averaged together:

July

You can see the big swing down and then back up the past 6 years.  Also note the upward trend the past 30 years.  So yes, what goes up must come down, but over time the high points are getting higher and low points not so low as our climate very slowly warms.

But now it’s payback time since this month is actually running BELOW average already and there is no sign of above normal temps in the next 10 days!  Keep in mind the 30-year average high temperature is 80-85 in the Willamette Valley during this period.  Highs in the 70s are considered cool (although comfortable!).

Here’s the plan for the next few days:

MarkHeadlines_SummerTakesBreak

It’s because of a cold upper-level trough that’s going to settle in over the Pacific Northwest this weekend.  See the 500mb height anomaly on the ECMWF this coming Sunday AM?  Then a 2nd one on Tuesday:

Check out the GFS for Sunday the 17th…hints of ANOTHER trough trying to drop into the Pacific Northwest for the following weekend.

The natives will be getting restless if we go through TWO mid-July weekends with clouds/showers.

It’s pretty obvious to me that SOMETHING changed after the 7th of June.  Since that last of the “spring heat waves”, we haven’t seen strong upper-level ridging or unusually warm weather.  In the last month we’ve seen only two days in the upper 80s in late June; that’s it…near/below normal temps otherwise.  My gut feeling is something has switched but I don’t know what.  Sea surface temperatures are still a little above normal offshore as they have been for a few years, although a narrow near-shore cold anomaly is showing up now.  This is low-level stuff and not a reason for upper-level patterns to shift:

Capture

One more thing I’ve noticed since that last heat wave in early June too.  Models have struggled to latch on to the persistent “cool” weather.  Over and over 10+ days out warming has been showing up yet as we get closer models back off and we end up in coolish or normal temps.  Interesting that it’s a total reversal of the “oh look, a surprise warm spell has popped up again” pattern all spring long.

Another even larger question…is this the much-anticipated end of our 2+ year warm spell?  As mentioned many times in the past two years we have been in a warm period since March 2014.  We haven’t gone more than about a month with normal/below normal temps before returning to the above average stuff during this period.  IF both July and August are cool, then that will be a dramatic change and we have seen some sort of climate switch.  Only time will tell as they say…

Meanwhile, check out this beautiful but scary pic of Super-Typhoon Nepartak nearing Taiwan this evening.  That category 5 storm will hit the island nation in about 12 hours.

himawari-8_band_03_sector_04_20160707042900

Find the high-res loop here on the RAMMB site:

Chief Meteorologist Mark Nelsen

 


Marine Inversion Is Gone = More Sunshine

July 3, 2016

Making my forecast here at 3:30pm (I work Sundays-Thursdays now) and I’m noticing it’s sunny just about through our whole viewing area.  This is on the day that we figured would be quite cloudy and cool.  We got the cool part right; but not the clouds.  I doubt anyone is complaining but let me explain…

During a good chunk of the summer we are under a marine inversion…quite strong on the coast and it comes/goes in the valleys.  That means relatively warm air is sitting over the Pacific Ocean-chilled airmass down near sea level.  But you can see what has happened today on the Troutdale profiler image below.  Time goes from RIGHT TO LEFT on this graphic:

Capture

This is temperature (well, virtual temperature but more/less the same thing) and wind direction/speed from the surface up to around 5,000′.  Note that yesterday AM/Midday it was cool above up around 4-5,000′, as you would expect.  But there was a second area just about as cool down around 3,000′.  That was the top of the “cool” marine layer.  It mixed out nicely in the afternoon, but you can definitely see the weak inversion.  Today is totally different with much colder air arriving above 3,000′.  You can see temperatures go from real chilly at 5,000′ up to reasonably cool down here at the surface AM/Midday today.  The result is a weak to non-existent marine inversion today.  That allows mixing and drier air to break up the cloud cover.  The end result is a sunny and pleasant 2nd day of the 3 day weekend!

The next 2-3 days appear to be similar, so I’m sticking with the morning clouds to afternoon sun routine through Wednesday.

Chief Meteorologist Mark Nelsen


Independence Day Weekend Outlook

June 30, 2016

Planning to go camping at the Coast or in the Cascades this weekend?  I’ve got your forecast covered.  Same thing if you plan to head east of the Cascades.

HIGHLIGHTS:

  • In general this 4th of July Weekend will be mild to slightly coolish (mainly Sunday) around the Pacific Northwest.
  • Who is guaranteed dry weather?  Anywhere south of Portland west of the Cascades and anywhere east of the Cascade crest & eastern Gorge.
  • Who MIGHT see a shower?  North Coast, mainly on Sunday AM.  Same thing from the metro area north into SW Washington…again on Sunday AM only.
  • Afternoon temperatures: 60s at Coast, 70s in valleys, and 80s east of the Cascades
  • Varying coverage of morning/midday clouds will continue west of the Cascades
  • Expect mainly sunny skies all 3 days anywhere east of the Cascade crest.  That also includes the Columbia River Gorge east of Bonneville Dam.

Here are the graphics showing a few more details for each area:

MarkMemorialDay_Coast

MarkMemorialDay_Cascades

MarkMemorialDay_CentralOregon

This pattern will continue through the entire week ahead.  High temperatures will remain at/below 80 degrees west of the Cascades.

Chief Meteorologist Mark Nelsen

 

 


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