Vacation Time

July 7, 2014

I have this week off; it’s summer vacation time.  So no posts, but you aren’t missing much anyway.  Enjoy the sunshine, marine air with its clouds, and blue skies…

I’ll be back on Monday the 14th

Chief Meteorologist Mark Nelsen


Happy Independence Day! Nice Weekend Weather

July 3, 2014

Did you know the 4th of July is the wettest day in July…on average?  More on that in a minute…but first we have a very nice weekend coming up.  Other than a weak weather system giving us lots of high clouds Friday and maybe even a coastal sprinkle, expect widespread sunshine and warming temps Friday through Sunday.

Mark_4th-of-July_History1

The average high temp for the 4th is 78 degrees, and the chance for getting measurable rain is 24%, which also happens to be the highest chance for rain of any July day!  Interesting eh?  Even more fascinating is that my kids, heading into 7th/8th grade, have never seen rain on the 4th!  Maybe we need to retire the old “summer starts after the 4th of July” statement?

Mark_4th-of-July_History

Speaking of summer, temperatures warm through Monday or Tuesday as very high upper-level heights (lots of warm air) build over the West Coast.  It’s not going to be a sharp upper-level ridge, but more a very large area of warm air.  So we won’t see a thermal trough with the easterly wind like earlier this week.  Luckily that means no real hot weather; I think it’s unlikely we’ll get above 90 degrees.  And a high of 90 in Portland in early-mid July is nothing unusual; about 10 degrees above average.  Such a large ridge will keep the marine layer squashed quite low so we won’t see much morning cloud cover through at least Tuesday/Wednesday.

Summer 2014 is definitely here.

Chief Meteorologist Mark Nelsen


Today was “Melt-Out Day” on Mt. Hood

July 2, 2014

Have you ever wondered how long it takes all the snow in the Cascades to melt?  Of course it depends on the elevation, with higher elevations (cooler temps) taking longer.  Well today was the day the Mt. Hood Test Site saw the last of its snow melt.  Actually the snow depth sensor finally went to zero yesterday, but the “snow pillow” that measures snow water equivalent is still seeing a little.  I’m not a sensor expert, but decided today was close enough.

I’ve had some spare time at work the past few days, so I wanted to see if the date at that location is earlier or later than in the past.  You might be surprised at what it shows!  Data at that location at 5,400′ goes back to 1981.

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You can see the earliest was the drought year 1992 when the snow disappeared by May 25th.  The latest was just three years ago in 2011, when the last of the snow disappeared the 2nd week of August.  Now the data period is quite short; only about 30 years, so don’t try to draw any earth-shattering conclusions, but the trend is definitely for a slightly later melt-out in the past 9 years.

I think it’s fair to make these two statements as well:

1. At the 5,400′ elevation on Mt. Hood, the snow is not melting any earlier than in previous decades.  If anything it is sticking around longer.

2. The Cascade snowpack AT THAT ELEVATION and IN THAT LOCATION is sure not disappearing!

 

When I get some more time I think it would be interesting to see if lower elevation locations are similar, such as 3-4,000′ spots.

Chief Meteorologist Mark Nelsen


99 Final High Temp Today

July 1, 2014

Sophie High Was it the warmest day of this summer?  One would hope so, but historically it’s unlikely we’ve had our warmest temperature so far.  Take a look at just the past 10 years.

MarkYearly_DateofHotHighTemps

Last year the 97 on June 30th was the hottest of the summer.  The average over the past 10 years is July 28th, and you can see in about half the years the hottest of summer is in late July or August.

Cool marine air is surging inland nicely at 11pm with temperatures in most of the Willamette Valley down to around 70.  That cool air will continue to pour in through tomorrow.  High temps should be 15-20 degrees cooler as a result.  Part of the cooling will come from extensive mid-level clouds the first part of tomorrow due to an upper-level disturbance moving by.

Ahead of that disturbance this evening there is quite a bit of thunderstorm action moving north along the east slopes of the southern Oregon Cascades…actually heading into the Central Cascades at this hour.  So I wouldn’t be surprised to see flashing to our southeast within a couple of hours.

Chief Meteorologist Mark Nelsen


98 Today…As of 5pm

July 1, 2014

What a mid-summer scorcher today, take a look at the high temps!

PLOT_Highs_Metro

We get the high temperature from official observing sites every 6 hours, which in summer is 5pm and 11pm.  Now the 5pm temperature IS 98 degrees, which means it’s possible we’ve gone to 99 and don’t know it.  Portland NWS also puts out a climate summary around 7:20pm just for the PDX site which means for that site only we’ll really know what the high temp was.  Got all that???

More later…

Chief Meteorologist Mark Nelsen