Yep, it was cold! Coldest September day in at least 71 years in Portland

September 29, 2019

8:00pm Sunday…

No, you aren’t crazy; today felt like Thanksgiving Day outside.  Cloudy, rain showers at times, a breezy and chilly east wind blowing out of the Gorge etc…

Todays Observed Highs OrWa 2017

Officially it appears Portland only hit 52 degrees at the airport.  That’s ties the all-time coldest September day.  It hit 52 on September 26th 1948 as well.  That’s an average high for the 3rd week of November around here.  For the first time a cold east wind was blowing through the Gorge too, gusts up around 35-40 mph.  This is due to a modified arctic airmass that has spilled south out of Canada.  Compare this to the coldest day each of the past few Septembers

September Coldest Day

We were probably complaining about those lower 60s too…

By the way, there is still an observing site in downtown Portland and the preliminary high there was only 49.  If that holds, that means it may have been the coldest September day in Portland in 145 years!  That said, the downtown temperatures records are a bit sketchier, sometimes on top of very tall buildings and they’ve been moved around quite a bit.   Regardless a high temp around 50 shows how rare it is to see an airmass this cold so early in the season.

Of course it’s been snowing in the mountains since Friday night and a LOT has fallen above 5,000′.  These are estimates, based on pics, ski area reports, and NW Avalanche Center telemetry.  There is

Snow Mt Hood Totals

The next 7 days look uneventful…lots of sunshine and a couple cold mornings ahead.  A few outlying areas could see light frost tomorrow or Tuesday morning.  Just in case, bring in anything that shouldn’t freeze tonight.  No, not pipes/hoses etc…just plants.  We’re talking just a bit of frost touching the plants, not a freeze.

Forecast Tonight Metro

Alright, so the #1 question I keep getting is:

DOES EARLY MOUNTAIN SNOW & REGION-WIDE COLD MEAN ANYTHING FOR THIS COMING WINTER?

I think the short answer is NO.  What happens in September or October typically doesn’t have any positive correlation to the following winter that I’m aware of.   I’ve never noticed a weather pattern in these months that repeats through the following winter season.  But just for fun, let’s see.

Because this cold/snow event is so early in the fall season, there aren’t many winters to compare this one too.  For example, late September or very early October snow has only been recorded 4 autumn seasons at Government Camp.  3″-1984, 2″-1972, 2″-1971, and then October 4, 2009 when 3″ fell. Then let’s take 1948 as the other year we only hit 52 in Portland in September.  There were 3 very chilly days in late September that year.  So that gives us 5 years with very early season snow at Government Camp and/or very cold lowland temps.

What happened the following winters?

Winter 1948-49 

23″ snow in Portland that year, mainly January and February.  Extremely cold January 1949.  Nov, Dec, & Feb brought big snow to mountains.  466″ total for winter at Santiam Pass.  A very active winter with lots of lowland snow and extremely cold January

Winter 1971-72

Good snow year in Cascades, in fact 3rd snowiest winter at Government Camp.  But that wasn’t reflected down in Portland, 5″ snow for winter season.  An active winter with big mountain snow but nothing too unusual in lowlands.

Winter 1972-73

Extremely cold arctic blast early-mid December, 6″ snow fell in Portland that month, but little/no snow rest of winter.  A relatively dry winter with no real good Cascade snow until later in December (slow ski season start).  Crazy cold early, then a typical winter otherwise.

Winter 1984-85

Big October snow in Cascades and good ski season start.  Then NO snow with a massive ridge overhead all of January.  I remember that one.  Fog or east wind all month (depending on where you lived).  Then tons of February snow in mountains and even some lowland snow that month.  It was a relatively active winter, but with a weird “stoppage” in January.  8″ total in PDX.

Winter 2009-10

Other than a December freeze, a classic mild El Nino winter.  Only one 3 hour snow event (the December 29, 2009 commute debacle) in Portland.  This was the 2010 Whistler Olympics when it was very mild and they didn’t have enough snow at some of the venues.  Cascades didn’t have a very good snow year.  Only 9″ fell at Hood River all winter in the Gorge.  A mild & “boring” winter much of the time.

I suppose one could argue that in each of these “early cold” years at least SOME snow fell in Portland the following winter.  Maybe that’s because this big ridge offshore and cold trough dropping through Canada tends to repeat in the following months?  That’s a possibility.   As mentioned in previous posts, the current pattern is what gave us the record cold/snowy February this year.

One more thought…we’ve now seen three consecutive winters with 6″ or more snowfall at PDX.  The last time we’ve seen FOUR is way back in the mid 1950s.  We’ll see if it happens this year

PDXSnow

Chief Meteorologist Mark Nelsen

 

 


Thunderstorms Pop Up Over Central & East Metro

September 29, 2019

4:25pm Saturday…

Today has been uneventful in the lowlands…until a line of thunderstorms formed over the southern Washington Cascades and dropped down into east Clark County.  These storms have slid south across the Columbia River and into East Portland, along and east of I-205.  Notice how nice it is Downtown right now, but dark skies and thunder to the right

cam

Radar shows the heaviest action is over NE Portland & Parkrose right now, headed directly toward southeast Portland & Milwaukie.  It’s plenty cold for lots of hail too.

web_metroradar (1)

I see Clark Public Utilities has over 20,000 customers out…that’s a lot of lightning-related outages.

Showers have been powered by the very cold air overhead and relatively “warm” air down here at the ground.  A 60 degree high when it’s around freezing up at Timberline is an unstable atmosphere.  By the way, it appears Timberline has picked up 7-8″ of new snow so far.

So keep an eye to the sky the next 2 hours, storms are moving from north to south.  Showers and thunderstorms will die down as sunset approaches.

Chief Meteorologist Mark Nelsen