Early December won’t quench Portland’s thirst for snow


No snow for Portland in the forecast

Nov. 30 radar image from the KOIN6 PDX Wx App

PORTLAND, Ore. (KOIN) — Valley snow, metro snow, Portland snow! Those. Are. Fighting. Words. Low elevation snow stirs deeply embedded emotions.

I know this because I live it every day.

Right off the bat, I’ll tell you we do NOT see any PDX snow in the near future. Nothing through the middle of December. I am seeing a few wintry hints though just before Christmas. This is not intended to be a build-up to a letdown or that crazy click-bait that some organizations use regularly. I’m here to inform you in the most transparent way possible.

“It’s safe to safe we don’t get snow very often in Portland. Period,” Tyree Wilde, a warning coordination meteorologist with the National Weather Service’s Portland office, said.

Bingo! I think we can all agree that lasting, measurable snow in Portland is a bit like a unicorn. Take a look at how infrequently any location in the valley gets measurable snow, not to mention the rare possibility of seeing snow before the first day of winter (The winter solstice on Dec. 21 at 8:19 p.m.).

courtesy Oregon State University
courtesy Oregon State University
courtesy NWS Portland
courtesy NWS Portland

Two weeks before Thanksgiving long-range snow accumulation models offered a lot of eye candy: 7 inches of valley snow, 4 feet of mountain snow, it was all out of the norm for November. These are images we would not use to advertise a forecast so far out from event time. Look here it’s a 10-day forecast for snow accumulation.

Euro depiction of 10 day snow totals for Thanksgiving. This forecast did correctly predict more than 2 feet of snow for the mountains, but missed the mark on low elevation snow. No surprise considering how far from event time this model run was released. See initialization times and valid times on top.

A week before Thanksgiving generic weather apps were pinging snowflakes for the holiday. So, like a good meteorologist, I silently prayed it would come true (minus the kale & bacon runs) knew in my heart it would be unlikely, and carefully watched every model run.

When potentially hazardous weather arrives during a busy travel period I dive deep into research mode.

I asked coworkers and other professionals what they remembered from Thanksgivings past. Most could not recall a time with measurable snow so early in the season.

“We go back and look at the airport and we have had snow in November 16 times since 1940. Downtown we’ve had it 17 times in November. At the airport, the last occurrence we had for snow in November was 0.6 inches in 2003,” Wilde said

In my discussion with Wilde about the reliability or lack thereof in long- term model accuracy, he points out why these generic weather apps are quick to put out a snowflake sometimes a week in advance.

“I think what some of those apps are hinting is what we’re able to do is ensemble forecasting now, numerical models, different initial conditions, different physics in them, some of these members are 50 members, 50 different members in these ensembles,” Wilde said. “Maybe one ensemble member shows snow and all the rest of them are not. What you have to do is take them with a grain of salt and really ask what’s out most likely situation?”

If I were Captain Ahab in Herman Melville’s Moby Dick, Portland snow would be my white whale.

Valley snow creates madness. It can empty grocery stores and bring a roar of studded tires to the streets. When snow falls, people run outside to measure microscopic fractions of an inch and tweet it with pride. Some drivers have been known to abandon their cars and walk on the road like it’s the apocalypse. If you’re a snowflake forecast to land in some corner in Portland, beware, ’cause residents are watching you as if you owe them money.

Snow or not, I think the weather hazard that deserves attention right now is drought. The latest look at Drought.gov reveals that nearly 65% of Oregon and 68% of Washington is in the abnormally dry category, a precursor to drought. But what about all that wacky Thanksgiving weather and bomb cyclone? Not enough moisture, despite the damaging winds and mountain snow.

So what is abnormally dry? It’s short-term dryness, according to Drought.gov, slowing planting, growth of crops, some lingering water deficits, pastures or crops not fully recovered. November 2019 was the fifth driest November on record. PDX collected 1.52 inches of rain last month but the average is a little over 5.63 inches.

Here’s a look ahead into the next month. Above normal temperatures and precipitation for December.

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