Juneuary Ends Wednesday and a Review of the Damascus Tornado

The weather sounds like the most inconsequential thing to talk about during these times, but if it weren’t for – you know – the global pandemic and revolution stuff – it would absolutely make front-line news. A tornado came through Damascus, OR yesterday evening! Take a look at this video from Tim Lussier… it’s not every day you see one of these things out your back porch.

Like most Pacific Northwest tornadoes, this one was very weak and was rated an EF-0 with 75 mph winds. Almost all of our tornadoes – this one included – are “cold core” tornadoes, meaning they are the result of a local area of strong circulation within a vigorous shower. The tornadoes spawned by supercell thunderstorms are actually the surface extension of the rotating updraft of warm, moist air into the storm, hence their designation as “warm core” tornadoes.

The tornado was 600 yards wide, which is quite impressive for our neck of the woods. It also stayed on the ground for a hair over two miles – a laughable feat on the Plains but a respectable one for Western Oregon. Five trees were either snapped off or uprooted, and one of them – a large poplar near Royer Road – fell on and significantly damaged three cars. For the full tornado report from the Portland NWS, click here.

“Juneuary” is one of my favorite weather terms.  I remember reading weather articles written by KOMO weather blogger Scott Sistek and UW professor/blogger Cliff Mass about ‘Juneuary’ in as far back as middle and high school. It seems to be a weather term unique to the Pacific Northwest, as all the definitions I’ve seen on Urban Dictionary have some reference to either Washington or Oregon.

We’ve definitely had our fair share of winterlike weather this June. Here’s Paradise this morning. Paradise still usually has plenty of snow this time of year (they are currently 33% higher than average), but it’s always pleasing to see snow in the mountains so close to the solstice!

With only a week remaining until the summer solstice, snow is still falling this morning (14 June 2020) up at Paradise (Mt Rainier National Park) where 100 inches of snow still remains on the ground. #WAwx pic.twitter.com/E2dm3E6nC0

— Mark Albright (@markalbrightwx) June 14, 2020

Take a look at the snowpack now compared to what it was a month back! Since it is mid-June, a lot of Snotel sites are bare – hence the fewer observations with our current snowpack. Still, note how dramatically snowpack has increased compared to normal over the Blue Mountains in NE Oregon/SE Washington, the North Cascades and Olympics, and especially over the Idaho Panhandle and Western Montana. The Canadian Rockies have seen a substantial increase in snowpack as well. On the other hand, snowpack has dropped dramatically from Central Idaho southward (I’m skeptical of those high readings in Utah).

No surprises with the temp & precip distribution so far this month, with Western Washington and NW Oregon being much cooler/wetter than average. Note how some of the places that saw the greatest snowpack gain (relative to average) over the past month had near-average precipitation but well-below-average temperatures. In the spring when our snowpack is melting, temperatures & melting rates play a much bigger role than precipitation and any added snowpack from late-season storms.

This cool/wet weather has done wonders for our fire danger, which is critical for us during such a tumultuous period. July fire danger has definitely decreased relative to what was predicted a month back. Unfortunately, this precipitation still hasn’t put a substantial dent in our long-term drought, so August and September could still be extremely active months.

Forecast

We currently have a pretty juicy occluded front off our coast emanating from a deep Gulf of Alaska low, with precipitable water values (the amount of liquid water if you condensed all water vapor in a column of the atmosphere to liquid) around 1.2-1.4 inches off our coast. The front is currently too far offshore to be seen on radar, but the front and its parent low pressure system make for an awesome satellite pic!

This front will track inland overnight and bring light rain to the Portland metro area shortly after midnight. Rain should increase in intensity through sunrise and remain moderate-to-heavy through late morning before the occluded front pushes through and we switch to showers and sunbreaks. Showers and sunbreaks should continue Tuesday as the parent upper-level trough behind this front moves over the area. We could see a few thundershowers both Monday and Tuesday afternoon/evening as atmospheric instability increases due to diurnal heating, but any storms that do occur should be brief and weak.

By Wednesday, we finally break out of this ‘Juneuary’ pattern as a ridge sets up along the West Coast and strengthens through the week. The below model charts show the ridge on 5pm Wednesday, 5pm Friday, and 5pm Sunday. As you can see, this ridge isn’t expected to be particularly strong and we’ll still see onshore flow, but it’ll be strong enough shunt the storm track north into the Alaskan Panhandle and give us warmer and drier-than-average weather. Most mornings may see a few low clouds in spots (especially towards the coast and around the Puget Sound lowlands), but these should burn off in the afternoon.

It’s a way out, but models are currently in good agreement that this pattern will remain in place next week. The Climate Prediction Center is going for above-average temps throughout the West with just a slight chance of above-normal precipitation over Northern California and Northern Nevada due to the potential for weak afternoon t-storms.