April 2022 ends wettest on record, plus a possible tornado in Tigard this evening

9pm Saturday…

It’s rained a lot this month, in fact we’ve seen 24 days of measurable rain in Portland, just one under the 25 day record set in 2010. Oh that spring…yep, both 2010 and 2011 were something else. In fact we haven’t seen a cool/wet spring since that time. It’s possible that we’re now in “payback mode” for all the warm/dry springs we’ve seen recently. I am quite confident we won’t have a dry start to May, after tomorrow.

With just 3+ hours to go, it IS the wettest April we have seen in Portland. I think we are done with the rain so these should be the final numbers. Official PDX records go back to 1940.

(kptv)

Records have been kept at various locations around downtown Portland since the 1870s too. At that location, it’s probably the wettest since 1937 (over 6″), and only 1883 was wetter with almost 8″ of rain.
Do you remember LAST April? The DRIEST on record

(kptv)

Some other numbers around the region…

(kptv)

Notice Portland is wettest in the Willamette Valley. This is not the wettest April on record in either Salem or Eugene. Both have seen 7″ at some point. April 2003 was one real soaker. It’s also disappointing how little snow/rain made it into Central Oregon. We’ve seen lots of westerly flow in the lower part of the atmosphere and the Cascades block much of that moisture. The far eastern 1/3 of the state has done well though. Breaking the month down a bit more, only 6 dry days, but only 3 were really wet with more than 1/2″ rain. Lots of showery days.

(kptv)

We’ve all notice the cool temperatures too, but that hasn’t been record-breaking. 3 degrees below normal and the coldest in 11 years. This April is similar temperature-wise to 2003, 2008, & 2011.

(kptv)

Last night’s stratiform (steady) light/moderate rain combined with some heavy cells east metro this afternoon led to some big rain numbers. Gresham and Corbett areas picked up 1.00″to almost 2.00″. The 1.53″ and 1.65″ and 1.33″ numbers in Corbett are part of PGE’s new fire weather network. High quality Campbell Scientific instruments. They’ve also installed some of those around North Plains, Scotts Mills, and a few other fire-prone spots.

Heavy rain east Multnomah county(NOAA/NWS)

As the last of the showers were winding down this evening, it appears a weak tornado (or landspout?) touched down at Cook Park in Tigard. I’ll admit I briefly thought this video was fake, but then watched a couple more times. A child could have been crushed or anyone seriously injured as that heavy metal roofing few through the air. Notice the circular motion. If you listen closely you can hear the rush of wind and see it on the parent’s clothing just before it tears the roof off. Maybe a landspout? A gustnado? That 2nd one seems less likely since there was no widespread gusty wind occurring anywhere nearby, this was a highly localized gust. There are 3 home weather stations within a mile and they didn’t pick up any significant wind.

Enjoy tomorrow because May starts with dry weather…for one day. I think it’s very unlikely we stay dry as a wet system comes inland Sunday night and again late next week. I’m somewhat confident the streak of very dry Mays will end this year. Seems like 1″ of rain is likely just in the next week, possibly more. We will see if we get a “wet” May. that hasn’t happened since 2013! That would require a continuation of the cool/wet pattern with frequent upper-level troughs moving through the region.

(kptv)

That’s it for now. Happy May!

Spring 2022 turns cool & wet

Meteorological spring in the Northern Hemisphere runs from March 1st to May 31st. It’s the 3 month period between winter and summer. This year was looking a bit like last year through the first few days of April; a bit warmer and drier than normal.

How things have changed the past 10 days! Numerous rounds of cold showers and mountain snow have been the rule since the 10th. Take a look at temperatures so far this month in Portland. The dark blue days are high temps 10 degrees or more below average. So far we are running close to 4 degrees below average, one of the coldest first 18 days of the month we’ve seen.

Then the precipitation. Lots of it. As of this evening it’s the 8th wettest April on record with lots more rain ahead.

Compare that to the last two very dry Aprils. In fact we’ve already picked up more rain this spring than the last four!

Of course snow has been falling heavily at times the past 10 days. All basins in Oregon have seen significant improvement with PLENTY of water now available in the central/north Cascades and NW Oregon. We won’t need to worry about drought in the NW quarter of the state this summer. But a different story continues in central, south, & SE Oregon. It’s more a matter of “bad” instead of “terrible” for the irrigation season. You can’t erase two years of drought with 1-2 weeks of heavy mountain snow and rain

On April 1st, it was looking like we might have a quick melt-off once again. But check out the SWE (snow water equivalent) just east of Government Camp. That’s inches of water in the snowpack. Black line is this year. Notice it has suddenly swung back upward right when it is typically melting (green line)

The same thing at Clear Lake about 5 miles SE of that location. A dramatic change from two weeks ago!

WHAT’S AHEAD?

A cool upper level trough will be swinging through the region tomorrow and Thursday. The atmosphere was marginally unstable today and we could have seen thunderstorms west of the Cascades. But thick cloud cover kept things from getting going. Tomorrow should be a bit more interesting. A system moves overhead in the morning, followed by a cool and unstable airmass flowing in from the southwest. Models are giving us low Lifted Index, relatively high CAPE, and the SW to NE storm movement has historically been good for thunderstorms and possibly funnel clouds. Assuming we get plenty of sunbreaks, I expect scattered thunderstorms to pop up midday and into the afternoon hours. I’ve seen much better setups with better dynamics, but it always seems to easy to get a few storms going in April-May-June around here. Typically they are weak, but we’ll see if anything more significant shows up tomorrow. The NAM-3km shows the best CAPE around 5-6pm, although it shows more than other models.

My gut feeling is we have a typical spring shower/downpour day (with sunbreaks) on tap for tomorrow with a few embedded thunderstorms. Probably a funnel cloud or two as well. Check out this great timelapse of a funnel cloud last Wednesday evening.

Timelapse of Portland funnel cloud around 7:45 looking south from Central Eastside #orwx @NWSPortland @WeatherJefe @MarkNelsenKPTV pic.twitter.com/KYCM93miRn

— Ian Brady (@IanMBrady) April 14, 2022

ANY DRY WEATHER AHEAD?

Not really, at least more than a couple days at a time. I’d like to get a few cold weather veggies planted and I’m thinking that could be next Monday. That’s because it appears we’ll get some brief upper level ridging this coming weekend, then another cool/wet trough swings through next Tuesday/Wednesday. There are hints we turn a bit drier right after that time…around 9-10 days from now. You can see that in the ECMWF ensemble chart which takes us into the first few days of May. So the short answer is NO, I DON’T SEE A LONG DRY/WARM SPELL IN THE NEXT 10 DAYS.

The April 2022 bomb cyclone snowstorm

I almost never use the term “freak” while describing weather events, because media can easily overuse the word. But one week ago we saw a freak mid-April snowstorm in far NW Oregon and SW Washington. I use the term because, just like the heatwave last June, the setup is unlikely to be repeated again in my career (or lifetime?). The reason for this post (a week later) is that I want a good record of the event. I was out of the area. In fact I was on the other side of the planet, somewhere between Greece and Montenegro on a large ship. With little/no internet. Typically April is a “safe month” for a chief meteorologist to take a vacation. I hit the wrong week this year.

April is generally considered a relatively mild month weather-wise in our region. Cold showers mixed with warm sunny spells is normal. Sometimes those cold showers can contain snow pellets, hail, or even snow mixed in. At 1,000′ in the hills it’s not even unusual to get snow in April. I’ve had brief morning snowfalls a few times at my home the past 18 years in that location. There was nothing really unusual about Tuesday and beyond last week – lots of cold showers with thunder and hail. We have had some very mild Aprils lately, in fact April has been turning warmer as our climate warms. Notice how often we used to have sub-50 degree highs in the past compared to now.

But in the past 8 days we have reverted to a chilly pattern similar to what we’ve have seen in the past. We hit 75 the day I flew out of PDX. But then things went downhill around the 10th

That snowstorm one week ago goes WAY beyond a normal chilly April weather setup though. It was the perfect “snow storm” pattern that would have given us 10-15″ snow in the metro area if it would have been December-early February. Maybe most interesting is that it was almost perfectly forecast by models, yet (just like June heat wave) meteorologists were doubtful that such an extreme event could occur so late in the season and downplayed snowfall totals. I would have gone for lighter snow just like local mets did that Sunday ahead of time.

500mb forecast charts show cold air dropping south as a cold upper-level low sweeps across the area Sunday night through Monday night. 1st image is Sunday afternoon, next is Monday 8am. All these charts are from the WRF-GFS model.

By Tuesday another cold trough was swinging through, then the last of the really cold stuff moved by Wednesday

What has happening down below? The approaching trough spun up a very deep surface low. Notice on Sunday it’s about 1014 millibars (mb)

It crosses the coastline Sunday night around Lincoln City, then is east of Madras by 5am Monday. This wasn’t about “cold east wind” like wintertime. It was about very heavy precipitation dragging the snow level down lower than it would typically be during an event like this in April. At this points a breezy northwest wind had picked up across the snow storm area.

So at this point it’s down to around 993 mb. That’s a 20 mb. drop in 24 hours – technically a bomb cyclone passed right across Oregon last Monday! It’s rare to see a low deepening AFTER it crosses the coastline. By 11am Monday it’s way over in NE Oregon and you can see the dynamic cooling is ending over NW Oregon and SW Washington. Most lower elevation spots are changing back to rain at this point.

Those are some serious atmospheric dynamics (lifting and atmospheric cooling) going on around such a quickly deepening low pressure area. And it’s well known that the area just north of a surface low can give some great precipitation and snow totals. Take a look at the precipitation forecast from Sunday evening through Monday evening. 1 to 1.5″ likely, a big April soaker!

Now look at the snowfall forecast from the WRF-GFS from Sunday evening. Just about nothing south of Wilsonville or Chehalem Mtn. A foot is possible in foothill locations (and West Hills), 5-8″ in parts of Clark County and hills of Clackamas/Multomah counties. And 2″ in lowest elevations along Columbia River in middle of metro area.

To make a forecast of 2″ snow in Portland in mid-April, when that hasn’t happened anytime after first few days of March? I think I would have said Trace-1″ and left it at that. Quite a good performance by models!

The final snow totals…

FINAL THOUGHTS

• This was a historic event for our area. I’d say it’s similar to getting a couple of 90 degree days in mid-October. Or maybe similar to a 3″ snowfall in the city for Halloween? A freak snow storm for sure!
• 1.6″ fell at NWS Portland, and 2.0″ downtown, both the latest on record. 0.3″ fell the next day (officially), but that was mainly graupel and temperature didn’t fall to freezing. We will see if that number remains.
• The weight of extremely wet snow (falling at 33-34 degrees) approaches that of an ice storm. Lots of trees either snapped off or fell over under the weight. I lost all or part of two ornamental trees, yet they’ve been fine through several 1″ ice storms. No leaves on those trees either.
• It’s unlikely this will happen again in our lifetimes, or at least in the next 20 years. Everything had to work out PERFECTLY to get the heavy/wet snow down to sea level. Timing + precipitation intensity. Similar, but not as extreme, events occurred in April 1963 and April 1936.
• If it had occurred 6-10 hours later, it’s likely no snow would have stuck in the lowest elevations. Notice that Portland officially picked up 1.5-2.0″ snow, out of 1.40″ precipitation that day. It just barely worked out in the lowlands. The high later that day was 51 degrees! If we had been 25-30 degrees with this setup, a solid 10-18″ could have fallen in the entire metro area. The track of the low was similar to the January 1998 snow storm.
• Out of all that drama, we didn’t get a freezing temperature in Portland. Latest frost is still March 10th.

ABOUT THAT FORK

Each February, I have people asking me if winter is “over” in February. And each year they ask if it’s okay to turn on outside water spigots, take off the chains, or if we’re done with the chance for an all-day snow event. So about 15 years ago I started “forking winter”. Twice during that time I’ve been burned. In late March 2012 a heavy/wet snowfall of 1-8″ occurred in parts of the Willamette Valley. Then this year we had a real snowstorm 6 weeks after I pulled out the fork. To be clear, March and the first week of April was very mild this year and we are definitely in spring. Yes, it can snow in spring every 10-30 years in the lowlands. Just like it can get hot in fall or spring too, but that doesn’t mean it’s summer. I’m guessing the same people thinking I should drop the fork thing will be asking next February 20th… “Is winter over?” We will see!

Chief Meteorologist Mark Nelsen

A Late Spring Break

10:00pm Wednesday…

Just a quick note to let you know most likely I won’t be posting through Sunday April 17th (Easter Sunday).

If it snows this weekend in the hills, or a freak storm or tornado develops next week? I’m not ignoring it, I’m on vacation.

50th anniversary of deadly Vancouver tornado

9pm Tuesday…

It’s pretty well-known that the Pacific Northwest isn’t in “tornado alley”, but I think most of us know that we do occasionally get weak tornadoes.  Official tornado counts go back to around 1950.  Since that time in western Oregon, plus the SW Washington counties, 89 tornadoes have been reported.   That’s 89 in almost 70 years!  Obviously they aren’t too common.  The vast majority are weak; EF-0 or EF-1 category.

The last 4 years we’ve seen several EF-0 tornadoes across the region. 

And of course many of us remember the Manzanita tornado in October 2016 and Aumsville in December 2010.  Those both went right through the middle of small Oregon towns, a rare occurrence. Also note we’ve never seen an EF-4 or EF-5 in this region.

Tornadoes come out of strong thunderstorms and we don’t get many of those west of the Cascades.  That’s the main reason we don’t see tornadoes very often and when they do show up they are usually weak.  There is a bit of a tornado “season” both in late spring and fall.  Notice how rare they are in mid-winter and mid-summer?

Tornadoes RARELY kill people in our area but it happened just once.  That was on this date in 1972.  6 people died and 300 were injured.  I was just a little 3-year-old kid (living in Hood River county) so I don’t remember it, but I know many of you older folks do.

Storm Summary – April 5, 1972

1. A spring squall line with heavy showers and thundershowers swept through the region behind an early morning cold front.  Basically we were in a “showers and sunbreaks” weather pattern we often get behind cold fronts.
2. Around 1pm a tornado dropped out of a thunderstorm near NE 33rd and Marine Drive in Portland.  This was just west of PDX and quite close to the National Weather Service office (at the airport).
3. Tornado quickly moved across the Columbia River and through central/east Vancouver on a 9 mile trek toward Brush Prairie.
4. The deaths all occurred in a several-block stretch.  From around the Fort Vancouver H.S. track to NE Fourth Plain and NE Andresen Rd.
5. Just a few minutes later the tornado was gone after skipping out to Brush Prairie; lifting off the ground several times.

It’s easy to find lots of details about the tornado online; this link gives a detailed accounting of the storm as it moved through Vancouver:  https://www.historylink.org/File/8099

And here’s the official detailed storm survey/summary from the National Weather Service:  https://www.weather.gov/media/publications/assessments/Tornado%20Vancouver%20WA%201972.pdf

Ogden Elementary school was not rebuilt in the same location.  Instead a “new” Ogden Elementary was built about 3/4 mile to the northeast in just 18 months!

Chief Meteorologist Mark Nelsen