I haven’t posted for awhile, mainly because the weather pattern hasn’t changed much. This hasn’t been an especially busy time for meteorologists in the Pacific Northwest!
Don’t get me wrong, it’s been a WONDERFUL spring outdoors west of the Cascades. I can’t believe how many days I’ve been greeted by bright sunshine outside the window since early March. I’ve spent almost my entire life west of the Cascades in Oregon and Southwest Washington. And I sure don’t remember a spring like this one! Day after day of dependably dry weather for outdoor activities. Sure, some years we’ve seen very dry weather in April, or May, or parts of each month. But never continuously from March through mid-late May! We were cool in March, but then since that time temperatures have been much warmer than average. We are living through a “central/eastern Oregon spring” this year west of the Cascades. It’s real nice, but you’ve noticed a lack of trees and in general a lack of green east of the mountains right? That’s what would happen here if every spring was like this one!
WHERE WE STAND RIGHT NOW
After checking some weather stats…
- Portland & Astoria are experiencing the driest spring on record so far (March 1st to May 16th). Only 2.01″ at PDX in the last 2.5 months! Rainwise, March was like a typical June, and both April+ May have been drier than a typical July! You see the result…grasses already are drying as if it’s late June or early July. The ground is hard and dry as if we’re in early-mid summer. Not good. Pendleton is 2nd driest, and Salem is seeing the driest in 82 years (1939). Portland hit 83 today, the 8th time this season.
2. Snowpack has melted much quicker than normal since April 1st. What WAS a great snowpack, well above average in northern Oregon, is now well below what we would typically see in mid-May. Or, in many spots it’s gone. Take a look at the Mt. Hood Test Site. Black line is this year, representing snow water equivalent. Basically how many inches of water are contained in the snowpack at 5,400′ near the bottom of Pucci Lift at Timberline. GREEN is an average year. The “X” in late April signifies the average “peak snowpack” date and number. In an average year, the snowpack at this location peaks out in late April, then melts out totally by July 1st. But this year saw an above average snowpack. It peaked early, but has been melting much more rapidly than normal. At this rate it’ll be gone at least three weeks early.
3. Many Willamette Project reservoirs (Detroit, Green Peter, Lookout Point, etc…) will not fill this year. A few have even begun to drop already. Detroit Lake is still about 18 feet below where it should be this time of year.
4. The Klamath Project has so little water that both irrigators and fish lose this time. For the first time in 114 years, no water will be sent into the main irrigational canal this year. The AP calls it the “worst water crisis in generations” in southern Oregon. Read more here. I remember 2001 and the war over water then. Looks worse this time.
Some answers to a few questions I’ve been getting…
ARE WESTERN OREGON SPRINGS GETTTING DRIER DUE TO CLIMATE CHANGE/GLOBAL WARMING?
NO – Actually spring rainfall has been very slowly rising the past 100 years. That said, it’s possible that global disruption in circulation (induced by man-made warming) can bring more extremes. Of course there is lots of debate over that. You can see in the 128 year history of Salem spring rainfall, no real obvious trend, But LOTS of ups and downs. Every year is different; we have periods of wet springs, then dry springs. This is one of those very dry years, like 1992, the first summer I was forecasting out of college.
IS THERE STILL TIME TO “CATCH UP” BEFORE SUMMER?
Technically YES, we COULD get 6″ of rain between now and the end of June. But that’s VERY unlikely. Look at the rainfall we’ve received at PDX from this point forward to the end of June over the past 10 years in the chart below. Somewhere between 2-3″ is normal for this last part of spring and early summer. If we have a June like last year (wet!), that would alleviate some short term water issues, and maybe fill more reservoirs. But July-September would still be a problem. We will need a long wet season next fall/winter. At this point the choice seems to be between “somewhat serious water issues” vs. “historic water issues”. That would be with respect to water supply, groundwater, & vegetation survival.
DOES THIS MEAN IT’LL BE A HOT SUMMER?
We don’t know. There’s no specific reason to think this coming summer will be hotter than normal, although that HAS been the trend for quite a few years. We haven’t had a “cool summer” in almost a decade. Some years we do get a soaking of rain in late August. That would be nice this year.
DOES THIS MEAN WE HAVE A TERRIBLE FIRE SEASON AHEAD?
It could be. Of course the “table is set” for a bad fire season with the early warm & very dry weather. But FAR MORE IMPORTANT is what happens weather-wise DURING fire season. I’ve seen bone-dry conditions in June, then we get occasional cool/moist periods later in July and August, leading to no significant fires.
Lightning is very important too. More lightning = more fires. Less lightning = better fire season.
WHAT’S AHEAD WEATHERWISE?
- There’s no sign of a significant pattern change (soaking widespread rains) in the next 10 days. That puts us into the last week of May
- But we WILL see some rain in these next 10 days, just not enough to alleviate drought/water concerns.
- Temperatures will be milder again (closer to normal) all this work week and into next weekend. There’s no sign of a heatwave. That is one thing we’ve avoided this spring, no extended periods of record breaking warm/hot temps.
A cold upper-level trough moves overhead Tuesday/Wednesday this week
Then by the weekend it’s over Idaho, bringing beneficial showers to eastern Oregon and that state. But that doesn’t leave much rain west of the Cascades.
By the middle of next week (10 days away), the troughing is much weaker and we should be mainly or all dry.
How much rain? All models agree we don’t get a big soaking from those cool showers this week. GFS here shows only 1/4 to 1/2″ at best. That’ll keep fire danger low, but barely penetrate into the top of our soil.
15 day forecast from ECMWF ensembles show the drought conditions continuing. An inch or less the rest of the month west of the Cascades.
I am more concerned now compared to 3 weeks ago when I said it wasn’t time to panic…yet. Hopefully a pattern change shows up at the end of the month or early June.
Chief Meteorologist Mark Nelsen