Drought and fire weather concerns aside, this has been an amazing stretch of summer weather…in mid-April! Today we made it to 78 degrees in Portland; similar to an early July day
Think back…how many times can you recall waking up to sunshine for 11 consecutive days? It’s nothing unusual if you live east of the Cascades of course (drier climate). But west of the mountains, even in summer, it’s rare. From fall through spring it doesn’t happen because we have weather systems moving through from time to time. In July and August we get occasional surges of cooler marine air and low clouds. So even in the peak of summer we typically don’t see more than 7 cloudless days. Sure, we’ve seen some high clouds a couple mornings recently, but no significant cloud cover since Saturday the 10th! I don’t have stats for cloud cover, but I think it’s quite likely we haven’t seen this in April in a long time!
Today is the 8th consecutive 70 degree day in Portland.
This is the longest stretch in the 70s ever observed here in April. Those records go back to 1940.
We set one record high for the date last Saturday, but no other warm temperature records. In fact, as of this moment it’s just the 13th warmest April on record; well below 2016, 2004, and just last year. It’s probably fair to assume the ranking will drop once we hit the cool/showery weather this weekend. So it’s not a spectacularly warm April, but consistently warm. I’ve never seen such a long stretch of offshore flow and extremely low humidity in March or April. Probably not in May either. Dewpoints have regularly been in the 30s, or even 20s for multiple days. The woods around my house are as dry/crunchy as mid-summer after repeated bouts of the dry easterly wind. I’ve watered my deck pots several times over the past week or so. Luckily much of the Cascades remains under at least some snowpack and we still have the subsoil wet from winter rains.
So dry…only 2 days with measurable rain in the first three weeks of the month. So far, just .09″ rain this month.
Of course we can easily get 1-2″ rain in a week this time of year so don’t assume it’s going to be any sort of record dry April.
An upper-level trough will move through the Pacific Northwest this weekend, with the first rain arriving Friday evening (late). You can see the well below average heights in the atmosphere on the Sunday ECMWF ensemble 500mb chart. This screams cold showers, maybe hail and thunder too.
By the middle of next week, a (transitory) upper-level ridge is overhead, cutting off the rain again. More rain should return the latter half of next week as April wraps up.
On the ECMWF 24 hour precipitation ensemble chart, you see the solid chance for a soaking rain this weekend, but plenty of gaps the middle of next week (Tuesday/Wednesday). Then more widespread rain again later in the week. Each horizontal line is one individual ensemble member. On a side note, these ensembles are run at a lower resolution than the “operational” ECMWF run, but about a year from now the resolution will be upgraded significantly.
The GEFS (GFS ensembles) are similar
Could we see an inch or more in the lowest/driest areas west of the Cascades before the month wraps up? Possibly. Both the GEFS & EPS are showing 1-2″ in the last 7 days of the month in the lowlands with 2″ or more in the foothills and Cascades/Coast Range
So I wouldn’t be surprised if we end up with a drier than average April, but it’s unlikely we’ll see a record dry month. Let’s hope for a soaking at some point in May!
Chief Meteorologist Mark Nelsen