Ask someone when spring starts and you expect to hear around March 20-22, during the time of the Spring Equinox.
But here in western Washington, the biggest transition generally occurs weeks earlier, generally during the past week in February or the first week of March.
Let me demonstrate this to you.
Consider lowland snow. The figure below shows the daily average (green) and daily extreme (blue) snowfall in Seattle. The red line indicates March 15.
The big stuff is all in January. We have enjoyed as much as 5 inches into early March, but only light snow after the first week of the month.
No snow days after March 7. Sorry kids.
An early March end of snow is also observed in the Tri-Cities (Richland shown below)
What about temperature?
Let's start with the daily averages for mean (brown), lows (blue), and highs (red) at Seattle.
Low temperatures stagnate until about February 20th, after which they steadily rise. The average temperature is similar. The highs start to rise earlier.
Very similar situation at Pasco (below), except the highs really start to rev up in February.
Why? I suspect the substantial decline in low clouds and the increasing solar radiation in February are the explanations.
What about temperature EXTREMES? I have an interesting story for you there.
In the figure below, the red color indicates the daily record highs, and blues the daily record lows.
For Seattle, early February represents the end of really cold temps (15F or less) and after early March, the low 20s are unattainable. In January, highs have never reached the mid-60s but 80F has happened after the Ides of March.
This year the atmosphere seems antsy to go through the spring transition. In Seattle, temperatures will jump into the low to mid-50s by the end of the week.
The icing on the "spring transition" cake will be the beginning of Daily Savings Time on March 9th!
The unbeatable combination of warmth and more evening sun.
While spring is indeed springing: my bluebells, snow drops, trillium and mayapples are already beginning to emerge (even up here in the icebox of the Western Washington lowlands, AKA Bellingham), but these are primarily spring ephemerals that sprout early and wither away in their above-ground parts by summer, any gardener around these parts who's worth his salt knows well that a typical March is still very much wintertime barring an exceptional early spring heatwave.
ReplyDeleteThe current forecast is very wet but not notably warm for midwinter and it appears as though we may see a return of cooler conditions as we progress into early March. We're warming up out of the freezer but that certainly doesn't mean it will be particularly warm and I suspect we may not be charging headlong into spring quite yet.
I just checked the data from my backyard weather station and found that the average temperature (calculated using the values recorded at 5-minute intervals) at my location in Bellingham for 1/17 - 2/15 was a distinctly chilly 31.9F - pretty impressive!
ReplyDeleteGood stuff, thank you. We have had some measurable April snowfalls at Sea-Tac, however, correct?
ReplyDeleteIn late April of 2008, my area (Lake Stevens) got hit with a convergence zone that dropped nearly seven inches of wet snow. The fullest depth of the snow peaked in the morning and by the next day, it had all but melted away.
DeleteThis is interesting, because if there's one thing that's hard to endure around here it's spring. Is there even one? The temperature rises so very slowly. Other parts of the country are drying out in warm sunshine and the temps are shooting up rapidly. Here, we get "June gloom" and temps that barely budge up. In spring we need some warm sun, but we get cold drizzle. On the other hand, the cool days of late autumn can be wonderful.
ReplyDeleteI couldn't disagree more! While we spend the majority of our time here in my native western WA, we're also often in my husband's homeland of central Wisconsin. Talk about no spring! It can be deep into April (or beyond) before things start to green up & spring flowers make a genuine appearance. I grant that June gloom here is a Thing, but in the lead-up to that we have far more spring than many parts of the country!
DeleteI tend to agree somewhat on your question "Is there even one (spring season)"? Of course, there is. But I've wondered myself at times and have considered for more than a decade the period between mid-November through the end of April as one, long winterspring. With the brief, occasional warmer than and colder than periods from winterspring average.
DeleteColleen - you missed my point. In the midwest, sure spring comes later, but when it comes, you know it. When it arrives, things change fast. Here, there's no "switch". It's a very slow change that drags on for months.
DeleteWhat's the old saying around here? There are 2 seasons. Rain, and getting ready to rain.
Spring around here is usually an extension of March like weather except for a couple of weeks of almost summer like weather usually sometime in May until the "June gloom" hits for a couple weeks. Then the summer "drought" comes and as we've all experienced in recent years (and due to climate change), this can be hotter and drier than we are used to. I must say I enjoyed the wet August and September last year for a change!
DeleteThere is no summer drought due to climate change. Ask Cliff to pull up the records (again).
DeleteWhen are we going to finally mature past the climate change drama thing?
You are so incredibly wrong even in northern Washington (bellingham) here the trees turn green in about one week and the leaves grow 1 feet in diameter Native South Dakotan here, it’ll take three months for that ash tree to revive and put out some buds, and mind you we are at 49 latitude
DeleteShorty you have also completely missed the point. I'm not talking about WHEN individual tree leaves come out! Of course that happens later in the northern interior. I'm talking abut the rate and the intensity of seasonal change.
DeleteQuestion.. what do you think about the average person's reading comprehension and critical thinking skills theses days? Do you get the impression they are at an all time low?
They relatively high on this forum Everybody pounced on your initial post for it’s curious assessment of local seasonal changes en masse :)
DeleteShorty, take a little break. Get some fresh air, maybe go for a walk.
DeleteGreat blog Cliff, I remember back in 2008 on May 5th we had 5" of snow just a bit north of Arlington at 400' elevation, as crazy as that happening that late in the spring was watching it all melt the same day
ReplyDeleteI think it's interesting how the low temperature dips slightly during the beginning of February. Is it a case of a few really cold stretches pulling down the average or is there a larger, more stable meteorological force behind it?
ReplyDeleteI'm just speculating but it could be that, during La Nina winters, the phenomenon is in full swing and the typical La Nina pattern peaks around that time (high pressure offshore in the North Pacific and low pressure to our northeast) which often brings us prolonged colder than normal temperatures.
DeleteThanks. I'm also guessing that the probability of a clear, cold night is slightly higher during this part of the winter. December and January have more nights with blanket clouds, while February starts getting more nights with radiational heat loss.
DeleteHumidity is back up to a comfortable level, too. By comparison with last week it feels almost subtropical.
ReplyDeleteHere's hoping it stays cold enough for long enough in the mountains to get the snowpack up to normal levels
ReplyDeleteThose warmer temperatures will be coming with copious amounts of rain in at atmospheric river/pineapple express pattern.
ReplyDeleteMy home state of south dakota has been flirting with 25 below temps. Most of the interior is ine with the north pole now
ReplyDelete