Wheres spring? Good question.
It's been a rough April if you like warmer weather, no ifs ands or buts about it.
ABOVE: forecast high temperatures Monday, April 25th through Tuesday, May 10th
Monday will be just several degrees from a record cold high temperature but then we do make progress closer toward normal. It's worth noting that, especially this time of year the normal range is more appropriate than a fixed number. Here I've plotted my forecast along with the normal range of high temperatures (+/- 1 standard deviation: which means 68% of the recored highs fall within that range). The lower and higher end range are a thin, light gray dashed line with the average in orange.
You can see that except for Monday we're still within the 'normal range' but definitely & consistently on the colder side of the range.
I keep reminding people that yes it's a cold April but we're still BY FAR in a heat surplus after our 4th warmest Autumn last year, the hottest summer and the 5th hottest year ever in 2021.
It's been cold, yes but who's to blame? The overall pattern and the (normal) dissolution of the annual winter polar vortex. The cold collapses every spring but usually it's dispersed evenly (in theory) through North America, Europe and Asia- but if you have a 'stuck' pattern like we do this spring, it's funneled more in one spot than another...and you guessed it: that's US!
This is a view of the overall April (upper atmospheric or flow) pattern. Yellow/orange roughly translates to warmer conditions and blue; colder.
Two areas stand out: two fingers of yellow/orange that push north into Greenland and then one that pushes out of Siberia toward the North Pole. These anomalies have pushed cold into northwestern North America through eastern Alaska and then that cold air is forced in our direction as it hits the wall that is the Canadian Rockies. This pattern is partly to blame on La Nina this season but also, some research shows Autumn temperature and snowfall conditions in Siberia.
This is a look at 30 day temperature anomalies (departure from the normal). This pattern looks similar, just rougher to the one above.
You'll see I've circled the three numbers in the lower right on this image. They are the maximum, minimum and average temperature anomalies for the whole northern hemisphere. Note that the warmest warms are higher than the coldest colds and that the net average is 0.596 degrees for the hemisphere (which is a lot).
For reference, because it's easy to only think locally and not big picture... here's let June/July across the hemisphere:
Why do I post this? Because note the numbers at the bottom. The hemisphere was 'only' +0.476 degrees above normal (still a lot but less than the past 30 days). The point being: we were SCORCHING early last summer and in the Pacific Northwest- so we thought it was super hot, which of course it was... but while we're COLD this spring and it can be easy to forget how hot things are, big picture... much of the arctic, Siberia and Russia are seeing VERY warm springs.
I end with the trends. While the first 1/3 of May looks cooler than normal, it's not by as much as April has been an the gap between our temperatures (at least forecasted) and normal closes toward May 10th. The forecast trend is the red long arrow while the blue line is the forecast and the orange is the normal high.
It's worth remaining everyone that April 2018 was our coldest ever April followed by the 7th hottest May (remember we hit 100 degrees!?).. so the first half of spring means NOTHING about the rest of spring and certainly not summer. I have a sneaky feeling we'll see an abrupt turn around to hot weather... so if you don't like that... savor the cold while you have it.
-Meteorologist, Sven Sundgaard
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