Very active spring weather has been occurring over the Northwest, with substantial snow above 4000 ft and unstable air that has brought heavy showers and even a mini-tornado!
First, the snow. Here is a cam shot this morning at Paradise (Mt. Rainier) at around 5400 ft. Impressive snowfall!
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Hurricane Ridge on the Olympic Mountains (around 5200 ft). Beautiful
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Even the relatively low elevation of Stevens Pass (around 4000 ft) received significant snowfall.
The blue arrow points to the unstable air, characterized by showers and sunbreaks. The instability showers are driven by a large change in temperatures with height, with cold arctic air passing over relatively warm water.
Since current, low-level winds are from the west, there are rainshadow regions downstream of the Olympics and Cascades (areas of lack of clouds are evident there).
Substantial new snow has been falling above 4500 ft, such as at Paradice on Mountain Rainer, where nearly 15 inches have fallen (see below)
Precipitation over the region during the past 48 hr has been substantial, with many locations in the mountains getting 2-3 inches of liquid water (the observations are shown below).
As I have discussed in previous blogs, the claims of extreme drought over the region are inconsistent with the facts on the ground (and in the air). There will be plenty of water this summer for all uses, particularly with the full reservoirs of the region.
Snowpack was low, but substantial, and well-timed total precipitation (which was NOT below normal) ensures that water will not be a problem this summer.
Now for the fun part of the blog.....we had another funnel cloud over Puget Sound....a mini-tornado if you like.
One formed yesterday (Friday) over southwest Seattle around 8 PM. The rotating cloud was captured by Matt Young, a relative of one of my colleagues at the UW.
This weak tornadic event was associated with a modest area of convection (cumulonimbus clouds), which is apparent in the radar image around 8 PM (below).
Funnel clouds associated with weak cumulus convection (produced by unstable air) are not unusual over Puget Sound. There is a lot of horizontal wind shear around here (winds changing rapidly in distance), with wind shear having essential rotation (see schematic below).
The upward motion in convection can "spin up" this rotation into a weak vortex....something I have blogged about many times before.
Puget Sound Convergence Zones are famous for being associated with such weak funnels, something I describe in my Northwest weather book.
Puget Sound is not Oklahoma, where several thunderstorms and tornadoes are frequently threatening. But weak convective funnels occur all the time around the Puget Sound region.
The panic mongerers will find some way to spin this; meanwhile Soil moisture (at 8 in) is 101% of normal, temp at 102 to 96% of normal. An objective person cannot find evidence of drought.
ReplyDeleteBeen quite gusty at times on the southeast side of the Olympics, near the water, with that system pushing through. W…WNW wind sometimes briefly strong. Reminds me a bit of a system we might see during winter. Despite the sun breaks, it’s fairly cold with the wind chill.
ReplyDeleteA few of those convective funnels have made it to ground level...one near the Bremerton area, a few years ago...and I remember one that hit briefly North of the U. District, a long time ago.
ReplyDeleteAre you referring to the tornado that hit Port Orchard back in 2018?
DeleteEven this weak funnel cloud effect we've seen spin our big fir trees back and forth 25 degrees; mother natures weather is very impressive.
ReplyDeleteCliff says “the snowpack is low but substantial”. Five basins in Washington State are at 10% or less of normal. Five more are at 33% or less of normal (Source: Washington Snotel, Snow Water Equivalent as of May 17 end of day). This is not “substantial”. The temperature at Paradise on Mt Rainier are warm this week; that fresh snow won’t last through this week. Of course soil moisture is high now but it won’t be once the snow is all melted out which will be much earlier than “normal”.
ReplyDeleteI did observe quite a big of fresh snow on the north side of the Middle Fork Nooksack valley on Sunday. Continuous snow cover started just below ~4000' and by ~5500', it was knee deep. It should help stave off dry vegetation and fire danger for a while but probably won't be impactful regarding summer water supply as it will likely melt pretty rapidly.
ReplyDeleteIts great to hear that the Nooksak Valley got some snow this late in the season! The North Cascades have seemingly had the greatest fire risk over the past few years. This late season gift might just lower the risk somewhat this year.
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