Funnel Cloud in the Lowlands and Substational Snow in the Mountains

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!

Hurricane Ridge on the Olympic Mountains (around 5200 ft).  Beautiful

Even the relatively low elevation of Stevens Pass (around 4000 ft) received significant snowfall.

All of this white bounty is the result of very cold, unstable air moving into our region, which is illustrated by the visible satellite image this morning (below). 

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.

Snow in the Mountains and Wet

The rapid transition to cool, wet conditions occurred yesterday, with temperatures in Seattle declining from 80F on Tuesday to 58F in Wednesday.   Major cooling.

Cool and wet enough so that substantial snow fell above 5000 ft (see Paradise and Crystal Mountain cam imagery below).

During the past 48 hrs, there have been large amounts of precipitation in the Cascades, with one location near the Spada Lake reservoir getting almost 4 inches!  Lots of precipitation to moisten the crops in eastern Washington.

The cool/wet weather is not over.  A very potent front is now approaching our coast (see current satellite image below).  Cold/unstable air is behind it (area with clouds and openings on the left side of the image).

Below is the forecast precipitation total through Sunday morning.  

Substantial amounts (1-4 inches) on the western side of the Cascades and near the crest.  Substantial amounts on the SW side of the Olympics.

Temperatures will be low enough that substantial snowfall will occur above 5000 ft (see below).

This precipitation is very well timed and will push up river levels on the eastern side of the Cascades, which have been lagging due to below-normal snowpack (see below for the Yakima River)

The fact that the Yakima Reservoirs are now full and will remain full for the next several weeks bodes well for the water supply this summer.