The Great Portland/SW Washington Snowstorm of April 11, 2022

 Portland residents will be telling their grandchildren about this one.

The great Portland April snowstorm.

The latest NOAA/HRRR forecast shows bountiful snowfall over the lowlands of SW Washington and NW Oregon for the 24 h ending 5 PM Monday, with several inches around Portland.    A drive down I-5 tomorrow morning may be exciting.  A drive through the Gorge could be dangerous.  And the southern Cascades will be hit hard.


The even higher resolution UW forecast model has a similar solution (see below)


This snow is very welcome, considering that the Oregon snowpack is currently below normal.  A late-season snow blast has a major impact on fire season.

Why this extraordinarily late cold/snow event?

We start with a very deep upper-level trough (see the forecast for 5 AM Monday below for 500 hPa...about 18,000 ft).  Very impressive.


And this trough induces a deep low center (see the surface forecast for the same time), which draws in cold air from the north.  In addition, heavy precipitation from this system will cause the atmosphere to cool by evaporation and through melting of snow falling in from above.


Anyway, a bit of  Northwest weather history will be made tomorrow.

Want to learn more about northwest weather? Sign up on Patreon to join my monthly weather discussions. Click the button below to get started. 

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