No Snow for NW Washington Sunday morning :(

No Snow for NW Washington Sunday morning :(

This will be a brief post, I just wanted to let folks know that our chances of snow for San Juan/Whatcom Counties Sunday morning have dramatically decreased due to our shortwave taking a more southerly track. Compare tonight’s run to last night’s run and notice how far south the low has shifted. As a result, we won’t have the combination of near-freezing temperatures and moisture necessary for sea-level snowfall.

Last night’s run:

Sea-level-pressure, 10-meter winds, and 925 mb temperatures at 11:00 am PST, Sun 11 Feb 2018
Sea-level-pressure, 10-meter winds, and 925 mb temperatures at 11:00 am PST, Sun 11 Feb 2018
Credit: UW Atmospheric Sciences

Tonight’s run:

Sea-level-pressure, 10-meter winds, and 925 mb temperatures at 11:00 am PST, Sun 11 Feb 2018
Sea-level-pressure, 10-meter winds, and 925 mb temperatures at 11:00 am PST, Sun 11 Feb 2018
Credit: UW Atmospheric Sciences

There is still a slight chance that some places along the Olympic Peninsula above 500 feet may see a rain-snow mix or even 0.1 to 0.2 inches of snow. Both Portland and Seattle should remain completely dry, so there’s no chance of snow there. As you can tell, I’m really grasping at straws here!

3-hour precip/snow ending 7 am Sunday 2/11/2018
3-hour precip/snow ending 7 am Sunday 2/11/2018
Credit: University of Washington

This system will usher in another shot of cool air, and temperatures should drop below freezing in both Seattle and Portland Monday morning. Although it’s not a given, this could be the last frost of the 2017-2018 winter, so savor it or celebrate its passing (whichever you prefer!).

Sea-level-pressure, 10-meter winds, and 925 mb temperatures at 07:00 am PST, Mon 12 Feb 2018
Sea-level-pressure, 10-meter winds, and 925 mb temperatures at 07:00 am PST, Mon 12 Feb 2018
Credit: UW Atmospheric Sciences

Next week, we’ll have a large ridge over the NE Pacific and weak NW flow over us, giving us extremely weak systems that will increase cloud cover but not much else. The image below shows a weak shortwave passing through on Wednesday, and we’re expected to have even weaker ones Thursday and Friday night.


Temperatures should remain near average during this time, and folks closer to the Washington/BC border have the best chance of seeing some light sprinkles with these systems. Portland is expected to remain dry at this time, but a slight southward perturbation of any shortwave could result in (gasp!) a couple hundredths of an inch of rain in the metro area.

Have a great Sunday, and thanks for reading!
Charlie

 

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