February 2020: A First Look Ahead To “False Spring Season”

February 2020: A First Look Ahead To “False Spring Season”

Happy February everyone! We just experienced the warmest January in 67 years at PDX airport: 45.8 degrees F, which is more than 4 degrees above normal.  It was also the wettest January in 14 years, with 7.58″ of rain.

February is starting much cooler than January ended.  Instead of 62 degrees, this morning there were spotty snow showers in a few western OR-WA locations, including Molalla. (Credit: post by Jeff Roth on Facebook).  There may or may not be more mixed showers this evening, but tonight looks chilly & frosty once again.

Looking ahead…this is the time of year that our daylight and sun angle start to ramp up dramatically.  It’s not really spring yet, but sometimes we get a taste of the coming spring later in the month.

Shadows were very visible on this Groundhog Day morning in east Portland, suggesting that winter is going to hang on for a while this year.  But what do the long-range maps show?

The CPC’s 6-10 day map looks pretty ambivalent for the Western U.S. on temps; just  a little chilly over the central Rockies.

 

 

But it does show a good chance for drier-than-normal conditions along the west coast, especially in California:

Credit to cpc.ncep.noaa.gov

 

Normally I don’t like to post the 8-14 day maps due to the greater uncertainty involved.  But it’s Groundhog Day and we want to know about false spring, and mid-February is when the sun angle begins to make a real difference.  So here is the February 9-15 period:

The West Coast is still dry, but not warm! This pattern is synonymous with a “trough” in the jet stream, centered over Wyoming and Utah.  Most likely there would be an upper level ridge in the Eastern Pacific…but in this instance it’s not close enough to pump any warm air into our region.

Depending how you look at it, this could give us the shot for a late-season arctic blast, or at least a significant cold snap east of the Cascades.  Or it could just be cool and mostly dry, perhaps with a chilly north or east wind.  We would need the upper ridge to move closer to us at some point, in order to see anything remotely spring-like with our temps.

It’s definitely not entirely out-of-the-ordinary, for a dry pattern to start with chilly north/east flow, only to see milder air move in a few days later.  Once you get past Valentine’s Day, it’s pretty easy for PDX to hit 60 degrees if sunshine and mild 850mb conditions join forces at some point.

I’m not saying it will happen later this month. But if it does,  it’s much better to wait until the last 7-10 days of February.  That puts us in a position to reach 65 in the western lowlands.

 

Enjoy the Bowl game this afternoon! -Karl

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