Wipha, Chinook, and The Pineapple Express


So, while getting a haircut on Monday, my barber was throwing out these crazy words and concepts to me.  To be honest, I heard those names before, but as this guy was explaining them to me (read as: wouldn’t shut up as he cut my hair) I realized I knew what he was talking about, I just didn’t expect him to use such strange names to describe them.  So I decided to check his facts by the only way I seem to want to check facts anymore … searching Wikipedia.  As it turns out, he was right, and the words he used were correct, and most of all the whole topic became kind of cool.

Let me start with warning you … the topic is on one that may have come up in the past here.  Okay, it comes up all the time.  It’s about the weather.  The last week, Anchorage has had unseasonably warm conditions for Mid-October.  Usually, the temperature walks the freezing line, and we would get rain/snow/sleet mixes on the verge of full-on winter.  This last week, it’s been mostly overcast but warm — over 60°F (15°C).  We’ve had some rain to go along with it, and high winds, but less rain than you would expect from these overcast skies.  It’s caused by a double whammy of a weather problem.

First of all — there is the Pineapple Express (no, not the crappy Seth Rogen pot movie; an actual weather thing).  There is a high pressure thingy in the northern Pacific, making the jet stream run across the Hawaiian Islands before cutting north before hitting the Pacific Northwest of North America.  It’s picking up loads of warm air and moisture down there, so when it comes up our way and things start to cool off, water comes gushing out of the clouds.  Deep into winter, Pineapple Expresses can dump feet of heavy moisture rich snow which melts quickly due to the warm air that comes along with it.  While that doesn’t sound like what we are getting, it’s about where it ends up.

This Pineapple Express follows a pattern where it is running up the western side of the Rocky Mountains in western Canada, until it reaches a massive fishhook of mountains in Prince Edward Sound.  Blocked to the south by the Kenai Mountains on the Kenai Peninsula , the warm moist air has no choice but to attempt to go over the Chugach Mountains.  As it does so, all that air gets compressed upwards into a higher pressure bubble.  That high pressure bubble tries to reduces its pressure by doing two things: 1) dumps all it’s water, causing rain/snow at higher elevation; 2) makes the warm air even warmer.  One it gets over the mountain top, the warm dry air rushes down the mountain on the other side.  During winter months, this will melt and evaporate snow faster than you drop a hat.  Since there is no snow to melt right now, we just get the nice effect of windy warm weather.  This whole process of the wind coming down the mountain like that is called a “Chinook“, and is something that can happen in the Western states & Canada too — even as far east as Denver.

But the warm dry air won’t last very long.  This weekend we are going to get one more weirdly named visitor.  Whipa.  Short for Typhoon Whipa.  Typhoons, of course, are the Asian name for hurricanes.  While Whipa won’t be that strong when she reaches us, it will mean warm rainy weather for a few days until it peters out.

So, we get the last few days of “Not Winter”, and if this keeps up, we may even make it through half of Autumn while feeling Autumn.  But who knows, there could be another funny name of something that comes along before then.


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