Late week warm-up

Dec. 9, 2014-

Now that the wintry mess from Monday is out of the way, we can look forward to plenty of quiet weather this week, with a late week warm-up that will put us close to 50 degrees.  We can thank something called the ‘Pineapple Express’ for the warmer weekend weather.

The Pineapple Express is a strong, deep, and persistent river of moisture that develops from the tropics of the Pacific Ocean to the West Coast of the U.S.  The pineapple part is a tribute to the Hawaiian Islands that the river of atmospheric moisture usually develops near.  This wet pattern can produce flooding rains for the western states.

Storms storms and heavy rain will pummel the West Coast (note the bright white clouds- there is a lot of moisture coming in with those storms).

Storms storms and heavy rain will pummel the West Coast (note the bright white clouds there is a lot of moisture coming in with those storms).

Strong and persistent jet stream winds pick up the moisture and deposit it on our western shores, resulting in torrential rain.  In this week’s case, a strong wind storm will slam Washington along with the rain.  Up to 9″ of rain and several feet of mountain snow will fall over the next 3 days in some spots of northern California.  Californians won’t mind the rain too much, as they are in the midst of a historic drought.

The Pineapple Express drives soggy weather onto the West Coast, and indirectly warms up the Midwest

The Pineapple Express drives soggy weather onto the West Coast, and indirectly warms up the Midwest

So what does this all mean for us? To tie this all together, the strong jet stream winds digging into the West Coast are going to push the jet over the Midwest north (like taking a jump rope, having someone else hold the other end, and whipping a wave through it). This will allow unseasonably warm air to rush into the middle of the country, giving us a dose of near-50 degree weather for the weekend.

Now, eventually the storms moving in on the Express will reach the Midwest and drag cold air back in from Canada, but at least for now we get to benefit from the soggy weather out west of a mild warm-up ourselves.  Enjoy it this weekend!

-Alex

 

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Posted under weather

This post was written by Alex Kirchner on December 9, 2014

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