December 2015 Backpacker Alert: Central-West Pacific Conditions Change


Alex Wierbinski's picture

By Alex Wierbinski - Posted on 11 December 2015

FORCES at PLAY 

1> Spin and Cold of the Arctic Circle

 2>  Central and North-East Pacific High Pressure Zone

 3>  Location of Fierce El Nino Waters and Thunderstorms

 

Results So Far

1> Weak Arctic: Low pressure zones are meandering around the Bearing Straight and Gulf of Alaska. Arctic has not chilled down fiercly and spun-up. It's weak.

 2>  Persistant High Pressure Zones forming off California Coast, deflecting El Nino enhanced Tropical Flows to our North, especially from Portland to Seattle. Low pressure zones in the North and Northeast Pacific are meandering, rather than getting fired-up and propelled by Arctic chill and spin. Weak.

 3>  El Nino Boiling along at record level. Its intense tropical flows are riding the front lines running between the meandering lows to the North, in the Gulf of Alaska, and the persistant highs off the California Coast. Very Strong.

Vast tropical flows out of the Pacific Equatorial Zone have been drawn between  the counter-clockwise motion of the weak lows in the Gulf of Alaska and the clockwise flow the the highs off the California Coast cross the West Coast of the USA between Portland Oregon and Seattle Washington. So far.

It's this particular alignment of these specific factors that have been driving  tropical flows of moisture generated by El Nino tropical storms a

 

Evolution of Pattern

The majority of El Nino tropical moisture has been deflected around the Sierra, yet sufficient snowfall has fallen in the Sierra to open the ski resorts.

On December 10th a fierce thunderstorm formed North of Indonisia. This location is optimally lined-up to pump tropical moisture towards the center of California, and the very formation and operation of these epic thunderstorms themselves generates winds pointing at California.

The main factor determining where these powerful winds carrying massive amounts of tropical moisture go is being determined by the shape of high atmospheric pressure zones building and persisting off the California Coast. All through Fall and approaching Winter.

 So far it is these pressure patterns determining if these vast flows of tropical moisture get to the Sierra, to Portland and points North, or passes South around the Sierra across Southern California and into Arizona is determined by the shape of atmospheric pressures off the California Coast.

El Nino tropical mositure will flow around us to the North If the persistant high pressure zones we have seen off the California Coast so far this year continue. If the pressure goes low the tropical moisture will pass to our South.

Neutral conditons should see the Sierra packed with snow, and the lowlands flooded.

 

Any way this works out the middle of the US is going to get pounded...


 

Potential Outcomes

Feast or Famine

 

Resources

High Sierra Backpacker's Weather Page

 

 The text above was finished and represents observations as of
December 18, 2015.

NEXT BACKPACKER ALERT
TRACKING THE SKY
JANUARY 1, 2016

 

 LAST BACKPACKER ALERT
  TRACKING THE SKY
SEPTEMBER 13, 2015

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