Very Active Pacific Weather Pattern

A couple of unusually strong storms are headed for the Sierra that will bring upper elevation snow, high winds and cooler temperatures.

The first storm will come in late Sunday afternoon. Storms this time of year do not pack much moisture. I doubt any moisture associated with Sunday's storm will make it over the Carson range. But the cold air and wind certainly will.

Here is a 500mb look at the Pacific ocean.

First thing to notice, our ridge of high pressure has been pushed out to sea again. Second thing to notice, the storm track is very active, with storms somewhat stacked up. If this were late December, it would be quite impressive. Again, I do not see copious amounts of precip, but I do see much cooler and more windy weather for Tahoe and the Sierra through at least next Saturday (and Reno/Carson too).

Paul Hunnington, the top researcher at TWB and maybe the top researcher anywhere, makes this observation:

What is happening is the North Atlantic Oscillation is locked in negative phase which means the Azores high is extremely abnormally weak for this time of year and the butterfly effect is keeping the jet stream or North America pattern in positive phase. This means the jet stream is finding an equilibrium at a low el nino type angular trajectory and is being fueled by high humidity and cloud development over east asia. Moreover with the north pacific decadel in warm phase (Northeast pacific basin sea surface temperatures are above normal) it is energizing the large upper level lows that are slowly drifting east across the north pacific ocean and rotating over the West coast every five days or so. Another interesting teleconnective pattern is the Antarctic Oscillation and the positive phase that is becoming more common as our earth warms! The positive phase controls the lows from detracting from the polar vortex and dropping down into the lower latitudes and during the last thirty years is becoming more of the norm and thus keeps a zonal jet stream that hugs the ice shelf. What does this have to do with California weather patterns one might ask? To be honest no one knows but could mean more active wet summers for us??  Bottom line is negative phase North Atlantic Oscillation+positive phase North Pacific decadel oscillation+active equatorial thunderstorms or hyperactive ITCZ+ high global specific humidity levels (result of two el nino years)= large upper levels lows at low latitudes hitting the west coast most if not all summer! This is why I was predicting snow around summer solstice.

Yes, we are thinking high elevation snow for Sunday night and then again next Thursday.

We are also thinking that this pattern bodes well for an even stormier winter starting in late October or early November. Maybe not Donner like, but more than last year! We will have a much more detailed explanation sometime this summer.

Stay Tuned ...


  1. This comment has been removed by the author.

  2. Would our monsoons seasons be more active to. Is it good news that we could have rain almost all year around.would winter be more active.

    1. I am guessing that the monsoon season would stay pretty constant. However, these larger storms we are seeing late in the year will have the tendency to pull that moisture further north and west.

  3. That's a great question Shawn and what i'm observing is the east equatorial pacific is staying rather warm around the slim tongue of colder water ( La Nina) that has surfaced behind the massive kelvin wave that propagated eastward last spring and summer triggering the hyped up "super el nino"! The pattern now is much different than 1998(last similar post el nino year) in many ways regarding how these oceanic sea surface temperatures are counter reacting to these incredibly high equatorial ocean temperatures that peaked in November if i recall? Presently the warm sst anomalies are still dominating a large portion of the east equatorial pacific and most of the Northeast Pacific ocean basin from Baja up to Alaska and out to around Hawaii. This should create ripe conditions for strong thunderstorms to form in the east equatorial pacific above the colder water and be entrained into the upper level lows that are lining up around the entire northern hemispheric westerlies. This should give these large troughs better dynamics for thunderstorms development and wetting rains. Late August i am predicting a major record breaking heatwave that could bring a very dangerous lightning monsoon based storm that could trigger many fires and put people outdoors (hikers, boaters, golfers, etc in danger). There will be some before than but the real fireworks come late summer. cheers to a cloudy world right now, paul huntington

  4. This comment has been removed by the author.

  5. Lets hope the thunderstorms produce just enough rain to ease the fire danger.

  6. Might be a bit to early but what are the thought for La Nina? What are some thoughts for next winter? Are we looking at another dry winter?


Post a Comment