We look to the heavens and ask: Why do we suffer? Why is the warmth of summer denied us?
Is this a great test of a stormy Satan? If we accept the coolness and clouds without complaint, will the warmth of a true summer be restored, as Job was restored when he accepted God's will without complaint?
Verily, we have not acted like Job. We torture ourselves counting the minutes of warmth (Sistek blog here). Headlines in our papers promise greenhouse-induced heat(Seattle Times) and its manifestation is like a ghost. National Weather Service forecasts suggest coolness will end next week, but the heat disappears like the water-on-the-road mirage on a heated road. Blogs, comments, and articles in all sorts of media complain and protest. Cold-hearted Satan is smiling.
But redemption is possible. Perhaps, armed with a better understanding of what is occurring, we can accept our fate, and with our complaints silenced, warm weather will be our just reward.
So why have we been stuck in such a cold pattern? In fact, the atmosphere has been "frozen" in a certain configuration since late winter, causing the heavy snowpack in the mountains as well as cooler than normal and cloudier than normal conditions. Here is a classic example from last weekend:
This figure shows the heights of the 500 mb pressure surface...roughly half way up in the atmosphere. Where the lines extend northward there is a ridge, southward, a trough. Red and yellow colors indicate low heights.
You notice a big ridge over the eastern Pacific, a trough over the northwest and adjacent coastal waters, and a ridge over the central U.S. The atmospheric circulations are wave-like with typical wavelengths of several thousand km, so a ridge over the eastern Pacific is often associated with a rough over the West Coast, and a ridge over the central/eastern U.S. So our cool weather and their heat wave/droughts are intimately connected.
Now one reason that we have had this pattern is because of the La Nina of last year, which is associated with colder than normal temperatures over the tropical waters of the central and eastern Pacific. La Ninas cause tropical convection (thunderstorms) to shift eastward and the easterly trade winds to strengthen. Why do we care about this? Because the shift of the convection perturbs the entire atmosphere-- think of a pond and you throw in a rock...there are waves in the pond. Our pond is the earth's atmosphere and the rock is the thunderstorms; shifting where the rock hits (which the big thunderstorms are) changes the waves that are moving out into the entire atmosphere.
Anyway, a number of research studies and lots of experience has shown that the La Nina shifting of the thunderstorms sets up the upper level pattern shown above, with the cold trough over us. Here is an example:
The La Nina has weakened during the past few months, with the sea surface temperatures in the tropical Pacific nearly normal (a "neutral" situation). But the thunderstorms and the trade winds are still in a La Nina-like configuration and this may be keeping the midlatitude pattern we so hate in place. But what is causing the thunderstorms and trade winds to stay in the La Ninaesque pattern? And could other factors be keeping us in this particular configuration. We do not know. At least I don't know!
Right now the computer models suggest a partial break over the weekend and back into the murk next week, but it is too soon to be sure about any of it.
Perhaps knowing a little more of what is happening will give us the patience of Job.
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