CONTINUED FROM YESTERDAY…
Now that we have a loose grip on some of the variables that make our weather,let’s go a little more in depth before confronting EL NINO.
As the Earth tries to attain equilibrium, one of the larger drivers of the process, atmospherically, (remember, atmosphere ocean and land are all inter-connected players) is the Hadley Cell.
These occur in the inter-tropical convergence zone, just N. of the equator extending N. 10 degrees of latitude or so over the ocean.Think of the rotation of a cyclone, but clockwise, and not horizontal in nature, but vertically oriented. The up side by the equator, rising with entrained moisture & hot air , then being spun N. as condensation and cooling occur and descending back to the surface. These cells move vast amounts of heat and moisture northward where the jet stream can capture it and move it farther north and east.
Now here is the thing about that – EL NINO!
El Nino is defined as an increase of at least a half degree of Sea Surface Temperatures,(SST) in the east Pacific basin for at least five, three month,overlapping periods.
As of today SSTs are 1.5 to 2.2 degrees above norms.
As this is well above threshold, it is forecast to last into the spring, and possibly beyond.
This means greater evaporative moisture content in the atmosphere being carried N. and East by the Hadley cells into N. America.
The fly in the ointment is the Northern hemisphere jet stream track – there are two. The northern branch brings cold air from the arctic south into north america- think arctic clipper of the last two winters.
The southern branch carries the sub tropical moisture north into SW North America. Both are important for El Nino impact.
If the two bring air masses inland and collide – then storm dynamics increase exponentially.
It seems more than likely that a strong El Nino is in play for this winter.Interaction of the two Jet Streams will determine storm tracks and precipitation.
Unfortunately, we have little skill at predicting those tracks.
As two jets affect weather patterns over N America, their interaction is crucial to predicting storm tracks. Rossby Waves influence the undulations, hemispherically, of the Jet Stream tracks, are poorly understood.They are influenced by the rotation of the Earth, as well as ALL of the afore mentioned factors: i.e. land mass, ocean temperature,atmospheric moisture content,temperature, to name a few.
Most people are aware of them, due to traveling by Jet at 30,000 plus feet ASl.
However they are neither static in length, altitude,duration, speed
or location.Pretty much like all things weather related, the whole system is in a constant state of flux.
So if the stars align, the likely El Nino stays strong, the jets co-operate, low pressure systems play nice…
It will be a good year for fat skis!