It doesn’t get any better for a desert in southeast Arizona than this; a model run with NINE panels of rain, including rain on Christmas morning, and here they are from last night’s 5 PM AST global data, our best computers in action. Remember the bad old days just a few weeks ago when no rain was foretold in the models for 15 days ahead, and that dry forecast was seen day after day for another 15 days?
Those days are gone. The “mean”, as in average position of, mean (as in bad, angry weather) trough is here now. You are in it. You can’t escape. “Trough bowl” in progress!” We’re going “weather bowling”! OK, enough exclamatory statements. This doesn’t mean every day is bad, but storm days will keep recurring beginning next Friday.
Here are a couple of those forecast panels from last evening, the first for Friday’s major rain about which a news release was released. This is so great. What’s even greater is that the Canadians, with their more accurate model, are on board for a big Friday rain, too! Two models with rain, as we know, guarantee a rain!
Here’s another one on Christmas Day (left out some other rain days):
Storms will be dropping like bowling balls, one after another, like down a water slide, moving southeastward every few days out of the Pacific over the next two weeks, likely longer since once patterns get established they persist. In fact, “persistence” is one of our greatest forecast techniques, just saying what’s already been (say, cold and wet), will be what’s ahead. Its great!
An example of how you could have become quite the neighborhood weather guru last October and November. As a cloud maven junior, you would have already gained some prestige in your neighborhood. Now imagine adding to that status if your neighbors had come up to you in October at some point and asked about the winter. You would ONLY have had to have known about the weather you had already had for the past week or so to state, with furrowed brow, “I foresee much the same weather OVERALL as we’re having for the next two weeks, maybe a month” to your neighbors! And the majority of the time, you would be right! Think of all the right forecasts you would have made day after day in October, November, into early December!
This is because, as all weathermen and weatherwomen know, the jet stream and the storms it carries gets stuck in groves like the water in rivers for weeks at a time; but then suddenly jumps the banks into a new pattern. So, using retrospective forecasting techniques, your going to be right a majority of the time. To paraphrase so many internet ads, “this is a little known secret that weather forecasters don’t want you to know.”
But today you’d be so WRONG with that retrospective forecast technique! Change happens.
The “stream” is “jumping the banks” right now–some kind of tipping point has been reached somewhere and the new, cold and wet pattern is about to begin in the West, its just ahead beginning with that big rain here on Friday into Saturday.
But how do you know that one storm is the beginning of many, not just a breakthrough fluke in a continuing dry pattern? Confidence is added by having some spaghetti, not just examining the many panels of rain. Here, 10 days out, we are in the trough bowl! Little doubt about it; count on it.
And because our rains are associated with cold air invasions, there’ll be snow birds heading back to Illinois and Wisconsin pretty soon, wondering why they came to Arizona. Of course, the ski birds will be quite happy with the pile up on top of Ms. Mt. Lemmon.
What’s the real unknown here?
How much precip will our cold wet regime really bring? While we’ll have a number of opportunities for drought denting storms, they could also be a stream of minimal, relatively inconsequential ones. That’s the real bugaboo here in this monumental pattern change. The exact trajectories the storms take is going to be pretty unknown today. We could end up with frequent storms and cold days, but only average rainfall or even a little below after two weeks. Or, as in the first slug on Friday and Saturday, a total in one 24 h period that gives the December amount into respectable levels just by itself.
C-M has a gut feeling that we will see above average rains here over the next 30 days (two inches or more). “Gut feelings” are pretty worthless, but, there you have it.
Remember our logo, “Right or wrong, you heard it here FIRST!” :}