Making its entrance today into the Pac NW is the first stage of that MASSIVE trough, foretold long ago by your NOAA spaghetti factory to begin happening about now, and peak out between May 25th-26th.
Now you’ll understand why, if you want to get a handle on the exceptional things that might be in the weather pipeline, you have to have some spaghetti every day. (Note: right now, 5:10 AM, the “factory” is down, has a bug in the sofware that REALLY makes it look like “spaghetti” because too many lines are shown. Its kind of a hoot. I will have to inform NOAA again, as I did a few days ago, or maybe you can, that something is wrong. Their answer to me back then was that they had not yet noticed the problem; made me think I was the ONLY one looking at them, also funny!) It is a powerful tool, one that also foretold the excessive heat we are experiencing today–recall the “June in May” writeup based completely on spaghetti.
That second pulse of cold air aloft, the one shown below in the forecast map for the afternoon of May 25th (upper left panel) over Reno, NV, is REMARKABLY strong for this time of year, and will bring exceptionally low snow levels to northern and central California for later May.
And look at how much the surface map (upper right hand panel) is in a dither with the circulation around the low pressure at the surface extending all the way from Illinois to California! Its HUGE!
But what about us? What does all this atmo commotion mean for you and me?
Briefly, just Dust in the Wind, to allude to an old, sweet song by that heavy metal, huge hair group, Kansas, that hit the scene in the 1970s and were quite something I thought. Yep, the dryness in this HUGE trough makes me as sad as their song does about being only a spec of dirt.
Look at the lower left hand panel in the forecast chart below to see what the moisture expected at 700 millibars, about 10 k above sea level, or a little above the top of Mt. Sara Lemmon, for the afternoon of May 25th. It’s grim.
As you can see there are two but regions in the SW and West that have moisture at 10 K; that in central and northern California extending northward and expanding eastward, and a TINY stream from the tropics hundreds of miles to the east of us in western Texas.
Thus, there is no HOPE whatsoever of rain in southern Arizona with this huge system, because, like almost all of our cold winter systems, the core of the jet stream at 500 millibars, that band of wind that circumscribes the Pacific moisture over northern Califonia below, NEVER gets here, dammitall!
And those powerful winds around the outside of the trough core, really representing trajectories of subsided air from the cold Pacific, just race around it, preventing an intrusion of tropical air. The normal tendency for upward motion on the EAST side of all troughs trough is totally inadequate to produce clouds and precip with such dry air. About the only thing you could expect to see is a few filaments of rapidly moving CIrrus, maybe a lenticular or two on the 25th-26th, and, after the cool air moves in on the 26th, a couple of Cumulus humilis. And maybe the same kinds of cloud fragments off and on before that. Otherwise, the only “precipitation” will be “lithometeors”, dust particles. I suppose they might add up to an eighth of an inch over several days. Hahahaha.
Sure looks like the Catalina area will be raked with winds above 40 mph in gusts with this system before its over.
Check the excitement at the NWS here in Tucson here.