Honestly, I gave up on the chance of rain overnight into this morning at sunset yesterday due to the absolutely clear skies. And, like you, woke up to not one cloud within a 100 miles! How could this be, given the synoptic situation? Started slicing apples for some humble pie, but then, when looking at a radar and cloud loop (this one from IPS MeteoStar) saw that lower clouds had magically erupted to our west before midnight, and by the time they got here in the early morning hours, had little showers coming out of them!
I did not park my own dusty car out from the carport, either. I thought I would at LEAST see a pile of clouds on Ms. Lemmon, too, this morning! Sure wrong there. Here are a couple of images from what has to be considered a tiny weather miracle:
Chances of rain increasing (imagine!), for just over a week from now as actual model outputs begin reflecting what spaghetti (the many outputs) was indicating, i.e., a big upper trough in the West-Great Basin area. At the time that spaghetti was indicating that, the actual model outputs were not, indicating that they were outliers.
Check this out from last night. Since this model output is more in agreement with that crazy spaghetti plot, it inherently has more credibility, and is likely not an outlier model run. That what the NOAA spaghetti factory is used for, getting a handle on those runs that might be wild, and those that are more likely to verify.
Its valid on the morning of May 8th and shows a trough coming out of the Pacific ahead of the one from the Pac NW, shown at this time over northern Cal. The hope here would be that the one from the SW would have a generous amount of sub-tropical clouds with rain in them.
Cloud shots will be posted later this morning of the next day….. (i didn’t get to is as I had planned)
Yesterday afternoon, the 29th. Here’s what shallow, icy clouds look like, reflecting the unusually cold air above us.
PS: Chance of rain still holding for the 8th. See below for new depiction of big “cutoff” vortex over AZ from last evening’s model run:
The orangy colors denote the strongest winds in “Jetty Jetstream”, and as you know, the colder, low clouds, ones capable of reaching the temperatures where ice forms, are contained within that ring of strongest winds at this level (500 mb). So, while the models I have looked at so far have no rain here, I think there’s a pretty good chance of a rogue shower tomorrow morning anyway. At least there should be some nice Stratocumulus/Cumulus tomorrow and some will have ice in them. As you know, it’ll be awful windy today, too, maybe 40 mph or so in brief gusts here in The Heights of Sutherland.
Also will be looking for some nice lenticulars since “Jetty” will be right over us, but a little toward the warm side where lenticulars mostly occur.
In the meantime, spaghetti suggests a big trough in our area again about nine days from now. The later ACTUAL model outputs don’t show much of anything. What’s up with that? I’m hanging with spaghetti that later model runs will indicate a strong trough, and at LEAST another pulse of cooler air, and another minor chance of rain as we are going to see today and especially tomorrow as when become within the “ring of winds” aloft. Didn’t Johnny Cash sing something about that? Maybe it was Wall of Voodoo…
Below, some spaghetti for you showing a big trough over Arizona and the Great Basin which is not much reflected in the actual models, as noted. But, just watch my friend, how those model outputs will change to reflect a bigger trough about this time!
I thought you’d like to read this (Peru’s Niño), forwarded to me by Niño expert, Nate M. Pretty incredible to read about what is happening down there in the wake of the Big Niño of 2015-16, which really turned out to be more of a couch potato in terms of weather production in the Great SW.
But, all this winter, along the Equator near the coast of South America, there has been something we used to call an “El Niño”, but is downplayed or ignored these days because of a new definition that seemed to explain more weather when it occurred, “Region 3.4” a large zone along the Equator WAY out in the Pacific rather than something near the South American coast (that zone now called, “Regions 1 and 2”), as nicely illustrated by NOAA here.
But what has been the effect of what we might call the “Classic Niño”, a warm strip of water along the South American coast, one that doesn’t extend too far into the Pacific? “Read all about it”, as they used to say. Its pretty remarkable.
And here’s what the SST field looks like. Its boiling down there off South America! (Speaking figuratively, of course):
Peru’s Niño can be thought of as a “classic Niño”, the ones written about in the decades before about 1990 or so when the definition of what constituted a NIño (or Niña) was expanded and delineated more sharply among several definitions that were floating around. We ended up focusing on a region WAY out in the Pacific Ocean called, “Region 3.4” that SEEMED to explain more over the prior years.
What’s so interesting about this is that the “Classic Niño” has been underway pretty much all this winter, and we’ve had, especially in California, a classic Niño response; that is, abnormally heavy precip farther down the West Coast that no one anticipated.
Well, the correlations with Cal precip and “classic Niño” occurrences will take a huge jump upward after THIS winter!
End of Statement (hand-waving) on Niñoes.
Local weather statement: for immediate release
Cooler, fluctuating weather foretold here for that latter part of March, I don’t know how many weeks ago, is on the doorstep after the long, anomalously hot dry spell. Poor wildflowers have been suffering, too, fading, looking a little stunted after a great beginning, one rivaling the great displays of 2010.
All of the local weatherfolk are on top of this now, and so no point recasting that stuff. HECK, you can go to Weather Underground1 and get as “good as can be” forecast for Catalina (Sutherland Heights) out to ten days! And, there’s nothing worse for a weather forecaster with forecasting in his blood, than to be excited about an “incoming” and when you mention it to a neighbor he replies, “Yeah, I heard about that already. Supposed to get a quarter of an inch.” There is no air whatsoever in the “balloon” after that. So, if you have a weather-centric friend who says something about the upcoming weather, pretend that you haven’t heard about it yet, “DON’T say something as hurtful, as “Yeah, I heard about that already.”
So, here, we go the long route because most weatherfolk are afraid to go too far into the future because its often WRONG. Our models tend to lie a lot after about even a week, so only the brave go out even ten days!
However, here, we go out as much as two weeks and more because its not a truly professional site but rather want to get something out there earlier than other people, sometimes called a “scoop” in the news and weather business. That’s why our motto here is, “Right or wrong, you heard it here first!” Furthermore, if a longer range forecast posted here is WRONG, you won’t hear about it anymore!
Cloud maven person will say this about the first incoming of several fronts: comes in early Thursday morning, its strong! Rainfall potential: 10% chance of less than 0.12 inches, 10% chance of more than 0.75 inches. Best of those is the average, or about 0.4350 inches in this one. It has great POTENTIAL to be a soaker, but mods have been all over the place; hence, the large range of potential amounts. At least some measurable rain seems to be in the bag, a paper one please, because plastic is insidious. Note, CMP’s forecast is more generous than that found in WU’s latest forecast for Catalinaland.
The weather WAY ahead, unprofessionally so
Let us look beyond the professional forecasting limits to April:
We know we got several storms/fronts zipping across AZ as March goes out like a lion, but what about April?
Looks like that pattern will continue into April with temperatures below normal for the first part. The end of the unprofessional forecasting portion of this blog, though we do have our NOAA spaghetti to hang our umbrella on…. Check it out for about two weeks ahead.
Some clouds recent clouds, including a couple from yesterday
———————– 1Although “Weather Underground” might sound like an org has a radical origin, maybe something left over from the late 1960s, this particular one was NOT formed by 60s “weatherman” terrorists like Bill Ayers and Bernadine Dohrn (the link is for those of you who may have set trash cans on fire, as happened at San Jose State to protest the Vietnam War, to look back at those days in horror or nostalgia; take your pick) , but rather by genuine weather geeks (haha, I count myself among them, those that can’t get enough of weather, there can never be too much, like the guys mentioned in this “Cloud City” article.)
The chance of measurable between this afternoon and Saturday morning isn’t 10%, or even 50%, but 100% as seen from THIS keyboard. If you want a better forecast than that, go to the NWS, Tucson, or see Bob’s expert take. I like Bob. But we go for it here; don’t mess around. The last measurable rain, only 0.10 inches, fell WAY back on November 27th. I wonder if you remember it? Probably not. I don’t.
Rain hits after midnight tonight after a day of heavy middle cloud overcast (that would mostly be Altostratus opacus, probably with virga later, maybe some Altocumulus embedded or at the bottom or below that As layer, with mild temperatures. Don’t expect sunset color tonight since the cloud deck is likely to extend too far to the west for that.
These middle and upper clouds, whose bases will lower as the day goes on and during the night when the rain hits, are associated with a surge of moist air from the tropical Pacific. This chapter of rain will followed by an extremely sharp cold front passage (“FROPA” in weather speak) late Friday night or early Saturday morning with another round of light rain.
AZCat model output foresees quarter to half inch here in Catalina.
Wind will be a problem.
This situation will be accompanied by a really intense low developing to the north of us and the wind by tomorrow mid-day through early Saturday morning will be ferocious. We’re likely to see gusts here in Sutherland Heights to well over 50 mph from the SW as the wind bunches up against the Catalina Mountains, helping to increase speeds here in The Heights. CMP suggests putting loose stuff in the yard away somewhere. He might even do that himself instead of trying to find where all his baseball caps, left outside on the front porch, went the next day. Some composition shingles likely to come off, too.
The Weather WAY ahead
The good news here, if you like below normal temperatures and chances of rain or snow, is that the forecast models are indicating we’re in the mean trough position. Periodic fronts and troughs will affect the SW over the next two weeks, bringing with them at least a CHANCE of rain, while cooler than normal spells are virtually certain.
Check out the spaghetti:
Notice the broad dip to the south in those red lines beginning in the eastern Pacific Ocean then down to Baja and then back toward the east-northeast into the southern Plains States. The 5700 meter height contour (red lines) is pretty much on the edge of the jet stream, and a dip like this would be considered a weakness, a vulnerability for troughs in these plots. Remember these are initial starting conditions in last evening’s global data with DELIBERATE slight errors put into those data to see how slight errors affect the outcomes. There are almost no differences at the beginning, the errors are so slight.
And there are ALWAYS slight errors in our measurements, of course, so spaghetti helps pin down what those errors might do to embarrass us forecasters. When those red (or blue lines) cluster somewhere into a band, it means that the errors introduced have little effect on the position of the troughs at this level (500 mb).
For example, over there off SE Asia, the cold continent and the warm ocean constrain the jet stream into a tight bundle of contours. Errors don’t have too much influence on where that jet stream will be off Asia; its pretty much locked into place.
Down stream, things are more of a mess, but you can still see, in this case, where there is kind of a bunching to the south in the red lines in our SW domain. So, there would be, oh, moderate confidence of passing upper level troughs during these latter days of December. At least that’s what I see from this from here.
Worried about wildflowers now, due to the paucity of fall rains….so really hope December can come through with some major rains!
In case you don’t believe me, here’s the model crunch from our very own Banner University of Arizona Weather Department (aka, Hydromet and Atmos Sci Dept). You can watch the storm play out hour by hour here.
However, as you can see, to throw cold water on such a great prediction, we are in the HEART of a rather narrow band of heavy precip, which raises the uncertaintly level a lot on just how much rain will actually fall. Somewhere, these days, there is a Gaussian like distribution of the rainfall at point locations so you can see just what the model spread is in the rain predictions, but I haven’t located it and am too lazy to look right now. If I come up with that, will post it.
So, just as good as that, I will say that measurable rain will fall in Catalina between Sunday evening and mid-day Monday that the least likely amount is 0.15 inches (10% chance of less), which would be a real poop, and the most, 1.00 inches (10% chance of more, a luxuriant rain, washing so much dust off stuff).
The average of those extremes is usually is closer to the actual total, which in this case would be 0.625 (correction! 0.575! Egad, dividing by 2 is still pretty hard for me) inches at my house. The idea here is that we meteorologists often know what’s NOT going to happen better than what is, in the domain of precip forecasts, and so by starting with extrema, to be erudite there for a second, we can narrow our predictions down, not get too carried away as often happens here.
BTW, if you want really great, professional level forecasting besides that by the TUS NWS , see Bob’s discussions! He’s always got great stuff.
The first high clouds ought to be arriving later this afternoon. Have cameras ready. Should be a nice sunset to go with them since there shouldn’t be a total overcast to the west.
Note that within this swath, Catalina is predicted to get over an inch of rain! Note that the swath is not very wide. A wide swath of heavy rain would be one as wide as the State. So, we have to figure that this is a lucky hit at this time, and count on something less as a virtual certainty since the swath above will move around as new model runs look at it. Typically, they shift a little east over time in those future model runs. Hope not.
Have cameras ready for a pretty sunrise. Lots of high ice clouds up there.
The weather WAY ahead
Spaghetti suggests more rain chances after a several day dry spell following the Monday rains. Check out the “pretty strong” indications that we are in the trough bowl as the month comes to an end, meaning troughs should be populating Arizona during the last days of November. In turn, good November rains, and one seems to be in the high confidence pipeline for SE Arizona as a whole, means the spring wildflowers will be given a boost. I will go on record here as now forecasting, if that’s what this is, a wetter than normal November rain total1. Our November average since 1977 is 0.96 inches.
1This sentence will be deleted in the event of a drier than average November and will, therefore, not be on record.
Not much else to talk about, no rain of course; what is that?
But with so many colorful scenes yesterday, we can be partially sated by the lives we lead here sans rain here. October ended with a puny 0.01 inches in Sutherland Heights.
Now, because I grew up in California and remain a little Cal-centric, this brief diversion from AZ:
But droughty Cal got nailed though, from about San Luis Obispo, so we can be happy about that I guess. One station, Gasquet RS, near the Duck border, got just under 28 inches in October; stations in the Santa Cruz Mountains, way down by Monterrey, got between 14-17 inches! From the California-Nevada River Forecast Center, this nice map of October rainfall anomalies in that domain. Red is real dry, and that’s the color we would be in if it was the California-Nevada-Arizona River Forecast Center:
But let us not dwell any more of generous rains that others got, but celebrate the color and clouds of Arizona. Here are yesterday’s glorious scenes, beginning with a spectacular Altocumulus lenticularis under some Cirrus at dawn:
Now, just some nice lighting and color:
In a further celebration of dryness here, let us examine the rainfall cumulative rainfall predictions calculated by the University of Arizona’s Dept Hydro and Atmos Sci computer the period ending at Midnight on November 5th. Says the coming rain in the State misses us here in SE AZ while falling just about everywhere else, of course. Dang. Let’s hope it one of the worst model predictions ever!
Should be some good rain today in Catalina, FINALLY! Thinking maybe half an inch or so over the next 24 h, something decent, as tropical air drains o northward and over us out of tropical storm remnant, Roslyn (“Rozzi”).
Clouds and weather interruption:
Due to the name of our weather-affecting tropical storm, Roslyn, I am now reminded of a profound, life-altering “Hallmarky” chapter of life when I was in HS, involving another Roslyn (aka, “Rozzi”). In an another attempt to increase blog readers, those really not interested in clouds and weather anyway, I have inserted this story about a 15-year old, shy boy and his incapacitating crush on a Rozzi R as a junior in HS I suspect it is a fairly common one in some ways, although this one leads to the formation of other people with a different classmate. The Story of Rozzi R
This story was passed to Rozzi, who had no idea who I was, only in 2009, btw. She seemed to like it, and told me about her life, family and three kids. I think its OK to share it.
Back to weather, at 7:11 AM, one pulse of rain is within a half an hour or so. (Later, we only got sprinkles out of that first pulse).
Nice rainbow last evening; nice sunset, too:
The Prodigal Storm yesterday afternoon
Yesterday afternoon had quite the dump and something of a little ‘boob from the outflow winds, so much rain came down initially around Oro Valley/Marana, west Tucson, south of Pusch Ridge. Was heading this way, too, with nice big, black, solid-looking base. Started a video of it, thinking about the gush was to strike Sutherland Heights/Catalina.
Here it is, in all of its glory and subsequent dissipation:
Models, with spaghetti support, show a strong, but dry, cold front coming through next week, and fall will be in the air as nighttime lows drop into the 40s in our colder, lower spots, like at the bottom of Catalina State Park, in the CDO wash, etc.
0.02 inches of it, anyway, as the core of the jet stream at 18,000 feet or so passed by Catalina yesterday afternoon. Keep your eye on the orange and reddish streak in these progs from IPS MeteoStar yesterday morning beginning at 5 AM AST and how it slides over us as the clouds began to ice up:5 AM yesterday. Jet at this level races across central AZ.
11 AM yesterday. Maximum winds getting closer! Tiny Cumulus clouds begin to appear over the Catalinas and on the west to north horizon.
The jet separates deep cold air on the left side, looking downwind, and deep warm air on the south side. The deep warm air prevents Cumulus clouds from getting very deep due to inversions and stable layers where the temperature does not change much with increasing height, or even rises. The temperature at 500 millibars or 18,000 feet above sea level dropped from -17.7 °C to -21.1° C over TUS yesterday between 5 AM and 5 PM, while the temperature about which ice begins to form in our clouds dropped about 400 meters during that time. With the temperatures at the ground rising into the mid-70s as the colder air moved over us, Cumulus clouds deepened, reaching the ice-forming level between 1 and 2 PM.
Also with patterns like this, the cyclonic rotation (vorticity) in the air above us is increasing like mad, and that leads to a gentle upglide motion in the atmosphere, one that also helps cool the air aloft and usually produces sheets of clouds like Cirrus, Altostratus, Altocumulus and NImbostratus. But yesterday the air was too dry for sheet clouds to form.
First ice was noted just after 1 PM. Can you find it?
5 PM yesterday. Just passed! B y this time, Sutherland Heights had 0.02 inches as the tops of Cumulus and Stratocumulus complexes continued to cool and ascend. The sounding from TUS at 5 PM AST (launched about 3:30 PM AST) indicated the coldest tops had reached -20 °C or so, plenty cold enough for ice, virga, and light rain showers. Too bad the bases were so high since we could have had some real rain if they had been lower.
But, we were “lucky” to get that. Even the great U of AZ model had no rain anywhere near us late yesterday afternoon when it fell! THAT does not happen very often.
Nice Cu, ice, too.
Substantial rains, maybe half an inch or so, still on tap between May 6th-8th as previously foretold here. Yay! May averages 0.38 inches here in Catalina. More rain likely after that episode, too. So an above normal May in rain is pretty much in the bag now. Could be an especially great May, too.
In the meantime, step aside; a cold front is upon us, a dry one, unfortunately. Should arrive by noon, bringing some small Cu here and there, some Stratocu piling up against the Catalinas, and maybe some lingering Altocumulus lenticular clouds which we got right now (4 AM) downwind of the Catalinas.
Barometer will rise, too, as the cooler, denser air piles on top of it. There’ll likely be a brief windshift to the NW, followed by backing to the SW again.
Over the next couple of days, the deep cold air in the interior of a lingering, massive trough will settle over us, dry up top, but enough moisture in the lower layers below to produce eventually deeper Cumulus, though not today, ones likely to reach up to the “glaciation” level, which will be close to -12° C to -15° C in this situation beginning later tomorrow through the April 1st. The bases of the clouds will be near the freezing level.
Glaciation means that ice will form in those Cumulus clouds, and some (snow) virga will drop out the bottom. So, some snow showers or just light rain showers are likely on the Catalinas, maybe a trace or hundredth here, too, beginning later tomorrow through April 1st.
Should be some really pretty deep blue skies, too, cloud shadows producing quilt-like patterns on the mountains, that sort of thing we are so lucky to enjoy here.
As you know, this end of month March “lion” (at least in wind, anyway) was long foretold in the NOAA spaghetti. Remember how we could laugh at model outputs that didn’t have a big trough here at the end of the month?
But now we wait and see if we can drain a cloud or two of a hundredth. Overall rain chances not looking so “strong” now out of this whole several day situation. Dang.
Clouds will be around today, especially after the cold front goes by, but its unlikely they’ll have anything drop out the bottom.
“2warm4ice”, to be that bit textual.
Model says today’s cloud tops won’t reach -10° Ç, our magic temperature where we can usually start to thinking about ice forming in AZ clouds, those with our usual cool bottoms.
Of course, if you’re really sophisticated, you know that the temperature at which onsets in “continental” Cumulus clouds like we have here in old Arizony, is related to cloud base temperature:
The warmer the cloud bottom, the higher the onset temperature for ice1, “strangely believe it”, as we like to say here after Jimmy Hatlo the cartooonist thought of it first when he was making fun of RIpley’s “Believe It Or Not.”
Now onto the forecasting frontier, forecasting weather patterns way ahead, to far in advance and too specific to be truly professional
Let’s start with something easy. Its gonna warm up real good after this big trough goes by– see spaghetti below, where a big ridge moves over us for a couple of days. It won’t last.
Finally, at the extreme end of the medium range forecasting frontier, this:
Hence, the conclusion that we share that April, will in fact, have measurable rain. Of course, we only average about half an inch in April, as the overall climatology begins a serious a battle against rain heading into the ovenly days of May and June.
1The old English cloud scientist, Frank Ludlow (1952, Quart J. Roy. (haha, “Royal”, oh my) Meteor. Soc.) noticed this first, then that great Soviet Communist cloud scientist, A. M. Borovikov and his companions did (1961, Israeli Translations). Finally, Rangno and Hobbs woke up and noticed this tendency in 1988, (Atmos. Res.) and then again in 1995 (J. Appl. Meteor.–you’ll have to go quite a ways to find the relevant diagram) in their cloud studies and in comparisons with other ice onset reports.