First of all, how did it get to be 2016 so fast?
Yep, a dramatic Christmas Eve storm, complete with rain and bluster, maybe even ending with a little snow, in case you’ve been in a cave for the past couple of days and haven’t heard about it. Media folks have been all over this, so am tuning it here just a bit, if, in fact, I can, for Catalina.
The wind today in Sutherland Heights will likely gust to over 40 mph from the southwest in 1-2 second bursts here , similar to the wind in the last big couple of FROPAs, so best to put loose stuff away.
In fact, the U of AZ mod from last evening sees winds of 115 mph above TUS at mid-day at just the 500 millibar level (15,000 feet or so above Catalina), a quite unusual strength of wind at that elevation, to give an idea of how strong the jet stream will be above us today. So, if it looks like the clouds are moving too fast, as in a time lapse movie, they are!
The core of that jet at 500 millibars passes over during the middle of the day, and that pretty much should coincide with the onset of rain as it usually does. So, look for rain to start around between 11 AM and 2 PM AST today based on that passage; the U of AZ mod output from last evening’s global data sees the start time somewhat later, between 3-4 PM. Be ready, though; it will come in a hurry! From IPS MeteoStar, this for 11 AM AST today, a real screamer of a jet is overhead:
We’ll have the usual “temperature slam” when the wind shifts to the NW here in Catalina during the FROPA late this afternoon or early evening. Looks like it will be a good 15° F drop, typically occurring within an hour, the first ten degrees in 15 min or so, with the temperature likely ending up in the mid-upper 30s. This is where some snow is possible. Imagine, a little SNOW in parts of Catalina on Christmas Eve is possible.
And with fronts/jets as strong as this, the rain band with the front should lead to at least moderate rain for a couple of hours. “Moderate rain”, probably “immoderate” in intensity for some desert dwellers and snowbirds, is 0.10 to 0.30 inches per hour. So rain will pile up pretty good during those periods of “moderate rain. ” Even a couple of hours of that intensity will lead to a substantial amount for our desert.
AZ mod (see link above) sees half inch to an inch here in the Catalina area to Mt Lemmon! That would give us a December total that’s above average, something we haven’t seen in a few months, an above average monthly total. A shot from hip from this keyboard yesterday to a friend was for a lesser total, 0.40 inches in Sutherland Heights1. Truly hope it is LOW!
One of the best sights today will be the transition in the clouds from dawn today (if any) until the jet core gets here in the middle of the day. Typically, on the right hand side of the jet (looking downwind), which is also the warmer side of it, the air is stable and its a great environment for lenticular clouds (smooth ones that hold in place, such as downwind of Ms. Mt. Lemmon).
As the jet core arrives at mid-day, which divides that warmer air from much colder air aloft on the left side, looking downwind, the lower clouds deepen up or move in, merge with higher cloud layers, ice forms begins to form like mad, and you start to see virga and precip all around. So, a pretty dramatic sky change should occur in the middle of the day today; have camera battery charged up, and maybe video or time lapse cameras ready to go as well.
Some cloud shots from yesterday’s “in between” day:
The exciting possible weather WAY ahead
We have a penchant here for pointing out quasi-disastrous storms that appear in the models beyond the normal skill period of 7 days or so. Remember last year, when Cloud Maven Person was talking up those gigantic, Big Niño storms that would appear in the models, but not one actually occurred as shown? Typically, as we all do, we look at the NOAA spaghetti factory outputs to see if there is much credibility to those sometimes wild predictions. As in the current weather, the indications of frequent trough passages was well indicated in those crazy plots more than 10 days ago. (How much precip will come with them is very “iffy” but we’re doing well this time!)
Well, there’s another set of “doozies” showing up in the mods now, ones that roar out of the central Pacific and into California, just like we expected with last year’s Big Niño! How odd. Those kinds of trajectories over the warmer waters of the eastern Pacific lead to the heaviest of all rainfalls in California, and heavy amounts here in AZ. Here’s my talking point, this:
But does “spaghetti” support these exciting model outputs? I don’t know because I haven’t looked yet. But let’s do look at a couple and see if catastrophic, well, heavy anyway, rains are headed to Cal, and maybe AZ, too. The onset of this “break through” pattern begins in about nine days or so (exact timing will vary a bit):
Moving ahead into the distant forecast future….(wow, this is getting to be too long again!):
Will look at this in a few days, noting that the ACTUAL model outputs will bounce around this “solution” but SHOULD tend to gravitate back toward it if it does bounce away from it (producing what would be considered an outlier).
Fun times in weather following ahead!
1Feel I have to ride that 0.40 inches rain prediction out since its “out there” and it was in the context of a friendly competition with a friend whose also big faculty member at a famous university in Fort Collins, CO, as well as a Catalina snowbird. In this regard, I have noted that some friends change their forecast with each model run, then in retrospect, select the forecast they made that was closest to the observed amount of the many they made, and then claim that they “really nailed” a rain prediction for Catalina.
Yesterday’s blog was re-written and re-organized some after finding several occasions of not such great writing and org.