Too bad Steven Sondheim wasn’t a meteorologist. He might have written some great weather songs. Instead, he chose to write about “clowns.”
Hmmmm. Perhaps he WAS thinking about some weatherman in those days when he used the word “clowns.” Who can forget that the LA Times headline about weather forecasting in 1981; the headline that declared that weather forecasting in the media consisted of, “Clowns and Computers.” Personally, I think humor has no role whatsoever when talking about weather…. Oh, well, I digress.
Today will be really exciting for us weather buffs (buffoons?) We WILL be excited as mom Nature gives us a reprieve from the steady diet of glorious days, sunrises, and sunsets (this morning’s at left), paradise really, with a blast of wind and then cold, likely to inflect more damage on our probably dead palms here in Tucson-Catalina-Saddlebroke. Also this will be punctuated by a really exciting cold front passage, one where the temperature is likely to drop at least 10 degrees Fahrenheit within minutes as the wind shifts to the W then NW after those bruising S-SW winds. Probably here on the knob, we’ll see 40 mph or more in momentary gusts. Good-bye dead palm fronds.
When will the rain/front hit?
Well, lets say you don’t have a supercomptuer, a Cray, a Fujitsu, or access to thousands of PCs for parallel computing purposes to solve all the euqations in your 57-layer nested grid model using GFS-WRF outer boundary conditions, etc., for your subdomain. What the HECK would you do, besides peruse the internet for answers, which can take a LOT of time? Besides, we know that the internet is loaded with bad information…
Here’s what I do in this “bind.” You get out a little piece of paper or Hollerith card (2nd photo), and you use the technique of “extrapolation.” You got to the internet and check out the recent movement of the cloud band feature upwind of you by marking where the leading edge was, say, 4-6 hrs ago, then where it is currently, and move the two marks forward so that the back one (the old edge) is at the front of the feature and look at where that 4-6 hrs of past movement puts it 4-6 hrs from its present position. Presently, the middle of this mass of Altostratus clouds (last photo) we have over us, will be around Noon to 1 PM using that technique. However, there is no precip in that fat band of clouds, though one would think they would be thickening up as they approach us due to the Cat Mountains and overall effect of the Mogollon Rim. So, maybe there will be some sprinkles around. Our best models suggest the main rain band and front will not arrive until well after dark., and “extrapolating”, using the past 13 h, suggests the front won’t hit until dawn tomorrow! So, it”ll be a long time comin’, but “a change gonna come, yes it is.”
In the meantime, the biggest conundrum in today’s forecast is is what are these Altostratus layer clouds going to do (last photo), the ones at presently zooming above us in winds of nearly 100 mph, bases at 20-22, 000 feet? There are no radar echoes in Arizona to the west of us here in Catalina, yet as you can see they are drooping precipitation down at us in the form of virga. As the air moistens below these clouds, as it should given the approaching system, that virga will tend to hang down lower and lower. I would guess with this scenario that some very light rain or sprinkles will start reaching the ground this afternoon into this evening in Catalina ahead of the main rain area, the one due in well after dark. Our best model for this area is, of course, at the U of A, right here, and you can see the precip creep in then. I think I would use them (U of A and NWS since the last time I used the “extrapolation” technique described above was in 1989 I think. However, you’d be surprised, when timing fronts coming in off the Pacific (where I was forecasting then), how well this simple, simple technique worked.)
Don’t be surprised if a bit of a clearing comes up toward later this afternoon to sunset. Its not unusual to have a vast amount of quasi-threatenbing cloud go overhead all day, maybe with a few sprinkles, and then have a thin slot or brief clearing before the heavy clouds and rain move in later in the evening. That appears to be suggested in the satellite imagery today. We shall see! What an interesting two days ahead!
Still looks like a little snow in Catalina Sunday morning. U of A mod indicates that the total amount of precip will be around half an inch.
BTW, while you’re digesting all of the above, here is where the weather records that were set for yesterday are. You can see that a LOT of records were set yesterday! Generally low temperatures and record snowfalls for the day in the northern half of the US beginning in the Mid-West and “thence” westward to the Pacific Coast.
OK, enough rambling!