Thunderstorms, rain, hail, pummel Catalina finally!

We’ve waited a LONG time for a rain day.  It was so nice, so photogenic as well.   I hope you enjoyed it as much as I did.

Also, you may have seen the Froude Number1 in action as Cumulus congestus and Cumulonimbus clouds developed and went around the sides of the Catalina Mountains instead of developing over them and dumping big shafts of rain on them.  The heaviest rains yesterday were due to streamers of showers and with an OCNL TSTMS that were north and south of us, Oracleville, Bio2 area, and Marana, Avra Valley where over half an inch was logged in some places.

Still , we managed a third of an inch here in Sutherland Heights,  the first appreciable rain since I don’t know when, though,  I could look it up.    Too long, though, even for Catalina.

Some regional totals, 3 AM to 3 AM:
Precipitation Report for the following time periods ending at: 03:19:00  11/04/16
                    
              Data is preliminary and unedited.
              —- indicates missing data
                          
    Gauge     24         Name                        Location
    ID#      minutes    hour        hours      hours        hours
    —-     —-       —-        —-       —-         —-       —————–            ———————
Catalina Area
    1010            0.08      Golder Ranch       Horseshoe Bend Rd in Saddlebrooke
    1020            0.12      Oracle Ranger Stati          approximately 0.5 mi SW of Oracle
    1040            0.08      Dodge Tank                   Edwin Rd 1.3 mi E of Lago Del Oro Parkway
    1050            0.16      Cherry Spring                approximately 1.5 mi W of Charouleau Gap
    1060            0.16      Pig Spring                   approximately 1.1 mi NE of Charouleau Gap
    1070            0.24      Cargodera Canyon             NE corner of Catalina State Park
    1080           0.20      CDO @ Rancho Solano          Cañada Del Oro Wash NE of Saddlebrooke
    1100           0.16      CDO @ Golder Rd              Cañada Del Oro Wash at Golder Ranch Rd

Santa Catalina Mountains
    1030          0.04      Oracle Ridge                 Oracle Ridge, approximately 1.5 mi N of Rice Peak
    1090          0.16      Mt. Lemmon                   Mount Lemmon
    1110          0.16      CDO @ Coronado Camp          Cañada Del Oro Wash 0.3 mi S of Coronado Camp
    1130         0.28      Samaniego Peak               Samaniego Peak on Samaniego Ridge
    1140         0.08      Dan Saddle                   Dan Saddle on Oracle Ridge
    2150         0.16      White Tail                   Catalina Hwy 0.8 mi W of Palisade Ranger Station
    2280         0.04      Green Mountain               Green Mountain
    2290        0.16      Marshall Gulch               Sabino Creek 0.6 mi SSE of Marshall Gulch

Santa Catalina Foothills
    2090         0.04      TV @ Guest Ranch             Tanque Verde Wash at Tanque Verde Guest Ranch
    2100          0.16      DEQ Swan                     Swan Rd at Calle del Pantera
    2160        0.08      Sabino @ USFS Dam            Sabino Creek at USFS Dam
    2170        0.24      Ventana @ Sunrise            Ventana Canyon Wash at Sunrise Rd
    2190        0.16      Al-Marah                     near El Marah on Bear Canyon Rd
    2200        0.04      AC Wash @ TV Bridge   Agua Caliente Wash at Tanque Verde Rd
    2210        0.00      Catalina Boosters            Houghton Road 0.1 mi S of Catalina Highway
    2220        0.04      Agua Caliente Park           Agua Caliente Park
    2230        0.04      El Camino Rinconado          El Camino Rinconado 0.5 mi N of Reddington Rd
    2240        0.04      Molino Canyon                Mt Lemmon Highway near Mile Post 3
    2390       0.24      Finger Rock @ Skyli          Finger Rock Wash at Sunrise Rd

Yesterday’s Clouds

6:50 AM. "Shape of things to come."
6:50 AM. “Shape of things to come1.”  “Nothing could change the Cumulus shapes of things to come” yesterday, to paraphrase here, as evident in this Cumulus shedding ice in the downwind decaying end on the left.
DSC_9096
7:35 AM. Look at this little guy, so full of ice. Another harbinger of the ice-filled clouds about to arise, and with ice, precipitation, snow aloft, graupel (tiny soft snowballs), and even some hail (solid ice). You could guess here from how shallow this Cumulus cloud is that the bases must be at near the freezing level, and tops must be at least as cold as -10° to -15° C, cold for such a small cloud. But what would we call such a small cloud? Cumulus congestus praecipitatio or virgae (since the present of ice absolutely means some precip up there, not likely reaching the ground though. Shoot from the hip estimated depth 2 km, or around six thousand feet.
11:37 AM. Sure enough, as it got warmer, Cumulus congestus/small Cumulonimbus clouds arose trailing ice northwestward in huge plumes of ice. Note to airborne researchers: be sure to sample the older parts of the turrets that have trailed downwind and turned completely to ice even though that trailing portion doesn't look much like a Cumulus cloud. It you only sample the newly risen portions, you will cheat the cloud out of how much ice it can produce since it takes a little time for all the ice to form. Lotta early airborne researchers made this error, reporting too little ice, but, of course, if they were in the cloud seeding business, they wouldn't mind at all since they could report that clouds needed more ice, that from their seeding activities!
11:37 AM. Sure enough, as it got warmer, Cumulus congestus/small Cumulonimbus clouds arose trailing ice northwestward in huge plumes of ice. Note to airborne researchers: be sure to sample the older parts of the turrets that have trailed downwind and turned completely to ice even though that trailing portion doesn’t look much like a Cumulus cloud. It you only sample the newly risen portions, you will cheat the cloud out of how much ice it can produce since it takes a little time for all the ice to form. Lotta early airborne researchers made this error, reporting too little ice, but, of course, if they were in the cloud seeding business, they wouldn’t mind at all since they could report that clouds needed more ice, that from their seeding activities!
11:37 AM. Oh, so pretty, those dark blue skies punctuated by a little muffin Cumulus cloud. Aren't you glad you live here?
11:37 AM. Oh, so pretty, those dark blue skies punctuated by a little muffin Cumulus cloud. Aren’t you glad you live here?
1:25 PM. Showers and small Cumulonimbus clouds trail off the Catalinas north of Bio2.
1:25 PM. Showers and weak Cumulonimbus clouds trail off the Catalinas north of Bio2.
1:25 PM. Showers track westward south of Catalina while the clouds over the Catalinas dissipate or remain disorganized while heading toward us.
1:25 PM. In the meantime, stronger Cumulonimbus clouds and showers track westward south of Catalina  toward Avra Valley while the clouds over the Catalinas dissipate or remain disorganized while heading toward us.
2:33 PM. A voluptous Cumulus congestus in the process of transitioning to a Cumulonimbus calvus (ice is visible but top stil pretty firm and round looking), then Cumulonimbus capillatus (fibrous top)
2:33 PM. A voluptous Cumulus congestus in the process of transitioning to a Cumulonimbus calvus (ice is visible but top stil pretty firm and round looking), then Cumulonimbus capillatus (fibrous top)  AN older turret, looking all ice, leans to the left.  Precip was already dropping out the bottom of this fat cloud.  What kind would it be?  Grauple, without doubt since so much supercooled liquid water  would remain in this cloud amid the ice crystals forming inside.  Those ice crystals, nice and pristine when they first form, would have their pretty forms obliterated by droplets that would freeze instantly on them, making them little snowballs, falling faster and faster, collecting more droplets.
2:46 PM. Moving rapidly away from Catalina, of course, that cloud has now become a Cumulonimbus capillatus (hairy, fibrous top a,most completely composed of ice--some liquid)
2:46 PM. Moving rapidly away from Catalina, of course, that cloud has now become a Cumulonimbus capillatus (hairy, fibrous top a,most completely composed of ice–some liquid may still arrive at cloud top in new turrets before quickly converting to ice.)  A portion of a rainbow can be seen at almost ground level.
2:48 PM. In the meantime, pretty strong storms, now having thunder, rage S through W of Catalina.
2:48 PM. In the meantime, pretty strong storms, now having thunder, rage S through W of Catalina.
3:14 PM. While we didn't have any great clouds near us, at least we had some nice lighting (not LTG) on the mountains from time to time.
3:14 PM. While we didn’t have any great clouds near us, at least we had some nice lighting (not LTG) on the mountains from time to time.
3:41 PM. Finally, the dramatic skies were shifting northward and measurable rain was on the doorstep. Looking SW toward Pusch Ridge and the Tucson Mountains.
3:41 PM. Finally, the dramatic skies were shifting northward and measurable rain was on the doorstep. Looking SW toward Pusch Ridge and the Tucson Mountains.
4:43 PM. Took awhile, but a decent Cumulus with a nice base now transitioning into a Cumulonimbus plopped some big drops and hail down. Streak at right is a hail particle with its fall distance in about 1/400 of a second.
4:43 PM. Took awhile, but a decent Cumulus with a nice base now transitioning into a Cumulonimbus plopped some big drops and hail down. Streak at right is a hail particle with its fall distance in about 1/400 of a second.
DSC_9220
4:47 PM. The hail got a little bigger and I took a picture of one of the stones, a little smaller than pea-sized in case you don’t believe me that some hail fell, too. Sometimes I think people don’t believe what I write, especially in footnotes….
5:02 PM. While the sunset was dramatic, it didn't bring the color hoped for, but this line of dark clouds presaged another bit of rain for Catalina.
5:02 PM. While the sunset was dramatic, it didn’t bring the color hoped for, but this line of dark clouds presaged another bit of rain for Catalina.

Except for a morning or afternoon sprinkle, no rain in sight, just a warm up back to above average temperatures.  Dang.

The End

———————-

1The young fluid dynamicist,  Richard Penniman, fascinated by the flow around mountains, and who later became known as the rock and R&B entertainer,  “Little Richard”,  first brought the Froude Number to public attention in his song, “Tutti Froude-e.”  The title, after an early release failed to capture the public’s imagination,  was later revised for greater “accessibility”,  to the song we know today as, “Tutti Frutti.

2Who can forget “Max and the Storm Troopers” and that great song?  I would submit, “everyone.”  Of course, few know that after 1968 they changed their name to “Led Zeppelin.”  And that, my friends, is  “the rest of the story”,  as Paul Harvey might say if he was lying about something anyway.

Rain 2 for November 2013: 0.23 inches, lightning and a couple of grape-sized hail stones

We have a monthly rain total that’s not zero! But will there be more this month?  Stay tuned until November 30th!  (Nothing imminent.) In the meantime, a very pretty blue sky day today pocked with residual Cumulus clouds, maybe some virga. There’ll be nice cloud shadows and sun on the Catalinas again today.

In the meantime, here are the Pima Country reports for last evening’s rain.  The heaviest amount seems to be at our end of the Catalinas at Pig Spring, with 0.39 inches.  Nice.

Yesterday’s clouds and why

Not exactly the way they were supposed to go, the ice cloud shield WAS on the horizon to the NW at mid-day but didn’t advance over us, but rather fizzled out.  That’s OK.  What was left of it enhanced a spectacular sunset through the rain.

The Cumulus clouds were the stars of yesterday, doing something in the way that the old rock band, Jethro Tull used to do.  The members of JT would come out on stage as roadies, fiddle around with equipment for awhile, then suddenly turn around and began playing!  Oh, who can forget Jethro Tull and that Aqualung album that roiled the rock waters back in 1971 by interrupting heavy, driving rock with acoustic interludes and flute playing (!!! )? What were they thinking?

Well, our Cumulus clouds pulled a fast one, too,  after hanging around, fiddling around not doing much, then blammo, here comes the ice around 4:30 PM, followed by an eruption into an honest-to-goodness Cumulonimbus cloud with a strong rain shaft, sending forks of lightning to the ground, and pea to grape-sized hail bouncing off the roof with winds gusting to over 30 mph. This spectacular happenstance was triggered by a surge of much cooler air in conjunction with the lifting of air associated with our approaching trough just above those Cumulus tops yesterday afternoon.  That steepened the lapse rate;  spring-loading those Cumulus clouds as it were, allowing tops to rise and still be that bit warmer than the surrounding air and stay buoyant as they rose. Here are a couple of TUS balloon soundings rendered by the Cowboys of the U of WY:ann 2013110412.72274.skewt

ann 2013110500.72274.skewt

While cloud fattening and ice was expected late in the day with sprinkles and light showers, the U of AZ mod run based on 5 AM AST data was spectacular yesterday morning in foretelling this larger eruption as that cold air moved over us.   But were grape-sized hail stones and LIGHTNING expected?  Not only “no”, but “HELL no”.

Here’s your day, reprised below, of which the MOST IMPORTANT part was the first detection of ice, very tough yesterday, but a precursor to the rain that began to fall a few minutes later.  You can also reprise your day here thanks to the U of A time lapse films.  Watch what happens around 5 PM, if you can read the tiny font in the lower left hand corner.

Here is the pictorial of your cloud day below:

12:06 PM.  Flatness.
12:06 PM. Flatness.
3:49 PM.  Clouds fattening, no ice visible anywhere yet.  Nice cloud street generated upwind of Pusch Ridge, floating over Catalina.  Shows wind direction at cloud level is from that direction.
3:49 PM. Clouds fattening, no ice visible anywhere yet. Nice cloud street generated upwind of Pusch Ridge, floating over Catalina. Shows wind direction at cloud level is from that direction.
4:01 PM.  Nice cloud shadows and sun moving along the Cat Mountains, too.
4:01 PM. Nice cloud shadows and sun highlights moving along the Cat Mountains, too.
4:34 PM.  Something's definitely happening now.  Note turret protruding on the left.  Clouds evolving into larger masses to the south, the cloud street having broken up.  And, these are clouds that
4:34 PM. Something’s definitely happening now. Note turret protruding on the left. Clouds evolving into larger masses to the south, the cloud street having broken up. And, those massing clouds are upwind of us.  Still, no ice evident.
4:35 PM.  Ice! I can't believe it.  Its going to rain!  Can you find it?  This is REALLY tough.
4:35 PM. Ice! I can’t believe it. Its going to rain! Can you find it? This is REALLY tough.
4:37 PM.

4:37 PM. Close up of ice. A higher top was breaking off to the NE and was converting to ice.

 

5:07 PM.  By this time, ice had formed in cloud clusters all around Catalina, and this beauty erupted upwind.
5:07 PM. By this time, ice had formed in cloud clusters all around Catalina, and this beauty erupted upwind.
5:22 PM.  About to strike with hail, lightning, wind and rain.
5:22 PM. About to strike with hail, lightning, wind and rain.
5:35 PM.  While the rain and hail weren't done yet, it gave this sunset pictorial.
5:35 PM. While the rain and hail weren’t done yet, it gave this colorful scene reminiscent of summer sunset color except that the sun would be setting WAY over there on the right out of view.
5:40 PM.  Second thunderstorm with hail in formation upwind of Catalina.
5:40 PM. Second thunderstorm with hail in formation upwind of Catalina.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The End.

0.52 inches here, 1 to 1.5 inches on the CDO upper watershed; will it run?

May take Jake Horse out to see if the Sutherland Wash is running, anyway, if the CDO is not running here in Catalina.

Thunderstorms (at least 4 separate ones yesterday), with hail, graupel, wind, rain;  what a nice day for Catalinans and our environs.  Lightning was still visible as of 7:52 PM last evening, and close enough that  thunder could be heard, technically meaning a thunderstorm is in progress in weather parlance.  Here’s some pea-sized hail for you, sent by a listener, “Dave”, in Sutherland Heights:cropped IMG_20130308_104705_630

Was awakened by a moderate rainshower just before 3 AM.  Dropped 0.03 inches in a few minutes, to bring the total to 0.40.  Another shower followed within half an hour, but bucket didn’t tip for even 0.01 inch.  May have to jiggle it to get that extra 0.01 inch that I KNOW fell. Hahahah.

In the meantime, exulting over the large amounts, so well foretold by the U of AZ Beowulf Cluster run from 24 h ago.  Truly amazing!  Our total here was also well=predicted by that model; amounts in this storm increase northward reaching 0.87 inches at Oracle State Park, 0.55 inches at the NE corner of Saddlebrooke.  We SO needed a good rain.  Here’s where the totals are:

201303091030_pptreport

Here are some mind-boggling statewide totals from the USGS, some approaching two and a half inches of water content at Sunflower near Payson!  How great is that?!  Really, this has been a billion dollar storm in dropped water and snow. Maybe it should have a name now.

2013030911_AZ pcp USgS Sheet1

You will can also access rainfall data from the U of AZ rainlog.org network here, and from CoCoRahs national network for Arizona here.  As always, its necessary to point out that in the rainlog network, the measurements reported this morning will be assigned to yesterday’s date, while the ones in the CoCoRahs system will be assigned to today, March 9th.

Since its unlikely to rain for at least 10 days, I thought I would overdo the precipitation data for our billion dollar storm.

Sadly, as you will see in this Pima County ALERT gauge totals above,  we in the north end of the County really got the nice rain; most of the county did not.  We were lucky we were that bit farther north because it wasn’t the wind direction helping us out in most of the storm; that “help” is taking place now because the wind is more from the west at cloud levels.   Going into yesterday yesterday evening the wind at cloud/mountain top levels was from the south-southwest rather than from the west, and normally that more southerly flow helps the south facing sides of the Catalinas, as much as us.  So, it was more to do with cloud top temperatures and those clouds being a bit too warm to the south, while northward and to the northwest (perpendicular to our jet stream), the temperatures decreased rapidly at the same level in the atmosphere, and that in turn, allowed cloud tops to deepen more as they went nortward.  Make any sense?  Here’s a map of temperatures aloft for yesterday, two graphics to try to explain this:

A 500 millibar map at 5 PM AST.  Center of coldest air is to the northwest of us at that time, gets colder over you as you take Highway 79 to Florence and beyond.  Cloud tops do, too.
A 500 millibar map at 5 PM AST. Center of coldest air is to the northwest of us at that time, gets colder over you as you take Highway 79 to Florence and beyond. Cloud tops do, too.  The full loop is here.

 

Mapm for the same time with colors showing temperatures getting colder to the NW of us.  More likely to have deeper clouds and thunderstorms as you go NW.
Mapm for the same time with colors showing temperatures getting colder to the NW of us. More likely to have deeper clouds and thunderstorms as you go NW.  Full loop is here.

First, here’s last evening’s TUS sounding, as rendered by the Cowboys of Wyoming.  Its got some writing on it:

The Tucson sounding at 5 PM AST, yesterday, March 8th.
The Tucson sounding at 5 PM AST, yesterday, March 8th.  Cloud tops marked by asterisks to represent ice crystals, and bottom by little “o’s”.  The arrows in roughly an “R” shape is an attempt at replicating the thunderstorm sign used by NOAA.  Even though the clouds were topping out at less than 25,000 feet, they still contained enough ingredients such as hail and updrafts to generate enough static electricity for lightning.

———begin tedious stream of consciousness again, probably worth skipping——–

Graupeling hard here at 3:38 AM!  Third shower since getting up!  Pounding roof.  Very small, like rice grains.   Just quit, like someone turned a light off at 3:41 AM.   Tells me its a new cell that just formed with narrow strands of precip/graupel.   Investigating…no echo at 3:36 AM nearby… waiting for next 6 min sweep…    2:42 AM:  No echo!  I have not seen this happen before.  Could it have developed and died in less than 5 min?  Did not tip bucket!  Its just like yesterday, we had no less than four hail/graupel episodes and I was beside myself thinking of those balls of ice bouncing OUT of my rain gauge collector!  I was being short-changed in the amount of precip I could report.   I think I am going to have to add to my rain total, maybe 0.03 inches due hail balls that bounced out

——————–end of tedious stream———————-

OK, now up to 0.13 inches in rain that has fallen since about 3 AM.  This is great, because now the total amount in the storm is 0.50 inches here!

Yesterday’s clouds

After a few sprinkles-its-not-drizzle amid brief sunbreaks yesterday morning, the first thunderstorm rumbled across Marana and the Oro Valley at 9:30 AM.

9:55 AM.  Thunderstorm with hail and heavy rain moves into Oro Valley.
9:55 AM. Thunderstorm with hail and heavy rain moves into Oro Valley.
10:21 AM.  Looking upwind toward Pusch Ridge at the bases of  a line of rapidly moving Cumulus congestus clouds.
10:21 AM. Looking upwind toward Pusch Ridge at the bases of a line of rapidly moving Cumulus congestus clouds.
10:25 AM.  Hail-producing cloud has passed by, but shaft increases in size and visibility.  This is a time when tremendous amounts of ice is forming in the cloud, ultimately leading to its demise as a fluffy area looking area of only ice crystals.  Without the liquid droplets, that disappear during this stage where ice forms explosively, no graupel or hail can form. Its a normal life cycle event for cells like this.
10:25 AM. Hail-producing cloud has passed by, but shaft increases in size and visibility. This is a time when tremendous amounts of ice is forming in the cloud, ultimately leading to its demise as a fluffy area looking area of only ice crystals. Without the liquid droplets, that disappear during this stage where ice forms explosively, no graupel or hail can form.
Its a normal life cycle event for cells like this.
12:12 PM.  Another line of young Cumulonimbus clouds races toward Catalina and Sutherland Heights, a recurring theme yesterday.
12:12 PM. Another line of young Cumulonimbus clouds races toward Catalina and Sutherland Heights, a recurring theme yesterday.
12:23 PM.  Passage of that complex of Cumulonimbus clouds shown in the prior shot resulted in this hail shaft trail on the foothills of Samaniego Ridge.  Hail shafts are very narrow.  If it had been snow, there would have been much greater coverage.
12:23 PM. Passage of that complex of Cumulonimbus clouds shown in the prior shot resulted in this hail shaft trail on the foothills of Samaniego Ridge. Hail shafts are very narrow. If it had been snow, there would have been much greater coverage.
2:30 PM.  But the day wasn't done then, was it?  Here something in the way of an arcus cloud rolled across Oro Valley and onto the Catalinas.  Thought maybe a tube might form.
2:30 PM. But the day wasn’t done then, was it? Here something in the way of an arcus cloud rolled across Oro Valley and onto the Catalinas. Thought maybe a tube might form.
4:55 PM.  Just kept on giving.  Here yet another line of developing Cumulus congestus, just reaching the precip stage a little upwind of Catalina, dropped a few more graupel particles while going on to dump heavily farther north.
4:55 PM. Just kept on giving. Here yet another line of developing Cumulus congestus, just reaching the precip stage a little upwind of Catalina, dropped a few more graupel particles while going on to dump heavily farther north.  This recurring pattern of clouds developing,  able to become deeper with colder cloud tops is the primary reason the north part of Pima County did so well yesterday and this morning,

Today’s clouds

These early morning stratiform (flat) clouds will disperse into Cumulus and Stratocumulus in clumps. They’ll be cold enough at cloud tops for ice and virga, but clouds likely will be too shallow for more than a hundredth or two in the heaviest precip areas around Catalina. Things dry out later in the day, the Cu becoming smaller, so the best chance of measurable rain is before, say, 2 PM.

Get camera out fast, too. THere was a huge dump of hail or snow on Charoleau Gap last night or this morning I suspect, and it looks spectacular even now at 6:53 AM. Its local, because its not seen at the same elevations to the south on Samaniego Ridge. But, it will just be gorgeous with those deep blue skies and white Cumulus clouds all around.

The End, finally, I think.

All’s well that ends well

What a nice day yesterday was, ending with this fabulous, but run-of-the mill sunsets we get to see here in the Catalina area on a regular basis.  Yesterday was interesting because we had two graupel (soft hail) showers, the first about noon, and the second with a blast of thunder (1) at 1605 PM.   If you weren’t lucky enough to get any, measure it and report it to the National Bureau of Standards, or the NWS, here’s what it looked like on our old chaise lounge a  couple of minutes after it fell (see below).  Some of it was “conical graupel”, pointed on one side, though that is not visible here.  Graupel, soft hail form when there aren’t many ice crystals in the cloud and the cloud is chock full of droplets at below freezing temperatures.  Those droplets freeze instantly onto the ice crystal as it makes it way down to the ground, eventually losing all of its identity as it become a little snowball.  Usually, where this happens in the cloud is in a very limited region, and, it usually doesn’t last for a long time.  So, consider yourself especially “lucky” to see graupel/soft hail, hail.  I do.  If you want to relive yesterday’s clouds, as seen from the U of A, go here.   “Above Catalina” is at the left, beyond Pusch Ridge.

What’s exciting now is that something akin to an atmospheric iceberg is barreling down on us (SE AZ) from the north.  This “cold low” center, representing a column of extraordinarily cold air in this case, goes from the ground all the way up through the “troposphere.”  IN this case, the troposphere is squashed down to less than 20,000 feet over Wy0ming right now. The stratosphere is above that, and above “cold lows”,  the stratosphere dips down over them.  Usually its twice that height at our latitude.

Here’s what I am talking about, shown in this morning’s 500 millibar pressure map (about 18,000 feet above the ground) or usually half way up through the troposphere (map courtesy San Francisco State U.)  The winds flow along the green lines, ones that bend gently toward the west over the Great Basin.  That bend in the wind represents an area where a small low center amid this giant river of wind will form in the next 24 h and that little center of circulation should pass right over us!

Now, not a single model output that I saw from last night’s runs had enough moisture in this forming upper center to have snow even fall on Mt. Sara Lemmon (e.g., the U of AZ regional model from last night).

A few days ago, the Canadian model was suggesting a signficant storm here from this center. I really believe it.   Well, that’s “bye-bye” since the center is not well to the west of us as that Enviro Can model indicated it would be, but rather will end up right over us (which means much drier).    The U of WA model run from this morning’s data says that a little “L” will be right over my house on Thursday morning (see reddish map below) !  Man, it will be cold over me!    Might lose some plants in this one before its over.

However, I am going to stick my neck out and expect (hope) there will be just enough moisture for flurries around here (Catalina area) anyway tomorrow into tomorrow evening.

BTW, the U of A has just issued a special weather discussion here.  You’ll want to check this out!