0.33 inches so far; more rain on way! Dense blog contains annotated photo!

Looks like CMP is low AGAIN on his prediction!  Thought a third was the most that could fall  in our present storm chapter (10% chance of more, that is), and best estimate, 0.165 inches.  Now it looks like met friend and professor at a major university will be much closer with his half an inch prediction.  Very painful.  Kind of like Stanford with their brainy team beating the Washington Huskies  in fubball .    It really hurts.

Let us begin today with a look at desert grasses from this summer and falls rains.  Pretty deep, knee high in some areas, but as we know here, full of nettles.  Kind of a cool look though.

7:53 AM.
7:53 AM.

Was heading out to see, what from Google Space, appeared to be a new meteor crater near me, one maybe the astro boys missed.  Turned out it was just a house under construction, pretty much underground as well.  Kind of a cool thought to build like this, lots of energy saved, which is always good.  Cell phone service likely compromised.

8:11 AM.  An earth house under construction.
8:11 AM. An example of an earth house under construction here in the Catalina area.

Yesterday’s clouds

…and a dense discussion of detecting ice in them.  I am hoping that my followers noted the time of the first appearance of ice in those Cumulus and Stratocumulus clouds  that began to fill in during the middle and late afternoon.  As that happened, a few raindrops sputtered down here just after 3 PM as that happened.  You should have logged both these events, the first visual appearance of ice, and when those drops fell in your weather diaries.

The whole point of this blog is the detection of ice in clouds by layman and laywomen, or “laypersons” I guess it should be now days.  This is because if you see ice developing in lower clouds, something will be falling out of them soon.  Ice grows in water clouds at below freezing temperatures at the expense of droplets.  Therefore, if they stay in a water cloud long enough, they will get heavy enough to fall out.   Poor droppies disappear, unless the air is really rising fast.

An interesting side note is that the air FLOWS THROUGH  clouds, exiting on the downwind side.  A cloud does not just float along as is.  It is moving slower than the air, even itty bitty Cumulus clouds the cloudy air is being replaced constantly.  The cloud is really moving upwind relative to the air! The POSITION of the cloud moves downwind, but SLOWER than the air that goes into it.

However, if ice crystals form in a small cloud then, they will fall out as single crystals at the downwind edge; they are not going to reach the ground unless you’re on a mountain top.  You saw a fair amount of ice exiting the downwind end of clouds yesterday, falling out and evaporating in the dry air there.   Where the cloud is wide, then they can gain some mass, collide with droplets, or other crystals and fall to the ground.

2:38 PM.  No ice nowhere.
2:38 PM. No ice nowhere.  Windy conditions not shown.
DSC_1420
2:38 PM. Cumulus and Stratocumulus clustering to the south-southwest of Catalina, but no sign of ice.

You need clusters of crystals locked together, called “aggregates”  or ones that have gone through riming, collisions of ice crystals with drops at below freezing temperatures that freeze on the ice crystal making it more massive to get rain drops to the ground.   Riming is what leads to graupel (soft hail) and hard hail (the latter to crystals impacting larger, often precipitation-sized drops that freeze on them).

For air travelers, or those who examine tree icing after storms, rime ice is white and produced by small cloud drops; clear icing is caused by much larger drops, usually drizzle or rain drop sizes.  If the drops are too small (much less than about 20 microns) they are too small to hit anything and rather go around solid objects.  Let’s say you’re on the top of Ms Mt Lemmon, say at 8.000 feet in the fog.  The temperature is 24° F.  Its windy.  You look around and you see no icing on the pine trees  trees up.

Where are you?

Ans: at cloud base.

That’s because itty-bitty drops, too small to hit on pine tree needles are flowing around the needles.  Some great comments to make that would enhance your stature as a cloud maven junior is to offer your companion the information, “Wow, look at those trees!  Here we are ing the freezing fog, and yet they have no ice sticking to them!  That means the cloud droplets are pretty small, smaller than about 20 microns! I guess we’re at the base of this cloud system above us.”

These would be really great things for you to say.  Of course, as you drove up to Mt. Lemmon, you would know already how far above cloud base you are, but, what the HECK.

You’re at Ms. Mt. Lemmon again,  You like it up there when its in the fog.  This time the temperature is 25 ° F.  Its windy.  The pine trees are loaded with rime icing, the ice juts out in the direction from which the wind is coming.

Where are you?

Answer:  At LEAST a few hundred feet, more likely a thousand feet or more above cloud base.  Drops have reached sizes above 20 microns in size, as they usually do at these heights above cloud base in old Azy.  Later, you notice that the clouds are topping Sam (Samaniego) Ridge at the 6500 foot level.  Now, they can’t be disconnected layer clouds, but rather SOLID from base to where you are.  Drops are tiny again at the bottom of each layer.

Here’s another example.  You get up in the morning after a cold winter storm to see “iced trees” on Ms Lemmon.  Another comment you could be making is that, “Wow (always begin with “wow”), those clouds must have really been low based last night, way down on Sam Ridge!”

Riming on trees is analogous to the collection of fog droplets by trees and vegetation along the west coasts of the continents in onshore moving banks of Stratus and Stratocumulus clouds that intercept hillsides.   These can be significant sources of water.  Some studies of droplet collections by trees have found that under the tree, something like 20-40 inches of “rain” can be collected by a tree in northern California.

Wow, I can’t believe all the information I am providing today!  Its really incredible.

OK, to first visible ice yesterday, 3 PM:and

3:00 PM.  FIrst ice begins to eject out the end of that Stratocumulus complex upwind of Catalina.  When the body of the cloud began to be overhead, a few drops reached the ground!
3:00 PM. FIrst ice begins to eject out the end of that Stratocumulus complex upwind of Catalina. When the body of the cloud began to be overhead, a few drops reached the ground!
3:00 PM.  Close up of ice ejecting out the downwind end of this Stratocumulus complex.
3:00 PM. Close up of ice ejecting out the downwind end of this Stratocumulus complex (that hazy stuff).
3:30 PM.  Classic example illustrating the air flow through a cloud that's producing a little ice.  What kind of ice?  Looks like colder crystal types, plates, stellars, maybe some dendrites.
3:30 PM. Classic example illustrating the air flow through a cloud that’s producing a little ice. What kind of ice? Looks like colder crystal types, plates, stellars, maybe some dendrites; defintely not warm crystal types like needles and hollow columns that form at temperatures above -10° C.
DSC_1477
4:49 PM. Nice lighting.
DSC_1481
5:21 PM. Wind shift clouds, those lowest ones on the horizon, begin to appear to the north-northwest horizon, toward Casa Grande.
DSC_1482
5:31 PM. The sun going down amid Cumulus or could be called, Stratocumulus castellanus.
DSC_1485
5:32 PM. OCNL LTG DSNT NNW at this time.   Again you see those wind shift, frontal passage type clouds here.  A wind shift to the NW didn’t hit here until about 1:30 am when the rains and temperature drop hit.

 

 

The End

Tropical fetches

Flash: Very light rain (R–) falling at 5:30 AM!  Amazing…  Won’t measure though, as thickest clouds are already sliding away.  But still, great to see, to smell the scent of rain in the desert, and feel the drops in this little surprise sprinkle!

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Forgetting about that last big bust, namely the last big trough of the season that let us down by producing no measurable rain, let us now consider tropical finches, or rather, FETCHES, since an example is coming soon, one that might well bring rain.  (I know what you’re thinking; you’ve heard that before, wrongly, I might add as in the LBT-LBB).   Hope springs eternal I guess, though rain is predicted by both the USA and Canadian models, so there is some mathematical backing to this hope.  See below, as rendered by IPS MeteoStar:

Green pixelation approaches Tucson-Catalina urban complex.
Green pixelation approaches Tucson-Catalina urban complex on Friday, May 29th at 5 PM,

 

Valid for 5 PM AST May 29th.
Valid for 5 PM AST May 29th.

Yesterday’s clouds

You can see them all at once from the great U of AZ Weather Department time lapse video for yesterday here in case still shots with captions aren’t enough action for you.

5:59 AM.  Virga falls from Altocumulus opacus.  This can also be seen as like a little slice of the tops of many rainy days when cloud tops aren't below about -30 C or so. As here, those tops are usually still comprised of mostly liquid droplet clouds in which ice crystals form, grow, and fallout.  If the air is not rising to replenish the doplet clouds, then you will be left with a patch of ice and virga, a patch that will eventually die.
5:59 AM. Virga falls from Altocumulus opacus. This can also be seen as like a little slice of the tops of many rainy days when cloud tops aren’t below about -30 C or so. As here, those tops are usually still comprised of mostly liquid droplet clouds in which ice crystals form, grow, and fallout. If the air is not rising to replenish the doplet clouds, then you will be left with a patch of ice and virga, a patch that will eventually die.  Estimated top temperatures, -12 to -15 C, a little colder than shown on the TUS sounding for yesterday near this time because we are farther into the cold air aloft than TUS is.  Also, it would be unlikely that clouds like these would produce ice at the indicated TUS balloon sounding top of Altocumulus at -11 C.   With their geerally small droplets, it needs to be colder than that.  Egad!   This is way too much info!  But what kind of ice crystals would you expect in a water-saturated enviroment at around -13 to -15 C?  Yes, that’s right, pretty Christmas tree stellar crystals, maybe some aggregates of dendrites.  Remember, too, for aggregattes to form that concentrations of the crystals must be more than about 1 per liter.  Too, since they are falling through a droplet cloud with droplets  larger than 10 microns in diameter, you would expect those stellar crystals and aggregates of dendrites to exhibit some riming, that is, have impacted some of the cloud drops as they grew and fell through the cloud, though keeping in mind that the crystals must attain a diameter of about 200-300 microns in diameter before riming commences, helped by the fact that stellar crystals (planar ones) fall face down like a clown does when he’s trying to make people laugh and trips over something.  Also, I think someone in that big house on the right is about to have a baby.
9:40 AM.  With all the cool air over us, it wasn't long before Cumulonimbus clouds began boiling upward, giving someone some rain.
9:40 AM. With all the cool air over us, it wasn’t long before Cumulonimbus clouds began boiling upward, giving someone some rain.
9:53 AM.  While Cu boiled up quickly on the Catalina Moutains, and iced-out a plenty, they never really got the depth required to produce much more than sprinkles and virga.  Can you spot the little bit of ice on the right side of this Cumulus mediocris?
9:53 AM. While Cu boiled up quickly on the Catalina Moutains, and iced-out a plenty, they never really got the depth required to produce much more than sprinkles and virga. Can you spot the little bit of ice on the right side of this Cumulus mediocris?
10:30 AM.  Nice example of the tremendous amount of ice being produced by such modest clouds (see right side here--nothin' but ice).
10:30 AM. Nice example of the tremendous amount of ice being produced by such modest clouds (see right side here–nothin’ but ice).
1:01 PM.  By early afternoon it was all over, the clouds too shallow, the tops too warm to produce ice even though they were still well below freezing.  Just the way it is.  Guess warmer than -10 C (14 F) at cloud top when you see a sky like this with no ice.
1:01 PM. By early afternoon it was all over, the clouds too shallow, the tops too warm to produce ice even though they were still well below freezing. Just the way it is. Guess warmer than -10 C (14 F) at cloud top when you see a sky like this with no ice.
6:47 PM.  Sunset so-so as high clouds to the NW blocked the sun so it didn't under light these clouds.  Here, Cu flatten as the heat of the day, such as it was at 85 F,  cold for late May, dies away,
6:47 PM. Sunset so-so as high clouds to the NW blocked the sun so it didn’t under light these clouds. Here, Cu flatten as the heat of the day, such as it was at 85 F, cold for late May, dies away,

The End.

Weather “stagecoach” full of storm presents set to arrive on Friday

Don’t really need me anymore.  Everyone’s on top of this ” incoming” now, set to begin in the area overnight on Thursday, the one you’ve  been reading about here since maybe last October I think.  So, feeling sad today, also because it looks like its going to be a bit too warm for snow, which I think I mentioned about a dozen times. Maybe I will take it out on you by boring you with a science story, one about ice in clouds…but one featuring such stalwarts as Sir Basil Mason, Stan Mossop, John Hallett, Pete Hobbs, Alexei Korolev, and others.  Interested now?

But first, a few nice cloud shots from yesterday so you don’t get too mad at me for boring you first:

2:07 PM.  CIrrostratus fibratus (has detail, not just an amorphous veil).
2:07 PM. CIrrostratus fibratus (has detail, not just an amorphous veil).
4:21 PM.  Cirrus spissatus patches and dog, Zuma (named after the acclaimed dramatic series, Baywatch, which took place at Zuma Beach, also where the author, whilst not storm chasing spent a LOT of time.
4:21 PM. Two dense patches of Cirrus spissatus patches and dog, Zuma (named after the acclaimed dramatic series, Baywatch, which took place at Zuma Beach;  also where the author, whilst not storm chasing,  spent a LOT of time.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5:22 PM.  Cross section of a Cirrus uncinus (hooked at the top).  This shows how the ice crystals forming at the top first get heavy enough to fall out, but if encountering drier air, start to evaporate, slow in fallspeed, and as in this case, form a flat layer of tiny crystals at the bottom of the head of Cirrus uncinus.  Likely a little moist again at that bottom location so the tiny guys don't away very fast.
5:22 PM. Cross section of a Cirrus uncinus (hooked at the top). This shows how the ice crystals forming at the top first get heavy enough to fall out, but if encountering drier air, start to evaporate, slow in fallspeed, and as in this case, form a flat layer of tiny crystals at the bottom of the head of Cirrus uncinus. Likely a little moist again at that bottom location so the tiny guys don’t away very fast.
5:29 PM.  Sunset in Cirrus (spissatus and others).
5:29 PM. Sunset in Cirrus (spissatus and others).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Cloud ice science story

(drink some coffee, maybe take an extra swig of an “energy drink” if venturing forward)

Kind of takes the fun out of it when other people are saying what you want to say by yourself, lilke today’s forecast for Friday’s storm.  Kind of like being second when you publish “new” results behind other researchers who “got in” a little a head of you (like Korolev et al.-with Hallett!) did in 2004 reporting the FIRST image of a shattered frozen drop they said.

Drop shattering during freezing; what about it?

It was thought not to happen in natural clouds after that embarrassing episode back in the 1960s when the Great Knighted, Sir B. J. Mason1 and his student, Swinbank (1960), reported drops exploded with they froze.  Liquid centers tried to get out of the ice shell as the drop froze from outside in, as you would expect, but then blew up when the freezing water expanded inside the shell.  Looked pretty good.

There was only one thing wrong, their findings weren’t valid for real clouds.

They put too much CO2 in their cloud chamber (that’s right, the very SAME stuff that’s supposed to make the earth warmer and warmer year after year but has been sitting around lately, about 15 years actually, not doing anything) and that CO2 in the experiments turned out to make the outer ice shell real weak, and also the CO2 came out of solution in the water in the liquid center to make matters worse by expressing gas through the shell.  I wonder how many people have done that?

This was found out by researchers in my very own group before I got there, Jim Dye and Peter Hobbs, a few years later.  When real air was used, the drops didn’t explode.  So, down that hypothesis went that exploding drops caused a lot of ice to form in natural clouds.

End of story?  Nope.

Later, Hobbs with grad student, Abdul Alkezweeny, repeated the experiments with freezing drops, but this time instead them just sitting there, had them rotate as they froze and they DID shatter some, but not a lot!  This was back in 1968.

But no one was reporting images of shattered drops.

In those days,  there was a HUGE amount of unexplained ice in clouds.  Cloud chambers on the ground and in aircraft, found that little ice formed until the air IN THE CHAMBER was at least as cold as -20 C (-4 F), but instrumented aircraft repeatedly found tremendous amounts of ice in clouds that had never been colder than -10 C (14 F).  Hence, an enigma.

But the explanation that a few drops exploded, sending out thousands of ice shards never gained any ground because there was never any observational evidence that it happened.  Instead, an Australian researcher, originally from South Africa, Stanly C. Mossop, with John Hallett, discovered in 1974 that a bar moving through a cloud chamber between -2.5 C and -8 C, caused ice splinters to eject from SOME of the little drops hitting the bar and freezing on it.  But the drops had to be at least 24 microns in diameter, fairly large for cloud droplets, or nothing happened.  Also, if they moved the bar too fast or too slow, nothing happened.  So, there were a lot of criteria involved in this process, temperature range, drop sizes, speed.

So, the Hallett-Mossop riming-splintering hypothesis was born.  They assumed the bar, moving at the fall speeds of soft hail, showed what soft hail did inside clouds:  multiply ice content!

It was an exciting time to see that the mystery of all that ice in clouds at higher temperatures was finally explained, not needing, shattered drops or anything else.

But there were some problems.  In the early days, it was thought that this process, to raise the ice concentrations in clouds much, would take as long as 1-2 hours because it was a “cascade” process.  The few first splinters had to grow to sizes there they fell fast enough to bump into drops and cause ice splinters to eject.  Well, that wasn’t right.  Natural clouds formed ice MUCH faster than that, as you here in Arizona know so well.

The experiments continued and it was found that shattering helped this process (assuming it occured, but even more important was the freezing of drizzle and raindrops.  When those froze, they became instant rimers, splintering objects, and so the time for a cloud, but one having drizzle and raindrops in it, and in the right temperature zone, just between -2.5 and -8 C, was cut down to minutes, something like 10-20, to get ice concentrations from about 1 per cubic meter, to tens of thousands per cubic meter, a real rain cloud.

Except for a single image of a drop half by a researcher using a cloud camera with a glider in the 1970s, no one had reported a shattered drop.  Then along come Korolev et al. (with the great Hallett!) in 2004 reporting shattered drop images in a Canadian frontal band using an advanced cloud camera.  They wrote that it was the FIRST images ever reported of shattered drops.  Rangno and Hobbs (2005) also reported images of shattered drops in clouds around the Marshall Islands, thinking at the time that they were going to be first in line, and then discovered the Korolev et al. report.  It was a sad day to find that reference, as a researcher that was thinking about the glorious days ahead, the keynote addresses to important conferences, that would result from being first in line with something and then other people would always have to reference you.

As Ecclesiastes wrote, their is hardly anything new under the sun if you’re slow going about it.

Published another paper on shattered drops back in ’08.  But, found they didn’t SEEM to be making a big contribution to the ice content in clouds, less than 10%.  You can go here to see that I didn’t make that part up. That was kind of sad finding, too.  You want what you find to be HUGE, and it wasn’t so huge as I hoped.

So, riming and splintering remains our best, most accepted explanation for the great amounts of ice in clouds that aren’t so cold, though the author and Hobbs, have mostly found it wasn’t powerful enough to account for the speed of ice development.  Only the author’s friends, Stith et al (2004),  have reported a lot of ice that couldn’t be explained by the riming-splintering mechanism as have  R&H over the years.

But it would be so great if others confirmed the Stith et al findings.

The End for now.

 

———————-

1Wiki doesn’t do a very good job, and doesn’t even list his outstanding updated, Physics of Clouds text published in 1972, the “bible” of cloud physics in those days!  Unbelievable.

2Riming: Think of what happens to an airframe in a liquid drop cloud at below freezing temperatures.  HELL, here’s a photo by the author from the author-occupied Lear Jet 35 flying in supercooled clouds over Saudi Arabia, 2006,  The weapon-looking things under the wings image precipitation particles like raindrops and snowflakes using laser beams with light sensitive diodes at the other end, one that when shadowed, give you a two dimensional image of what went through the laser beam.

ann DSCN1223 rime icing
8:01 AM, December 16, 2006.

 

11:02 AM, December 10th, 2006.  Had to land at Hail, a small, pretty town north of Riyad to pick up some supplies, ones for the randomized cloud seeding experiment underway.  It was interesting that we could carry these boxes labeled "Explosive" to the Lear Jet without any notice.   Hmmmm.
11:02 AM, December 10th, 2006. Had to land at Hail, a small, pretty town north of Riyadh to pick up some supplies, ones for the randomized cloud seeding experiment underway. It was interesting that we could carry these boxes labeled “Explosive” to the Lear Jet without any notice. Hmmmm.  They were there because that’s where another NCAR radar was besides the one at Riyadh, and a plane might have to land to continue seeding if it ran out of the seeding flares like the ones inside these boxes.

 

 

Clouds without comment

Remember Consumer Reports, “Quotes Without Comment” page?  Well, I am lying like anything here1.

Only ONE comment today (I’m lying again), but its about wind today.  It will pick up suddenly from the north later this morning or in the early afternoon, and be gusty and cold.  We here in Catalina get more of this north wind than, say, TUS, which is blocked from this wind by the Catalina Mountains.  A big high is bulging into Utah, a state north of us, that’s why.

Next rain chances, a weak one late Wednesday or Thursday, and a stronger one around the 20-22nd, the latter as spaghetti has been suggesting for some time now.

Your cloud day below in case you were inside watching football television all day:

7:03 AM.
7:03 AM.  Note light rainshowers on north horizon.  Only a trace here.
9:14 AM.  Looks pretty much the same.  Hmmm.  That's a comment.  When it comes to clouds, I guess I just can't shut up, even when they're boring.
9:14 AM. Looks pretty much the same. Hmmm. That’s a comment. When it comes to clouds, I guess I just can’t shut up, even when they’re boring Stratocumulus.
9:15 AM.  Only a minute later!  Yes, a "concerto in gray" yesterday, and I want to make sure you see all of it.
9:15 AM. Only a minute later! Yes, a “Concerto in Gray” yesterday, to allude to some music that has not yet been written (perhaps it will be one day by a depressed composer), and I want to make sure you see all of the gray we had. Gray was my favorite color in elementary school! THought you’d like to know that. Man, after a second cup of coffee I am just exploding with interesting information!
11:49.  Still "Overcast in Stratocumulus"; could be the second movement in "Concerto in Gray."  Signs of break up here. another potential
11:49. Still “Overcast in Stratocumulus”; could be the second movement in “Concerto in Gray.” Signs of break up here.
11:50 AM.  Some of you are dropping away like this horse.  Can't take it anymore.  Well, I demand a million dollars to stop blogging!
11:50 AM. Some of you are dropping away like Jake the horse. Can’t take it anymore. Well, I demand a million dollars to stop blogging!  Note, however, that “Dreamer” the horse is still paying attention, setting a good example.
3:26 PM.  Skies eventually opened up and our pretty deep blue skies returned amid the small Cumulus and shallow Stratocumulus,  a rousing, happy finale to our  "Concerto in Gray."
3:26 PM. Skies eventually opened up and our pretty deep blue skies returned amid the small Cumulus and shallow Stratocumulus, a rousing, happy finale to our “Concerto in Gray.”
3:58 PM.  "Frosty the Lemmon"; could be a popular Christmas song.  If you stepped away from football television for even a minute, you might have noticed this interesting look on Ms. Lemmon.  This frosty look is almost certainly due to "riming" on the trees, the collection of supercooled cloud drops in clouds that are not snowing much or at all.  Substantial water can be collected by trees on mountains when supercooled clouds envelope them.  Hope that science not wasn't piling on the boring for you.  Piling on can be a penalty in football if it happens late like in this blog.  I demand two millions dollars to stop blogging!
3:58 PM. “Frosty the Lemmon”; could be a popular Christmas song. If you stepped away from football television for even a minute, you might have noticed this interesting look on Ms. Lemmon. This frosty look is almost certainly due to “riming” on the trees, the collection of supercooled cloud drops by the trees in windy clouds that are not snowing much or at all envelope them. The liquid drops hit and freeze and buildup on them, much like airframe icing.  Substantial water can be collected by trees on mountains when supercooled clouds envelope them in windy conditions like yesterday. Hope that bit of science wasn’t piling on the boring for you. “Piling on” can be a penalty in football if it happens late,  like in this blog.  I demand TWO millions dollars to stop blogging!
5:20 PM.  OK, some ice cream on your plain oatmeal; a pertty sunset, pastel Altocumulus above (gray, of course) Stratocumulus.
5:20 PM. OK, some ice cream on your plain oatmeal; a pertty sunset, pastel Altocumulus above (gray, of course) Stratocumulus.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The End, at last.  You can wake up now, horsey!

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1It comes pretty easily to weather forecasters, but you do have to speak with conviction; a certain degree of authenticity has to be imparted when lying.  :}