How to Forecast Using Clouds- Part I

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posted on Jul, 31 2009 @ 11:45 PM
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Noticed a lot of people doing their own forecasting and analysing of weather patterns, so I thought I might share a bit of knowledge about how to forecast using clouds.

The most obvious place to start, is using cirrus clouds and contrails to foresee possible weather.

Cirrus clouds can be broken into four small categories. There is cirrus, cirrocumulus, cirrostartus and contrails. Each of these clouds consist of ice crystals, and they occur at heights greater than 20,000ft. It is possible for them to occur lower, but the environment is rarely cold enough in most parts of the world.

Cirrus clouds are characterised by a few different things. First off they can appear as thin wispy strands, hook shapes, or filaments (see below image for example). Secondly, they can also be seen in large twisted masses, and finally, they are also seen at the top of cumulonimbus clouds (thunderstorms), in the shape of an anvil. Contrails are also considered in the meteorological world, as cirrus clouds, providing they have persisted for half an hour. Cirrus we use in forecasting, is generally accompanied by cirrostratus, and is invading the sky from the west.



The second type of high cloud is cirrocumulus. Cirrocumulus clouds are characterised by small tufts or cells, occuring in sheets (called mackerel sky, when the sheet covers the entire sky as the resemble the scales of a fish). Unfortunantly cirrocumulus is not a very handy tool in forecasting, but it does make a spectacular picture

k43.pbase.com...


The third type of high level cloud, cirrostratus, is the high level cloud which is most useful for forecasting (fiorecasting using clouds that is). It is characterised by its thin, sheet like appearance. It may appear quite thick on some days, and on other it may be almost transparent, producing the halo and contrail shadow effects. The cirrostraus we use to forecast, will generally appear in a sheet, advancing from a westerly direction.

images.inmagine.com...

Since cirrus clouds are full of water, in its solid form, a large number of them is usually a good indicator that a cold front, with some wet weather is on the way. A contrail that persists prior to any cirrus clouds being observed is also a good indicator that the upper atmosphere is moistening rapidy. As contrails consist of ice, they also add moisture to the atmsophere, helping to fuel the cloud development.

en.wikipedia.org...

As a cold front approaches, rapidly moving cold air is thrust into areas of receding or slow moving warm air. High level clouds like cirrus and particularly cirrostratus form before any other clouds, as the warm moist air is thrust up, by the introduction of cold air, which in turn creates an unstable atmosphere. As the water vapour rises, it condenses into ice crystals, and saturates the air, causing cirriform clouds to appear and invade the sky. In some cases, cirrus and cirrostratus clouds will appear 2 days before the front is due to hit, depending on the speed it is travelling.



Occasionally cirrostratus and cirrus clouds will invade the sky as if a cold front was approaching, but the weather may not change. If that occurs, its a good idea to check your local synoptic chart to see if there is a cold front to the north or south of your location

Hopefully this helps a little bit for those people interested in doing their own forecasting, and I am happy to answer any questions (or challenges...i dont write things clearly sometimes) regarding this.

Happy weather watching




posted on Aug, 1 2009 @ 12:04 AM
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I just love the picture above with the reflection of the pond, wow, now that is divine, lol.

Please keep adding to this thread, it is so important with the lack of accurate reporting via the usual sources today. Is it just me or is the weather analysis getting worse now rather than better?

Also do you find any real indicators prior to Ice Storms that are reliable?

Thanks for this much needed thread.



posted on Aug, 1 2009 @ 12:20 AM
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Here are some clouds that passed me by but went on to rip up the town 9 miles east. I live in the Middle of Missiouri and if Oaklahoma is tornado alley, we are the bowling pins...




posted on Aug, 1 2009 @ 12:51 AM
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Originally posted by antar
I just love the picture above with the reflection of the pond, wow, now that is divine, lol.

Please keep adding to this thread, it is so important with the lack of accurate reporting via the usual sources today. Is it just me or is the weather analysis getting worse now rather than better?

Also do you find any real indicators prior to Ice Storms that are reliable?

Thanks for this much needed thread.


Thanks for the kind words antar


Will have to check up about the ice storms, we dont actually get them in Australia, so Im not sure if there are any precursors that indicate they may/will occur. Will get back to you on that.

Those cloud pictures are awesome. Obviously you must have just skimmed the edge of that supercell thunderstorm, and it was probably a good thing it did too!!



posted on Aug, 1 2009 @ 05:38 PM
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Hi Antar

I did a bit of digging for precursors that may indicate an ice storm. Unfortunantly there is nothing, cloud wise that would give us an early warning.

What you do need is a partially frozen precipitation (rain), falling as sleet. There also needs to be a thin layer of cold air, below freezing level near the surface. As the precipitation falls into warmer air below its point of origin, it starts to melt. Generally it becomes warmer towards the ground, but with freezing rain, the layer of cold air is trapped below (and above) the warm layer. As the rain passes through the warm layer and into the cold layer, it again becomes cooler, turning into supercooled water (which is water existing as liquid below freezing level). Then it falls onto an object, which has a temperature below freezing, it instantaneously freezes on contact with that object.

There are other ways to tell if freezing rain is likely, but I will go through them later, so hopefully this helps a little



posted on Aug, 1 2009 @ 07:08 PM
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Yes it does OZ, and I thank you for your time.

I do recall last years ice storm, here is how I remember it:

The news reports were coming in that we were going to have an ice event, they said it would most likely not be as drastic as 2006, but to be as prepared as possible to be on the safe side.

I had plenty on hand to have just stayed home but decided to go to town (16 miles) and pick up a few extra fresh things and what not. it was not so cold outside and so I only took a medium weight jacket with me.

The sky was grey and the air smelled like fresh clean water, or snow to me. The wind was minimal maybe 3-5 mph.

I stopped and dropped off a box of extras and water to an elderly disabled neighbor and across to another on my way to town to see if i could pick anything up for them, stayed maybe 3 minutes.

Off to town, I left my house at around 2pm, and was heading home hurriedly as the weather was changing fast and the cold front was on me as I left the store at about 3:00.

Heading home road crews were out spreading ice on the roads and it had begun to sleet as I drove. The sleet was hitting the windshield pretty hard and soon I was turning off my road it was now about 3:15 or so.

Driving down my road, I saw tree limbs and bushed covered in ice, the wires on the fences were getting coated fast too. I could hear limbs in the distant woods beginning to crack and pop.

It was at this point i had a huge adrenaline rush and made my way in to the house as fast as I could. The ground was already so slick I had a hard time getting up to the house.

That is how fast it happened. We were in a deep freeze without power as the ice broke the lines and damaged transformers out here in the country, but most of it went south at that point towards Arkansas to do the same type of destruction we experienced in 06.

It feels like little mini ice ages happening in the Midwest US OZ, where we once experienced snow fall and rain, seems like for the past two years every time we get any precipitation it turns into a dynamic ice event.

Could we be seeing the beginning of a mini ice age? How long before it begins to affect others world wide?

Does this have anything to do with the melting of the polar ice caps?

Oh one more thing, in both events we had an arctic cold coming down from Alaska mixing with the warm gulf stream winds from the south.



posted on Aug, 1 2009 @ 07:24 PM
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Being both a hang glider pilot and a boater, an awareness of weather has not only been a fascination of mine but also a necessity. Living in the tropics though, the rules tend to get skewed a little bit.

Approaching cold fronts are often, but not always, proceeded by cirrus clouds, our main indicator of an approaching front is that the northeast tradewinds will subside and the wind will begin coming from the southeast then move around to the southwest before the front arrives.

In the summer, we often see cirrus clouds coming from the southwest (moving opposite the tradewinds) but usually nothing seems to develop out of it other than sometimes an overcast that can last for a day or so.



posted on Aug, 1 2009 @ 08:51 PM
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reply to post by Phage
 


You are completely correct Phage. Its interesting to note that you get what appears to be frontal cirrus moving against the trade winds. Im assuming that would be related to a pressure system rather than a front. If you are located where I think you are, a low pressure system sitting out in the Atlantic would be a perfect reason for this to occur.

Almost got confused there with my high and low pressure systems....forgot you guiys up there in the north, spin in the opposite way to us






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