Looking for the tops

[ChristianGodin]

Hello,

Anyone could tell me if there is a ways to get the tops of the cloud for a specific area in the State?

In Canada, you go to nav canada, at the following adress, clik on: "Graphic FA", and you get a good idea of the tops and the freezing level.

Is there anything comparable for the US at some website?

http://www.plandevol.navcanada.ca/cgi-bin/CreePage.pl?Langue=anglais&NoSession=NS_Inconnu&Page=forecast-observation&TypeDoc=html

[bnicolette]

Christian, about the best thing that I have found for forecasting the tops (other than pireps) is the ADDS flight path tool. You can download it here:

http://www.aviationweather.gov/adds/fptapplication/

You can enter your station list. Then select relative humidity under the weather tab. On the right side of the map you can select the altitude. I have found it to be fairly accurate but would NEVER depend on it solely for trying to make a flight when it's cold expecting it to reliably forecast clouds and tops. However, when in use with pireps it is a great reference tool.

[FlyDave]

You can get the forecast tops from the FA (Area Forecast). I've made the FA part of my personal weather breifing every time I plan a flight.

[Piloto]

Is kind of impractical to use web info for cloud tops since by the time you get there the tops have either gone up or disappeared. At least that has been my experience in Florida where build ups rise pretty quick. I found a more accurate assessment by using the XM\WX Echo Tops feature. It allows to me decide whether to climb or deviate. Satellite imagery (contrast) over the Bahamas also gives you an idea of the cloud tops. The whiter the clouds the higher they are.

José

[bnicolette]

Definitely true for the south Jose. However, in the north during the winter months the cloud tops are generally low, stable and thin. Hardly any vertical development at all. But I couldn't agree more that using the web is not by itself a good method especially when trying to avoid icing conditions. Which is why I assume the OP is asking the question?

[ToddDPT]

Don't forget about Skew-T diagrams. They should show you tops and bases. This is still experimental though but it is nice to look at these along your flight path.

[moodychief]

Skew-t charts will show you the layers also. How can you say they are experimental when the information is from the soundings of the weather balloons the weather service launches every 12 hours. That is the only problem with skew-t...they aren't real-time.

[ToddDPT]

There is no doubt a wealth of info with skew-t. I shouldn't have used the word experimental but rather underutilized. It is my understanding that not many pilots are using them or even know what they are or how they work.

www.pilotworkshop.com have a great weather series that sheds light on them.

[Jeff_S]

Ditto on the skew-T logs, but since no one else posted a link to get to them, here it is:

http://rucsoundings.noaa.gov/

If you're not familiar with how to use this web page and read the charts, there's a link to a tutorial at the bottom of the page. These are part of my regular flight planning any time I think there will be IMC-type weather.

[jlunseth]

You can get the ground temp. and elevation at a particular location, then go to the infrared (visible) chart. There is a color scale for temperature on the chart. The chart is showing you temp. of the highest clouds (or the ground if no clouds). So determine the temp of the highest clouds from the temp scale (its in degrees C), subtract the ground temp in C, and divide the difference by 2 (the lapse rate is generally 2 degrees for each thousand feet). Then if you want MSL, add in the field elevation. The infrared chart can be found at aviationweather.gov, under Satellite>United States on the left side. Click the infrared button at the top to get the infrared chart, it defaults to just plain visible clouds.

Skew T is also very good. It charts temp. in red and dewpoint in blue at a specific point. Wherever the two lines meet and stay together for awhile (temp.=dewpoint) there will be condensation (clouds). The infrared method I mentioned earlier can be "fooled" by a strong inversion but the skew T "actual" soundings are not. You will see inversions on the skew T. The red temp line will be moving to the left (falling with altitude) then it suddenly reverses course and goes hard right. That is a rise in temp., and I have seen inversions above a cloud deck of as much as 10 dC. The skew T "actual" is from actual weather balloon soundings at a specific location at a specific time. There are also skew T models that essentially model what the skew T would be expected to look like at a point between soundings, or a time in the future.

[gsengle]

There is tremendous value to using the ADDS flight path tool beyond just tops. I would add it to planning for any instrument flight... relative humidity for various altitudes, wind planning, freezing levels, etc. Makes it all very easy to visualize.

Greg

[kortopates]

Another weather products that actually forecast clouds by layers (e.g., 6-12K, 12-18K, above 18K etc) is at http://weather.rap.ucar.edu/model/ That and Adds flight path looking at relative humidty are the better pre-flight planning tools. Of course, Satellite pictures with temps are only good for current tops