ARL Model Graphics

ARL Model Graphics
Air Resources Laboratory
Posted 4/2010 / Updated 12/2023

https://www.ready.noaa.gov/READYcmet.php

This site is recommended by John Scott as a source for Skew-T graphs [John's notes]
There are numerous tutorials on how to read a skew-t charts, but rather than maintaining links, simply google
- how to read skew-t charts
The site also offers other graphic model products and John uses it as a "one stop shop"
On disadvantage is it is a little cumbersome because you need to enter an anti-automation access code for each new view
- You can partially back up with your "browser back button" to select different times without needing to reenter the access code, but you will need to re-enter a new code to change locations.
The big advantage is that you can view multiple graphic products from multiple forecast models for any location you enter, and you can look pretty far into the future, compared to the VGB balloon which looks at the past. You can get skew-t charts quicker from other sources like Windy.com, but the NOAA charts have some advantages like better resolution.

The see a Skew-T graph
Note: reviewing Skew-T sounding graphs for different locations can be cumbersome and time consuming but they are often one of the best tools to visualize the atmospheric profile.

Reference the [Blank Graph for Unit Conversion] from Celsius to Fahrenheit and Millibars to Feet MSL
From the SCPA Weather Menu, open the model page in a new Browser Tab
- It is time consuming to configure, so once you tunnel in, you don't want to loose your place. To view multiple models for comparison, see [strategy] below.

Enter a location then "Continue" some local coordinates below / see location in [Google Earth KMZ] or [JPG]
Coordinate note, the NOAA page uses decimal degrees, which is different than your IGC files which log decimal minutes

Spanish Ranch	35.06	-119.95	Plowshare LZ below Takeoff by Hwy 166
New Cuyama	34.94	-119.69	Mid-Cuyama Valley near the airport
SB Canyon	34.83	-119.55	Santa Barbara Canyon
Twitchell Reservoir	35.00	-120.34	Just inland from Santa Maria
Sedgwick Reserve	34.68	-120.04	Half way between Santa Ynez and Figueroa Mountain
Santa Barbara	34.45	-119.7	Near the Botanic Garden in Mission Canyon or you can simply enter SBA for the Airport. The airport has different surface weather than the mountains, but the soundings look at weather above the surface. I don't think a few miles will make much difference, but I haven't studied the inner workings of the models.
Ojai	34.47	-119.2	Near Senior Canyon (below Stooges and Twin Peaks)
Fillmore	34.44	-118.93	Near the main LZs out in front of Oat Launch
Pendola	34.52	-119.57	Up the Aqua Caliente Creek Canyon (Forest Rte 5N15) just north of the Pendola Ranger Station and Middle Santa Ynez Campground
Three Sisters	34.6	-119.46	On the Divide Ridge north of Monte Arido
Pine South Side	34.6	-119.3	The rocky ledges above Hwy 33 below the south launch
Pine North Side	34.7	-119.32	The large ranch fields north of Pine Mountain and the Lockwood Vly Rd
Lockwood	34.76	-119.05	Mid Valley Airport
West Antelope	34.8	-118.7	center valley half way between Quail Lake and the first group of round fields
Mid Antelope	34.83	-118.4	middle group of round fields north of the Fairmont Butte over the Skyotee Ranch Airport
Edwards AFB	34.9	-117.9	SW end of the runway just west of the larger east lake
Tehachapi	35.1	-118.4	fields 3 mi SE of the airport
California City N	35.2	-118.0	North of California City / South of the Cantil (Honda) test track
Garlock	35.4	-117.78	Just south of "town" on the flats
Ridgecrest	35.6	-117.7	Just south of town
Simi Valley	34.27	-118.76	Mid Town
Altadena	34.18	-118.1	Base of Foothill Point NE of Pasadena
Crestline	34.19	-117.32	CSS / Andy Jackson Airpark at the base of Marshall

Select a model under the drop down list for "Soundings"
- Under Sounding (John Scotts says the NAM is more aggressive with the lapse rate and the GFS is good at predicting high clouds)
  - NAM Model (12km, 84 hr, 3hrly, CONUS, Pressure)
    - I mostly use the NAM above. 3 hour intervals is plenty for our use and 84 hours lets me look out about 3 days
  - GFS Model (1 degree, 0-192, 3hrly, Global, pressure)
    - I'll use the GFS if I need to look out further. 192 hours equates to about 8 days
- Click on GO next to the selected sounding model
- Accept the default Forecast cycle (it is the most current, but you can look back if you are doing a post mortem) click NEXT
Configure the Parameters
- select the Profile Graphic Size, Recommend the largest size, 120 DPI (the default is 96 DPI)
- enter the access code (but don't click on Get Sounding just yet)
- Select a date and time form the Time to plot drop down list
  - 18-UTC ~ 10 am PST, 21-UTC ~ 1 pm PST (or 11 am and 2 pm PDT)
    - will also look at 15-UTC and 00-UTC (8 am and 5 pm) if I have the time and want to see the progression. We don't launch at 8 am, but are often in the air at 5 PM on good days.

Click on "Get Profile" (and Strategy for viewing multiple graphs)
- You can click your browser back button to change the date and time, but you can't jump to a different model or location without starting over.
- If you want to toggle between different models, forecast times, or locations, use multiple browser windows, or better yet, save the images... see next
- You can save the GIF image files which will let you record several forecast times for a particular model without having to re-enter coordinates and access codes. If you are going to save the images for comparison, then it's better to use just one window and back up with your browser back button so when you right click on an image and select "save image as", it will default to your last directory tree location and you won't need to tunnel in from your default "save-to" location.
  - I recommend using a file naming scheme that will sort and group, then when you save an image you can click on the last image saved name and simple edit the time in the file name.
  - The file naming scheme I use is "model" "sounding date and time" "for" "location" "day" "time". I use UTC time as designated by z but use 24Z for 00Z in the afternoon. Example file name: nam_2017_11-29_12z_for_ojai_29_21z, which translates to the NAM model run on November 29th, 2017 at 12Z (4 am PST) for Ojai on the same day (the 29th) at 21Z (1 pm). Then the if I want to save the next time, I simply copy the file name and change the 21Z to 24Z. To group and sort, I keep our local days together, so the NAM time in the image will progress from 29_21Z to 30_00Z, but I'll use 29_24Z. If I'm at the end of the month, then I'll add days to the month, for example, 29, 30, 31, 32. After saving all the images I'll sometimes put the different locations in different sub-folders, then when I open with a viewer, I can have multiple viewer windows open, one for each location, and toggle through in the location's time sequence without getting too confused about which location I'm looking at.

To read a Skew-T chart, there are tutorials available at:

[John's notes]
or simply google how to read skew-t charts

Information on Blip Maps can be found at: http://drjack.info
recommended reading by Don Taber