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MOS F.A.Q.

Check here for general questions about MOS. Individual product pages contain more detailed information for a specific MOS product. If you still cannot find an answer, please feel free to contact us

Do you archive the MOS guidance?

Yes, please see MOS Archives Page for more information.

Where can I find a list of all of the acronyms used on the MOS pages?

A list of Frequently used Acronyms has been compiled, more entries will be added.

When are you going to add more elements to the new MOS messages? When will they be complete?

For a full schedule of upcoming additions to the MAV, MEX, and MET messages, check the Change Log page.

Why aren't the products on your website always the most up-to-date?

These web pages are not considered operational, they are only monitored by us during normal working hours (M-F 7 am - 5:30 pm). As with any facility, we sometimes experience problems with our computers that cause the web pages to not be current. We encourage you to read the National Weather Service's Disclaimer and Privacy Policy.

When do the seasons change in your MOS equations?

It differs by element, model, and message.

Season Change Dates by Element and Product

Element GFS MAV NAM MET GFS MEX
Temperature 4/1 - 9/30
10/1 - 3/31
4/1 - 9/30
10/1 - 3/31
4/1 - 9/30
10/1 - 3/31
Ptype 9/1 - 5/31 9/1 - 5/31 9/1 - 5/31
Thunderstorms 10/16 - 3/15
3/16 - 6/30
7/1 - 10/15
4/1 - 9/30
10/1 - 3/31
10/16 - 3/15
3/16 - 6/30
7/1 - 10/15
All other Elements 4/1 - 9/30
10/1 - 5/31
4/1 - 9/30
10/1 - 3/31
4/1 - 9/30
10/1 - 3/31