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  1-minute ASOS Data

1-minute ASOS Data



From February 10, 2009 - July 29, 2011 MADIS received 1 minute experimental observations from select FAA Automated Surface Observing System (ASOS) stations and Automated Weather Observing System (AWOS) stations. The data received during this time period was from an experimental feed and ASOS/AWOS observations were stored every 5 minutes.

From July 30, 2011 - October 26, 2015 the MADIS team worked with the FAA to establish an operational feed of this data from the FAA Weather Messaging Switching Center Replacement (WMSCR) systems to MADIS. No data is available during this period.

On October 27, 2015 the operational feed (FAA Weather Message Switching Center Replacement System (WMSCR)) to MADIS development systems at GSD went live, providing 1-minute observations but only 5-minute time stamped observations were stored, i.e., data time stamped as valid on the 0,5,10,...,50,55 minute marks. MADIS started processing and handling all 1 minute observations in November 2017.

Although originally referred to as HF-METAR data, the observations are now referred to as 1-minute ASOS data to differentiate them from METAR observations. 1-minute ASOS, also known as One Minute Observations (OMO), are binary messages that do not conform to the METAR data standard (FMH1) and should not be considered to be METAR observations.

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Data Schedule

Data arrive on a continuous, asynchronous schedule, and the current and previous hour's data are processed every 5 minutes. Data from this feed are stored in hourly MADIS files with observations starting at the top of the hour and ending at 59 minutes into the hour (e.g., the 0000 file covers 0000 - 0059).

Data that arrive after 2 hours following the time of the observation are processed in a "data recovery" mode, where once a day batch processing is performed to reprocess data that are 35 days, 7 days, and 1 day old. These data are available with all communications methods supported by MADIS except for ldm.


Typical daily volume for all MADIS datasets can be seen here.


No restrictions. All observations are publicly accessible.

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Last updated 15 March 2017