News and Notes

One of the seemingly unique archives maintained by the IEM is one of NWS Terminal Aerodome Forecasts (TAF)s. An example TAF looks like so:

FTUS42 KFFC 131551 AAB
TAFATL
TAF AMD
KATL 131551Z 1316/1418 09007KT P6SM FEW250
     FM140000 12003KT P6SM SCT250
     FM141600 14005KT P6SM SCT150=

A user of this archive requested the tracking of "Amendment" status, which the IEM was previously not doing. In the example above, this is denoted as TAF AMD. Support for this was added, but it will take a few days to reprocess the archive to include this attribute within the download service and various web services. Whilst adding web service support for this, the taf overview got some interesting updates and this news item intends to advertise those changes.

Newly supported TAF overview request examples

Provide GeoJSON of all most recently issued TAFs valid at 12 UTC on 25 Dec 2025
https://mesonet.agron.iastate.edu/api/1/nws/taf_overview.geojson?at=2025-12-25T12:00:00Z
This would return the most current issued TAF at or prior to the given UTC timestamp.

Provide JSON of available TAFs for Des Moines during July 2012.
https://mesonet.agron.iastate.edu/api/1/nws/taf_overview.json?station=KDSM&sts=2012-07-01&ets=2012-08-01
This returns all TAF metadata that can be used for subsequent queries to get an individual TAF.

Provide a CSV of all available TAFs for 15 December 2021 (UTC)
https://mesonet.agron.iastate.edu/api/1/nws/taf_overview.txt?sts=2021-12-15&ets=2021-12-16
Requests like these are limited to a 10 day period. The response seqnumber value orders the TAFs descending in time for a given station.

Hopefully folks find this useful and please always send bug reports and feedback our way!

One of the seemingly internet-unique archives that the IEM maintains is a parsed dataset of Terminal Aerodome Forecasts (TAFs). TAFs are issued by the National Weather Service (NWS) as aviation specific short term forecasts at many airports. The raw forecast text looks like:

FTUS43 KMPX 220156 AAA
TAFSTC
TAF AMD
KSTC 220156Z 2202/2224 17005KT P6SM BKN050
      TEMPO 2202/2204 -SHRA
     FM220400 18005KT P6SM SCT250 PROB30 2210/2215 4SM -TSRA
      OVC035CB
     FM221500 27010KT P6SM OVC050=

A review of the IEM's TAF processing found some gaps with how the TEMPO and PROB30 fields were stored within the database. These have hopefully now been corrected with an additional field now available within the download called ftype, which delineates between the observation, forecast, tempo, and probability data types.

As always, please send any feedback on this and how the archive could be more useful for your needs!

To support aviation and meteorology research needs, the IEM attempts to curate an archive of National Weather Service (NWS) Terminal Aerodome Forecasts (TAF)s. TAFs are text products that look a lot like METARs, for example a current TAF for Des Moines, IA (KDSM):

FTUS43 KDMX 221343 AAA
TAFDSM
TAF AMD
KDSM 221343Z 2214/2312 28011KT P6SM BKN120
     FM221500 27013G21KT P6SM BKN120
     FM222200 27008KT P6SM FEW120
     FM230300 15005KT P6SM FEW250=

A user of the available downloadable archive found that the IEM archive had a massive hole between 1 Jan 2010 and 4 Apr 2015 for all TAF sites. It is unclear what happened(^TM), but the raw text archive of this product was missing as well from the IEM NWS Text Product Archives.

So this hole was repaired by back-filling the raw text from the NCEI SRRS and reprocessing those historical TAFs into the archive database.

As always, please let me know when you find variances like these within the IEM archives.