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ASOS Map Link:


Below is the link to the ASOS Map that shows METAR Data that is provided from the Aviation Weather Center. 




Wind Sensor Replacement

September 2023 | SLEP Initiative


The manufacturer of the ASOS Ice Free Wind Sensor, the Vaisala 425NWS, announced in 2016 that 425NWS repair parts were no longer available, rendering the sensor obsolete. The awarded logistics replacement to the NWS-425 is the Vaisala WMT-702 with heated tip transducers. Testing was performed on the WMT702 at the Sterling Field Support Center and an in-depth data evaluation was conducted at twelve operational ASOS sites in lieu of a formal Operational Test & Evaluation (OT&E). The objectives of the evaluation were to evaluate the installation of the sensor, the integrity of the wind data, the representativeness of the wind data as well as the performance of WMT702-equipped ASOS. Based on the findings of this  evaluation, it was recommended that the WMT702 be deployed as-needed across the ASOS network. Final procurement of sufficient sensors to deploy to all ASOS sites was completed during January of 2023 and the full population of ASOS sites should have a new wind sensor by December 31, 2023.


Temperature and Dew Point Sensor Upgrade

August 2023 | SLEP Initiative


ASOS is a Tri-Agency Program with the Department of Commerce (DOC), Department of Transportation (DOT) and Department of Defense (DoD). Sustainment activities for Sensors From 2022 - 2027 must be coordinated across all three agencies. The Temperature and Relative Humidity sensors presently fielded with the ASOS, include the DTS-1 and the HO-83/1088, whose designs are well over 20 years old. The DTS-1 is no longer supported by Vaisala as of August 31, 2020 and will be unable to be repaired beyond August 2021.  Additionally, the HO-83/1088, is very expensive to maintain and has known reliability issues. 

The ASOS Program has an approved temperature and dew point sensor replacement design using the HMP-155 dual probe; one for Ta (Air temperature) and one for Td (dew point Temperature). The sensor probes sense Ta and Relative Humidity to calculate the Td. Some refer to this effort as the TRH project as well. This design is undergoing procurement and is expected to be in operational test and evaluation in the fall of 2023. Updates to this project will be posted as they become available.


Update: November 20,2023


The NWS announced the commencement of the Air and Dew Point Temperature sensor replacement Operational Test and Evaluation in this public statement. The ASOS Program is now in an Operational Test and Evaluation posture, the following schedule is provided for information.

Site Install Date
Annapolis, MD NAK, Eastern Region Nov 28, 2023
Garrison, ND N60 Central Region Dec 06, 2023
Austin, TX ATT, Southern Region Dec 06, 2023


The first three sites are being installed in between FAA mandated maintenance moratoriums due to the Thanksgiving and Christmas Holidays that will provide the opportunity for the NWS to monitor these three sites through the month of December 2023. The schedule picks back up in January.

Site Install Date
Portage, AK POR, Alaska Region Jan 09, 2024
Mount Holly, NJ VAY, Eastern Region Jan 09, 2024
Peachtree City, GA Peachtree City, GA Jan 10, 2024
Palmer, AK PAQ, Alaska Region Jan 10, 2024
Lawrence, KS LWC, Central Region Jan 16, 2024
Roanoke, VA ROA, Eastern Region Jan 16, 2024
Charleston, SC CHS, Eastern Region Jan 17, 2024
Cherry Point, NC NIS, Navy Region Jan 17, 2024
Las Vegas, NV LAS, Western Region Jan 23, 2024
Salt Lake City, UT SLC, Western Region Jan 23, 2024
Seattle, WA SEA, Western Region Jan 24, 2024


The dates provided are target dates with no guarantees of successful installation. Additional information will be provided as it becomes available.


Update: Jan 8, 2024


Data errors at the first operational test site required the rollback of the HMP-155E Temp/Dew sensor to the legacy 1088/DTS1 sensors at Annapolis, MD (NAK). This was successfully completed Thursday, December 14, 2023. NAK was fully operational with the legacy sensors as of the 1754 UTC METAR.

Resumption of the Temp/Dew Operational Test will be announced in the near future.

ASOS Service Life Extension Program (SLEP)

August 2023 | ASOS Program Initiative

For ASOS to remain viable as a mission critical system for the next 20 years, a technology refresh is required. The Service Life Extension Program (SLEP) for ASOS has been established for this purpose. This program facilitates the purchase of new ASOS Acquisition Control Units (ACU) and Data Collection Package (DCP) hardware. These acquisitions along with the development of associated software and information technology provide the necessary means to ensure that aviation weather information is being properly collected well into the future. The project is a tri-Agency undertaking between the Department of Transportation, Federal Aviation Administration, the Department of Commerce, NOAA National Weather Service, and the Department of the Defense, US Navy.


ACU/DCP Replacement

August 2023 | SLEP Initiative

The Legacy ASOS fielded in the 1990s was built around four main component groups: the Acquisition Control Unit , ACU, the Data Collection Package, DCP, the weather sensor group, and the system peripherals. In some deployments, however, the ACU and DCP are combined into a Single Cabinet ASOS (SCA) where components from both are located in one single outdoor enclosure. The heart of the current ASOS system, the ACU, controls the functions of all other system components. The ACU receives and processes weather information either from sensors directly attached or from one or more DCPs with attached weather sensor groups. The upgrade of the ACU and DCP hardware will allow for an extended system lifespan in addition to expanding the functionality and reliability of the system as a whole.

Currently, the project is entering the System Acceptance Testing phase during the fall of 2023 and will transition into Operational Test and Evaluation during the Spring of 2024. Updates to the ACU /DCP replacement project will be posted as they become available.


Campbell Scientific Inc. Meteorological Garden


The ASOS EDM at CSI Headquarters, Logan, UT

Campbell Scientific is the manufacturer for the upgraded ASOS Acquisition Control Unit, Data Collection Package and the Single Cabinet ASOS (ACU/DCP/SCA) for the National Weather Service, Automated Surface Observation System. Campbell Scientific has been a trusted leader in measurement systems for over 40 years.

Campbell Scientific, Inc. is the original equipment manufacturer of the upgraded ASOS ACU/DCP/SCA. ASOS sites with this upgrade are dubbed at “ASOS 2.0” sites.  As the OEM, CSI has replicated an ASOS at their headquarters in Logan, UT for use as a representative Engineering Development Model (EDM). Here are some pictures of the mock up of the CSI meteorological “garden” that will be used to support the NWS in system integration and engineering baseline synchronization.

CSI Website
CSI Photo Gallery

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