1. National Weather Association
42nd Meeting September 17, 2017
An Introduction to Real Time Aircraft Soundings for Broadcast Meteorologists and Storm Chasers
Rich Mamrosh – NWS Green Bay, Wisconsin

2. Introduction
The NWS provides public access to real time soundings and flight level data from 135 UPS and Southwest Airlines aircraft.
The aircraft are equipped with water vapor sensors that produce around 1,000 soundings each day.
The data are being provided by MADIS in netCDF format and eventually via interactive web page.
This presentation will begin with a short history of aircraft weather data, followed by forecast applications and ideas for broadcast meteorologists and storm chasers.

3. History of Aircraft Weather Data
Aircraft have been used as platforms for collecting meteorological data since the dawn of aviation.
Installation of modern communications systems allow commercial aircraft to automatically transmit meteorological data.
An increasing number of airlines around the world share wind and temperature data with the NWS and other national meteorological services.
A meteorologist collects weather
data from instruments attached
to an aircraft in 1919.

4. History of Aircraft Weather Data
There are nearly one million temperature and wind reports from around the world each day.
Average daily AMDAR data since 2007
These data are used in the HRRR, NAM, GFS, and ECMWF models.
Global AMDAR data for 24 hour period

5. History of the WVSS Program
In order to complement wind and temperature data, UPS Airlines and the NWS partnered to install water vapor sensors on six UPS 757 aircraft between 1997 and 1999.
The units measured relative humidity using a thin film capacitor similar to NWS radiosondes. It was called the “Water Vapor Sensing System”.
Air intake for WVSS system
UPS Airlines 757 aircraft

6. History of the WVSS Program
Field studies showed that the WVSS compared favorably to radiosondes, but the sensors needed to be replaced too frequently to be used on commercial airlines.
WVSS Sounding from May 1997
Data from 2001 comparison
Next – WVSS-II

7. History of the WVSS Program
2004-Present
A new sensor was developed by Spectrasensors that uses a diode laser to measure water vapor mixing ratio. It requires little or no maintenance and is of higher quality.
The WVSS-II was installed on twenty five UPS aircraft between 2004 and 2005.
Components of WVSS-II system
WVSS-II Diode Laser

8. History of the WVSS Program
2004-Present
Field experiments determined that WVSS-II compared very favorably to high quality radiosonde data, prompting the purchase of additional sensors.
CIMSS mobile sounding unit
Radiosonde/WVSS-II comparison

9. History of the WVSS Program
There are now 135 UPS and Southwest Airlines aircraft with WVSS-II sensors.
The NWS currently purchases these data from Rockwell Collins, who owns the sensors and manages the network.
This partnership makes the data publically available.
WVSS-II data for 24 hours ending at 10z
August 30, 2017.

10. History of the WVSS Program
WVSS-II is different from TAMDAR
It should be noted that the NWS participated in a NASA sponsored experiment to collect relative humidity and other data from commercial aircraft called TAMDAR (Tropospheric Airborne Meteorological Data Report) from
Panasonic Aviation Systems is now the sole owner and provider of TAMDAR data.
The NWS currently purchases selected TAMDAR data, though they are not publicly available.
Next – Data Acquisition

11. Data Acquisition - netCDF
Request a MADIS account (no cost) at
Access to all WVSS-II data is available in netCDF format at
If you only want the sounding data, it is at
The data can be used to run local models, produce various forecast products and create custom sounding display pages.

12. Broadcast Meteorologists
If they can download the netCDF data and produce soundings, they can use the soundings to refine forecasts for their broadcast region.
Graphically show the state of the atmosphere as it effects convective initiation, formation of fog, transition from rain to snow, etc.
Educate their audience on how upper air data are used to forecast various weather phenomena.

13. Broadcast Meteorologists - Convection
NWS meteorologists have utilized WVSS-II to determine convective initiation, intensity, and heavy rain potential.
Broadcast meteorologists can now do the same.
Here is an example of how the Houston NWS staff used WVSS-II for a convective event.

14. Broadcast Meteorologists - Convection
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1026 AM CDT THU JUL
.DISCUSSION...
AMDAR SOUNDINGS SUGGEST WE WILL HAVE THUNDERSTORM DEVELOPMENT TODAY WITH LIFTED INDICES AROUND -5 AND CAPES 2000 TO 3000 J/KG ONCE CONVECTIVE TEMPS ARE REACHED (AROUND 90F). SOUNDINGS SHOW VERY LITTLE WIND OR WIND SHEAR SO WE SHOULD HAVE SLOW MOVING PULSE TYPE STORMS.

15. Broadcast Meteorologists - Convection
Soundings
can be
modified to
expected
afternoon
conditions.
An afternoon
temperature
of 90F (32C)
is sufficient
to break the
cap and
convection
to begin.
Note stability
Indices.
The extremely
light wind field favors slow moving
storms with
little or no
organization
This slide shows an unstable atmosphere once the temperature reaches 90F, along with very weak winds that favor slow moving storms with heavy rain.
WVSS-II Sounding from HOU at 1649Z July 3, 2014

16. Broadcast Meteorologists - Convection
This is a radar animation that shows thunderstorms forming as the temperature reaches 90F. They move slowly and produce heavy rains.
Temperatures in Houston rose to 90F at noon, and slow moving thunderstorms began, just as the WVSS-II soundings suggested.
Next – Weakening Thunderstorm

17. Broadcast Meteorologists - Convection
A line of strong thunderstorms is moving towards Tulsa, but weakening
A WVSS-II sounding from
Tulsa shows why
Tulsa, OK
This slide shows a radar loop of a line of thunderstorms approaching northeast Oklahoma. The WVSS-II sounding from Tulsa suggests that the storms will weaken as they move into a more stable environment.
Prompting this “Tweet”
From NWS Tulsa
WVSS-II sounding reveals a
capped, stable atmosphere.

18. Broadcast Meteorologists - Precip. Type
Broadcast meteorologists can use the soundings to explain precipitation type to their audience.
This animation shows environments that produce different types of precipitation, and aircraft sounding examples of each. Click through the four types.

19. Storm Chasers and Spotters
Storm chasers and well educated spotters can use the soundings to determine the current state of the atmosphere, including stability, shear, temperatures aloft, and water vapor content.
The soundings will complement the NWS special 18z radiosonde launches.
The availability of WVSS-II soundings throughout the day and night increases their utility.

20. Storm Chasers and Spotters
Strong low level winds east of the remnants of Hurricane Harvey were expected to produce sufficient shear for severe thunderstorms over the Southeastern States, despite modest instability.
The 1630Z SPC Day 1 outlook for August 31, 2017 did an excellent job of forecasting the location of severe storms later in the day.
SPC Day 1 Outlook 1630Z
Preliminary Damage Reports

21. Storm Chasers and Spotters
The NWS launched a supplemental radiosonde in Birmingham at 18z, as did Eglin AFB in Florida.
In addition to the radiosondes, WVSS-II soundings were available at Birmingham, Tallahassee, Atlanta, Columbia, Nashville, and Jacksonville.
18z special radiosonde
launches denoted by stars
SPC Day 1 Outlook 1630Z
WVSS-II soundings available

22. Storm Chasers and Spotters
Additional WVSS-II
soundings were
available between
18z and the next
regular radiosonde
launches at 00Z
Atlanta (5)
Birmingham (4)
Columbia
Jacksonville
Memphis
Nashville (6)
Tallahassee
This slide shows that 19 WVSS-II soundings were available between 19z and 24z August 31st. Soundings such as these will be very useful to storm chasers and spotters
Flight paths of WVSS-II aircraft 19-24z 8/31/2017

23. WVSS-II Future Plans and Ideas
The NWS intends to expand the number of WVSS-II equipped aircraft as funding permits.
Aircraft that serve smaller airports in the Plains and Rockies are especially desirable.
Aircraft based observations are a very important data source, as the primary source of upper air data come from radiosondes, whose spatial and temporal resolution is less than ideal. In addition, there are major airports distant from any radiosondes. These airports have found aircraft data to be crucial to their forecast efforts.
Airports with WVSS-II soundings for 24 hours ending at 09z December 31, 2014.

24. Suggestions
Broadcast meteorologists could ask their service providers to produce TV ready WVSS-II graphics from netCDF data.
This graphic could show why there is freezing rain is being reported at the surface.
10,000’
8,000’
6,000’
4,000’
2,000’
Surface

25. Suggestions
Storm chaser web pages and the SPC could provide real time soundings and use WVSS-II soundings for case studies.

26. Suggestions
An application that displays soundings on smart phones would be very valuable to storm chasers and spotters.

27. WVSS-II Resources NWS AMDAR Program Curtis Marshall
MADIS WVSS-II Web Page
MADIS netCDF Data
Forecast Applications
Rich Mamrosh
WVSS-II Sensor Details
Bryce Ford
ARINC Rockwell Collins – airline and network coordination
Short video that describes the WVSS-II program
Aircraft data course from COMET (free registration)

28. Thank You Rich Mamrosh National Weather Service 2485 South Point Road
Green Bay, WI 54313
(920)