Blacksburg VA (RNK) GPS Precipitable Water Project

Updated 9/12/01 by Steve Keighton (Science and Operations Officer)

This is an image of the GPS sensor near our office

 PW Monthly Climatology for RNK and GSO

  The Use of GPS Integrated Precipitable Water Measurements to Supplement WSR-88D Parameters in Determining the Potential for Flash Flood Producing Rainfall (PDF Format)


During the Summer (2000), the National Weather Service in Blacksburg, in cooperation with NOAA Forecast Systems Laboratory (Boulder), and Virginia Tech Dept of Civil Engineering, began a research effort to determine the impact of near realtime integrated precipitable water (IPW) measurements from a GPS sensor, on short term forecasting of flash flooding produced by convection. This has been approved as a COMET Partner's Project for FY 2001, titled "The Use of GPS Precipitable Water Measurements to Supplement WSR-88D Rainfall Estimates for Flash Flood Forecasting in Southwest Virginia". Specifically, we are comparing the temporal trends in the GPS IPW data with trends in convective activity in southwestern Virginia as observed by Doppler radar and satellite, to determine if short term trends or maximum values of PW provide any reliable signal in advance of flash flooding or rainfall rates that could produce flash flooding. We are comparing values of IPW with maximum observed radar reflectivity parameters and rainfall rate estimates, as well as observed rain rates at precipitation gages. We also plan on comparing the GPS IPW values with radiosonde measurements collected at the office, as well as values measured by the sounder instrument on the GOES-8 geostationary satellite.  Preliminary results show evidence of some correlation in GPS IPW trends with the maximum rain rates as measured by radar, but several more events need to be examined. More results will be posted this spring or summer.

Below are links to some of these data sets that are available on line.


Realtime GPS PW and Sfc Data (from FSL) (only works with I.E.)
- predicted orbit method
    - includes option to dowload ascii file by interactively choosing time window

GPS PW post-processed - 30 hours old (from FSL)
     - slightly more accurate, not realtime

Other GPS PW Data Displays (UCAR)

Map of GPS PW Network in US


GOES Sounder PW

GOES Derived Soundings - Choose RNK (NESDIS)

Latest GOES Sounder PW Image (Univ of Wisc - CIMSS)

GOES Sounder PW Loop (NESDIS)

Interactive GOES PW/LI/CAPE Trends (Univ of Wisc - CIMSS)

GOES Sounder PW 3-hr Trend Image (NESDIS)

00Z Raob - GOES Sounder PW Compare (Univ of Wisc - CIMSS)

12Z Raob - GOES Sounder PW Compare (Univ of Wisc - CIMSS)

Other GOES Sounder Products from NESDIS


GOES Images

Latest Eastern U.S. Visible Image (UCAR)

Latest Eastern U.S. IR Image (UCAR)