Monday, April 16, 2012

NWS Announces Significant Upgrade in Columbia, SC

The National Weather Service Forecast Office in Columbia, SC, announced today that the Doppler radar will be upgraded to dual polarization (or "dual-pol") beginning May 3rd.  It will take approximately a week for the upgrade during which time the radar will be inoperative.  Other area radars will be used to cover the Midlands in case of severe weather.  At News19 we will be using the Greenville, Atlanta, Wilmington, and Charleston radars in live mode to provide the coverage on the Max Storm Doppler Radar.  A composite radar will be used on our cable feed of the radar.

A minor inconvenience considering advantages of the system.   “This is the most significant upgrade to the nation’s weather radar network since Doppler radar was first installed in the early 1990s and is a significant step toward us becoming weather ready,” said Jack Hayes, director of NOAA’s National Weather Service. “Dual polarization technology provides significantly more information and clearer pictures of current weather conditions, helping National Weather Service meteorologists provide more accurate and timely forecasts."

A dual-pol radar at NOAA’s National Severe Storms Laboratory in Norman, Oklahoma, monitored this storm during the 2003 Thunderstorm Electrification and Lightning Experiment.  Image credit: Michael James, UCAR.

The development of the dual polarization is an outgrowth of decades of research at NCAR, Colorado State University (CSU), NOAA’s National Severe Storms Laboratory (NSSL), and elsewhere.  Tests were conducted at NSSL to evaluate the operational use of the dual -pol and development of the software needed for real-time observations.  According to Wikipedia the first operational dual-pol Doppler radar was at Vance Air Force Base near Enid, OK, in early 2011.

What is dual polarization?

Image credit: NOAA\ROC.
Conventional Doppler radar transmits a polarized beam only in the horizontal plane while the dual-pol Doppler radar transmits an alternating polarized beam horizontally and vertically.  The advantage of the dual-pol radar is that it can distinguish between different types of precipitation making rainfall estimates far better.  Hail size estimates will also be better improving the warnings that are issued.

The advantages are not confined to severe weather.  The ability to distinguish between rain and snow will allow forecasters and broadcasters to better delineate areas getting rain from those receiving snow.  It will also help determine the snow level which is important for aviation and mountain areas.

Image credit: WLTX-TV.
There will also be advantages in severe weather.  In the tornado outbreak this past weekend the dual-pol Doppler radar in Wichita was able to distinguish debris in the air confirming the location of the tornado.  This will be extremely useful in the Southeast where tornadoes can be wrapped in rain making them invisible to those outside the storm.

A few of the radars in the region are already dual-pol.  The Atlanta radar is a dual-pol and has been operational since last December.  The Morristown, TN, radar and the radar near Macon, GA, also dual-pol.

I will be more on dual polarization in the near future.