National Weather Service Weather Forecast Office

The Tallahassee WSR-88D radar (site: KTLH) is scheduled to undergo an upgrade to dual-polarization technology beginning October 19, 2012. The radar should be out of service temporarily for approximately 7 to 10 days while the new technology is being installed. The entire fleet of WSR-88Ds (Weather Surveillance Radar -1988 Doppler) is scheduled for the dual pol upgrade. Installations began over the past year, and should finish in the spring of 2013.

This upgrade in technology will increase the National Weather Services capabilities to better estimate rainfall, hail and other severe weather threats.

While the radar is out of service, alternate radars around the area include:

• Fort Rucker, Alabama (site: KEOX) - located in Dale County
• Eglin Air Force Base, Florida (site: KEVX) - located in Walton County
• Moody Air Force Base, Georgia (site: KVAX) - located in Lanier County

All three of these locations have yet to receive the dual pol upgrade yet, and are scheduled to get upgraded in the first few months of 2013. Here is the deployment schedule from the Radar Operations Center (ROC).

Basic Information

So what exactly is dual-polarization technology? Here's a quick 1-minute video from the NOAA Weather Partners with a brief explanation:

Essentially, in the past the doppler radar would transmit and receive horizontal pulses only. Therefore, the radar would only measure the horizontal dimensions of a target. The upgrade will allow the radar to transmit and receive both horizontal and vertical pulses, which will provide more information on the size, shape, and variety of targets that are in the atmosphere. This can allow meteorologists who are trained in interpreting the radar data to distinguish between different types of hydrometeors - hail, rain drops, snow and ice crystals, and non-meteorological targets like insects.

Legacy NWS Radar	Dual-Polarization Radar

Benefits of Dual Pol

• Ability to differentiate between large and small rain drops.
• Ability to differentiate between types of hydrometeors: hail, melting hail, rain, snow (ice crystals), and sleet.
• Improved detection of non-meteorological targets such as ground clutter, chaff, insects, birds, and tornado debris.
• Identification of the melting layer aloft.
• There may also be some improved accuracy of precipitation estimates.

In the following YouTube video, Paul Schlatter, a meteorologist with the National Weather Service, discusses how the introduction of dual-polarization radar technology will helping improve the identification of tornadoes through tornadic debris signatures.

Note that while dual-polarization radar provides specific information about the location of a tornado, it does not provide additional information about where or when a tornado will form ahead of time.

Resources To Learn More

The NWS Warning Decision Training Branch (WDTB) has compiled a page with training resources. These training materials are varied so that you can choose to view documents and modules that will describe dual-polarization technology for users of different technical expertise. You can view that website by clicking here.

We have also listed some of the resources below so that you can jump to more specific areas:

• Frequently Asked Questions (PDF, NOAA Communications and External Affairs Office)
• Deployment Schedule (PDF, Radar Operations Center)
• Installation Status and Map (PDF, Radar Operations Center)
• Training for non-NWS Meteorologists (WDTB)
• Training for non-Meteorologists and general users - bottom of page (WDTB)
• Quick Reference Guide for Media (PDF, WDTB)
• Decision Aid and Flip Chart (PDF, WDTB)
• National Severe Storms Lab Dual Pol Page (NSSL)