Frequently Asked Questions

What is CORAD?

CORAD (short for the Corsicana Radar) is a non-profit organization located just outside Corsicana, TX. We were incorporated under the name Weather Radar Warning System, Inc. as a 501(c)(3) in 197?. Our mission is to provide real-time severe weather radar data to the general public in Corsicana, Navarro County, and the surrounding area.

Are you affiliated with the City of Corsicana or Navarro County government?

CORAD is not a part of any governmental agency. We operate in cooperation with the Navarro County Office of Emergency Management for severe weather surveillance, warning to the general public, and storm spotter coordination through the OEM.

Where does CORAD get funding?

The initial funding Corsicana Radar came from the Navarro Community Foundation, established in 1938 by Frank Neal Drane, in Corsicana, TX. Today CORAD gratefully receives funding from the City of Corsicana and Navarro County for operating costs, maintenance and upgrades.

Who are you guys? Does anybody get paid?

We are a group of people with a passion for severe weather, radar technology, and a sense of community service. While we have a lot of experience operating and interpreting radar displays, we are NOT professional meteorologists (although one of our volunteers plans on becoming one).  Nobody is paid, we are an all-volunteer operation. Check our Volunteer page for more information on the people that make CORAD work.

You just aggregate radar imagery from the National Weather Service, right? You don't actually have a radar, do you?

We have two radars, one primary and one backup.

Our primary radar is a modified Texas Instruments ASR-5. Manufactured during the 1970s, the ASR-5 is a pulse-modulated S-Band Doppler radar operating at 2925Mhz with 425kW peak power. The ASR-5 was used throughout the United States by the FAA for air traffic control at civilian airports and at US Military installations (under the designation AN/FPN-47) until the early 1990s. Our ASR-5 is modified for weather observation.

Some quick specifications:

    • Frequency:                                : 2925Mhz
    • Pulse Repetition Frequency   : 250Hz for general search and 1000Hz for velocity mode
    • Pulse Width:                             : 0.833μs
    • Peak Power                              : 425kW
    • Antenna Beamwidth               : 1.2°
    • Range Resolution                    : ~150m


Our backup radar is a WSR-74C C-Band weather radar manufactured by Enterprise Electronics. This radar was procured from the National Weather Service Office in Waco, TX in the early 1990s after being decommissioned and replaced by the NEXRAD system. We have this radar in case of failure of the primary and so we can develop and test new features without taking the primary offline.

Do you run the radar all the time?

No. To minimize operating costs and wear and tear we only operate the radar during severe weather events. CORAD personnel make every effort to be here for all weather events, but as volunteers we have jobs and outside responsibilities that occasionally prevent us from being here during storms.

What's the point of having a local radar when the National Weather Service has a multi-million dollar nationwide system?

Two reasons:

    1. Time Delay: There is a 6-10 minute delay in the NEXRAD system between detection of a tornado and warning to the public. Anybody who has survived a tornado knows that, even in that short amount of time, great destruction and loss of life can happen.
    2. Earth Curvature: NEXRAD radars scan at fixed elevations called tilt sequences. The nearest NEXRAD site is 50 nautical miles away in Burleson, TX. With a minimum tilt sequence elevation of 0.5°, the lowest altitude that NEXRAD can detect rotation (and hence tornadoes) in the Corsicana area is about 4000 feet above ground level. Many small-scale tornadoes form below this altitude.


CORAD fills this time and space gap for Navarro County by sector-scanning storms back and forth near the earth’s surface and streaming live in real time to the general public. We can detect tornadoes that are too short-lived or too low to be detected by the NEXRAD system. 

This is NOT a criticism NEXRAD in any way. NEXRAD is without a doubt the best weather radar system in the world. It is simply inevitable that an automated nationwide radar system that is tasked with covering such a large geographic area will have blind spots. CORAD aims to fill these blind spots for our area.

How should the citizens of Navarro County use CORAD?

For official watch and warning information and the big weather picture, use the links on our main page to the Navarro County OEM and National Weather Service NEXRAD feeds. Watch our live stream when storms are imminent in your part of Navarro County. If you want to know if a storm will hit your area, use the National Weather Service. If you want to know if a storm will hit your house, use CORAD.

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