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Product Description

Base velocity is derived by evaluating the 'doppler shift' of the returned signal. If the target object is moving, the component of that target's velocity that is parallel to the radar beam will result in a phase shift of the return. That is to say that the radar is only capable of determining the velocity of an object in one dimension; either toward or away from the radar. A shift to higher frequencies indicates a component of the targets velocity is moving toward the radar and are often displayed in varying shades of green. A shift to lower frequencies indicates a component of the targets velocity is moving away from the radar and are displayed in varying shades of red. Motionless objects or objects moving exactly perpendicular to the radar beam will not result in any detectable doppler shift and will be evaluated as having a velocity of 'zero'. Velocities at or near zero often are displayed in shades of grey and white. Because the radar scans radially in all directions there is no wind flow pattern that will not result in some (nearly) continuous strip of zero or near zero velocities. This phenomenon results in a feature referred to as the zero-isodop (isodop referring to a line of constant doppler shift). The shape of the zero-isodop and the fact that the radar beam increases in altitude above the ground further from the radar can be used to infer characteristics about the vertical wind profile through a slice of the lower atmosphere. For further information, explore the following Meted module from UCAR and advancing to the 'Doppler Velocity Measurements' section: Go here

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Radar Status Message

137 NOUS63 KSGF 221557 FTMSGF Message Date: Oct 22 2025 15:57:53 radar back in service jdh

For further information, check the following twitter accounts for periodic updates on product generation status and website improvements; @CoDWXData and @CODMeteorology. Your feedback is always appreciated, so feel free to respond to tweets or send us an email using our Feedback page.

Dual-Pol Radar Site Selection

Change Map Region: CONUS ALASKA HAWAII Addtional Sites: Guam Puerto Rico
Change Map Type: Radar Radar + Warnings

Active Severe Weather Warnings

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Type Counties Affected Tornado Status Hail Size Wind Speed Available Radar(s) Issued by Issuance Time Expire Time

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We were unable to generate this product. This can happen for a number of different reasons. Be sure to check the status of SGF here and/or here. If the site status is normal and this site or product suffers a continuous outage, keep us aware of it by using our Feedback Page.