Snow Advisory Event on Jan 25 2014

Radar_1106UTC_012514SFR_1120UTC_012514

On Jan 25 2014, a mid-level shortwave moved across the region generating light to moderate snow. I have included screen captures of the 1118 UTC regional radar mosaic and surface observations…along with a 1120 UTC Snowfall Rate Product and surface observations.

It looks like the SFR product did not detect all of the snow that was falling around 11 UTC. But the misses can generally be described as either (1) the surface temperatures being too cold or (2) the probabilistic model, that is part of the calulations, indicating probabilities that were too low to determine if there was snow.

Once you know all of the details on how the product is calculated, I think this product did a good job at detailing where the snowfall was occurring.

The highest snowfall rates indicated by this image was around 0.3 to 0.5 inches which seems to be representative of what was occurring.

3 thoughts on “Snow Advisory Event on Jan 25 2014

  1. Thanks for this evaluation, Jeffrey! This is outstanding. I think your assessment is correct that the colder temperatures are affecting the detection of much of the snowfall over Ohio, but the bands over the OH/IN/KY Tri-state area and OH/WV border appear to be pretty representative, as you have indicated. This is a great example of using the radar, SFR product, and snowfall reports together to get a complete picture of a snowfall event.

  2. The Snowfall Rate Product provided values as a snow-water equivalent. Were the values you were getting 0.03″-0.05″/hr and you converted it 10:1 to snowfall rate? Also, snowfall rate product is detecting snow in the clouds that may not yet have reached the ground or may have never reached the ground…so caution for that too with the product. I would also include the use of satellite IR and when available a VIS image as well and then follow the more latent and frequent GOES imagery for speed and trends along with radar. Good job…thid information will help us improve the product and help forecasters know how to use the product

    • The units of the SFR product, as it is displayed in our AWIPS, are mm/hr. So I converted mm/hr to in/hr. This value was then converted to snowfall rates/hour by using an estimated Snow-to-Liquid ratio. This ratio was calculated from a routine that uses BUFKIT soundings and generates the rates looking at the entire sounding, not just the surface temperatures. It was developed by Dan Cobb, who is currently the MIC at the NWS office in Grand Rapids MI.

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