Example of NESDIS Snowfall Rate Product from Northern California Snow Event

Last winter, SPoRT collaborated with NESDIS to perform an evaluation of the a passive microwave snowfall rate (SFR) product.  The impact of the product on the operational process was very large, and a tremendous amount of feedback was generated.  This feedback was used to improve the product in 3 ways:

  1. Product latency has been reduced through use of direct broadcast datasets over CONUS
  2. Algorithm modifications have been performed to drop the limitation of cold air at the surface from 22F to 7F, meaning more snow will be detected in colder air masses
  3. The minimum threshold of detected snowfall was reduced from 0.1 to 0.04 mm/hr (liquid equivalent)

These modifications were based on direct feedback on limitations to the product noted by WFO participants last winter.

Because of the operational impact of the data of the first product iteration, and the great responsiveness by the product developers at NESDIS, SPoRT is again working with NESDIS and the WFOs to assess the next iteration of the SFR product.  An assessment is ongoing in Alaska and a CONUS assessment will begin in mid-January.

To whet everyone’s appetite about this upcoming assessment, we received the following input from Sheldon Kusselson, at the Satellite Analysis Branch, who is a strong forecaster advocate for the SFR product and has been an active participant in assessment of the SFR product:

A small success with low rates/small area of 0.04″/hr over the northern Sierras…Plumas/Sierra County  with SFR pass of I believe 2230z…and relayed that to the WFO Sacramento.  They responded, that they had some reports of snow down to 3200′ in Plumas County. A little south of Sierra County in Placer its around 5000′.  Then they came back 03z and mentioned 4″ of new snow at 3800 ft in Plumas County.  Noted a new 0010z pass that had max rates of 0.08″-0.09″/hr centered over the Plumas, Tehama, Butte, Sierra-Plumas County border area.   So this appeared to work out well for a small, but intense area in elevations above 3000′.

NESDIS SFR Product valid at 0057Z on 12 December 2014.  The navy blue coloration indicates over water regions where the SFR product will not be retrieved.  Notice the small-scale, high-intensity snowfall that is detected over NE California.

NESDIS SFR Product valid at 0057Z on 12 December 2014. The navy blue coloration indicates over water regions where the SFR product will not be retrieved; the grey coloration indicates the area of the satellite swath where no snowfall was detected. Notice the small-scale, high-intensity snowfall that is detected over NE California.

Thanks to Sheldon for pointing out this great example of the SFR product in elevated terrain where radar overshoot and beam blockage makes detection of falling precipitation challenging!

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