Beginning in the morning hours of 22 January 2016, rain began to change to snow across Mississippi, Tennessee, and Alabama. The NESDIS Snowfall Rate, which is currently being evaluated by a handful of Weather Forecast Offices, has the ability to differentiate rain from snow. This ability was particularly important for the large winter storm impacting much of the eastern half of the United States. The animation below shows the 10:1 Solid SFR Product with METAR station observations indicating temperatures and precipitation.
The animation shows the evolution of snow across the area beginning with snow in Western Tennessee and Eastern Mississippi at around 1200 UTC (6:00a local time). Also of note at that same time is that the SFR Product indicates relatively heavy snow (~1.5 in./hr. solid snow) directly over the Nashville area; however, the METAR site at the airport is still reporting rain. In the following hour (1300 UTC; not shown in the loop here because there was no SFR product valid near 1300 UTC) Nashville was reporting snow. Thus, the SFR product was seeing in-cloud snow in that area that began to reach the ground within an hour of the observation. This is one way forecasters can use the product to view in-cloud snow to determine the potential for snow to reach the ground.
Later in the period, a similar set up appears in the Huntsville area at the Madison County Executive Airport (KMDQ). The 1853 UTC SFR product shows light snow over Madison County, but the 1900 UTC METAR was not yet reporting any snow. However, the 2000 UTC METAR showed snow beginning to fall across the Huntsville area. The change over to snow falling across Western Madison county into Central Madison county was between 1830 and 1900 UTC, verified as I drove home from work.
The NESDIS SFR product will continue to be evaluated as blizzard conditions begin to set up along parts of the East Coast.