On 29-30 January 2010, a major storm impacted the Southeastern U.S. with significant amounts of frozen precipitation. Heavy snow fell from Oklahoma across Arkansas, Tennessee, and into North Carolina and Virginia. Snowfall of over a foot occurred on the northern fringe of the storm, while freezing rain and sleet affected portions of the Tennessee Valley. Mainly rain occurred further south. The morning surface analysis from the daily weather map series is shown in Figure 1. The 24-hour accumulated precipitation ending Saturday 1200 UTC 30 January is given in Figure 2.
Figure 3 displays a sample snow water equivalent image from the real-time Land Information System (LIS) run at SPoRT. The graphic depicts widespread areas of > 0.25″ liquid equivalent of the snowpack extending in a swath from Oklahoma into the Carolinas. The LIS shows that portions of NE Arkansas and western Tennessee north of Memphis had the highest water equivalent amounts of 1-2″ or more. This type of output could aid forecasters in diagnosing the risks for flooding during a rapid snowmelt situation.
A little background on the LIS: The Land Information System is a NASA-developed software framework that can run a variety of Land Surface Models (LSMs) with a user-specified atmospheric input dataset. The atmospheric input or “forcings” provide the variables required to integrate the LSMs. In the SPoRT implementation of LIS, the Noah LSM (same scheme as used in the operational NAM model) is run at 3-km grid spacing 4x per day on the domain shown in Figure 3. The atmospheric forcings come from a combination of short-term forecasts from the 0.47 degree Global Data Assimilation System, hourly 1/8th degree North American Land Data Assimilation System analyses created at NCEP, and hourly 4.8 km radar+gauge Stage IV precipitation analyses. The LIS is currently configured to output hourly GRIB-1 files that are posted to an anonymous ftp site. The data can be used for local modeling applications, and could also be used for diagnostic purposes.