Ensemble Fun with Bufkit

During the summer of 2010, the Bufkit application was upgraded to view BUFR output from ensemble forecast models. Forecasters can view various ensemble members in the Skew-T display mode along with various indexes, the p-type nomogram, and other displays. In addition, forecasters can view various variables with time in the overview mode, including “plumes” of precipitation accumulation. One of the nice features of the ensemble display in Bufkit is the ability to toggle off and on various SREF members, either by model family, convective parameterization or perturbation type. Forecasters have used the capability to view and toggle off/on various SREF members to investigate the variability of QPF, 2m temperatures, and other output among ensemble members.

The image below shows the 2 meter temperature forecasts from the various members of the SREF for KRDU from the 20111231/15UTC run. This forecast cycle featured a developing eastern CONUS trough with fair weather and cold advection at KRDU.  Specifically, on Tuesday, 3 January, KRDU was forecast to experience clear skies, light winds, and good radiational cooling conditions.

The example above shows the unusual consistency within each the of the four SREF model families in how they forecast 2 meter temperatures, while also highlighting the variability between the various SREF families (ARW, Eta, NMM, and RSM). For example, the 5 RSM members all are consistently colder than the 16 other SREF members, especially during the morning, and most especially on Tuesday morning at around 600 AM. This is likely a result in some part from the general cold bias of the RSM/GFS along with the configuration of the RSM members. On the other hand, the 5 NMM members are consistently warmer than the other 16 SREF members on Tuesday morning. The plot also highlights times in which all of the guidance is more consistent, Sunday morning low temperatures for example. In this example, it can be argued that the period of time in which the unusual consistency within each the of the four SREF model families is present is indicative of times in which model configuration dominates.

It is worth noting that the capability to view ensemble BUFR output was briefly available and utilized for the High resolution Mid-Atlantic Ensemble (HME) that was in part supported by CSTAR.

More information on the SREF members is available in the table at the following link.


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