High-Resolution 3D Wind Analysis 2009

To provide end users, especially NWS forecasters, easy-to-use height-resolution wind products that can help improve decision making, the Analysis and Prediction Thrust, in close collaboration with the Sensing Thrust and the End User Group, has continuously produced and presented real time 400m-resolution low-level wind analyses that integrate the radial velocity data from the CASA and NEXRAD radars as well as from other sources of wind information. In spring of 2009 the analysis was able to take advantage of multiple Doppler velocity coverage in the IP1 domain, and produced the best possible, spatially continuous analyses. On 14 May 2009, an EF-2 tornado hit Anadarko, OK.  The strong damaging winds produced several million dollars worth of damage, and two-thirds of the town was without power for at least one day.  The following figure shows the 50-minute evolution of low-level wind fields that covers the period of tornado touchdown. At 0200 UTC (upper left panel), a weak vortex was observed and this alerted the forecasters that a possible strong vortex could emerge. Ten minutes later, the vortex became much stronger (middle upper panel). The NWS forecasters issued a tornado warning immediately, based on this and other information. Even after the circulation in the storm weakened, very strong destructive straight-line winds were still observed in the area which produced major damage to the area (pink arrows in lower panels at 0240 and 0250 UTC). This case shows how valuable the CASA radar network and its low-level wind analysis products can be, even with a 10 minute delay in the availability of the products in 2009. The efficiency of the ARPS 3DVAR analysis program and its pre-processors has been greatly improved since, and each analysis can now be completed within 4 minutes of the observation time.

The total u-v wind vectors and composite reflectivity (colored) at model surface level from 0200 UTC -0250 UTC 14 May, 2009 for the Anadarko, Oklahoma tornadic thunderstorm case.