The rugged and topographically-diverse terrain of Alaska, in conjunction with the data-sparse regions surrounding this area, make short-range mesoscale forecasting extremely challenging. The substantial lack of observations in this region has long plagued the success of numerical weather prediction in Alaska. Additionally, the complex mountainous terrain and land-sea interface warrant specific tuning of model physics and parameterization to properly utilize what few observations do exist.

The Alaska-based airline PenAir began equipping a fleet of 8 Saab 340s with Tropospheric Airborne Meteorological Data Reporting (TAMDAR) sensors in late June 2007. The sensor measures humidity, pressure, temperature, winds aloft, icing, and turbulence, along with the corresponding location, time, and altitude from built-in GPS. These observations are transmitted in real-time to a ground-based network operations center via a global satellite network.

Data-denial studies over this region are currently being performed by employing a version of the NCAR Advanced Research WRF (ARW). Parallel 48 to 72-h experimental (control) simulations include (withhold) the PenAir TAMDAR data. Case-specific and time-averaged forecast skill statistics, verified against other observing platforms (e.g., RAOBs, ASOS, etc.), are compiled and analyzed for various domains and model configurations in, and downstream of, Alaska.

The objectives of this study are to (i) quantify any impacts that TAMDAR data may have on high-resolution short-range mesoscale forecasts over, and downstream, of Alaska, as well as (ii) monitor the accuracy, tuning, and health of the PenAir-based TAMDAR observing system.

The PenAir equipage is still being refined; however, initial forecasts and simulations using only a partial data set show very promising results. The ongoing studies and more complete results will be presented at the time of the conference.