Based on the operational importance of short-term watches and warnings associated with land-falling Pacific winter storms, and on the potential to improve on these through enhanced coastal and offshore observations, two experiments have been conducted recently on the U.S. West Coast. The California Land-falling Jets experiment (CALJET) of 1997/98 and the Pacific Land-falling Jets experiment (PACJET) of 2001 used a variety of approaches to explore this problem. Efforts focused on quantitative precipitation forecasting and optimal observing system assessments, both high priorities of the U.S. Weather Research Program (USWRP). The core philosophy was to combine physical process studies associated with coastal weather, with observing systems tests and forecasting applications development.

This presentation will summarize some of the key lessons learned to date regarding the capabilities and limitations of existing coastal and offshore observations. It will also describe how the introduction of experimental observations from wind profilers, GPS integrated precipitable water vapor measurements, aircraft (in situ, dropsonde and airborne radar), and enhanced GOES satellite winds can fill key gaps in the current operational observing system. Examples will include comparisons of surface observations, NEXRAD radars and coastal wind profilers in terms of monitoring the low-level jet and coastal blocking in land-falling winter storms. The potential value of offshore airborne radar observations from NOAA's P-3 aircraft in filling gaps in coastal NEXRAD coverage will also be shown, as will the impact on a coastal storm forecast of dropsondes released roughly 100-1500 km offshore by NOAA's G-IV jet.