The PIs intend to test their prediction abilities on a given day the location and timing of ionospheric irregularities in the high latitude F region. Much of the high latitude F-region weather is cause by small scale (irregularities) and large scale (polar cap patches, polar cap arcs, boundary blobs, subauroral blobs, auroral blobs, auroral ionospheric cavities) electron density structures. There is an intimate cause and effect relationship between these small and large scale irregularities. The PIs will use the Global Theoretical Ionospheric Model (GTIM) to determine the requirements for accurately forecasting patches and blobs, and, in turn, using expressions for instability growth rates, forecast the appearance of electron density irregularities. In sum, this three-year project will: (1) test current understanding of large scale F-region structures and their ability to produce small scale irregularities, (2) confirm the role of two instability processes in generating small scale irregularities, (3) test current capability to specify and forecast conditions in the high latitudes that impact satellite communications, (4) help establish what processes need to be included in any physics-based ionospheric weather model, and (5) establish the level of detail required in the high-latitude electric field in order to specify and forecast ionospheric weather.