Plain English Meaning
A very short forecast — covering the next two hours — that tells you what the weather is doing right now and what it is likely to do in the immediate future.
Full Definition
A short-range weather forecast describing current conditions and their expected evolution over the next two hours, based on real-time observations such as radar, satellite, surface reports, and pilot reports. In the context of Center Weather Advisories (CWAs), a nowcast addresses hazardous weather affecting an Air Route Traffic Control Center's airspace within that two-hour window.
Context Anchor
Seen in Center Weather Advisories, where fast-changing weather may affect in the near future.