Frequently Asked Questions about

Q: How are WPC's Mesoscale Precipitation Discussions different from SPC's mesoscale discussions and the NESDIS SPENES message? Both of these existing products already address the short-term potential for heavy rainfall.

The WPC Mesoscale Precipitation Discussions (MPD) and accompanying graphics are modeled after SPC's Mesoscale Discussions with a particular emphasis on the potential for flash flooding. There is a proposal to transfer the responsibility for heavy rainfall discussions from SPC to WPC by the end of the year, although SPC will retain responsibility for discussions related to heavy snowfall. The NESDIS SPENES messages provide quantitative satellite-derived precipitation estimates and satellite trend guidance to the National Weather Service. WPC's MPDs are designed to complement these messages by providing a forecast of the evolution of the heavy rainfall and associated flash flood threat. WPC is co-located with NESDIS and both agencies coordinate directly when discussions are being issued for the same area.

Q: What is the AWIPS PIL?

Since the Mesoscale Precipitation Discussions (MPDs) are currently only a prototype product, they are not available in AWIPS. The MPDs should be available in AWIPS once they officially become experimental in December. In the meantime, the discussions will be available through this website (, and WPC will send a 12Planet message to the affected offices using the ID hpc_Metwatch.