Here's a list of resources I use to make my maps. If you see anything in my maps that I don't have listed here, shoot me an email and ask where I got it from. If it's freely available, I'll be happy to send along a link or point you in the right direction.
Some of the files (like the WPC's percentile forecasts) are listed in .grb format, which requires the National Weather Service's tkdegrib program to convert into a usable file. The link is at the very bottom of this page.
SEVERE WEATHER
SPC OUTLOOKS
Current Watches (IEM)
Current Warning Polygons (NWS)
SBW Polygon Archive (IEM)
SPC Storm Report Archive (IEM)
SATELLITE IMAGERY
GOES WEST Directory (NOAA)
(GIS products for GOES East are no longer publicly available after GOES-16 took over operational duties in December 2017. If you ever hear of publicly-available GIS data for the new satellite data, please shoot me an email and let me know.)
PRECIPITATION
HURRICANES
NHC GIS DirectoryLatest Graphical Tropical Weather Outlook
Wind Speed Probabilities (Polygons)
Wind Speed Probabilities (Points)
Current SSTs
Historical Hurricane Tracks (WMO)