I'm put the contents of the tilemill project onto s3 for you:
http://mapbox-raster.s3.amazonaws.com/tilemill-debug/forecastio-project/layers/{high,med,low}.tif
http://mapbox-raster.s3.amazonaws.com/tilemill-debug/forecastio-project/project.mml
http://mapbox-raster.s3.amazonaws.com/tilemill-debug/forecastio-project/style.mss
The tiffs in question (high.tif, low.tif, and med.tif) were originally tiffs in a parent directory named low-blurred-geo.tif, med-blurred-geo.tif, and high-blurred-geo.tif.