The FLASH product is a suite of 3 different modeling products
They can be gathered from:

HowTo’s
Pull from https://mrms.ncep.noaa.gov/2D/FLASH/
class : SpatRaster
size : 3500, 7000, 1 (nrow, ncol, nlyr)
dimensions : X, Y (7000, 3500}
resolution : 0.009999999, 0.01 (x, y)
extent : -130, -60, 20, 55 (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat Coordinate System imported from GRIB file
source : MRMS_FLASH_CREST_MAXSTREAMFLOW.latest.grib2.gz
varname : FLASH_CREST_MAXSTREAMFLOW_0-SFC (FLASH QPE-CREST Streamflow [m^3/s])
name : FLASH_CREST_MAXSTREAMFLOW_0-SFC
unit : m^3/s