This might give you an idea:
rasterlist = [
"Week_1_Sum1981_10_Crawford.tif",
"Week_1_Sum1982_10_Crawford.tif",
"Week_1_Sum2016_10_Crawford.tif",
"Week_2_Sum1981_10_Crawford.tif",
"Week_2_Sum2016_10_Crawford.tif",
"Week_5_Sum2016_10_Crawford.tif"
]
for year in range(1982, 1982+1):
for month in range(10, 10+1):
for week in range(1,1+1):
raster = "Week_{}_Sum{}_{}_Crawford.tif".format(week,year,month)
if raster in rasterlist:
print "Found: {}".format(raster)
If you want to put all the tif files in a directory into a list you could use something like:
import os, glob
rasterDir = r'C:\Path\To\Rasters'
rasterlist = list(os.path.basename(x) for x in glob.glob(rasterDir + r'\*.tif'))
print rasterlist
Hope this helps.