I’m not seeing the 151 error. Those links open fine for me directly in a Chrome browser. What WD is putting in the metar folder is a .taf file (KSEA.taf):
Contents:
KSEA 171747Z 1718/1824 19003KT P6SM BKN015 OVC020 FM171900 VRB03KT P6SM BKN020 OVC060 FM172100 34006KT P6SM SCT025 BKN040 FM180000 35003KT P6SM SCT025 BKN040 FM180700 11004KT P6SM SCT015 BKN030 FM181200 11004KT P6SM SCT010 BKN025 FM182100 23004KT P6SM SCT025 OVC060