It's a really dumb system I made, I've got 5 markers each one block away from eachother in the direction I'm facing, then if the block ontop of one of the markers is powdersnow, then it runs the command.

In other words:
execute as @e at @s run scoreboard players add @s spawntimer 1
execute as @a at @s if score @s spawntimer matches 1 run tag @s add blockdetector
execute as @a at @s if score @s spawntimer matches 1 run summon marker ^1 ^ ^ {Tags:["blockdetector","bd1"]}
execute as @a at @s if score @s spawntimer matches 1 run summon marker ^2 ^ ^ {Tags:["blockdetector","bd2"]}
execute as @a at @s if score @s spawntimer matches 1 run summon marker ^3 ^ ^ {Tags:["blockdetector","bd3"]}
execute as @a at @s if score @s spawntimer matches 1 run summon marker ^4 ^ ^ {Tags:["blockdetector","bd4"]}
execute as @a at @s if score @s spawntimer matches 1 run summon marker ^5 ^ ^ {Tags:["blockdetector","bd5"]}
execute as @e[​tag=bd1] at @p anchored eyes run tp @s ^ ^1 ^1
execute as @e[​tag=bd2] at @p anchored eyes run tp @s ^ ^1 ^2
execute as @e[​tag=bd3] at @p anchored eyes run tp @s ^ ^1 ^3
execute as @e[​tag=bd4] at @p anchored eyes run tp @s ^ ^ ^4
execute as @e[​tag=bd4] at @p anchored eyes run tp @s ^ ^ ^5

execute as @e[​tag=blockdetector] at @s if dimension the_nether if block ~ ~ ~ powder_snow unless entity @e[​tag=snowbomb,distance=..0.9] run summon marker ~ ~ ~ {Tags:[​snowbomb]}