So, to start out, I live in tornado alley 
I haven’t received my Artemis Redboard Nano yet, but have started programming. My Arduino Pro Micro just doesn’t have enough to do all that I want to do with the Si4707. So, I have started correcting compiling errors with the new board, and I am kinda running into a roadblock. So, I imagine the whole PROGMEM is unnecessary, so I fixed that. Next issue pertains to being able to disable the interrupts, and I have tried finding docs on the Artemis, but they seem to be greatly lacking. anyone know the equivalent register to the Atmel SREG register? Also have issues with the ADCSRA register. Probably will run into having to adjust the timer code as well. Lastly, is there a direct GPIO port on Artemis, like the Atmel PORTB? Thanks!
PROGMEM is not necessary in the sense that there is plenty of RAM for data - we don’t have to store any in FLASH (unlike pro micro 
) If you do end up wanting to store data in FLASH (for power-off retention) then you have access to the EEPROM library.
I’m unfamiliar with the SREG. But you are asking about disabling interrupts? What sort of interrupts? The Apollo3 (the uC inside the Artemis module) is based on an ARM Cortex-M4 core and so much of the interrupt functionality is common to many other Cortex-M4s.
More documentation about the Apollo3 exists here:
Btw tornado chasing sounds like an interesting hobby!