How do I decode FAA SNOWTAMs?
So, a SNOWTAM actually has a different format, and your example is just a standard NOTAM in ICAO format.

12/057 NOTAMN  Q) ZBW/QMRXX/IV/NBO/A/000/999/4221N07100W005     
  A) KBOS  B) 1912310152  C) 2001010152      
  E) 09 FICON 5/5/5 100 PCT WET OBS AT 1912310152.


This decodes into the following:

Series and number:        12/057
Nature of the NOTAM:      New (N in the NOTAMN)

Q) Qualifier line:  
   FIR:                   Boston FIR (ZBW)
   NOTAM Code:            Starts with Q and the following four letters:
                          Subject: Runway (MR)  
                          Condition: Not Specified / Plain Language (XX)  
   Traffic:               NOTAM issued for IFR (I) flights and VFR flights (V)  
   Purpose:               NOTAM selected for immediate attention of flight crew members (N), 
                          for PIB entry (B), and concerning flight operations (O)  
   Scope:                 Aerodrome (A)  
   Limits:                FL 000 to FL 999 (000/999)  
   Geographical location: 42°21' N 071° 100' W (4221N07100W)
                          Operation radius of the NOTAM: 5 NM (005)  

A) Aerodrome:             Boston Logan (KBOS)  
B) From:                  01:52 UTC 31 December 2019 (191231 0152)  
C) Until:                 01:52 UTC 01 January 2020 (200101 0152)  
E) Text of the NOTAM:     Runway 09 Field Condition
                          Braking action 5/5/5 (good for each third of the runway), 
                          Runway is 100% wet
                          Observed at 0152 UTC on 31 December 2019


We could dig into the ICAO documents to find the official guidance, but different countries implement it differently sometimes anyway.  Here's a good document that I found which breaks down the different codes.