The IEM has a database archive of SPC MCDs since 2003. The download offered here does not contain the MCD text discussion, but the polygon geometry along with some metadata. The backend database that services this download updates in realtime, so the data should be as current as your download.

Backend documentation exists for those wishing to script against this service.

Related: NWS Misc Polygons   NWS VTEC Watch Warning Advisory   SPC/WPC Outlooks   SPC Watch Polygons   WPC Precip Discussions

Time Interval for MCD *Issuance* (UTC)
YearMonthDay HourMinute
Start:
End:

Shapefile DBF schema:

Field 0: Type=C/String, Title=`ISSUE', UTC Issuance Timestamp YYYYmmddHHMM
Field 1: Type=C/String, Title=`EXPIRE', UTC MCD Expiration Timestamp
Field 2: Type=C/String, Title=`PROD_ID', IEM Product ID (see below)
Field 3: Type=N/Double, Title=`YEAR', YEAR of MCD
Field 4: Type=N/Double, Title=`NUM', SPC MCD Number
Field 5: Type=N/Double, Title=`CONFIDEN', SPC Watch issuance confidence
Field 6: Type=C/String, Title=`CONCERN', SPC MCD concerning heading

Archive / Usage Notes:

  1. The PROD_ID DBF field is a string the IEM uses to identify NWS Text products and can be used to call an IEM API to fetch the text of this product. https://mesonet.agron.iastate.edu/api/1/nwstext/{PROD_ID}
  2. The YEAR and NUM fields can be used to construct a stable URL into SPC's website like so: https://www.spc.noaa.gov/products/md/{year}/md{NUM:04i}.html