Link: https://mesonet.agron.iastate.edu/request/gis/watchwarn.phtml
For various convoluted reasons, the IEM maintains a downloadable archive of many National Weather Service Watch, Warning, and Advisories. This archive is very unique to the known public Internet with no known freely available alternatives, which I suppose is a prideful statement, but also a scary one as there is no known "answer key" to compare IEM processing with. Anyway, this archive intends to be a complete archive of NWS products implementing VTEC (Valid Time Event Code), which was another in the line of convoluted things attempting to make parsing NWS ASCII text products sane. The VTEC implementation started in 2005, but many moons ago the IEM did some special processing attempting to create VTEC events prior to 2005 for a limited set of warning types.
Enough backstory, this news item denotes an addition of fake-VTEC warning types covering certain marine products in Alaska. Again with the convoluted term, but for such reasons Alaska forecast offices do not implement VTEC for things like Gale Warnings and Small Craft Advisories. Instead, they have a zone based forecast product that implements these events as headlines within the forecast. An example product is CWFNSB with an ASCII text like so:
PKZ811-210330- Cape Thompson to Cape Beaufort out to 15 NM- 402 AM AKST Wed Nov 20 2024 ...STORM WARNING IN EFFECT THROUGH LATE THIS MORNING... ...HEAVY FREEZING SPRAY WARNING IN EFFECT FROM LATE THIS AFTERNOON THROUGH EARLY THURSDAY MORNING...
So in this case, we have a Storm Warning (
SR.W) and a Heavy Freezing Spray Warning (UP.W) for Marine zone PKZ811.
The IEM now has processing that attempts to create these "fake-VTEC" events in realtime and has back-filled this processing to the start of 2005. FAQ Item 7 for the VTEC dataset has a bit more color on this. The biggest caveat is that the temporal handling of these events is very crude. Absent of any NWS documentation on how these events are to be timed, the least painful coding life choices were made with the pyWWA ingestor written.
As always, I am happy to field any questions about this and hope the community finds this addition useful.