Skip to content

Warning Lifecycle & Updates

Jump to bottom
full-bars edited this page May 3, 2026 · 1 revision

Warning Lifecycle & Updates 🌪️

SPCBot provides more than just initial alerts; it tracks the entire lifecycle of NWS warnings in real time, from issuance to cancellation.

🔬 VTEC Parsing

The bot's intelligence is rooted in VTEC (Valid Time Event Code) parsing. Every NWS product contains a VTEC string (e.g., /O.NEW.KOUN.TO.W.0042.../) that identifies:

  • Action: NEW (Issuance), CON (Continue), EXT (Extend), CAN (Cancel), EXP (Expire).
  • Office: Issuing WFO (e.g., KOUN).
  • Phenomenon & Significance: TO.W (Tornado Warning), SV.W (Severe Thunderstorm Warning).
  • ETN: Event Tracking Number—a unique, stable identifier for that specific storm's lifecycle.

🚀 The Low-Latency Pipeline

To ensure sub-10 second delivery, SPCBot uses a dual-path pipeline:

  1. Fast-Trigger (NWWS-OI/IEMBot): As soon as a raw text product is received, the bot parses the VTEC and posts a "NEW" issuance immediately.
  2. Polling Fallback (NWS API): The bot polls the NWS API every 30 seconds to catch any products missed by the push feeds and to rehydrate state after a restart.

🔄 Real-Time Lifecycle Updates

Unlike basic bots, SPCBot updates its posts as the storm evolves:

  • Continuing Updates (CON): When a warning is continued, the bot posts a concise update note.
  • County-Level Precision: The bot calculates which counties have been cancelled and which are continuing in each update (e.g., (cancels Clarke, continues Jones [MS])).
  • Severity Tags: Automatically detects and highlights PDS (Particularly Dangerous Situation), Tornado Emergencies, and Destructive Severe Thunderstorm tags.

⏹️ Graceful Cancellations

When a warning expires or is cancelled:

  • The bot posts a dedicated Cancellation Notice.
  • The notice includes a relative timestamp (e.g., (cancelled 2 minutes ago)).
  • The original issuance post remains as a historical record, but the new notice signals the end of the threat to users.

🗺️ Automated Mapping

Every warning post includes an IEM Autoplot 208 map showing the warning polygon, affected counties, and a storm-relative radar snapshot.

Clone this wiki locally