From a stream of notices to one ledger of outages: how much capacity is out, where, and for how long.
Interstate pipelines publish critical notices on their electronic bulletin boards when a compressor, segment or meter station cannot move its normal volume: a force majeure after a leak, a planned station overhaul, a hurricane evacuation. Each outage usually produces several postings — the declaration, a string of updates, an extension, and finally the lift. A calendar that draws one bar per notice would show when the notices were posted, not how long the capacity was actually out.
The Capacity Offline calendar draws one bar per event. Enercast links each notice to the facility it concerns, rolls the stated start and end dates forward as updates and extensions post, and closes the bar on the day the pipeline declares the constraint lifted. The result is an in-effect ledger: for any gas day you can read how many Bcf/d of pipeline capacity were out, on which systems, and whether the loss was planned.
Stated means the pipeline posted the reduction itself ("eastbound capacity reduced by 504 MMcf/d"). Derived means Enercast subtracted the posted new ceiling from the posted prior capacity or from the location's recent operating capacity. Inferred marks older notices classified by rule rather than by reading. ~Est. is an observed figure: the drop in the location's posted operating capacity after the notice, used only when the notice gives no volume. Ceiling-only notices ("capacity through Station 50 is limited to 2.27 Bcf/d") are shown with the ceiling and excluded from every total, because a ceiling is not a loss. Only stated and derived reductions are added into the Bcf/d total; estimates are shown alongside it, labeled.
Capacity out is not one number for a gas trader. A constraint that strands supply — a gathering lateral, a processing plant, a Canadian import point — removes gas from the market and reads bullish for Henry Hub. A constraint that cuts demand — feedgas to an LNG export terminal, a citygate, a power plant lateral — keeps gas at home and reads bearish. Most outages sit between the two on a mainline compressor; those are tagged by the scored Henry Hub direction, or basis-only when the effect is regional.
Several times a day, from the latest scoring cycle. The ledger is rebuilt from scratch each time, so a lift or extension changes the bar rather than adding a new one.
Either the pipeline posted a ceiling and not a reduction, or the notice gives no volume at all. Where posted operating capacity at the location dropped after the notice, an observed estimate is shown and labeled as such.
The notice had no end date and the pipeline has stopped re-listing it. It may have ended without a posted lift. Stale events are shown dashed and are not in the total.
No. “Due back” and “Starts” list the pipelines’ own posted dates. The next morning the ledger checks whether the capacity actually returned, and an outage whose end date passes without a return notice is shown as dropped off rather than counted as back.
At the compressor station, processing plant or LNG terminal named in the notice when Enercast has its location (from HIFLD public infrastructure data, matched by hand). When the notice names a stretch of pipe or a location we have not mapped yet, the marker sits on that pipeline’s line and its popup says “facility not located”. A few LNG feed pipelines with no public route data are drawn as dashed, schematic lines.
More questions? See the general FAQ (plans, timing, access) or email support@enercast.com.
More guides: How Enercast works · Critical notices · Supply & demand · Getting alerts · Glossary