How to track Cushing crude stocks between EIA weekly reports
Cushing sits at the middle of every WTI conversation, and the only official count of what's in the ground there comes out once a week. The EIA's Weekly Petroleum Status Report posts Wednesday at 10:30 a.m. Eastern, covers the week that ended the previous Friday, and then goes quiet for seven days. A lot can move at the hub in that window. A trader working a Cushing differential or an analyst writing a storage note needs something to lean on in between.
What the weekly report tells you, and when it stops telling you anything
The EIA number is a snapshot, not a feed. By the time it prints Wednesday morning, it's already describing Friday's world, five days gone. Between one release and the next, nobody outside the terminal operators has a confirmed figure for the hub.
The American Petroleum Institute puts out its own survey Tuesday afternoon, and traders use it as a rough pointer on direction. It's a market-wide estimate built from a survey of a subset of operators, covering overall crude stocks rather than breaking out Cushing specifically. Both numbers are useful. Neither one covers the days around them.
This is the storage report lag that shows up in every Cushing conversation eventually: real builds and draws happen daily as pipelines nominate barrels in and refiners or exporters pull them out, but the public record updates on a weekly clock. A big draw on Monday and a partial rebuild by Thursday can net out to something the following week's report barely shows, even though the week had real volatility in it.
What people do to fill the gap
Most of the workarounds traders use are proxies, and it helps to know what each one is measuring.
Pipeline nomination and flow data gets you directional information on what's scheduled to move in and out of the hub, but nominations aren't always fully run, and flow data alone doesn't tell you how full a given tank farm is sitting today. Cushing's working storage capacity is public, so some desks back into a rough utilization rate using the last confirmed EIA number plus whatever flow signal they trust, then adjust it by feel as the week goes on. That's a model, not an observation, and the error compounds the further you get from the last printed figure.
Rail and truck movement at the margins barely matters for Cushing specifically since it's almost entirely pipeline-fed, so that's less useful here than it might be for other hubs.
What's missing from all of these is a physical read of the tanks themselves, something that answers "how full is Cushing right now" instead of "how full was Cushing five days ago, adjusted for what we think happened since."
A physical read instead of a modeled one
Floating-roof tanks, which make up most of the storage capacity at Cushing, sit lower in the tank as the oil level drops. That roof position casts a shadow, and the shadow's size and angle change in a way that tracks the fill level inside, tank by tank, independent of whatever the operator chooses to disclose. It's the same physical fact the EIA's own survey methodology ultimately rests on, just without waiting on the Wednesday release to see it.
Oil Tank Fill reads that shadow geometry across a defined storage area daily and turns it into a per-tank fill estimate, so a desk gets a current read on the hub between EIA prints instead of carrying a stale number forward and hoping the week was quiet. It doesn't replace the weekly report, it fills the six days around it with an observation of the tanks rather than an inference from flows and nominations.
The short version
The EIA report is accurate for the Friday it describes and silent for the week after. API gives a Tuesday-afternoon directional pointer that isn't hub-specific. Pipeline flow data tells you what's scheduled to move, which is a different thing from what's sitting in the tank right now. If you want to know where Cushing actually stands on a Monday or a Thursday, you need a current look at the tanks themselves instead of last week's paperwork.
If a mid-week Cushing read would change how you're trading the WTI spread or writing the storage section of your note, that's the gap this is built to close.