Live Radar Corridor

Radar is an observation of now, but you reach most of your route later. Four things have to hold before a quiet corridor is allowed to reduce anything:

• 1.The image is fresh. Reflectivity older than 20 minutes is not a nowcast, and nothing is reduced.
• 2.Radar actually saw most of your route. On a long leg the radar window only reaches the first stretch. If it has assessed less than 70% of your route points, it does not get to vouch for the rest — the models keep the call.
• 3.Storms that could move onto your path are counted. Each point is checked over a widening cone rather than a fixed circle, sized by how far a storm could travel before you get there. A cell 40 nm off-route with 90 minutes of lead time still blocks the reduction.
• 4.The stretch radar could not see still counts against you. Whatever the models forecast beyond the radar horizon sets a floor, so a quiet corridor next to a widespread forecast out ahead earns nothing.

A tall, intense cell also puts a brake on it: when radar shows a 50 dBZ core reaching roughly 30,000 ft, the reduction is limited even if coverage looks sparse, because a storm with that kind of updraft tends to grow and spawn new cells.

Model soundings answer “could storms fire?” Live radar answers “are they firing on my path right now?” Those can disagree — a loaded-gun atmosphere with a quiet corridor, or active cells where CAPE looked modest. Convective Watch now shows both so you don’t have to reconcile them yourself.

PlaneWX samples NOAA’s Multi-Radar/Multi-Sensor (MRMS) mosaic along a corridor around your route, then overlays that observational nowcast on the same segment bar you already use for model threat. When the two disagree and radar is the more credible of the pair, it can also soften the model’s thunderstorm deduction — see below.

Radar is a nowcast, not a day-3 forecast. PlaneWX attaches corridor radar when:

• Part of your flight falls inside roughly the next 2 hours (data age + time to each waypoint)
• The route has MRMS coverage (CONUS and nearby areas with mosaic data)
• Fresh mosaic data is available (typically refreshed every few minutes)

For departures farther out, you’ll still see model Convective Watch — radar simply isn’t meaningful that far ahead. On near-term flights, Visual Mode also leads with a Live radar (Windy) slide for situational awareness (that mosaic is separate from the MRMS corridor sample used in Convective Watch).

Bar colors follow the four intensity bands ATC uses when describing precipitation (Light / Moderate / Heavy / Extreme), with the green–yellow–red–pink look pilots expect from NEXRAD-style mosaics:

Coverage words on the badges (scattered / widespread) are about how much of the corridor is affected. Bar colors are about how strong the return is at each sample. A widespread light rain can stay green/yellow; a single extreme core can show pink on one segment. Scattered means about a quarter of the radar-covered, in-window samples are at 40 dBZ or heavier, or about 30% are at 30 dBZ — one core on the corridor is isolated, not coverage.

A low NOAA thunderstorm chance can also ease that same route line when radar did not see a cell. A cell on the corridor keeps at least an isolated deduction. See When the air has fuel but nothing is forecast to fire.

When radar softens a deduction, the line says so in place. Open Score Breakdown and look for wording appended to the thunderstorm line:

The original reason stays intact so you can see what the models said, and the bracket tells you what changed, why, how far either side of your course we looked, and how old the radar image was when we used it. If that age looks stale to you, weigh the line accordingly — the point of printing it is so you can second-guess us.

When the corridor is completely empty the deduction is removed rather than reduced, so there is no thunderstorm line left in the breakdown to carry a bracket. The explanation moves to the Sources panel on the Convective Watch card, under MRMS Radar:

Both readings are shown because they can disagree. The cap comes from the corridor you actually fly through; the reachability figure is the wider storm-motion cone, which asks whether a cell could catch you rather than whether one is on your course. A cone that reads scattered while the corridor is quiet is normal on a long leg, and it is the reason the Radar badge and the deduction can look like they are telling different stories.

It widens as you go. Near the aircraft radar samples a tight band of about ±10 NM around your path — what you’d actually fly through. Further down the route the band grows, because you don’t reach those points for another hour or more and a storm can travel a long way in that time. By the far end of a longer leg it can reach 40–60 NM either side.

That is deliberate. A cell sitting 40 NM off-route right now is genuinely irrelevant if you pass that point in ten minutes, and genuinely relevant if you pass it in ninety. The band is sized by how far convection could travel before you arrive, so “quiet” means nothing that could reach you has been found — not merely that the exact point is clear this instant.

It also never leaves gaps. On a long leg the sampled points can be 60–100 NM apart, so the band is always at least wide enough for neighbouring samples to touch. Storms well off-route can still appear on regional mosaics or inside SIGMET polygons without making your corridor “widespread” — that is expected.

• Convective Watch — dual badges, status strip, hybrid bar, and dBZ legend
• Weather Sources → Current — MRMS Radar card with corridor summary and data age
• Visual Mode (near-term departures) — Live radar (Windy) as the first slide
• Narrative / The Pattern — when radar is attached, the briefing text can reference the observational nowcast alongside CAPE and SIGMETs

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