Help & glossary

The verdict stamp

The big stamp at the top of the page is the overall jump call for your license tier (set in Settings → My license). Four states:

• LIKELY — every criterion in scope passes. Conditions favor a jump.
• UNLIKELY — conditions are marginal or over a hard cap. Jumps are possible but the manifest may hold. The stamp color tells you how far off it is: amber is borderline, while red means a hard cap is breached (wind over your tier's cap, ceiling below exit, active precip) — don't expect jumps.
• UNVERIFIED — required data is missing right now (e.g. cloud or precip didn't load). The app refuses to call it.

Per-tier verdicts (Student → Tandem) appear below the stamp so an A-license holder can still see whether a student would be on hold under the same conditions.

Surface wind

17 kt (the big number)

Steady wind speed in knots. From GFS 1000 mb (~365 ft AGL) — the same altitude winds-aloft tables report as “surface.”

WNW · 290°

Direction the wind is coming from, meteorological convention. WNW = west-northwest.

Gusting 23 kt

Peak gust observed/forecast in the current window. Hidden when gust ≤ steady.

Gust spread 6 / 9 kt cap

Gust minus steady (here: 23 − 17 = 6 kt). USPA's de-facto cap for sport jumping is ~9 kt of spread. Exceeding the cap grounds the jump even if steady is well under the speed cap.

6-hour gust strip

Six bars showing the forecast gust spread (gust − steady) over the next six hours. Each bar is colored against the 9 kt cap: short = calm, full = at-the-cap. Useful when conditions are marginal now but the trend matters — “is the spread climbing or fading?”

Wind column (aloft)

A vertical stack of rows from exit altitude down to the surface, showing wind speed and direction at each pressure level. From GFS winds-aloft products at 1000 / 925 / 850 / 700 / 500 / 300 / 250 mb pressure levels — what NOAA calls a winds-aloft forecast (FB) and what jumpers and pilots have been reading for fifty years.

Pull alt 4,000 ft (slider)

Drag to shade the rows from your pull altitude down to the surface — this is the “canopy zone.” The verdict looks for shear (wind direction or speed changing sharply across this band).

Arrow on each row

Points the direction the wind is going (downwind), not where it's coming from. Speed in knots in the label.

Cloud cover

5,000 ft ceiling

The altitude of the lowest broken or overcast layer. Per FAR 105 you need 1,000 ft clearance above the highest exit-altitude cloud, so a 5,000 ft ceiling forces a low pass or grounds high exits.

Sky clear / Open above

Headlines when no layer qualifies as a ceiling. Sky clear means no clouds detected at all; Open above means there are clouds but only Few/Scattered — they don't gate exits.

81% cloud cover

Total sky coverage — the fraction of the dome above you that has clouds at anyaltitude, blended across all layers. 0% = clear, 100% = overcast everywhere. This is the single “how cloudy is it?” summary number.

Scattered · 4/8 and friends

Per-layer coverage using the FAA octa system. A METAR observer divides the sky into 8 imaginary pie slices and reports how many are covered:

• SKC · 0/8 — Sky clear
• Few · 1–2/8 — Few clouds
• Scattered · 3–4/8 — Scattered (SCT)
• Broken · 5–7/8 — Broken (BKN)
• Overcast · 8/8 — Overcast (OVC)

Aviation convention: the ceiling is the lowest BKN or OVC layer. Few/Scattered layers don't count as a ceiling — you can legally exit above them.

(ceiling) badge

Marks which layer is the operational ceiling. Layers above it are listed for context but don't drive the grounding decision.

Precipitation

Light rain likely in 45 min

Next forecast precip event over the DZ, with onset rounded to the nearest 5 min (the radar forecast cadence). “Likely” means probability ≥ 50%.

No rain in next 6 hours

Radar shows nothing reaching the DZ across the forecast window. Safe on this axis.

52% chance in that hour

Probability of precipitation (PoP) during the hour the onset falls in. Derived from radar reflectivity (dBZ): 12 dBZ → ~50%, 25 → 70%, 40 → 85%, 50+ → 95%.

Intensity (light / moderate / heavy)

Classified from peak dBZ over the next hour. “Light” ~ drizzle (12–25 dBZ), “moderate” ~ steady rain (25–40 dBZ), “heavy” ~ thunder/downpour (40+ dBZ).

Source: TWC radarFcstV3 — 5-minute steps out to 7 hours. We sample the single radar pixel at the DZ coordinates.

Projected start

If conditions are UNLIKELY right now, this card walks the hourly forecast looking for the first hour where every criterion passes for your license tier. Three outcomes:

• First likely at 14:00 — that's when the manifest will likely re-open.
• Possible after 11:00 — marginal; depends on the DZSO call.
• Unlikely through forecast — no viable window in the next 6 hours; pack up.

What this app does not tell you

• Whether the jump aircraft is mechanical or the pilot is on-site.
• Whether the DZ is open for tandems, students, or experienced today.
• Whether the DZ will fly a load — tandems on hold can mean no fun-jumper load.
• TFRs, NOTAMs, or airspace closures (planned for v2).
• Night-jump eligibility or astronomical twilight (planned).

The manifest desk is the source of truth. This site is a fast pre-check before you start the drive.