How we read flying conditions

We don’t trust one forecast

For the exact launch coordinates we pull five independent weather models, then cross-check them against two official products — running our model blend against a separate, authoritative forecast so no single model can quietly steer the call wrong:

• HRRRUS 3km high-res (≤2 days)
• ECMWFbest medium-range
• GFSUS global
• ICONGerman global
• GEMCanadian global
• NWSUS official point forecast — independent cross-check
• TAFnearest airport’s aviation forecast (~24–30h) — human-refined

The headline follows the best model for the range — HRRR up close, ECMWF further out. How tightly all of them agree sets the confidence badge: High means ≥80% land on the same call with the wind speeds within 6 mph and directions within 45°; Medium is ≥60% agreement; anything noisier is flagged Low. One straight answer instead of you opening six tabs.

Direction first — everything else is moot if it’s the wrong way

Every launch has an ideal wind-direction arc and a marginal (cross) arc. Wind blowing outside both means cross, tail or rotor on launch, so it caps the call at Not flyable for every wing no matter how gentle it is.

Speed, gusts and thermals

After we check off wind direction, we score the air against ideal launch conditions:

• Base wind — the sweet spot is 6–10 mph. Under 4 mph it’s usually a sledder, not soarable; the default upper limit is 12 mph base / 15 mph gust (curated sites tune this).
• Gustiness — we penalise the gust spread (peak minus base) once it tops 7 mph, and harder as gusts approach the ceiling. High gusts usually read as borderline (caution).
• Thermals & cloudbase — read from CAPE and the temp/dewpoint spread: Light < 100, workable < 500, Strong < 1200, and ≥ 2000 J/kg is overdevelopment, which caps the day at caution or worse. A cloudbase under 2,500 ft AGL is flagged as limited working height.

An ideal launch is when the wind blows straight into the launch — inside the site’s direction window — at a steady, moderate speed: strong enough to fly, comfortably under the site’s limit, with gusts staying close to the steady wind rather than surging.

Predicting winds aloft & ridge height

We compare ridge-height wind (~80 m) with the surface read. If it’s over the limit aloft and clearly stronger than the surface (a gradient over 7 mph), an otherwise-flyable day is capped at caution — launch will feel stronger than the valley suggests. A direction shift of 30°+ with height flags shear. Finally, every call is gated to real daylight (sunrise to sunset); after dark is not considered flyable.

Temporary Flight Restrictions

For every launch we check the FAA’s live TFR feed and test whether any active restriction’s footprint actually covers the site. When one overlaps, the site page shows a warning with the restriction’s details. For safety we only ever add a warning — an FAA outage or a restriction filed just over a state line can slip through — so we never tell you a site is guaranteed clear. Always verify TFRs and NOTAMs on tfr.faa.gov before you fly.