Le Grand Ratz
📍 Rhone-Alpes , Departement de l'Isere · Nearest city: La Buisse (1 km)
54 XC score / 100 · takeoff at 802 m · 📍 View on map
Coordinates and external links
45.32930, 5.63590Forecast next days
Updated: 2026-04-19 16:15 UTC · Source: Open-Meteo · Thermal window 10:00–18:00 local time
Día muy favorable para XC, base de cúmulos ~991 m, viento 13 km/h.
base ~991m · wind 13 km/hDía volable, condiciones decentes, base de cúmulos ~948 m, viento 13 km/h.
base ~948m · wind 13 km/hCondiciones marginales, base de cúmulos ~1091 m, viento 12 km/h.
base ~1091m · wind 12 km/hComposite flyability score (CAPE + LI + wind + precip + low clouds). Cross-check with local pilots before flying.
Detailed hourly weather
2026-04-20✅ Flyable · peak 65 at 14h
| 08 40 | 09 50 | 10 50 | 11 50 | 12 55 | 13 60 | 14 65 | 15 65 | 16 65 | 17 60 | 18 60 | 19 50 | 20 50 |
Peak 14h: CAPE 10 J/kg · LI 0.7 · BL top 1060 m · w* 0.0 m/s · cloud base 1964 m · 0°C at 2850 m · Pro score 60/100 · sun 36° over slope
2026-04-21⚠️ Marginal · peak 55 at 15h
- Día muy estable (CAPE<50, LI>2) — sin térmicas
| 08 30 | 09 30 | 10 30 | 11 35 | 12 35 | 13 35 | 14 35 | 15 55 | 16 55 | 17 55 | 18 55 | 19 55 | 20 35 |
Peak 15h: CAPE 0 J/kg · LI 3.9 · BL top 1060 m · w* 0.0 m/s · cloud base 1739 m · 0°C at 2770 m · Pro score 62/100 · sun 31° over slope
Hourly flyability (0–100). ⛈️ = storm risk · ☁️⚠️ = cloud suck · 🏔️ = active ridge lift. CAPE = convective energy, LI = stability, BL top = thermal ceiling, w* = estimated dry thermal velocity. Source: Open-Meteo (ECMWF/GFS/ICON blend model).
Estimated vertical profile (Sounding)
Reference time: 14:00 (peak of the day)
Surface T: 15.9°C · Td: 6.6°C
LCL (cloud base): 1162 m
BL top: 1060 m
0°C level: 2850 m
Approximate profile from surface variables + synoptic levels. Red lines = temperature, dashed blue = dew point. Orange bands = detected inversions.
Takeoff orientations
Green = good orientation · Yellow = possible · Gray = not suitable
Why this site has thermal potential
| Factor | Value | Interpretation |
|---|---|---|
| Hotspot density (5 km) | 7 | Medium |
| Avg thermal probability | 0.86 | Based on thousands of aggregated IGC flights |
| Solar orientation | 0.35 | Slope faces south in northern hemisphere |
| Own flight history | 0.00 | Thermals detected in platform IGC tracks |
Takeoff description
20 mn by foot from parking at Le Grand Ratz village, over La Placette pass, near Pommiers La Placette, north of Voreppe, 15 km NW of Grenoble Afternoon and evening take off. Caution with south wind, not detectable at take off ...
Nearby sites
Chalais (55) · La Grande Sure (56) · petit Montaud (44) · Charmant Som (47) · Montaud (42) · Charande-la moliere (50)