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In spring of 2026 Powderguide partnered up with endurance athlete Tobias Renggli, who, together with our friend and mountain goat Heli Hoffmann and polar scientist Laetitia Lam, intended to scale, as the first of many mountains in America, Denali in Alaska, the tallest of the USA. So I became their expedition’s meteorologist. I refined my primary tool, the PowderGram, feeding it with
- the global ICON forecast, for an estimate of the mid-range (7.5 day) weather conditions, and with
- high-resolution forecasts for the mountains of Alaska, WRF-HRRR, run by NCEP, for the most precise short-term (48h) forecast.
The advantages of this approach are
- I know what is done
- all information in one graph
- precise localization
- confronting valley, mountain and circumference averages
- PowderGrams are updated daily on the PG-Map
- forecasts in text or PowderGrams as images can be sent via Garmin messenger.
Denali, 6190m, on 15/05/2026
My team summitted in the afternoon of the 15th of June in 2026, as the first of the season. The following were my forecasts:
[Forecast as of 14/05/2026] [16 AKDT]
Tomorrow, 15/05 | Camp IV - CampV Conditions:
Clouds passing by in calm winds!
☀️ SUN: little chances for sunshine, but not none.
👁️ VISIBILITY: Limited and variable visibility, no long-lasting whiteout forecasted.
💨 WIND: Winds turn northerly. They are calm with speeds less than 20 km/h and little gustiness.
☁️ CLOUDS: Intermittent low and mid-level cloudiness.
🌧️ PRECIP: Light snowfalls forecasted around 3PM. Accumulations less than 5 cm.
🌡️ TEMPS: Temperatures at Camp IV [4300 m.a.s.l] around -20°C, wind chill temp. around -25°C, at CampV [5225 m.a.s.l] around -30°C, wind chill temperature around -40°C. Pressure rising again, advection of slightly cooler and drier air, but wind chill effect is weak.
The day after tomorrow, 16/05 | CampV - Denali Summit Conditions:
Sunshine in significant winds!
☀️ SUN: high chances for sunshine from 9 AM on.
👁️ VISIBILITY: Great visibility.
💨 WIND: Winds turn back south-south-westerly. They speed up to 30-40 km/h, with gusts around 50 km/h.
☁️ CLOUDS: Little cloudiness forecasted.
🌧️ PRECIP: No precipitation forecasted.
🌡️ TEMPS: Temperatures at CampV [5225 m.a.s.l] around -35°C, wind chill effect is significant, and can be as low as -55°C. On the summit [6190 m.a.s.l.], temperatures around -45°C, wind chill temperatures can go below -60°C.
for which I used mainly used these two PowderGrams, one using WRF-HRRR-AK and one ICON, for valley location Camp IV and mountain Denali summit: <
and finally I advised.
Summit Push Situation:
15/05: I see this day due to calm winds and despite limited visibility as favorable for getting back up to Camp V.
16/05: I must warn in regards of the winds, and the wind chill temperatures. Else, I see excellent visibility until late in the day, and obviously no precipitation. Only by midnight cloudiness is forecasted to return.
17/05: Winds remain at moderate speeds, gustiness increasing, maybe to beyond -75 km/h. Unmounting Camp V can pose a challenge. But eventually you can judge on 16/05 yourself, the windiness is similar, only gustier on 17/05. No significant precipitation forecasted. Mixed visbility, no whiteout to be expected, and even sunshine possible.
18/05: Weather situation not changing much. Gustiness calming down.
19-21/05: No storm to be expected, but precipitation possible. A retreat to Base Camp nevertheless should be possible. Note that I do not see a favorable and sunny weather window here.
21/05 seems sunny, but this is long time ahead.
*eventually the team decided to go fast and avoid the winds forecasted. They took their chance, favoring calm winds above mixed cloudiness, and summited. During their ascent I kept on updating them, using the WRF-HRRR-AK, which is refreshed 3-hourly, and assuring them in regards of the threat that were the winds arriving. *
Bolivian First Descents by Schulz et al.
Alongside the North-American adventures, a team around Malte Schulz opted for steep ski descents in the Bolivian Andes, in late April / early May 2026. Within not even 2 weeks the made quite likely the first ski / snowboard descents of
- Ancohuma, Bolivia (6427 m) — April 2026
- Parinacota, Bolivia (6380 m) — May 2026
- Chearoco, Bolivia (6127 m) — May 2026
Weather and snow conditions had been favorable and I am proud to say that my forecasts were certainly supportive.
Summary of Mountains summited:
- Ancohuma, Bolivia (6427 m) — April 2026
- Parinacota, Bolivia (6380 m) — May 2026
- Chearoco, Bolivia (6127 m) — May 2026
- Denali, USA (6190 m) — May 2026