The joint effort of a large Sherpa team has fixed the route to the summit of Everest in record time. However, the hundreds of climbers waiting for their turn after the long delay will have to remain patient. According to meteorologist Marc de Keyser, the weather window is slamming shut today.
From now until May 17, the wind will be too strong to summit, de Keyser explained. Here is a detailed explanation, courtesy of his Weather 4 Expeditions meteo service:
Upper air pattern and jet stream
The upstream branch of the subtropical jet stream is rapidly approaching, and the leading edge is now just west of Nepal. This jet is moving quite rapidly eastward and will move over the Himalaya later today. On Everest, this will lead to a significant wind increase between 18:00 and 21:00 UTC tonight.
This development is associated with the approach of a rather strong high-pressure ridge, which will have a favorable influence on the air mass. [It] will clear most of the clouds above 5,500/6,000m, and this will last for the best part of this period.
Change on May 18
Graph showing the wind speed at 7,000m in the next few days. Chart by Meteoexploration.com
De Keyser said that the weather itself will remain stable in the short term.
“Convection should be limited to the lowermost 5,000/5,500m of the mountain, while above this level, clouds will be mostly scattered,” he wrote. “At this stage, the models suggest a little bit deeper convection on May 18, which could make it all a bit more unstable below 7,000-8,000m.”
Diagram showing wind speed on Everest at 8,000m. Chart by Meteoexploration.com
Suggested summit days
De Keyser points to May 19-20 (Tuesday-Wednesday next week) as potentially good summit days.
“The wind will decrease later on the 17th and early on the 18th, but the 18th also shows deeper instability, which makes it a potential summit day, but it can still go either way,” he noted.
Diagram showing wind speed on Everest at summit altitude over the next few days. Chart: Meteoexploration.com
May 21 and 22 are also looking good at present, but conditions for those days are still subject to change.
Crowd alert
The question is whether 1,000+ climbers waiting in Base Camp or already heading up to Camp 2 will be patient enough. If they are and plan to head for the top on May 19, how crowded will the mountain be?
Meanwhile, dozens of Sherpas cannot afford to wait. The route between Camp 2 and Camp 4 is buzzing with activity: Expeditions need their highest camp, located at 7,900m on the South Col, pitched and supplied by the time a new window opens.
The summit of Everest yesterday, seen from a still deserted South Col. Photo: Karl Egloff
A line of Sherpas heads to Camp 4 last night. Photo: Gautham Khimal
