As Paul approaches the summit of Everest we know his thinking is dominated by the weather.
Hello, this is Nick Grainger in Melbourne. I’m the website and communications coordinator, and I thought I’d give everyone some insight into where Paul is getting weather forecasts from, what they look like, how they have influenced him over the last week, and what is forecast for the next few days.
There are no free detailed weather forecasting services for the Everest region. So it’s not just a matter of turning on the radio or logging into a weather bureau site. But summit attempts are absolutely dependent on the weather. Last year Paul was reliant on others subscribing to and interpreting commercial forecasts. This year he decided to do it himself. With a contribution from Attila and Meagan, Paul subscribed to a daily Everest forecast from Meteotest, an independent private company, founded in 1981 and based in Switzerland, that specialises in preparing weather forecasts for anywhere in the world.
Each day for the last week or so the on-duty forecaster at Meteotest has emailed me a rolling forecast for the next 7 days. This has usually arrived about my lunchtime and comprises a brief narrative commentary on the situation supported by a ‘Meteogram’, a one page compilation of weather chart data for the next week and a wind ensemble chart which shows the forecast wind above the summit on each day as calculated using a series of forecasting models. The output from each model is shown by a different colour line. If they are all close together the forecast is considered more reliable. Also included on some days is a series of images showing the forecast position of the jet stream over the Everest region.
Processing forecasts for the Everest team
As received the forecast package can be nearly a megabyte of data, much too big a file for Paul and the others to receive via their satellite phones and PDAs. These only allow a very slow link to the Internet, so big files are out. In order to send it to Paul, Meagan and Attila, I reduce it to a much smaller file by just selecting the images of most use, reducing their size and changing their file compression. At the same time I sometimes expand on the description and implications of the forecast because whilst I can see all the charts on my big screen on my desk, on Everest the team can only view a bit at time on their tiny PDA screens. So it’s much easier for me to see the whole picture than for them. Interpretation may be a bit easier too because I’m near sea level in thick air, not way above 20,000 feet in very cold thin air. And I’ve done it at sea a lot.
Why Paul delayed at Camp 2
Ardent followers of Paul’s climb will know that he paused for Saturday and Sunday at camp 2. This was due to the trend of forecasts received on Thursday and Friday, which indicated a jet stream driven change in weather systems passing over Everest on Monday and Tuesday. See the meteogram (right). Before the change the wind would be from the south, bringing snow and cloudy conditions, particularly in the afternoons. However the wind was forecast to abruptly shift to the north on Tuesday, bringing dry clear air over the mountain by late Tuesday, early Wednesday and continuing for the rest of the week. Such change can sometimes bring strong gusty conditions. After the change to the north, the wind was forecast to be initially light but steadily building during the rest of the week and swinging to the west. Overall the weather on Wednesday looked much more stable, and to be ideal for a summit attempt. As Paul said, the forecasts had been right so far, and he intended to continue to trust them. Attila decided to do the same, and wait for the change to pass before heading up the exposed Lhotse face to Camp 3 and 4. Meagan however decided to press on.
As it happened the southerlies of Saturday, Sunday and Monday dumped relatively little snow, and the wind shift from south to north came through late on Monday and passed relatively uneventfully. Meagan and a number of others successfully summited and returned safely.
Paul and Attila are now on their way up, and in less than 12 hours will be setting off on their summit attempt from Camp 4. How is the weather forecast looking now?
In the most recent forecast, just received from Switzerland, duty forecaster Jurg says the conditions for the rest of the week remain stable, however the wind is expected to increase steadily from the west. Winds of less than 5 knots on the summit on Wednesday were forecast a day or so ago, but now are expected to be approaching 20 knots and to steadily increase on Thursday and Friday. But it should be dry and clear.
Will this affect Paul and Attila’s summit attempt? The summit of Mt Everest sticks into jet stream altitudes. Conditions can be almost unimaginably fierce. Weather forecasters can only look at the signs, and model them against history. In the end it’s the climber, the person there, that has to use their judgment.