|
|
Getting and analyzing
weather forecasts
In 1999 we shared reports from the operational
center of The Met. Office at Bracknell, UK. The reports must be tailor
made and cost around 200 UsD each. The trouble was that small
expeditions and independent climbers were charged the same cost as large
expeditions, making the service more expensive for some. These years,
there are reports made by many international met stations and subscribed
to individually by expeditions, often on a sponsor basis. Share all
reports and compare for best safety.
Get the forecast every third day or so from when you start climbing,
and then every day on the summit days. The forecast will typically be
done for 4-5 days ahead and more accurate the closer to the climb it is
done. You need some basic knowledge to read the forecast:
Everest position is 28N and 87E. You need to bring a map to position
the jet stream and various weather systems.
Read the table as follows:
- FL100 = 10000 feet
- 230/02 = wind direction 230 degrees with 2 knots
- PS16 = plus 16 Celsius (MS = minus).
Below is an example of two different forecasts, received in the
spring of 1999, May 7 and May 28:
| Day 1, May 7
General Synopsis: A
weak upper trough over Everest early in the day will move away to
east, replaced by a ridge of high pressure.
Position of Jet stream in relation to Mt. Everest: Over Pakistan,
SW 80kts, at first propagating east to lie over, or just north of,
Everest, W 60kts, by the end of the day.
Valid at 1200 GMT Fri 7 May Valid at 2359 GMT
Fri 7 May
Height Wind (True & Kt) Temp (C) Height Wind (True &
Kt) Temp (C)
FL100 230/02 PS16 FL100 350/08
PS09
FL180 290/07 MS04 FL180
350/10MS08
FL240 300/09 MS17 FL240
280/17MS19
FL300 280/35 MS33 FL300 280/57
MS34
Cloud: Broken Cu building by day, with broken Ci throughout.
Weather: Mainly fair, small chance of a snow shower, especially
later. |
|
Day 1, May 28
General Synopsis:
Weak Upper Ridge just east of Everest, axis between 40N 95E & 30N
92E, with a broad trough to the west axis near 45N 75E to 32N 73E.
Position of Jet stream in relation to Mt Everest: Jet well to the
north of location between 45N 60E and 40N 92E. Core speed 95 knots
near 39N 84E. Position of Monsoon: Invigoration of the Monsoon
Trough in the Bay of Bengal, with the main activity as far north
as 22N, but with an extension of this activity as far north as 30N
further east (near 100E).
Valid at 1200 GMT Fri
28 May Valid at 2359 GMTFri 28 May
Height Wind (True & Kt) Temp (C) Height Wind (True & Kt)
Temp (C)
FL100 220/05 +12 FL100 VRB/05
+12
FL180 240/10 -03 FL180 -03
FL240 270/10 -12 FL240 -11
FL300 280/10 -26 FL300 -27
Cloud: BKN/OVC ACASCI, with ISOL CUCB.
Weather: Snow showers at upper levels. |
Conclusions to be made from those reports:
May 7 is not a good day for climbing. Note the change
from a trough to a region of high pressure. The jet wind is right at or
very close to Everest and the wind on the summit (FL300) will be 57
knots.
On May 28 it's a totally different story. The jet wind
is well to the north, the monsoon is moving and the wind is 10 knots! An
excellent day for a summit attempt.
The weather reports provided by ExplorersWeb today are
adjusted to climbers suggestions for improvement and easier to read, but
youŽll still have to understand and interpret the facts.
Other sources of weather
information
 The
second best weather source is the Sherpas. They normally have a great
sense, especially for when not to climb. They have lived in the area for
centuries and should always be listened to. However, their judgment
might sometimes be somewhat biased and connected to overall motivation
of climbing. Listen, think and make your own judgment.
Weather talk is one of the main topics with fellow
climbers. Unfortunately, few actually read and try to understand the
weather reports. Once again, listen, think and make your own judgment.
|
|
