Mountain WeatherMITOC Winter School 2002

Robert Zeithammer

Why Weather?

October 12, 1999 …top of Mount Madison

Weather Changes

• January 1: Temperature 3 degrees;• Snow, freezing fog, wind chill –50• Visibility: 100 feet

Moosilauke Skiing Trip, Winter School 2001

Weather Safety

• Check the forecast (but don’t rely on it!!!)– http://met-www.cit.cornell.edu/cgi-bin/fcst?NH004– http://www.mountwashington.org/weather/today.html

• Daily weather-report• Higher-summits forecast• Backcountry conditions

• Stay alert to weather changes– Clouds and winds provide big hints

• Come prepared for the worst!!!

What’s “worst”?• 30 F, heavy rain, any wind a bonus

• -10 F, 60 MPH wind : feels like –50F

Mount Washington at the confluence of three major storm-tracks.

In the Whites, wind is the biggest concern.– It makes you cold (wind chill)– It knocks you over (70 MPH enough)– It likely makes visibility unreliable– It increases avalanche danger

Exact #s unimportant. Basic idea crucial!

Presidential

Reverse,

February 2001

Mountains get bad weather

Cirrus Clouds

High altitude clouds; good weather, possible rain in 12-24 hours for some types

Cumulus Clouds

• Nice weather, but keep an eye out

Nimbostratus Clouds

• Lower (2000m) clouds

• Rain or snow coming soon

Cumulonimbus

Clouds with vertical growth (“Anvils”)(May not see the anvil when close)Heavy rain, snow, hail, lightning!

Blue Skies

• Good weather has its downsides too: The Sun (it’s a mass of incandescent gas…)

• Sunburn can be serious– Light and U/V reflected by snow and ice– Sunburned retinas and mouths are not fun

• Sunscreen, long-sleeved clothing, and sunglasses will make you happier

Weather Summary

• Check forecasts, check the skies often– Neither is a perfect predictor, so be prepared.

• Take-home lesson: STAY ALERT. Weather changes rapidly.

• When in doubt, RETREAT!!!