Yosemite Valley
Sierra Nevada, California · 37.75°N, 119.59°W · 1,209 m (3,967 ft) · Mountain
Solid lines are ensemble medians; the darker band holds the middle half of the members and the lighter band the middle 80%. Dashed lines are the single deterministic runs. The strips above Lead I show the share of members in atmospheric river conditions. Arrows along the foot of Lead I point the way the vapor is moving.
The numbers as a table
Nearby in Sierra Nevada
How to read this
IVT, integrated vapor transport, is how much water vapor the wind carries past a point through the depth of the lower atmosphere. A reading of 250 kg m⁻¹ s⁻¹ or more marks atmospheric river conditions. The AR scale (Ralph and others, 2019) ranks each spell from 1 to 5 by its peak IVT and how long it lasts: 48 hours or more moves it up one rank, under 24 hours moves it down one.
Precipitable water is the vapor overhead, as the depth of rain it would make if all of it fell. Transport needs both vapor and wind, so a high reading with weak wind gives little IVT.
Everything here is read at the nearest point of the models' 0.25° grid, about 25 km across. Mountains are smoothed at that scale, so real rain and snow totals on steep terrain are often higher than the models show, and the snow line can sit well off. Snowfall is shown as its water equivalent.
Data: ECMWF open data (IFS, AIFS and their 51-member ensembles), CC BY 4.0. Charts are drawn in your browser from the point store, and update with every model run.