WMOD00310 ‎(2)‎

• Project Name: Sierra Cooperative Pilot Project
• Title: The Characteristics of Evolution of Supercooled Water in Wintertime Storms Over the Sierra Nevada
• Date: 9/9/1988
• Weather Modification - Doc Type: Report

SEPTEMBER 1988

MARK F. HEGGLI AND ROBERT M. RAUBER

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fiG. 3. General synoptic-scale storm patterns that produce storms over the Sierra Nevada. The solid lines represent 500 mb flow contours.
Cirrus clouds and lower troposphere clouds, based on satellite views of these storms, are indicated by dark and light shading, respectively.
The dark arrow indicates a typical trajectory of the vorticity maxima associated with the 500 mb trough.

region of split flow over the project area. A region of
cirrus and midlevel cloud was frequently observed
ahead of the surface front: but it had generally decou-
pled from the clouds associated with the surface front,
an extreme case of the Browning and Monk split-front

theory. As fronts moved over land into the Sierra Ne-
vada, they underwent frontolysis. Light and sporadic
precipitation accompanied the frontal passage in the
Sierra Nevada. An orographic cloud often persisted for
several hours after frontal passage.