WMOD00584

• Title: Use of Nested Models to Simulate Regional Orographic Precipitation
• Date: 11/1/1992
• Weather Modification - Doc Type: Report

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Figure 1. Three-dimensional topography
used in the MM4 and Clark model
simulations as viewed from the southwest
corner of the grids. Dashes show the
nesting of the local-scale Clark model
into the MM4's regional domain.
Relative locations of DEN (Denver) and
GJT (Grand Junction) rawinsonde sites
are shown. Note that MM4's coarse 60-km
resolution fails to resolve major river
basins; however, the 10-km iesolution
Clark model topography defines major
river basins and that of their
tributaries within the Gunnison Basin.

Figure 2. Monsoon flow and
precipitation over the West:.. MM4
simulations of the monsoon flow at 700
mb on July 20, 1983, at 0000 UTC(figure
2a) . Vectors indicate airflow with
moisture sources in the Gulf of Mexico
and Pacific marked by bold arrows.
MM4 g+id points are marked by small dots
and wind vectors are plotted at every
3rd point. Large dots (0) show the very
coarse resolution of the general
circulation model (CCM) grid with - 500-
km resolution. The nested Clark model
domains for 10-km (solid bold square)
and 5-km resolution (dashed s~lare) are
marked over the Gunnison Basin.
Precipitation predicted by MM4 from 1200
UTC on July 19 to 1200 UTC July 20,
1983, shows a 5-cm maximum over Colorado
(figure 2b) .