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New Snowfall to Estimated Meltwater Conversion Table

When the water equivalent of snow cannot be accurately measured by melting, weighing, or core sampling; the observer shall estimate the water equivalent to the nearest 0.01 inch. Use Figure 11-8 (New Snowfall to Estimated Meltwater Conversion Table) only as a guide in estimating the water equivalency of newly fallen snow.

Excerpt from Surface Weather Observing - FAA Order 7900.5B 5/11/01

Figure 11-8 NEW SNOWFALL to ESTIMATED MELTWATER Conversion Table
Meltwater
Equivalent
(Inches)
New Snowfall (Inches)
Temperature (°F)
28° to 34° 20° to 27° 15° to 19° 10° to 14° 0° to 9° -1° to -20° -21° to -40°
trace trace 0.1 0.2 0.3 0.4 0.5 1.0
.01 0.1 0.2 0.2 0.3 0.4 0.5 1.0
.02 0.2 0.3 0.4 0.6 0.8 1.0 2.0
.03 0.3 0.5 0.6 0.9 1.2 1.5 3.0
.04 0.4 0.6 0.8 1.2 1.6 2.0 4.0
.05 0.5 0.8 1.0 1.5 2.0 2.5 5.0
.06 0.6 0.9 1.2 1.8 2.4 3.0 6.0
.07 0.7 1.1 1.4 2.1 2.8 3.5 7.0
.08 0.8 1.2 1.6 2.4 3.2 4.0 8.0
.09 0.9 1.4 1.8 2.7 3.6 4.5 9.0
.10 1.0 1.5 2.0 3.0 4.0 5.0 10.0
.11 1.1 1.7 2.2 3.3 4.4 5.5 11.0
.12 1.2 1.8 2.4 3.6 4.8 6.0 12.0
.13 1.3 2.0 2.6 3.9 5.2 6.5 13.0
.14 1.4 2.1 2.8 4.2 5.6 7.0 14.0
.15 1.5 2.3 3.0 4.5 6.0 7.5 15.0
.16 1.6 2.4 3.2 4.8 6.4 8.0 16.0
.17 1.7 2.6 3.4 5.1 6.8 8.5 17.0
.18 1.8 2.7 3.6 5.4 7.2 9.0 18.0
.19 1.9 2.9 3.8 5.7 7.6 9.5 19.0
.20 2.0 3.0 4.0 6.0 8.0 10.0 20.0
.21 2.1 3.1 4.2 6.3 8.4 10.5 21.0
.22 2.2 3.3 4.4 6.6 8.8 11.0 22.0
.23 2.3 3.4 4.6 6.9 9.2 11.5 23.0
.24 2.4 3.6 4.8 7.2 9.6 12.0 24.0
.25 2.5 3.8 5.0 7.5 10.0 12.5 25.0
.30 3.0 4.5 6.0 9.0 12.0 15.0 30.0
.35 3.5 5.3 7.0 10.5 14.0 17.5 35.0
.40 4.0 6.0 8.0 12.0 16.0 20.0 40.0
.45 4.5 6.8 9.0 13.5 18.0 22.5 40.0
.50 5.0 7.5 10.0 15.0 20.0 25.0 50.0
.60 6.0 9.0 12.0 18.0 24.0 30.0 60.0
.70 7.0 10.5 14.0 21.0 28.0 35.0 70.0
.80 8.0 12.0 16.0 24.0 32.0 40.0 80.0
.90 9.0 13.5 18.0 27.0 36.0 45.0 90.0
1.00 10.0 15.0 20.0 30.0 40.0 50.0 100.0
2.00 20.0 30.0 40.0 60.0 80.0 100.0 200.0
3.00 30.0 45.0 60.0 90.0 120.0 150.0 300.0
This figure can only be used in determining amounts of newly fallen snow. It cannot be used for determining the water equivalency of "old" snow. Packing and melting/refreezing have substantial effects on the density of the snow pack and are not accounted for by this figure.